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/compile.hpp"
40 #include "opto/connode.hpp"
41 #include "opto/convertnode.hpp"
42 #include "opto/inlinetypenode.hpp"
43 #include "opto/loopnode.hpp"
44 #include "opto/machnode.hpp"
45 #include "opto/matcher.hpp"
46 #include "opto/memnode.hpp"
47 #include "opto/mempointer.hpp"
48 #include "opto/mulnode.hpp"
49 #include "opto/narrowptrnode.hpp"
50 #include "opto/phaseX.hpp"
51 #include "opto/regalloc.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 shift = ary_t->is_flat() ? ary_t->flat_log_elem_size() : exact_log2(type2aelembytes(ary_elem));
1194
1195 Node* diff = phase->transform(new SubINode(ac->in(ArrayCopyNode::SrcPos), ac->in(ArrayCopyNode::DestPos)));
1196 #ifdef _LP64
1197 diff = phase->transform(new ConvI2LNode(diff));
1198 #endif
1199 diff = phase->transform(new LShiftXNode(diff, phase->intcon(shift)));
1200
1201 Node* offset = phase->transform(new AddXNode(addp->in(AddPNode::Offset), diff));
1202 addp->set_req(AddPNode::Offset, offset);
1203 }
1204 addp = phase->transform(addp);
1205 #ifdef ASSERT
1206 const TypePtr* adr_type = phase->type(addp)->is_ptr();
1207 ld->_adr_type = adr_type;
1208 #endif
1209 ld->set_req(MemNode::Address, addp);
1210 ld->set_req(0, ctl);
1211 ld->set_req(MemNode::Memory, mem);
1212 return ld;
1213 }
1214 return nullptr;
1215 }
1216
1217 static Node* see_through_inline_type(PhaseValues* phase, const MemNode* load, Node* base, int offset) {
1218 if (!load->is_mismatched_access() && base != nullptr && base->is_InlineType() && offset > oopDesc::klass_offset_in_bytes()) {
1219 InlineTypeNode* vt = base->as_InlineType();
1220 Node* value = vt->field_value_by_offset(offset, true);
1221 assert(value != nullptr, "must see some value");
1222 return value;
1223 }
1224
1225 return nullptr;
1226 }
1227
1228 //---------------------------can_see_stored_value------------------------------
1229 // This routine exists to make sure this set of tests is done the same
1230 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
1231 // will change the graph shape in a way which makes memory alive twice at the
1232 // same time (uses the Oracle model of aliasing), then some
1233 // LoadXNode::Identity will fold things back to the equivalence-class model
1234 // of aliasing.
1235 Node* MemNode::can_see_stored_value(Node* st, PhaseValues* phase) const {
1236 Node* ld_adr = in(MemNode::Address);
1237 intptr_t ld_off = 0;
1238 Node* ld_base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ld_off);
1239 // Try to see through an InlineTypeNode
1240 // LoadN is special because the input is not compressed
1241 if (Opcode() != Op_LoadN) {
1242 Node* value = see_through_inline_type(phase, this, ld_base, ld_off);
1243 if (value != nullptr) {
1244 return value;
1245 }
1246 }
1247
1248 Node* ld_alloc = AllocateNode::Ideal_allocation(ld_base);
1249 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
1250 Compile::AliasType* atp = (tp != nullptr) ? phase->C->alias_type(tp) : nullptr;
1251 // This is more general than load from boxing objects.
1252 if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) {
1253 uint alias_idx = atp->index();
1254 Node* result = nullptr;
1255 Node* current = st;
1256 // Skip through chains of MemBarNodes checking the MergeMems for
1257 // new states for the slice of this load. Stop once any other
1258 // kind of node is encountered. Loads from final memory can skip
1259 // through any kind of MemBar but normal loads shouldn't skip
1260 // through MemBarAcquire since the could allow them to move out of
1261 // a synchronized region. It is not safe to step over MemBarCPUOrder,
1262 // because alias info above them may be inaccurate (e.g., due to
1263 // mixed/mismatched unsafe accesses).
1264 bool is_final_mem = !atp->is_rewritable();
1265 while (current->is_Proj()) {
1266 int opc = current->in(0)->Opcode();
1267 if ((is_final_mem && (opc == Op_MemBarAcquire ||
1268 opc == Op_MemBarAcquireLock ||
1269 opc == Op_LoadFence)) ||
1270 opc == Op_MemBarRelease ||
1271 opc == Op_StoreFence ||
1272 opc == Op_MemBarReleaseLock ||
1273 opc == Op_MemBarStoreStore ||
1274 opc == Op_StoreStoreFence) {
1275 Node* mem = current->in(0)->in(TypeFunc::Memory);
1276 if (mem->is_MergeMem()) {
1277 MergeMemNode* merge = mem->as_MergeMem();
1278 Node* new_st = merge->memory_at(alias_idx);
1279 if (new_st == merge->base_memory()) {
1280 // Keep searching
1281 current = new_st;
1282 continue;
1283 }
1284 // Save the new memory state for the slice and fall through
1285 // to exit.
1286 result = new_st;
1287 }
1288 }
1289 break;
1290 }
1291 if (result != nullptr) {
1292 st = result;
1293 }
1294 }
1295
1296 // Loop around twice in the case Load -> Initialize -> Store.
1297 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
1298 for (int trip = 0; trip <= 1; trip++) {
1299
1300 if (st->is_Store()) {
1301 Node* st_adr = st->in(MemNode::Address);
1302 if (st_adr != ld_adr) {
1303 // Try harder before giving up. Unify base pointers with casts (e.g., raw/non-raw pointers).
1304 intptr_t st_off = 0;
1305 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_off);
1306 if (ld_base == nullptr) return nullptr;
1307 if (st_base == nullptr) return nullptr;
1308 if (!ld_base->eqv_uncast(st_base, /*keep_deps=*/true)) return nullptr;
1309 if (ld_off != st_off) return nullptr;
1310 if (ld_off == Type::OffsetBot) return nullptr;
1311 // Same base, same offset.
1312 // Possible improvement for arrays: check index value instead of absolute offset.
1313
1314 // At this point we have proven something like this setup:
1315 // B = << base >>
1316 // L = LoadQ(AddP(Check/CastPP(B), #Off))
1317 // S = StoreQ(AddP( B , #Off), V)
1318 // (Actually, we haven't yet proven the Q's are the same.)
1319 // In other words, we are loading from a casted version of
1320 // the same pointer-and-offset that we stored to.
1321 // Casted version may carry a dependency and it is respected.
1322 // Thus, we are able to replace L by V.
1323 }
1324 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
1325 if (store_Opcode() != st->Opcode()) {
1326 return nullptr;
1327 }
1328 // LoadVector/StoreVector needs additional check to ensure the types match.
1329 if (st->is_StoreVector()) {
1330 const TypeVect* in_vt = st->as_StoreVector()->vect_type();
1331 const TypeVect* out_vt = is_Load() ? as_LoadVector()->vect_type() : as_StoreVector()->vect_type();
1332 if (in_vt != out_vt) {
1333 return nullptr;
1334 }
1335 }
1336 return st->in(MemNode::ValueIn);
1337 }
1338
1339 // A load from a freshly-created object always returns zero.
1340 // (This can happen after LoadNode::Ideal resets the load's memory input
1341 // to find_captured_store, which returned InitializeNode::zero_memory.)
1342 if (st->is_Proj() && st->in(0)->is_Allocate() &&
1343 (st->in(0) == ld_alloc) &&
1344 (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) {
1345 // return a zero value for the load's basic type
1346 // (This is one of the few places where a generic PhaseTransform
1347 // can create new nodes. Think of it as lazily manifesting
1348 // virtually pre-existing constants.)
1349 Node* init_value = ld_alloc->in(AllocateNode::InitValue);
1350 if (init_value != nullptr) {
1351 // TODO 8350865 Scalar replacement does not work well for flat arrays.
1352 // Is this correct for non-all-zero init values? Don't we need field_value_by_offset?
1353 return init_value;
1354 }
1355 assert(ld_alloc->in(AllocateNode::RawInitValue) == nullptr, "init value may not be null");
1356 if (value_basic_type() != T_VOID) {
1357 if (ReduceBulkZeroing || find_array_copy_clone(ld_alloc, in(MemNode::Memory)) == nullptr) {
1358 // If ReduceBulkZeroing is disabled, we need to check if the allocation does not belong to an
1359 // ArrayCopyNode clone. If it does, then we cannot assume zero since the initialization is done
1360 // by the ArrayCopyNode.
1361 return phase->zerocon(value_basic_type());
1362 }
1363 } else {
1364 // TODO: materialize all-zero vector constant
1365 assert(!isa_Load() || as_Load()->type()->isa_vect(), "");
1366 }
1367 }
1368
1369 // A load from an initialization barrier can match a captured store.
1370 if (st->is_Proj() && st->in(0)->is_Initialize()) {
1371 InitializeNode* init = st->in(0)->as_Initialize();
1372 AllocateNode* alloc = init->allocation();
1373 if ((alloc != nullptr) && (alloc == ld_alloc)) {
1374 // examine a captured store value
1375 st = init->find_captured_store(ld_off, memory_size(), phase);
1376 if (st != nullptr) {
1377 continue; // take one more trip around
1378 }
1379 }
1380 }
1381
1382 // Load boxed value from result of valueOf() call is input parameter.
1383 if (this->is_Load() && ld_adr->is_AddP() &&
1384 (tp != nullptr) && tp->is_ptr_to_boxed_value()) {
1385 intptr_t ignore = 0;
1386 Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore);
1387 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1388 base = bs->step_over_gc_barrier(base);
1389 if (base != nullptr && base->is_Proj() &&
1390 base->as_Proj()->_con == TypeFunc::Parms &&
1391 base->in(0)->is_CallStaticJava() &&
1392 base->in(0)->as_CallStaticJava()->is_boxing_method()) {
1393 return base->in(0)->in(TypeFunc::Parms);
1394 }
1395 }
1396
1397 break;
1398 }
1399
1400 return nullptr;
1401 }
1402
1403 //----------------------is_instance_field_load_with_local_phi------------------
1404 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
1405 if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl &&
1406 in(Address)->is_AddP() ) {
1407 const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr();
1408 // Only instances and boxed values.
1409 if( t_oop != nullptr &&
1410 (t_oop->is_ptr_to_boxed_value() ||
1411 t_oop->is_known_instance_field()) &&
1412 t_oop->offset() != Type::OffsetBot &&
1413 t_oop->offset() != Type::OffsetTop) {
1414 return true;
1415 }
1416 }
1417 return false;
1418 }
1419
1420 //------------------------------Identity---------------------------------------
1421 // Loads are identity if previous store is to same address
1422 Node* LoadNode::Identity(PhaseGVN* phase) {
1423 // If the previous store-maker is the right kind of Store, and the store is
1424 // to the same address, then we are equal to the value stored.
1425 Node* mem = in(Memory);
1426 Node* value = can_see_stored_value(mem, phase);
1427 if( value ) {
1428 // byte, short & char stores truncate naturally.
1429 // A load has to load the truncated value which requires
1430 // some sort of masking operation and that requires an
1431 // Ideal call instead of an Identity call.
1432 if (memory_size() < BytesPerInt) {
1433 // If the input to the store does not fit with the load's result type,
1434 // it must be truncated via an Ideal call.
1435 if (!phase->type(value)->higher_equal(phase->type(this)))
1436 return this;
1437 }
1438 // (This works even when value is a Con, but LoadNode::Value
1439 // usually runs first, producing the singleton type of the Con.)
1440 if (!has_pinned_control_dependency() || value->is_Con()) {
1441 return value;
1442 } else {
1443 return this;
1444 }
1445 }
1446
1447 if (has_pinned_control_dependency()) {
1448 return this;
1449 }
1450 // Search for an existing data phi which was generated before for the same
1451 // instance's field to avoid infinite generation of phis in a loop.
1452 Node *region = mem->in(0);
1453 if (is_instance_field_load_with_local_phi(region)) {
1454 const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr();
1455 int this_index = phase->C->get_alias_index(addr_t);
1456 int this_offset = addr_t->offset();
1457 int this_iid = addr_t->instance_id();
1458 if (!addr_t->is_known_instance() &&
1459 addr_t->is_ptr_to_boxed_value()) {
1460 // Use _idx of address base (could be Phi node) for boxed values.
1461 intptr_t ignore = 0;
1462 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1463 if (base == nullptr) {
1464 return this;
1465 }
1466 this_iid = base->_idx;
1467 }
1468 const Type* this_type = bottom_type();
1469 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1470 Node* phi = region->fast_out(i);
1471 if (phi->is_Phi() && phi != mem &&
1472 phi->as_Phi()->is_same_inst_field(this_type, (int)mem->_idx, this_iid, this_index, this_offset)) {
1473 return phi;
1474 }
1475 }
1476 }
1477
1478 return this;
1479 }
1480
1481 // Construct an equivalent unsigned load.
1482 Node* LoadNode::convert_to_unsigned_load(PhaseGVN& gvn) {
1483 BasicType bt = T_ILLEGAL;
1484 const Type* rt = nullptr;
1485 switch (Opcode()) {
1486 case Op_LoadUB: return this;
1487 case Op_LoadUS: return this;
1488 case Op_LoadB: bt = T_BOOLEAN; rt = TypeInt::UBYTE; break;
1489 case Op_LoadS: bt = T_CHAR; rt = TypeInt::CHAR; break;
1490 default:
1491 assert(false, "no unsigned variant: %s", Name());
1492 return nullptr;
1493 }
1494 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1495 raw_adr_type(), rt, bt, _mo, _control_dependency,
1496 false /*require_atomic_access*/, is_unaligned_access(), is_mismatched_access());
1497 }
1498
1499 // Construct an equivalent signed load.
1500 Node* LoadNode::convert_to_signed_load(PhaseGVN& gvn) {
1501 BasicType bt = T_ILLEGAL;
1502 const Type* rt = nullptr;
1503 switch (Opcode()) {
1504 case Op_LoadUB: bt = T_BYTE; rt = TypeInt::BYTE; break;
1505 case Op_LoadUS: bt = T_SHORT; rt = TypeInt::SHORT; break;
1506 case Op_LoadB: // fall through
1507 case Op_LoadS: // fall through
1508 case Op_LoadI: // fall through
1509 case Op_LoadL: return this;
1510 default:
1511 assert(false, "no signed variant: %s", Name());
1512 return nullptr;
1513 }
1514 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1515 raw_adr_type(), rt, bt, _mo, _control_dependency,
1516 false /*require_atomic_access*/, is_unaligned_access(), is_mismatched_access());
1517 }
1518
1519 bool LoadNode::has_reinterpret_variant(const Type* rt) {
1520 BasicType bt = rt->basic_type();
1521 switch (Opcode()) {
1522 case Op_LoadI: return (bt == T_FLOAT);
1523 case Op_LoadL: return (bt == T_DOUBLE);
1524 case Op_LoadF: return (bt == T_INT);
1525 case Op_LoadD: return (bt == T_LONG);
1526
1527 default: return false;
1528 }
1529 }
1530
1531 Node* LoadNode::convert_to_reinterpret_load(PhaseGVN& gvn, const Type* rt) {
1532 BasicType bt = rt->basic_type();
1533 assert(has_reinterpret_variant(rt), "no reinterpret variant: %s %s", Name(), type2name(bt));
1534 bool is_mismatched = is_mismatched_access();
1535 const TypeRawPtr* raw_type = gvn.type(in(MemNode::Memory))->isa_rawptr();
1536 if (raw_type == nullptr) {
1537 is_mismatched = true; // conservatively match all non-raw accesses as mismatched
1538 }
1539 const int op = Opcode();
1540 bool require_atomic_access = (op == Op_LoadL && ((LoadLNode*)this)->require_atomic_access()) ||
1541 (op == Op_LoadD && ((LoadDNode*)this)->require_atomic_access());
1542 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1543 raw_adr_type(), rt, bt, _mo, _control_dependency,
1544 require_atomic_access, is_unaligned_access(), is_mismatched);
1545 }
1546
1547 bool StoreNode::has_reinterpret_variant(const Type* vt) {
1548 BasicType bt = vt->basic_type();
1549 switch (Opcode()) {
1550 case Op_StoreI: return (bt == T_FLOAT);
1551 case Op_StoreL: return (bt == T_DOUBLE);
1552 case Op_StoreF: return (bt == T_INT);
1553 case Op_StoreD: return (bt == T_LONG);
1554
1555 default: return false;
1556 }
1557 }
1558
1559 Node* StoreNode::convert_to_reinterpret_store(PhaseGVN& gvn, Node* val, const Type* vt) {
1560 BasicType bt = vt->basic_type();
1561 assert(has_reinterpret_variant(vt), "no reinterpret variant: %s %s", Name(), type2name(bt));
1562 const int op = Opcode();
1563 bool require_atomic_access = (op == Op_StoreL && ((StoreLNode*)this)->require_atomic_access()) ||
1564 (op == Op_StoreD && ((StoreDNode*)this)->require_atomic_access());
1565 StoreNode* st = StoreNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1566 raw_adr_type(), val, bt, _mo, require_atomic_access);
1567
1568 bool is_mismatched = is_mismatched_access();
1569 const TypeRawPtr* raw_type = gvn.type(in(MemNode::Memory))->isa_rawptr();
1570 if (raw_type == nullptr) {
1571 is_mismatched = true; // conservatively match all non-raw accesses as mismatched
1572 }
1573 if (is_mismatched) {
1574 st->set_mismatched_access();
1575 }
1576 return st;
1577 }
1578
1579 // We're loading from an object which has autobox behaviour.
1580 // If this object is result of a valueOf call we'll have a phi
1581 // merging a newly allocated object and a load from the cache.
1582 // We want to replace this load with the original incoming
1583 // argument to the valueOf call.
1584 Node* LoadNode::eliminate_autobox(PhaseIterGVN* igvn) {
1585 assert(igvn->C->eliminate_boxing(), "sanity");
1586 intptr_t ignore = 0;
1587 Node* base = AddPNode::Ideal_base_and_offset(in(Address), igvn, ignore);
1588 if ((base == nullptr) || base->is_Phi()) {
1589 // Push the loads from the phi that comes from valueOf up
1590 // through it to allow elimination of the loads and the recovery
1591 // of the original value. It is done in split_through_phi().
1592 return nullptr;
1593 } else if (base->is_Load() ||
1594 (base->is_DecodeN() && base->in(1)->is_Load())) {
1595 // Eliminate the load of boxed value for integer types from the cache
1596 // array by deriving the value from the index into the array.
1597 // Capture the offset of the load and then reverse the computation.
1598
1599 // Get LoadN node which loads a boxing object from 'cache' array.
1600 if (base->is_DecodeN()) {
1601 base = base->in(1);
1602 }
1603 if (!base->in(Address)->is_AddP()) {
1604 return nullptr; // Complex address
1605 }
1606 AddPNode* address = base->in(Address)->as_AddP();
1607 Node* cache_base = address->in(AddPNode::Base);
1608 if ((cache_base != nullptr) && cache_base->is_DecodeN()) {
1609 // Get ConP node which is static 'cache' field.
1610 cache_base = cache_base->in(1);
1611 }
1612 if ((cache_base != nullptr) && cache_base->is_Con()) {
1613 const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr();
1614 if ((base_type != nullptr) && base_type->is_autobox_cache()) {
1615 Node* elements[4];
1616 int shift = exact_log2(type2aelembytes(T_OBJECT));
1617 int count = address->unpack_offsets(elements, ARRAY_SIZE(elements));
1618 if (count > 0 && elements[0]->is_Con() &&
1619 (count == 1 ||
1620 (count == 2 && elements[1]->Opcode() == Op_LShiftX &&
1621 elements[1]->in(2) == igvn->intcon(shift)))) {
1622 ciObjArray* array = base_type->const_oop()->as_obj_array();
1623 // Fetch the box object cache[0] at the base of the array and get its value
1624 ciInstance* box = array->obj_at(0)->as_instance();
1625 ciInstanceKlass* ik = box->klass()->as_instance_klass();
1626 assert(ik->is_box_klass(), "sanity");
1627 assert(ik->nof_nonstatic_fields() == 1, "change following code");
1628 if (ik->nof_nonstatic_fields() == 1) {
1629 // This should be true nonstatic_field_at requires calling
1630 // nof_nonstatic_fields so check it anyway
1631 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1632 BasicType bt = c.basic_type();
1633 // Only integer types have boxing cache.
1634 assert(bt == T_BOOLEAN || bt == T_CHAR ||
1635 bt == T_BYTE || bt == T_SHORT ||
1636 bt == T_INT || bt == T_LONG, "wrong type = %s", type2name(bt));
1637 jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int();
1638 if (cache_low != (int)cache_low) {
1639 return nullptr; // should not happen since cache is array indexed by value
1640 }
1641 jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift);
1642 if (offset != (int)offset) {
1643 return nullptr; // should not happen since cache is array indexed by value
1644 }
1645 // Add up all the offsets making of the address of the load
1646 Node* result = elements[0];
1647 for (int i = 1; i < count; i++) {
1648 result = igvn->transform(new AddXNode(result, elements[i]));
1649 }
1650 // Remove the constant offset from the address and then
1651 result = igvn->transform(new AddXNode(result, igvn->MakeConX(-(int)offset)));
1652 // remove the scaling of the offset to recover the original index.
1653 if (result->Opcode() == Op_LShiftX && result->in(2) == igvn->intcon(shift)) {
1654 // Peel the shift off directly but wrap it in a dummy node
1655 // since Ideal can't return existing nodes
1656 igvn->_worklist.push(result); // remove dead node later
1657 result = new RShiftXNode(result->in(1), igvn->intcon(0));
1658 } else if (result->is_Add() && result->in(2)->is_Con() &&
1659 result->in(1)->Opcode() == Op_LShiftX &&
1660 result->in(1)->in(2) == igvn->intcon(shift)) {
1661 // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z)
1662 // but for boxing cache access we know that X<<Z will not overflow
1663 // (there is range check) so we do this optimizatrion by hand here.
1664 igvn->_worklist.push(result); // remove dead node later
1665 Node* add_con = new RShiftXNode(result->in(2), igvn->intcon(shift));
1666 result = new AddXNode(result->in(1)->in(1), igvn->transform(add_con));
1667 } else {
1668 result = new RShiftXNode(result, igvn->intcon(shift));
1669 }
1670 #ifdef _LP64
1671 if (bt != T_LONG) {
1672 result = new ConvL2INode(igvn->transform(result));
1673 }
1674 #else
1675 if (bt == T_LONG) {
1676 result = new ConvI2LNode(igvn->transform(result));
1677 }
1678 #endif
1679 // Boxing/unboxing can be done from signed & unsigned loads (e.g. LoadUB -> ... -> LoadB pair).
1680 // Need to preserve unboxing load type if it is unsigned.
1681 switch(this->Opcode()) {
1682 case Op_LoadUB:
1683 result = new AndINode(igvn->transform(result), igvn->intcon(0xFF));
1684 break;
1685 case Op_LoadUS:
1686 result = new AndINode(igvn->transform(result), igvn->intcon(0xFFFF));
1687 break;
1688 }
1689 return result;
1690 }
1691 }
1692 }
1693 }
1694 }
1695 return nullptr;
1696 }
1697
1698 static bool stable_phi(PhiNode* phi, PhaseGVN *phase) {
1699 Node* region = phi->in(0);
1700 if (region == nullptr) {
1701 return false; // Wait stable graph
1702 }
1703 uint cnt = phi->req();
1704 for (uint i = 1; i < cnt; i++) {
1705 Node* rc = region->in(i);
1706 if (rc == nullptr || phase->type(rc) == Type::TOP)
1707 return false; // Wait stable graph
1708 Node* in = phi->in(i);
1709 if (in == nullptr || phase->type(in) == Type::TOP)
1710 return false; // Wait stable graph
1711 }
1712 return true;
1713 }
1714
1715 //------------------------------split_through_phi------------------------------
1716 // Check whether a call to 'split_through_phi' would split this load through the
1717 // Phi *base*. This method is essentially a copy of the validations performed
1718 // by 'split_through_phi'. The first use of this method was in EA code as part
1719 // of simplification of allocation merges.
1720 // Some differences from original method (split_through_phi):
1721 // - If base->is_CastPP(): base = base->in(1)
1722 bool LoadNode::can_split_through_phi_base(PhaseGVN* phase) {
1723 Node* mem = in(Memory);
1724 Node* address = in(Address);
1725 intptr_t ignore = 0;
1726 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1727
1728 if (base->is_CastPP()) {
1729 base = base->in(1);
1730 }
1731
1732 if (req() > 3 || base == nullptr || !base->is_Phi()) {
1733 return false;
1734 }
1735
1736 if (!mem->is_Phi()) {
1737 if (!MemNode::all_controls_dominate(mem, base->in(0))) {
1738 return false;
1739 }
1740 } else if (base->in(0) != mem->in(0)) {
1741 if (!MemNode::all_controls_dominate(mem, base->in(0))) {
1742 return false;
1743 }
1744 }
1745
1746 return true;
1747 }
1748
1749 //------------------------------split_through_phi------------------------------
1750 // Split instance or boxed field load through Phi.
1751 Node* LoadNode::split_through_phi(PhaseGVN* phase, bool ignore_missing_instance_id) {
1752 if (req() > 3) {
1753 assert(is_LoadVector() && Opcode() != Op_LoadVector, "load has too many inputs");
1754 // LoadVector subclasses such as LoadVectorMasked have extra inputs that the logic below doesn't take into account
1755 return nullptr;
1756 }
1757 Node* mem = in(Memory);
1758 Node* address = in(Address);
1759 const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr();
1760
1761 assert((t_oop != nullptr) &&
1762 (ignore_missing_instance_id ||
1763 t_oop->is_known_instance_field() ||
1764 t_oop->is_ptr_to_boxed_value()), "invalid conditions");
1765
1766 Compile* C = phase->C;
1767 intptr_t ignore = 0;
1768 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1769 bool base_is_phi = (base != nullptr) && base->is_Phi();
1770 bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() &&
1771 (base != nullptr) && (base == address->in(AddPNode::Base)) &&
1772 phase->type(base)->higher_equal(TypePtr::NOTNULL);
1773
1774 if (!((mem->is_Phi() || base_is_phi) &&
1775 (ignore_missing_instance_id || load_boxed_values || t_oop->is_known_instance_field()))) {
1776 return nullptr; // Neither memory or base are Phi
1777 }
1778
1779 if (mem->is_Phi()) {
1780 if (!stable_phi(mem->as_Phi(), phase)) {
1781 return nullptr; // Wait stable graph
1782 }
1783 uint cnt = mem->req();
1784 // Check for loop invariant memory.
1785 if (cnt == 3) {
1786 for (uint i = 1; i < cnt; i++) {
1787 Node* in = mem->in(i);
1788 Node* m = optimize_memory_chain(in, t_oop, this, phase);
1789 if (m == mem) {
1790 if (i == 1) {
1791 // if the first edge was a loop, check second edge too.
1792 // If both are replaceable - we are in an infinite loop
1793 Node *n = optimize_memory_chain(mem->in(2), t_oop, this, phase);
1794 if (n == mem) {
1795 break;
1796 }
1797 }
1798 set_req(Memory, mem->in(cnt - i));
1799 return this; // made change
1800 }
1801 }
1802 }
1803 }
1804 if (base_is_phi) {
1805 if (!stable_phi(base->as_Phi(), phase)) {
1806 return nullptr; // Wait stable graph
1807 }
1808 uint cnt = base->req();
1809 // Check for loop invariant memory.
1810 if (cnt == 3) {
1811 for (uint i = 1; i < cnt; i++) {
1812 if (base->in(i) == base) {
1813 return nullptr; // Wait stable graph
1814 }
1815 }
1816 }
1817 }
1818
1819 // Split through Phi (see original code in loopopts.cpp).
1820 assert(ignore_missing_instance_id || C->have_alias_type(t_oop), "instance should have alias type");
1821
1822 // Do nothing here if Identity will find a value
1823 // (to avoid infinite chain of value phis generation).
1824 if (this != Identity(phase)) {
1825 return nullptr;
1826 }
1827
1828 // Select Region to split through.
1829 Node* region;
1830 DomResult dom_result = DomResult::Dominate;
1831 if (!base_is_phi) {
1832 assert(mem->is_Phi(), "sanity");
1833 region = mem->in(0);
1834 // Skip if the region dominates some control edge of the address.
1835 // We will check `dom_result` later.
1836 dom_result = MemNode::maybe_all_controls_dominate(address, region);
1837 } else if (!mem->is_Phi()) {
1838 assert(base_is_phi, "sanity");
1839 region = base->in(0);
1840 // Skip if the region dominates some control edge of the memory.
1841 // We will check `dom_result` later.
1842 dom_result = MemNode::maybe_all_controls_dominate(mem, region);
1843 } else if (base->in(0) != mem->in(0)) {
1844 assert(base_is_phi && mem->is_Phi(), "sanity");
1845 dom_result = MemNode::maybe_all_controls_dominate(mem, base->in(0));
1846 if (dom_result == DomResult::Dominate) {
1847 region = base->in(0);
1848 } else {
1849 dom_result = MemNode::maybe_all_controls_dominate(address, mem->in(0));
1850 if (dom_result == DomResult::Dominate) {
1851 region = mem->in(0);
1852 }
1853 // Otherwise we encountered a complex graph.
1854 }
1855 } else {
1856 assert(base->in(0) == mem->in(0), "sanity");
1857 region = mem->in(0);
1858 }
1859
1860 PhaseIterGVN* igvn = phase->is_IterGVN();
1861 if (dom_result != DomResult::Dominate) {
1862 if (dom_result == DomResult::EncounteredDeadCode) {
1863 // There is some dead code which eventually will be removed in IGVN.
1864 // Once this is the case, we get an unambiguous dominance result.
1865 // Push the node to the worklist again until the dead code is removed.
1866 igvn->_worklist.push(this);
1867 }
1868 return nullptr;
1869 }
1870
1871 Node* phi = nullptr;
1872 const Type* this_type = this->bottom_type();
1873 if (t_oop != nullptr && (t_oop->is_known_instance_field() || load_boxed_values)) {
1874 int this_index = C->get_alias_index(t_oop);
1875 int this_offset = t_oop->offset();
1876 int this_iid = t_oop->is_known_instance_field() ? t_oop->instance_id() : base->_idx;
1877 phi = new PhiNode(region, this_type, nullptr, mem->_idx, this_iid, this_index, this_offset);
1878 } else if (ignore_missing_instance_id) {
1879 phi = new PhiNode(region, this_type, nullptr, mem->_idx);
1880 } else {
1881 return nullptr;
1882 }
1883
1884 for (uint i = 1; i < region->req(); i++) {
1885 Node* x;
1886 Node* the_clone = nullptr;
1887 Node* in = region->in(i);
1888 if (region->is_CountedLoop() && region->as_Loop()->is_strip_mined() && i == LoopNode::EntryControl &&
1889 in != nullptr && in->is_OuterStripMinedLoop()) {
1890 // No node should go in the outer strip mined loop
1891 in = in->in(LoopNode::EntryControl);
1892 }
1893 if (in == nullptr || in == C->top()) {
1894 x = C->top(); // Dead path? Use a dead data op
1895 } else {
1896 x = this->clone(); // Else clone up the data op
1897 the_clone = x; // Remember for possible deletion.
1898 // Alter data node to use pre-phi inputs
1899 if (this->in(0) == region) {
1900 x->set_req(0, in);
1901 } else {
1902 x->set_req(0, nullptr);
1903 }
1904 if (mem->is_Phi() && (mem->in(0) == region)) {
1905 x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone.
1906 }
1907 if (address->is_Phi() && address->in(0) == region) {
1908 x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone
1909 }
1910 if (base_is_phi && (base->in(0) == region)) {
1911 Node* base_x = base->in(i); // Clone address for loads from boxed objects.
1912 Node* adr_x = phase->transform(new AddPNode(base_x,base_x,address->in(AddPNode::Offset)));
1913 x->set_req(Address, adr_x);
1914 }
1915 }
1916 // Check for a 'win' on some paths
1917 const Type *t = x->Value(igvn);
1918
1919 bool singleton = t->singleton();
1920
1921 // See comments in PhaseIdealLoop::split_thru_phi().
1922 if (singleton && t == Type::TOP) {
1923 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1924 }
1925
1926 if (singleton) {
1927 x = igvn->makecon(t);
1928 } else {
1929 // We now call Identity to try to simplify the cloned node.
1930 // Note that some Identity methods call phase->type(this).
1931 // Make sure that the type array is big enough for
1932 // our new node, even though we may throw the node away.
1933 // (This tweaking with igvn only works because x is a new node.)
1934 igvn->set_type(x, t);
1935 // If x is a TypeNode, capture any more-precise type permanently into Node
1936 // otherwise it will be not updated during igvn->transform since
1937 // igvn->type(x) is set to x->Value() already.
1938 x->raise_bottom_type(t);
1939 Node* y = x->Identity(igvn);
1940 if (y != x) {
1941 x = y;
1942 } else {
1943 y = igvn->hash_find_insert(x);
1944 if (y) {
1945 x = y;
1946 } else {
1947 // Else x is a new node we are keeping
1948 // We do not need register_new_node_with_optimizer
1949 // because set_type has already been called.
1950 igvn->_worklist.push(x);
1951 }
1952 }
1953 }
1954 if (x != the_clone && the_clone != nullptr) {
1955 igvn->remove_dead_node(the_clone);
1956 }
1957 phi->set_req(i, x);
1958 }
1959 // Record Phi
1960 igvn->register_new_node_with_optimizer(phi);
1961 return phi;
1962 }
1963
1964 AllocateNode* LoadNode::is_new_object_mark_load() const {
1965 if (Opcode() == Op_LoadX) {
1966 Node* address = in(MemNode::Address);
1967 AllocateNode* alloc = AllocateNode::Ideal_allocation(address);
1968 Node* mem = in(MemNode::Memory);
1969 if (alloc != nullptr && mem->is_Proj() &&
1970 mem->in(0) != nullptr &&
1971 mem->in(0) == alloc->initialization() &&
1972 alloc->initialization()->proj_out_or_null(0) != nullptr) {
1973 return alloc;
1974 }
1975 }
1976 return nullptr;
1977 }
1978
1979
1980 //------------------------------Ideal------------------------------------------
1981 // If the load is from Field memory and the pointer is non-null, it might be possible to
1982 // zero out the control input.
1983 // If the offset is constant and the base is an object allocation,
1984 // try to hook me up to the exact initializing store.
1985 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1986 if (has_pinned_control_dependency()) {
1987 return nullptr;
1988 }
1989 Node* p = MemNode::Ideal_common(phase, can_reshape);
1990 if (p) return (p == NodeSentinel) ? nullptr : p;
1991
1992 Node* ctrl = in(MemNode::Control);
1993 Node* address = in(MemNode::Address);
1994 bool progress = false;
1995
1996 bool addr_mark = ((phase->type(address)->isa_oopptr() || phase->type(address)->isa_narrowoop()) &&
1997 phase->type(address)->is_ptr()->offset() == oopDesc::mark_offset_in_bytes());
1998
1999 // Skip up past a SafePoint control. Cannot do this for Stores because
2000 // pointer stores & cardmarks must stay on the same side of a SafePoint.
2001 if( ctrl != nullptr && ctrl->Opcode() == Op_SafePoint &&
2002 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw &&
2003 !addr_mark &&
2004 (depends_only_on_test() || has_unknown_control_dependency())) {
2005 ctrl = ctrl->in(0);
2006 set_req(MemNode::Control,ctrl);
2007 progress = true;
2008 }
2009
2010 intptr_t ignore = 0;
2011 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
2012 if (base != nullptr
2013 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
2014 // Check for useless control edge in some common special cases
2015 if (in(MemNode::Control) != nullptr
2016 && !(phase->type(address)->is_inlinetypeptr() && is_mismatched_access())
2017 && can_remove_control()
2018 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
2019 && all_controls_dominate(base, phase->C->start())) {
2020 // A method-invariant, non-null address (constant or 'this' argument).
2021 set_req(MemNode::Control, nullptr);
2022 progress = true;
2023 }
2024 }
2025
2026 Node* mem = in(MemNode::Memory);
2027 const TypePtr *addr_t = phase->type(address)->isa_ptr();
2028
2029 if (can_reshape && (addr_t != nullptr)) {
2030 // try to optimize our memory input
2031 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase);
2032 if (opt_mem != mem) {
2033 set_req_X(MemNode::Memory, opt_mem, phase);
2034 if (phase->type( opt_mem ) == Type::TOP) return nullptr;
2035 return this;
2036 }
2037 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
2038 if ((t_oop != nullptr) &&
2039 (t_oop->is_known_instance_field() ||
2040 t_oop->is_ptr_to_boxed_value())) {
2041 PhaseIterGVN *igvn = phase->is_IterGVN();
2042 assert(igvn != nullptr, "must be PhaseIterGVN when can_reshape is true");
2043 if (igvn->_worklist.member(opt_mem)) {
2044 // Delay this transformation until memory Phi is processed.
2045 igvn->_worklist.push(this);
2046 return nullptr;
2047 }
2048 // Split instance field load through Phi.
2049 Node* result = split_through_phi(phase);
2050 if (result != nullptr) return result;
2051
2052 if (t_oop->is_ptr_to_boxed_value()) {
2053 Node* result = eliminate_autobox(igvn);
2054 if (result != nullptr) return result;
2055 }
2056 }
2057 }
2058
2059 // Is there a dominating load that loads the same value? Leave
2060 // anything that is not a load of a field/array element (like
2061 // barriers etc.) alone
2062 if (in(0) != nullptr && !adr_type()->isa_rawptr() && can_reshape) {
2063 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) {
2064 Node *use = mem->fast_out(i);
2065 if (use != this &&
2066 use->Opcode() == Opcode() &&
2067 use->in(0) != nullptr &&
2068 use->in(0) != in(0) &&
2069 use->in(Address) == in(Address)) {
2070 Node* ctl = in(0);
2071 for (int i = 0; i < 10 && ctl != nullptr; i++) {
2072 ctl = IfNode::up_one_dom(ctl);
2073 if (ctl == use->in(0)) {
2074 set_req(0, use->in(0));
2075 return this;
2076 }
2077 }
2078 }
2079 }
2080 }
2081
2082 // Check for prior store with a different base or offset; make Load
2083 // independent. Skip through any number of them. Bail out if the stores
2084 // are in an endless dead cycle and report no progress. This is a key
2085 // transform for Reflection. However, if after skipping through the Stores
2086 // we can't then fold up against a prior store do NOT do the transform as
2087 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
2088 // array memory alive twice: once for the hoisted Load and again after the
2089 // bypassed Store. This situation only works if EVERYBODY who does
2090 // anti-dependence work knows how to bypass. I.e. we need all
2091 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
2092 // the alias index stuff. So instead, peek through Stores and IFF we can
2093 // fold up, do so.
2094 Node* prev_mem = find_previous_store(phase);
2095 if (prev_mem != nullptr) {
2096 Node* value = can_see_arraycopy_value(prev_mem, phase);
2097 if (value != nullptr) {
2098 return value;
2099 }
2100 }
2101 // Steps (a), (b): Walk past independent stores to find an exact match.
2102 if (prev_mem != nullptr && prev_mem != in(MemNode::Memory)) {
2103 // (c) See if we can fold up on the spot, but don't fold up here.
2104 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
2105 // just return a prior value, which is done by Identity calls.
2106 if (can_see_stored_value(prev_mem, phase)) {
2107 // Make ready for step (d):
2108 set_req_X(MemNode::Memory, prev_mem, phase);
2109 return this;
2110 }
2111 }
2112
2113 if (progress) {
2114 return this;
2115 }
2116
2117 if (!can_reshape) {
2118 phase->record_for_igvn(this);
2119 }
2120 return nullptr;
2121 }
2122
2123 // Helper to recognize certain Klass fields which are invariant across
2124 // some group of array types (e.g., int[] or all T[] where T < Object).
2125 const Type*
2126 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
2127 ciKlass* klass) const {
2128 assert(!UseCompactObjectHeaders || tkls->offset() != in_bytes(Klass::prototype_header_offset()),
2129 "must not happen");
2130 if (tkls->offset() == in_bytes(Klass::access_flags_offset())) {
2131 // The field is Klass::_access_flags. Return its (constant) value.
2132 assert(Opcode() == Op_LoadUS, "must load an unsigned short from _access_flags");
2133 return TypeInt::make(klass->access_flags());
2134 }
2135 if (tkls->offset() == in_bytes(Klass::misc_flags_offset())) {
2136 // The field is Klass::_misc_flags. Return its (constant) value.
2137 assert(Opcode() == Op_LoadUB, "must load an unsigned byte from _misc_flags");
2138 return TypeInt::make(klass->misc_flags());
2139 }
2140 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) {
2141 // The field is Klass::_layout_helper. Return its constant value if known.
2142 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
2143 return TypeInt::make(klass->layout_helper());
2144 }
2145
2146 // No match.
2147 return nullptr;
2148 }
2149
2150 //------------------------------Value-----------------------------------------
2151 const Type* LoadNode::Value(PhaseGVN* phase) const {
2152 // Either input is TOP ==> the result is TOP
2153 Node* mem = in(MemNode::Memory);
2154 const Type *t1 = phase->type(mem);
2155 if (t1 == Type::TOP) return Type::TOP;
2156 Node* adr = in(MemNode::Address);
2157 const TypePtr* tp = phase->type(adr)->isa_ptr();
2158 if (tp == nullptr || tp->empty()) return Type::TOP;
2159 int off = tp->offset();
2160 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
2161 Compile* C = phase->C;
2162
2163 // If we are loading from a freshly-allocated object, produce a zero,
2164 // if the load is provably beyond the header of the object.
2165 // (Also allow a variable load from a fresh array to produce zero.)
2166 const TypeOopPtr* tinst = tp->isa_oopptr();
2167 bool is_instance = (tinst != nullptr) && tinst->is_known_instance_field();
2168 Node* value = can_see_stored_value(mem, phase);
2169 if (value != nullptr && value->is_Con()) {
2170 assert(value->bottom_type()->higher_equal(_type), "sanity");
2171 return value->bottom_type();
2172 }
2173
2174 // Try to guess loaded type from pointer type
2175 if (tp->isa_aryptr()) {
2176 const TypeAryPtr* ary = tp->is_aryptr();
2177 const Type* t = ary->elem();
2178
2179 // Determine whether the reference is beyond the header or not, by comparing
2180 // the offset against the offset of the start of the array's data.
2181 // Different array types begin at slightly different offsets (12 vs. 16).
2182 // We choose T_BYTE as an example base type that is least restrictive
2183 // as to alignment, which will therefore produce the smallest
2184 // possible base offset.
2185 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
2186 const bool off_beyond_header = (off >= min_base_off);
2187
2188 // Try to constant-fold a stable array element.
2189 if (FoldStableValues && !is_mismatched_access() && ary->is_stable()) {
2190 // Make sure the reference is not into the header and the offset is constant
2191 ciObject* aobj = ary->const_oop();
2192 if (aobj != nullptr && off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) {
2193 int stable_dimension = (ary->stable_dimension() > 0 ? ary->stable_dimension() - 1 : 0);
2194 const Type* con_type = Type::make_constant_from_array_element(aobj->as_array(), off,
2195 stable_dimension,
2196 value_basic_type(), is_unsigned());
2197 if (con_type != nullptr) {
2198 return con_type;
2199 }
2200 }
2201 }
2202
2203 // Don't do this for integer types. There is only potential profit if
2204 // the element type t is lower than _type; that is, for int types, if _type is
2205 // more restrictive than t. This only happens here if one is short and the other
2206 // char (both 16 bits), and in those cases we've made an intentional decision
2207 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
2208 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
2209 //
2210 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
2211 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
2212 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
2213 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
2214 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
2215 // In fact, that could have been the original type of p1, and p1 could have
2216 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
2217 // expression (LShiftL quux 3) independently optimized to the constant 8.
2218 if ((t->isa_int() == nullptr) && (t->isa_long() == nullptr)
2219 && (_type->isa_vect() == nullptr)
2220 && !ary->is_flat()
2221 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
2222 // t might actually be lower than _type, if _type is a unique
2223 // concrete subclass of abstract class t.
2224 if (off_beyond_header || off == Type::OffsetBot) { // is the offset beyond the header?
2225 const Type* jt = t->join_speculative(_type);
2226 // In any case, do not allow the join, per se, to empty out the type.
2227 if (jt->empty() && !t->empty()) {
2228 // This can happen if a interface-typed array narrows to a class type.
2229 jt = _type;
2230 }
2231 #ifdef ASSERT
2232 if (phase->C->eliminate_boxing() && adr->is_AddP()) {
2233 // The pointers in the autobox arrays are always non-null
2234 Node* base = adr->in(AddPNode::Base);
2235 if ((base != nullptr) && base->is_DecodeN()) {
2236 // Get LoadN node which loads IntegerCache.cache field
2237 base = base->in(1);
2238 }
2239 if ((base != nullptr) && base->is_Con()) {
2240 const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr();
2241 if ((base_type != nullptr) && base_type->is_autobox_cache()) {
2242 // It could be narrow oop
2243 assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity");
2244 }
2245 }
2246 }
2247 #endif
2248 return jt;
2249 }
2250 }
2251 } else if (tp->base() == Type::InstPtr) {
2252 assert( off != Type::OffsetBot ||
2253 // arrays can be cast to Objects
2254 !tp->isa_instptr() ||
2255 tp->is_instptr()->instance_klass()->is_java_lang_Object() ||
2256 // Default value load
2257 tp->is_instptr()->instance_klass() == ciEnv::current()->Class_klass() ||
2258 // unsafe field access may not have a constant offset
2259 C->has_unsafe_access(),
2260 "Field accesses must be precise" );
2261 // For oop loads, we expect the _type to be precise.
2262
2263 const TypeInstPtr* tinst = tp->is_instptr();
2264 BasicType bt = value_basic_type();
2265
2266 // Optimize loads from constant fields.
2267 ciObject* const_oop = tinst->const_oop();
2268 if (!is_mismatched_access() && off != Type::OffsetBot && const_oop != nullptr && const_oop->is_instance()) {
2269 const Type* con_type = Type::make_constant_from_field(const_oop->as_instance(), off, is_unsigned(), bt);
2270 if (con_type != nullptr) {
2271 return con_type;
2272 }
2273 }
2274 } else if (tp->base() == Type::KlassPtr || tp->base() == Type::InstKlassPtr || tp->base() == Type::AryKlassPtr) {
2275 assert(off != Type::OffsetBot ||
2276 !tp->isa_instklassptr() ||
2277 // arrays can be cast to Objects
2278 tp->isa_instklassptr()->instance_klass()->is_java_lang_Object() ||
2279 // also allow array-loading from the primary supertype
2280 // array during subtype checks
2281 Opcode() == Op_LoadKlass,
2282 "Field accesses must be precise");
2283 // For klass/static loads, we expect the _type to be precise
2284 } else if (tp->base() == Type::RawPtr && adr->is_Load() && off == 0) {
2285 /* With mirrors being an indirect in the Klass*
2286 * the VM is now using two loads. LoadKlass(LoadP(LoadP(Klass, mirror_offset), zero_offset))
2287 * The LoadP from the Klass has a RawPtr type (see LibraryCallKit::load_mirror_from_klass).
2288 *
2289 * So check the type and klass of the node before the LoadP.
2290 */
2291 Node* adr2 = adr->in(MemNode::Address);
2292 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2293 if (tkls != nullptr && !StressReflectiveCode) {
2294 if (tkls->is_loaded() && tkls->klass_is_exact() && tkls->offset() == in_bytes(Klass::java_mirror_offset())) {
2295 ciKlass* klass = tkls->exact_klass();
2296 assert(adr->Opcode() == Op_LoadP, "must load an oop from _java_mirror");
2297 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
2298 return TypeInstPtr::make(klass->java_mirror());
2299 }
2300 }
2301 }
2302
2303 const TypeKlassPtr *tkls = tp->isa_klassptr();
2304 if (tkls != nullptr) {
2305 if (tkls->is_loaded() && tkls->klass_is_exact()) {
2306 ciKlass* klass = tkls->exact_klass();
2307 // We are loading a field from a Klass metaobject whose identity
2308 // is known at compile time (the type is "exact" or "precise").
2309 // Check for fields we know are maintained as constants by the VM.
2310 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) {
2311 // The field is Klass::_super_check_offset. Return its (constant) value.
2312 // (Folds up type checking code.)
2313 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
2314 return TypeInt::make(klass->super_check_offset());
2315 }
2316 if (UseCompactObjectHeaders) { // TODO: Should EnableValhalla also take this path ?
2317 if (tkls->offset() == in_bytes(Klass::prototype_header_offset())) {
2318 // The field is Klass::_prototype_header. Return its (constant) value.
2319 assert(this->Opcode() == Op_LoadX, "must load a proper type from _prototype_header");
2320 return TypeX::make(klass->prototype_header());
2321 }
2322 }
2323 // Compute index into primary_supers array
2324 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
2325 // Check for overflowing; use unsigned compare to handle the negative case.
2326 if( depth < ciKlass::primary_super_limit() ) {
2327 // The field is an element of Klass::_primary_supers. Return its (constant) value.
2328 // (Folds up type checking code.)
2329 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
2330 ciKlass *ss = klass->super_of_depth(depth);
2331 return ss ? TypeKlassPtr::make(ss, Type::trust_interfaces) : TypePtr::NULL_PTR;
2332 }
2333 const Type* aift = load_array_final_field(tkls, klass);
2334 if (aift != nullptr) return aift;
2335 }
2336
2337 // We can still check if we are loading from the primary_supers array at a
2338 // shallow enough depth. Even though the klass is not exact, entries less
2339 // than or equal to its super depth are correct.
2340 if (tkls->is_loaded()) {
2341 ciKlass* klass = nullptr;
2342 if (tkls->isa_instklassptr()) {
2343 klass = tkls->is_instklassptr()->instance_klass();
2344 } else {
2345 int dims;
2346 const Type* inner = tkls->is_aryklassptr()->base_element_type(dims);
2347 if (inner->isa_instklassptr()) {
2348 klass = inner->is_instklassptr()->instance_klass();
2349 klass = ciObjArrayKlass::make(klass, dims);
2350 }
2351 }
2352 if (klass != nullptr) {
2353 // Compute index into primary_supers array
2354 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
2355 // Check for overflowing; use unsigned compare to handle the negative case.
2356 if (depth < ciKlass::primary_super_limit() &&
2357 depth <= klass->super_depth()) { // allow self-depth checks to handle self-check case
2358 // The field is an element of Klass::_primary_supers. Return its (constant) value.
2359 // (Folds up type checking code.)
2360 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
2361 ciKlass *ss = klass->super_of_depth(depth);
2362 return ss ? TypeKlassPtr::make(ss, Type::trust_interfaces) : TypePtr::NULL_PTR;
2363 }
2364 }
2365 }
2366
2367 // If the type is enough to determine that the thing is not an array,
2368 // we can give the layout_helper a positive interval type.
2369 // This will help short-circuit some reflective code.
2370 if (tkls->offset() == in_bytes(Klass::layout_helper_offset()) &&
2371 tkls->isa_instklassptr() && // not directly typed as an array
2372 !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
2373 ) {
2374 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
2375 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
2376 // The key property of this type is that it folds up tests
2377 // for array-ness, since it proves that the layout_helper is positive.
2378 // Thus, a generic value like the basic object layout helper works fine.
2379 return TypeInt::make(min_size, max_jint, Type::WidenMin);
2380 }
2381 }
2382
2383 bool is_vect = (_type->isa_vect() != nullptr);
2384 if (is_instance && !is_vect) {
2385 // If we have an instance type and our memory input is the
2386 // programs's initial memory state, there is no matching store,
2387 // so just return a zero of the appropriate type -
2388 // except if it is vectorized - then we have no zero constant.
2389 Node *mem = in(MemNode::Memory);
2390 if (mem->is_Parm() && mem->in(0)->is_Start()) {
2391 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
2392 // TODO 8350865 Scalar replacement does not work well for flat arrays.
2393 // Escape Analysis assumes that arrays are always zeroed during allocation which is not true for null-free arrays
2394 // ConnectionGraph::split_unique_types will re-wire the memory of loads from such arrays around the allocation
2395 // TestArrays::test6 and test152 and TestBasicFunctionality::test20 are affected by this.
2396 if (tp->isa_aryptr() && tp->is_aryptr()->is_flat() && tp->is_aryptr()->is_null_free()) {
2397 intptr_t offset = 0;
2398 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2399 AllocateNode* alloc = AllocateNode::Ideal_allocation(base);
2400 if (alloc != nullptr && alloc->is_AllocateArray() && alloc->in(AllocateNode::InitValue) != nullptr) {
2401 return _type;
2402 }
2403 }
2404 return Type::get_zero_type(_type->basic_type());
2405 }
2406 }
2407 if (!UseCompactObjectHeaders) {
2408 Node* alloc = is_new_object_mark_load();
2409 if (alloc != nullptr) {
2410 if (EnableValhalla) {
2411 // The mark word may contain property bits (inline, flat, null-free)
2412 Node* klass_node = alloc->in(AllocateNode::KlassNode);
2413 const TypeKlassPtr* tkls = phase->type(klass_node)->isa_klassptr();
2414 if (tkls != nullptr && tkls->is_loaded() && tkls->klass_is_exact()) {
2415 return TypeX::make(tkls->exact_klass()->prototype_header());
2416 }
2417 } else {
2418 return TypeX::make(markWord::prototype().value());
2419 }
2420 }
2421 }
2422
2423 return _type;
2424 }
2425
2426 //------------------------------match_edge-------------------------------------
2427 // Do we Match on this edge index or not? Match only the address.
2428 uint LoadNode::match_edge(uint idx) const {
2429 return idx == MemNode::Address;
2430 }
2431
2432 //--------------------------LoadBNode::Ideal--------------------------------------
2433 //
2434 // If the previous store is to the same address as this load,
2435 // and the value stored was larger than a byte, replace this load
2436 // with the value stored truncated to a byte. If no truncation is
2437 // needed, the replacement is done in LoadNode::Identity().
2438 //
2439 Node* LoadBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2440 Node* mem = in(MemNode::Memory);
2441 Node* value = can_see_stored_value(mem,phase);
2442 if (value != nullptr) {
2443 Node* narrow = Compile::narrow_value(T_BYTE, value, _type, phase, false);
2444 if (narrow != value) {
2445 return narrow;
2446 }
2447 }
2448 // Identity call will handle the case where truncation is not needed.
2449 return LoadNode::Ideal(phase, can_reshape);
2450 }
2451
2452 const Type* LoadBNode::Value(PhaseGVN* phase) const {
2453 Node* mem = in(MemNode::Memory);
2454 Node* value = can_see_stored_value(mem,phase);
2455 if (value != nullptr && value->is_Con() &&
2456 !value->bottom_type()->higher_equal(_type)) {
2457 // If the input to the store does not fit with the load's result type,
2458 // it must be truncated. We can't delay until Ideal call since
2459 // a singleton Value is needed for split_thru_phi optimization.
2460 int con = value->get_int();
2461 return TypeInt::make((con << 24) >> 24);
2462 }
2463 return LoadNode::Value(phase);
2464 }
2465
2466 //--------------------------LoadUBNode::Ideal-------------------------------------
2467 //
2468 // If the previous store is to the same address as this load,
2469 // and the value stored was larger than a byte, replace this load
2470 // with the value stored truncated to a byte. If no truncation is
2471 // needed, the replacement is done in LoadNode::Identity().
2472 //
2473 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2474 Node* mem = in(MemNode::Memory);
2475 Node* value = can_see_stored_value(mem, phase);
2476 if (value != nullptr) {
2477 Node* narrow = Compile::narrow_value(T_BOOLEAN, value, _type, phase, false);
2478 if (narrow != value) {
2479 return narrow;
2480 }
2481 }
2482 // Identity call will handle the case where truncation is not needed.
2483 return LoadNode::Ideal(phase, can_reshape);
2484 }
2485
2486 const Type* LoadUBNode::Value(PhaseGVN* phase) const {
2487 Node* mem = in(MemNode::Memory);
2488 Node* value = can_see_stored_value(mem,phase);
2489 if (value != nullptr && value->is_Con() &&
2490 !value->bottom_type()->higher_equal(_type)) {
2491 // If the input to the store does not fit with the load's result type,
2492 // it must be truncated. We can't delay until Ideal call since
2493 // a singleton Value is needed for split_thru_phi optimization.
2494 int con = value->get_int();
2495 return TypeInt::make(con & 0xFF);
2496 }
2497 return LoadNode::Value(phase);
2498 }
2499
2500 //--------------------------LoadUSNode::Ideal-------------------------------------
2501 //
2502 // If the previous store is to the same address as this load,
2503 // and the value stored was larger than a char, replace this load
2504 // with the value stored truncated to a char. If no truncation is
2505 // needed, the replacement is done in LoadNode::Identity().
2506 //
2507 Node* LoadUSNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2508 Node* mem = in(MemNode::Memory);
2509 Node* value = can_see_stored_value(mem,phase);
2510 if (value != nullptr) {
2511 Node* narrow = Compile::narrow_value(T_CHAR, value, _type, phase, false);
2512 if (narrow != value) {
2513 return narrow;
2514 }
2515 }
2516 // Identity call will handle the case where truncation is not needed.
2517 return LoadNode::Ideal(phase, can_reshape);
2518 }
2519
2520 const Type* LoadUSNode::Value(PhaseGVN* phase) const {
2521 Node* mem = in(MemNode::Memory);
2522 Node* value = can_see_stored_value(mem,phase);
2523 if (value != nullptr && value->is_Con() &&
2524 !value->bottom_type()->higher_equal(_type)) {
2525 // If the input to the store does not fit with the load's result type,
2526 // it must be truncated. We can't delay until Ideal call since
2527 // a singleton Value is needed for split_thru_phi optimization.
2528 int con = value->get_int();
2529 return TypeInt::make(con & 0xFFFF);
2530 }
2531 return LoadNode::Value(phase);
2532 }
2533
2534 //--------------------------LoadSNode::Ideal--------------------------------------
2535 //
2536 // If the previous store is to the same address as this load,
2537 // and the value stored was larger than a short, replace this load
2538 // with the value stored truncated to a short. If no truncation is
2539 // needed, the replacement is done in LoadNode::Identity().
2540 //
2541 Node* LoadSNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2542 Node* mem = in(MemNode::Memory);
2543 Node* value = can_see_stored_value(mem,phase);
2544 if (value != nullptr) {
2545 Node* narrow = Compile::narrow_value(T_SHORT, value, _type, phase, false);
2546 if (narrow != value) {
2547 return narrow;
2548 }
2549 }
2550 // Identity call will handle the case where truncation is not needed.
2551 return LoadNode::Ideal(phase, can_reshape);
2552 }
2553
2554 const Type* LoadSNode::Value(PhaseGVN* phase) const {
2555 Node* mem = in(MemNode::Memory);
2556 Node* value = can_see_stored_value(mem,phase);
2557 if (value != nullptr && value->is_Con() &&
2558 !value->bottom_type()->higher_equal(_type)) {
2559 // If the input to the store does not fit with the load's result type,
2560 // it must be truncated. We can't delay until Ideal call since
2561 // a singleton Value is needed for split_thru_phi optimization.
2562 int con = value->get_int();
2563 return TypeInt::make((con << 16) >> 16);
2564 }
2565 return LoadNode::Value(phase);
2566 }
2567
2568 Node* LoadNNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2569 // Loading from an InlineType, find the input and make an EncodeP
2570 Node* addr = in(Address);
2571 intptr_t offset;
2572 Node* base = AddPNode::Ideal_base_and_offset(addr, phase, offset);
2573 Node* value = see_through_inline_type(phase, this, base, offset);
2574 if (value != nullptr) {
2575 return new EncodePNode(value, type());
2576 }
2577
2578 return LoadNode::Ideal(phase, can_reshape);
2579 }
2580
2581 //=============================================================================
2582 //----------------------------LoadKlassNode::make------------------------------
2583 // Polymorphic factory method:
2584 Node* LoadKlassNode::make(PhaseGVN& gvn, Node* mem, Node* adr, const TypePtr* at, const TypeKlassPtr* tk) {
2585 // sanity check the alias category against the created node type
2586 const TypePtr* adr_type = adr->bottom_type()->isa_ptr();
2587 assert(adr_type != nullptr, "expecting TypeKlassPtr");
2588 #ifdef _LP64
2589 if (adr_type->is_ptr_to_narrowklass()) {
2590 assert(UseCompressedClassPointers, "no compressed klasses");
2591 Node* load_klass = gvn.transform(new LoadNKlassNode(mem, adr, at, tk->make_narrowklass(), MemNode::unordered));
2592 return new DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr());
2593 }
2594 #endif
2595 assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
2596 return new LoadKlassNode(mem, adr, at, tk, MemNode::unordered);
2597 }
2598
2599 //------------------------------Value------------------------------------------
2600 const Type* LoadKlassNode::Value(PhaseGVN* phase) const {
2601 return klass_value_common(phase);
2602 }
2603
2604 const Type* LoadNode::klass_value_common(PhaseGVN* phase) const {
2605 // Either input is TOP ==> the result is TOP
2606 const Type *t1 = phase->type( in(MemNode::Memory) );
2607 if (t1 == Type::TOP) return Type::TOP;
2608 Node *adr = in(MemNode::Address);
2609 const Type *t2 = phase->type( adr );
2610 if (t2 == Type::TOP) return Type::TOP;
2611 const TypePtr *tp = t2->is_ptr();
2612 if (TypePtr::above_centerline(tp->ptr()) ||
2613 tp->ptr() == TypePtr::Null) return Type::TOP;
2614
2615 // Return a more precise klass, if possible
2616 const TypeInstPtr *tinst = tp->isa_instptr();
2617 if (tinst != nullptr) {
2618 ciInstanceKlass* ik = tinst->instance_klass();
2619 int offset = tinst->offset();
2620 if (ik == phase->C->env()->Class_klass()
2621 && (offset == java_lang_Class::klass_offset() ||
2622 offset == java_lang_Class::array_klass_offset())) {
2623 // We are loading a special hidden field from a Class mirror object,
2624 // the field which points to the VM's Klass metaobject.
2625 ciType* t = tinst->java_mirror_type();
2626 // java_mirror_type returns non-null for compile-time Class constants.
2627 if (t != nullptr) {
2628 // constant oop => constant klass
2629 if (offset == java_lang_Class::array_klass_offset()) {
2630 if (t->is_void()) {
2631 // We cannot create a void array. Since void is a primitive type return null
2632 // klass. Users of this result need to do a null check on the returned klass.
2633 return TypePtr::NULL_PTR;
2634 }
2635 return TypeKlassPtr::make(ciArrayKlass::make(t), Type::trust_interfaces);
2636 }
2637 if (!t->is_klass()) {
2638 // a primitive Class (e.g., int.class) has null for a klass field
2639 return TypePtr::NULL_PTR;
2640 }
2641 // Fold up the load of the hidden field
2642 return TypeKlassPtr::make(t->as_klass(), Type::trust_interfaces);
2643 }
2644 // non-constant mirror, so we can't tell what's going on
2645 }
2646 if (!tinst->is_loaded())
2647 return _type; // Bail out if not loaded
2648 if (offset == oopDesc::klass_offset_in_bytes()) {
2649 return tinst->as_klass_type(true);
2650 }
2651 }
2652
2653 // Check for loading klass from an array
2654 const TypeAryPtr* tary = tp->isa_aryptr();
2655 if (tary != nullptr &&
2656 tary->offset() == oopDesc::klass_offset_in_bytes()) {
2657 return tary->as_klass_type(true);
2658 }
2659
2660 // Check for loading klass from an array klass
2661 const TypeKlassPtr *tkls = tp->isa_klassptr();
2662 if (tkls != nullptr && !StressReflectiveCode) {
2663 if (!tkls->is_loaded())
2664 return _type; // Bail out if not loaded
2665 if (tkls->isa_aryklassptr() && tkls->is_aryklassptr()->elem()->isa_klassptr() &&
2666 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) {
2667 // // Always returning precise element type is incorrect,
2668 // // e.g., element type could be object and array may contain strings
2669 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
2670
2671 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
2672 // according to the element type's subclassing.
2673 return tkls->is_aryklassptr()->elem()->isa_klassptr()->cast_to_exactness(tkls->klass_is_exact());
2674 }
2675 if (tkls->isa_instklassptr() != nullptr && tkls->klass_is_exact() &&
2676 tkls->offset() == in_bytes(Klass::super_offset())) {
2677 ciKlass* sup = tkls->is_instklassptr()->instance_klass()->super();
2678 // The field is Klass::_super. Return its (constant) value.
2679 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
2680 return sup ? TypeKlassPtr::make(sup, Type::trust_interfaces) : TypePtr::NULL_PTR;
2681 }
2682 }
2683
2684 if (tkls != nullptr && !UseSecondarySupersCache
2685 && tkls->offset() == in_bytes(Klass::secondary_super_cache_offset())) {
2686 // Treat Klass::_secondary_super_cache as a constant when the cache is disabled.
2687 return TypePtr::NULL_PTR;
2688 }
2689
2690 // Bailout case
2691 return LoadNode::Value(phase);
2692 }
2693
2694 //------------------------------Identity---------------------------------------
2695 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
2696 // Also feed through the klass in Allocate(...klass...)._klass.
2697 Node* LoadKlassNode::Identity(PhaseGVN* phase) {
2698 return klass_identity_common(phase);
2699 }
2700
2701 Node* LoadNode::klass_identity_common(PhaseGVN* phase) {
2702 Node* x = LoadNode::Identity(phase);
2703 if (x != this) return x;
2704
2705 // Take apart the address into an oop and offset.
2706 // Return 'this' if we cannot.
2707 Node* adr = in(MemNode::Address);
2708 intptr_t offset = 0;
2709 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2710 if (base == nullptr) return this;
2711 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
2712 if (toop == nullptr) return this;
2713
2714 // Step over potential GC barrier for OopHandle resolve
2715 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
2716 if (bs->is_gc_barrier_node(base)) {
2717 base = bs->step_over_gc_barrier(base);
2718 }
2719
2720 // We can fetch the klass directly through an AllocateNode.
2721 // This works even if the klass is not constant (clone or newArray).
2722 if (offset == oopDesc::klass_offset_in_bytes()) {
2723 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
2724 if (allocated_klass != nullptr) {
2725 return allocated_klass;
2726 }
2727 }
2728
2729 // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*.
2730 // See inline_native_Class_query for occurrences of these patterns.
2731 // Java Example: x.getClass().isAssignableFrom(y)
2732 //
2733 // This improves reflective code, often making the Class
2734 // mirror go completely dead. (Current exception: Class
2735 // mirrors may appear in debug info, but we could clean them out by
2736 // introducing a new debug info operator for Klass.java_mirror).
2737
2738 if (toop->isa_instptr() && toop->is_instptr()->instance_klass() == phase->C->env()->Class_klass()
2739 && offset == java_lang_Class::klass_offset()) {
2740 if (base->is_Load()) {
2741 Node* base2 = base->in(MemNode::Address);
2742 if (base2->is_Load()) { /* direct load of a load which is the OopHandle */
2743 Node* adr2 = base2->in(MemNode::Address);
2744 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2745 // TODO 8366668 Re-enable this for arrays
2746 if (tkls != nullptr && !tkls->empty()
2747 && ((tkls->isa_instklassptr() && !tkls->is_instklassptr()->might_be_an_array()) || (tkls->isa_aryklassptr() && false))
2748 && adr2->is_AddP()
2749 ) {
2750 int mirror_field = in_bytes(Klass::java_mirror_offset());
2751 if (tkls->offset() == mirror_field) {
2752 return adr2->in(AddPNode::Base);
2753 }
2754 }
2755 }
2756 }
2757 }
2758
2759 return this;
2760 }
2761
2762 LoadNode* LoadNode::clone_pinned() const {
2763 LoadNode* ld = clone()->as_Load();
2764 ld->_control_dependency = UnknownControl;
2765 return ld;
2766 }
2767
2768
2769 //------------------------------Value------------------------------------------
2770 const Type* LoadNKlassNode::Value(PhaseGVN* phase) const {
2771 const Type *t = klass_value_common(phase);
2772 if (t == Type::TOP)
2773 return t;
2774
2775 return t->make_narrowklass();
2776 }
2777
2778 //------------------------------Identity---------------------------------------
2779 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
2780 // Also feed through the klass in Allocate(...klass...)._klass.
2781 Node* LoadNKlassNode::Identity(PhaseGVN* phase) {
2782 Node *x = klass_identity_common(phase);
2783
2784 const Type *t = phase->type( x );
2785 if( t == Type::TOP ) return x;
2786 if( t->isa_narrowklass()) return x;
2787 assert (!t->isa_narrowoop(), "no narrow oop here");
2788
2789 return phase->transform(new EncodePKlassNode(x, t->make_narrowklass()));
2790 }
2791
2792 //------------------------------Value-----------------------------------------
2793 const Type* LoadRangeNode::Value(PhaseGVN* phase) const {
2794 // Either input is TOP ==> the result is TOP
2795 const Type *t1 = phase->type( in(MemNode::Memory) );
2796 if( t1 == Type::TOP ) return Type::TOP;
2797 Node *adr = in(MemNode::Address);
2798 const Type *t2 = phase->type( adr );
2799 if( t2 == Type::TOP ) return Type::TOP;
2800 const TypePtr *tp = t2->is_ptr();
2801 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
2802 const TypeAryPtr *tap = tp->isa_aryptr();
2803 if( !tap ) return _type;
2804 return tap->size();
2805 }
2806
2807 //-------------------------------Ideal---------------------------------------
2808 // Feed through the length in AllocateArray(...length...)._length.
2809 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2810 Node* p = MemNode::Ideal_common(phase, can_reshape);
2811 if (p) return (p == NodeSentinel) ? nullptr : p;
2812
2813 // Take apart the address into an oop and offset.
2814 // Return 'this' if we cannot.
2815 Node* adr = in(MemNode::Address);
2816 intptr_t offset = 0;
2817 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2818 if (base == nullptr) return nullptr;
2819 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2820 if (tary == nullptr) return nullptr;
2821
2822 // We can fetch the length directly through an AllocateArrayNode.
2823 // This works even if the length is not constant (clone or newArray).
2824 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2825 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base);
2826 if (alloc != nullptr) {
2827 Node* allocated_length = alloc->Ideal_length();
2828 Node* len = alloc->make_ideal_length(tary, phase);
2829 if (allocated_length != len) {
2830 // New CastII improves on this.
2831 return len;
2832 }
2833 }
2834 }
2835
2836 return nullptr;
2837 }
2838
2839 //------------------------------Identity---------------------------------------
2840 // Feed through the length in AllocateArray(...length...)._length.
2841 Node* LoadRangeNode::Identity(PhaseGVN* phase) {
2842 Node* x = LoadINode::Identity(phase);
2843 if (x != this) return x;
2844
2845 // Take apart the address into an oop and offset.
2846 // Return 'this' if we cannot.
2847 Node* adr = in(MemNode::Address);
2848 intptr_t offset = 0;
2849 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2850 if (base == nullptr) return this;
2851 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2852 if (tary == nullptr) return this;
2853
2854 // We can fetch the length directly through an AllocateArrayNode.
2855 // This works even if the length is not constant (clone or newArray).
2856 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2857 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base);
2858 if (alloc != nullptr) {
2859 Node* allocated_length = alloc->Ideal_length();
2860 // Do not allow make_ideal_length to allocate a CastII node.
2861 Node* len = alloc->make_ideal_length(tary, phase, false);
2862 if (allocated_length == len) {
2863 // Return allocated_length only if it would not be improved by a CastII.
2864 return allocated_length;
2865 }
2866 }
2867 }
2868
2869 return this;
2870
2871 }
2872
2873 //=============================================================================
2874 //---------------------------StoreNode::make-----------------------------------
2875 // Polymorphic factory method:
2876 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) {
2877 assert((mo == unordered || mo == release), "unexpected");
2878 Compile* C = gvn.C;
2879 assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2880 ctl != nullptr, "raw memory operations should have control edge");
2881
2882 switch (bt) {
2883 case T_BOOLEAN: val = gvn.transform(new AndINode(val, gvn.intcon(0x1))); // Fall through to T_BYTE case
2884 case T_BYTE: return new StoreBNode(ctl, mem, adr, adr_type, val, mo);
2885 case T_INT: return new StoreINode(ctl, mem, adr, adr_type, val, mo);
2886 case T_CHAR:
2887 case T_SHORT: return new StoreCNode(ctl, mem, adr, adr_type, val, mo);
2888 case T_LONG: return new StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic_access);
2889 case T_FLOAT: return new StoreFNode(ctl, mem, adr, adr_type, val, mo);
2890 case T_DOUBLE: return new StoreDNode(ctl, mem, adr, adr_type, val, mo, require_atomic_access);
2891 case T_METADATA:
2892 case T_ADDRESS:
2893 case T_OBJECT:
2894 #ifdef _LP64
2895 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
2896 val = gvn.transform(new EncodePNode(val, val->bottom_type()->make_narrowoop()));
2897 return new StoreNNode(ctl, mem, adr, adr_type, val, mo);
2898 } else if (adr->bottom_type()->is_ptr_to_narrowklass() ||
2899 (UseCompressedClassPointers && val->bottom_type()->isa_klassptr() &&
2900 adr->bottom_type()->isa_rawptr())) {
2901 val = gvn.transform(new EncodePKlassNode(val, val->bottom_type()->make_narrowklass()));
2902 return new StoreNKlassNode(ctl, mem, adr, adr_type, val, mo);
2903 }
2904 #endif
2905 {
2906 return new StorePNode(ctl, mem, adr, adr_type, val, mo);
2907 }
2908 default:
2909 ShouldNotReachHere();
2910 return (StoreNode*)nullptr;
2911 }
2912 }
2913
2914 //--------------------------bottom_type----------------------------------------
2915 const Type *StoreNode::bottom_type() const {
2916 return Type::MEMORY;
2917 }
2918
2919 //------------------------------hash-------------------------------------------
2920 uint StoreNode::hash() const {
2921 // unroll addition of interesting fields
2922 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2923
2924 // Since they are not commoned, do not hash them:
2925 return NO_HASH;
2926 }
2927
2928 // Link together multiple stores (B/S/C/I) into a longer one.
2929 //
2930 // Example: _store = StoreB[i+3]
2931 //
2932 // RangeCheck[i+0] RangeCheck[i+0]
2933 // StoreB[i+0]
2934 // RangeCheck[i+3] RangeCheck[i+3]
2935 // StoreB[i+1] --> pass: fail:
2936 // StoreB[i+2] StoreI[i+0] StoreB[i+0]
2937 // StoreB[i+3]
2938 //
2939 // The 4 StoreB are merged into a single StoreI node. We have to be careful with RangeCheck[i+1]: before
2940 // the optimization, if this RangeCheck[i+1] fails, then we execute only StoreB[i+0], and then trap. After
2941 // the optimization, the new StoreI[i+0] is on the passing path of RangeCheck[i+3], and StoreB[i+0] on the
2942 // failing path.
2943 //
2944 // Note: For normal array stores, every store at first has a RangeCheck. But they can be removed with:
2945 // - RCE (RangeCheck Elimination): the RangeChecks in the loop are hoisted out and before the loop,
2946 // and possibly no RangeChecks remain between the stores.
2947 // - RangeCheck smearing: the earlier RangeChecks are adjusted such that they cover later RangeChecks,
2948 // and those later RangeChecks can be removed. Example:
2949 //
2950 // RangeCheck[i+0] RangeCheck[i+0] <- before first store
2951 // StoreB[i+0] StoreB[i+0] <- first store
2952 // RangeCheck[i+1] --> smeared --> RangeCheck[i+3] <- only RC between first and last store
2953 // StoreB[i+1] StoreB[i+1] <- second store
2954 // RangeCheck[i+2] --> removed
2955 // StoreB[i+2] StoreB[i+2]
2956 // RangeCheck[i+3] --> removed
2957 // StoreB[i+3] StoreB[i+3] <- last store
2958 //
2959 // Thus, it is a common pattern that between the first and last store in a chain
2960 // of adjacent stores there remains exactly one RangeCheck, located between the
2961 // first and the second store (e.g. RangeCheck[i+3]).
2962 //
2963 class MergePrimitiveStores : public StackObj {
2964 private:
2965 PhaseGVN* const _phase;
2966 StoreNode* const _store;
2967 // State machine with initial state Unknown
2968 // Allowed transitions:
2969 // Unknown -> Const
2970 // Unknown -> Platform
2971 // Unknown -> Reverse
2972 // Unknown -> NotAdjacent
2973 // Const -> Const
2974 // Const -> NotAdjacent
2975 // Platform -> Platform
2976 // Platform -> NotAdjacent
2977 // Reverse -> Reverse
2978 // Reverse -> NotAdjacent
2979 // NotAdjacent -> NotAdjacent
2980 enum ValueOrder : uint8_t {
2981 Unknown, // Initial state
2982 Const, // Input values are const
2983 Platform, // Platform order
2984 Reverse, // Reverse platform order
2985 NotAdjacent // Not adjacent
2986 };
2987 ValueOrder _value_order;
2988
2989 NOT_PRODUCT( const CHeapBitMap &_trace_tags; )
2990
2991 public:
2992 MergePrimitiveStores(PhaseGVN* phase, StoreNode* store) :
2993 _phase(phase), _store(store), _value_order(ValueOrder::Unknown)
2994 NOT_PRODUCT( COMMA _trace_tags(Compile::current()->directive()->trace_merge_stores_tags()) )
2995 {}
2996
2997 StoreNode* run();
2998
2999 private:
3000 bool is_compatible_store(const StoreNode* other_store) const;
3001 bool is_adjacent_pair(const StoreNode* use_store, const StoreNode* def_store) const;
3002 bool is_adjacent_input_pair(const Node* n1, const Node* n2, const int memory_size) const;
3003 static bool is_con_RShift(const Node* n, Node const*& base_out, jint& shift_out, PhaseGVN* phase);
3004 enum CFGStatus { SuccessNoRangeCheck, SuccessWithRangeCheck, Failure };
3005 static CFGStatus cfg_status_for_pair(const StoreNode* use_store, const StoreNode* def_store);
3006
3007 class Status {
3008 private:
3009 StoreNode* _found_store;
3010 bool _found_range_check;
3011
3012 Status(StoreNode* found_store, bool found_range_check)
3013 : _found_store(found_store), _found_range_check(found_range_check) {}
3014
3015 public:
3016 StoreNode* found_store() const { return _found_store; }
3017 bool found_range_check() const { return _found_range_check; }
3018 static Status make_failure() { return Status(nullptr, false); }
3019
3020 static Status make(StoreNode* found_store, const CFGStatus cfg_status) {
3021 if (cfg_status == CFGStatus::Failure) {
3022 return Status::make_failure();
3023 }
3024 return Status(found_store, cfg_status == CFGStatus::SuccessWithRangeCheck);
3025 }
3026
3027 #ifndef PRODUCT
3028 void print_on(outputStream* st) const {
3029 if (_found_store == nullptr) {
3030 st->print_cr("None");
3031 } else {
3032 st->print_cr("Found[%d %s, %s]", _found_store->_idx, _found_store->Name(),
3033 _found_range_check ? "RC" : "no-RC");
3034 }
3035 }
3036 #endif
3037 };
3038
3039 enum ValueOrder find_adjacent_input_value_order(const Node* n1, const Node* n2, const int memory_size) const;
3040 Status find_adjacent_use_store(const StoreNode* def_store) const;
3041 Status find_adjacent_def_store(const StoreNode* use_store) const;
3042 Status find_use_store(const StoreNode* def_store) const;
3043 Status find_def_store(const StoreNode* use_store) const;
3044 Status find_use_store_unidirectional(const StoreNode* def_store) const;
3045 Status find_def_store_unidirectional(const StoreNode* use_store) const;
3046
3047 void collect_merge_list(Node_List& merge_list) const;
3048 Node* make_merged_input_value(const Node_List& merge_list);
3049 StoreNode* make_merged_store(const Node_List& merge_list, Node* merged_input_value);
3050
3051 #ifndef PRODUCT
3052 // Access to TraceMergeStores tags
3053 bool is_trace(TraceMergeStores::Tag tag) const {
3054 return _trace_tags.at(tag);
3055 }
3056
3057 bool is_trace_basic() const {
3058 return is_trace(TraceMergeStores::Tag::BASIC);
3059 }
3060
3061 bool is_trace_pointer_parsing() const {
3062 return is_trace(TraceMergeStores::Tag::POINTER_PARSING);
3063 }
3064
3065 bool is_trace_pointer_aliasing() const {
3066 return is_trace(TraceMergeStores::Tag::POINTER_ALIASING);
3067 }
3068
3069 bool is_trace_pointer_adjacency() const {
3070 return is_trace(TraceMergeStores::Tag::POINTER_ADJACENCY);
3071 }
3072
3073 bool is_trace_success() const {
3074 return is_trace(TraceMergeStores::Tag::SUCCESS);
3075 }
3076 #endif
3077
3078 NOT_PRODUCT( void trace(const Node_List& merge_list, const Node* merged_input_value, const StoreNode* merged_store) const; )
3079 };
3080
3081 StoreNode* MergePrimitiveStores::run() {
3082 // Check for B/S/C/I
3083 int opc = _store->Opcode();
3084 if (opc != Op_StoreB && opc != Op_StoreC && opc != Op_StoreI) {
3085 return nullptr;
3086 }
3087
3088 NOT_PRODUCT( if (is_trace_basic()) { tty->print("[TraceMergeStores] MergePrimitiveStores::run: "); _store->dump(); })
3089
3090 // The _store must be the "last" store in a chain. If we find a use we could merge with
3091 // then that use or a store further down is the "last" store.
3092 Status status_use = find_adjacent_use_store(_store);
3093 NOT_PRODUCT( if (is_trace_basic()) { tty->print("[TraceMergeStores] expect no use: "); status_use.print_on(tty); })
3094 if (status_use.found_store() != nullptr) {
3095 return nullptr;
3096 }
3097
3098 // Check if we can merge with at least one def, so that we have at least 2 stores to merge.
3099 Status status_def = find_adjacent_def_store(_store);
3100 NOT_PRODUCT( if (is_trace_basic()) { tty->print("[TraceMergeStores] expect def: "); status_def.print_on(tty); })
3101 Node* def_store = status_def.found_store();
3102 if (def_store == nullptr) {
3103 return nullptr;
3104 }
3105
3106 // Initialize value order
3107 _value_order = find_adjacent_input_value_order(def_store->in(MemNode::ValueIn),
3108 _store->in(MemNode::ValueIn),
3109 _store->memory_size());
3110 assert(_value_order != ValueOrder::NotAdjacent && _value_order != ValueOrder::Unknown, "Order should be checked");
3111
3112 ResourceMark rm;
3113 Node_List merge_list;
3114 collect_merge_list(merge_list);
3115
3116 Node* merged_input_value = make_merged_input_value(merge_list);
3117 if (merged_input_value == nullptr) { return nullptr; }
3118
3119 StoreNode* merged_store = make_merged_store(merge_list, merged_input_value);
3120
3121 NOT_PRODUCT( if (is_trace_success()) { trace(merge_list, merged_input_value, merged_store); } )
3122
3123 return merged_store;
3124 }
3125
3126 // Check compatibility between _store and other_store.
3127 bool MergePrimitiveStores::is_compatible_store(const StoreNode* other_store) const {
3128 int opc = _store->Opcode();
3129 assert(opc == Op_StoreB || opc == Op_StoreC || opc == Op_StoreI, "precondition");
3130
3131 if (other_store == nullptr ||
3132 _store->Opcode() != other_store->Opcode()) {
3133 return false;
3134 }
3135
3136 return true;
3137 }
3138
3139 bool MergePrimitiveStores::is_adjacent_pair(const StoreNode* use_store, const StoreNode* def_store) const {
3140 if (!is_adjacent_input_pair(def_store->in(MemNode::ValueIn),
3141 use_store->in(MemNode::ValueIn),
3142 def_store->memory_size())) {
3143 return false;
3144 }
3145
3146 ResourceMark rm;
3147 #ifndef PRODUCT
3148 const TraceMemPointer trace(is_trace_pointer_parsing(),
3149 is_trace_pointer_aliasing(),
3150 is_trace_pointer_adjacency(),
3151 true);
3152 #endif
3153 const MemPointer pointer_use(use_store NOT_PRODUCT(COMMA trace));
3154 const MemPointer pointer_def(def_store NOT_PRODUCT(COMMA trace));
3155 return pointer_def.is_adjacent_to_and_before(pointer_use);
3156 }
3157
3158 // Check input values n1 and n2 can be merged and return the value order
3159 MergePrimitiveStores::ValueOrder MergePrimitiveStores::find_adjacent_input_value_order(const Node* n1, const Node* n2,
3160 const int memory_size) const {
3161 // Pattern: [n1 = ConI, n2 = ConI]
3162 if (n1->Opcode() == Op_ConI && n2->Opcode() == Op_ConI) {
3163 return ValueOrder::Const;
3164 }
3165
3166 Node const *base_n2;
3167 jint shift_n2;
3168 if (!is_con_RShift(n2, base_n2, shift_n2, _phase)) {
3169 return ValueOrder::NotAdjacent;
3170 }
3171 Node const *base_n1;
3172 jint shift_n1;
3173 if (!is_con_RShift(n1, base_n1, shift_n1, _phase)) {
3174 return ValueOrder::NotAdjacent;
3175 }
3176
3177 int bits_per_store = memory_size * 8;
3178 if (base_n1 != base_n2 ||
3179 abs(shift_n1 - shift_n2) != bits_per_store ||
3180 shift_n1 % bits_per_store != 0) {
3181 // Values are not adjacent
3182 return ValueOrder::NotAdjacent;
3183 }
3184
3185 // Detect value order
3186 #ifdef VM_LITTLE_ENDIAN
3187 return shift_n1 < shift_n2 ? ValueOrder::Platform // Pattern: [n1 = base >> shift, n2 = base >> (shift + memory_size)]
3188 : ValueOrder::Reverse; // Pattern: [n1 = base >> (shift + memory_size), n2 = base >> shift]
3189 #else
3190 return shift_n1 > shift_n2 ? ValueOrder::Platform // Pattern: [n1 = base >> (shift + memory_size), n2 = base >> shift]
3191 : ValueOrder::Reverse; // Pattern: [n1 = base >> shift, n2 = base >> (shift + memory_size)]
3192 #endif
3193 }
3194
3195 bool MergePrimitiveStores::is_adjacent_input_pair(const Node* n1, const Node* n2, const int memory_size) const {
3196 ValueOrder input_value_order = find_adjacent_input_value_order(n1, n2, memory_size);
3197
3198 switch (input_value_order) {
3199 case ValueOrder::NotAdjacent:
3200 return false;
3201 case ValueOrder::Reverse:
3202 if (memory_size != 1 ||
3203 !Matcher::match_rule_supported(Op_ReverseBytesS) ||
3204 !Matcher::match_rule_supported(Op_ReverseBytesI) ||
3205 !Matcher::match_rule_supported(Op_ReverseBytesL)) {
3206 // ReverseBytes are not supported by platform
3207 return false;
3208 }
3209 // fall-through.
3210 case ValueOrder::Const:
3211 case ValueOrder::Platform:
3212 if (_value_order == ValueOrder::Unknown) {
3213 // Initial state is Unknown, and we find a valid input value order
3214 return true;
3215 }
3216 // The value order can not be changed
3217 return _value_order == input_value_order;
3218 case ValueOrder::Unknown:
3219 default:
3220 ShouldNotReachHere();
3221 }
3222 return false;
3223 }
3224
3225 // Detect pattern: n = base_out >> shift_out
3226 bool MergePrimitiveStores::is_con_RShift(const Node* n, Node const*& base_out, jint& shift_out, PhaseGVN* phase) {
3227 assert(n != nullptr, "precondition");
3228
3229 int opc = n->Opcode();
3230 if (opc == Op_ConvL2I) {
3231 n = n->in(1);
3232 opc = n->Opcode();
3233 }
3234
3235 if ((opc == Op_RShiftI ||
3236 opc == Op_RShiftL ||
3237 opc == Op_URShiftI ||
3238 opc == Op_URShiftL) &&
3239 n->in(2)->is_ConI()) {
3240 base_out = n->in(1);
3241 shift_out = n->in(2)->get_int();
3242 // The shift must be positive:
3243 return shift_out >= 0;
3244 }
3245
3246 if (phase->type(n)->isa_int() != nullptr ||
3247 phase->type(n)->isa_long() != nullptr) {
3248 // (base >> 0)
3249 base_out = n;
3250 shift_out = 0;
3251 return true;
3252 }
3253 return false;
3254 }
3255
3256 // Check if there is nothing between the two stores, except optionally a RangeCheck leading to an uncommon trap.
3257 MergePrimitiveStores::CFGStatus MergePrimitiveStores::cfg_status_for_pair(const StoreNode* use_store, const StoreNode* def_store) {
3258 assert(use_store->in(MemNode::Memory) == def_store, "use-def relationship");
3259
3260 Node* ctrl_use = use_store->in(MemNode::Control);
3261 Node* ctrl_def = def_store->in(MemNode::Control);
3262 if (ctrl_use == nullptr || ctrl_def == nullptr) {
3263 return CFGStatus::Failure;
3264 }
3265
3266 if (ctrl_use == ctrl_def) {
3267 // Same ctrl -> no RangeCheck in between.
3268 // Check: use_store must be the only use of def_store.
3269 if (def_store->outcnt() > 1) {
3270 return CFGStatus::Failure;
3271 }
3272 return CFGStatus::SuccessNoRangeCheck;
3273 }
3274
3275 // Different ctrl -> could have RangeCheck in between.
3276 // Check: 1. def_store only has these uses: use_store and MergeMem for uncommon trap, and
3277 // 2. ctrl separated by RangeCheck.
3278 if (def_store->outcnt() != 2) {
3279 return CFGStatus::Failure; // Cannot have exactly these uses: use_store and MergeMem for uncommon trap.
3280 }
3281 int use_store_out_idx = def_store->raw_out(0) == use_store ? 0 : 1;
3282 Node* merge_mem = def_store->raw_out(1 - use_store_out_idx)->isa_MergeMem();
3283 if (merge_mem == nullptr ||
3284 merge_mem->outcnt() != 1) {
3285 return CFGStatus::Failure; // Does not have MergeMem for uncommon trap.
3286 }
3287 if (!ctrl_use->is_IfProj() ||
3288 !ctrl_use->in(0)->is_RangeCheck() ||
3289 ctrl_use->in(0)->outcnt() != 2) {
3290 return CFGStatus::Failure; // Not RangeCheck.
3291 }
3292 ProjNode* other_proj = ctrl_use->as_IfProj()->other_if_proj();
3293 Node* trap = other_proj->is_uncommon_trap_proj(Deoptimization::Reason_range_check);
3294 if (trap != merge_mem->unique_out() ||
3295 ctrl_use->in(0)->in(0) != ctrl_def) {
3296 return CFGStatus::Failure; // Not RangeCheck with merge_mem leading to uncommon trap.
3297 }
3298
3299 return CFGStatus::SuccessWithRangeCheck;
3300 }
3301
3302 MergePrimitiveStores::Status MergePrimitiveStores::find_adjacent_use_store(const StoreNode* def_store) const {
3303 Status status_use = find_use_store(def_store);
3304 StoreNode* use_store = status_use.found_store();
3305 if (use_store != nullptr && !is_adjacent_pair(use_store, def_store)) {
3306 return Status::make_failure();
3307 }
3308 return status_use;
3309 }
3310
3311 MergePrimitiveStores::Status MergePrimitiveStores::find_adjacent_def_store(const StoreNode* use_store) const {
3312 Status status_def = find_def_store(use_store);
3313 StoreNode* def_store = status_def.found_store();
3314 if (def_store != nullptr && !is_adjacent_pair(use_store, def_store)) {
3315 return Status::make_failure();
3316 }
3317 return status_def;
3318 }
3319
3320 MergePrimitiveStores::Status MergePrimitiveStores::find_use_store(const StoreNode* def_store) const {
3321 Status status_use = find_use_store_unidirectional(def_store);
3322
3323 #ifdef ASSERT
3324 StoreNode* use_store = status_use.found_store();
3325 if (use_store != nullptr) {
3326 Status status_def = find_def_store_unidirectional(use_store);
3327 assert(status_def.found_store() == def_store &&
3328 status_def.found_range_check() == status_use.found_range_check(),
3329 "find_use_store and find_def_store must be symmetric");
3330 }
3331 #endif
3332
3333 return status_use;
3334 }
3335
3336 MergePrimitiveStores::Status MergePrimitiveStores::find_def_store(const StoreNode* use_store) const {
3337 Status status_def = find_def_store_unidirectional(use_store);
3338
3339 #ifdef ASSERT
3340 StoreNode* def_store = status_def.found_store();
3341 if (def_store != nullptr) {
3342 Status status_use = find_use_store_unidirectional(def_store);
3343 assert(status_use.found_store() == use_store &&
3344 status_use.found_range_check() == status_def.found_range_check(),
3345 "find_use_store and find_def_store must be symmetric");
3346 }
3347 #endif
3348
3349 return status_def;
3350 }
3351
3352 MergePrimitiveStores::Status MergePrimitiveStores::find_use_store_unidirectional(const StoreNode* def_store) const {
3353 assert(is_compatible_store(def_store), "precondition: must be compatible with _store");
3354
3355 for (DUIterator_Fast imax, i = def_store->fast_outs(imax); i < imax; i++) {
3356 StoreNode* use_store = def_store->fast_out(i)->isa_Store();
3357 if (is_compatible_store(use_store)) {
3358 return Status::make(use_store, cfg_status_for_pair(use_store, def_store));
3359 }
3360 }
3361
3362 return Status::make_failure();
3363 }
3364
3365 MergePrimitiveStores::Status MergePrimitiveStores::find_def_store_unidirectional(const StoreNode* use_store) const {
3366 assert(is_compatible_store(use_store), "precondition: must be compatible with _store");
3367
3368 StoreNode* def_store = use_store->in(MemNode::Memory)->isa_Store();
3369 if (!is_compatible_store(def_store)) {
3370 return Status::make_failure();
3371 }
3372
3373 return Status::make(def_store, cfg_status_for_pair(use_store, def_store));
3374 }
3375
3376 void MergePrimitiveStores::collect_merge_list(Node_List& merge_list) const {
3377 // The merged store can be at most 8 bytes.
3378 const uint merge_list_max_size = 8 / _store->memory_size();
3379 assert(merge_list_max_size >= 2 &&
3380 merge_list_max_size <= 8 &&
3381 is_power_of_2(merge_list_max_size),
3382 "must be 2, 4 or 8");
3383
3384 // Traverse up the chain of adjacent def stores.
3385 StoreNode* current = _store;
3386 merge_list.push(current);
3387 while (current != nullptr && merge_list.size() < merge_list_max_size) {
3388 Status status = find_adjacent_def_store(current);
3389 NOT_PRODUCT( if (is_trace_basic()) { tty->print("[TraceMergeStores] find def: "); status.print_on(tty); })
3390
3391 current = status.found_store();
3392 if (current != nullptr) {
3393 merge_list.push(current);
3394
3395 // We can have at most one RangeCheck.
3396 if (status.found_range_check()) {
3397 NOT_PRODUCT( if (is_trace_basic()) { tty->print_cr("[TraceMergeStores] found RangeCheck, stop traversal."); })
3398 break;
3399 }
3400 }
3401 }
3402
3403 NOT_PRODUCT( if (is_trace_basic()) { tty->print_cr("[TraceMergeStores] found:"); merge_list.dump(); })
3404
3405 // Truncate the merge_list to a power of 2.
3406 const uint pow2size = round_down_power_of_2(merge_list.size());
3407 assert(pow2size >= 2, "must be merging at least 2 stores");
3408 while (merge_list.size() > pow2size) { merge_list.pop(); }
3409
3410 NOT_PRODUCT( if (is_trace_basic()) { tty->print_cr("[TraceMergeStores] truncated:"); merge_list.dump(); })
3411 }
3412
3413 // Merge the input values of the smaller stores to a single larger input value.
3414 Node* MergePrimitiveStores::make_merged_input_value(const Node_List& merge_list) {
3415 int new_memory_size = _store->memory_size() * merge_list.size();
3416 Node* first = merge_list.at(merge_list.size()-1);
3417 Node* merged_input_value = nullptr;
3418 if (_store->in(MemNode::ValueIn)->Opcode() == Op_ConI) {
3419 assert(_value_order == ValueOrder::Const, "must match");
3420 // Pattern: [ConI, ConI, ...] -> new constant
3421 jlong con = 0;
3422 jlong bits_per_store = _store->memory_size() * 8;
3423 jlong mask = (((jlong)1) << bits_per_store) - 1;
3424 for (uint i = 0; i < merge_list.size(); i++) {
3425 jlong con_i = merge_list.at(i)->in(MemNode::ValueIn)->get_int();
3426 #ifdef VM_LITTLE_ENDIAN
3427 con = con << bits_per_store;
3428 con = con | (mask & con_i);
3429 #else // VM_LITTLE_ENDIAN
3430 con_i = (mask & con_i) << (i * bits_per_store);
3431 con = con | con_i;
3432 #endif // VM_LITTLE_ENDIAN
3433 }
3434 merged_input_value = _phase->longcon(con);
3435 } else {
3436 assert(_value_order == ValueOrder::Platform || _value_order == ValueOrder::Reverse, "must match");
3437 // Pattern: [base >> 24, base >> 16, base >> 8, base] -> base
3438 // | |
3439 // _store first
3440 //
3441 Node* hi = _store->in(MemNode::ValueIn);
3442 Node* lo = first->in(MemNode::ValueIn);
3443 #ifndef VM_LITTLE_ENDIAN
3444 // `_store` and `first` are swapped in the diagram above
3445 swap(hi, lo);
3446 #endif // !VM_LITTLE_ENDIAN
3447 if (_value_order == ValueOrder::Reverse) {
3448 swap(hi, lo);
3449 }
3450 Node const* hi_base;
3451 jint hi_shift;
3452 merged_input_value = lo;
3453 bool is_true = is_con_RShift(hi, hi_base, hi_shift, _phase);
3454 assert(is_true, "must detect con RShift");
3455 if (merged_input_value != hi_base && merged_input_value->Opcode() == Op_ConvL2I) {
3456 // look through
3457 merged_input_value = merged_input_value->in(1);
3458 }
3459 if (merged_input_value != hi_base) {
3460 // merged_input_value is not the base
3461 return nullptr;
3462 }
3463 }
3464
3465 if (_phase->type(merged_input_value)->isa_long() != nullptr && new_memory_size <= 4) {
3466 // Example:
3467 //
3468 // long base = ...;
3469 // a[0] = (byte)(base >> 0);
3470 // a[1] = (byte)(base >> 8);
3471 //
3472 merged_input_value = _phase->transform(new ConvL2INode(merged_input_value));
3473 }
3474
3475 assert((_phase->type(merged_input_value)->isa_int() != nullptr && new_memory_size <= 4) ||
3476 (_phase->type(merged_input_value)->isa_long() != nullptr && new_memory_size == 8),
3477 "merged_input_value is either int or long, and new_memory_size is small enough");
3478
3479 if (_value_order == ValueOrder::Reverse) {
3480 assert(_store->memory_size() == 1, "only implemented for bytes");
3481 if (new_memory_size == 8) {
3482 merged_input_value = _phase->transform(new ReverseBytesLNode(merged_input_value));
3483 } else if (new_memory_size == 4) {
3484 merged_input_value = _phase->transform(new ReverseBytesINode(merged_input_value));
3485 } else {
3486 assert(new_memory_size == 2, "sanity check");
3487 merged_input_value = _phase->transform(new ReverseBytesSNode(merged_input_value));
3488 }
3489 }
3490 return merged_input_value;
3491 }
3492
3493 // //
3494 // first_ctrl first_mem first_adr first_ctrl first_mem first_adr //
3495 // | | | | | | //
3496 // | | | | +---------------+ | //
3497 // | | | | | | | //
3498 // | | +---------+ | | +---------------+ //
3499 // | | | | | | | | //
3500 // +--------------+ | | v1 +------------------------------+ | | v1 //
3501 // | | | | | | | | | | | | //
3502 // RangeCheck first_store RangeCheck | | first_store //
3503 // | | | | | | | //
3504 // last_ctrl | +----> unc_trap last_ctrl | | +----> unc_trap //
3505 // | | ===> | | | //
3506 // +--------------+ | a2 v2 | | | //
3507 // | | | | | | | | //
3508 // | second_store | | | //
3509 // | | | | | [v1 v2 ... vn] //
3510 // ... ... | | | | //
3511 // | | | | | v //
3512 // +--------------+ | an vn +--------------+ | | merged_input_value //
3513 // | | | | | | | | //
3514 // last_store (= _store) merged_store //
3515 // //
3516 StoreNode* MergePrimitiveStores::make_merged_store(const Node_List& merge_list, Node* merged_input_value) {
3517 Node* first_store = merge_list.at(merge_list.size()-1);
3518 Node* last_ctrl = _store->in(MemNode::Control); // after (optional) RangeCheck
3519 Node* first_mem = first_store->in(MemNode::Memory);
3520 Node* first_adr = first_store->in(MemNode::Address);
3521
3522 const TypePtr* new_adr_type = _store->adr_type();
3523
3524 int new_memory_size = _store->memory_size() * merge_list.size();
3525 BasicType bt = T_ILLEGAL;
3526 switch (new_memory_size) {
3527 case 2: bt = T_SHORT; break;
3528 case 4: bt = T_INT; break;
3529 case 8: bt = T_LONG; break;
3530 }
3531
3532 StoreNode* merged_store = StoreNode::make(*_phase, last_ctrl, first_mem, first_adr,
3533 new_adr_type, merged_input_value, bt, MemNode::unordered);
3534
3535 // Marking the store mismatched is sufficient to prevent reordering, since array stores
3536 // are all on the same slice. Hence, we need no barriers.
3537 merged_store->set_mismatched_access();
3538
3539 // Constants above may now also be be packed -> put candidate on worklist
3540 _phase->is_IterGVN()->_worklist.push(first_mem);
3541
3542 return merged_store;
3543 }
3544
3545 #ifndef PRODUCT
3546 void MergePrimitiveStores::trace(const Node_List& merge_list, const Node* merged_input_value, const StoreNode* merged_store) const {
3547 stringStream ss;
3548 ss.print_cr("[TraceMergeStores]: Replace");
3549 for (int i = (int)merge_list.size() - 1; i >= 0; i--) {
3550 merge_list.at(i)->dump("\n", false, &ss);
3551 }
3552 ss.print_cr("[TraceMergeStores]: with");
3553 merged_input_value->dump("\n", false, &ss);
3554 merged_store->dump("\n", false, &ss);
3555 tty->print("%s", ss.as_string());
3556 }
3557 #endif
3558
3559 //------------------------------Ideal------------------------------------------
3560 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
3561 // When a store immediately follows a relevant allocation/initialization,
3562 // try to capture it into the initialization, or hoist it above.
3563 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3564 Node* p = MemNode::Ideal_common(phase, can_reshape);
3565 if (p) return (p == NodeSentinel) ? nullptr : p;
3566
3567 Node* mem = in(MemNode::Memory);
3568 Node* address = in(MemNode::Address);
3569 Node* value = in(MemNode::ValueIn);
3570 // Back-to-back stores to same address? Fold em up. Generally
3571 // unsafe if I have intervening uses...
3572 if (phase->C->get_adr_type(phase->C->get_alias_index(adr_type())) != TypeAryPtr::INLINES) {
3573 Node* st = mem;
3574 // If Store 'st' has more than one use, we cannot fold 'st' away.
3575 // For example, 'st' might be the final state at a conditional
3576 // return. Or, 'st' might be used by some node which is live at
3577 // the same time 'st' is live, which might be unschedulable. So,
3578 // require exactly ONE user until such time as we clone 'mem' for
3579 // each of 'mem's uses (thus making the exactly-1-user-rule hold
3580 // true).
3581 while (st->is_Store() && st->outcnt() == 1) {
3582 // Looking at a dead closed cycle of memory?
3583 assert(st != st->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
3584 assert(Opcode() == st->Opcode() ||
3585 st->Opcode() == Op_StoreVector ||
3586 Opcode() == Op_StoreVector ||
3587 st->Opcode() == Op_StoreVectorScatter ||
3588 Opcode() == Op_StoreVectorScatter ||
3589 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw ||
3590 (Opcode() == Op_StoreL && st->Opcode() == Op_StoreI) || // expanded ClearArrayNode
3591 (Opcode() == Op_StoreI && st->Opcode() == Op_StoreL) || // initialization by arraycopy
3592 (Opcode() == Op_StoreL && st->Opcode() == Op_StoreN) ||
3593 (st->adr_type()->isa_aryptr() && st->adr_type()->is_aryptr()->is_flat()) || // TODO 8343835
3594 (is_mismatched_access() || st->as_Store()->is_mismatched_access()),
3595 "no mismatched stores, except on raw memory: %s %s", NodeClassNames[Opcode()], NodeClassNames[st->Opcode()]);
3596
3597 if (st->in(MemNode::Address)->eqv_uncast(address) &&
3598 st->as_Store()->memory_size() <= this->memory_size()) {
3599 Node* use = st->raw_out(0);
3600 if (phase->is_IterGVN()) {
3601 phase->is_IterGVN()->rehash_node_delayed(use);
3602 }
3603 // It's OK to do this in the parser, since DU info is always accurate,
3604 // and the parser always refers to nodes via SafePointNode maps.
3605 use->set_req_X(MemNode::Memory, st->in(MemNode::Memory), phase);
3606 return this;
3607 }
3608 st = st->in(MemNode::Memory);
3609 }
3610 }
3611
3612
3613 // Capture an unaliased, unconditional, simple store into an initializer.
3614 // Or, if it is independent of the allocation, hoist it above the allocation.
3615 if (ReduceFieldZeroing && /*can_reshape &&*/
3616 mem->is_Proj() && mem->in(0)->is_Initialize()) {
3617 InitializeNode* init = mem->in(0)->as_Initialize();
3618 intptr_t offset = init->can_capture_store(this, phase, can_reshape);
3619 if (offset > 0) {
3620 Node* moved = init->capture_store(this, offset, phase, can_reshape);
3621 // If the InitializeNode captured me, it made a raw copy of me,
3622 // and I need to disappear.
3623 if (moved != nullptr) {
3624 // %%% hack to ensure that Ideal returns a new node:
3625 mem = MergeMemNode::make(mem);
3626 return mem; // fold me away
3627 }
3628 }
3629 }
3630
3631 // Fold reinterpret cast into memory operation:
3632 // StoreX mem (MoveY2X v) => StoreY mem v
3633 if (value->is_Move()) {
3634 const Type* vt = value->in(1)->bottom_type();
3635 if (has_reinterpret_variant(vt)) {
3636 if (phase->C->post_loop_opts_phase()) {
3637 return convert_to_reinterpret_store(*phase, value->in(1), vt);
3638 } else {
3639 phase->C->record_for_post_loop_opts_igvn(this); // attempt the transformation once loop opts are over
3640 }
3641 }
3642 }
3643
3644 if (MergeStores && UseUnalignedAccesses) {
3645 if (phase->C->merge_stores_phase()) {
3646 MergePrimitiveStores merge(phase, this);
3647 Node* progress = merge.run();
3648 if (progress != nullptr) { return progress; }
3649 } else {
3650 // We need to wait with merging stores until RangeCheck smearing has removed the RangeChecks during
3651 // the post loops IGVN phase. If we do it earlier, then there may still be some RangeChecks between
3652 // the stores, and we merge the wrong sequence of stores.
3653 // Example:
3654 // StoreI RangeCheck StoreI StoreI RangeCheck StoreI
3655 // Apply MergeStores:
3656 // StoreI RangeCheck [ StoreL ] RangeCheck StoreI
3657 // Remove more RangeChecks:
3658 // StoreI [ StoreL ] StoreI
3659 // But now it would have been better to do this instead:
3660 // [ StoreL ] [ StoreL ]
3661 phase->C->record_for_merge_stores_igvn(this);
3662 }
3663 }
3664
3665 return nullptr; // No further progress
3666 }
3667
3668 //------------------------------Value-----------------------------------------
3669 const Type* StoreNode::Value(PhaseGVN* phase) const {
3670 // Either input is TOP ==> the result is TOP
3671 const Type *t1 = phase->type( in(MemNode::Memory) );
3672 if( t1 == Type::TOP ) return Type::TOP;
3673 const Type *t2 = phase->type( in(MemNode::Address) );
3674 if( t2 == Type::TOP ) return Type::TOP;
3675 const Type *t3 = phase->type( in(MemNode::ValueIn) );
3676 if( t3 == Type::TOP ) return Type::TOP;
3677 return Type::MEMORY;
3678 }
3679
3680 //------------------------------Identity---------------------------------------
3681 // Remove redundant stores:
3682 // Store(m, p, Load(m, p)) changes to m.
3683 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
3684 Node* StoreNode::Identity(PhaseGVN* phase) {
3685 Node* mem = in(MemNode::Memory);
3686 Node* adr = in(MemNode::Address);
3687 Node* val = in(MemNode::ValueIn);
3688
3689 Node* result = this;
3690
3691 // Load then Store? Then the Store is useless
3692 if (val->is_Load() &&
3693 val->in(MemNode::Address)->eqv_uncast(adr) &&
3694 val->in(MemNode::Memory )->eqv_uncast(mem) &&
3695 val->as_Load()->store_Opcode() == Opcode()) {
3696 // Ensure vector type is the same
3697 if (!is_StoreVector() || (mem->is_LoadVector() && as_StoreVector()->vect_type() == mem->as_LoadVector()->vect_type())) {
3698 result = mem;
3699 }
3700 }
3701
3702 // Two stores in a row of the same value?
3703 if (result == this &&
3704 mem->is_Store() &&
3705 mem->in(MemNode::Address)->eqv_uncast(adr) &&
3706 mem->in(MemNode::ValueIn)->eqv_uncast(val) &&
3707 mem->Opcode() == Opcode()) {
3708 if (!is_StoreVector()) {
3709 result = mem;
3710 } else {
3711 const StoreVectorNode* store_vector = as_StoreVector();
3712 const StoreVectorNode* mem_vector = mem->as_StoreVector();
3713 const Node* store_indices = store_vector->indices();
3714 const Node* mem_indices = mem_vector->indices();
3715 const Node* store_mask = store_vector->mask();
3716 const Node* mem_mask = mem_vector->mask();
3717 // Ensure types, indices, and masks match
3718 if (store_vector->vect_type() == mem_vector->vect_type() &&
3719 ((store_indices == nullptr) == (mem_indices == nullptr) &&
3720 (store_indices == nullptr || store_indices->eqv_uncast(mem_indices))) &&
3721 ((store_mask == nullptr) == (mem_mask == nullptr) &&
3722 (store_mask == nullptr || store_mask->eqv_uncast(mem_mask)))) {
3723 result = mem;
3724 }
3725 }
3726 }
3727
3728 // Store of zero anywhere into a freshly-allocated object?
3729 // Then the store is useless.
3730 // (It must already have been captured by the InitializeNode.)
3731 if (result == this && ReduceFieldZeroing) {
3732 // a newly allocated object is already all-zeroes everywhere
3733 if (mem->is_Proj() && mem->in(0)->is_Allocate() &&
3734 (phase->type(val)->is_zero_type() || mem->in(0)->in(AllocateNode::InitValue) == val)) {
3735 result = mem;
3736 }
3737
3738 if (result == this && phase->type(val)->is_zero_type()) {
3739 // the store may also apply to zero-bits in an earlier object
3740 Node* prev_mem = find_previous_store(phase);
3741 // Steps (a), (b): Walk past independent stores to find an exact match.
3742 if (prev_mem != nullptr) {
3743 Node* prev_val = can_see_stored_value(prev_mem, phase);
3744 if (prev_val != nullptr && prev_val == val) {
3745 // prev_val and val might differ by a cast; it would be good
3746 // to keep the more informative of the two.
3747 result = mem;
3748 }
3749 }
3750 }
3751 }
3752
3753 PhaseIterGVN* igvn = phase->is_IterGVN();
3754 if (result != this && igvn != nullptr) {
3755 MemBarNode* trailing = trailing_membar();
3756 if (trailing != nullptr) {
3757 #ifdef ASSERT
3758 const TypeOopPtr* t_oop = phase->type(in(Address))->isa_oopptr();
3759 assert(t_oop == nullptr || t_oop->is_known_instance_field(), "only for non escaping objects");
3760 #endif
3761 trailing->remove(igvn);
3762 }
3763 }
3764
3765 return result;
3766 }
3767
3768 //------------------------------match_edge-------------------------------------
3769 // Do we Match on this edge index or not? Match only memory & value
3770 uint StoreNode::match_edge(uint idx) const {
3771 return idx == MemNode::Address || idx == MemNode::ValueIn;
3772 }
3773
3774 //------------------------------cmp--------------------------------------------
3775 // Do not common stores up together. They generally have to be split
3776 // back up anyways, so do not bother.
3777 bool StoreNode::cmp( const Node &n ) const {
3778 return (&n == this); // Always fail except on self
3779 }
3780
3781 //------------------------------Ideal_masked_input-----------------------------
3782 // Check for a useless mask before a partial-word store
3783 // (StoreB ... (AndI valIn conIa) )
3784 // If (conIa & mask == mask) this simplifies to
3785 // (StoreB ... (valIn) )
3786 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
3787 Node *val = in(MemNode::ValueIn);
3788 if( val->Opcode() == Op_AndI ) {
3789 const TypeInt *t = phase->type( val->in(2) )->isa_int();
3790 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
3791 set_req_X(MemNode::ValueIn, val->in(1), phase);
3792 return this;
3793 }
3794 }
3795 return nullptr;
3796 }
3797
3798
3799 //------------------------------Ideal_sign_extended_input----------------------
3800 // Check for useless sign-extension before a partial-word store
3801 // (StoreB ... (RShiftI _ (LShiftI _ v conIL) conIR))
3802 // If (conIL == conIR && conIR <= num_rejected_bits) this simplifies to
3803 // (StoreB ... (v))
3804 // If (conIL > conIR) under some conditions, it can be simplified into
3805 // (StoreB ... (LShiftI _ v (conIL - conIR)))
3806 // This case happens when the value of the store was itself a left shift, that
3807 // gets merged into the inner left shift of the sign-extension. For instance,
3808 // if we have
3809 // array_of_shorts[0] = (short)(v << 2)
3810 // We get a structure such as:
3811 // (StoreB ... (RShiftI _ (LShiftI _ (LShiftI _ v 2) 16) 16))
3812 // that is simplified into
3813 // (StoreB ... (RShiftI _ (LShiftI _ v 18) 16)).
3814 // It is thus useful to handle cases where conIL > conIR. But this simplification
3815 // does not always hold. Let's see in which cases it's valid.
3816 //
3817 // Let's assume we have the following 32 bits integer v:
3818 // +----------------------------------+
3819 // | v[0..31] |
3820 // +----------------------------------+
3821 // 31 0
3822 // that will be stuffed in 8 bits byte after a shift left and a shift right of
3823 // potentially different magnitudes.
3824 // We denote num_rejected_bits the number of bits of the discarded part. In this
3825 // case, num_rejected_bits == 24.
3826 //
3827 // Statement (proved further below in case analysis):
3828 // Given:
3829 // - 0 <= conIL < BitsPerJavaInteger (no wrap in shift, enforced by maskShiftAmount)
3830 // - 0 <= conIR < BitsPerJavaInteger (no wrap in shift, enforced by maskShiftAmount)
3831 // - conIL >= conIR
3832 // - num_rejected_bits >= conIR
3833 // Then this form:
3834 // (RShiftI _ (LShiftI _ v conIL) conIR)
3835 // can be replaced with this form:
3836 // (LShiftI _ v (conIL-conIR))
3837 //
3838 // Note: We only have to show that the non-rejected lowest bits (8 bits for byte)
3839 // have to be correct, as the higher bits are rejected / truncated by the store.
3840 //
3841 // The hypotheses
3842 // 0 <= conIL < BitsPerJavaInteger
3843 // 0 <= conIR < BitsPerJavaInteger
3844 // are ensured by maskShiftAmount (called from ::Ideal of shift nodes). Indeed,
3845 // (v << 31) << 2 must be simplified into 0, not into v << 33 (which is equivalent
3846 // to v << 1).
3847 //
3848 //
3849 // If you don't like case analysis, jump after the conclusion.
3850 // ### Case 1 : conIL == conIR
3851 // ###### Case 1.1: conIL == conIR == num_rejected_bits
3852 // If we do the shift left then right by 24 bits, we get:
3853 // after: v << 24
3854 // +---------+------------------------+
3855 // | v[0..7] | 0 |
3856 // +---------+------------------------+
3857 // 31 24 23 0
3858 // after: (v << 24) >> 24
3859 // +------------------------+---------+
3860 // | sign bit | v[0..7] |
3861 // +------------------------+---------+
3862 // 31 8 7 0
3863 // The non-rejected bits (bits kept by the store, that is the 8 lower bits of the
3864 // result) are the same before and after, so, indeed, simplifying is correct.
3865
3866 // ###### Case 1.2: conIL == conIR < num_rejected_bits
3867 // If we do the shift left then right by 22 bits, we get:
3868 // after: v << 22
3869 // +---------+------------------------+
3870 // | v[0..9] | 0 |
3871 // +---------+------------------------+
3872 // 31 22 21 0
3873 // after: (v << 22) >> 22
3874 // +------------------------+---------+
3875 // | sign bit | v[0..9] |
3876 // +------------------------+---------+
3877 // 31 10 9 0
3878 // The non-rejected bits are the 8 lower bits of v. The bits 8 and 9 of v are still
3879 // present in (v << 22) >> 22 but will be dropped by the store. The simplification is
3880 // still correct.
3881
3882 // ###### But! Case 1.3: conIL == conIR > num_rejected_bits
3883 // If we do the shift left then right by 26 bits, we get:
3884 // after: v << 26
3885 // +---------+------------------------+
3886 // | v[0..5] | 0 |
3887 // +---------+------------------------+
3888 // 31 26 25 0
3889 // after: (v << 26) >> 26
3890 // +------------------------+---------+
3891 // | sign bit | v[0..5] |
3892 // +------------------------+---------+
3893 // 31 6 5 0
3894 // The non-rejected bits are made of
3895 // - 0-5 => the bits 0 to 5 of v
3896 // - 6-7 => the sign bit of v[0..5] (that is v[5])
3897 // Simplifying this as v is not correct.
3898 // The condition conIR <= num_rejected_bits is indeed necessary in Case 1
3899 //
3900 // ### Case 2: conIL > conIR
3901 // ###### Case 2.1: num_rejected_bits == conIR
3902 // We take conIL == 26 for this example.
3903 // after: v << 26
3904 // +---------+------------------------+
3905 // | v[0..5] | 0 |
3906 // +---------+------------------------+
3907 // 31 26 25 0
3908 // after: (v << 26) >> 24
3909 // +------------------+---------+-----+
3910 // | sign bit | v[0..5] | 0 |
3911 // +------------------+---------+-----+
3912 // 31 8 7 2 1 0
3913 // The non-rejected bits are the 8 lower ones of (v << conIL - conIR).
3914 // The bits 6 and 7 of v have been thrown away after the shift left.
3915 // The simplification is still correct.
3916 //
3917 // ###### Case 2.2: num_rejected_bits > conIR.
3918 // Let's say conIL == 26 and conIR == 22.
3919 // after: v << 26
3920 // +---------+------------------------+
3921 // | v[0..5] | 0 |
3922 // +---------+------------------------+
3923 // 31 26 25 0
3924 // after: (v << 26) >> 22
3925 // +------------------+---------+-----+
3926 // | sign bit | v[0..5] | 0 |
3927 // +------------------+---------+-----+
3928 // 31 10 9 4 3 0
3929 // The bits non-rejected by the store are exactly the 8 lower ones of (v << (conIL - conIR)):
3930 // - 0-3 => 0
3931 // - 4-7 => bits 0 to 3 of v
3932 // The simplification is still correct.
3933 // The bits 4 and 5 of v are still present in (v << (conIL - conIR)) but they don't
3934 // matter as they are not in the 8 lower bits: they will be cut out by the store.
3935 //
3936 // ###### But! Case 2.3: num_rejected_bits < conIR.
3937 // Let's see that this case is not as easy to simplify.
3938 // Let's say conIL == 28 and conIR == 26.
3939 // after: v << 28
3940 // +---------+------------------------+
3941 // | v[0..3] | 0 |
3942 // +---------+------------------------+
3943 // 31 28 27 0
3944 // after: (v << 28) >> 26
3945 // +------------------+---------+-----+
3946 // | sign bit | v[0..3] | 0 |
3947 // +------------------+---------+-----+
3948 // 31 6 5 2 1 0
3949 // The non-rejected bits are made of
3950 // - 0-1 => 0
3951 // - 2-5 => the bits 0 to 3 of v
3952 // - 6-7 => the sign bit of v[0..3] (that is v[3])
3953 // Simplifying this as (v << 2) is not correct.
3954 // The condition conIR <= num_rejected_bits is indeed necessary in Case 2.
3955 //
3956 // ### Conclusion:
3957 // Our hypotheses are indeed sufficient:
3958 // - 0 <= conIL < BitsPerJavaInteger
3959 // - 0 <= conIR < BitsPerJavaInteger
3960 // - conIL >= conIR
3961 // - num_rejected_bits >= conIR
3962 //
3963 // ### A rationale without case analysis:
3964 // After the shift left, conIL upper bits of v are discarded and conIL lower bit
3965 // zeroes are added. After the shift right, conIR lower bits of the previous result
3966 // are discarded. If conIL >= conIR, we discard only the zeroes we made up during
3967 // the shift left, but if conIL < conIR, then we discard also lower bits of v. But
3968 // the point of the simplification is to get an expression of the form
3969 // (v << (conIL - conIR)). This expression discard only higher bits of v, thus the
3970 // simplification is not correct if conIL < conIR.
3971 //
3972 // Moreover, after the shift right, the higher bit of (v << conIL) is repeated on the
3973 // conIR higher bits of ((v << conIL) >> conIR), it's the sign-extension. If
3974 // conIR > num_rejected_bits, then at least one artificial copy of this sign bit will
3975 // be in the window of the store. Thus ((v << conIL) >> conIR) is not equivalent to
3976 // (v << (conIL-conIR)) if conIR > num_rejected_bits.
3977 //
3978 // We do not treat the case conIL < conIR here since the point of this function is
3979 // to skip sign-extensions (that is conIL == conIR == num_rejected_bits). The need
3980 // of treating conIL > conIR comes from the cases where the sign-extended value is
3981 // also left-shift expression. Computing the sign-extension of a right-shift expression
3982 // doesn't yield a situation such as
3983 // (StoreB ... (RShiftI _ (LShiftI _ v conIL) conIR))
3984 // where conIL < conIR.
3985 Node* StoreNode::Ideal_sign_extended_input(PhaseGVN* phase, int num_rejected_bits) {
3986 Node* shr = in(MemNode::ValueIn);
3987 if (shr->Opcode() == Op_RShiftI) {
3988 const TypeInt* conIR = phase->type(shr->in(2))->isa_int();
3989 if (conIR != nullptr && conIR->is_con() && conIR->get_con() >= 0 && conIR->get_con() < BitsPerJavaInteger && conIR->get_con() <= num_rejected_bits) {
3990 Node* shl = shr->in(1);
3991 if (shl->Opcode() == Op_LShiftI) {
3992 const TypeInt* conIL = phase->type(shl->in(2))->isa_int();
3993 if (conIL != nullptr && conIL->is_con() && conIL->get_con() >= 0 && conIL->get_con() < BitsPerJavaInteger) {
3994 if (conIL->get_con() == conIR->get_con()) {
3995 set_req_X(MemNode::ValueIn, shl->in(1), phase);
3996 return this;
3997 }
3998 if (conIL->get_con() > conIR->get_con()) {
3999 Node* new_shl = phase->transform(new LShiftINode(shl->in(1), phase->intcon(conIL->get_con() - conIR->get_con())));
4000 set_req_X(MemNode::ValueIn, new_shl, phase);
4001 return this;
4002 }
4003 }
4004 }
4005 }
4006 }
4007 return nullptr;
4008 }
4009
4010 //------------------------------value_never_loaded-----------------------------------
4011 // Determine whether there are any possible loads of the value stored.
4012 // For simplicity, we actually check if there are any loads from the
4013 // address stored to, not just for loads of the value stored by this node.
4014 //
4015 bool StoreNode::value_never_loaded(PhaseValues* phase) const {
4016 Node *adr = in(Address);
4017 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
4018 if (adr_oop == nullptr)
4019 return false;
4020 if (!adr_oop->is_known_instance_field())
4021 return false; // if not a distinct instance, there may be aliases of the address
4022 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
4023 Node *use = adr->fast_out(i);
4024 if (use->is_Load() || use->is_LoadStore()) {
4025 return false;
4026 }
4027 }
4028 return true;
4029 }
4030
4031 MemBarNode* StoreNode::trailing_membar() const {
4032 if (is_release()) {
4033 MemBarNode* trailing_mb = nullptr;
4034 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
4035 Node* u = fast_out(i);
4036 if (u->is_MemBar()) {
4037 if (u->as_MemBar()->trailing_store()) {
4038 assert(u->Opcode() == Op_MemBarVolatile, "");
4039 assert(trailing_mb == nullptr, "only one");
4040 trailing_mb = u->as_MemBar();
4041 #ifdef ASSERT
4042 Node* leading = u->as_MemBar()->leading_membar();
4043 assert(leading->Opcode() == Op_MemBarRelease, "incorrect membar");
4044 assert(leading->as_MemBar()->leading_store(), "incorrect membar pair");
4045 assert(leading->as_MemBar()->trailing_membar() == u, "incorrect membar pair");
4046 #endif
4047 } else {
4048 assert(u->as_MemBar()->standalone(), "");
4049 }
4050 }
4051 }
4052 return trailing_mb;
4053 }
4054 return nullptr;
4055 }
4056
4057
4058 //=============================================================================
4059 //------------------------------Ideal------------------------------------------
4060 // If the store is from an AND mask that leaves the low bits untouched, then
4061 // we can skip the AND operation. If the store is from a sign-extension
4062 // (a left shift, then right shift) we can skip both.
4063 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
4064 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
4065 if( progress != nullptr ) return progress;
4066
4067 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
4068 if( progress != nullptr ) return progress;
4069
4070 // Finally check the default case
4071 return StoreNode::Ideal(phase, can_reshape);
4072 }
4073
4074 //=============================================================================
4075 //------------------------------Ideal------------------------------------------
4076 // If the store is from an AND mask that leaves the low bits untouched, then
4077 // we can skip the AND operation
4078 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
4079 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
4080 if( progress != nullptr ) return progress;
4081
4082 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
4083 if( progress != nullptr ) return progress;
4084
4085 // Finally check the default case
4086 return StoreNode::Ideal(phase, can_reshape);
4087 }
4088
4089 //=============================================================================
4090 //----------------------------------SCMemProjNode------------------------------
4091 const Type* SCMemProjNode::Value(PhaseGVN* phase) const
4092 {
4093 if (in(0) == nullptr || phase->type(in(0)) == Type::TOP) {
4094 return Type::TOP;
4095 }
4096 return bottom_type();
4097 }
4098
4099 //=============================================================================
4100 //----------------------------------LoadStoreNode------------------------------
4101 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required )
4102 : Node(required),
4103 _type(rt),
4104 _adr_type(at),
4105 _barrier_data(0)
4106 {
4107 init_req(MemNode::Control, c );
4108 init_req(MemNode::Memory , mem);
4109 init_req(MemNode::Address, adr);
4110 init_req(MemNode::ValueIn, val);
4111 init_class_id(Class_LoadStore);
4112 }
4113
4114 //------------------------------Value-----------------------------------------
4115 const Type* LoadStoreNode::Value(PhaseGVN* phase) const {
4116 // Either input is TOP ==> the result is TOP
4117 if (!in(MemNode::Control) || phase->type(in(MemNode::Control)) == Type::TOP) {
4118 return Type::TOP;
4119 }
4120 const Type* t = phase->type(in(MemNode::Memory));
4121 if (t == Type::TOP) {
4122 return Type::TOP;
4123 }
4124 t = phase->type(in(MemNode::Address));
4125 if (t == Type::TOP) {
4126 return Type::TOP;
4127 }
4128 t = phase->type(in(MemNode::ValueIn));
4129 if (t == Type::TOP) {
4130 return Type::TOP;
4131 }
4132 return bottom_type();
4133 }
4134
4135 uint LoadStoreNode::ideal_reg() const {
4136 return _type->ideal_reg();
4137 }
4138
4139 // This method conservatively checks if the result of a LoadStoreNode is
4140 // used, that is, if it returns true, then it is definitely the case that
4141 // the result of the node is not needed.
4142 // For example, GetAndAdd can be matched into a lock_add instead of a
4143 // lock_xadd if the result of LoadStoreNode::result_not_used() is true
4144 bool LoadStoreNode::result_not_used() const {
4145 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
4146 Node *x = fast_out(i);
4147 if (x->Opcode() == Op_SCMemProj) {
4148 continue;
4149 }
4150 if (x->bottom_type() == TypeTuple::MEMBAR &&
4151 !x->is_Call() &&
4152 x->Opcode() != Op_Blackhole) {
4153 continue;
4154 }
4155 return false;
4156 }
4157 return true;
4158 }
4159
4160 MemBarNode* LoadStoreNode::trailing_membar() const {
4161 MemBarNode* trailing = nullptr;
4162 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
4163 Node* u = fast_out(i);
4164 if (u->is_MemBar()) {
4165 if (u->as_MemBar()->trailing_load_store()) {
4166 assert(u->Opcode() == Op_MemBarAcquire, "");
4167 assert(trailing == nullptr, "only one");
4168 trailing = u->as_MemBar();
4169 #ifdef ASSERT
4170 Node* leading = trailing->leading_membar();
4171 assert(support_IRIW_for_not_multiple_copy_atomic_cpu || leading->Opcode() == Op_MemBarRelease, "incorrect membar");
4172 assert(leading->as_MemBar()->leading_load_store(), "incorrect membar pair");
4173 assert(leading->as_MemBar()->trailing_membar() == trailing, "incorrect membar pair");
4174 #endif
4175 } else {
4176 assert(u->as_MemBar()->standalone(), "wrong barrier kind");
4177 }
4178 }
4179 }
4180
4181 return trailing;
4182 }
4183
4184 uint LoadStoreNode::size_of() const { return sizeof(*this); }
4185
4186 //=============================================================================
4187 //----------------------------------LoadStoreConditionalNode--------------------
4188 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, nullptr, TypeInt::BOOL, 5) {
4189 init_req(ExpectedIn, ex );
4190 }
4191
4192 const Type* LoadStoreConditionalNode::Value(PhaseGVN* phase) const {
4193 // Either input is TOP ==> the result is TOP
4194 const Type* t = phase->type(in(ExpectedIn));
4195 if (t == Type::TOP) {
4196 return Type::TOP;
4197 }
4198 return LoadStoreNode::Value(phase);
4199 }
4200
4201 //=============================================================================
4202 //-------------------------------adr_type--------------------------------------
4203 const TypePtr* ClearArrayNode::adr_type() const {
4204 Node *adr = in(3);
4205 if (adr == nullptr) return nullptr; // node is dead
4206 return MemNode::calculate_adr_type(adr->bottom_type());
4207 }
4208
4209 //------------------------------match_edge-------------------------------------
4210 // Do we Match on this edge index or not? Do not match memory
4211 uint ClearArrayNode::match_edge(uint idx) const {
4212 return idx > 1;
4213 }
4214
4215 //------------------------------Identity---------------------------------------
4216 // Clearing a zero length array does nothing
4217 Node* ClearArrayNode::Identity(PhaseGVN* phase) {
4218 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
4219 }
4220
4221 //------------------------------Idealize---------------------------------------
4222 // Clearing a short array is faster with stores
4223 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4224 // Already know this is a large node, do not try to ideal it
4225 if (_is_large) return nullptr;
4226
4227 const int unit = BytesPerLong;
4228 const TypeX* t = phase->type(in(2))->isa_intptr_t();
4229 if (!t) return nullptr;
4230 if (!t->is_con()) return nullptr;
4231 intptr_t raw_count = t->get_con();
4232 intptr_t size = raw_count;
4233 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
4234 // Clearing nothing uses the Identity call.
4235 // Negative clears are possible on dead ClearArrays
4236 // (see jck test stmt114.stmt11402.val).
4237 if (size <= 0 || size % unit != 0) return nullptr;
4238 intptr_t count = size / unit;
4239 // Length too long; communicate this to matchers and assemblers.
4240 // Assemblers are responsible to produce fast hardware clears for it.
4241 if (size > InitArrayShortSize) {
4242 return new ClearArrayNode(in(0), in(1), in(2), in(3), in(4), true);
4243 } else if (size > 2 && Matcher::match_rule_supported_vector(Op_ClearArray, 4, T_LONG)) {
4244 return nullptr;
4245 }
4246 if (!IdealizeClearArrayNode) return nullptr;
4247 Node *mem = in(1);
4248 if( phase->type(mem)==Type::TOP ) return nullptr;
4249 Node *adr = in(3);
4250 const Type* at = phase->type(adr);
4251 if( at==Type::TOP ) return nullptr;
4252 const TypePtr* atp = at->isa_ptr();
4253 // adjust atp to be the correct array element address type
4254 if (atp == nullptr) atp = TypePtr::BOTTOM;
4255 else atp = atp->add_offset(Type::OffsetBot);
4256 // Get base for derived pointer purposes
4257 if( adr->Opcode() != Op_AddP ) Unimplemented();
4258 Node *base = adr->in(1);
4259
4260 Node *val = in(4);
4261 Node *off = phase->MakeConX(BytesPerLong);
4262 mem = new StoreLNode(in(0), mem, adr, atp, val, MemNode::unordered, false);
4263 count--;
4264 while( count-- ) {
4265 mem = phase->transform(mem);
4266 adr = phase->transform(new AddPNode(base,adr,off));
4267 mem = new StoreLNode(in(0), mem, adr, atp, val, MemNode::unordered, false);
4268 }
4269 return mem;
4270 }
4271
4272 //----------------------------step_through----------------------------------
4273 // Return allocation input memory edge if it is different instance
4274 // or itself if it is the one we are looking for.
4275 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseValues* phase) {
4276 Node* n = *np;
4277 assert(n->is_ClearArray(), "sanity");
4278 intptr_t offset;
4279 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
4280 // This method is called only before Allocate nodes are expanded
4281 // during macro nodes expansion. Before that ClearArray nodes are
4282 // only generated in PhaseMacroExpand::generate_arraycopy() (before
4283 // Allocate nodes are expanded) which follows allocations.
4284 assert(alloc != nullptr, "should have allocation");
4285 if (alloc->_idx == instance_id) {
4286 // Can not bypass initialization of the instance we are looking for.
4287 return false;
4288 }
4289 // Otherwise skip it.
4290 InitializeNode* init = alloc->initialization();
4291 if (init != nullptr)
4292 *np = init->in(TypeFunc::Memory);
4293 else
4294 *np = alloc->in(TypeFunc::Memory);
4295 return true;
4296 }
4297
4298 //----------------------------clear_memory-------------------------------------
4299 // Generate code to initialize object storage to zero.
4300 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
4301 Node* val,
4302 Node* raw_val,
4303 intptr_t start_offset,
4304 Node* end_offset,
4305 PhaseGVN* phase) {
4306 intptr_t offset = start_offset;
4307
4308 int unit = BytesPerLong;
4309 if ((offset % unit) != 0) {
4310 Node* adr = new AddPNode(dest, dest, phase->MakeConX(offset));
4311 adr = phase->transform(adr);
4312 const TypePtr* atp = TypeRawPtr::BOTTOM;
4313 if (val != nullptr) {
4314 assert(phase->type(val)->isa_narrowoop(), "should be narrow oop");
4315 mem = new StoreNNode(ctl, mem, adr, atp, val, MemNode::unordered);
4316 } else {
4317 assert(raw_val == nullptr, "val may not be null");
4318 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
4319 }
4320 mem = phase->transform(mem);
4321 offset += BytesPerInt;
4322 }
4323 assert((offset % unit) == 0, "");
4324
4325 // Initialize the remaining stuff, if any, with a ClearArray.
4326 return clear_memory(ctl, mem, dest, raw_val, phase->MakeConX(offset), end_offset, phase);
4327 }
4328
4329 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
4330 Node* raw_val,
4331 Node* start_offset,
4332 Node* end_offset,
4333 PhaseGVN* phase) {
4334 if (start_offset == end_offset) {
4335 // nothing to do
4336 return mem;
4337 }
4338
4339 int unit = BytesPerLong;
4340 Node* zbase = start_offset;
4341 Node* zend = end_offset;
4342
4343 // Scale to the unit required by the CPU:
4344 if (!Matcher::init_array_count_is_in_bytes) {
4345 Node* shift = phase->intcon(exact_log2(unit));
4346 zbase = phase->transform(new URShiftXNode(zbase, shift) );
4347 zend = phase->transform(new URShiftXNode(zend, shift) );
4348 }
4349
4350 // Bulk clear double-words
4351 Node* zsize = phase->transform(new SubXNode(zend, zbase) );
4352 Node* adr = phase->transform(new AddPNode(dest, dest, start_offset) );
4353 if (raw_val == nullptr) {
4354 raw_val = phase->MakeConX(0);
4355 }
4356 mem = new ClearArrayNode(ctl, mem, zsize, adr, raw_val, false);
4357 return phase->transform(mem);
4358 }
4359
4360 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
4361 Node* val,
4362 Node* raw_val,
4363 intptr_t start_offset,
4364 intptr_t end_offset,
4365 PhaseGVN* phase) {
4366 if (start_offset == end_offset) {
4367 // nothing to do
4368 return mem;
4369 }
4370
4371 assert((end_offset % BytesPerInt) == 0, "odd end offset");
4372 intptr_t done_offset = end_offset;
4373 if ((done_offset % BytesPerLong) != 0) {
4374 done_offset -= BytesPerInt;
4375 }
4376 if (done_offset > start_offset) {
4377 mem = clear_memory(ctl, mem, dest, val, raw_val,
4378 start_offset, phase->MakeConX(done_offset), phase);
4379 }
4380 if (done_offset < end_offset) { // emit the final 32-bit store
4381 Node* adr = new AddPNode(dest, dest, phase->MakeConX(done_offset));
4382 adr = phase->transform(adr);
4383 const TypePtr* atp = TypeRawPtr::BOTTOM;
4384 if (val != nullptr) {
4385 assert(phase->type(val)->isa_narrowoop(), "should be narrow oop");
4386 mem = new StoreNNode(ctl, mem, adr, atp, val, MemNode::unordered);
4387 } else {
4388 assert(raw_val == nullptr, "val may not be null");
4389 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
4390 }
4391 mem = phase->transform(mem);
4392 done_offset += BytesPerInt;
4393 }
4394 assert(done_offset == end_offset, "");
4395 return mem;
4396 }
4397
4398 //=============================================================================
4399 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
4400 : MultiNode(TypeFunc::Parms + (precedent == nullptr? 0: 1)),
4401 _adr_type(C->get_adr_type(alias_idx)), _kind(Standalone)
4402 #ifdef ASSERT
4403 , _pair_idx(0)
4404 #endif
4405 {
4406 init_class_id(Class_MemBar);
4407 Node* top = C->top();
4408 init_req(TypeFunc::I_O,top);
4409 init_req(TypeFunc::FramePtr,top);
4410 init_req(TypeFunc::ReturnAdr,top);
4411 if (precedent != nullptr)
4412 init_req(TypeFunc::Parms, precedent);
4413 }
4414
4415 //------------------------------cmp--------------------------------------------
4416 uint MemBarNode::hash() const { return NO_HASH; }
4417 bool MemBarNode::cmp( const Node &n ) const {
4418 return (&n == this); // Always fail except on self
4419 }
4420
4421 //------------------------------make-------------------------------------------
4422 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
4423 switch (opcode) {
4424 case Op_MemBarAcquire: return new MemBarAcquireNode(C, atp, pn);
4425 case Op_LoadFence: return new LoadFenceNode(C, atp, pn);
4426 case Op_MemBarRelease: return new MemBarReleaseNode(C, atp, pn);
4427 case Op_StoreFence: return new StoreFenceNode(C, atp, pn);
4428 case Op_MemBarStoreStore: return new MemBarStoreStoreNode(C, atp, pn);
4429 case Op_StoreStoreFence: return new StoreStoreFenceNode(C, atp, pn);
4430 case Op_MemBarAcquireLock: return new MemBarAcquireLockNode(C, atp, pn);
4431 case Op_MemBarReleaseLock: return new MemBarReleaseLockNode(C, atp, pn);
4432 case Op_MemBarVolatile: return new MemBarVolatileNode(C, atp, pn);
4433 case Op_MemBarCPUOrder: return new MemBarCPUOrderNode(C, atp, pn);
4434 case Op_OnSpinWait: return new OnSpinWaitNode(C, atp, pn);
4435 case Op_Initialize: return new InitializeNode(C, atp, pn);
4436 default: ShouldNotReachHere(); return nullptr;
4437 }
4438 }
4439
4440 void MemBarNode::remove(PhaseIterGVN *igvn) {
4441 if (outcnt() != 2) {
4442 assert(Opcode() == Op_Initialize, "Only seen when there are no use of init memory");
4443 assert(outcnt() == 1, "Only control then");
4444 }
4445 if (trailing_store() || trailing_load_store()) {
4446 MemBarNode* leading = leading_membar();
4447 if (leading != nullptr) {
4448 assert(leading->trailing_membar() == this, "inconsistent leading/trailing membars");
4449 leading->remove(igvn);
4450 }
4451 }
4452 if (proj_out_or_null(TypeFunc::Memory) != nullptr) {
4453 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
4454 }
4455 if (proj_out_or_null(TypeFunc::Control) != nullptr) {
4456 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
4457 }
4458 }
4459
4460 //------------------------------Ideal------------------------------------------
4461 // Return a node which is more "ideal" than the current node. Strip out
4462 // control copies
4463 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4464 if (remove_dead_region(phase, can_reshape)) return this;
4465 // Don't bother trying to transform a dead node
4466 if (in(0) && in(0)->is_top()) {
4467 return nullptr;
4468 }
4469
4470 bool progress = false;
4471 // Eliminate volatile MemBars for scalar replaced objects.
4472 if (can_reshape && req() == (Precedent+1)) {
4473 bool eliminate = false;
4474 int opc = Opcode();
4475 if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) {
4476 // Volatile field loads and stores.
4477 Node* my_mem = in(MemBarNode::Precedent);
4478 // The MembarAquire may keep an unused LoadNode alive through the Precedent edge
4479 if ((my_mem != nullptr) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) {
4480 // if the Precedent is a decodeN and its input (a Load) is used at more than one place,
4481 // replace this Precedent (decodeN) with the Load instead.
4482 if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1)) {
4483 Node* load_node = my_mem->in(1);
4484 set_req(MemBarNode::Precedent, load_node);
4485 phase->is_IterGVN()->_worklist.push(my_mem);
4486 my_mem = load_node;
4487 } else {
4488 assert(my_mem->unique_out() == this, "sanity");
4489 assert(!trailing_load_store(), "load store node can't be eliminated");
4490 del_req(Precedent);
4491 phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later
4492 my_mem = nullptr;
4493 }
4494 progress = true;
4495 }
4496 if (my_mem != nullptr && my_mem->is_Mem()) {
4497 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
4498 // Check for scalar replaced object reference.
4499 if( t_oop != nullptr && t_oop->is_known_instance_field() &&
4500 t_oop->offset() != Type::OffsetBot &&
4501 t_oop->offset() != Type::OffsetTop) {
4502 eliminate = true;
4503 }
4504 }
4505 } else if (opc == Op_MemBarRelease || (UseStoreStoreForCtor && opc == Op_MemBarStoreStore)) {
4506 // Final field stores.
4507 Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent));
4508 if ((alloc != nullptr) && alloc->is_Allocate() &&
4509 alloc->as_Allocate()->does_not_escape_thread()) {
4510 // The allocated object does not escape.
4511 eliminate = true;
4512 }
4513 }
4514 if (eliminate) {
4515 // Replace MemBar projections by its inputs.
4516 PhaseIterGVN* igvn = phase->is_IterGVN();
4517 remove(igvn);
4518 // Must return either the original node (now dead) or a new node
4519 // (Do not return a top here, since that would break the uniqueness of top.)
4520 return new ConINode(TypeInt::ZERO);
4521 }
4522 }
4523 return progress ? this : nullptr;
4524 }
4525
4526 //------------------------------Value------------------------------------------
4527 const Type* MemBarNode::Value(PhaseGVN* phase) const {
4528 if( !in(0) ) return Type::TOP;
4529 if( phase->type(in(0)) == Type::TOP )
4530 return Type::TOP;
4531 return TypeTuple::MEMBAR;
4532 }
4533
4534 //------------------------------match------------------------------------------
4535 // Construct projections for memory.
4536 Node *MemBarNode::match(const ProjNode *proj, const Matcher *m, const RegMask* mask) {
4537 switch (proj->_con) {
4538 case TypeFunc::Control:
4539 case TypeFunc::Memory:
4540 return new MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
4541 }
4542 ShouldNotReachHere();
4543 return nullptr;
4544 }
4545
4546 void MemBarNode::set_store_pair(MemBarNode* leading, MemBarNode* trailing) {
4547 trailing->_kind = TrailingStore;
4548 leading->_kind = LeadingStore;
4549 #ifdef ASSERT
4550 trailing->_pair_idx = leading->_idx;
4551 leading->_pair_idx = leading->_idx;
4552 #endif
4553 }
4554
4555 void MemBarNode::set_load_store_pair(MemBarNode* leading, MemBarNode* trailing) {
4556 trailing->_kind = TrailingLoadStore;
4557 leading->_kind = LeadingLoadStore;
4558 #ifdef ASSERT
4559 trailing->_pair_idx = leading->_idx;
4560 leading->_pair_idx = leading->_idx;
4561 #endif
4562 }
4563
4564 MemBarNode* MemBarNode::trailing_membar() const {
4565 ResourceMark rm;
4566 Node* trailing = (Node*)this;
4567 VectorSet seen;
4568 Node_Stack multis(0);
4569 do {
4570 Node* c = trailing;
4571 uint i = 0;
4572 do {
4573 trailing = nullptr;
4574 for (; i < c->outcnt(); i++) {
4575 Node* next = c->raw_out(i);
4576 if (next != c && next->is_CFG()) {
4577 if (c->is_MultiBranch()) {
4578 if (multis.node() == c) {
4579 multis.set_index(i+1);
4580 } else {
4581 multis.push(c, i+1);
4582 }
4583 }
4584 trailing = next;
4585 break;
4586 }
4587 }
4588 if (trailing != nullptr && !seen.test_set(trailing->_idx)) {
4589 break;
4590 }
4591 while (multis.size() > 0) {
4592 c = multis.node();
4593 i = multis.index();
4594 if (i < c->req()) {
4595 break;
4596 }
4597 multis.pop();
4598 }
4599 } while (multis.size() > 0);
4600 } while (!trailing->is_MemBar() || !trailing->as_MemBar()->trailing());
4601
4602 MemBarNode* mb = trailing->as_MemBar();
4603 assert((mb->_kind == TrailingStore && _kind == LeadingStore) ||
4604 (mb->_kind == TrailingLoadStore && _kind == LeadingLoadStore), "bad trailing membar");
4605 assert(mb->_pair_idx == _pair_idx, "bad trailing membar");
4606 return mb;
4607 }
4608
4609 MemBarNode* MemBarNode::leading_membar() const {
4610 ResourceMark rm;
4611 VectorSet seen;
4612 Node_Stack regions(0);
4613 Node* leading = in(0);
4614 while (leading != nullptr && (!leading->is_MemBar() || !leading->as_MemBar()->leading())) {
4615 while (leading == nullptr || leading->is_top() || seen.test_set(leading->_idx)) {
4616 leading = nullptr;
4617 while (regions.size() > 0 && leading == nullptr) {
4618 Node* r = regions.node();
4619 uint i = regions.index();
4620 if (i < r->req()) {
4621 leading = r->in(i);
4622 regions.set_index(i+1);
4623 } else {
4624 regions.pop();
4625 }
4626 }
4627 if (leading == nullptr) {
4628 assert(regions.size() == 0, "all paths should have been tried");
4629 return nullptr;
4630 }
4631 }
4632 if (leading->is_Region()) {
4633 regions.push(leading, 2);
4634 leading = leading->in(1);
4635 } else {
4636 leading = leading->in(0);
4637 }
4638 }
4639 #ifdef ASSERT
4640 Unique_Node_List wq;
4641 wq.push((Node*)this);
4642 uint found = 0;
4643 for (uint i = 0; i < wq.size(); i++) {
4644 Node* n = wq.at(i);
4645 if (n->is_Region()) {
4646 for (uint j = 1; j < n->req(); j++) {
4647 Node* in = n->in(j);
4648 if (in != nullptr && !in->is_top()) {
4649 wq.push(in);
4650 }
4651 }
4652 } else {
4653 if (n->is_MemBar() && n->as_MemBar()->leading()) {
4654 assert(n == leading, "consistency check failed");
4655 found++;
4656 } else {
4657 Node* in = n->in(0);
4658 if (in != nullptr && !in->is_top()) {
4659 wq.push(in);
4660 }
4661 }
4662 }
4663 }
4664 assert(found == 1 || (found == 0 && leading == nullptr), "consistency check failed");
4665 #endif
4666 if (leading == nullptr) {
4667 return nullptr;
4668 }
4669 MemBarNode* mb = leading->as_MemBar();
4670 assert((mb->_kind == LeadingStore && _kind == TrailingStore) ||
4671 (mb->_kind == LeadingLoadStore && _kind == TrailingLoadStore), "bad leading membar");
4672 assert(mb->_pair_idx == _pair_idx, "bad leading membar");
4673 return mb;
4674 }
4675
4676
4677 //===========================InitializeNode====================================
4678 // SUMMARY:
4679 // This node acts as a memory barrier on raw memory, after some raw stores.
4680 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
4681 // The Initialize can 'capture' suitably constrained stores as raw inits.
4682 // It can coalesce related raw stores into larger units (called 'tiles').
4683 // It can avoid zeroing new storage for memory units which have raw inits.
4684 // At macro-expansion, it is marked 'complete', and does not optimize further.
4685 //
4686 // EXAMPLE:
4687 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
4688 // ctl = incoming control; mem* = incoming memory
4689 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
4690 // First allocate uninitialized memory and fill in the header:
4691 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
4692 // ctl := alloc.Control; mem* := alloc.Memory*
4693 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
4694 // Then initialize to zero the non-header parts of the raw memory block:
4695 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
4696 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
4697 // After the initialize node executes, the object is ready for service:
4698 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
4699 // Suppose its body is immediately initialized as {1,2}:
4700 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
4701 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
4702 // mem.SLICE(#short[*]) := store2
4703 //
4704 // DETAILS:
4705 // An InitializeNode collects and isolates object initialization after
4706 // an AllocateNode and before the next possible safepoint. As a
4707 // memory barrier (MemBarNode), it keeps critical stores from drifting
4708 // down past any safepoint or any publication of the allocation.
4709 // Before this barrier, a newly-allocated object may have uninitialized bits.
4710 // After this barrier, it may be treated as a real oop, and GC is allowed.
4711 //
4712 // The semantics of the InitializeNode include an implicit zeroing of
4713 // the new object from object header to the end of the object.
4714 // (The object header and end are determined by the AllocateNode.)
4715 //
4716 // Certain stores may be added as direct inputs to the InitializeNode.
4717 // These stores must update raw memory, and they must be to addresses
4718 // derived from the raw address produced by AllocateNode, and with
4719 // a constant offset. They must be ordered by increasing offset.
4720 // The first one is at in(RawStores), the last at in(req()-1).
4721 // Unlike most memory operations, they are not linked in a chain,
4722 // but are displayed in parallel as users of the rawmem output of
4723 // the allocation.
4724 //
4725 // (See comments in InitializeNode::capture_store, which continue
4726 // the example given above.)
4727 //
4728 // When the associated Allocate is macro-expanded, the InitializeNode
4729 // may be rewritten to optimize collected stores. A ClearArrayNode
4730 // may also be created at that point to represent any required zeroing.
4731 // The InitializeNode is then marked 'complete', prohibiting further
4732 // capturing of nearby memory operations.
4733 //
4734 // During macro-expansion, all captured initializations which store
4735 // constant values of 32 bits or smaller are coalesced (if advantageous)
4736 // into larger 'tiles' 32 or 64 bits. This allows an object to be
4737 // initialized in fewer memory operations. Memory words which are
4738 // covered by neither tiles nor non-constant stores are pre-zeroed
4739 // by explicit stores of zero. (The code shape happens to do all
4740 // zeroing first, then all other stores, with both sequences occurring
4741 // in order of ascending offsets.)
4742 //
4743 // Alternatively, code may be inserted between an AllocateNode and its
4744 // InitializeNode, to perform arbitrary initialization of the new object.
4745 // E.g., the object copying intrinsics insert complex data transfers here.
4746 // The initialization must then be marked as 'complete' disable the
4747 // built-in zeroing semantics and the collection of initializing stores.
4748 //
4749 // While an InitializeNode is incomplete, reads from the memory state
4750 // produced by it are optimizable if they match the control edge and
4751 // new oop address associated with the allocation/initialization.
4752 // They return a stored value (if the offset matches) or else zero.
4753 // A write to the memory state, if it matches control and address,
4754 // and if it is to a constant offset, may be 'captured' by the
4755 // InitializeNode. It is cloned as a raw memory operation and rewired
4756 // inside the initialization, to the raw oop produced by the allocation.
4757 // Operations on addresses which are provably distinct (e.g., to
4758 // other AllocateNodes) are allowed to bypass the initialization.
4759 //
4760 // The effect of all this is to consolidate object initialization
4761 // (both arrays and non-arrays, both piecewise and bulk) into a
4762 // single location, where it can be optimized as a unit.
4763 //
4764 // Only stores with an offset less than TrackedInitializationLimit words
4765 // will be considered for capture by an InitializeNode. This puts a
4766 // reasonable limit on the complexity of optimized initializations.
4767
4768 //---------------------------InitializeNode------------------------------------
4769 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
4770 : MemBarNode(C, adr_type, rawoop),
4771 _is_complete(Incomplete), _does_not_escape(false)
4772 {
4773 init_class_id(Class_Initialize);
4774
4775 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
4776 assert(in(RawAddress) == rawoop, "proper init");
4777 // Note: allocation() can be null, for secondary initialization barriers
4778 }
4779
4780 // Since this node is not matched, it will be processed by the
4781 // register allocator. Declare that there are no constraints
4782 // on the allocation of the RawAddress edge.
4783 const RegMask &InitializeNode::in_RegMask(uint idx) const {
4784 // This edge should be set to top, by the set_complete. But be conservative.
4785 if (idx == InitializeNode::RawAddress)
4786 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
4787 return RegMask::Empty;
4788 }
4789
4790 Node* InitializeNode::memory(uint alias_idx) {
4791 Node* mem = in(Memory);
4792 if (mem->is_MergeMem()) {
4793 return mem->as_MergeMem()->memory_at(alias_idx);
4794 } else {
4795 // incoming raw memory is not split
4796 return mem;
4797 }
4798 }
4799
4800 bool InitializeNode::is_non_zero() {
4801 if (is_complete()) return false;
4802 remove_extra_zeroes();
4803 return (req() > RawStores);
4804 }
4805
4806 void InitializeNode::set_complete(PhaseGVN* phase) {
4807 assert(!is_complete(), "caller responsibility");
4808 _is_complete = Complete;
4809
4810 // After this node is complete, it contains a bunch of
4811 // raw-memory initializations. There is no need for
4812 // it to have anything to do with non-raw memory effects.
4813 // Therefore, tell all non-raw users to re-optimize themselves,
4814 // after skipping the memory effects of this initialization.
4815 PhaseIterGVN* igvn = phase->is_IterGVN();
4816 if (igvn) igvn->add_users_to_worklist(this);
4817 }
4818
4819 // convenience function
4820 // return false if the init contains any stores already
4821 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
4822 InitializeNode* init = initialization();
4823 if (init == nullptr || init->is_complete()) {
4824 return false;
4825 }
4826 init->remove_extra_zeroes();
4827 // for now, if this allocation has already collected any inits, bail:
4828 if (init->is_non_zero()) return false;
4829 init->set_complete(phase);
4830 return true;
4831 }
4832
4833 void InitializeNode::remove_extra_zeroes() {
4834 if (req() == RawStores) return;
4835 Node* zmem = zero_memory();
4836 uint fill = RawStores;
4837 for (uint i = fill; i < req(); i++) {
4838 Node* n = in(i);
4839 if (n->is_top() || n == zmem) continue; // skip
4840 if (fill < i) set_req(fill, n); // compact
4841 ++fill;
4842 }
4843 // delete any empty spaces created:
4844 while (fill < req()) {
4845 del_req(fill);
4846 }
4847 }
4848
4849 // Helper for remembering which stores go with which offsets.
4850 intptr_t InitializeNode::get_store_offset(Node* st, PhaseValues* phase) {
4851 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
4852 intptr_t offset = -1;
4853 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
4854 phase, offset);
4855 if (base == nullptr) return -1; // something is dead,
4856 if (offset < 0) return -1; // dead, dead
4857 return offset;
4858 }
4859
4860 // Helper for proving that an initialization expression is
4861 // "simple enough" to be folded into an object initialization.
4862 // Attempts to prove that a store's initial value 'n' can be captured
4863 // within the initialization without creating a vicious cycle, such as:
4864 // { Foo p = new Foo(); p.next = p; }
4865 // True for constants and parameters and small combinations thereof.
4866 bool InitializeNode::detect_init_independence(Node* value, PhaseGVN* phase) {
4867 ResourceMark rm;
4868 Unique_Node_List worklist;
4869 worklist.push(value);
4870
4871 uint complexity_limit = 20;
4872 for (uint j = 0; j < worklist.size(); j++) {
4873 if (j >= complexity_limit) {
4874 return false; // Bail out if processed too many nodes
4875 }
4876
4877 Node* n = worklist.at(j);
4878 if (n == nullptr) continue; // (can this really happen?)
4879 if (n->is_Proj()) n = n->in(0);
4880 if (n == this) return false; // found a cycle
4881 if (n->is_Con()) continue;
4882 if (n->is_Start()) continue; // params, etc., are OK
4883 if (n->is_Root()) continue; // even better
4884
4885 // There cannot be any dependency if 'n' is a CFG node that dominates the current allocation
4886 if (n->is_CFG() && phase->is_dominator(n, allocation())) {
4887 continue;
4888 }
4889
4890 Node* ctl = n->in(0);
4891 if (ctl != nullptr && !ctl->is_top()) {
4892 if (ctl->is_Proj()) ctl = ctl->in(0);
4893 if (ctl == this) return false;
4894
4895 // If we already know that the enclosing memory op is pinned right after
4896 // the init, then any control flow that the store has picked up
4897 // must have preceded the init, or else be equal to the init.
4898 // Even after loop optimizations (which might change control edges)
4899 // a store is never pinned *before* the availability of its inputs.
4900 if (!MemNode::all_controls_dominate(n, this)) {
4901 return false; // failed to prove a good control
4902 }
4903 }
4904
4905 // Check data edges for possible dependencies on 'this'.
4906 for (uint i = 1; i < n->req(); i++) {
4907 Node* m = n->in(i);
4908 if (m == nullptr || m == n || m->is_top()) continue;
4909
4910 // Only process data inputs once
4911 worklist.push(m);
4912 }
4913 }
4914
4915 return true;
4916 }
4917
4918 // Here are all the checks a Store must pass before it can be moved into
4919 // an initialization. Returns zero if a check fails.
4920 // On success, returns the (constant) offset to which the store applies,
4921 // within the initialized memory.
4922 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseGVN* phase, bool can_reshape) {
4923 const int FAIL = 0;
4924 if (st->req() != MemNode::ValueIn + 1)
4925 return FAIL; // an inscrutable StoreNode (card mark?)
4926 Node* ctl = st->in(MemNode::Control);
4927 if (!(ctl != nullptr && ctl->is_Proj() && ctl->in(0) == this))
4928 return FAIL; // must be unconditional after the initialization
4929 Node* mem = st->in(MemNode::Memory);
4930 if (!(mem->is_Proj() && mem->in(0) == this))
4931 return FAIL; // must not be preceded by other stores
4932 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
4933 if ((st->Opcode() == Op_StoreP || st->Opcode() == Op_StoreN) &&
4934 !bs->can_initialize_object(st)) {
4935 return FAIL;
4936 }
4937 Node* adr = st->in(MemNode::Address);
4938 intptr_t offset;
4939 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
4940 if (alloc == nullptr)
4941 return FAIL; // inscrutable address
4942 if (alloc != allocation())
4943 return FAIL; // wrong allocation! (store needs to float up)
4944 int size_in_bytes = st->memory_size();
4945 if ((size_in_bytes != 0) && (offset % size_in_bytes) != 0) {
4946 return FAIL; // mismatched access
4947 }
4948 Node* val = st->in(MemNode::ValueIn);
4949
4950 if (!detect_init_independence(val, phase))
4951 return FAIL; // stored value must be 'simple enough'
4952
4953 // The Store can be captured only if nothing after the allocation
4954 // and before the Store is using the memory location that the store
4955 // overwrites.
4956 bool failed = false;
4957 // If is_complete_with_arraycopy() is true the shape of the graph is
4958 // well defined and is safe so no need for extra checks.
4959 if (!is_complete_with_arraycopy()) {
4960 // We are going to look at each use of the memory state following
4961 // the allocation to make sure nothing reads the memory that the
4962 // Store writes.
4963 const TypePtr* t_adr = phase->type(adr)->isa_ptr();
4964 int alias_idx = phase->C->get_alias_index(t_adr);
4965 ResourceMark rm;
4966 Unique_Node_List mems;
4967 mems.push(mem);
4968 Node* unique_merge = nullptr;
4969 for (uint next = 0; next < mems.size(); ++next) {
4970 Node *m = mems.at(next);
4971 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
4972 Node *n = m->fast_out(j);
4973 if (n->outcnt() == 0) {
4974 continue;
4975 }
4976 if (n == st) {
4977 continue;
4978 } else if (n->in(0) != nullptr && n->in(0) != ctl) {
4979 // If the control of this use is different from the control
4980 // of the Store which is right after the InitializeNode then
4981 // this node cannot be between the InitializeNode and the
4982 // Store.
4983 continue;
4984 } else if (n->is_MergeMem()) {
4985 if (n->as_MergeMem()->memory_at(alias_idx) == m) {
4986 // We can hit a MergeMemNode (that will likely go away
4987 // later) that is a direct use of the memory state
4988 // following the InitializeNode on the same slice as the
4989 // store node that we'd like to capture. We need to check
4990 // the uses of the MergeMemNode.
4991 mems.push(n);
4992 }
4993 } else if (n->is_Mem()) {
4994 Node* other_adr = n->in(MemNode::Address);
4995 if (other_adr == adr) {
4996 failed = true;
4997 break;
4998 } else {
4999 const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr();
5000 if (other_t_adr != nullptr) {
5001 int other_alias_idx = phase->C->get_alias_index(other_t_adr);
5002 if (other_alias_idx == alias_idx) {
5003 // A load from the same memory slice as the store right
5004 // after the InitializeNode. We check the control of the
5005 // object/array that is loaded from. If it's the same as
5006 // the store control then we cannot capture the store.
5007 assert(!n->is_Store(), "2 stores to same slice on same control?");
5008 Node* base = other_adr;
5009 if (base->is_Phi()) {
5010 // In rare case, base may be a PhiNode and it may read
5011 // the same memory slice between InitializeNode and store.
5012 failed = true;
5013 break;
5014 }
5015 assert(base->is_AddP(), "should be addp but is %s", base->Name());
5016 base = base->in(AddPNode::Base);
5017 if (base != nullptr) {
5018 base = base->uncast();
5019 if (base->is_Proj() && base->in(0) == alloc) {
5020 failed = true;
5021 break;
5022 }
5023 }
5024 }
5025 }
5026 }
5027 } else {
5028 failed = true;
5029 break;
5030 }
5031 }
5032 }
5033 }
5034 if (failed) {
5035 if (!can_reshape) {
5036 // We decided we couldn't capture the store during parsing. We
5037 // should try again during the next IGVN once the graph is
5038 // cleaner.
5039 phase->C->record_for_igvn(st);
5040 }
5041 return FAIL;
5042 }
5043
5044 return offset; // success
5045 }
5046
5047 // Find the captured store in(i) which corresponds to the range
5048 // [start..start+size) in the initialized object.
5049 // If there is one, return its index i. If there isn't, return the
5050 // negative of the index where it should be inserted.
5051 // Return 0 if the queried range overlaps an initialization boundary
5052 // or if dead code is encountered.
5053 // If size_in_bytes is zero, do not bother with overlap checks.
5054 int InitializeNode::captured_store_insertion_point(intptr_t start,
5055 int size_in_bytes,
5056 PhaseValues* phase) {
5057 const int FAIL = 0, MAX_STORE = MAX2(BytesPerLong, (int)MaxVectorSize);
5058
5059 if (is_complete())
5060 return FAIL; // arraycopy got here first; punt
5061
5062 assert(allocation() != nullptr, "must be present");
5063
5064 // no negatives, no header fields:
5065 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
5066
5067 // after a certain size, we bail out on tracking all the stores:
5068 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
5069 if (start >= ti_limit) return FAIL;
5070
5071 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
5072 if (i >= limit) return -(int)i; // not found; here is where to put it
5073
5074 Node* st = in(i);
5075 intptr_t st_off = get_store_offset(st, phase);
5076 if (st_off < 0) {
5077 if (st != zero_memory()) {
5078 return FAIL; // bail out if there is dead garbage
5079 }
5080 } else if (st_off > start) {
5081 // ...we are done, since stores are ordered
5082 if (st_off < start + size_in_bytes) {
5083 return FAIL; // the next store overlaps
5084 }
5085 return -(int)i; // not found; here is where to put it
5086 } else if (st_off < start) {
5087 assert(st->as_Store()->memory_size() <= MAX_STORE, "");
5088 if (size_in_bytes != 0 &&
5089 start < st_off + MAX_STORE &&
5090 start < st_off + st->as_Store()->memory_size()) {
5091 return FAIL; // the previous store overlaps
5092 }
5093 } else {
5094 if (size_in_bytes != 0 &&
5095 st->as_Store()->memory_size() != size_in_bytes) {
5096 return FAIL; // mismatched store size
5097 }
5098 return i;
5099 }
5100
5101 ++i;
5102 }
5103 }
5104
5105 // Look for a captured store which initializes at the offset 'start'
5106 // with the given size. If there is no such store, and no other
5107 // initialization interferes, then return zero_memory (the memory
5108 // projection of the AllocateNode).
5109 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
5110 PhaseValues* phase) {
5111 assert(stores_are_sane(phase), "");
5112 int i = captured_store_insertion_point(start, size_in_bytes, phase);
5113 if (i == 0) {
5114 return nullptr; // something is dead
5115 } else if (i < 0) {
5116 return zero_memory(); // just primordial zero bits here
5117 } else {
5118 Node* st = in(i); // here is the store at this position
5119 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
5120 return st;
5121 }
5122 }
5123
5124 // Create, as a raw pointer, an address within my new object at 'offset'.
5125 Node* InitializeNode::make_raw_address(intptr_t offset,
5126 PhaseGVN* phase) {
5127 Node* addr = in(RawAddress);
5128 if (offset != 0) {
5129 Compile* C = phase->C;
5130 addr = phase->transform( new AddPNode(C->top(), addr,
5131 phase->MakeConX(offset)) );
5132 }
5133 return addr;
5134 }
5135
5136 // Clone the given store, converting it into a raw store
5137 // initializing a field or element of my new object.
5138 // Caller is responsible for retiring the original store,
5139 // with subsume_node or the like.
5140 //
5141 // From the example above InitializeNode::InitializeNode,
5142 // here are the old stores to be captured:
5143 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
5144 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
5145 //
5146 // Here is the changed code; note the extra edges on init:
5147 // alloc = (Allocate ...)
5148 // rawoop = alloc.RawAddress
5149 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
5150 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
5151 // init = (Initialize alloc.Control alloc.Memory rawoop
5152 // rawstore1 rawstore2)
5153 //
5154 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
5155 PhaseGVN* phase, bool can_reshape) {
5156 assert(stores_are_sane(phase), "");
5157
5158 if (start < 0) return nullptr;
5159 assert(can_capture_store(st, phase, can_reshape) == start, "sanity");
5160
5161 Compile* C = phase->C;
5162 int size_in_bytes = st->memory_size();
5163 int i = captured_store_insertion_point(start, size_in_bytes, phase);
5164 if (i == 0) return nullptr; // bail out
5165 Node* prev_mem = nullptr; // raw memory for the captured store
5166 if (i > 0) {
5167 prev_mem = in(i); // there is a pre-existing store under this one
5168 set_req(i, C->top()); // temporarily disconnect it
5169 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
5170 } else {
5171 i = -i; // no pre-existing store
5172 prev_mem = zero_memory(); // a slice of the newly allocated object
5173 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
5174 set_req(--i, C->top()); // reuse this edge; it has been folded away
5175 else
5176 ins_req(i, C->top()); // build a new edge
5177 }
5178 Node* new_st = st->clone();
5179 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
5180 new_st->set_req(MemNode::Control, in(Control));
5181 new_st->set_req(MemNode::Memory, prev_mem);
5182 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
5183 bs->eliminate_gc_barrier_data(new_st);
5184 new_st = phase->transform(new_st);
5185
5186 // At this point, new_st might have swallowed a pre-existing store
5187 // at the same offset, or perhaps new_st might have disappeared,
5188 // if it redundantly stored the same value (or zero to fresh memory).
5189
5190 // In any case, wire it in:
5191 PhaseIterGVN* igvn = phase->is_IterGVN();
5192 if (igvn) {
5193 igvn->rehash_node_delayed(this);
5194 }
5195 set_req(i, new_st);
5196
5197 // The caller may now kill the old guy.
5198 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
5199 assert(check_st == new_st || check_st == nullptr, "must be findable");
5200 assert(!is_complete(), "");
5201 return new_st;
5202 }
5203
5204 static bool store_constant(jlong* tiles, int num_tiles,
5205 intptr_t st_off, int st_size,
5206 jlong con) {
5207 if ((st_off & (st_size-1)) != 0)
5208 return false; // strange store offset (assume size==2**N)
5209 address addr = (address)tiles + st_off;
5210 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
5211 switch (st_size) {
5212 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
5213 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
5214 case sizeof(jint): *(jint*) addr = (jint) con; break;
5215 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
5216 default: return false; // strange store size (detect size!=2**N here)
5217 }
5218 return true; // return success to caller
5219 }
5220
5221 // Coalesce subword constants into int constants and possibly
5222 // into long constants. The goal, if the CPU permits,
5223 // is to initialize the object with a small number of 64-bit tiles.
5224 // Also, convert floating-point constants to bit patterns.
5225 // Non-constants are not relevant to this pass.
5226 //
5227 // In terms of the running example on InitializeNode::InitializeNode
5228 // and InitializeNode::capture_store, here is the transformation
5229 // of rawstore1 and rawstore2 into rawstore12:
5230 // alloc = (Allocate ...)
5231 // rawoop = alloc.RawAddress
5232 // tile12 = 0x00010002
5233 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
5234 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
5235 //
5236 void
5237 InitializeNode::coalesce_subword_stores(intptr_t header_size,
5238 Node* size_in_bytes,
5239 PhaseGVN* phase) {
5240 Compile* C = phase->C;
5241
5242 assert(stores_are_sane(phase), "");
5243 // Note: After this pass, they are not completely sane,
5244 // since there may be some overlaps.
5245
5246 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
5247
5248 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
5249 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
5250 size_limit = MIN2(size_limit, ti_limit);
5251 size_limit = align_up(size_limit, BytesPerLong);
5252 int num_tiles = size_limit / BytesPerLong;
5253
5254 // allocate space for the tile map:
5255 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
5256 jlong tiles_buf[small_len];
5257 Node* nodes_buf[small_len];
5258 jlong inits_buf[small_len];
5259 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
5260 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
5261 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
5262 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
5263 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
5264 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
5265 // tiles: exact bitwise model of all primitive constants
5266 // nodes: last constant-storing node subsumed into the tiles model
5267 // inits: which bytes (in each tile) are touched by any initializations
5268
5269 //// Pass A: Fill in the tile model with any relevant stores.
5270
5271 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
5272 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
5273 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
5274 Node* zmem = zero_memory(); // initially zero memory state
5275 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
5276 Node* st = in(i);
5277 intptr_t st_off = get_store_offset(st, phase);
5278
5279 // Figure out the store's offset and constant value:
5280 if (st_off < header_size) continue; //skip (ignore header)
5281 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
5282 int st_size = st->as_Store()->memory_size();
5283 if (st_off + st_size > size_limit) break;
5284
5285 // Record which bytes are touched, whether by constant or not.
5286 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
5287 continue; // skip (strange store size)
5288
5289 const Type* val = phase->type(st->in(MemNode::ValueIn));
5290 if (!val->singleton()) continue; //skip (non-con store)
5291 BasicType type = val->basic_type();
5292
5293 jlong con = 0;
5294 switch (type) {
5295 case T_INT: con = val->is_int()->get_con(); break;
5296 case T_LONG: con = val->is_long()->get_con(); break;
5297 case T_FLOAT: con = jint_cast(val->getf()); break;
5298 case T_DOUBLE: con = jlong_cast(val->getd()); break;
5299 default: continue; //skip (odd store type)
5300 }
5301
5302 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
5303 st->Opcode() == Op_StoreL) {
5304 continue; // This StoreL is already optimal.
5305 }
5306
5307 // Store down the constant.
5308 store_constant(tiles, num_tiles, st_off, st_size, con);
5309
5310 intptr_t j = st_off >> LogBytesPerLong;
5311
5312 if (type == T_INT && st_size == BytesPerInt
5313 && (st_off & BytesPerInt) == BytesPerInt) {
5314 jlong lcon = tiles[j];
5315 if (!Matcher::isSimpleConstant64(lcon) &&
5316 st->Opcode() == Op_StoreI) {
5317 // This StoreI is already optimal by itself.
5318 jint* intcon = (jint*) &tiles[j];
5319 intcon[1] = 0; // undo the store_constant()
5320
5321 // If the previous store is also optimal by itself, back up and
5322 // undo the action of the previous loop iteration... if we can.
5323 // But if we can't, just let the previous half take care of itself.
5324 st = nodes[j];
5325 st_off -= BytesPerInt;
5326 con = intcon[0];
5327 if (con != 0 && st != nullptr && st->Opcode() == Op_StoreI) {
5328 assert(st_off >= header_size, "still ignoring header");
5329 assert(get_store_offset(st, phase) == st_off, "must be");
5330 assert(in(i-1) == zmem, "must be");
5331 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
5332 assert(con == tcon->is_int()->get_con(), "must be");
5333 // Undo the effects of the previous loop trip, which swallowed st:
5334 intcon[0] = 0; // undo store_constant()
5335 set_req(i-1, st); // undo set_req(i, zmem)
5336 nodes[j] = nullptr; // undo nodes[j] = st
5337 --old_subword; // undo ++old_subword
5338 }
5339 continue; // This StoreI is already optimal.
5340 }
5341 }
5342
5343 // This store is not needed.
5344 set_req(i, zmem);
5345 nodes[j] = st; // record for the moment
5346 if (st_size < BytesPerLong) // something has changed
5347 ++old_subword; // includes int/float, but who's counting...
5348 else ++old_long;
5349 }
5350
5351 if ((old_subword + old_long) == 0)
5352 return; // nothing more to do
5353
5354 //// Pass B: Convert any non-zero tiles into optimal constant stores.
5355 // Be sure to insert them before overlapping non-constant stores.
5356 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
5357 for (int j = 0; j < num_tiles; j++) {
5358 jlong con = tiles[j];
5359 jlong init = inits[j];
5360 if (con == 0) continue;
5361 jint con0, con1; // split the constant, address-wise
5362 jint init0, init1; // split the init map, address-wise
5363 { union { jlong con; jint intcon[2]; } u;
5364 u.con = con;
5365 con0 = u.intcon[0];
5366 con1 = u.intcon[1];
5367 u.con = init;
5368 init0 = u.intcon[0];
5369 init1 = u.intcon[1];
5370 }
5371
5372 Node* old = nodes[j];
5373 assert(old != nullptr, "need the prior store");
5374 intptr_t offset = (j * BytesPerLong);
5375
5376 bool split = !Matcher::isSimpleConstant64(con);
5377
5378 if (offset < header_size) {
5379 assert(offset + BytesPerInt >= header_size, "second int counts");
5380 assert(*(jint*)&tiles[j] == 0, "junk in header");
5381 split = true; // only the second word counts
5382 // Example: int a[] = { 42 ... }
5383 } else if (con0 == 0 && init0 == -1) {
5384 split = true; // first word is covered by full inits
5385 // Example: int a[] = { ... foo(), 42 ... }
5386 } else if (con1 == 0 && init1 == -1) {
5387 split = true; // second word is covered by full inits
5388 // Example: int a[] = { ... 42, foo() ... }
5389 }
5390
5391 // Here's a case where init0 is neither 0 nor -1:
5392 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
5393 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
5394 // In this case the tile is not split; it is (jlong)42.
5395 // The big tile is stored down, and then the foo() value is inserted.
5396 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
5397
5398 Node* ctl = old->in(MemNode::Control);
5399 Node* adr = make_raw_address(offset, phase);
5400 const TypePtr* atp = TypeRawPtr::BOTTOM;
5401
5402 // One or two coalesced stores to plop down.
5403 Node* st[2];
5404 intptr_t off[2];
5405 int nst = 0;
5406 if (!split) {
5407 ++new_long;
5408 off[nst] = offset;
5409 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
5410 phase->longcon(con), T_LONG, MemNode::unordered);
5411 } else {
5412 // Omit either if it is a zero.
5413 if (con0 != 0) {
5414 ++new_int;
5415 off[nst] = offset;
5416 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
5417 phase->intcon(con0), T_INT, MemNode::unordered);
5418 }
5419 if (con1 != 0) {
5420 ++new_int;
5421 offset += BytesPerInt;
5422 adr = make_raw_address(offset, phase);
5423 off[nst] = offset;
5424 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
5425 phase->intcon(con1), T_INT, MemNode::unordered);
5426 }
5427 }
5428
5429 // Insert second store first, then the first before the second.
5430 // Insert each one just before any overlapping non-constant stores.
5431 while (nst > 0) {
5432 Node* st1 = st[--nst];
5433 C->copy_node_notes_to(st1, old);
5434 st1 = phase->transform(st1);
5435 offset = off[nst];
5436 assert(offset >= header_size, "do not smash header");
5437 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
5438 guarantee(ins_idx != 0, "must re-insert constant store");
5439 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
5440 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
5441 set_req(--ins_idx, st1);
5442 else
5443 ins_req(ins_idx, st1);
5444 }
5445 }
5446
5447 if (PrintCompilation && WizardMode)
5448 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
5449 old_subword, old_long, new_int, new_long);
5450 if (C->log() != nullptr)
5451 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
5452 old_subword, old_long, new_int, new_long);
5453
5454 // Clean up any remaining occurrences of zmem:
5455 remove_extra_zeroes();
5456 }
5457
5458 // Explore forward from in(start) to find the first fully initialized
5459 // word, and return its offset. Skip groups of subword stores which
5460 // together initialize full words. If in(start) is itself part of a
5461 // fully initialized word, return the offset of in(start). If there
5462 // are no following full-word stores, or if something is fishy, return
5463 // a negative value.
5464 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
5465 int int_map = 0;
5466 intptr_t int_map_off = 0;
5467 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
5468
5469 for (uint i = start, limit = req(); i < limit; i++) {
5470 Node* st = in(i);
5471
5472 intptr_t st_off = get_store_offset(st, phase);
5473 if (st_off < 0) break; // return conservative answer
5474
5475 int st_size = st->as_Store()->memory_size();
5476 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
5477 return st_off; // we found a complete word init
5478 }
5479
5480 // update the map:
5481
5482 intptr_t this_int_off = align_down(st_off, BytesPerInt);
5483 if (this_int_off != int_map_off) {
5484 // reset the map:
5485 int_map = 0;
5486 int_map_off = this_int_off;
5487 }
5488
5489 int subword_off = st_off - this_int_off;
5490 int_map |= right_n_bits(st_size) << subword_off;
5491 if ((int_map & FULL_MAP) == FULL_MAP) {
5492 return this_int_off; // we found a complete word init
5493 }
5494
5495 // Did this store hit or cross the word boundary?
5496 intptr_t next_int_off = align_down(st_off + st_size, BytesPerInt);
5497 if (next_int_off == this_int_off + BytesPerInt) {
5498 // We passed the current int, without fully initializing it.
5499 int_map_off = next_int_off;
5500 int_map >>= BytesPerInt;
5501 } else if (next_int_off > this_int_off + BytesPerInt) {
5502 // We passed the current and next int.
5503 return this_int_off + BytesPerInt;
5504 }
5505 }
5506
5507 return -1;
5508 }
5509
5510
5511 // Called when the associated AllocateNode is expanded into CFG.
5512 // At this point, we may perform additional optimizations.
5513 // Linearize the stores by ascending offset, to make memory
5514 // activity as coherent as possible.
5515 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
5516 intptr_t header_size,
5517 Node* size_in_bytes,
5518 PhaseIterGVN* phase) {
5519 assert(!is_complete(), "not already complete");
5520 assert(stores_are_sane(phase), "");
5521 assert(allocation() != nullptr, "must be present");
5522
5523 remove_extra_zeroes();
5524
5525 if (ReduceFieldZeroing || ReduceBulkZeroing)
5526 // reduce instruction count for common initialization patterns
5527 coalesce_subword_stores(header_size, size_in_bytes, phase);
5528
5529 Node* zmem = zero_memory(); // initially zero memory state
5530 Node* inits = zmem; // accumulating a linearized chain of inits
5531 #ifdef ASSERT
5532 intptr_t first_offset = allocation()->minimum_header_size();
5533 intptr_t last_init_off = first_offset; // previous init offset
5534 intptr_t last_init_end = first_offset; // previous init offset+size
5535 intptr_t last_tile_end = first_offset; // previous tile offset+size
5536 #endif
5537 intptr_t zeroes_done = header_size;
5538
5539 bool do_zeroing = true; // we might give up if inits are very sparse
5540 int big_init_gaps = 0; // how many large gaps have we seen?
5541
5542 if (UseTLAB && ZeroTLAB) do_zeroing = false;
5543 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
5544
5545 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
5546 Node* st = in(i);
5547 intptr_t st_off = get_store_offset(st, phase);
5548 if (st_off < 0)
5549 break; // unknown junk in the inits
5550 if (st->in(MemNode::Memory) != zmem)
5551 break; // complicated store chains somehow in list
5552
5553 int st_size = st->as_Store()->memory_size();
5554 intptr_t next_init_off = st_off + st_size;
5555
5556 if (do_zeroing && zeroes_done < next_init_off) {
5557 // See if this store needs a zero before it or under it.
5558 intptr_t zeroes_needed = st_off;
5559
5560 if (st_size < BytesPerInt) {
5561 // Look for subword stores which only partially initialize words.
5562 // If we find some, we must lay down some word-level zeroes first,
5563 // underneath the subword stores.
5564 //
5565 // Examples:
5566 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
5567 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
5568 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
5569 //
5570 // Note: coalesce_subword_stores may have already done this,
5571 // if it was prompted by constant non-zero subword initializers.
5572 // But this case can still arise with non-constant stores.
5573
5574 intptr_t next_full_store = find_next_fullword_store(i, phase);
5575
5576 // In the examples above:
5577 // in(i) p q r s x y z
5578 // st_off 12 13 14 15 12 13 14
5579 // st_size 1 1 1 1 1 1 1
5580 // next_full_s. 12 16 16 16 16 16 16
5581 // z's_done 12 16 16 16 12 16 12
5582 // z's_needed 12 16 16 16 16 16 16
5583 // zsize 0 0 0 0 4 0 4
5584 if (next_full_store < 0) {
5585 // Conservative tack: Zero to end of current word.
5586 zeroes_needed = align_up(zeroes_needed, BytesPerInt);
5587 } else {
5588 // Zero to beginning of next fully initialized word.
5589 // Or, don't zero at all, if we are already in that word.
5590 assert(next_full_store >= zeroes_needed, "must go forward");
5591 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
5592 zeroes_needed = next_full_store;
5593 }
5594 }
5595
5596 if (zeroes_needed > zeroes_done) {
5597 intptr_t zsize = zeroes_needed - zeroes_done;
5598 // Do some incremental zeroing on rawmem, in parallel with inits.
5599 zeroes_done = align_down(zeroes_done, BytesPerInt);
5600 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
5601 allocation()->in(AllocateNode::InitValue),
5602 allocation()->in(AllocateNode::RawInitValue),
5603 zeroes_done, zeroes_needed,
5604 phase);
5605 zeroes_done = zeroes_needed;
5606 if (zsize > InitArrayShortSize && ++big_init_gaps > 2)
5607 do_zeroing = false; // leave the hole, next time
5608 }
5609 }
5610
5611 // Collect the store and move on:
5612 phase->replace_input_of(st, MemNode::Memory, inits);
5613 inits = st; // put it on the linearized chain
5614 set_req(i, zmem); // unhook from previous position
5615
5616 if (zeroes_done == st_off)
5617 zeroes_done = next_init_off;
5618
5619 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
5620
5621 #ifdef ASSERT
5622 // Various order invariants. Weaker than stores_are_sane because
5623 // a large constant tile can be filled in by smaller non-constant stores.
5624 assert(st_off >= last_init_off, "inits do not reverse");
5625 last_init_off = st_off;
5626 const Type* val = nullptr;
5627 if (st_size >= BytesPerInt &&
5628 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
5629 (int)val->basic_type() < (int)T_OBJECT) {
5630 assert(st_off >= last_tile_end, "tiles do not overlap");
5631 assert(st_off >= last_init_end, "tiles do not overwrite inits");
5632 last_tile_end = MAX2(last_tile_end, next_init_off);
5633 } else {
5634 intptr_t st_tile_end = align_up(next_init_off, BytesPerLong);
5635 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
5636 assert(st_off >= last_init_end, "inits do not overlap");
5637 last_init_end = next_init_off; // it's a non-tile
5638 }
5639 #endif //ASSERT
5640 }
5641
5642 remove_extra_zeroes(); // clear out all the zmems left over
5643 add_req(inits);
5644
5645 if (!(UseTLAB && ZeroTLAB)) {
5646 // If anything remains to be zeroed, zero it all now.
5647 zeroes_done = align_down(zeroes_done, BytesPerInt);
5648 // if it is the last unused 4 bytes of an instance, forget about it
5649 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
5650 if (zeroes_done + BytesPerLong >= size_limit) {
5651 AllocateNode* alloc = allocation();
5652 assert(alloc != nullptr, "must be present");
5653 if (alloc != nullptr && alloc->Opcode() == Op_Allocate) {
5654 Node* klass_node = alloc->in(AllocateNode::KlassNode);
5655 ciKlass* k = phase->type(klass_node)->is_instklassptr()->instance_klass();
5656 if (zeroes_done == k->layout_helper())
5657 zeroes_done = size_limit;
5658 }
5659 }
5660 if (zeroes_done < size_limit) {
5661 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
5662 allocation()->in(AllocateNode::InitValue),
5663 allocation()->in(AllocateNode::RawInitValue),
5664 zeroes_done, size_in_bytes, phase);
5665 }
5666 }
5667
5668 set_complete(phase);
5669 return rawmem;
5670 }
5671
5672
5673 #ifdef ASSERT
5674 bool InitializeNode::stores_are_sane(PhaseValues* phase) {
5675 if (is_complete())
5676 return true; // stores could be anything at this point
5677 assert(allocation() != nullptr, "must be present");
5678 intptr_t last_off = allocation()->minimum_header_size();
5679 for (uint i = InitializeNode::RawStores; i < req(); i++) {
5680 Node* st = in(i);
5681 intptr_t st_off = get_store_offset(st, phase);
5682 if (st_off < 0) continue; // ignore dead garbage
5683 if (last_off > st_off) {
5684 tty->print_cr("*** bad store offset at %d: %zd > %zd", i, last_off, st_off);
5685 this->dump(2);
5686 assert(false, "ascending store offsets");
5687 return false;
5688 }
5689 last_off = st_off + st->as_Store()->memory_size();
5690 }
5691 return true;
5692 }
5693 #endif //ASSERT
5694
5695
5696
5697
5698 //============================MergeMemNode=====================================
5699 //
5700 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
5701 // contributing store or call operations. Each contributor provides the memory
5702 // state for a particular "alias type" (see Compile::alias_type). For example,
5703 // if a MergeMem has an input X for alias category #6, then any memory reference
5704 // to alias category #6 may use X as its memory state input, as an exact equivalent
5705 // to using the MergeMem as a whole.
5706 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
5707 //
5708 // (Here, the <N> notation gives the index of the relevant adr_type.)
5709 //
5710 // In one special case (and more cases in the future), alias categories overlap.
5711 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
5712 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
5713 // it is exactly equivalent to that state W:
5714 // MergeMem(<Bot>: W) <==> W
5715 //
5716 // Usually, the merge has more than one input. In that case, where inputs
5717 // overlap (i.e., one is Bot), the narrower alias type determines the memory
5718 // state for that type, and the wider alias type (Bot) fills in everywhere else:
5719 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
5720 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
5721 //
5722 // A merge can take a "wide" memory state as one of its narrow inputs.
5723 // This simply means that the merge observes out only the relevant parts of
5724 // the wide input. That is, wide memory states arriving at narrow merge inputs
5725 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
5726 //
5727 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
5728 // and that memory slices "leak through":
5729 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
5730 //
5731 // But, in such a cascade, repeated memory slices can "block the leak":
5732 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
5733 //
5734 // In the last example, Y is not part of the combined memory state of the
5735 // outermost MergeMem. The system must, of course, prevent unschedulable
5736 // memory states from arising, so you can be sure that the state Y is somehow
5737 // a precursor to state Y'.
5738 //
5739 //
5740 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
5741 // of each MergeMemNode array are exactly the numerical alias indexes, including
5742 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
5743 // Compile::alias_type (and kin) produce and manage these indexes.
5744 //
5745 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
5746 // (Note that this provides quick access to the top node inside MergeMem methods,
5747 // without the need to reach out via TLS to Compile::current.)
5748 //
5749 // As a consequence of what was just described, a MergeMem that represents a full
5750 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
5751 // containing all alias categories.
5752 //
5753 // MergeMem nodes never (?) have control inputs, so in(0) is null.
5754 //
5755 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
5756 // a memory state for the alias type <N>, or else the top node, meaning that
5757 // there is no particular input for that alias type. Note that the length of
5758 // a MergeMem is variable, and may be extended at any time to accommodate new
5759 // memory states at larger alias indexes. When merges grow, they are of course
5760 // filled with "top" in the unused in() positions.
5761 //
5762 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
5763 // (Top was chosen because it works smoothly with passes like GCM.)
5764 //
5765 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
5766 // the type of random VM bits like TLS references.) Since it is always the
5767 // first non-Bot memory slice, some low-level loops use it to initialize an
5768 // index variable: for (i = AliasIdxRaw; i < req(); i++).
5769 //
5770 //
5771 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
5772 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
5773 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
5774 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
5775 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
5776 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
5777 //
5778 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
5779 // really that different from the other memory inputs. An abbreviation called
5780 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
5781 //
5782 //
5783 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
5784 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
5785 // that "emerges though" the base memory will be marked as excluding the alias types
5786 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
5787 //
5788 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
5789 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
5790 //
5791 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
5792 // (It is currently unimplemented.) As you can see, the resulting merge is
5793 // actually a disjoint union of memory states, rather than an overlay.
5794 //
5795
5796 //------------------------------MergeMemNode-----------------------------------
5797 Node* MergeMemNode::make_empty_memory() {
5798 Node* empty_memory = (Node*) Compile::current()->top();
5799 assert(empty_memory->is_top(), "correct sentinel identity");
5800 return empty_memory;
5801 }
5802
5803 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
5804 init_class_id(Class_MergeMem);
5805 // all inputs are nullified in Node::Node(int)
5806 // set_input(0, nullptr); // no control input
5807
5808 // Initialize the edges uniformly to top, for starters.
5809 Node* empty_mem = make_empty_memory();
5810 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
5811 init_req(i,empty_mem);
5812 }
5813 assert(empty_memory() == empty_mem, "");
5814
5815 if( new_base != nullptr && new_base->is_MergeMem() ) {
5816 MergeMemNode* mdef = new_base->as_MergeMem();
5817 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
5818 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
5819 mms.set_memory(mms.memory2());
5820 }
5821 assert(base_memory() == mdef->base_memory(), "");
5822 } else {
5823 set_base_memory(new_base);
5824 }
5825 }
5826
5827 // Make a new, untransformed MergeMem with the same base as 'mem'.
5828 // If mem is itself a MergeMem, populate the result with the same edges.
5829 MergeMemNode* MergeMemNode::make(Node* mem) {
5830 return new MergeMemNode(mem);
5831 }
5832
5833 //------------------------------cmp--------------------------------------------
5834 uint MergeMemNode::hash() const { return NO_HASH; }
5835 bool MergeMemNode::cmp( const Node &n ) const {
5836 return (&n == this); // Always fail except on self
5837 }
5838
5839 //------------------------------Identity---------------------------------------
5840 Node* MergeMemNode::Identity(PhaseGVN* phase) {
5841 // Identity if this merge point does not record any interesting memory
5842 // disambiguations.
5843 Node* base_mem = base_memory();
5844 Node* empty_mem = empty_memory();
5845 if (base_mem != empty_mem) { // Memory path is not dead?
5846 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5847 Node* mem = in(i);
5848 if (mem != empty_mem && mem != base_mem) {
5849 return this; // Many memory splits; no change
5850 }
5851 }
5852 }
5853 return base_mem; // No memory splits; ID on the one true input
5854 }
5855
5856 //------------------------------Ideal------------------------------------------
5857 // This method is invoked recursively on chains of MergeMem nodes
5858 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
5859 // Remove chain'd MergeMems
5860 //
5861 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
5862 // relative to the "in(Bot)". Since we are patching both at the same time,
5863 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
5864 // but rewrite each "in(i)" relative to the new "in(Bot)".
5865 Node *progress = nullptr;
5866
5867
5868 Node* old_base = base_memory();
5869 Node* empty_mem = empty_memory();
5870 if (old_base == empty_mem)
5871 return nullptr; // Dead memory path.
5872
5873 MergeMemNode* old_mbase;
5874 if (old_base != nullptr && old_base->is_MergeMem())
5875 old_mbase = old_base->as_MergeMem();
5876 else
5877 old_mbase = nullptr;
5878 Node* new_base = old_base;
5879
5880 // simplify stacked MergeMems in base memory
5881 if (old_mbase) new_base = old_mbase->base_memory();
5882
5883 // the base memory might contribute new slices beyond my req()
5884 if (old_mbase) grow_to_match(old_mbase);
5885
5886 // Note: We do not call verify_sparse on entry, because inputs
5887 // can normalize to the base_memory via subsume_node or similar
5888 // mechanisms. This method repairs that damage.
5889
5890 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
5891
5892 // Look at each slice.
5893 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5894 Node* old_in = in(i);
5895 // calculate the old memory value
5896 Node* old_mem = old_in;
5897 if (old_mem == empty_mem) old_mem = old_base;
5898 assert(old_mem == memory_at(i), "");
5899
5900 // maybe update (reslice) the old memory value
5901
5902 // simplify stacked MergeMems
5903 Node* new_mem = old_mem;
5904 MergeMemNode* old_mmem;
5905 if (old_mem != nullptr && old_mem->is_MergeMem())
5906 old_mmem = old_mem->as_MergeMem();
5907 else
5908 old_mmem = nullptr;
5909 if (old_mmem == this) {
5910 // This can happen if loops break up and safepoints disappear.
5911 // A merge of BotPtr (default) with a RawPtr memory derived from a
5912 // safepoint can be rewritten to a merge of the same BotPtr with
5913 // the BotPtr phi coming into the loop. If that phi disappears
5914 // also, we can end up with a self-loop of the mergemem.
5915 // In general, if loops degenerate and memory effects disappear,
5916 // a mergemem can be left looking at itself. This simply means
5917 // that the mergemem's default should be used, since there is
5918 // no longer any apparent effect on this slice.
5919 // Note: If a memory slice is a MergeMem cycle, it is unreachable
5920 // from start. Update the input to TOP.
5921 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
5922 }
5923 else if (old_mmem != nullptr) {
5924 new_mem = old_mmem->memory_at(i);
5925 }
5926 // else preceding memory was not a MergeMem
5927
5928 // maybe store down a new value
5929 Node* new_in = new_mem;
5930 if (new_in == new_base) new_in = empty_mem;
5931
5932 if (new_in != old_in) {
5933 // Warning: Do not combine this "if" with the previous "if"
5934 // A memory slice might have be be rewritten even if it is semantically
5935 // unchanged, if the base_memory value has changed.
5936 set_req_X(i, new_in, phase);
5937 progress = this; // Report progress
5938 }
5939 }
5940
5941 if (new_base != old_base) {
5942 set_req_X(Compile::AliasIdxBot, new_base, phase);
5943 // Don't use set_base_memory(new_base), because we need to update du.
5944 assert(base_memory() == new_base, "");
5945 progress = this;
5946 }
5947
5948 if( base_memory() == this ) {
5949 // a self cycle indicates this memory path is dead
5950 set_req(Compile::AliasIdxBot, empty_mem);
5951 }
5952
5953 // Resolve external cycles by calling Ideal on a MergeMem base_memory
5954 // Recursion must occur after the self cycle check above
5955 if( base_memory()->is_MergeMem() ) {
5956 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
5957 Node *m = phase->transform(new_mbase); // Rollup any cycles
5958 if( m != nullptr &&
5959 (m->is_top() ||
5960 (m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem)) ) {
5961 // propagate rollup of dead cycle to self
5962 set_req(Compile::AliasIdxBot, empty_mem);
5963 }
5964 }
5965
5966 if( base_memory() == empty_mem ) {
5967 progress = this;
5968 // Cut inputs during Parse phase only.
5969 // During Optimize phase a dead MergeMem node will be subsumed by Top.
5970 if( !can_reshape ) {
5971 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5972 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
5973 }
5974 }
5975 }
5976
5977 if( !progress && base_memory()->is_Phi() && can_reshape ) {
5978 // Check if PhiNode::Ideal's "Split phis through memory merges"
5979 // transform should be attempted. Look for this->phi->this cycle.
5980 uint merge_width = req();
5981 if (merge_width > Compile::AliasIdxRaw) {
5982 PhiNode* phi = base_memory()->as_Phi();
5983 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
5984 if (phi->in(i) == this) {
5985 phase->is_IterGVN()->_worklist.push(phi);
5986 break;
5987 }
5988 }
5989 }
5990 }
5991
5992 assert(progress || verify_sparse(), "please, no dups of base");
5993 return progress;
5994 }
5995
5996 //-------------------------set_base_memory-------------------------------------
5997 void MergeMemNode::set_base_memory(Node *new_base) {
5998 Node* empty_mem = empty_memory();
5999 set_req(Compile::AliasIdxBot, new_base);
6000 assert(memory_at(req()) == new_base, "must set default memory");
6001 // Clear out other occurrences of new_base:
6002 if (new_base != empty_mem) {
6003 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
6004 if (in(i) == new_base) set_req(i, empty_mem);
6005 }
6006 }
6007 }
6008
6009 //------------------------------out_RegMask------------------------------------
6010 const RegMask &MergeMemNode::out_RegMask() const {
6011 return RegMask::Empty;
6012 }
6013
6014 //------------------------------dump_spec--------------------------------------
6015 #ifndef PRODUCT
6016 void MergeMemNode::dump_spec(outputStream *st) const {
6017 st->print(" {");
6018 Node* base_mem = base_memory();
6019 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
6020 Node* mem = (in(i) != nullptr) ? memory_at(i) : base_mem;
6021 if (mem == base_mem) { st->print(" -"); continue; }
6022 st->print( " N%d:", mem->_idx );
6023 Compile::current()->get_adr_type(i)->dump_on(st);
6024 }
6025 st->print(" }");
6026 }
6027 #endif // !PRODUCT
6028
6029
6030 #ifdef ASSERT
6031 static bool might_be_same(Node* a, Node* b) {
6032 if (a == b) return true;
6033 if (!(a->is_Phi() || b->is_Phi())) return false;
6034 // phis shift around during optimization
6035 return true; // pretty stupid...
6036 }
6037
6038 // verify a narrow slice (either incoming or outgoing)
6039 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
6040 if (!VerifyAliases) return; // don't bother to verify unless requested
6041 if (VMError::is_error_reported()) return; // muzzle asserts when debugging an error
6042 if (Node::in_dump()) return; // muzzle asserts when printing
6043 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
6044 assert(n != nullptr, "");
6045 // Elide intervening MergeMem's
6046 while (n->is_MergeMem()) {
6047 n = n->as_MergeMem()->memory_at(alias_idx);
6048 }
6049 Compile* C = Compile::current();
6050 const TypePtr* n_adr_type = n->adr_type();
6051 if (n == m->empty_memory()) {
6052 // Implicit copy of base_memory()
6053 } else if (n_adr_type != TypePtr::BOTTOM) {
6054 assert(n_adr_type != nullptr, "new memory must have a well-defined adr_type");
6055 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
6056 } else {
6057 // A few places like make_runtime_call "know" that VM calls are narrow,
6058 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
6059 bool expected_wide_mem = false;
6060 if (n == m->base_memory()) {
6061 expected_wide_mem = true;
6062 } else if (alias_idx == Compile::AliasIdxRaw ||
6063 n == m->memory_at(Compile::AliasIdxRaw)) {
6064 expected_wide_mem = true;
6065 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
6066 // memory can "leak through" calls on channels that
6067 // are write-once. Allow this also.
6068 expected_wide_mem = true;
6069 }
6070 assert(expected_wide_mem, "expected narrow slice replacement");
6071 }
6072 }
6073 #else // !ASSERT
6074 #define verify_memory_slice(m,i,n) (void)(0) // PRODUCT version is no-op
6075 #endif
6076
6077
6078 //-----------------------------memory_at---------------------------------------
6079 Node* MergeMemNode::memory_at(uint alias_idx) const {
6080 assert(alias_idx >= Compile::AliasIdxRaw ||
6081 (alias_idx == Compile::AliasIdxBot && !Compile::current()->do_aliasing()),
6082 "must avoid base_memory and AliasIdxTop");
6083
6084 // Otherwise, it is a narrow slice.
6085 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
6086 if (is_empty_memory(n)) {
6087 // the array is sparse; empty slots are the "top" node
6088 n = base_memory();
6089 assert(Node::in_dump()
6090 || n == nullptr || n->bottom_type() == Type::TOP
6091 || n->adr_type() == nullptr // address is TOP
6092 || n->adr_type() == TypePtr::BOTTOM
6093 || n->adr_type() == TypeRawPtr::BOTTOM
6094 || !Compile::current()->do_aliasing(),
6095 "must be a wide memory");
6096 // do_aliasing == false if we are organizing the memory states manually.
6097 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
6098 } else {
6099 // make sure the stored slice is sane
6100 #ifdef ASSERT
6101 if (VMError::is_error_reported() || Node::in_dump()) {
6102 } else if (might_be_same(n, base_memory())) {
6103 // Give it a pass: It is a mostly harmless repetition of the base.
6104 // This can arise normally from node subsumption during optimization.
6105 } else {
6106 verify_memory_slice(this, alias_idx, n);
6107 }
6108 #endif
6109 }
6110 return n;
6111 }
6112
6113 //---------------------------set_memory_at-------------------------------------
6114 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
6115 verify_memory_slice(this, alias_idx, n);
6116 Node* empty_mem = empty_memory();
6117 if (n == base_memory()) n = empty_mem; // collapse default
6118 uint need_req = alias_idx+1;
6119 if (req() < need_req) {
6120 if (n == empty_mem) return; // already the default, so do not grow me
6121 // grow the sparse array
6122 do {
6123 add_req(empty_mem);
6124 } while (req() < need_req);
6125 }
6126 set_req( alias_idx, n );
6127 }
6128
6129
6130
6131 //--------------------------iteration_setup------------------------------------
6132 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
6133 if (other != nullptr) {
6134 grow_to_match(other);
6135 // invariant: the finite support of mm2 is within mm->req()
6136 #ifdef ASSERT
6137 for (uint i = req(); i < other->req(); i++) {
6138 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
6139 }
6140 #endif
6141 }
6142 // Replace spurious copies of base_memory by top.
6143 Node* base_mem = base_memory();
6144 if (base_mem != nullptr && !base_mem->is_top()) {
6145 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
6146 if (in(i) == base_mem)
6147 set_req(i, empty_memory());
6148 }
6149 }
6150 }
6151
6152 //---------------------------grow_to_match-------------------------------------
6153 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
6154 Node* empty_mem = empty_memory();
6155 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
6156 // look for the finite support of the other memory
6157 for (uint i = other->req(); --i >= req(); ) {
6158 if (other->in(i) != empty_mem) {
6159 uint new_len = i+1;
6160 while (req() < new_len) add_req(empty_mem);
6161 break;
6162 }
6163 }
6164 }
6165
6166 //---------------------------verify_sparse-------------------------------------
6167 #ifndef PRODUCT
6168 bool MergeMemNode::verify_sparse() const {
6169 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
6170 Node* base_mem = base_memory();
6171 // The following can happen in degenerate cases, since empty==top.
6172 if (is_empty_memory(base_mem)) return true;
6173 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
6174 assert(in(i) != nullptr, "sane slice");
6175 if (in(i) == base_mem) return false; // should have been the sentinel value!
6176 }
6177 return true;
6178 }
6179
6180 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
6181 Node* n;
6182 n = mm->in(idx);
6183 if (mem == n) return true; // might be empty_memory()
6184 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
6185 if (mem == n) return true;
6186 return false;
6187 }
6188 #endif // !PRODUCT