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 assert(!ld_offs_t->empty(), "dead reference should be checked already");
598 // Take into account vector or unsafe access size
599 jlong ld_size_in_bytes = (jlong)memory_size();
600 jlong offset_hi = ld_offs_t->_hi + ld_size_in_bytes - 1;
601 offset_hi = MIN2(offset_hi, (jlong)(TypeX::MAX->_hi)); // Take care for overflow in 32-bit VM
602 if (ac->modifies(ld_offs_t->_lo, (intptr_t)offset_hi, phase, can_see_stored_value)) {
603 return ac;
604 }
605 if (!can_see_stored_value) {
606 mem = ac->in(TypeFunc::Memory);
607 return ac;
608 }
609 }
610 }
611 }
612 }
613 return nullptr;
614 }
615
616 ArrayCopyNode* MemNode::find_array_copy_clone(PhaseValues* phase, Node* ld_alloc, Node* mem) const {
617 if (mem->is_Proj() && mem->in(0) != nullptr && (mem->in(0)->Opcode() == Op_MemBarStoreStore ||
618 mem->in(0)->Opcode() == Op_MemBarCPUOrder)) {
619 if (ld_alloc != nullptr) {
620 // Check if there is an array copy for a clone
621 Node* mb = mem->in(0);
622 ArrayCopyNode* ac = nullptr;
623 if (mb->in(0) != nullptr && mb->in(0)->is_Proj() &&
624 mb->in(0)->in(0) != nullptr && mb->in(0)->in(0)->is_ArrayCopy()) {
625 ac = mb->in(0)->in(0)->as_ArrayCopy();
626 } else {
627 // Step over GC barrier when ReduceInitialCardMarks is disabled
628 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
629 Node* control_proj_ac = bs->step_over_gc_barrier(mb->in(0));
630
631 if (control_proj_ac->is_Proj() && control_proj_ac->in(0)->is_ArrayCopy()) {
632 ac = control_proj_ac->in(0)->as_ArrayCopy();
633 }
634 }
635
636 if (ac != nullptr && ac->is_clonebasic()) {
637 AllocateNode* alloc = AllocateNode::Ideal_allocation(ac->in(ArrayCopyNode::Dest), phase);
638 if (alloc != nullptr && alloc == ld_alloc) {
639 return ac;
640 }
641 }
642 }
643 }
644 return nullptr;
645 }
646
647 // The logic for reordering loads and stores uses four steps:
648 // (a) Walk carefully past stores and initializations which we
649 // can prove are independent of this load.
650 // (b) Observe that the next memory state makes an exact match
651 // with self (load or store), and locate the relevant store.
652 // (c) Ensure that, if we were to wire self directly to the store,
653 // the optimizer would fold it up somehow.
654 // (d) Do the rewiring, and return, depending on some other part of
655 // the optimizer to fold up the load.
656 // This routine handles steps (a) and (b). Steps (c) and (d) are
657 // specific to loads and stores, so they are handled by the callers.
658 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.)
659 //
660 Node* MemNode::find_previous_store(PhaseValues* phase) {
661 Node* ctrl = in(MemNode::Control);
662 Node* adr = in(MemNode::Address);
663 intptr_t offset = 0;
664 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
665 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase);
666
667 if (offset == Type::OffsetBot)
668 return nullptr; // cannot unalias unless there are precise offsets
669
670 const bool adr_maybe_raw = check_if_adr_maybe_raw(adr);
671 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr();
672
673 intptr_t size_in_bytes = memory_size();
674
675 Node* mem = in(MemNode::Memory); // start searching here...
676
677 int cnt = 50; // Cycle limiter
678 for (;;) { // While we can dance past unrelated stores...
679 if (--cnt < 0) break; // Caught in cycle or a complicated dance?
680
681 Node* prev = mem;
682 if (mem->is_Store()) {
683 Node* st_adr = mem->in(MemNode::Address);
684 intptr_t st_offset = 0;
685 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
686 if (st_base == nullptr)
687 break; // inscrutable pointer
688
689 // For raw accesses it's not enough to prove that constant offsets don't intersect.
690 // We need the bases to be the equal in order for the offset check to make sense.
691 if ((adr_maybe_raw || check_if_adr_maybe_raw(st_adr)) && st_base != base) {
692 break;
693 }
694
695 if (st_offset != offset && st_offset != Type::OffsetBot) {
696 const int MAX_STORE = MAX2(BytesPerLong, (int)MaxVectorSize);
697 assert(mem->as_Store()->memory_size() <= MAX_STORE, "");
698 if (st_offset >= offset + size_in_bytes ||
699 st_offset <= offset - MAX_STORE ||
700 st_offset <= offset - mem->as_Store()->memory_size()) {
701 // Success: The offsets are provably independent.
702 // (You may ask, why not just test st_offset != offset and be done?
703 // The answer is that stores of different sizes can co-exist
704 // in the same sequence of RawMem effects. We sometimes initialize
705 // a whole 'tile' of array elements with a single jint or jlong.)
706 mem = mem->in(MemNode::Memory);
707 continue; // (a) advance through independent store memory
708 }
709 }
710 if (st_base != base &&
711 detect_ptr_independence(base, alloc,
712 st_base,
713 AllocateNode::Ideal_allocation(st_base, phase),
714 phase)) {
715 // Success: The bases are provably independent.
716 mem = mem->in(MemNode::Memory);
717 continue; // (a) advance through independent store memory
718 }
719
720 // (b) At this point, if the bases or offsets do not agree, we lose,
721 // since we have not managed to prove 'this' and 'mem' independent.
722 if (st_base == base && st_offset == offset) {
723 return mem; // let caller handle steps (c), (d)
724 }
725
726 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
727 InitializeNode* st_init = mem->in(0)->as_Initialize();
728 AllocateNode* st_alloc = st_init->allocation();
729 if (st_alloc == nullptr)
730 break; // something degenerated
731 bool known_identical = false;
732 bool known_independent = false;
733 if (alloc == st_alloc)
734 known_identical = true;
735 else if (alloc != nullptr)
736 known_independent = true;
737 else if (all_controls_dominate(this, st_alloc))
738 known_independent = true;
739
740 if (known_independent) {
741 // The bases are provably independent: Either they are
742 // manifestly distinct allocations, or else the control
743 // of this load dominates the store's allocation.
744 int alias_idx = phase->C->get_alias_index(adr_type());
745 if (alias_idx == Compile::AliasIdxRaw) {
746 mem = st_alloc->in(TypeFunc::Memory);
747 } else {
748 mem = st_init->memory(alias_idx);
749 }
750 continue; // (a) advance through independent store memory
751 }
752
753 // (b) at this point, if we are not looking at a store initializing
754 // the same allocation we are loading from, we lose.
755 if (known_identical) {
756 // From caller, can_see_stored_value will consult find_captured_store.
757 return mem; // let caller handle steps (c), (d)
758 }
759
760 } else if (find_previous_arraycopy(phase, alloc, mem, false) != nullptr) {
761 if (prev != mem) {
762 // Found an arraycopy but it doesn't affect that load
763 continue;
764 }
765 // Found an arraycopy that may affect that load
766 return mem;
767 } else if (addr_t != nullptr && addr_t->is_known_instance_field()) {
768 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
769 if (mem->is_Proj() && mem->in(0)->is_Call()) {
770 // ArrayCopyNodes processed here as well.
771 CallNode *call = mem->in(0)->as_Call();
772 if (!call->may_modify(addr_t, phase)) {
773 mem = call->in(TypeFunc::Memory);
774 continue; // (a) advance through independent call memory
775 }
776 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) {
777 ArrayCopyNode* ac = nullptr;
778 if (ArrayCopyNode::may_modify(addr_t, mem->in(0)->as_MemBar(), phase, ac)) {
779 break;
780 }
781 mem = mem->in(0)->in(TypeFunc::Memory);
782 continue; // (a) advance through independent MemBar memory
783 } else if (mem->is_ClearArray()) {
784 if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) {
785 // (the call updated 'mem' value)
786 continue; // (a) advance through independent allocation memory
787 } else {
788 // Can not bypass initialization of the instance
789 // we are looking for.
790 return mem;
791 }
792 } else if (mem->is_MergeMem()) {
793 int alias_idx = phase->C->get_alias_index(adr_type());
794 mem = mem->as_MergeMem()->memory_at(alias_idx);
795 continue; // (a) advance through independent MergeMem memory
796 }
797 }
798
799 // Unless there is an explicit 'continue', we must bail out here,
800 // because 'mem' is an inscrutable memory state (e.g., a call).
801 break;
802 }
803
804 return nullptr; // bail out
805 }
806
807 //----------------------calculate_adr_type-------------------------------------
808 // Helper function. Notices when the given type of address hits top or bottom.
809 // Also, asserts a cross-check of the type against the expected address type.
810 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
811 if (t == Type::TOP) return nullptr; // does not touch memory any more?
812 #ifdef ASSERT
813 if (!VerifyAliases || VMError::is_error_reported() || Node::in_dump()) cross_check = nullptr;
814 #endif
815 const TypePtr* tp = t->isa_ptr();
816 if (tp == nullptr) {
817 assert(cross_check == nullptr || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
818 return TypePtr::BOTTOM; // touches lots of memory
819 } else {
820 #ifdef ASSERT
821 // %%%% [phh] We don't check the alias index if cross_check is
822 // TypeRawPtr::BOTTOM. Needs to be investigated.
823 if (cross_check != nullptr &&
824 cross_check != TypePtr::BOTTOM &&
825 cross_check != TypeRawPtr::BOTTOM) {
826 // Recheck the alias index, to see if it has changed (due to a bug).
827 Compile* C = Compile::current();
828 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
829 "must stay in the original alias category");
830 // The type of the address must be contained in the adr_type,
831 // disregarding "null"-ness.
832 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
833 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
834 assert(cross_check->meet(tp_notnull) == cross_check->remove_speculative(),
835 "real address must not escape from expected memory type");
836 }
837 #endif
838 return tp;
839 }
840 }
841
842 //=============================================================================
843 // Should LoadNode::Ideal() attempt to remove control edges?
844 bool LoadNode::can_remove_control() const {
845 return !has_pinned_control_dependency();
846 }
847 uint LoadNode::size_of() const { return sizeof(*this); }
848 bool LoadNode::cmp(const Node &n) const {
849 LoadNode& load = (LoadNode &)n;
850 return !Type::cmp(_type, load._type) &&
851 _control_dependency == load._control_dependency &&
852 _mo == load._mo;
853 }
854 const Type *LoadNode::bottom_type() const { return _type; }
855 uint LoadNode::ideal_reg() const {
856 return _type->ideal_reg();
857 }
858
859 #ifndef PRODUCT
860 void LoadNode::dump_spec(outputStream *st) const {
861 MemNode::dump_spec(st);
862 if( !Verbose && !WizardMode ) {
863 // standard dump does this in Verbose and WizardMode
864 st->print(" #"); _type->dump_on(st);
865 }
866 if (!depends_only_on_test()) {
867 st->print(" (does not depend only on test, ");
868 if (control_dependency() == UnknownControl) {
869 st->print("unknown control");
870 } else if (control_dependency() == Pinned) {
871 st->print("pinned");
872 } else if (adr_type() == TypeRawPtr::BOTTOM) {
873 st->print("raw access");
874 } else {
875 st->print("unknown reason");
876 }
877 st->print(")");
878 }
879 }
880 #endif
881
882 #ifdef ASSERT
883 //----------------------------is_immutable_value-------------------------------
884 // Helper function to allow a raw load without control edge for some cases
885 bool LoadNode::is_immutable_value(Node* adr) {
886 if (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() &&
887 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal) {
888
889 jlong offset = adr->in(AddPNode::Offset)->find_intptr_t_con(-1);
890 int offsets[] = {
891 in_bytes(JavaThread::osthread_offset()),
892 in_bytes(JavaThread::threadObj_offset()),
893 in_bytes(JavaThread::vthread_offset()),
894 in_bytes(JavaThread::scopedValueCache_offset()),
895 };
896
897 for (size_t i = 0; i < sizeof offsets / sizeof offsets[0]; i++) {
898 if (offset == offsets[i]) {
899 return true;
900 }
901 }
902 }
903
904 return false;
905 }
906 #endif
907
908 //----------------------------LoadNode::make-----------------------------------
909 // Polymorphic factory method:
910 Node* LoadNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, BasicType bt, MemOrd mo,
911 ControlDependency control_dependency, bool require_atomic_access, bool unaligned, bool mismatched, bool unsafe, uint8_t barrier_data) {
912 Compile* C = gvn.C;
913
914 // sanity check the alias category against the created node type
915 assert(!(adr_type->isa_oopptr() &&
916 adr_type->offset() == oopDesc::klass_offset_in_bytes()),
917 "use LoadKlassNode instead");
918 assert(!(adr_type->isa_aryptr() &&
919 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
920 "use LoadRangeNode instead");
921 // Check control edge of raw loads
922 assert( ctl != nullptr || C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
923 // oop will be recorded in oop map if load crosses safepoint
924 rt->isa_oopptr() || is_immutable_value(adr),
925 "raw memory operations should have control edge");
926 LoadNode* load = nullptr;
927 switch (bt) {
928 case T_BOOLEAN: load = new LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
929 case T_BYTE: load = new LoadBNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
930 case T_INT: load = new LoadINode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
931 case T_CHAR: load = new LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
932 case T_SHORT: load = new LoadSNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
933 case T_LONG: load = new LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency, require_atomic_access); break;
934 case T_FLOAT: load = new LoadFNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); break;
935 case T_DOUBLE: load = new LoadDNode (ctl, mem, adr, adr_type, rt, mo, control_dependency, require_atomic_access); break;
936 case T_ADDRESS: load = new LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency); break;
937 case T_OBJECT:
938 #ifdef _LP64
939 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
940 load = new LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo, control_dependency);
941 } else
942 #endif
943 {
944 assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop");
945 load = new LoadPNode(ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency);
946 }
947 break;
948 default:
949 ShouldNotReachHere();
950 break;
951 }
952 assert(load != nullptr, "LoadNode should have been created");
953 if (unaligned) {
954 load->set_unaligned_access();
955 }
956 if (mismatched) {
957 load->set_mismatched_access();
958 }
959 if (unsafe) {
960 load->set_unsafe_access();
961 }
962 load->set_barrier_data(barrier_data);
963 if (load->Opcode() == Op_LoadN) {
964 Node* ld = gvn.transform(load);
965 return new DecodeNNode(ld, ld->bottom_type()->make_ptr());
966 }
967
968 return load;
969 }
970
971 //------------------------------hash-------------------------------------------
972 uint LoadNode::hash() const {
973 // unroll addition of interesting fields
974 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
975 }
976
977 static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) {
978 if ((atp != nullptr) && (atp->index() >= Compile::AliasIdxRaw)) {
979 bool non_volatile = (atp->field() != nullptr) && !atp->field()->is_volatile();
980 bool is_stable_ary = FoldStableValues &&
981 (tp != nullptr) && (tp->isa_aryptr() != nullptr) &&
982 tp->isa_aryptr()->is_stable();
983
984 return (eliminate_boxing && non_volatile) || is_stable_ary;
985 }
986
987 return false;
988 }
989
990 LoadNode* LoadNode::pin_array_access_node() const {
991 const TypePtr* adr_type = this->adr_type();
992 if (adr_type != nullptr && adr_type->isa_aryptr()) {
993 return clone_pinned();
994 }
995 return nullptr;
996 }
997
998 // Is the value loaded previously stored by an arraycopy? If so return
999 // a load node that reads from the source array so we may be able to
1000 // optimize out the ArrayCopy node later.
1001 Node* LoadNode::can_see_arraycopy_value(Node* st, PhaseGVN* phase) const {
1002 Node* ld_adr = in(MemNode::Address);
1003 intptr_t ld_off = 0;
1004 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
1005 Node* ac = find_previous_arraycopy(phase, ld_alloc, st, true);
1006 if (ac != nullptr) {
1007 assert(ac->is_ArrayCopy(), "what kind of node can this be?");
1008
1009 Node* mem = ac->in(TypeFunc::Memory);
1010 Node* ctl = ac->in(0);
1011 Node* src = ac->in(ArrayCopyNode::Src);
1012
1013 if (!ac->as_ArrayCopy()->is_clonebasic() && !phase->type(src)->isa_aryptr()) {
1014 return nullptr;
1015 }
1016
1017 // load depends on the tests that validate the arraycopy
1018 LoadNode* ld = clone_pinned();
1019 Node* addp = in(MemNode::Address)->clone();
1020 if (ac->as_ArrayCopy()->is_clonebasic()) {
1021 assert(ld_alloc != nullptr, "need an alloc");
1022 assert(addp->is_AddP(), "address must be addp");
1023 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1024 assert(bs->step_over_gc_barrier(addp->in(AddPNode::Base)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)), "strange pattern");
1025 assert(bs->step_over_gc_barrier(addp->in(AddPNode::Address)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)), "strange pattern");
1026 addp->set_req(AddPNode::Base, src);
1027 addp->set_req(AddPNode::Address, src);
1028 } else {
1029 assert(ac->as_ArrayCopy()->is_arraycopy_validated() ||
1030 ac->as_ArrayCopy()->is_copyof_validated() ||
1031 ac->as_ArrayCopy()->is_copyofrange_validated(), "only supported cases");
1032 assert(addp->in(AddPNode::Base) == addp->in(AddPNode::Address), "should be");
1033 addp->set_req(AddPNode::Base, src);
1034 addp->set_req(AddPNode::Address, src);
1035
1036 const TypeAryPtr* ary_t = phase->type(in(MemNode::Address))->isa_aryptr();
1037 BasicType ary_elem = ary_t->isa_aryptr()->elem()->array_element_basic_type();
1038 if (is_reference_type(ary_elem, true)) ary_elem = T_OBJECT;
1039
1040 uint header = arrayOopDesc::base_offset_in_bytes(ary_elem);
1041 uint shift = exact_log2(type2aelembytes(ary_elem));
1042
1043 Node* diff = phase->transform(new SubINode(ac->in(ArrayCopyNode::SrcPos), ac->in(ArrayCopyNode::DestPos)));
1044 #ifdef _LP64
1045 diff = phase->transform(new ConvI2LNode(diff));
1046 #endif
1047 diff = phase->transform(new LShiftXNode(diff, phase->intcon(shift)));
1048
1049 Node* offset = phase->transform(new AddXNode(addp->in(AddPNode::Offset), diff));
1050 addp->set_req(AddPNode::Offset, offset);
1051 }
1052 addp = phase->transform(addp);
1053 #ifdef ASSERT
1054 const TypePtr* adr_type = phase->type(addp)->is_ptr();
1055 ld->_adr_type = adr_type;
1056 #endif
1057 ld->set_req(MemNode::Address, addp);
1058 ld->set_req(0, ctl);
1059 ld->set_req(MemNode::Memory, mem);
1060 return ld;
1061 }
1062 return nullptr;
1063 }
1064
1065
1066 //---------------------------can_see_stored_value------------------------------
1067 // This routine exists to make sure this set of tests is done the same
1068 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
1069 // will change the graph shape in a way which makes memory alive twice at the
1070 // same time (uses the Oracle model of aliasing), then some
1071 // LoadXNode::Identity will fold things back to the equivalence-class model
1072 // of aliasing.
1073 Node* MemNode::can_see_stored_value(Node* st, PhaseValues* phase) const {
1074 Node* ld_adr = in(MemNode::Address);
1075 intptr_t ld_off = 0;
1076 Node* ld_base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ld_off);
1077 Node* ld_alloc = AllocateNode::Ideal_allocation(ld_base, phase);
1078 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
1079 Compile::AliasType* atp = (tp != nullptr) ? phase->C->alias_type(tp) : nullptr;
1080 // This is more general than load from boxing objects.
1081 if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) {
1082 uint alias_idx = atp->index();
1083 Node* result = nullptr;
1084 Node* current = st;
1085 // Skip through chains of MemBarNodes checking the MergeMems for
1086 // new states for the slice of this load. Stop once any other
1087 // kind of node is encountered. Loads from final memory can skip
1088 // through any kind of MemBar but normal loads shouldn't skip
1089 // through MemBarAcquire since the could allow them to move out of
1090 // a synchronized region. It is not safe to step over MemBarCPUOrder,
1091 // because alias info above them may be inaccurate (e.g., due to
1092 // mixed/mismatched unsafe accesses).
1093 bool is_final_mem = !atp->is_rewritable();
1094 while (current->is_Proj()) {
1095 int opc = current->in(0)->Opcode();
1096 if ((is_final_mem && (opc == Op_MemBarAcquire ||
1097 opc == Op_MemBarAcquireLock ||
1098 opc == Op_LoadFence)) ||
1099 opc == Op_MemBarRelease ||
1100 opc == Op_StoreFence ||
1101 opc == Op_MemBarReleaseLock ||
1102 opc == Op_MemBarStoreStore ||
1103 opc == Op_StoreStoreFence) {
1104 Node* mem = current->in(0)->in(TypeFunc::Memory);
1105 if (mem->is_MergeMem()) {
1106 MergeMemNode* merge = mem->as_MergeMem();
1107 Node* new_st = merge->memory_at(alias_idx);
1108 if (new_st == merge->base_memory()) {
1109 // Keep searching
1110 current = new_st;
1111 continue;
1112 }
1113 // Save the new memory state for the slice and fall through
1114 // to exit.
1115 result = new_st;
1116 }
1117 }
1118 break;
1119 }
1120 if (result != nullptr) {
1121 st = result;
1122 }
1123 }
1124
1125 // Loop around twice in the case Load -> Initialize -> Store.
1126 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
1127 for (int trip = 0; trip <= 1; trip++) {
1128
1129 if (st->is_Store()) {
1130 Node* st_adr = st->in(MemNode::Address);
1131 if (st_adr != ld_adr) {
1132 // Try harder before giving up. Unify base pointers with casts (e.g., raw/non-raw pointers).
1133 intptr_t st_off = 0;
1134 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_off);
1135 if (ld_base == nullptr) return nullptr;
1136 if (st_base == nullptr) return nullptr;
1137 if (!ld_base->eqv_uncast(st_base, /*keep_deps=*/true)) return nullptr;
1138 if (ld_off != st_off) return nullptr;
1139 if (ld_off == Type::OffsetBot) return nullptr;
1140 // Same base, same offset.
1141 // Possible improvement for arrays: check index value instead of absolute offset.
1142
1143 // At this point we have proven something like this setup:
1144 // B = << base >>
1145 // L = LoadQ(AddP(Check/CastPP(B), #Off))
1146 // S = StoreQ(AddP( B , #Off), V)
1147 // (Actually, we haven't yet proven the Q's are the same.)
1148 // In other words, we are loading from a casted version of
1149 // the same pointer-and-offset that we stored to.
1150 // Casted version may carry a dependency and it is respected.
1151 // Thus, we are able to replace L by V.
1152 }
1153 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
1154 if (store_Opcode() != st->Opcode()) {
1155 return nullptr;
1156 }
1157 // LoadVector/StoreVector needs additional check to ensure the types match.
1158 if (st->is_StoreVector()) {
1159 const TypeVect* in_vt = st->as_StoreVector()->vect_type();
1160 const TypeVect* out_vt = as_LoadVector()->vect_type();
1161 if (in_vt != out_vt) {
1162 return nullptr;
1163 }
1164 }
1165 return st->in(MemNode::ValueIn);
1166 }
1167
1168 // A load from a freshly-created object always returns zero.
1169 // (This can happen after LoadNode::Ideal resets the load's memory input
1170 // to find_captured_store, which returned InitializeNode::zero_memory.)
1171 if (st->is_Proj() && st->in(0)->is_Allocate() &&
1172 (st->in(0) == ld_alloc) &&
1173 (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) {
1174 // return a zero value for the load's basic type
1175 // (This is one of the few places where a generic PhaseTransform
1176 // can create new nodes. Think of it as lazily manifesting
1177 // virtually pre-existing constants.)
1178 if (memory_type() != T_VOID) {
1179 if (ReduceBulkZeroing || find_array_copy_clone(phase, ld_alloc, in(MemNode::Memory)) == nullptr) {
1180 // If ReduceBulkZeroing is disabled, we need to check if the allocation does not belong to an
1181 // ArrayCopyNode clone. If it does, then we cannot assume zero since the initialization is done
1182 // by the ArrayCopyNode.
1183 return phase->zerocon(memory_type());
1184 }
1185 } else {
1186 // TODO: materialize all-zero vector constant
1187 assert(!isa_Load() || as_Load()->type()->isa_vect(), "");
1188 }
1189 }
1190
1191 // A load from an initialization barrier can match a captured store.
1192 if (st->is_Proj() && st->in(0)->is_Initialize()) {
1193 InitializeNode* init = st->in(0)->as_Initialize();
1194 AllocateNode* alloc = init->allocation();
1195 if ((alloc != nullptr) && (alloc == ld_alloc)) {
1196 // examine a captured store value
1197 st = init->find_captured_store(ld_off, memory_size(), phase);
1198 if (st != nullptr) {
1199 continue; // take one more trip around
1200 }
1201 }
1202 }
1203
1204 // Load boxed value from result of valueOf() call is input parameter.
1205 if (this->is_Load() && ld_adr->is_AddP() &&
1206 (tp != nullptr) && tp->is_ptr_to_boxed_value()) {
1207 intptr_t ignore = 0;
1208 Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore);
1209 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1210 base = bs->step_over_gc_barrier(base);
1211 if (base != nullptr && base->is_Proj() &&
1212 base->as_Proj()->_con == TypeFunc::Parms &&
1213 base->in(0)->is_CallStaticJava() &&
1214 base->in(0)->as_CallStaticJava()->is_boxing_method()) {
1215 return base->in(0)->in(TypeFunc::Parms);
1216 }
1217 }
1218
1219 break;
1220 }
1221
1222 return nullptr;
1223 }
1224
1225 //----------------------is_instance_field_load_with_local_phi------------------
1226 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
1227 if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl &&
1228 in(Address)->is_AddP() ) {
1229 const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr();
1230 // Only instances and boxed values.
1231 if( t_oop != nullptr &&
1232 (t_oop->is_ptr_to_boxed_value() ||
1233 t_oop->is_known_instance_field()) &&
1234 t_oop->offset() != Type::OffsetBot &&
1235 t_oop->offset() != Type::OffsetTop) {
1236 return true;
1237 }
1238 }
1239 return false;
1240 }
1241
1242 //------------------------------Identity---------------------------------------
1243 // Loads are identity if previous store is to same address
1244 Node* LoadNode::Identity(PhaseGVN* phase) {
1245 // If the previous store-maker is the right kind of Store, and the store is
1246 // to the same address, then we are equal to the value stored.
1247 Node* mem = in(Memory);
1248 Node* value = can_see_stored_value(mem, phase);
1249 if( value ) {
1250 // byte, short & char stores truncate naturally.
1251 // A load has to load the truncated value which requires
1252 // some sort of masking operation and that requires an
1253 // Ideal call instead of an Identity call.
1254 if (memory_size() < BytesPerInt) {
1255 // If the input to the store does not fit with the load's result type,
1256 // it must be truncated via an Ideal call.
1257 if (!phase->type(value)->higher_equal(phase->type(this)))
1258 return this;
1259 }
1260 // (This works even when value is a Con, but LoadNode::Value
1261 // usually runs first, producing the singleton type of the Con.)
1262 if (!has_pinned_control_dependency() || value->is_Con()) {
1263 return value;
1264 } else {
1265 return this;
1266 }
1267 }
1268
1269 if (has_pinned_control_dependency()) {
1270 return this;
1271 }
1272 // Search for an existing data phi which was generated before for the same
1273 // instance's field to avoid infinite generation of phis in a loop.
1274 Node *region = mem->in(0);
1275 if (is_instance_field_load_with_local_phi(region)) {
1276 const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr();
1277 int this_index = phase->C->get_alias_index(addr_t);
1278 int this_offset = addr_t->offset();
1279 int this_iid = addr_t->instance_id();
1280 if (!addr_t->is_known_instance() &&
1281 addr_t->is_ptr_to_boxed_value()) {
1282 // Use _idx of address base (could be Phi node) for boxed values.
1283 intptr_t ignore = 0;
1284 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1285 if (base == nullptr) {
1286 return this;
1287 }
1288 this_iid = base->_idx;
1289 }
1290 const Type* this_type = bottom_type();
1291 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1292 Node* phi = region->fast_out(i);
1293 if (phi->is_Phi() && phi != mem &&
1294 phi->as_Phi()->is_same_inst_field(this_type, (int)mem->_idx, this_iid, this_index, this_offset)) {
1295 return phi;
1296 }
1297 }
1298 }
1299
1300 return this;
1301 }
1302
1303 // Construct an equivalent unsigned load.
1304 Node* LoadNode::convert_to_unsigned_load(PhaseGVN& gvn) {
1305 BasicType bt = T_ILLEGAL;
1306 const Type* rt = nullptr;
1307 switch (Opcode()) {
1308 case Op_LoadUB: return this;
1309 case Op_LoadUS: return this;
1310 case Op_LoadB: bt = T_BOOLEAN; rt = TypeInt::UBYTE; break;
1311 case Op_LoadS: bt = T_CHAR; rt = TypeInt::CHAR; break;
1312 default:
1313 assert(false, "no unsigned variant: %s", Name());
1314 return nullptr;
1315 }
1316 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1317 raw_adr_type(), rt, bt, _mo, _control_dependency,
1318 false /*require_atomic_access*/, is_unaligned_access(), is_mismatched_access());
1319 }
1320
1321 // Construct an equivalent signed load.
1322 Node* LoadNode::convert_to_signed_load(PhaseGVN& gvn) {
1323 BasicType bt = T_ILLEGAL;
1324 const Type* rt = nullptr;
1325 switch (Opcode()) {
1326 case Op_LoadUB: bt = T_BYTE; rt = TypeInt::BYTE; break;
1327 case Op_LoadUS: bt = T_SHORT; rt = TypeInt::SHORT; break;
1328 case Op_LoadB: // fall through
1329 case Op_LoadS: // fall through
1330 case Op_LoadI: // fall through
1331 case Op_LoadL: return this;
1332 default:
1333 assert(false, "no signed variant: %s", Name());
1334 return nullptr;
1335 }
1336 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1337 raw_adr_type(), rt, bt, _mo, _control_dependency,
1338 false /*require_atomic_access*/, is_unaligned_access(), is_mismatched_access());
1339 }
1340
1341 bool LoadNode::has_reinterpret_variant(const Type* rt) {
1342 BasicType bt = rt->basic_type();
1343 switch (Opcode()) {
1344 case Op_LoadI: return (bt == T_FLOAT);
1345 case Op_LoadL: return (bt == T_DOUBLE);
1346 case Op_LoadF: return (bt == T_INT);
1347 case Op_LoadD: return (bt == T_LONG);
1348
1349 default: return false;
1350 }
1351 }
1352
1353 Node* LoadNode::convert_to_reinterpret_load(PhaseGVN& gvn, const Type* rt) {
1354 BasicType bt = rt->basic_type();
1355 assert(has_reinterpret_variant(rt), "no reinterpret variant: %s %s", Name(), type2name(bt));
1356 bool is_mismatched = is_mismatched_access();
1357 const TypeRawPtr* raw_type = gvn.type(in(MemNode::Memory))->isa_rawptr();
1358 if (raw_type == nullptr) {
1359 is_mismatched = true; // conservatively match all non-raw accesses as mismatched
1360 }
1361 const int op = Opcode();
1362 bool require_atomic_access = (op == Op_LoadL && ((LoadLNode*)this)->require_atomic_access()) ||
1363 (op == Op_LoadD && ((LoadDNode*)this)->require_atomic_access());
1364 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1365 raw_adr_type(), rt, bt, _mo, _control_dependency,
1366 require_atomic_access, is_unaligned_access(), is_mismatched);
1367 }
1368
1369 bool StoreNode::has_reinterpret_variant(const Type* vt) {
1370 BasicType bt = vt->basic_type();
1371 switch (Opcode()) {
1372 case Op_StoreI: return (bt == T_FLOAT);
1373 case Op_StoreL: return (bt == T_DOUBLE);
1374 case Op_StoreF: return (bt == T_INT);
1375 case Op_StoreD: return (bt == T_LONG);
1376
1377 default: return false;
1378 }
1379 }
1380
1381 Node* StoreNode::convert_to_reinterpret_store(PhaseGVN& gvn, Node* val, const Type* vt) {
1382 BasicType bt = vt->basic_type();
1383 assert(has_reinterpret_variant(vt), "no reinterpret variant: %s %s", Name(), type2name(bt));
1384 const int op = Opcode();
1385 bool require_atomic_access = (op == Op_StoreL && ((StoreLNode*)this)->require_atomic_access()) ||
1386 (op == Op_StoreD && ((StoreDNode*)this)->require_atomic_access());
1387 StoreNode* st = StoreNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1388 raw_adr_type(), val, bt, _mo, require_atomic_access);
1389
1390 bool is_mismatched = is_mismatched_access();
1391 const TypeRawPtr* raw_type = gvn.type(in(MemNode::Memory))->isa_rawptr();
1392 if (raw_type == nullptr) {
1393 is_mismatched = true; // conservatively match all non-raw accesses as mismatched
1394 }
1395 if (is_mismatched) {
1396 st->set_mismatched_access();
1397 }
1398 return st;
1399 }
1400
1401 // We're loading from an object which has autobox behaviour.
1402 // If this object is result of a valueOf call we'll have a phi
1403 // merging a newly allocated object and a load from the cache.
1404 // We want to replace this load with the original incoming
1405 // argument to the valueOf call.
1406 Node* LoadNode::eliminate_autobox(PhaseIterGVN* igvn) {
1407 assert(igvn->C->eliminate_boxing(), "sanity");
1408 intptr_t ignore = 0;
1409 Node* base = AddPNode::Ideal_base_and_offset(in(Address), igvn, ignore);
1410 if ((base == nullptr) || base->is_Phi()) {
1411 // Push the loads from the phi that comes from valueOf up
1412 // through it to allow elimination of the loads and the recovery
1413 // of the original value. It is done in split_through_phi().
1414 return nullptr;
1415 } else if (base->is_Load() ||
1416 (base->is_DecodeN() && base->in(1)->is_Load())) {
1417 // Eliminate the load of boxed value for integer types from the cache
1418 // array by deriving the value from the index into the array.
1419 // Capture the offset of the load and then reverse the computation.
1420
1421 // Get LoadN node which loads a boxing object from 'cache' array.
1422 if (base->is_DecodeN()) {
1423 base = base->in(1);
1424 }
1425 if (!base->in(Address)->is_AddP()) {
1426 return nullptr; // Complex address
1427 }
1428 AddPNode* address = base->in(Address)->as_AddP();
1429 Node* cache_base = address->in(AddPNode::Base);
1430 if ((cache_base != nullptr) && cache_base->is_DecodeN()) {
1431 // Get ConP node which is static 'cache' field.
1432 cache_base = cache_base->in(1);
1433 }
1434 if ((cache_base != nullptr) && cache_base->is_Con()) {
1435 const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr();
1436 if ((base_type != nullptr) && base_type->is_autobox_cache()) {
1437 Node* elements[4];
1438 int shift = exact_log2(type2aelembytes(T_OBJECT));
1439 int count = address->unpack_offsets(elements, ARRAY_SIZE(elements));
1440 if (count > 0 && elements[0]->is_Con() &&
1441 (count == 1 ||
1442 (count == 2 && elements[1]->Opcode() == Op_LShiftX &&
1443 elements[1]->in(2) == igvn->intcon(shift)))) {
1444 ciObjArray* array = base_type->const_oop()->as_obj_array();
1445 // Fetch the box object cache[0] at the base of the array and get its value
1446 ciInstance* box = array->obj_at(0)->as_instance();
1447 ciInstanceKlass* ik = box->klass()->as_instance_klass();
1448 assert(ik->is_box_klass(), "sanity");
1449 assert(ik->nof_nonstatic_fields() == 1, "change following code");
1450 if (ik->nof_nonstatic_fields() == 1) {
1451 // This should be true nonstatic_field_at requires calling
1452 // nof_nonstatic_fields so check it anyway
1453 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1454 BasicType bt = c.basic_type();
1455 // Only integer types have boxing cache.
1456 assert(bt == T_BOOLEAN || bt == T_CHAR ||
1457 bt == T_BYTE || bt == T_SHORT ||
1458 bt == T_INT || bt == T_LONG, "wrong type = %s", type2name(bt));
1459 jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int();
1460 if (cache_low != (int)cache_low) {
1461 return nullptr; // should not happen since cache is array indexed by value
1462 }
1463 jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift);
1464 if (offset != (int)offset) {
1465 return nullptr; // should not happen since cache is array indexed by value
1466 }
1467 // Add up all the offsets making of the address of the load
1468 Node* result = elements[0];
1469 for (int i = 1; i < count; i++) {
1470 result = igvn->transform(new AddXNode(result, elements[i]));
1471 }
1472 // Remove the constant offset from the address and then
1473 result = igvn->transform(new AddXNode(result, igvn->MakeConX(-(int)offset)));
1474 // remove the scaling of the offset to recover the original index.
1475 if (result->Opcode() == Op_LShiftX && result->in(2) == igvn->intcon(shift)) {
1476 // Peel the shift off directly but wrap it in a dummy node
1477 // since Ideal can't return existing nodes
1478 igvn->_worklist.push(result); // remove dead node later
1479 result = new RShiftXNode(result->in(1), igvn->intcon(0));
1480 } else if (result->is_Add() && result->in(2)->is_Con() &&
1481 result->in(1)->Opcode() == Op_LShiftX &&
1482 result->in(1)->in(2) == igvn->intcon(shift)) {
1483 // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z)
1484 // but for boxing cache access we know that X<<Z will not overflow
1485 // (there is range check) so we do this optimizatrion by hand here.
1486 igvn->_worklist.push(result); // remove dead node later
1487 Node* add_con = new RShiftXNode(result->in(2), igvn->intcon(shift));
1488 result = new AddXNode(result->in(1)->in(1), igvn->transform(add_con));
1489 } else {
1490 result = new RShiftXNode(result, igvn->intcon(shift));
1491 }
1492 #ifdef _LP64
1493 if (bt != T_LONG) {
1494 result = new ConvL2INode(igvn->transform(result));
1495 }
1496 #else
1497 if (bt == T_LONG) {
1498 result = new ConvI2LNode(igvn->transform(result));
1499 }
1500 #endif
1501 // Boxing/unboxing can be done from signed & unsigned loads (e.g. LoadUB -> ... -> LoadB pair).
1502 // Need to preserve unboxing load type if it is unsigned.
1503 switch(this->Opcode()) {
1504 case Op_LoadUB:
1505 result = new AndINode(igvn->transform(result), igvn->intcon(0xFF));
1506 break;
1507 case Op_LoadUS:
1508 result = new AndINode(igvn->transform(result), igvn->intcon(0xFFFF));
1509 break;
1510 }
1511 return result;
1512 }
1513 }
1514 }
1515 }
1516 }
1517 return nullptr;
1518 }
1519
1520 static bool stable_phi(PhiNode* phi, PhaseGVN *phase) {
1521 Node* region = phi->in(0);
1522 if (region == nullptr) {
1523 return false; // Wait stable graph
1524 }
1525 uint cnt = phi->req();
1526 for (uint i = 1; i < cnt; i++) {
1527 Node* rc = region->in(i);
1528 if (rc == nullptr || phase->type(rc) == Type::TOP)
1529 return false; // Wait stable graph
1530 Node* in = phi->in(i);
1531 if (in == nullptr || phase->type(in) == Type::TOP)
1532 return false; // Wait stable graph
1533 }
1534 return true;
1535 }
1536 //------------------------------split_through_phi------------------------------
1537 // Split instance or boxed field load through Phi.
1538 Node* LoadNode::split_through_phi(PhaseGVN* phase) {
1539 if (req() > 3) {
1540 assert(is_LoadVector() && Opcode() != Op_LoadVector, "load has too many inputs");
1541 // LoadVector subclasses such as LoadVectorMasked have extra inputs that the logic below doesn't take into account
1542 return nullptr;
1543 }
1544 Node* mem = in(Memory);
1545 Node* address = in(Address);
1546 const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr();
1547
1548 assert((t_oop != nullptr) &&
1549 (t_oop->is_known_instance_field() ||
1550 t_oop->is_ptr_to_boxed_value()), "invalid conditions");
1551
1552 Compile* C = phase->C;
1553 intptr_t ignore = 0;
1554 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1555 bool base_is_phi = (base != nullptr) && base->is_Phi();
1556 bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() &&
1557 (base != nullptr) && (base == address->in(AddPNode::Base)) &&
1558 phase->type(base)->higher_equal(TypePtr::NOTNULL);
1559
1560 if (!((mem->is_Phi() || base_is_phi) &&
1561 (load_boxed_values || t_oop->is_known_instance_field()))) {
1562 return nullptr; // memory is not Phi
1563 }
1564
1565 if (mem->is_Phi()) {
1566 if (!stable_phi(mem->as_Phi(), phase)) {
1567 return nullptr; // Wait stable graph
1568 }
1569 uint cnt = mem->req();
1570 // Check for loop invariant memory.
1571 if (cnt == 3) {
1572 for (uint i = 1; i < cnt; i++) {
1573 Node* in = mem->in(i);
1574 Node* m = optimize_memory_chain(in, t_oop, this, phase);
1575 if (m == mem) {
1576 if (i == 1) {
1577 // if the first edge was a loop, check second edge too.
1578 // If both are replaceable - we are in an infinite loop
1579 Node *n = optimize_memory_chain(mem->in(2), t_oop, this, phase);
1580 if (n == mem) {
1581 break;
1582 }
1583 }
1584 set_req(Memory, mem->in(cnt - i));
1585 return this; // made change
1586 }
1587 }
1588 }
1589 }
1590 if (base_is_phi) {
1591 if (!stable_phi(base->as_Phi(), phase)) {
1592 return nullptr; // Wait stable graph
1593 }
1594 uint cnt = base->req();
1595 // Check for loop invariant memory.
1596 if (cnt == 3) {
1597 for (uint i = 1; i < cnt; i++) {
1598 if (base->in(i) == base) {
1599 return nullptr; // Wait stable graph
1600 }
1601 }
1602 }
1603 }
1604
1605 // Split through Phi (see original code in loopopts.cpp).
1606 assert(C->have_alias_type(t_oop), "instance should have alias type");
1607
1608 // Do nothing here if Identity will find a value
1609 // (to avoid infinite chain of value phis generation).
1610 if (this != Identity(phase)) {
1611 return nullptr;
1612 }
1613
1614 // Select Region to split through.
1615 Node* region;
1616 if (!base_is_phi) {
1617 assert(mem->is_Phi(), "sanity");
1618 region = mem->in(0);
1619 // Skip if the region dominates some control edge of the address.
1620 if (!MemNode::all_controls_dominate(address, region))
1621 return nullptr;
1622 } else if (!mem->is_Phi()) {
1623 assert(base_is_phi, "sanity");
1624 region = base->in(0);
1625 // Skip if the region dominates some control edge of the memory.
1626 if (!MemNode::all_controls_dominate(mem, region))
1627 return nullptr;
1628 } else if (base->in(0) != mem->in(0)) {
1629 assert(base_is_phi && mem->is_Phi(), "sanity");
1630 if (MemNode::all_controls_dominate(mem, base->in(0))) {
1631 region = base->in(0);
1632 } else if (MemNode::all_controls_dominate(address, mem->in(0))) {
1633 region = mem->in(0);
1634 } else {
1635 return nullptr; // complex graph
1636 }
1637 } else {
1638 assert(base->in(0) == mem->in(0), "sanity");
1639 region = mem->in(0);
1640 }
1641
1642 const Type* this_type = this->bottom_type();
1643 int this_index = C->get_alias_index(t_oop);
1644 int this_offset = t_oop->offset();
1645 int this_iid = t_oop->instance_id();
1646 if (!t_oop->is_known_instance() && load_boxed_values) {
1647 // Use _idx of address base for boxed values.
1648 this_iid = base->_idx;
1649 }
1650 PhaseIterGVN* igvn = phase->is_IterGVN();
1651 Node* phi = new PhiNode(region, this_type, nullptr, mem->_idx, this_iid, this_index, this_offset);
1652 for (uint i = 1; i < region->req(); i++) {
1653 Node* x;
1654 Node* the_clone = nullptr;
1655 Node* in = region->in(i);
1656 if (region->is_CountedLoop() && region->as_Loop()->is_strip_mined() && i == LoopNode::EntryControl &&
1657 in != nullptr && in->is_OuterStripMinedLoop()) {
1658 // No node should go in the outer strip mined loop
1659 in = in->in(LoopNode::EntryControl);
1660 }
1661 if (in == nullptr || in == C->top()) {
1662 x = C->top(); // Dead path? Use a dead data op
1663 } else {
1664 x = this->clone(); // Else clone up the data op
1665 the_clone = x; // Remember for possible deletion.
1666 // Alter data node to use pre-phi inputs
1667 if (this->in(0) == region) {
1668 x->set_req(0, in);
1669 } else {
1670 x->set_req(0, nullptr);
1671 }
1672 if (mem->is_Phi() && (mem->in(0) == region)) {
1673 x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone.
1674 }
1675 if (address->is_Phi() && address->in(0) == region) {
1676 x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone
1677 }
1678 if (base_is_phi && (base->in(0) == region)) {
1679 Node* base_x = base->in(i); // Clone address for loads from boxed objects.
1680 Node* adr_x = phase->transform(new AddPNode(base_x,base_x,address->in(AddPNode::Offset)));
1681 x->set_req(Address, adr_x);
1682 }
1683 }
1684 // Check for a 'win' on some paths
1685 const Type *t = x->Value(igvn);
1686
1687 bool singleton = t->singleton();
1688
1689 // See comments in PhaseIdealLoop::split_thru_phi().
1690 if (singleton && t == Type::TOP) {
1691 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1692 }
1693
1694 if (singleton) {
1695 x = igvn->makecon(t);
1696 } else {
1697 // We now call Identity to try to simplify the cloned node.
1698 // Note that some Identity methods call phase->type(this).
1699 // Make sure that the type array is big enough for
1700 // our new node, even though we may throw the node away.
1701 // (This tweaking with igvn only works because x is a new node.)
1702 igvn->set_type(x, t);
1703 // If x is a TypeNode, capture any more-precise type permanently into Node
1704 // otherwise it will be not updated during igvn->transform since
1705 // igvn->type(x) is set to x->Value() already.
1706 x->raise_bottom_type(t);
1707 Node* y = x->Identity(igvn);
1708 if (y != x) {
1709 x = y;
1710 } else {
1711 y = igvn->hash_find_insert(x);
1712 if (y) {
1713 x = y;
1714 } else {
1715 // Else x is a new node we are keeping
1716 // We do not need register_new_node_with_optimizer
1717 // because set_type has already been called.
1718 igvn->_worklist.push(x);
1719 }
1720 }
1721 }
1722 if (x != the_clone && the_clone != nullptr) {
1723 igvn->remove_dead_node(the_clone);
1724 }
1725 phi->set_req(i, x);
1726 }
1727 // Record Phi
1728 igvn->register_new_node_with_optimizer(phi);
1729 return phi;
1730 }
1731
1732 AllocateNode* LoadNode::is_new_object_mark_load(PhaseGVN *phase) const {
1733 if (Opcode() == Op_LoadX) {
1734 Node* address = in(MemNode::Address);
1735 AllocateNode* alloc = AllocateNode::Ideal_allocation(address, phase);
1736 Node* mem = in(MemNode::Memory);
1737 if (alloc != nullptr && mem->is_Proj() &&
1738 mem->in(0) != nullptr &&
1739 mem->in(0) == alloc->initialization() &&
1740 alloc->initialization()->proj_out_or_null(0) != nullptr) {
1741 return alloc;
1742 }
1743 }
1744 return nullptr;
1745 }
1746
1747
1748 //------------------------------Ideal------------------------------------------
1749 // If the load is from Field memory and the pointer is non-null, it might be possible to
1750 // zero out the control input.
1751 // If the offset is constant and the base is an object allocation,
1752 // try to hook me up to the exact initializing store.
1753 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1754 if (has_pinned_control_dependency()) {
1755 return nullptr;
1756 }
1757 Node* p = MemNode::Ideal_common(phase, can_reshape);
1758 if (p) return (p == NodeSentinel) ? nullptr : p;
1759
1760 Node* ctrl = in(MemNode::Control);
1761 Node* address = in(MemNode::Address);
1762 bool progress = false;
1763
1764 bool addr_mark = ((phase->type(address)->isa_oopptr() || phase->type(address)->isa_narrowoop()) &&
1765 phase->type(address)->is_ptr()->offset() == oopDesc::mark_offset_in_bytes());
1766
1767 // Skip up past a SafePoint control. Cannot do this for Stores because
1768 // pointer stores & cardmarks must stay on the same side of a SafePoint.
1769 if( ctrl != nullptr && ctrl->Opcode() == Op_SafePoint &&
1770 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw &&
1771 !addr_mark &&
1772 (depends_only_on_test() || has_unknown_control_dependency())) {
1773 ctrl = ctrl->in(0);
1774 set_req(MemNode::Control,ctrl);
1775 progress = true;
1776 }
1777
1778 intptr_t ignore = 0;
1779 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1780 if (base != nullptr
1781 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
1782 // Check for useless control edge in some common special cases
1783 if (in(MemNode::Control) != nullptr
1784 && can_remove_control()
1785 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1786 && all_controls_dominate(base, phase->C->start())) {
1787 // A method-invariant, non-null address (constant or 'this' argument).
1788 set_req(MemNode::Control, nullptr);
1789 progress = true;
1790 }
1791 }
1792
1793 Node* mem = in(MemNode::Memory);
1794 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1795
1796 if (can_reshape && (addr_t != nullptr)) {
1797 // try to optimize our memory input
1798 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase);
1799 if (opt_mem != mem) {
1800 set_req_X(MemNode::Memory, opt_mem, phase);
1801 if (phase->type( opt_mem ) == Type::TOP) return nullptr;
1802 return this;
1803 }
1804 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1805 if ((t_oop != nullptr) &&
1806 (t_oop->is_known_instance_field() ||
1807 t_oop->is_ptr_to_boxed_value())) {
1808 PhaseIterGVN *igvn = phase->is_IterGVN();
1809 assert(igvn != nullptr, "must be PhaseIterGVN when can_reshape is true");
1810 if (igvn->_worklist.member(opt_mem)) {
1811 // Delay this transformation until memory Phi is processed.
1812 igvn->_worklist.push(this);
1813 return nullptr;
1814 }
1815 // Split instance field load through Phi.
1816 Node* result = split_through_phi(phase);
1817 if (result != nullptr) return result;
1818
1819 if (t_oop->is_ptr_to_boxed_value()) {
1820 Node* result = eliminate_autobox(igvn);
1821 if (result != nullptr) return result;
1822 }
1823 }
1824 }
1825
1826 // Is there a dominating load that loads the same value? Leave
1827 // anything that is not a load of a field/array element (like
1828 // barriers etc.) alone
1829 if (in(0) != nullptr && !adr_type()->isa_rawptr() && can_reshape) {
1830 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) {
1831 Node *use = mem->fast_out(i);
1832 if (use != this &&
1833 use->Opcode() == Opcode() &&
1834 use->in(0) != nullptr &&
1835 use->in(0) != in(0) &&
1836 use->in(Address) == in(Address)) {
1837 Node* ctl = in(0);
1838 for (int i = 0; i < 10 && ctl != nullptr; i++) {
1839 ctl = IfNode::up_one_dom(ctl);
1840 if (ctl == use->in(0)) {
1841 set_req(0, use->in(0));
1842 return this;
1843 }
1844 }
1845 }
1846 }
1847 }
1848
1849 // Check for prior store with a different base or offset; make Load
1850 // independent. Skip through any number of them. Bail out if the stores
1851 // are in an endless dead cycle and report no progress. This is a key
1852 // transform for Reflection. However, if after skipping through the Stores
1853 // we can't then fold up against a prior store do NOT do the transform as
1854 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
1855 // array memory alive twice: once for the hoisted Load and again after the
1856 // bypassed Store. This situation only works if EVERYBODY who does
1857 // anti-dependence work knows how to bypass. I.e. we need all
1858 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
1859 // the alias index stuff. So instead, peek through Stores and IFF we can
1860 // fold up, do so.
1861 Node* prev_mem = find_previous_store(phase);
1862 if (prev_mem != nullptr) {
1863 Node* value = can_see_arraycopy_value(prev_mem, phase);
1864 if (value != nullptr) {
1865 return value;
1866 }
1867 }
1868 // Steps (a), (b): Walk past independent stores to find an exact match.
1869 if (prev_mem != nullptr && prev_mem != in(MemNode::Memory)) {
1870 // (c) See if we can fold up on the spot, but don't fold up here.
1871 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
1872 // just return a prior value, which is done by Identity calls.
1873 if (can_see_stored_value(prev_mem, phase)) {
1874 // Make ready for step (d):
1875 set_req_X(MemNode::Memory, prev_mem, phase);
1876 return this;
1877 }
1878 }
1879
1880 return progress ? this : nullptr;
1881 }
1882
1883 // Helper to recognize certain Klass fields which are invariant across
1884 // some group of array types (e.g., int[] or all T[] where T < Object).
1885 const Type*
1886 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1887 ciKlass* klass) const {
1888 if (UseCompactObjectHeaders) {
1889 if (tkls->offset() == in_bytes(Klass::prototype_header_offset())) {
1890 // The field is Klass::_prototype_header. Return its (constant) value.
1891 assert(this->Opcode() == Op_LoadX, "must load a proper type from _prototype_header");
1892 return TypeX::make(klass->prototype_header());
1893 }
1894 }
1895 if (tkls->offset() == in_bytes(Klass::modifier_flags_offset())) {
1896 // The field is Klass::_modifier_flags. Return its (constant) value.
1897 // (Folds up the 2nd indirection in aClassConstant.getModifiers().)
1898 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags");
1899 return TypeInt::make(klass->modifier_flags());
1900 }
1901 if (tkls->offset() == in_bytes(Klass::access_flags_offset())) {
1902 // The field is Klass::_access_flags. Return its (constant) value.
1903 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1904 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags");
1905 return TypeInt::make(klass->access_flags());
1906 }
1907 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) {
1908 // The field is Klass::_layout_helper. Return its constant value if known.
1909 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper");
1910 return TypeInt::make(klass->layout_helper());
1911 }
1912
1913 // No match.
1914 return nullptr;
1915 }
1916
1917 //------------------------------Value-----------------------------------------
1918 const Type* LoadNode::Value(PhaseGVN* phase) const {
1919 // Either input is TOP ==> the result is TOP
1920 Node* mem = in(MemNode::Memory);
1921 const Type *t1 = phase->type(mem);
1922 if (t1 == Type::TOP) return Type::TOP;
1923 Node* adr = in(MemNode::Address);
1924 const TypePtr* tp = phase->type(adr)->isa_ptr();
1925 if (tp == nullptr || tp->empty()) return Type::TOP;
1926 int off = tp->offset();
1927 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
1928 Compile* C = phase->C;
1929
1930 // Try to guess loaded type from pointer type
1931 if (tp->isa_aryptr()) {
1932 const TypeAryPtr* ary = tp->is_aryptr();
1933 const Type* t = ary->elem();
1934
1935 // Determine whether the reference is beyond the header or not, by comparing
1936 // the offset against the offset of the start of the array's data.
1937 // Different array types begin at slightly different offsets (12 vs. 16).
1938 // We choose T_BYTE as an example base type that is least restrictive
1939 // as to alignment, which will therefore produce the smallest
1940 // possible base offset.
1941 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
1942 const bool off_beyond_header = (off >= min_base_off);
1943
1944 // Try to constant-fold a stable array element.
1945 if (FoldStableValues && !is_mismatched_access() && ary->is_stable()) {
1946 // Make sure the reference is not into the header and the offset is constant
1947 ciObject* aobj = ary->const_oop();
1948 if (aobj != nullptr && off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) {
1949 int stable_dimension = (ary->stable_dimension() > 0 ? ary->stable_dimension() - 1 : 0);
1950 const Type* con_type = Type::make_constant_from_array_element(aobj->as_array(), off,
1951 stable_dimension,
1952 memory_type(), is_unsigned());
1953 if (con_type != nullptr) {
1954 return con_type;
1955 }
1956 }
1957 }
1958
1959 // Don't do this for integer types. There is only potential profit if
1960 // the element type t is lower than _type; that is, for int types, if _type is
1961 // more restrictive than t. This only happens here if one is short and the other
1962 // char (both 16 bits), and in those cases we've made an intentional decision
1963 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
1964 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
1965 //
1966 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
1967 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
1968 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
1969 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
1970 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
1971 // In fact, that could have been the original type of p1, and p1 could have
1972 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
1973 // expression (LShiftL quux 3) independently optimized to the constant 8.
1974 if ((t->isa_int() == nullptr) && (t->isa_long() == nullptr)
1975 && (_type->isa_vect() == nullptr)
1976 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
1977 // t might actually be lower than _type, if _type is a unique
1978 // concrete subclass of abstract class t.
1979 if (off_beyond_header || off == Type::OffsetBot) { // is the offset beyond the header?
1980 const Type* jt = t->join_speculative(_type);
1981 // In any case, do not allow the join, per se, to empty out the type.
1982 if (jt->empty() && !t->empty()) {
1983 // This can happen if a interface-typed array narrows to a class type.
1984 jt = _type;
1985 }
1986 #ifdef ASSERT
1987 if (phase->C->eliminate_boxing() && adr->is_AddP()) {
1988 // The pointers in the autobox arrays are always non-null
1989 Node* base = adr->in(AddPNode::Base);
1990 if ((base != nullptr) && base->is_DecodeN()) {
1991 // Get LoadN node which loads IntegerCache.cache field
1992 base = base->in(1);
1993 }
1994 if ((base != nullptr) && base->is_Con()) {
1995 const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr();
1996 if ((base_type != nullptr) && base_type->is_autobox_cache()) {
1997 // It could be narrow oop
1998 assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity");
1999 }
2000 }
2001 }
2002 #endif
2003 return jt;
2004 }
2005 }
2006 } else if (tp->base() == Type::InstPtr) {
2007 assert( off != Type::OffsetBot ||
2008 // arrays can be cast to Objects
2009 !tp->isa_instptr() ||
2010 tp->is_instptr()->instance_klass()->is_java_lang_Object() ||
2011 // unsafe field access may not have a constant offset
2012 C->has_unsafe_access(),
2013 "Field accesses must be precise" );
2014 // For oop loads, we expect the _type to be precise.
2015
2016 // Optimize loads from constant fields.
2017 const TypeInstPtr* tinst = tp->is_instptr();
2018 ciObject* const_oop = tinst->const_oop();
2019 if (!is_mismatched_access() && off != Type::OffsetBot && const_oop != nullptr && const_oop->is_instance()) {
2020 const Type* con_type = Type::make_constant_from_field(const_oop->as_instance(), off, is_unsigned(), memory_type());
2021 if (con_type != nullptr) {
2022 return con_type;
2023 }
2024 }
2025 } else if (tp->base() == Type::KlassPtr || tp->base() == Type::InstKlassPtr || tp->base() == Type::AryKlassPtr) {
2026 assert(off != Type::OffsetBot ||
2027 !tp->isa_instklassptr() ||
2028 // arrays can be cast to Objects
2029 tp->isa_instklassptr()->instance_klass()->is_java_lang_Object() ||
2030 // also allow array-loading from the primary supertype
2031 // array during subtype checks
2032 Opcode() == Op_LoadKlass,
2033 "Field accesses must be precise");
2034 // For klass/static loads, we expect the _type to be precise
2035 } else if (tp->base() == Type::RawPtr && adr->is_Load() && off == 0) {
2036 /* With mirrors being an indirect in the Klass*
2037 * the VM is now using two loads. LoadKlass(LoadP(LoadP(Klass, mirror_offset), zero_offset))
2038 * The LoadP from the Klass has a RawPtr type (see LibraryCallKit::load_mirror_from_klass).
2039 *
2040 * So check the type and klass of the node before the LoadP.
2041 */
2042 Node* adr2 = adr->in(MemNode::Address);
2043 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2044 if (tkls != nullptr && !StressReflectiveCode) {
2045 if (tkls->is_loaded() && tkls->klass_is_exact() && tkls->offset() == in_bytes(Klass::java_mirror_offset())) {
2046 ciKlass* klass = tkls->exact_klass();
2047 assert(adr->Opcode() == Op_LoadP, "must load an oop from _java_mirror");
2048 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
2049 return TypeInstPtr::make(klass->java_mirror());
2050 }
2051 }
2052 }
2053
2054 const TypeKlassPtr *tkls = tp->isa_klassptr();
2055 if (tkls != nullptr) {
2056 if (tkls->is_loaded() && tkls->klass_is_exact()) {
2057 ciKlass* klass = tkls->exact_klass();
2058 // We are loading a field from a Klass metaobject whose identity
2059 // is known at compile time (the type is "exact" or "precise").
2060 // Check for fields we know are maintained as constants by the VM.
2061 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) {
2062 // The field is Klass::_super_check_offset. Return its (constant) value.
2063 // (Folds up type checking code.)
2064 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
2065 return TypeInt::make(klass->super_check_offset());
2066 }
2067 if (UseCompactObjectHeaders) {
2068 if (tkls->offset() == in_bytes(Klass::prototype_header_offset())) {
2069 // The field is Klass::_prototype_header. Return its (constant) value.
2070 assert(this->Opcode() == Op_LoadX, "must load a proper type from _prototype_header");
2071 return TypeX::make(klass->prototype_header());
2072 }
2073 }
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 // The field is an element of Klass::_primary_supers. Return its (constant) value.
2079 // (Folds up type checking code.)
2080 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
2081 ciKlass *ss = klass->super_of_depth(depth);
2082 return ss ? TypeKlassPtr::make(ss, Type::trust_interfaces) : TypePtr::NULL_PTR;
2083 }
2084 const Type* aift = load_array_final_field(tkls, klass);
2085 if (aift != nullptr) return aift;
2086 }
2087
2088 // We can still check if we are loading from the primary_supers array at a
2089 // shallow enough depth. Even though the klass is not exact, entries less
2090 // than or equal to its super depth are correct.
2091 if (tkls->is_loaded()) {
2092 ciKlass* klass = nullptr;
2093 if (tkls->isa_instklassptr()) {
2094 klass = tkls->is_instklassptr()->instance_klass();
2095 } else {
2096 int dims;
2097 const Type* inner = tkls->is_aryklassptr()->base_element_type(dims);
2098 if (inner->isa_instklassptr()) {
2099 klass = inner->is_instklassptr()->instance_klass();
2100 klass = ciObjArrayKlass::make(klass, dims);
2101 }
2102 }
2103 if (klass != nullptr) {
2104 // Compute index into primary_supers array
2105 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
2106 // Check for overflowing; use unsigned compare to handle the negative case.
2107 if (depth < ciKlass::primary_super_limit() &&
2108 depth <= klass->super_depth()) { // allow self-depth checks to handle self-check case
2109 // The field is an element of Klass::_primary_supers. Return its (constant) value.
2110 // (Folds up type checking code.)
2111 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
2112 ciKlass *ss = klass->super_of_depth(depth);
2113 return ss ? TypeKlassPtr::make(ss, Type::trust_interfaces) : TypePtr::NULL_PTR;
2114 }
2115 }
2116 }
2117
2118 // If the type is enough to determine that the thing is not an array,
2119 // we can give the layout_helper a positive interval type.
2120 // This will help short-circuit some reflective code.
2121 if (tkls->offset() == in_bytes(Klass::layout_helper_offset()) &&
2122 tkls->isa_instklassptr() && // not directly typed as an array
2123 !tkls->is_instklassptr()->instance_klass()->is_java_lang_Object() // not the supertype of all T[] and specifically not Serializable & Cloneable
2124 ) {
2125 // Note: When interfaces are reliable, we can narrow the interface
2126 // test to (klass != Serializable && klass != Cloneable).
2127 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
2128 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
2129 // The key property of this type is that it folds up tests
2130 // for array-ness, since it proves that the layout_helper is positive.
2131 // Thus, a generic value like the basic object layout helper works fine.
2132 return TypeInt::make(min_size, max_jint, Type::WidenMin);
2133 }
2134 }
2135
2136 // If we are loading from a freshly-allocated object, produce a zero,
2137 // if the load is provably beyond the header of the object.
2138 // (Also allow a variable load from a fresh array to produce zero.)
2139 const TypeOopPtr *tinst = tp->isa_oopptr();
2140 bool is_instance = (tinst != nullptr) && tinst->is_known_instance_field();
2141 bool is_boxed_value = (tinst != nullptr) && tinst->is_ptr_to_boxed_value();
2142 if (ReduceFieldZeroing || is_instance || is_boxed_value) {
2143 Node* value = can_see_stored_value(mem,phase);
2144 if (value != nullptr && value->is_Con()) {
2145 assert(value->bottom_type()->higher_equal(_type),"sanity");
2146 return value->bottom_type();
2147 }
2148 }
2149
2150 bool is_vect = (_type->isa_vect() != nullptr);
2151 if (is_instance && !is_vect) {
2152 // If we have an instance type and our memory input is the
2153 // programs's initial memory state, there is no matching store,
2154 // so just return a zero of the appropriate type -
2155 // except if it is vectorized - then we have no zero constant.
2156 Node *mem = in(MemNode::Memory);
2157 if (mem->is_Parm() && mem->in(0)->is_Start()) {
2158 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
2159 return Type::get_zero_type(_type->basic_type());
2160 }
2161 }
2162
2163 Node* alloc = is_new_object_mark_load(phase);
2164 if (!UseCompactObjectHeaders && alloc != nullptr) {
2165 return TypeX::make(markWord::prototype().value());
2166 }
2167
2168 return _type;
2169 }
2170
2171 //------------------------------match_edge-------------------------------------
2172 // Do we Match on this edge index or not? Match only the address.
2173 uint LoadNode::match_edge(uint idx) const {
2174 return idx == MemNode::Address;
2175 }
2176
2177 //--------------------------LoadBNode::Ideal--------------------------------------
2178 //
2179 // If the previous store is to the same address as this load,
2180 // and the value stored was larger than a byte, replace this load
2181 // with the value stored truncated to a byte. If no truncation is
2182 // needed, the replacement is done in LoadNode::Identity().
2183 //
2184 Node* LoadBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2185 Node* mem = in(MemNode::Memory);
2186 Node* value = can_see_stored_value(mem,phase);
2187 if (value != nullptr) {
2188 Node* narrow = Compile::narrow_value(T_BYTE, value, _type, phase, false);
2189 if (narrow != value) {
2190 return narrow;
2191 }
2192 }
2193 // Identity call will handle the case where truncation is not needed.
2194 return LoadNode::Ideal(phase, can_reshape);
2195 }
2196
2197 const Type* LoadBNode::Value(PhaseGVN* phase) const {
2198 Node* mem = in(MemNode::Memory);
2199 Node* value = can_see_stored_value(mem,phase);
2200 if (value != nullptr && value->is_Con() &&
2201 !value->bottom_type()->higher_equal(_type)) {
2202 // If the input to the store does not fit with the load's result type,
2203 // it must be truncated. We can't delay until Ideal call since
2204 // a singleton Value is needed for split_thru_phi optimization.
2205 int con = value->get_int();
2206 return TypeInt::make((con << 24) >> 24);
2207 }
2208 return LoadNode::Value(phase);
2209 }
2210
2211 //--------------------------LoadUBNode::Ideal-------------------------------------
2212 //
2213 // If the previous store is to the same address as this load,
2214 // and the value stored was larger than a byte, replace this load
2215 // with the value stored truncated to a byte. If no truncation is
2216 // needed, the replacement is done in LoadNode::Identity().
2217 //
2218 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2219 Node* mem = in(MemNode::Memory);
2220 Node* value = can_see_stored_value(mem, phase);
2221 if (value != nullptr) {
2222 Node* narrow = Compile::narrow_value(T_BOOLEAN, value, _type, phase, false);
2223 if (narrow != value) {
2224 return narrow;
2225 }
2226 }
2227 // Identity call will handle the case where truncation is not needed.
2228 return LoadNode::Ideal(phase, can_reshape);
2229 }
2230
2231 const Type* LoadUBNode::Value(PhaseGVN* phase) const {
2232 Node* mem = in(MemNode::Memory);
2233 Node* value = can_see_stored_value(mem,phase);
2234 if (value != nullptr && value->is_Con() &&
2235 !value->bottom_type()->higher_equal(_type)) {
2236 // If the input to the store does not fit with the load's result type,
2237 // it must be truncated. We can't delay until Ideal call since
2238 // a singleton Value is needed for split_thru_phi optimization.
2239 int con = value->get_int();
2240 return TypeInt::make(con & 0xFF);
2241 }
2242 return LoadNode::Value(phase);
2243 }
2244
2245 //--------------------------LoadUSNode::Ideal-------------------------------------
2246 //
2247 // If the previous store is to the same address as this load,
2248 // and the value stored was larger than a char, replace this load
2249 // with the value stored truncated to a char. If no truncation is
2250 // needed, the replacement is done in LoadNode::Identity().
2251 //
2252 Node* LoadUSNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2253 Node* mem = in(MemNode::Memory);
2254 Node* value = can_see_stored_value(mem,phase);
2255 if (value != nullptr) {
2256 Node* narrow = Compile::narrow_value(T_CHAR, value, _type, phase, false);
2257 if (narrow != value) {
2258 return narrow;
2259 }
2260 }
2261 // Identity call will handle the case where truncation is not needed.
2262 return LoadNode::Ideal(phase, can_reshape);
2263 }
2264
2265 const Type* LoadUSNode::Value(PhaseGVN* phase) const {
2266 Node* mem = in(MemNode::Memory);
2267 Node* value = can_see_stored_value(mem,phase);
2268 if (value != nullptr && value->is_Con() &&
2269 !value->bottom_type()->higher_equal(_type)) {
2270 // If the input to the store does not fit with the load's result type,
2271 // it must be truncated. We can't delay until Ideal call since
2272 // a singleton Value is needed for split_thru_phi optimization.
2273 int con = value->get_int();
2274 return TypeInt::make(con & 0xFFFF);
2275 }
2276 return LoadNode::Value(phase);
2277 }
2278
2279 //--------------------------LoadSNode::Ideal--------------------------------------
2280 //
2281 // If the previous store is to the same address as this load,
2282 // and the value stored was larger than a short, replace this load
2283 // with the value stored truncated to a short. If no truncation is
2284 // needed, the replacement is done in LoadNode::Identity().
2285 //
2286 Node* LoadSNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2287 Node* mem = in(MemNode::Memory);
2288 Node* value = can_see_stored_value(mem,phase);
2289 if (value != nullptr) {
2290 Node* narrow = Compile::narrow_value(T_SHORT, value, _type, phase, false);
2291 if (narrow != value) {
2292 return narrow;
2293 }
2294 }
2295 // Identity call will handle the case where truncation is not needed.
2296 return LoadNode::Ideal(phase, can_reshape);
2297 }
2298
2299 const Type* LoadSNode::Value(PhaseGVN* phase) const {
2300 Node* mem = in(MemNode::Memory);
2301 Node* value = can_see_stored_value(mem,phase);
2302 if (value != nullptr && value->is_Con() &&
2303 !value->bottom_type()->higher_equal(_type)) {
2304 // If the input to the store does not fit with the load's result type,
2305 // it must be truncated. We can't delay until Ideal call since
2306 // a singleton Value is needed for split_thru_phi optimization.
2307 int con = value->get_int();
2308 return TypeInt::make((con << 16) >> 16);
2309 }
2310 return LoadNode::Value(phase);
2311 }
2312
2313 //=============================================================================
2314 //----------------------------LoadKlassNode::make------------------------------
2315 // Polymorphic factory method:
2316 Node* LoadKlassNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* at, const TypeKlassPtr* tk) {
2317 // sanity check the alias category against the created node type
2318 const TypePtr *adr_type = adr->bottom_type()->isa_ptr();
2319 assert(adr_type != nullptr, "expecting TypeKlassPtr");
2320 #ifdef _LP64
2321 if (adr_type->is_ptr_to_narrowklass()) {
2322 assert(UseCompressedClassPointers, "no compressed klasses");
2323 Node* load_klass = gvn.transform(new LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowklass(), MemNode::unordered));
2324 return new DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr());
2325 }
2326 #endif
2327 assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
2328 return new LoadKlassNode(ctl, mem, adr, at, tk, MemNode::unordered);
2329 }
2330
2331 //------------------------------Value------------------------------------------
2332 const Type* LoadKlassNode::Value(PhaseGVN* phase) const {
2333 return klass_value_common(phase);
2334 }
2335
2336 // In most cases, LoadKlassNode does not have the control input set. If the control
2337 // input is set, it must not be removed (by LoadNode::Ideal()).
2338 bool LoadKlassNode::can_remove_control() const {
2339 return false;
2340 }
2341
2342 const Type* LoadNode::klass_value_common(PhaseGVN* phase) const {
2343 // Either input is TOP ==> the result is TOP
2344 const Type *t1 = phase->type( in(MemNode::Memory) );
2345 if (t1 == Type::TOP) return Type::TOP;
2346 Node *adr = in(MemNode::Address);
2347 const Type *t2 = phase->type( adr );
2348 if (t2 == Type::TOP) return Type::TOP;
2349 const TypePtr *tp = t2->is_ptr();
2350 if (TypePtr::above_centerline(tp->ptr()) ||
2351 tp->ptr() == TypePtr::Null) return Type::TOP;
2352
2353 // Return a more precise klass, if possible
2354 const TypeInstPtr *tinst = tp->isa_instptr();
2355 if (tinst != nullptr) {
2356 ciInstanceKlass* ik = tinst->instance_klass();
2357 int offset = tinst->offset();
2358 if (ik == phase->C->env()->Class_klass()
2359 && (offset == java_lang_Class::klass_offset() ||
2360 offset == java_lang_Class::array_klass_offset())) {
2361 // We are loading a special hidden field from a Class mirror object,
2362 // the field which points to the VM's Klass metaobject.
2363 ciType* t = tinst->java_mirror_type();
2364 // java_mirror_type returns non-null for compile-time Class constants.
2365 if (t != nullptr) {
2366 // constant oop => constant klass
2367 if (offset == java_lang_Class::array_klass_offset()) {
2368 if (t->is_void()) {
2369 // We cannot create a void array. Since void is a primitive type return null
2370 // klass. Users of this result need to do a null check on the returned klass.
2371 return TypePtr::NULL_PTR;
2372 }
2373 return TypeKlassPtr::make(ciArrayKlass::make(t), Type::trust_interfaces);
2374 }
2375 if (!t->is_klass()) {
2376 // a primitive Class (e.g., int.class) has null for a klass field
2377 return TypePtr::NULL_PTR;
2378 }
2379 // (Folds up the 1st indirection in aClassConstant.getModifiers().)
2380 return TypeKlassPtr::make(t->as_klass(), Type::trust_interfaces);
2381 }
2382 // non-constant mirror, so we can't tell what's going on
2383 }
2384 if (!tinst->is_loaded())
2385 return _type; // Bail out if not loaded
2386 if (offset == oopDesc::klass_offset_in_bytes()) {
2387 return tinst->as_klass_type(true);
2388 }
2389 }
2390
2391 // Check for loading klass from an array
2392 const TypeAryPtr *tary = tp->isa_aryptr();
2393 if (tary != nullptr &&
2394 tary->offset() == oopDesc::klass_offset_in_bytes()) {
2395 return tary->as_klass_type(true);
2396 }
2397
2398 // Check for loading klass from an array klass
2399 const TypeKlassPtr *tkls = tp->isa_klassptr();
2400 if (tkls != nullptr && !StressReflectiveCode) {
2401 if (!tkls->is_loaded())
2402 return _type; // Bail out if not loaded
2403 if (tkls->isa_aryklassptr() && tkls->is_aryklassptr()->elem()->isa_klassptr() &&
2404 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) {
2405 // // Always returning precise element type is incorrect,
2406 // // e.g., element type could be object and array may contain strings
2407 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
2408
2409 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
2410 // according to the element type's subclassing.
2411 return tkls->is_aryklassptr()->elem()->isa_klassptr()->cast_to_exactness(tkls->klass_is_exact());
2412 }
2413 if (tkls->isa_instklassptr() != nullptr && tkls->klass_is_exact() &&
2414 tkls->offset() == in_bytes(Klass::super_offset())) {
2415 ciKlass* sup = tkls->is_instklassptr()->instance_klass()->super();
2416 // The field is Klass::_super. Return its (constant) value.
2417 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
2418 return sup ? TypeKlassPtr::make(sup, Type::trust_interfaces) : TypePtr::NULL_PTR;
2419 }
2420 }
2421
2422 // Bailout case
2423 return LoadNode::Value(phase);
2424 }
2425
2426 //------------------------------Identity---------------------------------------
2427 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
2428 // Also feed through the klass in Allocate(...klass...)._klass.
2429 Node* LoadKlassNode::Identity(PhaseGVN* phase) {
2430 return klass_identity_common(phase);
2431 }
2432
2433 Node* LoadNode::klass_identity_common(PhaseGVN* phase) {
2434 Node* x = LoadNode::Identity(phase);
2435 if (x != this) return x;
2436
2437 // Take apart the address into an oop and offset.
2438 // Return 'this' if we cannot.
2439 Node* adr = in(MemNode::Address);
2440 intptr_t offset = 0;
2441 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2442 if (base == nullptr) return this;
2443 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
2444 if (toop == nullptr) return this;
2445
2446 // Step over potential GC barrier for OopHandle resolve
2447 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
2448 if (bs->is_gc_barrier_node(base)) {
2449 base = bs->step_over_gc_barrier(base);
2450 }
2451
2452 // We can fetch the klass directly through an AllocateNode.
2453 // This works even if the klass is not constant (clone or newArray).
2454 if (offset == oopDesc::klass_offset_in_bytes()) {
2455 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
2456 if (allocated_klass != nullptr) {
2457 return allocated_klass;
2458 }
2459 }
2460
2461 // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*.
2462 // See inline_native_Class_query for occurrences of these patterns.
2463 // Java Example: x.getClass().isAssignableFrom(y)
2464 //
2465 // This improves reflective code, often making the Class
2466 // mirror go completely dead. (Current exception: Class
2467 // mirrors may appear in debug info, but we could clean them out by
2468 // introducing a new debug info operator for Klass.java_mirror).
2469
2470 if (toop->isa_instptr() && toop->is_instptr()->instance_klass() == phase->C->env()->Class_klass()
2471 && offset == java_lang_Class::klass_offset()) {
2472 if (base->is_Load()) {
2473 Node* base2 = base->in(MemNode::Address);
2474 if (base2->is_Load()) { /* direct load of a load which is the OopHandle */
2475 Node* adr2 = base2->in(MemNode::Address);
2476 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2477 if (tkls != nullptr && !tkls->empty()
2478 && (tkls->isa_instklassptr() || tkls->isa_aryklassptr())
2479 && adr2->is_AddP()
2480 ) {
2481 int mirror_field = in_bytes(Klass::java_mirror_offset());
2482 if (tkls->offset() == mirror_field) {
2483 return adr2->in(AddPNode::Base);
2484 }
2485 }
2486 }
2487 }
2488 }
2489
2490 return this;
2491 }
2492
2493 LoadNode* LoadNode::clone_pinned() const {
2494 LoadNode* ld = clone()->as_Load();
2495 ld->_control_dependency = UnknownControl;
2496 return ld;
2497 }
2498
2499
2500 //------------------------------Value------------------------------------------
2501 const Type* LoadNKlassNode::Value(PhaseGVN* phase) const {
2502 const Type *t = klass_value_common(phase);
2503 if (t == Type::TOP)
2504 return t;
2505
2506 return t->make_narrowklass();
2507 }
2508
2509 //------------------------------Identity---------------------------------------
2510 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
2511 // Also feed through the klass in Allocate(...klass...)._klass.
2512 Node* LoadNKlassNode::Identity(PhaseGVN* phase) {
2513 Node *x = klass_identity_common(phase);
2514
2515 const Type *t = phase->type( x );
2516 if( t == Type::TOP ) return x;
2517 if( t->isa_narrowklass()) return x;
2518 assert (!t->isa_narrowoop(), "no narrow oop here");
2519
2520 return phase->transform(new EncodePKlassNode(x, t->make_narrowklass()));
2521 }
2522
2523 //------------------------------Value-----------------------------------------
2524 const Type* LoadRangeNode::Value(PhaseGVN* phase) const {
2525 // Either input is TOP ==> the result is TOP
2526 const Type *t1 = phase->type( in(MemNode::Memory) );
2527 if( t1 == Type::TOP ) return Type::TOP;
2528 Node *adr = in(MemNode::Address);
2529 const Type *t2 = phase->type( adr );
2530 if( t2 == Type::TOP ) return Type::TOP;
2531 const TypePtr *tp = t2->is_ptr();
2532 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
2533 const TypeAryPtr *tap = tp->isa_aryptr();
2534 if( !tap ) return _type;
2535 return tap->size();
2536 }
2537
2538 //-------------------------------Ideal---------------------------------------
2539 // Feed through the length in AllocateArray(...length...)._length.
2540 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2541 Node* p = MemNode::Ideal_common(phase, can_reshape);
2542 if (p) return (p == NodeSentinel) ? nullptr : p;
2543
2544 // Take apart the address into an oop and offset.
2545 // Return 'this' if we cannot.
2546 Node* adr = in(MemNode::Address);
2547 intptr_t offset = 0;
2548 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2549 if (base == nullptr) return nullptr;
2550 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2551 if (tary == nullptr) return nullptr;
2552
2553 // We can fetch the length directly through an AllocateArrayNode.
2554 // This works even if the length is not constant (clone or newArray).
2555 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2556 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2557 if (alloc != nullptr) {
2558 Node* allocated_length = alloc->Ideal_length();
2559 Node* len = alloc->make_ideal_length(tary, phase);
2560 if (allocated_length != len) {
2561 // New CastII improves on this.
2562 return len;
2563 }
2564 }
2565 }
2566
2567 return nullptr;
2568 }
2569
2570 //------------------------------Identity---------------------------------------
2571 // Feed through the length in AllocateArray(...length...)._length.
2572 Node* LoadRangeNode::Identity(PhaseGVN* phase) {
2573 Node* x = LoadINode::Identity(phase);
2574 if (x != this) return x;
2575
2576 // Take apart the address into an oop and offset.
2577 // Return 'this' if we cannot.
2578 Node* adr = in(MemNode::Address);
2579 intptr_t offset = 0;
2580 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2581 if (base == nullptr) return this;
2582 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2583 if (tary == nullptr) return this;
2584
2585 // We can fetch the length directly through an AllocateArrayNode.
2586 // This works even if the length is not constant (clone or newArray).
2587 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2588 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2589 if (alloc != nullptr) {
2590 Node* allocated_length = alloc->Ideal_length();
2591 // Do not allow make_ideal_length to allocate a CastII node.
2592 Node* len = alloc->make_ideal_length(tary, phase, false);
2593 if (allocated_length == len) {
2594 // Return allocated_length only if it would not be improved by a CastII.
2595 return allocated_length;
2596 }
2597 }
2598 }
2599
2600 return this;
2601
2602 }
2603
2604 //=============================================================================
2605 //---------------------------StoreNode::make-----------------------------------
2606 // Polymorphic factory method:
2607 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) {
2608 assert((mo == unordered || mo == release), "unexpected");
2609 Compile* C = gvn.C;
2610 assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2611 ctl != nullptr, "raw memory operations should have control edge");
2612
2613 switch (bt) {
2614 case T_BOOLEAN: val = gvn.transform(new AndINode(val, gvn.intcon(0x1))); // Fall through to T_BYTE case
2615 case T_BYTE: return new StoreBNode(ctl, mem, adr, adr_type, val, mo);
2616 case T_INT: return new StoreINode(ctl, mem, adr, adr_type, val, mo);
2617 case T_CHAR:
2618 case T_SHORT: return new StoreCNode(ctl, mem, adr, adr_type, val, mo);
2619 case T_LONG: return new StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic_access);
2620 case T_FLOAT: return new StoreFNode(ctl, mem, adr, adr_type, val, mo);
2621 case T_DOUBLE: return new StoreDNode(ctl, mem, adr, adr_type, val, mo, require_atomic_access);
2622 case T_METADATA:
2623 case T_ADDRESS:
2624 case T_OBJECT:
2625 #ifdef _LP64
2626 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
2627 val = gvn.transform(new EncodePNode(val, val->bottom_type()->make_narrowoop()));
2628 return new StoreNNode(ctl, mem, adr, adr_type, val, mo);
2629 } else if (adr->bottom_type()->is_ptr_to_narrowklass() ||
2630 (UseCompressedClassPointers && val->bottom_type()->isa_klassptr() &&
2631 adr->bottom_type()->isa_rawptr())) {
2632 val = gvn.transform(new EncodePKlassNode(val, val->bottom_type()->make_narrowklass()));
2633 return new StoreNKlassNode(ctl, mem, adr, adr_type, val, mo);
2634 }
2635 #endif
2636 {
2637 return new StorePNode(ctl, mem, adr, adr_type, val, mo);
2638 }
2639 default:
2640 ShouldNotReachHere();
2641 return (StoreNode*)nullptr;
2642 }
2643 }
2644
2645 //--------------------------bottom_type----------------------------------------
2646 const Type *StoreNode::bottom_type() const {
2647 return Type::MEMORY;
2648 }
2649
2650 //------------------------------hash-------------------------------------------
2651 uint StoreNode::hash() const {
2652 // unroll addition of interesting fields
2653 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2654
2655 // Since they are not commoned, do not hash them:
2656 return NO_HASH;
2657 }
2658
2659 //------------------------------Ideal------------------------------------------
2660 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
2661 // When a store immediately follows a relevant allocation/initialization,
2662 // try to capture it into the initialization, or hoist it above.
2663 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2664 Node* p = MemNode::Ideal_common(phase, can_reshape);
2665 if (p) return (p == NodeSentinel) ? nullptr : p;
2666
2667 Node* mem = in(MemNode::Memory);
2668 Node* address = in(MemNode::Address);
2669 Node* value = in(MemNode::ValueIn);
2670 // Back-to-back stores to same address? Fold em up. Generally
2671 // unsafe if I have intervening uses... Also disallowed for StoreCM
2672 // since they must follow each StoreP operation. Redundant StoreCMs
2673 // are eliminated just before matching in final_graph_reshape.
2674 {
2675 Node* st = mem;
2676 // If Store 'st' has more than one use, we cannot fold 'st' away.
2677 // For example, 'st' might be the final state at a conditional
2678 // return. Or, 'st' might be used by some node which is live at
2679 // the same time 'st' is live, which might be unschedulable. So,
2680 // require exactly ONE user until such time as we clone 'mem' for
2681 // each of 'mem's uses (thus making the exactly-1-user-rule hold
2682 // true).
2683 while (st->is_Store() && st->outcnt() == 1 && st->Opcode() != Op_StoreCM) {
2684 // Looking at a dead closed cycle of memory?
2685 assert(st != st->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
2686 assert(Opcode() == st->Opcode() ||
2687 st->Opcode() == Op_StoreVector ||
2688 Opcode() == Op_StoreVector ||
2689 st->Opcode() == Op_StoreVectorScatter ||
2690 Opcode() == Op_StoreVectorScatter ||
2691 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw ||
2692 (Opcode() == Op_StoreL && st->Opcode() == Op_StoreI) || // expanded ClearArrayNode
2693 (Opcode() == Op_StoreI && st->Opcode() == Op_StoreL) || // initialization by arraycopy
2694 (is_mismatched_access() || st->as_Store()->is_mismatched_access()),
2695 "no mismatched stores, except on raw memory: %s %s", NodeClassNames[Opcode()], NodeClassNames[st->Opcode()]);
2696
2697 if (st->in(MemNode::Address)->eqv_uncast(address) &&
2698 st->as_Store()->memory_size() <= this->memory_size()) {
2699 Node* use = st->raw_out(0);
2700 if (phase->is_IterGVN()) {
2701 phase->is_IterGVN()->rehash_node_delayed(use);
2702 }
2703 // It's OK to do this in the parser, since DU info is always accurate,
2704 // and the parser always refers to nodes via SafePointNode maps.
2705 use->set_req_X(MemNode::Memory, st->in(MemNode::Memory), phase);
2706 return this;
2707 }
2708 st = st->in(MemNode::Memory);
2709 }
2710 }
2711
2712
2713 // Capture an unaliased, unconditional, simple store into an initializer.
2714 // Or, if it is independent of the allocation, hoist it above the allocation.
2715 if (ReduceFieldZeroing && /*can_reshape &&*/
2716 mem->is_Proj() && mem->in(0)->is_Initialize()) {
2717 InitializeNode* init = mem->in(0)->as_Initialize();
2718 intptr_t offset = init->can_capture_store(this, phase, can_reshape);
2719 if (offset > 0) {
2720 Node* moved = init->capture_store(this, offset, phase, can_reshape);
2721 // If the InitializeNode captured me, it made a raw copy of me,
2722 // and I need to disappear.
2723 if (moved != nullptr) {
2724 // %%% hack to ensure that Ideal returns a new node:
2725 mem = MergeMemNode::make(mem);
2726 return mem; // fold me away
2727 }
2728 }
2729 }
2730
2731 // Fold reinterpret cast into memory operation:
2732 // StoreX mem (MoveY2X v) => StoreY mem v
2733 if (value->is_Move()) {
2734 const Type* vt = value->in(1)->bottom_type();
2735 if (has_reinterpret_variant(vt)) {
2736 if (phase->C->post_loop_opts_phase()) {
2737 return convert_to_reinterpret_store(*phase, value->in(1), vt);
2738 } else {
2739 phase->C->record_for_post_loop_opts_igvn(this); // attempt the transformation once loop opts are over
2740 }
2741 }
2742 }
2743
2744 return nullptr; // No further progress
2745 }
2746
2747 //------------------------------Value-----------------------------------------
2748 const Type* StoreNode::Value(PhaseGVN* phase) const {
2749 // Either input is TOP ==> the result is TOP
2750 const Type *t1 = phase->type( in(MemNode::Memory) );
2751 if( t1 == Type::TOP ) return Type::TOP;
2752 const Type *t2 = phase->type( in(MemNode::Address) );
2753 if( t2 == Type::TOP ) return Type::TOP;
2754 const Type *t3 = phase->type( in(MemNode::ValueIn) );
2755 if( t3 == Type::TOP ) return Type::TOP;
2756 return Type::MEMORY;
2757 }
2758
2759 //------------------------------Identity---------------------------------------
2760 // Remove redundant stores:
2761 // Store(m, p, Load(m, p)) changes to m.
2762 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
2763 Node* StoreNode::Identity(PhaseGVN* phase) {
2764 Node* mem = in(MemNode::Memory);
2765 Node* adr = in(MemNode::Address);
2766 Node* val = in(MemNode::ValueIn);
2767
2768 Node* result = this;
2769
2770 // Load then Store? Then the Store is useless
2771 if (val->is_Load() &&
2772 val->in(MemNode::Address)->eqv_uncast(adr) &&
2773 val->in(MemNode::Memory )->eqv_uncast(mem) &&
2774 val->as_Load()->store_Opcode() == Opcode()) {
2775 // Ensure vector type is the same
2776 if (!is_StoreVector() || (mem->is_LoadVector() && as_StoreVector()->vect_type() == mem->as_LoadVector()->vect_type())) {
2777 result = mem;
2778 }
2779 }
2780
2781 // Two stores in a row of the same value?
2782 if (result == this &&
2783 mem->is_Store() &&
2784 mem->in(MemNode::Address)->eqv_uncast(adr) &&
2785 mem->in(MemNode::ValueIn)->eqv_uncast(val) &&
2786 mem->Opcode() == Opcode()) {
2787 if (!is_StoreVector()) {
2788 result = mem;
2789 } else {
2790 const StoreVectorNode* store_vector = as_StoreVector();
2791 const StoreVectorNode* mem_vector = mem->as_StoreVector();
2792 const Node* store_indices = store_vector->indices();
2793 const Node* mem_indices = mem_vector->indices();
2794 const Node* store_mask = store_vector->mask();
2795 const Node* mem_mask = mem_vector->mask();
2796 // Ensure types, indices, and masks match
2797 if (store_vector->vect_type() == mem_vector->vect_type() &&
2798 ((store_indices == nullptr) == (mem_indices == nullptr) &&
2799 (store_indices == nullptr || store_indices->eqv_uncast(mem_indices))) &&
2800 ((store_mask == nullptr) == (mem_mask == nullptr) &&
2801 (store_mask == nullptr || store_mask->eqv_uncast(mem_mask)))) {
2802 result = mem;
2803 }
2804 }
2805 }
2806
2807 // Store of zero anywhere into a freshly-allocated object?
2808 // Then the store is useless.
2809 // (It must already have been captured by the InitializeNode.)
2810 if (result == this &&
2811 ReduceFieldZeroing && phase->type(val)->is_zero_type()) {
2812 // a newly allocated object is already all-zeroes everywhere
2813 if (mem->is_Proj() && mem->in(0)->is_Allocate()) {
2814 result = mem;
2815 }
2816
2817 if (result == this) {
2818 // the store may also apply to zero-bits in an earlier object
2819 Node* prev_mem = find_previous_store(phase);
2820 // Steps (a), (b): Walk past independent stores to find an exact match.
2821 if (prev_mem != nullptr) {
2822 Node* prev_val = can_see_stored_value(prev_mem, phase);
2823 if (prev_val != nullptr && prev_val == val) {
2824 // prev_val and val might differ by a cast; it would be good
2825 // to keep the more informative of the two.
2826 result = mem;
2827 }
2828 }
2829 }
2830 }
2831
2832 PhaseIterGVN* igvn = phase->is_IterGVN();
2833 if (result != this && igvn != nullptr) {
2834 MemBarNode* trailing = trailing_membar();
2835 if (trailing != nullptr) {
2836 #ifdef ASSERT
2837 const TypeOopPtr* t_oop = phase->type(in(Address))->isa_oopptr();
2838 assert(t_oop == nullptr || t_oop->is_known_instance_field(), "only for non escaping objects");
2839 #endif
2840 trailing->remove(igvn);
2841 }
2842 }
2843
2844 return result;
2845 }
2846
2847 //------------------------------match_edge-------------------------------------
2848 // Do we Match on this edge index or not? Match only memory & value
2849 uint StoreNode::match_edge(uint idx) const {
2850 return idx == MemNode::Address || idx == MemNode::ValueIn;
2851 }
2852
2853 //------------------------------cmp--------------------------------------------
2854 // Do not common stores up together. They generally have to be split
2855 // back up anyways, so do not bother.
2856 bool StoreNode::cmp( const Node &n ) const {
2857 return (&n == this); // Always fail except on self
2858 }
2859
2860 //------------------------------Ideal_masked_input-----------------------------
2861 // Check for a useless mask before a partial-word store
2862 // (StoreB ... (AndI valIn conIa) )
2863 // If (conIa & mask == mask) this simplifies to
2864 // (StoreB ... (valIn) )
2865 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
2866 Node *val = in(MemNode::ValueIn);
2867 if( val->Opcode() == Op_AndI ) {
2868 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2869 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
2870 set_req_X(MemNode::ValueIn, val->in(1), phase);
2871 return this;
2872 }
2873 }
2874 return nullptr;
2875 }
2876
2877
2878 //------------------------------Ideal_sign_extended_input----------------------
2879 // Check for useless sign-extension before a partial-word store
2880 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) )
2881 // If (conIL == conIR && conIR <= num_bits) this simplifies to
2882 // (StoreB ... (valIn) )
2883 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) {
2884 Node *val = in(MemNode::ValueIn);
2885 if( val->Opcode() == Op_RShiftI ) {
2886 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2887 if( t && t->is_con() && (t->get_con() <= num_bits) ) {
2888 Node *shl = val->in(1);
2889 if( shl->Opcode() == Op_LShiftI ) {
2890 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int();
2891 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) {
2892 set_req_X(MemNode::ValueIn, shl->in(1), phase);
2893 return this;
2894 }
2895 }
2896 }
2897 }
2898 return nullptr;
2899 }
2900
2901 //------------------------------value_never_loaded-----------------------------------
2902 // Determine whether there are any possible loads of the value stored.
2903 // For simplicity, we actually check if there are any loads from the
2904 // address stored to, not just for loads of the value stored by this node.
2905 //
2906 bool StoreNode::value_never_loaded(PhaseValues* phase) const {
2907 Node *adr = in(Address);
2908 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
2909 if (adr_oop == nullptr)
2910 return false;
2911 if (!adr_oop->is_known_instance_field())
2912 return false; // if not a distinct instance, there may be aliases of the address
2913 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
2914 Node *use = adr->fast_out(i);
2915 if (use->is_Load() || use->is_LoadStore()) {
2916 return false;
2917 }
2918 }
2919 return true;
2920 }
2921
2922 MemBarNode* StoreNode::trailing_membar() const {
2923 if (is_release()) {
2924 MemBarNode* trailing_mb = nullptr;
2925 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
2926 Node* u = fast_out(i);
2927 if (u->is_MemBar()) {
2928 if (u->as_MemBar()->trailing_store()) {
2929 assert(u->Opcode() == Op_MemBarVolatile, "");
2930 assert(trailing_mb == nullptr, "only one");
2931 trailing_mb = u->as_MemBar();
2932 #ifdef ASSERT
2933 Node* leading = u->as_MemBar()->leading_membar();
2934 assert(leading->Opcode() == Op_MemBarRelease, "incorrect membar");
2935 assert(leading->as_MemBar()->leading_store(), "incorrect membar pair");
2936 assert(leading->as_MemBar()->trailing_membar() == u, "incorrect membar pair");
2937 #endif
2938 } else {
2939 assert(u->as_MemBar()->standalone(), "");
2940 }
2941 }
2942 }
2943 return trailing_mb;
2944 }
2945 return nullptr;
2946 }
2947
2948
2949 //=============================================================================
2950 //------------------------------Ideal------------------------------------------
2951 // If the store is from an AND mask that leaves the low bits untouched, then
2952 // we can skip the AND operation. If the store is from a sign-extension
2953 // (a left shift, then right shift) we can skip both.
2954 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
2955 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
2956 if( progress != nullptr ) return progress;
2957
2958 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
2959 if( progress != nullptr ) return progress;
2960
2961 // Finally check the default case
2962 return StoreNode::Ideal(phase, can_reshape);
2963 }
2964
2965 //=============================================================================
2966 //------------------------------Ideal------------------------------------------
2967 // If the store is from an AND mask that leaves the low bits untouched, then
2968 // we can skip the AND operation
2969 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
2970 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
2971 if( progress != nullptr ) return progress;
2972
2973 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
2974 if( progress != nullptr ) return progress;
2975
2976 // Finally check the default case
2977 return StoreNode::Ideal(phase, can_reshape);
2978 }
2979
2980 //=============================================================================
2981 //------------------------------Identity---------------------------------------
2982 Node* StoreCMNode::Identity(PhaseGVN* phase) {
2983 // No need to card mark when storing a null ptr
2984 Node* my_store = in(MemNode::OopStore);
2985 if (my_store->is_Store()) {
2986 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) );
2987 if( t1 == TypePtr::NULL_PTR ) {
2988 return in(MemNode::Memory);
2989 }
2990 }
2991 return this;
2992 }
2993
2994 //=============================================================================
2995 //------------------------------Ideal---------------------------------------
2996 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){
2997 Node* progress = StoreNode::Ideal(phase, can_reshape);
2998 if (progress != nullptr) return progress;
2999
3000 Node* my_store = in(MemNode::OopStore);
3001 if (my_store->is_MergeMem()) {
3002 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx());
3003 set_req_X(MemNode::OopStore, mem, phase);
3004 return this;
3005 }
3006
3007 return nullptr;
3008 }
3009
3010 //------------------------------Value-----------------------------------------
3011 const Type* StoreCMNode::Value(PhaseGVN* phase) const {
3012 // Either input is TOP ==> the result is TOP (checked in StoreNode::Value).
3013 // If extra input is TOP ==> the result is TOP
3014 const Type* t = phase->type(in(MemNode::OopStore));
3015 if (t == Type::TOP) {
3016 return Type::TOP;
3017 }
3018 return StoreNode::Value(phase);
3019 }
3020
3021
3022 //=============================================================================
3023 //----------------------------------SCMemProjNode------------------------------
3024 const Type* SCMemProjNode::Value(PhaseGVN* phase) const
3025 {
3026 if (in(0) == nullptr || phase->type(in(0)) == Type::TOP) {
3027 return Type::TOP;
3028 }
3029 return bottom_type();
3030 }
3031
3032 //=============================================================================
3033 //----------------------------------LoadStoreNode------------------------------
3034 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required )
3035 : Node(required),
3036 _type(rt),
3037 _adr_type(at),
3038 _barrier_data(0)
3039 {
3040 init_req(MemNode::Control, c );
3041 init_req(MemNode::Memory , mem);
3042 init_req(MemNode::Address, adr);
3043 init_req(MemNode::ValueIn, val);
3044 init_class_id(Class_LoadStore);
3045 }
3046
3047 //------------------------------Value-----------------------------------------
3048 const Type* LoadStoreNode::Value(PhaseGVN* phase) const {
3049 // Either input is TOP ==> the result is TOP
3050 if (!in(MemNode::Control) || phase->type(in(MemNode::Control)) == Type::TOP) {
3051 return Type::TOP;
3052 }
3053 const Type* t = phase->type(in(MemNode::Memory));
3054 if (t == Type::TOP) {
3055 return Type::TOP;
3056 }
3057 t = phase->type(in(MemNode::Address));
3058 if (t == Type::TOP) {
3059 return Type::TOP;
3060 }
3061 t = phase->type(in(MemNode::ValueIn));
3062 if (t == Type::TOP) {
3063 return Type::TOP;
3064 }
3065 return bottom_type();
3066 }
3067
3068 uint LoadStoreNode::ideal_reg() const {
3069 return _type->ideal_reg();
3070 }
3071
3072 bool LoadStoreNode::result_not_used() const {
3073 for( DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++ ) {
3074 Node *x = fast_out(i);
3075 if (x->Opcode() == Op_SCMemProj) continue;
3076 return false;
3077 }
3078 return true;
3079 }
3080
3081 MemBarNode* LoadStoreNode::trailing_membar() const {
3082 MemBarNode* trailing = nullptr;
3083 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
3084 Node* u = fast_out(i);
3085 if (u->is_MemBar()) {
3086 if (u->as_MemBar()->trailing_load_store()) {
3087 assert(u->Opcode() == Op_MemBarAcquire, "");
3088 assert(trailing == nullptr, "only one");
3089 trailing = u->as_MemBar();
3090 #ifdef ASSERT
3091 Node* leading = trailing->leading_membar();
3092 assert(support_IRIW_for_not_multiple_copy_atomic_cpu || leading->Opcode() == Op_MemBarRelease, "incorrect membar");
3093 assert(leading->as_MemBar()->leading_load_store(), "incorrect membar pair");
3094 assert(leading->as_MemBar()->trailing_membar() == trailing, "incorrect membar pair");
3095 #endif
3096 } else {
3097 assert(u->as_MemBar()->standalone(), "wrong barrier kind");
3098 }
3099 }
3100 }
3101
3102 return trailing;
3103 }
3104
3105 uint LoadStoreNode::size_of() const { return sizeof(*this); }
3106
3107 //=============================================================================
3108 //----------------------------------LoadStoreConditionalNode--------------------
3109 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, nullptr, TypeInt::BOOL, 5) {
3110 init_req(ExpectedIn, ex );
3111 }
3112
3113 const Type* LoadStoreConditionalNode::Value(PhaseGVN* phase) const {
3114 // Either input is TOP ==> the result is TOP
3115 const Type* t = phase->type(in(ExpectedIn));
3116 if (t == Type::TOP) {
3117 return Type::TOP;
3118 }
3119 return LoadStoreNode::Value(phase);
3120 }
3121
3122 //=============================================================================
3123 //-------------------------------adr_type--------------------------------------
3124 const TypePtr* ClearArrayNode::adr_type() const {
3125 Node *adr = in(3);
3126 if (adr == nullptr) return nullptr; // node is dead
3127 return MemNode::calculate_adr_type(adr->bottom_type());
3128 }
3129
3130 //------------------------------match_edge-------------------------------------
3131 // Do we Match on this edge index or not? Do not match memory
3132 uint ClearArrayNode::match_edge(uint idx) const {
3133 return idx > 1;
3134 }
3135
3136 //------------------------------Identity---------------------------------------
3137 // Clearing a zero length array does nothing
3138 Node* ClearArrayNode::Identity(PhaseGVN* phase) {
3139 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
3140 }
3141
3142 //------------------------------Idealize---------------------------------------
3143 // Clearing a short array is faster with stores
3144 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3145 // Already know this is a large node, do not try to ideal it
3146 if (_is_large) return nullptr;
3147
3148 const int unit = BytesPerLong;
3149 const TypeX* t = phase->type(in(2))->isa_intptr_t();
3150 if (!t) return nullptr;
3151 if (!t->is_con()) return nullptr;
3152 intptr_t raw_count = t->get_con();
3153 intptr_t size = raw_count;
3154 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
3155 // Clearing nothing uses the Identity call.
3156 // Negative clears are possible on dead ClearArrays
3157 // (see jck test stmt114.stmt11402.val).
3158 if (size <= 0 || size % unit != 0) return nullptr;
3159 intptr_t count = size / unit;
3160 // Length too long; communicate this to matchers and assemblers.
3161 // Assemblers are responsible to produce fast hardware clears for it.
3162 if (size > InitArrayShortSize) {
3163 return new ClearArrayNode(in(0), in(1), in(2), in(3), true);
3164 } else if (size > 2 && Matcher::match_rule_supported_vector(Op_ClearArray, 4, T_LONG)) {
3165 return nullptr;
3166 }
3167 if (!IdealizeClearArrayNode) return nullptr;
3168 Node *mem = in(1);
3169 if( phase->type(mem)==Type::TOP ) return nullptr;
3170 Node *adr = in(3);
3171 const Type* at = phase->type(adr);
3172 if( at==Type::TOP ) return nullptr;
3173 const TypePtr* atp = at->isa_ptr();
3174 // adjust atp to be the correct array element address type
3175 if (atp == nullptr) atp = TypePtr::BOTTOM;
3176 else atp = atp->add_offset(Type::OffsetBot);
3177 // Get base for derived pointer purposes
3178 if( adr->Opcode() != Op_AddP ) Unimplemented();
3179 Node *base = adr->in(1);
3180
3181 Node *zero = phase->makecon(TypeLong::ZERO);
3182 Node *off = phase->MakeConX(BytesPerLong);
3183 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
3184 count--;
3185 while( count-- ) {
3186 mem = phase->transform(mem);
3187 adr = phase->transform(new AddPNode(base,adr,off));
3188 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
3189 }
3190 return mem;
3191 }
3192
3193 //----------------------------step_through----------------------------------
3194 // Return allocation input memory edge if it is different instance
3195 // or itself if it is the one we are looking for.
3196 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseValues* phase) {
3197 Node* n = *np;
3198 assert(n->is_ClearArray(), "sanity");
3199 intptr_t offset;
3200 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
3201 // This method is called only before Allocate nodes are expanded
3202 // during macro nodes expansion. Before that ClearArray nodes are
3203 // only generated in PhaseMacroExpand::generate_arraycopy() (before
3204 // Allocate nodes are expanded) which follows allocations.
3205 assert(alloc != nullptr, "should have allocation");
3206 if (alloc->_idx == instance_id) {
3207 // Can not bypass initialization of the instance we are looking for.
3208 return false;
3209 }
3210 // Otherwise skip it.
3211 InitializeNode* init = alloc->initialization();
3212 if (init != nullptr)
3213 *np = init->in(TypeFunc::Memory);
3214 else
3215 *np = alloc->in(TypeFunc::Memory);
3216 return true;
3217 }
3218
3219 //----------------------------clear_memory-------------------------------------
3220 // Generate code to initialize object storage to zero.
3221 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
3222 intptr_t start_offset,
3223 Node* end_offset,
3224 PhaseGVN* phase) {
3225 intptr_t offset = start_offset;
3226
3227 int unit = BytesPerLong;
3228 if ((offset % unit) != 0) {
3229 Node* adr = new AddPNode(dest, dest, phase->MakeConX(offset));
3230 adr = phase->transform(adr);
3231 const TypePtr* atp = TypeRawPtr::BOTTOM;
3232 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
3233 mem = phase->transform(mem);
3234 offset += BytesPerInt;
3235 }
3236 assert((offset % unit) == 0, "");
3237
3238 // Initialize the remaining stuff, if any, with a ClearArray.
3239 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase);
3240 }
3241
3242 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
3243 Node* start_offset,
3244 Node* end_offset,
3245 PhaseGVN* phase) {
3246 if (start_offset == end_offset) {
3247 // nothing to do
3248 return mem;
3249 }
3250
3251 int unit = BytesPerLong;
3252 Node* zbase = start_offset;
3253 Node* zend = end_offset;
3254
3255 // Scale to the unit required by the CPU:
3256 if (!Matcher::init_array_count_is_in_bytes) {
3257 Node* shift = phase->intcon(exact_log2(unit));
3258 zbase = phase->transform(new URShiftXNode(zbase, shift) );
3259 zend = phase->transform(new URShiftXNode(zend, shift) );
3260 }
3261
3262 // Bulk clear double-words
3263 Node* zsize = phase->transform(new SubXNode(zend, zbase) );
3264 Node* adr = phase->transform(new AddPNode(dest, dest, start_offset) );
3265 mem = new ClearArrayNode(ctl, mem, zsize, adr, false);
3266 return phase->transform(mem);
3267 }
3268
3269 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
3270 intptr_t start_offset,
3271 intptr_t end_offset,
3272 PhaseGVN* phase) {
3273 if (start_offset == end_offset) {
3274 // nothing to do
3275 return mem;
3276 }
3277
3278 assert((end_offset % BytesPerInt) == 0, "odd end offset");
3279 intptr_t done_offset = end_offset;
3280 if ((done_offset % BytesPerLong) != 0) {
3281 done_offset -= BytesPerInt;
3282 }
3283 if (done_offset > start_offset) {
3284 mem = clear_memory(ctl, mem, dest,
3285 start_offset, phase->MakeConX(done_offset), phase);
3286 }
3287 if (done_offset < end_offset) { // emit the final 32-bit store
3288 Node* adr = new AddPNode(dest, dest, phase->MakeConX(done_offset));
3289 adr = phase->transform(adr);
3290 const TypePtr* atp = TypeRawPtr::BOTTOM;
3291 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
3292 mem = phase->transform(mem);
3293 done_offset += BytesPerInt;
3294 }
3295 assert(done_offset == end_offset, "");
3296 return mem;
3297 }
3298
3299 //=============================================================================
3300 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
3301 : MultiNode(TypeFunc::Parms + (precedent == nullptr? 0: 1)),
3302 _adr_type(C->get_adr_type(alias_idx)), _kind(Standalone)
3303 #ifdef ASSERT
3304 , _pair_idx(0)
3305 #endif
3306 {
3307 init_class_id(Class_MemBar);
3308 Node* top = C->top();
3309 init_req(TypeFunc::I_O,top);
3310 init_req(TypeFunc::FramePtr,top);
3311 init_req(TypeFunc::ReturnAdr,top);
3312 if (precedent != nullptr)
3313 init_req(TypeFunc::Parms, precedent);
3314 }
3315
3316 //------------------------------cmp--------------------------------------------
3317 uint MemBarNode::hash() const { return NO_HASH; }
3318 bool MemBarNode::cmp( const Node &n ) const {
3319 return (&n == this); // Always fail except on self
3320 }
3321
3322 //------------------------------make-------------------------------------------
3323 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
3324 switch (opcode) {
3325 case Op_MemBarAcquire: return new MemBarAcquireNode(C, atp, pn);
3326 case Op_LoadFence: return new LoadFenceNode(C, atp, pn);
3327 case Op_MemBarRelease: return new MemBarReleaseNode(C, atp, pn);
3328 case Op_StoreFence: return new StoreFenceNode(C, atp, pn);
3329 case Op_MemBarStoreStore: return new MemBarStoreStoreNode(C, atp, pn);
3330 case Op_StoreStoreFence: return new StoreStoreFenceNode(C, atp, pn);
3331 case Op_MemBarAcquireLock: return new MemBarAcquireLockNode(C, atp, pn);
3332 case Op_MemBarReleaseLock: return new MemBarReleaseLockNode(C, atp, pn);
3333 case Op_MemBarVolatile: return new MemBarVolatileNode(C, atp, pn);
3334 case Op_MemBarCPUOrder: return new MemBarCPUOrderNode(C, atp, pn);
3335 case Op_OnSpinWait: return new OnSpinWaitNode(C, atp, pn);
3336 case Op_Initialize: return new InitializeNode(C, atp, pn);
3337 default: ShouldNotReachHere(); return nullptr;
3338 }
3339 }
3340
3341 void MemBarNode::remove(PhaseIterGVN *igvn) {
3342 if (outcnt() != 2) {
3343 assert(Opcode() == Op_Initialize, "Only seen when there are no use of init memory");
3344 assert(outcnt() == 1, "Only control then");
3345 }
3346 if (trailing_store() || trailing_load_store()) {
3347 MemBarNode* leading = leading_membar();
3348 if (leading != nullptr) {
3349 assert(leading->trailing_membar() == this, "inconsistent leading/trailing membars");
3350 leading->remove(igvn);
3351 }
3352 }
3353 if (proj_out_or_null(TypeFunc::Memory) != nullptr) {
3354 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
3355 }
3356 if (proj_out_or_null(TypeFunc::Control) != nullptr) {
3357 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
3358 }
3359 }
3360
3361 //------------------------------Ideal------------------------------------------
3362 // Return a node which is more "ideal" than the current node. Strip out
3363 // control copies
3364 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3365 if (remove_dead_region(phase, can_reshape)) return this;
3366 // Don't bother trying to transform a dead node
3367 if (in(0) && in(0)->is_top()) {
3368 return nullptr;
3369 }
3370
3371 bool progress = false;
3372 // Eliminate volatile MemBars for scalar replaced objects.
3373 if (can_reshape && req() == (Precedent+1)) {
3374 bool eliminate = false;
3375 int opc = Opcode();
3376 if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) {
3377 // Volatile field loads and stores.
3378 Node* my_mem = in(MemBarNode::Precedent);
3379 // The MembarAquire may keep an unused LoadNode alive through the Precedent edge
3380 if ((my_mem != nullptr) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) {
3381 // if the Precedent is a decodeN and its input (a Load) is used at more than one place,
3382 // replace this Precedent (decodeN) with the Load instead.
3383 if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1)) {
3384 Node* load_node = my_mem->in(1);
3385 set_req(MemBarNode::Precedent, load_node);
3386 phase->is_IterGVN()->_worklist.push(my_mem);
3387 my_mem = load_node;
3388 } else {
3389 assert(my_mem->unique_out() == this, "sanity");
3390 assert(!trailing_load_store(), "load store node can't be eliminated");
3391 del_req(Precedent);
3392 phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later
3393 my_mem = nullptr;
3394 }
3395 progress = true;
3396 }
3397 if (my_mem != nullptr && my_mem->is_Mem()) {
3398 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
3399 // Check for scalar replaced object reference.
3400 if( t_oop != nullptr && t_oop->is_known_instance_field() &&
3401 t_oop->offset() != Type::OffsetBot &&
3402 t_oop->offset() != Type::OffsetTop) {
3403 eliminate = true;
3404 }
3405 }
3406 } else if (opc == Op_MemBarRelease) {
3407 // Final field stores.
3408 Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent), phase);
3409 if ((alloc != nullptr) && alloc->is_Allocate() &&
3410 alloc->as_Allocate()->does_not_escape_thread()) {
3411 // The allocated object does not escape.
3412 eliminate = true;
3413 }
3414 }
3415 if (eliminate) {
3416 // Replace MemBar projections by its inputs.
3417 PhaseIterGVN* igvn = phase->is_IterGVN();
3418 remove(igvn);
3419 // Must return either the original node (now dead) or a new node
3420 // (Do not return a top here, since that would break the uniqueness of top.)
3421 return new ConINode(TypeInt::ZERO);
3422 }
3423 }
3424 return progress ? this : nullptr;
3425 }
3426
3427 //------------------------------Value------------------------------------------
3428 const Type* MemBarNode::Value(PhaseGVN* phase) const {
3429 if( !in(0) ) return Type::TOP;
3430 if( phase->type(in(0)) == Type::TOP )
3431 return Type::TOP;
3432 return TypeTuple::MEMBAR;
3433 }
3434
3435 //------------------------------match------------------------------------------
3436 // Construct projections for memory.
3437 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) {
3438 switch (proj->_con) {
3439 case TypeFunc::Control:
3440 case TypeFunc::Memory:
3441 return new MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
3442 }
3443 ShouldNotReachHere();
3444 return nullptr;
3445 }
3446
3447 void MemBarNode::set_store_pair(MemBarNode* leading, MemBarNode* trailing) {
3448 trailing->_kind = TrailingStore;
3449 leading->_kind = LeadingStore;
3450 #ifdef ASSERT
3451 trailing->_pair_idx = leading->_idx;
3452 leading->_pair_idx = leading->_idx;
3453 #endif
3454 }
3455
3456 void MemBarNode::set_load_store_pair(MemBarNode* leading, MemBarNode* trailing) {
3457 trailing->_kind = TrailingLoadStore;
3458 leading->_kind = LeadingLoadStore;
3459 #ifdef ASSERT
3460 trailing->_pair_idx = leading->_idx;
3461 leading->_pair_idx = leading->_idx;
3462 #endif
3463 }
3464
3465 MemBarNode* MemBarNode::trailing_membar() const {
3466 ResourceMark rm;
3467 Node* trailing = (Node*)this;
3468 VectorSet seen;
3469 Node_Stack multis(0);
3470 do {
3471 Node* c = trailing;
3472 uint i = 0;
3473 do {
3474 trailing = nullptr;
3475 for (; i < c->outcnt(); i++) {
3476 Node* next = c->raw_out(i);
3477 if (next != c && next->is_CFG()) {
3478 if (c->is_MultiBranch()) {
3479 if (multis.node() == c) {
3480 multis.set_index(i+1);
3481 } else {
3482 multis.push(c, i+1);
3483 }
3484 }
3485 trailing = next;
3486 break;
3487 }
3488 }
3489 if (trailing != nullptr && !seen.test_set(trailing->_idx)) {
3490 break;
3491 }
3492 while (multis.size() > 0) {
3493 c = multis.node();
3494 i = multis.index();
3495 if (i < c->req()) {
3496 break;
3497 }
3498 multis.pop();
3499 }
3500 } while (multis.size() > 0);
3501 } while (!trailing->is_MemBar() || !trailing->as_MemBar()->trailing());
3502
3503 MemBarNode* mb = trailing->as_MemBar();
3504 assert((mb->_kind == TrailingStore && _kind == LeadingStore) ||
3505 (mb->_kind == TrailingLoadStore && _kind == LeadingLoadStore), "bad trailing membar");
3506 assert(mb->_pair_idx == _pair_idx, "bad trailing membar");
3507 return mb;
3508 }
3509
3510 MemBarNode* MemBarNode::leading_membar() const {
3511 ResourceMark rm;
3512 VectorSet seen;
3513 Node_Stack regions(0);
3514 Node* leading = in(0);
3515 while (leading != nullptr && (!leading->is_MemBar() || !leading->as_MemBar()->leading())) {
3516 while (leading == nullptr || leading->is_top() || seen.test_set(leading->_idx)) {
3517 leading = nullptr;
3518 while (regions.size() > 0 && leading == nullptr) {
3519 Node* r = regions.node();
3520 uint i = regions.index();
3521 if (i < r->req()) {
3522 leading = r->in(i);
3523 regions.set_index(i+1);
3524 } else {
3525 regions.pop();
3526 }
3527 }
3528 if (leading == nullptr) {
3529 assert(regions.size() == 0, "all paths should have been tried");
3530 return nullptr;
3531 }
3532 }
3533 if (leading->is_Region()) {
3534 regions.push(leading, 2);
3535 leading = leading->in(1);
3536 } else {
3537 leading = leading->in(0);
3538 }
3539 }
3540 #ifdef ASSERT
3541 Unique_Node_List wq;
3542 wq.push((Node*)this);
3543 uint found = 0;
3544 for (uint i = 0; i < wq.size(); i++) {
3545 Node* n = wq.at(i);
3546 if (n->is_Region()) {
3547 for (uint j = 1; j < n->req(); j++) {
3548 Node* in = n->in(j);
3549 if (in != nullptr && !in->is_top()) {
3550 wq.push(in);
3551 }
3552 }
3553 } else {
3554 if (n->is_MemBar() && n->as_MemBar()->leading()) {
3555 assert(n == leading, "consistency check failed");
3556 found++;
3557 } else {
3558 Node* in = n->in(0);
3559 if (in != nullptr && !in->is_top()) {
3560 wq.push(in);
3561 }
3562 }
3563 }
3564 }
3565 assert(found == 1 || (found == 0 && leading == nullptr), "consistency check failed");
3566 #endif
3567 if (leading == nullptr) {
3568 return nullptr;
3569 }
3570 MemBarNode* mb = leading->as_MemBar();
3571 assert((mb->_kind == LeadingStore && _kind == TrailingStore) ||
3572 (mb->_kind == LeadingLoadStore && _kind == TrailingLoadStore), "bad leading membar");
3573 assert(mb->_pair_idx == _pair_idx, "bad leading membar");
3574 return mb;
3575 }
3576
3577
3578 //===========================InitializeNode====================================
3579 // SUMMARY:
3580 // This node acts as a memory barrier on raw memory, after some raw stores.
3581 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
3582 // The Initialize can 'capture' suitably constrained stores as raw inits.
3583 // It can coalesce related raw stores into larger units (called 'tiles').
3584 // It can avoid zeroing new storage for memory units which have raw inits.
3585 // At macro-expansion, it is marked 'complete', and does not optimize further.
3586 //
3587 // EXAMPLE:
3588 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
3589 // ctl = incoming control; mem* = incoming memory
3590 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
3591 // First allocate uninitialized memory and fill in the header:
3592 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
3593 // ctl := alloc.Control; mem* := alloc.Memory*
3594 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
3595 // Then initialize to zero the non-header parts of the raw memory block:
3596 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
3597 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
3598 // After the initialize node executes, the object is ready for service:
3599 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
3600 // Suppose its body is immediately initialized as {1,2}:
3601 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3602 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3603 // mem.SLICE(#short[*]) := store2
3604 //
3605 // DETAILS:
3606 // An InitializeNode collects and isolates object initialization after
3607 // an AllocateNode and before the next possible safepoint. As a
3608 // memory barrier (MemBarNode), it keeps critical stores from drifting
3609 // down past any safepoint or any publication of the allocation.
3610 // Before this barrier, a newly-allocated object may have uninitialized bits.
3611 // After this barrier, it may be treated as a real oop, and GC is allowed.
3612 //
3613 // The semantics of the InitializeNode include an implicit zeroing of
3614 // the new object from object header to the end of the object.
3615 // (The object header and end are determined by the AllocateNode.)
3616 //
3617 // Certain stores may be added as direct inputs to the InitializeNode.
3618 // These stores must update raw memory, and they must be to addresses
3619 // derived from the raw address produced by AllocateNode, and with
3620 // a constant offset. They must be ordered by increasing offset.
3621 // The first one is at in(RawStores), the last at in(req()-1).
3622 // Unlike most memory operations, they are not linked in a chain,
3623 // but are displayed in parallel as users of the rawmem output of
3624 // the allocation.
3625 //
3626 // (See comments in InitializeNode::capture_store, which continue
3627 // the example given above.)
3628 //
3629 // When the associated Allocate is macro-expanded, the InitializeNode
3630 // may be rewritten to optimize collected stores. A ClearArrayNode
3631 // may also be created at that point to represent any required zeroing.
3632 // The InitializeNode is then marked 'complete', prohibiting further
3633 // capturing of nearby memory operations.
3634 //
3635 // During macro-expansion, all captured initializations which store
3636 // constant values of 32 bits or smaller are coalesced (if advantageous)
3637 // into larger 'tiles' 32 or 64 bits. This allows an object to be
3638 // initialized in fewer memory operations. Memory words which are
3639 // covered by neither tiles nor non-constant stores are pre-zeroed
3640 // by explicit stores of zero. (The code shape happens to do all
3641 // zeroing first, then all other stores, with both sequences occurring
3642 // in order of ascending offsets.)
3643 //
3644 // Alternatively, code may be inserted between an AllocateNode and its
3645 // InitializeNode, to perform arbitrary initialization of the new object.
3646 // E.g., the object copying intrinsics insert complex data transfers here.
3647 // The initialization must then be marked as 'complete' disable the
3648 // built-in zeroing semantics and the collection of initializing stores.
3649 //
3650 // While an InitializeNode is incomplete, reads from the memory state
3651 // produced by it are optimizable if they match the control edge and
3652 // new oop address associated with the allocation/initialization.
3653 // They return a stored value (if the offset matches) or else zero.
3654 // A write to the memory state, if it matches control and address,
3655 // and if it is to a constant offset, may be 'captured' by the
3656 // InitializeNode. It is cloned as a raw memory operation and rewired
3657 // inside the initialization, to the raw oop produced by the allocation.
3658 // Operations on addresses which are provably distinct (e.g., to
3659 // other AllocateNodes) are allowed to bypass the initialization.
3660 //
3661 // The effect of all this is to consolidate object initialization
3662 // (both arrays and non-arrays, both piecewise and bulk) into a
3663 // single location, where it can be optimized as a unit.
3664 //
3665 // Only stores with an offset less than TrackedInitializationLimit words
3666 // will be considered for capture by an InitializeNode. This puts a
3667 // reasonable limit on the complexity of optimized initializations.
3668
3669 //---------------------------InitializeNode------------------------------------
3670 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
3671 : MemBarNode(C, adr_type, rawoop),
3672 _is_complete(Incomplete), _does_not_escape(false)
3673 {
3674 init_class_id(Class_Initialize);
3675
3676 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
3677 assert(in(RawAddress) == rawoop, "proper init");
3678 // Note: allocation() can be null, for secondary initialization barriers
3679 }
3680
3681 // Since this node is not matched, it will be processed by the
3682 // register allocator. Declare that there are no constraints
3683 // on the allocation of the RawAddress edge.
3684 const RegMask &InitializeNode::in_RegMask(uint idx) const {
3685 // This edge should be set to top, by the set_complete. But be conservative.
3686 if (idx == InitializeNode::RawAddress)
3687 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
3688 return RegMask::Empty;
3689 }
3690
3691 Node* InitializeNode::memory(uint alias_idx) {
3692 Node* mem = in(Memory);
3693 if (mem->is_MergeMem()) {
3694 return mem->as_MergeMem()->memory_at(alias_idx);
3695 } else {
3696 // incoming raw memory is not split
3697 return mem;
3698 }
3699 }
3700
3701 bool InitializeNode::is_non_zero() {
3702 if (is_complete()) return false;
3703 remove_extra_zeroes();
3704 return (req() > RawStores);
3705 }
3706
3707 void InitializeNode::set_complete(PhaseGVN* phase) {
3708 assert(!is_complete(), "caller responsibility");
3709 _is_complete = Complete;
3710
3711 // After this node is complete, it contains a bunch of
3712 // raw-memory initializations. There is no need for
3713 // it to have anything to do with non-raw memory effects.
3714 // Therefore, tell all non-raw users to re-optimize themselves,
3715 // after skipping the memory effects of this initialization.
3716 PhaseIterGVN* igvn = phase->is_IterGVN();
3717 if (igvn) igvn->add_users_to_worklist(this);
3718 }
3719
3720 // convenience function
3721 // return false if the init contains any stores already
3722 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
3723 InitializeNode* init = initialization();
3724 if (init == nullptr || init->is_complete()) return false;
3725 init->remove_extra_zeroes();
3726 // for now, if this allocation has already collected any inits, bail:
3727 if (init->is_non_zero()) return false;
3728 init->set_complete(phase);
3729 return true;
3730 }
3731
3732 void InitializeNode::remove_extra_zeroes() {
3733 if (req() == RawStores) return;
3734 Node* zmem = zero_memory();
3735 uint fill = RawStores;
3736 for (uint i = fill; i < req(); i++) {
3737 Node* n = in(i);
3738 if (n->is_top() || n == zmem) continue; // skip
3739 if (fill < i) set_req(fill, n); // compact
3740 ++fill;
3741 }
3742 // delete any empty spaces created:
3743 while (fill < req()) {
3744 del_req(fill);
3745 }
3746 }
3747
3748 // Helper for remembering which stores go with which offsets.
3749 intptr_t InitializeNode::get_store_offset(Node* st, PhaseValues* phase) {
3750 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
3751 intptr_t offset = -1;
3752 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
3753 phase, offset);
3754 if (base == nullptr) return -1; // something is dead,
3755 if (offset < 0) return -1; // dead, dead
3756 return offset;
3757 }
3758
3759 // Helper for proving that an initialization expression is
3760 // "simple enough" to be folded into an object initialization.
3761 // Attempts to prove that a store's initial value 'n' can be captured
3762 // within the initialization without creating a vicious cycle, such as:
3763 // { Foo p = new Foo(); p.next = p; }
3764 // True for constants and parameters and small combinations thereof.
3765 bool InitializeNode::detect_init_independence(Node* value, PhaseGVN* phase) {
3766 ResourceMark rm;
3767 Unique_Node_List worklist;
3768 worklist.push(value);
3769
3770 uint complexity_limit = 20;
3771 for (uint j = 0; j < worklist.size(); j++) {
3772 if (j >= complexity_limit) {
3773 return false; // Bail out if processed too many nodes
3774 }
3775
3776 Node* n = worklist.at(j);
3777 if (n == nullptr) continue; // (can this really happen?)
3778 if (n->is_Proj()) n = n->in(0);
3779 if (n == this) return false; // found a cycle
3780 if (n->is_Con()) continue;
3781 if (n->is_Start()) continue; // params, etc., are OK
3782 if (n->is_Root()) continue; // even better
3783
3784 // There cannot be any dependency if 'n' is a CFG node that dominates the current allocation
3785 if (n->is_CFG() && phase->is_dominator(n, allocation())) {
3786 continue;
3787 }
3788
3789 Node* ctl = n->in(0);
3790 if (ctl != nullptr && !ctl->is_top()) {
3791 if (ctl->is_Proj()) ctl = ctl->in(0);
3792 if (ctl == this) return false;
3793
3794 // If we already know that the enclosing memory op is pinned right after
3795 // the init, then any control flow that the store has picked up
3796 // must have preceded the init, or else be equal to the init.
3797 // Even after loop optimizations (which might change control edges)
3798 // a store is never pinned *before* the availability of its inputs.
3799 if (!MemNode::all_controls_dominate(n, this))
3800 return false; // failed to prove a good control
3801 }
3802
3803 // Check data edges for possible dependencies on 'this'.
3804 for (uint i = 1; i < n->req(); i++) {
3805 Node* m = n->in(i);
3806 if (m == nullptr || m == n || m->is_top()) continue;
3807
3808 // Only process data inputs once
3809 worklist.push(m);
3810 }
3811 }
3812
3813 return true;
3814 }
3815
3816 // Here are all the checks a Store must pass before it can be moved into
3817 // an initialization. Returns zero if a check fails.
3818 // On success, returns the (constant) offset to which the store applies,
3819 // within the initialized memory.
3820 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseGVN* phase, bool can_reshape) {
3821 const int FAIL = 0;
3822 if (st->req() != MemNode::ValueIn + 1)
3823 return FAIL; // an inscrutable StoreNode (card mark?)
3824 Node* ctl = st->in(MemNode::Control);
3825 if (!(ctl != nullptr && ctl->is_Proj() && ctl->in(0) == this))
3826 return FAIL; // must be unconditional after the initialization
3827 Node* mem = st->in(MemNode::Memory);
3828 if (!(mem->is_Proj() && mem->in(0) == this))
3829 return FAIL; // must not be preceded by other stores
3830 Node* adr = st->in(MemNode::Address);
3831 intptr_t offset;
3832 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
3833 if (alloc == nullptr)
3834 return FAIL; // inscrutable address
3835 if (alloc != allocation())
3836 return FAIL; // wrong allocation! (store needs to float up)
3837 int size_in_bytes = st->memory_size();
3838 if ((size_in_bytes != 0) && (offset % size_in_bytes) != 0) {
3839 return FAIL; // mismatched access
3840 }
3841 Node* val = st->in(MemNode::ValueIn);
3842
3843 if (!detect_init_independence(val, phase))
3844 return FAIL; // stored value must be 'simple enough'
3845
3846 // The Store can be captured only if nothing after the allocation
3847 // and before the Store is using the memory location that the store
3848 // overwrites.
3849 bool failed = false;
3850 // If is_complete_with_arraycopy() is true the shape of the graph is
3851 // well defined and is safe so no need for extra checks.
3852 if (!is_complete_with_arraycopy()) {
3853 // We are going to look at each use of the memory state following
3854 // the allocation to make sure nothing reads the memory that the
3855 // Store writes.
3856 const TypePtr* t_adr = phase->type(adr)->isa_ptr();
3857 int alias_idx = phase->C->get_alias_index(t_adr);
3858 ResourceMark rm;
3859 Unique_Node_List mems;
3860 mems.push(mem);
3861 Node* unique_merge = nullptr;
3862 for (uint next = 0; next < mems.size(); ++next) {
3863 Node *m = mems.at(next);
3864 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
3865 Node *n = m->fast_out(j);
3866 if (n->outcnt() == 0) {
3867 continue;
3868 }
3869 if (n == st) {
3870 continue;
3871 } else if (n->in(0) != nullptr && n->in(0) != ctl) {
3872 // If the control of this use is different from the control
3873 // of the Store which is right after the InitializeNode then
3874 // this node cannot be between the InitializeNode and the
3875 // Store.
3876 continue;
3877 } else if (n->is_MergeMem()) {
3878 if (n->as_MergeMem()->memory_at(alias_idx) == m) {
3879 // We can hit a MergeMemNode (that will likely go away
3880 // later) that is a direct use of the memory state
3881 // following the InitializeNode on the same slice as the
3882 // store node that we'd like to capture. We need to check
3883 // the uses of the MergeMemNode.
3884 mems.push(n);
3885 }
3886 } else if (n->is_Mem()) {
3887 Node* other_adr = n->in(MemNode::Address);
3888 if (other_adr == adr) {
3889 failed = true;
3890 break;
3891 } else {
3892 const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr();
3893 if (other_t_adr != nullptr) {
3894 int other_alias_idx = phase->C->get_alias_index(other_t_adr);
3895 if (other_alias_idx == alias_idx) {
3896 // A load from the same memory slice as the store right
3897 // after the InitializeNode. We check the control of the
3898 // object/array that is loaded from. If it's the same as
3899 // the store control then we cannot capture the store.
3900 assert(!n->is_Store(), "2 stores to same slice on same control?");
3901 Node* base = other_adr;
3902 assert(base->is_AddP(), "should be addp but is %s", base->Name());
3903 base = base->in(AddPNode::Base);
3904 if (base != nullptr) {
3905 base = base->uncast();
3906 if (base->is_Proj() && base->in(0) == alloc) {
3907 failed = true;
3908 break;
3909 }
3910 }
3911 }
3912 }
3913 }
3914 } else {
3915 failed = true;
3916 break;
3917 }
3918 }
3919 }
3920 }
3921 if (failed) {
3922 if (!can_reshape) {
3923 // We decided we couldn't capture the store during parsing. We
3924 // should try again during the next IGVN once the graph is
3925 // cleaner.
3926 phase->C->record_for_igvn(st);
3927 }
3928 return FAIL;
3929 }
3930
3931 return offset; // success
3932 }
3933
3934 // Find the captured store in(i) which corresponds to the range
3935 // [start..start+size) in the initialized object.
3936 // If there is one, return its index i. If there isn't, return the
3937 // negative of the index where it should be inserted.
3938 // Return 0 if the queried range overlaps an initialization boundary
3939 // or if dead code is encountered.
3940 // If size_in_bytes is zero, do not bother with overlap checks.
3941 int InitializeNode::captured_store_insertion_point(intptr_t start,
3942 int size_in_bytes,
3943 PhaseValues* phase) {
3944 const int FAIL = 0, MAX_STORE = MAX2(BytesPerLong, (int)MaxVectorSize);
3945
3946 if (is_complete())
3947 return FAIL; // arraycopy got here first; punt
3948
3949 assert(allocation() != nullptr, "must be present");
3950
3951 // no negatives, no header fields:
3952 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
3953
3954 // after a certain size, we bail out on tracking all the stores:
3955 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3956 if (start >= ti_limit) return FAIL;
3957
3958 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
3959 if (i >= limit) return -(int)i; // not found; here is where to put it
3960
3961 Node* st = in(i);
3962 intptr_t st_off = get_store_offset(st, phase);
3963 if (st_off < 0) {
3964 if (st != zero_memory()) {
3965 return FAIL; // bail out if there is dead garbage
3966 }
3967 } else if (st_off > start) {
3968 // ...we are done, since stores are ordered
3969 if (st_off < start + size_in_bytes) {
3970 return FAIL; // the next store overlaps
3971 }
3972 return -(int)i; // not found; here is where to put it
3973 } else if (st_off < start) {
3974 assert(st->as_Store()->memory_size() <= MAX_STORE, "");
3975 if (size_in_bytes != 0 &&
3976 start < st_off + MAX_STORE &&
3977 start < st_off + st->as_Store()->memory_size()) {
3978 return FAIL; // the previous store overlaps
3979 }
3980 } else {
3981 if (size_in_bytes != 0 &&
3982 st->as_Store()->memory_size() != size_in_bytes) {
3983 return FAIL; // mismatched store size
3984 }
3985 return i;
3986 }
3987
3988 ++i;
3989 }
3990 }
3991
3992 // Look for a captured store which initializes at the offset 'start'
3993 // with the given size. If there is no such store, and no other
3994 // initialization interferes, then return zero_memory (the memory
3995 // projection of the AllocateNode).
3996 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
3997 PhaseValues* phase) {
3998 assert(stores_are_sane(phase), "");
3999 int i = captured_store_insertion_point(start, size_in_bytes, phase);
4000 if (i == 0) {
4001 return nullptr; // something is dead
4002 } else if (i < 0) {
4003 return zero_memory(); // just primordial zero bits here
4004 } else {
4005 Node* st = in(i); // here is the store at this position
4006 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
4007 return st;
4008 }
4009 }
4010
4011 // Create, as a raw pointer, an address within my new object at 'offset'.
4012 Node* InitializeNode::make_raw_address(intptr_t offset,
4013 PhaseGVN* phase) {
4014 Node* addr = in(RawAddress);
4015 if (offset != 0) {
4016 Compile* C = phase->C;
4017 addr = phase->transform( new AddPNode(C->top(), addr,
4018 phase->MakeConX(offset)) );
4019 }
4020 return addr;
4021 }
4022
4023 // Clone the given store, converting it into a raw store
4024 // initializing a field or element of my new object.
4025 // Caller is responsible for retiring the original store,
4026 // with subsume_node or the like.
4027 //
4028 // From the example above InitializeNode::InitializeNode,
4029 // here are the old stores to be captured:
4030 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
4031 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
4032 //
4033 // Here is the changed code; note the extra edges on init:
4034 // alloc = (Allocate ...)
4035 // rawoop = alloc.RawAddress
4036 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
4037 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
4038 // init = (Initialize alloc.Control alloc.Memory rawoop
4039 // rawstore1 rawstore2)
4040 //
4041 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
4042 PhaseGVN* phase, bool can_reshape) {
4043 assert(stores_are_sane(phase), "");
4044
4045 if (start < 0) return nullptr;
4046 assert(can_capture_store(st, phase, can_reshape) == start, "sanity");
4047
4048 Compile* C = phase->C;
4049 int size_in_bytes = st->memory_size();
4050 int i = captured_store_insertion_point(start, size_in_bytes, phase);
4051 if (i == 0) return nullptr; // bail out
4052 Node* prev_mem = nullptr; // raw memory for the captured store
4053 if (i > 0) {
4054 prev_mem = in(i); // there is a pre-existing store under this one
4055 set_req(i, C->top()); // temporarily disconnect it
4056 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
4057 } else {
4058 i = -i; // no pre-existing store
4059 prev_mem = zero_memory(); // a slice of the newly allocated object
4060 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
4061 set_req(--i, C->top()); // reuse this edge; it has been folded away
4062 else
4063 ins_req(i, C->top()); // build a new edge
4064 }
4065 Node* new_st = st->clone();
4066 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
4067 new_st->set_req(MemNode::Control, in(Control));
4068 new_st->set_req(MemNode::Memory, prev_mem);
4069 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
4070 bs->eliminate_gc_barrier_data(new_st);
4071 new_st = phase->transform(new_st);
4072
4073 // At this point, new_st might have swallowed a pre-existing store
4074 // at the same offset, or perhaps new_st might have disappeared,
4075 // if it redundantly stored the same value (or zero to fresh memory).
4076
4077 // In any case, wire it in:
4078 PhaseIterGVN* igvn = phase->is_IterGVN();
4079 if (igvn) {
4080 igvn->rehash_node_delayed(this);
4081 }
4082 set_req(i, new_st);
4083
4084 // The caller may now kill the old guy.
4085 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
4086 assert(check_st == new_st || check_st == nullptr, "must be findable");
4087 assert(!is_complete(), "");
4088 return new_st;
4089 }
4090
4091 static bool store_constant(jlong* tiles, int num_tiles,
4092 intptr_t st_off, int st_size,
4093 jlong con) {
4094 if ((st_off & (st_size-1)) != 0)
4095 return false; // strange store offset (assume size==2**N)
4096 address addr = (address)tiles + st_off;
4097 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
4098 switch (st_size) {
4099 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
4100 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
4101 case sizeof(jint): *(jint*) addr = (jint) con; break;
4102 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
4103 default: return false; // strange store size (detect size!=2**N here)
4104 }
4105 return true; // return success to caller
4106 }
4107
4108 // Coalesce subword constants into int constants and possibly
4109 // into long constants. The goal, if the CPU permits,
4110 // is to initialize the object with a small number of 64-bit tiles.
4111 // Also, convert floating-point constants to bit patterns.
4112 // Non-constants are not relevant to this pass.
4113 //
4114 // In terms of the running example on InitializeNode::InitializeNode
4115 // and InitializeNode::capture_store, here is the transformation
4116 // of rawstore1 and rawstore2 into rawstore12:
4117 // alloc = (Allocate ...)
4118 // rawoop = alloc.RawAddress
4119 // tile12 = 0x00010002
4120 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
4121 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
4122 //
4123 void
4124 InitializeNode::coalesce_subword_stores(intptr_t header_size,
4125 Node* size_in_bytes,
4126 PhaseGVN* phase) {
4127 Compile* C = phase->C;
4128
4129 assert(stores_are_sane(phase), "");
4130 // Note: After this pass, they are not completely sane,
4131 // since there may be some overlaps.
4132
4133 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
4134
4135 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
4136 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
4137 size_limit = MIN2(size_limit, ti_limit);
4138 size_limit = align_up(size_limit, BytesPerLong);
4139 int num_tiles = size_limit / BytesPerLong;
4140
4141 // allocate space for the tile map:
4142 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
4143 jlong tiles_buf[small_len];
4144 Node* nodes_buf[small_len];
4145 jlong inits_buf[small_len];
4146 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
4147 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
4148 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
4149 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
4150 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
4151 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
4152 // tiles: exact bitwise model of all primitive constants
4153 // nodes: last constant-storing node subsumed into the tiles model
4154 // inits: which bytes (in each tile) are touched by any initializations
4155
4156 //// Pass A: Fill in the tile model with any relevant stores.
4157
4158 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
4159 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
4160 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
4161 Node* zmem = zero_memory(); // initially zero memory state
4162 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
4163 Node* st = in(i);
4164 intptr_t st_off = get_store_offset(st, phase);
4165
4166 // Figure out the store's offset and constant value:
4167 if (st_off < header_size) continue; //skip (ignore header)
4168 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
4169 int st_size = st->as_Store()->memory_size();
4170 if (st_off + st_size > size_limit) break;
4171
4172 // Record which bytes are touched, whether by constant or not.
4173 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
4174 continue; // skip (strange store size)
4175
4176 const Type* val = phase->type(st->in(MemNode::ValueIn));
4177 if (!val->singleton()) continue; //skip (non-con store)
4178 BasicType type = val->basic_type();
4179
4180 jlong con = 0;
4181 switch (type) {
4182 case T_INT: con = val->is_int()->get_con(); break;
4183 case T_LONG: con = val->is_long()->get_con(); break;
4184 case T_FLOAT: con = jint_cast(val->getf()); break;
4185 case T_DOUBLE: con = jlong_cast(val->getd()); break;
4186 default: continue; //skip (odd store type)
4187 }
4188
4189 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
4190 st->Opcode() == Op_StoreL) {
4191 continue; // This StoreL is already optimal.
4192 }
4193
4194 // Store down the constant.
4195 store_constant(tiles, num_tiles, st_off, st_size, con);
4196
4197 intptr_t j = st_off >> LogBytesPerLong;
4198
4199 if (type == T_INT && st_size == BytesPerInt
4200 && (st_off & BytesPerInt) == BytesPerInt) {
4201 jlong lcon = tiles[j];
4202 if (!Matcher::isSimpleConstant64(lcon) &&
4203 st->Opcode() == Op_StoreI) {
4204 // This StoreI is already optimal by itself.
4205 jint* intcon = (jint*) &tiles[j];
4206 intcon[1] = 0; // undo the store_constant()
4207
4208 // If the previous store is also optimal by itself, back up and
4209 // undo the action of the previous loop iteration... if we can.
4210 // But if we can't, just let the previous half take care of itself.
4211 st = nodes[j];
4212 st_off -= BytesPerInt;
4213 con = intcon[0];
4214 if (con != 0 && st != nullptr && st->Opcode() == Op_StoreI) {
4215 assert(st_off >= header_size, "still ignoring header");
4216 assert(get_store_offset(st, phase) == st_off, "must be");
4217 assert(in(i-1) == zmem, "must be");
4218 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
4219 assert(con == tcon->is_int()->get_con(), "must be");
4220 // Undo the effects of the previous loop trip, which swallowed st:
4221 intcon[0] = 0; // undo store_constant()
4222 set_req(i-1, st); // undo set_req(i, zmem)
4223 nodes[j] = nullptr; // undo nodes[j] = st
4224 --old_subword; // undo ++old_subword
4225 }
4226 continue; // This StoreI is already optimal.
4227 }
4228 }
4229
4230 // This store is not needed.
4231 set_req(i, zmem);
4232 nodes[j] = st; // record for the moment
4233 if (st_size < BytesPerLong) // something has changed
4234 ++old_subword; // includes int/float, but who's counting...
4235 else ++old_long;
4236 }
4237
4238 if ((old_subword + old_long) == 0)
4239 return; // nothing more to do
4240
4241 //// Pass B: Convert any non-zero tiles into optimal constant stores.
4242 // Be sure to insert them before overlapping non-constant stores.
4243 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
4244 for (int j = 0; j < num_tiles; j++) {
4245 jlong con = tiles[j];
4246 jlong init = inits[j];
4247 if (con == 0) continue;
4248 jint con0, con1; // split the constant, address-wise
4249 jint init0, init1; // split the init map, address-wise
4250 { union { jlong con; jint intcon[2]; } u;
4251 u.con = con;
4252 con0 = u.intcon[0];
4253 con1 = u.intcon[1];
4254 u.con = init;
4255 init0 = u.intcon[0];
4256 init1 = u.intcon[1];
4257 }
4258
4259 Node* old = nodes[j];
4260 assert(old != nullptr, "need the prior store");
4261 intptr_t offset = (j * BytesPerLong);
4262
4263 bool split = !Matcher::isSimpleConstant64(con);
4264
4265 if (offset < header_size) {
4266 assert(offset + BytesPerInt >= header_size, "second int counts");
4267 assert(*(jint*)&tiles[j] == 0, "junk in header");
4268 split = true; // only the second word counts
4269 // Example: int a[] = { 42 ... }
4270 } else if (con0 == 0 && init0 == -1) {
4271 split = true; // first word is covered by full inits
4272 // Example: int a[] = { ... foo(), 42 ... }
4273 } else if (con1 == 0 && init1 == -1) {
4274 split = true; // second word is covered by full inits
4275 // Example: int a[] = { ... 42, foo() ... }
4276 }
4277
4278 // Here's a case where init0 is neither 0 nor -1:
4279 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
4280 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
4281 // In this case the tile is not split; it is (jlong)42.
4282 // The big tile is stored down, and then the foo() value is inserted.
4283 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
4284
4285 Node* ctl = old->in(MemNode::Control);
4286 Node* adr = make_raw_address(offset, phase);
4287 const TypePtr* atp = TypeRawPtr::BOTTOM;
4288
4289 // One or two coalesced stores to plop down.
4290 Node* st[2];
4291 intptr_t off[2];
4292 int nst = 0;
4293 if (!split) {
4294 ++new_long;
4295 off[nst] = offset;
4296 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
4297 phase->longcon(con), T_LONG, MemNode::unordered);
4298 } else {
4299 // Omit either if it is a zero.
4300 if (con0 != 0) {
4301 ++new_int;
4302 off[nst] = offset;
4303 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
4304 phase->intcon(con0), T_INT, MemNode::unordered);
4305 }
4306 if (con1 != 0) {
4307 ++new_int;
4308 offset += BytesPerInt;
4309 adr = make_raw_address(offset, phase);
4310 off[nst] = offset;
4311 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
4312 phase->intcon(con1), T_INT, MemNode::unordered);
4313 }
4314 }
4315
4316 // Insert second store first, then the first before the second.
4317 // Insert each one just before any overlapping non-constant stores.
4318 while (nst > 0) {
4319 Node* st1 = st[--nst];
4320 C->copy_node_notes_to(st1, old);
4321 st1 = phase->transform(st1);
4322 offset = off[nst];
4323 assert(offset >= header_size, "do not smash header");
4324 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
4325 guarantee(ins_idx != 0, "must re-insert constant store");
4326 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
4327 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
4328 set_req(--ins_idx, st1);
4329 else
4330 ins_req(ins_idx, st1);
4331 }
4332 }
4333
4334 if (PrintCompilation && WizardMode)
4335 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
4336 old_subword, old_long, new_int, new_long);
4337 if (C->log() != nullptr)
4338 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
4339 old_subword, old_long, new_int, new_long);
4340
4341 // Clean up any remaining occurrences of zmem:
4342 remove_extra_zeroes();
4343 }
4344
4345 // Explore forward from in(start) to find the first fully initialized
4346 // word, and return its offset. Skip groups of subword stores which
4347 // together initialize full words. If in(start) is itself part of a
4348 // fully initialized word, return the offset of in(start). If there
4349 // are no following full-word stores, or if something is fishy, return
4350 // a negative value.
4351 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
4352 int int_map = 0;
4353 intptr_t int_map_off = 0;
4354 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
4355
4356 for (uint i = start, limit = req(); i < limit; i++) {
4357 Node* st = in(i);
4358
4359 intptr_t st_off = get_store_offset(st, phase);
4360 if (st_off < 0) break; // return conservative answer
4361
4362 int st_size = st->as_Store()->memory_size();
4363 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
4364 return st_off; // we found a complete word init
4365 }
4366
4367 // update the map:
4368
4369 intptr_t this_int_off = align_down(st_off, BytesPerInt);
4370 if (this_int_off != int_map_off) {
4371 // reset the map:
4372 int_map = 0;
4373 int_map_off = this_int_off;
4374 }
4375
4376 int subword_off = st_off - this_int_off;
4377 int_map |= right_n_bits(st_size) << subword_off;
4378 if ((int_map & FULL_MAP) == FULL_MAP) {
4379 return this_int_off; // we found a complete word init
4380 }
4381
4382 // Did this store hit or cross the word boundary?
4383 intptr_t next_int_off = align_down(st_off + st_size, BytesPerInt);
4384 if (next_int_off == this_int_off + BytesPerInt) {
4385 // We passed the current int, without fully initializing it.
4386 int_map_off = next_int_off;
4387 int_map >>= BytesPerInt;
4388 } else if (next_int_off > this_int_off + BytesPerInt) {
4389 // We passed the current and next int.
4390 return this_int_off + BytesPerInt;
4391 }
4392 }
4393
4394 return -1;
4395 }
4396
4397
4398 // Called when the associated AllocateNode is expanded into CFG.
4399 // At this point, we may perform additional optimizations.
4400 // Linearize the stores by ascending offset, to make memory
4401 // activity as coherent as possible.
4402 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
4403 intptr_t header_size,
4404 Node* size_in_bytes,
4405 PhaseIterGVN* phase) {
4406 assert(!is_complete(), "not already complete");
4407 assert(stores_are_sane(phase), "");
4408 assert(allocation() != nullptr, "must be present");
4409
4410 remove_extra_zeroes();
4411
4412 if (ReduceFieldZeroing || ReduceBulkZeroing)
4413 // reduce instruction count for common initialization patterns
4414 coalesce_subword_stores(header_size, size_in_bytes, phase);
4415
4416 Node* zmem = zero_memory(); // initially zero memory state
4417 Node* inits = zmem; // accumulating a linearized chain of inits
4418 #ifdef ASSERT
4419 intptr_t first_offset = allocation()->minimum_header_size();
4420 intptr_t last_init_off = first_offset; // previous init offset
4421 intptr_t last_init_end = first_offset; // previous init offset+size
4422 intptr_t last_tile_end = first_offset; // previous tile offset+size
4423 #endif
4424 intptr_t zeroes_done = header_size;
4425
4426 bool do_zeroing = true; // we might give up if inits are very sparse
4427 int big_init_gaps = 0; // how many large gaps have we seen?
4428
4429 if (UseTLAB && ZeroTLAB) do_zeroing = false;
4430 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
4431
4432 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
4433 Node* st = in(i);
4434 intptr_t st_off = get_store_offset(st, phase);
4435 if (st_off < 0)
4436 break; // unknown junk in the inits
4437 if (st->in(MemNode::Memory) != zmem)
4438 break; // complicated store chains somehow in list
4439
4440 int st_size = st->as_Store()->memory_size();
4441 intptr_t next_init_off = st_off + st_size;
4442
4443 if (do_zeroing && zeroes_done < next_init_off) {
4444 // See if this store needs a zero before it or under it.
4445 intptr_t zeroes_needed = st_off;
4446
4447 if (st_size < BytesPerInt) {
4448 // Look for subword stores which only partially initialize words.
4449 // If we find some, we must lay down some word-level zeroes first,
4450 // underneath the subword stores.
4451 //
4452 // Examples:
4453 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
4454 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
4455 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
4456 //
4457 // Note: coalesce_subword_stores may have already done this,
4458 // if it was prompted by constant non-zero subword initializers.
4459 // But this case can still arise with non-constant stores.
4460
4461 intptr_t next_full_store = find_next_fullword_store(i, phase);
4462
4463 // In the examples above:
4464 // in(i) p q r s x y z
4465 // st_off 12 13 14 15 12 13 14
4466 // st_size 1 1 1 1 1 1 1
4467 // next_full_s. 12 16 16 16 16 16 16
4468 // z's_done 12 16 16 16 12 16 12
4469 // z's_needed 12 16 16 16 16 16 16
4470 // zsize 0 0 0 0 4 0 4
4471 if (next_full_store < 0) {
4472 // Conservative tack: Zero to end of current word.
4473 zeroes_needed = align_up(zeroes_needed, BytesPerInt);
4474 } else {
4475 // Zero to beginning of next fully initialized word.
4476 // Or, don't zero at all, if we are already in that word.
4477 assert(next_full_store >= zeroes_needed, "must go forward");
4478 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
4479 zeroes_needed = next_full_store;
4480 }
4481 }
4482
4483 if (zeroes_needed > zeroes_done) {
4484 intptr_t zsize = zeroes_needed - zeroes_done;
4485 // Do some incremental zeroing on rawmem, in parallel with inits.
4486 zeroes_done = align_down(zeroes_done, BytesPerInt);
4487 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
4488 zeroes_done, zeroes_needed,
4489 phase);
4490 zeroes_done = zeroes_needed;
4491 if (zsize > InitArrayShortSize && ++big_init_gaps > 2)
4492 do_zeroing = false; // leave the hole, next time
4493 }
4494 }
4495
4496 // Collect the store and move on:
4497 phase->replace_input_of(st, MemNode::Memory, inits);
4498 inits = st; // put it on the linearized chain
4499 set_req(i, zmem); // unhook from previous position
4500
4501 if (zeroes_done == st_off)
4502 zeroes_done = next_init_off;
4503
4504 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
4505
4506 #ifdef ASSERT
4507 // Various order invariants. Weaker than stores_are_sane because
4508 // a large constant tile can be filled in by smaller non-constant stores.
4509 assert(st_off >= last_init_off, "inits do not reverse");
4510 last_init_off = st_off;
4511 const Type* val = nullptr;
4512 if (st_size >= BytesPerInt &&
4513 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
4514 (int)val->basic_type() < (int)T_OBJECT) {
4515 assert(st_off >= last_tile_end, "tiles do not overlap");
4516 assert(st_off >= last_init_end, "tiles do not overwrite inits");
4517 last_tile_end = MAX2(last_tile_end, next_init_off);
4518 } else {
4519 intptr_t st_tile_end = align_up(next_init_off, BytesPerLong);
4520 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
4521 assert(st_off >= last_init_end, "inits do not overlap");
4522 last_init_end = next_init_off; // it's a non-tile
4523 }
4524 #endif //ASSERT
4525 }
4526
4527 remove_extra_zeroes(); // clear out all the zmems left over
4528 add_req(inits);
4529
4530 if (!(UseTLAB && ZeroTLAB)) {
4531 // If anything remains to be zeroed, zero it all now.
4532 zeroes_done = align_down(zeroes_done, BytesPerInt);
4533 // if it is the last unused 4 bytes of an instance, forget about it
4534 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
4535 if (zeroes_done + BytesPerLong >= size_limit) {
4536 AllocateNode* alloc = allocation();
4537 assert(alloc != nullptr, "must be present");
4538 if (alloc != nullptr && alloc->Opcode() == Op_Allocate) {
4539 Node* klass_node = alloc->in(AllocateNode::KlassNode);
4540 ciKlass* k = phase->type(klass_node)->is_instklassptr()->instance_klass();
4541 if (zeroes_done == k->layout_helper())
4542 zeroes_done = size_limit;
4543 }
4544 }
4545 if (zeroes_done < size_limit) {
4546 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
4547 zeroes_done, size_in_bytes, phase);
4548 }
4549 }
4550
4551 set_complete(phase);
4552 return rawmem;
4553 }
4554
4555
4556 #ifdef ASSERT
4557 bool InitializeNode::stores_are_sane(PhaseValues* phase) {
4558 if (is_complete())
4559 return true; // stores could be anything at this point
4560 assert(allocation() != nullptr, "must be present");
4561 intptr_t last_off = allocation()->minimum_header_size();
4562 for (uint i = InitializeNode::RawStores; i < req(); i++) {
4563 Node* st = in(i);
4564 intptr_t st_off = get_store_offset(st, phase);
4565 if (st_off < 0) continue; // ignore dead garbage
4566 if (last_off > st_off) {
4567 tty->print_cr("*** bad store offset at %d: " INTX_FORMAT " > " INTX_FORMAT, i, last_off, st_off);
4568 this->dump(2);
4569 assert(false, "ascending store offsets");
4570 return false;
4571 }
4572 last_off = st_off + st->as_Store()->memory_size();
4573 }
4574 return true;
4575 }
4576 #endif //ASSERT
4577
4578
4579
4580
4581 //============================MergeMemNode=====================================
4582 //
4583 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
4584 // contributing store or call operations. Each contributor provides the memory
4585 // state for a particular "alias type" (see Compile::alias_type). For example,
4586 // if a MergeMem has an input X for alias category #6, then any memory reference
4587 // to alias category #6 may use X as its memory state input, as an exact equivalent
4588 // to using the MergeMem as a whole.
4589 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
4590 //
4591 // (Here, the <N> notation gives the index of the relevant adr_type.)
4592 //
4593 // In one special case (and more cases in the future), alias categories overlap.
4594 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
4595 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
4596 // it is exactly equivalent to that state W:
4597 // MergeMem(<Bot>: W) <==> W
4598 //
4599 // Usually, the merge has more than one input. In that case, where inputs
4600 // overlap (i.e., one is Bot), the narrower alias type determines the memory
4601 // state for that type, and the wider alias type (Bot) fills in everywhere else:
4602 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
4603 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
4604 //
4605 // A merge can take a "wide" memory state as one of its narrow inputs.
4606 // This simply means that the merge observes out only the relevant parts of
4607 // the wide input. That is, wide memory states arriving at narrow merge inputs
4608 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
4609 //
4610 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
4611 // and that memory slices "leak through":
4612 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
4613 //
4614 // But, in such a cascade, repeated memory slices can "block the leak":
4615 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
4616 //
4617 // In the last example, Y is not part of the combined memory state of the
4618 // outermost MergeMem. The system must, of course, prevent unschedulable
4619 // memory states from arising, so you can be sure that the state Y is somehow
4620 // a precursor to state Y'.
4621 //
4622 //
4623 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
4624 // of each MergeMemNode array are exactly the numerical alias indexes, including
4625 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
4626 // Compile::alias_type (and kin) produce and manage these indexes.
4627 //
4628 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
4629 // (Note that this provides quick access to the top node inside MergeMem methods,
4630 // without the need to reach out via TLS to Compile::current.)
4631 //
4632 // As a consequence of what was just described, a MergeMem that represents a full
4633 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
4634 // containing all alias categories.
4635 //
4636 // MergeMem nodes never (?) have control inputs, so in(0) is null.
4637 //
4638 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
4639 // a memory state for the alias type <N>, or else the top node, meaning that
4640 // there is no particular input for that alias type. Note that the length of
4641 // a MergeMem is variable, and may be extended at any time to accommodate new
4642 // memory states at larger alias indexes. When merges grow, they are of course
4643 // filled with "top" in the unused in() positions.
4644 //
4645 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
4646 // (Top was chosen because it works smoothly with passes like GCM.)
4647 //
4648 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
4649 // the type of random VM bits like TLS references.) Since it is always the
4650 // first non-Bot memory slice, some low-level loops use it to initialize an
4651 // index variable: for (i = AliasIdxRaw; i < req(); i++).
4652 //
4653 //
4654 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
4655 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
4656 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
4657 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
4658 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
4659 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
4660 //
4661 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
4662 // really that different from the other memory inputs. An abbreviation called
4663 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
4664 //
4665 //
4666 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
4667 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
4668 // that "emerges though" the base memory will be marked as excluding the alias types
4669 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
4670 //
4671 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
4672 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
4673 //
4674 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
4675 // (It is currently unimplemented.) As you can see, the resulting merge is
4676 // actually a disjoint union of memory states, rather than an overlay.
4677 //
4678
4679 //------------------------------MergeMemNode-----------------------------------
4680 Node* MergeMemNode::make_empty_memory() {
4681 Node* empty_memory = (Node*) Compile::current()->top();
4682 assert(empty_memory->is_top(), "correct sentinel identity");
4683 return empty_memory;
4684 }
4685
4686 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
4687 init_class_id(Class_MergeMem);
4688 // all inputs are nullified in Node::Node(int)
4689 // set_input(0, nullptr); // no control input
4690
4691 // Initialize the edges uniformly to top, for starters.
4692 Node* empty_mem = make_empty_memory();
4693 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
4694 init_req(i,empty_mem);
4695 }
4696 assert(empty_memory() == empty_mem, "");
4697
4698 if( new_base != nullptr && new_base->is_MergeMem() ) {
4699 MergeMemNode* mdef = new_base->as_MergeMem();
4700 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
4701 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
4702 mms.set_memory(mms.memory2());
4703 }
4704 assert(base_memory() == mdef->base_memory(), "");
4705 } else {
4706 set_base_memory(new_base);
4707 }
4708 }
4709
4710 // Make a new, untransformed MergeMem with the same base as 'mem'.
4711 // If mem is itself a MergeMem, populate the result with the same edges.
4712 MergeMemNode* MergeMemNode::make(Node* mem) {
4713 return new MergeMemNode(mem);
4714 }
4715
4716 //------------------------------cmp--------------------------------------------
4717 uint MergeMemNode::hash() const { return NO_HASH; }
4718 bool MergeMemNode::cmp( const Node &n ) const {
4719 return (&n == this); // Always fail except on self
4720 }
4721
4722 //------------------------------Identity---------------------------------------
4723 Node* MergeMemNode::Identity(PhaseGVN* phase) {
4724 // Identity if this merge point does not record any interesting memory
4725 // disambiguations.
4726 Node* base_mem = base_memory();
4727 Node* empty_mem = empty_memory();
4728 if (base_mem != empty_mem) { // Memory path is not dead?
4729 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4730 Node* mem = in(i);
4731 if (mem != empty_mem && mem != base_mem) {
4732 return this; // Many memory splits; no change
4733 }
4734 }
4735 }
4736 return base_mem; // No memory splits; ID on the one true input
4737 }
4738
4739 //------------------------------Ideal------------------------------------------
4740 // This method is invoked recursively on chains of MergeMem nodes
4741 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4742 // Remove chain'd MergeMems
4743 //
4744 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
4745 // relative to the "in(Bot)". Since we are patching both at the same time,
4746 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
4747 // but rewrite each "in(i)" relative to the new "in(Bot)".
4748 Node *progress = nullptr;
4749
4750
4751 Node* old_base = base_memory();
4752 Node* empty_mem = empty_memory();
4753 if (old_base == empty_mem)
4754 return nullptr; // Dead memory path.
4755
4756 MergeMemNode* old_mbase;
4757 if (old_base != nullptr && old_base->is_MergeMem())
4758 old_mbase = old_base->as_MergeMem();
4759 else
4760 old_mbase = nullptr;
4761 Node* new_base = old_base;
4762
4763 // simplify stacked MergeMems in base memory
4764 if (old_mbase) new_base = old_mbase->base_memory();
4765
4766 // the base memory might contribute new slices beyond my req()
4767 if (old_mbase) grow_to_match(old_mbase);
4768
4769 // Note: We do not call verify_sparse on entry, because inputs
4770 // can normalize to the base_memory via subsume_node or similar
4771 // mechanisms. This method repairs that damage.
4772
4773 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
4774
4775 // Look at each slice.
4776 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4777 Node* old_in = in(i);
4778 // calculate the old memory value
4779 Node* old_mem = old_in;
4780 if (old_mem == empty_mem) old_mem = old_base;
4781 assert(old_mem == memory_at(i), "");
4782
4783 // maybe update (reslice) the old memory value
4784
4785 // simplify stacked MergeMems
4786 Node* new_mem = old_mem;
4787 MergeMemNode* old_mmem;
4788 if (old_mem != nullptr && old_mem->is_MergeMem())
4789 old_mmem = old_mem->as_MergeMem();
4790 else
4791 old_mmem = nullptr;
4792 if (old_mmem == this) {
4793 // This can happen if loops break up and safepoints disappear.
4794 // A merge of BotPtr (default) with a RawPtr memory derived from a
4795 // safepoint can be rewritten to a merge of the same BotPtr with
4796 // the BotPtr phi coming into the loop. If that phi disappears
4797 // also, we can end up with a self-loop of the mergemem.
4798 // In general, if loops degenerate and memory effects disappear,
4799 // a mergemem can be left looking at itself. This simply means
4800 // that the mergemem's default should be used, since there is
4801 // no longer any apparent effect on this slice.
4802 // Note: If a memory slice is a MergeMem cycle, it is unreachable
4803 // from start. Update the input to TOP.
4804 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
4805 }
4806 else if (old_mmem != nullptr) {
4807 new_mem = old_mmem->memory_at(i);
4808 }
4809 // else preceding memory was not a MergeMem
4810
4811 // maybe store down a new value
4812 Node* new_in = new_mem;
4813 if (new_in == new_base) new_in = empty_mem;
4814
4815 if (new_in != old_in) {
4816 // Warning: Do not combine this "if" with the previous "if"
4817 // A memory slice might have be be rewritten even if it is semantically
4818 // unchanged, if the base_memory value has changed.
4819 set_req_X(i, new_in, phase);
4820 progress = this; // Report progress
4821 }
4822 }
4823
4824 if (new_base != old_base) {
4825 set_req_X(Compile::AliasIdxBot, new_base, phase);
4826 // Don't use set_base_memory(new_base), because we need to update du.
4827 assert(base_memory() == new_base, "");
4828 progress = this;
4829 }
4830
4831 if( base_memory() == this ) {
4832 // a self cycle indicates this memory path is dead
4833 set_req(Compile::AliasIdxBot, empty_mem);
4834 }
4835
4836 // Resolve external cycles by calling Ideal on a MergeMem base_memory
4837 // Recursion must occur after the self cycle check above
4838 if( base_memory()->is_MergeMem() ) {
4839 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
4840 Node *m = phase->transform(new_mbase); // Rollup any cycles
4841 if( m != nullptr &&
4842 (m->is_top() ||
4843 (m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem)) ) {
4844 // propagate rollup of dead cycle to self
4845 set_req(Compile::AliasIdxBot, empty_mem);
4846 }
4847 }
4848
4849 if( base_memory() == empty_mem ) {
4850 progress = this;
4851 // Cut inputs during Parse phase only.
4852 // During Optimize phase a dead MergeMem node will be subsumed by Top.
4853 if( !can_reshape ) {
4854 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4855 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
4856 }
4857 }
4858 }
4859
4860 if( !progress && base_memory()->is_Phi() && can_reshape ) {
4861 // Check if PhiNode::Ideal's "Split phis through memory merges"
4862 // transform should be attempted. Look for this->phi->this cycle.
4863 uint merge_width = req();
4864 if (merge_width > Compile::AliasIdxRaw) {
4865 PhiNode* phi = base_memory()->as_Phi();
4866 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
4867 if (phi->in(i) == this) {
4868 phase->is_IterGVN()->_worklist.push(phi);
4869 break;
4870 }
4871 }
4872 }
4873 }
4874
4875 assert(progress || verify_sparse(), "please, no dups of base");
4876 return progress;
4877 }
4878
4879 //-------------------------set_base_memory-------------------------------------
4880 void MergeMemNode::set_base_memory(Node *new_base) {
4881 Node* empty_mem = empty_memory();
4882 set_req(Compile::AliasIdxBot, new_base);
4883 assert(memory_at(req()) == new_base, "must set default memory");
4884 // Clear out other occurrences of new_base:
4885 if (new_base != empty_mem) {
4886 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4887 if (in(i) == new_base) set_req(i, empty_mem);
4888 }
4889 }
4890 }
4891
4892 //------------------------------out_RegMask------------------------------------
4893 const RegMask &MergeMemNode::out_RegMask() const {
4894 return RegMask::Empty;
4895 }
4896
4897 //------------------------------dump_spec--------------------------------------
4898 #ifndef PRODUCT
4899 void MergeMemNode::dump_spec(outputStream *st) const {
4900 st->print(" {");
4901 Node* base_mem = base_memory();
4902 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
4903 Node* mem = (in(i) != nullptr) ? memory_at(i) : base_mem;
4904 if (mem == base_mem) { st->print(" -"); continue; }
4905 st->print( " N%d:", mem->_idx );
4906 Compile::current()->get_adr_type(i)->dump_on(st);
4907 }
4908 st->print(" }");
4909 }
4910 #endif // !PRODUCT
4911
4912
4913 #ifdef ASSERT
4914 static bool might_be_same(Node* a, Node* b) {
4915 if (a == b) return true;
4916 if (!(a->is_Phi() || b->is_Phi())) return false;
4917 // phis shift around during optimization
4918 return true; // pretty stupid...
4919 }
4920
4921 // verify a narrow slice (either incoming or outgoing)
4922 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
4923 if (!VerifyAliases) return; // don't bother to verify unless requested
4924 if (VMError::is_error_reported()) return; // muzzle asserts when debugging an error
4925 if (Node::in_dump()) return; // muzzle asserts when printing
4926 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
4927 assert(n != nullptr, "");
4928 // Elide intervening MergeMem's
4929 while (n->is_MergeMem()) {
4930 n = n->as_MergeMem()->memory_at(alias_idx);
4931 }
4932 Compile* C = Compile::current();
4933 const TypePtr* n_adr_type = n->adr_type();
4934 if (n == m->empty_memory()) {
4935 // Implicit copy of base_memory()
4936 } else if (n_adr_type != TypePtr::BOTTOM) {
4937 assert(n_adr_type != nullptr, "new memory must have a well-defined adr_type");
4938 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
4939 } else {
4940 // A few places like make_runtime_call "know" that VM calls are narrow,
4941 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
4942 bool expected_wide_mem = false;
4943 if (n == m->base_memory()) {
4944 expected_wide_mem = true;
4945 } else if (alias_idx == Compile::AliasIdxRaw ||
4946 n == m->memory_at(Compile::AliasIdxRaw)) {
4947 expected_wide_mem = true;
4948 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
4949 // memory can "leak through" calls on channels that
4950 // are write-once. Allow this also.
4951 expected_wide_mem = true;
4952 }
4953 assert(expected_wide_mem, "expected narrow slice replacement");
4954 }
4955 }
4956 #else // !ASSERT
4957 #define verify_memory_slice(m,i,n) (void)(0) // PRODUCT version is no-op
4958 #endif
4959
4960
4961 //-----------------------------memory_at---------------------------------------
4962 Node* MergeMemNode::memory_at(uint alias_idx) const {
4963 assert(alias_idx >= Compile::AliasIdxRaw ||
4964 alias_idx == Compile::AliasIdxBot && !Compile::current()->do_aliasing(),
4965 "must avoid base_memory and AliasIdxTop");
4966
4967 // Otherwise, it is a narrow slice.
4968 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
4969 if (is_empty_memory(n)) {
4970 // the array is sparse; empty slots are the "top" node
4971 n = base_memory();
4972 assert(Node::in_dump()
4973 || n == nullptr || n->bottom_type() == Type::TOP
4974 || n->adr_type() == nullptr // address is TOP
4975 || n->adr_type() == TypePtr::BOTTOM
4976 || n->adr_type() == TypeRawPtr::BOTTOM
4977 || !Compile::current()->do_aliasing(),
4978 "must be a wide memory");
4979 // do_aliasing == false if we are organizing the memory states manually.
4980 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
4981 } else {
4982 // make sure the stored slice is sane
4983 #ifdef ASSERT
4984 if (VMError::is_error_reported() || Node::in_dump()) {
4985 } else if (might_be_same(n, base_memory())) {
4986 // Give it a pass: It is a mostly harmless repetition of the base.
4987 // This can arise normally from node subsumption during optimization.
4988 } else {
4989 verify_memory_slice(this, alias_idx, n);
4990 }
4991 #endif
4992 }
4993 return n;
4994 }
4995
4996 //---------------------------set_memory_at-------------------------------------
4997 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
4998 verify_memory_slice(this, alias_idx, n);
4999 Node* empty_mem = empty_memory();
5000 if (n == base_memory()) n = empty_mem; // collapse default
5001 uint need_req = alias_idx+1;
5002 if (req() < need_req) {
5003 if (n == empty_mem) return; // already the default, so do not grow me
5004 // grow the sparse array
5005 do {
5006 add_req(empty_mem);
5007 } while (req() < need_req);
5008 }
5009 set_req( alias_idx, n );
5010 }
5011
5012
5013
5014 //--------------------------iteration_setup------------------------------------
5015 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
5016 if (other != nullptr) {
5017 grow_to_match(other);
5018 // invariant: the finite support of mm2 is within mm->req()
5019 #ifdef ASSERT
5020 for (uint i = req(); i < other->req(); i++) {
5021 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
5022 }
5023 #endif
5024 }
5025 // Replace spurious copies of base_memory by top.
5026 Node* base_mem = base_memory();
5027 if (base_mem != nullptr && !base_mem->is_top()) {
5028 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
5029 if (in(i) == base_mem)
5030 set_req(i, empty_memory());
5031 }
5032 }
5033 }
5034
5035 //---------------------------grow_to_match-------------------------------------
5036 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
5037 Node* empty_mem = empty_memory();
5038 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
5039 // look for the finite support of the other memory
5040 for (uint i = other->req(); --i >= req(); ) {
5041 if (other->in(i) != empty_mem) {
5042 uint new_len = i+1;
5043 while (req() < new_len) add_req(empty_mem);
5044 break;
5045 }
5046 }
5047 }
5048
5049 //---------------------------verify_sparse-------------------------------------
5050 #ifndef PRODUCT
5051 bool MergeMemNode::verify_sparse() const {
5052 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
5053 Node* base_mem = base_memory();
5054 // The following can happen in degenerate cases, since empty==top.
5055 if (is_empty_memory(base_mem)) return true;
5056 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5057 assert(in(i) != nullptr, "sane slice");
5058 if (in(i) == base_mem) return false; // should have been the sentinel value!
5059 }
5060 return true;
5061 }
5062
5063 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
5064 Node* n;
5065 n = mm->in(idx);
5066 if (mem == n) return true; // might be empty_memory()
5067 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
5068 if (mem == n) return true;
5069 return false;
5070 }
5071 #endif // !PRODUCT