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.
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24 */
25
26 #include "classfile/javaClasses.hpp"
27 #include "compiler/compileLog.hpp"
28 #include "gc/shared/barrierSet.hpp"
29 #include "gc/shared/c2/barrierSetC2.hpp"
30 #include "gc/shared/tlab_globals.hpp"
31 #include "memory/allocation.inline.hpp"
32 #include "memory/resourceArea.hpp"
33 #include "oops/objArrayKlass.hpp"
34 #include "opto/addnode.hpp"
35 #include "opto/arraycopynode.hpp"
36 #include "opto/cfgnode.hpp"
37 #include "opto/compile.hpp"
38 #include "opto/connode.hpp"
39 #include "opto/convertnode.hpp"
40 #include "opto/loopnode.hpp"
41 #include "opto/machnode.hpp"
42 #include "opto/matcher.hpp"
43 #include "opto/memnode.hpp"
44 #include "opto/mempointer.hpp"
45 #include "opto/mulnode.hpp"
46 #include "opto/narrowptrnode.hpp"
47 #include "opto/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/globalDefinitions.hpp"
57 #include "utilities/macros.hpp"
58 #include "utilities/powerOfTwo.hpp"
59 #include "utilities/vmError.hpp"
60
61 // Portions of code courtesy of Clifford Click
62
63 // Optimization - Graph Style
64
65 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st);
66
67 //=============================================================================
68 uint MemNode::size_of() const { return sizeof(*this); }
69
70 const TypePtr *MemNode::adr_type() const {
71 Node* adr = in(Address);
72 if (adr == nullptr) return nullptr; // node is dead
73 const TypePtr* cross_check = nullptr;
74 DEBUG_ONLY(cross_check = _adr_type);
75 return calculate_adr_type(adr->bottom_type(), cross_check);
76 }
77
78 bool MemNode::check_if_adr_maybe_raw(Node* adr) {
79 if (adr != nullptr) {
80 if (adr->bottom_type()->base() == Type::RawPtr || adr->bottom_type()->base() == Type::AnyPtr) {
81 return true;
82 }
83 }
84 return false;
85 }
86
87 #ifndef PRODUCT
88 void MemNode::dump_spec(outputStream *st) const {
89 if (in(Address) == nullptr) {
90 // node is dead
91 return;
92 }
93 #ifndef ASSERT
94 // fake the missing field
95 const TypePtr* _adr_type = in(Address)->bottom_type()->isa_ptr();
96 #endif
97 dump_adr_type(_adr_type, st);
98
99 Compile* C = Compile::current();
100 if (C->alias_type(_adr_type)->is_volatile()) {
101 st->print(" Volatile!");
102 }
103 if (_unaligned_access) {
104 st->print(" unaligned");
105 }
106 if (_mismatched_access) {
107 st->print(" mismatched");
108 }
109 if (_unsafe_access) {
110 st->print(" unsafe");
111 }
112 st->print(" barrier(0x%x)", _barrier_data);
113 }
114
115 void MemNode::dump_adr_type(const TypePtr* adr_type, outputStream* st) {
116 st->print(" @");
117 if (adr_type == nullptr) {
118 st->print("null");
119 } else {
120 adr_type->dump_on(st);
121 Compile* C = Compile::current();
122 Compile::AliasType* atp = nullptr;
123 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type);
124 if (atp == nullptr)
125 st->print(", idx=?\?;");
126 else if (atp->index() == Compile::AliasIdxBot)
127 st->print(", idx=Bot;");
128 else if (atp->index() == Compile::AliasIdxTop)
129 st->print(", idx=Top;");
130 else if (atp->index() == Compile::AliasIdxRaw)
131 st->print(", idx=Raw;");
132 else {
133 ciField* field = atp->field();
134 if (field) {
135 st->print(", name=");
136 field->print_name_on(st);
137 }
138 st->print(", idx=%d;", atp->index());
139 }
140 }
141 }
142
143 extern void print_alias_types();
144
145 #endif
146
147 Node *MemNode::optimize_simple_memory_chain(Node *mchain, const TypeOopPtr *t_oop, Node *load, PhaseGVN *phase) {
148 assert((t_oop != nullptr), "sanity");
149 bool is_instance = t_oop->is_known_instance_field();
150 bool is_boxed_value_load = t_oop->is_ptr_to_boxed_value() &&
151 (load != nullptr) && load->is_Load() &&
152 (phase->is_IterGVN() != nullptr);
153 if (!(is_instance || is_boxed_value_load))
154 return mchain; // don't try to optimize non-instance types
155 uint instance_id = t_oop->instance_id();
156 Node *start_mem = phase->C->start()->proj_out_or_null(TypeFunc::Memory);
157 Node *prev = nullptr;
158 Node *result = mchain;
159 while (prev != result) {
160 prev = result;
161 if (result == start_mem)
162 break; // hit one of our sentinels
163 // skip over a call which does not affect this memory slice
164 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {
165 Node *proj_in = result->in(0);
166 if (proj_in->is_Allocate() && proj_in->_idx == instance_id) {
167 break; // hit one of our sentinels
168 } else if (proj_in->is_Call()) {
169 // ArrayCopyNodes processed here as well
170 CallNode *call = proj_in->as_Call();
171 if (!call->may_modify(t_oop, phase)) { // returns false for instances
172 result = call->in(TypeFunc::Memory);
173 }
174 } else if (proj_in->is_Initialize()) {
175 AllocateNode* alloc = proj_in->as_Initialize()->allocation();
176 // Stop if this is the initialization for the object instance which
177 // contains this memory slice, otherwise skip over it.
178 if ((alloc == nullptr) || (alloc->_idx == instance_id)) {
179 break;
180 }
181 if (is_instance) {
182 result = proj_in->in(TypeFunc::Memory);
183 } else if (is_boxed_value_load) {
184 Node* klass = alloc->in(AllocateNode::KlassNode);
185 const TypeKlassPtr* tklass = phase->type(klass)->is_klassptr();
186 if (tklass->klass_is_exact() && !tklass->exact_klass()->equals(t_oop->is_instptr()->exact_klass())) {
187 result = proj_in->in(TypeFunc::Memory); // not related allocation
188 }
189 }
190 } else if (proj_in->is_MemBar()) {
191 ArrayCopyNode* ac = nullptr;
192 if (ArrayCopyNode::may_modify(t_oop, proj_in->as_MemBar(), phase, ac)) {
193 break;
194 }
195 result = proj_in->in(TypeFunc::Memory);
196 } else if (proj_in->is_top()) {
197 break; // dead code
198 } else {
199 assert(false, "unexpected projection");
200 }
201 } else if (result->is_ClearArray()) {
202 if (!is_instance || !ClearArrayNode::step_through(&result, instance_id, phase)) {
203 // Can not bypass initialization of the instance
204 // we are looking for.
205 break;
206 }
207 // Otherwise skip it (the call updated 'result' value).
208 } else if (result->is_MergeMem()) {
209 result = step_through_mergemem(phase, result->as_MergeMem(), t_oop, nullptr, tty);
210 }
211 }
212 return result;
213 }
214
215 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, Node *load, PhaseGVN *phase) {
216 const TypeOopPtr* t_oop = t_adr->isa_oopptr();
217 if (t_oop == nullptr)
218 return mchain; // don't try to optimize non-oop types
219 Node* result = optimize_simple_memory_chain(mchain, t_oop, load, phase);
220 bool is_instance = t_oop->is_known_instance_field();
221 PhaseIterGVN *igvn = phase->is_IterGVN();
222 if (is_instance && igvn != nullptr && result->is_Phi()) {
223 PhiNode *mphi = result->as_Phi();
224 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
225 const TypePtr *t = mphi->adr_type();
226 bool do_split = false;
227 // In the following cases, Load memory input can be further optimized based on
228 // its precise address type
229 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ) {
230 do_split = true;
231 } else if (t->isa_oopptr() && !t->is_oopptr()->is_known_instance()) {
232 const TypeOopPtr* mem_t =
233 t->is_oopptr()->cast_to_exactness(true)
234 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
235 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id());
236 if (t_oop->isa_aryptr()) {
237 mem_t = mem_t->is_aryptr()
238 ->cast_to_stable(t_oop->is_aryptr()->is_stable())
239 ->cast_to_size(t_oop->is_aryptr()->size())
240 ->with_offset(t_oop->is_aryptr()->offset())
241 ->is_aryptr();
242 }
243 do_split = mem_t == t_oop;
244 }
245 if (do_split) {
246 // clone the Phi with our address type
247 result = mphi->split_out_instance(t_adr, igvn);
248 } else {
249 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain");
250 }
251 }
252 return result;
253 }
254
255 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) {
256 uint alias_idx = phase->C->get_alias_index(tp);
257 Node *mem = mmem;
258 #ifdef ASSERT
259 {
260 // Check that current type is consistent with the alias index used during graph construction
261 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
262 bool consistent = adr_check == nullptr || adr_check->empty() ||
263 phase->C->must_alias(adr_check, alias_idx );
264 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
265 if( !consistent && adr_check != nullptr && !adr_check->empty() &&
266 tp->isa_aryptr() && tp->offset() == Type::OffsetBot &&
267 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot &&
268 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() ||
269 adr_check->offset() == oopDesc::klass_offset_in_bytes() ||
270 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) {
271 // don't assert if it is dead code.
272 consistent = true;
273 }
274 if( !consistent ) {
275 st->print("alias_idx==%d, adr_check==", alias_idx);
276 if( adr_check == nullptr ) {
277 st->print("null");
278 } else {
279 adr_check->dump();
280 }
281 st->cr();
282 print_alias_types();
283 assert(consistent, "adr_check must match alias idx");
284 }
285 }
286 #endif
287 // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally
288 // means an array I have not precisely typed yet. Do not do any
289 // alias stuff with it any time soon.
290 const TypeOopPtr *toop = tp->isa_oopptr();
291 if (tp->base() != Type::AnyPtr &&
292 !(toop &&
293 toop->isa_instptr() &&
294 toop->is_instptr()->instance_klass()->is_java_lang_Object() &&
295 toop->offset() == Type::OffsetBot)) {
296 // IGVN _delay_transform may be set to true and if that is the case and mmem
297 // is already a registered node then the validation inside transform will
298 // complain.
299 Node* m = mmem;
300 PhaseIterGVN* igvn = phase->is_IterGVN();
301 if (igvn == nullptr || !igvn->delay_transform()) {
302 // compress paths and change unreachable cycles to TOP
303 // If not, we can update the input infinitely along a MergeMem cycle
304 // Equivalent code in PhiNode::Ideal
305 m = phase->transform(mmem);
306 }
307 // If transformed to a MergeMem, get the desired slice
308 // Otherwise the returned node represents memory for every slice
309 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
310 // Update input if it is progress over what we have now
311 }
312 return mem;
313 }
314
315 //--------------------------Ideal_common---------------------------------------
316 // Look for degenerate control and memory inputs. Bypass MergeMem inputs.
317 // Unhook non-raw memories from complete (macro-expanded) initializations.
318 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
319 // If our control input is a dead region, kill all below the region
320 Node *ctl = in(MemNode::Control);
321 if (ctl && remove_dead_region(phase, can_reshape))
322 return this;
323 ctl = in(MemNode::Control);
324 // Don't bother trying to transform a dead node
325 if (ctl && ctl->is_top()) return NodeSentinel;
326
327 PhaseIterGVN *igvn = phase->is_IterGVN();
328 // Wait if control on the worklist.
329 if (ctl && can_reshape && igvn != nullptr) {
330 Node* bol = nullptr;
331 Node* cmp = nullptr;
332 if (ctl->in(0)->is_If()) {
333 assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity");
334 bol = ctl->in(0)->in(1);
335 if (bol->is_Bool())
336 cmp = ctl->in(0)->in(1)->in(1);
337 }
338 if (igvn->_worklist.member(ctl) ||
339 (bol != nullptr && igvn->_worklist.member(bol)) ||
340 (cmp != nullptr && igvn->_worklist.member(cmp)) ) {
341 // This control path may be dead.
342 // Delay this memory node transformation until the control is processed.
343 igvn->_worklist.push(this);
344 return NodeSentinel; // caller will return null
345 }
346 }
347 // Ignore if memory is dead, or self-loop
348 Node *mem = in(MemNode::Memory);
349 if (phase->type( mem ) == Type::TOP) return NodeSentinel; // caller will return null
350 assert(mem != this, "dead loop in MemNode::Ideal");
351
352 if (can_reshape && igvn != nullptr && igvn->_worklist.member(mem)) {
353 // This memory slice may be dead.
354 // Delay this mem node transformation until the memory is processed.
355 igvn->_worklist.push(this);
356 return NodeSentinel; // caller will return null
357 }
358
359 Node *address = in(MemNode::Address);
360 const Type *t_adr = phase->type(address);
361 if (t_adr == Type::TOP) return NodeSentinel; // caller will return null
362
363 if (can_reshape && is_unsafe_access() && (t_adr == TypePtr::NULL_PTR)) {
364 // Unsafe off-heap access with zero address. Remove access and other control users
365 // to not confuse optimizations and add a HaltNode to fail if this is ever executed.
366 assert(ctl != nullptr, "unsafe accesses should be control dependent");
367 for (DUIterator_Fast imax, i = ctl->fast_outs(imax); i < imax; i++) {
368 Node* u = ctl->fast_out(i);
369 if (u != ctl) {
370 igvn->rehash_node_delayed(u);
371 int nb = u->replace_edge(ctl, phase->C->top(), igvn);
372 --i, imax -= nb;
373 }
374 }
375 Node* frame = igvn->transform(new ParmNode(phase->C->start(), TypeFunc::FramePtr));
376 Node* halt = igvn->transform(new HaltNode(ctl, frame, "unsafe off-heap access with zero address"));
377 phase->C->root()->add_req(halt);
378 return this;
379 }
380
381 if (can_reshape && igvn != nullptr &&
382 (igvn->_worklist.member(address) ||
383 (igvn->_worklist.size() > 0 && t_adr != adr_type())) ) {
384 // The address's base and type may change when the address is processed.
385 // Delay this mem node transformation until the address is processed.
386 igvn->_worklist.push(this);
387 return NodeSentinel; // caller will return null
388 }
389
390 // Do NOT remove or optimize the next lines: ensure a new alias index
391 // is allocated for an oop pointer type before Escape Analysis.
392 // Note: C++ will not remove it since the call has side effect.
393 if (t_adr->isa_oopptr()) {
394 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr());
395 }
396
397 Node* base = nullptr;
398 if (address->is_AddP()) {
399 base = address->in(AddPNode::Base);
400 }
401 if (base != nullptr && phase->type(base)->higher_equal(TypePtr::NULL_PTR) &&
402 !t_adr->isa_rawptr()) {
403 // Note: raw address has TOP base and top->higher_equal(TypePtr::NULL_PTR) is true.
404 // Skip this node optimization if its address has TOP base.
405 return NodeSentinel; // caller will return null
406 }
407
408 // Avoid independent memory operations
409 Node* old_mem = mem;
410
411 // The code which unhooks non-raw memories from complete (macro-expanded)
412 // initializations was removed. After macro-expansion all stores caught
413 // by Initialize node became raw stores and there is no information
414 // which memory slices they modify. So it is unsafe to move any memory
415 // operation above these stores. Also in most cases hooked non-raw memories
416 // were already unhooked by using information from detect_ptr_independence()
417 // and find_previous_store().
418
419 if (mem->is_MergeMem()) {
420 MergeMemNode* mmem = mem->as_MergeMem();
421 const TypePtr *tp = t_adr->is_ptr();
422
423 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
424 }
425
426 if (mem != old_mem) {
427 set_req_X(MemNode::Memory, mem, phase);
428 if (phase->type(mem) == Type::TOP) return NodeSentinel;
429 return this;
430 }
431
432 // let the subclass continue analyzing...
433 return nullptr;
434 }
435
436 // Helper function for proving some simple control dominations.
437 // Attempt to prove that all control inputs of 'dom' dominate 'sub'.
438 // Already assumes that 'dom' is available at 'sub', and that 'sub'
439 // is not a constant (dominated by the method's StartNode).
440 // Used by MemNode::find_previous_store to prove that the
441 // control input of a memory operation predates (dominates)
442 // an allocation it wants to look past.
443 // Returns 'DomResult::Dominate' if all control inputs of 'dom'
444 // dominate 'sub', 'DomResult::NotDominate' if not,
445 // and 'DomResult::EncounteredDeadCode' if we can't decide due to
446 // dead code, but at the end of IGVN, we know the definite result
447 // once the dead code is cleaned up.
448 Node::DomResult MemNode::maybe_all_controls_dominate(Node* dom, Node* sub, PhaseGVN* phase) {
449 if (dom == nullptr || dom->is_top() || sub == nullptr || sub->is_top()) {
450 return DomResult::EncounteredDeadCode; // Conservative answer for dead code
451 }
452
453 // Check 'dom'. Skip Proj and CatchProj nodes.
454 dom = dom->find_exact_control(dom);
455 if (dom == nullptr || dom->is_top()) {
456 return DomResult::EncounteredDeadCode; // Conservative answer for dead code
457 }
458
459 if (dom == sub) {
460 // For the case when, for example, 'sub' is Initialize and the original
461 // 'dom' is Proj node of the 'sub'.
462 return DomResult::NotDominate;
463 }
464
465 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub) {
466 return DomResult::Dominate;
467 }
468
469 // 'dom' dominates 'sub' if its control edge and control edges
470 // of all its inputs dominate or equal to sub's control edge.
471
472 // Currently 'sub' is either Allocate, Initialize or Start nodes.
473 // Or Region for the check in LoadNode::Ideal();
474 // 'sub' should have sub->in(0) != nullptr.
475 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() ||
476 sub->is_Region() || sub->is_Call(), "expecting only these nodes");
477
478 // Get control edge of 'sub'.
479 Node* orig_sub = sub;
480 sub = sub->find_exact_control(sub->in(0));
481 if (sub == nullptr || sub->is_top()) {
482 return DomResult::EncounteredDeadCode; // Conservative answer for dead code
483 }
484
485 assert(sub->is_CFG(), "expecting control");
486
487 if (sub == dom) {
488 return DomResult::Dominate;
489 }
490
491 if (sub->is_Start() || sub->is_Root()) {
492 return DomResult::NotDominate;
493 }
494
495 {
496 // Check all control edges of 'dom'.
497
498 ResourceMark rm;
499 Node_List nlist;
500 Unique_Node_List dom_list;
501
502 dom_list.push(dom);
503 bool only_dominating_controls = false;
504
505 for (uint next = 0; next < dom_list.size(); next++) {
506 Node* n = dom_list.at(next);
507 if (n == orig_sub) {
508 return DomResult::NotDominate; // One of dom's inputs dominated by sub.
509 }
510 if (!n->is_CFG() && n->pinned()) {
511 // Check only own control edge for pinned non-control nodes.
512 n = n->find_exact_control(n->in(0));
513 if (n == nullptr || n->is_top()) {
514 return DomResult::EncounteredDeadCode; // Conservative answer for dead code
515 }
516 assert(n->is_CFG(), "expecting control");
517 dom_list.push(n);
518 } else if (n->is_Con() || n->is_Start() || n->is_Root()) {
519 only_dominating_controls = true;
520 } else if (n->is_CFG()) {
521 DomResult dom_result = n->dominates(sub, nlist);
522 if (dom_result == DomResult::Dominate) {
523 only_dominating_controls = true;
524 } else {
525 return dom_result;
526 }
527 } else {
528 if (n->Value(phase) == Type::TOP) {
529 return DomResult::EncounteredDeadCode;
530 }
531 // First, own control edge.
532 Node* m = n->find_exact_control(n->in(0));
533 if (m != nullptr) {
534 if (m->is_top()) {
535 return DomResult::EncounteredDeadCode; // Conservative answer for dead code
536 }
537 dom_list.push(m);
538 }
539 // Now, the rest of edges.
540 uint cnt = n->req();
541 for (uint i = 1; i < cnt; i++) {
542 m = n->find_exact_control(n->in(i));
543 if (m == nullptr || m->is_top()) {
544 continue;
545 }
546 dom_list.push(m);
547 }
548 }
549 }
550 return only_dominating_controls ? DomResult::Dominate : DomResult::NotDominate;
551 }
552 }
553
554 //---------------------detect_ptr_independence---------------------------------
555 // Used by MemNode::find_previous_store to prove that two base
556 // pointers are never equal.
557 // The pointers are accompanied by their associated allocations,
558 // if any, which have been previously discovered by the caller.
559 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
560 Node* p2, AllocateNode* a2,
561 PhaseGVN* phase) {
562 // Trivial case: Non-overlapping values. Be careful, we can cast a raw pointer to an oop (e.g. in
563 // the allocation pattern) so joining the types only works if both are oops. join may also give
564 // an incorrect result when both pointers are nullable and the result is supposed to be
565 // TypePtr::NULL_PTR, so we exclude that case.
566 const Type* p1_type = p1->bottom_type();
567 const Type* p2_type = p2->bottom_type();
568 if (p1_type != p2_type && p1_type->isa_oopptr() && p2_type->isa_oopptr() &&
569 (!p1_type->maybe_null() || !p2_type->maybe_null()) &&
570 p1_type->join(p2_type)->empty()) {
571 return true;
572 }
573
574 // Attempt to prove that these two pointers cannot be aliased.
575 // They may both manifestly be allocations, and they should differ.
576 // Or, if they are not both allocations, they can be distinct constants.
577 // Otherwise, one is an allocation and the other a pre-existing value.
578 if (a1 == nullptr && a2 == nullptr) { // neither an allocation
579 return (p1 != p2) && p1->is_Con() && p2->is_Con();
580 } else if (a1 != nullptr && a2 != nullptr) { // both allocations
581 return (a1 != a2);
582 } else if (a1 != nullptr) { // one allocation a1
583 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.)
584 return all_controls_dominate(p2->uncast(), a1, phase);
585 } else { //(a2 != null) // one allocation a2
586 return all_controls_dominate(p1->uncast(), a2, phase);
587 }
588 return false;
589 }
590
591 // Find an arraycopy ac that produces the memory state represented by parameter mem.
592 // Return ac if
593 // (a) can_see_stored_value=true and ac must have set the value for this load or if
594 // (b) can_see_stored_value=false and ac could have set the value for this load or if
595 // (c) can_see_stored_value=false and ac cannot have set the value for this load.
596 // In case (c) change the parameter mem to the memory input of ac to skip it
597 // when searching stored value.
598 // Otherwise return null.
599 Node* LoadNode::find_previous_arraycopy(PhaseValues* phase, Node* ld_alloc, Node*& mem, bool can_see_stored_value) const {
600 ArrayCopyNode* ac = find_array_copy_clone(ld_alloc, mem);
601 if (ac != nullptr) {
602 Node* ld_addp = in(MemNode::Address);
603 Node* src = ac->in(ArrayCopyNode::Src);
604 const TypeAryPtr* ary_t = phase->type(src)->isa_aryptr();
605
606 // This is a load from a cloned array. The corresponding arraycopy ac must
607 // have set the value for the load and we can return ac but only if the load
608 // is known to be within bounds. This is checked below.
609 if (ary_t != nullptr && ld_addp->is_AddP()) {
610 Node* ld_offs = ld_addp->in(AddPNode::Offset);
611 BasicType ary_elem = ary_t->elem()->array_element_basic_type();
612 jlong header = arrayOopDesc::base_offset_in_bytes(ary_elem);
613 jlong elemsize = type2aelembytes(ary_elem);
614
615 const TypeX* ld_offs_t = phase->type(ld_offs)->isa_intptr_t();
616 const TypeInt* sizetype = ary_t->size();
617
618 if (ld_offs_t->_lo >= header && ld_offs_t->_hi < (sizetype->_lo * elemsize + header)) {
619 // The load is known to be within bounds. It receives its value from ac.
620 return ac;
621 }
622 // The load is known to be out-of-bounds.
623 }
624 // The load could be out-of-bounds. It must not be hoisted but must remain
625 // dependent on the runtime range check. This is achieved by returning null.
626 } else if (mem->is_Proj() && mem->in(0) != nullptr && mem->in(0)->is_ArrayCopy()) {
627 ArrayCopyNode* ac = mem->in(0)->as_ArrayCopy();
628
629 if (ac->is_arraycopy_validated() ||
630 ac->is_copyof_validated() ||
631 ac->is_copyofrange_validated()) {
632 Node* ld_addp = in(MemNode::Address);
633 if (ld_addp->is_AddP()) {
634 Node* ld_base = ld_addp->in(AddPNode::Address);
635 Node* ld_offs = ld_addp->in(AddPNode::Offset);
636
637 Node* dest = ac->in(ArrayCopyNode::Dest);
638
639 if (dest == ld_base) {
640 const TypeX* ld_offs_t = phase->type(ld_offs)->isa_intptr_t();
641 assert(!ld_offs_t->empty(), "dead reference should be checked already");
642 // Take into account vector or unsafe access size
643 jlong ld_size_in_bytes = (jlong)memory_size();
644 jlong offset_hi = ld_offs_t->_hi + ld_size_in_bytes - 1;
645 offset_hi = MIN2(offset_hi, (jlong)(TypeX::MAX->_hi)); // Take care for overflow in 32-bit VM
646 if (ac->modifies(ld_offs_t->_lo, (intptr_t)offset_hi, phase, can_see_stored_value)) {
647 return ac;
648 }
649 if (!can_see_stored_value) {
650 mem = ac->in(TypeFunc::Memory);
651 return ac;
652 }
653 }
654 }
655 }
656 }
657 return nullptr;
658 }
659
660 ArrayCopyNode* MemNode::find_array_copy_clone(Node* ld_alloc, Node* mem) const {
661 if (mem->is_Proj() && mem->in(0) != nullptr && (mem->in(0)->Opcode() == Op_MemBarStoreStore ||
662 mem->in(0)->Opcode() == Op_MemBarCPUOrder)) {
663 if (ld_alloc != nullptr) {
664 // Check if there is an array copy for a clone
665 Node* mb = mem->in(0);
666 ArrayCopyNode* ac = nullptr;
667 if (mb->in(0) != nullptr && mb->in(0)->is_Proj() &&
668 mb->in(0)->in(0) != nullptr && mb->in(0)->in(0)->is_ArrayCopy()) {
669 ac = mb->in(0)->in(0)->as_ArrayCopy();
670 } else {
671 // Step over GC barrier when ReduceInitialCardMarks is disabled
672 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
673 Node* control_proj_ac = bs->step_over_gc_barrier(mb->in(0));
674
675 if (control_proj_ac->is_Proj() && control_proj_ac->in(0)->is_ArrayCopy()) {
676 ac = control_proj_ac->in(0)->as_ArrayCopy();
677 }
678 }
679
680 if (ac != nullptr && ac->is_clonebasic()) {
681 AllocateNode* alloc = AllocateNode::Ideal_allocation(ac->in(ArrayCopyNode::Dest));
682 if (alloc != nullptr && alloc == ld_alloc) {
683 return ac;
684 }
685 }
686 }
687 }
688 return nullptr;
689 }
690
691 // The logic for reordering loads and stores uses four steps:
692 // (a) Walk carefully past stores and initializations which we
693 // can prove are independent of this load.
694 // (b) Observe that the next memory state makes an exact match
695 // with self (load or store), and locate the relevant store.
696 // (c) Ensure that, if we were to wire self directly to the store,
697 // the optimizer would fold it up somehow.
698 // (d) Do the rewiring, and return, depending on some other part of
699 // the optimizer to fold up the load.
700 // This routine handles steps (a) and (b). Steps (c) and (d) are
701 // specific to loads and stores, so they are handled by the callers.
702 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.)
703 //
704 Node* MemNode::find_previous_store(PhaseGVN* phase) {
705 AccessAnalyzer analyzer(phase, this);
706
707 Node* mem = in(MemNode::Memory); // start searching here...
708 int cnt = 50; // Cycle limiter
709 for (;; cnt--) {
710 // While we can dance past unrelated stores...
711 if (phase->type(mem) == Type::TOP) {
712 // Encounter a dead node
713 return phase->C->top();
714 } else if (cnt <= 0) {
715 // Caught in cycle or a complicated dance?
716 return nullptr;
717 } else if (mem->is_Phi()) {
718 return nullptr;
719 }
720
721 AccessAnalyzer::AccessIndependence independence = analyzer.detect_access_independence(mem);
722 if (independence.independent) {
723 // (a) advance through the independent store
724 mem = independence.mem;
725 assert(mem != nullptr, "must not be nullptr");
726 } else {
727 // (b) found the store that this access observes if this is not null
728 // Otherwise, give up if it is null
729 return independence.mem;
730 }
731 }
732
733 return nullptr; // bail out
734 }
735
736 //----------------------calculate_adr_type-------------------------------------
737 // Helper function. Notices when the given type of address hits top or bottom.
738 // Also, asserts a cross-check of the type against the expected address type.
739 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
740 if (t == Type::TOP) return nullptr; // does not touch memory any more?
741 #ifdef ASSERT
742 if (!VerifyAliases || VMError::is_error_reported() || Node::in_dump()) cross_check = nullptr;
743 #endif
744 const TypePtr* tp = t->isa_ptr();
745 if (tp == nullptr) {
746 assert(cross_check == nullptr || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
747 return TypePtr::BOTTOM; // touches lots of memory
748 } else {
749 #ifdef ASSERT
750 // %%%% [phh] We don't check the alias index if cross_check is
751 // TypeRawPtr::BOTTOM. Needs to be investigated.
752 if (cross_check != nullptr &&
753 cross_check != TypePtr::BOTTOM &&
754 cross_check != TypeRawPtr::BOTTOM) {
755 // Recheck the alias index, to see if it has changed (due to a bug).
756 Compile* C = Compile::current();
757 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
758 "must stay in the original alias category");
759 // The type of the address must be contained in the adr_type,
760 // disregarding "null"-ness.
761 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
762 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
763 assert(cross_check->meet(tp_notnull) == cross_check->remove_speculative(),
764 "real address must not escape from expected memory type");
765 }
766 #endif
767 return tp;
768 }
769 }
770
771 uint8_t MemNode::barrier_data(const Node* n) {
772 if (n->is_LoadStore()) {
773 return n->as_LoadStore()->barrier_data();
774 } else if (n->is_Mem()) {
775 return n->as_Mem()->barrier_data();
776 }
777 return 0;
778 }
779
780 AccessAnalyzer::AccessAnalyzer(PhaseGVN* phase, MemNode* n)
781 : _phase(phase), _n(n), _memory_size(n->memory_size()), _alias_idx(-1) {
782 Node* adr = _n->in(MemNode::Address);
783 _offset = 0;
784 _base = AddPNode::Ideal_base_and_offset(adr, _phase, _offset);
785 _maybe_raw = MemNode::check_if_adr_maybe_raw(adr);
786 _alloc = AllocateNode::Ideal_allocation(_base);
787 _adr_type = _n->adr_type();
788
789 if (_adr_type != nullptr && _adr_type->base() != TypePtr::AnyPtr) {
790 // Avoid the cases that will upset Compile::get_alias_index
791 _alias_idx = _phase->C->get_alias_index(_adr_type);
792 assert(_alias_idx != Compile::AliasIdxTop, "must not be a dead node");
793 assert(_alias_idx != Compile::AliasIdxBot || !phase->C->do_aliasing(), "must not be a very wide access");
794 }
795 }
796
797 // Decide whether the memory accessed by '_n' and 'other' may overlap. This function may be used
798 // when we want to walk the memory graph to fold a load, or when we want to hoist a load above a
799 // loop when there are no stores that may overlap with the load inside the loop.
800 AccessAnalyzer::AccessIndependence AccessAnalyzer::detect_access_independence(Node* other) const {
801 assert(_phase->type(other) == Type::MEMORY, "must be a memory node %s", other->Name());
802 assert(!other->is_Phi(), "caller must handle Phi");
803
804 if (_adr_type == nullptr) {
805 // This means the access is dead
806 return {false, _phase->C->top()};
807 } else if (_adr_type->base() == TypePtr::AnyPtr) {
808 // An example for this case is an access into the memory address 0 performed using Unsafe
809 assert(_adr_type->ptr() == TypePtr::Null, "MemNode should never access a wide memory");
810 return {false, nullptr};
811 }
812
813 if (_offset == Type::OffsetBot) {
814 // cannot unalias unless there are precise offsets
815 return {false, nullptr};
816 }
817
818 const TypeOopPtr* adr_oop_type = _adr_type->isa_oopptr();
819 Node* prev = other;
820 if (other->is_Store()) {
821 Node* st_adr = other->in(MemNode::Address);
822 intptr_t st_offset = 0;
823 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, _phase, st_offset);
824 if (st_base == nullptr) {
825 // inscrutable pointer
826 return {false, nullptr};
827 }
828
829 // If the bases are the same and the offsets are the same, it seems that this is the exact
830 // store we are looking for, the caller will check if the type of the store matches using
831 // MemNode::can_see_stored_value
832 if (st_base == _base && st_offset == _offset) {
833 return {false, other};
834 }
835
836 // If it is provable that the memory accessed by 'other' does not overlap the memory accessed
837 // by '_n', we may walk past 'other'.
838 // For raw accesses, 2 accesses are independent if they have the same base and the offsets
839 // say that they do not overlap.
840 // For heap accesses, 2 accesses are independent if either the bases are provably different
841 // at runtime or the offsets say that the accesses do not overlap.
842 if ((_maybe_raw || MemNode::check_if_adr_maybe_raw(st_adr)) && st_base != _base) {
843 // Raw accesses can only be provably independent if they have the same base
844 return {false, nullptr};
845 }
846
847 // If the offsets say that the accesses do not overlap, then it is provable that 'other' and
848 // '_n' do not overlap. For example, a LoadI from Object+8 is independent from a StoreL into
849 // Object+12, no matter what the bases are.
850 if (st_offset != _offset && st_offset != Type::OffsetBot) {
851 const int MAX_STORE = MAX2(BytesPerLong, (int)MaxVectorSize);
852 assert(other->as_Store()->memory_size() <= MAX_STORE, "");
853 if (st_offset >= _offset + _memory_size ||
854 st_offset <= _offset - MAX_STORE ||
855 st_offset <= _offset - other->as_Store()->memory_size()) {
856 // Success: The offsets are provably independent.
857 // (You may ask, why not just test st_offset != offset and be done?
858 // The answer is that stores of different sizes can co-exist
859 // in the same sequence of RawMem effects. We sometimes initialize
860 // a whole 'tile' of array elements with a single jint or jlong.)
861 return {true, other->in(MemNode::Memory)};
862 }
863 }
864
865 // Same base and overlapping offsets, it seems provable that the accesses overlap, give up
866 if (st_base == _base) {
867 return {false, nullptr};
868 }
869
870 // Try to prove that 2 different base nodes at compile time are different values at runtime
871 bool known_independent = false;
872 if (MemNode::detect_ptr_independence(_base, _alloc, st_base, AllocateNode::Ideal_allocation(st_base), _phase)) {
873 known_independent = true;
874 }
875
876 if (known_independent) {
877 return {true, other->in(MemNode::Memory)};
878 }
879 } else if (other->is_Proj() && other->in(0)->is_Initialize()) {
880 InitializeNode* st_init = other->in(0)->as_Initialize();
881 AllocateNode* st_alloc = st_init->allocation();
882 if (st_alloc == nullptr) {
883 // Something degenerated
884 return {false, nullptr};
885 }
886 bool known_identical = false;
887 bool known_independent = false;
888 if (_alloc == st_alloc) {
889 known_identical = true;
890 } else if (_alloc != nullptr) {
891 known_independent = true;
892 } else if (MemNode::all_controls_dominate(_base->uncast(), st_alloc, _phase)) {
893 known_independent = true;
894 }
895
896 if (known_independent) {
897 // The bases are provably independent: Either they are
898 // manifestly distinct allocations, or else the control
899 // of _base dominates the store's allocation.
900 if (_alias_idx == Compile::AliasIdxRaw) {
901 other = st_alloc->in(TypeFunc::Memory);
902 } else {
903 other = st_init->memory(_alias_idx);
904 }
905 return {true, other};
906 }
907
908 // If we are not looking at a store initializing the same
909 // allocation we are loading from, we lose.
910 if (known_identical) {
911 // From caller, can_see_stored_value will consult find_captured_store.
912 return {false, other};
913 }
914
915 } else if (_n->find_previous_arraycopy(_phase, _alloc, other, false) != nullptr) {
916 // Find an arraycopy that may or may not affect the MemNode
917 return {prev != other, other};
918 } else if (other->is_MergeMem()) {
919 return {true, other->as_MergeMem()->memory_at(_alias_idx)};
920 } else if (adr_oop_type != nullptr && adr_oop_type->is_known_instance_field()) {
921 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
922 if (other->is_Proj() && other->in(0)->is_Call()) {
923 // ArrayCopyNodes processed here as well.
924 CallNode* call = other->in(0)->as_Call();
925 if (!call->may_modify(adr_oop_type, _phase)) {
926 return {true, call->in(TypeFunc::Memory)};
927 }
928 } else if (other->is_Proj() && other->in(0)->is_MemBar()) {
929 ArrayCopyNode* ac = nullptr;
930 if (!ArrayCopyNode::may_modify(adr_oop_type, other->in(0)->as_MemBar(), _phase, ac)) {
931 return {true, other->in(0)->in(TypeFunc::Memory)};
932 }
933 } else if (other->is_ClearArray()) {
934 if (ClearArrayNode::step_through(&other, (uint)adr_oop_type->instance_id(), _phase)) {
935 // (the call updated 'other' value)
936 return {true, other};
937 } else {
938 // Can not bypass initialization of the instance
939 // we are looking for.
940 return {false, other};
941 }
942 }
943 }
944
945 return {false, nullptr};
946 }
947
948 //=============================================================================
949 // Should LoadNode::Ideal() attempt to remove control edges?
950 bool LoadNode::can_remove_control() const {
951 return !has_pinned_control_dependency();
952 }
953 uint LoadNode::size_of() const { return sizeof(*this); }
954 bool LoadNode::cmp(const Node &n) const {
955 LoadNode& load = (LoadNode &)n;
956 return Type::equals(_type, load._type) &&
957 _control_dependency == load._control_dependency &&
958 _mo == load._mo;
959 }
960 const Type *LoadNode::bottom_type() const { return _type; }
961 uint LoadNode::ideal_reg() const {
962 return _type->ideal_reg();
963 }
964
965 #ifndef PRODUCT
966 void LoadNode::dump_spec(outputStream *st) const {
967 MemNode::dump_spec(st);
968 if( !Verbose && !WizardMode ) {
969 // standard dump does this in Verbose and WizardMode
970 st->print(" #"); _type->dump_on(st);
971 }
972 if (in(0) != nullptr && !depends_only_on_test()) {
973 st->print(" (does not depend only on test, ");
974 if (control_dependency() == UnknownControl) {
975 st->print("unknown control");
976 } else if (control_dependency() == Pinned) {
977 st->print("pinned");
978 } else if (adr_type() == TypeRawPtr::BOTTOM) {
979 st->print("raw access");
980 } else {
981 st->print("unknown reason");
982 }
983 st->print(")");
984 }
985 }
986 #endif
987
988 #ifdef ASSERT
989 //----------------------------is_immutable_value-------------------------------
990 // Helper function to allow a raw load without control edge for some cases
991 bool LoadNode::is_immutable_value(Node* adr) {
992 if (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() &&
993 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal) {
994
995 jlong offset = adr->in(AddPNode::Offset)->find_intptr_t_con(-1);
996 int offsets[] = {
997 in_bytes(JavaThread::osthread_offset()),
998 in_bytes(JavaThread::threadObj_offset()),
999 in_bytes(JavaThread::vthread_offset()),
1000 in_bytes(JavaThread::scopedValueCache_offset()),
1001 };
1002
1003 for (size_t i = 0; i < sizeof offsets / sizeof offsets[0]; i++) {
1004 if (offset == offsets[i]) {
1005 return true;
1006 }
1007 }
1008 }
1009
1010 return false;
1011 }
1012 #endif
1013
1014 //----------------------------LoadNode::make-----------------------------------
1015 // Polymorphic factory method:
1016 Node* LoadNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, BasicType bt, MemOrd mo,
1017 ControlDependency control_dependency, bool require_atomic_access, bool unaligned, bool mismatched, bool unsafe, uint8_t barrier_data) {
1018 Compile* C = gvn.C;
1019 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");
1020
1021 // sanity check the alias category against the created node type
1022 assert(!(adr_type->isa_oopptr() &&
1023 adr_type->offset() == oopDesc::klass_offset_in_bytes()),
1024 "use LoadKlassNode instead");
1025 assert(!(adr_type->isa_aryptr() &&
1026 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
1027 "use LoadRangeNode instead");
1028 // Check control edge of raw loads
1029 assert( ctl != nullptr || C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
1030 // oop will be recorded in oop map if load crosses safepoint
1031 rt->isa_oopptr() || is_immutable_value(adr),
1032 "raw memory operations should have control edge");
1033 LoadNode* load = nullptr;
1034 switch (bt) {
1035 case T_BOOLEAN: load = new LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
1036 case T_BYTE: load = new LoadBNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
1037 case T_INT: load = new LoadINode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
1038 case T_CHAR: load = new LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
1039 case T_SHORT: load = new LoadSNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
1040 case T_LONG: load = new LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency, require_atomic_access); break;
1041 case T_FLOAT: load = new LoadFNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); break;
1042 case T_DOUBLE: load = new LoadDNode (ctl, mem, adr, adr_type, rt, mo, control_dependency, require_atomic_access); break;
1043 case T_ADDRESS: load = new LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency); break;
1044 case T_OBJECT:
1045 case T_NARROWOOP:
1046 #ifdef _LP64
1047 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
1048 load = new LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo, control_dependency);
1049 } else
1050 #endif
1051 {
1052 assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop");
1053 load = new LoadPNode(ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency);
1054 }
1055 break;
1056 default:
1057 ShouldNotReachHere();
1058 break;
1059 }
1060 assert(load != nullptr, "LoadNode should have been created");
1061 if (unaligned) {
1062 load->set_unaligned_access();
1063 }
1064 if (mismatched) {
1065 load->set_mismatched_access();
1066 }
1067 if (unsafe) {
1068 load->set_unsafe_access();
1069 }
1070 load->set_barrier_data(barrier_data);
1071 if (load->Opcode() == Op_LoadN) {
1072 Node* ld = gvn.transform(load);
1073 return new DecodeNNode(ld, ld->bottom_type()->make_ptr());
1074 }
1075
1076 return load;
1077 }
1078
1079 //------------------------------hash-------------------------------------------
1080 uint LoadNode::hash() const {
1081 // unroll addition of interesting fields
1082 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
1083 }
1084
1085 static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) {
1086 if ((atp != nullptr) && (atp->index() >= Compile::AliasIdxRaw)) {
1087 bool non_volatile = (atp->field() != nullptr) && !atp->field()->is_volatile();
1088 bool is_stable_ary = FoldStableValues &&
1089 (tp != nullptr) && (tp->isa_aryptr() != nullptr) &&
1090 tp->isa_aryptr()->is_stable();
1091
1092 return (eliminate_boxing && non_volatile) || is_stable_ary;
1093 }
1094
1095 return false;
1096 }
1097
1098 // Is the value loaded previously stored by an arraycopy? If so return
1099 // a load node that reads from the source array so we may be able to
1100 // optimize out the ArrayCopy node later.
1101 Node* LoadNode::can_see_arraycopy_value(Node* st, PhaseGVN* phase) const {
1102 Node* ld_adr = in(MemNode::Address);
1103 intptr_t ld_off = 0;
1104 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
1105 Node* ac = find_previous_arraycopy(phase, ld_alloc, st, true);
1106 if (ac != nullptr) {
1107 assert(ac->is_ArrayCopy(), "what kind of node can this be?");
1108
1109 Node* mem = ac->in(TypeFunc::Memory);
1110 Node* ctl = ac->in(0);
1111 Node* src = ac->in(ArrayCopyNode::Src);
1112
1113 if (!ac->as_ArrayCopy()->is_clonebasic() && !phase->type(src)->isa_aryptr()) {
1114 return nullptr;
1115 }
1116
1117 // load depends on the tests that validate the arraycopy
1118 LoadNode* ld = clone_pinned();
1119 Node* addp = in(MemNode::Address)->clone();
1120 if (ac->as_ArrayCopy()->is_clonebasic()) {
1121 assert(ld_alloc != nullptr, "need an alloc");
1122 assert(addp->is_AddP(), "address must be addp");
1123 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1124 assert(bs->step_over_gc_barrier(addp->in(AddPNode::Base)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)), "strange pattern");
1125 assert(bs->step_over_gc_barrier(addp->in(AddPNode::Address)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)), "strange pattern");
1126 addp->set_req(AddPNode::Base, src);
1127 addp->set_req(AddPNode::Address, src);
1128 } else {
1129 assert(ac->as_ArrayCopy()->is_arraycopy_validated() ||
1130 ac->as_ArrayCopy()->is_copyof_validated() ||
1131 ac->as_ArrayCopy()->is_copyofrange_validated(), "only supported cases");
1132 assert(addp->in(AddPNode::Base) == addp->in(AddPNode::Address), "should be");
1133 addp->set_req(AddPNode::Base, src);
1134 addp->set_req(AddPNode::Address, src);
1135
1136 const TypeAryPtr* ary_t = phase->type(in(MemNode::Address))->isa_aryptr();
1137 BasicType ary_elem = ary_t->isa_aryptr()->elem()->array_element_basic_type();
1138 if (is_reference_type(ary_elem, true)) ary_elem = T_OBJECT;
1139
1140 uint header = arrayOopDesc::base_offset_in_bytes(ary_elem);
1141 uint shift = exact_log2(type2aelembytes(ary_elem));
1142
1143 Node* diff = phase->transform(new SubINode(ac->in(ArrayCopyNode::SrcPos), ac->in(ArrayCopyNode::DestPos)));
1144 #ifdef _LP64
1145 diff = phase->transform(new ConvI2LNode(diff));
1146 #endif
1147 diff = phase->transform(new LShiftXNode(diff, phase->intcon(shift)));
1148
1149 Node* offset = phase->transform(new AddXNode(addp->in(AddPNode::Offset), diff));
1150 addp->set_req(AddPNode::Offset, offset);
1151 }
1152 addp = phase->transform(addp);
1153 #ifdef ASSERT
1154 const TypePtr* adr_type = phase->type(addp)->is_ptr();
1155 ld->_adr_type = adr_type;
1156 #endif
1157 ld->set_req(MemNode::Address, addp);
1158 ld->set_req(0, ctl);
1159 ld->set_req(MemNode::Memory, mem);
1160 return ld;
1161 }
1162 return nullptr;
1163 }
1164
1165 // This routine exists to make sure this set of tests is done the same
1166 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
1167 // will change the graph shape in a way which makes memory alive twice at the
1168 // same time (uses the Oracle model of aliasing), then some
1169 // LoadXNode::Identity will fold things back to the equivalence-class model
1170 // of aliasing.
1171 Node* LoadNode::can_see_stored_value_through_membars(Node* st, PhaseValues* phase) const {
1172 Node* ld_adr = in(MemNode::Address);
1173 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
1174 Compile::AliasType* atp = (tp != nullptr) ? phase->C->alias_type(tp) : nullptr;
1175
1176 if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) {
1177 uint alias_idx = atp->index();
1178 Node* result = nullptr;
1179 Node* current = st;
1180 // Skip through chains of MemBarNodes checking the MergeMems for new states for the slice of
1181 // this load. Stop once any other kind of node is encountered.
1182 //
1183 // In principle, folding a load is moving it up until it meets a matching store.
1184 //
1185 // store(ptr, v); store(ptr, v); store(ptr, v);
1186 // membar1; -> membar1; -> load(ptr);
1187 // membar2; load(ptr); membar1;
1188 // load(ptr); membar2; membar2;
1189 //
1190 // So, we can decide which kinds of barriers we can walk past. It is not safe to step over
1191 // MemBarCPUOrder, even if the memory is not rewritable, because alias info above them may be
1192 // inaccurate (e.g., due to mixed/mismatched unsafe accesses).
1193 bool is_final_mem = !atp->is_rewritable();
1194 while (current->is_Proj()) {
1195 int opc = current->in(0)->Opcode();
1196 if ((is_final_mem && (opc == Op_MemBarAcquire || opc == Op_MemBarAcquireLock || opc == Op_LoadFence)) ||
1197 opc == Op_MemBarRelease ||
1198 opc == Op_StoreFence ||
1199 opc == Op_MemBarReleaseLock ||
1200 opc == Op_MemBarStoreStore ||
1201 opc == Op_StoreStoreFence) {
1202 Node* mem = current->in(0)->in(TypeFunc::Memory);
1203 if (mem->is_MergeMem()) {
1204 MergeMemNode* merge = mem->as_MergeMem();
1205 Node* new_st = merge->memory_at(alias_idx);
1206 if (new_st == merge->base_memory()) {
1207 // Keep searching
1208 current = new_st;
1209 continue;
1210 }
1211 // Save the new memory state for the slice and fall through
1212 // to exit.
1213 result = new_st;
1214 }
1215 }
1216 break;
1217 }
1218 if (result != nullptr) {
1219 st = result;
1220 }
1221 }
1222
1223 Node* res = can_see_stored_value(st, phase);
1224 assert(res == nullptr || is_java_primitive(value_basic_type()) || res->bottom_type()->higher_equal(type()), "the fold is unsafe");
1225 return res;
1226 }
1227
1228 // If st is a store to the same location as this, return the stored value
1229 Node* MemNode::can_see_stored_value(Node* st, PhaseValues* phase) const {
1230 Node* ld_adr = in(MemNode::Address);
1231 intptr_t ld_off = 0;
1232 Node* ld_base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ld_off);
1233 Node* ld_alloc = AllocateNode::Ideal_allocation(ld_base);
1234 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
1235
1236 // Loop around twice in the case Load -> Initialize -> Store.
1237 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
1238 for (int trip = 0; trip <= 1; trip++) {
1239
1240 if (st->is_Store()) {
1241 Node* st_adr = st->in(MemNode::Address);
1242 if (st_adr != ld_adr) {
1243 // Try harder before giving up. Unify base pointers with casts (e.g., raw/non-raw pointers).
1244 intptr_t st_off = 0;
1245 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_off);
1246 if (ld_base == nullptr) return nullptr;
1247 if (st_base == nullptr) return nullptr;
1248 if (!ld_base->eqv_uncast(st_base, /*keep_deps=*/true)) return nullptr;
1249 if (ld_off != st_off) return nullptr;
1250 if (ld_off == Type::OffsetBot) return nullptr;
1251 // Same base, same offset.
1252 // Possible improvement for arrays: check index value instead of absolute offset.
1253
1254 // At this point we have proven something like this setup:
1255 // B = << base >>
1256 // L = LoadQ(AddP(Check/CastPP(B), #Off))
1257 // S = StoreQ(AddP( B , #Off), V)
1258 // (Actually, we haven't yet proven the Q's are the same.)
1259 // In other words, we are loading from a casted version of
1260 // the same pointer-and-offset that we stored to.
1261 // Casted version may carry a dependency and it is respected.
1262 // Thus, we are able to replace L by V.
1263 }
1264 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
1265 if (store_Opcode() != st->Opcode()) {
1266 return nullptr;
1267 }
1268 // LoadVector/StoreVector needs additional check to ensure the types match.
1269 if (st->is_StoreVector()) {
1270 if ((Opcode() != Op_LoadVector && Opcode() != Op_StoreVector) || st->Opcode() != Op_StoreVector) {
1271 // Some kind of masked access or gather/scatter
1272 return nullptr;
1273 }
1274
1275 const TypeVect* in_vt = st->as_StoreVector()->vect_type();
1276 const TypeVect* out_vt = is_Load() ? as_LoadVector()->vect_type() : as_StoreVector()->vect_type();
1277 if (in_vt != out_vt) {
1278 return nullptr;
1279 }
1280 }
1281
1282 // Even if we can see the store, we cannot fold the load if the store is not type safe (e.g.
1283 // store a j.l.Object into an array of j.l.String) because folding makes the compiler lose the
1284 // type information that the uses of this node may need. This is only necessary for pointers, we
1285 // can see the stored value of a LoadS even if it is an int because LoadSNode::Ideal will do the
1286 // necessary truncation.
1287 // The same phenomenon is not an issue for StoreNodes because they don't use res.
1288 Node* res = st->in(MemNode::ValueIn);
1289 if (is_Store() || is_java_primitive(value_basic_type()) || res->bottom_type()->higher_equal(bottom_type())) {
1290 return res;
1291 }
1292
1293 // There are some cases in which the Type of the load is narrower than the Type of the value
1294 // that is stored into that location. The most common case is array polymorphism, when the
1295 // type of an array element depends on the type of the array. In addition, there are some
1296 // corner cases, the first one is concurrent class loading, when CHA can result in a narrower
1297 // Type than what is declared only after the child class is loaded, and the second case is
1298 // unsafe accesses when we do not check for type safety. See JDK-8388184.
1299 return nullptr;
1300 }
1301
1302 // A load from a freshly-created object always returns zero.
1303 // (This can happen after LoadNode::Ideal resets the load's memory input
1304 // to find_captured_store, which returned InitializeNode::zero_memory.)
1305 if (st->is_Proj() && st->in(0)->is_Allocate() &&
1306 (st->in(0) == ld_alloc) &&
1307 (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) {
1308 // return a zero value for the load's basic type
1309 // (This is one of the few places where a generic PhaseTransform
1310 // can create new nodes. Think of it as lazily manifesting
1311 // virtually pre-existing constants.)
1312 if (value_basic_type() != T_VOID) {
1313 if (ReduceBulkZeroing || find_array_copy_clone(ld_alloc, in(MemNode::Memory)) == nullptr) {
1314 // If ReduceBulkZeroing is disabled, we need to check if the allocation does not belong to an
1315 // ArrayCopyNode clone. If it does, then we cannot assume zero since the initialization is done
1316 // by the ArrayCopyNode.
1317 return phase->zerocon(value_basic_type());
1318 }
1319 } else {
1320 // TODO: materialize all-zero vector constant
1321 assert(!isa_Load() || as_Load()->type()->isa_vect(), "");
1322 }
1323 }
1324
1325 // A load from an initialization barrier can match a captured store.
1326 if (st->is_Proj() && st->in(0)->is_Initialize()) {
1327 InitializeNode* init = st->in(0)->as_Initialize();
1328 AllocateNode* alloc = init->allocation();
1329 if ((alloc != nullptr) && (alloc == ld_alloc)) {
1330 // examine a captured store value
1331 st = init->find_captured_store(ld_off, memory_size(), phase);
1332 if (st != nullptr) {
1333 continue; // take one more trip around
1334 }
1335 }
1336 }
1337
1338 // Load boxed value from result of valueOf() call is input parameter.
1339 if (this->is_Load() && ld_adr->is_AddP() &&
1340 (tp != nullptr) && tp->is_ptr_to_boxed_value()) {
1341 intptr_t ignore = 0;
1342 Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore);
1343 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1344 base = bs->step_over_gc_barrier(base);
1345 if (base != nullptr && base->is_Proj() &&
1346 base->as_Proj()->_con == TypeFunc::Parms &&
1347 base->in(0)->is_CallStaticJava() &&
1348 base->in(0)->as_CallStaticJava()->is_boxing_method()) {
1349 return base->in(0)->in(TypeFunc::Parms);
1350 }
1351 }
1352
1353 break;
1354 }
1355
1356 return nullptr;
1357 }
1358
1359 //----------------------is_instance_field_load_with_local_phi------------------
1360 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
1361 if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl &&
1362 in(Address)->is_AddP() ) {
1363 const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr();
1364 // Only instances and boxed values.
1365 if( t_oop != nullptr &&
1366 (t_oop->is_ptr_to_boxed_value() ||
1367 t_oop->is_known_instance_field()) &&
1368 t_oop->offset() != Type::OffsetBot &&
1369 t_oop->offset() != Type::OffsetTop) {
1370 return true;
1371 }
1372 }
1373 return false;
1374 }
1375
1376 //------------------------------Identity---------------------------------------
1377 // Loads are identity if previous store is to same address
1378 Node* LoadNode::Identity(PhaseGVN* phase) {
1379 // If the previous store-maker is the right kind of Store, and the store is
1380 // to the same address, then we are equal to the value stored.
1381 Node* mem = in(Memory);
1382 Node* value = can_see_stored_value_through_membars(mem, phase);
1383 if( value ) {
1384 // byte, short & char stores truncate naturally.
1385 // A load has to load the truncated value which requires
1386 // some sort of masking operation and that requires an
1387 // Ideal call instead of an Identity call.
1388 if (memory_size() < BytesPerInt) {
1389 // If the input to the store does not fit with the load's result type,
1390 // it must be truncated via an Ideal call.
1391 if (!phase->type(value)->higher_equal(phase->type(this)))
1392 return this;
1393 }
1394 // (This works even when value is a Con, but LoadNode::Value
1395 // usually runs first, producing the singleton type of the Con.)
1396 if (!has_pinned_control_dependency() || value->is_Con()) {
1397 return value;
1398 } else {
1399 return this;
1400 }
1401 }
1402
1403 if (has_pinned_control_dependency()) {
1404 return this;
1405 }
1406 // Search for an existing data phi which was generated before for the same
1407 // instance's field to avoid infinite generation of phis in a loop.
1408 Node *region = mem->in(0);
1409 if (is_instance_field_load_with_local_phi(region)) {
1410 const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr();
1411 int this_index = phase->C->get_alias_index(addr_t);
1412 int this_offset = addr_t->offset();
1413 int this_iid = addr_t->instance_id();
1414 if (!addr_t->is_known_instance() &&
1415 addr_t->is_ptr_to_boxed_value()) {
1416 // Use _idx of address base (could be Phi node) for boxed values.
1417 intptr_t ignore = 0;
1418 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1419 if (base == nullptr) {
1420 return this;
1421 }
1422 this_iid = base->_idx;
1423 }
1424 const Type* this_type = bottom_type();
1425 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1426 Node* phi = region->fast_out(i);
1427 if (phi->is_Phi() && phi != mem &&
1428 phi->as_Phi()->is_same_inst_field(this_type, (int)mem->_idx, this_iid, this_index, this_offset)) {
1429 return phi;
1430 }
1431 }
1432 }
1433
1434 return this;
1435 }
1436
1437 // Construct an equivalent unsigned load.
1438 Node* LoadNode::convert_to_unsigned_load(PhaseGVN& gvn) {
1439 BasicType bt = T_ILLEGAL;
1440 const Type* rt = nullptr;
1441 switch (Opcode()) {
1442 case Op_LoadUB: return this;
1443 case Op_LoadUS: return this;
1444 case Op_LoadB: bt = T_BOOLEAN; rt = TypeInt::UBYTE; break;
1445 case Op_LoadS: bt = T_CHAR; rt = TypeInt::CHAR; break;
1446 default:
1447 assert(false, "no unsigned variant: %s", Name());
1448 return nullptr;
1449 }
1450 const Type* mem_t = gvn.type(in(MemNode::Address));
1451 if (mem_t == Type::TOP) {
1452 return gvn.C->top();
1453 }
1454 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1455 mem_t->is_ptr(), rt, bt, _mo, _control_dependency,
1456 false /*require_atomic_access*/, is_unaligned_access(), is_mismatched_access());
1457 }
1458
1459 // Construct an equivalent signed load.
1460 Node* LoadNode::convert_to_signed_load(PhaseGVN& gvn) {
1461 BasicType bt = T_ILLEGAL;
1462 const Type* rt = nullptr;
1463 switch (Opcode()) {
1464 case Op_LoadUB: bt = T_BYTE; rt = TypeInt::BYTE; break;
1465 case Op_LoadUS: bt = T_SHORT; rt = TypeInt::SHORT; break;
1466 case Op_LoadB: // fall through
1467 case Op_LoadS: // fall through
1468 case Op_LoadI: // fall through
1469 case Op_LoadL: return this;
1470 default:
1471 assert(false, "no signed variant: %s", Name());
1472 return nullptr;
1473 }
1474 const Type* mem_t = gvn.type(in(MemNode::Address));
1475 if (mem_t == Type::TOP) {
1476 return gvn.C->top();
1477 }
1478 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1479 mem_t->is_ptr(), rt, bt, _mo, _control_dependency,
1480 false /*require_atomic_access*/, is_unaligned_access(), is_mismatched_access());
1481 }
1482
1483 bool LoadNode::has_reinterpret_variant(const Type* rt) {
1484 BasicType bt = rt->basic_type();
1485 switch (Opcode()) {
1486 case Op_LoadI: return (bt == T_FLOAT);
1487 case Op_LoadL: return (bt == T_DOUBLE);
1488 case Op_LoadF: return (bt == T_INT);
1489 case Op_LoadD: return (bt == T_LONG);
1490
1491 default: return false;
1492 }
1493 }
1494
1495 Node* LoadNode::convert_to_reinterpret_load(PhaseGVN& gvn, const Type* rt) {
1496 BasicType bt = rt->basic_type();
1497 assert(has_reinterpret_variant(rt), "no reinterpret variant: %s %s", Name(), type2name(bt));
1498 bool is_mismatched = is_mismatched_access();
1499 const TypeRawPtr* raw_type = gvn.type(in(MemNode::Memory))->isa_rawptr();
1500 if (raw_type == nullptr) {
1501 is_mismatched = true; // conservatively match all non-raw accesses as mismatched
1502 }
1503 const int op = Opcode();
1504 bool require_atomic_access = (op == Op_LoadL && ((LoadLNode*)this)->require_atomic_access()) ||
1505 (op == Op_LoadD && ((LoadDNode*)this)->require_atomic_access());
1506 const Type* mem_t = gvn.type(in(MemNode::Address));
1507 if (mem_t == Type::TOP) {
1508 return gvn.C->top();
1509 }
1510 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1511 mem_t->is_ptr(), rt, bt, _mo, _control_dependency,
1512 require_atomic_access, is_unaligned_access(), is_mismatched);
1513 }
1514
1515 bool StoreNode::has_reinterpret_variant(const Type* vt) {
1516 BasicType bt = vt->basic_type();
1517 switch (Opcode()) {
1518 case Op_StoreI: return (bt == T_FLOAT);
1519 case Op_StoreL: return (bt == T_DOUBLE);
1520 case Op_StoreF: return (bt == T_INT);
1521 case Op_StoreD: return (bt == T_LONG);
1522
1523 default: return false;
1524 }
1525 }
1526
1527 Node* StoreNode::convert_to_reinterpret_store(PhaseGVN& gvn, Node* val, const Type* vt) {
1528 BasicType bt = vt->basic_type();
1529 assert(has_reinterpret_variant(vt), "no reinterpret variant: %s %s", Name(), type2name(bt));
1530 const int op = Opcode();
1531 bool require_atomic_access = (op == Op_StoreL && ((StoreLNode*)this)->require_atomic_access()) ||
1532 (op == Op_StoreD && ((StoreDNode*)this)->require_atomic_access());
1533 const Type* mem_t = gvn.type(in(MemNode::Address));
1534 if (mem_t == Type::TOP) {
1535 return gvn.C->top();
1536 }
1537 StoreNode* st = StoreNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1538 mem_t->is_ptr(), val, bt, _mo, require_atomic_access);
1539
1540 bool is_mismatched = is_mismatched_access();
1541 const TypeRawPtr* raw_type = gvn.type(in(MemNode::Memory))->isa_rawptr();
1542 if (raw_type == nullptr) {
1543 is_mismatched = true; // conservatively match all non-raw accesses as mismatched
1544 }
1545 if (is_mismatched) {
1546 st->set_mismatched_access();
1547 }
1548 return st;
1549 }
1550
1551 // We're loading from an object which has autobox behaviour.
1552 // If this object is result of a valueOf call we'll have a phi
1553 // merging a newly allocated object and a load from the cache.
1554 // We want to replace this load with the original incoming
1555 // argument to the valueOf call.
1556 Node* LoadNode::eliminate_autobox(PhaseIterGVN* igvn) {
1557 assert(igvn->C->eliminate_boxing(), "sanity");
1558 intptr_t ignore = 0;
1559 Node* base = AddPNode::Ideal_base_and_offset(in(Address), igvn, ignore);
1560 if ((base == nullptr) || base->is_Phi()) {
1561 // Push the loads from the phi that comes from valueOf up
1562 // through it to allow elimination of the loads and the recovery
1563 // of the original value. It is done in split_through_phi().
1564 return nullptr;
1565 } else if (base->is_Load() ||
1566 (base->is_DecodeN() && base->in(1)->is_Load())) {
1567 // Eliminate the load of boxed value for integer types from the cache
1568 // array by deriving the value from the index into the array.
1569 // Capture the offset of the load and then reverse the computation.
1570
1571 // Get LoadN node which loads a boxing object from 'cache' array.
1572 if (base->is_DecodeN()) {
1573 base = base->in(1);
1574 }
1575 if (!base->in(Address)->is_AddP()) {
1576 return nullptr; // Complex address
1577 }
1578 AddPNode* address = base->in(Address)->as_AddP();
1579 Node* cache_base = address->in(AddPNode::Base);
1580 if ((cache_base != nullptr) && cache_base->is_DecodeN()) {
1581 // Get ConP node which is static 'cache' field.
1582 cache_base = cache_base->in(1);
1583 }
1584 if ((cache_base != nullptr) && cache_base->is_Con()) {
1585 const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr();
1586 if ((base_type != nullptr) && base_type->is_autobox_cache()) {
1587 Node* elements[4];
1588 int shift = exact_log2(type2aelembytes(T_OBJECT));
1589 int count = address->unpack_offsets(elements, ARRAY_SIZE(elements));
1590 if (count > 0 && elements[0]->is_Con() &&
1591 (count == 1 ||
1592 (count == 2 && elements[1]->Opcode() == Op_LShiftX &&
1593 elements[1]->in(2) == igvn->intcon(shift)))) {
1594 ciObjArray* array = base_type->const_oop()->as_obj_array();
1595 // Fetch the box object cache[0] at the base of the array and get its value
1596 ciInstance* box = array->obj_at(0)->as_instance();
1597 ciInstanceKlass* ik = box->klass()->as_instance_klass();
1598 assert(ik->is_box_klass(), "sanity");
1599 assert(ik->nof_nonstatic_fields() == 1, "change following code");
1600 if (ik->nof_nonstatic_fields() == 1) {
1601 // This should be true nonstatic_field_at requires calling
1602 // nof_nonstatic_fields so check it anyway
1603 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1604 BasicType bt = c.basic_type();
1605 // Only integer types have boxing cache.
1606 assert(bt == T_BOOLEAN || bt == T_CHAR ||
1607 bt == T_BYTE || bt == T_SHORT ||
1608 bt == T_INT || bt == T_LONG, "wrong type = %s", type2name(bt));
1609 jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int();
1610 if (cache_low != (int)cache_low) {
1611 return nullptr; // should not happen since cache is array indexed by value
1612 }
1613 jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift);
1614 if (offset != (int)offset) {
1615 return nullptr; // should not happen since cache is array indexed by value
1616 }
1617 // Add up all the offsets making of the address of the load
1618 Node* result = elements[0];
1619 for (int i = 1; i < count; i++) {
1620 result = igvn->transform(new AddXNode(result, elements[i]));
1621 }
1622 // Remove the constant offset from the address and then
1623 result = igvn->transform(new AddXNode(result, igvn->MakeConX(-(int)offset)));
1624 // remove the scaling of the offset to recover the original index.
1625 if (result->Opcode() == Op_LShiftX && result->in(2) == igvn->intcon(shift)) {
1626 // Peel the shift off directly but wrap it in a dummy node
1627 // since Ideal can't return existing nodes
1628 igvn->_worklist.push(result); // remove dead node later
1629 result = new RShiftXNode(result->in(1), igvn->intcon(0));
1630 } else if (result->is_Add() && result->in(2)->is_Con() &&
1631 result->in(1)->Opcode() == Op_LShiftX &&
1632 result->in(1)->in(2) == igvn->intcon(shift)) {
1633 // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z)
1634 // but for boxing cache access we know that X<<Z will not overflow
1635 // (there is range check) so we do this optimizatrion by hand here.
1636 igvn->_worklist.push(result); // remove dead node later
1637 Node* add_con = new RShiftXNode(result->in(2), igvn->intcon(shift));
1638 result = new AddXNode(result->in(1)->in(1), igvn->transform(add_con));
1639 } else {
1640 result = new RShiftXNode(result, igvn->intcon(shift));
1641 }
1642 #ifdef _LP64
1643 if (bt != T_LONG) {
1644 result = new ConvL2INode(igvn->transform(result));
1645 }
1646 #else
1647 if (bt == T_LONG) {
1648 result = new ConvI2LNode(igvn->transform(result));
1649 }
1650 #endif
1651 // Boxing/unboxing can be done from signed & unsigned loads (e.g. LoadUB -> ... -> LoadB pair).
1652 // Need to preserve unboxing load type if it is unsigned.
1653 switch(this->Opcode()) {
1654 case Op_LoadUB:
1655 result = new AndINode(igvn->transform(result), igvn->intcon(0xFF));
1656 break;
1657 case Op_LoadUS:
1658 result = new AndINode(igvn->transform(result), igvn->intcon(0xFFFF));
1659 break;
1660 }
1661 return result;
1662 }
1663 }
1664 }
1665 }
1666 }
1667 return nullptr;
1668 }
1669
1670 static bool stable_phi(PhiNode* phi, PhaseGVN *phase) {
1671 Node* region = phi->in(0);
1672 if (region == nullptr) {
1673 return false; // Wait stable graph
1674 }
1675 uint cnt = phi->req();
1676 for (uint i = 1; i < cnt; i++) {
1677 Node* rc = region->in(i);
1678 if (rc == nullptr || phase->type(rc) == Type::TOP)
1679 return false; // Wait stable graph
1680 Node* in = phi->in(i);
1681 if (in == nullptr || phase->type(in) == Type::TOP)
1682 return false; // Wait stable graph
1683 }
1684 return true;
1685 }
1686
1687 //------------------------------split_through_phi------------------------------
1688 // Check whether a call to 'split_through_phi' would split this load through the
1689 // Phi *base*. This method is essentially a copy of the validations performed
1690 // by 'split_through_phi'. The first use of this method was in EA code as part
1691 // of simplification of allocation merges.
1692 // Some differences from original method (split_through_phi):
1693 // - If base->is_CastPP(): base = base->in(1)
1694 bool LoadNode::can_split_through_phi_base(PhaseGVN* phase) {
1695 Node* mem = in(Memory);
1696 Node* address = in(Address);
1697 intptr_t ignore = 0;
1698 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1699
1700 if (base == nullptr) {
1701 return false;
1702 }
1703
1704 if (base->is_CastPP()) {
1705 base = base->in(1);
1706 }
1707
1708 if (req() > 3 || !base->is_Phi()) {
1709 return false;
1710 }
1711
1712 if (!mem->is_Phi()) {
1713 if (!MemNode::all_controls_dominate(mem, base->in(0), phase)) {
1714 return false;
1715 }
1716 } else if (base->in(0) != mem->in(0)) {
1717 if (!MemNode::all_controls_dominate(mem, base->in(0), phase)) {
1718 return false;
1719 }
1720 }
1721
1722 return true;
1723 }
1724
1725 //------------------------------split_through_phi------------------------------
1726 // Split instance or boxed field load through Phi.
1727 Node* LoadNode::split_through_phi(PhaseGVN* phase, bool ignore_missing_instance_id) {
1728 if (req() > 3) {
1729 assert(is_LoadVector() && Opcode() != Op_LoadVector, "load has too many inputs");
1730 // LoadVector subclasses such as LoadVectorMasked have extra inputs that the logic below doesn't take into account
1731 return nullptr;
1732 }
1733 Node* mem = in(Memory);
1734 Node* address = in(Address);
1735 const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr();
1736
1737 assert((t_oop != nullptr) &&
1738 (ignore_missing_instance_id ||
1739 t_oop->is_known_instance_field() ||
1740 t_oop->is_ptr_to_boxed_value()), "invalid conditions");
1741
1742 Compile* C = phase->C;
1743 intptr_t ignore = 0;
1744 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1745 bool base_is_phi = (base != nullptr) && base->is_Phi();
1746 bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() &&
1747 (base != nullptr) && (base == address->in(AddPNode::Base)) &&
1748 phase->type(base)->higher_equal(TypePtr::NOTNULL);
1749
1750 if (!((mem->is_Phi() || base_is_phi) &&
1751 (ignore_missing_instance_id || load_boxed_values || t_oop->is_known_instance_field()))) {
1752 return nullptr; // Neither memory or base are Phi
1753 }
1754
1755 if (mem->is_Phi()) {
1756 if (!stable_phi(mem->as_Phi(), phase)) {
1757 return nullptr; // Wait stable graph
1758 }
1759 uint cnt = mem->req();
1760 // Check for loop invariant memory.
1761 if (cnt == 3) {
1762 for (uint i = 1; i < cnt; i++) {
1763 Node* in = mem->in(i);
1764 Node* m = optimize_memory_chain(in, t_oop, this, phase);
1765 if (m == mem) {
1766 if (i == 1) {
1767 // if the first edge was a loop, check second edge too.
1768 // If both are replaceable - we are in an infinite loop
1769 Node *n = optimize_memory_chain(mem->in(2), t_oop, this, phase);
1770 if (n == mem) {
1771 break;
1772 }
1773 }
1774 set_req(Memory, mem->in(cnt - i));
1775 return this; // made change
1776 }
1777 }
1778 }
1779 }
1780 if (base_is_phi) {
1781 if (!stable_phi(base->as_Phi(), phase)) {
1782 return nullptr; // Wait stable graph
1783 }
1784 uint cnt = base->req();
1785 // Check for loop invariant memory.
1786 if (cnt == 3) {
1787 for (uint i = 1; i < cnt; i++) {
1788 if (base->in(i) == base) {
1789 return nullptr; // Wait stable graph
1790 }
1791 }
1792 }
1793 }
1794
1795 // Split through Phi (see original code in loopopts.cpp).
1796 assert(ignore_missing_instance_id || C->have_alias_type(t_oop), "instance should have alias type");
1797
1798 // Do nothing here if Identity will find a value
1799 // (to avoid infinite chain of value phis generation).
1800 if (this != Identity(phase)) {
1801 return nullptr;
1802 }
1803
1804 // Select Region to split through.
1805 Node* region;
1806 DomResult dom_result = DomResult::Dominate;
1807 if (!base_is_phi) {
1808 assert(mem->is_Phi(), "sanity");
1809 region = mem->in(0);
1810 // Skip if the region dominates some control edge of the address.
1811 // We will check `dom_result` later.
1812 dom_result = MemNode::maybe_all_controls_dominate(address, region, phase);
1813 } else if (!mem->is_Phi()) {
1814 assert(base_is_phi, "sanity");
1815 region = base->in(0);
1816 // Skip if the region dominates some control edge of the memory.
1817 // We will check `dom_result` later.
1818 dom_result = MemNode::maybe_all_controls_dominate(mem, region, phase);
1819 } else if (base->in(0) != mem->in(0)) {
1820 assert(base_is_phi && mem->is_Phi(), "sanity");
1821 dom_result = MemNode::maybe_all_controls_dominate(mem, base->in(0), phase);
1822 if (dom_result == DomResult::Dominate) {
1823 region = base->in(0);
1824 } else {
1825 dom_result = MemNode::maybe_all_controls_dominate(address, mem->in(0), phase);
1826 if (dom_result == DomResult::Dominate) {
1827 region = mem->in(0);
1828 }
1829 // Otherwise we encountered a complex graph.
1830 }
1831 } else {
1832 assert(base->in(0) == mem->in(0), "sanity");
1833 region = mem->in(0);
1834 }
1835
1836 PhaseIterGVN* igvn = phase->is_IterGVN();
1837 if (dom_result != DomResult::Dominate) {
1838 if (dom_result == DomResult::EncounteredDeadCode) {
1839 // There is some dead code which eventually will be removed in IGVN.
1840 // Once this is the case, we get an unambiguous dominance result.
1841 // Push the node to the worklist again until the dead code is removed.
1842 igvn->_worklist.push(this);
1843 }
1844 return nullptr;
1845 }
1846
1847 Node* phi = nullptr;
1848 const Type* this_type = this->bottom_type();
1849 if (t_oop != nullptr && (t_oop->is_known_instance_field() || load_boxed_values)) {
1850 int this_index = C->get_alias_index(t_oop);
1851 int this_offset = t_oop->offset();
1852 int this_iid = t_oop->is_known_instance_field() ? t_oop->instance_id() : base->_idx;
1853 phi = new PhiNode(region, this_type, nullptr, mem->_idx, this_iid, this_index, this_offset);
1854 } else if (ignore_missing_instance_id) {
1855 phi = new PhiNode(region, this_type, nullptr, mem->_idx);
1856 } else {
1857 return nullptr;
1858 }
1859
1860 for (uint i = 1; i < region->req(); i++) {
1861 Node* x;
1862 Node* the_clone = nullptr;
1863 Node* in = region->in(i);
1864 if (region->is_CountedLoop() && region->as_Loop()->is_strip_mined() && i == LoopNode::EntryControl &&
1865 in != nullptr && in->is_OuterStripMinedLoop()) {
1866 // No node should go in the outer strip mined loop
1867 in = in->in(LoopNode::EntryControl);
1868 }
1869 if (in == nullptr || in == C->top()) {
1870 x = C->top(); // Dead path? Use a dead data op
1871 } else {
1872 x = this->clone(); // Else clone up the data op
1873 the_clone = x; // Remember for possible deletion.
1874 // Alter data node to use pre-phi inputs
1875 if (this->in(0) == region) {
1876 x->set_req(0, in);
1877 } else {
1878 x->set_req(0, nullptr);
1879 }
1880 if (mem->is_Phi() && (mem->in(0) == region)) {
1881 x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone.
1882 }
1883 if (address->is_Phi() && address->in(0) == region) {
1884 x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone
1885 }
1886 if (base_is_phi && (base->in(0) == region)) {
1887 Node* base_x = base->in(i); // Clone address for loads from boxed objects.
1888 Node* adr_x = phase->transform(AddPNode::make_with_base(base_x, address->in(AddPNode::Offset)));
1889 x->set_req(Address, adr_x);
1890 }
1891 }
1892 // Check for a 'win' on some paths
1893 const Type *t = x->Value(igvn);
1894
1895 bool singleton = t->singleton();
1896
1897 // See comments in PhaseIdealLoop::split_thru_phi().
1898 if (singleton && t == Type::TOP) {
1899 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1900 }
1901
1902 if (singleton) {
1903 x = igvn->makecon(t);
1904 } else {
1905 // We now call Identity to try to simplify the cloned node.
1906 // Note that some Identity methods call phase->type(this).
1907 // Make sure that the type array is big enough for
1908 // our new node, even though we may throw the node away.
1909 // (This tweaking with igvn only works because x is a new node.)
1910 igvn->set_type(x, t);
1911 // If x is a TypeNode, capture any more-precise type permanently into Node
1912 // otherwise it will be not updated during igvn->transform since
1913 // igvn->type(x) is set to x->Value() already.
1914 x->raise_bottom_type(t);
1915 Node* y = x->Identity(igvn);
1916 if (y != x) {
1917 x = y;
1918 } else {
1919 y = igvn->hash_find_insert(x);
1920 if (y) {
1921 x = y;
1922 } else {
1923 // Else x is a new node we are keeping
1924 // We do not need register_new_node_with_optimizer
1925 // because set_type has already been called.
1926 igvn->_worklist.push(x);
1927 }
1928 }
1929 }
1930 if (x != the_clone && the_clone != nullptr) {
1931 igvn->remove_dead_node(the_clone, PhaseIterGVN::NodeOrigin::Speculative);
1932 }
1933 phi->set_req(i, x);
1934 }
1935 // Record Phi
1936 igvn->register_new_node_with_optimizer(phi);
1937 return phi;
1938 }
1939
1940 AllocateNode* LoadNode::is_new_object_mark_load() const {
1941 if (Opcode() == Op_LoadX) {
1942 Node* address = in(MemNode::Address);
1943 AllocateNode* alloc = AllocateNode::Ideal_allocation(address);
1944 Node* mem = in(MemNode::Memory);
1945 if (alloc != nullptr && mem->is_Proj() &&
1946 mem->in(0) != nullptr &&
1947 mem->in(0) == alloc->initialization() &&
1948 alloc->initialization()->proj_out_or_null(0) != nullptr) {
1949 return alloc;
1950 }
1951 }
1952 return nullptr;
1953 }
1954
1955
1956 //------------------------------Ideal------------------------------------------
1957 // If the load is from Field memory and the pointer is non-null, it might be possible to
1958 // zero out the control input.
1959 // If the offset is constant and the base is an object allocation,
1960 // try to hook me up to the exact initializing store.
1961 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1962 if (has_pinned_control_dependency()) {
1963 return nullptr;
1964 }
1965 Node* p = MemNode::Ideal_common(phase, can_reshape);
1966 if (p) return (p == NodeSentinel) ? nullptr : p;
1967
1968 Node* ctrl = in(MemNode::Control);
1969 Node* address = in(MemNode::Address);
1970
1971 bool addr_mark = ((phase->type(address)->isa_oopptr() || phase->type(address)->isa_narrowoop()) &&
1972 phase->type(address)->is_ptr()->offset() == oopDesc::mark_offset_in_bytes());
1973
1974 // Skip up past a SafePoint control. Cannot do this for Stores because
1975 // pointer stores & cardmarks must stay on the same side of a SafePoint.
1976 if( ctrl != nullptr && ctrl->Opcode() == Op_SafePoint &&
1977 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw &&
1978 !addr_mark &&
1979 (depends_only_on_test() || has_unknown_control_dependency())) {
1980 ctrl = ctrl->in(0);
1981 set_req(MemNode::Control,ctrl);
1982 return this;
1983 }
1984
1985 intptr_t ignore = 0;
1986 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1987 if (base != nullptr
1988 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
1989 // Check for useless control edge in some common special cases
1990 if (in(MemNode::Control) != nullptr
1991 && can_remove_control()
1992 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1993 && all_controls_dominate(base, phase->C->start(), phase)) {
1994 // A method-invariant, non-null address (constant or 'this' argument).
1995 set_req(MemNode::Control, nullptr);
1996 return this;
1997 }
1998 }
1999
2000 Node* mem = in(MemNode::Memory);
2001 const TypePtr *addr_t = phase->type(address)->isa_ptr();
2002
2003 if (can_reshape && (addr_t != nullptr)) {
2004 // try to optimize our memory input
2005 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase);
2006 if (opt_mem != mem) {
2007 set_req_X(MemNode::Memory, opt_mem, phase);
2008 if (phase->type( opt_mem ) == Type::TOP) return nullptr;
2009 return this;
2010 }
2011 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
2012 if ((t_oop != nullptr) &&
2013 (t_oop->is_known_instance_field() ||
2014 t_oop->is_ptr_to_boxed_value())) {
2015 PhaseIterGVN *igvn = phase->is_IterGVN();
2016 assert(igvn != nullptr, "must be PhaseIterGVN when can_reshape is true");
2017 if (igvn->_worklist.member(opt_mem)) {
2018 // Delay this transformation until memory Phi is processed.
2019 igvn->_worklist.push(this);
2020 return nullptr;
2021 }
2022 // Split instance field load through Phi.
2023 Node* result = split_through_phi(phase);
2024 if (result != nullptr) return result;
2025
2026 if (t_oop->is_ptr_to_boxed_value()) {
2027 Node* result = eliminate_autobox(igvn);
2028 if (result != nullptr) return result;
2029 }
2030 }
2031 }
2032
2033 // Is there a dominating load that loads the same value? Leave
2034 // anything that is not a load of a field/array element (like
2035 // barriers etc.) alone
2036 if (in(0) != nullptr && !adr_type()->isa_rawptr() && can_reshape) {
2037 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) {
2038 Node *use = mem->fast_out(i);
2039 if (use != this &&
2040 use->Opcode() == Opcode() &&
2041 use->in(0) != nullptr &&
2042 use->in(0) != in(0) &&
2043 use->in(Address) == in(Address)) {
2044 Node* ctl = in(0);
2045 for (int i = 0; i < 10 && ctl != nullptr; i++) {
2046 ctl = IfNode::up_one_dom(ctl);
2047 if (ctl == use->in(0)) {
2048 set_req(0, use->in(0));
2049 return this;
2050 }
2051 }
2052 }
2053 }
2054 }
2055
2056 // Check for prior store with a different base or offset; make Load
2057 // independent. Skip through any number of them. Bail out if the stores
2058 // are in an endless dead cycle and report no progress. This is a key
2059 // transform for Reflection. However, if after skipping through the Stores
2060 // we can't then fold up against a prior store do NOT do the transform as
2061 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
2062 // array memory alive twice: once for the hoisted Load and again after the
2063 // bypassed Store. This situation only works if EVERYBODY who does
2064 // anti-dependence work knows how to bypass. I.e. we need all
2065 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
2066 // the alias index stuff. So instead, peek through Stores and IFF we can
2067 // fold up, do so.
2068 Node* prev_mem = find_previous_store(phase);
2069 if (prev_mem != nullptr && prev_mem->is_top()) {
2070 // find_previous_store returns top when the access is dead
2071 return prev_mem;
2072 }
2073 if (prev_mem != nullptr) {
2074 Node* value = can_see_arraycopy_value(prev_mem, phase);
2075 if (value != nullptr) {
2076 return value;
2077 }
2078 }
2079 // Steps (a), (b): Walk past independent stores to find an exact match.
2080 if (prev_mem != nullptr && prev_mem != in(MemNode::Memory)) {
2081 // (c) See if we can fold up on the spot, but don't fold up here.
2082 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
2083 // just return a prior value, which is done by Identity calls.
2084 if (can_see_stored_value_through_membars(prev_mem, phase)) {
2085 // Make ready for step (d):
2086 set_req_X(MemNode::Memory, prev_mem, phase);
2087 return this;
2088 }
2089 }
2090
2091 if (!can_reshape) {
2092 phase->record_for_igvn(this);
2093 }
2094
2095 return nullptr;
2096 }
2097
2098 // Helper to recognize certain Klass fields which are invariant across
2099 // some group of array types (e.g., int[] or all T[] where T < Object).
2100 const Type*
2101 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
2102 ciKlass* klass) const {
2103 assert(!UseCompactObjectHeaders || tkls->offset() != in_bytes(Klass::prototype_header_offset()),
2104 "must not happen");
2105
2106 if (tkls->isa_instklassptr() && tkls->offset() == in_bytes(InstanceKlass::access_flags_offset())) {
2107 // The field is InstanceKlass::_access_flags. Return its (constant) value.
2108 assert(Opcode() == Op_LoadUS, "must load an unsigned short from _access_flags");
2109 ciInstanceKlass* iklass = tkls->is_instklassptr()->instance_klass();
2110 return TypeInt::make(iklass->access_flags());
2111 }
2112 if (tkls->offset() == in_bytes(Klass::misc_flags_offset())) {
2113 // The field is Klass::_misc_flags. Return its (constant) value.
2114 assert(Opcode() == Op_LoadUB, "must load an unsigned byte from _misc_flags");
2115 return TypeInt::make(klass->misc_flags());
2116 }
2117 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) {
2118 // The field is Klass::_layout_helper. Return its constant value if known.
2119 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
2120 return TypeInt::make(klass->layout_helper());
2121 }
2122
2123 // No match.
2124 return nullptr;
2125 }
2126
2127 //------------------------------Value-----------------------------------------
2128 const Type* LoadNode::Value(PhaseGVN* phase) const {
2129 // Either input is TOP ==> the result is TOP
2130 Node* mem = in(MemNode::Memory);
2131 const Type *t1 = phase->type(mem);
2132 if (t1 == Type::TOP) return Type::TOP;
2133 Node* adr = in(MemNode::Address);
2134 const TypePtr* tp = phase->type(adr)->isa_ptr();
2135 if (tp == nullptr || tp->empty()) return Type::TOP;
2136 int off = tp->offset();
2137 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
2138 Compile* C = phase->C;
2139
2140 // If load can see a previous constant store, use that.
2141 Node* value = can_see_stored_value_through_membars(mem, phase);
2142 if (value != nullptr && value->is_Con()) {
2143 assert(value->bottom_type()->higher_equal(_type), "sanity");
2144 return value->bottom_type();
2145 }
2146
2147 // Try to guess loaded type from pointer type
2148 if (tp->isa_aryptr()) {
2149 const TypeAryPtr* ary = tp->is_aryptr();
2150 const Type* t = ary->elem();
2151
2152 // Determine whether the reference is beyond the header or not, by comparing
2153 // the offset against the offset of the start of the array's data.
2154 // Different array types begin at slightly different offsets (12 vs. 16).
2155 // We choose T_BYTE as an example base type that is least restrictive
2156 // as to alignment, which will therefore produce the smallest
2157 // possible base offset.
2158 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
2159 const bool off_beyond_header = (off >= min_base_off);
2160
2161 // Try to constant-fold a stable array element.
2162 if (FoldStableValues && !is_mismatched_access() && ary->is_stable()) {
2163 // Make sure the reference is not into the header and the offset is constant
2164 ciObject* aobj = ary->const_oop();
2165 if (aobj != nullptr && off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) {
2166 int stable_dimension = (ary->stable_dimension() > 0 ? ary->stable_dimension() - 1 : 0);
2167 const Type* con_type = Type::make_constant_from_array_element(aobj->as_array(), off,
2168 stable_dimension,
2169 value_basic_type(), is_unsigned());
2170 if (con_type != nullptr) {
2171 return con_type;
2172 }
2173 }
2174 }
2175
2176 // Don't do this for integer types. There is only potential profit if
2177 // the element type t is lower than _type; that is, for int types, if _type is
2178 // more restrictive than t. This only happens here if one is short and the other
2179 // char (both 16 bits), and in those cases we've made an intentional decision
2180 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
2181 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
2182 //
2183 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
2184 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
2185 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
2186 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
2187 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
2188 // In fact, that could have been the original type of p1, and p1 could have
2189 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
2190 // expression (LShiftL quux 3) independently optimized to the constant 8.
2191 if ((t->isa_int() == nullptr) && (t->isa_long() == nullptr)
2192 && (_type->isa_vect() == nullptr)
2193 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
2194 // t might actually be lower than _type, if _type is a unique
2195 // concrete subclass of abstract class t.
2196 if (off_beyond_header || off == Type::OffsetBot) { // is the offset beyond the header?
2197 const Type* jt = t->join_speculative(_type);
2198 // In any case, do not allow the join, per se, to empty out the type.
2199 if (jt->empty() && !t->empty()) {
2200 // This can happen if a interface-typed array narrows to a class type.
2201 jt = _type;
2202 }
2203 #ifdef ASSERT
2204 if (phase->C->eliminate_boxing() && adr->is_AddP()) {
2205 // The pointers in the autobox arrays are always non-null
2206 Node* base = adr->in(AddPNode::Base);
2207 if ((base != nullptr) && base->is_DecodeN()) {
2208 // Get LoadN node which loads IntegerCache.cache field
2209 base = base->in(1);
2210 }
2211 if ((base != nullptr) && base->is_Con()) {
2212 const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr();
2213 if ((base_type != nullptr) && base_type->is_autobox_cache()) {
2214 // It could be narrow oop
2215 assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity");
2216 }
2217 }
2218 }
2219 #endif
2220 return jt;
2221 }
2222 }
2223 } else if (tp->base() == Type::InstPtr) {
2224 assert( off != Type::OffsetBot ||
2225 // arrays can be cast to Objects
2226 !tp->isa_instptr() ||
2227 tp->is_instptr()->instance_klass()->is_java_lang_Object() ||
2228 // unsafe field access may not have a constant offset
2229 C->has_unsafe_access(),
2230 "Field accesses must be precise" );
2231 // For oop loads, we expect the _type to be precise.
2232
2233 // Optimize loads from constant fields.
2234 const TypeInstPtr* tinst = tp->is_instptr();
2235 ciObject* const_oop = tinst->const_oop();
2236 if (!is_mismatched_access() && off != Type::OffsetBot && const_oop != nullptr && const_oop->is_instance()) {
2237 const Type* con_type = Type::make_constant_from_field(const_oop->as_instance(), off, is_unsigned(), value_basic_type());
2238 if (con_type != nullptr) {
2239 return con_type;
2240 }
2241 }
2242 } else if (tp->base() == Type::KlassPtr || tp->base() == Type::InstKlassPtr || tp->base() == Type::AryKlassPtr) {
2243 assert(off != Type::OffsetBot ||
2244 !tp->isa_instklassptr() ||
2245 // arrays can be cast to Objects
2246 tp->isa_instklassptr()->instance_klass()->is_java_lang_Object() ||
2247 // also allow array-loading from the primary supertype
2248 // array during subtype checks
2249 Opcode() == Op_LoadKlass,
2250 "Field accesses must be precise");
2251 // For klass/static loads, we expect the _type to be precise
2252 } else if (tp->base() == Type::RawPtr && adr->is_Load() && off == 0) {
2253 /* With mirrors being an indirect in the Klass*
2254 * the VM is now using two loads. LoadKlass(LoadP(LoadP(Klass, mirror_offset), zero_offset))
2255 * The LoadP from the Klass has a RawPtr type (see LibraryCallKit::load_mirror_from_klass).
2256 *
2257 * So check the type and klass of the node before the LoadP.
2258 */
2259 Node* adr2 = adr->in(MemNode::Address);
2260 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2261 if (tkls != nullptr && !StressReflectiveCode) {
2262 if (tkls->is_loaded() && tkls->klass_is_exact() && tkls->offset() == in_bytes(Klass::java_mirror_offset())) {
2263 ciKlass* klass = tkls->exact_klass();
2264 assert(adr->Opcode() == Op_LoadP, "must load an oop from _java_mirror");
2265 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
2266 return TypeInstPtr::make(klass->java_mirror());
2267 }
2268 }
2269 }
2270
2271 const TypeKlassPtr *tkls = tp->isa_klassptr();
2272 if (tkls != nullptr) {
2273 if (tkls->is_loaded() && tkls->klass_is_exact()) {
2274 ciKlass* klass = tkls->exact_klass();
2275 // We are loading a field from a Klass metaobject whose identity
2276 // is known at compile time (the type is "exact" or "precise").
2277 // Check for fields we know are maintained as constants by the VM.
2278 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) {
2279 // The field is Klass::_super_check_offset. Return its (constant) value.
2280 // (Folds up type checking code.)
2281 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
2282 return TypeInt::make(klass->super_check_offset());
2283 }
2284 if (UseCompactObjectHeaders) {
2285 if (tkls->offset() == in_bytes(Klass::prototype_header_offset())) {
2286 // The field is Klass::_prototype_header. Return its (constant) value.
2287 assert(this->Opcode() == Op_LoadX, "must load a proper type from _prototype_header");
2288 return TypeX::make(klass->prototype_header());
2289 }
2290 }
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 // The field is an element of Klass::_primary_supers. Return its (constant) value.
2296 // (Folds up type checking code.)
2297 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
2298 ciKlass *ss = klass->super_of_depth(depth);
2299 return ss ? TypeKlassPtr::make(ss, Type::trust_interfaces) : TypePtr::NULL_PTR;
2300 }
2301 const Type* aift = load_array_final_field(tkls, klass);
2302 if (aift != nullptr) return aift;
2303 }
2304
2305 // We can still check if we are loading from the primary_supers array at a
2306 // shallow enough depth. Even though the klass is not exact, entries less
2307 // than or equal to its super depth are correct.
2308 if (tkls->is_loaded()) {
2309 ciKlass* klass = nullptr;
2310 if (tkls->isa_instklassptr()) {
2311 klass = tkls->is_instklassptr()->instance_klass();
2312 } else {
2313 int dims;
2314 const Type* inner = tkls->is_aryklassptr()->base_element_type(dims);
2315 if (inner->isa_instklassptr()) {
2316 klass = inner->is_instklassptr()->instance_klass();
2317 klass = ciObjArrayKlass::make(klass, dims);
2318 }
2319 }
2320 if (klass != nullptr) {
2321 // Compute index into primary_supers array
2322 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
2323 // Check for overflowing; use unsigned compare to handle the negative case.
2324 if (depth < ciKlass::primary_super_limit() &&
2325 depth <= klass->super_depth()) { // allow self-depth checks to handle self-check case
2326 // The field is an element of Klass::_primary_supers. Return its (constant) value.
2327 // (Folds up type checking code.)
2328 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
2329 ciKlass *ss = klass->super_of_depth(depth);
2330 return ss ? TypeKlassPtr::make(ss, Type::trust_interfaces) : TypePtr::NULL_PTR;
2331 }
2332 }
2333 }
2334
2335 // If the type is enough to determine that the thing is not an array,
2336 // we can give the layout_helper a positive interval type.
2337 // This will help short-circuit some reflective code.
2338 if (tkls->offset() == in_bytes(Klass::layout_helper_offset()) &&
2339 tkls->isa_instklassptr() && // not directly typed as an array
2340 !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
2341 ) {
2342 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
2343 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
2344 // The key property of this type is that it folds up tests
2345 // for array-ness, since it proves that the layout_helper is positive.
2346 // Thus, a generic value like the basic object layout helper works fine.
2347 return TypeInt::make(min_size, max_jint, Type::WidenMin);
2348 }
2349 }
2350
2351 // If we are loading from a freshly-allocated object/array, produce a zero.
2352 // Things to check:
2353 // 1. Load is beyond the header: headers are not guaranteed to be zero
2354 // 2. Load is not vectorized: vectors have no zero constant
2355 // 3. Load has no matching store, i.e. the input is the initial memory state
2356 const TypeOopPtr* tinst = tp->isa_oopptr();
2357 bool is_not_header = (tinst != nullptr) && tinst->is_known_instance_field();
2358 bool is_not_vect = (_type->isa_vect() == nullptr);
2359 if (is_not_header && is_not_vect) {
2360 Node* mem = in(MemNode::Memory);
2361 if (mem->is_Parm() && mem->in(0)->is_Start()) {
2362 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
2363 return Type::get_zero_type(_type->basic_type());
2364 }
2365 }
2366
2367 if (!UseCompactObjectHeaders) {
2368 Node* alloc = is_new_object_mark_load();
2369 if (alloc != nullptr) {
2370 return TypeX::make(markWord::prototype().value());
2371 }
2372 }
2373
2374 return _type;
2375 }
2376
2377 //------------------------------match_edge-------------------------------------
2378 // Do we Match on this edge index or not? Match only the address.
2379 uint LoadNode::match_edge(uint idx) const {
2380 return idx == MemNode::Address;
2381 }
2382
2383 //--------------------------LoadBNode::Ideal--------------------------------------
2384 //
2385 // If the previous store is to the same address as this load,
2386 // and the value stored was larger than a byte, replace this load
2387 // with the value stored truncated to a byte. If no truncation is
2388 // needed, the replacement is done in LoadNode::Identity().
2389 //
2390 Node* LoadBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2391 Node* mem = in(MemNode::Memory);
2392 Node* value = can_see_stored_value_through_membars(mem, phase);
2393 if (value != nullptr) {
2394 Node* narrow = Compile::narrow_value(T_BYTE, value, _type, phase, false);
2395 if (narrow != value) {
2396 return narrow;
2397 }
2398 }
2399 // Identity call will handle the case where truncation is not needed.
2400 return LoadNode::Ideal(phase, can_reshape);
2401 }
2402
2403 const Type* LoadBNode::Value(PhaseGVN* phase) const {
2404 Node* mem = in(MemNode::Memory);
2405 Node* value = can_see_stored_value_through_membars(mem, phase);
2406 if (value != nullptr && value->is_Con() &&
2407 !value->bottom_type()->higher_equal(_type)) {
2408 // If the input to the store does not fit with the load's result type,
2409 // it must be truncated. We can't delay until Ideal call since
2410 // a singleton Value is needed for split_thru_phi optimization.
2411 int con = value->get_int();
2412 return TypeInt::make((con << 24) >> 24);
2413 }
2414 return LoadNode::Value(phase);
2415 }
2416
2417 //--------------------------LoadUBNode::Ideal-------------------------------------
2418 //
2419 // If the previous store is to the same address as this load,
2420 // and the value stored was larger than a byte, replace this load
2421 // with the value stored truncated to a byte. If no truncation is
2422 // needed, the replacement is done in LoadNode::Identity().
2423 //
2424 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2425 Node* mem = in(MemNode::Memory);
2426 Node* value = can_see_stored_value_through_membars(mem, phase);
2427 if (value != nullptr) {
2428 Node* narrow = Compile::narrow_value(T_BOOLEAN, value, _type, phase, false);
2429 if (narrow != value) {
2430 return narrow;
2431 }
2432 }
2433 // Identity call will handle the case where truncation is not needed.
2434 return LoadNode::Ideal(phase, can_reshape);
2435 }
2436
2437 const Type* LoadUBNode::Value(PhaseGVN* phase) const {
2438 Node* mem = in(MemNode::Memory);
2439 Node* value = can_see_stored_value_through_membars(mem, phase);
2440 if (value != nullptr && value->is_Con() &&
2441 !value->bottom_type()->higher_equal(_type)) {
2442 // If the input to the store does not fit with the load's result type,
2443 // it must be truncated. We can't delay until Ideal call since
2444 // a singleton Value is needed for split_thru_phi optimization.
2445 int con = value->get_int();
2446 return TypeInt::make(con & 0xFF);
2447 }
2448 return LoadNode::Value(phase);
2449 }
2450
2451 //--------------------------LoadUSNode::Ideal-------------------------------------
2452 //
2453 // If the previous store is to the same address as this load,
2454 // and the value stored was larger than a char, replace this load
2455 // with the value stored truncated to a char. If no truncation is
2456 // needed, the replacement is done in LoadNode::Identity().
2457 //
2458 Node* LoadUSNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2459 Node* mem = in(MemNode::Memory);
2460 Node* value = can_see_stored_value_through_membars(mem, phase);
2461 if (value != nullptr) {
2462 Node* narrow = Compile::narrow_value(T_CHAR, value, _type, phase, false);
2463 if (narrow != value) {
2464 return narrow;
2465 }
2466 }
2467 // Identity call will handle the case where truncation is not needed.
2468 return LoadNode::Ideal(phase, can_reshape);
2469 }
2470
2471 const Type* LoadUSNode::Value(PhaseGVN* phase) const {
2472 Node* mem = in(MemNode::Memory);
2473 Node* value = can_see_stored_value_through_membars(mem, phase);
2474 if (value != nullptr && value->is_Con() &&
2475 !value->bottom_type()->higher_equal(_type)) {
2476 // If the input to the store does not fit with the load's result type,
2477 // it must be truncated. We can't delay until Ideal call since
2478 // a singleton Value is needed for split_thru_phi optimization.
2479 int con = value->get_int();
2480 return TypeInt::make(con & 0xFFFF);
2481 }
2482 return LoadNode::Value(phase);
2483 }
2484
2485 //--------------------------LoadSNode::Ideal--------------------------------------
2486 //
2487 // If the previous store is to the same address as this load,
2488 // and the value stored was larger than a short, replace this load
2489 // with the value stored truncated to a short. If no truncation is
2490 // needed, the replacement is done in LoadNode::Identity().
2491 //
2492 Node* LoadSNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2493 Node* mem = in(MemNode::Memory);
2494 Node* value = can_see_stored_value_through_membars(mem, phase);
2495 if (value != nullptr) {
2496 Node* narrow = Compile::narrow_value(T_SHORT, value, _type, phase, false);
2497 if (narrow != value) {
2498 return narrow;
2499 }
2500 }
2501 // Identity call will handle the case where truncation is not needed.
2502 return LoadNode::Ideal(phase, can_reshape);
2503 }
2504
2505 const Type* LoadSNode::Value(PhaseGVN* phase) const {
2506 Node* mem = in(MemNode::Memory);
2507 Node* value = can_see_stored_value_through_membars(mem, phase);
2508 if (value != nullptr && value->is_Con() &&
2509 !value->bottom_type()->higher_equal(_type)) {
2510 // If the input to the store does not fit with the load's result type,
2511 // it must be truncated. We can't delay until Ideal call since
2512 // a singleton Value is needed for split_thru_phi optimization.
2513 int con = value->get_int();
2514 return TypeInt::make((con << 16) >> 16);
2515 }
2516 return LoadNode::Value(phase);
2517 }
2518
2519 //=============================================================================
2520 //----------------------------LoadKlassNode::make------------------------------
2521 // Polymorphic factory method:
2522 Node* LoadKlassNode::make(PhaseGVN& gvn, Node* mem, Node* adr, const TypePtr* at, const TypeKlassPtr* tk) {
2523 // sanity check the alias category against the created node type
2524 const TypePtr* adr_type = adr->bottom_type()->isa_ptr();
2525 assert(adr_type != nullptr, "expecting TypeKlassPtr");
2526 #ifdef _LP64
2527 if (adr_type->is_ptr_to_narrowklass()) {
2528 Node* load_klass = gvn.transform(new LoadNKlassNode(mem, adr, at, tk->make_narrowklass(), MemNode::unordered));
2529 return new DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr());
2530 }
2531 #endif
2532 assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
2533 return new LoadKlassNode(mem, adr, at, tk, MemNode::unordered);
2534 }
2535
2536 //------------------------------Value------------------------------------------
2537 const Type* LoadKlassNode::Value(PhaseGVN* phase) const {
2538 return klass_value_common(phase);
2539 }
2540
2541 const Type* LoadNode::klass_value_common(PhaseGVN* phase) const {
2542 // Either input is TOP ==> the result is TOP
2543 const Type *t1 = phase->type( in(MemNode::Memory) );
2544 if (t1 == Type::TOP) return Type::TOP;
2545 Node *adr = in(MemNode::Address);
2546 const Type *t2 = phase->type( adr );
2547 if (t2 == Type::TOP) return Type::TOP;
2548 const TypePtr *tp = t2->is_ptr();
2549 if (TypePtr::above_centerline(tp->ptr()) ||
2550 tp->ptr() == TypePtr::Null) return Type::TOP;
2551
2552 // Return a more precise klass, if possible
2553 const TypeInstPtr *tinst = tp->isa_instptr();
2554 if (tinst != nullptr) {
2555 ciInstanceKlass* ik = tinst->instance_klass();
2556 int offset = tinst->offset();
2557 if (ik == phase->C->env()->Class_klass()
2558 && (offset == java_lang_Class::klass_offset() ||
2559 offset == java_lang_Class::array_klass_offset())) {
2560 // We are loading a special hidden field from a Class mirror object,
2561 // the field which points to the VM's Klass metaobject.
2562 ciType* t = tinst->java_mirror_type();
2563 // java_mirror_type returns non-null for compile-time Class constants.
2564 if (t != nullptr) {
2565 // constant oop => constant klass
2566 if (offset == java_lang_Class::array_klass_offset()) {
2567 if (t->is_void()) {
2568 // We cannot create a void array. Since void is a primitive type return null
2569 // klass. Users of this result need to do a null check on the returned klass.
2570 return TypePtr::NULL_PTR;
2571 }
2572 return TypeKlassPtr::make(ciArrayKlass::make(t), Type::trust_interfaces);
2573 }
2574 if (!t->is_klass()) {
2575 // a primitive Class (e.g., int.class) has null for a klass field
2576 return TypePtr::NULL_PTR;
2577 }
2578 // Fold up the load of the hidden field
2579 return TypeKlassPtr::make(t->as_klass(), Type::trust_interfaces);
2580 }
2581 // non-constant mirror, so we can't tell what's going on
2582 }
2583 if (!tinst->is_loaded())
2584 return _type; // Bail out if not loaded
2585 if (offset == oopDesc::klass_offset_in_bytes()) {
2586 return tinst->as_klass_type(true);
2587 }
2588 }
2589
2590 // Check for loading klass from an array
2591 const TypeAryPtr *tary = tp->isa_aryptr();
2592 if (tary != nullptr &&
2593 tary->offset() == oopDesc::klass_offset_in_bytes()) {
2594 return tary->as_klass_type(true);
2595 }
2596
2597 // Check for loading klass from an array klass
2598 const TypeKlassPtr *tkls = tp->isa_klassptr();
2599 if (tkls != nullptr && !StressReflectiveCode) {
2600 if (!tkls->is_loaded())
2601 return _type; // Bail out if not loaded
2602 if (tkls->isa_aryklassptr() && tkls->is_aryklassptr()->elem()->isa_klassptr() &&
2603 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) {
2604 // // Always returning precise element type is incorrect,
2605 // // e.g., element type could be object and array may contain strings
2606 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
2607
2608 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
2609 // according to the element type's subclassing.
2610 return tkls->is_aryklassptr()->elem()->isa_klassptr()->cast_to_exactness(tkls->klass_is_exact());
2611 }
2612 if (tkls->isa_instklassptr() != nullptr && tkls->klass_is_exact() &&
2613 tkls->offset() == in_bytes(Klass::super_offset())) {
2614 ciKlass* sup = tkls->is_instklassptr()->instance_klass()->super();
2615 // The field is Klass::_super. Return its (constant) value.
2616 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
2617 return sup ? TypeKlassPtr::make(sup, Type::trust_interfaces) : TypePtr::NULL_PTR;
2618 }
2619 }
2620
2621 if (tkls != nullptr && !UseSecondarySupersCache
2622 && tkls->offset() == in_bytes(Klass::secondary_super_cache_offset())) {
2623 // Treat Klass::_secondary_super_cache as a constant when the cache is disabled.
2624 return TypePtr::NULL_PTR;
2625 }
2626
2627 // Bailout case
2628 return LoadNode::Value(phase);
2629 }
2630
2631 //------------------------------Identity---------------------------------------
2632 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
2633 // Also feed through the klass in Allocate(...klass...)._klass.
2634 Node* LoadKlassNode::Identity(PhaseGVN* phase) {
2635 return klass_identity_common(phase);
2636 }
2637
2638 Node* LoadNode::klass_identity_common(PhaseGVN* phase) {
2639 Node* x = LoadNode::Identity(phase);
2640 if (x != this) return x;
2641
2642 // Take apart the address into an oop and offset.
2643 // Return 'this' if we cannot.
2644 Node* adr = in(MemNode::Address);
2645 intptr_t offset = 0;
2646 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2647 if (base == nullptr) return this;
2648 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
2649 if (toop == nullptr) return this;
2650
2651 // Step over potential GC barrier for OopHandle resolve
2652 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
2653 if (bs->is_gc_barrier_node(base)) {
2654 base = bs->step_over_gc_barrier(base);
2655 }
2656
2657 // We can fetch the klass directly through an AllocateNode.
2658 // This works even if the klass is not constant (clone or newArray).
2659 if (offset == oopDesc::klass_offset_in_bytes()) {
2660 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
2661 if (allocated_klass != nullptr) {
2662 return allocated_klass;
2663 }
2664 }
2665
2666 // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*.
2667 // See inline_native_Class_query for occurrences of these patterns.
2668 // Java Example: x.getClass().isAssignableFrom(y)
2669 //
2670 // This improves reflective code, often making the Class
2671 // mirror go completely dead. (Current exception: Class
2672 // mirrors may appear in debug info, but we could clean them out by
2673 // introducing a new debug info operator for Klass.java_mirror).
2674
2675 if (toop->isa_instptr() && toop->is_instptr()->instance_klass() == phase->C->env()->Class_klass()
2676 && offset == java_lang_Class::klass_offset()) {
2677 if (base->is_Load()) {
2678 Node* base2 = base->in(MemNode::Address);
2679 if (base2->is_Load()) { /* direct load of a load which is the OopHandle */
2680 Node* adr2 = base2->in(MemNode::Address);
2681 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2682 if (tkls != nullptr && !tkls->empty()
2683 && (tkls->isa_instklassptr() || tkls->isa_aryklassptr())
2684 && adr2->is_AddP()
2685 ) {
2686 int mirror_field = in_bytes(Klass::java_mirror_offset());
2687 if (tkls->offset() == mirror_field) {
2688 #ifdef ASSERT
2689 const TypeKlassPtr* tkls2 = phase->type(adr2->in(AddPNode::Address))->is_klassptr();
2690 assert(tkls2->offset() == 0, "not a load of java_mirror");
2691 #endif
2692 assert(adr2->in(AddPNode::Base)->is_top(), "not an off heap load");
2693 assert(adr2->in(AddPNode::Offset)->find_intptr_t_con(-1) == in_bytes(Klass::java_mirror_offset()), "incorrect offset");
2694 return adr2->in(AddPNode::Address);
2695 }
2696 }
2697 }
2698 }
2699 }
2700
2701 return this;
2702 }
2703
2704 LoadNode* LoadNode::clone_pinned() const {
2705 LoadNode* ld = clone()->as_Load();
2706 ld->_control_dependency = UnknownControl;
2707 return ld;
2708 }
2709
2710 // Pin a LoadNode if it carries a dependency on its control input. There are cases when the node
2711 // does not actually have any dependency on its control input. For example, if we have a LoadNode
2712 // being used only outside a loop but it must be scheduled inside the loop, we can clone the node
2713 // for each of its use so that all the clones can be scheduled outside the loop. Then, to prevent
2714 // the clones from being GVN-ed again, we add a control input for each of them at the loop exit. In
2715 // those case, since there is not a dependency between the node and its control input, we do not
2716 // need to pin it.
2717 LoadNode* LoadNode::pin_node_under_control_impl() const {
2718 const TypePtr* adr_type = this->adr_type();
2719 if (adr_type != nullptr && adr_type->isa_aryptr()) {
2720 // Only array accesses have dependencies on their control input
2721 return clone_pinned();
2722 }
2723 return nullptr;
2724 }
2725
2726 //------------------------------Value------------------------------------------
2727 const Type* LoadNKlassNode::Value(PhaseGVN* phase) const {
2728 const Type *t = klass_value_common(phase);
2729 if (t == Type::TOP)
2730 return t;
2731
2732 return t->make_narrowklass();
2733 }
2734
2735 //------------------------------Identity---------------------------------------
2736 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
2737 // Also feed through the klass in Allocate(...klass...)._klass.
2738 Node* LoadNKlassNode::Identity(PhaseGVN* phase) {
2739 Node *x = klass_identity_common(phase);
2740
2741 const Type *t = phase->type( x );
2742 if( t == Type::TOP ) return x;
2743 if( t->isa_narrowklass()) return x;
2744 assert (!t->isa_narrowoop(), "no narrow oop here");
2745
2746 return phase->transform(new EncodePKlassNode(x, t->make_narrowklass()));
2747 }
2748
2749 //------------------------------Value-----------------------------------------
2750 const Type* LoadRangeNode::Value(PhaseGVN* phase) const {
2751 // Either input is TOP ==> the result is TOP
2752 const Type *t1 = phase->type( in(MemNode::Memory) );
2753 if( t1 == Type::TOP ) return Type::TOP;
2754 Node *adr = in(MemNode::Address);
2755 const Type *t2 = phase->type( adr );
2756 if( t2 == Type::TOP ) return Type::TOP;
2757 const TypePtr *tp = t2->is_ptr();
2758 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
2759 const TypeAryPtr *tap = tp->isa_aryptr();
2760 if( !tap ) return _type;
2761 return tap->size();
2762 }
2763
2764 //-------------------------------Ideal---------------------------------------
2765 // Feed through the length in AllocateArray(...length...)._length.
2766 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2767 Node* p = MemNode::Ideal_common(phase, can_reshape);
2768 if (p) return (p == NodeSentinel) ? nullptr : p;
2769
2770 // Take apart the address into an oop and offset.
2771 // Return 'this' if we cannot.
2772 Node* adr = in(MemNode::Address);
2773 intptr_t offset = 0;
2774 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2775 if (base == nullptr) return nullptr;
2776 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2777 if (tary == nullptr) return nullptr;
2778
2779 // We can fetch the length directly through an AllocateArrayNode.
2780 // This works even if the length is not constant (clone or newArray).
2781 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2782 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base);
2783 if (alloc != nullptr) {
2784 Node* allocated_length = alloc->Ideal_length();
2785 Node* len = alloc->make_ideal_length(tary, phase);
2786 if (allocated_length != len) {
2787 // New CastII improves on this.
2788 return len;
2789 }
2790 }
2791 }
2792
2793 return nullptr;
2794 }
2795
2796 //------------------------------Identity---------------------------------------
2797 // Feed through the length in AllocateArray(...length...)._length.
2798 Node* LoadRangeNode::Identity(PhaseGVN* phase) {
2799 Node* x = LoadINode::Identity(phase);
2800 if (x != this) return x;
2801
2802 // Take apart the address into an oop and offset.
2803 // Return 'this' if we cannot.
2804 Node* adr = in(MemNode::Address);
2805 intptr_t offset = 0;
2806 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2807 if (base == nullptr) return this;
2808 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2809 if (tary == nullptr) return this;
2810
2811 // We can fetch the length directly through an AllocateArrayNode.
2812 // This works even if the length is not constant (clone or newArray).
2813 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2814 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base);
2815 if (alloc != nullptr) {
2816 Node* allocated_length = alloc->Ideal_length();
2817 // Do not allow make_ideal_length to allocate a CastII node.
2818 Node* len = alloc->make_ideal_length(tary, phase, false);
2819 if (allocated_length == len) {
2820 // Return allocated_length only if it would not be improved by a CastII.
2821 return allocated_length;
2822 }
2823 }
2824 }
2825
2826 return this;
2827
2828 }
2829
2830 //=============================================================================
2831 //---------------------------StoreNode::make-----------------------------------
2832 // Polymorphic factory method:
2833 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) {
2834 assert((mo == unordered || mo == release), "unexpected");
2835 Compile* C = gvn.C;
2836 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");
2837 assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2838 ctl != nullptr, "raw memory operations should have control edge");
2839
2840 switch (bt) {
2841 case T_BOOLEAN: val = gvn.transform(new AndINode(val, gvn.intcon(0x1))); // Fall through to T_BYTE case
2842 case T_BYTE: return new StoreBNode(ctl, mem, adr, adr_type, val, mo);
2843 case T_INT: return new StoreINode(ctl, mem, adr, adr_type, val, mo);
2844 case T_CHAR:
2845 case T_SHORT: return new StoreCNode(ctl, mem, adr, adr_type, val, mo);
2846 case T_LONG: return new StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic_access);
2847 case T_FLOAT: return new StoreFNode(ctl, mem, adr, adr_type, val, mo);
2848 case T_DOUBLE: return new StoreDNode(ctl, mem, adr, adr_type, val, mo, require_atomic_access);
2849 case T_METADATA:
2850 case T_ADDRESS:
2851 case T_OBJECT:
2852 #ifdef _LP64
2853 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
2854 val = gvn.transform(new EncodePNode(val, val->bottom_type()->make_narrowoop()));
2855 return new StoreNNode(ctl, mem, adr, adr_type, val, mo);
2856 } else if (adr->bottom_type()->is_ptr_to_narrowklass() ||
2857 (val->bottom_type()->isa_klassptr() && adr->bottom_type()->isa_rawptr())) {
2858 val = gvn.transform(new EncodePKlassNode(val, val->bottom_type()->make_narrowklass()));
2859 return new StoreNKlassNode(ctl, mem, adr, adr_type, val, mo);
2860 }
2861 #endif
2862 {
2863 return new StorePNode(ctl, mem, adr, adr_type, val, mo);
2864 }
2865 default:
2866 ShouldNotReachHere();
2867 return (StoreNode*)nullptr;
2868 }
2869 }
2870
2871 //--------------------------bottom_type----------------------------------------
2872 const Type *StoreNode::bottom_type() const {
2873 return Type::MEMORY;
2874 }
2875
2876 //------------------------------hash-------------------------------------------
2877 uint StoreNode::hash() const {
2878 // unroll addition of interesting fields
2879 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2880
2881 // Since they are not commoned, do not hash them:
2882 return NO_HASH;
2883 }
2884
2885 // Link together multiple stores (B/S/C/I) into a longer one.
2886 //
2887 // Example: _store = StoreB[i+3]
2888 //
2889 // RangeCheck[i+0] RangeCheck[i+0]
2890 // StoreB[i+0]
2891 // RangeCheck[i+3] RangeCheck[i+3]
2892 // StoreB[i+1] --> pass: fail:
2893 // StoreB[i+2] StoreI[i+0] StoreB[i+0]
2894 // StoreB[i+3]
2895 //
2896 // The 4 StoreB are merged into a single StoreI node. We have to be careful with RangeCheck[i+1]: before
2897 // the optimization, if this RangeCheck[i+1] fails, then we execute only StoreB[i+0], and then trap. After
2898 // the optimization, the new StoreI[i+0] is on the passing path of RangeCheck[i+3], and StoreB[i+0] on the
2899 // failing path.
2900 //
2901 // Note: For normal array stores, every store at first has a RangeCheck. But they can be removed with:
2902 // - RCE (RangeCheck Elimination): the RangeChecks in the loop are hoisted out and before the loop,
2903 // and possibly no RangeChecks remain between the stores.
2904 // - RangeCheck smearing: the earlier RangeChecks are adjusted such that they cover later RangeChecks,
2905 // and those later RangeChecks can be removed. Example:
2906 //
2907 // RangeCheck[i+0] RangeCheck[i+0] <- before first store
2908 // StoreB[i+0] StoreB[i+0] <- first store
2909 // RangeCheck[i+1] --> smeared --> RangeCheck[i+3] <- only RC between first and last store
2910 // StoreB[i+1] StoreB[i+1] <- second store
2911 // RangeCheck[i+2] --> removed
2912 // StoreB[i+2] StoreB[i+2]
2913 // RangeCheck[i+3] --> removed
2914 // StoreB[i+3] StoreB[i+3] <- last store
2915 //
2916 // Thus, it is a common pattern that between the first and last store in a chain
2917 // of adjacent stores there remains exactly one RangeCheck, located between the
2918 // first and the second store (e.g. RangeCheck[i+3]).
2919 //
2920 class MergePrimitiveStores : public StackObj {
2921 private:
2922 PhaseGVN* const _phase;
2923 StoreNode* const _store;
2924 // State machine with initial state Unknown
2925 // Allowed transitions:
2926 // Unknown -> Const
2927 // Unknown -> Platform
2928 // Unknown -> Reverse
2929 // Unknown -> NotAdjacent
2930 // Const -> Const
2931 // Const -> NotAdjacent
2932 // Platform -> Platform
2933 // Platform -> NotAdjacent
2934 // Reverse -> Reverse
2935 // Reverse -> NotAdjacent
2936 // NotAdjacent -> NotAdjacent
2937 enum ValueOrder : uint8_t {
2938 Unknown, // Initial state
2939 Const, // Input values are const
2940 Platform, // Platform order
2941 Reverse, // Reverse platform order
2942 NotAdjacent // Not adjacent
2943 };
2944 ValueOrder _value_order;
2945
2946 NOT_PRODUCT( const CHeapBitMap &_trace_tags; )
2947
2948 public:
2949 MergePrimitiveStores(PhaseGVN* phase, StoreNode* store) :
2950 _phase(phase), _store(store), _value_order(ValueOrder::Unknown)
2951 NOT_PRODUCT( COMMA _trace_tags(Compile::current()->directive()->trace_merge_stores_tags()) )
2952 {}
2953
2954 StoreNode* run();
2955
2956 private:
2957 bool is_compatible_store(const StoreNode* other_store) const;
2958 bool is_adjacent_pair(const StoreNode* use_store, const StoreNode* def_store) const;
2959 bool is_adjacent_input_pair(const Node* n1, const Node* n2, const int memory_size) const;
2960 static bool is_con_RShift(const Node* n, Node const*& base_out, jint& shift_out, PhaseGVN* phase);
2961 enum CFGStatus { SuccessNoRangeCheck, SuccessWithRangeCheck, Failure };
2962 static CFGStatus cfg_status_for_pair(const StoreNode* use_store, const StoreNode* def_store);
2963
2964 class Status {
2965 private:
2966 StoreNode* _found_store;
2967 bool _found_range_check;
2968
2969 Status(StoreNode* found_store, bool found_range_check)
2970 : _found_store(found_store), _found_range_check(found_range_check) {}
2971
2972 public:
2973 StoreNode* found_store() const { return _found_store; }
2974 bool found_range_check() const { return _found_range_check; }
2975 static Status make_failure() { return Status(nullptr, false); }
2976
2977 static Status make(StoreNode* found_store, const CFGStatus cfg_status) {
2978 if (cfg_status == CFGStatus::Failure) {
2979 return Status::make_failure();
2980 }
2981 return Status(found_store, cfg_status == CFGStatus::SuccessWithRangeCheck);
2982 }
2983
2984 #ifndef PRODUCT
2985 void print_on(outputStream* st) const {
2986 if (_found_store == nullptr) {
2987 st->print_cr("None");
2988 } else {
2989 st->print_cr("Found[%d %s, %s]", _found_store->_idx, _found_store->Name(),
2990 _found_range_check ? "RC" : "no-RC");
2991 }
2992 }
2993 #endif
2994 };
2995
2996 enum ValueOrder find_adjacent_input_value_order(const Node* n1, const Node* n2, const int memory_size) const;
2997 Status find_adjacent_use_store(const StoreNode* def_store) const;
2998 Status find_adjacent_def_store(const StoreNode* use_store) const;
2999 Status find_use_store(const StoreNode* def_store) const;
3000 Status find_def_store(const StoreNode* use_store) const;
3001 Status find_use_store_unidirectional(const StoreNode* def_store) const;
3002 Status find_def_store_unidirectional(const StoreNode* use_store) const;
3003
3004 void collect_merge_list(Node_List& merge_list) const;
3005 Node* make_merged_input_value(const Node_List& merge_list);
3006 StoreNode* make_merged_store(const Node_List& merge_list, Node* merged_input_value);
3007
3008 #ifndef PRODUCT
3009 // Access to TraceMergeStores tags
3010 bool is_trace(TraceMergeStores::Tag tag) const {
3011 return _trace_tags.at(tag);
3012 }
3013
3014 bool is_trace_basic() const {
3015 return is_trace(TraceMergeStores::Tag::BASIC);
3016 }
3017
3018 bool is_trace_pointer_parsing() const {
3019 return is_trace(TraceMergeStores::Tag::POINTER_PARSING);
3020 }
3021
3022 bool is_trace_pointer_aliasing() const {
3023 return is_trace(TraceMergeStores::Tag::POINTER_ALIASING);
3024 }
3025
3026 bool is_trace_pointer_adjacency() const {
3027 return is_trace(TraceMergeStores::Tag::POINTER_ADJACENCY);
3028 }
3029
3030 bool is_trace_success() const {
3031 return is_trace(TraceMergeStores::Tag::SUCCESS);
3032 }
3033 #endif
3034
3035 NOT_PRODUCT( void trace(const Node_List& merge_list, const Node* merged_input_value, const StoreNode* merged_store) const; )
3036 };
3037
3038 StoreNode* MergePrimitiveStores::run() {
3039 // Check for B/S/C/I
3040 int opc = _store->Opcode();
3041 if (opc != Op_StoreB && opc != Op_StoreC && opc != Op_StoreI) {
3042 return nullptr;
3043 }
3044
3045 NOT_PRODUCT( if (is_trace_basic()) { tty->print("[TraceMergeStores] MergePrimitiveStores::run: "); _store->dump(); })
3046
3047 // The _store must be the "last" store in a chain. If we find a use we could merge with
3048 // then that use or a store further down is the "last" store.
3049 Status status_use = find_adjacent_use_store(_store);
3050 NOT_PRODUCT( if (is_trace_basic()) { tty->print("[TraceMergeStores] expect no use: "); status_use.print_on(tty); })
3051 if (status_use.found_store() != nullptr) {
3052 return nullptr;
3053 }
3054
3055 // Check if we can merge with at least one def, so that we have at least 2 stores to merge.
3056 Status status_def = find_adjacent_def_store(_store);
3057 NOT_PRODUCT( if (is_trace_basic()) { tty->print("[TraceMergeStores] expect def: "); status_def.print_on(tty); })
3058 Node* def_store = status_def.found_store();
3059 if (def_store == nullptr) {
3060 return nullptr;
3061 }
3062
3063 // Initialize value order
3064 _value_order = find_adjacent_input_value_order(def_store->in(MemNode::ValueIn),
3065 _store->in(MemNode::ValueIn),
3066 _store->memory_size());
3067 assert(_value_order != ValueOrder::NotAdjacent && _value_order != ValueOrder::Unknown, "Order should be checked");
3068
3069 ResourceMark rm;
3070 Node_List merge_list;
3071 collect_merge_list(merge_list);
3072
3073 Node* merged_input_value = make_merged_input_value(merge_list);
3074 if (merged_input_value == nullptr) { return nullptr; }
3075
3076 StoreNode* merged_store = make_merged_store(merge_list, merged_input_value);
3077
3078 NOT_PRODUCT( if (is_trace_success()) { trace(merge_list, merged_input_value, merged_store); } )
3079
3080 return merged_store;
3081 }
3082
3083 // Check compatibility between _store and other_store.
3084 bool MergePrimitiveStores::is_compatible_store(const StoreNode* other_store) const {
3085 int opc = _store->Opcode();
3086 assert(opc == Op_StoreB || opc == Op_StoreC || opc == Op_StoreI, "precondition");
3087
3088 if (other_store == nullptr ||
3089 _store->Opcode() != other_store->Opcode()) {
3090 return false;
3091 }
3092
3093 return true;
3094 }
3095
3096 bool MergePrimitiveStores::is_adjacent_pair(const StoreNode* use_store, const StoreNode* def_store) const {
3097 if (!is_adjacent_input_pair(def_store->in(MemNode::ValueIn),
3098 use_store->in(MemNode::ValueIn),
3099 def_store->memory_size())) {
3100 return false;
3101 }
3102
3103 ResourceMark rm;
3104 #ifndef PRODUCT
3105 const TraceMemPointer trace(is_trace_pointer_parsing(),
3106 is_trace_pointer_aliasing(),
3107 is_trace_pointer_adjacency(),
3108 true);
3109 #endif
3110 const MemPointer pointer_use(use_store NOT_PRODUCT(COMMA trace));
3111 const MemPointer pointer_def(def_store NOT_PRODUCT(COMMA trace));
3112 return pointer_def.is_adjacent_to_and_before(pointer_use);
3113 }
3114
3115 // Check input values n1 and n2 can be merged and return the value order
3116 MergePrimitiveStores::ValueOrder MergePrimitiveStores::find_adjacent_input_value_order(const Node* n1, const Node* n2,
3117 const int memory_size) const {
3118 // Pattern: [n1 = ConI, n2 = ConI]
3119 if (n1->Opcode() == Op_ConI && n2->Opcode() == Op_ConI) {
3120 return ValueOrder::Const;
3121 }
3122
3123 Node const *base_n2;
3124 jint shift_n2;
3125 if (!is_con_RShift(n2, base_n2, shift_n2, _phase)) {
3126 return ValueOrder::NotAdjacent;
3127 }
3128 Node const *base_n1;
3129 jint shift_n1;
3130 if (!is_con_RShift(n1, base_n1, shift_n1, _phase)) {
3131 return ValueOrder::NotAdjacent;
3132 }
3133
3134 int bits_per_store = memory_size * 8;
3135 if (base_n1 != base_n2 ||
3136 abs(shift_n1 - shift_n2) != bits_per_store ||
3137 shift_n1 % bits_per_store != 0) {
3138 // Values are not adjacent
3139 return ValueOrder::NotAdjacent;
3140 }
3141
3142 // Detect value order
3143 #ifdef VM_LITTLE_ENDIAN
3144 return shift_n1 < shift_n2 ? ValueOrder::Platform // Pattern: [n1 = base >> shift, n2 = base >> (shift + memory_size)]
3145 : ValueOrder::Reverse; // Pattern: [n1 = base >> (shift + memory_size), n2 = base >> shift]
3146 #else
3147 return shift_n1 > shift_n2 ? ValueOrder::Platform // Pattern: [n1 = base >> (shift + memory_size), n2 = base >> shift]
3148 : ValueOrder::Reverse; // Pattern: [n1 = base >> shift, n2 = base >> (shift + memory_size)]
3149 #endif
3150 }
3151
3152 bool MergePrimitiveStores::is_adjacent_input_pair(const Node* n1, const Node* n2, const int memory_size) const {
3153 ValueOrder input_value_order = find_adjacent_input_value_order(n1, n2, memory_size);
3154
3155 switch (input_value_order) {
3156 case ValueOrder::NotAdjacent:
3157 return false;
3158 case ValueOrder::Reverse:
3159 if (memory_size != 1 ||
3160 !Matcher::match_rule_supported(Op_ReverseBytesS) ||
3161 !Matcher::match_rule_supported(Op_ReverseBytesI) ||
3162 !Matcher::match_rule_supported(Op_ReverseBytesL)) {
3163 // ReverseBytes are not supported by platform
3164 return false;
3165 }
3166 // fall-through.
3167 case ValueOrder::Const:
3168 case ValueOrder::Platform:
3169 if (_value_order == ValueOrder::Unknown) {
3170 // Initial state is Unknown, and we find a valid input value order
3171 return true;
3172 }
3173 // The value order can not be changed
3174 return _value_order == input_value_order;
3175 case ValueOrder::Unknown:
3176 default:
3177 ShouldNotReachHere();
3178 }
3179 return false;
3180 }
3181
3182 // Detect pattern: n = base_out >> shift_out
3183 bool MergePrimitiveStores::is_con_RShift(const Node* n, Node const*& base_out, jint& shift_out, PhaseGVN* phase) {
3184 assert(n != nullptr, "precondition");
3185
3186 int opc = n->Opcode();
3187 if (opc == Op_ConvL2I) {
3188 n = n->in(1);
3189 opc = n->Opcode();
3190 }
3191
3192 if ((opc == Op_RShiftI ||
3193 opc == Op_RShiftL ||
3194 opc == Op_URShiftI ||
3195 opc == Op_URShiftL) &&
3196 n->in(2)->is_ConI()) {
3197 base_out = n->in(1);
3198 shift_out = n->in(2)->get_int();
3199 // The shift must be positive:
3200 return shift_out >= 0;
3201 }
3202
3203 if (phase->type(n)->isa_int() != nullptr ||
3204 phase->type(n)->isa_long() != nullptr) {
3205 // (base >> 0)
3206 base_out = n;
3207 shift_out = 0;
3208 return true;
3209 }
3210 return false;
3211 }
3212
3213 // Check if there is nothing between the two stores, except optionally a RangeCheck leading to an uncommon trap.
3214 MergePrimitiveStores::CFGStatus MergePrimitiveStores::cfg_status_for_pair(const StoreNode* use_store, const StoreNode* def_store) {
3215 assert(use_store->in(MemNode::Memory) == def_store, "use-def relationship");
3216
3217 Node* ctrl_use = use_store->in(MemNode::Control);
3218 Node* ctrl_def = def_store->in(MemNode::Control);
3219 if (ctrl_use == nullptr || ctrl_def == nullptr) {
3220 return CFGStatus::Failure;
3221 }
3222
3223 if (ctrl_use == ctrl_def) {
3224 // Same ctrl -> no RangeCheck in between.
3225 // Check: use_store must be the only use of def_store.
3226 if (def_store->outcnt() > 1) {
3227 return CFGStatus::Failure;
3228 }
3229 return CFGStatus::SuccessNoRangeCheck;
3230 }
3231
3232 // Different ctrl -> could have RangeCheck in between.
3233 // Check: 1. def_store only has these uses: use_store and MergeMem for uncommon trap, and
3234 // 2. ctrl separated by RangeCheck.
3235 if (def_store->outcnt() != 2) {
3236 return CFGStatus::Failure; // Cannot have exactly these uses: use_store and MergeMem for uncommon trap.
3237 }
3238 int use_store_out_idx = def_store->raw_out(0) == use_store ? 0 : 1;
3239 Node* merge_mem = def_store->raw_out(1 - use_store_out_idx)->isa_MergeMem();
3240 if (merge_mem == nullptr ||
3241 merge_mem->outcnt() != 1) {
3242 return CFGStatus::Failure; // Does not have MergeMem for uncommon trap.
3243 }
3244 if (!ctrl_use->is_IfProj() ||
3245 !ctrl_use->in(0)->is_RangeCheck() ||
3246 ctrl_use->in(0)->outcnt() != 2) {
3247 return CFGStatus::Failure; // Not RangeCheck.
3248 }
3249 IfProjNode* other_proj = ctrl_use->as_IfProj()->other_if_proj();
3250 Node* trap = other_proj->is_uncommon_trap_proj(Deoptimization::Reason_range_check);
3251 if (trap != merge_mem->unique_out() ||
3252 ctrl_use->in(0)->in(0) != ctrl_def) {
3253 return CFGStatus::Failure; // Not RangeCheck with merge_mem leading to uncommon trap.
3254 }
3255
3256 return CFGStatus::SuccessWithRangeCheck;
3257 }
3258
3259 MergePrimitiveStores::Status MergePrimitiveStores::find_adjacent_use_store(const StoreNode* def_store) const {
3260 Status status_use = find_use_store(def_store);
3261 StoreNode* use_store = status_use.found_store();
3262 if (use_store != nullptr && !is_adjacent_pair(use_store, def_store)) {
3263 return Status::make_failure();
3264 }
3265 return status_use;
3266 }
3267
3268 MergePrimitiveStores::Status MergePrimitiveStores::find_adjacent_def_store(const StoreNode* use_store) const {
3269 Status status_def = find_def_store(use_store);
3270 StoreNode* def_store = status_def.found_store();
3271 if (def_store != nullptr && !is_adjacent_pair(use_store, def_store)) {
3272 return Status::make_failure();
3273 }
3274 return status_def;
3275 }
3276
3277 MergePrimitiveStores::Status MergePrimitiveStores::find_use_store(const StoreNode* def_store) const {
3278 Status status_use = find_use_store_unidirectional(def_store);
3279
3280 #ifdef ASSERT
3281 StoreNode* use_store = status_use.found_store();
3282 if (use_store != nullptr) {
3283 Status status_def = find_def_store_unidirectional(use_store);
3284 assert(status_def.found_store() == def_store &&
3285 status_def.found_range_check() == status_use.found_range_check(),
3286 "find_use_store and find_def_store must be symmetric");
3287 }
3288 #endif
3289
3290 return status_use;
3291 }
3292
3293 MergePrimitiveStores::Status MergePrimitiveStores::find_def_store(const StoreNode* use_store) const {
3294 Status status_def = find_def_store_unidirectional(use_store);
3295
3296 #ifdef ASSERT
3297 StoreNode* def_store = status_def.found_store();
3298 if (def_store != nullptr) {
3299 Status status_use = find_use_store_unidirectional(def_store);
3300 assert(status_use.found_store() == use_store &&
3301 status_use.found_range_check() == status_def.found_range_check(),
3302 "find_use_store and find_def_store must be symmetric");
3303 }
3304 #endif
3305
3306 return status_def;
3307 }
3308
3309 MergePrimitiveStores::Status MergePrimitiveStores::find_use_store_unidirectional(const StoreNode* def_store) const {
3310 assert(is_compatible_store(def_store), "precondition: must be compatible with _store");
3311
3312 for (DUIterator_Fast imax, i = def_store->fast_outs(imax); i < imax; i++) {
3313 StoreNode* use_store = def_store->fast_out(i)->isa_Store();
3314 if (is_compatible_store(use_store)) {
3315 return Status::make(use_store, cfg_status_for_pair(use_store, def_store));
3316 }
3317 }
3318
3319 return Status::make_failure();
3320 }
3321
3322 MergePrimitiveStores::Status MergePrimitiveStores::find_def_store_unidirectional(const StoreNode* use_store) const {
3323 assert(is_compatible_store(use_store), "precondition: must be compatible with _store");
3324
3325 StoreNode* def_store = use_store->in(MemNode::Memory)->isa_Store();
3326 if (!is_compatible_store(def_store)) {
3327 return Status::make_failure();
3328 }
3329
3330 return Status::make(def_store, cfg_status_for_pair(use_store, def_store));
3331 }
3332
3333 void MergePrimitiveStores::collect_merge_list(Node_List& merge_list) const {
3334 // The merged store can be at most 8 bytes.
3335 const uint merge_list_max_size = 8 / _store->memory_size();
3336 assert(merge_list_max_size >= 2 &&
3337 merge_list_max_size <= 8 &&
3338 is_power_of_2(merge_list_max_size),
3339 "must be 2, 4 or 8");
3340
3341 // Traverse up the chain of adjacent def stores.
3342 StoreNode* current = _store;
3343 merge_list.push(current);
3344 while (current != nullptr && merge_list.size() < merge_list_max_size) {
3345 Status status = find_adjacent_def_store(current);
3346 NOT_PRODUCT( if (is_trace_basic()) { tty->print("[TraceMergeStores] find def: "); status.print_on(tty); })
3347
3348 current = status.found_store();
3349 if (current != nullptr) {
3350 merge_list.push(current);
3351
3352 // We can have at most one RangeCheck.
3353 if (status.found_range_check()) {
3354 NOT_PRODUCT( if (is_trace_basic()) { tty->print_cr("[TraceMergeStores] found RangeCheck, stop traversal."); })
3355 break;
3356 }
3357 }
3358 }
3359
3360 NOT_PRODUCT( if (is_trace_basic()) { tty->print_cr("[TraceMergeStores] found:"); merge_list.dump(); })
3361
3362 // Truncate the merge_list to a power of 2.
3363 const uint pow2size = round_down_power_of_2(merge_list.size());
3364 assert(pow2size >= 2, "must be merging at least 2 stores");
3365 while (merge_list.size() > pow2size) { merge_list.pop(); }
3366
3367 NOT_PRODUCT( if (is_trace_basic()) { tty->print_cr("[TraceMergeStores] truncated:"); merge_list.dump(); })
3368 }
3369
3370 // Merge the input values of the smaller stores to a single larger input value.
3371 Node* MergePrimitiveStores::make_merged_input_value(const Node_List& merge_list) {
3372 int new_memory_size = _store->memory_size() * merge_list.size();
3373 Node* first = merge_list.at(merge_list.size()-1);
3374 Node* merged_input_value = nullptr;
3375 if (_store->in(MemNode::ValueIn)->Opcode() == Op_ConI) {
3376 assert(_value_order == ValueOrder::Const, "must match");
3377 // Pattern: [ConI, ConI, ...] -> new constant
3378 jlong con = 0;
3379 jlong bits_per_store = _store->memory_size() * 8;
3380 jlong mask = (((jlong)1) << bits_per_store) - 1;
3381 for (uint i = 0; i < merge_list.size(); i++) {
3382 jlong con_i = merge_list.at(i)->in(MemNode::ValueIn)->get_int();
3383 #ifdef VM_LITTLE_ENDIAN
3384 con = con << bits_per_store;
3385 con = con | (mask & con_i);
3386 #else // VM_LITTLE_ENDIAN
3387 con_i = (mask & con_i) << (i * bits_per_store);
3388 con = con | con_i;
3389 #endif // VM_LITTLE_ENDIAN
3390 }
3391 merged_input_value = _phase->longcon(con);
3392 } else {
3393 assert(_value_order == ValueOrder::Platform || _value_order == ValueOrder::Reverse, "must match");
3394 // Pattern: [base >> 24, base >> 16, base >> 8, base] -> base
3395 // | |
3396 // _store first
3397 //
3398 Node* hi = _store->in(MemNode::ValueIn);
3399 Node* lo = first->in(MemNode::ValueIn);
3400 #ifndef VM_LITTLE_ENDIAN
3401 // `_store` and `first` are swapped in the diagram above
3402 swap(hi, lo);
3403 #endif // !VM_LITTLE_ENDIAN
3404 if (_value_order == ValueOrder::Reverse) {
3405 swap(hi, lo);
3406 }
3407 Node const* hi_base;
3408 jint hi_shift;
3409 merged_input_value = lo;
3410 bool is_true = is_con_RShift(hi, hi_base, hi_shift, _phase);
3411 assert(is_true, "must detect con RShift");
3412 if (merged_input_value != hi_base && merged_input_value->Opcode() == Op_ConvL2I) {
3413 // look through
3414 merged_input_value = merged_input_value->in(1);
3415 }
3416 if (merged_input_value != hi_base) {
3417 // merged_input_value is not the base
3418 return nullptr;
3419 }
3420 }
3421
3422 if (_phase->type(merged_input_value)->isa_long() != nullptr && new_memory_size <= 4) {
3423 // Example:
3424 //
3425 // long base = ...;
3426 // a[0] = (byte)(base >> 0);
3427 // a[1] = (byte)(base >> 8);
3428 //
3429 merged_input_value = _phase->transform(new ConvL2INode(merged_input_value));
3430 }
3431
3432 assert((_phase->type(merged_input_value)->isa_int() != nullptr && new_memory_size <= 4) ||
3433 (_phase->type(merged_input_value)->isa_long() != nullptr && new_memory_size == 8),
3434 "merged_input_value is either int or long, and new_memory_size is small enough");
3435
3436 if (_value_order == ValueOrder::Reverse) {
3437 assert(_store->memory_size() == 1, "only implemented for bytes");
3438 if (new_memory_size == 8) {
3439 merged_input_value = _phase->transform(new ReverseBytesLNode(merged_input_value));
3440 } else if (new_memory_size == 4) {
3441 merged_input_value = _phase->transform(new ReverseBytesINode(merged_input_value));
3442 } else {
3443 assert(new_memory_size == 2, "sanity check");
3444 merged_input_value = _phase->transform(new ReverseBytesSNode(merged_input_value));
3445 }
3446 }
3447 return merged_input_value;
3448 }
3449
3450 // //
3451 // first_ctrl first_mem first_adr first_ctrl first_mem first_adr //
3452 // | | | | | | //
3453 // | | | | +---------------+ | //
3454 // | | | | | | | //
3455 // | | +---------+ | | +---------------+ //
3456 // | | | | | | | | //
3457 // +--------------+ | | v1 +------------------------------+ | | v1 //
3458 // | | | | | | | | | | | | //
3459 // RangeCheck first_store RangeCheck | | first_store //
3460 // | | | | | | | //
3461 // last_ctrl | +----> unc_trap last_ctrl | | +----> unc_trap //
3462 // | | ===> | | | //
3463 // +--------------+ | a2 v2 | | | //
3464 // | | | | | | | | //
3465 // | second_store | | | //
3466 // | | | | | [v1 v2 ... vn] //
3467 // ... ... | | | | //
3468 // | | | | | v //
3469 // +--------------+ | an vn +--------------+ | | merged_input_value //
3470 // | | | | | | | | //
3471 // last_store (= _store) merged_store //
3472 // //
3473 StoreNode* MergePrimitiveStores::make_merged_store(const Node_List& merge_list, Node* merged_input_value) {
3474 Node* first_store = merge_list.at(merge_list.size()-1);
3475 Node* last_ctrl = _store->in(MemNode::Control); // after (optional) RangeCheck
3476 Node* first_mem = first_store->in(MemNode::Memory);
3477 Node* first_adr = first_store->in(MemNode::Address);
3478
3479 const TypePtr* new_adr_type = _store->adr_type();
3480
3481 int new_memory_size = _store->memory_size() * merge_list.size();
3482 BasicType bt = T_ILLEGAL;
3483 switch (new_memory_size) {
3484 case 2: bt = T_SHORT; break;
3485 case 4: bt = T_INT; break;
3486 case 8: bt = T_LONG; break;
3487 }
3488
3489 StoreNode* merged_store = StoreNode::make(*_phase, last_ctrl, first_mem, first_adr,
3490 new_adr_type, merged_input_value, bt, MemNode::unordered);
3491
3492 // Marking the store mismatched is sufficient to prevent reordering, since array stores
3493 // are all on the same slice. Hence, we need no barriers.
3494 merged_store->set_mismatched_access();
3495
3496 // Constants above may now also be be packed -> put candidate on worklist
3497 _phase->is_IterGVN()->_worklist.push(first_mem);
3498
3499 return merged_store;
3500 }
3501
3502 #ifndef PRODUCT
3503 void MergePrimitiveStores::trace(const Node_List& merge_list, const Node* merged_input_value, const StoreNode* merged_store) const {
3504 stringStream ss;
3505 ss.print_cr("[TraceMergeStores]: Replace");
3506 for (int i = (int)merge_list.size() - 1; i >= 0; i--) {
3507 merge_list.at(i)->dump("\n", false, &ss);
3508 }
3509 ss.print_cr("[TraceMergeStores]: with");
3510 merged_input_value->dump("\n", false, &ss);
3511 merged_store->dump("\n", false, &ss);
3512 tty->print("%s", ss.as_string());
3513 }
3514 #endif
3515
3516 //------------------------------Ideal------------------------------------------
3517 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
3518 // When a store immediately follows a relevant allocation/initialization,
3519 // try to capture it into the initialization, or hoist it above.
3520 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3521 Node* p = MemNode::Ideal_common(phase, can_reshape);
3522 if (p) return (p == NodeSentinel) ? nullptr : p;
3523
3524 Node* mem = in(MemNode::Memory);
3525 Node* address = in(MemNode::Address);
3526 Node* value = in(MemNode::ValueIn);
3527 // Back-to-back stores to same address? Fold em up. Generally
3528 // unsafe if I have intervening uses. Also unsafe for masked or
3529 // scatter vector stores as the wider store.
3530 if (!this->is_StoreVector() || this->Opcode() == Op_StoreVector) {
3531 Node* st = mem;
3532 // If Store 'st' has more than one use, we cannot fold 'st' away.
3533 // For example, 'st' might be the final state at a conditional
3534 // return. Or, 'st' might be used by some node which is live at
3535 // the same time 'st' is live, which might be unschedulable. So,
3536 // require exactly ONE user until such time as we clone 'mem' for
3537 // each of 'mem's uses (thus making the exactly-1-user-rule hold
3538 // true). Further, 'st' must be a contiguous store, otherwise
3539 // memory_size does not make sense for measuring overlap.
3540 while (st->is_Store() && st->outcnt() == 1 && (!st->is_StoreVector() || st->Opcode() == Op_StoreVector)) {
3541 // Looking at a dead closed cycle of memory?
3542 assert(st != st->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
3543 assert(Opcode() == st->Opcode() ||
3544 st->Opcode() == Op_StoreVector ||
3545 Opcode() == Op_StoreVector ||
3546 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw ||
3547 (Opcode() == Op_StoreL && st->Opcode() == Op_StoreI) || // expanded ClearArrayNode
3548 (Opcode() == Op_StoreI && st->Opcode() == Op_StoreL) || // initialization by arraycopy
3549 (is_mismatched_access() || st->as_Store()->is_mismatched_access()),
3550 "no mismatched stores, except on raw memory: %s %s", NodeClassNames[Opcode()], NodeClassNames[st->Opcode()]);
3551
3552 if (st->in(MemNode::Address)->eqv_uncast(address) &&
3553 st->as_Store()->memory_size() <= this->memory_size()) {
3554 assert(!is_predicated_vector() && !is_StoreVectorMasked() &&
3555 !is_StoreVectorScatter() && !is_StoreVectorScatterMasked() &&
3556 !st->is_predicated_vector() && !st->is_StoreVectorMasked() &&
3557 !st->is_StoreVectorScatter() && !st->is_StoreVectorScatterMasked(),
3558 "optimization only correct for full-width stores without holes");
3559 Node* use = st->raw_out(0);
3560 if (phase->is_IterGVN()) {
3561 phase->is_IterGVN()->rehash_node_delayed(use);
3562 }
3563 // It's OK to do this in the parser, since DU info is always accurate,
3564 // and the parser always refers to nodes via SafePointNode maps.
3565 use->set_req_X(MemNode::Memory, st->in(MemNode::Memory), phase);
3566 return this;
3567 }
3568 st = st->in(MemNode::Memory);
3569 }
3570 }
3571
3572
3573 // Capture an unaliased, unconditional, simple store into an initializer.
3574 // Or, if it is independent of the allocation, hoist it above the allocation.
3575 if (ReduceFieldZeroing && /*can_reshape &&*/
3576 mem->is_Proj() && mem->in(0)->is_Initialize()) {
3577 InitializeNode* init = mem->in(0)->as_Initialize();
3578 intptr_t offset = init->can_capture_store(this, phase, can_reshape);
3579 if (offset > 0) {
3580 Node* moved = init->capture_store(this, offset, phase, can_reshape);
3581 // If the InitializeNode captured me, it made a raw copy of me,
3582 // and I need to disappear.
3583 if (moved != nullptr) {
3584 // %%% hack to ensure that Ideal returns a new node:
3585 mem = MergeMemNode::make(mem);
3586 return mem; // fold me away
3587 }
3588 }
3589 }
3590
3591 // Fold reinterpret cast into memory operation:
3592 // StoreX mem (MoveY2X v) => StoreY mem v
3593 if (value->is_Move()) {
3594 const Type* vt = value->in(1)->bottom_type();
3595 if (has_reinterpret_variant(vt)) {
3596 if (phase->C->post_loop_opts_phase()) {
3597 return convert_to_reinterpret_store(*phase, value->in(1), vt);
3598 } else {
3599 phase->C->record_for_post_loop_opts_igvn(this); // attempt the transformation once loop opts are over
3600 }
3601 }
3602 }
3603
3604 if (MergeStores && UseUnalignedAccesses) {
3605 if (phase->C->merge_stores_phase()) {
3606 MergePrimitiveStores merge(phase, this);
3607 Node* progress = merge.run();
3608 if (progress != nullptr) { return progress; }
3609 } else {
3610 // We need to wait with merging stores until RangeCheck smearing has removed the RangeChecks during
3611 // the post loops IGVN phase. If we do it earlier, then there may still be some RangeChecks between
3612 // the stores, and we merge the wrong sequence of stores.
3613 // Example:
3614 // StoreI RangeCheck StoreI StoreI RangeCheck StoreI
3615 // Apply MergeStores:
3616 // StoreI RangeCheck [ StoreL ] RangeCheck StoreI
3617 // Remove more RangeChecks:
3618 // StoreI [ StoreL ] StoreI
3619 // But now it would have been better to do this instead:
3620 // [ StoreL ] [ StoreL ]
3621 phase->C->record_for_merge_stores_igvn(this);
3622 }
3623 }
3624
3625 return nullptr; // No further progress
3626 }
3627
3628 //------------------------------Value-----------------------------------------
3629 const Type* StoreNode::Value(PhaseGVN* phase) const {
3630 // Either input is TOP ==> the result is TOP
3631 const Type *t1 = phase->type( in(MemNode::Memory) );
3632 if( t1 == Type::TOP ) return Type::TOP;
3633 const Type *t2 = phase->type( in(MemNode::Address) );
3634 if( t2 == Type::TOP ) return Type::TOP;
3635 const Type *t3 = phase->type( in(MemNode::ValueIn) );
3636 if( t3 == Type::TOP ) return Type::TOP;
3637 return Type::MEMORY;
3638 }
3639
3640 //------------------------------Identity---------------------------------------
3641 // Remove redundant stores:
3642 // Store(m, p, Load(m, p)) changes to m.
3643 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
3644 Node* StoreNode::Identity(PhaseGVN* phase) {
3645 Node* mem = in(MemNode::Memory);
3646 Node* adr = in(MemNode::Address);
3647 Node* val = in(MemNode::ValueIn);
3648
3649 Node* result = this;
3650
3651 // Load then Store? Then the Store is useless
3652 if (val->is_Load() &&
3653 val->in(MemNode::Address)->eqv_uncast(adr) &&
3654 val->in(MemNode::Memory )->eqv_uncast(mem) &&
3655 val->as_Load()->store_Opcode() == Opcode()) {
3656 if (!is_StoreVector()) {
3657 result = mem;
3658 } else if (Opcode() == Op_StoreVector && val->Opcode() == Op_LoadVector &&
3659 as_StoreVector()->vect_type() == val->as_LoadVector()->vect_type()) {
3660 // Ensure both are not masked accesses or gathers/scatters and vector types are the same
3661 result = mem;
3662 }
3663 }
3664
3665 // Two stores in a row of the same value?
3666 if (result == this &&
3667 mem->is_Store() &&
3668 mem->in(MemNode::Address)->eqv_uncast(adr) &&
3669 mem->in(MemNode::ValueIn)->eqv_uncast(val) &&
3670 mem->Opcode() == Opcode()) {
3671 if (!is_StoreVector()) {
3672 result = mem;
3673 } else {
3674 const StoreVectorNode* store_vector = as_StoreVector();
3675 const StoreVectorNode* mem_vector = mem->as_StoreVector();
3676 const Node* store_indices = store_vector->indices();
3677 const Node* mem_indices = mem_vector->indices();
3678 const Node* store_mask = store_vector->mask();
3679 const Node* mem_mask = mem_vector->mask();
3680 // Ensure types, indices, and masks match
3681 if (store_vector->vect_type() == mem_vector->vect_type() &&
3682 ((store_indices == nullptr) == (mem_indices == nullptr) &&
3683 (store_indices == nullptr || store_indices->eqv_uncast(mem_indices))) &&
3684 ((store_mask == nullptr) == (mem_mask == nullptr) &&
3685 (store_mask == nullptr || store_mask->eqv_uncast(mem_mask)))) {
3686 result = mem;
3687 }
3688 }
3689 }
3690
3691 // Store of zero anywhere into a freshly-allocated object?
3692 // Then the store is useless.
3693 // (It must already have been captured by the InitializeNode.)
3694 if (result == this &&
3695 ReduceFieldZeroing && phase->type(val)->is_zero_type()) {
3696 // a newly allocated object is already all-zeroes everywhere
3697 if (mem->is_Proj() && mem->in(0)->is_Allocate()) {
3698 result = mem;
3699 }
3700
3701 if (result == this) {
3702 // the store may also apply to zero-bits in an earlier object
3703 Node* prev_mem = find_previous_store(phase);
3704 // Steps (a), (b): Walk past independent stores to find an exact match.
3705 if (prev_mem != nullptr) {
3706 if (prev_mem->is_top()) {
3707 // find_previous_store returns top when the access is dead
3708 return prev_mem;
3709 }
3710 Node* prev_val = can_see_stored_value(prev_mem, phase);
3711 if (prev_val != nullptr && prev_val == val) {
3712 // prev_val and val might differ by a cast; it would be good
3713 // to keep the more informative of the two.
3714 result = mem;
3715 }
3716 }
3717 }
3718 }
3719
3720 PhaseIterGVN* igvn = phase->is_IterGVN();
3721 if (result != this && igvn != nullptr) {
3722 MemBarNode* trailing = trailing_membar();
3723 if (trailing != nullptr) {
3724 #ifdef ASSERT
3725 const TypeOopPtr* t_oop = phase->type(in(Address))->isa_oopptr();
3726 assert(t_oop == nullptr || t_oop->is_known_instance_field(), "only for non escaping objects");
3727 #endif
3728 trailing->remove(igvn);
3729 }
3730 }
3731
3732 return result;
3733 }
3734
3735 //------------------------------match_edge-------------------------------------
3736 // Do we Match on this edge index or not? Match only memory & value
3737 uint StoreNode::match_edge(uint idx) const {
3738 return idx == MemNode::Address || idx == MemNode::ValueIn;
3739 }
3740
3741 //------------------------------cmp--------------------------------------------
3742 // Do not common stores up together. They generally have to be split
3743 // back up anyways, so do not bother.
3744 bool StoreNode::cmp( const Node &n ) const {
3745 return (&n == this); // Always fail except on self
3746 }
3747
3748 //------------------------------Ideal_masked_input-----------------------------
3749 // Check for a useless mask before a partial-word store
3750 // (StoreB ... (AndI valIn conIa) )
3751 // If (conIa & mask == mask) this simplifies to
3752 // (StoreB ... (valIn) )
3753 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
3754 Node *val = in(MemNode::ValueIn);
3755 if( val->Opcode() == Op_AndI ) {
3756 const TypeInt *t = phase->type( val->in(2) )->isa_int();
3757 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
3758 set_req_X(MemNode::ValueIn, val->in(1), phase);
3759 return this;
3760 }
3761 }
3762 return nullptr;
3763 }
3764
3765
3766 //------------------------------Ideal_sign_extended_input----------------------
3767 // Check for useless sign-extension before a partial-word store
3768 // (StoreB ... (RShiftI _ (LShiftI _ v conIL) conIR))
3769 // If (conIL == conIR && conIR <= num_rejected_bits) this simplifies to
3770 // (StoreB ... (v))
3771 // If (conIL > conIR) under some conditions, it can be simplified into
3772 // (StoreB ... (LShiftI _ v (conIL - conIR)))
3773 // This case happens when the value of the store was itself a left shift, that
3774 // gets merged into the inner left shift of the sign-extension. For instance,
3775 // if we have
3776 // array_of_shorts[0] = (short)(v << 2)
3777 // We get a structure such as:
3778 // (StoreB ... (RShiftI _ (LShiftI _ (LShiftI _ v 2) 16) 16))
3779 // that is simplified into
3780 // (StoreB ... (RShiftI _ (LShiftI _ v 18) 16)).
3781 // It is thus useful to handle cases where conIL > conIR. But this simplification
3782 // does not always hold. Let's see in which cases it's valid.
3783 //
3784 // Let's assume we have the following 32 bits integer v:
3785 // +----------------------------------+
3786 // | v[0..31] |
3787 // +----------------------------------+
3788 // 31 0
3789 // that will be stuffed in 8 bits byte after a shift left and a shift right of
3790 // potentially different magnitudes.
3791 // We denote num_rejected_bits the number of bits of the discarded part. In this
3792 // case, num_rejected_bits == 24.
3793 //
3794 // Statement (proved further below in case analysis):
3795 // Given:
3796 // - 0 <= conIL < BitsPerJavaInteger (no wrap in shift, enforced by maskShiftAmount)
3797 // - 0 <= conIR < BitsPerJavaInteger (no wrap in shift, enforced by maskShiftAmount)
3798 // - conIL >= conIR
3799 // - num_rejected_bits >= conIR
3800 // Then this form:
3801 // (RShiftI _ (LShiftI _ v conIL) conIR)
3802 // can be replaced with this form:
3803 // (LShiftI _ v (conIL-conIR))
3804 //
3805 // Note: We only have to show that the non-rejected lowest bits (8 bits for byte)
3806 // have to be correct, as the higher bits are rejected / truncated by the store.
3807 //
3808 // The hypotheses
3809 // 0 <= conIL < BitsPerJavaInteger
3810 // 0 <= conIR < BitsPerJavaInteger
3811 // are ensured by maskShiftAmount (called from ::Ideal of shift nodes). Indeed,
3812 // (v << 31) << 2 must be simplified into 0, not into v << 33 (which is equivalent
3813 // to v << 1).
3814 //
3815 //
3816 // If you don't like case analysis, jump after the conclusion.
3817 // ### Case 1 : conIL == conIR
3818 // ###### Case 1.1: conIL == conIR == num_rejected_bits
3819 // If we do the shift left then right by 24 bits, we get:
3820 // after: v << 24
3821 // +---------+------------------------+
3822 // | v[0..7] | 0 |
3823 // +---------+------------------------+
3824 // 31 24 23 0
3825 // after: (v << 24) >> 24
3826 // +------------------------+---------+
3827 // | sign bit | v[0..7] |
3828 // +------------------------+---------+
3829 // 31 8 7 0
3830 // The non-rejected bits (bits kept by the store, that is the 8 lower bits of the
3831 // result) are the same before and after, so, indeed, simplifying is correct.
3832
3833 // ###### Case 1.2: conIL == conIR < num_rejected_bits
3834 // If we do the shift left then right by 22 bits, we get:
3835 // after: v << 22
3836 // +---------+------------------------+
3837 // | v[0..9] | 0 |
3838 // +---------+------------------------+
3839 // 31 22 21 0
3840 // after: (v << 22) >> 22
3841 // +------------------------+---------+
3842 // | sign bit | v[0..9] |
3843 // +------------------------+---------+
3844 // 31 10 9 0
3845 // The non-rejected bits are the 8 lower bits of v. The bits 8 and 9 of v are still
3846 // present in (v << 22) >> 22 but will be dropped by the store. The simplification is
3847 // still correct.
3848
3849 // ###### But! Case 1.3: conIL == conIR > num_rejected_bits
3850 // If we do the shift left then right by 26 bits, we get:
3851 // after: v << 26
3852 // +---------+------------------------+
3853 // | v[0..5] | 0 |
3854 // +---------+------------------------+
3855 // 31 26 25 0
3856 // after: (v << 26) >> 26
3857 // +------------------------+---------+
3858 // | sign bit | v[0..5] |
3859 // +------------------------+---------+
3860 // 31 6 5 0
3861 // The non-rejected bits are made of
3862 // - 0-5 => the bits 0 to 5 of v
3863 // - 6-7 => the sign bit of v[0..5] (that is v[5])
3864 // Simplifying this as v is not correct.
3865 // The condition conIR <= num_rejected_bits is indeed necessary in Case 1
3866 //
3867 // ### Case 2: conIL > conIR
3868 // ###### Case 2.1: num_rejected_bits == conIR
3869 // We take conIL == 26 for this example.
3870 // after: v << 26
3871 // +---------+------------------------+
3872 // | v[0..5] | 0 |
3873 // +---------+------------------------+
3874 // 31 26 25 0
3875 // after: (v << 26) >> 24
3876 // +------------------+---------+-----+
3877 // | sign bit | v[0..5] | 0 |
3878 // +------------------+---------+-----+
3879 // 31 8 7 2 1 0
3880 // The non-rejected bits are the 8 lower ones of (v << conIL - conIR).
3881 // The bits 6 and 7 of v have been thrown away after the shift left.
3882 // The simplification is still correct.
3883 //
3884 // ###### Case 2.2: num_rejected_bits > conIR.
3885 // Let's say conIL == 26 and conIR == 22.
3886 // after: v << 26
3887 // +---------+------------------------+
3888 // | v[0..5] | 0 |
3889 // +---------+------------------------+
3890 // 31 26 25 0
3891 // after: (v << 26) >> 22
3892 // +------------------+---------+-----+
3893 // | sign bit | v[0..5] | 0 |
3894 // +------------------+---------+-----+
3895 // 31 10 9 4 3 0
3896 // The bits non-rejected by the store are exactly the 8 lower ones of (v << (conIL - conIR)):
3897 // - 0-3 => 0
3898 // - 4-7 => bits 0 to 3 of v
3899 // The simplification is still correct.
3900 // The bits 4 and 5 of v are still present in (v << (conIL - conIR)) but they don't
3901 // matter as they are not in the 8 lower bits: they will be cut out by the store.
3902 //
3903 // ###### But! Case 2.3: num_rejected_bits < conIR.
3904 // Let's see that this case is not as easy to simplify.
3905 // Let's say conIL == 28 and conIR == 26.
3906 // after: v << 28
3907 // +---------+------------------------+
3908 // | v[0..3] | 0 |
3909 // +---------+------------------------+
3910 // 31 28 27 0
3911 // after: (v << 28) >> 26
3912 // +------------------+---------+-----+
3913 // | sign bit | v[0..3] | 0 |
3914 // +------------------+---------+-----+
3915 // 31 6 5 2 1 0
3916 // The non-rejected bits are made of
3917 // - 0-1 => 0
3918 // - 2-5 => the bits 0 to 3 of v
3919 // - 6-7 => the sign bit of v[0..3] (that is v[3])
3920 // Simplifying this as (v << 2) is not correct.
3921 // The condition conIR <= num_rejected_bits is indeed necessary in Case 2.
3922 //
3923 // ### Conclusion:
3924 // Our hypotheses are indeed sufficient:
3925 // - 0 <= conIL < BitsPerJavaInteger
3926 // - 0 <= conIR < BitsPerJavaInteger
3927 // - conIL >= conIR
3928 // - num_rejected_bits >= conIR
3929 //
3930 // ### A rationale without case analysis:
3931 // After the shift left, conIL upper bits of v are discarded and conIL lower bit
3932 // zeroes are added. After the shift right, conIR lower bits of the previous result
3933 // are discarded. If conIL >= conIR, we discard only the zeroes we made up during
3934 // the shift left, but if conIL < conIR, then we discard also lower bits of v. But
3935 // the point of the simplification is to get an expression of the form
3936 // (v << (conIL - conIR)). This expression discard only higher bits of v, thus the
3937 // simplification is not correct if conIL < conIR.
3938 //
3939 // Moreover, after the shift right, the higher bit of (v << conIL) is repeated on the
3940 // conIR higher bits of ((v << conIL) >> conIR), it's the sign-extension. If
3941 // conIR > num_rejected_bits, then at least one artificial copy of this sign bit will
3942 // be in the window of the store. Thus ((v << conIL) >> conIR) is not equivalent to
3943 // (v << (conIL-conIR)) if conIR > num_rejected_bits.
3944 //
3945 // We do not treat the case conIL < conIR here since the point of this function is
3946 // to skip sign-extensions (that is conIL == conIR == num_rejected_bits). The need
3947 // of treating conIL > conIR comes from the cases where the sign-extended value is
3948 // also left-shift expression. Computing the sign-extension of a right-shift expression
3949 // doesn't yield a situation such as
3950 // (StoreB ... (RShiftI _ (LShiftI _ v conIL) conIR))
3951 // where conIL < conIR.
3952 Node* StoreNode::Ideal_sign_extended_input(PhaseGVN* phase, int num_rejected_bits) {
3953 Node* shr = in(MemNode::ValueIn);
3954 if (shr->Opcode() == Op_RShiftI) {
3955 const TypeInt* conIR = phase->type(shr->in(2))->isa_int();
3956 if (conIR != nullptr && conIR->is_con() && conIR->get_con() >= 0 && conIR->get_con() < BitsPerJavaInteger && conIR->get_con() <= num_rejected_bits) {
3957 Node* shl = shr->in(1);
3958 if (shl->Opcode() == Op_LShiftI) {
3959 const TypeInt* conIL = phase->type(shl->in(2))->isa_int();
3960 if (conIL != nullptr && conIL->is_con() && conIL->get_con() >= 0 && conIL->get_con() < BitsPerJavaInteger) {
3961 if (conIL->get_con() == conIR->get_con()) {
3962 set_req_X(MemNode::ValueIn, shl->in(1), phase);
3963 return this;
3964 }
3965 if (conIL->get_con() > conIR->get_con()) {
3966 Node* new_shl = phase->transform(new LShiftINode(shl->in(1), phase->intcon(conIL->get_con() - conIR->get_con())));
3967 set_req_X(MemNode::ValueIn, new_shl, phase);
3968 return this;
3969 }
3970 }
3971 }
3972 }
3973 }
3974 return nullptr;
3975 }
3976
3977 //------------------------------value_never_loaded-----------------------------------
3978 // Determine whether there are any possible loads of the value stored.
3979 // For simplicity, we actually check if there are any loads from the
3980 // address stored to, not just for loads of the value stored by this node.
3981 //
3982 bool StoreNode::value_never_loaded(PhaseValues* phase) const {
3983 Node *adr = in(Address);
3984 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
3985 if (adr_oop == nullptr)
3986 return false;
3987 if (!adr_oop->is_known_instance_field())
3988 return false; // if not a distinct instance, there may be aliases of the address
3989 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
3990 Node *use = adr->fast_out(i);
3991 if (use->is_Load() || use->is_LoadStore()) {
3992 return false;
3993 }
3994 }
3995 return true;
3996 }
3997
3998 MemBarNode* StoreNode::trailing_membar() const {
3999 if (is_release()) {
4000 MemBarNode* trailing_mb = nullptr;
4001 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
4002 Node* u = fast_out(i);
4003 if (u->is_MemBar()) {
4004 if (u->as_MemBar()->trailing_store()) {
4005 assert(u->Opcode() == Op_MemBarVolatile, "");
4006 assert(trailing_mb == nullptr, "only one");
4007 trailing_mb = u->as_MemBar();
4008 #ifdef ASSERT
4009 Node* leading = u->as_MemBar()->leading_membar();
4010 assert(leading->Opcode() == Op_MemBarRelease, "incorrect membar");
4011 assert(leading->as_MemBar()->leading_store(), "incorrect membar pair");
4012 assert(leading->as_MemBar()->trailing_membar() == u, "incorrect membar pair");
4013 #endif
4014 } else {
4015 assert(u->as_MemBar()->standalone(), "");
4016 }
4017 }
4018 }
4019 return trailing_mb;
4020 }
4021 return nullptr;
4022 }
4023
4024
4025 //=============================================================================
4026 //------------------------------Ideal------------------------------------------
4027 // If the store is from an AND mask that leaves the low bits untouched, then
4028 // we can skip the AND operation. If the store is from a sign-extension
4029 // (a left shift, then right shift) we can skip both.
4030 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
4031 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
4032 if( progress != nullptr ) return progress;
4033
4034 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
4035 if( progress != nullptr ) return progress;
4036
4037 // Finally check the default case
4038 return StoreNode::Ideal(phase, can_reshape);
4039 }
4040
4041 //=============================================================================
4042 //------------------------------Ideal------------------------------------------
4043 // If the store is from an AND mask that leaves the low bits untouched, then
4044 // we can skip the AND operation
4045 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
4046 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
4047 if( progress != nullptr ) return progress;
4048
4049 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
4050 if( progress != nullptr ) return progress;
4051
4052 // Finally check the default case
4053 return StoreNode::Ideal(phase, can_reshape);
4054 }
4055
4056 //=============================================================================
4057 //----------------------------------SCMemProjNode------------------------------
4058 const Type* SCMemProjNode::Value(PhaseGVN* phase) const
4059 {
4060 if (in(0) == nullptr || phase->type(in(0)) == Type::TOP) {
4061 return Type::TOP;
4062 }
4063 return bottom_type();
4064 }
4065
4066 //=============================================================================
4067 //----------------------------------LoadStoreNode------------------------------
4068 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required )
4069 : Node(required),
4070 _type(rt),
4071 _barrier_data(0)
4072 {
4073 init_req(MemNode::Control, c );
4074 init_req(MemNode::Memory , mem);
4075 init_req(MemNode::Address, adr);
4076 init_req(MemNode::ValueIn, val);
4077 init_class_id(Class_LoadStore);
4078 DEBUG_ONLY(_adr_type = at; adr_type();)
4079 }
4080
4081 //------------------------------Value-----------------------------------------
4082 const Type* LoadStoreNode::Value(PhaseGVN* phase) const {
4083 // Either input is TOP ==> the result is TOP
4084 if (!in(MemNode::Control) || phase->type(in(MemNode::Control)) == Type::TOP) {
4085 return Type::TOP;
4086 }
4087 const Type* t = phase->type(in(MemNode::Memory));
4088 if (t == Type::TOP) {
4089 return Type::TOP;
4090 }
4091 t = phase->type(in(MemNode::Address));
4092 if (t == Type::TOP) {
4093 return Type::TOP;
4094 }
4095 t = phase->type(in(MemNode::ValueIn));
4096 if (t == Type::TOP) {
4097 return Type::TOP;
4098 }
4099 return bottom_type();
4100 }
4101
4102 const TypePtr* LoadStoreNode::adr_type() const {
4103 const TypePtr* cross_check = DEBUG_ONLY(_adr_type) NOT_DEBUG(nullptr);
4104 return MemNode::calculate_adr_type(in(MemNode::Address)->bottom_type(), cross_check);
4105 }
4106
4107 uint LoadStoreNode::ideal_reg() const {
4108 return _type->ideal_reg();
4109 }
4110
4111 // This method conservatively checks if the result of a LoadStoreNode is
4112 // used, that is, if it returns true, then it is definitely the case that
4113 // the result of the node is not needed.
4114 // For example, GetAndAdd can be matched into a lock_add instead of a
4115 // lock_xadd if the result of LoadStoreNode::result_not_used() is true
4116 bool LoadStoreNode::result_not_used() const {
4117 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
4118 Node *x = fast_out(i);
4119 if (x->Opcode() == Op_SCMemProj || x->is_ReachabilityFence()) {
4120 continue;
4121 }
4122 if (x->bottom_type() == TypeTuple::MEMBAR &&
4123 !x->is_Call() &&
4124 x->Opcode() != Op_Blackhole) {
4125 continue;
4126 }
4127 return false;
4128 }
4129 return true;
4130 }
4131
4132 MemBarNode* LoadStoreNode::trailing_membar() const {
4133 MemBarNode* trailing = nullptr;
4134 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
4135 Node* u = fast_out(i);
4136 if (u->is_MemBar()) {
4137 if (u->as_MemBar()->trailing_load_store()) {
4138 assert(u->Opcode() == Op_MemBarAcquire, "");
4139 assert(trailing == nullptr, "only one");
4140 trailing = u->as_MemBar();
4141 #ifdef ASSERT
4142 Node* leading = trailing->leading_membar();
4143 assert(support_IRIW_for_not_multiple_copy_atomic_cpu || leading->Opcode() == Op_MemBarRelease, "incorrect membar");
4144 assert(leading->as_MemBar()->leading_load_store(), "incorrect membar pair");
4145 assert(leading->as_MemBar()->trailing_membar() == trailing, "incorrect membar pair");
4146 #endif
4147 } else {
4148 assert(u->as_MemBar()->standalone(), "wrong barrier kind");
4149 }
4150 }
4151 }
4152
4153 return trailing;
4154 }
4155
4156 uint LoadStoreNode::size_of() const { return sizeof(*this); }
4157
4158 #ifndef PRODUCT
4159 void LoadStoreNode::dump_spec(outputStream* st) const {
4160 if (in(MemNode::Address) == nullptr) {
4161 // node is dead
4162 return;
4163 }
4164 #ifndef ASSERT
4165 // fake the missing field
4166 const TypePtr* _adr_type = in(MemNode::Address)->bottom_type()->isa_ptr();
4167 #endif
4168 MemNode::dump_adr_type(_adr_type, st);
4169
4170 Compile* C = Compile::current();
4171 if (C->alias_type(_adr_type)->is_volatile()) {
4172 st->print(" Volatile!");
4173 }
4174 st->print(" barrier(0x%x)", _barrier_data);
4175 }
4176 #endif
4177
4178 //=============================================================================
4179 //----------------------------------LoadStoreConditionalNode--------------------
4180 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, nullptr, TypeInt::BOOL, 5) {
4181 init_req(ExpectedIn, ex );
4182 }
4183
4184 const Type* LoadStoreConditionalNode::Value(PhaseGVN* phase) const {
4185 // Either input is TOP ==> the result is TOP
4186 const Type* t = phase->type(in(ExpectedIn));
4187 if (t == Type::TOP) {
4188 return Type::TOP;
4189 }
4190 return LoadStoreNode::Value(phase);
4191 }
4192
4193 //=============================================================================
4194 //-------------------------------adr_type--------------------------------------
4195 const TypePtr* ClearArrayNode::adr_type() const {
4196 Node *adr = in(3);
4197 if (adr == nullptr) return nullptr; // node is dead
4198 return MemNode::calculate_adr_type(adr->bottom_type());
4199 }
4200
4201 //------------------------------match_edge-------------------------------------
4202 // Do we Match on this edge index or not? Do not match memory
4203 uint ClearArrayNode::match_edge(uint idx) const {
4204 return idx > 1;
4205 }
4206
4207 //------------------------------Identity---------------------------------------
4208 // Clearing a zero length array does nothing
4209 Node* ClearArrayNode::Identity(PhaseGVN* phase) {
4210 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
4211 }
4212
4213 //------------------------------Idealize---------------------------------------
4214 // Clearing a short array is faster with stores
4215 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4216 // Already know this is a large node, do not try to ideal it
4217 if (_is_large) return nullptr;
4218
4219 const int unit = BytesPerLong;
4220 const TypeX* t = phase->type(in(2))->isa_intptr_t();
4221 if (!t) return nullptr;
4222 if (!t->is_con()) return nullptr;
4223 intptr_t raw_count = t->get_con();
4224 intptr_t size = raw_count;
4225 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
4226 // Clearing nothing uses the Identity call.
4227 // Negative clears are possible on dead ClearArrays
4228 // (see jck test stmt114.stmt11402.val).
4229 if (size <= 0 || size % unit != 0) return nullptr;
4230 intptr_t count = size / unit;
4231 // Length too long; communicate this to matchers and assemblers.
4232 // Assemblers are responsible to produce fast hardware clears for it.
4233 if (size > InitArrayShortSize) {
4234 return new ClearArrayNode(in(0), in(1), in(2), in(3), true);
4235 } else if (size > 2 && Matcher::match_rule_supported_vector(Op_ClearArray, 4, T_LONG)) {
4236 return nullptr;
4237 }
4238 if (!IdealizeClearArrayNode) return nullptr;
4239 Node *mem = in(1);
4240 if( phase->type(mem)==Type::TOP ) return nullptr;
4241 Node *adr = in(3);
4242 const Type* at = phase->type(adr);
4243 if( at==Type::TOP ) return nullptr;
4244 const TypePtr* atp = at->isa_ptr();
4245 // adjust atp to be the correct array element address type
4246 if (atp == nullptr) atp = TypePtr::BOTTOM;
4247 else atp = atp->add_offset(Type::OffsetBot);
4248 // Get base for derived pointer purposes
4249 if( adr->Opcode() != Op_AddP ) Unimplemented();
4250 Node *base = adr->in(1);
4251
4252 Node *zero = phase->makecon(TypeLong::ZERO);
4253 Node *off = phase->MakeConX(BytesPerLong);
4254 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
4255 count--;
4256 while (count--) {
4257 mem = phase->transform(mem);
4258 adr = phase->transform(AddPNode::make_with_base(base, adr, off));
4259 mem = new StoreLNode(in(0), mem, adr, atp, zero, MemNode::unordered, false);
4260 }
4261 return mem;
4262 }
4263
4264 //----------------------------step_through----------------------------------
4265 // Return allocation input memory edge if it is different instance
4266 // or itself if it is the one we are looking for.
4267 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseValues* phase) {
4268 Node* n = *np;
4269 assert(n->is_ClearArray(), "sanity");
4270 intptr_t offset;
4271 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
4272 // This method is called only before Allocate nodes are expanded
4273 // during macro nodes expansion. Before that ClearArray nodes are
4274 // only generated in PhaseMacroExpand::generate_arraycopy() (before
4275 // Allocate nodes are expanded) which follows allocations.
4276 assert(alloc != nullptr, "should have allocation");
4277 if (alloc->_idx == instance_id) {
4278 // Can not bypass initialization of the instance we are looking for.
4279 return false;
4280 }
4281 // Otherwise skip it.
4282 InitializeNode* init = alloc->initialization();
4283 if (init != nullptr)
4284 *np = init->in(TypeFunc::Memory);
4285 else
4286 *np = alloc->in(TypeFunc::Memory);
4287 return true;
4288 }
4289
4290 Node* ClearArrayNode::make_address(Node* dest, Node* offset, bool raw_base, PhaseGVN* phase) {
4291 Node* base = dest;
4292 if (raw_base) {
4293 // May be called as part of the initialization of a just allocated object
4294 base = phase->C->top();
4295 }
4296 return phase->transform(AddPNode::make_with_base(base, dest, offset));
4297 }
4298
4299 //----------------------------clear_memory-------------------------------------
4300 // Generate code to initialize object storage to zero.
4301 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
4302 intptr_t start_offset,
4303 Node* end_offset,
4304 bool raw_base,
4305 PhaseGVN* phase) {
4306 intptr_t offset = start_offset;
4307
4308 int unit = BytesPerLong;
4309 if ((offset % unit) != 0) {
4310 Node* adr = make_address(dest, phase->MakeConX(offset), raw_base, phase);
4311 const TypePtr* atp = TypeRawPtr::BOTTOM;
4312 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
4313 mem = phase->transform(mem);
4314 offset += BytesPerInt;
4315 }
4316 assert((offset % unit) == 0, "");
4317
4318 // Initialize the remaining stuff, if any, with a ClearArray.
4319 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, raw_base, phase);
4320 }
4321
4322 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
4323 Node* start_offset,
4324 Node* end_offset,
4325 bool raw_base,
4326 PhaseGVN* phase) {
4327 if (start_offset == end_offset) {
4328 // nothing to do
4329 return mem;
4330 }
4331
4332 int unit = BytesPerLong;
4333 Node* zbase = start_offset;
4334 Node* zend = end_offset;
4335
4336 // Scale to the unit required by the CPU:
4337 if (!Matcher::init_array_count_is_in_bytes) {
4338 Node* shift = phase->intcon(exact_log2(unit));
4339 zbase = phase->transform(new URShiftXNode(zbase, shift) );
4340 zend = phase->transform(new URShiftXNode(zend, shift) );
4341 }
4342
4343 // Bulk clear double-words
4344 Node* zsize = phase->transform(new SubXNode(zend, zbase) );
4345 Node* adr = make_address(dest, start_offset, raw_base, phase);
4346 mem = new ClearArrayNode(ctl, mem, zsize, adr, false);
4347 return phase->transform(mem);
4348 }
4349
4350 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
4351 intptr_t start_offset,
4352 intptr_t end_offset,
4353 bool raw_base,
4354 PhaseGVN* phase) {
4355 if (start_offset == end_offset) {
4356 // nothing to do
4357 return mem;
4358 }
4359
4360 assert((end_offset % BytesPerInt) == 0, "odd end offset");
4361 intptr_t done_offset = end_offset;
4362 if ((done_offset % BytesPerLong) != 0) {
4363 done_offset -= BytesPerInt;
4364 }
4365 if (done_offset > start_offset) {
4366 mem = clear_memory(ctl, mem, dest,
4367 start_offset, phase->MakeConX(done_offset), raw_base, phase);
4368 }
4369 if (done_offset < end_offset) { // emit the final 32-bit store
4370 Node* adr = make_address(dest, phase->MakeConX(done_offset), raw_base, phase);
4371 const TypePtr* atp = TypeRawPtr::BOTTOM;
4372 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
4373 mem = phase->transform(mem);
4374 done_offset += BytesPerInt;
4375 }
4376 assert(done_offset == end_offset, "");
4377 return mem;
4378 }
4379
4380 //=============================================================================
4381 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
4382 : MultiNode(TypeFunc::Parms + (precedent == nullptr? 0: 1)),
4383 _adr_type(C->get_adr_type(alias_idx)), _kind(Standalone)
4384 #ifdef ASSERT
4385 , _pair_idx(0)
4386 #endif
4387 {
4388 init_class_id(Class_MemBar);
4389 Node* top = C->top();
4390 init_req(TypeFunc::I_O,top);
4391 init_req(TypeFunc::FramePtr,top);
4392 init_req(TypeFunc::ReturnAdr,top);
4393 if (precedent != nullptr)
4394 init_req(TypeFunc::Parms, precedent);
4395 }
4396
4397 //------------------------------cmp--------------------------------------------
4398 uint MemBarNode::hash() const { return NO_HASH; }
4399 bool MemBarNode::cmp( const Node &n ) const {
4400 return (&n == this); // Always fail except on self
4401 }
4402
4403 //------------------------------make-------------------------------------------
4404 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
4405 switch (opcode) {
4406 case Op_MemBarAcquire: return new MemBarAcquireNode(C, atp, pn);
4407 case Op_LoadFence: return new LoadFenceNode(C, atp, pn);
4408 case Op_MemBarRelease: return new MemBarReleaseNode(C, atp, pn);
4409 case Op_StoreFence: return new StoreFenceNode(C, atp, pn);
4410 case Op_MemBarStoreStore: return new MemBarStoreStoreNode(C, atp, pn);
4411 case Op_StoreStoreFence: return new StoreStoreFenceNode(C, atp, pn);
4412 case Op_MemBarAcquireLock: return new MemBarAcquireLockNode(C, atp, pn);
4413 case Op_MemBarReleaseLock: return new MemBarReleaseLockNode(C, atp, pn);
4414 case Op_MemBarStoreLoad: return new MemBarStoreLoadNode(C, atp, pn);
4415 case Op_MemBarVolatile: return new MemBarVolatileNode(C, atp, pn);
4416 case Op_MemBarFull: return new MemBarFullNode(C, atp, pn);
4417 case Op_MemBarCPUOrder: return new MemBarCPUOrderNode(C, atp, pn);
4418 case Op_OnSpinWait: return new OnSpinWaitNode(C, atp, pn);
4419 case Op_Initialize: return new InitializeNode(C, atp, pn);
4420 default: ShouldNotReachHere(); return nullptr;
4421 }
4422 }
4423
4424 void MemBarNode::remove(PhaseIterGVN *igvn) {
4425 assert(outcnt() > 0 && (outcnt() <= 2 || Opcode() == Op_Initialize), "Only one or two out edges allowed");
4426 if (trailing_store() || trailing_load_store()) {
4427 MemBarNode* leading = leading_membar();
4428 if (leading != nullptr) {
4429 assert(leading->trailing_membar() == this, "inconsistent leading/trailing membars");
4430 leading->remove(igvn);
4431 }
4432 }
4433 if (proj_out_or_null(TypeFunc::Control) != nullptr) {
4434 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
4435 }
4436 if (is_Initialize()) {
4437 as_Initialize()->replace_mem_projs_by(in(TypeFunc::Memory), igvn);
4438 } else {
4439 if (proj_out_or_null(TypeFunc::Memory) != nullptr) {
4440 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
4441 }
4442 }
4443 }
4444
4445 //------------------------------Ideal------------------------------------------
4446 // Return a node which is more "ideal" than the current node. Strip out
4447 // control copies
4448 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4449 if (remove_dead_region(phase, can_reshape)) return this;
4450 // Don't bother trying to transform a dead node
4451 if (in(0) && in(0)->is_top()) {
4452 return nullptr;
4453 }
4454
4455 bool progress = false;
4456 // Eliminate volatile MemBars for scalar replaced objects.
4457 if (can_reshape && req() == (Precedent+1)) {
4458 bool eliminate = false;
4459 int opc = Opcode();
4460 if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) {
4461 // Volatile field loads and stores.
4462 Node* my_mem = in(MemBarNode::Precedent);
4463 // The MembarAquire may keep an unused LoadNode alive through the Precedent edge
4464 if ((my_mem != nullptr) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) {
4465 // if the Precedent is a decodeN and its input (a Load) is used at more than one place,
4466 // replace this Precedent (decodeN) with the Load instead.
4467 if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1)) {
4468 Node* load_node = my_mem->in(1);
4469 set_req(MemBarNode::Precedent, load_node);
4470 phase->is_IterGVN()->_worklist.push(my_mem);
4471 my_mem = load_node;
4472 } else {
4473 assert(my_mem->unique_out() == this, "sanity");
4474 assert(!trailing_load_store(), "load store node can't be eliminated");
4475 del_req(Precedent);
4476 phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later
4477 my_mem = nullptr;
4478 }
4479 progress = true;
4480 }
4481 if (my_mem != nullptr && my_mem->is_Mem()) {
4482 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
4483 // Check for scalar replaced object reference.
4484 if( t_oop != nullptr && t_oop->is_known_instance_field() &&
4485 t_oop->offset() != Type::OffsetBot &&
4486 t_oop->offset() != Type::OffsetTop) {
4487 eliminate = true;
4488 }
4489 }
4490 } else if (opc == Op_MemBarRelease || (UseStoreStoreForCtor && opc == Op_MemBarStoreStore)) {
4491 // Final field stores.
4492 Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent));
4493 if ((alloc != nullptr) && alloc->is_Allocate() &&
4494 alloc->as_Allocate()->does_not_escape_thread()) {
4495 // The allocated object does not escape.
4496 eliminate = true;
4497 }
4498 }
4499 if (eliminate) {
4500 // Replace MemBar projections by its inputs.
4501 PhaseIterGVN* igvn = phase->is_IterGVN();
4502 remove(igvn);
4503 // Must return either the original node (now dead) or a new node
4504 // (Do not return a top here, since that would break the uniqueness of top.)
4505 return new ConINode(TypeInt::ZERO);
4506 }
4507 }
4508 return progress ? this : nullptr;
4509 }
4510
4511 //------------------------------Value------------------------------------------
4512 const Type* MemBarNode::Value(PhaseGVN* phase) const {
4513 if( !in(0) ) return Type::TOP;
4514 if( phase->type(in(0)) == Type::TOP )
4515 return Type::TOP;
4516 return TypeTuple::MEMBAR;
4517 }
4518
4519 //------------------------------match------------------------------------------
4520 // Construct projections for memory.
4521 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) {
4522 switch (proj->_con) {
4523 case TypeFunc::Control:
4524 case TypeFunc::Memory:
4525 return new MachProjNode(this, proj->_con, RegMask::EMPTY, MachProjNode::unmatched_proj);
4526 }
4527 ShouldNotReachHere();
4528 return nullptr;
4529 }
4530
4531 void MemBarNode::set_store_pair(MemBarNode* leading, MemBarNode* trailing) {
4532 trailing->_kind = TrailingStore;
4533 leading->_kind = LeadingStore;
4534 #ifdef ASSERT
4535 trailing->_pair_idx = leading->_idx;
4536 leading->_pair_idx = leading->_idx;
4537 #endif
4538 }
4539
4540 void MemBarNode::set_load_store_pair(MemBarNode* leading, MemBarNode* trailing) {
4541 trailing->_kind = TrailingLoadStore;
4542 leading->_kind = LeadingLoadStore;
4543 #ifdef ASSERT
4544 trailing->_pair_idx = leading->_idx;
4545 leading->_pair_idx = leading->_idx;
4546 #endif
4547 }
4548
4549 MemBarNode* MemBarNode::trailing_membar() const {
4550 ResourceMark rm;
4551 Node* trailing = (Node*)this;
4552 VectorSet seen;
4553 Node_Stack multis(0);
4554 do {
4555 Node* c = trailing;
4556 uint i = 0;
4557 do {
4558 trailing = nullptr;
4559 for (; i < c->outcnt(); i++) {
4560 Node* next = c->raw_out(i);
4561 if (next != c && next->is_CFG()) {
4562 if (c->is_MultiBranch()) {
4563 if (multis.node() == c) {
4564 multis.set_index(i+1);
4565 } else {
4566 multis.push(c, i+1);
4567 }
4568 }
4569 trailing = next;
4570 break;
4571 }
4572 }
4573 if (trailing != nullptr && !seen.test_set(trailing->_idx)) {
4574 break;
4575 }
4576 while (multis.size() > 0) {
4577 c = multis.node();
4578 i = multis.index();
4579 if (i < c->req()) {
4580 break;
4581 }
4582 multis.pop();
4583 }
4584 } while (multis.size() > 0);
4585 } while (!trailing->is_MemBar() || !trailing->as_MemBar()->trailing());
4586
4587 MemBarNode* mb = trailing->as_MemBar();
4588 assert((mb->_kind == TrailingStore && _kind == LeadingStore) ||
4589 (mb->_kind == TrailingLoadStore && _kind == LeadingLoadStore), "bad trailing membar");
4590 assert(mb->_pair_idx == _pair_idx, "bad trailing membar");
4591 return mb;
4592 }
4593
4594 MemBarNode* MemBarNode::leading_membar() const {
4595 ResourceMark rm;
4596 VectorSet seen;
4597 Node_Stack regions(0);
4598 Node* leading = in(0);
4599 while (leading != nullptr && (!leading->is_MemBar() || !leading->as_MemBar()->leading())) {
4600 while (leading == nullptr || leading->is_top() || seen.test_set(leading->_idx)) {
4601 leading = nullptr;
4602 while (regions.size() > 0 && leading == nullptr) {
4603 Node* r = regions.node();
4604 uint i = regions.index();
4605 if (i < r->req()) {
4606 leading = r->in(i);
4607 regions.set_index(i+1);
4608 } else {
4609 regions.pop();
4610 }
4611 }
4612 if (leading == nullptr) {
4613 assert(regions.size() == 0, "all paths should have been tried");
4614 return nullptr;
4615 }
4616 }
4617 if (leading->is_Region()) {
4618 regions.push(leading, 2);
4619 leading = leading->in(1);
4620 } else {
4621 leading = leading->in(0);
4622 }
4623 }
4624 #ifdef ASSERT
4625 Unique_Node_List wq;
4626 wq.push((Node*)this);
4627 uint found = 0;
4628 for (uint i = 0; i < wq.size(); i++) {
4629 Node* n = wq.at(i);
4630 if (n->is_Region()) {
4631 for (uint j = 1; j < n->req(); j++) {
4632 Node* in = n->in(j);
4633 if (in != nullptr && !in->is_top()) {
4634 wq.push(in);
4635 }
4636 }
4637 } else {
4638 if (n->is_MemBar() && n->as_MemBar()->leading()) {
4639 assert(n == leading, "consistency check failed");
4640 found++;
4641 } else {
4642 Node* in = n->in(0);
4643 if (in != nullptr && !in->is_top()) {
4644 wq.push(in);
4645 }
4646 }
4647 }
4648 }
4649 assert(found == 1 || (found == 0 && leading == nullptr), "consistency check failed");
4650 #endif
4651 if (leading == nullptr) {
4652 return nullptr;
4653 }
4654 MemBarNode* mb = leading->as_MemBar();
4655 assert((mb->_kind == LeadingStore && _kind == TrailingStore) ||
4656 (mb->_kind == LeadingLoadStore && _kind == TrailingLoadStore), "bad leading membar");
4657 assert(mb->_pair_idx == _pair_idx, "bad leading membar");
4658 return mb;
4659 }
4660
4661
4662 //===========================InitializeNode====================================
4663 // SUMMARY:
4664 // This node acts as a memory barrier on raw memory, after some raw stores.
4665 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
4666 // The Initialize can 'capture' suitably constrained stores as raw inits.
4667 // It can coalesce related raw stores into larger units (called 'tiles').
4668 // It can avoid zeroing new storage for memory units which have raw inits.
4669 // At macro-expansion, it is marked 'complete', and does not optimize further.
4670 //
4671 // EXAMPLE:
4672 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
4673 // ctl = incoming control; mem* = incoming memory
4674 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
4675 // First allocate uninitialized memory and fill in the header:
4676 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
4677 // ctl := alloc.Control; mem* := alloc.Memory*
4678 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
4679 // Then initialize to zero the non-header parts of the raw memory block:
4680 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
4681 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
4682 // After the initialize node executes, the object is ready for service:
4683 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
4684 // Suppose its body is immediately initialized as {1,2}:
4685 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
4686 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
4687 // mem.SLICE(#short[*]) := store2
4688 //
4689 // DETAILS:
4690 // An InitializeNode collects and isolates object initialization after
4691 // an AllocateNode and before the next possible safepoint. As a
4692 // memory barrier (MemBarNode), it keeps critical stores from drifting
4693 // down past any safepoint or any publication of the allocation.
4694 // Before this barrier, a newly-allocated object may have uninitialized bits.
4695 // After this barrier, it may be treated as a real oop, and GC is allowed.
4696 //
4697 // The semantics of the InitializeNode include an implicit zeroing of
4698 // the new object from object header to the end of the object.
4699 // (The object header and end are determined by the AllocateNode.)
4700 //
4701 // Certain stores may be added as direct inputs to the InitializeNode.
4702 // These stores must update raw memory, and they must be to addresses
4703 // derived from the raw address produced by AllocateNode, and with
4704 // a constant offset. They must be ordered by increasing offset.
4705 // The first one is at in(RawStores), the last at in(req()-1).
4706 // Unlike most memory operations, they are not linked in a chain,
4707 // but are displayed in parallel as users of the rawmem output of
4708 // the allocation.
4709 //
4710 // (See comments in InitializeNode::capture_store, which continue
4711 // the example given above.)
4712 //
4713 // When the associated Allocate is macro-expanded, the InitializeNode
4714 // may be rewritten to optimize collected stores. A ClearArrayNode
4715 // may also be created at that point to represent any required zeroing.
4716 // The InitializeNode is then marked 'complete', prohibiting further
4717 // capturing of nearby memory operations.
4718 //
4719 // During macro-expansion, all captured initializations which store
4720 // constant values of 32 bits or smaller are coalesced (if advantageous)
4721 // into larger 'tiles' 32 or 64 bits. This allows an object to be
4722 // initialized in fewer memory operations. Memory words which are
4723 // covered by neither tiles nor non-constant stores are pre-zeroed
4724 // by explicit stores of zero. (The code shape happens to do all
4725 // zeroing first, then all other stores, with both sequences occurring
4726 // in order of ascending offsets.)
4727 //
4728 // Alternatively, code may be inserted between an AllocateNode and its
4729 // InitializeNode, to perform arbitrary initialization of the new object.
4730 // E.g., the object copying intrinsics insert complex data transfers here.
4731 // The initialization must then be marked as 'complete' disable the
4732 // built-in zeroing semantics and the collection of initializing stores.
4733 //
4734 // While an InitializeNode is incomplete, reads from the memory state
4735 // produced by it are optimizable if they match the control edge and
4736 // new oop address associated with the allocation/initialization.
4737 // They return a stored value (if the offset matches) or else zero.
4738 // A write to the memory state, if it matches control and address,
4739 // and if it is to a constant offset, may be 'captured' by the
4740 // InitializeNode. It is cloned as a raw memory operation and rewired
4741 // inside the initialization, to the raw oop produced by the allocation.
4742 // Operations on addresses which are provably distinct (e.g., to
4743 // other AllocateNodes) are allowed to bypass the initialization.
4744 //
4745 // The effect of all this is to consolidate object initialization
4746 // (both arrays and non-arrays, both piecewise and bulk) into a
4747 // single location, where it can be optimized as a unit.
4748 //
4749 // Only stores with an offset less than TrackedInitializationLimit words
4750 // will be considered for capture by an InitializeNode. This puts a
4751 // reasonable limit on the complexity of optimized initializations.
4752
4753 //---------------------------InitializeNode------------------------------------
4754 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
4755 : MemBarNode(C, adr_type, rawoop),
4756 _is_complete(Incomplete), _does_not_escape(false)
4757 {
4758 init_class_id(Class_Initialize);
4759
4760 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
4761 assert(in(RawAddress) == rawoop, "proper init");
4762 // Note: allocation() can be null, for secondary initialization barriers
4763 }
4764
4765 // Since this node is not matched, it will be processed by the
4766 // register allocator. Declare that there are no constraints
4767 // on the allocation of the RawAddress edge.
4768 const RegMask &InitializeNode::in_RegMask(uint idx) const {
4769 // This edge should be set to top, by the set_complete. But be conservative.
4770 if (idx == InitializeNode::RawAddress)
4771 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
4772 return RegMask::EMPTY;
4773 }
4774
4775 Node* InitializeNode::memory(uint alias_idx) {
4776 Node* mem = in(Memory);
4777 if (mem->is_MergeMem()) {
4778 return mem->as_MergeMem()->memory_at(alias_idx);
4779 } else {
4780 // incoming raw memory is not split
4781 return mem;
4782 }
4783 }
4784
4785 bool InitializeNode::is_non_zero() {
4786 if (is_complete()) return false;
4787 remove_extra_zeroes();
4788 return (req() > RawStores);
4789 }
4790
4791 void InitializeNode::set_complete(PhaseGVN* phase) {
4792 assert(!is_complete(), "caller responsibility");
4793 _is_complete = Complete;
4794
4795 // After this node is complete, it contains a bunch of
4796 // raw-memory initializations. There is no need for
4797 // it to have anything to do with non-raw memory effects.
4798 // Therefore, tell all non-raw users to re-optimize themselves,
4799 // after skipping the memory effects of this initialization.
4800 PhaseIterGVN* igvn = phase->is_IterGVN();
4801 if (igvn) igvn->add_users_to_worklist(this);
4802 }
4803
4804 // convenience function
4805 // return false if the init contains any stores already
4806 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
4807 InitializeNode* init = initialization();
4808 if (init == nullptr || init->is_complete()) return false;
4809 init->remove_extra_zeroes();
4810 // for now, if this allocation has already collected any inits, bail:
4811 if (init->is_non_zero()) return false;
4812 init->set_complete(phase);
4813 return true;
4814 }
4815
4816 void InitializeNode::remove_extra_zeroes() {
4817 if (req() == RawStores) return;
4818 Node* zmem = zero_memory();
4819 uint fill = RawStores;
4820 for (uint i = fill; i < req(); i++) {
4821 Node* n = in(i);
4822 if (n->is_top() || n == zmem) continue; // skip
4823 if (fill < i) set_req(fill, n); // compact
4824 ++fill;
4825 }
4826 // delete any empty spaces created:
4827 while (fill < req()) {
4828 del_req(fill);
4829 }
4830 }
4831
4832 // Helper for remembering which stores go with which offsets.
4833 intptr_t InitializeNode::get_store_offset(Node* st, PhaseValues* phase) {
4834 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
4835 intptr_t offset = -1;
4836 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
4837 phase, offset);
4838 if (base == nullptr) return -1; // something is dead,
4839 if (offset < 0) return -1; // dead, dead
4840 return offset;
4841 }
4842
4843 // Helper for proving that an initialization expression is
4844 // "simple enough" to be folded into an object initialization.
4845 // Attempts to prove that a store's initial value 'n' can be captured
4846 // within the initialization without creating a vicious cycle, such as:
4847 // { Foo p = new Foo(); p.next = p; }
4848 // True for constants and parameters and small combinations thereof.
4849 bool InitializeNode::detect_init_independence(Node* value, PhaseGVN* phase) {
4850 ResourceMark rm;
4851 Unique_Node_List worklist;
4852 worklist.push(value);
4853
4854 uint complexity_limit = 20;
4855 for (uint j = 0; j < worklist.size(); j++) {
4856 if (j >= complexity_limit) {
4857 return false; // Bail out if processed too many nodes
4858 }
4859
4860 Node* n = worklist.at(j);
4861 if (n == nullptr) continue; // (can this really happen?)
4862 if (n->is_Proj()) n = n->in(0);
4863 if (n == this) return false; // found a cycle
4864 if (n->is_Con()) continue;
4865 if (n->is_Start()) continue; // params, etc., are OK
4866 if (n->is_Root()) continue; // even better
4867
4868 // There cannot be any dependency if 'n' is a CFG node that dominates the current allocation
4869 if (n->is_CFG() && phase->is_dominator(n, allocation())) {
4870 continue;
4871 }
4872
4873 Node* ctl = n->in(0);
4874 if (ctl != nullptr && !ctl->is_top()) {
4875 if (ctl->is_Proj()) ctl = ctl->in(0);
4876 if (ctl == this) return false;
4877
4878 // If we already know that the enclosing memory op is pinned right after
4879 // the init, then any control flow that the store has picked up
4880 // must have preceded the init, or else be equal to the init.
4881 // Even after loop optimizations (which might change control edges)
4882 // a store is never pinned *before* the availability of its inputs.
4883 if (!MemNode::all_controls_dominate(n, this, phase)) {
4884 return false; // failed to prove a good control
4885 }
4886 }
4887
4888 // Check data edges for possible dependencies on 'this'.
4889 for (uint i = 1; i < n->req(); i++) {
4890 Node* m = n->in(i);
4891 if (m == nullptr || m == n || m->is_top()) continue;
4892
4893 // Only process data inputs once
4894 worklist.push(m);
4895 }
4896 }
4897
4898 return true;
4899 }
4900
4901 // Here are all the checks a Store must pass before it can be moved into
4902 // an initialization. Returns zero if a check fails.
4903 // On success, returns the (constant) offset to which the store applies,
4904 // within the initialized memory.
4905 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseGVN* phase, bool can_reshape) {
4906 const int FAIL = 0;
4907 if (st->req() != MemNode::ValueIn + 1)
4908 return FAIL; // an inscrutable StoreNode (card mark?)
4909 Node* ctl = st->in(MemNode::Control);
4910 if (!(ctl != nullptr && ctl->is_Proj() && ctl->in(0) == this))
4911 return FAIL; // must be unconditional after the initialization
4912 Node* mem = st->in(MemNode::Memory);
4913 if (!(mem->is_Proj() && mem->in(0) == this))
4914 return FAIL; // must not be preceded by other stores
4915 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
4916 if ((st->Opcode() == Op_StoreP || st->Opcode() == Op_StoreN) &&
4917 !bs->can_initialize_object(st)) {
4918 return FAIL;
4919 }
4920 Node* adr = st->in(MemNode::Address);
4921 intptr_t offset;
4922 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
4923 if (alloc == nullptr)
4924 return FAIL; // inscrutable address
4925 if (alloc != allocation())
4926 return FAIL; // wrong allocation! (store needs to float up)
4927 int size_in_bytes = st->memory_size();
4928 if ((size_in_bytes != 0) && (offset % size_in_bytes) != 0) {
4929 return FAIL; // mismatched access
4930 }
4931 Node* val = st->in(MemNode::ValueIn);
4932
4933 if (!detect_init_independence(val, phase))
4934 return FAIL; // stored value must be 'simple enough'
4935
4936 // The Store can be captured only if nothing after the allocation
4937 // and before the Store is using the memory location that the store
4938 // overwrites.
4939 bool failed = false;
4940 // If is_complete_with_arraycopy() is true the shape of the graph is
4941 // well defined and is safe so no need for extra checks.
4942 if (!is_complete_with_arraycopy()) {
4943 // We are going to look at each use of the memory state following
4944 // the allocation to make sure nothing reads the memory that the
4945 // Store writes.
4946 const TypePtr* t_adr = phase->type(adr)->isa_ptr();
4947 int alias_idx = phase->C->get_alias_index(t_adr);
4948 ResourceMark rm;
4949 Unique_Node_List mems;
4950 mems.push(mem);
4951 Node* unique_merge = nullptr;
4952 for (uint next = 0; next < mems.size(); ++next) {
4953 Node *m = mems.at(next);
4954 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
4955 Node *n = m->fast_out(j);
4956 if (n->outcnt() == 0) {
4957 continue;
4958 }
4959 if (n == st) {
4960 continue;
4961 } else if (n->in(0) != nullptr && n->in(0) != ctl) {
4962 // If the control of this use is different from the control
4963 // of the Store which is right after the InitializeNode then
4964 // this node cannot be between the InitializeNode and the
4965 // Store.
4966 continue;
4967 } else if (n->is_MergeMem()) {
4968 if (n->as_MergeMem()->memory_at(alias_idx) == m) {
4969 // We can hit a MergeMemNode (that will likely go away
4970 // later) that is a direct use of the memory state
4971 // following the InitializeNode on the same slice as the
4972 // store node that we'd like to capture. We need to check
4973 // the uses of the MergeMemNode.
4974 mems.push(n);
4975 }
4976 } else if (n->is_Mem()) {
4977 Node* other_adr = n->in(MemNode::Address);
4978 if (other_adr == adr) {
4979 failed = true;
4980 break;
4981 } else {
4982 const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr();
4983 if (other_t_adr != nullptr) {
4984 int other_alias_idx = phase->C->get_alias_index(other_t_adr);
4985 if (other_alias_idx == alias_idx) {
4986 // A load from the same memory slice as the store right
4987 // after the InitializeNode. We check the control of the
4988 // object/array that is loaded from. If it's the same as
4989 // the store control then we cannot capture the store.
4990 assert(!n->is_Store(), "2 stores to same slice on same control?");
4991 Node* base = other_adr;
4992 assert(base->is_AddP(), "should be addp but is %s", base->Name());
4993 base = base->in(AddPNode::Base);
4994 if (base != nullptr) {
4995 base = base->uncast();
4996 if (base->is_Proj() && base->in(0) == alloc) {
4997 failed = true;
4998 break;
4999 }
5000 }
5001 }
5002 }
5003 }
5004 } else {
5005 failed = true;
5006 break;
5007 }
5008 }
5009 }
5010 }
5011 if (failed) {
5012 if (!can_reshape) {
5013 // We decided we couldn't capture the store during parsing. We
5014 // should try again during the next IGVN once the graph is
5015 // cleaner.
5016 phase->C->record_for_igvn(st);
5017 }
5018 return FAIL;
5019 }
5020
5021 return offset; // success
5022 }
5023
5024 // Find the captured store in(i) which corresponds to the range
5025 // [start..start+size) in the initialized object.
5026 // If there is one, return its index i. If there isn't, return the
5027 // negative of the index where it should be inserted.
5028 // Return 0 if the queried range overlaps an initialization boundary
5029 // or if dead code is encountered.
5030 // If size_in_bytes is zero, do not bother with overlap checks.
5031 int InitializeNode::captured_store_insertion_point(intptr_t start,
5032 int size_in_bytes,
5033 PhaseValues* phase) {
5034 const int FAIL = 0, MAX_STORE = MAX2(BytesPerLong, (int)MaxVectorSize);
5035
5036 if (is_complete())
5037 return FAIL; // arraycopy got here first; punt
5038
5039 assert(allocation() != nullptr, "must be present");
5040
5041 // no negatives, no header fields:
5042 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
5043
5044 // after a certain size, we bail out on tracking all the stores:
5045 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
5046 if (start >= ti_limit) return FAIL;
5047
5048 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
5049 if (i >= limit) return -(int)i; // not found; here is where to put it
5050
5051 Node* st = in(i);
5052 intptr_t st_off = get_store_offset(st, phase);
5053 if (st_off < 0) {
5054 if (st != zero_memory()) {
5055 return FAIL; // bail out if there is dead garbage
5056 }
5057 } else if (st_off > start) {
5058 // ...we are done, since stores are ordered
5059 if (st_off < start + size_in_bytes) {
5060 return FAIL; // the next store overlaps
5061 }
5062 return -(int)i; // not found; here is where to put it
5063 } else if (st_off < start) {
5064 assert(st->as_Store()->memory_size() <= MAX_STORE, "");
5065 if (size_in_bytes != 0 &&
5066 start < st_off + MAX_STORE &&
5067 start < st_off + st->as_Store()->memory_size()) {
5068 return FAIL; // the previous store overlaps
5069 }
5070 } else {
5071 if (size_in_bytes != 0 &&
5072 st->as_Store()->memory_size() != size_in_bytes) {
5073 return FAIL; // mismatched store size
5074 }
5075 return i;
5076 }
5077
5078 ++i;
5079 }
5080 }
5081
5082 // Look for a captured store which initializes at the offset 'start'
5083 // with the given size. If there is no such store, and no other
5084 // initialization interferes, then return zero_memory (the memory
5085 // projection of the AllocateNode).
5086 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
5087 PhaseValues* phase) {
5088 assert(stores_are_sane(phase), "");
5089 int i = captured_store_insertion_point(start, size_in_bytes, phase);
5090 if (i == 0) {
5091 return nullptr; // something is dead
5092 } else if (i < 0) {
5093 return zero_memory(); // just primordial zero bits here
5094 } else {
5095 Node* st = in(i); // here is the store at this position
5096 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
5097 return st;
5098 }
5099 }
5100
5101 // Create, as a raw pointer, an address within my new object at 'offset'.
5102 Node* InitializeNode::make_raw_address(intptr_t offset,
5103 PhaseGVN* phase) {
5104 Node* addr = in(RawAddress);
5105 if (offset != 0) {
5106 Compile* C = phase->C;
5107 addr = phase->transform(AddPNode::make_off_heap(addr, phase->MakeConX(offset)));
5108 }
5109 return addr;
5110 }
5111
5112 // Clone the given store, converting it into a raw store
5113 // initializing a field or element of my new object.
5114 // Caller is responsible for retiring the original store,
5115 // with subsume_node or the like.
5116 //
5117 // From the example above InitializeNode::InitializeNode,
5118 // here are the old stores to be captured:
5119 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
5120 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
5121 //
5122 // Here is the changed code; note the extra edges on init:
5123 // alloc = (Allocate ...)
5124 // rawoop = alloc.RawAddress
5125 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
5126 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
5127 // init = (Initialize alloc.Control alloc.Memory rawoop
5128 // rawstore1 rawstore2)
5129 //
5130 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
5131 PhaseGVN* phase, bool can_reshape) {
5132 assert(stores_are_sane(phase), "");
5133
5134 if (start < 0) return nullptr;
5135 assert(can_capture_store(st, phase, can_reshape) == start, "sanity");
5136
5137 Compile* C = phase->C;
5138 int size_in_bytes = st->memory_size();
5139 int i = captured_store_insertion_point(start, size_in_bytes, phase);
5140 if (i == 0) return nullptr; // bail out
5141 Node* prev_mem = nullptr; // raw memory for the captured store
5142 if (i > 0) {
5143 prev_mem = in(i); // there is a pre-existing store under this one
5144 set_req(i, C->top()); // temporarily disconnect it
5145 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
5146 } else {
5147 i = -i; // no pre-existing store
5148 prev_mem = zero_memory(); // a slice of the newly allocated object
5149 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
5150 set_req(--i, C->top()); // reuse this edge; it has been folded away
5151 else
5152 ins_req(i, C->top()); // build a new edge
5153 }
5154 Node* new_st = st->clone_with_adr_type(TypeRawPtr::BOTTOM);
5155 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
5156 new_st->set_req(MemNode::Control, in(Control));
5157 new_st->set_req(MemNode::Memory, prev_mem);
5158 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
5159 bs->eliminate_gc_barrier_data(new_st);
5160 new_st = phase->transform(new_st);
5161
5162 // At this point, new_st might have swallowed a pre-existing store
5163 // at the same offset, or perhaps new_st might have disappeared,
5164 // if it redundantly stored the same value (or zero to fresh memory).
5165
5166 // In any case, wire it in:
5167 PhaseIterGVN* igvn = phase->is_IterGVN();
5168 if (igvn) {
5169 igvn->rehash_node_delayed(this);
5170 }
5171 set_req(i, new_st);
5172
5173 // The caller may now kill the old guy.
5174 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
5175 assert(check_st == new_st || check_st == nullptr, "must be findable");
5176 assert(!is_complete(), "");
5177 return new_st;
5178 }
5179
5180 static bool store_constant(jlong* tiles, int num_tiles,
5181 intptr_t st_off, int st_size,
5182 jlong con) {
5183 if ((st_off & (st_size-1)) != 0)
5184 return false; // strange store offset (assume size==2**N)
5185 address addr = (address)tiles + st_off;
5186 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
5187 switch (st_size) {
5188 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
5189 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
5190 case sizeof(jint): *(jint*) addr = (jint) con; break;
5191 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
5192 default: return false; // strange store size (detect size!=2**N here)
5193 }
5194 return true; // return success to caller
5195 }
5196
5197 // Coalesce subword constants into int constants and possibly
5198 // into long constants. The goal, if the CPU permits,
5199 // is to initialize the object with a small number of 64-bit tiles.
5200 // Also, convert floating-point constants to bit patterns.
5201 // Non-constants are not relevant to this pass.
5202 //
5203 // In terms of the running example on InitializeNode::InitializeNode
5204 // and InitializeNode::capture_store, here is the transformation
5205 // of rawstore1 and rawstore2 into rawstore12:
5206 // alloc = (Allocate ...)
5207 // rawoop = alloc.RawAddress
5208 // tile12 = 0x00010002
5209 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
5210 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
5211 //
5212 void
5213 InitializeNode::coalesce_subword_stores(intptr_t header_size,
5214 Node* size_in_bytes,
5215 PhaseGVN* phase) {
5216 Compile* C = phase->C;
5217
5218 assert(stores_are_sane(phase), "");
5219 // Note: After this pass, they are not completely sane,
5220 // since there may be some overlaps.
5221
5222 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
5223
5224 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
5225 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
5226 size_limit = MIN2(size_limit, ti_limit);
5227 size_limit = align_up(size_limit, BytesPerLong);
5228 int num_tiles = size_limit / BytesPerLong;
5229
5230 // allocate space for the tile map:
5231 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
5232 jlong tiles_buf[small_len];
5233 Node* nodes_buf[small_len];
5234 jlong inits_buf[small_len];
5235 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
5236 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
5237 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
5238 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
5239 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
5240 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
5241 // tiles: exact bitwise model of all primitive constants
5242 // nodes: last constant-storing node subsumed into the tiles model
5243 // inits: which bytes (in each tile) are touched by any initializations
5244
5245 //// Pass A: Fill in the tile model with any relevant stores.
5246
5247 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
5248 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
5249 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
5250 Node* zmem = zero_memory(); // initially zero memory state
5251 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
5252 Node* st = in(i);
5253 intptr_t st_off = get_store_offset(st, phase);
5254
5255 // Figure out the store's offset and constant value:
5256 if (st_off < header_size) continue; //skip (ignore header)
5257 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
5258 int st_size = st->as_Store()->memory_size();
5259 if (st_off + st_size > size_limit) break;
5260
5261 // Record which bytes are touched, whether by constant or not.
5262 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
5263 continue; // skip (strange store size)
5264
5265 const Type* val = phase->type(st->in(MemNode::ValueIn));
5266 if (!val->singleton()) continue; //skip (non-con store)
5267 BasicType type = val->basic_type();
5268
5269 jlong con = 0;
5270 switch (type) {
5271 case T_INT: con = val->is_int()->get_con(); break;
5272 case T_LONG: con = val->is_long()->get_con(); break;
5273 case T_FLOAT: con = jint_cast(val->getf()); break;
5274 case T_DOUBLE: con = jlong_cast(val->getd()); break;
5275 default: continue; //skip (odd store type)
5276 }
5277
5278 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
5279 st->Opcode() == Op_StoreL) {
5280 continue; // This StoreL is already optimal.
5281 }
5282
5283 // Store down the constant.
5284 store_constant(tiles, num_tiles, st_off, st_size, con);
5285
5286 intptr_t j = st_off >> LogBytesPerLong;
5287
5288 if (type == T_INT && st_size == BytesPerInt
5289 && (st_off & BytesPerInt) == BytesPerInt) {
5290 jlong lcon = tiles[j];
5291 if (!Matcher::isSimpleConstant64(lcon) &&
5292 st->Opcode() == Op_StoreI) {
5293 // This StoreI is already optimal by itself.
5294 jint* intcon = (jint*) &tiles[j];
5295 intcon[1] = 0; // undo the store_constant()
5296
5297 // If the previous store is also optimal by itself, back up and
5298 // undo the action of the previous loop iteration... if we can.
5299 // But if we can't, just let the previous half take care of itself.
5300 st = nodes[j];
5301 st_off -= BytesPerInt;
5302 con = intcon[0];
5303 if (con != 0 && st != nullptr && st->Opcode() == Op_StoreI) {
5304 assert(st_off >= header_size, "still ignoring header");
5305 assert(get_store_offset(st, phase) == st_off, "must be");
5306 assert(in(i-1) == zmem, "must be");
5307 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
5308 assert(con == tcon->is_int()->get_con(), "must be");
5309 // Undo the effects of the previous loop trip, which swallowed st:
5310 intcon[0] = 0; // undo store_constant()
5311 set_req(i-1, st); // undo set_req(i, zmem)
5312 nodes[j] = nullptr; // undo nodes[j] = st
5313 --old_subword; // undo ++old_subword
5314 }
5315 continue; // This StoreI is already optimal.
5316 }
5317 }
5318
5319 // This store is not needed.
5320 set_req(i, zmem);
5321 nodes[j] = st; // record for the moment
5322 if (st_size < BytesPerLong) // something has changed
5323 ++old_subword; // includes int/float, but who's counting...
5324 else ++old_long;
5325 }
5326
5327 if ((old_subword + old_long) == 0)
5328 return; // nothing more to do
5329
5330 //// Pass B: Convert any non-zero tiles into optimal constant stores.
5331 // Be sure to insert them before overlapping non-constant stores.
5332 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
5333 for (int j = 0; j < num_tiles; j++) {
5334 jlong con = tiles[j];
5335 jlong init = inits[j];
5336 if (con == 0) continue;
5337 jint con0, con1; // split the constant, address-wise
5338 jint init0, init1; // split the init map, address-wise
5339 { union { jlong con; jint intcon[2]; } u;
5340 u.con = con;
5341 con0 = u.intcon[0];
5342 con1 = u.intcon[1];
5343 u.con = init;
5344 init0 = u.intcon[0];
5345 init1 = u.intcon[1];
5346 }
5347
5348 Node* old = nodes[j];
5349 assert(old != nullptr, "need the prior store");
5350 intptr_t offset = (j * BytesPerLong);
5351
5352 bool split = !Matcher::isSimpleConstant64(con);
5353
5354 if (offset < header_size) {
5355 assert(offset + BytesPerInt >= header_size, "second int counts");
5356 assert(*(jint*)&tiles[j] == 0, "junk in header");
5357 split = true; // only the second word counts
5358 // Example: int a[] = { 42 ... }
5359 } else if (con0 == 0 && init0 == -1) {
5360 split = true; // first word is covered by full inits
5361 // Example: int a[] = { ... foo(), 42 ... }
5362 } else if (con1 == 0 && init1 == -1) {
5363 split = true; // second word is covered by full inits
5364 // Example: int a[] = { ... 42, foo() ... }
5365 }
5366
5367 // Here's a case where init0 is neither 0 nor -1:
5368 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
5369 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
5370 // In this case the tile is not split; it is (jlong)42.
5371 // The big tile is stored down, and then the foo() value is inserted.
5372 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
5373
5374 Node* ctl = old->in(MemNode::Control);
5375 Node* adr = make_raw_address(offset, phase);
5376 const TypePtr* atp = TypeRawPtr::BOTTOM;
5377
5378 // One or two coalesced stores to plop down.
5379 Node* st[2];
5380 intptr_t off[2];
5381 int nst = 0;
5382 if (!split) {
5383 ++new_long;
5384 off[nst] = offset;
5385 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
5386 phase->longcon(con), T_LONG, MemNode::unordered);
5387 } else {
5388 // Omit either if it is a zero.
5389 if (con0 != 0) {
5390 ++new_int;
5391 off[nst] = offset;
5392 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
5393 phase->intcon(con0), T_INT, MemNode::unordered);
5394 }
5395 if (con1 != 0) {
5396 ++new_int;
5397 offset += BytesPerInt;
5398 adr = make_raw_address(offset, phase);
5399 off[nst] = offset;
5400 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
5401 phase->intcon(con1), T_INT, MemNode::unordered);
5402 }
5403 }
5404
5405 // Insert second store first, then the first before the second.
5406 // Insert each one just before any overlapping non-constant stores.
5407 while (nst > 0) {
5408 Node* st1 = st[--nst];
5409 C->copy_node_notes_to(st1, old);
5410 st1 = phase->transform(st1);
5411 offset = off[nst];
5412 assert(offset >= header_size, "do not smash header");
5413 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
5414 guarantee(ins_idx != 0, "must re-insert constant store");
5415 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
5416 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
5417 set_req(--ins_idx, st1);
5418 else
5419 ins_req(ins_idx, st1);
5420 }
5421 }
5422
5423 if (PrintCompilation && WizardMode)
5424 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
5425 old_subword, old_long, new_int, new_long);
5426 if (C->log() != nullptr)
5427 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
5428 old_subword, old_long, new_int, new_long);
5429
5430 // Clean up any remaining occurrences of zmem:
5431 remove_extra_zeroes();
5432 }
5433
5434 // Explore forward from in(start) to find the first fully initialized
5435 // word, and return its offset. Skip groups of subword stores which
5436 // together initialize full words. If in(start) is itself part of a
5437 // fully initialized word, return the offset of in(start). If there
5438 // are no following full-word stores, or if something is fishy, return
5439 // a negative value.
5440 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
5441 int int_map = 0;
5442 intptr_t int_map_off = 0;
5443 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
5444
5445 for (uint i = start, limit = req(); i < limit; i++) {
5446 Node* st = in(i);
5447
5448 intptr_t st_off = get_store_offset(st, phase);
5449 if (st_off < 0) break; // return conservative answer
5450
5451 int st_size = st->as_Store()->memory_size();
5452 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
5453 return st_off; // we found a complete word init
5454 }
5455
5456 // update the map:
5457
5458 intptr_t this_int_off = align_down(st_off, BytesPerInt);
5459 if (this_int_off != int_map_off) {
5460 // reset the map:
5461 int_map = 0;
5462 int_map_off = this_int_off;
5463 }
5464
5465 int subword_off = st_off - this_int_off;
5466 int_map |= right_n_bits(st_size) << subword_off;
5467 if ((int_map & FULL_MAP) == FULL_MAP) {
5468 return this_int_off; // we found a complete word init
5469 }
5470
5471 // Did this store hit or cross the word boundary?
5472 intptr_t next_int_off = align_down(st_off + st_size, BytesPerInt);
5473 if (next_int_off == this_int_off + BytesPerInt) {
5474 // We passed the current int, without fully initializing it.
5475 int_map_off = next_int_off;
5476 int_map >>= BytesPerInt;
5477 } else if (next_int_off > this_int_off + BytesPerInt) {
5478 // We passed the current and next int.
5479 return this_int_off + BytesPerInt;
5480 }
5481 }
5482
5483 return -1;
5484 }
5485
5486
5487 // Called when the associated AllocateNode is expanded into CFG.
5488 // At this point, we may perform additional optimizations.
5489 // Linearize the stores by ascending offset, to make memory
5490 // activity as coherent as possible.
5491 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
5492 intptr_t header_size,
5493 Node* size_in_bytes,
5494 PhaseIterGVN* phase) {
5495 assert(!is_complete(), "not already complete");
5496 assert(stores_are_sane(phase), "");
5497 assert(allocation() != nullptr, "must be present");
5498
5499 remove_extra_zeroes();
5500
5501 if (ReduceFieldZeroing || ReduceBulkZeroing)
5502 // reduce instruction count for common initialization patterns
5503 coalesce_subword_stores(header_size, size_in_bytes, phase);
5504
5505 Node* zmem = zero_memory(); // initially zero memory state
5506 Node* inits = zmem; // accumulating a linearized chain of inits
5507 #ifdef ASSERT
5508 intptr_t first_offset = allocation()->minimum_header_size();
5509 intptr_t last_init_off = first_offset; // previous init offset
5510 intptr_t last_init_end = first_offset; // previous init offset+size
5511 intptr_t last_tile_end = first_offset; // previous tile offset+size
5512 #endif
5513 intptr_t zeroes_done = header_size;
5514
5515 bool do_zeroing = true; // we might give up if inits are very sparse
5516 int big_init_gaps = 0; // how many large gaps have we seen?
5517
5518 if (UseTLAB && ZeroTLAB) do_zeroing = false;
5519 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
5520
5521 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
5522 Node* st = in(i);
5523 intptr_t st_off = get_store_offset(st, phase);
5524 if (st_off < 0)
5525 break; // unknown junk in the inits
5526 if (st->in(MemNode::Memory) != zmem)
5527 break; // complicated store chains somehow in list
5528
5529 int st_size = st->as_Store()->memory_size();
5530 intptr_t next_init_off = st_off + st_size;
5531
5532 if (do_zeroing && zeroes_done < next_init_off) {
5533 // See if this store needs a zero before it or under it.
5534 intptr_t zeroes_needed = st_off;
5535
5536 if (st_size < BytesPerInt) {
5537 // Look for subword stores which only partially initialize words.
5538 // If we find some, we must lay down some word-level zeroes first,
5539 // underneath the subword stores.
5540 //
5541 // Examples:
5542 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
5543 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
5544 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
5545 //
5546 // Note: coalesce_subword_stores may have already done this,
5547 // if it was prompted by constant non-zero subword initializers.
5548 // But this case can still arise with non-constant stores.
5549
5550 intptr_t next_full_store = find_next_fullword_store(i, phase);
5551
5552 // In the examples above:
5553 // in(i) p q r s x y z
5554 // st_off 12 13 14 15 12 13 14
5555 // st_size 1 1 1 1 1 1 1
5556 // next_full_s. 12 16 16 16 16 16 16
5557 // z's_done 12 16 16 16 12 16 12
5558 // z's_needed 12 16 16 16 16 16 16
5559 // zsize 0 0 0 0 4 0 4
5560 if (next_full_store < 0) {
5561 // Conservative tack: Zero to end of current word.
5562 zeroes_needed = align_up(zeroes_needed, BytesPerInt);
5563 } else {
5564 // Zero to beginning of next fully initialized word.
5565 // Or, don't zero at all, if we are already in that word.
5566 assert(next_full_store >= zeroes_needed, "must go forward");
5567 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
5568 zeroes_needed = next_full_store;
5569 }
5570 }
5571
5572 if (zeroes_needed > zeroes_done) {
5573 intptr_t zsize = zeroes_needed - zeroes_done;
5574 // Do some incremental zeroing on rawmem, in parallel with inits.
5575 zeroes_done = align_down(zeroes_done, BytesPerInt);
5576 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
5577 zeroes_done, zeroes_needed,
5578 true,
5579 phase);
5580 zeroes_done = zeroes_needed;
5581 if (zsize > InitArrayShortSize && ++big_init_gaps > 2)
5582 do_zeroing = false; // leave the hole, next time
5583 }
5584 }
5585
5586 // Collect the store and move on:
5587 phase->replace_input_of(st, MemNode::Memory, inits);
5588 inits = st; // put it on the linearized chain
5589 set_req(i, zmem); // unhook from previous position
5590
5591 if (zeroes_done == st_off)
5592 zeroes_done = next_init_off;
5593
5594 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
5595
5596 #ifdef ASSERT
5597 // Various order invariants. Weaker than stores_are_sane because
5598 // a large constant tile can be filled in by smaller non-constant stores.
5599 assert(st_off >= last_init_off, "inits do not reverse");
5600 last_init_off = st_off;
5601 const Type* val = nullptr;
5602 if (st_size >= BytesPerInt &&
5603 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
5604 (int)val->basic_type() < (int)T_OBJECT) {
5605 assert(st_off >= last_tile_end, "tiles do not overlap");
5606 assert(st_off >= last_init_end, "tiles do not overwrite inits");
5607 last_tile_end = MAX2(last_tile_end, next_init_off);
5608 } else {
5609 intptr_t st_tile_end = align_up(next_init_off, BytesPerLong);
5610 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
5611 assert(st_off >= last_init_end, "inits do not overlap");
5612 last_init_end = next_init_off; // it's a non-tile
5613 }
5614 #endif //ASSERT
5615 }
5616
5617 remove_extra_zeroes(); // clear out all the zmems left over
5618 add_req(inits);
5619
5620 if (!(UseTLAB && ZeroTLAB)) {
5621 // If anything remains to be zeroed, zero it all now.
5622 zeroes_done = align_down(zeroes_done, BytesPerInt);
5623 // if it is the last unused 4 bytes of an instance, forget about it
5624 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
5625 if (zeroes_done + BytesPerLong >= size_limit) {
5626 AllocateNode* alloc = allocation();
5627 assert(alloc != nullptr, "must be present");
5628 if (alloc != nullptr && alloc->Opcode() == Op_Allocate) {
5629 Node* klass_node = alloc->in(AllocateNode::KlassNode);
5630 ciKlass* k = phase->type(klass_node)->is_instklassptr()->instance_klass();
5631 if (zeroes_done == k->layout_helper())
5632 zeroes_done = size_limit;
5633 }
5634 }
5635 if (zeroes_done < size_limit) {
5636 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
5637 zeroes_done, size_in_bytes, true, phase);
5638 }
5639 }
5640
5641 set_complete(phase);
5642 return rawmem;
5643 }
5644
5645 void InitializeNode::replace_mem_projs_by(Node* mem, Compile* C) {
5646 auto replace_proj = [&](ProjNode* proj) {
5647 C->gvn_replace_by(proj, mem);
5648 return CONTINUE;
5649 };
5650 apply_to_projs(replace_proj, TypeFunc::Memory);
5651 }
5652
5653 void InitializeNode::replace_mem_projs_by(Node* mem, PhaseIterGVN* igvn) {
5654 DUIterator_Fast imax, i = fast_outs(imax);
5655 auto replace_proj = [&](ProjNode* proj) {
5656 igvn->replace_node(proj, mem);
5657 --i; --imax;
5658 return CONTINUE;
5659 };
5660 apply_to_projs(imax, i, replace_proj, TypeFunc::Memory);
5661 }
5662
5663 bool InitializeNode::already_has_narrow_mem_proj_with_adr_type(const TypePtr* adr_type) const {
5664 auto find_proj = [&](ProjNode* proj) {
5665 if (proj->adr_type() == adr_type) {
5666 return BREAK_AND_RETURN_CURRENT_PROJ;
5667 }
5668 return CONTINUE;
5669 };
5670 DUIterator_Fast imax, i = fast_outs(imax);
5671 return apply_to_narrow_mem_projs_any_iterator(UsesIteratorFast(imax, i, this), find_proj) != nullptr;
5672 }
5673
5674 MachProjNode* InitializeNode::mem_mach_proj() const {
5675 auto find_proj = [](ProjNode* proj) {
5676 if (proj->is_MachProj()) {
5677 return BREAK_AND_RETURN_CURRENT_PROJ;
5678 }
5679 return CONTINUE;
5680 };
5681 ProjNode* proj = apply_to_projs(find_proj, TypeFunc::Memory);
5682 if (proj == nullptr) {
5683 return nullptr;
5684 }
5685 return proj->as_MachProj();
5686 }
5687
5688 #ifdef ASSERT
5689 bool InitializeNode::stores_are_sane(PhaseValues* phase) {
5690 if (is_complete())
5691 return true; // stores could be anything at this point
5692 assert(allocation() != nullptr, "must be present");
5693 intptr_t last_off = allocation()->minimum_header_size();
5694 for (uint i = InitializeNode::RawStores; i < req(); i++) {
5695 Node* st = in(i);
5696 intptr_t st_off = get_store_offset(st, phase);
5697 if (st_off < 0) continue; // ignore dead garbage
5698 if (last_off > st_off) {
5699 tty->print_cr("*** bad store offset at %d: %zd > %zd", i, last_off, st_off);
5700 this->dump(2);
5701 assert(false, "ascending store offsets");
5702 return false;
5703 }
5704 last_off = st_off + st->as_Store()->memory_size();
5705 }
5706 return true;
5707 }
5708 #endif //ASSERT
5709
5710
5711
5712
5713 //============================MergeMemNode=====================================
5714 //
5715 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
5716 // contributing store or call operations. Each contributor provides the memory
5717 // state for a particular "alias type" (see Compile::alias_type). For example,
5718 // if a MergeMem has an input X for alias category #6, then any memory reference
5719 // to alias category #6 may use X as its memory state input, as an exact equivalent
5720 // to using the MergeMem as a whole.
5721 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
5722 //
5723 // (Here, the <N> notation gives the index of the relevant adr_type.)
5724 //
5725 // In one special case (and more cases in the future), alias categories overlap.
5726 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
5727 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
5728 // it is exactly equivalent to that state W:
5729 // MergeMem(<Bot>: W) <==> W
5730 //
5731 // Usually, the merge has more than one input. In that case, where inputs
5732 // overlap (i.e., one is Bot), the narrower alias type determines the memory
5733 // state for that type, and the wider alias type (Bot) fills in everywhere else:
5734 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
5735 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
5736 //
5737 // A merge can take a "wide" memory state as one of its narrow inputs.
5738 // This simply means that the merge observes out only the relevant parts of
5739 // the wide input. That is, wide memory states arriving at narrow merge inputs
5740 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
5741 //
5742 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
5743 // and that memory slices "leak through":
5744 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
5745 //
5746 // But, in such a cascade, repeated memory slices can "block the leak":
5747 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
5748 //
5749 // In the last example, Y is not part of the combined memory state of the
5750 // outermost MergeMem. The system must, of course, prevent unschedulable
5751 // memory states from arising, so you can be sure that the state Y is somehow
5752 // a precursor to state Y'.
5753 //
5754 //
5755 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
5756 // of each MergeMemNode array are exactly the numerical alias indexes, including
5757 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
5758 // Compile::alias_type (and kin) produce and manage these indexes.
5759 //
5760 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
5761 // (Note that this provides quick access to the top node inside MergeMem methods,
5762 // without the need to reach out via TLS to Compile::current.)
5763 //
5764 // As a consequence of what was just described, a MergeMem that represents a full
5765 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
5766 // containing all alias categories.
5767 //
5768 // MergeMem nodes never (?) have control inputs, so in(0) is null.
5769 //
5770 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
5771 // a memory state for the alias type <N>, or else the top node, meaning that
5772 // there is no particular input for that alias type. Note that the length of
5773 // a MergeMem is variable, and may be extended at any time to accommodate new
5774 // memory states at larger alias indexes. When merges grow, they are of course
5775 // filled with "top" in the unused in() positions.
5776 //
5777 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
5778 // (Top was chosen because it works smoothly with passes like GCM.)
5779 //
5780 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
5781 // the type of random VM bits like TLS references.) Since it is always the
5782 // first non-Bot memory slice, some low-level loops use it to initialize an
5783 // index variable: for (i = AliasIdxRaw; i < req(); i++).
5784 //
5785 //
5786 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
5787 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
5788 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
5789 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
5790 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
5791 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
5792 //
5793 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
5794 // really that different from the other memory inputs. An abbreviation called
5795 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
5796 //
5797 //
5798 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
5799 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
5800 // that "emerges though" the base memory will be marked as excluding the alias types
5801 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
5802 //
5803 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
5804 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
5805 //
5806 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
5807 // (It is currently unimplemented.) As you can see, the resulting merge is
5808 // actually a disjoint union of memory states, rather than an overlay.
5809 //
5810
5811 //------------------------------MergeMemNode-----------------------------------
5812 Node* MergeMemNode::make_empty_memory() {
5813 Node* empty_memory = (Node*) Compile::current()->top();
5814 assert(empty_memory->is_top(), "correct sentinel identity");
5815 return empty_memory;
5816 }
5817
5818 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
5819 init_class_id(Class_MergeMem);
5820 // all inputs are nullified in Node::Node(int)
5821 // set_input(0, nullptr); // no control input
5822
5823 // Initialize the edges uniformly to top, for starters.
5824 Node* empty_mem = make_empty_memory();
5825 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
5826 init_req(i,empty_mem);
5827 }
5828 assert(empty_memory() == empty_mem, "");
5829
5830 if( new_base != nullptr && new_base->is_MergeMem() ) {
5831 MergeMemNode* mdef = new_base->as_MergeMem();
5832 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
5833 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
5834 mms.set_memory(mms.memory2());
5835 }
5836 assert(base_memory() == mdef->base_memory(), "");
5837 } else {
5838 set_base_memory(new_base);
5839 }
5840 }
5841
5842 // Make a new, untransformed MergeMem with the same base as 'mem'.
5843 // If mem is itself a MergeMem, populate the result with the same edges.
5844 MergeMemNode* MergeMemNode::make(Node* mem) {
5845 return new MergeMemNode(mem);
5846 }
5847
5848 //------------------------------cmp--------------------------------------------
5849 uint MergeMemNode::hash() const { return NO_HASH; }
5850 bool MergeMemNode::cmp( const Node &n ) const {
5851 return (&n == this); // Always fail except on self
5852 }
5853
5854 //------------------------------Identity---------------------------------------
5855 Node* MergeMemNode::Identity(PhaseGVN* phase) {
5856 // Identity if this merge point does not record any interesting memory
5857 // disambiguations.
5858 Node* base_mem = base_memory();
5859 Node* empty_mem = empty_memory();
5860 if (base_mem != empty_mem) { // Memory path is not dead?
5861 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5862 Node* mem = in(i);
5863 if (mem != empty_mem && mem != base_mem) {
5864 return this; // Many memory splits; no change
5865 }
5866 }
5867 }
5868 return base_mem; // No memory splits; ID on the one true input
5869 }
5870
5871 //------------------------------Ideal------------------------------------------
5872 // This method is invoked recursively on chains of MergeMem nodes
5873 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
5874 // Remove chain'd MergeMems
5875 //
5876 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
5877 // relative to the "in(Bot)". Since we are patching both at the same time,
5878 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
5879 // but rewrite each "in(i)" relative to the new "in(Bot)".
5880 Node *progress = nullptr;
5881
5882
5883 Node* old_base = base_memory();
5884 Node* empty_mem = empty_memory();
5885 if (old_base == empty_mem)
5886 return nullptr; // Dead memory path.
5887
5888 MergeMemNode* old_mbase;
5889 if (old_base != nullptr && old_base->is_MergeMem())
5890 old_mbase = old_base->as_MergeMem();
5891 else
5892 old_mbase = nullptr;
5893 Node* new_base = old_base;
5894
5895 // simplify stacked MergeMems in base memory
5896 if (old_mbase) new_base = old_mbase->base_memory();
5897
5898 // the base memory might contribute new slices beyond my req()
5899 if (old_mbase) grow_to_match(old_mbase);
5900
5901 // Note: We do not call verify_sparse on entry, because inputs
5902 // can normalize to the base_memory via subsume_node or similar
5903 // mechanisms. This method repairs that damage.
5904
5905 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
5906
5907 // Look at each slice.
5908 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5909 Node* old_in = in(i);
5910 // calculate the old memory value
5911 Node* old_mem = old_in;
5912 if (old_mem == empty_mem) old_mem = old_base;
5913 assert(old_mem == memory_at(i), "");
5914
5915 // maybe update (reslice) the old memory value
5916
5917 // simplify stacked MergeMems
5918 Node* new_mem = old_mem;
5919 MergeMemNode* old_mmem;
5920 if (old_mem != nullptr && old_mem->is_MergeMem())
5921 old_mmem = old_mem->as_MergeMem();
5922 else
5923 old_mmem = nullptr;
5924 if (old_mmem == this) {
5925 // This can happen if loops break up and safepoints disappear.
5926 // A merge of BotPtr (default) with a RawPtr memory derived from a
5927 // safepoint can be rewritten to a merge of the same BotPtr with
5928 // the BotPtr phi coming into the loop. If that phi disappears
5929 // also, we can end up with a self-loop of the mergemem.
5930 // In general, if loops degenerate and memory effects disappear,
5931 // a mergemem can be left looking at itself. This simply means
5932 // that the mergemem's default should be used, since there is
5933 // no longer any apparent effect on this slice.
5934 // Note: If a memory slice is a MergeMem cycle, it is unreachable
5935 // from start. Update the input to TOP.
5936 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
5937 }
5938 else if (old_mmem != nullptr) {
5939 new_mem = old_mmem->memory_at(i);
5940 }
5941 // else preceding memory was not a MergeMem
5942
5943 // maybe store down a new value
5944 Node* new_in = new_mem;
5945 if (new_in == new_base) new_in = empty_mem;
5946
5947 if (new_in != old_in) {
5948 // Warning: Do not combine this "if" with the previous "if"
5949 // A memory slice might have be be rewritten even if it is semantically
5950 // unchanged, if the base_memory value has changed.
5951 set_req_X(i, new_in, phase);
5952 progress = this; // Report progress
5953 }
5954 }
5955
5956 if (new_base != old_base) {
5957 set_req_X(Compile::AliasIdxBot, new_base, phase);
5958 // Don't use set_base_memory(new_base), because we need to update du.
5959 assert(base_memory() == new_base, "");
5960 progress = this;
5961 }
5962
5963 if( base_memory() == this ) {
5964 // a self cycle indicates this memory path is dead
5965 set_req(Compile::AliasIdxBot, empty_mem);
5966 }
5967
5968 // Resolve external cycles by calling Ideal on a MergeMem base_memory
5969 // Recursion must occur after the self cycle check above
5970 if( base_memory()->is_MergeMem() ) {
5971 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
5972 Node *m = phase->transform(new_mbase); // Rollup any cycles
5973 if( m != nullptr &&
5974 (m->is_top() ||
5975 (m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem)) ) {
5976 // propagate rollup of dead cycle to self
5977 set_req(Compile::AliasIdxBot, empty_mem);
5978 }
5979 }
5980
5981 if( base_memory() == empty_mem ) {
5982 progress = this;
5983 // Cut inputs during Parse phase only.
5984 // During Optimize phase a dead MergeMem node will be subsumed by Top.
5985 if( !can_reshape ) {
5986 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5987 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
5988 }
5989 }
5990 }
5991
5992 if( !progress && base_memory()->is_Phi() && can_reshape ) {
5993 // Check if PhiNode::Ideal's "Split phis through memory merges"
5994 // transform should be attempted. Look for this->phi->this cycle.
5995 uint merge_width = req();
5996 if (merge_width > Compile::AliasIdxRaw) {
5997 PhiNode* phi = base_memory()->as_Phi();
5998 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
5999 if (phi->in(i) == this) {
6000 phase->is_IterGVN()->_worklist.push(phi);
6001 break;
6002 }
6003 }
6004 }
6005 }
6006
6007 assert(progress || verify_sparse(), "please, no dups of base");
6008 return progress;
6009 }
6010
6011 //-------------------------set_base_memory-------------------------------------
6012 void MergeMemNode::set_base_memory(Node *new_base) {
6013 Node* empty_mem = empty_memory();
6014 set_req(Compile::AliasIdxBot, new_base);
6015 assert(memory_at(req()) == new_base, "must set default memory");
6016 // Clear out other occurrences of new_base:
6017 if (new_base != empty_mem) {
6018 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
6019 if (in(i) == new_base) set_req(i, empty_mem);
6020 }
6021 }
6022 }
6023
6024 //------------------------------out_RegMask------------------------------------
6025 const RegMask &MergeMemNode::out_RegMask() const {
6026 return RegMask::EMPTY;
6027 }
6028
6029 //------------------------------dump_spec--------------------------------------
6030 #ifndef PRODUCT
6031 void MergeMemNode::dump_spec(outputStream *st) const {
6032 st->print(" {");
6033 Node* base_mem = base_memory();
6034 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
6035 Node* mem = (in(i) != nullptr) ? memory_at(i) : base_mem;
6036 if (mem == base_mem) { st->print(" -"); continue; }
6037 st->print( " N%d:", mem->_idx );
6038 Compile::current()->get_adr_type(i)->dump_on(st);
6039 }
6040 st->print(" }");
6041 }
6042 #endif // !PRODUCT
6043
6044
6045 #ifdef ASSERT
6046 static bool might_be_same(Node* a, Node* b) {
6047 if (a == b) return true;
6048 if (!(a->is_Phi() || b->is_Phi())) return false;
6049 // phis shift around during optimization
6050 return true; // pretty stupid...
6051 }
6052
6053 // verify a narrow slice (either incoming or outgoing)
6054 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
6055 if (!VerifyAliases) return; // don't bother to verify unless requested
6056 if (VMError::is_error_reported()) return; // muzzle asserts when debugging an error
6057 if (Node::in_dump()) return; // muzzle asserts when printing
6058 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
6059 assert(n != nullptr, "");
6060 // Elide intervening MergeMem's
6061 while (n->is_MergeMem()) {
6062 n = n->as_MergeMem()->memory_at(alias_idx);
6063 }
6064 Compile* C = Compile::current();
6065 const TypePtr* n_adr_type = n->adr_type();
6066 if (n == m->empty_memory()) {
6067 // Implicit copy of base_memory()
6068 } else if (n_adr_type != TypePtr::BOTTOM) {
6069 assert(n_adr_type != nullptr, "new memory must have a well-defined adr_type");
6070 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
6071 } else {
6072 // A few places like make_runtime_call "know" that VM calls are narrow,
6073 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
6074 bool expected_wide_mem = false;
6075 if (n == m->base_memory()) {
6076 expected_wide_mem = true;
6077 } else if (alias_idx == Compile::AliasIdxRaw ||
6078 n == m->memory_at(Compile::AliasIdxRaw)) {
6079 expected_wide_mem = true;
6080 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
6081 // memory can "leak through" calls on channels that
6082 // are write-once. Allow this also.
6083 expected_wide_mem = true;
6084 }
6085 assert(expected_wide_mem, "expected narrow slice replacement");
6086 }
6087 }
6088 #else // !ASSERT
6089 #define verify_memory_slice(m,i,n) (void)(0) // PRODUCT version is no-op
6090 #endif
6091
6092
6093 //-----------------------------memory_at---------------------------------------
6094 Node* MergeMemNode::memory_at(uint alias_idx) const {
6095 assert(alias_idx >= Compile::AliasIdxRaw ||
6096 (alias_idx == Compile::AliasIdxBot && !Compile::current()->do_aliasing()),
6097 "must avoid base_memory and AliasIdxTop");
6098
6099 // Otherwise, it is a narrow slice.
6100 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
6101 if (is_empty_memory(n)) {
6102 // the array is sparse; empty slots are the "top" node
6103 n = base_memory();
6104 assert(Node::in_dump()
6105 || n == nullptr || n->bottom_type() == Type::TOP
6106 || n->adr_type() == nullptr // address is TOP
6107 || n->adr_type() == TypePtr::BOTTOM
6108 || n->adr_type() == TypeRawPtr::BOTTOM
6109 || n->is_NarrowMemProj()
6110 || !Compile::current()->do_aliasing(),
6111 "must be a wide memory");
6112 // do_aliasing == false if we are organizing the memory states manually.
6113 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
6114 } else {
6115 // make sure the stored slice is sane
6116 #ifdef ASSERT
6117 if (VMError::is_error_reported() || Node::in_dump()) {
6118 } else if (might_be_same(n, base_memory())) {
6119 // Give it a pass: It is a mostly harmless repetition of the base.
6120 // This can arise normally from node subsumption during optimization.
6121 } else {
6122 verify_memory_slice(this, alias_idx, n);
6123 }
6124 #endif
6125 }
6126 return n;
6127 }
6128
6129 //---------------------------set_memory_at-------------------------------------
6130 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
6131 verify_memory_slice(this, alias_idx, n);
6132 Node* empty_mem = empty_memory();
6133 if (n == base_memory()) n = empty_mem; // collapse default
6134 uint need_req = alias_idx+1;
6135 if (req() < need_req) {
6136 if (n == empty_mem) return; // already the default, so do not grow me
6137 // grow the sparse array
6138 do {
6139 add_req(empty_mem);
6140 } while (req() < need_req);
6141 }
6142 set_req( alias_idx, n );
6143 }
6144
6145
6146
6147 //--------------------------iteration_setup------------------------------------
6148 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
6149 if (other != nullptr) {
6150 grow_to_match(other);
6151 // invariant: the finite support of mm2 is within mm->req()
6152 #ifdef ASSERT
6153 for (uint i = req(); i < other->req(); i++) {
6154 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
6155 }
6156 #endif
6157 }
6158 // Replace spurious copies of base_memory by top.
6159 Node* base_mem = base_memory();
6160 if (base_mem != nullptr && !base_mem->is_top()) {
6161 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
6162 if (in(i) == base_mem)
6163 set_req(i, empty_memory());
6164 }
6165 }
6166 }
6167
6168 //---------------------------grow_to_match-------------------------------------
6169 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
6170 Node* empty_mem = empty_memory();
6171 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
6172 // look for the finite support of the other memory
6173 for (uint i = other->req(); --i >= req(); ) {
6174 if (other->in(i) != empty_mem) {
6175 uint new_len = i+1;
6176 while (req() < new_len) add_req(empty_mem);
6177 break;
6178 }
6179 }
6180 }
6181
6182 //---------------------------verify_sparse-------------------------------------
6183 #ifndef PRODUCT
6184 bool MergeMemNode::verify_sparse() const {
6185 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
6186 Node* base_mem = base_memory();
6187 // The following can happen in degenerate cases, since empty==top.
6188 if (is_empty_memory(base_mem)) return true;
6189 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
6190 assert(in(i) != nullptr, "sane slice");
6191 if (in(i) == base_mem) return false; // should have been the sentinel value!
6192 }
6193 return true;
6194 }
6195
6196 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
6197 Node* n;
6198 n = mm->in(idx);
6199 if (mem == n) return true; // might be empty_memory()
6200 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
6201 if (mem == n) return true;
6202 return false;
6203 }
6204 #endif // !PRODUCT