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.
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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 "gc_implementation/shenandoah/shenandoahBrooksPointer.hpp"
29 #include "memory/allocation.inline.hpp"
30 #include "oops/objArrayKlass.hpp"
31 #include "opto/addnode.hpp"
32 #include "opto/cfgnode.hpp"
33 #include "opto/compile.hpp"
34 #include "opto/connode.hpp"
35 #include "opto/loopnode.hpp"
36 #include "opto/machnode.hpp"
37 #include "opto/matcher.hpp"
38 #include "opto/memnode.hpp"
39 #include "opto/mulnode.hpp"
40 #include "opto/phaseX.hpp"
41 #include "opto/regmask.hpp"
42 #include "opto/shenandoahSupport.hpp"
43
44 // Portions of code courtesy of Clifford Click
45
46 // Optimization - Graph Style
47
48 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st);
49
50 //=============================================================================
51 uint MemNode::size_of() const { return sizeof(*this); }
52
53 const TypePtr *MemNode::adr_type() const {
54 Node* adr = in(Address);
55 const TypePtr* cross_check = NULL;
56 DEBUG_ONLY(cross_check = _adr_type);
57 return calculate_adr_type(adr->bottom_type(), cross_check);
58 }
59
60 bool MemNode::check_if_adr_maybe_raw(Node* adr) {
61 if (adr != NULL) {
62 if (adr->bottom_type()->base() == Type::RawPtr || adr->bottom_type()->base() == Type::AnyPtr) {
63 return true;
64 }
65 }
66 return false;
67 }
68
69 #ifndef PRODUCT
70 void MemNode::dump_spec(outputStream *st) const {
71 if (in(Address) == NULL) return; // node is dead
72 #ifndef ASSERT
73 // fake the missing field
74 const TypePtr* _adr_type = NULL;
75 if (in(Address) != NULL)
76 _adr_type = in(Address)->bottom_type()->isa_ptr();
77 #endif
78 dump_adr_type(this, _adr_type, st);
79
80 Compile* C = Compile::current();
81 if (C->alias_type(_adr_type)->is_volatile()) {
82 st->print(" Volatile!");
83 }
84 if (_unaligned_access) {
85 st->print(" unaligned");
86 }
87 if (_mismatched_access) {
88 st->print(" mismatched");
89 }
90 }
91
92 void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) {
93 st->print(" @");
94 if (adr_type == NULL) {
95 st->print("NULL");
96 } else {
97 adr_type->dump_on(st);
98 Compile* C = Compile::current();
99 Compile::AliasType* atp = NULL;
100 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type);
101 if (atp == NULL)
102 st->print(", idx=?\?;");
103 else if (atp->index() == Compile::AliasIdxBot)
104 st->print(", idx=Bot;");
105 else if (atp->index() == Compile::AliasIdxTop)
106 st->print(", idx=Top;");
107 else if (atp->index() == Compile::AliasIdxRaw)
108 st->print(", idx=Raw;");
109 else {
110 ciField* field = atp->field();
111 if (field) {
112 st->print(", name=");
113 field->print_name_on(st);
114 }
115 st->print(", idx=%d;", atp->index());
116 }
117 }
118 }
119
120 extern void print_alias_types();
121
122 #endif
123
124 Node *MemNode::optimize_simple_memory_chain(Node *mchain, const TypeOopPtr *t_oop, Node *load, PhaseGVN *phase) {
125 assert((t_oop != NULL), "sanity");
126 bool is_instance = t_oop->is_known_instance_field();
127 bool is_boxed_value_load = t_oop->is_ptr_to_boxed_value() &&
128 (load != NULL) && load->is_Load() &&
129 (phase->is_IterGVN() != NULL);
130 if (!(is_instance || is_boxed_value_load))
131 return mchain; // don't try to optimize non-instance types
132 uint instance_id = t_oop->instance_id();
133 Node *start_mem = phase->C->start()->proj_out(TypeFunc::Memory);
134 Node *prev = NULL;
135 Node *result = mchain;
136 while (prev != result) {
137 prev = result;
138 if (result == start_mem)
139 break; // hit one of our sentinels
140 // skip over a call which does not affect this memory slice
141 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {
142 Node *proj_in = result->in(0);
143 if (proj_in->is_Allocate() && proj_in->_idx == instance_id) {
144 break; // hit one of our sentinels
145 } else if (proj_in->is_Call()) {
146 CallNode *call = proj_in->as_Call();
147 if (!call->may_modify(t_oop, phase)) { // returns false for instances
148 result = call->in(TypeFunc::Memory);
149 }
150 } else if (proj_in->is_Initialize()) {
151 AllocateNode* alloc = proj_in->as_Initialize()->allocation();
152 // Stop if this is the initialization for the object instance which
153 // which contains this memory slice, otherwise skip over it.
154 if ((alloc == NULL) || (alloc->_idx == instance_id)) {
155 break;
156 }
157 if (is_instance) {
158 result = proj_in->in(TypeFunc::Memory);
159 } else if (is_boxed_value_load) {
160 Node* klass = alloc->in(AllocateNode::KlassNode);
161 const TypeKlassPtr* tklass = phase->type(klass)->is_klassptr();
162 if (tklass->klass_is_exact() && !tklass->klass()->equals(t_oop->klass())) {
163 result = proj_in->in(TypeFunc::Memory); // not related allocation
164 }
165 }
166 } else if (proj_in->is_MemBar()) {
167 result = proj_in->in(TypeFunc::Memory);
168 } else {
169 assert(false, "unexpected projection");
170 }
171 } else if (result->is_ClearArray()) {
172 if (!is_instance || !ClearArrayNode::step_through(&result, instance_id, phase)) {
173 // Can not bypass initialization of the instance
174 // we are looking for.
175 break;
176 }
177 // Otherwise skip it (the call updated 'result' value).
178 } else if (result->is_MergeMem()) {
179 result = step_through_mergemem(phase, result->as_MergeMem(), t_oop, NULL, tty);
180 }
181 }
182 return result;
183 }
184
185 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, Node *load, PhaseGVN *phase) {
186 const TypeOopPtr* t_oop = t_adr->isa_oopptr();
187 if (t_oop == NULL)
188 return mchain; // don't try to optimize non-oop types
189 Node* result = optimize_simple_memory_chain(mchain, t_oop, load, phase);
190 bool is_instance = t_oop->is_known_instance_field();
191 PhaseIterGVN *igvn = phase->is_IterGVN();
192 if (is_instance && igvn != NULL && result->is_Phi()) {
193 PhiNode *mphi = result->as_Phi();
194 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
195 const TypePtr *t = mphi->adr_type();
196 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
197 t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
198 t->is_oopptr()->cast_to_exactness(true)
199 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
200 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop) {
201 // clone the Phi with our address type
202 result = mphi->split_out_instance(t_adr, igvn);
203 } else {
204 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain");
205 }
206 }
207 return result;
208 }
209
210 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) {
211 uint alias_idx = phase->C->get_alias_index(tp);
212 Node *mem = mmem;
213 #ifdef ASSERT
214 {
215 // Check that current type is consistent with the alias index used during graph construction
216 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
217 bool consistent = adr_check == NULL || adr_check->empty() ||
218 phase->C->must_alias(adr_check, alias_idx );
219 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
220 if( !consistent && adr_check != NULL && !adr_check->empty() &&
221 tp->isa_aryptr() && tp->offset() == Type::OffsetBot &&
222 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot &&
223 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() ||
224 adr_check->offset() == oopDesc::klass_offset_in_bytes() ||
225 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) {
226 // don't assert if it is dead code.
227 consistent = true;
228 }
229 if( !consistent ) {
230 st->print("alias_idx==%d, adr_check==", alias_idx);
231 if( adr_check == NULL ) {
232 st->print("NULL");
233 } else {
234 adr_check->dump();
235 }
236 st->cr();
237 print_alias_types();
238 assert(consistent, "adr_check must match alias idx");
239 }
240 }
241 #endif
242 // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally
243 // means an array I have not precisely typed yet. Do not do any
244 // alias stuff with it any time soon.
245 const TypeOopPtr *toop = tp->isa_oopptr();
246 if( tp->base() != Type::AnyPtr &&
247 !(toop &&
248 toop->klass() != NULL &&
249 toop->klass()->is_java_lang_Object() &&
250 toop->offset() == Type::OffsetBot) ) {
251 // compress paths and change unreachable cycles to TOP
252 // If not, we can update the input infinitely along a MergeMem cycle
253 // Equivalent code in PhiNode::Ideal
254 Node* m = phase->transform(mmem);
255 // If transformed to a MergeMem, get the desired slice
256 // Otherwise the returned node represents memory for every slice
257 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
258 // Update input if it is progress over what we have now
259 }
260 return mem;
261 }
262
263 //--------------------------Ideal_common---------------------------------------
264 // Look for degenerate control and memory inputs. Bypass MergeMem inputs.
265 // Unhook non-raw memories from complete (macro-expanded) initializations.
266 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
267 // If our control input is a dead region, kill all below the region
268 Node *ctl = in(MemNode::Control);
269 if (ctl && remove_dead_region(phase, can_reshape))
270 return this;
271 ctl = in(MemNode::Control);
272 // Don't bother trying to transform a dead node
273 if (ctl && ctl->is_top()) return NodeSentinel;
274
275 PhaseIterGVN *igvn = phase->is_IterGVN();
276 // Wait if control on the worklist.
277 if (ctl && can_reshape && igvn != NULL) {
278 Node* bol = NULL;
279 Node* cmp = NULL;
280 if (ctl->in(0)->is_If()) {
281 assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity");
282 bol = ctl->in(0)->in(1);
283 if (bol->is_Bool())
284 cmp = ctl->in(0)->in(1)->in(1);
285 }
286 if (igvn->_worklist.member(ctl) ||
287 (bol != NULL && igvn->_worklist.member(bol)) ||
288 (cmp != NULL && igvn->_worklist.member(cmp)) ) {
289 // This control path may be dead.
290 // Delay this memory node transformation until the control is processed.
291 phase->is_IterGVN()->_worklist.push(this);
292 return NodeSentinel; // caller will return NULL
293 }
294 }
295 // Ignore if memory is dead, or self-loop
296 Node *mem = in(MemNode::Memory);
297 if (phase->type( mem ) == Type::TOP) return NodeSentinel; // caller will return NULL
298 assert(mem != this, "dead loop in MemNode::Ideal");
299
300 if (can_reshape && igvn != NULL && igvn->_worklist.member(mem)) {
301 // This memory slice may be dead.
302 // Delay this mem node transformation until the memory is processed.
303 phase->is_IterGVN()->_worklist.push(this);
304 return NodeSentinel; // caller will return NULL
305 }
306
307 Node *address = in(MemNode::Address);
308 const Type *t_adr = phase->type(address);
309 if (t_adr == Type::TOP) return NodeSentinel; // caller will return NULL
310
311 if (can_reshape && igvn != NULL &&
312 (igvn->_worklist.member(address) ||
313 igvn->_worklist.size() > 0 && (t_adr != adr_type())) ) {
314 // The address's base and type may change when the address is processed.
315 // Delay this mem node transformation until the address is processed.
316 phase->is_IterGVN()->_worklist.push(this);
317 return NodeSentinel; // caller will return NULL
318 }
319
320 // Do NOT remove or optimize the next lines: ensure a new alias index
321 // is allocated for an oop pointer type before Escape Analysis.
322 // Note: C++ will not remove it since the call has side effect.
323 if (t_adr->isa_oopptr()) {
324 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr());
325 }
326
327 Node* base = NULL;
328 if (address->is_AddP()) {
329 base = address->in(AddPNode::Base);
330 }
331 if (base != NULL && phase->type(base)->higher_equal(TypePtr::NULL_PTR) &&
332 !t_adr->isa_rawptr()) {
333 // Note: raw address has TOP base and top->higher_equal(TypePtr::NULL_PTR) is true.
334 // Skip this node optimization if its address has TOP base.
335 return NodeSentinel; // caller will return NULL
336 }
337
338 // Avoid independent memory operations
339 Node* old_mem = mem;
340
341 // The code which unhooks non-raw memories from complete (macro-expanded)
342 // initializations was removed. After macro-expansion all stores catched
343 // by Initialize node became raw stores and there is no information
344 // which memory slices they modify. So it is unsafe to move any memory
345 // operation above these stores. Also in most cases hooked non-raw memories
346 // were already unhooked by using information from detect_ptr_independence()
347 // and find_previous_store().
348
349 if (mem->is_MergeMem()) {
350 MergeMemNode* mmem = mem->as_MergeMem();
351 const TypePtr *tp = t_adr->is_ptr();
352
353 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
354 }
355
356 if (mem != old_mem) {
357 set_req(MemNode::Memory, mem);
358 if (can_reshape && old_mem->outcnt() == 0) {
359 igvn->_worklist.push(old_mem);
360 }
361 if (phase->type( mem ) == Type::TOP) return NodeSentinel;
362 return this;
363 }
364
365 // let the subclass continue analyzing...
366 return NULL;
367 }
368
369 // Helper function for proving some simple control dominations.
370 // Attempt to prove that all control inputs of 'dom' dominate 'sub'.
371 // Already assumes that 'dom' is available at 'sub', and that 'sub'
372 // is not a constant (dominated by the method's StartNode).
373 // Used by MemNode::find_previous_store to prove that the
374 // control input of a memory operation predates (dominates)
375 // an allocation it wants to look past.
376 bool MemNode::all_controls_dominate(Node* dom, Node* sub) {
377 if (dom == NULL || dom->is_top() || sub == NULL || sub->is_top())
378 return false; // Conservative answer for dead code
379
380 // Check 'dom'. Skip Proj and CatchProj nodes.
381 dom = dom->find_exact_control(dom);
382 if (dom == NULL || dom->is_top())
383 return false; // Conservative answer for dead code
384
385 if (dom == sub) {
386 // For the case when, for example, 'sub' is Initialize and the original
387 // 'dom' is Proj node of the 'sub'.
388 return false;
389 }
390
391 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub)
392 return true;
393
394 // 'dom' dominates 'sub' if its control edge and control edges
395 // of all its inputs dominate or equal to sub's control edge.
396
397 // Currently 'sub' is either Allocate, Initialize or Start nodes.
398 // Or Region for the check in LoadNode::Ideal();
399 // 'sub' should have sub->in(0) != NULL.
400 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() ||
401 sub->is_Region() || sub->is_Call(), "expecting only these nodes");
402
403 // Get control edge of 'sub'.
404 Node* orig_sub = sub;
405 sub = sub->find_exact_control(sub->in(0));
406 if (sub == NULL || sub->is_top())
407 return false; // Conservative answer for dead code
408
409 assert(sub->is_CFG(), "expecting control");
410
411 if (sub == dom)
412 return true;
413
414 if (sub->is_Start() || sub->is_Root())
415 return false;
416
417 {
418 // Check all control edges of 'dom'.
419
420 ResourceMark rm;
421 Arena* arena = Thread::current()->resource_area();
422 Node_List nlist(arena);
423 Unique_Node_List dom_list(arena);
424
425 dom_list.push(dom);
426 bool only_dominating_controls = false;
427
428 for (uint next = 0; next < dom_list.size(); next++) {
429 Node* n = dom_list.at(next);
430 if (n == orig_sub)
431 return false; // One of dom's inputs dominated by sub.
432 if (!n->is_CFG() && n->pinned()) {
433 // Check only own control edge for pinned non-control nodes.
434 n = n->find_exact_control(n->in(0));
435 if (n == NULL || n->is_top())
436 return false; // Conservative answer for dead code
437 assert(n->is_CFG(), "expecting control");
438 dom_list.push(n);
439 } else if (n->is_Con() || n->is_Start() || n->is_Root()) {
440 only_dominating_controls = true;
441 } else if (n->is_CFG()) {
442 if (n->dominates(sub, nlist))
443 only_dominating_controls = true;
444 else
445 return false;
446 } else {
447 // First, own control edge.
448 Node* m = n->find_exact_control(n->in(0));
449 if (m != NULL) {
450 if (m->is_top())
451 return false; // Conservative answer for dead code
452 dom_list.push(m);
453 }
454 // Now, the rest of edges.
455 uint cnt = n->req();
456 for (uint i = 1; i < cnt; i++) {
457 m = n->find_exact_control(n->in(i));
458 if (m == NULL || m->is_top())
459 continue;
460 dom_list.push(m);
461 }
462 }
463 }
464 return only_dominating_controls;
465 }
466 }
467
468 //---------------------detect_ptr_independence---------------------------------
469 // Used by MemNode::find_previous_store to prove that two base
470 // pointers are never equal.
471 // The pointers are accompanied by their associated allocations,
472 // if any, which have been previously discovered by the caller.
473 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
474 Node* p2, AllocateNode* a2,
475 PhaseTransform* phase) {
476 // Attempt to prove that these two pointers cannot be aliased.
477 // They may both manifestly be allocations, and they should differ.
478 // Or, if they are not both allocations, they can be distinct constants.
479 // Otherwise, one is an allocation and the other a pre-existing value.
480 if (a1 == NULL && a2 == NULL) { // neither an allocation
481 return (p1 != p2) && p1->is_Con() && p2->is_Con();
482 } else if (a1 != NULL && a2 != NULL) { // both allocations
483 return (a1 != a2);
484 } else if (a1 != NULL) { // one allocation a1
485 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.)
486 return all_controls_dominate(p2, a1);
487 } else { //(a2 != NULL) // one allocation a2
488 return all_controls_dominate(p1, a2);
489 }
490 return false;
491 }
492
493
494 // The logic for reordering loads and stores uses four steps:
495 // (a) Walk carefully past stores and initializations which we
496 // can prove are independent of this load.
497 // (b) Observe that the next memory state makes an exact match
498 // with self (load or store), and locate the relevant store.
499 // (c) Ensure that, if we were to wire self directly to the store,
500 // the optimizer would fold it up somehow.
501 // (d) Do the rewiring, and return, depending on some other part of
502 // the optimizer to fold up the load.
503 // This routine handles steps (a) and (b). Steps (c) and (d) are
504 // specific to loads and stores, so they are handled by the callers.
505 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.)
506 //
507 Node* MemNode::find_previous_store(PhaseTransform* phase) {
508 Node* ctrl = in(MemNode::Control);
509 Node* adr = in(MemNode::Address);
510 intptr_t offset = 0;
511 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
512 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase);
513
514 if (offset == Type::OffsetBot)
515 return NULL; // cannot unalias unless there are precise offsets
516
517 const bool adr_maybe_raw = check_if_adr_maybe_raw(adr);
518 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr();
519
520 intptr_t size_in_bytes = memory_size();
521
522 Node* mem = in(MemNode::Memory); // start searching here...
523
524 int cnt = 50; // Cycle limiter
525 for (;;) { // While we can dance past unrelated stores...
526 if (--cnt < 0) break; // Caught in cycle or a complicated dance?
527
528 if (mem->is_Store()) {
529 Node* st_adr = mem->in(MemNode::Address);
530 intptr_t st_offset = 0;
531 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
532 if (st_base == NULL)
533 break; // inscrutable pointer
534
535 // For raw accesses it's not enough to prove that constant offsets don't intersect.
536 // We need the bases to be the equal in order for the offset check to make sense.
537 if ((adr_maybe_raw || check_if_adr_maybe_raw(st_adr)) && st_base != base) {
538 break;
539 }
540
541 if (st_offset != offset && st_offset != Type::OffsetBot) {
542 const int MAX_STORE = BytesPerLong;
543 if (st_offset >= offset + size_in_bytes ||
544 st_offset <= offset - MAX_STORE ||
545 st_offset <= offset - mem->as_Store()->memory_size()) {
546 // Success: The offsets are provably independent.
547 // (You may ask, why not just test st_offset != offset and be done?
548 // The answer is that stores of different sizes can co-exist
549 // in the same sequence of RawMem effects. We sometimes initialize
550 // a whole 'tile' of array elements with a single jint or jlong.)
551 mem = mem->in(MemNode::Memory);
552 continue; // (a) advance through independent store memory
553 }
554 }
555 if (st_base != base &&
556 detect_ptr_independence(base, alloc,
557 st_base,
558 AllocateNode::Ideal_allocation(st_base, phase),
559 phase)) {
560 // Success: The bases are provably independent.
561 mem = mem->in(MemNode::Memory);
562 continue; // (a) advance through independent store memory
563 }
564
565 // (b) At this point, if the bases or offsets do not agree, we lose,
566 // since we have not managed to prove 'this' and 'mem' independent.
567 if (st_base == base && st_offset == offset) {
568 return mem; // let caller handle steps (c), (d)
569 }
570
571 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
572 InitializeNode* st_init = mem->in(0)->as_Initialize();
573 AllocateNode* st_alloc = st_init->allocation();
574 if (st_alloc == NULL)
575 break; // something degenerated
576 bool known_identical = false;
577 bool known_independent = false;
578 if (alloc == st_alloc)
579 known_identical = true;
580 else if (alloc != NULL)
581 known_independent = true;
582 else if (all_controls_dominate(this, st_alloc))
583 known_independent = true;
584
585 if (known_independent) {
586 // The bases are provably independent: Either they are
587 // manifestly distinct allocations, or else the control
588 // of this load dominates the store's allocation.
589 int alias_idx = phase->C->get_alias_index(adr_type());
590 if (alias_idx == Compile::AliasIdxRaw) {
591 mem = st_alloc->in(TypeFunc::Memory);
592 } else {
593 mem = st_init->memory(alias_idx);
594 }
595 continue; // (a) advance through independent store memory
596 }
597
598 // (b) at this point, if we are not looking at a store initializing
599 // the same allocation we are loading from, we lose.
600 if (known_identical) {
601 // From caller, can_see_stored_value will consult find_captured_store.
602 return mem; // let caller handle steps (c), (d)
603 }
604
605 } else if (addr_t != NULL && addr_t->is_known_instance_field()) {
606 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
607 if (mem->is_Proj() && mem->in(0)->is_Call()) {
608 CallNode *call = mem->in(0)->as_Call();
609 if (!call->may_modify(addr_t, phase)) {
610 mem = call->in(TypeFunc::Memory);
611 continue; // (a) advance through independent call memory
612 }
613 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) {
614 mem = mem->in(0)->in(TypeFunc::Memory);
615 continue; // (a) advance through independent MemBar memory
616 } else if (mem->is_ClearArray()) {
617 if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) {
618 // (the call updated 'mem' value)
619 continue; // (a) advance through independent allocation memory
620 } else {
621 // Can not bypass initialization of the instance
622 // we are looking for.
623 return mem;
624 }
625 } else if (mem->is_MergeMem()) {
626 int alias_idx = phase->C->get_alias_index(adr_type());
627 mem = mem->as_MergeMem()->memory_at(alias_idx);
628 continue; // (a) advance through independent MergeMem memory
629 }
630 }
631
632 // Unless there is an explicit 'continue', we must bail out here,
633 // because 'mem' is an inscrutable memory state (e.g., a call).
634 break;
635 }
636
637 return NULL; // bail out
638 }
639
640 //----------------------calculate_adr_type-------------------------------------
641 // Helper function. Notices when the given type of address hits top or bottom.
642 // Also, asserts a cross-check of the type against the expected address type.
643 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
644 if (t == Type::TOP) return NULL; // does not touch memory any more?
645 #ifdef PRODUCT
646 cross_check = NULL;
647 #else
648 if (!VerifyAliases || is_error_reported() || Node::in_dump()) cross_check = NULL;
649 #endif
650 const TypePtr* tp = t->isa_ptr();
651 if (tp == NULL) {
652 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
653 return TypePtr::BOTTOM; // touches lots of memory
654 } else {
655 #ifdef ASSERT
656 // %%%% [phh] We don't check the alias index if cross_check is
657 // TypeRawPtr::BOTTOM. Needs to be investigated.
658 if (cross_check != NULL &&
659 cross_check != TypePtr::BOTTOM &&
660 cross_check != TypeRawPtr::BOTTOM) {
661 // Recheck the alias index, to see if it has changed (due to a bug).
662 Compile* C = Compile::current();
663 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
664 "must stay in the original alias category");
665 // The type of the address must be contained in the adr_type,
666 // disregarding "null"-ness.
667 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
668 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
669 assert(cross_check->meet(tp_notnull) == cross_check->remove_speculative(),
670 "real address must not escape from expected memory type");
671 }
672 #endif
673 return tp;
674 }
675 }
676
677 //=============================================================================
678 // Should LoadNode::Ideal() attempt to remove control edges?
679 bool LoadNode::can_remove_control() const {
680 return true;
681 }
682 uint LoadNode::size_of() const { return sizeof(*this); }
683 uint LoadNode::cmp( const Node &n ) const
684 { return !Type::cmp( _type, ((LoadNode&)n)._type ); }
685 const Type *LoadNode::bottom_type() const { return _type; }
686 uint LoadNode::ideal_reg() const {
687 return _type->ideal_reg();
688 }
689
690 #ifndef PRODUCT
691 void LoadNode::dump_spec(outputStream *st) const {
692 MemNode::dump_spec(st);
693 if( !Verbose && !WizardMode ) {
694 // standard dump does this in Verbose and WizardMode
695 st->print(" #"); _type->dump_on(st);
696 }
697 if (!_depends_only_on_test) {
698 st->print(" (does not depend only on test)");
699 }
700 }
701 #endif
702
703 #ifdef ASSERT
704 //----------------------------is_immutable_value-------------------------------
705 // Helper function to allow a raw load without control edge for some cases
706 bool LoadNode::is_immutable_value(Node* adr) {
707 return (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() &&
708 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal &&
709 (adr->in(AddPNode::Offset)->find_intptr_t_con(-1) ==
710 in_bytes(JavaThread::osthread_offset())));
711 }
712 #endif
713
714 //----------------------------LoadNode::make-----------------------------------
715 // Polymorphic factory method:
716 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) {
717 Compile* C = gvn.C;
718
719 // sanity check the alias category against the created node type
720 assert(!(adr_type->isa_oopptr() &&
721 adr_type->offset() == oopDesc::klass_offset_in_bytes()),
722 "use LoadKlassNode instead");
723 assert(!(adr_type->isa_aryptr() &&
724 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
725 "use LoadRangeNode instead");
726 // Check control edge of raw loads
727 assert( ctl != NULL || C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
728 // oop will be recorded in oop map if load crosses safepoint
729 rt->isa_oopptr() || is_immutable_value(adr),
730 "raw memory operations should have control edge");
731 switch (bt) {
732 case T_BOOLEAN: return new (C) LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency);
733 case T_BYTE: return new (C) LoadBNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency);
734 case T_INT: return new (C) LoadINode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency);
735 case T_CHAR: return new (C) LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency);
736 case T_SHORT: return new (C) LoadSNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency);
737 case T_LONG: return new (C) LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency);
738 case T_FLOAT: return new (C) LoadFNode (ctl, mem, adr, adr_type, rt, mo, control_dependency);
739 case T_DOUBLE: return new (C) LoadDNode (ctl, mem, adr, adr_type, rt, mo, control_dependency);
740 case T_ADDRESS: return new (C) LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency);
741 case T_OBJECT:
742 #ifdef _LP64
743 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
744 Node* load = gvn.transform(new (C) LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo, control_dependency));
745 return new (C) DecodeNNode(load, load->bottom_type()->make_ptr());
746 } else
747 #endif
748 {
749 assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop");
750 return new (C) LoadPNode(ctl, mem, adr, adr_type, rt->is_oopptr(), mo, control_dependency);
751 }
752 }
753 ShouldNotReachHere();
754 return (LoadNode*)NULL;
755 }
756
757 LoadLNode* LoadLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo, ControlDependency control_dependency) {
758 bool require_atomic = true;
759 return new (C) LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency, require_atomic);
760 }
761
762 LoadDNode* LoadDNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo, ControlDependency control_dependency) {
763 bool require_atomic = true;
764 return new (C) LoadDNode(ctl, mem, adr, adr_type, rt, mo, control_dependency, require_atomic);
765 }
766
767
768
769 //------------------------------hash-------------------------------------------
770 uint LoadNode::hash() const {
771 // unroll addition of interesting fields
772 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
773 }
774
775 static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) {
776 if ((atp != NULL) && (atp->index() >= Compile::AliasIdxRaw)) {
777 bool non_volatile = (atp->field() != NULL) && !atp->field()->is_volatile();
778 bool is_stable_ary = FoldStableValues &&
779 (tp != NULL) && (tp->isa_aryptr() != NULL) &&
780 tp->isa_aryptr()->is_stable();
781
782 return (eliminate_boxing && non_volatile) || is_stable_ary;
783 }
784
785 return false;
786 }
787
788 //---------------------------can_see_stored_value------------------------------
789 // This routine exists to make sure this set of tests is done the same
790 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
791 // will change the graph shape in a way which makes memory alive twice at the
792 // same time (uses the Oracle model of aliasing), then some
793 // LoadXNode::Identity will fold things back to the equivalence-class model
794 // of aliasing.
795 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const {
796 Node* ld_adr = in(MemNode::Address);
797 intptr_t ld_off = 0;
798 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
799 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
800 Compile::AliasType* atp = (tp != NULL) ? phase->C->alias_type(tp) : NULL;
801 // This is more general than load from boxing objects.
802 if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) {
803 uint alias_idx = atp->index();
804 bool final = !atp->is_rewritable();
805 Node* result = NULL;
806 Node* current = st;
807 // Skip through chains of MemBarNodes checking the MergeMems for
808 // new states for the slice of this load. Stop once any other
809 // kind of node is encountered. Loads from final memory can skip
810 // through any kind of MemBar but normal loads shouldn't skip
811 // through MemBarAcquire since the could allow them to move out of
812 // a synchronized region.
813 while (current->is_Proj()) {
814 int opc = current->in(0)->Opcode();
815 if ((final && (opc == Op_MemBarAcquire ||
816 opc == Op_MemBarAcquireLock ||
817 opc == Op_LoadFence)) ||
818 opc == Op_MemBarRelease ||
819 opc == Op_StoreFence ||
820 opc == Op_MemBarReleaseLock ||
821 opc == Op_MemBarCPUOrder) {
822 Node* mem = current->in(0)->in(TypeFunc::Memory);
823 if (mem->is_MergeMem()) {
824 MergeMemNode* merge = mem->as_MergeMem();
825 Node* new_st = merge->memory_at(alias_idx);
826 if (new_st == merge->base_memory()) {
827 // Keep searching
828 current = new_st;
829 continue;
830 }
831 // Save the new memory state for the slice and fall through
832 // to exit.
833 result = new_st;
834 }
835 }
836 break;
837 }
838 if (result != NULL) {
839 st = result;
840 }
841 }
842
843 // Loop around twice in the case Load -> Initialize -> Store.
844 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
845 for (int trip = 0; trip <= 1; trip++) {
846
847 if (st->is_Store()) {
848 Node* st_adr = st->in(MemNode::Address);
849 if (!phase->eqv(st_adr, ld_adr)) {
850 // Try harder before giving up... Match raw and non-raw pointers.
851 intptr_t st_off = 0;
852 AllocateNode* alloc = AllocateNode::Ideal_allocation(st_adr, phase, st_off);
853 if (alloc == NULL) return NULL;
854 if (alloc != ld_alloc) return NULL;
855 if (ld_off != st_off) return NULL;
856 // At this point we have proven something like this setup:
857 // A = Allocate(...)
858 // L = LoadQ(, AddP(CastPP(, A.Parm),, #Off))
859 // S = StoreQ(, AddP(, A.Parm , #Off), V)
860 // (Actually, we haven't yet proven the Q's are the same.)
861 // In other words, we are loading from a casted version of
862 // the same pointer-and-offset that we stored to.
863 // Thus, we are able to replace L by V.
864 }
865 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
866 if (store_Opcode() != st->Opcode())
867 return NULL;
868 return st->in(MemNode::ValueIn);
869 }
870
871 // A load from a freshly-created object always returns zero.
872 // (This can happen after LoadNode::Ideal resets the load's memory input
873 // to find_captured_store, which returned InitializeNode::zero_memory.)
874 if (st->is_Proj() && st->in(0)->is_Allocate() &&
875 (st->in(0) == ld_alloc) &&
876 (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) {
877 // return a zero value for the load's basic type
878 // (This is one of the few places where a generic PhaseTransform
879 // can create new nodes. Think of it as lazily manifesting
880 // virtually pre-existing constants.)
881 return phase->zerocon(memory_type());
882 }
883
884 // A load from an initialization barrier can match a captured store.
885 if (st->is_Proj() && st->in(0)->is_Initialize()) {
886 InitializeNode* init = st->in(0)->as_Initialize();
887 AllocateNode* alloc = init->allocation();
888 if ((alloc != NULL) && (alloc == ld_alloc)) {
889 // examine a captured store value
890 st = init->find_captured_store(ld_off, memory_size(), phase);
891 if (st != NULL)
892 continue; // take one more trip around
893 }
894 }
895
896 // Load boxed value from result of valueOf() call is input parameter.
897 if (this->is_Load() && ld_adr->is_AddP() &&
898 (tp != NULL) && tp->is_ptr_to_boxed_value()) {
899 intptr_t ignore = 0;
900 Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore);
901 base = ShenandoahBarrierNode::skip_through_barrier(base);
902 if (base != NULL && base->is_Proj() &&
903 base->as_Proj()->_con == TypeFunc::Parms &&
904 base->in(0)->is_CallStaticJava() &&
905 base->in(0)->as_CallStaticJava()->is_boxing_method()) {
906 return base->in(0)->in(TypeFunc::Parms);
907 }
908 }
909
910 break;
911 }
912
913 return NULL;
914 }
915
916 //----------------------is_instance_field_load_with_local_phi------------------
917 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
918 if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl &&
919 in(Address)->is_AddP() ) {
920 const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr();
921 // Only instances and boxed values.
922 if( t_oop != NULL &&
923 (t_oop->is_ptr_to_boxed_value() ||
924 t_oop->is_known_instance_field()) &&
925 t_oop->offset() != Type::OffsetBot &&
926 t_oop->offset() != Type::OffsetTop) {
927 return true;
928 }
929 }
930 return false;
931 }
932
933 //------------------------------Identity---------------------------------------
934 // Loads are identity if previous store is to same address
935 Node *LoadNode::Identity( PhaseTransform *phase ) {
936 // If the previous store-maker is the right kind of Store, and the store is
937 // to the same address, then we are equal to the value stored.
938 Node* mem = in(Memory);
939 Node* value = can_see_stored_value(mem, phase);
940 if( value ) {
941 // byte, short & char stores truncate naturally.
942 // A load has to load the truncated value which requires
943 // some sort of masking operation and that requires an
944 // Ideal call instead of an Identity call.
945 if (memory_size() < BytesPerInt) {
946 // If the input to the store does not fit with the load's result type,
947 // it must be truncated via an Ideal call.
948 if (!phase->type(value)->higher_equal(phase->type(this)))
949 return this;
950 }
951 PhaseIterGVN* igvn = phase->is_IterGVN();
952 if (UseShenandoahGC &&
953 igvn != NULL &&
954 value->is_Phi() &&
955 value->req() > 2 &&
956 value->in(1) != NULL &&
957 value->in(1)->is_ShenandoahBarrier()) {
958 if (igvn->_worklist.member(value) ||
959 igvn->_worklist.member(value->in(0)) ||
960 (value->in(0)->in(1) != NULL &&
961 value->in(0)->in(1)->is_IfProj() &&
962 (igvn->_worklist.member(value->in(0)->in(1)) ||
963 (value->in(0)->in(1)->in(0) != NULL &&
964 igvn->_worklist.member(value->in(0)->in(1)->in(0)))))) {
965 igvn->_worklist.push(this);
966 return this;
967 }
968 }
969 // (This works even when value is a Con, but LoadNode::Value
970 // usually runs first, producing the singleton type of the Con.)
971 if (UseShenandoahGC) {
972 Node* value_no_barrier = ShenandoahBarrierNode::skip_through_barrier(value->Opcode() == Op_EncodeP ? value->in(1) : value);
973 if (value->Opcode() == Op_EncodeP) {
974 if (value_no_barrier != value->in(1)) {
975 Node* encode = value->clone();
976 encode->set_req(1, value_no_barrier);
977 encode = phase->transform(encode);
978 return encode;
979 }
980 } else {
981 return value_no_barrier;
982 }
983 }
984
985 return value;
986 }
987
988 // Search for an existing data phi which was generated before for the same
989 // instance's field to avoid infinite generation of phis in a loop.
990 Node *region = mem->in(0);
991 if (is_instance_field_load_with_local_phi(region)) {
992 const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr();
993 int this_index = phase->C->get_alias_index(addr_t);
994 int this_offset = addr_t->offset();
995 int this_iid = addr_t->instance_id();
996 if (!addr_t->is_known_instance() &&
997 addr_t->is_ptr_to_boxed_value()) {
998 // Use _idx of address base (could be Phi node) for boxed values.
999 intptr_t ignore = 0;
1000 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1001 if (base == NULL) {
1002 return this;
1003 }
1004 this_iid = base->_idx;
1005 }
1006 const Type* this_type = bottom_type();
1007 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1008 Node* phi = region->fast_out(i);
1009 if (phi->is_Phi() && phi != mem &&
1010 phi->as_Phi()->is_same_inst_field(this_type, (int)mem->_idx, this_iid, this_index, this_offset)) {
1011 return phi;
1012 }
1013 }
1014 }
1015
1016 return this;
1017 }
1018
1019 // We're loading from an object which has autobox behaviour.
1020 // If this object is result of a valueOf call we'll have a phi
1021 // merging a newly allocated object and a load from the cache.
1022 // We want to replace this load with the original incoming
1023 // argument to the valueOf call.
1024 Node* LoadNode::eliminate_autobox(PhaseGVN* phase) {
1025 assert(phase->C->eliminate_boxing(), "sanity");
1026 intptr_t ignore = 0;
1027 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1028 if ((base == NULL) || base->is_Phi()) {
1029 // Push the loads from the phi that comes from valueOf up
1030 // through it to allow elimination of the loads and the recovery
1031 // of the original value. It is done in split_through_phi().
1032 return NULL;
1033 } else if (base->is_Load() ||
1034 base->is_DecodeN() && base->in(1)->is_Load()) {
1035 // Eliminate the load of boxed value for integer types from the cache
1036 // array by deriving the value from the index into the array.
1037 // Capture the offset of the load and then reverse the computation.
1038
1039 // Get LoadN node which loads a boxing object from 'cache' array.
1040 if (base->is_DecodeN()) {
1041 base = base->in(1);
1042 }
1043 if (!base->in(Address)->is_AddP()) {
1044 return NULL; // Complex address
1045 }
1046 AddPNode* address = base->in(Address)->as_AddP();
1047 Node* cache_base = ShenandoahBarrierNode::skip_through_barrier(address->in(AddPNode::Base));
1048 if ((cache_base != NULL) && cache_base->is_DecodeN()) {
1049 // Get ConP node which is static 'cache' field.
1050 cache_base = cache_base->in(1);
1051 }
1052 if ((cache_base != NULL) && cache_base->is_Con()) {
1053 const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr();
1054 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1055 Node* elements[4];
1056 int shift = exact_log2(type2aelembytes(T_OBJECT));
1057 int count = address->unpack_offsets(elements, ARRAY_SIZE(elements));
1058 if ((count > 0) && elements[0]->is_Con() &&
1059 ((count == 1) ||
1060 (count == 2) && elements[1]->Opcode() == Op_LShiftX &&
1061 elements[1]->in(2) == phase->intcon(shift))) {
1062 ciObjArray* array = base_type->const_oop()->as_obj_array();
1063 // Fetch the box object cache[0] at the base of the array and get its value
1064 ciInstance* box = array->obj_at(0)->as_instance();
1065 ciInstanceKlass* ik = box->klass()->as_instance_klass();
1066 assert(ik->is_box_klass(), "sanity");
1067 assert(ik->nof_nonstatic_fields() == 1, "change following code");
1068 if (ik->nof_nonstatic_fields() == 1) {
1069 // This should be true nonstatic_field_at requires calling
1070 // nof_nonstatic_fields so check it anyway
1071 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1072 BasicType bt = c.basic_type();
1073 // Only integer types have boxing cache.
1074 assert(bt == T_BOOLEAN || bt == T_CHAR ||
1075 bt == T_BYTE || bt == T_SHORT ||
1076 bt == T_INT || bt == T_LONG, err_msg_res("wrong type = %s", type2name(bt)));
1077 jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int();
1078 if (cache_low != (int)cache_low) {
1079 return NULL; // should not happen since cache is array indexed by value
1080 }
1081 jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift);
1082 if (offset != (int)offset) {
1083 return NULL; // should not happen since cache is array indexed by value
1084 }
1085 // Add up all the offsets making of the address of the load
1086 Node* result = elements[0];
1087 for (int i = 1; i < count; i++) {
1088 result = phase->transform(new (phase->C) AddXNode(result, elements[i]));
1089 }
1090 // Remove the constant offset from the address and then
1091 result = phase->transform(new (phase->C) AddXNode(result, phase->MakeConX(-(int)offset)));
1092 // remove the scaling of the offset to recover the original index.
1093 if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) {
1094 // Peel the shift off directly but wrap it in a dummy node
1095 // since Ideal can't return existing nodes
1096 result = new (phase->C) RShiftXNode(result->in(1), phase->intcon(0));
1097 } else if (result->is_Add() && result->in(2)->is_Con() &&
1098 result->in(1)->Opcode() == Op_LShiftX &&
1099 result->in(1)->in(2) == phase->intcon(shift)) {
1100 // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z)
1101 // but for boxing cache access we know that X<<Z will not overflow
1102 // (there is range check) so we do this optimizatrion by hand here.
1103 Node* add_con = new (phase->C) RShiftXNode(result->in(2), phase->intcon(shift));
1104 result = new (phase->C) AddXNode(result->in(1)->in(1), phase->transform(add_con));
1105 } else {
1106 result = new (phase->C) RShiftXNode(result, phase->intcon(shift));
1107 }
1108 #ifdef _LP64
1109 if (bt != T_LONG) {
1110 result = new (phase->C) ConvL2INode(phase->transform(result));
1111 }
1112 #else
1113 if (bt == T_LONG) {
1114 result = new (phase->C) ConvI2LNode(phase->transform(result));
1115 }
1116 #endif
1117 // Boxing/unboxing can be done from signed & unsigned loads (e.g. LoadUB -> ... -> LoadB pair).
1118 // Need to preserve unboxing load type if it is unsigned.
1119 switch(this->Opcode()) {
1120 case Op_LoadUB:
1121 result = new (phase->C) AndINode(phase->transform(result), phase->intcon(0xFF));
1122 break;
1123 case Op_LoadUS:
1124 result = new (phase->C) AndINode(phase->transform(result), phase->intcon(0xFFFF));
1125 break;
1126 }
1127 return result;
1128 }
1129 }
1130 }
1131 }
1132 }
1133 return NULL;
1134 }
1135
1136 static bool stable_phi(PhiNode* phi, PhaseGVN *phase) {
1137 Node* region = phi->in(0);
1138 if (region == NULL) {
1139 return false; // Wait stable graph
1140 }
1141 uint cnt = phi->req();
1142 for (uint i = 1; i < cnt; i++) {
1143 Node* rc = region->in(i);
1144 if (rc == NULL || phase->type(rc) == Type::TOP)
1145 return false; // Wait stable graph
1146 Node* in = phi->in(i);
1147 if (in == NULL || phase->type(in) == Type::TOP)
1148 return false; // Wait stable graph
1149 }
1150 return true;
1151 }
1152 //------------------------------split_through_phi------------------------------
1153 // Split instance or boxed field load through Phi.
1154 Node *LoadNode::split_through_phi(PhaseGVN *phase) {
1155 Node* mem = in(Memory);
1156 Node* address = in(Address);
1157 const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr();
1158
1159 assert((t_oop != NULL) &&
1160 (t_oop->is_known_instance_field() ||
1161 t_oop->is_ptr_to_boxed_value()), "invalide conditions");
1162
1163 Compile* C = phase->C;
1164 intptr_t ignore = 0;
1165 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1166 bool base_is_phi = (base != NULL) && base->is_Phi();
1167 bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() &&
1168 (base != NULL) && (base == address->in(AddPNode::Base)) &&
1169 phase->type(base)->higher_equal(TypePtr::NOTNULL);
1170
1171 if (!((mem->is_Phi() || base_is_phi) &&
1172 (load_boxed_values || t_oop->is_known_instance_field()))) {
1173 return NULL; // memory is not Phi
1174 }
1175
1176 if (mem->is_Phi()) {
1177 if (!stable_phi(mem->as_Phi(), phase)) {
1178 return NULL; // Wait stable graph
1179 }
1180 uint cnt = mem->req();
1181 // Check for loop invariant memory.
1182 if (cnt == 3) {
1183 for (uint i = 1; i < cnt; i++) {
1184 Node* in = mem->in(i);
1185 Node* m = optimize_memory_chain(in, t_oop, this, phase);
1186 if (m == mem) {
1187 set_req(Memory, mem->in(cnt - i));
1188 return this; // made change
1189 }
1190 }
1191 }
1192 }
1193 if (base_is_phi) {
1194 if (!stable_phi(base->as_Phi(), phase)) {
1195 return NULL; // Wait stable graph
1196 }
1197 uint cnt = base->req();
1198 // Check for loop invariant memory.
1199 if (cnt == 3) {
1200 for (uint i = 1; i < cnt; i++) {
1201 if (base->in(i) == base) {
1202 return NULL; // Wait stable graph
1203 }
1204 }
1205 }
1206 }
1207
1208 bool load_boxed_phi = load_boxed_values && base_is_phi && (base->in(0) == mem->in(0));
1209
1210 // Split through Phi (see original code in loopopts.cpp).
1211 assert(C->have_alias_type(t_oop), "instance should have alias type");
1212
1213 // Do nothing here if Identity will find a value
1214 // (to avoid infinite chain of value phis generation).
1215 if (!phase->eqv(this, this->Identity(phase)))
1216 return NULL;
1217
1218 // Select Region to split through.
1219 Node* region;
1220 if (!base_is_phi) {
1221 assert(mem->is_Phi(), "sanity");
1222 region = mem->in(0);
1223 // Skip if the region dominates some control edge of the address.
1224 if (!MemNode::all_controls_dominate(address, region))
1225 return NULL;
1226 } else if (!mem->is_Phi()) {
1227 assert(base_is_phi, "sanity");
1228 region = base->in(0);
1229 // Skip if the region dominates some control edge of the memory.
1230 if (!MemNode::all_controls_dominate(mem, region))
1231 return NULL;
1232 } else if (base->in(0) != mem->in(0)) {
1233 assert(base_is_phi && mem->is_Phi(), "sanity");
1234 if (MemNode::all_controls_dominate(mem, base->in(0))) {
1235 region = base->in(0);
1236 } else if (MemNode::all_controls_dominate(address, mem->in(0))) {
1237 region = mem->in(0);
1238 } else {
1239 return NULL; // complex graph
1240 }
1241 } else {
1242 assert(base->in(0) == mem->in(0), "sanity");
1243 region = mem->in(0);
1244 }
1245
1246 const Type* this_type = this->bottom_type();
1247 int this_index = C->get_alias_index(t_oop);
1248 int this_offset = t_oop->offset();
1249 int this_iid = t_oop->instance_id();
1250 if (!t_oop->is_known_instance() && load_boxed_values) {
1251 // Use _idx of address base for boxed values.
1252 this_iid = base->_idx;
1253 }
1254 PhaseIterGVN* igvn = phase->is_IterGVN();
1255 Node* phi = new (C) PhiNode(region, this_type, NULL, mem->_idx, this_iid, this_index, this_offset);
1256 for (uint i = 1; i < region->req(); i++) {
1257 Node* x;
1258 Node* the_clone = NULL;
1259 if (region->in(i) == C->top()) {
1260 x = C->top(); // Dead path? Use a dead data op
1261 } else {
1262 x = this->clone(); // Else clone up the data op
1263 the_clone = x; // Remember for possible deletion.
1264 // Alter data node to use pre-phi inputs
1265 if (this->in(0) == region) {
1266 x->set_req(0, region->in(i));
1267 } else {
1268 x->set_req(0, NULL);
1269 }
1270 if (mem->is_Phi() && (mem->in(0) == region)) {
1271 x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone.
1272 }
1273 if (address->is_Phi() && address->in(0) == region) {
1274 x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone
1275 }
1276 if (base_is_phi && (base->in(0) == region)) {
1277 Node* base_x = base->in(i); // Clone address for loads from boxed objects.
1278 Node* adr_x = phase->transform(new (C) AddPNode(base_x,base_x,address->in(AddPNode::Offset)));
1279 x->set_req(Address, adr_x);
1280 }
1281 }
1282 // Check for a 'win' on some paths
1283 const Type *t = x->Value(igvn);
1284
1285 bool singleton = t->singleton();
1286
1287 // See comments in PhaseIdealLoop::split_thru_phi().
1288 if (singleton && t == Type::TOP) {
1289 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1290 }
1291
1292 if (singleton) {
1293 x = igvn->makecon(t);
1294 } else {
1295 // We now call Identity to try to simplify the cloned node.
1296 // Note that some Identity methods call phase->type(this).
1297 // Make sure that the type array is big enough for
1298 // our new node, even though we may throw the node away.
1299 // (This tweaking with igvn only works because x is a new node.)
1300 igvn->set_type(x, t);
1301 // If x is a TypeNode, capture any more-precise type permanently into Node
1302 // otherwise it will be not updated during igvn->transform since
1303 // igvn->type(x) is set to x->Value() already.
1304 x->raise_bottom_type(t);
1305 Node *y = x->Identity(igvn);
1306 if (y != x) {
1307 x = y;
1308 } else {
1309 y = igvn->hash_find_insert(x);
1310 if (y) {
1311 x = y;
1312 } else {
1313 // Else x is a new node we are keeping
1314 // We do not need register_new_node_with_optimizer
1315 // because set_type has already been called.
1316 igvn->_worklist.push(x);
1317 }
1318 }
1319 }
1320 if (x != the_clone && the_clone != NULL) {
1321 igvn->remove_dead_node(the_clone);
1322 }
1323 phi->set_req(i, x);
1324 }
1325 // Record Phi
1326 igvn->register_new_node_with_optimizer(phi);
1327 return phi;
1328 }
1329
1330 //------------------------------Ideal------------------------------------------
1331 // If the load is from Field memory and the pointer is non-null, it might be possible to
1332 // zero out the control input.
1333 // If the offset is constant and the base is an object allocation,
1334 // try to hook me up to the exact initializing store.
1335 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1336 Node* p = MemNode::Ideal_common(phase, can_reshape);
1337 if (p) return (p == NodeSentinel) ? NULL : p;
1338
1339 Node* ctrl = in(MemNode::Control);
1340 Node* address = in(MemNode::Address);
1341
1342 // Skip up past a SafePoint control. Cannot do this for Stores because
1343 // pointer stores & cardmarks must stay on the same side of a SafePoint.
1344 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint &&
1345 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw ) {
1346 ctrl = ctrl->in(0);
1347 set_req(MemNode::Control,ctrl);
1348 }
1349
1350 intptr_t ignore = 0;
1351 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1352 if (base != NULL
1353 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
1354 // Check for useless control edge in some common special cases
1355 if (in(MemNode::Control) != NULL
1356 && can_remove_control()
1357 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1358 && all_controls_dominate(base, phase->C->start())) {
1359 // A method-invariant, non-null address (constant or 'this' argument).
1360 set_req(MemNode::Control, NULL);
1361 }
1362 }
1363
1364 Node* mem = in(MemNode::Memory);
1365 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1366
1367 if (can_reshape && (addr_t != NULL)) {
1368 // try to optimize our memory input
1369 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase);
1370 if (opt_mem != mem) {
1371 set_req(MemNode::Memory, opt_mem);
1372 if (phase->type( opt_mem ) == Type::TOP) return NULL;
1373 return this;
1374 }
1375 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1376 if ((t_oop != NULL) &&
1377 (t_oop->is_known_instance_field() ||
1378 t_oop->is_ptr_to_boxed_value())) {
1379 PhaseIterGVN *igvn = phase->is_IterGVN();
1380 if (igvn != NULL && igvn->_worklist.member(opt_mem)) {
1381 // Delay this transformation until memory Phi is processed.
1382 phase->is_IterGVN()->_worklist.push(this);
1383 return NULL;
1384 }
1385 // Split instance field load through Phi.
1386 Node* result = split_through_phi(phase);
1387 if (result != NULL) return result;
1388
1389 if (t_oop->is_ptr_to_boxed_value()) {
1390 Node* result = eliminate_autobox(phase);
1391 if (result != NULL) return result;
1392 }
1393 }
1394 }
1395
1396 // Check for prior store with a different base or offset; make Load
1397 // independent. Skip through any number of them. Bail out if the stores
1398 // are in an endless dead cycle and report no progress. This is a key
1399 // transform for Reflection. However, if after skipping through the Stores
1400 // we can't then fold up against a prior store do NOT do the transform as
1401 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
1402 // array memory alive twice: once for the hoisted Load and again after the
1403 // bypassed Store. This situation only works if EVERYBODY who does
1404 // anti-dependence work knows how to bypass. I.e. we need all
1405 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
1406 // the alias index stuff. So instead, peek through Stores and IFF we can
1407 // fold up, do so.
1408 Node* prev_mem = find_previous_store(phase);
1409 // Steps (a), (b): Walk past independent stores to find an exact match.
1410 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) {
1411 // (c) See if we can fold up on the spot, but don't fold up here.
1412 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
1413 // just return a prior value, which is done by Identity calls.
1414 if (can_see_stored_value(prev_mem, phase)) {
1415 // Make ready for step (d):
1416 set_req(MemNode::Memory, prev_mem);
1417 return this;
1418 }
1419 }
1420
1421 return NULL; // No further progress
1422 }
1423
1424 // Helper to recognize certain Klass fields which are invariant across
1425 // some group of array types (e.g., int[] or all T[] where T < Object).
1426 const Type*
1427 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1428 ciKlass* klass) const {
1429 if (tkls->offset() == in_bytes(Klass::modifier_flags_offset())) {
1430 // The field is Klass::_modifier_flags. Return its (constant) value.
1431 // (Folds up the 2nd indirection in aClassConstant.getModifiers().)
1432 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags");
1433 return TypeInt::make(klass->modifier_flags());
1434 }
1435 if (tkls->offset() == in_bytes(Klass::access_flags_offset())) {
1436 // The field is Klass::_access_flags. Return its (constant) value.
1437 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1438 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags");
1439 return TypeInt::make(klass->access_flags());
1440 }
1441 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) {
1442 // The field is Klass::_layout_helper. Return its constant value if known.
1443 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper");
1444 return TypeInt::make(klass->layout_helper());
1445 }
1446
1447 // No match.
1448 return NULL;
1449 }
1450
1451 // Try to constant-fold a stable array element.
1452 static const Type* fold_stable_ary_elem(const TypeAryPtr* ary, int off, BasicType loadbt) {
1453 assert(ary->const_oop(), "array should be constant");
1454 assert(ary->is_stable(), "array should be stable");
1455
1456 // Decode the results of GraphKit::array_element_address.
1457 ciArray* aobj = ary->const_oop()->as_array();
1458 ciConstant con = aobj->element_value_by_offset(off);
1459
1460 if (con.basic_type() != T_ILLEGAL && !con.is_null_or_zero()) {
1461 const Type* con_type = Type::make_from_constant(con);
1462 if (con_type != NULL) {
1463 if (con_type->isa_aryptr()) {
1464 // Join with the array element type, in case it is also stable.
1465 int dim = ary->stable_dimension();
1466 con_type = con_type->is_aryptr()->cast_to_stable(true, dim-1);
1467 }
1468 if (loadbt == T_NARROWOOP && con_type->isa_oopptr()) {
1469 con_type = con_type->make_narrowoop();
1470 }
1471 #ifndef PRODUCT
1472 if (TraceIterativeGVN) {
1473 tty->print("FoldStableValues: array element [off=%d]: con_type=", off);
1474 con_type->dump(); tty->cr();
1475 }
1476 #endif //PRODUCT
1477 return con_type;
1478 }
1479 }
1480 return NULL;
1481 }
1482
1483 //------------------------------Value-----------------------------------------
1484 const Type *LoadNode::Value( PhaseTransform *phase ) const {
1485 // Either input is TOP ==> the result is TOP
1486 Node* mem = in(MemNode::Memory);
1487 const Type *t1 = phase->type(mem);
1488 if (t1 == Type::TOP) return Type::TOP;
1489 Node* adr = in(MemNode::Address);
1490 const TypePtr* tp = phase->type(adr)->isa_ptr();
1491 if (tp == NULL || tp->empty()) return Type::TOP;
1492 int off = tp->offset();
1493 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
1494 Compile* C = phase->C;
1495
1496 // Try to guess loaded type from pointer type
1497 if (tp->isa_aryptr()) {
1498 const TypeAryPtr* ary = tp->is_aryptr();
1499 const Type* t = ary->elem();
1500
1501 // Determine whether the reference is beyond the header or not, by comparing
1502 // the offset against the offset of the start of the array's data.
1503 // Different array types begin at slightly different offsets (12 vs. 16).
1504 // We choose T_BYTE as an example base type that is least restrictive
1505 // as to alignment, which will therefore produce the smallest
1506 // possible base offset.
1507 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
1508 const bool off_beyond_header = (off != ShenandoahBrooksPointer::byte_offset() || !UseShenandoahGC) && ((uint)off >= (uint)min_base_off);
1509
1510 // Try to constant-fold a stable array element.
1511 if (FoldStableValues && ary->is_stable()) {
1512 // Make sure the reference is not into the header and the offset is constant
1513 ciObject* aobj = NULL;
1514 if (UseShenandoahGC && adr->is_AddP() && !adr->in(AddPNode::Base)->is_top()) {
1515 Node* base = ShenandoahBarrierNode::skip_through_barrier(adr->in(AddPNode::Base));
1516 if (!base->is_top()) {
1517 ary = phase->type(base)->is_aryptr();
1518 aobj = ary->const_oop();
1519 }
1520 } else {
1521 aobj = ary->const_oop();
1522 }
1523 if (aobj != NULL && off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) {
1524 const Type* con_type = fold_stable_ary_elem(ary, off, memory_type());
1525 if (con_type != NULL) {
1526 return con_type;
1527 }
1528 }
1529 }
1530
1531 // Don't do this for integer types. There is only potential profit if
1532 // the element type t is lower than _type; that is, for int types, if _type is
1533 // more restrictive than t. This only happens here if one is short and the other
1534 // char (both 16 bits), and in those cases we've made an intentional decision
1535 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
1536 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
1537 //
1538 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
1539 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
1540 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
1541 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
1542 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
1543 // In fact, that could have been the original type of p1, and p1 could have
1544 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
1545 // expression (LShiftL quux 3) independently optimized to the constant 8.
1546 if ((t->isa_int() == NULL) && (t->isa_long() == NULL)
1547 && (_type->isa_vect() == NULL)
1548 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
1549 // t might actually be lower than _type, if _type is a unique
1550 // concrete subclass of abstract class t.
1551 if (off_beyond_header) { // is the offset beyond the header?
1552 const Type* jt = t->join_speculative(_type);
1553 // In any case, do not allow the join, per se, to empty out the type.
1554 if (jt->empty() && !t->empty()) {
1555 // This can happen if a interface-typed array narrows to a class type.
1556 jt = _type;
1557 }
1558 #ifdef ASSERT
1559 if (phase->C->eliminate_boxing() && adr->is_AddP()) {
1560 // The pointers in the autobox arrays are always non-null
1561 Node* base = adr->in(AddPNode::Base);
1562 if ((base != NULL) && base->is_DecodeN()) {
1563 // Get LoadN node which loads IntegerCache.cache field
1564 base = base->in(1);
1565 }
1566 if ((base != NULL) && base->is_Con()) {
1567 const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr();
1568 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1569 // It could be narrow oop
1570 assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity");
1571 }
1572 }
1573 }
1574 #endif
1575 return jt;
1576 }
1577 }
1578 } else if (tp->base() == Type::InstPtr) {
1579 ciEnv* env = C->env();
1580 const TypeInstPtr* tinst = tp->is_instptr();
1581 ciKlass* klass = tinst->klass();
1582 assert( off != Type::OffsetBot ||
1583 // arrays can be cast to Objects
1584 tp->is_oopptr()->klass()->is_java_lang_Object() ||
1585 // unsafe field access may not have a constant offset
1586 C->has_unsafe_access(),
1587 "Field accesses must be precise" );
1588 // For oop loads, we expect the _type to be precise
1589 if (klass == env->String_klass() &&
1590 adr->is_AddP() && off != Type::OffsetBot) {
1591 // For constant Strings treat the final fields as compile time constants.
1592 Node* base = adr->in(AddPNode::Base);
1593 const TypeOopPtr* t = phase->type(base)->isa_oopptr();
1594 if (t != NULL && t->singleton()) {
1595 ciField* field = env->String_klass()->get_field_by_offset(off, false);
1596 if (field != NULL && field->is_final()) {
1597 ciObject* string = t->const_oop();
1598 ciConstant constant = string->as_instance()->field_value(field);
1599 if (constant.basic_type() == T_INT) {
1600 return TypeInt::make(constant.as_int());
1601 } else if (constant.basic_type() == T_ARRAY) {
1602 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
1603 return TypeNarrowOop::make_from_constant(constant.as_object(), true);
1604 } else {
1605 return TypeOopPtr::make_from_constant(constant.as_object(), true);
1606 }
1607 }
1608 }
1609 }
1610 }
1611 // Optimizations for constant objects
1612 ciObject* const_oop = NULL;
1613 if (UseShenandoahGC && adr->is_AddP() && !adr->in(AddPNode::Base)->is_top()) {
1614 Node* base = ShenandoahBarrierNode::skip_through_barrier(adr->in(AddPNode::Base));
1615 if (phase->type(base) != Type::TOP) {
1616 const TypePtr* base_t = phase->type(base)->is_ptr();
1617 if (base_t != TypePtr::NULL_PTR) {
1618 tinst = base_t->is_instptr();
1619 const_oop = tinst->const_oop();
1620 }
1621 }
1622 } else {
1623 const_oop = tinst->const_oop();
1624 }
1625 if (const_oop != NULL) {
1626 // For constant Boxed value treat the target field as a compile time constant.
1627 if (tinst->is_ptr_to_boxed_value()) {
1628 return tinst->get_const_boxed_value();
1629 } else
1630 // For constant CallSites treat the target field as a compile time constant.
1631 if (const_oop->is_call_site()) {
1632 ciCallSite* call_site = const_oop->as_call_site();
1633 ciField* field = call_site->klass()->as_instance_klass()->get_field_by_offset(off, /*is_static=*/ false);
1634 if (field != NULL && field->is_call_site_target()) {
1635 ciMethodHandle* target = call_site->get_target();
1636 if (target != NULL) { // just in case
1637 ciConstant constant(T_OBJECT, target);
1638 const Type* t;
1639 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
1640 t = TypeNarrowOop::make_from_constant(constant.as_object(), true);
1641 } else {
1642 t = TypeOopPtr::make_from_constant(constant.as_object(), true);
1643 }
1644 // Add a dependence for invalidation of the optimization.
1645 if (!call_site->is_constant_call_site()) {
1646 C->dependencies()->assert_call_site_target_value(call_site, target);
1647 }
1648 return t;
1649 }
1650 }
1651 }
1652 }
1653 } else if (tp->base() == Type::KlassPtr) {
1654 assert( off != Type::OffsetBot ||
1655 // arrays can be cast to Objects
1656 tp->is_klassptr()->klass()->is_java_lang_Object() ||
1657 // also allow array-loading from the primary supertype
1658 // array during subtype checks
1659 Opcode() == Op_LoadKlass,
1660 "Field accesses must be precise" );
1661 // For klass/static loads, we expect the _type to be precise
1662 }
1663
1664 const TypeKlassPtr *tkls = tp->isa_klassptr();
1665 if (tkls != NULL && !StressReflectiveCode) {
1666 ciKlass* klass = tkls->klass();
1667 if (klass->is_loaded() && tkls->klass_is_exact()) {
1668 // We are loading a field from a Klass metaobject whose identity
1669 // is known at compile time (the type is "exact" or "precise").
1670 // Check for fields we know are maintained as constants by the VM.
1671 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) {
1672 // The field is Klass::_super_check_offset. Return its (constant) value.
1673 // (Folds up type checking code.)
1674 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
1675 return TypeInt::make(klass->super_check_offset());
1676 }
1677 // Compute index into primary_supers array
1678 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1679 // Check for overflowing; use unsigned compare to handle the negative case.
1680 if( depth < ciKlass::primary_super_limit() ) {
1681 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1682 // (Folds up type checking code.)
1683 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1684 ciKlass *ss = klass->super_of_depth(depth);
1685 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1686 }
1687 const Type* aift = load_array_final_field(tkls, klass);
1688 if (aift != NULL) return aift;
1689 if (tkls->offset() == in_bytes(ArrayKlass::component_mirror_offset())
1690 && klass->is_array_klass()) {
1691 // The field is ArrayKlass::_component_mirror. Return its (constant) value.
1692 // (Folds up aClassConstant.getComponentType, common in Arrays.copyOf.)
1693 assert(Opcode() == Op_LoadP, "must load an oop from _component_mirror");
1694 return TypeInstPtr::make(klass->as_array_klass()->component_mirror());
1695 }
1696 if (tkls->offset() == in_bytes(Klass::java_mirror_offset())) {
1697 // The field is Klass::_java_mirror. Return its (constant) value.
1698 // (Folds up the 2nd indirection in anObjConstant.getClass().)
1699 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
1700 return TypeInstPtr::make(klass->java_mirror());
1701 }
1702 }
1703
1704 // We can still check if we are loading from the primary_supers array at a
1705 // shallow enough depth. Even though the klass is not exact, entries less
1706 // than or equal to its super depth are correct.
1707 if (klass->is_loaded() ) {
1708 ciType *inner = klass;
1709 while( inner->is_obj_array_klass() )
1710 inner = inner->as_obj_array_klass()->base_element_type();
1711 if( inner->is_instance_klass() &&
1712 !inner->as_instance_klass()->flags().is_interface() ) {
1713 // Compute index into primary_supers array
1714 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1715 // Check for overflowing; use unsigned compare to handle the negative case.
1716 if( depth < ciKlass::primary_super_limit() &&
1717 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case
1718 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1719 // (Folds up type checking code.)
1720 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1721 ciKlass *ss = klass->super_of_depth(depth);
1722 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1723 }
1724 }
1725 }
1726
1727 // If the type is enough to determine that the thing is not an array,
1728 // we can give the layout_helper a positive interval type.
1729 // This will help short-circuit some reflective code.
1730 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())
1731 && !klass->is_array_klass() // not directly typed as an array
1732 && !klass->is_interface() // specifically not Serializable & Cloneable
1733 && !klass->is_java_lang_Object() // not the supertype of all T[]
1734 ) {
1735 // Note: When interfaces are reliable, we can narrow the interface
1736 // test to (klass != Serializable && klass != Cloneable).
1737 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
1738 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
1739 // The key property of this type is that it folds up tests
1740 // for array-ness, since it proves that the layout_helper is positive.
1741 // Thus, a generic value like the basic object layout helper works fine.
1742 return TypeInt::make(min_size, max_jint, Type::WidenMin);
1743 }
1744 }
1745
1746 // If we are loading from a freshly-allocated object, produce a zero,
1747 // if the load is provably beyond the header of the object.
1748 // (Also allow a variable load from a fresh array to produce zero.)
1749 const TypeOopPtr *tinst = tp->isa_oopptr();
1750 bool is_instance = (tinst != NULL) && tinst->is_known_instance_field();
1751 bool is_boxed_value = (tinst != NULL) && tinst->is_ptr_to_boxed_value();
1752 if (ReduceFieldZeroing || is_instance || is_boxed_value) {
1753 Node* value = can_see_stored_value(mem,phase);
1754 if (value != NULL && value->is_Con()) {
1755 assert(value->bottom_type()->higher_equal(_type),"sanity");
1756 return value->bottom_type();
1757 }
1758 }
1759
1760 if (is_instance) {
1761 // If we have an instance type and our memory input is the
1762 // programs's initial memory state, there is no matching store,
1763 // so just return a zero of the appropriate type
1764 Node *mem = in(MemNode::Memory);
1765 if (mem->is_Parm() && mem->in(0)->is_Start()) {
1766 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
1767 return Type::get_zero_type(_type->basic_type());
1768 }
1769 }
1770 return _type;
1771 }
1772
1773 //------------------------------match_edge-------------------------------------
1774 // Do we Match on this edge index or not? Match only the address.
1775 uint LoadNode::match_edge(uint idx) const {
1776 return idx == MemNode::Address;
1777 }
1778
1779 //--------------------------LoadBNode::Ideal--------------------------------------
1780 //
1781 // If the previous store is to the same address as this load,
1782 // and the value stored was larger than a byte, replace this load
1783 // with the value stored truncated to a byte. If no truncation is
1784 // needed, the replacement is done in LoadNode::Identity().
1785 //
1786 Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1787 Node* mem = in(MemNode::Memory);
1788 Node* value = can_see_stored_value(mem,phase);
1789 if( value && !phase->type(value)->higher_equal( _type ) ) {
1790 Node *result = phase->transform( new (phase->C) LShiftINode(value, phase->intcon(24)) );
1791 return new (phase->C) RShiftINode(result, phase->intcon(24));
1792 }
1793 // Identity call will handle the case where truncation is not needed.
1794 return LoadNode::Ideal(phase, can_reshape);
1795 }
1796
1797 const Type* LoadBNode::Value(PhaseTransform *phase) const {
1798 Node* mem = in(MemNode::Memory);
1799 Node* value = can_see_stored_value(mem,phase);
1800 if (value != NULL && value->is_Con() &&
1801 !value->bottom_type()->higher_equal(_type)) {
1802 // If the input to the store does not fit with the load's result type,
1803 // it must be truncated. We can't delay until Ideal call since
1804 // a singleton Value is needed for split_thru_phi optimization.
1805 int con = value->get_int();
1806 return TypeInt::make((con << 24) >> 24);
1807 }
1808 return LoadNode::Value(phase);
1809 }
1810
1811 //--------------------------LoadUBNode::Ideal-------------------------------------
1812 //
1813 // If the previous store is to the same address as this load,
1814 // and the value stored was larger than a byte, replace this load
1815 // with the value stored truncated to a byte. If no truncation is
1816 // needed, the replacement is done in LoadNode::Identity().
1817 //
1818 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
1819 Node* mem = in(MemNode::Memory);
1820 Node* value = can_see_stored_value(mem, phase);
1821 if (value && !phase->type(value)->higher_equal(_type))
1822 return new (phase->C) AndINode(value, phase->intcon(0xFF));
1823 // Identity call will handle the case where truncation is not needed.
1824 return LoadNode::Ideal(phase, can_reshape);
1825 }
1826
1827 const Type* LoadUBNode::Value(PhaseTransform *phase) const {
1828 Node* mem = in(MemNode::Memory);
1829 Node* value = can_see_stored_value(mem,phase);
1830 if (value != NULL && value->is_Con() &&
1831 !value->bottom_type()->higher_equal(_type)) {
1832 // If the input to the store does not fit with the load's result type,
1833 // it must be truncated. We can't delay until Ideal call since
1834 // a singleton Value is needed for split_thru_phi optimization.
1835 int con = value->get_int();
1836 return TypeInt::make(con & 0xFF);
1837 }
1838 return LoadNode::Value(phase);
1839 }
1840
1841 //--------------------------LoadUSNode::Ideal-------------------------------------
1842 //
1843 // If the previous store is to the same address as this load,
1844 // and the value stored was larger than a char, replace this load
1845 // with the value stored truncated to a char. If no truncation is
1846 // needed, the replacement is done in LoadNode::Identity().
1847 //
1848 Node *LoadUSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1849 Node* mem = in(MemNode::Memory);
1850 Node* value = can_see_stored_value(mem,phase);
1851 if( value && !phase->type(value)->higher_equal( _type ) )
1852 return new (phase->C) AndINode(value,phase->intcon(0xFFFF));
1853 // Identity call will handle the case where truncation is not needed.
1854 return LoadNode::Ideal(phase, can_reshape);
1855 }
1856
1857 const Type* LoadUSNode::Value(PhaseTransform *phase) const {
1858 Node* mem = in(MemNode::Memory);
1859 Node* value = can_see_stored_value(mem,phase);
1860 if (value != NULL && value->is_Con() &&
1861 !value->bottom_type()->higher_equal(_type)) {
1862 // If the input to the store does not fit with the load's result type,
1863 // it must be truncated. We can't delay until Ideal call since
1864 // a singleton Value is needed for split_thru_phi optimization.
1865 int con = value->get_int();
1866 return TypeInt::make(con & 0xFFFF);
1867 }
1868 return LoadNode::Value(phase);
1869 }
1870
1871 //--------------------------LoadSNode::Ideal--------------------------------------
1872 //
1873 // If the previous store is to the same address as this load,
1874 // and the value stored was larger than a short, replace this load
1875 // with the value stored truncated to a short. If no truncation is
1876 // needed, the replacement is done in LoadNode::Identity().
1877 //
1878 Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1879 Node* mem = in(MemNode::Memory);
1880 Node* value = can_see_stored_value(mem,phase);
1881 if( value && !phase->type(value)->higher_equal( _type ) ) {
1882 Node *result = phase->transform( new (phase->C) LShiftINode(value, phase->intcon(16)) );
1883 return new (phase->C) RShiftINode(result, phase->intcon(16));
1884 }
1885 // Identity call will handle the case where truncation is not needed.
1886 return LoadNode::Ideal(phase, can_reshape);
1887 }
1888
1889 const Type* LoadSNode::Value(PhaseTransform *phase) const {
1890 Node* mem = in(MemNode::Memory);
1891 Node* value = can_see_stored_value(mem,phase);
1892 if (value != NULL && value->is_Con() &&
1893 !value->bottom_type()->higher_equal(_type)) {
1894 // If the input to the store does not fit with the load's result type,
1895 // it must be truncated. We can't delay until Ideal call since
1896 // a singleton Value is needed for split_thru_phi optimization.
1897 int con = value->get_int();
1898 return TypeInt::make((con << 16) >> 16);
1899 }
1900 return LoadNode::Value(phase);
1901 }
1902
1903 //=============================================================================
1904 //----------------------------LoadKlassNode::make------------------------------
1905 // Polymorphic factory method:
1906 Node* LoadKlassNode::make(PhaseGVN& gvn, Node* ctl, Node *mem, Node *adr, const TypePtr* at, const TypeKlassPtr *tk) {
1907 Compile* C = gvn.C;
1908 // sanity check the alias category against the created node type
1909 const TypePtr *adr_type = adr->bottom_type()->isa_ptr();
1910 assert(adr_type != NULL, "expecting TypeKlassPtr");
1911 #ifdef _LP64
1912 if (adr_type->is_ptr_to_narrowklass()) {
1913 assert(UseCompressedClassPointers, "no compressed klasses");
1914 Node* load_klass = gvn.transform(new (C) LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowklass(), MemNode::unordered));
1915 return new (C) DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr());
1916 }
1917 #endif
1918 assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
1919 return new (C) LoadKlassNode(ctl, mem, adr, at, tk, MemNode::unordered);
1920 }
1921
1922 //------------------------------Value------------------------------------------
1923 const Type *LoadKlassNode::Value( PhaseTransform *phase ) const {
1924 return klass_value_common(phase);
1925 }
1926
1927 // In most cases, LoadKlassNode does not have the control input set. If the control
1928 // input is set, it must not be removed (by LoadNode::Ideal()).
1929 bool LoadKlassNode::can_remove_control() const {
1930 return false;
1931 }
1932
1933 const Type *LoadNode::klass_value_common( PhaseTransform *phase ) const {
1934 // Either input is TOP ==> the result is TOP
1935 const Type *t1 = phase->type( in(MemNode::Memory) );
1936 if (t1 == Type::TOP) return Type::TOP;
1937 Node *adr = in(MemNode::Address);
1938 const Type *t2 = phase->type( adr );
1939 if (t2 == Type::TOP) return Type::TOP;
1940 const TypePtr *tp = t2->is_ptr();
1941 if (TypePtr::above_centerline(tp->ptr()) ||
1942 tp->ptr() == TypePtr::Null) return Type::TOP;
1943
1944 // Return a more precise klass, if possible
1945 const TypeInstPtr *tinst = tp->isa_instptr();
1946 if (tinst != NULL) {
1947 ciInstanceKlass* ik = tinst->klass()->as_instance_klass();
1948 int offset = tinst->offset();
1949 if (ik == phase->C->env()->Class_klass()
1950 && (offset == java_lang_Class::klass_offset_in_bytes() ||
1951 offset == java_lang_Class::array_klass_offset_in_bytes())) {
1952 // We are loading a special hidden field from a Class mirror object,
1953 // the field which points to the VM's Klass metaobject.
1954 ciType* t = tinst->java_mirror_type();
1955 // java_mirror_type returns non-null for compile-time Class constants.
1956 if (t != NULL) {
1957 // constant oop => constant klass
1958 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
1959 if (t->is_void()) {
1960 // We cannot create a void array. Since void is a primitive type return null
1961 // klass. Users of this result need to do a null check on the returned klass.
1962 return TypePtr::NULL_PTR;
1963 }
1964 return TypeKlassPtr::make(ciArrayKlass::make(t));
1965 }
1966 if (!t->is_klass()) {
1967 // a primitive Class (e.g., int.class) has NULL for a klass field
1968 return TypePtr::NULL_PTR;
1969 }
1970 // (Folds up the 1st indirection in aClassConstant.getModifiers().)
1971 return TypeKlassPtr::make(t->as_klass());
1972 }
1973 // non-constant mirror, so we can't tell what's going on
1974 }
1975 if( !ik->is_loaded() )
1976 return _type; // Bail out if not loaded
1977 if (offset == oopDesc::klass_offset_in_bytes()) {
1978 if (tinst->klass_is_exact()) {
1979 return TypeKlassPtr::make(ik);
1980 }
1981 // See if we can become precise: no subklasses and no interface
1982 // (Note: We need to support verified interfaces.)
1983 if (!ik->is_interface() && !ik->has_subklass()) {
1984 //assert(!UseExactTypes, "this code should be useless with exact types");
1985 // Add a dependence; if any subclass added we need to recompile
1986 if (!ik->is_final()) {
1987 // %%% should use stronger assert_unique_concrete_subtype instead
1988 phase->C->dependencies()->assert_leaf_type(ik);
1989 }
1990 // Return precise klass
1991 return TypeKlassPtr::make(ik);
1992 }
1993
1994 // Return root of possible klass
1995 return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/);
1996 }
1997 }
1998
1999 // Check for loading klass from an array
2000 const TypeAryPtr *tary = tp->isa_aryptr();
2001 if( tary != NULL ) {
2002 ciKlass *tary_klass = tary->klass();
2003 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP
2004 && tary->offset() == oopDesc::klass_offset_in_bytes()) {
2005 if (tary->klass_is_exact()) {
2006 return TypeKlassPtr::make(tary_klass);
2007 }
2008 ciArrayKlass *ak = tary->klass()->as_array_klass();
2009 // If the klass is an object array, we defer the question to the
2010 // array component klass.
2011 if( ak->is_obj_array_klass() ) {
2012 assert( ak->is_loaded(), "" );
2013 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass();
2014 if( base_k->is_loaded() && base_k->is_instance_klass() ) {
2015 ciInstanceKlass* ik = base_k->as_instance_klass();
2016 // See if we can become precise: no subklasses and no interface
2017 if (!ik->is_interface() && !ik->has_subklass()) {
2018 //assert(!UseExactTypes, "this code should be useless with exact types");
2019 // Add a dependence; if any subclass added we need to recompile
2020 if (!ik->is_final()) {
2021 phase->C->dependencies()->assert_leaf_type(ik);
2022 }
2023 // Return precise array klass
2024 return TypeKlassPtr::make(ak);
2025 }
2026 }
2027 return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/);
2028 } else { // Found a type-array?
2029 //assert(!UseExactTypes, "this code should be useless with exact types");
2030 assert( ak->is_type_array_klass(), "" );
2031 return TypeKlassPtr::make(ak); // These are always precise
2032 }
2033 }
2034 }
2035
2036 // Check for loading klass from an array klass
2037 const TypeKlassPtr *tkls = tp->isa_klassptr();
2038 if (tkls != NULL && !StressReflectiveCode) {
2039 ciKlass* klass = tkls->klass();
2040 if( !klass->is_loaded() )
2041 return _type; // Bail out if not loaded
2042 if( klass->is_obj_array_klass() &&
2043 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) {
2044 ciKlass* elem = klass->as_obj_array_klass()->element_klass();
2045 // // Always returning precise element type is incorrect,
2046 // // e.g., element type could be object and array may contain strings
2047 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
2048
2049 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
2050 // according to the element type's subclassing.
2051 return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/);
2052 }
2053 if( klass->is_instance_klass() && tkls->klass_is_exact() &&
2054 tkls->offset() == in_bytes(Klass::super_offset())) {
2055 ciKlass* sup = klass->as_instance_klass()->super();
2056 // The field is Klass::_super. Return its (constant) value.
2057 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
2058 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR;
2059 }
2060 }
2061
2062 // Bailout case
2063 return LoadNode::Value(phase);
2064 }
2065
2066 //------------------------------Identity---------------------------------------
2067 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
2068 // Also feed through the klass in Allocate(...klass...)._klass.
2069 Node* LoadKlassNode::Identity( PhaseTransform *phase ) {
2070 return klass_identity_common(phase);
2071 }
2072
2073 Node* LoadNode::klass_identity_common(PhaseTransform *phase ) {
2074 Node* x = LoadNode::Identity(phase);
2075 if (x != this) return x;
2076
2077 // Take apart the address into an oop and and offset.
2078 // Return 'this' if we cannot.
2079 Node* adr = in(MemNode::Address);
2080 intptr_t offset = 0;
2081 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2082 if (base == NULL) return this;
2083 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
2084 if (toop == NULL) return this;
2085
2086 // We can fetch the klass directly through an AllocateNode.
2087 // This works even if the klass is not constant (clone or newArray).
2088 if (offset == oopDesc::klass_offset_in_bytes()) {
2089 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
2090 if (allocated_klass != NULL) {
2091 return allocated_klass;
2092 }
2093 }
2094
2095 // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*.
2096 // Simplify ak.component_mirror.array_klass to plain ak, ak an ArrayKlass.
2097 // See inline_native_Class_query for occurrences of these patterns.
2098 // Java Example: x.getClass().isAssignableFrom(y)
2099 // Java Example: Array.newInstance(x.getClass().getComponentType(), n)
2100 //
2101 // This improves reflective code, often making the Class
2102 // mirror go completely dead. (Current exception: Class
2103 // mirrors may appear in debug info, but we could clean them out by
2104 // introducing a new debug info operator for Klass*.java_mirror).
2105 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass()
2106 && (offset == java_lang_Class::klass_offset_in_bytes() ||
2107 offset == java_lang_Class::array_klass_offset_in_bytes())) {
2108 // We are loading a special hidden field from a Class mirror,
2109 // the field which points to its Klass or ArrayKlass metaobject.
2110 if (base->is_Load()) {
2111 Node* adr2 = base->in(MemNode::Address);
2112 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2113 if (tkls != NULL && !tkls->empty()
2114 && (tkls->klass()->is_instance_klass() ||
2115 tkls->klass()->is_array_klass())
2116 && adr2->is_AddP()
2117 ) {
2118 int mirror_field = in_bytes(Klass::java_mirror_offset());
2119 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
2120 mirror_field = in_bytes(ArrayKlass::component_mirror_offset());
2121 }
2122 if (tkls->offset() == mirror_field) {
2123 return adr2->in(AddPNode::Base);
2124 }
2125 }
2126 }
2127 }
2128
2129 return this;
2130 }
2131
2132
2133 //------------------------------Value------------------------------------------
2134 const Type *LoadNKlassNode::Value( PhaseTransform *phase ) const {
2135 const Type *t = klass_value_common(phase);
2136 if (t == Type::TOP)
2137 return t;
2138
2139 return t->make_narrowklass();
2140 }
2141
2142 //------------------------------Identity---------------------------------------
2143 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
2144 // Also feed through the klass in Allocate(...klass...)._klass.
2145 Node* LoadNKlassNode::Identity( PhaseTransform *phase ) {
2146 Node *x = klass_identity_common(phase);
2147
2148 const Type *t = phase->type( x );
2149 if( t == Type::TOP ) return x;
2150 if( t->isa_narrowklass()) return x;
2151 assert (!t->isa_narrowoop(), "no narrow oop here");
2152
2153 return phase->transform(new (phase->C) EncodePKlassNode(x, t->make_narrowklass()));
2154 }
2155
2156 //------------------------------Value-----------------------------------------
2157 const Type *LoadRangeNode::Value( PhaseTransform *phase ) const {
2158 // Either input is TOP ==> the result is TOP
2159 const Type *t1 = phase->type( in(MemNode::Memory) );
2160 if( t1 == Type::TOP ) return Type::TOP;
2161 Node *adr = in(MemNode::Address);
2162 const Type *t2 = phase->type( adr );
2163 if( t2 == Type::TOP ) return Type::TOP;
2164 const TypePtr *tp = t2->is_ptr();
2165 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
2166 const TypeAryPtr *tap = tp->isa_aryptr();
2167 if( !tap ) return _type;
2168 return tap->size();
2169 }
2170
2171 //-------------------------------Ideal---------------------------------------
2172 // Feed through the length in AllocateArray(...length...)._length.
2173 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2174 Node* p = MemNode::Ideal_common(phase, can_reshape);
2175 if (p) return (p == NodeSentinel) ? NULL : p;
2176
2177 // Take apart the address into an oop and and offset.
2178 // Return 'this' if we cannot.
2179 Node* adr = in(MemNode::Address);
2180 intptr_t offset = 0;
2181 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2182 if (base == NULL) return NULL;
2183 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2184 if (tary == NULL) return NULL;
2185
2186 // We can fetch the length directly through an AllocateArrayNode.
2187 // This works even if the length is not constant (clone or newArray).
2188 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2189 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2190 if (alloc != NULL) {
2191 Node* allocated_length = alloc->Ideal_length();
2192 Node* len = alloc->make_ideal_length(tary, phase);
2193 if (allocated_length != len) {
2194 // New CastII improves on this.
2195 return len;
2196 }
2197 }
2198 }
2199
2200 return NULL;
2201 }
2202
2203 //------------------------------Identity---------------------------------------
2204 // Feed through the length in AllocateArray(...length...)._length.
2205 Node* LoadRangeNode::Identity( PhaseTransform *phase ) {
2206 Node* x = LoadINode::Identity(phase);
2207 if (x != this) return x;
2208
2209 // Take apart the address into an oop and and offset.
2210 // Return 'this' if we cannot.
2211 Node* adr = in(MemNode::Address);
2212 intptr_t offset = 0;
2213 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2214 if (base == NULL) return this;
2215 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2216 if (tary == NULL) return this;
2217
2218 // We can fetch the length directly through an AllocateArrayNode.
2219 // This works even if the length is not constant (clone or newArray).
2220 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2221 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2222 if (alloc != NULL) {
2223 Node* allocated_length = alloc->Ideal_length();
2224 // Do not allow make_ideal_length to allocate a CastII node.
2225 Node* len = alloc->make_ideal_length(tary, phase, false);
2226 if (allocated_length == len) {
2227 // Return allocated_length only if it would not be improved by a CastII.
2228 return allocated_length;
2229 }
2230 }
2231 }
2232
2233 return this;
2234
2235 }
2236
2237 //=============================================================================
2238 //---------------------------StoreNode::make-----------------------------------
2239 // Polymorphic factory method:
2240 StoreNode* StoreNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt, MemOrd mo) {
2241 assert((mo == unordered || mo == release), "unexpected");
2242 Compile* C = gvn.C;
2243 assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2244 ctl != NULL, "raw memory operations should have control edge");
2245
2246 switch (bt) {
2247 case T_BOOLEAN: val = gvn.transform(new (C) AndINode(val, gvn.intcon(0x1))); // Fall through to T_BYTE case
2248 case T_BYTE: return new (C) StoreBNode(ctl, mem, adr, adr_type, val, mo);
2249 case T_INT: return new (C) StoreINode(ctl, mem, adr, adr_type, val, mo);
2250 case T_CHAR:
2251 case T_SHORT: return new (C) StoreCNode(ctl, mem, adr, adr_type, val, mo);
2252 case T_LONG: return new (C) StoreLNode(ctl, mem, adr, adr_type, val, mo);
2253 case T_FLOAT: return new (C) StoreFNode(ctl, mem, adr, adr_type, val, mo);
2254 case T_DOUBLE: return new (C) StoreDNode(ctl, mem, adr, adr_type, val, mo);
2255 case T_METADATA:
2256 case T_ADDRESS:
2257 case T_OBJECT:
2258 #ifdef _LP64
2259 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
2260 val = gvn.transform(new (C) EncodePNode(val, val->bottom_type()->make_narrowoop()));
2261 return new (C) StoreNNode(ctl, mem, adr, adr_type, val, mo);
2262 } else if (adr->bottom_type()->is_ptr_to_narrowklass() ||
2263 (UseCompressedClassPointers && val->bottom_type()->isa_klassptr() &&
2264 adr->bottom_type()->isa_rawptr())) {
2265 val = gvn.transform(new (C) EncodePKlassNode(val, val->bottom_type()->make_narrowklass()));
2266 return new (C) StoreNKlassNode(ctl, mem, adr, adr_type, val, mo);
2267 }
2268 #endif
2269 {
2270 return new (C) StorePNode(ctl, mem, adr, adr_type, val, mo);
2271 }
2272 }
2273 ShouldNotReachHere();
2274 return (StoreNode*)NULL;
2275 }
2276
2277 StoreLNode* StoreLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
2278 bool require_atomic = true;
2279 return new (C) StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
2280 }
2281
2282 StoreDNode* StoreDNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
2283 bool require_atomic = true;
2284 return new (C) StoreDNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
2285 }
2286
2287
2288 //--------------------------bottom_type----------------------------------------
2289 const Type *StoreNode::bottom_type() const {
2290 return Type::MEMORY;
2291 }
2292
2293 //------------------------------hash-------------------------------------------
2294 uint StoreNode::hash() const {
2295 // unroll addition of interesting fields
2296 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2297
2298 // Since they are not commoned, do not hash them:
2299 return NO_HASH;
2300 }
2301
2302 //------------------------------Ideal------------------------------------------
2303 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
2304 // When a store immediately follows a relevant allocation/initialization,
2305 // try to capture it into the initialization, or hoist it above.
2306 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2307 Node* p = MemNode::Ideal_common(phase, can_reshape);
2308 if (p) return (p == NodeSentinel) ? NULL : p;
2309
2310 Node* mem = in(MemNode::Memory);
2311 Node* address = in(MemNode::Address);
2312
2313 // Back-to-back stores to same address? Fold em up. Generally
2314 // unsafe if I have intervening uses... Also disallowed for StoreCM
2315 // since they must follow each StoreP operation. Redundant StoreCMs
2316 // are eliminated just before matching in final_graph_reshape.
2317 if (mem->is_Store() && mem->in(MemNode::Address)->eqv_uncast(address) &&
2318 mem->Opcode() != Op_StoreCM) {
2319 // Looking at a dead closed cycle of memory?
2320 assert(mem != mem->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
2321
2322 assert(Opcode() == mem->Opcode() ||
2323 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw,
2324 "no mismatched stores, except on raw memory");
2325
2326 if (mem->outcnt() == 1 && // check for intervening uses
2327 mem->as_Store()->memory_size() <= this->memory_size()) {
2328 // If anybody other than 'this' uses 'mem', we cannot fold 'mem' away.
2329 // For example, 'mem' might be the final state at a conditional return.
2330 // Or, 'mem' might be used by some node which is live at the same time
2331 // 'this' is live, which might be unschedulable. So, require exactly
2332 // ONE user, the 'this' store, until such time as we clone 'mem' for
2333 // each of 'mem's uses (thus making the exactly-1-user-rule hold true).
2334 if (can_reshape) { // (%%% is this an anachronism?)
2335 set_req_X(MemNode::Memory, mem->in(MemNode::Memory),
2336 phase->is_IterGVN());
2337 } else {
2338 // It's OK to do this in the parser, since DU info is always accurate,
2339 // and the parser always refers to nodes via SafePointNode maps.
2340 set_req(MemNode::Memory, mem->in(MemNode::Memory));
2341 }
2342 return this;
2343 }
2344 }
2345
2346 // Capture an unaliased, unconditional, simple store into an initializer.
2347 // Or, if it is independent of the allocation, hoist it above the allocation.
2348 if (ReduceFieldZeroing && /*can_reshape &&*/
2349 mem->is_Proj() && mem->in(0)->is_Initialize()) {
2350 InitializeNode* init = mem->in(0)->as_Initialize();
2351 intptr_t offset = init->can_capture_store(this, phase, can_reshape);
2352 if (offset > 0) {
2353 Node* moved = init->capture_store(this, offset, phase, can_reshape);
2354 // If the InitializeNode captured me, it made a raw copy of me,
2355 // and I need to disappear.
2356 if (moved != NULL) {
2357 // %%% hack to ensure that Ideal returns a new node:
2358 mem = MergeMemNode::make(phase->C, mem);
2359 return mem; // fold me away
2360 }
2361 }
2362 }
2363
2364 return NULL; // No further progress
2365 }
2366
2367 //------------------------------Value-----------------------------------------
2368 const Type *StoreNode::Value( PhaseTransform *phase ) const {
2369 // Either input is TOP ==> the result is TOP
2370 const Type *t1 = phase->type( in(MemNode::Memory) );
2371 if( t1 == Type::TOP ) return Type::TOP;
2372 const Type *t2 = phase->type( in(MemNode::Address) );
2373 if( t2 == Type::TOP ) return Type::TOP;
2374 const Type *t3 = phase->type( in(MemNode::ValueIn) );
2375 if( t3 == Type::TOP ) return Type::TOP;
2376 return Type::MEMORY;
2377 }
2378
2379 //------------------------------Identity---------------------------------------
2380 // Remove redundant stores:
2381 // Store(m, p, Load(m, p)) changes to m.
2382 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
2383 Node *StoreNode::Identity( PhaseTransform *phase ) {
2384 Node* mem = in(MemNode::Memory);
2385 Node* adr = in(MemNode::Address);
2386 Node* val = in(MemNode::ValueIn);
2387
2388 // Load then Store? Then the Store is useless
2389 if (val->is_Load() &&
2390 val->in(MemNode::Address)->eqv_uncast(adr) &&
2391 val->in(MemNode::Memory )->eqv_uncast(mem) &&
2392 val->as_Load()->store_Opcode() == Opcode()) {
2393 return mem;
2394 }
2395
2396 // Two stores in a row of the same value?
2397 if (mem->is_Store() &&
2398 mem->in(MemNode::Address)->eqv_uncast(adr) &&
2399 mem->in(MemNode::ValueIn)->eqv_uncast(val) &&
2400 mem->Opcode() == Opcode()) {
2401 return mem;
2402 }
2403
2404 // Store of zero anywhere into a freshly-allocated object?
2405 // Then the store is useless.
2406 // (It must already have been captured by the InitializeNode.)
2407 if (ReduceFieldZeroing && phase->type(val)->is_zero_type()) {
2408 // a newly allocated object is already all-zeroes everywhere
2409 if (mem->is_Proj() && mem->in(0)->is_Allocate()) {
2410 return mem;
2411 }
2412
2413 // the store may also apply to zero-bits in an earlier object
2414 Node* prev_mem = find_previous_store(phase);
2415 // Steps (a), (b): Walk past independent stores to find an exact match.
2416 if (prev_mem != NULL) {
2417 Node* prev_val = can_see_stored_value(prev_mem, phase);
2418 if (prev_val != NULL && phase->eqv(prev_val, val)) {
2419 // prev_val and val might differ by a cast; it would be good
2420 // to keep the more informative of the two.
2421 return mem;
2422 }
2423 }
2424 }
2425
2426 return this;
2427 }
2428
2429 //------------------------------match_edge-------------------------------------
2430 // Do we Match on this edge index or not? Match only memory & value
2431 uint StoreNode::match_edge(uint idx) const {
2432 return idx == MemNode::Address || idx == MemNode::ValueIn;
2433 }
2434
2435 //------------------------------cmp--------------------------------------------
2436 // Do not common stores up together. They generally have to be split
2437 // back up anyways, so do not bother.
2438 uint StoreNode::cmp( const Node &n ) const {
2439 return (&n == this); // Always fail except on self
2440 }
2441
2442 //------------------------------Ideal_masked_input-----------------------------
2443 // Check for a useless mask before a partial-word store
2444 // (StoreB ... (AndI valIn conIa) )
2445 // If (conIa & mask == mask) this simplifies to
2446 // (StoreB ... (valIn) )
2447 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
2448 Node *val = in(MemNode::ValueIn);
2449 if( val->Opcode() == Op_AndI ) {
2450 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2451 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
2452 set_req(MemNode::ValueIn, val->in(1));
2453 return this;
2454 }
2455 }
2456 return NULL;
2457 }
2458
2459
2460 //------------------------------Ideal_sign_extended_input----------------------
2461 // Check for useless sign-extension before a partial-word store
2462 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) )
2463 // If (conIL == conIR && conIR <= num_bits) this simplifies to
2464 // (StoreB ... (valIn) )
2465 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) {
2466 Node *val = in(MemNode::ValueIn);
2467 if( val->Opcode() == Op_RShiftI ) {
2468 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2469 if( t && t->is_con() && (t->get_con() <= num_bits) ) {
2470 Node *shl = val->in(1);
2471 if( shl->Opcode() == Op_LShiftI ) {
2472 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int();
2473 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) {
2474 set_req(MemNode::ValueIn, shl->in(1));
2475 return this;
2476 }
2477 }
2478 }
2479 }
2480 return NULL;
2481 }
2482
2483 //------------------------------value_never_loaded-----------------------------------
2484 // Determine whether there are any possible loads of the value stored.
2485 // For simplicity, we actually check if there are any loads from the
2486 // address stored to, not just for loads of the value stored by this node.
2487 //
2488 bool StoreNode::value_never_loaded( PhaseTransform *phase) const {
2489 Node *adr = in(Address);
2490 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
2491 if (adr_oop == NULL)
2492 return false;
2493 if (!adr_oop->is_known_instance_field())
2494 return false; // if not a distinct instance, there may be aliases of the address
2495 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
2496 Node *use = adr->fast_out(i);
2497 int opc = use->Opcode();
2498 if (use->is_Load() || use->is_LoadStore()) {
2499 return false;
2500 }
2501 }
2502 return true;
2503 }
2504
2505 //=============================================================================
2506 //------------------------------Ideal------------------------------------------
2507 // If the store is from an AND mask that leaves the low bits untouched, then
2508 // we can skip the AND operation. If the store is from a sign-extension
2509 // (a left shift, then right shift) we can skip both.
2510 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
2511 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
2512 if( progress != NULL ) return progress;
2513
2514 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
2515 if( progress != NULL ) return progress;
2516
2517 // Finally check the default case
2518 return StoreNode::Ideal(phase, can_reshape);
2519 }
2520
2521 //=============================================================================
2522 //------------------------------Ideal------------------------------------------
2523 // If the store is from an AND mask that leaves the low bits untouched, then
2524 // we can skip the AND operation
2525 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
2526 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
2527 if( progress != NULL ) return progress;
2528
2529 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
2530 if( progress != NULL ) return progress;
2531
2532 // Finally check the default case
2533 return StoreNode::Ideal(phase, can_reshape);
2534 }
2535
2536 //=============================================================================
2537 //------------------------------Identity---------------------------------------
2538 Node *StoreCMNode::Identity( PhaseTransform *phase ) {
2539 // No need to card mark when storing a null ptr
2540 Node* my_store = in(MemNode::OopStore);
2541 if (my_store->is_Store()) {
2542 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) );
2543 if( t1 == TypePtr::NULL_PTR ) {
2544 return in(MemNode::Memory);
2545 }
2546 }
2547 return this;
2548 }
2549
2550 //=============================================================================
2551 //------------------------------Ideal---------------------------------------
2552 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){
2553 Node* progress = StoreNode::Ideal(phase, can_reshape);
2554 if (progress != NULL) return progress;
2555
2556 Node* my_store = in(MemNode::OopStore);
2557 if (my_store->is_MergeMem()) {
2558 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx());
2559 set_req(MemNode::OopStore, mem);
2560 return this;
2561 }
2562
2563 return NULL;
2564 }
2565
2566 //------------------------------Value-----------------------------------------
2567 const Type *StoreCMNode::Value( PhaseTransform *phase ) const {
2568 // Either input is TOP ==> the result is TOP
2569 const Type *t = phase->type( in(MemNode::Memory) );
2570 if( t == Type::TOP ) return Type::TOP;
2571 t = phase->type( in(MemNode::Address) );
2572 if( t == Type::TOP ) return Type::TOP;
2573 t = phase->type( in(MemNode::ValueIn) );
2574 if( t == Type::TOP ) return Type::TOP;
2575 // If extra input is TOP ==> the result is TOP
2576 t = phase->type( in(MemNode::OopStore) );
2577 if( t == Type::TOP ) return Type::TOP;
2578
2579 return StoreNode::Value( phase );
2580 }
2581
2582
2583 //=============================================================================
2584 //----------------------------------SCMemProjNode------------------------------
2585 const Type * SCMemProjNode::Value( PhaseTransform *phase ) const
2586 {
2587 return bottom_type();
2588 }
2589
2590 //=============================================================================
2591 //----------------------------------LoadStoreNode------------------------------
2592 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required )
2593 : Node(required),
2594 _type(rt),
2595 _adr_type(at)
2596 {
2597 init_req(MemNode::Control, c );
2598 init_req(MemNode::Memory , mem);
2599 init_req(MemNode::Address, adr);
2600 init_req(MemNode::ValueIn, val);
2601 init_class_id(Class_LoadStore);
2602 }
2603
2604 uint LoadStoreNode::ideal_reg() const {
2605 return _type->ideal_reg();
2606 }
2607
2608 bool LoadStoreNode::result_not_used() const {
2609 for( DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++ ) {
2610 Node *x = fast_out(i);
2611 if (x->Opcode() == Op_SCMemProj) continue;
2612 return false;
2613 }
2614 return true;
2615 }
2616
2617 uint LoadStoreNode::size_of() const { return sizeof(*this); }
2618
2619 //=============================================================================
2620 //----------------------------------LoadStoreConditionalNode--------------------
2621 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, NULL, TypeInt::BOOL, 5) {
2622 init_req(ExpectedIn, ex );
2623 }
2624
2625 //=============================================================================
2626 //-------------------------------adr_type--------------------------------------
2627 // Do we Match on this edge index or not? Do not match memory
2628 const TypePtr* ClearArrayNode::adr_type() const {
2629 Node *adr = in(3);
2630 return MemNode::calculate_adr_type(adr->bottom_type());
2631 }
2632
2633 //------------------------------match_edge-------------------------------------
2634 // Do we Match on this edge index or not? Do not match memory
2635 uint ClearArrayNode::match_edge(uint idx) const {
2636 return idx > 1;
2637 }
2638
2639 //------------------------------Identity---------------------------------------
2640 // Clearing a zero length array does nothing
2641 Node *ClearArrayNode::Identity( PhaseTransform *phase ) {
2642 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
2643 }
2644
2645 //------------------------------Idealize---------------------------------------
2646 // Clearing a short array is faster with stores
2647 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape){
2648 const int unit = BytesPerLong;
2649 const TypeX* t = phase->type(in(2))->isa_intptr_t();
2650 if (!t) return NULL;
2651 if (!t->is_con()) return NULL;
2652 intptr_t raw_count = t->get_con();
2653 intptr_t size = raw_count;
2654 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
2655 // Clearing nothing uses the Identity call.
2656 // Negative clears are possible on dead ClearArrays
2657 // (see jck test stmt114.stmt11402.val).
2658 if (size <= 0 || size % unit != 0) return NULL;
2659 intptr_t count = size / unit;
2660 // Length too long; use fast hardware clear
2661 if (size > Matcher::init_array_short_size) return NULL;
2662 Node *mem = in(1);
2663 if( phase->type(mem)==Type::TOP ) return NULL;
2664 Node *adr = in(3);
2665 const Type* at = phase->type(adr);
2666 if( at==Type::TOP ) return NULL;
2667 const TypePtr* atp = at->isa_ptr();
2668 // adjust atp to be the correct array element address type
2669 if (atp == NULL) atp = TypePtr::BOTTOM;
2670 else atp = atp->add_offset(Type::OffsetBot);
2671 // Get base for derived pointer purposes
2672 if( adr->Opcode() != Op_AddP ) Unimplemented();
2673 Node *base = adr->in(1);
2674
2675 Node *zero = phase->makecon(TypeLong::ZERO);
2676 Node *off = phase->MakeConX(BytesPerLong);
2677 mem = new (phase->C) StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
2678 count--;
2679 while( count-- ) {
2680 mem = phase->transform(mem);
2681 adr = phase->transform(new (phase->C) AddPNode(base,adr,off));
2682 mem = new (phase->C) StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
2683 }
2684 return mem;
2685 }
2686
2687 //----------------------------step_through----------------------------------
2688 // Return allocation input memory edge if it is different instance
2689 // or itself if it is the one we are looking for.
2690 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) {
2691 Node* n = *np;
2692 assert(n->is_ClearArray(), "sanity");
2693 intptr_t offset;
2694 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
2695 // This method is called only before Allocate nodes are expanded during
2696 // macro nodes expansion. Before that ClearArray nodes are only generated
2697 // in LibraryCallKit::generate_arraycopy() which follows allocations.
2698 assert(alloc != NULL, "should have allocation");
2699 if (alloc->_idx == instance_id) {
2700 // Can not bypass initialization of the instance we are looking for.
2701 return false;
2702 }
2703 // Otherwise skip it.
2704 InitializeNode* init = alloc->initialization();
2705 if (init != NULL)
2706 *np = init->in(TypeFunc::Memory);
2707 else
2708 *np = alloc->in(TypeFunc::Memory);
2709 return true;
2710 }
2711
2712 //----------------------------clear_memory-------------------------------------
2713 // Generate code to initialize object storage to zero.
2714 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2715 intptr_t start_offset,
2716 Node* end_offset,
2717 PhaseGVN* phase) {
2718 Compile* C = phase->C;
2719 intptr_t offset = start_offset;
2720
2721 int unit = BytesPerLong;
2722 if ((offset % unit) != 0) {
2723 Node* adr = new (C) AddPNode(dest, dest, phase->MakeConX(offset));
2724 adr = phase->transform(adr);
2725 const TypePtr* atp = TypeRawPtr::BOTTOM;
2726 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
2727 mem = phase->transform(mem);
2728 offset += BytesPerInt;
2729 }
2730 assert((offset % unit) == 0, "");
2731
2732 // Initialize the remaining stuff, if any, with a ClearArray.
2733 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase);
2734 }
2735
2736 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2737 Node* start_offset,
2738 Node* end_offset,
2739 PhaseGVN* phase) {
2740 if (start_offset == end_offset) {
2741 // nothing to do
2742 return mem;
2743 }
2744
2745 Compile* C = phase->C;
2746 int unit = BytesPerLong;
2747 Node* zbase = start_offset;
2748 Node* zend = end_offset;
2749
2750 // Scale to the unit required by the CPU:
2751 if (!Matcher::init_array_count_is_in_bytes) {
2752 Node* shift = phase->intcon(exact_log2(unit));
2753 zbase = phase->transform( new(C) URShiftXNode(zbase, shift) );
2754 zend = phase->transform( new(C) URShiftXNode(zend, shift) );
2755 }
2756
2757 // Bulk clear double-words
2758 Node* zsize = phase->transform( new(C) SubXNode(zend, zbase) );
2759 Node* adr = phase->transform( new(C) AddPNode(dest, dest, start_offset) );
2760 mem = new (C) ClearArrayNode(ctl, mem, zsize, adr);
2761 return phase->transform(mem);
2762 }
2763
2764 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2765 intptr_t start_offset,
2766 intptr_t end_offset,
2767 PhaseGVN* phase) {
2768 if (start_offset == end_offset) {
2769 // nothing to do
2770 return mem;
2771 }
2772
2773 Compile* C = phase->C;
2774 assert((end_offset % BytesPerInt) == 0, "odd end offset");
2775 intptr_t done_offset = end_offset;
2776 if ((done_offset % BytesPerLong) != 0) {
2777 done_offset -= BytesPerInt;
2778 }
2779 if (done_offset > start_offset) {
2780 mem = clear_memory(ctl, mem, dest,
2781 start_offset, phase->MakeConX(done_offset), phase);
2782 }
2783 if (done_offset < end_offset) { // emit the final 32-bit store
2784 Node* adr = new (C) AddPNode(dest, dest, phase->MakeConX(done_offset));
2785 adr = phase->transform(adr);
2786 const TypePtr* atp = TypeRawPtr::BOTTOM;
2787 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
2788 mem = phase->transform(mem);
2789 done_offset += BytesPerInt;
2790 }
2791 assert(done_offset == end_offset, "");
2792 return mem;
2793 }
2794
2795 //=============================================================================
2796 // Do not match memory edge.
2797 uint StrIntrinsicNode::match_edge(uint idx) const {
2798 return idx == 2 || idx == 3;
2799 }
2800
2801 //------------------------------Ideal------------------------------------------
2802 // Return a node which is more "ideal" than the current node. Strip out
2803 // control copies
2804 Node *StrIntrinsicNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2805 if (remove_dead_region(phase, can_reshape)) return this;
2806 // Don't bother trying to transform a dead node
2807 if (in(0) && in(0)->is_top()) return NULL;
2808
2809 if (can_reshape) {
2810 Node* mem = phase->transform(in(MemNode::Memory));
2811 // If transformed to a MergeMem, get the desired slice
2812 uint alias_idx = phase->C->get_alias_index(adr_type());
2813 mem = mem->is_MergeMem() ? mem->as_MergeMem()->memory_at(alias_idx) : mem;
2814 if (mem != in(MemNode::Memory)) {
2815 set_req(MemNode::Memory, mem);
2816 return this;
2817 }
2818 }
2819 return NULL;
2820 }
2821
2822 //------------------------------Value------------------------------------------
2823 const Type *StrIntrinsicNode::Value( PhaseTransform *phase ) const {
2824 if (in(0) && phase->type(in(0)) == Type::TOP) return Type::TOP;
2825 return bottom_type();
2826 }
2827
2828 //=============================================================================
2829 //------------------------------match_edge-------------------------------------
2830 // Do not match memory edge
2831 uint EncodeISOArrayNode::match_edge(uint idx) const {
2832 return idx == 2 || idx == 3; // EncodeISOArray src (Binary dst len)
2833 }
2834
2835 //------------------------------Ideal------------------------------------------
2836 // Return a node which is more "ideal" than the current node. Strip out
2837 // control copies
2838 Node *EncodeISOArrayNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2839 return remove_dead_region(phase, can_reshape) ? this : NULL;
2840 }
2841
2842 //------------------------------Value------------------------------------------
2843 const Type *EncodeISOArrayNode::Value(PhaseTransform *phase) const {
2844 if (in(0) && phase->type(in(0)) == Type::TOP) return Type::TOP;
2845 return bottom_type();
2846 }
2847
2848 //=============================================================================
2849 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
2850 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)),
2851 _adr_type(C->get_adr_type(alias_idx))
2852 {
2853 init_class_id(Class_MemBar);
2854 Node* top = C->top();
2855 init_req(TypeFunc::I_O,top);
2856 init_req(TypeFunc::FramePtr,top);
2857 init_req(TypeFunc::ReturnAdr,top);
2858 if (precedent != NULL)
2859 init_req(TypeFunc::Parms, precedent);
2860 }
2861
2862 //------------------------------cmp--------------------------------------------
2863 uint MemBarNode::hash() const { return NO_HASH; }
2864 uint MemBarNode::cmp( const Node &n ) const {
2865 return (&n == this); // Always fail except on self
2866 }
2867
2868 //------------------------------make-------------------------------------------
2869 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
2870 switch (opcode) {
2871 case Op_MemBarAcquire: return new(C) MemBarAcquireNode(C, atp, pn);
2872 case Op_LoadFence: return new(C) LoadFenceNode(C, atp, pn);
2873 case Op_MemBarRelease: return new(C) MemBarReleaseNode(C, atp, pn);
2874 case Op_StoreFence: return new(C) StoreFenceNode(C, atp, pn);
2875 case Op_MemBarAcquireLock: return new(C) MemBarAcquireLockNode(C, atp, pn);
2876 case Op_MemBarReleaseLock: return new(C) MemBarReleaseLockNode(C, atp, pn);
2877 case Op_MemBarVolatile: return new(C) MemBarVolatileNode(C, atp, pn);
2878 case Op_MemBarCPUOrder: return new(C) MemBarCPUOrderNode(C, atp, pn);
2879 case Op_Initialize: return new(C) InitializeNode(C, atp, pn);
2880 case Op_MemBarStoreStore: return new(C) MemBarStoreStoreNode(C, atp, pn);
2881 default: ShouldNotReachHere(); return NULL;
2882 }
2883 }
2884
2885 //------------------------------Ideal------------------------------------------
2886 // Return a node which is more "ideal" than the current node. Strip out
2887 // control copies
2888 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2889 if (remove_dead_region(phase, can_reshape)) return this;
2890 // Don't bother trying to transform a dead node
2891 if (in(0) && in(0)->is_top()) {
2892 return NULL;
2893 }
2894
2895 // Eliminate volatile MemBars for scalar replaced objects.
2896 if (can_reshape && req() == (Precedent+1)) {
2897 bool eliminate = false;
2898 int opc = Opcode();
2899 if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) {
2900 // Volatile field loads and stores.
2901 Node* my_mem = in(MemBarNode::Precedent);
2902 // The MembarAquire may keep an unused LoadNode alive through the Precedent edge
2903 if ((my_mem != NULL) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) {
2904 // if the Precedent is a decodeN and its input (a Load) is used at more than one place,
2905 // replace this Precedent (decodeN) with the Load instead.
2906 if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1)) {
2907 Node* load_node = my_mem->in(1);
2908 set_req(MemBarNode::Precedent, load_node);
2909 phase->is_IterGVN()->_worklist.push(my_mem);
2910 my_mem = load_node;
2911 } else {
2912 assert(my_mem->unique_out() == this, "sanity");
2913 del_req(Precedent);
2914 phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later
2915 my_mem = NULL;
2916 }
2917 }
2918 if (my_mem != NULL && my_mem->is_Mem()) {
2919 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
2920 // Check for scalar replaced object reference.
2921 if( t_oop != NULL && t_oop->is_known_instance_field() &&
2922 t_oop->offset() != Type::OffsetBot &&
2923 t_oop->offset() != Type::OffsetTop) {
2924 eliminate = true;
2925 }
2926 }
2927 } else if (opc == Op_MemBarRelease) {
2928 // Final field stores.
2929 Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent), phase);
2930 if ((alloc != NULL) && alloc->is_Allocate() &&
2931 AARCH64_ONLY ( alloc->as_Allocate()->does_not_escape_thread() )
2932 NOT_AARCH64 ( alloc->as_Allocate()->_is_non_escaping )
2933 ) {
2934 // The allocated object does not escape.
2935 eliminate = true;
2936 }
2937 }
2938 if (eliminate) {
2939 // Replace MemBar projections by its inputs.
2940 PhaseIterGVN* igvn = phase->is_IterGVN();
2941 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
2942 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
2943 // Must return either the original node (now dead) or a new node
2944 // (Do not return a top here, since that would break the uniqueness of top.)
2945 return new (phase->C) ConINode(TypeInt::ZERO);
2946 }
2947 }
2948 return NULL;
2949 }
2950
2951 //------------------------------Value------------------------------------------
2952 const Type *MemBarNode::Value( PhaseTransform *phase ) const {
2953 if( !in(0) ) return Type::TOP;
2954 if( phase->type(in(0)) == Type::TOP )
2955 return Type::TOP;
2956 return TypeTuple::MEMBAR;
2957 }
2958
2959 //------------------------------match------------------------------------------
2960 // Construct projections for memory.
2961 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) {
2962 switch (proj->_con) {
2963 case TypeFunc::Control:
2964 case TypeFunc::Memory:
2965 return new (m->C) MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
2966 }
2967 ShouldNotReachHere();
2968 return NULL;
2969 }
2970
2971 //===========================InitializeNode====================================
2972 // SUMMARY:
2973 // This node acts as a memory barrier on raw memory, after some raw stores.
2974 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
2975 // The Initialize can 'capture' suitably constrained stores as raw inits.
2976 // It can coalesce related raw stores into larger units (called 'tiles').
2977 // It can avoid zeroing new storage for memory units which have raw inits.
2978 // At macro-expansion, it is marked 'complete', and does not optimize further.
2979 //
2980 // EXAMPLE:
2981 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
2982 // ctl = incoming control; mem* = incoming memory
2983 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
2984 // First allocate uninitialized memory and fill in the header:
2985 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
2986 // ctl := alloc.Control; mem* := alloc.Memory*
2987 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
2988 // Then initialize to zero the non-header parts of the raw memory block:
2989 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
2990 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
2991 // After the initialize node executes, the object is ready for service:
2992 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
2993 // Suppose its body is immediately initialized as {1,2}:
2994 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
2995 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
2996 // mem.SLICE(#short[*]) := store2
2997 //
2998 // DETAILS:
2999 // An InitializeNode collects and isolates object initialization after
3000 // an AllocateNode and before the next possible safepoint. As a
3001 // memory barrier (MemBarNode), it keeps critical stores from drifting
3002 // down past any safepoint or any publication of the allocation.
3003 // Before this barrier, a newly-allocated object may have uninitialized bits.
3004 // After this barrier, it may be treated as a real oop, and GC is allowed.
3005 //
3006 // The semantics of the InitializeNode include an implicit zeroing of
3007 // the new object from object header to the end of the object.
3008 // (The object header and end are determined by the AllocateNode.)
3009 //
3010 // Certain stores may be added as direct inputs to the InitializeNode.
3011 // These stores must update raw memory, and they must be to addresses
3012 // derived from the raw address produced by AllocateNode, and with
3013 // a constant offset. They must be ordered by increasing offset.
3014 // The first one is at in(RawStores), the last at in(req()-1).
3015 // Unlike most memory operations, they are not linked in a chain,
3016 // but are displayed in parallel as users of the rawmem output of
3017 // the allocation.
3018 //
3019 // (See comments in InitializeNode::capture_store, which continue
3020 // the example given above.)
3021 //
3022 // When the associated Allocate is macro-expanded, the InitializeNode
3023 // may be rewritten to optimize collected stores. A ClearArrayNode
3024 // may also be created at that point to represent any required zeroing.
3025 // The InitializeNode is then marked 'complete', prohibiting further
3026 // capturing of nearby memory operations.
3027 //
3028 // During macro-expansion, all captured initializations which store
3029 // constant values of 32 bits or smaller are coalesced (if advantageous)
3030 // into larger 'tiles' 32 or 64 bits. This allows an object to be
3031 // initialized in fewer memory operations. Memory words which are
3032 // covered by neither tiles nor non-constant stores are pre-zeroed
3033 // by explicit stores of zero. (The code shape happens to do all
3034 // zeroing first, then all other stores, with both sequences occurring
3035 // in order of ascending offsets.)
3036 //
3037 // Alternatively, code may be inserted between an AllocateNode and its
3038 // InitializeNode, to perform arbitrary initialization of the new object.
3039 // E.g., the object copying intrinsics insert complex data transfers here.
3040 // The initialization must then be marked as 'complete' disable the
3041 // built-in zeroing semantics and the collection of initializing stores.
3042 //
3043 // While an InitializeNode is incomplete, reads from the memory state
3044 // produced by it are optimizable if they match the control edge and
3045 // new oop address associated with the allocation/initialization.
3046 // They return a stored value (if the offset matches) or else zero.
3047 // A write to the memory state, if it matches control and address,
3048 // and if it is to a constant offset, may be 'captured' by the
3049 // InitializeNode. It is cloned as a raw memory operation and rewired
3050 // inside the initialization, to the raw oop produced by the allocation.
3051 // Operations on addresses which are provably distinct (e.g., to
3052 // other AllocateNodes) are allowed to bypass the initialization.
3053 //
3054 // The effect of all this is to consolidate object initialization
3055 // (both arrays and non-arrays, both piecewise and bulk) into a
3056 // single location, where it can be optimized as a unit.
3057 //
3058 // Only stores with an offset less than TrackedInitializationLimit words
3059 // will be considered for capture by an InitializeNode. This puts a
3060 // reasonable limit on the complexity of optimized initializations.
3061
3062 //---------------------------InitializeNode------------------------------------
3063 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
3064 : _is_complete(Incomplete), _does_not_escape(false),
3065 MemBarNode(C, adr_type, rawoop)
3066 {
3067 init_class_id(Class_Initialize);
3068
3069 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
3070 assert(in(RawAddress) == rawoop, "proper init");
3071 // Note: allocation() can be NULL, for secondary initialization barriers
3072 }
3073
3074 // Since this node is not matched, it will be processed by the
3075 // register allocator. Declare that there are no constraints
3076 // on the allocation of the RawAddress edge.
3077 const RegMask &InitializeNode::in_RegMask(uint idx) const {
3078 // This edge should be set to top, by the set_complete. But be conservative.
3079 if (idx == InitializeNode::RawAddress)
3080 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
3081 return RegMask::Empty;
3082 }
3083
3084 Node* InitializeNode::memory(uint alias_idx) {
3085 Node* mem = in(Memory);
3086 if (mem->is_MergeMem()) {
3087 return mem->as_MergeMem()->memory_at(alias_idx);
3088 } else {
3089 // incoming raw memory is not split
3090 return mem;
3091 }
3092 }
3093
3094 bool InitializeNode::is_non_zero() {
3095 if (is_complete()) return false;
3096 remove_extra_zeroes();
3097 return (req() > RawStores);
3098 }
3099
3100 void InitializeNode::set_complete(PhaseGVN* phase) {
3101 assert(!is_complete(), "caller responsibility");
3102 _is_complete = Complete;
3103
3104 // After this node is complete, it contains a bunch of
3105 // raw-memory initializations. There is no need for
3106 // it to have anything to do with non-raw memory effects.
3107 // Therefore, tell all non-raw users to re-optimize themselves,
3108 // after skipping the memory effects of this initialization.
3109 PhaseIterGVN* igvn = phase->is_IterGVN();
3110 if (igvn) igvn->add_users_to_worklist(this);
3111 }
3112
3113 // convenience function
3114 // return false if the init contains any stores already
3115 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
3116 InitializeNode* init = initialization();
3117 if (init == NULL || init->is_complete()) return false;
3118 init->remove_extra_zeroes();
3119 // for now, if this allocation has already collected any inits, bail:
3120 if (init->is_non_zero()) return false;
3121 init->set_complete(phase);
3122 return true;
3123 }
3124
3125 void InitializeNode::remove_extra_zeroes() {
3126 if (req() == RawStores) return;
3127 Node* zmem = zero_memory();
3128 uint fill = RawStores;
3129 for (uint i = fill; i < req(); i++) {
3130 Node* n = in(i);
3131 if (n->is_top() || n == zmem) continue; // skip
3132 if (fill < i) set_req(fill, n); // compact
3133 ++fill;
3134 }
3135 // delete any empty spaces created:
3136 while (fill < req()) {
3137 del_req(fill);
3138 }
3139 }
3140
3141 // Helper for remembering which stores go with which offsets.
3142 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) {
3143 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
3144 intptr_t offset = -1;
3145 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
3146 phase, offset);
3147 if (base == NULL) return -1; // something is dead,
3148 if (offset < 0) return -1; // dead, dead
3149 return offset;
3150 }
3151
3152 // Helper for proving that an initialization expression is
3153 // "simple enough" to be folded into an object initialization.
3154 // Attempts to prove that a store's initial value 'n' can be captured
3155 // within the initialization without creating a vicious cycle, such as:
3156 // { Foo p = new Foo(); p.next = p; }
3157 // True for constants and parameters and small combinations thereof.
3158 bool InitializeNode::detect_init_independence(Node* n, int& count) {
3159 if (n == NULL) return true; // (can this really happen?)
3160 if (n->is_Proj()) n = n->in(0);
3161 if (n == this) return false; // found a cycle
3162 if (n->is_Con()) return true;
3163 if (n->is_Start()) return true; // params, etc., are OK
3164 if (n->is_Root()) return true; // even better
3165
3166 Node* ctl = n->in(0);
3167 if (ctl != NULL && !ctl->is_top()) {
3168 if (ctl->is_Proj()) ctl = ctl->in(0);
3169 if (ctl == this) return false;
3170
3171 // If we already know that the enclosing memory op is pinned right after
3172 // the init, then any control flow that the store has picked up
3173 // must have preceded the init, or else be equal to the init.
3174 // Even after loop optimizations (which might change control edges)
3175 // a store is never pinned *before* the availability of its inputs.
3176 if (!MemNode::all_controls_dominate(n, this))
3177 return false; // failed to prove a good control
3178 }
3179
3180 // Check data edges for possible dependencies on 'this'.
3181 if ((count += 1) > 20) return false; // complexity limit
3182 for (uint i = 1; i < n->req(); i++) {
3183 Node* m = n->in(i);
3184 if (m == NULL || m == n || m->is_top()) continue;
3185 uint first_i = n->find_edge(m);
3186 if (i != first_i) continue; // process duplicate edge just once
3187 if (!detect_init_independence(m, count)) {
3188 return false;
3189 }
3190 }
3191
3192 return true;
3193 }
3194
3195 // Here are all the checks a Store must pass before it can be moved into
3196 // an initialization. Returns zero if a check fails.
3197 // On success, returns the (constant) offset to which the store applies,
3198 // within the initialized memory.
3199 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase, bool can_reshape) {
3200 const int FAIL = 0;
3201 if (st->is_unaligned_access()) {
3202 return FAIL;
3203 }
3204 if (st->req() != MemNode::ValueIn + 1)
3205 return FAIL; // an inscrutable StoreNode (card mark?)
3206 Node* ctl = st->in(MemNode::Control);
3207 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this))
3208 return FAIL; // must be unconditional after the initialization
3209 Node* mem = st->in(MemNode::Memory);
3210 if (!(mem->is_Proj() && mem->in(0) == this))
3211 return FAIL; // must not be preceded by other stores
3212 Node* adr = st->in(MemNode::Address);
3213 intptr_t offset;
3214 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
3215 if (alloc == NULL)
3216 return FAIL; // inscrutable address
3217 if (alloc != allocation())
3218 return FAIL; // wrong allocation! (store needs to float up)
3219 Node* val = st->in(MemNode::ValueIn);
3220 int complexity_count = 0;
3221 if (!detect_init_independence(val, complexity_count))
3222 return FAIL; // stored value must be 'simple enough'
3223
3224 // The Store can be captured only if nothing after the allocation
3225 // and before the Store is using the memory location that the store
3226 // overwrites.
3227 bool failed = false;
3228 // If is_complete_with_arraycopy() is true the shape of the graph is
3229 // well defined and is safe so no need for extra checks.
3230 if (!is_complete_with_arraycopy()) {
3231 // We are going to look at each use of the memory state following
3232 // the allocation to make sure nothing reads the memory that the
3233 // Store writes.
3234 const TypePtr* t_adr = phase->type(adr)->isa_ptr();
3235 int alias_idx = phase->C->get_alias_index(t_adr);
3236 ResourceMark rm;
3237 Unique_Node_List mems;
3238 mems.push(mem);
3239 Node* unique_merge = NULL;
3240 for (uint next = 0; next < mems.size(); ++next) {
3241 Node *m = mems.at(next);
3242 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
3243 Node *n = m->fast_out(j);
3244 if (n->outcnt() == 0) {
3245 continue;
3246 }
3247 if (n == st) {
3248 continue;
3249 } else if (n->in(0) != NULL && n->in(0) != ctl) {
3250 // If the control of this use is different from the control
3251 // of the Store which is right after the InitializeNode then
3252 // this node cannot be between the InitializeNode and the
3253 // Store.
3254 continue;
3255 } else if (n->is_MergeMem()) {
3256 if (n->as_MergeMem()->memory_at(alias_idx) == m) {
3257 // We can hit a MergeMemNode (that will likely go away
3258 // later) that is a direct use of the memory state
3259 // following the InitializeNode on the same slice as the
3260 // store node that we'd like to capture. We need to check
3261 // the uses of the MergeMemNode.
3262 mems.push(n);
3263 }
3264 } else if (n->is_Mem()) {
3265 Node* other_adr = n->in(MemNode::Address);
3266 if (other_adr == adr) {
3267 failed = true;
3268 break;
3269 } else {
3270 const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr();
3271 if (other_t_adr != NULL) {
3272 int other_alias_idx = phase->C->get_alias_index(other_t_adr);
3273 if (other_alias_idx == alias_idx) {
3274 // A load from the same memory slice as the store right
3275 // after the InitializeNode. We check the control of the
3276 // object/array that is loaded from. If it's the same as
3277 // the store control then we cannot capture the store.
3278 assert(!n->is_Store(), "2 stores to same slice on same control?");
3279 Node* base = other_adr;
3280 assert(base->is_AddP(), err_msg_res("should be addp but is %s", base->Name()));
3281 base = base->in(AddPNode::Base);
3282 if (base != NULL) {
3283 base = base->uncast();
3284 if (base->is_Proj() && base->in(0) == alloc) {
3285 failed = true;
3286 break;
3287 }
3288 }
3289 }
3290 }
3291 }
3292 } else {
3293 failed = true;
3294 break;
3295 }
3296 }
3297 }
3298 }
3299 if (failed) {
3300 if (!can_reshape) {
3301 // We decided we couldn't capture the store during parsing. We
3302 // should try again during the next IGVN once the graph is
3303 // cleaner.
3304 phase->C->record_for_igvn(st);
3305 }
3306 return FAIL;
3307 }
3308
3309 return offset; // success
3310 }
3311
3312 // Find the captured store in(i) which corresponds to the range
3313 // [start..start+size) in the initialized object.
3314 // If there is one, return its index i. If there isn't, return the
3315 // negative of the index where it should be inserted.
3316 // Return 0 if the queried range overlaps an initialization boundary
3317 // or if dead code is encountered.
3318 // If size_in_bytes is zero, do not bother with overlap checks.
3319 int InitializeNode::captured_store_insertion_point(intptr_t start,
3320 int size_in_bytes,
3321 PhaseTransform* phase) {
3322 const int FAIL = 0, MAX_STORE = BytesPerLong;
3323
3324 if (is_complete())
3325 return FAIL; // arraycopy got here first; punt
3326
3327 assert(allocation() != NULL, "must be present");
3328
3329 // no negatives, no header fields:
3330 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
3331
3332 // after a certain size, we bail out on tracking all the stores:
3333 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3334 if (start >= ti_limit) return FAIL;
3335
3336 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
3337 if (i >= limit) return -(int)i; // not found; here is where to put it
3338
3339 Node* st = in(i);
3340 intptr_t st_off = get_store_offset(st, phase);
3341 if (st_off < 0) {
3342 if (st != zero_memory()) {
3343 return FAIL; // bail out if there is dead garbage
3344 }
3345 } else if (st_off > start) {
3346 // ...we are done, since stores are ordered
3347 if (st_off < start + size_in_bytes) {
3348 return FAIL; // the next store overlaps
3349 }
3350 return -(int)i; // not found; here is where to put it
3351 } else if (st_off < start) {
3352 if (size_in_bytes != 0 &&
3353 start < st_off + MAX_STORE &&
3354 start < st_off + st->as_Store()->memory_size()) {
3355 return FAIL; // the previous store overlaps
3356 }
3357 } else {
3358 if (size_in_bytes != 0 &&
3359 st->as_Store()->memory_size() != size_in_bytes) {
3360 return FAIL; // mismatched store size
3361 }
3362 return i;
3363 }
3364
3365 ++i;
3366 }
3367 }
3368
3369 // Look for a captured store which initializes at the offset 'start'
3370 // with the given size. If there is no such store, and no other
3371 // initialization interferes, then return zero_memory (the memory
3372 // projection of the AllocateNode).
3373 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
3374 PhaseTransform* phase) {
3375 assert(stores_are_sane(phase), "");
3376 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3377 if (i == 0) {
3378 return NULL; // something is dead
3379 } else if (i < 0) {
3380 return zero_memory(); // just primordial zero bits here
3381 } else {
3382 Node* st = in(i); // here is the store at this position
3383 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
3384 return st;
3385 }
3386 }
3387
3388 // Create, as a raw pointer, an address within my new object at 'offset'.
3389 Node* InitializeNode::make_raw_address(intptr_t offset,
3390 PhaseTransform* phase) {
3391 Node* addr = in(RawAddress);
3392 if (offset != 0) {
3393 Compile* C = phase->C;
3394 addr = phase->transform( new (C) AddPNode(C->top(), addr,
3395 phase->MakeConX(offset)) );
3396 }
3397 return addr;
3398 }
3399
3400 // Clone the given store, converting it into a raw store
3401 // initializing a field or element of my new object.
3402 // Caller is responsible for retiring the original store,
3403 // with subsume_node or the like.
3404 //
3405 // From the example above InitializeNode::InitializeNode,
3406 // here are the old stores to be captured:
3407 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3408 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3409 //
3410 // Here is the changed code; note the extra edges on init:
3411 // alloc = (Allocate ...)
3412 // rawoop = alloc.RawAddress
3413 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
3414 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
3415 // init = (Initialize alloc.Control alloc.Memory rawoop
3416 // rawstore1 rawstore2)
3417 //
3418 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
3419 PhaseTransform* phase, bool can_reshape) {
3420 assert(stores_are_sane(phase), "");
3421
3422 if (start < 0) return NULL;
3423 assert(can_capture_store(st, phase, can_reshape) == start, "sanity");
3424
3425 Compile* C = phase->C;
3426 int size_in_bytes = st->memory_size();
3427 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3428 if (i == 0) return NULL; // bail out
3429 Node* prev_mem = NULL; // raw memory for the captured store
3430 if (i > 0) {
3431 prev_mem = in(i); // there is a pre-existing store under this one
3432 set_req(i, C->top()); // temporarily disconnect it
3433 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
3434 } else {
3435 i = -i; // no pre-existing store
3436 prev_mem = zero_memory(); // a slice of the newly allocated object
3437 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
3438 set_req(--i, C->top()); // reuse this edge; it has been folded away
3439 else
3440 ins_req(i, C->top()); // build a new edge
3441 }
3442 Node* new_st = st->clone();
3443 new_st->set_req(MemNode::Control, in(Control));
3444 new_st->set_req(MemNode::Memory, prev_mem);
3445 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
3446 new_st = phase->transform(new_st);
3447
3448 // At this point, new_st might have swallowed a pre-existing store
3449 // at the same offset, or perhaps new_st might have disappeared,
3450 // if it redundantly stored the same value (or zero to fresh memory).
3451
3452 // In any case, wire it in:
3453 set_req(i, new_st);
3454
3455 // The caller may now kill the old guy.
3456 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
3457 assert(check_st == new_st || check_st == NULL, "must be findable");
3458 assert(!is_complete(), "");
3459 return new_st;
3460 }
3461
3462 static bool store_constant(jlong* tiles, int num_tiles,
3463 intptr_t st_off, int st_size,
3464 jlong con) {
3465 if ((st_off & (st_size-1)) != 0)
3466 return false; // strange store offset (assume size==2**N)
3467 address addr = (address)tiles + st_off;
3468 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
3469 switch (st_size) {
3470 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
3471 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
3472 case sizeof(jint): *(jint*) addr = (jint) con; break;
3473 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
3474 default: return false; // strange store size (detect size!=2**N here)
3475 }
3476 return true; // return success to caller
3477 }
3478
3479 // Coalesce subword constants into int constants and possibly
3480 // into long constants. The goal, if the CPU permits,
3481 // is to initialize the object with a small number of 64-bit tiles.
3482 // Also, convert floating-point constants to bit patterns.
3483 // Non-constants are not relevant to this pass.
3484 //
3485 // In terms of the running example on InitializeNode::InitializeNode
3486 // and InitializeNode::capture_store, here is the transformation
3487 // of rawstore1 and rawstore2 into rawstore12:
3488 // alloc = (Allocate ...)
3489 // rawoop = alloc.RawAddress
3490 // tile12 = 0x00010002
3491 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
3492 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
3493 //
3494 void
3495 InitializeNode::coalesce_subword_stores(intptr_t header_size,
3496 Node* size_in_bytes,
3497 PhaseGVN* phase) {
3498 Compile* C = phase->C;
3499
3500 assert(stores_are_sane(phase), "");
3501 // Note: After this pass, they are not completely sane,
3502 // since there may be some overlaps.
3503
3504 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
3505
3506 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3507 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
3508 size_limit = MIN2(size_limit, ti_limit);
3509 size_limit = align_size_up(size_limit, BytesPerLong);
3510 int num_tiles = size_limit / BytesPerLong;
3511
3512 // allocate space for the tile map:
3513 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
3514 jlong tiles_buf[small_len];
3515 Node* nodes_buf[small_len];
3516 jlong inits_buf[small_len];
3517 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
3518 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3519 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
3520 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
3521 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
3522 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3523 // tiles: exact bitwise model of all primitive constants
3524 // nodes: last constant-storing node subsumed into the tiles model
3525 // inits: which bytes (in each tile) are touched by any initializations
3526
3527 //// Pass A: Fill in the tile model with any relevant stores.
3528
3529 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
3530 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
3531 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
3532 Node* zmem = zero_memory(); // initially zero memory state
3533 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3534 Node* st = in(i);
3535 intptr_t st_off = get_store_offset(st, phase);
3536
3537 // Figure out the store's offset and constant value:
3538 if (st_off < header_size) continue; //skip (ignore header)
3539 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
3540 int st_size = st->as_Store()->memory_size();
3541 if (st_off + st_size > size_limit) break;
3542
3543 // Record which bytes are touched, whether by constant or not.
3544 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
3545 continue; // skip (strange store size)
3546
3547 const Type* val = phase->type(st->in(MemNode::ValueIn));
3548 if (!val->singleton()) continue; //skip (non-con store)
3549 BasicType type = val->basic_type();
3550
3551 jlong con = 0;
3552 switch (type) {
3553 case T_INT: con = val->is_int()->get_con(); break;
3554 case T_LONG: con = val->is_long()->get_con(); break;
3555 case T_FLOAT: con = jint_cast(val->getf()); break;
3556 case T_DOUBLE: con = jlong_cast(val->getd()); break;
3557 default: continue; //skip (odd store type)
3558 }
3559
3560 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
3561 st->Opcode() == Op_StoreL) {
3562 continue; // This StoreL is already optimal.
3563 }
3564
3565 // Store down the constant.
3566 store_constant(tiles, num_tiles, st_off, st_size, con);
3567
3568 intptr_t j = st_off >> LogBytesPerLong;
3569
3570 if (type == T_INT && st_size == BytesPerInt
3571 && (st_off & BytesPerInt) == BytesPerInt) {
3572 jlong lcon = tiles[j];
3573 if (!Matcher::isSimpleConstant64(lcon) &&
3574 st->Opcode() == Op_StoreI) {
3575 // This StoreI is already optimal by itself.
3576 jint* intcon = (jint*) &tiles[j];
3577 intcon[1] = 0; // undo the store_constant()
3578
3579 // If the previous store is also optimal by itself, back up and
3580 // undo the action of the previous loop iteration... if we can.
3581 // But if we can't, just let the previous half take care of itself.
3582 st = nodes[j];
3583 st_off -= BytesPerInt;
3584 con = intcon[0];
3585 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) {
3586 assert(st_off >= header_size, "still ignoring header");
3587 assert(get_store_offset(st, phase) == st_off, "must be");
3588 assert(in(i-1) == zmem, "must be");
3589 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
3590 assert(con == tcon->is_int()->get_con(), "must be");
3591 // Undo the effects of the previous loop trip, which swallowed st:
3592 intcon[0] = 0; // undo store_constant()
3593 set_req(i-1, st); // undo set_req(i, zmem)
3594 nodes[j] = NULL; // undo nodes[j] = st
3595 --old_subword; // undo ++old_subword
3596 }
3597 continue; // This StoreI is already optimal.
3598 }
3599 }
3600
3601 // This store is not needed.
3602 set_req(i, zmem);
3603 nodes[j] = st; // record for the moment
3604 if (st_size < BytesPerLong) // something has changed
3605 ++old_subword; // includes int/float, but who's counting...
3606 else ++old_long;
3607 }
3608
3609 if ((old_subword + old_long) == 0)
3610 return; // nothing more to do
3611
3612 //// Pass B: Convert any non-zero tiles into optimal constant stores.
3613 // Be sure to insert them before overlapping non-constant stores.
3614 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
3615 for (int j = 0; j < num_tiles; j++) {
3616 jlong con = tiles[j];
3617 jlong init = inits[j];
3618 if (con == 0) continue;
3619 jint con0, con1; // split the constant, address-wise
3620 jint init0, init1; // split the init map, address-wise
3621 { union { jlong con; jint intcon[2]; } u;
3622 u.con = con;
3623 con0 = u.intcon[0];
3624 con1 = u.intcon[1];
3625 u.con = init;
3626 init0 = u.intcon[0];
3627 init1 = u.intcon[1];
3628 }
3629
3630 Node* old = nodes[j];
3631 assert(old != NULL, "need the prior store");
3632 intptr_t offset = (j * BytesPerLong);
3633
3634 bool split = !Matcher::isSimpleConstant64(con);
3635
3636 if (offset < header_size) {
3637 assert(offset + BytesPerInt >= header_size, "second int counts");
3638 assert(*(jint*)&tiles[j] == 0, "junk in header");
3639 split = true; // only the second word counts
3640 // Example: int a[] = { 42 ... }
3641 } else if (con0 == 0 && init0 == -1) {
3642 split = true; // first word is covered by full inits
3643 // Example: int a[] = { ... foo(), 42 ... }
3644 } else if (con1 == 0 && init1 == -1) {
3645 split = true; // second word is covered by full inits
3646 // Example: int a[] = { ... 42, foo() ... }
3647 }
3648
3649 // Here's a case where init0 is neither 0 nor -1:
3650 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
3651 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
3652 // In this case the tile is not split; it is (jlong)42.
3653 // The big tile is stored down, and then the foo() value is inserted.
3654 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
3655
3656 Node* ctl = old->in(MemNode::Control);
3657 Node* adr = make_raw_address(offset, phase);
3658 const TypePtr* atp = TypeRawPtr::BOTTOM;
3659
3660 // One or two coalesced stores to plop down.
3661 Node* st[2];
3662 intptr_t off[2];
3663 int nst = 0;
3664 if (!split) {
3665 ++new_long;
3666 off[nst] = offset;
3667 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3668 phase->longcon(con), T_LONG, MemNode::unordered);
3669 } else {
3670 // Omit either if it is a zero.
3671 if (con0 != 0) {
3672 ++new_int;
3673 off[nst] = offset;
3674 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3675 phase->intcon(con0), T_INT, MemNode::unordered);
3676 }
3677 if (con1 != 0) {
3678 ++new_int;
3679 offset += BytesPerInt;
3680 adr = make_raw_address(offset, phase);
3681 off[nst] = offset;
3682 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3683 phase->intcon(con1), T_INT, MemNode::unordered);
3684 }
3685 }
3686
3687 // Insert second store first, then the first before the second.
3688 // Insert each one just before any overlapping non-constant stores.
3689 while (nst > 0) {
3690 Node* st1 = st[--nst];
3691 C->copy_node_notes_to(st1, old);
3692 st1 = phase->transform(st1);
3693 offset = off[nst];
3694 assert(offset >= header_size, "do not smash header");
3695 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
3696 guarantee(ins_idx != 0, "must re-insert constant store");
3697 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
3698 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
3699 set_req(--ins_idx, st1);
3700 else
3701 ins_req(ins_idx, st1);
3702 }
3703 }
3704
3705 if (PrintCompilation && WizardMode)
3706 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
3707 old_subword, old_long, new_int, new_long);
3708 if (C->log() != NULL)
3709 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
3710 old_subword, old_long, new_int, new_long);
3711
3712 // Clean up any remaining occurrences of zmem:
3713 remove_extra_zeroes();
3714 }
3715
3716 // Explore forward from in(start) to find the first fully initialized
3717 // word, and return its offset. Skip groups of subword stores which
3718 // together initialize full words. If in(start) is itself part of a
3719 // fully initialized word, return the offset of in(start). If there
3720 // are no following full-word stores, or if something is fishy, return
3721 // a negative value.
3722 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
3723 int int_map = 0;
3724 intptr_t int_map_off = 0;
3725 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
3726
3727 for (uint i = start, limit = req(); i < limit; i++) {
3728 Node* st = in(i);
3729
3730 intptr_t st_off = get_store_offset(st, phase);
3731 if (st_off < 0) break; // return conservative answer
3732
3733 int st_size = st->as_Store()->memory_size();
3734 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
3735 return st_off; // we found a complete word init
3736 }
3737
3738 // update the map:
3739
3740 intptr_t this_int_off = align_size_down(st_off, BytesPerInt);
3741 if (this_int_off != int_map_off) {
3742 // reset the map:
3743 int_map = 0;
3744 int_map_off = this_int_off;
3745 }
3746
3747 int subword_off = st_off - this_int_off;
3748 int_map |= right_n_bits(st_size) << subword_off;
3749 if ((int_map & FULL_MAP) == FULL_MAP) {
3750 return this_int_off; // we found a complete word init
3751 }
3752
3753 // Did this store hit or cross the word boundary?
3754 intptr_t next_int_off = align_size_down(st_off + st_size, BytesPerInt);
3755 if (next_int_off == this_int_off + BytesPerInt) {
3756 // We passed the current int, without fully initializing it.
3757 int_map_off = next_int_off;
3758 int_map >>= BytesPerInt;
3759 } else if (next_int_off > this_int_off + BytesPerInt) {
3760 // We passed the current and next int.
3761 return this_int_off + BytesPerInt;
3762 }
3763 }
3764
3765 return -1;
3766 }
3767
3768
3769 // Called when the associated AllocateNode is expanded into CFG.
3770 // At this point, we may perform additional optimizations.
3771 // Linearize the stores by ascending offset, to make memory
3772 // activity as coherent as possible.
3773 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
3774 intptr_t header_size,
3775 Node* size_in_bytes,
3776 PhaseGVN* phase) {
3777 assert(!is_complete(), "not already complete");
3778 assert(stores_are_sane(phase), "");
3779 assert(allocation() != NULL, "must be present");
3780
3781 remove_extra_zeroes();
3782
3783 if (ReduceFieldZeroing || ReduceBulkZeroing)
3784 // reduce instruction count for common initialization patterns
3785 coalesce_subword_stores(header_size, size_in_bytes, phase);
3786
3787 Node* zmem = zero_memory(); // initially zero memory state
3788 Node* inits = zmem; // accumulating a linearized chain of inits
3789 #ifdef ASSERT
3790 intptr_t first_offset = allocation()->minimum_header_size();
3791 intptr_t last_init_off = first_offset; // previous init offset
3792 intptr_t last_init_end = first_offset; // previous init offset+size
3793 intptr_t last_tile_end = first_offset; // previous tile offset+size
3794 #endif
3795 intptr_t zeroes_done = header_size;
3796
3797 bool do_zeroing = true; // we might give up if inits are very sparse
3798 int big_init_gaps = 0; // how many large gaps have we seen?
3799
3800 if (ZeroTLAB) do_zeroing = false;
3801 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
3802
3803 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3804 Node* st = in(i);
3805 intptr_t st_off = get_store_offset(st, phase);
3806 if (st_off < 0)
3807 break; // unknown junk in the inits
3808 if (st->in(MemNode::Memory) != zmem)
3809 break; // complicated store chains somehow in list
3810
3811 int st_size = st->as_Store()->memory_size();
3812 intptr_t next_init_off = st_off + st_size;
3813
3814 if (do_zeroing && zeroes_done < next_init_off) {
3815 // See if this store needs a zero before it or under it.
3816 intptr_t zeroes_needed = st_off;
3817
3818 if (st_size < BytesPerInt) {
3819 // Look for subword stores which only partially initialize words.
3820 // If we find some, we must lay down some word-level zeroes first,
3821 // underneath the subword stores.
3822 //
3823 // Examples:
3824 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
3825 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
3826 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
3827 //
3828 // Note: coalesce_subword_stores may have already done this,
3829 // if it was prompted by constant non-zero subword initializers.
3830 // But this case can still arise with non-constant stores.
3831
3832 intptr_t next_full_store = find_next_fullword_store(i, phase);
3833
3834 // In the examples above:
3835 // in(i) p q r s x y z
3836 // st_off 12 13 14 15 12 13 14
3837 // st_size 1 1 1 1 1 1 1
3838 // next_full_s. 12 16 16 16 16 16 16
3839 // z's_done 12 16 16 16 12 16 12
3840 // z's_needed 12 16 16 16 16 16 16
3841 // zsize 0 0 0 0 4 0 4
3842 if (next_full_store < 0) {
3843 // Conservative tack: Zero to end of current word.
3844 zeroes_needed = align_size_up(zeroes_needed, BytesPerInt);
3845 } else {
3846 // Zero to beginning of next fully initialized word.
3847 // Or, don't zero at all, if we are already in that word.
3848 assert(next_full_store >= zeroes_needed, "must go forward");
3849 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
3850 zeroes_needed = next_full_store;
3851 }
3852 }
3853
3854 if (zeroes_needed > zeroes_done) {
3855 intptr_t zsize = zeroes_needed - zeroes_done;
3856 // Do some incremental zeroing on rawmem, in parallel with inits.
3857 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3858 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3859 zeroes_done, zeroes_needed,
3860 phase);
3861 zeroes_done = zeroes_needed;
3862 if (zsize > Matcher::init_array_short_size && ++big_init_gaps > 2)
3863 do_zeroing = false; // leave the hole, next time
3864 }
3865 }
3866
3867 // Collect the store and move on:
3868 st->set_req(MemNode::Memory, inits);
3869 inits = st; // put it on the linearized chain
3870 set_req(i, zmem); // unhook from previous position
3871
3872 if (zeroes_done == st_off)
3873 zeroes_done = next_init_off;
3874
3875 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
3876
3877 #ifdef ASSERT
3878 // Various order invariants. Weaker than stores_are_sane because
3879 // a large constant tile can be filled in by smaller non-constant stores.
3880 assert(st_off >= last_init_off, "inits do not reverse");
3881 last_init_off = st_off;
3882 const Type* val = NULL;
3883 if (st_size >= BytesPerInt &&
3884 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
3885 (int)val->basic_type() < (int)T_OBJECT) {
3886 assert(st_off >= last_tile_end, "tiles do not overlap");
3887 assert(st_off >= last_init_end, "tiles do not overwrite inits");
3888 last_tile_end = MAX2(last_tile_end, next_init_off);
3889 } else {
3890 intptr_t st_tile_end = align_size_up(next_init_off, BytesPerLong);
3891 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
3892 assert(st_off >= last_init_end, "inits do not overlap");
3893 last_init_end = next_init_off; // it's a non-tile
3894 }
3895 #endif //ASSERT
3896 }
3897
3898 remove_extra_zeroes(); // clear out all the zmems left over
3899 add_req(inits);
3900
3901 if (!ZeroTLAB) {
3902 // If anything remains to be zeroed, zero it all now.
3903 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3904 // if it is the last unused 4 bytes of an instance, forget about it
3905 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
3906 if (zeroes_done + BytesPerLong >= size_limit) {
3907 AllocateNode* alloc = allocation();
3908 assert(alloc != NULL, "must be present");
3909 if (alloc != NULL && alloc->Opcode() == Op_Allocate) {
3910 Node* klass_node = alloc->in(AllocateNode::KlassNode);
3911 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass();
3912 if (zeroes_done == k->layout_helper())
3913 zeroes_done = size_limit;
3914 }
3915 }
3916 if (zeroes_done < size_limit) {
3917 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3918 zeroes_done, size_in_bytes, phase);
3919 }
3920 }
3921
3922 set_complete(phase);
3923 return rawmem;
3924 }
3925
3926
3927 #ifdef ASSERT
3928 bool InitializeNode::stores_are_sane(PhaseTransform* phase) {
3929 if (is_complete())
3930 return true; // stores could be anything at this point
3931 assert(allocation() != NULL, "must be present");
3932 intptr_t last_off = allocation()->minimum_header_size();
3933 for (uint i = InitializeNode::RawStores; i < req(); i++) {
3934 Node* st = in(i);
3935 intptr_t st_off = get_store_offset(st, phase);
3936 if (st_off < 0) continue; // ignore dead garbage
3937 if (last_off > st_off) {
3938 tty->print_cr("*** bad store offset at %d: " INTX_FORMAT " > " INTX_FORMAT, i, last_off, st_off);
3939 this->dump(2);
3940 assert(false, "ascending store offsets");
3941 return false;
3942 }
3943 last_off = st_off + st->as_Store()->memory_size();
3944 }
3945 return true;
3946 }
3947 #endif //ASSERT
3948
3949
3950
3951
3952 //============================MergeMemNode=====================================
3953 //
3954 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
3955 // contributing store or call operations. Each contributor provides the memory
3956 // state for a particular "alias type" (see Compile::alias_type). For example,
3957 // if a MergeMem has an input X for alias category #6, then any memory reference
3958 // to alias category #6 may use X as its memory state input, as an exact equivalent
3959 // to using the MergeMem as a whole.
3960 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
3961 //
3962 // (Here, the <N> notation gives the index of the relevant adr_type.)
3963 //
3964 // In one special case (and more cases in the future), alias categories overlap.
3965 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
3966 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
3967 // it is exactly equivalent to that state W:
3968 // MergeMem(<Bot>: W) <==> W
3969 //
3970 // Usually, the merge has more than one input. In that case, where inputs
3971 // overlap (i.e., one is Bot), the narrower alias type determines the memory
3972 // state for that type, and the wider alias type (Bot) fills in everywhere else:
3973 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
3974 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
3975 //
3976 // A merge can take a "wide" memory state as one of its narrow inputs.
3977 // This simply means that the merge observes out only the relevant parts of
3978 // the wide input. That is, wide memory states arriving at narrow merge inputs
3979 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
3980 //
3981 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
3982 // and that memory slices "leak through":
3983 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
3984 //
3985 // But, in such a cascade, repeated memory slices can "block the leak":
3986 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
3987 //
3988 // In the last example, Y is not part of the combined memory state of the
3989 // outermost MergeMem. The system must, of course, prevent unschedulable
3990 // memory states from arising, so you can be sure that the state Y is somehow
3991 // a precursor to state Y'.
3992 //
3993 //
3994 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
3995 // of each MergeMemNode array are exactly the numerical alias indexes, including
3996 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
3997 // Compile::alias_type (and kin) produce and manage these indexes.
3998 //
3999 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
4000 // (Note that this provides quick access to the top node inside MergeMem methods,
4001 // without the need to reach out via TLS to Compile::current.)
4002 //
4003 // As a consequence of what was just described, a MergeMem that represents a full
4004 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
4005 // containing all alias categories.
4006 //
4007 // MergeMem nodes never (?) have control inputs, so in(0) is NULL.
4008 //
4009 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
4010 // a memory state for the alias type <N>, or else the top node, meaning that
4011 // there is no particular input for that alias type. Note that the length of
4012 // a MergeMem is variable, and may be extended at any time to accommodate new
4013 // memory states at larger alias indexes. When merges grow, they are of course
4014 // filled with "top" in the unused in() positions.
4015 //
4016 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
4017 // (Top was chosen because it works smoothly with passes like GCM.)
4018 //
4019 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
4020 // the type of random VM bits like TLS references.) Since it is always the
4021 // first non-Bot memory slice, some low-level loops use it to initialize an
4022 // index variable: for (i = AliasIdxRaw; i < req(); i++).
4023 //
4024 //
4025 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
4026 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
4027 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
4028 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
4029 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
4030 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
4031 //
4032 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
4033 // really that different from the other memory inputs. An abbreviation called
4034 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
4035 //
4036 //
4037 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
4038 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
4039 // that "emerges though" the base memory will be marked as excluding the alias types
4040 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
4041 //
4042 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
4043 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
4044 //
4045 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
4046 // (It is currently unimplemented.) As you can see, the resulting merge is
4047 // actually a disjoint union of memory states, rather than an overlay.
4048 //
4049
4050 //------------------------------MergeMemNode-----------------------------------
4051 Node* MergeMemNode::make_empty_memory() {
4052 Node* empty_memory = (Node*) Compile::current()->top();
4053 assert(empty_memory->is_top(), "correct sentinel identity");
4054 return empty_memory;
4055 }
4056
4057 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
4058 init_class_id(Class_MergeMem);
4059 // all inputs are nullified in Node::Node(int)
4060 // set_input(0, NULL); // no control input
4061
4062 // Initialize the edges uniformly to top, for starters.
4063 Node* empty_mem = make_empty_memory();
4064 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
4065 init_req(i,empty_mem);
4066 }
4067 assert(empty_memory() == empty_mem, "");
4068
4069 if( new_base != NULL && new_base->is_MergeMem() ) {
4070 MergeMemNode* mdef = new_base->as_MergeMem();
4071 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
4072 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
4073 mms.set_memory(mms.memory2());
4074 }
4075 assert(base_memory() == mdef->base_memory(), "");
4076 } else {
4077 set_base_memory(new_base);
4078 }
4079 }
4080
4081 // Make a new, untransformed MergeMem with the same base as 'mem'.
4082 // If mem is itself a MergeMem, populate the result with the same edges.
4083 MergeMemNode* MergeMemNode::make(Compile* C, Node* mem) {
4084 return new(C) MergeMemNode(mem);
4085 }
4086
4087 //------------------------------cmp--------------------------------------------
4088 uint MergeMemNode::hash() const { return NO_HASH; }
4089 uint MergeMemNode::cmp( const Node &n ) const {
4090 return (&n == this); // Always fail except on self
4091 }
4092
4093 //------------------------------Identity---------------------------------------
4094 Node* MergeMemNode::Identity(PhaseTransform *phase) {
4095 // Identity if this merge point does not record any interesting memory
4096 // disambiguations.
4097 Node* base_mem = base_memory();
4098 Node* empty_mem = empty_memory();
4099 if (base_mem != empty_mem) { // Memory path is not dead?
4100 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4101 Node* mem = in(i);
4102 if (mem != empty_mem && mem != base_mem) {
4103 return this; // Many memory splits; no change
4104 }
4105 }
4106 }
4107 return base_mem; // No memory splits; ID on the one true input
4108 }
4109
4110 //------------------------------Ideal------------------------------------------
4111 // This method is invoked recursively on chains of MergeMem nodes
4112 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4113 // Remove chain'd MergeMems
4114 //
4115 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
4116 // relative to the "in(Bot)". Since we are patching both at the same time,
4117 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
4118 // but rewrite each "in(i)" relative to the new "in(Bot)".
4119 Node *progress = NULL;
4120
4121
4122 Node* old_base = base_memory();
4123 Node* empty_mem = empty_memory();
4124 if (old_base == empty_mem)
4125 return NULL; // Dead memory path.
4126
4127 MergeMemNode* old_mbase;
4128 if (old_base != NULL && old_base->is_MergeMem())
4129 old_mbase = old_base->as_MergeMem();
4130 else
4131 old_mbase = NULL;
4132 Node* new_base = old_base;
4133
4134 // simplify stacked MergeMems in base memory
4135 if (old_mbase) new_base = old_mbase->base_memory();
4136
4137 // the base memory might contribute new slices beyond my req()
4138 if (old_mbase) grow_to_match(old_mbase);
4139
4140 // Look carefully at the base node if it is a phi.
4141 PhiNode* phi_base;
4142 if (new_base != NULL && new_base->is_Phi())
4143 phi_base = new_base->as_Phi();
4144 else
4145 phi_base = NULL;
4146
4147 Node* phi_reg = NULL;
4148 uint phi_len = (uint)-1;
4149 if (phi_base != NULL && !phi_base->is_copy()) {
4150 // do not examine phi if degraded to a copy
4151 phi_reg = phi_base->region();
4152 phi_len = phi_base->req();
4153 // see if the phi is unfinished
4154 for (uint i = 1; i < phi_len; i++) {
4155 if (phi_base->in(i) == NULL) {
4156 // incomplete phi; do not look at it yet!
4157 phi_reg = NULL;
4158 phi_len = (uint)-1;
4159 break;
4160 }
4161 }
4162 }
4163
4164 // Note: We do not call verify_sparse on entry, because inputs
4165 // can normalize to the base_memory via subsume_node or similar
4166 // mechanisms. This method repairs that damage.
4167
4168 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
4169
4170 // Look at each slice.
4171 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4172 Node* old_in = in(i);
4173 // calculate the old memory value
4174 Node* old_mem = old_in;
4175 if (old_mem == empty_mem) old_mem = old_base;
4176 assert(old_mem == memory_at(i), "");
4177
4178 // maybe update (reslice) the old memory value
4179
4180 // simplify stacked MergeMems
4181 Node* new_mem = old_mem;
4182 MergeMemNode* old_mmem;
4183 if (old_mem != NULL && old_mem->is_MergeMem())
4184 old_mmem = old_mem->as_MergeMem();
4185 else
4186 old_mmem = NULL;
4187 if (old_mmem == this) {
4188 // This can happen if loops break up and safepoints disappear.
4189 // A merge of BotPtr (default) with a RawPtr memory derived from a
4190 // safepoint can be rewritten to a merge of the same BotPtr with
4191 // the BotPtr phi coming into the loop. If that phi disappears
4192 // also, we can end up with a self-loop of the mergemem.
4193 // In general, if loops degenerate and memory effects disappear,
4194 // a mergemem can be left looking at itself. This simply means
4195 // that the mergemem's default should be used, since there is
4196 // no longer any apparent effect on this slice.
4197 // Note: If a memory slice is a MergeMem cycle, it is unreachable
4198 // from start. Update the input to TOP.
4199 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
4200 }
4201 else if (old_mmem != NULL) {
4202 new_mem = old_mmem->memory_at(i);
4203 }
4204 // else preceding memory was not a MergeMem
4205
4206 // replace equivalent phis (unfortunately, they do not GVN together)
4207 if (new_mem != NULL && new_mem != new_base &&
4208 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) {
4209 if (new_mem->is_Phi()) {
4210 PhiNode* phi_mem = new_mem->as_Phi();
4211 for (uint i = 1; i < phi_len; i++) {
4212 if (phi_base->in(i) != phi_mem->in(i)) {
4213 phi_mem = NULL;
4214 break;
4215 }
4216 }
4217 if (phi_mem != NULL) {
4218 // equivalent phi nodes; revert to the def
4219 new_mem = new_base;
4220 }
4221 }
4222 }
4223
4224 // maybe store down a new value
4225 Node* new_in = new_mem;
4226 if (new_in == new_base) new_in = empty_mem;
4227
4228 if (new_in != old_in) {
4229 // Warning: Do not combine this "if" with the previous "if"
4230 // A memory slice might have be be rewritten even if it is semantically
4231 // unchanged, if the base_memory value has changed.
4232 set_req(i, new_in);
4233 progress = this; // Report progress
4234 }
4235 }
4236
4237 if (new_base != old_base) {
4238 set_req(Compile::AliasIdxBot, new_base);
4239 // Don't use set_base_memory(new_base), because we need to update du.
4240 assert(base_memory() == new_base, "");
4241 progress = this;
4242 }
4243
4244 if( base_memory() == this ) {
4245 // a self cycle indicates this memory path is dead
4246 set_req(Compile::AliasIdxBot, empty_mem);
4247 }
4248
4249 // Resolve external cycles by calling Ideal on a MergeMem base_memory
4250 // Recursion must occur after the self cycle check above
4251 if( base_memory()->is_MergeMem() ) {
4252 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
4253 Node *m = phase->transform(new_mbase); // Rollup any cycles
4254 if( m != NULL && (m->is_top() ||
4255 m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem) ) {
4256 // propagate rollup of dead cycle to self
4257 set_req(Compile::AliasIdxBot, empty_mem);
4258 }
4259 }
4260
4261 if( base_memory() == empty_mem ) {
4262 progress = this;
4263 // Cut inputs during Parse phase only.
4264 // During Optimize phase a dead MergeMem node will be subsumed by Top.
4265 if( !can_reshape ) {
4266 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4267 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
4268 }
4269 }
4270 }
4271
4272 if( !progress && base_memory()->is_Phi() && can_reshape ) {
4273 // Check if PhiNode::Ideal's "Split phis through memory merges"
4274 // transform should be attempted. Look for this->phi->this cycle.
4275 uint merge_width = req();
4276 if (merge_width > Compile::AliasIdxRaw) {
4277 PhiNode* phi = base_memory()->as_Phi();
4278 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
4279 if (phi->in(i) == this) {
4280 phase->is_IterGVN()->_worklist.push(phi);
4281 break;
4282 }
4283 }
4284 }
4285 }
4286
4287 assert(progress || verify_sparse(), "please, no dups of base");
4288 return progress;
4289 }
4290
4291 //-------------------------set_base_memory-------------------------------------
4292 void MergeMemNode::set_base_memory(Node *new_base) {
4293 Node* empty_mem = empty_memory();
4294 set_req(Compile::AliasIdxBot, new_base);
4295 assert(memory_at(req()) == new_base, "must set default memory");
4296 // Clear out other occurrences of new_base:
4297 if (new_base != empty_mem) {
4298 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4299 if (in(i) == new_base) set_req(i, empty_mem);
4300 }
4301 }
4302 }
4303
4304 //------------------------------out_RegMask------------------------------------
4305 const RegMask &MergeMemNode::out_RegMask() const {
4306 return RegMask::Empty;
4307 }
4308
4309 //------------------------------dump_spec--------------------------------------
4310 #ifndef PRODUCT
4311 void MergeMemNode::dump_spec(outputStream *st) const {
4312 st->print(" {");
4313 Node* base_mem = base_memory();
4314 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
4315 Node* mem = memory_at(i);
4316 if (mem == base_mem) { st->print(" -"); continue; }
4317 st->print( " N%d:", mem->_idx );
4318 Compile::current()->get_adr_type(i)->dump_on(st);
4319 }
4320 st->print(" }");
4321 }
4322 #endif // !PRODUCT
4323
4324
4325 #ifdef ASSERT
4326 static bool might_be_same(Node* a, Node* b) {
4327 if (a == b) return true;
4328 if (!(a->is_Phi() || b->is_Phi())) return false;
4329 // phis shift around during optimization
4330 return true; // pretty stupid...
4331 }
4332
4333 // verify a narrow slice (either incoming or outgoing)
4334 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
4335 if (!VerifyAliases) return; // don't bother to verify unless requested
4336 if (is_error_reported()) return; // muzzle asserts when debugging an error
4337 if (Node::in_dump()) return; // muzzle asserts when printing
4338 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
4339 assert(n != NULL, "");
4340 // Elide intervening MergeMem's
4341 while (n->is_MergeMem()) {
4342 n = n->as_MergeMem()->memory_at(alias_idx);
4343 }
4344 Compile* C = Compile::current();
4345 const TypePtr* n_adr_type = n->adr_type();
4346 if (n == m->empty_memory()) {
4347 // Implicit copy of base_memory()
4348 } else if (n_adr_type != TypePtr::BOTTOM) {
4349 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type");
4350 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
4351 } else {
4352 // A few places like make_runtime_call "know" that VM calls are narrow,
4353 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
4354 bool expected_wide_mem = false;
4355 if (n == m->base_memory()) {
4356 expected_wide_mem = true;
4357 } else if (alias_idx == Compile::AliasIdxRaw ||
4358 n == m->memory_at(Compile::AliasIdxRaw)) {
4359 expected_wide_mem = true;
4360 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
4361 // memory can "leak through" calls on channels that
4362 // are write-once. Allow this also.
4363 expected_wide_mem = true;
4364 }
4365 assert(expected_wide_mem, "expected narrow slice replacement");
4366 }
4367 }
4368 #else // !ASSERT
4369 #define verify_memory_slice(m,i,n) (void)(0) // PRODUCT version is no-op
4370 #endif
4371
4372
4373 //-----------------------------memory_at---------------------------------------
4374 Node* MergeMemNode::memory_at(uint alias_idx) const {
4375 assert(alias_idx >= Compile::AliasIdxRaw ||
4376 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0,
4377 "must avoid base_memory and AliasIdxTop");
4378
4379 // Otherwise, it is a narrow slice.
4380 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
4381 Compile *C = Compile::current();
4382 if (is_empty_memory(n)) {
4383 // the array is sparse; empty slots are the "top" node
4384 n = base_memory();
4385 assert(Node::in_dump()
4386 || n == NULL || n->bottom_type() == Type::TOP
4387 || n->adr_type() == NULL // address is TOP
4388 || n->adr_type() == TypePtr::BOTTOM
4389 || n->adr_type() == TypeRawPtr::BOTTOM
4390 || Compile::current()->AliasLevel() == 0,
4391 "must be a wide memory");
4392 // AliasLevel == 0 if we are organizing the memory states manually.
4393 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
4394 } else {
4395 // make sure the stored slice is sane
4396 #ifdef ASSERT
4397 if (is_error_reported() || Node::in_dump()) {
4398 } else if (might_be_same(n, base_memory())) {
4399 // Give it a pass: It is a mostly harmless repetition of the base.
4400 // This can arise normally from node subsumption during optimization.
4401 } else {
4402 verify_memory_slice(this, alias_idx, n);
4403 }
4404 #endif
4405 }
4406 return n;
4407 }
4408
4409 //---------------------------set_memory_at-------------------------------------
4410 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
4411 verify_memory_slice(this, alias_idx, n);
4412 Node* empty_mem = empty_memory();
4413 if (n == base_memory()) n = empty_mem; // collapse default
4414 uint need_req = alias_idx+1;
4415 if (req() < need_req) {
4416 if (n == empty_mem) return; // already the default, so do not grow me
4417 // grow the sparse array
4418 do {
4419 add_req(empty_mem);
4420 } while (req() < need_req);
4421 }
4422 set_req( alias_idx, n );
4423 }
4424
4425
4426
4427 //--------------------------iteration_setup------------------------------------
4428 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
4429 if (other != NULL) {
4430 grow_to_match(other);
4431 // invariant: the finite support of mm2 is within mm->req()
4432 #ifdef ASSERT
4433 for (uint i = req(); i < other->req(); i++) {
4434 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
4435 }
4436 #endif
4437 }
4438 // Replace spurious copies of base_memory by top.
4439 Node* base_mem = base_memory();
4440 if (base_mem != NULL && !base_mem->is_top()) {
4441 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
4442 if (in(i) == base_mem)
4443 set_req(i, empty_memory());
4444 }
4445 }
4446 }
4447
4448 //---------------------------grow_to_match-------------------------------------
4449 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
4450 Node* empty_mem = empty_memory();
4451 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
4452 // look for the finite support of the other memory
4453 for (uint i = other->req(); --i >= req(); ) {
4454 if (other->in(i) != empty_mem) {
4455 uint new_len = i+1;
4456 while (req() < new_len) add_req(empty_mem);
4457 break;
4458 }
4459 }
4460 }
4461
4462 //---------------------------verify_sparse-------------------------------------
4463 #ifndef PRODUCT
4464 bool MergeMemNode::verify_sparse() const {
4465 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
4466 Node* base_mem = base_memory();
4467 // The following can happen in degenerate cases, since empty==top.
4468 if (is_empty_memory(base_mem)) return true;
4469 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4470 assert(in(i) != NULL, "sane slice");
4471 if (in(i) == base_mem) return false; // should have been the sentinel value!
4472 }
4473 return true;
4474 }
4475
4476 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
4477 Node* n;
4478 n = mm->in(idx);
4479 if (mem == n) return true; // might be empty_memory()
4480 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
4481 if (mem == n) return true;
4482 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) {
4483 if (mem == n) return true;
4484 if (n == NULL) break;
4485 }
4486 return false;
4487 }
4488 #endif // !PRODUCT