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 "code/aotCodeCache.hpp"
28 #include "compiler/compileLog.hpp"
29 #include "gc/shared/barrierSet.hpp"
30 #include "gc/shared/c2/barrierSetC2.hpp"
31 #include "gc/shared/tlab_globals.hpp"
32 #include "memory/allocation.inline.hpp"
33 #include "memory/resourceArea.hpp"
34 #include "oops/objArrayKlass.hpp"
35 #include "opto/addnode.hpp"
36 #include "opto/arraycopynode.hpp"
37 #include "opto/cfgnode.hpp"
38 #include "opto/compile.hpp"
39 #include "opto/connode.hpp"
40 #include "opto/convertnode.hpp"
41 #include "opto/loopnode.hpp"
42 #include "opto/machnode.hpp"
43 #include "opto/matcher.hpp"
44 #include "opto/memnode.hpp"
45 #include "opto/mempointer.hpp"
46 #include "opto/mulnode.hpp"
47 #include "opto/narrowptrnode.hpp"
48 #include "opto/opcodes.hpp"
49 #include "opto/phaseX.hpp"
50 #include "opto/regalloc.hpp"
51 #include "opto/regmask.hpp"
52 #include "opto/rootnode.hpp"
53 #include "opto/traceMergeStoresTag.hpp"
54 #include "opto/vectornode.hpp"
55 #include "utilities/align.hpp"
56 #include "utilities/copy.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) return; // node is dead
90 #ifndef ASSERT
91 // fake the missing field
92 const TypePtr* _adr_type = nullptr;
93 if (in(Address) != nullptr)
94 _adr_type = in(Address)->bottom_type()->isa_ptr();
95 #endif
96 dump_adr_type(_adr_type, st);
97
98 Compile* C = Compile::current();
99 if (C->alias_type(_adr_type)->is_volatile()) {
100 st->print(" Volatile!");
101 }
102 if (_unaligned_access) {
103 st->print(" unaligned");
104 }
105 if (_mismatched_access) {
106 st->print(" mismatched");
107 }
108 if (_unsafe_access) {
109 st->print(" unsafe");
110 }
111 }
112
113 void MemNode::dump_adr_type(const TypePtr* adr_type, outputStream* st) {
114 st->print(" @");
115 if (adr_type == nullptr) {
116 st->print("null");
117 } else {
118 adr_type->dump_on(st);
119 Compile* C = Compile::current();
120 Compile::AliasType* atp = nullptr;
121 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type);
122 if (atp == nullptr)
123 st->print(", idx=?\?;");
124 else if (atp->index() == Compile::AliasIdxBot)
125 st->print(", idx=Bot;");
126 else if (atp->index() == Compile::AliasIdxTop)
127 st->print(", idx=Top;");
128 else if (atp->index() == Compile::AliasIdxRaw)
129 st->print(", idx=Raw;");
130 else {
131 ciField* field = atp->field();
132 if (field) {
133 st->print(", name=");
134 field->print_name_on(st);
135 }
136 st->print(", idx=%d;", atp->index());
137 }
138 }
139 }
140
141 extern void print_alias_types();
142
143 #endif
144
145 Node *MemNode::optimize_simple_memory_chain(Node *mchain, const TypeOopPtr *t_oop, Node *load, PhaseGVN *phase) {
146 assert((t_oop != nullptr), "sanity");
147 bool is_instance = t_oop->is_known_instance_field();
148 bool is_boxed_value_load = t_oop->is_ptr_to_boxed_value() &&
149 (load != nullptr) && load->is_Load() &&
150 (phase->is_IterGVN() != nullptr);
151 if (!(is_instance || is_boxed_value_load))
152 return mchain; // don't try to optimize non-instance types
153 uint instance_id = t_oop->instance_id();
154 Node *start_mem = phase->C->start()->proj_out_or_null(TypeFunc::Memory);
155 Node *prev = nullptr;
156 Node *result = mchain;
157 while (prev != result) {
158 prev = result;
159 if (result == start_mem)
160 break; // hit one of our sentinels
161 // skip over a call which does not affect this memory slice
162 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {
163 Node *proj_in = result->in(0);
164 if (proj_in->is_Allocate() && proj_in->_idx == instance_id) {
165 break; // hit one of our sentinels
166 } else if (proj_in->is_Call()) {
167 // ArrayCopyNodes processed here as well
168 CallNode *call = proj_in->as_Call();
169 if (!call->may_modify(t_oop, phase)) { // returns false for instances
170 result = call->in(TypeFunc::Memory);
171 }
172 } else if (proj_in->is_Initialize()) {
173 AllocateNode* alloc = proj_in->as_Initialize()->allocation();
174 // Stop if this is the initialization for the object instance which
175 // contains this memory slice, otherwise skip over it.
176 if ((alloc == nullptr) || (alloc->_idx == instance_id)) {
177 break;
178 }
179 if (is_instance) {
180 result = proj_in->in(TypeFunc::Memory);
181 } else if (is_boxed_value_load) {
182 Node* klass = alloc->in(AllocateNode::KlassNode);
183 const TypeKlassPtr* tklass = phase->type(klass)->is_klassptr();
184 if (tklass->klass_is_exact() && !tklass->exact_klass()->equals(t_oop->is_instptr()->exact_klass())) {
185 result = proj_in->in(TypeFunc::Memory); // not related allocation
186 }
187 }
188 } else if (proj_in->is_MemBar()) {
189 ArrayCopyNode* ac = nullptr;
190 if (ArrayCopyNode::may_modify(t_oop, proj_in->as_MemBar(), phase, ac)) {
191 break;
192 }
193 result = proj_in->in(TypeFunc::Memory);
194 } else if (proj_in->is_top()) {
195 break; // dead code
196 } else {
197 assert(false, "unexpected projection");
198 }
199 } else if (result->is_ClearArray()) {
200 if (!is_instance || !ClearArrayNode::step_through(&result, instance_id, phase)) {
201 // Can not bypass initialization of the instance
202 // we are looking for.
203 break;
204 }
205 // Otherwise skip it (the call updated 'result' value).
206 } else if (result->is_MergeMem()) {
207 result = step_through_mergemem(phase, result->as_MergeMem(), t_oop, nullptr, tty);
208 }
209 }
210 return result;
211 }
212
213 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, Node *load, PhaseGVN *phase) {
214 const TypeOopPtr* t_oop = t_adr->isa_oopptr();
215 if (t_oop == nullptr)
216 return mchain; // don't try to optimize non-oop types
217 Node* result = optimize_simple_memory_chain(mchain, t_oop, load, phase);
218 bool is_instance = t_oop->is_known_instance_field();
219 PhaseIterGVN *igvn = phase->is_IterGVN();
220 if (is_instance && igvn != nullptr && result->is_Phi()) {
221 PhiNode *mphi = result->as_Phi();
222 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
223 const TypePtr *t = mphi->adr_type();
224 bool do_split = false;
225 // In the following cases, Load memory input can be further optimized based on
226 // its precise address type
227 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ) {
228 do_split = true;
229 } else if (t->isa_oopptr() && !t->is_oopptr()->is_known_instance()) {
230 const TypeOopPtr* mem_t =
231 t->is_oopptr()->cast_to_exactness(true)
232 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
233 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id());
234 if (t_oop->isa_aryptr()) {
235 mem_t = mem_t->is_aryptr()
236 ->cast_to_stable(t_oop->is_aryptr()->is_stable())
237 ->cast_to_size(t_oop->is_aryptr()->size())
238 ->with_offset(t_oop->is_aryptr()->offset())
239 ->is_aryptr();
240 }
241 do_split = mem_t == t_oop;
242 }
243 if (do_split) {
244 // clone the Phi with our address type
245 result = mphi->split_out_instance(t_adr, igvn);
246 } else {
247 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain");
248 }
249 }
250 return result;
251 }
252
253 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) {
254 uint alias_idx = phase->C->get_alias_index(tp);
255 Node *mem = mmem;
256 #ifdef ASSERT
257 {
258 // Check that current type is consistent with the alias index used during graph construction
259 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
260 bool consistent = adr_check == nullptr || adr_check->empty() ||
261 phase->C->must_alias(adr_check, alias_idx );
262 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
263 if( !consistent && adr_check != nullptr && !adr_check->empty() &&
264 tp->isa_aryptr() && tp->offset() == Type::OffsetBot &&
265 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot &&
266 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() ||
267 adr_check->offset() == oopDesc::klass_offset_in_bytes() ||
268 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) {
269 // don't assert if it is dead code.
270 consistent = true;
271 }
272 if( !consistent ) {
273 st->print("alias_idx==%d, adr_check==", alias_idx);
274 if( adr_check == nullptr ) {
275 st->print("null");
276 } else {
277 adr_check->dump();
278 }
279 st->cr();
280 print_alias_types();
281 assert(consistent, "adr_check must match alias idx");
282 }
283 }
284 #endif
285 // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally
286 // means an array I have not precisely typed yet. Do not do any
287 // alias stuff with it any time soon.
288 const TypeOopPtr *toop = tp->isa_oopptr();
289 if (tp->base() != Type::AnyPtr &&
290 !(toop &&
291 toop->isa_instptr() &&
292 toop->is_instptr()->instance_klass()->is_java_lang_Object() &&
293 toop->offset() == Type::OffsetBot)) {
294 // IGVN _delay_transform may be set to true and if that is the case and mmem
295 // is already a registered node then the validation inside transform will
296 // complain.
297 Node* m = mmem;
298 PhaseIterGVN* igvn = phase->is_IterGVN();
299 if (igvn == nullptr || !igvn->delay_transform()) {
300 // compress paths and change unreachable cycles to TOP
301 // If not, we can update the input infinitely along a MergeMem cycle
302 // Equivalent code in PhiNode::Ideal
303 m = phase->transform(mmem);
304 }
305 // If transformed to a MergeMem, get the desired slice
306 // Otherwise the returned node represents memory for every slice
307 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
308 // Update input if it is progress over what we have now
309 }
310 return mem;
311 }
312
313 //--------------------------Ideal_common---------------------------------------
314 // Look for degenerate control and memory inputs. Bypass MergeMem inputs.
315 // Unhook non-raw memories from complete (macro-expanded) initializations.
316 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
317 // If our control input is a dead region, kill all below the region
318 Node *ctl = in(MemNode::Control);
319 if (ctl && remove_dead_region(phase, can_reshape))
320 return this;
321 ctl = in(MemNode::Control);
322 // Don't bother trying to transform a dead node
323 if (ctl && ctl->is_top()) return NodeSentinel;
324
325 PhaseIterGVN *igvn = phase->is_IterGVN();
326 // Wait if control on the worklist.
327 if (ctl && can_reshape && igvn != nullptr) {
328 Node* bol = nullptr;
329 Node* cmp = nullptr;
330 if (ctl->in(0)->is_If()) {
331 assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity");
332 bol = ctl->in(0)->in(1);
333 if (bol->is_Bool())
334 cmp = ctl->in(0)->in(1)->in(1);
335 }
336 if (igvn->_worklist.member(ctl) ||
337 (bol != nullptr && igvn->_worklist.member(bol)) ||
338 (cmp != nullptr && igvn->_worklist.member(cmp)) ) {
339 // This control path may be dead.
340 // Delay this memory node transformation until the control is processed.
341 igvn->_worklist.push(this);
342 return NodeSentinel; // caller will return null
343 }
344 }
345 // Ignore if memory is dead, or self-loop
346 Node *mem = in(MemNode::Memory);
347 if (phase->type( mem ) == Type::TOP) return NodeSentinel; // caller will return null
348 assert(mem != this, "dead loop in MemNode::Ideal");
349
350 if (can_reshape && igvn != nullptr && igvn->_worklist.member(mem)) {
351 // This memory slice may be dead.
352 // Delay this mem node transformation until the memory is processed.
353 igvn->_worklist.push(this);
354 return NodeSentinel; // caller will return null
355 }
356
357 Node *address = in(MemNode::Address);
358 const Type *t_adr = phase->type(address);
359 if (t_adr == Type::TOP) return NodeSentinel; // caller will return null
360
361 if (can_reshape && is_unsafe_access() && (t_adr == TypePtr::NULL_PTR)) {
362 // Unsafe off-heap access with zero address. Remove access and other control users
363 // to not confuse optimizations and add a HaltNode to fail if this is ever executed.
364 assert(ctl != nullptr, "unsafe accesses should be control dependent");
365 for (DUIterator_Fast imax, i = ctl->fast_outs(imax); i < imax; i++) {
366 Node* u = ctl->fast_out(i);
367 if (u != ctl) {
368 igvn->rehash_node_delayed(u);
369 int nb = u->replace_edge(ctl, phase->C->top(), igvn);
370 --i, imax -= nb;
371 }
372 }
373 Node* frame = igvn->transform(new ParmNode(phase->C->start(), TypeFunc::FramePtr));
374 Node* halt = igvn->transform(new HaltNode(ctl, frame, "unsafe off-heap access with zero address"));
375 phase->C->root()->add_req(halt);
376 return this;
377 }
378
379 if (can_reshape && igvn != nullptr &&
380 (igvn->_worklist.member(address) ||
381 (igvn->_worklist.size() > 0 && t_adr != adr_type())) ) {
382 // The address's base and type may change when the address is processed.
383 // Delay this mem node transformation until the address is processed.
384 igvn->_worklist.push(this);
385 return NodeSentinel; // caller will return null
386 }
387
388 // Do NOT remove or optimize the next lines: ensure a new alias index
389 // is allocated for an oop pointer type before Escape Analysis.
390 // Note: C++ will not remove it since the call has side effect.
391 if (t_adr->isa_oopptr()) {
392 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr());
393 }
394
395 Node* base = nullptr;
396 if (address->is_AddP()) {
397 base = address->in(AddPNode::Base);
398 }
399 if (base != nullptr && phase->type(base)->higher_equal(TypePtr::NULL_PTR) &&
400 !t_adr->isa_rawptr()) {
401 // Note: raw address has TOP base and top->higher_equal(TypePtr::NULL_PTR) is true.
402 // Skip this node optimization if its address has TOP base.
403 return NodeSentinel; // caller will return null
404 }
405
406 // Avoid independent memory operations
407 Node* old_mem = mem;
408
409 // The code which unhooks non-raw memories from complete (macro-expanded)
410 // initializations was removed. After macro-expansion all stores caught
411 // by Initialize node became raw stores and there is no information
412 // which memory slices they modify. So it is unsafe to move any memory
413 // operation above these stores. Also in most cases hooked non-raw memories
414 // were already unhooked by using information from detect_ptr_independence()
415 // and find_previous_store().
416
417 if (mem->is_MergeMem()) {
418 MergeMemNode* mmem = mem->as_MergeMem();
419 const TypePtr *tp = t_adr->is_ptr();
420
421 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
422 }
423
424 if (mem != old_mem) {
425 set_req_X(MemNode::Memory, mem, phase);
426 if (phase->type(mem) == Type::TOP) return NodeSentinel;
427 return this;
428 }
429
430 // let the subclass continue analyzing...
431 return nullptr;
432 }
433
434 // Helper function for proving some simple control dominations.
435 // Attempt to prove that all control inputs of 'dom' dominate 'sub'.
436 // Already assumes that 'dom' is available at 'sub', and that 'sub'
437 // is not a constant (dominated by the method's StartNode).
438 // Used by MemNode::find_previous_store to prove that the
439 // control input of a memory operation predates (dominates)
440 // an allocation it wants to look past.
441 // Returns 'DomResult::Dominate' if all control inputs of 'dom'
442 // dominate 'sub', 'DomResult::NotDominate' if not,
443 // and 'DomResult::EncounteredDeadCode' if we can't decide due to
444 // dead code, but at the end of IGVN, we know the definite result
445 // once the dead code is cleaned up.
446 Node::DomResult MemNode::maybe_all_controls_dominate(Node* dom, Node* sub) {
447 if (dom == nullptr || dom->is_top() || sub == nullptr || sub->is_top()) {
448 return DomResult::EncounteredDeadCode; // Conservative answer for dead code
449 }
450
451 // Check 'dom'. Skip Proj and CatchProj nodes.
452 dom = dom->find_exact_control(dom);
453 if (dom == nullptr || dom->is_top()) {
454 return DomResult::EncounteredDeadCode; // Conservative answer for dead code
455 }
456
457 if (dom == sub) {
458 // For the case when, for example, 'sub' is Initialize and the original
459 // 'dom' is Proj node of the 'sub'.
460 return DomResult::NotDominate;
461 }
462
463 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub) {
464 return DomResult::Dominate;
465 }
466
467 // 'dom' dominates 'sub' if its control edge and control edges
468 // of all its inputs dominate or equal to sub's control edge.
469
470 // Currently 'sub' is either Allocate, Initialize or Start nodes.
471 // Or Region for the check in LoadNode::Ideal();
472 // 'sub' should have sub->in(0) != nullptr.
473 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() ||
474 sub->is_Region() || sub->is_Call(), "expecting only these nodes");
475
476 // Get control edge of 'sub'.
477 Node* orig_sub = sub;
478 sub = sub->find_exact_control(sub->in(0));
479 if (sub == nullptr || sub->is_top()) {
480 return DomResult::EncounteredDeadCode; // Conservative answer for dead code
481 }
482
483 assert(sub->is_CFG(), "expecting control");
484
485 if (sub == dom) {
486 return DomResult::Dominate;
487 }
488
489 if (sub->is_Start() || sub->is_Root()) {
490 return DomResult::NotDominate;
491 }
492
493 {
494 // Check all control edges of 'dom'.
495
496 ResourceMark rm;
497 Node_List nlist;
498 Unique_Node_List dom_list;
499
500 dom_list.push(dom);
501 bool only_dominating_controls = false;
502
503 for (uint next = 0; next < dom_list.size(); next++) {
504 Node* n = dom_list.at(next);
505 if (n == orig_sub) {
506 return DomResult::NotDominate; // One of dom's inputs dominated by sub.
507 }
508 if (!n->is_CFG() && n->pinned()) {
509 // Check only own control edge for pinned non-control nodes.
510 n = n->find_exact_control(n->in(0));
511 if (n == nullptr || n->is_top()) {
512 return DomResult::EncounteredDeadCode; // Conservative answer for dead code
513 }
514 assert(n->is_CFG(), "expecting control");
515 dom_list.push(n);
516 } else if (n->is_Con() || n->is_Start() || n->is_Root()) {
517 only_dominating_controls = true;
518 } else if (n->is_CFG()) {
519 DomResult dom_result = n->dominates(sub, nlist);
520 if (dom_result == DomResult::Dominate) {
521 only_dominating_controls = true;
522 } else {
523 return dom_result;
524 }
525 } else {
526 // First, own control edge.
527 Node* m = n->find_exact_control(n->in(0));
528 if (m != nullptr) {
529 if (m->is_top()) {
530 return DomResult::EncounteredDeadCode; // Conservative answer for dead code
531 }
532 dom_list.push(m);
533 }
534 // Now, the rest of edges.
535 uint cnt = n->req();
536 for (uint i = 1; i < cnt; i++) {
537 m = n->find_exact_control(n->in(i));
538 if (m == nullptr || m->is_top()) {
539 continue;
540 }
541 dom_list.push(m);
542 }
543 }
544 }
545 return only_dominating_controls ? DomResult::Dominate : DomResult::NotDominate;
546 }
547 }
548
549 //---------------------detect_ptr_independence---------------------------------
550 // Used by MemNode::find_previous_store to prove that two base
551 // pointers are never equal.
552 // The pointers are accompanied by their associated allocations,
553 // if any, which have been previously discovered by the caller.
554 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
555 Node* p2, AllocateNode* a2,
556 PhaseTransform* phase) {
557 // Trivial case: Non-overlapping values. Be careful, we can cast a raw pointer to an oop (e.g. in
558 // the allocation pattern) so joining the types only works if both are oops. join may also give
559 // an incorrect result when both pointers are nullable and the result is supposed to be
560 // TypePtr::NULL_PTR, so we exclude that case.
561 const Type* p1_type = p1->bottom_type();
562 const Type* p2_type = p2->bottom_type();
563 if (p1_type->isa_oopptr() && p2_type->isa_oopptr() &&
564 (!p1_type->maybe_null() || !p2_type->maybe_null()) &&
565 p1_type->join(p2_type)->empty()) {
566 return true;
567 }
568
569 // Attempt to prove that these two pointers cannot be aliased.
570 // They may both manifestly be allocations, and they should differ.
571 // Or, if they are not both allocations, they can be distinct constants.
572 // Otherwise, one is an allocation and the other a pre-existing value.
573 if (a1 == nullptr && a2 == nullptr) { // neither an allocation
574 return (p1 != p2) && p1->is_Con() && p2->is_Con();
575 } else if (a1 != nullptr && a2 != nullptr) { // both allocations
576 return (a1 != a2);
577 } else if (a1 != nullptr) { // one allocation a1
578 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.)
579 return all_controls_dominate(p2, a1);
580 } else { //(a2 != null) // one allocation a2
581 return all_controls_dominate(p1, a2);
582 }
583 return false;
584 }
585
586 // Find an arraycopy ac that produces the memory state represented by parameter mem.
587 // Return ac if
588 // (a) can_see_stored_value=true and ac must have set the value for this load or if
589 // (b) can_see_stored_value=false and ac could have set the value for this load or if
590 // (c) can_see_stored_value=false and ac cannot have set the value for this load.
591 // In case (c) change the parameter mem to the memory input of ac to skip it
592 // when searching stored value.
593 // Otherwise return null.
594 Node* LoadNode::find_previous_arraycopy(PhaseValues* phase, Node* ld_alloc, Node*& mem, bool can_see_stored_value) const {
595 ArrayCopyNode* ac = find_array_copy_clone(ld_alloc, mem);
596 if (ac != nullptr) {
597 Node* ld_addp = in(MemNode::Address);
598 Node* src = ac->in(ArrayCopyNode::Src);
599 const TypeAryPtr* ary_t = phase->type(src)->isa_aryptr();
600
601 // This is a load from a cloned array. The corresponding arraycopy ac must
602 // have set the value for the load and we can return ac but only if the load
603 // is known to be within bounds. This is checked below.
604 if (ary_t != nullptr && ld_addp->is_AddP()) {
605 Node* ld_offs = ld_addp->in(AddPNode::Offset);
606 BasicType ary_elem = ary_t->elem()->array_element_basic_type();
607 jlong header = arrayOopDesc::base_offset_in_bytes(ary_elem);
608 jlong elemsize = type2aelembytes(ary_elem);
609
610 const TypeX* ld_offs_t = phase->type(ld_offs)->isa_intptr_t();
611 const TypeInt* sizetype = ary_t->size();
612
613 if (ld_offs_t->_lo >= header && ld_offs_t->_hi < (sizetype->_lo * elemsize + header)) {
614 // The load is known to be within bounds. It receives its value from ac.
615 return ac;
616 }
617 // The load is known to be out-of-bounds.
618 }
619 // The load could be out-of-bounds. It must not be hoisted but must remain
620 // dependent on the runtime range check. This is achieved by returning null.
621 } else if (mem->is_Proj() && mem->in(0) != nullptr && mem->in(0)->is_ArrayCopy()) {
622 ArrayCopyNode* ac = mem->in(0)->as_ArrayCopy();
623
624 if (ac->is_arraycopy_validated() ||
625 ac->is_copyof_validated() ||
626 ac->is_copyofrange_validated()) {
627 Node* ld_addp = in(MemNode::Address);
628 if (ld_addp->is_AddP()) {
629 Node* ld_base = ld_addp->in(AddPNode::Address);
630 Node* ld_offs = ld_addp->in(AddPNode::Offset);
631
632 Node* dest = ac->in(ArrayCopyNode::Dest);
633
634 if (dest == ld_base) {
635 const TypeX* ld_offs_t = phase->type(ld_offs)->isa_intptr_t();
636 assert(!ld_offs_t->empty(), "dead reference should be checked already");
637 // Take into account vector or unsafe access size
638 jlong ld_size_in_bytes = (jlong)memory_size();
639 jlong offset_hi = ld_offs_t->_hi + ld_size_in_bytes - 1;
640 offset_hi = MIN2(offset_hi, (jlong)(TypeX::MAX->_hi)); // Take care for overflow in 32-bit VM
641 if (ac->modifies(ld_offs_t->_lo, (intptr_t)offset_hi, phase, can_see_stored_value)) {
642 return ac;
643 }
644 if (!can_see_stored_value) {
645 mem = ac->in(TypeFunc::Memory);
646 return ac;
647 }
648 }
649 }
650 }
651 }
652 return nullptr;
653 }
654
655 ArrayCopyNode* MemNode::find_array_copy_clone(Node* ld_alloc, Node* mem) const {
656 if (mem->is_Proj() && mem->in(0) != nullptr && (mem->in(0)->Opcode() == Op_MemBarStoreStore ||
657 mem->in(0)->Opcode() == Op_MemBarCPUOrder)) {
658 if (ld_alloc != nullptr) {
659 // Check if there is an array copy for a clone
660 Node* mb = mem->in(0);
661 ArrayCopyNode* ac = nullptr;
662 if (mb->in(0) != nullptr && mb->in(0)->is_Proj() &&
663 mb->in(0)->in(0) != nullptr && mb->in(0)->in(0)->is_ArrayCopy()) {
664 ac = mb->in(0)->in(0)->as_ArrayCopy();
665 } else {
666 // Step over GC barrier when ReduceInitialCardMarks is disabled
667 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
668 Node* control_proj_ac = bs->step_over_gc_barrier(mb->in(0));
669
670 if (control_proj_ac->is_Proj() && control_proj_ac->in(0)->is_ArrayCopy()) {
671 ac = control_proj_ac->in(0)->as_ArrayCopy();
672 }
673 }
674
675 if (ac != nullptr && ac->is_clonebasic()) {
676 AllocateNode* alloc = AllocateNode::Ideal_allocation(ac->in(ArrayCopyNode::Dest));
677 if (alloc != nullptr && alloc == ld_alloc) {
678 return ac;
679 }
680 }
681 }
682 }
683 return nullptr;
684 }
685
686 // The logic for reordering loads and stores uses four steps:
687 // (a) Walk carefully past stores and initializations which we
688 // can prove are independent of this load.
689 // (b) Observe that the next memory state makes an exact match
690 // with self (load or store), and locate the relevant store.
691 // (c) Ensure that, if we were to wire self directly to the store,
692 // the optimizer would fold it up somehow.
693 // (d) Do the rewiring, and return, depending on some other part of
694 // the optimizer to fold up the load.
695 // This routine handles steps (a) and (b). Steps (c) and (d) are
696 // specific to loads and stores, so they are handled by the callers.
697 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.)
698 //
699 Node* MemNode::find_previous_store(PhaseValues* phase) {
700 AccessAnalyzer analyzer(phase, this);
701
702 Node* mem = in(MemNode::Memory); // start searching here...
703 int cnt = 50; // Cycle limiter
704 for (;; cnt--) {
705 // While we can dance past unrelated stores...
706 if (phase->type(mem) == Type::TOP) {
707 // Encounter a dead node
708 return phase->C->top();
709 } else if (cnt <= 0) {
710 // Caught in cycle or a complicated dance?
711 return nullptr;
712 } else if (mem->is_Phi()) {
713 return nullptr;
714 }
715
716 AccessAnalyzer::AccessIndependence independence = analyzer.detect_access_independence(mem);
717 if (independence.independent) {
718 // (a) advance through the independent store
719 mem = independence.mem;
720 assert(mem != nullptr, "must not be nullptr");
721 } else {
722 // (b) found the store that this access observes if this is not null
723 // Otherwise, give up if it is null
724 return independence.mem;
725 }
726 }
727
728 return nullptr; // bail out
729 }
730
731 //----------------------calculate_adr_type-------------------------------------
732 // Helper function. Notices when the given type of address hits top or bottom.
733 // Also, asserts a cross-check of the type against the expected address type.
734 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
735 if (t == Type::TOP) return nullptr; // does not touch memory any more?
736 #ifdef ASSERT
737 if (!VerifyAliases || VMError::is_error_reported() || Node::in_dump()) cross_check = nullptr;
738 #endif
739 const TypePtr* tp = t->isa_ptr();
740 if (tp == nullptr) {
741 assert(cross_check == nullptr || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
742 return TypePtr::BOTTOM; // touches lots of memory
743 } else {
744 #ifdef ASSERT
745 // %%%% [phh] We don't check the alias index if cross_check is
746 // TypeRawPtr::BOTTOM. Needs to be investigated.
747 if (cross_check != nullptr &&
748 cross_check != TypePtr::BOTTOM &&
749 cross_check != TypeRawPtr::BOTTOM) {
750 // Recheck the alias index, to see if it has changed (due to a bug).
751 Compile* C = Compile::current();
752 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
753 "must stay in the original alias category");
754 // The type of the address must be contained in the adr_type,
755 // disregarding "null"-ness.
756 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
757 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
758 assert(cross_check->meet(tp_notnull) == cross_check->remove_speculative(),
759 "real address must not escape from expected memory type");
760 }
761 #endif
762 return tp;
763 }
764 }
765
766 uint8_t MemNode::barrier_data(const Node* n) {
767 if (n->is_LoadStore()) {
768 return n->as_LoadStore()->barrier_data();
769 } else if (n->is_Mem()) {
770 return n->as_Mem()->barrier_data();
771 }
772 return 0;
773 }
774
775 AccessAnalyzer::AccessAnalyzer(PhaseValues* phase, MemNode* n)
776 : _phase(phase), _n(n), _memory_size(n->memory_size()), _alias_idx(-1) {
777 Node* adr = _n->in(MemNode::Address);
778 _offset = 0;
779 _base = AddPNode::Ideal_base_and_offset(adr, _phase, _offset);
780 _maybe_raw = MemNode::check_if_adr_maybe_raw(adr);
781 _alloc = AllocateNode::Ideal_allocation(_base);
782 _adr_type = _n->adr_type();
783
784 if (_adr_type != nullptr && _adr_type->base() != TypePtr::AnyPtr) {
785 // Avoid the cases that will upset Compile::get_alias_index
786 _alias_idx = _phase->C->get_alias_index(_adr_type);
787 assert(_alias_idx != Compile::AliasIdxTop, "must not be a dead node");
788 assert(_alias_idx != Compile::AliasIdxBot || !phase->C->do_aliasing(), "must not be a very wide access");
789 }
790 }
791
792 // Decide whether the memory accessed by '_n' and 'other' may overlap. This function may be used
793 // when we want to walk the memory graph to fold a load, or when we want to hoist a load above a
794 // loop when there are no stores that may overlap with the load inside the loop.
795 AccessAnalyzer::AccessIndependence AccessAnalyzer::detect_access_independence(Node* other) const {
796 assert(_phase->type(other) == Type::MEMORY, "must be a memory node %s", other->Name());
797 assert(!other->is_Phi(), "caller must handle Phi");
798
799 if (_adr_type == nullptr) {
800 // This means the access is dead
801 return {false, _phase->C->top()};
802 } else if (_adr_type->base() == TypePtr::AnyPtr) {
803 // An example for this case is an access into the memory address 0 performed using Unsafe
804 assert(_adr_type->ptr() == TypePtr::Null, "MemNode should never access a wide memory");
805 return {false, nullptr};
806 }
807
808 if (_offset == Type::OffsetBot) {
809 // cannot unalias unless there are precise offsets
810 return {false, nullptr};
811 }
812
813 const TypeOopPtr* adr_oop_type = _adr_type->isa_oopptr();
814 Node* prev = other;
815 if (other->is_Store()) {
816 Node* st_adr = other->in(MemNode::Address);
817 intptr_t st_offset = 0;
818 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, _phase, st_offset);
819 if (st_base == nullptr) {
820 // inscrutable pointer
821 return {false, nullptr};
822 }
823
824 // If the bases are the same and the offsets are the same, it seems that this is the exact
825 // store we are looking for, the caller will check if the type of the store matches using
826 // MemNode::can_see_stored_value
827 if (st_base == _base && st_offset == _offset) {
828 return {false, other};
829 }
830
831 // If it is provable that the memory accessed by 'other' does not overlap the memory accessed
832 // by '_n', we may walk past 'other'.
833 // For raw accesses, 2 accesses are independent if they have the same base and the offsets
834 // say that they do not overlap.
835 // For heap accesses, 2 accesses are independent if either the bases are provably different
836 // at runtime or the offsets say that the accesses do not overlap.
837 if ((_maybe_raw || MemNode::check_if_adr_maybe_raw(st_adr)) && st_base != _base) {
838 // Raw accesses can only be provably independent if they have the same base
839 return {false, nullptr};
840 }
841
842 // If the offsets say that the accesses do not overlap, then it is provable that 'other' and
843 // '_n' do not overlap. For example, a LoadI from Object+8 is independent from a StoreL into
844 // Object+12, no matter what the bases are.
845 if (st_offset != _offset && st_offset != Type::OffsetBot) {
846 const int MAX_STORE = MAX2(BytesPerLong, (int)MaxVectorSize);
847 assert(other->as_Store()->memory_size() <= MAX_STORE, "");
848 if (st_offset >= _offset + _memory_size ||
849 st_offset <= _offset - MAX_STORE ||
850 st_offset <= _offset - other->as_Store()->memory_size()) {
851 // Success: The offsets are provably independent.
852 // (You may ask, why not just test st_offset != offset and be done?
853 // The answer is that stores of different sizes can co-exist
854 // in the same sequence of RawMem effects. We sometimes initialize
855 // a whole 'tile' of array elements with a single jint or jlong.)
856 return {true, other->in(MemNode::Memory)};
857 }
858 }
859
860 // Same base and overlapping offsets, it seems provable that the accesses overlap, give up
861 if (st_base == _base) {
862 return {false, nullptr};
863 }
864
865 // Try to prove that 2 different base nodes at compile time are different values at runtime
866 bool known_independent = false;
867 if (MemNode::detect_ptr_independence(_base, _alloc, st_base, AllocateNode::Ideal_allocation(st_base), _phase)) {
868 known_independent = true;
869 }
870
871 if (known_independent) {
872 return {true, other->in(MemNode::Memory)};
873 }
874 } else if (other->is_Proj() && other->in(0)->is_Initialize()) {
875 InitializeNode* st_init = other->in(0)->as_Initialize();
876 AllocateNode* st_alloc = st_init->allocation();
877 if (st_alloc == nullptr) {
878 // Something degenerated
879 return {false, nullptr};
880 }
881 bool known_identical = false;
882 bool known_independent = false;
883 if (_alloc == st_alloc) {
884 known_identical = true;
885 } else if (_alloc != nullptr) {
886 known_independent = true;
887 } else if (MemNode::all_controls_dominate(_n, st_alloc)) {
888 known_independent = true;
889 }
890
891 if (known_independent) {
892 // The bases are provably independent: Either they are
893 // manifestly distinct allocations, or else the control
894 // of _n dominates the store's allocation.
895 if (_alias_idx == Compile::AliasIdxRaw) {
896 other = st_alloc->in(TypeFunc::Memory);
897 } else {
898 other = st_init->memory(_alias_idx);
899 }
900 return {true, other};
901 }
902
903 // If we are not looking at a store initializing the same
904 // allocation we are loading from, we lose.
905 if (known_identical) {
906 // From caller, can_see_stored_value will consult find_captured_store.
907 return {false, other};
908 }
909
910 } else if (_n->find_previous_arraycopy(_phase, _alloc, other, false) != nullptr) {
911 // Find an arraycopy that may or may not affect the MemNode
912 return {prev != other, other};
913 } else if (other->is_MergeMem()) {
914 return {true, other->as_MergeMem()->memory_at(_alias_idx)};
915 } else if (adr_oop_type != nullptr && adr_oop_type->is_known_instance_field()) {
916 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
917 if (other->is_Proj() && other->in(0)->is_Call()) {
918 // ArrayCopyNodes processed here as well.
919 CallNode* call = other->in(0)->as_Call();
920 if (!call->may_modify(adr_oop_type, _phase)) {
921 return {true, call->in(TypeFunc::Memory)};
922 }
923 } else if (other->is_Proj() && other->in(0)->is_MemBar()) {
924 ArrayCopyNode* ac = nullptr;
925 if (!ArrayCopyNode::may_modify(adr_oop_type, other->in(0)->as_MemBar(), _phase, ac)) {
926 return {true, other->in(0)->in(TypeFunc::Memory)};
927 }
928 } else if (other->is_ClearArray()) {
929 if (ClearArrayNode::step_through(&other, (uint)adr_oop_type->instance_id(), _phase)) {
930 // (the call updated 'other' value)
931 return {true, other};
932 } else {
933 // Can not bypass initialization of the instance
934 // we are looking for.
935 return {false, other};
936 }
937 }
938 }
939
940 return {false, nullptr};
941 }
942
943 //=============================================================================
944 // Should LoadNode::Ideal() attempt to remove control edges?
945 bool LoadNode::can_remove_control() const {
946 return !has_pinned_control_dependency();
947 }
948 uint LoadNode::size_of() const { return sizeof(*this); }
949 bool LoadNode::cmp(const Node &n) const {
950 LoadNode& load = (LoadNode &)n;
951 return Type::equals(_type, load._type) &&
952 _control_dependency == load._control_dependency &&
953 _mo == load._mo;
954 }
955 const Type *LoadNode::bottom_type() const { return _type; }
956 uint LoadNode::ideal_reg() const {
957 return _type->ideal_reg();
958 }
959
960 #ifndef PRODUCT
961 void LoadNode::dump_spec(outputStream *st) const {
962 MemNode::dump_spec(st);
963 if( !Verbose && !WizardMode ) {
964 // standard dump does this in Verbose and WizardMode
965 st->print(" #"); _type->dump_on(st);
966 }
967 if (in(0) != nullptr && !depends_only_on_test()) {
968 st->print(" (does not depend only on test, ");
969 if (control_dependency() == UnknownControl) {
970 st->print("unknown control");
971 } else if (control_dependency() == Pinned) {
972 st->print("pinned");
973 } else if (adr_type() == TypeRawPtr::BOTTOM) {
974 st->print("raw access");
975 } else {
976 st->print("unknown reason");
977 }
978 st->print(")");
979 }
980 }
981 #endif
982
983 #ifdef ASSERT
984 //----------------------------is_immutable_value-------------------------------
985 // Helper function to allow a raw load without control edge for some cases
986 bool LoadNode::is_immutable_value(Node* adr) {
987 if (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() &&
988 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal) {
989
990 jlong offset = adr->in(AddPNode::Offset)->find_intptr_t_con(-1);
991 int offsets[] = {
992 in_bytes(JavaThread::osthread_offset()),
993 in_bytes(JavaThread::threadObj_offset()),
994 in_bytes(JavaThread::vthread_offset()),
995 in_bytes(JavaThread::scopedValueCache_offset()),
996 };
997
998 for (size_t i = 0; i < sizeof offsets / sizeof offsets[0]; i++) {
999 if (offset == offsets[i]) {
1000 return true;
1001 }
1002 }
1003 }
1004
1005 return false;
1006 }
1007 #endif
1008
1009 //----------------------------LoadNode::make-----------------------------------
1010 // Polymorphic factory method:
1011 Node* LoadNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, BasicType bt, MemOrd mo,
1012 ControlDependency control_dependency, bool require_atomic_access, bool unaligned, bool mismatched, bool unsafe, uint8_t barrier_data) {
1013 Compile* C = gvn.C;
1014 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");
1015
1016 // sanity check the alias category against the created node type
1017 assert(!(adr_type->isa_oopptr() &&
1018 adr_type->offset() == oopDesc::klass_offset_in_bytes()),
1019 "use LoadKlassNode instead");
1020 assert(!(adr_type->isa_aryptr() &&
1021 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
1022 "use LoadRangeNode instead");
1023 // Check control edge of raw loads
1024 assert( ctl != nullptr || C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
1025 // oop will be recorded in oop map if load crosses safepoint
1026 rt->isa_oopptr() || is_immutable_value(adr),
1027 "raw memory operations should have control edge");
1028 LoadNode* load = nullptr;
1029 switch (bt) {
1030 case T_BOOLEAN: load = new LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
1031 case T_BYTE: load = new LoadBNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
1032 case T_INT: load = new LoadINode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
1033 case T_CHAR: load = new LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
1034 case T_SHORT: load = new LoadSNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
1035 case T_LONG: load = new LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency, require_atomic_access); break;
1036 case T_FLOAT: load = new LoadFNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); break;
1037 case T_DOUBLE: load = new LoadDNode (ctl, mem, adr, adr_type, rt, mo, control_dependency, require_atomic_access); break;
1038 case T_ADDRESS: load = new LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency); break;
1039 case T_OBJECT:
1040 case T_NARROWOOP:
1041 #ifdef _LP64
1042 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
1043 load = new LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo, control_dependency);
1044 } else
1045 #endif
1046 {
1047 assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop");
1048 load = new LoadPNode(ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency);
1049 }
1050 break;
1051 default:
1052 ShouldNotReachHere();
1053 break;
1054 }
1055 assert(load != nullptr, "LoadNode should have been created");
1056 if (unaligned) {
1057 load->set_unaligned_access();
1058 }
1059 if (mismatched) {
1060 load->set_mismatched_access();
1061 }
1062 if (unsafe) {
1063 load->set_unsafe_access();
1064 }
1065 load->set_barrier_data(barrier_data);
1066 if (load->Opcode() == Op_LoadN) {
1067 Node* ld = gvn.transform(load);
1068 return new DecodeNNode(ld, ld->bottom_type()->make_ptr());
1069 }
1070
1071 return load;
1072 }
1073
1074 //------------------------------hash-------------------------------------------
1075 uint LoadNode::hash() const {
1076 // unroll addition of interesting fields
1077 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
1078 }
1079
1080 static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) {
1081 if ((atp != nullptr) && (atp->index() >= Compile::AliasIdxRaw)) {
1082 bool non_volatile = (atp->field() != nullptr) && !atp->field()->is_volatile();
1083 bool is_stable_ary = FoldStableValues &&
1084 (tp != nullptr) && (tp->isa_aryptr() != nullptr) &&
1085 tp->isa_aryptr()->is_stable();
1086
1087 return (eliminate_boxing && non_volatile) || is_stable_ary;
1088 }
1089
1090 return false;
1091 }
1092
1093 // Is the value loaded previously stored by an arraycopy? If so return
1094 // a load node that reads from the source array so we may be able to
1095 // optimize out the ArrayCopy node later.
1096 Node* LoadNode::can_see_arraycopy_value(Node* st, PhaseGVN* phase) const {
1097 Node* ld_adr = in(MemNode::Address);
1098 intptr_t ld_off = 0;
1099 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
1100 Node* ac = find_previous_arraycopy(phase, ld_alloc, st, true);
1101 if (ac != nullptr) {
1102 assert(ac->is_ArrayCopy(), "what kind of node can this be?");
1103
1104 Node* mem = ac->in(TypeFunc::Memory);
1105 Node* ctl = ac->in(0);
1106 Node* src = ac->in(ArrayCopyNode::Src);
1107
1108 if (!ac->as_ArrayCopy()->is_clonebasic() && !phase->type(src)->isa_aryptr()) {
1109 return nullptr;
1110 }
1111
1112 // load depends on the tests that validate the arraycopy
1113 LoadNode* ld = clone_pinned();
1114 Node* addp = in(MemNode::Address)->clone();
1115 if (ac->as_ArrayCopy()->is_clonebasic()) {
1116 assert(ld_alloc != nullptr, "need an alloc");
1117 assert(addp->is_AddP(), "address must be addp");
1118 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1119 assert(bs->step_over_gc_barrier(addp->in(AddPNode::Base)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)), "strange pattern");
1120 assert(bs->step_over_gc_barrier(addp->in(AddPNode::Address)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)), "strange pattern");
1121 addp->set_req(AddPNode::Base, src);
1122 addp->set_req(AddPNode::Address, src);
1123 } else {
1124 assert(ac->as_ArrayCopy()->is_arraycopy_validated() ||
1125 ac->as_ArrayCopy()->is_copyof_validated() ||
1126 ac->as_ArrayCopy()->is_copyofrange_validated(), "only supported cases");
1127 assert(addp->in(AddPNode::Base) == addp->in(AddPNode::Address), "should be");
1128 addp->set_req(AddPNode::Base, src);
1129 addp->set_req(AddPNode::Address, src);
1130
1131 const TypeAryPtr* ary_t = phase->type(in(MemNode::Address))->isa_aryptr();
1132 BasicType ary_elem = ary_t->isa_aryptr()->elem()->array_element_basic_type();
1133 if (is_reference_type(ary_elem, true)) ary_elem = T_OBJECT;
1134
1135 uint header = arrayOopDesc::base_offset_in_bytes(ary_elem);
1136 uint shift = exact_log2(type2aelembytes(ary_elem));
1137
1138 Node* diff = phase->transform(new SubINode(ac->in(ArrayCopyNode::SrcPos), ac->in(ArrayCopyNode::DestPos)));
1139 #ifdef _LP64
1140 diff = phase->transform(new ConvI2LNode(diff));
1141 #endif
1142 diff = phase->transform(new LShiftXNode(diff, phase->intcon(shift)));
1143
1144 Node* offset = phase->transform(new AddXNode(addp->in(AddPNode::Offset), diff));
1145 addp->set_req(AddPNode::Offset, offset);
1146 }
1147 addp = phase->transform(addp);
1148 #ifdef ASSERT
1149 const TypePtr* adr_type = phase->type(addp)->is_ptr();
1150 ld->_adr_type = adr_type;
1151 #endif
1152 ld->set_req(MemNode::Address, addp);
1153 ld->set_req(0, ctl);
1154 ld->set_req(MemNode::Memory, mem);
1155 return ld;
1156 }
1157 return nullptr;
1158 }
1159
1160
1161 //---------------------------can_see_stored_value------------------------------
1162 // This routine exists to make sure this set of tests is done the same
1163 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
1164 // will change the graph shape in a way which makes memory alive twice at the
1165 // same time (uses the Oracle model of aliasing), then some
1166 // LoadXNode::Identity will fold things back to the equivalence-class model
1167 // of aliasing.
1168 Node* MemNode::can_see_stored_value(Node* st, PhaseValues* phase) const {
1169 Node* ld_adr = in(MemNode::Address);
1170 intptr_t ld_off = 0;
1171 Node* ld_base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ld_off);
1172 Node* ld_alloc = AllocateNode::Ideal_allocation(ld_base);
1173 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
1174 Compile::AliasType* atp = (tp != nullptr) ? phase->C->alias_type(tp) : nullptr;
1175 // This is more general than load from boxing objects.
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
1181 // new states for the slice of this load. Stop once any other
1182 // kind of node is encountered. Loads from final memory can skip
1183 // through any kind of MemBar but normal loads shouldn't skip
1184 // through MemBarAcquire since the could allow them to move out of
1185 // a synchronized region. It is not safe to step over MemBarCPUOrder,
1186 // because alias info above them may be inaccurate (e.g., due to
1187 // mixed/mismatched unsafe accesses).
1188 bool is_final_mem = !atp->is_rewritable();
1189 while (current->is_Proj()) {
1190 int opc = current->in(0)->Opcode();
1191 if ((is_final_mem && (opc == Op_MemBarAcquire ||
1192 opc == Op_MemBarAcquireLock ||
1193 opc == Op_LoadFence)) ||
1194 opc == Op_MemBarRelease ||
1195 opc == Op_StoreFence ||
1196 opc == Op_MemBarReleaseLock ||
1197 opc == Op_MemBarStoreStore ||
1198 opc == Op_StoreStoreFence) {
1199 Node* mem = current->in(0)->in(TypeFunc::Memory);
1200 if (mem->is_MergeMem()) {
1201 MergeMemNode* merge = mem->as_MergeMem();
1202 Node* new_st = merge->memory_at(alias_idx);
1203 if (new_st == merge->base_memory()) {
1204 // Keep searching
1205 current = new_st;
1206 continue;
1207 }
1208 // Save the new memory state for the slice and fall through
1209 // to exit.
1210 result = new_st;
1211 }
1212 }
1213 break;
1214 }
1215 if (result != nullptr) {
1216 st = result;
1217 }
1218 }
1219
1220 // Loop around twice in the case Load -> Initialize -> Store.
1221 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
1222 for (int trip = 0; trip <= 1; trip++) {
1223
1224 if (st->is_Store()) {
1225 Node* st_adr = st->in(MemNode::Address);
1226 if (st_adr != ld_adr) {
1227 // Try harder before giving up. Unify base pointers with casts (e.g., raw/non-raw pointers).
1228 intptr_t st_off = 0;
1229 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_off);
1230 if (ld_base == nullptr) return nullptr;
1231 if (st_base == nullptr) return nullptr;
1232 if (!ld_base->eqv_uncast(st_base, /*keep_deps=*/true)) return nullptr;
1233 if (ld_off != st_off) return nullptr;
1234 if (ld_off == Type::OffsetBot) return nullptr;
1235 // Same base, same offset.
1236 // Possible improvement for arrays: check index value instead of absolute offset.
1237
1238 // At this point we have proven something like this setup:
1239 // B = << base >>
1240 // L = LoadQ(AddP(Check/CastPP(B), #Off))
1241 // S = StoreQ(AddP( B , #Off), V)
1242 // (Actually, we haven't yet proven the Q's are the same.)
1243 // In other words, we are loading from a casted version of
1244 // the same pointer-and-offset that we stored to.
1245 // Casted version may carry a dependency and it is respected.
1246 // Thus, we are able to replace L by V.
1247 }
1248 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
1249 if (store_Opcode() != st->Opcode()) {
1250 return nullptr;
1251 }
1252 // LoadVector/StoreVector needs additional check to ensure the types match.
1253 if (st->is_StoreVector()) {
1254 if ((Opcode() != Op_LoadVector && Opcode() != Op_StoreVector) || st->Opcode() != Op_StoreVector) {
1255 // Some kind of masked access or gather/scatter
1256 return nullptr;
1257 }
1258
1259 const TypeVect* in_vt = st->as_StoreVector()->vect_type();
1260 const TypeVect* out_vt = is_Load() ? as_LoadVector()->vect_type() : as_StoreVector()->vect_type();
1261 if (in_vt != out_vt) {
1262 return nullptr;
1263 }
1264 }
1265 return st->in(MemNode::ValueIn);
1266 }
1267
1268 // A load from a freshly-created object always returns zero.
1269 // (This can happen after LoadNode::Ideal resets the load's memory input
1270 // to find_captured_store, which returned InitializeNode::zero_memory.)
1271 if (st->is_Proj() && st->in(0)->is_Allocate() &&
1272 (st->in(0) == ld_alloc) &&
1273 (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) {
1274 // return a zero value for the load's basic type
1275 // (This is one of the few places where a generic PhaseTransform
1276 // can create new nodes. Think of it as lazily manifesting
1277 // virtually pre-existing constants.)
1278 if (value_basic_type() != T_VOID) {
1279 if (ReduceBulkZeroing || find_array_copy_clone(ld_alloc, in(MemNode::Memory)) == nullptr) {
1280 // If ReduceBulkZeroing is disabled, we need to check if the allocation does not belong to an
1281 // ArrayCopyNode clone. If it does, then we cannot assume zero since the initialization is done
1282 // by the ArrayCopyNode.
1283 return phase->zerocon(value_basic_type());
1284 }
1285 } else {
1286 // TODO: materialize all-zero vector constant
1287 assert(!isa_Load() || as_Load()->type()->isa_vect(), "");
1288 }
1289 }
1290
1291 // A load from an initialization barrier can match a captured store.
1292 if (st->is_Proj() && st->in(0)->is_Initialize()) {
1293 InitializeNode* init = st->in(0)->as_Initialize();
1294 AllocateNode* alloc = init->allocation();
1295 if ((alloc != nullptr) && (alloc == ld_alloc)) {
1296 // examine a captured store value
1297 st = init->find_captured_store(ld_off, memory_size(), phase);
1298 if (st != nullptr) {
1299 continue; // take one more trip around
1300 }
1301 }
1302 }
1303
1304 // Load boxed value from result of valueOf() call is input parameter.
1305 if (this->is_Load() && ld_adr->is_AddP() &&
1306 (tp != nullptr) && tp->is_ptr_to_boxed_value()) {
1307 intptr_t ignore = 0;
1308 Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore);
1309 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1310 base = bs->step_over_gc_barrier(base);
1311 if (base != nullptr && base->is_Proj() &&
1312 base->as_Proj()->_con == TypeFunc::Parms &&
1313 base->in(0)->is_CallStaticJava() &&
1314 base->in(0)->as_CallStaticJava()->is_boxing_method()) {
1315 return base->in(0)->in(TypeFunc::Parms);
1316 }
1317 }
1318
1319 break;
1320 }
1321
1322 return nullptr;
1323 }
1324
1325 //----------------------is_instance_field_load_with_local_phi------------------
1326 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
1327 if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl &&
1328 in(Address)->is_AddP() ) {
1329 const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr();
1330 // Only instances and boxed values.
1331 if( t_oop != nullptr &&
1332 (t_oop->is_ptr_to_boxed_value() ||
1333 t_oop->is_known_instance_field()) &&
1334 t_oop->offset() != Type::OffsetBot &&
1335 t_oop->offset() != Type::OffsetTop) {
1336 return true;
1337 }
1338 }
1339 return false;
1340 }
1341
1342 //------------------------------Identity---------------------------------------
1343 // Loads are identity if previous store is to same address
1344 Node* LoadNode::Identity(PhaseGVN* phase) {
1345 // If the previous store-maker is the right kind of Store, and the store is
1346 // to the same address, then we are equal to the value stored.
1347 Node* mem = in(Memory);
1348 Node* value = can_see_stored_value(mem, phase);
1349 if( value ) {
1350 // byte, short & char stores truncate naturally.
1351 // A load has to load the truncated value which requires
1352 // some sort of masking operation and that requires an
1353 // Ideal call instead of an Identity call.
1354 if (memory_size() < BytesPerInt) {
1355 // If the input to the store does not fit with the load's result type,
1356 // it must be truncated via an Ideal call.
1357 if (!phase->type(value)->higher_equal(phase->type(this)))
1358 return this;
1359 }
1360 // (This works even when value is a Con, but LoadNode::Value
1361 // usually runs first, producing the singleton type of the Con.)
1362 if (!has_pinned_control_dependency() || value->is_Con()) {
1363 return value;
1364 } else {
1365 return this;
1366 }
1367 }
1368
1369 if (has_pinned_control_dependency()) {
1370 return this;
1371 }
1372 // Search for an existing data phi which was generated before for the same
1373 // instance's field to avoid infinite generation of phis in a loop.
1374 Node *region = mem->in(0);
1375 if (is_instance_field_load_with_local_phi(region)) {
1376 const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr();
1377 int this_index = phase->C->get_alias_index(addr_t);
1378 int this_offset = addr_t->offset();
1379 int this_iid = addr_t->instance_id();
1380 if (!addr_t->is_known_instance() &&
1381 addr_t->is_ptr_to_boxed_value()) {
1382 // Use _idx of address base (could be Phi node) for boxed values.
1383 intptr_t ignore = 0;
1384 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1385 if (base == nullptr) {
1386 return this;
1387 }
1388 this_iid = base->_idx;
1389 }
1390 const Type* this_type = bottom_type();
1391 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1392 Node* phi = region->fast_out(i);
1393 if (phi->is_Phi() && phi != mem &&
1394 phi->as_Phi()->is_same_inst_field(this_type, (int)mem->_idx, this_iid, this_index, this_offset)) {
1395 return phi;
1396 }
1397 }
1398 }
1399
1400 return this;
1401 }
1402
1403 // Construct an equivalent unsigned load.
1404 Node* LoadNode::convert_to_unsigned_load(PhaseGVN& gvn) {
1405 BasicType bt = T_ILLEGAL;
1406 const Type* rt = nullptr;
1407 switch (Opcode()) {
1408 case Op_LoadUB: return this;
1409 case Op_LoadUS: return this;
1410 case Op_LoadB: bt = T_BOOLEAN; rt = TypeInt::UBYTE; break;
1411 case Op_LoadS: bt = T_CHAR; rt = TypeInt::CHAR; break;
1412 default:
1413 assert(false, "no unsigned variant: %s", Name());
1414 return nullptr;
1415 }
1416 const Type* mem_t = gvn.type(in(MemNode::Address));
1417 if (mem_t == Type::TOP) {
1418 return gvn.C->top();
1419 }
1420 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1421 mem_t->is_ptr(), rt, bt, _mo, _control_dependency,
1422 false /*require_atomic_access*/, is_unaligned_access(), is_mismatched_access());
1423 }
1424
1425 // Construct an equivalent signed load.
1426 Node* LoadNode::convert_to_signed_load(PhaseGVN& gvn) {
1427 BasicType bt = T_ILLEGAL;
1428 const Type* rt = nullptr;
1429 switch (Opcode()) {
1430 case Op_LoadUB: bt = T_BYTE; rt = TypeInt::BYTE; break;
1431 case Op_LoadUS: bt = T_SHORT; rt = TypeInt::SHORT; break;
1432 case Op_LoadB: // fall through
1433 case Op_LoadS: // fall through
1434 case Op_LoadI: // fall through
1435 case Op_LoadL: return this;
1436 default:
1437 assert(false, "no signed variant: %s", Name());
1438 return nullptr;
1439 }
1440 const Type* mem_t = gvn.type(in(MemNode::Address));
1441 if (mem_t == Type::TOP) {
1442 return gvn.C->top();
1443 }
1444 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1445 mem_t->is_ptr(), rt, bt, _mo, _control_dependency,
1446 false /*require_atomic_access*/, is_unaligned_access(), is_mismatched_access());
1447 }
1448
1449 bool LoadNode::has_reinterpret_variant(const Type* rt) {
1450 BasicType bt = rt->basic_type();
1451 switch (Opcode()) {
1452 case Op_LoadI: return (bt == T_FLOAT);
1453 case Op_LoadL: return (bt == T_DOUBLE);
1454 case Op_LoadF: return (bt == T_INT);
1455 case Op_LoadD: return (bt == T_LONG);
1456
1457 default: return false;
1458 }
1459 }
1460
1461 Node* LoadNode::convert_to_reinterpret_load(PhaseGVN& gvn, const Type* rt) {
1462 BasicType bt = rt->basic_type();
1463 assert(has_reinterpret_variant(rt), "no reinterpret variant: %s %s", Name(), type2name(bt));
1464 bool is_mismatched = is_mismatched_access();
1465 const TypeRawPtr* raw_type = gvn.type(in(MemNode::Memory))->isa_rawptr();
1466 if (raw_type == nullptr) {
1467 is_mismatched = true; // conservatively match all non-raw accesses as mismatched
1468 }
1469 const int op = Opcode();
1470 bool require_atomic_access = (op == Op_LoadL && ((LoadLNode*)this)->require_atomic_access()) ||
1471 (op == Op_LoadD && ((LoadDNode*)this)->require_atomic_access());
1472 const Type* mem_t = gvn.type(in(MemNode::Address));
1473 if (mem_t == Type::TOP) {
1474 return gvn.C->top();
1475 }
1476 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1477 mem_t->is_ptr(), rt, bt, _mo, _control_dependency,
1478 require_atomic_access, is_unaligned_access(), is_mismatched);
1479 }
1480
1481 bool StoreNode::has_reinterpret_variant(const Type* vt) {
1482 BasicType bt = vt->basic_type();
1483 switch (Opcode()) {
1484 case Op_StoreI: return (bt == T_FLOAT);
1485 case Op_StoreL: return (bt == T_DOUBLE);
1486 case Op_StoreF: return (bt == T_INT);
1487 case Op_StoreD: return (bt == T_LONG);
1488
1489 default: return false;
1490 }
1491 }
1492
1493 Node* StoreNode::convert_to_reinterpret_store(PhaseGVN& gvn, Node* val, const Type* vt) {
1494 BasicType bt = vt->basic_type();
1495 assert(has_reinterpret_variant(vt), "no reinterpret variant: %s %s", Name(), type2name(bt));
1496 const int op = Opcode();
1497 bool require_atomic_access = (op == Op_StoreL && ((StoreLNode*)this)->require_atomic_access()) ||
1498 (op == Op_StoreD && ((StoreDNode*)this)->require_atomic_access());
1499 const Type* mem_t = gvn.type(in(MemNode::Address));
1500 if (mem_t == Type::TOP) {
1501 return gvn.C->top();
1502 }
1503 StoreNode* st = StoreNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1504 mem_t->is_ptr(), val, bt, _mo, require_atomic_access);
1505
1506 bool is_mismatched = is_mismatched_access();
1507 const TypeRawPtr* raw_type = gvn.type(in(MemNode::Memory))->isa_rawptr();
1508 if (raw_type == nullptr) {
1509 is_mismatched = true; // conservatively match all non-raw accesses as mismatched
1510 }
1511 if (is_mismatched) {
1512 st->set_mismatched_access();
1513 }
1514 return st;
1515 }
1516
1517 // We're loading from an object which has autobox behaviour.
1518 // If this object is result of a valueOf call we'll have a phi
1519 // merging a newly allocated object and a load from the cache.
1520 // We want to replace this load with the original incoming
1521 // argument to the valueOf call.
1522 Node* LoadNode::eliminate_autobox(PhaseIterGVN* igvn) {
1523 assert(igvn->C->eliminate_boxing(), "sanity");
1524 intptr_t ignore = 0;
1525 Node* base = AddPNode::Ideal_base_and_offset(in(Address), igvn, ignore);
1526 if ((base == nullptr) || base->is_Phi()) {
1527 // Push the loads from the phi that comes from valueOf up
1528 // through it to allow elimination of the loads and the recovery
1529 // of the original value. It is done in split_through_phi().
1530 return nullptr;
1531 } else if (base->is_Load() ||
1532 (base->is_DecodeN() && base->in(1)->is_Load())) {
1533 // Eliminate the load of boxed value for integer types from the cache
1534 // array by deriving the value from the index into the array.
1535 // Capture the offset of the load and then reverse the computation.
1536
1537 // Get LoadN node which loads a boxing object from 'cache' array.
1538 if (base->is_DecodeN()) {
1539 base = base->in(1);
1540 }
1541 if (!base->in(Address)->is_AddP()) {
1542 return nullptr; // Complex address
1543 }
1544 AddPNode* address = base->in(Address)->as_AddP();
1545 Node* cache_base = address->in(AddPNode::Base);
1546 if ((cache_base != nullptr) && cache_base->is_DecodeN()) {
1547 // Get ConP node which is static 'cache' field.
1548 cache_base = cache_base->in(1);
1549 }
1550 if ((cache_base != nullptr) && cache_base->is_Con()) {
1551 const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr();
1552 if ((base_type != nullptr) && base_type->is_autobox_cache()) {
1553 Node* elements[4];
1554 int shift = exact_log2(type2aelembytes(T_OBJECT));
1555 int count = address->unpack_offsets(elements, ARRAY_SIZE(elements));
1556 if (count > 0 && elements[0]->is_Con() &&
1557 (count == 1 ||
1558 (count == 2 && elements[1]->Opcode() == Op_LShiftX &&
1559 elements[1]->in(2) == igvn->intcon(shift)))) {
1560 ciObjArray* array = base_type->const_oop()->as_obj_array();
1561 // Fetch the box object cache[0] at the base of the array and get its value
1562 ciInstance* box = array->obj_at(0)->as_instance();
1563 ciInstanceKlass* ik = box->klass()->as_instance_klass();
1564 assert(ik->is_box_klass(), "sanity");
1565 assert(ik->nof_nonstatic_fields() == 1, "change following code");
1566 if (ik->nof_nonstatic_fields() == 1) {
1567 // This should be true nonstatic_field_at requires calling
1568 // nof_nonstatic_fields so check it anyway
1569 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1570 BasicType bt = c.basic_type();
1571 // Only integer types have boxing cache.
1572 assert(bt == T_BOOLEAN || bt == T_CHAR ||
1573 bt == T_BYTE || bt == T_SHORT ||
1574 bt == T_INT || bt == T_LONG, "wrong type = %s", type2name(bt));
1575 jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int();
1576 if (cache_low != (int)cache_low) {
1577 return nullptr; // should not happen since cache is array indexed by value
1578 }
1579 jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift);
1580 if (offset != (int)offset) {
1581 return nullptr; // should not happen since cache is array indexed by value
1582 }
1583 // Add up all the offsets making of the address of the load
1584 Node* result = elements[0];
1585 for (int i = 1; i < count; i++) {
1586 result = igvn->transform(new AddXNode(result, elements[i]));
1587 }
1588 // Remove the constant offset from the address and then
1589 result = igvn->transform(new AddXNode(result, igvn->MakeConX(-(int)offset)));
1590 // remove the scaling of the offset to recover the original index.
1591 if (result->Opcode() == Op_LShiftX && result->in(2) == igvn->intcon(shift)) {
1592 // Peel the shift off directly but wrap it in a dummy node
1593 // since Ideal can't return existing nodes
1594 igvn->_worklist.push(result); // remove dead node later
1595 result = new RShiftXNode(result->in(1), igvn->intcon(0));
1596 } else if (result->is_Add() && result->in(2)->is_Con() &&
1597 result->in(1)->Opcode() == Op_LShiftX &&
1598 result->in(1)->in(2) == igvn->intcon(shift)) {
1599 // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z)
1600 // but for boxing cache access we know that X<<Z will not overflow
1601 // (there is range check) so we do this optimizatrion by hand here.
1602 igvn->_worklist.push(result); // remove dead node later
1603 Node* add_con = new RShiftXNode(result->in(2), igvn->intcon(shift));
1604 result = new AddXNode(result->in(1)->in(1), igvn->transform(add_con));
1605 } else {
1606 result = new RShiftXNode(result, igvn->intcon(shift));
1607 }
1608 #ifdef _LP64
1609 if (bt != T_LONG) {
1610 result = new ConvL2INode(igvn->transform(result));
1611 }
1612 #else
1613 if (bt == T_LONG) {
1614 result = new ConvI2LNode(igvn->transform(result));
1615 }
1616 #endif
1617 // Boxing/unboxing can be done from signed & unsigned loads (e.g. LoadUB -> ... -> LoadB pair).
1618 // Need to preserve unboxing load type if it is unsigned.
1619 switch(this->Opcode()) {
1620 case Op_LoadUB:
1621 result = new AndINode(igvn->transform(result), igvn->intcon(0xFF));
1622 break;
1623 case Op_LoadUS:
1624 result = new AndINode(igvn->transform(result), igvn->intcon(0xFFFF));
1625 break;
1626 }
1627 return result;
1628 }
1629 }
1630 }
1631 }
1632 }
1633 return nullptr;
1634 }
1635
1636 static bool stable_phi(PhiNode* phi, PhaseGVN *phase) {
1637 Node* region = phi->in(0);
1638 if (region == nullptr) {
1639 return false; // Wait stable graph
1640 }
1641 uint cnt = phi->req();
1642 for (uint i = 1; i < cnt; i++) {
1643 Node* rc = region->in(i);
1644 if (rc == nullptr || phase->type(rc) == Type::TOP)
1645 return false; // Wait stable graph
1646 Node* in = phi->in(i);
1647 if (in == nullptr || phase->type(in) == Type::TOP)
1648 return false; // Wait stable graph
1649 }
1650 return true;
1651 }
1652
1653 //------------------------------split_through_phi------------------------------
1654 // Check whether a call to 'split_through_phi' would split this load through the
1655 // Phi *base*. This method is essentially a copy of the validations performed
1656 // by 'split_through_phi'. The first use of this method was in EA code as part
1657 // of simplification of allocation merges.
1658 // Some differences from original method (split_through_phi):
1659 // - If base->is_CastPP(): base = base->in(1)
1660 bool LoadNode::can_split_through_phi_base(PhaseGVN* phase) {
1661 Node* mem = in(Memory);
1662 Node* address = in(Address);
1663 intptr_t ignore = 0;
1664 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1665
1666 if (base->is_CastPP()) {
1667 base = base->in(1);
1668 }
1669
1670 if (req() > 3 || base == nullptr || !base->is_Phi()) {
1671 return false;
1672 }
1673
1674 if (!mem->is_Phi()) {
1675 if (!MemNode::all_controls_dominate(mem, base->in(0))) {
1676 return false;
1677 }
1678 } else if (base->in(0) != mem->in(0)) {
1679 if (!MemNode::all_controls_dominate(mem, base->in(0))) {
1680 return false;
1681 }
1682 }
1683
1684 return true;
1685 }
1686
1687 //------------------------------split_through_phi------------------------------
1688 // Split instance or boxed field load through Phi.
1689 Node* LoadNode::split_through_phi(PhaseGVN* phase, bool ignore_missing_instance_id) {
1690 if (req() > 3) {
1691 assert(is_LoadVector() && Opcode() != Op_LoadVector, "load has too many inputs");
1692 // LoadVector subclasses such as LoadVectorMasked have extra inputs that the logic below doesn't take into account
1693 return nullptr;
1694 }
1695 Node* mem = in(Memory);
1696 Node* address = in(Address);
1697 const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr();
1698
1699 assert((t_oop != nullptr) &&
1700 (ignore_missing_instance_id ||
1701 t_oop->is_known_instance_field() ||
1702 t_oop->is_ptr_to_boxed_value()), "invalid conditions");
1703
1704 Compile* C = phase->C;
1705 intptr_t ignore = 0;
1706 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1707 bool base_is_phi = (base != nullptr) && base->is_Phi();
1708 bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() &&
1709 (base != nullptr) && (base == address->in(AddPNode::Base)) &&
1710 phase->type(base)->higher_equal(TypePtr::NOTNULL);
1711
1712 if (!((mem->is_Phi() || base_is_phi) &&
1713 (ignore_missing_instance_id || load_boxed_values || t_oop->is_known_instance_field()))) {
1714 return nullptr; // Neither memory or base are Phi
1715 }
1716
1717 if (mem->is_Phi()) {
1718 if (!stable_phi(mem->as_Phi(), phase)) {
1719 return nullptr; // Wait stable graph
1720 }
1721 uint cnt = mem->req();
1722 // Check for loop invariant memory.
1723 if (cnt == 3) {
1724 for (uint i = 1; i < cnt; i++) {
1725 Node* in = mem->in(i);
1726 Node* m = optimize_memory_chain(in, t_oop, this, phase);
1727 if (m == mem) {
1728 if (i == 1) {
1729 // if the first edge was a loop, check second edge too.
1730 // If both are replaceable - we are in an infinite loop
1731 Node *n = optimize_memory_chain(mem->in(2), t_oop, this, phase);
1732 if (n == mem) {
1733 break;
1734 }
1735 }
1736 set_req(Memory, mem->in(cnt - i));
1737 return this; // made change
1738 }
1739 }
1740 }
1741 }
1742 if (base_is_phi) {
1743 if (!stable_phi(base->as_Phi(), phase)) {
1744 return nullptr; // Wait stable graph
1745 }
1746 uint cnt = base->req();
1747 // Check for loop invariant memory.
1748 if (cnt == 3) {
1749 for (uint i = 1; i < cnt; i++) {
1750 if (base->in(i) == base) {
1751 return nullptr; // Wait stable graph
1752 }
1753 }
1754 }
1755 }
1756
1757 // Split through Phi (see original code in loopopts.cpp).
1758 assert(ignore_missing_instance_id || C->have_alias_type(t_oop), "instance should have alias type");
1759
1760 // Do nothing here if Identity will find a value
1761 // (to avoid infinite chain of value phis generation).
1762 if (this != Identity(phase)) {
1763 return nullptr;
1764 }
1765
1766 // Select Region to split through.
1767 Node* region;
1768 DomResult dom_result = DomResult::Dominate;
1769 if (!base_is_phi) {
1770 assert(mem->is_Phi(), "sanity");
1771 region = mem->in(0);
1772 // Skip if the region dominates some control edge of the address.
1773 // We will check `dom_result` later.
1774 dom_result = MemNode::maybe_all_controls_dominate(address, region);
1775 } else if (!mem->is_Phi()) {
1776 assert(base_is_phi, "sanity");
1777 region = base->in(0);
1778 // Skip if the region dominates some control edge of the memory.
1779 // We will check `dom_result` later.
1780 dom_result = MemNode::maybe_all_controls_dominate(mem, region);
1781 } else if (base->in(0) != mem->in(0)) {
1782 assert(base_is_phi && mem->is_Phi(), "sanity");
1783 dom_result = MemNode::maybe_all_controls_dominate(mem, base->in(0));
1784 if (dom_result == DomResult::Dominate) {
1785 region = base->in(0);
1786 } else {
1787 dom_result = MemNode::maybe_all_controls_dominate(address, mem->in(0));
1788 if (dom_result == DomResult::Dominate) {
1789 region = mem->in(0);
1790 }
1791 // Otherwise we encountered a complex graph.
1792 }
1793 } else {
1794 assert(base->in(0) == mem->in(0), "sanity");
1795 region = mem->in(0);
1796 }
1797
1798 PhaseIterGVN* igvn = phase->is_IterGVN();
1799 if (dom_result != DomResult::Dominate) {
1800 if (dom_result == DomResult::EncounteredDeadCode) {
1801 // There is some dead code which eventually will be removed in IGVN.
1802 // Once this is the case, we get an unambiguous dominance result.
1803 // Push the node to the worklist again until the dead code is removed.
1804 igvn->_worklist.push(this);
1805 }
1806 return nullptr;
1807 }
1808
1809 Node* phi = nullptr;
1810 const Type* this_type = this->bottom_type();
1811 if (t_oop != nullptr && (t_oop->is_known_instance_field() || load_boxed_values)) {
1812 int this_index = C->get_alias_index(t_oop);
1813 int this_offset = t_oop->offset();
1814 int this_iid = t_oop->is_known_instance_field() ? t_oop->instance_id() : base->_idx;
1815 phi = new PhiNode(region, this_type, nullptr, mem->_idx, this_iid, this_index, this_offset);
1816 } else if (ignore_missing_instance_id) {
1817 phi = new PhiNode(region, this_type, nullptr, mem->_idx);
1818 } else {
1819 return nullptr;
1820 }
1821
1822 for (uint i = 1; i < region->req(); i++) {
1823 Node* x;
1824 Node* the_clone = nullptr;
1825 Node* in = region->in(i);
1826 if (region->is_CountedLoop() && region->as_Loop()->is_strip_mined() && i == LoopNode::EntryControl &&
1827 in != nullptr && in->is_OuterStripMinedLoop()) {
1828 // No node should go in the outer strip mined loop
1829 in = in->in(LoopNode::EntryControl);
1830 }
1831 if (in == nullptr || in == C->top()) {
1832 x = C->top(); // Dead path? Use a dead data op
1833 } else {
1834 x = this->clone(); // Else clone up the data op
1835 the_clone = x; // Remember for possible deletion.
1836 // Alter data node to use pre-phi inputs
1837 if (this->in(0) == region) {
1838 x->set_req(0, in);
1839 } else {
1840 x->set_req(0, nullptr);
1841 }
1842 if (mem->is_Phi() && (mem->in(0) == region)) {
1843 x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone.
1844 }
1845 if (address->is_Phi() && address->in(0) == region) {
1846 x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone
1847 }
1848 if (base_is_phi && (base->in(0) == region)) {
1849 Node* base_x = base->in(i); // Clone address for loads from boxed objects.
1850 Node* adr_x = phase->transform(new AddPNode(base_x,base_x,address->in(AddPNode::Offset)));
1851 x->set_req(Address, adr_x);
1852 }
1853 }
1854 // Check for a 'win' on some paths
1855 const Type *t = x->Value(igvn);
1856
1857 bool singleton = t->singleton();
1858
1859 // See comments in PhaseIdealLoop::split_thru_phi().
1860 if (singleton && t == Type::TOP) {
1861 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1862 }
1863
1864 if (singleton) {
1865 x = igvn->makecon(t);
1866 } else {
1867 // We now call Identity to try to simplify the cloned node.
1868 // Note that some Identity methods call phase->type(this).
1869 // Make sure that the type array is big enough for
1870 // our new node, even though we may throw the node away.
1871 // (This tweaking with igvn only works because x is a new node.)
1872 igvn->set_type(x, t);
1873 // If x is a TypeNode, capture any more-precise type permanently into Node
1874 // otherwise it will be not updated during igvn->transform since
1875 // igvn->type(x) is set to x->Value() already.
1876 x->raise_bottom_type(t);
1877 Node* y = x->Identity(igvn);
1878 if (y != x) {
1879 x = y;
1880 } else {
1881 y = igvn->hash_find_insert(x);
1882 if (y) {
1883 x = y;
1884 } else {
1885 // Else x is a new node we are keeping
1886 // We do not need register_new_node_with_optimizer
1887 // because set_type has already been called.
1888 igvn->_worklist.push(x);
1889 }
1890 }
1891 }
1892 if (x != the_clone && the_clone != nullptr) {
1893 igvn->remove_dead_node(the_clone);
1894 }
1895 phi->set_req(i, x);
1896 }
1897 // Record Phi
1898 igvn->register_new_node_with_optimizer(phi);
1899 return phi;
1900 }
1901
1902 AllocateNode* LoadNode::is_new_object_mark_load() const {
1903 if (Opcode() == Op_LoadX) {
1904 Node* address = in(MemNode::Address);
1905 AllocateNode* alloc = AllocateNode::Ideal_allocation(address);
1906 Node* mem = in(MemNode::Memory);
1907 if (alloc != nullptr && mem->is_Proj() &&
1908 mem->in(0) != nullptr &&
1909 mem->in(0) == alloc->initialization() &&
1910 alloc->initialization()->proj_out_or_null(0) != nullptr) {
1911 return alloc;
1912 }
1913 }
1914 return nullptr;
1915 }
1916
1917
1918 //------------------------------Ideal------------------------------------------
1919 // If the load is from Field memory and the pointer is non-null, it might be possible to
1920 // zero out the control input.
1921 // If the offset is constant and the base is an object allocation,
1922 // try to hook me up to the exact initializing store.
1923 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1924 if (has_pinned_control_dependency()) {
1925 return nullptr;
1926 }
1927 Node* p = MemNode::Ideal_common(phase, can_reshape);
1928 if (p) return (p == NodeSentinel) ? nullptr : p;
1929
1930 Node* ctrl = in(MemNode::Control);
1931 Node* address = in(MemNode::Address);
1932
1933 bool addr_mark = ((phase->type(address)->isa_oopptr() || phase->type(address)->isa_narrowoop()) &&
1934 phase->type(address)->is_ptr()->offset() == oopDesc::mark_offset_in_bytes());
1935
1936 // Skip up past a SafePoint control. Cannot do this for Stores because
1937 // pointer stores & cardmarks must stay on the same side of a SafePoint.
1938 if( ctrl != nullptr && ctrl->Opcode() == Op_SafePoint &&
1939 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw &&
1940 !addr_mark &&
1941 (depends_only_on_test() || has_unknown_control_dependency())) {
1942 ctrl = ctrl->in(0);
1943 set_req(MemNode::Control,ctrl);
1944 return this;
1945 }
1946
1947 intptr_t ignore = 0;
1948 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1949 if (base != nullptr
1950 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
1951 // Check for useless control edge in some common special cases
1952 if (in(MemNode::Control) != nullptr
1953 && can_remove_control()
1954 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1955 && all_controls_dominate(base, phase->C->start())) {
1956 // A method-invariant, non-null address (constant or 'this' argument).
1957 set_req(MemNode::Control, nullptr);
1958 return this;
1959 }
1960 }
1961
1962 Node* mem = in(MemNode::Memory);
1963 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1964
1965 if (can_reshape && (addr_t != nullptr)) {
1966 // try to optimize our memory input
1967 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase);
1968 if (opt_mem != mem) {
1969 set_req_X(MemNode::Memory, opt_mem, phase);
1970 if (phase->type( opt_mem ) == Type::TOP) return nullptr;
1971 return this;
1972 }
1973 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1974 if ((t_oop != nullptr) &&
1975 (t_oop->is_known_instance_field() ||
1976 t_oop->is_ptr_to_boxed_value())) {
1977 PhaseIterGVN *igvn = phase->is_IterGVN();
1978 assert(igvn != nullptr, "must be PhaseIterGVN when can_reshape is true");
1979 if (igvn->_worklist.member(opt_mem)) {
1980 // Delay this transformation until memory Phi is processed.
1981 igvn->_worklist.push(this);
1982 return nullptr;
1983 }
1984 // Split instance field load through Phi.
1985 Node* result = split_through_phi(phase);
1986 if (result != nullptr) return result;
1987
1988 if (t_oop->is_ptr_to_boxed_value()) {
1989 Node* result = eliminate_autobox(igvn);
1990 if (result != nullptr) return result;
1991 }
1992 }
1993 }
1994
1995 // Is there a dominating load that loads the same value? Leave
1996 // anything that is not a load of a field/array element (like
1997 // barriers etc.) alone
1998 if (in(0) != nullptr && !adr_type()->isa_rawptr() && can_reshape) {
1999 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) {
2000 Node *use = mem->fast_out(i);
2001 if (use != this &&
2002 use->Opcode() == Opcode() &&
2003 use->in(0) != nullptr &&
2004 use->in(0) != in(0) &&
2005 use->in(Address) == in(Address)) {
2006 Node* ctl = in(0);
2007 for (int i = 0; i < 10 && ctl != nullptr; i++) {
2008 ctl = IfNode::up_one_dom(ctl);
2009 if (ctl == use->in(0)) {
2010 set_req(0, use->in(0));
2011 return this;
2012 }
2013 }
2014 }
2015 }
2016 }
2017
2018 // Check for prior store with a different base or offset; make Load
2019 // independent. Skip through any number of them. Bail out if the stores
2020 // are in an endless dead cycle and report no progress. This is a key
2021 // transform for Reflection. However, if after skipping through the Stores
2022 // we can't then fold up against a prior store do NOT do the transform as
2023 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
2024 // array memory alive twice: once for the hoisted Load and again after the
2025 // bypassed Store. This situation only works if EVERYBODY who does
2026 // anti-dependence work knows how to bypass. I.e. we need all
2027 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
2028 // the alias index stuff. So instead, peek through Stores and IFF we can
2029 // fold up, do so.
2030 Node* prev_mem = find_previous_store(phase);
2031 if (prev_mem != nullptr && prev_mem->is_top()) {
2032 // find_previous_store returns top when the access is dead
2033 return prev_mem;
2034 }
2035 if (prev_mem != nullptr) {
2036 Node* value = can_see_arraycopy_value(prev_mem, phase);
2037 if (value != nullptr) {
2038 return value;
2039 }
2040 }
2041 // Steps (a), (b): Walk past independent stores to find an exact match.
2042 if (prev_mem != nullptr && prev_mem != in(MemNode::Memory)) {
2043 // (c) See if we can fold up on the spot, but don't fold up here.
2044 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
2045 // just return a prior value, which is done by Identity calls.
2046 if (can_see_stored_value(prev_mem, phase)) {
2047 // Make ready for step (d):
2048 set_req_X(MemNode::Memory, prev_mem, phase);
2049 return this;
2050 }
2051 }
2052
2053 if (!can_reshape) {
2054 phase->record_for_igvn(this);
2055 }
2056
2057 return nullptr;
2058 }
2059
2060 // Helper to recognize certain Klass fields which are invariant across
2061 // some group of array types (e.g., int[] or all T[] where T < Object).
2062 const Type*
2063 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
2064 ciKlass* klass) const {
2065 assert(!UseCompactObjectHeaders ||
2066 AOTCodeCache::is_on_for_dump() ||
2067 tkls->offset() != in_bytes(Klass::prototype_header_offset()),
2068 "must not happen");
2069
2070 if (tkls->isa_instklassptr() && tkls->offset() == in_bytes(InstanceKlass::access_flags_offset())) {
2071 // The field is InstanceKlass::_access_flags. Return its (constant) value.
2072 assert(Opcode() == Op_LoadUS, "must load an unsigned short from _access_flags");
2073 ciInstanceKlass* iklass = tkls->is_instklassptr()->instance_klass();
2074 return TypeInt::make(iklass->access_flags());
2075 }
2076 if (tkls->offset() == in_bytes(Klass::misc_flags_offset())) {
2077 // The field is Klass::_misc_flags. Return its (constant) value.
2078 assert(Opcode() == Op_LoadUB, "must load an unsigned byte from _misc_flags");
2079 return TypeInt::make(klass->misc_flags());
2080 }
2081 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) {
2082 // The field is Klass::_layout_helper. Return its constant value if known.
2083 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
2084 return TypeInt::make(klass->layout_helper());
2085 }
2086
2087 // No match.
2088 return nullptr;
2089 }
2090
2091 //------------------------------Value-----------------------------------------
2092 const Type* LoadNode::Value(PhaseGVN* phase) const {
2093 // Either input is TOP ==> the result is TOP
2094 Node* mem = in(MemNode::Memory);
2095 const Type *t1 = phase->type(mem);
2096 if (t1 == Type::TOP) return Type::TOP;
2097 Node* adr = in(MemNode::Address);
2098 const TypePtr* tp = phase->type(adr)->isa_ptr();
2099 if (tp == nullptr || tp->empty()) return Type::TOP;
2100 int off = tp->offset();
2101 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
2102 Compile* C = phase->C;
2103
2104 // If load can see a previous constant store, use that.
2105 Node* value = can_see_stored_value(mem, phase);
2106 if (value != nullptr && value->is_Con()) {
2107 assert(value->bottom_type()->higher_equal(_type), "sanity");
2108 return value->bottom_type();
2109 }
2110
2111 // Try to guess loaded type from pointer type
2112 if (tp->isa_aryptr()) {
2113 const TypeAryPtr* ary = tp->is_aryptr();
2114 const Type* t = ary->elem();
2115
2116 // Determine whether the reference is beyond the header or not, by comparing
2117 // the offset against the offset of the start of the array's data.
2118 // Different array types begin at slightly different offsets (12 vs. 16).
2119 // We choose T_BYTE as an example base type that is least restrictive
2120 // as to alignment, which will therefore produce the smallest
2121 // possible base offset.
2122 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
2123 const bool off_beyond_header = (off >= min_base_off);
2124
2125 // Try to constant-fold a stable array element.
2126 if (FoldStableValues && !is_mismatched_access() && ary->is_stable()) {
2127 // Make sure the reference is not into the header and the offset is constant
2128 ciObject* aobj = ary->const_oop();
2129 if (aobj != nullptr && off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) {
2130 int stable_dimension = (ary->stable_dimension() > 0 ? ary->stable_dimension() - 1 : 0);
2131 const Type* con_type = Type::make_constant_from_array_element(aobj->as_array(), off,
2132 stable_dimension,
2133 value_basic_type(), is_unsigned());
2134 if (con_type != nullptr) {
2135 return con_type;
2136 }
2137 }
2138 }
2139
2140 // Don't do this for integer types. There is only potential profit if
2141 // the element type t is lower than _type; that is, for int types, if _type is
2142 // more restrictive than t. This only happens here if one is short and the other
2143 // char (both 16 bits), and in those cases we've made an intentional decision
2144 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
2145 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
2146 //
2147 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
2148 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
2149 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
2150 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
2151 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
2152 // In fact, that could have been the original type of p1, and p1 could have
2153 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
2154 // expression (LShiftL quux 3) independently optimized to the constant 8.
2155 if ((t->isa_int() == nullptr) && (t->isa_long() == nullptr)
2156 && (_type->isa_vect() == nullptr)
2157 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
2158 // t might actually be lower than _type, if _type is a unique
2159 // concrete subclass of abstract class t.
2160 if (off_beyond_header || off == Type::OffsetBot) { // is the offset beyond the header?
2161 const Type* jt = t->join_speculative(_type);
2162 // In any case, do not allow the join, per se, to empty out the type.
2163 if (jt->empty() && !t->empty()) {
2164 // This can happen if a interface-typed array narrows to a class type.
2165 jt = _type;
2166 }
2167 #ifdef ASSERT
2168 if (phase->C->eliminate_boxing() && adr->is_AddP()) {
2169 // The pointers in the autobox arrays are always non-null
2170 Node* base = adr->in(AddPNode::Base);
2171 if ((base != nullptr) && base->is_DecodeN()) {
2172 // Get LoadN node which loads IntegerCache.cache field
2173 base = base->in(1);
2174 }
2175 if ((base != nullptr) && base->is_Con()) {
2176 const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr();
2177 if ((base_type != nullptr) && base_type->is_autobox_cache()) {
2178 // It could be narrow oop
2179 assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity");
2180 }
2181 }
2182 }
2183 #endif
2184 return jt;
2185 }
2186 }
2187 } else if (tp->base() == Type::InstPtr) {
2188 assert( off != Type::OffsetBot ||
2189 // arrays can be cast to Objects
2190 !tp->isa_instptr() ||
2191 tp->is_instptr()->instance_klass()->is_java_lang_Object() ||
2192 // unsafe field access may not have a constant offset
2193 C->has_unsafe_access(),
2194 "Field accesses must be precise" );
2195 // For oop loads, we expect the _type to be precise.
2196
2197 // Optimize loads from constant fields.
2198 const TypeInstPtr* tinst = tp->is_instptr();
2199 ciObject* const_oop = tinst->const_oop();
2200 if (!is_mismatched_access() && off != Type::OffsetBot && const_oop != nullptr && const_oop->is_instance()) {
2201 const Type* con_type = Type::make_constant_from_field(const_oop->as_instance(), off, is_unsigned(), value_basic_type());
2202 if (con_type != nullptr) {
2203 return con_type;
2204 }
2205 }
2206 } else if (tp->base() == Type::KlassPtr || tp->base() == Type::InstKlassPtr || tp->base() == Type::AryKlassPtr) {
2207 assert(off != Type::OffsetBot ||
2208 !tp->isa_instklassptr() ||
2209 // arrays can be cast to Objects
2210 tp->isa_instklassptr()->instance_klass()->is_java_lang_Object() ||
2211 // also allow array-loading from the primary supertype
2212 // array during subtype checks
2213 Opcode() == Op_LoadKlass,
2214 "Field accesses must be precise");
2215 // For klass/static loads, we expect the _type to be precise
2216 } else if (tp->base() == Type::RawPtr && adr->is_Load() && off == 0) {
2217 /* With mirrors being an indirect in the Klass*
2218 * the VM is now using two loads. LoadKlass(LoadP(LoadP(Klass, mirror_offset), zero_offset))
2219 * The LoadP from the Klass has a RawPtr type (see LibraryCallKit::load_mirror_from_klass).
2220 *
2221 * So check the type and klass of the node before the LoadP.
2222 */
2223 Node* adr2 = adr->in(MemNode::Address);
2224 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2225 if (tkls != nullptr && !StressReflectiveCode) {
2226 if (tkls->is_loaded() && tkls->klass_is_exact() && tkls->offset() == in_bytes(Klass::java_mirror_offset())) {
2227 ciKlass* klass = tkls->exact_klass();
2228 assert(adr->Opcode() == Op_LoadP, "must load an oop from _java_mirror");
2229 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
2230 return TypeInstPtr::make(klass->java_mirror());
2231 }
2232 }
2233 }
2234
2235 const TypeKlassPtr *tkls = tp->isa_klassptr();
2236 if (tkls != nullptr) {
2237 if (tkls->is_loaded() && tkls->klass_is_exact()) {
2238 ciKlass* klass = tkls->exact_klass();
2239 // We are loading a field from a Klass metaobject whose identity
2240 // is known at compile time (the type is "exact" or "precise").
2241 // Check for fields we know are maintained as constants by the VM.
2242 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) {
2243 // The field is Klass::_super_check_offset. Return its (constant) value.
2244 // (Folds up type checking code.)
2245 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
2246 return TypeInt::make(klass->super_check_offset());
2247 }
2248 // Class encoding in prototype header may change between runs.
2249 // Force loading prototype header when AOT code is generated.
2250 if (UseCompactObjectHeaders && !AOTCodeCache::is_on_for_dump()) {
2251 if (tkls->offset() == in_bytes(Klass::prototype_header_offset())) {
2252 // The field is Klass::_prototype_header. Return its (constant) value.
2253 assert(this->Opcode() == Op_LoadX, "must load a proper type from _prototype_header");
2254 return TypeX::make(klass->prototype_header());
2255 }
2256 }
2257 // Compute index into primary_supers array
2258 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
2259 // Check for overflowing; use unsigned compare to handle the negative case.
2260 if( depth < ciKlass::primary_super_limit() ) {
2261 // The field is an element of Klass::_primary_supers. Return its (constant) value.
2262 // (Folds up type checking code.)
2263 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
2264 ciKlass *ss = klass->super_of_depth(depth);
2265 return ss ? TypeKlassPtr::make(ss, Type::trust_interfaces) : TypePtr::NULL_PTR;
2266 }
2267 const Type* aift = load_array_final_field(tkls, klass);
2268 if (aift != nullptr) return aift;
2269 }
2270
2271 // We can still check if we are loading from the primary_supers array at a
2272 // shallow enough depth. Even though the klass is not exact, entries less
2273 // than or equal to its super depth are correct.
2274 if (tkls->is_loaded()) {
2275 ciKlass* klass = nullptr;
2276 if (tkls->isa_instklassptr()) {
2277 klass = tkls->is_instklassptr()->instance_klass();
2278 } else {
2279 int dims;
2280 const Type* inner = tkls->is_aryklassptr()->base_element_type(dims);
2281 if (inner->isa_instklassptr()) {
2282 klass = inner->is_instklassptr()->instance_klass();
2283 klass = ciObjArrayKlass::make(klass, dims);
2284 }
2285 }
2286 if (klass != nullptr) {
2287 // Compute index into primary_supers array
2288 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
2289 // Check for overflowing; use unsigned compare to handle the negative case.
2290 if (depth < ciKlass::primary_super_limit() &&
2291 depth <= klass->super_depth()) { // allow self-depth checks to handle self-check case
2292 // The field is an element of Klass::_primary_supers. Return its (constant) value.
2293 // (Folds up type checking code.)
2294 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
2295 ciKlass *ss = klass->super_of_depth(depth);
2296 return ss ? TypeKlassPtr::make(ss, Type::trust_interfaces) : TypePtr::NULL_PTR;
2297 }
2298 }
2299 }
2300
2301 // If the type is enough to determine that the thing is not an array,
2302 // we can give the layout_helper a positive interval type.
2303 // This will help short-circuit some reflective code.
2304 if (tkls->offset() == in_bytes(Klass::layout_helper_offset()) &&
2305 tkls->isa_instklassptr() && // not directly typed as an array
2306 !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
2307 ) {
2308 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
2309 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
2310 // The key property of this type is that it folds up tests
2311 // for array-ness, since it proves that the layout_helper is positive.
2312 // Thus, a generic value like the basic object layout helper works fine.
2313 return TypeInt::make(min_size, max_jint, Type::WidenMin);
2314 }
2315 }
2316
2317 // If we are loading from a freshly-allocated object/array, produce a zero.
2318 // Things to check:
2319 // 1. Load is beyond the header: headers are not guaranteed to be zero
2320 // 2. Load is not vectorized: vectors have no zero constant
2321 // 3. Load has no matching store, i.e. the input is the initial memory state
2322 const TypeOopPtr* tinst = tp->isa_oopptr();
2323 bool is_not_header = (tinst != nullptr) && tinst->is_known_instance_field();
2324 bool is_not_vect = (_type->isa_vect() == nullptr);
2325 if (is_not_header && is_not_vect) {
2326 Node* mem = in(MemNode::Memory);
2327 if (mem->is_Parm() && mem->in(0)->is_Start()) {
2328 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
2329 return Type::get_zero_type(_type->basic_type());
2330 }
2331 }
2332
2333 if (!UseCompactObjectHeaders) {
2334 Node* alloc = is_new_object_mark_load();
2335 if (alloc != nullptr) {
2336 return TypeX::make(markWord::prototype().value());
2337 }
2338 }
2339
2340 return _type;
2341 }
2342
2343 //------------------------------match_edge-------------------------------------
2344 // Do we Match on this edge index or not? Match only the address.
2345 uint LoadNode::match_edge(uint idx) const {
2346 return idx == MemNode::Address;
2347 }
2348
2349 //--------------------------LoadBNode::Ideal--------------------------------------
2350 //
2351 // If the previous store is to the same address as this load,
2352 // and the value stored was larger than a byte, replace this load
2353 // with the value stored truncated to a byte. If no truncation is
2354 // needed, the replacement is done in LoadNode::Identity().
2355 //
2356 Node* LoadBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2357 Node* mem = in(MemNode::Memory);
2358 Node* value = can_see_stored_value(mem,phase);
2359 if (value != nullptr) {
2360 Node* narrow = Compile::narrow_value(T_BYTE, value, _type, phase, false);
2361 if (narrow != value) {
2362 return narrow;
2363 }
2364 }
2365 // Identity call will handle the case where truncation is not needed.
2366 return LoadNode::Ideal(phase, can_reshape);
2367 }
2368
2369 const Type* LoadBNode::Value(PhaseGVN* phase) const {
2370 Node* mem = in(MemNode::Memory);
2371 Node* value = can_see_stored_value(mem,phase);
2372 if (value != nullptr && value->is_Con() &&
2373 !value->bottom_type()->higher_equal(_type)) {
2374 // If the input to the store does not fit with the load's result type,
2375 // it must be truncated. We can't delay until Ideal call since
2376 // a singleton Value is needed for split_thru_phi optimization.
2377 int con = value->get_int();
2378 return TypeInt::make((con << 24) >> 24);
2379 }
2380 return LoadNode::Value(phase);
2381 }
2382
2383 //--------------------------LoadUBNode::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* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2391 Node* mem = in(MemNode::Memory);
2392 Node* value = can_see_stored_value(mem, phase);
2393 if (value != nullptr) {
2394 Node* narrow = Compile::narrow_value(T_BOOLEAN, 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* LoadUBNode::Value(PhaseGVN* phase) const {
2404 Node* mem = in(MemNode::Memory);
2405 Node* value = can_see_stored_value(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 & 0xFF);
2413 }
2414 return LoadNode::Value(phase);
2415 }
2416
2417 //--------------------------LoadUSNode::Ideal-------------------------------------
2418 //
2419 // If the previous store is to the same address as this load,
2420 // and the value stored was larger than a char, replace this load
2421 // with the value stored truncated to a char. If no truncation is
2422 // needed, the replacement is done in LoadNode::Identity().
2423 //
2424 Node* LoadUSNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2425 Node* mem = in(MemNode::Memory);
2426 Node* value = can_see_stored_value(mem,phase);
2427 if (value != nullptr) {
2428 Node* narrow = Compile::narrow_value(T_CHAR, 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* LoadUSNode::Value(PhaseGVN* phase) const {
2438 Node* mem = in(MemNode::Memory);
2439 Node* value = can_see_stored_value(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 & 0xFFFF);
2447 }
2448 return LoadNode::Value(phase);
2449 }
2450
2451 //--------------------------LoadSNode::Ideal--------------------------------------
2452 //
2453 // If the previous store is to the same address as this load,
2454 // and the value stored was larger than a short, replace this load
2455 // with the value stored truncated to a short. If no truncation is
2456 // needed, the replacement is done in LoadNode::Identity().
2457 //
2458 Node* LoadSNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2459 Node* mem = in(MemNode::Memory);
2460 Node* value = can_see_stored_value(mem,phase);
2461 if (value != nullptr) {
2462 Node* narrow = Compile::narrow_value(T_SHORT, 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* LoadSNode::Value(PhaseGVN* phase) const {
2472 Node* mem = in(MemNode::Memory);
2473 Node* value = can_see_stored_value(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 << 16) >> 16);
2481 }
2482 return LoadNode::Value(phase);
2483 }
2484
2485 //=============================================================================
2486 //----------------------------LoadKlassNode::make------------------------------
2487 // Polymorphic factory method:
2488 Node* LoadKlassNode::make(PhaseGVN& gvn, Node* mem, Node* adr, const TypePtr* at, const TypeKlassPtr* tk) {
2489 // sanity check the alias category against the created node type
2490 const TypePtr* adr_type = adr->bottom_type()->isa_ptr();
2491 assert(adr_type != nullptr, "expecting TypeKlassPtr");
2492 #ifdef _LP64
2493 if (adr_type->is_ptr_to_narrowklass()) {
2494 assert(UseCompressedClassPointers, "no compressed klasses");
2495 Node* load_klass = gvn.transform(new LoadNKlassNode(mem, adr, at, tk->make_narrowklass(), MemNode::unordered));
2496 return new DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr());
2497 }
2498 #endif
2499 assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
2500 return new LoadKlassNode(mem, adr, at, tk, MemNode::unordered);
2501 }
2502
2503 //------------------------------Value------------------------------------------
2504 const Type* LoadKlassNode::Value(PhaseGVN* phase) const {
2505 return klass_value_common(phase);
2506 }
2507
2508 const Type* LoadNode::klass_value_common(PhaseGVN* phase) const {
2509 // Either input is TOP ==> the result is TOP
2510 const Type *t1 = phase->type( in(MemNode::Memory) );
2511 if (t1 == Type::TOP) return Type::TOP;
2512 Node *adr = in(MemNode::Address);
2513 const Type *t2 = phase->type( adr );
2514 if (t2 == Type::TOP) return Type::TOP;
2515 const TypePtr *tp = t2->is_ptr();
2516 if (TypePtr::above_centerline(tp->ptr()) ||
2517 tp->ptr() == TypePtr::Null) return Type::TOP;
2518
2519 // Return a more precise klass, if possible
2520 const TypeInstPtr *tinst = tp->isa_instptr();
2521 if (tinst != nullptr) {
2522 ciInstanceKlass* ik = tinst->instance_klass();
2523 int offset = tinst->offset();
2524 if (ik == phase->C->env()->Class_klass()
2525 && (offset == java_lang_Class::klass_offset() ||
2526 offset == java_lang_Class::array_klass_offset())) {
2527 // We are loading a special hidden field from a Class mirror object,
2528 // the field which points to the VM's Klass metaobject.
2529 ciType* t = tinst->java_mirror_type();
2530 // java_mirror_type returns non-null for compile-time Class constants.
2531 if (t != nullptr) {
2532 // constant oop => constant klass
2533 if (offset == java_lang_Class::array_klass_offset()) {
2534 if (t->is_void()) {
2535 // We cannot create a void array. Since void is a primitive type return null
2536 // klass. Users of this result need to do a null check on the returned klass.
2537 return TypePtr::NULL_PTR;
2538 }
2539 return TypeKlassPtr::make(ciArrayKlass::make(t), Type::trust_interfaces);
2540 }
2541 if (!t->is_klass()) {
2542 // a primitive Class (e.g., int.class) has null for a klass field
2543 return TypePtr::NULL_PTR;
2544 }
2545 // Fold up the load of the hidden field
2546 return TypeKlassPtr::make(t->as_klass(), Type::trust_interfaces);
2547 }
2548 // non-constant mirror, so we can't tell what's going on
2549 }
2550 if (!tinst->is_loaded())
2551 return _type; // Bail out if not loaded
2552 if (offset == oopDesc::klass_offset_in_bytes()) {
2553 return tinst->as_klass_type(true);
2554 }
2555 }
2556
2557 // Check for loading klass from an array
2558 const TypeAryPtr *tary = tp->isa_aryptr();
2559 if (tary != nullptr &&
2560 tary->offset() == oopDesc::klass_offset_in_bytes()) {
2561 return tary->as_klass_type(true);
2562 }
2563
2564 // Check for loading klass from an array klass
2565 const TypeKlassPtr *tkls = tp->isa_klassptr();
2566 if (tkls != nullptr && !StressReflectiveCode) {
2567 if (!tkls->is_loaded())
2568 return _type; // Bail out if not loaded
2569 if (tkls->isa_aryklassptr() && tkls->is_aryklassptr()->elem()->isa_klassptr() &&
2570 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) {
2571 // // Always returning precise element type is incorrect,
2572 // // e.g., element type could be object and array may contain strings
2573 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
2574
2575 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
2576 // according to the element type's subclassing.
2577 return tkls->is_aryklassptr()->elem()->isa_klassptr()->cast_to_exactness(tkls->klass_is_exact());
2578 }
2579 if (tkls->isa_instklassptr() != nullptr && tkls->klass_is_exact() &&
2580 tkls->offset() == in_bytes(Klass::super_offset())) {
2581 ciKlass* sup = tkls->is_instklassptr()->instance_klass()->super();
2582 // The field is Klass::_super. Return its (constant) value.
2583 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
2584 return sup ? TypeKlassPtr::make(sup, Type::trust_interfaces) : TypePtr::NULL_PTR;
2585 }
2586 }
2587
2588 if (tkls != nullptr && !UseSecondarySupersCache
2589 && tkls->offset() == in_bytes(Klass::secondary_super_cache_offset())) {
2590 // Treat Klass::_secondary_super_cache as a constant when the cache is disabled.
2591 return TypePtr::NULL_PTR;
2592 }
2593
2594 // Bailout case
2595 return LoadNode::Value(phase);
2596 }
2597
2598 //------------------------------Identity---------------------------------------
2599 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
2600 // Also feed through the klass in Allocate(...klass...)._klass.
2601 Node* LoadKlassNode::Identity(PhaseGVN* phase) {
2602 return klass_identity_common(phase);
2603 }
2604
2605 Node* LoadNode::klass_identity_common(PhaseGVN* phase) {
2606 Node* x = LoadNode::Identity(phase);
2607 if (x != this) return x;
2608
2609 // Take apart the address into an oop and offset.
2610 // Return 'this' if we cannot.
2611 Node* adr = in(MemNode::Address);
2612 intptr_t offset = 0;
2613 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2614 if (base == nullptr) return this;
2615 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
2616 if (toop == nullptr) return this;
2617
2618 // Step over potential GC barrier for OopHandle resolve
2619 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
2620 if (bs->is_gc_barrier_node(base)) {
2621 base = bs->step_over_gc_barrier(base);
2622 }
2623
2624 // We can fetch the klass directly through an AllocateNode.
2625 // This works even if the klass is not constant (clone or newArray).
2626 if (offset == oopDesc::klass_offset_in_bytes()) {
2627 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
2628 if (allocated_klass != nullptr) {
2629 return allocated_klass;
2630 }
2631 }
2632
2633 // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*.
2634 // See inline_native_Class_query for occurrences of these patterns.
2635 // Java Example: x.getClass().isAssignableFrom(y)
2636 //
2637 // This improves reflective code, often making the Class
2638 // mirror go completely dead. (Current exception: Class
2639 // mirrors may appear in debug info, but we could clean them out by
2640 // introducing a new debug info operator for Klass.java_mirror).
2641
2642 if (toop->isa_instptr() && toop->is_instptr()->instance_klass() == phase->C->env()->Class_klass()
2643 && offset == java_lang_Class::klass_offset()) {
2644 if (base->is_Load()) {
2645 Node* base2 = base->in(MemNode::Address);
2646 if (base2->is_Load()) { /* direct load of a load which is the OopHandle */
2647 Node* adr2 = base2->in(MemNode::Address);
2648 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2649 if (tkls != nullptr && !tkls->empty()
2650 && (tkls->isa_instklassptr() || tkls->isa_aryklassptr())
2651 && adr2->is_AddP()
2652 ) {
2653 int mirror_field = in_bytes(Klass::java_mirror_offset());
2654 if (tkls->offset() == mirror_field) {
2655 #ifdef ASSERT
2656 const TypeKlassPtr* tkls2 = phase->type(adr2->in(AddPNode::Address))->is_klassptr();
2657 assert(tkls2->offset() == 0, "not a load of java_mirror");
2658 #endif
2659 assert(adr2->in(AddPNode::Base)->is_top(), "not an off heap load");
2660 assert(adr2->in(AddPNode::Offset)->find_intptr_t_con(-1) == in_bytes(Klass::java_mirror_offset()), "incorrect offset");
2661 return adr2->in(AddPNode::Address);
2662 }
2663 }
2664 }
2665 }
2666 }
2667
2668 return this;
2669 }
2670
2671 LoadNode* LoadNode::clone_pinned() const {
2672 LoadNode* ld = clone()->as_Load();
2673 ld->_control_dependency = UnknownControl;
2674 return ld;
2675 }
2676
2677 // Pin a LoadNode if it carries a dependency on its control input. There are cases when the node
2678 // does not actually have any dependency on its control input. For example, if we have a LoadNode
2679 // being used only outside a loop but it must be scheduled inside the loop, we can clone the node
2680 // for each of its use so that all the clones can be scheduled outside the loop. Then, to prevent
2681 // the clones from being GVN-ed again, we add a control input for each of them at the loop exit. In
2682 // those case, since there is not a dependency between the node and its control input, we do not
2683 // need to pin it.
2684 LoadNode* LoadNode::pin_node_under_control_impl() const {
2685 const TypePtr* adr_type = this->adr_type();
2686 if (adr_type != nullptr && adr_type->isa_aryptr()) {
2687 // Only array accesses have dependencies on their control input
2688 return clone_pinned();
2689 }
2690 return nullptr;
2691 }
2692
2693 //------------------------------Value------------------------------------------
2694 const Type* LoadNKlassNode::Value(PhaseGVN* phase) const {
2695 const Type *t = klass_value_common(phase);
2696 if (t == Type::TOP)
2697 return t;
2698
2699 return t->make_narrowklass();
2700 }
2701
2702 //------------------------------Identity---------------------------------------
2703 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
2704 // Also feed through the klass in Allocate(...klass...)._klass.
2705 Node* LoadNKlassNode::Identity(PhaseGVN* phase) {
2706 Node *x = klass_identity_common(phase);
2707
2708 const Type *t = phase->type( x );
2709 if( t == Type::TOP ) return x;
2710 if( t->isa_narrowklass()) return x;
2711 assert (!t->isa_narrowoop(), "no narrow oop here");
2712
2713 return phase->transform(new EncodePKlassNode(x, t->make_narrowklass()));
2714 }
2715
2716 //------------------------------Value-----------------------------------------
2717 const Type* LoadRangeNode::Value(PhaseGVN* phase) const {
2718 // Either input is TOP ==> the result is TOP
2719 const Type *t1 = phase->type( in(MemNode::Memory) );
2720 if( t1 == Type::TOP ) return Type::TOP;
2721 Node *adr = in(MemNode::Address);
2722 const Type *t2 = phase->type( adr );
2723 if( t2 == Type::TOP ) return Type::TOP;
2724 const TypePtr *tp = t2->is_ptr();
2725 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
2726 const TypeAryPtr *tap = tp->isa_aryptr();
2727 if( !tap ) return _type;
2728 return tap->size();
2729 }
2730
2731 //-------------------------------Ideal---------------------------------------
2732 // Feed through the length in AllocateArray(...length...)._length.
2733 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2734 Node* p = MemNode::Ideal_common(phase, can_reshape);
2735 if (p) return (p == NodeSentinel) ? nullptr : p;
2736
2737 // Take apart the address into an oop and offset.
2738 // Return 'this' if we cannot.
2739 Node* adr = in(MemNode::Address);
2740 intptr_t offset = 0;
2741 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2742 if (base == nullptr) return nullptr;
2743 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2744 if (tary == nullptr) return nullptr;
2745
2746 // We can fetch the length directly through an AllocateArrayNode.
2747 // This works even if the length is not constant (clone or newArray).
2748 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2749 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base);
2750 if (alloc != nullptr) {
2751 Node* allocated_length = alloc->Ideal_length();
2752 Node* len = alloc->make_ideal_length(tary, phase);
2753 if (allocated_length != len) {
2754 // New CastII improves on this.
2755 return len;
2756 }
2757 }
2758 }
2759
2760 return nullptr;
2761 }
2762
2763 //------------------------------Identity---------------------------------------
2764 // Feed through the length in AllocateArray(...length...)._length.
2765 Node* LoadRangeNode::Identity(PhaseGVN* phase) {
2766 Node* x = LoadINode::Identity(phase);
2767 if (x != this) return x;
2768
2769 // Take apart the address into an oop and offset.
2770 // Return 'this' if we cannot.
2771 Node* adr = in(MemNode::Address);
2772 intptr_t offset = 0;
2773 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2774 if (base == nullptr) return this;
2775 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2776 if (tary == nullptr) return this;
2777
2778 // We can fetch the length directly through an AllocateArrayNode.
2779 // This works even if the length is not constant (clone or newArray).
2780 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2781 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base);
2782 if (alloc != nullptr) {
2783 Node* allocated_length = alloc->Ideal_length();
2784 // Do not allow make_ideal_length to allocate a CastII node.
2785 Node* len = alloc->make_ideal_length(tary, phase, false);
2786 if (allocated_length == len) {
2787 // Return allocated_length only if it would not be improved by a CastII.
2788 return allocated_length;
2789 }
2790 }
2791 }
2792
2793 return this;
2794
2795 }
2796
2797 //=============================================================================
2798 //---------------------------StoreNode::make-----------------------------------
2799 // Polymorphic factory method:
2800 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) {
2801 assert((mo == unordered || mo == release), "unexpected");
2802 Compile* C = gvn.C;
2803 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");
2804 assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2805 ctl != nullptr, "raw memory operations should have control edge");
2806
2807 switch (bt) {
2808 case T_BOOLEAN: val = gvn.transform(new AndINode(val, gvn.intcon(0x1))); // Fall through to T_BYTE case
2809 case T_BYTE: return new StoreBNode(ctl, mem, adr, adr_type, val, mo);
2810 case T_INT: return new StoreINode(ctl, mem, adr, adr_type, val, mo);
2811 case T_CHAR:
2812 case T_SHORT: return new StoreCNode(ctl, mem, adr, adr_type, val, mo);
2813 case T_LONG: return new StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic_access);
2814 case T_FLOAT: return new StoreFNode(ctl, mem, adr, adr_type, val, mo);
2815 case T_DOUBLE: return new StoreDNode(ctl, mem, adr, adr_type, val, mo, require_atomic_access);
2816 case T_METADATA:
2817 case T_ADDRESS:
2818 case T_OBJECT:
2819 #ifdef _LP64
2820 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
2821 val = gvn.transform(new EncodePNode(val, val->bottom_type()->make_narrowoop()));
2822 return new StoreNNode(ctl, mem, adr, adr_type, val, mo);
2823 } else if (adr->bottom_type()->is_ptr_to_narrowklass() ||
2824 (UseCompressedClassPointers && val->bottom_type()->isa_klassptr() &&
2825 adr->bottom_type()->isa_rawptr())) {
2826 val = gvn.transform(new EncodePKlassNode(val, val->bottom_type()->make_narrowklass()));
2827 return new StoreNKlassNode(ctl, mem, adr, adr_type, val, mo);
2828 }
2829 #endif
2830 {
2831 return new StorePNode(ctl, mem, adr, adr_type, val, mo);
2832 }
2833 default:
2834 ShouldNotReachHere();
2835 return (StoreNode*)nullptr;
2836 }
2837 }
2838
2839 //--------------------------bottom_type----------------------------------------
2840 const Type *StoreNode::bottom_type() const {
2841 return Type::MEMORY;
2842 }
2843
2844 //------------------------------hash-------------------------------------------
2845 uint StoreNode::hash() const {
2846 // unroll addition of interesting fields
2847 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2848
2849 // Since they are not commoned, do not hash them:
2850 return NO_HASH;
2851 }
2852
2853 // Link together multiple stores (B/S/C/I) into a longer one.
2854 //
2855 // Example: _store = StoreB[i+3]
2856 //
2857 // RangeCheck[i+0] RangeCheck[i+0]
2858 // StoreB[i+0]
2859 // RangeCheck[i+3] RangeCheck[i+3]
2860 // StoreB[i+1] --> pass: fail:
2861 // StoreB[i+2] StoreI[i+0] StoreB[i+0]
2862 // StoreB[i+3]
2863 //
2864 // The 4 StoreB are merged into a single StoreI node. We have to be careful with RangeCheck[i+1]: before
2865 // the optimization, if this RangeCheck[i+1] fails, then we execute only StoreB[i+0], and then trap. After
2866 // the optimization, the new StoreI[i+0] is on the passing path of RangeCheck[i+3], and StoreB[i+0] on the
2867 // failing path.
2868 //
2869 // Note: For normal array stores, every store at first has a RangeCheck. But they can be removed with:
2870 // - RCE (RangeCheck Elimination): the RangeChecks in the loop are hoisted out and before the loop,
2871 // and possibly no RangeChecks remain between the stores.
2872 // - RangeCheck smearing: the earlier RangeChecks are adjusted such that they cover later RangeChecks,
2873 // and those later RangeChecks can be removed. Example:
2874 //
2875 // RangeCheck[i+0] RangeCheck[i+0] <- before first store
2876 // StoreB[i+0] StoreB[i+0] <- first store
2877 // RangeCheck[i+1] --> smeared --> RangeCheck[i+3] <- only RC between first and last store
2878 // StoreB[i+1] StoreB[i+1] <- second store
2879 // RangeCheck[i+2] --> removed
2880 // StoreB[i+2] StoreB[i+2]
2881 // RangeCheck[i+3] --> removed
2882 // StoreB[i+3] StoreB[i+3] <- last store
2883 //
2884 // Thus, it is a common pattern that between the first and last store in a chain
2885 // of adjacent stores there remains exactly one RangeCheck, located between the
2886 // first and the second store (e.g. RangeCheck[i+3]).
2887 //
2888 class MergePrimitiveStores : public StackObj {
2889 private:
2890 PhaseGVN* const _phase;
2891 StoreNode* const _store;
2892 // State machine with initial state Unknown
2893 // Allowed transitions:
2894 // Unknown -> Const
2895 // Unknown -> Platform
2896 // Unknown -> Reverse
2897 // Unknown -> NotAdjacent
2898 // Const -> Const
2899 // Const -> NotAdjacent
2900 // Platform -> Platform
2901 // Platform -> NotAdjacent
2902 // Reverse -> Reverse
2903 // Reverse -> NotAdjacent
2904 // NotAdjacent -> NotAdjacent
2905 enum ValueOrder : uint8_t {
2906 Unknown, // Initial state
2907 Const, // Input values are const
2908 Platform, // Platform order
2909 Reverse, // Reverse platform order
2910 NotAdjacent // Not adjacent
2911 };
2912 ValueOrder _value_order;
2913
2914 NOT_PRODUCT( const CHeapBitMap &_trace_tags; )
2915
2916 public:
2917 MergePrimitiveStores(PhaseGVN* phase, StoreNode* store) :
2918 _phase(phase), _store(store), _value_order(ValueOrder::Unknown)
2919 NOT_PRODUCT( COMMA _trace_tags(Compile::current()->directive()->trace_merge_stores_tags()) )
2920 {}
2921
2922 StoreNode* run();
2923
2924 private:
2925 bool is_compatible_store(const StoreNode* other_store) const;
2926 bool is_adjacent_pair(const StoreNode* use_store, const StoreNode* def_store) const;
2927 bool is_adjacent_input_pair(const Node* n1, const Node* n2, const int memory_size) const;
2928 static bool is_con_RShift(const Node* n, Node const*& base_out, jint& shift_out, PhaseGVN* phase);
2929 enum CFGStatus { SuccessNoRangeCheck, SuccessWithRangeCheck, Failure };
2930 static CFGStatus cfg_status_for_pair(const StoreNode* use_store, const StoreNode* def_store);
2931
2932 class Status {
2933 private:
2934 StoreNode* _found_store;
2935 bool _found_range_check;
2936
2937 Status(StoreNode* found_store, bool found_range_check)
2938 : _found_store(found_store), _found_range_check(found_range_check) {}
2939
2940 public:
2941 StoreNode* found_store() const { return _found_store; }
2942 bool found_range_check() const { return _found_range_check; }
2943 static Status make_failure() { return Status(nullptr, false); }
2944
2945 static Status make(StoreNode* found_store, const CFGStatus cfg_status) {
2946 if (cfg_status == CFGStatus::Failure) {
2947 return Status::make_failure();
2948 }
2949 return Status(found_store, cfg_status == CFGStatus::SuccessWithRangeCheck);
2950 }
2951
2952 #ifndef PRODUCT
2953 void print_on(outputStream* st) const {
2954 if (_found_store == nullptr) {
2955 st->print_cr("None");
2956 } else {
2957 st->print_cr("Found[%d %s, %s]", _found_store->_idx, _found_store->Name(),
2958 _found_range_check ? "RC" : "no-RC");
2959 }
2960 }
2961 #endif
2962 };
2963
2964 enum ValueOrder find_adjacent_input_value_order(const Node* n1, const Node* n2, const int memory_size) const;
2965 Status find_adjacent_use_store(const StoreNode* def_store) const;
2966 Status find_adjacent_def_store(const StoreNode* use_store) const;
2967 Status find_use_store(const StoreNode* def_store) const;
2968 Status find_def_store(const StoreNode* use_store) const;
2969 Status find_use_store_unidirectional(const StoreNode* def_store) const;
2970 Status find_def_store_unidirectional(const StoreNode* use_store) const;
2971
2972 void collect_merge_list(Node_List& merge_list) const;
2973 Node* make_merged_input_value(const Node_List& merge_list);
2974 StoreNode* make_merged_store(const Node_List& merge_list, Node* merged_input_value);
2975
2976 #ifndef PRODUCT
2977 // Access to TraceMergeStores tags
2978 bool is_trace(TraceMergeStores::Tag tag) const {
2979 return _trace_tags.at(tag);
2980 }
2981
2982 bool is_trace_basic() const {
2983 return is_trace(TraceMergeStores::Tag::BASIC);
2984 }
2985
2986 bool is_trace_pointer_parsing() const {
2987 return is_trace(TraceMergeStores::Tag::POINTER_PARSING);
2988 }
2989
2990 bool is_trace_pointer_aliasing() const {
2991 return is_trace(TraceMergeStores::Tag::POINTER_ALIASING);
2992 }
2993
2994 bool is_trace_pointer_adjacency() const {
2995 return is_trace(TraceMergeStores::Tag::POINTER_ADJACENCY);
2996 }
2997
2998 bool is_trace_success() const {
2999 return is_trace(TraceMergeStores::Tag::SUCCESS);
3000 }
3001 #endif
3002
3003 NOT_PRODUCT( void trace(const Node_List& merge_list, const Node* merged_input_value, const StoreNode* merged_store) const; )
3004 };
3005
3006 StoreNode* MergePrimitiveStores::run() {
3007 // Check for B/S/C/I
3008 int opc = _store->Opcode();
3009 if (opc != Op_StoreB && opc != Op_StoreC && opc != Op_StoreI) {
3010 return nullptr;
3011 }
3012
3013 NOT_PRODUCT( if (is_trace_basic()) { tty->print("[TraceMergeStores] MergePrimitiveStores::run: "); _store->dump(); })
3014
3015 // The _store must be the "last" store in a chain. If we find a use we could merge with
3016 // then that use or a store further down is the "last" store.
3017 Status status_use = find_adjacent_use_store(_store);
3018 NOT_PRODUCT( if (is_trace_basic()) { tty->print("[TraceMergeStores] expect no use: "); status_use.print_on(tty); })
3019 if (status_use.found_store() != nullptr) {
3020 return nullptr;
3021 }
3022
3023 // Check if we can merge with at least one def, so that we have at least 2 stores to merge.
3024 Status status_def = find_adjacent_def_store(_store);
3025 NOT_PRODUCT( if (is_trace_basic()) { tty->print("[TraceMergeStores] expect def: "); status_def.print_on(tty); })
3026 Node* def_store = status_def.found_store();
3027 if (def_store == nullptr) {
3028 return nullptr;
3029 }
3030
3031 // Initialize value order
3032 _value_order = find_adjacent_input_value_order(def_store->in(MemNode::ValueIn),
3033 _store->in(MemNode::ValueIn),
3034 _store->memory_size());
3035 assert(_value_order != ValueOrder::NotAdjacent && _value_order != ValueOrder::Unknown, "Order should be checked");
3036
3037 ResourceMark rm;
3038 Node_List merge_list;
3039 collect_merge_list(merge_list);
3040
3041 Node* merged_input_value = make_merged_input_value(merge_list);
3042 if (merged_input_value == nullptr) { return nullptr; }
3043
3044 StoreNode* merged_store = make_merged_store(merge_list, merged_input_value);
3045
3046 NOT_PRODUCT( if (is_trace_success()) { trace(merge_list, merged_input_value, merged_store); } )
3047
3048 return merged_store;
3049 }
3050
3051 // Check compatibility between _store and other_store.
3052 bool MergePrimitiveStores::is_compatible_store(const StoreNode* other_store) const {
3053 int opc = _store->Opcode();
3054 assert(opc == Op_StoreB || opc == Op_StoreC || opc == Op_StoreI, "precondition");
3055
3056 if (other_store == nullptr ||
3057 _store->Opcode() != other_store->Opcode()) {
3058 return false;
3059 }
3060
3061 return true;
3062 }
3063
3064 bool MergePrimitiveStores::is_adjacent_pair(const StoreNode* use_store, const StoreNode* def_store) const {
3065 if (!is_adjacent_input_pair(def_store->in(MemNode::ValueIn),
3066 use_store->in(MemNode::ValueIn),
3067 def_store->memory_size())) {
3068 return false;
3069 }
3070
3071 ResourceMark rm;
3072 #ifndef PRODUCT
3073 const TraceMemPointer trace(is_trace_pointer_parsing(),
3074 is_trace_pointer_aliasing(),
3075 is_trace_pointer_adjacency(),
3076 true);
3077 #endif
3078 const MemPointer pointer_use(use_store NOT_PRODUCT(COMMA trace));
3079 const MemPointer pointer_def(def_store NOT_PRODUCT(COMMA trace));
3080 return pointer_def.is_adjacent_to_and_before(pointer_use);
3081 }
3082
3083 // Check input values n1 and n2 can be merged and return the value order
3084 MergePrimitiveStores::ValueOrder MergePrimitiveStores::find_adjacent_input_value_order(const Node* n1, const Node* n2,
3085 const int memory_size) const {
3086 // Pattern: [n1 = ConI, n2 = ConI]
3087 if (n1->Opcode() == Op_ConI && n2->Opcode() == Op_ConI) {
3088 return ValueOrder::Const;
3089 }
3090
3091 Node const *base_n2;
3092 jint shift_n2;
3093 if (!is_con_RShift(n2, base_n2, shift_n2, _phase)) {
3094 return ValueOrder::NotAdjacent;
3095 }
3096 Node const *base_n1;
3097 jint shift_n1;
3098 if (!is_con_RShift(n1, base_n1, shift_n1, _phase)) {
3099 return ValueOrder::NotAdjacent;
3100 }
3101
3102 int bits_per_store = memory_size * 8;
3103 if (base_n1 != base_n2 ||
3104 abs(shift_n1 - shift_n2) != bits_per_store ||
3105 shift_n1 % bits_per_store != 0) {
3106 // Values are not adjacent
3107 return ValueOrder::NotAdjacent;
3108 }
3109
3110 // Detect value order
3111 #ifdef VM_LITTLE_ENDIAN
3112 return shift_n1 < shift_n2 ? ValueOrder::Platform // Pattern: [n1 = base >> shift, n2 = base >> (shift + memory_size)]
3113 : ValueOrder::Reverse; // Pattern: [n1 = base >> (shift + memory_size), n2 = base >> shift]
3114 #else
3115 return shift_n1 > shift_n2 ? ValueOrder::Platform // Pattern: [n1 = base >> (shift + memory_size), n2 = base >> shift]
3116 : ValueOrder::Reverse; // Pattern: [n1 = base >> shift, n2 = base >> (shift + memory_size)]
3117 #endif
3118 }
3119
3120 bool MergePrimitiveStores::is_adjacent_input_pair(const Node* n1, const Node* n2, const int memory_size) const {
3121 ValueOrder input_value_order = find_adjacent_input_value_order(n1, n2, memory_size);
3122
3123 switch (input_value_order) {
3124 case ValueOrder::NotAdjacent:
3125 return false;
3126 case ValueOrder::Reverse:
3127 if (memory_size != 1 ||
3128 !Matcher::match_rule_supported(Op_ReverseBytesS) ||
3129 !Matcher::match_rule_supported(Op_ReverseBytesI) ||
3130 !Matcher::match_rule_supported(Op_ReverseBytesL)) {
3131 // ReverseBytes are not supported by platform
3132 return false;
3133 }
3134 // fall-through.
3135 case ValueOrder::Const:
3136 case ValueOrder::Platform:
3137 if (_value_order == ValueOrder::Unknown) {
3138 // Initial state is Unknown, and we find a valid input value order
3139 return true;
3140 }
3141 // The value order can not be changed
3142 return _value_order == input_value_order;
3143 case ValueOrder::Unknown:
3144 default:
3145 ShouldNotReachHere();
3146 }
3147 return false;
3148 }
3149
3150 // Detect pattern: n = base_out >> shift_out
3151 bool MergePrimitiveStores::is_con_RShift(const Node* n, Node const*& base_out, jint& shift_out, PhaseGVN* phase) {
3152 assert(n != nullptr, "precondition");
3153
3154 int opc = n->Opcode();
3155 if (opc == Op_ConvL2I) {
3156 n = n->in(1);
3157 opc = n->Opcode();
3158 }
3159
3160 if ((opc == Op_RShiftI ||
3161 opc == Op_RShiftL ||
3162 opc == Op_URShiftI ||
3163 opc == Op_URShiftL) &&
3164 n->in(2)->is_ConI()) {
3165 base_out = n->in(1);
3166 shift_out = n->in(2)->get_int();
3167 // The shift must be positive:
3168 return shift_out >= 0;
3169 }
3170
3171 if (phase->type(n)->isa_int() != nullptr ||
3172 phase->type(n)->isa_long() != nullptr) {
3173 // (base >> 0)
3174 base_out = n;
3175 shift_out = 0;
3176 return true;
3177 }
3178 return false;
3179 }
3180
3181 // Check if there is nothing between the two stores, except optionally a RangeCheck leading to an uncommon trap.
3182 MergePrimitiveStores::CFGStatus MergePrimitiveStores::cfg_status_for_pair(const StoreNode* use_store, const StoreNode* def_store) {
3183 assert(use_store->in(MemNode::Memory) == def_store, "use-def relationship");
3184
3185 Node* ctrl_use = use_store->in(MemNode::Control);
3186 Node* ctrl_def = def_store->in(MemNode::Control);
3187 if (ctrl_use == nullptr || ctrl_def == nullptr) {
3188 return CFGStatus::Failure;
3189 }
3190
3191 if (ctrl_use == ctrl_def) {
3192 // Same ctrl -> no RangeCheck in between.
3193 // Check: use_store must be the only use of def_store.
3194 if (def_store->outcnt() > 1) {
3195 return CFGStatus::Failure;
3196 }
3197 return CFGStatus::SuccessNoRangeCheck;
3198 }
3199
3200 // Different ctrl -> could have RangeCheck in between.
3201 // Check: 1. def_store only has these uses: use_store and MergeMem for uncommon trap, and
3202 // 2. ctrl separated by RangeCheck.
3203 if (def_store->outcnt() != 2) {
3204 return CFGStatus::Failure; // Cannot have exactly these uses: use_store and MergeMem for uncommon trap.
3205 }
3206 int use_store_out_idx = def_store->raw_out(0) == use_store ? 0 : 1;
3207 Node* merge_mem = def_store->raw_out(1 - use_store_out_idx)->isa_MergeMem();
3208 if (merge_mem == nullptr ||
3209 merge_mem->outcnt() != 1) {
3210 return CFGStatus::Failure; // Does not have MergeMem for uncommon trap.
3211 }
3212 if (!ctrl_use->is_IfProj() ||
3213 !ctrl_use->in(0)->is_RangeCheck() ||
3214 ctrl_use->in(0)->outcnt() != 2) {
3215 return CFGStatus::Failure; // Not RangeCheck.
3216 }
3217 IfProjNode* other_proj = ctrl_use->as_IfProj()->other_if_proj();
3218 Node* trap = other_proj->is_uncommon_trap_proj(Deoptimization::Reason_range_check);
3219 if (trap != merge_mem->unique_out() ||
3220 ctrl_use->in(0)->in(0) != ctrl_def) {
3221 return CFGStatus::Failure; // Not RangeCheck with merge_mem leading to uncommon trap.
3222 }
3223
3224 return CFGStatus::SuccessWithRangeCheck;
3225 }
3226
3227 MergePrimitiveStores::Status MergePrimitiveStores::find_adjacent_use_store(const StoreNode* def_store) const {
3228 Status status_use = find_use_store(def_store);
3229 StoreNode* use_store = status_use.found_store();
3230 if (use_store != nullptr && !is_adjacent_pair(use_store, def_store)) {
3231 return Status::make_failure();
3232 }
3233 return status_use;
3234 }
3235
3236 MergePrimitiveStores::Status MergePrimitiveStores::find_adjacent_def_store(const StoreNode* use_store) const {
3237 Status status_def = find_def_store(use_store);
3238 StoreNode* def_store = status_def.found_store();
3239 if (def_store != nullptr && !is_adjacent_pair(use_store, def_store)) {
3240 return Status::make_failure();
3241 }
3242 return status_def;
3243 }
3244
3245 MergePrimitiveStores::Status MergePrimitiveStores::find_use_store(const StoreNode* def_store) const {
3246 Status status_use = find_use_store_unidirectional(def_store);
3247
3248 #ifdef ASSERT
3249 StoreNode* use_store = status_use.found_store();
3250 if (use_store != nullptr) {
3251 Status status_def = find_def_store_unidirectional(use_store);
3252 assert(status_def.found_store() == def_store &&
3253 status_def.found_range_check() == status_use.found_range_check(),
3254 "find_use_store and find_def_store must be symmetric");
3255 }
3256 #endif
3257
3258 return status_use;
3259 }
3260
3261 MergePrimitiveStores::Status MergePrimitiveStores::find_def_store(const StoreNode* use_store) const {
3262 Status status_def = find_def_store_unidirectional(use_store);
3263
3264 #ifdef ASSERT
3265 StoreNode* def_store = status_def.found_store();
3266 if (def_store != nullptr) {
3267 Status status_use = find_use_store_unidirectional(def_store);
3268 assert(status_use.found_store() == use_store &&
3269 status_use.found_range_check() == status_def.found_range_check(),
3270 "find_use_store and find_def_store must be symmetric");
3271 }
3272 #endif
3273
3274 return status_def;
3275 }
3276
3277 MergePrimitiveStores::Status MergePrimitiveStores::find_use_store_unidirectional(const StoreNode* def_store) const {
3278 assert(is_compatible_store(def_store), "precondition: must be compatible with _store");
3279
3280 for (DUIterator_Fast imax, i = def_store->fast_outs(imax); i < imax; i++) {
3281 StoreNode* use_store = def_store->fast_out(i)->isa_Store();
3282 if (is_compatible_store(use_store)) {
3283 return Status::make(use_store, cfg_status_for_pair(use_store, def_store));
3284 }
3285 }
3286
3287 return Status::make_failure();
3288 }
3289
3290 MergePrimitiveStores::Status MergePrimitiveStores::find_def_store_unidirectional(const StoreNode* use_store) const {
3291 assert(is_compatible_store(use_store), "precondition: must be compatible with _store");
3292
3293 StoreNode* def_store = use_store->in(MemNode::Memory)->isa_Store();
3294 if (!is_compatible_store(def_store)) {
3295 return Status::make_failure();
3296 }
3297
3298 return Status::make(def_store, cfg_status_for_pair(use_store, def_store));
3299 }
3300
3301 void MergePrimitiveStores::collect_merge_list(Node_List& merge_list) const {
3302 // The merged store can be at most 8 bytes.
3303 const uint merge_list_max_size = 8 / _store->memory_size();
3304 assert(merge_list_max_size >= 2 &&
3305 merge_list_max_size <= 8 &&
3306 is_power_of_2(merge_list_max_size),
3307 "must be 2, 4 or 8");
3308
3309 // Traverse up the chain of adjacent def stores.
3310 StoreNode* current = _store;
3311 merge_list.push(current);
3312 while (current != nullptr && merge_list.size() < merge_list_max_size) {
3313 Status status = find_adjacent_def_store(current);
3314 NOT_PRODUCT( if (is_trace_basic()) { tty->print("[TraceMergeStores] find def: "); status.print_on(tty); })
3315
3316 current = status.found_store();
3317 if (current != nullptr) {
3318 merge_list.push(current);
3319
3320 // We can have at most one RangeCheck.
3321 if (status.found_range_check()) {
3322 NOT_PRODUCT( if (is_trace_basic()) { tty->print_cr("[TraceMergeStores] found RangeCheck, stop traversal."); })
3323 break;
3324 }
3325 }
3326 }
3327
3328 NOT_PRODUCT( if (is_trace_basic()) { tty->print_cr("[TraceMergeStores] found:"); merge_list.dump(); })
3329
3330 // Truncate the merge_list to a power of 2.
3331 const uint pow2size = round_down_power_of_2(merge_list.size());
3332 assert(pow2size >= 2, "must be merging at least 2 stores");
3333 while (merge_list.size() > pow2size) { merge_list.pop(); }
3334
3335 NOT_PRODUCT( if (is_trace_basic()) { tty->print_cr("[TraceMergeStores] truncated:"); merge_list.dump(); })
3336 }
3337
3338 // Merge the input values of the smaller stores to a single larger input value.
3339 Node* MergePrimitiveStores::make_merged_input_value(const Node_List& merge_list) {
3340 int new_memory_size = _store->memory_size() * merge_list.size();
3341 Node* first = merge_list.at(merge_list.size()-1);
3342 Node* merged_input_value = nullptr;
3343 if (_store->in(MemNode::ValueIn)->Opcode() == Op_ConI) {
3344 assert(_value_order == ValueOrder::Const, "must match");
3345 // Pattern: [ConI, ConI, ...] -> new constant
3346 jlong con = 0;
3347 jlong bits_per_store = _store->memory_size() * 8;
3348 jlong mask = (((jlong)1) << bits_per_store) - 1;
3349 for (uint i = 0; i < merge_list.size(); i++) {
3350 jlong con_i = merge_list.at(i)->in(MemNode::ValueIn)->get_int();
3351 #ifdef VM_LITTLE_ENDIAN
3352 con = con << bits_per_store;
3353 con = con | (mask & con_i);
3354 #else // VM_LITTLE_ENDIAN
3355 con_i = (mask & con_i) << (i * bits_per_store);
3356 con = con | con_i;
3357 #endif // VM_LITTLE_ENDIAN
3358 }
3359 merged_input_value = _phase->longcon(con);
3360 } else {
3361 assert(_value_order == ValueOrder::Platform || _value_order == ValueOrder::Reverse, "must match");
3362 // Pattern: [base >> 24, base >> 16, base >> 8, base] -> base
3363 // | |
3364 // _store first
3365 //
3366 Node* hi = _store->in(MemNode::ValueIn);
3367 Node* lo = first->in(MemNode::ValueIn);
3368 #ifndef VM_LITTLE_ENDIAN
3369 // `_store` and `first` are swapped in the diagram above
3370 swap(hi, lo);
3371 #endif // !VM_LITTLE_ENDIAN
3372 if (_value_order == ValueOrder::Reverse) {
3373 swap(hi, lo);
3374 }
3375 Node const* hi_base;
3376 jint hi_shift;
3377 merged_input_value = lo;
3378 bool is_true = is_con_RShift(hi, hi_base, hi_shift, _phase);
3379 assert(is_true, "must detect con RShift");
3380 if (merged_input_value != hi_base && merged_input_value->Opcode() == Op_ConvL2I) {
3381 // look through
3382 merged_input_value = merged_input_value->in(1);
3383 }
3384 if (merged_input_value != hi_base) {
3385 // merged_input_value is not the base
3386 return nullptr;
3387 }
3388 }
3389
3390 if (_phase->type(merged_input_value)->isa_long() != nullptr && new_memory_size <= 4) {
3391 // Example:
3392 //
3393 // long base = ...;
3394 // a[0] = (byte)(base >> 0);
3395 // a[1] = (byte)(base >> 8);
3396 //
3397 merged_input_value = _phase->transform(new ConvL2INode(merged_input_value));
3398 }
3399
3400 assert((_phase->type(merged_input_value)->isa_int() != nullptr && new_memory_size <= 4) ||
3401 (_phase->type(merged_input_value)->isa_long() != nullptr && new_memory_size == 8),
3402 "merged_input_value is either int or long, and new_memory_size is small enough");
3403
3404 if (_value_order == ValueOrder::Reverse) {
3405 assert(_store->memory_size() == 1, "only implemented for bytes");
3406 if (new_memory_size == 8) {
3407 merged_input_value = _phase->transform(new ReverseBytesLNode(merged_input_value));
3408 } else if (new_memory_size == 4) {
3409 merged_input_value = _phase->transform(new ReverseBytesINode(merged_input_value));
3410 } else {
3411 assert(new_memory_size == 2, "sanity check");
3412 merged_input_value = _phase->transform(new ReverseBytesSNode(merged_input_value));
3413 }
3414 }
3415 return merged_input_value;
3416 }
3417
3418 // //
3419 // first_ctrl first_mem first_adr first_ctrl first_mem first_adr //
3420 // | | | | | | //
3421 // | | | | +---------------+ | //
3422 // | | | | | | | //
3423 // | | +---------+ | | +---------------+ //
3424 // | | | | | | | | //
3425 // +--------------+ | | v1 +------------------------------+ | | v1 //
3426 // | | | | | | | | | | | | //
3427 // RangeCheck first_store RangeCheck | | first_store //
3428 // | | | | | | | //
3429 // last_ctrl | +----> unc_trap last_ctrl | | +----> unc_trap //
3430 // | | ===> | | | //
3431 // +--------------+ | a2 v2 | | | //
3432 // | | | | | | | | //
3433 // | second_store | | | //
3434 // | | | | | [v1 v2 ... vn] //
3435 // ... ... | | | | //
3436 // | | | | | v //
3437 // +--------------+ | an vn +--------------+ | | merged_input_value //
3438 // | | | | | | | | //
3439 // last_store (= _store) merged_store //
3440 // //
3441 StoreNode* MergePrimitiveStores::make_merged_store(const Node_List& merge_list, Node* merged_input_value) {
3442 Node* first_store = merge_list.at(merge_list.size()-1);
3443 Node* last_ctrl = _store->in(MemNode::Control); // after (optional) RangeCheck
3444 Node* first_mem = first_store->in(MemNode::Memory);
3445 Node* first_adr = first_store->in(MemNode::Address);
3446
3447 const TypePtr* new_adr_type = _store->adr_type();
3448
3449 int new_memory_size = _store->memory_size() * merge_list.size();
3450 BasicType bt = T_ILLEGAL;
3451 switch (new_memory_size) {
3452 case 2: bt = T_SHORT; break;
3453 case 4: bt = T_INT; break;
3454 case 8: bt = T_LONG; break;
3455 }
3456
3457 StoreNode* merged_store = StoreNode::make(*_phase, last_ctrl, first_mem, first_adr,
3458 new_adr_type, merged_input_value, bt, MemNode::unordered);
3459
3460 // Marking the store mismatched is sufficient to prevent reordering, since array stores
3461 // are all on the same slice. Hence, we need no barriers.
3462 merged_store->set_mismatched_access();
3463
3464 // Constants above may now also be be packed -> put candidate on worklist
3465 _phase->is_IterGVN()->_worklist.push(first_mem);
3466
3467 return merged_store;
3468 }
3469
3470 #ifndef PRODUCT
3471 void MergePrimitiveStores::trace(const Node_List& merge_list, const Node* merged_input_value, const StoreNode* merged_store) const {
3472 stringStream ss;
3473 ss.print_cr("[TraceMergeStores]: Replace");
3474 for (int i = (int)merge_list.size() - 1; i >= 0; i--) {
3475 merge_list.at(i)->dump("\n", false, &ss);
3476 }
3477 ss.print_cr("[TraceMergeStores]: with");
3478 merged_input_value->dump("\n", false, &ss);
3479 merged_store->dump("\n", false, &ss);
3480 tty->print("%s", ss.as_string());
3481 }
3482 #endif
3483
3484 //------------------------------Ideal------------------------------------------
3485 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
3486 // When a store immediately follows a relevant allocation/initialization,
3487 // try to capture it into the initialization, or hoist it above.
3488 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3489 Node* p = MemNode::Ideal_common(phase, can_reshape);
3490 if (p) return (p == NodeSentinel) ? nullptr : p;
3491
3492 Node* mem = in(MemNode::Memory);
3493 Node* address = in(MemNode::Address);
3494 Node* value = in(MemNode::ValueIn);
3495 // Back-to-back stores to same address? Fold em up. Generally
3496 // unsafe if I have intervening uses.
3497 {
3498 Node* st = mem;
3499 // If Store 'st' has more than one use, we cannot fold 'st' away.
3500 // For example, 'st' might be the final state at a conditional
3501 // return. Or, 'st' might be used by some node which is live at
3502 // the same time 'st' is live, which might be unschedulable. So,
3503 // require exactly ONE user until such time as we clone 'mem' for
3504 // each of 'mem's uses (thus making the exactly-1-user-rule hold
3505 // true).
3506 while (st->is_Store() && st->outcnt() == 1) {
3507 // Looking at a dead closed cycle of memory?
3508 assert(st != st->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
3509 assert(Opcode() == st->Opcode() ||
3510 st->Opcode() == Op_StoreVector ||
3511 Opcode() == Op_StoreVector ||
3512 st->Opcode() == Op_StoreVectorScatter ||
3513 Opcode() == Op_StoreVectorScatter ||
3514 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw ||
3515 (Opcode() == Op_StoreL && st->Opcode() == Op_StoreI) || // expanded ClearArrayNode
3516 (Opcode() == Op_StoreI && st->Opcode() == Op_StoreL) || // initialization by arraycopy
3517 (is_mismatched_access() || st->as_Store()->is_mismatched_access()),
3518 "no mismatched stores, except on raw memory: %s %s", NodeClassNames[Opcode()], NodeClassNames[st->Opcode()]);
3519
3520 if (st->in(MemNode::Address)->eqv_uncast(address) &&
3521 st->as_Store()->memory_size() <= this->memory_size()) {
3522 Node* use = st->raw_out(0);
3523 if (phase->is_IterGVN()) {
3524 phase->is_IterGVN()->rehash_node_delayed(use);
3525 }
3526 // It's OK to do this in the parser, since DU info is always accurate,
3527 // and the parser always refers to nodes via SafePointNode maps.
3528 use->set_req_X(MemNode::Memory, st->in(MemNode::Memory), phase);
3529 return this;
3530 }
3531 st = st->in(MemNode::Memory);
3532 }
3533 }
3534
3535
3536 // Capture an unaliased, unconditional, simple store into an initializer.
3537 // Or, if it is independent of the allocation, hoist it above the allocation.
3538 if (ReduceFieldZeroing && /*can_reshape &&*/
3539 mem->is_Proj() && mem->in(0)->is_Initialize()) {
3540 InitializeNode* init = mem->in(0)->as_Initialize();
3541 intptr_t offset = init->can_capture_store(this, phase, can_reshape);
3542 if (offset > 0) {
3543 Node* moved = init->capture_store(this, offset, phase, can_reshape);
3544 // If the InitializeNode captured me, it made a raw copy of me,
3545 // and I need to disappear.
3546 if (moved != nullptr) {
3547 // %%% hack to ensure that Ideal returns a new node:
3548 mem = MergeMemNode::make(mem);
3549 return mem; // fold me away
3550 }
3551 }
3552 }
3553
3554 // Fold reinterpret cast into memory operation:
3555 // StoreX mem (MoveY2X v) => StoreY mem v
3556 if (value->is_Move()) {
3557 const Type* vt = value->in(1)->bottom_type();
3558 if (has_reinterpret_variant(vt)) {
3559 if (phase->C->post_loop_opts_phase()) {
3560 return convert_to_reinterpret_store(*phase, value->in(1), vt);
3561 } else {
3562 phase->C->record_for_post_loop_opts_igvn(this); // attempt the transformation once loop opts are over
3563 }
3564 }
3565 }
3566
3567 if (MergeStores && UseUnalignedAccesses) {
3568 if (phase->C->merge_stores_phase()) {
3569 MergePrimitiveStores merge(phase, this);
3570 Node* progress = merge.run();
3571 if (progress != nullptr) { return progress; }
3572 } else {
3573 // We need to wait with merging stores until RangeCheck smearing has removed the RangeChecks during
3574 // the post loops IGVN phase. If we do it earlier, then there may still be some RangeChecks between
3575 // the stores, and we merge the wrong sequence of stores.
3576 // Example:
3577 // StoreI RangeCheck StoreI StoreI RangeCheck StoreI
3578 // Apply MergeStores:
3579 // StoreI RangeCheck [ StoreL ] RangeCheck StoreI
3580 // Remove more RangeChecks:
3581 // StoreI [ StoreL ] StoreI
3582 // But now it would have been better to do this instead:
3583 // [ StoreL ] [ StoreL ]
3584 phase->C->record_for_merge_stores_igvn(this);
3585 }
3586 }
3587
3588 return nullptr; // No further progress
3589 }
3590
3591 //------------------------------Value-----------------------------------------
3592 const Type* StoreNode::Value(PhaseGVN* phase) const {
3593 // Either input is TOP ==> the result is TOP
3594 const Type *t1 = phase->type( in(MemNode::Memory) );
3595 if( t1 == Type::TOP ) return Type::TOP;
3596 const Type *t2 = phase->type( in(MemNode::Address) );
3597 if( t2 == Type::TOP ) return Type::TOP;
3598 const Type *t3 = phase->type( in(MemNode::ValueIn) );
3599 if( t3 == Type::TOP ) return Type::TOP;
3600 return Type::MEMORY;
3601 }
3602
3603 //------------------------------Identity---------------------------------------
3604 // Remove redundant stores:
3605 // Store(m, p, Load(m, p)) changes to m.
3606 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
3607 Node* StoreNode::Identity(PhaseGVN* phase) {
3608 Node* mem = in(MemNode::Memory);
3609 Node* adr = in(MemNode::Address);
3610 Node* val = in(MemNode::ValueIn);
3611
3612 Node* result = this;
3613
3614 // Load then Store? Then the Store is useless
3615 if (val->is_Load() &&
3616 val->in(MemNode::Address)->eqv_uncast(adr) &&
3617 val->in(MemNode::Memory )->eqv_uncast(mem) &&
3618 val->as_Load()->store_Opcode() == Opcode()) {
3619 if (!is_StoreVector()) {
3620 result = mem;
3621 } else if (Opcode() == Op_StoreVector && val->Opcode() == Op_LoadVector &&
3622 as_StoreVector()->vect_type() == val->as_LoadVector()->vect_type()) {
3623 // Ensure both are not masked accesses or gathers/scatters and vector types are the same
3624 result = mem;
3625 }
3626 }
3627
3628 // Two stores in a row of the same value?
3629 if (result == this &&
3630 mem->is_Store() &&
3631 mem->in(MemNode::Address)->eqv_uncast(adr) &&
3632 mem->in(MemNode::ValueIn)->eqv_uncast(val) &&
3633 mem->Opcode() == Opcode()) {
3634 if (!is_StoreVector()) {
3635 result = mem;
3636 } else {
3637 const StoreVectorNode* store_vector = as_StoreVector();
3638 const StoreVectorNode* mem_vector = mem->as_StoreVector();
3639 const Node* store_indices = store_vector->indices();
3640 const Node* mem_indices = mem_vector->indices();
3641 const Node* store_mask = store_vector->mask();
3642 const Node* mem_mask = mem_vector->mask();
3643 // Ensure types, indices, and masks match
3644 if (store_vector->vect_type() == mem_vector->vect_type() &&
3645 ((store_indices == nullptr) == (mem_indices == nullptr) &&
3646 (store_indices == nullptr || store_indices->eqv_uncast(mem_indices))) &&
3647 ((store_mask == nullptr) == (mem_mask == nullptr) &&
3648 (store_mask == nullptr || store_mask->eqv_uncast(mem_mask)))) {
3649 result = mem;
3650 }
3651 }
3652 }
3653
3654 // Store of zero anywhere into a freshly-allocated object?
3655 // Then the store is useless.
3656 // (It must already have been captured by the InitializeNode.)
3657 if (result == this &&
3658 ReduceFieldZeroing && phase->type(val)->is_zero_type()) {
3659 // a newly allocated object is already all-zeroes everywhere
3660 if (mem->is_Proj() && mem->in(0)->is_Allocate()) {
3661 result = mem;
3662 }
3663
3664 if (result == this) {
3665 // the store may also apply to zero-bits in an earlier object
3666 Node* prev_mem = find_previous_store(phase);
3667 // Steps (a), (b): Walk past independent stores to find an exact match.
3668 if (prev_mem != nullptr) {
3669 if (prev_mem->is_top()) {
3670 // find_previous_store returns top when the access is dead
3671 return prev_mem;
3672 }
3673 Node* prev_val = can_see_stored_value(prev_mem, phase);
3674 if (prev_val != nullptr && prev_val == val) {
3675 // prev_val and val might differ by a cast; it would be good
3676 // to keep the more informative of the two.
3677 result = mem;
3678 }
3679 }
3680 }
3681 }
3682
3683 PhaseIterGVN* igvn = phase->is_IterGVN();
3684 if (result != this && igvn != nullptr) {
3685 MemBarNode* trailing = trailing_membar();
3686 if (trailing != nullptr) {
3687 #ifdef ASSERT
3688 const TypeOopPtr* t_oop = phase->type(in(Address))->isa_oopptr();
3689 assert(t_oop == nullptr || t_oop->is_known_instance_field(), "only for non escaping objects");
3690 #endif
3691 trailing->remove(igvn);
3692 }
3693 }
3694
3695 return result;
3696 }
3697
3698 //------------------------------match_edge-------------------------------------
3699 // Do we Match on this edge index or not? Match only memory & value
3700 uint StoreNode::match_edge(uint idx) const {
3701 return idx == MemNode::Address || idx == MemNode::ValueIn;
3702 }
3703
3704 //------------------------------cmp--------------------------------------------
3705 // Do not common stores up together. They generally have to be split
3706 // back up anyways, so do not bother.
3707 bool StoreNode::cmp( const Node &n ) const {
3708 return (&n == this); // Always fail except on self
3709 }
3710
3711 //------------------------------Ideal_masked_input-----------------------------
3712 // Check for a useless mask before a partial-word store
3713 // (StoreB ... (AndI valIn conIa) )
3714 // If (conIa & mask == mask) this simplifies to
3715 // (StoreB ... (valIn) )
3716 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
3717 Node *val = in(MemNode::ValueIn);
3718 if( val->Opcode() == Op_AndI ) {
3719 const TypeInt *t = phase->type( val->in(2) )->isa_int();
3720 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
3721 set_req_X(MemNode::ValueIn, val->in(1), phase);
3722 return this;
3723 }
3724 }
3725 return nullptr;
3726 }
3727
3728
3729 //------------------------------Ideal_sign_extended_input----------------------
3730 // Check for useless sign-extension before a partial-word store
3731 // (StoreB ... (RShiftI _ (LShiftI _ v conIL) conIR))
3732 // If (conIL == conIR && conIR <= num_rejected_bits) this simplifies to
3733 // (StoreB ... (v))
3734 // If (conIL > conIR) under some conditions, it can be simplified into
3735 // (StoreB ... (LShiftI _ v (conIL - conIR)))
3736 // This case happens when the value of the store was itself a left shift, that
3737 // gets merged into the inner left shift of the sign-extension. For instance,
3738 // if we have
3739 // array_of_shorts[0] = (short)(v << 2)
3740 // We get a structure such as:
3741 // (StoreB ... (RShiftI _ (LShiftI _ (LShiftI _ v 2) 16) 16))
3742 // that is simplified into
3743 // (StoreB ... (RShiftI _ (LShiftI _ v 18) 16)).
3744 // It is thus useful to handle cases where conIL > conIR. But this simplification
3745 // does not always hold. Let's see in which cases it's valid.
3746 //
3747 // Let's assume we have the following 32 bits integer v:
3748 // +----------------------------------+
3749 // | v[0..31] |
3750 // +----------------------------------+
3751 // 31 0
3752 // that will be stuffed in 8 bits byte after a shift left and a shift right of
3753 // potentially different magnitudes.
3754 // We denote num_rejected_bits the number of bits of the discarded part. In this
3755 // case, num_rejected_bits == 24.
3756 //
3757 // Statement (proved further below in case analysis):
3758 // Given:
3759 // - 0 <= conIL < BitsPerJavaInteger (no wrap in shift, enforced by maskShiftAmount)
3760 // - 0 <= conIR < BitsPerJavaInteger (no wrap in shift, enforced by maskShiftAmount)
3761 // - conIL >= conIR
3762 // - num_rejected_bits >= conIR
3763 // Then this form:
3764 // (RShiftI _ (LShiftI _ v conIL) conIR)
3765 // can be replaced with this form:
3766 // (LShiftI _ v (conIL-conIR))
3767 //
3768 // Note: We only have to show that the non-rejected lowest bits (8 bits for byte)
3769 // have to be correct, as the higher bits are rejected / truncated by the store.
3770 //
3771 // The hypotheses
3772 // 0 <= conIL < BitsPerJavaInteger
3773 // 0 <= conIR < BitsPerJavaInteger
3774 // are ensured by maskShiftAmount (called from ::Ideal of shift nodes). Indeed,
3775 // (v << 31) << 2 must be simplified into 0, not into v << 33 (which is equivalent
3776 // to v << 1).
3777 //
3778 //
3779 // If you don't like case analysis, jump after the conclusion.
3780 // ### Case 1 : conIL == conIR
3781 // ###### Case 1.1: conIL == conIR == num_rejected_bits
3782 // If we do the shift left then right by 24 bits, we get:
3783 // after: v << 24
3784 // +---------+------------------------+
3785 // | v[0..7] | 0 |
3786 // +---------+------------------------+
3787 // 31 24 23 0
3788 // after: (v << 24) >> 24
3789 // +------------------------+---------+
3790 // | sign bit | v[0..7] |
3791 // +------------------------+---------+
3792 // 31 8 7 0
3793 // The non-rejected bits (bits kept by the store, that is the 8 lower bits of the
3794 // result) are the same before and after, so, indeed, simplifying is correct.
3795
3796 // ###### Case 1.2: conIL == conIR < num_rejected_bits
3797 // If we do the shift left then right by 22 bits, we get:
3798 // after: v << 22
3799 // +---------+------------------------+
3800 // | v[0..9] | 0 |
3801 // +---------+------------------------+
3802 // 31 22 21 0
3803 // after: (v << 22) >> 22
3804 // +------------------------+---------+
3805 // | sign bit | v[0..9] |
3806 // +------------------------+---------+
3807 // 31 10 9 0
3808 // The non-rejected bits are the 8 lower bits of v. The bits 8 and 9 of v are still
3809 // present in (v << 22) >> 22 but will be dropped by the store. The simplification is
3810 // still correct.
3811
3812 // ###### But! Case 1.3: conIL == conIR > num_rejected_bits
3813 // If we do the shift left then right by 26 bits, we get:
3814 // after: v << 26
3815 // +---------+------------------------+
3816 // | v[0..5] | 0 |
3817 // +---------+------------------------+
3818 // 31 26 25 0
3819 // after: (v << 26) >> 26
3820 // +------------------------+---------+
3821 // | sign bit | v[0..5] |
3822 // +------------------------+---------+
3823 // 31 6 5 0
3824 // The non-rejected bits are made of
3825 // - 0-5 => the bits 0 to 5 of v
3826 // - 6-7 => the sign bit of v[0..5] (that is v[5])
3827 // Simplifying this as v is not correct.
3828 // The condition conIR <= num_rejected_bits is indeed necessary in Case 1
3829 //
3830 // ### Case 2: conIL > conIR
3831 // ###### Case 2.1: num_rejected_bits == conIR
3832 // We take conIL == 26 for this example.
3833 // after: v << 26
3834 // +---------+------------------------+
3835 // | v[0..5] | 0 |
3836 // +---------+------------------------+
3837 // 31 26 25 0
3838 // after: (v << 26) >> 24
3839 // +------------------+---------+-----+
3840 // | sign bit | v[0..5] | 0 |
3841 // +------------------+---------+-----+
3842 // 31 8 7 2 1 0
3843 // The non-rejected bits are the 8 lower ones of (v << conIL - conIR).
3844 // The bits 6 and 7 of v have been thrown away after the shift left.
3845 // The simplification is still correct.
3846 //
3847 // ###### Case 2.2: num_rejected_bits > conIR.
3848 // Let's say conIL == 26 and conIR == 22.
3849 // after: v << 26
3850 // +---------+------------------------+
3851 // | v[0..5] | 0 |
3852 // +---------+------------------------+
3853 // 31 26 25 0
3854 // after: (v << 26) >> 22
3855 // +------------------+---------+-----+
3856 // | sign bit | v[0..5] | 0 |
3857 // +------------------+---------+-----+
3858 // 31 10 9 4 3 0
3859 // The bits non-rejected by the store are exactly the 8 lower ones of (v << (conIL - conIR)):
3860 // - 0-3 => 0
3861 // - 4-7 => bits 0 to 3 of v
3862 // The simplification is still correct.
3863 // The bits 4 and 5 of v are still present in (v << (conIL - conIR)) but they don't
3864 // matter as they are not in the 8 lower bits: they will be cut out by the store.
3865 //
3866 // ###### But! Case 2.3: num_rejected_bits < conIR.
3867 // Let's see that this case is not as easy to simplify.
3868 // Let's say conIL == 28 and conIR == 26.
3869 // after: v << 28
3870 // +---------+------------------------+
3871 // | v[0..3] | 0 |
3872 // +---------+------------------------+
3873 // 31 28 27 0
3874 // after: (v << 28) >> 26
3875 // +------------------+---------+-----+
3876 // | sign bit | v[0..3] | 0 |
3877 // +------------------+---------+-----+
3878 // 31 6 5 2 1 0
3879 // The non-rejected bits are made of
3880 // - 0-1 => 0
3881 // - 2-5 => the bits 0 to 3 of v
3882 // - 6-7 => the sign bit of v[0..3] (that is v[3])
3883 // Simplifying this as (v << 2) is not correct.
3884 // The condition conIR <= num_rejected_bits is indeed necessary in Case 2.
3885 //
3886 // ### Conclusion:
3887 // Our hypotheses are indeed sufficient:
3888 // - 0 <= conIL < BitsPerJavaInteger
3889 // - 0 <= conIR < BitsPerJavaInteger
3890 // - conIL >= conIR
3891 // - num_rejected_bits >= conIR
3892 //
3893 // ### A rationale without case analysis:
3894 // After the shift left, conIL upper bits of v are discarded and conIL lower bit
3895 // zeroes are added. After the shift right, conIR lower bits of the previous result
3896 // are discarded. If conIL >= conIR, we discard only the zeroes we made up during
3897 // the shift left, but if conIL < conIR, then we discard also lower bits of v. But
3898 // the point of the simplification is to get an expression of the form
3899 // (v << (conIL - conIR)). This expression discard only higher bits of v, thus the
3900 // simplification is not correct if conIL < conIR.
3901 //
3902 // Moreover, after the shift right, the higher bit of (v << conIL) is repeated on the
3903 // conIR higher bits of ((v << conIL) >> conIR), it's the sign-extension. If
3904 // conIR > num_rejected_bits, then at least one artificial copy of this sign bit will
3905 // be in the window of the store. Thus ((v << conIL) >> conIR) is not equivalent to
3906 // (v << (conIL-conIR)) if conIR > num_rejected_bits.
3907 //
3908 // We do not treat the case conIL < conIR here since the point of this function is
3909 // to skip sign-extensions (that is conIL == conIR == num_rejected_bits). The need
3910 // of treating conIL > conIR comes from the cases where the sign-extended value is
3911 // also left-shift expression. Computing the sign-extension of a right-shift expression
3912 // doesn't yield a situation such as
3913 // (StoreB ... (RShiftI _ (LShiftI _ v conIL) conIR))
3914 // where conIL < conIR.
3915 Node* StoreNode::Ideal_sign_extended_input(PhaseGVN* phase, int num_rejected_bits) {
3916 Node* shr = in(MemNode::ValueIn);
3917 if (shr->Opcode() == Op_RShiftI) {
3918 const TypeInt* conIR = phase->type(shr->in(2))->isa_int();
3919 if (conIR != nullptr && conIR->is_con() && conIR->get_con() >= 0 && conIR->get_con() < BitsPerJavaInteger && conIR->get_con() <= num_rejected_bits) {
3920 Node* shl = shr->in(1);
3921 if (shl->Opcode() == Op_LShiftI) {
3922 const TypeInt* conIL = phase->type(shl->in(2))->isa_int();
3923 if (conIL != nullptr && conIL->is_con() && conIL->get_con() >= 0 && conIL->get_con() < BitsPerJavaInteger) {
3924 if (conIL->get_con() == conIR->get_con()) {
3925 set_req_X(MemNode::ValueIn, shl->in(1), phase);
3926 return this;
3927 }
3928 if (conIL->get_con() > conIR->get_con()) {
3929 Node* new_shl = phase->transform(new LShiftINode(shl->in(1), phase->intcon(conIL->get_con() - conIR->get_con())));
3930 set_req_X(MemNode::ValueIn, new_shl, phase);
3931 return this;
3932 }
3933 }
3934 }
3935 }
3936 }
3937 return nullptr;
3938 }
3939
3940 //------------------------------value_never_loaded-----------------------------------
3941 // Determine whether there are any possible loads of the value stored.
3942 // For simplicity, we actually check if there are any loads from the
3943 // address stored to, not just for loads of the value stored by this node.
3944 //
3945 bool StoreNode::value_never_loaded(PhaseValues* phase) const {
3946 Node *adr = in(Address);
3947 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
3948 if (adr_oop == nullptr)
3949 return false;
3950 if (!adr_oop->is_known_instance_field())
3951 return false; // if not a distinct instance, there may be aliases of the address
3952 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
3953 Node *use = adr->fast_out(i);
3954 if (use->is_Load() || use->is_LoadStore()) {
3955 return false;
3956 }
3957 }
3958 return true;
3959 }
3960
3961 MemBarNode* StoreNode::trailing_membar() const {
3962 if (is_release()) {
3963 MemBarNode* trailing_mb = nullptr;
3964 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
3965 Node* u = fast_out(i);
3966 if (u->is_MemBar()) {
3967 if (u->as_MemBar()->trailing_store()) {
3968 assert(u->Opcode() == Op_MemBarVolatile, "");
3969 assert(trailing_mb == nullptr, "only one");
3970 trailing_mb = u->as_MemBar();
3971 #ifdef ASSERT
3972 Node* leading = u->as_MemBar()->leading_membar();
3973 assert(leading->Opcode() == Op_MemBarRelease, "incorrect membar");
3974 assert(leading->as_MemBar()->leading_store(), "incorrect membar pair");
3975 assert(leading->as_MemBar()->trailing_membar() == u, "incorrect membar pair");
3976 #endif
3977 } else {
3978 assert(u->as_MemBar()->standalone(), "");
3979 }
3980 }
3981 }
3982 return trailing_mb;
3983 }
3984 return nullptr;
3985 }
3986
3987
3988 //=============================================================================
3989 //------------------------------Ideal------------------------------------------
3990 // If the store is from an AND mask that leaves the low bits untouched, then
3991 // we can skip the AND operation. If the store is from a sign-extension
3992 // (a left shift, then right shift) we can skip both.
3993 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
3994 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
3995 if( progress != nullptr ) return progress;
3996
3997 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
3998 if( progress != nullptr ) return progress;
3999
4000 // Finally check the default case
4001 return StoreNode::Ideal(phase, can_reshape);
4002 }
4003
4004 //=============================================================================
4005 //------------------------------Ideal------------------------------------------
4006 // If the store is from an AND mask that leaves the low bits untouched, then
4007 // we can skip the AND operation
4008 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
4009 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
4010 if( progress != nullptr ) return progress;
4011
4012 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
4013 if( progress != nullptr ) return progress;
4014
4015 // Finally check the default case
4016 return StoreNode::Ideal(phase, can_reshape);
4017 }
4018
4019 //=============================================================================
4020 //----------------------------------SCMemProjNode------------------------------
4021 const Type* SCMemProjNode::Value(PhaseGVN* phase) const
4022 {
4023 if (in(0) == nullptr || phase->type(in(0)) == Type::TOP) {
4024 return Type::TOP;
4025 }
4026 return bottom_type();
4027 }
4028
4029 //=============================================================================
4030 //----------------------------------LoadStoreNode------------------------------
4031 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required )
4032 : Node(required),
4033 _type(rt),
4034 _barrier_data(0)
4035 {
4036 init_req(MemNode::Control, c );
4037 init_req(MemNode::Memory , mem);
4038 init_req(MemNode::Address, adr);
4039 init_req(MemNode::ValueIn, val);
4040 init_class_id(Class_LoadStore);
4041 DEBUG_ONLY(_adr_type = at; adr_type();)
4042 }
4043
4044 //------------------------------Value-----------------------------------------
4045 const Type* LoadStoreNode::Value(PhaseGVN* phase) const {
4046 // Either input is TOP ==> the result is TOP
4047 if (!in(MemNode::Control) || phase->type(in(MemNode::Control)) == Type::TOP) {
4048 return Type::TOP;
4049 }
4050 const Type* t = phase->type(in(MemNode::Memory));
4051 if (t == Type::TOP) {
4052 return Type::TOP;
4053 }
4054 t = phase->type(in(MemNode::Address));
4055 if (t == Type::TOP) {
4056 return Type::TOP;
4057 }
4058 t = phase->type(in(MemNode::ValueIn));
4059 if (t == Type::TOP) {
4060 return Type::TOP;
4061 }
4062 return bottom_type();
4063 }
4064
4065 const TypePtr* LoadStoreNode::adr_type() const {
4066 const TypePtr* cross_check = DEBUG_ONLY(_adr_type) NOT_DEBUG(nullptr);
4067 return MemNode::calculate_adr_type(in(MemNode::Address)->bottom_type(), cross_check);
4068 }
4069
4070 uint LoadStoreNode::ideal_reg() const {
4071 return _type->ideal_reg();
4072 }
4073
4074 // This method conservatively checks if the result of a LoadStoreNode is
4075 // used, that is, if it returns true, then it is definitely the case that
4076 // the result of the node is not needed.
4077 // For example, GetAndAdd can be matched into a lock_add instead of a
4078 // lock_xadd if the result of LoadStoreNode::result_not_used() is true
4079 bool LoadStoreNode::result_not_used() const {
4080 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
4081 Node *x = fast_out(i);
4082 if (x->Opcode() == Op_SCMemProj) {
4083 continue;
4084 }
4085 if (x->bottom_type() == TypeTuple::MEMBAR &&
4086 !x->is_Call() &&
4087 x->Opcode() != Op_Blackhole) {
4088 continue;
4089 }
4090 return false;
4091 }
4092 return true;
4093 }
4094
4095 MemBarNode* LoadStoreNode::trailing_membar() const {
4096 MemBarNode* trailing = nullptr;
4097 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
4098 Node* u = fast_out(i);
4099 if (u->is_MemBar()) {
4100 if (u->as_MemBar()->trailing_load_store()) {
4101 assert(u->Opcode() == Op_MemBarAcquire, "");
4102 assert(trailing == nullptr, "only one");
4103 trailing = u->as_MemBar();
4104 #ifdef ASSERT
4105 Node* leading = trailing->leading_membar();
4106 assert(support_IRIW_for_not_multiple_copy_atomic_cpu || leading->Opcode() == Op_MemBarRelease, "incorrect membar");
4107 assert(leading->as_MemBar()->leading_load_store(), "incorrect membar pair");
4108 assert(leading->as_MemBar()->trailing_membar() == trailing, "incorrect membar pair");
4109 #endif
4110 } else {
4111 assert(u->as_MemBar()->standalone(), "wrong barrier kind");
4112 }
4113 }
4114 }
4115
4116 return trailing;
4117 }
4118
4119 uint LoadStoreNode::size_of() const { return sizeof(*this); }
4120
4121 //=============================================================================
4122 //----------------------------------LoadStoreConditionalNode--------------------
4123 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, nullptr, TypeInt::BOOL, 5) {
4124 init_req(ExpectedIn, ex );
4125 }
4126
4127 const Type* LoadStoreConditionalNode::Value(PhaseGVN* phase) const {
4128 // Either input is TOP ==> the result is TOP
4129 const Type* t = phase->type(in(ExpectedIn));
4130 if (t == Type::TOP) {
4131 return Type::TOP;
4132 }
4133 return LoadStoreNode::Value(phase);
4134 }
4135
4136 //=============================================================================
4137 //-------------------------------adr_type--------------------------------------
4138 const TypePtr* ClearArrayNode::adr_type() const {
4139 Node *adr = in(3);
4140 if (adr == nullptr) return nullptr; // node is dead
4141 return MemNode::calculate_adr_type(adr->bottom_type());
4142 }
4143
4144 //------------------------------match_edge-------------------------------------
4145 // Do we Match on this edge index or not? Do not match memory
4146 uint ClearArrayNode::match_edge(uint idx) const {
4147 return idx > 1;
4148 }
4149
4150 //------------------------------Identity---------------------------------------
4151 // Clearing a zero length array does nothing
4152 Node* ClearArrayNode::Identity(PhaseGVN* phase) {
4153 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
4154 }
4155
4156 //------------------------------Idealize---------------------------------------
4157 // Clearing a short array is faster with stores
4158 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4159 // Already know this is a large node, do not try to ideal it
4160 if (_is_large) return nullptr;
4161
4162 const int unit = BytesPerLong;
4163 const TypeX* t = phase->type(in(2))->isa_intptr_t();
4164 if (!t) return nullptr;
4165 if (!t->is_con()) return nullptr;
4166 intptr_t raw_count = t->get_con();
4167 intptr_t size = raw_count;
4168 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
4169 // Clearing nothing uses the Identity call.
4170 // Negative clears are possible on dead ClearArrays
4171 // (see jck test stmt114.stmt11402.val).
4172 if (size <= 0 || size % unit != 0) return nullptr;
4173 intptr_t count = size / unit;
4174 // Length too long; communicate this to matchers and assemblers.
4175 // Assemblers are responsible to produce fast hardware clears for it.
4176 if (size > InitArrayShortSize) {
4177 return new ClearArrayNode(in(0), in(1), in(2), in(3), true);
4178 } else if (size > 2 && Matcher::match_rule_supported_vector(Op_ClearArray, 4, T_LONG)) {
4179 return nullptr;
4180 }
4181 if (!IdealizeClearArrayNode) return nullptr;
4182 Node *mem = in(1);
4183 if( phase->type(mem)==Type::TOP ) return nullptr;
4184 Node *adr = in(3);
4185 const Type* at = phase->type(adr);
4186 if( at==Type::TOP ) return nullptr;
4187 const TypePtr* atp = at->isa_ptr();
4188 // adjust atp to be the correct array element address type
4189 if (atp == nullptr) atp = TypePtr::BOTTOM;
4190 else atp = atp->add_offset(Type::OffsetBot);
4191 // Get base for derived pointer purposes
4192 if( adr->Opcode() != Op_AddP ) Unimplemented();
4193 Node *base = adr->in(1);
4194
4195 Node *zero = phase->makecon(TypeLong::ZERO);
4196 Node *off = phase->MakeConX(BytesPerLong);
4197 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
4198 count--;
4199 while( count-- ) {
4200 mem = phase->transform(mem);
4201 adr = phase->transform(new AddPNode(base,adr,off));
4202 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
4203 }
4204 return mem;
4205 }
4206
4207 //----------------------------step_through----------------------------------
4208 // Return allocation input memory edge if it is different instance
4209 // or itself if it is the one we are looking for.
4210 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseValues* phase) {
4211 Node* n = *np;
4212 assert(n->is_ClearArray(), "sanity");
4213 intptr_t offset;
4214 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
4215 // This method is called only before Allocate nodes are expanded
4216 // during macro nodes expansion. Before that ClearArray nodes are
4217 // only generated in PhaseMacroExpand::generate_arraycopy() (before
4218 // Allocate nodes are expanded) which follows allocations.
4219 assert(alloc != nullptr, "should have allocation");
4220 if (alloc->_idx == instance_id) {
4221 // Can not bypass initialization of the instance we are looking for.
4222 return false;
4223 }
4224 // Otherwise skip it.
4225 InitializeNode* init = alloc->initialization();
4226 if (init != nullptr)
4227 *np = init->in(TypeFunc::Memory);
4228 else
4229 *np = alloc->in(TypeFunc::Memory);
4230 return true;
4231 }
4232
4233 Node* ClearArrayNode::make_address(Node* dest, Node* offset, bool raw_base, PhaseGVN* phase) {
4234 Node* base = dest;
4235 if (raw_base) {
4236 // May be called as part of the initialization of a just allocated object
4237 base = phase->C->top();
4238 }
4239 return phase->transform(new AddPNode(base, dest, offset));
4240 }
4241
4242 //----------------------------clear_memory-------------------------------------
4243 // Generate code to initialize object storage to zero.
4244 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
4245 intptr_t start_offset,
4246 Node* end_offset,
4247 bool raw_base,
4248 PhaseGVN* phase) {
4249 intptr_t offset = start_offset;
4250
4251 int unit = BytesPerLong;
4252 if ((offset % unit) != 0) {
4253 Node* adr = make_address(dest, phase->MakeConX(offset), raw_base, phase);
4254 const TypePtr* atp = TypeRawPtr::BOTTOM;
4255 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
4256 mem = phase->transform(mem);
4257 offset += BytesPerInt;
4258 }
4259 assert((offset % unit) == 0, "");
4260
4261 // Initialize the remaining stuff, if any, with a ClearArray.
4262 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, raw_base, phase);
4263 }
4264
4265 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
4266 Node* start_offset,
4267 Node* end_offset,
4268 bool raw_base,
4269 PhaseGVN* phase) {
4270 if (start_offset == end_offset) {
4271 // nothing to do
4272 return mem;
4273 }
4274
4275 int unit = BytesPerLong;
4276 Node* zbase = start_offset;
4277 Node* zend = end_offset;
4278
4279 // Scale to the unit required by the CPU:
4280 if (!Matcher::init_array_count_is_in_bytes) {
4281 Node* shift = phase->intcon(exact_log2(unit));
4282 zbase = phase->transform(new URShiftXNode(zbase, shift) );
4283 zend = phase->transform(new URShiftXNode(zend, shift) );
4284 }
4285
4286 // Bulk clear double-words
4287 Node* zsize = phase->transform(new SubXNode(zend, zbase) );
4288 Node* adr = make_address(dest, start_offset, raw_base, phase);
4289 mem = new ClearArrayNode(ctl, mem, zsize, adr, false);
4290 return phase->transform(mem);
4291 }
4292
4293 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
4294 intptr_t start_offset,
4295 intptr_t end_offset,
4296 bool raw_base,
4297 PhaseGVN* phase) {
4298 if (start_offset == end_offset) {
4299 // nothing to do
4300 return mem;
4301 }
4302
4303 assert((end_offset % BytesPerInt) == 0, "odd end offset");
4304 intptr_t done_offset = end_offset;
4305 if ((done_offset % BytesPerLong) != 0) {
4306 done_offset -= BytesPerInt;
4307 }
4308 if (done_offset > start_offset) {
4309 mem = clear_memory(ctl, mem, dest,
4310 start_offset, phase->MakeConX(done_offset), raw_base, phase);
4311 }
4312 if (done_offset < end_offset) { // emit the final 32-bit store
4313 Node* adr = make_address(dest, phase->MakeConX(done_offset), raw_base, phase);
4314 const TypePtr* atp = TypeRawPtr::BOTTOM;
4315 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
4316 mem = phase->transform(mem);
4317 done_offset += BytesPerInt;
4318 }
4319 assert(done_offset == end_offset, "");
4320 return mem;
4321 }
4322
4323 //=============================================================================
4324 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
4325 : MultiNode(TypeFunc::Parms + (precedent == nullptr? 0: 1)),
4326 _adr_type(C->get_adr_type(alias_idx)), _kind(Standalone)
4327 #ifdef ASSERT
4328 , _pair_idx(0)
4329 #endif
4330 {
4331 init_class_id(Class_MemBar);
4332 Node* top = C->top();
4333 init_req(TypeFunc::I_O,top);
4334 init_req(TypeFunc::FramePtr,top);
4335 init_req(TypeFunc::ReturnAdr,top);
4336 if (precedent != nullptr)
4337 init_req(TypeFunc::Parms, precedent);
4338 }
4339
4340 //------------------------------cmp--------------------------------------------
4341 uint MemBarNode::hash() const { return NO_HASH; }
4342 bool MemBarNode::cmp( const Node &n ) const {
4343 return (&n == this); // Always fail except on self
4344 }
4345
4346 //------------------------------make-------------------------------------------
4347 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
4348 switch (opcode) {
4349 case Op_MemBarAcquire: return new MemBarAcquireNode(C, atp, pn);
4350 case Op_LoadFence: return new LoadFenceNode(C, atp, pn);
4351 case Op_MemBarRelease: return new MemBarReleaseNode(C, atp, pn);
4352 case Op_StoreFence: return new StoreFenceNode(C, atp, pn);
4353 case Op_MemBarStoreStore: return new MemBarStoreStoreNode(C, atp, pn);
4354 case Op_StoreStoreFence: return new StoreStoreFenceNode(C, atp, pn);
4355 case Op_MemBarAcquireLock: return new MemBarAcquireLockNode(C, atp, pn);
4356 case Op_MemBarReleaseLock: return new MemBarReleaseLockNode(C, atp, pn);
4357 case Op_MemBarStoreLoad: return new MemBarStoreLoadNode(C, atp, pn);
4358 case Op_MemBarVolatile: return new MemBarVolatileNode(C, atp, pn);
4359 case Op_MemBarFull: return new MemBarFullNode(C, atp, pn);
4360 case Op_MemBarCPUOrder: return new MemBarCPUOrderNode(C, atp, pn);
4361 case Op_OnSpinWait: return new OnSpinWaitNode(C, atp, pn);
4362 case Op_Initialize: return new InitializeNode(C, atp, pn);
4363 default: ShouldNotReachHere(); return nullptr;
4364 }
4365 }
4366
4367 void MemBarNode::remove(PhaseIterGVN *igvn) {
4368 assert(outcnt() > 0 && (outcnt() <= 2 || Opcode() == Op_Initialize), "Only one or two out edges allowed");
4369 if (trailing_store() || trailing_load_store()) {
4370 MemBarNode* leading = leading_membar();
4371 if (leading != nullptr) {
4372 assert(leading->trailing_membar() == this, "inconsistent leading/trailing membars");
4373 leading->remove(igvn);
4374 }
4375 }
4376 if (proj_out_or_null(TypeFunc::Control) != nullptr) {
4377 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
4378 }
4379 if (is_Initialize()) {
4380 as_Initialize()->replace_mem_projs_by(in(TypeFunc::Memory), igvn);
4381 } else {
4382 if (proj_out_or_null(TypeFunc::Memory) != nullptr) {
4383 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
4384 }
4385 }
4386 }
4387
4388 //------------------------------Ideal------------------------------------------
4389 // Return a node which is more "ideal" than the current node. Strip out
4390 // control copies
4391 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4392 if (remove_dead_region(phase, can_reshape)) return this;
4393 // Don't bother trying to transform a dead node
4394 if (in(0) && in(0)->is_top()) {
4395 return nullptr;
4396 }
4397
4398 bool progress = false;
4399 // Eliminate volatile MemBars for scalar replaced objects.
4400 if (can_reshape && req() == (Precedent+1)) {
4401 bool eliminate = false;
4402 int opc = Opcode();
4403 if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) {
4404 // Volatile field loads and stores.
4405 Node* my_mem = in(MemBarNode::Precedent);
4406 // The MembarAquire may keep an unused LoadNode alive through the Precedent edge
4407 if ((my_mem != nullptr) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) {
4408 // if the Precedent is a decodeN and its input (a Load) is used at more than one place,
4409 // replace this Precedent (decodeN) with the Load instead.
4410 if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1)) {
4411 Node* load_node = my_mem->in(1);
4412 set_req(MemBarNode::Precedent, load_node);
4413 phase->is_IterGVN()->_worklist.push(my_mem);
4414 my_mem = load_node;
4415 } else {
4416 assert(my_mem->unique_out() == this, "sanity");
4417 assert(!trailing_load_store(), "load store node can't be eliminated");
4418 del_req(Precedent);
4419 phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later
4420 my_mem = nullptr;
4421 }
4422 progress = true;
4423 }
4424 if (my_mem != nullptr && my_mem->is_Mem()) {
4425 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
4426 // Check for scalar replaced object reference.
4427 if( t_oop != nullptr && t_oop->is_known_instance_field() &&
4428 t_oop->offset() != Type::OffsetBot &&
4429 t_oop->offset() != Type::OffsetTop) {
4430 eliminate = true;
4431 }
4432 }
4433 } else if (opc == Op_MemBarRelease || (UseStoreStoreForCtor && opc == Op_MemBarStoreStore)) {
4434 // Final field stores.
4435 Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent));
4436 if ((alloc != nullptr) && alloc->is_Allocate() &&
4437 alloc->as_Allocate()->does_not_escape_thread()) {
4438 // The allocated object does not escape.
4439 eliminate = true;
4440 }
4441 }
4442 if (eliminate) {
4443 // Replace MemBar projections by its inputs.
4444 PhaseIterGVN* igvn = phase->is_IterGVN();
4445 remove(igvn);
4446 // Must return either the original node (now dead) or a new node
4447 // (Do not return a top here, since that would break the uniqueness of top.)
4448 return new ConINode(TypeInt::ZERO);
4449 }
4450 }
4451 return progress ? this : nullptr;
4452 }
4453
4454 //------------------------------Value------------------------------------------
4455 const Type* MemBarNode::Value(PhaseGVN* phase) const {
4456 if( !in(0) ) return Type::TOP;
4457 if( phase->type(in(0)) == Type::TOP )
4458 return Type::TOP;
4459 return TypeTuple::MEMBAR;
4460 }
4461
4462 //------------------------------match------------------------------------------
4463 // Construct projections for memory.
4464 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) {
4465 switch (proj->_con) {
4466 case TypeFunc::Control:
4467 case TypeFunc::Memory:
4468 return new MachProjNode(this, proj->_con, RegMask::EMPTY, MachProjNode::unmatched_proj);
4469 }
4470 ShouldNotReachHere();
4471 return nullptr;
4472 }
4473
4474 void MemBarNode::set_store_pair(MemBarNode* leading, MemBarNode* trailing) {
4475 trailing->_kind = TrailingStore;
4476 leading->_kind = LeadingStore;
4477 #ifdef ASSERT
4478 trailing->_pair_idx = leading->_idx;
4479 leading->_pair_idx = leading->_idx;
4480 #endif
4481 }
4482
4483 void MemBarNode::set_load_store_pair(MemBarNode* leading, MemBarNode* trailing) {
4484 trailing->_kind = TrailingLoadStore;
4485 leading->_kind = LeadingLoadStore;
4486 #ifdef ASSERT
4487 trailing->_pair_idx = leading->_idx;
4488 leading->_pair_idx = leading->_idx;
4489 #endif
4490 }
4491
4492 MemBarNode* MemBarNode::trailing_membar() const {
4493 ResourceMark rm;
4494 Node* trailing = (Node*)this;
4495 VectorSet seen;
4496 Node_Stack multis(0);
4497 do {
4498 Node* c = trailing;
4499 uint i = 0;
4500 do {
4501 trailing = nullptr;
4502 for (; i < c->outcnt(); i++) {
4503 Node* next = c->raw_out(i);
4504 if (next != c && next->is_CFG()) {
4505 if (c->is_MultiBranch()) {
4506 if (multis.node() == c) {
4507 multis.set_index(i+1);
4508 } else {
4509 multis.push(c, i+1);
4510 }
4511 }
4512 trailing = next;
4513 break;
4514 }
4515 }
4516 if (trailing != nullptr && !seen.test_set(trailing->_idx)) {
4517 break;
4518 }
4519 while (multis.size() > 0) {
4520 c = multis.node();
4521 i = multis.index();
4522 if (i < c->req()) {
4523 break;
4524 }
4525 multis.pop();
4526 }
4527 } while (multis.size() > 0);
4528 } while (!trailing->is_MemBar() || !trailing->as_MemBar()->trailing());
4529
4530 MemBarNode* mb = trailing->as_MemBar();
4531 assert((mb->_kind == TrailingStore && _kind == LeadingStore) ||
4532 (mb->_kind == TrailingLoadStore && _kind == LeadingLoadStore), "bad trailing membar");
4533 assert(mb->_pair_idx == _pair_idx, "bad trailing membar");
4534 return mb;
4535 }
4536
4537 MemBarNode* MemBarNode::leading_membar() const {
4538 ResourceMark rm;
4539 VectorSet seen;
4540 Node_Stack regions(0);
4541 Node* leading = in(0);
4542 while (leading != nullptr && (!leading->is_MemBar() || !leading->as_MemBar()->leading())) {
4543 while (leading == nullptr || leading->is_top() || seen.test_set(leading->_idx)) {
4544 leading = nullptr;
4545 while (regions.size() > 0 && leading == nullptr) {
4546 Node* r = regions.node();
4547 uint i = regions.index();
4548 if (i < r->req()) {
4549 leading = r->in(i);
4550 regions.set_index(i+1);
4551 } else {
4552 regions.pop();
4553 }
4554 }
4555 if (leading == nullptr) {
4556 assert(regions.size() == 0, "all paths should have been tried");
4557 return nullptr;
4558 }
4559 }
4560 if (leading->is_Region()) {
4561 regions.push(leading, 2);
4562 leading = leading->in(1);
4563 } else {
4564 leading = leading->in(0);
4565 }
4566 }
4567 #ifdef ASSERT
4568 Unique_Node_List wq;
4569 wq.push((Node*)this);
4570 uint found = 0;
4571 for (uint i = 0; i < wq.size(); i++) {
4572 Node* n = wq.at(i);
4573 if (n->is_Region()) {
4574 for (uint j = 1; j < n->req(); j++) {
4575 Node* in = n->in(j);
4576 if (in != nullptr && !in->is_top()) {
4577 wq.push(in);
4578 }
4579 }
4580 } else {
4581 if (n->is_MemBar() && n->as_MemBar()->leading()) {
4582 assert(n == leading, "consistency check failed");
4583 found++;
4584 } else {
4585 Node* in = n->in(0);
4586 if (in != nullptr && !in->is_top()) {
4587 wq.push(in);
4588 }
4589 }
4590 }
4591 }
4592 assert(found == 1 || (found == 0 && leading == nullptr), "consistency check failed");
4593 #endif
4594 if (leading == nullptr) {
4595 return nullptr;
4596 }
4597 MemBarNode* mb = leading->as_MemBar();
4598 assert((mb->_kind == LeadingStore && _kind == TrailingStore) ||
4599 (mb->_kind == LeadingLoadStore && _kind == TrailingLoadStore), "bad leading membar");
4600 assert(mb->_pair_idx == _pair_idx, "bad leading membar");
4601 return mb;
4602 }
4603
4604
4605 //===========================InitializeNode====================================
4606 // SUMMARY:
4607 // This node acts as a memory barrier on raw memory, after some raw stores.
4608 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
4609 // The Initialize can 'capture' suitably constrained stores as raw inits.
4610 // It can coalesce related raw stores into larger units (called 'tiles').
4611 // It can avoid zeroing new storage for memory units which have raw inits.
4612 // At macro-expansion, it is marked 'complete', and does not optimize further.
4613 //
4614 // EXAMPLE:
4615 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
4616 // ctl = incoming control; mem* = incoming memory
4617 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
4618 // First allocate uninitialized memory and fill in the header:
4619 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
4620 // ctl := alloc.Control; mem* := alloc.Memory*
4621 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
4622 // Then initialize to zero the non-header parts of the raw memory block:
4623 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
4624 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
4625 // After the initialize node executes, the object is ready for service:
4626 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
4627 // Suppose its body is immediately initialized as {1,2}:
4628 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
4629 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
4630 // mem.SLICE(#short[*]) := store2
4631 //
4632 // DETAILS:
4633 // An InitializeNode collects and isolates object initialization after
4634 // an AllocateNode and before the next possible safepoint. As a
4635 // memory barrier (MemBarNode), it keeps critical stores from drifting
4636 // down past any safepoint or any publication of the allocation.
4637 // Before this barrier, a newly-allocated object may have uninitialized bits.
4638 // After this barrier, it may be treated as a real oop, and GC is allowed.
4639 //
4640 // The semantics of the InitializeNode include an implicit zeroing of
4641 // the new object from object header to the end of the object.
4642 // (The object header and end are determined by the AllocateNode.)
4643 //
4644 // Certain stores may be added as direct inputs to the InitializeNode.
4645 // These stores must update raw memory, and they must be to addresses
4646 // derived from the raw address produced by AllocateNode, and with
4647 // a constant offset. They must be ordered by increasing offset.
4648 // The first one is at in(RawStores), the last at in(req()-1).
4649 // Unlike most memory operations, they are not linked in a chain,
4650 // but are displayed in parallel as users of the rawmem output of
4651 // the allocation.
4652 //
4653 // (See comments in InitializeNode::capture_store, which continue
4654 // the example given above.)
4655 //
4656 // When the associated Allocate is macro-expanded, the InitializeNode
4657 // may be rewritten to optimize collected stores. A ClearArrayNode
4658 // may also be created at that point to represent any required zeroing.
4659 // The InitializeNode is then marked 'complete', prohibiting further
4660 // capturing of nearby memory operations.
4661 //
4662 // During macro-expansion, all captured initializations which store
4663 // constant values of 32 bits or smaller are coalesced (if advantageous)
4664 // into larger 'tiles' 32 or 64 bits. This allows an object to be
4665 // initialized in fewer memory operations. Memory words which are
4666 // covered by neither tiles nor non-constant stores are pre-zeroed
4667 // by explicit stores of zero. (The code shape happens to do all
4668 // zeroing first, then all other stores, with both sequences occurring
4669 // in order of ascending offsets.)
4670 //
4671 // Alternatively, code may be inserted between an AllocateNode and its
4672 // InitializeNode, to perform arbitrary initialization of the new object.
4673 // E.g., the object copying intrinsics insert complex data transfers here.
4674 // The initialization must then be marked as 'complete' disable the
4675 // built-in zeroing semantics and the collection of initializing stores.
4676 //
4677 // While an InitializeNode is incomplete, reads from the memory state
4678 // produced by it are optimizable if they match the control edge and
4679 // new oop address associated with the allocation/initialization.
4680 // They return a stored value (if the offset matches) or else zero.
4681 // A write to the memory state, if it matches control and address,
4682 // and if it is to a constant offset, may be 'captured' by the
4683 // InitializeNode. It is cloned as a raw memory operation and rewired
4684 // inside the initialization, to the raw oop produced by the allocation.
4685 // Operations on addresses which are provably distinct (e.g., to
4686 // other AllocateNodes) are allowed to bypass the initialization.
4687 //
4688 // The effect of all this is to consolidate object initialization
4689 // (both arrays and non-arrays, both piecewise and bulk) into a
4690 // single location, where it can be optimized as a unit.
4691 //
4692 // Only stores with an offset less than TrackedInitializationLimit words
4693 // will be considered for capture by an InitializeNode. This puts a
4694 // reasonable limit on the complexity of optimized initializations.
4695
4696 //---------------------------InitializeNode------------------------------------
4697 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
4698 : MemBarNode(C, adr_type, rawoop),
4699 _is_complete(Incomplete), _does_not_escape(false)
4700 {
4701 init_class_id(Class_Initialize);
4702
4703 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
4704 assert(in(RawAddress) == rawoop, "proper init");
4705 // Note: allocation() can be null, for secondary initialization barriers
4706 }
4707
4708 // Since this node is not matched, it will be processed by the
4709 // register allocator. Declare that there are no constraints
4710 // on the allocation of the RawAddress edge.
4711 const RegMask &InitializeNode::in_RegMask(uint idx) const {
4712 // This edge should be set to top, by the set_complete. But be conservative.
4713 if (idx == InitializeNode::RawAddress)
4714 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
4715 return RegMask::EMPTY;
4716 }
4717
4718 Node* InitializeNode::memory(uint alias_idx) {
4719 Node* mem = in(Memory);
4720 if (mem->is_MergeMem()) {
4721 return mem->as_MergeMem()->memory_at(alias_idx);
4722 } else {
4723 // incoming raw memory is not split
4724 return mem;
4725 }
4726 }
4727
4728 bool InitializeNode::is_non_zero() {
4729 if (is_complete()) return false;
4730 remove_extra_zeroes();
4731 return (req() > RawStores);
4732 }
4733
4734 void InitializeNode::set_complete(PhaseGVN* phase) {
4735 assert(!is_complete(), "caller responsibility");
4736 _is_complete = Complete;
4737
4738 // After this node is complete, it contains a bunch of
4739 // raw-memory initializations. There is no need for
4740 // it to have anything to do with non-raw memory effects.
4741 // Therefore, tell all non-raw users to re-optimize themselves,
4742 // after skipping the memory effects of this initialization.
4743 PhaseIterGVN* igvn = phase->is_IterGVN();
4744 if (igvn) igvn->add_users_to_worklist(this);
4745 }
4746
4747 // convenience function
4748 // return false if the init contains any stores already
4749 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
4750 InitializeNode* init = initialization();
4751 if (init == nullptr || init->is_complete()) return false;
4752 init->remove_extra_zeroes();
4753 // for now, if this allocation has already collected any inits, bail:
4754 if (init->is_non_zero()) return false;
4755 init->set_complete(phase);
4756 return true;
4757 }
4758
4759 void InitializeNode::remove_extra_zeroes() {
4760 if (req() == RawStores) return;
4761 Node* zmem = zero_memory();
4762 uint fill = RawStores;
4763 for (uint i = fill; i < req(); i++) {
4764 Node* n = in(i);
4765 if (n->is_top() || n == zmem) continue; // skip
4766 if (fill < i) set_req(fill, n); // compact
4767 ++fill;
4768 }
4769 // delete any empty spaces created:
4770 while (fill < req()) {
4771 del_req(fill);
4772 }
4773 }
4774
4775 // Helper for remembering which stores go with which offsets.
4776 intptr_t InitializeNode::get_store_offset(Node* st, PhaseValues* phase) {
4777 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
4778 intptr_t offset = -1;
4779 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
4780 phase, offset);
4781 if (base == nullptr) return -1; // something is dead,
4782 if (offset < 0) return -1; // dead, dead
4783 return offset;
4784 }
4785
4786 // Helper for proving that an initialization expression is
4787 // "simple enough" to be folded into an object initialization.
4788 // Attempts to prove that a store's initial value 'n' can be captured
4789 // within the initialization without creating a vicious cycle, such as:
4790 // { Foo p = new Foo(); p.next = p; }
4791 // True for constants and parameters and small combinations thereof.
4792 bool InitializeNode::detect_init_independence(Node* value, PhaseGVN* phase) {
4793 ResourceMark rm;
4794 Unique_Node_List worklist;
4795 worklist.push(value);
4796
4797 uint complexity_limit = 20;
4798 for (uint j = 0; j < worklist.size(); j++) {
4799 if (j >= complexity_limit) {
4800 return false; // Bail out if processed too many nodes
4801 }
4802
4803 Node* n = worklist.at(j);
4804 if (n == nullptr) continue; // (can this really happen?)
4805 if (n->is_Proj()) n = n->in(0);
4806 if (n == this) return false; // found a cycle
4807 if (n->is_Con()) continue;
4808 if (n->is_Start()) continue; // params, etc., are OK
4809 if (n->is_Root()) continue; // even better
4810
4811 // There cannot be any dependency if 'n' is a CFG node that dominates the current allocation
4812 if (n->is_CFG() && phase->is_dominator(n, allocation())) {
4813 continue;
4814 }
4815
4816 Node* ctl = n->in(0);
4817 if (ctl != nullptr && !ctl->is_top()) {
4818 if (ctl->is_Proj()) ctl = ctl->in(0);
4819 if (ctl == this) return false;
4820
4821 // If we already know that the enclosing memory op is pinned right after
4822 // the init, then any control flow that the store has picked up
4823 // must have preceded the init, or else be equal to the init.
4824 // Even after loop optimizations (which might change control edges)
4825 // a store is never pinned *before* the availability of its inputs.
4826 if (!MemNode::all_controls_dominate(n, this)) {
4827 return false; // failed to prove a good control
4828 }
4829 }
4830
4831 // Check data edges for possible dependencies on 'this'.
4832 for (uint i = 1; i < n->req(); i++) {
4833 Node* m = n->in(i);
4834 if (m == nullptr || m == n || m->is_top()) continue;
4835
4836 // Only process data inputs once
4837 worklist.push(m);
4838 }
4839 }
4840
4841 return true;
4842 }
4843
4844 // Here are all the checks a Store must pass before it can be moved into
4845 // an initialization. Returns zero if a check fails.
4846 // On success, returns the (constant) offset to which the store applies,
4847 // within the initialized memory.
4848 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseGVN* phase, bool can_reshape) {
4849 const int FAIL = 0;
4850 if (st->req() != MemNode::ValueIn + 1)
4851 return FAIL; // an inscrutable StoreNode (card mark?)
4852 Node* ctl = st->in(MemNode::Control);
4853 if (!(ctl != nullptr && ctl->is_Proj() && ctl->in(0) == this))
4854 return FAIL; // must be unconditional after the initialization
4855 Node* mem = st->in(MemNode::Memory);
4856 if (!(mem->is_Proj() && mem->in(0) == this))
4857 return FAIL; // must not be preceded by other stores
4858 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
4859 if ((st->Opcode() == Op_StoreP || st->Opcode() == Op_StoreN) &&
4860 !bs->can_initialize_object(st)) {
4861 return FAIL;
4862 }
4863 Node* adr = st->in(MemNode::Address);
4864 intptr_t offset;
4865 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
4866 if (alloc == nullptr)
4867 return FAIL; // inscrutable address
4868 if (alloc != allocation())
4869 return FAIL; // wrong allocation! (store needs to float up)
4870 int size_in_bytes = st->memory_size();
4871 if ((size_in_bytes != 0) && (offset % size_in_bytes) != 0) {
4872 return FAIL; // mismatched access
4873 }
4874 Node* val = st->in(MemNode::ValueIn);
4875
4876 if (!detect_init_independence(val, phase))
4877 return FAIL; // stored value must be 'simple enough'
4878
4879 // The Store can be captured only if nothing after the allocation
4880 // and before the Store is using the memory location that the store
4881 // overwrites.
4882 bool failed = false;
4883 // If is_complete_with_arraycopy() is true the shape of the graph is
4884 // well defined and is safe so no need for extra checks.
4885 if (!is_complete_with_arraycopy()) {
4886 // We are going to look at each use of the memory state following
4887 // the allocation to make sure nothing reads the memory that the
4888 // Store writes.
4889 const TypePtr* t_adr = phase->type(adr)->isa_ptr();
4890 int alias_idx = phase->C->get_alias_index(t_adr);
4891 ResourceMark rm;
4892 Unique_Node_List mems;
4893 mems.push(mem);
4894 Node* unique_merge = nullptr;
4895 for (uint next = 0; next < mems.size(); ++next) {
4896 Node *m = mems.at(next);
4897 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
4898 Node *n = m->fast_out(j);
4899 if (n->outcnt() == 0) {
4900 continue;
4901 }
4902 if (n == st) {
4903 continue;
4904 } else if (n->in(0) != nullptr && n->in(0) != ctl) {
4905 // If the control of this use is different from the control
4906 // of the Store which is right after the InitializeNode then
4907 // this node cannot be between the InitializeNode and the
4908 // Store.
4909 continue;
4910 } else if (n->is_MergeMem()) {
4911 if (n->as_MergeMem()->memory_at(alias_idx) == m) {
4912 // We can hit a MergeMemNode (that will likely go away
4913 // later) that is a direct use of the memory state
4914 // following the InitializeNode on the same slice as the
4915 // store node that we'd like to capture. We need to check
4916 // the uses of the MergeMemNode.
4917 mems.push(n);
4918 }
4919 } else if (n->is_Mem()) {
4920 Node* other_adr = n->in(MemNode::Address);
4921 if (other_adr == adr) {
4922 failed = true;
4923 break;
4924 } else {
4925 const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr();
4926 if (other_t_adr != nullptr) {
4927 int other_alias_idx = phase->C->get_alias_index(other_t_adr);
4928 if (other_alias_idx == alias_idx) {
4929 // A load from the same memory slice as the store right
4930 // after the InitializeNode. We check the control of the
4931 // object/array that is loaded from. If it's the same as
4932 // the store control then we cannot capture the store.
4933 assert(!n->is_Store(), "2 stores to same slice on same control?");
4934 Node* base = other_adr;
4935 assert(base->is_AddP(), "should be addp but is %s", base->Name());
4936 base = base->in(AddPNode::Base);
4937 if (base != nullptr) {
4938 base = base->uncast();
4939 if (base->is_Proj() && base->in(0) == alloc) {
4940 failed = true;
4941 break;
4942 }
4943 }
4944 }
4945 }
4946 }
4947 } else {
4948 failed = true;
4949 break;
4950 }
4951 }
4952 }
4953 }
4954 if (failed) {
4955 if (!can_reshape) {
4956 // We decided we couldn't capture the store during parsing. We
4957 // should try again during the next IGVN once the graph is
4958 // cleaner.
4959 phase->C->record_for_igvn(st);
4960 }
4961 return FAIL;
4962 }
4963
4964 return offset; // success
4965 }
4966
4967 // Find the captured store in(i) which corresponds to the range
4968 // [start..start+size) in the initialized object.
4969 // If there is one, return its index i. If there isn't, return the
4970 // negative of the index where it should be inserted.
4971 // Return 0 if the queried range overlaps an initialization boundary
4972 // or if dead code is encountered.
4973 // If size_in_bytes is zero, do not bother with overlap checks.
4974 int InitializeNode::captured_store_insertion_point(intptr_t start,
4975 int size_in_bytes,
4976 PhaseValues* phase) {
4977 const int FAIL = 0, MAX_STORE = MAX2(BytesPerLong, (int)MaxVectorSize);
4978
4979 if (is_complete())
4980 return FAIL; // arraycopy got here first; punt
4981
4982 assert(allocation() != nullptr, "must be present");
4983
4984 // no negatives, no header fields:
4985 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
4986
4987 // after a certain size, we bail out on tracking all the stores:
4988 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
4989 if (start >= ti_limit) return FAIL;
4990
4991 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
4992 if (i >= limit) return -(int)i; // not found; here is where to put it
4993
4994 Node* st = in(i);
4995 intptr_t st_off = get_store_offset(st, phase);
4996 if (st_off < 0) {
4997 if (st != zero_memory()) {
4998 return FAIL; // bail out if there is dead garbage
4999 }
5000 } else if (st_off > start) {
5001 // ...we are done, since stores are ordered
5002 if (st_off < start + size_in_bytes) {
5003 return FAIL; // the next store overlaps
5004 }
5005 return -(int)i; // not found; here is where to put it
5006 } else if (st_off < start) {
5007 assert(st->as_Store()->memory_size() <= MAX_STORE, "");
5008 if (size_in_bytes != 0 &&
5009 start < st_off + MAX_STORE &&
5010 start < st_off + st->as_Store()->memory_size()) {
5011 return FAIL; // the previous store overlaps
5012 }
5013 } else {
5014 if (size_in_bytes != 0 &&
5015 st->as_Store()->memory_size() != size_in_bytes) {
5016 return FAIL; // mismatched store size
5017 }
5018 return i;
5019 }
5020
5021 ++i;
5022 }
5023 }
5024
5025 // Look for a captured store which initializes at the offset 'start'
5026 // with the given size. If there is no such store, and no other
5027 // initialization interferes, then return zero_memory (the memory
5028 // projection of the AllocateNode).
5029 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
5030 PhaseValues* phase) {
5031 assert(stores_are_sane(phase), "");
5032 int i = captured_store_insertion_point(start, size_in_bytes, phase);
5033 if (i == 0) {
5034 return nullptr; // something is dead
5035 } else if (i < 0) {
5036 return zero_memory(); // just primordial zero bits here
5037 } else {
5038 Node* st = in(i); // here is the store at this position
5039 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
5040 return st;
5041 }
5042 }
5043
5044 // Create, as a raw pointer, an address within my new object at 'offset'.
5045 Node* InitializeNode::make_raw_address(intptr_t offset,
5046 PhaseGVN* phase) {
5047 Node* addr = in(RawAddress);
5048 if (offset != 0) {
5049 Compile* C = phase->C;
5050 addr = phase->transform( new AddPNode(C->top(), addr,
5051 phase->MakeConX(offset)) );
5052 }
5053 return addr;
5054 }
5055
5056 // Clone the given store, converting it into a raw store
5057 // initializing a field or element of my new object.
5058 // Caller is responsible for retiring the original store,
5059 // with subsume_node or the like.
5060 //
5061 // From the example above InitializeNode::InitializeNode,
5062 // here are the old stores to be captured:
5063 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
5064 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
5065 //
5066 // Here is the changed code; note the extra edges on init:
5067 // alloc = (Allocate ...)
5068 // rawoop = alloc.RawAddress
5069 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
5070 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
5071 // init = (Initialize alloc.Control alloc.Memory rawoop
5072 // rawstore1 rawstore2)
5073 //
5074 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
5075 PhaseGVN* phase, bool can_reshape) {
5076 assert(stores_are_sane(phase), "");
5077
5078 if (start < 0) return nullptr;
5079 assert(can_capture_store(st, phase, can_reshape) == start, "sanity");
5080
5081 Compile* C = phase->C;
5082 int size_in_bytes = st->memory_size();
5083 int i = captured_store_insertion_point(start, size_in_bytes, phase);
5084 if (i == 0) return nullptr; // bail out
5085 Node* prev_mem = nullptr; // raw memory for the captured store
5086 if (i > 0) {
5087 prev_mem = in(i); // there is a pre-existing store under this one
5088 set_req(i, C->top()); // temporarily disconnect it
5089 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
5090 } else {
5091 i = -i; // no pre-existing store
5092 prev_mem = zero_memory(); // a slice of the newly allocated object
5093 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
5094 set_req(--i, C->top()); // reuse this edge; it has been folded away
5095 else
5096 ins_req(i, C->top()); // build a new edge
5097 }
5098 Node* new_st = st->clone_with_adr_type(TypeRawPtr::BOTTOM);
5099 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
5100 new_st->set_req(MemNode::Control, in(Control));
5101 new_st->set_req(MemNode::Memory, prev_mem);
5102 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
5103 bs->eliminate_gc_barrier_data(new_st);
5104 new_st = phase->transform(new_st);
5105
5106 // At this point, new_st might have swallowed a pre-existing store
5107 // at the same offset, or perhaps new_st might have disappeared,
5108 // if it redundantly stored the same value (or zero to fresh memory).
5109
5110 // In any case, wire it in:
5111 PhaseIterGVN* igvn = phase->is_IterGVN();
5112 if (igvn) {
5113 igvn->rehash_node_delayed(this);
5114 }
5115 set_req(i, new_st);
5116
5117 // The caller may now kill the old guy.
5118 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
5119 assert(check_st == new_st || check_st == nullptr, "must be findable");
5120 assert(!is_complete(), "");
5121 return new_st;
5122 }
5123
5124 static bool store_constant(jlong* tiles, int num_tiles,
5125 intptr_t st_off, int st_size,
5126 jlong con) {
5127 if ((st_off & (st_size-1)) != 0)
5128 return false; // strange store offset (assume size==2**N)
5129 address addr = (address)tiles + st_off;
5130 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
5131 switch (st_size) {
5132 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
5133 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
5134 case sizeof(jint): *(jint*) addr = (jint) con; break;
5135 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
5136 default: return false; // strange store size (detect size!=2**N here)
5137 }
5138 return true; // return success to caller
5139 }
5140
5141 // Coalesce subword constants into int constants and possibly
5142 // into long constants. The goal, if the CPU permits,
5143 // is to initialize the object with a small number of 64-bit tiles.
5144 // Also, convert floating-point constants to bit patterns.
5145 // Non-constants are not relevant to this pass.
5146 //
5147 // In terms of the running example on InitializeNode::InitializeNode
5148 // and InitializeNode::capture_store, here is the transformation
5149 // of rawstore1 and rawstore2 into rawstore12:
5150 // alloc = (Allocate ...)
5151 // rawoop = alloc.RawAddress
5152 // tile12 = 0x00010002
5153 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
5154 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
5155 //
5156 void
5157 InitializeNode::coalesce_subword_stores(intptr_t header_size,
5158 Node* size_in_bytes,
5159 PhaseGVN* phase) {
5160 Compile* C = phase->C;
5161
5162 assert(stores_are_sane(phase), "");
5163 // Note: After this pass, they are not completely sane,
5164 // since there may be some overlaps.
5165
5166 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
5167
5168 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
5169 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
5170 size_limit = MIN2(size_limit, ti_limit);
5171 size_limit = align_up(size_limit, BytesPerLong);
5172 int num_tiles = size_limit / BytesPerLong;
5173
5174 // allocate space for the tile map:
5175 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
5176 jlong tiles_buf[small_len];
5177 Node* nodes_buf[small_len];
5178 jlong inits_buf[small_len];
5179 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
5180 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
5181 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
5182 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
5183 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
5184 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
5185 // tiles: exact bitwise model of all primitive constants
5186 // nodes: last constant-storing node subsumed into the tiles model
5187 // inits: which bytes (in each tile) are touched by any initializations
5188
5189 //// Pass A: Fill in the tile model with any relevant stores.
5190
5191 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
5192 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
5193 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
5194 Node* zmem = zero_memory(); // initially zero memory state
5195 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
5196 Node* st = in(i);
5197 intptr_t st_off = get_store_offset(st, phase);
5198
5199 // Figure out the store's offset and constant value:
5200 if (st_off < header_size) continue; //skip (ignore header)
5201 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
5202 int st_size = st->as_Store()->memory_size();
5203 if (st_off + st_size > size_limit) break;
5204
5205 // Record which bytes are touched, whether by constant or not.
5206 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
5207 continue; // skip (strange store size)
5208
5209 const Type* val = phase->type(st->in(MemNode::ValueIn));
5210 if (!val->singleton()) continue; //skip (non-con store)
5211 BasicType type = val->basic_type();
5212
5213 jlong con = 0;
5214 switch (type) {
5215 case T_INT: con = val->is_int()->get_con(); break;
5216 case T_LONG: con = val->is_long()->get_con(); break;
5217 case T_FLOAT: con = jint_cast(val->getf()); break;
5218 case T_DOUBLE: con = jlong_cast(val->getd()); break;
5219 default: continue; //skip (odd store type)
5220 }
5221
5222 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
5223 st->Opcode() == Op_StoreL) {
5224 continue; // This StoreL is already optimal.
5225 }
5226
5227 // Store down the constant.
5228 store_constant(tiles, num_tiles, st_off, st_size, con);
5229
5230 intptr_t j = st_off >> LogBytesPerLong;
5231
5232 if (type == T_INT && st_size == BytesPerInt
5233 && (st_off & BytesPerInt) == BytesPerInt) {
5234 jlong lcon = tiles[j];
5235 if (!Matcher::isSimpleConstant64(lcon) &&
5236 st->Opcode() == Op_StoreI) {
5237 // This StoreI is already optimal by itself.
5238 jint* intcon = (jint*) &tiles[j];
5239 intcon[1] = 0; // undo the store_constant()
5240
5241 // If the previous store is also optimal by itself, back up and
5242 // undo the action of the previous loop iteration... if we can.
5243 // But if we can't, just let the previous half take care of itself.
5244 st = nodes[j];
5245 st_off -= BytesPerInt;
5246 con = intcon[0];
5247 if (con != 0 && st != nullptr && st->Opcode() == Op_StoreI) {
5248 assert(st_off >= header_size, "still ignoring header");
5249 assert(get_store_offset(st, phase) == st_off, "must be");
5250 assert(in(i-1) == zmem, "must be");
5251 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
5252 assert(con == tcon->is_int()->get_con(), "must be");
5253 // Undo the effects of the previous loop trip, which swallowed st:
5254 intcon[0] = 0; // undo store_constant()
5255 set_req(i-1, st); // undo set_req(i, zmem)
5256 nodes[j] = nullptr; // undo nodes[j] = st
5257 --old_subword; // undo ++old_subword
5258 }
5259 continue; // This StoreI is already optimal.
5260 }
5261 }
5262
5263 // This store is not needed.
5264 set_req(i, zmem);
5265 nodes[j] = st; // record for the moment
5266 if (st_size < BytesPerLong) // something has changed
5267 ++old_subword; // includes int/float, but who's counting...
5268 else ++old_long;
5269 }
5270
5271 if ((old_subword + old_long) == 0)
5272 return; // nothing more to do
5273
5274 //// Pass B: Convert any non-zero tiles into optimal constant stores.
5275 // Be sure to insert them before overlapping non-constant stores.
5276 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
5277 for (int j = 0; j < num_tiles; j++) {
5278 jlong con = tiles[j];
5279 jlong init = inits[j];
5280 if (con == 0) continue;
5281 jint con0, con1; // split the constant, address-wise
5282 jint init0, init1; // split the init map, address-wise
5283 { union { jlong con; jint intcon[2]; } u;
5284 u.con = con;
5285 con0 = u.intcon[0];
5286 con1 = u.intcon[1];
5287 u.con = init;
5288 init0 = u.intcon[0];
5289 init1 = u.intcon[1];
5290 }
5291
5292 Node* old = nodes[j];
5293 assert(old != nullptr, "need the prior store");
5294 intptr_t offset = (j * BytesPerLong);
5295
5296 bool split = !Matcher::isSimpleConstant64(con);
5297
5298 if (offset < header_size) {
5299 assert(offset + BytesPerInt >= header_size, "second int counts");
5300 assert(*(jint*)&tiles[j] == 0, "junk in header");
5301 split = true; // only the second word counts
5302 // Example: int a[] = { 42 ... }
5303 } else if (con0 == 0 && init0 == -1) {
5304 split = true; // first word is covered by full inits
5305 // Example: int a[] = { ... foo(), 42 ... }
5306 } else if (con1 == 0 && init1 == -1) {
5307 split = true; // second word is covered by full inits
5308 // Example: int a[] = { ... 42, foo() ... }
5309 }
5310
5311 // Here's a case where init0 is neither 0 nor -1:
5312 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
5313 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
5314 // In this case the tile is not split; it is (jlong)42.
5315 // The big tile is stored down, and then the foo() value is inserted.
5316 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
5317
5318 Node* ctl = old->in(MemNode::Control);
5319 Node* adr = make_raw_address(offset, phase);
5320 const TypePtr* atp = TypeRawPtr::BOTTOM;
5321
5322 // One or two coalesced stores to plop down.
5323 Node* st[2];
5324 intptr_t off[2];
5325 int nst = 0;
5326 if (!split) {
5327 ++new_long;
5328 off[nst] = offset;
5329 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
5330 phase->longcon(con), T_LONG, MemNode::unordered);
5331 } else {
5332 // Omit either if it is a zero.
5333 if (con0 != 0) {
5334 ++new_int;
5335 off[nst] = offset;
5336 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
5337 phase->intcon(con0), T_INT, MemNode::unordered);
5338 }
5339 if (con1 != 0) {
5340 ++new_int;
5341 offset += BytesPerInt;
5342 adr = make_raw_address(offset, phase);
5343 off[nst] = offset;
5344 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
5345 phase->intcon(con1), T_INT, MemNode::unordered);
5346 }
5347 }
5348
5349 // Insert second store first, then the first before the second.
5350 // Insert each one just before any overlapping non-constant stores.
5351 while (nst > 0) {
5352 Node* st1 = st[--nst];
5353 C->copy_node_notes_to(st1, old);
5354 st1 = phase->transform(st1);
5355 offset = off[nst];
5356 assert(offset >= header_size, "do not smash header");
5357 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
5358 guarantee(ins_idx != 0, "must re-insert constant store");
5359 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
5360 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
5361 set_req(--ins_idx, st1);
5362 else
5363 ins_req(ins_idx, st1);
5364 }
5365 }
5366
5367 if (PrintCompilation && WizardMode)
5368 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
5369 old_subword, old_long, new_int, new_long);
5370 if (C->log() != nullptr)
5371 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
5372 old_subword, old_long, new_int, new_long);
5373
5374 // Clean up any remaining occurrences of zmem:
5375 remove_extra_zeroes();
5376 }
5377
5378 // Explore forward from in(start) to find the first fully initialized
5379 // word, and return its offset. Skip groups of subword stores which
5380 // together initialize full words. If in(start) is itself part of a
5381 // fully initialized word, return the offset of in(start). If there
5382 // are no following full-word stores, or if something is fishy, return
5383 // a negative value.
5384 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
5385 int int_map = 0;
5386 intptr_t int_map_off = 0;
5387 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
5388
5389 for (uint i = start, limit = req(); i < limit; i++) {
5390 Node* st = in(i);
5391
5392 intptr_t st_off = get_store_offset(st, phase);
5393 if (st_off < 0) break; // return conservative answer
5394
5395 int st_size = st->as_Store()->memory_size();
5396 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
5397 return st_off; // we found a complete word init
5398 }
5399
5400 // update the map:
5401
5402 intptr_t this_int_off = align_down(st_off, BytesPerInt);
5403 if (this_int_off != int_map_off) {
5404 // reset the map:
5405 int_map = 0;
5406 int_map_off = this_int_off;
5407 }
5408
5409 int subword_off = st_off - this_int_off;
5410 int_map |= right_n_bits(st_size) << subword_off;
5411 if ((int_map & FULL_MAP) == FULL_MAP) {
5412 return this_int_off; // we found a complete word init
5413 }
5414
5415 // Did this store hit or cross the word boundary?
5416 intptr_t next_int_off = align_down(st_off + st_size, BytesPerInt);
5417 if (next_int_off == this_int_off + BytesPerInt) {
5418 // We passed the current int, without fully initializing it.
5419 int_map_off = next_int_off;
5420 int_map >>= BytesPerInt;
5421 } else if (next_int_off > this_int_off + BytesPerInt) {
5422 // We passed the current and next int.
5423 return this_int_off + BytesPerInt;
5424 }
5425 }
5426
5427 return -1;
5428 }
5429
5430
5431 // Called when the associated AllocateNode is expanded into CFG.
5432 // At this point, we may perform additional optimizations.
5433 // Linearize the stores by ascending offset, to make memory
5434 // activity as coherent as possible.
5435 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
5436 intptr_t header_size,
5437 Node* size_in_bytes,
5438 PhaseIterGVN* phase) {
5439 assert(!is_complete(), "not already complete");
5440 assert(stores_are_sane(phase), "");
5441 assert(allocation() != nullptr, "must be present");
5442
5443 remove_extra_zeroes();
5444
5445 if (ReduceFieldZeroing || ReduceBulkZeroing)
5446 // reduce instruction count for common initialization patterns
5447 coalesce_subword_stores(header_size, size_in_bytes, phase);
5448
5449 Node* zmem = zero_memory(); // initially zero memory state
5450 Node* inits = zmem; // accumulating a linearized chain of inits
5451 #ifdef ASSERT
5452 intptr_t first_offset = allocation()->minimum_header_size();
5453 intptr_t last_init_off = first_offset; // previous init offset
5454 intptr_t last_init_end = first_offset; // previous init offset+size
5455 intptr_t last_tile_end = first_offset; // previous tile offset+size
5456 #endif
5457 intptr_t zeroes_done = header_size;
5458
5459 bool do_zeroing = true; // we might give up if inits are very sparse
5460 int big_init_gaps = 0; // how many large gaps have we seen?
5461
5462 if (UseTLAB && ZeroTLAB) do_zeroing = false;
5463 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
5464
5465 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
5466 Node* st = in(i);
5467 intptr_t st_off = get_store_offset(st, phase);
5468 if (st_off < 0)
5469 break; // unknown junk in the inits
5470 if (st->in(MemNode::Memory) != zmem)
5471 break; // complicated store chains somehow in list
5472
5473 int st_size = st->as_Store()->memory_size();
5474 intptr_t next_init_off = st_off + st_size;
5475
5476 if (do_zeroing && zeroes_done < next_init_off) {
5477 // See if this store needs a zero before it or under it.
5478 intptr_t zeroes_needed = st_off;
5479
5480 if (st_size < BytesPerInt) {
5481 // Look for subword stores which only partially initialize words.
5482 // If we find some, we must lay down some word-level zeroes first,
5483 // underneath the subword stores.
5484 //
5485 // Examples:
5486 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
5487 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
5488 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
5489 //
5490 // Note: coalesce_subword_stores may have already done this,
5491 // if it was prompted by constant non-zero subword initializers.
5492 // But this case can still arise with non-constant stores.
5493
5494 intptr_t next_full_store = find_next_fullword_store(i, phase);
5495
5496 // In the examples above:
5497 // in(i) p q r s x y z
5498 // st_off 12 13 14 15 12 13 14
5499 // st_size 1 1 1 1 1 1 1
5500 // next_full_s. 12 16 16 16 16 16 16
5501 // z's_done 12 16 16 16 12 16 12
5502 // z's_needed 12 16 16 16 16 16 16
5503 // zsize 0 0 0 0 4 0 4
5504 if (next_full_store < 0) {
5505 // Conservative tack: Zero to end of current word.
5506 zeroes_needed = align_up(zeroes_needed, BytesPerInt);
5507 } else {
5508 // Zero to beginning of next fully initialized word.
5509 // Or, don't zero at all, if we are already in that word.
5510 assert(next_full_store >= zeroes_needed, "must go forward");
5511 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
5512 zeroes_needed = next_full_store;
5513 }
5514 }
5515
5516 if (zeroes_needed > zeroes_done) {
5517 intptr_t zsize = zeroes_needed - zeroes_done;
5518 // Do some incremental zeroing on rawmem, in parallel with inits.
5519 zeroes_done = align_down(zeroes_done, BytesPerInt);
5520 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
5521 zeroes_done, zeroes_needed,
5522 true,
5523 phase);
5524 zeroes_done = zeroes_needed;
5525 if (zsize > InitArrayShortSize && ++big_init_gaps > 2)
5526 do_zeroing = false; // leave the hole, next time
5527 }
5528 }
5529
5530 // Collect the store and move on:
5531 phase->replace_input_of(st, MemNode::Memory, inits);
5532 inits = st; // put it on the linearized chain
5533 set_req(i, zmem); // unhook from previous position
5534
5535 if (zeroes_done == st_off)
5536 zeroes_done = next_init_off;
5537
5538 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
5539
5540 #ifdef ASSERT
5541 // Various order invariants. Weaker than stores_are_sane because
5542 // a large constant tile can be filled in by smaller non-constant stores.
5543 assert(st_off >= last_init_off, "inits do not reverse");
5544 last_init_off = st_off;
5545 const Type* val = nullptr;
5546 if (st_size >= BytesPerInt &&
5547 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
5548 (int)val->basic_type() < (int)T_OBJECT) {
5549 assert(st_off >= last_tile_end, "tiles do not overlap");
5550 assert(st_off >= last_init_end, "tiles do not overwrite inits");
5551 last_tile_end = MAX2(last_tile_end, next_init_off);
5552 } else {
5553 intptr_t st_tile_end = align_up(next_init_off, BytesPerLong);
5554 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
5555 assert(st_off >= last_init_end, "inits do not overlap");
5556 last_init_end = next_init_off; // it's a non-tile
5557 }
5558 #endif //ASSERT
5559 }
5560
5561 remove_extra_zeroes(); // clear out all the zmems left over
5562 add_req(inits);
5563
5564 if (!(UseTLAB && ZeroTLAB)) {
5565 // If anything remains to be zeroed, zero it all now.
5566 zeroes_done = align_down(zeroes_done, BytesPerInt);
5567 // if it is the last unused 4 bytes of an instance, forget about it
5568 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
5569 if (zeroes_done + BytesPerLong >= size_limit) {
5570 AllocateNode* alloc = allocation();
5571 assert(alloc != nullptr, "must be present");
5572 if (alloc != nullptr && alloc->Opcode() == Op_Allocate) {
5573 Node* klass_node = alloc->in(AllocateNode::KlassNode);
5574 ciKlass* k = phase->type(klass_node)->is_instklassptr()->instance_klass();
5575 if (zeroes_done == k->layout_helper())
5576 zeroes_done = size_limit;
5577 }
5578 }
5579 if (zeroes_done < size_limit) {
5580 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
5581 zeroes_done, size_in_bytes, true, phase);
5582 }
5583 }
5584
5585 set_complete(phase);
5586 return rawmem;
5587 }
5588
5589 void InitializeNode::replace_mem_projs_by(Node* mem, Compile* C) {
5590 auto replace_proj = [&](ProjNode* proj) {
5591 C->gvn_replace_by(proj, mem);
5592 return CONTINUE;
5593 };
5594 apply_to_projs(replace_proj, TypeFunc::Memory);
5595 }
5596
5597 void InitializeNode::replace_mem_projs_by(Node* mem, PhaseIterGVN* igvn) {
5598 DUIterator_Fast imax, i = fast_outs(imax);
5599 auto replace_proj = [&](ProjNode* proj) {
5600 igvn->replace_node(proj, mem);
5601 --i; --imax;
5602 return CONTINUE;
5603 };
5604 apply_to_projs(imax, i, replace_proj, TypeFunc::Memory);
5605 }
5606
5607 bool InitializeNode::already_has_narrow_mem_proj_with_adr_type(const TypePtr* adr_type) const {
5608 auto find_proj = [&](ProjNode* proj) {
5609 if (proj->adr_type() == adr_type) {
5610 return BREAK_AND_RETURN_CURRENT_PROJ;
5611 }
5612 return CONTINUE;
5613 };
5614 DUIterator_Fast imax, i = fast_outs(imax);
5615 return apply_to_narrow_mem_projs_any_iterator(UsesIteratorFast(imax, i, this), find_proj) != nullptr;
5616 }
5617
5618 MachProjNode* InitializeNode::mem_mach_proj() const {
5619 auto find_proj = [](ProjNode* proj) {
5620 if (proj->is_MachProj()) {
5621 return BREAK_AND_RETURN_CURRENT_PROJ;
5622 }
5623 return CONTINUE;
5624 };
5625 ProjNode* proj = apply_to_projs(find_proj, TypeFunc::Memory);
5626 if (proj == nullptr) {
5627 return nullptr;
5628 }
5629 return proj->as_MachProj();
5630 }
5631
5632 #ifdef ASSERT
5633 bool InitializeNode::stores_are_sane(PhaseValues* phase) {
5634 if (is_complete())
5635 return true; // stores could be anything at this point
5636 assert(allocation() != nullptr, "must be present");
5637 intptr_t last_off = allocation()->minimum_header_size();
5638 for (uint i = InitializeNode::RawStores; i < req(); i++) {
5639 Node* st = in(i);
5640 intptr_t st_off = get_store_offset(st, phase);
5641 if (st_off < 0) continue; // ignore dead garbage
5642 if (last_off > st_off) {
5643 tty->print_cr("*** bad store offset at %d: %zd > %zd", i, last_off, st_off);
5644 this->dump(2);
5645 assert(false, "ascending store offsets");
5646 return false;
5647 }
5648 last_off = st_off + st->as_Store()->memory_size();
5649 }
5650 return true;
5651 }
5652 #endif //ASSERT
5653
5654
5655
5656
5657 //============================MergeMemNode=====================================
5658 //
5659 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
5660 // contributing store or call operations. Each contributor provides the memory
5661 // state for a particular "alias type" (see Compile::alias_type). For example,
5662 // if a MergeMem has an input X for alias category #6, then any memory reference
5663 // to alias category #6 may use X as its memory state input, as an exact equivalent
5664 // to using the MergeMem as a whole.
5665 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
5666 //
5667 // (Here, the <N> notation gives the index of the relevant adr_type.)
5668 //
5669 // In one special case (and more cases in the future), alias categories overlap.
5670 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
5671 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
5672 // it is exactly equivalent to that state W:
5673 // MergeMem(<Bot>: W) <==> W
5674 //
5675 // Usually, the merge has more than one input. In that case, where inputs
5676 // overlap (i.e., one is Bot), the narrower alias type determines the memory
5677 // state for that type, and the wider alias type (Bot) fills in everywhere else:
5678 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
5679 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
5680 //
5681 // A merge can take a "wide" memory state as one of its narrow inputs.
5682 // This simply means that the merge observes out only the relevant parts of
5683 // the wide input. That is, wide memory states arriving at narrow merge inputs
5684 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
5685 //
5686 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
5687 // and that memory slices "leak through":
5688 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
5689 //
5690 // But, in such a cascade, repeated memory slices can "block the leak":
5691 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
5692 //
5693 // In the last example, Y is not part of the combined memory state of the
5694 // outermost MergeMem. The system must, of course, prevent unschedulable
5695 // memory states from arising, so you can be sure that the state Y is somehow
5696 // a precursor to state Y'.
5697 //
5698 //
5699 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
5700 // of each MergeMemNode array are exactly the numerical alias indexes, including
5701 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
5702 // Compile::alias_type (and kin) produce and manage these indexes.
5703 //
5704 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
5705 // (Note that this provides quick access to the top node inside MergeMem methods,
5706 // without the need to reach out via TLS to Compile::current.)
5707 //
5708 // As a consequence of what was just described, a MergeMem that represents a full
5709 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
5710 // containing all alias categories.
5711 //
5712 // MergeMem nodes never (?) have control inputs, so in(0) is null.
5713 //
5714 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
5715 // a memory state for the alias type <N>, or else the top node, meaning that
5716 // there is no particular input for that alias type. Note that the length of
5717 // a MergeMem is variable, and may be extended at any time to accommodate new
5718 // memory states at larger alias indexes. When merges grow, they are of course
5719 // filled with "top" in the unused in() positions.
5720 //
5721 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
5722 // (Top was chosen because it works smoothly with passes like GCM.)
5723 //
5724 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
5725 // the type of random VM bits like TLS references.) Since it is always the
5726 // first non-Bot memory slice, some low-level loops use it to initialize an
5727 // index variable: for (i = AliasIdxRaw; i < req(); i++).
5728 //
5729 //
5730 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
5731 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
5732 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
5733 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
5734 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
5735 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
5736 //
5737 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
5738 // really that different from the other memory inputs. An abbreviation called
5739 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
5740 //
5741 //
5742 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
5743 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
5744 // that "emerges though" the base memory will be marked as excluding the alias types
5745 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
5746 //
5747 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
5748 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
5749 //
5750 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
5751 // (It is currently unimplemented.) As you can see, the resulting merge is
5752 // actually a disjoint union of memory states, rather than an overlay.
5753 //
5754
5755 //------------------------------MergeMemNode-----------------------------------
5756 Node* MergeMemNode::make_empty_memory() {
5757 Node* empty_memory = (Node*) Compile::current()->top();
5758 assert(empty_memory->is_top(), "correct sentinel identity");
5759 return empty_memory;
5760 }
5761
5762 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
5763 init_class_id(Class_MergeMem);
5764 // all inputs are nullified in Node::Node(int)
5765 // set_input(0, nullptr); // no control input
5766
5767 // Initialize the edges uniformly to top, for starters.
5768 Node* empty_mem = make_empty_memory();
5769 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
5770 init_req(i,empty_mem);
5771 }
5772 assert(empty_memory() == empty_mem, "");
5773
5774 if( new_base != nullptr && new_base->is_MergeMem() ) {
5775 MergeMemNode* mdef = new_base->as_MergeMem();
5776 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
5777 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
5778 mms.set_memory(mms.memory2());
5779 }
5780 assert(base_memory() == mdef->base_memory(), "");
5781 } else {
5782 set_base_memory(new_base);
5783 }
5784 }
5785
5786 // Make a new, untransformed MergeMem with the same base as 'mem'.
5787 // If mem is itself a MergeMem, populate the result with the same edges.
5788 MergeMemNode* MergeMemNode::make(Node* mem) {
5789 return new MergeMemNode(mem);
5790 }
5791
5792 //------------------------------cmp--------------------------------------------
5793 uint MergeMemNode::hash() const { return NO_HASH; }
5794 bool MergeMemNode::cmp( const Node &n ) const {
5795 return (&n == this); // Always fail except on self
5796 }
5797
5798 //------------------------------Identity---------------------------------------
5799 Node* MergeMemNode::Identity(PhaseGVN* phase) {
5800 // Identity if this merge point does not record any interesting memory
5801 // disambiguations.
5802 Node* base_mem = base_memory();
5803 Node* empty_mem = empty_memory();
5804 if (base_mem != empty_mem) { // Memory path is not dead?
5805 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5806 Node* mem = in(i);
5807 if (mem != empty_mem && mem != base_mem) {
5808 return this; // Many memory splits; no change
5809 }
5810 }
5811 }
5812 return base_mem; // No memory splits; ID on the one true input
5813 }
5814
5815 //------------------------------Ideal------------------------------------------
5816 // This method is invoked recursively on chains of MergeMem nodes
5817 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
5818 // Remove chain'd MergeMems
5819 //
5820 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
5821 // relative to the "in(Bot)". Since we are patching both at the same time,
5822 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
5823 // but rewrite each "in(i)" relative to the new "in(Bot)".
5824 Node *progress = nullptr;
5825
5826
5827 Node* old_base = base_memory();
5828 Node* empty_mem = empty_memory();
5829 if (old_base == empty_mem)
5830 return nullptr; // Dead memory path.
5831
5832 MergeMemNode* old_mbase;
5833 if (old_base != nullptr && old_base->is_MergeMem())
5834 old_mbase = old_base->as_MergeMem();
5835 else
5836 old_mbase = nullptr;
5837 Node* new_base = old_base;
5838
5839 // simplify stacked MergeMems in base memory
5840 if (old_mbase) new_base = old_mbase->base_memory();
5841
5842 // the base memory might contribute new slices beyond my req()
5843 if (old_mbase) grow_to_match(old_mbase);
5844
5845 // Note: We do not call verify_sparse on entry, because inputs
5846 // can normalize to the base_memory via subsume_node or similar
5847 // mechanisms. This method repairs that damage.
5848
5849 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
5850
5851 // Look at each slice.
5852 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5853 Node* old_in = in(i);
5854 // calculate the old memory value
5855 Node* old_mem = old_in;
5856 if (old_mem == empty_mem) old_mem = old_base;
5857 assert(old_mem == memory_at(i), "");
5858
5859 // maybe update (reslice) the old memory value
5860
5861 // simplify stacked MergeMems
5862 Node* new_mem = old_mem;
5863 MergeMemNode* old_mmem;
5864 if (old_mem != nullptr && old_mem->is_MergeMem())
5865 old_mmem = old_mem->as_MergeMem();
5866 else
5867 old_mmem = nullptr;
5868 if (old_mmem == this) {
5869 // This can happen if loops break up and safepoints disappear.
5870 // A merge of BotPtr (default) with a RawPtr memory derived from a
5871 // safepoint can be rewritten to a merge of the same BotPtr with
5872 // the BotPtr phi coming into the loop. If that phi disappears
5873 // also, we can end up with a self-loop of the mergemem.
5874 // In general, if loops degenerate and memory effects disappear,
5875 // a mergemem can be left looking at itself. This simply means
5876 // that the mergemem's default should be used, since there is
5877 // no longer any apparent effect on this slice.
5878 // Note: If a memory slice is a MergeMem cycle, it is unreachable
5879 // from start. Update the input to TOP.
5880 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
5881 }
5882 else if (old_mmem != nullptr) {
5883 new_mem = old_mmem->memory_at(i);
5884 }
5885 // else preceding memory was not a MergeMem
5886
5887 // maybe store down a new value
5888 Node* new_in = new_mem;
5889 if (new_in == new_base) new_in = empty_mem;
5890
5891 if (new_in != old_in) {
5892 // Warning: Do not combine this "if" with the previous "if"
5893 // A memory slice might have be be rewritten even if it is semantically
5894 // unchanged, if the base_memory value has changed.
5895 set_req_X(i, new_in, phase);
5896 progress = this; // Report progress
5897 }
5898 }
5899
5900 if (new_base != old_base) {
5901 set_req_X(Compile::AliasIdxBot, new_base, phase);
5902 // Don't use set_base_memory(new_base), because we need to update du.
5903 assert(base_memory() == new_base, "");
5904 progress = this;
5905 }
5906
5907 if( base_memory() == this ) {
5908 // a self cycle indicates this memory path is dead
5909 set_req(Compile::AliasIdxBot, empty_mem);
5910 }
5911
5912 // Resolve external cycles by calling Ideal on a MergeMem base_memory
5913 // Recursion must occur after the self cycle check above
5914 if( base_memory()->is_MergeMem() ) {
5915 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
5916 Node *m = phase->transform(new_mbase); // Rollup any cycles
5917 if( m != nullptr &&
5918 (m->is_top() ||
5919 (m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem)) ) {
5920 // propagate rollup of dead cycle to self
5921 set_req(Compile::AliasIdxBot, empty_mem);
5922 }
5923 }
5924
5925 if( base_memory() == empty_mem ) {
5926 progress = this;
5927 // Cut inputs during Parse phase only.
5928 // During Optimize phase a dead MergeMem node will be subsumed by Top.
5929 if( !can_reshape ) {
5930 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5931 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
5932 }
5933 }
5934 }
5935
5936 if( !progress && base_memory()->is_Phi() && can_reshape ) {
5937 // Check if PhiNode::Ideal's "Split phis through memory merges"
5938 // transform should be attempted. Look for this->phi->this cycle.
5939 uint merge_width = req();
5940 if (merge_width > Compile::AliasIdxRaw) {
5941 PhiNode* phi = base_memory()->as_Phi();
5942 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
5943 if (phi->in(i) == this) {
5944 phase->is_IterGVN()->_worklist.push(phi);
5945 break;
5946 }
5947 }
5948 }
5949 }
5950
5951 assert(progress || verify_sparse(), "please, no dups of base");
5952 return progress;
5953 }
5954
5955 //-------------------------set_base_memory-------------------------------------
5956 void MergeMemNode::set_base_memory(Node *new_base) {
5957 Node* empty_mem = empty_memory();
5958 set_req(Compile::AliasIdxBot, new_base);
5959 assert(memory_at(req()) == new_base, "must set default memory");
5960 // Clear out other occurrences of new_base:
5961 if (new_base != empty_mem) {
5962 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5963 if (in(i) == new_base) set_req(i, empty_mem);
5964 }
5965 }
5966 }
5967
5968 //------------------------------out_RegMask------------------------------------
5969 const RegMask &MergeMemNode::out_RegMask() const {
5970 return RegMask::EMPTY;
5971 }
5972
5973 //------------------------------dump_spec--------------------------------------
5974 #ifndef PRODUCT
5975 void MergeMemNode::dump_spec(outputStream *st) const {
5976 st->print(" {");
5977 Node* base_mem = base_memory();
5978 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
5979 Node* mem = (in(i) != nullptr) ? memory_at(i) : base_mem;
5980 if (mem == base_mem) { st->print(" -"); continue; }
5981 st->print( " N%d:", mem->_idx );
5982 Compile::current()->get_adr_type(i)->dump_on(st);
5983 }
5984 st->print(" }");
5985 }
5986 #endif // !PRODUCT
5987
5988
5989 #ifdef ASSERT
5990 static bool might_be_same(Node* a, Node* b) {
5991 if (a == b) return true;
5992 if (!(a->is_Phi() || b->is_Phi())) return false;
5993 // phis shift around during optimization
5994 return true; // pretty stupid...
5995 }
5996
5997 // verify a narrow slice (either incoming or outgoing)
5998 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
5999 if (!VerifyAliases) return; // don't bother to verify unless requested
6000 if (VMError::is_error_reported()) return; // muzzle asserts when debugging an error
6001 if (Node::in_dump()) return; // muzzle asserts when printing
6002 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
6003 assert(n != nullptr, "");
6004 // Elide intervening MergeMem's
6005 while (n->is_MergeMem()) {
6006 n = n->as_MergeMem()->memory_at(alias_idx);
6007 }
6008 Compile* C = Compile::current();
6009 const TypePtr* n_adr_type = n->adr_type();
6010 if (n == m->empty_memory()) {
6011 // Implicit copy of base_memory()
6012 } else if (n_adr_type != TypePtr::BOTTOM) {
6013 assert(n_adr_type != nullptr, "new memory must have a well-defined adr_type");
6014 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
6015 } else {
6016 // A few places like make_runtime_call "know" that VM calls are narrow,
6017 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
6018 bool expected_wide_mem = false;
6019 if (n == m->base_memory()) {
6020 expected_wide_mem = true;
6021 } else if (alias_idx == Compile::AliasIdxRaw ||
6022 n == m->memory_at(Compile::AliasIdxRaw)) {
6023 expected_wide_mem = true;
6024 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
6025 // memory can "leak through" calls on channels that
6026 // are write-once. Allow this also.
6027 expected_wide_mem = true;
6028 }
6029 assert(expected_wide_mem, "expected narrow slice replacement");
6030 }
6031 }
6032 #else // !ASSERT
6033 #define verify_memory_slice(m,i,n) (void)(0) // PRODUCT version is no-op
6034 #endif
6035
6036
6037 //-----------------------------memory_at---------------------------------------
6038 Node* MergeMemNode::memory_at(uint alias_idx) const {
6039 assert(alias_idx >= Compile::AliasIdxRaw ||
6040 (alias_idx == Compile::AliasIdxBot && !Compile::current()->do_aliasing()),
6041 "must avoid base_memory and AliasIdxTop");
6042
6043 // Otherwise, it is a narrow slice.
6044 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
6045 if (is_empty_memory(n)) {
6046 // the array is sparse; empty slots are the "top" node
6047 n = base_memory();
6048 assert(Node::in_dump()
6049 || n == nullptr || n->bottom_type() == Type::TOP
6050 || n->adr_type() == nullptr // address is TOP
6051 || n->adr_type() == TypePtr::BOTTOM
6052 || n->adr_type() == TypeRawPtr::BOTTOM
6053 || n->is_NarrowMemProj()
6054 || !Compile::current()->do_aliasing(),
6055 "must be a wide memory");
6056 // do_aliasing == false if we are organizing the memory states manually.
6057 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
6058 } else {
6059 // make sure the stored slice is sane
6060 #ifdef ASSERT
6061 if (VMError::is_error_reported() || Node::in_dump()) {
6062 } else if (might_be_same(n, base_memory())) {
6063 // Give it a pass: It is a mostly harmless repetition of the base.
6064 // This can arise normally from node subsumption during optimization.
6065 } else {
6066 verify_memory_slice(this, alias_idx, n);
6067 }
6068 #endif
6069 }
6070 return n;
6071 }
6072
6073 //---------------------------set_memory_at-------------------------------------
6074 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
6075 verify_memory_slice(this, alias_idx, n);
6076 Node* empty_mem = empty_memory();
6077 if (n == base_memory()) n = empty_mem; // collapse default
6078 uint need_req = alias_idx+1;
6079 if (req() < need_req) {
6080 if (n == empty_mem) return; // already the default, so do not grow me
6081 // grow the sparse array
6082 do {
6083 add_req(empty_mem);
6084 } while (req() < need_req);
6085 }
6086 set_req( alias_idx, n );
6087 }
6088
6089
6090
6091 //--------------------------iteration_setup------------------------------------
6092 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
6093 if (other != nullptr) {
6094 grow_to_match(other);
6095 // invariant: the finite support of mm2 is within mm->req()
6096 #ifdef ASSERT
6097 for (uint i = req(); i < other->req(); i++) {
6098 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
6099 }
6100 #endif
6101 }
6102 // Replace spurious copies of base_memory by top.
6103 Node* base_mem = base_memory();
6104 if (base_mem != nullptr && !base_mem->is_top()) {
6105 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
6106 if (in(i) == base_mem)
6107 set_req(i, empty_memory());
6108 }
6109 }
6110 }
6111
6112 //---------------------------grow_to_match-------------------------------------
6113 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
6114 Node* empty_mem = empty_memory();
6115 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
6116 // look for the finite support of the other memory
6117 for (uint i = other->req(); --i >= req(); ) {
6118 if (other->in(i) != empty_mem) {
6119 uint new_len = i+1;
6120 while (req() < new_len) add_req(empty_mem);
6121 break;
6122 }
6123 }
6124 }
6125
6126 //---------------------------verify_sparse-------------------------------------
6127 #ifndef PRODUCT
6128 bool MergeMemNode::verify_sparse() const {
6129 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
6130 Node* base_mem = base_memory();
6131 // The following can happen in degenerate cases, since empty==top.
6132 if (is_empty_memory(base_mem)) return true;
6133 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
6134 assert(in(i) != nullptr, "sane slice");
6135 if (in(i) == base_mem) return false; // should have been the sentinel value!
6136 }
6137 return true;
6138 }
6139
6140 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
6141 Node* n;
6142 n = mm->in(idx);
6143 if (mem == n) return true; // might be empty_memory()
6144 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
6145 if (mem == n) return true;
6146 return false;
6147 }
6148 #endif // !PRODUCT