1 /*
2 * Copyright (c) 1997, 2017, 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 bool MemNode::check_if_adr_maybe_raw(Node* adr) {
59 if (adr != NULL) {
60 if (adr->bottom_type()->base() == Type::RawPtr || adr->bottom_type()->base() == Type::AnyPtr) {
61 return true;
62 }
63 }
64 return false;
65 }
66
67 #ifndef PRODUCT
68 void MemNode::dump_spec(outputStream *st) const {
69 if (in(Address) == NULL) return; // node is dead
70 #ifndef ASSERT
71 // fake the missing field
72 const TypePtr* _adr_type = NULL;
73 if (in(Address) != NULL)
74 _adr_type = in(Address)->bottom_type()->isa_ptr();
75 #endif
76 dump_adr_type(this, _adr_type, st);
77
78 Compile* C = Compile::current();
79 if (C->alias_type(_adr_type)->is_volatile()) {
80 st->print(" Volatile!");
81 }
82 if (_unaligned_access) {
83 st->print(" unaligned");
84 }
85 if (_mismatched_access) {
86 st->print(" mismatched");
87 }
88 }
89
90 void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) {
91 st->print(" @");
92 if (adr_type == NULL) {
93 st->print("NULL");
94 } else {
95 adr_type->dump_on(st);
96 Compile* C = Compile::current();
97 Compile::AliasType* atp = NULL;
98 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type);
99 if (atp == NULL)
100 st->print(", idx=?\?;");
101 else if (atp->index() == Compile::AliasIdxBot)
102 st->print(", idx=Bot;");
103 else if (atp->index() == Compile::AliasIdxTop)
104 st->print(", idx=Top;");
105 else if (atp->index() == Compile::AliasIdxRaw)
106 st->print(", idx=Raw;");
107 else {
108 ciField* field = atp->field();
109 if (field) {
110 st->print(", name=");
111 field->print_name_on(st);
112 }
113 st->print(", idx=%d;", atp->index());
114 }
115 }
116 }
117
118 extern void print_alias_types();
119
120 #endif
121
122 Node *MemNode::optimize_simple_memory_chain(Node *mchain, const TypeOopPtr *t_oop, Node *load, PhaseGVN *phase) {
123 assert((t_oop != NULL), "sanity");
124 bool is_instance = t_oop->is_known_instance_field();
125 bool is_boxed_value_load = t_oop->is_ptr_to_boxed_value() &&
126 (load != NULL) && load->is_Load() &&
127 (phase->is_IterGVN() != NULL);
128 if (!(is_instance || is_boxed_value_load))
129 return mchain; // don't try to optimize non-instance types
130 uint instance_id = t_oop->instance_id();
131 Node *start_mem = phase->C->start()->proj_out(TypeFunc::Memory);
132 Node *prev = NULL;
133 Node *result = mchain;
134 while (prev != result) {
135 prev = result;
136 if (result == start_mem)
137 break; // hit one of our sentinels
138 // skip over a call which does not affect this memory slice
139 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {
140 Node *proj_in = result->in(0);
141 if (proj_in->is_Allocate() && proj_in->_idx == instance_id) {
142 break; // hit one of our sentinels
143 } else if (proj_in->is_Call()) {
144 CallNode *call = proj_in->as_Call();
145 if (!call->may_modify(t_oop, phase)) { // returns false for instances
146 result = call->in(TypeFunc::Memory);
147 }
148 } else if (proj_in->is_Initialize()) {
149 AllocateNode* alloc = proj_in->as_Initialize()->allocation();
150 // Stop if this is the initialization for the object instance which
151 // which contains this memory slice, otherwise skip over it.
152 if ((alloc == NULL) || (alloc->_idx == instance_id)) {
153 break;
154 }
155 if (is_instance) {
156 result = proj_in->in(TypeFunc::Memory);
157 } else if (is_boxed_value_load) {
158 Node* klass = alloc->in(AllocateNode::KlassNode);
159 const TypeKlassPtr* tklass = phase->type(klass)->is_klassptr();
160 if (tklass->klass_is_exact() && !tklass->klass()->equals(t_oop->klass())) {
161 result = proj_in->in(TypeFunc::Memory); // not related allocation
162 }
163 }
164 } else if (proj_in->is_MemBar()) {
165 result = proj_in->in(TypeFunc::Memory);
166 } else {
167 assert(false, "unexpected projection");
168 }
169 } else if (result->is_ClearArray()) {
170 if (!is_instance || !ClearArrayNode::step_through(&result, instance_id, phase)) {
171 // Can not bypass initialization of the instance
172 // we are looking for.
173 break;
174 }
175 // Otherwise skip it (the call updated 'result' value).
176 } else if (result->is_MergeMem()) {
177 result = step_through_mergemem(phase, result->as_MergeMem(), t_oop, NULL, tty);
178 }
179 }
180 return result;
181 }
182
183 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, Node *load, PhaseGVN *phase) {
184 const TypeOopPtr* t_oop = t_adr->isa_oopptr();
185 if (t_oop == NULL)
186 return mchain; // don't try to optimize non-oop types
187 Node* result = optimize_simple_memory_chain(mchain, t_oop, load, phase);
188 bool is_instance = t_oop->is_known_instance_field();
189 PhaseIterGVN *igvn = phase->is_IterGVN();
190 if (is_instance && igvn != NULL && result->is_Phi()) {
191 PhiNode *mphi = result->as_Phi();
192 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
193 const TypePtr *t = mphi->adr_type();
194 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
195 t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
196 t->is_oopptr()->cast_to_exactness(true)
197 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
198 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop) {
199 // clone the Phi with our address type
200 result = mphi->split_out_instance(t_adr, igvn);
201 } else {
202 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain");
203 }
204 }
205 return result;
206 }
207
208 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) {
209 uint alias_idx = phase->C->get_alias_index(tp);
210 Node *mem = mmem;
211 #ifdef ASSERT
212 {
213 // Check that current type is consistent with the alias index used during graph construction
214 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
215 bool consistent = adr_check == NULL || adr_check->empty() ||
216 phase->C->must_alias(adr_check, alias_idx );
217 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
218 if( !consistent && adr_check != NULL && !adr_check->empty() &&
219 tp->isa_aryptr() && tp->offset() == Type::OffsetBot &&
220 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot &&
221 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() ||
222 adr_check->offset() == oopDesc::klass_offset_in_bytes() ||
223 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) {
224 // don't assert if it is dead code.
225 consistent = true;
226 }
227 if( !consistent ) {
228 st->print("alias_idx==%d, adr_check==", alias_idx);
229 if( adr_check == NULL ) {
230 st->print("NULL");
231 } else {
232 adr_check->dump();
233 }
234 st->cr();
235 print_alias_types();
236 assert(consistent, "adr_check must match alias idx");
237 }
238 }
239 #endif
240 // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally
241 // means an array I have not precisely typed yet. Do not do any
242 // alias stuff with it any time soon.
243 const TypeOopPtr *toop = tp->isa_oopptr();
244 if( tp->base() != Type::AnyPtr &&
245 !(toop &&
246 toop->klass() != NULL &&
247 toop->klass()->is_java_lang_Object() &&
248 toop->offset() == Type::OffsetBot) ) {
249 // compress paths and change unreachable cycles to TOP
250 // If not, we can update the input infinitely along a MergeMem cycle
251 // Equivalent code in PhiNode::Ideal
252 Node* m = phase->transform(mmem);
253 // If transformed to a MergeMem, get the desired slice
254 // Otherwise the returned node represents memory for every slice
255 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
256 // Update input if it is progress over what we have now
257 }
258 return mem;
259 }
260
261 //--------------------------Ideal_common---------------------------------------
262 // Look for degenerate control and memory inputs. Bypass MergeMem inputs.
263 // Unhook non-raw memories from complete (macro-expanded) initializations.
264 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
265 // If our control input is a dead region, kill all below the region
266 Node *ctl = in(MemNode::Control);
267 if (ctl && remove_dead_region(phase, can_reshape))
268 return this;
269 ctl = in(MemNode::Control);
270 // Don't bother trying to transform a dead node
271 if (ctl && ctl->is_top()) return NodeSentinel;
272
273 PhaseIterGVN *igvn = phase->is_IterGVN();
274 // Wait if control on the worklist.
275 if (ctl && can_reshape && igvn != NULL) {
276 Node* bol = NULL;
277 Node* cmp = NULL;
278 if (ctl->in(0)->is_If()) {
279 assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity");
280 bol = ctl->in(0)->in(1);
281 if (bol->is_Bool())
282 cmp = ctl->in(0)->in(1)->in(1);
283 }
284 if (igvn->_worklist.member(ctl) ||
285 (bol != NULL && igvn->_worklist.member(bol)) ||
286 (cmp != NULL && igvn->_worklist.member(cmp)) ) {
287 // This control path may be dead.
288 // Delay this memory node transformation until the control is processed.
289 phase->is_IterGVN()->_worklist.push(this);
290 return NodeSentinel; // caller will return NULL
291 }
292 }
293 // Ignore if memory is dead, or self-loop
294 Node *mem = in(MemNode::Memory);
295 if (phase->type( mem ) == Type::TOP) return NodeSentinel; // caller will return NULL
296 assert(mem != this, "dead loop in MemNode::Ideal");
297
298 if (can_reshape && igvn != NULL && igvn->_worklist.member(mem)) {
299 // This memory slice may be dead.
300 // Delay this mem node transformation until the memory is processed.
301 phase->is_IterGVN()->_worklist.push(this);
302 return NodeSentinel; // caller will return NULL
303 }
304
305 Node *address = in(MemNode::Address);
306 const Type *t_adr = phase->type(address);
307 if (t_adr == Type::TOP) return NodeSentinel; // caller will return NULL
308
309 if (can_reshape && igvn != NULL &&
310 (igvn->_worklist.member(address) ||
311 igvn->_worklist.size() > 0 && (t_adr != adr_type())) ) {
312 // The address's base and type may change when the address is processed.
313 // Delay this mem node transformation until the address is processed.
314 phase->is_IterGVN()->_worklist.push(this);
315 return NodeSentinel; // caller will return NULL
316 }
317
318 // Do NOT remove or optimize the next lines: ensure a new alias index
319 // is allocated for an oop pointer type before Escape Analysis.
320 // Note: C++ will not remove it since the call has side effect.
321 if (t_adr->isa_oopptr()) {
322 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr());
323 }
324
325 Node* base = NULL;
326 if (address->is_AddP()) {
327 base = address->in(AddPNode::Base);
328 }
329 if (base != NULL && phase->type(base)->higher_equal(TypePtr::NULL_PTR) &&
330 !t_adr->isa_rawptr()) {
331 // Note: raw address has TOP base and top->higher_equal(TypePtr::NULL_PTR) is true.
332 // Skip this node optimization if its address has TOP base.
333 return NodeSentinel; // caller will return NULL
334 }
335
336 // Avoid independent memory operations
337 Node* old_mem = mem;
338
339 // The code which unhooks non-raw memories from complete (macro-expanded)
340 // initializations was removed. After macro-expansion all stores catched
341 // by Initialize node became raw stores and there is no information
342 // which memory slices they modify. So it is unsafe to move any memory
343 // operation above these stores. Also in most cases hooked non-raw memories
344 // were already unhooked by using information from detect_ptr_independence()
345 // and find_previous_store().
346
347 if (mem->is_MergeMem()) {
348 MergeMemNode* mmem = mem->as_MergeMem();
349 const TypePtr *tp = t_adr->is_ptr();
350
351 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
352 }
353
354 if (mem != old_mem) {
355 set_req(MemNode::Memory, mem);
356 if (can_reshape && old_mem->outcnt() == 0) {
357 igvn->_worklist.push(old_mem);
358 }
359 if (phase->type( mem ) == Type::TOP) return NodeSentinel;
360 return this;
361 }
362
363 // let the subclass continue analyzing...
364 return NULL;
365 }
366
367 // Helper function for proving some simple control dominations.
368 // Attempt to prove that all control inputs of 'dom' dominate 'sub'.
369 // Already assumes that 'dom' is available at 'sub', and that 'sub'
370 // is not a constant (dominated by the method's StartNode).
371 // Used by MemNode::find_previous_store to prove that the
372 // control input of a memory operation predates (dominates)
373 // an allocation it wants to look past.
374 bool MemNode::all_controls_dominate(Node* dom, Node* sub) {
375 if (dom == NULL || dom->is_top() || sub == NULL || sub->is_top())
376 return false; // Conservative answer for dead code
377
378 // Check 'dom'. Skip Proj and CatchProj nodes.
379 dom = dom->find_exact_control(dom);
380 if (dom == NULL || dom->is_top())
381 return false; // Conservative answer for dead code
382
383 if (dom == sub) {
384 // For the case when, for example, 'sub' is Initialize and the original
385 // 'dom' is Proj node of the 'sub'.
386 return false;
387 }
388
389 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub)
390 return true;
391
392 // 'dom' dominates 'sub' if its control edge and control edges
393 // of all its inputs dominate or equal to sub's control edge.
394
395 // Currently 'sub' is either Allocate, Initialize or Start nodes.
396 // Or Region for the check in LoadNode::Ideal();
397 // 'sub' should have sub->in(0) != NULL.
398 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() ||
399 sub->is_Region() || sub->is_Call(), "expecting only these nodes");
400
401 // Get control edge of 'sub'.
402 Node* orig_sub = sub;
403 sub = sub->find_exact_control(sub->in(0));
404 if (sub == NULL || sub->is_top())
405 return false; // Conservative answer for dead code
406
407 assert(sub->is_CFG(), "expecting control");
408
409 if (sub == dom)
410 return true;
411
412 if (sub->is_Start() || sub->is_Root())
413 return false;
414
415 {
416 // Check all control edges of 'dom'.
417
418 ResourceMark rm;
419 Arena* arena = Thread::current()->resource_area();
420 Node_List nlist(arena);
421 Unique_Node_List dom_list(arena);
422
423 dom_list.push(dom);
424 bool only_dominating_controls = false;
425
426 for (uint next = 0; next < dom_list.size(); next++) {
427 Node* n = dom_list.at(next);
428 if (n == orig_sub)
429 return false; // One of dom's inputs dominated by sub.
430 if (!n->is_CFG() && n->pinned()) {
431 // Check only own control edge for pinned non-control nodes.
432 n = n->find_exact_control(n->in(0));
433 if (n == NULL || n->is_top())
434 return false; // Conservative answer for dead code
435 assert(n->is_CFG(), "expecting control");
436 dom_list.push(n);
437 } else if (n->is_Con() || n->is_Start() || n->is_Root()) {
438 only_dominating_controls = true;
439 } else if (n->is_CFG()) {
440 if (n->dominates(sub, nlist))
441 only_dominating_controls = true;
442 else
443 return false;
444 } else {
445 // First, own control edge.
446 Node* m = n->find_exact_control(n->in(0));
447 if (m != NULL) {
448 if (m->is_top())
449 return false; // Conservative answer for dead code
450 dom_list.push(m);
451 }
452 // Now, the rest of edges.
453 uint cnt = n->req();
454 for (uint i = 1; i < cnt; i++) {
455 m = n->find_exact_control(n->in(i));
456 if (m == NULL || m->is_top())
457 continue;
458 dom_list.push(m);
459 }
460 }
461 }
462 return only_dominating_controls;
463 }
464 }
465
466 //---------------------detect_ptr_independence---------------------------------
467 // Used by MemNode::find_previous_store to prove that two base
468 // pointers are never equal.
469 // The pointers are accompanied by their associated allocations,
470 // if any, which have been previously discovered by the caller.
471 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
472 Node* p2, AllocateNode* a2,
473 PhaseTransform* phase) {
474 // Attempt to prove that these two pointers cannot be aliased.
475 // They may both manifestly be allocations, and they should differ.
476 // Or, if they are not both allocations, they can be distinct constants.
477 // Otherwise, one is an allocation and the other a pre-existing value.
478 if (a1 == NULL && a2 == NULL) { // neither an allocation
479 return (p1 != p2) && p1->is_Con() && p2->is_Con();
480 } else if (a1 != NULL && a2 != NULL) { // both allocations
481 return (a1 != a2);
482 } else if (a1 != NULL) { // one allocation a1
483 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.)
484 return all_controls_dominate(p2, a1);
485 } else { //(a2 != NULL) // one allocation a2
486 return all_controls_dominate(p1, a2);
487 }
488 return false;
489 }
490
491
492 // The logic for reordering loads and stores uses four steps:
493 // (a) Walk carefully past stores and initializations which we
494 // can prove are independent of this load.
495 // (b) Observe that the next memory state makes an exact match
496 // with self (load or store), and locate the relevant store.
497 // (c) Ensure that, if we were to wire self directly to the store,
498 // the optimizer would fold it up somehow.
499 // (d) Do the rewiring, and return, depending on some other part of
500 // the optimizer to fold up the load.
501 // This routine handles steps (a) and (b). Steps (c) and (d) are
502 // specific to loads and stores, so they are handled by the callers.
503 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.)
504 //
505 Node* MemNode::find_previous_store(PhaseTransform* phase) {
506 Node* ctrl = in(MemNode::Control);
507 Node* adr = in(MemNode::Address);
508 intptr_t offset = 0;
509 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
510 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase);
511
512 if (offset == Type::OffsetBot)
513 return NULL; // cannot unalias unless there are precise offsets
514
515 const bool adr_maybe_raw = check_if_adr_maybe_raw(adr);
516 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr();
517
518 intptr_t size_in_bytes = memory_size();
519
520 Node* mem = in(MemNode::Memory); // start searching here...
521
522 int cnt = 50; // Cycle limiter
523 for (;;) { // While we can dance past unrelated stores...
524 if (--cnt < 0) break; // Caught in cycle or a complicated dance?
525
526 if (mem->is_Store()) {
527 Node* st_adr = mem->in(MemNode::Address);
528 intptr_t st_offset = 0;
529 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
530 if (st_base == NULL)
531 break; // inscrutable pointer
532
533 // For raw accesses it's not enough to prove that constant offsets don't intersect.
534 // We need the bases to be the equal in order for the offset check to make sense.
535 if ((adr_maybe_raw || check_if_adr_maybe_raw(st_adr)) && st_base != base) {
536 break;
537 }
538
539 if (st_offset != offset && st_offset != Type::OffsetBot) {
540 const int MAX_STORE = BytesPerLong;
541 if (st_offset >= offset + size_in_bytes ||
542 st_offset <= offset - MAX_STORE ||
543 st_offset <= offset - mem->as_Store()->memory_size()) {
544 // Success: The offsets are provably independent.
545 // (You may ask, why not just test st_offset != offset and be done?
546 // The answer is that stores of different sizes can co-exist
547 // in the same sequence of RawMem effects. We sometimes initialize
548 // a whole 'tile' of array elements with a single jint or jlong.)
549 mem = mem->in(MemNode::Memory);
550 continue; // (a) advance through independent store memory
551 }
552 }
553 if (st_base != base &&
554 detect_ptr_independence(base, alloc,
555 st_base,
556 AllocateNode::Ideal_allocation(st_base, phase),
557 phase)) {
558 // Success: The bases are provably independent.
559 mem = mem->in(MemNode::Memory);
560 continue; // (a) advance through independent store memory
561 }
562
563 // (b) At this point, if the bases or offsets do not agree, we lose,
564 // since we have not managed to prove 'this' and 'mem' independent.
565 if (st_base == base && st_offset == offset) {
566 return mem; // let caller handle steps (c), (d)
567 }
568
569 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
570 InitializeNode* st_init = mem->in(0)->as_Initialize();
571 AllocateNode* st_alloc = st_init->allocation();
572 if (st_alloc == NULL)
573 break; // something degenerated
574 bool known_identical = false;
575 bool known_independent = false;
576 if (alloc == st_alloc)
577 known_identical = true;
578 else if (alloc != NULL)
579 known_independent = true;
580 else if (all_controls_dominate(this, st_alloc))
581 known_independent = true;
582
583 if (known_independent) {
584 // The bases are provably independent: Either they are
585 // manifestly distinct allocations, or else the control
586 // of this load dominates the store's allocation.
587 int alias_idx = phase->C->get_alias_index(adr_type());
588 if (alias_idx == Compile::AliasIdxRaw) {
589 mem = st_alloc->in(TypeFunc::Memory);
590 } else {
591 mem = st_init->memory(alias_idx);
592 }
593 continue; // (a) advance through independent store memory
594 }
595
596 // (b) at this point, if we are not looking at a store initializing
597 // the same allocation we are loading from, we lose.
598 if (known_identical) {
599 // From caller, can_see_stored_value will consult find_captured_store.
600 return mem; // let caller handle steps (c), (d)
601 }
602
603 } else if (addr_t != NULL && addr_t->is_known_instance_field()) {
604 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
605 if (mem->is_Proj() && mem->in(0)->is_Call()) {
606 CallNode *call = mem->in(0)->as_Call();
607 if (!call->may_modify(addr_t, phase)) {
608 mem = call->in(TypeFunc::Memory);
609 continue; // (a) advance through independent call memory
610 }
611 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) {
612 mem = mem->in(0)->in(TypeFunc::Memory);
613 continue; // (a) advance through independent MemBar memory
614 } else if (mem->is_ClearArray()) {
615 if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) {
616 // (the call updated 'mem' value)
617 continue; // (a) advance through independent allocation memory
618 } else {
619 // Can not bypass initialization of the instance
620 // we are looking for.
621 return mem;
622 }
623 } else if (mem->is_MergeMem()) {
624 int alias_idx = phase->C->get_alias_index(adr_type());
625 mem = mem->as_MergeMem()->memory_at(alias_idx);
626 continue; // (a) advance through independent MergeMem memory
627 }
628 }
629
630 // Unless there is an explicit 'continue', we must bail out here,
631 // because 'mem' is an inscrutable memory state (e.g., a call).
632 break;
633 }
634
635 return NULL; // bail out
636 }
637
638 //----------------------calculate_adr_type-------------------------------------
639 // Helper function. Notices when the given type of address hits top or bottom.
640 // Also, asserts a cross-check of the type against the expected address type.
641 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
642 if (t == Type::TOP) return NULL; // does not touch memory any more?
643 #ifdef PRODUCT
644 cross_check = NULL;
645 #else
646 if (!VerifyAliases || is_error_reported() || Node::in_dump()) cross_check = NULL;
647 #endif
648 const TypePtr* tp = t->isa_ptr();
649 if (tp == NULL) {
650 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
651 return TypePtr::BOTTOM; // touches lots of memory
652 } else {
653 #ifdef ASSERT
654 // %%%% [phh] We don't check the alias index if cross_check is
655 // TypeRawPtr::BOTTOM. Needs to be investigated.
656 if (cross_check != NULL &&
657 cross_check != TypePtr::BOTTOM &&
658 cross_check != TypeRawPtr::BOTTOM) {
659 // Recheck the alias index, to see if it has changed (due to a bug).
660 Compile* C = Compile::current();
661 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
662 "must stay in the original alias category");
663 // The type of the address must be contained in the adr_type,
664 // disregarding "null"-ness.
665 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
666 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
667 assert(cross_check->meet(tp_notnull) == cross_check->remove_speculative(),
668 "real address must not escape from expected memory type");
669 }
670 #endif
671 return tp;
672 }
673 }
674
675 //------------------------adr_phi_is_loop_invariant----------------------------
676 // A helper function for Ideal_DU_postCCP to check if a Phi in a counted
677 // loop is loop invariant. Make a quick traversal of Phi and associated
678 // CastPP nodes, looking to see if they are a closed group within the loop.
679 bool MemNode::adr_phi_is_loop_invariant(Node* adr_phi, Node* cast) {
680 // The idea is that the phi-nest must boil down to only CastPP nodes
681 // with the same data. This implies that any path into the loop already
682 // includes such a CastPP, and so the original cast, whatever its input,
683 // must be covered by an equivalent cast, with an earlier control input.
684 ResourceMark rm;
685
686 // The loop entry input of the phi should be the unique dominating
687 // node for every Phi/CastPP in the loop.
688 Unique_Node_List closure;
689 closure.push(adr_phi->in(LoopNode::EntryControl));
690
691 // Add the phi node and the cast to the worklist.
692 Unique_Node_List worklist;
693 worklist.push(adr_phi);
694 if( cast != NULL ){
695 if( !cast->is_ConstraintCast() ) return false;
696 worklist.push(cast);
697 }
698
699 // Begin recursive walk of phi nodes.
700 while( worklist.size() ){
701 // Take a node off the worklist
702 Node *n = worklist.pop();
703 if( !closure.member(n) ){
704 // Add it to the closure.
705 closure.push(n);
706 // Make a sanity check to ensure we don't waste too much time here.
707 if( closure.size() > 20) return false;
708 // This node is OK if:
709 // - it is a cast of an identical value
710 // - or it is a phi node (then we add its inputs to the worklist)
711 // Otherwise, the node is not OK, and we presume the cast is not invariant
712 if( n->is_ConstraintCast() ){
713 worklist.push(n->in(1));
714 } else if( n->is_Phi() ) {
715 for( uint i = 1; i < n->req(); i++ ) {
716 worklist.push(n->in(i));
717 }
718 } else {
719 return false;
720 }
721 }
722 }
723
724 // Quit when the worklist is empty, and we've found no offending nodes.
725 return true;
726 }
727
728 //------------------------------Ideal_DU_postCCP-------------------------------
729 // Find any cast-away of null-ness and keep its control. Null cast-aways are
730 // going away in this pass and we need to make this memory op depend on the
731 // gating null check.
732 Node *MemNode::Ideal_DU_postCCP( PhaseCCP *ccp ) {
733 return Ideal_common_DU_postCCP(ccp, this, in(MemNode::Address));
734 }
735
736 // I tried to leave the CastPP's in. This makes the graph more accurate in
737 // some sense; we get to keep around the knowledge that an oop is not-null
738 // after some test. Alas, the CastPP's interfere with GVN (some values are
739 // the regular oop, some are the CastPP of the oop, all merge at Phi's which
740 // cannot collapse, etc). This cost us 10% on SpecJVM, even when I removed
741 // some of the more trivial cases in the optimizer. Removing more useless
742 // Phi's started allowing Loads to illegally float above null checks. I gave
743 // up on this approach. CNC 10/20/2000
744 // This static method may be called not from MemNode (EncodePNode calls it).
745 // Only the control edge of the node 'n' might be updated.
746 Node *MemNode::Ideal_common_DU_postCCP( PhaseCCP *ccp, Node* n, Node* adr ) {
747 Node *skipped_cast = NULL;
748 // Need a null check? Regular static accesses do not because they are
749 // from constant addresses. Array ops are gated by the range check (which
750 // always includes a NULL check). Just check field ops.
751 if( n->in(MemNode::Control) == NULL ) {
752 // Scan upwards for the highest location we can place this memory op.
753 while( true ) {
754 switch( adr->Opcode() ) {
755
756 case Op_AddP: // No change to NULL-ness, so peek thru AddP's
757 adr = adr->in(AddPNode::Base);
758 continue;
759
760 case Op_DecodeN: // No change to NULL-ness, so peek thru
761 case Op_DecodeNKlass:
762 adr = adr->in(1);
763 continue;
764
765 case Op_EncodeP:
766 case Op_EncodePKlass:
767 // EncodeP node's control edge could be set by this method
768 // when EncodeP node depends on CastPP node.
769 //
770 // Use its control edge for memory op because EncodeP may go away
771 // later when it is folded with following or preceding DecodeN node.
772 if (adr->in(0) == NULL) {
773 // Keep looking for cast nodes.
774 adr = adr->in(1);
775 continue;
776 }
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_CastPP:
783 // If the CastPP is useless, just peek on through it.
784 if( ccp->type(adr) == ccp->type(adr->in(1)) ) {
785 // Remember the cast that we've peeked though. If we peek
786 // through more than one, then we end up remembering the highest
787 // one, that is, if in a loop, the one closest to the top.
788 skipped_cast = adr;
789 adr = adr->in(1);
790 continue;
791 }
792 // CastPP is going away in this pass! We need this memory op to be
793 // control-dependent on the test that is guarding the CastPP.
794 ccp->hash_delete(n);
795 n->set_req(MemNode::Control, adr->in(0));
796 ccp->hash_insert(n);
797 return n;
798
799 case Op_Phi:
800 // Attempt to float above a Phi to some dominating point.
801 if (adr->in(0) != NULL && adr->in(0)->is_CountedLoop()) {
802 // If we've already peeked through a Cast (which could have set the
803 // control), we can't float above a Phi, because the skipped Cast
804 // may not be loop invariant.
805 if (adr_phi_is_loop_invariant(adr, skipped_cast)) {
806 adr = adr->in(1);
807 continue;
808 }
809 }
810
811 // Intentional fallthrough!
812
813 // No obvious dominating point. The mem op is pinned below the Phi
814 // by the Phi itself. If the Phi goes away (no true value is merged)
815 // then the mem op can float, but not indefinitely. It must be pinned
816 // behind the controls leading to the Phi.
817 case Op_CheckCastPP:
818 // These usually stick around to change address type, however a
819 // useless one can be elided and we still need to pick up a control edge
820 if (adr->in(0) == NULL) {
821 // This CheckCastPP node has NO control and is likely useless. But we
822 // need check further up the ancestor chain for a control input to keep
823 // the node in place. 4959717.
824 skipped_cast = adr;
825 adr = adr->in(1);
826 continue;
827 }
828 ccp->hash_delete(n);
829 n->set_req(MemNode::Control, adr->in(0));
830 ccp->hash_insert(n);
831 return n;
832
833 // List of "safe" opcodes; those that implicitly block the memory
834 // op below any null check.
835 case Op_CastX2P: // no null checks on native pointers
836 case Op_Parm: // 'this' pointer is not null
837 case Op_LoadP: // Loading from within a klass
838 case Op_LoadN: // Loading from within a klass
839 case Op_LoadKlass: // Loading from within a klass
840 case Op_LoadNKlass: // Loading from within a klass
841 case Op_ConP: // Loading from a klass
842 case Op_ConN: // Loading from a klass
843 case Op_ConNKlass: // Loading from a klass
844 case Op_CreateEx: // Sucking up the guts of an exception oop
845 case Op_Con: // Reading from TLS
846 case Op_CMoveP: // CMoveP is pinned
847 case Op_CMoveN: // CMoveN is pinned
848 break; // No progress
849
850 case Op_Proj: // Direct call to an allocation routine
851 case Op_SCMemProj: // Memory state from store conditional ops
852 #ifdef ASSERT
853 {
854 assert(adr->as_Proj()->_con == TypeFunc::Parms, "must be return value");
855 const Node* call = adr->in(0);
856 if (call->is_CallJava()) {
857 const CallJavaNode* call_java = call->as_CallJava();
858 const TypeTuple *r = call_java->tf()->range();
859 assert(r->cnt() > TypeFunc::Parms, "must return value");
860 const Type* ret_type = r->field_at(TypeFunc::Parms);
861 assert(ret_type && ret_type->isa_ptr(), "must return pointer");
862 // We further presume that this is one of
863 // new_instance_Java, new_array_Java, or
864 // the like, but do not assert for this.
865 } else if (call->is_Allocate()) {
866 // similar case to new_instance_Java, etc.
867 } else if (!call->is_CallLeaf()) {
868 // Projections from fetch_oop (OSR) are allowed as well.
869 ShouldNotReachHere();
870 }
871 }
872 #endif
873 break;
874 default:
875 ShouldNotReachHere();
876 }
877 break;
878 }
879 }
880
881 return NULL; // No progress
882 }
883
884
885 //=============================================================================
886 // Should LoadNode::Ideal() attempt to remove control edges?
887 bool LoadNode::can_remove_control() const {
888 return true;
889 }
890 uint LoadNode::size_of() const { return sizeof(*this); }
891 uint LoadNode::cmp( const Node &n ) const
892 { return !Type::cmp( _type, ((LoadNode&)n)._type ); }
893 const Type *LoadNode::bottom_type() const { return _type; }
894 uint LoadNode::ideal_reg() const {
895 return _type->ideal_reg();
896 }
897
898 #ifndef PRODUCT
899 void LoadNode::dump_spec(outputStream *st) const {
900 MemNode::dump_spec(st);
901 if( !Verbose && !WizardMode ) {
902 // standard dump does this in Verbose and WizardMode
903 st->print(" #"); _type->dump_on(st);
904 }
905 if (!_depends_only_on_test) {
906 st->print(" (does not depend only on test)");
907 }
908 }
909 #endif
910
911 #ifdef ASSERT
912 //----------------------------is_immutable_value-------------------------------
913 // Helper function to allow a raw load without control edge for some cases
914 bool LoadNode::is_immutable_value(Node* adr) {
915 return (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() &&
916 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal &&
917 (adr->in(AddPNode::Offset)->find_intptr_t_con(-1) ==
918 in_bytes(JavaThread::osthread_offset())));
919 }
920 #endif
921
922 //----------------------------LoadNode::make-----------------------------------
923 // Polymorphic factory method:
924 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) {
925 Compile* C = gvn.C;
926
927 // sanity check the alias category against the created node type
928 assert(!(adr_type->isa_oopptr() &&
929 adr_type->offset() == oopDesc::klass_offset_in_bytes()),
930 "use LoadKlassNode instead");
931 assert(!(adr_type->isa_aryptr() &&
932 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
933 "use LoadRangeNode instead");
934 // Check control edge of raw loads
935 assert( ctl != NULL || C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
936 // oop will be recorded in oop map if load crosses safepoint
937 rt->isa_oopptr() || is_immutable_value(adr),
938 "raw memory operations should have control edge");
939 switch (bt) {
940 case T_BOOLEAN: return new (C) LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency);
941 case T_BYTE: return new (C) LoadBNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency);
942 case T_INT: return new (C) LoadINode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency);
943 case T_CHAR: return new (C) LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency);
944 case T_SHORT: return new (C) LoadSNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency);
945 case T_LONG: return new (C) LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency);
946 case T_FLOAT: return new (C) LoadFNode (ctl, mem, adr, adr_type, rt, mo, control_dependency);
947 case T_DOUBLE: return new (C) LoadDNode (ctl, mem, adr, adr_type, rt, mo, control_dependency);
948 case T_ADDRESS: return new (C) LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency);
949 case T_OBJECT:
950 #ifdef _LP64
951 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
952 Node* load = gvn.transform(new (C) LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo, control_dependency));
953 return new (C) DecodeNNode(load, load->bottom_type()->make_ptr());
954 } else
955 #endif
956 {
957 assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop");
958 return new (C) LoadPNode(ctl, mem, adr, adr_type, rt->is_oopptr(), mo, control_dependency);
959 }
960 }
961 ShouldNotReachHere();
962 return (LoadNode*)NULL;
963 }
964
965 LoadLNode* LoadLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo, ControlDependency control_dependency) {
966 bool require_atomic = true;
967 return new (C) LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency, require_atomic);
968 }
969
970 LoadDNode* LoadDNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo, ControlDependency control_dependency) {
971 bool require_atomic = true;
972 return new (C) LoadDNode(ctl, mem, adr, adr_type, rt, mo, control_dependency, require_atomic);
973 }
974
975
976
977 //------------------------------hash-------------------------------------------
978 uint LoadNode::hash() const {
979 // unroll addition of interesting fields
980 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
981 }
982
983 static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) {
984 if ((atp != NULL) && (atp->index() >= Compile::AliasIdxRaw)) {
985 bool non_volatile = (atp->field() != NULL) && !atp->field()->is_volatile();
986 bool is_stable_ary = FoldStableValues &&
987 (tp != NULL) && (tp->isa_aryptr() != NULL) &&
988 tp->isa_aryptr()->is_stable();
989
990 return (eliminate_boxing && non_volatile) || is_stable_ary;
991 }
992
993 return false;
994 }
995
996 //---------------------------can_see_stored_value------------------------------
997 // This routine exists to make sure this set of tests is done the same
998 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
999 // will change the graph shape in a way which makes memory alive twice at the
1000 // same time (uses the Oracle model of aliasing), then some
1001 // LoadXNode::Identity will fold things back to the equivalence-class model
1002 // of aliasing.
1003 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const {
1004 Node* ld_adr = in(MemNode::Address);
1005 intptr_t ld_off = 0;
1006 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
1007 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
1008 Compile::AliasType* atp = (tp != NULL) ? phase->C->alias_type(tp) : NULL;
1009 // This is more general than load from boxing objects.
1010 if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) {
1011 uint alias_idx = atp->index();
1012 bool final = !atp->is_rewritable();
1013 Node* result = NULL;
1014 Node* current = st;
1015 // Skip through chains of MemBarNodes checking the MergeMems for
1016 // new states for the slice of this load. Stop once any other
1017 // kind of node is encountered. Loads from final memory can skip
1018 // through any kind of MemBar but normal loads shouldn't skip
1019 // through MemBarAcquire since the could allow them to move out of
1020 // a synchronized region.
1021 while (current->is_Proj()) {
1022 int opc = current->in(0)->Opcode();
1023 if ((final && (opc == Op_MemBarAcquire ||
1024 opc == Op_MemBarAcquireLock ||
1025 opc == Op_LoadFence)) ||
1026 opc == Op_MemBarRelease ||
1027 opc == Op_StoreFence ||
1028 opc == Op_MemBarReleaseLock ||
1029 opc == Op_MemBarCPUOrder) {
1030 Node* mem = current->in(0)->in(TypeFunc::Memory);
1031 if (mem->is_MergeMem()) {
1032 MergeMemNode* merge = mem->as_MergeMem();
1033 Node* new_st = merge->memory_at(alias_idx);
1034 if (new_st == merge->base_memory()) {
1035 // Keep searching
1036 current = new_st;
1037 continue;
1038 }
1039 // Save the new memory state for the slice and fall through
1040 // to exit.
1041 result = new_st;
1042 }
1043 }
1044 break;
1045 }
1046 if (result != NULL) {
1047 st = result;
1048 }
1049 }
1050
1051 // Loop around twice in the case Load -> Initialize -> Store.
1052 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
1053 for (int trip = 0; trip <= 1; trip++) {
1054
1055 if (st->is_Store()) {
1056 Node* st_adr = st->in(MemNode::Address);
1057 if (!phase->eqv(st_adr, ld_adr)) {
1058 // Try harder before giving up... Match raw and non-raw pointers.
1059 intptr_t st_off = 0;
1060 AllocateNode* alloc = AllocateNode::Ideal_allocation(st_adr, phase, st_off);
1061 if (alloc == NULL) return NULL;
1062 if (alloc != ld_alloc) return NULL;
1063 if (ld_off != st_off) return NULL;
1064 // At this point we have proven something like this setup:
1065 // A = Allocate(...)
1066 // L = LoadQ(, AddP(CastPP(, A.Parm),, #Off))
1067 // S = StoreQ(, AddP(, A.Parm , #Off), V)
1068 // (Actually, we haven't yet proven the Q's are the same.)
1069 // In other words, we are loading from a casted version of
1070 // the same pointer-and-offset that we stored to.
1071 // Thus, we are able to replace L by V.
1072 }
1073 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
1074 if (store_Opcode() != st->Opcode())
1075 return NULL;
1076 return st->in(MemNode::ValueIn);
1077 }
1078
1079 // A load from a freshly-created object always returns zero.
1080 // (This can happen after LoadNode::Ideal resets the load's memory input
1081 // to find_captured_store, which returned InitializeNode::zero_memory.)
1082 if (st->is_Proj() && st->in(0)->is_Allocate() &&
1083 (st->in(0) == ld_alloc) &&
1084 (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) {
1085 // return a zero value for the load's basic type
1086 // (This is one of the few places where a generic PhaseTransform
1087 // can create new nodes. Think of it as lazily manifesting
1088 // virtually pre-existing constants.)
1089 return phase->zerocon(memory_type());
1090 }
1091
1092 // A load from an initialization barrier can match a captured store.
1093 if (st->is_Proj() && st->in(0)->is_Initialize()) {
1094 InitializeNode* init = st->in(0)->as_Initialize();
1095 AllocateNode* alloc = init->allocation();
1096 if ((alloc != NULL) && (alloc == ld_alloc)) {
1097 // examine a captured store value
1098 st = init->find_captured_store(ld_off, memory_size(), phase);
1099 if (st != NULL)
1100 continue; // take one more trip around
1101 }
1102 }
1103
1104 // Load boxed value from result of valueOf() call is input parameter.
1105 if (this->is_Load() && ld_adr->is_AddP() &&
1106 (tp != NULL) && tp->is_ptr_to_boxed_value()) {
1107 intptr_t ignore = 0;
1108 Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore);
1109 if (base != NULL && base->is_Proj() &&
1110 base->as_Proj()->_con == TypeFunc::Parms &&
1111 base->in(0)->is_CallStaticJava() &&
1112 base->in(0)->as_CallStaticJava()->is_boxing_method()) {
1113 return base->in(0)->in(TypeFunc::Parms);
1114 }
1115 }
1116
1117 break;
1118 }
1119
1120 return NULL;
1121 }
1122
1123 //----------------------is_instance_field_load_with_local_phi------------------
1124 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
1125 if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl &&
1126 in(Address)->is_AddP() ) {
1127 const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr();
1128 // Only instances and boxed values.
1129 if( t_oop != NULL &&
1130 (t_oop->is_ptr_to_boxed_value() ||
1131 t_oop->is_known_instance_field()) &&
1132 t_oop->offset() != Type::OffsetBot &&
1133 t_oop->offset() != Type::OffsetTop) {
1134 return true;
1135 }
1136 }
1137 return false;
1138 }
1139
1140 //------------------------------Identity---------------------------------------
1141 // Loads are identity if previous store is to same address
1142 Node *LoadNode::Identity( PhaseTransform *phase ) {
1143 // If the previous store-maker is the right kind of Store, and the store is
1144 // to the same address, then we are equal to the value stored.
1145 Node* mem = in(Memory);
1146 Node* value = can_see_stored_value(mem, phase);
1147 if( value ) {
1148 // byte, short & char stores truncate naturally.
1149 // A load has to load the truncated value which requires
1150 // some sort of masking operation and that requires an
1151 // Ideal call instead of an Identity call.
1152 if (memory_size() < BytesPerInt) {
1153 // If the input to the store does not fit with the load's result type,
1154 // it must be truncated via an Ideal call.
1155 if (!phase->type(value)->higher_equal(phase->type(this)))
1156 return this;
1157 }
1158 // (This works even when value is a Con, but LoadNode::Value
1159 // usually runs first, producing the singleton type of the Con.)
1160 return value;
1161 }
1162
1163 // Search for an existing data phi which was generated before for the same
1164 // instance's field to avoid infinite generation of phis in a loop.
1165 Node *region = mem->in(0);
1166 if (is_instance_field_load_with_local_phi(region)) {
1167 const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr();
1168 int this_index = phase->C->get_alias_index(addr_t);
1169 int this_offset = addr_t->offset();
1170 int this_iid = addr_t->instance_id();
1171 if (!addr_t->is_known_instance() &&
1172 addr_t->is_ptr_to_boxed_value()) {
1173 // Use _idx of address base (could be Phi node) for boxed values.
1174 intptr_t ignore = 0;
1175 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1176 if (base == NULL) {
1177 return this;
1178 }
1179 this_iid = base->_idx;
1180 }
1181 const Type* this_type = bottom_type();
1182 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1183 Node* phi = region->fast_out(i);
1184 if (phi->is_Phi() && phi != mem &&
1185 phi->as_Phi()->is_same_inst_field(this_type, (int)mem->_idx, this_iid, this_index, this_offset)) {
1186 return phi;
1187 }
1188 }
1189 }
1190
1191 return this;
1192 }
1193
1194 // We're loading from an object which has autobox behaviour.
1195 // If this object is result of a valueOf call we'll have a phi
1196 // merging a newly allocated object and a load from the cache.
1197 // We want to replace this load with the original incoming
1198 // argument to the valueOf call.
1199 Node* LoadNode::eliminate_autobox(PhaseGVN* phase) {
1200 assert(phase->C->eliminate_boxing(), "sanity");
1201 intptr_t ignore = 0;
1202 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1203 if ((base == NULL) || base->is_Phi()) {
1204 // Push the loads from the phi that comes from valueOf up
1205 // through it to allow elimination of the loads and the recovery
1206 // of the original value. It is done in split_through_phi().
1207 return NULL;
1208 } else if (base->is_Load() ||
1209 base->is_DecodeN() && base->in(1)->is_Load()) {
1210 // Eliminate the load of boxed value for integer types from the cache
1211 // array by deriving the value from the index into the array.
1212 // Capture the offset of the load and then reverse the computation.
1213
1214 // Get LoadN node which loads a boxing object from 'cache' array.
1215 if (base->is_DecodeN()) {
1216 base = base->in(1);
1217 }
1218 if (!base->in(Address)->is_AddP()) {
1219 return NULL; // Complex address
1220 }
1221 AddPNode* address = base->in(Address)->as_AddP();
1222 Node* cache_base = address->in(AddPNode::Base);
1223 if ((cache_base != NULL) && cache_base->is_DecodeN()) {
1224 // Get ConP node which is static 'cache' field.
1225 cache_base = cache_base->in(1);
1226 }
1227 if ((cache_base != NULL) && cache_base->is_Con()) {
1228 const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr();
1229 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1230 Node* elements[4];
1231 int shift = exact_log2(type2aelembytes(T_OBJECT));
1232 int count = address->unpack_offsets(elements, ARRAY_SIZE(elements));
1233 if ((count > 0) && elements[0]->is_Con() &&
1234 ((count == 1) ||
1235 (count == 2) && elements[1]->Opcode() == Op_LShiftX &&
1236 elements[1]->in(2) == phase->intcon(shift))) {
1237 ciObjArray* array = base_type->const_oop()->as_obj_array();
1238 // Fetch the box object cache[0] at the base of the array and get its value
1239 ciInstance* box = array->obj_at(0)->as_instance();
1240 ciInstanceKlass* ik = box->klass()->as_instance_klass();
1241 assert(ik->is_box_klass(), "sanity");
1242 assert(ik->nof_nonstatic_fields() == 1, "change following code");
1243 if (ik->nof_nonstatic_fields() == 1) {
1244 // This should be true nonstatic_field_at requires calling
1245 // nof_nonstatic_fields so check it anyway
1246 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1247 BasicType bt = c.basic_type();
1248 // Only integer types have boxing cache.
1249 assert(bt == T_BOOLEAN || bt == T_CHAR ||
1250 bt == T_BYTE || bt == T_SHORT ||
1251 bt == T_INT || bt == T_LONG, err_msg_res("wrong type = %s", type2name(bt)));
1252 jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int();
1253 if (cache_low != (int)cache_low) {
1254 return NULL; // should not happen since cache is array indexed by value
1255 }
1256 jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift);
1257 if (offset != (int)offset) {
1258 return NULL; // should not happen since cache is array indexed by value
1259 }
1260 // Add up all the offsets making of the address of the load
1261 Node* result = elements[0];
1262 for (int i = 1; i < count; i++) {
1263 result = phase->transform(new (phase->C) AddXNode(result, elements[i]));
1264 }
1265 // Remove the constant offset from the address and then
1266 result = phase->transform(new (phase->C) AddXNode(result, phase->MakeConX(-(int)offset)));
1267 // remove the scaling of the offset to recover the original index.
1268 if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) {
1269 // Peel the shift off directly but wrap it in a dummy node
1270 // since Ideal can't return existing nodes
1271 result = new (phase->C) RShiftXNode(result->in(1), phase->intcon(0));
1272 } else if (result->is_Add() && result->in(2)->is_Con() &&
1273 result->in(1)->Opcode() == Op_LShiftX &&
1274 result->in(1)->in(2) == phase->intcon(shift)) {
1275 // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z)
1276 // but for boxing cache access we know that X<<Z will not overflow
1277 // (there is range check) so we do this optimizatrion by hand here.
1278 Node* add_con = new (phase->C) RShiftXNode(result->in(2), phase->intcon(shift));
1279 result = new (phase->C) AddXNode(result->in(1)->in(1), phase->transform(add_con));
1280 } else {
1281 result = new (phase->C) RShiftXNode(result, phase->intcon(shift));
1282 }
1283 #ifdef _LP64
1284 if (bt != T_LONG) {
1285 result = new (phase->C) ConvL2INode(phase->transform(result));
1286 }
1287 #else
1288 if (bt == T_LONG) {
1289 result = new (phase->C) ConvI2LNode(phase->transform(result));
1290 }
1291 #endif
1292 // Boxing/unboxing can be done from signed & unsigned loads (e.g. LoadUB -> ... -> LoadB pair).
1293 // Need to preserve unboxing load type if it is unsigned.
1294 switch(this->Opcode()) {
1295 case Op_LoadUB:
1296 result = new (phase->C) AndINode(phase->transform(result), phase->intcon(0xFF));
1297 break;
1298 case Op_LoadUS:
1299 result = new (phase->C) AndINode(phase->transform(result), phase->intcon(0xFFFF));
1300 break;
1301 }
1302 return result;
1303 }
1304 }
1305 }
1306 }
1307 }
1308 return NULL;
1309 }
1310
1311 static bool stable_phi(PhiNode* phi, PhaseGVN *phase) {
1312 Node* region = phi->in(0);
1313 if (region == NULL) {
1314 return false; // Wait stable graph
1315 }
1316 uint cnt = phi->req();
1317 for (uint i = 1; i < cnt; i++) {
1318 Node* rc = region->in(i);
1319 if (rc == NULL || phase->type(rc) == Type::TOP)
1320 return false; // Wait stable graph
1321 Node* in = phi->in(i);
1322 if (in == NULL || phase->type(in) == Type::TOP)
1323 return false; // Wait stable graph
1324 }
1325 return true;
1326 }
1327 //------------------------------split_through_phi------------------------------
1328 // Split instance or boxed field load through Phi.
1329 Node *LoadNode::split_through_phi(PhaseGVN *phase) {
1330 Node* mem = in(Memory);
1331 Node* address = in(Address);
1332 const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr();
1333
1334 assert((t_oop != NULL) &&
1335 (t_oop->is_known_instance_field() ||
1336 t_oop->is_ptr_to_boxed_value()), "invalide conditions");
1337
1338 Compile* C = phase->C;
1339 intptr_t ignore = 0;
1340 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1341 bool base_is_phi = (base != NULL) && base->is_Phi();
1342 bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() &&
1343 (base != NULL) && (base == address->in(AddPNode::Base)) &&
1344 phase->type(base)->higher_equal(TypePtr::NOTNULL);
1345
1346 if (!((mem->is_Phi() || base_is_phi) &&
1347 (load_boxed_values || t_oop->is_known_instance_field()))) {
1348 return NULL; // memory is not Phi
1349 }
1350
1351 if (mem->is_Phi()) {
1352 if (!stable_phi(mem->as_Phi(), phase)) {
1353 return NULL; // Wait stable graph
1354 }
1355 uint cnt = mem->req();
1356 // Check for loop invariant memory.
1357 if (cnt == 3) {
1358 for (uint i = 1; i < cnt; i++) {
1359 Node* in = mem->in(i);
1360 Node* m = optimize_memory_chain(in, t_oop, this, phase);
1361 if (m == mem) {
1362 if (i == 1) {
1363 // if the first edge was a loop, check second edge too.
1364 // If both are replaceable - we are in an infinite loop
1365 Node *n = optimize_memory_chain(mem->in(2), t_oop, this, phase);
1366 if (n == mem) {
1367 break;
1368 }
1369 }
1370 set_req(Memory, mem->in(cnt - i));
1371 return this; // made change
1372 }
1373 }
1374 }
1375 }
1376 if (base_is_phi) {
1377 if (!stable_phi(base->as_Phi(), phase)) {
1378 return NULL; // Wait stable graph
1379 }
1380 uint cnt = base->req();
1381 // Check for loop invariant memory.
1382 if (cnt == 3) {
1383 for (uint i = 1; i < cnt; i++) {
1384 if (base->in(i) == base) {
1385 return NULL; // Wait stable graph
1386 }
1387 }
1388 }
1389 }
1390
1391 bool load_boxed_phi = load_boxed_values && base_is_phi && (base->in(0) == mem->in(0));
1392
1393 // Split through Phi (see original code in loopopts.cpp).
1394 assert(C->have_alias_type(t_oop), "instance should have alias type");
1395
1396 // Do nothing here if Identity will find a value
1397 // (to avoid infinite chain of value phis generation).
1398 if (!phase->eqv(this, this->Identity(phase)))
1399 return NULL;
1400
1401 // Select Region to split through.
1402 Node* region;
1403 if (!base_is_phi) {
1404 assert(mem->is_Phi(), "sanity");
1405 region = mem->in(0);
1406 // Skip if the region dominates some control edge of the address.
1407 if (!MemNode::all_controls_dominate(address, region))
1408 return NULL;
1409 } else if (!mem->is_Phi()) {
1410 assert(base_is_phi, "sanity");
1411 region = base->in(0);
1412 // Skip if the region dominates some control edge of the memory.
1413 if (!MemNode::all_controls_dominate(mem, region))
1414 return NULL;
1415 } else if (base->in(0) != mem->in(0)) {
1416 assert(base_is_phi && mem->is_Phi(), "sanity");
1417 if (MemNode::all_controls_dominate(mem, base->in(0))) {
1418 region = base->in(0);
1419 } else if (MemNode::all_controls_dominate(address, mem->in(0))) {
1420 region = mem->in(0);
1421 } else {
1422 return NULL; // complex graph
1423 }
1424 } else {
1425 assert(base->in(0) == mem->in(0), "sanity");
1426 region = mem->in(0);
1427 }
1428
1429 const Type* this_type = this->bottom_type();
1430 int this_index = C->get_alias_index(t_oop);
1431 int this_offset = t_oop->offset();
1432 int this_iid = t_oop->instance_id();
1433 if (!t_oop->is_known_instance() && load_boxed_values) {
1434 // Use _idx of address base for boxed values.
1435 this_iid = base->_idx;
1436 }
1437 PhaseIterGVN* igvn = phase->is_IterGVN();
1438 Node* phi = new (C) PhiNode(region, this_type, NULL, mem->_idx, this_iid, this_index, this_offset);
1439 for (uint i = 1; i < region->req(); i++) {
1440 Node* x;
1441 Node* the_clone = NULL;
1442 if (region->in(i) == C->top()) {
1443 x = C->top(); // Dead path? Use a dead data op
1444 } else {
1445 x = this->clone(); // Else clone up the data op
1446 the_clone = x; // Remember for possible deletion.
1447 // Alter data node to use pre-phi inputs
1448 if (this->in(0) == region) {
1449 x->set_req(0, region->in(i));
1450 } else {
1451 x->set_req(0, NULL);
1452 }
1453 if (mem->is_Phi() && (mem->in(0) == region)) {
1454 x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone.
1455 }
1456 if (address->is_Phi() && address->in(0) == region) {
1457 x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone
1458 }
1459 if (base_is_phi && (base->in(0) == region)) {
1460 Node* base_x = base->in(i); // Clone address for loads from boxed objects.
1461 Node* adr_x = phase->transform(new (C) AddPNode(base_x,base_x,address->in(AddPNode::Offset)));
1462 x->set_req(Address, adr_x);
1463 }
1464 }
1465 // Check for a 'win' on some paths
1466 const Type *t = x->Value(igvn);
1467
1468 bool singleton = t->singleton();
1469
1470 // See comments in PhaseIdealLoop::split_thru_phi().
1471 if (singleton && t == Type::TOP) {
1472 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1473 }
1474
1475 if (singleton) {
1476 x = igvn->makecon(t);
1477 } else {
1478 // We now call Identity to try to simplify the cloned node.
1479 // Note that some Identity methods call phase->type(this).
1480 // Make sure that the type array is big enough for
1481 // our new node, even though we may throw the node away.
1482 // (This tweaking with igvn only works because x is a new node.)
1483 igvn->set_type(x, t);
1484 // If x is a TypeNode, capture any more-precise type permanently into Node
1485 // otherwise it will be not updated during igvn->transform since
1486 // igvn->type(x) is set to x->Value() already.
1487 x->raise_bottom_type(t);
1488 Node *y = x->Identity(igvn);
1489 if (y != x) {
1490 x = y;
1491 } else {
1492 y = igvn->hash_find_insert(x);
1493 if (y) {
1494 x = y;
1495 } else {
1496 // Else x is a new node we are keeping
1497 // We do not need register_new_node_with_optimizer
1498 // because set_type has already been called.
1499 igvn->_worklist.push(x);
1500 }
1501 }
1502 }
1503 if (x != the_clone && the_clone != NULL) {
1504 igvn->remove_dead_node(the_clone);
1505 }
1506 phi->set_req(i, x);
1507 }
1508 // Record Phi
1509 igvn->register_new_node_with_optimizer(phi);
1510 return phi;
1511 }
1512
1513 //------------------------------Ideal------------------------------------------
1514 // If the load is from Field memory and the pointer is non-null, it might be possible to
1515 // zero out the control input.
1516 // If the offset is constant and the base is an object allocation,
1517 // try to hook me up to the exact initializing store.
1518 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1519 Node* p = MemNode::Ideal_common(phase, can_reshape);
1520 if (p) return (p == NodeSentinel) ? NULL : p;
1521
1522 Node* ctrl = in(MemNode::Control);
1523 Node* address = in(MemNode::Address);
1524
1525 bool addr_mark = ((phase->type(address)->isa_oopptr() || phase->type(address)->isa_narrowoop()) &&
1526 phase->type(address)->is_ptr()->offset() == oopDesc::mark_offset_in_bytes());
1527
1528 // Skip up past a SafePoint control. Cannot do this for Stores because
1529 // pointer stores & cardmarks must stay on the same side of a SafePoint.
1530 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint &&
1531 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw &&
1532 !addr_mark ) {
1533 ctrl = ctrl->in(0);
1534 set_req(MemNode::Control,ctrl);
1535 }
1536
1537 intptr_t ignore = 0;
1538 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1539 if (base != NULL
1540 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
1541 // Check for useless control edge in some common special cases
1542 if (in(MemNode::Control) != NULL
1543 && can_remove_control()
1544 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1545 && all_controls_dominate(base, phase->C->start())) {
1546 // A method-invariant, non-null address (constant or 'this' argument).
1547 set_req(MemNode::Control, NULL);
1548 }
1549 }
1550
1551 Node* mem = in(MemNode::Memory);
1552 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1553
1554 if (can_reshape && (addr_t != NULL)) {
1555 // try to optimize our memory input
1556 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase);
1557 if (opt_mem != mem) {
1558 set_req(MemNode::Memory, opt_mem);
1559 if (phase->type( opt_mem ) == Type::TOP) return NULL;
1560 return this;
1561 }
1562 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1563 if ((t_oop != NULL) &&
1564 (t_oop->is_known_instance_field() ||
1565 t_oop->is_ptr_to_boxed_value())) {
1566 PhaseIterGVN *igvn = phase->is_IterGVN();
1567 if (igvn != NULL && igvn->_worklist.member(opt_mem)) {
1568 // Delay this transformation until memory Phi is processed.
1569 phase->is_IterGVN()->_worklist.push(this);
1570 return NULL;
1571 }
1572 // Split instance field load through Phi.
1573 Node* result = split_through_phi(phase);
1574 if (result != NULL) return result;
1575
1576 if (t_oop->is_ptr_to_boxed_value()) {
1577 Node* result = eliminate_autobox(phase);
1578 if (result != NULL) return result;
1579 }
1580 }
1581 }
1582
1583 // Check for prior store with a different base or offset; make Load
1584 // independent. Skip through any number of them. Bail out if the stores
1585 // are in an endless dead cycle and report no progress. This is a key
1586 // transform for Reflection. However, if after skipping through the Stores
1587 // we can't then fold up against a prior store do NOT do the transform as
1588 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
1589 // array memory alive twice: once for the hoisted Load and again after the
1590 // bypassed Store. This situation only works if EVERYBODY who does
1591 // anti-dependence work knows how to bypass. I.e. we need all
1592 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
1593 // the alias index stuff. So instead, peek through Stores and IFF we can
1594 // fold up, do so.
1595 Node* prev_mem = find_previous_store(phase);
1596 // Steps (a), (b): Walk past independent stores to find an exact match.
1597 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) {
1598 // (c) See if we can fold up on the spot, but don't fold up here.
1599 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
1600 // just return a prior value, which is done by Identity calls.
1601 if (can_see_stored_value(prev_mem, phase)) {
1602 // Make ready for step (d):
1603 set_req(MemNode::Memory, prev_mem);
1604 return this;
1605 }
1606 }
1607
1608 return NULL; // No further progress
1609 }
1610
1611 // Helper to recognize certain Klass fields which are invariant across
1612 // some group of array types (e.g., int[] or all T[] where T < Object).
1613 const Type*
1614 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1615 ciKlass* klass) const {
1616 if (tkls->offset() == in_bytes(Klass::modifier_flags_offset())) {
1617 // The field is Klass::_modifier_flags. Return its (constant) value.
1618 // (Folds up the 2nd indirection in aClassConstant.getModifiers().)
1619 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags");
1620 return TypeInt::make(klass->modifier_flags());
1621 }
1622 if (tkls->offset() == in_bytes(Klass::access_flags_offset())) {
1623 // The field is Klass::_access_flags. Return its (constant) value.
1624 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1625 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags");
1626 return TypeInt::make(klass->access_flags());
1627 }
1628 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) {
1629 // The field is Klass::_layout_helper. Return its constant value if known.
1630 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper");
1631 return TypeInt::make(klass->layout_helper());
1632 }
1633
1634 // No match.
1635 return NULL;
1636 }
1637
1638 // Try to constant-fold a stable array element.
1639 static const Type* fold_stable_ary_elem(const TypeAryPtr* ary, int off, BasicType loadbt) {
1640 assert(ary->const_oop(), "array should be constant");
1641 assert(ary->is_stable(), "array should be stable");
1642
1643 // Decode the results of GraphKit::array_element_address.
1644 ciArray* aobj = ary->const_oop()->as_array();
1645 ciConstant con = aobj->element_value_by_offset(off);
1646
1647 if (con.basic_type() != T_ILLEGAL && !con.is_null_or_zero()) {
1648 const Type* con_type = Type::make_from_constant(con);
1649 if (con_type != NULL) {
1650 if (con_type->isa_aryptr()) {
1651 // Join with the array element type, in case it is also stable.
1652 int dim = ary->stable_dimension();
1653 con_type = con_type->is_aryptr()->cast_to_stable(true, dim-1);
1654 }
1655 if (loadbt == T_NARROWOOP && con_type->isa_oopptr()) {
1656 con_type = con_type->make_narrowoop();
1657 }
1658 #ifndef PRODUCT
1659 if (TraceIterativeGVN) {
1660 tty->print("FoldStableValues: array element [off=%d]: con_type=", off);
1661 con_type->dump(); tty->cr();
1662 }
1663 #endif //PRODUCT
1664 return con_type;
1665 }
1666 }
1667 return NULL;
1668 }
1669
1670 //------------------------------Value-----------------------------------------
1671 const Type *LoadNode::Value( PhaseTransform *phase ) const {
1672 // Either input is TOP ==> the result is TOP
1673 Node* mem = in(MemNode::Memory);
1674 const Type *t1 = phase->type(mem);
1675 if (t1 == Type::TOP) return Type::TOP;
1676 Node* adr = in(MemNode::Address);
1677 const TypePtr* tp = phase->type(adr)->isa_ptr();
1678 if (tp == NULL || tp->empty()) return Type::TOP;
1679 int off = tp->offset();
1680 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
1681 Compile* C = phase->C;
1682
1683 // Try to guess loaded type from pointer type
1684 if (tp->isa_aryptr()) {
1685 const TypeAryPtr* ary = tp->is_aryptr();
1686 const Type* t = ary->elem();
1687
1688 // Determine whether the reference is beyond the header or not, by comparing
1689 // the offset against the offset of the start of the array's data.
1690 // Different array types begin at slightly different offsets (12 vs. 16).
1691 // We choose T_BYTE as an example base type that is least restrictive
1692 // as to alignment, which will therefore produce the smallest
1693 // possible base offset.
1694 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
1695 const bool off_beyond_header = ((uint)off >= (uint)min_base_off);
1696
1697 // Try to constant-fold a stable array element.
1698 if (FoldStableValues && ary->is_stable() && ary->const_oop() != NULL) {
1699 // Make sure the reference is not into the header and the offset is constant
1700 if (off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) {
1701 const Type* con_type = fold_stable_ary_elem(ary, off, memory_type());
1702 if (con_type != NULL) {
1703 return con_type;
1704 }
1705 }
1706 }
1707
1708 // Don't do this for integer types. There is only potential profit if
1709 // the element type t is lower than _type; that is, for int types, if _type is
1710 // more restrictive than t. This only happens here if one is short and the other
1711 // char (both 16 bits), and in those cases we've made an intentional decision
1712 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
1713 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
1714 //
1715 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
1716 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
1717 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
1718 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
1719 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
1720 // In fact, that could have been the original type of p1, and p1 could have
1721 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
1722 // expression (LShiftL quux 3) independently optimized to the constant 8.
1723 if ((t->isa_int() == NULL) && (t->isa_long() == NULL)
1724 && (_type->isa_vect() == NULL)
1725 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
1726 // t might actually be lower than _type, if _type is a unique
1727 // concrete subclass of abstract class t.
1728 if (off_beyond_header) { // is the offset beyond the header?
1729 const Type* jt = t->join_speculative(_type);
1730 // In any case, do not allow the join, per se, to empty out the type.
1731 if (jt->empty() && !t->empty()) {
1732 // This can happen if a interface-typed array narrows to a class type.
1733 jt = _type;
1734 }
1735 #ifdef ASSERT
1736 if (phase->C->eliminate_boxing() && adr->is_AddP()) {
1737 // The pointers in the autobox arrays are always non-null
1738 Node* base = adr->in(AddPNode::Base);
1739 if ((base != NULL) && base->is_DecodeN()) {
1740 // Get LoadN node which loads IntegerCache.cache field
1741 base = base->in(1);
1742 }
1743 if ((base != NULL) && base->is_Con()) {
1744 const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr();
1745 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1746 // It could be narrow oop
1747 assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity");
1748 }
1749 }
1750 }
1751 #endif
1752 return jt;
1753 }
1754 }
1755 } else if (tp->base() == Type::InstPtr) {
1756 ciEnv* env = C->env();
1757 const TypeInstPtr* tinst = tp->is_instptr();
1758 ciKlass* klass = tinst->klass();
1759 assert( off != Type::OffsetBot ||
1760 // arrays can be cast to Objects
1761 tp->is_oopptr()->klass()->is_java_lang_Object() ||
1762 // unsafe field access may not have a constant offset
1763 C->has_unsafe_access(),
1764 "Field accesses must be precise" );
1765 // For oop loads, we expect the _type to be precise
1766 if (klass == env->String_klass() &&
1767 adr->is_AddP() && off != Type::OffsetBot) {
1768 // For constant Strings treat the final fields as compile time constants.
1769 Node* base = adr->in(AddPNode::Base);
1770 const TypeOopPtr* t = phase->type(base)->isa_oopptr();
1771 if (t != NULL && t->singleton()) {
1772 ciField* field = env->String_klass()->get_field_by_offset(off, false);
1773 if (field != NULL && field->is_final()) {
1774 ciObject* string = t->const_oop();
1775 ciConstant constant = string->as_instance()->field_value(field);
1776 if (constant.basic_type() == T_INT) {
1777 return TypeInt::make(constant.as_int());
1778 } else if (constant.basic_type() == T_ARRAY) {
1779 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
1780 return TypeNarrowOop::make_from_constant(constant.as_object(), true);
1781 } else {
1782 return TypeOopPtr::make_from_constant(constant.as_object(), true);
1783 }
1784 }
1785 }
1786 }
1787 }
1788 // Optimizations for constant objects
1789 ciObject* const_oop = tinst->const_oop();
1790 if (const_oop != NULL) {
1791 // For constant Boxed value treat the target field as a compile time constant.
1792 if (tinst->is_ptr_to_boxed_value()) {
1793 return tinst->get_const_boxed_value();
1794 } else
1795 // For constant CallSites treat the target field as a compile time constant.
1796 if (const_oop->is_call_site()) {
1797 ciCallSite* call_site = const_oop->as_call_site();
1798 ciField* field = call_site->klass()->as_instance_klass()->get_field_by_offset(off, /*is_static=*/ false);
1799 if (field != NULL && field->is_call_site_target()) {
1800 ciMethodHandle* target = call_site->get_target();
1801 if (target != NULL) { // just in case
1802 ciConstant constant(T_OBJECT, target);
1803 const Type* t;
1804 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
1805 t = TypeNarrowOop::make_from_constant(constant.as_object(), true);
1806 } else {
1807 t = TypeOopPtr::make_from_constant(constant.as_object(), true);
1808 }
1809 // Add a dependence for invalidation of the optimization.
1810 if (!call_site->is_constant_call_site()) {
1811 C->dependencies()->assert_call_site_target_value(call_site, target);
1812 }
1813 return t;
1814 }
1815 }
1816 }
1817 }
1818 } else if (tp->base() == Type::KlassPtr) {
1819 assert( off != Type::OffsetBot ||
1820 // arrays can be cast to Objects
1821 tp->is_klassptr()->klass()->is_java_lang_Object() ||
1822 // also allow array-loading from the primary supertype
1823 // array during subtype checks
1824 Opcode() == Op_LoadKlass,
1825 "Field accesses must be precise" );
1826 // For klass/static loads, we expect the _type to be precise
1827 }
1828
1829 const TypeKlassPtr *tkls = tp->isa_klassptr();
1830 if (tkls != NULL && !StressReflectiveCode) {
1831 ciKlass* klass = tkls->klass();
1832 if (klass->is_loaded() && tkls->klass_is_exact()) {
1833 // We are loading a field from a Klass metaobject whose identity
1834 // is known at compile time (the type is "exact" or "precise").
1835 // Check for fields we know are maintained as constants by the VM.
1836 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) {
1837 // The field is Klass::_super_check_offset. Return its (constant) value.
1838 // (Folds up type checking code.)
1839 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
1840 return TypeInt::make(klass->super_check_offset());
1841 }
1842 // Compute index into primary_supers array
1843 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1844 // Check for overflowing; use unsigned compare to handle the negative case.
1845 if( depth < ciKlass::primary_super_limit() ) {
1846 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1847 // (Folds up type checking code.)
1848 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1849 ciKlass *ss = klass->super_of_depth(depth);
1850 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1851 }
1852 const Type* aift = load_array_final_field(tkls, klass);
1853 if (aift != NULL) return aift;
1854 if (tkls->offset() == in_bytes(ArrayKlass::component_mirror_offset())
1855 && klass->is_array_klass()) {
1856 // The field is ArrayKlass::_component_mirror. Return its (constant) value.
1857 // (Folds up aClassConstant.getComponentType, common in Arrays.copyOf.)
1858 assert(Opcode() == Op_LoadP, "must load an oop from _component_mirror");
1859 return TypeInstPtr::make(klass->as_array_klass()->component_mirror());
1860 }
1861 if (tkls->offset() == in_bytes(Klass::java_mirror_offset())) {
1862 // The field is Klass::_java_mirror. Return its (constant) value.
1863 // (Folds up the 2nd indirection in anObjConstant.getClass().)
1864 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
1865 return TypeInstPtr::make(klass->java_mirror());
1866 }
1867 }
1868
1869 // We can still check if we are loading from the primary_supers array at a
1870 // shallow enough depth. Even though the klass is not exact, entries less
1871 // than or equal to its super depth are correct.
1872 if (klass->is_loaded() ) {
1873 ciType *inner = klass;
1874 while( inner->is_obj_array_klass() )
1875 inner = inner->as_obj_array_klass()->base_element_type();
1876 if( inner->is_instance_klass() &&
1877 !inner->as_instance_klass()->flags().is_interface() ) {
1878 // Compute index into primary_supers array
1879 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1880 // Check for overflowing; use unsigned compare to handle the negative case.
1881 if( depth < ciKlass::primary_super_limit() &&
1882 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case
1883 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1884 // (Folds up type checking code.)
1885 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1886 ciKlass *ss = klass->super_of_depth(depth);
1887 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1888 }
1889 }
1890 }
1891
1892 // If the type is enough to determine that the thing is not an array,
1893 // we can give the layout_helper a positive interval type.
1894 // This will help short-circuit some reflective code.
1895 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())
1896 && !klass->is_array_klass() // not directly typed as an array
1897 && !klass->is_interface() // specifically not Serializable & Cloneable
1898 && !klass->is_java_lang_Object() // not the supertype of all T[]
1899 ) {
1900 // Note: When interfaces are reliable, we can narrow the interface
1901 // test to (klass != Serializable && klass != Cloneable).
1902 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
1903 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
1904 // The key property of this type is that it folds up tests
1905 // for array-ness, since it proves that the layout_helper is positive.
1906 // Thus, a generic value like the basic object layout helper works fine.
1907 return TypeInt::make(min_size, max_jint, Type::WidenMin);
1908 }
1909 }
1910
1911 // If we are loading from a freshly-allocated object, produce a zero,
1912 // if the load is provably beyond the header of the object.
1913 // (Also allow a variable load from a fresh array to produce zero.)
1914 const TypeOopPtr *tinst = tp->isa_oopptr();
1915 bool is_instance = (tinst != NULL) && tinst->is_known_instance_field();
1916 bool is_boxed_value = (tinst != NULL) && tinst->is_ptr_to_boxed_value();
1917 if (ReduceFieldZeroing || is_instance || is_boxed_value) {
1918 Node* value = can_see_stored_value(mem,phase);
1919 if (value != NULL && value->is_Con()) {
1920 assert(value->bottom_type()->higher_equal(_type),"sanity");
1921 return value->bottom_type();
1922 }
1923 }
1924
1925 if (is_instance) {
1926 // If we have an instance type and our memory input is the
1927 // programs's initial memory state, there is no matching store,
1928 // so just return a zero of the appropriate type
1929 Node *mem = in(MemNode::Memory);
1930 if (mem->is_Parm() && mem->in(0)->is_Start()) {
1931 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
1932 return Type::get_zero_type(_type->basic_type());
1933 }
1934 }
1935 return _type;
1936 }
1937
1938 //------------------------------match_edge-------------------------------------
1939 // Do we Match on this edge index or not? Match only the address.
1940 uint LoadNode::match_edge(uint idx) const {
1941 return idx == MemNode::Address;
1942 }
1943
1944 //--------------------------LoadBNode::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 *LoadBNode::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 Node *result = phase->transform( new (phase->C) LShiftINode(value, phase->intcon(24)) );
1956 return new (phase->C) RShiftINode(result, phase->intcon(24));
1957 }
1958 // Identity call will handle the case where truncation is not needed.
1959 return LoadNode::Ideal(phase, can_reshape);
1960 }
1961
1962 const Type* LoadBNode::Value(PhaseTransform *phase) const {
1963 Node* mem = in(MemNode::Memory);
1964 Node* value = can_see_stored_value(mem,phase);
1965 if (value != NULL && value->is_Con() &&
1966 !value->bottom_type()->higher_equal(_type)) {
1967 // If the input to the store does not fit with the load's result type,
1968 // it must be truncated. We can't delay until Ideal call since
1969 // a singleton Value is needed for split_thru_phi optimization.
1970 int con = value->get_int();
1971 return TypeInt::make((con << 24) >> 24);
1972 }
1973 return LoadNode::Value(phase);
1974 }
1975
1976 //--------------------------LoadUBNode::Ideal-------------------------------------
1977 //
1978 // If the previous store is to the same address as this load,
1979 // and the value stored was larger than a byte, replace this load
1980 // with the value stored truncated to a byte. If no truncation is
1981 // needed, the replacement is done in LoadNode::Identity().
1982 //
1983 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
1984 Node* mem = in(MemNode::Memory);
1985 Node* value = can_see_stored_value(mem, phase);
1986 if (value && !phase->type(value)->higher_equal(_type))
1987 return new (phase->C) AndINode(value, phase->intcon(0xFF));
1988 // Identity call will handle the case where truncation is not needed.
1989 return LoadNode::Ideal(phase, can_reshape);
1990 }
1991
1992 const Type* LoadUBNode::Value(PhaseTransform *phase) const {
1993 Node* mem = in(MemNode::Memory);
1994 Node* value = can_see_stored_value(mem,phase);
1995 if (value != NULL && value->is_Con() &&
1996 !value->bottom_type()->higher_equal(_type)) {
1997 // If the input to the store does not fit with the load's result type,
1998 // it must be truncated. We can't delay until Ideal call since
1999 // a singleton Value is needed for split_thru_phi optimization.
2000 int con = value->get_int();
2001 return TypeInt::make(con & 0xFF);
2002 }
2003 return LoadNode::Value(phase);
2004 }
2005
2006 //--------------------------LoadUSNode::Ideal-------------------------------------
2007 //
2008 // If the previous store is to the same address as this load,
2009 // and the value stored was larger than a char, replace this load
2010 // with the value stored truncated to a char. If no truncation is
2011 // needed, the replacement is done in LoadNode::Identity().
2012 //
2013 Node *LoadUSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2014 Node* mem = in(MemNode::Memory);
2015 Node* value = can_see_stored_value(mem,phase);
2016 if( value && !phase->type(value)->higher_equal( _type ) )
2017 return new (phase->C) AndINode(value,phase->intcon(0xFFFF));
2018 // Identity call will handle the case where truncation is not needed.
2019 return LoadNode::Ideal(phase, can_reshape);
2020 }
2021
2022 const Type* LoadUSNode::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 & 0xFFFF);
2032 }
2033 return LoadNode::Value(phase);
2034 }
2035
2036 //--------------------------LoadSNode::Ideal--------------------------------------
2037 //
2038 // If the previous store is to the same address as this load,
2039 // and the value stored was larger than a short, replace this load
2040 // with the value stored truncated to a short. If no truncation is
2041 // needed, the replacement is done in LoadNode::Identity().
2042 //
2043 Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2044 Node* mem = in(MemNode::Memory);
2045 Node* value = can_see_stored_value(mem,phase);
2046 if( value && !phase->type(value)->higher_equal( _type ) ) {
2047 Node *result = phase->transform( new (phase->C) LShiftINode(value, phase->intcon(16)) );
2048 return new (phase->C) RShiftINode(result, phase->intcon(16));
2049 }
2050 // Identity call will handle the case where truncation is not needed.
2051 return LoadNode::Ideal(phase, can_reshape);
2052 }
2053
2054 const Type* LoadSNode::Value(PhaseTransform *phase) const {
2055 Node* mem = in(MemNode::Memory);
2056 Node* value = can_see_stored_value(mem,phase);
2057 if (value != NULL && value->is_Con() &&
2058 !value->bottom_type()->higher_equal(_type)) {
2059 // If the input to the store does not fit with the load's result type,
2060 // it must be truncated. We can't delay until Ideal call since
2061 // a singleton Value is needed for split_thru_phi optimization.
2062 int con = value->get_int();
2063 return TypeInt::make((con << 16) >> 16);
2064 }
2065 return LoadNode::Value(phase);
2066 }
2067
2068 //=============================================================================
2069 //----------------------------LoadKlassNode::make------------------------------
2070 // Polymorphic factory method:
2071 Node* LoadKlassNode::make(PhaseGVN& gvn, Node* ctl, Node *mem, Node *adr, const TypePtr* at, const TypeKlassPtr *tk) {
2072 Compile* C = gvn.C;
2073 // sanity check the alias category against the created node type
2074 const TypePtr *adr_type = adr->bottom_type()->isa_ptr();
2075 assert(adr_type != NULL, "expecting TypeKlassPtr");
2076 #ifdef _LP64
2077 if (adr_type->is_ptr_to_narrowklass()) {
2078 assert(UseCompressedClassPointers, "no compressed klasses");
2079 Node* load_klass = gvn.transform(new (C) LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowklass(), MemNode::unordered));
2080 return new (C) DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr());
2081 }
2082 #endif
2083 assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
2084 return new (C) LoadKlassNode(ctl, mem, adr, at, tk, MemNode::unordered);
2085 }
2086
2087 //------------------------------Value------------------------------------------
2088 const Type *LoadKlassNode::Value( PhaseTransform *phase ) const {
2089 return klass_value_common(phase);
2090 }
2091
2092 // In most cases, LoadKlassNode does not have the control input set. If the control
2093 // input is set, it must not be removed (by LoadNode::Ideal()).
2094 bool LoadKlassNode::can_remove_control() const {
2095 return false;
2096 }
2097
2098 const Type *LoadNode::klass_value_common( PhaseTransform *phase ) const {
2099 // Either input is TOP ==> the result is TOP
2100 const Type *t1 = phase->type( in(MemNode::Memory) );
2101 if (t1 == Type::TOP) return Type::TOP;
2102 Node *adr = in(MemNode::Address);
2103 const Type *t2 = phase->type( adr );
2104 if (t2 == Type::TOP) return Type::TOP;
2105 const TypePtr *tp = t2->is_ptr();
2106 if (TypePtr::above_centerline(tp->ptr()) ||
2107 tp->ptr() == TypePtr::Null) return Type::TOP;
2108
2109 // Return a more precise klass, if possible
2110 const TypeInstPtr *tinst = tp->isa_instptr();
2111 if (tinst != NULL) {
2112 ciInstanceKlass* ik = tinst->klass()->as_instance_klass();
2113 int offset = tinst->offset();
2114 if (ik == phase->C->env()->Class_klass()
2115 && (offset == java_lang_Class::klass_offset_in_bytes() ||
2116 offset == java_lang_Class::array_klass_offset_in_bytes())) {
2117 // We are loading a special hidden field from a Class mirror object,
2118 // the field which points to the VM's Klass metaobject.
2119 ciType* t = tinst->java_mirror_type();
2120 // java_mirror_type returns non-null for compile-time Class constants.
2121 if (t != NULL) {
2122 // constant oop => constant klass
2123 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
2124 if (t->is_void()) {
2125 // We cannot create a void array. Since void is a primitive type return null
2126 // klass. Users of this result need to do a null check on the returned klass.
2127 return TypePtr::NULL_PTR;
2128 }
2129 return TypeKlassPtr::make(ciArrayKlass::make(t));
2130 }
2131 if (!t->is_klass()) {
2132 // a primitive Class (e.g., int.class) has NULL for a klass field
2133 return TypePtr::NULL_PTR;
2134 }
2135 // (Folds up the 1st indirection in aClassConstant.getModifiers().)
2136 return TypeKlassPtr::make(t->as_klass());
2137 }
2138 // non-constant mirror, so we can't tell what's going on
2139 }
2140 if( !ik->is_loaded() )
2141 return _type; // Bail out if not loaded
2142 if (offset == oopDesc::klass_offset_in_bytes()) {
2143 if (tinst->klass_is_exact()) {
2144 return TypeKlassPtr::make(ik);
2145 }
2146 // See if we can become precise: no subklasses and no interface
2147 // (Note: We need to support verified interfaces.)
2148 if (!ik->is_interface() && !ik->has_subklass()) {
2149 //assert(!UseExactTypes, "this code should be useless with exact types");
2150 // Add a dependence; if any subclass added we need to recompile
2151 if (!ik->is_final()) {
2152 // %%% should use stronger assert_unique_concrete_subtype instead
2153 phase->C->dependencies()->assert_leaf_type(ik);
2154 }
2155 // Return precise klass
2156 return TypeKlassPtr::make(ik);
2157 }
2158
2159 // Return root of possible klass
2160 return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/);
2161 }
2162 }
2163
2164 // Check for loading klass from an array
2165 const TypeAryPtr *tary = tp->isa_aryptr();
2166 if( tary != NULL ) {
2167 ciKlass *tary_klass = tary->klass();
2168 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP
2169 && tary->offset() == oopDesc::klass_offset_in_bytes()) {
2170 if (tary->klass_is_exact()) {
2171 return TypeKlassPtr::make(tary_klass);
2172 }
2173 ciArrayKlass *ak = tary->klass()->as_array_klass();
2174 // If the klass is an object array, we defer the question to the
2175 // array component klass.
2176 if( ak->is_obj_array_klass() ) {
2177 assert( ak->is_loaded(), "" );
2178 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass();
2179 if( base_k->is_loaded() && base_k->is_instance_klass() ) {
2180 ciInstanceKlass* ik = base_k->as_instance_klass();
2181 // See if we can become precise: no subklasses and no interface
2182 if (!ik->is_interface() && !ik->has_subklass()) {
2183 //assert(!UseExactTypes, "this code should be useless with exact types");
2184 // Add a dependence; if any subclass added we need to recompile
2185 if (!ik->is_final()) {
2186 phase->C->dependencies()->assert_leaf_type(ik);
2187 }
2188 // Return precise array klass
2189 return TypeKlassPtr::make(ak);
2190 }
2191 }
2192 return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/);
2193 } else { // Found a type-array?
2194 //assert(!UseExactTypes, "this code should be useless with exact types");
2195 assert( ak->is_type_array_klass(), "" );
2196 return TypeKlassPtr::make(ak); // These are always precise
2197 }
2198 }
2199 }
2200
2201 // Check for loading klass from an array klass
2202 const TypeKlassPtr *tkls = tp->isa_klassptr();
2203 if (tkls != NULL && !StressReflectiveCode) {
2204 ciKlass* klass = tkls->klass();
2205 if( !klass->is_loaded() )
2206 return _type; // Bail out if not loaded
2207 if( klass->is_obj_array_klass() &&
2208 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) {
2209 ciKlass* elem = klass->as_obj_array_klass()->element_klass();
2210 // // Always returning precise element type is incorrect,
2211 // // e.g., element type could be object and array may contain strings
2212 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
2213
2214 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
2215 // according to the element type's subclassing.
2216 return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/);
2217 }
2218 if( klass->is_instance_klass() && tkls->klass_is_exact() &&
2219 tkls->offset() == in_bytes(Klass::super_offset())) {
2220 ciKlass* sup = klass->as_instance_klass()->super();
2221 // The field is Klass::_super. Return its (constant) value.
2222 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
2223 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR;
2224 }
2225 }
2226
2227 // Bailout case
2228 return LoadNode::Value(phase);
2229 }
2230
2231 //------------------------------Identity---------------------------------------
2232 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
2233 // Also feed through the klass in Allocate(...klass...)._klass.
2234 Node* LoadKlassNode::Identity( PhaseTransform *phase ) {
2235 return klass_identity_common(phase);
2236 }
2237
2238 Node* LoadNode::klass_identity_common(PhaseTransform *phase ) {
2239 Node* x = LoadNode::Identity(phase);
2240 if (x != this) return x;
2241
2242 // Take apart the address into an oop and and offset.
2243 // Return 'this' if we cannot.
2244 Node* adr = in(MemNode::Address);
2245 intptr_t offset = 0;
2246 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2247 if (base == NULL) return this;
2248 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
2249 if (toop == NULL) return this;
2250
2251 // We can fetch the klass directly through an AllocateNode.
2252 // This works even if the klass is not constant (clone or newArray).
2253 if (offset == oopDesc::klass_offset_in_bytes()) {
2254 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
2255 if (allocated_klass != NULL) {
2256 return allocated_klass;
2257 }
2258 }
2259
2260 // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*.
2261 // Simplify ak.component_mirror.array_klass to plain ak, ak an ArrayKlass.
2262 // See inline_native_Class_query for occurrences of these patterns.
2263 // Java Example: x.getClass().isAssignableFrom(y)
2264 // Java Example: Array.newInstance(x.getClass().getComponentType(), n)
2265 //
2266 // This improves reflective code, often making the Class
2267 // mirror go completely dead. (Current exception: Class
2268 // mirrors may appear in debug info, but we could clean them out by
2269 // introducing a new debug info operator for Klass*.java_mirror).
2270 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass()
2271 && (offset == java_lang_Class::klass_offset_in_bytes() ||
2272 offset == java_lang_Class::array_klass_offset_in_bytes())) {
2273 // We are loading a special hidden field from a Class mirror,
2274 // the field which points to its Klass or ArrayKlass metaobject.
2275 if (base->is_Load()) {
2276 Node* adr2 = base->in(MemNode::Address);
2277 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2278 if (tkls != NULL && !tkls->empty()
2279 && (tkls->klass()->is_instance_klass() ||
2280 tkls->klass()->is_array_klass())
2281 && adr2->is_AddP()
2282 ) {
2283 int mirror_field = in_bytes(Klass::java_mirror_offset());
2284 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
2285 mirror_field = in_bytes(ArrayKlass::component_mirror_offset());
2286 }
2287 if (tkls->offset() == mirror_field) {
2288 return adr2->in(AddPNode::Base);
2289 }
2290 }
2291 }
2292 }
2293
2294 return this;
2295 }
2296
2297
2298 //------------------------------Value------------------------------------------
2299 const Type *LoadNKlassNode::Value( PhaseTransform *phase ) const {
2300 const Type *t = klass_value_common(phase);
2301 if (t == Type::TOP)
2302 return t;
2303
2304 return t->make_narrowklass();
2305 }
2306
2307 //------------------------------Identity---------------------------------------
2308 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
2309 // Also feed through the klass in Allocate(...klass...)._klass.
2310 Node* LoadNKlassNode::Identity( PhaseTransform *phase ) {
2311 Node *x = klass_identity_common(phase);
2312
2313 const Type *t = phase->type( x );
2314 if( t == Type::TOP ) return x;
2315 if( t->isa_narrowklass()) return x;
2316 assert (!t->isa_narrowoop(), "no narrow oop here");
2317
2318 return phase->transform(new (phase->C) EncodePKlassNode(x, t->make_narrowklass()));
2319 }
2320
2321 //------------------------------Value-----------------------------------------
2322 const Type *LoadRangeNode::Value( PhaseTransform *phase ) const {
2323 // Either input is TOP ==> the result is TOP
2324 const Type *t1 = phase->type( in(MemNode::Memory) );
2325 if( t1 == Type::TOP ) return Type::TOP;
2326 Node *adr = in(MemNode::Address);
2327 const Type *t2 = phase->type( adr );
2328 if( t2 == Type::TOP ) return Type::TOP;
2329 const TypePtr *tp = t2->is_ptr();
2330 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
2331 const TypeAryPtr *tap = tp->isa_aryptr();
2332 if( !tap ) return _type;
2333 return tap->size();
2334 }
2335
2336 //-------------------------------Ideal---------------------------------------
2337 // Feed through the length in AllocateArray(...length...)._length.
2338 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2339 Node* p = MemNode::Ideal_common(phase, can_reshape);
2340 if (p) return (p == NodeSentinel) ? NULL : p;
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 NULL;
2348 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2349 if (tary == NULL) return NULL;
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 Node* len = alloc->make_ideal_length(tary, phase);
2358 if (allocated_length != len) {
2359 // New CastII improves on this.
2360 return len;
2361 }
2362 }
2363 }
2364
2365 return NULL;
2366 }
2367
2368 //------------------------------Identity---------------------------------------
2369 // Feed through the length in AllocateArray(...length...)._length.
2370 Node* LoadRangeNode::Identity( PhaseTransform *phase ) {
2371 Node* x = LoadINode::Identity(phase);
2372 if (x != this) return x;
2373
2374 // Take apart the address into an oop and and offset.
2375 // Return 'this' if we cannot.
2376 Node* adr = in(MemNode::Address);
2377 intptr_t offset = 0;
2378 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2379 if (base == NULL) return this;
2380 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2381 if (tary == NULL) return this;
2382
2383 // We can fetch the length directly through an AllocateArrayNode.
2384 // This works even if the length is not constant (clone or newArray).
2385 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2386 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2387 if (alloc != NULL) {
2388 Node* allocated_length = alloc->Ideal_length();
2389 // Do not allow make_ideal_length to allocate a CastII node.
2390 Node* len = alloc->make_ideal_length(tary, phase, false);
2391 if (allocated_length == len) {
2392 // Return allocated_length only if it would not be improved by a CastII.
2393 return allocated_length;
2394 }
2395 }
2396 }
2397
2398 return this;
2399
2400 }
2401
2402 //=============================================================================
2403 //---------------------------StoreNode::make-----------------------------------
2404 // Polymorphic factory method:
2405 StoreNode* StoreNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt, MemOrd mo) {
2406 assert((mo == unordered || mo == release), "unexpected");
2407 Compile* C = gvn.C;
2408 assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2409 ctl != NULL, "raw memory operations should have control edge");
2410
2411 switch (bt) {
2412 case T_BOOLEAN: val = gvn.transform(new (C) AndINode(val, gvn.intcon(0x1))); // Fall through to T_BYTE case
2413 case T_BYTE: return new (C) StoreBNode(ctl, mem, adr, adr_type, val, mo);
2414 case T_INT: return new (C) StoreINode(ctl, mem, adr, adr_type, val, mo);
2415 case T_CHAR:
2416 case T_SHORT: return new (C) StoreCNode(ctl, mem, adr, adr_type, val, mo);
2417 case T_LONG: return new (C) StoreLNode(ctl, mem, adr, adr_type, val, mo);
2418 case T_FLOAT: return new (C) StoreFNode(ctl, mem, adr, adr_type, val, mo);
2419 case T_DOUBLE: return new (C) StoreDNode(ctl, mem, adr, adr_type, val, mo);
2420 case T_METADATA:
2421 case T_ADDRESS:
2422 case T_OBJECT:
2423 #ifdef _LP64
2424 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
2425 val = gvn.transform(new (C) EncodePNode(val, val->bottom_type()->make_narrowoop()));
2426 return new (C) StoreNNode(ctl, mem, adr, adr_type, val, mo);
2427 } else if (adr->bottom_type()->is_ptr_to_narrowklass() ||
2428 (UseCompressedClassPointers && val->bottom_type()->isa_klassptr() &&
2429 adr->bottom_type()->isa_rawptr())) {
2430 val = gvn.transform(new (C) EncodePKlassNode(val, val->bottom_type()->make_narrowklass()));
2431 return new (C) StoreNKlassNode(ctl, mem, adr, adr_type, val, mo);
2432 }
2433 #endif
2434 {
2435 return new (C) StorePNode(ctl, mem, adr, adr_type, val, mo);
2436 }
2437 }
2438 ShouldNotReachHere();
2439 return (StoreNode*)NULL;
2440 }
2441
2442 StoreLNode* StoreLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
2443 bool require_atomic = true;
2444 return new (C) StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
2445 }
2446
2447 StoreDNode* StoreDNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
2448 bool require_atomic = true;
2449 return new (C) StoreDNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
2450 }
2451
2452
2453 //--------------------------bottom_type----------------------------------------
2454 const Type *StoreNode::bottom_type() const {
2455 return Type::MEMORY;
2456 }
2457
2458 //------------------------------hash-------------------------------------------
2459 uint StoreNode::hash() const {
2460 // unroll addition of interesting fields
2461 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2462
2463 // Since they are not commoned, do not hash them:
2464 return NO_HASH;
2465 }
2466
2467 //------------------------------Ideal------------------------------------------
2468 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
2469 // When a store immediately follows a relevant allocation/initialization,
2470 // try to capture it into the initialization, or hoist it above.
2471 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2472 Node* p = MemNode::Ideal_common(phase, can_reshape);
2473 if (p) return (p == NodeSentinel) ? NULL : p;
2474
2475 Node* mem = in(MemNode::Memory);
2476 Node* address = in(MemNode::Address);
2477
2478 // Back-to-back stores to same address? Fold em up. Generally
2479 // unsafe if I have intervening uses... Also disallowed for StoreCM
2480 // since they must follow each StoreP operation. Redundant StoreCMs
2481 // are eliminated just before matching in final_graph_reshape.
2482 if (mem->is_Store() && mem->in(MemNode::Address)->eqv_uncast(address) &&
2483 mem->Opcode() != Op_StoreCM) {
2484 // Looking at a dead closed cycle of memory?
2485 assert(mem != mem->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
2486
2487 assert(Opcode() == mem->Opcode() ||
2488 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw ||
2489 (is_mismatched_access() || mem->as_Store()->is_mismatched_access()),
2490 "no mismatched stores, except on raw memory");
2491
2492 if (mem->outcnt() == 1 && // check for intervening uses
2493 mem->as_Store()->memory_size() <= this->memory_size()) {
2494 // If anybody other than 'this' uses 'mem', we cannot fold 'mem' away.
2495 // For example, 'mem' might be the final state at a conditional return.
2496 // Or, 'mem' might be used by some node which is live at the same time
2497 // 'this' is live, which might be unschedulable. So, require exactly
2498 // ONE user, the 'this' store, until such time as we clone 'mem' for
2499 // each of 'mem's uses (thus making the exactly-1-user-rule hold true).
2500 if (can_reshape) { // (%%% is this an anachronism?)
2501 set_req_X(MemNode::Memory, mem->in(MemNode::Memory),
2502 phase->is_IterGVN());
2503 } else {
2504 // It's OK to do this in the parser, since DU info is always accurate,
2505 // and the parser always refers to nodes via SafePointNode maps.
2506 set_req(MemNode::Memory, mem->in(MemNode::Memory));
2507 }
2508 return this;
2509 }
2510 }
2511
2512 // Capture an unaliased, unconditional, simple store into an initializer.
2513 // Or, if it is independent of the allocation, hoist it above the allocation.
2514 if (ReduceFieldZeroing && /*can_reshape &&*/
2515 mem->is_Proj() && mem->in(0)->is_Initialize()) {
2516 InitializeNode* init = mem->in(0)->as_Initialize();
2517 intptr_t offset = init->can_capture_store(this, phase, can_reshape);
2518 if (offset > 0) {
2519 Node* moved = init->capture_store(this, offset, phase, can_reshape);
2520 // If the InitializeNode captured me, it made a raw copy of me,
2521 // and I need to disappear.
2522 if (moved != NULL) {
2523 // %%% hack to ensure that Ideal returns a new node:
2524 mem = MergeMemNode::make(phase->C, mem);
2525 return mem; // fold me away
2526 }
2527 }
2528 }
2529
2530 return NULL; // No further progress
2531 }
2532
2533 //------------------------------Value-----------------------------------------
2534 const Type *StoreNode::Value( PhaseTransform *phase ) const {
2535 // Either input is TOP ==> the result is TOP
2536 const Type *t1 = phase->type( in(MemNode::Memory) );
2537 if( t1 == Type::TOP ) return Type::TOP;
2538 const Type *t2 = phase->type( in(MemNode::Address) );
2539 if( t2 == Type::TOP ) return Type::TOP;
2540 const Type *t3 = phase->type( in(MemNode::ValueIn) );
2541 if( t3 == Type::TOP ) return Type::TOP;
2542 return Type::MEMORY;
2543 }
2544
2545 //------------------------------Identity---------------------------------------
2546 // Remove redundant stores:
2547 // Store(m, p, Load(m, p)) changes to m.
2548 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
2549 Node *StoreNode::Identity( PhaseTransform *phase ) {
2550 Node* mem = in(MemNode::Memory);
2551 Node* adr = in(MemNode::Address);
2552 Node* val = in(MemNode::ValueIn);
2553
2554 // Load then Store? Then the Store is useless
2555 if (val->is_Load() &&
2556 val->in(MemNode::Address)->eqv_uncast(adr) &&
2557 val->in(MemNode::Memory )->eqv_uncast(mem) &&
2558 val->as_Load()->store_Opcode() == Opcode()) {
2559 return mem;
2560 }
2561
2562 // Two stores in a row of the same value?
2563 if (mem->is_Store() &&
2564 mem->in(MemNode::Address)->eqv_uncast(adr) &&
2565 mem->in(MemNode::ValueIn)->eqv_uncast(val) &&
2566 mem->Opcode() == Opcode()) {
2567 return mem;
2568 }
2569
2570 // Store of zero anywhere into a freshly-allocated object?
2571 // Then the store is useless.
2572 // (It must already have been captured by the InitializeNode.)
2573 if (ReduceFieldZeroing && phase->type(val)->is_zero_type()) {
2574 // a newly allocated object is already all-zeroes everywhere
2575 if (mem->is_Proj() && mem->in(0)->is_Allocate()) {
2576 return mem;
2577 }
2578
2579 // the store may also apply to zero-bits in an earlier object
2580 Node* prev_mem = find_previous_store(phase);
2581 // Steps (a), (b): Walk past independent stores to find an exact match.
2582 if (prev_mem != NULL) {
2583 Node* prev_val = can_see_stored_value(prev_mem, phase);
2584 if (prev_val != NULL && phase->eqv(prev_val, val)) {
2585 // prev_val and val might differ by a cast; it would be good
2586 // to keep the more informative of the two.
2587 return mem;
2588 }
2589 }
2590 }
2591
2592 return this;
2593 }
2594
2595 //------------------------------match_edge-------------------------------------
2596 // Do we Match on this edge index or not? Match only memory & value
2597 uint StoreNode::match_edge(uint idx) const {
2598 return idx == MemNode::Address || idx == MemNode::ValueIn;
2599 }
2600
2601 //------------------------------cmp--------------------------------------------
2602 // Do not common stores up together. They generally have to be split
2603 // back up anyways, so do not bother.
2604 uint StoreNode::cmp( const Node &n ) const {
2605 return (&n == this); // Always fail except on self
2606 }
2607
2608 //------------------------------Ideal_masked_input-----------------------------
2609 // Check for a useless mask before a partial-word store
2610 // (StoreB ... (AndI valIn conIa) )
2611 // If (conIa & mask == mask) this simplifies to
2612 // (StoreB ... (valIn) )
2613 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
2614 Node *val = in(MemNode::ValueIn);
2615 if( val->Opcode() == Op_AndI ) {
2616 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2617 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
2618 set_req(MemNode::ValueIn, val->in(1));
2619 return this;
2620 }
2621 }
2622 return NULL;
2623 }
2624
2625
2626 //------------------------------Ideal_sign_extended_input----------------------
2627 // Check for useless sign-extension before a partial-word store
2628 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) )
2629 // If (conIL == conIR && conIR <= num_bits) this simplifies to
2630 // (StoreB ... (valIn) )
2631 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) {
2632 Node *val = in(MemNode::ValueIn);
2633 if( val->Opcode() == Op_RShiftI ) {
2634 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2635 if( t && t->is_con() && (t->get_con() <= num_bits) ) {
2636 Node *shl = val->in(1);
2637 if( shl->Opcode() == Op_LShiftI ) {
2638 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int();
2639 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) {
2640 set_req(MemNode::ValueIn, shl->in(1));
2641 return this;
2642 }
2643 }
2644 }
2645 }
2646 return NULL;
2647 }
2648
2649 //------------------------------value_never_loaded-----------------------------------
2650 // Determine whether there are any possible loads of the value stored.
2651 // For simplicity, we actually check if there are any loads from the
2652 // address stored to, not just for loads of the value stored by this node.
2653 //
2654 bool StoreNode::value_never_loaded( PhaseTransform *phase) const {
2655 Node *adr = in(Address);
2656 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
2657 if (adr_oop == NULL)
2658 return false;
2659 if (!adr_oop->is_known_instance_field())
2660 return false; // if not a distinct instance, there may be aliases of the address
2661 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
2662 Node *use = adr->fast_out(i);
2663 int opc = use->Opcode();
2664 if (use->is_Load() || use->is_LoadStore()) {
2665 return false;
2666 }
2667 }
2668 return true;
2669 }
2670
2671 //=============================================================================
2672 //------------------------------Ideal------------------------------------------
2673 // If the store is from an AND mask that leaves the low bits untouched, then
2674 // we can skip the AND operation. If the store is from a sign-extension
2675 // (a left shift, then right shift) we can skip both.
2676 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
2677 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
2678 if( progress != NULL ) return progress;
2679
2680 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
2681 if( progress != NULL ) return progress;
2682
2683 // Finally check the default case
2684 return StoreNode::Ideal(phase, can_reshape);
2685 }
2686
2687 //=============================================================================
2688 //------------------------------Ideal------------------------------------------
2689 // If the store is from an AND mask that leaves the low bits untouched, then
2690 // we can skip the AND operation
2691 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
2692 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
2693 if( progress != NULL ) return progress;
2694
2695 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
2696 if( progress != NULL ) return progress;
2697
2698 // Finally check the default case
2699 return StoreNode::Ideal(phase, can_reshape);
2700 }
2701
2702 //=============================================================================
2703 //------------------------------Identity---------------------------------------
2704 Node *StoreCMNode::Identity( PhaseTransform *phase ) {
2705 // No need to card mark when storing a null ptr
2706 Node* my_store = in(MemNode::OopStore);
2707 if (my_store->is_Store()) {
2708 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) );
2709 if( t1 == TypePtr::NULL_PTR ) {
2710 return in(MemNode::Memory);
2711 }
2712 }
2713 return this;
2714 }
2715
2716 //=============================================================================
2717 //------------------------------Ideal---------------------------------------
2718 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){
2719 Node* progress = StoreNode::Ideal(phase, can_reshape);
2720 if (progress != NULL) return progress;
2721
2722 Node* my_store = in(MemNode::OopStore);
2723 if (my_store->is_MergeMem()) {
2724 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx());
2725 set_req(MemNode::OopStore, mem);
2726 return this;
2727 }
2728
2729 return NULL;
2730 }
2731
2732 //------------------------------Value-----------------------------------------
2733 const Type *StoreCMNode::Value( PhaseTransform *phase ) const {
2734 // Either input is TOP ==> the result is TOP
2735 const Type *t = phase->type( in(MemNode::Memory) );
2736 if( t == Type::TOP ) return Type::TOP;
2737 t = phase->type( in(MemNode::Address) );
2738 if( t == Type::TOP ) return Type::TOP;
2739 t = phase->type( in(MemNode::ValueIn) );
2740 if( t == Type::TOP ) return Type::TOP;
2741 // If extra input is TOP ==> the result is TOP
2742 t = phase->type( in(MemNode::OopStore) );
2743 if( t == Type::TOP ) return Type::TOP;
2744
2745 return StoreNode::Value( phase );
2746 }
2747
2748
2749 //=============================================================================
2750 //----------------------------------SCMemProjNode------------------------------
2751 const Type * SCMemProjNode::Value( PhaseTransform *phase ) const
2752 {
2753 return bottom_type();
2754 }
2755
2756 //=============================================================================
2757 //----------------------------------LoadStoreNode------------------------------
2758 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required )
2759 : Node(required),
2760 _type(rt),
2761 _adr_type(at)
2762 {
2763 init_req(MemNode::Control, c );
2764 init_req(MemNode::Memory , mem);
2765 init_req(MemNode::Address, adr);
2766 init_req(MemNode::ValueIn, val);
2767 init_class_id(Class_LoadStore);
2768 }
2769
2770 uint LoadStoreNode::ideal_reg() const {
2771 return _type->ideal_reg();
2772 }
2773
2774 bool LoadStoreNode::result_not_used() const {
2775 for( DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++ ) {
2776 Node *x = fast_out(i);
2777 if (x->Opcode() == Op_SCMemProj) continue;
2778 return false;
2779 }
2780 return true;
2781 }
2782
2783 uint LoadStoreNode::size_of() const { return sizeof(*this); }
2784
2785 //=============================================================================
2786 //----------------------------------LoadStoreConditionalNode--------------------
2787 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, NULL, TypeInt::BOOL, 5) {
2788 init_req(ExpectedIn, ex );
2789 }
2790
2791 //=============================================================================
2792 //-------------------------------adr_type--------------------------------------
2793 // Do we Match on this edge index or not? Do not match memory
2794 const TypePtr* ClearArrayNode::adr_type() const {
2795 Node *adr = in(3);
2796 return MemNode::calculate_adr_type(adr->bottom_type());
2797 }
2798
2799 //------------------------------match_edge-------------------------------------
2800 // Do we Match on this edge index or not? Do not match memory
2801 uint ClearArrayNode::match_edge(uint idx) const {
2802 return idx > 1;
2803 }
2804
2805 //------------------------------Identity---------------------------------------
2806 // Clearing a zero length array does nothing
2807 Node *ClearArrayNode::Identity( PhaseTransform *phase ) {
2808 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
2809 }
2810
2811 //------------------------------Idealize---------------------------------------
2812 // Clearing a short array is faster with stores
2813 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape){
2814 const int unit = BytesPerLong;
2815 const TypeX* t = phase->type(in(2))->isa_intptr_t();
2816 if (!t) return NULL;
2817 if (!t->is_con()) return NULL;
2818 intptr_t raw_count = t->get_con();
2819 intptr_t size = raw_count;
2820 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
2821 // Clearing nothing uses the Identity call.
2822 // Negative clears are possible on dead ClearArrays
2823 // (see jck test stmt114.stmt11402.val).
2824 if (size <= 0 || size % unit != 0) return NULL;
2825 intptr_t count = size / unit;
2826 // Length too long; use fast hardware clear
2827 if (size > Matcher::init_array_short_size) return NULL;
2828 Node *mem = in(1);
2829 if( phase->type(mem)==Type::TOP ) return NULL;
2830 Node *adr = in(3);
2831 const Type* at = phase->type(adr);
2832 if( at==Type::TOP ) return NULL;
2833 const TypePtr* atp = at->isa_ptr();
2834 // adjust atp to be the correct array element address type
2835 if (atp == NULL) atp = TypePtr::BOTTOM;
2836 else atp = atp->add_offset(Type::OffsetBot);
2837 // Get base for derived pointer purposes
2838 if( adr->Opcode() != Op_AddP ) Unimplemented();
2839 Node *base = adr->in(1);
2840
2841 Node *zero = phase->makecon(TypeLong::ZERO);
2842 Node *off = phase->MakeConX(BytesPerLong);
2843 mem = new (phase->C) StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
2844 count--;
2845 while( count-- ) {
2846 mem = phase->transform(mem);
2847 adr = phase->transform(new (phase->C) AddPNode(base,adr,off));
2848 mem = new (phase->C) StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
2849 }
2850 return mem;
2851 }
2852
2853 //----------------------------step_through----------------------------------
2854 // Return allocation input memory edge if it is different instance
2855 // or itself if it is the one we are looking for.
2856 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) {
2857 Node* n = *np;
2858 assert(n->is_ClearArray(), "sanity");
2859 intptr_t offset;
2860 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
2861 // This method is called only before Allocate nodes are expanded during
2862 // macro nodes expansion. Before that ClearArray nodes are only generated
2863 // in LibraryCallKit::generate_arraycopy() which follows allocations.
2864 assert(alloc != NULL, "should have allocation");
2865 if (alloc->_idx == instance_id) {
2866 // Can not bypass initialization of the instance we are looking for.
2867 return false;
2868 }
2869 // Otherwise skip it.
2870 InitializeNode* init = alloc->initialization();
2871 if (init != NULL)
2872 *np = init->in(TypeFunc::Memory);
2873 else
2874 *np = alloc->in(TypeFunc::Memory);
2875 return true;
2876 }
2877
2878 //----------------------------clear_memory-------------------------------------
2879 // Generate code to initialize object storage to zero.
2880 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2881 intptr_t start_offset,
2882 Node* end_offset,
2883 PhaseGVN* phase) {
2884 Compile* C = phase->C;
2885 intptr_t offset = start_offset;
2886
2887 int unit = BytesPerLong;
2888 if ((offset % unit) != 0) {
2889 Node* adr = new (C) AddPNode(dest, dest, phase->MakeConX(offset));
2890 adr = phase->transform(adr);
2891 const TypePtr* atp = TypeRawPtr::BOTTOM;
2892 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
2893 mem = phase->transform(mem);
2894 offset += BytesPerInt;
2895 }
2896 assert((offset % unit) == 0, "");
2897
2898 // Initialize the remaining stuff, if any, with a ClearArray.
2899 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase);
2900 }
2901
2902 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2903 Node* start_offset,
2904 Node* end_offset,
2905 PhaseGVN* phase) {
2906 if (start_offset == end_offset) {
2907 // nothing to do
2908 return mem;
2909 }
2910
2911 Compile* C = phase->C;
2912 int unit = BytesPerLong;
2913 Node* zbase = start_offset;
2914 Node* zend = end_offset;
2915
2916 // Scale to the unit required by the CPU:
2917 if (!Matcher::init_array_count_is_in_bytes) {
2918 Node* shift = phase->intcon(exact_log2(unit));
2919 zbase = phase->transform( new(C) URShiftXNode(zbase, shift) );
2920 zend = phase->transform( new(C) URShiftXNode(zend, shift) );
2921 }
2922
2923 // Bulk clear double-words
2924 Node* zsize = phase->transform( new(C) SubXNode(zend, zbase) );
2925 Node* adr = phase->transform( new(C) AddPNode(dest, dest, start_offset) );
2926 mem = new (C) ClearArrayNode(ctl, mem, zsize, adr);
2927 return phase->transform(mem);
2928 }
2929
2930 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2931 intptr_t start_offset,
2932 intptr_t end_offset,
2933 PhaseGVN* phase) {
2934 if (start_offset == end_offset) {
2935 // nothing to do
2936 return mem;
2937 }
2938
2939 Compile* C = phase->C;
2940 assert((end_offset % BytesPerInt) == 0, "odd end offset");
2941 intptr_t done_offset = end_offset;
2942 if ((done_offset % BytesPerLong) != 0) {
2943 done_offset -= BytesPerInt;
2944 }
2945 if (done_offset > start_offset) {
2946 mem = clear_memory(ctl, mem, dest,
2947 start_offset, phase->MakeConX(done_offset), phase);
2948 }
2949 if (done_offset < end_offset) { // emit the final 32-bit store
2950 Node* adr = new (C) AddPNode(dest, dest, phase->MakeConX(done_offset));
2951 adr = phase->transform(adr);
2952 const TypePtr* atp = TypeRawPtr::BOTTOM;
2953 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
2954 mem = phase->transform(mem);
2955 done_offset += BytesPerInt;
2956 }
2957 assert(done_offset == end_offset, "");
2958 return mem;
2959 }
2960
2961 //=============================================================================
2962 // Do not match memory edge.
2963 uint StrIntrinsicNode::match_edge(uint idx) const {
2964 return idx == 2 || idx == 3;
2965 }
2966
2967 //------------------------------Ideal------------------------------------------
2968 // Return a node which is more "ideal" than the current node. Strip out
2969 // control copies
2970 Node *StrIntrinsicNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2971 if (remove_dead_region(phase, can_reshape)) return this;
2972 // Don't bother trying to transform a dead node
2973 if (in(0) && in(0)->is_top()) return NULL;
2974
2975 if (can_reshape) {
2976 Node* mem = phase->transform(in(MemNode::Memory));
2977 // If transformed to a MergeMem, get the desired slice
2978 uint alias_idx = phase->C->get_alias_index(adr_type());
2979 mem = mem->is_MergeMem() ? mem->as_MergeMem()->memory_at(alias_idx) : mem;
2980 if (mem != in(MemNode::Memory)) {
2981 set_req(MemNode::Memory, mem);
2982 return this;
2983 }
2984 }
2985 return NULL;
2986 }
2987
2988 //------------------------------Value------------------------------------------
2989 const Type *StrIntrinsicNode::Value( PhaseTransform *phase ) const {
2990 if (in(0) && phase->type(in(0)) == Type::TOP) return Type::TOP;
2991 return bottom_type();
2992 }
2993
2994 //=============================================================================
2995 //------------------------------match_edge-------------------------------------
2996 // Do not match memory edge
2997 uint EncodeISOArrayNode::match_edge(uint idx) const {
2998 return idx == 2 || idx == 3; // EncodeISOArray src (Binary dst len)
2999 }
3000
3001 //------------------------------Ideal------------------------------------------
3002 // Return a node which is more "ideal" than the current node. Strip out
3003 // control copies
3004 Node *EncodeISOArrayNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3005 return remove_dead_region(phase, can_reshape) ? this : NULL;
3006 }
3007
3008 //------------------------------Value------------------------------------------
3009 const Type *EncodeISOArrayNode::Value(PhaseTransform *phase) const {
3010 if (in(0) && phase->type(in(0)) == Type::TOP) return Type::TOP;
3011 return bottom_type();
3012 }
3013
3014 //=============================================================================
3015 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
3016 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)),
3017 _adr_type(C->get_adr_type(alias_idx))
3018 {
3019 init_class_id(Class_MemBar);
3020 Node* top = C->top();
3021 init_req(TypeFunc::I_O,top);
3022 init_req(TypeFunc::FramePtr,top);
3023 init_req(TypeFunc::ReturnAdr,top);
3024 if (precedent != NULL)
3025 init_req(TypeFunc::Parms, precedent);
3026 }
3027
3028 //------------------------------cmp--------------------------------------------
3029 uint MemBarNode::hash() const { return NO_HASH; }
3030 uint MemBarNode::cmp( const Node &n ) const {
3031 return (&n == this); // Always fail except on self
3032 }
3033
3034 //------------------------------make-------------------------------------------
3035 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
3036 switch (opcode) {
3037 case Op_MemBarAcquire: return new(C) MemBarAcquireNode(C, atp, pn);
3038 case Op_LoadFence: return new(C) LoadFenceNode(C, atp, pn);
3039 case Op_MemBarRelease: return new(C) MemBarReleaseNode(C, atp, pn);
3040 case Op_StoreFence: return new(C) StoreFenceNode(C, atp, pn);
3041 case Op_MemBarAcquireLock: return new(C) MemBarAcquireLockNode(C, atp, pn);
3042 case Op_MemBarReleaseLock: return new(C) MemBarReleaseLockNode(C, atp, pn);
3043 case Op_MemBarVolatile: return new(C) MemBarVolatileNode(C, atp, pn);
3044 case Op_MemBarCPUOrder: return new(C) MemBarCPUOrderNode(C, atp, pn);
3045 case Op_Initialize: return new(C) InitializeNode(C, atp, pn);
3046 case Op_MemBarStoreStore: return new(C) MemBarStoreStoreNode(C, atp, pn);
3047 default: ShouldNotReachHere(); return NULL;
3048 }
3049 }
3050
3051 //------------------------------Ideal------------------------------------------
3052 // Return a node which is more "ideal" than the current node. Strip out
3053 // control copies
3054 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3055 if (remove_dead_region(phase, can_reshape)) return this;
3056 // Don't bother trying to transform a dead node
3057 if (in(0) && in(0)->is_top()) {
3058 return NULL;
3059 }
3060
3061 // Eliminate volatile MemBars for scalar replaced objects.
3062 if (can_reshape && req() == (Precedent+1)) {
3063 bool eliminate = false;
3064 int opc = Opcode();
3065 if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) {
3066 // Volatile field loads and stores.
3067 Node* my_mem = in(MemBarNode::Precedent);
3068 // The MembarAquire may keep an unused LoadNode alive through the Precedent edge
3069 if ((my_mem != NULL) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) {
3070 // if the Precedent is a decodeN and its input (a Load) is used at more than one place,
3071 // replace this Precedent (decodeN) with the Load instead.
3072 if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1)) {
3073 Node* load_node = my_mem->in(1);
3074 set_req(MemBarNode::Precedent, load_node);
3075 phase->is_IterGVN()->_worklist.push(my_mem);
3076 my_mem = load_node;
3077 } else {
3078 assert(my_mem->unique_out() == this, "sanity");
3079 del_req(Precedent);
3080 phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later
3081 my_mem = NULL;
3082 }
3083 }
3084 if (my_mem != NULL && my_mem->is_Mem()) {
3085 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
3086 // Check for scalar replaced object reference.
3087 if( t_oop != NULL && t_oop->is_known_instance_field() &&
3088 t_oop->offset() != Type::OffsetBot &&
3089 t_oop->offset() != Type::OffsetTop) {
3090 eliminate = true;
3091 }
3092 }
3093 } else if (opc == Op_MemBarRelease) {
3094 // Final field stores.
3095 Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent), phase);
3096 if ((alloc != NULL) && alloc->is_Allocate() &&
3097 alloc->as_Allocate()->_is_non_escaping) {
3098 // The allocated object does not escape.
3099 eliminate = true;
3100 }
3101 }
3102 if (eliminate) {
3103 // Replace MemBar projections by its inputs.
3104 PhaseIterGVN* igvn = phase->is_IterGVN();
3105 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
3106 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
3107 // Must return either the original node (now dead) or a new node
3108 // (Do not return a top here, since that would break the uniqueness of top.)
3109 return new (phase->C) ConINode(TypeInt::ZERO);
3110 }
3111 }
3112 return NULL;
3113 }
3114
3115 //------------------------------Value------------------------------------------
3116 const Type *MemBarNode::Value( PhaseTransform *phase ) const {
3117 if( !in(0) ) return Type::TOP;
3118 if( phase->type(in(0)) == Type::TOP )
3119 return Type::TOP;
3120 return TypeTuple::MEMBAR;
3121 }
3122
3123 //------------------------------match------------------------------------------
3124 // Construct projections for memory.
3125 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) {
3126 switch (proj->_con) {
3127 case TypeFunc::Control:
3128 case TypeFunc::Memory:
3129 return new (m->C) MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
3130 }
3131 ShouldNotReachHere();
3132 return NULL;
3133 }
3134
3135 //===========================InitializeNode====================================
3136 // SUMMARY:
3137 // This node acts as a memory barrier on raw memory, after some raw stores.
3138 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
3139 // The Initialize can 'capture' suitably constrained stores as raw inits.
3140 // It can coalesce related raw stores into larger units (called 'tiles').
3141 // It can avoid zeroing new storage for memory units which have raw inits.
3142 // At macro-expansion, it is marked 'complete', and does not optimize further.
3143 //
3144 // EXAMPLE:
3145 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
3146 // ctl = incoming control; mem* = incoming memory
3147 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
3148 // First allocate uninitialized memory and fill in the header:
3149 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
3150 // ctl := alloc.Control; mem* := alloc.Memory*
3151 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
3152 // Then initialize to zero the non-header parts of the raw memory block:
3153 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
3154 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
3155 // After the initialize node executes, the object is ready for service:
3156 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
3157 // Suppose its body is immediately initialized as {1,2}:
3158 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3159 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3160 // mem.SLICE(#short[*]) := store2
3161 //
3162 // DETAILS:
3163 // An InitializeNode collects and isolates object initialization after
3164 // an AllocateNode and before the next possible safepoint. As a
3165 // memory barrier (MemBarNode), it keeps critical stores from drifting
3166 // down past any safepoint or any publication of the allocation.
3167 // Before this barrier, a newly-allocated object may have uninitialized bits.
3168 // After this barrier, it may be treated as a real oop, and GC is allowed.
3169 //
3170 // The semantics of the InitializeNode include an implicit zeroing of
3171 // the new object from object header to the end of the object.
3172 // (The object header and end are determined by the AllocateNode.)
3173 //
3174 // Certain stores may be added as direct inputs to the InitializeNode.
3175 // These stores must update raw memory, and they must be to addresses
3176 // derived from the raw address produced by AllocateNode, and with
3177 // a constant offset. They must be ordered by increasing offset.
3178 // The first one is at in(RawStores), the last at in(req()-1).
3179 // Unlike most memory operations, they are not linked in a chain,
3180 // but are displayed in parallel as users of the rawmem output of
3181 // the allocation.
3182 //
3183 // (See comments in InitializeNode::capture_store, which continue
3184 // the example given above.)
3185 //
3186 // When the associated Allocate is macro-expanded, the InitializeNode
3187 // may be rewritten to optimize collected stores. A ClearArrayNode
3188 // may also be created at that point to represent any required zeroing.
3189 // The InitializeNode is then marked 'complete', prohibiting further
3190 // capturing of nearby memory operations.
3191 //
3192 // During macro-expansion, all captured initializations which store
3193 // constant values of 32 bits or smaller are coalesced (if advantageous)
3194 // into larger 'tiles' 32 or 64 bits. This allows an object to be
3195 // initialized in fewer memory operations. Memory words which are
3196 // covered by neither tiles nor non-constant stores are pre-zeroed
3197 // by explicit stores of zero. (The code shape happens to do all
3198 // zeroing first, then all other stores, with both sequences occurring
3199 // in order of ascending offsets.)
3200 //
3201 // Alternatively, code may be inserted between an AllocateNode and its
3202 // InitializeNode, to perform arbitrary initialization of the new object.
3203 // E.g., the object copying intrinsics insert complex data transfers here.
3204 // The initialization must then be marked as 'complete' disable the
3205 // built-in zeroing semantics and the collection of initializing stores.
3206 //
3207 // While an InitializeNode is incomplete, reads from the memory state
3208 // produced by it are optimizable if they match the control edge and
3209 // new oop address associated with the allocation/initialization.
3210 // They return a stored value (if the offset matches) or else zero.
3211 // A write to the memory state, if it matches control and address,
3212 // and if it is to a constant offset, may be 'captured' by the
3213 // InitializeNode. It is cloned as a raw memory operation and rewired
3214 // inside the initialization, to the raw oop produced by the allocation.
3215 // Operations on addresses which are provably distinct (e.g., to
3216 // other AllocateNodes) are allowed to bypass the initialization.
3217 //
3218 // The effect of all this is to consolidate object initialization
3219 // (both arrays and non-arrays, both piecewise and bulk) into a
3220 // single location, where it can be optimized as a unit.
3221 //
3222 // Only stores with an offset less than TrackedInitializationLimit words
3223 // will be considered for capture by an InitializeNode. This puts a
3224 // reasonable limit on the complexity of optimized initializations.
3225
3226 //---------------------------InitializeNode------------------------------------
3227 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
3228 : _is_complete(Incomplete), _does_not_escape(false),
3229 MemBarNode(C, adr_type, rawoop)
3230 {
3231 init_class_id(Class_Initialize);
3232
3233 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
3234 assert(in(RawAddress) == rawoop, "proper init");
3235 // Note: allocation() can be NULL, for secondary initialization barriers
3236 }
3237
3238 // Since this node is not matched, it will be processed by the
3239 // register allocator. Declare that there are no constraints
3240 // on the allocation of the RawAddress edge.
3241 const RegMask &InitializeNode::in_RegMask(uint idx) const {
3242 // This edge should be set to top, by the set_complete. But be conservative.
3243 if (idx == InitializeNode::RawAddress)
3244 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
3245 return RegMask::Empty;
3246 }
3247
3248 Node* InitializeNode::memory(uint alias_idx) {
3249 Node* mem = in(Memory);
3250 if (mem->is_MergeMem()) {
3251 return mem->as_MergeMem()->memory_at(alias_idx);
3252 } else {
3253 // incoming raw memory is not split
3254 return mem;
3255 }
3256 }
3257
3258 bool InitializeNode::is_non_zero() {
3259 if (is_complete()) return false;
3260 remove_extra_zeroes();
3261 return (req() > RawStores);
3262 }
3263
3264 void InitializeNode::set_complete(PhaseGVN* phase) {
3265 assert(!is_complete(), "caller responsibility");
3266 _is_complete = Complete;
3267
3268 // After this node is complete, it contains a bunch of
3269 // raw-memory initializations. There is no need for
3270 // it to have anything to do with non-raw memory effects.
3271 // Therefore, tell all non-raw users to re-optimize themselves,
3272 // after skipping the memory effects of this initialization.
3273 PhaseIterGVN* igvn = phase->is_IterGVN();
3274 if (igvn) igvn->add_users_to_worklist(this);
3275 }
3276
3277 // convenience function
3278 // return false if the init contains any stores already
3279 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
3280 InitializeNode* init = initialization();
3281 if (init == NULL || init->is_complete()) return false;
3282 init->remove_extra_zeroes();
3283 // for now, if this allocation has already collected any inits, bail:
3284 if (init->is_non_zero()) return false;
3285 init->set_complete(phase);
3286 return true;
3287 }
3288
3289 void InitializeNode::remove_extra_zeroes() {
3290 if (req() == RawStores) return;
3291 Node* zmem = zero_memory();
3292 uint fill = RawStores;
3293 for (uint i = fill; i < req(); i++) {
3294 Node* n = in(i);
3295 if (n->is_top() || n == zmem) continue; // skip
3296 if (fill < i) set_req(fill, n); // compact
3297 ++fill;
3298 }
3299 // delete any empty spaces created:
3300 while (fill < req()) {
3301 del_req(fill);
3302 }
3303 }
3304
3305 // Helper for remembering which stores go with which offsets.
3306 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) {
3307 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
3308 intptr_t offset = -1;
3309 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
3310 phase, offset);
3311 if (base == NULL) return -1; // something is dead,
3312 if (offset < 0) return -1; // dead, dead
3313 return offset;
3314 }
3315
3316 // Helper for proving that an initialization expression is
3317 // "simple enough" to be folded into an object initialization.
3318 // Attempts to prove that a store's initial value 'n' can be captured
3319 // within the initialization without creating a vicious cycle, such as:
3320 // { Foo p = new Foo(); p.next = p; }
3321 // True for constants and parameters and small combinations thereof.
3322 bool InitializeNode::detect_init_independence(Node* n, int& count) {
3323 if (n == NULL) return true; // (can this really happen?)
3324 if (n->is_Proj()) n = n->in(0);
3325 if (n == this) return false; // found a cycle
3326 if (n->is_Con()) return true;
3327 if (n->is_Start()) return true; // params, etc., are OK
3328 if (n->is_Root()) return true; // even better
3329
3330 Node* ctl = n->in(0);
3331 if (ctl != NULL && !ctl->is_top()) {
3332 if (ctl->is_Proj()) ctl = ctl->in(0);
3333 if (ctl == this) return false;
3334
3335 // If we already know that the enclosing memory op is pinned right after
3336 // the init, then any control flow that the store has picked up
3337 // must have preceded the init, or else be equal to the init.
3338 // Even after loop optimizations (which might change control edges)
3339 // a store is never pinned *before* the availability of its inputs.
3340 if (!MemNode::all_controls_dominate(n, this))
3341 return false; // failed to prove a good control
3342 }
3343
3344 // Check data edges for possible dependencies on 'this'.
3345 if ((count += 1) > 20) return false; // complexity limit
3346 for (uint i = 1; i < n->req(); i++) {
3347 Node* m = n->in(i);
3348 if (m == NULL || m == n || m->is_top()) continue;
3349 uint first_i = n->find_edge(m);
3350 if (i != first_i) continue; // process duplicate edge just once
3351 if (!detect_init_independence(m, count)) {
3352 return false;
3353 }
3354 }
3355
3356 return true;
3357 }
3358
3359 // Here are all the checks a Store must pass before it can be moved into
3360 // an initialization. Returns zero if a check fails.
3361 // On success, returns the (constant) offset to which the store applies,
3362 // within the initialized memory.
3363 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase, bool can_reshape) {
3364 const int FAIL = 0;
3365 if (st->req() != MemNode::ValueIn + 1)
3366 return FAIL; // an inscrutable StoreNode (card mark?)
3367 Node* ctl = st->in(MemNode::Control);
3368 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this))
3369 return FAIL; // must be unconditional after the initialization
3370 Node* mem = st->in(MemNode::Memory);
3371 if (!(mem->is_Proj() && mem->in(0) == this))
3372 return FAIL; // must not be preceded by other stores
3373 Node* adr = st->in(MemNode::Address);
3374 intptr_t offset;
3375 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
3376 if (alloc == NULL)
3377 return FAIL; // inscrutable address
3378 if (alloc != allocation())
3379 return FAIL; // wrong allocation! (store needs to float up)
3380 int size_in_bytes = st->memory_size();
3381 if ((size_in_bytes != 0) && (offset % size_in_bytes) != 0) {
3382 return FAIL; // mismatched access
3383 }
3384 Node* val = st->in(MemNode::ValueIn);
3385 int complexity_count = 0;
3386 if (!detect_init_independence(val, complexity_count))
3387 return FAIL; // stored value must be 'simple enough'
3388
3389 // The Store can be captured only if nothing after the allocation
3390 // and before the Store is using the memory location that the store
3391 // overwrites.
3392 bool failed = false;
3393 // If is_complete_with_arraycopy() is true the shape of the graph is
3394 // well defined and is safe so no need for extra checks.
3395 if (!is_complete_with_arraycopy()) {
3396 // We are going to look at each use of the memory state following
3397 // the allocation to make sure nothing reads the memory that the
3398 // Store writes.
3399 const TypePtr* t_adr = phase->type(adr)->isa_ptr();
3400 int alias_idx = phase->C->get_alias_index(t_adr);
3401 ResourceMark rm;
3402 Unique_Node_List mems;
3403 mems.push(mem);
3404 Node* unique_merge = NULL;
3405 for (uint next = 0; next < mems.size(); ++next) {
3406 Node *m = mems.at(next);
3407 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
3408 Node *n = m->fast_out(j);
3409 if (n->outcnt() == 0) {
3410 continue;
3411 }
3412 if (n == st) {
3413 continue;
3414 } else if (n->in(0) != NULL && n->in(0) != ctl) {
3415 // If the control of this use is different from the control
3416 // of the Store which is right after the InitializeNode then
3417 // this node cannot be between the InitializeNode and the
3418 // Store.
3419 continue;
3420 } else if (n->is_MergeMem()) {
3421 if (n->as_MergeMem()->memory_at(alias_idx) == m) {
3422 // We can hit a MergeMemNode (that will likely go away
3423 // later) that is a direct use of the memory state
3424 // following the InitializeNode on the same slice as the
3425 // store node that we'd like to capture. We need to check
3426 // the uses of the MergeMemNode.
3427 mems.push(n);
3428 }
3429 } else if (n->is_Mem()) {
3430 Node* other_adr = n->in(MemNode::Address);
3431 if (other_adr == adr) {
3432 failed = true;
3433 break;
3434 } else {
3435 const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr();
3436 if (other_t_adr != NULL) {
3437 int other_alias_idx = phase->C->get_alias_index(other_t_adr);
3438 if (other_alias_idx == alias_idx) {
3439 // A load from the same memory slice as the store right
3440 // after the InitializeNode. We check the control of the
3441 // object/array that is loaded from. If it's the same as
3442 // the store control then we cannot capture the store.
3443 assert(!n->is_Store(), "2 stores to same slice on same control?");
3444 Node* base = other_adr;
3445 assert(base->is_AddP(), err_msg_res("should be addp but is %s", base->Name()));
3446 base = base->in(AddPNode::Base);
3447 if (base != NULL) {
3448 base = base->uncast();
3449 if (base->is_Proj() && base->in(0) == alloc) {
3450 failed = true;
3451 break;
3452 }
3453 }
3454 }
3455 }
3456 }
3457 } else {
3458 failed = true;
3459 break;
3460 }
3461 }
3462 }
3463 }
3464 if (failed) {
3465 if (!can_reshape) {
3466 // We decided we couldn't capture the store during parsing. We
3467 // should try again during the next IGVN once the graph is
3468 // cleaner.
3469 phase->C->record_for_igvn(st);
3470 }
3471 return FAIL;
3472 }
3473
3474 return offset; // success
3475 }
3476
3477 // Find the captured store in(i) which corresponds to the range
3478 // [start..start+size) in the initialized object.
3479 // If there is one, return its index i. If there isn't, return the
3480 // negative of the index where it should be inserted.
3481 // Return 0 if the queried range overlaps an initialization boundary
3482 // or if dead code is encountered.
3483 // If size_in_bytes is zero, do not bother with overlap checks.
3484 int InitializeNode::captured_store_insertion_point(intptr_t start,
3485 int size_in_bytes,
3486 PhaseTransform* phase) {
3487 const int FAIL = 0, MAX_STORE = BytesPerLong;
3488
3489 if (is_complete())
3490 return FAIL; // arraycopy got here first; punt
3491
3492 assert(allocation() != NULL, "must be present");
3493
3494 // no negatives, no header fields:
3495 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
3496
3497 // after a certain size, we bail out on tracking all the stores:
3498 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3499 if (start >= ti_limit) return FAIL;
3500
3501 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
3502 if (i >= limit) return -(int)i; // not found; here is where to put it
3503
3504 Node* st = in(i);
3505 intptr_t st_off = get_store_offset(st, phase);
3506 if (st_off < 0) {
3507 if (st != zero_memory()) {
3508 return FAIL; // bail out if there is dead garbage
3509 }
3510 } else if (st_off > start) {
3511 // ...we are done, since stores are ordered
3512 if (st_off < start + size_in_bytes) {
3513 return FAIL; // the next store overlaps
3514 }
3515 return -(int)i; // not found; here is where to put it
3516 } else if (st_off < start) {
3517 if (size_in_bytes != 0 &&
3518 start < st_off + MAX_STORE &&
3519 start < st_off + st->as_Store()->memory_size()) {
3520 return FAIL; // the previous store overlaps
3521 }
3522 } else {
3523 if (size_in_bytes != 0 &&
3524 st->as_Store()->memory_size() != size_in_bytes) {
3525 return FAIL; // mismatched store size
3526 }
3527 return i;
3528 }
3529
3530 ++i;
3531 }
3532 }
3533
3534 // Look for a captured store which initializes at the offset 'start'
3535 // with the given size. If there is no such store, and no other
3536 // initialization interferes, then return zero_memory (the memory
3537 // projection of the AllocateNode).
3538 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
3539 PhaseTransform* phase) {
3540 assert(stores_are_sane(phase), "");
3541 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3542 if (i == 0) {
3543 return NULL; // something is dead
3544 } else if (i < 0) {
3545 return zero_memory(); // just primordial zero bits here
3546 } else {
3547 Node* st = in(i); // here is the store at this position
3548 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
3549 return st;
3550 }
3551 }
3552
3553 // Create, as a raw pointer, an address within my new object at 'offset'.
3554 Node* InitializeNode::make_raw_address(intptr_t offset,
3555 PhaseTransform* phase) {
3556 Node* addr = in(RawAddress);
3557 if (offset != 0) {
3558 Compile* C = phase->C;
3559 addr = phase->transform( new (C) AddPNode(C->top(), addr,
3560 phase->MakeConX(offset)) );
3561 }
3562 return addr;
3563 }
3564
3565 // Clone the given store, converting it into a raw store
3566 // initializing a field or element of my new object.
3567 // Caller is responsible for retiring the original store,
3568 // with subsume_node or the like.
3569 //
3570 // From the example above InitializeNode::InitializeNode,
3571 // here are the old stores to be captured:
3572 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3573 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3574 //
3575 // Here is the changed code; note the extra edges on init:
3576 // alloc = (Allocate ...)
3577 // rawoop = alloc.RawAddress
3578 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
3579 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
3580 // init = (Initialize alloc.Control alloc.Memory rawoop
3581 // rawstore1 rawstore2)
3582 //
3583 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
3584 PhaseTransform* phase, bool can_reshape) {
3585 assert(stores_are_sane(phase), "");
3586
3587 if (start < 0) return NULL;
3588 assert(can_capture_store(st, phase, can_reshape) == start, "sanity");
3589
3590 Compile* C = phase->C;
3591 int size_in_bytes = st->memory_size();
3592 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3593 if (i == 0) return NULL; // bail out
3594 Node* prev_mem = NULL; // raw memory for the captured store
3595 if (i > 0) {
3596 prev_mem = in(i); // there is a pre-existing store under this one
3597 set_req(i, C->top()); // temporarily disconnect it
3598 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
3599 } else {
3600 i = -i; // no pre-existing store
3601 prev_mem = zero_memory(); // a slice of the newly allocated object
3602 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
3603 set_req(--i, C->top()); // reuse this edge; it has been folded away
3604 else
3605 ins_req(i, C->top()); // build a new edge
3606 }
3607 Node* new_st = st->clone();
3608 new_st->set_req(MemNode::Control, in(Control));
3609 new_st->set_req(MemNode::Memory, prev_mem);
3610 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
3611 new_st = phase->transform(new_st);
3612
3613 // At this point, new_st might have swallowed a pre-existing store
3614 // at the same offset, or perhaps new_st might have disappeared,
3615 // if it redundantly stored the same value (or zero to fresh memory).
3616
3617 // In any case, wire it in:
3618 set_req(i, new_st);
3619
3620 // The caller may now kill the old guy.
3621 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
3622 assert(check_st == new_st || check_st == NULL, "must be findable");
3623 assert(!is_complete(), "");
3624 return new_st;
3625 }
3626
3627 static bool store_constant(jlong* tiles, int num_tiles,
3628 intptr_t st_off, int st_size,
3629 jlong con) {
3630 if ((st_off & (st_size-1)) != 0)
3631 return false; // strange store offset (assume size==2**N)
3632 address addr = (address)tiles + st_off;
3633 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
3634 switch (st_size) {
3635 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
3636 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
3637 case sizeof(jint): *(jint*) addr = (jint) con; break;
3638 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
3639 default: return false; // strange store size (detect size!=2**N here)
3640 }
3641 return true; // return success to caller
3642 }
3643
3644 // Coalesce subword constants into int constants and possibly
3645 // into long constants. The goal, if the CPU permits,
3646 // is to initialize the object with a small number of 64-bit tiles.
3647 // Also, convert floating-point constants to bit patterns.
3648 // Non-constants are not relevant to this pass.
3649 //
3650 // In terms of the running example on InitializeNode::InitializeNode
3651 // and InitializeNode::capture_store, here is the transformation
3652 // of rawstore1 and rawstore2 into rawstore12:
3653 // alloc = (Allocate ...)
3654 // rawoop = alloc.RawAddress
3655 // tile12 = 0x00010002
3656 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
3657 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
3658 //
3659 void
3660 InitializeNode::coalesce_subword_stores(intptr_t header_size,
3661 Node* size_in_bytes,
3662 PhaseGVN* phase) {
3663 Compile* C = phase->C;
3664
3665 assert(stores_are_sane(phase), "");
3666 // Note: After this pass, they are not completely sane,
3667 // since there may be some overlaps.
3668
3669 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
3670
3671 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3672 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
3673 size_limit = MIN2(size_limit, ti_limit);
3674 size_limit = align_size_up(size_limit, BytesPerLong);
3675 int num_tiles = size_limit / BytesPerLong;
3676
3677 // allocate space for the tile map:
3678 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
3679 jlong tiles_buf[small_len];
3680 Node* nodes_buf[small_len];
3681 jlong inits_buf[small_len];
3682 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
3683 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3684 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
3685 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
3686 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
3687 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3688 // tiles: exact bitwise model of all primitive constants
3689 // nodes: last constant-storing node subsumed into the tiles model
3690 // inits: which bytes (in each tile) are touched by any initializations
3691
3692 //// Pass A: Fill in the tile model with any relevant stores.
3693
3694 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
3695 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
3696 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
3697 Node* zmem = zero_memory(); // initially zero memory state
3698 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3699 Node* st = in(i);
3700 intptr_t st_off = get_store_offset(st, phase);
3701
3702 // Figure out the store's offset and constant value:
3703 if (st_off < header_size) continue; //skip (ignore header)
3704 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
3705 int st_size = st->as_Store()->memory_size();
3706 if (st_off + st_size > size_limit) break;
3707
3708 // Record which bytes are touched, whether by constant or not.
3709 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
3710 continue; // skip (strange store size)
3711
3712 const Type* val = phase->type(st->in(MemNode::ValueIn));
3713 if (!val->singleton()) continue; //skip (non-con store)
3714 BasicType type = val->basic_type();
3715
3716 jlong con = 0;
3717 switch (type) {
3718 case T_INT: con = val->is_int()->get_con(); break;
3719 case T_LONG: con = val->is_long()->get_con(); break;
3720 case T_FLOAT: con = jint_cast(val->getf()); break;
3721 case T_DOUBLE: con = jlong_cast(val->getd()); break;
3722 default: continue; //skip (odd store type)
3723 }
3724
3725 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
3726 st->Opcode() == Op_StoreL) {
3727 continue; // This StoreL is already optimal.
3728 }
3729
3730 // Store down the constant.
3731 store_constant(tiles, num_tiles, st_off, st_size, con);
3732
3733 intptr_t j = st_off >> LogBytesPerLong;
3734
3735 if (type == T_INT && st_size == BytesPerInt
3736 && (st_off & BytesPerInt) == BytesPerInt) {
3737 jlong lcon = tiles[j];
3738 if (!Matcher::isSimpleConstant64(lcon) &&
3739 st->Opcode() == Op_StoreI) {
3740 // This StoreI is already optimal by itself.
3741 jint* intcon = (jint*) &tiles[j];
3742 intcon[1] = 0; // undo the store_constant()
3743
3744 // If the previous store is also optimal by itself, back up and
3745 // undo the action of the previous loop iteration... if we can.
3746 // But if we can't, just let the previous half take care of itself.
3747 st = nodes[j];
3748 st_off -= BytesPerInt;
3749 con = intcon[0];
3750 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) {
3751 assert(st_off >= header_size, "still ignoring header");
3752 assert(get_store_offset(st, phase) == st_off, "must be");
3753 assert(in(i-1) == zmem, "must be");
3754 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
3755 assert(con == tcon->is_int()->get_con(), "must be");
3756 // Undo the effects of the previous loop trip, which swallowed st:
3757 intcon[0] = 0; // undo store_constant()
3758 set_req(i-1, st); // undo set_req(i, zmem)
3759 nodes[j] = NULL; // undo nodes[j] = st
3760 --old_subword; // undo ++old_subword
3761 }
3762 continue; // This StoreI is already optimal.
3763 }
3764 }
3765
3766 // This store is not needed.
3767 set_req(i, zmem);
3768 nodes[j] = st; // record for the moment
3769 if (st_size < BytesPerLong) // something has changed
3770 ++old_subword; // includes int/float, but who's counting...
3771 else ++old_long;
3772 }
3773
3774 if ((old_subword + old_long) == 0)
3775 return; // nothing more to do
3776
3777 //// Pass B: Convert any non-zero tiles into optimal constant stores.
3778 // Be sure to insert them before overlapping non-constant stores.
3779 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
3780 for (int j = 0; j < num_tiles; j++) {
3781 jlong con = tiles[j];
3782 jlong init = inits[j];
3783 if (con == 0) continue;
3784 jint con0, con1; // split the constant, address-wise
3785 jint init0, init1; // split the init map, address-wise
3786 { union { jlong con; jint intcon[2]; } u;
3787 u.con = con;
3788 con0 = u.intcon[0];
3789 con1 = u.intcon[1];
3790 u.con = init;
3791 init0 = u.intcon[0];
3792 init1 = u.intcon[1];
3793 }
3794
3795 Node* old = nodes[j];
3796 assert(old != NULL, "need the prior store");
3797 intptr_t offset = (j * BytesPerLong);
3798
3799 bool split = !Matcher::isSimpleConstant64(con);
3800
3801 if (offset < header_size) {
3802 assert(offset + BytesPerInt >= header_size, "second int counts");
3803 assert(*(jint*)&tiles[j] == 0, "junk in header");
3804 split = true; // only the second word counts
3805 // Example: int a[] = { 42 ... }
3806 } else if (con0 == 0 && init0 == -1) {
3807 split = true; // first word is covered by full inits
3808 // Example: int a[] = { ... foo(), 42 ... }
3809 } else if (con1 == 0 && init1 == -1) {
3810 split = true; // second word is covered by full inits
3811 // Example: int a[] = { ... 42, foo() ... }
3812 }
3813
3814 // Here's a case where init0 is neither 0 nor -1:
3815 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
3816 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
3817 // In this case the tile is not split; it is (jlong)42.
3818 // The big tile is stored down, and then the foo() value is inserted.
3819 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
3820
3821 Node* ctl = old->in(MemNode::Control);
3822 Node* adr = make_raw_address(offset, phase);
3823 const TypePtr* atp = TypeRawPtr::BOTTOM;
3824
3825 // One or two coalesced stores to plop down.
3826 Node* st[2];
3827 intptr_t off[2];
3828 int nst = 0;
3829 if (!split) {
3830 ++new_long;
3831 off[nst] = offset;
3832 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3833 phase->longcon(con), T_LONG, MemNode::unordered);
3834 } else {
3835 // Omit either if it is a zero.
3836 if (con0 != 0) {
3837 ++new_int;
3838 off[nst] = offset;
3839 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3840 phase->intcon(con0), T_INT, MemNode::unordered);
3841 }
3842 if (con1 != 0) {
3843 ++new_int;
3844 offset += BytesPerInt;
3845 adr = make_raw_address(offset, phase);
3846 off[nst] = offset;
3847 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3848 phase->intcon(con1), T_INT, MemNode::unordered);
3849 }
3850 }
3851
3852 // Insert second store first, then the first before the second.
3853 // Insert each one just before any overlapping non-constant stores.
3854 while (nst > 0) {
3855 Node* st1 = st[--nst];
3856 C->copy_node_notes_to(st1, old);
3857 st1 = phase->transform(st1);
3858 offset = off[nst];
3859 assert(offset >= header_size, "do not smash header");
3860 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
3861 guarantee(ins_idx != 0, "must re-insert constant store");
3862 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
3863 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
3864 set_req(--ins_idx, st1);
3865 else
3866 ins_req(ins_idx, st1);
3867 }
3868 }
3869
3870 if (PrintCompilation && WizardMode)
3871 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
3872 old_subword, old_long, new_int, new_long);
3873 if (C->log() != NULL)
3874 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
3875 old_subword, old_long, new_int, new_long);
3876
3877 // Clean up any remaining occurrences of zmem:
3878 remove_extra_zeroes();
3879 }
3880
3881 // Explore forward from in(start) to find the first fully initialized
3882 // word, and return its offset. Skip groups of subword stores which
3883 // together initialize full words. If in(start) is itself part of a
3884 // fully initialized word, return the offset of in(start). If there
3885 // are no following full-word stores, or if something is fishy, return
3886 // a negative value.
3887 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
3888 int int_map = 0;
3889 intptr_t int_map_off = 0;
3890 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
3891
3892 for (uint i = start, limit = req(); i < limit; i++) {
3893 Node* st = in(i);
3894
3895 intptr_t st_off = get_store_offset(st, phase);
3896 if (st_off < 0) break; // return conservative answer
3897
3898 int st_size = st->as_Store()->memory_size();
3899 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
3900 return st_off; // we found a complete word init
3901 }
3902
3903 // update the map:
3904
3905 intptr_t this_int_off = align_size_down(st_off, BytesPerInt);
3906 if (this_int_off != int_map_off) {
3907 // reset the map:
3908 int_map = 0;
3909 int_map_off = this_int_off;
3910 }
3911
3912 int subword_off = st_off - this_int_off;
3913 int_map |= right_n_bits(st_size) << subword_off;
3914 if ((int_map & FULL_MAP) == FULL_MAP) {
3915 return this_int_off; // we found a complete word init
3916 }
3917
3918 // Did this store hit or cross the word boundary?
3919 intptr_t next_int_off = align_size_down(st_off + st_size, BytesPerInt);
3920 if (next_int_off == this_int_off + BytesPerInt) {
3921 // We passed the current int, without fully initializing it.
3922 int_map_off = next_int_off;
3923 int_map >>= BytesPerInt;
3924 } else if (next_int_off > this_int_off + BytesPerInt) {
3925 // We passed the current and next int.
3926 return this_int_off + BytesPerInt;
3927 }
3928 }
3929
3930 return -1;
3931 }
3932
3933
3934 // Called when the associated AllocateNode is expanded into CFG.
3935 // At this point, we may perform additional optimizations.
3936 // Linearize the stores by ascending offset, to make memory
3937 // activity as coherent as possible.
3938 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
3939 intptr_t header_size,
3940 Node* size_in_bytes,
3941 PhaseGVN* phase) {
3942 assert(!is_complete(), "not already complete");
3943 assert(stores_are_sane(phase), "");
3944 assert(allocation() != NULL, "must be present");
3945
3946 remove_extra_zeroes();
3947
3948 if (ReduceFieldZeroing || ReduceBulkZeroing)
3949 // reduce instruction count for common initialization patterns
3950 coalesce_subword_stores(header_size, size_in_bytes, phase);
3951
3952 Node* zmem = zero_memory(); // initially zero memory state
3953 Node* inits = zmem; // accumulating a linearized chain of inits
3954 #ifdef ASSERT
3955 intptr_t first_offset = allocation()->minimum_header_size();
3956 intptr_t last_init_off = first_offset; // previous init offset
3957 intptr_t last_init_end = first_offset; // previous init offset+size
3958 intptr_t last_tile_end = first_offset; // previous tile offset+size
3959 #endif
3960 intptr_t zeroes_done = header_size;
3961
3962 bool do_zeroing = true; // we might give up if inits are very sparse
3963 int big_init_gaps = 0; // how many large gaps have we seen?
3964
3965 if (ZeroTLAB) do_zeroing = false;
3966 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
3967
3968 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3969 Node* st = in(i);
3970 intptr_t st_off = get_store_offset(st, phase);
3971 if (st_off < 0)
3972 break; // unknown junk in the inits
3973 if (st->in(MemNode::Memory) != zmem)
3974 break; // complicated store chains somehow in list
3975
3976 int st_size = st->as_Store()->memory_size();
3977 intptr_t next_init_off = st_off + st_size;
3978
3979 if (do_zeroing && zeroes_done < next_init_off) {
3980 // See if this store needs a zero before it or under it.
3981 intptr_t zeroes_needed = st_off;
3982
3983 if (st_size < BytesPerInt) {
3984 // Look for subword stores which only partially initialize words.
3985 // If we find some, we must lay down some word-level zeroes first,
3986 // underneath the subword stores.
3987 //
3988 // Examples:
3989 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
3990 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
3991 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
3992 //
3993 // Note: coalesce_subword_stores may have already done this,
3994 // if it was prompted by constant non-zero subword initializers.
3995 // But this case can still arise with non-constant stores.
3996
3997 intptr_t next_full_store = find_next_fullword_store(i, phase);
3998
3999 // In the examples above:
4000 // in(i) p q r s x y z
4001 // st_off 12 13 14 15 12 13 14
4002 // st_size 1 1 1 1 1 1 1
4003 // next_full_s. 12 16 16 16 16 16 16
4004 // z's_done 12 16 16 16 12 16 12
4005 // z's_needed 12 16 16 16 16 16 16
4006 // zsize 0 0 0 0 4 0 4
4007 if (next_full_store < 0) {
4008 // Conservative tack: Zero to end of current word.
4009 zeroes_needed = align_size_up(zeroes_needed, BytesPerInt);
4010 } else {
4011 // Zero to beginning of next fully initialized word.
4012 // Or, don't zero at all, if we are already in that word.
4013 assert(next_full_store >= zeroes_needed, "must go forward");
4014 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
4015 zeroes_needed = next_full_store;
4016 }
4017 }
4018
4019 if (zeroes_needed > zeroes_done) {
4020 intptr_t zsize = zeroes_needed - zeroes_done;
4021 // Do some incremental zeroing on rawmem, in parallel with inits.
4022 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
4023 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
4024 zeroes_done, zeroes_needed,
4025 phase);
4026 zeroes_done = zeroes_needed;
4027 if (zsize > Matcher::init_array_short_size && ++big_init_gaps > 2)
4028 do_zeroing = false; // leave the hole, next time
4029 }
4030 }
4031
4032 // Collect the store and move on:
4033 st->set_req(MemNode::Memory, inits);
4034 inits = st; // put it on the linearized chain
4035 set_req(i, zmem); // unhook from previous position
4036
4037 if (zeroes_done == st_off)
4038 zeroes_done = next_init_off;
4039
4040 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
4041
4042 #ifdef ASSERT
4043 // Various order invariants. Weaker than stores_are_sane because
4044 // a large constant tile can be filled in by smaller non-constant stores.
4045 assert(st_off >= last_init_off, "inits do not reverse");
4046 last_init_off = st_off;
4047 const Type* val = NULL;
4048 if (st_size >= BytesPerInt &&
4049 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
4050 (int)val->basic_type() < (int)T_OBJECT) {
4051 assert(st_off >= last_tile_end, "tiles do not overlap");
4052 assert(st_off >= last_init_end, "tiles do not overwrite inits");
4053 last_tile_end = MAX2(last_tile_end, next_init_off);
4054 } else {
4055 intptr_t st_tile_end = align_size_up(next_init_off, BytesPerLong);
4056 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
4057 assert(st_off >= last_init_end, "inits do not overlap");
4058 last_init_end = next_init_off; // it's a non-tile
4059 }
4060 #endif //ASSERT
4061 }
4062
4063 remove_extra_zeroes(); // clear out all the zmems left over
4064 add_req(inits);
4065
4066 if (!ZeroTLAB) {
4067 // If anything remains to be zeroed, zero it all now.
4068 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
4069 // if it is the last unused 4 bytes of an instance, forget about it
4070 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
4071 if (zeroes_done + BytesPerLong >= size_limit) {
4072 AllocateNode* alloc = allocation();
4073 assert(alloc != NULL, "must be present");
4074 if (alloc != NULL && alloc->Opcode() == Op_Allocate) {
4075 Node* klass_node = alloc->in(AllocateNode::KlassNode);
4076 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass();
4077 if (zeroes_done == k->layout_helper())
4078 zeroes_done = size_limit;
4079 }
4080 }
4081 if (zeroes_done < size_limit) {
4082 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
4083 zeroes_done, size_in_bytes, phase);
4084 }
4085 }
4086
4087 set_complete(phase);
4088 return rawmem;
4089 }
4090
4091
4092 #ifdef ASSERT
4093 bool InitializeNode::stores_are_sane(PhaseTransform* phase) {
4094 if (is_complete())
4095 return true; // stores could be anything at this point
4096 assert(allocation() != NULL, "must be present");
4097 intptr_t last_off = allocation()->minimum_header_size();
4098 for (uint i = InitializeNode::RawStores; i < req(); i++) {
4099 Node* st = in(i);
4100 intptr_t st_off = get_store_offset(st, phase);
4101 if (st_off < 0) continue; // ignore dead garbage
4102 if (last_off > st_off) {
4103 tty->print_cr("*** bad store offset at %d: " INTX_FORMAT " > " INTX_FORMAT, i, last_off, st_off);
4104 this->dump(2);
4105 assert(false, "ascending store offsets");
4106 return false;
4107 }
4108 last_off = st_off + st->as_Store()->memory_size();
4109 }
4110 return true;
4111 }
4112 #endif //ASSERT
4113
4114
4115
4116
4117 //============================MergeMemNode=====================================
4118 //
4119 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
4120 // contributing store or call operations. Each contributor provides the memory
4121 // state for a particular "alias type" (see Compile::alias_type). For example,
4122 // if a MergeMem has an input X for alias category #6, then any memory reference
4123 // to alias category #6 may use X as its memory state input, as an exact equivalent
4124 // to using the MergeMem as a whole.
4125 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
4126 //
4127 // (Here, the <N> notation gives the index of the relevant adr_type.)
4128 //
4129 // In one special case (and more cases in the future), alias categories overlap.
4130 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
4131 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
4132 // it is exactly equivalent to that state W:
4133 // MergeMem(<Bot>: W) <==> W
4134 //
4135 // Usually, the merge has more than one input. In that case, where inputs
4136 // overlap (i.e., one is Bot), the narrower alias type determines the memory
4137 // state for that type, and the wider alias type (Bot) fills in everywhere else:
4138 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
4139 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
4140 //
4141 // A merge can take a "wide" memory state as one of its narrow inputs.
4142 // This simply means that the merge observes out only the relevant parts of
4143 // the wide input. That is, wide memory states arriving at narrow merge inputs
4144 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
4145 //
4146 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
4147 // and that memory slices "leak through":
4148 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
4149 //
4150 // But, in such a cascade, repeated memory slices can "block the leak":
4151 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
4152 //
4153 // In the last example, Y is not part of the combined memory state of the
4154 // outermost MergeMem. The system must, of course, prevent unschedulable
4155 // memory states from arising, so you can be sure that the state Y is somehow
4156 // a precursor to state Y'.
4157 //
4158 //
4159 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
4160 // of each MergeMemNode array are exactly the numerical alias indexes, including
4161 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
4162 // Compile::alias_type (and kin) produce and manage these indexes.
4163 //
4164 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
4165 // (Note that this provides quick access to the top node inside MergeMem methods,
4166 // without the need to reach out via TLS to Compile::current.)
4167 //
4168 // As a consequence of what was just described, a MergeMem that represents a full
4169 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
4170 // containing all alias categories.
4171 //
4172 // MergeMem nodes never (?) have control inputs, so in(0) is NULL.
4173 //
4174 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
4175 // a memory state for the alias type <N>, or else the top node, meaning that
4176 // there is no particular input for that alias type. Note that the length of
4177 // a MergeMem is variable, and may be extended at any time to accommodate new
4178 // memory states at larger alias indexes. When merges grow, they are of course
4179 // filled with "top" in the unused in() positions.
4180 //
4181 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
4182 // (Top was chosen because it works smoothly with passes like GCM.)
4183 //
4184 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
4185 // the type of random VM bits like TLS references.) Since it is always the
4186 // first non-Bot memory slice, some low-level loops use it to initialize an
4187 // index variable: for (i = AliasIdxRaw; i < req(); i++).
4188 //
4189 //
4190 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
4191 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
4192 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
4193 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
4194 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
4195 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
4196 //
4197 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
4198 // really that different from the other memory inputs. An abbreviation called
4199 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
4200 //
4201 //
4202 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
4203 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
4204 // that "emerges though" the base memory will be marked as excluding the alias types
4205 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
4206 //
4207 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
4208 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
4209 //
4210 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
4211 // (It is currently unimplemented.) As you can see, the resulting merge is
4212 // actually a disjoint union of memory states, rather than an overlay.
4213 //
4214
4215 //------------------------------MergeMemNode-----------------------------------
4216 Node* MergeMemNode::make_empty_memory() {
4217 Node* empty_memory = (Node*) Compile::current()->top();
4218 assert(empty_memory->is_top(), "correct sentinel identity");
4219 return empty_memory;
4220 }
4221
4222 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
4223 init_class_id(Class_MergeMem);
4224 // all inputs are nullified in Node::Node(int)
4225 // set_input(0, NULL); // no control input
4226
4227 // Initialize the edges uniformly to top, for starters.
4228 Node* empty_mem = make_empty_memory();
4229 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
4230 init_req(i,empty_mem);
4231 }
4232 assert(empty_memory() == empty_mem, "");
4233
4234 if( new_base != NULL && new_base->is_MergeMem() ) {
4235 MergeMemNode* mdef = new_base->as_MergeMem();
4236 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
4237 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
4238 mms.set_memory(mms.memory2());
4239 }
4240 assert(base_memory() == mdef->base_memory(), "");
4241 } else {
4242 set_base_memory(new_base);
4243 }
4244 }
4245
4246 // Make a new, untransformed MergeMem with the same base as 'mem'.
4247 // If mem is itself a MergeMem, populate the result with the same edges.
4248 MergeMemNode* MergeMemNode::make(Compile* C, Node* mem) {
4249 return new(C) MergeMemNode(mem);
4250 }
4251
4252 //------------------------------cmp--------------------------------------------
4253 uint MergeMemNode::hash() const { return NO_HASH; }
4254 uint MergeMemNode::cmp( const Node &n ) const {
4255 return (&n == this); // Always fail except on self
4256 }
4257
4258 //------------------------------Identity---------------------------------------
4259 Node* MergeMemNode::Identity(PhaseTransform *phase) {
4260 // Identity if this merge point does not record any interesting memory
4261 // disambiguations.
4262 Node* base_mem = base_memory();
4263 Node* empty_mem = empty_memory();
4264 if (base_mem != empty_mem) { // Memory path is not dead?
4265 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4266 Node* mem = in(i);
4267 if (mem != empty_mem && mem != base_mem) {
4268 return this; // Many memory splits; no change
4269 }
4270 }
4271 }
4272 return base_mem; // No memory splits; ID on the one true input
4273 }
4274
4275 //------------------------------Ideal------------------------------------------
4276 // This method is invoked recursively on chains of MergeMem nodes
4277 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4278 // Remove chain'd MergeMems
4279 //
4280 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
4281 // relative to the "in(Bot)". Since we are patching both at the same time,
4282 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
4283 // but rewrite each "in(i)" relative to the new "in(Bot)".
4284 Node *progress = NULL;
4285
4286
4287 Node* old_base = base_memory();
4288 Node* empty_mem = empty_memory();
4289 if (old_base == empty_mem)
4290 return NULL; // Dead memory path.
4291
4292 MergeMemNode* old_mbase;
4293 if (old_base != NULL && old_base->is_MergeMem())
4294 old_mbase = old_base->as_MergeMem();
4295 else
4296 old_mbase = NULL;
4297 Node* new_base = old_base;
4298
4299 // simplify stacked MergeMems in base memory
4300 if (old_mbase) new_base = old_mbase->base_memory();
4301
4302 // the base memory might contribute new slices beyond my req()
4303 if (old_mbase) grow_to_match(old_mbase);
4304
4305 // Look carefully at the base node if it is a phi.
4306 PhiNode* phi_base;
4307 if (new_base != NULL && new_base->is_Phi())
4308 phi_base = new_base->as_Phi();
4309 else
4310 phi_base = NULL;
4311
4312 Node* phi_reg = NULL;
4313 uint phi_len = (uint)-1;
4314 if (phi_base != NULL && !phi_base->is_copy()) {
4315 // do not examine phi if degraded to a copy
4316 phi_reg = phi_base->region();
4317 phi_len = phi_base->req();
4318 // see if the phi is unfinished
4319 for (uint i = 1; i < phi_len; i++) {
4320 if (phi_base->in(i) == NULL) {
4321 // incomplete phi; do not look at it yet!
4322 phi_reg = NULL;
4323 phi_len = (uint)-1;
4324 break;
4325 }
4326 }
4327 }
4328
4329 // Note: We do not call verify_sparse on entry, because inputs
4330 // can normalize to the base_memory via subsume_node or similar
4331 // mechanisms. This method repairs that damage.
4332
4333 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
4334
4335 // Look at each slice.
4336 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4337 Node* old_in = in(i);
4338 // calculate the old memory value
4339 Node* old_mem = old_in;
4340 if (old_mem == empty_mem) old_mem = old_base;
4341 assert(old_mem == memory_at(i), "");
4342
4343 // maybe update (reslice) the old memory value
4344
4345 // simplify stacked MergeMems
4346 Node* new_mem = old_mem;
4347 MergeMemNode* old_mmem;
4348 if (old_mem != NULL && old_mem->is_MergeMem())
4349 old_mmem = old_mem->as_MergeMem();
4350 else
4351 old_mmem = NULL;
4352 if (old_mmem == this) {
4353 // This can happen if loops break up and safepoints disappear.
4354 // A merge of BotPtr (default) with a RawPtr memory derived from a
4355 // safepoint can be rewritten to a merge of the same BotPtr with
4356 // the BotPtr phi coming into the loop. If that phi disappears
4357 // also, we can end up with a self-loop of the mergemem.
4358 // In general, if loops degenerate and memory effects disappear,
4359 // a mergemem can be left looking at itself. This simply means
4360 // that the mergemem's default should be used, since there is
4361 // no longer any apparent effect on this slice.
4362 // Note: If a memory slice is a MergeMem cycle, it is unreachable
4363 // from start. Update the input to TOP.
4364 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
4365 }
4366 else if (old_mmem != NULL) {
4367 new_mem = old_mmem->memory_at(i);
4368 }
4369 // else preceding memory was not a MergeMem
4370
4371 // replace equivalent phis (unfortunately, they do not GVN together)
4372 if (new_mem != NULL && new_mem != new_base &&
4373 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) {
4374 if (new_mem->is_Phi()) {
4375 PhiNode* phi_mem = new_mem->as_Phi();
4376 for (uint i = 1; i < phi_len; i++) {
4377 if (phi_base->in(i) != phi_mem->in(i)) {
4378 phi_mem = NULL;
4379 break;
4380 }
4381 }
4382 if (phi_mem != NULL) {
4383 // equivalent phi nodes; revert to the def
4384 new_mem = new_base;
4385 }
4386 }
4387 }
4388
4389 // maybe store down a new value
4390 Node* new_in = new_mem;
4391 if (new_in == new_base) new_in = empty_mem;
4392
4393 if (new_in != old_in) {
4394 // Warning: Do not combine this "if" with the previous "if"
4395 // A memory slice might have be be rewritten even if it is semantically
4396 // unchanged, if the base_memory value has changed.
4397 set_req(i, new_in);
4398 progress = this; // Report progress
4399 }
4400 }
4401
4402 if (new_base != old_base) {
4403 set_req(Compile::AliasIdxBot, new_base);
4404 // Don't use set_base_memory(new_base), because we need to update du.
4405 assert(base_memory() == new_base, "");
4406 progress = this;
4407 }
4408
4409 if( base_memory() == this ) {
4410 // a self cycle indicates this memory path is dead
4411 set_req(Compile::AliasIdxBot, empty_mem);
4412 }
4413
4414 // Resolve external cycles by calling Ideal on a MergeMem base_memory
4415 // Recursion must occur after the self cycle check above
4416 if( base_memory()->is_MergeMem() ) {
4417 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
4418 Node *m = phase->transform(new_mbase); // Rollup any cycles
4419 if( m != NULL && (m->is_top() ||
4420 m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem) ) {
4421 // propagate rollup of dead cycle to self
4422 set_req(Compile::AliasIdxBot, empty_mem);
4423 }
4424 }
4425
4426 if( base_memory() == empty_mem ) {
4427 progress = this;
4428 // Cut inputs during Parse phase only.
4429 // During Optimize phase a dead MergeMem node will be subsumed by Top.
4430 if( !can_reshape ) {
4431 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4432 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
4433 }
4434 }
4435 }
4436
4437 if( !progress && base_memory()->is_Phi() && can_reshape ) {
4438 // Check if PhiNode::Ideal's "Split phis through memory merges"
4439 // transform should be attempted. Look for this->phi->this cycle.
4440 uint merge_width = req();
4441 if (merge_width > Compile::AliasIdxRaw) {
4442 PhiNode* phi = base_memory()->as_Phi();
4443 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
4444 if (phi->in(i) == this) {
4445 phase->is_IterGVN()->_worklist.push(phi);
4446 break;
4447 }
4448 }
4449 }
4450 }
4451
4452 assert(progress || verify_sparse(), "please, no dups of base");
4453 return progress;
4454 }
4455
4456 //-------------------------set_base_memory-------------------------------------
4457 void MergeMemNode::set_base_memory(Node *new_base) {
4458 Node* empty_mem = empty_memory();
4459 set_req(Compile::AliasIdxBot, new_base);
4460 assert(memory_at(req()) == new_base, "must set default memory");
4461 // Clear out other occurrences of new_base:
4462 if (new_base != empty_mem) {
4463 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4464 if (in(i) == new_base) set_req(i, empty_mem);
4465 }
4466 }
4467 }
4468
4469 //------------------------------out_RegMask------------------------------------
4470 const RegMask &MergeMemNode::out_RegMask() const {
4471 return RegMask::Empty;
4472 }
4473
4474 //------------------------------dump_spec--------------------------------------
4475 #ifndef PRODUCT
4476 void MergeMemNode::dump_spec(outputStream *st) const {
4477 st->print(" {");
4478 Node* base_mem = base_memory();
4479 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
4480 Node* mem = memory_at(i);
4481 if (mem == base_mem) { st->print(" -"); continue; }
4482 st->print( " N%d:", mem->_idx );
4483 Compile::current()->get_adr_type(i)->dump_on(st);
4484 }
4485 st->print(" }");
4486 }
4487 #endif // !PRODUCT
4488
4489
4490 #ifdef ASSERT
4491 static bool might_be_same(Node* a, Node* b) {
4492 if (a == b) return true;
4493 if (!(a->is_Phi() || b->is_Phi())) return false;
4494 // phis shift around during optimization
4495 return true; // pretty stupid...
4496 }
4497
4498 // verify a narrow slice (either incoming or outgoing)
4499 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
4500 if (!VerifyAliases) return; // don't bother to verify unless requested
4501 if (is_error_reported()) return; // muzzle asserts when debugging an error
4502 if (Node::in_dump()) return; // muzzle asserts when printing
4503 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
4504 assert(n != NULL, "");
4505 // Elide intervening MergeMem's
4506 while (n->is_MergeMem()) {
4507 n = n->as_MergeMem()->memory_at(alias_idx);
4508 }
4509 Compile* C = Compile::current();
4510 const TypePtr* n_adr_type = n->adr_type();
4511 if (n == m->empty_memory()) {
4512 // Implicit copy of base_memory()
4513 } else if (n_adr_type != TypePtr::BOTTOM) {
4514 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type");
4515 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
4516 } else {
4517 // A few places like make_runtime_call "know" that VM calls are narrow,
4518 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
4519 bool expected_wide_mem = false;
4520 if (n == m->base_memory()) {
4521 expected_wide_mem = true;
4522 } else if (alias_idx == Compile::AliasIdxRaw ||
4523 n == m->memory_at(Compile::AliasIdxRaw)) {
4524 expected_wide_mem = true;
4525 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
4526 // memory can "leak through" calls on channels that
4527 // are write-once. Allow this also.
4528 expected_wide_mem = true;
4529 }
4530 assert(expected_wide_mem, "expected narrow slice replacement");
4531 }
4532 }
4533 #else // !ASSERT
4534 #define verify_memory_slice(m,i,n) (void)(0) // PRODUCT version is no-op
4535 #endif
4536
4537
4538 //-----------------------------memory_at---------------------------------------
4539 Node* MergeMemNode::memory_at(uint alias_idx) const {
4540 assert(alias_idx >= Compile::AliasIdxRaw ||
4541 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0,
4542 "must avoid base_memory and AliasIdxTop");
4543
4544 // Otherwise, it is a narrow slice.
4545 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
4546 Compile *C = Compile::current();
4547 if (is_empty_memory(n)) {
4548 // the array is sparse; empty slots are the "top" node
4549 n = base_memory();
4550 assert(Node::in_dump()
4551 || n == NULL || n->bottom_type() == Type::TOP
4552 || n->adr_type() == NULL // address is TOP
4553 || n->adr_type() == TypePtr::BOTTOM
4554 || n->adr_type() == TypeRawPtr::BOTTOM
4555 || Compile::current()->AliasLevel() == 0,
4556 "must be a wide memory");
4557 // AliasLevel == 0 if we are organizing the memory states manually.
4558 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
4559 } else {
4560 // make sure the stored slice is sane
4561 #ifdef ASSERT
4562 if (is_error_reported() || Node::in_dump()) {
4563 } else if (might_be_same(n, base_memory())) {
4564 // Give it a pass: It is a mostly harmless repetition of the base.
4565 // This can arise normally from node subsumption during optimization.
4566 } else {
4567 verify_memory_slice(this, alias_idx, n);
4568 }
4569 #endif
4570 }
4571 return n;
4572 }
4573
4574 //---------------------------set_memory_at-------------------------------------
4575 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
4576 verify_memory_slice(this, alias_idx, n);
4577 Node* empty_mem = empty_memory();
4578 if (n == base_memory()) n = empty_mem; // collapse default
4579 uint need_req = alias_idx+1;
4580 if (req() < need_req) {
4581 if (n == empty_mem) return; // already the default, so do not grow me
4582 // grow the sparse array
4583 do {
4584 add_req(empty_mem);
4585 } while (req() < need_req);
4586 }
4587 set_req( alias_idx, n );
4588 }
4589
4590
4591
4592 //--------------------------iteration_setup------------------------------------
4593 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
4594 if (other != NULL) {
4595 grow_to_match(other);
4596 // invariant: the finite support of mm2 is within mm->req()
4597 #ifdef ASSERT
4598 for (uint i = req(); i < other->req(); i++) {
4599 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
4600 }
4601 #endif
4602 }
4603 // Replace spurious copies of base_memory by top.
4604 Node* base_mem = base_memory();
4605 if (base_mem != NULL && !base_mem->is_top()) {
4606 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
4607 if (in(i) == base_mem)
4608 set_req(i, empty_memory());
4609 }
4610 }
4611 }
4612
4613 //---------------------------grow_to_match-------------------------------------
4614 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
4615 Node* empty_mem = empty_memory();
4616 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
4617 // look for the finite support of the other memory
4618 for (uint i = other->req(); --i >= req(); ) {
4619 if (other->in(i) != empty_mem) {
4620 uint new_len = i+1;
4621 while (req() < new_len) add_req(empty_mem);
4622 break;
4623 }
4624 }
4625 }
4626
4627 //---------------------------verify_sparse-------------------------------------
4628 #ifndef PRODUCT
4629 bool MergeMemNode::verify_sparse() const {
4630 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
4631 Node* base_mem = base_memory();
4632 // The following can happen in degenerate cases, since empty==top.
4633 if (is_empty_memory(base_mem)) return true;
4634 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4635 assert(in(i) != NULL, "sane slice");
4636 if (in(i) == base_mem) return false; // should have been the sentinel value!
4637 }
4638 return true;
4639 }
4640
4641 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
4642 Node* n;
4643 n = mm->in(idx);
4644 if (mem == n) return true; // might be empty_memory()
4645 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
4646 if (mem == n) return true;
4647 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) {
4648 if (mem == n) return true;
4649 if (n == NULL) break;
4650 }
4651 return false;
4652 }
4653 #endif // !PRODUCT