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