1 /*
2 * Copyright (c) 1997, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
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23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/systemDictionary.hpp"
27 #include "compiler/compileLog.hpp"
28 #include "memory/allocation.inline.hpp"
29 #include "oops/objArrayKlass.hpp"
30 #include "opto/addnode.hpp"
31 #include "opto/cfgnode.hpp"
32 #include "opto/compile.hpp"
33 #include "opto/connode.hpp"
34 #include "opto/convertnode.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/narrowptrnode.hpp"
41 #include "opto/phaseX.hpp"
42 #include "opto/regmask.hpp"
43 #include "utilities/copy.hpp"
44
45 // Portions of code courtesy of Clifford Click
46
47 // Optimization - Graph Style
48
49 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st);
50
51 //=============================================================================
52 uint MemNode::size_of() const { return sizeof(*this); }
53
54 const TypePtr *MemNode::adr_type() const {
55 Node* adr = in(Address);
56 if (adr == NULL) return NULL; // node is dead
57 const TypePtr* cross_check = NULL;
58 DEBUG_ONLY(cross_check = _adr_type);
59 return calculate_adr_type(adr->bottom_type(), cross_check);
60 }
61
62 #ifndef PRODUCT
63 void MemNode::dump_spec(outputStream *st) const {
64 if (in(Address) == NULL) return; // node is dead
65 #ifndef ASSERT
66 // fake the missing field
67 const TypePtr* _adr_type = NULL;
68 if (in(Address) != NULL)
69 _adr_type = in(Address)->bottom_type()->isa_ptr();
70 #endif
71 dump_adr_type(this, _adr_type, st);
72
73 Compile* C = Compile::current();
74 if( C->alias_type(_adr_type)->is_volatile() )
75 st->print(" Volatile!");
76 }
77
78 void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) {
79 st->print(" @");
80 if (adr_type == NULL) {
81 st->print("NULL");
82 } else {
83 adr_type->dump_on(st);
84 Compile* C = Compile::current();
85 Compile::AliasType* atp = NULL;
86 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type);
87 if (atp == NULL)
88 st->print(", idx=?\?;");
89 else if (atp->index() == Compile::AliasIdxBot)
90 st->print(", idx=Bot;");
91 else if (atp->index() == Compile::AliasIdxTop)
92 st->print(", idx=Top;");
93 else if (atp->index() == Compile::AliasIdxRaw)
94 st->print(", idx=Raw;");
95 else {
96 ciField* field = atp->field();
97 if (field) {
98 st->print(", name=");
99 field->print_name_on(st);
100 }
101 st->print(", idx=%d;", atp->index());
102 }
103 }
104 }
105
106 extern void print_alias_types();
107
108 #endif
109
110 Node *MemNode::optimize_simple_memory_chain(Node *mchain, const TypeOopPtr *t_oop, Node *load, PhaseGVN *phase) {
111 assert((t_oop != NULL), "sanity");
112 bool is_instance = t_oop->is_known_instance_field();
113 bool is_boxed_value_load = t_oop->is_ptr_to_boxed_value() &&
114 (load != NULL) && load->is_Load() &&
115 (phase->is_IterGVN() != NULL);
116 if (!(is_instance || is_boxed_value_load))
117 return mchain; // don't try to optimize non-instance types
118 uint instance_id = t_oop->instance_id();
119 Node *start_mem = phase->C->start()->proj_out(TypeFunc::Memory);
120 Node *prev = NULL;
121 Node *result = mchain;
122 while (prev != result) {
123 prev = result;
124 if (result == start_mem)
125 break; // hit one of our sentinels
126 // skip over a call which does not affect this memory slice
127 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {
128 Node *proj_in = result->in(0);
129 if (proj_in->is_Allocate() && proj_in->_idx == instance_id) {
130 break; // hit one of our sentinels
131 } else if (proj_in->is_Call()) {
132 CallNode *call = proj_in->as_Call();
133 if (!call->may_modify(t_oop, phase)) { // returns false for instances
134 result = call->in(TypeFunc::Memory);
135 }
136 } else if (proj_in->is_Initialize()) {
137 AllocateNode* alloc = proj_in->as_Initialize()->allocation();
138 // Stop if this is the initialization for the object instance which
139 // which contains this memory slice, otherwise skip over it.
140 if ((alloc == NULL) || (alloc->_idx == instance_id)) {
141 break;
142 }
143 if (is_instance) {
144 result = proj_in->in(TypeFunc::Memory);
145 } else if (is_boxed_value_load) {
146 Node* klass = alloc->in(AllocateNode::KlassNode);
147 const TypeKlassPtr* tklass = phase->type(klass)->is_klassptr();
148 if (tklass->klass_is_exact() && !tklass->klass()->equals(t_oop->klass())) {
149 result = proj_in->in(TypeFunc::Memory); // not related allocation
150 }
151 }
152 } else if (proj_in->is_MemBar()) {
153 result = proj_in->in(TypeFunc::Memory);
154 } else {
155 assert(false, "unexpected projection");
156 }
157 } else if (result->is_ClearArray()) {
158 if (!is_instance || !ClearArrayNode::step_through(&result, instance_id, phase)) {
159 // Can not bypass initialization of the instance
160 // we are looking for.
161 break;
162 }
163 // Otherwise skip it (the call updated 'result' value).
164 } else if (result->is_MergeMem()) {
165 result = step_through_mergemem(phase, result->as_MergeMem(), t_oop, NULL, tty);
166 }
167 }
168 return result;
169 }
170
171 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, Node *load, PhaseGVN *phase) {
172 const TypeOopPtr* t_oop = t_adr->isa_oopptr();
173 if (t_oop == NULL)
174 return mchain; // don't try to optimize non-oop types
175 Node* result = optimize_simple_memory_chain(mchain, t_oop, load, phase);
176 bool is_instance = t_oop->is_known_instance_field();
177 PhaseIterGVN *igvn = phase->is_IterGVN();
178 if (is_instance && igvn != NULL && result->is_Phi()) {
179 PhiNode *mphi = result->as_Phi();
180 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
181 const TypePtr *t = mphi->adr_type();
182 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
183 t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
184 t->is_oopptr()->cast_to_exactness(true)
185 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
186 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop) {
187 // clone the Phi with our address type
188 result = mphi->split_out_instance(t_adr, igvn);
189 } else {
190 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain");
191 }
192 }
193 return result;
194 }
195
196 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) {
197 uint alias_idx = phase->C->get_alias_index(tp);
198 Node *mem = mmem;
199 #ifdef ASSERT
200 {
201 // Check that current type is consistent with the alias index used during graph construction
202 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
203 bool consistent = adr_check == NULL || adr_check->empty() ||
204 phase->C->must_alias(adr_check, alias_idx );
205 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
206 if( !consistent && adr_check != NULL && !adr_check->empty() &&
207 tp->isa_aryptr() && tp->offset() == Type::OffsetBot &&
208 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot &&
209 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() ||
210 adr_check->offset() == oopDesc::klass_offset_in_bytes() ||
211 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) {
212 // don't assert if it is dead code.
213 consistent = true;
214 }
215 if( !consistent ) {
216 st->print("alias_idx==%d, adr_check==", alias_idx);
217 if( adr_check == NULL ) {
218 st->print("NULL");
219 } else {
220 adr_check->dump();
221 }
222 st->cr();
223 print_alias_types();
224 assert(consistent, "adr_check must match alias idx");
225 }
226 }
227 #endif
228 // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally
229 // means an array I have not precisely typed yet. Do not do any
230 // alias stuff with it any time soon.
231 const TypeOopPtr *toop = tp->isa_oopptr();
232 if( tp->base() != Type::AnyPtr &&
233 !(toop &&
234 toop->klass() != NULL &&
235 toop->klass()->is_java_lang_Object() &&
236 toop->offset() == Type::OffsetBot) ) {
237 // compress paths and change unreachable cycles to TOP
238 // If not, we can update the input infinitely along a MergeMem cycle
239 // Equivalent code in PhiNode::Ideal
240 Node* m = phase->transform(mmem);
241 // If transformed to a MergeMem, get the desired slice
242 // Otherwise the returned node represents memory for every slice
243 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
244 // Update input if it is progress over what we have now
245 }
246 return mem;
247 }
248
249 //--------------------------Ideal_common---------------------------------------
250 // Look for degenerate control and memory inputs. Bypass MergeMem inputs.
251 // Unhook non-raw memories from complete (macro-expanded) initializations.
252 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
253 // If our control input is a dead region, kill all below the region
254 Node *ctl = in(MemNode::Control);
255 if (ctl && remove_dead_region(phase, can_reshape))
256 return this;
257 ctl = in(MemNode::Control);
258 // Don't bother trying to transform a dead node
259 if (ctl && ctl->is_top()) return NodeSentinel;
260
261 PhaseIterGVN *igvn = phase->is_IterGVN();
262 // Wait if control on the worklist.
263 if (ctl && can_reshape && igvn != NULL) {
264 Node* bol = NULL;
265 Node* cmp = NULL;
266 if (ctl->in(0)->is_If()) {
267 assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity");
268 bol = ctl->in(0)->in(1);
269 if (bol->is_Bool())
270 cmp = ctl->in(0)->in(1)->in(1);
271 }
272 if (igvn->_worklist.member(ctl) ||
273 (bol != NULL && igvn->_worklist.member(bol)) ||
274 (cmp != NULL && igvn->_worklist.member(cmp)) ) {
275 // This control path may be dead.
276 // Delay this memory node transformation until the control is processed.
277 phase->is_IterGVN()->_worklist.push(this);
278 return NodeSentinel; // caller will return NULL
279 }
280 }
281 // Ignore if memory is dead, or self-loop
282 Node *mem = in(MemNode::Memory);
283 if (phase->type( mem ) == Type::TOP) return NodeSentinel; // caller will return NULL
284 assert(mem != this, "dead loop in MemNode::Ideal");
285
286 if (can_reshape && igvn != NULL && igvn->_worklist.member(mem)) {
287 // This memory slice may be dead.
288 // Delay this mem node transformation until the memory is processed.
289 phase->is_IterGVN()->_worklist.push(this);
290 return NodeSentinel; // caller will return NULL
291 }
292
293 Node *address = in(MemNode::Address);
294 const Type *t_adr = phase->type(address);
295 if (t_adr == Type::TOP) return NodeSentinel; // caller will return NULL
296
297 if (can_reshape && igvn != NULL &&
298 (igvn->_worklist.member(address) ||
299 igvn->_worklist.size() > 0 && (t_adr != adr_type())) ) {
300 // The address's base and type may change when the address is processed.
301 // Delay this mem node transformation until the address is processed.
302 phase->is_IterGVN()->_worklist.push(this);
303 return NodeSentinel; // caller will return NULL
304 }
305
306 // Do NOT remove or optimize the next lines: ensure a new alias index
307 // is allocated for an oop pointer type before Escape Analysis.
308 // Note: C++ will not remove it since the call has side effect.
309 if (t_adr->isa_oopptr()) {
310 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr());
311 }
312
313 Node* base = NULL;
314 if (address->is_AddP()) {
315 base = address->in(AddPNode::Base);
316 }
317 if (base != NULL && phase->type(base)->higher_equal(TypePtr::NULL_PTR) &&
318 !t_adr->isa_rawptr()) {
319 // Note: raw address has TOP base and top->higher_equal(TypePtr::NULL_PTR) is true.
320 // Skip this node optimization if its address has TOP base.
321 return NodeSentinel; // caller will return NULL
322 }
323
324 // Avoid independent memory operations
325 Node* old_mem = mem;
326
327 // The code which unhooks non-raw memories from complete (macro-expanded)
328 // initializations was removed. After macro-expansion all stores catched
329 // by Initialize node became raw stores and there is no information
330 // which memory slices they modify. So it is unsafe to move any memory
331 // operation above these stores. Also in most cases hooked non-raw memories
332 // were already unhooked by using information from detect_ptr_independence()
333 // and find_previous_store().
334
335 if (mem->is_MergeMem()) {
336 MergeMemNode* mmem = mem->as_MergeMem();
337 const TypePtr *tp = t_adr->is_ptr();
338
339 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
340 }
341
342 if (mem != old_mem) {
343 set_req(MemNode::Memory, mem);
344 if (can_reshape && old_mem->outcnt() == 0) {
345 igvn->_worklist.push(old_mem);
346 }
347 if (phase->type( mem ) == Type::TOP) return NodeSentinel;
348 return this;
349 }
350
351 // let the subclass continue analyzing...
352 return NULL;
353 }
354
355 // Helper function for proving some simple control dominations.
356 // Attempt to prove that all control inputs of 'dom' dominate 'sub'.
357 // Already assumes that 'dom' is available at 'sub', and that 'sub'
358 // is not a constant (dominated by the method's StartNode).
359 // Used by MemNode::find_previous_store to prove that the
360 // control input of a memory operation predates (dominates)
361 // an allocation it wants to look past.
362 bool MemNode::all_controls_dominate(Node* dom, Node* sub) {
363 if (dom == NULL || dom->is_top() || sub == NULL || sub->is_top())
364 return false; // Conservative answer for dead code
365
366 // Check 'dom'. Skip Proj and CatchProj nodes.
367 dom = dom->find_exact_control(dom);
368 if (dom == NULL || dom->is_top())
369 return false; // Conservative answer for dead code
370
371 if (dom == sub) {
372 // For the case when, for example, 'sub' is Initialize and the original
373 // 'dom' is Proj node of the 'sub'.
374 return false;
375 }
376
377 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub)
378 return true;
379
380 // 'dom' dominates 'sub' if its control edge and control edges
381 // of all its inputs dominate or equal to sub's control edge.
382
383 // Currently 'sub' is either Allocate, Initialize or Start nodes.
384 // Or Region for the check in LoadNode::Ideal();
385 // 'sub' should have sub->in(0) != NULL.
386 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() ||
387 sub->is_Region() || sub->is_Call(), "expecting only these nodes");
388
389 // Get control edge of 'sub'.
390 Node* orig_sub = sub;
391 sub = sub->find_exact_control(sub->in(0));
392 if (sub == NULL || sub->is_top())
393 return false; // Conservative answer for dead code
394
395 assert(sub->is_CFG(), "expecting control");
396
397 if (sub == dom)
398 return true;
399
400 if (sub->is_Start() || sub->is_Root())
401 return false;
402
403 {
404 // Check all control edges of 'dom'.
405
406 ResourceMark rm;
407 Arena* arena = Thread::current()->resource_area();
408 Node_List nlist(arena);
409 Unique_Node_List dom_list(arena);
410
411 dom_list.push(dom);
412 bool only_dominating_controls = false;
413
414 for (uint next = 0; next < dom_list.size(); next++) {
415 Node* n = dom_list.at(next);
416 if (n == orig_sub)
417 return false; // One of dom's inputs dominated by sub.
418 if (!n->is_CFG() && n->pinned()) {
419 // Check only own control edge for pinned non-control nodes.
420 n = n->find_exact_control(n->in(0));
421 if (n == NULL || n->is_top())
422 return false; // Conservative answer for dead code
423 assert(n->is_CFG(), "expecting control");
424 dom_list.push(n);
425 } else if (n->is_Con() || n->is_Start() || n->is_Root()) {
426 only_dominating_controls = true;
427 } else if (n->is_CFG()) {
428 if (n->dominates(sub, nlist))
429 only_dominating_controls = true;
430 else
431 return false;
432 } else {
433 // First, own control edge.
434 Node* m = n->find_exact_control(n->in(0));
435 if (m != NULL) {
436 if (m->is_top())
437 return false; // Conservative answer for dead code
438 dom_list.push(m);
439 }
440 // Now, the rest of edges.
441 uint cnt = n->req();
442 for (uint i = 1; i < cnt; i++) {
443 m = n->find_exact_control(n->in(i));
444 if (m == NULL || m->is_top())
445 continue;
446 dom_list.push(m);
447 }
448 }
449 }
450 return only_dominating_controls;
451 }
452 }
453
454 //---------------------detect_ptr_independence---------------------------------
455 // Used by MemNode::find_previous_store to prove that two base
456 // pointers are never equal.
457 // The pointers are accompanied by their associated allocations,
458 // if any, which have been previously discovered by the caller.
459 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
460 Node* p2, AllocateNode* a2,
461 PhaseTransform* phase) {
462 // Attempt to prove that these two pointers cannot be aliased.
463 // They may both manifestly be allocations, and they should differ.
464 // Or, if they are not both allocations, they can be distinct constants.
465 // Otherwise, one is an allocation and the other a pre-existing value.
466 if (a1 == NULL && a2 == NULL) { // neither an allocation
467 return (p1 != p2) && p1->is_Con() && p2->is_Con();
468 } else if (a1 != NULL && a2 != NULL) { // both allocations
469 return (a1 != a2);
470 } else if (a1 != NULL) { // one allocation a1
471 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.)
472 return all_controls_dominate(p2, a1);
473 } else { //(a2 != NULL) // one allocation a2
474 return all_controls_dominate(p1, a2);
475 }
476 return false;
477 }
478
479
480 // The logic for reordering loads and stores uses four steps:
481 // (a) Walk carefully past stores and initializations which we
482 // can prove are independent of this load.
483 // (b) Observe that the next memory state makes an exact match
484 // with self (load or store), and locate the relevant store.
485 // (c) Ensure that, if we were to wire self directly to the store,
486 // the optimizer would fold it up somehow.
487 // (d) Do the rewiring, and return, depending on some other part of
488 // the optimizer to fold up the load.
489 // This routine handles steps (a) and (b). Steps (c) and (d) are
490 // specific to loads and stores, so they are handled by the callers.
491 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.)
492 //
493 Node* MemNode::find_previous_store(PhaseTransform* phase) {
494 Node* ctrl = in(MemNode::Control);
495 Node* adr = in(MemNode::Address);
496 intptr_t offset = 0;
497 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
498 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase);
499
500 if (offset == Type::OffsetBot)
501 return NULL; // cannot unalias unless there are precise offsets
502
503 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr();
504
505 intptr_t size_in_bytes = memory_size();
506
507 Node* mem = in(MemNode::Memory); // start searching here...
508
509 int cnt = 50; // Cycle limiter
510 for (;;) { // While we can dance past unrelated stores...
511 if (--cnt < 0) break; // Caught in cycle or a complicated dance?
512
513 if (mem->is_Store()) {
514 Node* st_adr = mem->in(MemNode::Address);
515 intptr_t st_offset = 0;
516 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
517 if (st_base == NULL)
518 break; // inscrutable pointer
519 if (st_offset != offset && st_offset != Type::OffsetBot) {
520 const int MAX_STORE = BytesPerLong;
521 if (st_offset >= offset + size_in_bytes ||
522 st_offset <= offset - MAX_STORE ||
523 st_offset <= offset - mem->as_Store()->memory_size()) {
524 // Success: The offsets are provably independent.
525 // (You may ask, why not just test st_offset != offset and be done?
526 // The answer is that stores of different sizes can co-exist
527 // in the same sequence of RawMem effects. We sometimes initialize
528 // a whole 'tile' of array elements with a single jint or jlong.)
529 mem = mem->in(MemNode::Memory);
530 continue; // (a) advance through independent store memory
531 }
532 }
533 if (st_base != base &&
534 detect_ptr_independence(base, alloc,
535 st_base,
536 AllocateNode::Ideal_allocation(st_base, phase),
537 phase)) {
538 // Success: The bases are provably independent.
539 mem = mem->in(MemNode::Memory);
540 continue; // (a) advance through independent store memory
541 }
542
543 // (b) At this point, if the bases or offsets do not agree, we lose,
544 // since we have not managed to prove 'this' and 'mem' independent.
545 if (st_base == base && st_offset == offset) {
546 return mem; // let caller handle steps (c), (d)
547 }
548
549 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
550 InitializeNode* st_init = mem->in(0)->as_Initialize();
551 AllocateNode* st_alloc = st_init->allocation();
552 if (st_alloc == NULL)
553 break; // something degenerated
554 bool known_identical = false;
555 bool known_independent = false;
556 if (alloc == st_alloc)
557 known_identical = true;
558 else if (alloc != NULL)
559 known_independent = true;
560 else if (all_controls_dominate(this, st_alloc))
561 known_independent = true;
562
563 if (known_independent) {
564 // The bases are provably independent: Either they are
565 // manifestly distinct allocations, or else the control
566 // of this load dominates the store's allocation.
567 int alias_idx = phase->C->get_alias_index(adr_type());
568 if (alias_idx == Compile::AliasIdxRaw) {
569 mem = st_alloc->in(TypeFunc::Memory);
570 } else {
571 mem = st_init->memory(alias_idx);
572 }
573 continue; // (a) advance through independent store memory
574 }
575
576 // (b) at this point, if we are not looking at a store initializing
577 // the same allocation we are loading from, we lose.
578 if (known_identical) {
579 // From caller, can_see_stored_value will consult find_captured_store.
580 return mem; // let caller handle steps (c), (d)
581 }
582
583 } else if (addr_t != NULL && addr_t->is_known_instance_field()) {
584 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
585 if (mem->is_Proj() && mem->in(0)->is_Call()) {
586 CallNode *call = mem->in(0)->as_Call();
587 if (!call->may_modify(addr_t, phase)) {
588 mem = call->in(TypeFunc::Memory);
589 continue; // (a) advance through independent call memory
590 }
591 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) {
592 mem = mem->in(0)->in(TypeFunc::Memory);
593 continue; // (a) advance through independent MemBar memory
594 } else if (mem->is_ClearArray()) {
595 if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) {
596 // (the call updated 'mem' value)
597 continue; // (a) advance through independent allocation memory
598 } else {
599 // Can not bypass initialization of the instance
600 // we are looking for.
601 return mem;
602 }
603 } else if (mem->is_MergeMem()) {
604 int alias_idx = phase->C->get_alias_index(adr_type());
605 mem = mem->as_MergeMem()->memory_at(alias_idx);
606 continue; // (a) advance through independent MergeMem memory
607 }
608 }
609
610 // Unless there is an explicit 'continue', we must bail out here,
611 // because 'mem' is an inscrutable memory state (e.g., a call).
612 break;
613 }
614
615 return NULL; // bail out
616 }
617
618 //----------------------calculate_adr_type-------------------------------------
619 // Helper function. Notices when the given type of address hits top or bottom.
620 // Also, asserts a cross-check of the type against the expected address type.
621 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
622 if (t == Type::TOP) return NULL; // does not touch memory any more?
623 #ifdef PRODUCT
624 cross_check = NULL;
625 #else
626 if (!VerifyAliases || is_error_reported() || Node::in_dump()) cross_check = NULL;
627 #endif
628 const TypePtr* tp = t->isa_ptr();
629 if (tp == NULL) {
630 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
631 return TypePtr::BOTTOM; // touches lots of memory
632 } else {
633 #ifdef ASSERT
634 // %%%% [phh] We don't check the alias index if cross_check is
635 // TypeRawPtr::BOTTOM. Needs to be investigated.
636 if (cross_check != NULL &&
637 cross_check != TypePtr::BOTTOM &&
638 cross_check != TypeRawPtr::BOTTOM) {
639 // Recheck the alias index, to see if it has changed (due to a bug).
640 Compile* C = Compile::current();
641 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
642 "must stay in the original alias category");
643 // The type of the address must be contained in the adr_type,
644 // disregarding "null"-ness.
645 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
646 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
647 assert(cross_check->meet(tp_notnull) == cross_check->remove_speculative(),
648 "real address must not escape from expected memory type");
649 }
650 #endif
651 return tp;
652 }
653 }
654
655 //------------------------adr_phi_is_loop_invariant----------------------------
656 // A helper function for Ideal_DU_postCCP to check if a Phi in a counted
657 // loop is loop invariant. Make a quick traversal of Phi and associated
658 // CastPP nodes, looking to see if they are a closed group within the loop.
659 bool MemNode::adr_phi_is_loop_invariant(Node* adr_phi, Node* cast) {
660 // The idea is that the phi-nest must boil down to only CastPP nodes
661 // with the same data. This implies that any path into the loop already
662 // includes such a CastPP, and so the original cast, whatever its input,
663 // must be covered by an equivalent cast, with an earlier control input.
664 ResourceMark rm;
665
666 // The loop entry input of the phi should be the unique dominating
667 // node for every Phi/CastPP in the loop.
668 Unique_Node_List closure;
669 closure.push(adr_phi->in(LoopNode::EntryControl));
670
671 // Add the phi node and the cast to the worklist.
672 Unique_Node_List worklist;
673 worklist.push(adr_phi);
674 if( cast != NULL ){
675 if( !cast->is_ConstraintCast() ) return false;
676 worklist.push(cast);
677 }
678
679 // Begin recursive walk of phi nodes.
680 while( worklist.size() ){
681 // Take a node off the worklist
682 Node *n = worklist.pop();
683 if( !closure.member(n) ){
684 // Add it to the closure.
685 closure.push(n);
686 // Make a sanity check to ensure we don't waste too much time here.
687 if( closure.size() > 20) return false;
688 // This node is OK if:
689 // - it is a cast of an identical value
690 // - or it is a phi node (then we add its inputs to the worklist)
691 // Otherwise, the node is not OK, and we presume the cast is not invariant
692 if( n->is_ConstraintCast() ){
693 worklist.push(n->in(1));
694 } else if( n->is_Phi() ) {
695 for( uint i = 1; i < n->req(); i++ ) {
696 worklist.push(n->in(i));
697 }
698 } else {
699 return false;
700 }
701 }
702 }
703
704 // Quit when the worklist is empty, and we've found no offending nodes.
705 return true;
706 }
707
708 //------------------------------Ideal_DU_postCCP-------------------------------
709 // Find any cast-away of null-ness and keep its control. Null cast-aways are
710 // going away in this pass and we need to make this memory op depend on the
711 // gating null check.
712 Node *MemNode::Ideal_DU_postCCP( PhaseCCP *ccp ) {
713 return Ideal_common_DU_postCCP(ccp, this, in(MemNode::Address));
714 }
715
716 // I tried to leave the CastPP's in. This makes the graph more accurate in
717 // some sense; we get to keep around the knowledge that an oop is not-null
718 // after some test. Alas, the CastPP's interfere with GVN (some values are
719 // the regular oop, some are the CastPP of the oop, all merge at Phi's which
720 // cannot collapse, etc). This cost us 10% on SpecJVM, even when I removed
721 // some of the more trivial cases in the optimizer. Removing more useless
722 // Phi's started allowing Loads to illegally float above null checks. I gave
723 // up on this approach. CNC 10/20/2000
724 // This static method may be called not from MemNode (EncodePNode calls it).
725 // Only the control edge of the node 'n' might be updated.
726 Node *MemNode::Ideal_common_DU_postCCP( PhaseCCP *ccp, Node* n, Node* adr ) {
727 Node *skipped_cast = NULL;
728 // Need a null check? Regular static accesses do not because they are
729 // from constant addresses. Array ops are gated by the range check (which
730 // always includes a NULL check). Just check field ops.
731 if( n->in(MemNode::Control) == NULL ) {
732 // Scan upwards for the highest location we can place this memory op.
733 while( true ) {
734 switch( adr->Opcode() ) {
735
736 case Op_AddP: // No change to NULL-ness, so peek thru AddP's
737 adr = adr->in(AddPNode::Base);
738 continue;
739
740 case Op_DecodeN: // No change to NULL-ness, so peek thru
741 case Op_DecodeNKlass:
742 adr = adr->in(1);
743 continue;
744
745 case Op_EncodeP:
746 case Op_EncodePKlass:
747 // EncodeP node's control edge could be set by this method
748 // when EncodeP node depends on CastPP node.
749 //
750 // Use its control edge for memory op because EncodeP may go away
751 // later when it is folded with following or preceding DecodeN node.
752 if (adr->in(0) == NULL) {
753 // Keep looking for cast nodes.
754 adr = adr->in(1);
755 continue;
756 }
757 ccp->hash_delete(n);
758 n->set_req(MemNode::Control, adr->in(0));
759 ccp->hash_insert(n);
760 return n;
761
762 case Op_CastPP:
763 // If the CastPP is useless, just peek on through it.
764 if( ccp->type(adr) == ccp->type(adr->in(1)) ) {
765 // Remember the cast that we've peeked though. If we peek
766 // through more than one, then we end up remembering the highest
767 // one, that is, if in a loop, the one closest to the top.
768 skipped_cast = adr;
769 adr = adr->in(1);
770 continue;
771 }
772 // CastPP is going away in this pass! We need this memory op to be
773 // control-dependent on the test that is guarding the CastPP.
774 ccp->hash_delete(n);
775 n->set_req(MemNode::Control, adr->in(0));
776 ccp->hash_insert(n);
777 return n;
778
779 case Op_Phi:
780 // Attempt to float above a Phi to some dominating point.
781 if (adr->in(0) != NULL && adr->in(0)->is_CountedLoop()) {
782 // If we've already peeked through a Cast (which could have set the
783 // control), we can't float above a Phi, because the skipped Cast
784 // may not be loop invariant.
785 if (adr_phi_is_loop_invariant(adr, skipped_cast)) {
786 adr = adr->in(1);
787 continue;
788 }
789 }
790
791 // Intentional fallthrough!
792
793 // No obvious dominating point. The mem op is pinned below the Phi
794 // by the Phi itself. If the Phi goes away (no true value is merged)
795 // then the mem op can float, but not indefinitely. It must be pinned
796 // behind the controls leading to the Phi.
797 case Op_CheckCastPP:
798 // These usually stick around to change address type, however a
799 // useless one can be elided and we still need to pick up a control edge
800 if (adr->in(0) == NULL) {
801 // This CheckCastPP node has NO control and is likely useless. But we
802 // need check further up the ancestor chain for a control input to keep
803 // the node in place. 4959717.
804 skipped_cast = adr;
805 adr = adr->in(1);
806 continue;
807 }
808 ccp->hash_delete(n);
809 n->set_req(MemNode::Control, adr->in(0));
810 ccp->hash_insert(n);
811 return n;
812
813 // List of "safe" opcodes; those that implicitly block the memory
814 // op below any null check.
815 case Op_CastX2P: // no null checks on native pointers
816 case Op_Parm: // 'this' pointer is not null
817 case Op_LoadP: // Loading from within a klass
818 case Op_LoadN: // Loading from within a klass
819 case Op_LoadKlass: // Loading from within a klass
820 case Op_LoadNKlass: // Loading from within a klass
821 case Op_ConP: // Loading from a klass
822 case Op_ConN: // Loading from a klass
823 case Op_ConNKlass: // Loading from a klass
824 case Op_CreateEx: // Sucking up the guts of an exception oop
825 case Op_Con: // Reading from TLS
826 case Op_CMoveP: // CMoveP is pinned
827 case Op_CMoveN: // CMoveN is pinned
828 break; // No progress
829
830 case Op_Proj: // Direct call to an allocation routine
831 case Op_SCMemProj: // Memory state from store conditional ops
832 #ifdef ASSERT
833 {
834 assert(adr->as_Proj()->_con == TypeFunc::Parms, "must be return value");
835 const Node* call = adr->in(0);
836 if (call->is_CallJava()) {
837 const CallJavaNode* call_java = call->as_CallJava();
838 const TypeTuple *r = call_java->tf()->range();
839 assert(r->cnt() > TypeFunc::Parms, "must return value");
840 const Type* ret_type = r->field_at(TypeFunc::Parms);
841 assert(ret_type && ret_type->isa_ptr(), "must return pointer");
842 // We further presume that this is one of
843 // new_instance_Java, new_array_Java, or
844 // the like, but do not assert for this.
845 } else if (call->is_Allocate()) {
846 // similar case to new_instance_Java, etc.
847 } else if (!call->is_CallLeaf()) {
848 // Projections from fetch_oop (OSR) are allowed as well.
849 ShouldNotReachHere();
850 }
851 }
852 #endif
853 break;
854 default:
855 ShouldNotReachHere();
856 }
857 break;
858 }
859 }
860
861 return NULL; // No progress
862 }
863
864
865 //=============================================================================
866 // Should LoadNode::Ideal() attempt to remove control edges?
867 bool LoadNode::can_remove_control() const {
868 return true;
869 }
870 uint LoadNode::size_of() const { return sizeof(*this); }
871 uint LoadNode::cmp( const Node &n ) const
872 { return !Type::cmp( _type, ((LoadNode&)n)._type ); }
873 const Type *LoadNode::bottom_type() const { return _type; }
874 uint LoadNode::ideal_reg() const {
875 return _type->ideal_reg();
876 }
877
878 #ifndef PRODUCT
879 void LoadNode::dump_spec(outputStream *st) const {
880 MemNode::dump_spec(st);
881 if( !Verbose && !WizardMode ) {
882 // standard dump does this in Verbose and WizardMode
883 st->print(" #"); _type->dump_on(st);
884 }
885 }
886 #endif
887
888 #ifdef ASSERT
889 //----------------------------is_immutable_value-------------------------------
890 // Helper function to allow a raw load without control edge for some cases
891 bool LoadNode::is_immutable_value(Node* adr) {
892 return (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() &&
893 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal &&
894 (adr->in(AddPNode::Offset)->find_intptr_t_con(-1) ==
895 in_bytes(JavaThread::osthread_offset())));
896 }
897 #endif
898
899 //----------------------------LoadNode::make-----------------------------------
900 // Polymorphic factory method:
901 Node *LoadNode::make(PhaseGVN& gvn, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt, MemOrd mo) {
902 Compile* C = gvn.C;
903
904 // sanity check the alias category against the created node type
905 assert(!(adr_type->isa_oopptr() &&
906 adr_type->offset() == oopDesc::klass_offset_in_bytes()),
907 "use LoadKlassNode instead");
908 assert(!(adr_type->isa_aryptr() &&
909 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
910 "use LoadRangeNode instead");
911 // Check control edge of raw loads
912 assert( ctl != NULL || C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
913 // oop will be recorded in oop map if load crosses safepoint
914 rt->isa_oopptr() || is_immutable_value(adr),
915 "raw memory operations should have control edge");
916 switch (bt) {
917 case T_BOOLEAN: return new LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(), mo);
918 case T_BYTE: return new LoadBNode (ctl, mem, adr, adr_type, rt->is_int(), mo);
919 case T_INT: return new LoadINode (ctl, mem, adr, adr_type, rt->is_int(), mo);
920 case T_CHAR: return new LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(), mo);
921 case T_SHORT: return new LoadSNode (ctl, mem, adr, adr_type, rt->is_int(), mo);
922 case T_LONG: return new LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo);
923 case T_FLOAT: return new LoadFNode (ctl, mem, adr, adr_type, rt, mo);
924 case T_DOUBLE: return new LoadDNode (ctl, mem, adr, adr_type, rt, mo);
925 case T_ADDRESS: return new LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(), mo);
926 case T_OBJECT:
927 #ifdef _LP64
928 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
929 Node* load = gvn.transform(new LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo));
930 return new DecodeNNode(load, load->bottom_type()->make_ptr());
931 } else
932 #endif
933 {
934 assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop");
935 return new LoadPNode(ctl, mem, adr, adr_type, rt->is_oopptr(), mo);
936 }
937 }
938 ShouldNotReachHere();
939 return (LoadNode*)NULL;
940 }
941
942 LoadLNode* LoadLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo) {
943 bool require_atomic = true;
944 return new LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), mo, require_atomic);
945 }
946
947 LoadDNode* LoadDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo) {
948 bool require_atomic = true;
949 return new LoadDNode(ctl, mem, adr, adr_type, rt, mo, require_atomic);
950 }
951
952
953
954 //------------------------------hash-------------------------------------------
955 uint LoadNode::hash() const {
956 // unroll addition of interesting fields
957 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
958 }
959
960 static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) {
961 if ((atp != NULL) && (atp->index() >= Compile::AliasIdxRaw)) {
962 bool non_volatile = (atp->field() != NULL) && !atp->field()->is_volatile();
963 bool is_stable_ary = FoldStableValues &&
964 (tp != NULL) && (tp->isa_aryptr() != NULL) &&
965 tp->isa_aryptr()->is_stable();
966
967 return (eliminate_boxing && non_volatile) || is_stable_ary;
968 }
969
970 return false;
971 }
972
973 //---------------------------can_see_stored_value------------------------------
974 // This routine exists to make sure this set of tests is done the same
975 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
976 // will change the graph shape in a way which makes memory alive twice at the
977 // same time (uses the Oracle model of aliasing), then some
978 // LoadXNode::Identity will fold things back to the equivalence-class model
979 // of aliasing.
980 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const {
981 Node* ld_adr = in(MemNode::Address);
982 intptr_t ld_off = 0;
983 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
984 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
985 Compile::AliasType* atp = (tp != NULL) ? phase->C->alias_type(tp) : NULL;
986 // This is more general than load from boxing objects.
987 if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) {
988 uint alias_idx = atp->index();
989 bool final = !atp->is_rewritable();
990 Node* result = NULL;
991 Node* current = st;
992 // Skip through chains of MemBarNodes checking the MergeMems for
993 // new states for the slice of this load. Stop once any other
994 // kind of node is encountered. Loads from final memory can skip
995 // through any kind of MemBar but normal loads shouldn't skip
996 // through MemBarAcquire since the could allow them to move out of
997 // a synchronized region.
998 while (current->is_Proj()) {
999 int opc = current->in(0)->Opcode();
1000 if ((final && (opc == Op_MemBarAcquire ||
1001 opc == Op_MemBarAcquireLock ||
1002 opc == Op_LoadFence)) ||
1003 opc == Op_MemBarRelease ||
1004 opc == Op_StoreFence ||
1005 opc == Op_MemBarReleaseLock ||
1006 opc == Op_MemBarCPUOrder) {
1007 Node* mem = current->in(0)->in(TypeFunc::Memory);
1008 if (mem->is_MergeMem()) {
1009 MergeMemNode* merge = mem->as_MergeMem();
1010 Node* new_st = merge->memory_at(alias_idx);
1011 if (new_st == merge->base_memory()) {
1012 // Keep searching
1013 current = new_st;
1014 continue;
1015 }
1016 // Save the new memory state for the slice and fall through
1017 // to exit.
1018 result = new_st;
1019 }
1020 }
1021 break;
1022 }
1023 if (result != NULL) {
1024 st = result;
1025 }
1026 }
1027
1028 // Loop around twice in the case Load -> Initialize -> Store.
1029 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
1030 for (int trip = 0; trip <= 1; trip++) {
1031
1032 if (st->is_Store()) {
1033 Node* st_adr = st->in(MemNode::Address);
1034 if (!phase->eqv(st_adr, ld_adr)) {
1035 // Try harder before giving up... Match raw and non-raw pointers.
1036 intptr_t st_off = 0;
1037 AllocateNode* alloc = AllocateNode::Ideal_allocation(st_adr, phase, st_off);
1038 if (alloc == NULL) return NULL;
1039 if (alloc != ld_alloc) return NULL;
1040 if (ld_off != st_off) return NULL;
1041 // At this point we have proven something like this setup:
1042 // A = Allocate(...)
1043 // L = LoadQ(, AddP(CastPP(, A.Parm),, #Off))
1044 // S = StoreQ(, AddP(, A.Parm , #Off), V)
1045 // (Actually, we haven't yet proven the Q's are the same.)
1046 // In other words, we are loading from a casted version of
1047 // the same pointer-and-offset that we stored to.
1048 // Thus, we are able to replace L by V.
1049 }
1050 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
1051 if (store_Opcode() != st->Opcode())
1052 return NULL;
1053 return st->in(MemNode::ValueIn);
1054 }
1055
1056 // A load from a freshly-created object always returns zero.
1057 // (This can happen after LoadNode::Ideal resets the load's memory input
1058 // to find_captured_store, which returned InitializeNode::zero_memory.)
1059 if (st->is_Proj() && st->in(0)->is_Allocate() &&
1060 (st->in(0) == ld_alloc) &&
1061 (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) {
1062 // return a zero value for the load's basic type
1063 // (This is one of the few places where a generic PhaseTransform
1064 // can create new nodes. Think of it as lazily manifesting
1065 // virtually pre-existing constants.)
1066 return phase->zerocon(memory_type());
1067 }
1068
1069 // A load from an initialization barrier can match a captured store.
1070 if (st->is_Proj() && st->in(0)->is_Initialize()) {
1071 InitializeNode* init = st->in(0)->as_Initialize();
1072 AllocateNode* alloc = init->allocation();
1073 if ((alloc != NULL) && (alloc == ld_alloc)) {
1074 // examine a captured store value
1075 st = init->find_captured_store(ld_off, memory_size(), phase);
1076 if (st != NULL)
1077 continue; // take one more trip around
1078 }
1079 }
1080
1081 // Load boxed value from result of valueOf() call is input parameter.
1082 if (this->is_Load() && ld_adr->is_AddP() &&
1083 (tp != NULL) && tp->is_ptr_to_boxed_value()) {
1084 intptr_t ignore = 0;
1085 Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore);
1086 if (base != NULL && base->is_Proj() &&
1087 base->as_Proj()->_con == TypeFunc::Parms &&
1088 base->in(0)->is_CallStaticJava() &&
1089 base->in(0)->as_CallStaticJava()->is_boxing_method()) {
1090 return base->in(0)->in(TypeFunc::Parms);
1091 }
1092 }
1093
1094 break;
1095 }
1096
1097 return NULL;
1098 }
1099
1100 //----------------------is_instance_field_load_with_local_phi------------------
1101 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
1102 if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl &&
1103 in(Address)->is_AddP() ) {
1104 const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr();
1105 // Only instances and boxed values.
1106 if( t_oop != NULL &&
1107 (t_oop->is_ptr_to_boxed_value() ||
1108 t_oop->is_known_instance_field()) &&
1109 t_oop->offset() != Type::OffsetBot &&
1110 t_oop->offset() != Type::OffsetTop) {
1111 return true;
1112 }
1113 }
1114 return false;
1115 }
1116
1117 //------------------------------Identity---------------------------------------
1118 // Loads are identity if previous store is to same address
1119 Node *LoadNode::Identity( PhaseTransform *phase ) {
1120 // If the previous store-maker is the right kind of Store, and the store is
1121 // to the same address, then we are equal to the value stored.
1122 Node* mem = in(Memory);
1123 Node* value = can_see_stored_value(mem, phase);
1124 if( value ) {
1125 // byte, short & char stores truncate naturally.
1126 // A load has to load the truncated value which requires
1127 // some sort of masking operation and that requires an
1128 // Ideal call instead of an Identity call.
1129 if (memory_size() < BytesPerInt) {
1130 // If the input to the store does not fit with the load's result type,
1131 // it must be truncated via an Ideal call.
1132 if (!phase->type(value)->higher_equal(phase->type(this)))
1133 return this;
1134 }
1135 // (This works even when value is a Con, but LoadNode::Value
1136 // usually runs first, producing the singleton type of the Con.)
1137 return value;
1138 }
1139
1140 // Search for an existing data phi which was generated before for the same
1141 // instance's field to avoid infinite generation of phis in a loop.
1142 Node *region = mem->in(0);
1143 if (is_instance_field_load_with_local_phi(region)) {
1144 const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr();
1145 int this_index = phase->C->get_alias_index(addr_t);
1146 int this_offset = addr_t->offset();
1147 int this_iid = addr_t->instance_id();
1148 if (!addr_t->is_known_instance() &&
1149 addr_t->is_ptr_to_boxed_value()) {
1150 // Use _idx of address base (could be Phi node) for boxed values.
1151 intptr_t ignore = 0;
1152 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1153 this_iid = base->_idx;
1154 }
1155 const Type* this_type = bottom_type();
1156 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1157 Node* phi = region->fast_out(i);
1158 if (phi->is_Phi() && phi != mem &&
1159 phi->as_Phi()->is_same_inst_field(this_type, this_iid, this_index, this_offset)) {
1160 return phi;
1161 }
1162 }
1163 }
1164
1165 return this;
1166 }
1167
1168 // We're loading from an object which has autobox behaviour.
1169 // If this object is result of a valueOf call we'll have a phi
1170 // merging a newly allocated object and a load from the cache.
1171 // We want to replace this load with the original incoming
1172 // argument to the valueOf call.
1173 Node* LoadNode::eliminate_autobox(PhaseGVN* phase) {
1174 assert(phase->C->eliminate_boxing(), "sanity");
1175 intptr_t ignore = 0;
1176 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1177 if ((base == NULL) || base->is_Phi()) {
1178 // Push the loads from the phi that comes from valueOf up
1179 // through it to allow elimination of the loads and the recovery
1180 // of the original value. It is done in split_through_phi().
1181 return NULL;
1182 } else if (base->is_Load() ||
1183 base->is_DecodeN() && base->in(1)->is_Load()) {
1184 // Eliminate the load of boxed value for integer types from the cache
1185 // array by deriving the value from the index into the array.
1186 // Capture the offset of the load and then reverse the computation.
1187
1188 // Get LoadN node which loads a boxing object from 'cache' array.
1189 if (base->is_DecodeN()) {
1190 base = base->in(1);
1191 }
1192 if (!base->in(Address)->is_AddP()) {
1193 return NULL; // Complex address
1194 }
1195 AddPNode* address = base->in(Address)->as_AddP();
1196 Node* cache_base = address->in(AddPNode::Base);
1197 if ((cache_base != NULL) && cache_base->is_DecodeN()) {
1198 // Get ConP node which is static 'cache' field.
1199 cache_base = cache_base->in(1);
1200 }
1201 if ((cache_base != NULL) && cache_base->is_Con()) {
1202 const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr();
1203 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1204 Node* elements[4];
1205 int shift = exact_log2(type2aelembytes(T_OBJECT));
1206 int count = address->unpack_offsets(elements, ARRAY_SIZE(elements));
1207 if ((count > 0) && elements[0]->is_Con() &&
1208 ((count == 1) ||
1209 (count == 2) && elements[1]->Opcode() == Op_LShiftX &&
1210 elements[1]->in(2) == phase->intcon(shift))) {
1211 ciObjArray* array = base_type->const_oop()->as_obj_array();
1212 // Fetch the box object cache[0] at the base of the array and get its value
1213 ciInstance* box = array->obj_at(0)->as_instance();
1214 ciInstanceKlass* ik = box->klass()->as_instance_klass();
1215 assert(ik->is_box_klass(), "sanity");
1216 assert(ik->nof_nonstatic_fields() == 1, "change following code");
1217 if (ik->nof_nonstatic_fields() == 1) {
1218 // This should be true nonstatic_field_at requires calling
1219 // nof_nonstatic_fields so check it anyway
1220 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1221 BasicType bt = c.basic_type();
1222 // Only integer types have boxing cache.
1223 assert(bt == T_BOOLEAN || bt == T_CHAR ||
1224 bt == T_BYTE || bt == T_SHORT ||
1225 bt == T_INT || bt == T_LONG, err_msg_res("wrong type = %s", type2name(bt)));
1226 jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int();
1227 if (cache_low != (int)cache_low) {
1228 return NULL; // should not happen since cache is array indexed by value
1229 }
1230 jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift);
1231 if (offset != (int)offset) {
1232 return NULL; // should not happen since cache is array indexed by value
1233 }
1234 // Add up all the offsets making of the address of the load
1235 Node* result = elements[0];
1236 for (int i = 1; i < count; i++) {
1237 result = phase->transform(new AddXNode(result, elements[i]));
1238 }
1239 // Remove the constant offset from the address and then
1240 result = phase->transform(new AddXNode(result, phase->MakeConX(-(int)offset)));
1241 // remove the scaling of the offset to recover the original index.
1242 if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) {
1243 // Peel the shift off directly but wrap it in a dummy node
1244 // since Ideal can't return existing nodes
1245 result = new RShiftXNode(result->in(1), phase->intcon(0));
1246 } else if (result->is_Add() && result->in(2)->is_Con() &&
1247 result->in(1)->Opcode() == Op_LShiftX &&
1248 result->in(1)->in(2) == phase->intcon(shift)) {
1249 // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z)
1250 // but for boxing cache access we know that X<<Z will not overflow
1251 // (there is range check) so we do this optimizatrion by hand here.
1252 Node* add_con = new RShiftXNode(result->in(2), phase->intcon(shift));
1253 result = new AddXNode(result->in(1)->in(1), phase->transform(add_con));
1254 } else {
1255 result = new RShiftXNode(result, phase->intcon(shift));
1256 }
1257 #ifdef _LP64
1258 if (bt != T_LONG) {
1259 result = new ConvL2INode(phase->transform(result));
1260 }
1261 #else
1262 if (bt == T_LONG) {
1263 result = new ConvI2LNode(phase->transform(result));
1264 }
1265 #endif
1266 // Boxing/unboxing can be done from signed & unsigned loads (e.g. LoadUB -> ... -> LoadB pair).
1267 // Need to preserve unboxing load type if it is unsigned.
1268 switch(this->Opcode()) {
1269 case Op_LoadUB:
1270 result = new AndINode(phase->transform(result), phase->intcon(0xFF));
1271 break;
1272 case Op_LoadUS:
1273 result = new AndINode(phase->transform(result), phase->intcon(0xFFFF));
1274 break;
1275 }
1276 return result;
1277 }
1278 }
1279 }
1280 }
1281 }
1282 return NULL;
1283 }
1284
1285 static bool stable_phi(PhiNode* phi, PhaseGVN *phase) {
1286 Node* region = phi->in(0);
1287 if (region == NULL) {
1288 return false; // Wait stable graph
1289 }
1290 uint cnt = phi->req();
1291 for (uint i = 1; i < cnt; i++) {
1292 Node* rc = region->in(i);
1293 if (rc == NULL || phase->type(rc) == Type::TOP)
1294 return false; // Wait stable graph
1295 Node* in = phi->in(i);
1296 if (in == NULL || phase->type(in) == Type::TOP)
1297 return false; // Wait stable graph
1298 }
1299 return true;
1300 }
1301 //------------------------------split_through_phi------------------------------
1302 // Split instance or boxed field load through Phi.
1303 Node *LoadNode::split_through_phi(PhaseGVN *phase) {
1304 Node* mem = in(Memory);
1305 Node* address = in(Address);
1306 const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr();
1307
1308 assert((t_oop != NULL) &&
1309 (t_oop->is_known_instance_field() ||
1310 t_oop->is_ptr_to_boxed_value()), "invalide conditions");
1311
1312 Compile* C = phase->C;
1313 intptr_t ignore = 0;
1314 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1315 bool base_is_phi = (base != NULL) && base->is_Phi();
1316 bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() &&
1317 (base != NULL) && (base == address->in(AddPNode::Base)) &&
1318 phase->type(base)->higher_equal(TypePtr::NOTNULL);
1319
1320 if (!((mem->is_Phi() || base_is_phi) &&
1321 (load_boxed_values || t_oop->is_known_instance_field()))) {
1322 return NULL; // memory is not Phi
1323 }
1324
1325 if (mem->is_Phi()) {
1326 if (!stable_phi(mem->as_Phi(), phase)) {
1327 return NULL; // Wait stable graph
1328 }
1329 uint cnt = mem->req();
1330 // Check for loop invariant memory.
1331 if (cnt == 3) {
1332 for (uint i = 1; i < cnt; i++) {
1333 Node* in = mem->in(i);
1334 Node* m = optimize_memory_chain(in, t_oop, this, phase);
1335 if (m == mem) {
1336 set_req(Memory, mem->in(cnt - i));
1337 return this; // made change
1338 }
1339 }
1340 }
1341 }
1342 if (base_is_phi) {
1343 if (!stable_phi(base->as_Phi(), phase)) {
1344 return NULL; // Wait stable graph
1345 }
1346 uint cnt = base->req();
1347 // Check for loop invariant memory.
1348 if (cnt == 3) {
1349 for (uint i = 1; i < cnt; i++) {
1350 if (base->in(i) == base) {
1351 return NULL; // Wait stable graph
1352 }
1353 }
1354 }
1355 }
1356
1357 bool load_boxed_phi = load_boxed_values && base_is_phi && (base->in(0) == mem->in(0));
1358
1359 // Split through Phi (see original code in loopopts.cpp).
1360 assert(C->have_alias_type(t_oop), "instance should have alias type");
1361
1362 // Do nothing here if Identity will find a value
1363 // (to avoid infinite chain of value phis generation).
1364 if (!phase->eqv(this, this->Identity(phase)))
1365 return NULL;
1366
1367 // Select Region to split through.
1368 Node* region;
1369 if (!base_is_phi) {
1370 assert(mem->is_Phi(), "sanity");
1371 region = mem->in(0);
1372 // Skip if the region dominates some control edge of the address.
1373 if (!MemNode::all_controls_dominate(address, region))
1374 return NULL;
1375 } else if (!mem->is_Phi()) {
1376 assert(base_is_phi, "sanity");
1377 region = base->in(0);
1378 // Skip if the region dominates some control edge of the memory.
1379 if (!MemNode::all_controls_dominate(mem, region))
1380 return NULL;
1381 } else if (base->in(0) != mem->in(0)) {
1382 assert(base_is_phi && mem->is_Phi(), "sanity");
1383 if (MemNode::all_controls_dominate(mem, base->in(0))) {
1384 region = base->in(0);
1385 } else if (MemNode::all_controls_dominate(address, mem->in(0))) {
1386 region = mem->in(0);
1387 } else {
1388 return NULL; // complex graph
1389 }
1390 } else {
1391 assert(base->in(0) == mem->in(0), "sanity");
1392 region = mem->in(0);
1393 }
1394
1395 const Type* this_type = this->bottom_type();
1396 int this_index = C->get_alias_index(t_oop);
1397 int this_offset = t_oop->offset();
1398 int this_iid = t_oop->instance_id();
1399 if (!t_oop->is_known_instance() && load_boxed_values) {
1400 // Use _idx of address base for boxed values.
1401 this_iid = base->_idx;
1402 }
1403 PhaseIterGVN* igvn = phase->is_IterGVN();
1404 Node* phi = new PhiNode(region, this_type, NULL, this_iid, this_index, this_offset);
1405 for (uint i = 1; i < region->req(); i++) {
1406 Node* x;
1407 Node* the_clone = NULL;
1408 if (region->in(i) == C->top()) {
1409 x = C->top(); // Dead path? Use a dead data op
1410 } else {
1411 x = this->clone(); // Else clone up the data op
1412 the_clone = x; // Remember for possible deletion.
1413 // Alter data node to use pre-phi inputs
1414 if (this->in(0) == region) {
1415 x->set_req(0, region->in(i));
1416 } else {
1417 x->set_req(0, NULL);
1418 }
1419 if (mem->is_Phi() && (mem->in(0) == region)) {
1420 x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone.
1421 }
1422 if (address->is_Phi() && address->in(0) == region) {
1423 x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone
1424 }
1425 if (base_is_phi && (base->in(0) == region)) {
1426 Node* base_x = base->in(i); // Clone address for loads from boxed objects.
1427 Node* adr_x = phase->transform(new AddPNode(base_x,base_x,address->in(AddPNode::Offset)));
1428 x->set_req(Address, adr_x);
1429 }
1430 }
1431 // Check for a 'win' on some paths
1432 const Type *t = x->Value(igvn);
1433
1434 bool singleton = t->singleton();
1435
1436 // See comments in PhaseIdealLoop::split_thru_phi().
1437 if (singleton && t == Type::TOP) {
1438 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1439 }
1440
1441 if (singleton) {
1442 x = igvn->makecon(t);
1443 } else {
1444 // We now call Identity to try to simplify the cloned node.
1445 // Note that some Identity methods call phase->type(this).
1446 // Make sure that the type array is big enough for
1447 // our new node, even though we may throw the node away.
1448 // (This tweaking with igvn only works because x is a new node.)
1449 igvn->set_type(x, t);
1450 // If x is a TypeNode, capture any more-precise type permanently into Node
1451 // otherwise it will be not updated during igvn->transform since
1452 // igvn->type(x) is set to x->Value() already.
1453 x->raise_bottom_type(t);
1454 Node *y = x->Identity(igvn);
1455 if (y != x) {
1456 x = y;
1457 } else {
1458 y = igvn->hash_find_insert(x);
1459 if (y) {
1460 x = y;
1461 } else {
1462 // Else x is a new node we are keeping
1463 // We do not need register_new_node_with_optimizer
1464 // because set_type has already been called.
1465 igvn->_worklist.push(x);
1466 }
1467 }
1468 }
1469 if (x != the_clone && the_clone != NULL) {
1470 igvn->remove_dead_node(the_clone);
1471 }
1472 phi->set_req(i, x);
1473 }
1474 // Record Phi
1475 igvn->register_new_node_with_optimizer(phi);
1476 return phi;
1477 }
1478
1479 //------------------------------Ideal------------------------------------------
1480 // If the load is from Field memory and the pointer is non-null, it might be possible to
1481 // zero out the control input.
1482 // If the offset is constant and the base is an object allocation,
1483 // try to hook me up to the exact initializing store.
1484 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1485 Node* p = MemNode::Ideal_common(phase, can_reshape);
1486 if (p) return (p == NodeSentinel) ? NULL : p;
1487
1488 Node* ctrl = in(MemNode::Control);
1489 Node* address = in(MemNode::Address);
1490 bool progress = false;
1491
1492 // Skip up past a SafePoint control. Cannot do this for Stores because
1493 // pointer stores & cardmarks must stay on the same side of a SafePoint.
1494 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint &&
1495 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw ) {
1496 ctrl = ctrl->in(0);
1497 set_req(MemNode::Control,ctrl);
1498 progress = true;
1499 }
1500
1501 intptr_t ignore = 0;
1502 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1503 if (base != NULL
1504 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
1505 // Check for useless control edge in some common special cases
1506 if (in(MemNode::Control) != NULL
1507 && can_remove_control()
1508 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1509 && all_controls_dominate(base, phase->C->start())) {
1510 // A method-invariant, non-null address (constant or 'this' argument).
1511 set_req(MemNode::Control, NULL);
1512 progress = true;
1513 }
1514 }
1515
1516 Node* mem = in(MemNode::Memory);
1517 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1518
1519 if (can_reshape && (addr_t != NULL)) {
1520 // try to optimize our memory input
1521 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase);
1522 if (opt_mem != mem) {
1523 set_req(MemNode::Memory, opt_mem);
1524 if (phase->type( opt_mem ) == Type::TOP) return NULL;
1525 return this;
1526 }
1527 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1528 if ((t_oop != NULL) &&
1529 (t_oop->is_known_instance_field() ||
1530 t_oop->is_ptr_to_boxed_value())) {
1531 PhaseIterGVN *igvn = phase->is_IterGVN();
1532 if (igvn != NULL && igvn->_worklist.member(opt_mem)) {
1533 // Delay this transformation until memory Phi is processed.
1534 phase->is_IterGVN()->_worklist.push(this);
1535 return NULL;
1536 }
1537 // Split instance field load through Phi.
1538 Node* result = split_through_phi(phase);
1539 if (result != NULL) return result;
1540
1541 if (t_oop->is_ptr_to_boxed_value()) {
1542 Node* result = eliminate_autobox(phase);
1543 if (result != NULL) return result;
1544 }
1545 }
1546 }
1547
1548 // Check for prior store with a different base or offset; make Load
1549 // independent. Skip through any number of them. Bail out if the stores
1550 // are in an endless dead cycle and report no progress. This is a key
1551 // transform for Reflection. However, if after skipping through the Stores
1552 // we can't then fold up against a prior store do NOT do the transform as
1553 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
1554 // array memory alive twice: once for the hoisted Load and again after the
1555 // bypassed Store. This situation only works if EVERYBODY who does
1556 // anti-dependence work knows how to bypass. I.e. we need all
1557 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
1558 // the alias index stuff. So instead, peek through Stores and IFF we can
1559 // fold up, do so.
1560 Node* prev_mem = find_previous_store(phase);
1561 // Steps (a), (b): Walk past independent stores to find an exact match.
1562 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) {
1563 // (c) See if we can fold up on the spot, but don't fold up here.
1564 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
1565 // just return a prior value, which is done by Identity calls.
1566 if (can_see_stored_value(prev_mem, phase)) {
1567 // Make ready for step (d):
1568 set_req(MemNode::Memory, prev_mem);
1569 return this;
1570 }
1571 }
1572
1573 return progress ? this : NULL;
1574 }
1575
1576 // Helper to recognize certain Klass fields which are invariant across
1577 // some group of array types (e.g., int[] or all T[] where T < Object).
1578 const Type*
1579 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1580 ciKlass* klass) const {
1581 if (tkls->offset() == in_bytes(Klass::modifier_flags_offset())) {
1582 // The field is Klass::_modifier_flags. Return its (constant) value.
1583 // (Folds up the 2nd indirection in aClassConstant.getModifiers().)
1584 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags");
1585 return TypeInt::make(klass->modifier_flags());
1586 }
1587 if (tkls->offset() == in_bytes(Klass::access_flags_offset())) {
1588 // The field is Klass::_access_flags. Return its (constant) value.
1589 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1590 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags");
1591 return TypeInt::make(klass->access_flags());
1592 }
1593 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) {
1594 // The field is Klass::_layout_helper. Return its constant value if known.
1595 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper");
1596 return TypeInt::make(klass->layout_helper());
1597 }
1598
1599 // No match.
1600 return NULL;
1601 }
1602
1603 // Try to constant-fold a stable array element.
1604 static const Type* fold_stable_ary_elem(const TypeAryPtr* ary, int off, BasicType loadbt) {
1605 assert(ary->const_oop(), "array should be constant");
1606 assert(ary->is_stable(), "array should be stable");
1607
1608 // Decode the results of GraphKit::array_element_address.
1609 ciArray* aobj = ary->const_oop()->as_array();
1610 ciConstant con = aobj->element_value_by_offset(off);
1611
1612 if (con.basic_type() != T_ILLEGAL && !con.is_null_or_zero()) {
1613 const Type* con_type = Type::make_from_constant(con);
1614 if (con_type != NULL) {
1615 if (con_type->isa_aryptr()) {
1616 // Join with the array element type, in case it is also stable.
1617 int dim = ary->stable_dimension();
1618 con_type = con_type->is_aryptr()->cast_to_stable(true, dim-1);
1619 }
1620 if (loadbt == T_NARROWOOP && con_type->isa_oopptr()) {
1621 con_type = con_type->make_narrowoop();
1622 }
1623 #ifndef PRODUCT
1624 if (TraceIterativeGVN) {
1625 tty->print("FoldStableValues: array element [off=%d]: con_type=", off);
1626 con_type->dump(); tty->cr();
1627 }
1628 #endif //PRODUCT
1629 return con_type;
1630 }
1631 }
1632 return NULL;
1633 }
1634
1635 //------------------------------Value-----------------------------------------
1636 const Type *LoadNode::Value( PhaseTransform *phase ) const {
1637 // Either input is TOP ==> the result is TOP
1638 Node* mem = in(MemNode::Memory);
1639 const Type *t1 = phase->type(mem);
1640 if (t1 == Type::TOP) return Type::TOP;
1641 Node* adr = in(MemNode::Address);
1642 const TypePtr* tp = phase->type(adr)->isa_ptr();
1643 if (tp == NULL || tp->empty()) return Type::TOP;
1644 int off = tp->offset();
1645 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
1646 Compile* C = phase->C;
1647
1648 // Try to guess loaded type from pointer type
1649 if (tp->isa_aryptr()) {
1650 const TypeAryPtr* ary = tp->is_aryptr();
1651 const Type* t = ary->elem();
1652
1653 // Determine whether the reference is beyond the header or not, by comparing
1654 // the offset against the offset of the start of the array's data.
1655 // Different array types begin at slightly different offsets (12 vs. 16).
1656 // We choose T_BYTE as an example base type that is least restrictive
1657 // as to alignment, which will therefore produce the smallest
1658 // possible base offset.
1659 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
1660 const bool off_beyond_header = ((uint)off >= (uint)min_base_off);
1661
1662 // Try to constant-fold a stable array element.
1663 if (FoldStableValues && ary->is_stable() && ary->const_oop() != NULL) {
1664 // Make sure the reference is not into the header and the offset is constant
1665 if (off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) {
1666 const Type* con_type = fold_stable_ary_elem(ary, off, memory_type());
1667 if (con_type != NULL) {
1668 return con_type;
1669 }
1670 }
1671 }
1672
1673 // Don't do this for integer types. There is only potential profit if
1674 // the element type t is lower than _type; that is, for int types, if _type is
1675 // more restrictive than t. This only happens here if one is short and the other
1676 // char (both 16 bits), and in those cases we've made an intentional decision
1677 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
1678 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
1679 //
1680 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
1681 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
1682 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
1683 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
1684 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
1685 // In fact, that could have been the original type of p1, and p1 could have
1686 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
1687 // expression (LShiftL quux 3) independently optimized to the constant 8.
1688 if ((t->isa_int() == NULL) && (t->isa_long() == NULL)
1689 && (_type->isa_vect() == NULL)
1690 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
1691 // t might actually be lower than _type, if _type is a unique
1692 // concrete subclass of abstract class t.
1693 if (off_beyond_header) { // is the offset beyond the header?
1694 const Type* jt = t->join_speculative(_type);
1695 // In any case, do not allow the join, per se, to empty out the type.
1696 if (jt->empty() && !t->empty()) {
1697 // This can happen if a interface-typed array narrows to a class type.
1698 jt = _type;
1699 }
1700 #ifdef ASSERT
1701 if (phase->C->eliminate_boxing() && adr->is_AddP()) {
1702 // The pointers in the autobox arrays are always non-null
1703 Node* base = adr->in(AddPNode::Base);
1704 if ((base != NULL) && base->is_DecodeN()) {
1705 // Get LoadN node which loads IntegerCache.cache field
1706 base = base->in(1);
1707 }
1708 if ((base != NULL) && base->is_Con()) {
1709 const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr();
1710 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1711 // It could be narrow oop
1712 assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity");
1713 }
1714 }
1715 }
1716 #endif
1717 return jt;
1718 }
1719 }
1720 } else if (tp->base() == Type::InstPtr) {
1721 ciEnv* env = C->env();
1722 const TypeInstPtr* tinst = tp->is_instptr();
1723 ciKlass* klass = tinst->klass();
1724 assert( off != Type::OffsetBot ||
1725 // arrays can be cast to Objects
1726 tp->is_oopptr()->klass()->is_java_lang_Object() ||
1727 // unsafe field access may not have a constant offset
1728 C->has_unsafe_access(),
1729 "Field accesses must be precise" );
1730 // For oop loads, we expect the _type to be precise
1731 if (klass == env->String_klass() &&
1732 adr->is_AddP() && off != Type::OffsetBot) {
1733 // For constant Strings treat the final fields as compile time constants.
1734 Node* base = adr->in(AddPNode::Base);
1735 const TypeOopPtr* t = phase->type(base)->isa_oopptr();
1736 if (t != NULL && t->singleton()) {
1737 ciField* field = env->String_klass()->get_field_by_offset(off, false);
1738 if (field != NULL && field->is_final()) {
1739 ciObject* string = t->const_oop();
1740 ciConstant constant = string->as_instance()->field_value(field);
1741 if (constant.basic_type() == T_INT) {
1742 return TypeInt::make(constant.as_int());
1743 } else if (constant.basic_type() == T_ARRAY) {
1744 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
1745 return TypeNarrowOop::make_from_constant(constant.as_object(), true);
1746 } else {
1747 return TypeOopPtr::make_from_constant(constant.as_object(), true);
1748 }
1749 }
1750 }
1751 }
1752 }
1753 // Optimizations for constant objects
1754 ciObject* const_oop = tinst->const_oop();
1755 if (const_oop != NULL) {
1756 // For constant Boxed value treat the target field as a compile time constant.
1757 if (tinst->is_ptr_to_boxed_value()) {
1758 return tinst->get_const_boxed_value();
1759 } else
1760 // For constant CallSites treat the target field as a compile time constant.
1761 if (const_oop->is_call_site()) {
1762 ciCallSite* call_site = const_oop->as_call_site();
1763 ciField* field = call_site->klass()->as_instance_klass()->get_field_by_offset(off, /*is_static=*/ false);
1764 if (field != NULL && field->is_call_site_target()) {
1765 ciMethodHandle* target = call_site->get_target();
1766 if (target != NULL) { // just in case
1767 ciConstant constant(T_OBJECT, target);
1768 const Type* t;
1769 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
1770 t = TypeNarrowOop::make_from_constant(constant.as_object(), true);
1771 } else {
1772 t = TypeOopPtr::make_from_constant(constant.as_object(), true);
1773 }
1774 // Add a dependence for invalidation of the optimization.
1775 if (!call_site->is_constant_call_site()) {
1776 C->dependencies()->assert_call_site_target_value(call_site, target);
1777 }
1778 return t;
1779 }
1780 }
1781 }
1782 }
1783 } else if (tp->base() == Type::KlassPtr) {
1784 assert( off != Type::OffsetBot ||
1785 // arrays can be cast to Objects
1786 tp->is_klassptr()->klass()->is_java_lang_Object() ||
1787 // also allow array-loading from the primary supertype
1788 // array during subtype checks
1789 Opcode() == Op_LoadKlass,
1790 "Field accesses must be precise" );
1791 // For klass/static loads, we expect the _type to be precise
1792 }
1793
1794 const TypeKlassPtr *tkls = tp->isa_klassptr();
1795 if (tkls != NULL && !StressReflectiveCode) {
1796 ciKlass* klass = tkls->klass();
1797 if (klass->is_loaded() && tkls->klass_is_exact()) {
1798 // We are loading a field from a Klass metaobject whose identity
1799 // is known at compile time (the type is "exact" or "precise").
1800 // Check for fields we know are maintained as constants by the VM.
1801 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) {
1802 // The field is Klass::_super_check_offset. Return its (constant) value.
1803 // (Folds up type checking code.)
1804 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
1805 return TypeInt::make(klass->super_check_offset());
1806 }
1807 // Compute index into primary_supers array
1808 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1809 // Check for overflowing; use unsigned compare to handle the negative case.
1810 if( depth < ciKlass::primary_super_limit() ) {
1811 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1812 // (Folds up type checking code.)
1813 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1814 ciKlass *ss = klass->super_of_depth(depth);
1815 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1816 }
1817 const Type* aift = load_array_final_field(tkls, klass);
1818 if (aift != NULL) return aift;
1819 if (tkls->offset() == in_bytes(Klass::java_mirror_offset())) {
1820 // The field is Klass::_java_mirror. Return its (constant) value.
1821 // (Folds up the 2nd indirection in anObjConstant.getClass().)
1822 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
1823 return TypeInstPtr::make(klass->java_mirror());
1824 }
1825 }
1826
1827 // We can still check if we are loading from the primary_supers array at a
1828 // shallow enough depth. Even though the klass is not exact, entries less
1829 // than or equal to its super depth are correct.
1830 if (klass->is_loaded() ) {
1831 ciType *inner = klass;
1832 while( inner->is_obj_array_klass() )
1833 inner = inner->as_obj_array_klass()->base_element_type();
1834 if( inner->is_instance_klass() &&
1835 !inner->as_instance_klass()->flags().is_interface() ) {
1836 // Compute index into primary_supers array
1837 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1838 // Check for overflowing; use unsigned compare to handle the negative case.
1839 if( depth < ciKlass::primary_super_limit() &&
1840 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case
1841 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1842 // (Folds up type checking code.)
1843 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1844 ciKlass *ss = klass->super_of_depth(depth);
1845 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1846 }
1847 }
1848 }
1849
1850 // If the type is enough to determine that the thing is not an array,
1851 // we can give the layout_helper a positive interval type.
1852 // This will help short-circuit some reflective code.
1853 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())
1854 && !klass->is_array_klass() // not directly typed as an array
1855 && !klass->is_interface() // specifically not Serializable & Cloneable
1856 && !klass->is_java_lang_Object() // not the supertype of all T[]
1857 ) {
1858 // Note: When interfaces are reliable, we can narrow the interface
1859 // test to (klass != Serializable && klass != Cloneable).
1860 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
1861 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
1862 // The key property of this type is that it folds up tests
1863 // for array-ness, since it proves that the layout_helper is positive.
1864 // Thus, a generic value like the basic object layout helper works fine.
1865 return TypeInt::make(min_size, max_jint, Type::WidenMin);
1866 }
1867 }
1868
1869 // If we are loading from a freshly-allocated object, produce a zero,
1870 // if the load is provably beyond the header of the object.
1871 // (Also allow a variable load from a fresh array to produce zero.)
1872 const TypeOopPtr *tinst = tp->isa_oopptr();
1873 bool is_instance = (tinst != NULL) && tinst->is_known_instance_field();
1874 bool is_boxed_value = (tinst != NULL) && tinst->is_ptr_to_boxed_value();
1875 if (ReduceFieldZeroing || is_instance || is_boxed_value) {
1876 Node* value = can_see_stored_value(mem,phase);
1877 if (value != NULL && value->is_Con()) {
1878 assert(value->bottom_type()->higher_equal(_type),"sanity");
1879 return value->bottom_type();
1880 }
1881 }
1882
1883 if (is_instance) {
1884 // If we have an instance type and our memory input is the
1885 // programs's initial memory state, there is no matching store,
1886 // so just return a zero of the appropriate type
1887 Node *mem = in(MemNode::Memory);
1888 if (mem->is_Parm() && mem->in(0)->is_Start()) {
1889 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
1890 return Type::get_zero_type(_type->basic_type());
1891 }
1892 }
1893 return _type;
1894 }
1895
1896 //------------------------------match_edge-------------------------------------
1897 // Do we Match on this edge index or not? Match only the address.
1898 uint LoadNode::match_edge(uint idx) const {
1899 return idx == MemNode::Address;
1900 }
1901
1902 //--------------------------LoadBNode::Ideal--------------------------------------
1903 //
1904 // If the previous store is to the same address as this load,
1905 // and the value stored was larger than a byte, replace this load
1906 // with the value stored truncated to a byte. If no truncation is
1907 // needed, the replacement is done in LoadNode::Identity().
1908 //
1909 Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1910 Node* mem = in(MemNode::Memory);
1911 Node* value = can_see_stored_value(mem,phase);
1912 if( value && !phase->type(value)->higher_equal( _type ) ) {
1913 Node *result = phase->transform( new LShiftINode(value, phase->intcon(24)) );
1914 return new RShiftINode(result, phase->intcon(24));
1915 }
1916 // Identity call will handle the case where truncation is not needed.
1917 return LoadNode::Ideal(phase, can_reshape);
1918 }
1919
1920 const Type* LoadBNode::Value(PhaseTransform *phase) const {
1921 Node* mem = in(MemNode::Memory);
1922 Node* value = can_see_stored_value(mem,phase);
1923 if (value != NULL && value->is_Con() &&
1924 !value->bottom_type()->higher_equal(_type)) {
1925 // If the input to the store does not fit with the load's result type,
1926 // it must be truncated. We can't delay until Ideal call since
1927 // a singleton Value is needed for split_thru_phi optimization.
1928 int con = value->get_int();
1929 return TypeInt::make((con << 24) >> 24);
1930 }
1931 return LoadNode::Value(phase);
1932 }
1933
1934 //--------------------------LoadUBNode::Ideal-------------------------------------
1935 //
1936 // If the previous store is to the same address as this load,
1937 // and the value stored was larger than a byte, replace this load
1938 // with the value stored truncated to a byte. If no truncation is
1939 // needed, the replacement is done in LoadNode::Identity().
1940 //
1941 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
1942 Node* mem = in(MemNode::Memory);
1943 Node* value = can_see_stored_value(mem, phase);
1944 if (value && !phase->type(value)->higher_equal(_type))
1945 return new AndINode(value, phase->intcon(0xFF));
1946 // Identity call will handle the case where truncation is not needed.
1947 return LoadNode::Ideal(phase, can_reshape);
1948 }
1949
1950 const Type* LoadUBNode::Value(PhaseTransform *phase) const {
1951 Node* mem = in(MemNode::Memory);
1952 Node* value = can_see_stored_value(mem,phase);
1953 if (value != NULL && value->is_Con() &&
1954 !value->bottom_type()->higher_equal(_type)) {
1955 // If the input to the store does not fit with the load's result type,
1956 // it must be truncated. We can't delay until Ideal call since
1957 // a singleton Value is needed for split_thru_phi optimization.
1958 int con = value->get_int();
1959 return TypeInt::make(con & 0xFF);
1960 }
1961 return LoadNode::Value(phase);
1962 }
1963
1964 //--------------------------LoadUSNode::Ideal-------------------------------------
1965 //
1966 // If the previous store is to the same address as this load,
1967 // and the value stored was larger than a char, replace this load
1968 // with the value stored truncated to a char. If no truncation is
1969 // needed, the replacement is done in LoadNode::Identity().
1970 //
1971 Node *LoadUSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1972 Node* mem = in(MemNode::Memory);
1973 Node* value = can_see_stored_value(mem,phase);
1974 if( value && !phase->type(value)->higher_equal( _type ) )
1975 return new AndINode(value,phase->intcon(0xFFFF));
1976 // Identity call will handle the case where truncation is not needed.
1977 return LoadNode::Ideal(phase, can_reshape);
1978 }
1979
1980 const Type* LoadUSNode::Value(PhaseTransform *phase) const {
1981 Node* mem = in(MemNode::Memory);
1982 Node* value = can_see_stored_value(mem,phase);
1983 if (value != NULL && value->is_Con() &&
1984 !value->bottom_type()->higher_equal(_type)) {
1985 // If the input to the store does not fit with the load's result type,
1986 // it must be truncated. We can't delay until Ideal call since
1987 // a singleton Value is needed for split_thru_phi optimization.
1988 int con = value->get_int();
1989 return TypeInt::make(con & 0xFFFF);
1990 }
1991 return LoadNode::Value(phase);
1992 }
1993
1994 //--------------------------LoadSNode::Ideal--------------------------------------
1995 //
1996 // If the previous store is to the same address as this load,
1997 // and the value stored was larger than a short, replace this load
1998 // with the value stored truncated to a short. If no truncation is
1999 // needed, the replacement is done in LoadNode::Identity().
2000 //
2001 Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2002 Node* mem = in(MemNode::Memory);
2003 Node* value = can_see_stored_value(mem,phase);
2004 if( value && !phase->type(value)->higher_equal( _type ) ) {
2005 Node *result = phase->transform( new LShiftINode(value, phase->intcon(16)) );
2006 return new RShiftINode(result, phase->intcon(16));
2007 }
2008 // Identity call will handle the case where truncation is not needed.
2009 return LoadNode::Ideal(phase, can_reshape);
2010 }
2011
2012 const Type* LoadSNode::Value(PhaseTransform *phase) const {
2013 Node* mem = in(MemNode::Memory);
2014 Node* value = can_see_stored_value(mem,phase);
2015 if (value != NULL && value->is_Con() &&
2016 !value->bottom_type()->higher_equal(_type)) {
2017 // If the input to the store does not fit with the load's result type,
2018 // it must be truncated. We can't delay until Ideal call since
2019 // a singleton Value is needed for split_thru_phi optimization.
2020 int con = value->get_int();
2021 return TypeInt::make((con << 16) >> 16);
2022 }
2023 return LoadNode::Value(phase);
2024 }
2025
2026 //=============================================================================
2027 //----------------------------LoadKlassNode::make------------------------------
2028 // Polymorphic factory method:
2029 Node* LoadKlassNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* at, const TypeKlassPtr* tk) {
2030 // sanity check the alias category against the created node type
2031 const TypePtr *adr_type = adr->bottom_type()->isa_ptr();
2032 assert(adr_type != NULL, "expecting TypeKlassPtr");
2033 #ifdef _LP64
2034 if (adr_type->is_ptr_to_narrowklass()) {
2035 assert(UseCompressedClassPointers, "no compressed klasses");
2036 Node* load_klass = gvn.transform(new LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowklass(), MemNode::unordered));
2037 return new DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr());
2038 }
2039 #endif
2040 assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
2041 return new LoadKlassNode(ctl, mem, adr, at, tk, MemNode::unordered);
2042 }
2043
2044 //------------------------------Value------------------------------------------
2045 const Type *LoadKlassNode::Value( PhaseTransform *phase ) const {
2046 return klass_value_common(phase);
2047 }
2048
2049 // In most cases, LoadKlassNode does not have the control input set. If the control
2050 // input is set, it must not be removed (by LoadNode::Ideal()).
2051 bool LoadKlassNode::can_remove_control() const {
2052 return false;
2053 }
2054
2055 const Type *LoadNode::klass_value_common( PhaseTransform *phase ) const {
2056 // Either input is TOP ==> the result is TOP
2057 const Type *t1 = phase->type( in(MemNode::Memory) );
2058 if (t1 == Type::TOP) return Type::TOP;
2059 Node *adr = in(MemNode::Address);
2060 const Type *t2 = phase->type( adr );
2061 if (t2 == Type::TOP) return Type::TOP;
2062 const TypePtr *tp = t2->is_ptr();
2063 if (TypePtr::above_centerline(tp->ptr()) ||
2064 tp->ptr() == TypePtr::Null) return Type::TOP;
2065
2066 // Return a more precise klass, if possible
2067 const TypeInstPtr *tinst = tp->isa_instptr();
2068 if (tinst != NULL) {
2069 ciInstanceKlass* ik = tinst->klass()->as_instance_klass();
2070 int offset = tinst->offset();
2071 if (ik == phase->C->env()->Class_klass()
2072 && (offset == java_lang_Class::klass_offset_in_bytes() ||
2073 offset == java_lang_Class::array_klass_offset_in_bytes())) {
2074 // We are loading a special hidden field from a Class mirror object,
2075 // the field which points to the VM's Klass metaobject.
2076 ciType* t = tinst->java_mirror_type();
2077 // java_mirror_type returns non-null for compile-time Class constants.
2078 if (t != NULL) {
2079 // constant oop => constant klass
2080 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
2081 if (t->is_void()) {
2082 // We cannot create a void array. Since void is a primitive type return null
2083 // klass. Users of this result need to do a null check on the returned klass.
2084 return TypePtr::NULL_PTR;
2085 }
2086 return TypeKlassPtr::make(ciArrayKlass::make(t));
2087 }
2088 if (!t->is_klass()) {
2089 // a primitive Class (e.g., int.class) has NULL for a klass field
2090 return TypePtr::NULL_PTR;
2091 }
2092 // (Folds up the 1st indirection in aClassConstant.getModifiers().)
2093 return TypeKlassPtr::make(t->as_klass());
2094 }
2095 // non-constant mirror, so we can't tell what's going on
2096 }
2097 if( !ik->is_loaded() )
2098 return _type; // Bail out if not loaded
2099 if (offset == oopDesc::klass_offset_in_bytes()) {
2100 if (tinst->klass_is_exact()) {
2101 return TypeKlassPtr::make(ik);
2102 }
2103 // See if we can become precise: no subklasses and no interface
2104 // (Note: We need to support verified interfaces.)
2105 if (!ik->is_interface() && !ik->has_subklass()) {
2106 //assert(!UseExactTypes, "this code should be useless with exact types");
2107 // Add a dependence; if any subclass added we need to recompile
2108 if (!ik->is_final()) {
2109 // %%% should use stronger assert_unique_concrete_subtype instead
2110 phase->C->dependencies()->assert_leaf_type(ik);
2111 }
2112 // Return precise klass
2113 return TypeKlassPtr::make(ik);
2114 }
2115
2116 // Return root of possible klass
2117 return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/);
2118 }
2119 }
2120
2121 // Check for loading klass from an array
2122 const TypeAryPtr *tary = tp->isa_aryptr();
2123 if( tary != NULL ) {
2124 ciKlass *tary_klass = tary->klass();
2125 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP
2126 && tary->offset() == oopDesc::klass_offset_in_bytes()) {
2127 if (tary->klass_is_exact()) {
2128 return TypeKlassPtr::make(tary_klass);
2129 }
2130 ciArrayKlass *ak = tary->klass()->as_array_klass();
2131 // If the klass is an object array, we defer the question to the
2132 // array component klass.
2133 if( ak->is_obj_array_klass() ) {
2134 assert( ak->is_loaded(), "" );
2135 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass();
2136 if( base_k->is_loaded() && base_k->is_instance_klass() ) {
2137 ciInstanceKlass* ik = base_k->as_instance_klass();
2138 // See if we can become precise: no subklasses and no interface
2139 if (!ik->is_interface() && !ik->has_subklass()) {
2140 //assert(!UseExactTypes, "this code should be useless with exact types");
2141 // Add a dependence; if any subclass added we need to recompile
2142 if (!ik->is_final()) {
2143 phase->C->dependencies()->assert_leaf_type(ik);
2144 }
2145 // Return precise array klass
2146 return TypeKlassPtr::make(ak);
2147 }
2148 }
2149 return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/);
2150 } else { // Found a type-array?
2151 //assert(!UseExactTypes, "this code should be useless with exact types");
2152 assert( ak->is_type_array_klass(), "" );
2153 return TypeKlassPtr::make(ak); // These are always precise
2154 }
2155 }
2156 }
2157
2158 // Check for loading klass from an array klass
2159 const TypeKlassPtr *tkls = tp->isa_klassptr();
2160 if (tkls != NULL && !StressReflectiveCode) {
2161 ciKlass* klass = tkls->klass();
2162 if( !klass->is_loaded() )
2163 return _type; // Bail out if not loaded
2164 if( klass->is_obj_array_klass() &&
2165 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) {
2166 ciKlass* elem = klass->as_obj_array_klass()->element_klass();
2167 // // Always returning precise element type is incorrect,
2168 // // e.g., element type could be object and array may contain strings
2169 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
2170
2171 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
2172 // according to the element type's subclassing.
2173 return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/);
2174 }
2175 if( klass->is_instance_klass() && tkls->klass_is_exact() &&
2176 tkls->offset() == in_bytes(Klass::super_offset())) {
2177 ciKlass* sup = klass->as_instance_klass()->super();
2178 // The field is Klass::_super. Return its (constant) value.
2179 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
2180 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR;
2181 }
2182 }
2183
2184 // Bailout case
2185 return LoadNode::Value(phase);
2186 }
2187
2188 //------------------------------Identity---------------------------------------
2189 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
2190 // Also feed through the klass in Allocate(...klass...)._klass.
2191 Node* LoadKlassNode::Identity( PhaseTransform *phase ) {
2192 return klass_identity_common(phase);
2193 }
2194
2195 Node* LoadNode::klass_identity_common(PhaseTransform *phase ) {
2196 Node* x = LoadNode::Identity(phase);
2197 if (x != this) return x;
2198
2199 // Take apart the address into an oop and and offset.
2200 // Return 'this' if we cannot.
2201 Node* adr = in(MemNode::Address);
2202 intptr_t offset = 0;
2203 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2204 if (base == NULL) return this;
2205 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
2206 if (toop == NULL) return this;
2207
2208 // We can fetch the klass directly through an AllocateNode.
2209 // This works even if the klass is not constant (clone or newArray).
2210 if (offset == oopDesc::klass_offset_in_bytes()) {
2211 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
2212 if (allocated_klass != NULL) {
2213 return allocated_klass;
2214 }
2215 }
2216
2217 // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*.
2218 // See inline_native_Class_query for occurrences of these patterns.
2219 // Java Example: x.getClass().isAssignableFrom(y)
2220 //
2221 // This improves reflective code, often making the Class
2222 // mirror go completely dead. (Current exception: Class
2223 // mirrors may appear in debug info, but we could clean them out by
2224 // introducing a new debug info operator for Klass*.java_mirror).
2225 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass()
2226 && offset == java_lang_Class::klass_offset_in_bytes()) {
2227 // We are loading a special hidden field from a Class mirror,
2228 // the field which points to its Klass or ArrayKlass metaobject.
2229 if (base->is_Load()) {
2230 Node* adr2 = base->in(MemNode::Address);
2231 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2232 if (tkls != NULL && !tkls->empty()
2233 && (tkls->klass()->is_instance_klass() ||
2234 tkls->klass()->is_array_klass())
2235 && adr2->is_AddP()
2236 ) {
2237 int mirror_field = in_bytes(Klass::java_mirror_offset());
2238 if (tkls->offset() == mirror_field) {
2239 return adr2->in(AddPNode::Base);
2240 }
2241 }
2242 }
2243 }
2244
2245 return this;
2246 }
2247
2248
2249 //------------------------------Value------------------------------------------
2250 const Type *LoadNKlassNode::Value( PhaseTransform *phase ) const {
2251 const Type *t = klass_value_common(phase);
2252 if (t == Type::TOP)
2253 return t;
2254
2255 return t->make_narrowklass();
2256 }
2257
2258 //------------------------------Identity---------------------------------------
2259 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
2260 // Also feed through the klass in Allocate(...klass...)._klass.
2261 Node* LoadNKlassNode::Identity( PhaseTransform *phase ) {
2262 Node *x = klass_identity_common(phase);
2263
2264 const Type *t = phase->type( x );
2265 if( t == Type::TOP ) return x;
2266 if( t->isa_narrowklass()) return x;
2267 assert (!t->isa_narrowoop(), "no narrow oop here");
2268
2269 return phase->transform(new EncodePKlassNode(x, t->make_narrowklass()));
2270 }
2271
2272 //------------------------------Value-----------------------------------------
2273 const Type *LoadRangeNode::Value( PhaseTransform *phase ) const {
2274 // Either input is TOP ==> the result is TOP
2275 const Type *t1 = phase->type( in(MemNode::Memory) );
2276 if( t1 == Type::TOP ) return Type::TOP;
2277 Node *adr = in(MemNode::Address);
2278 const Type *t2 = phase->type( adr );
2279 if( t2 == Type::TOP ) return Type::TOP;
2280 const TypePtr *tp = t2->is_ptr();
2281 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
2282 const TypeAryPtr *tap = tp->isa_aryptr();
2283 if( !tap ) return _type;
2284 return tap->size();
2285 }
2286
2287 //-------------------------------Ideal---------------------------------------
2288 // Feed through the length in AllocateArray(...length...)._length.
2289 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2290 Node* p = MemNode::Ideal_common(phase, can_reshape);
2291 if (p) return (p == NodeSentinel) ? NULL : p;
2292
2293 // Take apart the address into an oop and and offset.
2294 // Return 'this' if we cannot.
2295 Node* adr = in(MemNode::Address);
2296 intptr_t offset = 0;
2297 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2298 if (base == NULL) return NULL;
2299 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2300 if (tary == NULL) return NULL;
2301
2302 // We can fetch the length directly through an AllocateArrayNode.
2303 // This works even if the length is not constant (clone or newArray).
2304 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2305 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2306 if (alloc != NULL) {
2307 Node* allocated_length = alloc->Ideal_length();
2308 Node* len = alloc->make_ideal_length(tary, phase);
2309 if (allocated_length != len) {
2310 // New CastII improves on this.
2311 return len;
2312 }
2313 }
2314 }
2315
2316 return NULL;
2317 }
2318
2319 //------------------------------Identity---------------------------------------
2320 // Feed through the length in AllocateArray(...length...)._length.
2321 Node* LoadRangeNode::Identity( PhaseTransform *phase ) {
2322 Node* x = LoadINode::Identity(phase);
2323 if (x != this) return x;
2324
2325 // Take apart the address into an oop and and offset.
2326 // Return 'this' if we cannot.
2327 Node* adr = in(MemNode::Address);
2328 intptr_t offset = 0;
2329 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2330 if (base == NULL) return this;
2331 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2332 if (tary == NULL) return this;
2333
2334 // We can fetch the length directly through an AllocateArrayNode.
2335 // This works even if the length is not constant (clone or newArray).
2336 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2337 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2338 if (alloc != NULL) {
2339 Node* allocated_length = alloc->Ideal_length();
2340 // Do not allow make_ideal_length to allocate a CastII node.
2341 Node* len = alloc->make_ideal_length(tary, phase, false);
2342 if (allocated_length == len) {
2343 // Return allocated_length only if it would not be improved by a CastII.
2344 return allocated_length;
2345 }
2346 }
2347 }
2348
2349 return this;
2350
2351 }
2352
2353 //=============================================================================
2354 //---------------------------StoreNode::make-----------------------------------
2355 // Polymorphic factory method:
2356 StoreNode* StoreNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt, MemOrd mo) {
2357 assert((mo == unordered || mo == release), "unexpected");
2358 Compile* C = gvn.C;
2359 assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2360 ctl != NULL, "raw memory operations should have control edge");
2361
2362 switch (bt) {
2363 case T_BOOLEAN:
2364 case T_BYTE: return new StoreBNode(ctl, mem, adr, adr_type, val, mo);
2365 case T_INT: return new StoreINode(ctl, mem, adr, adr_type, val, mo);
2366 case T_CHAR:
2367 case T_SHORT: return new StoreCNode(ctl, mem, adr, adr_type, val, mo);
2368 case T_LONG: return new StoreLNode(ctl, mem, adr, adr_type, val, mo);
2369 case T_FLOAT: return new StoreFNode(ctl, mem, adr, adr_type, val, mo);
2370 case T_DOUBLE: return new StoreDNode(ctl, mem, adr, adr_type, val, mo);
2371 case T_METADATA:
2372 case T_ADDRESS:
2373 case T_OBJECT:
2374 #ifdef _LP64
2375 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
2376 val = gvn.transform(new EncodePNode(val, val->bottom_type()->make_narrowoop()));
2377 return new StoreNNode(ctl, mem, adr, adr_type, val, mo);
2378 } else if (adr->bottom_type()->is_ptr_to_narrowklass() ||
2379 (UseCompressedClassPointers && val->bottom_type()->isa_klassptr() &&
2380 adr->bottom_type()->isa_rawptr())) {
2381 val = gvn.transform(new EncodePKlassNode(val, val->bottom_type()->make_narrowklass()));
2382 return new StoreNKlassNode(ctl, mem, adr, adr_type, val, mo);
2383 }
2384 #endif
2385 {
2386 return new StorePNode(ctl, mem, adr, adr_type, val, mo);
2387 }
2388 }
2389 ShouldNotReachHere();
2390 return (StoreNode*)NULL;
2391 }
2392
2393 StoreLNode* StoreLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
2394 bool require_atomic = true;
2395 return new StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
2396 }
2397
2398 StoreDNode* StoreDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
2399 bool require_atomic = true;
2400 return new StoreDNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
2401 }
2402
2403
2404 //--------------------------bottom_type----------------------------------------
2405 const Type *StoreNode::bottom_type() const {
2406 return Type::MEMORY;
2407 }
2408
2409 //------------------------------hash-------------------------------------------
2410 uint StoreNode::hash() const {
2411 // unroll addition of interesting fields
2412 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2413
2414 // Since they are not commoned, do not hash them:
2415 return NO_HASH;
2416 }
2417
2418 //------------------------------Ideal------------------------------------------
2419 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
2420 // When a store immediately follows a relevant allocation/initialization,
2421 // try to capture it into the initialization, or hoist it above.
2422 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2423 Node* p = MemNode::Ideal_common(phase, can_reshape);
2424 if (p) return (p == NodeSentinel) ? NULL : p;
2425
2426 Node* mem = in(MemNode::Memory);
2427 Node* address = in(MemNode::Address);
2428
2429 // Back-to-back stores to same address? Fold em up. Generally
2430 // unsafe if I have intervening uses... Also disallowed for StoreCM
2431 // since they must follow each StoreP operation. Redundant StoreCMs
2432 // are eliminated just before matching in final_graph_reshape.
2433 if (mem->is_Store() && mem->in(MemNode::Address)->eqv_uncast(address) &&
2434 mem->Opcode() != Op_StoreCM) {
2435 // Looking at a dead closed cycle of memory?
2436 assert(mem != mem->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
2437
2438 assert(Opcode() == mem->Opcode() ||
2439 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw,
2440 "no mismatched stores, except on raw memory");
2441
2442 if (mem->outcnt() == 1 && // check for intervening uses
2443 mem->as_Store()->memory_size() <= this->memory_size()) {
2444 // If anybody other than 'this' uses 'mem', we cannot fold 'mem' away.
2445 // For example, 'mem' might be the final state at a conditional return.
2446 // Or, 'mem' might be used by some node which is live at the same time
2447 // 'this' is live, which might be unschedulable. So, require exactly
2448 // ONE user, the 'this' store, until such time as we clone 'mem' for
2449 // each of 'mem's uses (thus making the exactly-1-user-rule hold true).
2450 if (can_reshape) { // (%%% is this an anachronism?)
2451 set_req_X(MemNode::Memory, mem->in(MemNode::Memory),
2452 phase->is_IterGVN());
2453 } else {
2454 // It's OK to do this in the parser, since DU info is always accurate,
2455 // and the parser always refers to nodes via SafePointNode maps.
2456 set_req(MemNode::Memory, mem->in(MemNode::Memory));
2457 }
2458 return this;
2459 }
2460 }
2461
2462 // Capture an unaliased, unconditional, simple store into an initializer.
2463 // Or, if it is independent of the allocation, hoist it above the allocation.
2464 if (ReduceFieldZeroing && /*can_reshape &&*/
2465 mem->is_Proj() && mem->in(0)->is_Initialize()) {
2466 InitializeNode* init = mem->in(0)->as_Initialize();
2467 intptr_t offset = init->can_capture_store(this, phase, can_reshape);
2468 if (offset > 0) {
2469 Node* moved = init->capture_store(this, offset, phase, can_reshape);
2470 // If the InitializeNode captured me, it made a raw copy of me,
2471 // and I need to disappear.
2472 if (moved != NULL) {
2473 // %%% hack to ensure that Ideal returns a new node:
2474 mem = MergeMemNode::make(mem);
2475 return mem; // fold me away
2476 }
2477 }
2478 }
2479
2480 return NULL; // No further progress
2481 }
2482
2483 //------------------------------Value-----------------------------------------
2484 const Type *StoreNode::Value( PhaseTransform *phase ) const {
2485 // Either input is TOP ==> the result is TOP
2486 const Type *t1 = phase->type( in(MemNode::Memory) );
2487 if( t1 == Type::TOP ) return Type::TOP;
2488 const Type *t2 = phase->type( in(MemNode::Address) );
2489 if( t2 == Type::TOP ) return Type::TOP;
2490 const Type *t3 = phase->type( in(MemNode::ValueIn) );
2491 if( t3 == Type::TOP ) return Type::TOP;
2492 return Type::MEMORY;
2493 }
2494
2495 //------------------------------Identity---------------------------------------
2496 // Remove redundant stores:
2497 // Store(m, p, Load(m, p)) changes to m.
2498 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
2499 Node *StoreNode::Identity( PhaseTransform *phase ) {
2500 Node* mem = in(MemNode::Memory);
2501 Node* adr = in(MemNode::Address);
2502 Node* val = in(MemNode::ValueIn);
2503
2504 // Load then Store? Then the Store is useless
2505 if (val->is_Load() &&
2506 val->in(MemNode::Address)->eqv_uncast(adr) &&
2507 val->in(MemNode::Memory )->eqv_uncast(mem) &&
2508 val->as_Load()->store_Opcode() == Opcode()) {
2509 return mem;
2510 }
2511
2512 // Two stores in a row of the same value?
2513 if (mem->is_Store() &&
2514 mem->in(MemNode::Address)->eqv_uncast(adr) &&
2515 mem->in(MemNode::ValueIn)->eqv_uncast(val) &&
2516 mem->Opcode() == Opcode()) {
2517 return mem;
2518 }
2519
2520 // Store of zero anywhere into a freshly-allocated object?
2521 // Then the store is useless.
2522 // (It must already have been captured by the InitializeNode.)
2523 if (ReduceFieldZeroing && phase->type(val)->is_zero_type()) {
2524 // a newly allocated object is already all-zeroes everywhere
2525 if (mem->is_Proj() && mem->in(0)->is_Allocate()) {
2526 return mem;
2527 }
2528
2529 // the store may also apply to zero-bits in an earlier object
2530 Node* prev_mem = find_previous_store(phase);
2531 // Steps (a), (b): Walk past independent stores to find an exact match.
2532 if (prev_mem != NULL) {
2533 Node* prev_val = can_see_stored_value(prev_mem, phase);
2534 if (prev_val != NULL && phase->eqv(prev_val, val)) {
2535 // prev_val and val might differ by a cast; it would be good
2536 // to keep the more informative of the two.
2537 return mem;
2538 }
2539 }
2540 }
2541
2542 return this;
2543 }
2544
2545 //------------------------------match_edge-------------------------------------
2546 // Do we Match on this edge index or not? Match only memory & value
2547 uint StoreNode::match_edge(uint idx) const {
2548 return idx == MemNode::Address || idx == MemNode::ValueIn;
2549 }
2550
2551 //------------------------------cmp--------------------------------------------
2552 // Do not common stores up together. They generally have to be split
2553 // back up anyways, so do not bother.
2554 uint StoreNode::cmp( const Node &n ) const {
2555 return (&n == this); // Always fail except on self
2556 }
2557
2558 //------------------------------Ideal_masked_input-----------------------------
2559 // Check for a useless mask before a partial-word store
2560 // (StoreB ... (AndI valIn conIa) )
2561 // If (conIa & mask == mask) this simplifies to
2562 // (StoreB ... (valIn) )
2563 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
2564 Node *val = in(MemNode::ValueIn);
2565 if( val->Opcode() == Op_AndI ) {
2566 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2567 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
2568 set_req(MemNode::ValueIn, val->in(1));
2569 return this;
2570 }
2571 }
2572 return NULL;
2573 }
2574
2575
2576 //------------------------------Ideal_sign_extended_input----------------------
2577 // Check for useless sign-extension before a partial-word store
2578 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) )
2579 // If (conIL == conIR && conIR <= num_bits) this simplifies to
2580 // (StoreB ... (valIn) )
2581 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) {
2582 Node *val = in(MemNode::ValueIn);
2583 if( val->Opcode() == Op_RShiftI ) {
2584 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2585 if( t && t->is_con() && (t->get_con() <= num_bits) ) {
2586 Node *shl = val->in(1);
2587 if( shl->Opcode() == Op_LShiftI ) {
2588 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int();
2589 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) {
2590 set_req(MemNode::ValueIn, shl->in(1));
2591 return this;
2592 }
2593 }
2594 }
2595 }
2596 return NULL;
2597 }
2598
2599 //------------------------------value_never_loaded-----------------------------------
2600 // Determine whether there are any possible loads of the value stored.
2601 // For simplicity, we actually check if there are any loads from the
2602 // address stored to, not just for loads of the value stored by this node.
2603 //
2604 bool StoreNode::value_never_loaded( PhaseTransform *phase) const {
2605 Node *adr = in(Address);
2606 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
2607 if (adr_oop == NULL)
2608 return false;
2609 if (!adr_oop->is_known_instance_field())
2610 return false; // if not a distinct instance, there may be aliases of the address
2611 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
2612 Node *use = adr->fast_out(i);
2613 if (use->is_Load() || use->is_LoadStore()) {
2614 return false;
2615 }
2616 }
2617 return true;
2618 }
2619
2620 //=============================================================================
2621 //------------------------------Ideal------------------------------------------
2622 // If the store is from an AND mask that leaves the low bits untouched, then
2623 // we can skip the AND operation. If the store is from a sign-extension
2624 // (a left shift, then right shift) we can skip both.
2625 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
2626 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
2627 if( progress != NULL ) return progress;
2628
2629 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
2630 if( progress != NULL ) return progress;
2631
2632 // Finally check the default case
2633 return StoreNode::Ideal(phase, can_reshape);
2634 }
2635
2636 //=============================================================================
2637 //------------------------------Ideal------------------------------------------
2638 // If the store is from an AND mask that leaves the low bits untouched, then
2639 // we can skip the AND operation
2640 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
2641 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
2642 if( progress != NULL ) return progress;
2643
2644 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
2645 if( progress != NULL ) return progress;
2646
2647 // Finally check the default case
2648 return StoreNode::Ideal(phase, can_reshape);
2649 }
2650
2651 //=============================================================================
2652 //------------------------------Identity---------------------------------------
2653 Node *StoreCMNode::Identity( PhaseTransform *phase ) {
2654 // No need to card mark when storing a null ptr
2655 Node* my_store = in(MemNode::OopStore);
2656 if (my_store->is_Store()) {
2657 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) );
2658 if( t1 == TypePtr::NULL_PTR ) {
2659 return in(MemNode::Memory);
2660 }
2661 }
2662 return this;
2663 }
2664
2665 //=============================================================================
2666 //------------------------------Ideal---------------------------------------
2667 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){
2668 Node* progress = StoreNode::Ideal(phase, can_reshape);
2669 if (progress != NULL) return progress;
2670
2671 Node* my_store = in(MemNode::OopStore);
2672 if (my_store->is_MergeMem()) {
2673 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx());
2674 set_req(MemNode::OopStore, mem);
2675 return this;
2676 }
2677
2678 return NULL;
2679 }
2680
2681 //------------------------------Value-----------------------------------------
2682 const Type *StoreCMNode::Value( PhaseTransform *phase ) const {
2683 // Either input is TOP ==> the result is TOP
2684 const Type *t = phase->type( in(MemNode::Memory) );
2685 if( t == Type::TOP ) return Type::TOP;
2686 t = phase->type( in(MemNode::Address) );
2687 if( t == Type::TOP ) return Type::TOP;
2688 t = phase->type( in(MemNode::ValueIn) );
2689 if( t == Type::TOP ) return Type::TOP;
2690 // If extra input is TOP ==> the result is TOP
2691 t = phase->type( in(MemNode::OopStore) );
2692 if( t == Type::TOP ) return Type::TOP;
2693
2694 return StoreNode::Value( phase );
2695 }
2696
2697
2698 //=============================================================================
2699 //----------------------------------SCMemProjNode------------------------------
2700 const Type * SCMemProjNode::Value( PhaseTransform *phase ) const
2701 {
2702 return bottom_type();
2703 }
2704
2705 //=============================================================================
2706 //----------------------------------LoadStoreNode------------------------------
2707 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required )
2708 : Node(required),
2709 _type(rt),
2710 _adr_type(at)
2711 {
2712 init_req(MemNode::Control, c );
2713 init_req(MemNode::Memory , mem);
2714 init_req(MemNode::Address, adr);
2715 init_req(MemNode::ValueIn, val);
2716 init_class_id(Class_LoadStore);
2717 }
2718
2719 uint LoadStoreNode::ideal_reg() const {
2720 return _type->ideal_reg();
2721 }
2722
2723 bool LoadStoreNode::result_not_used() const {
2724 for( DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++ ) {
2725 Node *x = fast_out(i);
2726 if (x->Opcode() == Op_SCMemProj) continue;
2727 return false;
2728 }
2729 return true;
2730 }
2731
2732 uint LoadStoreNode::size_of() const { return sizeof(*this); }
2733
2734 //=============================================================================
2735 //----------------------------------LoadStoreConditionalNode--------------------
2736 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, NULL, TypeInt::BOOL, 5) {
2737 init_req(ExpectedIn, ex );
2738 }
2739
2740 //=============================================================================
2741 //-------------------------------adr_type--------------------------------------
2742 // Do we Match on this edge index or not? Do not match memory
2743 const TypePtr* ClearArrayNode::adr_type() const {
2744 Node *adr = in(3);
2745 if (adr == NULL) return NULL; // node is dead
2746 return MemNode::calculate_adr_type(adr->bottom_type());
2747 }
2748
2749 //------------------------------match_edge-------------------------------------
2750 // Do we Match on this edge index or not? Do not match memory
2751 uint ClearArrayNode::match_edge(uint idx) const {
2752 return idx > 1;
2753 }
2754
2755 //------------------------------Identity---------------------------------------
2756 // Clearing a zero length array does nothing
2757 Node *ClearArrayNode::Identity( PhaseTransform *phase ) {
2758 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
2759 }
2760
2761 //------------------------------Idealize---------------------------------------
2762 // Clearing a short array is faster with stores
2763 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape){
2764 const int unit = BytesPerLong;
2765 const TypeX* t = phase->type(in(2))->isa_intptr_t();
2766 if (!t) return NULL;
2767 if (!t->is_con()) return NULL;
2768 intptr_t raw_count = t->get_con();
2769 intptr_t size = raw_count;
2770 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
2771 // Clearing nothing uses the Identity call.
2772 // Negative clears are possible on dead ClearArrays
2773 // (see jck test stmt114.stmt11402.val).
2774 if (size <= 0 || size % unit != 0) return NULL;
2775 intptr_t count = size / unit;
2776 // Length too long; use fast hardware clear
2777 if (size > Matcher::init_array_short_size) return NULL;
2778 Node *mem = in(1);
2779 if( phase->type(mem)==Type::TOP ) return NULL;
2780 Node *adr = in(3);
2781 const Type* at = phase->type(adr);
2782 if( at==Type::TOP ) return NULL;
2783 const TypePtr* atp = at->isa_ptr();
2784 // adjust atp to be the correct array element address type
2785 if (atp == NULL) atp = TypePtr::BOTTOM;
2786 else atp = atp->add_offset(Type::OffsetBot);
2787 // Get base for derived pointer purposes
2788 if( adr->Opcode() != Op_AddP ) Unimplemented();
2789 Node *base = adr->in(1);
2790
2791 Node *zero = phase->makecon(TypeLong::ZERO);
2792 Node *off = phase->MakeConX(BytesPerLong);
2793 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
2794 count--;
2795 while( count-- ) {
2796 mem = phase->transform(mem);
2797 adr = phase->transform(new AddPNode(base,adr,off));
2798 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
2799 }
2800 return mem;
2801 }
2802
2803 //----------------------------step_through----------------------------------
2804 // Return allocation input memory edge if it is different instance
2805 // or itself if it is the one we are looking for.
2806 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) {
2807 Node* n = *np;
2808 assert(n->is_ClearArray(), "sanity");
2809 intptr_t offset;
2810 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
2811 // This method is called only before Allocate nodes are expanded
2812 // during macro nodes expansion. Before that ClearArray nodes are
2813 // only generated in PhaseMacroExpand::generate_arraycopy() (before
2814 // Allocate nodes are expanded) which follows allocations.
2815 assert(alloc != NULL, "should have allocation");
2816 if (alloc->_idx == instance_id) {
2817 // Can not bypass initialization of the instance we are looking for.
2818 return false;
2819 }
2820 // Otherwise skip it.
2821 InitializeNode* init = alloc->initialization();
2822 if (init != NULL)
2823 *np = init->in(TypeFunc::Memory);
2824 else
2825 *np = alloc->in(TypeFunc::Memory);
2826 return true;
2827 }
2828
2829 //----------------------------clear_memory-------------------------------------
2830 // Generate code to initialize object storage to zero.
2831 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2832 intptr_t start_offset,
2833 Node* end_offset,
2834 PhaseGVN* phase) {
2835 intptr_t offset = start_offset;
2836
2837 int unit = BytesPerLong;
2838 if ((offset % unit) != 0) {
2839 Node* adr = new AddPNode(dest, dest, phase->MakeConX(offset));
2840 adr = phase->transform(adr);
2841 const TypePtr* atp = TypeRawPtr::BOTTOM;
2842 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
2843 mem = phase->transform(mem);
2844 offset += BytesPerInt;
2845 }
2846 assert((offset % unit) == 0, "");
2847
2848 // Initialize the remaining stuff, if any, with a ClearArray.
2849 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase);
2850 }
2851
2852 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2853 Node* start_offset,
2854 Node* end_offset,
2855 PhaseGVN* phase) {
2856 if (start_offset == end_offset) {
2857 // nothing to do
2858 return mem;
2859 }
2860
2861 int unit = BytesPerLong;
2862 Node* zbase = start_offset;
2863 Node* zend = end_offset;
2864
2865 // Scale to the unit required by the CPU:
2866 if (!Matcher::init_array_count_is_in_bytes) {
2867 Node* shift = phase->intcon(exact_log2(unit));
2868 zbase = phase->transform(new URShiftXNode(zbase, shift) );
2869 zend = phase->transform(new URShiftXNode(zend, shift) );
2870 }
2871
2872 // Bulk clear double-words
2873 Node* zsize = phase->transform(new SubXNode(zend, zbase) );
2874 Node* adr = phase->transform(new AddPNode(dest, dest, start_offset) );
2875 mem = new ClearArrayNode(ctl, mem, zsize, adr);
2876 return phase->transform(mem);
2877 }
2878
2879 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2880 intptr_t start_offset,
2881 intptr_t end_offset,
2882 PhaseGVN* phase) {
2883 if (start_offset == end_offset) {
2884 // nothing to do
2885 return mem;
2886 }
2887
2888 assert((end_offset % BytesPerInt) == 0, "odd end offset");
2889 intptr_t done_offset = end_offset;
2890 if ((done_offset % BytesPerLong) != 0) {
2891 done_offset -= BytesPerInt;
2892 }
2893 if (done_offset > start_offset) {
2894 mem = clear_memory(ctl, mem, dest,
2895 start_offset, phase->MakeConX(done_offset), phase);
2896 }
2897 if (done_offset < end_offset) { // emit the final 32-bit store
2898 Node* adr = new AddPNode(dest, dest, phase->MakeConX(done_offset));
2899 adr = phase->transform(adr);
2900 const TypePtr* atp = TypeRawPtr::BOTTOM;
2901 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
2902 mem = phase->transform(mem);
2903 done_offset += BytesPerInt;
2904 }
2905 assert(done_offset == end_offset, "");
2906 return mem;
2907 }
2908
2909 //=============================================================================
2910 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
2911 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)),
2912 _adr_type(C->get_adr_type(alias_idx))
2913 {
2914 init_class_id(Class_MemBar);
2915 Node* top = C->top();
2916 init_req(TypeFunc::I_O,top);
2917 init_req(TypeFunc::FramePtr,top);
2918 init_req(TypeFunc::ReturnAdr,top);
2919 if (precedent != NULL)
2920 init_req(TypeFunc::Parms, precedent);
2921 }
2922
2923 //------------------------------cmp--------------------------------------------
2924 uint MemBarNode::hash() const { return NO_HASH; }
2925 uint MemBarNode::cmp( const Node &n ) const {
2926 return (&n == this); // Always fail except on self
2927 }
2928
2929 //------------------------------make-------------------------------------------
2930 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
2931 switch (opcode) {
2932 case Op_MemBarAcquire: return new MemBarAcquireNode(C, atp, pn);
2933 case Op_LoadFence: return new LoadFenceNode(C, atp, pn);
2934 case Op_MemBarRelease: return new MemBarReleaseNode(C, atp, pn);
2935 case Op_StoreFence: return new StoreFenceNode(C, atp, pn);
2936 case Op_MemBarAcquireLock: return new MemBarAcquireLockNode(C, atp, pn);
2937 case Op_MemBarReleaseLock: return new MemBarReleaseLockNode(C, atp, pn);
2938 case Op_MemBarVolatile: return new MemBarVolatileNode(C, atp, pn);
2939 case Op_MemBarCPUOrder: return new MemBarCPUOrderNode(C, atp, pn);
2940 case Op_Initialize: return new InitializeNode(C, atp, pn);
2941 case Op_MemBarStoreStore: return new MemBarStoreStoreNode(C, atp, pn);
2942 default: ShouldNotReachHere(); return NULL;
2943 }
2944 }
2945
2946 //------------------------------Ideal------------------------------------------
2947 // Return a node which is more "ideal" than the current node. Strip out
2948 // control copies
2949 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2950 if (remove_dead_region(phase, can_reshape)) return this;
2951 // Don't bother trying to transform a dead node
2952 if (in(0) && in(0)->is_top()) {
2953 return NULL;
2954 }
2955
2956 bool progress = false;
2957 // Eliminate volatile MemBars for scalar replaced objects.
2958 if (can_reshape && req() == (Precedent+1)) {
2959 bool eliminate = false;
2960 int opc = Opcode();
2961 if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) {
2962 // Volatile field loads and stores.
2963 Node* my_mem = in(MemBarNode::Precedent);
2964 // The MembarAquire may keep an unused LoadNode alive through the Precedent edge
2965 if ((my_mem != NULL) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) {
2966 // if the Precedent is a decodeN and its input (a Load) is used at more than one place,
2967 // replace this Precedent (decodeN) with the Load instead.
2968 if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1)) {
2969 Node* load_node = my_mem->in(1);
2970 set_req(MemBarNode::Precedent, load_node);
2971 phase->is_IterGVN()->_worklist.push(my_mem);
2972 my_mem = load_node;
2973 } else {
2974 assert(my_mem->unique_out() == this, "sanity");
2975 del_req(Precedent);
2976 phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later
2977 my_mem = NULL;
2978 }
2979 progress = true;
2980 }
2981 if (my_mem != NULL && my_mem->is_Mem()) {
2982 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
2983 // Check for scalar replaced object reference.
2984 if( t_oop != NULL && t_oop->is_known_instance_field() &&
2985 t_oop->offset() != Type::OffsetBot &&
2986 t_oop->offset() != Type::OffsetTop) {
2987 eliminate = true;
2988 }
2989 }
2990 } else if (opc == Op_MemBarRelease) {
2991 // Final field stores.
2992 Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent), phase);
2993 if ((alloc != NULL) && alloc->is_Allocate() &&
2994 alloc->as_Allocate()->_is_non_escaping) {
2995 // The allocated object does not escape.
2996 eliminate = true;
2997 }
2998 }
2999 if (eliminate) {
3000 // Replace MemBar projections by its inputs.
3001 PhaseIterGVN* igvn = phase->is_IterGVN();
3002 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
3003 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
3004 // Must return either the original node (now dead) or a new node
3005 // (Do not return a top here, since that would break the uniqueness of top.)
3006 return new ConINode(TypeInt::ZERO);
3007 }
3008 }
3009 return progress ? this : NULL;
3010 }
3011
3012 //------------------------------Value------------------------------------------
3013 const Type *MemBarNode::Value( PhaseTransform *phase ) const {
3014 if( !in(0) ) return Type::TOP;
3015 if( phase->type(in(0)) == Type::TOP )
3016 return Type::TOP;
3017 return TypeTuple::MEMBAR;
3018 }
3019
3020 //------------------------------match------------------------------------------
3021 // Construct projections for memory.
3022 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) {
3023 switch (proj->_con) {
3024 case TypeFunc::Control:
3025 case TypeFunc::Memory:
3026 return new MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
3027 }
3028 ShouldNotReachHere();
3029 return NULL;
3030 }
3031
3032 //===========================InitializeNode====================================
3033 // SUMMARY:
3034 // This node acts as a memory barrier on raw memory, after some raw stores.
3035 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
3036 // The Initialize can 'capture' suitably constrained stores as raw inits.
3037 // It can coalesce related raw stores into larger units (called 'tiles').
3038 // It can avoid zeroing new storage for memory units which have raw inits.
3039 // At macro-expansion, it is marked 'complete', and does not optimize further.
3040 //
3041 // EXAMPLE:
3042 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
3043 // ctl = incoming control; mem* = incoming memory
3044 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
3045 // First allocate uninitialized memory and fill in the header:
3046 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
3047 // ctl := alloc.Control; mem* := alloc.Memory*
3048 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
3049 // Then initialize to zero the non-header parts of the raw memory block:
3050 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
3051 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
3052 // After the initialize node executes, the object is ready for service:
3053 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
3054 // Suppose its body is immediately initialized as {1,2}:
3055 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3056 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3057 // mem.SLICE(#short[*]) := store2
3058 //
3059 // DETAILS:
3060 // An InitializeNode collects and isolates object initialization after
3061 // an AllocateNode and before the next possible safepoint. As a
3062 // memory barrier (MemBarNode), it keeps critical stores from drifting
3063 // down past any safepoint or any publication of the allocation.
3064 // Before this barrier, a newly-allocated object may have uninitialized bits.
3065 // After this barrier, it may be treated as a real oop, and GC is allowed.
3066 //
3067 // The semantics of the InitializeNode include an implicit zeroing of
3068 // the new object from object header to the end of the object.
3069 // (The object header and end are determined by the AllocateNode.)
3070 //
3071 // Certain stores may be added as direct inputs to the InitializeNode.
3072 // These stores must update raw memory, and they must be to addresses
3073 // derived from the raw address produced by AllocateNode, and with
3074 // a constant offset. They must be ordered by increasing offset.
3075 // The first one is at in(RawStores), the last at in(req()-1).
3076 // Unlike most memory operations, they are not linked in a chain,
3077 // but are displayed in parallel as users of the rawmem output of
3078 // the allocation.
3079 //
3080 // (See comments in InitializeNode::capture_store, which continue
3081 // the example given above.)
3082 //
3083 // When the associated Allocate is macro-expanded, the InitializeNode
3084 // may be rewritten to optimize collected stores. A ClearArrayNode
3085 // may also be created at that point to represent any required zeroing.
3086 // The InitializeNode is then marked 'complete', prohibiting further
3087 // capturing of nearby memory operations.
3088 //
3089 // During macro-expansion, all captured initializations which store
3090 // constant values of 32 bits or smaller are coalesced (if advantageous)
3091 // into larger 'tiles' 32 or 64 bits. This allows an object to be
3092 // initialized in fewer memory operations. Memory words which are
3093 // covered by neither tiles nor non-constant stores are pre-zeroed
3094 // by explicit stores of zero. (The code shape happens to do all
3095 // zeroing first, then all other stores, with both sequences occurring
3096 // in order of ascending offsets.)
3097 //
3098 // Alternatively, code may be inserted between an AllocateNode and its
3099 // InitializeNode, to perform arbitrary initialization of the new object.
3100 // E.g., the object copying intrinsics insert complex data transfers here.
3101 // The initialization must then be marked as 'complete' disable the
3102 // built-in zeroing semantics and the collection of initializing stores.
3103 //
3104 // While an InitializeNode is incomplete, reads from the memory state
3105 // produced by it are optimizable if they match the control edge and
3106 // new oop address associated with the allocation/initialization.
3107 // They return a stored value (if the offset matches) or else zero.
3108 // A write to the memory state, if it matches control and address,
3109 // and if it is to a constant offset, may be 'captured' by the
3110 // InitializeNode. It is cloned as a raw memory operation and rewired
3111 // inside the initialization, to the raw oop produced by the allocation.
3112 // Operations on addresses which are provably distinct (e.g., to
3113 // other AllocateNodes) are allowed to bypass the initialization.
3114 //
3115 // The effect of all this is to consolidate object initialization
3116 // (both arrays and non-arrays, both piecewise and bulk) into a
3117 // single location, where it can be optimized as a unit.
3118 //
3119 // Only stores with an offset less than TrackedInitializationLimit words
3120 // will be considered for capture by an InitializeNode. This puts a
3121 // reasonable limit on the complexity of optimized initializations.
3122
3123 //---------------------------InitializeNode------------------------------------
3124 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
3125 : _is_complete(Incomplete), _does_not_escape(false),
3126 MemBarNode(C, adr_type, rawoop)
3127 {
3128 init_class_id(Class_Initialize);
3129
3130 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
3131 assert(in(RawAddress) == rawoop, "proper init");
3132 // Note: allocation() can be NULL, for secondary initialization barriers
3133 }
3134
3135 // Since this node is not matched, it will be processed by the
3136 // register allocator. Declare that there are no constraints
3137 // on the allocation of the RawAddress edge.
3138 const RegMask &InitializeNode::in_RegMask(uint idx) const {
3139 // This edge should be set to top, by the set_complete. But be conservative.
3140 if (idx == InitializeNode::RawAddress)
3141 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
3142 return RegMask::Empty;
3143 }
3144
3145 Node* InitializeNode::memory(uint alias_idx) {
3146 Node* mem = in(Memory);
3147 if (mem->is_MergeMem()) {
3148 return mem->as_MergeMem()->memory_at(alias_idx);
3149 } else {
3150 // incoming raw memory is not split
3151 return mem;
3152 }
3153 }
3154
3155 bool InitializeNode::is_non_zero() {
3156 if (is_complete()) return false;
3157 remove_extra_zeroes();
3158 return (req() > RawStores);
3159 }
3160
3161 void InitializeNode::set_complete(PhaseGVN* phase) {
3162 assert(!is_complete(), "caller responsibility");
3163 _is_complete = Complete;
3164
3165 // After this node is complete, it contains a bunch of
3166 // raw-memory initializations. There is no need for
3167 // it to have anything to do with non-raw memory effects.
3168 // Therefore, tell all non-raw users to re-optimize themselves,
3169 // after skipping the memory effects of this initialization.
3170 PhaseIterGVN* igvn = phase->is_IterGVN();
3171 if (igvn) igvn->add_users_to_worklist(this);
3172 }
3173
3174 // convenience function
3175 // return false if the init contains any stores already
3176 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
3177 InitializeNode* init = initialization();
3178 if (init == NULL || init->is_complete()) return false;
3179 init->remove_extra_zeroes();
3180 // for now, if this allocation has already collected any inits, bail:
3181 if (init->is_non_zero()) return false;
3182 init->set_complete(phase);
3183 return true;
3184 }
3185
3186 void InitializeNode::remove_extra_zeroes() {
3187 if (req() == RawStores) return;
3188 Node* zmem = zero_memory();
3189 uint fill = RawStores;
3190 for (uint i = fill; i < req(); i++) {
3191 Node* n = in(i);
3192 if (n->is_top() || n == zmem) continue; // skip
3193 if (fill < i) set_req(fill, n); // compact
3194 ++fill;
3195 }
3196 // delete any empty spaces created:
3197 while (fill < req()) {
3198 del_req(fill);
3199 }
3200 }
3201
3202 // Helper for remembering which stores go with which offsets.
3203 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) {
3204 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
3205 intptr_t offset = -1;
3206 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
3207 phase, offset);
3208 if (base == NULL) return -1; // something is dead,
3209 if (offset < 0) return -1; // dead, dead
3210 return offset;
3211 }
3212
3213 // Helper for proving that an initialization expression is
3214 // "simple enough" to be folded into an object initialization.
3215 // Attempts to prove that a store's initial value 'n' can be captured
3216 // within the initialization without creating a vicious cycle, such as:
3217 // { Foo p = new Foo(); p.next = p; }
3218 // True for constants and parameters and small combinations thereof.
3219 bool InitializeNode::detect_init_independence(Node* n, int& count) {
3220 if (n == NULL) return true; // (can this really happen?)
3221 if (n->is_Proj()) n = n->in(0);
3222 if (n == this) return false; // found a cycle
3223 if (n->is_Con()) return true;
3224 if (n->is_Start()) return true; // params, etc., are OK
3225 if (n->is_Root()) return true; // even better
3226
3227 Node* ctl = n->in(0);
3228 if (ctl != NULL && !ctl->is_top()) {
3229 if (ctl->is_Proj()) ctl = ctl->in(0);
3230 if (ctl == this) return false;
3231
3232 // If we already know that the enclosing memory op is pinned right after
3233 // the init, then any control flow that the store has picked up
3234 // must have preceded the init, or else be equal to the init.
3235 // Even after loop optimizations (which might change control edges)
3236 // a store is never pinned *before* the availability of its inputs.
3237 if (!MemNode::all_controls_dominate(n, this))
3238 return false; // failed to prove a good control
3239 }
3240
3241 // Check data edges for possible dependencies on 'this'.
3242 if ((count += 1) > 20) return false; // complexity limit
3243 for (uint i = 1; i < n->req(); i++) {
3244 Node* m = n->in(i);
3245 if (m == NULL || m == n || m->is_top()) continue;
3246 uint first_i = n->find_edge(m);
3247 if (i != first_i) continue; // process duplicate edge just once
3248 if (!detect_init_independence(m, count)) {
3249 return false;
3250 }
3251 }
3252
3253 return true;
3254 }
3255
3256 // Here are all the checks a Store must pass before it can be moved into
3257 // an initialization. Returns zero if a check fails.
3258 // On success, returns the (constant) offset to which the store applies,
3259 // within the initialized memory.
3260 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase, bool can_reshape) {
3261 const int FAIL = 0;
3262 if (st->req() != MemNode::ValueIn + 1)
3263 return FAIL; // an inscrutable StoreNode (card mark?)
3264 Node* ctl = st->in(MemNode::Control);
3265 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this))
3266 return FAIL; // must be unconditional after the initialization
3267 Node* mem = st->in(MemNode::Memory);
3268 if (!(mem->is_Proj() && mem->in(0) == this))
3269 return FAIL; // must not be preceded by other stores
3270 Node* adr = st->in(MemNode::Address);
3271 intptr_t offset;
3272 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
3273 if (alloc == NULL)
3274 return FAIL; // inscrutable address
3275 if (alloc != allocation())
3276 return FAIL; // wrong allocation! (store needs to float up)
3277 Node* val = st->in(MemNode::ValueIn);
3278 int complexity_count = 0;
3279 if (!detect_init_independence(val, complexity_count))
3280 return FAIL; // stored value must be 'simple enough'
3281
3282 // The Store can be captured only if nothing after the allocation
3283 // and before the Store is using the memory location that the store
3284 // overwrites.
3285 bool failed = false;
3286 // If is_complete_with_arraycopy() is true the shape of the graph is
3287 // well defined and is safe so no need for extra checks.
3288 if (!is_complete_with_arraycopy()) {
3289 // We are going to look at each use of the memory state following
3290 // the allocation to make sure nothing reads the memory that the
3291 // Store writes.
3292 const TypePtr* t_adr = phase->type(adr)->isa_ptr();
3293 int alias_idx = phase->C->get_alias_index(t_adr);
3294 ResourceMark rm;
3295 Unique_Node_List mems;
3296 mems.push(mem);
3297 Node* unique_merge = NULL;
3298 for (uint next = 0; next < mems.size(); ++next) {
3299 Node *m = mems.at(next);
3300 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
3301 Node *n = m->fast_out(j);
3302 if (n->outcnt() == 0) {
3303 continue;
3304 }
3305 if (n == st) {
3306 continue;
3307 } else if (n->in(0) != NULL && n->in(0) != ctl) {
3308 // If the control of this use is different from the control
3309 // of the Store which is right after the InitializeNode then
3310 // this node cannot be between the InitializeNode and the
3311 // Store.
3312 continue;
3313 } else if (n->is_MergeMem()) {
3314 if (n->as_MergeMem()->memory_at(alias_idx) == m) {
3315 // We can hit a MergeMemNode (that will likely go away
3316 // later) that is a direct use of the memory state
3317 // following the InitializeNode on the same slice as the
3318 // store node that we'd like to capture. We need to check
3319 // the uses of the MergeMemNode.
3320 mems.push(n);
3321 }
3322 } else if (n->is_Mem()) {
3323 Node* other_adr = n->in(MemNode::Address);
3324 if (other_adr == adr) {
3325 failed = true;
3326 break;
3327 } else {
3328 const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr();
3329 if (other_t_adr != NULL) {
3330 int other_alias_idx = phase->C->get_alias_index(other_t_adr);
3331 if (other_alias_idx == alias_idx) {
3332 // A load from the same memory slice as the store right
3333 // after the InitializeNode. We check the control of the
3334 // object/array that is loaded from. If it's the same as
3335 // the store control then we cannot capture the store.
3336 assert(!n->is_Store(), "2 stores to same slice on same control?");
3337 Node* base = other_adr;
3338 assert(base->is_AddP(), err_msg_res("should be addp but is %s", base->Name()));
3339 base = base->in(AddPNode::Base);
3340 if (base != NULL) {
3341 base = base->uncast();
3342 if (base->is_Proj() && base->in(0) == alloc) {
3343 failed = true;
3344 break;
3345 }
3346 }
3347 }
3348 }
3349 }
3350 } else {
3351 failed = true;
3352 break;
3353 }
3354 }
3355 }
3356 }
3357 if (failed) {
3358 if (!can_reshape) {
3359 // We decided we couldn't capture the store during parsing. We
3360 // should try again during the next IGVN once the graph is
3361 // cleaner.
3362 phase->C->record_for_igvn(st);
3363 }
3364 return FAIL;
3365 }
3366
3367 return offset; // success
3368 }
3369
3370 // Find the captured store in(i) which corresponds to the range
3371 // [start..start+size) in the initialized object.
3372 // If there is one, return its index i. If there isn't, return the
3373 // negative of the index where it should be inserted.
3374 // Return 0 if the queried range overlaps an initialization boundary
3375 // or if dead code is encountered.
3376 // If size_in_bytes is zero, do not bother with overlap checks.
3377 int InitializeNode::captured_store_insertion_point(intptr_t start,
3378 int size_in_bytes,
3379 PhaseTransform* phase) {
3380 const int FAIL = 0, MAX_STORE = BytesPerLong;
3381
3382 if (is_complete())
3383 return FAIL; // arraycopy got here first; punt
3384
3385 assert(allocation() != NULL, "must be present");
3386
3387 // no negatives, no header fields:
3388 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
3389
3390 // after a certain size, we bail out on tracking all the stores:
3391 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3392 if (start >= ti_limit) return FAIL;
3393
3394 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
3395 if (i >= limit) return -(int)i; // not found; here is where to put it
3396
3397 Node* st = in(i);
3398 intptr_t st_off = get_store_offset(st, phase);
3399 if (st_off < 0) {
3400 if (st != zero_memory()) {
3401 return FAIL; // bail out if there is dead garbage
3402 }
3403 } else if (st_off > start) {
3404 // ...we are done, since stores are ordered
3405 if (st_off < start + size_in_bytes) {
3406 return FAIL; // the next store overlaps
3407 }
3408 return -(int)i; // not found; here is where to put it
3409 } else if (st_off < start) {
3410 if (size_in_bytes != 0 &&
3411 start < st_off + MAX_STORE &&
3412 start < st_off + st->as_Store()->memory_size()) {
3413 return FAIL; // the previous store overlaps
3414 }
3415 } else {
3416 if (size_in_bytes != 0 &&
3417 st->as_Store()->memory_size() != size_in_bytes) {
3418 return FAIL; // mismatched store size
3419 }
3420 return i;
3421 }
3422
3423 ++i;
3424 }
3425 }
3426
3427 // Look for a captured store which initializes at the offset 'start'
3428 // with the given size. If there is no such store, and no other
3429 // initialization interferes, then return zero_memory (the memory
3430 // projection of the AllocateNode).
3431 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
3432 PhaseTransform* phase) {
3433 assert(stores_are_sane(phase), "");
3434 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3435 if (i == 0) {
3436 return NULL; // something is dead
3437 } else if (i < 0) {
3438 return zero_memory(); // just primordial zero bits here
3439 } else {
3440 Node* st = in(i); // here is the store at this position
3441 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
3442 return st;
3443 }
3444 }
3445
3446 // Create, as a raw pointer, an address within my new object at 'offset'.
3447 Node* InitializeNode::make_raw_address(intptr_t offset,
3448 PhaseTransform* phase) {
3449 Node* addr = in(RawAddress);
3450 if (offset != 0) {
3451 Compile* C = phase->C;
3452 addr = phase->transform( new AddPNode(C->top(), addr,
3453 phase->MakeConX(offset)) );
3454 }
3455 return addr;
3456 }
3457
3458 // Clone the given store, converting it into a raw store
3459 // initializing a field or element of my new object.
3460 // Caller is responsible for retiring the original store,
3461 // with subsume_node or the like.
3462 //
3463 // From the example above InitializeNode::InitializeNode,
3464 // here are the old stores to be captured:
3465 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3466 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3467 //
3468 // Here is the changed code; note the extra edges on init:
3469 // alloc = (Allocate ...)
3470 // rawoop = alloc.RawAddress
3471 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
3472 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
3473 // init = (Initialize alloc.Control alloc.Memory rawoop
3474 // rawstore1 rawstore2)
3475 //
3476 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
3477 PhaseTransform* phase, bool can_reshape) {
3478 assert(stores_are_sane(phase), "");
3479
3480 if (start < 0) return NULL;
3481 assert(can_capture_store(st, phase, can_reshape) == start, "sanity");
3482
3483 Compile* C = phase->C;
3484 int size_in_bytes = st->memory_size();
3485 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3486 if (i == 0) return NULL; // bail out
3487 Node* prev_mem = NULL; // raw memory for the captured store
3488 if (i > 0) {
3489 prev_mem = in(i); // there is a pre-existing store under this one
3490 set_req(i, C->top()); // temporarily disconnect it
3491 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
3492 } else {
3493 i = -i; // no pre-existing store
3494 prev_mem = zero_memory(); // a slice of the newly allocated object
3495 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
3496 set_req(--i, C->top()); // reuse this edge; it has been folded away
3497 else
3498 ins_req(i, C->top()); // build a new edge
3499 }
3500 Node* new_st = st->clone();
3501 new_st->set_req(MemNode::Control, in(Control));
3502 new_st->set_req(MemNode::Memory, prev_mem);
3503 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
3504 new_st = phase->transform(new_st);
3505
3506 // At this point, new_st might have swallowed a pre-existing store
3507 // at the same offset, or perhaps new_st might have disappeared,
3508 // if it redundantly stored the same value (or zero to fresh memory).
3509
3510 // In any case, wire it in:
3511 phase->igvn_rehash_node_delayed(this);
3512 set_req(i, new_st);
3513
3514 // The caller may now kill the old guy.
3515 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
3516 assert(check_st == new_st || check_st == NULL, "must be findable");
3517 assert(!is_complete(), "");
3518 return new_st;
3519 }
3520
3521 static bool store_constant(jlong* tiles, int num_tiles,
3522 intptr_t st_off, int st_size,
3523 jlong con) {
3524 if ((st_off & (st_size-1)) != 0)
3525 return false; // strange store offset (assume size==2**N)
3526 address addr = (address)tiles + st_off;
3527 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
3528 switch (st_size) {
3529 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
3530 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
3531 case sizeof(jint): *(jint*) addr = (jint) con; break;
3532 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
3533 default: return false; // strange store size (detect size!=2**N here)
3534 }
3535 return true; // return success to caller
3536 }
3537
3538 // Coalesce subword constants into int constants and possibly
3539 // into long constants. The goal, if the CPU permits,
3540 // is to initialize the object with a small number of 64-bit tiles.
3541 // Also, convert floating-point constants to bit patterns.
3542 // Non-constants are not relevant to this pass.
3543 //
3544 // In terms of the running example on InitializeNode::InitializeNode
3545 // and InitializeNode::capture_store, here is the transformation
3546 // of rawstore1 and rawstore2 into rawstore12:
3547 // alloc = (Allocate ...)
3548 // rawoop = alloc.RawAddress
3549 // tile12 = 0x00010002
3550 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
3551 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
3552 //
3553 void
3554 InitializeNode::coalesce_subword_stores(intptr_t header_size,
3555 Node* size_in_bytes,
3556 PhaseGVN* phase) {
3557 Compile* C = phase->C;
3558
3559 assert(stores_are_sane(phase), "");
3560 // Note: After this pass, they are not completely sane,
3561 // since there may be some overlaps.
3562
3563 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
3564
3565 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3566 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
3567 size_limit = MIN2(size_limit, ti_limit);
3568 size_limit = align_size_up(size_limit, BytesPerLong);
3569 int num_tiles = size_limit / BytesPerLong;
3570
3571 // allocate space for the tile map:
3572 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
3573 jlong tiles_buf[small_len];
3574 Node* nodes_buf[small_len];
3575 jlong inits_buf[small_len];
3576 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
3577 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3578 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
3579 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
3580 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
3581 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3582 // tiles: exact bitwise model of all primitive constants
3583 // nodes: last constant-storing node subsumed into the tiles model
3584 // inits: which bytes (in each tile) are touched by any initializations
3585
3586 //// Pass A: Fill in the tile model with any relevant stores.
3587
3588 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
3589 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
3590 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
3591 Node* zmem = zero_memory(); // initially zero memory state
3592 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3593 Node* st = in(i);
3594 intptr_t st_off = get_store_offset(st, phase);
3595
3596 // Figure out the store's offset and constant value:
3597 if (st_off < header_size) continue; //skip (ignore header)
3598 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
3599 int st_size = st->as_Store()->memory_size();
3600 if (st_off + st_size > size_limit) break;
3601
3602 // Record which bytes are touched, whether by constant or not.
3603 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
3604 continue; // skip (strange store size)
3605
3606 const Type* val = phase->type(st->in(MemNode::ValueIn));
3607 if (!val->singleton()) continue; //skip (non-con store)
3608 BasicType type = val->basic_type();
3609
3610 jlong con = 0;
3611 switch (type) {
3612 case T_INT: con = val->is_int()->get_con(); break;
3613 case T_LONG: con = val->is_long()->get_con(); break;
3614 case T_FLOAT: con = jint_cast(val->getf()); break;
3615 case T_DOUBLE: con = jlong_cast(val->getd()); break;
3616 default: continue; //skip (odd store type)
3617 }
3618
3619 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
3620 st->Opcode() == Op_StoreL) {
3621 continue; // This StoreL is already optimal.
3622 }
3623
3624 // Store down the constant.
3625 store_constant(tiles, num_tiles, st_off, st_size, con);
3626
3627 intptr_t j = st_off >> LogBytesPerLong;
3628
3629 if (type == T_INT && st_size == BytesPerInt
3630 && (st_off & BytesPerInt) == BytesPerInt) {
3631 jlong lcon = tiles[j];
3632 if (!Matcher::isSimpleConstant64(lcon) &&
3633 st->Opcode() == Op_StoreI) {
3634 // This StoreI is already optimal by itself.
3635 jint* intcon = (jint*) &tiles[j];
3636 intcon[1] = 0; // undo the store_constant()
3637
3638 // If the previous store is also optimal by itself, back up and
3639 // undo the action of the previous loop iteration... if we can.
3640 // But if we can't, just let the previous half take care of itself.
3641 st = nodes[j];
3642 st_off -= BytesPerInt;
3643 con = intcon[0];
3644 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) {
3645 assert(st_off >= header_size, "still ignoring header");
3646 assert(get_store_offset(st, phase) == st_off, "must be");
3647 assert(in(i-1) == zmem, "must be");
3648 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
3649 assert(con == tcon->is_int()->get_con(), "must be");
3650 // Undo the effects of the previous loop trip, which swallowed st:
3651 intcon[0] = 0; // undo store_constant()
3652 set_req(i-1, st); // undo set_req(i, zmem)
3653 nodes[j] = NULL; // undo nodes[j] = st
3654 --old_subword; // undo ++old_subword
3655 }
3656 continue; // This StoreI is already optimal.
3657 }
3658 }
3659
3660 // This store is not needed.
3661 set_req(i, zmem);
3662 nodes[j] = st; // record for the moment
3663 if (st_size < BytesPerLong) // something has changed
3664 ++old_subword; // includes int/float, but who's counting...
3665 else ++old_long;
3666 }
3667
3668 if ((old_subword + old_long) == 0)
3669 return; // nothing more to do
3670
3671 //// Pass B: Convert any non-zero tiles into optimal constant stores.
3672 // Be sure to insert them before overlapping non-constant stores.
3673 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
3674 for (int j = 0; j < num_tiles; j++) {
3675 jlong con = tiles[j];
3676 jlong init = inits[j];
3677 if (con == 0) continue;
3678 jint con0, con1; // split the constant, address-wise
3679 jint init0, init1; // split the init map, address-wise
3680 { union { jlong con; jint intcon[2]; } u;
3681 u.con = con;
3682 con0 = u.intcon[0];
3683 con1 = u.intcon[1];
3684 u.con = init;
3685 init0 = u.intcon[0];
3686 init1 = u.intcon[1];
3687 }
3688
3689 Node* old = nodes[j];
3690 assert(old != NULL, "need the prior store");
3691 intptr_t offset = (j * BytesPerLong);
3692
3693 bool split = !Matcher::isSimpleConstant64(con);
3694
3695 if (offset < header_size) {
3696 assert(offset + BytesPerInt >= header_size, "second int counts");
3697 assert(*(jint*)&tiles[j] == 0, "junk in header");
3698 split = true; // only the second word counts
3699 // Example: int a[] = { 42 ... }
3700 } else if (con0 == 0 && init0 == -1) {
3701 split = true; // first word is covered by full inits
3702 // Example: int a[] = { ... foo(), 42 ... }
3703 } else if (con1 == 0 && init1 == -1) {
3704 split = true; // second word is covered by full inits
3705 // Example: int a[] = { ... 42, foo() ... }
3706 }
3707
3708 // Here's a case where init0 is neither 0 nor -1:
3709 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
3710 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
3711 // In this case the tile is not split; it is (jlong)42.
3712 // The big tile is stored down, and then the foo() value is inserted.
3713 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
3714
3715 Node* ctl = old->in(MemNode::Control);
3716 Node* adr = make_raw_address(offset, phase);
3717 const TypePtr* atp = TypeRawPtr::BOTTOM;
3718
3719 // One or two coalesced stores to plop down.
3720 Node* st[2];
3721 intptr_t off[2];
3722 int nst = 0;
3723 if (!split) {
3724 ++new_long;
3725 off[nst] = offset;
3726 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3727 phase->longcon(con), T_LONG, MemNode::unordered);
3728 } else {
3729 // Omit either if it is a zero.
3730 if (con0 != 0) {
3731 ++new_int;
3732 off[nst] = offset;
3733 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3734 phase->intcon(con0), T_INT, MemNode::unordered);
3735 }
3736 if (con1 != 0) {
3737 ++new_int;
3738 offset += BytesPerInt;
3739 adr = make_raw_address(offset, phase);
3740 off[nst] = offset;
3741 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3742 phase->intcon(con1), T_INT, MemNode::unordered);
3743 }
3744 }
3745
3746 // Insert second store first, then the first before the second.
3747 // Insert each one just before any overlapping non-constant stores.
3748 while (nst > 0) {
3749 Node* st1 = st[--nst];
3750 C->copy_node_notes_to(st1, old);
3751 st1 = phase->transform(st1);
3752 offset = off[nst];
3753 assert(offset >= header_size, "do not smash header");
3754 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
3755 guarantee(ins_idx != 0, "must re-insert constant store");
3756 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
3757 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
3758 set_req(--ins_idx, st1);
3759 else
3760 ins_req(ins_idx, st1);
3761 }
3762 }
3763
3764 if (PrintCompilation && WizardMode)
3765 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
3766 old_subword, old_long, new_int, new_long);
3767 if (C->log() != NULL)
3768 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
3769 old_subword, old_long, new_int, new_long);
3770
3771 // Clean up any remaining occurrences of zmem:
3772 remove_extra_zeroes();
3773 }
3774
3775 // Explore forward from in(start) to find the first fully initialized
3776 // word, and return its offset. Skip groups of subword stores which
3777 // together initialize full words. If in(start) is itself part of a
3778 // fully initialized word, return the offset of in(start). If there
3779 // are no following full-word stores, or if something is fishy, return
3780 // a negative value.
3781 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
3782 int int_map = 0;
3783 intptr_t int_map_off = 0;
3784 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
3785
3786 for (uint i = start, limit = req(); i < limit; i++) {
3787 Node* st = in(i);
3788
3789 intptr_t st_off = get_store_offset(st, phase);
3790 if (st_off < 0) break; // return conservative answer
3791
3792 int st_size = st->as_Store()->memory_size();
3793 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
3794 return st_off; // we found a complete word init
3795 }
3796
3797 // update the map:
3798
3799 intptr_t this_int_off = align_size_down(st_off, BytesPerInt);
3800 if (this_int_off != int_map_off) {
3801 // reset the map:
3802 int_map = 0;
3803 int_map_off = this_int_off;
3804 }
3805
3806 int subword_off = st_off - this_int_off;
3807 int_map |= right_n_bits(st_size) << subword_off;
3808 if ((int_map & FULL_MAP) == FULL_MAP) {
3809 return this_int_off; // we found a complete word init
3810 }
3811
3812 // Did this store hit or cross the word boundary?
3813 intptr_t next_int_off = align_size_down(st_off + st_size, BytesPerInt);
3814 if (next_int_off == this_int_off + BytesPerInt) {
3815 // We passed the current int, without fully initializing it.
3816 int_map_off = next_int_off;
3817 int_map >>= BytesPerInt;
3818 } else if (next_int_off > this_int_off + BytesPerInt) {
3819 // We passed the current and next int.
3820 return this_int_off + BytesPerInt;
3821 }
3822 }
3823
3824 return -1;
3825 }
3826
3827
3828 // Called when the associated AllocateNode is expanded into CFG.
3829 // At this point, we may perform additional optimizations.
3830 // Linearize the stores by ascending offset, to make memory
3831 // activity as coherent as possible.
3832 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
3833 intptr_t header_size,
3834 Node* size_in_bytes,
3835 PhaseGVN* phase) {
3836 assert(!is_complete(), "not already complete");
3837 assert(stores_are_sane(phase), "");
3838 assert(allocation() != NULL, "must be present");
3839
3840 remove_extra_zeroes();
3841
3842 if (ReduceFieldZeroing || ReduceBulkZeroing)
3843 // reduce instruction count for common initialization patterns
3844 coalesce_subword_stores(header_size, size_in_bytes, phase);
3845
3846 Node* zmem = zero_memory(); // initially zero memory state
3847 Node* inits = zmem; // accumulating a linearized chain of inits
3848 #ifdef ASSERT
3849 intptr_t first_offset = allocation()->minimum_header_size();
3850 intptr_t last_init_off = first_offset; // previous init offset
3851 intptr_t last_init_end = first_offset; // previous init offset+size
3852 intptr_t last_tile_end = first_offset; // previous tile offset+size
3853 #endif
3854 intptr_t zeroes_done = header_size;
3855
3856 bool do_zeroing = true; // we might give up if inits are very sparse
3857 int big_init_gaps = 0; // how many large gaps have we seen?
3858
3859 if (ZeroTLAB) do_zeroing = false;
3860 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
3861
3862 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3863 Node* st = in(i);
3864 intptr_t st_off = get_store_offset(st, phase);
3865 if (st_off < 0)
3866 break; // unknown junk in the inits
3867 if (st->in(MemNode::Memory) != zmem)
3868 break; // complicated store chains somehow in list
3869
3870 int st_size = st->as_Store()->memory_size();
3871 intptr_t next_init_off = st_off + st_size;
3872
3873 if (do_zeroing && zeroes_done < next_init_off) {
3874 // See if this store needs a zero before it or under it.
3875 intptr_t zeroes_needed = st_off;
3876
3877 if (st_size < BytesPerInt) {
3878 // Look for subword stores which only partially initialize words.
3879 // If we find some, we must lay down some word-level zeroes first,
3880 // underneath the subword stores.
3881 //
3882 // Examples:
3883 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
3884 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
3885 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
3886 //
3887 // Note: coalesce_subword_stores may have already done this,
3888 // if it was prompted by constant non-zero subword initializers.
3889 // But this case can still arise with non-constant stores.
3890
3891 intptr_t next_full_store = find_next_fullword_store(i, phase);
3892
3893 // In the examples above:
3894 // in(i) p q r s x y z
3895 // st_off 12 13 14 15 12 13 14
3896 // st_size 1 1 1 1 1 1 1
3897 // next_full_s. 12 16 16 16 16 16 16
3898 // z's_done 12 16 16 16 12 16 12
3899 // z's_needed 12 16 16 16 16 16 16
3900 // zsize 0 0 0 0 4 0 4
3901 if (next_full_store < 0) {
3902 // Conservative tack: Zero to end of current word.
3903 zeroes_needed = align_size_up(zeroes_needed, BytesPerInt);
3904 } else {
3905 // Zero to beginning of next fully initialized word.
3906 // Or, don't zero at all, if we are already in that word.
3907 assert(next_full_store >= zeroes_needed, "must go forward");
3908 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
3909 zeroes_needed = next_full_store;
3910 }
3911 }
3912
3913 if (zeroes_needed > zeroes_done) {
3914 intptr_t zsize = zeroes_needed - zeroes_done;
3915 // Do some incremental zeroing on rawmem, in parallel with inits.
3916 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3917 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3918 zeroes_done, zeroes_needed,
3919 phase);
3920 zeroes_done = zeroes_needed;
3921 if (zsize > Matcher::init_array_short_size && ++big_init_gaps > 2)
3922 do_zeroing = false; // leave the hole, next time
3923 }
3924 }
3925
3926 // Collect the store and move on:
3927 st->set_req(MemNode::Memory, inits);
3928 inits = st; // put it on the linearized chain
3929 set_req(i, zmem); // unhook from previous position
3930
3931 if (zeroes_done == st_off)
3932 zeroes_done = next_init_off;
3933
3934 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
3935
3936 #ifdef ASSERT
3937 // Various order invariants. Weaker than stores_are_sane because
3938 // a large constant tile can be filled in by smaller non-constant stores.
3939 assert(st_off >= last_init_off, "inits do not reverse");
3940 last_init_off = st_off;
3941 const Type* val = NULL;
3942 if (st_size >= BytesPerInt &&
3943 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
3944 (int)val->basic_type() < (int)T_OBJECT) {
3945 assert(st_off >= last_tile_end, "tiles do not overlap");
3946 assert(st_off >= last_init_end, "tiles do not overwrite inits");
3947 last_tile_end = MAX2(last_tile_end, next_init_off);
3948 } else {
3949 intptr_t st_tile_end = align_size_up(next_init_off, BytesPerLong);
3950 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
3951 assert(st_off >= last_init_end, "inits do not overlap");
3952 last_init_end = next_init_off; // it's a non-tile
3953 }
3954 #endif //ASSERT
3955 }
3956
3957 remove_extra_zeroes(); // clear out all the zmems left over
3958 add_req(inits);
3959
3960 if (!ZeroTLAB) {
3961 // If anything remains to be zeroed, zero it all now.
3962 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3963 // if it is the last unused 4 bytes of an instance, forget about it
3964 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
3965 if (zeroes_done + BytesPerLong >= size_limit) {
3966 assert(allocation() != NULL, "");
3967 if (allocation()->Opcode() == Op_Allocate) {
3968 Node* klass_node = allocation()->in(AllocateNode::KlassNode);
3969 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass();
3970 if (zeroes_done == k->layout_helper())
3971 zeroes_done = size_limit;
3972 }
3973 }
3974 if (zeroes_done < size_limit) {
3975 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3976 zeroes_done, size_in_bytes, phase);
3977 }
3978 }
3979
3980 set_complete(phase);
3981 return rawmem;
3982 }
3983
3984
3985 #ifdef ASSERT
3986 bool InitializeNode::stores_are_sane(PhaseTransform* phase) {
3987 if (is_complete())
3988 return true; // stores could be anything at this point
3989 assert(allocation() != NULL, "must be present");
3990 intptr_t last_off = allocation()->minimum_header_size();
3991 for (uint i = InitializeNode::RawStores; i < req(); i++) {
3992 Node* st = in(i);
3993 intptr_t st_off = get_store_offset(st, phase);
3994 if (st_off < 0) continue; // ignore dead garbage
3995 if (last_off > st_off) {
3996 tty->print_cr("*** bad store offset at %d: " INTX_FORMAT " > " INTX_FORMAT, i, last_off, st_off);
3997 this->dump(2);
3998 assert(false, "ascending store offsets");
3999 return false;
4000 }
4001 last_off = st_off + st->as_Store()->memory_size();
4002 }
4003 return true;
4004 }
4005 #endif //ASSERT
4006
4007
4008
4009
4010 //============================MergeMemNode=====================================
4011 //
4012 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
4013 // contributing store or call operations. Each contributor provides the memory
4014 // state for a particular "alias type" (see Compile::alias_type). For example,
4015 // if a MergeMem has an input X for alias category #6, then any memory reference
4016 // to alias category #6 may use X as its memory state input, as an exact equivalent
4017 // to using the MergeMem as a whole.
4018 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
4019 //
4020 // (Here, the <N> notation gives the index of the relevant adr_type.)
4021 //
4022 // In one special case (and more cases in the future), alias categories overlap.
4023 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
4024 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
4025 // it is exactly equivalent to that state W:
4026 // MergeMem(<Bot>: W) <==> W
4027 //
4028 // Usually, the merge has more than one input. In that case, where inputs
4029 // overlap (i.e., one is Bot), the narrower alias type determines the memory
4030 // state for that type, and the wider alias type (Bot) fills in everywhere else:
4031 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
4032 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
4033 //
4034 // A merge can take a "wide" memory state as one of its narrow inputs.
4035 // This simply means that the merge observes out only the relevant parts of
4036 // the wide input. That is, wide memory states arriving at narrow merge inputs
4037 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
4038 //
4039 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
4040 // and that memory slices "leak through":
4041 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
4042 //
4043 // But, in such a cascade, repeated memory slices can "block the leak":
4044 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
4045 //
4046 // In the last example, Y is not part of the combined memory state of the
4047 // outermost MergeMem. The system must, of course, prevent unschedulable
4048 // memory states from arising, so you can be sure that the state Y is somehow
4049 // a precursor to state Y'.
4050 //
4051 //
4052 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
4053 // of each MergeMemNode array are exactly the numerical alias indexes, including
4054 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
4055 // Compile::alias_type (and kin) produce and manage these indexes.
4056 //
4057 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
4058 // (Note that this provides quick access to the top node inside MergeMem methods,
4059 // without the need to reach out via TLS to Compile::current.)
4060 //
4061 // As a consequence of what was just described, a MergeMem that represents a full
4062 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
4063 // containing all alias categories.
4064 //
4065 // MergeMem nodes never (?) have control inputs, so in(0) is NULL.
4066 //
4067 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
4068 // a memory state for the alias type <N>, or else the top node, meaning that
4069 // there is no particular input for that alias type. Note that the length of
4070 // a MergeMem is variable, and may be extended at any time to accommodate new
4071 // memory states at larger alias indexes. When merges grow, they are of course
4072 // filled with "top" in the unused in() positions.
4073 //
4074 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
4075 // (Top was chosen because it works smoothly with passes like GCM.)
4076 //
4077 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
4078 // the type of random VM bits like TLS references.) Since it is always the
4079 // first non-Bot memory slice, some low-level loops use it to initialize an
4080 // index variable: for (i = AliasIdxRaw; i < req(); i++).
4081 //
4082 //
4083 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
4084 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
4085 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
4086 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
4087 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
4088 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
4089 //
4090 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
4091 // really that different from the other memory inputs. An abbreviation called
4092 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
4093 //
4094 //
4095 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
4096 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
4097 // that "emerges though" the base memory will be marked as excluding the alias types
4098 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
4099 //
4100 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
4101 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
4102 //
4103 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
4104 // (It is currently unimplemented.) As you can see, the resulting merge is
4105 // actually a disjoint union of memory states, rather than an overlay.
4106 //
4107
4108 //------------------------------MergeMemNode-----------------------------------
4109 Node* MergeMemNode::make_empty_memory() {
4110 Node* empty_memory = (Node*) Compile::current()->top();
4111 assert(empty_memory->is_top(), "correct sentinel identity");
4112 return empty_memory;
4113 }
4114
4115 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
4116 init_class_id(Class_MergeMem);
4117 // all inputs are nullified in Node::Node(int)
4118 // set_input(0, NULL); // no control input
4119
4120 // Initialize the edges uniformly to top, for starters.
4121 Node* empty_mem = make_empty_memory();
4122 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
4123 init_req(i,empty_mem);
4124 }
4125 assert(empty_memory() == empty_mem, "");
4126
4127 if( new_base != NULL && new_base->is_MergeMem() ) {
4128 MergeMemNode* mdef = new_base->as_MergeMem();
4129 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
4130 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
4131 mms.set_memory(mms.memory2());
4132 }
4133 assert(base_memory() == mdef->base_memory(), "");
4134 } else {
4135 set_base_memory(new_base);
4136 }
4137 }
4138
4139 // Make a new, untransformed MergeMem with the same base as 'mem'.
4140 // If mem is itself a MergeMem, populate the result with the same edges.
4141 MergeMemNode* MergeMemNode::make(Node* mem) {
4142 return new MergeMemNode(mem);
4143 }
4144
4145 //------------------------------cmp--------------------------------------------
4146 uint MergeMemNode::hash() const { return NO_HASH; }
4147 uint MergeMemNode::cmp( const Node &n ) const {
4148 return (&n == this); // Always fail except on self
4149 }
4150
4151 //------------------------------Identity---------------------------------------
4152 Node* MergeMemNode::Identity(PhaseTransform *phase) {
4153 // Identity if this merge point does not record any interesting memory
4154 // disambiguations.
4155 Node* base_mem = base_memory();
4156 Node* empty_mem = empty_memory();
4157 if (base_mem != empty_mem) { // Memory path is not dead?
4158 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4159 Node* mem = in(i);
4160 if (mem != empty_mem && mem != base_mem) {
4161 return this; // Many memory splits; no change
4162 }
4163 }
4164 }
4165 return base_mem; // No memory splits; ID on the one true input
4166 }
4167
4168 //------------------------------Ideal------------------------------------------
4169 // This method is invoked recursively on chains of MergeMem nodes
4170 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4171 // Remove chain'd MergeMems
4172 //
4173 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
4174 // relative to the "in(Bot)". Since we are patching both at the same time,
4175 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
4176 // but rewrite each "in(i)" relative to the new "in(Bot)".
4177 Node *progress = NULL;
4178
4179
4180 Node* old_base = base_memory();
4181 Node* empty_mem = empty_memory();
4182 if (old_base == empty_mem)
4183 return NULL; // Dead memory path.
4184
4185 MergeMemNode* old_mbase;
4186 if (old_base != NULL && old_base->is_MergeMem())
4187 old_mbase = old_base->as_MergeMem();
4188 else
4189 old_mbase = NULL;
4190 Node* new_base = old_base;
4191
4192 // simplify stacked MergeMems in base memory
4193 if (old_mbase) new_base = old_mbase->base_memory();
4194
4195 // the base memory might contribute new slices beyond my req()
4196 if (old_mbase) grow_to_match(old_mbase);
4197
4198 // Look carefully at the base node if it is a phi.
4199 PhiNode* phi_base;
4200 if (new_base != NULL && new_base->is_Phi())
4201 phi_base = new_base->as_Phi();
4202 else
4203 phi_base = NULL;
4204
4205 Node* phi_reg = NULL;
4206 uint phi_len = (uint)-1;
4207 if (phi_base != NULL && !phi_base->is_copy()) {
4208 // do not examine phi if degraded to a copy
4209 phi_reg = phi_base->region();
4210 phi_len = phi_base->req();
4211 // see if the phi is unfinished
4212 for (uint i = 1; i < phi_len; i++) {
4213 if (phi_base->in(i) == NULL) {
4214 // incomplete phi; do not look at it yet!
4215 phi_reg = NULL;
4216 phi_len = (uint)-1;
4217 break;
4218 }
4219 }
4220 }
4221
4222 // Note: We do not call verify_sparse on entry, because inputs
4223 // can normalize to the base_memory via subsume_node or similar
4224 // mechanisms. This method repairs that damage.
4225
4226 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
4227
4228 // Look at each slice.
4229 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4230 Node* old_in = in(i);
4231 // calculate the old memory value
4232 Node* old_mem = old_in;
4233 if (old_mem == empty_mem) old_mem = old_base;
4234 assert(old_mem == memory_at(i), "");
4235
4236 // maybe update (reslice) the old memory value
4237
4238 // simplify stacked MergeMems
4239 Node* new_mem = old_mem;
4240 MergeMemNode* old_mmem;
4241 if (old_mem != NULL && old_mem->is_MergeMem())
4242 old_mmem = old_mem->as_MergeMem();
4243 else
4244 old_mmem = NULL;
4245 if (old_mmem == this) {
4246 // This can happen if loops break up and safepoints disappear.
4247 // A merge of BotPtr (default) with a RawPtr memory derived from a
4248 // safepoint can be rewritten to a merge of the same BotPtr with
4249 // the BotPtr phi coming into the loop. If that phi disappears
4250 // also, we can end up with a self-loop of the mergemem.
4251 // In general, if loops degenerate and memory effects disappear,
4252 // a mergemem can be left looking at itself. This simply means
4253 // that the mergemem's default should be used, since there is
4254 // no longer any apparent effect on this slice.
4255 // Note: If a memory slice is a MergeMem cycle, it is unreachable
4256 // from start. Update the input to TOP.
4257 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
4258 }
4259 else if (old_mmem != NULL) {
4260 new_mem = old_mmem->memory_at(i);
4261 }
4262 // else preceding memory was not a MergeMem
4263
4264 // replace equivalent phis (unfortunately, they do not GVN together)
4265 if (new_mem != NULL && new_mem != new_base &&
4266 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) {
4267 if (new_mem->is_Phi()) {
4268 PhiNode* phi_mem = new_mem->as_Phi();
4269 for (uint i = 1; i < phi_len; i++) {
4270 if (phi_base->in(i) != phi_mem->in(i)) {
4271 phi_mem = NULL;
4272 break;
4273 }
4274 }
4275 if (phi_mem != NULL) {
4276 // equivalent phi nodes; revert to the def
4277 new_mem = new_base;
4278 }
4279 }
4280 }
4281
4282 // maybe store down a new value
4283 Node* new_in = new_mem;
4284 if (new_in == new_base) new_in = empty_mem;
4285
4286 if (new_in != old_in) {
4287 // Warning: Do not combine this "if" with the previous "if"
4288 // A memory slice might have be be rewritten even if it is semantically
4289 // unchanged, if the base_memory value has changed.
4290 set_req(i, new_in);
4291 progress = this; // Report progress
4292 }
4293 }
4294
4295 if (new_base != old_base) {
4296 set_req(Compile::AliasIdxBot, new_base);
4297 // Don't use set_base_memory(new_base), because we need to update du.
4298 assert(base_memory() == new_base, "");
4299 progress = this;
4300 }
4301
4302 if( base_memory() == this ) {
4303 // a self cycle indicates this memory path is dead
4304 set_req(Compile::AliasIdxBot, empty_mem);
4305 }
4306
4307 // Resolve external cycles by calling Ideal on a MergeMem base_memory
4308 // Recursion must occur after the self cycle check above
4309 if( base_memory()->is_MergeMem() ) {
4310 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
4311 Node *m = phase->transform(new_mbase); // Rollup any cycles
4312 if( m != NULL && (m->is_top() ||
4313 m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem) ) {
4314 // propagate rollup of dead cycle to self
4315 set_req(Compile::AliasIdxBot, empty_mem);
4316 }
4317 }
4318
4319 if( base_memory() == empty_mem ) {
4320 progress = this;
4321 // Cut inputs during Parse phase only.
4322 // During Optimize phase a dead MergeMem node will be subsumed by Top.
4323 if( !can_reshape ) {
4324 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4325 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
4326 }
4327 }
4328 }
4329
4330 if( !progress && base_memory()->is_Phi() && can_reshape ) {
4331 // Check if PhiNode::Ideal's "Split phis through memory merges"
4332 // transform should be attempted. Look for this->phi->this cycle.
4333 uint merge_width = req();
4334 if (merge_width > Compile::AliasIdxRaw) {
4335 PhiNode* phi = base_memory()->as_Phi();
4336 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
4337 if (phi->in(i) == this) {
4338 phase->is_IterGVN()->_worklist.push(phi);
4339 break;
4340 }
4341 }
4342 }
4343 }
4344
4345 assert(progress || verify_sparse(), "please, no dups of base");
4346 return progress;
4347 }
4348
4349 //-------------------------set_base_memory-------------------------------------
4350 void MergeMemNode::set_base_memory(Node *new_base) {
4351 Node* empty_mem = empty_memory();
4352 set_req(Compile::AliasIdxBot, new_base);
4353 assert(memory_at(req()) == new_base, "must set default memory");
4354 // Clear out other occurrences of new_base:
4355 if (new_base != empty_mem) {
4356 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4357 if (in(i) == new_base) set_req(i, empty_mem);
4358 }
4359 }
4360 }
4361
4362 //------------------------------out_RegMask------------------------------------
4363 const RegMask &MergeMemNode::out_RegMask() const {
4364 return RegMask::Empty;
4365 }
4366
4367 //------------------------------dump_spec--------------------------------------
4368 #ifndef PRODUCT
4369 void MergeMemNode::dump_spec(outputStream *st) const {
4370 st->print(" {");
4371 Node* base_mem = base_memory();
4372 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
4373 Node* mem = (in(i) != NULL) ? memory_at(i) : base_mem;
4374 if (mem == base_mem) { st->print(" -"); continue; }
4375 st->print( " N%d:", mem->_idx );
4376 Compile::current()->get_adr_type(i)->dump_on(st);
4377 }
4378 st->print(" }");
4379 }
4380 #endif // !PRODUCT
4381
4382
4383 #ifdef ASSERT
4384 static bool might_be_same(Node* a, Node* b) {
4385 if (a == b) return true;
4386 if (!(a->is_Phi() || b->is_Phi())) return false;
4387 // phis shift around during optimization
4388 return true; // pretty stupid...
4389 }
4390
4391 // verify a narrow slice (either incoming or outgoing)
4392 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
4393 if (!VerifyAliases) return; // don't bother to verify unless requested
4394 if (is_error_reported()) return; // muzzle asserts when debugging an error
4395 if (Node::in_dump()) return; // muzzle asserts when printing
4396 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
4397 assert(n != NULL, "");
4398 // Elide intervening MergeMem's
4399 while (n->is_MergeMem()) {
4400 n = n->as_MergeMem()->memory_at(alias_idx);
4401 }
4402 Compile* C = Compile::current();
4403 const TypePtr* n_adr_type = n->adr_type();
4404 if (n == m->empty_memory()) {
4405 // Implicit copy of base_memory()
4406 } else if (n_adr_type != TypePtr::BOTTOM) {
4407 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type");
4408 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
4409 } else {
4410 // A few places like make_runtime_call "know" that VM calls are narrow,
4411 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
4412 bool expected_wide_mem = false;
4413 if (n == m->base_memory()) {
4414 expected_wide_mem = true;
4415 } else if (alias_idx == Compile::AliasIdxRaw ||
4416 n == m->memory_at(Compile::AliasIdxRaw)) {
4417 expected_wide_mem = true;
4418 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
4419 // memory can "leak through" calls on channels that
4420 // are write-once. Allow this also.
4421 expected_wide_mem = true;
4422 }
4423 assert(expected_wide_mem, "expected narrow slice replacement");
4424 }
4425 }
4426 #else // !ASSERT
4427 #define verify_memory_slice(m,i,n) (void)(0) // PRODUCT version is no-op
4428 #endif
4429
4430
4431 //-----------------------------memory_at---------------------------------------
4432 Node* MergeMemNode::memory_at(uint alias_idx) const {
4433 assert(alias_idx >= Compile::AliasIdxRaw ||
4434 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0,
4435 "must avoid base_memory and AliasIdxTop");
4436
4437 // Otherwise, it is a narrow slice.
4438 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
4439 Compile *C = Compile::current();
4440 if (is_empty_memory(n)) {
4441 // the array is sparse; empty slots are the "top" node
4442 n = base_memory();
4443 assert(Node::in_dump()
4444 || n == NULL || n->bottom_type() == Type::TOP
4445 || n->adr_type() == NULL // address is TOP
4446 || n->adr_type() == TypePtr::BOTTOM
4447 || n->adr_type() == TypeRawPtr::BOTTOM
4448 || Compile::current()->AliasLevel() == 0,
4449 "must be a wide memory");
4450 // AliasLevel == 0 if we are organizing the memory states manually.
4451 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
4452 } else {
4453 // make sure the stored slice is sane
4454 #ifdef ASSERT
4455 if (is_error_reported() || Node::in_dump()) {
4456 } else if (might_be_same(n, base_memory())) {
4457 // Give it a pass: It is a mostly harmless repetition of the base.
4458 // This can arise normally from node subsumption during optimization.
4459 } else {
4460 verify_memory_slice(this, alias_idx, n);
4461 }
4462 #endif
4463 }
4464 return n;
4465 }
4466
4467 //---------------------------set_memory_at-------------------------------------
4468 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
4469 verify_memory_slice(this, alias_idx, n);
4470 Node* empty_mem = empty_memory();
4471 if (n == base_memory()) n = empty_mem; // collapse default
4472 uint need_req = alias_idx+1;
4473 if (req() < need_req) {
4474 if (n == empty_mem) return; // already the default, so do not grow me
4475 // grow the sparse array
4476 do {
4477 add_req(empty_mem);
4478 } while (req() < need_req);
4479 }
4480 set_req( alias_idx, n );
4481 }
4482
4483
4484
4485 //--------------------------iteration_setup------------------------------------
4486 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
4487 if (other != NULL) {
4488 grow_to_match(other);
4489 // invariant: the finite support of mm2 is within mm->req()
4490 #ifdef ASSERT
4491 for (uint i = req(); i < other->req(); i++) {
4492 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
4493 }
4494 #endif
4495 }
4496 // Replace spurious copies of base_memory by top.
4497 Node* base_mem = base_memory();
4498 if (base_mem != NULL && !base_mem->is_top()) {
4499 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
4500 if (in(i) == base_mem)
4501 set_req(i, empty_memory());
4502 }
4503 }
4504 }
4505
4506 //---------------------------grow_to_match-------------------------------------
4507 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
4508 Node* empty_mem = empty_memory();
4509 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
4510 // look for the finite support of the other memory
4511 for (uint i = other->req(); --i >= req(); ) {
4512 if (other->in(i) != empty_mem) {
4513 uint new_len = i+1;
4514 while (req() < new_len) add_req(empty_mem);
4515 break;
4516 }
4517 }
4518 }
4519
4520 //---------------------------verify_sparse-------------------------------------
4521 #ifndef PRODUCT
4522 bool MergeMemNode::verify_sparse() const {
4523 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
4524 Node* base_mem = base_memory();
4525 // The following can happen in degenerate cases, since empty==top.
4526 if (is_empty_memory(base_mem)) return true;
4527 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4528 assert(in(i) != NULL, "sane slice");
4529 if (in(i) == base_mem) return false; // should have been the sentinel value!
4530 }
4531 return true;
4532 }
4533
4534 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
4535 Node* n;
4536 n = mm->in(idx);
4537 if (mem == n) return true; // might be empty_memory()
4538 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
4539 if (mem == n) return true;
4540 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) {
4541 if (mem == n) return true;
4542 if (n == NULL) break;
4543 }
4544 return false;
4545 }
4546 #endif // !PRODUCT