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(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(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));
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);
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),
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 { return !Type::cmp( _type, ((LoadNode&)n)._type ); }
850 const Type *LoadNode::bottom_type() const { return _type; }
851 uint LoadNode::ideal_reg() const {
852 return _type->ideal_reg();
853 }
854
855 #ifndef PRODUCT
856 void LoadNode::dump_spec(outputStream *st) const {
857 MemNode::dump_spec(st);
858 if( !Verbose && !WizardMode ) {
859 // standard dump does this in Verbose and WizardMode
860 st->print(" #"); _type->dump_on(st);
861 }
862 if (!depends_only_on_test()) {
863 st->print(" (does not depend only on test, ");
864 if (control_dependency() == UnknownControl) {
865 st->print("unknown control");
866 } else if (control_dependency() == Pinned) {
867 st->print("pinned");
868 } else if (adr_type() == TypeRawPtr::BOTTOM) {
869 st->print("raw access");
870 } else {
871 st->print("unknown reason");
872 }
873 st->print(")");
874 }
875 }
876 #endif
877
878 #ifdef ASSERT
879 //----------------------------is_immutable_value-------------------------------
880 // Helper function to allow a raw load without control edge for some cases
881 bool LoadNode::is_immutable_value(Node* adr) {
882 if (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() &&
883 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal) {
884
885 jlong offset = adr->in(AddPNode::Offset)->find_intptr_t_con(-1);
886 int offsets[] = {
887 in_bytes(JavaThread::osthread_offset()),
888 in_bytes(JavaThread::threadObj_offset()),
889 in_bytes(JavaThread::vthread_offset()),
890 in_bytes(JavaThread::scopedValueCache_offset()),
891 };
892
893 for (size_t i = 0; i < sizeof offsets / sizeof offsets[0]; i++) {
894 if (offset == offsets[i]) {
895 return true;
896 }
897 }
898 }
899
900 return false;
901 }
902 #endif
903
904 //----------------------------LoadNode::make-----------------------------------
905 // Polymorphic factory method:
906 Node* LoadNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, BasicType bt, MemOrd mo,
907 ControlDependency control_dependency, bool require_atomic_access, bool unaligned, bool mismatched, bool unsafe, uint8_t barrier_data) {
908 Compile* C = gvn.C;
909
910 // sanity check the alias category against the created node type
911 assert(!(adr_type->isa_oopptr() &&
912 adr_type->offset() == oopDesc::klass_offset_in_bytes()),
913 "use LoadKlassNode instead");
914 assert(!(adr_type->isa_aryptr() &&
915 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
916 "use LoadRangeNode instead");
917 // Check control edge of raw loads
918 assert( ctl != nullptr || C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
919 // oop will be recorded in oop map if load crosses safepoint
920 rt->isa_oopptr() || is_immutable_value(adr),
921 "raw memory operations should have control edge");
922 LoadNode* load = nullptr;
923 switch (bt) {
924 case T_BOOLEAN: load = new LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
925 case T_BYTE: load = new LoadBNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
926 case T_INT: load = new LoadINode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
927 case T_CHAR: load = new LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
928 case T_SHORT: load = new LoadSNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
929 case T_LONG: load = new LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency, require_atomic_access); break;
930 case T_FLOAT: load = new LoadFNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); break;
931 case T_DOUBLE: load = new LoadDNode (ctl, mem, adr, adr_type, rt, mo, control_dependency, require_atomic_access); break;
932 case T_ADDRESS: load = new LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency); break;
933 case T_OBJECT:
934 #ifdef _LP64
935 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
936 load = new LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo, control_dependency);
937 } else
938 #endif
939 {
940 assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop");
941 load = new LoadPNode(ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency);
942 }
943 break;
944 default:
945 ShouldNotReachHere();
946 break;
947 }
948 assert(load != nullptr, "LoadNode should have been created");
949 if (unaligned) {
950 load->set_unaligned_access();
951 }
952 if (mismatched) {
953 load->set_mismatched_access();
954 }
955 if (unsafe) {
956 load->set_unsafe_access();
957 }
958 load->set_barrier_data(barrier_data);
959 if (load->Opcode() == Op_LoadN) {
960 Node* ld = gvn.transform(load);
961 return new DecodeNNode(ld, ld->bottom_type()->make_ptr());
962 }
963
964 return load;
965 }
966
967 //------------------------------hash-------------------------------------------
968 uint LoadNode::hash() const {
969 // unroll addition of interesting fields
970 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
971 }
972
973 static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) {
974 if ((atp != nullptr) && (atp->index() >= Compile::AliasIdxRaw)) {
975 bool non_volatile = (atp->field() != nullptr) && !atp->field()->is_volatile();
976 bool is_stable_ary = FoldStableValues &&
977 (tp != nullptr) && (tp->isa_aryptr() != nullptr) &&
978 tp->isa_aryptr()->is_stable();
979
980 return (eliminate_boxing && non_volatile) || is_stable_ary;
981 }
982
983 return false;
984 }
985
986 // Is the value loaded previously stored by an arraycopy? If so return
987 // a load node that reads from the source array so we may be able to
988 // optimize out the ArrayCopy node later.
989 Node* LoadNode::can_see_arraycopy_value(Node* st, PhaseGVN* phase) const {
990 Node* ld_adr = in(MemNode::Address);
991 intptr_t ld_off = 0;
992 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
993 Node* ac = find_previous_arraycopy(phase, ld_alloc, st, true);
994 if (ac != nullptr) {
995 assert(ac->is_ArrayCopy(), "what kind of node can this be?");
996
997 Node* mem = ac->in(TypeFunc::Memory);
998 Node* ctl = ac->in(0);
999 Node* src = ac->in(ArrayCopyNode::Src);
1000
1001 if (!ac->as_ArrayCopy()->is_clonebasic() && !phase->type(src)->isa_aryptr()) {
1002 return nullptr;
1003 }
1004
1005 LoadNode* ld = clone()->as_Load();
1006 Node* addp = in(MemNode::Address)->clone();
1007 if (ac->as_ArrayCopy()->is_clonebasic()) {
1008 assert(ld_alloc != nullptr, "need an alloc");
1009 assert(addp->is_AddP(), "address must be addp");
1010 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1011 assert(bs->step_over_gc_barrier(addp->in(AddPNode::Base)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)), "strange pattern");
1012 assert(bs->step_over_gc_barrier(addp->in(AddPNode::Address)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)), "strange pattern");
1013 addp->set_req(AddPNode::Base, src);
1014 addp->set_req(AddPNode::Address, src);
1015 } else {
1016 assert(ac->as_ArrayCopy()->is_arraycopy_validated() ||
1017 ac->as_ArrayCopy()->is_copyof_validated() ||
1018 ac->as_ArrayCopy()->is_copyofrange_validated(), "only supported cases");
1019 assert(addp->in(AddPNode::Base) == addp->in(AddPNode::Address), "should be");
1020 addp->set_req(AddPNode::Base, src);
1021 addp->set_req(AddPNode::Address, src);
1022
1023 const TypeAryPtr* ary_t = phase->type(in(MemNode::Address))->isa_aryptr();
1024 BasicType ary_elem = ary_t->isa_aryptr()->elem()->array_element_basic_type();
1025 if (is_reference_type(ary_elem, true)) ary_elem = T_OBJECT;
1026
1027 uint header = arrayOopDesc::base_offset_in_bytes(ary_elem);
1028 uint shift = exact_log2(type2aelembytes(ary_elem));
1029
1030 Node* diff = phase->transform(new SubINode(ac->in(ArrayCopyNode::SrcPos), ac->in(ArrayCopyNode::DestPos)));
1031 #ifdef _LP64
1032 diff = phase->transform(new ConvI2LNode(diff));
1033 #endif
1034 diff = phase->transform(new LShiftXNode(diff, phase->intcon(shift)));
1035
1036 Node* offset = phase->transform(new AddXNode(addp->in(AddPNode::Offset), diff));
1037 addp->set_req(AddPNode::Offset, offset);
1038 }
1039 addp = phase->transform(addp);
1040 #ifdef ASSERT
1041 const TypePtr* adr_type = phase->type(addp)->is_ptr();
1042 ld->_adr_type = adr_type;
1043 #endif
1044 ld->set_req(MemNode::Address, addp);
1045 ld->set_req(0, ctl);
1046 ld->set_req(MemNode::Memory, mem);
1047 // load depends on the tests that validate the arraycopy
1048 ld->_control_dependency = UnknownControl;
1049 return ld;
1050 }
1051 return nullptr;
1052 }
1053
1054
1055 //---------------------------can_see_stored_value------------------------------
1056 // This routine exists to make sure this set of tests is done the same
1057 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
1058 // will change the graph shape in a way which makes memory alive twice at the
1059 // same time (uses the Oracle model of aliasing), then some
1060 // LoadXNode::Identity will fold things back to the equivalence-class model
1061 // of aliasing.
1062 Node* MemNode::can_see_stored_value(Node* st, PhaseValues* phase) const {
1063 Node* ld_adr = in(MemNode::Address);
1064 intptr_t ld_off = 0;
1065 Node* ld_base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ld_off);
1066 Node* ld_alloc = AllocateNode::Ideal_allocation(ld_base);
1067 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
1068 Compile::AliasType* atp = (tp != nullptr) ? phase->C->alias_type(tp) : nullptr;
1069 // This is more general than load from boxing objects.
1070 if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) {
1071 uint alias_idx = atp->index();
1072 Node* result = nullptr;
1073 Node* current = st;
1074 // Skip through chains of MemBarNodes checking the MergeMems for
1075 // new states for the slice of this load. Stop once any other
1076 // kind of node is encountered. Loads from final memory can skip
1077 // through any kind of MemBar but normal loads shouldn't skip
1078 // through MemBarAcquire since the could allow them to move out of
1079 // a synchronized region. It is not safe to step over MemBarCPUOrder,
1080 // because alias info above them may be inaccurate (e.g., due to
1081 // mixed/mismatched unsafe accesses).
1082 bool is_final_mem = !atp->is_rewritable();
1083 while (current->is_Proj()) {
1084 int opc = current->in(0)->Opcode();
1085 if ((is_final_mem && (opc == Op_MemBarAcquire ||
1086 opc == Op_MemBarAcquireLock ||
1087 opc == Op_LoadFence)) ||
1088 opc == Op_MemBarRelease ||
1089 opc == Op_StoreFence ||
1090 opc == Op_MemBarReleaseLock ||
1091 opc == Op_MemBarStoreStore ||
1092 opc == Op_StoreStoreFence) {
1093 Node* mem = current->in(0)->in(TypeFunc::Memory);
1094 if (mem->is_MergeMem()) {
1095 MergeMemNode* merge = mem->as_MergeMem();
1096 Node* new_st = merge->memory_at(alias_idx);
1097 if (new_st == merge->base_memory()) {
1098 // Keep searching
1099 current = new_st;
1100 continue;
1101 }
1102 // Save the new memory state for the slice and fall through
1103 // to exit.
1104 result = new_st;
1105 }
1106 }
1107 break;
1108 }
1109 if (result != nullptr) {
1110 st = result;
1111 }
1112 }
1113
1114 // Loop around twice in the case Load -> Initialize -> Store.
1115 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
1116 for (int trip = 0; trip <= 1; trip++) {
1117
1118 if (st->is_Store()) {
1119 Node* st_adr = st->in(MemNode::Address);
1120 if (st_adr != ld_adr) {
1121 // Try harder before giving up. Unify base pointers with casts (e.g., raw/non-raw pointers).
1122 intptr_t st_off = 0;
1123 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_off);
1124 if (ld_base == nullptr) return nullptr;
1125 if (st_base == nullptr) return nullptr;
1126 if (!ld_base->eqv_uncast(st_base, /*keep_deps=*/true)) return nullptr;
1127 if (ld_off != st_off) return nullptr;
1128 if (ld_off == Type::OffsetBot) return nullptr;
1129 // Same base, same offset.
1130 // Possible improvement for arrays: check index value instead of absolute offset.
1131
1132 // At this point we have proven something like this setup:
1133 // B = << base >>
1134 // L = LoadQ(AddP(Check/CastPP(B), #Off))
1135 // S = StoreQ(AddP( B , #Off), V)
1136 // (Actually, we haven't yet proven the Q's are the same.)
1137 // In other words, we are loading from a casted version of
1138 // the same pointer-and-offset that we stored to.
1139 // Casted version may carry a dependency and it is respected.
1140 // Thus, we are able to replace L by V.
1141 }
1142 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
1143 if (store_Opcode() != st->Opcode()) {
1144 return nullptr;
1145 }
1146 // LoadVector/StoreVector needs additional check to ensure the types match.
1147 if (st->is_StoreVector()) {
1148 const TypeVect* in_vt = st->as_StoreVector()->vect_type();
1149 const TypeVect* out_vt = as_LoadVector()->vect_type();
1150 if (in_vt != out_vt) {
1151 return nullptr;
1152 }
1153 }
1154 return st->in(MemNode::ValueIn);
1155 }
1156
1157 // A load from a freshly-created object always returns zero.
1158 // (This can happen after LoadNode::Ideal resets the load's memory input
1159 // to find_captured_store, which returned InitializeNode::zero_memory.)
1160 if (st->is_Proj() && st->in(0)->is_Allocate() &&
1161 (st->in(0) == ld_alloc) &&
1162 (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) {
1163 // return a zero value for the load's basic type
1164 // (This is one of the few places where a generic PhaseTransform
1165 // can create new nodes. Think of it as lazily manifesting
1166 // virtually pre-existing constants.)
1167 if (memory_type() != T_VOID) {
1168 if (ReduceBulkZeroing || find_array_copy_clone(ld_alloc, in(MemNode::Memory)) == nullptr) {
1169 // If ReduceBulkZeroing is disabled, we need to check if the allocation does not belong to an
1170 // ArrayCopyNode clone. If it does, then we cannot assume zero since the initialization is done
1171 // by the ArrayCopyNode.
1172 return phase->zerocon(memory_type());
1173 }
1174 } else {
1175 // TODO: materialize all-zero vector constant
1176 assert(!isa_Load() || as_Load()->type()->isa_vect(), "");
1177 }
1178 }
1179
1180 // A load from an initialization barrier can match a captured store.
1181 if (st->is_Proj() && st->in(0)->is_Initialize()) {
1182 InitializeNode* init = st->in(0)->as_Initialize();
1183 AllocateNode* alloc = init->allocation();
1184 if ((alloc != nullptr) && (alloc == ld_alloc)) {
1185 // examine a captured store value
1186 st = init->find_captured_store(ld_off, memory_size(), phase);
1187 if (st != nullptr) {
1188 continue; // take one more trip around
1189 }
1190 }
1191 }
1192
1193 // Load boxed value from result of valueOf() call is input parameter.
1194 if (this->is_Load() && ld_adr->is_AddP() &&
1195 (tp != nullptr) && tp->is_ptr_to_boxed_value()) {
1196 intptr_t ignore = 0;
1197 Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore);
1198 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1199 base = bs->step_over_gc_barrier(base);
1200 if (base != nullptr && base->is_Proj() &&
1201 base->as_Proj()->_con == TypeFunc::Parms &&
1202 base->in(0)->is_CallStaticJava() &&
1203 base->in(0)->as_CallStaticJava()->is_boxing_method()) {
1204 return base->in(0)->in(TypeFunc::Parms);
1205 }
1206 }
1207
1208 break;
1209 }
1210
1211 return nullptr;
1212 }
1213
1214 //----------------------is_instance_field_load_with_local_phi------------------
1215 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
1216 if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl &&
1217 in(Address)->is_AddP() ) {
1218 const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr();
1219 // Only instances and boxed values.
1220 if( t_oop != nullptr &&
1221 (t_oop->is_ptr_to_boxed_value() ||
1222 t_oop->is_known_instance_field()) &&
1223 t_oop->offset() != Type::OffsetBot &&
1224 t_oop->offset() != Type::OffsetTop) {
1225 return true;
1226 }
1227 }
1228 return false;
1229 }
1230
1231 //------------------------------Identity---------------------------------------
1232 // Loads are identity if previous store is to same address
1233 Node* LoadNode::Identity(PhaseGVN* phase) {
1234 // If the previous store-maker is the right kind of Store, and the store is
1235 // to the same address, then we are equal to the value stored.
1236 Node* mem = in(Memory);
1237 Node* value = can_see_stored_value(mem, phase);
1238 if( value ) {
1239 // byte, short & char stores truncate naturally.
1240 // A load has to load the truncated value which requires
1241 // some sort of masking operation and that requires an
1242 // Ideal call instead of an Identity call.
1243 if (memory_size() < BytesPerInt) {
1244 // If the input to the store does not fit with the load's result type,
1245 // it must be truncated via an Ideal call.
1246 if (!phase->type(value)->higher_equal(phase->type(this)))
1247 return this;
1248 }
1249 // (This works even when value is a Con, but LoadNode::Value
1250 // usually runs first, producing the singleton type of the Con.)
1251 if (!has_pinned_control_dependency() || value->is_Con()) {
1252 return value;
1253 } else {
1254 return this;
1255 }
1256 }
1257
1258 if (has_pinned_control_dependency()) {
1259 return this;
1260 }
1261 // Search for an existing data phi which was generated before for the same
1262 // instance's field to avoid infinite generation of phis in a loop.
1263 Node *region = mem->in(0);
1264 if (is_instance_field_load_with_local_phi(region)) {
1265 const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr();
1266 int this_index = phase->C->get_alias_index(addr_t);
1267 int this_offset = addr_t->offset();
1268 int this_iid = addr_t->instance_id();
1269 if (!addr_t->is_known_instance() &&
1270 addr_t->is_ptr_to_boxed_value()) {
1271 // Use _idx of address base (could be Phi node) for boxed values.
1272 intptr_t ignore = 0;
1273 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1274 if (base == nullptr) {
1275 return this;
1276 }
1277 this_iid = base->_idx;
1278 }
1279 const Type* this_type = bottom_type();
1280 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1281 Node* phi = region->fast_out(i);
1282 if (phi->is_Phi() && phi != mem &&
1283 phi->as_Phi()->is_same_inst_field(this_type, (int)mem->_idx, this_iid, this_index, this_offset)) {
1284 return phi;
1285 }
1286 }
1287 }
1288
1289 return this;
1290 }
1291
1292 // Construct an equivalent unsigned load.
1293 Node* LoadNode::convert_to_unsigned_load(PhaseGVN& gvn) {
1294 BasicType bt = T_ILLEGAL;
1295 const Type* rt = nullptr;
1296 switch (Opcode()) {
1297 case Op_LoadUB: return this;
1298 case Op_LoadUS: return this;
1299 case Op_LoadB: bt = T_BOOLEAN; rt = TypeInt::UBYTE; break;
1300 case Op_LoadS: bt = T_CHAR; rt = TypeInt::CHAR; break;
1301 default:
1302 assert(false, "no unsigned variant: %s", Name());
1303 return nullptr;
1304 }
1305 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1306 raw_adr_type(), rt, bt, _mo, _control_dependency,
1307 false /*require_atomic_access*/, is_unaligned_access(), is_mismatched_access());
1308 }
1309
1310 // Construct an equivalent signed load.
1311 Node* LoadNode::convert_to_signed_load(PhaseGVN& gvn) {
1312 BasicType bt = T_ILLEGAL;
1313 const Type* rt = nullptr;
1314 switch (Opcode()) {
1315 case Op_LoadUB: bt = T_BYTE; rt = TypeInt::BYTE; break;
1316 case Op_LoadUS: bt = T_SHORT; rt = TypeInt::SHORT; break;
1317 case Op_LoadB: // fall through
1318 case Op_LoadS: // fall through
1319 case Op_LoadI: // fall through
1320 case Op_LoadL: return this;
1321 default:
1322 assert(false, "no signed variant: %s", Name());
1323 return nullptr;
1324 }
1325 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1326 raw_adr_type(), rt, bt, _mo, _control_dependency,
1327 false /*require_atomic_access*/, is_unaligned_access(), is_mismatched_access());
1328 }
1329
1330 bool LoadNode::has_reinterpret_variant(const Type* rt) {
1331 BasicType bt = rt->basic_type();
1332 switch (Opcode()) {
1333 case Op_LoadI: return (bt == T_FLOAT);
1334 case Op_LoadL: return (bt == T_DOUBLE);
1335 case Op_LoadF: return (bt == T_INT);
1336 case Op_LoadD: return (bt == T_LONG);
1337
1338 default: return false;
1339 }
1340 }
1341
1342 Node* LoadNode::convert_to_reinterpret_load(PhaseGVN& gvn, const Type* rt) {
1343 BasicType bt = rt->basic_type();
1344 assert(has_reinterpret_variant(rt), "no reinterpret variant: %s %s", Name(), type2name(bt));
1345 bool is_mismatched = is_mismatched_access();
1346 const TypeRawPtr* raw_type = gvn.type(in(MemNode::Memory))->isa_rawptr();
1347 if (raw_type == nullptr) {
1348 is_mismatched = true; // conservatively match all non-raw accesses as mismatched
1349 }
1350 const int op = Opcode();
1351 bool require_atomic_access = (op == Op_LoadL && ((LoadLNode*)this)->require_atomic_access()) ||
1352 (op == Op_LoadD && ((LoadDNode*)this)->require_atomic_access());
1353 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1354 raw_adr_type(), rt, bt, _mo, _control_dependency,
1355 require_atomic_access, is_unaligned_access(), is_mismatched);
1356 }
1357
1358 bool StoreNode::has_reinterpret_variant(const Type* vt) {
1359 BasicType bt = vt->basic_type();
1360 switch (Opcode()) {
1361 case Op_StoreI: return (bt == T_FLOAT);
1362 case Op_StoreL: return (bt == T_DOUBLE);
1363 case Op_StoreF: return (bt == T_INT);
1364 case Op_StoreD: return (bt == T_LONG);
1365
1366 default: return false;
1367 }
1368 }
1369
1370 Node* StoreNode::convert_to_reinterpret_store(PhaseGVN& gvn, Node* val, const Type* vt) {
1371 BasicType bt = vt->basic_type();
1372 assert(has_reinterpret_variant(vt), "no reinterpret variant: %s %s", Name(), type2name(bt));
1373 const int op = Opcode();
1374 bool require_atomic_access = (op == Op_StoreL && ((StoreLNode*)this)->require_atomic_access()) ||
1375 (op == Op_StoreD && ((StoreDNode*)this)->require_atomic_access());
1376 StoreNode* st = StoreNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1377 raw_adr_type(), val, bt, _mo, require_atomic_access);
1378
1379 bool is_mismatched = is_mismatched_access();
1380 const TypeRawPtr* raw_type = gvn.type(in(MemNode::Memory))->isa_rawptr();
1381 if (raw_type == nullptr) {
1382 is_mismatched = true; // conservatively match all non-raw accesses as mismatched
1383 }
1384 if (is_mismatched) {
1385 st->set_mismatched_access();
1386 }
1387 return st;
1388 }
1389
1390 // We're loading from an object which has autobox behaviour.
1391 // If this object is result of a valueOf call we'll have a phi
1392 // merging a newly allocated object and a load from the cache.
1393 // We want to replace this load with the original incoming
1394 // argument to the valueOf call.
1395 Node* LoadNode::eliminate_autobox(PhaseIterGVN* igvn) {
1396 assert(igvn->C->eliminate_boxing(), "sanity");
1397 intptr_t ignore = 0;
1398 Node* base = AddPNode::Ideal_base_and_offset(in(Address), igvn, ignore);
1399 if ((base == nullptr) || base->is_Phi()) {
1400 // Push the loads from the phi that comes from valueOf up
1401 // through it to allow elimination of the loads and the recovery
1402 // of the original value. It is done in split_through_phi().
1403 return nullptr;
1404 } else if (base->is_Load() ||
1405 (base->is_DecodeN() && base->in(1)->is_Load())) {
1406 // Eliminate the load of boxed value for integer types from the cache
1407 // array by deriving the value from the index into the array.
1408 // Capture the offset of the load and then reverse the computation.
1409
1410 // Get LoadN node which loads a boxing object from 'cache' array.
1411 if (base->is_DecodeN()) {
1412 base = base->in(1);
1413 }
1414 if (!base->in(Address)->is_AddP()) {
1415 return nullptr; // Complex address
1416 }
1417 AddPNode* address = base->in(Address)->as_AddP();
1418 Node* cache_base = address->in(AddPNode::Base);
1419 if ((cache_base != nullptr) && cache_base->is_DecodeN()) {
1420 // Get ConP node which is static 'cache' field.
1421 cache_base = cache_base->in(1);
1422 }
1423 if ((cache_base != nullptr) && cache_base->is_Con()) {
1424 const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr();
1425 if ((base_type != nullptr) && base_type->is_autobox_cache()) {
1426 Node* elements[4];
1427 int shift = exact_log2(type2aelembytes(T_OBJECT));
1428 int count = address->unpack_offsets(elements, ARRAY_SIZE(elements));
1429 if (count > 0 && elements[0]->is_Con() &&
1430 (count == 1 ||
1431 (count == 2 && elements[1]->Opcode() == Op_LShiftX &&
1432 elements[1]->in(2) == igvn->intcon(shift)))) {
1433 ciObjArray* array = base_type->const_oop()->as_obj_array();
1434 // Fetch the box object cache[0] at the base of the array and get its value
1435 ciInstance* box = array->obj_at(0)->as_instance();
1436 ciInstanceKlass* ik = box->klass()->as_instance_klass();
1437 assert(ik->is_box_klass(), "sanity");
1438 assert(ik->nof_nonstatic_fields() == 1, "change following code");
1439 if (ik->nof_nonstatic_fields() == 1) {
1440 // This should be true nonstatic_field_at requires calling
1441 // nof_nonstatic_fields so check it anyway
1442 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1443 BasicType bt = c.basic_type();
1444 // Only integer types have boxing cache.
1445 assert(bt == T_BOOLEAN || bt == T_CHAR ||
1446 bt == T_BYTE || bt == T_SHORT ||
1447 bt == T_INT || bt == T_LONG, "wrong type = %s", type2name(bt));
1448 jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int();
1449 if (cache_low != (int)cache_low) {
1450 return nullptr; // should not happen since cache is array indexed by value
1451 }
1452 jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift);
1453 if (offset != (int)offset) {
1454 return nullptr; // should not happen since cache is array indexed by value
1455 }
1456 // Add up all the offsets making of the address of the load
1457 Node* result = elements[0];
1458 for (int i = 1; i < count; i++) {
1459 result = igvn->transform(new AddXNode(result, elements[i]));
1460 }
1461 // Remove the constant offset from the address and then
1462 result = igvn->transform(new AddXNode(result, igvn->MakeConX(-(int)offset)));
1463 // remove the scaling of the offset to recover the original index.
1464 if (result->Opcode() == Op_LShiftX && result->in(2) == igvn->intcon(shift)) {
1465 // Peel the shift off directly but wrap it in a dummy node
1466 // since Ideal can't return existing nodes
1467 igvn->_worklist.push(result); // remove dead node later
1468 result = new RShiftXNode(result->in(1), igvn->intcon(0));
1469 } else if (result->is_Add() && result->in(2)->is_Con() &&
1470 result->in(1)->Opcode() == Op_LShiftX &&
1471 result->in(1)->in(2) == igvn->intcon(shift)) {
1472 // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z)
1473 // but for boxing cache access we know that X<<Z will not overflow
1474 // (there is range check) so we do this optimizatrion by hand here.
1475 igvn->_worklist.push(result); // remove dead node later
1476 Node* add_con = new RShiftXNode(result->in(2), igvn->intcon(shift));
1477 result = new AddXNode(result->in(1)->in(1), igvn->transform(add_con));
1478 } else {
1479 result = new RShiftXNode(result, igvn->intcon(shift));
1480 }
1481 #ifdef _LP64
1482 if (bt != T_LONG) {
1483 result = new ConvL2INode(igvn->transform(result));
1484 }
1485 #else
1486 if (bt == T_LONG) {
1487 result = new ConvI2LNode(igvn->transform(result));
1488 }
1489 #endif
1490 // Boxing/unboxing can be done from signed & unsigned loads (e.g. LoadUB -> ... -> LoadB pair).
1491 // Need to preserve unboxing load type if it is unsigned.
1492 switch(this->Opcode()) {
1493 case Op_LoadUB:
1494 result = new AndINode(igvn->transform(result), igvn->intcon(0xFF));
1495 break;
1496 case Op_LoadUS:
1497 result = new AndINode(igvn->transform(result), igvn->intcon(0xFFFF));
1498 break;
1499 }
1500 return result;
1501 }
1502 }
1503 }
1504 }
1505 }
1506 return nullptr;
1507 }
1508
1509 static bool stable_phi(PhiNode* phi, PhaseGVN *phase) {
1510 Node* region = phi->in(0);
1511 if (region == nullptr) {
1512 return false; // Wait stable graph
1513 }
1514 uint cnt = phi->req();
1515 for (uint i = 1; i < cnt; i++) {
1516 Node* rc = region->in(i);
1517 if (rc == nullptr || phase->type(rc) == Type::TOP)
1518 return false; // Wait stable graph
1519 Node* in = phi->in(i);
1520 if (in == nullptr || phase->type(in) == Type::TOP)
1521 return false; // Wait stable graph
1522 }
1523 return true;
1524 }
1525
1526 //------------------------------split_through_phi------------------------------
1527 // Check whether a call to 'split_through_phi' would split this load through the
1528 // Phi *base*. This method is essentially a copy of the validations performed
1529 // by 'split_through_phi'. The first use of this method was in EA code as part
1530 // of simplification of allocation merges.
1531 bool LoadNode::can_split_through_phi_base(PhaseGVN* phase) {
1532 Node* mem = in(Memory);
1533 Node* address = in(Address);
1534 intptr_t ignore = 0;
1535 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1536 bool base_is_phi = (base != nullptr) && base->is_Phi();
1537
1538 if (req() > 3 || !base_is_phi) {
1539 return false;
1540 }
1541
1542 if (!mem->is_Phi()) {
1543 if (!MemNode::all_controls_dominate(mem, base->in(0)))
1544 return false;
1545 } else if (base->in(0) != mem->in(0)) {
1546 if (!MemNode::all_controls_dominate(mem, base->in(0))) {
1547 return false;
1548 }
1549 }
1550
1551 return true;
1552 }
1553
1554 //------------------------------split_through_phi------------------------------
1555 // Split instance or boxed field load through Phi.
1556 Node* LoadNode::split_through_phi(PhaseGVN* phase, bool ignore_missing_instance_id) {
1557 if (req() > 3) {
1558 assert(is_LoadVector() && Opcode() != Op_LoadVector, "load has too many inputs");
1559 // LoadVector subclasses such as LoadVectorMasked have extra inputs that the logic below doesn't take into account
1560 return nullptr;
1561 }
1562 Node* mem = in(Memory);
1563 Node* address = in(Address);
1564 const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr();
1565
1566 assert((t_oop != nullptr) &&
1567 (ignore_missing_instance_id ||
1568 t_oop->is_known_instance_field() ||
1569 t_oop->is_ptr_to_boxed_value()), "invalid conditions");
1570
1571 Compile* C = phase->C;
1572 intptr_t ignore = 0;
1573 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1574 bool base_is_phi = (base != nullptr) && base->is_Phi();
1575 bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() &&
1576 (base != nullptr) && (base == address->in(AddPNode::Base)) &&
1577 phase->type(base)->higher_equal(TypePtr::NOTNULL);
1578
1579 if (!((mem->is_Phi() || base_is_phi) &&
1580 (ignore_missing_instance_id || load_boxed_values || t_oop->is_known_instance_field()))) {
1581 return nullptr; // Neither memory or base are Phi
1582 }
1583
1584 if (mem->is_Phi()) {
1585 if (!stable_phi(mem->as_Phi(), phase)) {
1586 return nullptr; // Wait stable graph
1587 }
1588 uint cnt = mem->req();
1589 // Check for loop invariant memory.
1590 if (cnt == 3) {
1591 for (uint i = 1; i < cnt; i++) {
1592 Node* in = mem->in(i);
1593 Node* m = optimize_memory_chain(in, t_oop, this, phase);
1594 if (m == mem) {
1595 if (i == 1) {
1596 // if the first edge was a loop, check second edge too.
1597 // If both are replaceable - we are in an infinite loop
1598 Node *n = optimize_memory_chain(mem->in(2), t_oop, this, phase);
1599 if (n == mem) {
1600 break;
1601 }
1602 }
1603 set_req(Memory, mem->in(cnt - i));
1604 return this; // made change
1605 }
1606 }
1607 }
1608 }
1609 if (base_is_phi) {
1610 if (!stable_phi(base->as_Phi(), phase)) {
1611 return nullptr; // Wait stable graph
1612 }
1613 uint cnt = base->req();
1614 // Check for loop invariant memory.
1615 if (cnt == 3) {
1616 for (uint i = 1; i < cnt; i++) {
1617 if (base->in(i) == base) {
1618 return nullptr; // Wait stable graph
1619 }
1620 }
1621 }
1622 }
1623
1624 // Split through Phi (see original code in loopopts.cpp).
1625 assert(ignore_missing_instance_id || C->have_alias_type(t_oop), "instance should have alias type");
1626
1627 // Do nothing here if Identity will find a value
1628 // (to avoid infinite chain of value phis generation).
1629 if (this != Identity(phase)) {
1630 return nullptr;
1631 }
1632
1633 // Select Region to split through.
1634 Node* region;
1635 if (!base_is_phi) {
1636 assert(mem->is_Phi(), "sanity");
1637 region = mem->in(0);
1638 // Skip if the region dominates some control edge of the address.
1639 if (!MemNode::all_controls_dominate(address, region))
1640 return nullptr;
1641 } else if (!mem->is_Phi()) {
1642 assert(base_is_phi, "sanity");
1643 region = base->in(0);
1644 // Skip if the region dominates some control edge of the memory.
1645 if (!MemNode::all_controls_dominate(mem, region))
1646 return nullptr;
1647 } else if (base->in(0) != mem->in(0)) {
1648 assert(base_is_phi && mem->is_Phi(), "sanity");
1649 if (MemNode::all_controls_dominate(mem, base->in(0))) {
1650 region = base->in(0);
1651 } else if (MemNode::all_controls_dominate(address, mem->in(0))) {
1652 region = mem->in(0);
1653 } else {
1654 return nullptr; // complex graph
1655 }
1656 } else {
1657 assert(base->in(0) == mem->in(0), "sanity");
1658 region = mem->in(0);
1659 }
1660
1661 Node* phi = nullptr;
1662 const Type* this_type = this->bottom_type();
1663 PhaseIterGVN* igvn = phase->is_IterGVN();
1664 if (t_oop != nullptr && (t_oop->is_known_instance_field() || load_boxed_values)) {
1665 int this_index = C->get_alias_index(t_oop);
1666 int this_offset = t_oop->offset();
1667 int this_iid = t_oop->is_known_instance_field() ? t_oop->instance_id() : base->_idx;
1668 phi = new PhiNode(region, this_type, nullptr, mem->_idx, this_iid, this_index, this_offset);
1669 } else if (ignore_missing_instance_id) {
1670 phi = new PhiNode(region, this_type, nullptr, mem->_idx);
1671 } else {
1672 return nullptr;
1673 }
1674
1675 for (uint i = 1; i < region->req(); i++) {
1676 Node* x;
1677 Node* the_clone = nullptr;
1678 Node* in = region->in(i);
1679 if (region->is_CountedLoop() && region->as_Loop()->is_strip_mined() && i == LoopNode::EntryControl &&
1680 in != nullptr && in->is_OuterStripMinedLoop()) {
1681 // No node should go in the outer strip mined loop
1682 in = in->in(LoopNode::EntryControl);
1683 }
1684 if (in == nullptr || in == C->top()) {
1685 x = C->top(); // Dead path? Use a dead data op
1686 } else {
1687 x = this->clone(); // Else clone up the data op
1688 the_clone = x; // Remember for possible deletion.
1689 // Alter data node to use pre-phi inputs
1690 if (this->in(0) == region) {
1691 x->set_req(0, in);
1692 } else {
1693 x->set_req(0, nullptr);
1694 }
1695 if (mem->is_Phi() && (mem->in(0) == region)) {
1696 x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone.
1697 }
1698 if (address->is_Phi() && address->in(0) == region) {
1699 x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone
1700 }
1701 if (base_is_phi && (base->in(0) == region)) {
1702 Node* base_x = base->in(i); // Clone address for loads from boxed objects.
1703 Node* adr_x = phase->transform(new AddPNode(base_x,base_x,address->in(AddPNode::Offset)));
1704 x->set_req(Address, adr_x);
1705 }
1706 }
1707 // Check for a 'win' on some paths
1708 const Type *t = x->Value(igvn);
1709
1710 bool singleton = t->singleton();
1711
1712 // See comments in PhaseIdealLoop::split_thru_phi().
1713 if (singleton && t == Type::TOP) {
1714 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1715 }
1716
1717 if (singleton) {
1718 x = igvn->makecon(t);
1719 } else {
1720 // We now call Identity to try to simplify the cloned node.
1721 // Note that some Identity methods call phase->type(this).
1722 // Make sure that the type array is big enough for
1723 // our new node, even though we may throw the node away.
1724 // (This tweaking with igvn only works because x is a new node.)
1725 igvn->set_type(x, t);
1726 // If x is a TypeNode, capture any more-precise type permanently into Node
1727 // otherwise it will be not updated during igvn->transform since
1728 // igvn->type(x) is set to x->Value() already.
1729 x->raise_bottom_type(t);
1730 Node* y = x->Identity(igvn);
1731 if (y != x) {
1732 x = y;
1733 } else {
1734 y = igvn->hash_find_insert(x);
1735 if (y) {
1736 x = y;
1737 } else {
1738 // Else x is a new node we are keeping
1739 // We do not need register_new_node_with_optimizer
1740 // because set_type has already been called.
1741 igvn->_worklist.push(x);
1742 }
1743 }
1744 }
1745 if (x != the_clone && the_clone != nullptr) {
1746 igvn->remove_dead_node(the_clone);
1747 }
1748 phi->set_req(i, x);
1749 }
1750 // Record Phi
1751 igvn->register_new_node_with_optimizer(phi);
1752 return phi;
1753 }
1754
1755 AllocateNode* LoadNode::is_new_object_mark_load() const {
1756 if (Opcode() == Op_LoadX) {
1757 Node* address = in(MemNode::Address);
1758 AllocateNode* alloc = AllocateNode::Ideal_allocation(address);
1759 Node* mem = in(MemNode::Memory);
1760 if (alloc != nullptr && mem->is_Proj() &&
1761 mem->in(0) != nullptr &&
1762 mem->in(0) == alloc->initialization() &&
1763 alloc->initialization()->proj_out_or_null(0) != nullptr) {
1764 return alloc;
1765 }
1766 }
1767 return nullptr;
1768 }
1769
1770
1771 //------------------------------Ideal------------------------------------------
1772 // If the load is from Field memory and the pointer is non-null, it might be possible to
1773 // zero out the control input.
1774 // If the offset is constant and the base is an object allocation,
1775 // try to hook me up to the exact initializing store.
1776 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1777 if (has_pinned_control_dependency()) {
1778 return nullptr;
1779 }
1780 Node* p = MemNode::Ideal_common(phase, can_reshape);
1781 if (p) return (p == NodeSentinel) ? nullptr : p;
1782
1783 Node* ctrl = in(MemNode::Control);
1784 Node* address = in(MemNode::Address);
1785 bool progress = false;
1786
1787 bool addr_mark = ((phase->type(address)->isa_oopptr() || phase->type(address)->isa_narrowoop()) &&
1788 phase->type(address)->is_ptr()->offset() == oopDesc::mark_offset_in_bytes());
1789
1790 // Skip up past a SafePoint control. Cannot do this for Stores because
1791 // pointer stores & cardmarks must stay on the same side of a SafePoint.
1792 if( ctrl != nullptr && ctrl->Opcode() == Op_SafePoint &&
1793 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw &&
1794 !addr_mark &&
1795 (depends_only_on_test() || has_unknown_control_dependency())) {
1796 ctrl = ctrl->in(0);
1797 set_req(MemNode::Control,ctrl);
1798 progress = true;
1799 }
1800
1801 intptr_t ignore = 0;
1802 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1803 if (base != nullptr
1804 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
1805 // Check for useless control edge in some common special cases
1806 if (in(MemNode::Control) != nullptr
1807 && can_remove_control()
1808 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1809 && all_controls_dominate(base, phase->C->start())) {
1810 // A method-invariant, non-null address (constant or 'this' argument).
1811 set_req(MemNode::Control, nullptr);
1812 progress = true;
1813 }
1814 }
1815
1816 Node* mem = in(MemNode::Memory);
1817 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1818
1819 if (can_reshape && (addr_t != nullptr)) {
1820 // try to optimize our memory input
1821 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase);
1822 if (opt_mem != mem) {
1823 set_req_X(MemNode::Memory, opt_mem, phase);
1824 if (phase->type( opt_mem ) == Type::TOP) return nullptr;
1825 return this;
1826 }
1827 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1828 if ((t_oop != nullptr) &&
1829 (t_oop->is_known_instance_field() ||
1830 t_oop->is_ptr_to_boxed_value())) {
1831 PhaseIterGVN *igvn = phase->is_IterGVN();
1832 assert(igvn != nullptr, "must be PhaseIterGVN when can_reshape is true");
1833 if (igvn->_worklist.member(opt_mem)) {
1834 // Delay this transformation until memory Phi is processed.
1835 igvn->_worklist.push(this);
1836 return nullptr;
1837 }
1838 // Split instance field load through Phi.
1839 Node* result = split_through_phi(phase);
1840 if (result != nullptr) return result;
1841
1842 if (t_oop->is_ptr_to_boxed_value()) {
1843 Node* result = eliminate_autobox(igvn);
1844 if (result != nullptr) return result;
1845 }
1846 }
1847 }
1848
1849 // Is there a dominating load that loads the same value? Leave
1850 // anything that is not a load of a field/array element (like
1851 // barriers etc.) alone
1852 if (in(0) != nullptr && !adr_type()->isa_rawptr() && can_reshape) {
1853 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) {
1854 Node *use = mem->fast_out(i);
1855 if (use != this &&
1856 use->Opcode() == Opcode() &&
1857 use->in(0) != nullptr &&
1858 use->in(0) != in(0) &&
1859 use->in(Address) == in(Address)) {
1860 Node* ctl = in(0);
1861 for (int i = 0; i < 10 && ctl != nullptr; i++) {
1862 ctl = IfNode::up_one_dom(ctl);
1863 if (ctl == use->in(0)) {
1864 set_req(0, use->in(0));
1865 return this;
1866 }
1867 }
1868 }
1869 }
1870 }
1871
1872 // Check for prior store with a different base or offset; make Load
1873 // independent. Skip through any number of them. Bail out if the stores
1874 // are in an endless dead cycle and report no progress. This is a key
1875 // transform for Reflection. However, if after skipping through the Stores
1876 // we can't then fold up against a prior store do NOT do the transform as
1877 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
1878 // array memory alive twice: once for the hoisted Load and again after the
1879 // bypassed Store. This situation only works if EVERYBODY who does
1880 // anti-dependence work knows how to bypass. I.e. we need all
1881 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
1882 // the alias index stuff. So instead, peek through Stores and IFF we can
1883 // fold up, do so.
1884 Node* prev_mem = find_previous_store(phase);
1885 if (prev_mem != nullptr) {
1886 Node* value = can_see_arraycopy_value(prev_mem, phase);
1887 if (value != nullptr) {
1888 return value;
1889 }
1890 }
1891 // Steps (a), (b): Walk past independent stores to find an exact match.
1892 if (prev_mem != nullptr && prev_mem != in(MemNode::Memory)) {
1893 // (c) See if we can fold up on the spot, but don't fold up here.
1894 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
1895 // just return a prior value, which is done by Identity calls.
1896 if (can_see_stored_value(prev_mem, phase)) {
1897 // Make ready for step (d):
1898 set_req_X(MemNode::Memory, prev_mem, phase);
1899 return this;
1900 }
1901 }
1902
1903 return progress ? this : nullptr;
1904 }
1905
1906 // Helper to recognize certain Klass fields which are invariant across
1907 // some group of array types (e.g., int[] or all T[] where T < Object).
1908 const Type*
1909 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1910 ciKlass* klass) const {
1911 if (tkls->offset() == in_bytes(Klass::modifier_flags_offset())) {
1912 // The field is Klass::_modifier_flags. Return its (constant) value.
1913 // (Folds up the 2nd indirection in aClassConstant.getModifiers().)
1914 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags");
1915 return TypeInt::make(klass->modifier_flags());
1916 }
1917 if (tkls->offset() == in_bytes(Klass::access_flags_offset())) {
1918 // The field is Klass::_access_flags. Return its (constant) value.
1919 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1920 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags");
1921 return TypeInt::make(klass->access_flags());
1922 }
1923 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) {
1924 // The field is Klass::_layout_helper. Return its constant value if known.
1925 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper");
1926 return TypeInt::make(klass->layout_helper());
1927 }
1928
1929 // No match.
1930 return nullptr;
1931 }
1932
1933 //------------------------------Value-----------------------------------------
1934 const Type* LoadNode::Value(PhaseGVN* phase) const {
1935 // Either input is TOP ==> the result is TOP
1936 Node* mem = in(MemNode::Memory);
1937 const Type *t1 = phase->type(mem);
1938 if (t1 == Type::TOP) return Type::TOP;
1939 Node* adr = in(MemNode::Address);
1940 const TypePtr* tp = phase->type(adr)->isa_ptr();
1941 if (tp == nullptr || tp->empty()) return Type::TOP;
1942 int off = tp->offset();
1943 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
1944 Compile* C = phase->C;
1945
1946 // Try to guess loaded type from pointer type
1947 if (tp->isa_aryptr()) {
1948 const TypeAryPtr* ary = tp->is_aryptr();
1949 const Type* t = ary->elem();
1950
1951 // Determine whether the reference is beyond the header or not, by comparing
1952 // the offset against the offset of the start of the array's data.
1953 // Different array types begin at slightly different offsets (12 vs. 16).
1954 // We choose T_BYTE as an example base type that is least restrictive
1955 // as to alignment, which will therefore produce the smallest
1956 // possible base offset.
1957 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
1958 const bool off_beyond_header = (off >= min_base_off);
1959
1960 // Try to constant-fold a stable array element.
1961 if (FoldStableValues && !is_mismatched_access() && ary->is_stable()) {
1962 // Make sure the reference is not into the header and the offset is constant
1963 ciObject* aobj = ary->const_oop();
1964 if (aobj != nullptr && off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) {
1965 int stable_dimension = (ary->stable_dimension() > 0 ? ary->stable_dimension() - 1 : 0);
1966 const Type* con_type = Type::make_constant_from_array_element(aobj->as_array(), off,
1967 stable_dimension,
1968 memory_type(), is_unsigned());
1969 if (con_type != nullptr) {
1970 return con_type;
1971 }
1972 }
1973 }
1974
1975 // Don't do this for integer types. There is only potential profit if
1976 // the element type t is lower than _type; that is, for int types, if _type is
1977 // more restrictive than t. This only happens here if one is short and the other
1978 // char (both 16 bits), and in those cases we've made an intentional decision
1979 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
1980 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
1981 //
1982 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
1983 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
1984 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
1985 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
1986 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
1987 // In fact, that could have been the original type of p1, and p1 could have
1988 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
1989 // expression (LShiftL quux 3) independently optimized to the constant 8.
1990 if ((t->isa_int() == nullptr) && (t->isa_long() == nullptr)
1991 && (_type->isa_vect() == nullptr)
1992 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
1993 // t might actually be lower than _type, if _type is a unique
1994 // concrete subclass of abstract class t.
1995 if (off_beyond_header || off == Type::OffsetBot) { // is the offset beyond the header?
1996 const Type* jt = t->join_speculative(_type);
1997 // In any case, do not allow the join, per se, to empty out the type.
1998 if (jt->empty() && !t->empty()) {
1999 // This can happen if a interface-typed array narrows to a class type.
2000 jt = _type;
2001 }
2002 #ifdef ASSERT
2003 if (phase->C->eliminate_boxing() && adr->is_AddP()) {
2004 // The pointers in the autobox arrays are always non-null
2005 Node* base = adr->in(AddPNode::Base);
2006 if ((base != nullptr) && base->is_DecodeN()) {
2007 // Get LoadN node which loads IntegerCache.cache field
2008 base = base->in(1);
2009 }
2010 if ((base != nullptr) && base->is_Con()) {
2011 const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr();
2012 if ((base_type != nullptr) && base_type->is_autobox_cache()) {
2013 // It could be narrow oop
2014 assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity");
2015 }
2016 }
2017 }
2018 #endif
2019 return jt;
2020 }
2021 }
2022 } else if (tp->base() == Type::InstPtr) {
2023 assert( off != Type::OffsetBot ||
2024 // arrays can be cast to Objects
2025 !tp->isa_instptr() ||
2026 tp->is_instptr()->instance_klass()->is_java_lang_Object() ||
2027 // unsafe field access may not have a constant offset
2028 C->has_unsafe_access(),
2029 "Field accesses must be precise" );
2030 // For oop loads, we expect the _type to be precise.
2031
2032 // Optimize loads from constant fields.
2033 const TypeInstPtr* tinst = tp->is_instptr();
2034 ciObject* const_oop = tinst->const_oop();
2035 if (!is_mismatched_access() && off != Type::OffsetBot && const_oop != nullptr && const_oop->is_instance()) {
2036 const Type* con_type = Type::make_constant_from_field(const_oop->as_instance(), off, is_unsigned(), memory_type());
2037 if (con_type != nullptr) {
2038 return con_type;
2039 }
2040 }
2041 } else if (tp->base() == Type::KlassPtr || tp->base() == Type::InstKlassPtr || tp->base() == Type::AryKlassPtr) {
2042 assert(off != Type::OffsetBot ||
2043 !tp->isa_instklassptr() ||
2044 // arrays can be cast to Objects
2045 tp->isa_instklassptr()->instance_klass()->is_java_lang_Object() ||
2046 // also allow array-loading from the primary supertype
2047 // array during subtype checks
2048 Opcode() == Op_LoadKlass,
2049 "Field accesses must be precise");
2050 // For klass/static loads, we expect the _type to be precise
2051 } else if (tp->base() == Type::RawPtr && adr->is_Load() && off == 0) {
2052 /* With mirrors being an indirect in the Klass*
2053 * the VM is now using two loads. LoadKlass(LoadP(LoadP(Klass, mirror_offset), zero_offset))
2054 * The LoadP from the Klass has a RawPtr type (see LibraryCallKit::load_mirror_from_klass).
2055 *
2056 * So check the type and klass of the node before the LoadP.
2057 */
2058 Node* adr2 = adr->in(MemNode::Address);
2059 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2060 if (tkls != nullptr && !StressReflectiveCode) {
2061 if (tkls->is_loaded() && tkls->klass_is_exact() && tkls->offset() == in_bytes(Klass::java_mirror_offset())) {
2062 ciKlass* klass = tkls->exact_klass();
2063 assert(adr->Opcode() == Op_LoadP, "must load an oop from _java_mirror");
2064 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
2065 return TypeInstPtr::make(klass->java_mirror());
2066 }
2067 }
2068 }
2069
2070 const TypeKlassPtr *tkls = tp->isa_klassptr();
2071 if (tkls != nullptr) {
2072 if (tkls->is_loaded() && tkls->klass_is_exact()) {
2073 ciKlass* klass = tkls->exact_klass();
2074 // We are loading a field from a Klass metaobject whose identity
2075 // is known at compile time (the type is "exact" or "precise").
2076 // Check for fields we know are maintained as constants by the VM.
2077 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) {
2078 // The field is Klass::_super_check_offset. Return its (constant) value.
2079 // (Folds up type checking code.)
2080 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
2081 return TypeInt::make(klass->super_check_offset());
2082 }
2083 // Compute index into primary_supers array
2084 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
2085 // Check for overflowing; use unsigned compare to handle the negative case.
2086 if( depth < ciKlass::primary_super_limit() ) {
2087 // The field is an element of Klass::_primary_supers. Return its (constant) value.
2088 // (Folds up type checking code.)
2089 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
2090 ciKlass *ss = klass->super_of_depth(depth);
2091 return ss ? TypeKlassPtr::make(ss, Type::trust_interfaces) : TypePtr::NULL_PTR;
2092 }
2093 const Type* aift = load_array_final_field(tkls, klass);
2094 if (aift != nullptr) return aift;
2095 }
2096
2097 // We can still check if we are loading from the primary_supers array at a
2098 // shallow enough depth. Even though the klass is not exact, entries less
2099 // than or equal to its super depth are correct.
2100 if (tkls->is_loaded()) {
2101 ciKlass* klass = nullptr;
2102 if (tkls->isa_instklassptr()) {
2103 klass = tkls->is_instklassptr()->instance_klass();
2104 } else {
2105 int dims;
2106 const Type* inner = tkls->is_aryklassptr()->base_element_type(dims);
2107 if (inner->isa_instklassptr()) {
2108 klass = inner->is_instklassptr()->instance_klass();
2109 klass = ciObjArrayKlass::make(klass, dims);
2110 }
2111 }
2112 if (klass != nullptr) {
2113 // Compute index into primary_supers array
2114 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
2115 // Check for overflowing; use unsigned compare to handle the negative case.
2116 if (depth < ciKlass::primary_super_limit() &&
2117 depth <= klass->super_depth()) { // allow self-depth checks to handle self-check case
2118 // The field is an element of Klass::_primary_supers. Return its (constant) value.
2119 // (Folds up type checking code.)
2120 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
2121 ciKlass *ss = klass->super_of_depth(depth);
2122 return ss ? TypeKlassPtr::make(ss, Type::trust_interfaces) : TypePtr::NULL_PTR;
2123 }
2124 }
2125 }
2126
2127 // If the type is enough to determine that the thing is not an array,
2128 // we can give the layout_helper a positive interval type.
2129 // This will help short-circuit some reflective code.
2130 if (tkls->offset() == in_bytes(Klass::layout_helper_offset()) &&
2131 tkls->isa_instklassptr() && // not directly typed as an array
2132 !tkls->is_instklassptr()->instance_klass()->is_java_lang_Object() // not the supertype of all T[] and specifically not Serializable & Cloneable
2133 ) {
2134 // Note: When interfaces are reliable, we can narrow the interface
2135 // test to (klass != Serializable && klass != Cloneable).
2136 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
2137 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
2138 // The key property of this type is that it folds up tests
2139 // for array-ness, since it proves that the layout_helper is positive.
2140 // Thus, a generic value like the basic object layout helper works fine.
2141 return TypeInt::make(min_size, max_jint, Type::WidenMin);
2142 }
2143 }
2144
2145 // If we are loading from a freshly-allocated object, produce a zero,
2146 // if the load is provably beyond the header of the object.
2147 // (Also allow a variable load from a fresh array to produce zero.)
2148 const TypeOopPtr *tinst = tp->isa_oopptr();
2149 bool is_instance = (tinst != nullptr) && tinst->is_known_instance_field();
2150 bool is_boxed_value = (tinst != nullptr) && tinst->is_ptr_to_boxed_value();
2151 if (ReduceFieldZeroing || is_instance || is_boxed_value) {
2152 Node* value = can_see_stored_value(mem,phase);
2153 if (value != nullptr && value->is_Con()) {
2154 assert(value->bottom_type()->higher_equal(_type),"sanity");
2155 return value->bottom_type();
2156 }
2157 }
2158
2159 bool is_vect = (_type->isa_vect() != nullptr);
2160 if (is_instance && !is_vect) {
2161 // If we have an instance type and our memory input is the
2162 // programs's initial memory state, there is no matching store,
2163 // so just return a zero of the appropriate type -
2164 // except if it is vectorized - then we have no zero constant.
2165 Node *mem = in(MemNode::Memory);
2166 if (mem->is_Parm() && mem->in(0)->is_Start()) {
2167 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
2168 return Type::get_zero_type(_type->basic_type());
2169 }
2170 }
2171
2172 Node* alloc = is_new_object_mark_load();
2173 if (alloc != nullptr) {
2174 return TypeX::make(markWord::prototype().value());
2175 }
2176
2177 return _type;
2178 }
2179
2180 //------------------------------match_edge-------------------------------------
2181 // Do we Match on this edge index or not? Match only the address.
2182 uint LoadNode::match_edge(uint idx) const {
2183 return idx == MemNode::Address;
2184 }
2185
2186 //--------------------------LoadBNode::Ideal--------------------------------------
2187 //
2188 // If the previous store is to the same address as this load,
2189 // and the value stored was larger than a byte, replace this load
2190 // with the value stored truncated to a byte. If no truncation is
2191 // needed, the replacement is done in LoadNode::Identity().
2192 //
2193 Node* LoadBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2194 Node* mem = in(MemNode::Memory);
2195 Node* value = can_see_stored_value(mem,phase);
2196 if (value != nullptr) {
2197 Node* narrow = Compile::narrow_value(T_BYTE, value, _type, phase, false);
2198 if (narrow != value) {
2199 return narrow;
2200 }
2201 }
2202 // Identity call will handle the case where truncation is not needed.
2203 return LoadNode::Ideal(phase, can_reshape);
2204 }
2205
2206 const Type* LoadBNode::Value(PhaseGVN* phase) const {
2207 Node* mem = in(MemNode::Memory);
2208 Node* value = can_see_stored_value(mem,phase);
2209 if (value != nullptr && value->is_Con() &&
2210 !value->bottom_type()->higher_equal(_type)) {
2211 // If the input to the store does not fit with the load's result type,
2212 // it must be truncated. We can't delay until Ideal call since
2213 // a singleton Value is needed for split_thru_phi optimization.
2214 int con = value->get_int();
2215 return TypeInt::make((con << 24) >> 24);
2216 }
2217 return LoadNode::Value(phase);
2218 }
2219
2220 //--------------------------LoadUBNode::Ideal-------------------------------------
2221 //
2222 // If the previous store is to the same address as this load,
2223 // and the value stored was larger than a byte, replace this load
2224 // with the value stored truncated to a byte. If no truncation is
2225 // needed, the replacement is done in LoadNode::Identity().
2226 //
2227 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2228 Node* mem = in(MemNode::Memory);
2229 Node* value = can_see_stored_value(mem, phase);
2230 if (value != nullptr) {
2231 Node* narrow = Compile::narrow_value(T_BOOLEAN, value, _type, phase, false);
2232 if (narrow != value) {
2233 return narrow;
2234 }
2235 }
2236 // Identity call will handle the case where truncation is not needed.
2237 return LoadNode::Ideal(phase, can_reshape);
2238 }
2239
2240 const Type* LoadUBNode::Value(PhaseGVN* phase) const {
2241 Node* mem = in(MemNode::Memory);
2242 Node* value = can_see_stored_value(mem,phase);
2243 if (value != nullptr && value->is_Con() &&
2244 !value->bottom_type()->higher_equal(_type)) {
2245 // If the input to the store does not fit with the load's result type,
2246 // it must be truncated. We can't delay until Ideal call since
2247 // a singleton Value is needed for split_thru_phi optimization.
2248 int con = value->get_int();
2249 return TypeInt::make(con & 0xFF);
2250 }
2251 return LoadNode::Value(phase);
2252 }
2253
2254 //--------------------------LoadUSNode::Ideal-------------------------------------
2255 //
2256 // If the previous store is to the same address as this load,
2257 // and the value stored was larger than a char, replace this load
2258 // with the value stored truncated to a char. If no truncation is
2259 // needed, the replacement is done in LoadNode::Identity().
2260 //
2261 Node* LoadUSNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2262 Node* mem = in(MemNode::Memory);
2263 Node* value = can_see_stored_value(mem,phase);
2264 if (value != nullptr) {
2265 Node* narrow = Compile::narrow_value(T_CHAR, value, _type, phase, false);
2266 if (narrow != value) {
2267 return narrow;
2268 }
2269 }
2270 // Identity call will handle the case where truncation is not needed.
2271 return LoadNode::Ideal(phase, can_reshape);
2272 }
2273
2274 const Type* LoadUSNode::Value(PhaseGVN* phase) const {
2275 Node* mem = in(MemNode::Memory);
2276 Node* value = can_see_stored_value(mem,phase);
2277 if (value != nullptr && value->is_Con() &&
2278 !value->bottom_type()->higher_equal(_type)) {
2279 // If the input to the store does not fit with the load's result type,
2280 // it must be truncated. We can't delay until Ideal call since
2281 // a singleton Value is needed for split_thru_phi optimization.
2282 int con = value->get_int();
2283 return TypeInt::make(con & 0xFFFF);
2284 }
2285 return LoadNode::Value(phase);
2286 }
2287
2288 //--------------------------LoadSNode::Ideal--------------------------------------
2289 //
2290 // If the previous store is to the same address as this load,
2291 // and the value stored was larger than a short, replace this load
2292 // with the value stored truncated to a short. If no truncation is
2293 // needed, the replacement is done in LoadNode::Identity().
2294 //
2295 Node* LoadSNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2296 Node* mem = in(MemNode::Memory);
2297 Node* value = can_see_stored_value(mem,phase);
2298 if (value != nullptr) {
2299 Node* narrow = Compile::narrow_value(T_SHORT, value, _type, phase, false);
2300 if (narrow != value) {
2301 return narrow;
2302 }
2303 }
2304 // Identity call will handle the case where truncation is not needed.
2305 return LoadNode::Ideal(phase, can_reshape);
2306 }
2307
2308 const Type* LoadSNode::Value(PhaseGVN* phase) const {
2309 Node* mem = in(MemNode::Memory);
2310 Node* value = can_see_stored_value(mem,phase);
2311 if (value != nullptr && value->is_Con() &&
2312 !value->bottom_type()->higher_equal(_type)) {
2313 // If the input to the store does not fit with the load's result type,
2314 // it must be truncated. We can't delay until Ideal call since
2315 // a singleton Value is needed for split_thru_phi optimization.
2316 int con = value->get_int();
2317 return TypeInt::make((con << 16) >> 16);
2318 }
2319 return LoadNode::Value(phase);
2320 }
2321
2322 //=============================================================================
2323 //----------------------------LoadKlassNode::make------------------------------
2324 // Polymorphic factory method:
2325 Node* LoadKlassNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* at, const TypeKlassPtr* tk) {
2326 // sanity check the alias category against the created node type
2327 const TypePtr *adr_type = adr->bottom_type()->isa_ptr();
2328 assert(adr_type != nullptr, "expecting TypeKlassPtr");
2329 #ifdef _LP64
2330 if (adr_type->is_ptr_to_narrowklass()) {
2331 assert(UseCompressedClassPointers, "no compressed klasses");
2332 Node* load_klass = gvn.transform(new LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowklass(), MemNode::unordered));
2333 return new DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr());
2334 }
2335 #endif
2336 assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
2337 return new LoadKlassNode(ctl, mem, adr, at, tk, MemNode::unordered);
2338 }
2339
2340 //------------------------------Value------------------------------------------
2341 const Type* LoadKlassNode::Value(PhaseGVN* phase) const {
2342 return klass_value_common(phase);
2343 }
2344
2345 // In most cases, LoadKlassNode does not have the control input set. If the control
2346 // input is set, it must not be removed (by LoadNode::Ideal()).
2347 bool LoadKlassNode::can_remove_control() const {
2348 return false;
2349 }
2350
2351 const Type* LoadNode::klass_value_common(PhaseGVN* phase) const {
2352 // Either input is TOP ==> the result is TOP
2353 const Type *t1 = phase->type( in(MemNode::Memory) );
2354 if (t1 == Type::TOP) return Type::TOP;
2355 Node *adr = in(MemNode::Address);
2356 const Type *t2 = phase->type( adr );
2357 if (t2 == Type::TOP) return Type::TOP;
2358 const TypePtr *tp = t2->is_ptr();
2359 if (TypePtr::above_centerline(tp->ptr()) ||
2360 tp->ptr() == TypePtr::Null) return Type::TOP;
2361
2362 // Return a more precise klass, if possible
2363 const TypeInstPtr *tinst = tp->isa_instptr();
2364 if (tinst != nullptr) {
2365 ciInstanceKlass* ik = tinst->instance_klass();
2366 int offset = tinst->offset();
2367 if (ik == phase->C->env()->Class_klass()
2368 && (offset == java_lang_Class::klass_offset() ||
2369 offset == java_lang_Class::array_klass_offset())) {
2370 // We are loading a special hidden field from a Class mirror object,
2371 // the field which points to the VM's Klass metaobject.
2372 ciType* t = tinst->java_mirror_type();
2373 // java_mirror_type returns non-null for compile-time Class constants.
2374 if (t != nullptr) {
2375 // constant oop => constant klass
2376 if (offset == java_lang_Class::array_klass_offset()) {
2377 if (t->is_void()) {
2378 // We cannot create a void array. Since void is a primitive type return null
2379 // klass. Users of this result need to do a null check on the returned klass.
2380 return TypePtr::NULL_PTR;
2381 }
2382 return TypeKlassPtr::make(ciArrayKlass::make(t), Type::trust_interfaces);
2383 }
2384 if (!t->is_klass()) {
2385 // a primitive Class (e.g., int.class) has null for a klass field
2386 return TypePtr::NULL_PTR;
2387 }
2388 // (Folds up the 1st indirection in aClassConstant.getModifiers().)
2389 return TypeKlassPtr::make(t->as_klass(), Type::trust_interfaces);
2390 }
2391 // non-constant mirror, so we can't tell what's going on
2392 }
2393 if (!tinst->is_loaded())
2394 return _type; // Bail out if not loaded
2395 if (offset == oopDesc::klass_offset_in_bytes()) {
2396 return tinst->as_klass_type(true);
2397 }
2398 }
2399
2400 // Check for loading klass from an array
2401 const TypeAryPtr *tary = tp->isa_aryptr();
2402 if (tary != nullptr &&
2403 tary->offset() == oopDesc::klass_offset_in_bytes()) {
2404 return tary->as_klass_type(true);
2405 }
2406
2407 // Check for loading klass from an array klass
2408 const TypeKlassPtr *tkls = tp->isa_klassptr();
2409 if (tkls != nullptr && !StressReflectiveCode) {
2410 if (!tkls->is_loaded())
2411 return _type; // Bail out if not loaded
2412 if (tkls->isa_aryklassptr() && tkls->is_aryklassptr()->elem()->isa_klassptr() &&
2413 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) {
2414 // // Always returning precise element type is incorrect,
2415 // // e.g., element type could be object and array may contain strings
2416 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
2417
2418 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
2419 // according to the element type's subclassing.
2420 return tkls->is_aryklassptr()->elem()->isa_klassptr()->cast_to_exactness(tkls->klass_is_exact());
2421 }
2422 if (tkls->isa_instklassptr() != nullptr && tkls->klass_is_exact() &&
2423 tkls->offset() == in_bytes(Klass::super_offset())) {
2424 ciKlass* sup = tkls->is_instklassptr()->instance_klass()->super();
2425 // The field is Klass::_super. Return its (constant) value.
2426 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
2427 return sup ? TypeKlassPtr::make(sup, Type::trust_interfaces) : TypePtr::NULL_PTR;
2428 }
2429 }
2430
2431 // Bailout case
2432 return LoadNode::Value(phase);
2433 }
2434
2435 //------------------------------Identity---------------------------------------
2436 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
2437 // Also feed through the klass in Allocate(...klass...)._klass.
2438 Node* LoadKlassNode::Identity(PhaseGVN* phase) {
2439 return klass_identity_common(phase);
2440 }
2441
2442 Node* LoadNode::klass_identity_common(PhaseGVN* phase) {
2443 Node* x = LoadNode::Identity(phase);
2444 if (x != this) return x;
2445
2446 // Take apart the address into an oop and offset.
2447 // Return 'this' if we cannot.
2448 Node* adr = in(MemNode::Address);
2449 intptr_t offset = 0;
2450 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2451 if (base == nullptr) return this;
2452 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
2453 if (toop == nullptr) return this;
2454
2455 // Step over potential GC barrier for OopHandle resolve
2456 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
2457 if (bs->is_gc_barrier_node(base)) {
2458 base = bs->step_over_gc_barrier(base);
2459 }
2460
2461 // We can fetch the klass directly through an AllocateNode.
2462 // This works even if the klass is not constant (clone or newArray).
2463 if (offset == oopDesc::klass_offset_in_bytes()) {
2464 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
2465 if (allocated_klass != nullptr) {
2466 return allocated_klass;
2467 }
2468 }
2469
2470 // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*.
2471 // See inline_native_Class_query for occurrences of these patterns.
2472 // Java Example: x.getClass().isAssignableFrom(y)
2473 //
2474 // This improves reflective code, often making the Class
2475 // mirror go completely dead. (Current exception: Class
2476 // mirrors may appear in debug info, but we could clean them out by
2477 // introducing a new debug info operator for Klass.java_mirror).
2478
2479 if (toop->isa_instptr() && toop->is_instptr()->instance_klass() == phase->C->env()->Class_klass()
2480 && offset == java_lang_Class::klass_offset()) {
2481 if (base->is_Load()) {
2482 Node* base2 = base->in(MemNode::Address);
2483 if (base2->is_Load()) { /* direct load of a load which is the OopHandle */
2484 Node* adr2 = base2->in(MemNode::Address);
2485 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2486 if (tkls != nullptr && !tkls->empty()
2487 && (tkls->isa_instklassptr() || tkls->isa_aryklassptr())
2488 && adr2->is_AddP()
2489 ) {
2490 int mirror_field = in_bytes(Klass::java_mirror_offset());
2491 if (tkls->offset() == mirror_field) {
2492 return adr2->in(AddPNode::Base);
2493 }
2494 }
2495 }
2496 }
2497 }
2498
2499 return this;
2500 }
2501
2502
2503 //------------------------------Value------------------------------------------
2504 const Type* LoadNKlassNode::Value(PhaseGVN* phase) const {
2505 const Type *t = klass_value_common(phase);
2506 if (t == Type::TOP)
2507 return t;
2508
2509 return t->make_narrowklass();
2510 }
2511
2512 //------------------------------Identity---------------------------------------
2513 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
2514 // Also feed through the klass in Allocate(...klass...)._klass.
2515 Node* LoadNKlassNode::Identity(PhaseGVN* phase) {
2516 Node *x = klass_identity_common(phase);
2517
2518 const Type *t = phase->type( x );
2519 if( t == Type::TOP ) return x;
2520 if( t->isa_narrowklass()) return x;
2521 assert (!t->isa_narrowoop(), "no narrow oop here");
2522
2523 return phase->transform(new EncodePKlassNode(x, t->make_narrowklass()));
2524 }
2525
2526 //------------------------------Value-----------------------------------------
2527 const Type* LoadRangeNode::Value(PhaseGVN* phase) const {
2528 // Either input is TOP ==> the result is TOP
2529 const Type *t1 = phase->type( in(MemNode::Memory) );
2530 if( t1 == Type::TOP ) return Type::TOP;
2531 Node *adr = in(MemNode::Address);
2532 const Type *t2 = phase->type( adr );
2533 if( t2 == Type::TOP ) return Type::TOP;
2534 const TypePtr *tp = t2->is_ptr();
2535 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
2536 const TypeAryPtr *tap = tp->isa_aryptr();
2537 if( !tap ) return _type;
2538 return tap->size();
2539 }
2540
2541 //-------------------------------Ideal---------------------------------------
2542 // Feed through the length in AllocateArray(...length...)._length.
2543 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2544 Node* p = MemNode::Ideal_common(phase, can_reshape);
2545 if (p) return (p == NodeSentinel) ? nullptr : p;
2546
2547 // Take apart the address into an oop and offset.
2548 // Return 'this' if we cannot.
2549 Node* adr = in(MemNode::Address);
2550 intptr_t offset = 0;
2551 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2552 if (base == nullptr) return nullptr;
2553 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2554 if (tary == nullptr) return nullptr;
2555
2556 // We can fetch the length directly through an AllocateArrayNode.
2557 // This works even if the length is not constant (clone or newArray).
2558 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2559 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base);
2560 if (alloc != nullptr) {
2561 Node* allocated_length = alloc->Ideal_length();
2562 Node* len = alloc->make_ideal_length(tary, phase);
2563 if (allocated_length != len) {
2564 // New CastII improves on this.
2565 return len;
2566 }
2567 }
2568 }
2569
2570 return nullptr;
2571 }
2572
2573 //------------------------------Identity---------------------------------------
2574 // Feed through the length in AllocateArray(...length...)._length.
2575 Node* LoadRangeNode::Identity(PhaseGVN* phase) {
2576 Node* x = LoadINode::Identity(phase);
2577 if (x != this) return x;
2578
2579 // Take apart the address into an oop and offset.
2580 // Return 'this' if we cannot.
2581 Node* adr = in(MemNode::Address);
2582 intptr_t offset = 0;
2583 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2584 if (base == nullptr) return this;
2585 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2586 if (tary == nullptr) return this;
2587
2588 // We can fetch the length directly through an AllocateArrayNode.
2589 // This works even if the length is not constant (clone or newArray).
2590 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2591 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base);
2592 if (alloc != nullptr) {
2593 Node* allocated_length = alloc->Ideal_length();
2594 // Do not allow make_ideal_length to allocate a CastII node.
2595 Node* len = alloc->make_ideal_length(tary, phase, false);
2596 if (allocated_length == len) {
2597 // Return allocated_length only if it would not be improved by a CastII.
2598 return allocated_length;
2599 }
2600 }
2601 }
2602
2603 return this;
2604
2605 }
2606
2607 //=============================================================================
2608 //---------------------------StoreNode::make-----------------------------------
2609 // Polymorphic factory method:
2610 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) {
2611 assert((mo == unordered || mo == release), "unexpected");
2612 Compile* C = gvn.C;
2613 assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2614 ctl != nullptr, "raw memory operations should have control edge");
2615
2616 switch (bt) {
2617 case T_BOOLEAN: val = gvn.transform(new AndINode(val, gvn.intcon(0x1))); // Fall through to T_BYTE case
2618 case T_BYTE: return new StoreBNode(ctl, mem, adr, adr_type, val, mo);
2619 case T_INT: return new StoreINode(ctl, mem, adr, adr_type, val, mo);
2620 case T_CHAR:
2621 case T_SHORT: return new StoreCNode(ctl, mem, adr, adr_type, val, mo);
2622 case T_LONG: return new StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic_access);
2623 case T_FLOAT: return new StoreFNode(ctl, mem, adr, adr_type, val, mo);
2624 case T_DOUBLE: return new StoreDNode(ctl, mem, adr, adr_type, val, mo, require_atomic_access);
2625 case T_METADATA:
2626 case T_ADDRESS:
2627 case T_OBJECT:
2628 #ifdef _LP64
2629 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
2630 val = gvn.transform(new EncodePNode(val, val->bottom_type()->make_narrowoop()));
2631 return new StoreNNode(ctl, mem, adr, adr_type, val, mo);
2632 } else if (adr->bottom_type()->is_ptr_to_narrowklass() ||
2633 (UseCompressedClassPointers && val->bottom_type()->isa_klassptr() &&
2634 adr->bottom_type()->isa_rawptr())) {
2635 val = gvn.transform(new EncodePKlassNode(val, val->bottom_type()->make_narrowklass()));
2636 return new StoreNKlassNode(ctl, mem, adr, adr_type, val, mo);
2637 }
2638 #endif
2639 {
2640 return new StorePNode(ctl, mem, adr, adr_type, val, mo);
2641 }
2642 default:
2643 ShouldNotReachHere();
2644 return (StoreNode*)nullptr;
2645 }
2646 }
2647
2648 //--------------------------bottom_type----------------------------------------
2649 const Type *StoreNode::bottom_type() const {
2650 return Type::MEMORY;
2651 }
2652
2653 //------------------------------hash-------------------------------------------
2654 uint StoreNode::hash() const {
2655 // unroll addition of interesting fields
2656 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2657
2658 // Since they are not commoned, do not hash them:
2659 return NO_HASH;
2660 }
2661
2662 //------------------------------Ideal------------------------------------------
2663 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
2664 // When a store immediately follows a relevant allocation/initialization,
2665 // try to capture it into the initialization, or hoist it above.
2666 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2667 Node* p = MemNode::Ideal_common(phase, can_reshape);
2668 if (p) return (p == NodeSentinel) ? nullptr : p;
2669
2670 Node* mem = in(MemNode::Memory);
2671 Node* address = in(MemNode::Address);
2672 Node* value = in(MemNode::ValueIn);
2673 // Back-to-back stores to same address? Fold em up. Generally
2674 // unsafe if I have intervening uses... Also disallowed for StoreCM
2675 // since they must follow each StoreP operation. Redundant StoreCMs
2676 // are eliminated just before matching in final_graph_reshape.
2677 {
2678 Node* st = mem;
2679 // If Store 'st' has more than one use, we cannot fold 'st' away.
2680 // For example, 'st' might be the final state at a conditional
2681 // return. Or, 'st' might be used by some node which is live at
2682 // the same time 'st' is live, which might be unschedulable. So,
2683 // require exactly ONE user until such time as we clone 'mem' for
2684 // each of 'mem's uses (thus making the exactly-1-user-rule hold
2685 // true).
2686 while (st->is_Store() && st->outcnt() == 1 && st->Opcode() != Op_StoreCM) {
2687 // Looking at a dead closed cycle of memory?
2688 assert(st != st->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
2689 assert(Opcode() == st->Opcode() ||
2690 st->Opcode() == Op_StoreVector ||
2691 Opcode() == Op_StoreVector ||
2692 st->Opcode() == Op_StoreVectorScatter ||
2693 Opcode() == Op_StoreVectorScatter ||
2694 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw ||
2695 (Opcode() == Op_StoreL && st->Opcode() == Op_StoreI) || // expanded ClearArrayNode
2696 (Opcode() == Op_StoreI && st->Opcode() == Op_StoreL) || // initialization by arraycopy
2697 (is_mismatched_access() || st->as_Store()->is_mismatched_access()),
2698 "no mismatched stores, except on raw memory: %s %s", NodeClassNames[Opcode()], NodeClassNames[st->Opcode()]);
2699
2700 if (st->in(MemNode::Address)->eqv_uncast(address) &&
2701 st->as_Store()->memory_size() <= this->memory_size()) {
2702 Node* use = st->raw_out(0);
2703 if (phase->is_IterGVN()) {
2704 phase->is_IterGVN()->rehash_node_delayed(use);
2705 }
2706 // It's OK to do this in the parser, since DU info is always accurate,
2707 // and the parser always refers to nodes via SafePointNode maps.
2708 use->set_req_X(MemNode::Memory, st->in(MemNode::Memory), phase);
2709 return this;
2710 }
2711 st = st->in(MemNode::Memory);
2712 }
2713 }
2714
2715
2716 // Capture an unaliased, unconditional, simple store into an initializer.
2717 // Or, if it is independent of the allocation, hoist it above the allocation.
2718 if (ReduceFieldZeroing && /*can_reshape &&*/
2719 mem->is_Proj() && mem->in(0)->is_Initialize()) {
2720 InitializeNode* init = mem->in(0)->as_Initialize();
2721 intptr_t offset = init->can_capture_store(this, phase, can_reshape);
2722 if (offset > 0) {
2723 Node* moved = init->capture_store(this, offset, phase, can_reshape);
2724 // If the InitializeNode captured me, it made a raw copy of me,
2725 // and I need to disappear.
2726 if (moved != nullptr) {
2727 // %%% hack to ensure that Ideal returns a new node:
2728 mem = MergeMemNode::make(mem);
2729 return mem; // fold me away
2730 }
2731 }
2732 }
2733
2734 // Fold reinterpret cast into memory operation:
2735 // StoreX mem (MoveY2X v) => StoreY mem v
2736 if (value->is_Move()) {
2737 const Type* vt = value->in(1)->bottom_type();
2738 if (has_reinterpret_variant(vt)) {
2739 if (phase->C->post_loop_opts_phase()) {
2740 return convert_to_reinterpret_store(*phase, value->in(1), vt);
2741 } else {
2742 phase->C->record_for_post_loop_opts_igvn(this); // attempt the transformation once loop opts are over
2743 }
2744 }
2745 }
2746
2747 return nullptr; // No further progress
2748 }
2749
2750 //------------------------------Value-----------------------------------------
2751 const Type* StoreNode::Value(PhaseGVN* phase) const {
2752 // Either input is TOP ==> the result is TOP
2753 const Type *t1 = phase->type( in(MemNode::Memory) );
2754 if( t1 == Type::TOP ) return Type::TOP;
2755 const Type *t2 = phase->type( in(MemNode::Address) );
2756 if( t2 == Type::TOP ) return Type::TOP;
2757 const Type *t3 = phase->type( in(MemNode::ValueIn) );
2758 if( t3 == Type::TOP ) return Type::TOP;
2759 return Type::MEMORY;
2760 }
2761
2762 //------------------------------Identity---------------------------------------
2763 // Remove redundant stores:
2764 // Store(m, p, Load(m, p)) changes to m.
2765 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
2766 Node* StoreNode::Identity(PhaseGVN* phase) {
2767 Node* mem = in(MemNode::Memory);
2768 Node* adr = in(MemNode::Address);
2769 Node* val = in(MemNode::ValueIn);
2770
2771 Node* result = this;
2772
2773 // Load then Store? Then the Store is useless
2774 if (val->is_Load() &&
2775 val->in(MemNode::Address)->eqv_uncast(adr) &&
2776 val->in(MemNode::Memory )->eqv_uncast(mem) &&
2777 val->as_Load()->store_Opcode() == Opcode()) {
2778 result = mem;
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 result = mem;
2788 }
2789
2790 // Store of zero anywhere into a freshly-allocated object?
2791 // Then the store is useless.
2792 // (It must already have been captured by the InitializeNode.)
2793 if (result == this &&
2794 ReduceFieldZeroing && phase->type(val)->is_zero_type()) {
2795 // a newly allocated object is already all-zeroes everywhere
2796 if (mem->is_Proj() && mem->in(0)->is_Allocate()) {
2797 result = mem;
2798 }
2799
2800 if (result == this) {
2801 // the store may also apply to zero-bits in an earlier object
2802 Node* prev_mem = find_previous_store(phase);
2803 // Steps (a), (b): Walk past independent stores to find an exact match.
2804 if (prev_mem != nullptr) {
2805 Node* prev_val = can_see_stored_value(prev_mem, phase);
2806 if (prev_val != nullptr && prev_val == val) {
2807 // prev_val and val might differ by a cast; it would be good
2808 // to keep the more informative of the two.
2809 result = mem;
2810 }
2811 }
2812 }
2813 }
2814
2815 PhaseIterGVN* igvn = phase->is_IterGVN();
2816 if (result != this && igvn != nullptr) {
2817 MemBarNode* trailing = trailing_membar();
2818 if (trailing != nullptr) {
2819 #ifdef ASSERT
2820 const TypeOopPtr* t_oop = phase->type(in(Address))->isa_oopptr();
2821 assert(t_oop == nullptr || t_oop->is_known_instance_field(), "only for non escaping objects");
2822 #endif
2823 trailing->remove(igvn);
2824 }
2825 }
2826
2827 return result;
2828 }
2829
2830 //------------------------------match_edge-------------------------------------
2831 // Do we Match on this edge index or not? Match only memory & value
2832 uint StoreNode::match_edge(uint idx) const {
2833 return idx == MemNode::Address || idx == MemNode::ValueIn;
2834 }
2835
2836 //------------------------------cmp--------------------------------------------
2837 // Do not common stores up together. They generally have to be split
2838 // back up anyways, so do not bother.
2839 bool StoreNode::cmp( const Node &n ) const {
2840 return (&n == this); // Always fail except on self
2841 }
2842
2843 //------------------------------Ideal_masked_input-----------------------------
2844 // Check for a useless mask before a partial-word store
2845 // (StoreB ... (AndI valIn conIa) )
2846 // If (conIa & mask == mask) this simplifies to
2847 // (StoreB ... (valIn) )
2848 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
2849 Node *val = in(MemNode::ValueIn);
2850 if( val->Opcode() == Op_AndI ) {
2851 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2852 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
2853 set_req_X(MemNode::ValueIn, val->in(1), phase);
2854 return this;
2855 }
2856 }
2857 return nullptr;
2858 }
2859
2860
2861 //------------------------------Ideal_sign_extended_input----------------------
2862 // Check for useless sign-extension before a partial-word store
2863 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) )
2864 // If (conIL == conIR && conIR <= num_bits) this simplifies to
2865 // (StoreB ... (valIn) )
2866 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) {
2867 Node *val = in(MemNode::ValueIn);
2868 if( val->Opcode() == Op_RShiftI ) {
2869 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2870 if( t && t->is_con() && (t->get_con() <= num_bits) ) {
2871 Node *shl = val->in(1);
2872 if( shl->Opcode() == Op_LShiftI ) {
2873 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int();
2874 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) {
2875 set_req_X(MemNode::ValueIn, shl->in(1), phase);
2876 return this;
2877 }
2878 }
2879 }
2880 }
2881 return nullptr;
2882 }
2883
2884 //------------------------------value_never_loaded-----------------------------------
2885 // Determine whether there are any possible loads of the value stored.
2886 // For simplicity, we actually check if there are any loads from the
2887 // address stored to, not just for loads of the value stored by this node.
2888 //
2889 bool StoreNode::value_never_loaded(PhaseValues* phase) const {
2890 Node *adr = in(Address);
2891 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
2892 if (adr_oop == nullptr)
2893 return false;
2894 if (!adr_oop->is_known_instance_field())
2895 return false; // if not a distinct instance, there may be aliases of the address
2896 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
2897 Node *use = adr->fast_out(i);
2898 if (use->is_Load() || use->is_LoadStore()) {
2899 return false;
2900 }
2901 }
2902 return true;
2903 }
2904
2905 MemBarNode* StoreNode::trailing_membar() const {
2906 if (is_release()) {
2907 MemBarNode* trailing_mb = nullptr;
2908 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
2909 Node* u = fast_out(i);
2910 if (u->is_MemBar()) {
2911 if (u->as_MemBar()->trailing_store()) {
2912 assert(u->Opcode() == Op_MemBarVolatile, "");
2913 assert(trailing_mb == nullptr, "only one");
2914 trailing_mb = u->as_MemBar();
2915 #ifdef ASSERT
2916 Node* leading = u->as_MemBar()->leading_membar();
2917 assert(leading->Opcode() == Op_MemBarRelease, "incorrect membar");
2918 assert(leading->as_MemBar()->leading_store(), "incorrect membar pair");
2919 assert(leading->as_MemBar()->trailing_membar() == u, "incorrect membar pair");
2920 #endif
2921 } else {
2922 assert(u->as_MemBar()->standalone(), "");
2923 }
2924 }
2925 }
2926 return trailing_mb;
2927 }
2928 return nullptr;
2929 }
2930
2931
2932 //=============================================================================
2933 //------------------------------Ideal------------------------------------------
2934 // If the store is from an AND mask that leaves the low bits untouched, then
2935 // we can skip the AND operation. If the store is from a sign-extension
2936 // (a left shift, then right shift) we can skip both.
2937 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
2938 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
2939 if( progress != nullptr ) return progress;
2940
2941 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
2942 if( progress != nullptr ) return progress;
2943
2944 // Finally check the default case
2945 return StoreNode::Ideal(phase, can_reshape);
2946 }
2947
2948 //=============================================================================
2949 //------------------------------Ideal------------------------------------------
2950 // If the store is from an AND mask that leaves the low bits untouched, then
2951 // we can skip the AND operation
2952 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
2953 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
2954 if( progress != nullptr ) return progress;
2955
2956 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
2957 if( progress != nullptr ) return progress;
2958
2959 // Finally check the default case
2960 return StoreNode::Ideal(phase, can_reshape);
2961 }
2962
2963 //=============================================================================
2964 //------------------------------Identity---------------------------------------
2965 Node* StoreCMNode::Identity(PhaseGVN* phase) {
2966 // No need to card mark when storing a null ptr
2967 Node* my_store = in(MemNode::OopStore);
2968 if (my_store->is_Store()) {
2969 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) );
2970 if( t1 == TypePtr::NULL_PTR ) {
2971 return in(MemNode::Memory);
2972 }
2973 }
2974 return this;
2975 }
2976
2977 //=============================================================================
2978 //------------------------------Ideal---------------------------------------
2979 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){
2980 Node* progress = StoreNode::Ideal(phase, can_reshape);
2981 if (progress != nullptr) return progress;
2982
2983 Node* my_store = in(MemNode::OopStore);
2984 if (my_store->is_MergeMem()) {
2985 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx());
2986 set_req_X(MemNode::OopStore, mem, phase);
2987 return this;
2988 }
2989
2990 return nullptr;
2991 }
2992
2993 //------------------------------Value-----------------------------------------
2994 const Type* StoreCMNode::Value(PhaseGVN* phase) const {
2995 // Either input is TOP ==> the result is TOP (checked in StoreNode::Value).
2996 // If extra input is TOP ==> the result is TOP
2997 const Type* t = phase->type(in(MemNode::OopStore));
2998 if (t == Type::TOP) {
2999 return Type::TOP;
3000 }
3001 return StoreNode::Value(phase);
3002 }
3003
3004
3005 //=============================================================================
3006 //----------------------------------SCMemProjNode------------------------------
3007 const Type* SCMemProjNode::Value(PhaseGVN* phase) const
3008 {
3009 if (in(0) == nullptr || phase->type(in(0)) == Type::TOP) {
3010 return Type::TOP;
3011 }
3012 return bottom_type();
3013 }
3014
3015 //=============================================================================
3016 //----------------------------------LoadStoreNode------------------------------
3017 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required )
3018 : Node(required),
3019 _type(rt),
3020 _adr_type(at),
3021 _barrier_data(0)
3022 {
3023 init_req(MemNode::Control, c );
3024 init_req(MemNode::Memory , mem);
3025 init_req(MemNode::Address, adr);
3026 init_req(MemNode::ValueIn, val);
3027 init_class_id(Class_LoadStore);
3028 }
3029
3030 //------------------------------Value-----------------------------------------
3031 const Type* LoadStoreNode::Value(PhaseGVN* phase) const {
3032 // Either input is TOP ==> the result is TOP
3033 if (!in(MemNode::Control) || phase->type(in(MemNode::Control)) == Type::TOP) {
3034 return Type::TOP;
3035 }
3036 const Type* t = phase->type(in(MemNode::Memory));
3037 if (t == Type::TOP) {
3038 return Type::TOP;
3039 }
3040 t = phase->type(in(MemNode::Address));
3041 if (t == Type::TOP) {
3042 return Type::TOP;
3043 }
3044 t = phase->type(in(MemNode::ValueIn));
3045 if (t == Type::TOP) {
3046 return Type::TOP;
3047 }
3048 return bottom_type();
3049 }
3050
3051 uint LoadStoreNode::ideal_reg() const {
3052 return _type->ideal_reg();
3053 }
3054
3055 // This method conservatively checks if the result of a LoadStoreNode is
3056 // used, that is, if it returns true, then it is definitely the case that
3057 // the result of the node is not needed.
3058 // For example, GetAndAdd can be matched into a lock_add instead of a
3059 // lock_xadd if the result of LoadStoreNode::result_not_used() is true
3060 bool LoadStoreNode::result_not_used() const {
3061 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
3062 Node *x = fast_out(i);
3063 if (x->Opcode() == Op_SCMemProj) {
3064 continue;
3065 }
3066 if (x->bottom_type() == TypeTuple::MEMBAR &&
3067 !x->is_Call() &&
3068 x->Opcode() != Op_Blackhole) {
3069 continue;
3070 }
3071 return false;
3072 }
3073 return true;
3074 }
3075
3076 MemBarNode* LoadStoreNode::trailing_membar() const {
3077 MemBarNode* trailing = nullptr;
3078 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
3079 Node* u = fast_out(i);
3080 if (u->is_MemBar()) {
3081 if (u->as_MemBar()->trailing_load_store()) {
3082 assert(u->Opcode() == Op_MemBarAcquire, "");
3083 assert(trailing == nullptr, "only one");
3084 trailing = u->as_MemBar();
3085 #ifdef ASSERT
3086 Node* leading = trailing->leading_membar();
3087 assert(support_IRIW_for_not_multiple_copy_atomic_cpu || leading->Opcode() == Op_MemBarRelease, "incorrect membar");
3088 assert(leading->as_MemBar()->leading_load_store(), "incorrect membar pair");
3089 assert(leading->as_MemBar()->trailing_membar() == trailing, "incorrect membar pair");
3090 #endif
3091 } else {
3092 assert(u->as_MemBar()->standalone(), "wrong barrier kind");
3093 }
3094 }
3095 }
3096
3097 return trailing;
3098 }
3099
3100 uint LoadStoreNode::size_of() const { return sizeof(*this); }
3101
3102 //=============================================================================
3103 //----------------------------------LoadStoreConditionalNode--------------------
3104 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, nullptr, TypeInt::BOOL, 5) {
3105 init_req(ExpectedIn, ex );
3106 }
3107
3108 const Type* LoadStoreConditionalNode::Value(PhaseGVN* phase) const {
3109 // Either input is TOP ==> the result is TOP
3110 const Type* t = phase->type(in(ExpectedIn));
3111 if (t == Type::TOP) {
3112 return Type::TOP;
3113 }
3114 return LoadStoreNode::Value(phase);
3115 }
3116
3117 //=============================================================================
3118 //-------------------------------adr_type--------------------------------------
3119 const TypePtr* ClearArrayNode::adr_type() const {
3120 Node *adr = in(3);
3121 if (adr == nullptr) return nullptr; // node is dead
3122 return MemNode::calculate_adr_type(adr->bottom_type());
3123 }
3124
3125 //------------------------------match_edge-------------------------------------
3126 // Do we Match on this edge index or not? Do not match memory
3127 uint ClearArrayNode::match_edge(uint idx) const {
3128 return idx > 1;
3129 }
3130
3131 //------------------------------Identity---------------------------------------
3132 // Clearing a zero length array does nothing
3133 Node* ClearArrayNode::Identity(PhaseGVN* phase) {
3134 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
3135 }
3136
3137 //------------------------------Idealize---------------------------------------
3138 // Clearing a short array is faster with stores
3139 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3140 // Already know this is a large node, do not try to ideal it
3141 if (_is_large) return nullptr;
3142
3143 const int unit = BytesPerLong;
3144 const TypeX* t = phase->type(in(2))->isa_intptr_t();
3145 if (!t) return nullptr;
3146 if (!t->is_con()) return nullptr;
3147 intptr_t raw_count = t->get_con();
3148 intptr_t size = raw_count;
3149 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
3150 // Clearing nothing uses the Identity call.
3151 // Negative clears are possible on dead ClearArrays
3152 // (see jck test stmt114.stmt11402.val).
3153 if (size <= 0 || size % unit != 0) return nullptr;
3154 intptr_t count = size / unit;
3155 // Length too long; communicate this to matchers and assemblers.
3156 // Assemblers are responsible to produce fast hardware clears for it.
3157 if (size > InitArrayShortSize) {
3158 return new ClearArrayNode(in(0), in(1), in(2), in(3), true);
3159 } else if (size > 2 && Matcher::match_rule_supported_vector(Op_ClearArray, 4, T_LONG)) {
3160 return nullptr;
3161 }
3162 if (!IdealizeClearArrayNode) return nullptr;
3163 Node *mem = in(1);
3164 if( phase->type(mem)==Type::TOP ) return nullptr;
3165 Node *adr = in(3);
3166 const Type* at = phase->type(adr);
3167 if( at==Type::TOP ) return nullptr;
3168 const TypePtr* atp = at->isa_ptr();
3169 // adjust atp to be the correct array element address type
3170 if (atp == nullptr) atp = TypePtr::BOTTOM;
3171 else atp = atp->add_offset(Type::OffsetBot);
3172 // Get base for derived pointer purposes
3173 if( adr->Opcode() != Op_AddP ) Unimplemented();
3174 Node *base = adr->in(1);
3175
3176 Node *zero = phase->makecon(TypeLong::ZERO);
3177 Node *off = phase->MakeConX(BytesPerLong);
3178 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
3179 count--;
3180 while( count-- ) {
3181 mem = phase->transform(mem);
3182 adr = phase->transform(new AddPNode(base,adr,off));
3183 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
3184 }
3185 return mem;
3186 }
3187
3188 //----------------------------step_through----------------------------------
3189 // Return allocation input memory edge if it is different instance
3190 // or itself if it is the one we are looking for.
3191 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseValues* phase) {
3192 Node* n = *np;
3193 assert(n->is_ClearArray(), "sanity");
3194 intptr_t offset;
3195 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
3196 // This method is called only before Allocate nodes are expanded
3197 // during macro nodes expansion. Before that ClearArray nodes are
3198 // only generated in PhaseMacroExpand::generate_arraycopy() (before
3199 // Allocate nodes are expanded) which follows allocations.
3200 assert(alloc != nullptr, "should have allocation");
3201 if (alloc->_idx == instance_id) {
3202 // Can not bypass initialization of the instance we are looking for.
3203 return false;
3204 }
3205 // Otherwise skip it.
3206 InitializeNode* init = alloc->initialization();
3207 if (init != nullptr)
3208 *np = init->in(TypeFunc::Memory);
3209 else
3210 *np = alloc->in(TypeFunc::Memory);
3211 return true;
3212 }
3213
3214 //----------------------------clear_memory-------------------------------------
3215 // Generate code to initialize object storage to zero.
3216 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
3217 intptr_t start_offset,
3218 Node* end_offset,
3219 PhaseGVN* phase) {
3220 intptr_t offset = start_offset;
3221
3222 int unit = BytesPerLong;
3223 if ((offset % unit) != 0) {
3224 Node* adr = new AddPNode(dest, dest, phase->MakeConX(offset));
3225 adr = phase->transform(adr);
3226 const TypePtr* atp = TypeRawPtr::BOTTOM;
3227 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
3228 mem = phase->transform(mem);
3229 offset += BytesPerInt;
3230 }
3231 assert((offset % unit) == 0, "");
3232
3233 // Initialize the remaining stuff, if any, with a ClearArray.
3234 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase);
3235 }
3236
3237 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
3238 Node* start_offset,
3239 Node* end_offset,
3240 PhaseGVN* phase) {
3241 if (start_offset == end_offset) {
3242 // nothing to do
3243 return mem;
3244 }
3245
3246 int unit = BytesPerLong;
3247 Node* zbase = start_offset;
3248 Node* zend = end_offset;
3249
3250 // Scale to the unit required by the CPU:
3251 if (!Matcher::init_array_count_is_in_bytes) {
3252 Node* shift = phase->intcon(exact_log2(unit));
3253 zbase = phase->transform(new URShiftXNode(zbase, shift) );
3254 zend = phase->transform(new URShiftXNode(zend, shift) );
3255 }
3256
3257 // Bulk clear double-words
3258 Node* zsize = phase->transform(new SubXNode(zend, zbase) );
3259 Node* adr = phase->transform(new AddPNode(dest, dest, start_offset) );
3260 mem = new ClearArrayNode(ctl, mem, zsize, adr, false);
3261 return phase->transform(mem);
3262 }
3263
3264 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
3265 intptr_t start_offset,
3266 intptr_t end_offset,
3267 PhaseGVN* phase) {
3268 if (start_offset == end_offset) {
3269 // nothing to do
3270 return mem;
3271 }
3272
3273 assert((end_offset % BytesPerInt) == 0, "odd end offset");
3274 intptr_t done_offset = end_offset;
3275 if ((done_offset % BytesPerLong) != 0) {
3276 done_offset -= BytesPerInt;
3277 }
3278 if (done_offset > start_offset) {
3279 mem = clear_memory(ctl, mem, dest,
3280 start_offset, phase->MakeConX(done_offset), phase);
3281 }
3282 if (done_offset < end_offset) { // emit the final 32-bit store
3283 Node* adr = new AddPNode(dest, dest, phase->MakeConX(done_offset));
3284 adr = phase->transform(adr);
3285 const TypePtr* atp = TypeRawPtr::BOTTOM;
3286 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
3287 mem = phase->transform(mem);
3288 done_offset += BytesPerInt;
3289 }
3290 assert(done_offset == end_offset, "");
3291 return mem;
3292 }
3293
3294 //=============================================================================
3295 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
3296 : MultiNode(TypeFunc::Parms + (precedent == nullptr? 0: 1)),
3297 _adr_type(C->get_adr_type(alias_idx)), _kind(Standalone)
3298 #ifdef ASSERT
3299 , _pair_idx(0)
3300 #endif
3301 {
3302 init_class_id(Class_MemBar);
3303 Node* top = C->top();
3304 init_req(TypeFunc::I_O,top);
3305 init_req(TypeFunc::FramePtr,top);
3306 init_req(TypeFunc::ReturnAdr,top);
3307 if (precedent != nullptr)
3308 init_req(TypeFunc::Parms, precedent);
3309 }
3310
3311 //------------------------------cmp--------------------------------------------
3312 uint MemBarNode::hash() const { return NO_HASH; }
3313 bool MemBarNode::cmp( const Node &n ) const {
3314 return (&n == this); // Always fail except on self
3315 }
3316
3317 //------------------------------make-------------------------------------------
3318 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
3319 switch (opcode) {
3320 case Op_MemBarAcquire: return new MemBarAcquireNode(C, atp, pn);
3321 case Op_LoadFence: return new LoadFenceNode(C, atp, pn);
3322 case Op_MemBarRelease: return new MemBarReleaseNode(C, atp, pn);
3323 case Op_StoreFence: return new StoreFenceNode(C, atp, pn);
3324 case Op_MemBarStoreStore: return new MemBarStoreStoreNode(C, atp, pn);
3325 case Op_StoreStoreFence: return new StoreStoreFenceNode(C, atp, pn);
3326 case Op_MemBarAcquireLock: return new MemBarAcquireLockNode(C, atp, pn);
3327 case Op_MemBarReleaseLock: return new MemBarReleaseLockNode(C, atp, pn);
3328 case Op_MemBarVolatile: return new MemBarVolatileNode(C, atp, pn);
3329 case Op_MemBarCPUOrder: return new MemBarCPUOrderNode(C, atp, pn);
3330 case Op_OnSpinWait: return new OnSpinWaitNode(C, atp, pn);
3331 case Op_Initialize: return new InitializeNode(C, atp, pn);
3332 default: ShouldNotReachHere(); return nullptr;
3333 }
3334 }
3335
3336 void MemBarNode::remove(PhaseIterGVN *igvn) {
3337 if (outcnt() != 2) {
3338 assert(Opcode() == Op_Initialize, "Only seen when there are no use of init memory");
3339 assert(outcnt() == 1, "Only control then");
3340 }
3341 if (trailing_store() || trailing_load_store()) {
3342 MemBarNode* leading = leading_membar();
3343 if (leading != nullptr) {
3344 assert(leading->trailing_membar() == this, "inconsistent leading/trailing membars");
3345 leading->remove(igvn);
3346 }
3347 }
3348 if (proj_out_or_null(TypeFunc::Memory) != nullptr) {
3349 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
3350 }
3351 if (proj_out_or_null(TypeFunc::Control) != nullptr) {
3352 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
3353 }
3354 }
3355
3356 //------------------------------Ideal------------------------------------------
3357 // Return a node which is more "ideal" than the current node. Strip out
3358 // control copies
3359 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3360 if (remove_dead_region(phase, can_reshape)) return this;
3361 // Don't bother trying to transform a dead node
3362 if (in(0) && in(0)->is_top()) {
3363 return nullptr;
3364 }
3365
3366 bool progress = false;
3367 // Eliminate volatile MemBars for scalar replaced objects.
3368 if (can_reshape && req() == (Precedent+1)) {
3369 bool eliminate = false;
3370 int opc = Opcode();
3371 if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) {
3372 // Volatile field loads and stores.
3373 Node* my_mem = in(MemBarNode::Precedent);
3374 // The MembarAquire may keep an unused LoadNode alive through the Precedent edge
3375 if ((my_mem != nullptr) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) {
3376 // if the Precedent is a decodeN and its input (a Load) is used at more than one place,
3377 // replace this Precedent (decodeN) with the Load instead.
3378 if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1)) {
3379 Node* load_node = my_mem->in(1);
3380 set_req(MemBarNode::Precedent, load_node);
3381 phase->is_IterGVN()->_worklist.push(my_mem);
3382 my_mem = load_node;
3383 } else {
3384 assert(my_mem->unique_out() == this, "sanity");
3385 del_req(Precedent);
3386 phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later
3387 my_mem = nullptr;
3388 }
3389 progress = true;
3390 }
3391 if (my_mem != nullptr && my_mem->is_Mem()) {
3392 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
3393 // Check for scalar replaced object reference.
3394 if( t_oop != nullptr && t_oop->is_known_instance_field() &&
3395 t_oop->offset() != Type::OffsetBot &&
3396 t_oop->offset() != Type::OffsetTop) {
3397 eliminate = true;
3398 }
3399 }
3400 } else if (opc == Op_MemBarRelease) {
3401 // Final field stores.
3402 Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent));
3403 if ((alloc != nullptr) && alloc->is_Allocate() &&
3404 alloc->as_Allocate()->does_not_escape_thread()) {
3405 // The allocated object does not escape.
3406 eliminate = true;
3407 }
3408 }
3409 if (eliminate) {
3410 // Replace MemBar projections by its inputs.
3411 PhaseIterGVN* igvn = phase->is_IterGVN();
3412 remove(igvn);
3413 // Must return either the original node (now dead) or a new node
3414 // (Do not return a top here, since that would break the uniqueness of top.)
3415 return new ConINode(TypeInt::ZERO);
3416 }
3417 }
3418 return progress ? this : nullptr;
3419 }
3420
3421 //------------------------------Value------------------------------------------
3422 const Type* MemBarNode::Value(PhaseGVN* phase) const {
3423 if( !in(0) ) return Type::TOP;
3424 if( phase->type(in(0)) == Type::TOP )
3425 return Type::TOP;
3426 return TypeTuple::MEMBAR;
3427 }
3428
3429 //------------------------------match------------------------------------------
3430 // Construct projections for memory.
3431 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) {
3432 switch (proj->_con) {
3433 case TypeFunc::Control:
3434 case TypeFunc::Memory:
3435 return new MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
3436 }
3437 ShouldNotReachHere();
3438 return nullptr;
3439 }
3440
3441 void MemBarNode::set_store_pair(MemBarNode* leading, MemBarNode* trailing) {
3442 trailing->_kind = TrailingStore;
3443 leading->_kind = LeadingStore;
3444 #ifdef ASSERT
3445 trailing->_pair_idx = leading->_idx;
3446 leading->_pair_idx = leading->_idx;
3447 #endif
3448 }
3449
3450 void MemBarNode::set_load_store_pair(MemBarNode* leading, MemBarNode* trailing) {
3451 trailing->_kind = TrailingLoadStore;
3452 leading->_kind = LeadingLoadStore;
3453 #ifdef ASSERT
3454 trailing->_pair_idx = leading->_idx;
3455 leading->_pair_idx = leading->_idx;
3456 #endif
3457 }
3458
3459 MemBarNode* MemBarNode::trailing_membar() const {
3460 ResourceMark rm;
3461 Node* trailing = (Node*)this;
3462 VectorSet seen;
3463 Node_Stack multis(0);
3464 do {
3465 Node* c = trailing;
3466 uint i = 0;
3467 do {
3468 trailing = nullptr;
3469 for (; i < c->outcnt(); i++) {
3470 Node* next = c->raw_out(i);
3471 if (next != c && next->is_CFG()) {
3472 if (c->is_MultiBranch()) {
3473 if (multis.node() == c) {
3474 multis.set_index(i+1);
3475 } else {
3476 multis.push(c, i+1);
3477 }
3478 }
3479 trailing = next;
3480 break;
3481 }
3482 }
3483 if (trailing != nullptr && !seen.test_set(trailing->_idx)) {
3484 break;
3485 }
3486 while (multis.size() > 0) {
3487 c = multis.node();
3488 i = multis.index();
3489 if (i < c->req()) {
3490 break;
3491 }
3492 multis.pop();
3493 }
3494 } while (multis.size() > 0);
3495 } while (!trailing->is_MemBar() || !trailing->as_MemBar()->trailing());
3496
3497 MemBarNode* mb = trailing->as_MemBar();
3498 assert((mb->_kind == TrailingStore && _kind == LeadingStore) ||
3499 (mb->_kind == TrailingLoadStore && _kind == LeadingLoadStore), "bad trailing membar");
3500 assert(mb->_pair_idx == _pair_idx, "bad trailing membar");
3501 return mb;
3502 }
3503
3504 MemBarNode* MemBarNode::leading_membar() const {
3505 ResourceMark rm;
3506 VectorSet seen;
3507 Node_Stack regions(0);
3508 Node* leading = in(0);
3509 while (leading != nullptr && (!leading->is_MemBar() || !leading->as_MemBar()->leading())) {
3510 while (leading == nullptr || leading->is_top() || seen.test_set(leading->_idx)) {
3511 leading = nullptr;
3512 while (regions.size() > 0 && leading == nullptr) {
3513 Node* r = regions.node();
3514 uint i = regions.index();
3515 if (i < r->req()) {
3516 leading = r->in(i);
3517 regions.set_index(i+1);
3518 } else {
3519 regions.pop();
3520 }
3521 }
3522 if (leading == nullptr) {
3523 assert(regions.size() == 0, "all paths should have been tried");
3524 return nullptr;
3525 }
3526 }
3527 if (leading->is_Region()) {
3528 regions.push(leading, 2);
3529 leading = leading->in(1);
3530 } else {
3531 leading = leading->in(0);
3532 }
3533 }
3534 #ifdef ASSERT
3535 Unique_Node_List wq;
3536 wq.push((Node*)this);
3537 uint found = 0;
3538 for (uint i = 0; i < wq.size(); i++) {
3539 Node* n = wq.at(i);
3540 if (n->is_Region()) {
3541 for (uint j = 1; j < n->req(); j++) {
3542 Node* in = n->in(j);
3543 if (in != nullptr && !in->is_top()) {
3544 wq.push(in);
3545 }
3546 }
3547 } else {
3548 if (n->is_MemBar() && n->as_MemBar()->leading()) {
3549 assert(n == leading, "consistency check failed");
3550 found++;
3551 } else {
3552 Node* in = n->in(0);
3553 if (in != nullptr && !in->is_top()) {
3554 wq.push(in);
3555 }
3556 }
3557 }
3558 }
3559 assert(found == 1 || (found == 0 && leading == nullptr), "consistency check failed");
3560 #endif
3561 if (leading == nullptr) {
3562 return nullptr;
3563 }
3564 MemBarNode* mb = leading->as_MemBar();
3565 assert((mb->_kind == LeadingStore && _kind == TrailingStore) ||
3566 (mb->_kind == LeadingLoadStore && _kind == TrailingLoadStore), "bad leading membar");
3567 assert(mb->_pair_idx == _pair_idx, "bad leading membar");
3568 return mb;
3569 }
3570
3571
3572 //===========================InitializeNode====================================
3573 // SUMMARY:
3574 // This node acts as a memory barrier on raw memory, after some raw stores.
3575 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
3576 // The Initialize can 'capture' suitably constrained stores as raw inits.
3577 // It can coalesce related raw stores into larger units (called 'tiles').
3578 // It can avoid zeroing new storage for memory units which have raw inits.
3579 // At macro-expansion, it is marked 'complete', and does not optimize further.
3580 //
3581 // EXAMPLE:
3582 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
3583 // ctl = incoming control; mem* = incoming memory
3584 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
3585 // First allocate uninitialized memory and fill in the header:
3586 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
3587 // ctl := alloc.Control; mem* := alloc.Memory*
3588 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
3589 // Then initialize to zero the non-header parts of the raw memory block:
3590 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
3591 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
3592 // After the initialize node executes, the object is ready for service:
3593 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
3594 // Suppose its body is immediately initialized as {1,2}:
3595 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3596 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3597 // mem.SLICE(#short[*]) := store2
3598 //
3599 // DETAILS:
3600 // An InitializeNode collects and isolates object initialization after
3601 // an AllocateNode and before the next possible safepoint. As a
3602 // memory barrier (MemBarNode), it keeps critical stores from drifting
3603 // down past any safepoint or any publication of the allocation.
3604 // Before this barrier, a newly-allocated object may have uninitialized bits.
3605 // After this barrier, it may be treated as a real oop, and GC is allowed.
3606 //
3607 // The semantics of the InitializeNode include an implicit zeroing of
3608 // the new object from object header to the end of the object.
3609 // (The object header and end are determined by the AllocateNode.)
3610 //
3611 // Certain stores may be added as direct inputs to the InitializeNode.
3612 // These stores must update raw memory, and they must be to addresses
3613 // derived from the raw address produced by AllocateNode, and with
3614 // a constant offset. They must be ordered by increasing offset.
3615 // The first one is at in(RawStores), the last at in(req()-1).
3616 // Unlike most memory operations, they are not linked in a chain,
3617 // but are displayed in parallel as users of the rawmem output of
3618 // the allocation.
3619 //
3620 // (See comments in InitializeNode::capture_store, which continue
3621 // the example given above.)
3622 //
3623 // When the associated Allocate is macro-expanded, the InitializeNode
3624 // may be rewritten to optimize collected stores. A ClearArrayNode
3625 // may also be created at that point to represent any required zeroing.
3626 // The InitializeNode is then marked 'complete', prohibiting further
3627 // capturing of nearby memory operations.
3628 //
3629 // During macro-expansion, all captured initializations which store
3630 // constant values of 32 bits or smaller are coalesced (if advantageous)
3631 // into larger 'tiles' 32 or 64 bits. This allows an object to be
3632 // initialized in fewer memory operations. Memory words which are
3633 // covered by neither tiles nor non-constant stores are pre-zeroed
3634 // by explicit stores of zero. (The code shape happens to do all
3635 // zeroing first, then all other stores, with both sequences occurring
3636 // in order of ascending offsets.)
3637 //
3638 // Alternatively, code may be inserted between an AllocateNode and its
3639 // InitializeNode, to perform arbitrary initialization of the new object.
3640 // E.g., the object copying intrinsics insert complex data transfers here.
3641 // The initialization must then be marked as 'complete' disable the
3642 // built-in zeroing semantics and the collection of initializing stores.
3643 //
3644 // While an InitializeNode is incomplete, reads from the memory state
3645 // produced by it are optimizable if they match the control edge and
3646 // new oop address associated with the allocation/initialization.
3647 // They return a stored value (if the offset matches) or else zero.
3648 // A write to the memory state, if it matches control and address,
3649 // and if it is to a constant offset, may be 'captured' by the
3650 // InitializeNode. It is cloned as a raw memory operation and rewired
3651 // inside the initialization, to the raw oop produced by the allocation.
3652 // Operations on addresses which are provably distinct (e.g., to
3653 // other AllocateNodes) are allowed to bypass the initialization.
3654 //
3655 // The effect of all this is to consolidate object initialization
3656 // (both arrays and non-arrays, both piecewise and bulk) into a
3657 // single location, where it can be optimized as a unit.
3658 //
3659 // Only stores with an offset less than TrackedInitializationLimit words
3660 // will be considered for capture by an InitializeNode. This puts a
3661 // reasonable limit on the complexity of optimized initializations.
3662
3663 //---------------------------InitializeNode------------------------------------
3664 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
3665 : MemBarNode(C, adr_type, rawoop),
3666 _is_complete(Incomplete), _does_not_escape(false)
3667 {
3668 init_class_id(Class_Initialize);
3669
3670 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
3671 assert(in(RawAddress) == rawoop, "proper init");
3672 // Note: allocation() can be null, for secondary initialization barriers
3673 }
3674
3675 // Since this node is not matched, it will be processed by the
3676 // register allocator. Declare that there are no constraints
3677 // on the allocation of the RawAddress edge.
3678 const RegMask &InitializeNode::in_RegMask(uint idx) const {
3679 // This edge should be set to top, by the set_complete. But be conservative.
3680 if (idx == InitializeNode::RawAddress)
3681 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
3682 return RegMask::Empty;
3683 }
3684
3685 Node* InitializeNode::memory(uint alias_idx) {
3686 Node* mem = in(Memory);
3687 if (mem->is_MergeMem()) {
3688 return mem->as_MergeMem()->memory_at(alias_idx);
3689 } else {
3690 // incoming raw memory is not split
3691 return mem;
3692 }
3693 }
3694
3695 bool InitializeNode::is_non_zero() {
3696 if (is_complete()) return false;
3697 remove_extra_zeroes();
3698 return (req() > RawStores);
3699 }
3700
3701 void InitializeNode::set_complete(PhaseGVN* phase) {
3702 assert(!is_complete(), "caller responsibility");
3703 _is_complete = Complete;
3704
3705 // After this node is complete, it contains a bunch of
3706 // raw-memory initializations. There is no need for
3707 // it to have anything to do with non-raw memory effects.
3708 // Therefore, tell all non-raw users to re-optimize themselves,
3709 // after skipping the memory effects of this initialization.
3710 PhaseIterGVN* igvn = phase->is_IterGVN();
3711 if (igvn) igvn->add_users_to_worklist(this);
3712 }
3713
3714 // convenience function
3715 // return false if the init contains any stores already
3716 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
3717 InitializeNode* init = initialization();
3718 if (init == nullptr || init->is_complete()) return false;
3719 init->remove_extra_zeroes();
3720 // for now, if this allocation has already collected any inits, bail:
3721 if (init->is_non_zero()) return false;
3722 init->set_complete(phase);
3723 return true;
3724 }
3725
3726 void InitializeNode::remove_extra_zeroes() {
3727 if (req() == RawStores) return;
3728 Node* zmem = zero_memory();
3729 uint fill = RawStores;
3730 for (uint i = fill; i < req(); i++) {
3731 Node* n = in(i);
3732 if (n->is_top() || n == zmem) continue; // skip
3733 if (fill < i) set_req(fill, n); // compact
3734 ++fill;
3735 }
3736 // delete any empty spaces created:
3737 while (fill < req()) {
3738 del_req(fill);
3739 }
3740 }
3741
3742 // Helper for remembering which stores go with which offsets.
3743 intptr_t InitializeNode::get_store_offset(Node* st, PhaseValues* phase) {
3744 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
3745 intptr_t offset = -1;
3746 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
3747 phase, offset);
3748 if (base == nullptr) return -1; // something is dead,
3749 if (offset < 0) return -1; // dead, dead
3750 return offset;
3751 }
3752
3753 // Helper for proving that an initialization expression is
3754 // "simple enough" to be folded into an object initialization.
3755 // Attempts to prove that a store's initial value 'n' can be captured
3756 // within the initialization without creating a vicious cycle, such as:
3757 // { Foo p = new Foo(); p.next = p; }
3758 // True for constants and parameters and small combinations thereof.
3759 bool InitializeNode::detect_init_independence(Node* value, PhaseGVN* phase) {
3760 ResourceMark rm;
3761 Unique_Node_List worklist;
3762 worklist.push(value);
3763
3764 uint complexity_limit = 20;
3765 for (uint j = 0; j < worklist.size(); j++) {
3766 if (j >= complexity_limit) {
3767 return false; // Bail out if processed too many nodes
3768 }
3769
3770 Node* n = worklist.at(j);
3771 if (n == nullptr) continue; // (can this really happen?)
3772 if (n->is_Proj()) n = n->in(0);
3773 if (n == this) return false; // found a cycle
3774 if (n->is_Con()) continue;
3775 if (n->is_Start()) continue; // params, etc., are OK
3776 if (n->is_Root()) continue; // even better
3777
3778 // There cannot be any dependency if 'n' is a CFG node that dominates the current allocation
3779 if (n->is_CFG() && phase->is_dominator(n, allocation())) {
3780 continue;
3781 }
3782
3783 Node* ctl = n->in(0);
3784 if (ctl != nullptr && !ctl->is_top()) {
3785 if (ctl->is_Proj()) ctl = ctl->in(0);
3786 if (ctl == this) return false;
3787
3788 // If we already know that the enclosing memory op is pinned right after
3789 // the init, then any control flow that the store has picked up
3790 // must have preceded the init, or else be equal to the init.
3791 // Even after loop optimizations (which might change control edges)
3792 // a store is never pinned *before* the availability of its inputs.
3793 if (!MemNode::all_controls_dominate(n, this))
3794 return false; // failed to prove a good control
3795 }
3796
3797 // Check data edges for possible dependencies on 'this'.
3798 for (uint i = 1; i < n->req(); i++) {
3799 Node* m = n->in(i);
3800 if (m == nullptr || m == n || m->is_top()) continue;
3801
3802 // Only process data inputs once
3803 worklist.push(m);
3804 }
3805 }
3806
3807 return true;
3808 }
3809
3810 // Here are all the checks a Store must pass before it can be moved into
3811 // an initialization. Returns zero if a check fails.
3812 // On success, returns the (constant) offset to which the store applies,
3813 // within the initialized memory.
3814 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseGVN* phase, bool can_reshape) {
3815 const int FAIL = 0;
3816 if (st->req() != MemNode::ValueIn + 1)
3817 return FAIL; // an inscrutable StoreNode (card mark?)
3818 Node* ctl = st->in(MemNode::Control);
3819 if (!(ctl != nullptr && ctl->is_Proj() && ctl->in(0) == this))
3820 return FAIL; // must be unconditional after the initialization
3821 Node* mem = st->in(MemNode::Memory);
3822 if (!(mem->is_Proj() && mem->in(0) == this))
3823 return FAIL; // must not be preceded by other stores
3824 Node* adr = st->in(MemNode::Address);
3825 intptr_t offset;
3826 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
3827 if (alloc == nullptr)
3828 return FAIL; // inscrutable address
3829 if (alloc != allocation())
3830 return FAIL; // wrong allocation! (store needs to float up)
3831 int size_in_bytes = st->memory_size();
3832 if ((size_in_bytes != 0) && (offset % size_in_bytes) != 0) {
3833 return FAIL; // mismatched access
3834 }
3835 Node* val = st->in(MemNode::ValueIn);
3836
3837 if (!detect_init_independence(val, phase))
3838 return FAIL; // stored value must be 'simple enough'
3839
3840 // The Store can be captured only if nothing after the allocation
3841 // and before the Store is using the memory location that the store
3842 // overwrites.
3843 bool failed = false;
3844 // If is_complete_with_arraycopy() is true the shape of the graph is
3845 // well defined and is safe so no need for extra checks.
3846 if (!is_complete_with_arraycopy()) {
3847 // We are going to look at each use of the memory state following
3848 // the allocation to make sure nothing reads the memory that the
3849 // Store writes.
3850 const TypePtr* t_adr = phase->type(adr)->isa_ptr();
3851 int alias_idx = phase->C->get_alias_index(t_adr);
3852 ResourceMark rm;
3853 Unique_Node_List mems;
3854 mems.push(mem);
3855 Node* unique_merge = nullptr;
3856 for (uint next = 0; next < mems.size(); ++next) {
3857 Node *m = mems.at(next);
3858 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
3859 Node *n = m->fast_out(j);
3860 if (n->outcnt() == 0) {
3861 continue;
3862 }
3863 if (n == st) {
3864 continue;
3865 } else if (n->in(0) != nullptr && n->in(0) != ctl) {
3866 // If the control of this use is different from the control
3867 // of the Store which is right after the InitializeNode then
3868 // this node cannot be between the InitializeNode and the
3869 // Store.
3870 continue;
3871 } else if (n->is_MergeMem()) {
3872 if (n->as_MergeMem()->memory_at(alias_idx) == m) {
3873 // We can hit a MergeMemNode (that will likely go away
3874 // later) that is a direct use of the memory state
3875 // following the InitializeNode on the same slice as the
3876 // store node that we'd like to capture. We need to check
3877 // the uses of the MergeMemNode.
3878 mems.push(n);
3879 }
3880 } else if (n->is_Mem()) {
3881 Node* other_adr = n->in(MemNode::Address);
3882 if (other_adr == adr) {
3883 failed = true;
3884 break;
3885 } else {
3886 const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr();
3887 if (other_t_adr != nullptr) {
3888 int other_alias_idx = phase->C->get_alias_index(other_t_adr);
3889 if (other_alias_idx == alias_idx) {
3890 // A load from the same memory slice as the store right
3891 // after the InitializeNode. We check the control of the
3892 // object/array that is loaded from. If it's the same as
3893 // the store control then we cannot capture the store.
3894 assert(!n->is_Store(), "2 stores to same slice on same control?");
3895 Node* base = other_adr;
3896 assert(base->is_AddP(), "should be addp but is %s", base->Name());
3897 base = base->in(AddPNode::Base);
3898 if (base != nullptr) {
3899 base = base->uncast();
3900 if (base->is_Proj() && base->in(0) == alloc) {
3901 failed = true;
3902 break;
3903 }
3904 }
3905 }
3906 }
3907 }
3908 } else {
3909 failed = true;
3910 break;
3911 }
3912 }
3913 }
3914 }
3915 if (failed) {
3916 if (!can_reshape) {
3917 // We decided we couldn't capture the store during parsing. We
3918 // should try again during the next IGVN once the graph is
3919 // cleaner.
3920 phase->C->record_for_igvn(st);
3921 }
3922 return FAIL;
3923 }
3924
3925 return offset; // success
3926 }
3927
3928 // Find the captured store in(i) which corresponds to the range
3929 // [start..start+size) in the initialized object.
3930 // If there is one, return its index i. If there isn't, return the
3931 // negative of the index where it should be inserted.
3932 // Return 0 if the queried range overlaps an initialization boundary
3933 // or if dead code is encountered.
3934 // If size_in_bytes is zero, do not bother with overlap checks.
3935 int InitializeNode::captured_store_insertion_point(intptr_t start,
3936 int size_in_bytes,
3937 PhaseValues* phase) {
3938 const int FAIL = 0, MAX_STORE = MAX2(BytesPerLong, (int)MaxVectorSize);
3939
3940 if (is_complete())
3941 return FAIL; // arraycopy got here first; punt
3942
3943 assert(allocation() != nullptr, "must be present");
3944
3945 // no negatives, no header fields:
3946 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
3947
3948 // after a certain size, we bail out on tracking all the stores:
3949 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3950 if (start >= ti_limit) return FAIL;
3951
3952 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
3953 if (i >= limit) return -(int)i; // not found; here is where to put it
3954
3955 Node* st = in(i);
3956 intptr_t st_off = get_store_offset(st, phase);
3957 if (st_off < 0) {
3958 if (st != zero_memory()) {
3959 return FAIL; // bail out if there is dead garbage
3960 }
3961 } else if (st_off > start) {
3962 // ...we are done, since stores are ordered
3963 if (st_off < start + size_in_bytes) {
3964 return FAIL; // the next store overlaps
3965 }
3966 return -(int)i; // not found; here is where to put it
3967 } else if (st_off < start) {
3968 assert(st->as_Store()->memory_size() <= MAX_STORE, "");
3969 if (size_in_bytes != 0 &&
3970 start < st_off + MAX_STORE &&
3971 start < st_off + st->as_Store()->memory_size()) {
3972 return FAIL; // the previous store overlaps
3973 }
3974 } else {
3975 if (size_in_bytes != 0 &&
3976 st->as_Store()->memory_size() != size_in_bytes) {
3977 return FAIL; // mismatched store size
3978 }
3979 return i;
3980 }
3981
3982 ++i;
3983 }
3984 }
3985
3986 // Look for a captured store which initializes at the offset 'start'
3987 // with the given size. If there is no such store, and no other
3988 // initialization interferes, then return zero_memory (the memory
3989 // projection of the AllocateNode).
3990 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
3991 PhaseValues* phase) {
3992 assert(stores_are_sane(phase), "");
3993 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3994 if (i == 0) {
3995 return nullptr; // something is dead
3996 } else if (i < 0) {
3997 return zero_memory(); // just primordial zero bits here
3998 } else {
3999 Node* st = in(i); // here is the store at this position
4000 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
4001 return st;
4002 }
4003 }
4004
4005 // Create, as a raw pointer, an address within my new object at 'offset'.
4006 Node* InitializeNode::make_raw_address(intptr_t offset,
4007 PhaseGVN* phase) {
4008 Node* addr = in(RawAddress);
4009 if (offset != 0) {
4010 Compile* C = phase->C;
4011 addr = phase->transform( new AddPNode(C->top(), addr,
4012 phase->MakeConX(offset)) );
4013 }
4014 return addr;
4015 }
4016
4017 // Clone the given store, converting it into a raw store
4018 // initializing a field or element of my new object.
4019 // Caller is responsible for retiring the original store,
4020 // with subsume_node or the like.
4021 //
4022 // From the example above InitializeNode::InitializeNode,
4023 // here are the old stores to be captured:
4024 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
4025 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
4026 //
4027 // Here is the changed code; note the extra edges on init:
4028 // alloc = (Allocate ...)
4029 // rawoop = alloc.RawAddress
4030 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
4031 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
4032 // init = (Initialize alloc.Control alloc.Memory rawoop
4033 // rawstore1 rawstore2)
4034 //
4035 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
4036 PhaseGVN* phase, bool can_reshape) {
4037 assert(stores_are_sane(phase), "");
4038
4039 if (start < 0) return nullptr;
4040 assert(can_capture_store(st, phase, can_reshape) == start, "sanity");
4041
4042 Compile* C = phase->C;
4043 int size_in_bytes = st->memory_size();
4044 int i = captured_store_insertion_point(start, size_in_bytes, phase);
4045 if (i == 0) return nullptr; // bail out
4046 Node* prev_mem = nullptr; // raw memory for the captured store
4047 if (i > 0) {
4048 prev_mem = in(i); // there is a pre-existing store under this one
4049 set_req(i, C->top()); // temporarily disconnect it
4050 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
4051 } else {
4052 i = -i; // no pre-existing store
4053 prev_mem = zero_memory(); // a slice of the newly allocated object
4054 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
4055 set_req(--i, C->top()); // reuse this edge; it has been folded away
4056 else
4057 ins_req(i, C->top()); // build a new edge
4058 }
4059 Node* new_st = st->clone();
4060 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
4061 new_st->set_req(MemNode::Control, in(Control));
4062 new_st->set_req(MemNode::Memory, prev_mem);
4063 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
4064 bs->eliminate_gc_barrier_data(new_st);
4065 new_st = phase->transform(new_st);
4066
4067 // At this point, new_st might have swallowed a pre-existing store
4068 // at the same offset, or perhaps new_st might have disappeared,
4069 // if it redundantly stored the same value (or zero to fresh memory).
4070
4071 // In any case, wire it in:
4072 PhaseIterGVN* igvn = phase->is_IterGVN();
4073 if (igvn) {
4074 igvn->rehash_node_delayed(this);
4075 }
4076 set_req(i, new_st);
4077
4078 // The caller may now kill the old guy.
4079 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
4080 assert(check_st == new_st || check_st == nullptr, "must be findable");
4081 assert(!is_complete(), "");
4082 return new_st;
4083 }
4084
4085 static bool store_constant(jlong* tiles, int num_tiles,
4086 intptr_t st_off, int st_size,
4087 jlong con) {
4088 if ((st_off & (st_size-1)) != 0)
4089 return false; // strange store offset (assume size==2**N)
4090 address addr = (address)tiles + st_off;
4091 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
4092 switch (st_size) {
4093 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
4094 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
4095 case sizeof(jint): *(jint*) addr = (jint) con; break;
4096 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
4097 default: return false; // strange store size (detect size!=2**N here)
4098 }
4099 return true; // return success to caller
4100 }
4101
4102 // Coalesce subword constants into int constants and possibly
4103 // into long constants. The goal, if the CPU permits,
4104 // is to initialize the object with a small number of 64-bit tiles.
4105 // Also, convert floating-point constants to bit patterns.
4106 // Non-constants are not relevant to this pass.
4107 //
4108 // In terms of the running example on InitializeNode::InitializeNode
4109 // and InitializeNode::capture_store, here is the transformation
4110 // of rawstore1 and rawstore2 into rawstore12:
4111 // alloc = (Allocate ...)
4112 // rawoop = alloc.RawAddress
4113 // tile12 = 0x00010002
4114 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
4115 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
4116 //
4117 void
4118 InitializeNode::coalesce_subword_stores(intptr_t header_size,
4119 Node* size_in_bytes,
4120 PhaseGVN* phase) {
4121 Compile* C = phase->C;
4122
4123 assert(stores_are_sane(phase), "");
4124 // Note: After this pass, they are not completely sane,
4125 // since there may be some overlaps.
4126
4127 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
4128
4129 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
4130 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
4131 size_limit = MIN2(size_limit, ti_limit);
4132 size_limit = align_up(size_limit, BytesPerLong);
4133 int num_tiles = size_limit / BytesPerLong;
4134
4135 // allocate space for the tile map:
4136 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
4137 jlong tiles_buf[small_len];
4138 Node* nodes_buf[small_len];
4139 jlong inits_buf[small_len];
4140 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
4141 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
4142 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
4143 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
4144 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
4145 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
4146 // tiles: exact bitwise model of all primitive constants
4147 // nodes: last constant-storing node subsumed into the tiles model
4148 // inits: which bytes (in each tile) are touched by any initializations
4149
4150 //// Pass A: Fill in the tile model with any relevant stores.
4151
4152 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
4153 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
4154 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
4155 Node* zmem = zero_memory(); // initially zero memory state
4156 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
4157 Node* st = in(i);
4158 intptr_t st_off = get_store_offset(st, phase);
4159
4160 // Figure out the store's offset and constant value:
4161 if (st_off < header_size) continue; //skip (ignore header)
4162 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
4163 int st_size = st->as_Store()->memory_size();
4164 if (st_off + st_size > size_limit) break;
4165
4166 // Record which bytes are touched, whether by constant or not.
4167 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
4168 continue; // skip (strange store size)
4169
4170 const Type* val = phase->type(st->in(MemNode::ValueIn));
4171 if (!val->singleton()) continue; //skip (non-con store)
4172 BasicType type = val->basic_type();
4173
4174 jlong con = 0;
4175 switch (type) {
4176 case T_INT: con = val->is_int()->get_con(); break;
4177 case T_LONG: con = val->is_long()->get_con(); break;
4178 case T_FLOAT: con = jint_cast(val->getf()); break;
4179 case T_DOUBLE: con = jlong_cast(val->getd()); break;
4180 default: continue; //skip (odd store type)
4181 }
4182
4183 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
4184 st->Opcode() == Op_StoreL) {
4185 continue; // This StoreL is already optimal.
4186 }
4187
4188 // Store down the constant.
4189 store_constant(tiles, num_tiles, st_off, st_size, con);
4190
4191 intptr_t j = st_off >> LogBytesPerLong;
4192
4193 if (type == T_INT && st_size == BytesPerInt
4194 && (st_off & BytesPerInt) == BytesPerInt) {
4195 jlong lcon = tiles[j];
4196 if (!Matcher::isSimpleConstant64(lcon) &&
4197 st->Opcode() == Op_StoreI) {
4198 // This StoreI is already optimal by itself.
4199 jint* intcon = (jint*) &tiles[j];
4200 intcon[1] = 0; // undo the store_constant()
4201
4202 // If the previous store is also optimal by itself, back up and
4203 // undo the action of the previous loop iteration... if we can.
4204 // But if we can't, just let the previous half take care of itself.
4205 st = nodes[j];
4206 st_off -= BytesPerInt;
4207 con = intcon[0];
4208 if (con != 0 && st != nullptr && st->Opcode() == Op_StoreI) {
4209 assert(st_off >= header_size, "still ignoring header");
4210 assert(get_store_offset(st, phase) == st_off, "must be");
4211 assert(in(i-1) == zmem, "must be");
4212 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
4213 assert(con == tcon->is_int()->get_con(), "must be");
4214 // Undo the effects of the previous loop trip, which swallowed st:
4215 intcon[0] = 0; // undo store_constant()
4216 set_req(i-1, st); // undo set_req(i, zmem)
4217 nodes[j] = nullptr; // undo nodes[j] = st
4218 --old_subword; // undo ++old_subword
4219 }
4220 continue; // This StoreI is already optimal.
4221 }
4222 }
4223
4224 // This store is not needed.
4225 set_req(i, zmem);
4226 nodes[j] = st; // record for the moment
4227 if (st_size < BytesPerLong) // something has changed
4228 ++old_subword; // includes int/float, but who's counting...
4229 else ++old_long;
4230 }
4231
4232 if ((old_subword + old_long) == 0)
4233 return; // nothing more to do
4234
4235 //// Pass B: Convert any non-zero tiles into optimal constant stores.
4236 // Be sure to insert them before overlapping non-constant stores.
4237 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
4238 for (int j = 0; j < num_tiles; j++) {
4239 jlong con = tiles[j];
4240 jlong init = inits[j];
4241 if (con == 0) continue;
4242 jint con0, con1; // split the constant, address-wise
4243 jint init0, init1; // split the init map, address-wise
4244 { union { jlong con; jint intcon[2]; } u;
4245 u.con = con;
4246 con0 = u.intcon[0];
4247 con1 = u.intcon[1];
4248 u.con = init;
4249 init0 = u.intcon[0];
4250 init1 = u.intcon[1];
4251 }
4252
4253 Node* old = nodes[j];
4254 assert(old != nullptr, "need the prior store");
4255 intptr_t offset = (j * BytesPerLong);
4256
4257 bool split = !Matcher::isSimpleConstant64(con);
4258
4259 if (offset < header_size) {
4260 assert(offset + BytesPerInt >= header_size, "second int counts");
4261 assert(*(jint*)&tiles[j] == 0, "junk in header");
4262 split = true; // only the second word counts
4263 // Example: int a[] = { 42 ... }
4264 } else if (con0 == 0 && init0 == -1) {
4265 split = true; // first word is covered by full inits
4266 // Example: int a[] = { ... foo(), 42 ... }
4267 } else if (con1 == 0 && init1 == -1) {
4268 split = true; // second word is covered by full inits
4269 // Example: int a[] = { ... 42, foo() ... }
4270 }
4271
4272 // Here's a case where init0 is neither 0 nor -1:
4273 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
4274 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
4275 // In this case the tile is not split; it is (jlong)42.
4276 // The big tile is stored down, and then the foo() value is inserted.
4277 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
4278
4279 Node* ctl = old->in(MemNode::Control);
4280 Node* adr = make_raw_address(offset, phase);
4281 const TypePtr* atp = TypeRawPtr::BOTTOM;
4282
4283 // One or two coalesced stores to plop down.
4284 Node* st[2];
4285 intptr_t off[2];
4286 int nst = 0;
4287 if (!split) {
4288 ++new_long;
4289 off[nst] = offset;
4290 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
4291 phase->longcon(con), T_LONG, MemNode::unordered);
4292 } else {
4293 // Omit either if it is a zero.
4294 if (con0 != 0) {
4295 ++new_int;
4296 off[nst] = offset;
4297 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
4298 phase->intcon(con0), T_INT, MemNode::unordered);
4299 }
4300 if (con1 != 0) {
4301 ++new_int;
4302 offset += BytesPerInt;
4303 adr = make_raw_address(offset, phase);
4304 off[nst] = offset;
4305 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
4306 phase->intcon(con1), T_INT, MemNode::unordered);
4307 }
4308 }
4309
4310 // Insert second store first, then the first before the second.
4311 // Insert each one just before any overlapping non-constant stores.
4312 while (nst > 0) {
4313 Node* st1 = st[--nst];
4314 C->copy_node_notes_to(st1, old);
4315 st1 = phase->transform(st1);
4316 offset = off[nst];
4317 assert(offset >= header_size, "do not smash header");
4318 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
4319 guarantee(ins_idx != 0, "must re-insert constant store");
4320 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
4321 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
4322 set_req(--ins_idx, st1);
4323 else
4324 ins_req(ins_idx, st1);
4325 }
4326 }
4327
4328 if (PrintCompilation && WizardMode)
4329 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
4330 old_subword, old_long, new_int, new_long);
4331 if (C->log() != nullptr)
4332 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
4333 old_subword, old_long, new_int, new_long);
4334
4335 // Clean up any remaining occurrences of zmem:
4336 remove_extra_zeroes();
4337 }
4338
4339 // Explore forward from in(start) to find the first fully initialized
4340 // word, and return its offset. Skip groups of subword stores which
4341 // together initialize full words. If in(start) is itself part of a
4342 // fully initialized word, return the offset of in(start). If there
4343 // are no following full-word stores, or if something is fishy, return
4344 // a negative value.
4345 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
4346 int int_map = 0;
4347 intptr_t int_map_off = 0;
4348 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
4349
4350 for (uint i = start, limit = req(); i < limit; i++) {
4351 Node* st = in(i);
4352
4353 intptr_t st_off = get_store_offset(st, phase);
4354 if (st_off < 0) break; // return conservative answer
4355
4356 int st_size = st->as_Store()->memory_size();
4357 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
4358 return st_off; // we found a complete word init
4359 }
4360
4361 // update the map:
4362
4363 intptr_t this_int_off = align_down(st_off, BytesPerInt);
4364 if (this_int_off != int_map_off) {
4365 // reset the map:
4366 int_map = 0;
4367 int_map_off = this_int_off;
4368 }
4369
4370 int subword_off = st_off - this_int_off;
4371 int_map |= right_n_bits(st_size) << subword_off;
4372 if ((int_map & FULL_MAP) == FULL_MAP) {
4373 return this_int_off; // we found a complete word init
4374 }
4375
4376 // Did this store hit or cross the word boundary?
4377 intptr_t next_int_off = align_down(st_off + st_size, BytesPerInt);
4378 if (next_int_off == this_int_off + BytesPerInt) {
4379 // We passed the current int, without fully initializing it.
4380 int_map_off = next_int_off;
4381 int_map >>= BytesPerInt;
4382 } else if (next_int_off > this_int_off + BytesPerInt) {
4383 // We passed the current and next int.
4384 return this_int_off + BytesPerInt;
4385 }
4386 }
4387
4388 return -1;
4389 }
4390
4391
4392 // Called when the associated AllocateNode is expanded into CFG.
4393 // At this point, we may perform additional optimizations.
4394 // Linearize the stores by ascending offset, to make memory
4395 // activity as coherent as possible.
4396 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
4397 intptr_t header_size,
4398 Node* size_in_bytes,
4399 PhaseIterGVN* phase) {
4400 assert(!is_complete(), "not already complete");
4401 assert(stores_are_sane(phase), "");
4402 assert(allocation() != nullptr, "must be present");
4403
4404 remove_extra_zeroes();
4405
4406 if (ReduceFieldZeroing || ReduceBulkZeroing)
4407 // reduce instruction count for common initialization patterns
4408 coalesce_subword_stores(header_size, size_in_bytes, phase);
4409
4410 Node* zmem = zero_memory(); // initially zero memory state
4411 Node* inits = zmem; // accumulating a linearized chain of inits
4412 #ifdef ASSERT
4413 intptr_t first_offset = allocation()->minimum_header_size();
4414 intptr_t last_init_off = first_offset; // previous init offset
4415 intptr_t last_init_end = first_offset; // previous init offset+size
4416 intptr_t last_tile_end = first_offset; // previous tile offset+size
4417 #endif
4418 intptr_t zeroes_done = header_size;
4419
4420 bool do_zeroing = true; // we might give up if inits are very sparse
4421 int big_init_gaps = 0; // how many large gaps have we seen?
4422
4423 if (UseTLAB && ZeroTLAB) do_zeroing = false;
4424 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
4425
4426 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
4427 Node* st = in(i);
4428 intptr_t st_off = get_store_offset(st, phase);
4429 if (st_off < 0)
4430 break; // unknown junk in the inits
4431 if (st->in(MemNode::Memory) != zmem)
4432 break; // complicated store chains somehow in list
4433
4434 int st_size = st->as_Store()->memory_size();
4435 intptr_t next_init_off = st_off + st_size;
4436
4437 if (do_zeroing && zeroes_done < next_init_off) {
4438 // See if this store needs a zero before it or under it.
4439 intptr_t zeroes_needed = st_off;
4440
4441 if (st_size < BytesPerInt) {
4442 // Look for subword stores which only partially initialize words.
4443 // If we find some, we must lay down some word-level zeroes first,
4444 // underneath the subword stores.
4445 //
4446 // Examples:
4447 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
4448 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
4449 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
4450 //
4451 // Note: coalesce_subword_stores may have already done this,
4452 // if it was prompted by constant non-zero subword initializers.
4453 // But this case can still arise with non-constant stores.
4454
4455 intptr_t next_full_store = find_next_fullword_store(i, phase);
4456
4457 // In the examples above:
4458 // in(i) p q r s x y z
4459 // st_off 12 13 14 15 12 13 14
4460 // st_size 1 1 1 1 1 1 1
4461 // next_full_s. 12 16 16 16 16 16 16
4462 // z's_done 12 16 16 16 12 16 12
4463 // z's_needed 12 16 16 16 16 16 16
4464 // zsize 0 0 0 0 4 0 4
4465 if (next_full_store < 0) {
4466 // Conservative tack: Zero to end of current word.
4467 zeroes_needed = align_up(zeroes_needed, BytesPerInt);
4468 } else {
4469 // Zero to beginning of next fully initialized word.
4470 // Or, don't zero at all, if we are already in that word.
4471 assert(next_full_store >= zeroes_needed, "must go forward");
4472 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
4473 zeroes_needed = next_full_store;
4474 }
4475 }
4476
4477 if (zeroes_needed > zeroes_done) {
4478 intptr_t zsize = zeroes_needed - zeroes_done;
4479 // Do some incremental zeroing on rawmem, in parallel with inits.
4480 zeroes_done = align_down(zeroes_done, BytesPerInt);
4481 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
4482 zeroes_done, zeroes_needed,
4483 phase);
4484 zeroes_done = zeroes_needed;
4485 if (zsize > InitArrayShortSize && ++big_init_gaps > 2)
4486 do_zeroing = false; // leave the hole, next time
4487 }
4488 }
4489
4490 // Collect the store and move on:
4491 phase->replace_input_of(st, MemNode::Memory, inits);
4492 inits = st; // put it on the linearized chain
4493 set_req(i, zmem); // unhook from previous position
4494
4495 if (zeroes_done == st_off)
4496 zeroes_done = next_init_off;
4497
4498 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
4499
4500 #ifdef ASSERT
4501 // Various order invariants. Weaker than stores_are_sane because
4502 // a large constant tile can be filled in by smaller non-constant stores.
4503 assert(st_off >= last_init_off, "inits do not reverse");
4504 last_init_off = st_off;
4505 const Type* val = nullptr;
4506 if (st_size >= BytesPerInt &&
4507 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
4508 (int)val->basic_type() < (int)T_OBJECT) {
4509 assert(st_off >= last_tile_end, "tiles do not overlap");
4510 assert(st_off >= last_init_end, "tiles do not overwrite inits");
4511 last_tile_end = MAX2(last_tile_end, next_init_off);
4512 } else {
4513 intptr_t st_tile_end = align_up(next_init_off, BytesPerLong);
4514 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
4515 assert(st_off >= last_init_end, "inits do not overlap");
4516 last_init_end = next_init_off; // it's a non-tile
4517 }
4518 #endif //ASSERT
4519 }
4520
4521 remove_extra_zeroes(); // clear out all the zmems left over
4522 add_req(inits);
4523
4524 if (!(UseTLAB && ZeroTLAB)) {
4525 // If anything remains to be zeroed, zero it all now.
4526 zeroes_done = align_down(zeroes_done, BytesPerInt);
4527 // if it is the last unused 4 bytes of an instance, forget about it
4528 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
4529 if (zeroes_done + BytesPerLong >= size_limit) {
4530 AllocateNode* alloc = allocation();
4531 assert(alloc != nullptr, "must be present");
4532 if (alloc != nullptr && alloc->Opcode() == Op_Allocate) {
4533 Node* klass_node = alloc->in(AllocateNode::KlassNode);
4534 ciKlass* k = phase->type(klass_node)->is_instklassptr()->instance_klass();
4535 if (zeroes_done == k->layout_helper())
4536 zeroes_done = size_limit;
4537 }
4538 }
4539 if (zeroes_done < size_limit) {
4540 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
4541 zeroes_done, size_in_bytes, phase);
4542 }
4543 }
4544
4545 set_complete(phase);
4546 return rawmem;
4547 }
4548
4549
4550 #ifdef ASSERT
4551 bool InitializeNode::stores_are_sane(PhaseValues* phase) {
4552 if (is_complete())
4553 return true; // stores could be anything at this point
4554 assert(allocation() != nullptr, "must be present");
4555 intptr_t last_off = allocation()->minimum_header_size();
4556 for (uint i = InitializeNode::RawStores; i < req(); i++) {
4557 Node* st = in(i);
4558 intptr_t st_off = get_store_offset(st, phase);
4559 if (st_off < 0) continue; // ignore dead garbage
4560 if (last_off > st_off) {
4561 tty->print_cr("*** bad store offset at %d: " INTX_FORMAT " > " INTX_FORMAT, i, last_off, st_off);
4562 this->dump(2);
4563 assert(false, "ascending store offsets");
4564 return false;
4565 }
4566 last_off = st_off + st->as_Store()->memory_size();
4567 }
4568 return true;
4569 }
4570 #endif //ASSERT
4571
4572
4573
4574
4575 //============================MergeMemNode=====================================
4576 //
4577 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
4578 // contributing store or call operations. Each contributor provides the memory
4579 // state for a particular "alias type" (see Compile::alias_type). For example,
4580 // if a MergeMem has an input X for alias category #6, then any memory reference
4581 // to alias category #6 may use X as its memory state input, as an exact equivalent
4582 // to using the MergeMem as a whole.
4583 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
4584 //
4585 // (Here, the <N> notation gives the index of the relevant adr_type.)
4586 //
4587 // In one special case (and more cases in the future), alias categories overlap.
4588 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
4589 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
4590 // it is exactly equivalent to that state W:
4591 // MergeMem(<Bot>: W) <==> W
4592 //
4593 // Usually, the merge has more than one input. In that case, where inputs
4594 // overlap (i.e., one is Bot), the narrower alias type determines the memory
4595 // state for that type, and the wider alias type (Bot) fills in everywhere else:
4596 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
4597 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
4598 //
4599 // A merge can take a "wide" memory state as one of its narrow inputs.
4600 // This simply means that the merge observes out only the relevant parts of
4601 // the wide input. That is, wide memory states arriving at narrow merge inputs
4602 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
4603 //
4604 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
4605 // and that memory slices "leak through":
4606 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
4607 //
4608 // But, in such a cascade, repeated memory slices can "block the leak":
4609 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
4610 //
4611 // In the last example, Y is not part of the combined memory state of the
4612 // outermost MergeMem. The system must, of course, prevent unschedulable
4613 // memory states from arising, so you can be sure that the state Y is somehow
4614 // a precursor to state Y'.
4615 //
4616 //
4617 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
4618 // of each MergeMemNode array are exactly the numerical alias indexes, including
4619 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
4620 // Compile::alias_type (and kin) produce and manage these indexes.
4621 //
4622 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
4623 // (Note that this provides quick access to the top node inside MergeMem methods,
4624 // without the need to reach out via TLS to Compile::current.)
4625 //
4626 // As a consequence of what was just described, a MergeMem that represents a full
4627 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
4628 // containing all alias categories.
4629 //
4630 // MergeMem nodes never (?) have control inputs, so in(0) is null.
4631 //
4632 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
4633 // a memory state for the alias type <N>, or else the top node, meaning that
4634 // there is no particular input for that alias type. Note that the length of
4635 // a MergeMem is variable, and may be extended at any time to accommodate new
4636 // memory states at larger alias indexes. When merges grow, they are of course
4637 // filled with "top" in the unused in() positions.
4638 //
4639 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
4640 // (Top was chosen because it works smoothly with passes like GCM.)
4641 //
4642 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
4643 // the type of random VM bits like TLS references.) Since it is always the
4644 // first non-Bot memory slice, some low-level loops use it to initialize an
4645 // index variable: for (i = AliasIdxRaw; i < req(); i++).
4646 //
4647 //
4648 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
4649 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
4650 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
4651 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
4652 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
4653 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
4654 //
4655 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
4656 // really that different from the other memory inputs. An abbreviation called
4657 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
4658 //
4659 //
4660 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
4661 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
4662 // that "emerges though" the base memory will be marked as excluding the alias types
4663 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
4664 //
4665 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
4666 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
4667 //
4668 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
4669 // (It is currently unimplemented.) As you can see, the resulting merge is
4670 // actually a disjoint union of memory states, rather than an overlay.
4671 //
4672
4673 //------------------------------MergeMemNode-----------------------------------
4674 Node* MergeMemNode::make_empty_memory() {
4675 Node* empty_memory = (Node*) Compile::current()->top();
4676 assert(empty_memory->is_top(), "correct sentinel identity");
4677 return empty_memory;
4678 }
4679
4680 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
4681 init_class_id(Class_MergeMem);
4682 // all inputs are nullified in Node::Node(int)
4683 // set_input(0, nullptr); // no control input
4684
4685 // Initialize the edges uniformly to top, for starters.
4686 Node* empty_mem = make_empty_memory();
4687 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
4688 init_req(i,empty_mem);
4689 }
4690 assert(empty_memory() == empty_mem, "");
4691
4692 if( new_base != nullptr && new_base->is_MergeMem() ) {
4693 MergeMemNode* mdef = new_base->as_MergeMem();
4694 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
4695 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
4696 mms.set_memory(mms.memory2());
4697 }
4698 assert(base_memory() == mdef->base_memory(), "");
4699 } else {
4700 set_base_memory(new_base);
4701 }
4702 }
4703
4704 // Make a new, untransformed MergeMem with the same base as 'mem'.
4705 // If mem is itself a MergeMem, populate the result with the same edges.
4706 MergeMemNode* MergeMemNode::make(Node* mem) {
4707 return new MergeMemNode(mem);
4708 }
4709
4710 //------------------------------cmp--------------------------------------------
4711 uint MergeMemNode::hash() const { return NO_HASH; }
4712 bool MergeMemNode::cmp( const Node &n ) const {
4713 return (&n == this); // Always fail except on self
4714 }
4715
4716 //------------------------------Identity---------------------------------------
4717 Node* MergeMemNode::Identity(PhaseGVN* phase) {
4718 // Identity if this merge point does not record any interesting memory
4719 // disambiguations.
4720 Node* base_mem = base_memory();
4721 Node* empty_mem = empty_memory();
4722 if (base_mem != empty_mem) { // Memory path is not dead?
4723 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4724 Node* mem = in(i);
4725 if (mem != empty_mem && mem != base_mem) {
4726 return this; // Many memory splits; no change
4727 }
4728 }
4729 }
4730 return base_mem; // No memory splits; ID on the one true input
4731 }
4732
4733 //------------------------------Ideal------------------------------------------
4734 // This method is invoked recursively on chains of MergeMem nodes
4735 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4736 // Remove chain'd MergeMems
4737 //
4738 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
4739 // relative to the "in(Bot)". Since we are patching both at the same time,
4740 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
4741 // but rewrite each "in(i)" relative to the new "in(Bot)".
4742 Node *progress = nullptr;
4743
4744
4745 Node* old_base = base_memory();
4746 Node* empty_mem = empty_memory();
4747 if (old_base == empty_mem)
4748 return nullptr; // Dead memory path.
4749
4750 MergeMemNode* old_mbase;
4751 if (old_base != nullptr && old_base->is_MergeMem())
4752 old_mbase = old_base->as_MergeMem();
4753 else
4754 old_mbase = nullptr;
4755 Node* new_base = old_base;
4756
4757 // simplify stacked MergeMems in base memory
4758 if (old_mbase) new_base = old_mbase->base_memory();
4759
4760 // the base memory might contribute new slices beyond my req()
4761 if (old_mbase) grow_to_match(old_mbase);
4762
4763 // Note: We do not call verify_sparse on entry, because inputs
4764 // can normalize to the base_memory via subsume_node or similar
4765 // mechanisms. This method repairs that damage.
4766
4767 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
4768
4769 // Look at each slice.
4770 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4771 Node* old_in = in(i);
4772 // calculate the old memory value
4773 Node* old_mem = old_in;
4774 if (old_mem == empty_mem) old_mem = old_base;
4775 assert(old_mem == memory_at(i), "");
4776
4777 // maybe update (reslice) the old memory value
4778
4779 // simplify stacked MergeMems
4780 Node* new_mem = old_mem;
4781 MergeMemNode* old_mmem;
4782 if (old_mem != nullptr && old_mem->is_MergeMem())
4783 old_mmem = old_mem->as_MergeMem();
4784 else
4785 old_mmem = nullptr;
4786 if (old_mmem == this) {
4787 // This can happen if loops break up and safepoints disappear.
4788 // A merge of BotPtr (default) with a RawPtr memory derived from a
4789 // safepoint can be rewritten to a merge of the same BotPtr with
4790 // the BotPtr phi coming into the loop. If that phi disappears
4791 // also, we can end up with a self-loop of the mergemem.
4792 // In general, if loops degenerate and memory effects disappear,
4793 // a mergemem can be left looking at itself. This simply means
4794 // that the mergemem's default should be used, since there is
4795 // no longer any apparent effect on this slice.
4796 // Note: If a memory slice is a MergeMem cycle, it is unreachable
4797 // from start. Update the input to TOP.
4798 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
4799 }
4800 else if (old_mmem != nullptr) {
4801 new_mem = old_mmem->memory_at(i);
4802 }
4803 // else preceding memory was not a MergeMem
4804
4805 // maybe store down a new value
4806 Node* new_in = new_mem;
4807 if (new_in == new_base) new_in = empty_mem;
4808
4809 if (new_in != old_in) {
4810 // Warning: Do not combine this "if" with the previous "if"
4811 // A memory slice might have be be rewritten even if it is semantically
4812 // unchanged, if the base_memory value has changed.
4813 set_req_X(i, new_in, phase);
4814 progress = this; // Report progress
4815 }
4816 }
4817
4818 if (new_base != old_base) {
4819 set_req_X(Compile::AliasIdxBot, new_base, phase);
4820 // Don't use set_base_memory(new_base), because we need to update du.
4821 assert(base_memory() == new_base, "");
4822 progress = this;
4823 }
4824
4825 if( base_memory() == this ) {
4826 // a self cycle indicates this memory path is dead
4827 set_req(Compile::AliasIdxBot, empty_mem);
4828 }
4829
4830 // Resolve external cycles by calling Ideal on a MergeMem base_memory
4831 // Recursion must occur after the self cycle check above
4832 if( base_memory()->is_MergeMem() ) {
4833 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
4834 Node *m = phase->transform(new_mbase); // Rollup any cycles
4835 if( m != nullptr &&
4836 (m->is_top() ||
4837 (m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem)) ) {
4838 // propagate rollup of dead cycle to self
4839 set_req(Compile::AliasIdxBot, empty_mem);
4840 }
4841 }
4842
4843 if( base_memory() == empty_mem ) {
4844 progress = this;
4845 // Cut inputs during Parse phase only.
4846 // During Optimize phase a dead MergeMem node will be subsumed by Top.
4847 if( !can_reshape ) {
4848 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4849 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
4850 }
4851 }
4852 }
4853
4854 if( !progress && base_memory()->is_Phi() && can_reshape ) {
4855 // Check if PhiNode::Ideal's "Split phis through memory merges"
4856 // transform should be attempted. Look for this->phi->this cycle.
4857 uint merge_width = req();
4858 if (merge_width > Compile::AliasIdxRaw) {
4859 PhiNode* phi = base_memory()->as_Phi();
4860 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
4861 if (phi->in(i) == this) {
4862 phase->is_IterGVN()->_worklist.push(phi);
4863 break;
4864 }
4865 }
4866 }
4867 }
4868
4869 assert(progress || verify_sparse(), "please, no dups of base");
4870 return progress;
4871 }
4872
4873 //-------------------------set_base_memory-------------------------------------
4874 void MergeMemNode::set_base_memory(Node *new_base) {
4875 Node* empty_mem = empty_memory();
4876 set_req(Compile::AliasIdxBot, new_base);
4877 assert(memory_at(req()) == new_base, "must set default memory");
4878 // Clear out other occurrences of new_base:
4879 if (new_base != empty_mem) {
4880 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4881 if (in(i) == new_base) set_req(i, empty_mem);
4882 }
4883 }
4884 }
4885
4886 //------------------------------out_RegMask------------------------------------
4887 const RegMask &MergeMemNode::out_RegMask() const {
4888 return RegMask::Empty;
4889 }
4890
4891 //------------------------------dump_spec--------------------------------------
4892 #ifndef PRODUCT
4893 void MergeMemNode::dump_spec(outputStream *st) const {
4894 st->print(" {");
4895 Node* base_mem = base_memory();
4896 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
4897 Node* mem = (in(i) != nullptr) ? memory_at(i) : base_mem;
4898 if (mem == base_mem) { st->print(" -"); continue; }
4899 st->print( " N%d:", mem->_idx );
4900 Compile::current()->get_adr_type(i)->dump_on(st);
4901 }
4902 st->print(" }");
4903 }
4904 #endif // !PRODUCT
4905
4906
4907 #ifdef ASSERT
4908 static bool might_be_same(Node* a, Node* b) {
4909 if (a == b) return true;
4910 if (!(a->is_Phi() || b->is_Phi())) return false;
4911 // phis shift around during optimization
4912 return true; // pretty stupid...
4913 }
4914
4915 // verify a narrow slice (either incoming or outgoing)
4916 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
4917 if (!VerifyAliases) return; // don't bother to verify unless requested
4918 if (VMError::is_error_reported()) return; // muzzle asserts when debugging an error
4919 if (Node::in_dump()) return; // muzzle asserts when printing
4920 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
4921 assert(n != nullptr, "");
4922 // Elide intervening MergeMem's
4923 while (n->is_MergeMem()) {
4924 n = n->as_MergeMem()->memory_at(alias_idx);
4925 }
4926 Compile* C = Compile::current();
4927 const TypePtr* n_adr_type = n->adr_type();
4928 if (n == m->empty_memory()) {
4929 // Implicit copy of base_memory()
4930 } else if (n_adr_type != TypePtr::BOTTOM) {
4931 assert(n_adr_type != nullptr, "new memory must have a well-defined adr_type");
4932 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
4933 } else {
4934 // A few places like make_runtime_call "know" that VM calls are narrow,
4935 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
4936 bool expected_wide_mem = false;
4937 if (n == m->base_memory()) {
4938 expected_wide_mem = true;
4939 } else if (alias_idx == Compile::AliasIdxRaw ||
4940 n == m->memory_at(Compile::AliasIdxRaw)) {
4941 expected_wide_mem = true;
4942 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
4943 // memory can "leak through" calls on channels that
4944 // are write-once. Allow this also.
4945 expected_wide_mem = true;
4946 }
4947 assert(expected_wide_mem, "expected narrow slice replacement");
4948 }
4949 }
4950 #else // !ASSERT
4951 #define verify_memory_slice(m,i,n) (void)(0) // PRODUCT version is no-op
4952 #endif
4953
4954
4955 //-----------------------------memory_at---------------------------------------
4956 Node* MergeMemNode::memory_at(uint alias_idx) const {
4957 assert(alias_idx >= Compile::AliasIdxRaw ||
4958 alias_idx == Compile::AliasIdxBot && !Compile::current()->do_aliasing(),
4959 "must avoid base_memory and AliasIdxTop");
4960
4961 // Otherwise, it is a narrow slice.
4962 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
4963 if (is_empty_memory(n)) {
4964 // the array is sparse; empty slots are the "top" node
4965 n = base_memory();
4966 assert(Node::in_dump()
4967 || n == nullptr || n->bottom_type() == Type::TOP
4968 || n->adr_type() == nullptr // address is TOP
4969 || n->adr_type() == TypePtr::BOTTOM
4970 || n->adr_type() == TypeRawPtr::BOTTOM
4971 || !Compile::current()->do_aliasing(),
4972 "must be a wide memory");
4973 // do_aliasing == false if we are organizing the memory states manually.
4974 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
4975 } else {
4976 // make sure the stored slice is sane
4977 #ifdef ASSERT
4978 if (VMError::is_error_reported() || Node::in_dump()) {
4979 } else if (might_be_same(n, base_memory())) {
4980 // Give it a pass: It is a mostly harmless repetition of the base.
4981 // This can arise normally from node subsumption during optimization.
4982 } else {
4983 verify_memory_slice(this, alias_idx, n);
4984 }
4985 #endif
4986 }
4987 return n;
4988 }
4989
4990 //---------------------------set_memory_at-------------------------------------
4991 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
4992 verify_memory_slice(this, alias_idx, n);
4993 Node* empty_mem = empty_memory();
4994 if (n == base_memory()) n = empty_mem; // collapse default
4995 uint need_req = alias_idx+1;
4996 if (req() < need_req) {
4997 if (n == empty_mem) return; // already the default, so do not grow me
4998 // grow the sparse array
4999 do {
5000 add_req(empty_mem);
5001 } while (req() < need_req);
5002 }
5003 set_req( alias_idx, n );
5004 }
5005
5006
5007
5008 //--------------------------iteration_setup------------------------------------
5009 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
5010 if (other != nullptr) {
5011 grow_to_match(other);
5012 // invariant: the finite support of mm2 is within mm->req()
5013 #ifdef ASSERT
5014 for (uint i = req(); i < other->req(); i++) {
5015 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
5016 }
5017 #endif
5018 }
5019 // Replace spurious copies of base_memory by top.
5020 Node* base_mem = base_memory();
5021 if (base_mem != nullptr && !base_mem->is_top()) {
5022 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
5023 if (in(i) == base_mem)
5024 set_req(i, empty_memory());
5025 }
5026 }
5027 }
5028
5029 //---------------------------grow_to_match-------------------------------------
5030 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
5031 Node* empty_mem = empty_memory();
5032 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
5033 // look for the finite support of the other memory
5034 for (uint i = other->req(); --i >= req(); ) {
5035 if (other->in(i) != empty_mem) {
5036 uint new_len = i+1;
5037 while (req() < new_len) add_req(empty_mem);
5038 break;
5039 }
5040 }
5041 }
5042
5043 //---------------------------verify_sparse-------------------------------------
5044 #ifndef PRODUCT
5045 bool MergeMemNode::verify_sparse() const {
5046 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
5047 Node* base_mem = base_memory();
5048 // The following can happen in degenerate cases, since empty==top.
5049 if (is_empty_memory(base_mem)) return true;
5050 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5051 assert(in(i) != nullptr, "sane slice");
5052 if (in(i) == base_mem) return false; // should have been the sentinel value!
5053 }
5054 return true;
5055 }
5056
5057 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
5058 Node* n;
5059 n = mm->in(idx);
5060 if (mem == n) return true; // might be empty_memory()
5061 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
5062 if (mem == n) return true;
5063 return false;
5064 }
5065 #endif // !PRODUCT