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