1 /*
2 * Copyright (c) 1997, 2025, Oracle and/or its affiliates. All rights reserved.
3 * Copyright (c) 2024, Alibaba Group Holding Limited. All rights reserved.
4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
5 *
6 * This code is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License version 2 only, as
8 * published by the Free Software Foundation.
9 *
10 * This code is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13 * version 2 for more details (a copy is included in the LICENSE file that
14 * accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License version
17 * 2 along with this work; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19 *
20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21 * or visit www.oracle.com if you need additional information or have any
22 * questions.
23 *
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/regalloc.hpp"
39 #include "opto/compile.hpp"
40 #include "opto/connode.hpp"
41 #include "opto/convertnode.hpp"
42 #include "opto/loopnode.hpp"
43 #include "opto/machnode.hpp"
44 #include "opto/matcher.hpp"
45 #include "opto/memnode.hpp"
46 #include "opto/mempointer.hpp"
47 #include "opto/mulnode.hpp"
48 #include "opto/narrowptrnode.hpp"
49 #include "opto/phaseX.hpp"
50 #include "opto/regmask.hpp"
51 #include "opto/rootnode.hpp"
52 #include "opto/traceMergeStoresTag.hpp"
53 #include "opto/vectornode.hpp"
54 #include "utilities/align.hpp"
55 #include "utilities/copy.hpp"
56 #include "utilities/macros.hpp"
57 #include "utilities/powerOfTwo.hpp"
58 #include "utilities/vmError.hpp"
59
60 // Portions of code courtesy of Clifford Click
61
62 // Optimization - Graph Style
63
64 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st);
65
66 //=============================================================================
67 uint MemNode::size_of() const { return sizeof(*this); }
68
69 const TypePtr *MemNode::adr_type() const {
70 Node* adr = in(Address);
71 if (adr == nullptr) return nullptr; // node is dead
72 const TypePtr* cross_check = nullptr;
73 DEBUG_ONLY(cross_check = _adr_type);
74 return calculate_adr_type(adr->bottom_type(), cross_check);
75 }
76
77 bool MemNode::check_if_adr_maybe_raw(Node* adr) {
78 if (adr != nullptr) {
79 if (adr->bottom_type()->base() == Type::RawPtr || adr->bottom_type()->base() == Type::AnyPtr) {
80 return true;
81 }
82 }
83 return false;
84 }
85
86 #ifndef PRODUCT
87 void MemNode::dump_spec(outputStream *st) const {
88 if (in(Address) == nullptr) return; // node is dead
89 #ifndef ASSERT
90 // fake the missing field
91 const TypePtr* _adr_type = nullptr;
92 if (in(Address) != nullptr)
93 _adr_type = in(Address)->bottom_type()->isa_ptr();
94 #endif
95 dump_adr_type(this, _adr_type, st);
96
97 Compile* C = Compile::current();
98 if (C->alias_type(_adr_type)->is_volatile()) {
99 st->print(" Volatile!");
100 }
101 if (_unaligned_access) {
102 st->print(" unaligned");
103 }
104 if (_mismatched_access) {
105 st->print(" mismatched");
106 }
107 if (_unsafe_access) {
108 st->print(" unsafe");
109 }
110 }
111
112 void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) {
113 st->print(" @");
114 if (adr_type == nullptr) {
115 st->print("null");
116 } else {
117 adr_type->dump_on(st);
118 Compile* C = Compile::current();
119 Compile::AliasType* atp = nullptr;
120 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type);
121 if (atp == nullptr)
122 st->print(", idx=?\?;");
123 else if (atp->index() == Compile::AliasIdxBot)
124 st->print(", idx=Bot;");
125 else if (atp->index() == Compile::AliasIdxTop)
126 st->print(", idx=Top;");
127 else if (atp->index() == Compile::AliasIdxRaw)
128 st->print(", idx=Raw;");
129 else {
130 ciField* field = atp->field();
131 if (field) {
132 st->print(", name=");
133 field->print_name_on(st);
134 }
135 st->print(", idx=%d;", atp->index());
136 }
137 }
138 }
139
140 extern void print_alias_types();
141
142 #endif
143
144 Node *MemNode::optimize_simple_memory_chain(Node *mchain, const TypeOopPtr *t_oop, Node *load, PhaseGVN *phase) {
145 assert((t_oop != nullptr), "sanity");
146 bool is_instance = t_oop->is_known_instance_field();
147 bool is_boxed_value_load = t_oop->is_ptr_to_boxed_value() &&
148 (load != nullptr) && load->is_Load() &&
149 (phase->is_IterGVN() != nullptr);
150 if (!(is_instance || is_boxed_value_load))
151 return mchain; // don't try to optimize non-instance types
152 uint instance_id = t_oop->instance_id();
153 Node *start_mem = phase->C->start()->proj_out_or_null(TypeFunc::Memory);
154 Node *prev = nullptr;
155 Node *result = mchain;
156 while (prev != result) {
157 prev = result;
158 if (result == start_mem)
159 break; // hit one of our sentinels
160 // skip over a call which does not affect this memory slice
161 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {
162 Node *proj_in = result->in(0);
163 if (proj_in->is_Allocate() && proj_in->_idx == instance_id) {
164 break; // hit one of our sentinels
165 } else if (proj_in->is_Call()) {
166 // ArrayCopyNodes processed here as well
167 CallNode *call = proj_in->as_Call();
168 if (!call->may_modify(t_oop, phase)) { // returns false for instances
169 result = call->in(TypeFunc::Memory);
170 }
171 } else if (proj_in->is_Initialize()) {
172 AllocateNode* alloc = proj_in->as_Initialize()->allocation();
173 // Stop if this is the initialization for the object instance which
174 // contains this memory slice, otherwise skip over it.
175 if ((alloc == nullptr) || (alloc->_idx == instance_id)) {
176 break;
177 }
178 if (is_instance) {
179 result = proj_in->in(TypeFunc::Memory);
180 } else if (is_boxed_value_load) {
181 Node* klass = alloc->in(AllocateNode::KlassNode);
182 const TypeKlassPtr* tklass = phase->type(klass)->is_klassptr();
183 if (tklass->klass_is_exact() && !tklass->exact_klass()->equals(t_oop->is_instptr()->exact_klass())) {
184 result = proj_in->in(TypeFunc::Memory); // not related allocation
185 }
186 }
187 } else if (proj_in->is_MemBar()) {
188 ArrayCopyNode* ac = nullptr;
189 if (ArrayCopyNode::may_modify(t_oop, proj_in->as_MemBar(), phase, ac)) {
190 break;
191 }
192 result = proj_in->in(TypeFunc::Memory);
193 } else if (proj_in->is_top()) {
194 break; // dead code
195 } else {
196 assert(false, "unexpected projection");
197 }
198 } else if (result->is_ClearArray()) {
199 if (!is_instance || !ClearArrayNode::step_through(&result, instance_id, phase)) {
200 // Can not bypass initialization of the instance
201 // we are looking for.
202 break;
203 }
204 // Otherwise skip it (the call updated 'result' value).
205 } else if (result->is_MergeMem()) {
206 result = step_through_mergemem(phase, result->as_MergeMem(), t_oop, nullptr, tty);
207 }
208 }
209 return result;
210 }
211
212 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, Node *load, PhaseGVN *phase) {
213 const TypeOopPtr* t_oop = t_adr->isa_oopptr();
214 if (t_oop == nullptr)
215 return mchain; // don't try to optimize non-oop types
216 Node* result = optimize_simple_memory_chain(mchain, t_oop, load, phase);
217 bool is_instance = t_oop->is_known_instance_field();
218 PhaseIterGVN *igvn = phase->is_IterGVN();
219 if (is_instance && igvn != nullptr && result->is_Phi()) {
220 PhiNode *mphi = result->as_Phi();
221 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
222 const TypePtr *t = mphi->adr_type();
223 bool do_split = false;
224 // In the following cases, Load memory input can be further optimized based on
225 // its precise address type
226 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ) {
227 do_split = true;
228 } else if (t->isa_oopptr() && !t->is_oopptr()->is_known_instance()) {
229 const TypeOopPtr* mem_t =
230 t->is_oopptr()->cast_to_exactness(true)
231 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
232 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id());
233 if (t_oop->isa_aryptr()) {
234 mem_t = mem_t->is_aryptr()
235 ->cast_to_stable(t_oop->is_aryptr()->is_stable())
236 ->cast_to_size(t_oop->is_aryptr()->size())
237 ->with_offset(t_oop->is_aryptr()->offset())
238 ->is_aryptr();
239 }
240 do_split = mem_t == t_oop;
241 }
242 if (do_split) {
243 // clone the Phi with our address type
244 result = mphi->split_out_instance(t_adr, igvn);
245 } else {
246 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain");
247 }
248 }
249 return result;
250 }
251
252 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) {
253 uint alias_idx = phase->C->get_alias_index(tp);
254 Node *mem = mmem;
255 #ifdef ASSERT
256 {
257 // Check that current type is consistent with the alias index used during graph construction
258 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
259 bool consistent = adr_check == nullptr || adr_check->empty() ||
260 phase->C->must_alias(adr_check, alias_idx );
261 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
262 if( !consistent && adr_check != nullptr && !adr_check->empty() &&
263 tp->isa_aryptr() && tp->offset() == Type::OffsetBot &&
264 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot &&
265 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() ||
266 adr_check->offset() == oopDesc::klass_offset_in_bytes() ||
267 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) {
268 // don't assert if it is dead code.
269 consistent = true;
270 }
271 if( !consistent ) {
272 st->print("alias_idx==%d, adr_check==", alias_idx);
273 if( adr_check == nullptr ) {
274 st->print("null");
275 } else {
276 adr_check->dump();
277 }
278 st->cr();
279 print_alias_types();
280 assert(consistent, "adr_check must match alias idx");
281 }
282 }
283 #endif
284 // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally
285 // means an array I have not precisely typed yet. Do not do any
286 // alias stuff with it any time soon.
287 const TypeOopPtr *toop = tp->isa_oopptr();
288 if (tp->base() != Type::AnyPtr &&
289 !(toop &&
290 toop->isa_instptr() &&
291 toop->is_instptr()->instance_klass()->is_java_lang_Object() &&
292 toop->offset() == Type::OffsetBot)) {
293 // IGVN _delay_transform may be set to true and if that is the case and mmem
294 // is already a registered node then the validation inside transform will
295 // complain.
296 Node* m = mmem;
297 PhaseIterGVN* igvn = phase->is_IterGVN();
298 if (igvn == nullptr || !igvn->delay_transform()) {
299 // compress paths and change unreachable cycles to TOP
300 // If not, we can update the input infinitely along a MergeMem cycle
301 // Equivalent code in PhiNode::Ideal
302 m = phase->transform(mmem);
303 }
304 // If transformed to a MergeMem, get the desired slice
305 // Otherwise the returned node represents memory for every slice
306 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
307 // Update input if it is progress over what we have now
308 }
309 return mem;
310 }
311
312 //--------------------------Ideal_common---------------------------------------
313 // Look for degenerate control and memory inputs. Bypass MergeMem inputs.
314 // Unhook non-raw memories from complete (macro-expanded) initializations.
315 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
316 // If our control input is a dead region, kill all below the region
317 Node *ctl = in(MemNode::Control);
318 if (ctl && remove_dead_region(phase, can_reshape))
319 return this;
320 ctl = in(MemNode::Control);
321 // Don't bother trying to transform a dead node
322 if (ctl && ctl->is_top()) return NodeSentinel;
323
324 PhaseIterGVN *igvn = phase->is_IterGVN();
325 // Wait if control on the worklist.
326 if (ctl && can_reshape && igvn != nullptr) {
327 Node* bol = nullptr;
328 Node* cmp = nullptr;
329 if (ctl->in(0)->is_If()) {
330 assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity");
331 bol = ctl->in(0)->in(1);
332 if (bol->is_Bool())
333 cmp = ctl->in(0)->in(1)->in(1);
334 }
335 if (igvn->_worklist.member(ctl) ||
336 (bol != nullptr && igvn->_worklist.member(bol)) ||
337 (cmp != nullptr && igvn->_worklist.member(cmp)) ) {
338 // This control path may be dead.
339 // Delay this memory node transformation until the control is processed.
340 igvn->_worklist.push(this);
341 return NodeSentinel; // caller will return null
342 }
343 }
344 // Ignore if memory is dead, or self-loop
345 Node *mem = in(MemNode::Memory);
346 if (phase->type( mem ) == Type::TOP) return NodeSentinel; // caller will return null
347 assert(mem != this, "dead loop in MemNode::Ideal");
348
349 if (can_reshape && igvn != nullptr && igvn->_worklist.member(mem)) {
350 // This memory slice may be dead.
351 // Delay this mem node transformation until the memory is processed.
352 igvn->_worklist.push(this);
353 return NodeSentinel; // caller will return null
354 }
355
356 Node *address = in(MemNode::Address);
357 const Type *t_adr = phase->type(address);
358 if (t_adr == Type::TOP) return NodeSentinel; // caller will return null
359
360 if (can_reshape && is_unsafe_access() && (t_adr == TypePtr::NULL_PTR)) {
361 // Unsafe off-heap access with zero address. Remove access and other control users
362 // to not confuse optimizations and add a HaltNode to fail if this is ever executed.
363 assert(ctl != nullptr, "unsafe accesses should be control dependent");
364 for (DUIterator_Fast imax, i = ctl->fast_outs(imax); i < imax; i++) {
365 Node* u = ctl->fast_out(i);
366 if (u != ctl) {
367 igvn->rehash_node_delayed(u);
368 int nb = u->replace_edge(ctl, phase->C->top(), igvn);
369 --i, imax -= nb;
370 }
371 }
372 Node* frame = igvn->transform(new ParmNode(phase->C->start(), TypeFunc::FramePtr));
373 Node* halt = igvn->transform(new HaltNode(ctl, frame, "unsafe off-heap access with zero address"));
374 phase->C->root()->add_req(halt);
375 return this;
376 }
377
378 if (can_reshape && igvn != nullptr &&
379 (igvn->_worklist.member(address) ||
380 (igvn->_worklist.size() > 0 && t_adr != adr_type())) ) {
381 // The address's base and type may change when the address is processed.
382 // Delay this mem node transformation until the address is processed.
383 igvn->_worklist.push(this);
384 return NodeSentinel; // caller will return null
385 }
386
387 // Do NOT remove or optimize the next lines: ensure a new alias index
388 // is allocated for an oop pointer type before Escape Analysis.
389 // Note: C++ will not remove it since the call has side effect.
390 if (t_adr->isa_oopptr()) {
391 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr());
392 }
393
394 Node* base = nullptr;
395 if (address->is_AddP()) {
396 base = address->in(AddPNode::Base);
397 }
398 if (base != nullptr && phase->type(base)->higher_equal(TypePtr::NULL_PTR) &&
399 !t_adr->isa_rawptr()) {
400 // Note: raw address has TOP base and top->higher_equal(TypePtr::NULL_PTR) is true.
401 // Skip this node optimization if its address has TOP base.
402 return NodeSentinel; // caller will return null
403 }
404
405 // Avoid independent memory operations
406 Node* old_mem = mem;
407
408 // The code which unhooks non-raw memories from complete (macro-expanded)
409 // initializations was removed. After macro-expansion all stores caught
410 // by Initialize node became raw stores and there is no information
411 // which memory slices they modify. So it is unsafe to move any memory
412 // operation above these stores. Also in most cases hooked non-raw memories
413 // were already unhooked by using information from detect_ptr_independence()
414 // and find_previous_store().
415
416 if (mem->is_MergeMem()) {
417 MergeMemNode* mmem = mem->as_MergeMem();
418 const TypePtr *tp = t_adr->is_ptr();
419
420 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
421 }
422
423 if (mem != old_mem) {
424 set_req_X(MemNode::Memory, mem, phase);
425 if (phase->type(mem) == Type::TOP) return NodeSentinel;
426 return this;
427 }
428
429 // let the subclass continue analyzing...
430 return nullptr;
431 }
432
433 // Helper function for proving some simple control dominations.
434 // Attempt to prove that all control inputs of 'dom' dominate 'sub'.
435 // Already assumes that 'dom' is available at 'sub', and that 'sub'
436 // is not a constant (dominated by the method's StartNode).
437 // Used by MemNode::find_previous_store to prove that the
438 // control input of a memory operation predates (dominates)
439 // an allocation it wants to look past.
440 // Returns 'DomResult::Dominate' if all control inputs of 'dom'
441 // dominate 'sub', 'DomResult::NotDominate' if not,
442 // and 'DomResult::EncounteredDeadCode' if we can't decide due to
443 // dead code, but at the end of IGVN, we know the definite result
444 // once the dead code is cleaned up.
445 Node::DomResult MemNode::maybe_all_controls_dominate(Node* dom, Node* sub) {
446 if (dom == nullptr || dom->is_top() || sub == nullptr || sub->is_top()) {
447 return DomResult::EncounteredDeadCode; // Conservative answer for dead code
448 }
449
450 // Check 'dom'. Skip Proj and CatchProj nodes.
451 dom = dom->find_exact_control(dom);
452 if (dom == nullptr || dom->is_top()) {
453 return DomResult::EncounteredDeadCode; // Conservative answer for dead code
454 }
455
456 if (dom == sub) {
457 // For the case when, for example, 'sub' is Initialize and the original
458 // 'dom' is Proj node of the 'sub'.
459 return DomResult::NotDominate;
460 }
461
462 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub) {
463 return DomResult::Dominate;
464 }
465
466 // 'dom' dominates 'sub' if its control edge and control edges
467 // of all its inputs dominate or equal to sub's control edge.
468
469 // Currently 'sub' is either Allocate, Initialize or Start nodes.
470 // Or Region for the check in LoadNode::Ideal();
471 // 'sub' should have sub->in(0) != nullptr.
472 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() ||
473 sub->is_Region() || sub->is_Call(), "expecting only these nodes");
474
475 // Get control edge of 'sub'.
476 Node* orig_sub = sub;
477 sub = sub->find_exact_control(sub->in(0));
478 if (sub == nullptr || sub->is_top()) {
479 return DomResult::EncounteredDeadCode; // Conservative answer for dead code
480 }
481
482 assert(sub->is_CFG(), "expecting control");
483
484 if (sub == dom) {
485 return DomResult::Dominate;
486 }
487
488 if (sub->is_Start() || sub->is_Root()) {
489 return DomResult::NotDominate;
490 }
491
492 {
493 // Check all control edges of 'dom'.
494
495 ResourceMark rm;
496 Node_List nlist;
497 Unique_Node_List dom_list;
498
499 dom_list.push(dom);
500 bool only_dominating_controls = false;
501
502 for (uint next = 0; next < dom_list.size(); next++) {
503 Node* n = dom_list.at(next);
504 if (n == orig_sub) {
505 return DomResult::NotDominate; // One of dom's inputs dominated by sub.
506 }
507 if (!n->is_CFG() && n->pinned()) {
508 // Check only own control edge for pinned non-control nodes.
509 n = n->find_exact_control(n->in(0));
510 if (n == nullptr || n->is_top()) {
511 return DomResult::EncounteredDeadCode; // Conservative answer for dead code
512 }
513 assert(n->is_CFG(), "expecting control");
514 dom_list.push(n);
515 } else if (n->is_Con() || n->is_Start() || n->is_Root()) {
516 only_dominating_controls = true;
517 } else if (n->is_CFG()) {
518 DomResult dom_result = n->dominates(sub, nlist);
519 if (dom_result == DomResult::Dominate) {
520 only_dominating_controls = true;
521 } else {
522 return dom_result;
523 }
524 } else {
525 // First, own control edge.
526 Node* m = n->find_exact_control(n->in(0));
527 if (m != nullptr) {
528 if (m->is_top()) {
529 return DomResult::EncounteredDeadCode; // Conservative answer for dead code
530 }
531 dom_list.push(m);
532 }
533 // Now, the rest of edges.
534 uint cnt = n->req();
535 for (uint i = 1; i < cnt; i++) {
536 m = n->find_exact_control(n->in(i));
537 if (m == nullptr || m->is_top()) {
538 continue;
539 }
540 dom_list.push(m);
541 }
542 }
543 }
544 return only_dominating_controls ? DomResult::Dominate : DomResult::NotDominate;
545 }
546 }
547
548 //---------------------detect_ptr_independence---------------------------------
549 // Used by MemNode::find_previous_store to prove that two base
550 // pointers are never equal.
551 // The pointers are accompanied by their associated allocations,
552 // if any, which have been previously discovered by the caller.
553 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
554 Node* p2, AllocateNode* a2,
555 PhaseTransform* phase) {
556 // Attempt to prove that these two pointers cannot be aliased.
557 // They may both manifestly be allocations, and they should differ.
558 // Or, if they are not both allocations, they can be distinct constants.
559 // Otherwise, one is an allocation and the other a pre-existing value.
560 if (a1 == nullptr && a2 == nullptr) { // neither an allocation
561 return (p1 != p2) && p1->is_Con() && p2->is_Con();
562 } else if (a1 != nullptr && a2 != nullptr) { // both allocations
563 return (a1 != a2);
564 } else if (a1 != nullptr) { // one allocation a1
565 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.)
566 return all_controls_dominate(p2, a1);
567 } else { //(a2 != null) // one allocation a2
568 return all_controls_dominate(p1, a2);
569 }
570 return false;
571 }
572
573
574 // Find an arraycopy ac that produces the memory state represented by parameter mem.
575 // Return ac if
576 // (a) can_see_stored_value=true and ac must have set the value for this load or if
577 // (b) can_see_stored_value=false and ac could have set the value for this load or if
578 // (c) can_see_stored_value=false and ac cannot have set the value for this load.
579 // In case (c) change the parameter mem to the memory input of ac to skip it
580 // when searching stored value.
581 // Otherwise return null.
582 Node* LoadNode::find_previous_arraycopy(PhaseValues* phase, Node* ld_alloc, Node*& mem, bool can_see_stored_value) const {
583 ArrayCopyNode* ac = find_array_copy_clone(ld_alloc, mem);
584 if (ac != nullptr) {
585 Node* ld_addp = in(MemNode::Address);
586 Node* src = ac->in(ArrayCopyNode::Src);
587 const TypeAryPtr* ary_t = phase->type(src)->isa_aryptr();
588
589 // This is a load from a cloned array. The corresponding arraycopy ac must
590 // have set the value for the load and we can return ac but only if the load
591 // is known to be within bounds. This is checked below.
592 if (ary_t != nullptr && ld_addp->is_AddP()) {
593 Node* ld_offs = ld_addp->in(AddPNode::Offset);
594 BasicType ary_elem = ary_t->elem()->array_element_basic_type();
595 jlong header = arrayOopDesc::base_offset_in_bytes(ary_elem);
596 jlong elemsize = type2aelembytes(ary_elem);
597
598 const TypeX* ld_offs_t = phase->type(ld_offs)->isa_intptr_t();
599 const TypeInt* sizetype = ary_t->size();
600
601 if (ld_offs_t->_lo >= header && ld_offs_t->_hi < (sizetype->_lo * elemsize + header)) {
602 // The load is known to be within bounds. It receives its value from ac.
603 return ac;
604 }
605 // The load is known to be out-of-bounds.
606 }
607 // The load could be out-of-bounds. It must not be hoisted but must remain
608 // dependent on the runtime range check. This is achieved by returning null.
609 } else if (mem->is_Proj() && mem->in(0) != nullptr && mem->in(0)->is_ArrayCopy()) {
610 ArrayCopyNode* ac = mem->in(0)->as_ArrayCopy();
611
612 if (ac->is_arraycopy_validated() ||
613 ac->is_copyof_validated() ||
614 ac->is_copyofrange_validated()) {
615 Node* ld_addp = in(MemNode::Address);
616 if (ld_addp->is_AddP()) {
617 Node* ld_base = ld_addp->in(AddPNode::Address);
618 Node* ld_offs = ld_addp->in(AddPNode::Offset);
619
620 Node* dest = ac->in(ArrayCopyNode::Dest);
621
622 if (dest == ld_base) {
623 const TypeX* ld_offs_t = phase->type(ld_offs)->isa_intptr_t();
624 assert(!ld_offs_t->empty(), "dead reference should be checked already");
625 // Take into account vector or unsafe access size
626 jlong ld_size_in_bytes = (jlong)memory_size();
627 jlong offset_hi = ld_offs_t->_hi + ld_size_in_bytes - 1;
628 offset_hi = MIN2(offset_hi, (jlong)(TypeX::MAX->_hi)); // Take care for overflow in 32-bit VM
629 if (ac->modifies(ld_offs_t->_lo, (intptr_t)offset_hi, phase, can_see_stored_value)) {
630 return ac;
631 }
632 if (!can_see_stored_value) {
633 mem = ac->in(TypeFunc::Memory);
634 return ac;
635 }
636 }
637 }
638 }
639 }
640 return nullptr;
641 }
642
643 ArrayCopyNode* MemNode::find_array_copy_clone(Node* ld_alloc, Node* mem) const {
644 if (mem->is_Proj() && mem->in(0) != nullptr && (mem->in(0)->Opcode() == Op_MemBarStoreStore ||
645 mem->in(0)->Opcode() == Op_MemBarCPUOrder)) {
646 if (ld_alloc != nullptr) {
647 // Check if there is an array copy for a clone
648 Node* mb = mem->in(0);
649 ArrayCopyNode* ac = nullptr;
650 if (mb->in(0) != nullptr && mb->in(0)->is_Proj() &&
651 mb->in(0)->in(0) != nullptr && mb->in(0)->in(0)->is_ArrayCopy()) {
652 ac = mb->in(0)->in(0)->as_ArrayCopy();
653 } else {
654 // Step over GC barrier when ReduceInitialCardMarks is disabled
655 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
656 Node* control_proj_ac = bs->step_over_gc_barrier(mb->in(0));
657
658 if (control_proj_ac->is_Proj() && control_proj_ac->in(0)->is_ArrayCopy()) {
659 ac = control_proj_ac->in(0)->as_ArrayCopy();
660 }
661 }
662
663 if (ac != nullptr && ac->is_clonebasic()) {
664 AllocateNode* alloc = AllocateNode::Ideal_allocation(ac->in(ArrayCopyNode::Dest));
665 if (alloc != nullptr && alloc == ld_alloc) {
666 return ac;
667 }
668 }
669 }
670 }
671 return nullptr;
672 }
673
674 // The logic for reordering loads and stores uses four steps:
675 // (a) Walk carefully past stores and initializations which we
676 // can prove are independent of this load.
677 // (b) Observe that the next memory state makes an exact match
678 // with self (load or store), and locate the relevant store.
679 // (c) Ensure that, if we were to wire self directly to the store,
680 // the optimizer would fold it up somehow.
681 // (d) Do the rewiring, and return, depending on some other part of
682 // the optimizer to fold up the load.
683 // This routine handles steps (a) and (b). Steps (c) and (d) are
684 // specific to loads and stores, so they are handled by the callers.
685 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.)
686 //
687 Node* MemNode::find_previous_store(PhaseValues* phase) {
688 Node* ctrl = in(MemNode::Control);
689 Node* adr = in(MemNode::Address);
690 intptr_t offset = 0;
691 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
692 AllocateNode* alloc = AllocateNode::Ideal_allocation(base);
693
694 if (offset == Type::OffsetBot)
695 return nullptr; // cannot unalias unless there are precise offsets
696
697 const bool adr_maybe_raw = check_if_adr_maybe_raw(adr);
698 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr();
699
700 intptr_t size_in_bytes = memory_size();
701
702 Node* mem = in(MemNode::Memory); // start searching here...
703
704 int cnt = 50; // Cycle limiter
705 for (;;) { // While we can dance past unrelated stores...
706 if (--cnt < 0) break; // Caught in cycle or a complicated dance?
707
708 Node* prev = mem;
709 if (mem->is_Store()) {
710 Node* st_adr = mem->in(MemNode::Address);
711 intptr_t st_offset = 0;
712 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
713 if (st_base == nullptr)
714 break; // inscrutable pointer
715
716 // For raw accesses it's not enough to prove that constant offsets don't intersect.
717 // We need the bases to be the equal in order for the offset check to make sense.
718 if ((adr_maybe_raw || check_if_adr_maybe_raw(st_adr)) && st_base != base) {
719 break;
720 }
721
722 if (st_offset != offset && st_offset != Type::OffsetBot) {
723 const int MAX_STORE = MAX2(BytesPerLong, (int)MaxVectorSize);
724 assert(mem->as_Store()->memory_size() <= MAX_STORE, "");
725 if (st_offset >= offset + size_in_bytes ||
726 st_offset <= offset - MAX_STORE ||
727 st_offset <= offset - mem->as_Store()->memory_size()) {
728 // Success: The offsets are provably independent.
729 // (You may ask, why not just test st_offset != offset and be done?
730 // The answer is that stores of different sizes can co-exist
731 // in the same sequence of RawMem effects. We sometimes initialize
732 // a whole 'tile' of array elements with a single jint or jlong.)
733 mem = mem->in(MemNode::Memory);
734 continue; // (a) advance through independent store memory
735 }
736 }
737 if (st_base != base &&
738 detect_ptr_independence(base, alloc,
739 st_base,
740 AllocateNode::Ideal_allocation(st_base),
741 phase)) {
742 // Success: The bases are provably independent.
743 mem = mem->in(MemNode::Memory);
744 continue; // (a) advance through independent store memory
745 }
746
747 // (b) At this point, if the bases or offsets do not agree, we lose,
748 // since we have not managed to prove 'this' and 'mem' independent.
749 if (st_base == base && st_offset == offset) {
750 return mem; // let caller handle steps (c), (d)
751 }
752
753 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
754 InitializeNode* st_init = mem->in(0)->as_Initialize();
755 AllocateNode* st_alloc = st_init->allocation();
756 if (st_alloc == nullptr) {
757 break; // something degenerated
758 }
759 bool known_identical = false;
760 bool known_independent = false;
761 if (alloc == st_alloc) {
762 known_identical = true;
763 } else if (alloc != nullptr) {
764 known_independent = true;
765 } else if (all_controls_dominate(this, st_alloc)) {
766 known_independent = true;
767 }
768
769 if (known_independent) {
770 // The bases are provably independent: Either they are
771 // manifestly distinct allocations, or else the control
772 // of this load dominates the store's allocation.
773 int alias_idx = phase->C->get_alias_index(adr_type());
774 if (alias_idx == Compile::AliasIdxRaw) {
775 mem = st_alloc->in(TypeFunc::Memory);
776 } else {
777 mem = st_init->memory(alias_idx);
778 }
779 continue; // (a) advance through independent store memory
780 }
781
782 // (b) at this point, if we are not looking at a store initializing
783 // the same allocation we are loading from, we lose.
784 if (known_identical) {
785 // From caller, can_see_stored_value will consult find_captured_store.
786 return mem; // let caller handle steps (c), (d)
787 }
788
789 } else if (find_previous_arraycopy(phase, alloc, mem, false) != nullptr) {
790 if (prev != mem) {
791 // Found an arraycopy but it doesn't affect that load
792 continue;
793 }
794 // Found an arraycopy that may affect that load
795 return mem;
796 } else if (addr_t != nullptr && addr_t->is_known_instance_field()) {
797 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
798 if (mem->is_Proj() && mem->in(0)->is_Call()) {
799 // ArrayCopyNodes processed here as well.
800 CallNode *call = mem->in(0)->as_Call();
801 if (!call->may_modify(addr_t, phase)) {
802 mem = call->in(TypeFunc::Memory);
803 continue; // (a) advance through independent call memory
804 }
805 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) {
806 ArrayCopyNode* ac = nullptr;
807 if (ArrayCopyNode::may_modify(addr_t, mem->in(0)->as_MemBar(), phase, ac)) {
808 break;
809 }
810 mem = mem->in(0)->in(TypeFunc::Memory);
811 continue; // (a) advance through independent MemBar memory
812 } else if (mem->is_ClearArray()) {
813 if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) {
814 // (the call updated 'mem' value)
815 continue; // (a) advance through independent allocation memory
816 } else {
817 // Can not bypass initialization of the instance
818 // we are looking for.
819 return mem;
820 }
821 } else if (mem->is_MergeMem()) {
822 int alias_idx = phase->C->get_alias_index(adr_type());
823 mem = mem->as_MergeMem()->memory_at(alias_idx);
824 continue; // (a) advance through independent MergeMem memory
825 }
826 }
827
828 // Unless there is an explicit 'continue', we must bail out here,
829 // because 'mem' is an inscrutable memory state (e.g., a call).
830 break;
831 }
832
833 return nullptr; // bail out
834 }
835
836 //----------------------calculate_adr_type-------------------------------------
837 // Helper function. Notices when the given type of address hits top or bottom.
838 // Also, asserts a cross-check of the type against the expected address type.
839 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
840 if (t == Type::TOP) return nullptr; // does not touch memory any more?
841 #ifdef ASSERT
842 if (!VerifyAliases || VMError::is_error_reported() || Node::in_dump()) cross_check = nullptr;
843 #endif
844 const TypePtr* tp = t->isa_ptr();
845 if (tp == nullptr) {
846 assert(cross_check == nullptr || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
847 return TypePtr::BOTTOM; // touches lots of memory
848 } else {
849 #ifdef ASSERT
850 // %%%% [phh] We don't check the alias index if cross_check is
851 // TypeRawPtr::BOTTOM. Needs to be investigated.
852 if (cross_check != nullptr &&
853 cross_check != TypePtr::BOTTOM &&
854 cross_check != TypeRawPtr::BOTTOM) {
855 // Recheck the alias index, to see if it has changed (due to a bug).
856 Compile* C = Compile::current();
857 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
858 "must stay in the original alias category");
859 // The type of the address must be contained in the adr_type,
860 // disregarding "null"-ness.
861 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
862 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
863 assert(cross_check->meet(tp_notnull) == cross_check->remove_speculative(),
864 "real address must not escape from expected memory type");
865 }
866 #endif
867 return tp;
868 }
869 }
870
871 uint8_t MemNode::barrier_data(const Node* n) {
872 if (n->is_LoadStore()) {
873 return n->as_LoadStore()->barrier_data();
874 } else if (n->is_Mem()) {
875 return n->as_Mem()->barrier_data();
876 }
877 return 0;
878 }
879
880 //=============================================================================
881 // Should LoadNode::Ideal() attempt to remove control edges?
882 bool LoadNode::can_remove_control() const {
883 return !has_pinned_control_dependency();
884 }
885 uint LoadNode::size_of() const { return sizeof(*this); }
886 bool LoadNode::cmp(const Node &n) const {
887 LoadNode& load = (LoadNode &)n;
888 return Type::equals(_type, load._type) &&
889 _control_dependency == load._control_dependency &&
890 _mo == load._mo;
891 }
892 const Type *LoadNode::bottom_type() const { return _type; }
893 uint LoadNode::ideal_reg() const {
894 return _type->ideal_reg();
895 }
896
897 #ifndef PRODUCT
898 void LoadNode::dump_spec(outputStream *st) const {
899 MemNode::dump_spec(st);
900 if( !Verbose && !WizardMode ) {
901 // standard dump does this in Verbose and WizardMode
902 st->print(" #"); _type->dump_on(st);
903 }
904 if (!depends_only_on_test()) {
905 st->print(" (does not depend only on test, ");
906 if (control_dependency() == UnknownControl) {
907 st->print("unknown control");
908 } else if (control_dependency() == Pinned) {
909 st->print("pinned");
910 } else if (adr_type() == TypeRawPtr::BOTTOM) {
911 st->print("raw access");
912 } else {
913 st->print("unknown reason");
914 }
915 st->print(")");
916 }
917 }
918 #endif
919
920 #ifdef ASSERT
921 //----------------------------is_immutable_value-------------------------------
922 // Helper function to allow a raw load without control edge for some cases
923 bool LoadNode::is_immutable_value(Node* adr) {
924 if (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() &&
925 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal) {
926
927 jlong offset = adr->in(AddPNode::Offset)->find_intptr_t_con(-1);
928 int offsets[] = {
929 in_bytes(JavaThread::osthread_offset()),
930 in_bytes(JavaThread::threadObj_offset()),
931 in_bytes(JavaThread::vthread_offset()),
932 in_bytes(JavaThread::scopedValueCache_offset()),
933 };
934
935 for (size_t i = 0; i < sizeof offsets / sizeof offsets[0]; i++) {
936 if (offset == offsets[i]) {
937 return true;
938 }
939 }
940 }
941
942 return false;
943 }
944 #endif
945
946 //----------------------------LoadNode::make-----------------------------------
947 // Polymorphic factory method:
948 Node* LoadNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, BasicType bt, MemOrd mo,
949 ControlDependency control_dependency, bool require_atomic_access, bool unaligned, bool mismatched, bool unsafe, uint8_t barrier_data) {
950 Compile* C = gvn.C;
951
952 // sanity check the alias category against the created node type
953 assert(!(adr_type->isa_oopptr() &&
954 adr_type->offset() == oopDesc::klass_offset_in_bytes()),
955 "use LoadKlassNode instead");
956 assert(!(adr_type->isa_aryptr() &&
957 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
958 "use LoadRangeNode instead");
959 // Check control edge of raw loads
960 assert( ctl != nullptr || C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
961 // oop will be recorded in oop map if load crosses safepoint
962 rt->isa_oopptr() || is_immutable_value(adr),
963 "raw memory operations should have control edge");
964 LoadNode* load = nullptr;
965 switch (bt) {
966 case T_BOOLEAN: load = new LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
967 case T_BYTE: load = new LoadBNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
968 case T_INT: load = new LoadINode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
969 case T_CHAR: load = new LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
970 case T_SHORT: load = new LoadSNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
971 case T_LONG: load = new LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency, require_atomic_access); break;
972 case T_FLOAT: load = new LoadFNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); break;
973 case T_DOUBLE: load = new LoadDNode (ctl, mem, adr, adr_type, rt, mo, control_dependency, require_atomic_access); break;
974 case T_ADDRESS: load = new LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency); break;
975 case T_OBJECT:
976 case T_NARROWOOP:
977 #ifdef _LP64
978 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
979 load = new LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo, control_dependency);
980 } else
981 #endif
982 {
983 assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop");
984 load = new LoadPNode(ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency);
985 }
986 break;
987 default:
988 ShouldNotReachHere();
989 break;
990 }
991 assert(load != nullptr, "LoadNode should have been created");
992 if (unaligned) {
993 load->set_unaligned_access();
994 }
995 if (mismatched) {
996 load->set_mismatched_access();
997 }
998 if (unsafe) {
999 load->set_unsafe_access();
1000 }
1001 load->set_barrier_data(barrier_data);
1002 if (load->Opcode() == Op_LoadN) {
1003 Node* ld = gvn.transform(load);
1004 return new DecodeNNode(ld, ld->bottom_type()->make_ptr());
1005 }
1006
1007 return load;
1008 }
1009
1010 //------------------------------hash-------------------------------------------
1011 uint LoadNode::hash() const {
1012 // unroll addition of interesting fields
1013 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
1014 }
1015
1016 static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) {
1017 if ((atp != nullptr) && (atp->index() >= Compile::AliasIdxRaw)) {
1018 bool non_volatile = (atp->field() != nullptr) && !atp->field()->is_volatile();
1019 bool is_stable_ary = FoldStableValues &&
1020 (tp != nullptr) && (tp->isa_aryptr() != nullptr) &&
1021 tp->isa_aryptr()->is_stable();
1022
1023 return (eliminate_boxing && non_volatile) || is_stable_ary;
1024 }
1025
1026 return false;
1027 }
1028
1029 LoadNode* LoadNode::pin_array_access_node() const {
1030 const TypePtr* adr_type = this->adr_type();
1031 if (adr_type != nullptr && adr_type->isa_aryptr()) {
1032 return clone_pinned();
1033 }
1034 return nullptr;
1035 }
1036
1037 // Is the value loaded previously stored by an arraycopy? If so return
1038 // a load node that reads from the source array so we may be able to
1039 // optimize out the ArrayCopy node later.
1040 Node* LoadNode::can_see_arraycopy_value(Node* st, PhaseGVN* phase) const {
1041 Node* ld_adr = in(MemNode::Address);
1042 intptr_t ld_off = 0;
1043 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
1044 Node* ac = find_previous_arraycopy(phase, ld_alloc, st, true);
1045 if (ac != nullptr) {
1046 assert(ac->is_ArrayCopy(), "what kind of node can this be?");
1047
1048 Node* mem = ac->in(TypeFunc::Memory);
1049 Node* ctl = ac->in(0);
1050 Node* src = ac->in(ArrayCopyNode::Src);
1051
1052 if (!ac->as_ArrayCopy()->is_clonebasic() && !phase->type(src)->isa_aryptr()) {
1053 return nullptr;
1054 }
1055
1056 // load depends on the tests that validate the arraycopy
1057 LoadNode* ld = clone_pinned();
1058 Node* addp = in(MemNode::Address)->clone();
1059 if (ac->as_ArrayCopy()->is_clonebasic()) {
1060 assert(ld_alloc != nullptr, "need an alloc");
1061 assert(addp->is_AddP(), "address must be addp");
1062 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1063 assert(bs->step_over_gc_barrier(addp->in(AddPNode::Base)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)), "strange pattern");
1064 assert(bs->step_over_gc_barrier(addp->in(AddPNode::Address)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)), "strange pattern");
1065 addp->set_req(AddPNode::Base, src);
1066 addp->set_req(AddPNode::Address, src);
1067 } else {
1068 assert(ac->as_ArrayCopy()->is_arraycopy_validated() ||
1069 ac->as_ArrayCopy()->is_copyof_validated() ||
1070 ac->as_ArrayCopy()->is_copyofrange_validated(), "only supported cases");
1071 assert(addp->in(AddPNode::Base) == addp->in(AddPNode::Address), "should be");
1072 addp->set_req(AddPNode::Base, src);
1073 addp->set_req(AddPNode::Address, src);
1074
1075 const TypeAryPtr* ary_t = phase->type(in(MemNode::Address))->isa_aryptr();
1076 BasicType ary_elem = ary_t->isa_aryptr()->elem()->array_element_basic_type();
1077 if (is_reference_type(ary_elem, true)) ary_elem = T_OBJECT;
1078
1079 uint header = arrayOopDesc::base_offset_in_bytes(ary_elem);
1080 uint shift = exact_log2(type2aelembytes(ary_elem));
1081
1082 Node* diff = phase->transform(new SubINode(ac->in(ArrayCopyNode::SrcPos), ac->in(ArrayCopyNode::DestPos)));
1083 #ifdef _LP64
1084 diff = phase->transform(new ConvI2LNode(diff));
1085 #endif
1086 diff = phase->transform(new LShiftXNode(diff, phase->intcon(shift)));
1087
1088 Node* offset = phase->transform(new AddXNode(addp->in(AddPNode::Offset), diff));
1089 addp->set_req(AddPNode::Offset, offset);
1090 }
1091 addp = phase->transform(addp);
1092 #ifdef ASSERT
1093 const TypePtr* adr_type = phase->type(addp)->is_ptr();
1094 ld->_adr_type = adr_type;
1095 #endif
1096 ld->set_req(MemNode::Address, addp);
1097 ld->set_req(0, ctl);
1098 ld->set_req(MemNode::Memory, mem);
1099 return ld;
1100 }
1101 return nullptr;
1102 }
1103
1104
1105 //---------------------------can_see_stored_value------------------------------
1106 // This routine exists to make sure this set of tests is done the same
1107 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
1108 // will change the graph shape in a way which makes memory alive twice at the
1109 // same time (uses the Oracle model of aliasing), then some
1110 // LoadXNode::Identity will fold things back to the equivalence-class model
1111 // of aliasing.
1112 Node* MemNode::can_see_stored_value(Node* st, PhaseValues* phase) const {
1113 Node* ld_adr = in(MemNode::Address);
1114 intptr_t ld_off = 0;
1115 Node* ld_base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ld_off);
1116 Node* ld_alloc = AllocateNode::Ideal_allocation(ld_base);
1117 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
1118 Compile::AliasType* atp = (tp != nullptr) ? phase->C->alias_type(tp) : nullptr;
1119 // This is more general than load from boxing objects.
1120 if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) {
1121 uint alias_idx = atp->index();
1122 Node* result = nullptr;
1123 Node* current = st;
1124 // Skip through chains of MemBarNodes checking the MergeMems for
1125 // new states for the slice of this load. Stop once any other
1126 // kind of node is encountered. Loads from final memory can skip
1127 // through any kind of MemBar but normal loads shouldn't skip
1128 // through MemBarAcquire since the could allow them to move out of
1129 // a synchronized region. It is not safe to step over MemBarCPUOrder,
1130 // because alias info above them may be inaccurate (e.g., due to
1131 // mixed/mismatched unsafe accesses).
1132 bool is_final_mem = !atp->is_rewritable();
1133 while (current->is_Proj()) {
1134 int opc = current->in(0)->Opcode();
1135 if ((is_final_mem && (opc == Op_MemBarAcquire ||
1136 opc == Op_MemBarAcquireLock ||
1137 opc == Op_LoadFence)) ||
1138 opc == Op_MemBarRelease ||
1139 opc == Op_StoreFence ||
1140 opc == Op_MemBarReleaseLock ||
1141 opc == Op_MemBarStoreStore ||
1142 opc == Op_StoreStoreFence) {
1143 Node* mem = current->in(0)->in(TypeFunc::Memory);
1144 if (mem->is_MergeMem()) {
1145 MergeMemNode* merge = mem->as_MergeMem();
1146 Node* new_st = merge->memory_at(alias_idx);
1147 if (new_st == merge->base_memory()) {
1148 // Keep searching
1149 current = new_st;
1150 continue;
1151 }
1152 // Save the new memory state for the slice and fall through
1153 // to exit.
1154 result = new_st;
1155 }
1156 }
1157 break;
1158 }
1159 if (result != nullptr) {
1160 st = result;
1161 }
1162 }
1163
1164 // Loop around twice in the case Load -> Initialize -> Store.
1165 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
1166 for (int trip = 0; trip <= 1; trip++) {
1167
1168 if (st->is_Store()) {
1169 Node* st_adr = st->in(MemNode::Address);
1170 if (st_adr != ld_adr) {
1171 // Try harder before giving up. Unify base pointers with casts (e.g., raw/non-raw pointers).
1172 intptr_t st_off = 0;
1173 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_off);
1174 if (ld_base == nullptr) return nullptr;
1175 if (st_base == nullptr) return nullptr;
1176 if (!ld_base->eqv_uncast(st_base, /*keep_deps=*/true)) return nullptr;
1177 if (ld_off != st_off) return nullptr;
1178 if (ld_off == Type::OffsetBot) return nullptr;
1179 // Same base, same offset.
1180 // Possible improvement for arrays: check index value instead of absolute offset.
1181
1182 // At this point we have proven something like this setup:
1183 // B = << base >>
1184 // L = LoadQ(AddP(Check/CastPP(B), #Off))
1185 // S = StoreQ(AddP( B , #Off), V)
1186 // (Actually, we haven't yet proven the Q's are the same.)
1187 // In other words, we are loading from a casted version of
1188 // the same pointer-and-offset that we stored to.
1189 // Casted version may carry a dependency and it is respected.
1190 // Thus, we are able to replace L by V.
1191 }
1192 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
1193 if (store_Opcode() != st->Opcode()) {
1194 return nullptr;
1195 }
1196 // LoadVector/StoreVector needs additional check to ensure the types match.
1197 if (st->is_StoreVector()) {
1198 const TypeVect* in_vt = st->as_StoreVector()->vect_type();
1199 const TypeVect* out_vt = as_LoadVector()->vect_type();
1200 if (in_vt != out_vt) {
1201 return nullptr;
1202 }
1203 }
1204 return st->in(MemNode::ValueIn);
1205 }
1206
1207 // A load from a freshly-created object always returns zero.
1208 // (This can happen after LoadNode::Ideal resets the load's memory input
1209 // to find_captured_store, which returned InitializeNode::zero_memory.)
1210 if (st->is_Proj() && st->in(0)->is_Allocate() &&
1211 (st->in(0) == ld_alloc) &&
1212 (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) {
1213 // return a zero value for the load's basic type
1214 // (This is one of the few places where a generic PhaseTransform
1215 // can create new nodes. Think of it as lazily manifesting
1216 // virtually pre-existing constants.)
1217 if (value_basic_type() != T_VOID) {
1218 if (ReduceBulkZeroing || find_array_copy_clone(ld_alloc, in(MemNode::Memory)) == nullptr) {
1219 // If ReduceBulkZeroing is disabled, we need to check if the allocation does not belong to an
1220 // ArrayCopyNode clone. If it does, then we cannot assume zero since the initialization is done
1221 // by the ArrayCopyNode.
1222 return phase->zerocon(value_basic_type());
1223 }
1224 } else {
1225 // TODO: materialize all-zero vector constant
1226 assert(!isa_Load() || as_Load()->type()->isa_vect(), "");
1227 }
1228 }
1229
1230 // A load from an initialization barrier can match a captured store.
1231 if (st->is_Proj() && st->in(0)->is_Initialize()) {
1232 InitializeNode* init = st->in(0)->as_Initialize();
1233 AllocateNode* alloc = init->allocation();
1234 if ((alloc != nullptr) && (alloc == ld_alloc)) {
1235 // examine a captured store value
1236 st = init->find_captured_store(ld_off, memory_size(), phase);
1237 if (st != nullptr) {
1238 continue; // take one more trip around
1239 }
1240 }
1241 }
1242
1243 // Load boxed value from result of valueOf() call is input parameter.
1244 if (this->is_Load() && ld_adr->is_AddP() &&
1245 (tp != nullptr) && tp->is_ptr_to_boxed_value()) {
1246 intptr_t ignore = 0;
1247 Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore);
1248 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1249 base = bs->step_over_gc_barrier(base);
1250 if (base != nullptr && base->is_Proj() &&
1251 base->as_Proj()->_con == TypeFunc::Parms &&
1252 base->in(0)->is_CallStaticJava() &&
1253 base->in(0)->as_CallStaticJava()->is_boxing_method()) {
1254 return base->in(0)->in(TypeFunc::Parms);
1255 }
1256 }
1257
1258 break;
1259 }
1260
1261 return nullptr;
1262 }
1263
1264 //----------------------is_instance_field_load_with_local_phi------------------
1265 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
1266 if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl &&
1267 in(Address)->is_AddP() ) {
1268 const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr();
1269 // Only instances and boxed values.
1270 if( t_oop != nullptr &&
1271 (t_oop->is_ptr_to_boxed_value() ||
1272 t_oop->is_known_instance_field()) &&
1273 t_oop->offset() != Type::OffsetBot &&
1274 t_oop->offset() != Type::OffsetTop) {
1275 return true;
1276 }
1277 }
1278 return false;
1279 }
1280
1281 //------------------------------Identity---------------------------------------
1282 // Loads are identity if previous store is to same address
1283 Node* LoadNode::Identity(PhaseGVN* phase) {
1284 // If the previous store-maker is the right kind of Store, and the store is
1285 // to the same address, then we are equal to the value stored.
1286 Node* mem = in(Memory);
1287 Node* value = can_see_stored_value(mem, phase);
1288 if( value ) {
1289 // byte, short & char stores truncate naturally.
1290 // A load has to load the truncated value which requires
1291 // some sort of masking operation and that requires an
1292 // Ideal call instead of an Identity call.
1293 if (memory_size() < BytesPerInt) {
1294 // If the input to the store does not fit with the load's result type,
1295 // it must be truncated via an Ideal call.
1296 if (!phase->type(value)->higher_equal(phase->type(this)))
1297 return this;
1298 }
1299 // (This works even when value is a Con, but LoadNode::Value
1300 // usually runs first, producing the singleton type of the Con.)
1301 if (!has_pinned_control_dependency() || value->is_Con()) {
1302 return value;
1303 } else {
1304 return this;
1305 }
1306 }
1307
1308 if (has_pinned_control_dependency()) {
1309 return this;
1310 }
1311 // Search for an existing data phi which was generated before for the same
1312 // instance's field to avoid infinite generation of phis in a loop.
1313 Node *region = mem->in(0);
1314 if (is_instance_field_load_with_local_phi(region)) {
1315 const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr();
1316 int this_index = phase->C->get_alias_index(addr_t);
1317 int this_offset = addr_t->offset();
1318 int this_iid = addr_t->instance_id();
1319 if (!addr_t->is_known_instance() &&
1320 addr_t->is_ptr_to_boxed_value()) {
1321 // Use _idx of address base (could be Phi node) for boxed values.
1322 intptr_t ignore = 0;
1323 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1324 if (base == nullptr) {
1325 return this;
1326 }
1327 this_iid = base->_idx;
1328 }
1329 const Type* this_type = bottom_type();
1330 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1331 Node* phi = region->fast_out(i);
1332 if (phi->is_Phi() && phi != mem &&
1333 phi->as_Phi()->is_same_inst_field(this_type, (int)mem->_idx, this_iid, this_index, this_offset)) {
1334 return phi;
1335 }
1336 }
1337 }
1338
1339 return this;
1340 }
1341
1342 // Construct an equivalent unsigned load.
1343 Node* LoadNode::convert_to_unsigned_load(PhaseGVN& gvn) {
1344 BasicType bt = T_ILLEGAL;
1345 const Type* rt = nullptr;
1346 switch (Opcode()) {
1347 case Op_LoadUB: return this;
1348 case Op_LoadUS: return this;
1349 case Op_LoadB: bt = T_BOOLEAN; rt = TypeInt::UBYTE; break;
1350 case Op_LoadS: bt = T_CHAR; rt = TypeInt::CHAR; break;
1351 default:
1352 assert(false, "no unsigned variant: %s", Name());
1353 return nullptr;
1354 }
1355 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1356 raw_adr_type(), rt, bt, _mo, _control_dependency,
1357 false /*require_atomic_access*/, is_unaligned_access(), is_mismatched_access());
1358 }
1359
1360 // Construct an equivalent signed load.
1361 Node* LoadNode::convert_to_signed_load(PhaseGVN& gvn) {
1362 BasicType bt = T_ILLEGAL;
1363 const Type* rt = nullptr;
1364 switch (Opcode()) {
1365 case Op_LoadUB: bt = T_BYTE; rt = TypeInt::BYTE; break;
1366 case Op_LoadUS: bt = T_SHORT; rt = TypeInt::SHORT; break;
1367 case Op_LoadB: // fall through
1368 case Op_LoadS: // fall through
1369 case Op_LoadI: // fall through
1370 case Op_LoadL: return this;
1371 default:
1372 assert(false, "no signed variant: %s", Name());
1373 return nullptr;
1374 }
1375 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1376 raw_adr_type(), rt, bt, _mo, _control_dependency,
1377 false /*require_atomic_access*/, is_unaligned_access(), is_mismatched_access());
1378 }
1379
1380 bool LoadNode::has_reinterpret_variant(const Type* rt) {
1381 BasicType bt = rt->basic_type();
1382 switch (Opcode()) {
1383 case Op_LoadI: return (bt == T_FLOAT);
1384 case Op_LoadL: return (bt == T_DOUBLE);
1385 case Op_LoadF: return (bt == T_INT);
1386 case Op_LoadD: return (bt == T_LONG);
1387
1388 default: return false;
1389 }
1390 }
1391
1392 Node* LoadNode::convert_to_reinterpret_load(PhaseGVN& gvn, const Type* rt) {
1393 BasicType bt = rt->basic_type();
1394 assert(has_reinterpret_variant(rt), "no reinterpret variant: %s %s", Name(), type2name(bt));
1395 bool is_mismatched = is_mismatched_access();
1396 const TypeRawPtr* raw_type = gvn.type(in(MemNode::Memory))->isa_rawptr();
1397 if (raw_type == nullptr) {
1398 is_mismatched = true; // conservatively match all non-raw accesses as mismatched
1399 }
1400 const int op = Opcode();
1401 bool require_atomic_access = (op == Op_LoadL && ((LoadLNode*)this)->require_atomic_access()) ||
1402 (op == Op_LoadD && ((LoadDNode*)this)->require_atomic_access());
1403 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1404 raw_adr_type(), rt, bt, _mo, _control_dependency,
1405 require_atomic_access, is_unaligned_access(), is_mismatched);
1406 }
1407
1408 bool StoreNode::has_reinterpret_variant(const Type* vt) {
1409 BasicType bt = vt->basic_type();
1410 switch (Opcode()) {
1411 case Op_StoreI: return (bt == T_FLOAT);
1412 case Op_StoreL: return (bt == T_DOUBLE);
1413 case Op_StoreF: return (bt == T_INT);
1414 case Op_StoreD: return (bt == T_LONG);
1415
1416 default: return false;
1417 }
1418 }
1419
1420 Node* StoreNode::convert_to_reinterpret_store(PhaseGVN& gvn, Node* val, const Type* vt) {
1421 BasicType bt = vt->basic_type();
1422 assert(has_reinterpret_variant(vt), "no reinterpret variant: %s %s", Name(), type2name(bt));
1423 const int op = Opcode();
1424 bool require_atomic_access = (op == Op_StoreL && ((StoreLNode*)this)->require_atomic_access()) ||
1425 (op == Op_StoreD && ((StoreDNode*)this)->require_atomic_access());
1426 StoreNode* st = StoreNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1427 raw_adr_type(), val, bt, _mo, require_atomic_access);
1428
1429 bool is_mismatched = is_mismatched_access();
1430 const TypeRawPtr* raw_type = gvn.type(in(MemNode::Memory))->isa_rawptr();
1431 if (raw_type == nullptr) {
1432 is_mismatched = true; // conservatively match all non-raw accesses as mismatched
1433 }
1434 if (is_mismatched) {
1435 st->set_mismatched_access();
1436 }
1437 return st;
1438 }
1439
1440 // We're loading from an object which has autobox behaviour.
1441 // If this object is result of a valueOf call we'll have a phi
1442 // merging a newly allocated object and a load from the cache.
1443 // We want to replace this load with the original incoming
1444 // argument to the valueOf call.
1445 Node* LoadNode::eliminate_autobox(PhaseIterGVN* igvn) {
1446 assert(igvn->C->eliminate_boxing(), "sanity");
1447 intptr_t ignore = 0;
1448 Node* base = AddPNode::Ideal_base_and_offset(in(Address), igvn, ignore);
1449 if ((base == nullptr) || base->is_Phi()) {
1450 // Push the loads from the phi that comes from valueOf up
1451 // through it to allow elimination of the loads and the recovery
1452 // of the original value. It is done in split_through_phi().
1453 return nullptr;
1454 } else if (base->is_Load() ||
1455 (base->is_DecodeN() && base->in(1)->is_Load())) {
1456 // Eliminate the load of boxed value for integer types from the cache
1457 // array by deriving the value from the index into the array.
1458 // Capture the offset of the load and then reverse the computation.
1459
1460 // Get LoadN node which loads a boxing object from 'cache' array.
1461 if (base->is_DecodeN()) {
1462 base = base->in(1);
1463 }
1464 if (!base->in(Address)->is_AddP()) {
1465 return nullptr; // Complex address
1466 }
1467 AddPNode* address = base->in(Address)->as_AddP();
1468 Node* cache_base = address->in(AddPNode::Base);
1469 if ((cache_base != nullptr) && cache_base->is_DecodeN()) {
1470 // Get ConP node which is static 'cache' field.
1471 cache_base = cache_base->in(1);
1472 }
1473 if ((cache_base != nullptr) && cache_base->is_Con()) {
1474 const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr();
1475 if ((base_type != nullptr) && base_type->is_autobox_cache()) {
1476 Node* elements[4];
1477 int shift = exact_log2(type2aelembytes(T_OBJECT));
1478 int count = address->unpack_offsets(elements, ARRAY_SIZE(elements));
1479 if (count > 0 && elements[0]->is_Con() &&
1480 (count == 1 ||
1481 (count == 2 && elements[1]->Opcode() == Op_LShiftX &&
1482 elements[1]->in(2) == igvn->intcon(shift)))) {
1483 ciObjArray* array = base_type->const_oop()->as_obj_array();
1484 // Fetch the box object cache[0] at the base of the array and get its value
1485 ciInstance* box = array->obj_at(0)->as_instance();
1486 ciInstanceKlass* ik = box->klass()->as_instance_klass();
1487 assert(ik->is_box_klass(), "sanity");
1488 assert(ik->nof_nonstatic_fields() == 1, "change following code");
1489 if (ik->nof_nonstatic_fields() == 1) {
1490 // This should be true nonstatic_field_at requires calling
1491 // nof_nonstatic_fields so check it anyway
1492 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1493 BasicType bt = c.basic_type();
1494 // Only integer types have boxing cache.
1495 assert(bt == T_BOOLEAN || bt == T_CHAR ||
1496 bt == T_BYTE || bt == T_SHORT ||
1497 bt == T_INT || bt == T_LONG, "wrong type = %s", type2name(bt));
1498 jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int();
1499 if (cache_low != (int)cache_low) {
1500 return nullptr; // should not happen since cache is array indexed by value
1501 }
1502 jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift);
1503 if (offset != (int)offset) {
1504 return nullptr; // should not happen since cache is array indexed by value
1505 }
1506 // Add up all the offsets making of the address of the load
1507 Node* result = elements[0];
1508 for (int i = 1; i < count; i++) {
1509 result = igvn->transform(new AddXNode(result, elements[i]));
1510 }
1511 // Remove the constant offset from the address and then
1512 result = igvn->transform(new AddXNode(result, igvn->MakeConX(-(int)offset)));
1513 // remove the scaling of the offset to recover the original index.
1514 if (result->Opcode() == Op_LShiftX && result->in(2) == igvn->intcon(shift)) {
1515 // Peel the shift off directly but wrap it in a dummy node
1516 // since Ideal can't return existing nodes
1517 igvn->_worklist.push(result); // remove dead node later
1518 result = new RShiftXNode(result->in(1), igvn->intcon(0));
1519 } else if (result->is_Add() && result->in(2)->is_Con() &&
1520 result->in(1)->Opcode() == Op_LShiftX &&
1521 result->in(1)->in(2) == igvn->intcon(shift)) {
1522 // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z)
1523 // but for boxing cache access we know that X<<Z will not overflow
1524 // (there is range check) so we do this optimizatrion by hand here.
1525 igvn->_worklist.push(result); // remove dead node later
1526 Node* add_con = new RShiftXNode(result->in(2), igvn->intcon(shift));
1527 result = new AddXNode(result->in(1)->in(1), igvn->transform(add_con));
1528 } else {
1529 result = new RShiftXNode(result, igvn->intcon(shift));
1530 }
1531 #ifdef _LP64
1532 if (bt != T_LONG) {
1533 result = new ConvL2INode(igvn->transform(result));
1534 }
1535 #else
1536 if (bt == T_LONG) {
1537 result = new ConvI2LNode(igvn->transform(result));
1538 }
1539 #endif
1540 // Boxing/unboxing can be done from signed & unsigned loads (e.g. LoadUB -> ... -> LoadB pair).
1541 // Need to preserve unboxing load type if it is unsigned.
1542 switch(this->Opcode()) {
1543 case Op_LoadUB:
1544 result = new AndINode(igvn->transform(result), igvn->intcon(0xFF));
1545 break;
1546 case Op_LoadUS:
1547 result = new AndINode(igvn->transform(result), igvn->intcon(0xFFFF));
1548 break;
1549 }
1550 return result;
1551 }
1552 }
1553 }
1554 }
1555 }
1556 return nullptr;
1557 }
1558
1559 static bool stable_phi(PhiNode* phi, PhaseGVN *phase) {
1560 Node* region = phi->in(0);
1561 if (region == nullptr) {
1562 return false; // Wait stable graph
1563 }
1564 uint cnt = phi->req();
1565 for (uint i = 1; i < cnt; i++) {
1566 Node* rc = region->in(i);
1567 if (rc == nullptr || phase->type(rc) == Type::TOP)
1568 return false; // Wait stable graph
1569 Node* in = phi->in(i);
1570 if (in == nullptr || phase->type(in) == Type::TOP)
1571 return false; // Wait stable graph
1572 }
1573 return true;
1574 }
1575
1576 //------------------------------split_through_phi------------------------------
1577 // Check whether a call to 'split_through_phi' would split this load through the
1578 // Phi *base*. This method is essentially a copy of the validations performed
1579 // by 'split_through_phi'. The first use of this method was in EA code as part
1580 // of simplification of allocation merges.
1581 // Some differences from original method (split_through_phi):
1582 // - If base->is_CastPP(): base = base->in(1)
1583 bool LoadNode::can_split_through_phi_base(PhaseGVN* phase) {
1584 Node* mem = in(Memory);
1585 Node* address = in(Address);
1586 intptr_t ignore = 0;
1587 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1588
1589 if (base->is_CastPP()) {
1590 base = base->in(1);
1591 }
1592
1593 if (req() > 3 || base == nullptr || !base->is_Phi()) {
1594 return false;
1595 }
1596
1597 if (!mem->is_Phi()) {
1598 if (!MemNode::all_controls_dominate(mem, base->in(0))) {
1599 return false;
1600 }
1601 } else if (base->in(0) != mem->in(0)) {
1602 if (!MemNode::all_controls_dominate(mem, base->in(0))) {
1603 return false;
1604 }
1605 }
1606
1607 return true;
1608 }
1609
1610 //------------------------------split_through_phi------------------------------
1611 // Split instance or boxed field load through Phi.
1612 Node* LoadNode::split_through_phi(PhaseGVN* phase, bool ignore_missing_instance_id) {
1613 if (req() > 3) {
1614 assert(is_LoadVector() && Opcode() != Op_LoadVector, "load has too many inputs");
1615 // LoadVector subclasses such as LoadVectorMasked have extra inputs that the logic below doesn't take into account
1616 return nullptr;
1617 }
1618 Node* mem = in(Memory);
1619 Node* address = in(Address);
1620 const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr();
1621
1622 assert((t_oop != nullptr) &&
1623 (ignore_missing_instance_id ||
1624 t_oop->is_known_instance_field() ||
1625 t_oop->is_ptr_to_boxed_value()), "invalid conditions");
1626
1627 Compile* C = phase->C;
1628 intptr_t ignore = 0;
1629 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1630 bool base_is_phi = (base != nullptr) && base->is_Phi();
1631 bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() &&
1632 (base != nullptr) && (base == address->in(AddPNode::Base)) &&
1633 phase->type(base)->higher_equal(TypePtr::NOTNULL);
1634
1635 if (!((mem->is_Phi() || base_is_phi) &&
1636 (ignore_missing_instance_id || load_boxed_values || t_oop->is_known_instance_field()))) {
1637 return nullptr; // Neither memory or base are Phi
1638 }
1639
1640 if (mem->is_Phi()) {
1641 if (!stable_phi(mem->as_Phi(), phase)) {
1642 return nullptr; // Wait stable graph
1643 }
1644 uint cnt = mem->req();
1645 // Check for loop invariant memory.
1646 if (cnt == 3) {
1647 for (uint i = 1; i < cnt; i++) {
1648 Node* in = mem->in(i);
1649 Node* m = optimize_memory_chain(in, t_oop, this, phase);
1650 if (m == mem) {
1651 if (i == 1) {
1652 // if the first edge was a loop, check second edge too.
1653 // If both are replaceable - we are in an infinite loop
1654 Node *n = optimize_memory_chain(mem->in(2), t_oop, this, phase);
1655 if (n == mem) {
1656 break;
1657 }
1658 }
1659 set_req(Memory, mem->in(cnt - i));
1660 return this; // made change
1661 }
1662 }
1663 }
1664 }
1665 if (base_is_phi) {
1666 if (!stable_phi(base->as_Phi(), phase)) {
1667 return nullptr; // Wait stable graph
1668 }
1669 uint cnt = base->req();
1670 // Check for loop invariant memory.
1671 if (cnt == 3) {
1672 for (uint i = 1; i < cnt; i++) {
1673 if (base->in(i) == base) {
1674 return nullptr; // Wait stable graph
1675 }
1676 }
1677 }
1678 }
1679
1680 // Split through Phi (see original code in loopopts.cpp).
1681 assert(ignore_missing_instance_id || C->have_alias_type(t_oop), "instance should have alias type");
1682
1683 // Do nothing here if Identity will find a value
1684 // (to avoid infinite chain of value phis generation).
1685 if (this != Identity(phase)) {
1686 return nullptr;
1687 }
1688
1689 // Select Region to split through.
1690 Node* region;
1691 DomResult dom_result = DomResult::Dominate;
1692 if (!base_is_phi) {
1693 assert(mem->is_Phi(), "sanity");
1694 region = mem->in(0);
1695 // Skip if the region dominates some control edge of the address.
1696 // We will check `dom_result` later.
1697 dom_result = MemNode::maybe_all_controls_dominate(address, region);
1698 } else if (!mem->is_Phi()) {
1699 assert(base_is_phi, "sanity");
1700 region = base->in(0);
1701 // Skip if the region dominates some control edge of the memory.
1702 // We will check `dom_result` later.
1703 dom_result = MemNode::maybe_all_controls_dominate(mem, region);
1704 } else if (base->in(0) != mem->in(0)) {
1705 assert(base_is_phi && mem->is_Phi(), "sanity");
1706 dom_result = MemNode::maybe_all_controls_dominate(mem, base->in(0));
1707 if (dom_result == DomResult::Dominate) {
1708 region = base->in(0);
1709 } else {
1710 dom_result = MemNode::maybe_all_controls_dominate(address, mem->in(0));
1711 if (dom_result == DomResult::Dominate) {
1712 region = mem->in(0);
1713 }
1714 // Otherwise we encountered a complex graph.
1715 }
1716 } else {
1717 assert(base->in(0) == mem->in(0), "sanity");
1718 region = mem->in(0);
1719 }
1720
1721 PhaseIterGVN* igvn = phase->is_IterGVN();
1722 if (dom_result != DomResult::Dominate) {
1723 if (dom_result == DomResult::EncounteredDeadCode) {
1724 // There is some dead code which eventually will be removed in IGVN.
1725 // Once this is the case, we get an unambiguous dominance result.
1726 // Push the node to the worklist again until the dead code is removed.
1727 igvn->_worklist.push(this);
1728 }
1729 return nullptr;
1730 }
1731
1732 Node* phi = nullptr;
1733 const Type* this_type = this->bottom_type();
1734 if (t_oop != nullptr && (t_oop->is_known_instance_field() || load_boxed_values)) {
1735 int this_index = C->get_alias_index(t_oop);
1736 int this_offset = t_oop->offset();
1737 int this_iid = t_oop->is_known_instance_field() ? t_oop->instance_id() : base->_idx;
1738 phi = new PhiNode(region, this_type, nullptr, mem->_idx, this_iid, this_index, this_offset);
1739 } else if (ignore_missing_instance_id) {
1740 phi = new PhiNode(region, this_type, nullptr, mem->_idx);
1741 } else {
1742 return nullptr;
1743 }
1744
1745 for (uint i = 1; i < region->req(); i++) {
1746 Node* x;
1747 Node* the_clone = nullptr;
1748 Node* in = region->in(i);
1749 if (region->is_CountedLoop() && region->as_Loop()->is_strip_mined() && i == LoopNode::EntryControl &&
1750 in != nullptr && in->is_OuterStripMinedLoop()) {
1751 // No node should go in the outer strip mined loop
1752 in = in->in(LoopNode::EntryControl);
1753 }
1754 if (in == nullptr || in == C->top()) {
1755 x = C->top(); // Dead path? Use a dead data op
1756 } else {
1757 x = this->clone(); // Else clone up the data op
1758 the_clone = x; // Remember for possible deletion.
1759 // Alter data node to use pre-phi inputs
1760 if (this->in(0) == region) {
1761 x->set_req(0, in);
1762 } else {
1763 x->set_req(0, nullptr);
1764 }
1765 if (mem->is_Phi() && (mem->in(0) == region)) {
1766 x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone.
1767 }
1768 if (address->is_Phi() && address->in(0) == region) {
1769 x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone
1770 }
1771 if (base_is_phi && (base->in(0) == region)) {
1772 Node* base_x = base->in(i); // Clone address for loads from boxed objects.
1773 Node* adr_x = phase->transform(new AddPNode(base_x,base_x,address->in(AddPNode::Offset)));
1774 x->set_req(Address, adr_x);
1775 }
1776 }
1777 // Check for a 'win' on some paths
1778 const Type *t = x->Value(igvn);
1779
1780 bool singleton = t->singleton();
1781
1782 // See comments in PhaseIdealLoop::split_thru_phi().
1783 if (singleton && t == Type::TOP) {
1784 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1785 }
1786
1787 if (singleton) {
1788 x = igvn->makecon(t);
1789 } else {
1790 // We now call Identity to try to simplify the cloned node.
1791 // Note that some Identity methods call phase->type(this).
1792 // Make sure that the type array is big enough for
1793 // our new node, even though we may throw the node away.
1794 // (This tweaking with igvn only works because x is a new node.)
1795 igvn->set_type(x, t);
1796 // If x is a TypeNode, capture any more-precise type permanently into Node
1797 // otherwise it will be not updated during igvn->transform since
1798 // igvn->type(x) is set to x->Value() already.
1799 x->raise_bottom_type(t);
1800 Node* y = x->Identity(igvn);
1801 if (y != x) {
1802 x = y;
1803 } else {
1804 y = igvn->hash_find_insert(x);
1805 if (y) {
1806 x = y;
1807 } else {
1808 // Else x is a new node we are keeping
1809 // We do not need register_new_node_with_optimizer
1810 // because set_type has already been called.
1811 igvn->_worklist.push(x);
1812 }
1813 }
1814 }
1815 if (x != the_clone && the_clone != nullptr) {
1816 igvn->remove_dead_node(the_clone);
1817 }
1818 phi->set_req(i, x);
1819 }
1820 // Record Phi
1821 igvn->register_new_node_with_optimizer(phi);
1822 return phi;
1823 }
1824
1825 AllocateNode* LoadNode::is_new_object_mark_load() const {
1826 if (Opcode() == Op_LoadX) {
1827 Node* address = in(MemNode::Address);
1828 AllocateNode* alloc = AllocateNode::Ideal_allocation(address);
1829 Node* mem = in(MemNode::Memory);
1830 if (alloc != nullptr && mem->is_Proj() &&
1831 mem->in(0) != nullptr &&
1832 mem->in(0) == alloc->initialization() &&
1833 alloc->initialization()->proj_out_or_null(0) != nullptr) {
1834 return alloc;
1835 }
1836 }
1837 return nullptr;
1838 }
1839
1840
1841 //------------------------------Ideal------------------------------------------
1842 // If the load is from Field memory and the pointer is non-null, it might be possible to
1843 // zero out the control input.
1844 // If the offset is constant and the base is an object allocation,
1845 // try to hook me up to the exact initializing store.
1846 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1847 if (has_pinned_control_dependency()) {
1848 return nullptr;
1849 }
1850 Node* p = MemNode::Ideal_common(phase, can_reshape);
1851 if (p) return (p == NodeSentinel) ? nullptr : p;
1852
1853 Node* ctrl = in(MemNode::Control);
1854 Node* address = in(MemNode::Address);
1855 bool progress = false;
1856
1857 bool addr_mark = ((phase->type(address)->isa_oopptr() || phase->type(address)->isa_narrowoop()) &&
1858 phase->type(address)->is_ptr()->offset() == oopDesc::mark_offset_in_bytes());
1859
1860 // Skip up past a SafePoint control. Cannot do this for Stores because
1861 // pointer stores & cardmarks must stay on the same side of a SafePoint.
1862 if( ctrl != nullptr && ctrl->Opcode() == Op_SafePoint &&
1863 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw &&
1864 !addr_mark &&
1865 (depends_only_on_test() || has_unknown_control_dependency())) {
1866 ctrl = ctrl->in(0);
1867 set_req(MemNode::Control,ctrl);
1868 progress = true;
1869 }
1870
1871 intptr_t ignore = 0;
1872 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1873 if (base != nullptr
1874 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
1875 // Check for useless control edge in some common special cases
1876 if (in(MemNode::Control) != nullptr
1877 && can_remove_control()
1878 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1879 && all_controls_dominate(base, phase->C->start())) {
1880 // A method-invariant, non-null address (constant or 'this' argument).
1881 set_req(MemNode::Control, nullptr);
1882 progress = true;
1883 }
1884 }
1885
1886 Node* mem = in(MemNode::Memory);
1887 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1888
1889 if (can_reshape && (addr_t != nullptr)) {
1890 // try to optimize our memory input
1891 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase);
1892 if (opt_mem != mem) {
1893 set_req_X(MemNode::Memory, opt_mem, phase);
1894 if (phase->type( opt_mem ) == Type::TOP) return nullptr;
1895 return this;
1896 }
1897 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1898 if ((t_oop != nullptr) &&
1899 (t_oop->is_known_instance_field() ||
1900 t_oop->is_ptr_to_boxed_value())) {
1901 PhaseIterGVN *igvn = phase->is_IterGVN();
1902 assert(igvn != nullptr, "must be PhaseIterGVN when can_reshape is true");
1903 if (igvn->_worklist.member(opt_mem)) {
1904 // Delay this transformation until memory Phi is processed.
1905 igvn->_worklist.push(this);
1906 return nullptr;
1907 }
1908 // Split instance field load through Phi.
1909 Node* result = split_through_phi(phase);
1910 if (result != nullptr) return result;
1911
1912 if (t_oop->is_ptr_to_boxed_value()) {
1913 Node* result = eliminate_autobox(igvn);
1914 if (result != nullptr) return result;
1915 }
1916 }
1917 }
1918
1919 // Is there a dominating load that loads the same value? Leave
1920 // anything that is not a load of a field/array element (like
1921 // barriers etc.) alone
1922 if (in(0) != nullptr && !adr_type()->isa_rawptr() && can_reshape) {
1923 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) {
1924 Node *use = mem->fast_out(i);
1925 if (use != this &&
1926 use->Opcode() == Opcode() &&
1927 use->in(0) != nullptr &&
1928 use->in(0) != in(0) &&
1929 use->in(Address) == in(Address)) {
1930 Node* ctl = in(0);
1931 for (int i = 0; i < 10 && ctl != nullptr; i++) {
1932 ctl = IfNode::up_one_dom(ctl);
1933 if (ctl == use->in(0)) {
1934 set_req(0, use->in(0));
1935 return this;
1936 }
1937 }
1938 }
1939 }
1940 }
1941
1942 // Check for prior store with a different base or offset; make Load
1943 // independent. Skip through any number of them. Bail out if the stores
1944 // are in an endless dead cycle and report no progress. This is a key
1945 // transform for Reflection. However, if after skipping through the Stores
1946 // we can't then fold up against a prior store do NOT do the transform as
1947 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
1948 // array memory alive twice: once for the hoisted Load and again after the
1949 // bypassed Store. This situation only works if EVERYBODY who does
1950 // anti-dependence work knows how to bypass. I.e. we need all
1951 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
1952 // the alias index stuff. So instead, peek through Stores and IFF we can
1953 // fold up, do so.
1954 Node* prev_mem = find_previous_store(phase);
1955 if (prev_mem != nullptr) {
1956 Node* value = can_see_arraycopy_value(prev_mem, phase);
1957 if (value != nullptr) {
1958 return value;
1959 }
1960 }
1961 // Steps (a), (b): Walk past independent stores to find an exact match.
1962 if (prev_mem != nullptr && prev_mem != in(MemNode::Memory)) {
1963 // (c) See if we can fold up on the spot, but don't fold up here.
1964 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
1965 // just return a prior value, which is done by Identity calls.
1966 if (can_see_stored_value(prev_mem, phase)) {
1967 // Make ready for step (d):
1968 set_req_X(MemNode::Memory, prev_mem, phase);
1969 return this;
1970 }
1971 }
1972
1973 return progress ? this : nullptr;
1974 }
1975
1976 // Helper to recognize certain Klass fields which are invariant across
1977 // some group of array types (e.g., int[] or all T[] where T < Object).
1978 const Type*
1979 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1980 ciKlass* klass) const {
1981 assert(!UseCompactObjectHeaders ||
1982 AOTCodeCache::is_on_for_dump() ||
1983 tkls->offset() != in_bytes(Klass::prototype_header_offset()),
1984 "must not happen");
1985 if (tkls->offset() == in_bytes(Klass::access_flags_offset())) {
1986 // The field is Klass::_access_flags. Return its (constant) value.
1987 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1988 assert(Opcode() == Op_LoadUS, "must load an unsigned short from _access_flags");
1989 return TypeInt::make(klass->access_flags());
1990 }
1991 if (tkls->offset() == in_bytes(Klass::misc_flags_offset())) {
1992 // The field is Klass::_misc_flags. Return its (constant) value.
1993 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1994 assert(Opcode() == Op_LoadUB, "must load an unsigned byte from _misc_flags");
1995 return TypeInt::make(klass->misc_flags());
1996 }
1997 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) {
1998 // The field is Klass::_layout_helper. Return its constant value if known.
1999 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
2000 return TypeInt::make(klass->layout_helper());
2001 }
2002
2003 // No match.
2004 return nullptr;
2005 }
2006
2007 //------------------------------Value-----------------------------------------
2008 const Type* LoadNode::Value(PhaseGVN* phase) const {
2009 // Either input is TOP ==> the result is TOP
2010 Node* mem = in(MemNode::Memory);
2011 const Type *t1 = phase->type(mem);
2012 if (t1 == Type::TOP) return Type::TOP;
2013 Node* adr = in(MemNode::Address);
2014 const TypePtr* tp = phase->type(adr)->isa_ptr();
2015 if (tp == nullptr || tp->empty()) return Type::TOP;
2016 int off = tp->offset();
2017 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
2018 Compile* C = phase->C;
2019
2020 // If we are loading from a freshly-allocated object, produce a zero,
2021 // if the load is provably beyond the header of the object.
2022 // (Also allow a variable load from a fresh array to produce zero.)
2023 const TypeOopPtr* tinst = tp->isa_oopptr();
2024 bool is_instance = (tinst != nullptr) && tinst->is_known_instance_field();
2025 Node* value = can_see_stored_value(mem, phase);
2026 if (value != nullptr && value->is_Con()) {
2027 assert(value->bottom_type()->higher_equal(_type), "sanity");
2028 return value->bottom_type();
2029 }
2030
2031 // Try to guess loaded type from pointer type
2032 if (tp->isa_aryptr()) {
2033 const TypeAryPtr* ary = tp->is_aryptr();
2034 const Type* t = ary->elem();
2035
2036 // Determine whether the reference is beyond the header or not, by comparing
2037 // the offset against the offset of the start of the array's data.
2038 // Different array types begin at slightly different offsets (12 vs. 16).
2039 // We choose T_BYTE as an example base type that is least restrictive
2040 // as to alignment, which will therefore produce the smallest
2041 // possible base offset.
2042 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
2043 const bool off_beyond_header = (off >= min_base_off);
2044
2045 // Try to constant-fold a stable array element.
2046 if (FoldStableValues && !is_mismatched_access() && ary->is_stable()) {
2047 // Make sure the reference is not into the header and the offset is constant
2048 ciObject* aobj = ary->const_oop();
2049 if (aobj != nullptr && off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) {
2050 int stable_dimension = (ary->stable_dimension() > 0 ? ary->stable_dimension() - 1 : 0);
2051 const Type* con_type = Type::make_constant_from_array_element(aobj->as_array(), off,
2052 stable_dimension,
2053 value_basic_type(), is_unsigned());
2054 if (con_type != nullptr) {
2055 return con_type;
2056 }
2057 }
2058 }
2059
2060 // Don't do this for integer types. There is only potential profit if
2061 // the element type t is lower than _type; that is, for int types, if _type is
2062 // more restrictive than t. This only happens here if one is short and the other
2063 // char (both 16 bits), and in those cases we've made an intentional decision
2064 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
2065 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
2066 //
2067 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
2068 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
2069 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
2070 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
2071 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
2072 // In fact, that could have been the original type of p1, and p1 could have
2073 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
2074 // expression (LShiftL quux 3) independently optimized to the constant 8.
2075 if ((t->isa_int() == nullptr) && (t->isa_long() == nullptr)
2076 && (_type->isa_vect() == nullptr)
2077 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
2078 // t might actually be lower than _type, if _type is a unique
2079 // concrete subclass of abstract class t.
2080 if (off_beyond_header || off == Type::OffsetBot) { // is the offset beyond the header?
2081 const Type* jt = t->join_speculative(_type);
2082 // In any case, do not allow the join, per se, to empty out the type.
2083 if (jt->empty() && !t->empty()) {
2084 // This can happen if a interface-typed array narrows to a class type.
2085 jt = _type;
2086 }
2087 #ifdef ASSERT
2088 if (phase->C->eliminate_boxing() && adr->is_AddP()) {
2089 // The pointers in the autobox arrays are always non-null
2090 Node* base = adr->in(AddPNode::Base);
2091 if ((base != nullptr) && base->is_DecodeN()) {
2092 // Get LoadN node which loads IntegerCache.cache field
2093 base = base->in(1);
2094 }
2095 if ((base != nullptr) && base->is_Con()) {
2096 const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr();
2097 if ((base_type != nullptr) && base_type->is_autobox_cache()) {
2098 // It could be narrow oop
2099 assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity");
2100 }
2101 }
2102 }
2103 #endif
2104 return jt;
2105 }
2106 }
2107 } else if (tp->base() == Type::InstPtr) {
2108 assert( off != Type::OffsetBot ||
2109 // arrays can be cast to Objects
2110 !tp->isa_instptr() ||
2111 tp->is_instptr()->instance_klass()->is_java_lang_Object() ||
2112 // unsafe field access may not have a constant offset
2113 C->has_unsafe_access(),
2114 "Field accesses must be precise" );
2115 // For oop loads, we expect the _type to be precise.
2116
2117 // Optimize loads from constant fields.
2118 const TypeInstPtr* tinst = tp->is_instptr();
2119 ciObject* const_oop = tinst->const_oop();
2120 if (!is_mismatched_access() && off != Type::OffsetBot && const_oop != nullptr && const_oop->is_instance()) {
2121 const Type* con_type = Type::make_constant_from_field(const_oop->as_instance(), off, is_unsigned(), value_basic_type());
2122 if (con_type != nullptr) {
2123 return con_type;
2124 }
2125 }
2126 } else if (tp->base() == Type::KlassPtr || tp->base() == Type::InstKlassPtr || tp->base() == Type::AryKlassPtr) {
2127 assert(off != Type::OffsetBot ||
2128 !tp->isa_instklassptr() ||
2129 // arrays can be cast to Objects
2130 tp->isa_instklassptr()->instance_klass()->is_java_lang_Object() ||
2131 // also allow array-loading from the primary supertype
2132 // array during subtype checks
2133 Opcode() == Op_LoadKlass,
2134 "Field accesses must be precise");
2135 // For klass/static loads, we expect the _type to be precise
2136 } else if (tp->base() == Type::RawPtr && adr->is_Load() && off == 0) {
2137 /* With mirrors being an indirect in the Klass*
2138 * the VM is now using two loads. LoadKlass(LoadP(LoadP(Klass, mirror_offset), zero_offset))
2139 * The LoadP from the Klass has a RawPtr type (see LibraryCallKit::load_mirror_from_klass).
2140 *
2141 * So check the type and klass of the node before the LoadP.
2142 */
2143 Node* adr2 = adr->in(MemNode::Address);
2144 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2145 if (tkls != nullptr && !StressReflectiveCode) {
2146 if (tkls->is_loaded() && tkls->klass_is_exact() && tkls->offset() == in_bytes(Klass::java_mirror_offset())) {
2147 ciKlass* klass = tkls->exact_klass();
2148 assert(adr->Opcode() == Op_LoadP, "must load an oop from _java_mirror");
2149 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
2150 return TypeInstPtr::make(klass->java_mirror());
2151 }
2152 }
2153 }
2154
2155 const TypeKlassPtr *tkls = tp->isa_klassptr();
2156 if (tkls != nullptr) {
2157 if (tkls->is_loaded() && tkls->klass_is_exact()) {
2158 ciKlass* klass = tkls->exact_klass();
2159 // We are loading a field from a Klass metaobject whose identity
2160 // is known at compile time (the type is "exact" or "precise").
2161 // Check for fields we know are maintained as constants by the VM.
2162 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) {
2163 // The field is Klass::_super_check_offset. Return its (constant) value.
2164 // (Folds up type checking code.)
2165 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
2166 return TypeInt::make(klass->super_check_offset());
2167 }
2168 // Class encoding in prototype header may change between runs.
2169 // Force loading prototype header when AOT code is generated.
2170 if (UseCompactObjectHeaders && !AOTCodeCache::is_on_for_dump()) {
2171 if (tkls->offset() == in_bytes(Klass::prototype_header_offset())) {
2172 // The field is Klass::_prototype_header. Return its (constant) value.
2173 assert(this->Opcode() == Op_LoadX, "must load a proper type from _prototype_header");
2174 return TypeX::make(klass->prototype_header());
2175 }
2176 }
2177 // Compute index into primary_supers array
2178 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
2179 // Check for overflowing; use unsigned compare to handle the negative case.
2180 if( depth < ciKlass::primary_super_limit() ) {
2181 // The field is an element of Klass::_primary_supers. Return its (constant) value.
2182 // (Folds up type checking code.)
2183 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
2184 ciKlass *ss = klass->super_of_depth(depth);
2185 return ss ? TypeKlassPtr::make(ss, Type::trust_interfaces) : TypePtr::NULL_PTR;
2186 }
2187 const Type* aift = load_array_final_field(tkls, klass);
2188 if (aift != nullptr) return aift;
2189 }
2190
2191 // We can still check if we are loading from the primary_supers array at a
2192 // shallow enough depth. Even though the klass is not exact, entries less
2193 // than or equal to its super depth are correct.
2194 if (tkls->is_loaded()) {
2195 ciKlass* klass = nullptr;
2196 if (tkls->isa_instklassptr()) {
2197 klass = tkls->is_instklassptr()->instance_klass();
2198 } else {
2199 int dims;
2200 const Type* inner = tkls->is_aryklassptr()->base_element_type(dims);
2201 if (inner->isa_instklassptr()) {
2202 klass = inner->is_instklassptr()->instance_klass();
2203 klass = ciObjArrayKlass::make(klass, dims);
2204 }
2205 }
2206 if (klass != nullptr) {
2207 // Compute index into primary_supers array
2208 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
2209 // Check for overflowing; use unsigned compare to handle the negative case.
2210 if (depth < ciKlass::primary_super_limit() &&
2211 depth <= klass->super_depth()) { // allow self-depth checks to handle self-check case
2212 // The field is an element of Klass::_primary_supers. Return its (constant) value.
2213 // (Folds up type checking code.)
2214 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
2215 ciKlass *ss = klass->super_of_depth(depth);
2216 return ss ? TypeKlassPtr::make(ss, Type::trust_interfaces) : TypePtr::NULL_PTR;
2217 }
2218 }
2219 }
2220
2221 // If the type is enough to determine that the thing is not an array,
2222 // we can give the layout_helper a positive interval type.
2223 // This will help short-circuit some reflective code.
2224 if (tkls->offset() == in_bytes(Klass::layout_helper_offset()) &&
2225 tkls->isa_instklassptr() && // not directly typed as an array
2226 !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
2227 ) {
2228 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
2229 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
2230 // The key property of this type is that it folds up tests
2231 // for array-ness, since it proves that the layout_helper is positive.
2232 // Thus, a generic value like the basic object layout helper works fine.
2233 return TypeInt::make(min_size, max_jint, Type::WidenMin);
2234 }
2235 }
2236
2237 bool is_vect = (_type->isa_vect() != nullptr);
2238 if (is_instance && !is_vect) {
2239 // If we have an instance type and our memory input is the
2240 // programs's initial memory state, there is no matching store,
2241 // so just return a zero of the appropriate type -
2242 // except if it is vectorized - then we have no zero constant.
2243 Node *mem = in(MemNode::Memory);
2244 if (mem->is_Parm() && mem->in(0)->is_Start()) {
2245 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
2246 return Type::get_zero_type(_type->basic_type());
2247 }
2248 }
2249
2250 if (!UseCompactObjectHeaders) {
2251 Node* alloc = is_new_object_mark_load();
2252 if (alloc != nullptr) {
2253 return TypeX::make(markWord::prototype().value());
2254 }
2255 }
2256
2257 return _type;
2258 }
2259
2260 //------------------------------match_edge-------------------------------------
2261 // Do we Match on this edge index or not? Match only the address.
2262 uint LoadNode::match_edge(uint idx) const {
2263 return idx == MemNode::Address;
2264 }
2265
2266 //--------------------------LoadBNode::Ideal--------------------------------------
2267 //
2268 // If the previous store is to the same address as this load,
2269 // and the value stored was larger than a byte, replace this load
2270 // with the value stored truncated to a byte. If no truncation is
2271 // needed, the replacement is done in LoadNode::Identity().
2272 //
2273 Node* LoadBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2274 Node* mem = in(MemNode::Memory);
2275 Node* value = can_see_stored_value(mem,phase);
2276 if (value != nullptr) {
2277 Node* narrow = Compile::narrow_value(T_BYTE, value, _type, phase, false);
2278 if (narrow != value) {
2279 return narrow;
2280 }
2281 }
2282 // Identity call will handle the case where truncation is not needed.
2283 return LoadNode::Ideal(phase, can_reshape);
2284 }
2285
2286 const Type* LoadBNode::Value(PhaseGVN* phase) const {
2287 Node* mem = in(MemNode::Memory);
2288 Node* value = can_see_stored_value(mem,phase);
2289 if (value != nullptr && value->is_Con() &&
2290 !value->bottom_type()->higher_equal(_type)) {
2291 // If the input to the store does not fit with the load's result type,
2292 // it must be truncated. We can't delay until Ideal call since
2293 // a singleton Value is needed for split_thru_phi optimization.
2294 int con = value->get_int();
2295 return TypeInt::make((con << 24) >> 24);
2296 }
2297 return LoadNode::Value(phase);
2298 }
2299
2300 //--------------------------LoadUBNode::Ideal-------------------------------------
2301 //
2302 // If the previous store is to the same address as this load,
2303 // and the value stored was larger than a byte, replace this load
2304 // with the value stored truncated to a byte. If no truncation is
2305 // needed, the replacement is done in LoadNode::Identity().
2306 //
2307 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2308 Node* mem = in(MemNode::Memory);
2309 Node* value = can_see_stored_value(mem, phase);
2310 if (value != nullptr) {
2311 Node* narrow = Compile::narrow_value(T_BOOLEAN, value, _type, phase, false);
2312 if (narrow != value) {
2313 return narrow;
2314 }
2315 }
2316 // Identity call will handle the case where truncation is not needed.
2317 return LoadNode::Ideal(phase, can_reshape);
2318 }
2319
2320 const Type* LoadUBNode::Value(PhaseGVN* phase) const {
2321 Node* mem = in(MemNode::Memory);
2322 Node* value = can_see_stored_value(mem,phase);
2323 if (value != nullptr && value->is_Con() &&
2324 !value->bottom_type()->higher_equal(_type)) {
2325 // If the input to the store does not fit with the load's result type,
2326 // it must be truncated. We can't delay until Ideal call since
2327 // a singleton Value is needed for split_thru_phi optimization.
2328 int con = value->get_int();
2329 return TypeInt::make(con & 0xFF);
2330 }
2331 return LoadNode::Value(phase);
2332 }
2333
2334 //--------------------------LoadUSNode::Ideal-------------------------------------
2335 //
2336 // If the previous store is to the same address as this load,
2337 // and the value stored was larger than a char, replace this load
2338 // with the value stored truncated to a char. If no truncation is
2339 // needed, the replacement is done in LoadNode::Identity().
2340 //
2341 Node* LoadUSNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2342 Node* mem = in(MemNode::Memory);
2343 Node* value = can_see_stored_value(mem,phase);
2344 if (value != nullptr) {
2345 Node* narrow = Compile::narrow_value(T_CHAR, value, _type, phase, false);
2346 if (narrow != value) {
2347 return narrow;
2348 }
2349 }
2350 // Identity call will handle the case where truncation is not needed.
2351 return LoadNode::Ideal(phase, can_reshape);
2352 }
2353
2354 const Type* LoadUSNode::Value(PhaseGVN* phase) const {
2355 Node* mem = in(MemNode::Memory);
2356 Node* value = can_see_stored_value(mem,phase);
2357 if (value != nullptr && value->is_Con() &&
2358 !value->bottom_type()->higher_equal(_type)) {
2359 // If the input to the store does not fit with the load's result type,
2360 // it must be truncated. We can't delay until Ideal call since
2361 // a singleton Value is needed for split_thru_phi optimization.
2362 int con = value->get_int();
2363 return TypeInt::make(con & 0xFFFF);
2364 }
2365 return LoadNode::Value(phase);
2366 }
2367
2368 //--------------------------LoadSNode::Ideal--------------------------------------
2369 //
2370 // If the previous store is to the same address as this load,
2371 // and the value stored was larger than a short, replace this load
2372 // with the value stored truncated to a short. If no truncation is
2373 // needed, the replacement is done in LoadNode::Identity().
2374 //
2375 Node* LoadSNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2376 Node* mem = in(MemNode::Memory);
2377 Node* value = can_see_stored_value(mem,phase);
2378 if (value != nullptr) {
2379 Node* narrow = Compile::narrow_value(T_SHORT, value, _type, phase, false);
2380 if (narrow != value) {
2381 return narrow;
2382 }
2383 }
2384 // Identity call will handle the case where truncation is not needed.
2385 return LoadNode::Ideal(phase, can_reshape);
2386 }
2387
2388 const Type* LoadSNode::Value(PhaseGVN* phase) const {
2389 Node* mem = in(MemNode::Memory);
2390 Node* value = can_see_stored_value(mem,phase);
2391 if (value != nullptr && value->is_Con() &&
2392 !value->bottom_type()->higher_equal(_type)) {
2393 // If the input to the store does not fit with the load's result type,
2394 // it must be truncated. We can't delay until Ideal call since
2395 // a singleton Value is needed for split_thru_phi optimization.
2396 int con = value->get_int();
2397 return TypeInt::make((con << 16) >> 16);
2398 }
2399 return LoadNode::Value(phase);
2400 }
2401
2402 //=============================================================================
2403 //----------------------------LoadKlassNode::make------------------------------
2404 // Polymorphic factory method:
2405 Node* LoadKlassNode::make(PhaseGVN& gvn, Node* mem, Node* adr, const TypePtr* at, const TypeKlassPtr* tk) {
2406 // sanity check the alias category against the created node type
2407 const TypePtr* adr_type = adr->bottom_type()->isa_ptr();
2408 assert(adr_type != nullptr, "expecting TypeKlassPtr");
2409 #ifdef _LP64
2410 if (adr_type->is_ptr_to_narrowklass()) {
2411 assert(UseCompressedClassPointers, "no compressed klasses");
2412 Node* load_klass = gvn.transform(new LoadNKlassNode(mem, adr, at, tk->make_narrowklass(), MemNode::unordered));
2413 return new DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr());
2414 }
2415 #endif
2416 assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
2417 return new LoadKlassNode(mem, adr, at, tk, MemNode::unordered);
2418 }
2419
2420 //------------------------------Value------------------------------------------
2421 const Type* LoadKlassNode::Value(PhaseGVN* phase) const {
2422 return klass_value_common(phase);
2423 }
2424
2425 const Type* LoadNode::klass_value_common(PhaseGVN* phase) const {
2426 // Either input is TOP ==> the result is TOP
2427 const Type *t1 = phase->type( in(MemNode::Memory) );
2428 if (t1 == Type::TOP) return Type::TOP;
2429 Node *adr = in(MemNode::Address);
2430 const Type *t2 = phase->type( adr );
2431 if (t2 == Type::TOP) return Type::TOP;
2432 const TypePtr *tp = t2->is_ptr();
2433 if (TypePtr::above_centerline(tp->ptr()) ||
2434 tp->ptr() == TypePtr::Null) return Type::TOP;
2435
2436 // Return a more precise klass, if possible
2437 const TypeInstPtr *tinst = tp->isa_instptr();
2438 if (tinst != nullptr) {
2439 ciInstanceKlass* ik = tinst->instance_klass();
2440 int offset = tinst->offset();
2441 if (ik == phase->C->env()->Class_klass()
2442 && (offset == java_lang_Class::klass_offset() ||
2443 offset == java_lang_Class::array_klass_offset())) {
2444 // We are loading a special hidden field from a Class mirror object,
2445 // the field which points to the VM's Klass metaobject.
2446 ciType* t = tinst->java_mirror_type();
2447 // java_mirror_type returns non-null for compile-time Class constants.
2448 if (t != nullptr) {
2449 // constant oop => constant klass
2450 if (offset == java_lang_Class::array_klass_offset()) {
2451 if (t->is_void()) {
2452 // We cannot create a void array. Since void is a primitive type return null
2453 // klass. Users of this result need to do a null check on the returned klass.
2454 return TypePtr::NULL_PTR;
2455 }
2456 return TypeKlassPtr::make(ciArrayKlass::make(t), Type::trust_interfaces);
2457 }
2458 if (!t->is_klass()) {
2459 // a primitive Class (e.g., int.class) has null for a klass field
2460 return TypePtr::NULL_PTR;
2461 }
2462 // Fold up the load of the hidden field
2463 return TypeKlassPtr::make(t->as_klass(), Type::trust_interfaces);
2464 }
2465 // non-constant mirror, so we can't tell what's going on
2466 }
2467 if (!tinst->is_loaded())
2468 return _type; // Bail out if not loaded
2469 if (offset == oopDesc::klass_offset_in_bytes()) {
2470 return tinst->as_klass_type(true);
2471 }
2472 }
2473
2474 // Check for loading klass from an array
2475 const TypeAryPtr *tary = tp->isa_aryptr();
2476 if (tary != nullptr &&
2477 tary->offset() == oopDesc::klass_offset_in_bytes()) {
2478 return tary->as_klass_type(true);
2479 }
2480
2481 // Check for loading klass from an array klass
2482 const TypeKlassPtr *tkls = tp->isa_klassptr();
2483 if (tkls != nullptr && !StressReflectiveCode) {
2484 if (!tkls->is_loaded())
2485 return _type; // Bail out if not loaded
2486 if (tkls->isa_aryklassptr() && tkls->is_aryklassptr()->elem()->isa_klassptr() &&
2487 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) {
2488 // // Always returning precise element type is incorrect,
2489 // // e.g., element type could be object and array may contain strings
2490 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
2491
2492 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
2493 // according to the element type's subclassing.
2494 return tkls->is_aryklassptr()->elem()->isa_klassptr()->cast_to_exactness(tkls->klass_is_exact());
2495 }
2496 if (tkls->isa_instklassptr() != nullptr && tkls->klass_is_exact() &&
2497 tkls->offset() == in_bytes(Klass::super_offset())) {
2498 ciKlass* sup = tkls->is_instklassptr()->instance_klass()->super();
2499 // The field is Klass::_super. Return its (constant) value.
2500 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
2501 return sup ? TypeKlassPtr::make(sup, Type::trust_interfaces) : TypePtr::NULL_PTR;
2502 }
2503 }
2504
2505 if (tkls != nullptr && !UseSecondarySupersCache
2506 && tkls->offset() == in_bytes(Klass::secondary_super_cache_offset())) {
2507 // Treat Klass::_secondary_super_cache as a constant when the cache is disabled.
2508 return TypePtr::NULL_PTR;
2509 }
2510
2511 // Bailout case
2512 return LoadNode::Value(phase);
2513 }
2514
2515 //------------------------------Identity---------------------------------------
2516 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
2517 // Also feed through the klass in Allocate(...klass...)._klass.
2518 Node* LoadKlassNode::Identity(PhaseGVN* phase) {
2519 return klass_identity_common(phase);
2520 }
2521
2522 Node* LoadNode::klass_identity_common(PhaseGVN* phase) {
2523 Node* x = LoadNode::Identity(phase);
2524 if (x != this) return x;
2525
2526 // Take apart the address into an oop and offset.
2527 // Return 'this' if we cannot.
2528 Node* adr = in(MemNode::Address);
2529 intptr_t offset = 0;
2530 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2531 if (base == nullptr) return this;
2532 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
2533 if (toop == nullptr) return this;
2534
2535 // Step over potential GC barrier for OopHandle resolve
2536 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
2537 if (bs->is_gc_barrier_node(base)) {
2538 base = bs->step_over_gc_barrier(base);
2539 }
2540
2541 // We can fetch the klass directly through an AllocateNode.
2542 // This works even if the klass is not constant (clone or newArray).
2543 if (offset == oopDesc::klass_offset_in_bytes()) {
2544 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
2545 if (allocated_klass != nullptr) {
2546 return allocated_klass;
2547 }
2548 }
2549
2550 // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*.
2551 // See inline_native_Class_query for occurrences of these patterns.
2552 // Java Example: x.getClass().isAssignableFrom(y)
2553 //
2554 // This improves reflective code, often making the Class
2555 // mirror go completely dead. (Current exception: Class
2556 // mirrors may appear in debug info, but we could clean them out by
2557 // introducing a new debug info operator for Klass.java_mirror).
2558
2559 if (toop->isa_instptr() && toop->is_instptr()->instance_klass() == phase->C->env()->Class_klass()
2560 && offset == java_lang_Class::klass_offset()) {
2561 if (base->is_Load()) {
2562 Node* base2 = base->in(MemNode::Address);
2563 if (base2->is_Load()) { /* direct load of a load which is the OopHandle */
2564 Node* adr2 = base2->in(MemNode::Address);
2565 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2566 if (tkls != nullptr && !tkls->empty()
2567 && (tkls->isa_instklassptr() || tkls->isa_aryklassptr())
2568 && adr2->is_AddP()
2569 ) {
2570 int mirror_field = in_bytes(Klass::java_mirror_offset());
2571 if (tkls->offset() == mirror_field) {
2572 return adr2->in(AddPNode::Base);
2573 }
2574 }
2575 }
2576 }
2577 }
2578
2579 return this;
2580 }
2581
2582 LoadNode* LoadNode::clone_pinned() const {
2583 LoadNode* ld = clone()->as_Load();
2584 ld->_control_dependency = UnknownControl;
2585 return ld;
2586 }
2587
2588
2589 //------------------------------Value------------------------------------------
2590 const Type* LoadNKlassNode::Value(PhaseGVN* phase) const {
2591 const Type *t = klass_value_common(phase);
2592 if (t == Type::TOP)
2593 return t;
2594
2595 return t->make_narrowklass();
2596 }
2597
2598 //------------------------------Identity---------------------------------------
2599 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
2600 // Also feed through the klass in Allocate(...klass...)._klass.
2601 Node* LoadNKlassNode::Identity(PhaseGVN* phase) {
2602 Node *x = klass_identity_common(phase);
2603
2604 const Type *t = phase->type( x );
2605 if( t == Type::TOP ) return x;
2606 if( t->isa_narrowklass()) return x;
2607 assert (!t->isa_narrowoop(), "no narrow oop here");
2608
2609 return phase->transform(new EncodePKlassNode(x, t->make_narrowklass()));
2610 }
2611
2612 //------------------------------Value-----------------------------------------
2613 const Type* LoadRangeNode::Value(PhaseGVN* phase) const {
2614 // Either input is TOP ==> the result is TOP
2615 const Type *t1 = phase->type( in(MemNode::Memory) );
2616 if( t1 == Type::TOP ) return Type::TOP;
2617 Node *adr = in(MemNode::Address);
2618 const Type *t2 = phase->type( adr );
2619 if( t2 == Type::TOP ) return Type::TOP;
2620 const TypePtr *tp = t2->is_ptr();
2621 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
2622 const TypeAryPtr *tap = tp->isa_aryptr();
2623 if( !tap ) return _type;
2624 return tap->size();
2625 }
2626
2627 //-------------------------------Ideal---------------------------------------
2628 // Feed through the length in AllocateArray(...length...)._length.
2629 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2630 Node* p = MemNode::Ideal_common(phase, can_reshape);
2631 if (p) return (p == NodeSentinel) ? nullptr : p;
2632
2633 // Take apart the address into an oop and offset.
2634 // Return 'this' if we cannot.
2635 Node* adr = in(MemNode::Address);
2636 intptr_t offset = 0;
2637 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2638 if (base == nullptr) return nullptr;
2639 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2640 if (tary == nullptr) return nullptr;
2641
2642 // We can fetch the length directly through an AllocateArrayNode.
2643 // This works even if the length is not constant (clone or newArray).
2644 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2645 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base);
2646 if (alloc != nullptr) {
2647 Node* allocated_length = alloc->Ideal_length();
2648 Node* len = alloc->make_ideal_length(tary, phase);
2649 if (allocated_length != len) {
2650 // New CastII improves on this.
2651 return len;
2652 }
2653 }
2654 }
2655
2656 return nullptr;
2657 }
2658
2659 //------------------------------Identity---------------------------------------
2660 // Feed through the length in AllocateArray(...length...)._length.
2661 Node* LoadRangeNode::Identity(PhaseGVN* phase) {
2662 Node* x = LoadINode::Identity(phase);
2663 if (x != this) return x;
2664
2665 // Take apart the address into an oop and offset.
2666 // Return 'this' if we cannot.
2667 Node* adr = in(MemNode::Address);
2668 intptr_t offset = 0;
2669 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2670 if (base == nullptr) return this;
2671 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2672 if (tary == nullptr) return this;
2673
2674 // We can fetch the length directly through an AllocateArrayNode.
2675 // This works even if the length is not constant (clone or newArray).
2676 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2677 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base);
2678 if (alloc != nullptr) {
2679 Node* allocated_length = alloc->Ideal_length();
2680 // Do not allow make_ideal_length to allocate a CastII node.
2681 Node* len = alloc->make_ideal_length(tary, phase, false);
2682 if (allocated_length == len) {
2683 // Return allocated_length only if it would not be improved by a CastII.
2684 return allocated_length;
2685 }
2686 }
2687 }
2688
2689 return this;
2690
2691 }
2692
2693 //=============================================================================
2694 //---------------------------StoreNode::make-----------------------------------
2695 // Polymorphic factory method:
2696 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) {
2697 assert((mo == unordered || mo == release), "unexpected");
2698 Compile* C = gvn.C;
2699 assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2700 ctl != nullptr, "raw memory operations should have control edge");
2701
2702 switch (bt) {
2703 case T_BOOLEAN: val = gvn.transform(new AndINode(val, gvn.intcon(0x1))); // Fall through to T_BYTE case
2704 case T_BYTE: return new StoreBNode(ctl, mem, adr, adr_type, val, mo);
2705 case T_INT: return new StoreINode(ctl, mem, adr, adr_type, val, mo);
2706 case T_CHAR:
2707 case T_SHORT: return new StoreCNode(ctl, mem, adr, adr_type, val, mo);
2708 case T_LONG: return new StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic_access);
2709 case T_FLOAT: return new StoreFNode(ctl, mem, adr, adr_type, val, mo);
2710 case T_DOUBLE: return new StoreDNode(ctl, mem, adr, adr_type, val, mo, require_atomic_access);
2711 case T_METADATA:
2712 case T_ADDRESS:
2713 case T_OBJECT:
2714 #ifdef _LP64
2715 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
2716 val = gvn.transform(new EncodePNode(val, val->bottom_type()->make_narrowoop()));
2717 return new StoreNNode(ctl, mem, adr, adr_type, val, mo);
2718 } else if (adr->bottom_type()->is_ptr_to_narrowklass() ||
2719 (UseCompressedClassPointers && val->bottom_type()->isa_klassptr() &&
2720 adr->bottom_type()->isa_rawptr())) {
2721 val = gvn.transform(new EncodePKlassNode(val, val->bottom_type()->make_narrowklass()));
2722 return new StoreNKlassNode(ctl, mem, adr, adr_type, val, mo);
2723 }
2724 #endif
2725 {
2726 return new StorePNode(ctl, mem, adr, adr_type, val, mo);
2727 }
2728 default:
2729 ShouldNotReachHere();
2730 return (StoreNode*)nullptr;
2731 }
2732 }
2733
2734 //--------------------------bottom_type----------------------------------------
2735 const Type *StoreNode::bottom_type() const {
2736 return Type::MEMORY;
2737 }
2738
2739 //------------------------------hash-------------------------------------------
2740 uint StoreNode::hash() const {
2741 // unroll addition of interesting fields
2742 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2743
2744 // Since they are not commoned, do not hash them:
2745 return NO_HASH;
2746 }
2747
2748 // Link together multiple stores (B/S/C/I) into a longer one.
2749 //
2750 // Example: _store = StoreB[i+3]
2751 //
2752 // RangeCheck[i+0] RangeCheck[i+0]
2753 // StoreB[i+0]
2754 // RangeCheck[i+3] RangeCheck[i+3]
2755 // StoreB[i+1] --> pass: fail:
2756 // StoreB[i+2] StoreI[i+0] StoreB[i+0]
2757 // StoreB[i+3]
2758 //
2759 // The 4 StoreB are merged into a single StoreI node. We have to be careful with RangeCheck[i+1]: before
2760 // the optimization, if this RangeCheck[i+1] fails, then we execute only StoreB[i+0], and then trap. After
2761 // the optimization, the new StoreI[i+0] is on the passing path of RangeCheck[i+3], and StoreB[i+0] on the
2762 // failing path.
2763 //
2764 // Note: For normal array stores, every store at first has a RangeCheck. But they can be removed with:
2765 // - RCE (RangeCheck Elimination): the RangeChecks in the loop are hoisted out and before the loop,
2766 // and possibly no RangeChecks remain between the stores.
2767 // - RangeCheck smearing: the earlier RangeChecks are adjusted such that they cover later RangeChecks,
2768 // and those later RangeChecks can be removed. Example:
2769 //
2770 // RangeCheck[i+0] RangeCheck[i+0] <- before first store
2771 // StoreB[i+0] StoreB[i+0] <- first store
2772 // RangeCheck[i+1] --> smeared --> RangeCheck[i+3] <- only RC between first and last store
2773 // StoreB[i+1] StoreB[i+1] <- second store
2774 // RangeCheck[i+2] --> removed
2775 // StoreB[i+2] StoreB[i+2]
2776 // RangeCheck[i+3] --> removed
2777 // StoreB[i+3] StoreB[i+3] <- last store
2778 //
2779 // Thus, it is a common pattern that between the first and last store in a chain
2780 // of adjacent stores there remains exactly one RangeCheck, located between the
2781 // first and the second store (e.g. RangeCheck[i+3]).
2782 //
2783 class MergePrimitiveStores : public StackObj {
2784 private:
2785 PhaseGVN* const _phase;
2786 StoreNode* const _store;
2787 // State machine with initial state Unknown
2788 // Allowed transitions:
2789 // Unknown -> Const
2790 // Unknown -> Platform
2791 // Unknown -> Reverse
2792 // Unknown -> NotAdjacent
2793 // Const -> Const
2794 // Const -> NotAdjacent
2795 // Platform -> Platform
2796 // Platform -> NotAdjacent
2797 // Reverse -> Reverse
2798 // Reverse -> NotAdjacent
2799 // NotAdjacent -> NotAdjacent
2800 enum ValueOrder : uint8_t {
2801 Unknown, // Initial state
2802 Const, // Input values are const
2803 Platform, // Platform order
2804 Reverse, // Reverse platform order
2805 NotAdjacent // Not adjacent
2806 };
2807 ValueOrder _value_order;
2808
2809 NOT_PRODUCT( const CHeapBitMap &_trace_tags; )
2810
2811 public:
2812 MergePrimitiveStores(PhaseGVN* phase, StoreNode* store) :
2813 _phase(phase), _store(store), _value_order(ValueOrder::Unknown)
2814 NOT_PRODUCT( COMMA _trace_tags(Compile::current()->directive()->trace_merge_stores_tags()) )
2815 {}
2816
2817 StoreNode* run();
2818
2819 private:
2820 bool is_compatible_store(const StoreNode* other_store) const;
2821 bool is_adjacent_pair(const StoreNode* use_store, const StoreNode* def_store) const;
2822 bool is_adjacent_input_pair(const Node* n1, const Node* n2, const int memory_size) const;
2823 static bool is_con_RShift(const Node* n, Node const*& base_out, jint& shift_out, PhaseGVN* phase);
2824 enum CFGStatus { SuccessNoRangeCheck, SuccessWithRangeCheck, Failure };
2825 static CFGStatus cfg_status_for_pair(const StoreNode* use_store, const StoreNode* def_store);
2826
2827 class Status {
2828 private:
2829 StoreNode* _found_store;
2830 bool _found_range_check;
2831
2832 Status(StoreNode* found_store, bool found_range_check)
2833 : _found_store(found_store), _found_range_check(found_range_check) {}
2834
2835 public:
2836 StoreNode* found_store() const { return _found_store; }
2837 bool found_range_check() const { return _found_range_check; }
2838 static Status make_failure() { return Status(nullptr, false); }
2839
2840 static Status make(StoreNode* found_store, const CFGStatus cfg_status) {
2841 if (cfg_status == CFGStatus::Failure) {
2842 return Status::make_failure();
2843 }
2844 return Status(found_store, cfg_status == CFGStatus::SuccessWithRangeCheck);
2845 }
2846
2847 #ifndef PRODUCT
2848 void print_on(outputStream* st) const {
2849 if (_found_store == nullptr) {
2850 st->print_cr("None");
2851 } else {
2852 st->print_cr("Found[%d %s, %s]", _found_store->_idx, _found_store->Name(),
2853 _found_range_check ? "RC" : "no-RC");
2854 }
2855 }
2856 #endif
2857 };
2858
2859 enum ValueOrder find_adjacent_input_value_order(const Node* n1, const Node* n2, const int memory_size) const;
2860 Status find_adjacent_use_store(const StoreNode* def_store) const;
2861 Status find_adjacent_def_store(const StoreNode* use_store) const;
2862 Status find_use_store(const StoreNode* def_store) const;
2863 Status find_def_store(const StoreNode* use_store) const;
2864 Status find_use_store_unidirectional(const StoreNode* def_store) const;
2865 Status find_def_store_unidirectional(const StoreNode* use_store) const;
2866
2867 void collect_merge_list(Node_List& merge_list) const;
2868 Node* make_merged_input_value(const Node_List& merge_list);
2869 StoreNode* make_merged_store(const Node_List& merge_list, Node* merged_input_value);
2870
2871 #ifndef PRODUCT
2872 // Access to TraceMergeStores tags
2873 bool is_trace(TraceMergeStores::Tag tag) const {
2874 return _trace_tags.at(tag);
2875 }
2876
2877 bool is_trace_basic() const {
2878 return is_trace(TraceMergeStores::Tag::BASIC);
2879 }
2880
2881 bool is_trace_pointer_parsing() const {
2882 return is_trace(TraceMergeStores::Tag::POINTER_PARSING);
2883 }
2884
2885 bool is_trace_pointer_aliasing() const {
2886 return is_trace(TraceMergeStores::Tag::POINTER_ALIASING);
2887 }
2888
2889 bool is_trace_pointer_adjacency() const {
2890 return is_trace(TraceMergeStores::Tag::POINTER_ADJACENCY);
2891 }
2892
2893 bool is_trace_success() const {
2894 return is_trace(TraceMergeStores::Tag::SUCCESS);
2895 }
2896 #endif
2897
2898 NOT_PRODUCT( void trace(const Node_List& merge_list, const Node* merged_input_value, const StoreNode* merged_store) const; )
2899 };
2900
2901 StoreNode* MergePrimitiveStores::run() {
2902 // Check for B/S/C/I
2903 int opc = _store->Opcode();
2904 if (opc != Op_StoreB && opc != Op_StoreC && opc != Op_StoreI) {
2905 return nullptr;
2906 }
2907
2908 NOT_PRODUCT( if (is_trace_basic()) { tty->print("[TraceMergeStores] MergePrimitiveStores::run: "); _store->dump(); })
2909
2910 // The _store must be the "last" store in a chain. If we find a use we could merge with
2911 // then that use or a store further down is the "last" store.
2912 Status status_use = find_adjacent_use_store(_store);
2913 NOT_PRODUCT( if (is_trace_basic()) { tty->print("[TraceMergeStores] expect no use: "); status_use.print_on(tty); })
2914 if (status_use.found_store() != nullptr) {
2915 return nullptr;
2916 }
2917
2918 // Check if we can merge with at least one def, so that we have at least 2 stores to merge.
2919 Status status_def = find_adjacent_def_store(_store);
2920 NOT_PRODUCT( if (is_trace_basic()) { tty->print("[TraceMergeStores] expect def: "); status_def.print_on(tty); })
2921 Node* def_store = status_def.found_store();
2922 if (def_store == nullptr) {
2923 return nullptr;
2924 }
2925
2926 // Initialize value order
2927 _value_order = find_adjacent_input_value_order(def_store->in(MemNode::ValueIn),
2928 _store->in(MemNode::ValueIn),
2929 _store->memory_size());
2930 assert(_value_order != ValueOrder::NotAdjacent && _value_order != ValueOrder::Unknown, "Order should be checked");
2931
2932 ResourceMark rm;
2933 Node_List merge_list;
2934 collect_merge_list(merge_list);
2935
2936 Node* merged_input_value = make_merged_input_value(merge_list);
2937 if (merged_input_value == nullptr) { return nullptr; }
2938
2939 StoreNode* merged_store = make_merged_store(merge_list, merged_input_value);
2940
2941 NOT_PRODUCT( if (is_trace_success()) { trace(merge_list, merged_input_value, merged_store); } )
2942
2943 return merged_store;
2944 }
2945
2946 // Check compatibility between _store and other_store.
2947 bool MergePrimitiveStores::is_compatible_store(const StoreNode* other_store) const {
2948 int opc = _store->Opcode();
2949 assert(opc == Op_StoreB || opc == Op_StoreC || opc == Op_StoreI, "precondition");
2950
2951 if (other_store == nullptr ||
2952 _store->Opcode() != other_store->Opcode()) {
2953 return false;
2954 }
2955
2956 return true;
2957 }
2958
2959 bool MergePrimitiveStores::is_adjacent_pair(const StoreNode* use_store, const StoreNode* def_store) const {
2960 if (!is_adjacent_input_pair(def_store->in(MemNode::ValueIn),
2961 use_store->in(MemNode::ValueIn),
2962 def_store->memory_size())) {
2963 return false;
2964 }
2965
2966 ResourceMark rm;
2967 #ifndef PRODUCT
2968 const TraceMemPointer trace(is_trace_pointer_parsing(),
2969 is_trace_pointer_aliasing(),
2970 is_trace_pointer_adjacency(),
2971 true);
2972 #endif
2973 const MemPointer pointer_use(use_store NOT_PRODUCT(COMMA trace));
2974 const MemPointer pointer_def(def_store NOT_PRODUCT(COMMA trace));
2975 return pointer_def.is_adjacent_to_and_before(pointer_use);
2976 }
2977
2978 // Check input values n1 and n2 can be merged and return the value order
2979 MergePrimitiveStores::ValueOrder MergePrimitiveStores::find_adjacent_input_value_order(const Node* n1, const Node* n2,
2980 const int memory_size) const {
2981 // Pattern: [n1 = ConI, n2 = ConI]
2982 if (n1->Opcode() == Op_ConI && n2->Opcode() == Op_ConI) {
2983 return ValueOrder::Const;
2984 }
2985
2986 Node const *base_n2;
2987 jint shift_n2;
2988 if (!is_con_RShift(n2, base_n2, shift_n2, _phase)) {
2989 return ValueOrder::NotAdjacent;
2990 }
2991 Node const *base_n1;
2992 jint shift_n1;
2993 if (!is_con_RShift(n1, base_n1, shift_n1, _phase)) {
2994 return ValueOrder::NotAdjacent;
2995 }
2996
2997 int bits_per_store = memory_size * 8;
2998 if (base_n1 != base_n2 ||
2999 abs(shift_n1 - shift_n2) != bits_per_store ||
3000 shift_n1 % bits_per_store != 0) {
3001 // Values are not adjacent
3002 return ValueOrder::NotAdjacent;
3003 }
3004
3005 // Detect value order
3006 #ifdef VM_LITTLE_ENDIAN
3007 return shift_n1 < shift_n2 ? ValueOrder::Platform // Pattern: [n1 = base >> shift, n2 = base >> (shift + memory_size)]
3008 : ValueOrder::Reverse; // Pattern: [n1 = base >> (shift + memory_size), n2 = base >> shift]
3009 #else
3010 return shift_n1 > shift_n2 ? ValueOrder::Platform // Pattern: [n1 = base >> (shift + memory_size), n2 = base >> shift]
3011 : ValueOrder::Reverse; // Pattern: [n1 = base >> shift, n2 = base >> (shift + memory_size)]
3012 #endif
3013 }
3014
3015 bool MergePrimitiveStores::is_adjacent_input_pair(const Node* n1, const Node* n2, const int memory_size) const {
3016 ValueOrder input_value_order = find_adjacent_input_value_order(n1, n2, memory_size);
3017
3018 switch (input_value_order) {
3019 case ValueOrder::NotAdjacent:
3020 return false;
3021 case ValueOrder::Reverse:
3022 if (memory_size != 1 ||
3023 !Matcher::match_rule_supported(Op_ReverseBytesS) ||
3024 !Matcher::match_rule_supported(Op_ReverseBytesI) ||
3025 !Matcher::match_rule_supported(Op_ReverseBytesL)) {
3026 // ReverseBytes are not supported by platform
3027 return false;
3028 }
3029 // fall-through.
3030 case ValueOrder::Const:
3031 case ValueOrder::Platform:
3032 if (_value_order == ValueOrder::Unknown) {
3033 // Initial state is Unknown, and we find a valid input value order
3034 return true;
3035 }
3036 // The value order can not be changed
3037 return _value_order == input_value_order;
3038 case ValueOrder::Unknown:
3039 default:
3040 ShouldNotReachHere();
3041 }
3042 return false;
3043 }
3044
3045 // Detect pattern: n = base_out >> shift_out
3046 bool MergePrimitiveStores::is_con_RShift(const Node* n, Node const*& base_out, jint& shift_out, PhaseGVN* phase) {
3047 assert(n != nullptr, "precondition");
3048
3049 int opc = n->Opcode();
3050 if (opc == Op_ConvL2I) {
3051 n = n->in(1);
3052 opc = n->Opcode();
3053 }
3054
3055 if ((opc == Op_RShiftI ||
3056 opc == Op_RShiftL ||
3057 opc == Op_URShiftI ||
3058 opc == Op_URShiftL) &&
3059 n->in(2)->is_ConI()) {
3060 base_out = n->in(1);
3061 shift_out = n->in(2)->get_int();
3062 // The shift must be positive:
3063 return shift_out >= 0;
3064 }
3065
3066 if (phase->type(n)->isa_int() != nullptr ||
3067 phase->type(n)->isa_long() != nullptr) {
3068 // (base >> 0)
3069 base_out = n;
3070 shift_out = 0;
3071 return true;
3072 }
3073 return false;
3074 }
3075
3076 // Check if there is nothing between the two stores, except optionally a RangeCheck leading to an uncommon trap.
3077 MergePrimitiveStores::CFGStatus MergePrimitiveStores::cfg_status_for_pair(const StoreNode* use_store, const StoreNode* def_store) {
3078 assert(use_store->in(MemNode::Memory) == def_store, "use-def relationship");
3079
3080 Node* ctrl_use = use_store->in(MemNode::Control);
3081 Node* ctrl_def = def_store->in(MemNode::Control);
3082 if (ctrl_use == nullptr || ctrl_def == nullptr) {
3083 return CFGStatus::Failure;
3084 }
3085
3086 if (ctrl_use == ctrl_def) {
3087 // Same ctrl -> no RangeCheck in between.
3088 // Check: use_store must be the only use of def_store.
3089 if (def_store->outcnt() > 1) {
3090 return CFGStatus::Failure;
3091 }
3092 return CFGStatus::SuccessNoRangeCheck;
3093 }
3094
3095 // Different ctrl -> could have RangeCheck in between.
3096 // Check: 1. def_store only has these uses: use_store and MergeMem for uncommon trap, and
3097 // 2. ctrl separated by RangeCheck.
3098 if (def_store->outcnt() != 2) {
3099 return CFGStatus::Failure; // Cannot have exactly these uses: use_store and MergeMem for uncommon trap.
3100 }
3101 int use_store_out_idx = def_store->raw_out(0) == use_store ? 0 : 1;
3102 Node* merge_mem = def_store->raw_out(1 - use_store_out_idx)->isa_MergeMem();
3103 if (merge_mem == nullptr ||
3104 merge_mem->outcnt() != 1) {
3105 return CFGStatus::Failure; // Does not have MergeMem for uncommon trap.
3106 }
3107 if (!ctrl_use->is_IfProj() ||
3108 !ctrl_use->in(0)->is_RangeCheck() ||
3109 ctrl_use->in(0)->outcnt() != 2) {
3110 return CFGStatus::Failure; // Not RangeCheck.
3111 }
3112 ProjNode* other_proj = ctrl_use->as_IfProj()->other_if_proj();
3113 Node* trap = other_proj->is_uncommon_trap_proj(Deoptimization::Reason_range_check);
3114 if (trap != merge_mem->unique_out() ||
3115 ctrl_use->in(0)->in(0) != ctrl_def) {
3116 return CFGStatus::Failure; // Not RangeCheck with merge_mem leading to uncommon trap.
3117 }
3118
3119 return CFGStatus::SuccessWithRangeCheck;
3120 }
3121
3122 MergePrimitiveStores::Status MergePrimitiveStores::find_adjacent_use_store(const StoreNode* def_store) const {
3123 Status status_use = find_use_store(def_store);
3124 StoreNode* use_store = status_use.found_store();
3125 if (use_store != nullptr && !is_adjacent_pair(use_store, def_store)) {
3126 return Status::make_failure();
3127 }
3128 return status_use;
3129 }
3130
3131 MergePrimitiveStores::Status MergePrimitiveStores::find_adjacent_def_store(const StoreNode* use_store) const {
3132 Status status_def = find_def_store(use_store);
3133 StoreNode* def_store = status_def.found_store();
3134 if (def_store != nullptr && !is_adjacent_pair(use_store, def_store)) {
3135 return Status::make_failure();
3136 }
3137 return status_def;
3138 }
3139
3140 MergePrimitiveStores::Status MergePrimitiveStores::find_use_store(const StoreNode* def_store) const {
3141 Status status_use = find_use_store_unidirectional(def_store);
3142
3143 #ifdef ASSERT
3144 StoreNode* use_store = status_use.found_store();
3145 if (use_store != nullptr) {
3146 Status status_def = find_def_store_unidirectional(use_store);
3147 assert(status_def.found_store() == def_store &&
3148 status_def.found_range_check() == status_use.found_range_check(),
3149 "find_use_store and find_def_store must be symmetric");
3150 }
3151 #endif
3152
3153 return status_use;
3154 }
3155
3156 MergePrimitiveStores::Status MergePrimitiveStores::find_def_store(const StoreNode* use_store) const {
3157 Status status_def = find_def_store_unidirectional(use_store);
3158
3159 #ifdef ASSERT
3160 StoreNode* def_store = status_def.found_store();
3161 if (def_store != nullptr) {
3162 Status status_use = find_use_store_unidirectional(def_store);
3163 assert(status_use.found_store() == use_store &&
3164 status_use.found_range_check() == status_def.found_range_check(),
3165 "find_use_store and find_def_store must be symmetric");
3166 }
3167 #endif
3168
3169 return status_def;
3170 }
3171
3172 MergePrimitiveStores::Status MergePrimitiveStores::find_use_store_unidirectional(const StoreNode* def_store) const {
3173 assert(is_compatible_store(def_store), "precondition: must be compatible with _store");
3174
3175 for (DUIterator_Fast imax, i = def_store->fast_outs(imax); i < imax; i++) {
3176 StoreNode* use_store = def_store->fast_out(i)->isa_Store();
3177 if (is_compatible_store(use_store)) {
3178 return Status::make(use_store, cfg_status_for_pair(use_store, def_store));
3179 }
3180 }
3181
3182 return Status::make_failure();
3183 }
3184
3185 MergePrimitiveStores::Status MergePrimitiveStores::find_def_store_unidirectional(const StoreNode* use_store) const {
3186 assert(is_compatible_store(use_store), "precondition: must be compatible with _store");
3187
3188 StoreNode* def_store = use_store->in(MemNode::Memory)->isa_Store();
3189 if (!is_compatible_store(def_store)) {
3190 return Status::make_failure();
3191 }
3192
3193 return Status::make(def_store, cfg_status_for_pair(use_store, def_store));
3194 }
3195
3196 void MergePrimitiveStores::collect_merge_list(Node_List& merge_list) const {
3197 // The merged store can be at most 8 bytes.
3198 const uint merge_list_max_size = 8 / _store->memory_size();
3199 assert(merge_list_max_size >= 2 &&
3200 merge_list_max_size <= 8 &&
3201 is_power_of_2(merge_list_max_size),
3202 "must be 2, 4 or 8");
3203
3204 // Traverse up the chain of adjacent def stores.
3205 StoreNode* current = _store;
3206 merge_list.push(current);
3207 while (current != nullptr && merge_list.size() < merge_list_max_size) {
3208 Status status = find_adjacent_def_store(current);
3209 NOT_PRODUCT( if (is_trace_basic()) { tty->print("[TraceMergeStores] find def: "); status.print_on(tty); })
3210
3211 current = status.found_store();
3212 if (current != nullptr) {
3213 merge_list.push(current);
3214
3215 // We can have at most one RangeCheck.
3216 if (status.found_range_check()) {
3217 NOT_PRODUCT( if (is_trace_basic()) { tty->print_cr("[TraceMergeStores] found RangeCheck, stop traversal."); })
3218 break;
3219 }
3220 }
3221 }
3222
3223 NOT_PRODUCT( if (is_trace_basic()) { tty->print_cr("[TraceMergeStores] found:"); merge_list.dump(); })
3224
3225 // Truncate the merge_list to a power of 2.
3226 const uint pow2size = round_down_power_of_2(merge_list.size());
3227 assert(pow2size >= 2, "must be merging at least 2 stores");
3228 while (merge_list.size() > pow2size) { merge_list.pop(); }
3229
3230 NOT_PRODUCT( if (is_trace_basic()) { tty->print_cr("[TraceMergeStores] truncated:"); merge_list.dump(); })
3231 }
3232
3233 // Merge the input values of the smaller stores to a single larger input value.
3234 Node* MergePrimitiveStores::make_merged_input_value(const Node_List& merge_list) {
3235 int new_memory_size = _store->memory_size() * merge_list.size();
3236 Node* first = merge_list.at(merge_list.size()-1);
3237 Node* merged_input_value = nullptr;
3238 if (_store->in(MemNode::ValueIn)->Opcode() == Op_ConI) {
3239 assert(_value_order == ValueOrder::Const, "must match");
3240 // Pattern: [ConI, ConI, ...] -> new constant
3241 jlong con = 0;
3242 jlong bits_per_store = _store->memory_size() * 8;
3243 jlong mask = (((jlong)1) << bits_per_store) - 1;
3244 for (uint i = 0; i < merge_list.size(); i++) {
3245 jlong con_i = merge_list.at(i)->in(MemNode::ValueIn)->get_int();
3246 #ifdef VM_LITTLE_ENDIAN
3247 con = con << bits_per_store;
3248 con = con | (mask & con_i);
3249 #else // VM_LITTLE_ENDIAN
3250 con_i = (mask & con_i) << (i * bits_per_store);
3251 con = con | con_i;
3252 #endif // VM_LITTLE_ENDIAN
3253 }
3254 merged_input_value = _phase->longcon(con);
3255 } else {
3256 assert(_value_order == ValueOrder::Platform || _value_order == ValueOrder::Reverse, "must match");
3257 // Pattern: [base >> 24, base >> 16, base >> 8, base] -> base
3258 // | |
3259 // _store first
3260 //
3261 Node* hi = _store->in(MemNode::ValueIn);
3262 Node* lo = first->in(MemNode::ValueIn);
3263 #ifndef VM_LITTLE_ENDIAN
3264 // `_store` and `first` are swapped in the diagram above
3265 swap(hi, lo);
3266 #endif // !VM_LITTLE_ENDIAN
3267 if (_value_order == ValueOrder::Reverse) {
3268 swap(hi, lo);
3269 }
3270 Node const* hi_base;
3271 jint hi_shift;
3272 merged_input_value = lo;
3273 bool is_true = is_con_RShift(hi, hi_base, hi_shift, _phase);
3274 assert(is_true, "must detect con RShift");
3275 if (merged_input_value != hi_base && merged_input_value->Opcode() == Op_ConvL2I) {
3276 // look through
3277 merged_input_value = merged_input_value->in(1);
3278 }
3279 if (merged_input_value != hi_base) {
3280 // merged_input_value is not the base
3281 return nullptr;
3282 }
3283 }
3284
3285 if (_phase->type(merged_input_value)->isa_long() != nullptr && new_memory_size <= 4) {
3286 // Example:
3287 //
3288 // long base = ...;
3289 // a[0] = (byte)(base >> 0);
3290 // a[1] = (byte)(base >> 8);
3291 //
3292 merged_input_value = _phase->transform(new ConvL2INode(merged_input_value));
3293 }
3294
3295 assert((_phase->type(merged_input_value)->isa_int() != nullptr && new_memory_size <= 4) ||
3296 (_phase->type(merged_input_value)->isa_long() != nullptr && new_memory_size == 8),
3297 "merged_input_value is either int or long, and new_memory_size is small enough");
3298
3299 if (_value_order == ValueOrder::Reverse) {
3300 assert(_store->memory_size() == 1, "only implemented for bytes");
3301 if (new_memory_size == 8) {
3302 merged_input_value = _phase->transform(new ReverseBytesLNode(merged_input_value));
3303 } else if (new_memory_size == 4) {
3304 merged_input_value = _phase->transform(new ReverseBytesINode(merged_input_value));
3305 } else {
3306 assert(new_memory_size == 2, "sanity check");
3307 merged_input_value = _phase->transform(new ReverseBytesSNode(merged_input_value));
3308 }
3309 }
3310 return merged_input_value;
3311 }
3312
3313 // //
3314 // first_ctrl first_mem first_adr first_ctrl first_mem first_adr //
3315 // | | | | | | //
3316 // | | | | +---------------+ | //
3317 // | | | | | | | //
3318 // | | +---------+ | | +---------------+ //
3319 // | | | | | | | | //
3320 // +--------------+ | | v1 +------------------------------+ | | v1 //
3321 // | | | | | | | | | | | | //
3322 // RangeCheck first_store RangeCheck | | first_store //
3323 // | | | | | | | //
3324 // last_ctrl | +----> unc_trap last_ctrl | | +----> unc_trap //
3325 // | | ===> | | | //
3326 // +--------------+ | a2 v2 | | | //
3327 // | | | | | | | | //
3328 // | second_store | | | //
3329 // | | | | | [v1 v2 ... vn] //
3330 // ... ... | | | | //
3331 // | | | | | v //
3332 // +--------------+ | an vn +--------------+ | | merged_input_value //
3333 // | | | | | | | | //
3334 // last_store (= _store) merged_store //
3335 // //
3336 StoreNode* MergePrimitiveStores::make_merged_store(const Node_List& merge_list, Node* merged_input_value) {
3337 Node* first_store = merge_list.at(merge_list.size()-1);
3338 Node* last_ctrl = _store->in(MemNode::Control); // after (optional) RangeCheck
3339 Node* first_mem = first_store->in(MemNode::Memory);
3340 Node* first_adr = first_store->in(MemNode::Address);
3341
3342 const TypePtr* new_adr_type = _store->adr_type();
3343
3344 int new_memory_size = _store->memory_size() * merge_list.size();
3345 BasicType bt = T_ILLEGAL;
3346 switch (new_memory_size) {
3347 case 2: bt = T_SHORT; break;
3348 case 4: bt = T_INT; break;
3349 case 8: bt = T_LONG; break;
3350 }
3351
3352 StoreNode* merged_store = StoreNode::make(*_phase, last_ctrl, first_mem, first_adr,
3353 new_adr_type, merged_input_value, bt, MemNode::unordered);
3354
3355 // Marking the store mismatched is sufficient to prevent reordering, since array stores
3356 // are all on the same slice. Hence, we need no barriers.
3357 merged_store->set_mismatched_access();
3358
3359 // Constants above may now also be be packed -> put candidate on worklist
3360 _phase->is_IterGVN()->_worklist.push(first_mem);
3361
3362 return merged_store;
3363 }
3364
3365 #ifndef PRODUCT
3366 void MergePrimitiveStores::trace(const Node_List& merge_list, const Node* merged_input_value, const StoreNode* merged_store) const {
3367 stringStream ss;
3368 ss.print_cr("[TraceMergeStores]: Replace");
3369 for (int i = (int)merge_list.size() - 1; i >= 0; i--) {
3370 merge_list.at(i)->dump("\n", false, &ss);
3371 }
3372 ss.print_cr("[TraceMergeStores]: with");
3373 merged_input_value->dump("\n", false, &ss);
3374 merged_store->dump("\n", false, &ss);
3375 tty->print("%s", ss.as_string());
3376 }
3377 #endif
3378
3379 //------------------------------Ideal------------------------------------------
3380 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
3381 // When a store immediately follows a relevant allocation/initialization,
3382 // try to capture it into the initialization, or hoist it above.
3383 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3384 Node* p = MemNode::Ideal_common(phase, can_reshape);
3385 if (p) return (p == NodeSentinel) ? nullptr : p;
3386
3387 Node* mem = in(MemNode::Memory);
3388 Node* address = in(MemNode::Address);
3389 Node* value = in(MemNode::ValueIn);
3390 // Back-to-back stores to same address? Fold em up. Generally
3391 // unsafe if I have intervening uses.
3392 {
3393 Node* st = mem;
3394 // If Store 'st' has more than one use, we cannot fold 'st' away.
3395 // For example, 'st' might be the final state at a conditional
3396 // return. Or, 'st' might be used by some node which is live at
3397 // the same time 'st' is live, which might be unschedulable. So,
3398 // require exactly ONE user until such time as we clone 'mem' for
3399 // each of 'mem's uses (thus making the exactly-1-user-rule hold
3400 // true).
3401 while (st->is_Store() && st->outcnt() == 1) {
3402 // Looking at a dead closed cycle of memory?
3403 assert(st != st->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
3404 assert(Opcode() == st->Opcode() ||
3405 st->Opcode() == Op_StoreVector ||
3406 Opcode() == Op_StoreVector ||
3407 st->Opcode() == Op_StoreVectorScatter ||
3408 Opcode() == Op_StoreVectorScatter ||
3409 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw ||
3410 (Opcode() == Op_StoreL && st->Opcode() == Op_StoreI) || // expanded ClearArrayNode
3411 (Opcode() == Op_StoreI && st->Opcode() == Op_StoreL) || // initialization by arraycopy
3412 (is_mismatched_access() || st->as_Store()->is_mismatched_access()),
3413 "no mismatched stores, except on raw memory: %s %s", NodeClassNames[Opcode()], NodeClassNames[st->Opcode()]);
3414
3415 if (st->in(MemNode::Address)->eqv_uncast(address) &&
3416 st->as_Store()->memory_size() <= this->memory_size()) {
3417 Node* use = st->raw_out(0);
3418 if (phase->is_IterGVN()) {
3419 phase->is_IterGVN()->rehash_node_delayed(use);
3420 }
3421 // It's OK to do this in the parser, since DU info is always accurate,
3422 // and the parser always refers to nodes via SafePointNode maps.
3423 use->set_req_X(MemNode::Memory, st->in(MemNode::Memory), phase);
3424 return this;
3425 }
3426 st = st->in(MemNode::Memory);
3427 }
3428 }
3429
3430
3431 // Capture an unaliased, unconditional, simple store into an initializer.
3432 // Or, if it is independent of the allocation, hoist it above the allocation.
3433 if (ReduceFieldZeroing && /*can_reshape &&*/
3434 mem->is_Proj() && mem->in(0)->is_Initialize()) {
3435 InitializeNode* init = mem->in(0)->as_Initialize();
3436 intptr_t offset = init->can_capture_store(this, phase, can_reshape);
3437 if (offset > 0) {
3438 Node* moved = init->capture_store(this, offset, phase, can_reshape);
3439 // If the InitializeNode captured me, it made a raw copy of me,
3440 // and I need to disappear.
3441 if (moved != nullptr) {
3442 // %%% hack to ensure that Ideal returns a new node:
3443 mem = MergeMemNode::make(mem);
3444 return mem; // fold me away
3445 }
3446 }
3447 }
3448
3449 // Fold reinterpret cast into memory operation:
3450 // StoreX mem (MoveY2X v) => StoreY mem v
3451 if (value->is_Move()) {
3452 const Type* vt = value->in(1)->bottom_type();
3453 if (has_reinterpret_variant(vt)) {
3454 if (phase->C->post_loop_opts_phase()) {
3455 return convert_to_reinterpret_store(*phase, value->in(1), vt);
3456 } else {
3457 phase->C->record_for_post_loop_opts_igvn(this); // attempt the transformation once loop opts are over
3458 }
3459 }
3460 }
3461
3462 if (MergeStores && UseUnalignedAccesses) {
3463 if (phase->C->merge_stores_phase()) {
3464 MergePrimitiveStores merge(phase, this);
3465 Node* progress = merge.run();
3466 if (progress != nullptr) { return progress; }
3467 } else {
3468 // We need to wait with merging stores until RangeCheck smearing has removed the RangeChecks during
3469 // the post loops IGVN phase. If we do it earlier, then there may still be some RangeChecks between
3470 // the stores, and we merge the wrong sequence of stores.
3471 // Example:
3472 // StoreI RangeCheck StoreI StoreI RangeCheck StoreI
3473 // Apply MergeStores:
3474 // StoreI RangeCheck [ StoreL ] RangeCheck StoreI
3475 // Remove more RangeChecks:
3476 // StoreI [ StoreL ] StoreI
3477 // But now it would have been better to do this instead:
3478 // [ StoreL ] [ StoreL ]
3479 phase->C->record_for_merge_stores_igvn(this);
3480 }
3481 }
3482
3483 return nullptr; // No further progress
3484 }
3485
3486 //------------------------------Value-----------------------------------------
3487 const Type* StoreNode::Value(PhaseGVN* phase) const {
3488 // Either input is TOP ==> the result is TOP
3489 const Type *t1 = phase->type( in(MemNode::Memory) );
3490 if( t1 == Type::TOP ) return Type::TOP;
3491 const Type *t2 = phase->type( in(MemNode::Address) );
3492 if( t2 == Type::TOP ) return Type::TOP;
3493 const Type *t3 = phase->type( in(MemNode::ValueIn) );
3494 if( t3 == Type::TOP ) return Type::TOP;
3495 return Type::MEMORY;
3496 }
3497
3498 //------------------------------Identity---------------------------------------
3499 // Remove redundant stores:
3500 // Store(m, p, Load(m, p)) changes to m.
3501 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
3502 Node* StoreNode::Identity(PhaseGVN* phase) {
3503 Node* mem = in(MemNode::Memory);
3504 Node* adr = in(MemNode::Address);
3505 Node* val = in(MemNode::ValueIn);
3506
3507 Node* result = this;
3508
3509 // Load then Store? Then the Store is useless
3510 if (val->is_Load() &&
3511 val->in(MemNode::Address)->eqv_uncast(adr) &&
3512 val->in(MemNode::Memory )->eqv_uncast(mem) &&
3513 val->as_Load()->store_Opcode() == Opcode()) {
3514 // Ensure vector type is the same
3515 if (!is_StoreVector() || (mem->is_LoadVector() && as_StoreVector()->vect_type() == mem->as_LoadVector()->vect_type())) {
3516 result = mem;
3517 }
3518 }
3519
3520 // Two stores in a row of the same value?
3521 if (result == this &&
3522 mem->is_Store() &&
3523 mem->in(MemNode::Address)->eqv_uncast(adr) &&
3524 mem->in(MemNode::ValueIn)->eqv_uncast(val) &&
3525 mem->Opcode() == Opcode()) {
3526 if (!is_StoreVector()) {
3527 result = mem;
3528 } else {
3529 const StoreVectorNode* store_vector = as_StoreVector();
3530 const StoreVectorNode* mem_vector = mem->as_StoreVector();
3531 const Node* store_indices = store_vector->indices();
3532 const Node* mem_indices = mem_vector->indices();
3533 const Node* store_mask = store_vector->mask();
3534 const Node* mem_mask = mem_vector->mask();
3535 // Ensure types, indices, and masks match
3536 if (store_vector->vect_type() == mem_vector->vect_type() &&
3537 ((store_indices == nullptr) == (mem_indices == nullptr) &&
3538 (store_indices == nullptr || store_indices->eqv_uncast(mem_indices))) &&
3539 ((store_mask == nullptr) == (mem_mask == nullptr) &&
3540 (store_mask == nullptr || store_mask->eqv_uncast(mem_mask)))) {
3541 result = mem;
3542 }
3543 }
3544 }
3545
3546 // Store of zero anywhere into a freshly-allocated object?
3547 // Then the store is useless.
3548 // (It must already have been captured by the InitializeNode.)
3549 if (result == this &&
3550 ReduceFieldZeroing && phase->type(val)->is_zero_type()) {
3551 // a newly allocated object is already all-zeroes everywhere
3552 if (mem->is_Proj() && mem->in(0)->is_Allocate()) {
3553 result = mem;
3554 }
3555
3556 if (result == this) {
3557 // the store may also apply to zero-bits in an earlier object
3558 Node* prev_mem = find_previous_store(phase);
3559 // Steps (a), (b): Walk past independent stores to find an exact match.
3560 if (prev_mem != nullptr) {
3561 Node* prev_val = can_see_stored_value(prev_mem, phase);
3562 if (prev_val != nullptr && prev_val == val) {
3563 // prev_val and val might differ by a cast; it would be good
3564 // to keep the more informative of the two.
3565 result = mem;
3566 }
3567 }
3568 }
3569 }
3570
3571 PhaseIterGVN* igvn = phase->is_IterGVN();
3572 if (result != this && igvn != nullptr) {
3573 MemBarNode* trailing = trailing_membar();
3574 if (trailing != nullptr) {
3575 #ifdef ASSERT
3576 const TypeOopPtr* t_oop = phase->type(in(Address))->isa_oopptr();
3577 assert(t_oop == nullptr || t_oop->is_known_instance_field(), "only for non escaping objects");
3578 #endif
3579 trailing->remove(igvn);
3580 }
3581 }
3582
3583 return result;
3584 }
3585
3586 //------------------------------match_edge-------------------------------------
3587 // Do we Match on this edge index or not? Match only memory & value
3588 uint StoreNode::match_edge(uint idx) const {
3589 return idx == MemNode::Address || idx == MemNode::ValueIn;
3590 }
3591
3592 //------------------------------cmp--------------------------------------------
3593 // Do not common stores up together. They generally have to be split
3594 // back up anyways, so do not bother.
3595 bool StoreNode::cmp( const Node &n ) const {
3596 return (&n == this); // Always fail except on self
3597 }
3598
3599 //------------------------------Ideal_masked_input-----------------------------
3600 // Check for a useless mask before a partial-word store
3601 // (StoreB ... (AndI valIn conIa) )
3602 // If (conIa & mask == mask) this simplifies to
3603 // (StoreB ... (valIn) )
3604 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
3605 Node *val = in(MemNode::ValueIn);
3606 if( val->Opcode() == Op_AndI ) {
3607 const TypeInt *t = phase->type( val->in(2) )->isa_int();
3608 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
3609 set_req_X(MemNode::ValueIn, val->in(1), phase);
3610 return this;
3611 }
3612 }
3613 return nullptr;
3614 }
3615
3616
3617 //------------------------------Ideal_sign_extended_input----------------------
3618 // Check for useless sign-extension before a partial-word store
3619 // (StoreB ... (RShiftI _ (LShiftI _ v conIL) conIR))
3620 // If (conIL == conIR && conIR <= num_rejected_bits) this simplifies to
3621 // (StoreB ... (v))
3622 // If (conIL > conIR) under some conditions, it can be simplified into
3623 // (StoreB ... (LShiftI _ v (conIL - conIR)))
3624 // This case happens when the value of the store was itself a left shift, that
3625 // gets merged into the inner left shift of the sign-extension. For instance,
3626 // if we have
3627 // array_of_shorts[0] = (short)(v << 2)
3628 // We get a structure such as:
3629 // (StoreB ... (RShiftI _ (LShiftI _ (LShiftI _ v 2) 16) 16))
3630 // that is simplified into
3631 // (StoreB ... (RShiftI _ (LShiftI _ v 18) 16)).
3632 // It is thus useful to handle cases where conIL > conIR. But this simplification
3633 // does not always hold. Let's see in which cases it's valid.
3634 //
3635 // Let's assume we have the following 32 bits integer v:
3636 // +----------------------------------+
3637 // | v[0..31] |
3638 // +----------------------------------+
3639 // 31 0
3640 // that will be stuffed in 8 bits byte after a shift left and a shift right of
3641 // potentially different magnitudes.
3642 // We denote num_rejected_bits the number of bits of the discarded part. In this
3643 // case, num_rejected_bits == 24.
3644 //
3645 // Statement (proved further below in case analysis):
3646 // Given:
3647 // - 0 <= conIL < BitsPerJavaInteger (no wrap in shift, enforced by maskShiftAmount)
3648 // - 0 <= conIR < BitsPerJavaInteger (no wrap in shift, enforced by maskShiftAmount)
3649 // - conIL >= conIR
3650 // - num_rejected_bits >= conIR
3651 // Then this form:
3652 // (RShiftI _ (LShiftI _ v conIL) conIR)
3653 // can be replaced with this form:
3654 // (LShiftI _ v (conIL-conIR))
3655 //
3656 // Note: We only have to show that the non-rejected lowest bits (8 bits for byte)
3657 // have to be correct, as the higher bits are rejected / truncated by the store.
3658 //
3659 // The hypotheses
3660 // 0 <= conIL < BitsPerJavaInteger
3661 // 0 <= conIR < BitsPerJavaInteger
3662 // are ensured by maskShiftAmount (called from ::Ideal of shift nodes). Indeed,
3663 // (v << 31) << 2 must be simplified into 0, not into v << 33 (which is equivalent
3664 // to v << 1).
3665 //
3666 //
3667 // If you don't like case analysis, jump after the conclusion.
3668 // ### Case 1 : conIL == conIR
3669 // ###### Case 1.1: conIL == conIR == num_rejected_bits
3670 // If we do the shift left then right by 24 bits, we get:
3671 // after: v << 24
3672 // +---------+------------------------+
3673 // | v[0..7] | 0 |
3674 // +---------+------------------------+
3675 // 31 24 23 0
3676 // after: (v << 24) >> 24
3677 // +------------------------+---------+
3678 // | sign bit | v[0..7] |
3679 // +------------------------+---------+
3680 // 31 8 7 0
3681 // The non-rejected bits (bits kept by the store, that is the 8 lower bits of the
3682 // result) are the same before and after, so, indeed, simplifying is correct.
3683
3684 // ###### Case 1.2: conIL == conIR < num_rejected_bits
3685 // If we do the shift left then right by 22 bits, we get:
3686 // after: v << 22
3687 // +---------+------------------------+
3688 // | v[0..9] | 0 |
3689 // +---------+------------------------+
3690 // 31 22 21 0
3691 // after: (v << 22) >> 22
3692 // +------------------------+---------+
3693 // | sign bit | v[0..9] |
3694 // +------------------------+---------+
3695 // 31 10 9 0
3696 // The non-rejected bits are the 8 lower bits of v. The bits 8 and 9 of v are still
3697 // present in (v << 22) >> 22 but will be dropped by the store. The simplification is
3698 // still correct.
3699
3700 // ###### But! Case 1.3: conIL == conIR > num_rejected_bits
3701 // If we do the shift left then right by 26 bits, we get:
3702 // after: v << 26
3703 // +---------+------------------------+
3704 // | v[0..5] | 0 |
3705 // +---------+------------------------+
3706 // 31 26 25 0
3707 // after: (v << 26) >> 26
3708 // +------------------------+---------+
3709 // | sign bit | v[0..5] |
3710 // +------------------------+---------+
3711 // 31 6 5 0
3712 // The non-rejected bits are made of
3713 // - 0-5 => the bits 0 to 5 of v
3714 // - 6-7 => the sign bit of v[0..5] (that is v[5])
3715 // Simplifying this as v is not correct.
3716 // The condition conIR <= num_rejected_bits is indeed necessary in Case 1
3717 //
3718 // ### Case 2: conIL > conIR
3719 // ###### Case 2.1: num_rejected_bits == conIR
3720 // We take conIL == 26 for this example.
3721 // after: v << 26
3722 // +---------+------------------------+
3723 // | v[0..5] | 0 |
3724 // +---------+------------------------+
3725 // 31 26 25 0
3726 // after: (v << 26) >> 24
3727 // +------------------+---------+-----+
3728 // | sign bit | v[0..5] | 0 |
3729 // +------------------+---------+-----+
3730 // 31 8 7 2 1 0
3731 // The non-rejected bits are the 8 lower ones of (v << conIL - conIR).
3732 // The bits 6 and 7 of v have been thrown away after the shift left.
3733 // The simplification is still correct.
3734 //
3735 // ###### Case 2.2: num_rejected_bits > conIR.
3736 // Let's say conIL == 26 and conIR == 22.
3737 // after: v << 26
3738 // +---------+------------------------+
3739 // | v[0..5] | 0 |
3740 // +---------+------------------------+
3741 // 31 26 25 0
3742 // after: (v << 26) >> 22
3743 // +------------------+---------+-----+
3744 // | sign bit | v[0..5] | 0 |
3745 // +------------------+---------+-----+
3746 // 31 10 9 4 3 0
3747 // The bits non-rejected by the store are exactly the 8 lower ones of (v << (conIL - conIR)):
3748 // - 0-3 => 0
3749 // - 4-7 => bits 0 to 3 of v
3750 // The simplification is still correct.
3751 // The bits 4 and 5 of v are still present in (v << (conIL - conIR)) but they don't
3752 // matter as they are not in the 8 lower bits: they will be cut out by the store.
3753 //
3754 // ###### But! Case 2.3: num_rejected_bits < conIR.
3755 // Let's see that this case is not as easy to simplify.
3756 // Let's say conIL == 28 and conIR == 26.
3757 // after: v << 28
3758 // +---------+------------------------+
3759 // | v[0..3] | 0 |
3760 // +---------+------------------------+
3761 // 31 28 27 0
3762 // after: (v << 28) >> 26
3763 // +------------------+---------+-----+
3764 // | sign bit | v[0..3] | 0 |
3765 // +------------------+---------+-----+
3766 // 31 6 5 2 1 0
3767 // The non-rejected bits are made of
3768 // - 0-1 => 0
3769 // - 2-5 => the bits 0 to 3 of v
3770 // - 6-7 => the sign bit of v[0..3] (that is v[3])
3771 // Simplifying this as (v << 2) is not correct.
3772 // The condition conIR <= num_rejected_bits is indeed necessary in Case 2.
3773 //
3774 // ### Conclusion:
3775 // Our hypotheses are indeed sufficient:
3776 // - 0 <= conIL < BitsPerJavaInteger
3777 // - 0 <= conIR < BitsPerJavaInteger
3778 // - conIL >= conIR
3779 // - num_rejected_bits >= conIR
3780 //
3781 // ### A rationale without case analysis:
3782 // After the shift left, conIL upper bits of v are discarded and conIL lower bit
3783 // zeroes are added. After the shift right, conIR lower bits of the previous result
3784 // are discarded. If conIL >= conIR, we discard only the zeroes we made up during
3785 // the shift left, but if conIL < conIR, then we discard also lower bits of v. But
3786 // the point of the simplification is to get an expression of the form
3787 // (v << (conIL - conIR)). This expression discard only higher bits of v, thus the
3788 // simplification is not correct if conIL < conIR.
3789 //
3790 // Moreover, after the shift right, the higher bit of (v << conIL) is repeated on the
3791 // conIR higher bits of ((v << conIL) >> conIR), it's the sign-extension. If
3792 // conIR > num_rejected_bits, then at least one artificial copy of this sign bit will
3793 // be in the window of the store. Thus ((v << conIL) >> conIR) is not equivalent to
3794 // (v << (conIL-conIR)) if conIR > num_rejected_bits.
3795 //
3796 // We do not treat the case conIL < conIR here since the point of this function is
3797 // to skip sign-extensions (that is conIL == conIR == num_rejected_bits). The need
3798 // of treating conIL > conIR comes from the cases where the sign-extended value is
3799 // also left-shift expression. Computing the sign-extension of a right-shift expression
3800 // doesn't yield a situation such as
3801 // (StoreB ... (RShiftI _ (LShiftI _ v conIL) conIR))
3802 // where conIL < conIR.
3803 Node* StoreNode::Ideal_sign_extended_input(PhaseGVN* phase, int num_rejected_bits) {
3804 Node* shr = in(MemNode::ValueIn);
3805 if (shr->Opcode() == Op_RShiftI) {
3806 const TypeInt* conIR = phase->type(shr->in(2))->isa_int();
3807 if (conIR != nullptr && conIR->is_con() && conIR->get_con() >= 0 && conIR->get_con() < BitsPerJavaInteger && conIR->get_con() <= num_rejected_bits) {
3808 Node* shl = shr->in(1);
3809 if (shl->Opcode() == Op_LShiftI) {
3810 const TypeInt* conIL = phase->type(shl->in(2))->isa_int();
3811 if (conIL != nullptr && conIL->is_con() && conIL->get_con() >= 0 && conIL->get_con() < BitsPerJavaInteger) {
3812 if (conIL->get_con() == conIR->get_con()) {
3813 set_req_X(MemNode::ValueIn, shl->in(1), phase);
3814 return this;
3815 }
3816 if (conIL->get_con() > conIR->get_con()) {
3817 Node* new_shl = phase->transform(new LShiftINode(shl->in(1), phase->intcon(conIL->get_con() - conIR->get_con())));
3818 set_req_X(MemNode::ValueIn, new_shl, phase);
3819 return this;
3820 }
3821 }
3822 }
3823 }
3824 }
3825 return nullptr;
3826 }
3827
3828 //------------------------------value_never_loaded-----------------------------------
3829 // Determine whether there are any possible loads of the value stored.
3830 // For simplicity, we actually check if there are any loads from the
3831 // address stored to, not just for loads of the value stored by this node.
3832 //
3833 bool StoreNode::value_never_loaded(PhaseValues* phase) const {
3834 Node *adr = in(Address);
3835 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
3836 if (adr_oop == nullptr)
3837 return false;
3838 if (!adr_oop->is_known_instance_field())
3839 return false; // if not a distinct instance, there may be aliases of the address
3840 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
3841 Node *use = adr->fast_out(i);
3842 if (use->is_Load() || use->is_LoadStore()) {
3843 return false;
3844 }
3845 }
3846 return true;
3847 }
3848
3849 MemBarNode* StoreNode::trailing_membar() const {
3850 if (is_release()) {
3851 MemBarNode* trailing_mb = nullptr;
3852 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
3853 Node* u = fast_out(i);
3854 if (u->is_MemBar()) {
3855 if (u->as_MemBar()->trailing_store()) {
3856 assert(u->Opcode() == Op_MemBarVolatile, "");
3857 assert(trailing_mb == nullptr, "only one");
3858 trailing_mb = u->as_MemBar();
3859 #ifdef ASSERT
3860 Node* leading = u->as_MemBar()->leading_membar();
3861 assert(leading->Opcode() == Op_MemBarRelease, "incorrect membar");
3862 assert(leading->as_MemBar()->leading_store(), "incorrect membar pair");
3863 assert(leading->as_MemBar()->trailing_membar() == u, "incorrect membar pair");
3864 #endif
3865 } else {
3866 assert(u->as_MemBar()->standalone(), "");
3867 }
3868 }
3869 }
3870 return trailing_mb;
3871 }
3872 return nullptr;
3873 }
3874
3875
3876 //=============================================================================
3877 //------------------------------Ideal------------------------------------------
3878 // If the store is from an AND mask that leaves the low bits untouched, then
3879 // we can skip the AND operation. If the store is from a sign-extension
3880 // (a left shift, then right shift) we can skip both.
3881 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
3882 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
3883 if( progress != nullptr ) return progress;
3884
3885 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
3886 if( progress != nullptr ) return progress;
3887
3888 // Finally check the default case
3889 return StoreNode::Ideal(phase, can_reshape);
3890 }
3891
3892 //=============================================================================
3893 //------------------------------Ideal------------------------------------------
3894 // If the store is from an AND mask that leaves the low bits untouched, then
3895 // we can skip the AND operation
3896 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
3897 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
3898 if( progress != nullptr ) return progress;
3899
3900 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
3901 if( progress != nullptr ) return progress;
3902
3903 // Finally check the default case
3904 return StoreNode::Ideal(phase, can_reshape);
3905 }
3906
3907 //=============================================================================
3908 //----------------------------------SCMemProjNode------------------------------
3909 const Type* SCMemProjNode::Value(PhaseGVN* phase) const
3910 {
3911 if (in(0) == nullptr || phase->type(in(0)) == Type::TOP) {
3912 return Type::TOP;
3913 }
3914 return bottom_type();
3915 }
3916
3917 //=============================================================================
3918 //----------------------------------LoadStoreNode------------------------------
3919 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required )
3920 : Node(required),
3921 _type(rt),
3922 _adr_type(at),
3923 _barrier_data(0)
3924 {
3925 init_req(MemNode::Control, c );
3926 init_req(MemNode::Memory , mem);
3927 init_req(MemNode::Address, adr);
3928 init_req(MemNode::ValueIn, val);
3929 init_class_id(Class_LoadStore);
3930 }
3931
3932 //------------------------------Value-----------------------------------------
3933 const Type* LoadStoreNode::Value(PhaseGVN* phase) const {
3934 // Either input is TOP ==> the result is TOP
3935 if (!in(MemNode::Control) || phase->type(in(MemNode::Control)) == Type::TOP) {
3936 return Type::TOP;
3937 }
3938 const Type* t = phase->type(in(MemNode::Memory));
3939 if (t == Type::TOP) {
3940 return Type::TOP;
3941 }
3942 t = phase->type(in(MemNode::Address));
3943 if (t == Type::TOP) {
3944 return Type::TOP;
3945 }
3946 t = phase->type(in(MemNode::ValueIn));
3947 if (t == Type::TOP) {
3948 return Type::TOP;
3949 }
3950 return bottom_type();
3951 }
3952
3953 uint LoadStoreNode::ideal_reg() const {
3954 return _type->ideal_reg();
3955 }
3956
3957 // This method conservatively checks if the result of a LoadStoreNode is
3958 // used, that is, if it returns true, then it is definitely the case that
3959 // the result of the node is not needed.
3960 // For example, GetAndAdd can be matched into a lock_add instead of a
3961 // lock_xadd if the result of LoadStoreNode::result_not_used() is true
3962 bool LoadStoreNode::result_not_used() const {
3963 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
3964 Node *x = fast_out(i);
3965 if (x->Opcode() == Op_SCMemProj) {
3966 continue;
3967 }
3968 if (x->bottom_type() == TypeTuple::MEMBAR &&
3969 !x->is_Call() &&
3970 x->Opcode() != Op_Blackhole) {
3971 continue;
3972 }
3973 return false;
3974 }
3975 return true;
3976 }
3977
3978 MemBarNode* LoadStoreNode::trailing_membar() const {
3979 MemBarNode* trailing = nullptr;
3980 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
3981 Node* u = fast_out(i);
3982 if (u->is_MemBar()) {
3983 if (u->as_MemBar()->trailing_load_store()) {
3984 assert(u->Opcode() == Op_MemBarAcquire, "");
3985 assert(trailing == nullptr, "only one");
3986 trailing = u->as_MemBar();
3987 #ifdef ASSERT
3988 Node* leading = trailing->leading_membar();
3989 assert(support_IRIW_for_not_multiple_copy_atomic_cpu || leading->Opcode() == Op_MemBarRelease, "incorrect membar");
3990 assert(leading->as_MemBar()->leading_load_store(), "incorrect membar pair");
3991 assert(leading->as_MemBar()->trailing_membar() == trailing, "incorrect membar pair");
3992 #endif
3993 } else {
3994 assert(u->as_MemBar()->standalone(), "wrong barrier kind");
3995 }
3996 }
3997 }
3998
3999 return trailing;
4000 }
4001
4002 uint LoadStoreNode::size_of() const { return sizeof(*this); }
4003
4004 //=============================================================================
4005 //----------------------------------LoadStoreConditionalNode--------------------
4006 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, nullptr, TypeInt::BOOL, 5) {
4007 init_req(ExpectedIn, ex );
4008 }
4009
4010 const Type* LoadStoreConditionalNode::Value(PhaseGVN* phase) const {
4011 // Either input is TOP ==> the result is TOP
4012 const Type* t = phase->type(in(ExpectedIn));
4013 if (t == Type::TOP) {
4014 return Type::TOP;
4015 }
4016 return LoadStoreNode::Value(phase);
4017 }
4018
4019 //=============================================================================
4020 //-------------------------------adr_type--------------------------------------
4021 const TypePtr* ClearArrayNode::adr_type() const {
4022 Node *adr = in(3);
4023 if (adr == nullptr) return nullptr; // node is dead
4024 return MemNode::calculate_adr_type(adr->bottom_type());
4025 }
4026
4027 //------------------------------match_edge-------------------------------------
4028 // Do we Match on this edge index or not? Do not match memory
4029 uint ClearArrayNode::match_edge(uint idx) const {
4030 return idx > 1;
4031 }
4032
4033 //------------------------------Identity---------------------------------------
4034 // Clearing a zero length array does nothing
4035 Node* ClearArrayNode::Identity(PhaseGVN* phase) {
4036 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
4037 }
4038
4039 //------------------------------Idealize---------------------------------------
4040 // Clearing a short array is faster with stores
4041 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4042 // Already know this is a large node, do not try to ideal it
4043 if (_is_large) return nullptr;
4044
4045 const int unit = BytesPerLong;
4046 const TypeX* t = phase->type(in(2))->isa_intptr_t();
4047 if (!t) return nullptr;
4048 if (!t->is_con()) return nullptr;
4049 intptr_t raw_count = t->get_con();
4050 intptr_t size = raw_count;
4051 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
4052 // Clearing nothing uses the Identity call.
4053 // Negative clears are possible on dead ClearArrays
4054 // (see jck test stmt114.stmt11402.val).
4055 if (size <= 0 || size % unit != 0) return nullptr;
4056 intptr_t count = size / unit;
4057 // Length too long; communicate this to matchers and assemblers.
4058 // Assemblers are responsible to produce fast hardware clears for it.
4059 if (size > InitArrayShortSize) {
4060 return new ClearArrayNode(in(0), in(1), in(2), in(3), true);
4061 } else if (size > 2 && Matcher::match_rule_supported_vector(Op_ClearArray, 4, T_LONG)) {
4062 return nullptr;
4063 }
4064 if (!IdealizeClearArrayNode) return nullptr;
4065 Node *mem = in(1);
4066 if( phase->type(mem)==Type::TOP ) return nullptr;
4067 Node *adr = in(3);
4068 const Type* at = phase->type(adr);
4069 if( at==Type::TOP ) return nullptr;
4070 const TypePtr* atp = at->isa_ptr();
4071 // adjust atp to be the correct array element address type
4072 if (atp == nullptr) atp = TypePtr::BOTTOM;
4073 else atp = atp->add_offset(Type::OffsetBot);
4074 // Get base for derived pointer purposes
4075 if( adr->Opcode() != Op_AddP ) Unimplemented();
4076 Node *base = adr->in(1);
4077
4078 Node *zero = phase->makecon(TypeLong::ZERO);
4079 Node *off = phase->MakeConX(BytesPerLong);
4080 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
4081 count--;
4082 while( count-- ) {
4083 mem = phase->transform(mem);
4084 adr = phase->transform(new AddPNode(base,adr,off));
4085 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
4086 }
4087 return mem;
4088 }
4089
4090 //----------------------------step_through----------------------------------
4091 // Return allocation input memory edge if it is different instance
4092 // or itself if it is the one we are looking for.
4093 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseValues* phase) {
4094 Node* n = *np;
4095 assert(n->is_ClearArray(), "sanity");
4096 intptr_t offset;
4097 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
4098 // This method is called only before Allocate nodes are expanded
4099 // during macro nodes expansion. Before that ClearArray nodes are
4100 // only generated in PhaseMacroExpand::generate_arraycopy() (before
4101 // Allocate nodes are expanded) which follows allocations.
4102 assert(alloc != nullptr, "should have allocation");
4103 if (alloc->_idx == instance_id) {
4104 // Can not bypass initialization of the instance we are looking for.
4105 return false;
4106 }
4107 // Otherwise skip it.
4108 InitializeNode* init = alloc->initialization();
4109 if (init != nullptr)
4110 *np = init->in(TypeFunc::Memory);
4111 else
4112 *np = alloc->in(TypeFunc::Memory);
4113 return true;
4114 }
4115
4116 //----------------------------clear_memory-------------------------------------
4117 // Generate code to initialize object storage to zero.
4118 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
4119 intptr_t start_offset,
4120 Node* end_offset,
4121 PhaseGVN* phase) {
4122 intptr_t offset = start_offset;
4123
4124 int unit = BytesPerLong;
4125 if ((offset % unit) != 0) {
4126 Node* adr = new AddPNode(dest, dest, phase->MakeConX(offset));
4127 adr = phase->transform(adr);
4128 const TypePtr* atp = TypeRawPtr::BOTTOM;
4129 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
4130 mem = phase->transform(mem);
4131 offset += BytesPerInt;
4132 }
4133 assert((offset % unit) == 0, "");
4134
4135 // Initialize the remaining stuff, if any, with a ClearArray.
4136 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase);
4137 }
4138
4139 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
4140 Node* start_offset,
4141 Node* end_offset,
4142 PhaseGVN* phase) {
4143 if (start_offset == end_offset) {
4144 // nothing to do
4145 return mem;
4146 }
4147
4148 int unit = BytesPerLong;
4149 Node* zbase = start_offset;
4150 Node* zend = end_offset;
4151
4152 // Scale to the unit required by the CPU:
4153 if (!Matcher::init_array_count_is_in_bytes) {
4154 Node* shift = phase->intcon(exact_log2(unit));
4155 zbase = phase->transform(new URShiftXNode(zbase, shift) );
4156 zend = phase->transform(new URShiftXNode(zend, shift) );
4157 }
4158
4159 // Bulk clear double-words
4160 Node* zsize = phase->transform(new SubXNode(zend, zbase) );
4161 Node* adr = phase->transform(new AddPNode(dest, dest, start_offset) );
4162 mem = new ClearArrayNode(ctl, mem, zsize, adr, false);
4163 return phase->transform(mem);
4164 }
4165
4166 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
4167 intptr_t start_offset,
4168 intptr_t end_offset,
4169 PhaseGVN* phase) {
4170 if (start_offset == end_offset) {
4171 // nothing to do
4172 return mem;
4173 }
4174
4175 assert((end_offset % BytesPerInt) == 0, "odd end offset");
4176 intptr_t done_offset = end_offset;
4177 if ((done_offset % BytesPerLong) != 0) {
4178 done_offset -= BytesPerInt;
4179 }
4180 if (done_offset > start_offset) {
4181 mem = clear_memory(ctl, mem, dest,
4182 start_offset, phase->MakeConX(done_offset), phase);
4183 }
4184 if (done_offset < end_offset) { // emit the final 32-bit store
4185 Node* adr = new AddPNode(dest, dest, phase->MakeConX(done_offset));
4186 adr = phase->transform(adr);
4187 const TypePtr* atp = TypeRawPtr::BOTTOM;
4188 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
4189 mem = phase->transform(mem);
4190 done_offset += BytesPerInt;
4191 }
4192 assert(done_offset == end_offset, "");
4193 return mem;
4194 }
4195
4196 //=============================================================================
4197 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
4198 : MultiNode(TypeFunc::Parms + (precedent == nullptr? 0: 1)),
4199 _adr_type(C->get_adr_type(alias_idx)), _kind(Standalone)
4200 #ifdef ASSERT
4201 , _pair_idx(0)
4202 #endif
4203 {
4204 init_class_id(Class_MemBar);
4205 Node* top = C->top();
4206 init_req(TypeFunc::I_O,top);
4207 init_req(TypeFunc::FramePtr,top);
4208 init_req(TypeFunc::ReturnAdr,top);
4209 if (precedent != nullptr)
4210 init_req(TypeFunc::Parms, precedent);
4211 }
4212
4213 //------------------------------cmp--------------------------------------------
4214 uint MemBarNode::hash() const { return NO_HASH; }
4215 bool MemBarNode::cmp( const Node &n ) const {
4216 return (&n == this); // Always fail except on self
4217 }
4218
4219 //------------------------------make-------------------------------------------
4220 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
4221 switch (opcode) {
4222 case Op_MemBarAcquire: return new MemBarAcquireNode(C, atp, pn);
4223 case Op_LoadFence: return new LoadFenceNode(C, atp, pn);
4224 case Op_MemBarRelease: return new MemBarReleaseNode(C, atp, pn);
4225 case Op_StoreFence: return new StoreFenceNode(C, atp, pn);
4226 case Op_MemBarStoreStore: return new MemBarStoreStoreNode(C, atp, pn);
4227 case Op_StoreStoreFence: return new StoreStoreFenceNode(C, atp, pn);
4228 case Op_MemBarAcquireLock: return new MemBarAcquireLockNode(C, atp, pn);
4229 case Op_MemBarReleaseLock: return new MemBarReleaseLockNode(C, atp, pn);
4230 case Op_MemBarVolatile: return new MemBarVolatileNode(C, atp, pn);
4231 case Op_MemBarCPUOrder: return new MemBarCPUOrderNode(C, atp, pn);
4232 case Op_OnSpinWait: return new OnSpinWaitNode(C, atp, pn);
4233 case Op_Initialize: return new InitializeNode(C, atp, pn);
4234 default: ShouldNotReachHere(); return nullptr;
4235 }
4236 }
4237
4238 void MemBarNode::remove(PhaseIterGVN *igvn) {
4239 if (outcnt() != 2) {
4240 assert(Opcode() == Op_Initialize, "Only seen when there are no use of init memory");
4241 assert(outcnt() == 1, "Only control then");
4242 }
4243 if (trailing_store() || trailing_load_store()) {
4244 MemBarNode* leading = leading_membar();
4245 if (leading != nullptr) {
4246 assert(leading->trailing_membar() == this, "inconsistent leading/trailing membars");
4247 leading->remove(igvn);
4248 }
4249 }
4250 if (proj_out_or_null(TypeFunc::Memory) != nullptr) {
4251 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
4252 }
4253 if (proj_out_or_null(TypeFunc::Control) != nullptr) {
4254 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
4255 }
4256 }
4257
4258 //------------------------------Ideal------------------------------------------
4259 // Return a node which is more "ideal" than the current node. Strip out
4260 // control copies
4261 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4262 if (remove_dead_region(phase, can_reshape)) return this;
4263 // Don't bother trying to transform a dead node
4264 if (in(0) && in(0)->is_top()) {
4265 return nullptr;
4266 }
4267
4268 bool progress = false;
4269 // Eliminate volatile MemBars for scalar replaced objects.
4270 if (can_reshape && req() == (Precedent+1)) {
4271 bool eliminate = false;
4272 int opc = Opcode();
4273 if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) {
4274 // Volatile field loads and stores.
4275 Node* my_mem = in(MemBarNode::Precedent);
4276 // The MembarAquire may keep an unused LoadNode alive through the Precedent edge
4277 if ((my_mem != nullptr) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) {
4278 // if the Precedent is a decodeN and its input (a Load) is used at more than one place,
4279 // replace this Precedent (decodeN) with the Load instead.
4280 if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1)) {
4281 Node* load_node = my_mem->in(1);
4282 set_req(MemBarNode::Precedent, load_node);
4283 phase->is_IterGVN()->_worklist.push(my_mem);
4284 my_mem = load_node;
4285 } else {
4286 assert(my_mem->unique_out() == this, "sanity");
4287 assert(!trailing_load_store(), "load store node can't be eliminated");
4288 del_req(Precedent);
4289 phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later
4290 my_mem = nullptr;
4291 }
4292 progress = true;
4293 }
4294 if (my_mem != nullptr && my_mem->is_Mem()) {
4295 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
4296 // Check for scalar replaced object reference.
4297 if( t_oop != nullptr && t_oop->is_known_instance_field() &&
4298 t_oop->offset() != Type::OffsetBot &&
4299 t_oop->offset() != Type::OffsetTop) {
4300 eliminate = true;
4301 }
4302 }
4303 } else if (opc == Op_MemBarRelease || (UseStoreStoreForCtor && opc == Op_MemBarStoreStore)) {
4304 // Final field stores.
4305 Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent));
4306 if ((alloc != nullptr) && alloc->is_Allocate() &&
4307 alloc->as_Allocate()->does_not_escape_thread()) {
4308 // The allocated object does not escape.
4309 eliminate = true;
4310 }
4311 }
4312 if (eliminate) {
4313 // Replace MemBar projections by its inputs.
4314 PhaseIterGVN* igvn = phase->is_IterGVN();
4315 remove(igvn);
4316 // Must return either the original node (now dead) or a new node
4317 // (Do not return a top here, since that would break the uniqueness of top.)
4318 return new ConINode(TypeInt::ZERO);
4319 }
4320 }
4321 return progress ? this : nullptr;
4322 }
4323
4324 //------------------------------Value------------------------------------------
4325 const Type* MemBarNode::Value(PhaseGVN* phase) const {
4326 if( !in(0) ) return Type::TOP;
4327 if( phase->type(in(0)) == Type::TOP )
4328 return Type::TOP;
4329 return TypeTuple::MEMBAR;
4330 }
4331
4332 //------------------------------match------------------------------------------
4333 // Construct projections for memory.
4334 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) {
4335 switch (proj->_con) {
4336 case TypeFunc::Control:
4337 case TypeFunc::Memory:
4338 return new MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
4339 }
4340 ShouldNotReachHere();
4341 return nullptr;
4342 }
4343
4344 void MemBarNode::set_store_pair(MemBarNode* leading, MemBarNode* trailing) {
4345 trailing->_kind = TrailingStore;
4346 leading->_kind = LeadingStore;
4347 #ifdef ASSERT
4348 trailing->_pair_idx = leading->_idx;
4349 leading->_pair_idx = leading->_idx;
4350 #endif
4351 }
4352
4353 void MemBarNode::set_load_store_pair(MemBarNode* leading, MemBarNode* trailing) {
4354 trailing->_kind = TrailingLoadStore;
4355 leading->_kind = LeadingLoadStore;
4356 #ifdef ASSERT
4357 trailing->_pair_idx = leading->_idx;
4358 leading->_pair_idx = leading->_idx;
4359 #endif
4360 }
4361
4362 MemBarNode* MemBarNode::trailing_membar() const {
4363 ResourceMark rm;
4364 Node* trailing = (Node*)this;
4365 VectorSet seen;
4366 Node_Stack multis(0);
4367 do {
4368 Node* c = trailing;
4369 uint i = 0;
4370 do {
4371 trailing = nullptr;
4372 for (; i < c->outcnt(); i++) {
4373 Node* next = c->raw_out(i);
4374 if (next != c && next->is_CFG()) {
4375 if (c->is_MultiBranch()) {
4376 if (multis.node() == c) {
4377 multis.set_index(i+1);
4378 } else {
4379 multis.push(c, i+1);
4380 }
4381 }
4382 trailing = next;
4383 break;
4384 }
4385 }
4386 if (trailing != nullptr && !seen.test_set(trailing->_idx)) {
4387 break;
4388 }
4389 while (multis.size() > 0) {
4390 c = multis.node();
4391 i = multis.index();
4392 if (i < c->req()) {
4393 break;
4394 }
4395 multis.pop();
4396 }
4397 } while (multis.size() > 0);
4398 } while (!trailing->is_MemBar() || !trailing->as_MemBar()->trailing());
4399
4400 MemBarNode* mb = trailing->as_MemBar();
4401 assert((mb->_kind == TrailingStore && _kind == LeadingStore) ||
4402 (mb->_kind == TrailingLoadStore && _kind == LeadingLoadStore), "bad trailing membar");
4403 assert(mb->_pair_idx == _pair_idx, "bad trailing membar");
4404 return mb;
4405 }
4406
4407 MemBarNode* MemBarNode::leading_membar() const {
4408 ResourceMark rm;
4409 VectorSet seen;
4410 Node_Stack regions(0);
4411 Node* leading = in(0);
4412 while (leading != nullptr && (!leading->is_MemBar() || !leading->as_MemBar()->leading())) {
4413 while (leading == nullptr || leading->is_top() || seen.test_set(leading->_idx)) {
4414 leading = nullptr;
4415 while (regions.size() > 0 && leading == nullptr) {
4416 Node* r = regions.node();
4417 uint i = regions.index();
4418 if (i < r->req()) {
4419 leading = r->in(i);
4420 regions.set_index(i+1);
4421 } else {
4422 regions.pop();
4423 }
4424 }
4425 if (leading == nullptr) {
4426 assert(regions.size() == 0, "all paths should have been tried");
4427 return nullptr;
4428 }
4429 }
4430 if (leading->is_Region()) {
4431 regions.push(leading, 2);
4432 leading = leading->in(1);
4433 } else {
4434 leading = leading->in(0);
4435 }
4436 }
4437 #ifdef ASSERT
4438 Unique_Node_List wq;
4439 wq.push((Node*)this);
4440 uint found = 0;
4441 for (uint i = 0; i < wq.size(); i++) {
4442 Node* n = wq.at(i);
4443 if (n->is_Region()) {
4444 for (uint j = 1; j < n->req(); j++) {
4445 Node* in = n->in(j);
4446 if (in != nullptr && !in->is_top()) {
4447 wq.push(in);
4448 }
4449 }
4450 } else {
4451 if (n->is_MemBar() && n->as_MemBar()->leading()) {
4452 assert(n == leading, "consistency check failed");
4453 found++;
4454 } else {
4455 Node* in = n->in(0);
4456 if (in != nullptr && !in->is_top()) {
4457 wq.push(in);
4458 }
4459 }
4460 }
4461 }
4462 assert(found == 1 || (found == 0 && leading == nullptr), "consistency check failed");
4463 #endif
4464 if (leading == nullptr) {
4465 return nullptr;
4466 }
4467 MemBarNode* mb = leading->as_MemBar();
4468 assert((mb->_kind == LeadingStore && _kind == TrailingStore) ||
4469 (mb->_kind == LeadingLoadStore && _kind == TrailingLoadStore), "bad leading membar");
4470 assert(mb->_pair_idx == _pair_idx, "bad leading membar");
4471 return mb;
4472 }
4473
4474
4475 //===========================InitializeNode====================================
4476 // SUMMARY:
4477 // This node acts as a memory barrier on raw memory, after some raw stores.
4478 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
4479 // The Initialize can 'capture' suitably constrained stores as raw inits.
4480 // It can coalesce related raw stores into larger units (called 'tiles').
4481 // It can avoid zeroing new storage for memory units which have raw inits.
4482 // At macro-expansion, it is marked 'complete', and does not optimize further.
4483 //
4484 // EXAMPLE:
4485 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
4486 // ctl = incoming control; mem* = incoming memory
4487 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
4488 // First allocate uninitialized memory and fill in the header:
4489 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
4490 // ctl := alloc.Control; mem* := alloc.Memory*
4491 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
4492 // Then initialize to zero the non-header parts of the raw memory block:
4493 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
4494 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
4495 // After the initialize node executes, the object is ready for service:
4496 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
4497 // Suppose its body is immediately initialized as {1,2}:
4498 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
4499 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
4500 // mem.SLICE(#short[*]) := store2
4501 //
4502 // DETAILS:
4503 // An InitializeNode collects and isolates object initialization after
4504 // an AllocateNode and before the next possible safepoint. As a
4505 // memory barrier (MemBarNode), it keeps critical stores from drifting
4506 // down past any safepoint or any publication of the allocation.
4507 // Before this barrier, a newly-allocated object may have uninitialized bits.
4508 // After this barrier, it may be treated as a real oop, and GC is allowed.
4509 //
4510 // The semantics of the InitializeNode include an implicit zeroing of
4511 // the new object from object header to the end of the object.
4512 // (The object header and end are determined by the AllocateNode.)
4513 //
4514 // Certain stores may be added as direct inputs to the InitializeNode.
4515 // These stores must update raw memory, and they must be to addresses
4516 // derived from the raw address produced by AllocateNode, and with
4517 // a constant offset. They must be ordered by increasing offset.
4518 // The first one is at in(RawStores), the last at in(req()-1).
4519 // Unlike most memory operations, they are not linked in a chain,
4520 // but are displayed in parallel as users of the rawmem output of
4521 // the allocation.
4522 //
4523 // (See comments in InitializeNode::capture_store, which continue
4524 // the example given above.)
4525 //
4526 // When the associated Allocate is macro-expanded, the InitializeNode
4527 // may be rewritten to optimize collected stores. A ClearArrayNode
4528 // may also be created at that point to represent any required zeroing.
4529 // The InitializeNode is then marked 'complete', prohibiting further
4530 // capturing of nearby memory operations.
4531 //
4532 // During macro-expansion, all captured initializations which store
4533 // constant values of 32 bits or smaller are coalesced (if advantageous)
4534 // into larger 'tiles' 32 or 64 bits. This allows an object to be
4535 // initialized in fewer memory operations. Memory words which are
4536 // covered by neither tiles nor non-constant stores are pre-zeroed
4537 // by explicit stores of zero. (The code shape happens to do all
4538 // zeroing first, then all other stores, with both sequences occurring
4539 // in order of ascending offsets.)
4540 //
4541 // Alternatively, code may be inserted between an AllocateNode and its
4542 // InitializeNode, to perform arbitrary initialization of the new object.
4543 // E.g., the object copying intrinsics insert complex data transfers here.
4544 // The initialization must then be marked as 'complete' disable the
4545 // built-in zeroing semantics and the collection of initializing stores.
4546 //
4547 // While an InitializeNode is incomplete, reads from the memory state
4548 // produced by it are optimizable if they match the control edge and
4549 // new oop address associated with the allocation/initialization.
4550 // They return a stored value (if the offset matches) or else zero.
4551 // A write to the memory state, if it matches control and address,
4552 // and if it is to a constant offset, may be 'captured' by the
4553 // InitializeNode. It is cloned as a raw memory operation and rewired
4554 // inside the initialization, to the raw oop produced by the allocation.
4555 // Operations on addresses which are provably distinct (e.g., to
4556 // other AllocateNodes) are allowed to bypass the initialization.
4557 //
4558 // The effect of all this is to consolidate object initialization
4559 // (both arrays and non-arrays, both piecewise and bulk) into a
4560 // single location, where it can be optimized as a unit.
4561 //
4562 // Only stores with an offset less than TrackedInitializationLimit words
4563 // will be considered for capture by an InitializeNode. This puts a
4564 // reasonable limit on the complexity of optimized initializations.
4565
4566 //---------------------------InitializeNode------------------------------------
4567 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
4568 : MemBarNode(C, adr_type, rawoop),
4569 _is_complete(Incomplete), _does_not_escape(false)
4570 {
4571 init_class_id(Class_Initialize);
4572
4573 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
4574 assert(in(RawAddress) == rawoop, "proper init");
4575 // Note: allocation() can be null, for secondary initialization barriers
4576 }
4577
4578 // Since this node is not matched, it will be processed by the
4579 // register allocator. Declare that there are no constraints
4580 // on the allocation of the RawAddress edge.
4581 const RegMask &InitializeNode::in_RegMask(uint idx) const {
4582 // This edge should be set to top, by the set_complete. But be conservative.
4583 if (idx == InitializeNode::RawAddress)
4584 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
4585 return RegMask::Empty;
4586 }
4587
4588 Node* InitializeNode::memory(uint alias_idx) {
4589 Node* mem = in(Memory);
4590 if (mem->is_MergeMem()) {
4591 return mem->as_MergeMem()->memory_at(alias_idx);
4592 } else {
4593 // incoming raw memory is not split
4594 return mem;
4595 }
4596 }
4597
4598 bool InitializeNode::is_non_zero() {
4599 if (is_complete()) return false;
4600 remove_extra_zeroes();
4601 return (req() > RawStores);
4602 }
4603
4604 void InitializeNode::set_complete(PhaseGVN* phase) {
4605 assert(!is_complete(), "caller responsibility");
4606 _is_complete = Complete;
4607
4608 // After this node is complete, it contains a bunch of
4609 // raw-memory initializations. There is no need for
4610 // it to have anything to do with non-raw memory effects.
4611 // Therefore, tell all non-raw users to re-optimize themselves,
4612 // after skipping the memory effects of this initialization.
4613 PhaseIterGVN* igvn = phase->is_IterGVN();
4614 if (igvn) igvn->add_users_to_worklist(this);
4615 }
4616
4617 // convenience function
4618 // return false if the init contains any stores already
4619 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
4620 InitializeNode* init = initialization();
4621 if (init == nullptr || init->is_complete()) return false;
4622 init->remove_extra_zeroes();
4623 // for now, if this allocation has already collected any inits, bail:
4624 if (init->is_non_zero()) return false;
4625 init->set_complete(phase);
4626 return true;
4627 }
4628
4629 void InitializeNode::remove_extra_zeroes() {
4630 if (req() == RawStores) return;
4631 Node* zmem = zero_memory();
4632 uint fill = RawStores;
4633 for (uint i = fill; i < req(); i++) {
4634 Node* n = in(i);
4635 if (n->is_top() || n == zmem) continue; // skip
4636 if (fill < i) set_req(fill, n); // compact
4637 ++fill;
4638 }
4639 // delete any empty spaces created:
4640 while (fill < req()) {
4641 del_req(fill);
4642 }
4643 }
4644
4645 // Helper for remembering which stores go with which offsets.
4646 intptr_t InitializeNode::get_store_offset(Node* st, PhaseValues* phase) {
4647 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
4648 intptr_t offset = -1;
4649 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
4650 phase, offset);
4651 if (base == nullptr) return -1; // something is dead,
4652 if (offset < 0) return -1; // dead, dead
4653 return offset;
4654 }
4655
4656 // Helper for proving that an initialization expression is
4657 // "simple enough" to be folded into an object initialization.
4658 // Attempts to prove that a store's initial value 'n' can be captured
4659 // within the initialization without creating a vicious cycle, such as:
4660 // { Foo p = new Foo(); p.next = p; }
4661 // True for constants and parameters and small combinations thereof.
4662 bool InitializeNode::detect_init_independence(Node* value, PhaseGVN* phase) {
4663 ResourceMark rm;
4664 Unique_Node_List worklist;
4665 worklist.push(value);
4666
4667 uint complexity_limit = 20;
4668 for (uint j = 0; j < worklist.size(); j++) {
4669 if (j >= complexity_limit) {
4670 return false; // Bail out if processed too many nodes
4671 }
4672
4673 Node* n = worklist.at(j);
4674 if (n == nullptr) continue; // (can this really happen?)
4675 if (n->is_Proj()) n = n->in(0);
4676 if (n == this) return false; // found a cycle
4677 if (n->is_Con()) continue;
4678 if (n->is_Start()) continue; // params, etc., are OK
4679 if (n->is_Root()) continue; // even better
4680
4681 // There cannot be any dependency if 'n' is a CFG node that dominates the current allocation
4682 if (n->is_CFG() && phase->is_dominator(n, allocation())) {
4683 continue;
4684 }
4685
4686 Node* ctl = n->in(0);
4687 if (ctl != nullptr && !ctl->is_top()) {
4688 if (ctl->is_Proj()) ctl = ctl->in(0);
4689 if (ctl == this) return false;
4690
4691 // If we already know that the enclosing memory op is pinned right after
4692 // the init, then any control flow that the store has picked up
4693 // must have preceded the init, or else be equal to the init.
4694 // Even after loop optimizations (which might change control edges)
4695 // a store is never pinned *before* the availability of its inputs.
4696 if (!MemNode::all_controls_dominate(n, this)) {
4697 return false; // failed to prove a good control
4698 }
4699 }
4700
4701 // Check data edges for possible dependencies on 'this'.
4702 for (uint i = 1; i < n->req(); i++) {
4703 Node* m = n->in(i);
4704 if (m == nullptr || m == n || m->is_top()) continue;
4705
4706 // Only process data inputs once
4707 worklist.push(m);
4708 }
4709 }
4710
4711 return true;
4712 }
4713
4714 // Here are all the checks a Store must pass before it can be moved into
4715 // an initialization. Returns zero if a check fails.
4716 // On success, returns the (constant) offset to which the store applies,
4717 // within the initialized memory.
4718 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseGVN* phase, bool can_reshape) {
4719 const int FAIL = 0;
4720 if (st->req() != MemNode::ValueIn + 1)
4721 return FAIL; // an inscrutable StoreNode (card mark?)
4722 Node* ctl = st->in(MemNode::Control);
4723 if (!(ctl != nullptr && ctl->is_Proj() && ctl->in(0) == this))
4724 return FAIL; // must be unconditional after the initialization
4725 Node* mem = st->in(MemNode::Memory);
4726 if (!(mem->is_Proj() && mem->in(0) == this))
4727 return FAIL; // must not be preceded by other stores
4728 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
4729 if ((st->Opcode() == Op_StoreP || st->Opcode() == Op_StoreN) &&
4730 !bs->can_initialize_object(st)) {
4731 return FAIL;
4732 }
4733 Node* adr = st->in(MemNode::Address);
4734 intptr_t offset;
4735 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
4736 if (alloc == nullptr)
4737 return FAIL; // inscrutable address
4738 if (alloc != allocation())
4739 return FAIL; // wrong allocation! (store needs to float up)
4740 int size_in_bytes = st->memory_size();
4741 if ((size_in_bytes != 0) && (offset % size_in_bytes) != 0) {
4742 return FAIL; // mismatched access
4743 }
4744 Node* val = st->in(MemNode::ValueIn);
4745
4746 if (!detect_init_independence(val, phase))
4747 return FAIL; // stored value must be 'simple enough'
4748
4749 // The Store can be captured only if nothing after the allocation
4750 // and before the Store is using the memory location that the store
4751 // overwrites.
4752 bool failed = false;
4753 // If is_complete_with_arraycopy() is true the shape of the graph is
4754 // well defined and is safe so no need for extra checks.
4755 if (!is_complete_with_arraycopy()) {
4756 // We are going to look at each use of the memory state following
4757 // the allocation to make sure nothing reads the memory that the
4758 // Store writes.
4759 const TypePtr* t_adr = phase->type(adr)->isa_ptr();
4760 int alias_idx = phase->C->get_alias_index(t_adr);
4761 ResourceMark rm;
4762 Unique_Node_List mems;
4763 mems.push(mem);
4764 Node* unique_merge = nullptr;
4765 for (uint next = 0; next < mems.size(); ++next) {
4766 Node *m = mems.at(next);
4767 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
4768 Node *n = m->fast_out(j);
4769 if (n->outcnt() == 0) {
4770 continue;
4771 }
4772 if (n == st) {
4773 continue;
4774 } else if (n->in(0) != nullptr && n->in(0) != ctl) {
4775 // If the control of this use is different from the control
4776 // of the Store which is right after the InitializeNode then
4777 // this node cannot be between the InitializeNode and the
4778 // Store.
4779 continue;
4780 } else if (n->is_MergeMem()) {
4781 if (n->as_MergeMem()->memory_at(alias_idx) == m) {
4782 // We can hit a MergeMemNode (that will likely go away
4783 // later) that is a direct use of the memory state
4784 // following the InitializeNode on the same slice as the
4785 // store node that we'd like to capture. We need to check
4786 // the uses of the MergeMemNode.
4787 mems.push(n);
4788 }
4789 } else if (n->is_Mem()) {
4790 Node* other_adr = n->in(MemNode::Address);
4791 if (other_adr == adr) {
4792 failed = true;
4793 break;
4794 } else {
4795 const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr();
4796 if (other_t_adr != nullptr) {
4797 int other_alias_idx = phase->C->get_alias_index(other_t_adr);
4798 if (other_alias_idx == alias_idx) {
4799 // A load from the same memory slice as the store right
4800 // after the InitializeNode. We check the control of the
4801 // object/array that is loaded from. If it's the same as
4802 // the store control then we cannot capture the store.
4803 assert(!n->is_Store(), "2 stores to same slice on same control?");
4804 Node* base = other_adr;
4805 assert(base->is_AddP(), "should be addp but is %s", base->Name());
4806 base = base->in(AddPNode::Base);
4807 if (base != nullptr) {
4808 base = base->uncast();
4809 if (base->is_Proj() && base->in(0) == alloc) {
4810 failed = true;
4811 break;
4812 }
4813 }
4814 }
4815 }
4816 }
4817 } else {
4818 failed = true;
4819 break;
4820 }
4821 }
4822 }
4823 }
4824 if (failed) {
4825 if (!can_reshape) {
4826 // We decided we couldn't capture the store during parsing. We
4827 // should try again during the next IGVN once the graph is
4828 // cleaner.
4829 phase->C->record_for_igvn(st);
4830 }
4831 return FAIL;
4832 }
4833
4834 return offset; // success
4835 }
4836
4837 // Find the captured store in(i) which corresponds to the range
4838 // [start..start+size) in the initialized object.
4839 // If there is one, return its index i. If there isn't, return the
4840 // negative of the index where it should be inserted.
4841 // Return 0 if the queried range overlaps an initialization boundary
4842 // or if dead code is encountered.
4843 // If size_in_bytes is zero, do not bother with overlap checks.
4844 int InitializeNode::captured_store_insertion_point(intptr_t start,
4845 int size_in_bytes,
4846 PhaseValues* phase) {
4847 const int FAIL = 0, MAX_STORE = MAX2(BytesPerLong, (int)MaxVectorSize);
4848
4849 if (is_complete())
4850 return FAIL; // arraycopy got here first; punt
4851
4852 assert(allocation() != nullptr, "must be present");
4853
4854 // no negatives, no header fields:
4855 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
4856
4857 // after a certain size, we bail out on tracking all the stores:
4858 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
4859 if (start >= ti_limit) return FAIL;
4860
4861 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
4862 if (i >= limit) return -(int)i; // not found; here is where to put it
4863
4864 Node* st = in(i);
4865 intptr_t st_off = get_store_offset(st, phase);
4866 if (st_off < 0) {
4867 if (st != zero_memory()) {
4868 return FAIL; // bail out if there is dead garbage
4869 }
4870 } else if (st_off > start) {
4871 // ...we are done, since stores are ordered
4872 if (st_off < start + size_in_bytes) {
4873 return FAIL; // the next store overlaps
4874 }
4875 return -(int)i; // not found; here is where to put it
4876 } else if (st_off < start) {
4877 assert(st->as_Store()->memory_size() <= MAX_STORE, "");
4878 if (size_in_bytes != 0 &&
4879 start < st_off + MAX_STORE &&
4880 start < st_off + st->as_Store()->memory_size()) {
4881 return FAIL; // the previous store overlaps
4882 }
4883 } else {
4884 if (size_in_bytes != 0 &&
4885 st->as_Store()->memory_size() != size_in_bytes) {
4886 return FAIL; // mismatched store size
4887 }
4888 return i;
4889 }
4890
4891 ++i;
4892 }
4893 }
4894
4895 // Look for a captured store which initializes at the offset 'start'
4896 // with the given size. If there is no such store, and no other
4897 // initialization interferes, then return zero_memory (the memory
4898 // projection of the AllocateNode).
4899 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
4900 PhaseValues* phase) {
4901 assert(stores_are_sane(phase), "");
4902 int i = captured_store_insertion_point(start, size_in_bytes, phase);
4903 if (i == 0) {
4904 return nullptr; // something is dead
4905 } else if (i < 0) {
4906 return zero_memory(); // just primordial zero bits here
4907 } else {
4908 Node* st = in(i); // here is the store at this position
4909 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
4910 return st;
4911 }
4912 }
4913
4914 // Create, as a raw pointer, an address within my new object at 'offset'.
4915 Node* InitializeNode::make_raw_address(intptr_t offset,
4916 PhaseGVN* phase) {
4917 Node* addr = in(RawAddress);
4918 if (offset != 0) {
4919 Compile* C = phase->C;
4920 addr = phase->transform( new AddPNode(C->top(), addr,
4921 phase->MakeConX(offset)) );
4922 }
4923 return addr;
4924 }
4925
4926 // Clone the given store, converting it into a raw store
4927 // initializing a field or element of my new object.
4928 // Caller is responsible for retiring the original store,
4929 // with subsume_node or the like.
4930 //
4931 // From the example above InitializeNode::InitializeNode,
4932 // here are the old stores to be captured:
4933 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
4934 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
4935 //
4936 // Here is the changed code; note the extra edges on init:
4937 // alloc = (Allocate ...)
4938 // rawoop = alloc.RawAddress
4939 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
4940 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
4941 // init = (Initialize alloc.Control alloc.Memory rawoop
4942 // rawstore1 rawstore2)
4943 //
4944 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
4945 PhaseGVN* phase, bool can_reshape) {
4946 assert(stores_are_sane(phase), "");
4947
4948 if (start < 0) return nullptr;
4949 assert(can_capture_store(st, phase, can_reshape) == start, "sanity");
4950
4951 Compile* C = phase->C;
4952 int size_in_bytes = st->memory_size();
4953 int i = captured_store_insertion_point(start, size_in_bytes, phase);
4954 if (i == 0) return nullptr; // bail out
4955 Node* prev_mem = nullptr; // raw memory for the captured store
4956 if (i > 0) {
4957 prev_mem = in(i); // there is a pre-existing store under this one
4958 set_req(i, C->top()); // temporarily disconnect it
4959 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
4960 } else {
4961 i = -i; // no pre-existing store
4962 prev_mem = zero_memory(); // a slice of the newly allocated object
4963 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
4964 set_req(--i, C->top()); // reuse this edge; it has been folded away
4965 else
4966 ins_req(i, C->top()); // build a new edge
4967 }
4968 Node* new_st = st->clone();
4969 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
4970 new_st->set_req(MemNode::Control, in(Control));
4971 new_st->set_req(MemNode::Memory, prev_mem);
4972 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
4973 bs->eliminate_gc_barrier_data(new_st);
4974 new_st = phase->transform(new_st);
4975
4976 // At this point, new_st might have swallowed a pre-existing store
4977 // at the same offset, or perhaps new_st might have disappeared,
4978 // if it redundantly stored the same value (or zero to fresh memory).
4979
4980 // In any case, wire it in:
4981 PhaseIterGVN* igvn = phase->is_IterGVN();
4982 if (igvn) {
4983 igvn->rehash_node_delayed(this);
4984 }
4985 set_req(i, new_st);
4986
4987 // The caller may now kill the old guy.
4988 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
4989 assert(check_st == new_st || check_st == nullptr, "must be findable");
4990 assert(!is_complete(), "");
4991 return new_st;
4992 }
4993
4994 static bool store_constant(jlong* tiles, int num_tiles,
4995 intptr_t st_off, int st_size,
4996 jlong con) {
4997 if ((st_off & (st_size-1)) != 0)
4998 return false; // strange store offset (assume size==2**N)
4999 address addr = (address)tiles + st_off;
5000 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
5001 switch (st_size) {
5002 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
5003 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
5004 case sizeof(jint): *(jint*) addr = (jint) con; break;
5005 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
5006 default: return false; // strange store size (detect size!=2**N here)
5007 }
5008 return true; // return success to caller
5009 }
5010
5011 // Coalesce subword constants into int constants and possibly
5012 // into long constants. The goal, if the CPU permits,
5013 // is to initialize the object with a small number of 64-bit tiles.
5014 // Also, convert floating-point constants to bit patterns.
5015 // Non-constants are not relevant to this pass.
5016 //
5017 // In terms of the running example on InitializeNode::InitializeNode
5018 // and InitializeNode::capture_store, here is the transformation
5019 // of rawstore1 and rawstore2 into rawstore12:
5020 // alloc = (Allocate ...)
5021 // rawoop = alloc.RawAddress
5022 // tile12 = 0x00010002
5023 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
5024 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
5025 //
5026 void
5027 InitializeNode::coalesce_subword_stores(intptr_t header_size,
5028 Node* size_in_bytes,
5029 PhaseGVN* phase) {
5030 Compile* C = phase->C;
5031
5032 assert(stores_are_sane(phase), "");
5033 // Note: After this pass, they are not completely sane,
5034 // since there may be some overlaps.
5035
5036 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
5037
5038 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
5039 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
5040 size_limit = MIN2(size_limit, ti_limit);
5041 size_limit = align_up(size_limit, BytesPerLong);
5042 int num_tiles = size_limit / BytesPerLong;
5043
5044 // allocate space for the tile map:
5045 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
5046 jlong tiles_buf[small_len];
5047 Node* nodes_buf[small_len];
5048 jlong inits_buf[small_len];
5049 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
5050 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
5051 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
5052 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
5053 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
5054 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
5055 // tiles: exact bitwise model of all primitive constants
5056 // nodes: last constant-storing node subsumed into the tiles model
5057 // inits: which bytes (in each tile) are touched by any initializations
5058
5059 //// Pass A: Fill in the tile model with any relevant stores.
5060
5061 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
5062 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
5063 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
5064 Node* zmem = zero_memory(); // initially zero memory state
5065 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
5066 Node* st = in(i);
5067 intptr_t st_off = get_store_offset(st, phase);
5068
5069 // Figure out the store's offset and constant value:
5070 if (st_off < header_size) continue; //skip (ignore header)
5071 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
5072 int st_size = st->as_Store()->memory_size();
5073 if (st_off + st_size > size_limit) break;
5074
5075 // Record which bytes are touched, whether by constant or not.
5076 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
5077 continue; // skip (strange store size)
5078
5079 const Type* val = phase->type(st->in(MemNode::ValueIn));
5080 if (!val->singleton()) continue; //skip (non-con store)
5081 BasicType type = val->basic_type();
5082
5083 jlong con = 0;
5084 switch (type) {
5085 case T_INT: con = val->is_int()->get_con(); break;
5086 case T_LONG: con = val->is_long()->get_con(); break;
5087 case T_FLOAT: con = jint_cast(val->getf()); break;
5088 case T_DOUBLE: con = jlong_cast(val->getd()); break;
5089 default: continue; //skip (odd store type)
5090 }
5091
5092 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
5093 st->Opcode() == Op_StoreL) {
5094 continue; // This StoreL is already optimal.
5095 }
5096
5097 // Store down the constant.
5098 store_constant(tiles, num_tiles, st_off, st_size, con);
5099
5100 intptr_t j = st_off >> LogBytesPerLong;
5101
5102 if (type == T_INT && st_size == BytesPerInt
5103 && (st_off & BytesPerInt) == BytesPerInt) {
5104 jlong lcon = tiles[j];
5105 if (!Matcher::isSimpleConstant64(lcon) &&
5106 st->Opcode() == Op_StoreI) {
5107 // This StoreI is already optimal by itself.
5108 jint* intcon = (jint*) &tiles[j];
5109 intcon[1] = 0; // undo the store_constant()
5110
5111 // If the previous store is also optimal by itself, back up and
5112 // undo the action of the previous loop iteration... if we can.
5113 // But if we can't, just let the previous half take care of itself.
5114 st = nodes[j];
5115 st_off -= BytesPerInt;
5116 con = intcon[0];
5117 if (con != 0 && st != nullptr && st->Opcode() == Op_StoreI) {
5118 assert(st_off >= header_size, "still ignoring header");
5119 assert(get_store_offset(st, phase) == st_off, "must be");
5120 assert(in(i-1) == zmem, "must be");
5121 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
5122 assert(con == tcon->is_int()->get_con(), "must be");
5123 // Undo the effects of the previous loop trip, which swallowed st:
5124 intcon[0] = 0; // undo store_constant()
5125 set_req(i-1, st); // undo set_req(i, zmem)
5126 nodes[j] = nullptr; // undo nodes[j] = st
5127 --old_subword; // undo ++old_subword
5128 }
5129 continue; // This StoreI is already optimal.
5130 }
5131 }
5132
5133 // This store is not needed.
5134 set_req(i, zmem);
5135 nodes[j] = st; // record for the moment
5136 if (st_size < BytesPerLong) // something has changed
5137 ++old_subword; // includes int/float, but who's counting...
5138 else ++old_long;
5139 }
5140
5141 if ((old_subword + old_long) == 0)
5142 return; // nothing more to do
5143
5144 //// Pass B: Convert any non-zero tiles into optimal constant stores.
5145 // Be sure to insert them before overlapping non-constant stores.
5146 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
5147 for (int j = 0; j < num_tiles; j++) {
5148 jlong con = tiles[j];
5149 jlong init = inits[j];
5150 if (con == 0) continue;
5151 jint con0, con1; // split the constant, address-wise
5152 jint init0, init1; // split the init map, address-wise
5153 { union { jlong con; jint intcon[2]; } u;
5154 u.con = con;
5155 con0 = u.intcon[0];
5156 con1 = u.intcon[1];
5157 u.con = init;
5158 init0 = u.intcon[0];
5159 init1 = u.intcon[1];
5160 }
5161
5162 Node* old = nodes[j];
5163 assert(old != nullptr, "need the prior store");
5164 intptr_t offset = (j * BytesPerLong);
5165
5166 bool split = !Matcher::isSimpleConstant64(con);
5167
5168 if (offset < header_size) {
5169 assert(offset + BytesPerInt >= header_size, "second int counts");
5170 assert(*(jint*)&tiles[j] == 0, "junk in header");
5171 split = true; // only the second word counts
5172 // Example: int a[] = { 42 ... }
5173 } else if (con0 == 0 && init0 == -1) {
5174 split = true; // first word is covered by full inits
5175 // Example: int a[] = { ... foo(), 42 ... }
5176 } else if (con1 == 0 && init1 == -1) {
5177 split = true; // second word is covered by full inits
5178 // Example: int a[] = { ... 42, foo() ... }
5179 }
5180
5181 // Here's a case where init0 is neither 0 nor -1:
5182 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
5183 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
5184 // In this case the tile is not split; it is (jlong)42.
5185 // The big tile is stored down, and then the foo() value is inserted.
5186 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
5187
5188 Node* ctl = old->in(MemNode::Control);
5189 Node* adr = make_raw_address(offset, phase);
5190 const TypePtr* atp = TypeRawPtr::BOTTOM;
5191
5192 // One or two coalesced stores to plop down.
5193 Node* st[2];
5194 intptr_t off[2];
5195 int nst = 0;
5196 if (!split) {
5197 ++new_long;
5198 off[nst] = offset;
5199 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
5200 phase->longcon(con), T_LONG, MemNode::unordered);
5201 } else {
5202 // Omit either if it is a zero.
5203 if (con0 != 0) {
5204 ++new_int;
5205 off[nst] = offset;
5206 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
5207 phase->intcon(con0), T_INT, MemNode::unordered);
5208 }
5209 if (con1 != 0) {
5210 ++new_int;
5211 offset += BytesPerInt;
5212 adr = make_raw_address(offset, phase);
5213 off[nst] = offset;
5214 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
5215 phase->intcon(con1), T_INT, MemNode::unordered);
5216 }
5217 }
5218
5219 // Insert second store first, then the first before the second.
5220 // Insert each one just before any overlapping non-constant stores.
5221 while (nst > 0) {
5222 Node* st1 = st[--nst];
5223 C->copy_node_notes_to(st1, old);
5224 st1 = phase->transform(st1);
5225 offset = off[nst];
5226 assert(offset >= header_size, "do not smash header");
5227 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
5228 guarantee(ins_idx != 0, "must re-insert constant store");
5229 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
5230 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
5231 set_req(--ins_idx, st1);
5232 else
5233 ins_req(ins_idx, st1);
5234 }
5235 }
5236
5237 if (PrintCompilation && WizardMode)
5238 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
5239 old_subword, old_long, new_int, new_long);
5240 if (C->log() != nullptr)
5241 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
5242 old_subword, old_long, new_int, new_long);
5243
5244 // Clean up any remaining occurrences of zmem:
5245 remove_extra_zeroes();
5246 }
5247
5248 // Explore forward from in(start) to find the first fully initialized
5249 // word, and return its offset. Skip groups of subword stores which
5250 // together initialize full words. If in(start) is itself part of a
5251 // fully initialized word, return the offset of in(start). If there
5252 // are no following full-word stores, or if something is fishy, return
5253 // a negative value.
5254 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
5255 int int_map = 0;
5256 intptr_t int_map_off = 0;
5257 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
5258
5259 for (uint i = start, limit = req(); i < limit; i++) {
5260 Node* st = in(i);
5261
5262 intptr_t st_off = get_store_offset(st, phase);
5263 if (st_off < 0) break; // return conservative answer
5264
5265 int st_size = st->as_Store()->memory_size();
5266 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
5267 return st_off; // we found a complete word init
5268 }
5269
5270 // update the map:
5271
5272 intptr_t this_int_off = align_down(st_off, BytesPerInt);
5273 if (this_int_off != int_map_off) {
5274 // reset the map:
5275 int_map = 0;
5276 int_map_off = this_int_off;
5277 }
5278
5279 int subword_off = st_off - this_int_off;
5280 int_map |= right_n_bits(st_size) << subword_off;
5281 if ((int_map & FULL_MAP) == FULL_MAP) {
5282 return this_int_off; // we found a complete word init
5283 }
5284
5285 // Did this store hit or cross the word boundary?
5286 intptr_t next_int_off = align_down(st_off + st_size, BytesPerInt);
5287 if (next_int_off == this_int_off + BytesPerInt) {
5288 // We passed the current int, without fully initializing it.
5289 int_map_off = next_int_off;
5290 int_map >>= BytesPerInt;
5291 } else if (next_int_off > this_int_off + BytesPerInt) {
5292 // We passed the current and next int.
5293 return this_int_off + BytesPerInt;
5294 }
5295 }
5296
5297 return -1;
5298 }
5299
5300
5301 // Called when the associated AllocateNode is expanded into CFG.
5302 // At this point, we may perform additional optimizations.
5303 // Linearize the stores by ascending offset, to make memory
5304 // activity as coherent as possible.
5305 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
5306 intptr_t header_size,
5307 Node* size_in_bytes,
5308 PhaseIterGVN* phase) {
5309 assert(!is_complete(), "not already complete");
5310 assert(stores_are_sane(phase), "");
5311 assert(allocation() != nullptr, "must be present");
5312
5313 remove_extra_zeroes();
5314
5315 if (ReduceFieldZeroing || ReduceBulkZeroing)
5316 // reduce instruction count for common initialization patterns
5317 coalesce_subword_stores(header_size, size_in_bytes, phase);
5318
5319 Node* zmem = zero_memory(); // initially zero memory state
5320 Node* inits = zmem; // accumulating a linearized chain of inits
5321 #ifdef ASSERT
5322 intptr_t first_offset = allocation()->minimum_header_size();
5323 intptr_t last_init_off = first_offset; // previous init offset
5324 intptr_t last_init_end = first_offset; // previous init offset+size
5325 intptr_t last_tile_end = first_offset; // previous tile offset+size
5326 #endif
5327 intptr_t zeroes_done = header_size;
5328
5329 bool do_zeroing = true; // we might give up if inits are very sparse
5330 int big_init_gaps = 0; // how many large gaps have we seen?
5331
5332 if (UseTLAB && ZeroTLAB) do_zeroing = false;
5333 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
5334
5335 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
5336 Node* st = in(i);
5337 intptr_t st_off = get_store_offset(st, phase);
5338 if (st_off < 0)
5339 break; // unknown junk in the inits
5340 if (st->in(MemNode::Memory) != zmem)
5341 break; // complicated store chains somehow in list
5342
5343 int st_size = st->as_Store()->memory_size();
5344 intptr_t next_init_off = st_off + st_size;
5345
5346 if (do_zeroing && zeroes_done < next_init_off) {
5347 // See if this store needs a zero before it or under it.
5348 intptr_t zeroes_needed = st_off;
5349
5350 if (st_size < BytesPerInt) {
5351 // Look for subword stores which only partially initialize words.
5352 // If we find some, we must lay down some word-level zeroes first,
5353 // underneath the subword stores.
5354 //
5355 // Examples:
5356 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
5357 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
5358 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
5359 //
5360 // Note: coalesce_subword_stores may have already done this,
5361 // if it was prompted by constant non-zero subword initializers.
5362 // But this case can still arise with non-constant stores.
5363
5364 intptr_t next_full_store = find_next_fullword_store(i, phase);
5365
5366 // In the examples above:
5367 // in(i) p q r s x y z
5368 // st_off 12 13 14 15 12 13 14
5369 // st_size 1 1 1 1 1 1 1
5370 // next_full_s. 12 16 16 16 16 16 16
5371 // z's_done 12 16 16 16 12 16 12
5372 // z's_needed 12 16 16 16 16 16 16
5373 // zsize 0 0 0 0 4 0 4
5374 if (next_full_store < 0) {
5375 // Conservative tack: Zero to end of current word.
5376 zeroes_needed = align_up(zeroes_needed, BytesPerInt);
5377 } else {
5378 // Zero to beginning of next fully initialized word.
5379 // Or, don't zero at all, if we are already in that word.
5380 assert(next_full_store >= zeroes_needed, "must go forward");
5381 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
5382 zeroes_needed = next_full_store;
5383 }
5384 }
5385
5386 if (zeroes_needed > zeroes_done) {
5387 intptr_t zsize = zeroes_needed - zeroes_done;
5388 // Do some incremental zeroing on rawmem, in parallel with inits.
5389 zeroes_done = align_down(zeroes_done, BytesPerInt);
5390 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
5391 zeroes_done, zeroes_needed,
5392 phase);
5393 zeroes_done = zeroes_needed;
5394 if (zsize > InitArrayShortSize && ++big_init_gaps > 2)
5395 do_zeroing = false; // leave the hole, next time
5396 }
5397 }
5398
5399 // Collect the store and move on:
5400 phase->replace_input_of(st, MemNode::Memory, inits);
5401 inits = st; // put it on the linearized chain
5402 set_req(i, zmem); // unhook from previous position
5403
5404 if (zeroes_done == st_off)
5405 zeroes_done = next_init_off;
5406
5407 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
5408
5409 #ifdef ASSERT
5410 // Various order invariants. Weaker than stores_are_sane because
5411 // a large constant tile can be filled in by smaller non-constant stores.
5412 assert(st_off >= last_init_off, "inits do not reverse");
5413 last_init_off = st_off;
5414 const Type* val = nullptr;
5415 if (st_size >= BytesPerInt &&
5416 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
5417 (int)val->basic_type() < (int)T_OBJECT) {
5418 assert(st_off >= last_tile_end, "tiles do not overlap");
5419 assert(st_off >= last_init_end, "tiles do not overwrite inits");
5420 last_tile_end = MAX2(last_tile_end, next_init_off);
5421 } else {
5422 intptr_t st_tile_end = align_up(next_init_off, BytesPerLong);
5423 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
5424 assert(st_off >= last_init_end, "inits do not overlap");
5425 last_init_end = next_init_off; // it's a non-tile
5426 }
5427 #endif //ASSERT
5428 }
5429
5430 remove_extra_zeroes(); // clear out all the zmems left over
5431 add_req(inits);
5432
5433 if (!(UseTLAB && ZeroTLAB)) {
5434 // If anything remains to be zeroed, zero it all now.
5435 zeroes_done = align_down(zeroes_done, BytesPerInt);
5436 // if it is the last unused 4 bytes of an instance, forget about it
5437 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
5438 if (zeroes_done + BytesPerLong >= size_limit) {
5439 AllocateNode* alloc = allocation();
5440 assert(alloc != nullptr, "must be present");
5441 if (alloc != nullptr && alloc->Opcode() == Op_Allocate) {
5442 Node* klass_node = alloc->in(AllocateNode::KlassNode);
5443 ciKlass* k = phase->type(klass_node)->is_instklassptr()->instance_klass();
5444 if (zeroes_done == k->layout_helper())
5445 zeroes_done = size_limit;
5446 }
5447 }
5448 if (zeroes_done < size_limit) {
5449 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
5450 zeroes_done, size_in_bytes, phase);
5451 }
5452 }
5453
5454 set_complete(phase);
5455 return rawmem;
5456 }
5457
5458
5459 #ifdef ASSERT
5460 bool InitializeNode::stores_are_sane(PhaseValues* phase) {
5461 if (is_complete())
5462 return true; // stores could be anything at this point
5463 assert(allocation() != nullptr, "must be present");
5464 intptr_t last_off = allocation()->minimum_header_size();
5465 for (uint i = InitializeNode::RawStores; i < req(); i++) {
5466 Node* st = in(i);
5467 intptr_t st_off = get_store_offset(st, phase);
5468 if (st_off < 0) continue; // ignore dead garbage
5469 if (last_off > st_off) {
5470 tty->print_cr("*** bad store offset at %d: %zd > %zd", i, last_off, st_off);
5471 this->dump(2);
5472 assert(false, "ascending store offsets");
5473 return false;
5474 }
5475 last_off = st_off + st->as_Store()->memory_size();
5476 }
5477 return true;
5478 }
5479 #endif //ASSERT
5480
5481
5482
5483
5484 //============================MergeMemNode=====================================
5485 //
5486 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
5487 // contributing store or call operations. Each contributor provides the memory
5488 // state for a particular "alias type" (see Compile::alias_type). For example,
5489 // if a MergeMem has an input X for alias category #6, then any memory reference
5490 // to alias category #6 may use X as its memory state input, as an exact equivalent
5491 // to using the MergeMem as a whole.
5492 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
5493 //
5494 // (Here, the <N> notation gives the index of the relevant adr_type.)
5495 //
5496 // In one special case (and more cases in the future), alias categories overlap.
5497 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
5498 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
5499 // it is exactly equivalent to that state W:
5500 // MergeMem(<Bot>: W) <==> W
5501 //
5502 // Usually, the merge has more than one input. In that case, where inputs
5503 // overlap (i.e., one is Bot), the narrower alias type determines the memory
5504 // state for that type, and the wider alias type (Bot) fills in everywhere else:
5505 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
5506 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
5507 //
5508 // A merge can take a "wide" memory state as one of its narrow inputs.
5509 // This simply means that the merge observes out only the relevant parts of
5510 // the wide input. That is, wide memory states arriving at narrow merge inputs
5511 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
5512 //
5513 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
5514 // and that memory slices "leak through":
5515 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
5516 //
5517 // But, in such a cascade, repeated memory slices can "block the leak":
5518 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
5519 //
5520 // In the last example, Y is not part of the combined memory state of the
5521 // outermost MergeMem. The system must, of course, prevent unschedulable
5522 // memory states from arising, so you can be sure that the state Y is somehow
5523 // a precursor to state Y'.
5524 //
5525 //
5526 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
5527 // of each MergeMemNode array are exactly the numerical alias indexes, including
5528 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
5529 // Compile::alias_type (and kin) produce and manage these indexes.
5530 //
5531 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
5532 // (Note that this provides quick access to the top node inside MergeMem methods,
5533 // without the need to reach out via TLS to Compile::current.)
5534 //
5535 // As a consequence of what was just described, a MergeMem that represents a full
5536 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
5537 // containing all alias categories.
5538 //
5539 // MergeMem nodes never (?) have control inputs, so in(0) is null.
5540 //
5541 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
5542 // a memory state for the alias type <N>, or else the top node, meaning that
5543 // there is no particular input for that alias type. Note that the length of
5544 // a MergeMem is variable, and may be extended at any time to accommodate new
5545 // memory states at larger alias indexes. When merges grow, they are of course
5546 // filled with "top" in the unused in() positions.
5547 //
5548 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
5549 // (Top was chosen because it works smoothly with passes like GCM.)
5550 //
5551 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
5552 // the type of random VM bits like TLS references.) Since it is always the
5553 // first non-Bot memory slice, some low-level loops use it to initialize an
5554 // index variable: for (i = AliasIdxRaw; i < req(); i++).
5555 //
5556 //
5557 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
5558 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
5559 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
5560 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
5561 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
5562 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
5563 //
5564 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
5565 // really that different from the other memory inputs. An abbreviation called
5566 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
5567 //
5568 //
5569 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
5570 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
5571 // that "emerges though" the base memory will be marked as excluding the alias types
5572 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
5573 //
5574 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
5575 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
5576 //
5577 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
5578 // (It is currently unimplemented.) As you can see, the resulting merge is
5579 // actually a disjoint union of memory states, rather than an overlay.
5580 //
5581
5582 //------------------------------MergeMemNode-----------------------------------
5583 Node* MergeMemNode::make_empty_memory() {
5584 Node* empty_memory = (Node*) Compile::current()->top();
5585 assert(empty_memory->is_top(), "correct sentinel identity");
5586 return empty_memory;
5587 }
5588
5589 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
5590 init_class_id(Class_MergeMem);
5591 // all inputs are nullified in Node::Node(int)
5592 // set_input(0, nullptr); // no control input
5593
5594 // Initialize the edges uniformly to top, for starters.
5595 Node* empty_mem = make_empty_memory();
5596 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
5597 init_req(i,empty_mem);
5598 }
5599 assert(empty_memory() == empty_mem, "");
5600
5601 if( new_base != nullptr && new_base->is_MergeMem() ) {
5602 MergeMemNode* mdef = new_base->as_MergeMem();
5603 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
5604 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
5605 mms.set_memory(mms.memory2());
5606 }
5607 assert(base_memory() == mdef->base_memory(), "");
5608 } else {
5609 set_base_memory(new_base);
5610 }
5611 }
5612
5613 // Make a new, untransformed MergeMem with the same base as 'mem'.
5614 // If mem is itself a MergeMem, populate the result with the same edges.
5615 MergeMemNode* MergeMemNode::make(Node* mem) {
5616 return new MergeMemNode(mem);
5617 }
5618
5619 //------------------------------cmp--------------------------------------------
5620 uint MergeMemNode::hash() const { return NO_HASH; }
5621 bool MergeMemNode::cmp( const Node &n ) const {
5622 return (&n == this); // Always fail except on self
5623 }
5624
5625 //------------------------------Identity---------------------------------------
5626 Node* MergeMemNode::Identity(PhaseGVN* phase) {
5627 // Identity if this merge point does not record any interesting memory
5628 // disambiguations.
5629 Node* base_mem = base_memory();
5630 Node* empty_mem = empty_memory();
5631 if (base_mem != empty_mem) { // Memory path is not dead?
5632 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5633 Node* mem = in(i);
5634 if (mem != empty_mem && mem != base_mem) {
5635 return this; // Many memory splits; no change
5636 }
5637 }
5638 }
5639 return base_mem; // No memory splits; ID on the one true input
5640 }
5641
5642 //------------------------------Ideal------------------------------------------
5643 // This method is invoked recursively on chains of MergeMem nodes
5644 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
5645 // Remove chain'd MergeMems
5646 //
5647 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
5648 // relative to the "in(Bot)". Since we are patching both at the same time,
5649 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
5650 // but rewrite each "in(i)" relative to the new "in(Bot)".
5651 Node *progress = nullptr;
5652
5653
5654 Node* old_base = base_memory();
5655 Node* empty_mem = empty_memory();
5656 if (old_base == empty_mem)
5657 return nullptr; // Dead memory path.
5658
5659 MergeMemNode* old_mbase;
5660 if (old_base != nullptr && old_base->is_MergeMem())
5661 old_mbase = old_base->as_MergeMem();
5662 else
5663 old_mbase = nullptr;
5664 Node* new_base = old_base;
5665
5666 // simplify stacked MergeMems in base memory
5667 if (old_mbase) new_base = old_mbase->base_memory();
5668
5669 // the base memory might contribute new slices beyond my req()
5670 if (old_mbase) grow_to_match(old_mbase);
5671
5672 // Note: We do not call verify_sparse on entry, because inputs
5673 // can normalize to the base_memory via subsume_node or similar
5674 // mechanisms. This method repairs that damage.
5675
5676 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
5677
5678 // Look at each slice.
5679 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5680 Node* old_in = in(i);
5681 // calculate the old memory value
5682 Node* old_mem = old_in;
5683 if (old_mem == empty_mem) old_mem = old_base;
5684 assert(old_mem == memory_at(i), "");
5685
5686 // maybe update (reslice) the old memory value
5687
5688 // simplify stacked MergeMems
5689 Node* new_mem = old_mem;
5690 MergeMemNode* old_mmem;
5691 if (old_mem != nullptr && old_mem->is_MergeMem())
5692 old_mmem = old_mem->as_MergeMem();
5693 else
5694 old_mmem = nullptr;
5695 if (old_mmem == this) {
5696 // This can happen if loops break up and safepoints disappear.
5697 // A merge of BotPtr (default) with a RawPtr memory derived from a
5698 // safepoint can be rewritten to a merge of the same BotPtr with
5699 // the BotPtr phi coming into the loop. If that phi disappears
5700 // also, we can end up with a self-loop of the mergemem.
5701 // In general, if loops degenerate and memory effects disappear,
5702 // a mergemem can be left looking at itself. This simply means
5703 // that the mergemem's default should be used, since there is
5704 // no longer any apparent effect on this slice.
5705 // Note: If a memory slice is a MergeMem cycle, it is unreachable
5706 // from start. Update the input to TOP.
5707 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
5708 }
5709 else if (old_mmem != nullptr) {
5710 new_mem = old_mmem->memory_at(i);
5711 }
5712 // else preceding memory was not a MergeMem
5713
5714 // maybe store down a new value
5715 Node* new_in = new_mem;
5716 if (new_in == new_base) new_in = empty_mem;
5717
5718 if (new_in != old_in) {
5719 // Warning: Do not combine this "if" with the previous "if"
5720 // A memory slice might have be be rewritten even if it is semantically
5721 // unchanged, if the base_memory value has changed.
5722 set_req_X(i, new_in, phase);
5723 progress = this; // Report progress
5724 }
5725 }
5726
5727 if (new_base != old_base) {
5728 set_req_X(Compile::AliasIdxBot, new_base, phase);
5729 // Don't use set_base_memory(new_base), because we need to update du.
5730 assert(base_memory() == new_base, "");
5731 progress = this;
5732 }
5733
5734 if( base_memory() == this ) {
5735 // a self cycle indicates this memory path is dead
5736 set_req(Compile::AliasIdxBot, empty_mem);
5737 }
5738
5739 // Resolve external cycles by calling Ideal on a MergeMem base_memory
5740 // Recursion must occur after the self cycle check above
5741 if( base_memory()->is_MergeMem() ) {
5742 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
5743 Node *m = phase->transform(new_mbase); // Rollup any cycles
5744 if( m != nullptr &&
5745 (m->is_top() ||
5746 (m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem)) ) {
5747 // propagate rollup of dead cycle to self
5748 set_req(Compile::AliasIdxBot, empty_mem);
5749 }
5750 }
5751
5752 if( base_memory() == empty_mem ) {
5753 progress = this;
5754 // Cut inputs during Parse phase only.
5755 // During Optimize phase a dead MergeMem node will be subsumed by Top.
5756 if( !can_reshape ) {
5757 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5758 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
5759 }
5760 }
5761 }
5762
5763 if( !progress && base_memory()->is_Phi() && can_reshape ) {
5764 // Check if PhiNode::Ideal's "Split phis through memory merges"
5765 // transform should be attempted. Look for this->phi->this cycle.
5766 uint merge_width = req();
5767 if (merge_width > Compile::AliasIdxRaw) {
5768 PhiNode* phi = base_memory()->as_Phi();
5769 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
5770 if (phi->in(i) == this) {
5771 phase->is_IterGVN()->_worklist.push(phi);
5772 break;
5773 }
5774 }
5775 }
5776 }
5777
5778 assert(progress || verify_sparse(), "please, no dups of base");
5779 return progress;
5780 }
5781
5782 //-------------------------set_base_memory-------------------------------------
5783 void MergeMemNode::set_base_memory(Node *new_base) {
5784 Node* empty_mem = empty_memory();
5785 set_req(Compile::AliasIdxBot, new_base);
5786 assert(memory_at(req()) == new_base, "must set default memory");
5787 // Clear out other occurrences of new_base:
5788 if (new_base != empty_mem) {
5789 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5790 if (in(i) == new_base) set_req(i, empty_mem);
5791 }
5792 }
5793 }
5794
5795 //------------------------------out_RegMask------------------------------------
5796 const RegMask &MergeMemNode::out_RegMask() const {
5797 return RegMask::Empty;
5798 }
5799
5800 //------------------------------dump_spec--------------------------------------
5801 #ifndef PRODUCT
5802 void MergeMemNode::dump_spec(outputStream *st) const {
5803 st->print(" {");
5804 Node* base_mem = base_memory();
5805 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
5806 Node* mem = (in(i) != nullptr) ? memory_at(i) : base_mem;
5807 if (mem == base_mem) { st->print(" -"); continue; }
5808 st->print( " N%d:", mem->_idx );
5809 Compile::current()->get_adr_type(i)->dump_on(st);
5810 }
5811 st->print(" }");
5812 }
5813 #endif // !PRODUCT
5814
5815
5816 #ifdef ASSERT
5817 static bool might_be_same(Node* a, Node* b) {
5818 if (a == b) return true;
5819 if (!(a->is_Phi() || b->is_Phi())) return false;
5820 // phis shift around during optimization
5821 return true; // pretty stupid...
5822 }
5823
5824 // verify a narrow slice (either incoming or outgoing)
5825 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
5826 if (!VerifyAliases) return; // don't bother to verify unless requested
5827 if (VMError::is_error_reported()) return; // muzzle asserts when debugging an error
5828 if (Node::in_dump()) return; // muzzle asserts when printing
5829 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
5830 assert(n != nullptr, "");
5831 // Elide intervening MergeMem's
5832 while (n->is_MergeMem()) {
5833 n = n->as_MergeMem()->memory_at(alias_idx);
5834 }
5835 Compile* C = Compile::current();
5836 const TypePtr* n_adr_type = n->adr_type();
5837 if (n == m->empty_memory()) {
5838 // Implicit copy of base_memory()
5839 } else if (n_adr_type != TypePtr::BOTTOM) {
5840 assert(n_adr_type != nullptr, "new memory must have a well-defined adr_type");
5841 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
5842 } else {
5843 // A few places like make_runtime_call "know" that VM calls are narrow,
5844 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
5845 bool expected_wide_mem = false;
5846 if (n == m->base_memory()) {
5847 expected_wide_mem = true;
5848 } else if (alias_idx == Compile::AliasIdxRaw ||
5849 n == m->memory_at(Compile::AliasIdxRaw)) {
5850 expected_wide_mem = true;
5851 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
5852 // memory can "leak through" calls on channels that
5853 // are write-once. Allow this also.
5854 expected_wide_mem = true;
5855 }
5856 assert(expected_wide_mem, "expected narrow slice replacement");
5857 }
5858 }
5859 #else // !ASSERT
5860 #define verify_memory_slice(m,i,n) (void)(0) // PRODUCT version is no-op
5861 #endif
5862
5863
5864 //-----------------------------memory_at---------------------------------------
5865 Node* MergeMemNode::memory_at(uint alias_idx) const {
5866 assert(alias_idx >= Compile::AliasIdxRaw ||
5867 (alias_idx == Compile::AliasIdxBot && !Compile::current()->do_aliasing()),
5868 "must avoid base_memory and AliasIdxTop");
5869
5870 // Otherwise, it is a narrow slice.
5871 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
5872 if (is_empty_memory(n)) {
5873 // the array is sparse; empty slots are the "top" node
5874 n = base_memory();
5875 assert(Node::in_dump()
5876 || n == nullptr || n->bottom_type() == Type::TOP
5877 || n->adr_type() == nullptr // address is TOP
5878 || n->adr_type() == TypePtr::BOTTOM
5879 || n->adr_type() == TypeRawPtr::BOTTOM
5880 || !Compile::current()->do_aliasing(),
5881 "must be a wide memory");
5882 // do_aliasing == false if we are organizing the memory states manually.
5883 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
5884 } else {
5885 // make sure the stored slice is sane
5886 #ifdef ASSERT
5887 if (VMError::is_error_reported() || Node::in_dump()) {
5888 } else if (might_be_same(n, base_memory())) {
5889 // Give it a pass: It is a mostly harmless repetition of the base.
5890 // This can arise normally from node subsumption during optimization.
5891 } else {
5892 verify_memory_slice(this, alias_idx, n);
5893 }
5894 #endif
5895 }
5896 return n;
5897 }
5898
5899 //---------------------------set_memory_at-------------------------------------
5900 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
5901 verify_memory_slice(this, alias_idx, n);
5902 Node* empty_mem = empty_memory();
5903 if (n == base_memory()) n = empty_mem; // collapse default
5904 uint need_req = alias_idx+1;
5905 if (req() < need_req) {
5906 if (n == empty_mem) return; // already the default, so do not grow me
5907 // grow the sparse array
5908 do {
5909 add_req(empty_mem);
5910 } while (req() < need_req);
5911 }
5912 set_req( alias_idx, n );
5913 }
5914
5915
5916
5917 //--------------------------iteration_setup------------------------------------
5918 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
5919 if (other != nullptr) {
5920 grow_to_match(other);
5921 // invariant: the finite support of mm2 is within mm->req()
5922 #ifdef ASSERT
5923 for (uint i = req(); i < other->req(); i++) {
5924 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
5925 }
5926 #endif
5927 }
5928 // Replace spurious copies of base_memory by top.
5929 Node* base_mem = base_memory();
5930 if (base_mem != nullptr && !base_mem->is_top()) {
5931 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
5932 if (in(i) == base_mem)
5933 set_req(i, empty_memory());
5934 }
5935 }
5936 }
5937
5938 //---------------------------grow_to_match-------------------------------------
5939 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
5940 Node* empty_mem = empty_memory();
5941 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
5942 // look for the finite support of the other memory
5943 for (uint i = other->req(); --i >= req(); ) {
5944 if (other->in(i) != empty_mem) {
5945 uint new_len = i+1;
5946 while (req() < new_len) add_req(empty_mem);
5947 break;
5948 }
5949 }
5950 }
5951
5952 //---------------------------verify_sparse-------------------------------------
5953 #ifndef PRODUCT
5954 bool MergeMemNode::verify_sparse() const {
5955 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
5956 Node* base_mem = base_memory();
5957 // The following can happen in degenerate cases, since empty==top.
5958 if (is_empty_memory(base_mem)) return true;
5959 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5960 assert(in(i) != nullptr, "sane slice");
5961 if (in(i) == base_mem) return false; // should have been the sentinel value!
5962 }
5963 return true;
5964 }
5965
5966 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
5967 Node* n;
5968 n = mm->in(idx);
5969 if (mem == n) return true; // might be empty_memory()
5970 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
5971 if (mem == n) return true;
5972 return false;
5973 }
5974 #endif // !PRODUCT