1 /*
2 * Copyright (c) 1997, 2025, Oracle and/or its affiliates. All rights reserved.
3 * Copyright (c) 2024, Alibaba Group Holding Limited. All rights reserved.
4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
5 *
6 * This code is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License version 2 only, as
8 * published by the Free Software Foundation.
9 *
10 * This code is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13 * version 2 for more details (a copy is included in the LICENSE file that
14 * accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License version
17 * 2 along with this work; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19 *
20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21 * or visit www.oracle.com if you need additional information or have any
22 * questions.
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24 */
25
26 #include "classfile/javaClasses.hpp"
27 #include "compiler/compileLog.hpp"
28 #include "gc/shared/barrierSet.hpp"
29 #include "gc/shared/c2/barrierSetC2.hpp"
30 #include "gc/shared/tlab_globals.hpp"
31 #include "memory/allocation.inline.hpp"
32 #include "memory/resourceArea.hpp"
33 #include "oops/objArrayKlass.hpp"
34 #include "opto/addnode.hpp"
35 #include "opto/arraycopynode.hpp"
36 #include "opto/cfgnode.hpp"
37 #include "opto/regalloc.hpp"
38 #include "opto/compile.hpp"
39 #include "opto/connode.hpp"
40 #include "opto/convertnode.hpp"
41 #include "opto/loopnode.hpp"
42 #include "opto/machnode.hpp"
43 #include "opto/matcher.hpp"
44 #include "opto/memnode.hpp"
45 #include "opto/mempointer.hpp"
46 #include "opto/mulnode.hpp"
47 #include "opto/narrowptrnode.hpp"
48 #include "opto/phaseX.hpp"
49 #include "opto/regmask.hpp"
50 #include "opto/rootnode.hpp"
51 #include "opto/traceMergeStoresTag.hpp"
52 #include "opto/vectornode.hpp"
53 #include "utilities/align.hpp"
54 #include "utilities/copy.hpp"
55 #include "utilities/macros.hpp"
56 #include "utilities/powerOfTwo.hpp"
57 #include "utilities/vmError.hpp"
58
59 // Portions of code courtesy of Clifford Click
60
61 // Optimization - Graph Style
62
63 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st);
64
65 //=============================================================================
66 uint MemNode::size_of() const { return sizeof(*this); }
67
68 const TypePtr *MemNode::adr_type() const {
69 Node* adr = in(Address);
70 if (adr == nullptr) return nullptr; // node is dead
71 const TypePtr* cross_check = nullptr;
72 DEBUG_ONLY(cross_check = _adr_type);
73 return calculate_adr_type(adr->bottom_type(), cross_check);
74 }
75
76 bool MemNode::check_if_adr_maybe_raw(Node* adr) {
77 if (adr != nullptr) {
78 if (adr->bottom_type()->base() == Type::RawPtr || adr->bottom_type()->base() == Type::AnyPtr) {
79 return true;
80 }
81 }
82 return false;
83 }
84
85 #ifndef PRODUCT
86 void MemNode::dump_spec(outputStream *st) const {
87 if (in(Address) == nullptr) return; // node is dead
88 #ifndef ASSERT
89 // fake the missing field
90 const TypePtr* _adr_type = nullptr;
91 if (in(Address) != nullptr)
92 _adr_type = in(Address)->bottom_type()->isa_ptr();
93 #endif
94 dump_adr_type(this, _adr_type, st);
95
96 Compile* C = Compile::current();
97 if (C->alias_type(_adr_type)->is_volatile()) {
98 st->print(" Volatile!");
99 }
100 if (_unaligned_access) {
101 st->print(" unaligned");
102 }
103 if (_mismatched_access) {
104 st->print(" mismatched");
105 }
106 if (_unsafe_access) {
107 st->print(" unsafe");
108 }
109 }
110
111 void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) {
112 st->print(" @");
113 if (adr_type == nullptr) {
114 st->print("null");
115 } else {
116 adr_type->dump_on(st);
117 Compile* C = Compile::current();
118 Compile::AliasType* atp = nullptr;
119 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type);
120 if (atp == nullptr)
121 st->print(", idx=?\?;");
122 else if (atp->index() == Compile::AliasIdxBot)
123 st->print(", idx=Bot;");
124 else if (atp->index() == Compile::AliasIdxTop)
125 st->print(", idx=Top;");
126 else if (atp->index() == Compile::AliasIdxRaw)
127 st->print(", idx=Raw;");
128 else {
129 ciField* field = atp->field();
130 if (field) {
131 st->print(", name=");
132 field->print_name_on(st);
133 }
134 st->print(", idx=%d;", atp->index());
135 }
136 }
137 }
138
139 extern void print_alias_types();
140
141 #endif
142
143 Node *MemNode::optimize_simple_memory_chain(Node *mchain, const TypeOopPtr *t_oop, Node *load, PhaseGVN *phase) {
144 assert((t_oop != nullptr), "sanity");
145 bool is_instance = t_oop->is_known_instance_field();
146 bool is_boxed_value_load = t_oop->is_ptr_to_boxed_value() &&
147 (load != nullptr) && load->is_Load() &&
148 (phase->is_IterGVN() != nullptr);
149 if (!(is_instance || is_boxed_value_load))
150 return mchain; // don't try to optimize non-instance types
151 uint instance_id = t_oop->instance_id();
152 Node *start_mem = phase->C->start()->proj_out_or_null(TypeFunc::Memory);
153 Node *prev = nullptr;
154 Node *result = mchain;
155 while (prev != result) {
156 prev = result;
157 if (result == start_mem)
158 break; // hit one of our sentinels
159 // skip over a call which does not affect this memory slice
160 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {
161 Node *proj_in = result->in(0);
162 if (proj_in->is_Allocate() && proj_in->_idx == instance_id) {
163 break; // hit one of our sentinels
164 } else if (proj_in->is_Call()) {
165 // ArrayCopyNodes processed here as well
166 CallNode *call = proj_in->as_Call();
167 if (!call->may_modify(t_oop, phase)) { // returns false for instances
168 result = call->in(TypeFunc::Memory);
169 }
170 } else if (proj_in->is_Initialize()) {
171 AllocateNode* alloc = proj_in->as_Initialize()->allocation();
172 // Stop if this is the initialization for the object instance which
173 // contains this memory slice, otherwise skip over it.
174 if ((alloc == nullptr) || (alloc->_idx == instance_id)) {
175 break;
176 }
177 if (is_instance) {
178 result = proj_in->in(TypeFunc::Memory);
179 } else if (is_boxed_value_load) {
180 Node* klass = alloc->in(AllocateNode::KlassNode);
181 const TypeKlassPtr* tklass = phase->type(klass)->is_klassptr();
182 if (tklass->klass_is_exact() && !tklass->exact_klass()->equals(t_oop->is_instptr()->exact_klass())) {
183 result = proj_in->in(TypeFunc::Memory); // not related allocation
184 }
185 }
186 } else if (proj_in->is_MemBar()) {
187 ArrayCopyNode* ac = nullptr;
188 if (ArrayCopyNode::may_modify(t_oop, proj_in->as_MemBar(), phase, ac)) {
189 break;
190 }
191 result = proj_in->in(TypeFunc::Memory);
192 } else if (proj_in->is_top()) {
193 break; // dead code
194 } else {
195 assert(false, "unexpected projection");
196 }
197 } else if (result->is_ClearArray()) {
198 if (!is_instance || !ClearArrayNode::step_through(&result, instance_id, phase)) {
199 // Can not bypass initialization of the instance
200 // we are looking for.
201 break;
202 }
203 // Otherwise skip it (the call updated 'result' value).
204 } else if (result->is_MergeMem()) {
205 result = step_through_mergemem(phase, result->as_MergeMem(), t_oop, nullptr, tty);
206 }
207 }
208 return result;
209 }
210
211 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, Node *load, PhaseGVN *phase) {
212 const TypeOopPtr* t_oop = t_adr->isa_oopptr();
213 if (t_oop == nullptr)
214 return mchain; // don't try to optimize non-oop types
215 Node* result = optimize_simple_memory_chain(mchain, t_oop, load, phase);
216 bool is_instance = t_oop->is_known_instance_field();
217 PhaseIterGVN *igvn = phase->is_IterGVN();
218 if (is_instance && igvn != nullptr && result->is_Phi()) {
219 PhiNode *mphi = result->as_Phi();
220 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
221 const TypePtr *t = mphi->adr_type();
222 bool do_split = false;
223 // In the following cases, Load memory input can be further optimized based on
224 // its precise address type
225 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ) {
226 do_split = true;
227 } else if (t->isa_oopptr() && !t->is_oopptr()->is_known_instance()) {
228 const TypeOopPtr* mem_t =
229 t->is_oopptr()->cast_to_exactness(true)
230 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
231 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id());
232 if (t_oop->isa_aryptr()) {
233 mem_t = mem_t->is_aryptr()
234 ->cast_to_stable(t_oop->is_aryptr()->is_stable())
235 ->cast_to_size(t_oop->is_aryptr()->size())
236 ->with_offset(t_oop->is_aryptr()->offset())
237 ->is_aryptr();
238 }
239 do_split = mem_t == t_oop;
240 }
241 if (do_split) {
242 // clone the Phi with our address type
243 result = mphi->split_out_instance(t_adr, igvn);
244 } else {
245 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain");
246 }
247 }
248 return result;
249 }
250
251 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) {
252 uint alias_idx = phase->C->get_alias_index(tp);
253 Node *mem = mmem;
254 #ifdef ASSERT
255 {
256 // Check that current type is consistent with the alias index used during graph construction
257 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
258 bool consistent = adr_check == nullptr || adr_check->empty() ||
259 phase->C->must_alias(adr_check, alias_idx );
260 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
261 if( !consistent && adr_check != nullptr && !adr_check->empty() &&
262 tp->isa_aryptr() && tp->offset() == Type::OffsetBot &&
263 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot &&
264 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() ||
265 adr_check->offset() == oopDesc::klass_offset_in_bytes() ||
266 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) {
267 // don't assert if it is dead code.
268 consistent = true;
269 }
270 if( !consistent ) {
271 st->print("alias_idx==%d, adr_check==", alias_idx);
272 if( adr_check == nullptr ) {
273 st->print("null");
274 } else {
275 adr_check->dump();
276 }
277 st->cr();
278 print_alias_types();
279 assert(consistent, "adr_check must match alias idx");
280 }
281 }
282 #endif
283 // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally
284 // means an array I have not precisely typed yet. Do not do any
285 // alias stuff with it any time soon.
286 const TypeOopPtr *toop = tp->isa_oopptr();
287 if (tp->base() != Type::AnyPtr &&
288 !(toop &&
289 toop->isa_instptr() &&
290 toop->is_instptr()->instance_klass()->is_java_lang_Object() &&
291 toop->offset() == Type::OffsetBot)) {
292 // IGVN _delay_transform may be set to true and if that is the case and mmem
293 // is already a registered node then the validation inside transform will
294 // complain.
295 Node* m = mmem;
296 PhaseIterGVN* igvn = phase->is_IterGVN();
297 if (igvn == nullptr || !igvn->delay_transform()) {
298 // compress paths and change unreachable cycles to TOP
299 // If not, we can update the input infinitely along a MergeMem cycle
300 // Equivalent code in PhiNode::Ideal
301 m = phase->transform(mmem);
302 }
303 // If transformed to a MergeMem, get the desired slice
304 // Otherwise the returned node represents memory for every slice
305 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
306 // Update input if it is progress over what we have now
307 }
308 return mem;
309 }
310
311 //--------------------------Ideal_common---------------------------------------
312 // Look for degenerate control and memory inputs. Bypass MergeMem inputs.
313 // Unhook non-raw memories from complete (macro-expanded) initializations.
314 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
315 // If our control input is a dead region, kill all below the region
316 Node *ctl = in(MemNode::Control);
317 if (ctl && remove_dead_region(phase, can_reshape))
318 return this;
319 ctl = in(MemNode::Control);
320 // Don't bother trying to transform a dead node
321 if (ctl && ctl->is_top()) return NodeSentinel;
322
323 PhaseIterGVN *igvn = phase->is_IterGVN();
324 // Wait if control on the worklist.
325 if (ctl && can_reshape && igvn != nullptr) {
326 Node* bol = nullptr;
327 Node* cmp = nullptr;
328 if (ctl->in(0)->is_If()) {
329 assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity");
330 bol = ctl->in(0)->in(1);
331 if (bol->is_Bool())
332 cmp = ctl->in(0)->in(1)->in(1);
333 }
334 if (igvn->_worklist.member(ctl) ||
335 (bol != nullptr && igvn->_worklist.member(bol)) ||
336 (cmp != nullptr && igvn->_worklist.member(cmp)) ) {
337 // This control path may be dead.
338 // Delay this memory node transformation until the control is processed.
339 igvn->_worklist.push(this);
340 return NodeSentinel; // caller will return null
341 }
342 }
343 // Ignore if memory is dead, or self-loop
344 Node *mem = in(MemNode::Memory);
345 if (phase->type( mem ) == Type::TOP) return NodeSentinel; // caller will return null
346 assert(mem != this, "dead loop in MemNode::Ideal");
347
348 if (can_reshape && igvn != nullptr && igvn->_worklist.member(mem)) {
349 // This memory slice may be dead.
350 // Delay this mem node transformation until the memory is processed.
351 igvn->_worklist.push(this);
352 return NodeSentinel; // caller will return null
353 }
354
355 Node *address = in(MemNode::Address);
356 const Type *t_adr = phase->type(address);
357 if (t_adr == Type::TOP) return NodeSentinel; // caller will return null
358
359 if (can_reshape && is_unsafe_access() && (t_adr == TypePtr::NULL_PTR)) {
360 // Unsafe off-heap access with zero address. Remove access and other control users
361 // to not confuse optimizations and add a HaltNode to fail if this is ever executed.
362 assert(ctl != nullptr, "unsafe accesses should be control dependent");
363 for (DUIterator_Fast imax, i = ctl->fast_outs(imax); i < imax; i++) {
364 Node* u = ctl->fast_out(i);
365 if (u != ctl) {
366 igvn->rehash_node_delayed(u);
367 int nb = u->replace_edge(ctl, phase->C->top(), igvn);
368 --i, imax -= nb;
369 }
370 }
371 Node* frame = igvn->transform(new ParmNode(phase->C->start(), TypeFunc::FramePtr));
372 Node* halt = igvn->transform(new HaltNode(ctl, frame, "unsafe off-heap access with zero address"));
373 phase->C->root()->add_req(halt);
374 return this;
375 }
376
377 if (can_reshape && igvn != nullptr &&
378 (igvn->_worklist.member(address) ||
379 (igvn->_worklist.size() > 0 && t_adr != adr_type())) ) {
380 // The address's base and type may change when the address is processed.
381 // Delay this mem node transformation until the address is processed.
382 igvn->_worklist.push(this);
383 return NodeSentinel; // caller will return null
384 }
385
386 // Do NOT remove or optimize the next lines: ensure a new alias index
387 // is allocated for an oop pointer type before Escape Analysis.
388 // Note: C++ will not remove it since the call has side effect.
389 if (t_adr->isa_oopptr()) {
390 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr());
391 }
392
393 Node* base = nullptr;
394 if (address->is_AddP()) {
395 base = address->in(AddPNode::Base);
396 }
397 if (base != nullptr && phase->type(base)->higher_equal(TypePtr::NULL_PTR) &&
398 !t_adr->isa_rawptr()) {
399 // Note: raw address has TOP base and top->higher_equal(TypePtr::NULL_PTR) is true.
400 // Skip this node optimization if its address has TOP base.
401 return NodeSentinel; // caller will return null
402 }
403
404 // Avoid independent memory operations
405 Node* old_mem = mem;
406
407 // The code which unhooks non-raw memories from complete (macro-expanded)
408 // initializations was removed. After macro-expansion all stores caught
409 // by Initialize node became raw stores and there is no information
410 // which memory slices they modify. So it is unsafe to move any memory
411 // operation above these stores. Also in most cases hooked non-raw memories
412 // were already unhooked by using information from detect_ptr_independence()
413 // and find_previous_store().
414
415 if (mem->is_MergeMem()) {
416 MergeMemNode* mmem = mem->as_MergeMem();
417 const TypePtr *tp = t_adr->is_ptr();
418
419 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
420 }
421
422 if (mem != old_mem) {
423 set_req_X(MemNode::Memory, mem, phase);
424 if (phase->type(mem) == Type::TOP) return NodeSentinel;
425 return this;
426 }
427
428 // let the subclass continue analyzing...
429 return nullptr;
430 }
431
432 // Helper function for proving some simple control dominations.
433 // Attempt to prove that all control inputs of 'dom' dominate 'sub'.
434 // Already assumes that 'dom' is available at 'sub', and that 'sub'
435 // is not a constant (dominated by the method's StartNode).
436 // Used by MemNode::find_previous_store to prove that the
437 // control input of a memory operation predates (dominates)
438 // an allocation it wants to look past.
439 // Returns 'DomResult::Dominate' if all control inputs of 'dom'
440 // dominate 'sub', 'DomResult::NotDominate' if not,
441 // and 'DomResult::EncounteredDeadCode' if we can't decide due to
442 // dead code, but at the end of IGVN, we know the definite result
443 // once the dead code is cleaned up.
444 Node::DomResult MemNode::maybe_all_controls_dominate(Node* dom, Node* sub) {
445 if (dom == nullptr || dom->is_top() || sub == nullptr || sub->is_top()) {
446 return DomResult::EncounteredDeadCode; // Conservative answer for dead code
447 }
448
449 // Check 'dom'. Skip Proj and CatchProj nodes.
450 dom = dom->find_exact_control(dom);
451 if (dom == nullptr || dom->is_top()) {
452 return DomResult::EncounteredDeadCode; // Conservative answer for dead code
453 }
454
455 if (dom == sub) {
456 // For the case when, for example, 'sub' is Initialize and the original
457 // 'dom' is Proj node of the 'sub'.
458 return DomResult::NotDominate;
459 }
460
461 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub) {
462 return DomResult::Dominate;
463 }
464
465 // 'dom' dominates 'sub' if its control edge and control edges
466 // of all its inputs dominate or equal to sub's control edge.
467
468 // Currently 'sub' is either Allocate, Initialize or Start nodes.
469 // Or Region for the check in LoadNode::Ideal();
470 // 'sub' should have sub->in(0) != nullptr.
471 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() ||
472 sub->is_Region() || sub->is_Call(), "expecting only these nodes");
473
474 // Get control edge of 'sub'.
475 Node* orig_sub = sub;
476 sub = sub->find_exact_control(sub->in(0));
477 if (sub == nullptr || sub->is_top()) {
478 return DomResult::EncounteredDeadCode; // Conservative answer for dead code
479 }
480
481 assert(sub->is_CFG(), "expecting control");
482
483 if (sub == dom) {
484 return DomResult::Dominate;
485 }
486
487 if (sub->is_Start() || sub->is_Root()) {
488 return DomResult::NotDominate;
489 }
490
491 {
492 // Check all control edges of 'dom'.
493
494 ResourceMark rm;
495 Node_List nlist;
496 Unique_Node_List dom_list;
497
498 dom_list.push(dom);
499 bool only_dominating_controls = false;
500
501 for (uint next = 0; next < dom_list.size(); next++) {
502 Node* n = dom_list.at(next);
503 if (n == orig_sub) {
504 return DomResult::NotDominate; // One of dom's inputs dominated by sub.
505 }
506 if (!n->is_CFG() && n->pinned()) {
507 // Check only own control edge for pinned non-control nodes.
508 n = n->find_exact_control(n->in(0));
509 if (n == nullptr || n->is_top()) {
510 return DomResult::EncounteredDeadCode; // Conservative answer for dead code
511 }
512 assert(n->is_CFG(), "expecting control");
513 dom_list.push(n);
514 } else if (n->is_Con() || n->is_Start() || n->is_Root()) {
515 only_dominating_controls = true;
516 } else if (n->is_CFG()) {
517 DomResult dom_result = n->dominates(sub, nlist);
518 if (dom_result == DomResult::Dominate) {
519 only_dominating_controls = true;
520 } else {
521 return dom_result;
522 }
523 } else {
524 // First, own control edge.
525 Node* m = n->find_exact_control(n->in(0));
526 if (m != nullptr) {
527 if (m->is_top()) {
528 return DomResult::EncounteredDeadCode; // Conservative answer for dead code
529 }
530 dom_list.push(m);
531 }
532 // Now, the rest of edges.
533 uint cnt = n->req();
534 for (uint i = 1; i < cnt; i++) {
535 m = n->find_exact_control(n->in(i));
536 if (m == nullptr || m->is_top()) {
537 continue;
538 }
539 dom_list.push(m);
540 }
541 }
542 }
543 return only_dominating_controls ? DomResult::Dominate : DomResult::NotDominate;
544 }
545 }
546
547 //---------------------detect_ptr_independence---------------------------------
548 // Used by MemNode::find_previous_store to prove that two base
549 // pointers are never equal.
550 // The pointers are accompanied by their associated allocations,
551 // if any, which have been previously discovered by the caller.
552 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
553 Node* p2, AllocateNode* a2,
554 PhaseTransform* phase) {
555 // Attempt to prove that these two pointers cannot be aliased.
556 // They may both manifestly be allocations, and they should differ.
557 // Or, if they are not both allocations, they can be distinct constants.
558 // Otherwise, one is an allocation and the other a pre-existing value.
559 if (a1 == nullptr && a2 == nullptr) { // neither an allocation
560 return (p1 != p2) && p1->is_Con() && p2->is_Con();
561 } else if (a1 != nullptr && a2 != nullptr) { // both allocations
562 return (a1 != a2);
563 } else if (a1 != nullptr) { // one allocation a1
564 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.)
565 return all_controls_dominate(p2, a1);
566 } else { //(a2 != null) // one allocation a2
567 return all_controls_dominate(p1, a2);
568 }
569 return false;
570 }
571
572
573 // Find an arraycopy ac that produces the memory state represented by parameter mem.
574 // Return ac if
575 // (a) can_see_stored_value=true and ac must have set the value for this load or if
576 // (b) can_see_stored_value=false and ac could have set the value for this load or if
577 // (c) can_see_stored_value=false and ac cannot have set the value for this load.
578 // In case (c) change the parameter mem to the memory input of ac to skip it
579 // when searching stored value.
580 // Otherwise return null.
581 Node* LoadNode::find_previous_arraycopy(PhaseValues* phase, Node* ld_alloc, Node*& mem, bool can_see_stored_value) const {
582 ArrayCopyNode* ac = find_array_copy_clone(ld_alloc, mem);
583 if (ac != nullptr) {
584 Node* ld_addp = in(MemNode::Address);
585 Node* src = ac->in(ArrayCopyNode::Src);
586 const TypeAryPtr* ary_t = phase->type(src)->isa_aryptr();
587
588 // This is a load from a cloned array. The corresponding arraycopy ac must
589 // have set the value for the load and we can return ac but only if the load
590 // is known to be within bounds. This is checked below.
591 if (ary_t != nullptr && ld_addp->is_AddP()) {
592 Node* ld_offs = ld_addp->in(AddPNode::Offset);
593 BasicType ary_elem = ary_t->elem()->array_element_basic_type();
594 jlong header = arrayOopDesc::base_offset_in_bytes(ary_elem);
595 jlong elemsize = type2aelembytes(ary_elem);
596
597 const TypeX* ld_offs_t = phase->type(ld_offs)->isa_intptr_t();
598 const TypeInt* sizetype = ary_t->size();
599
600 if (ld_offs_t->_lo >= header && ld_offs_t->_hi < (sizetype->_lo * elemsize + header)) {
601 // The load is known to be within bounds. It receives its value from ac.
602 return ac;
603 }
604 // The load is known to be out-of-bounds.
605 }
606 // The load could be out-of-bounds. It must not be hoisted but must remain
607 // dependent on the runtime range check. This is achieved by returning null.
608 } else if (mem->is_Proj() && mem->in(0) != nullptr && mem->in(0)->is_ArrayCopy()) {
609 ArrayCopyNode* ac = mem->in(0)->as_ArrayCopy();
610
611 if (ac->is_arraycopy_validated() ||
612 ac->is_copyof_validated() ||
613 ac->is_copyofrange_validated()) {
614 Node* ld_addp = in(MemNode::Address);
615 if (ld_addp->is_AddP()) {
616 Node* ld_base = ld_addp->in(AddPNode::Address);
617 Node* ld_offs = ld_addp->in(AddPNode::Offset);
618
619 Node* dest = ac->in(ArrayCopyNode::Dest);
620
621 if (dest == ld_base) {
622 const TypeX* ld_offs_t = phase->type(ld_offs)->isa_intptr_t();
623 assert(!ld_offs_t->empty(), "dead reference should be checked already");
624 // Take into account vector or unsafe access size
625 jlong ld_size_in_bytes = (jlong)memory_size();
626 jlong offset_hi = ld_offs_t->_hi + ld_size_in_bytes - 1;
627 offset_hi = MIN2(offset_hi, (jlong)(TypeX::MAX->_hi)); // Take care for overflow in 32-bit VM
628 if (ac->modifies(ld_offs_t->_lo, (intptr_t)offset_hi, phase, can_see_stored_value)) {
629 return ac;
630 }
631 if (!can_see_stored_value) {
632 mem = ac->in(TypeFunc::Memory);
633 return ac;
634 }
635 }
636 }
637 }
638 }
639 return nullptr;
640 }
641
642 ArrayCopyNode* MemNode::find_array_copy_clone(Node* ld_alloc, Node* mem) const {
643 if (mem->is_Proj() && mem->in(0) != nullptr && (mem->in(0)->Opcode() == Op_MemBarStoreStore ||
644 mem->in(0)->Opcode() == Op_MemBarCPUOrder)) {
645 if (ld_alloc != nullptr) {
646 // Check if there is an array copy for a clone
647 Node* mb = mem->in(0);
648 ArrayCopyNode* ac = nullptr;
649 if (mb->in(0) != nullptr && mb->in(0)->is_Proj() &&
650 mb->in(0)->in(0) != nullptr && mb->in(0)->in(0)->is_ArrayCopy()) {
651 ac = mb->in(0)->in(0)->as_ArrayCopy();
652 } else {
653 // Step over GC barrier when ReduceInitialCardMarks is disabled
654 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
655 Node* control_proj_ac = bs->step_over_gc_barrier(mb->in(0));
656
657 if (control_proj_ac->is_Proj() && control_proj_ac->in(0)->is_ArrayCopy()) {
658 ac = control_proj_ac->in(0)->as_ArrayCopy();
659 }
660 }
661
662 if (ac != nullptr && ac->is_clonebasic()) {
663 AllocateNode* alloc = AllocateNode::Ideal_allocation(ac->in(ArrayCopyNode::Dest));
664 if (alloc != nullptr && alloc == ld_alloc) {
665 return ac;
666 }
667 }
668 }
669 }
670 return nullptr;
671 }
672
673 // The logic for reordering loads and stores uses four steps:
674 // (a) Walk carefully past stores and initializations which we
675 // can prove are independent of this load.
676 // (b) Observe that the next memory state makes an exact match
677 // with self (load or store), and locate the relevant store.
678 // (c) Ensure that, if we were to wire self directly to the store,
679 // the optimizer would fold it up somehow.
680 // (d) Do the rewiring, and return, depending on some other part of
681 // the optimizer to fold up the load.
682 // This routine handles steps (a) and (b). Steps (c) and (d) are
683 // specific to loads and stores, so they are handled by the callers.
684 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.)
685 //
686 Node* MemNode::find_previous_store(PhaseValues* phase) {
687 Node* ctrl = in(MemNode::Control);
688 Node* adr = in(MemNode::Address);
689 intptr_t offset = 0;
690 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
691 AllocateNode* alloc = AllocateNode::Ideal_allocation(base);
692
693 if (offset == Type::OffsetBot)
694 return nullptr; // cannot unalias unless there are precise offsets
695
696 const bool adr_maybe_raw = check_if_adr_maybe_raw(adr);
697 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr();
698
699 intptr_t size_in_bytes = memory_size();
700
701 Node* mem = in(MemNode::Memory); // start searching here...
702
703 int cnt = 50; // Cycle limiter
704 for (;;) { // While we can dance past unrelated stores...
705 if (--cnt < 0) break; // Caught in cycle or a complicated dance?
706
707 Node* prev = mem;
708 if (mem->is_Store()) {
709 Node* st_adr = mem->in(MemNode::Address);
710 intptr_t st_offset = 0;
711 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
712 if (st_base == nullptr)
713 break; // inscrutable pointer
714
715 // For raw accesses it's not enough to prove that constant offsets don't intersect.
716 // We need the bases to be the equal in order for the offset check to make sense.
717 if ((adr_maybe_raw || check_if_adr_maybe_raw(st_adr)) && st_base != base) {
718 break;
719 }
720
721 if (st_offset != offset && st_offset != Type::OffsetBot) {
722 const int MAX_STORE = MAX2(BytesPerLong, (int)MaxVectorSize);
723 assert(mem->as_Store()->memory_size() <= MAX_STORE, "");
724 if (st_offset >= offset + size_in_bytes ||
725 st_offset <= offset - MAX_STORE ||
726 st_offset <= offset - mem->as_Store()->memory_size()) {
727 // Success: The offsets are provably independent.
728 // (You may ask, why not just test st_offset != offset and be done?
729 // The answer is that stores of different sizes can co-exist
730 // in the same sequence of RawMem effects. We sometimes initialize
731 // a whole 'tile' of array elements with a single jint or jlong.)
732 mem = mem->in(MemNode::Memory);
733 continue; // (a) advance through independent store memory
734 }
735 }
736 if (st_base != base &&
737 detect_ptr_independence(base, alloc,
738 st_base,
739 AllocateNode::Ideal_allocation(st_base),
740 phase)) {
741 // Success: The bases are provably independent.
742 mem = mem->in(MemNode::Memory);
743 continue; // (a) advance through independent store memory
744 }
745
746 // (b) At this point, if the bases or offsets do not agree, we lose,
747 // since we have not managed to prove 'this' and 'mem' independent.
748 if (st_base == base && st_offset == offset) {
749 return mem; // let caller handle steps (c), (d)
750 }
751
752 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
753 InitializeNode* st_init = mem->in(0)->as_Initialize();
754 AllocateNode* st_alloc = st_init->allocation();
755 if (st_alloc == nullptr) {
756 break; // something degenerated
757 }
758 bool known_identical = false;
759 bool known_independent = false;
760 if (alloc == st_alloc) {
761 known_identical = true;
762 } else if (alloc != nullptr) {
763 known_independent = true;
764 } else if (all_controls_dominate(this, st_alloc)) {
765 known_independent = true;
766 }
767
768 if (known_independent) {
769 // The bases are provably independent: Either they are
770 // manifestly distinct allocations, or else the control
771 // of this load dominates the store's allocation.
772 int alias_idx = phase->C->get_alias_index(adr_type());
773 if (alias_idx == Compile::AliasIdxRaw) {
774 mem = st_alloc->in(TypeFunc::Memory);
775 } else {
776 mem = st_init->memory(alias_idx);
777 }
778 continue; // (a) advance through independent store memory
779 }
780
781 // (b) at this point, if we are not looking at a store initializing
782 // the same allocation we are loading from, we lose.
783 if (known_identical) {
784 // From caller, can_see_stored_value will consult find_captured_store.
785 return mem; // let caller handle steps (c), (d)
786 }
787
788 } else if (find_previous_arraycopy(phase, alloc, mem, false) != nullptr) {
789 if (prev != mem) {
790 // Found an arraycopy but it doesn't affect that load
791 continue;
792 }
793 // Found an arraycopy that may affect that load
794 return mem;
795 } else if (addr_t != nullptr && addr_t->is_known_instance_field()) {
796 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
797 if (mem->is_Proj() && mem->in(0)->is_Call()) {
798 // ArrayCopyNodes processed here as well.
799 CallNode *call = mem->in(0)->as_Call();
800 if (!call->may_modify(addr_t, phase)) {
801 mem = call->in(TypeFunc::Memory);
802 continue; // (a) advance through independent call memory
803 }
804 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) {
805 ArrayCopyNode* ac = nullptr;
806 if (ArrayCopyNode::may_modify(addr_t, mem->in(0)->as_MemBar(), phase, ac)) {
807 break;
808 }
809 mem = mem->in(0)->in(TypeFunc::Memory);
810 continue; // (a) advance through independent MemBar memory
811 } else if (mem->is_ClearArray()) {
812 if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) {
813 // (the call updated 'mem' value)
814 continue; // (a) advance through independent allocation memory
815 } else {
816 // Can not bypass initialization of the instance
817 // we are looking for.
818 return mem;
819 }
820 } else if (mem->is_MergeMem()) {
821 int alias_idx = phase->C->get_alias_index(adr_type());
822 mem = mem->as_MergeMem()->memory_at(alias_idx);
823 continue; // (a) advance through independent MergeMem memory
824 }
825 }
826
827 // Unless there is an explicit 'continue', we must bail out here,
828 // because 'mem' is an inscrutable memory state (e.g., a call).
829 break;
830 }
831
832 return nullptr; // bail out
833 }
834
835 //----------------------calculate_adr_type-------------------------------------
836 // Helper function. Notices when the given type of address hits top or bottom.
837 // Also, asserts a cross-check of the type against the expected address type.
838 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
839 if (t == Type::TOP) return nullptr; // does not touch memory any more?
840 #ifdef ASSERT
841 if (!VerifyAliases || VMError::is_error_reported() || Node::in_dump()) cross_check = nullptr;
842 #endif
843 const TypePtr* tp = t->isa_ptr();
844 if (tp == nullptr) {
845 assert(cross_check == nullptr || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
846 return TypePtr::BOTTOM; // touches lots of memory
847 } else {
848 #ifdef ASSERT
849 // %%%% [phh] We don't check the alias index if cross_check is
850 // TypeRawPtr::BOTTOM. Needs to be investigated.
851 if (cross_check != nullptr &&
852 cross_check != TypePtr::BOTTOM &&
853 cross_check != TypeRawPtr::BOTTOM) {
854 // Recheck the alias index, to see if it has changed (due to a bug).
855 Compile* C = Compile::current();
856 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
857 "must stay in the original alias category");
858 // The type of the address must be contained in the adr_type,
859 // disregarding "null"-ness.
860 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
861 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
862 assert(cross_check->meet(tp_notnull) == cross_check->remove_speculative(),
863 "real address must not escape from expected memory type");
864 }
865 #endif
866 return tp;
867 }
868 }
869
870 uint8_t MemNode::barrier_data(const Node* n) {
871 if (n->is_LoadStore()) {
872 return n->as_LoadStore()->barrier_data();
873 } else if (n->is_Mem()) {
874 return n->as_Mem()->barrier_data();
875 }
876 return 0;
877 }
878
879 //=============================================================================
880 // Should LoadNode::Ideal() attempt to remove control edges?
881 bool LoadNode::can_remove_control() const {
882 return !has_pinned_control_dependency();
883 }
884 uint LoadNode::size_of() const { return sizeof(*this); }
885 bool LoadNode::cmp(const Node &n) const {
886 LoadNode& load = (LoadNode &)n;
887 return Type::equals(_type, load._type) &&
888 _control_dependency == load._control_dependency &&
889 _mo == load._mo;
890 }
891 const Type *LoadNode::bottom_type() const { return _type; }
892 uint LoadNode::ideal_reg() const {
893 return _type->ideal_reg();
894 }
895
896 #ifndef PRODUCT
897 void LoadNode::dump_spec(outputStream *st) const {
898 MemNode::dump_spec(st);
899 if( !Verbose && !WizardMode ) {
900 // standard dump does this in Verbose and WizardMode
901 st->print(" #"); _type->dump_on(st);
902 }
903 if (!depends_only_on_test()) {
904 st->print(" (does not depend only on test, ");
905 if (control_dependency() == UnknownControl) {
906 st->print("unknown control");
907 } else if (control_dependency() == Pinned) {
908 st->print("pinned");
909 } else if (adr_type() == TypeRawPtr::BOTTOM) {
910 st->print("raw access");
911 } else {
912 st->print("unknown reason");
913 }
914 st->print(")");
915 }
916 }
917 #endif
918
919 #ifdef ASSERT
920 //----------------------------is_immutable_value-------------------------------
921 // Helper function to allow a raw load without control edge for some cases
922 bool LoadNode::is_immutable_value(Node* adr) {
923 if (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() &&
924 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal) {
925
926 jlong offset = adr->in(AddPNode::Offset)->find_intptr_t_con(-1);
927 int offsets[] = {
928 in_bytes(JavaThread::osthread_offset()),
929 in_bytes(JavaThread::threadObj_offset()),
930 in_bytes(JavaThread::vthread_offset()),
931 in_bytes(JavaThread::scopedValueCache_offset()),
932 };
933
934 for (size_t i = 0; i < sizeof offsets / sizeof offsets[0]; i++) {
935 if (offset == offsets[i]) {
936 return true;
937 }
938 }
939 }
940
941 return false;
942 }
943 #endif
944
945 //----------------------------LoadNode::make-----------------------------------
946 // Polymorphic factory method:
947 Node* LoadNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, BasicType bt, MemOrd mo,
948 ControlDependency control_dependency, bool require_atomic_access, bool unaligned, bool mismatched, bool unsafe, uint8_t barrier_data) {
949 Compile* C = gvn.C;
950
951 // sanity check the alias category against the created node type
952 assert(!(adr_type->isa_oopptr() &&
953 adr_type->offset() == oopDesc::klass_offset_in_bytes()),
954 "use LoadKlassNode instead");
955 assert(!(adr_type->isa_aryptr() &&
956 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
957 "use LoadRangeNode instead");
958 // Check control edge of raw loads
959 assert( ctl != nullptr || C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
960 // oop will be recorded in oop map if load crosses safepoint
961 rt->isa_oopptr() || is_immutable_value(adr),
962 "raw memory operations should have control edge");
963 LoadNode* load = nullptr;
964 switch (bt) {
965 case T_BOOLEAN: load = new LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
966 case T_BYTE: load = new LoadBNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
967 case T_INT: load = new LoadINode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
968 case T_CHAR: load = new LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
969 case T_SHORT: load = new LoadSNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
970 case T_LONG: load = new LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency, require_atomic_access); break;
971 case T_FLOAT: load = new LoadFNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); break;
972 case T_DOUBLE: load = new LoadDNode (ctl, mem, adr, adr_type, rt, mo, control_dependency, require_atomic_access); break;
973 case T_ADDRESS: load = new LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency); break;
974 case T_OBJECT:
975 case T_NARROWOOP:
976 #ifdef _LP64
977 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
978 load = new LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo, control_dependency);
979 } else
980 #endif
981 {
982 assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop");
983 load = new LoadPNode(ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency);
984 }
985 break;
986 default:
987 ShouldNotReachHere();
988 break;
989 }
990 assert(load != nullptr, "LoadNode should have been created");
991 if (unaligned) {
992 load->set_unaligned_access();
993 }
994 if (mismatched) {
995 load->set_mismatched_access();
996 }
997 if (unsafe) {
998 load->set_unsafe_access();
999 }
1000 load->set_barrier_data(barrier_data);
1001 if (load->Opcode() == Op_LoadN) {
1002 Node* ld = gvn.transform(load);
1003 return new DecodeNNode(ld, ld->bottom_type()->make_ptr());
1004 }
1005
1006 return load;
1007 }
1008
1009 //------------------------------hash-------------------------------------------
1010 uint LoadNode::hash() const {
1011 // unroll addition of interesting fields
1012 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
1013 }
1014
1015 static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) {
1016 if ((atp != nullptr) && (atp->index() >= Compile::AliasIdxRaw)) {
1017 bool non_volatile = (atp->field() != nullptr) && !atp->field()->is_volatile();
1018 bool is_stable_ary = FoldStableValues &&
1019 (tp != nullptr) && (tp->isa_aryptr() != nullptr) &&
1020 tp->isa_aryptr()->is_stable();
1021
1022 return (eliminate_boxing && non_volatile) || is_stable_ary;
1023 }
1024
1025 return false;
1026 }
1027
1028 LoadNode* LoadNode::pin_array_access_node() const {
1029 const TypePtr* adr_type = this->adr_type();
1030 if (adr_type != nullptr && adr_type->isa_aryptr()) {
1031 return clone_pinned();
1032 }
1033 return nullptr;
1034 }
1035
1036 // Is the value loaded previously stored by an arraycopy? If so return
1037 // a load node that reads from the source array so we may be able to
1038 // optimize out the ArrayCopy node later.
1039 Node* LoadNode::can_see_arraycopy_value(Node* st, PhaseGVN* phase) const {
1040 Node* ld_adr = in(MemNode::Address);
1041 intptr_t ld_off = 0;
1042 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
1043 Node* ac = find_previous_arraycopy(phase, ld_alloc, st, true);
1044 if (ac != nullptr) {
1045 assert(ac->is_ArrayCopy(), "what kind of node can this be?");
1046
1047 Node* mem = ac->in(TypeFunc::Memory);
1048 Node* ctl = ac->in(0);
1049 Node* src = ac->in(ArrayCopyNode::Src);
1050
1051 if (!ac->as_ArrayCopy()->is_clonebasic() && !phase->type(src)->isa_aryptr()) {
1052 return nullptr;
1053 }
1054
1055 // load depends on the tests that validate the arraycopy
1056 LoadNode* ld = clone_pinned();
1057 Node* addp = in(MemNode::Address)->clone();
1058 if (ac->as_ArrayCopy()->is_clonebasic()) {
1059 assert(ld_alloc != nullptr, "need an alloc");
1060 assert(addp->is_AddP(), "address must be addp");
1061 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1062 assert(bs->step_over_gc_barrier(addp->in(AddPNode::Base)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)), "strange pattern");
1063 assert(bs->step_over_gc_barrier(addp->in(AddPNode::Address)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)), "strange pattern");
1064 addp->set_req(AddPNode::Base, src);
1065 addp->set_req(AddPNode::Address, src);
1066 } else {
1067 assert(ac->as_ArrayCopy()->is_arraycopy_validated() ||
1068 ac->as_ArrayCopy()->is_copyof_validated() ||
1069 ac->as_ArrayCopy()->is_copyofrange_validated(), "only supported cases");
1070 assert(addp->in(AddPNode::Base) == addp->in(AddPNode::Address), "should be");
1071 addp->set_req(AddPNode::Base, src);
1072 addp->set_req(AddPNode::Address, src);
1073
1074 const TypeAryPtr* ary_t = phase->type(in(MemNode::Address))->isa_aryptr();
1075 BasicType ary_elem = ary_t->isa_aryptr()->elem()->array_element_basic_type();
1076 if (is_reference_type(ary_elem, true)) ary_elem = T_OBJECT;
1077
1078 uint header = arrayOopDesc::base_offset_in_bytes(ary_elem);
1079 uint shift = exact_log2(type2aelembytes(ary_elem));
1080
1081 Node* diff = phase->transform(new SubINode(ac->in(ArrayCopyNode::SrcPos), ac->in(ArrayCopyNode::DestPos)));
1082 #ifdef _LP64
1083 diff = phase->transform(new ConvI2LNode(diff));
1084 #endif
1085 diff = phase->transform(new LShiftXNode(diff, phase->intcon(shift)));
1086
1087 Node* offset = phase->transform(new AddXNode(addp->in(AddPNode::Offset), diff));
1088 addp->set_req(AddPNode::Offset, offset);
1089 }
1090 addp = phase->transform(addp);
1091 #ifdef ASSERT
1092 const TypePtr* adr_type = phase->type(addp)->is_ptr();
1093 ld->_adr_type = adr_type;
1094 #endif
1095 ld->set_req(MemNode::Address, addp);
1096 ld->set_req(0, ctl);
1097 ld->set_req(MemNode::Memory, mem);
1098 return ld;
1099 }
1100 return nullptr;
1101 }
1102
1103
1104 //---------------------------can_see_stored_value------------------------------
1105 // This routine exists to make sure this set of tests is done the same
1106 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
1107 // will change the graph shape in a way which makes memory alive twice at the
1108 // same time (uses the Oracle model of aliasing), then some
1109 // LoadXNode::Identity will fold things back to the equivalence-class model
1110 // of aliasing.
1111 Node* MemNode::can_see_stored_value(Node* st, PhaseValues* phase) const {
1112 Node* ld_adr = in(MemNode::Address);
1113 intptr_t ld_off = 0;
1114 Node* ld_base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ld_off);
1115 Node* ld_alloc = AllocateNode::Ideal_allocation(ld_base);
1116 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
1117 Compile::AliasType* atp = (tp != nullptr) ? phase->C->alias_type(tp) : nullptr;
1118 // This is more general than load from boxing objects.
1119 if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) {
1120 uint alias_idx = atp->index();
1121 Node* result = nullptr;
1122 Node* current = st;
1123 // Skip through chains of MemBarNodes checking the MergeMems for
1124 // new states for the slice of this load. Stop once any other
1125 // kind of node is encountered. Loads from final memory can skip
1126 // through any kind of MemBar but normal loads shouldn't skip
1127 // through MemBarAcquire since the could allow them to move out of
1128 // a synchronized region. It is not safe to step over MemBarCPUOrder,
1129 // because alias info above them may be inaccurate (e.g., due to
1130 // mixed/mismatched unsafe accesses).
1131 bool is_final_mem = !atp->is_rewritable();
1132 while (current->is_Proj()) {
1133 int opc = current->in(0)->Opcode();
1134 if ((is_final_mem && (opc == Op_MemBarAcquire ||
1135 opc == Op_MemBarAcquireLock ||
1136 opc == Op_LoadFence)) ||
1137 opc == Op_MemBarRelease ||
1138 opc == Op_StoreFence ||
1139 opc == Op_MemBarReleaseLock ||
1140 opc == Op_MemBarStoreStore ||
1141 opc == Op_StoreStoreFence) {
1142 Node* mem = current->in(0)->in(TypeFunc::Memory);
1143 if (mem->is_MergeMem()) {
1144 MergeMemNode* merge = mem->as_MergeMem();
1145 Node* new_st = merge->memory_at(alias_idx);
1146 if (new_st == merge->base_memory()) {
1147 // Keep searching
1148 current = new_st;
1149 continue;
1150 }
1151 // Save the new memory state for the slice and fall through
1152 // to exit.
1153 result = new_st;
1154 }
1155 }
1156 break;
1157 }
1158 if (result != nullptr) {
1159 st = result;
1160 }
1161 }
1162
1163 // Loop around twice in the case Load -> Initialize -> Store.
1164 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
1165 for (int trip = 0; trip <= 1; trip++) {
1166
1167 if (st->is_Store()) {
1168 Node* st_adr = st->in(MemNode::Address);
1169 if (st_adr != ld_adr) {
1170 // Try harder before giving up. Unify base pointers with casts (e.g., raw/non-raw pointers).
1171 intptr_t st_off = 0;
1172 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_off);
1173 if (ld_base == nullptr) return nullptr;
1174 if (st_base == nullptr) return nullptr;
1175 if (!ld_base->eqv_uncast(st_base, /*keep_deps=*/true)) return nullptr;
1176 if (ld_off != st_off) return nullptr;
1177 if (ld_off == Type::OffsetBot) return nullptr;
1178 // Same base, same offset.
1179 // Possible improvement for arrays: check index value instead of absolute offset.
1180
1181 // At this point we have proven something like this setup:
1182 // B = << base >>
1183 // L = LoadQ(AddP(Check/CastPP(B), #Off))
1184 // S = StoreQ(AddP( B , #Off), V)
1185 // (Actually, we haven't yet proven the Q's are the same.)
1186 // In other words, we are loading from a casted version of
1187 // the same pointer-and-offset that we stored to.
1188 // Casted version may carry a dependency and it is respected.
1189 // Thus, we are able to replace L by V.
1190 }
1191 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
1192 if (store_Opcode() != st->Opcode()) {
1193 return nullptr;
1194 }
1195 // LoadVector/StoreVector needs additional check to ensure the types match.
1196 if (st->is_StoreVector()) {
1197 const TypeVect* in_vt = st->as_StoreVector()->vect_type();
1198 const TypeVect* out_vt = as_LoadVector()->vect_type();
1199 if (in_vt != out_vt) {
1200 return nullptr;
1201 }
1202 }
1203 return st->in(MemNode::ValueIn);
1204 }
1205
1206 // A load from a freshly-created object always returns zero.
1207 // (This can happen after LoadNode::Ideal resets the load's memory input
1208 // to find_captured_store, which returned InitializeNode::zero_memory.)
1209 if (st->is_Proj() && st->in(0)->is_Allocate() &&
1210 (st->in(0) == ld_alloc) &&
1211 (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) {
1212 // return a zero value for the load's basic type
1213 // (This is one of the few places where a generic PhaseTransform
1214 // can create new nodes. Think of it as lazily manifesting
1215 // virtually pre-existing constants.)
1216 if (value_basic_type() != T_VOID) {
1217 if (ReduceBulkZeroing || find_array_copy_clone(ld_alloc, in(MemNode::Memory)) == nullptr) {
1218 // If ReduceBulkZeroing is disabled, we need to check if the allocation does not belong to an
1219 // ArrayCopyNode clone. If it does, then we cannot assume zero since the initialization is done
1220 // by the ArrayCopyNode.
1221 return phase->zerocon(value_basic_type());
1222 }
1223 } else {
1224 // TODO: materialize all-zero vector constant
1225 assert(!isa_Load() || as_Load()->type()->isa_vect(), "");
1226 }
1227 }
1228
1229 // A load from an initialization barrier can match a captured store.
1230 if (st->is_Proj() && st->in(0)->is_Initialize()) {
1231 InitializeNode* init = st->in(0)->as_Initialize();
1232 AllocateNode* alloc = init->allocation();
1233 if ((alloc != nullptr) && (alloc == ld_alloc)) {
1234 // examine a captured store value
1235 st = init->find_captured_store(ld_off, memory_size(), phase);
1236 if (st != nullptr) {
1237 continue; // take one more trip around
1238 }
1239 }
1240 }
1241
1242 // Load boxed value from result of valueOf() call is input parameter.
1243 if (this->is_Load() && ld_adr->is_AddP() &&
1244 (tp != nullptr) && tp->is_ptr_to_boxed_value()) {
1245 intptr_t ignore = 0;
1246 Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore);
1247 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1248 base = bs->step_over_gc_barrier(base);
1249 if (base != nullptr && base->is_Proj() &&
1250 base->as_Proj()->_con == TypeFunc::Parms &&
1251 base->in(0)->is_CallStaticJava() &&
1252 base->in(0)->as_CallStaticJava()->is_boxing_method()) {
1253 return base->in(0)->in(TypeFunc::Parms);
1254 }
1255 }
1256
1257 break;
1258 }
1259
1260 return nullptr;
1261 }
1262
1263 //----------------------is_instance_field_load_with_local_phi------------------
1264 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
1265 if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl &&
1266 in(Address)->is_AddP() ) {
1267 const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr();
1268 // Only instances and boxed values.
1269 if( t_oop != nullptr &&
1270 (t_oop->is_ptr_to_boxed_value() ||
1271 t_oop->is_known_instance_field()) &&
1272 t_oop->offset() != Type::OffsetBot &&
1273 t_oop->offset() != Type::OffsetTop) {
1274 return true;
1275 }
1276 }
1277 return false;
1278 }
1279
1280 //------------------------------Identity---------------------------------------
1281 // Loads are identity if previous store is to same address
1282 Node* LoadNode::Identity(PhaseGVN* phase) {
1283 // If the previous store-maker is the right kind of Store, and the store is
1284 // to the same address, then we are equal to the value stored.
1285 Node* mem = in(Memory);
1286 Node* value = can_see_stored_value(mem, phase);
1287 if( value ) {
1288 // byte, short & char stores truncate naturally.
1289 // A load has to load the truncated value which requires
1290 // some sort of masking operation and that requires an
1291 // Ideal call instead of an Identity call.
1292 if (memory_size() < BytesPerInt) {
1293 // If the input to the store does not fit with the load's result type,
1294 // it must be truncated via an Ideal call.
1295 if (!phase->type(value)->higher_equal(phase->type(this)))
1296 return this;
1297 }
1298 // (This works even when value is a Con, but LoadNode::Value
1299 // usually runs first, producing the singleton type of the Con.)
1300 if (!has_pinned_control_dependency() || value->is_Con()) {
1301 return value;
1302 } else {
1303 return this;
1304 }
1305 }
1306
1307 if (has_pinned_control_dependency()) {
1308 return this;
1309 }
1310 // Search for an existing data phi which was generated before for the same
1311 // instance's field to avoid infinite generation of phis in a loop.
1312 Node *region = mem->in(0);
1313 if (is_instance_field_load_with_local_phi(region)) {
1314 const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr();
1315 int this_index = phase->C->get_alias_index(addr_t);
1316 int this_offset = addr_t->offset();
1317 int this_iid = addr_t->instance_id();
1318 if (!addr_t->is_known_instance() &&
1319 addr_t->is_ptr_to_boxed_value()) {
1320 // Use _idx of address base (could be Phi node) for boxed values.
1321 intptr_t ignore = 0;
1322 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1323 if (base == nullptr) {
1324 return this;
1325 }
1326 this_iid = base->_idx;
1327 }
1328 const Type* this_type = bottom_type();
1329 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1330 Node* phi = region->fast_out(i);
1331 if (phi->is_Phi() && phi != mem &&
1332 phi->as_Phi()->is_same_inst_field(this_type, (int)mem->_idx, this_iid, this_index, this_offset)) {
1333 return phi;
1334 }
1335 }
1336 }
1337
1338 return this;
1339 }
1340
1341 // Construct an equivalent unsigned load.
1342 Node* LoadNode::convert_to_unsigned_load(PhaseGVN& gvn) {
1343 BasicType bt = T_ILLEGAL;
1344 const Type* rt = nullptr;
1345 switch (Opcode()) {
1346 case Op_LoadUB: return this;
1347 case Op_LoadUS: return this;
1348 case Op_LoadB: bt = T_BOOLEAN; rt = TypeInt::UBYTE; break;
1349 case Op_LoadS: bt = T_CHAR; rt = TypeInt::CHAR; break;
1350 default:
1351 assert(false, "no unsigned variant: %s", Name());
1352 return nullptr;
1353 }
1354 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1355 raw_adr_type(), rt, bt, _mo, _control_dependency,
1356 false /*require_atomic_access*/, is_unaligned_access(), is_mismatched_access());
1357 }
1358
1359 // Construct an equivalent signed load.
1360 Node* LoadNode::convert_to_signed_load(PhaseGVN& gvn) {
1361 BasicType bt = T_ILLEGAL;
1362 const Type* rt = nullptr;
1363 switch (Opcode()) {
1364 case Op_LoadUB: bt = T_BYTE; rt = TypeInt::BYTE; break;
1365 case Op_LoadUS: bt = T_SHORT; rt = TypeInt::SHORT; break;
1366 case Op_LoadB: // fall through
1367 case Op_LoadS: // fall through
1368 case Op_LoadI: // fall through
1369 case Op_LoadL: return this;
1370 default:
1371 assert(false, "no signed variant: %s", Name());
1372 return nullptr;
1373 }
1374 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1375 raw_adr_type(), rt, bt, _mo, _control_dependency,
1376 false /*require_atomic_access*/, is_unaligned_access(), is_mismatched_access());
1377 }
1378
1379 bool LoadNode::has_reinterpret_variant(const Type* rt) {
1380 BasicType bt = rt->basic_type();
1381 switch (Opcode()) {
1382 case Op_LoadI: return (bt == T_FLOAT);
1383 case Op_LoadL: return (bt == T_DOUBLE);
1384 case Op_LoadF: return (bt == T_INT);
1385 case Op_LoadD: return (bt == T_LONG);
1386
1387 default: return false;
1388 }
1389 }
1390
1391 Node* LoadNode::convert_to_reinterpret_load(PhaseGVN& gvn, const Type* rt) {
1392 BasicType bt = rt->basic_type();
1393 assert(has_reinterpret_variant(rt), "no reinterpret variant: %s %s", Name(), type2name(bt));
1394 bool is_mismatched = is_mismatched_access();
1395 const TypeRawPtr* raw_type = gvn.type(in(MemNode::Memory))->isa_rawptr();
1396 if (raw_type == nullptr) {
1397 is_mismatched = true; // conservatively match all non-raw accesses as mismatched
1398 }
1399 const int op = Opcode();
1400 bool require_atomic_access = (op == Op_LoadL && ((LoadLNode*)this)->require_atomic_access()) ||
1401 (op == Op_LoadD && ((LoadDNode*)this)->require_atomic_access());
1402 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1403 raw_adr_type(), rt, bt, _mo, _control_dependency,
1404 require_atomic_access, is_unaligned_access(), is_mismatched);
1405 }
1406
1407 bool StoreNode::has_reinterpret_variant(const Type* vt) {
1408 BasicType bt = vt->basic_type();
1409 switch (Opcode()) {
1410 case Op_StoreI: return (bt == T_FLOAT);
1411 case Op_StoreL: return (bt == T_DOUBLE);
1412 case Op_StoreF: return (bt == T_INT);
1413 case Op_StoreD: return (bt == T_LONG);
1414
1415 default: return false;
1416 }
1417 }
1418
1419 Node* StoreNode::convert_to_reinterpret_store(PhaseGVN& gvn, Node* val, const Type* vt) {
1420 BasicType bt = vt->basic_type();
1421 assert(has_reinterpret_variant(vt), "no reinterpret variant: %s %s", Name(), type2name(bt));
1422 const int op = Opcode();
1423 bool require_atomic_access = (op == Op_StoreL && ((StoreLNode*)this)->require_atomic_access()) ||
1424 (op == Op_StoreD && ((StoreDNode*)this)->require_atomic_access());
1425 StoreNode* st = StoreNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1426 raw_adr_type(), val, bt, _mo, require_atomic_access);
1427
1428 bool is_mismatched = is_mismatched_access();
1429 const TypeRawPtr* raw_type = gvn.type(in(MemNode::Memory))->isa_rawptr();
1430 if (raw_type == nullptr) {
1431 is_mismatched = true; // conservatively match all non-raw accesses as mismatched
1432 }
1433 if (is_mismatched) {
1434 st->set_mismatched_access();
1435 }
1436 return st;
1437 }
1438
1439 // We're loading from an object which has autobox behaviour.
1440 // If this object is result of a valueOf call we'll have a phi
1441 // merging a newly allocated object and a load from the cache.
1442 // We want to replace this load with the original incoming
1443 // argument to the valueOf call.
1444 Node* LoadNode::eliminate_autobox(PhaseIterGVN* igvn) {
1445 assert(igvn->C->eliminate_boxing(), "sanity");
1446 intptr_t ignore = 0;
1447 Node* base = AddPNode::Ideal_base_and_offset(in(Address), igvn, ignore);
1448 if ((base == nullptr) || base->is_Phi()) {
1449 // Push the loads from the phi that comes from valueOf up
1450 // through it to allow elimination of the loads and the recovery
1451 // of the original value. It is done in split_through_phi().
1452 return nullptr;
1453 } else if (base->is_Load() ||
1454 (base->is_DecodeN() && base->in(1)->is_Load())) {
1455 // Eliminate the load of boxed value for integer types from the cache
1456 // array by deriving the value from the index into the array.
1457 // Capture the offset of the load and then reverse the computation.
1458
1459 // Get LoadN node which loads a boxing object from 'cache' array.
1460 if (base->is_DecodeN()) {
1461 base = base->in(1);
1462 }
1463 if (!base->in(Address)->is_AddP()) {
1464 return nullptr; // Complex address
1465 }
1466 AddPNode* address = base->in(Address)->as_AddP();
1467 Node* cache_base = address->in(AddPNode::Base);
1468 if ((cache_base != nullptr) && cache_base->is_DecodeN()) {
1469 // Get ConP node which is static 'cache' field.
1470 cache_base = cache_base->in(1);
1471 }
1472 if ((cache_base != nullptr) && cache_base->is_Con()) {
1473 const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr();
1474 if ((base_type != nullptr) && base_type->is_autobox_cache()) {
1475 Node* elements[4];
1476 int shift = exact_log2(type2aelembytes(T_OBJECT));
1477 int count = address->unpack_offsets(elements, ARRAY_SIZE(elements));
1478 if (count > 0 && elements[0]->is_Con() &&
1479 (count == 1 ||
1480 (count == 2 && elements[1]->Opcode() == Op_LShiftX &&
1481 elements[1]->in(2) == igvn->intcon(shift)))) {
1482 ciObjArray* array = base_type->const_oop()->as_obj_array();
1483 // Fetch the box object cache[0] at the base of the array and get its value
1484 ciInstance* box = array->obj_at(0)->as_instance();
1485 ciInstanceKlass* ik = box->klass()->as_instance_klass();
1486 assert(ik->is_box_klass(), "sanity");
1487 assert(ik->nof_nonstatic_fields() == 1, "change following code");
1488 if (ik->nof_nonstatic_fields() == 1) {
1489 // This should be true nonstatic_field_at requires calling
1490 // nof_nonstatic_fields so check it anyway
1491 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1492 BasicType bt = c.basic_type();
1493 // Only integer types have boxing cache.
1494 assert(bt == T_BOOLEAN || bt == T_CHAR ||
1495 bt == T_BYTE || bt == T_SHORT ||
1496 bt == T_INT || bt == T_LONG, "wrong type = %s", type2name(bt));
1497 jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int();
1498 if (cache_low != (int)cache_low) {
1499 return nullptr; // should not happen since cache is array indexed by value
1500 }
1501 jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift);
1502 if (offset != (int)offset) {
1503 return nullptr; // should not happen since cache is array indexed by value
1504 }
1505 // Add up all the offsets making of the address of the load
1506 Node* result = elements[0];
1507 for (int i = 1; i < count; i++) {
1508 result = igvn->transform(new AddXNode(result, elements[i]));
1509 }
1510 // Remove the constant offset from the address and then
1511 result = igvn->transform(new AddXNode(result, igvn->MakeConX(-(int)offset)));
1512 // remove the scaling of the offset to recover the original index.
1513 if (result->Opcode() == Op_LShiftX && result->in(2) == igvn->intcon(shift)) {
1514 // Peel the shift off directly but wrap it in a dummy node
1515 // since Ideal can't return existing nodes
1516 igvn->_worklist.push(result); // remove dead node later
1517 result = new RShiftXNode(result->in(1), igvn->intcon(0));
1518 } else if (result->is_Add() && result->in(2)->is_Con() &&
1519 result->in(1)->Opcode() == Op_LShiftX &&
1520 result->in(1)->in(2) == igvn->intcon(shift)) {
1521 // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z)
1522 // but for boxing cache access we know that X<<Z will not overflow
1523 // (there is range check) so we do this optimizatrion by hand here.
1524 igvn->_worklist.push(result); // remove dead node later
1525 Node* add_con = new RShiftXNode(result->in(2), igvn->intcon(shift));
1526 result = new AddXNode(result->in(1)->in(1), igvn->transform(add_con));
1527 } else {
1528 result = new RShiftXNode(result, igvn->intcon(shift));
1529 }
1530 #ifdef _LP64
1531 if (bt != T_LONG) {
1532 result = new ConvL2INode(igvn->transform(result));
1533 }
1534 #else
1535 if (bt == T_LONG) {
1536 result = new ConvI2LNode(igvn->transform(result));
1537 }
1538 #endif
1539 // Boxing/unboxing can be done from signed & unsigned loads (e.g. LoadUB -> ... -> LoadB pair).
1540 // Need to preserve unboxing load type if it is unsigned.
1541 switch(this->Opcode()) {
1542 case Op_LoadUB:
1543 result = new AndINode(igvn->transform(result), igvn->intcon(0xFF));
1544 break;
1545 case Op_LoadUS:
1546 result = new AndINode(igvn->transform(result), igvn->intcon(0xFFFF));
1547 break;
1548 }
1549 return result;
1550 }
1551 }
1552 }
1553 }
1554 }
1555 return nullptr;
1556 }
1557
1558 static bool stable_phi(PhiNode* phi, PhaseGVN *phase) {
1559 Node* region = phi->in(0);
1560 if (region == nullptr) {
1561 return false; // Wait stable graph
1562 }
1563 uint cnt = phi->req();
1564 for (uint i = 1; i < cnt; i++) {
1565 Node* rc = region->in(i);
1566 if (rc == nullptr || phase->type(rc) == Type::TOP)
1567 return false; // Wait stable graph
1568 Node* in = phi->in(i);
1569 if (in == nullptr || phase->type(in) == Type::TOP)
1570 return false; // Wait stable graph
1571 }
1572 return true;
1573 }
1574
1575 //------------------------------split_through_phi------------------------------
1576 // Check whether a call to 'split_through_phi' would split this load through the
1577 // Phi *base*. This method is essentially a copy of the validations performed
1578 // by 'split_through_phi'. The first use of this method was in EA code as part
1579 // of simplification of allocation merges.
1580 // Some differences from original method (split_through_phi):
1581 // - If base->is_CastPP(): base = base->in(1)
1582 bool LoadNode::can_split_through_phi_base(PhaseGVN* phase) {
1583 Node* mem = in(Memory);
1584 Node* address = in(Address);
1585 intptr_t ignore = 0;
1586 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1587
1588 if (base->is_CastPP()) {
1589 base = base->in(1);
1590 }
1591
1592 if (req() > 3 || base == nullptr || !base->is_Phi()) {
1593 return false;
1594 }
1595
1596 if (!mem->is_Phi()) {
1597 if (!MemNode::all_controls_dominate(mem, base->in(0))) {
1598 return false;
1599 }
1600 } else if (base->in(0) != mem->in(0)) {
1601 if (!MemNode::all_controls_dominate(mem, base->in(0))) {
1602 return false;
1603 }
1604 }
1605
1606 return true;
1607 }
1608
1609 //------------------------------split_through_phi------------------------------
1610 // Split instance or boxed field load through Phi.
1611 Node* LoadNode::split_through_phi(PhaseGVN* phase, bool ignore_missing_instance_id) {
1612 if (req() > 3) {
1613 assert(is_LoadVector() && Opcode() != Op_LoadVector, "load has too many inputs");
1614 // LoadVector subclasses such as LoadVectorMasked have extra inputs that the logic below doesn't take into account
1615 return nullptr;
1616 }
1617 Node* mem = in(Memory);
1618 Node* address = in(Address);
1619 const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr();
1620
1621 assert((t_oop != nullptr) &&
1622 (ignore_missing_instance_id ||
1623 t_oop->is_known_instance_field() ||
1624 t_oop->is_ptr_to_boxed_value()), "invalid conditions");
1625
1626 Compile* C = phase->C;
1627 intptr_t ignore = 0;
1628 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1629 bool base_is_phi = (base != nullptr) && base->is_Phi();
1630 bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() &&
1631 (base != nullptr) && (base == address->in(AddPNode::Base)) &&
1632 phase->type(base)->higher_equal(TypePtr::NOTNULL);
1633
1634 if (!((mem->is_Phi() || base_is_phi) &&
1635 (ignore_missing_instance_id || load_boxed_values || t_oop->is_known_instance_field()))) {
1636 return nullptr; // Neither memory or base are Phi
1637 }
1638
1639 if (mem->is_Phi()) {
1640 if (!stable_phi(mem->as_Phi(), phase)) {
1641 return nullptr; // Wait stable graph
1642 }
1643 uint cnt = mem->req();
1644 // Check for loop invariant memory.
1645 if (cnt == 3) {
1646 for (uint i = 1; i < cnt; i++) {
1647 Node* in = mem->in(i);
1648 Node* m = optimize_memory_chain(in, t_oop, this, phase);
1649 if (m == mem) {
1650 if (i == 1) {
1651 // if the first edge was a loop, check second edge too.
1652 // If both are replaceable - we are in an infinite loop
1653 Node *n = optimize_memory_chain(mem->in(2), t_oop, this, phase);
1654 if (n == mem) {
1655 break;
1656 }
1657 }
1658 set_req(Memory, mem->in(cnt - i));
1659 return this; // made change
1660 }
1661 }
1662 }
1663 }
1664 if (base_is_phi) {
1665 if (!stable_phi(base->as_Phi(), phase)) {
1666 return nullptr; // Wait stable graph
1667 }
1668 uint cnt = base->req();
1669 // Check for loop invariant memory.
1670 if (cnt == 3) {
1671 for (uint i = 1; i < cnt; i++) {
1672 if (base->in(i) == base) {
1673 return nullptr; // Wait stable graph
1674 }
1675 }
1676 }
1677 }
1678
1679 // Split through Phi (see original code in loopopts.cpp).
1680 assert(ignore_missing_instance_id || C->have_alias_type(t_oop), "instance should have alias type");
1681
1682 // Do nothing here if Identity will find a value
1683 // (to avoid infinite chain of value phis generation).
1684 if (this != Identity(phase)) {
1685 return nullptr;
1686 }
1687
1688 // Select Region to split through.
1689 Node* region;
1690 DomResult dom_result = DomResult::Dominate;
1691 if (!base_is_phi) {
1692 assert(mem->is_Phi(), "sanity");
1693 region = mem->in(0);
1694 // Skip if the region dominates some control edge of the address.
1695 // We will check `dom_result` later.
1696 dom_result = MemNode::maybe_all_controls_dominate(address, region);
1697 } else if (!mem->is_Phi()) {
1698 assert(base_is_phi, "sanity");
1699 region = base->in(0);
1700 // Skip if the region dominates some control edge of the memory.
1701 // We will check `dom_result` later.
1702 dom_result = MemNode::maybe_all_controls_dominate(mem, region);
1703 } else if (base->in(0) != mem->in(0)) {
1704 assert(base_is_phi && mem->is_Phi(), "sanity");
1705 dom_result = MemNode::maybe_all_controls_dominate(mem, base->in(0));
1706 if (dom_result == DomResult::Dominate) {
1707 region = base->in(0);
1708 } else {
1709 dom_result = MemNode::maybe_all_controls_dominate(address, mem->in(0));
1710 if (dom_result == DomResult::Dominate) {
1711 region = mem->in(0);
1712 }
1713 // Otherwise we encountered a complex graph.
1714 }
1715 } else {
1716 assert(base->in(0) == mem->in(0), "sanity");
1717 region = mem->in(0);
1718 }
1719
1720 PhaseIterGVN* igvn = phase->is_IterGVN();
1721 if (dom_result != DomResult::Dominate) {
1722 if (dom_result == DomResult::EncounteredDeadCode) {
1723 // There is some dead code which eventually will be removed in IGVN.
1724 // Once this is the case, we get an unambiguous dominance result.
1725 // Push the node to the worklist again until the dead code is removed.
1726 igvn->_worklist.push(this);
1727 }
1728 return nullptr;
1729 }
1730
1731 Node* phi = nullptr;
1732 const Type* this_type = this->bottom_type();
1733 if (t_oop != nullptr && (t_oop->is_known_instance_field() || load_boxed_values)) {
1734 int this_index = C->get_alias_index(t_oop);
1735 int this_offset = t_oop->offset();
1736 int this_iid = t_oop->is_known_instance_field() ? t_oop->instance_id() : base->_idx;
1737 phi = new PhiNode(region, this_type, nullptr, mem->_idx, this_iid, this_index, this_offset);
1738 } else if (ignore_missing_instance_id) {
1739 phi = new PhiNode(region, this_type, nullptr, mem->_idx);
1740 } else {
1741 return nullptr;
1742 }
1743
1744 for (uint i = 1; i < region->req(); i++) {
1745 Node* x;
1746 Node* the_clone = nullptr;
1747 Node* in = region->in(i);
1748 if (region->is_CountedLoop() && region->as_Loop()->is_strip_mined() && i == LoopNode::EntryControl &&
1749 in != nullptr && in->is_OuterStripMinedLoop()) {
1750 // No node should go in the outer strip mined loop
1751 in = in->in(LoopNode::EntryControl);
1752 }
1753 if (in == nullptr || in == C->top()) {
1754 x = C->top(); // Dead path? Use a dead data op
1755 } else {
1756 x = this->clone(); // Else clone up the data op
1757 the_clone = x; // Remember for possible deletion.
1758 // Alter data node to use pre-phi inputs
1759 if (this->in(0) == region) {
1760 x->set_req(0, in);
1761 } else {
1762 x->set_req(0, nullptr);
1763 }
1764 if (mem->is_Phi() && (mem->in(0) == region)) {
1765 x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone.
1766 }
1767 if (address->is_Phi() && address->in(0) == region) {
1768 x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone
1769 }
1770 if (base_is_phi && (base->in(0) == region)) {
1771 Node* base_x = base->in(i); // Clone address for loads from boxed objects.
1772 Node* adr_x = phase->transform(new AddPNode(base_x,base_x,address->in(AddPNode::Offset)));
1773 x->set_req(Address, adr_x);
1774 }
1775 }
1776 // Check for a 'win' on some paths
1777 const Type *t = x->Value(igvn);
1778
1779 bool singleton = t->singleton();
1780
1781 // See comments in PhaseIdealLoop::split_thru_phi().
1782 if (singleton && t == Type::TOP) {
1783 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1784 }
1785
1786 if (singleton) {
1787 x = igvn->makecon(t);
1788 } else {
1789 // We now call Identity to try to simplify the cloned node.
1790 // Note that some Identity methods call phase->type(this).
1791 // Make sure that the type array is big enough for
1792 // our new node, even though we may throw the node away.
1793 // (This tweaking with igvn only works because x is a new node.)
1794 igvn->set_type(x, t);
1795 // If x is a TypeNode, capture any more-precise type permanently into Node
1796 // otherwise it will be not updated during igvn->transform since
1797 // igvn->type(x) is set to x->Value() already.
1798 x->raise_bottom_type(t);
1799 Node* y = x->Identity(igvn);
1800 if (y != x) {
1801 x = y;
1802 } else {
1803 y = igvn->hash_find_insert(x);
1804 if (y) {
1805 x = y;
1806 } else {
1807 // Else x is a new node we are keeping
1808 // We do not need register_new_node_with_optimizer
1809 // because set_type has already been called.
1810 igvn->_worklist.push(x);
1811 }
1812 }
1813 }
1814 if (x != the_clone && the_clone != nullptr) {
1815 igvn->remove_dead_node(the_clone);
1816 }
1817 phi->set_req(i, x);
1818 }
1819 // Record Phi
1820 igvn->register_new_node_with_optimizer(phi);
1821 return phi;
1822 }
1823
1824 AllocateNode* LoadNode::is_new_object_mark_load() const {
1825 if (Opcode() == Op_LoadX) {
1826 Node* address = in(MemNode::Address);
1827 AllocateNode* alloc = AllocateNode::Ideal_allocation(address);
1828 Node* mem = in(MemNode::Memory);
1829 if (alloc != nullptr && mem->is_Proj() &&
1830 mem->in(0) != nullptr &&
1831 mem->in(0) == alloc->initialization() &&
1832 alloc->initialization()->proj_out_or_null(0) != nullptr) {
1833 return alloc;
1834 }
1835 }
1836 return nullptr;
1837 }
1838
1839
1840 //------------------------------Ideal------------------------------------------
1841 // If the load is from Field memory and the pointer is non-null, it might be possible to
1842 // zero out the control input.
1843 // If the offset is constant and the base is an object allocation,
1844 // try to hook me up to the exact initializing store.
1845 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1846 if (has_pinned_control_dependency()) {
1847 return nullptr;
1848 }
1849 Node* p = MemNode::Ideal_common(phase, can_reshape);
1850 if (p) return (p == NodeSentinel) ? nullptr : p;
1851
1852 Node* ctrl = in(MemNode::Control);
1853 Node* address = in(MemNode::Address);
1854 bool progress = false;
1855
1856 bool addr_mark = ((phase->type(address)->isa_oopptr() || phase->type(address)->isa_narrowoop()) &&
1857 phase->type(address)->is_ptr()->offset() == oopDesc::mark_offset_in_bytes());
1858
1859 // Skip up past a SafePoint control. Cannot do this for Stores because
1860 // pointer stores & cardmarks must stay on the same side of a SafePoint.
1861 if( ctrl != nullptr && ctrl->Opcode() == Op_SafePoint &&
1862 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw &&
1863 !addr_mark &&
1864 (depends_only_on_test() || has_unknown_control_dependency())) {
1865 ctrl = ctrl->in(0);
1866 set_req(MemNode::Control,ctrl);
1867 progress = true;
1868 }
1869
1870 intptr_t ignore = 0;
1871 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1872 if (base != nullptr
1873 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
1874 // Check for useless control edge in some common special cases
1875 if (in(MemNode::Control) != nullptr
1876 && can_remove_control()
1877 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1878 && all_controls_dominate(base, phase->C->start())) {
1879 // A method-invariant, non-null address (constant or 'this' argument).
1880 set_req(MemNode::Control, nullptr);
1881 progress = true;
1882 }
1883 }
1884
1885 Node* mem = in(MemNode::Memory);
1886 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1887
1888 if (can_reshape && (addr_t != nullptr)) {
1889 // try to optimize our memory input
1890 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase);
1891 if (opt_mem != mem) {
1892 set_req_X(MemNode::Memory, opt_mem, phase);
1893 if (phase->type( opt_mem ) == Type::TOP) return nullptr;
1894 return this;
1895 }
1896 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1897 if ((t_oop != nullptr) &&
1898 (t_oop->is_known_instance_field() ||
1899 t_oop->is_ptr_to_boxed_value())) {
1900 PhaseIterGVN *igvn = phase->is_IterGVN();
1901 assert(igvn != nullptr, "must be PhaseIterGVN when can_reshape is true");
1902 if (igvn->_worklist.member(opt_mem)) {
1903 // Delay this transformation until memory Phi is processed.
1904 igvn->_worklist.push(this);
1905 return nullptr;
1906 }
1907 // Split instance field load through Phi.
1908 Node* result = split_through_phi(phase);
1909 if (result != nullptr) return result;
1910
1911 if (t_oop->is_ptr_to_boxed_value()) {
1912 Node* result = eliminate_autobox(igvn);
1913 if (result != nullptr) return result;
1914 }
1915 }
1916 }
1917
1918 // Is there a dominating load that loads the same value? Leave
1919 // anything that is not a load of a field/array element (like
1920 // barriers etc.) alone
1921 if (in(0) != nullptr && !adr_type()->isa_rawptr() && can_reshape) {
1922 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) {
1923 Node *use = mem->fast_out(i);
1924 if (use != this &&
1925 use->Opcode() == Opcode() &&
1926 use->in(0) != nullptr &&
1927 use->in(0) != in(0) &&
1928 use->in(Address) == in(Address)) {
1929 Node* ctl = in(0);
1930 for (int i = 0; i < 10 && ctl != nullptr; i++) {
1931 ctl = IfNode::up_one_dom(ctl);
1932 if (ctl == use->in(0)) {
1933 set_req(0, use->in(0));
1934 return this;
1935 }
1936 }
1937 }
1938 }
1939 }
1940
1941 // Check for prior store with a different base or offset; make Load
1942 // independent. Skip through any number of them. Bail out if the stores
1943 // are in an endless dead cycle and report no progress. This is a key
1944 // transform for Reflection. However, if after skipping through the Stores
1945 // we can't then fold up against a prior store do NOT do the transform as
1946 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
1947 // array memory alive twice: once for the hoisted Load and again after the
1948 // bypassed Store. This situation only works if EVERYBODY who does
1949 // anti-dependence work knows how to bypass. I.e. we need all
1950 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
1951 // the alias index stuff. So instead, peek through Stores and IFF we can
1952 // fold up, do so.
1953 Node* prev_mem = find_previous_store(phase);
1954 if (prev_mem != nullptr) {
1955 Node* value = can_see_arraycopy_value(prev_mem, phase);
1956 if (value != nullptr) {
1957 return value;
1958 }
1959 }
1960 // Steps (a), (b): Walk past independent stores to find an exact match.
1961 if (prev_mem != nullptr && prev_mem != in(MemNode::Memory)) {
1962 // (c) See if we can fold up on the spot, but don't fold up here.
1963 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
1964 // just return a prior value, which is done by Identity calls.
1965 if (can_see_stored_value(prev_mem, phase)) {
1966 // Make ready for step (d):
1967 set_req_X(MemNode::Memory, prev_mem, phase);
1968 return this;
1969 }
1970 }
1971
1972 return progress ? this : nullptr;
1973 }
1974
1975 // Helper to recognize certain Klass fields which are invariant across
1976 // some group of array types (e.g., int[] or all T[] where T < Object).
1977 const Type*
1978 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1979 ciKlass* klass) const {
1980 assert(!UseCompactObjectHeaders || tkls->offset() != in_bytes(Klass::prototype_header_offset()),
1981 "must not happen");
1982 if (tkls->offset() == in_bytes(Klass::access_flags_offset())) {
1983 // The field is Klass::_access_flags. Return its (constant) value.
1984 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1985 assert(Opcode() == Op_LoadUS, "must load an unsigned short from _access_flags");
1986 return TypeInt::make(klass->access_flags());
1987 }
1988 if (tkls->offset() == in_bytes(Klass::misc_flags_offset())) {
1989 // The field is Klass::_misc_flags. Return its (constant) value.
1990 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1991 assert(Opcode() == Op_LoadUB, "must load an unsigned byte from _misc_flags");
1992 return TypeInt::make(klass->misc_flags());
1993 }
1994 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) {
1995 // The field is Klass::_layout_helper. Return its constant value if known.
1996 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
1997 return TypeInt::make(klass->layout_helper());
1998 }
1999
2000 // No match.
2001 return nullptr;
2002 }
2003
2004 //------------------------------Value-----------------------------------------
2005 const Type* LoadNode::Value(PhaseGVN* phase) const {
2006 // Either input is TOP ==> the result is TOP
2007 Node* mem = in(MemNode::Memory);
2008 const Type *t1 = phase->type(mem);
2009 if (t1 == Type::TOP) return Type::TOP;
2010 Node* adr = in(MemNode::Address);
2011 const TypePtr* tp = phase->type(adr)->isa_ptr();
2012 if (tp == nullptr || tp->empty()) return Type::TOP;
2013 int off = tp->offset();
2014 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
2015 Compile* C = phase->C;
2016
2017 // If we are loading from a freshly-allocated object, produce a zero,
2018 // if the load is provably beyond the header of the object.
2019 // (Also allow a variable load from a fresh array to produce zero.)
2020 const TypeOopPtr* tinst = tp->isa_oopptr();
2021 bool is_instance = (tinst != nullptr) && tinst->is_known_instance_field();
2022 Node* value = can_see_stored_value(mem, phase);
2023 if (value != nullptr && value->is_Con()) {
2024 assert(value->bottom_type()->higher_equal(_type), "sanity");
2025 return value->bottom_type();
2026 }
2027
2028 // Try to guess loaded type from pointer type
2029 if (tp->isa_aryptr()) {
2030 const TypeAryPtr* ary = tp->is_aryptr();
2031 const Type* t = ary->elem();
2032
2033 // Determine whether the reference is beyond the header or not, by comparing
2034 // the offset against the offset of the start of the array's data.
2035 // Different array types begin at slightly different offsets (12 vs. 16).
2036 // We choose T_BYTE as an example base type that is least restrictive
2037 // as to alignment, which will therefore produce the smallest
2038 // possible base offset.
2039 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
2040 const bool off_beyond_header = (off >= min_base_off);
2041
2042 // Try to constant-fold a stable array element.
2043 if (FoldStableValues && !is_mismatched_access() && ary->is_stable()) {
2044 // Make sure the reference is not into the header and the offset is constant
2045 ciObject* aobj = ary->const_oop();
2046 if (aobj != nullptr && off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) {
2047 int stable_dimension = (ary->stable_dimension() > 0 ? ary->stable_dimension() - 1 : 0);
2048 const Type* con_type = Type::make_constant_from_array_element(aobj->as_array(), off,
2049 stable_dimension,
2050 value_basic_type(), is_unsigned());
2051 if (con_type != nullptr) {
2052 return con_type;
2053 }
2054 }
2055 }
2056
2057 // Don't do this for integer types. There is only potential profit if
2058 // the element type t is lower than _type; that is, for int types, if _type is
2059 // more restrictive than t. This only happens here if one is short and the other
2060 // char (both 16 bits), and in those cases we've made an intentional decision
2061 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
2062 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
2063 //
2064 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
2065 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
2066 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
2067 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
2068 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
2069 // In fact, that could have been the original type of p1, and p1 could have
2070 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
2071 // expression (LShiftL quux 3) independently optimized to the constant 8.
2072 if ((t->isa_int() == nullptr) && (t->isa_long() == nullptr)
2073 && (_type->isa_vect() == nullptr)
2074 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
2075 // t might actually be lower than _type, if _type is a unique
2076 // concrete subclass of abstract class t.
2077 if (off_beyond_header || off == Type::OffsetBot) { // is the offset beyond the header?
2078 const Type* jt = t->join_speculative(_type);
2079 // In any case, do not allow the join, per se, to empty out the type.
2080 if (jt->empty() && !t->empty()) {
2081 // This can happen if a interface-typed array narrows to a class type.
2082 jt = _type;
2083 }
2084 #ifdef ASSERT
2085 if (phase->C->eliminate_boxing() && adr->is_AddP()) {
2086 // The pointers in the autobox arrays are always non-null
2087 Node* base = adr->in(AddPNode::Base);
2088 if ((base != nullptr) && base->is_DecodeN()) {
2089 // Get LoadN node which loads IntegerCache.cache field
2090 base = base->in(1);
2091 }
2092 if ((base != nullptr) && base->is_Con()) {
2093 const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr();
2094 if ((base_type != nullptr) && base_type->is_autobox_cache()) {
2095 // It could be narrow oop
2096 assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity");
2097 }
2098 }
2099 }
2100 #endif
2101 return jt;
2102 }
2103 }
2104 } else if (tp->base() == Type::InstPtr) {
2105 assert( off != Type::OffsetBot ||
2106 // arrays can be cast to Objects
2107 !tp->isa_instptr() ||
2108 tp->is_instptr()->instance_klass()->is_java_lang_Object() ||
2109 // unsafe field access may not have a constant offset
2110 C->has_unsafe_access(),
2111 "Field accesses must be precise" );
2112 // For oop loads, we expect the _type to be precise.
2113
2114 // Optimize loads from constant fields.
2115 const TypeInstPtr* tinst = tp->is_instptr();
2116 ciObject* const_oop = tinst->const_oop();
2117 if (!is_mismatched_access() && off != Type::OffsetBot && const_oop != nullptr && const_oop->is_instance()) {
2118 const Type* con_type = Type::make_constant_from_field(const_oop->as_instance(), off, is_unsigned(), value_basic_type());
2119 if (con_type != nullptr) {
2120 return con_type;
2121 }
2122 }
2123 } else if (tp->base() == Type::KlassPtr || tp->base() == Type::InstKlassPtr || tp->base() == Type::AryKlassPtr) {
2124 assert(off != Type::OffsetBot ||
2125 !tp->isa_instklassptr() ||
2126 // arrays can be cast to Objects
2127 tp->isa_instklassptr()->instance_klass()->is_java_lang_Object() ||
2128 // also allow array-loading from the primary supertype
2129 // array during subtype checks
2130 Opcode() == Op_LoadKlass,
2131 "Field accesses must be precise");
2132 // For klass/static loads, we expect the _type to be precise
2133 } else if (tp->base() == Type::RawPtr && adr->is_Load() && off == 0) {
2134 /* With mirrors being an indirect in the Klass*
2135 * the VM is now using two loads. LoadKlass(LoadP(LoadP(Klass, mirror_offset), zero_offset))
2136 * The LoadP from the Klass has a RawPtr type (see LibraryCallKit::load_mirror_from_klass).
2137 *
2138 * So check the type and klass of the node before the LoadP.
2139 */
2140 Node* adr2 = adr->in(MemNode::Address);
2141 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2142 if (tkls != nullptr && !StressReflectiveCode) {
2143 if (tkls->is_loaded() && tkls->klass_is_exact() && tkls->offset() == in_bytes(Klass::java_mirror_offset())) {
2144 ciKlass* klass = tkls->exact_klass();
2145 assert(adr->Opcode() == Op_LoadP, "must load an oop from _java_mirror");
2146 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
2147 return TypeInstPtr::make(klass->java_mirror());
2148 }
2149 }
2150 }
2151
2152 const TypeKlassPtr *tkls = tp->isa_klassptr();
2153 if (tkls != nullptr) {
2154 if (tkls->is_loaded() && tkls->klass_is_exact()) {
2155 ciKlass* klass = tkls->exact_klass();
2156 // We are loading a field from a Klass metaobject whose identity
2157 // is known at compile time (the type is "exact" or "precise").
2158 // Check for fields we know are maintained as constants by the VM.
2159 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) {
2160 // The field is Klass::_super_check_offset. Return its (constant) value.
2161 // (Folds up type checking code.)
2162 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
2163 return TypeInt::make(klass->super_check_offset());
2164 }
2165 if (UseCompactObjectHeaders) {
2166 if (tkls->offset() == in_bytes(Klass::prototype_header_offset())) {
2167 // The field is Klass::_prototype_header. Return its (constant) value.
2168 assert(this->Opcode() == Op_LoadX, "must load a proper type from _prototype_header");
2169 return TypeX::make(klass->prototype_header());
2170 }
2171 }
2172 // Compute index into primary_supers array
2173 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
2174 // Check for overflowing; use unsigned compare to handle the negative case.
2175 if( depth < ciKlass::primary_super_limit() ) {
2176 // The field is an element of Klass::_primary_supers. Return its (constant) value.
2177 // (Folds up type checking code.)
2178 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
2179 ciKlass *ss = klass->super_of_depth(depth);
2180 return ss ? TypeKlassPtr::make(ss, Type::trust_interfaces) : TypePtr::NULL_PTR;
2181 }
2182 const Type* aift = load_array_final_field(tkls, klass);
2183 if (aift != nullptr) return aift;
2184 }
2185
2186 // We can still check if we are loading from the primary_supers array at a
2187 // shallow enough depth. Even though the klass is not exact, entries less
2188 // than or equal to its super depth are correct.
2189 if (tkls->is_loaded()) {
2190 ciKlass* klass = nullptr;
2191 if (tkls->isa_instklassptr()) {
2192 klass = tkls->is_instklassptr()->instance_klass();
2193 } else {
2194 int dims;
2195 const Type* inner = tkls->is_aryklassptr()->base_element_type(dims);
2196 if (inner->isa_instklassptr()) {
2197 klass = inner->is_instklassptr()->instance_klass();
2198 klass = ciObjArrayKlass::make(klass, dims);
2199 }
2200 }
2201 if (klass != nullptr) {
2202 // Compute index into primary_supers array
2203 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
2204 // Check for overflowing; use unsigned compare to handle the negative case.
2205 if (depth < ciKlass::primary_super_limit() &&
2206 depth <= klass->super_depth()) { // allow self-depth checks to handle self-check case
2207 // The field is an element of Klass::_primary_supers. Return its (constant) value.
2208 // (Folds up type checking code.)
2209 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
2210 ciKlass *ss = klass->super_of_depth(depth);
2211 return ss ? TypeKlassPtr::make(ss, Type::trust_interfaces) : TypePtr::NULL_PTR;
2212 }
2213 }
2214 }
2215
2216 // If the type is enough to determine that the thing is not an array,
2217 // we can give the layout_helper a positive interval type.
2218 // This will help short-circuit some reflective code.
2219 if (tkls->offset() == in_bytes(Klass::layout_helper_offset()) &&
2220 tkls->isa_instklassptr() && // not directly typed as an array
2221 !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
2222 ) {
2223 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
2224 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
2225 // The key property of this type is that it folds up tests
2226 // for array-ness, since it proves that the layout_helper is positive.
2227 // Thus, a generic value like the basic object layout helper works fine.
2228 return TypeInt::make(min_size, max_jint, Type::WidenMin);
2229 }
2230 }
2231
2232 bool is_vect = (_type->isa_vect() != nullptr);
2233 if (is_instance && !is_vect) {
2234 // If we have an instance type and our memory input is the
2235 // programs's initial memory state, there is no matching store,
2236 // so just return a zero of the appropriate type -
2237 // except if it is vectorized - then we have no zero constant.
2238 Node *mem = in(MemNode::Memory);
2239 if (mem->is_Parm() && mem->in(0)->is_Start()) {
2240 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
2241 return Type::get_zero_type(_type->basic_type());
2242 }
2243 }
2244
2245 if (!UseCompactObjectHeaders) {
2246 Node* alloc = is_new_object_mark_load();
2247 if (alloc != nullptr) {
2248 return TypeX::make(markWord::prototype().value());
2249 }
2250 }
2251
2252 return _type;
2253 }
2254
2255 //------------------------------match_edge-------------------------------------
2256 // Do we Match on this edge index or not? Match only the address.
2257 uint LoadNode::match_edge(uint idx) const {
2258 return idx == MemNode::Address;
2259 }
2260
2261 //--------------------------LoadBNode::Ideal--------------------------------------
2262 //
2263 // If the previous store is to the same address as this load,
2264 // and the value stored was larger than a byte, replace this load
2265 // with the value stored truncated to a byte. If no truncation is
2266 // needed, the replacement is done in LoadNode::Identity().
2267 //
2268 Node* LoadBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2269 Node* mem = in(MemNode::Memory);
2270 Node* value = can_see_stored_value(mem,phase);
2271 if (value != nullptr) {
2272 Node* narrow = Compile::narrow_value(T_BYTE, value, _type, phase, false);
2273 if (narrow != value) {
2274 return narrow;
2275 }
2276 }
2277 // Identity call will handle the case where truncation is not needed.
2278 return LoadNode::Ideal(phase, can_reshape);
2279 }
2280
2281 const Type* LoadBNode::Value(PhaseGVN* phase) const {
2282 Node* mem = in(MemNode::Memory);
2283 Node* value = can_see_stored_value(mem,phase);
2284 if (value != nullptr && value->is_Con() &&
2285 !value->bottom_type()->higher_equal(_type)) {
2286 // If the input to the store does not fit with the load's result type,
2287 // it must be truncated. We can't delay until Ideal call since
2288 // a singleton Value is needed for split_thru_phi optimization.
2289 int con = value->get_int();
2290 return TypeInt::make((con << 24) >> 24);
2291 }
2292 return LoadNode::Value(phase);
2293 }
2294
2295 //--------------------------LoadUBNode::Ideal-------------------------------------
2296 //
2297 // If the previous store is to the same address as this load,
2298 // and the value stored was larger than a byte, replace this load
2299 // with the value stored truncated to a byte. If no truncation is
2300 // needed, the replacement is done in LoadNode::Identity().
2301 //
2302 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2303 Node* mem = in(MemNode::Memory);
2304 Node* value = can_see_stored_value(mem, phase);
2305 if (value != nullptr) {
2306 Node* narrow = Compile::narrow_value(T_BOOLEAN, value, _type, phase, false);
2307 if (narrow != value) {
2308 return narrow;
2309 }
2310 }
2311 // Identity call will handle the case where truncation is not needed.
2312 return LoadNode::Ideal(phase, can_reshape);
2313 }
2314
2315 const Type* LoadUBNode::Value(PhaseGVN* phase) const {
2316 Node* mem = in(MemNode::Memory);
2317 Node* value = can_see_stored_value(mem,phase);
2318 if (value != nullptr && value->is_Con() &&
2319 !value->bottom_type()->higher_equal(_type)) {
2320 // If the input to the store does not fit with the load's result type,
2321 // it must be truncated. We can't delay until Ideal call since
2322 // a singleton Value is needed for split_thru_phi optimization.
2323 int con = value->get_int();
2324 return TypeInt::make(con & 0xFF);
2325 }
2326 return LoadNode::Value(phase);
2327 }
2328
2329 //--------------------------LoadUSNode::Ideal-------------------------------------
2330 //
2331 // If the previous store is to the same address as this load,
2332 // and the value stored was larger than a char, replace this load
2333 // with the value stored truncated to a char. If no truncation is
2334 // needed, the replacement is done in LoadNode::Identity().
2335 //
2336 Node* LoadUSNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2337 Node* mem = in(MemNode::Memory);
2338 Node* value = can_see_stored_value(mem,phase);
2339 if (value != nullptr) {
2340 Node* narrow = Compile::narrow_value(T_CHAR, value, _type, phase, false);
2341 if (narrow != value) {
2342 return narrow;
2343 }
2344 }
2345 // Identity call will handle the case where truncation is not needed.
2346 return LoadNode::Ideal(phase, can_reshape);
2347 }
2348
2349 const Type* LoadUSNode::Value(PhaseGVN* phase) const {
2350 Node* mem = in(MemNode::Memory);
2351 Node* value = can_see_stored_value(mem,phase);
2352 if (value != nullptr && value->is_Con() &&
2353 !value->bottom_type()->higher_equal(_type)) {
2354 // If the input to the store does not fit with the load's result type,
2355 // it must be truncated. We can't delay until Ideal call since
2356 // a singleton Value is needed for split_thru_phi optimization.
2357 int con = value->get_int();
2358 return TypeInt::make(con & 0xFFFF);
2359 }
2360 return LoadNode::Value(phase);
2361 }
2362
2363 //--------------------------LoadSNode::Ideal--------------------------------------
2364 //
2365 // If the previous store is to the same address as this load,
2366 // and the value stored was larger than a short, replace this load
2367 // with the value stored truncated to a short. If no truncation is
2368 // needed, the replacement is done in LoadNode::Identity().
2369 //
2370 Node* LoadSNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2371 Node* mem = in(MemNode::Memory);
2372 Node* value = can_see_stored_value(mem,phase);
2373 if (value != nullptr) {
2374 Node* narrow = Compile::narrow_value(T_SHORT, value, _type, phase, false);
2375 if (narrow != value) {
2376 return narrow;
2377 }
2378 }
2379 // Identity call will handle the case where truncation is not needed.
2380 return LoadNode::Ideal(phase, can_reshape);
2381 }
2382
2383 const Type* LoadSNode::Value(PhaseGVN* phase) const {
2384 Node* mem = in(MemNode::Memory);
2385 Node* value = can_see_stored_value(mem,phase);
2386 if (value != nullptr && value->is_Con() &&
2387 !value->bottom_type()->higher_equal(_type)) {
2388 // If the input to the store does not fit with the load's result type,
2389 // it must be truncated. We can't delay until Ideal call since
2390 // a singleton Value is needed for split_thru_phi optimization.
2391 int con = value->get_int();
2392 return TypeInt::make((con << 16) >> 16);
2393 }
2394 return LoadNode::Value(phase);
2395 }
2396
2397 //=============================================================================
2398 //----------------------------LoadKlassNode::make------------------------------
2399 // Polymorphic factory method:
2400 Node* LoadKlassNode::make(PhaseGVN& gvn, Node* mem, Node* adr, const TypePtr* at, const TypeKlassPtr* tk) {
2401 // sanity check the alias category against the created node type
2402 const TypePtr* adr_type = adr->bottom_type()->isa_ptr();
2403 assert(adr_type != nullptr, "expecting TypeKlassPtr");
2404 #ifdef _LP64
2405 if (adr_type->is_ptr_to_narrowklass()) {
2406 assert(UseCompressedClassPointers, "no compressed klasses");
2407 Node* load_klass = gvn.transform(new LoadNKlassNode(mem, adr, at, tk->make_narrowklass(), MemNode::unordered));
2408 return new DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr());
2409 }
2410 #endif
2411 assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
2412 return new LoadKlassNode(mem, adr, at, tk, MemNode::unordered);
2413 }
2414
2415 //------------------------------Value------------------------------------------
2416 const Type* LoadKlassNode::Value(PhaseGVN* phase) const {
2417 return klass_value_common(phase);
2418 }
2419
2420 const Type* LoadNode::klass_value_common(PhaseGVN* phase) const {
2421 // Either input is TOP ==> the result is TOP
2422 const Type *t1 = phase->type( in(MemNode::Memory) );
2423 if (t1 == Type::TOP) return Type::TOP;
2424 Node *adr = in(MemNode::Address);
2425 const Type *t2 = phase->type( adr );
2426 if (t2 == Type::TOP) return Type::TOP;
2427 const TypePtr *tp = t2->is_ptr();
2428 if (TypePtr::above_centerline(tp->ptr()) ||
2429 tp->ptr() == TypePtr::Null) return Type::TOP;
2430
2431 // Return a more precise klass, if possible
2432 const TypeInstPtr *tinst = tp->isa_instptr();
2433 if (tinst != nullptr) {
2434 ciInstanceKlass* ik = tinst->instance_klass();
2435 int offset = tinst->offset();
2436 if (ik == phase->C->env()->Class_klass()
2437 && (offset == java_lang_Class::klass_offset() ||
2438 offset == java_lang_Class::array_klass_offset())) {
2439 // We are loading a special hidden field from a Class mirror object,
2440 // the field which points to the VM's Klass metaobject.
2441 ciType* t = tinst->java_mirror_type();
2442 // java_mirror_type returns non-null for compile-time Class constants.
2443 if (t != nullptr) {
2444 // constant oop => constant klass
2445 if (offset == java_lang_Class::array_klass_offset()) {
2446 if (t->is_void()) {
2447 // We cannot create a void array. Since void is a primitive type return null
2448 // klass. Users of this result need to do a null check on the returned klass.
2449 return TypePtr::NULL_PTR;
2450 }
2451 return TypeKlassPtr::make(ciArrayKlass::make(t), Type::trust_interfaces);
2452 }
2453 if (!t->is_klass()) {
2454 // a primitive Class (e.g., int.class) has null for a klass field
2455 return TypePtr::NULL_PTR;
2456 }
2457 // Fold up the load of the hidden field
2458 return TypeKlassPtr::make(t->as_klass(), Type::trust_interfaces);
2459 }
2460 // non-constant mirror, so we can't tell what's going on
2461 }
2462 if (!tinst->is_loaded())
2463 return _type; // Bail out if not loaded
2464 if (offset == oopDesc::klass_offset_in_bytes()) {
2465 return tinst->as_klass_type(true);
2466 }
2467 }
2468
2469 // Check for loading klass from an array
2470 const TypeAryPtr *tary = tp->isa_aryptr();
2471 if (tary != nullptr &&
2472 tary->offset() == oopDesc::klass_offset_in_bytes()) {
2473 return tary->as_klass_type(true);
2474 }
2475
2476 // Check for loading klass from an array klass
2477 const TypeKlassPtr *tkls = tp->isa_klassptr();
2478 if (tkls != nullptr && !StressReflectiveCode) {
2479 if (!tkls->is_loaded())
2480 return _type; // Bail out if not loaded
2481 if (tkls->isa_aryklassptr() && tkls->is_aryklassptr()->elem()->isa_klassptr() &&
2482 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) {
2483 // // Always returning precise element type is incorrect,
2484 // // e.g., element type could be object and array may contain strings
2485 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
2486
2487 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
2488 // according to the element type's subclassing.
2489 return tkls->is_aryklassptr()->elem()->isa_klassptr()->cast_to_exactness(tkls->klass_is_exact());
2490 }
2491 if (tkls->isa_instklassptr() != nullptr && tkls->klass_is_exact() &&
2492 tkls->offset() == in_bytes(Klass::super_offset())) {
2493 ciKlass* sup = tkls->is_instklassptr()->instance_klass()->super();
2494 // The field is Klass::_super. Return its (constant) value.
2495 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
2496 return sup ? TypeKlassPtr::make(sup, Type::trust_interfaces) : TypePtr::NULL_PTR;
2497 }
2498 }
2499
2500 if (tkls != nullptr && !UseSecondarySupersCache
2501 && tkls->offset() == in_bytes(Klass::secondary_super_cache_offset())) {
2502 // Treat Klass::_secondary_super_cache as a constant when the cache is disabled.
2503 return TypePtr::NULL_PTR;
2504 }
2505
2506 // Bailout case
2507 return LoadNode::Value(phase);
2508 }
2509
2510 //------------------------------Identity---------------------------------------
2511 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
2512 // Also feed through the klass in Allocate(...klass...)._klass.
2513 Node* LoadKlassNode::Identity(PhaseGVN* phase) {
2514 return klass_identity_common(phase);
2515 }
2516
2517 Node* LoadNode::klass_identity_common(PhaseGVN* phase) {
2518 Node* x = LoadNode::Identity(phase);
2519 if (x != this) return x;
2520
2521 // Take apart the address into an oop and offset.
2522 // Return 'this' if we cannot.
2523 Node* adr = in(MemNode::Address);
2524 intptr_t offset = 0;
2525 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2526 if (base == nullptr) return this;
2527 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
2528 if (toop == nullptr) return this;
2529
2530 // Step over potential GC barrier for OopHandle resolve
2531 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
2532 if (bs->is_gc_barrier_node(base)) {
2533 base = bs->step_over_gc_barrier(base);
2534 }
2535
2536 // We can fetch the klass directly through an AllocateNode.
2537 // This works even if the klass is not constant (clone or newArray).
2538 if (offset == oopDesc::klass_offset_in_bytes()) {
2539 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
2540 if (allocated_klass != nullptr) {
2541 return allocated_klass;
2542 }
2543 }
2544
2545 // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*.
2546 // See inline_native_Class_query for occurrences of these patterns.
2547 // Java Example: x.getClass().isAssignableFrom(y)
2548 //
2549 // This improves reflective code, often making the Class
2550 // mirror go completely dead. (Current exception: Class
2551 // mirrors may appear in debug info, but we could clean them out by
2552 // introducing a new debug info operator for Klass.java_mirror).
2553
2554 if (toop->isa_instptr() && toop->is_instptr()->instance_klass() == phase->C->env()->Class_klass()
2555 && offset == java_lang_Class::klass_offset()) {
2556 if (base->is_Load()) {
2557 Node* base2 = base->in(MemNode::Address);
2558 if (base2->is_Load()) { /* direct load of a load which is the OopHandle */
2559 Node* adr2 = base2->in(MemNode::Address);
2560 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2561 if (tkls != nullptr && !tkls->empty()
2562 && (tkls->isa_instklassptr() || tkls->isa_aryklassptr())
2563 && adr2->is_AddP()
2564 ) {
2565 int mirror_field = in_bytes(Klass::java_mirror_offset());
2566 if (tkls->offset() == mirror_field) {
2567 return adr2->in(AddPNode::Base);
2568 }
2569 }
2570 }
2571 }
2572 }
2573
2574 return this;
2575 }
2576
2577 LoadNode* LoadNode::clone_pinned() const {
2578 LoadNode* ld = clone()->as_Load();
2579 ld->_control_dependency = UnknownControl;
2580 return ld;
2581 }
2582
2583
2584 //------------------------------Value------------------------------------------
2585 const Type* LoadNKlassNode::Value(PhaseGVN* phase) const {
2586 const Type *t = klass_value_common(phase);
2587 if (t == Type::TOP)
2588 return t;
2589
2590 return t->make_narrowklass();
2591 }
2592
2593 //------------------------------Identity---------------------------------------
2594 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
2595 // Also feed through the klass in Allocate(...klass...)._klass.
2596 Node* LoadNKlassNode::Identity(PhaseGVN* phase) {
2597 Node *x = klass_identity_common(phase);
2598
2599 const Type *t = phase->type( x );
2600 if( t == Type::TOP ) return x;
2601 if( t->isa_narrowklass()) return x;
2602 assert (!t->isa_narrowoop(), "no narrow oop here");
2603
2604 return phase->transform(new EncodePKlassNode(x, t->make_narrowklass()));
2605 }
2606
2607 //------------------------------Value-----------------------------------------
2608 const Type* LoadRangeNode::Value(PhaseGVN* phase) const {
2609 // Either input is TOP ==> the result is TOP
2610 const Type *t1 = phase->type( in(MemNode::Memory) );
2611 if( t1 == Type::TOP ) return Type::TOP;
2612 Node *adr = in(MemNode::Address);
2613 const Type *t2 = phase->type( adr );
2614 if( t2 == Type::TOP ) return Type::TOP;
2615 const TypePtr *tp = t2->is_ptr();
2616 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
2617 const TypeAryPtr *tap = tp->isa_aryptr();
2618 if( !tap ) return _type;
2619 return tap->size();
2620 }
2621
2622 //-------------------------------Ideal---------------------------------------
2623 // Feed through the length in AllocateArray(...length...)._length.
2624 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2625 Node* p = MemNode::Ideal_common(phase, can_reshape);
2626 if (p) return (p == NodeSentinel) ? nullptr : p;
2627
2628 // Take apart the address into an oop and offset.
2629 // Return 'this' if we cannot.
2630 Node* adr = in(MemNode::Address);
2631 intptr_t offset = 0;
2632 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2633 if (base == nullptr) return nullptr;
2634 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2635 if (tary == nullptr) return nullptr;
2636
2637 // We can fetch the length directly through an AllocateArrayNode.
2638 // This works even if the length is not constant (clone or newArray).
2639 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2640 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base);
2641 if (alloc != nullptr) {
2642 Node* allocated_length = alloc->Ideal_length();
2643 Node* len = alloc->make_ideal_length(tary, phase);
2644 if (allocated_length != len) {
2645 // New CastII improves on this.
2646 return len;
2647 }
2648 }
2649 }
2650
2651 return nullptr;
2652 }
2653
2654 //------------------------------Identity---------------------------------------
2655 // Feed through the length in AllocateArray(...length...)._length.
2656 Node* LoadRangeNode::Identity(PhaseGVN* phase) {
2657 Node* x = LoadINode::Identity(phase);
2658 if (x != this) return x;
2659
2660 // Take apart the address into an oop and offset.
2661 // Return 'this' if we cannot.
2662 Node* adr = in(MemNode::Address);
2663 intptr_t offset = 0;
2664 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2665 if (base == nullptr) return this;
2666 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2667 if (tary == nullptr) return this;
2668
2669 // We can fetch the length directly through an AllocateArrayNode.
2670 // This works even if the length is not constant (clone or newArray).
2671 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2672 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base);
2673 if (alloc != nullptr) {
2674 Node* allocated_length = alloc->Ideal_length();
2675 // Do not allow make_ideal_length to allocate a CastII node.
2676 Node* len = alloc->make_ideal_length(tary, phase, false);
2677 if (allocated_length == len) {
2678 // Return allocated_length only if it would not be improved by a CastII.
2679 return allocated_length;
2680 }
2681 }
2682 }
2683
2684 return this;
2685
2686 }
2687
2688 //=============================================================================
2689 //---------------------------StoreNode::make-----------------------------------
2690 // Polymorphic factory method:
2691 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) {
2692 assert((mo == unordered || mo == release), "unexpected");
2693 Compile* C = gvn.C;
2694 assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2695 ctl != nullptr, "raw memory operations should have control edge");
2696
2697 switch (bt) {
2698 case T_BOOLEAN: val = gvn.transform(new AndINode(val, gvn.intcon(0x1))); // Fall through to T_BYTE case
2699 case T_BYTE: return new StoreBNode(ctl, mem, adr, adr_type, val, mo);
2700 case T_INT: return new StoreINode(ctl, mem, adr, adr_type, val, mo);
2701 case T_CHAR:
2702 case T_SHORT: return new StoreCNode(ctl, mem, adr, adr_type, val, mo);
2703 case T_LONG: return new StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic_access);
2704 case T_FLOAT: return new StoreFNode(ctl, mem, adr, adr_type, val, mo);
2705 case T_DOUBLE: return new StoreDNode(ctl, mem, adr, adr_type, val, mo, require_atomic_access);
2706 case T_METADATA:
2707 case T_ADDRESS:
2708 case T_OBJECT:
2709 #ifdef _LP64
2710 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
2711 val = gvn.transform(new EncodePNode(val, val->bottom_type()->make_narrowoop()));
2712 return new StoreNNode(ctl, mem, adr, adr_type, val, mo);
2713 } else if (adr->bottom_type()->is_ptr_to_narrowklass() ||
2714 (UseCompressedClassPointers && val->bottom_type()->isa_klassptr() &&
2715 adr->bottom_type()->isa_rawptr())) {
2716 val = gvn.transform(new EncodePKlassNode(val, val->bottom_type()->make_narrowklass()));
2717 return new StoreNKlassNode(ctl, mem, adr, adr_type, val, mo);
2718 }
2719 #endif
2720 {
2721 return new StorePNode(ctl, mem, adr, adr_type, val, mo);
2722 }
2723 default:
2724 ShouldNotReachHere();
2725 return (StoreNode*)nullptr;
2726 }
2727 }
2728
2729 //--------------------------bottom_type----------------------------------------
2730 const Type *StoreNode::bottom_type() const {
2731 return Type::MEMORY;
2732 }
2733
2734 //------------------------------hash-------------------------------------------
2735 uint StoreNode::hash() const {
2736 // unroll addition of interesting fields
2737 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2738
2739 // Since they are not commoned, do not hash them:
2740 return NO_HASH;
2741 }
2742
2743 // Link together multiple stores (B/S/C/I) into a longer one.
2744 //
2745 // Example: _store = StoreB[i+3]
2746 //
2747 // RangeCheck[i+0] RangeCheck[i+0]
2748 // StoreB[i+0]
2749 // RangeCheck[i+3] RangeCheck[i+3]
2750 // StoreB[i+1] --> pass: fail:
2751 // StoreB[i+2] StoreI[i+0] StoreB[i+0]
2752 // StoreB[i+3]
2753 //
2754 // The 4 StoreB are merged into a single StoreI node. We have to be careful with RangeCheck[i+1]: before
2755 // the optimization, if this RangeCheck[i+1] fails, then we execute only StoreB[i+0], and then trap. After
2756 // the optimization, the new StoreI[i+0] is on the passing path of RangeCheck[i+3], and StoreB[i+0] on the
2757 // failing path.
2758 //
2759 // Note: For normal array stores, every store at first has a RangeCheck. But they can be removed with:
2760 // - RCE (RangeCheck Elimination): the RangeChecks in the loop are hoisted out and before the loop,
2761 // and possibly no RangeChecks remain between the stores.
2762 // - RangeCheck smearing: the earlier RangeChecks are adjusted such that they cover later RangeChecks,
2763 // and those later RangeChecks can be removed. Example:
2764 //
2765 // RangeCheck[i+0] RangeCheck[i+0] <- before first store
2766 // StoreB[i+0] StoreB[i+0] <- first store
2767 // RangeCheck[i+1] --> smeared --> RangeCheck[i+3] <- only RC between first and last store
2768 // StoreB[i+1] StoreB[i+1] <- second store
2769 // RangeCheck[i+2] --> removed
2770 // StoreB[i+2] StoreB[i+2]
2771 // RangeCheck[i+3] --> removed
2772 // StoreB[i+3] StoreB[i+3] <- last store
2773 //
2774 // Thus, it is a common pattern that between the first and last store in a chain
2775 // of adjacent stores there remains exactly one RangeCheck, located between the
2776 // first and the second store (e.g. RangeCheck[i+3]).
2777 //
2778 class MergePrimitiveStores : public StackObj {
2779 private:
2780 PhaseGVN* const _phase;
2781 StoreNode* const _store;
2782 // State machine with initial state Unknown
2783 // Allowed transitions:
2784 // Unknown -> Const
2785 // Unknown -> Platform
2786 // Unknown -> Reverse
2787 // Unknown -> NotAdjacent
2788 // Const -> Const
2789 // Const -> NotAdjacent
2790 // Platform -> Platform
2791 // Platform -> NotAdjacent
2792 // Reverse -> Reverse
2793 // Reverse -> NotAdjacent
2794 // NotAdjacent -> NotAdjacent
2795 enum ValueOrder : uint8_t {
2796 Unknown, // Initial state
2797 Const, // Input values are const
2798 Platform, // Platform order
2799 Reverse, // Reverse platform order
2800 NotAdjacent // Not adjacent
2801 };
2802 ValueOrder _value_order;
2803
2804 NOT_PRODUCT( const CHeapBitMap &_trace_tags; )
2805
2806 public:
2807 MergePrimitiveStores(PhaseGVN* phase, StoreNode* store) :
2808 _phase(phase), _store(store), _value_order(ValueOrder::Unknown)
2809 NOT_PRODUCT( COMMA _trace_tags(Compile::current()->directive()->trace_merge_stores_tags()) )
2810 {}
2811
2812 StoreNode* run();
2813
2814 private:
2815 bool is_compatible_store(const StoreNode* other_store) const;
2816 bool is_adjacent_pair(const StoreNode* use_store, const StoreNode* def_store) const;
2817 bool is_adjacent_input_pair(const Node* n1, const Node* n2, const int memory_size) const;
2818 static bool is_con_RShift(const Node* n, Node const*& base_out, jint& shift_out, PhaseGVN* phase);
2819 enum CFGStatus { SuccessNoRangeCheck, SuccessWithRangeCheck, Failure };
2820 static CFGStatus cfg_status_for_pair(const StoreNode* use_store, const StoreNode* def_store);
2821
2822 class Status {
2823 private:
2824 StoreNode* _found_store;
2825 bool _found_range_check;
2826
2827 Status(StoreNode* found_store, bool found_range_check)
2828 : _found_store(found_store), _found_range_check(found_range_check) {}
2829
2830 public:
2831 StoreNode* found_store() const { return _found_store; }
2832 bool found_range_check() const { return _found_range_check; }
2833 static Status make_failure() { return Status(nullptr, false); }
2834
2835 static Status make(StoreNode* found_store, const CFGStatus cfg_status) {
2836 if (cfg_status == CFGStatus::Failure) {
2837 return Status::make_failure();
2838 }
2839 return Status(found_store, cfg_status == CFGStatus::SuccessWithRangeCheck);
2840 }
2841
2842 #ifndef PRODUCT
2843 void print_on(outputStream* st) const {
2844 if (_found_store == nullptr) {
2845 st->print_cr("None");
2846 } else {
2847 st->print_cr("Found[%d %s, %s]", _found_store->_idx, _found_store->Name(),
2848 _found_range_check ? "RC" : "no-RC");
2849 }
2850 }
2851 #endif
2852 };
2853
2854 enum ValueOrder find_adjacent_input_value_order(const Node* n1, const Node* n2, const int memory_size) const;
2855 Status find_adjacent_use_store(const StoreNode* def_store) const;
2856 Status find_adjacent_def_store(const StoreNode* use_store) const;
2857 Status find_use_store(const StoreNode* def_store) const;
2858 Status find_def_store(const StoreNode* use_store) const;
2859 Status find_use_store_unidirectional(const StoreNode* def_store) const;
2860 Status find_def_store_unidirectional(const StoreNode* use_store) const;
2861
2862 void collect_merge_list(Node_List& merge_list) const;
2863 Node* make_merged_input_value(const Node_List& merge_list);
2864 StoreNode* make_merged_store(const Node_List& merge_list, Node* merged_input_value);
2865
2866 #ifndef PRODUCT
2867 // Access to TraceMergeStores tags
2868 bool is_trace(TraceMergeStores::Tag tag) const {
2869 return _trace_tags.at(tag);
2870 }
2871
2872 bool is_trace_basic() const {
2873 return is_trace(TraceMergeStores::Tag::BASIC);
2874 }
2875
2876 bool is_trace_pointer_parsing() const {
2877 return is_trace(TraceMergeStores::Tag::POINTER_PARSING);
2878 }
2879
2880 bool is_trace_pointer_aliasing() const {
2881 return is_trace(TraceMergeStores::Tag::POINTER_ALIASING);
2882 }
2883
2884 bool is_trace_pointer_adjacency() const {
2885 return is_trace(TraceMergeStores::Tag::POINTER_ADJACENCY);
2886 }
2887
2888 bool is_trace_success() const {
2889 return is_trace(TraceMergeStores::Tag::SUCCESS);
2890 }
2891 #endif
2892
2893 NOT_PRODUCT( void trace(const Node_List& merge_list, const Node* merged_input_value, const StoreNode* merged_store) const; )
2894 };
2895
2896 StoreNode* MergePrimitiveStores::run() {
2897 // Check for B/S/C/I
2898 int opc = _store->Opcode();
2899 if (opc != Op_StoreB && opc != Op_StoreC && opc != Op_StoreI) {
2900 return nullptr;
2901 }
2902
2903 NOT_PRODUCT( if (is_trace_basic()) { tty->print("[TraceMergeStores] MergePrimitiveStores::run: "); _store->dump(); })
2904
2905 // The _store must be the "last" store in a chain. If we find a use we could merge with
2906 // then that use or a store further down is the "last" store.
2907 Status status_use = find_adjacent_use_store(_store);
2908 NOT_PRODUCT( if (is_trace_basic()) { tty->print("[TraceMergeStores] expect no use: "); status_use.print_on(tty); })
2909 if (status_use.found_store() != nullptr) {
2910 return nullptr;
2911 }
2912
2913 // Check if we can merge with at least one def, so that we have at least 2 stores to merge.
2914 Status status_def = find_adjacent_def_store(_store);
2915 NOT_PRODUCT( if (is_trace_basic()) { tty->print("[TraceMergeStores] expect def: "); status_def.print_on(tty); })
2916 Node* def_store = status_def.found_store();
2917 if (def_store == nullptr) {
2918 return nullptr;
2919 }
2920
2921 // Initialize value order
2922 _value_order = find_adjacent_input_value_order(def_store->in(MemNode::ValueIn),
2923 _store->in(MemNode::ValueIn),
2924 _store->memory_size());
2925 assert(_value_order != ValueOrder::NotAdjacent && _value_order != ValueOrder::Unknown, "Order should be checked");
2926
2927 ResourceMark rm;
2928 Node_List merge_list;
2929 collect_merge_list(merge_list);
2930
2931 Node* merged_input_value = make_merged_input_value(merge_list);
2932 if (merged_input_value == nullptr) { return nullptr; }
2933
2934 StoreNode* merged_store = make_merged_store(merge_list, merged_input_value);
2935
2936 NOT_PRODUCT( if (is_trace_success()) { trace(merge_list, merged_input_value, merged_store); } )
2937
2938 return merged_store;
2939 }
2940
2941 // Check compatibility between _store and other_store.
2942 bool MergePrimitiveStores::is_compatible_store(const StoreNode* other_store) const {
2943 int opc = _store->Opcode();
2944 assert(opc == Op_StoreB || opc == Op_StoreC || opc == Op_StoreI, "precondition");
2945
2946 if (other_store == nullptr ||
2947 _store->Opcode() != other_store->Opcode()) {
2948 return false;
2949 }
2950
2951 return true;
2952 }
2953
2954 bool MergePrimitiveStores::is_adjacent_pair(const StoreNode* use_store, const StoreNode* def_store) const {
2955 if (!is_adjacent_input_pair(def_store->in(MemNode::ValueIn),
2956 use_store->in(MemNode::ValueIn),
2957 def_store->memory_size())) {
2958 return false;
2959 }
2960
2961 ResourceMark rm;
2962 #ifndef PRODUCT
2963 const TraceMemPointer trace(is_trace_pointer_parsing(),
2964 is_trace_pointer_aliasing(),
2965 is_trace_pointer_adjacency(),
2966 true);
2967 #endif
2968 const MemPointer pointer_use(use_store NOT_PRODUCT(COMMA trace));
2969 const MemPointer pointer_def(def_store NOT_PRODUCT(COMMA trace));
2970 return pointer_def.is_adjacent_to_and_before(pointer_use);
2971 }
2972
2973 // Check input values n1 and n2 can be merged and return the value order
2974 MergePrimitiveStores::ValueOrder MergePrimitiveStores::find_adjacent_input_value_order(const Node* n1, const Node* n2,
2975 const int memory_size) const {
2976 // Pattern: [n1 = ConI, n2 = ConI]
2977 if (n1->Opcode() == Op_ConI && n2->Opcode() == Op_ConI) {
2978 return ValueOrder::Const;
2979 }
2980
2981 Node const *base_n2;
2982 jint shift_n2;
2983 if (!is_con_RShift(n2, base_n2, shift_n2, _phase)) {
2984 return ValueOrder::NotAdjacent;
2985 }
2986 Node const *base_n1;
2987 jint shift_n1;
2988 if (!is_con_RShift(n1, base_n1, shift_n1, _phase)) {
2989 return ValueOrder::NotAdjacent;
2990 }
2991
2992 int bits_per_store = memory_size * 8;
2993 if (base_n1 != base_n2 ||
2994 abs(shift_n1 - shift_n2) != bits_per_store ||
2995 shift_n1 % bits_per_store != 0) {
2996 // Values are not adjacent
2997 return ValueOrder::NotAdjacent;
2998 }
2999
3000 // Detect value order
3001 #ifdef VM_LITTLE_ENDIAN
3002 return shift_n1 < shift_n2 ? ValueOrder::Platform // Pattern: [n1 = base >> shift, n2 = base >> (shift + memory_size)]
3003 : ValueOrder::Reverse; // Pattern: [n1 = base >> (shift + memory_size), n2 = base >> shift]
3004 #else
3005 return shift_n1 > shift_n2 ? ValueOrder::Platform // Pattern: [n1 = base >> (shift + memory_size), n2 = base >> shift]
3006 : ValueOrder::Reverse; // Pattern: [n1 = base >> shift, n2 = base >> (shift + memory_size)]
3007 #endif
3008 }
3009
3010 bool MergePrimitiveStores::is_adjacent_input_pair(const Node* n1, const Node* n2, const int memory_size) const {
3011 ValueOrder input_value_order = find_adjacent_input_value_order(n1, n2, memory_size);
3012
3013 switch (input_value_order) {
3014 case ValueOrder::NotAdjacent:
3015 return false;
3016 case ValueOrder::Reverse:
3017 if (memory_size != 1 ||
3018 !Matcher::match_rule_supported(Op_ReverseBytesS) ||
3019 !Matcher::match_rule_supported(Op_ReverseBytesI) ||
3020 !Matcher::match_rule_supported(Op_ReverseBytesL)) {
3021 // ReverseBytes are not supported by platform
3022 return false;
3023 }
3024 // fall-through.
3025 case ValueOrder::Const:
3026 case ValueOrder::Platform:
3027 if (_value_order == ValueOrder::Unknown) {
3028 // Initial state is Unknown, and we find a valid input value order
3029 return true;
3030 }
3031 // The value order can not be changed
3032 return _value_order == input_value_order;
3033 case ValueOrder::Unknown:
3034 default:
3035 ShouldNotReachHere();
3036 }
3037 return false;
3038 }
3039
3040 // Detect pattern: n = base_out >> shift_out
3041 bool MergePrimitiveStores::is_con_RShift(const Node* n, Node const*& base_out, jint& shift_out, PhaseGVN* phase) {
3042 assert(n != nullptr, "precondition");
3043
3044 int opc = n->Opcode();
3045 if (opc == Op_ConvL2I) {
3046 n = n->in(1);
3047 opc = n->Opcode();
3048 }
3049
3050 if ((opc == Op_RShiftI ||
3051 opc == Op_RShiftL ||
3052 opc == Op_URShiftI ||
3053 opc == Op_URShiftL) &&
3054 n->in(2)->is_ConI()) {
3055 base_out = n->in(1);
3056 shift_out = n->in(2)->get_int();
3057 // The shift must be positive:
3058 return shift_out >= 0;
3059 }
3060
3061 if (phase->type(n)->isa_int() != nullptr ||
3062 phase->type(n)->isa_long() != nullptr) {
3063 // (base >> 0)
3064 base_out = n;
3065 shift_out = 0;
3066 return true;
3067 }
3068 return false;
3069 }
3070
3071 // Check if there is nothing between the two stores, except optionally a RangeCheck leading to an uncommon trap.
3072 MergePrimitiveStores::CFGStatus MergePrimitiveStores::cfg_status_for_pair(const StoreNode* use_store, const StoreNode* def_store) {
3073 assert(use_store->in(MemNode::Memory) == def_store, "use-def relationship");
3074
3075 Node* ctrl_use = use_store->in(MemNode::Control);
3076 Node* ctrl_def = def_store->in(MemNode::Control);
3077 if (ctrl_use == nullptr || ctrl_def == nullptr) {
3078 return CFGStatus::Failure;
3079 }
3080
3081 if (ctrl_use == ctrl_def) {
3082 // Same ctrl -> no RangeCheck in between.
3083 // Check: use_store must be the only use of def_store.
3084 if (def_store->outcnt() > 1) {
3085 return CFGStatus::Failure;
3086 }
3087 return CFGStatus::SuccessNoRangeCheck;
3088 }
3089
3090 // Different ctrl -> could have RangeCheck in between.
3091 // Check: 1. def_store only has these uses: use_store and MergeMem for uncommon trap, and
3092 // 2. ctrl separated by RangeCheck.
3093 if (def_store->outcnt() != 2) {
3094 return CFGStatus::Failure; // Cannot have exactly these uses: use_store and MergeMem for uncommon trap.
3095 }
3096 int use_store_out_idx = def_store->raw_out(0) == use_store ? 0 : 1;
3097 Node* merge_mem = def_store->raw_out(1 - use_store_out_idx)->isa_MergeMem();
3098 if (merge_mem == nullptr ||
3099 merge_mem->outcnt() != 1) {
3100 return CFGStatus::Failure; // Does not have MergeMem for uncommon trap.
3101 }
3102 if (!ctrl_use->is_IfProj() ||
3103 !ctrl_use->in(0)->is_RangeCheck() ||
3104 ctrl_use->in(0)->outcnt() != 2) {
3105 return CFGStatus::Failure; // Not RangeCheck.
3106 }
3107 ProjNode* other_proj = ctrl_use->as_IfProj()->other_if_proj();
3108 Node* trap = other_proj->is_uncommon_trap_proj(Deoptimization::Reason_range_check);
3109 if (trap != merge_mem->unique_out() ||
3110 ctrl_use->in(0)->in(0) != ctrl_def) {
3111 return CFGStatus::Failure; // Not RangeCheck with merge_mem leading to uncommon trap.
3112 }
3113
3114 return CFGStatus::SuccessWithRangeCheck;
3115 }
3116
3117 MergePrimitiveStores::Status MergePrimitiveStores::find_adjacent_use_store(const StoreNode* def_store) const {
3118 Status status_use = find_use_store(def_store);
3119 StoreNode* use_store = status_use.found_store();
3120 if (use_store != nullptr && !is_adjacent_pair(use_store, def_store)) {
3121 return Status::make_failure();
3122 }
3123 return status_use;
3124 }
3125
3126 MergePrimitiveStores::Status MergePrimitiveStores::find_adjacent_def_store(const StoreNode* use_store) const {
3127 Status status_def = find_def_store(use_store);
3128 StoreNode* def_store = status_def.found_store();
3129 if (def_store != nullptr && !is_adjacent_pair(use_store, def_store)) {
3130 return Status::make_failure();
3131 }
3132 return status_def;
3133 }
3134
3135 MergePrimitiveStores::Status MergePrimitiveStores::find_use_store(const StoreNode* def_store) const {
3136 Status status_use = find_use_store_unidirectional(def_store);
3137
3138 #ifdef ASSERT
3139 StoreNode* use_store = status_use.found_store();
3140 if (use_store != nullptr) {
3141 Status status_def = find_def_store_unidirectional(use_store);
3142 assert(status_def.found_store() == def_store &&
3143 status_def.found_range_check() == status_use.found_range_check(),
3144 "find_use_store and find_def_store must be symmetric");
3145 }
3146 #endif
3147
3148 return status_use;
3149 }
3150
3151 MergePrimitiveStores::Status MergePrimitiveStores::find_def_store(const StoreNode* use_store) const {
3152 Status status_def = find_def_store_unidirectional(use_store);
3153
3154 #ifdef ASSERT
3155 StoreNode* def_store = status_def.found_store();
3156 if (def_store != nullptr) {
3157 Status status_use = find_use_store_unidirectional(def_store);
3158 assert(status_use.found_store() == use_store &&
3159 status_use.found_range_check() == status_def.found_range_check(),
3160 "find_use_store and find_def_store must be symmetric");
3161 }
3162 #endif
3163
3164 return status_def;
3165 }
3166
3167 MergePrimitiveStores::Status MergePrimitiveStores::find_use_store_unidirectional(const StoreNode* def_store) const {
3168 assert(is_compatible_store(def_store), "precondition: must be compatible with _store");
3169
3170 for (DUIterator_Fast imax, i = def_store->fast_outs(imax); i < imax; i++) {
3171 StoreNode* use_store = def_store->fast_out(i)->isa_Store();
3172 if (is_compatible_store(use_store)) {
3173 return Status::make(use_store, cfg_status_for_pair(use_store, def_store));
3174 }
3175 }
3176
3177 return Status::make_failure();
3178 }
3179
3180 MergePrimitiveStores::Status MergePrimitiveStores::find_def_store_unidirectional(const StoreNode* use_store) const {
3181 assert(is_compatible_store(use_store), "precondition: must be compatible with _store");
3182
3183 StoreNode* def_store = use_store->in(MemNode::Memory)->isa_Store();
3184 if (!is_compatible_store(def_store)) {
3185 return Status::make_failure();
3186 }
3187
3188 return Status::make(def_store, cfg_status_for_pair(use_store, def_store));
3189 }
3190
3191 void MergePrimitiveStores::collect_merge_list(Node_List& merge_list) const {
3192 // The merged store can be at most 8 bytes.
3193 const uint merge_list_max_size = 8 / _store->memory_size();
3194 assert(merge_list_max_size >= 2 &&
3195 merge_list_max_size <= 8 &&
3196 is_power_of_2(merge_list_max_size),
3197 "must be 2, 4 or 8");
3198
3199 // Traverse up the chain of adjacent def stores.
3200 StoreNode* current = _store;
3201 merge_list.push(current);
3202 while (current != nullptr && merge_list.size() < merge_list_max_size) {
3203 Status status = find_adjacent_def_store(current);
3204 NOT_PRODUCT( if (is_trace_basic()) { tty->print("[TraceMergeStores] find def: "); status.print_on(tty); })
3205
3206 current = status.found_store();
3207 if (current != nullptr) {
3208 merge_list.push(current);
3209
3210 // We can have at most one RangeCheck.
3211 if (status.found_range_check()) {
3212 NOT_PRODUCT( if (is_trace_basic()) { tty->print_cr("[TraceMergeStores] found RangeCheck, stop traversal."); })
3213 break;
3214 }
3215 }
3216 }
3217
3218 NOT_PRODUCT( if (is_trace_basic()) { tty->print_cr("[TraceMergeStores] found:"); merge_list.dump(); })
3219
3220 // Truncate the merge_list to a power of 2.
3221 const uint pow2size = round_down_power_of_2(merge_list.size());
3222 assert(pow2size >= 2, "must be merging at least 2 stores");
3223 while (merge_list.size() > pow2size) { merge_list.pop(); }
3224
3225 NOT_PRODUCT( if (is_trace_basic()) { tty->print_cr("[TraceMergeStores] truncated:"); merge_list.dump(); })
3226 }
3227
3228 // Merge the input values of the smaller stores to a single larger input value.
3229 Node* MergePrimitiveStores::make_merged_input_value(const Node_List& merge_list) {
3230 int new_memory_size = _store->memory_size() * merge_list.size();
3231 Node* first = merge_list.at(merge_list.size()-1);
3232 Node* merged_input_value = nullptr;
3233 if (_store->in(MemNode::ValueIn)->Opcode() == Op_ConI) {
3234 assert(_value_order == ValueOrder::Const, "must match");
3235 // Pattern: [ConI, ConI, ...] -> new constant
3236 jlong con = 0;
3237 jlong bits_per_store = _store->memory_size() * 8;
3238 jlong mask = (((jlong)1) << bits_per_store) - 1;
3239 for (uint i = 0; i < merge_list.size(); i++) {
3240 jlong con_i = merge_list.at(i)->in(MemNode::ValueIn)->get_int();
3241 #ifdef VM_LITTLE_ENDIAN
3242 con = con << bits_per_store;
3243 con = con | (mask & con_i);
3244 #else // VM_LITTLE_ENDIAN
3245 con_i = (mask & con_i) << (i * bits_per_store);
3246 con = con | con_i;
3247 #endif // VM_LITTLE_ENDIAN
3248 }
3249 merged_input_value = _phase->longcon(con);
3250 } else {
3251 assert(_value_order == ValueOrder::Platform || _value_order == ValueOrder::Reverse, "must match");
3252 // Pattern: [base >> 24, base >> 16, base >> 8, base] -> base
3253 // | |
3254 // _store first
3255 //
3256 Node* hi = _store->in(MemNode::ValueIn);
3257 Node* lo = first->in(MemNode::ValueIn);
3258 #ifndef VM_LITTLE_ENDIAN
3259 // `_store` and `first` are swapped in the diagram above
3260 swap(hi, lo);
3261 #endif // !VM_LITTLE_ENDIAN
3262 if (_value_order == ValueOrder::Reverse) {
3263 swap(hi, lo);
3264 }
3265 Node const* hi_base;
3266 jint hi_shift;
3267 merged_input_value = lo;
3268 bool is_true = is_con_RShift(hi, hi_base, hi_shift, _phase);
3269 assert(is_true, "must detect con RShift");
3270 if (merged_input_value != hi_base && merged_input_value->Opcode() == Op_ConvL2I) {
3271 // look through
3272 merged_input_value = merged_input_value->in(1);
3273 }
3274 if (merged_input_value != hi_base) {
3275 // merged_input_value is not the base
3276 return nullptr;
3277 }
3278 }
3279
3280 if (_phase->type(merged_input_value)->isa_long() != nullptr && new_memory_size <= 4) {
3281 // Example:
3282 //
3283 // long base = ...;
3284 // a[0] = (byte)(base >> 0);
3285 // a[1] = (byte)(base >> 8);
3286 //
3287 merged_input_value = _phase->transform(new ConvL2INode(merged_input_value));
3288 }
3289
3290 assert((_phase->type(merged_input_value)->isa_int() != nullptr && new_memory_size <= 4) ||
3291 (_phase->type(merged_input_value)->isa_long() != nullptr && new_memory_size == 8),
3292 "merged_input_value is either int or long, and new_memory_size is small enough");
3293
3294 if (_value_order == ValueOrder::Reverse) {
3295 assert(_store->memory_size() == 1, "only implemented for bytes");
3296 if (new_memory_size == 8) {
3297 merged_input_value = _phase->transform(new ReverseBytesLNode(merged_input_value));
3298 } else if (new_memory_size == 4) {
3299 merged_input_value = _phase->transform(new ReverseBytesINode(merged_input_value));
3300 } else {
3301 assert(new_memory_size == 2, "sanity check");
3302 merged_input_value = _phase->transform(new ReverseBytesSNode(merged_input_value));
3303 }
3304 }
3305 return merged_input_value;
3306 }
3307
3308 // //
3309 // first_ctrl first_mem first_adr first_ctrl first_mem first_adr //
3310 // | | | | | | //
3311 // | | | | +---------------+ | //
3312 // | | | | | | | //
3313 // | | +---------+ | | +---------------+ //
3314 // | | | | | | | | //
3315 // +--------------+ | | v1 +------------------------------+ | | v1 //
3316 // | | | | | | | | | | | | //
3317 // RangeCheck first_store RangeCheck | | first_store //
3318 // | | | | | | | //
3319 // last_ctrl | +----> unc_trap last_ctrl | | +----> unc_trap //
3320 // | | ===> | | | //
3321 // +--------------+ | a2 v2 | | | //
3322 // | | | | | | | | //
3323 // | second_store | | | //
3324 // | | | | | [v1 v2 ... vn] //
3325 // ... ... | | | | //
3326 // | | | | | v //
3327 // +--------------+ | an vn +--------------+ | | merged_input_value //
3328 // | | | | | | | | //
3329 // last_store (= _store) merged_store //
3330 // //
3331 StoreNode* MergePrimitiveStores::make_merged_store(const Node_List& merge_list, Node* merged_input_value) {
3332 Node* first_store = merge_list.at(merge_list.size()-1);
3333 Node* last_ctrl = _store->in(MemNode::Control); // after (optional) RangeCheck
3334 Node* first_mem = first_store->in(MemNode::Memory);
3335 Node* first_adr = first_store->in(MemNode::Address);
3336
3337 const TypePtr* new_adr_type = _store->adr_type();
3338
3339 int new_memory_size = _store->memory_size() * merge_list.size();
3340 BasicType bt = T_ILLEGAL;
3341 switch (new_memory_size) {
3342 case 2: bt = T_SHORT; break;
3343 case 4: bt = T_INT; break;
3344 case 8: bt = T_LONG; break;
3345 }
3346
3347 StoreNode* merged_store = StoreNode::make(*_phase, last_ctrl, first_mem, first_adr,
3348 new_adr_type, merged_input_value, bt, MemNode::unordered);
3349
3350 // Marking the store mismatched is sufficient to prevent reordering, since array stores
3351 // are all on the same slice. Hence, we need no barriers.
3352 merged_store->set_mismatched_access();
3353
3354 // Constants above may now also be be packed -> put candidate on worklist
3355 _phase->is_IterGVN()->_worklist.push(first_mem);
3356
3357 return merged_store;
3358 }
3359
3360 #ifndef PRODUCT
3361 void MergePrimitiveStores::trace(const Node_List& merge_list, const Node* merged_input_value, const StoreNode* merged_store) const {
3362 stringStream ss;
3363 ss.print_cr("[TraceMergeStores]: Replace");
3364 for (int i = (int)merge_list.size() - 1; i >= 0; i--) {
3365 merge_list.at(i)->dump("\n", false, &ss);
3366 }
3367 ss.print_cr("[TraceMergeStores]: with");
3368 merged_input_value->dump("\n", false, &ss);
3369 merged_store->dump("\n", false, &ss);
3370 tty->print("%s", ss.as_string());
3371 }
3372 #endif
3373
3374 //------------------------------Ideal------------------------------------------
3375 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
3376 // When a store immediately follows a relevant allocation/initialization,
3377 // try to capture it into the initialization, or hoist it above.
3378 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3379 Node* p = MemNode::Ideal_common(phase, can_reshape);
3380 if (p) return (p == NodeSentinel) ? nullptr : p;
3381
3382 Node* mem = in(MemNode::Memory);
3383 Node* address = in(MemNode::Address);
3384 Node* value = in(MemNode::ValueIn);
3385 // Back-to-back stores to same address? Fold em up. Generally
3386 // unsafe if I have intervening uses.
3387 {
3388 Node* st = mem;
3389 // If Store 'st' has more than one use, we cannot fold 'st' away.
3390 // For example, 'st' might be the final state at a conditional
3391 // return. Or, 'st' might be used by some node which is live at
3392 // the same time 'st' is live, which might be unschedulable. So,
3393 // require exactly ONE user until such time as we clone 'mem' for
3394 // each of 'mem's uses (thus making the exactly-1-user-rule hold
3395 // true).
3396 while (st->is_Store() && st->outcnt() == 1) {
3397 // Looking at a dead closed cycle of memory?
3398 assert(st != st->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
3399 assert(Opcode() == st->Opcode() ||
3400 st->Opcode() == Op_StoreVector ||
3401 Opcode() == Op_StoreVector ||
3402 st->Opcode() == Op_StoreVectorScatter ||
3403 Opcode() == Op_StoreVectorScatter ||
3404 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw ||
3405 (Opcode() == Op_StoreL && st->Opcode() == Op_StoreI) || // expanded ClearArrayNode
3406 (Opcode() == Op_StoreI && st->Opcode() == Op_StoreL) || // initialization by arraycopy
3407 (is_mismatched_access() || st->as_Store()->is_mismatched_access()),
3408 "no mismatched stores, except on raw memory: %s %s", NodeClassNames[Opcode()], NodeClassNames[st->Opcode()]);
3409
3410 if (st->in(MemNode::Address)->eqv_uncast(address) &&
3411 st->as_Store()->memory_size() <= this->memory_size()) {
3412 Node* use = st->raw_out(0);
3413 if (phase->is_IterGVN()) {
3414 phase->is_IterGVN()->rehash_node_delayed(use);
3415 }
3416 // It's OK to do this in the parser, since DU info is always accurate,
3417 // and the parser always refers to nodes via SafePointNode maps.
3418 use->set_req_X(MemNode::Memory, st->in(MemNode::Memory), phase);
3419 return this;
3420 }
3421 st = st->in(MemNode::Memory);
3422 }
3423 }
3424
3425
3426 // Capture an unaliased, unconditional, simple store into an initializer.
3427 // Or, if it is independent of the allocation, hoist it above the allocation.
3428 if (ReduceFieldZeroing && /*can_reshape &&*/
3429 mem->is_Proj() && mem->in(0)->is_Initialize()) {
3430 InitializeNode* init = mem->in(0)->as_Initialize();
3431 intptr_t offset = init->can_capture_store(this, phase, can_reshape);
3432 if (offset > 0) {
3433 Node* moved = init->capture_store(this, offset, phase, can_reshape);
3434 // If the InitializeNode captured me, it made a raw copy of me,
3435 // and I need to disappear.
3436 if (moved != nullptr) {
3437 // %%% hack to ensure that Ideal returns a new node:
3438 mem = MergeMemNode::make(mem);
3439 return mem; // fold me away
3440 }
3441 }
3442 }
3443
3444 // Fold reinterpret cast into memory operation:
3445 // StoreX mem (MoveY2X v) => StoreY mem v
3446 if (value->is_Move()) {
3447 const Type* vt = value->in(1)->bottom_type();
3448 if (has_reinterpret_variant(vt)) {
3449 if (phase->C->post_loop_opts_phase()) {
3450 return convert_to_reinterpret_store(*phase, value->in(1), vt);
3451 } else {
3452 phase->C->record_for_post_loop_opts_igvn(this); // attempt the transformation once loop opts are over
3453 }
3454 }
3455 }
3456
3457 if (MergeStores && UseUnalignedAccesses) {
3458 if (phase->C->merge_stores_phase()) {
3459 MergePrimitiveStores merge(phase, this);
3460 Node* progress = merge.run();
3461 if (progress != nullptr) { return progress; }
3462 } else {
3463 // We need to wait with merging stores until RangeCheck smearing has removed the RangeChecks during
3464 // the post loops IGVN phase. If we do it earlier, then there may still be some RangeChecks between
3465 // the stores, and we merge the wrong sequence of stores.
3466 // Example:
3467 // StoreI RangeCheck StoreI StoreI RangeCheck StoreI
3468 // Apply MergeStores:
3469 // StoreI RangeCheck [ StoreL ] RangeCheck StoreI
3470 // Remove more RangeChecks:
3471 // StoreI [ StoreL ] StoreI
3472 // But now it would have been better to do this instead:
3473 // [ StoreL ] [ StoreL ]
3474 phase->C->record_for_merge_stores_igvn(this);
3475 }
3476 }
3477
3478 return nullptr; // No further progress
3479 }
3480
3481 //------------------------------Value-----------------------------------------
3482 const Type* StoreNode::Value(PhaseGVN* phase) const {
3483 // Either input is TOP ==> the result is TOP
3484 const Type *t1 = phase->type( in(MemNode::Memory) );
3485 if( t1 == Type::TOP ) return Type::TOP;
3486 const Type *t2 = phase->type( in(MemNode::Address) );
3487 if( t2 == Type::TOP ) return Type::TOP;
3488 const Type *t3 = phase->type( in(MemNode::ValueIn) );
3489 if( t3 == Type::TOP ) return Type::TOP;
3490 return Type::MEMORY;
3491 }
3492
3493 //------------------------------Identity---------------------------------------
3494 // Remove redundant stores:
3495 // Store(m, p, Load(m, p)) changes to m.
3496 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
3497 Node* StoreNode::Identity(PhaseGVN* phase) {
3498 Node* mem = in(MemNode::Memory);
3499 Node* adr = in(MemNode::Address);
3500 Node* val = in(MemNode::ValueIn);
3501
3502 Node* result = this;
3503
3504 // Load then Store? Then the Store is useless
3505 if (val->is_Load() &&
3506 val->in(MemNode::Address)->eqv_uncast(adr) &&
3507 val->in(MemNode::Memory )->eqv_uncast(mem) &&
3508 val->as_Load()->store_Opcode() == Opcode()) {
3509 // Ensure vector type is the same
3510 if (!is_StoreVector() || (mem->is_LoadVector() && as_StoreVector()->vect_type() == mem->as_LoadVector()->vect_type())) {
3511 result = mem;
3512 }
3513 }
3514
3515 // Two stores in a row of the same value?
3516 if (result == this &&
3517 mem->is_Store() &&
3518 mem->in(MemNode::Address)->eqv_uncast(adr) &&
3519 mem->in(MemNode::ValueIn)->eqv_uncast(val) &&
3520 mem->Opcode() == Opcode()) {
3521 if (!is_StoreVector()) {
3522 result = mem;
3523 } else {
3524 const StoreVectorNode* store_vector = as_StoreVector();
3525 const StoreVectorNode* mem_vector = mem->as_StoreVector();
3526 const Node* store_indices = store_vector->indices();
3527 const Node* mem_indices = mem_vector->indices();
3528 const Node* store_mask = store_vector->mask();
3529 const Node* mem_mask = mem_vector->mask();
3530 // Ensure types, indices, and masks match
3531 if (store_vector->vect_type() == mem_vector->vect_type() &&
3532 ((store_indices == nullptr) == (mem_indices == nullptr) &&
3533 (store_indices == nullptr || store_indices->eqv_uncast(mem_indices))) &&
3534 ((store_mask == nullptr) == (mem_mask == nullptr) &&
3535 (store_mask == nullptr || store_mask->eqv_uncast(mem_mask)))) {
3536 result = mem;
3537 }
3538 }
3539 }
3540
3541 // Store of zero anywhere into a freshly-allocated object?
3542 // Then the store is useless.
3543 // (It must already have been captured by the InitializeNode.)
3544 if (result == this &&
3545 ReduceFieldZeroing && phase->type(val)->is_zero_type()) {
3546 // a newly allocated object is already all-zeroes everywhere
3547 if (mem->is_Proj() && mem->in(0)->is_Allocate()) {
3548 result = mem;
3549 }
3550
3551 if (result == this) {
3552 // the store may also apply to zero-bits in an earlier object
3553 Node* prev_mem = find_previous_store(phase);
3554 // Steps (a), (b): Walk past independent stores to find an exact match.
3555 if (prev_mem != nullptr) {
3556 Node* prev_val = can_see_stored_value(prev_mem, phase);
3557 if (prev_val != nullptr && prev_val == val) {
3558 // prev_val and val might differ by a cast; it would be good
3559 // to keep the more informative of the two.
3560 result = mem;
3561 }
3562 }
3563 }
3564 }
3565
3566 PhaseIterGVN* igvn = phase->is_IterGVN();
3567 if (result != this && igvn != nullptr) {
3568 MemBarNode* trailing = trailing_membar();
3569 if (trailing != nullptr) {
3570 #ifdef ASSERT
3571 const TypeOopPtr* t_oop = phase->type(in(Address))->isa_oopptr();
3572 assert(t_oop == nullptr || t_oop->is_known_instance_field(), "only for non escaping objects");
3573 #endif
3574 trailing->remove(igvn);
3575 }
3576 }
3577
3578 return result;
3579 }
3580
3581 //------------------------------match_edge-------------------------------------
3582 // Do we Match on this edge index or not? Match only memory & value
3583 uint StoreNode::match_edge(uint idx) const {
3584 return idx == MemNode::Address || idx == MemNode::ValueIn;
3585 }
3586
3587 //------------------------------cmp--------------------------------------------
3588 // Do not common stores up together. They generally have to be split
3589 // back up anyways, so do not bother.
3590 bool StoreNode::cmp( const Node &n ) const {
3591 return (&n == this); // Always fail except on self
3592 }
3593
3594 //------------------------------Ideal_masked_input-----------------------------
3595 // Check for a useless mask before a partial-word store
3596 // (StoreB ... (AndI valIn conIa) )
3597 // If (conIa & mask == mask) this simplifies to
3598 // (StoreB ... (valIn) )
3599 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
3600 Node *val = in(MemNode::ValueIn);
3601 if( val->Opcode() == Op_AndI ) {
3602 const TypeInt *t = phase->type( val->in(2) )->isa_int();
3603 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
3604 set_req_X(MemNode::ValueIn, val->in(1), phase);
3605 return this;
3606 }
3607 }
3608 return nullptr;
3609 }
3610
3611
3612 //------------------------------Ideal_sign_extended_input----------------------
3613 // Check for useless sign-extension before a partial-word store
3614 // (StoreB ... (RShiftI _ (LShiftI _ v conIL) conIR))
3615 // If (conIL == conIR && conIR <= num_rejected_bits) this simplifies to
3616 // (StoreB ... (v))
3617 // If (conIL > conIR) under some conditions, it can be simplified into
3618 // (StoreB ... (LShiftI _ v (conIL - conIR)))
3619 // This case happens when the value of the store was itself a left shift, that
3620 // gets merged into the inner left shift of the sign-extension. For instance,
3621 // if we have
3622 // array_of_shorts[0] = (short)(v << 2)
3623 // We get a structure such as:
3624 // (StoreB ... (RShiftI _ (LShiftI _ (LShiftI _ v 2) 16) 16))
3625 // that is simplified into
3626 // (StoreB ... (RShiftI _ (LShiftI _ v 18) 16)).
3627 // It is thus useful to handle cases where conIL > conIR. But this simplification
3628 // does not always hold. Let's see in which cases it's valid.
3629 //
3630 // Let's assume we have the following 32 bits integer v:
3631 // +----------------------------------+
3632 // | v[0..31] |
3633 // +----------------------------------+
3634 // 31 0
3635 // that will be stuffed in 8 bits byte after a shift left and a shift right of
3636 // potentially different magnitudes.
3637 // We denote num_rejected_bits the number of bits of the discarded part. In this
3638 // case, num_rejected_bits == 24.
3639 //
3640 // Statement (proved further below in case analysis):
3641 // Given:
3642 // - 0 <= conIL < BitsPerJavaInteger (no wrap in shift, enforced by maskShiftAmount)
3643 // - 0 <= conIR < BitsPerJavaInteger (no wrap in shift, enforced by maskShiftAmount)
3644 // - conIL >= conIR
3645 // - num_rejected_bits >= conIR
3646 // Then this form:
3647 // (RShiftI _ (LShiftI _ v conIL) conIR)
3648 // can be replaced with this form:
3649 // (LShiftI _ v (conIL-conIR))
3650 //
3651 // Note: We only have to show that the non-rejected lowest bits (8 bits for byte)
3652 // have to be correct, as the higher bits are rejected / truncated by the store.
3653 //
3654 // The hypotheses
3655 // 0 <= conIL < BitsPerJavaInteger
3656 // 0 <= conIR < BitsPerJavaInteger
3657 // are ensured by maskShiftAmount (called from ::Ideal of shift nodes). Indeed,
3658 // (v << 31) << 2 must be simplified into 0, not into v << 33 (which is equivalent
3659 // to v << 1).
3660 //
3661 //
3662 // If you don't like case analysis, jump after the conclusion.
3663 // ### Case 1 : conIL == conIR
3664 // ###### Case 1.1: conIL == conIR == num_rejected_bits
3665 // If we do the shift left then right by 24 bits, we get:
3666 // after: v << 24
3667 // +---------+------------------------+
3668 // | v[0..7] | 0 |
3669 // +---------+------------------------+
3670 // 31 24 23 0
3671 // after: (v << 24) >> 24
3672 // +------------------------+---------+
3673 // | sign bit | v[0..7] |
3674 // +------------------------+---------+
3675 // 31 8 7 0
3676 // The non-rejected bits (bits kept by the store, that is the 8 lower bits of the
3677 // result) are the same before and after, so, indeed, simplifying is correct.
3678
3679 // ###### Case 1.2: conIL == conIR < num_rejected_bits
3680 // If we do the shift left then right by 22 bits, we get:
3681 // after: v << 22
3682 // +---------+------------------------+
3683 // | v[0..9] | 0 |
3684 // +---------+------------------------+
3685 // 31 22 21 0
3686 // after: (v << 22) >> 22
3687 // +------------------------+---------+
3688 // | sign bit | v[0..9] |
3689 // +------------------------+---------+
3690 // 31 10 9 0
3691 // The non-rejected bits are the 8 lower bits of v. The bits 8 and 9 of v are still
3692 // present in (v << 22) >> 22 but will be dropped by the store. The simplification is
3693 // still correct.
3694
3695 // ###### But! Case 1.3: conIL == conIR > num_rejected_bits
3696 // If we do the shift left then right by 26 bits, we get:
3697 // after: v << 26
3698 // +---------+------------------------+
3699 // | v[0..5] | 0 |
3700 // +---------+------------------------+
3701 // 31 26 25 0
3702 // after: (v << 26) >> 26
3703 // +------------------------+---------+
3704 // | sign bit | v[0..5] |
3705 // +------------------------+---------+
3706 // 31 6 5 0
3707 // The non-rejected bits are made of
3708 // - 0-5 => the bits 0 to 5 of v
3709 // - 6-7 => the sign bit of v[0..5] (that is v[5])
3710 // Simplifying this as v is not correct.
3711 // The condition conIR <= num_rejected_bits is indeed necessary in Case 1
3712 //
3713 // ### Case 2: conIL > conIR
3714 // ###### Case 2.1: num_rejected_bits == conIR
3715 // We take conIL == 26 for this example.
3716 // after: v << 26
3717 // +---------+------------------------+
3718 // | v[0..5] | 0 |
3719 // +---------+------------------------+
3720 // 31 26 25 0
3721 // after: (v << 26) >> 24
3722 // +------------------+---------+-----+
3723 // | sign bit | v[0..5] | 0 |
3724 // +------------------+---------+-----+
3725 // 31 8 7 2 1 0
3726 // The non-rejected bits are the 8 lower ones of (v << conIL - conIR).
3727 // The bits 6 and 7 of v have been thrown away after the shift left.
3728 // The simplification is still correct.
3729 //
3730 // ###### Case 2.2: num_rejected_bits > conIR.
3731 // Let's say conIL == 26 and conIR == 22.
3732 // after: v << 26
3733 // +---------+------------------------+
3734 // | v[0..5] | 0 |
3735 // +---------+------------------------+
3736 // 31 26 25 0
3737 // after: (v << 26) >> 22
3738 // +------------------+---------+-----+
3739 // | sign bit | v[0..5] | 0 |
3740 // +------------------+---------+-----+
3741 // 31 10 9 4 3 0
3742 // The bits non-rejected by the store are exactly the 8 lower ones of (v << (conIL - conIR)):
3743 // - 0-3 => 0
3744 // - 4-7 => bits 0 to 3 of v
3745 // The simplification is still correct.
3746 // The bits 4 and 5 of v are still present in (v << (conIL - conIR)) but they don't
3747 // matter as they are not in the 8 lower bits: they will be cut out by the store.
3748 //
3749 // ###### But! Case 2.3: num_rejected_bits < conIR.
3750 // Let's see that this case is not as easy to simplify.
3751 // Let's say conIL == 28 and conIR == 26.
3752 // after: v << 28
3753 // +---------+------------------------+
3754 // | v[0..3] | 0 |
3755 // +---------+------------------------+
3756 // 31 28 27 0
3757 // after: (v << 28) >> 26
3758 // +------------------+---------+-----+
3759 // | sign bit | v[0..3] | 0 |
3760 // +------------------+---------+-----+
3761 // 31 6 5 2 1 0
3762 // The non-rejected bits are made of
3763 // - 0-1 => 0
3764 // - 2-5 => the bits 0 to 3 of v
3765 // - 6-7 => the sign bit of v[0..3] (that is v[3])
3766 // Simplifying this as (v << 2) is not correct.
3767 // The condition conIR <= num_rejected_bits is indeed necessary in Case 2.
3768 //
3769 // ### Conclusion:
3770 // Our hypotheses are indeed sufficient:
3771 // - 0 <= conIL < BitsPerJavaInteger
3772 // - 0 <= conIR < BitsPerJavaInteger
3773 // - conIL >= conIR
3774 // - num_rejected_bits >= conIR
3775 //
3776 // ### A rationale without case analysis:
3777 // After the shift left, conIL upper bits of v are discarded and conIL lower bit
3778 // zeroes are added. After the shift right, conIR lower bits of the previous result
3779 // are discarded. If conIL >= conIR, we discard only the zeroes we made up during
3780 // the shift left, but if conIL < conIR, then we discard also lower bits of v. But
3781 // the point of the simplification is to get an expression of the form
3782 // (v << (conIL - conIR)). This expression discard only higher bits of v, thus the
3783 // simplification is not correct if conIL < conIR.
3784 //
3785 // Moreover, after the shift right, the higher bit of (v << conIL) is repeated on the
3786 // conIR higher bits of ((v << conIL) >> conIR), it's the sign-extension. If
3787 // conIR > num_rejected_bits, then at least one artificial copy of this sign bit will
3788 // be in the window of the store. Thus ((v << conIL) >> conIR) is not equivalent to
3789 // (v << (conIL-conIR)) if conIR > num_rejected_bits.
3790 //
3791 // We do not treat the case conIL < conIR here since the point of this function is
3792 // to skip sign-extensions (that is conIL == conIR == num_rejected_bits). The need
3793 // of treating conIL > conIR comes from the cases where the sign-extended value is
3794 // also left-shift expression. Computing the sign-extension of a right-shift expression
3795 // doesn't yield a situation such as
3796 // (StoreB ... (RShiftI _ (LShiftI _ v conIL) conIR))
3797 // where conIL < conIR.
3798 Node* StoreNode::Ideal_sign_extended_input(PhaseGVN* phase, int num_rejected_bits) {
3799 Node* shr = in(MemNode::ValueIn);
3800 if (shr->Opcode() == Op_RShiftI) {
3801 const TypeInt* conIR = phase->type(shr->in(2))->isa_int();
3802 if (conIR != nullptr && conIR->is_con() && conIR->get_con() >= 0 && conIR->get_con() < BitsPerJavaInteger && conIR->get_con() <= num_rejected_bits) {
3803 Node* shl = shr->in(1);
3804 if (shl->Opcode() == Op_LShiftI) {
3805 const TypeInt* conIL = phase->type(shl->in(2))->isa_int();
3806 if (conIL != nullptr && conIL->is_con() && conIL->get_con() >= 0 && conIL->get_con() < BitsPerJavaInteger) {
3807 if (conIL->get_con() == conIR->get_con()) {
3808 set_req_X(MemNode::ValueIn, shl->in(1), phase);
3809 return this;
3810 }
3811 if (conIL->get_con() > conIR->get_con()) {
3812 Node* new_shl = phase->transform(new LShiftINode(shl->in(1), phase->intcon(conIL->get_con() - conIR->get_con())));
3813 set_req_X(MemNode::ValueIn, new_shl, phase);
3814 return this;
3815 }
3816 }
3817 }
3818 }
3819 }
3820 return nullptr;
3821 }
3822
3823 //------------------------------value_never_loaded-----------------------------------
3824 // Determine whether there are any possible loads of the value stored.
3825 // For simplicity, we actually check if there are any loads from the
3826 // address stored to, not just for loads of the value stored by this node.
3827 //
3828 bool StoreNode::value_never_loaded(PhaseValues* phase) const {
3829 Node *adr = in(Address);
3830 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
3831 if (adr_oop == nullptr)
3832 return false;
3833 if (!adr_oop->is_known_instance_field())
3834 return false; // if not a distinct instance, there may be aliases of the address
3835 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
3836 Node *use = adr->fast_out(i);
3837 if (use->is_Load() || use->is_LoadStore()) {
3838 return false;
3839 }
3840 }
3841 return true;
3842 }
3843
3844 MemBarNode* StoreNode::trailing_membar() const {
3845 if (is_release()) {
3846 MemBarNode* trailing_mb = nullptr;
3847 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
3848 Node* u = fast_out(i);
3849 if (u->is_MemBar()) {
3850 if (u->as_MemBar()->trailing_store()) {
3851 assert(u->Opcode() == Op_MemBarVolatile, "");
3852 assert(trailing_mb == nullptr, "only one");
3853 trailing_mb = u->as_MemBar();
3854 #ifdef ASSERT
3855 Node* leading = u->as_MemBar()->leading_membar();
3856 assert(leading->Opcode() == Op_MemBarRelease, "incorrect membar");
3857 assert(leading->as_MemBar()->leading_store(), "incorrect membar pair");
3858 assert(leading->as_MemBar()->trailing_membar() == u, "incorrect membar pair");
3859 #endif
3860 } else {
3861 assert(u->as_MemBar()->standalone(), "");
3862 }
3863 }
3864 }
3865 return trailing_mb;
3866 }
3867 return nullptr;
3868 }
3869
3870
3871 //=============================================================================
3872 //------------------------------Ideal------------------------------------------
3873 // If the store is from an AND mask that leaves the low bits untouched, then
3874 // we can skip the AND operation. If the store is from a sign-extension
3875 // (a left shift, then right shift) we can skip both.
3876 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
3877 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
3878 if( progress != nullptr ) return progress;
3879
3880 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
3881 if( progress != nullptr ) return progress;
3882
3883 // Finally check the default case
3884 return StoreNode::Ideal(phase, can_reshape);
3885 }
3886
3887 //=============================================================================
3888 //------------------------------Ideal------------------------------------------
3889 // If the store is from an AND mask that leaves the low bits untouched, then
3890 // we can skip the AND operation
3891 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
3892 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
3893 if( progress != nullptr ) return progress;
3894
3895 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
3896 if( progress != nullptr ) return progress;
3897
3898 // Finally check the default case
3899 return StoreNode::Ideal(phase, can_reshape);
3900 }
3901
3902 //=============================================================================
3903 //----------------------------------SCMemProjNode------------------------------
3904 const Type* SCMemProjNode::Value(PhaseGVN* phase) const
3905 {
3906 if (in(0) == nullptr || phase->type(in(0)) == Type::TOP) {
3907 return Type::TOP;
3908 }
3909 return bottom_type();
3910 }
3911
3912 //=============================================================================
3913 //----------------------------------LoadStoreNode------------------------------
3914 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required )
3915 : Node(required),
3916 _type(rt),
3917 _adr_type(at),
3918 _barrier_data(0)
3919 {
3920 init_req(MemNode::Control, c );
3921 init_req(MemNode::Memory , mem);
3922 init_req(MemNode::Address, adr);
3923 init_req(MemNode::ValueIn, val);
3924 init_class_id(Class_LoadStore);
3925 }
3926
3927 //------------------------------Value-----------------------------------------
3928 const Type* LoadStoreNode::Value(PhaseGVN* phase) const {
3929 // Either input is TOP ==> the result is TOP
3930 if (!in(MemNode::Control) || phase->type(in(MemNode::Control)) == Type::TOP) {
3931 return Type::TOP;
3932 }
3933 const Type* t = phase->type(in(MemNode::Memory));
3934 if (t == Type::TOP) {
3935 return Type::TOP;
3936 }
3937 t = phase->type(in(MemNode::Address));
3938 if (t == Type::TOP) {
3939 return Type::TOP;
3940 }
3941 t = phase->type(in(MemNode::ValueIn));
3942 if (t == Type::TOP) {
3943 return Type::TOP;
3944 }
3945 return bottom_type();
3946 }
3947
3948 uint LoadStoreNode::ideal_reg() const {
3949 return _type->ideal_reg();
3950 }
3951
3952 // This method conservatively checks if the result of a LoadStoreNode is
3953 // used, that is, if it returns true, then it is definitely the case that
3954 // the result of the node is not needed.
3955 // For example, GetAndAdd can be matched into a lock_add instead of a
3956 // lock_xadd if the result of LoadStoreNode::result_not_used() is true
3957 bool LoadStoreNode::result_not_used() const {
3958 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
3959 Node *x = fast_out(i);
3960 if (x->Opcode() == Op_SCMemProj) {
3961 continue;
3962 }
3963 if (x->bottom_type() == TypeTuple::MEMBAR &&
3964 !x->is_Call() &&
3965 x->Opcode() != Op_Blackhole) {
3966 continue;
3967 }
3968 return false;
3969 }
3970 return true;
3971 }
3972
3973 MemBarNode* LoadStoreNode::trailing_membar() const {
3974 MemBarNode* trailing = nullptr;
3975 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
3976 Node* u = fast_out(i);
3977 if (u->is_MemBar()) {
3978 if (u->as_MemBar()->trailing_load_store()) {
3979 assert(u->Opcode() == Op_MemBarAcquire, "");
3980 assert(trailing == nullptr, "only one");
3981 trailing = u->as_MemBar();
3982 #ifdef ASSERT
3983 Node* leading = trailing->leading_membar();
3984 assert(support_IRIW_for_not_multiple_copy_atomic_cpu || leading->Opcode() == Op_MemBarRelease, "incorrect membar");
3985 assert(leading->as_MemBar()->leading_load_store(), "incorrect membar pair");
3986 assert(leading->as_MemBar()->trailing_membar() == trailing, "incorrect membar pair");
3987 #endif
3988 } else {
3989 assert(u->as_MemBar()->standalone(), "wrong barrier kind");
3990 }
3991 }
3992 }
3993
3994 return trailing;
3995 }
3996
3997 uint LoadStoreNode::size_of() const { return sizeof(*this); }
3998
3999 //=============================================================================
4000 //----------------------------------LoadStoreConditionalNode--------------------
4001 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, nullptr, TypeInt::BOOL, 5) {
4002 init_req(ExpectedIn, ex );
4003 }
4004
4005 const Type* LoadStoreConditionalNode::Value(PhaseGVN* phase) const {
4006 // Either input is TOP ==> the result is TOP
4007 const Type* t = phase->type(in(ExpectedIn));
4008 if (t == Type::TOP) {
4009 return Type::TOP;
4010 }
4011 return LoadStoreNode::Value(phase);
4012 }
4013
4014 //=============================================================================
4015 //-------------------------------adr_type--------------------------------------
4016 const TypePtr* ClearArrayNode::adr_type() const {
4017 Node *adr = in(3);
4018 if (adr == nullptr) return nullptr; // node is dead
4019 return MemNode::calculate_adr_type(adr->bottom_type());
4020 }
4021
4022 //------------------------------match_edge-------------------------------------
4023 // Do we Match on this edge index or not? Do not match memory
4024 uint ClearArrayNode::match_edge(uint idx) const {
4025 return idx > 1;
4026 }
4027
4028 //------------------------------Identity---------------------------------------
4029 // Clearing a zero length array does nothing
4030 Node* ClearArrayNode::Identity(PhaseGVN* phase) {
4031 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
4032 }
4033
4034 //------------------------------Idealize---------------------------------------
4035 // Clearing a short array is faster with stores
4036 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4037 // Already know this is a large node, do not try to ideal it
4038 if (_is_large) return nullptr;
4039
4040 const int unit = BytesPerLong;
4041 const TypeX* t = phase->type(in(2))->isa_intptr_t();
4042 if (!t) return nullptr;
4043 if (!t->is_con()) return nullptr;
4044 intptr_t raw_count = t->get_con();
4045 intptr_t size = raw_count;
4046 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
4047 // Clearing nothing uses the Identity call.
4048 // Negative clears are possible on dead ClearArrays
4049 // (see jck test stmt114.stmt11402.val).
4050 if (size <= 0 || size % unit != 0) return nullptr;
4051 intptr_t count = size / unit;
4052 // Length too long; communicate this to matchers and assemblers.
4053 // Assemblers are responsible to produce fast hardware clears for it.
4054 if (size > InitArrayShortSize) {
4055 return new ClearArrayNode(in(0), in(1), in(2), in(3), true);
4056 } else if (size > 2 && Matcher::match_rule_supported_vector(Op_ClearArray, 4, T_LONG)) {
4057 return nullptr;
4058 }
4059 if (!IdealizeClearArrayNode) return nullptr;
4060 Node *mem = in(1);
4061 if( phase->type(mem)==Type::TOP ) return nullptr;
4062 Node *adr = in(3);
4063 const Type* at = phase->type(adr);
4064 if( at==Type::TOP ) return nullptr;
4065 const TypePtr* atp = at->isa_ptr();
4066 // adjust atp to be the correct array element address type
4067 if (atp == nullptr) atp = TypePtr::BOTTOM;
4068 else atp = atp->add_offset(Type::OffsetBot);
4069 // Get base for derived pointer purposes
4070 if( adr->Opcode() != Op_AddP ) Unimplemented();
4071 Node *base = adr->in(1);
4072
4073 Node *zero = phase->makecon(TypeLong::ZERO);
4074 Node *off = phase->MakeConX(BytesPerLong);
4075 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
4076 count--;
4077 while( count-- ) {
4078 mem = phase->transform(mem);
4079 adr = phase->transform(new AddPNode(base,adr,off));
4080 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
4081 }
4082 return mem;
4083 }
4084
4085 //----------------------------step_through----------------------------------
4086 // Return allocation input memory edge if it is different instance
4087 // or itself if it is the one we are looking for.
4088 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseValues* phase) {
4089 Node* n = *np;
4090 assert(n->is_ClearArray(), "sanity");
4091 intptr_t offset;
4092 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
4093 // This method is called only before Allocate nodes are expanded
4094 // during macro nodes expansion. Before that ClearArray nodes are
4095 // only generated in PhaseMacroExpand::generate_arraycopy() (before
4096 // Allocate nodes are expanded) which follows allocations.
4097 assert(alloc != nullptr, "should have allocation");
4098 if (alloc->_idx == instance_id) {
4099 // Can not bypass initialization of the instance we are looking for.
4100 return false;
4101 }
4102 // Otherwise skip it.
4103 InitializeNode* init = alloc->initialization();
4104 if (init != nullptr)
4105 *np = init->in(TypeFunc::Memory);
4106 else
4107 *np = alloc->in(TypeFunc::Memory);
4108 return true;
4109 }
4110
4111 //----------------------------clear_memory-------------------------------------
4112 // Generate code to initialize object storage to zero.
4113 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
4114 intptr_t start_offset,
4115 Node* end_offset,
4116 PhaseGVN* phase) {
4117 intptr_t offset = start_offset;
4118
4119 int unit = BytesPerLong;
4120 if ((offset % unit) != 0) {
4121 Node* adr = new AddPNode(dest, dest, phase->MakeConX(offset));
4122 adr = phase->transform(adr);
4123 const TypePtr* atp = TypeRawPtr::BOTTOM;
4124 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
4125 mem = phase->transform(mem);
4126 offset += BytesPerInt;
4127 }
4128 assert((offset % unit) == 0, "");
4129
4130 // Initialize the remaining stuff, if any, with a ClearArray.
4131 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase);
4132 }
4133
4134 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
4135 Node* start_offset,
4136 Node* end_offset,
4137 PhaseGVN* phase) {
4138 if (start_offset == end_offset) {
4139 // nothing to do
4140 return mem;
4141 }
4142
4143 int unit = BytesPerLong;
4144 Node* zbase = start_offset;
4145 Node* zend = end_offset;
4146
4147 // Scale to the unit required by the CPU:
4148 if (!Matcher::init_array_count_is_in_bytes) {
4149 Node* shift = phase->intcon(exact_log2(unit));
4150 zbase = phase->transform(new URShiftXNode(zbase, shift) );
4151 zend = phase->transform(new URShiftXNode(zend, shift) );
4152 }
4153
4154 // Bulk clear double-words
4155 Node* zsize = phase->transform(new SubXNode(zend, zbase) );
4156 Node* adr = phase->transform(new AddPNode(dest, dest, start_offset) );
4157 mem = new ClearArrayNode(ctl, mem, zsize, adr, false);
4158 return phase->transform(mem);
4159 }
4160
4161 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
4162 intptr_t start_offset,
4163 intptr_t end_offset,
4164 PhaseGVN* phase) {
4165 if (start_offset == end_offset) {
4166 // nothing to do
4167 return mem;
4168 }
4169
4170 assert((end_offset % BytesPerInt) == 0, "odd end offset");
4171 intptr_t done_offset = end_offset;
4172 if ((done_offset % BytesPerLong) != 0) {
4173 done_offset -= BytesPerInt;
4174 }
4175 if (done_offset > start_offset) {
4176 mem = clear_memory(ctl, mem, dest,
4177 start_offset, phase->MakeConX(done_offset), phase);
4178 }
4179 if (done_offset < end_offset) { // emit the final 32-bit store
4180 Node* adr = new AddPNode(dest, dest, phase->MakeConX(done_offset));
4181 adr = phase->transform(adr);
4182 const TypePtr* atp = TypeRawPtr::BOTTOM;
4183 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
4184 mem = phase->transform(mem);
4185 done_offset += BytesPerInt;
4186 }
4187 assert(done_offset == end_offset, "");
4188 return mem;
4189 }
4190
4191 //=============================================================================
4192 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
4193 : MultiNode(TypeFunc::Parms + (precedent == nullptr? 0: 1)),
4194 _adr_type(C->get_adr_type(alias_idx)), _kind(Standalone)
4195 #ifdef ASSERT
4196 , _pair_idx(0)
4197 #endif
4198 {
4199 init_class_id(Class_MemBar);
4200 Node* top = C->top();
4201 init_req(TypeFunc::I_O,top);
4202 init_req(TypeFunc::FramePtr,top);
4203 init_req(TypeFunc::ReturnAdr,top);
4204 if (precedent != nullptr)
4205 init_req(TypeFunc::Parms, precedent);
4206 }
4207
4208 //------------------------------cmp--------------------------------------------
4209 uint MemBarNode::hash() const { return NO_HASH; }
4210 bool MemBarNode::cmp( const Node &n ) const {
4211 return (&n == this); // Always fail except on self
4212 }
4213
4214 //------------------------------make-------------------------------------------
4215 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
4216 switch (opcode) {
4217 case Op_MemBarAcquire: return new MemBarAcquireNode(C, atp, pn);
4218 case Op_LoadFence: return new LoadFenceNode(C, atp, pn);
4219 case Op_MemBarRelease: return new MemBarReleaseNode(C, atp, pn);
4220 case Op_StoreFence: return new StoreFenceNode(C, atp, pn);
4221 case Op_MemBarStoreStore: return new MemBarStoreStoreNode(C, atp, pn);
4222 case Op_StoreStoreFence: return new StoreStoreFenceNode(C, atp, pn);
4223 case Op_MemBarAcquireLock: return new MemBarAcquireLockNode(C, atp, pn);
4224 case Op_MemBarReleaseLock: return new MemBarReleaseLockNode(C, atp, pn);
4225 case Op_MemBarVolatile: return new MemBarVolatileNode(C, atp, pn);
4226 case Op_MemBarCPUOrder: return new MemBarCPUOrderNode(C, atp, pn);
4227 case Op_OnSpinWait: return new OnSpinWaitNode(C, atp, pn);
4228 case Op_Initialize: return new InitializeNode(C, atp, pn);
4229 default: ShouldNotReachHere(); return nullptr;
4230 }
4231 }
4232
4233 void MemBarNode::remove(PhaseIterGVN *igvn) {
4234 if (outcnt() != 2) {
4235 assert(Opcode() == Op_Initialize, "Only seen when there are no use of init memory");
4236 assert(outcnt() == 1, "Only control then");
4237 }
4238 if (trailing_store() || trailing_load_store()) {
4239 MemBarNode* leading = leading_membar();
4240 if (leading != nullptr) {
4241 assert(leading->trailing_membar() == this, "inconsistent leading/trailing membars");
4242 leading->remove(igvn);
4243 }
4244 }
4245 if (proj_out_or_null(TypeFunc::Memory) != nullptr) {
4246 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
4247 }
4248 if (proj_out_or_null(TypeFunc::Control) != nullptr) {
4249 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
4250 }
4251 }
4252
4253 //------------------------------Ideal------------------------------------------
4254 // Return a node which is more "ideal" than the current node. Strip out
4255 // control copies
4256 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4257 if (remove_dead_region(phase, can_reshape)) return this;
4258 // Don't bother trying to transform a dead node
4259 if (in(0) && in(0)->is_top()) {
4260 return nullptr;
4261 }
4262
4263 bool progress = false;
4264 // Eliminate volatile MemBars for scalar replaced objects.
4265 if (can_reshape && req() == (Precedent+1)) {
4266 bool eliminate = false;
4267 int opc = Opcode();
4268 if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) {
4269 // Volatile field loads and stores.
4270 Node* my_mem = in(MemBarNode::Precedent);
4271 // The MembarAquire may keep an unused LoadNode alive through the Precedent edge
4272 if ((my_mem != nullptr) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) {
4273 // if the Precedent is a decodeN and its input (a Load) is used at more than one place,
4274 // replace this Precedent (decodeN) with the Load instead.
4275 if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1)) {
4276 Node* load_node = my_mem->in(1);
4277 set_req(MemBarNode::Precedent, load_node);
4278 phase->is_IterGVN()->_worklist.push(my_mem);
4279 my_mem = load_node;
4280 } else {
4281 assert(my_mem->unique_out() == this, "sanity");
4282 assert(!trailing_load_store(), "load store node can't be eliminated");
4283 del_req(Precedent);
4284 phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later
4285 my_mem = nullptr;
4286 }
4287 progress = true;
4288 }
4289 if (my_mem != nullptr && my_mem->is_Mem()) {
4290 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
4291 // Check for scalar replaced object reference.
4292 if( t_oop != nullptr && t_oop->is_known_instance_field() &&
4293 t_oop->offset() != Type::OffsetBot &&
4294 t_oop->offset() != Type::OffsetTop) {
4295 eliminate = true;
4296 }
4297 }
4298 } else if (opc == Op_MemBarRelease || (UseStoreStoreForCtor && opc == Op_MemBarStoreStore)) {
4299 // Final field stores.
4300 Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent));
4301 if ((alloc != nullptr) && alloc->is_Allocate() &&
4302 alloc->as_Allocate()->does_not_escape_thread()) {
4303 // The allocated object does not escape.
4304 eliminate = true;
4305 }
4306 }
4307 if (eliminate) {
4308 // Replace MemBar projections by its inputs.
4309 PhaseIterGVN* igvn = phase->is_IterGVN();
4310 remove(igvn);
4311 // Must return either the original node (now dead) or a new node
4312 // (Do not return a top here, since that would break the uniqueness of top.)
4313 return new ConINode(TypeInt::ZERO);
4314 }
4315 }
4316 return progress ? this : nullptr;
4317 }
4318
4319 //------------------------------Value------------------------------------------
4320 const Type* MemBarNode::Value(PhaseGVN* phase) const {
4321 if( !in(0) ) return Type::TOP;
4322 if( phase->type(in(0)) == Type::TOP )
4323 return Type::TOP;
4324 return TypeTuple::MEMBAR;
4325 }
4326
4327 //------------------------------match------------------------------------------
4328 // Construct projections for memory.
4329 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) {
4330 switch (proj->_con) {
4331 case TypeFunc::Control:
4332 case TypeFunc::Memory:
4333 return new MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
4334 }
4335 ShouldNotReachHere();
4336 return nullptr;
4337 }
4338
4339 void MemBarNode::set_store_pair(MemBarNode* leading, MemBarNode* trailing) {
4340 trailing->_kind = TrailingStore;
4341 leading->_kind = LeadingStore;
4342 #ifdef ASSERT
4343 trailing->_pair_idx = leading->_idx;
4344 leading->_pair_idx = leading->_idx;
4345 #endif
4346 }
4347
4348 void MemBarNode::set_load_store_pair(MemBarNode* leading, MemBarNode* trailing) {
4349 trailing->_kind = TrailingLoadStore;
4350 leading->_kind = LeadingLoadStore;
4351 #ifdef ASSERT
4352 trailing->_pair_idx = leading->_idx;
4353 leading->_pair_idx = leading->_idx;
4354 #endif
4355 }
4356
4357 MemBarNode* MemBarNode::trailing_membar() const {
4358 ResourceMark rm;
4359 Node* trailing = (Node*)this;
4360 VectorSet seen;
4361 Node_Stack multis(0);
4362 do {
4363 Node* c = trailing;
4364 uint i = 0;
4365 do {
4366 trailing = nullptr;
4367 for (; i < c->outcnt(); i++) {
4368 Node* next = c->raw_out(i);
4369 if (next != c && next->is_CFG()) {
4370 if (c->is_MultiBranch()) {
4371 if (multis.node() == c) {
4372 multis.set_index(i+1);
4373 } else {
4374 multis.push(c, i+1);
4375 }
4376 }
4377 trailing = next;
4378 break;
4379 }
4380 }
4381 if (trailing != nullptr && !seen.test_set(trailing->_idx)) {
4382 break;
4383 }
4384 while (multis.size() > 0) {
4385 c = multis.node();
4386 i = multis.index();
4387 if (i < c->req()) {
4388 break;
4389 }
4390 multis.pop();
4391 }
4392 } while (multis.size() > 0);
4393 } while (!trailing->is_MemBar() || !trailing->as_MemBar()->trailing());
4394
4395 MemBarNode* mb = trailing->as_MemBar();
4396 assert((mb->_kind == TrailingStore && _kind == LeadingStore) ||
4397 (mb->_kind == TrailingLoadStore && _kind == LeadingLoadStore), "bad trailing membar");
4398 assert(mb->_pair_idx == _pair_idx, "bad trailing membar");
4399 return mb;
4400 }
4401
4402 MemBarNode* MemBarNode::leading_membar() const {
4403 ResourceMark rm;
4404 VectorSet seen;
4405 Node_Stack regions(0);
4406 Node* leading = in(0);
4407 while (leading != nullptr && (!leading->is_MemBar() || !leading->as_MemBar()->leading())) {
4408 while (leading == nullptr || leading->is_top() || seen.test_set(leading->_idx)) {
4409 leading = nullptr;
4410 while (regions.size() > 0 && leading == nullptr) {
4411 Node* r = regions.node();
4412 uint i = regions.index();
4413 if (i < r->req()) {
4414 leading = r->in(i);
4415 regions.set_index(i+1);
4416 } else {
4417 regions.pop();
4418 }
4419 }
4420 if (leading == nullptr) {
4421 assert(regions.size() == 0, "all paths should have been tried");
4422 return nullptr;
4423 }
4424 }
4425 if (leading->is_Region()) {
4426 regions.push(leading, 2);
4427 leading = leading->in(1);
4428 } else {
4429 leading = leading->in(0);
4430 }
4431 }
4432 #ifdef ASSERT
4433 Unique_Node_List wq;
4434 wq.push((Node*)this);
4435 uint found = 0;
4436 for (uint i = 0; i < wq.size(); i++) {
4437 Node* n = wq.at(i);
4438 if (n->is_Region()) {
4439 for (uint j = 1; j < n->req(); j++) {
4440 Node* in = n->in(j);
4441 if (in != nullptr && !in->is_top()) {
4442 wq.push(in);
4443 }
4444 }
4445 } else {
4446 if (n->is_MemBar() && n->as_MemBar()->leading()) {
4447 assert(n == leading, "consistency check failed");
4448 found++;
4449 } else {
4450 Node* in = n->in(0);
4451 if (in != nullptr && !in->is_top()) {
4452 wq.push(in);
4453 }
4454 }
4455 }
4456 }
4457 assert(found == 1 || (found == 0 && leading == nullptr), "consistency check failed");
4458 #endif
4459 if (leading == nullptr) {
4460 return nullptr;
4461 }
4462 MemBarNode* mb = leading->as_MemBar();
4463 assert((mb->_kind == LeadingStore && _kind == TrailingStore) ||
4464 (mb->_kind == LeadingLoadStore && _kind == TrailingLoadStore), "bad leading membar");
4465 assert(mb->_pair_idx == _pair_idx, "bad leading membar");
4466 return mb;
4467 }
4468
4469
4470 //===========================InitializeNode====================================
4471 // SUMMARY:
4472 // This node acts as a memory barrier on raw memory, after some raw stores.
4473 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
4474 // The Initialize can 'capture' suitably constrained stores as raw inits.
4475 // It can coalesce related raw stores into larger units (called 'tiles').
4476 // It can avoid zeroing new storage for memory units which have raw inits.
4477 // At macro-expansion, it is marked 'complete', and does not optimize further.
4478 //
4479 // EXAMPLE:
4480 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
4481 // ctl = incoming control; mem* = incoming memory
4482 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
4483 // First allocate uninitialized memory and fill in the header:
4484 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
4485 // ctl := alloc.Control; mem* := alloc.Memory*
4486 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
4487 // Then initialize to zero the non-header parts of the raw memory block:
4488 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
4489 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
4490 // After the initialize node executes, the object is ready for service:
4491 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
4492 // Suppose its body is immediately initialized as {1,2}:
4493 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
4494 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
4495 // mem.SLICE(#short[*]) := store2
4496 //
4497 // DETAILS:
4498 // An InitializeNode collects and isolates object initialization after
4499 // an AllocateNode and before the next possible safepoint. As a
4500 // memory barrier (MemBarNode), it keeps critical stores from drifting
4501 // down past any safepoint or any publication of the allocation.
4502 // Before this barrier, a newly-allocated object may have uninitialized bits.
4503 // After this barrier, it may be treated as a real oop, and GC is allowed.
4504 //
4505 // The semantics of the InitializeNode include an implicit zeroing of
4506 // the new object from object header to the end of the object.
4507 // (The object header and end are determined by the AllocateNode.)
4508 //
4509 // Certain stores may be added as direct inputs to the InitializeNode.
4510 // These stores must update raw memory, and they must be to addresses
4511 // derived from the raw address produced by AllocateNode, and with
4512 // a constant offset. They must be ordered by increasing offset.
4513 // The first one is at in(RawStores), the last at in(req()-1).
4514 // Unlike most memory operations, they are not linked in a chain,
4515 // but are displayed in parallel as users of the rawmem output of
4516 // the allocation.
4517 //
4518 // (See comments in InitializeNode::capture_store, which continue
4519 // the example given above.)
4520 //
4521 // When the associated Allocate is macro-expanded, the InitializeNode
4522 // may be rewritten to optimize collected stores. A ClearArrayNode
4523 // may also be created at that point to represent any required zeroing.
4524 // The InitializeNode is then marked 'complete', prohibiting further
4525 // capturing of nearby memory operations.
4526 //
4527 // During macro-expansion, all captured initializations which store
4528 // constant values of 32 bits or smaller are coalesced (if advantageous)
4529 // into larger 'tiles' 32 or 64 bits. This allows an object to be
4530 // initialized in fewer memory operations. Memory words which are
4531 // covered by neither tiles nor non-constant stores are pre-zeroed
4532 // by explicit stores of zero. (The code shape happens to do all
4533 // zeroing first, then all other stores, with both sequences occurring
4534 // in order of ascending offsets.)
4535 //
4536 // Alternatively, code may be inserted between an AllocateNode and its
4537 // InitializeNode, to perform arbitrary initialization of the new object.
4538 // E.g., the object copying intrinsics insert complex data transfers here.
4539 // The initialization must then be marked as 'complete' disable the
4540 // built-in zeroing semantics and the collection of initializing stores.
4541 //
4542 // While an InitializeNode is incomplete, reads from the memory state
4543 // produced by it are optimizable if they match the control edge and
4544 // new oop address associated with the allocation/initialization.
4545 // They return a stored value (if the offset matches) or else zero.
4546 // A write to the memory state, if it matches control and address,
4547 // and if it is to a constant offset, may be 'captured' by the
4548 // InitializeNode. It is cloned as a raw memory operation and rewired
4549 // inside the initialization, to the raw oop produced by the allocation.
4550 // Operations on addresses which are provably distinct (e.g., to
4551 // other AllocateNodes) are allowed to bypass the initialization.
4552 //
4553 // The effect of all this is to consolidate object initialization
4554 // (both arrays and non-arrays, both piecewise and bulk) into a
4555 // single location, where it can be optimized as a unit.
4556 //
4557 // Only stores with an offset less than TrackedInitializationLimit words
4558 // will be considered for capture by an InitializeNode. This puts a
4559 // reasonable limit on the complexity of optimized initializations.
4560
4561 //---------------------------InitializeNode------------------------------------
4562 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
4563 : MemBarNode(C, adr_type, rawoop),
4564 _is_complete(Incomplete), _does_not_escape(false)
4565 {
4566 init_class_id(Class_Initialize);
4567
4568 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
4569 assert(in(RawAddress) == rawoop, "proper init");
4570 // Note: allocation() can be null, for secondary initialization barriers
4571 }
4572
4573 // Since this node is not matched, it will be processed by the
4574 // register allocator. Declare that there are no constraints
4575 // on the allocation of the RawAddress edge.
4576 const RegMask &InitializeNode::in_RegMask(uint idx) const {
4577 // This edge should be set to top, by the set_complete. But be conservative.
4578 if (idx == InitializeNode::RawAddress)
4579 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
4580 return RegMask::Empty;
4581 }
4582
4583 Node* InitializeNode::memory(uint alias_idx) {
4584 Node* mem = in(Memory);
4585 if (mem->is_MergeMem()) {
4586 return mem->as_MergeMem()->memory_at(alias_idx);
4587 } else {
4588 // incoming raw memory is not split
4589 return mem;
4590 }
4591 }
4592
4593 bool InitializeNode::is_non_zero() {
4594 if (is_complete()) return false;
4595 remove_extra_zeroes();
4596 return (req() > RawStores);
4597 }
4598
4599 void InitializeNode::set_complete(PhaseGVN* phase) {
4600 assert(!is_complete(), "caller responsibility");
4601 _is_complete = Complete;
4602
4603 // After this node is complete, it contains a bunch of
4604 // raw-memory initializations. There is no need for
4605 // it to have anything to do with non-raw memory effects.
4606 // Therefore, tell all non-raw users to re-optimize themselves,
4607 // after skipping the memory effects of this initialization.
4608 PhaseIterGVN* igvn = phase->is_IterGVN();
4609 if (igvn) igvn->add_users_to_worklist(this);
4610 }
4611
4612 // convenience function
4613 // return false if the init contains any stores already
4614 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
4615 InitializeNode* init = initialization();
4616 if (init == nullptr || init->is_complete()) return false;
4617 init->remove_extra_zeroes();
4618 // for now, if this allocation has already collected any inits, bail:
4619 if (init->is_non_zero()) return false;
4620 init->set_complete(phase);
4621 return true;
4622 }
4623
4624 void InitializeNode::remove_extra_zeroes() {
4625 if (req() == RawStores) return;
4626 Node* zmem = zero_memory();
4627 uint fill = RawStores;
4628 for (uint i = fill; i < req(); i++) {
4629 Node* n = in(i);
4630 if (n->is_top() || n == zmem) continue; // skip
4631 if (fill < i) set_req(fill, n); // compact
4632 ++fill;
4633 }
4634 // delete any empty spaces created:
4635 while (fill < req()) {
4636 del_req(fill);
4637 }
4638 }
4639
4640 // Helper for remembering which stores go with which offsets.
4641 intptr_t InitializeNode::get_store_offset(Node* st, PhaseValues* phase) {
4642 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
4643 intptr_t offset = -1;
4644 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
4645 phase, offset);
4646 if (base == nullptr) return -1; // something is dead,
4647 if (offset < 0) return -1; // dead, dead
4648 return offset;
4649 }
4650
4651 // Helper for proving that an initialization expression is
4652 // "simple enough" to be folded into an object initialization.
4653 // Attempts to prove that a store's initial value 'n' can be captured
4654 // within the initialization without creating a vicious cycle, such as:
4655 // { Foo p = new Foo(); p.next = p; }
4656 // True for constants and parameters and small combinations thereof.
4657 bool InitializeNode::detect_init_independence(Node* value, PhaseGVN* phase) {
4658 ResourceMark rm;
4659 Unique_Node_List worklist;
4660 worklist.push(value);
4661
4662 uint complexity_limit = 20;
4663 for (uint j = 0; j < worklist.size(); j++) {
4664 if (j >= complexity_limit) {
4665 return false; // Bail out if processed too many nodes
4666 }
4667
4668 Node* n = worklist.at(j);
4669 if (n == nullptr) continue; // (can this really happen?)
4670 if (n->is_Proj()) n = n->in(0);
4671 if (n == this) return false; // found a cycle
4672 if (n->is_Con()) continue;
4673 if (n->is_Start()) continue; // params, etc., are OK
4674 if (n->is_Root()) continue; // even better
4675
4676 // There cannot be any dependency if 'n' is a CFG node that dominates the current allocation
4677 if (n->is_CFG() && phase->is_dominator(n, allocation())) {
4678 continue;
4679 }
4680
4681 Node* ctl = n->in(0);
4682 if (ctl != nullptr && !ctl->is_top()) {
4683 if (ctl->is_Proj()) ctl = ctl->in(0);
4684 if (ctl == this) return false;
4685
4686 // If we already know that the enclosing memory op is pinned right after
4687 // the init, then any control flow that the store has picked up
4688 // must have preceded the init, or else be equal to the init.
4689 // Even after loop optimizations (which might change control edges)
4690 // a store is never pinned *before* the availability of its inputs.
4691 if (!MemNode::all_controls_dominate(n, this)) {
4692 return false; // failed to prove a good control
4693 }
4694 }
4695
4696 // Check data edges for possible dependencies on 'this'.
4697 for (uint i = 1; i < n->req(); i++) {
4698 Node* m = n->in(i);
4699 if (m == nullptr || m == n || m->is_top()) continue;
4700
4701 // Only process data inputs once
4702 worklist.push(m);
4703 }
4704 }
4705
4706 return true;
4707 }
4708
4709 // Here are all the checks a Store must pass before it can be moved into
4710 // an initialization. Returns zero if a check fails.
4711 // On success, returns the (constant) offset to which the store applies,
4712 // within the initialized memory.
4713 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseGVN* phase, bool can_reshape) {
4714 const int FAIL = 0;
4715 if (st->req() != MemNode::ValueIn + 1)
4716 return FAIL; // an inscrutable StoreNode (card mark?)
4717 Node* ctl = st->in(MemNode::Control);
4718 if (!(ctl != nullptr && ctl->is_Proj() && ctl->in(0) == this))
4719 return FAIL; // must be unconditional after the initialization
4720 Node* mem = st->in(MemNode::Memory);
4721 if (!(mem->is_Proj() && mem->in(0) == this))
4722 return FAIL; // must not be preceded by other stores
4723 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
4724 if ((st->Opcode() == Op_StoreP || st->Opcode() == Op_StoreN) &&
4725 !bs->can_initialize_object(st)) {
4726 return FAIL;
4727 }
4728 Node* adr = st->in(MemNode::Address);
4729 intptr_t offset;
4730 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
4731 if (alloc == nullptr)
4732 return FAIL; // inscrutable address
4733 if (alloc != allocation())
4734 return FAIL; // wrong allocation! (store needs to float up)
4735 int size_in_bytes = st->memory_size();
4736 if ((size_in_bytes != 0) && (offset % size_in_bytes) != 0) {
4737 return FAIL; // mismatched access
4738 }
4739 Node* val = st->in(MemNode::ValueIn);
4740
4741 if (!detect_init_independence(val, phase))
4742 return FAIL; // stored value must be 'simple enough'
4743
4744 // The Store can be captured only if nothing after the allocation
4745 // and before the Store is using the memory location that the store
4746 // overwrites.
4747 bool failed = false;
4748 // If is_complete_with_arraycopy() is true the shape of the graph is
4749 // well defined and is safe so no need for extra checks.
4750 if (!is_complete_with_arraycopy()) {
4751 // We are going to look at each use of the memory state following
4752 // the allocation to make sure nothing reads the memory that the
4753 // Store writes.
4754 const TypePtr* t_adr = phase->type(adr)->isa_ptr();
4755 int alias_idx = phase->C->get_alias_index(t_adr);
4756 ResourceMark rm;
4757 Unique_Node_List mems;
4758 mems.push(mem);
4759 Node* unique_merge = nullptr;
4760 for (uint next = 0; next < mems.size(); ++next) {
4761 Node *m = mems.at(next);
4762 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
4763 Node *n = m->fast_out(j);
4764 if (n->outcnt() == 0) {
4765 continue;
4766 }
4767 if (n == st) {
4768 continue;
4769 } else if (n->in(0) != nullptr && n->in(0) != ctl) {
4770 // If the control of this use is different from the control
4771 // of the Store which is right after the InitializeNode then
4772 // this node cannot be between the InitializeNode and the
4773 // Store.
4774 continue;
4775 } else if (n->is_MergeMem()) {
4776 if (n->as_MergeMem()->memory_at(alias_idx) == m) {
4777 // We can hit a MergeMemNode (that will likely go away
4778 // later) that is a direct use of the memory state
4779 // following the InitializeNode on the same slice as the
4780 // store node that we'd like to capture. We need to check
4781 // the uses of the MergeMemNode.
4782 mems.push(n);
4783 }
4784 } else if (n->is_Mem()) {
4785 Node* other_adr = n->in(MemNode::Address);
4786 if (other_adr == adr) {
4787 failed = true;
4788 break;
4789 } else {
4790 const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr();
4791 if (other_t_adr != nullptr) {
4792 int other_alias_idx = phase->C->get_alias_index(other_t_adr);
4793 if (other_alias_idx == alias_idx) {
4794 // A load from the same memory slice as the store right
4795 // after the InitializeNode. We check the control of the
4796 // object/array that is loaded from. If it's the same as
4797 // the store control then we cannot capture the store.
4798 assert(!n->is_Store(), "2 stores to same slice on same control?");
4799 Node* base = other_adr;
4800 assert(base->is_AddP(), "should be addp but is %s", base->Name());
4801 base = base->in(AddPNode::Base);
4802 if (base != nullptr) {
4803 base = base->uncast();
4804 if (base->is_Proj() && base->in(0) == alloc) {
4805 failed = true;
4806 break;
4807 }
4808 }
4809 }
4810 }
4811 }
4812 } else {
4813 failed = true;
4814 break;
4815 }
4816 }
4817 }
4818 }
4819 if (failed) {
4820 if (!can_reshape) {
4821 // We decided we couldn't capture the store during parsing. We
4822 // should try again during the next IGVN once the graph is
4823 // cleaner.
4824 phase->C->record_for_igvn(st);
4825 }
4826 return FAIL;
4827 }
4828
4829 return offset; // success
4830 }
4831
4832 // Find the captured store in(i) which corresponds to the range
4833 // [start..start+size) in the initialized object.
4834 // If there is one, return its index i. If there isn't, return the
4835 // negative of the index where it should be inserted.
4836 // Return 0 if the queried range overlaps an initialization boundary
4837 // or if dead code is encountered.
4838 // If size_in_bytes is zero, do not bother with overlap checks.
4839 int InitializeNode::captured_store_insertion_point(intptr_t start,
4840 int size_in_bytes,
4841 PhaseValues* phase) {
4842 const int FAIL = 0, MAX_STORE = MAX2(BytesPerLong, (int)MaxVectorSize);
4843
4844 if (is_complete())
4845 return FAIL; // arraycopy got here first; punt
4846
4847 assert(allocation() != nullptr, "must be present");
4848
4849 // no negatives, no header fields:
4850 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
4851
4852 // after a certain size, we bail out on tracking all the stores:
4853 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
4854 if (start >= ti_limit) return FAIL;
4855
4856 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
4857 if (i >= limit) return -(int)i; // not found; here is where to put it
4858
4859 Node* st = in(i);
4860 intptr_t st_off = get_store_offset(st, phase);
4861 if (st_off < 0) {
4862 if (st != zero_memory()) {
4863 return FAIL; // bail out if there is dead garbage
4864 }
4865 } else if (st_off > start) {
4866 // ...we are done, since stores are ordered
4867 if (st_off < start + size_in_bytes) {
4868 return FAIL; // the next store overlaps
4869 }
4870 return -(int)i; // not found; here is where to put it
4871 } else if (st_off < start) {
4872 assert(st->as_Store()->memory_size() <= MAX_STORE, "");
4873 if (size_in_bytes != 0 &&
4874 start < st_off + MAX_STORE &&
4875 start < st_off + st->as_Store()->memory_size()) {
4876 return FAIL; // the previous store overlaps
4877 }
4878 } else {
4879 if (size_in_bytes != 0 &&
4880 st->as_Store()->memory_size() != size_in_bytes) {
4881 return FAIL; // mismatched store size
4882 }
4883 return i;
4884 }
4885
4886 ++i;
4887 }
4888 }
4889
4890 // Look for a captured store which initializes at the offset 'start'
4891 // with the given size. If there is no such store, and no other
4892 // initialization interferes, then return zero_memory (the memory
4893 // projection of the AllocateNode).
4894 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
4895 PhaseValues* phase) {
4896 assert(stores_are_sane(phase), "");
4897 int i = captured_store_insertion_point(start, size_in_bytes, phase);
4898 if (i == 0) {
4899 return nullptr; // something is dead
4900 } else if (i < 0) {
4901 return zero_memory(); // just primordial zero bits here
4902 } else {
4903 Node* st = in(i); // here is the store at this position
4904 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
4905 return st;
4906 }
4907 }
4908
4909 // Create, as a raw pointer, an address within my new object at 'offset'.
4910 Node* InitializeNode::make_raw_address(intptr_t offset,
4911 PhaseGVN* phase) {
4912 Node* addr = in(RawAddress);
4913 if (offset != 0) {
4914 Compile* C = phase->C;
4915 addr = phase->transform( new AddPNode(C->top(), addr,
4916 phase->MakeConX(offset)) );
4917 }
4918 return addr;
4919 }
4920
4921 // Clone the given store, converting it into a raw store
4922 // initializing a field or element of my new object.
4923 // Caller is responsible for retiring the original store,
4924 // with subsume_node or the like.
4925 //
4926 // From the example above InitializeNode::InitializeNode,
4927 // here are the old stores to be captured:
4928 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
4929 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
4930 //
4931 // Here is the changed code; note the extra edges on init:
4932 // alloc = (Allocate ...)
4933 // rawoop = alloc.RawAddress
4934 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
4935 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
4936 // init = (Initialize alloc.Control alloc.Memory rawoop
4937 // rawstore1 rawstore2)
4938 //
4939 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
4940 PhaseGVN* phase, bool can_reshape) {
4941 assert(stores_are_sane(phase), "");
4942
4943 if (start < 0) return nullptr;
4944 assert(can_capture_store(st, phase, can_reshape) == start, "sanity");
4945
4946 Compile* C = phase->C;
4947 int size_in_bytes = st->memory_size();
4948 int i = captured_store_insertion_point(start, size_in_bytes, phase);
4949 if (i == 0) return nullptr; // bail out
4950 Node* prev_mem = nullptr; // raw memory for the captured store
4951 if (i > 0) {
4952 prev_mem = in(i); // there is a pre-existing store under this one
4953 set_req(i, C->top()); // temporarily disconnect it
4954 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
4955 } else {
4956 i = -i; // no pre-existing store
4957 prev_mem = zero_memory(); // a slice of the newly allocated object
4958 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
4959 set_req(--i, C->top()); // reuse this edge; it has been folded away
4960 else
4961 ins_req(i, C->top()); // build a new edge
4962 }
4963 Node* new_st = st->clone();
4964 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
4965 new_st->set_req(MemNode::Control, in(Control));
4966 new_st->set_req(MemNode::Memory, prev_mem);
4967 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
4968 bs->eliminate_gc_barrier_data(new_st);
4969 new_st = phase->transform(new_st);
4970
4971 // At this point, new_st might have swallowed a pre-existing store
4972 // at the same offset, or perhaps new_st might have disappeared,
4973 // if it redundantly stored the same value (or zero to fresh memory).
4974
4975 // In any case, wire it in:
4976 PhaseIterGVN* igvn = phase->is_IterGVN();
4977 if (igvn) {
4978 igvn->rehash_node_delayed(this);
4979 }
4980 set_req(i, new_st);
4981
4982 // The caller may now kill the old guy.
4983 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
4984 assert(check_st == new_st || check_st == nullptr, "must be findable");
4985 assert(!is_complete(), "");
4986 return new_st;
4987 }
4988
4989 static bool store_constant(jlong* tiles, int num_tiles,
4990 intptr_t st_off, int st_size,
4991 jlong con) {
4992 if ((st_off & (st_size-1)) != 0)
4993 return false; // strange store offset (assume size==2**N)
4994 address addr = (address)tiles + st_off;
4995 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
4996 switch (st_size) {
4997 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
4998 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
4999 case sizeof(jint): *(jint*) addr = (jint) con; break;
5000 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
5001 default: return false; // strange store size (detect size!=2**N here)
5002 }
5003 return true; // return success to caller
5004 }
5005
5006 // Coalesce subword constants into int constants and possibly
5007 // into long constants. The goal, if the CPU permits,
5008 // is to initialize the object with a small number of 64-bit tiles.
5009 // Also, convert floating-point constants to bit patterns.
5010 // Non-constants are not relevant to this pass.
5011 //
5012 // In terms of the running example on InitializeNode::InitializeNode
5013 // and InitializeNode::capture_store, here is the transformation
5014 // of rawstore1 and rawstore2 into rawstore12:
5015 // alloc = (Allocate ...)
5016 // rawoop = alloc.RawAddress
5017 // tile12 = 0x00010002
5018 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
5019 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
5020 //
5021 void
5022 InitializeNode::coalesce_subword_stores(intptr_t header_size,
5023 Node* size_in_bytes,
5024 PhaseGVN* phase) {
5025 Compile* C = phase->C;
5026
5027 assert(stores_are_sane(phase), "");
5028 // Note: After this pass, they are not completely sane,
5029 // since there may be some overlaps.
5030
5031 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
5032
5033 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
5034 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
5035 size_limit = MIN2(size_limit, ti_limit);
5036 size_limit = align_up(size_limit, BytesPerLong);
5037 int num_tiles = size_limit / BytesPerLong;
5038
5039 // allocate space for the tile map:
5040 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
5041 jlong tiles_buf[small_len];
5042 Node* nodes_buf[small_len];
5043 jlong inits_buf[small_len];
5044 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
5045 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
5046 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
5047 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
5048 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
5049 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
5050 // tiles: exact bitwise model of all primitive constants
5051 // nodes: last constant-storing node subsumed into the tiles model
5052 // inits: which bytes (in each tile) are touched by any initializations
5053
5054 //// Pass A: Fill in the tile model with any relevant stores.
5055
5056 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
5057 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
5058 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
5059 Node* zmem = zero_memory(); // initially zero memory state
5060 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
5061 Node* st = in(i);
5062 intptr_t st_off = get_store_offset(st, phase);
5063
5064 // Figure out the store's offset and constant value:
5065 if (st_off < header_size) continue; //skip (ignore header)
5066 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
5067 int st_size = st->as_Store()->memory_size();
5068 if (st_off + st_size > size_limit) break;
5069
5070 // Record which bytes are touched, whether by constant or not.
5071 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
5072 continue; // skip (strange store size)
5073
5074 const Type* val = phase->type(st->in(MemNode::ValueIn));
5075 if (!val->singleton()) continue; //skip (non-con store)
5076 BasicType type = val->basic_type();
5077
5078 jlong con = 0;
5079 switch (type) {
5080 case T_INT: con = val->is_int()->get_con(); break;
5081 case T_LONG: con = val->is_long()->get_con(); break;
5082 case T_FLOAT: con = jint_cast(val->getf()); break;
5083 case T_DOUBLE: con = jlong_cast(val->getd()); break;
5084 default: continue; //skip (odd store type)
5085 }
5086
5087 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
5088 st->Opcode() == Op_StoreL) {
5089 continue; // This StoreL is already optimal.
5090 }
5091
5092 // Store down the constant.
5093 store_constant(tiles, num_tiles, st_off, st_size, con);
5094
5095 intptr_t j = st_off >> LogBytesPerLong;
5096
5097 if (type == T_INT && st_size == BytesPerInt
5098 && (st_off & BytesPerInt) == BytesPerInt) {
5099 jlong lcon = tiles[j];
5100 if (!Matcher::isSimpleConstant64(lcon) &&
5101 st->Opcode() == Op_StoreI) {
5102 // This StoreI is already optimal by itself.
5103 jint* intcon = (jint*) &tiles[j];
5104 intcon[1] = 0; // undo the store_constant()
5105
5106 // If the previous store is also optimal by itself, back up and
5107 // undo the action of the previous loop iteration... if we can.
5108 // But if we can't, just let the previous half take care of itself.
5109 st = nodes[j];
5110 st_off -= BytesPerInt;
5111 con = intcon[0];
5112 if (con != 0 && st != nullptr && st->Opcode() == Op_StoreI) {
5113 assert(st_off >= header_size, "still ignoring header");
5114 assert(get_store_offset(st, phase) == st_off, "must be");
5115 assert(in(i-1) == zmem, "must be");
5116 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
5117 assert(con == tcon->is_int()->get_con(), "must be");
5118 // Undo the effects of the previous loop trip, which swallowed st:
5119 intcon[0] = 0; // undo store_constant()
5120 set_req(i-1, st); // undo set_req(i, zmem)
5121 nodes[j] = nullptr; // undo nodes[j] = st
5122 --old_subword; // undo ++old_subword
5123 }
5124 continue; // This StoreI is already optimal.
5125 }
5126 }
5127
5128 // This store is not needed.
5129 set_req(i, zmem);
5130 nodes[j] = st; // record for the moment
5131 if (st_size < BytesPerLong) // something has changed
5132 ++old_subword; // includes int/float, but who's counting...
5133 else ++old_long;
5134 }
5135
5136 if ((old_subword + old_long) == 0)
5137 return; // nothing more to do
5138
5139 //// Pass B: Convert any non-zero tiles into optimal constant stores.
5140 // Be sure to insert them before overlapping non-constant stores.
5141 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
5142 for (int j = 0; j < num_tiles; j++) {
5143 jlong con = tiles[j];
5144 jlong init = inits[j];
5145 if (con == 0) continue;
5146 jint con0, con1; // split the constant, address-wise
5147 jint init0, init1; // split the init map, address-wise
5148 { union { jlong con; jint intcon[2]; } u;
5149 u.con = con;
5150 con0 = u.intcon[0];
5151 con1 = u.intcon[1];
5152 u.con = init;
5153 init0 = u.intcon[0];
5154 init1 = u.intcon[1];
5155 }
5156
5157 Node* old = nodes[j];
5158 assert(old != nullptr, "need the prior store");
5159 intptr_t offset = (j * BytesPerLong);
5160
5161 bool split = !Matcher::isSimpleConstant64(con);
5162
5163 if (offset < header_size) {
5164 assert(offset + BytesPerInt >= header_size, "second int counts");
5165 assert(*(jint*)&tiles[j] == 0, "junk in header");
5166 split = true; // only the second word counts
5167 // Example: int a[] = { 42 ... }
5168 } else if (con0 == 0 && init0 == -1) {
5169 split = true; // first word is covered by full inits
5170 // Example: int a[] = { ... foo(), 42 ... }
5171 } else if (con1 == 0 && init1 == -1) {
5172 split = true; // second word is covered by full inits
5173 // Example: int a[] = { ... 42, foo() ... }
5174 }
5175
5176 // Here's a case where init0 is neither 0 nor -1:
5177 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
5178 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
5179 // In this case the tile is not split; it is (jlong)42.
5180 // The big tile is stored down, and then the foo() value is inserted.
5181 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
5182
5183 Node* ctl = old->in(MemNode::Control);
5184 Node* adr = make_raw_address(offset, phase);
5185 const TypePtr* atp = TypeRawPtr::BOTTOM;
5186
5187 // One or two coalesced stores to plop down.
5188 Node* st[2];
5189 intptr_t off[2];
5190 int nst = 0;
5191 if (!split) {
5192 ++new_long;
5193 off[nst] = offset;
5194 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
5195 phase->longcon(con), T_LONG, MemNode::unordered);
5196 } else {
5197 // Omit either if it is a zero.
5198 if (con0 != 0) {
5199 ++new_int;
5200 off[nst] = offset;
5201 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
5202 phase->intcon(con0), T_INT, MemNode::unordered);
5203 }
5204 if (con1 != 0) {
5205 ++new_int;
5206 offset += BytesPerInt;
5207 adr = make_raw_address(offset, phase);
5208 off[nst] = offset;
5209 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
5210 phase->intcon(con1), T_INT, MemNode::unordered);
5211 }
5212 }
5213
5214 // Insert second store first, then the first before the second.
5215 // Insert each one just before any overlapping non-constant stores.
5216 while (nst > 0) {
5217 Node* st1 = st[--nst];
5218 C->copy_node_notes_to(st1, old);
5219 st1 = phase->transform(st1);
5220 offset = off[nst];
5221 assert(offset >= header_size, "do not smash header");
5222 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
5223 guarantee(ins_idx != 0, "must re-insert constant store");
5224 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
5225 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
5226 set_req(--ins_idx, st1);
5227 else
5228 ins_req(ins_idx, st1);
5229 }
5230 }
5231
5232 if (PrintCompilation && WizardMode)
5233 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
5234 old_subword, old_long, new_int, new_long);
5235 if (C->log() != nullptr)
5236 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
5237 old_subword, old_long, new_int, new_long);
5238
5239 // Clean up any remaining occurrences of zmem:
5240 remove_extra_zeroes();
5241 }
5242
5243 // Explore forward from in(start) to find the first fully initialized
5244 // word, and return its offset. Skip groups of subword stores which
5245 // together initialize full words. If in(start) is itself part of a
5246 // fully initialized word, return the offset of in(start). If there
5247 // are no following full-word stores, or if something is fishy, return
5248 // a negative value.
5249 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
5250 int int_map = 0;
5251 intptr_t int_map_off = 0;
5252 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
5253
5254 for (uint i = start, limit = req(); i < limit; i++) {
5255 Node* st = in(i);
5256
5257 intptr_t st_off = get_store_offset(st, phase);
5258 if (st_off < 0) break; // return conservative answer
5259
5260 int st_size = st->as_Store()->memory_size();
5261 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
5262 return st_off; // we found a complete word init
5263 }
5264
5265 // update the map:
5266
5267 intptr_t this_int_off = align_down(st_off, BytesPerInt);
5268 if (this_int_off != int_map_off) {
5269 // reset the map:
5270 int_map = 0;
5271 int_map_off = this_int_off;
5272 }
5273
5274 int subword_off = st_off - this_int_off;
5275 int_map |= right_n_bits(st_size) << subword_off;
5276 if ((int_map & FULL_MAP) == FULL_MAP) {
5277 return this_int_off; // we found a complete word init
5278 }
5279
5280 // Did this store hit or cross the word boundary?
5281 intptr_t next_int_off = align_down(st_off + st_size, BytesPerInt);
5282 if (next_int_off == this_int_off + BytesPerInt) {
5283 // We passed the current int, without fully initializing it.
5284 int_map_off = next_int_off;
5285 int_map >>= BytesPerInt;
5286 } else if (next_int_off > this_int_off + BytesPerInt) {
5287 // We passed the current and next int.
5288 return this_int_off + BytesPerInt;
5289 }
5290 }
5291
5292 return -1;
5293 }
5294
5295
5296 // Called when the associated AllocateNode is expanded into CFG.
5297 // At this point, we may perform additional optimizations.
5298 // Linearize the stores by ascending offset, to make memory
5299 // activity as coherent as possible.
5300 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
5301 intptr_t header_size,
5302 Node* size_in_bytes,
5303 PhaseIterGVN* phase) {
5304 assert(!is_complete(), "not already complete");
5305 assert(stores_are_sane(phase), "");
5306 assert(allocation() != nullptr, "must be present");
5307
5308 remove_extra_zeroes();
5309
5310 if (ReduceFieldZeroing || ReduceBulkZeroing)
5311 // reduce instruction count for common initialization patterns
5312 coalesce_subword_stores(header_size, size_in_bytes, phase);
5313
5314 Node* zmem = zero_memory(); // initially zero memory state
5315 Node* inits = zmem; // accumulating a linearized chain of inits
5316 #ifdef ASSERT
5317 intptr_t first_offset = allocation()->minimum_header_size();
5318 intptr_t last_init_off = first_offset; // previous init offset
5319 intptr_t last_init_end = first_offset; // previous init offset+size
5320 intptr_t last_tile_end = first_offset; // previous tile offset+size
5321 #endif
5322 intptr_t zeroes_done = header_size;
5323
5324 bool do_zeroing = true; // we might give up if inits are very sparse
5325 int big_init_gaps = 0; // how many large gaps have we seen?
5326
5327 if (UseTLAB && ZeroTLAB) do_zeroing = false;
5328 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
5329
5330 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
5331 Node* st = in(i);
5332 intptr_t st_off = get_store_offset(st, phase);
5333 if (st_off < 0)
5334 break; // unknown junk in the inits
5335 if (st->in(MemNode::Memory) != zmem)
5336 break; // complicated store chains somehow in list
5337
5338 int st_size = st->as_Store()->memory_size();
5339 intptr_t next_init_off = st_off + st_size;
5340
5341 if (do_zeroing && zeroes_done < next_init_off) {
5342 // See if this store needs a zero before it or under it.
5343 intptr_t zeroes_needed = st_off;
5344
5345 if (st_size < BytesPerInt) {
5346 // Look for subword stores which only partially initialize words.
5347 // If we find some, we must lay down some word-level zeroes first,
5348 // underneath the subword stores.
5349 //
5350 // Examples:
5351 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
5352 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
5353 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
5354 //
5355 // Note: coalesce_subword_stores may have already done this,
5356 // if it was prompted by constant non-zero subword initializers.
5357 // But this case can still arise with non-constant stores.
5358
5359 intptr_t next_full_store = find_next_fullword_store(i, phase);
5360
5361 // In the examples above:
5362 // in(i) p q r s x y z
5363 // st_off 12 13 14 15 12 13 14
5364 // st_size 1 1 1 1 1 1 1
5365 // next_full_s. 12 16 16 16 16 16 16
5366 // z's_done 12 16 16 16 12 16 12
5367 // z's_needed 12 16 16 16 16 16 16
5368 // zsize 0 0 0 0 4 0 4
5369 if (next_full_store < 0) {
5370 // Conservative tack: Zero to end of current word.
5371 zeroes_needed = align_up(zeroes_needed, BytesPerInt);
5372 } else {
5373 // Zero to beginning of next fully initialized word.
5374 // Or, don't zero at all, if we are already in that word.
5375 assert(next_full_store >= zeroes_needed, "must go forward");
5376 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
5377 zeroes_needed = next_full_store;
5378 }
5379 }
5380
5381 if (zeroes_needed > zeroes_done) {
5382 intptr_t zsize = zeroes_needed - zeroes_done;
5383 // Do some incremental zeroing on rawmem, in parallel with inits.
5384 zeroes_done = align_down(zeroes_done, BytesPerInt);
5385 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
5386 zeroes_done, zeroes_needed,
5387 phase);
5388 zeroes_done = zeroes_needed;
5389 if (zsize > InitArrayShortSize && ++big_init_gaps > 2)
5390 do_zeroing = false; // leave the hole, next time
5391 }
5392 }
5393
5394 // Collect the store and move on:
5395 phase->replace_input_of(st, MemNode::Memory, inits);
5396 inits = st; // put it on the linearized chain
5397 set_req(i, zmem); // unhook from previous position
5398
5399 if (zeroes_done == st_off)
5400 zeroes_done = next_init_off;
5401
5402 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
5403
5404 #ifdef ASSERT
5405 // Various order invariants. Weaker than stores_are_sane because
5406 // a large constant tile can be filled in by smaller non-constant stores.
5407 assert(st_off >= last_init_off, "inits do not reverse");
5408 last_init_off = st_off;
5409 const Type* val = nullptr;
5410 if (st_size >= BytesPerInt &&
5411 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
5412 (int)val->basic_type() < (int)T_OBJECT) {
5413 assert(st_off >= last_tile_end, "tiles do not overlap");
5414 assert(st_off >= last_init_end, "tiles do not overwrite inits");
5415 last_tile_end = MAX2(last_tile_end, next_init_off);
5416 } else {
5417 intptr_t st_tile_end = align_up(next_init_off, BytesPerLong);
5418 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
5419 assert(st_off >= last_init_end, "inits do not overlap");
5420 last_init_end = next_init_off; // it's a non-tile
5421 }
5422 #endif //ASSERT
5423 }
5424
5425 remove_extra_zeroes(); // clear out all the zmems left over
5426 add_req(inits);
5427
5428 if (!(UseTLAB && ZeroTLAB)) {
5429 // If anything remains to be zeroed, zero it all now.
5430 zeroes_done = align_down(zeroes_done, BytesPerInt);
5431 // if it is the last unused 4 bytes of an instance, forget about it
5432 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
5433 if (zeroes_done + BytesPerLong >= size_limit) {
5434 AllocateNode* alloc = allocation();
5435 assert(alloc != nullptr, "must be present");
5436 if (alloc != nullptr && alloc->Opcode() == Op_Allocate) {
5437 Node* klass_node = alloc->in(AllocateNode::KlassNode);
5438 ciKlass* k = phase->type(klass_node)->is_instklassptr()->instance_klass();
5439 if (zeroes_done == k->layout_helper())
5440 zeroes_done = size_limit;
5441 }
5442 }
5443 if (zeroes_done < size_limit) {
5444 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
5445 zeroes_done, size_in_bytes, phase);
5446 }
5447 }
5448
5449 set_complete(phase);
5450 return rawmem;
5451 }
5452
5453
5454 #ifdef ASSERT
5455 bool InitializeNode::stores_are_sane(PhaseValues* phase) {
5456 if (is_complete())
5457 return true; // stores could be anything at this point
5458 assert(allocation() != nullptr, "must be present");
5459 intptr_t last_off = allocation()->minimum_header_size();
5460 for (uint i = InitializeNode::RawStores; i < req(); i++) {
5461 Node* st = in(i);
5462 intptr_t st_off = get_store_offset(st, phase);
5463 if (st_off < 0) continue; // ignore dead garbage
5464 if (last_off > st_off) {
5465 tty->print_cr("*** bad store offset at %d: %zd > %zd", i, last_off, st_off);
5466 this->dump(2);
5467 assert(false, "ascending store offsets");
5468 return false;
5469 }
5470 last_off = st_off + st->as_Store()->memory_size();
5471 }
5472 return true;
5473 }
5474 #endif //ASSERT
5475
5476
5477
5478
5479 //============================MergeMemNode=====================================
5480 //
5481 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
5482 // contributing store or call operations. Each contributor provides the memory
5483 // state for a particular "alias type" (see Compile::alias_type). For example,
5484 // if a MergeMem has an input X for alias category #6, then any memory reference
5485 // to alias category #6 may use X as its memory state input, as an exact equivalent
5486 // to using the MergeMem as a whole.
5487 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
5488 //
5489 // (Here, the <N> notation gives the index of the relevant adr_type.)
5490 //
5491 // In one special case (and more cases in the future), alias categories overlap.
5492 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
5493 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
5494 // it is exactly equivalent to that state W:
5495 // MergeMem(<Bot>: W) <==> W
5496 //
5497 // Usually, the merge has more than one input. In that case, where inputs
5498 // overlap (i.e., one is Bot), the narrower alias type determines the memory
5499 // state for that type, and the wider alias type (Bot) fills in everywhere else:
5500 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
5501 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
5502 //
5503 // A merge can take a "wide" memory state as one of its narrow inputs.
5504 // This simply means that the merge observes out only the relevant parts of
5505 // the wide input. That is, wide memory states arriving at narrow merge inputs
5506 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
5507 //
5508 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
5509 // and that memory slices "leak through":
5510 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
5511 //
5512 // But, in such a cascade, repeated memory slices can "block the leak":
5513 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
5514 //
5515 // In the last example, Y is not part of the combined memory state of the
5516 // outermost MergeMem. The system must, of course, prevent unschedulable
5517 // memory states from arising, so you can be sure that the state Y is somehow
5518 // a precursor to state Y'.
5519 //
5520 //
5521 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
5522 // of each MergeMemNode array are exactly the numerical alias indexes, including
5523 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
5524 // Compile::alias_type (and kin) produce and manage these indexes.
5525 //
5526 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
5527 // (Note that this provides quick access to the top node inside MergeMem methods,
5528 // without the need to reach out via TLS to Compile::current.)
5529 //
5530 // As a consequence of what was just described, a MergeMem that represents a full
5531 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
5532 // containing all alias categories.
5533 //
5534 // MergeMem nodes never (?) have control inputs, so in(0) is null.
5535 //
5536 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
5537 // a memory state for the alias type <N>, or else the top node, meaning that
5538 // there is no particular input for that alias type. Note that the length of
5539 // a MergeMem is variable, and may be extended at any time to accommodate new
5540 // memory states at larger alias indexes. When merges grow, they are of course
5541 // filled with "top" in the unused in() positions.
5542 //
5543 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
5544 // (Top was chosen because it works smoothly with passes like GCM.)
5545 //
5546 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
5547 // the type of random VM bits like TLS references.) Since it is always the
5548 // first non-Bot memory slice, some low-level loops use it to initialize an
5549 // index variable: for (i = AliasIdxRaw; i < req(); i++).
5550 //
5551 //
5552 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
5553 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
5554 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
5555 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
5556 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
5557 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
5558 //
5559 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
5560 // really that different from the other memory inputs. An abbreviation called
5561 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
5562 //
5563 //
5564 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
5565 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
5566 // that "emerges though" the base memory will be marked as excluding the alias types
5567 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
5568 //
5569 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
5570 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
5571 //
5572 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
5573 // (It is currently unimplemented.) As you can see, the resulting merge is
5574 // actually a disjoint union of memory states, rather than an overlay.
5575 //
5576
5577 //------------------------------MergeMemNode-----------------------------------
5578 Node* MergeMemNode::make_empty_memory() {
5579 Node* empty_memory = (Node*) Compile::current()->top();
5580 assert(empty_memory->is_top(), "correct sentinel identity");
5581 return empty_memory;
5582 }
5583
5584 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
5585 init_class_id(Class_MergeMem);
5586 // all inputs are nullified in Node::Node(int)
5587 // set_input(0, nullptr); // no control input
5588
5589 // Initialize the edges uniformly to top, for starters.
5590 Node* empty_mem = make_empty_memory();
5591 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
5592 init_req(i,empty_mem);
5593 }
5594 assert(empty_memory() == empty_mem, "");
5595
5596 if( new_base != nullptr && new_base->is_MergeMem() ) {
5597 MergeMemNode* mdef = new_base->as_MergeMem();
5598 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
5599 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
5600 mms.set_memory(mms.memory2());
5601 }
5602 assert(base_memory() == mdef->base_memory(), "");
5603 } else {
5604 set_base_memory(new_base);
5605 }
5606 }
5607
5608 // Make a new, untransformed MergeMem with the same base as 'mem'.
5609 // If mem is itself a MergeMem, populate the result with the same edges.
5610 MergeMemNode* MergeMemNode::make(Node* mem) {
5611 return new MergeMemNode(mem);
5612 }
5613
5614 //------------------------------cmp--------------------------------------------
5615 uint MergeMemNode::hash() const { return NO_HASH; }
5616 bool MergeMemNode::cmp( const Node &n ) const {
5617 return (&n == this); // Always fail except on self
5618 }
5619
5620 //------------------------------Identity---------------------------------------
5621 Node* MergeMemNode::Identity(PhaseGVN* phase) {
5622 // Identity if this merge point does not record any interesting memory
5623 // disambiguations.
5624 Node* base_mem = base_memory();
5625 Node* empty_mem = empty_memory();
5626 if (base_mem != empty_mem) { // Memory path is not dead?
5627 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5628 Node* mem = in(i);
5629 if (mem != empty_mem && mem != base_mem) {
5630 return this; // Many memory splits; no change
5631 }
5632 }
5633 }
5634 return base_mem; // No memory splits; ID on the one true input
5635 }
5636
5637 //------------------------------Ideal------------------------------------------
5638 // This method is invoked recursively on chains of MergeMem nodes
5639 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
5640 // Remove chain'd MergeMems
5641 //
5642 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
5643 // relative to the "in(Bot)". Since we are patching both at the same time,
5644 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
5645 // but rewrite each "in(i)" relative to the new "in(Bot)".
5646 Node *progress = nullptr;
5647
5648
5649 Node* old_base = base_memory();
5650 Node* empty_mem = empty_memory();
5651 if (old_base == empty_mem)
5652 return nullptr; // Dead memory path.
5653
5654 MergeMemNode* old_mbase;
5655 if (old_base != nullptr && old_base->is_MergeMem())
5656 old_mbase = old_base->as_MergeMem();
5657 else
5658 old_mbase = nullptr;
5659 Node* new_base = old_base;
5660
5661 // simplify stacked MergeMems in base memory
5662 if (old_mbase) new_base = old_mbase->base_memory();
5663
5664 // the base memory might contribute new slices beyond my req()
5665 if (old_mbase) grow_to_match(old_mbase);
5666
5667 // Note: We do not call verify_sparse on entry, because inputs
5668 // can normalize to the base_memory via subsume_node or similar
5669 // mechanisms. This method repairs that damage.
5670
5671 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
5672
5673 // Look at each slice.
5674 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5675 Node* old_in = in(i);
5676 // calculate the old memory value
5677 Node* old_mem = old_in;
5678 if (old_mem == empty_mem) old_mem = old_base;
5679 assert(old_mem == memory_at(i), "");
5680
5681 // maybe update (reslice) the old memory value
5682
5683 // simplify stacked MergeMems
5684 Node* new_mem = old_mem;
5685 MergeMemNode* old_mmem;
5686 if (old_mem != nullptr && old_mem->is_MergeMem())
5687 old_mmem = old_mem->as_MergeMem();
5688 else
5689 old_mmem = nullptr;
5690 if (old_mmem == this) {
5691 // This can happen if loops break up and safepoints disappear.
5692 // A merge of BotPtr (default) with a RawPtr memory derived from a
5693 // safepoint can be rewritten to a merge of the same BotPtr with
5694 // the BotPtr phi coming into the loop. If that phi disappears
5695 // also, we can end up with a self-loop of the mergemem.
5696 // In general, if loops degenerate and memory effects disappear,
5697 // a mergemem can be left looking at itself. This simply means
5698 // that the mergemem's default should be used, since there is
5699 // no longer any apparent effect on this slice.
5700 // Note: If a memory slice is a MergeMem cycle, it is unreachable
5701 // from start. Update the input to TOP.
5702 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
5703 }
5704 else if (old_mmem != nullptr) {
5705 new_mem = old_mmem->memory_at(i);
5706 }
5707 // else preceding memory was not a MergeMem
5708
5709 // maybe store down a new value
5710 Node* new_in = new_mem;
5711 if (new_in == new_base) new_in = empty_mem;
5712
5713 if (new_in != old_in) {
5714 // Warning: Do not combine this "if" with the previous "if"
5715 // A memory slice might have be be rewritten even if it is semantically
5716 // unchanged, if the base_memory value has changed.
5717 set_req_X(i, new_in, phase);
5718 progress = this; // Report progress
5719 }
5720 }
5721
5722 if (new_base != old_base) {
5723 set_req_X(Compile::AliasIdxBot, new_base, phase);
5724 // Don't use set_base_memory(new_base), because we need to update du.
5725 assert(base_memory() == new_base, "");
5726 progress = this;
5727 }
5728
5729 if( base_memory() == this ) {
5730 // a self cycle indicates this memory path is dead
5731 set_req(Compile::AliasIdxBot, empty_mem);
5732 }
5733
5734 // Resolve external cycles by calling Ideal on a MergeMem base_memory
5735 // Recursion must occur after the self cycle check above
5736 if( base_memory()->is_MergeMem() ) {
5737 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
5738 Node *m = phase->transform(new_mbase); // Rollup any cycles
5739 if( m != nullptr &&
5740 (m->is_top() ||
5741 (m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem)) ) {
5742 // propagate rollup of dead cycle to self
5743 set_req(Compile::AliasIdxBot, empty_mem);
5744 }
5745 }
5746
5747 if( base_memory() == empty_mem ) {
5748 progress = this;
5749 // Cut inputs during Parse phase only.
5750 // During Optimize phase a dead MergeMem node will be subsumed by Top.
5751 if( !can_reshape ) {
5752 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5753 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
5754 }
5755 }
5756 }
5757
5758 if( !progress && base_memory()->is_Phi() && can_reshape ) {
5759 // Check if PhiNode::Ideal's "Split phis through memory merges"
5760 // transform should be attempted. Look for this->phi->this cycle.
5761 uint merge_width = req();
5762 if (merge_width > Compile::AliasIdxRaw) {
5763 PhiNode* phi = base_memory()->as_Phi();
5764 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
5765 if (phi->in(i) == this) {
5766 phase->is_IterGVN()->_worklist.push(phi);
5767 break;
5768 }
5769 }
5770 }
5771 }
5772
5773 assert(progress || verify_sparse(), "please, no dups of base");
5774 return progress;
5775 }
5776
5777 //-------------------------set_base_memory-------------------------------------
5778 void MergeMemNode::set_base_memory(Node *new_base) {
5779 Node* empty_mem = empty_memory();
5780 set_req(Compile::AliasIdxBot, new_base);
5781 assert(memory_at(req()) == new_base, "must set default memory");
5782 // Clear out other occurrences of new_base:
5783 if (new_base != empty_mem) {
5784 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5785 if (in(i) == new_base) set_req(i, empty_mem);
5786 }
5787 }
5788 }
5789
5790 //------------------------------out_RegMask------------------------------------
5791 const RegMask &MergeMemNode::out_RegMask() const {
5792 return RegMask::Empty;
5793 }
5794
5795 //------------------------------dump_spec--------------------------------------
5796 #ifndef PRODUCT
5797 void MergeMemNode::dump_spec(outputStream *st) const {
5798 st->print(" {");
5799 Node* base_mem = base_memory();
5800 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
5801 Node* mem = (in(i) != nullptr) ? memory_at(i) : base_mem;
5802 if (mem == base_mem) { st->print(" -"); continue; }
5803 st->print( " N%d:", mem->_idx );
5804 Compile::current()->get_adr_type(i)->dump_on(st);
5805 }
5806 st->print(" }");
5807 }
5808 #endif // !PRODUCT
5809
5810
5811 #ifdef ASSERT
5812 static bool might_be_same(Node* a, Node* b) {
5813 if (a == b) return true;
5814 if (!(a->is_Phi() || b->is_Phi())) return false;
5815 // phis shift around during optimization
5816 return true; // pretty stupid...
5817 }
5818
5819 // verify a narrow slice (either incoming or outgoing)
5820 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
5821 if (!VerifyAliases) return; // don't bother to verify unless requested
5822 if (VMError::is_error_reported()) return; // muzzle asserts when debugging an error
5823 if (Node::in_dump()) return; // muzzle asserts when printing
5824 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
5825 assert(n != nullptr, "");
5826 // Elide intervening MergeMem's
5827 while (n->is_MergeMem()) {
5828 n = n->as_MergeMem()->memory_at(alias_idx);
5829 }
5830 Compile* C = Compile::current();
5831 const TypePtr* n_adr_type = n->adr_type();
5832 if (n == m->empty_memory()) {
5833 // Implicit copy of base_memory()
5834 } else if (n_adr_type != TypePtr::BOTTOM) {
5835 assert(n_adr_type != nullptr, "new memory must have a well-defined adr_type");
5836 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
5837 } else {
5838 // A few places like make_runtime_call "know" that VM calls are narrow,
5839 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
5840 bool expected_wide_mem = false;
5841 if (n == m->base_memory()) {
5842 expected_wide_mem = true;
5843 } else if (alias_idx == Compile::AliasIdxRaw ||
5844 n == m->memory_at(Compile::AliasIdxRaw)) {
5845 expected_wide_mem = true;
5846 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
5847 // memory can "leak through" calls on channels that
5848 // are write-once. Allow this also.
5849 expected_wide_mem = true;
5850 }
5851 assert(expected_wide_mem, "expected narrow slice replacement");
5852 }
5853 }
5854 #else // !ASSERT
5855 #define verify_memory_slice(m,i,n) (void)(0) // PRODUCT version is no-op
5856 #endif
5857
5858
5859 //-----------------------------memory_at---------------------------------------
5860 Node* MergeMemNode::memory_at(uint alias_idx) const {
5861 assert(alias_idx >= Compile::AliasIdxRaw ||
5862 (alias_idx == Compile::AliasIdxBot && !Compile::current()->do_aliasing()),
5863 "must avoid base_memory and AliasIdxTop");
5864
5865 // Otherwise, it is a narrow slice.
5866 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
5867 if (is_empty_memory(n)) {
5868 // the array is sparse; empty slots are the "top" node
5869 n = base_memory();
5870 assert(Node::in_dump()
5871 || n == nullptr || n->bottom_type() == Type::TOP
5872 || n->adr_type() == nullptr // address is TOP
5873 || n->adr_type() == TypePtr::BOTTOM
5874 || n->adr_type() == TypeRawPtr::BOTTOM
5875 || !Compile::current()->do_aliasing(),
5876 "must be a wide memory");
5877 // do_aliasing == false if we are organizing the memory states manually.
5878 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
5879 } else {
5880 // make sure the stored slice is sane
5881 #ifdef ASSERT
5882 if (VMError::is_error_reported() || Node::in_dump()) {
5883 } else if (might_be_same(n, base_memory())) {
5884 // Give it a pass: It is a mostly harmless repetition of the base.
5885 // This can arise normally from node subsumption during optimization.
5886 } else {
5887 verify_memory_slice(this, alias_idx, n);
5888 }
5889 #endif
5890 }
5891 return n;
5892 }
5893
5894 //---------------------------set_memory_at-------------------------------------
5895 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
5896 verify_memory_slice(this, alias_idx, n);
5897 Node* empty_mem = empty_memory();
5898 if (n == base_memory()) n = empty_mem; // collapse default
5899 uint need_req = alias_idx+1;
5900 if (req() < need_req) {
5901 if (n == empty_mem) return; // already the default, so do not grow me
5902 // grow the sparse array
5903 do {
5904 add_req(empty_mem);
5905 } while (req() < need_req);
5906 }
5907 set_req( alias_idx, n );
5908 }
5909
5910
5911
5912 //--------------------------iteration_setup------------------------------------
5913 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
5914 if (other != nullptr) {
5915 grow_to_match(other);
5916 // invariant: the finite support of mm2 is within mm->req()
5917 #ifdef ASSERT
5918 for (uint i = req(); i < other->req(); i++) {
5919 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
5920 }
5921 #endif
5922 }
5923 // Replace spurious copies of base_memory by top.
5924 Node* base_mem = base_memory();
5925 if (base_mem != nullptr && !base_mem->is_top()) {
5926 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
5927 if (in(i) == base_mem)
5928 set_req(i, empty_memory());
5929 }
5930 }
5931 }
5932
5933 //---------------------------grow_to_match-------------------------------------
5934 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
5935 Node* empty_mem = empty_memory();
5936 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
5937 // look for the finite support of the other memory
5938 for (uint i = other->req(); --i >= req(); ) {
5939 if (other->in(i) != empty_mem) {
5940 uint new_len = i+1;
5941 while (req() < new_len) add_req(empty_mem);
5942 break;
5943 }
5944 }
5945 }
5946
5947 //---------------------------verify_sparse-------------------------------------
5948 #ifndef PRODUCT
5949 bool MergeMemNode::verify_sparse() const {
5950 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
5951 Node* base_mem = base_memory();
5952 // The following can happen in degenerate cases, since empty==top.
5953 if (is_empty_memory(base_mem)) return true;
5954 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5955 assert(in(i) != nullptr, "sane slice");
5956 if (in(i) == base_mem) return false; // should have been the sentinel value!
5957 }
5958 return true;
5959 }
5960
5961 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
5962 Node* n;
5963 n = mm->in(idx);
5964 if (mem == n) return true; // might be empty_memory()
5965 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
5966 if (mem == n) return true;
5967 return false;
5968 }
5969 #endif // !PRODUCT