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