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