1 /*
2 * Copyright (c) 1997, 2016, 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.
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23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/systemDictionary.hpp"
27 #include "compiler/compileLog.hpp"
28 #include "memory/allocation.inline.hpp"
29 #include "oops/objArrayKlass.hpp"
30 #include "opto/addnode.hpp"
31 #include "opto/cfgnode.hpp"
32 #include "opto/compile.hpp"
33 #include "opto/connode.hpp"
34 #include "opto/loopnode.hpp"
35 #include "opto/machnode.hpp"
36 #include "opto/matcher.hpp"
37 #include "opto/memnode.hpp"
38 #include "opto/mulnode.hpp"
39 #include "opto/phaseX.hpp"
40 #include "opto/regmask.hpp"
41
42 // Portions of code courtesy of Clifford Click
43
44 // Optimization - Graph Style
45
46 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st);
47
48 //=============================================================================
49 uint MemNode::size_of() const { return sizeof(*this); }
50
51 const TypePtr *MemNode::adr_type() const {
52 Node* adr = in(Address);
53 const TypePtr* cross_check = NULL;
54 DEBUG_ONLY(cross_check = _adr_type);
55 return calculate_adr_type(adr->bottom_type(), cross_check);
56 }
57
58 #ifndef PRODUCT
59 void MemNode::dump_spec(outputStream *st) const {
60 if (in(Address) == NULL) return; // node is dead
61 #ifndef ASSERT
62 // fake the missing field
63 const TypePtr* _adr_type = NULL;
64 if (in(Address) != NULL)
65 _adr_type = in(Address)->bottom_type()->isa_ptr();
66 #endif
67 dump_adr_type(this, _adr_type, st);
68
69 Compile* C = Compile::current();
70 if (C->alias_type(_adr_type)->is_volatile()) {
71 st->print(" Volatile!");
72 }
73 if (_unaligned_access) {
74 st->print(" unaligned");
75 }
76 if (_mismatched_access) {
77 st->print(" mismatched");
78 }
79 }
80
81 void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) {
82 st->print(" @");
83 if (adr_type == NULL) {
84 st->print("NULL");
85 } else {
86 adr_type->dump_on(st);
87 Compile* C = Compile::current();
88 Compile::AliasType* atp = NULL;
89 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type);
90 if (atp == NULL)
91 st->print(", idx=?\?;");
92 else if (atp->index() == Compile::AliasIdxBot)
93 st->print(", idx=Bot;");
94 else if (atp->index() == Compile::AliasIdxTop)
95 st->print(", idx=Top;");
96 else if (atp->index() == Compile::AliasIdxRaw)
97 st->print(", idx=Raw;");
98 else {
99 ciField* field = atp->field();
100 if (field) {
101 st->print(", name=");
102 field->print_name_on(st);
103 }
104 st->print(", idx=%d;", atp->index());
105 }
106 }
107 }
108
109 extern void print_alias_types();
110
111 #endif
112
113 Node *MemNode::optimize_simple_memory_chain(Node *mchain, const TypeOopPtr *t_oop, Node *load, PhaseGVN *phase) {
114 assert((t_oop != NULL), "sanity");
115 bool is_instance = t_oop->is_known_instance_field();
116 bool is_boxed_value_load = t_oop->is_ptr_to_boxed_value() &&
117 (load != NULL) && load->is_Load() &&
118 (phase->is_IterGVN() != NULL);
119 if (!(is_instance || is_boxed_value_load))
120 return mchain; // don't try to optimize non-instance types
121 uint instance_id = t_oop->instance_id();
122 Node *start_mem = phase->C->start()->proj_out(TypeFunc::Memory);
123 Node *prev = NULL;
124 Node *result = mchain;
125 while (prev != result) {
126 prev = result;
127 if (result == start_mem)
128 break; // hit one of our sentinels
129 // skip over a call which does not affect this memory slice
130 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {
131 Node *proj_in = result->in(0);
132 if (proj_in->is_Allocate() && proj_in->_idx == instance_id) {
133 break; // hit one of our sentinels
134 } else if (proj_in->is_Call()) {
135 CallNode *call = proj_in->as_Call();
136 if (!call->may_modify(t_oop, phase)) { // returns false for instances
137 result = call->in(TypeFunc::Memory);
138 }
139 } else if (proj_in->is_Initialize()) {
140 AllocateNode* alloc = proj_in->as_Initialize()->allocation();
141 // Stop if this is the initialization for the object instance which
142 // which contains this memory slice, otherwise skip over it.
143 if ((alloc == NULL) || (alloc->_idx == instance_id)) {
144 break;
145 }
146 if (is_instance) {
147 result = proj_in->in(TypeFunc::Memory);
148 } else if (is_boxed_value_load) {
149 Node* klass = alloc->in(AllocateNode::KlassNode);
150 const TypeKlassPtr* tklass = phase->type(klass)->is_klassptr();
151 if (tklass->klass_is_exact() && !tklass->klass()->equals(t_oop->klass())) {
152 result = proj_in->in(TypeFunc::Memory); // not related allocation
153 }
154 }
155 } else if (proj_in->is_MemBar()) {
156 result = proj_in->in(TypeFunc::Memory);
157 } else {
158 assert(false, "unexpected projection");
159 }
160 } else if (result->is_ClearArray()) {
161 if (!is_instance || !ClearArrayNode::step_through(&result, instance_id, phase)) {
162 // Can not bypass initialization of the instance
163 // we are looking for.
164 break;
165 }
166 // Otherwise skip it (the call updated 'result' value).
167 } else if (result->is_MergeMem()) {
168 result = step_through_mergemem(phase, result->as_MergeMem(), t_oop, NULL, tty);
169 }
170 }
171 return result;
172 }
173
174 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, Node *load, PhaseGVN *phase) {
175 const TypeOopPtr* t_oop = t_adr->isa_oopptr();
176 if (t_oop == NULL)
177 return mchain; // don't try to optimize non-oop types
178 Node* result = optimize_simple_memory_chain(mchain, t_oop, load, phase);
179 bool is_instance = t_oop->is_known_instance_field();
180 PhaseIterGVN *igvn = phase->is_IterGVN();
181 if (is_instance && igvn != NULL && result->is_Phi()) {
182 PhiNode *mphi = result->as_Phi();
183 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
184 const TypePtr *t = mphi->adr_type();
185 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
186 t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
187 t->is_oopptr()->cast_to_exactness(true)
188 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
189 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop) {
190 // clone the Phi with our address type
191 result = mphi->split_out_instance(t_adr, igvn);
192 } else {
193 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain");
194 }
195 }
196 return result;
197 }
198
199 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) {
200 uint alias_idx = phase->C->get_alias_index(tp);
201 Node *mem = mmem;
202 #ifdef ASSERT
203 {
204 // Check that current type is consistent with the alias index used during graph construction
205 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
206 bool consistent = adr_check == NULL || adr_check->empty() ||
207 phase->C->must_alias(adr_check, alias_idx );
208 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
209 if( !consistent && adr_check != NULL && !adr_check->empty() &&
210 tp->isa_aryptr() && tp->offset() == Type::OffsetBot &&
211 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot &&
212 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() ||
213 adr_check->offset() == oopDesc::klass_offset_in_bytes() ||
214 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) {
215 // don't assert if it is dead code.
216 consistent = true;
217 }
218 if( !consistent ) {
219 st->print("alias_idx==%d, adr_check==", alias_idx);
220 if( adr_check == NULL ) {
221 st->print("NULL");
222 } else {
223 adr_check->dump();
224 }
225 st->cr();
226 print_alias_types();
227 assert(consistent, "adr_check must match alias idx");
228 }
229 }
230 #endif
231 // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally
232 // means an array I have not precisely typed yet. Do not do any
233 // alias stuff with it any time soon.
234 const TypeOopPtr *toop = tp->isa_oopptr();
235 if( tp->base() != Type::AnyPtr &&
236 !(toop &&
237 toop->klass() != NULL &&
238 toop->klass()->is_java_lang_Object() &&
239 toop->offset() == Type::OffsetBot) ) {
240 // compress paths and change unreachable cycles to TOP
241 // If not, we can update the input infinitely along a MergeMem cycle
242 // Equivalent code in PhiNode::Ideal
243 Node* m = phase->transform(mmem);
244 // If transformed to a MergeMem, get the desired slice
245 // Otherwise the returned node represents memory for every slice
246 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
247 // Update input if it is progress over what we have now
248 }
249 return mem;
250 }
251
252 //--------------------------Ideal_common---------------------------------------
253 // Look for degenerate control and memory inputs. Bypass MergeMem inputs.
254 // Unhook non-raw memories from complete (macro-expanded) initializations.
255 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
256 // If our control input is a dead region, kill all below the region
257 Node *ctl = in(MemNode::Control);
258 if (ctl && remove_dead_region(phase, can_reshape))
259 return this;
260 ctl = in(MemNode::Control);
261 // Don't bother trying to transform a dead node
262 if (ctl && ctl->is_top()) return NodeSentinel;
263
264 PhaseIterGVN *igvn = phase->is_IterGVN();
265 // Wait if control on the worklist.
266 if (ctl && can_reshape && igvn != NULL) {
267 Node* bol = NULL;
268 Node* cmp = NULL;
269 if (ctl->in(0)->is_If()) {
270 assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity");
271 bol = ctl->in(0)->in(1);
272 if (bol->is_Bool())
273 cmp = ctl->in(0)->in(1)->in(1);
274 }
275 if (igvn->_worklist.member(ctl) ||
276 (bol != NULL && igvn->_worklist.member(bol)) ||
277 (cmp != NULL && igvn->_worklist.member(cmp)) ) {
278 // This control path may be dead.
279 // Delay this memory node transformation until the control is processed.
280 phase->is_IterGVN()->_worklist.push(this);
281 return NodeSentinel; // caller will return NULL
282 }
283 }
284 // Ignore if memory is dead, or self-loop
285 Node *mem = in(MemNode::Memory);
286 if (phase->type( mem ) == Type::TOP) return NodeSentinel; // caller will return NULL
287 assert(mem != this, "dead loop in MemNode::Ideal");
288
289 if (can_reshape && igvn != NULL && igvn->_worklist.member(mem)) {
290 // This memory slice may be dead.
291 // Delay this mem node transformation until the memory is processed.
292 phase->is_IterGVN()->_worklist.push(this);
293 return NodeSentinel; // caller will return NULL
294 }
295
296 Node *address = in(MemNode::Address);
297 const Type *t_adr = phase->type(address);
298 if (t_adr == Type::TOP) return NodeSentinel; // caller will return NULL
299
300 if (can_reshape && igvn != NULL &&
301 (igvn->_worklist.member(address) ||
302 igvn->_worklist.size() > 0 && (t_adr != adr_type())) ) {
303 // The address's base and type may change when the address is processed.
304 // Delay this mem node transformation until the address is processed.
305 phase->is_IterGVN()->_worklist.push(this);
306 return NodeSentinel; // caller will return NULL
307 }
308
309 // Do NOT remove or optimize the next lines: ensure a new alias index
310 // is allocated for an oop pointer type before Escape Analysis.
311 // Note: C++ will not remove it since the call has side effect.
312 if (t_adr->isa_oopptr()) {
313 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr());
314 }
315
316 Node* base = NULL;
317 if (address->is_AddP()) {
318 base = address->in(AddPNode::Base);
319 }
320 if (base != NULL && phase->type(base)->higher_equal(TypePtr::NULL_PTR) &&
321 !t_adr->isa_rawptr()) {
322 // Note: raw address has TOP base and top->higher_equal(TypePtr::NULL_PTR) is true.
323 // Skip this node optimization if its address has TOP base.
324 return NodeSentinel; // caller will return NULL
325 }
326
327 // Avoid independent memory operations
328 Node* old_mem = mem;
329
330 // The code which unhooks non-raw memories from complete (macro-expanded)
331 // initializations was removed. After macro-expansion all stores catched
332 // by Initialize node became raw stores and there is no information
333 // which memory slices they modify. So it is unsafe to move any memory
334 // operation above these stores. Also in most cases hooked non-raw memories
335 // were already unhooked by using information from detect_ptr_independence()
336 // and find_previous_store().
337
338 if (mem->is_MergeMem()) {
339 MergeMemNode* mmem = mem->as_MergeMem();
340 const TypePtr *tp = t_adr->is_ptr();
341
342 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
343 }
344
345 if (mem != old_mem) {
346 set_req(MemNode::Memory, mem);
347 if (can_reshape && old_mem->outcnt() == 0) {
348 igvn->_worklist.push(old_mem);
349 }
350 if (phase->type( mem ) == Type::TOP) return NodeSentinel;
351 return this;
352 }
353
354 // let the subclass continue analyzing...
355 return NULL;
356 }
357
358 // Helper function for proving some simple control dominations.
359 // Attempt to prove that all control inputs of 'dom' dominate 'sub'.
360 // Already assumes that 'dom' is available at 'sub', and that 'sub'
361 // is not a constant (dominated by the method's StartNode).
362 // Used by MemNode::find_previous_store to prove that the
363 // control input of a memory operation predates (dominates)
364 // an allocation it wants to look past.
365 bool MemNode::all_controls_dominate(Node* dom, Node* sub) {
366 if (dom == NULL || dom->is_top() || sub == NULL || sub->is_top())
367 return false; // Conservative answer for dead code
368
369 // Check 'dom'. Skip Proj and CatchProj nodes.
370 dom = dom->find_exact_control(dom);
371 if (dom == NULL || dom->is_top())
372 return false; // Conservative answer for dead code
373
374 if (dom == sub) {
375 // For the case when, for example, 'sub' is Initialize and the original
376 // 'dom' is Proj node of the 'sub'.
377 return false;
378 }
379
380 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub)
381 return true;
382
383 // 'dom' dominates 'sub' if its control edge and control edges
384 // of all its inputs dominate or equal to sub's control edge.
385
386 // Currently 'sub' is either Allocate, Initialize or Start nodes.
387 // Or Region for the check in LoadNode::Ideal();
388 // 'sub' should have sub->in(0) != NULL.
389 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() ||
390 sub->is_Region() || sub->is_Call(), "expecting only these nodes");
391
392 // Get control edge of 'sub'.
393 Node* orig_sub = sub;
394 sub = sub->find_exact_control(sub->in(0));
395 if (sub == NULL || sub->is_top())
396 return false; // Conservative answer for dead code
397
398 assert(sub->is_CFG(), "expecting control");
399
400 if (sub == dom)
401 return true;
402
403 if (sub->is_Start() || sub->is_Root())
404 return false;
405
406 {
407 // Check all control edges of 'dom'.
408
409 ResourceMark rm;
410 Arena* arena = Thread::current()->resource_area();
411 Node_List nlist(arena);
412 Unique_Node_List dom_list(arena);
413
414 dom_list.push(dom);
415 bool only_dominating_controls = false;
416
417 for (uint next = 0; next < dom_list.size(); next++) {
418 Node* n = dom_list.at(next);
419 if (n == orig_sub)
420 return false; // One of dom's inputs dominated by sub.
421 if (!n->is_CFG() && n->pinned()) {
422 // Check only own control edge for pinned non-control nodes.
423 n = n->find_exact_control(n->in(0));
424 if (n == NULL || n->is_top())
425 return false; // Conservative answer for dead code
426 assert(n->is_CFG(), "expecting control");
427 dom_list.push(n);
428 } else if (n->is_Con() || n->is_Start() || n->is_Root()) {
429 only_dominating_controls = true;
430 } else if (n->is_CFG()) {
431 if (n->dominates(sub, nlist))
432 only_dominating_controls = true;
433 else
434 return false;
435 } else {
436 // First, own control edge.
437 Node* m = n->find_exact_control(n->in(0));
438 if (m != NULL) {
439 if (m->is_top())
440 return false; // Conservative answer for dead code
441 dom_list.push(m);
442 }
443 // Now, the rest of edges.
444 uint cnt = n->req();
445 for (uint i = 1; i < cnt; i++) {
446 m = n->find_exact_control(n->in(i));
447 if (m == NULL || m->is_top())
448 continue;
449 dom_list.push(m);
450 }
451 }
452 }
453 return only_dominating_controls;
454 }
455 }
456
457 //---------------------detect_ptr_independence---------------------------------
458 // Used by MemNode::find_previous_store to prove that two base
459 // pointers are never equal.
460 // The pointers are accompanied by their associated allocations,
461 // if any, which have been previously discovered by the caller.
462 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
463 Node* p2, AllocateNode* a2,
464 PhaseTransform* phase) {
465 // Attempt to prove that these two pointers cannot be aliased.
466 // They may both manifestly be allocations, and they should differ.
467 // Or, if they are not both allocations, they can be distinct constants.
468 // Otherwise, one is an allocation and the other a pre-existing value.
469 if (a1 == NULL && a2 == NULL) { // neither an allocation
470 return (p1 != p2) && p1->is_Con() && p2->is_Con();
471 } else if (a1 != NULL && a2 != NULL) { // both allocations
472 return (a1 != a2);
473 } else if (a1 != NULL) { // one allocation a1
474 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.)
475 return all_controls_dominate(p2, a1);
476 } else { //(a2 != NULL) // one allocation a2
477 return all_controls_dominate(p1, a2);
478 }
479 return false;
480 }
481
482
483 // The logic for reordering loads and stores uses four steps:
484 // (a) Walk carefully past stores and initializations which we
485 // can prove are independent of this load.
486 // (b) Observe that the next memory state makes an exact match
487 // with self (load or store), and locate the relevant store.
488 // (c) Ensure that, if we were to wire self directly to the store,
489 // the optimizer would fold it up somehow.
490 // (d) Do the rewiring, and return, depending on some other part of
491 // the optimizer to fold up the load.
492 // This routine handles steps (a) and (b). Steps (c) and (d) are
493 // specific to loads and stores, so they are handled by the callers.
494 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.)
495 //
496 Node* MemNode::find_previous_store(PhaseTransform* phase) {
497 Node* ctrl = in(MemNode::Control);
498 Node* adr = in(MemNode::Address);
499 intptr_t offset = 0;
500 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
501 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase);
502
503 if (offset == Type::OffsetBot)
504 return NULL; // cannot unalias unless there are precise offsets
505
506 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr();
507
508 intptr_t size_in_bytes = memory_size();
509
510 Node* mem = in(MemNode::Memory); // start searching here...
511
512 int cnt = 50; // Cycle limiter
513 for (;;) { // While we can dance past unrelated stores...
514 if (--cnt < 0) break; // Caught in cycle or a complicated dance?
515
516 if (mem->is_Store()) {
517 Node* st_adr = mem->in(MemNode::Address);
518 intptr_t st_offset = 0;
519 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
520 if (st_base == NULL)
521 break; // inscrutable pointer
522 if (st_offset != offset && st_offset != Type::OffsetBot) {
523 const int MAX_STORE = BytesPerLong;
524 if (st_offset >= offset + size_in_bytes ||
525 st_offset <= offset - MAX_STORE ||
526 st_offset <= offset - mem->as_Store()->memory_size()) {
527 // Success: The offsets are provably independent.
528 // (You may ask, why not just test st_offset != offset and be done?
529 // The answer is that stores of different sizes can co-exist
530 // in the same sequence of RawMem effects. We sometimes initialize
531 // a whole 'tile' of array elements with a single jint or jlong.)
532 mem = mem->in(MemNode::Memory);
533 continue; // (a) advance through independent store memory
534 }
535 }
536 if (st_base != base &&
537 detect_ptr_independence(base, alloc,
538 st_base,
539 AllocateNode::Ideal_allocation(st_base, phase),
540 phase)) {
541 // Success: The bases are provably independent.
542 mem = mem->in(MemNode::Memory);
543 continue; // (a) advance through independent store memory
544 }
545
546 // (b) At this point, if the bases or offsets do not agree, we lose,
547 // since we have not managed to prove 'this' and 'mem' independent.
548 if (st_base == base && st_offset == offset) {
549 return mem; // let caller handle steps (c), (d)
550 }
551
552 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
553 InitializeNode* st_init = mem->in(0)->as_Initialize();
554 AllocateNode* st_alloc = st_init->allocation();
555 if (st_alloc == NULL)
556 break; // something degenerated
557 bool known_identical = false;
558 bool known_independent = false;
559 if (alloc == st_alloc)
560 known_identical = true;
561 else if (alloc != NULL)
562 known_independent = true;
563 else if (all_controls_dominate(this, st_alloc))
564 known_independent = true;
565
566 if (known_independent) {
567 // The bases are provably independent: Either they are
568 // manifestly distinct allocations, or else the control
569 // of this load dominates the store's allocation.
570 int alias_idx = phase->C->get_alias_index(adr_type());
571 if (alias_idx == Compile::AliasIdxRaw) {
572 mem = st_alloc->in(TypeFunc::Memory);
573 } else {
574 mem = st_init->memory(alias_idx);
575 }
576 continue; // (a) advance through independent store memory
577 }
578
579 // (b) at this point, if we are not looking at a store initializing
580 // the same allocation we are loading from, we lose.
581 if (known_identical) {
582 // From caller, can_see_stored_value will consult find_captured_store.
583 return mem; // let caller handle steps (c), (d)
584 }
585
586 } else if (addr_t != NULL && addr_t->is_known_instance_field()) {
587 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
588 if (mem->is_Proj() && mem->in(0)->is_Call()) {
589 CallNode *call = mem->in(0)->as_Call();
590 if (!call->may_modify(addr_t, phase)) {
591 mem = call->in(TypeFunc::Memory);
592 continue; // (a) advance through independent call memory
593 }
594 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) {
595 mem = mem->in(0)->in(TypeFunc::Memory);
596 continue; // (a) advance through independent MemBar memory
597 } else if (mem->is_ClearArray()) {
598 if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) {
599 // (the call updated 'mem' value)
600 continue; // (a) advance through independent allocation memory
601 } else {
602 // Can not bypass initialization of the instance
603 // we are looking for.
604 return mem;
605 }
606 } else if (mem->is_MergeMem()) {
607 int alias_idx = phase->C->get_alias_index(adr_type());
608 mem = mem->as_MergeMem()->memory_at(alias_idx);
609 continue; // (a) advance through independent MergeMem memory
610 }
611 }
612
613 // Unless there is an explicit 'continue', we must bail out here,
614 // because 'mem' is an inscrutable memory state (e.g., a call).
615 break;
616 }
617
618 return NULL; // bail out
619 }
620
621 //----------------------calculate_adr_type-------------------------------------
622 // Helper function. Notices when the given type of address hits top or bottom.
623 // Also, asserts a cross-check of the type against the expected address type.
624 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
625 if (t == Type::TOP) return NULL; // does not touch memory any more?
626 #ifdef PRODUCT
627 cross_check = NULL;
628 #else
629 if (!VerifyAliases || is_error_reported() || Node::in_dump()) cross_check = NULL;
630 #endif
631 const TypePtr* tp = t->isa_ptr();
632 if (tp == NULL) {
633 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
634 return TypePtr::BOTTOM; // touches lots of memory
635 } else {
636 #ifdef ASSERT
637 // %%%% [phh] We don't check the alias index if cross_check is
638 // TypeRawPtr::BOTTOM. Needs to be investigated.
639 if (cross_check != NULL &&
640 cross_check != TypePtr::BOTTOM &&
641 cross_check != TypeRawPtr::BOTTOM) {
642 // Recheck the alias index, to see if it has changed (due to a bug).
643 Compile* C = Compile::current();
644 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
645 "must stay in the original alias category");
646 // The type of the address must be contained in the adr_type,
647 // disregarding "null"-ness.
648 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
649 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
650 assert(cross_check->meet(tp_notnull) == cross_check->remove_speculative(),
651 "real address must not escape from expected memory type");
652 }
653 #endif
654 return tp;
655 }
656 }
657
658 //------------------------adr_phi_is_loop_invariant----------------------------
659 // A helper function for Ideal_DU_postCCP to check if a Phi in a counted
660 // loop is loop invariant. Make a quick traversal of Phi and associated
661 // CastPP nodes, looking to see if they are a closed group within the loop.
662 bool MemNode::adr_phi_is_loop_invariant(Node* adr_phi, Node* cast) {
663 // The idea is that the phi-nest must boil down to only CastPP nodes
664 // with the same data. This implies that any path into the loop already
665 // includes such a CastPP, and so the original cast, whatever its input,
666 // must be covered by an equivalent cast, with an earlier control input.
667 ResourceMark rm;
668
669 // The loop entry input of the phi should be the unique dominating
670 // node for every Phi/CastPP in the loop.
671 Unique_Node_List closure;
672 closure.push(adr_phi->in(LoopNode::EntryControl));
673
674 // Add the phi node and the cast to the worklist.
675 Unique_Node_List worklist;
676 worklist.push(adr_phi);
677 if( cast != NULL ){
678 if( !cast->is_ConstraintCast() ) return false;
679 worklist.push(cast);
680 }
681
682 // Begin recursive walk of phi nodes.
683 while( worklist.size() ){
684 // Take a node off the worklist
685 Node *n = worklist.pop();
686 if( !closure.member(n) ){
687 // Add it to the closure.
688 closure.push(n);
689 // Make a sanity check to ensure we don't waste too much time here.
690 if( closure.size() > 20) return false;
691 // This node is OK if:
692 // - it is a cast of an identical value
693 // - or it is a phi node (then we add its inputs to the worklist)
694 // Otherwise, the node is not OK, and we presume the cast is not invariant
695 if( n->is_ConstraintCast() ){
696 worklist.push(n->in(1));
697 } else if( n->is_Phi() ) {
698 for( uint i = 1; i < n->req(); i++ ) {
699 worklist.push(n->in(i));
700 }
701 } else {
702 return false;
703 }
704 }
705 }
706
707 // Quit when the worklist is empty, and we've found no offending nodes.
708 return true;
709 }
710
711 //------------------------------Ideal_DU_postCCP-------------------------------
712 // Find any cast-away of null-ness and keep its control. Null cast-aways are
713 // going away in this pass and we need to make this memory op depend on the
714 // gating null check.
715 Node *MemNode::Ideal_DU_postCCP( PhaseCCP *ccp ) {
716 return Ideal_common_DU_postCCP(ccp, this, in(MemNode::Address));
717 }
718
719 // I tried to leave the CastPP's in. This makes the graph more accurate in
720 // some sense; we get to keep around the knowledge that an oop is not-null
721 // after some test. Alas, the CastPP's interfere with GVN (some values are
722 // the regular oop, some are the CastPP of the oop, all merge at Phi's which
723 // cannot collapse, etc). This cost us 10% on SpecJVM, even when I removed
724 // some of the more trivial cases in the optimizer. Removing more useless
725 // Phi's started allowing Loads to illegally float above null checks. I gave
726 // up on this approach. CNC 10/20/2000
727 // This static method may be called not from MemNode (EncodePNode calls it).
728 // Only the control edge of the node 'n' might be updated.
729 Node *MemNode::Ideal_common_DU_postCCP( PhaseCCP *ccp, Node* n, Node* adr ) {
730 Node *skipped_cast = NULL;
731 // Need a null check? Regular static accesses do not because they are
732 // from constant addresses. Array ops are gated by the range check (which
733 // always includes a NULL check). Just check field ops.
734 if( n->in(MemNode::Control) == NULL ) {
735 // Scan upwards for the highest location we can place this memory op.
736 while( true ) {
737 switch( adr->Opcode() ) {
738
739 case Op_AddP: // No change to NULL-ness, so peek thru AddP's
740 adr = adr->in(AddPNode::Base);
741 continue;
742
743 case Op_DecodeN: // No change to NULL-ness, so peek thru
744 case Op_DecodeNKlass:
745 adr = adr->in(1);
746 continue;
747
748 case Op_EncodeP:
749 case Op_EncodePKlass:
750 // EncodeP node's control edge could be set by this method
751 // when EncodeP node depends on CastPP node.
752 //
753 // Use its control edge for memory op because EncodeP may go away
754 // later when it is folded with following or preceding DecodeN node.
755 if (adr->in(0) == NULL) {
756 // Keep looking for cast nodes.
757 adr = adr->in(1);
758 continue;
759 }
760 ccp->hash_delete(n);
761 n->set_req(MemNode::Control, adr->in(0));
762 ccp->hash_insert(n);
763 return n;
764
765 case Op_CastPP:
766 // If the CastPP is useless, just peek on through it.
767 if( ccp->type(adr) == ccp->type(adr->in(1)) ) {
768 // Remember the cast that we've peeked though. If we peek
769 // through more than one, then we end up remembering the highest
770 // one, that is, if in a loop, the one closest to the top.
771 skipped_cast = adr;
772 adr = adr->in(1);
773 continue;
774 }
775 // CastPP is going away in this pass! We need this memory op to be
776 // control-dependent on the test that is guarding the CastPP.
777 ccp->hash_delete(n);
778 n->set_req(MemNode::Control, adr->in(0));
779 ccp->hash_insert(n);
780 return n;
781
782 case Op_Phi:
783 // Attempt to float above a Phi to some dominating point.
784 if (adr->in(0) != NULL && adr->in(0)->is_CountedLoop()) {
785 // If we've already peeked through a Cast (which could have set the
786 // control), we can't float above a Phi, because the skipped Cast
787 // may not be loop invariant.
788 if (adr_phi_is_loop_invariant(adr, skipped_cast)) {
789 adr = adr->in(1);
790 continue;
791 }
792 }
793
794 // Intentional fallthrough!
795
796 // No obvious dominating point. The mem op is pinned below the Phi
797 // by the Phi itself. If the Phi goes away (no true value is merged)
798 // then the mem op can float, but not indefinitely. It must be pinned
799 // behind the controls leading to the Phi.
800 case Op_CheckCastPP:
801 // These usually stick around to change address type, however a
802 // useless one can be elided and we still need to pick up a control edge
803 if (adr->in(0) == NULL) {
804 // This CheckCastPP node has NO control and is likely useless. But we
805 // need check further up the ancestor chain for a control input to keep
806 // the node in place. 4959717.
807 skipped_cast = adr;
808 adr = adr->in(1);
809 continue;
810 }
811 ccp->hash_delete(n);
812 n->set_req(MemNode::Control, adr->in(0));
813 ccp->hash_insert(n);
814 return n;
815
816 // List of "safe" opcodes; those that implicitly block the memory
817 // op below any null check.
818 case Op_CastX2P: // no null checks on native pointers
819 case Op_Parm: // 'this' pointer is not null
820 case Op_LoadP: // Loading from within a klass
821 case Op_LoadN: // Loading from within a klass
822 case Op_LoadKlass: // Loading from within a klass
823 case Op_LoadNKlass: // Loading from within a klass
824 case Op_ConP: // Loading from a klass
825 case Op_ConN: // Loading from a klass
826 case Op_ConNKlass: // Loading from a klass
827 case Op_CreateEx: // Sucking up the guts of an exception oop
828 case Op_Con: // Reading from TLS
829 case Op_CMoveP: // CMoveP is pinned
830 case Op_CMoveN: // CMoveN is pinned
831 break; // No progress
832
833 case Op_Proj: // Direct call to an allocation routine
834 case Op_SCMemProj: // Memory state from store conditional ops
835 #ifdef ASSERT
836 {
837 assert(adr->as_Proj()->_con == TypeFunc::Parms, "must be return value");
838 const Node* call = adr->in(0);
839 if (call->is_CallJava()) {
840 const CallJavaNode* call_java = call->as_CallJava();
841 const TypeTuple *r = call_java->tf()->range();
842 assert(r->cnt() > TypeFunc::Parms, "must return value");
843 const Type* ret_type = r->field_at(TypeFunc::Parms);
844 assert(ret_type && ret_type->isa_ptr(), "must return pointer");
845 // We further presume that this is one of
846 // new_instance_Java, new_array_Java, or
847 // the like, but do not assert for this.
848 } else if (call->is_Allocate()) {
849 // similar case to new_instance_Java, etc.
850 } else if (!call->is_CallLeaf()) {
851 // Projections from fetch_oop (OSR) are allowed as well.
852 ShouldNotReachHere();
853 }
854 }
855 #endif
856 break;
857 default:
858 ShouldNotReachHere();
859 }
860 break;
861 }
862 }
863
864 return NULL; // No progress
865 }
866
867
868 //=============================================================================
869 // Should LoadNode::Ideal() attempt to remove control edges?
870 bool LoadNode::can_remove_control() const {
871 return true;
872 }
873 uint LoadNode::size_of() const { return sizeof(*this); }
874 uint LoadNode::cmp( const Node &n ) const
875 { return !Type::cmp( _type, ((LoadNode&)n)._type ); }
876 const Type *LoadNode::bottom_type() const { return _type; }
877 uint LoadNode::ideal_reg() const {
878 return _type->ideal_reg();
879 }
880
881 #ifndef PRODUCT
882 void LoadNode::dump_spec(outputStream *st) const {
883 MemNode::dump_spec(st);
884 if( !Verbose && !WizardMode ) {
885 // standard dump does this in Verbose and WizardMode
886 st->print(" #"); _type->dump_on(st);
887 }
888 if (!_depends_only_on_test) {
889 st->print(" (does not depend only on test)");
890 }
891 }
892 #endif
893
894 #ifdef ASSERT
895 //----------------------------is_immutable_value-------------------------------
896 // Helper function to allow a raw load without control edge for some cases
897 bool LoadNode::is_immutable_value(Node* adr) {
898 return (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() &&
899 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal &&
900 (adr->in(AddPNode::Offset)->find_intptr_t_con(-1) ==
901 in_bytes(JavaThread::osthread_offset())));
902 }
903 #endif
904
905 //----------------------------LoadNode::make-----------------------------------
906 // Polymorphic factory method:
907 Node *LoadNode::make(PhaseGVN& gvn, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt, MemOrd mo, ControlDependency control_dependency) {
908 Compile* C = gvn.C;
909
910 // sanity check the alias category against the created node type
911 assert(!(adr_type->isa_oopptr() &&
912 adr_type->offset() == oopDesc::klass_offset_in_bytes()),
913 "use LoadKlassNode instead");
914 assert(!(adr_type->isa_aryptr() &&
915 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
916 "use LoadRangeNode instead");
917 // Check control edge of raw loads
918 assert( ctl != NULL || C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
919 // oop will be recorded in oop map if load crosses safepoint
920 rt->isa_oopptr() || is_immutable_value(adr),
921 "raw memory operations should have control edge");
922 switch (bt) {
923 case T_BOOLEAN: return new (C) LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency);
924 case T_BYTE: return new (C) LoadBNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency);
925 case T_INT: return new (C) LoadINode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency);
926 case T_CHAR: return new (C) LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency);
927 case T_SHORT: return new (C) LoadSNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency);
928 case T_LONG: return new (C) LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency);
929 case T_FLOAT: return new (C) LoadFNode (ctl, mem, adr, adr_type, rt, mo, control_dependency);
930 case T_DOUBLE: return new (C) LoadDNode (ctl, mem, adr, adr_type, rt, mo, control_dependency);
931 case T_ADDRESS: return new (C) LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency);
932 case T_OBJECT:
933 #ifdef _LP64
934 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
935 Node* load = gvn.transform(new (C) LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo, control_dependency));
936 return new (C) DecodeNNode(load, load->bottom_type()->make_ptr());
937 } else
938 #endif
939 {
940 assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop");
941 return new (C) LoadPNode(ctl, mem, adr, adr_type, rt->is_oopptr(), mo, control_dependency);
942 }
943 }
944 ShouldNotReachHere();
945 return (LoadNode*)NULL;
946 }
947
948 LoadLNode* LoadLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo, ControlDependency control_dependency) {
949 bool require_atomic = true;
950 return new (C) LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency, require_atomic);
951 }
952
953 LoadDNode* LoadDNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo, ControlDependency control_dependency) {
954 bool require_atomic = true;
955 return new (C) LoadDNode(ctl, mem, adr, adr_type, rt, mo, control_dependency, require_atomic);
956 }
957
958
959
960 //------------------------------hash-------------------------------------------
961 uint LoadNode::hash() const {
962 // unroll addition of interesting fields
963 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
964 }
965
966 static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) {
967 if ((atp != NULL) && (atp->index() >= Compile::AliasIdxRaw)) {
968 bool non_volatile = (atp->field() != NULL) && !atp->field()->is_volatile();
969 bool is_stable_ary = FoldStableValues &&
970 (tp != NULL) && (tp->isa_aryptr() != NULL) &&
971 tp->isa_aryptr()->is_stable();
972
973 return (eliminate_boxing && non_volatile) || is_stable_ary;
974 }
975
976 return false;
977 }
978
979 //---------------------------can_see_stored_value------------------------------
980 // This routine exists to make sure this set of tests is done the same
981 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
982 // will change the graph shape in a way which makes memory alive twice at the
983 // same time (uses the Oracle model of aliasing), then some
984 // LoadXNode::Identity will fold things back to the equivalence-class model
985 // of aliasing.
986 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const {
987 Node* ld_adr = in(MemNode::Address);
988 intptr_t ld_off = 0;
989 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
990 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
991 Compile::AliasType* atp = (tp != NULL) ? phase->C->alias_type(tp) : NULL;
992 // This is more general than load from boxing objects.
993 if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) {
994 uint alias_idx = atp->index();
995 bool final = !atp->is_rewritable();
996 Node* result = NULL;
997 Node* current = st;
998 // Skip through chains of MemBarNodes checking the MergeMems for
999 // new states for the slice of this load. Stop once any other
1000 // kind of node is encountered. Loads from final memory can skip
1001 // through any kind of MemBar but normal loads shouldn't skip
1002 // through MemBarAcquire since the could allow them to move out of
1003 // a synchronized region.
1004 while (current->is_Proj()) {
1005 int opc = current->in(0)->Opcode();
1006 if ((final && (opc == Op_MemBarAcquire ||
1007 opc == Op_MemBarAcquireLock ||
1008 opc == Op_LoadFence)) ||
1009 opc == Op_MemBarRelease ||
1010 opc == Op_StoreFence ||
1011 opc == Op_MemBarReleaseLock ||
1012 opc == Op_MemBarCPUOrder) {
1013 Node* mem = current->in(0)->in(TypeFunc::Memory);
1014 if (mem->is_MergeMem()) {
1015 MergeMemNode* merge = mem->as_MergeMem();
1016 Node* new_st = merge->memory_at(alias_idx);
1017 if (new_st == merge->base_memory()) {
1018 // Keep searching
1019 current = new_st;
1020 continue;
1021 }
1022 // Save the new memory state for the slice and fall through
1023 // to exit.
1024 result = new_st;
1025 }
1026 }
1027 break;
1028 }
1029 if (result != NULL) {
1030 st = result;
1031 }
1032 }
1033
1034 // Loop around twice in the case Load -> Initialize -> Store.
1035 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
1036 for (int trip = 0; trip <= 1; trip++) {
1037
1038 if (st->is_Store()) {
1039 Node* st_adr = st->in(MemNode::Address);
1040 if (!phase->eqv(st_adr, ld_adr)) {
1041 // Try harder before giving up... Match raw and non-raw pointers.
1042 intptr_t st_off = 0;
1043 AllocateNode* alloc = AllocateNode::Ideal_allocation(st_adr, phase, st_off);
1044 if (alloc == NULL) return NULL;
1045 if (alloc != ld_alloc) return NULL;
1046 if (ld_off != st_off) return NULL;
1047 // At this point we have proven something like this setup:
1048 // A = Allocate(...)
1049 // L = LoadQ(, AddP(CastPP(, A.Parm),, #Off))
1050 // S = StoreQ(, AddP(, A.Parm , #Off), V)
1051 // (Actually, we haven't yet proven the Q's are the same.)
1052 // In other words, we are loading from a casted version of
1053 // the same pointer-and-offset that we stored to.
1054 // Thus, we are able to replace L by V.
1055 }
1056 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
1057 if (store_Opcode() != st->Opcode())
1058 return NULL;
1059 return st->in(MemNode::ValueIn);
1060 }
1061
1062 // A load from a freshly-created object always returns zero.
1063 // (This can happen after LoadNode::Ideal resets the load's memory input
1064 // to find_captured_store, which returned InitializeNode::zero_memory.)
1065 if (st->is_Proj() && st->in(0)->is_Allocate() &&
1066 (st->in(0) == ld_alloc) &&
1067 (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) {
1068 // return a zero value for the load's basic type
1069 // (This is one of the few places where a generic PhaseTransform
1070 // can create new nodes. Think of it as lazily manifesting
1071 // virtually pre-existing constants.)
1072 return phase->zerocon(memory_type());
1073 }
1074
1075 // A load from an initialization barrier can match a captured store.
1076 if (st->is_Proj() && st->in(0)->is_Initialize()) {
1077 InitializeNode* init = st->in(0)->as_Initialize();
1078 AllocateNode* alloc = init->allocation();
1079 if ((alloc != NULL) && (alloc == ld_alloc)) {
1080 // examine a captured store value
1081 st = init->find_captured_store(ld_off, memory_size(), phase);
1082 if (st != NULL)
1083 continue; // take one more trip around
1084 }
1085 }
1086
1087 // Load boxed value from result of valueOf() call is input parameter.
1088 if (this->is_Load() && ld_adr->is_AddP() &&
1089 (tp != NULL) && tp->is_ptr_to_boxed_value()) {
1090 intptr_t ignore = 0;
1091 Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore);
1092 if (base != NULL && base->is_Proj() &&
1093 base->as_Proj()->_con == TypeFunc::Parms &&
1094 base->in(0)->is_CallStaticJava() &&
1095 base->in(0)->as_CallStaticJava()->is_boxing_method()) {
1096 return base->in(0)->in(TypeFunc::Parms);
1097 }
1098 }
1099
1100 break;
1101 }
1102
1103 return NULL;
1104 }
1105
1106 //----------------------is_instance_field_load_with_local_phi------------------
1107 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
1108 if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl &&
1109 in(Address)->is_AddP() ) {
1110 const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr();
1111 // Only instances and boxed values.
1112 if( t_oop != NULL &&
1113 (t_oop->is_ptr_to_boxed_value() ||
1114 t_oop->is_known_instance_field()) &&
1115 t_oop->offset() != Type::OffsetBot &&
1116 t_oop->offset() != Type::OffsetTop) {
1117 return true;
1118 }
1119 }
1120 return false;
1121 }
1122
1123 //------------------------------Identity---------------------------------------
1124 // Loads are identity if previous store is to same address
1125 Node *LoadNode::Identity( PhaseTransform *phase ) {
1126 // If the previous store-maker is the right kind of Store, and the store is
1127 // to the same address, then we are equal to the value stored.
1128 Node* mem = in(Memory);
1129 Node* value = can_see_stored_value(mem, phase);
1130 if( value ) {
1131 // byte, short & char stores truncate naturally.
1132 // A load has to load the truncated value which requires
1133 // some sort of masking operation and that requires an
1134 // Ideal call instead of an Identity call.
1135 if (memory_size() < BytesPerInt) {
1136 // If the input to the store does not fit with the load's result type,
1137 // it must be truncated via an Ideal call.
1138 if (!phase->type(value)->higher_equal(phase->type(this)))
1139 return this;
1140 }
1141 // (This works even when value is a Con, but LoadNode::Value
1142 // usually runs first, producing the singleton type of the Con.)
1143 return value;
1144 }
1145
1146 // Search for an existing data phi which was generated before for the same
1147 // instance's field to avoid infinite generation of phis in a loop.
1148 Node *region = mem->in(0);
1149 if (is_instance_field_load_with_local_phi(region)) {
1150 const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr();
1151 int this_index = phase->C->get_alias_index(addr_t);
1152 int this_offset = addr_t->offset();
1153 int this_iid = addr_t->instance_id();
1154 if (!addr_t->is_known_instance() &&
1155 addr_t->is_ptr_to_boxed_value()) {
1156 // Use _idx of address base (could be Phi node) for boxed values.
1157 intptr_t ignore = 0;
1158 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1159 this_iid = base->_idx;
1160 }
1161 const Type* this_type = bottom_type();
1162 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1163 Node* phi = region->fast_out(i);
1164 if (phi->is_Phi() && phi != mem &&
1165 phi->as_Phi()->is_same_inst_field(this_type, this_iid, this_index, this_offset)) {
1166 return phi;
1167 }
1168 }
1169 }
1170
1171 return this;
1172 }
1173
1174 // We're loading from an object which has autobox behaviour.
1175 // If this object is result of a valueOf call we'll have a phi
1176 // merging a newly allocated object and a load from the cache.
1177 // We want to replace this load with the original incoming
1178 // argument to the valueOf call.
1179 Node* LoadNode::eliminate_autobox(PhaseGVN* phase) {
1180 assert(phase->C->eliminate_boxing(), "sanity");
1181 intptr_t ignore = 0;
1182 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1183 if ((base == NULL) || base->is_Phi()) {
1184 // Push the loads from the phi that comes from valueOf up
1185 // through it to allow elimination of the loads and the recovery
1186 // of the original value. It is done in split_through_phi().
1187 return NULL;
1188 } else if (base->is_Load() ||
1189 base->is_DecodeN() && base->in(1)->is_Load()) {
1190 // Eliminate the load of boxed value for integer types from the cache
1191 // array by deriving the value from the index into the array.
1192 // Capture the offset of the load and then reverse the computation.
1193
1194 // Get LoadN node which loads a boxing object from 'cache' array.
1195 if (base->is_DecodeN()) {
1196 base = base->in(1);
1197 }
1198 if (!base->in(Address)->is_AddP()) {
1199 return NULL; // Complex address
1200 }
1201 AddPNode* address = base->in(Address)->as_AddP();
1202 Node* cache_base = address->in(AddPNode::Base);
1203 if ((cache_base != NULL) && cache_base->is_DecodeN()) {
1204 // Get ConP node which is static 'cache' field.
1205 cache_base = cache_base->in(1);
1206 }
1207 if ((cache_base != NULL) && cache_base->is_Con()) {
1208 const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr();
1209 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1210 Node* elements[4];
1211 int shift = exact_log2(type2aelembytes(T_OBJECT));
1212 int count = address->unpack_offsets(elements, ARRAY_SIZE(elements));
1213 if ((count > 0) && elements[0]->is_Con() &&
1214 ((count == 1) ||
1215 (count == 2) && elements[1]->Opcode() == Op_LShiftX &&
1216 elements[1]->in(2) == phase->intcon(shift))) {
1217 ciObjArray* array = base_type->const_oop()->as_obj_array();
1218 // Fetch the box object cache[0] at the base of the array and get its value
1219 ciInstance* box = array->obj_at(0)->as_instance();
1220 ciInstanceKlass* ik = box->klass()->as_instance_klass();
1221 assert(ik->is_box_klass(), "sanity");
1222 assert(ik->nof_nonstatic_fields() == 1, "change following code");
1223 if (ik->nof_nonstatic_fields() == 1) {
1224 // This should be true nonstatic_field_at requires calling
1225 // nof_nonstatic_fields so check it anyway
1226 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1227 BasicType bt = c.basic_type();
1228 // Only integer types have boxing cache.
1229 assert(bt == T_BOOLEAN || bt == T_CHAR ||
1230 bt == T_BYTE || bt == T_SHORT ||
1231 bt == T_INT || bt == T_LONG, err_msg_res("wrong type = %s", type2name(bt)));
1232 jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int();
1233 if (cache_low != (int)cache_low) {
1234 return NULL; // should not happen since cache is array indexed by value
1235 }
1236 jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift);
1237 if (offset != (int)offset) {
1238 return NULL; // should not happen since cache is array indexed by value
1239 }
1240 // Add up all the offsets making of the address of the load
1241 Node* result = elements[0];
1242 for (int i = 1; i < count; i++) {
1243 result = phase->transform(new (phase->C) AddXNode(result, elements[i]));
1244 }
1245 // Remove the constant offset from the address and then
1246 result = phase->transform(new (phase->C) AddXNode(result, phase->MakeConX(-(int)offset)));
1247 // remove the scaling of the offset to recover the original index.
1248 if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) {
1249 // Peel the shift off directly but wrap it in a dummy node
1250 // since Ideal can't return existing nodes
1251 result = new (phase->C) RShiftXNode(result->in(1), phase->intcon(0));
1252 } else if (result->is_Add() && result->in(2)->is_Con() &&
1253 result->in(1)->Opcode() == Op_LShiftX &&
1254 result->in(1)->in(2) == phase->intcon(shift)) {
1255 // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z)
1256 // but for boxing cache access we know that X<<Z will not overflow
1257 // (there is range check) so we do this optimizatrion by hand here.
1258 Node* add_con = new (phase->C) RShiftXNode(result->in(2), phase->intcon(shift));
1259 result = new (phase->C) AddXNode(result->in(1)->in(1), phase->transform(add_con));
1260 } else {
1261 result = new (phase->C) RShiftXNode(result, phase->intcon(shift));
1262 }
1263 #ifdef _LP64
1264 if (bt != T_LONG) {
1265 result = new (phase->C) ConvL2INode(phase->transform(result));
1266 }
1267 #else
1268 if (bt == T_LONG) {
1269 result = new (phase->C) ConvI2LNode(phase->transform(result));
1270 }
1271 #endif
1272 // Boxing/unboxing can be done from signed & unsigned loads (e.g. LoadUB -> ... -> LoadB pair).
1273 // Need to preserve unboxing load type if it is unsigned.
1274 switch(this->Opcode()) {
1275 case Op_LoadUB:
1276 result = new (phase->C) AndINode(phase->transform(result), phase->intcon(0xFF));
1277 break;
1278 case Op_LoadUS:
1279 result = new (phase->C) AndINode(phase->transform(result), phase->intcon(0xFFFF));
1280 break;
1281 }
1282 return result;
1283 }
1284 }
1285 }
1286 }
1287 }
1288 return NULL;
1289 }
1290
1291 static bool stable_phi(PhiNode* phi, PhaseGVN *phase) {
1292 Node* region = phi->in(0);
1293 if (region == NULL) {
1294 return false; // Wait stable graph
1295 }
1296 uint cnt = phi->req();
1297 for (uint i = 1; i < cnt; i++) {
1298 Node* rc = region->in(i);
1299 if (rc == NULL || phase->type(rc) == Type::TOP)
1300 return false; // Wait stable graph
1301 Node* in = phi->in(i);
1302 if (in == NULL || phase->type(in) == Type::TOP)
1303 return false; // Wait stable graph
1304 }
1305 return true;
1306 }
1307 //------------------------------split_through_phi------------------------------
1308 // Split instance or boxed field load through Phi.
1309 Node *LoadNode::split_through_phi(PhaseGVN *phase) {
1310 Node* mem = in(Memory);
1311 Node* address = in(Address);
1312 const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr();
1313
1314 assert((t_oop != NULL) &&
1315 (t_oop->is_known_instance_field() ||
1316 t_oop->is_ptr_to_boxed_value()), "invalide conditions");
1317
1318 Compile* C = phase->C;
1319 intptr_t ignore = 0;
1320 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1321 bool base_is_phi = (base != NULL) && base->is_Phi();
1322 bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() &&
1323 (base != NULL) && (base == address->in(AddPNode::Base)) &&
1324 phase->type(base)->higher_equal(TypePtr::NOTNULL);
1325
1326 if (!((mem->is_Phi() || base_is_phi) &&
1327 (load_boxed_values || t_oop->is_known_instance_field()))) {
1328 return NULL; // memory is not Phi
1329 }
1330
1331 if (mem->is_Phi()) {
1332 if (!stable_phi(mem->as_Phi(), phase)) {
1333 return NULL; // Wait stable graph
1334 }
1335 uint cnt = mem->req();
1336 // Check for loop invariant memory.
1337 if (cnt == 3) {
1338 for (uint i = 1; i < cnt; i++) {
1339 Node* in = mem->in(i);
1340 Node* m = optimize_memory_chain(in, t_oop, this, phase);
1341 if (m == mem) {
1342 set_req(Memory, mem->in(cnt - i));
1343 return this; // made change
1344 }
1345 }
1346 }
1347 }
1348 if (base_is_phi) {
1349 if (!stable_phi(base->as_Phi(), phase)) {
1350 return NULL; // Wait stable graph
1351 }
1352 uint cnt = base->req();
1353 // Check for loop invariant memory.
1354 if (cnt == 3) {
1355 for (uint i = 1; i < cnt; i++) {
1356 if (base->in(i) == base) {
1357 return NULL; // Wait stable graph
1358 }
1359 }
1360 }
1361 }
1362
1363 bool load_boxed_phi = load_boxed_values && base_is_phi && (base->in(0) == mem->in(0));
1364
1365 // Split through Phi (see original code in loopopts.cpp).
1366 assert(C->have_alias_type(t_oop), "instance should have alias type");
1367
1368 // Do nothing here if Identity will find a value
1369 // (to avoid infinite chain of value phis generation).
1370 if (!phase->eqv(this, this->Identity(phase)))
1371 return NULL;
1372
1373 // Select Region to split through.
1374 Node* region;
1375 if (!base_is_phi) {
1376 assert(mem->is_Phi(), "sanity");
1377 region = mem->in(0);
1378 // Skip if the region dominates some control edge of the address.
1379 if (!MemNode::all_controls_dominate(address, region))
1380 return NULL;
1381 } else if (!mem->is_Phi()) {
1382 assert(base_is_phi, "sanity");
1383 region = base->in(0);
1384 // Skip if the region dominates some control edge of the memory.
1385 if (!MemNode::all_controls_dominate(mem, region))
1386 return NULL;
1387 } else if (base->in(0) != mem->in(0)) {
1388 assert(base_is_phi && mem->is_Phi(), "sanity");
1389 if (MemNode::all_controls_dominate(mem, base->in(0))) {
1390 region = base->in(0);
1391 } else if (MemNode::all_controls_dominate(address, mem->in(0))) {
1392 region = mem->in(0);
1393 } else {
1394 return NULL; // complex graph
1395 }
1396 } else {
1397 assert(base->in(0) == mem->in(0), "sanity");
1398 region = mem->in(0);
1399 }
1400
1401 const Type* this_type = this->bottom_type();
1402 int this_index = C->get_alias_index(t_oop);
1403 int this_offset = t_oop->offset();
1404 int this_iid = t_oop->instance_id();
1405 if (!t_oop->is_known_instance() && load_boxed_values) {
1406 // Use _idx of address base for boxed values.
1407 this_iid = base->_idx;
1408 }
1409 PhaseIterGVN* igvn = phase->is_IterGVN();
1410 Node* phi = new (C) PhiNode(region, this_type, NULL, this_iid, this_index, this_offset);
1411 for (uint i = 1; i < region->req(); i++) {
1412 Node* x;
1413 Node* the_clone = NULL;
1414 if (region->in(i) == C->top()) {
1415 x = C->top(); // Dead path? Use a dead data op
1416 } else {
1417 x = this->clone(); // Else clone up the data op
1418 the_clone = x; // Remember for possible deletion.
1419 // Alter data node to use pre-phi inputs
1420 if (this->in(0) == region) {
1421 x->set_req(0, region->in(i));
1422 } else {
1423 x->set_req(0, NULL);
1424 }
1425 if (mem->is_Phi() && (mem->in(0) == region)) {
1426 x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone.
1427 }
1428 if (address->is_Phi() && address->in(0) == region) {
1429 x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone
1430 }
1431 if (base_is_phi && (base->in(0) == region)) {
1432 Node* base_x = base->in(i); // Clone address for loads from boxed objects.
1433 Node* adr_x = phase->transform(new (C) AddPNode(base_x,base_x,address->in(AddPNode::Offset)));
1434 x->set_req(Address, adr_x);
1435 }
1436 }
1437 // Check for a 'win' on some paths
1438 const Type *t = x->Value(igvn);
1439
1440 bool singleton = t->singleton();
1441
1442 // See comments in PhaseIdealLoop::split_thru_phi().
1443 if (singleton && t == Type::TOP) {
1444 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1445 }
1446
1447 if (singleton) {
1448 x = igvn->makecon(t);
1449 } else {
1450 // We now call Identity to try to simplify the cloned node.
1451 // Note that some Identity methods call phase->type(this).
1452 // Make sure that the type array is big enough for
1453 // our new node, even though we may throw the node away.
1454 // (This tweaking with igvn only works because x is a new node.)
1455 igvn->set_type(x, t);
1456 // If x is a TypeNode, capture any more-precise type permanently into Node
1457 // otherwise it will be not updated during igvn->transform since
1458 // igvn->type(x) is set to x->Value() already.
1459 x->raise_bottom_type(t);
1460 Node *y = x->Identity(igvn);
1461 if (y != x) {
1462 x = y;
1463 } else {
1464 y = igvn->hash_find_insert(x);
1465 if (y) {
1466 x = y;
1467 } else {
1468 // Else x is a new node we are keeping
1469 // We do not need register_new_node_with_optimizer
1470 // because set_type has already been called.
1471 igvn->_worklist.push(x);
1472 }
1473 }
1474 }
1475 if (x != the_clone && the_clone != NULL) {
1476 igvn->remove_dead_node(the_clone);
1477 }
1478 phi->set_req(i, x);
1479 }
1480 // Record Phi
1481 igvn->register_new_node_with_optimizer(phi);
1482 return phi;
1483 }
1484
1485 //------------------------------Ideal------------------------------------------
1486 // If the load is from Field memory and the pointer is non-null, it might be possible to
1487 // zero out the control input.
1488 // If the offset is constant and the base is an object allocation,
1489 // try to hook me up to the exact initializing store.
1490 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1491 Node* p = MemNode::Ideal_common(phase, can_reshape);
1492 if (p) return (p == NodeSentinel) ? NULL : p;
1493
1494 Node* ctrl = in(MemNode::Control);
1495 Node* address = in(MemNode::Address);
1496
1497 // Skip up past a SafePoint control. Cannot do this for Stores because
1498 // pointer stores & cardmarks must stay on the same side of a SafePoint.
1499 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint &&
1500 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw ) {
1501 ctrl = ctrl->in(0);
1502 set_req(MemNode::Control,ctrl);
1503 }
1504
1505 intptr_t ignore = 0;
1506 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1507 if (base != NULL
1508 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
1509 // Check for useless control edge in some common special cases
1510 if (in(MemNode::Control) != NULL
1511 && can_remove_control()
1512 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1513 && all_controls_dominate(base, phase->C->start())) {
1514 // A method-invariant, non-null address (constant or 'this' argument).
1515 set_req(MemNode::Control, NULL);
1516 }
1517 }
1518
1519 Node* mem = in(MemNode::Memory);
1520 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1521
1522 if (can_reshape && (addr_t != NULL)) {
1523 // try to optimize our memory input
1524 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase);
1525 if (opt_mem != mem) {
1526 set_req(MemNode::Memory, opt_mem);
1527 if (phase->type( opt_mem ) == Type::TOP) return NULL;
1528 return this;
1529 }
1530 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1531 if ((t_oop != NULL) &&
1532 (t_oop->is_known_instance_field() ||
1533 t_oop->is_ptr_to_boxed_value())) {
1534 PhaseIterGVN *igvn = phase->is_IterGVN();
1535 if (igvn != NULL && igvn->_worklist.member(opt_mem)) {
1536 // Delay this transformation until memory Phi is processed.
1537 phase->is_IterGVN()->_worklist.push(this);
1538 return NULL;
1539 }
1540 // Split instance field load through Phi.
1541 Node* result = split_through_phi(phase);
1542 if (result != NULL) return result;
1543
1544 if (t_oop->is_ptr_to_boxed_value()) {
1545 Node* result = eliminate_autobox(phase);
1546 if (result != NULL) return result;
1547 }
1548 }
1549 }
1550
1551 // Check for prior store with a different base or offset; make Load
1552 // independent. Skip through any number of them. Bail out if the stores
1553 // are in an endless dead cycle and report no progress. This is a key
1554 // transform for Reflection. However, if after skipping through the Stores
1555 // we can't then fold up against a prior store do NOT do the transform as
1556 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
1557 // array memory alive twice: once for the hoisted Load and again after the
1558 // bypassed Store. This situation only works if EVERYBODY who does
1559 // anti-dependence work knows how to bypass. I.e. we need all
1560 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
1561 // the alias index stuff. So instead, peek through Stores and IFF we can
1562 // fold up, do so.
1563 Node* prev_mem = find_previous_store(phase);
1564 // Steps (a), (b): Walk past independent stores to find an exact match.
1565 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) {
1566 // (c) See if we can fold up on the spot, but don't fold up here.
1567 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
1568 // just return a prior value, which is done by Identity calls.
1569 if (can_see_stored_value(prev_mem, phase)) {
1570 // Make ready for step (d):
1571 set_req(MemNode::Memory, prev_mem);
1572 return this;
1573 }
1574 }
1575
1576 return NULL; // No further progress
1577 }
1578
1579 // Helper to recognize certain Klass fields which are invariant across
1580 // some group of array types (e.g., int[] or all T[] where T < Object).
1581 const Type*
1582 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1583 ciKlass* klass) const {
1584 if (tkls->offset() == in_bytes(Klass::modifier_flags_offset())) {
1585 // The field is Klass::_modifier_flags. Return its (constant) value.
1586 // (Folds up the 2nd indirection in aClassConstant.getModifiers().)
1587 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags");
1588 return TypeInt::make(klass->modifier_flags());
1589 }
1590 if (tkls->offset() == in_bytes(Klass::access_flags_offset())) {
1591 // The field is Klass::_access_flags. Return its (constant) value.
1592 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1593 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags");
1594 return TypeInt::make(klass->access_flags());
1595 }
1596 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) {
1597 // The field is Klass::_layout_helper. Return its constant value if known.
1598 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper");
1599 return TypeInt::make(klass->layout_helper());
1600 }
1601
1602 // No match.
1603 return NULL;
1604 }
1605
1606 // Try to constant-fold a stable array element.
1607 static const Type* fold_stable_ary_elem(const TypeAryPtr* ary, int off, BasicType loadbt) {
1608 assert(ary->const_oop(), "array should be constant");
1609 assert(ary->is_stable(), "array should be stable");
1610
1611 // Decode the results of GraphKit::array_element_address.
1612 ciArray* aobj = ary->const_oop()->as_array();
1613 ciConstant con = aobj->element_value_by_offset(off);
1614
1615 if (con.basic_type() != T_ILLEGAL && !con.is_null_or_zero()) {
1616 const Type* con_type = Type::make_from_constant(con);
1617 if (con_type != NULL) {
1618 if (con_type->isa_aryptr()) {
1619 // Join with the array element type, in case it is also stable.
1620 int dim = ary->stable_dimension();
1621 con_type = con_type->is_aryptr()->cast_to_stable(true, dim-1);
1622 }
1623 if (loadbt == T_NARROWOOP && con_type->isa_oopptr()) {
1624 con_type = con_type->make_narrowoop();
1625 }
1626 #ifndef PRODUCT
1627 if (TraceIterativeGVN) {
1628 tty->print("FoldStableValues: array element [off=%d]: con_type=", off);
1629 con_type->dump(); tty->cr();
1630 }
1631 #endif //PRODUCT
1632 return con_type;
1633 }
1634 }
1635 return NULL;
1636 }
1637
1638 //------------------------------Value-----------------------------------------
1639 const Type *LoadNode::Value( PhaseTransform *phase ) const {
1640 // Either input is TOP ==> the result is TOP
1641 Node* mem = in(MemNode::Memory);
1642 const Type *t1 = phase->type(mem);
1643 if (t1 == Type::TOP) return Type::TOP;
1644 Node* adr = in(MemNode::Address);
1645 const TypePtr* tp = phase->type(adr)->isa_ptr();
1646 if (tp == NULL || tp->empty()) return Type::TOP;
1647 int off = tp->offset();
1648 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
1649 Compile* C = phase->C;
1650
1651 // Try to guess loaded type from pointer type
1652 if (tp->isa_aryptr()) {
1653 const TypeAryPtr* ary = tp->is_aryptr();
1654 const Type* t = ary->elem();
1655
1656 // Determine whether the reference is beyond the header or not, by comparing
1657 // the offset against the offset of the start of the array's data.
1658 // Different array types begin at slightly different offsets (12 vs. 16).
1659 // We choose T_BYTE as an example base type that is least restrictive
1660 // as to alignment, which will therefore produce the smallest
1661 // possible base offset.
1662 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
1663 const bool off_beyond_header = ((uint)off >= (uint)min_base_off);
1664
1665 // Try to constant-fold a stable array element.
1666 if (FoldStableValues && ary->is_stable() && ary->const_oop() != NULL) {
1667 // Make sure the reference is not into the header and the offset is constant
1668 if (off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) {
1669 const Type* con_type = fold_stable_ary_elem(ary, off, memory_type());
1670 if (con_type != NULL) {
1671 return con_type;
1672 }
1673 }
1674 }
1675
1676 // Don't do this for integer types. There is only potential profit if
1677 // the element type t is lower than _type; that is, for int types, if _type is
1678 // more restrictive than t. This only happens here if one is short and the other
1679 // char (both 16 bits), and in those cases we've made an intentional decision
1680 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
1681 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
1682 //
1683 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
1684 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
1685 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
1686 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
1687 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
1688 // In fact, that could have been the original type of p1, and p1 could have
1689 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
1690 // expression (LShiftL quux 3) independently optimized to the constant 8.
1691 if ((t->isa_int() == NULL) && (t->isa_long() == NULL)
1692 && (_type->isa_vect() == NULL)
1693 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
1694 // t might actually be lower than _type, if _type is a unique
1695 // concrete subclass of abstract class t.
1696 if (off_beyond_header) { // is the offset beyond the header?
1697 const Type* jt = t->join_speculative(_type);
1698 // In any case, do not allow the join, per se, to empty out the type.
1699 if (jt->empty() && !t->empty()) {
1700 // This can happen if a interface-typed array narrows to a class type.
1701 jt = _type;
1702 }
1703 #ifdef ASSERT
1704 if (phase->C->eliminate_boxing() && adr->is_AddP()) {
1705 // The pointers in the autobox arrays are always non-null
1706 Node* base = adr->in(AddPNode::Base);
1707 if ((base != NULL) && base->is_DecodeN()) {
1708 // Get LoadN node which loads IntegerCache.cache field
1709 base = base->in(1);
1710 }
1711 if ((base != NULL) && base->is_Con()) {
1712 const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr();
1713 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1714 // It could be narrow oop
1715 assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity");
1716 }
1717 }
1718 }
1719 #endif
1720 return jt;
1721 }
1722 }
1723 } else if (tp->base() == Type::InstPtr) {
1724 ciEnv* env = C->env();
1725 const TypeInstPtr* tinst = tp->is_instptr();
1726 ciKlass* klass = tinst->klass();
1727 assert( off != Type::OffsetBot ||
1728 // arrays can be cast to Objects
1729 tp->is_oopptr()->klass()->is_java_lang_Object() ||
1730 // unsafe field access may not have a constant offset
1731 C->has_unsafe_access(),
1732 "Field accesses must be precise" );
1733 // For oop loads, we expect the _type to be precise
1734 if (klass == env->String_klass() &&
1735 adr->is_AddP() && off != Type::OffsetBot) {
1736 // For constant Strings treat the final fields as compile time constants.
1737 Node* base = adr->in(AddPNode::Base);
1738 const TypeOopPtr* t = phase->type(base)->isa_oopptr();
1739 if (t != NULL && t->singleton()) {
1740 ciField* field = env->String_klass()->get_field_by_offset(off, false);
1741 if (field != NULL && field->is_final()) {
1742 ciObject* string = t->const_oop();
1743 ciConstant constant = string->as_instance()->field_value(field);
1744 if (constant.basic_type() == T_INT) {
1745 return TypeInt::make(constant.as_int());
1746 } else if (constant.basic_type() == T_ARRAY) {
1747 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
1748 return TypeNarrowOop::make_from_constant(constant.as_object(), true);
1749 } else {
1750 return TypeOopPtr::make_from_constant(constant.as_object(), true);
1751 }
1752 }
1753 }
1754 }
1755 }
1756 // Optimizations for constant objects
1757 ciObject* const_oop = tinst->const_oop();
1758 if (const_oop != NULL) {
1759 // For constant Boxed value treat the target field as a compile time constant.
1760 if (tinst->is_ptr_to_boxed_value()) {
1761 return tinst->get_const_boxed_value();
1762 } else
1763 // For constant CallSites treat the target field as a compile time constant.
1764 if (const_oop->is_call_site()) {
1765 ciCallSite* call_site = const_oop->as_call_site();
1766 ciField* field = call_site->klass()->as_instance_klass()->get_field_by_offset(off, /*is_static=*/ false);
1767 if (field != NULL && field->is_call_site_target()) {
1768 ciMethodHandle* target = call_site->get_target();
1769 if (target != NULL) { // just in case
1770 ciConstant constant(T_OBJECT, target);
1771 const Type* t;
1772 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
1773 t = TypeNarrowOop::make_from_constant(constant.as_object(), true);
1774 } else {
1775 t = TypeOopPtr::make_from_constant(constant.as_object(), true);
1776 }
1777 // Add a dependence for invalidation of the optimization.
1778 if (!call_site->is_constant_call_site()) {
1779 C->dependencies()->assert_call_site_target_value(call_site, target);
1780 }
1781 return t;
1782 }
1783 }
1784 }
1785 }
1786 } else if (tp->base() == Type::KlassPtr) {
1787 assert( off != Type::OffsetBot ||
1788 // arrays can be cast to Objects
1789 tp->is_klassptr()->klass()->is_java_lang_Object() ||
1790 // also allow array-loading from the primary supertype
1791 // array during subtype checks
1792 Opcode() == Op_LoadKlass,
1793 "Field accesses must be precise" );
1794 // For klass/static loads, we expect the _type to be precise
1795 }
1796
1797 const TypeKlassPtr *tkls = tp->isa_klassptr();
1798 if (tkls != NULL && !StressReflectiveCode) {
1799 ciKlass* klass = tkls->klass();
1800 if (klass->is_loaded() && tkls->klass_is_exact()) {
1801 // We are loading a field from a Klass metaobject whose identity
1802 // is known at compile time (the type is "exact" or "precise").
1803 // Check for fields we know are maintained as constants by the VM.
1804 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) {
1805 // The field is Klass::_super_check_offset. Return its (constant) value.
1806 // (Folds up type checking code.)
1807 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
1808 return TypeInt::make(klass->super_check_offset());
1809 }
1810 // Compute index into primary_supers array
1811 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1812 // Check for overflowing; use unsigned compare to handle the negative case.
1813 if( depth < ciKlass::primary_super_limit() ) {
1814 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1815 // (Folds up type checking code.)
1816 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1817 ciKlass *ss = klass->super_of_depth(depth);
1818 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1819 }
1820 const Type* aift = load_array_final_field(tkls, klass);
1821 if (aift != NULL) return aift;
1822 if (tkls->offset() == in_bytes(ArrayKlass::component_mirror_offset())
1823 && klass->is_array_klass()) {
1824 // The field is ArrayKlass::_component_mirror. Return its (constant) value.
1825 // (Folds up aClassConstant.getComponentType, common in Arrays.copyOf.)
1826 assert(Opcode() == Op_LoadP, "must load an oop from _component_mirror");
1827 return TypeInstPtr::make(klass->as_array_klass()->component_mirror());
1828 }
1829 if (tkls->offset() == in_bytes(Klass::java_mirror_offset())) {
1830 // The field is Klass::_java_mirror. Return its (constant) value.
1831 // (Folds up the 2nd indirection in anObjConstant.getClass().)
1832 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
1833 return TypeInstPtr::make(klass->java_mirror());
1834 }
1835 }
1836
1837 // We can still check if we are loading from the primary_supers array at a
1838 // shallow enough depth. Even though the klass is not exact, entries less
1839 // than or equal to its super depth are correct.
1840 if (klass->is_loaded() ) {
1841 ciType *inner = klass;
1842 while( inner->is_obj_array_klass() )
1843 inner = inner->as_obj_array_klass()->base_element_type();
1844 if( inner->is_instance_klass() &&
1845 !inner->as_instance_klass()->flags().is_interface() ) {
1846 // Compute index into primary_supers array
1847 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1848 // Check for overflowing; use unsigned compare to handle the negative case.
1849 if( depth < ciKlass::primary_super_limit() &&
1850 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case
1851 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1852 // (Folds up type checking code.)
1853 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1854 ciKlass *ss = klass->super_of_depth(depth);
1855 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1856 }
1857 }
1858 }
1859
1860 // If the type is enough to determine that the thing is not an array,
1861 // we can give the layout_helper a positive interval type.
1862 // This will help short-circuit some reflective code.
1863 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())
1864 && !klass->is_array_klass() // not directly typed as an array
1865 && !klass->is_interface() // specifically not Serializable & Cloneable
1866 && !klass->is_java_lang_Object() // not the supertype of all T[]
1867 ) {
1868 // Note: When interfaces are reliable, we can narrow the interface
1869 // test to (klass != Serializable && klass != Cloneable).
1870 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
1871 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
1872 // The key property of this type is that it folds up tests
1873 // for array-ness, since it proves that the layout_helper is positive.
1874 // Thus, a generic value like the basic object layout helper works fine.
1875 return TypeInt::make(min_size, max_jint, Type::WidenMin);
1876 }
1877 }
1878
1879 // If we are loading from a freshly-allocated object, produce a zero,
1880 // if the load is provably beyond the header of the object.
1881 // (Also allow a variable load from a fresh array to produce zero.)
1882 const TypeOopPtr *tinst = tp->isa_oopptr();
1883 bool is_instance = (tinst != NULL) && tinst->is_known_instance_field();
1884 bool is_boxed_value = (tinst != NULL) && tinst->is_ptr_to_boxed_value();
1885 if (ReduceFieldZeroing || is_instance || is_boxed_value) {
1886 Node* value = can_see_stored_value(mem,phase);
1887 if (value != NULL && value->is_Con()) {
1888 assert(value->bottom_type()->higher_equal(_type),"sanity");
1889 return value->bottom_type();
1890 }
1891 }
1892
1893 if (is_instance) {
1894 // If we have an instance type and our memory input is the
1895 // programs's initial memory state, there is no matching store,
1896 // so just return a zero of the appropriate type
1897 Node *mem = in(MemNode::Memory);
1898 if (mem->is_Parm() && mem->in(0)->is_Start()) {
1899 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
1900 return Type::get_zero_type(_type->basic_type());
1901 }
1902 }
1903 return _type;
1904 }
1905
1906 //------------------------------match_edge-------------------------------------
1907 // Do we Match on this edge index or not? Match only the address.
1908 uint LoadNode::match_edge(uint idx) const {
1909 return idx == MemNode::Address;
1910 }
1911
1912 //--------------------------LoadBNode::Ideal--------------------------------------
1913 //
1914 // If the previous store is to the same address as this load,
1915 // and the value stored was larger than a byte, replace this load
1916 // with the value stored truncated to a byte. If no truncation is
1917 // needed, the replacement is done in LoadNode::Identity().
1918 //
1919 Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1920 Node* mem = in(MemNode::Memory);
1921 Node* value = can_see_stored_value(mem,phase);
1922 if( value && !phase->type(value)->higher_equal( _type ) ) {
1923 Node *result = phase->transform( new (phase->C) LShiftINode(value, phase->intcon(24)) );
1924 return new (phase->C) RShiftINode(result, phase->intcon(24));
1925 }
1926 // Identity call will handle the case where truncation is not needed.
1927 return LoadNode::Ideal(phase, can_reshape);
1928 }
1929
1930 const Type* LoadBNode::Value(PhaseTransform *phase) const {
1931 Node* mem = in(MemNode::Memory);
1932 Node* value = can_see_stored_value(mem,phase);
1933 if (value != NULL && value->is_Con() &&
1934 !value->bottom_type()->higher_equal(_type)) {
1935 // If the input to the store does not fit with the load's result type,
1936 // it must be truncated. We can't delay until Ideal call since
1937 // a singleton Value is needed for split_thru_phi optimization.
1938 int con = value->get_int();
1939 return TypeInt::make((con << 24) >> 24);
1940 }
1941 return LoadNode::Value(phase);
1942 }
1943
1944 //--------------------------LoadUBNode::Ideal-------------------------------------
1945 //
1946 // If the previous store is to the same address as this load,
1947 // and the value stored was larger than a byte, replace this load
1948 // with the value stored truncated to a byte. If no truncation is
1949 // needed, the replacement is done in LoadNode::Identity().
1950 //
1951 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
1952 Node* mem = in(MemNode::Memory);
1953 Node* value = can_see_stored_value(mem, phase);
1954 if (value && !phase->type(value)->higher_equal(_type))
1955 return new (phase->C) AndINode(value, phase->intcon(0xFF));
1956 // Identity call will handle the case where truncation is not needed.
1957 return LoadNode::Ideal(phase, can_reshape);
1958 }
1959
1960 const Type* LoadUBNode::Value(PhaseTransform *phase) const {
1961 Node* mem = in(MemNode::Memory);
1962 Node* value = can_see_stored_value(mem,phase);
1963 if (value != NULL && value->is_Con() &&
1964 !value->bottom_type()->higher_equal(_type)) {
1965 // If the input to the store does not fit with the load's result type,
1966 // it must be truncated. We can't delay until Ideal call since
1967 // a singleton Value is needed for split_thru_phi optimization.
1968 int con = value->get_int();
1969 return TypeInt::make(con & 0xFF);
1970 }
1971 return LoadNode::Value(phase);
1972 }
1973
1974 //--------------------------LoadUSNode::Ideal-------------------------------------
1975 //
1976 // If the previous store is to the same address as this load,
1977 // and the value stored was larger than a char, replace this load
1978 // with the value stored truncated to a char. If no truncation is
1979 // needed, the replacement is done in LoadNode::Identity().
1980 //
1981 Node *LoadUSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1982 Node* mem = in(MemNode::Memory);
1983 Node* value = can_see_stored_value(mem,phase);
1984 if( value && !phase->type(value)->higher_equal( _type ) )
1985 return new (phase->C) AndINode(value,phase->intcon(0xFFFF));
1986 // Identity call will handle the case where truncation is not needed.
1987 return LoadNode::Ideal(phase, can_reshape);
1988 }
1989
1990 const Type* LoadUSNode::Value(PhaseTransform *phase) const {
1991 Node* mem = in(MemNode::Memory);
1992 Node* value = can_see_stored_value(mem,phase);
1993 if (value != NULL && value->is_Con() &&
1994 !value->bottom_type()->higher_equal(_type)) {
1995 // If the input to the store does not fit with the load's result type,
1996 // it must be truncated. We can't delay until Ideal call since
1997 // a singleton Value is needed for split_thru_phi optimization.
1998 int con = value->get_int();
1999 return TypeInt::make(con & 0xFFFF);
2000 }
2001 return LoadNode::Value(phase);
2002 }
2003
2004 //--------------------------LoadSNode::Ideal--------------------------------------
2005 //
2006 // If the previous store is to the same address as this load,
2007 // and the value stored was larger than a short, replace this load
2008 // with the value stored truncated to a short. If no truncation is
2009 // needed, the replacement is done in LoadNode::Identity().
2010 //
2011 Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2012 Node* mem = in(MemNode::Memory);
2013 Node* value = can_see_stored_value(mem,phase);
2014 if( value && !phase->type(value)->higher_equal( _type ) ) {
2015 Node *result = phase->transform( new (phase->C) LShiftINode(value, phase->intcon(16)) );
2016 return new (phase->C) RShiftINode(result, phase->intcon(16));
2017 }
2018 // Identity call will handle the case where truncation is not needed.
2019 return LoadNode::Ideal(phase, can_reshape);
2020 }
2021
2022 const Type* LoadSNode::Value(PhaseTransform *phase) const {
2023 Node* mem = in(MemNode::Memory);
2024 Node* value = can_see_stored_value(mem,phase);
2025 if (value != NULL && value->is_Con() &&
2026 !value->bottom_type()->higher_equal(_type)) {
2027 // If the input to the store does not fit with the load's result type,
2028 // it must be truncated. We can't delay until Ideal call since
2029 // a singleton Value is needed for split_thru_phi optimization.
2030 int con = value->get_int();
2031 return TypeInt::make((con << 16) >> 16);
2032 }
2033 return LoadNode::Value(phase);
2034 }
2035
2036 //=============================================================================
2037 //----------------------------LoadKlassNode::make------------------------------
2038 // Polymorphic factory method:
2039 Node* LoadKlassNode::make(PhaseGVN& gvn, Node* ctl, Node *mem, Node *adr, const TypePtr* at, const TypeKlassPtr *tk) {
2040 Compile* C = gvn.C;
2041 // sanity check the alias category against the created node type
2042 const TypePtr *adr_type = adr->bottom_type()->isa_ptr();
2043 assert(adr_type != NULL, "expecting TypeKlassPtr");
2044 #ifdef _LP64
2045 if (adr_type->is_ptr_to_narrowklass()) {
2046 assert(UseCompressedClassPointers, "no compressed klasses");
2047 Node* load_klass = gvn.transform(new (C) LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowklass(), MemNode::unordered));
2048 return new (C) DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr());
2049 }
2050 #endif
2051 assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
2052 return new (C) LoadKlassNode(ctl, mem, adr, at, tk, MemNode::unordered);
2053 }
2054
2055 //------------------------------Value------------------------------------------
2056 const Type *LoadKlassNode::Value( PhaseTransform *phase ) const {
2057 return klass_value_common(phase);
2058 }
2059
2060 // In most cases, LoadKlassNode does not have the control input set. If the control
2061 // input is set, it must not be removed (by LoadNode::Ideal()).
2062 bool LoadKlassNode::can_remove_control() const {
2063 return false;
2064 }
2065
2066 const Type *LoadNode::klass_value_common( PhaseTransform *phase ) const {
2067 // Either input is TOP ==> the result is TOP
2068 const Type *t1 = phase->type( in(MemNode::Memory) );
2069 if (t1 == Type::TOP) return Type::TOP;
2070 Node *adr = in(MemNode::Address);
2071 const Type *t2 = phase->type( adr );
2072 if (t2 == Type::TOP) return Type::TOP;
2073 const TypePtr *tp = t2->is_ptr();
2074 if (TypePtr::above_centerline(tp->ptr()) ||
2075 tp->ptr() == TypePtr::Null) return Type::TOP;
2076
2077 // Return a more precise klass, if possible
2078 const TypeInstPtr *tinst = tp->isa_instptr();
2079 if (tinst != NULL) {
2080 ciInstanceKlass* ik = tinst->klass()->as_instance_klass();
2081 int offset = tinst->offset();
2082 if (ik == phase->C->env()->Class_klass()
2083 && (offset == java_lang_Class::klass_offset_in_bytes() ||
2084 offset == java_lang_Class::array_klass_offset_in_bytes())) {
2085 // We are loading a special hidden field from a Class mirror object,
2086 // the field which points to the VM's Klass metaobject.
2087 ciType* t = tinst->java_mirror_type();
2088 // java_mirror_type returns non-null for compile-time Class constants.
2089 if (t != NULL) {
2090 // constant oop => constant klass
2091 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
2092 if (t->is_void()) {
2093 // We cannot create a void array. Since void is a primitive type return null
2094 // klass. Users of this result need to do a null check on the returned klass.
2095 return TypePtr::NULL_PTR;
2096 }
2097 return TypeKlassPtr::make(ciArrayKlass::make(t));
2098 }
2099 if (!t->is_klass()) {
2100 // a primitive Class (e.g., int.class) has NULL for a klass field
2101 return TypePtr::NULL_PTR;
2102 }
2103 // (Folds up the 1st indirection in aClassConstant.getModifiers().)
2104 return TypeKlassPtr::make(t->as_klass());
2105 }
2106 // non-constant mirror, so we can't tell what's going on
2107 }
2108 if( !ik->is_loaded() )
2109 return _type; // Bail out if not loaded
2110 if (offset == oopDesc::klass_offset_in_bytes()) {
2111 if (tinst->klass_is_exact()) {
2112 return TypeKlassPtr::make(ik);
2113 }
2114 // See if we can become precise: no subklasses and no interface
2115 // (Note: We need to support verified interfaces.)
2116 if (!ik->is_interface() && !ik->has_subklass()) {
2117 //assert(!UseExactTypes, "this code should be useless with exact types");
2118 // Add a dependence; if any subclass added we need to recompile
2119 if (!ik->is_final()) {
2120 // %%% should use stronger assert_unique_concrete_subtype instead
2121 phase->C->dependencies()->assert_leaf_type(ik);
2122 }
2123 // Return precise klass
2124 return TypeKlassPtr::make(ik);
2125 }
2126
2127 // Return root of possible klass
2128 return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/);
2129 }
2130 }
2131
2132 // Check for loading klass from an array
2133 const TypeAryPtr *tary = tp->isa_aryptr();
2134 if( tary != NULL ) {
2135 ciKlass *tary_klass = tary->klass();
2136 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP
2137 && tary->offset() == oopDesc::klass_offset_in_bytes()) {
2138 if (tary->klass_is_exact()) {
2139 return TypeKlassPtr::make(tary_klass);
2140 }
2141 ciArrayKlass *ak = tary->klass()->as_array_klass();
2142 // If the klass is an object array, we defer the question to the
2143 // array component klass.
2144 if( ak->is_obj_array_klass() ) {
2145 assert( ak->is_loaded(), "" );
2146 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass();
2147 if( base_k->is_loaded() && base_k->is_instance_klass() ) {
2148 ciInstanceKlass* ik = base_k->as_instance_klass();
2149 // See if we can become precise: no subklasses and no interface
2150 if (!ik->is_interface() && !ik->has_subklass()) {
2151 //assert(!UseExactTypes, "this code should be useless with exact types");
2152 // Add a dependence; if any subclass added we need to recompile
2153 if (!ik->is_final()) {
2154 phase->C->dependencies()->assert_leaf_type(ik);
2155 }
2156 // Return precise array klass
2157 return TypeKlassPtr::make(ak);
2158 }
2159 }
2160 return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/);
2161 } else { // Found a type-array?
2162 //assert(!UseExactTypes, "this code should be useless with exact types");
2163 assert( ak->is_type_array_klass(), "" );
2164 return TypeKlassPtr::make(ak); // These are always precise
2165 }
2166 }
2167 }
2168
2169 // Check for loading klass from an array klass
2170 const TypeKlassPtr *tkls = tp->isa_klassptr();
2171 if (tkls != NULL && !StressReflectiveCode) {
2172 ciKlass* klass = tkls->klass();
2173 if( !klass->is_loaded() )
2174 return _type; // Bail out if not loaded
2175 if( klass->is_obj_array_klass() &&
2176 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) {
2177 ciKlass* elem = klass->as_obj_array_klass()->element_klass();
2178 // // Always returning precise element type is incorrect,
2179 // // e.g., element type could be object and array may contain strings
2180 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
2181
2182 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
2183 // according to the element type's subclassing.
2184 return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/);
2185 }
2186 if( klass->is_instance_klass() && tkls->klass_is_exact() &&
2187 tkls->offset() == in_bytes(Klass::super_offset())) {
2188 ciKlass* sup = klass->as_instance_klass()->super();
2189 // The field is Klass::_super. Return its (constant) value.
2190 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
2191 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR;
2192 }
2193 }
2194
2195 // Bailout case
2196 return LoadNode::Value(phase);
2197 }
2198
2199 //------------------------------Identity---------------------------------------
2200 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
2201 // Also feed through the klass in Allocate(...klass...)._klass.
2202 Node* LoadKlassNode::Identity( PhaseTransform *phase ) {
2203 return klass_identity_common(phase);
2204 }
2205
2206 Node* LoadNode::klass_identity_common(PhaseTransform *phase ) {
2207 Node* x = LoadNode::Identity(phase);
2208 if (x != this) return x;
2209
2210 // Take apart the address into an oop and and offset.
2211 // Return 'this' if we cannot.
2212 Node* adr = in(MemNode::Address);
2213 intptr_t offset = 0;
2214 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2215 if (base == NULL) return this;
2216 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
2217 if (toop == NULL) return this;
2218
2219 // We can fetch the klass directly through an AllocateNode.
2220 // This works even if the klass is not constant (clone or newArray).
2221 if (offset == oopDesc::klass_offset_in_bytes()) {
2222 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
2223 if (allocated_klass != NULL) {
2224 return allocated_klass;
2225 }
2226 }
2227
2228 // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*.
2229 // Simplify ak.component_mirror.array_klass to plain ak, ak an ArrayKlass.
2230 // See inline_native_Class_query for occurrences of these patterns.
2231 // Java Example: x.getClass().isAssignableFrom(y)
2232 // Java Example: Array.newInstance(x.getClass().getComponentType(), n)
2233 //
2234 // This improves reflective code, often making the Class
2235 // mirror go completely dead. (Current exception: Class
2236 // mirrors may appear in debug info, but we could clean them out by
2237 // introducing a new debug info operator for Klass*.java_mirror).
2238 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass()
2239 && (offset == java_lang_Class::klass_offset_in_bytes() ||
2240 offset == java_lang_Class::array_klass_offset_in_bytes())) {
2241 // We are loading a special hidden field from a Class mirror,
2242 // the field which points to its Klass or ArrayKlass metaobject.
2243 if (base->is_Load()) {
2244 Node* adr2 = base->in(MemNode::Address);
2245 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2246 if (tkls != NULL && !tkls->empty()
2247 && (tkls->klass()->is_instance_klass() ||
2248 tkls->klass()->is_array_klass())
2249 && adr2->is_AddP()
2250 ) {
2251 int mirror_field = in_bytes(Klass::java_mirror_offset());
2252 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
2253 mirror_field = in_bytes(ArrayKlass::component_mirror_offset());
2254 }
2255 if (tkls->offset() == mirror_field) {
2256 return adr2->in(AddPNode::Base);
2257 }
2258 }
2259 }
2260 }
2261
2262 return this;
2263 }
2264
2265
2266 //------------------------------Value------------------------------------------
2267 const Type *LoadNKlassNode::Value( PhaseTransform *phase ) const {
2268 const Type *t = klass_value_common(phase);
2269 if (t == Type::TOP)
2270 return t;
2271
2272 return t->make_narrowklass();
2273 }
2274
2275 //------------------------------Identity---------------------------------------
2276 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
2277 // Also feed through the klass in Allocate(...klass...)._klass.
2278 Node* LoadNKlassNode::Identity( PhaseTransform *phase ) {
2279 Node *x = klass_identity_common(phase);
2280
2281 const Type *t = phase->type( x );
2282 if( t == Type::TOP ) return x;
2283 if( t->isa_narrowklass()) return x;
2284 assert (!t->isa_narrowoop(), "no narrow oop here");
2285
2286 return phase->transform(new (phase->C) EncodePKlassNode(x, t->make_narrowklass()));
2287 }
2288
2289 //------------------------------Value-----------------------------------------
2290 const Type *LoadRangeNode::Value( PhaseTransform *phase ) const {
2291 // Either input is TOP ==> the result is TOP
2292 const Type *t1 = phase->type( in(MemNode::Memory) );
2293 if( t1 == Type::TOP ) return Type::TOP;
2294 Node *adr = in(MemNode::Address);
2295 const Type *t2 = phase->type( adr );
2296 if( t2 == Type::TOP ) return Type::TOP;
2297 const TypePtr *tp = t2->is_ptr();
2298 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
2299 const TypeAryPtr *tap = tp->isa_aryptr();
2300 if( !tap ) return _type;
2301 return tap->size();
2302 }
2303
2304 //-------------------------------Ideal---------------------------------------
2305 // Feed through the length in AllocateArray(...length...)._length.
2306 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2307 Node* p = MemNode::Ideal_common(phase, can_reshape);
2308 if (p) return (p == NodeSentinel) ? NULL : p;
2309
2310 // Take apart the address into an oop and and offset.
2311 // Return 'this' if we cannot.
2312 Node* adr = in(MemNode::Address);
2313 intptr_t offset = 0;
2314 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2315 if (base == NULL) return NULL;
2316 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2317 if (tary == NULL) return NULL;
2318
2319 // We can fetch the length directly through an AllocateArrayNode.
2320 // This works even if the length is not constant (clone or newArray).
2321 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2322 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2323 if (alloc != NULL) {
2324 Node* allocated_length = alloc->Ideal_length();
2325 Node* len = alloc->make_ideal_length(tary, phase);
2326 if (allocated_length != len) {
2327 // New CastII improves on this.
2328 return len;
2329 }
2330 }
2331 }
2332
2333 return NULL;
2334 }
2335
2336 //------------------------------Identity---------------------------------------
2337 // Feed through the length in AllocateArray(...length...)._length.
2338 Node* LoadRangeNode::Identity( PhaseTransform *phase ) {
2339 Node* x = LoadINode::Identity(phase);
2340 if (x != this) return x;
2341
2342 // Take apart the address into an oop and and offset.
2343 // Return 'this' if we cannot.
2344 Node* adr = in(MemNode::Address);
2345 intptr_t offset = 0;
2346 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2347 if (base == NULL) return this;
2348 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2349 if (tary == NULL) return this;
2350
2351 // We can fetch the length directly through an AllocateArrayNode.
2352 // This works even if the length is not constant (clone or newArray).
2353 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2354 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2355 if (alloc != NULL) {
2356 Node* allocated_length = alloc->Ideal_length();
2357 // Do not allow make_ideal_length to allocate a CastII node.
2358 Node* len = alloc->make_ideal_length(tary, phase, false);
2359 if (allocated_length == len) {
2360 // Return allocated_length only if it would not be improved by a CastII.
2361 return allocated_length;
2362 }
2363 }
2364 }
2365
2366 return this;
2367
2368 }
2369
2370 //=============================================================================
2371 //---------------------------StoreNode::make-----------------------------------
2372 // Polymorphic factory method:
2373 StoreNode* StoreNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt, MemOrd mo) {
2374 assert((mo == unordered || mo == release), "unexpected");
2375 Compile* C = gvn.C;
2376 assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2377 ctl != NULL, "raw memory operations should have control edge");
2378
2379 switch (bt) {
2380 case T_BOOLEAN: val = gvn.transform(new (C) AndINode(val, gvn.intcon(0x1))); // Fall through to T_BYTE case
2381 case T_BYTE: return new (C) StoreBNode(ctl, mem, adr, adr_type, val, mo);
2382 case T_INT: return new (C) StoreINode(ctl, mem, adr, adr_type, val, mo);
2383 case T_CHAR:
2384 case T_SHORT: return new (C) StoreCNode(ctl, mem, adr, adr_type, val, mo);
2385 case T_LONG: return new (C) StoreLNode(ctl, mem, adr, adr_type, val, mo);
2386 case T_FLOAT: return new (C) StoreFNode(ctl, mem, adr, adr_type, val, mo);
2387 case T_DOUBLE: return new (C) StoreDNode(ctl, mem, adr, adr_type, val, mo);
2388 case T_METADATA:
2389 case T_ADDRESS:
2390 case T_OBJECT:
2391 #ifdef _LP64
2392 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
2393 val = gvn.transform(new (C) EncodePNode(val, val->bottom_type()->make_narrowoop()));
2394 return new (C) StoreNNode(ctl, mem, adr, adr_type, val, mo);
2395 } else if (adr->bottom_type()->is_ptr_to_narrowklass() ||
2396 (UseCompressedClassPointers && val->bottom_type()->isa_klassptr() &&
2397 adr->bottom_type()->isa_rawptr())) {
2398 val = gvn.transform(new (C) EncodePKlassNode(val, val->bottom_type()->make_narrowklass()));
2399 return new (C) StoreNKlassNode(ctl, mem, adr, adr_type, val, mo);
2400 }
2401 #endif
2402 {
2403 return new (C) StorePNode(ctl, mem, adr, adr_type, val, mo);
2404 }
2405 }
2406 ShouldNotReachHere();
2407 return (StoreNode*)NULL;
2408 }
2409
2410 StoreLNode* StoreLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
2411 bool require_atomic = true;
2412 return new (C) StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
2413 }
2414
2415 StoreDNode* StoreDNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
2416 bool require_atomic = true;
2417 return new (C) StoreDNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
2418 }
2419
2420
2421 //--------------------------bottom_type----------------------------------------
2422 const Type *StoreNode::bottom_type() const {
2423 return Type::MEMORY;
2424 }
2425
2426 //------------------------------hash-------------------------------------------
2427 uint StoreNode::hash() const {
2428 // unroll addition of interesting fields
2429 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2430
2431 // Since they are not commoned, do not hash them:
2432 return NO_HASH;
2433 }
2434
2435 //------------------------------Ideal------------------------------------------
2436 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
2437 // When a store immediately follows a relevant allocation/initialization,
2438 // try to capture it into the initialization, or hoist it above.
2439 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2440 Node* p = MemNode::Ideal_common(phase, can_reshape);
2441 if (p) return (p == NodeSentinel) ? NULL : p;
2442
2443 Node* mem = in(MemNode::Memory);
2444 Node* address = in(MemNode::Address);
2445
2446 // Back-to-back stores to same address? Fold em up. Generally
2447 // unsafe if I have intervening uses... Also disallowed for StoreCM
2448 // since they must follow each StoreP operation. Redundant StoreCMs
2449 // are eliminated just before matching in final_graph_reshape.
2450 if (mem->is_Store() && mem->in(MemNode::Address)->eqv_uncast(address) &&
2451 mem->Opcode() != Op_StoreCM) {
2452 // Looking at a dead closed cycle of memory?
2453 assert(mem != mem->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
2454
2455 assert(Opcode() == mem->Opcode() ||
2456 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw,
2457 "no mismatched stores, except on raw memory");
2458
2459 if (mem->outcnt() == 1 && // check for intervening uses
2460 mem->as_Store()->memory_size() <= this->memory_size()) {
2461 // If anybody other than 'this' uses 'mem', we cannot fold 'mem' away.
2462 // For example, 'mem' might be the final state at a conditional return.
2463 // Or, 'mem' might be used by some node which is live at the same time
2464 // 'this' is live, which might be unschedulable. So, require exactly
2465 // ONE user, the 'this' store, until such time as we clone 'mem' for
2466 // each of 'mem's uses (thus making the exactly-1-user-rule hold true).
2467 if (can_reshape) { // (%%% is this an anachronism?)
2468 set_req_X(MemNode::Memory, mem->in(MemNode::Memory),
2469 phase->is_IterGVN());
2470 } else {
2471 // It's OK to do this in the parser, since DU info is always accurate,
2472 // and the parser always refers to nodes via SafePointNode maps.
2473 set_req(MemNode::Memory, mem->in(MemNode::Memory));
2474 }
2475 return this;
2476 }
2477 }
2478
2479 // Capture an unaliased, unconditional, simple store into an initializer.
2480 // Or, if it is independent of the allocation, hoist it above the allocation.
2481 if (ReduceFieldZeroing && /*can_reshape &&*/
2482 mem->is_Proj() && mem->in(0)->is_Initialize()) {
2483 InitializeNode* init = mem->in(0)->as_Initialize();
2484 intptr_t offset = init->can_capture_store(this, phase, can_reshape);
2485 if (offset > 0) {
2486 Node* moved = init->capture_store(this, offset, phase, can_reshape);
2487 // If the InitializeNode captured me, it made a raw copy of me,
2488 // and I need to disappear.
2489 if (moved != NULL) {
2490 // %%% hack to ensure that Ideal returns a new node:
2491 mem = MergeMemNode::make(phase->C, mem);
2492 return mem; // fold me away
2493 }
2494 }
2495 }
2496
2497 return NULL; // No further progress
2498 }
2499
2500 //------------------------------Value-----------------------------------------
2501 const Type *StoreNode::Value( PhaseTransform *phase ) const {
2502 // Either input is TOP ==> the result is TOP
2503 const Type *t1 = phase->type( in(MemNode::Memory) );
2504 if( t1 == Type::TOP ) return Type::TOP;
2505 const Type *t2 = phase->type( in(MemNode::Address) );
2506 if( t2 == Type::TOP ) return Type::TOP;
2507 const Type *t3 = phase->type( in(MemNode::ValueIn) );
2508 if( t3 == Type::TOP ) return Type::TOP;
2509 return Type::MEMORY;
2510 }
2511
2512 //------------------------------Identity---------------------------------------
2513 // Remove redundant stores:
2514 // Store(m, p, Load(m, p)) changes to m.
2515 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
2516 Node *StoreNode::Identity( PhaseTransform *phase ) {
2517 Node* mem = in(MemNode::Memory);
2518 Node* adr = in(MemNode::Address);
2519 Node* val = in(MemNode::ValueIn);
2520
2521 // Load then Store? Then the Store is useless
2522 if (val->is_Load() &&
2523 val->in(MemNode::Address)->eqv_uncast(adr) &&
2524 val->in(MemNode::Memory )->eqv_uncast(mem) &&
2525 val->as_Load()->store_Opcode() == Opcode()) {
2526 return mem;
2527 }
2528
2529 // Two stores in a row of the same value?
2530 if (mem->is_Store() &&
2531 mem->in(MemNode::Address)->eqv_uncast(adr) &&
2532 mem->in(MemNode::ValueIn)->eqv_uncast(val) &&
2533 mem->Opcode() == Opcode()) {
2534 return mem;
2535 }
2536
2537 // Store of zero anywhere into a freshly-allocated object?
2538 // Then the store is useless.
2539 // (It must already have been captured by the InitializeNode.)
2540 if (ReduceFieldZeroing && phase->type(val)->is_zero_type()) {
2541 // a newly allocated object is already all-zeroes everywhere
2542 if (mem->is_Proj() && mem->in(0)->is_Allocate()) {
2543 return mem;
2544 }
2545
2546 // the store may also apply to zero-bits in an earlier object
2547 Node* prev_mem = find_previous_store(phase);
2548 // Steps (a), (b): Walk past independent stores to find an exact match.
2549 if (prev_mem != NULL) {
2550 Node* prev_val = can_see_stored_value(prev_mem, phase);
2551 if (prev_val != NULL && phase->eqv(prev_val, val)) {
2552 // prev_val and val might differ by a cast; it would be good
2553 // to keep the more informative of the two.
2554 return mem;
2555 }
2556 }
2557 }
2558
2559 return this;
2560 }
2561
2562 //------------------------------match_edge-------------------------------------
2563 // Do we Match on this edge index or not? Match only memory & value
2564 uint StoreNode::match_edge(uint idx) const {
2565 return idx == MemNode::Address || idx == MemNode::ValueIn;
2566 }
2567
2568 //------------------------------cmp--------------------------------------------
2569 // Do not common stores up together. They generally have to be split
2570 // back up anyways, so do not bother.
2571 uint StoreNode::cmp( const Node &n ) const {
2572 return (&n == this); // Always fail except on self
2573 }
2574
2575 //------------------------------Ideal_masked_input-----------------------------
2576 // Check for a useless mask before a partial-word store
2577 // (StoreB ... (AndI valIn conIa) )
2578 // If (conIa & mask == mask) this simplifies to
2579 // (StoreB ... (valIn) )
2580 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
2581 Node *val = in(MemNode::ValueIn);
2582 if( val->Opcode() == Op_AndI ) {
2583 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2584 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
2585 set_req(MemNode::ValueIn, val->in(1));
2586 return this;
2587 }
2588 }
2589 return NULL;
2590 }
2591
2592
2593 //------------------------------Ideal_sign_extended_input----------------------
2594 // Check for useless sign-extension before a partial-word store
2595 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) )
2596 // If (conIL == conIR && conIR <= num_bits) this simplifies to
2597 // (StoreB ... (valIn) )
2598 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) {
2599 Node *val = in(MemNode::ValueIn);
2600 if( val->Opcode() == Op_RShiftI ) {
2601 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2602 if( t && t->is_con() && (t->get_con() <= num_bits) ) {
2603 Node *shl = val->in(1);
2604 if( shl->Opcode() == Op_LShiftI ) {
2605 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int();
2606 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) {
2607 set_req(MemNode::ValueIn, shl->in(1));
2608 return this;
2609 }
2610 }
2611 }
2612 }
2613 return NULL;
2614 }
2615
2616 //------------------------------value_never_loaded-----------------------------------
2617 // Determine whether there are any possible loads of the value stored.
2618 // For simplicity, we actually check if there are any loads from the
2619 // address stored to, not just for loads of the value stored by this node.
2620 //
2621 bool StoreNode::value_never_loaded( PhaseTransform *phase) const {
2622 Node *adr = in(Address);
2623 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
2624 if (adr_oop == NULL)
2625 return false;
2626 if (!adr_oop->is_known_instance_field())
2627 return false; // if not a distinct instance, there may be aliases of the address
2628 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
2629 Node *use = adr->fast_out(i);
2630 int opc = use->Opcode();
2631 if (use->is_Load() || use->is_LoadStore()) {
2632 return false;
2633 }
2634 }
2635 return true;
2636 }
2637
2638 //=============================================================================
2639 //------------------------------Ideal------------------------------------------
2640 // If the store is from an AND mask that leaves the low bits untouched, then
2641 // we can skip the AND operation. If the store is from a sign-extension
2642 // (a left shift, then right shift) we can skip both.
2643 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
2644 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
2645 if( progress != NULL ) return progress;
2646
2647 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
2648 if( progress != NULL ) return progress;
2649
2650 // Finally check the default case
2651 return StoreNode::Ideal(phase, can_reshape);
2652 }
2653
2654 //=============================================================================
2655 //------------------------------Ideal------------------------------------------
2656 // If the store is from an AND mask that leaves the low bits untouched, then
2657 // we can skip the AND operation
2658 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
2659 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
2660 if( progress != NULL ) return progress;
2661
2662 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
2663 if( progress != NULL ) return progress;
2664
2665 // Finally check the default case
2666 return StoreNode::Ideal(phase, can_reshape);
2667 }
2668
2669 //=============================================================================
2670 //------------------------------Identity---------------------------------------
2671 Node *StoreCMNode::Identity( PhaseTransform *phase ) {
2672 // No need to card mark when storing a null ptr
2673 Node* my_store = in(MemNode::OopStore);
2674 if (my_store->is_Store()) {
2675 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) );
2676 if( t1 == TypePtr::NULL_PTR ) {
2677 return in(MemNode::Memory);
2678 }
2679 }
2680 return this;
2681 }
2682
2683 //=============================================================================
2684 //------------------------------Ideal---------------------------------------
2685 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){
2686 Node* progress = StoreNode::Ideal(phase, can_reshape);
2687 if (progress != NULL) return progress;
2688
2689 Node* my_store = in(MemNode::OopStore);
2690 if (my_store->is_MergeMem()) {
2691 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx());
2692 set_req(MemNode::OopStore, mem);
2693 return this;
2694 }
2695
2696 return NULL;
2697 }
2698
2699 //------------------------------Value-----------------------------------------
2700 const Type *StoreCMNode::Value( PhaseTransform *phase ) const {
2701 // Either input is TOP ==> the result is TOP
2702 const Type *t = phase->type( in(MemNode::Memory) );
2703 if( t == Type::TOP ) return Type::TOP;
2704 t = phase->type( in(MemNode::Address) );
2705 if( t == Type::TOP ) return Type::TOP;
2706 t = phase->type( in(MemNode::ValueIn) );
2707 if( t == Type::TOP ) return Type::TOP;
2708 // If extra input is TOP ==> the result is TOP
2709 t = phase->type( in(MemNode::OopStore) );
2710 if( t == Type::TOP ) return Type::TOP;
2711
2712 return StoreNode::Value( phase );
2713 }
2714
2715
2716 //=============================================================================
2717 //----------------------------------SCMemProjNode------------------------------
2718 const Type * SCMemProjNode::Value( PhaseTransform *phase ) const
2719 {
2720 return bottom_type();
2721 }
2722
2723 //=============================================================================
2724 //----------------------------------LoadStoreNode------------------------------
2725 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required )
2726 : Node(required),
2727 _type(rt),
2728 _adr_type(at)
2729 {
2730 init_req(MemNode::Control, c );
2731 init_req(MemNode::Memory , mem);
2732 init_req(MemNode::Address, adr);
2733 init_req(MemNode::ValueIn, val);
2734 init_class_id(Class_LoadStore);
2735 }
2736
2737 uint LoadStoreNode::ideal_reg() const {
2738 return _type->ideal_reg();
2739 }
2740
2741 bool LoadStoreNode::result_not_used() const {
2742 for( DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++ ) {
2743 Node *x = fast_out(i);
2744 if (x->Opcode() == Op_SCMemProj) continue;
2745 return false;
2746 }
2747 return true;
2748 }
2749
2750 uint LoadStoreNode::size_of() const { return sizeof(*this); }
2751
2752 //=============================================================================
2753 //----------------------------------LoadStoreConditionalNode--------------------
2754 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, NULL, TypeInt::BOOL, 5) {
2755 init_req(ExpectedIn, ex );
2756 }
2757
2758 //=============================================================================
2759 //-------------------------------adr_type--------------------------------------
2760 // Do we Match on this edge index or not? Do not match memory
2761 const TypePtr* ClearArrayNode::adr_type() const {
2762 Node *adr = in(3);
2763 return MemNode::calculate_adr_type(adr->bottom_type());
2764 }
2765
2766 //------------------------------match_edge-------------------------------------
2767 // Do we Match on this edge index or not? Do not match memory
2768 uint ClearArrayNode::match_edge(uint idx) const {
2769 return idx > 1;
2770 }
2771
2772 //------------------------------Identity---------------------------------------
2773 // Clearing a zero length array does nothing
2774 Node *ClearArrayNode::Identity( PhaseTransform *phase ) {
2775 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
2776 }
2777
2778 //------------------------------Idealize---------------------------------------
2779 // Clearing a short array is faster with stores
2780 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape){
2781 const int unit = BytesPerLong;
2782 const TypeX* t = phase->type(in(2))->isa_intptr_t();
2783 if (!t) return NULL;
2784 if (!t->is_con()) return NULL;
2785 intptr_t raw_count = t->get_con();
2786 intptr_t size = raw_count;
2787 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
2788 // Clearing nothing uses the Identity call.
2789 // Negative clears are possible on dead ClearArrays
2790 // (see jck test stmt114.stmt11402.val).
2791 if (size <= 0 || size % unit != 0) return NULL;
2792 intptr_t count = size / unit;
2793 // Length too long; use fast hardware clear
2794 if (size > Matcher::init_array_short_size) return NULL;
2795 Node *mem = in(1);
2796 if( phase->type(mem)==Type::TOP ) return NULL;
2797 Node *adr = in(3);
2798 const Type* at = phase->type(adr);
2799 if( at==Type::TOP ) return NULL;
2800 const TypePtr* atp = at->isa_ptr();
2801 // adjust atp to be the correct array element address type
2802 if (atp == NULL) atp = TypePtr::BOTTOM;
2803 else atp = atp->add_offset(Type::OffsetBot);
2804 // Get base for derived pointer purposes
2805 if( adr->Opcode() != Op_AddP ) Unimplemented();
2806 Node *base = adr->in(1);
2807
2808 Node *zero = phase->makecon(TypeLong::ZERO);
2809 Node *off = phase->MakeConX(BytesPerLong);
2810 mem = new (phase->C) StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
2811 count--;
2812 while( count-- ) {
2813 mem = phase->transform(mem);
2814 adr = phase->transform(new (phase->C) AddPNode(base,adr,off));
2815 mem = new (phase->C) StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
2816 }
2817 return mem;
2818 }
2819
2820 //----------------------------step_through----------------------------------
2821 // Return allocation input memory edge if it is different instance
2822 // or itself if it is the one we are looking for.
2823 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) {
2824 Node* n = *np;
2825 assert(n->is_ClearArray(), "sanity");
2826 intptr_t offset;
2827 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
2828 // This method is called only before Allocate nodes are expanded during
2829 // macro nodes expansion. Before that ClearArray nodes are only generated
2830 // in LibraryCallKit::generate_arraycopy() which follows allocations.
2831 assert(alloc != NULL, "should have allocation");
2832 if (alloc->_idx == instance_id) {
2833 // Can not bypass initialization of the instance we are looking for.
2834 return false;
2835 }
2836 // Otherwise skip it.
2837 InitializeNode* init = alloc->initialization();
2838 if (init != NULL)
2839 *np = init->in(TypeFunc::Memory);
2840 else
2841 *np = alloc->in(TypeFunc::Memory);
2842 return true;
2843 }
2844
2845 //----------------------------clear_memory-------------------------------------
2846 // Generate code to initialize object storage to zero.
2847 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2848 intptr_t start_offset,
2849 Node* end_offset,
2850 PhaseGVN* phase) {
2851 Compile* C = phase->C;
2852 intptr_t offset = start_offset;
2853
2854 int unit = BytesPerLong;
2855 if ((offset % unit) != 0) {
2856 Node* adr = new (C) AddPNode(dest, dest, phase->MakeConX(offset));
2857 adr = phase->transform(adr);
2858 const TypePtr* atp = TypeRawPtr::BOTTOM;
2859 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
2860 mem = phase->transform(mem);
2861 offset += BytesPerInt;
2862 }
2863 assert((offset % unit) == 0, "");
2864
2865 // Initialize the remaining stuff, if any, with a ClearArray.
2866 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase);
2867 }
2868
2869 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2870 Node* start_offset,
2871 Node* end_offset,
2872 PhaseGVN* phase) {
2873 if (start_offset == end_offset) {
2874 // nothing to do
2875 return mem;
2876 }
2877
2878 Compile* C = phase->C;
2879 int unit = BytesPerLong;
2880 Node* zbase = start_offset;
2881 Node* zend = end_offset;
2882
2883 // Scale to the unit required by the CPU:
2884 if (!Matcher::init_array_count_is_in_bytes) {
2885 Node* shift = phase->intcon(exact_log2(unit));
2886 zbase = phase->transform( new(C) URShiftXNode(zbase, shift) );
2887 zend = phase->transform( new(C) URShiftXNode(zend, shift) );
2888 }
2889
2890 // Bulk clear double-words
2891 Node* zsize = phase->transform( new(C) SubXNode(zend, zbase) );
2892 Node* adr = phase->transform( new(C) AddPNode(dest, dest, start_offset) );
2893 mem = new (C) ClearArrayNode(ctl, mem, zsize, adr);
2894 return phase->transform(mem);
2895 }
2896
2897 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2898 intptr_t start_offset,
2899 intptr_t end_offset,
2900 PhaseGVN* phase) {
2901 if (start_offset == end_offset) {
2902 // nothing to do
2903 return mem;
2904 }
2905
2906 Compile* C = phase->C;
2907 assert((end_offset % BytesPerInt) == 0, "odd end offset");
2908 intptr_t done_offset = end_offset;
2909 if ((done_offset % BytesPerLong) != 0) {
2910 done_offset -= BytesPerInt;
2911 }
2912 if (done_offset > start_offset) {
2913 mem = clear_memory(ctl, mem, dest,
2914 start_offset, phase->MakeConX(done_offset), phase);
2915 }
2916 if (done_offset < end_offset) { // emit the final 32-bit store
2917 Node* adr = new (C) AddPNode(dest, dest, phase->MakeConX(done_offset));
2918 adr = phase->transform(adr);
2919 const TypePtr* atp = TypeRawPtr::BOTTOM;
2920 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
2921 mem = phase->transform(mem);
2922 done_offset += BytesPerInt;
2923 }
2924 assert(done_offset == end_offset, "");
2925 return mem;
2926 }
2927
2928 //=============================================================================
2929 // Do not match memory edge.
2930 uint StrIntrinsicNode::match_edge(uint idx) const {
2931 return idx == 2 || idx == 3;
2932 }
2933
2934 //------------------------------Ideal------------------------------------------
2935 // Return a node which is more "ideal" than the current node. Strip out
2936 // control copies
2937 Node *StrIntrinsicNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2938 if (remove_dead_region(phase, can_reshape)) return this;
2939 // Don't bother trying to transform a dead node
2940 if (in(0) && in(0)->is_top()) return NULL;
2941
2942 if (can_reshape) {
2943 Node* mem = phase->transform(in(MemNode::Memory));
2944 // If transformed to a MergeMem, get the desired slice
2945 uint alias_idx = phase->C->get_alias_index(adr_type());
2946 mem = mem->is_MergeMem() ? mem->as_MergeMem()->memory_at(alias_idx) : mem;
2947 if (mem != in(MemNode::Memory)) {
2948 set_req(MemNode::Memory, mem);
2949 return this;
2950 }
2951 }
2952 return NULL;
2953 }
2954
2955 //------------------------------Value------------------------------------------
2956 const Type *StrIntrinsicNode::Value( PhaseTransform *phase ) const {
2957 if (in(0) && phase->type(in(0)) == Type::TOP) return Type::TOP;
2958 return bottom_type();
2959 }
2960
2961 //=============================================================================
2962 //------------------------------match_edge-------------------------------------
2963 // Do not match memory edge
2964 uint EncodeISOArrayNode::match_edge(uint idx) const {
2965 return idx == 2 || idx == 3; // EncodeISOArray src (Binary dst len)
2966 }
2967
2968 //------------------------------Ideal------------------------------------------
2969 // Return a node which is more "ideal" than the current node. Strip out
2970 // control copies
2971 Node *EncodeISOArrayNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2972 return remove_dead_region(phase, can_reshape) ? this : NULL;
2973 }
2974
2975 //------------------------------Value------------------------------------------
2976 const Type *EncodeISOArrayNode::Value(PhaseTransform *phase) const {
2977 if (in(0) && phase->type(in(0)) == Type::TOP) return Type::TOP;
2978 return bottom_type();
2979 }
2980
2981 //=============================================================================
2982 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
2983 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)),
2984 _adr_type(C->get_adr_type(alias_idx))
2985 {
2986 init_class_id(Class_MemBar);
2987 Node* top = C->top();
2988 init_req(TypeFunc::I_O,top);
2989 init_req(TypeFunc::FramePtr,top);
2990 init_req(TypeFunc::ReturnAdr,top);
2991 if (precedent != NULL)
2992 init_req(TypeFunc::Parms, precedent);
2993 }
2994
2995 //------------------------------cmp--------------------------------------------
2996 uint MemBarNode::hash() const { return NO_HASH; }
2997 uint MemBarNode::cmp( const Node &n ) const {
2998 return (&n == this); // Always fail except on self
2999 }
3000
3001 //------------------------------make-------------------------------------------
3002 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
3003 switch (opcode) {
3004 case Op_MemBarAcquire: return new(C) MemBarAcquireNode(C, atp, pn);
3005 case Op_LoadFence: return new(C) LoadFenceNode(C, atp, pn);
3006 case Op_MemBarRelease: return new(C) MemBarReleaseNode(C, atp, pn);
3007 case Op_StoreFence: return new(C) StoreFenceNode(C, atp, pn);
3008 case Op_MemBarAcquireLock: return new(C) MemBarAcquireLockNode(C, atp, pn);
3009 case Op_MemBarReleaseLock: return new(C) MemBarReleaseLockNode(C, atp, pn);
3010 case Op_MemBarVolatile: return new(C) MemBarVolatileNode(C, atp, pn);
3011 case Op_MemBarCPUOrder: return new(C) MemBarCPUOrderNode(C, atp, pn);
3012 case Op_Initialize: return new(C) InitializeNode(C, atp, pn);
3013 case Op_MemBarStoreStore: return new(C) MemBarStoreStoreNode(C, atp, pn);
3014 default: ShouldNotReachHere(); return NULL;
3015 }
3016 }
3017
3018 //------------------------------Ideal------------------------------------------
3019 // Return a node which is more "ideal" than the current node. Strip out
3020 // control copies
3021 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3022 if (remove_dead_region(phase, can_reshape)) return this;
3023 // Don't bother trying to transform a dead node
3024 if (in(0) && in(0)->is_top()) {
3025 return NULL;
3026 }
3027
3028 // Eliminate volatile MemBars for scalar replaced objects.
3029 if (can_reshape && req() == (Precedent+1)) {
3030 bool eliminate = false;
3031 int opc = Opcode();
3032 if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) {
3033 // Volatile field loads and stores.
3034 Node* my_mem = in(MemBarNode::Precedent);
3035 // The MembarAquire may keep an unused LoadNode alive through the Precedent edge
3036 if ((my_mem != NULL) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) {
3037 // if the Precedent is a decodeN and its input (a Load) is used at more than one place,
3038 // replace this Precedent (decodeN) with the Load instead.
3039 if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1)) {
3040 Node* load_node = my_mem->in(1);
3041 set_req(MemBarNode::Precedent, load_node);
3042 phase->is_IterGVN()->_worklist.push(my_mem);
3043 my_mem = load_node;
3044 } else {
3045 assert(my_mem->unique_out() == this, "sanity");
3046 del_req(Precedent);
3047 phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later
3048 my_mem = NULL;
3049 }
3050 }
3051 if (my_mem != NULL && my_mem->is_Mem()) {
3052 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
3053 // Check for scalar replaced object reference.
3054 if( t_oop != NULL && t_oop->is_known_instance_field() &&
3055 t_oop->offset() != Type::OffsetBot &&
3056 t_oop->offset() != Type::OffsetTop) {
3057 eliminate = true;
3058 }
3059 }
3060 } else if (opc == Op_MemBarRelease) {
3061 // Final field stores.
3062 Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent), phase);
3063 if ((alloc != NULL) && alloc->is_Allocate() &&
3064 alloc->as_Allocate()->_is_non_escaping) {
3065 // The allocated object does not escape.
3066 eliminate = true;
3067 }
3068 }
3069 if (eliminate) {
3070 // Replace MemBar projections by its inputs.
3071 PhaseIterGVN* igvn = phase->is_IterGVN();
3072 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
3073 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
3074 // Must return either the original node (now dead) or a new node
3075 // (Do not return a top here, since that would break the uniqueness of top.)
3076 return new (phase->C) ConINode(TypeInt::ZERO);
3077 }
3078 }
3079 return NULL;
3080 }
3081
3082 //------------------------------Value------------------------------------------
3083 const Type *MemBarNode::Value( PhaseTransform *phase ) const {
3084 if( !in(0) ) return Type::TOP;
3085 if( phase->type(in(0)) == Type::TOP )
3086 return Type::TOP;
3087 return TypeTuple::MEMBAR;
3088 }
3089
3090 //------------------------------match------------------------------------------
3091 // Construct projections for memory.
3092 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) {
3093 switch (proj->_con) {
3094 case TypeFunc::Control:
3095 case TypeFunc::Memory:
3096 return new (m->C) MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
3097 }
3098 ShouldNotReachHere();
3099 return NULL;
3100 }
3101
3102 //===========================InitializeNode====================================
3103 // SUMMARY:
3104 // This node acts as a memory barrier on raw memory, after some raw stores.
3105 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
3106 // The Initialize can 'capture' suitably constrained stores as raw inits.
3107 // It can coalesce related raw stores into larger units (called 'tiles').
3108 // It can avoid zeroing new storage for memory units which have raw inits.
3109 // At macro-expansion, it is marked 'complete', and does not optimize further.
3110 //
3111 // EXAMPLE:
3112 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
3113 // ctl = incoming control; mem* = incoming memory
3114 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
3115 // First allocate uninitialized memory and fill in the header:
3116 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
3117 // ctl := alloc.Control; mem* := alloc.Memory*
3118 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
3119 // Then initialize to zero the non-header parts of the raw memory block:
3120 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
3121 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
3122 // After the initialize node executes, the object is ready for service:
3123 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
3124 // Suppose its body is immediately initialized as {1,2}:
3125 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3126 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3127 // mem.SLICE(#short[*]) := store2
3128 //
3129 // DETAILS:
3130 // An InitializeNode collects and isolates object initialization after
3131 // an AllocateNode and before the next possible safepoint. As a
3132 // memory barrier (MemBarNode), it keeps critical stores from drifting
3133 // down past any safepoint or any publication of the allocation.
3134 // Before this barrier, a newly-allocated object may have uninitialized bits.
3135 // After this barrier, it may be treated as a real oop, and GC is allowed.
3136 //
3137 // The semantics of the InitializeNode include an implicit zeroing of
3138 // the new object from object header to the end of the object.
3139 // (The object header and end are determined by the AllocateNode.)
3140 //
3141 // Certain stores may be added as direct inputs to the InitializeNode.
3142 // These stores must update raw memory, and they must be to addresses
3143 // derived from the raw address produced by AllocateNode, and with
3144 // a constant offset. They must be ordered by increasing offset.
3145 // The first one is at in(RawStores), the last at in(req()-1).
3146 // Unlike most memory operations, they are not linked in a chain,
3147 // but are displayed in parallel as users of the rawmem output of
3148 // the allocation.
3149 //
3150 // (See comments in InitializeNode::capture_store, which continue
3151 // the example given above.)
3152 //
3153 // When the associated Allocate is macro-expanded, the InitializeNode
3154 // may be rewritten to optimize collected stores. A ClearArrayNode
3155 // may also be created at that point to represent any required zeroing.
3156 // The InitializeNode is then marked 'complete', prohibiting further
3157 // capturing of nearby memory operations.
3158 //
3159 // During macro-expansion, all captured initializations which store
3160 // constant values of 32 bits or smaller are coalesced (if advantageous)
3161 // into larger 'tiles' 32 or 64 bits. This allows an object to be
3162 // initialized in fewer memory operations. Memory words which are
3163 // covered by neither tiles nor non-constant stores are pre-zeroed
3164 // by explicit stores of zero. (The code shape happens to do all
3165 // zeroing first, then all other stores, with both sequences occurring
3166 // in order of ascending offsets.)
3167 //
3168 // Alternatively, code may be inserted between an AllocateNode and its
3169 // InitializeNode, to perform arbitrary initialization of the new object.
3170 // E.g., the object copying intrinsics insert complex data transfers here.
3171 // The initialization must then be marked as 'complete' disable the
3172 // built-in zeroing semantics and the collection of initializing stores.
3173 //
3174 // While an InitializeNode is incomplete, reads from the memory state
3175 // produced by it are optimizable if they match the control edge and
3176 // new oop address associated with the allocation/initialization.
3177 // They return a stored value (if the offset matches) or else zero.
3178 // A write to the memory state, if it matches control and address,
3179 // and if it is to a constant offset, may be 'captured' by the
3180 // InitializeNode. It is cloned as a raw memory operation and rewired
3181 // inside the initialization, to the raw oop produced by the allocation.
3182 // Operations on addresses which are provably distinct (e.g., to
3183 // other AllocateNodes) are allowed to bypass the initialization.
3184 //
3185 // The effect of all this is to consolidate object initialization
3186 // (both arrays and non-arrays, both piecewise and bulk) into a
3187 // single location, where it can be optimized as a unit.
3188 //
3189 // Only stores with an offset less than TrackedInitializationLimit words
3190 // will be considered for capture by an InitializeNode. This puts a
3191 // reasonable limit on the complexity of optimized initializations.
3192
3193 //---------------------------InitializeNode------------------------------------
3194 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
3195 : _is_complete(Incomplete), _does_not_escape(false),
3196 MemBarNode(C, adr_type, rawoop)
3197 {
3198 init_class_id(Class_Initialize);
3199
3200 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
3201 assert(in(RawAddress) == rawoop, "proper init");
3202 // Note: allocation() can be NULL, for secondary initialization barriers
3203 }
3204
3205 // Since this node is not matched, it will be processed by the
3206 // register allocator. Declare that there are no constraints
3207 // on the allocation of the RawAddress edge.
3208 const RegMask &InitializeNode::in_RegMask(uint idx) const {
3209 // This edge should be set to top, by the set_complete. But be conservative.
3210 if (idx == InitializeNode::RawAddress)
3211 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
3212 return RegMask::Empty;
3213 }
3214
3215 Node* InitializeNode::memory(uint alias_idx) {
3216 Node* mem = in(Memory);
3217 if (mem->is_MergeMem()) {
3218 return mem->as_MergeMem()->memory_at(alias_idx);
3219 } else {
3220 // incoming raw memory is not split
3221 return mem;
3222 }
3223 }
3224
3225 bool InitializeNode::is_non_zero() {
3226 if (is_complete()) return false;
3227 remove_extra_zeroes();
3228 return (req() > RawStores);
3229 }
3230
3231 void InitializeNode::set_complete(PhaseGVN* phase) {
3232 assert(!is_complete(), "caller responsibility");
3233 _is_complete = Complete;
3234
3235 // After this node is complete, it contains a bunch of
3236 // raw-memory initializations. There is no need for
3237 // it to have anything to do with non-raw memory effects.
3238 // Therefore, tell all non-raw users to re-optimize themselves,
3239 // after skipping the memory effects of this initialization.
3240 PhaseIterGVN* igvn = phase->is_IterGVN();
3241 if (igvn) igvn->add_users_to_worklist(this);
3242 }
3243
3244 // convenience function
3245 // return false if the init contains any stores already
3246 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
3247 InitializeNode* init = initialization();
3248 if (init == NULL || init->is_complete()) return false;
3249 init->remove_extra_zeroes();
3250 // for now, if this allocation has already collected any inits, bail:
3251 if (init->is_non_zero()) return false;
3252 init->set_complete(phase);
3253 return true;
3254 }
3255
3256 void InitializeNode::remove_extra_zeroes() {
3257 if (req() == RawStores) return;
3258 Node* zmem = zero_memory();
3259 uint fill = RawStores;
3260 for (uint i = fill; i < req(); i++) {
3261 Node* n = in(i);
3262 if (n->is_top() || n == zmem) continue; // skip
3263 if (fill < i) set_req(fill, n); // compact
3264 ++fill;
3265 }
3266 // delete any empty spaces created:
3267 while (fill < req()) {
3268 del_req(fill);
3269 }
3270 }
3271
3272 // Helper for remembering which stores go with which offsets.
3273 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) {
3274 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
3275 intptr_t offset = -1;
3276 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
3277 phase, offset);
3278 if (base == NULL) return -1; // something is dead,
3279 if (offset < 0) return -1; // dead, dead
3280 return offset;
3281 }
3282
3283 // Helper for proving that an initialization expression is
3284 // "simple enough" to be folded into an object initialization.
3285 // Attempts to prove that a store's initial value 'n' can be captured
3286 // within the initialization without creating a vicious cycle, such as:
3287 // { Foo p = new Foo(); p.next = p; }
3288 // True for constants and parameters and small combinations thereof.
3289 bool InitializeNode::detect_init_independence(Node* n, int& count) {
3290 if (n == NULL) return true; // (can this really happen?)
3291 if (n->is_Proj()) n = n->in(0);
3292 if (n == this) return false; // found a cycle
3293 if (n->is_Con()) return true;
3294 if (n->is_Start()) return true; // params, etc., are OK
3295 if (n->is_Root()) return true; // even better
3296
3297 Node* ctl = n->in(0);
3298 if (ctl != NULL && !ctl->is_top()) {
3299 if (ctl->is_Proj()) ctl = ctl->in(0);
3300 if (ctl == this) return false;
3301
3302 // If we already know that the enclosing memory op is pinned right after
3303 // the init, then any control flow that the store has picked up
3304 // must have preceded the init, or else be equal to the init.
3305 // Even after loop optimizations (which might change control edges)
3306 // a store is never pinned *before* the availability of its inputs.
3307 if (!MemNode::all_controls_dominate(n, this))
3308 return false; // failed to prove a good control
3309 }
3310
3311 // Check data edges for possible dependencies on 'this'.
3312 if ((count += 1) > 20) return false; // complexity limit
3313 for (uint i = 1; i < n->req(); i++) {
3314 Node* m = n->in(i);
3315 if (m == NULL || m == n || m->is_top()) continue;
3316 uint first_i = n->find_edge(m);
3317 if (i != first_i) continue; // process duplicate edge just once
3318 if (!detect_init_independence(m, count)) {
3319 return false;
3320 }
3321 }
3322
3323 return true;
3324 }
3325
3326 // Here are all the checks a Store must pass before it can be moved into
3327 // an initialization. Returns zero if a check fails.
3328 // On success, returns the (constant) offset to which the store applies,
3329 // within the initialized memory.
3330 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase, bool can_reshape) {
3331 const int FAIL = 0;
3332 if (st->is_unaligned_access()) {
3333 return FAIL;
3334 }
3335 if (st->req() != MemNode::ValueIn + 1)
3336 return FAIL; // an inscrutable StoreNode (card mark?)
3337 Node* ctl = st->in(MemNode::Control);
3338 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this))
3339 return FAIL; // must be unconditional after the initialization
3340 Node* mem = st->in(MemNode::Memory);
3341 if (!(mem->is_Proj() && mem->in(0) == this))
3342 return FAIL; // must not be preceded by other stores
3343 Node* adr = st->in(MemNode::Address);
3344 intptr_t offset;
3345 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
3346 if (alloc == NULL)
3347 return FAIL; // inscrutable address
3348 if (alloc != allocation())
3349 return FAIL; // wrong allocation! (store needs to float up)
3350 Node* val = st->in(MemNode::ValueIn);
3351 int complexity_count = 0;
3352 if (!detect_init_independence(val, complexity_count))
3353 return FAIL; // stored value must be 'simple enough'
3354
3355 // The Store can be captured only if nothing after the allocation
3356 // and before the Store is using the memory location that the store
3357 // overwrites.
3358 bool failed = false;
3359 // If is_complete_with_arraycopy() is true the shape of the graph is
3360 // well defined and is safe so no need for extra checks.
3361 if (!is_complete_with_arraycopy()) {
3362 // We are going to look at each use of the memory state following
3363 // the allocation to make sure nothing reads the memory that the
3364 // Store writes.
3365 const TypePtr* t_adr = phase->type(adr)->isa_ptr();
3366 int alias_idx = phase->C->get_alias_index(t_adr);
3367 ResourceMark rm;
3368 Unique_Node_List mems;
3369 mems.push(mem);
3370 Node* unique_merge = NULL;
3371 for (uint next = 0; next < mems.size(); ++next) {
3372 Node *m = mems.at(next);
3373 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
3374 Node *n = m->fast_out(j);
3375 if (n->outcnt() == 0) {
3376 continue;
3377 }
3378 if (n == st) {
3379 continue;
3380 } else if (n->in(0) != NULL && n->in(0) != ctl) {
3381 // If the control of this use is different from the control
3382 // of the Store which is right after the InitializeNode then
3383 // this node cannot be between the InitializeNode and the
3384 // Store.
3385 continue;
3386 } else if (n->is_MergeMem()) {
3387 if (n->as_MergeMem()->memory_at(alias_idx) == m) {
3388 // We can hit a MergeMemNode (that will likely go away
3389 // later) that is a direct use of the memory state
3390 // following the InitializeNode on the same slice as the
3391 // store node that we'd like to capture. We need to check
3392 // the uses of the MergeMemNode.
3393 mems.push(n);
3394 }
3395 } else if (n->is_Mem()) {
3396 Node* other_adr = n->in(MemNode::Address);
3397 if (other_adr == adr) {
3398 failed = true;
3399 break;
3400 } else {
3401 const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr();
3402 if (other_t_adr != NULL) {
3403 int other_alias_idx = phase->C->get_alias_index(other_t_adr);
3404 if (other_alias_idx == alias_idx) {
3405 // A load from the same memory slice as the store right
3406 // after the InitializeNode. We check the control of the
3407 // object/array that is loaded from. If it's the same as
3408 // the store control then we cannot capture the store.
3409 assert(!n->is_Store(), "2 stores to same slice on same control?");
3410 Node* base = other_adr;
3411 assert(base->is_AddP(), err_msg_res("should be addp but is %s", base->Name()));
3412 base = base->in(AddPNode::Base);
3413 if (base != NULL) {
3414 base = base->uncast();
3415 if (base->is_Proj() && base->in(0) == alloc) {
3416 failed = true;
3417 break;
3418 }
3419 }
3420 }
3421 }
3422 }
3423 } else {
3424 failed = true;
3425 break;
3426 }
3427 }
3428 }
3429 }
3430 if (failed) {
3431 if (!can_reshape) {
3432 // We decided we couldn't capture the store during parsing. We
3433 // should try again during the next IGVN once the graph is
3434 // cleaner.
3435 phase->C->record_for_igvn(st);
3436 }
3437 return FAIL;
3438 }
3439
3440 return offset; // success
3441 }
3442
3443 // Find the captured store in(i) which corresponds to the range
3444 // [start..start+size) in the initialized object.
3445 // If there is one, return its index i. If there isn't, return the
3446 // negative of the index where it should be inserted.
3447 // Return 0 if the queried range overlaps an initialization boundary
3448 // or if dead code is encountered.
3449 // If size_in_bytes is zero, do not bother with overlap checks.
3450 int InitializeNode::captured_store_insertion_point(intptr_t start,
3451 int size_in_bytes,
3452 PhaseTransform* phase) {
3453 const int FAIL = 0, MAX_STORE = BytesPerLong;
3454
3455 if (is_complete())
3456 return FAIL; // arraycopy got here first; punt
3457
3458 assert(allocation() != NULL, "must be present");
3459
3460 // no negatives, no header fields:
3461 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
3462
3463 // after a certain size, we bail out on tracking all the stores:
3464 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3465 if (start >= ti_limit) return FAIL;
3466
3467 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
3468 if (i >= limit) return -(int)i; // not found; here is where to put it
3469
3470 Node* st = in(i);
3471 intptr_t st_off = get_store_offset(st, phase);
3472 if (st_off < 0) {
3473 if (st != zero_memory()) {
3474 return FAIL; // bail out if there is dead garbage
3475 }
3476 } else if (st_off > start) {
3477 // ...we are done, since stores are ordered
3478 if (st_off < start + size_in_bytes) {
3479 return FAIL; // the next store overlaps
3480 }
3481 return -(int)i; // not found; here is where to put it
3482 } else if (st_off < start) {
3483 if (size_in_bytes != 0 &&
3484 start < st_off + MAX_STORE &&
3485 start < st_off + st->as_Store()->memory_size()) {
3486 return FAIL; // the previous store overlaps
3487 }
3488 } else {
3489 if (size_in_bytes != 0 &&
3490 st->as_Store()->memory_size() != size_in_bytes) {
3491 return FAIL; // mismatched store size
3492 }
3493 return i;
3494 }
3495
3496 ++i;
3497 }
3498 }
3499
3500 // Look for a captured store which initializes at the offset 'start'
3501 // with the given size. If there is no such store, and no other
3502 // initialization interferes, then return zero_memory (the memory
3503 // projection of the AllocateNode).
3504 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
3505 PhaseTransform* phase) {
3506 assert(stores_are_sane(phase), "");
3507 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3508 if (i == 0) {
3509 return NULL; // something is dead
3510 } else if (i < 0) {
3511 return zero_memory(); // just primordial zero bits here
3512 } else {
3513 Node* st = in(i); // here is the store at this position
3514 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
3515 return st;
3516 }
3517 }
3518
3519 // Create, as a raw pointer, an address within my new object at 'offset'.
3520 Node* InitializeNode::make_raw_address(intptr_t offset,
3521 PhaseTransform* phase) {
3522 Node* addr = in(RawAddress);
3523 if (offset != 0) {
3524 Compile* C = phase->C;
3525 addr = phase->transform( new (C) AddPNode(C->top(), addr,
3526 phase->MakeConX(offset)) );
3527 }
3528 return addr;
3529 }
3530
3531 // Clone the given store, converting it into a raw store
3532 // initializing a field or element of my new object.
3533 // Caller is responsible for retiring the original store,
3534 // with subsume_node or the like.
3535 //
3536 // From the example above InitializeNode::InitializeNode,
3537 // here are the old stores to be captured:
3538 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3539 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3540 //
3541 // Here is the changed code; note the extra edges on init:
3542 // alloc = (Allocate ...)
3543 // rawoop = alloc.RawAddress
3544 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
3545 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
3546 // init = (Initialize alloc.Control alloc.Memory rawoop
3547 // rawstore1 rawstore2)
3548 //
3549 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
3550 PhaseTransform* phase, bool can_reshape) {
3551 assert(stores_are_sane(phase), "");
3552
3553 if (start < 0) return NULL;
3554 assert(can_capture_store(st, phase, can_reshape) == start, "sanity");
3555
3556 Compile* C = phase->C;
3557 int size_in_bytes = st->memory_size();
3558 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3559 if (i == 0) return NULL; // bail out
3560 Node* prev_mem = NULL; // raw memory for the captured store
3561 if (i > 0) {
3562 prev_mem = in(i); // there is a pre-existing store under this one
3563 set_req(i, C->top()); // temporarily disconnect it
3564 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
3565 } else {
3566 i = -i; // no pre-existing store
3567 prev_mem = zero_memory(); // a slice of the newly allocated object
3568 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
3569 set_req(--i, C->top()); // reuse this edge; it has been folded away
3570 else
3571 ins_req(i, C->top()); // build a new edge
3572 }
3573 Node* new_st = st->clone();
3574 new_st->set_req(MemNode::Control, in(Control));
3575 new_st->set_req(MemNode::Memory, prev_mem);
3576 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
3577 new_st = phase->transform(new_st);
3578
3579 // At this point, new_st might have swallowed a pre-existing store
3580 // at the same offset, or perhaps new_st might have disappeared,
3581 // if it redundantly stored the same value (or zero to fresh memory).
3582
3583 // In any case, wire it in:
3584 set_req(i, new_st);
3585
3586 // The caller may now kill the old guy.
3587 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
3588 assert(check_st == new_st || check_st == NULL, "must be findable");
3589 assert(!is_complete(), "");
3590 return new_st;
3591 }
3592
3593 static bool store_constant(jlong* tiles, int num_tiles,
3594 intptr_t st_off, int st_size,
3595 jlong con) {
3596 if ((st_off & (st_size-1)) != 0)
3597 return false; // strange store offset (assume size==2**N)
3598 address addr = (address)tiles + st_off;
3599 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
3600 switch (st_size) {
3601 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
3602 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
3603 case sizeof(jint): *(jint*) addr = (jint) con; break;
3604 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
3605 default: return false; // strange store size (detect size!=2**N here)
3606 }
3607 return true; // return success to caller
3608 }
3609
3610 // Coalesce subword constants into int constants and possibly
3611 // into long constants. The goal, if the CPU permits,
3612 // is to initialize the object with a small number of 64-bit tiles.
3613 // Also, convert floating-point constants to bit patterns.
3614 // Non-constants are not relevant to this pass.
3615 //
3616 // In terms of the running example on InitializeNode::InitializeNode
3617 // and InitializeNode::capture_store, here is the transformation
3618 // of rawstore1 and rawstore2 into rawstore12:
3619 // alloc = (Allocate ...)
3620 // rawoop = alloc.RawAddress
3621 // tile12 = 0x00010002
3622 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
3623 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
3624 //
3625 void
3626 InitializeNode::coalesce_subword_stores(intptr_t header_size,
3627 Node* size_in_bytes,
3628 PhaseGVN* phase) {
3629 Compile* C = phase->C;
3630
3631 assert(stores_are_sane(phase), "");
3632 // Note: After this pass, they are not completely sane,
3633 // since there may be some overlaps.
3634
3635 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
3636
3637 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3638 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
3639 size_limit = MIN2(size_limit, ti_limit);
3640 size_limit = align_size_up(size_limit, BytesPerLong);
3641 int num_tiles = size_limit / BytesPerLong;
3642
3643 // allocate space for the tile map:
3644 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
3645 jlong tiles_buf[small_len];
3646 Node* nodes_buf[small_len];
3647 jlong inits_buf[small_len];
3648 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
3649 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3650 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
3651 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
3652 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
3653 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3654 // tiles: exact bitwise model of all primitive constants
3655 // nodes: last constant-storing node subsumed into the tiles model
3656 // inits: which bytes (in each tile) are touched by any initializations
3657
3658 //// Pass A: Fill in the tile model with any relevant stores.
3659
3660 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
3661 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
3662 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
3663 Node* zmem = zero_memory(); // initially zero memory state
3664 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3665 Node* st = in(i);
3666 intptr_t st_off = get_store_offset(st, phase);
3667
3668 // Figure out the store's offset and constant value:
3669 if (st_off < header_size) continue; //skip (ignore header)
3670 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
3671 int st_size = st->as_Store()->memory_size();
3672 if (st_off + st_size > size_limit) break;
3673
3674 // Record which bytes are touched, whether by constant or not.
3675 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
3676 continue; // skip (strange store size)
3677
3678 const Type* val = phase->type(st->in(MemNode::ValueIn));
3679 if (!val->singleton()) continue; //skip (non-con store)
3680 BasicType type = val->basic_type();
3681
3682 jlong con = 0;
3683 switch (type) {
3684 case T_INT: con = val->is_int()->get_con(); break;
3685 case T_LONG: con = val->is_long()->get_con(); break;
3686 case T_FLOAT: con = jint_cast(val->getf()); break;
3687 case T_DOUBLE: con = jlong_cast(val->getd()); break;
3688 default: continue; //skip (odd store type)
3689 }
3690
3691 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
3692 st->Opcode() == Op_StoreL) {
3693 continue; // This StoreL is already optimal.
3694 }
3695
3696 // Store down the constant.
3697 store_constant(tiles, num_tiles, st_off, st_size, con);
3698
3699 intptr_t j = st_off >> LogBytesPerLong;
3700
3701 if (type == T_INT && st_size == BytesPerInt
3702 && (st_off & BytesPerInt) == BytesPerInt) {
3703 jlong lcon = tiles[j];
3704 if (!Matcher::isSimpleConstant64(lcon) &&
3705 st->Opcode() == Op_StoreI) {
3706 // This StoreI is already optimal by itself.
3707 jint* intcon = (jint*) &tiles[j];
3708 intcon[1] = 0; // undo the store_constant()
3709
3710 // If the previous store is also optimal by itself, back up and
3711 // undo the action of the previous loop iteration... if we can.
3712 // But if we can't, just let the previous half take care of itself.
3713 st = nodes[j];
3714 st_off -= BytesPerInt;
3715 con = intcon[0];
3716 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) {
3717 assert(st_off >= header_size, "still ignoring header");
3718 assert(get_store_offset(st, phase) == st_off, "must be");
3719 assert(in(i-1) == zmem, "must be");
3720 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
3721 assert(con == tcon->is_int()->get_con(), "must be");
3722 // Undo the effects of the previous loop trip, which swallowed st:
3723 intcon[0] = 0; // undo store_constant()
3724 set_req(i-1, st); // undo set_req(i, zmem)
3725 nodes[j] = NULL; // undo nodes[j] = st
3726 --old_subword; // undo ++old_subword
3727 }
3728 continue; // This StoreI is already optimal.
3729 }
3730 }
3731
3732 // This store is not needed.
3733 set_req(i, zmem);
3734 nodes[j] = st; // record for the moment
3735 if (st_size < BytesPerLong) // something has changed
3736 ++old_subword; // includes int/float, but who's counting...
3737 else ++old_long;
3738 }
3739
3740 if ((old_subword + old_long) == 0)
3741 return; // nothing more to do
3742
3743 //// Pass B: Convert any non-zero tiles into optimal constant stores.
3744 // Be sure to insert them before overlapping non-constant stores.
3745 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
3746 for (int j = 0; j < num_tiles; j++) {
3747 jlong con = tiles[j];
3748 jlong init = inits[j];
3749 if (con == 0) continue;
3750 jint con0, con1; // split the constant, address-wise
3751 jint init0, init1; // split the init map, address-wise
3752 { union { jlong con; jint intcon[2]; } u;
3753 u.con = con;
3754 con0 = u.intcon[0];
3755 con1 = u.intcon[1];
3756 u.con = init;
3757 init0 = u.intcon[0];
3758 init1 = u.intcon[1];
3759 }
3760
3761 Node* old = nodes[j];
3762 assert(old != NULL, "need the prior store");
3763 intptr_t offset = (j * BytesPerLong);
3764
3765 bool split = !Matcher::isSimpleConstant64(con);
3766
3767 if (offset < header_size) {
3768 assert(offset + BytesPerInt >= header_size, "second int counts");
3769 assert(*(jint*)&tiles[j] == 0, "junk in header");
3770 split = true; // only the second word counts
3771 // Example: int a[] = { 42 ... }
3772 } else if (con0 == 0 && init0 == -1) {
3773 split = true; // first word is covered by full inits
3774 // Example: int a[] = { ... foo(), 42 ... }
3775 } else if (con1 == 0 && init1 == -1) {
3776 split = true; // second word is covered by full inits
3777 // Example: int a[] = { ... 42, foo() ... }
3778 }
3779
3780 // Here's a case where init0 is neither 0 nor -1:
3781 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
3782 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
3783 // In this case the tile is not split; it is (jlong)42.
3784 // The big tile is stored down, and then the foo() value is inserted.
3785 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
3786
3787 Node* ctl = old->in(MemNode::Control);
3788 Node* adr = make_raw_address(offset, phase);
3789 const TypePtr* atp = TypeRawPtr::BOTTOM;
3790
3791 // One or two coalesced stores to plop down.
3792 Node* st[2];
3793 intptr_t off[2];
3794 int nst = 0;
3795 if (!split) {
3796 ++new_long;
3797 off[nst] = offset;
3798 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3799 phase->longcon(con), T_LONG, MemNode::unordered);
3800 } else {
3801 // Omit either if it is a zero.
3802 if (con0 != 0) {
3803 ++new_int;
3804 off[nst] = offset;
3805 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3806 phase->intcon(con0), T_INT, MemNode::unordered);
3807 }
3808 if (con1 != 0) {
3809 ++new_int;
3810 offset += BytesPerInt;
3811 adr = make_raw_address(offset, phase);
3812 off[nst] = offset;
3813 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3814 phase->intcon(con1), T_INT, MemNode::unordered);
3815 }
3816 }
3817
3818 // Insert second store first, then the first before the second.
3819 // Insert each one just before any overlapping non-constant stores.
3820 while (nst > 0) {
3821 Node* st1 = st[--nst];
3822 C->copy_node_notes_to(st1, old);
3823 st1 = phase->transform(st1);
3824 offset = off[nst];
3825 assert(offset >= header_size, "do not smash header");
3826 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
3827 guarantee(ins_idx != 0, "must re-insert constant store");
3828 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
3829 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
3830 set_req(--ins_idx, st1);
3831 else
3832 ins_req(ins_idx, st1);
3833 }
3834 }
3835
3836 if (PrintCompilation && WizardMode)
3837 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
3838 old_subword, old_long, new_int, new_long);
3839 if (C->log() != NULL)
3840 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
3841 old_subword, old_long, new_int, new_long);
3842
3843 // Clean up any remaining occurrences of zmem:
3844 remove_extra_zeroes();
3845 }
3846
3847 // Explore forward from in(start) to find the first fully initialized
3848 // word, and return its offset. Skip groups of subword stores which
3849 // together initialize full words. If in(start) is itself part of a
3850 // fully initialized word, return the offset of in(start). If there
3851 // are no following full-word stores, or if something is fishy, return
3852 // a negative value.
3853 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
3854 int int_map = 0;
3855 intptr_t int_map_off = 0;
3856 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
3857
3858 for (uint i = start, limit = req(); i < limit; i++) {
3859 Node* st = in(i);
3860
3861 intptr_t st_off = get_store_offset(st, phase);
3862 if (st_off < 0) break; // return conservative answer
3863
3864 int st_size = st->as_Store()->memory_size();
3865 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
3866 return st_off; // we found a complete word init
3867 }
3868
3869 // update the map:
3870
3871 intptr_t this_int_off = align_size_down(st_off, BytesPerInt);
3872 if (this_int_off != int_map_off) {
3873 // reset the map:
3874 int_map = 0;
3875 int_map_off = this_int_off;
3876 }
3877
3878 int subword_off = st_off - this_int_off;
3879 int_map |= right_n_bits(st_size) << subword_off;
3880 if ((int_map & FULL_MAP) == FULL_MAP) {
3881 return this_int_off; // we found a complete word init
3882 }
3883
3884 // Did this store hit or cross the word boundary?
3885 intptr_t next_int_off = align_size_down(st_off + st_size, BytesPerInt);
3886 if (next_int_off == this_int_off + BytesPerInt) {
3887 // We passed the current int, without fully initializing it.
3888 int_map_off = next_int_off;
3889 int_map >>= BytesPerInt;
3890 } else if (next_int_off > this_int_off + BytesPerInt) {
3891 // We passed the current and next int.
3892 return this_int_off + BytesPerInt;
3893 }
3894 }
3895
3896 return -1;
3897 }
3898
3899
3900 // Called when the associated AllocateNode is expanded into CFG.
3901 // At this point, we may perform additional optimizations.
3902 // Linearize the stores by ascending offset, to make memory
3903 // activity as coherent as possible.
3904 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
3905 intptr_t header_size,
3906 Node* size_in_bytes,
3907 PhaseGVN* phase) {
3908 assert(!is_complete(), "not already complete");
3909 assert(stores_are_sane(phase), "");
3910 assert(allocation() != NULL, "must be present");
3911
3912 remove_extra_zeroes();
3913
3914 if (ReduceFieldZeroing || ReduceBulkZeroing)
3915 // reduce instruction count for common initialization patterns
3916 coalesce_subword_stores(header_size, size_in_bytes, phase);
3917
3918 Node* zmem = zero_memory(); // initially zero memory state
3919 Node* inits = zmem; // accumulating a linearized chain of inits
3920 #ifdef ASSERT
3921 intptr_t first_offset = allocation()->minimum_header_size();
3922 intptr_t last_init_off = first_offset; // previous init offset
3923 intptr_t last_init_end = first_offset; // previous init offset+size
3924 intptr_t last_tile_end = first_offset; // previous tile offset+size
3925 #endif
3926 intptr_t zeroes_done = header_size;
3927
3928 bool do_zeroing = true; // we might give up if inits are very sparse
3929 int big_init_gaps = 0; // how many large gaps have we seen?
3930
3931 if (ZeroTLAB) do_zeroing = false;
3932 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
3933
3934 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3935 Node* st = in(i);
3936 intptr_t st_off = get_store_offset(st, phase);
3937 if (st_off < 0)
3938 break; // unknown junk in the inits
3939 if (st->in(MemNode::Memory) != zmem)
3940 break; // complicated store chains somehow in list
3941
3942 int st_size = st->as_Store()->memory_size();
3943 intptr_t next_init_off = st_off + st_size;
3944
3945 if (do_zeroing && zeroes_done < next_init_off) {
3946 // See if this store needs a zero before it or under it.
3947 intptr_t zeroes_needed = st_off;
3948
3949 if (st_size < BytesPerInt) {
3950 // Look for subword stores which only partially initialize words.
3951 // If we find some, we must lay down some word-level zeroes first,
3952 // underneath the subword stores.
3953 //
3954 // Examples:
3955 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
3956 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
3957 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
3958 //
3959 // Note: coalesce_subword_stores may have already done this,
3960 // if it was prompted by constant non-zero subword initializers.
3961 // But this case can still arise with non-constant stores.
3962
3963 intptr_t next_full_store = find_next_fullword_store(i, phase);
3964
3965 // In the examples above:
3966 // in(i) p q r s x y z
3967 // st_off 12 13 14 15 12 13 14
3968 // st_size 1 1 1 1 1 1 1
3969 // next_full_s. 12 16 16 16 16 16 16
3970 // z's_done 12 16 16 16 12 16 12
3971 // z's_needed 12 16 16 16 16 16 16
3972 // zsize 0 0 0 0 4 0 4
3973 if (next_full_store < 0) {
3974 // Conservative tack: Zero to end of current word.
3975 zeroes_needed = align_size_up(zeroes_needed, BytesPerInt);
3976 } else {
3977 // Zero to beginning of next fully initialized word.
3978 // Or, don't zero at all, if we are already in that word.
3979 assert(next_full_store >= zeroes_needed, "must go forward");
3980 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
3981 zeroes_needed = next_full_store;
3982 }
3983 }
3984
3985 if (zeroes_needed > zeroes_done) {
3986 intptr_t zsize = zeroes_needed - zeroes_done;
3987 // Do some incremental zeroing on rawmem, in parallel with inits.
3988 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3989 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3990 zeroes_done, zeroes_needed,
3991 phase);
3992 zeroes_done = zeroes_needed;
3993 if (zsize > Matcher::init_array_short_size && ++big_init_gaps > 2)
3994 do_zeroing = false; // leave the hole, next time
3995 }
3996 }
3997
3998 // Collect the store and move on:
3999 st->set_req(MemNode::Memory, inits);
4000 inits = st; // put it on the linearized chain
4001 set_req(i, zmem); // unhook from previous position
4002
4003 if (zeroes_done == st_off)
4004 zeroes_done = next_init_off;
4005
4006 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
4007
4008 #ifdef ASSERT
4009 // Various order invariants. Weaker than stores_are_sane because
4010 // a large constant tile can be filled in by smaller non-constant stores.
4011 assert(st_off >= last_init_off, "inits do not reverse");
4012 last_init_off = st_off;
4013 const Type* val = NULL;
4014 if (st_size >= BytesPerInt &&
4015 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
4016 (int)val->basic_type() < (int)T_OBJECT) {
4017 assert(st_off >= last_tile_end, "tiles do not overlap");
4018 assert(st_off >= last_init_end, "tiles do not overwrite inits");
4019 last_tile_end = MAX2(last_tile_end, next_init_off);
4020 } else {
4021 intptr_t st_tile_end = align_size_up(next_init_off, BytesPerLong);
4022 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
4023 assert(st_off >= last_init_end, "inits do not overlap");
4024 last_init_end = next_init_off; // it's a non-tile
4025 }
4026 #endif //ASSERT
4027 }
4028
4029 remove_extra_zeroes(); // clear out all the zmems left over
4030 add_req(inits);
4031
4032 if (!ZeroTLAB) {
4033 // If anything remains to be zeroed, zero it all now.
4034 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
4035 // if it is the last unused 4 bytes of an instance, forget about it
4036 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
4037 if (zeroes_done + BytesPerLong >= size_limit) {
4038 assert(allocation() != NULL, "");
4039 if (allocation()->Opcode() == Op_Allocate) {
4040 Node* klass_node = allocation()->in(AllocateNode::KlassNode);
4041 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass();
4042 if (zeroes_done == k->layout_helper())
4043 zeroes_done = size_limit;
4044 }
4045 }
4046 if (zeroes_done < size_limit) {
4047 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
4048 zeroes_done, size_in_bytes, phase);
4049 }
4050 }
4051
4052 set_complete(phase);
4053 return rawmem;
4054 }
4055
4056
4057 #ifdef ASSERT
4058 bool InitializeNode::stores_are_sane(PhaseTransform* phase) {
4059 if (is_complete())
4060 return true; // stores could be anything at this point
4061 assert(allocation() != NULL, "must be present");
4062 intptr_t last_off = allocation()->minimum_header_size();
4063 for (uint i = InitializeNode::RawStores; i < req(); i++) {
4064 Node* st = in(i);
4065 intptr_t st_off = get_store_offset(st, phase);
4066 if (st_off < 0) continue; // ignore dead garbage
4067 if (last_off > st_off) {
4068 tty->print_cr("*** bad store offset at %d: " INTX_FORMAT " > " INTX_FORMAT, i, last_off, st_off);
4069 this->dump(2);
4070 assert(false, "ascending store offsets");
4071 return false;
4072 }
4073 last_off = st_off + st->as_Store()->memory_size();
4074 }
4075 return true;
4076 }
4077 #endif //ASSERT
4078
4079
4080
4081
4082 //============================MergeMemNode=====================================
4083 //
4084 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
4085 // contributing store or call operations. Each contributor provides the memory
4086 // state for a particular "alias type" (see Compile::alias_type). For example,
4087 // if a MergeMem has an input X for alias category #6, then any memory reference
4088 // to alias category #6 may use X as its memory state input, as an exact equivalent
4089 // to using the MergeMem as a whole.
4090 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
4091 //
4092 // (Here, the <N> notation gives the index of the relevant adr_type.)
4093 //
4094 // In one special case (and more cases in the future), alias categories overlap.
4095 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
4096 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
4097 // it is exactly equivalent to that state W:
4098 // MergeMem(<Bot>: W) <==> W
4099 //
4100 // Usually, the merge has more than one input. In that case, where inputs
4101 // overlap (i.e., one is Bot), the narrower alias type determines the memory
4102 // state for that type, and the wider alias type (Bot) fills in everywhere else:
4103 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
4104 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
4105 //
4106 // A merge can take a "wide" memory state as one of its narrow inputs.
4107 // This simply means that the merge observes out only the relevant parts of
4108 // the wide input. That is, wide memory states arriving at narrow merge inputs
4109 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
4110 //
4111 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
4112 // and that memory slices "leak through":
4113 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
4114 //
4115 // But, in such a cascade, repeated memory slices can "block the leak":
4116 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
4117 //
4118 // In the last example, Y is not part of the combined memory state of the
4119 // outermost MergeMem. The system must, of course, prevent unschedulable
4120 // memory states from arising, so you can be sure that the state Y is somehow
4121 // a precursor to state Y'.
4122 //
4123 //
4124 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
4125 // of each MergeMemNode array are exactly the numerical alias indexes, including
4126 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
4127 // Compile::alias_type (and kin) produce and manage these indexes.
4128 //
4129 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
4130 // (Note that this provides quick access to the top node inside MergeMem methods,
4131 // without the need to reach out via TLS to Compile::current.)
4132 //
4133 // As a consequence of what was just described, a MergeMem that represents a full
4134 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
4135 // containing all alias categories.
4136 //
4137 // MergeMem nodes never (?) have control inputs, so in(0) is NULL.
4138 //
4139 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
4140 // a memory state for the alias type <N>, or else the top node, meaning that
4141 // there is no particular input for that alias type. Note that the length of
4142 // a MergeMem is variable, and may be extended at any time to accommodate new
4143 // memory states at larger alias indexes. When merges grow, they are of course
4144 // filled with "top" in the unused in() positions.
4145 //
4146 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
4147 // (Top was chosen because it works smoothly with passes like GCM.)
4148 //
4149 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
4150 // the type of random VM bits like TLS references.) Since it is always the
4151 // first non-Bot memory slice, some low-level loops use it to initialize an
4152 // index variable: for (i = AliasIdxRaw; i < req(); i++).
4153 //
4154 //
4155 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
4156 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
4157 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
4158 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
4159 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
4160 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
4161 //
4162 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
4163 // really that different from the other memory inputs. An abbreviation called
4164 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
4165 //
4166 //
4167 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
4168 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
4169 // that "emerges though" the base memory will be marked as excluding the alias types
4170 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
4171 //
4172 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
4173 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
4174 //
4175 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
4176 // (It is currently unimplemented.) As you can see, the resulting merge is
4177 // actually a disjoint union of memory states, rather than an overlay.
4178 //
4179
4180 //------------------------------MergeMemNode-----------------------------------
4181 Node* MergeMemNode::make_empty_memory() {
4182 Node* empty_memory = (Node*) Compile::current()->top();
4183 assert(empty_memory->is_top(), "correct sentinel identity");
4184 return empty_memory;
4185 }
4186
4187 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
4188 init_class_id(Class_MergeMem);
4189 // all inputs are nullified in Node::Node(int)
4190 // set_input(0, NULL); // no control input
4191
4192 // Initialize the edges uniformly to top, for starters.
4193 Node* empty_mem = make_empty_memory();
4194 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
4195 init_req(i,empty_mem);
4196 }
4197 assert(empty_memory() == empty_mem, "");
4198
4199 if( new_base != NULL && new_base->is_MergeMem() ) {
4200 MergeMemNode* mdef = new_base->as_MergeMem();
4201 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
4202 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
4203 mms.set_memory(mms.memory2());
4204 }
4205 assert(base_memory() == mdef->base_memory(), "");
4206 } else {
4207 set_base_memory(new_base);
4208 }
4209 }
4210
4211 // Make a new, untransformed MergeMem with the same base as 'mem'.
4212 // If mem is itself a MergeMem, populate the result with the same edges.
4213 MergeMemNode* MergeMemNode::make(Compile* C, Node* mem) {
4214 return new(C) MergeMemNode(mem);
4215 }
4216
4217 //------------------------------cmp--------------------------------------------
4218 uint MergeMemNode::hash() const { return NO_HASH; }
4219 uint MergeMemNode::cmp( const Node &n ) const {
4220 return (&n == this); // Always fail except on self
4221 }
4222
4223 //------------------------------Identity---------------------------------------
4224 Node* MergeMemNode::Identity(PhaseTransform *phase) {
4225 // Identity if this merge point does not record any interesting memory
4226 // disambiguations.
4227 Node* base_mem = base_memory();
4228 Node* empty_mem = empty_memory();
4229 if (base_mem != empty_mem) { // Memory path is not dead?
4230 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4231 Node* mem = in(i);
4232 if (mem != empty_mem && mem != base_mem) {
4233 return this; // Many memory splits; no change
4234 }
4235 }
4236 }
4237 return base_mem; // No memory splits; ID on the one true input
4238 }
4239
4240 //------------------------------Ideal------------------------------------------
4241 // This method is invoked recursively on chains of MergeMem nodes
4242 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4243 // Remove chain'd MergeMems
4244 //
4245 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
4246 // relative to the "in(Bot)". Since we are patching both at the same time,
4247 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
4248 // but rewrite each "in(i)" relative to the new "in(Bot)".
4249 Node *progress = NULL;
4250
4251
4252 Node* old_base = base_memory();
4253 Node* empty_mem = empty_memory();
4254 if (old_base == empty_mem)
4255 return NULL; // Dead memory path.
4256
4257 MergeMemNode* old_mbase;
4258 if (old_base != NULL && old_base->is_MergeMem())
4259 old_mbase = old_base->as_MergeMem();
4260 else
4261 old_mbase = NULL;
4262 Node* new_base = old_base;
4263
4264 // simplify stacked MergeMems in base memory
4265 if (old_mbase) new_base = old_mbase->base_memory();
4266
4267 // the base memory might contribute new slices beyond my req()
4268 if (old_mbase) grow_to_match(old_mbase);
4269
4270 // Look carefully at the base node if it is a phi.
4271 PhiNode* phi_base;
4272 if (new_base != NULL && new_base->is_Phi())
4273 phi_base = new_base->as_Phi();
4274 else
4275 phi_base = NULL;
4276
4277 Node* phi_reg = NULL;
4278 uint phi_len = (uint)-1;
4279 if (phi_base != NULL && !phi_base->is_copy()) {
4280 // do not examine phi if degraded to a copy
4281 phi_reg = phi_base->region();
4282 phi_len = phi_base->req();
4283 // see if the phi is unfinished
4284 for (uint i = 1; i < phi_len; i++) {
4285 if (phi_base->in(i) == NULL) {
4286 // incomplete phi; do not look at it yet!
4287 phi_reg = NULL;
4288 phi_len = (uint)-1;
4289 break;
4290 }
4291 }
4292 }
4293
4294 // Note: We do not call verify_sparse on entry, because inputs
4295 // can normalize to the base_memory via subsume_node or similar
4296 // mechanisms. This method repairs that damage.
4297
4298 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
4299
4300 // Look at each slice.
4301 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4302 Node* old_in = in(i);
4303 // calculate the old memory value
4304 Node* old_mem = old_in;
4305 if (old_mem == empty_mem) old_mem = old_base;
4306 assert(old_mem == memory_at(i), "");
4307
4308 // maybe update (reslice) the old memory value
4309
4310 // simplify stacked MergeMems
4311 Node* new_mem = old_mem;
4312 MergeMemNode* old_mmem;
4313 if (old_mem != NULL && old_mem->is_MergeMem())
4314 old_mmem = old_mem->as_MergeMem();
4315 else
4316 old_mmem = NULL;
4317 if (old_mmem == this) {
4318 // This can happen if loops break up and safepoints disappear.
4319 // A merge of BotPtr (default) with a RawPtr memory derived from a
4320 // safepoint can be rewritten to a merge of the same BotPtr with
4321 // the BotPtr phi coming into the loop. If that phi disappears
4322 // also, we can end up with a self-loop of the mergemem.
4323 // In general, if loops degenerate and memory effects disappear,
4324 // a mergemem can be left looking at itself. This simply means
4325 // that the mergemem's default should be used, since there is
4326 // no longer any apparent effect on this slice.
4327 // Note: If a memory slice is a MergeMem cycle, it is unreachable
4328 // from start. Update the input to TOP.
4329 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
4330 }
4331 else if (old_mmem != NULL) {
4332 new_mem = old_mmem->memory_at(i);
4333 }
4334 // else preceding memory was not a MergeMem
4335
4336 // replace equivalent phis (unfortunately, they do not GVN together)
4337 if (new_mem != NULL && new_mem != new_base &&
4338 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) {
4339 if (new_mem->is_Phi()) {
4340 PhiNode* phi_mem = new_mem->as_Phi();
4341 for (uint i = 1; i < phi_len; i++) {
4342 if (phi_base->in(i) != phi_mem->in(i)) {
4343 phi_mem = NULL;
4344 break;
4345 }
4346 }
4347 if (phi_mem != NULL) {
4348 // equivalent phi nodes; revert to the def
4349 new_mem = new_base;
4350 }
4351 }
4352 }
4353
4354 // maybe store down a new value
4355 Node* new_in = new_mem;
4356 if (new_in == new_base) new_in = empty_mem;
4357
4358 if (new_in != old_in) {
4359 // Warning: Do not combine this "if" with the previous "if"
4360 // A memory slice might have be be rewritten even if it is semantically
4361 // unchanged, if the base_memory value has changed.
4362 set_req(i, new_in);
4363 progress = this; // Report progress
4364 }
4365 }
4366
4367 if (new_base != old_base) {
4368 set_req(Compile::AliasIdxBot, new_base);
4369 // Don't use set_base_memory(new_base), because we need to update du.
4370 assert(base_memory() == new_base, "");
4371 progress = this;
4372 }
4373
4374 if( base_memory() == this ) {
4375 // a self cycle indicates this memory path is dead
4376 set_req(Compile::AliasIdxBot, empty_mem);
4377 }
4378
4379 // Resolve external cycles by calling Ideal on a MergeMem base_memory
4380 // Recursion must occur after the self cycle check above
4381 if( base_memory()->is_MergeMem() ) {
4382 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
4383 Node *m = phase->transform(new_mbase); // Rollup any cycles
4384 if( m != NULL && (m->is_top() ||
4385 m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem) ) {
4386 // propagate rollup of dead cycle to self
4387 set_req(Compile::AliasIdxBot, empty_mem);
4388 }
4389 }
4390
4391 if( base_memory() == empty_mem ) {
4392 progress = this;
4393 // Cut inputs during Parse phase only.
4394 // During Optimize phase a dead MergeMem node will be subsumed by Top.
4395 if( !can_reshape ) {
4396 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4397 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
4398 }
4399 }
4400 }
4401
4402 if( !progress && base_memory()->is_Phi() && can_reshape ) {
4403 // Check if PhiNode::Ideal's "Split phis through memory merges"
4404 // transform should be attempted. Look for this->phi->this cycle.
4405 uint merge_width = req();
4406 if (merge_width > Compile::AliasIdxRaw) {
4407 PhiNode* phi = base_memory()->as_Phi();
4408 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
4409 if (phi->in(i) == this) {
4410 phase->is_IterGVN()->_worklist.push(phi);
4411 break;
4412 }
4413 }
4414 }
4415 }
4416
4417 assert(progress || verify_sparse(), "please, no dups of base");
4418 return progress;
4419 }
4420
4421 //-------------------------set_base_memory-------------------------------------
4422 void MergeMemNode::set_base_memory(Node *new_base) {
4423 Node* empty_mem = empty_memory();
4424 set_req(Compile::AliasIdxBot, new_base);
4425 assert(memory_at(req()) == new_base, "must set default memory");
4426 // Clear out other occurrences of new_base:
4427 if (new_base != empty_mem) {
4428 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4429 if (in(i) == new_base) set_req(i, empty_mem);
4430 }
4431 }
4432 }
4433
4434 //------------------------------out_RegMask------------------------------------
4435 const RegMask &MergeMemNode::out_RegMask() const {
4436 return RegMask::Empty;
4437 }
4438
4439 //------------------------------dump_spec--------------------------------------
4440 #ifndef PRODUCT
4441 void MergeMemNode::dump_spec(outputStream *st) const {
4442 st->print(" {");
4443 Node* base_mem = base_memory();
4444 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
4445 Node* mem = memory_at(i);
4446 if (mem == base_mem) { st->print(" -"); continue; }
4447 st->print( " N%d:", mem->_idx );
4448 Compile::current()->get_adr_type(i)->dump_on(st);
4449 }
4450 st->print(" }");
4451 }
4452 #endif // !PRODUCT
4453
4454
4455 #ifdef ASSERT
4456 static bool might_be_same(Node* a, Node* b) {
4457 if (a == b) return true;
4458 if (!(a->is_Phi() || b->is_Phi())) return false;
4459 // phis shift around during optimization
4460 return true; // pretty stupid...
4461 }
4462
4463 // verify a narrow slice (either incoming or outgoing)
4464 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
4465 if (!VerifyAliases) return; // don't bother to verify unless requested
4466 if (is_error_reported()) return; // muzzle asserts when debugging an error
4467 if (Node::in_dump()) return; // muzzle asserts when printing
4468 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
4469 assert(n != NULL, "");
4470 // Elide intervening MergeMem's
4471 while (n->is_MergeMem()) {
4472 n = n->as_MergeMem()->memory_at(alias_idx);
4473 }
4474 Compile* C = Compile::current();
4475 const TypePtr* n_adr_type = n->adr_type();
4476 if (n == m->empty_memory()) {
4477 // Implicit copy of base_memory()
4478 } else if (n_adr_type != TypePtr::BOTTOM) {
4479 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type");
4480 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
4481 } else {
4482 // A few places like make_runtime_call "know" that VM calls are narrow,
4483 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
4484 bool expected_wide_mem = false;
4485 if (n == m->base_memory()) {
4486 expected_wide_mem = true;
4487 } else if (alias_idx == Compile::AliasIdxRaw ||
4488 n == m->memory_at(Compile::AliasIdxRaw)) {
4489 expected_wide_mem = true;
4490 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
4491 // memory can "leak through" calls on channels that
4492 // are write-once. Allow this also.
4493 expected_wide_mem = true;
4494 }
4495 assert(expected_wide_mem, "expected narrow slice replacement");
4496 }
4497 }
4498 #else // !ASSERT
4499 #define verify_memory_slice(m,i,n) (void)(0) // PRODUCT version is no-op
4500 #endif
4501
4502
4503 //-----------------------------memory_at---------------------------------------
4504 Node* MergeMemNode::memory_at(uint alias_idx) const {
4505 assert(alias_idx >= Compile::AliasIdxRaw ||
4506 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0,
4507 "must avoid base_memory and AliasIdxTop");
4508
4509 // Otherwise, it is a narrow slice.
4510 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
4511 Compile *C = Compile::current();
4512 if (is_empty_memory(n)) {
4513 // the array is sparse; empty slots are the "top" node
4514 n = base_memory();
4515 assert(Node::in_dump()
4516 || n == NULL || n->bottom_type() == Type::TOP
4517 || n->adr_type() == NULL // address is TOP
4518 || n->adr_type() == TypePtr::BOTTOM
4519 || n->adr_type() == TypeRawPtr::BOTTOM
4520 || Compile::current()->AliasLevel() == 0,
4521 "must be a wide memory");
4522 // AliasLevel == 0 if we are organizing the memory states manually.
4523 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
4524 } else {
4525 // make sure the stored slice is sane
4526 #ifdef ASSERT
4527 if (is_error_reported() || Node::in_dump()) {
4528 } else if (might_be_same(n, base_memory())) {
4529 // Give it a pass: It is a mostly harmless repetition of the base.
4530 // This can arise normally from node subsumption during optimization.
4531 } else {
4532 verify_memory_slice(this, alias_idx, n);
4533 }
4534 #endif
4535 }
4536 return n;
4537 }
4538
4539 //---------------------------set_memory_at-------------------------------------
4540 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
4541 verify_memory_slice(this, alias_idx, n);
4542 Node* empty_mem = empty_memory();
4543 if (n == base_memory()) n = empty_mem; // collapse default
4544 uint need_req = alias_idx+1;
4545 if (req() < need_req) {
4546 if (n == empty_mem) return; // already the default, so do not grow me
4547 // grow the sparse array
4548 do {
4549 add_req(empty_mem);
4550 } while (req() < need_req);
4551 }
4552 set_req( alias_idx, n );
4553 }
4554
4555
4556
4557 //--------------------------iteration_setup------------------------------------
4558 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
4559 if (other != NULL) {
4560 grow_to_match(other);
4561 // invariant: the finite support of mm2 is within mm->req()
4562 #ifdef ASSERT
4563 for (uint i = req(); i < other->req(); i++) {
4564 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
4565 }
4566 #endif
4567 }
4568 // Replace spurious copies of base_memory by top.
4569 Node* base_mem = base_memory();
4570 if (base_mem != NULL && !base_mem->is_top()) {
4571 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
4572 if (in(i) == base_mem)
4573 set_req(i, empty_memory());
4574 }
4575 }
4576 }
4577
4578 //---------------------------grow_to_match-------------------------------------
4579 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
4580 Node* empty_mem = empty_memory();
4581 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
4582 // look for the finite support of the other memory
4583 for (uint i = other->req(); --i >= req(); ) {
4584 if (other->in(i) != empty_mem) {
4585 uint new_len = i+1;
4586 while (req() < new_len) add_req(empty_mem);
4587 break;
4588 }
4589 }
4590 }
4591
4592 //---------------------------verify_sparse-------------------------------------
4593 #ifndef PRODUCT
4594 bool MergeMemNode::verify_sparse() const {
4595 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
4596 Node* base_mem = base_memory();
4597 // The following can happen in degenerate cases, since empty==top.
4598 if (is_empty_memory(base_mem)) return true;
4599 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4600 assert(in(i) != NULL, "sane slice");
4601 if (in(i) == base_mem) return false; // should have been the sentinel value!
4602 }
4603 return true;
4604 }
4605
4606 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
4607 Node* n;
4608 n = mm->in(idx);
4609 if (mem == n) return true; // might be empty_memory()
4610 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
4611 if (mem == n) return true;
4612 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) {
4613 if (mem == n) return true;
4614 if (n == NULL) break;
4615 }
4616 return false;
4617 }
4618 #endif // !PRODUCT