1 /*
2 * Copyright (c) 1997, 2018, 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.
18 *
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.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/systemDictionary.hpp"
27 #include "compiler/compileLog.hpp"
28 #include "gc/shared/barrierSet.hpp"
29 #include "gc/shared/c2/barrierSetC2.hpp"
30 #include "memory/allocation.inline.hpp"
31 #include "memory/resourceArea.hpp"
32 #include "oops/objArrayKlass.hpp"
33 #include "opto/addnode.hpp"
34 #include "opto/arraycopynode.hpp"
35 #include "opto/cfgnode.hpp"
36 #include "opto/compile.hpp"
37 #include "opto/connode.hpp"
38 #include "opto/convertnode.hpp"
39 #include "opto/loopnode.hpp"
40 #include "opto/machnode.hpp"
41 #include "opto/matcher.hpp"
42 #include "opto/memnode.hpp"
43 #include "opto/mulnode.hpp"
44 #include "opto/narrowptrnode.hpp"
45 #include "opto/phaseX.hpp"
46 #include "opto/regmask.hpp"
47 #include "opto/valuetypenode.hpp"
48 #include "utilities/align.hpp"
49 #include "utilities/copy.hpp"
50 #include "utilities/macros.hpp"
51 #include "utilities/vmError.hpp"
52 #if INCLUDE_ZGC
53 #include "gc/z/c2/zBarrierSetC2.hpp"
54 #endif
55
56 // Portions of code courtesy of Clifford Click
57
58 // Optimization - Graph Style
59
60 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st);
61
62 //=============================================================================
63 uint MemNode::size_of() const { return sizeof(*this); }
64
65 const TypePtr *MemNode::adr_type() const {
66 Node* adr = in(Address);
67 if (adr == NULL) return NULL; // node is dead
68 const TypePtr* cross_check = NULL;
69 DEBUG_ONLY(cross_check = _adr_type);
70 return calculate_adr_type(adr->bottom_type(), cross_check);
71 }
72
73 bool MemNode::check_if_adr_maybe_raw(Node* adr) {
74 if (adr != NULL) {
75 if (adr->bottom_type()->base() == Type::RawPtr || adr->bottom_type()->base() == Type::AnyPtr) {
76 return true;
77 }
78 }
79 return false;
80 }
81
82 #ifndef PRODUCT
83 void MemNode::dump_spec(outputStream *st) const {
84 if (in(Address) == NULL) return; // node is dead
85 #ifndef ASSERT
86 // fake the missing field
87 const TypePtr* _adr_type = NULL;
88 if (in(Address) != NULL)
89 _adr_type = in(Address)->bottom_type()->isa_ptr();
90 #endif
91 dump_adr_type(this, _adr_type, st);
92
93 Compile* C = Compile::current();
94 if (C->alias_type(_adr_type)->is_volatile()) {
95 st->print(" Volatile!");
96 }
97 if (_unaligned_access) {
98 st->print(" unaligned");
99 }
100 if (_mismatched_access) {
101 st->print(" mismatched");
102 }
103 }
104
105 void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) {
106 st->print(" @");
107 if (adr_type == NULL) {
108 st->print("NULL");
109 } else {
110 adr_type->dump_on(st);
111 Compile* C = Compile::current();
112 Compile::AliasType* atp = NULL;
113 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type);
114 if (atp == NULL)
115 st->print(", idx=?\?;");
116 else if (atp->index() == Compile::AliasIdxBot)
117 st->print(", idx=Bot;");
118 else if (atp->index() == Compile::AliasIdxTop)
119 st->print(", idx=Top;");
120 else if (atp->index() == Compile::AliasIdxRaw)
121 st->print(", idx=Raw;");
122 else {
123 ciField* field = atp->field();
124 if (field) {
125 st->print(", name=");
126 field->print_name_on(st);
127 }
128 st->print(", idx=%d;", atp->index());
129 }
130 }
131 }
132
133 extern void print_alias_types();
134
135 #endif
136
137 Node *MemNode::optimize_simple_memory_chain(Node *mchain, const TypeOopPtr *t_oop, Node *load, PhaseGVN *phase) {
138 assert((t_oop != NULL), "sanity");
139 bool is_instance = t_oop->is_known_instance_field();
140 bool is_boxed_value_load = t_oop->is_ptr_to_boxed_value() &&
141 (load != NULL) && load->is_Load() &&
142 (phase->is_IterGVN() != NULL);
143 if (!(is_instance || is_boxed_value_load))
144 return mchain; // don't try to optimize non-instance types
145 uint instance_id = t_oop->instance_id();
146 Node *start_mem = phase->C->start()->proj_out_or_null(TypeFunc::Memory);
147 Node *prev = NULL;
148 Node *result = mchain;
149 while (prev != result) {
150 prev = result;
151 if (result == start_mem)
152 break; // hit one of our sentinels
153 // skip over a call which does not affect this memory slice
154 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {
155 Node *proj_in = result->in(0);
156 if (proj_in->is_Allocate() && proj_in->_idx == instance_id) {
157 break; // hit one of our sentinels
158 } else if (proj_in->is_Call()) {
159 // ArrayCopyNodes processed here as well
160 CallNode *call = proj_in->as_Call();
161 if (!call->may_modify(t_oop, phase)) { // returns false for instances
162 result = call->in(TypeFunc::Memory);
163 }
164 } else if (proj_in->is_Initialize()) {
165 AllocateNode* alloc = proj_in->as_Initialize()->allocation();
166 // Stop if this is the initialization for the object instance which
167 // contains this memory slice, otherwise skip over it.
168 if ((alloc == NULL) || (alloc->_idx == instance_id)) {
169 break;
170 }
171 if (is_instance) {
172 result = proj_in->in(TypeFunc::Memory);
173 } else if (is_boxed_value_load) {
174 Node* klass = alloc->in(AllocateNode::KlassNode);
175 const TypeKlassPtr* tklass = phase->type(klass)->is_klassptr();
176 if (tklass->klass_is_exact() && !tklass->klass()->equals(t_oop->klass())) {
177 result = proj_in->in(TypeFunc::Memory); // not related allocation
178 }
179 }
180 } else if (proj_in->is_MemBar()) {
181 ArrayCopyNode* ac = NULL;
182 if (ArrayCopyNode::may_modify(t_oop, proj_in->as_MemBar(), phase, ac)) {
183 break;
184 }
185 result = proj_in->in(TypeFunc::Memory);
186 } else {
187 assert(false, "unexpected projection");
188 }
189 } else if (result->is_ClearArray()) {
190 if (!is_instance || !ClearArrayNode::step_through(&result, instance_id, phase)) {
191 // Can not bypass initialization of the instance
192 // we are looking for.
193 break;
194 }
195 // Otherwise skip it (the call updated 'result' value).
196 } else if (result->is_MergeMem()) {
197 result = step_through_mergemem(phase, result->as_MergeMem(), t_oop, NULL, tty);
198 }
199 }
200 return result;
201 }
202
203 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, Node *load, PhaseGVN *phase) {
204 const TypeOopPtr* t_oop = t_adr->isa_oopptr();
205 if (t_oop == NULL)
206 return mchain; // don't try to optimize non-oop types
207 Node* result = optimize_simple_memory_chain(mchain, t_oop, load, phase);
208 bool is_instance = t_oop->is_known_instance_field();
209 PhaseIterGVN *igvn = phase->is_IterGVN();
210 if (is_instance && igvn != NULL && result->is_Phi()) {
211 PhiNode *mphi = result->as_Phi();
212 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
213 const TypePtr *t = mphi->adr_type();
214 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
215 (t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
216 t->is_oopptr()->cast_to_exactness(true)
217 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
218 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop)) {
219 // clone the Phi with our address type
220 result = mphi->split_out_instance(t_adr, igvn);
221 } else {
222 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain");
223 }
224 }
225 return result;
226 }
227
228 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) {
229 uint alias_idx = phase->C->get_alias_index(tp);
230 Node *mem = mmem;
231 #ifdef ASSERT
232 {
233 // Check that current type is consistent with the alias index used during graph construction
234 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
235 bool consistent = adr_check == NULL || adr_check->empty() ||
236 phase->C->must_alias(adr_check, alias_idx );
237 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
238 if( !consistent && adr_check != NULL && !adr_check->empty() &&
239 tp->isa_aryptr() && tp->offset() == Type::OffsetBot &&
240 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot &&
241 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() ||
242 adr_check->offset() == oopDesc::klass_offset_in_bytes() ||
243 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) {
244 // don't assert if it is dead code.
245 consistent = true;
246 }
247 if( !consistent ) {
248 st->print("alias_idx==%d, adr_check==", alias_idx);
249 if( adr_check == NULL ) {
250 st->print("NULL");
251 } else {
252 adr_check->dump();
253 }
254 st->cr();
255 print_alias_types();
256 assert(consistent, "adr_check must match alias idx");
257 }
258 }
259 #endif
260 // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally
261 // means an array I have not precisely typed yet. Do not do any
262 // alias stuff with it any time soon.
263 const TypeOopPtr *toop = tp->isa_oopptr();
264 if( tp->base() != Type::AnyPtr &&
265 !(toop &&
266 toop->klass() != NULL &&
267 toop->klass()->is_java_lang_Object() &&
268 toop->offset() == Type::OffsetBot) ) {
269 // compress paths and change unreachable cycles to TOP
270 // If not, we can update the input infinitely along a MergeMem cycle
271 // Equivalent code in PhiNode::Ideal
272 Node* m = phase->transform(mmem);
273 // If transformed to a MergeMem, get the desired slice
274 // Otherwise the returned node represents memory for every slice
275 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
276 // Update input if it is progress over what we have now
277 }
278 return mem;
279 }
280
281 //--------------------------Ideal_common---------------------------------------
282 // Look for degenerate control and memory inputs. Bypass MergeMem inputs.
283 // Unhook non-raw memories from complete (macro-expanded) initializations.
284 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
285 // If our control input is a dead region, kill all below the region
286 Node *ctl = in(MemNode::Control);
287 if (ctl && remove_dead_region(phase, can_reshape))
288 return this;
289 ctl = in(MemNode::Control);
290 // Don't bother trying to transform a dead node
291 if (ctl && ctl->is_top()) return NodeSentinel;
292
293 PhaseIterGVN *igvn = phase->is_IterGVN();
294 // Wait if control on the worklist.
295 if (ctl && can_reshape && igvn != NULL) {
296 Node* bol = NULL;
297 Node* cmp = NULL;
298 if (ctl->in(0)->is_If()) {
299 assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity");
300 bol = ctl->in(0)->in(1);
301 if (bol->is_Bool())
302 cmp = ctl->in(0)->in(1)->in(1);
303 }
304 if (igvn->_worklist.member(ctl) ||
305 (bol != NULL && igvn->_worklist.member(bol)) ||
306 (cmp != NULL && igvn->_worklist.member(cmp)) ) {
307 // This control path may be dead.
308 // Delay this memory node transformation until the control is processed.
309 phase->is_IterGVN()->_worklist.push(this);
310 return NodeSentinel; // caller will return NULL
311 }
312 }
313 // Ignore if memory is dead, or self-loop
314 Node *mem = in(MemNode::Memory);
315 if (phase->type( mem ) == Type::TOP) return NodeSentinel; // caller will return NULL
316 assert(mem != this, "dead loop in MemNode::Ideal");
317
318 if (can_reshape && igvn != NULL && igvn->_worklist.member(mem)) {
319 // This memory slice may be dead.
320 // Delay this mem node transformation until the memory is processed.
321 phase->is_IterGVN()->_worklist.push(this);
322 return NodeSentinel; // caller will return NULL
323 }
324
325 Node *address = in(MemNode::Address);
326 const Type *t_adr = phase->type(address);
327 if (t_adr == Type::TOP) return NodeSentinel; // caller will return NULL
328
329 if (can_reshape && igvn != NULL &&
330 (igvn->_worklist.member(address) ||
331 (igvn->_worklist.size() > 0 && t_adr != adr_type())) ) {
332 // The address's base and type may change when the address is processed.
333 // Delay this mem node transformation until the address is processed.
334 phase->is_IterGVN()->_worklist.push(this);
335 return NodeSentinel; // caller will return NULL
336 }
337
338 // Do NOT remove or optimize the next lines: ensure a new alias index
339 // is allocated for an oop pointer type before Escape Analysis.
340 // Note: C++ will not remove it since the call has side effect.
341 if (t_adr->isa_oopptr()) {
342 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr());
343 }
344
345 Node* base = NULL;
346 if (address->is_AddP()) {
347 base = address->in(AddPNode::Base);
348 }
349 if (base != NULL && phase->type(base)->higher_equal(TypePtr::NULL_PTR) &&
350 !t_adr->isa_rawptr()) {
351 // Note: raw address has TOP base and top->higher_equal(TypePtr::NULL_PTR) is true.
352 // Skip this node optimization if its address has TOP base.
353 return NodeSentinel; // caller will return NULL
354 }
355
356 // Avoid independent memory operations
357 Node* old_mem = mem;
358
359 // The code which unhooks non-raw memories from complete (macro-expanded)
360 // initializations was removed. After macro-expansion all stores catched
361 // by Initialize node became raw stores and there is no information
362 // which memory slices they modify. So it is unsafe to move any memory
363 // operation above these stores. Also in most cases hooked non-raw memories
364 // were already unhooked by using information from detect_ptr_independence()
365 // and find_previous_store().
366
367 if (mem->is_MergeMem()) {
368 MergeMemNode* mmem = mem->as_MergeMem();
369 const TypePtr *tp = t_adr->is_ptr();
370
371 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
372 }
373
374 if (mem != old_mem) {
375 set_req(MemNode::Memory, mem);
376 if (can_reshape && old_mem->outcnt() == 0 && igvn != NULL) {
377 igvn->_worklist.push(old_mem);
378 }
379 if (phase->type(mem) == Type::TOP) return NodeSentinel;
380 return this;
381 }
382
383 // let the subclass continue analyzing...
384 return NULL;
385 }
386
387 // Helper function for proving some simple control dominations.
388 // Attempt to prove that all control inputs of 'dom' dominate 'sub'.
389 // Already assumes that 'dom' is available at 'sub', and that 'sub'
390 // is not a constant (dominated by the method's StartNode).
391 // Used by MemNode::find_previous_store to prove that the
392 // control input of a memory operation predates (dominates)
393 // an allocation it wants to look past.
394 bool MemNode::all_controls_dominate(Node* dom, Node* sub) {
395 if (dom == NULL || dom->is_top() || sub == NULL || sub->is_top())
396 return false; // Conservative answer for dead code
397
398 // Check 'dom'. Skip Proj and CatchProj nodes.
399 dom = dom->find_exact_control(dom);
400 if (dom == NULL || dom->is_top())
401 return false; // Conservative answer for dead code
402
403 if (dom == sub) {
404 // For the case when, for example, 'sub' is Initialize and the original
405 // 'dom' is Proj node of the 'sub'.
406 return false;
407 }
408
409 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub)
410 return true;
411
412 // 'dom' dominates 'sub' if its control edge and control edges
413 // of all its inputs dominate or equal to sub's control edge.
414
415 // Currently 'sub' is either Allocate, Initialize or Start nodes.
416 // Or Region for the check in LoadNode::Ideal();
417 // 'sub' should have sub->in(0) != NULL.
418 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() ||
419 sub->is_Region() || sub->is_Call(), "expecting only these nodes");
420
421 // Get control edge of 'sub'.
422 Node* orig_sub = sub;
423 sub = sub->find_exact_control(sub->in(0));
424 if (sub == NULL || sub->is_top())
425 return false; // Conservative answer for dead code
426
427 assert(sub->is_CFG(), "expecting control");
428
429 if (sub == dom)
430 return true;
431
432 if (sub->is_Start() || sub->is_Root())
433 return false;
434
435 {
436 // Check all control edges of 'dom'.
437
438 ResourceMark rm;
439 Arena* arena = Thread::current()->resource_area();
440 Node_List nlist(arena);
441 Unique_Node_List dom_list(arena);
442
443 dom_list.push(dom);
444 bool only_dominating_controls = false;
445
446 for (uint next = 0; next < dom_list.size(); next++) {
447 Node* n = dom_list.at(next);
448 if (n == orig_sub)
449 return false; // One of dom's inputs dominated by sub.
450 if (!n->is_CFG() && n->pinned()) {
451 // Check only own control edge for pinned non-control nodes.
452 n = n->find_exact_control(n->in(0));
453 if (n == NULL || n->is_top())
454 return false; // Conservative answer for dead code
455 assert(n->is_CFG(), "expecting control");
456 dom_list.push(n);
457 } else if (n->is_Con() || n->is_Start() || n->is_Root()) {
458 only_dominating_controls = true;
459 } else if (n->is_CFG()) {
460 if (n->dominates(sub, nlist))
461 only_dominating_controls = true;
462 else
463 return false;
464 } else {
465 // First, own control edge.
466 Node* m = n->find_exact_control(n->in(0));
467 if (m != NULL) {
468 if (m->is_top())
469 return false; // Conservative answer for dead code
470 dom_list.push(m);
471 }
472 // Now, the rest of edges.
473 uint cnt = n->req();
474 for (uint i = 1; i < cnt; i++) {
475 m = n->find_exact_control(n->in(i));
476 if (m == NULL || m->is_top())
477 continue;
478 dom_list.push(m);
479 }
480 }
481 }
482 return only_dominating_controls;
483 }
484 }
485
486 //---------------------detect_ptr_independence---------------------------------
487 // Used by MemNode::find_previous_store to prove that two base
488 // pointers are never equal.
489 // The pointers are accompanied by their associated allocations,
490 // if any, which have been previously discovered by the caller.
491 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
492 Node* p2, AllocateNode* a2,
493 PhaseTransform* phase) {
494 // Attempt to prove that these two pointers cannot be aliased.
495 // They may both manifestly be allocations, and they should differ.
496 // Or, if they are not both allocations, they can be distinct constants.
497 // Otherwise, one is an allocation and the other a pre-existing value.
498 if (a1 == NULL && a2 == NULL) { // neither an allocation
499 return (p1 != p2) && p1->is_Con() && p2->is_Con();
500 } else if (a1 != NULL && a2 != NULL) { // both allocations
501 return (a1 != a2);
502 } else if (a1 != NULL) { // one allocation a1
503 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.)
504 return all_controls_dominate(p2, a1);
505 } else { //(a2 != NULL) // one allocation a2
506 return all_controls_dominate(p1, a2);
507 }
508 return false;
509 }
510
511
512 // Find an arraycopy that must have set (can_see_stored_value=true) or
513 // could have set (can_see_stored_value=false) the value for this load
514 Node* LoadNode::find_previous_arraycopy(PhaseTransform* phase, Node* ld_alloc, Node*& mem, bool can_see_stored_value) const {
515 if (mem->is_Proj() && mem->in(0) != NULL && (mem->in(0)->Opcode() == Op_MemBarStoreStore ||
516 mem->in(0)->Opcode() == Op_MemBarCPUOrder)) {
517 Node* mb = mem->in(0);
518 if (mb->in(0) != NULL && mb->in(0)->is_Proj() &&
519 mb->in(0)->in(0) != NULL && mb->in(0)->in(0)->is_ArrayCopy()) {
520 ArrayCopyNode* ac = mb->in(0)->in(0)->as_ArrayCopy();
521 if (ac->is_clonebasic()) {
522 intptr_t offset;
523 AllocateNode* alloc = AllocateNode::Ideal_allocation(ac->in(ArrayCopyNode::Dest), phase, offset);
524 if (alloc != NULL && alloc == ld_alloc) {
525 return ac;
526 }
527 }
528 }
529 } else if (mem->is_Proj() && mem->in(0) != NULL && mem->in(0)->is_ArrayCopy()) {
530 ArrayCopyNode* ac = mem->in(0)->as_ArrayCopy();
531
532 if (ac->is_arraycopy_validated() ||
533 ac->is_copyof_validated() ||
534 ac->is_copyofrange_validated()) {
535 Node* ld_addp = in(MemNode::Address);
536 if (ld_addp->is_AddP()) {
537 Node* ld_base = ld_addp->in(AddPNode::Address);
538 Node* ld_offs = ld_addp->in(AddPNode::Offset);
539
540 Node* dest = ac->in(ArrayCopyNode::Dest);
541
542 if (dest == ld_base) {
543 const TypeX *ld_offs_t = phase->type(ld_offs)->isa_intptr_t();
544 if (ac->modifies(ld_offs_t->_lo, ld_offs_t->_hi, phase, can_see_stored_value)) {
545 return ac;
546 }
547 if (!can_see_stored_value) {
548 mem = ac->in(TypeFunc::Memory);
549 }
550 }
551 }
552 }
553 }
554 return NULL;
555 }
556
557 // The logic for reordering loads and stores uses four steps:
558 // (a) Walk carefully past stores and initializations which we
559 // can prove are independent of this load.
560 // (b) Observe that the next memory state makes an exact match
561 // with self (load or store), and locate the relevant store.
562 // (c) Ensure that, if we were to wire self directly to the store,
563 // the optimizer would fold it up somehow.
564 // (d) Do the rewiring, and return, depending on some other part of
565 // the optimizer to fold up the load.
566 // This routine handles steps (a) and (b). Steps (c) and (d) are
567 // specific to loads and stores, so they are handled by the callers.
568 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.)
569 //
570 Node* MemNode::find_previous_store(PhaseTransform* phase) {
571 Node* ctrl = in(MemNode::Control);
572 Node* adr = in(MemNode::Address);
573 intptr_t offset = 0;
574 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
575 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase);
576
577 if (offset == Type::OffsetBot)
578 return NULL; // cannot unalias unless there are precise offsets
579
580 const bool adr_maybe_raw = check_if_adr_maybe_raw(adr);
581 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr();
582
583 intptr_t size_in_bytes = memory_size();
584
585 Node* mem = in(MemNode::Memory); // start searching here...
586
587 int cnt = 50; // Cycle limiter
588 for (;;) { // While we can dance past unrelated stores...
589 if (--cnt < 0) break; // Caught in cycle or a complicated dance?
590
591 Node* prev = mem;
592 if (mem->is_Store()) {
593 Node* st_adr = mem->in(MemNode::Address);
594 intptr_t st_offset = 0;
595 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
596 if (st_base == NULL)
597 break; // inscrutable pointer
598
599 // For raw accesses it's not enough to prove that constant offsets don't intersect.
600 // We need the bases to be the equal in order for the offset check to make sense.
601 if ((adr_maybe_raw || check_if_adr_maybe_raw(st_adr)) && st_base != base) {
602 break;
603 }
604
605 if (st_offset != offset && st_offset != Type::OffsetBot) {
606 const int MAX_STORE = BytesPerLong;
607 if (st_offset >= offset + size_in_bytes ||
608 st_offset <= offset - MAX_STORE ||
609 st_offset <= offset - mem->as_Store()->memory_size()) {
610 // Success: The offsets are provably independent.
611 // (You may ask, why not just test st_offset != offset and be done?
612 // The answer is that stores of different sizes can co-exist
613 // in the same sequence of RawMem effects. We sometimes initialize
614 // a whole 'tile' of array elements with a single jint or jlong.)
615 mem = mem->in(MemNode::Memory);
616 continue; // (a) advance through independent store memory
617 }
618 }
619 if (st_base != base &&
620 detect_ptr_independence(base, alloc,
621 st_base,
622 AllocateNode::Ideal_allocation(st_base, phase),
623 phase)) {
624 // Success: The bases are provably independent.
625 mem = mem->in(MemNode::Memory);
626 continue; // (a) advance through independent store memory
627 }
628
629 // (b) At this point, if the bases or offsets do not agree, we lose,
630 // since we have not managed to prove 'this' and 'mem' independent.
631 if (st_base == base && st_offset == offset) {
632 return mem; // let caller handle steps (c), (d)
633 }
634
635 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
636 InitializeNode* st_init = mem->in(0)->as_Initialize();
637 AllocateNode* st_alloc = st_init->allocation();
638 if (st_alloc == NULL)
639 break; // something degenerated
640 bool known_identical = false;
641 bool known_independent = false;
642 if (alloc == st_alloc)
643 known_identical = true;
644 else if (alloc != NULL)
645 known_independent = true;
646 else if (all_controls_dominate(this, st_alloc))
647 known_independent = true;
648
649 if (known_independent) {
650 // The bases are provably independent: Either they are
651 // manifestly distinct allocations, or else the control
652 // of this load dominates the store's allocation.
653 int alias_idx = phase->C->get_alias_index(adr_type());
654 if (alias_idx == Compile::AliasIdxRaw) {
655 mem = st_alloc->in(TypeFunc::Memory);
656 } else {
657 mem = st_init->memory(alias_idx);
658 }
659 continue; // (a) advance through independent store memory
660 }
661
662 // (b) at this point, if we are not looking at a store initializing
663 // the same allocation we are loading from, we lose.
664 if (known_identical) {
665 // From caller, can_see_stored_value will consult find_captured_store.
666 return mem; // let caller handle steps (c), (d)
667 }
668
669 } else if (find_previous_arraycopy(phase, alloc, mem, false) != NULL) {
670 if (prev != mem) {
671 // Found an arraycopy but it doesn't affect that load
672 continue;
673 }
674 // Found an arraycopy that may affect that load
675 return mem;
676 } else if (addr_t != NULL && addr_t->is_known_instance_field()) {
677 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
678 if (mem->is_Proj() && mem->in(0)->is_Call()) {
679 // ArrayCopyNodes processed here as well.
680 CallNode *call = mem->in(0)->as_Call();
681 if (!call->may_modify(addr_t, phase)) {
682 mem = call->in(TypeFunc::Memory);
683 continue; // (a) advance through independent call memory
684 }
685 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) {
686 ArrayCopyNode* ac = NULL;
687 if (ArrayCopyNode::may_modify(addr_t, mem->in(0)->as_MemBar(), phase, ac)) {
688 break;
689 }
690 mem = mem->in(0)->in(TypeFunc::Memory);
691 continue; // (a) advance through independent MemBar memory
692 } else if (mem->is_ClearArray()) {
693 if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) {
694 // (the call updated 'mem' value)
695 continue; // (a) advance through independent allocation memory
696 } else {
697 // Can not bypass initialization of the instance
698 // we are looking for.
699 return mem;
700 }
701 } else if (mem->is_MergeMem()) {
702 int alias_idx = phase->C->get_alias_index(adr_type());
703 mem = mem->as_MergeMem()->memory_at(alias_idx);
704 continue; // (a) advance through independent MergeMem memory
705 }
706 }
707
708 // Unless there is an explicit 'continue', we must bail out here,
709 // because 'mem' is an inscrutable memory state (e.g., a call).
710 break;
711 }
712
713 return NULL; // bail out
714 }
715
716 //----------------------calculate_adr_type-------------------------------------
717 // Helper function. Notices when the given type of address hits top or bottom.
718 // Also, asserts a cross-check of the type against the expected address type.
719 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
720 if (t == Type::TOP) return NULL; // does not touch memory any more?
721 #ifdef PRODUCT
722 cross_check = NULL;
723 #else
724 if (!VerifyAliases || VMError::is_error_reported() || Node::in_dump()) cross_check = NULL;
725 #endif
726 const TypePtr* tp = t->isa_ptr();
727 if (tp == NULL) {
728 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
729 return TypePtr::BOTTOM; // touches lots of memory
730 } else {
731 #ifdef ASSERT
732 // %%%% [phh] We don't check the alias index if cross_check is
733 // TypeRawPtr::BOTTOM. Needs to be investigated.
734 if (cross_check != NULL &&
735 cross_check != TypePtr::BOTTOM &&
736 cross_check != TypeRawPtr::BOTTOM) {
737 // Recheck the alias index, to see if it has changed (due to a bug).
738 Compile* C = Compile::current();
739 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
740 "must stay in the original alias category");
741 // The type of the address must be contained in the adr_type,
742 // disregarding "null"-ness.
743 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
744 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
745 assert(cross_check->meet(tp_notnull) == cross_check->remove_speculative(),
746 "real address must not escape from expected memory type");
747 }
748 #endif
749 return tp;
750 }
751 }
752
753 //=============================================================================
754 // Should LoadNode::Ideal() attempt to remove control edges?
755 bool LoadNode::can_remove_control() const {
756 return true;
757 }
758 uint LoadNode::size_of() const { return sizeof(*this); }
759 uint LoadNode::cmp( const Node &n ) const
760 { return !Type::cmp( _type, ((LoadNode&)n)._type ); }
761 const Type *LoadNode::bottom_type() const { return _type; }
762 uint LoadNode::ideal_reg() const {
763 return _type->ideal_reg();
764 }
765
766 #ifndef PRODUCT
767 void LoadNode::dump_spec(outputStream *st) const {
768 MemNode::dump_spec(st);
769 if( !Verbose && !WizardMode ) {
770 // standard dump does this in Verbose and WizardMode
771 st->print(" #"); _type->dump_on(st);
772 }
773 if (!depends_only_on_test()) {
774 st->print(" (does not depend only on test)");
775 }
776 }
777 #endif
778
779 #ifdef ASSERT
780 //----------------------------is_immutable_value-------------------------------
781 // Helper function to allow a raw load without control edge for some cases
782 bool LoadNode::is_immutable_value(Node* adr) {
783 return (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() &&
784 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal &&
785 (adr->in(AddPNode::Offset)->find_intptr_t_con(-1) ==
786 in_bytes(JavaThread::osthread_offset())));
787 }
788 #endif
789
790 //----------------------------LoadNode::make-----------------------------------
791 // Polymorphic factory method:
792 Node *LoadNode::make(PhaseGVN& gvn, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt, MemOrd mo,
793 ControlDependency control_dependency, bool unaligned, bool mismatched) {
794 Compile* C = gvn.C;
795
796 // sanity check the alias category against the created node type
797 assert(!(adr_type->isa_oopptr() &&
798 adr_type->offset() == oopDesc::klass_offset_in_bytes()),
799 "use LoadKlassNode instead");
800 assert(!(adr_type->isa_aryptr() &&
801 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
802 "use LoadRangeNode instead");
803 // Check control edge of raw loads
804 assert( ctl != NULL || C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
805 // oop will be recorded in oop map if load crosses safepoint
806 rt->isa_oopptr() || is_immutable_value(adr),
807 "raw memory operations should have control edge");
808 LoadNode* load = NULL;
809 switch (bt) {
810 case T_BOOLEAN: load = new LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
811 case T_BYTE: load = new LoadBNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
812 case T_INT: load = new LoadINode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
813 case T_CHAR: load = new LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
814 case T_SHORT: load = new LoadSNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
815 case T_LONG: load = new LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency); break;
816 case T_FLOAT: load = new LoadFNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); break;
817 case T_DOUBLE: load = new LoadDNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); break;
818 case T_ADDRESS: load = new LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency); break;
819 case T_VALUETYPE:
820 case T_OBJECT:
821 #ifdef _LP64
822 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
823 load = new LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo, control_dependency);
824 } else
825 #endif
826 {
827 assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop");
828 load = new LoadPNode(ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency);
829 }
830 break;
831 default:
832 ShouldNotReachHere();
833 break;
834 }
835 assert(load != NULL, "LoadNode should have been created");
836 if (unaligned) {
837 load->set_unaligned_access();
838 }
839 if (mismatched) {
840 load->set_mismatched_access();
841 }
842 if (load->Opcode() == Op_LoadN) {
843 Node* ld = gvn.transform(load);
844 return new DecodeNNode(ld, ld->bottom_type()->make_ptr());
845 }
846
847 return load;
848 }
849
850 LoadLNode* LoadLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo,
851 ControlDependency control_dependency, bool unaligned, bool mismatched) {
852 bool require_atomic = true;
853 LoadLNode* load = new LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency, require_atomic);
854 if (unaligned) {
855 load->set_unaligned_access();
856 }
857 if (mismatched) {
858 load->set_mismatched_access();
859 }
860 return load;
861 }
862
863 LoadDNode* LoadDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo,
864 ControlDependency control_dependency, bool unaligned, bool mismatched) {
865 bool require_atomic = true;
866 LoadDNode* load = new LoadDNode(ctl, mem, adr, adr_type, rt, mo, control_dependency, require_atomic);
867 if (unaligned) {
868 load->set_unaligned_access();
869 }
870 if (mismatched) {
871 load->set_mismatched_access();
872 }
873 return load;
874 }
875
876
877
878 //------------------------------hash-------------------------------------------
879 uint LoadNode::hash() const {
880 // unroll addition of interesting fields
881 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
882 }
883
884 static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) {
885 if ((atp != NULL) && (atp->index() >= Compile::AliasIdxRaw)) {
886 bool non_volatile = (atp->field() != NULL) && !atp->field()->is_volatile();
887 bool is_stable_ary = FoldStableValues &&
888 (tp != NULL) && (tp->isa_aryptr() != NULL) &&
889 tp->isa_aryptr()->is_stable();
890
891 return (eliminate_boxing && non_volatile) || is_stable_ary;
892 }
893
894 return false;
895 }
896
897 // Is the value loaded previously stored by an arraycopy? If so return
898 // a load node that reads from the source array so we may be able to
899 // optimize out the ArrayCopy node later.
900 Node* LoadNode::can_see_arraycopy_value(Node* st, PhaseGVN* phase) const {
901 #if INCLUDE_ZGC
902 if (UseZGC) {
903 if (bottom_type()->make_oopptr() != NULL) {
904 return NULL;
905 }
906 }
907 #endif
908
909 Node* ld_adr = in(MemNode::Address);
910 intptr_t ld_off = 0;
911 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
912 Node* ac = find_previous_arraycopy(phase, ld_alloc, st, true);
913 if (ac != NULL) {
914 assert(ac->is_ArrayCopy(), "what kind of node can this be?");
915
916 Node* mem = ac->in(TypeFunc::Memory);
917 Node* ctl = ac->in(0);
918 Node* src = ac->in(ArrayCopyNode::Src);
919
920 if (!ac->as_ArrayCopy()->is_clonebasic() && !phase->type(src)->isa_aryptr()) {
921 return NULL;
922 }
923
924 LoadNode* ld = clone()->as_Load();
925 Node* addp = in(MemNode::Address)->clone();
926 if (ac->as_ArrayCopy()->is_clonebasic()) {
927 assert(ld_alloc != NULL, "need an alloc");
928 assert(addp->is_AddP(), "address must be addp");
929 assert(ac->in(ArrayCopyNode::Dest)->is_AddP(), "dest must be an address");
930 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
931 assert(bs->step_over_gc_barrier(addp->in(AddPNode::Base)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)->in(AddPNode::Base)), "strange pattern");
932 assert(bs->step_over_gc_barrier(addp->in(AddPNode::Address)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)->in(AddPNode::Address)), "strange pattern");
933 addp->set_req(AddPNode::Base, src->in(AddPNode::Base));
934 addp->set_req(AddPNode::Address, src->in(AddPNode::Address));
935 } else {
936 assert(ac->as_ArrayCopy()->is_arraycopy_validated() ||
937 ac->as_ArrayCopy()->is_copyof_validated() ||
938 ac->as_ArrayCopy()->is_copyofrange_validated(), "only supported cases");
939 assert(addp->in(AddPNode::Base) == addp->in(AddPNode::Address), "should be");
940 addp->set_req(AddPNode::Base, src);
941 addp->set_req(AddPNode::Address, src);
942
943 const TypeAryPtr* ary_t = phase->type(in(MemNode::Address))->isa_aryptr();
944 BasicType ary_elem = ary_t->klass()->as_array_klass()->element_type()->basic_type();
945 uint header = arrayOopDesc::base_offset_in_bytes(ary_elem);
946 uint shift = exact_log2(type2aelembytes(ary_elem));
947
948 Node* diff = phase->transform(new SubINode(ac->in(ArrayCopyNode::SrcPos), ac->in(ArrayCopyNode::DestPos)));
949 #ifdef _LP64
950 diff = phase->transform(new ConvI2LNode(diff));
951 #endif
952 diff = phase->transform(new LShiftXNode(diff, phase->intcon(shift)));
953
954 Node* offset = phase->transform(new AddXNode(addp->in(AddPNode::Offset), diff));
955 addp->set_req(AddPNode::Offset, offset);
956 }
957 addp = phase->transform(addp);
958 #ifdef ASSERT
959 const TypePtr* adr_type = phase->type(addp)->is_ptr();
960 ld->_adr_type = adr_type;
961 #endif
962 ld->set_req(MemNode::Address, addp);
963 ld->set_req(0, ctl);
964 ld->set_req(MemNode::Memory, mem);
965 // load depends on the tests that validate the arraycopy
966 ld->_control_dependency = Pinned;
967 return ld;
968 }
969 return NULL;
970 }
971
972
973 //---------------------------can_see_stored_value------------------------------
974 // This routine exists to make sure this set of tests is done the same
975 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
976 // will change the graph shape in a way which makes memory alive twice at the
977 // same time (uses the Oracle model of aliasing), then some
978 // LoadXNode::Identity will fold things back to the equivalence-class model
979 // of aliasing.
980 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const {
981 Node* ld_adr = in(MemNode::Address);
982 intptr_t ld_off = 0;
983 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
984 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
985 Compile::AliasType* atp = (tp != NULL) ? phase->C->alias_type(tp) : NULL;
986 // This is more general than load from boxing objects.
987 if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) {
988 uint alias_idx = atp->index();
989 bool final = !atp->is_rewritable();
990 Node* result = NULL;
991 Node* current = st;
992 // Skip through chains of MemBarNodes checking the MergeMems for
993 // new states for the slice of this load. Stop once any other
994 // kind of node is encountered. Loads from final memory can skip
995 // through any kind of MemBar but normal loads shouldn't skip
996 // through MemBarAcquire since the could allow them to move out of
997 // a synchronized region.
998 while (current->is_Proj()) {
999 int opc = current->in(0)->Opcode();
1000 if ((final && (opc == Op_MemBarAcquire ||
1001 opc == Op_MemBarAcquireLock ||
1002 opc == Op_LoadFence)) ||
1003 opc == Op_MemBarRelease ||
1004 opc == Op_StoreFence ||
1005 opc == Op_MemBarReleaseLock ||
1006 opc == Op_MemBarStoreStore ||
1007 opc == Op_MemBarCPUOrder) {
1008 Node* mem = current->in(0)->in(TypeFunc::Memory);
1009 if (mem->is_MergeMem()) {
1010 MergeMemNode* merge = mem->as_MergeMem();
1011 Node* new_st = merge->memory_at(alias_idx);
1012 if (new_st == merge->base_memory()) {
1013 // Keep searching
1014 current = new_st;
1015 continue;
1016 }
1017 // Save the new memory state for the slice and fall through
1018 // to exit.
1019 result = new_st;
1020 }
1021 }
1022 break;
1023 }
1024 if (result != NULL) {
1025 st = result;
1026 }
1027 }
1028
1029 // Loop around twice in the case Load -> Initialize -> Store.
1030 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
1031 for (int trip = 0; trip <= 1; trip++) {
1032
1033 if (st->is_Store()) {
1034 Node* st_adr = st->in(MemNode::Address);
1035 if (!phase->eqv(st_adr, ld_adr)) {
1036 // Try harder before giving up... Match raw and non-raw pointers.
1037 intptr_t st_off = 0;
1038 AllocateNode* alloc = AllocateNode::Ideal_allocation(st_adr, phase, st_off);
1039 if (alloc == NULL) return NULL;
1040 if (alloc != ld_alloc) return NULL;
1041 if (ld_off != st_off) return NULL;
1042 // At this point we have proven something like this setup:
1043 // A = Allocate(...)
1044 // L = LoadQ(, AddP(CastPP(, A.Parm),, #Off))
1045 // S = StoreQ(, AddP(, A.Parm , #Off), V)
1046 // (Actually, we haven't yet proven the Q's are the same.)
1047 // In other words, we are loading from a casted version of
1048 // the same pointer-and-offset that we stored to.
1049 // Thus, we are able to replace L by V.
1050 }
1051 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
1052 if (store_Opcode() != st->Opcode())
1053 return NULL;
1054 return st->in(MemNode::ValueIn);
1055 }
1056
1057 // A load from a freshly-created object always returns zero.
1058 // (This can happen after LoadNode::Ideal resets the load's memory input
1059 // to find_captured_store, which returned InitializeNode::zero_memory.)
1060 if (st->is_Proj() && st->in(0)->is_Allocate() &&
1061 (st->in(0) == ld_alloc) &&
1062 (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) {
1063 // return a zero value for the load's basic type
1064 // (This is one of the few places where a generic PhaseTransform
1065 // can create new nodes. Think of it as lazily manifesting
1066 // virtually pre-existing constants.)
1067 assert(memory_type() != T_VALUETYPE, "should not be used for value types");
1068 Node* default_value = ld_alloc->in(AllocateNode::DefaultValue);
1069 if (default_value != NULL) {
1070 return default_value;
1071 }
1072 assert(ld_alloc->in(AllocateNode::RawDefaultValue) == NULL, "default value may not be null");
1073 return phase->zerocon(memory_type());
1074 }
1075
1076 // A load from an initialization barrier can match a captured store.
1077 if (st->is_Proj() && st->in(0)->is_Initialize()) {
1078 InitializeNode* init = st->in(0)->as_Initialize();
1079 AllocateNode* alloc = init->allocation();
1080 if ((alloc != NULL) && (alloc == ld_alloc)) {
1081 // examine a captured store value
1082 st = init->find_captured_store(ld_off, memory_size(), phase);
1083 if (st != NULL) {
1084 continue; // take one more trip around
1085 }
1086 }
1087 }
1088
1089 // Load boxed value from result of valueOf() call is input parameter.
1090 if (this->is_Load() && ld_adr->is_AddP() &&
1091 (tp != NULL) && tp->is_ptr_to_boxed_value()) {
1092 intptr_t ignore = 0;
1093 Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore);
1094 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1095 base = bs->step_over_gc_barrier(base);
1096 if (base != NULL && base->is_Proj() &&
1097 base->as_Proj()->_con == TypeFunc::Parms &&
1098 base->in(0)->is_CallStaticJava() &&
1099 base->in(0)->as_CallStaticJava()->is_boxing_method()) {
1100 return base->in(0)->in(TypeFunc::Parms);
1101 }
1102 }
1103
1104 break;
1105 }
1106
1107 return NULL;
1108 }
1109
1110 //----------------------is_instance_field_load_with_local_phi------------------
1111 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
1112 if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl &&
1113 in(Address)->is_AddP() ) {
1114 const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr();
1115 // Only instances and boxed values.
1116 if( t_oop != NULL &&
1117 (t_oop->is_ptr_to_boxed_value() ||
1118 t_oop->is_known_instance_field()) &&
1119 t_oop->offset() != Type::OffsetBot &&
1120 t_oop->offset() != Type::OffsetTop) {
1121 return true;
1122 }
1123 }
1124 return false;
1125 }
1126
1127 //------------------------------Identity---------------------------------------
1128 // Loads are identity if previous store is to same address
1129 Node* LoadNode::Identity(PhaseGVN* phase) {
1130 // Loading from a ValueTypePtr? The ValueTypePtr has the values of
1131 // all fields as input. Look for the field with matching offset.
1132 Node* addr = in(Address);
1133 intptr_t offset;
1134 Node* base = AddPNode::Ideal_base_and_offset(addr, phase, offset);
1135 if (base != NULL && base->is_ValueTypePtr() && offset > oopDesc::klass_offset_in_bytes()) {
1136 Node* value = base->as_ValueTypePtr()->field_value_by_offset((int)offset, true);
1137 if (value->is_ValueType()) {
1138 // Non-flattened value type field
1139 ValueTypeNode* vt = value->as_ValueType();
1140 if (vt->is_allocated(phase)) {
1141 value = vt->get_oop();
1142 } else {
1143 // Not yet allocated, bail out
1144 value = NULL;
1145 }
1146 }
1147 if (value != NULL) {
1148 if (Opcode() == Op_LoadN) {
1149 // Encode oop value if we are loading a narrow oop
1150 assert(!phase->type(value)->isa_narrowoop(), "should already be decoded");
1151 value = phase->transform(new EncodePNode(value, bottom_type()));
1152 }
1153 return value;
1154 }
1155 }
1156
1157 // If the previous store-maker is the right kind of Store, and the store is
1158 // to the same address, then we are equal to the value stored.
1159 Node* mem = in(Memory);
1160 Node* value = can_see_stored_value(mem, phase);
1161 if( value ) {
1162 // byte, short & char stores truncate naturally.
1163 // A load has to load the truncated value which requires
1164 // some sort of masking operation and that requires an
1165 // Ideal call instead of an Identity call.
1166 if (memory_size() < BytesPerInt) {
1167 // If the input to the store does not fit with the load's result type,
1168 // it must be truncated via an Ideal call.
1169 if (!phase->type(value)->higher_equal(phase->type(this)))
1170 return this;
1171 }
1172 // (This works even when value is a Con, but LoadNode::Value
1173 // usually runs first, producing the singleton type of the Con.)
1174 return value;
1175 }
1176
1177 // Search for an existing data phi which was generated before for the same
1178 // instance's field to avoid infinite generation of phis in a loop.
1179 Node *region = mem->in(0);
1180 if (is_instance_field_load_with_local_phi(region)) {
1181 const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr();
1182 int this_index = phase->C->get_alias_index(addr_t);
1183 int this_offset = addr_t->offset();
1184 int this_iid = addr_t->instance_id();
1185 if (!addr_t->is_known_instance() &&
1186 addr_t->is_ptr_to_boxed_value()) {
1187 // Use _idx of address base (could be Phi node) for boxed values.
1188 intptr_t ignore = 0;
1189 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1190 if (base == NULL) {
1191 return this;
1192 }
1193 this_iid = base->_idx;
1194 }
1195 const Type* this_type = bottom_type();
1196 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1197 Node* phi = region->fast_out(i);
1198 if (phi->is_Phi() && phi != mem &&
1199 phi->as_Phi()->is_same_inst_field(this_type, (int)mem->_idx, this_iid, this_index, this_offset)) {
1200 return phi;
1201 }
1202 }
1203 }
1204
1205 return this;
1206 }
1207
1208 // Construct an equivalent unsigned load.
1209 Node* LoadNode::convert_to_unsigned_load(PhaseGVN& gvn) {
1210 BasicType bt = T_ILLEGAL;
1211 const Type* rt = NULL;
1212 switch (Opcode()) {
1213 case Op_LoadUB: return this;
1214 case Op_LoadUS: return this;
1215 case Op_LoadB: bt = T_BOOLEAN; rt = TypeInt::UBYTE; break;
1216 case Op_LoadS: bt = T_CHAR; rt = TypeInt::CHAR; break;
1217 default:
1218 assert(false, "no unsigned variant: %s", Name());
1219 return NULL;
1220 }
1221 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1222 raw_adr_type(), rt, bt, _mo, _control_dependency,
1223 is_unaligned_access(), is_mismatched_access());
1224 }
1225
1226 // Construct an equivalent signed load.
1227 Node* LoadNode::convert_to_signed_load(PhaseGVN& gvn) {
1228 BasicType bt = T_ILLEGAL;
1229 const Type* rt = NULL;
1230 switch (Opcode()) {
1231 case Op_LoadUB: bt = T_BYTE; rt = TypeInt::BYTE; break;
1232 case Op_LoadUS: bt = T_SHORT; rt = TypeInt::SHORT; break;
1233 case Op_LoadB: // fall through
1234 case Op_LoadS: // fall through
1235 case Op_LoadI: // fall through
1236 case Op_LoadL: return this;
1237 default:
1238 assert(false, "no signed variant: %s", Name());
1239 return NULL;
1240 }
1241 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1242 raw_adr_type(), rt, bt, _mo, _control_dependency,
1243 is_unaligned_access(), is_mismatched_access());
1244 }
1245
1246 // We're loading from an object which has autobox behaviour.
1247 // If this object is result of a valueOf call we'll have a phi
1248 // merging a newly allocated object and a load from the cache.
1249 // We want to replace this load with the original incoming
1250 // argument to the valueOf call.
1251 Node* LoadNode::eliminate_autobox(PhaseGVN* phase) {
1252 assert(phase->C->eliminate_boxing(), "sanity");
1253 intptr_t ignore = 0;
1254 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1255 if ((base == NULL) || base->is_Phi()) {
1256 // Push the loads from the phi that comes from valueOf up
1257 // through it to allow elimination of the loads and the recovery
1258 // of the original value. It is done in split_through_phi().
1259 return NULL;
1260 } else if (base->is_Load() ||
1261 (base->is_DecodeN() && base->in(1)->is_Load())) {
1262 // Eliminate the load of boxed value for integer types from the cache
1263 // array by deriving the value from the index into the array.
1264 // Capture the offset of the load and then reverse the computation.
1265
1266 // Get LoadN node which loads a boxing object from 'cache' array.
1267 if (base->is_DecodeN()) {
1268 base = base->in(1);
1269 }
1270 if (!base->in(Address)->is_AddP()) {
1271 return NULL; // Complex address
1272 }
1273 AddPNode* address = base->in(Address)->as_AddP();
1274 Node* cache_base = address->in(AddPNode::Base);
1275 if ((cache_base != NULL) && cache_base->is_DecodeN()) {
1276 // Get ConP node which is static 'cache' field.
1277 cache_base = cache_base->in(1);
1278 }
1279 if ((cache_base != NULL) && cache_base->is_Con()) {
1280 const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr();
1281 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1282 Node* elements[4];
1283 int shift = exact_log2(type2aelembytes(T_OBJECT));
1284 int count = address->unpack_offsets(elements, ARRAY_SIZE(elements));
1285 if (count > 0 && elements[0]->is_Con() &&
1286 (count == 1 ||
1287 (count == 2 && elements[1]->Opcode() == Op_LShiftX &&
1288 elements[1]->in(2) == phase->intcon(shift)))) {
1289 ciObjArray* array = base_type->const_oop()->as_obj_array();
1290 // Fetch the box object cache[0] at the base of the array and get its value
1291 ciInstance* box = array->obj_at(0)->as_instance();
1292 ciInstanceKlass* ik = box->klass()->as_instance_klass();
1293 assert(ik->is_box_klass(), "sanity");
1294 assert(ik->nof_nonstatic_fields() == 1, "change following code");
1295 if (ik->nof_nonstatic_fields() == 1) {
1296 // This should be true nonstatic_field_at requires calling
1297 // nof_nonstatic_fields so check it anyway
1298 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1299 BasicType bt = c.basic_type();
1300 // Only integer types have boxing cache.
1301 assert(bt == T_BOOLEAN || bt == T_CHAR ||
1302 bt == T_BYTE || bt == T_SHORT ||
1303 bt == T_INT || bt == T_LONG, "wrong type = %s", type2name(bt));
1304 jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int();
1305 if (cache_low != (int)cache_low) {
1306 return NULL; // should not happen since cache is array indexed by value
1307 }
1308 jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift);
1309 if (offset != (int)offset) {
1310 return NULL; // should not happen since cache is array indexed by value
1311 }
1312 // Add up all the offsets making of the address of the load
1313 Node* result = elements[0];
1314 for (int i = 1; i < count; i++) {
1315 result = phase->transform(new AddXNode(result, elements[i]));
1316 }
1317 // Remove the constant offset from the address and then
1318 result = phase->transform(new AddXNode(result, phase->MakeConX(-(int)offset)));
1319 // remove the scaling of the offset to recover the original index.
1320 if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) {
1321 // Peel the shift off directly but wrap it in a dummy node
1322 // since Ideal can't return existing nodes
1323 result = new RShiftXNode(result->in(1), phase->intcon(0));
1324 } else if (result->is_Add() && result->in(2)->is_Con() &&
1325 result->in(1)->Opcode() == Op_LShiftX &&
1326 result->in(1)->in(2) == phase->intcon(shift)) {
1327 // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z)
1328 // but for boxing cache access we know that X<<Z will not overflow
1329 // (there is range check) so we do this optimizatrion by hand here.
1330 Node* add_con = new RShiftXNode(result->in(2), phase->intcon(shift));
1331 result = new AddXNode(result->in(1)->in(1), phase->transform(add_con));
1332 } else {
1333 result = new RShiftXNode(result, phase->intcon(shift));
1334 }
1335 #ifdef _LP64
1336 if (bt != T_LONG) {
1337 result = new ConvL2INode(phase->transform(result));
1338 }
1339 #else
1340 if (bt == T_LONG) {
1341 result = new ConvI2LNode(phase->transform(result));
1342 }
1343 #endif
1344 // Boxing/unboxing can be done from signed & unsigned loads (e.g. LoadUB -> ... -> LoadB pair).
1345 // Need to preserve unboxing load type if it is unsigned.
1346 switch(this->Opcode()) {
1347 case Op_LoadUB:
1348 result = new AndINode(phase->transform(result), phase->intcon(0xFF));
1349 break;
1350 case Op_LoadUS:
1351 result = new AndINode(phase->transform(result), phase->intcon(0xFFFF));
1352 break;
1353 }
1354 return result;
1355 }
1356 }
1357 }
1358 }
1359 }
1360 return NULL;
1361 }
1362
1363 static bool stable_phi(PhiNode* phi, PhaseGVN *phase) {
1364 Node* region = phi->in(0);
1365 if (region == NULL) {
1366 return false; // Wait stable graph
1367 }
1368 uint cnt = phi->req();
1369 for (uint i = 1; i < cnt; i++) {
1370 Node* rc = region->in(i);
1371 if (rc == NULL || phase->type(rc) == Type::TOP)
1372 return false; // Wait stable graph
1373 Node* in = phi->in(i);
1374 if (in == NULL || phase->type(in) == Type::TOP)
1375 return false; // Wait stable graph
1376 }
1377 return true;
1378 }
1379 //------------------------------split_through_phi------------------------------
1380 // Split instance or boxed field load through Phi.
1381 Node *LoadNode::split_through_phi(PhaseGVN *phase) {
1382 Node* mem = in(Memory);
1383 Node* address = in(Address);
1384 const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr();
1385
1386 assert((t_oop != NULL) &&
1387 (t_oop->is_known_instance_field() ||
1388 t_oop->is_ptr_to_boxed_value()), "invalide conditions");
1389
1390 Compile* C = phase->C;
1391 intptr_t ignore = 0;
1392 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1393 bool base_is_phi = (base != NULL) && base->is_Phi();
1394 bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() &&
1395 (base != NULL) && (base == address->in(AddPNode::Base)) &&
1396 phase->type(base)->higher_equal(TypePtr::NOTNULL);
1397
1398 if (!((mem->is_Phi() || base_is_phi) &&
1399 (load_boxed_values || t_oop->is_known_instance_field()))) {
1400 return NULL; // memory is not Phi
1401 }
1402
1403 if (mem->is_Phi()) {
1404 if (!stable_phi(mem->as_Phi(), phase)) {
1405 return NULL; // Wait stable graph
1406 }
1407 uint cnt = mem->req();
1408 // Check for loop invariant memory.
1409 if (cnt == 3) {
1410 for (uint i = 1; i < cnt; i++) {
1411 Node* in = mem->in(i);
1412 Node* m = optimize_memory_chain(in, t_oop, this, phase);
1413 if (m == mem) {
1414 set_req(Memory, mem->in(cnt - i));
1415 return this; // made change
1416 }
1417 }
1418 }
1419 }
1420 if (base_is_phi) {
1421 if (!stable_phi(base->as_Phi(), phase)) {
1422 return NULL; // Wait stable graph
1423 }
1424 uint cnt = base->req();
1425 // Check for loop invariant memory.
1426 if (cnt == 3) {
1427 for (uint i = 1; i < cnt; i++) {
1428 if (base->in(i) == base) {
1429 return NULL; // Wait stable graph
1430 }
1431 }
1432 }
1433 }
1434
1435 bool load_boxed_phi = load_boxed_values && base_is_phi && (base->in(0) == mem->in(0));
1436
1437 // Split through Phi (see original code in loopopts.cpp).
1438 assert(C->have_alias_type(t_oop), "instance should have alias type");
1439
1440 // Do nothing here if Identity will find a value
1441 // (to avoid infinite chain of value phis generation).
1442 if (!phase->eqv(this, phase->apply_identity(this)))
1443 return NULL;
1444
1445 // Select Region to split through.
1446 Node* region;
1447 if (!base_is_phi) {
1448 assert(mem->is_Phi(), "sanity");
1449 region = mem->in(0);
1450 // Skip if the region dominates some control edge of the address.
1451 if (!MemNode::all_controls_dominate(address, region))
1452 return NULL;
1453 } else if (!mem->is_Phi()) {
1454 assert(base_is_phi, "sanity");
1455 region = base->in(0);
1456 // Skip if the region dominates some control edge of the memory.
1457 if (!MemNode::all_controls_dominate(mem, region))
1458 return NULL;
1459 } else if (base->in(0) != mem->in(0)) {
1460 assert(base_is_phi && mem->is_Phi(), "sanity");
1461 if (MemNode::all_controls_dominate(mem, base->in(0))) {
1462 region = base->in(0);
1463 } else if (MemNode::all_controls_dominate(address, mem->in(0))) {
1464 region = mem->in(0);
1465 } else {
1466 return NULL; // complex graph
1467 }
1468 } else {
1469 assert(base->in(0) == mem->in(0), "sanity");
1470 region = mem->in(0);
1471 }
1472
1473 const Type* this_type = this->bottom_type();
1474 int this_index = C->get_alias_index(t_oop);
1475 int this_offset = t_oop->offset();
1476 int this_iid = t_oop->instance_id();
1477 if (!t_oop->is_known_instance() && load_boxed_values) {
1478 // Use _idx of address base for boxed values.
1479 this_iid = base->_idx;
1480 }
1481 PhaseIterGVN* igvn = phase->is_IterGVN();
1482 Node* phi = new PhiNode(region, this_type, NULL, mem->_idx, this_iid, this_index, this_offset);
1483 for (uint i = 1; i < region->req(); i++) {
1484 Node* x;
1485 Node* the_clone = NULL;
1486 if (region->in(i) == C->top()) {
1487 x = C->top(); // Dead path? Use a dead data op
1488 } else {
1489 x = this->clone(); // Else clone up the data op
1490 the_clone = x; // Remember for possible deletion.
1491 // Alter data node to use pre-phi inputs
1492 if (this->in(0) == region) {
1493 x->set_req(0, region->in(i));
1494 } else {
1495 x->set_req(0, NULL);
1496 }
1497 if (mem->is_Phi() && (mem->in(0) == region)) {
1498 x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone.
1499 }
1500 if (address->is_Phi() && address->in(0) == region) {
1501 x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone
1502 }
1503 if (base_is_phi && (base->in(0) == region)) {
1504 Node* base_x = base->in(i); // Clone address for loads from boxed objects.
1505 Node* adr_x = phase->transform(new AddPNode(base_x,base_x,address->in(AddPNode::Offset)));
1506 x->set_req(Address, adr_x);
1507 }
1508 }
1509 // Check for a 'win' on some paths
1510 const Type *t = x->Value(igvn);
1511
1512 bool singleton = t->singleton();
1513
1514 // See comments in PhaseIdealLoop::split_thru_phi().
1515 if (singleton && t == Type::TOP) {
1516 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1517 }
1518
1519 if (singleton) {
1520 x = igvn->makecon(t);
1521 } else {
1522 // We now call Identity to try to simplify the cloned node.
1523 // Note that some Identity methods call phase->type(this).
1524 // Make sure that the type array is big enough for
1525 // our new node, even though we may throw the node away.
1526 // (This tweaking with igvn only works because x is a new node.)
1527 igvn->set_type(x, t);
1528 // If x is a TypeNode, capture any more-precise type permanently into Node
1529 // otherwise it will be not updated during igvn->transform since
1530 // igvn->type(x) is set to x->Value() already.
1531 x->raise_bottom_type(t);
1532 Node *y = igvn->apply_identity(x);
1533 if (y != x) {
1534 x = y;
1535 } else {
1536 y = igvn->hash_find_insert(x);
1537 if (y) {
1538 x = y;
1539 } else {
1540 // Else x is a new node we are keeping
1541 // We do not need register_new_node_with_optimizer
1542 // because set_type has already been called.
1543 igvn->_worklist.push(x);
1544 }
1545 }
1546 }
1547 if (x != the_clone && the_clone != NULL) {
1548 igvn->remove_dead_node(the_clone);
1549 }
1550 phi->set_req(i, x);
1551 }
1552 // Record Phi
1553 igvn->register_new_node_with_optimizer(phi);
1554 return phi;
1555 }
1556
1557 //------------------------------Ideal------------------------------------------
1558 // If the load is from Field memory and the pointer is non-null, it might be possible to
1559 // zero out the control input.
1560 // If the offset is constant and the base is an object allocation,
1561 // try to hook me up to the exact initializing store.
1562 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1563 Node* p = MemNode::Ideal_common(phase, can_reshape);
1564 if (p) return (p == NodeSentinel) ? NULL : p;
1565
1566 Node* ctrl = in(MemNode::Control);
1567 Node* address = in(MemNode::Address);
1568 bool progress = false;
1569
1570 // Skip up past a SafePoint control. Cannot do this for Stores because
1571 // pointer stores & cardmarks must stay on the same side of a SafePoint.
1572 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint &&
1573 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw ) {
1574 ctrl = ctrl->in(0);
1575 set_req(MemNode::Control,ctrl);
1576 progress = true;
1577 }
1578
1579 intptr_t ignore = 0;
1580 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1581 if (base != NULL
1582 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
1583 // Check for useless control edge in some common special cases
1584 if (in(MemNode::Control) != NULL
1585 && can_remove_control()
1586 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1587 && all_controls_dominate(base, phase->C->start())) {
1588 // A method-invariant, non-null address (constant or 'this' argument).
1589 set_req(MemNode::Control, NULL);
1590 progress = true;
1591 }
1592 }
1593
1594 Node* mem = in(MemNode::Memory);
1595 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1596
1597 if (can_reshape && (addr_t != NULL)) {
1598 // try to optimize our memory input
1599 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase);
1600 if (opt_mem != mem) {
1601 set_req(MemNode::Memory, opt_mem);
1602 if (phase->type( opt_mem ) == Type::TOP) return NULL;
1603 return this;
1604 }
1605 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1606 if ((t_oop != NULL) &&
1607 (t_oop->is_known_instance_field() ||
1608 t_oop->is_ptr_to_boxed_value())) {
1609 PhaseIterGVN *igvn = phase->is_IterGVN();
1610 if (igvn != NULL && igvn->_worklist.member(opt_mem)) {
1611 // Delay this transformation until memory Phi is processed.
1612 phase->is_IterGVN()->_worklist.push(this);
1613 return NULL;
1614 }
1615 // Split instance field load through Phi.
1616 Node* result = split_through_phi(phase);
1617 if (result != NULL) return result;
1618
1619 if (t_oop->is_ptr_to_boxed_value()) {
1620 Node* result = eliminate_autobox(phase);
1621 if (result != NULL) return result;
1622 }
1623 }
1624 }
1625
1626 // Is there a dominating load that loads the same value? Leave
1627 // anything that is not a load of a field/array element (like
1628 // barriers etc.) alone
1629 if (in(0) != NULL && !adr_type()->isa_rawptr() && can_reshape) {
1630 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) {
1631 Node *use = mem->fast_out(i);
1632 if (use != this &&
1633 use->Opcode() == Opcode() &&
1634 use->in(0) != NULL &&
1635 use->in(0) != in(0) &&
1636 use->in(Address) == in(Address)) {
1637 Node* ctl = in(0);
1638 for (int i = 0; i < 10 && ctl != NULL; i++) {
1639 ctl = IfNode::up_one_dom(ctl);
1640 if (ctl == use->in(0)) {
1641 set_req(0, use->in(0));
1642 return this;
1643 }
1644 }
1645 }
1646 }
1647 }
1648
1649 // Check for prior store with a different base or offset; make Load
1650 // independent. Skip through any number of them. Bail out if the stores
1651 // are in an endless dead cycle and report no progress. This is a key
1652 // transform for Reflection. However, if after skipping through the Stores
1653 // we can't then fold up against a prior store do NOT do the transform as
1654 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
1655 // array memory alive twice: once for the hoisted Load and again after the
1656 // bypassed Store. This situation only works if EVERYBODY who does
1657 // anti-dependence work knows how to bypass. I.e. we need all
1658 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
1659 // the alias index stuff. So instead, peek through Stores and IFF we can
1660 // fold up, do so.
1661 Node* prev_mem = find_previous_store(phase);
1662 if (prev_mem != NULL) {
1663 Node* value = can_see_arraycopy_value(prev_mem, phase);
1664 if (value != NULL) {
1665 return value;
1666 }
1667 }
1668 // Steps (a), (b): Walk past independent stores to find an exact match.
1669 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) {
1670 // (c) See if we can fold up on the spot, but don't fold up here.
1671 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
1672 // just return a prior value, which is done by Identity calls.
1673 if (can_see_stored_value(prev_mem, phase)) {
1674 // Make ready for step (d):
1675 set_req(MemNode::Memory, prev_mem);
1676 return this;
1677 }
1678 }
1679
1680 AllocateNode* alloc = AllocateNode::Ideal_allocation(address, phase);
1681 if (alloc != NULL && mem->is_Proj() &&
1682 mem->in(0) != NULL &&
1683 mem->in(0) == alloc->initialization() &&
1684 Opcode() == Op_LoadX &&
1685 alloc->initialization()->proj_out_or_null(0) != NULL) {
1686 InitializeNode* init = alloc->initialization();
1687 Node* control = init->proj_out(0);
1688 return alloc->make_ideal_mark(phase, address, control, mem, NULL);
1689 }
1690
1691 return progress ? this : NULL;
1692 }
1693
1694 // Helper to recognize certain Klass fields which are invariant across
1695 // some group of array types (e.g., int[] or all T[] where T < Object).
1696 const Type*
1697 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1698 ciKlass* klass) const {
1699 if (tkls->offset() == in_bytes(Klass::modifier_flags_offset())) {
1700 // The field is Klass::_modifier_flags. Return its (constant) value.
1701 // (Folds up the 2nd indirection in aClassConstant.getModifiers().)
1702 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags");
1703 return TypeInt::make(klass->modifier_flags());
1704 }
1705 if (tkls->offset() == in_bytes(Klass::access_flags_offset())) {
1706 // The field is Klass::_access_flags. Return its (constant) value.
1707 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1708 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags");
1709 return TypeInt::make(klass->access_flags());
1710 }
1711 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) {
1712 // The field is Klass::_layout_helper. Return its constant value if known.
1713 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper");
1714 return TypeInt::make(klass->layout_helper());
1715 }
1716
1717 // No match.
1718 return NULL;
1719 }
1720
1721 //------------------------------Value-----------------------------------------
1722 const Type* LoadNode::Value(PhaseGVN* phase) const {
1723 // Either input is TOP ==> the result is TOP
1724 Node* mem = in(MemNode::Memory);
1725 const Type *t1 = phase->type(mem);
1726 if (t1 == Type::TOP) return Type::TOP;
1727 Node* adr = in(MemNode::Address);
1728 const TypePtr* tp = phase->type(adr)->isa_ptr();
1729 if (tp == NULL || tp->empty()) return Type::TOP;
1730 int off = tp->offset();
1731 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
1732 Compile* C = phase->C;
1733
1734 // Try to guess loaded type from pointer type
1735 if (tp->isa_aryptr()) {
1736 const TypeAryPtr* ary = tp->is_aryptr();
1737 const Type* t = ary->elem();
1738
1739 // Determine whether the reference is beyond the header or not, by comparing
1740 // the offset against the offset of the start of the array's data.
1741 // Different array types begin at slightly different offsets (12 vs. 16).
1742 // We choose T_BYTE as an example base type that is least restrictive
1743 // as to alignment, which will therefore produce the smallest
1744 // possible base offset.
1745 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
1746 const bool off_beyond_header = (off >= min_base_off);
1747
1748 // Try to constant-fold a stable array element.
1749 if (FoldStableValues && !is_mismatched_access() && ary->is_stable()) {
1750 // Make sure the reference is not into the header and the offset is constant
1751 ciObject* aobj = ary->const_oop();
1752 if (aobj != NULL && off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) {
1753 int stable_dimension = (ary->stable_dimension() > 0 ? ary->stable_dimension() - 1 : 0);
1754 const Type* con_type = Type::make_constant_from_array_element(aobj->as_array(), off,
1755 stable_dimension,
1756 memory_type(), is_unsigned());
1757 if (con_type != NULL) {
1758 return con_type;
1759 }
1760 }
1761 }
1762
1763 // Don't do this for integer types. There is only potential profit if
1764 // the element type t is lower than _type; that is, for int types, if _type is
1765 // more restrictive than t. This only happens here if one is short and the other
1766 // char (both 16 bits), and in those cases we've made an intentional decision
1767 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
1768 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
1769 //
1770 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
1771 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
1772 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
1773 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
1774 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
1775 // In fact, that could have been the original type of p1, and p1 could have
1776 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
1777 // expression (LShiftL quux 3) independently optimized to the constant 8.
1778 if ((t->isa_int() == NULL) && (t->isa_long() == NULL)
1779 && (_type->isa_vect() == NULL)
1780 && t->isa_valuetype() == NULL
1781 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
1782 // t might actually be lower than _type, if _type is a unique
1783 // concrete subclass of abstract class t.
1784 if (off_beyond_header || off == Type::OffsetBot) { // is the offset beyond the header?
1785 const Type* jt = t->join_speculative(_type);
1786 // In any case, do not allow the join, per se, to empty out the type.
1787 if (jt->empty() && !t->empty()) {
1788 // This can happen if a interface-typed array narrows to a class type.
1789 jt = _type;
1790 }
1791 #ifdef ASSERT
1792 if (phase->C->eliminate_boxing() && adr->is_AddP()) {
1793 // The pointers in the autobox arrays are always non-null
1794 Node* base = adr->in(AddPNode::Base);
1795 if ((base != NULL) && base->is_DecodeN()) {
1796 // Get LoadN node which loads IntegerCache.cache field
1797 base = base->in(1);
1798 }
1799 if ((base != NULL) && base->is_Con()) {
1800 const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr();
1801 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1802 // It could be narrow oop
1803 assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity");
1804 }
1805 }
1806 }
1807 #endif
1808 return jt;
1809 }
1810 }
1811 } else if (tp->base() == Type::InstPtr) {
1812 assert( off != Type::OffsetBot ||
1813 // arrays can be cast to Objects
1814 tp->is_oopptr()->klass()->is_java_lang_Object() ||
1815 tp->is_oopptr()->klass() == ciEnv::current()->Class_klass() ||
1816 // unsafe field access may not have a constant offset
1817 C->has_unsafe_access(),
1818 "Field accesses must be precise" );
1819 // For oop loads, we expect the _type to be precise.
1820
1821 // Optimize loads from constant fields.
1822 const TypeInstPtr* tinst = tp->is_instptr();
1823 ciObject* const_oop = tinst->const_oop();
1824 if (!is_mismatched_access() && off != Type::OffsetBot && const_oop != NULL && const_oop->is_instance()) {
1825 BasicType bt = memory_type();
1826 ciType* mirror_type = const_oop->as_instance()->java_mirror_type();
1827 if (mirror_type != NULL && mirror_type->is_valuetype()) {
1828 ciValueKlass* vk = mirror_type->as_value_klass();
1829 if (off == vk->default_value_offset()) {
1830 // Loading a special hidden field that contains the oop of the default value type
1831 const Type* const_oop = TypeInstPtr::make(vk->default_value_instance());
1832 return (bt == T_NARROWOOP) ? const_oop->make_narrowoop() : const_oop;
1833 }
1834 }
1835 const Type* con_type = Type::make_constant_from_field(const_oop->as_instance(), off, is_unsigned(), bt);
1836 if (con_type != NULL) {
1837 return con_type;
1838 }
1839 }
1840 } else if (tp->base() == Type::KlassPtr) {
1841 assert( off != Type::OffsetBot ||
1842 // arrays can be cast to Objects
1843 tp->is_klassptr()->klass() == NULL ||
1844 tp->is_klassptr()->klass()->is_java_lang_Object() ||
1845 // also allow array-loading from the primary supertype
1846 // array during subtype checks
1847 Opcode() == Op_LoadKlass,
1848 "Field accesses must be precise" );
1849 // For klass/static loads, we expect the _type to be precise
1850 } else if (tp->base() == Type::RawPtr && !StressReflectiveCode) {
1851 if (adr->is_Load() && off == 0) {
1852 /* With mirrors being an indirect in the Klass*
1853 * the VM is now using two loads. LoadKlass(LoadP(LoadP(Klass, mirror_offset), zero_offset))
1854 * The LoadP from the Klass has a RawPtr type (see LibraryCallKit::load_mirror_from_klass).
1855 *
1856 * So check the type and klass of the node before the LoadP.
1857 */
1858 Node* adr2 = adr->in(MemNode::Address);
1859 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
1860 if (tkls != NULL) {
1861 ciKlass* klass = tkls->klass();
1862 if (klass != NULL && klass->is_loaded() && tkls->klass_is_exact() && tkls->offset() == in_bytes(Klass::java_mirror_offset())) {
1863 assert(adr->Opcode() == Op_LoadP, "must load an oop from _java_mirror");
1864 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
1865 return TypeInstPtr::make(klass->java_mirror());
1866 }
1867 }
1868 } else {
1869 // Check for a load of the default value offset from the ValueKlassFixedBlock:
1870 // LoadI(LoadP(value_klass, adr_valueklass_fixed_block_offset), default_value_offset_offset)
1871 intptr_t offset = 0;
1872 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
1873 if (base != NULL && base->is_Load() && offset == in_bytes(ValueKlass::default_value_offset_offset())) {
1874 const TypeKlassPtr* tkls = phase->type(base->in(MemNode::Address))->isa_klassptr();
1875 if (tkls != NULL && tkls->is_loaded() && tkls->klass_is_exact() && tkls->isa_valuetype() &&
1876 tkls->offset() == in_bytes(InstanceKlass::adr_valueklass_fixed_block_offset())) {
1877 assert(base->Opcode() == Op_LoadP, "must load an oop from klass");
1878 assert(Opcode() == Op_LoadI, "must load an int from fixed block");
1879 return TypeInt::make(tkls->klass()->as_value_klass()->default_value_offset());
1880 }
1881 }
1882 }
1883 }
1884
1885 const TypeKlassPtr *tkls = tp->isa_klassptr();
1886 if (tkls != NULL && !StressReflectiveCode) {
1887 ciKlass* klass = tkls->klass();
1888 if (tkls->is_loaded() && tkls->klass_is_exact()) {
1889 // We are loading a field from a Klass metaobject whose identity
1890 // is known at compile time (the type is "exact" or "precise").
1891 // Check for fields we know are maintained as constants by the VM.
1892 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) {
1893 // The field is Klass::_super_check_offset. Return its (constant) value.
1894 // (Folds up type checking code.)
1895 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
1896 return TypeInt::make(klass->super_check_offset());
1897 }
1898 // Compute index into primary_supers array
1899 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1900 // Check for overflowing; use unsigned compare to handle the negative case.
1901 if( depth < ciKlass::primary_super_limit() ) {
1902 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1903 // (Folds up type checking code.)
1904 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1905 ciKlass *ss = klass->super_of_depth(depth);
1906 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1907 }
1908 const Type* aift = load_array_final_field(tkls, klass);
1909 if (aift != NULL) return aift;
1910 }
1911
1912 // We can still check if we are loading from the primary_supers array at a
1913 // shallow enough depth. Even though the klass is not exact, entries less
1914 // than or equal to its super depth are correct.
1915 if (tkls->is_loaded()) {
1916 ciType *inner = klass;
1917 while( inner->is_obj_array_klass() )
1918 inner = inner->as_obj_array_klass()->base_element_type();
1919 if( inner->is_instance_klass() &&
1920 !inner->as_instance_klass()->flags().is_interface() ) {
1921 // Compute index into primary_supers array
1922 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1923 // Check for overflowing; use unsigned compare to handle the negative case.
1924 if( depth < ciKlass::primary_super_limit() &&
1925 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case
1926 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1927 // (Folds up type checking code.)
1928 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1929 ciKlass *ss = klass->super_of_depth(depth);
1930 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1931 }
1932 }
1933 }
1934
1935 // If the type is enough to determine that the thing is not an array,
1936 // we can give the layout_helper a positive interval type.
1937 // This will help short-circuit some reflective code.
1938 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())
1939 && !klass->is_array_klass() // not directly typed as an array
1940 && !klass->is_interface() // specifically not Serializable & Cloneable
1941 && !klass->is_java_lang_Object() // not the supertype of all T[]
1942 ) {
1943 // Note: When interfaces are reliable, we can narrow the interface
1944 // test to (klass != Serializable && klass != Cloneable).
1945 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
1946 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
1947 // The key property of this type is that it folds up tests
1948 // for array-ness, since it proves that the layout_helper is positive.
1949 // Thus, a generic value like the basic object layout helper works fine.
1950 return TypeInt::make(min_size, max_jint, Type::WidenMin);
1951 }
1952 }
1953
1954 // If we are loading from a freshly-allocated object, produce a zero,
1955 // if the load is provably beyond the header of the object.
1956 // (Also allow a variable load from a fresh array to produce zero.)
1957 const TypeOopPtr *tinst = tp->isa_oopptr();
1958 bool is_instance = (tinst != NULL) && tinst->is_known_instance_field();
1959 bool is_boxed_value = (tinst != NULL) && tinst->is_ptr_to_boxed_value();
1960 if (ReduceFieldZeroing || is_instance || is_boxed_value) {
1961 Node* value = can_see_stored_value(mem,phase);
1962 if (value != NULL && value->is_Con()) {
1963 assert(value->bottom_type()->higher_equal(_type),"sanity");
1964 return value->bottom_type();
1965 }
1966 }
1967
1968 if (is_instance) {
1969 // If we have an instance type and our memory input is the
1970 // programs's initial memory state, there is no matching store,
1971 // so just return a zero of the appropriate type
1972 Node *mem = in(MemNode::Memory);
1973 if (mem->is_Parm() && mem->in(0)->is_Start()) {
1974 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
1975 return Type::get_zero_type(_type->basic_type());
1976 }
1977 }
1978 return _type;
1979 }
1980
1981 //------------------------------match_edge-------------------------------------
1982 // Do we Match on this edge index or not? Match only the address.
1983 uint LoadNode::match_edge(uint idx) const {
1984 return idx == MemNode::Address;
1985 }
1986
1987 //--------------------------LoadBNode::Ideal--------------------------------------
1988 //
1989 // If the previous store is to the same address as this load,
1990 // and the value stored was larger than a byte, replace this load
1991 // with the value stored truncated to a byte. If no truncation is
1992 // needed, the replacement is done in LoadNode::Identity().
1993 //
1994 Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1995 Node* mem = in(MemNode::Memory);
1996 Node* value = can_see_stored_value(mem,phase);
1997 if( value && !phase->type(value)->higher_equal( _type ) ) {
1998 Node *result = phase->transform( new LShiftINode(value, phase->intcon(24)) );
1999 return new RShiftINode(result, phase->intcon(24));
2000 }
2001 // Identity call will handle the case where truncation is not needed.
2002 return LoadNode::Ideal(phase, can_reshape);
2003 }
2004
2005 const Type* LoadBNode::Value(PhaseGVN* phase) const {
2006 Node* mem = in(MemNode::Memory);
2007 Node* value = can_see_stored_value(mem,phase);
2008 if (value != NULL && value->is_Con() &&
2009 !value->bottom_type()->higher_equal(_type)) {
2010 // If the input to the store does not fit with the load's result type,
2011 // it must be truncated. We can't delay until Ideal call since
2012 // a singleton Value is needed for split_thru_phi optimization.
2013 int con = value->get_int();
2014 return TypeInt::make((con << 24) >> 24);
2015 }
2016 return LoadNode::Value(phase);
2017 }
2018
2019 //--------------------------LoadUBNode::Ideal-------------------------------------
2020 //
2021 // If the previous store is to the same address as this load,
2022 // and the value stored was larger than a byte, replace this load
2023 // with the value stored truncated to a byte. If no truncation is
2024 // needed, the replacement is done in LoadNode::Identity().
2025 //
2026 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2027 Node* mem = in(MemNode::Memory);
2028 Node* value = can_see_stored_value(mem, phase);
2029 if (value && !phase->type(value)->higher_equal(_type))
2030 return new AndINode(value, phase->intcon(0xFF));
2031 // Identity call will handle the case where truncation is not needed.
2032 return LoadNode::Ideal(phase, can_reshape);
2033 }
2034
2035 const Type* LoadUBNode::Value(PhaseGVN* phase) const {
2036 Node* mem = in(MemNode::Memory);
2037 Node* value = can_see_stored_value(mem,phase);
2038 if (value != NULL && value->is_Con() &&
2039 !value->bottom_type()->higher_equal(_type)) {
2040 // If the input to the store does not fit with the load's result type,
2041 // it must be truncated. We can't delay until Ideal call since
2042 // a singleton Value is needed for split_thru_phi optimization.
2043 int con = value->get_int();
2044 return TypeInt::make(con & 0xFF);
2045 }
2046 return LoadNode::Value(phase);
2047 }
2048
2049 //--------------------------LoadUSNode::Ideal-------------------------------------
2050 //
2051 // If the previous store is to the same address as this load,
2052 // and the value stored was larger than a char, replace this load
2053 // with the value stored truncated to a char. If no truncation is
2054 // needed, the replacement is done in LoadNode::Identity().
2055 //
2056 Node *LoadUSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2057 Node* mem = in(MemNode::Memory);
2058 Node* value = can_see_stored_value(mem,phase);
2059 if( value && !phase->type(value)->higher_equal( _type ) )
2060 return new AndINode(value,phase->intcon(0xFFFF));
2061 // Identity call will handle the case where truncation is not needed.
2062 return LoadNode::Ideal(phase, can_reshape);
2063 }
2064
2065 const Type* LoadUSNode::Value(PhaseGVN* phase) const {
2066 Node* mem = in(MemNode::Memory);
2067 Node* value = can_see_stored_value(mem,phase);
2068 if (value != NULL && value->is_Con() &&
2069 !value->bottom_type()->higher_equal(_type)) {
2070 // If the input to the store does not fit with the load's result type,
2071 // it must be truncated. We can't delay until Ideal call since
2072 // a singleton Value is needed for split_thru_phi optimization.
2073 int con = value->get_int();
2074 return TypeInt::make(con & 0xFFFF);
2075 }
2076 return LoadNode::Value(phase);
2077 }
2078
2079 //--------------------------LoadSNode::Ideal--------------------------------------
2080 //
2081 // If the previous store is to the same address as this load,
2082 // and the value stored was larger than a short, replace this load
2083 // with the value stored truncated to a short. If no truncation is
2084 // needed, the replacement is done in LoadNode::Identity().
2085 //
2086 Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2087 Node* mem = in(MemNode::Memory);
2088 Node* value = can_see_stored_value(mem,phase);
2089 if( value && !phase->type(value)->higher_equal( _type ) ) {
2090 Node *result = phase->transform( new LShiftINode(value, phase->intcon(16)) );
2091 return new RShiftINode(result, phase->intcon(16));
2092 }
2093 // Identity call will handle the case where truncation is not needed.
2094 return LoadNode::Ideal(phase, can_reshape);
2095 }
2096
2097 const Type* LoadSNode::Value(PhaseGVN* phase) const {
2098 Node* mem = in(MemNode::Memory);
2099 Node* value = can_see_stored_value(mem,phase);
2100 if (value != NULL && value->is_Con() &&
2101 !value->bottom_type()->higher_equal(_type)) {
2102 // If the input to the store does not fit with the load's result type,
2103 // it must be truncated. We can't delay until Ideal call since
2104 // a singleton Value is needed for split_thru_phi optimization.
2105 int con = value->get_int();
2106 return TypeInt::make((con << 16) >> 16);
2107 }
2108 return LoadNode::Value(phase);
2109 }
2110
2111 //=============================================================================
2112 //----------------------------LoadKlassNode::make------------------------------
2113 // Polymorphic factory method:
2114 Node* LoadKlassNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* at, const TypeKlassPtr* tk) {
2115 // sanity check the alias category against the created node type
2116 const TypePtr *adr_type = adr->bottom_type()->isa_ptr();
2117 assert(adr_type != NULL, "expecting TypeKlassPtr");
2118 #ifdef _LP64
2119 if (adr_type->is_ptr_to_narrowklass()) {
2120 assert(UseCompressedClassPointers, "no compressed klasses");
2121 Node* load_klass = gvn.transform(new LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowklass(), MemNode::unordered));
2122 return new DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr());
2123 }
2124 #endif
2125 assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
2126 return new LoadKlassNode(ctl, mem, adr, at, tk, MemNode::unordered);
2127 }
2128
2129 //------------------------------Value------------------------------------------
2130 const Type* LoadKlassNode::Value(PhaseGVN* phase) const {
2131 return klass_value_common(phase);
2132 }
2133
2134 // In most cases, LoadKlassNode does not have the control input set. If the control
2135 // input is set, it must not be removed (by LoadNode::Ideal()).
2136 bool LoadKlassNode::can_remove_control() const {
2137 return false;
2138 }
2139
2140 const Type* LoadNode::klass_value_common(PhaseGVN* phase) const {
2141 // Either input is TOP ==> the result is TOP
2142 const Type *t1 = phase->type( in(MemNode::Memory) );
2143 if (t1 == Type::TOP) return Type::TOP;
2144 Node *adr = in(MemNode::Address);
2145 const Type *t2 = phase->type( adr );
2146 if (t2 == Type::TOP) return Type::TOP;
2147 const TypePtr *tp = t2->is_ptr();
2148 if (TypePtr::above_centerline(tp->ptr()) ||
2149 tp->ptr() == TypePtr::Null) return Type::TOP;
2150
2151 // Return a more precise klass, if possible
2152 const TypeInstPtr *tinst = tp->isa_instptr();
2153 if (tinst != NULL) {
2154 ciInstanceKlass* ik = tinst->klass()->as_instance_klass();
2155 int offset = tinst->offset();
2156 if (ik == phase->C->env()->Class_klass()
2157 && (offset == java_lang_Class::klass_offset_in_bytes() ||
2158 offset == java_lang_Class::array_klass_offset_in_bytes())) {
2159 // We are loading a special hidden field from a Class mirror object,
2160 // the field which points to the VM's Klass metaobject.
2161 ciType* t = tinst->java_mirror_type();
2162 // java_mirror_type returns non-null for compile-time Class constants.
2163 if (t != NULL) {
2164 // constant oop => constant klass
2165 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
2166 if (t->is_void()) {
2167 // We cannot create a void array. Since void is a primitive type return null
2168 // klass. Users of this result need to do a null check on the returned klass.
2169 return TypePtr::NULL_PTR;
2170 }
2171 return TypeKlassPtr::make(ciArrayKlass::make(t));
2172 }
2173 if (!t->is_klass()) {
2174 // a primitive Class (e.g., int.class) has NULL for a klass field
2175 return TypePtr::NULL_PTR;
2176 }
2177 // (Folds up the 1st indirection in aClassConstant.getModifiers().)
2178 return TypeKlassPtr::make(t->as_klass());
2179 }
2180 // non-constant mirror, so we can't tell what's going on
2181 }
2182 if( !ik->is_loaded() )
2183 return _type; // Bail out if not loaded
2184 if (offset == oopDesc::klass_offset_in_bytes()) {
2185 if (tinst->klass_is_exact()) {
2186 return TypeKlassPtr::make(ik);
2187 }
2188 // See if we can become precise: no subklasses and no interface
2189 // (Note: We need to support verified interfaces.)
2190 if (!ik->is_interface() && !ik->has_subklass()) {
2191 //assert(!UseExactTypes, "this code should be useless with exact types");
2192 // Add a dependence; if any subclass added we need to recompile
2193 if (!ik->is_final()) {
2194 // %%% should use stronger assert_unique_concrete_subtype instead
2195 phase->C->dependencies()->assert_leaf_type(ik);
2196 }
2197 // Return precise klass
2198 return TypeKlassPtr::make(ik);
2199 }
2200
2201 // Return root of possible klass
2202 return TypeKlassPtr::make(TypePtr::NotNull, ik, Type::Offset(0));
2203 }
2204 }
2205
2206 // Check for loading klass from an array
2207 const TypeAryPtr *tary = tp->isa_aryptr();
2208 if( tary != NULL ) {
2209 ciKlass *tary_klass = tary->klass();
2210 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP
2211 && tary->offset() == oopDesc::klass_offset_in_bytes()) {
2212 if (tary->klass_is_exact()) {
2213 return TypeKlassPtr::make(tary_klass);
2214 }
2215 ciArrayKlass *ak = tary->klass()->as_array_klass();
2216 // If the klass is an object array, we defer the question to the
2217 // array component klass.
2218 if( ak->is_obj_array_klass() ) {
2219 assert( ak->is_loaded(), "" );
2220 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass();
2221 if( base_k->is_loaded() && base_k->is_instance_klass() ) {
2222 ciInstanceKlass* ik = base_k->as_instance_klass();
2223 // See if we can become precise: no subklasses and no interface
2224 if (!ik->is_interface() && !ik->has_subklass()) {
2225 //assert(!UseExactTypes, "this code should be useless with exact types");
2226 // Add a dependence; if any subclass added we need to recompile
2227 if (!ik->is_final()) {
2228 phase->C->dependencies()->assert_leaf_type(ik);
2229 }
2230 // Return precise array klass
2231 return TypeKlassPtr::make(ak);
2232 }
2233 }
2234 return TypeKlassPtr::make(TypePtr::NotNull, ak, Type::Offset(0));
2235 } else { // Found a type-array?
2236 //assert(!UseExactTypes, "this code should be useless with exact types");
2237 assert( ak->is_type_array_klass(), "" );
2238 return TypeKlassPtr::make(ak); // These are always precise
2239 }
2240 }
2241 }
2242
2243 // Check for loading klass from an array klass
2244 const TypeKlassPtr *tkls = tp->isa_klassptr();
2245 if (tkls != NULL && !StressReflectiveCode) {
2246 if (!tkls->is_loaded()) {
2247 return _type; // Bail out if not loaded
2248 }
2249 ciKlass* klass = tkls->klass();
2250 if( klass->is_obj_array_klass() &&
2251 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) {
2252 ciKlass* elem = klass->as_obj_array_klass()->element_klass();
2253 // // Always returning precise element type is incorrect,
2254 // // e.g., element type could be object and array may contain strings
2255 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
2256
2257 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
2258 // according to the element type's subclassing.
2259 return TypeKlassPtr::make(tkls->ptr(), elem, Type::Offset(0));
2260 }
2261 if( klass->is_instance_klass() && tkls->klass_is_exact() &&
2262 tkls->offset() == in_bytes(Klass::super_offset())) {
2263 ciKlass* sup = klass->as_instance_klass()->super();
2264 // The field is Klass::_super. Return its (constant) value.
2265 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
2266 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR;
2267 }
2268 }
2269
2270 // Bailout case
2271 return LoadNode::Value(phase);
2272 }
2273
2274 //------------------------------Identity---------------------------------------
2275 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
2276 // Also feed through the klass in Allocate(...klass...)._klass.
2277 Node* LoadKlassNode::Identity(PhaseGVN* phase) {
2278 return klass_identity_common(phase);
2279 }
2280
2281 Node* LoadNode::klass_identity_common(PhaseGVN* phase) {
2282 Node* x = LoadNode::Identity(phase);
2283 if (x != this) return x;
2284
2285 // Take apart the address into an oop and and offset.
2286 // Return 'this' if we cannot.
2287 Node* adr = in(MemNode::Address);
2288 intptr_t offset = 0;
2289 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2290 if (base == NULL) return this;
2291 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
2292 if (toop == NULL) return this;
2293
2294 // Step over potential GC barrier for OopHandle resolve
2295 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
2296 if (bs->is_gc_barrier_node(base)) {
2297 base = bs->step_over_gc_barrier(base);
2298 }
2299
2300 // We can fetch the klass directly through an AllocateNode.
2301 // This works even if the klass is not constant (clone or newArray).
2302 if (offset == oopDesc::klass_offset_in_bytes()) {
2303 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
2304 if (allocated_klass != NULL) {
2305 return allocated_klass;
2306 }
2307 }
2308
2309 // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*.
2310 // See inline_native_Class_query for occurrences of these patterns.
2311 // Java Example: x.getClass().isAssignableFrom(y)
2312 //
2313 // This improves reflective code, often making the Class
2314 // mirror go completely dead. (Current exception: Class
2315 // mirrors may appear in debug info, but we could clean them out by
2316 // introducing a new debug info operator for Klass.java_mirror).
2317
2318 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass()
2319 && offset == java_lang_Class::klass_offset_in_bytes()) {
2320 if (base->is_Load()) {
2321 Node* base2 = base->in(MemNode::Address);
2322 if (base2->is_Load()) { /* direct load of a load which is the OopHandle */
2323 Node* adr2 = base2->in(MemNode::Address);
2324 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2325 if (tkls != NULL && !tkls->empty()
2326 && (tkls->klass()->is_instance_klass() ||
2327 tkls->klass()->is_array_klass())
2328 && adr2->is_AddP()
2329 ) {
2330 int mirror_field = in_bytes(Klass::java_mirror_offset());
2331 if (tkls->offset() == mirror_field) {
2332 return adr2->in(AddPNode::Base);
2333 }
2334 }
2335 }
2336 }
2337 }
2338
2339 return this;
2340 }
2341
2342
2343 //------------------------------Value------------------------------------------
2344 const Type* LoadNKlassNode::Value(PhaseGVN* phase) const {
2345 const Type *t = klass_value_common(phase);
2346 if (t == Type::TOP)
2347 return t;
2348
2349 return t->make_narrowklass();
2350 }
2351
2352 //------------------------------Identity---------------------------------------
2353 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
2354 // Also feed through the klass in Allocate(...klass...)._klass.
2355 Node* LoadNKlassNode::Identity(PhaseGVN* phase) {
2356 Node *x = klass_identity_common(phase);
2357
2358 const Type *t = phase->type( x );
2359 if( t == Type::TOP ) return x;
2360 if( t->isa_narrowklass()) return x;
2361 assert (!t->isa_narrowoop(), "no narrow oop here");
2362
2363 return phase->transform(new EncodePKlassNode(x, t->make_narrowklass()));
2364 }
2365
2366 //------------------------------Value-----------------------------------------
2367 const Type* LoadRangeNode::Value(PhaseGVN* phase) const {
2368 // Either input is TOP ==> the result is TOP
2369 const Type *t1 = phase->type( in(MemNode::Memory) );
2370 if( t1 == Type::TOP ) return Type::TOP;
2371 Node *adr = in(MemNode::Address);
2372 const Type *t2 = phase->type( adr );
2373 if( t2 == Type::TOP ) return Type::TOP;
2374 const TypePtr *tp = t2->is_ptr();
2375 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
2376 const TypeAryPtr *tap = tp->isa_aryptr();
2377 if( !tap ) return _type;
2378 return tap->size();
2379 }
2380
2381 //-------------------------------Ideal---------------------------------------
2382 // Feed through the length in AllocateArray(...length...)._length.
2383 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2384 Node* p = MemNode::Ideal_common(phase, can_reshape);
2385 if (p) return (p == NodeSentinel) ? NULL : p;
2386
2387 // Take apart the address into an oop and and offset.
2388 // Return 'this' if we cannot.
2389 Node* adr = in(MemNode::Address);
2390 intptr_t offset = 0;
2391 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2392 if (base == NULL) return NULL;
2393 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2394 if (tary == NULL) return NULL;
2395
2396 // We can fetch the length directly through an AllocateArrayNode.
2397 // This works even if the length is not constant (clone or newArray).
2398 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2399 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2400 if (alloc != NULL) {
2401 Node* allocated_length = alloc->Ideal_length();
2402 Node* len = alloc->make_ideal_length(tary, phase);
2403 if (allocated_length != len) {
2404 // New CastII improves on this.
2405 return len;
2406 }
2407 }
2408 }
2409
2410 return NULL;
2411 }
2412
2413 //------------------------------Identity---------------------------------------
2414 // Feed through the length in AllocateArray(...length...)._length.
2415 Node* LoadRangeNode::Identity(PhaseGVN* phase) {
2416 Node* x = LoadINode::Identity(phase);
2417 if (x != this) return x;
2418
2419 // Take apart the address into an oop and and offset.
2420 // Return 'this' if we cannot.
2421 Node* adr = in(MemNode::Address);
2422 intptr_t offset = 0;
2423 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2424 if (base == NULL) return this;
2425 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2426 if (tary == NULL) return this;
2427
2428 // We can fetch the length directly through an AllocateArrayNode.
2429 // This works even if the length is not constant (clone or newArray).
2430 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2431 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2432 if (alloc != NULL) {
2433 Node* allocated_length = alloc->Ideal_length();
2434 // Do not allow make_ideal_length to allocate a CastII node.
2435 Node* len = alloc->make_ideal_length(tary, phase, false);
2436 if (allocated_length == len) {
2437 // Return allocated_length only if it would not be improved by a CastII.
2438 return allocated_length;
2439 }
2440 }
2441 }
2442
2443 return this;
2444
2445 }
2446
2447 //=============================================================================
2448 //---------------------------StoreNode::make-----------------------------------
2449 // Polymorphic factory method:
2450 StoreNode* StoreNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt, MemOrd mo) {
2451 assert((mo == unordered || mo == release), "unexpected");
2452 Compile* C = gvn.C;
2453 assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2454 ctl != NULL, "raw memory operations should have control edge");
2455
2456 switch (bt) {
2457 case T_BOOLEAN: val = gvn.transform(new AndINode(val, gvn.intcon(0x1))); // Fall through to T_BYTE case
2458 case T_BYTE: return new StoreBNode(ctl, mem, adr, adr_type, val, mo);
2459 case T_INT: return new StoreINode(ctl, mem, adr, adr_type, val, mo);
2460 case T_CHAR:
2461 case T_SHORT: return new StoreCNode(ctl, mem, adr, adr_type, val, mo);
2462 case T_LONG: return new StoreLNode(ctl, mem, adr, adr_type, val, mo);
2463 case T_FLOAT: return new StoreFNode(ctl, mem, adr, adr_type, val, mo);
2464 case T_DOUBLE: return new StoreDNode(ctl, mem, adr, adr_type, val, mo);
2465 case T_METADATA:
2466 case T_ADDRESS:
2467 case T_VALUETYPE:
2468 case T_OBJECT:
2469 #ifdef _LP64
2470 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
2471 val = gvn.transform(new EncodePNode(val, val->bottom_type()->make_narrowoop()));
2472 return new StoreNNode(ctl, mem, adr, adr_type, val, mo);
2473 } else if (adr->bottom_type()->is_ptr_to_narrowklass() ||
2474 (UseCompressedClassPointers && val->bottom_type()->isa_klassptr() &&
2475 adr->bottom_type()->isa_rawptr())) {
2476 val = gvn.transform(new EncodePKlassNode(val, val->bottom_type()->make_narrowklass()));
2477 return new StoreNKlassNode(ctl, mem, adr, adr_type, val, mo);
2478 }
2479 #endif
2480 {
2481 return new StorePNode(ctl, mem, adr, adr_type, val, mo);
2482 }
2483 default:
2484 ShouldNotReachHere();
2485 return (StoreNode*)NULL;
2486 }
2487 }
2488
2489 StoreLNode* StoreLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
2490 bool require_atomic = true;
2491 return new StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
2492 }
2493
2494 StoreDNode* StoreDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
2495 bool require_atomic = true;
2496 return new StoreDNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
2497 }
2498
2499
2500 //--------------------------bottom_type----------------------------------------
2501 const Type *StoreNode::bottom_type() const {
2502 return Type::MEMORY;
2503 }
2504
2505 //------------------------------hash-------------------------------------------
2506 uint StoreNode::hash() const {
2507 // unroll addition of interesting fields
2508 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2509
2510 // Since they are not commoned, do not hash them:
2511 return NO_HASH;
2512 }
2513
2514 //------------------------------Ideal------------------------------------------
2515 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
2516 // When a store immediately follows a relevant allocation/initialization,
2517 // try to capture it into the initialization, or hoist it above.
2518 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2519 Node* p = MemNode::Ideal_common(phase, can_reshape);
2520 if (p) return (p == NodeSentinel) ? NULL : p;
2521
2522 Node* mem = in(MemNode::Memory);
2523 Node* address = in(MemNode::Address);
2524 // Back-to-back stores to same address? Fold em up. Generally
2525 // unsafe if I have intervening uses... Also disallowed for StoreCM
2526 // since they must follow each StoreP operation. Redundant StoreCMs
2527 // are eliminated just before matching in final_graph_reshape.
2528 {
2529 Node* st = mem;
2530 // If Store 'st' has more than one use, we cannot fold 'st' away.
2531 // For example, 'st' might be the final state at a conditional
2532 // return. Or, 'st' might be used by some node which is live at
2533 // the same time 'st' is live, which might be unschedulable. So,
2534 // require exactly ONE user until such time as we clone 'mem' for
2535 // each of 'mem's uses (thus making the exactly-1-user-rule hold
2536 // true).
2537 while (st->is_Store() && st->outcnt() == 1 && st->Opcode() != Op_StoreCM) {
2538 // Looking at a dead closed cycle of memory?
2539 assert(st != st->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
2540 assert(Opcode() == st->Opcode() ||
2541 st->Opcode() == Op_StoreVector ||
2542 Opcode() == Op_StoreVector ||
2543 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw ||
2544 (Opcode() == Op_StoreL && st->Opcode() == Op_StoreI) || // expanded ClearArrayNode
2545 (Opcode() == Op_StoreI && st->Opcode() == Op_StoreL) || // initialization by arraycopy
2546 (Opcode() == Op_StoreL && st->Opcode() == Op_StoreN) ||
2547 (is_mismatched_access() || st->as_Store()->is_mismatched_access()),
2548 "no mismatched stores, except on raw memory: %s %s", NodeClassNames[Opcode()], NodeClassNames[st->Opcode()]);
2549
2550 if (st->in(MemNode::Address)->eqv_uncast(address) &&
2551 st->as_Store()->memory_size() <= this->memory_size()) {
2552 Node* use = st->raw_out(0);
2553 phase->igvn_rehash_node_delayed(use);
2554 if (can_reshape) {
2555 use->set_req_X(MemNode::Memory, st->in(MemNode::Memory), phase->is_IterGVN());
2556 } else {
2557 // It's OK to do this in the parser, since DU info is always accurate,
2558 // and the parser always refers to nodes via SafePointNode maps.
2559 use->set_req(MemNode::Memory, st->in(MemNode::Memory));
2560 }
2561 return this;
2562 }
2563 st = st->in(MemNode::Memory);
2564 }
2565 }
2566
2567
2568 // Capture an unaliased, unconditional, simple store into an initializer.
2569 // Or, if it is independent of the allocation, hoist it above the allocation.
2570 if (ReduceFieldZeroing && /*can_reshape &&*/
2571 mem->is_Proj() && mem->in(0)->is_Initialize()) {
2572 InitializeNode* init = mem->in(0)->as_Initialize();
2573 intptr_t offset = init->can_capture_store(this, phase, can_reshape);
2574 if (offset > 0) {
2575 Node* moved = init->capture_store(this, offset, phase, can_reshape);
2576 // If the InitializeNode captured me, it made a raw copy of me,
2577 // and I need to disappear.
2578 if (moved != NULL) {
2579 // %%% hack to ensure that Ideal returns a new node:
2580 mem = MergeMemNode::make(mem);
2581 return mem; // fold me away
2582 }
2583 }
2584 }
2585
2586 return NULL; // No further progress
2587 }
2588
2589 //------------------------------Value-----------------------------------------
2590 const Type* StoreNode::Value(PhaseGVN* phase) const {
2591 // Either input is TOP ==> the result is TOP
2592 const Type *t1 = phase->type( in(MemNode::Memory) );
2593 if( t1 == Type::TOP ) return Type::TOP;
2594 const Type *t2 = phase->type( in(MemNode::Address) );
2595 if( t2 == Type::TOP ) return Type::TOP;
2596 const Type *t3 = phase->type( in(MemNode::ValueIn) );
2597 if( t3 == Type::TOP ) return Type::TOP;
2598 return Type::MEMORY;
2599 }
2600
2601 //------------------------------Identity---------------------------------------
2602 // Remove redundant stores:
2603 // Store(m, p, Load(m, p)) changes to m.
2604 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
2605 Node* StoreNode::Identity(PhaseGVN* phase) {
2606 Node* mem = in(MemNode::Memory);
2607 Node* adr = in(MemNode::Address);
2608 Node* val = in(MemNode::ValueIn);
2609
2610 Node* result = this;
2611
2612 // Load then Store? Then the Store is useless
2613 if (val->is_Load() &&
2614 val->in(MemNode::Address)->eqv_uncast(adr) &&
2615 val->in(MemNode::Memory )->eqv_uncast(mem) &&
2616 val->as_Load()->store_Opcode() == Opcode()) {
2617 result = mem;
2618 }
2619
2620 // Two stores in a row of the same value?
2621 if (result == this &&
2622 mem->is_Store() &&
2623 mem->in(MemNode::Address)->eqv_uncast(adr) &&
2624 mem->in(MemNode::ValueIn)->eqv_uncast(val) &&
2625 mem->Opcode() == Opcode()) {
2626 result = mem;
2627 }
2628
2629 // Store of zero anywhere into a freshly-allocated object?
2630 // Then the store is useless.
2631 // (It must already have been captured by the InitializeNode.)
2632 if (result == this && ReduceFieldZeroing) {
2633 // a newly allocated object is already all-zeroes everywhere
2634 if (mem->is_Proj() && mem->in(0)->is_Allocate() &&
2635 (phase->type(val)->is_zero_type() || mem->in(0)->in(AllocateNode::DefaultValue) == val)) {
2636 assert(!phase->type(val)->is_zero_type() || mem->in(0)->in(AllocateNode::DefaultValue) == NULL, "storing null to value array is forbidden");
2637 result = mem;
2638 }
2639
2640 if (result == this) {
2641 // the store may also apply to zero-bits in an earlier object
2642 Node* prev_mem = find_previous_store(phase);
2643 // Steps (a), (b): Walk past independent stores to find an exact match.
2644 if (prev_mem != NULL) {
2645 Node* prev_val = can_see_stored_value(prev_mem, phase);
2646 if (prev_val != NULL && phase->eqv(prev_val, val)) {
2647 // prev_val and val might differ by a cast; it would be good
2648 // to keep the more informative of the two.
2649 if (phase->type(val)->is_zero_type()) {
2650 result = mem;
2651 } else if (prev_mem->is_Proj() && prev_mem->in(0)->is_Initialize()) {
2652 InitializeNode* init = prev_mem->in(0)->as_Initialize();
2653 AllocateNode* alloc = init->allocation();
2654 if (alloc != NULL && alloc->in(AllocateNode::DefaultValue) == val) {
2655 result = mem;
2656 }
2657 }
2658 }
2659 }
2660 }
2661 }
2662
2663 if (result != this && phase->is_IterGVN() != NULL) {
2664 MemBarNode* trailing = trailing_membar();
2665 if (trailing != NULL) {
2666 #ifdef ASSERT
2667 const TypeOopPtr* t_oop = phase->type(in(Address))->isa_oopptr();
2668 assert(t_oop == NULL || t_oop->is_known_instance_field(), "only for non escaping objects");
2669 #endif
2670 PhaseIterGVN* igvn = phase->is_IterGVN();
2671 trailing->remove(igvn);
2672 }
2673 }
2674
2675 return result;
2676 }
2677
2678 //------------------------------match_edge-------------------------------------
2679 // Do we Match on this edge index or not? Match only memory & value
2680 uint StoreNode::match_edge(uint idx) const {
2681 return idx == MemNode::Address || idx == MemNode::ValueIn;
2682 }
2683
2684 //------------------------------cmp--------------------------------------------
2685 // Do not common stores up together. They generally have to be split
2686 // back up anyways, so do not bother.
2687 uint StoreNode::cmp( const Node &n ) const {
2688 return (&n == this); // Always fail except on self
2689 }
2690
2691 //------------------------------Ideal_masked_input-----------------------------
2692 // Check for a useless mask before a partial-word store
2693 // (StoreB ... (AndI valIn conIa) )
2694 // If (conIa & mask == mask) this simplifies to
2695 // (StoreB ... (valIn) )
2696 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
2697 Node *val = in(MemNode::ValueIn);
2698 if( val->Opcode() == Op_AndI ) {
2699 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2700 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
2701 set_req(MemNode::ValueIn, val->in(1));
2702 return this;
2703 }
2704 }
2705 return NULL;
2706 }
2707
2708
2709 //------------------------------Ideal_sign_extended_input----------------------
2710 // Check for useless sign-extension before a partial-word store
2711 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) )
2712 // If (conIL == conIR && conIR <= num_bits) this simplifies to
2713 // (StoreB ... (valIn) )
2714 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) {
2715 Node *val = in(MemNode::ValueIn);
2716 if( val->Opcode() == Op_RShiftI ) {
2717 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2718 if( t && t->is_con() && (t->get_con() <= num_bits) ) {
2719 Node *shl = val->in(1);
2720 if( shl->Opcode() == Op_LShiftI ) {
2721 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int();
2722 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) {
2723 set_req(MemNode::ValueIn, shl->in(1));
2724 return this;
2725 }
2726 }
2727 }
2728 }
2729 return NULL;
2730 }
2731
2732 //------------------------------value_never_loaded-----------------------------------
2733 // Determine whether there are any possible loads of the value stored.
2734 // For simplicity, we actually check if there are any loads from the
2735 // address stored to, not just for loads of the value stored by this node.
2736 //
2737 bool StoreNode::value_never_loaded( PhaseTransform *phase) const {
2738 Node *adr = in(Address);
2739 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
2740 if (adr_oop == NULL)
2741 return false;
2742 if (!adr_oop->is_known_instance_field())
2743 return false; // if not a distinct instance, there may be aliases of the address
2744 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
2745 Node *use = adr->fast_out(i);
2746 if (use->is_Load() || use->is_LoadStore()) {
2747 return false;
2748 }
2749 }
2750 return true;
2751 }
2752
2753 MemBarNode* StoreNode::trailing_membar() const {
2754 if (is_release()) {
2755 MemBarNode* trailing_mb = NULL;
2756 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
2757 Node* u = fast_out(i);
2758 if (u->is_MemBar()) {
2759 if (u->as_MemBar()->trailing_store()) {
2760 assert(u->Opcode() == Op_MemBarVolatile, "");
2761 assert(trailing_mb == NULL, "only one");
2762 trailing_mb = u->as_MemBar();
2763 #ifdef ASSERT
2764 Node* leading = u->as_MemBar()->leading_membar();
2765 assert(leading->Opcode() == Op_MemBarRelease, "incorrect membar");
2766 assert(leading->as_MemBar()->leading_store(), "incorrect membar pair");
2767 assert(leading->as_MemBar()->trailing_membar() == u, "incorrect membar pair");
2768 #endif
2769 } else {
2770 assert(u->as_MemBar()->standalone(), "");
2771 }
2772 }
2773 }
2774 return trailing_mb;
2775 }
2776 return NULL;
2777 }
2778
2779
2780 //=============================================================================
2781 //------------------------------Ideal------------------------------------------
2782 // If the store is from an AND mask that leaves the low bits untouched, then
2783 // we can skip the AND operation. If the store is from a sign-extension
2784 // (a left shift, then right shift) we can skip both.
2785 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
2786 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
2787 if( progress != NULL ) return progress;
2788
2789 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
2790 if( progress != NULL ) return progress;
2791
2792 // Finally check the default case
2793 return StoreNode::Ideal(phase, can_reshape);
2794 }
2795
2796 //=============================================================================
2797 //------------------------------Ideal------------------------------------------
2798 // If the store is from an AND mask that leaves the low bits untouched, then
2799 // we can skip the AND operation
2800 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
2801 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
2802 if( progress != NULL ) return progress;
2803
2804 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
2805 if( progress != NULL ) return progress;
2806
2807 // Finally check the default case
2808 return StoreNode::Ideal(phase, can_reshape);
2809 }
2810
2811 //=============================================================================
2812 //------------------------------Identity---------------------------------------
2813 Node* StoreCMNode::Identity(PhaseGVN* phase) {
2814 // No need to card mark when storing a null ptr
2815 Node* my_store = in(MemNode::OopStore);
2816 if (my_store->is_Store()) {
2817 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) );
2818 if( t1 == TypePtr::NULL_PTR ) {
2819 return in(MemNode::Memory);
2820 }
2821 }
2822 return this;
2823 }
2824
2825 //=============================================================================
2826 //------------------------------Ideal---------------------------------------
2827 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){
2828 Node* progress = StoreNode::Ideal(phase, can_reshape);
2829 if (progress != NULL) return progress;
2830
2831 Node* my_store = in(MemNode::OopStore);
2832 if (my_store->is_MergeMem()) {
2833 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx());
2834 set_req(MemNode::OopStore, mem);
2835 return this;
2836 }
2837
2838 return NULL;
2839 }
2840
2841 //------------------------------Value-----------------------------------------
2842 const Type* StoreCMNode::Value(PhaseGVN* phase) const {
2843 // Either input is TOP ==> the result is TOP
2844 const Type *t = phase->type( in(MemNode::Memory) );
2845 if( t == Type::TOP ) return Type::TOP;
2846 t = phase->type( in(MemNode::Address) );
2847 if( t == Type::TOP ) return Type::TOP;
2848 t = phase->type( in(MemNode::ValueIn) );
2849 if( t == Type::TOP ) return Type::TOP;
2850 // If extra input is TOP ==> the result is TOP
2851 t = phase->type( in(MemNode::OopStore) );
2852 if( t == Type::TOP ) return Type::TOP;
2853
2854 return StoreNode::Value( phase );
2855 }
2856
2857
2858 //=============================================================================
2859 //----------------------------------SCMemProjNode------------------------------
2860 const Type* SCMemProjNode::Value(PhaseGVN* phase) const
2861 {
2862 return bottom_type();
2863 }
2864
2865 //=============================================================================
2866 //----------------------------------LoadStoreNode------------------------------
2867 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required )
2868 : Node(required),
2869 _type(rt),
2870 _adr_type(at)
2871 {
2872 init_req(MemNode::Control, c );
2873 init_req(MemNode::Memory , mem);
2874 init_req(MemNode::Address, adr);
2875 init_req(MemNode::ValueIn, val);
2876 init_class_id(Class_LoadStore);
2877 }
2878
2879 uint LoadStoreNode::ideal_reg() const {
2880 return _type->ideal_reg();
2881 }
2882
2883 bool LoadStoreNode::result_not_used() const {
2884 for( DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++ ) {
2885 Node *x = fast_out(i);
2886 if (x->Opcode() == Op_SCMemProj) continue;
2887 return false;
2888 }
2889 return true;
2890 }
2891
2892 MemBarNode* LoadStoreNode::trailing_membar() const {
2893 MemBarNode* trailing = NULL;
2894 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
2895 Node* u = fast_out(i);
2896 if (u->is_MemBar()) {
2897 if (u->as_MemBar()->trailing_load_store()) {
2898 assert(u->Opcode() == Op_MemBarAcquire, "");
2899 assert(trailing == NULL, "only one");
2900 trailing = u->as_MemBar();
2901 #ifdef ASSERT
2902 Node* leading = trailing->leading_membar();
2903 assert(support_IRIW_for_not_multiple_copy_atomic_cpu || leading->Opcode() == Op_MemBarRelease, "incorrect membar");
2904 assert(leading->as_MemBar()->leading_load_store(), "incorrect membar pair");
2905 assert(leading->as_MemBar()->trailing_membar() == trailing, "incorrect membar pair");
2906 #endif
2907 } else {
2908 assert(u->as_MemBar()->standalone(), "wrong barrier kind");
2909 }
2910 }
2911 }
2912
2913 return trailing;
2914 }
2915
2916 uint LoadStoreNode::size_of() const { return sizeof(*this); }
2917
2918 //=============================================================================
2919 //----------------------------------LoadStoreConditionalNode--------------------
2920 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, NULL, TypeInt::BOOL, 5) {
2921 init_req(ExpectedIn, ex );
2922 }
2923
2924 //=============================================================================
2925 //-------------------------------adr_type--------------------------------------
2926 const TypePtr* ClearArrayNode::adr_type() const {
2927 Node *adr = in(3);
2928 if (adr == NULL) return NULL; // node is dead
2929 return MemNode::calculate_adr_type(adr->bottom_type());
2930 }
2931
2932 //------------------------------match_edge-------------------------------------
2933 // Do we Match on this edge index or not? Do not match memory
2934 uint ClearArrayNode::match_edge(uint idx) const {
2935 return idx > 1;
2936 }
2937
2938 //------------------------------Identity---------------------------------------
2939 // Clearing a zero length array does nothing
2940 Node* ClearArrayNode::Identity(PhaseGVN* phase) {
2941 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
2942 }
2943
2944 //------------------------------Idealize---------------------------------------
2945 // Clearing a short array is faster with stores
2946 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2947 // Already know this is a large node, do not try to ideal it
2948 if (!IdealizeClearArrayNode || _is_large) return NULL;
2949
2950 const int unit = BytesPerLong;
2951 const TypeX* t = phase->type(in(2))->isa_intptr_t();
2952 if (!t) return NULL;
2953 if (!t->is_con()) return NULL;
2954 intptr_t raw_count = t->get_con();
2955 intptr_t size = raw_count;
2956 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
2957 // Clearing nothing uses the Identity call.
2958 // Negative clears are possible on dead ClearArrays
2959 // (see jck test stmt114.stmt11402.val).
2960 if (size <= 0 || size % unit != 0) return NULL;
2961 intptr_t count = size / unit;
2962 // Length too long; communicate this to matchers and assemblers.
2963 // Assemblers are responsible to produce fast hardware clears for it.
2964 if (size > InitArrayShortSize) {
2965 return new ClearArrayNode(in(0), in(1), in(2), in(3), in(4), true);
2966 }
2967 Node *mem = in(1);
2968 if( phase->type(mem)==Type::TOP ) return NULL;
2969 Node *adr = in(3);
2970 const Type* at = phase->type(adr);
2971 if( at==Type::TOP ) return NULL;
2972 const TypePtr* atp = at->isa_ptr();
2973 // adjust atp to be the correct array element address type
2974 if (atp == NULL) atp = TypePtr::BOTTOM;
2975 else atp = atp->add_offset(Type::OffsetBot);
2976 // Get base for derived pointer purposes
2977 if( adr->Opcode() != Op_AddP ) Unimplemented();
2978 Node *base = adr->in(1);
2979
2980 Node *val = in(4);
2981 Node *off = phase->MakeConX(BytesPerLong);
2982 mem = new StoreLNode(in(0), mem, adr, atp, val, MemNode::unordered, false);
2983 count--;
2984 while( count-- ) {
2985 mem = phase->transform(mem);
2986 adr = phase->transform(new AddPNode(base,adr,off));
2987 mem = new StoreLNode(in(0), mem, adr, atp, val, MemNode::unordered, false);
2988 }
2989 return mem;
2990 }
2991
2992 //----------------------------step_through----------------------------------
2993 // Return allocation input memory edge if it is different instance
2994 // or itself if it is the one we are looking for.
2995 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) {
2996 Node* n = *np;
2997 assert(n->is_ClearArray(), "sanity");
2998 intptr_t offset;
2999 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
3000 // This method is called only before Allocate nodes are expanded
3001 // during macro nodes expansion. Before that ClearArray nodes are
3002 // only generated in PhaseMacroExpand::generate_arraycopy() (before
3003 // Allocate nodes are expanded) which follows allocations.
3004 assert(alloc != NULL, "should have allocation");
3005 if (alloc->_idx == instance_id) {
3006 // Can not bypass initialization of the instance we are looking for.
3007 return false;
3008 }
3009 // Otherwise skip it.
3010 InitializeNode* init = alloc->initialization();
3011 if (init != NULL)
3012 *np = init->in(TypeFunc::Memory);
3013 else
3014 *np = alloc->in(TypeFunc::Memory);
3015 return true;
3016 }
3017
3018 //----------------------------clear_memory-------------------------------------
3019 // Generate code to initialize object storage to zero.
3020 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
3021 Node* val,
3022 Node* raw_val,
3023 intptr_t start_offset,
3024 Node* end_offset,
3025 PhaseGVN* phase) {
3026 intptr_t offset = start_offset;
3027
3028 int unit = BytesPerLong;
3029 if ((offset % unit) != 0) {
3030 Node* adr = new AddPNode(dest, dest, phase->MakeConX(offset));
3031 adr = phase->transform(adr);
3032 const TypePtr* atp = TypeRawPtr::BOTTOM;
3033 if (val != NULL) {
3034 assert(phase->type(val)->isa_narrowoop(), "should be narrow oop");
3035 mem = new StoreNNode(ctl, mem, adr, atp, val, MemNode::unordered);
3036 } else {
3037 assert(raw_val == NULL, "val may not be null");
3038 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
3039 }
3040 mem = phase->transform(mem);
3041 offset += BytesPerInt;
3042 }
3043 assert((offset % unit) == 0, "");
3044
3045 // Initialize the remaining stuff, if any, with a ClearArray.
3046 return clear_memory(ctl, mem, dest, raw_val, phase->MakeConX(offset), end_offset, phase);
3047 }
3048
3049 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
3050 Node* raw_val,
3051 Node* start_offset,
3052 Node* end_offset,
3053 PhaseGVN* phase) {
3054 if (start_offset == end_offset) {
3055 // nothing to do
3056 return mem;
3057 }
3058
3059 int unit = BytesPerLong;
3060 Node* zbase = start_offset;
3061 Node* zend = end_offset;
3062
3063 // Scale to the unit required by the CPU:
3064 if (!Matcher::init_array_count_is_in_bytes) {
3065 Node* shift = phase->intcon(exact_log2(unit));
3066 zbase = phase->transform(new URShiftXNode(zbase, shift) );
3067 zend = phase->transform(new URShiftXNode(zend, shift) );
3068 }
3069
3070 // Bulk clear double-words
3071 Node* zsize = phase->transform(new SubXNode(zend, zbase) );
3072 Node* adr = phase->transform(new AddPNode(dest, dest, start_offset) );
3073 if (raw_val == NULL) {
3074 raw_val = phase->MakeConX(0);
3075 }
3076 mem = new ClearArrayNode(ctl, mem, zsize, adr, raw_val, false);
3077 return phase->transform(mem);
3078 }
3079
3080 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
3081 Node* val,
3082 Node* raw_val,
3083 intptr_t start_offset,
3084 intptr_t end_offset,
3085 PhaseGVN* phase) {
3086 if (start_offset == end_offset) {
3087 // nothing to do
3088 return mem;
3089 }
3090
3091 assert((end_offset % BytesPerInt) == 0, "odd end offset");
3092 intptr_t done_offset = end_offset;
3093 if ((done_offset % BytesPerLong) != 0) {
3094 done_offset -= BytesPerInt;
3095 }
3096 if (done_offset > start_offset) {
3097 mem = clear_memory(ctl, mem, dest, val, raw_val,
3098 start_offset, phase->MakeConX(done_offset), phase);
3099 }
3100 if (done_offset < end_offset) { // emit the final 32-bit store
3101 Node* adr = new AddPNode(dest, dest, phase->MakeConX(done_offset));
3102 adr = phase->transform(adr);
3103 const TypePtr* atp = TypeRawPtr::BOTTOM;
3104 if (val != NULL) {
3105 assert(phase->type(val)->isa_narrowoop(), "should be narrow oop");
3106 mem = new StoreNNode(ctl, mem, adr, atp, val, MemNode::unordered);
3107 } else {
3108 assert(raw_val == NULL, "val may not be null");
3109 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
3110 }
3111 mem = phase->transform(mem);
3112 done_offset += BytesPerInt;
3113 }
3114 assert(done_offset == end_offset, "");
3115 return mem;
3116 }
3117
3118 //=============================================================================
3119 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
3120 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)),
3121 _adr_type(C->get_adr_type(alias_idx)), _kind(Standalone)
3122 #ifdef ASSERT
3123 , _pair_idx(0)
3124 #endif
3125 {
3126 init_class_id(Class_MemBar);
3127 Node* top = C->top();
3128 init_req(TypeFunc::I_O,top);
3129 init_req(TypeFunc::FramePtr,top);
3130 init_req(TypeFunc::ReturnAdr,top);
3131 if (precedent != NULL)
3132 init_req(TypeFunc::Parms, precedent);
3133 }
3134
3135 //------------------------------cmp--------------------------------------------
3136 uint MemBarNode::hash() const { return NO_HASH; }
3137 uint MemBarNode::cmp( const Node &n ) const {
3138 return (&n == this); // Always fail except on self
3139 }
3140
3141 //------------------------------make-------------------------------------------
3142 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
3143 switch (opcode) {
3144 case Op_MemBarAcquire: return new MemBarAcquireNode(C, atp, pn);
3145 case Op_LoadFence: return new LoadFenceNode(C, atp, pn);
3146 case Op_MemBarRelease: return new MemBarReleaseNode(C, atp, pn);
3147 case Op_StoreFence: return new StoreFenceNode(C, atp, pn);
3148 case Op_MemBarAcquireLock: return new MemBarAcquireLockNode(C, atp, pn);
3149 case Op_MemBarReleaseLock: return new MemBarReleaseLockNode(C, atp, pn);
3150 case Op_MemBarVolatile: return new MemBarVolatileNode(C, atp, pn);
3151 case Op_MemBarCPUOrder: return new MemBarCPUOrderNode(C, atp, pn);
3152 case Op_OnSpinWait: return new OnSpinWaitNode(C, atp, pn);
3153 case Op_Initialize: return new InitializeNode(C, atp, pn);
3154 case Op_MemBarStoreStore: return new MemBarStoreStoreNode(C, atp, pn);
3155 default: ShouldNotReachHere(); return NULL;
3156 }
3157 }
3158
3159 void MemBarNode::remove(PhaseIterGVN *igvn) {
3160 if (outcnt() != 2) {
3161 return;
3162 }
3163 if (trailing_store() || trailing_load_store()) {
3164 MemBarNode* leading = leading_membar();
3165 if (leading != NULL) {
3166 assert(leading->trailing_membar() == this, "inconsistent leading/trailing membars");
3167 leading->remove(igvn);
3168 }
3169 }
3170 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
3171 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
3172 }
3173
3174 //------------------------------Ideal------------------------------------------
3175 // Return a node which is more "ideal" than the current node. Strip out
3176 // control copies
3177 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3178 if (remove_dead_region(phase, can_reshape)) return this;
3179 // Don't bother trying to transform a dead node
3180 if (in(0) && in(0)->is_top()) {
3181 return NULL;
3182 }
3183
3184 #if INCLUDE_ZGC
3185 if (UseZGC) {
3186 if (req() == (Precedent+1) && in(MemBarNode::Precedent)->in(0) != NULL && in(MemBarNode::Precedent)->in(0)->is_LoadBarrier()) {
3187 Node* load_node = in(MemBarNode::Precedent)->in(0)->in(LoadBarrierNode::Oop);
3188 set_req(MemBarNode::Precedent, load_node);
3189 return this;
3190 }
3191 }
3192 #endif
3193
3194 bool progress = false;
3195 // Eliminate volatile MemBars for scalar replaced objects.
3196 if (can_reshape && req() == (Precedent+1)) {
3197 bool eliminate = false;
3198 int opc = Opcode();
3199 if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) {
3200 // Volatile field loads and stores.
3201 Node* my_mem = in(MemBarNode::Precedent);
3202 // The MembarAquire may keep an unused LoadNode alive through the Precedent edge
3203 if ((my_mem != NULL) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) {
3204 // if the Precedent is a decodeN and its input (a Load) is used at more than one place,
3205 // replace this Precedent (decodeN) with the Load instead.
3206 if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1)) {
3207 Node* load_node = my_mem->in(1);
3208 set_req(MemBarNode::Precedent, load_node);
3209 phase->is_IterGVN()->_worklist.push(my_mem);
3210 my_mem = load_node;
3211 } else {
3212 assert(my_mem->unique_out() == this, "sanity");
3213 del_req(Precedent);
3214 phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later
3215 my_mem = NULL;
3216 }
3217 progress = true;
3218 }
3219 if (my_mem != NULL && my_mem->is_Mem()) {
3220 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
3221 // Check for scalar replaced object reference.
3222 if( t_oop != NULL && t_oop->is_known_instance_field() &&
3223 t_oop->offset() != Type::OffsetBot &&
3224 t_oop->offset() != Type::OffsetTop) {
3225 eliminate = true;
3226 }
3227 }
3228 } else if (opc == Op_MemBarRelease) {
3229 // Final field stores.
3230 Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent), phase);
3231 if ((alloc != NULL) && alloc->is_Allocate() &&
3232 alloc->as_Allocate()->does_not_escape_thread()) {
3233 // The allocated object does not escape.
3234 eliminate = true;
3235 }
3236 }
3237 if (eliminate) {
3238 // Replace MemBar projections by its inputs.
3239 PhaseIterGVN* igvn = phase->is_IterGVN();
3240 remove(igvn);
3241 // Must return either the original node (now dead) or a new node
3242 // (Do not return a top here, since that would break the uniqueness of top.)
3243 return new ConINode(TypeInt::ZERO);
3244 }
3245 }
3246 return progress ? this : NULL;
3247 }
3248
3249 //------------------------------Value------------------------------------------
3250 const Type* MemBarNode::Value(PhaseGVN* phase) const {
3251 if( !in(0) ) return Type::TOP;
3252 if( phase->type(in(0)) == Type::TOP )
3253 return Type::TOP;
3254 return TypeTuple::MEMBAR;
3255 }
3256
3257 //------------------------------match------------------------------------------
3258 // Construct projections for memory.
3259 Node *MemBarNode::match(const ProjNode *proj, const Matcher *m, const RegMask* mask) {
3260 switch (proj->_con) {
3261 case TypeFunc::Control:
3262 case TypeFunc::Memory:
3263 return new MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
3264 }
3265 ShouldNotReachHere();
3266 return NULL;
3267 }
3268
3269 void MemBarNode::set_store_pair(MemBarNode* leading, MemBarNode* trailing) {
3270 trailing->_kind = TrailingStore;
3271 leading->_kind = LeadingStore;
3272 #ifdef ASSERT
3273 trailing->_pair_idx = leading->_idx;
3274 leading->_pair_idx = leading->_idx;
3275 #endif
3276 }
3277
3278 void MemBarNode::set_load_store_pair(MemBarNode* leading, MemBarNode* trailing) {
3279 trailing->_kind = TrailingLoadStore;
3280 leading->_kind = LeadingLoadStore;
3281 #ifdef ASSERT
3282 trailing->_pair_idx = leading->_idx;
3283 leading->_pair_idx = leading->_idx;
3284 #endif
3285 }
3286
3287 MemBarNode* MemBarNode::trailing_membar() const {
3288 ResourceMark rm;
3289 Node* trailing = (Node*)this;
3290 VectorSet seen(Thread::current()->resource_area());
3291 Node_Stack multis(0);
3292 do {
3293 Node* c = trailing;
3294 uint i = 0;
3295 do {
3296 trailing = NULL;
3297 for (; i < c->outcnt(); i++) {
3298 Node* next = c->raw_out(i);
3299 if (next != c && next->is_CFG()) {
3300 if (c->is_MultiBranch()) {
3301 if (multis.node() == c) {
3302 multis.set_index(i+1);
3303 } else {
3304 multis.push(c, i+1);
3305 }
3306 }
3307 trailing = next;
3308 break;
3309 }
3310 }
3311 if (trailing != NULL && !seen.test_set(trailing->_idx)) {
3312 break;
3313 }
3314 while (multis.size() > 0) {
3315 c = multis.node();
3316 i = multis.index();
3317 if (i < c->req()) {
3318 break;
3319 }
3320 multis.pop();
3321 }
3322 } while (multis.size() > 0);
3323 } while (!trailing->is_MemBar() || !trailing->as_MemBar()->trailing());
3324
3325 MemBarNode* mb = trailing->as_MemBar();
3326 assert((mb->_kind == TrailingStore && _kind == LeadingStore) ||
3327 (mb->_kind == TrailingLoadStore && _kind == LeadingLoadStore), "bad trailing membar");
3328 assert(mb->_pair_idx == _pair_idx, "bad trailing membar");
3329 return mb;
3330 }
3331
3332 MemBarNode* MemBarNode::leading_membar() const {
3333 ResourceMark rm;
3334 VectorSet seen(Thread::current()->resource_area());
3335 Node_Stack regions(0);
3336 Node* leading = in(0);
3337 while (leading != NULL && (!leading->is_MemBar() || !leading->as_MemBar()->leading())) {
3338 while (leading == NULL || leading->is_top() || seen.test_set(leading->_idx)) {
3339 leading = NULL;
3340 while (regions.size() > 0 && leading == NULL) {
3341 Node* r = regions.node();
3342 uint i = regions.index();
3343 if (i < r->req()) {
3344 leading = r->in(i);
3345 regions.set_index(i+1);
3346 } else {
3347 regions.pop();
3348 }
3349 }
3350 if (leading == NULL) {
3351 assert(regions.size() == 0, "all paths should have been tried");
3352 return NULL;
3353 }
3354 }
3355 if (leading->is_Region()) {
3356 regions.push(leading, 2);
3357 leading = leading->in(1);
3358 } else {
3359 leading = leading->in(0);
3360 }
3361 }
3362 #ifdef ASSERT
3363 Unique_Node_List wq;
3364 wq.push((Node*)this);
3365 uint found = 0;
3366 for (uint i = 0; i < wq.size(); i++) {
3367 Node* n = wq.at(i);
3368 if (n->is_Region()) {
3369 for (uint j = 1; j < n->req(); j++) {
3370 Node* in = n->in(j);
3371 if (in != NULL && !in->is_top()) {
3372 wq.push(in);
3373 }
3374 }
3375 } else {
3376 if (n->is_MemBar() && n->as_MemBar()->leading()) {
3377 assert(n == leading, "consistency check failed");
3378 found++;
3379 } else {
3380 Node* in = n->in(0);
3381 if (in != NULL && !in->is_top()) {
3382 wq.push(in);
3383 }
3384 }
3385 }
3386 }
3387 assert(found == 1 || (found == 0 && leading == NULL), "consistency check failed");
3388 #endif
3389 if (leading == NULL) {
3390 return NULL;
3391 }
3392 MemBarNode* mb = leading->as_MemBar();
3393 assert((mb->_kind == LeadingStore && _kind == TrailingStore) ||
3394 (mb->_kind == LeadingLoadStore && _kind == TrailingLoadStore), "bad leading membar");
3395 assert(mb->_pair_idx == _pair_idx, "bad leading membar");
3396 return mb;
3397 }
3398
3399 //===========================InitializeNode====================================
3400 // SUMMARY:
3401 // This node acts as a memory barrier on raw memory, after some raw stores.
3402 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
3403 // The Initialize can 'capture' suitably constrained stores as raw inits.
3404 // It can coalesce related raw stores into larger units (called 'tiles').
3405 // It can avoid zeroing new storage for memory units which have raw inits.
3406 // At macro-expansion, it is marked 'complete', and does not optimize further.
3407 //
3408 // EXAMPLE:
3409 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
3410 // ctl = incoming control; mem* = incoming memory
3411 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
3412 // First allocate uninitialized memory and fill in the header:
3413 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
3414 // ctl := alloc.Control; mem* := alloc.Memory*
3415 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
3416 // Then initialize to zero the non-header parts of the raw memory block:
3417 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
3418 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
3419 // After the initialize node executes, the object is ready for service:
3420 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
3421 // Suppose its body is immediately initialized as {1,2}:
3422 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3423 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3424 // mem.SLICE(#short[*]) := store2
3425 //
3426 // DETAILS:
3427 // An InitializeNode collects and isolates object initialization after
3428 // an AllocateNode and before the next possible safepoint. As a
3429 // memory barrier (MemBarNode), it keeps critical stores from drifting
3430 // down past any safepoint or any publication of the allocation.
3431 // Before this barrier, a newly-allocated object may have uninitialized bits.
3432 // After this barrier, it may be treated as a real oop, and GC is allowed.
3433 //
3434 // The semantics of the InitializeNode include an implicit zeroing of
3435 // the new object from object header to the end of the object.
3436 // (The object header and end are determined by the AllocateNode.)
3437 //
3438 // Certain stores may be added as direct inputs to the InitializeNode.
3439 // These stores must update raw memory, and they must be to addresses
3440 // derived from the raw address produced by AllocateNode, and with
3441 // a constant offset. They must be ordered by increasing offset.
3442 // The first one is at in(RawStores), the last at in(req()-1).
3443 // Unlike most memory operations, they are not linked in a chain,
3444 // but are displayed in parallel as users of the rawmem output of
3445 // the allocation.
3446 //
3447 // (See comments in InitializeNode::capture_store, which continue
3448 // the example given above.)
3449 //
3450 // When the associated Allocate is macro-expanded, the InitializeNode
3451 // may be rewritten to optimize collected stores. A ClearArrayNode
3452 // may also be created at that point to represent any required zeroing.
3453 // The InitializeNode is then marked 'complete', prohibiting further
3454 // capturing of nearby memory operations.
3455 //
3456 // During macro-expansion, all captured initializations which store
3457 // constant values of 32 bits or smaller are coalesced (if advantageous)
3458 // into larger 'tiles' 32 or 64 bits. This allows an object to be
3459 // initialized in fewer memory operations. Memory words which are
3460 // covered by neither tiles nor non-constant stores are pre-zeroed
3461 // by explicit stores of zero. (The code shape happens to do all
3462 // zeroing first, then all other stores, with both sequences occurring
3463 // in order of ascending offsets.)
3464 //
3465 // Alternatively, code may be inserted between an AllocateNode and its
3466 // InitializeNode, to perform arbitrary initialization of the new object.
3467 // E.g., the object copying intrinsics insert complex data transfers here.
3468 // The initialization must then be marked as 'complete' disable the
3469 // built-in zeroing semantics and the collection of initializing stores.
3470 //
3471 // While an InitializeNode is incomplete, reads from the memory state
3472 // produced by it are optimizable if they match the control edge and
3473 // new oop address associated with the allocation/initialization.
3474 // They return a stored value (if the offset matches) or else zero.
3475 // A write to the memory state, if it matches control and address,
3476 // and if it is to a constant offset, may be 'captured' by the
3477 // InitializeNode. It is cloned as a raw memory operation and rewired
3478 // inside the initialization, to the raw oop produced by the allocation.
3479 // Operations on addresses which are provably distinct (e.g., to
3480 // other AllocateNodes) are allowed to bypass the initialization.
3481 //
3482 // The effect of all this is to consolidate object initialization
3483 // (both arrays and non-arrays, both piecewise and bulk) into a
3484 // single location, where it can be optimized as a unit.
3485 //
3486 // Only stores with an offset less than TrackedInitializationLimit words
3487 // will be considered for capture by an InitializeNode. This puts a
3488 // reasonable limit on the complexity of optimized initializations.
3489
3490 //---------------------------InitializeNode------------------------------------
3491 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
3492 : MemBarNode(C, adr_type, rawoop),
3493 _is_complete(Incomplete), _does_not_escape(false)
3494 {
3495 init_class_id(Class_Initialize);
3496
3497 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
3498 assert(in(RawAddress) == rawoop, "proper init");
3499 // Note: allocation() can be NULL, for secondary initialization barriers
3500 }
3501
3502 // Since this node is not matched, it will be processed by the
3503 // register allocator. Declare that there are no constraints
3504 // on the allocation of the RawAddress edge.
3505 const RegMask &InitializeNode::in_RegMask(uint idx) const {
3506 // This edge should be set to top, by the set_complete. But be conservative.
3507 if (idx == InitializeNode::RawAddress)
3508 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
3509 return RegMask::Empty;
3510 }
3511
3512 Node* InitializeNode::memory(uint alias_idx) {
3513 Node* mem = in(Memory);
3514 if (mem->is_MergeMem()) {
3515 return mem->as_MergeMem()->memory_at(alias_idx);
3516 } else {
3517 // incoming raw memory is not split
3518 return mem;
3519 }
3520 }
3521
3522 bool InitializeNode::is_non_zero() {
3523 if (is_complete()) return false;
3524 remove_extra_zeroes();
3525 return (req() > RawStores);
3526 }
3527
3528 void InitializeNode::set_complete(PhaseGVN* phase) {
3529 assert(!is_complete(), "caller responsibility");
3530 _is_complete = Complete;
3531
3532 // After this node is complete, it contains a bunch of
3533 // raw-memory initializations. There is no need for
3534 // it to have anything to do with non-raw memory effects.
3535 // Therefore, tell all non-raw users to re-optimize themselves,
3536 // after skipping the memory effects of this initialization.
3537 PhaseIterGVN* igvn = phase->is_IterGVN();
3538 if (igvn) igvn->add_users_to_worklist(this);
3539 }
3540
3541 // convenience function
3542 // return false if the init contains any stores already
3543 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
3544 InitializeNode* init = initialization();
3545 if (init == NULL || init->is_complete()) {
3546 return false;
3547 }
3548 init->remove_extra_zeroes();
3549 // for now, if this allocation has already collected any inits, bail:
3550 if (init->is_non_zero()) return false;
3551 init->set_complete(phase);
3552 return true;
3553 }
3554
3555 void InitializeNode::remove_extra_zeroes() {
3556 if (req() == RawStores) return;
3557 Node* zmem = zero_memory();
3558 uint fill = RawStores;
3559 for (uint i = fill; i < req(); i++) {
3560 Node* n = in(i);
3561 if (n->is_top() || n == zmem) continue; // skip
3562 if (fill < i) set_req(fill, n); // compact
3563 ++fill;
3564 }
3565 // delete any empty spaces created:
3566 while (fill < req()) {
3567 del_req(fill);
3568 }
3569 }
3570
3571 // Helper for remembering which stores go with which offsets.
3572 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) {
3573 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
3574 intptr_t offset = -1;
3575 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
3576 phase, offset);
3577 if (base == NULL) return -1; // something is dead,
3578 if (offset < 0) return -1; // dead, dead
3579 return offset;
3580 }
3581
3582 // Helper for proving that an initialization expression is
3583 // "simple enough" to be folded into an object initialization.
3584 // Attempts to prove that a store's initial value 'n' can be captured
3585 // within the initialization without creating a vicious cycle, such as:
3586 // { Foo p = new Foo(); p.next = p; }
3587 // True for constants and parameters and small combinations thereof.
3588 bool InitializeNode::detect_init_independence(Node* n, int& count) {
3589 if (n == NULL) return true; // (can this really happen?)
3590 if (n->is_Proj()) n = n->in(0);
3591 if (n == this) return false; // found a cycle
3592 if (n->is_Con()) return true;
3593 if (n->is_Start()) return true; // params, etc., are OK
3594 if (n->is_Root()) return true; // even better
3595
3596 Node* ctl = n->in(0);
3597 if (ctl != NULL && !ctl->is_top()) {
3598 if (ctl->is_Proj()) ctl = ctl->in(0);
3599 if (ctl == this) return false;
3600
3601 // If we already know that the enclosing memory op is pinned right after
3602 // the init, then any control flow that the store has picked up
3603 // must have preceded the init, or else be equal to the init.
3604 // Even after loop optimizations (which might change control edges)
3605 // a store is never pinned *before* the availability of its inputs.
3606 if (!MemNode::all_controls_dominate(n, this))
3607 return false; // failed to prove a good control
3608 }
3609
3610 // Check data edges for possible dependencies on 'this'.
3611 if ((count += 1) > 20) return false; // complexity limit
3612 for (uint i = 1; i < n->req(); i++) {
3613 Node* m = n->in(i);
3614 if (m == NULL || m == n || m->is_top()) continue;
3615 uint first_i = n->find_edge(m);
3616 if (i != first_i) continue; // process duplicate edge just once
3617 if (!detect_init_independence(m, count)) {
3618 return false;
3619 }
3620 }
3621
3622 return true;
3623 }
3624
3625 // Here are all the checks a Store must pass before it can be moved into
3626 // an initialization. Returns zero if a check fails.
3627 // On success, returns the (constant) offset to which the store applies,
3628 // within the initialized memory.
3629 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase, bool can_reshape) {
3630 const int FAIL = 0;
3631 if (st->is_unaligned_access()) {
3632 return FAIL;
3633 }
3634 if (st->req() != MemNode::ValueIn + 1)
3635 return FAIL; // an inscrutable StoreNode (card mark?)
3636 Node* ctl = st->in(MemNode::Control);
3637 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this))
3638 return FAIL; // must be unconditional after the initialization
3639 Node* mem = st->in(MemNode::Memory);
3640 if (!(mem->is_Proj() && mem->in(0) == this))
3641 return FAIL; // must not be preceded by other stores
3642 Node* adr = st->in(MemNode::Address);
3643 intptr_t offset;
3644 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
3645 if (alloc == NULL)
3646 return FAIL; // inscrutable address
3647 if (alloc != allocation())
3648 return FAIL; // wrong allocation! (store needs to float up)
3649 Node* val = st->in(MemNode::ValueIn);
3650 int complexity_count = 0;
3651 if (!detect_init_independence(val, complexity_count))
3652 return FAIL; // stored value must be 'simple enough'
3653
3654 // The Store can be captured only if nothing after the allocation
3655 // and before the Store is using the memory location that the store
3656 // overwrites.
3657 bool failed = false;
3658 // If is_complete_with_arraycopy() is true the shape of the graph is
3659 // well defined and is safe so no need for extra checks.
3660 if (!is_complete_with_arraycopy()) {
3661 // We are going to look at each use of the memory state following
3662 // the allocation to make sure nothing reads the memory that the
3663 // Store writes.
3664 const TypePtr* t_adr = phase->type(adr)->isa_ptr();
3665 int alias_idx = phase->C->get_alias_index(t_adr);
3666 ResourceMark rm;
3667 Unique_Node_List mems;
3668 mems.push(mem);
3669 Node* unique_merge = NULL;
3670 for (uint next = 0; next < mems.size(); ++next) {
3671 Node *m = mems.at(next);
3672 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
3673 Node *n = m->fast_out(j);
3674 if (n->outcnt() == 0) {
3675 continue;
3676 }
3677 if (n == st) {
3678 continue;
3679 } else if (n->in(0) != NULL && n->in(0) != ctl) {
3680 // If the control of this use is different from the control
3681 // of the Store which is right after the InitializeNode then
3682 // this node cannot be between the InitializeNode and the
3683 // Store.
3684 continue;
3685 } else if (n->is_MergeMem()) {
3686 if (n->as_MergeMem()->memory_at(alias_idx) == m) {
3687 // We can hit a MergeMemNode (that will likely go away
3688 // later) that is a direct use of the memory state
3689 // following the InitializeNode on the same slice as the
3690 // store node that we'd like to capture. We need to check
3691 // the uses of the MergeMemNode.
3692 mems.push(n);
3693 }
3694 } else if (n->is_Mem()) {
3695 Node* other_adr = n->in(MemNode::Address);
3696 if (other_adr == adr) {
3697 failed = true;
3698 break;
3699 } else {
3700 const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr();
3701 if (other_t_adr != NULL) {
3702 int other_alias_idx = phase->C->get_alias_index(other_t_adr);
3703 if (other_alias_idx == alias_idx) {
3704 // A load from the same memory slice as the store right
3705 // after the InitializeNode. We check the control of the
3706 // object/array that is loaded from. If it's the same as
3707 // the store control then we cannot capture the store.
3708 assert(!n->is_Store(), "2 stores to same slice on same control?");
3709 Node* base = other_adr;
3710 assert(base->is_AddP(), "should be addp but is %s", base->Name());
3711 base = base->in(AddPNode::Base);
3712 if (base != NULL) {
3713 base = base->uncast();
3714 if (base->is_Proj() && base->in(0) == alloc) {
3715 failed = true;
3716 break;
3717 }
3718 }
3719 }
3720 }
3721 }
3722 } else {
3723 failed = true;
3724 break;
3725 }
3726 }
3727 }
3728 }
3729 if (failed) {
3730 if (!can_reshape) {
3731 // We decided we couldn't capture the store during parsing. We
3732 // should try again during the next IGVN once the graph is
3733 // cleaner.
3734 phase->C->record_for_igvn(st);
3735 }
3736 return FAIL;
3737 }
3738
3739 return offset; // success
3740 }
3741
3742 // Find the captured store in(i) which corresponds to the range
3743 // [start..start+size) in the initialized object.
3744 // If there is one, return its index i. If there isn't, return the
3745 // negative of the index where it should be inserted.
3746 // Return 0 if the queried range overlaps an initialization boundary
3747 // or if dead code is encountered.
3748 // If size_in_bytes is zero, do not bother with overlap checks.
3749 int InitializeNode::captured_store_insertion_point(intptr_t start,
3750 int size_in_bytes,
3751 PhaseTransform* phase) {
3752 const int FAIL = 0, MAX_STORE = BytesPerLong;
3753
3754 if (is_complete())
3755 return FAIL; // arraycopy got here first; punt
3756
3757 assert(allocation() != NULL, "must be present");
3758
3759 // no negatives, no header fields:
3760 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
3761
3762 // after a certain size, we bail out on tracking all the stores:
3763 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3764 if (start >= ti_limit) return FAIL;
3765
3766 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
3767 if (i >= limit) return -(int)i; // not found; here is where to put it
3768
3769 Node* st = in(i);
3770 intptr_t st_off = get_store_offset(st, phase);
3771 if (st_off < 0) {
3772 if (st != zero_memory()) {
3773 return FAIL; // bail out if there is dead garbage
3774 }
3775 } else if (st_off > start) {
3776 // ...we are done, since stores are ordered
3777 if (st_off < start + size_in_bytes) {
3778 return FAIL; // the next store overlaps
3779 }
3780 return -(int)i; // not found; here is where to put it
3781 } else if (st_off < start) {
3782 if (size_in_bytes != 0 &&
3783 start < st_off + MAX_STORE &&
3784 start < st_off + st->as_Store()->memory_size()) {
3785 return FAIL; // the previous store overlaps
3786 }
3787 } else {
3788 if (size_in_bytes != 0 &&
3789 st->as_Store()->memory_size() != size_in_bytes) {
3790 return FAIL; // mismatched store size
3791 }
3792 return i;
3793 }
3794
3795 ++i;
3796 }
3797 }
3798
3799 // Look for a captured store which initializes at the offset 'start'
3800 // with the given size. If there is no such store, and no other
3801 // initialization interferes, then return zero_memory (the memory
3802 // projection of the AllocateNode).
3803 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
3804 PhaseTransform* phase) {
3805 assert(stores_are_sane(phase), "");
3806 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3807 if (i == 0) {
3808 return NULL; // something is dead
3809 } else if (i < 0) {
3810 return zero_memory(); // just primordial zero bits here
3811 } else {
3812 Node* st = in(i); // here is the store at this position
3813 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
3814 return st;
3815 }
3816 }
3817
3818 // Create, as a raw pointer, an address within my new object at 'offset'.
3819 Node* InitializeNode::make_raw_address(intptr_t offset,
3820 PhaseTransform* phase) {
3821 Node* addr = in(RawAddress);
3822 if (offset != 0) {
3823 Compile* C = phase->C;
3824 addr = phase->transform( new AddPNode(C->top(), addr,
3825 phase->MakeConX(offset)) );
3826 }
3827 return addr;
3828 }
3829
3830 // Clone the given store, converting it into a raw store
3831 // initializing a field or element of my new object.
3832 // Caller is responsible for retiring the original store,
3833 // with subsume_node or the like.
3834 //
3835 // From the example above InitializeNode::InitializeNode,
3836 // here are the old stores to be captured:
3837 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3838 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3839 //
3840 // Here is the changed code; note the extra edges on init:
3841 // alloc = (Allocate ...)
3842 // rawoop = alloc.RawAddress
3843 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
3844 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
3845 // init = (Initialize alloc.Control alloc.Memory rawoop
3846 // rawstore1 rawstore2)
3847 //
3848 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
3849 PhaseTransform* phase, bool can_reshape) {
3850 assert(stores_are_sane(phase), "");
3851
3852 if (start < 0) return NULL;
3853 assert(can_capture_store(st, phase, can_reshape) == start, "sanity");
3854
3855 Compile* C = phase->C;
3856 int size_in_bytes = st->memory_size();
3857 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3858 if (i == 0) return NULL; // bail out
3859 Node* prev_mem = NULL; // raw memory for the captured store
3860 if (i > 0) {
3861 prev_mem = in(i); // there is a pre-existing store under this one
3862 set_req(i, C->top()); // temporarily disconnect it
3863 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
3864 } else {
3865 i = -i; // no pre-existing store
3866 prev_mem = zero_memory(); // a slice of the newly allocated object
3867 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
3868 set_req(--i, C->top()); // reuse this edge; it has been folded away
3869 else
3870 ins_req(i, C->top()); // build a new edge
3871 }
3872 Node* new_st = st->clone();
3873 new_st->set_req(MemNode::Control, in(Control));
3874 new_st->set_req(MemNode::Memory, prev_mem);
3875 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
3876 new_st = phase->transform(new_st);
3877
3878 // At this point, new_st might have swallowed a pre-existing store
3879 // at the same offset, or perhaps new_st might have disappeared,
3880 // if it redundantly stored the same value (or zero to fresh memory).
3881
3882 // In any case, wire it in:
3883 phase->igvn_rehash_node_delayed(this);
3884 set_req(i, new_st);
3885
3886 // The caller may now kill the old guy.
3887 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
3888 assert(check_st == new_st || check_st == NULL, "must be findable");
3889 assert(!is_complete(), "");
3890 return new_st;
3891 }
3892
3893 static bool store_constant(jlong* tiles, int num_tiles,
3894 intptr_t st_off, int st_size,
3895 jlong con) {
3896 if ((st_off & (st_size-1)) != 0)
3897 return false; // strange store offset (assume size==2**N)
3898 address addr = (address)tiles + st_off;
3899 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
3900 switch (st_size) {
3901 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
3902 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
3903 case sizeof(jint): *(jint*) addr = (jint) con; break;
3904 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
3905 default: return false; // strange store size (detect size!=2**N here)
3906 }
3907 return true; // return success to caller
3908 }
3909
3910 // Coalesce subword constants into int constants and possibly
3911 // into long constants. The goal, if the CPU permits,
3912 // is to initialize the object with a small number of 64-bit tiles.
3913 // Also, convert floating-point constants to bit patterns.
3914 // Non-constants are not relevant to this pass.
3915 //
3916 // In terms of the running example on InitializeNode::InitializeNode
3917 // and InitializeNode::capture_store, here is the transformation
3918 // of rawstore1 and rawstore2 into rawstore12:
3919 // alloc = (Allocate ...)
3920 // rawoop = alloc.RawAddress
3921 // tile12 = 0x00010002
3922 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
3923 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
3924 //
3925 void
3926 InitializeNode::coalesce_subword_stores(intptr_t header_size,
3927 Node* size_in_bytes,
3928 PhaseGVN* phase) {
3929 Compile* C = phase->C;
3930
3931 assert(stores_are_sane(phase), "");
3932 // Note: After this pass, they are not completely sane,
3933 // since there may be some overlaps.
3934
3935 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
3936
3937 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3938 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
3939 size_limit = MIN2(size_limit, ti_limit);
3940 size_limit = align_up(size_limit, BytesPerLong);
3941 int num_tiles = size_limit / BytesPerLong;
3942
3943 // allocate space for the tile map:
3944 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
3945 jlong tiles_buf[small_len];
3946 Node* nodes_buf[small_len];
3947 jlong inits_buf[small_len];
3948 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
3949 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3950 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
3951 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
3952 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
3953 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3954 // tiles: exact bitwise model of all primitive constants
3955 // nodes: last constant-storing node subsumed into the tiles model
3956 // inits: which bytes (in each tile) are touched by any initializations
3957
3958 //// Pass A: Fill in the tile model with any relevant stores.
3959
3960 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
3961 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
3962 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
3963 Node* zmem = zero_memory(); // initially zero memory state
3964 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3965 Node* st = in(i);
3966 intptr_t st_off = get_store_offset(st, phase);
3967
3968 // Figure out the store's offset and constant value:
3969 if (st_off < header_size) continue; //skip (ignore header)
3970 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
3971 int st_size = st->as_Store()->memory_size();
3972 if (st_off + st_size > size_limit) break;
3973
3974 // Record which bytes are touched, whether by constant or not.
3975 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
3976 continue; // skip (strange store size)
3977
3978 const Type* val = phase->type(st->in(MemNode::ValueIn));
3979 if (!val->singleton()) continue; //skip (non-con store)
3980 BasicType type = val->basic_type();
3981
3982 jlong con = 0;
3983 switch (type) {
3984 case T_INT: con = val->is_int()->get_con(); break;
3985 case T_LONG: con = val->is_long()->get_con(); break;
3986 case T_FLOAT: con = jint_cast(val->getf()); break;
3987 case T_DOUBLE: con = jlong_cast(val->getd()); break;
3988 default: continue; //skip (odd store type)
3989 }
3990
3991 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
3992 st->Opcode() == Op_StoreL) {
3993 continue; // This StoreL is already optimal.
3994 }
3995
3996 // Store down the constant.
3997 store_constant(tiles, num_tiles, st_off, st_size, con);
3998
3999 intptr_t j = st_off >> LogBytesPerLong;
4000
4001 if (type == T_INT && st_size == BytesPerInt
4002 && (st_off & BytesPerInt) == BytesPerInt) {
4003 jlong lcon = tiles[j];
4004 if (!Matcher::isSimpleConstant64(lcon) &&
4005 st->Opcode() == Op_StoreI) {
4006 // This StoreI is already optimal by itself.
4007 jint* intcon = (jint*) &tiles[j];
4008 intcon[1] = 0; // undo the store_constant()
4009
4010 // If the previous store is also optimal by itself, back up and
4011 // undo the action of the previous loop iteration... if we can.
4012 // But if we can't, just let the previous half take care of itself.
4013 st = nodes[j];
4014 st_off -= BytesPerInt;
4015 con = intcon[0];
4016 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) {
4017 assert(st_off >= header_size, "still ignoring header");
4018 assert(get_store_offset(st, phase) == st_off, "must be");
4019 assert(in(i-1) == zmem, "must be");
4020 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
4021 assert(con == tcon->is_int()->get_con(), "must be");
4022 // Undo the effects of the previous loop trip, which swallowed st:
4023 intcon[0] = 0; // undo store_constant()
4024 set_req(i-1, st); // undo set_req(i, zmem)
4025 nodes[j] = NULL; // undo nodes[j] = st
4026 --old_subword; // undo ++old_subword
4027 }
4028 continue; // This StoreI is already optimal.
4029 }
4030 }
4031
4032 // This store is not needed.
4033 set_req(i, zmem);
4034 nodes[j] = st; // record for the moment
4035 if (st_size < BytesPerLong) // something has changed
4036 ++old_subword; // includes int/float, but who's counting...
4037 else ++old_long;
4038 }
4039
4040 if ((old_subword + old_long) == 0)
4041 return; // nothing more to do
4042
4043 //// Pass B: Convert any non-zero tiles into optimal constant stores.
4044 // Be sure to insert them before overlapping non-constant stores.
4045 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
4046 for (int j = 0; j < num_tiles; j++) {
4047 jlong con = tiles[j];
4048 jlong init = inits[j];
4049 if (con == 0) continue;
4050 jint con0, con1; // split the constant, address-wise
4051 jint init0, init1; // split the init map, address-wise
4052 { union { jlong con; jint intcon[2]; } u;
4053 u.con = con;
4054 con0 = u.intcon[0];
4055 con1 = u.intcon[1];
4056 u.con = init;
4057 init0 = u.intcon[0];
4058 init1 = u.intcon[1];
4059 }
4060
4061 Node* old = nodes[j];
4062 assert(old != NULL, "need the prior store");
4063 intptr_t offset = (j * BytesPerLong);
4064
4065 bool split = !Matcher::isSimpleConstant64(con);
4066
4067 if (offset < header_size) {
4068 assert(offset + BytesPerInt >= header_size, "second int counts");
4069 assert(*(jint*)&tiles[j] == 0, "junk in header");
4070 split = true; // only the second word counts
4071 // Example: int a[] = { 42 ... }
4072 } else if (con0 == 0 && init0 == -1) {
4073 split = true; // first word is covered by full inits
4074 // Example: int a[] = { ... foo(), 42 ... }
4075 } else if (con1 == 0 && init1 == -1) {
4076 split = true; // second word is covered by full inits
4077 // Example: int a[] = { ... 42, foo() ... }
4078 }
4079
4080 // Here's a case where init0 is neither 0 nor -1:
4081 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
4082 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
4083 // In this case the tile is not split; it is (jlong)42.
4084 // The big tile is stored down, and then the foo() value is inserted.
4085 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
4086
4087 Node* ctl = old->in(MemNode::Control);
4088 Node* adr = make_raw_address(offset, phase);
4089 const TypePtr* atp = TypeRawPtr::BOTTOM;
4090
4091 // One or two coalesced stores to plop down.
4092 Node* st[2];
4093 intptr_t off[2];
4094 int nst = 0;
4095 if (!split) {
4096 ++new_long;
4097 off[nst] = offset;
4098 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
4099 phase->longcon(con), T_LONG, MemNode::unordered);
4100 } else {
4101 // Omit either if it is a zero.
4102 if (con0 != 0) {
4103 ++new_int;
4104 off[nst] = offset;
4105 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
4106 phase->intcon(con0), T_INT, MemNode::unordered);
4107 }
4108 if (con1 != 0) {
4109 ++new_int;
4110 offset += BytesPerInt;
4111 adr = make_raw_address(offset, phase);
4112 off[nst] = offset;
4113 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
4114 phase->intcon(con1), T_INT, MemNode::unordered);
4115 }
4116 }
4117
4118 // Insert second store first, then the first before the second.
4119 // Insert each one just before any overlapping non-constant stores.
4120 while (nst > 0) {
4121 Node* st1 = st[--nst];
4122 C->copy_node_notes_to(st1, old);
4123 st1 = phase->transform(st1);
4124 offset = off[nst];
4125 assert(offset >= header_size, "do not smash header");
4126 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
4127 guarantee(ins_idx != 0, "must re-insert constant store");
4128 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
4129 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
4130 set_req(--ins_idx, st1);
4131 else
4132 ins_req(ins_idx, st1);
4133 }
4134 }
4135
4136 if (PrintCompilation && WizardMode)
4137 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
4138 old_subword, old_long, new_int, new_long);
4139 if (C->log() != NULL)
4140 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
4141 old_subword, old_long, new_int, new_long);
4142
4143 // Clean up any remaining occurrences of zmem:
4144 remove_extra_zeroes();
4145 }
4146
4147 // Explore forward from in(start) to find the first fully initialized
4148 // word, and return its offset. Skip groups of subword stores which
4149 // together initialize full words. If in(start) is itself part of a
4150 // fully initialized word, return the offset of in(start). If there
4151 // are no following full-word stores, or if something is fishy, return
4152 // a negative value.
4153 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
4154 int int_map = 0;
4155 intptr_t int_map_off = 0;
4156 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
4157
4158 for (uint i = start, limit = req(); i < limit; i++) {
4159 Node* st = in(i);
4160
4161 intptr_t st_off = get_store_offset(st, phase);
4162 if (st_off < 0) break; // return conservative answer
4163
4164 int st_size = st->as_Store()->memory_size();
4165 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
4166 return st_off; // we found a complete word init
4167 }
4168
4169 // update the map:
4170
4171 intptr_t this_int_off = align_down(st_off, BytesPerInt);
4172 if (this_int_off != int_map_off) {
4173 // reset the map:
4174 int_map = 0;
4175 int_map_off = this_int_off;
4176 }
4177
4178 int subword_off = st_off - this_int_off;
4179 int_map |= right_n_bits(st_size) << subword_off;
4180 if ((int_map & FULL_MAP) == FULL_MAP) {
4181 return this_int_off; // we found a complete word init
4182 }
4183
4184 // Did this store hit or cross the word boundary?
4185 intptr_t next_int_off = align_down(st_off + st_size, BytesPerInt);
4186 if (next_int_off == this_int_off + BytesPerInt) {
4187 // We passed the current int, without fully initializing it.
4188 int_map_off = next_int_off;
4189 int_map >>= BytesPerInt;
4190 } else if (next_int_off > this_int_off + BytesPerInt) {
4191 // We passed the current and next int.
4192 return this_int_off + BytesPerInt;
4193 }
4194 }
4195
4196 return -1;
4197 }
4198
4199
4200 // Called when the associated AllocateNode is expanded into CFG.
4201 // At this point, we may perform additional optimizations.
4202 // Linearize the stores by ascending offset, to make memory
4203 // activity as coherent as possible.
4204 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
4205 intptr_t header_size,
4206 Node* size_in_bytes,
4207 PhaseGVN* phase) {
4208 assert(!is_complete(), "not already complete");
4209 assert(stores_are_sane(phase), "");
4210 assert(allocation() != NULL, "must be present");
4211
4212 remove_extra_zeroes();
4213
4214 if (ReduceFieldZeroing || ReduceBulkZeroing)
4215 // reduce instruction count for common initialization patterns
4216 coalesce_subword_stores(header_size, size_in_bytes, phase);
4217
4218 Node* zmem = zero_memory(); // initially zero memory state
4219 Node* inits = zmem; // accumulating a linearized chain of inits
4220 #ifdef ASSERT
4221 intptr_t first_offset = allocation()->minimum_header_size();
4222 intptr_t last_init_off = first_offset; // previous init offset
4223 intptr_t last_init_end = first_offset; // previous init offset+size
4224 intptr_t last_tile_end = first_offset; // previous tile offset+size
4225 #endif
4226 intptr_t zeroes_done = header_size;
4227
4228 bool do_zeroing = true; // we might give up if inits are very sparse
4229 int big_init_gaps = 0; // how many large gaps have we seen?
4230
4231 if (UseTLAB && ZeroTLAB) do_zeroing = false;
4232 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
4233
4234 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
4235 Node* st = in(i);
4236 intptr_t st_off = get_store_offset(st, phase);
4237 if (st_off < 0)
4238 break; // unknown junk in the inits
4239 if (st->in(MemNode::Memory) != zmem)
4240 break; // complicated store chains somehow in list
4241
4242 int st_size = st->as_Store()->memory_size();
4243 intptr_t next_init_off = st_off + st_size;
4244
4245 if (do_zeroing && zeroes_done < next_init_off) {
4246 // See if this store needs a zero before it or under it.
4247 intptr_t zeroes_needed = st_off;
4248
4249 if (st_size < BytesPerInt) {
4250 // Look for subword stores which only partially initialize words.
4251 // If we find some, we must lay down some word-level zeroes first,
4252 // underneath the subword stores.
4253 //
4254 // Examples:
4255 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
4256 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
4257 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
4258 //
4259 // Note: coalesce_subword_stores may have already done this,
4260 // if it was prompted by constant non-zero subword initializers.
4261 // But this case can still arise with non-constant stores.
4262
4263 intptr_t next_full_store = find_next_fullword_store(i, phase);
4264
4265 // In the examples above:
4266 // in(i) p q r s x y z
4267 // st_off 12 13 14 15 12 13 14
4268 // st_size 1 1 1 1 1 1 1
4269 // next_full_s. 12 16 16 16 16 16 16
4270 // z's_done 12 16 16 16 12 16 12
4271 // z's_needed 12 16 16 16 16 16 16
4272 // zsize 0 0 0 0 4 0 4
4273 if (next_full_store < 0) {
4274 // Conservative tack: Zero to end of current word.
4275 zeroes_needed = align_up(zeroes_needed, BytesPerInt);
4276 } else {
4277 // Zero to beginning of next fully initialized word.
4278 // Or, don't zero at all, if we are already in that word.
4279 assert(next_full_store >= zeroes_needed, "must go forward");
4280 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
4281 zeroes_needed = next_full_store;
4282 }
4283 }
4284
4285 if (zeroes_needed > zeroes_done) {
4286 intptr_t zsize = zeroes_needed - zeroes_done;
4287 // Do some incremental zeroing on rawmem, in parallel with inits.
4288 zeroes_done = align_down(zeroes_done, BytesPerInt);
4289 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
4290 allocation()->in(AllocateNode::DefaultValue),
4291 allocation()->in(AllocateNode::RawDefaultValue),
4292 zeroes_done, zeroes_needed,
4293 phase);
4294 zeroes_done = zeroes_needed;
4295 if (zsize > InitArrayShortSize && ++big_init_gaps > 2)
4296 do_zeroing = false; // leave the hole, next time
4297 }
4298 }
4299
4300 // Collect the store and move on:
4301 st->set_req(MemNode::Memory, inits);
4302 inits = st; // put it on the linearized chain
4303 set_req(i, zmem); // unhook from previous position
4304
4305 if (zeroes_done == st_off)
4306 zeroes_done = next_init_off;
4307
4308 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
4309
4310 #ifdef ASSERT
4311 // Various order invariants. Weaker than stores_are_sane because
4312 // a large constant tile can be filled in by smaller non-constant stores.
4313 assert(st_off >= last_init_off, "inits do not reverse");
4314 last_init_off = st_off;
4315 const Type* val = NULL;
4316 if (st_size >= BytesPerInt &&
4317 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
4318 (int)val->basic_type() < (int)T_OBJECT) {
4319 assert(st_off >= last_tile_end, "tiles do not overlap");
4320 assert(st_off >= last_init_end, "tiles do not overwrite inits");
4321 last_tile_end = MAX2(last_tile_end, next_init_off);
4322 } else {
4323 intptr_t st_tile_end = align_up(next_init_off, BytesPerLong);
4324 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
4325 assert(st_off >= last_init_end, "inits do not overlap");
4326 last_init_end = next_init_off; // it's a non-tile
4327 }
4328 #endif //ASSERT
4329 }
4330
4331 remove_extra_zeroes(); // clear out all the zmems left over
4332 add_req(inits);
4333
4334 if (!(UseTLAB && ZeroTLAB)) {
4335 // If anything remains to be zeroed, zero it all now.
4336 zeroes_done = align_down(zeroes_done, BytesPerInt);
4337 // if it is the last unused 4 bytes of an instance, forget about it
4338 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
4339 if (zeroes_done + BytesPerLong >= size_limit) {
4340 AllocateNode* alloc = allocation();
4341 assert(alloc != NULL, "must be present");
4342 if (alloc != NULL && alloc->Opcode() == Op_Allocate) {
4343 Node* klass_node = alloc->in(AllocateNode::KlassNode);
4344 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass();
4345 if (zeroes_done == k->layout_helper())
4346 zeroes_done = size_limit;
4347 }
4348 }
4349 if (zeroes_done < size_limit) {
4350 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
4351 allocation()->in(AllocateNode::DefaultValue),
4352 allocation()->in(AllocateNode::RawDefaultValue),
4353 zeroes_done, size_in_bytes, phase);
4354 }
4355 }
4356
4357 set_complete(phase);
4358 return rawmem;
4359 }
4360
4361
4362 #ifdef ASSERT
4363 bool InitializeNode::stores_are_sane(PhaseTransform* phase) {
4364 if (is_complete())
4365 return true; // stores could be anything at this point
4366 assert(allocation() != NULL, "must be present");
4367 intptr_t last_off = allocation()->minimum_header_size();
4368 for (uint i = InitializeNode::RawStores; i < req(); i++) {
4369 Node* st = in(i);
4370 intptr_t st_off = get_store_offset(st, phase);
4371 if (st_off < 0) continue; // ignore dead garbage
4372 if (last_off > st_off) {
4373 tty->print_cr("*** bad store offset at %d: " INTX_FORMAT " > " INTX_FORMAT, i, last_off, st_off);
4374 this->dump(2);
4375 assert(false, "ascending store offsets");
4376 return false;
4377 }
4378 last_off = st_off + st->as_Store()->memory_size();
4379 }
4380 return true;
4381 }
4382 #endif //ASSERT
4383
4384
4385
4386
4387 //============================MergeMemNode=====================================
4388 //
4389 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
4390 // contributing store or call operations. Each contributor provides the memory
4391 // state for a particular "alias type" (see Compile::alias_type). For example,
4392 // if a MergeMem has an input X for alias category #6, then any memory reference
4393 // to alias category #6 may use X as its memory state input, as an exact equivalent
4394 // to using the MergeMem as a whole.
4395 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
4396 //
4397 // (Here, the <N> notation gives the index of the relevant adr_type.)
4398 //
4399 // In one special case (and more cases in the future), alias categories overlap.
4400 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
4401 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
4402 // it is exactly equivalent to that state W:
4403 // MergeMem(<Bot>: W) <==> W
4404 //
4405 // Usually, the merge has more than one input. In that case, where inputs
4406 // overlap (i.e., one is Bot), the narrower alias type determines the memory
4407 // state for that type, and the wider alias type (Bot) fills in everywhere else:
4408 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
4409 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
4410 //
4411 // A merge can take a "wide" memory state as one of its narrow inputs.
4412 // This simply means that the merge observes out only the relevant parts of
4413 // the wide input. That is, wide memory states arriving at narrow merge inputs
4414 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
4415 //
4416 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
4417 // and that memory slices "leak through":
4418 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
4419 //
4420 // But, in such a cascade, repeated memory slices can "block the leak":
4421 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
4422 //
4423 // In the last example, Y is not part of the combined memory state of the
4424 // outermost MergeMem. The system must, of course, prevent unschedulable
4425 // memory states from arising, so you can be sure that the state Y is somehow
4426 // a precursor to state Y'.
4427 //
4428 //
4429 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
4430 // of each MergeMemNode array are exactly the numerical alias indexes, including
4431 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
4432 // Compile::alias_type (and kin) produce and manage these indexes.
4433 //
4434 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
4435 // (Note that this provides quick access to the top node inside MergeMem methods,
4436 // without the need to reach out via TLS to Compile::current.)
4437 //
4438 // As a consequence of what was just described, a MergeMem that represents a full
4439 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
4440 // containing all alias categories.
4441 //
4442 // MergeMem nodes never (?) have control inputs, so in(0) is NULL.
4443 //
4444 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
4445 // a memory state for the alias type <N>, or else the top node, meaning that
4446 // there is no particular input for that alias type. Note that the length of
4447 // a MergeMem is variable, and may be extended at any time to accommodate new
4448 // memory states at larger alias indexes. When merges grow, they are of course
4449 // filled with "top" in the unused in() positions.
4450 //
4451 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
4452 // (Top was chosen because it works smoothly with passes like GCM.)
4453 //
4454 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
4455 // the type of random VM bits like TLS references.) Since it is always the
4456 // first non-Bot memory slice, some low-level loops use it to initialize an
4457 // index variable: for (i = AliasIdxRaw; i < req(); i++).
4458 //
4459 //
4460 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
4461 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
4462 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
4463 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
4464 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
4465 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
4466 //
4467 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
4468 // really that different from the other memory inputs. An abbreviation called
4469 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
4470 //
4471 //
4472 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
4473 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
4474 // that "emerges though" the base memory will be marked as excluding the alias types
4475 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
4476 //
4477 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
4478 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
4479 //
4480 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
4481 // (It is currently unimplemented.) As you can see, the resulting merge is
4482 // actually a disjoint union of memory states, rather than an overlay.
4483 //
4484
4485 //------------------------------MergeMemNode-----------------------------------
4486 Node* MergeMemNode::make_empty_memory() {
4487 Node* empty_memory = (Node*) Compile::current()->top();
4488 assert(empty_memory->is_top(), "correct sentinel identity");
4489 return empty_memory;
4490 }
4491
4492 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
4493 init_class_id(Class_MergeMem);
4494 // all inputs are nullified in Node::Node(int)
4495 // set_input(0, NULL); // no control input
4496
4497 // Initialize the edges uniformly to top, for starters.
4498 Node* empty_mem = make_empty_memory();
4499 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
4500 init_req(i,empty_mem);
4501 }
4502 assert(empty_memory() == empty_mem, "");
4503
4504 if( new_base != NULL && new_base->is_MergeMem() ) {
4505 MergeMemNode* mdef = new_base->as_MergeMem();
4506 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
4507 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
4508 mms.set_memory(mms.memory2());
4509 }
4510 assert(base_memory() == mdef->base_memory(), "");
4511 } else {
4512 set_base_memory(new_base);
4513 }
4514 }
4515
4516 // Make a new, untransformed MergeMem with the same base as 'mem'.
4517 // If mem is itself a MergeMem, populate the result with the same edges.
4518 MergeMemNode* MergeMemNode::make(Node* mem) {
4519 return new MergeMemNode(mem);
4520 }
4521
4522 //------------------------------cmp--------------------------------------------
4523 uint MergeMemNode::hash() const { return NO_HASH; }
4524 uint MergeMemNode::cmp( const Node &n ) const {
4525 return (&n == this); // Always fail except on self
4526 }
4527
4528 //------------------------------Identity---------------------------------------
4529 Node* MergeMemNode::Identity(PhaseGVN* phase) {
4530 // Identity if this merge point does not record any interesting memory
4531 // disambiguations.
4532 Node* base_mem = base_memory();
4533 Node* empty_mem = empty_memory();
4534 if (base_mem != empty_mem) { // Memory path is not dead?
4535 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4536 Node* mem = in(i);
4537 if (mem != empty_mem && mem != base_mem) {
4538 return this; // Many memory splits; no change
4539 }
4540 }
4541 }
4542 return base_mem; // No memory splits; ID on the one true input
4543 }
4544
4545 //------------------------------Ideal------------------------------------------
4546 // This method is invoked recursively on chains of MergeMem nodes
4547 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4548 // Remove chain'd MergeMems
4549 //
4550 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
4551 // relative to the "in(Bot)". Since we are patching both at the same time,
4552 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
4553 // but rewrite each "in(i)" relative to the new "in(Bot)".
4554 Node *progress = NULL;
4555
4556
4557 Node* old_base = base_memory();
4558 Node* empty_mem = empty_memory();
4559 if (old_base == empty_mem)
4560 return NULL; // Dead memory path.
4561
4562 MergeMemNode* old_mbase;
4563 if (old_base != NULL && old_base->is_MergeMem())
4564 old_mbase = old_base->as_MergeMem();
4565 else
4566 old_mbase = NULL;
4567 Node* new_base = old_base;
4568
4569 // simplify stacked MergeMems in base memory
4570 if (old_mbase) new_base = old_mbase->base_memory();
4571
4572 // the base memory might contribute new slices beyond my req()
4573 if (old_mbase) grow_to_match(old_mbase);
4574
4575 // Look carefully at the base node if it is a phi.
4576 PhiNode* phi_base;
4577 if (new_base != NULL && new_base->is_Phi())
4578 phi_base = new_base->as_Phi();
4579 else
4580 phi_base = NULL;
4581
4582 Node* phi_reg = NULL;
4583 uint phi_len = (uint)-1;
4584 if (phi_base != NULL && !phi_base->is_copy()) {
4585 // do not examine phi if degraded to a copy
4586 phi_reg = phi_base->region();
4587 phi_len = phi_base->req();
4588 // see if the phi is unfinished
4589 for (uint i = 1; i < phi_len; i++) {
4590 if (phi_base->in(i) == NULL) {
4591 // incomplete phi; do not look at it yet!
4592 phi_reg = NULL;
4593 phi_len = (uint)-1;
4594 break;
4595 }
4596 }
4597 }
4598
4599 // Note: We do not call verify_sparse on entry, because inputs
4600 // can normalize to the base_memory via subsume_node or similar
4601 // mechanisms. This method repairs that damage.
4602
4603 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
4604
4605 // Look at each slice.
4606 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4607 Node* old_in = in(i);
4608 // calculate the old memory value
4609 Node* old_mem = old_in;
4610 if (old_mem == empty_mem) old_mem = old_base;
4611 assert(old_mem == memory_at(i), "");
4612
4613 // maybe update (reslice) the old memory value
4614
4615 // simplify stacked MergeMems
4616 Node* new_mem = old_mem;
4617 MergeMemNode* old_mmem;
4618 if (old_mem != NULL && old_mem->is_MergeMem())
4619 old_mmem = old_mem->as_MergeMem();
4620 else
4621 old_mmem = NULL;
4622 if (old_mmem == this) {
4623 // This can happen if loops break up and safepoints disappear.
4624 // A merge of BotPtr (default) with a RawPtr memory derived from a
4625 // safepoint can be rewritten to a merge of the same BotPtr with
4626 // the BotPtr phi coming into the loop. If that phi disappears
4627 // also, we can end up with a self-loop of the mergemem.
4628 // In general, if loops degenerate and memory effects disappear,
4629 // a mergemem can be left looking at itself. This simply means
4630 // that the mergemem's default should be used, since there is
4631 // no longer any apparent effect on this slice.
4632 // Note: If a memory slice is a MergeMem cycle, it is unreachable
4633 // from start. Update the input to TOP.
4634 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
4635 }
4636 else if (old_mmem != NULL) {
4637 new_mem = old_mmem->memory_at(i);
4638 }
4639 // else preceding memory was not a MergeMem
4640
4641 // replace equivalent phis (unfortunately, they do not GVN together)
4642 if (new_mem != NULL && new_mem != new_base &&
4643 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) {
4644 if (new_mem->is_Phi()) {
4645 PhiNode* phi_mem = new_mem->as_Phi();
4646 for (uint i = 1; i < phi_len; i++) {
4647 if (phi_base->in(i) != phi_mem->in(i)) {
4648 phi_mem = NULL;
4649 break;
4650 }
4651 }
4652 if (phi_mem != NULL) {
4653 // equivalent phi nodes; revert to the def
4654 new_mem = new_base;
4655 }
4656 }
4657 }
4658
4659 // maybe store down a new value
4660 Node* new_in = new_mem;
4661 if (new_in == new_base) new_in = empty_mem;
4662
4663 if (new_in != old_in) {
4664 // Warning: Do not combine this "if" with the previous "if"
4665 // A memory slice might have be be rewritten even if it is semantically
4666 // unchanged, if the base_memory value has changed.
4667 set_req(i, new_in);
4668 progress = this; // Report progress
4669 }
4670 }
4671
4672 if (new_base != old_base) {
4673 set_req(Compile::AliasIdxBot, new_base);
4674 // Don't use set_base_memory(new_base), because we need to update du.
4675 assert(base_memory() == new_base, "");
4676 progress = this;
4677 }
4678
4679 if( base_memory() == this ) {
4680 // a self cycle indicates this memory path is dead
4681 set_req(Compile::AliasIdxBot, empty_mem);
4682 }
4683
4684 // Resolve external cycles by calling Ideal on a MergeMem base_memory
4685 // Recursion must occur after the self cycle check above
4686 if( base_memory()->is_MergeMem() ) {
4687 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
4688 Node *m = phase->transform(new_mbase); // Rollup any cycles
4689 if( m != NULL &&
4690 (m->is_top() ||
4691 (m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem)) ) {
4692 // propagate rollup of dead cycle to self
4693 set_req(Compile::AliasIdxBot, empty_mem);
4694 }
4695 }
4696
4697 if( base_memory() == empty_mem ) {
4698 progress = this;
4699 // Cut inputs during Parse phase only.
4700 // During Optimize phase a dead MergeMem node will be subsumed by Top.
4701 if( !can_reshape ) {
4702 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4703 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
4704 }
4705 }
4706 }
4707
4708 if( !progress && base_memory()->is_Phi() && can_reshape ) {
4709 // Check if PhiNode::Ideal's "Split phis through memory merges"
4710 // transform should be attempted. Look for this->phi->this cycle.
4711 uint merge_width = req();
4712 if (merge_width > Compile::AliasIdxRaw) {
4713 PhiNode* phi = base_memory()->as_Phi();
4714 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
4715 if (phi->in(i) == this) {
4716 phase->is_IterGVN()->_worklist.push(phi);
4717 break;
4718 }
4719 }
4720 }
4721 }
4722
4723 assert(progress || verify_sparse(), "please, no dups of base");
4724 return progress;
4725 }
4726
4727 //-------------------------set_base_memory-------------------------------------
4728 void MergeMemNode::set_base_memory(Node *new_base) {
4729 Node* empty_mem = empty_memory();
4730 set_req(Compile::AliasIdxBot, new_base);
4731 assert(memory_at(req()) == new_base, "must set default memory");
4732 // Clear out other occurrences of new_base:
4733 if (new_base != empty_mem) {
4734 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4735 if (in(i) == new_base) set_req(i, empty_mem);
4736 }
4737 }
4738 }
4739
4740 //------------------------------out_RegMask------------------------------------
4741 const RegMask &MergeMemNode::out_RegMask() const {
4742 return RegMask::Empty;
4743 }
4744
4745 //------------------------------dump_spec--------------------------------------
4746 #ifndef PRODUCT
4747 void MergeMemNode::dump_spec(outputStream *st) const {
4748 st->print(" {");
4749 Node* base_mem = base_memory();
4750 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
4751 Node* mem = (in(i) != NULL) ? memory_at(i) : base_mem;
4752 if (mem == base_mem) { st->print(" -"); continue; }
4753 st->print( " N%d:", mem->_idx );
4754 Compile::current()->get_adr_type(i)->dump_on(st);
4755 }
4756 st->print(" }");
4757 }
4758 #endif // !PRODUCT
4759
4760
4761 #ifdef ASSERT
4762 static bool might_be_same(Node* a, Node* b) {
4763 if (a == b) return true;
4764 if (!(a->is_Phi() || b->is_Phi())) return false;
4765 // phis shift around during optimization
4766 return true; // pretty stupid...
4767 }
4768
4769 // verify a narrow slice (either incoming or outgoing)
4770 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
4771 if (!VerifyAliases) return; // don't bother to verify unless requested
4772 if (VMError::is_error_reported()) return; // muzzle asserts when debugging an error
4773 if (Node::in_dump()) return; // muzzle asserts when printing
4774 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
4775 assert(n != NULL, "");
4776 // Elide intervening MergeMem's
4777 while (n->is_MergeMem()) {
4778 n = n->as_MergeMem()->memory_at(alias_idx);
4779 }
4780 Compile* C = Compile::current();
4781 const TypePtr* n_adr_type = n->adr_type();
4782 if (n == m->empty_memory()) {
4783 // Implicit copy of base_memory()
4784 } else if (n_adr_type != TypePtr::BOTTOM) {
4785 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type");
4786 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
4787 } else {
4788 // A few places like make_runtime_call "know" that VM calls are narrow,
4789 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
4790 bool expected_wide_mem = false;
4791 if (n == m->base_memory()) {
4792 expected_wide_mem = true;
4793 } else if (alias_idx == Compile::AliasIdxRaw ||
4794 n == m->memory_at(Compile::AliasIdxRaw)) {
4795 expected_wide_mem = true;
4796 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
4797 // memory can "leak through" calls on channels that
4798 // are write-once. Allow this also.
4799 expected_wide_mem = true;
4800 }
4801 assert(expected_wide_mem, "expected narrow slice replacement");
4802 }
4803 }
4804 #else // !ASSERT
4805 #define verify_memory_slice(m,i,n) (void)(0) // PRODUCT version is no-op
4806 #endif
4807
4808
4809 //-----------------------------memory_at---------------------------------------
4810 Node* MergeMemNode::memory_at(uint alias_idx) const {
4811 assert(alias_idx >= Compile::AliasIdxRaw ||
4812 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0,
4813 "must avoid base_memory and AliasIdxTop");
4814
4815 // Otherwise, it is a narrow slice.
4816 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
4817 Compile *C = Compile::current();
4818 if (is_empty_memory(n)) {
4819 // the array is sparse; empty slots are the "top" node
4820 n = base_memory();
4821 assert(Node::in_dump()
4822 || n == NULL || n->bottom_type() == Type::TOP
4823 || n->adr_type() == NULL // address is TOP
4824 || n->adr_type() == TypePtr::BOTTOM
4825 || n->adr_type() == TypeRawPtr::BOTTOM
4826 || Compile::current()->AliasLevel() == 0,
4827 "must be a wide memory");
4828 // AliasLevel == 0 if we are organizing the memory states manually.
4829 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
4830 } else {
4831 // make sure the stored slice is sane
4832 #ifdef ASSERT
4833 if (VMError::is_error_reported() || Node::in_dump()) {
4834 } else if (might_be_same(n, base_memory())) {
4835 // Give it a pass: It is a mostly harmless repetition of the base.
4836 // This can arise normally from node subsumption during optimization.
4837 } else {
4838 verify_memory_slice(this, alias_idx, n);
4839 }
4840 #endif
4841 }
4842 return n;
4843 }
4844
4845 //---------------------------set_memory_at-------------------------------------
4846 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
4847 verify_memory_slice(this, alias_idx, n);
4848 Node* empty_mem = empty_memory();
4849 if (n == base_memory()) n = empty_mem; // collapse default
4850 uint need_req = alias_idx+1;
4851 if (req() < need_req) {
4852 if (n == empty_mem) return; // already the default, so do not grow me
4853 // grow the sparse array
4854 do {
4855 add_req(empty_mem);
4856 } while (req() < need_req);
4857 }
4858 set_req( alias_idx, n );
4859 }
4860
4861
4862
4863 //--------------------------iteration_setup------------------------------------
4864 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
4865 if (other != NULL) {
4866 grow_to_match(other);
4867 // invariant: the finite support of mm2 is within mm->req()
4868 #ifdef ASSERT
4869 for (uint i = req(); i < other->req(); i++) {
4870 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
4871 }
4872 #endif
4873 }
4874 // Replace spurious copies of base_memory by top.
4875 Node* base_mem = base_memory();
4876 if (base_mem != NULL && !base_mem->is_top()) {
4877 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
4878 if (in(i) == base_mem)
4879 set_req(i, empty_memory());
4880 }
4881 }
4882 }
4883
4884 //---------------------------grow_to_match-------------------------------------
4885 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
4886 Node* empty_mem = empty_memory();
4887 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
4888 // look for the finite support of the other memory
4889 for (uint i = other->req(); --i >= req(); ) {
4890 if (other->in(i) != empty_mem) {
4891 uint new_len = i+1;
4892 while (req() < new_len) add_req(empty_mem);
4893 break;
4894 }
4895 }
4896 }
4897
4898 //---------------------------verify_sparse-------------------------------------
4899 #ifndef PRODUCT
4900 bool MergeMemNode::verify_sparse() const {
4901 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
4902 Node* base_mem = base_memory();
4903 // The following can happen in degenerate cases, since empty==top.
4904 if (is_empty_memory(base_mem)) return true;
4905 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4906 assert(in(i) != NULL, "sane slice");
4907 if (in(i) == base_mem) return false; // should have been the sentinel value!
4908 }
4909 return true;
4910 }
4911
4912 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
4913 Node* n;
4914 n = mm->in(idx);
4915 if (mem == n) return true; // might be empty_memory()
4916 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
4917 if (mem == n) return true;
4918 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) {
4919 if (mem == n) return true;
4920 if (n == NULL) break;
4921 }
4922 return false;
4923 }
4924 #endif // !PRODUCT