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