1 /*
2 * Copyright (c) 1997, 2012, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/systemDictionary.hpp"
27 #include "compiler/compileLog.hpp"
28 #include "memory/allocation.inline.hpp"
29 #include "oops/objArrayKlass.hpp"
30 #include "opto/addnode.hpp"
31 #include "opto/cfgnode.hpp"
32 #include "opto/compile.hpp"
33 #include "opto/connode.hpp"
34 #include "opto/loopnode.hpp"
35 #include "opto/machnode.hpp"
36 #include "opto/matcher.hpp"
37 #include "opto/memnode.hpp"
38 #include "opto/mulnode.hpp"
39 #include "opto/phaseX.hpp"
40 #include "opto/regmask.hpp"
41
42 // Portions of code courtesy of Clifford Click
43
44 // Optimization - Graph Style
45
46 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st);
47
48 //=============================================================================
49 uint MemNode::size_of() const { return sizeof(*this); }
50
51 const TypePtr *MemNode::adr_type() const {
52 Node* adr = in(Address);
53 const TypePtr* cross_check = NULL;
54 DEBUG_ONLY(cross_check = _adr_type);
55 return calculate_adr_type(adr->bottom_type(), cross_check);
56 }
57
58 #ifndef PRODUCT
59 void MemNode::dump_spec(outputStream *st) const {
60 if (in(Address) == NULL) return; // node is dead
61 #ifndef ASSERT
62 // fake the missing field
63 const TypePtr* _adr_type = NULL;
64 if (in(Address) != NULL)
65 _adr_type = in(Address)->bottom_type()->isa_ptr();
66 #endif
67 dump_adr_type(this, _adr_type, st);
68
69 Compile* C = Compile::current();
70 if( C->alias_type(_adr_type)->is_volatile() )
71 st->print(" Volatile!");
72 }
73
74 void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) {
75 st->print(" @");
76 if (adr_type == NULL) {
77 st->print("NULL");
78 } else {
79 adr_type->dump_on(st);
80 Compile* C = Compile::current();
81 Compile::AliasType* atp = NULL;
82 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type);
83 if (atp == NULL)
84 st->print(", idx=?\?;");
85 else if (atp->index() == Compile::AliasIdxBot)
86 st->print(", idx=Bot;");
87 else if (atp->index() == Compile::AliasIdxTop)
88 st->print(", idx=Top;");
89 else if (atp->index() == Compile::AliasIdxRaw)
90 st->print(", idx=Raw;");
91 else {
92 ciField* field = atp->field();
93 if (field) {
94 st->print(", name=");
95 field->print_name_on(st);
96 }
97 st->print(", idx=%d;", atp->index());
98 }
99 }
100 }
101
102 extern void print_alias_types();
103
104 #endif
105
106 Node *MemNode::optimize_simple_memory_chain(Node *mchain, const TypePtr *t_adr, PhaseGVN *phase) {
107 const TypeOopPtr *tinst = t_adr->isa_oopptr();
108 if (tinst == NULL || !tinst->is_known_instance_field())
109 return mchain; // don't try to optimize non-instance types
110 uint instance_id = tinst->instance_id();
111 Node *start_mem = phase->C->start()->proj_out(TypeFunc::Memory);
112 Node *prev = NULL;
113 Node *result = mchain;
114 while (prev != result) {
115 prev = result;
116 if (result == start_mem)
117 break; // hit one of our sentinels
118 // skip over a call which does not affect this memory slice
119 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {
120 Node *proj_in = result->in(0);
121 if (proj_in->is_Allocate() && proj_in->_idx == instance_id) {
122 break; // hit one of our sentinels
123 } else if (proj_in->is_Call()) {
124 CallNode *call = proj_in->as_Call();
125 if (!call->may_modify(t_adr, phase)) {
126 result = call->in(TypeFunc::Memory);
127 }
128 } else if (proj_in->is_Initialize()) {
129 AllocateNode* alloc = proj_in->as_Initialize()->allocation();
130 // Stop if this is the initialization for the object instance which
131 // which contains this memory slice, otherwise skip over it.
132 if (alloc != NULL && alloc->_idx != instance_id) {
133 result = proj_in->in(TypeFunc::Memory);
134 }
135 } else if (proj_in->is_MemBar()) {
136 result = proj_in->in(TypeFunc::Memory);
137 } else {
138 assert(false, "unexpected projection");
139 }
140 } else if (result->is_ClearArray()) {
141 if (!ClearArrayNode::step_through(&result, instance_id, phase)) {
142 // Can not bypass initialization of the instance
143 // we are looking for.
144 break;
145 }
146 // Otherwise skip it (the call updated 'result' value).
147 } else if (result->is_MergeMem()) {
148 result = step_through_mergemem(phase, result->as_MergeMem(), t_adr, NULL, tty);
149 }
150 }
151 return result;
152 }
153
154 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, PhaseGVN *phase) {
155 const TypeOopPtr *t_oop = t_adr->isa_oopptr();
156 bool is_instance = (t_oop != NULL) && t_oop->is_known_instance_field();
157 PhaseIterGVN *igvn = phase->is_IterGVN();
158 Node *result = mchain;
159 result = optimize_simple_memory_chain(result, t_adr, phase);
160 if (is_instance && igvn != NULL && result->is_Phi()) {
161 PhiNode *mphi = result->as_Phi();
162 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
163 const TypePtr *t = mphi->adr_type();
164 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
165 t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
166 t->is_oopptr()->cast_to_exactness(true)
167 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
168 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop) {
169 // clone the Phi with our address type
170 result = mphi->split_out_instance(t_adr, igvn);
171 } else {
172 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain");
173 }
174 }
175 return result;
176 }
177
178 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) {
179 uint alias_idx = phase->C->get_alias_index(tp);
180 Node *mem = mmem;
181 #ifdef ASSERT
182 {
183 // Check that current type is consistent with the alias index used during graph construction
184 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
185 bool consistent = adr_check == NULL || adr_check->empty() ||
186 phase->C->must_alias(adr_check, alias_idx );
187 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
188 if( !consistent && adr_check != NULL && !adr_check->empty() &&
189 tp->isa_aryptr() && tp->offset() == Type::OffsetBot &&
190 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot &&
191 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() ||
192 adr_check->offset() == oopDesc::klass_offset_in_bytes() ||
193 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) {
194 // don't assert if it is dead code.
195 consistent = true;
196 }
197 if( !consistent ) {
198 st->print("alias_idx==%d, adr_check==", alias_idx);
199 if( adr_check == NULL ) {
200 st->print("NULL");
201 } else {
202 adr_check->dump();
203 }
204 st->cr();
205 print_alias_types();
206 assert(consistent, "adr_check must match alias idx");
207 }
208 }
209 #endif
210 // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally
211 // means an array I have not precisely typed yet. Do not do any
212 // alias stuff with it any time soon.
213 const TypeOopPtr *toop = tp->isa_oopptr();
214 if( tp->base() != Type::AnyPtr &&
215 !(toop &&
216 toop->klass() != NULL &&
217 toop->klass()->is_java_lang_Object() &&
218 toop->offset() == Type::OffsetBot) ) {
219 // compress paths and change unreachable cycles to TOP
220 // If not, we can update the input infinitely along a MergeMem cycle
221 // Equivalent code in PhiNode::Ideal
222 Node* m = phase->transform(mmem);
223 // If transformed to a MergeMem, get the desired slice
224 // Otherwise the returned node represents memory for every slice
225 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
226 // Update input if it is progress over what we have now
227 }
228 return mem;
229 }
230
231 //--------------------------Ideal_common---------------------------------------
232 // Look for degenerate control and memory inputs. Bypass MergeMem inputs.
233 // Unhook non-raw memories from complete (macro-expanded) initializations.
234 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
235 // If our control input is a dead region, kill all below the region
236 Node *ctl = in(MemNode::Control);
237 if (ctl && remove_dead_region(phase, can_reshape))
238 return this;
239 ctl = in(MemNode::Control);
240 // Don't bother trying to transform a dead node
241 if (ctl && ctl->is_top()) return NodeSentinel;
242
243 PhaseIterGVN *igvn = phase->is_IterGVN();
244 // Wait if control on the worklist.
245 if (ctl && can_reshape && igvn != NULL) {
246 Node* bol = NULL;
247 Node* cmp = NULL;
248 if (ctl->in(0)->is_If()) {
249 assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity");
250 bol = ctl->in(0)->in(1);
251 if (bol->is_Bool())
252 cmp = ctl->in(0)->in(1)->in(1);
253 }
254 if (igvn->_worklist.member(ctl) ||
255 (bol != NULL && igvn->_worklist.member(bol)) ||
256 (cmp != NULL && igvn->_worklist.member(cmp)) ) {
257 // This control path may be dead.
258 // Delay this memory node transformation until the control is processed.
259 phase->is_IterGVN()->_worklist.push(this);
260 return NodeSentinel; // caller will return NULL
261 }
262 }
263 // Ignore if memory is dead, or self-loop
264 Node *mem = in(MemNode::Memory);
265 if (phase->type( mem ) == Type::TOP) return NodeSentinel; // caller will return NULL
266 assert(mem != this, "dead loop in MemNode::Ideal");
267
268 if (can_reshape && igvn != NULL && igvn->_worklist.member(mem)) {
269 // This memory slice may be dead.
270 // Delay this mem node transformation until the memory is processed.
271 phase->is_IterGVN()->_worklist.push(this);
272 return NodeSentinel; // caller will return NULL
273 }
274
275 Node *address = in(MemNode::Address);
276 const Type *t_adr = phase->type(address);
277 if (t_adr == Type::TOP) return NodeSentinel; // caller will return NULL
278
279 if (can_reshape && igvn != NULL &&
280 (igvn->_worklist.member(address) ||
281 igvn->_worklist.size() > 0 && (t_adr != adr_type())) ) {
282 // The address's base and type may change when the address is processed.
283 // Delay this mem node transformation until the address is processed.
284 phase->is_IterGVN()->_worklist.push(this);
285 return NodeSentinel; // caller will return NULL
286 }
287
288 // Do NOT remove or optimize the next lines: ensure a new alias index
289 // is allocated for an oop pointer type before Escape Analysis.
290 // Note: C++ will not remove it since the call has side effect.
291 if (t_adr->isa_oopptr()) {
292 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr());
293 }
294
295 #ifdef ASSERT
296 Node* base = NULL;
297 if (address->is_AddP())
298 base = address->in(AddPNode::Base);
299 if (base != NULL && phase->type(base)->higher_equal(TypePtr::NULL_PTR) &&
300 !t_adr->isa_rawptr()) {
301 // Note: raw address has TOP base and top->higher_equal(TypePtr::NULL_PTR) is true.
302 Compile* C = phase->C;
303 tty->cr();
304 tty->print_cr("===== NULL+offs not RAW address =====");
305 if (C->is_dead_node(this->_idx)) tty->print_cr("'this' is dead");
306 if ((ctl != NULL) && C->is_dead_node(ctl->_idx)) tty->print_cr("'ctl' is dead");
307 if (C->is_dead_node(mem->_idx)) tty->print_cr("'mem' is dead");
308 if (C->is_dead_node(address->_idx)) tty->print_cr("'address' is dead");
309 if (C->is_dead_node(base->_idx)) tty->print_cr("'base' is dead");
310 tty->cr();
311 base->dump(1);
312 tty->cr();
313 this->dump(2);
314 tty->print("this->adr_type(): "); adr_type()->dump(); tty->cr();
315 tty->print("phase->type(address): "); t_adr->dump(); tty->cr();
316 tty->print("phase->type(base): "); phase->type(address)->dump(); tty->cr();
317 tty->cr();
318 }
319 assert(base == NULL || t_adr->isa_rawptr() ||
320 !phase->type(base)->higher_equal(TypePtr::NULL_PTR), "NULL+offs not RAW address?");
321 #endif
322
323 // Avoid independent memory operations
324 Node* old_mem = mem;
325
326 // The code which unhooks non-raw memories from complete (macro-expanded)
327 // initializations was removed. After macro-expansion all stores catched
328 // by Initialize node became raw stores and there is no information
329 // which memory slices they modify. So it is unsafe to move any memory
330 // operation above these stores. Also in most cases hooked non-raw memories
331 // were already unhooked by using information from detect_ptr_independence()
332 // and find_previous_store().
333
334 if (mem->is_MergeMem()) {
335 MergeMemNode* mmem = mem->as_MergeMem();
336 const TypePtr *tp = t_adr->is_ptr();
337
338 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
339 }
340
341 if (mem != old_mem) {
342 set_req(MemNode::Memory, mem);
343 if (can_reshape && old_mem->outcnt() == 0) {
344 igvn->_worklist.push(old_mem);
345 }
346 if (phase->type( mem ) == Type::TOP) return NodeSentinel;
347 return this;
348 }
349
350 // let the subclass continue analyzing...
351 return NULL;
352 }
353
354 // Helper function for proving some simple control dominations.
355 // Attempt to prove that all control inputs of 'dom' dominate 'sub'.
356 // Already assumes that 'dom' is available at 'sub', and that 'sub'
357 // is not a constant (dominated by the method's StartNode).
358 // Used by MemNode::find_previous_store to prove that the
359 // control input of a memory operation predates (dominates)
360 // an allocation it wants to look past.
361 bool MemNode::all_controls_dominate(Node* dom, Node* sub) {
362 if (dom == NULL || dom->is_top() || sub == NULL || sub->is_top())
363 return false; // Conservative answer for dead code
364
365 // Check 'dom'. Skip Proj and CatchProj nodes.
366 dom = dom->find_exact_control(dom);
367 if (dom == NULL || dom->is_top())
368 return false; // Conservative answer for dead code
369
370 if (dom == sub) {
371 // For the case when, for example, 'sub' is Initialize and the original
372 // 'dom' is Proj node of the 'sub'.
373 return false;
374 }
375
376 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub)
377 return true;
378
379 // 'dom' dominates 'sub' if its control edge and control edges
380 // of all its inputs dominate or equal to sub's control edge.
381
382 // Currently 'sub' is either Allocate, Initialize or Start nodes.
383 // Or Region for the check in LoadNode::Ideal();
384 // 'sub' should have sub->in(0) != NULL.
385 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() ||
386 sub->is_Region(), "expecting only these nodes");
387
388 // Get control edge of 'sub'.
389 Node* orig_sub = sub;
390 sub = sub->find_exact_control(sub->in(0));
391 if (sub == NULL || sub->is_top())
392 return false; // Conservative answer for dead code
393
394 assert(sub->is_CFG(), "expecting control");
395
396 if (sub == dom)
397 return true;
398
399 if (sub->is_Start() || sub->is_Root())
400 return false;
401
402 {
403 // Check all control edges of 'dom'.
404
405 ResourceMark rm;
406 Arena* arena = Thread::current()->resource_area();
407 Node_List nlist(arena);
408 Unique_Node_List dom_list(arena);
409
410 dom_list.push(dom);
411 bool only_dominating_controls = false;
412
413 for (uint next = 0; next < dom_list.size(); next++) {
414 Node* n = dom_list.at(next);
415 if (n == orig_sub)
416 return false; // One of dom's inputs dominated by sub.
417 if (!n->is_CFG() && n->pinned()) {
418 // Check only own control edge for pinned non-control nodes.
419 n = n->find_exact_control(n->in(0));
420 if (n == NULL || n->is_top())
421 return false; // Conservative answer for dead code
422 assert(n->is_CFG(), "expecting control");
423 dom_list.push(n);
424 } else if (n->is_Con() || n->is_Start() || n->is_Root()) {
425 only_dominating_controls = true;
426 } else if (n->is_CFG()) {
427 if (n->dominates(sub, nlist))
428 only_dominating_controls = true;
429 else
430 return false;
431 } else {
432 // First, own control edge.
433 Node* m = n->find_exact_control(n->in(0));
434 if (m != NULL) {
435 if (m->is_top())
436 return false; // Conservative answer for dead code
437 dom_list.push(m);
438 }
439 // Now, the rest of edges.
440 uint cnt = n->req();
441 for (uint i = 1; i < cnt; i++) {
442 m = n->find_exact_control(n->in(i));
443 if (m == NULL || m->is_top())
444 continue;
445 dom_list.push(m);
446 }
447 }
448 }
449 return only_dominating_controls;
450 }
451 }
452
453 //---------------------detect_ptr_independence---------------------------------
454 // Used by MemNode::find_previous_store to prove that two base
455 // pointers are never equal.
456 // The pointers are accompanied by their associated allocations,
457 // if any, which have been previously discovered by the caller.
458 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
459 Node* p2, AllocateNode* a2,
460 PhaseTransform* phase) {
461 // Attempt to prove that these two pointers cannot be aliased.
462 // They may both manifestly be allocations, and they should differ.
463 // Or, if they are not both allocations, they can be distinct constants.
464 // Otherwise, one is an allocation and the other a pre-existing value.
465 if (a1 == NULL && a2 == NULL) { // neither an allocation
466 return (p1 != p2) && p1->is_Con() && p2->is_Con();
467 } else if (a1 != NULL && a2 != NULL) { // both allocations
468 return (a1 != a2);
469 } else if (a1 != NULL) { // one allocation a1
470 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.)
471 return all_controls_dominate(p2, a1);
472 } else { //(a2 != NULL) // one allocation a2
473 return all_controls_dominate(p1, a2);
474 }
475 return false;
476 }
477
478
479 // The logic for reordering loads and stores uses four steps:
480 // (a) Walk carefully past stores and initializations which we
481 // can prove are independent of this load.
482 // (b) Observe that the next memory state makes an exact match
483 // with self (load or store), and locate the relevant store.
484 // (c) Ensure that, if we were to wire self directly to the store,
485 // the optimizer would fold it up somehow.
486 // (d) Do the rewiring, and return, depending on some other part of
487 // the optimizer to fold up the load.
488 // This routine handles steps (a) and (b). Steps (c) and (d) are
489 // specific to loads and stores, so they are handled by the callers.
490 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.)
491 //
492 Node* MemNode::find_previous_store(PhaseTransform* phase) {
493 Node* ctrl = in(MemNode::Control);
494 Node* adr = in(MemNode::Address);
495 intptr_t offset = 0;
496 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
497 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase);
498
499 if (offset == Type::OffsetBot)
500 return NULL; // cannot unalias unless there are precise offsets
501
502 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr();
503
504 intptr_t size_in_bytes = memory_size();
505
506 Node* mem = in(MemNode::Memory); // start searching here...
507
508 int cnt = 50; // Cycle limiter
509 for (;;) { // While we can dance past unrelated stores...
510 if (--cnt < 0) break; // Caught in cycle or a complicated dance?
511
512 if (mem->is_Store()) {
513 Node* st_adr = mem->in(MemNode::Address);
514 intptr_t st_offset = 0;
515 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
516 if (st_base == NULL)
517 break; // inscrutable pointer
518 if (st_offset != offset && st_offset != Type::OffsetBot) {
519 const int MAX_STORE = BytesPerLong;
520 if (st_offset >= offset + size_in_bytes ||
521 st_offset <= offset - MAX_STORE ||
522 st_offset <= offset - mem->as_Store()->memory_size()) {
523 // Success: The offsets are provably independent.
524 // (You may ask, why not just test st_offset != offset and be done?
525 // The answer is that stores of different sizes can co-exist
526 // in the same sequence of RawMem effects. We sometimes initialize
527 // a whole 'tile' of array elements with a single jint or jlong.)
528 mem = mem->in(MemNode::Memory);
529 continue; // (a) advance through independent store memory
530 }
531 }
532 if (st_base != base &&
533 detect_ptr_independence(base, alloc,
534 st_base,
535 AllocateNode::Ideal_allocation(st_base, phase),
536 phase)) {
537 // Success: The bases are provably independent.
538 mem = mem->in(MemNode::Memory);
539 continue; // (a) advance through independent store memory
540 }
541
542 // (b) At this point, if the bases or offsets do not agree, we lose,
543 // since we have not managed to prove 'this' and 'mem' independent.
544 if (st_base == base && st_offset == offset) {
545 return mem; // let caller handle steps (c), (d)
546 }
547
548 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
549 InitializeNode* st_init = mem->in(0)->as_Initialize();
550 AllocateNode* st_alloc = st_init->allocation();
551 if (st_alloc == NULL)
552 break; // something degenerated
553 bool known_identical = false;
554 bool known_independent = false;
555 if (alloc == st_alloc)
556 known_identical = true;
557 else if (alloc != NULL)
558 known_independent = true;
559 else if (all_controls_dominate(this, st_alloc))
560 known_independent = true;
561
562 if (known_independent) {
563 // The bases are provably independent: Either they are
564 // manifestly distinct allocations, or else the control
565 // of this load dominates the store's allocation.
566 int alias_idx = phase->C->get_alias_index(adr_type());
567 if (alias_idx == Compile::AliasIdxRaw) {
568 mem = st_alloc->in(TypeFunc::Memory);
569 } else {
570 mem = st_init->memory(alias_idx);
571 }
572 continue; // (a) advance through independent store memory
573 }
574
575 // (b) at this point, if we are not looking at a store initializing
576 // the same allocation we are loading from, we lose.
577 if (known_identical) {
578 // From caller, can_see_stored_value will consult find_captured_store.
579 return mem; // let caller handle steps (c), (d)
580 }
581
582 } else if (addr_t != NULL && addr_t->is_known_instance_field()) {
583 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
584 if (mem->is_Proj() && mem->in(0)->is_Call()) {
585 CallNode *call = mem->in(0)->as_Call();
586 if (!call->may_modify(addr_t, phase)) {
587 mem = call->in(TypeFunc::Memory);
588 continue; // (a) advance through independent call memory
589 }
590 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) {
591 mem = mem->in(0)->in(TypeFunc::Memory);
592 continue; // (a) advance through independent MemBar memory
593 } else if (mem->is_ClearArray()) {
594 if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) {
595 // (the call updated 'mem' value)
596 continue; // (a) advance through independent allocation memory
597 } else {
598 // Can not bypass initialization of the instance
599 // we are looking for.
600 return mem;
601 }
602 } else if (mem->is_MergeMem()) {
603 int alias_idx = phase->C->get_alias_index(adr_type());
604 mem = mem->as_MergeMem()->memory_at(alias_idx);
605 continue; // (a) advance through independent MergeMem memory
606 }
607 }
608
609 // Unless there is an explicit 'continue', we must bail out here,
610 // because 'mem' is an inscrutable memory state (e.g., a call).
611 break;
612 }
613
614 return NULL; // bail out
615 }
616
617 //----------------------calculate_adr_type-------------------------------------
618 // Helper function. Notices when the given type of address hits top or bottom.
619 // Also, asserts a cross-check of the type against the expected address type.
620 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
621 if (t == Type::TOP) return NULL; // does not touch memory any more?
622 #ifdef PRODUCT
623 cross_check = NULL;
624 #else
625 if (!VerifyAliases || is_error_reported() || Node::in_dump()) cross_check = NULL;
626 #endif
627 const TypePtr* tp = t->isa_ptr();
628 if (tp == NULL) {
629 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
630 return TypePtr::BOTTOM; // touches lots of memory
631 } else {
632 #ifdef ASSERT
633 // %%%% [phh] We don't check the alias index if cross_check is
634 // TypeRawPtr::BOTTOM. Needs to be investigated.
635 if (cross_check != NULL &&
636 cross_check != TypePtr::BOTTOM &&
637 cross_check != TypeRawPtr::BOTTOM) {
638 // Recheck the alias index, to see if it has changed (due to a bug).
639 Compile* C = Compile::current();
640 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
641 "must stay in the original alias category");
642 // The type of the address must be contained in the adr_type,
643 // disregarding "null"-ness.
644 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
645 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
646 assert(cross_check->meet(tp_notnull) == cross_check,
647 "real address must not escape from expected memory type");
648 }
649 #endif
650 return tp;
651 }
652 }
653
654 //------------------------adr_phi_is_loop_invariant----------------------------
655 // A helper function for Ideal_DU_postCCP to check if a Phi in a counted
656 // loop is loop invariant. Make a quick traversal of Phi and associated
657 // CastPP nodes, looking to see if they are a closed group within the loop.
658 bool MemNode::adr_phi_is_loop_invariant(Node* adr_phi, Node* cast) {
659 // The idea is that the phi-nest must boil down to only CastPP nodes
660 // with the same data. This implies that any path into the loop already
661 // includes such a CastPP, and so the original cast, whatever its input,
662 // must be covered by an equivalent cast, with an earlier control input.
663 ResourceMark rm;
664
665 // The loop entry input of the phi should be the unique dominating
666 // node for every Phi/CastPP in the loop.
667 Unique_Node_List closure;
668 closure.push(adr_phi->in(LoopNode::EntryControl));
669
670 // Add the phi node and the cast to the worklist.
671 Unique_Node_List worklist;
672 worklist.push(adr_phi);
673 if( cast != NULL ){
674 if( !cast->is_ConstraintCast() ) return false;
675 worklist.push(cast);
676 }
677
678 // Begin recursive walk of phi nodes.
679 while( worklist.size() ){
680 // Take a node off the worklist
681 Node *n = worklist.pop();
682 if( !closure.member(n) ){
683 // Add it to the closure.
684 closure.push(n);
685 // Make a sanity check to ensure we don't waste too much time here.
686 if( closure.size() > 20) return false;
687 // This node is OK if:
688 // - it is a cast of an identical value
689 // - or it is a phi node (then we add its inputs to the worklist)
690 // Otherwise, the node is not OK, and we presume the cast is not invariant
691 if( n->is_ConstraintCast() ){
692 worklist.push(n->in(1));
693 } else if( n->is_Phi() ) {
694 for( uint i = 1; i < n->req(); i++ ) {
695 worklist.push(n->in(i));
696 }
697 } else {
698 return false;
699 }
700 }
701 }
702
703 // Quit when the worklist is empty, and we've found no offending nodes.
704 return true;
705 }
706
707 //------------------------------Ideal_DU_postCCP-------------------------------
708 // Find any cast-away of null-ness and keep its control. Null cast-aways are
709 // going away in this pass and we need to make this memory op depend on the
710 // gating null check.
711 Node *MemNode::Ideal_DU_postCCP( PhaseCCP *ccp ) {
712 return Ideal_common_DU_postCCP(ccp, this, in(MemNode::Address));
713 }
714
715 // I tried to leave the CastPP's in. This makes the graph more accurate in
716 // some sense; we get to keep around the knowledge that an oop is not-null
717 // after some test. Alas, the CastPP's interfere with GVN (some values are
718 // the regular oop, some are the CastPP of the oop, all merge at Phi's which
719 // cannot collapse, etc). This cost us 10% on SpecJVM, even when I removed
720 // some of the more trivial cases in the optimizer. Removing more useless
721 // Phi's started allowing Loads to illegally float above null checks. I gave
722 // up on this approach. CNC 10/20/2000
723 // This static method may be called not from MemNode (EncodePNode calls it).
724 // Only the control edge of the node 'n' might be updated.
725 Node *MemNode::Ideal_common_DU_postCCP( PhaseCCP *ccp, Node* n, Node* adr ) {
726 Node *skipped_cast = NULL;
727 // Need a null check? Regular static accesses do not because they are
728 // from constant addresses. Array ops are gated by the range check (which
729 // always includes a NULL check). Just check field ops.
730 if( n->in(MemNode::Control) == NULL ) {
731 // Scan upwards for the highest location we can place this memory op.
732 while( true ) {
733 switch( adr->Opcode() ) {
734
735 case Op_AddP: // No change to NULL-ness, so peek thru AddP's
736 adr = adr->in(AddPNode::Base);
737 continue;
738
739 case Op_DecodeN: // No change to NULL-ness, so peek thru
740 case Op_DecodeNKlass:
741 adr = adr->in(1);
742 continue;
743
744 case Op_EncodeP:
745 case Op_EncodePKlass:
746 // EncodeP node's control edge could be set by this method
747 // when EncodeP node depends on CastPP node.
748 //
749 // Use its control edge for memory op because EncodeP may go away
750 // later when it is folded with following or preceding DecodeN node.
751 if (adr->in(0) == NULL) {
752 // Keep looking for cast nodes.
753 adr = adr->in(1);
754 continue;
755 }
756 ccp->hash_delete(n);
757 n->set_req(MemNode::Control, adr->in(0));
758 ccp->hash_insert(n);
759 return n;
760
761 case Op_CastPP:
762 // If the CastPP is useless, just peek on through it.
763 if( ccp->type(adr) == ccp->type(adr->in(1)) ) {
764 // Remember the cast that we've peeked though. If we peek
765 // through more than one, then we end up remembering the highest
766 // one, that is, if in a loop, the one closest to the top.
767 skipped_cast = adr;
768 adr = adr->in(1);
769 continue;
770 }
771 // CastPP is going away in this pass! We need this memory op to be
772 // control-dependent on the test that is guarding the CastPP.
773 ccp->hash_delete(n);
774 n->set_req(MemNode::Control, adr->in(0));
775 ccp->hash_insert(n);
776 return n;
777
778 case Op_Phi:
779 // Attempt to float above a Phi to some dominating point.
780 if (adr->in(0) != NULL && adr->in(0)->is_CountedLoop()) {
781 // If we've already peeked through a Cast (which could have set the
782 // control), we can't float above a Phi, because the skipped Cast
783 // may not be loop invariant.
784 if (adr_phi_is_loop_invariant(adr, skipped_cast)) {
785 adr = adr->in(1);
786 continue;
787 }
788 }
789
790 // Intentional fallthrough!
791
792 // No obvious dominating point. The mem op is pinned below the Phi
793 // by the Phi itself. If the Phi goes away (no true value is merged)
794 // then the mem op can float, but not indefinitely. It must be pinned
795 // behind the controls leading to the Phi.
796 case Op_CheckCastPP:
797 // These usually stick around to change address type, however a
798 // useless one can be elided and we still need to pick up a control edge
799 if (adr->in(0) == NULL) {
800 // This CheckCastPP node has NO control and is likely useless. But we
801 // need check further up the ancestor chain for a control input to keep
802 // the node in place. 4959717.
803 skipped_cast = adr;
804 adr = adr->in(1);
805 continue;
806 }
807 ccp->hash_delete(n);
808 n->set_req(MemNode::Control, adr->in(0));
809 ccp->hash_insert(n);
810 return n;
811
812 // List of "safe" opcodes; those that implicitly block the memory
813 // op below any null check.
814 case Op_CastX2P: // no null checks on native pointers
815 case Op_Parm: // 'this' pointer is not null
816 case Op_LoadP: // Loading from within a klass
817 case Op_LoadN: // Loading from within a klass
818 case Op_LoadKlass: // Loading from within a klass
819 case Op_LoadNKlass: // Loading from within a klass
820 case Op_ConP: // Loading from a klass
821 case Op_ConN: // Loading from a klass
822 case Op_ConNKlass: // Loading from a klass
823 case Op_CreateEx: // Sucking up the guts of an exception oop
824 case Op_Con: // Reading from TLS
825 case Op_CMoveP: // CMoveP is pinned
826 case Op_CMoveN: // CMoveN is pinned
827 break; // No progress
828
829 case Op_Proj: // Direct call to an allocation routine
830 case Op_SCMemProj: // Memory state from store conditional ops
831 #ifdef ASSERT
832 {
833 assert(adr->as_Proj()->_con == TypeFunc::Parms, "must be return value");
834 const Node* call = adr->in(0);
835 if (call->is_CallJava()) {
836 const CallJavaNode* call_java = call->as_CallJava();
837 const TypeTuple *r = call_java->tf()->range();
838 assert(r->cnt() > TypeFunc::Parms, "must return value");
839 const Type* ret_type = r->field_at(TypeFunc::Parms);
840 assert(ret_type && ret_type->isa_ptr(), "must return pointer");
841 // We further presume that this is one of
842 // new_instance_Java, new_array_Java, or
843 // the like, but do not assert for this.
844 } else if (call->is_Allocate()) {
845 // similar case to new_instance_Java, etc.
846 } else if (!call->is_CallLeaf()) {
847 // Projections from fetch_oop (OSR) are allowed as well.
848 ShouldNotReachHere();
849 }
850 }
851 #endif
852 break;
853 default:
854 ShouldNotReachHere();
855 }
856 break;
857 }
858 }
859
860 return NULL; // No progress
861 }
862
863
864 //=============================================================================
865 uint LoadNode::size_of() const { return sizeof(*this); }
866 uint LoadNode::cmp( const Node &n ) const
867 { return !Type::cmp( _type, ((LoadNode&)n)._type ); }
868 const Type *LoadNode::bottom_type() const { return _type; }
869 uint LoadNode::ideal_reg() const {
870 return _type->ideal_reg();
871 }
872
873 #ifndef PRODUCT
874 void LoadNode::dump_spec(outputStream *st) const {
875 MemNode::dump_spec(st);
876 if( !Verbose && !WizardMode ) {
877 // standard dump does this in Verbose and WizardMode
878 st->print(" #"); _type->dump_on(st);
879 }
880 }
881 #endif
882
883 #ifdef ASSERT
884 //----------------------------is_immutable_value-------------------------------
885 // Helper function to allow a raw load without control edge for some cases
886 bool LoadNode::is_immutable_value(Node* adr) {
887 return (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() &&
888 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal &&
889 (adr->in(AddPNode::Offset)->find_intptr_t_con(-1) ==
890 in_bytes(JavaThread::osthread_offset())));
891 }
892 #endif
893
894 //----------------------------LoadNode::make-----------------------------------
895 // Polymorphic factory method:
896 Node *LoadNode::make( PhaseGVN& gvn, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt ) {
897 Compile* C = gvn.C;
898
899 // sanity check the alias category against the created node type
900 assert(!(adr_type->isa_oopptr() &&
901 adr_type->offset() == oopDesc::klass_offset_in_bytes()),
902 "use LoadKlassNode instead");
903 assert(!(adr_type->isa_aryptr() &&
904 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
905 "use LoadRangeNode instead");
906 // Check control edge of raw loads
907 assert( ctl != NULL || C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
908 // oop will be recorded in oop map if load crosses safepoint
909 rt->isa_oopptr() || is_immutable_value(adr),
910 "raw memory operations should have control edge");
911 switch (bt) {
912 case T_BOOLEAN: return new (C) LoadUBNode(ctl, mem, adr, adr_type, rt->is_int() );
913 case T_BYTE: return new (C) LoadBNode (ctl, mem, adr, adr_type, rt->is_int() );
914 case T_INT: return new (C) LoadINode (ctl, mem, adr, adr_type, rt->is_int() );
915 case T_CHAR: return new (C) LoadUSNode(ctl, mem, adr, adr_type, rt->is_int() );
916 case T_SHORT: return new (C) LoadSNode (ctl, mem, adr, adr_type, rt->is_int() );
917 case T_LONG: return new (C) LoadLNode (ctl, mem, adr, adr_type, rt->is_long() );
918 case T_FLOAT: return new (C) LoadFNode (ctl, mem, adr, adr_type, rt );
919 case T_DOUBLE: return new (C) LoadDNode (ctl, mem, adr, adr_type, rt );
920 case T_ADDRESS: return new (C) LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr() );
921 case T_OBJECT:
922 #ifdef _LP64
923 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
924 Node* load = gvn.transform(new (C) LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop()));
925 return new (C) DecodeNNode(load, load->bottom_type()->make_ptr());
926 } else
927 #endif
928 {
929 assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop");
930 return new (C) LoadPNode(ctl, mem, adr, adr_type, rt->is_oopptr());
931 }
932 }
933 ShouldNotReachHere();
934 return (LoadNode*)NULL;
935 }
936
937 LoadLNode* LoadLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt) {
938 bool require_atomic = true;
939 return new (C) LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), require_atomic);
940 }
941
942
943
944
945 //------------------------------hash-------------------------------------------
946 uint LoadNode::hash() const {
947 // unroll addition of interesting fields
948 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
949 }
950
951 //---------------------------can_see_stored_value------------------------------
952 // This routine exists to make sure this set of tests is done the same
953 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
954 // will change the graph shape in a way which makes memory alive twice at the
955 // same time (uses the Oracle model of aliasing), then some
956 // LoadXNode::Identity will fold things back to the equivalence-class model
957 // of aliasing.
958 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const {
959 Node* ld_adr = in(MemNode::Address);
960
961 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
962 Compile::AliasType* atp = tp != NULL ? phase->C->alias_type(tp) : NULL;
963 if (EliminateAutoBox && atp != NULL && atp->index() >= Compile::AliasIdxRaw &&
964 atp->field() != NULL && !atp->field()->is_volatile()) {
965 uint alias_idx = atp->index();
966 bool final = atp->field()->is_final();
967 Node* result = NULL;
968 Node* current = st;
969 // Skip through chains of MemBarNodes checking the MergeMems for
970 // new states for the slice of this load. Stop once any other
971 // kind of node is encountered. Loads from final memory can skip
972 // through any kind of MemBar but normal loads shouldn't skip
973 // through MemBarAcquire since the could allow them to move out of
974 // a synchronized region.
975 while (current->is_Proj()) {
976 int opc = current->in(0)->Opcode();
977 if ((final && (opc == Op_MemBarAcquire || opc == Op_MemBarAcquireLock)) ||
978 opc == Op_MemBarRelease || opc == Op_MemBarCPUOrder ||
979 opc == Op_MemBarReleaseLock) {
980 Node* mem = current->in(0)->in(TypeFunc::Memory);
981 if (mem->is_MergeMem()) {
982 MergeMemNode* merge = mem->as_MergeMem();
983 Node* new_st = merge->memory_at(alias_idx);
984 if (new_st == merge->base_memory()) {
985 // Keep searching
986 current = merge->base_memory();
987 continue;
988 }
989 // Save the new memory state for the slice and fall through
990 // to exit.
991 result = new_st;
992 }
993 }
994 break;
995 }
996 if (result != NULL) {
997 st = result;
998 }
999 }
1000
1001
1002 // Loop around twice in the case Load -> Initialize -> Store.
1003 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
1004 for (int trip = 0; trip <= 1; trip++) {
1005
1006 if (st->is_Store()) {
1007 Node* st_adr = st->in(MemNode::Address);
1008 if (!phase->eqv(st_adr, ld_adr)) {
1009 // Try harder before giving up... Match raw and non-raw pointers.
1010 intptr_t st_off = 0;
1011 AllocateNode* alloc = AllocateNode::Ideal_allocation(st_adr, phase, st_off);
1012 if (alloc == NULL) return NULL;
1013 intptr_t ld_off = 0;
1014 AllocateNode* allo2 = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
1015 if (alloc != allo2) return NULL;
1016 if (ld_off != st_off) return NULL;
1017 // At this point we have proven something like this setup:
1018 // A = Allocate(...)
1019 // L = LoadQ(, AddP(CastPP(, A.Parm),, #Off))
1020 // S = StoreQ(, AddP(, A.Parm , #Off), V)
1021 // (Actually, we haven't yet proven the Q's are the same.)
1022 // In other words, we are loading from a casted version of
1023 // the same pointer-and-offset that we stored to.
1024 // Thus, we are able to replace L by V.
1025 }
1026 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
1027 if (store_Opcode() != st->Opcode())
1028 return NULL;
1029 return st->in(MemNode::ValueIn);
1030 }
1031
1032 intptr_t offset = 0; // scratch
1033
1034 // A load from a freshly-created object always returns zero.
1035 // (This can happen after LoadNode::Ideal resets the load's memory input
1036 // to find_captured_store, which returned InitializeNode::zero_memory.)
1037 if (st->is_Proj() && st->in(0)->is_Allocate() &&
1038 st->in(0) == AllocateNode::Ideal_allocation(ld_adr, phase, offset) &&
1039 offset >= st->in(0)->as_Allocate()->minimum_header_size()) {
1040 // return a zero value for the load's basic type
1041 // (This is one of the few places where a generic PhaseTransform
1042 // can create new nodes. Think of it as lazily manifesting
1043 // virtually pre-existing constants.)
1044 return phase->zerocon(memory_type());
1045 }
1046
1047 // A load from an initialization barrier can match a captured store.
1048 if (st->is_Proj() && st->in(0)->is_Initialize()) {
1049 InitializeNode* init = st->in(0)->as_Initialize();
1050 AllocateNode* alloc = init->allocation();
1051 if (alloc != NULL &&
1052 alloc == AllocateNode::Ideal_allocation(ld_adr, phase, offset)) {
1053 // examine a captured store value
1054 st = init->find_captured_store(offset, memory_size(), phase);
1055 if (st != NULL)
1056 continue; // take one more trip around
1057 }
1058 }
1059
1060 break;
1061 }
1062
1063 return NULL;
1064 }
1065
1066 //----------------------is_instance_field_load_with_local_phi------------------
1067 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
1068 if( in(MemNode::Memory)->is_Phi() && in(MemNode::Memory)->in(0) == ctrl &&
1069 in(MemNode::Address)->is_AddP() ) {
1070 const TypeOopPtr* t_oop = in(MemNode::Address)->bottom_type()->isa_oopptr();
1071 // Only instances.
1072 if( t_oop != NULL && t_oop->is_known_instance_field() &&
1073 t_oop->offset() != Type::OffsetBot &&
1074 t_oop->offset() != Type::OffsetTop) {
1075 return true;
1076 }
1077 }
1078 return false;
1079 }
1080
1081 //------------------------------Identity---------------------------------------
1082 // Loads are identity if previous store is to same address
1083 Node *LoadNode::Identity( PhaseTransform *phase ) {
1084 // If the previous store-maker is the right kind of Store, and the store is
1085 // to the same address, then we are equal to the value stored.
1086 Node* mem = in(MemNode::Memory);
1087 Node* value = can_see_stored_value(mem, phase);
1088 if( value ) {
1089 // byte, short & char stores truncate naturally.
1090 // A load has to load the truncated value which requires
1091 // some sort of masking operation and that requires an
1092 // Ideal call instead of an Identity call.
1093 if (memory_size() < BytesPerInt) {
1094 // If the input to the store does not fit with the load's result type,
1095 // it must be truncated via an Ideal call.
1096 if (!phase->type(value)->higher_equal(phase->type(this)))
1097 return this;
1098 }
1099 // (This works even when value is a Con, but LoadNode::Value
1100 // usually runs first, producing the singleton type of the Con.)
1101 return value;
1102 }
1103
1104 // Search for an existing data phi which was generated before for the same
1105 // instance's field to avoid infinite generation of phis in a loop.
1106 Node *region = mem->in(0);
1107 if (is_instance_field_load_with_local_phi(region)) {
1108 const TypePtr *addr_t = in(MemNode::Address)->bottom_type()->isa_ptr();
1109 int this_index = phase->C->get_alias_index(addr_t);
1110 int this_offset = addr_t->offset();
1111 int this_id = addr_t->is_oopptr()->instance_id();
1112 const Type* this_type = bottom_type();
1113 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1114 Node* phi = region->fast_out(i);
1115 if (phi->is_Phi() && phi != mem &&
1116 phi->as_Phi()->is_same_inst_field(this_type, this_id, this_index, this_offset)) {
1117 return phi;
1118 }
1119 }
1120 }
1121
1122 return this;
1123 }
1124
1125
1126 // Returns true if the AliasType refers to the field that holds the
1127 // cached box array. Currently only handles the IntegerCache case.
1128 static bool is_autobox_cache(Compile::AliasType* atp) {
1129 if (atp != NULL && atp->field() != NULL) {
1130 ciField* field = atp->field();
1131 ciSymbol* klass = field->holder()->name();
1132 if (field->name() == ciSymbol::cache_field_name() &&
1133 field->holder()->uses_default_loader() &&
1134 klass == ciSymbol::java_lang_Integer_IntegerCache()) {
1135 return true;
1136 }
1137 }
1138 return false;
1139 }
1140
1141 // Fetch the base value in the autobox array
1142 static bool fetch_autobox_base(Compile::AliasType* atp, int& cache_offset) {
1143 if (atp != NULL && atp->field() != NULL) {
1144 ciField* field = atp->field();
1145 ciSymbol* klass = field->holder()->name();
1146 if (field->name() == ciSymbol::cache_field_name() &&
1147 field->holder()->uses_default_loader() &&
1148 klass == ciSymbol::java_lang_Integer_IntegerCache()) {
1149 assert(field->is_constant(), "what?");
1150 ciObjArray* array = field->constant_value().as_object()->as_obj_array();
1151 // Fetch the box object at the base of the array and get its value
1152 ciInstance* box = array->obj_at(0)->as_instance();
1153 ciInstanceKlass* ik = box->klass()->as_instance_klass();
1154 if (ik->nof_nonstatic_fields() == 1) {
1155 // This should be true nonstatic_field_at requires calling
1156 // nof_nonstatic_fields so check it anyway
1157 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1158 cache_offset = c.as_int();
1159 }
1160 return true;
1161 }
1162 }
1163 return false;
1164 }
1165
1166 // Returns true if the AliasType refers to the value field of an
1167 // autobox object. Currently only handles Integer.
1168 static bool is_autobox_object(Compile::AliasType* atp) {
1169 if (atp != NULL && atp->field() != NULL) {
1170 ciField* field = atp->field();
1171 ciSymbol* klass = field->holder()->name();
1172 if (field->name() == ciSymbol::value_name() &&
1173 field->holder()->uses_default_loader() &&
1174 klass == ciSymbol::java_lang_Integer()) {
1175 return true;
1176 }
1177 }
1178 return false;
1179 }
1180
1181
1182 // We're loading from an object which has autobox behaviour.
1183 // If this object is result of a valueOf call we'll have a phi
1184 // merging a newly allocated object and a load from the cache.
1185 // We want to replace this load with the original incoming
1186 // argument to the valueOf call.
1187 Node* LoadNode::eliminate_autobox(PhaseGVN* phase) {
1188 Node* base = in(Address)->in(AddPNode::Base);
1189 if (base->is_Phi() && base->req() == 3) {
1190 AllocateNode* allocation = NULL;
1191 int allocation_index = -1;
1192 int load_index = -1;
1193 for (uint i = 1; i < base->req(); i++) {
1194 allocation = AllocateNode::Ideal_allocation(base->in(i), phase);
1195 if (allocation != NULL) {
1196 allocation_index = i;
1197 load_index = 3 - allocation_index;
1198 break;
1199 }
1200 }
1201 bool has_load = ( allocation != NULL &&
1202 (base->in(load_index)->is_Load() ||
1203 base->in(load_index)->is_DecodeN() &&
1204 base->in(load_index)->in(1)->is_Load()) );
1205 if (has_load && in(Memory)->is_Phi() && in(Memory)->in(0) == base->in(0)) {
1206 // Push the loads from the phi that comes from valueOf up
1207 // through it to allow elimination of the loads and the recovery
1208 // of the original value.
1209 Node* mem_phi = in(Memory);
1210 Node* offset = in(Address)->in(AddPNode::Offset);
1211 Node* region = base->in(0);
1212
1213 Node* in1 = clone();
1214 Node* in1_addr = in1->in(Address)->clone();
1215 in1_addr->set_req(AddPNode::Base, base->in(allocation_index));
1216 in1_addr->set_req(AddPNode::Address, base->in(allocation_index));
1217 in1_addr->set_req(AddPNode::Offset, offset);
1218 in1->set_req(0, region->in(allocation_index));
1219 in1->set_req(Address, in1_addr);
1220 in1->set_req(Memory, mem_phi->in(allocation_index));
1221
1222 Node* in2 = clone();
1223 Node* in2_addr = in2->in(Address)->clone();
1224 in2_addr->set_req(AddPNode::Base, base->in(load_index));
1225 in2_addr->set_req(AddPNode::Address, base->in(load_index));
1226 in2_addr->set_req(AddPNode::Offset, offset);
1227 in2->set_req(0, region->in(load_index));
1228 in2->set_req(Address, in2_addr);
1229 in2->set_req(Memory, mem_phi->in(load_index));
1230
1231 in1_addr = phase->transform(in1_addr);
1232 in1 = phase->transform(in1);
1233 in2_addr = phase->transform(in2_addr);
1234 in2 = phase->transform(in2);
1235
1236 PhiNode* result = PhiNode::make_blank(region, this);
1237 result->set_req(allocation_index, in1);
1238 result->set_req(load_index, in2);
1239 return result;
1240 }
1241 } else if (base->is_Load() ||
1242 base->is_DecodeN() && base->in(1)->is_Load()) {
1243 if (base->is_DecodeN()) {
1244 // Get LoadN node which loads cached Integer object
1245 base = base->in(1);
1246 }
1247 // Eliminate the load of Integer.value for integers from the cache
1248 // array by deriving the value from the index into the array.
1249 // Capture the offset of the load and then reverse the computation.
1250 Node* load_base = base->in(Address)->in(AddPNode::Base);
1251 if (load_base->is_DecodeN()) {
1252 // Get LoadN node which loads IntegerCache.cache field
1253 load_base = load_base->in(1);
1254 }
1255 if (load_base != NULL) {
1256 Compile::AliasType* atp = phase->C->alias_type(load_base->adr_type());
1257 intptr_t cache_offset;
1258 int shift = -1;
1259 Node* cache = NULL;
1260 if (is_autobox_cache(atp)) {
1261 shift = exact_log2(type2aelembytes(T_OBJECT));
1262 cache = AddPNode::Ideal_base_and_offset(load_base->in(Address), phase, cache_offset);
1263 }
1264 if (cache != NULL && base->in(Address)->is_AddP()) {
1265 Node* elements[4];
1266 int count = base->in(Address)->as_AddP()->unpack_offsets(elements, ARRAY_SIZE(elements));
1267 int cache_low;
1268 if (count > 0 && fetch_autobox_base(atp, cache_low)) {
1269 int offset = arrayOopDesc::base_offset_in_bytes(memory_type()) - (cache_low << shift);
1270 // Add up all the offsets making of the address of the load
1271 Node* result = elements[0];
1272 for (int i = 1; i < count; i++) {
1273 result = phase->transform(new (phase->C) AddXNode(result, elements[i]));
1274 }
1275 // Remove the constant offset from the address and then
1276 // remove the scaling of the offset to recover the original index.
1277 result = phase->transform(new (phase->C) AddXNode(result, phase->MakeConX(-offset)));
1278 if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) {
1279 // Peel the shift off directly but wrap it in a dummy node
1280 // since Ideal can't return existing nodes
1281 result = new (phase->C) RShiftXNode(result->in(1), phase->intcon(0));
1282 } else {
1283 result = new (phase->C) RShiftXNode(result, phase->intcon(shift));
1284 }
1285 #ifdef _LP64
1286 result = new (phase->C) ConvL2INode(phase->transform(result));
1287 #endif
1288 return result;
1289 }
1290 }
1291 }
1292 }
1293 return NULL;
1294 }
1295
1296 //------------------------------split_through_phi------------------------------
1297 // Split instance field load through Phi.
1298 Node *LoadNode::split_through_phi(PhaseGVN *phase) {
1299 Node* mem = in(MemNode::Memory);
1300 Node* address = in(MemNode::Address);
1301 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1302 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1303
1304 assert(mem->is_Phi() && (t_oop != NULL) &&
1305 t_oop->is_known_instance_field(), "invalide conditions");
1306
1307 Node *region = mem->in(0);
1308 if (region == NULL) {
1309 return NULL; // Wait stable graph
1310 }
1311 uint cnt = mem->req();
1312 for (uint i = 1; i < cnt; i++) {
1313 Node* rc = region->in(i);
1314 if (rc == NULL || phase->type(rc) == Type::TOP)
1315 return NULL; // Wait stable graph
1316 Node *in = mem->in(i);
1317 if (in == NULL) {
1318 return NULL; // Wait stable graph
1319 }
1320 }
1321 // Check for loop invariant.
1322 if (cnt == 3) {
1323 for (uint i = 1; i < cnt; i++) {
1324 Node *in = mem->in(i);
1325 Node* m = MemNode::optimize_memory_chain(in, addr_t, phase);
1326 if (m == mem) {
1327 set_req(MemNode::Memory, mem->in(cnt - i)); // Skip this phi.
1328 return this;
1329 }
1330 }
1331 }
1332 // Split through Phi (see original code in loopopts.cpp).
1333 assert(phase->C->have_alias_type(addr_t), "instance should have alias type");
1334
1335 // Do nothing here if Identity will find a value
1336 // (to avoid infinite chain of value phis generation).
1337 if (!phase->eqv(this, this->Identity(phase)))
1338 return NULL;
1339
1340 // Skip the split if the region dominates some control edge of the address.
1341 if (!MemNode::all_controls_dominate(address, region))
1342 return NULL;
1343
1344 const Type* this_type = this->bottom_type();
1345 int this_index = phase->C->get_alias_index(addr_t);
1346 int this_offset = addr_t->offset();
1347 int this_iid = addr_t->is_oopptr()->instance_id();
1348 PhaseIterGVN *igvn = phase->is_IterGVN();
1349 Node *phi = new (igvn->C) PhiNode(region, this_type, NULL, this_iid, this_index, this_offset);
1350 for (uint i = 1; i < region->req(); i++) {
1351 Node *x;
1352 Node* the_clone = NULL;
1353 if (region->in(i) == phase->C->top()) {
1354 x = phase->C->top(); // Dead path? Use a dead data op
1355 } else {
1356 x = this->clone(); // Else clone up the data op
1357 the_clone = x; // Remember for possible deletion.
1358 // Alter data node to use pre-phi inputs
1359 if (this->in(0) == region) {
1360 x->set_req(0, region->in(i));
1361 } else {
1362 x->set_req(0, NULL);
1363 }
1364 for (uint j = 1; j < this->req(); j++) {
1365 Node *in = this->in(j);
1366 if (in->is_Phi() && in->in(0) == region)
1367 x->set_req(j, in->in(i)); // Use pre-Phi input for the clone
1368 }
1369 }
1370 // Check for a 'win' on some paths
1371 const Type *t = x->Value(igvn);
1372
1373 bool singleton = t->singleton();
1374
1375 // See comments in PhaseIdealLoop::split_thru_phi().
1376 if (singleton && t == Type::TOP) {
1377 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1378 }
1379
1380 if (singleton) {
1381 x = igvn->makecon(t);
1382 } else {
1383 // We now call Identity to try to simplify the cloned node.
1384 // Note that some Identity methods call phase->type(this).
1385 // Make sure that the type array is big enough for
1386 // our new node, even though we may throw the node away.
1387 // (This tweaking with igvn only works because x is a new node.)
1388 igvn->set_type(x, t);
1389 // If x is a TypeNode, capture any more-precise type permanently into Node
1390 // otherwise it will be not updated during igvn->transform since
1391 // igvn->type(x) is set to x->Value() already.
1392 x->raise_bottom_type(t);
1393 Node *y = x->Identity(igvn);
1394 if (y != x) {
1395 x = y;
1396 } else {
1397 y = igvn->hash_find(x);
1398 if (y) {
1399 x = y;
1400 } else {
1401 // Else x is a new node we are keeping
1402 // We do not need register_new_node_with_optimizer
1403 // because set_type has already been called.
1404 igvn->_worklist.push(x);
1405 }
1406 }
1407 }
1408 if (x != the_clone && the_clone != NULL)
1409 igvn->remove_dead_node(the_clone);
1410 phi->set_req(i, x);
1411 }
1412 // Record Phi
1413 igvn->register_new_node_with_optimizer(phi);
1414 return phi;
1415 }
1416
1417 //------------------------------Ideal------------------------------------------
1418 // If the load is from Field memory and the pointer is non-null, we can
1419 // zero out the control input.
1420 // If the offset is constant and the base is an object allocation,
1421 // try to hook me up to the exact initializing store.
1422 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1423 Node* p = MemNode::Ideal_common(phase, can_reshape);
1424 if (p) return (p == NodeSentinel) ? NULL : p;
1425
1426 Node* ctrl = in(MemNode::Control);
1427 Node* address = in(MemNode::Address);
1428
1429 // Skip up past a SafePoint control. Cannot do this for Stores because
1430 // pointer stores & cardmarks must stay on the same side of a SafePoint.
1431 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint &&
1432 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw ) {
1433 ctrl = ctrl->in(0);
1434 set_req(MemNode::Control,ctrl);
1435 }
1436
1437 intptr_t ignore = 0;
1438 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1439 if (base != NULL
1440 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
1441 // Check for useless control edge in some common special cases
1442 if (in(MemNode::Control) != NULL
1443 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1444 && all_controls_dominate(base, phase->C->start())) {
1445 // A method-invariant, non-null address (constant or 'this' argument).
1446 set_req(MemNode::Control, NULL);
1447 }
1448
1449 if (EliminateAutoBox && can_reshape) {
1450 assert(!phase->type(base)->higher_equal(TypePtr::NULL_PTR), "the autobox pointer should be non-null");
1451 Compile::AliasType* atp = phase->C->alias_type(adr_type());
1452 if (is_autobox_object(atp)) {
1453 Node* result = eliminate_autobox(phase);
1454 if (result != NULL) return result;
1455 }
1456 }
1457 }
1458
1459 Node* mem = in(MemNode::Memory);
1460 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1461
1462 if (addr_t != NULL) {
1463 // try to optimize our memory input
1464 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, phase);
1465 if (opt_mem != mem) {
1466 set_req(MemNode::Memory, opt_mem);
1467 if (phase->type( opt_mem ) == Type::TOP) return NULL;
1468 return this;
1469 }
1470 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1471 if (can_reshape && opt_mem->is_Phi() &&
1472 (t_oop != NULL) && t_oop->is_known_instance_field()) {
1473 PhaseIterGVN *igvn = phase->is_IterGVN();
1474 if (igvn != NULL && igvn->_worklist.member(opt_mem)) {
1475 // Delay this transformation until memory Phi is processed.
1476 phase->is_IterGVN()->_worklist.push(this);
1477 return NULL;
1478 }
1479 // Split instance field load through Phi.
1480 Node* result = split_through_phi(phase);
1481 if (result != NULL) return result;
1482 }
1483 }
1484
1485 // Check for prior store with a different base or offset; make Load
1486 // independent. Skip through any number of them. Bail out if the stores
1487 // are in an endless dead cycle and report no progress. This is a key
1488 // transform for Reflection. However, if after skipping through the Stores
1489 // we can't then fold up against a prior store do NOT do the transform as
1490 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
1491 // array memory alive twice: once for the hoisted Load and again after the
1492 // bypassed Store. This situation only works if EVERYBODY who does
1493 // anti-dependence work knows how to bypass. I.e. we need all
1494 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
1495 // the alias index stuff. So instead, peek through Stores and IFF we can
1496 // fold up, do so.
1497 Node* prev_mem = find_previous_store(phase);
1498 // Steps (a), (b): Walk past independent stores to find an exact match.
1499 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) {
1500 // (c) See if we can fold up on the spot, but don't fold up here.
1501 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
1502 // just return a prior value, which is done by Identity calls.
1503 if (can_see_stored_value(prev_mem, phase)) {
1504 // Make ready for step (d):
1505 set_req(MemNode::Memory, prev_mem);
1506 return this;
1507 }
1508 }
1509
1510 return NULL; // No further progress
1511 }
1512
1513 // Helper to recognize certain Klass fields which are invariant across
1514 // some group of array types (e.g., int[] or all T[] where T < Object).
1515 const Type*
1516 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1517 ciKlass* klass) const {
1518 if (tkls->offset() == in_bytes(Klass::modifier_flags_offset())) {
1519 // The field is Klass::_modifier_flags. Return its (constant) value.
1520 // (Folds up the 2nd indirection in aClassConstant.getModifiers().)
1521 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags");
1522 return TypeInt::make(klass->modifier_flags());
1523 }
1524 if (tkls->offset() == in_bytes(Klass::access_flags_offset())) {
1525 // The field is Klass::_access_flags. Return its (constant) value.
1526 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1527 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags");
1528 return TypeInt::make(klass->access_flags());
1529 }
1530 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) {
1531 // The field is Klass::_layout_helper. Return its constant value if known.
1532 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper");
1533 return TypeInt::make(klass->layout_helper());
1534 }
1535
1536 // No match.
1537 return NULL;
1538 }
1539
1540 //------------------------------Value-----------------------------------------
1541 const Type *LoadNode::Value( PhaseTransform *phase ) const {
1542 // Either input is TOP ==> the result is TOP
1543 Node* mem = in(MemNode::Memory);
1544 const Type *t1 = phase->type(mem);
1545 if (t1 == Type::TOP) return Type::TOP;
1546 Node* adr = in(MemNode::Address);
1547 const TypePtr* tp = phase->type(adr)->isa_ptr();
1548 if (tp == NULL || tp->empty()) return Type::TOP;
1549 int off = tp->offset();
1550 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
1551 Compile* C = phase->C;
1552
1553 // Try to guess loaded type from pointer type
1554 if (tp->base() == Type::AryPtr) {
1555 const Type *t = tp->is_aryptr()->elem();
1556 // Don't do this for integer types. There is only potential profit if
1557 // the element type t is lower than _type; that is, for int types, if _type is
1558 // more restrictive than t. This only happens here if one is short and the other
1559 // char (both 16 bits), and in those cases we've made an intentional decision
1560 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
1561 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
1562 //
1563 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
1564 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
1565 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
1566 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
1567 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
1568 // In fact, that could have been the original type of p1, and p1 could have
1569 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
1570 // expression (LShiftL quux 3) independently optimized to the constant 8.
1571 if ((t->isa_int() == NULL) && (t->isa_long() == NULL)
1572 && (_type->isa_vect() == NULL)
1573 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
1574 // t might actually be lower than _type, if _type is a unique
1575 // concrete subclass of abstract class t.
1576 // Make sure the reference is not into the header, by comparing
1577 // the offset against the offset of the start of the array's data.
1578 // Different array types begin at slightly different offsets (12 vs. 16).
1579 // We choose T_BYTE as an example base type that is least restrictive
1580 // as to alignment, which will therefore produce the smallest
1581 // possible base offset.
1582 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
1583 if ((uint)off >= (uint)min_base_off) { // is the offset beyond the header?
1584 const Type* jt = t->join(_type);
1585 // In any case, do not allow the join, per se, to empty out the type.
1586 if (jt->empty() && !t->empty()) {
1587 // This can happen if a interface-typed array narrows to a class type.
1588 jt = _type;
1589 }
1590
1591 if (EliminateAutoBox && adr->is_AddP()) {
1592 // The pointers in the autobox arrays are always non-null
1593 Node* base = adr->in(AddPNode::Base);
1594 if (base != NULL &&
1595 !phase->type(base)->higher_equal(TypePtr::NULL_PTR)) {
1596 Compile::AliasType* atp = C->alias_type(base->adr_type());
1597 if (is_autobox_cache(atp)) {
1598 return jt->join(TypePtr::NOTNULL)->is_ptr();
1599 }
1600 }
1601 }
1602 return jt;
1603 }
1604 }
1605 } else if (tp->base() == Type::InstPtr) {
1606 ciEnv* env = C->env();
1607 const TypeInstPtr* tinst = tp->is_instptr();
1608 ciKlass* klass = tinst->klass();
1609 assert( off != Type::OffsetBot ||
1610 // arrays can be cast to Objects
1611 tp->is_oopptr()->klass()->is_java_lang_Object() ||
1612 // unsafe field access may not have a constant offset
1613 C->has_unsafe_access(),
1614 "Field accesses must be precise" );
1615 // For oop loads, we expect the _type to be precise
1616 if (klass == env->String_klass() &&
1617 adr->is_AddP() && off != Type::OffsetBot) {
1618 // For constant Strings treat the final fields as compile time constants.
1619 Node* base = adr->in(AddPNode::Base);
1620 const TypeOopPtr* t = phase->type(base)->isa_oopptr();
1621 if (t != NULL && t->singleton()) {
1622 ciField* field = env->String_klass()->get_field_by_offset(off, false);
1623 if (field != NULL && field->is_final()) {
1624 ciObject* string = t->const_oop();
1625 ciConstant constant = string->as_instance()->field_value(field);
1626 if (constant.basic_type() == T_INT) {
1627 return TypeInt::make(constant.as_int());
1628 } else if (constant.basic_type() == T_ARRAY) {
1629 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
1630 return TypeNarrowOop::make_from_constant(constant.as_object(), true);
1631 } else {
1632 return TypeOopPtr::make_from_constant(constant.as_object(), true);
1633 }
1634 }
1635 }
1636 }
1637 }
1638 // Optimizations for constant objects
1639 ciObject* const_oop = tinst->const_oop();
1640 if (const_oop != NULL) {
1641 // For constant CallSites treat the target field as a compile time constant.
1642 if (const_oop->is_call_site()) {
1643 ciCallSite* call_site = const_oop->as_call_site();
1644 ciField* field = call_site->klass()->as_instance_klass()->get_field_by_offset(off, /*is_static=*/ false);
1645 if (field != NULL && field->is_call_site_target()) {
1646 ciMethodHandle* target = call_site->get_target();
1647 if (target != NULL) { // just in case
1648 ciConstant constant(T_OBJECT, target);
1649 const Type* t;
1650 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
1651 t = TypeNarrowOop::make_from_constant(constant.as_object(), true);
1652 } else {
1653 t = TypeOopPtr::make_from_constant(constant.as_object(), true);
1654 }
1655 // Add a dependence for invalidation of the optimization.
1656 if (!call_site->is_constant_call_site()) {
1657 C->dependencies()->assert_call_site_target_value(call_site, target);
1658 }
1659 return t;
1660 }
1661 }
1662 }
1663 }
1664 } else if (tp->base() == Type::KlassPtr) {
1665 assert( off != Type::OffsetBot ||
1666 // arrays can be cast to Objects
1667 tp->is_klassptr()->klass()->is_java_lang_Object() ||
1668 // also allow array-loading from the primary supertype
1669 // array during subtype checks
1670 Opcode() == Op_LoadKlass,
1671 "Field accesses must be precise" );
1672 // For klass/static loads, we expect the _type to be precise
1673 }
1674
1675 const TypeKlassPtr *tkls = tp->isa_klassptr();
1676 if (tkls != NULL && !StressReflectiveCode) {
1677 ciKlass* klass = tkls->klass();
1678 if (klass->is_loaded() && tkls->klass_is_exact()) {
1679 // We are loading a field from a Klass metaobject whose identity
1680 // is known at compile time (the type is "exact" or "precise").
1681 // Check for fields we know are maintained as constants by the VM.
1682 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) {
1683 // The field is Klass::_super_check_offset. Return its (constant) value.
1684 // (Folds up type checking code.)
1685 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
1686 return TypeInt::make(klass->super_check_offset());
1687 }
1688 // Compute index into primary_supers array
1689 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1690 // Check for overflowing; use unsigned compare to handle the negative case.
1691 if( depth < ciKlass::primary_super_limit() ) {
1692 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1693 // (Folds up type checking code.)
1694 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1695 ciKlass *ss = klass->super_of_depth(depth);
1696 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1697 }
1698 const Type* aift = load_array_final_field(tkls, klass);
1699 if (aift != NULL) return aift;
1700 if (tkls->offset() == in_bytes(ArrayKlass::component_mirror_offset())
1701 && klass->is_array_klass()) {
1702 // The field is ArrayKlass::_component_mirror. Return its (constant) value.
1703 // (Folds up aClassConstant.getComponentType, common in Arrays.copyOf.)
1704 assert(Opcode() == Op_LoadP, "must load an oop from _component_mirror");
1705 return TypeInstPtr::make(klass->as_array_klass()->component_mirror());
1706 }
1707 if (tkls->offset() == in_bytes(Klass::java_mirror_offset())) {
1708 // The field is Klass::_java_mirror. Return its (constant) value.
1709 // (Folds up the 2nd indirection in anObjConstant.getClass().)
1710 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
1711 return TypeInstPtr::make(klass->java_mirror());
1712 }
1713 }
1714
1715 // We can still check if we are loading from the primary_supers array at a
1716 // shallow enough depth. Even though the klass is not exact, entries less
1717 // than or equal to its super depth are correct.
1718 if (klass->is_loaded() ) {
1719 ciType *inner = klass;
1720 while( inner->is_obj_array_klass() )
1721 inner = inner->as_obj_array_klass()->base_element_type();
1722 if( inner->is_instance_klass() &&
1723 !inner->as_instance_klass()->flags().is_interface() ) {
1724 // Compute index into primary_supers array
1725 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1726 // Check for overflowing; use unsigned compare to handle the negative case.
1727 if( depth < ciKlass::primary_super_limit() &&
1728 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case
1729 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1730 // (Folds up type checking code.)
1731 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1732 ciKlass *ss = klass->super_of_depth(depth);
1733 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1734 }
1735 }
1736 }
1737
1738 // If the type is enough to determine that the thing is not an array,
1739 // we can give the layout_helper a positive interval type.
1740 // This will help short-circuit some reflective code.
1741 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())
1742 && !klass->is_array_klass() // not directly typed as an array
1743 && !klass->is_interface() // specifically not Serializable & Cloneable
1744 && !klass->is_java_lang_Object() // not the supertype of all T[]
1745 ) {
1746 // Note: When interfaces are reliable, we can narrow the interface
1747 // test to (klass != Serializable && klass != Cloneable).
1748 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
1749 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
1750 // The key property of this type is that it folds up tests
1751 // for array-ness, since it proves that the layout_helper is positive.
1752 // Thus, a generic value like the basic object layout helper works fine.
1753 return TypeInt::make(min_size, max_jint, Type::WidenMin);
1754 }
1755 }
1756
1757 // If we are loading from a freshly-allocated object, produce a zero,
1758 // if the load is provably beyond the header of the object.
1759 // (Also allow a variable load from a fresh array to produce zero.)
1760 const TypeOopPtr *tinst = tp->isa_oopptr();
1761 bool is_instance = (tinst != NULL) && tinst->is_known_instance_field();
1762 if (ReduceFieldZeroing || is_instance) {
1763 Node* value = can_see_stored_value(mem,phase);
1764 if (value != NULL && value->is_Con()) {
1765 assert(value->bottom_type()->higher_equal(_type),"sanity");
1766 return value->bottom_type();
1767 }
1768 }
1769
1770 if (is_instance) {
1771 // If we have an instance type and our memory input is the
1772 // programs's initial memory state, there is no matching store,
1773 // so just return a zero of the appropriate type
1774 Node *mem = in(MemNode::Memory);
1775 if (mem->is_Parm() && mem->in(0)->is_Start()) {
1776 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
1777 return Type::get_zero_type(_type->basic_type());
1778 }
1779 }
1780 return _type;
1781 }
1782
1783 //------------------------------match_edge-------------------------------------
1784 // Do we Match on this edge index or not? Match only the address.
1785 uint LoadNode::match_edge(uint idx) const {
1786 return idx == MemNode::Address;
1787 }
1788
1789 //--------------------------LoadBNode::Ideal--------------------------------------
1790 //
1791 // If the previous store is to the same address as this load,
1792 // and the value stored was larger than a byte, replace this load
1793 // with the value stored truncated to a byte. If no truncation is
1794 // needed, the replacement is done in LoadNode::Identity().
1795 //
1796 Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1797 Node* mem = in(MemNode::Memory);
1798 Node* value = can_see_stored_value(mem,phase);
1799 if( value && !phase->type(value)->higher_equal( _type ) ) {
1800 Node *result = phase->transform( new (phase->C) LShiftINode(value, phase->intcon(24)) );
1801 return new (phase->C) RShiftINode(result, phase->intcon(24));
1802 }
1803 // Identity call will handle the case where truncation is not needed.
1804 return LoadNode::Ideal(phase, can_reshape);
1805 }
1806
1807 const Type* LoadBNode::Value(PhaseTransform *phase) const {
1808 Node* mem = in(MemNode::Memory);
1809 Node* value = can_see_stored_value(mem,phase);
1810 if (value != NULL && value->is_Con() &&
1811 !value->bottom_type()->higher_equal(_type)) {
1812 // If the input to the store does not fit with the load's result type,
1813 // it must be truncated. We can't delay until Ideal call since
1814 // a singleton Value is needed for split_thru_phi optimization.
1815 int con = value->get_int();
1816 return TypeInt::make((con << 24) >> 24);
1817 }
1818 return LoadNode::Value(phase);
1819 }
1820
1821 //--------------------------LoadUBNode::Ideal-------------------------------------
1822 //
1823 // If the previous store is to the same address as this load,
1824 // and the value stored was larger than a byte, replace this load
1825 // with the value stored truncated to a byte. If no truncation is
1826 // needed, the replacement is done in LoadNode::Identity().
1827 //
1828 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
1829 Node* mem = in(MemNode::Memory);
1830 Node* value = can_see_stored_value(mem, phase);
1831 if (value && !phase->type(value)->higher_equal(_type))
1832 return new (phase->C) AndINode(value, phase->intcon(0xFF));
1833 // Identity call will handle the case where truncation is not needed.
1834 return LoadNode::Ideal(phase, can_reshape);
1835 }
1836
1837 const Type* LoadUBNode::Value(PhaseTransform *phase) const {
1838 Node* mem = in(MemNode::Memory);
1839 Node* value = can_see_stored_value(mem,phase);
1840 if (value != NULL && value->is_Con() &&
1841 !value->bottom_type()->higher_equal(_type)) {
1842 // If the input to the store does not fit with the load's result type,
1843 // it must be truncated. We can't delay until Ideal call since
1844 // a singleton Value is needed for split_thru_phi optimization.
1845 int con = value->get_int();
1846 return TypeInt::make(con & 0xFF);
1847 }
1848 return LoadNode::Value(phase);
1849 }
1850
1851 //--------------------------LoadUSNode::Ideal-------------------------------------
1852 //
1853 // If the previous store is to the same address as this load,
1854 // and the value stored was larger than a char, replace this load
1855 // with the value stored truncated to a char. If no truncation is
1856 // needed, the replacement is done in LoadNode::Identity().
1857 //
1858 Node *LoadUSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1859 Node* mem = in(MemNode::Memory);
1860 Node* value = can_see_stored_value(mem,phase);
1861 if( value && !phase->type(value)->higher_equal( _type ) )
1862 return new (phase->C) AndINode(value,phase->intcon(0xFFFF));
1863 // Identity call will handle the case where truncation is not needed.
1864 return LoadNode::Ideal(phase, can_reshape);
1865 }
1866
1867 const Type* LoadUSNode::Value(PhaseTransform *phase) const {
1868 Node* mem = in(MemNode::Memory);
1869 Node* value = can_see_stored_value(mem,phase);
1870 if (value != NULL && value->is_Con() &&
1871 !value->bottom_type()->higher_equal(_type)) {
1872 // If the input to the store does not fit with the load's result type,
1873 // it must be truncated. We can't delay until Ideal call since
1874 // a singleton Value is needed for split_thru_phi optimization.
1875 int con = value->get_int();
1876 return TypeInt::make(con & 0xFFFF);
1877 }
1878 return LoadNode::Value(phase);
1879 }
1880
1881 //--------------------------LoadSNode::Ideal--------------------------------------
1882 //
1883 // If the previous store is to the same address as this load,
1884 // and the value stored was larger than a short, replace this load
1885 // with the value stored truncated to a short. If no truncation is
1886 // needed, the replacement is done in LoadNode::Identity().
1887 //
1888 Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1889 Node* mem = in(MemNode::Memory);
1890 Node* value = can_see_stored_value(mem,phase);
1891 if( value && !phase->type(value)->higher_equal( _type ) ) {
1892 Node *result = phase->transform( new (phase->C) LShiftINode(value, phase->intcon(16)) );
1893 return new (phase->C) RShiftINode(result, phase->intcon(16));
1894 }
1895 // Identity call will handle the case where truncation is not needed.
1896 return LoadNode::Ideal(phase, can_reshape);
1897 }
1898
1899 const Type* LoadSNode::Value(PhaseTransform *phase) const {
1900 Node* mem = in(MemNode::Memory);
1901 Node* value = can_see_stored_value(mem,phase);
1902 if (value != NULL && value->is_Con() &&
1903 !value->bottom_type()->higher_equal(_type)) {
1904 // If the input to the store does not fit with the load's result type,
1905 // it must be truncated. We can't delay until Ideal call since
1906 // a singleton Value is needed for split_thru_phi optimization.
1907 int con = value->get_int();
1908 return TypeInt::make((con << 16) >> 16);
1909 }
1910 return LoadNode::Value(phase);
1911 }
1912
1913 //=============================================================================
1914 //----------------------------LoadKlassNode::make------------------------------
1915 // Polymorphic factory method:
1916 Node *LoadKlassNode::make( PhaseGVN& gvn, Node *mem, Node *adr, const TypePtr* at, const TypeKlassPtr *tk ) {
1917 Compile* C = gvn.C;
1918 Node *ctl = NULL;
1919 // sanity check the alias category against the created node type
1920 const TypePtr *adr_type = adr->bottom_type()->isa_ptr();
1921 assert(adr_type != NULL, "expecting TypeKlassPtr");
1922 #ifdef _LP64
1923 if (adr_type->is_ptr_to_narrowklass()) {
1924 assert(UseCompressedKlassPointers, "no compressed klasses");
1925 Node* load_klass = gvn.transform(new (C) LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowklass()));
1926 return new (C) DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr());
1927 }
1928 #endif
1929 assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
1930 return new (C) LoadKlassNode(ctl, mem, adr, at, tk);
1931 }
1932
1933 //------------------------------Value------------------------------------------
1934 const Type *LoadKlassNode::Value( PhaseTransform *phase ) const {
1935 return klass_value_common(phase);
1936 }
1937
1938 const Type *LoadNode::klass_value_common( PhaseTransform *phase ) const {
1939 // Either input is TOP ==> the result is TOP
1940 const Type *t1 = phase->type( in(MemNode::Memory) );
1941 if (t1 == Type::TOP) return Type::TOP;
1942 Node *adr = in(MemNode::Address);
1943 const Type *t2 = phase->type( adr );
1944 if (t2 == Type::TOP) return Type::TOP;
1945 const TypePtr *tp = t2->is_ptr();
1946 if (TypePtr::above_centerline(tp->ptr()) ||
1947 tp->ptr() == TypePtr::Null) return Type::TOP;
1948
1949 // Return a more precise klass, if possible
1950 const TypeInstPtr *tinst = tp->isa_instptr();
1951 if (tinst != NULL) {
1952 ciInstanceKlass* ik = tinst->klass()->as_instance_klass();
1953 int offset = tinst->offset();
1954 if (ik == phase->C->env()->Class_klass()
1955 && (offset == java_lang_Class::klass_offset_in_bytes() ||
1956 offset == java_lang_Class::array_klass_offset_in_bytes())) {
1957 // We are loading a special hidden field from a Class mirror object,
1958 // the field which points to the VM's Klass metaobject.
1959 ciType* t = tinst->java_mirror_type();
1960 // java_mirror_type returns non-null for compile-time Class constants.
1961 if (t != NULL) {
1962 // constant oop => constant klass
1963 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
1964 return TypeKlassPtr::make(ciArrayKlass::make(t));
1965 }
1966 if (!t->is_klass()) {
1967 // a primitive Class (e.g., int.class) has NULL for a klass field
1968 return TypePtr::NULL_PTR;
1969 }
1970 // (Folds up the 1st indirection in aClassConstant.getModifiers().)
1971 return TypeKlassPtr::make(t->as_klass());
1972 }
1973 // non-constant mirror, so we can't tell what's going on
1974 }
1975 if( !ik->is_loaded() )
1976 return _type; // Bail out if not loaded
1977 if (offset == oopDesc::klass_offset_in_bytes()) {
1978 if (tinst->klass_is_exact()) {
1979 return TypeKlassPtr::make(ik);
1980 }
1981 // See if we can become precise: no subklasses and no interface
1982 // (Note: We need to support verified interfaces.)
1983 if (!ik->is_interface() && !ik->has_subklass()) {
1984 //assert(!UseExactTypes, "this code should be useless with exact types");
1985 // Add a dependence; if any subclass added we need to recompile
1986 if (!ik->is_final()) {
1987 // %%% should use stronger assert_unique_concrete_subtype instead
1988 phase->C->dependencies()->assert_leaf_type(ik);
1989 }
1990 // Return precise klass
1991 return TypeKlassPtr::make(ik);
1992 }
1993
1994 // Return root of possible klass
1995 return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/);
1996 }
1997 }
1998
1999 // Check for loading klass from an array
2000 const TypeAryPtr *tary = tp->isa_aryptr();
2001 if( tary != NULL ) {
2002 ciKlass *tary_klass = tary->klass();
2003 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP
2004 && tary->offset() == oopDesc::klass_offset_in_bytes()) {
2005 if (tary->klass_is_exact()) {
2006 return TypeKlassPtr::make(tary_klass);
2007 }
2008 ciArrayKlass *ak = tary->klass()->as_array_klass();
2009 // If the klass is an object array, we defer the question to the
2010 // array component klass.
2011 if( ak->is_obj_array_klass() ) {
2012 assert( ak->is_loaded(), "" );
2013 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass();
2014 if( base_k->is_loaded() && base_k->is_instance_klass() ) {
2015 ciInstanceKlass* ik = base_k->as_instance_klass();
2016 // See if we can become precise: no subklasses and no interface
2017 if (!ik->is_interface() && !ik->has_subklass()) {
2018 //assert(!UseExactTypes, "this code should be useless with exact types");
2019 // Add a dependence; if any subclass added we need to recompile
2020 if (!ik->is_final()) {
2021 phase->C->dependencies()->assert_leaf_type(ik);
2022 }
2023 // Return precise array klass
2024 return TypeKlassPtr::make(ak);
2025 }
2026 }
2027 return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/);
2028 } else { // Found a type-array?
2029 //assert(!UseExactTypes, "this code should be useless with exact types");
2030 assert( ak->is_type_array_klass(), "" );
2031 return TypeKlassPtr::make(ak); // These are always precise
2032 }
2033 }
2034 }
2035
2036 // Check for loading klass from an array klass
2037 const TypeKlassPtr *tkls = tp->isa_klassptr();
2038 if (tkls != NULL && !StressReflectiveCode) {
2039 ciKlass* klass = tkls->klass();
2040 if( !klass->is_loaded() )
2041 return _type; // Bail out if not loaded
2042 if( klass->is_obj_array_klass() &&
2043 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) {
2044 ciKlass* elem = klass->as_obj_array_klass()->element_klass();
2045 // // Always returning precise element type is incorrect,
2046 // // e.g., element type could be object and array may contain strings
2047 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
2048
2049 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
2050 // according to the element type's subclassing.
2051 return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/);
2052 }
2053 if( klass->is_instance_klass() && tkls->klass_is_exact() &&
2054 tkls->offset() == in_bytes(Klass::super_offset())) {
2055 ciKlass* sup = klass->as_instance_klass()->super();
2056 // The field is Klass::_super. Return its (constant) value.
2057 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
2058 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR;
2059 }
2060 }
2061
2062 // Bailout case
2063 return LoadNode::Value(phase);
2064 }
2065
2066 //------------------------------Identity---------------------------------------
2067 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
2068 // Also feed through the klass in Allocate(...klass...)._klass.
2069 Node* LoadKlassNode::Identity( PhaseTransform *phase ) {
2070 return klass_identity_common(phase);
2071 }
2072
2073 Node* LoadNode::klass_identity_common(PhaseTransform *phase ) {
2074 Node* x = LoadNode::Identity(phase);
2075 if (x != this) return x;
2076
2077 // Take apart the address into an oop and and offset.
2078 // Return 'this' if we cannot.
2079 Node* adr = in(MemNode::Address);
2080 intptr_t offset = 0;
2081 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2082 if (base == NULL) return this;
2083 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
2084 if (toop == NULL) return this;
2085
2086 // We can fetch the klass directly through an AllocateNode.
2087 // This works even if the klass is not constant (clone or newArray).
2088 if (offset == oopDesc::klass_offset_in_bytes()) {
2089 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
2090 if (allocated_klass != NULL) {
2091 return allocated_klass;
2092 }
2093 }
2094
2095 // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*.
2096 // Simplify ak.component_mirror.array_klass to plain ak, ak an ArrayKlass.
2097 // See inline_native_Class_query for occurrences of these patterns.
2098 // Java Example: x.getClass().isAssignableFrom(y)
2099 // Java Example: Array.newInstance(x.getClass().getComponentType(), n)
2100 //
2101 // This improves reflective code, often making the Class
2102 // mirror go completely dead. (Current exception: Class
2103 // mirrors may appear in debug info, but we could clean them out by
2104 // introducing a new debug info operator for Klass*.java_mirror).
2105 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass()
2106 && (offset == java_lang_Class::klass_offset_in_bytes() ||
2107 offset == java_lang_Class::array_klass_offset_in_bytes())) {
2108 // We are loading a special hidden field from a Class mirror,
2109 // the field which points to its Klass or ArrayKlass metaobject.
2110 if (base->is_Load()) {
2111 Node* adr2 = base->in(MemNode::Address);
2112 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2113 if (tkls != NULL && !tkls->empty()
2114 && (tkls->klass()->is_instance_klass() ||
2115 tkls->klass()->is_array_klass())
2116 && adr2->is_AddP()
2117 ) {
2118 int mirror_field = in_bytes(Klass::java_mirror_offset());
2119 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
2120 mirror_field = in_bytes(ArrayKlass::component_mirror_offset());
2121 }
2122 if (tkls->offset() == mirror_field) {
2123 return adr2->in(AddPNode::Base);
2124 }
2125 }
2126 }
2127 }
2128
2129 return this;
2130 }
2131
2132
2133 //------------------------------Value------------------------------------------
2134 const Type *LoadNKlassNode::Value( PhaseTransform *phase ) const {
2135 const Type *t = klass_value_common(phase);
2136 if (t == Type::TOP)
2137 return t;
2138
2139 return t->make_narrowklass();
2140 }
2141
2142 //------------------------------Identity---------------------------------------
2143 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
2144 // Also feed through the klass in Allocate(...klass...)._klass.
2145 Node* LoadNKlassNode::Identity( PhaseTransform *phase ) {
2146 Node *x = klass_identity_common(phase);
2147
2148 const Type *t = phase->type( x );
2149 if( t == Type::TOP ) return x;
2150 if( t->isa_narrowklass()) return x;
2151 assert (!t->isa_narrowoop(), "no narrow oop here");
2152
2153 return phase->transform(new (phase->C) EncodePKlassNode(x, t->make_narrowklass()));
2154 }
2155
2156 //------------------------------Value-----------------------------------------
2157 const Type *LoadRangeNode::Value( PhaseTransform *phase ) const {
2158 // Either input is TOP ==> the result is TOP
2159 const Type *t1 = phase->type( in(MemNode::Memory) );
2160 if( t1 == Type::TOP ) return Type::TOP;
2161 Node *adr = in(MemNode::Address);
2162 const Type *t2 = phase->type( adr );
2163 if( t2 == Type::TOP ) return Type::TOP;
2164 const TypePtr *tp = t2->is_ptr();
2165 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
2166 const TypeAryPtr *tap = tp->isa_aryptr();
2167 if( !tap ) return _type;
2168 return tap->size();
2169 }
2170
2171 //-------------------------------Ideal---------------------------------------
2172 // Feed through the length in AllocateArray(...length...)._length.
2173 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2174 Node* p = MemNode::Ideal_common(phase, can_reshape);
2175 if (p) return (p == NodeSentinel) ? NULL : p;
2176
2177 // Take apart the address into an oop and and offset.
2178 // Return 'this' if we cannot.
2179 Node* adr = in(MemNode::Address);
2180 intptr_t offset = 0;
2181 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2182 if (base == NULL) return NULL;
2183 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2184 if (tary == NULL) return NULL;
2185
2186 // We can fetch the length directly through an AllocateArrayNode.
2187 // This works even if the length is not constant (clone or newArray).
2188 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2189 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2190 if (alloc != NULL) {
2191 Node* allocated_length = alloc->Ideal_length();
2192 Node* len = alloc->make_ideal_length(tary, phase);
2193 if (allocated_length != len) {
2194 // New CastII improves on this.
2195 return len;
2196 }
2197 }
2198 }
2199
2200 return NULL;
2201 }
2202
2203 //------------------------------Identity---------------------------------------
2204 // Feed through the length in AllocateArray(...length...)._length.
2205 Node* LoadRangeNode::Identity( PhaseTransform *phase ) {
2206 Node* x = LoadINode::Identity(phase);
2207 if (x != this) return x;
2208
2209 // Take apart the address into an oop and and offset.
2210 // Return 'this' if we cannot.
2211 Node* adr = in(MemNode::Address);
2212 intptr_t offset = 0;
2213 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2214 if (base == NULL) return this;
2215 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2216 if (tary == NULL) return this;
2217
2218 // We can fetch the length directly through an AllocateArrayNode.
2219 // This works even if the length is not constant (clone or newArray).
2220 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2221 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2222 if (alloc != NULL) {
2223 Node* allocated_length = alloc->Ideal_length();
2224 // Do not allow make_ideal_length to allocate a CastII node.
2225 Node* len = alloc->make_ideal_length(tary, phase, false);
2226 if (allocated_length == len) {
2227 // Return allocated_length only if it would not be improved by a CastII.
2228 return allocated_length;
2229 }
2230 }
2231 }
2232
2233 return this;
2234
2235 }
2236
2237 //=============================================================================
2238 //---------------------------StoreNode::make-----------------------------------
2239 // Polymorphic factory method:
2240 StoreNode* StoreNode::make( PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt ) {
2241 Compile* C = gvn.C;
2242 assert( C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2243 ctl != NULL, "raw memory operations should have control edge");
2244
2245 switch (bt) {
2246 case T_BOOLEAN:
2247 case T_BYTE: return new (C) StoreBNode(ctl, mem, adr, adr_type, val);
2248 case T_INT: return new (C) StoreINode(ctl, mem, adr, adr_type, val);
2249 case T_CHAR:
2250 case T_SHORT: return new (C) StoreCNode(ctl, mem, adr, adr_type, val);
2251 case T_LONG: return new (C) StoreLNode(ctl, mem, adr, adr_type, val);
2252 case T_FLOAT: return new (C) StoreFNode(ctl, mem, adr, adr_type, val);
2253 case T_DOUBLE: return new (C) StoreDNode(ctl, mem, adr, adr_type, val);
2254 case T_METADATA:
2255 case T_ADDRESS:
2256 case T_OBJECT:
2257 #ifdef _LP64
2258 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
2259 val = gvn.transform(new (C) EncodePNode(val, val->bottom_type()->make_narrowoop()));
2260 return new (C) StoreNNode(ctl, mem, adr, adr_type, val);
2261 } else if (adr->bottom_type()->is_ptr_to_narrowklass() ||
2262 (UseCompressedKlassPointers && val->bottom_type()->isa_klassptr() &&
2263 adr->bottom_type()->isa_rawptr())) {
2264 val = gvn.transform(new (C) EncodePKlassNode(val, val->bottom_type()->make_narrowklass()));
2265 return new (C) StoreNKlassNode(ctl, mem, adr, adr_type, val);
2266 }
2267 #endif
2268 {
2269 return new (C) StorePNode(ctl, mem, adr, adr_type, val);
2270 }
2271 }
2272 ShouldNotReachHere();
2273 return (StoreNode*)NULL;
2274 }
2275
2276 StoreLNode* StoreLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val) {
2277 bool require_atomic = true;
2278 return new (C) StoreLNode(ctl, mem, adr, adr_type, val, require_atomic);
2279 }
2280
2281
2282 //--------------------------bottom_type----------------------------------------
2283 const Type *StoreNode::bottom_type() const {
2284 return Type::MEMORY;
2285 }
2286
2287 //------------------------------hash-------------------------------------------
2288 uint StoreNode::hash() const {
2289 // unroll addition of interesting fields
2290 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2291
2292 // Since they are not commoned, do not hash them:
2293 return NO_HASH;
2294 }
2295
2296 //------------------------------Ideal------------------------------------------
2297 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
2298 // When a store immediately follows a relevant allocation/initialization,
2299 // try to capture it into the initialization, or hoist it above.
2300 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2301 Node* p = MemNode::Ideal_common(phase, can_reshape);
2302 if (p) return (p == NodeSentinel) ? NULL : p;
2303
2304 Node* mem = in(MemNode::Memory);
2305 Node* address = in(MemNode::Address);
2306
2307 // Back-to-back stores to same address? Fold em up. Generally
2308 // unsafe if I have intervening uses... Also disallowed for StoreCM
2309 // since they must follow each StoreP operation. Redundant StoreCMs
2310 // are eliminated just before matching in final_graph_reshape.
2311 if (mem->is_Store() && mem->in(MemNode::Address)->eqv_uncast(address) &&
2312 mem->Opcode() != Op_StoreCM) {
2313 // Looking at a dead closed cycle of memory?
2314 assert(mem != mem->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
2315
2316 assert(Opcode() == mem->Opcode() ||
2317 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw,
2318 "no mismatched stores, except on raw memory");
2319
2320 if (mem->outcnt() == 1 && // check for intervening uses
2321 mem->as_Store()->memory_size() <= this->memory_size()) {
2322 // If anybody other than 'this' uses 'mem', we cannot fold 'mem' away.
2323 // For example, 'mem' might be the final state at a conditional return.
2324 // Or, 'mem' might be used by some node which is live at the same time
2325 // 'this' is live, which might be unschedulable. So, require exactly
2326 // ONE user, the 'this' store, until such time as we clone 'mem' for
2327 // each of 'mem's uses (thus making the exactly-1-user-rule hold true).
2328 if (can_reshape) { // (%%% is this an anachronism?)
2329 set_req_X(MemNode::Memory, mem->in(MemNode::Memory),
2330 phase->is_IterGVN());
2331 } else {
2332 // It's OK to do this in the parser, since DU info is always accurate,
2333 // and the parser always refers to nodes via SafePointNode maps.
2334 set_req(MemNode::Memory, mem->in(MemNode::Memory));
2335 }
2336 return this;
2337 }
2338 }
2339
2340 // Capture an unaliased, unconditional, simple store into an initializer.
2341 // Or, if it is independent of the allocation, hoist it above the allocation.
2342 if (ReduceFieldZeroing && /*can_reshape &&*/
2343 mem->is_Proj() && mem->in(0)->is_Initialize()) {
2344 InitializeNode* init = mem->in(0)->as_Initialize();
2345 intptr_t offset = init->can_capture_store(this, phase, can_reshape);
2346 if (offset > 0) {
2347 Node* moved = init->capture_store(this, offset, phase, can_reshape);
2348 // If the InitializeNode captured me, it made a raw copy of me,
2349 // and I need to disappear.
2350 if (moved != NULL) {
2351 // %%% hack to ensure that Ideal returns a new node:
2352 mem = MergeMemNode::make(phase->C, mem);
2353 return mem; // fold me away
2354 }
2355 }
2356 }
2357
2358 return NULL; // No further progress
2359 }
2360
2361 //------------------------------Value-----------------------------------------
2362 const Type *StoreNode::Value( PhaseTransform *phase ) const {
2363 // Either input is TOP ==> the result is TOP
2364 const Type *t1 = phase->type( in(MemNode::Memory) );
2365 if( t1 == Type::TOP ) return Type::TOP;
2366 const Type *t2 = phase->type( in(MemNode::Address) );
2367 if( t2 == Type::TOP ) return Type::TOP;
2368 const Type *t3 = phase->type( in(MemNode::ValueIn) );
2369 if( t3 == Type::TOP ) return Type::TOP;
2370 return Type::MEMORY;
2371 }
2372
2373 //------------------------------Identity---------------------------------------
2374 // Remove redundant stores:
2375 // Store(m, p, Load(m, p)) changes to m.
2376 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
2377 Node *StoreNode::Identity( PhaseTransform *phase ) {
2378 Node* mem = in(MemNode::Memory);
2379 Node* adr = in(MemNode::Address);
2380 Node* val = in(MemNode::ValueIn);
2381
2382 // Load then Store? Then the Store is useless
2383 if (val->is_Load() &&
2384 val->in(MemNode::Address)->eqv_uncast(adr) &&
2385 val->in(MemNode::Memory )->eqv_uncast(mem) &&
2386 val->as_Load()->store_Opcode() == Opcode()) {
2387 return mem;
2388 }
2389
2390 // Two stores in a row of the same value?
2391 if (mem->is_Store() &&
2392 mem->in(MemNode::Address)->eqv_uncast(adr) &&
2393 mem->in(MemNode::ValueIn)->eqv_uncast(val) &&
2394 mem->Opcode() == Opcode()) {
2395 return mem;
2396 }
2397
2398 // Store of zero anywhere into a freshly-allocated object?
2399 // Then the store is useless.
2400 // (It must already have been captured by the InitializeNode.)
2401 if (ReduceFieldZeroing && phase->type(val)->is_zero_type()) {
2402 // a newly allocated object is already all-zeroes everywhere
2403 if (mem->is_Proj() && mem->in(0)->is_Allocate()) {
2404 return mem;
2405 }
2406
2407 // the store may also apply to zero-bits in an earlier object
2408 Node* prev_mem = find_previous_store(phase);
2409 // Steps (a), (b): Walk past independent stores to find an exact match.
2410 if (prev_mem != NULL) {
2411 Node* prev_val = can_see_stored_value(prev_mem, phase);
2412 if (prev_val != NULL && phase->eqv(prev_val, val)) {
2413 // prev_val and val might differ by a cast; it would be good
2414 // to keep the more informative of the two.
2415 return mem;
2416 }
2417 }
2418 }
2419
2420 return this;
2421 }
2422
2423 //------------------------------match_edge-------------------------------------
2424 // Do we Match on this edge index or not? Match only memory & value
2425 uint StoreNode::match_edge(uint idx) const {
2426 return idx == MemNode::Address || idx == MemNode::ValueIn;
2427 }
2428
2429 //------------------------------cmp--------------------------------------------
2430 // Do not common stores up together. They generally have to be split
2431 // back up anyways, so do not bother.
2432 uint StoreNode::cmp( const Node &n ) const {
2433 return (&n == this); // Always fail except on self
2434 }
2435
2436 //------------------------------Ideal_masked_input-----------------------------
2437 // Check for a useless mask before a partial-word store
2438 // (StoreB ... (AndI valIn conIa) )
2439 // If (conIa & mask == mask) this simplifies to
2440 // (StoreB ... (valIn) )
2441 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
2442 Node *val = in(MemNode::ValueIn);
2443 if( val->Opcode() == Op_AndI ) {
2444 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2445 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
2446 set_req(MemNode::ValueIn, val->in(1));
2447 return this;
2448 }
2449 }
2450 return NULL;
2451 }
2452
2453
2454 //------------------------------Ideal_sign_extended_input----------------------
2455 // Check for useless sign-extension before a partial-word store
2456 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) )
2457 // If (conIL == conIR && conIR <= num_bits) this simplifies to
2458 // (StoreB ... (valIn) )
2459 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) {
2460 Node *val = in(MemNode::ValueIn);
2461 if( val->Opcode() == Op_RShiftI ) {
2462 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2463 if( t && t->is_con() && (t->get_con() <= num_bits) ) {
2464 Node *shl = val->in(1);
2465 if( shl->Opcode() == Op_LShiftI ) {
2466 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int();
2467 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) {
2468 set_req(MemNode::ValueIn, shl->in(1));
2469 return this;
2470 }
2471 }
2472 }
2473 }
2474 return NULL;
2475 }
2476
2477 //------------------------------value_never_loaded-----------------------------------
2478 // Determine whether there are any possible loads of the value stored.
2479 // For simplicity, we actually check if there are any loads from the
2480 // address stored to, not just for loads of the value stored by this node.
2481 //
2482 bool StoreNode::value_never_loaded( PhaseTransform *phase) const {
2483 Node *adr = in(Address);
2484 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
2485 if (adr_oop == NULL)
2486 return false;
2487 if (!adr_oop->is_known_instance_field())
2488 return false; // if not a distinct instance, there may be aliases of the address
2489 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
2490 Node *use = adr->fast_out(i);
2491 int opc = use->Opcode();
2492 if (use->is_Load() || use->is_LoadStore()) {
2493 return false;
2494 }
2495 }
2496 return true;
2497 }
2498
2499 //=============================================================================
2500 //------------------------------Ideal------------------------------------------
2501 // If the store is from an AND mask that leaves the low bits untouched, then
2502 // we can skip the AND operation. If the store is from a sign-extension
2503 // (a left shift, then right shift) we can skip both.
2504 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
2505 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
2506 if( progress != NULL ) return progress;
2507
2508 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
2509 if( progress != NULL ) return progress;
2510
2511 // Finally check the default case
2512 return StoreNode::Ideal(phase, can_reshape);
2513 }
2514
2515 //=============================================================================
2516 //------------------------------Ideal------------------------------------------
2517 // If the store is from an AND mask that leaves the low bits untouched, then
2518 // we can skip the AND operation
2519 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
2520 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
2521 if( progress != NULL ) return progress;
2522
2523 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
2524 if( progress != NULL ) return progress;
2525
2526 // Finally check the default case
2527 return StoreNode::Ideal(phase, can_reshape);
2528 }
2529
2530 //=============================================================================
2531 //------------------------------Identity---------------------------------------
2532 Node *StoreCMNode::Identity( PhaseTransform *phase ) {
2533 // No need to card mark when storing a null ptr
2534 Node* my_store = in(MemNode::OopStore);
2535 if (my_store->is_Store()) {
2536 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) );
2537 if( t1 == TypePtr::NULL_PTR ) {
2538 return in(MemNode::Memory);
2539 }
2540 }
2541 return this;
2542 }
2543
2544 //=============================================================================
2545 //------------------------------Ideal---------------------------------------
2546 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){
2547 Node* progress = StoreNode::Ideal(phase, can_reshape);
2548 if (progress != NULL) return progress;
2549
2550 Node* my_store = in(MemNode::OopStore);
2551 if (my_store->is_MergeMem()) {
2552 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx());
2553 set_req(MemNode::OopStore, mem);
2554 return this;
2555 }
2556
2557 return NULL;
2558 }
2559
2560 //------------------------------Value-----------------------------------------
2561 const Type *StoreCMNode::Value( PhaseTransform *phase ) const {
2562 // Either input is TOP ==> the result is TOP
2563 const Type *t = phase->type( in(MemNode::Memory) );
2564 if( t == Type::TOP ) return Type::TOP;
2565 t = phase->type( in(MemNode::Address) );
2566 if( t == Type::TOP ) return Type::TOP;
2567 t = phase->type( in(MemNode::ValueIn) );
2568 if( t == Type::TOP ) return Type::TOP;
2569 // If extra input is TOP ==> the result is TOP
2570 t = phase->type( in(MemNode::OopStore) );
2571 if( t == Type::TOP ) return Type::TOP;
2572
2573 return StoreNode::Value( phase );
2574 }
2575
2576
2577 //=============================================================================
2578 //----------------------------------SCMemProjNode------------------------------
2579 const Type * SCMemProjNode::Value( PhaseTransform *phase ) const
2580 {
2581 return bottom_type();
2582 }
2583
2584 //=============================================================================
2585 //----------------------------------LoadStoreNode------------------------------
2586 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required )
2587 : Node(required),
2588 _type(rt),
2589 _adr_type(at)
2590 {
2591 init_req(MemNode::Control, c );
2592 init_req(MemNode::Memory , mem);
2593 init_req(MemNode::Address, adr);
2594 init_req(MemNode::ValueIn, val);
2595 init_class_id(Class_LoadStore);
2596 }
2597
2598 uint LoadStoreNode::ideal_reg() const {
2599 return _type->ideal_reg();
2600 }
2601
2602 bool LoadStoreNode::result_not_used() const {
2603 for( DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++ ) {
2604 Node *x = fast_out(i);
2605 if (x->Opcode() == Op_SCMemProj) continue;
2606 return false;
2607 }
2608 return true;
2609 }
2610
2611 uint LoadStoreNode::size_of() const { return sizeof(*this); }
2612
2613 //=============================================================================
2614 //----------------------------------LoadStoreConditionalNode--------------------
2615 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, NULL, TypeInt::BOOL, 5) {
2616 init_req(ExpectedIn, ex );
2617 }
2618
2619 //=============================================================================
2620 //-------------------------------adr_type--------------------------------------
2621 // Do we Match on this edge index or not? Do not match memory
2622 const TypePtr* ClearArrayNode::adr_type() const {
2623 Node *adr = in(3);
2624 return MemNode::calculate_adr_type(adr->bottom_type());
2625 }
2626
2627 //------------------------------match_edge-------------------------------------
2628 // Do we Match on this edge index or not? Do not match memory
2629 uint ClearArrayNode::match_edge(uint idx) const {
2630 return idx > 1;
2631 }
2632
2633 //------------------------------Identity---------------------------------------
2634 // Clearing a zero length array does nothing
2635 Node *ClearArrayNode::Identity( PhaseTransform *phase ) {
2636 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
2637 }
2638
2639 //------------------------------Idealize---------------------------------------
2640 // Clearing a short array is faster with stores
2641 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape){
2642 const int unit = BytesPerLong;
2643 const TypeX* t = phase->type(in(2))->isa_intptr_t();
2644 if (!t) return NULL;
2645 if (!t->is_con()) return NULL;
2646 intptr_t raw_count = t->get_con();
2647 intptr_t size = raw_count;
2648 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
2649 // Clearing nothing uses the Identity call.
2650 // Negative clears are possible on dead ClearArrays
2651 // (see jck test stmt114.stmt11402.val).
2652 if (size <= 0 || size % unit != 0) return NULL;
2653 intptr_t count = size / unit;
2654 // Length too long; use fast hardware clear
2655 if (size > Matcher::init_array_short_size) return NULL;
2656 Node *mem = in(1);
2657 if( phase->type(mem)==Type::TOP ) return NULL;
2658 Node *adr = in(3);
2659 const Type* at = phase->type(adr);
2660 if( at==Type::TOP ) return NULL;
2661 const TypePtr* atp = at->isa_ptr();
2662 // adjust atp to be the correct array element address type
2663 if (atp == NULL) atp = TypePtr::BOTTOM;
2664 else atp = atp->add_offset(Type::OffsetBot);
2665 // Get base for derived pointer purposes
2666 if( adr->Opcode() != Op_AddP ) Unimplemented();
2667 Node *base = adr->in(1);
2668
2669 Node *zero = phase->makecon(TypeLong::ZERO);
2670 Node *off = phase->MakeConX(BytesPerLong);
2671 mem = new (phase->C) StoreLNode(in(0),mem,adr,atp,zero);
2672 count--;
2673 while( count-- ) {
2674 mem = phase->transform(mem);
2675 adr = phase->transform(new (phase->C) AddPNode(base,adr,off));
2676 mem = new (phase->C) StoreLNode(in(0),mem,adr,atp,zero);
2677 }
2678 return mem;
2679 }
2680
2681 //----------------------------step_through----------------------------------
2682 // Return allocation input memory edge if it is different instance
2683 // or itself if it is the one we are looking for.
2684 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) {
2685 Node* n = *np;
2686 assert(n->is_ClearArray(), "sanity");
2687 intptr_t offset;
2688 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
2689 // This method is called only before Allocate nodes are expanded during
2690 // macro nodes expansion. Before that ClearArray nodes are only generated
2691 // in LibraryCallKit::generate_arraycopy() which follows allocations.
2692 assert(alloc != NULL, "should have allocation");
2693 if (alloc->_idx == instance_id) {
2694 // Can not bypass initialization of the instance we are looking for.
2695 return false;
2696 }
2697 // Otherwise skip it.
2698 InitializeNode* init = alloc->initialization();
2699 if (init != NULL)
2700 *np = init->in(TypeFunc::Memory);
2701 else
2702 *np = alloc->in(TypeFunc::Memory);
2703 return true;
2704 }
2705
2706 //----------------------------clear_memory-------------------------------------
2707 // Generate code to initialize object storage to zero.
2708 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2709 intptr_t start_offset,
2710 Node* end_offset,
2711 PhaseGVN* phase) {
2712 Compile* C = phase->C;
2713 intptr_t offset = start_offset;
2714
2715 int unit = BytesPerLong;
2716 if ((offset % unit) != 0) {
2717 Node* adr = new (C) AddPNode(dest, dest, phase->MakeConX(offset));
2718 adr = phase->transform(adr);
2719 const TypePtr* atp = TypeRawPtr::BOTTOM;
2720 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT);
2721 mem = phase->transform(mem);
2722 offset += BytesPerInt;
2723 }
2724 assert((offset % unit) == 0, "");
2725
2726 // Initialize the remaining stuff, if any, with a ClearArray.
2727 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase);
2728 }
2729
2730 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2731 Node* start_offset,
2732 Node* end_offset,
2733 PhaseGVN* phase) {
2734 if (start_offset == end_offset) {
2735 // nothing to do
2736 return mem;
2737 }
2738
2739 Compile* C = phase->C;
2740 int unit = BytesPerLong;
2741 Node* zbase = start_offset;
2742 Node* zend = end_offset;
2743
2744 // Scale to the unit required by the CPU:
2745 if (!Matcher::init_array_count_is_in_bytes) {
2746 Node* shift = phase->intcon(exact_log2(unit));
2747 zbase = phase->transform( new(C) URShiftXNode(zbase, shift) );
2748 zend = phase->transform( new(C) URShiftXNode(zend, shift) );
2749 }
2750
2751 // Bulk clear double-words
2752 Node* zsize = phase->transform( new(C) SubXNode(zend, zbase) );
2753 Node* adr = phase->transform( new(C) AddPNode(dest, dest, start_offset) );
2754 mem = new (C) ClearArrayNode(ctl, mem, zsize, adr);
2755 return phase->transform(mem);
2756 }
2757
2758 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2759 intptr_t start_offset,
2760 intptr_t end_offset,
2761 PhaseGVN* phase) {
2762 if (start_offset == end_offset) {
2763 // nothing to do
2764 return mem;
2765 }
2766
2767 Compile* C = phase->C;
2768 assert((end_offset % BytesPerInt) == 0, "odd end offset");
2769 intptr_t done_offset = end_offset;
2770 if ((done_offset % BytesPerLong) != 0) {
2771 done_offset -= BytesPerInt;
2772 }
2773 if (done_offset > start_offset) {
2774 mem = clear_memory(ctl, mem, dest,
2775 start_offset, phase->MakeConX(done_offset), phase);
2776 }
2777 if (done_offset < end_offset) { // emit the final 32-bit store
2778 Node* adr = new (C) AddPNode(dest, dest, phase->MakeConX(done_offset));
2779 adr = phase->transform(adr);
2780 const TypePtr* atp = TypeRawPtr::BOTTOM;
2781 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT);
2782 mem = phase->transform(mem);
2783 done_offset += BytesPerInt;
2784 }
2785 assert(done_offset == end_offset, "");
2786 return mem;
2787 }
2788
2789 //=============================================================================
2790 // Do not match memory edge.
2791 uint StrIntrinsicNode::match_edge(uint idx) const {
2792 return idx == 2 || idx == 3;
2793 }
2794
2795 //------------------------------Ideal------------------------------------------
2796 // Return a node which is more "ideal" than the current node. Strip out
2797 // control copies
2798 Node *StrIntrinsicNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2799 if (remove_dead_region(phase, can_reshape)) return this;
2800 // Don't bother trying to transform a dead node
2801 if (in(0) && in(0)->is_top()) return NULL;
2802
2803 if (can_reshape) {
2804 Node* mem = phase->transform(in(MemNode::Memory));
2805 // If transformed to a MergeMem, get the desired slice
2806 uint alias_idx = phase->C->get_alias_index(adr_type());
2807 mem = mem->is_MergeMem() ? mem->as_MergeMem()->memory_at(alias_idx) : mem;
2808 if (mem != in(MemNode::Memory)) {
2809 set_req(MemNode::Memory, mem);
2810 return this;
2811 }
2812 }
2813 return NULL;
2814 }
2815
2816 //------------------------------Value------------------------------------------
2817 const Type *StrIntrinsicNode::Value( PhaseTransform *phase ) const {
2818 if (in(0) && phase->type(in(0)) == Type::TOP) return Type::TOP;
2819 return bottom_type();
2820 }
2821
2822 //=============================================================================
2823 //------------------------------match_edge-------------------------------------
2824 // Do not match memory edge
2825 uint EncodeISOArrayNode::match_edge(uint idx) const {
2826 return idx == 2 || idx == 3; // EncodeISOArray src (Binary dst len)
2827 }
2828
2829 //------------------------------Ideal------------------------------------------
2830 // Return a node which is more "ideal" than the current node. Strip out
2831 // control copies
2832 Node *EncodeISOArrayNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2833 return remove_dead_region(phase, can_reshape) ? this : NULL;
2834 }
2835
2836 //------------------------------Value------------------------------------------
2837 const Type *EncodeISOArrayNode::Value(PhaseTransform *phase) const {
2838 if (in(0) && phase->type(in(0)) == Type::TOP) return Type::TOP;
2839 return bottom_type();
2840 }
2841
2842 //=============================================================================
2843 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
2844 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)),
2845 _adr_type(C->get_adr_type(alias_idx))
2846 {
2847 init_class_id(Class_MemBar);
2848 Node* top = C->top();
2849 init_req(TypeFunc::I_O,top);
2850 init_req(TypeFunc::FramePtr,top);
2851 init_req(TypeFunc::ReturnAdr,top);
2852 if (precedent != NULL)
2853 init_req(TypeFunc::Parms, precedent);
2854 }
2855
2856 //------------------------------cmp--------------------------------------------
2857 uint MemBarNode::hash() const { return NO_HASH; }
2858 uint MemBarNode::cmp( const Node &n ) const {
2859 return (&n == this); // Always fail except on self
2860 }
2861
2862 //------------------------------make-------------------------------------------
2863 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
2864 switch (opcode) {
2865 case Op_MemBarAcquire: return new(C) MemBarAcquireNode(C, atp, pn);
2866 case Op_MemBarRelease: return new(C) MemBarReleaseNode(C, atp, pn);
2867 case Op_MemBarAcquireLock: return new(C) MemBarAcquireLockNode(C, atp, pn);
2868 case Op_MemBarReleaseLock: return new(C) MemBarReleaseLockNode(C, atp, pn);
2869 case Op_MemBarVolatile: return new(C) MemBarVolatileNode(C, atp, pn);
2870 case Op_MemBarCPUOrder: return new(C) MemBarCPUOrderNode(C, atp, pn);
2871 case Op_Initialize: return new(C) InitializeNode(C, atp, pn);
2872 case Op_MemBarStoreStore: return new(C) MemBarStoreStoreNode(C, atp, pn);
2873 default: ShouldNotReachHere(); return NULL;
2874 }
2875 }
2876
2877 //------------------------------Ideal------------------------------------------
2878 // Return a node which is more "ideal" than the current node. Strip out
2879 // control copies
2880 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2881 if (remove_dead_region(phase, can_reshape)) return this;
2882 // Don't bother trying to transform a dead node
2883 if (in(0) && in(0)->is_top()) return NULL;
2884
2885 // Eliminate volatile MemBars for scalar replaced objects.
2886 if (can_reshape && req() == (Precedent+1) &&
2887 (Opcode() == Op_MemBarAcquire || Opcode() == Op_MemBarVolatile)) {
2888 // Volatile field loads and stores.
2889 Node* my_mem = in(MemBarNode::Precedent);
2890 if (my_mem != NULL && my_mem->is_Mem()) {
2891 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
2892 // Check for scalar replaced object reference.
2893 if( t_oop != NULL && t_oop->is_known_instance_field() &&
2894 t_oop->offset() != Type::OffsetBot &&
2895 t_oop->offset() != Type::OffsetTop) {
2896 // Replace MemBar projections by its inputs.
2897 PhaseIterGVN* igvn = phase->is_IterGVN();
2898 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
2899 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
2900 // Must return either the original node (now dead) or a new node
2901 // (Do not return a top here, since that would break the uniqueness of top.)
2902 return new (phase->C) ConINode(TypeInt::ZERO);
2903 }
2904 }
2905 }
2906 return NULL;
2907 }
2908
2909 //------------------------------Value------------------------------------------
2910 const Type *MemBarNode::Value( PhaseTransform *phase ) const {
2911 if( !in(0) ) return Type::TOP;
2912 if( phase->type(in(0)) == Type::TOP )
2913 return Type::TOP;
2914 return TypeTuple::MEMBAR;
2915 }
2916
2917 //------------------------------match------------------------------------------
2918 // Construct projections for memory.
2919 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) {
2920 switch (proj->_con) {
2921 case TypeFunc::Control:
2922 case TypeFunc::Memory:
2923 return new (m->C) MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
2924 }
2925 ShouldNotReachHere();
2926 return NULL;
2927 }
2928
2929 //===========================InitializeNode====================================
2930 // SUMMARY:
2931 // This node acts as a memory barrier on raw memory, after some raw stores.
2932 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
2933 // The Initialize can 'capture' suitably constrained stores as raw inits.
2934 // It can coalesce related raw stores into larger units (called 'tiles').
2935 // It can avoid zeroing new storage for memory units which have raw inits.
2936 // At macro-expansion, it is marked 'complete', and does not optimize further.
2937 //
2938 // EXAMPLE:
2939 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
2940 // ctl = incoming control; mem* = incoming memory
2941 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
2942 // First allocate uninitialized memory and fill in the header:
2943 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
2944 // ctl := alloc.Control; mem* := alloc.Memory*
2945 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
2946 // Then initialize to zero the non-header parts of the raw memory block:
2947 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
2948 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
2949 // After the initialize node executes, the object is ready for service:
2950 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
2951 // Suppose its body is immediately initialized as {1,2}:
2952 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
2953 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
2954 // mem.SLICE(#short[*]) := store2
2955 //
2956 // DETAILS:
2957 // An InitializeNode collects and isolates object initialization after
2958 // an AllocateNode and before the next possible safepoint. As a
2959 // memory barrier (MemBarNode), it keeps critical stores from drifting
2960 // down past any safepoint or any publication of the allocation.
2961 // Before this barrier, a newly-allocated object may have uninitialized bits.
2962 // After this barrier, it may be treated as a real oop, and GC is allowed.
2963 //
2964 // The semantics of the InitializeNode include an implicit zeroing of
2965 // the new object from object header to the end of the object.
2966 // (The object header and end are determined by the AllocateNode.)
2967 //
2968 // Certain stores may be added as direct inputs to the InitializeNode.
2969 // These stores must update raw memory, and they must be to addresses
2970 // derived from the raw address produced by AllocateNode, and with
2971 // a constant offset. They must be ordered by increasing offset.
2972 // The first one is at in(RawStores), the last at in(req()-1).
2973 // Unlike most memory operations, they are not linked in a chain,
2974 // but are displayed in parallel as users of the rawmem output of
2975 // the allocation.
2976 //
2977 // (See comments in InitializeNode::capture_store, which continue
2978 // the example given above.)
2979 //
2980 // When the associated Allocate is macro-expanded, the InitializeNode
2981 // may be rewritten to optimize collected stores. A ClearArrayNode
2982 // may also be created at that point to represent any required zeroing.
2983 // The InitializeNode is then marked 'complete', prohibiting further
2984 // capturing of nearby memory operations.
2985 //
2986 // During macro-expansion, all captured initializations which store
2987 // constant values of 32 bits or smaller are coalesced (if advantageous)
2988 // into larger 'tiles' 32 or 64 bits. This allows an object to be
2989 // initialized in fewer memory operations. Memory words which are
2990 // covered by neither tiles nor non-constant stores are pre-zeroed
2991 // by explicit stores of zero. (The code shape happens to do all
2992 // zeroing first, then all other stores, with both sequences occurring
2993 // in order of ascending offsets.)
2994 //
2995 // Alternatively, code may be inserted between an AllocateNode and its
2996 // InitializeNode, to perform arbitrary initialization of the new object.
2997 // E.g., the object copying intrinsics insert complex data transfers here.
2998 // The initialization must then be marked as 'complete' disable the
2999 // built-in zeroing semantics and the collection of initializing stores.
3000 //
3001 // While an InitializeNode is incomplete, reads from the memory state
3002 // produced by it are optimizable if they match the control edge and
3003 // new oop address associated with the allocation/initialization.
3004 // They return a stored value (if the offset matches) or else zero.
3005 // A write to the memory state, if it matches control and address,
3006 // and if it is to a constant offset, may be 'captured' by the
3007 // InitializeNode. It is cloned as a raw memory operation and rewired
3008 // inside the initialization, to the raw oop produced by the allocation.
3009 // Operations on addresses which are provably distinct (e.g., to
3010 // other AllocateNodes) are allowed to bypass the initialization.
3011 //
3012 // The effect of all this is to consolidate object initialization
3013 // (both arrays and non-arrays, both piecewise and bulk) into a
3014 // single location, where it can be optimized as a unit.
3015 //
3016 // Only stores with an offset less than TrackedInitializationLimit words
3017 // will be considered for capture by an InitializeNode. This puts a
3018 // reasonable limit on the complexity of optimized initializations.
3019
3020 //---------------------------InitializeNode------------------------------------
3021 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
3022 : _is_complete(Incomplete), _does_not_escape(false),
3023 MemBarNode(C, adr_type, rawoop)
3024 {
3025 init_class_id(Class_Initialize);
3026
3027 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
3028 assert(in(RawAddress) == rawoop, "proper init");
3029 // Note: allocation() can be NULL, for secondary initialization barriers
3030 }
3031
3032 // Since this node is not matched, it will be processed by the
3033 // register allocator. Declare that there are no constraints
3034 // on the allocation of the RawAddress edge.
3035 const RegMask &InitializeNode::in_RegMask(uint idx) const {
3036 // This edge should be set to top, by the set_complete. But be conservative.
3037 if (idx == InitializeNode::RawAddress)
3038 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
3039 return RegMask::Empty;
3040 }
3041
3042 Node* InitializeNode::memory(uint alias_idx) {
3043 Node* mem = in(Memory);
3044 if (mem->is_MergeMem()) {
3045 return mem->as_MergeMem()->memory_at(alias_idx);
3046 } else {
3047 // incoming raw memory is not split
3048 return mem;
3049 }
3050 }
3051
3052 bool InitializeNode::is_non_zero() {
3053 if (is_complete()) return false;
3054 remove_extra_zeroes();
3055 return (req() > RawStores);
3056 }
3057
3058 void InitializeNode::set_complete(PhaseGVN* phase) {
3059 assert(!is_complete(), "caller responsibility");
3060 _is_complete = Complete;
3061
3062 // After this node is complete, it contains a bunch of
3063 // raw-memory initializations. There is no need for
3064 // it to have anything to do with non-raw memory effects.
3065 // Therefore, tell all non-raw users to re-optimize themselves,
3066 // after skipping the memory effects of this initialization.
3067 PhaseIterGVN* igvn = phase->is_IterGVN();
3068 if (igvn) igvn->add_users_to_worklist(this);
3069 }
3070
3071 // convenience function
3072 // return false if the init contains any stores already
3073 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
3074 InitializeNode* init = initialization();
3075 if (init == NULL || init->is_complete()) return false;
3076 init->remove_extra_zeroes();
3077 // for now, if this allocation has already collected any inits, bail:
3078 if (init->is_non_zero()) return false;
3079 init->set_complete(phase);
3080 return true;
3081 }
3082
3083 void InitializeNode::remove_extra_zeroes() {
3084 if (req() == RawStores) return;
3085 Node* zmem = zero_memory();
3086 uint fill = RawStores;
3087 for (uint i = fill; i < req(); i++) {
3088 Node* n = in(i);
3089 if (n->is_top() || n == zmem) continue; // skip
3090 if (fill < i) set_req(fill, n); // compact
3091 ++fill;
3092 }
3093 // delete any empty spaces created:
3094 while (fill < req()) {
3095 del_req(fill);
3096 }
3097 }
3098
3099 // Helper for remembering which stores go with which offsets.
3100 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) {
3101 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
3102 intptr_t offset = -1;
3103 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
3104 phase, offset);
3105 if (base == NULL) return -1; // something is dead,
3106 if (offset < 0) return -1; // dead, dead
3107 return offset;
3108 }
3109
3110 // Helper for proving that an initialization expression is
3111 // "simple enough" to be folded into an object initialization.
3112 // Attempts to prove that a store's initial value 'n' can be captured
3113 // within the initialization without creating a vicious cycle, such as:
3114 // { Foo p = new Foo(); p.next = p; }
3115 // True for constants and parameters and small combinations thereof.
3116 bool InitializeNode::detect_init_independence(Node* n,
3117 bool st_is_pinned,
3118 int& count) {
3119 if (n == NULL) return true; // (can this really happen?)
3120 if (n->is_Proj()) n = n->in(0);
3121 if (n == this) return false; // found a cycle
3122 if (n->is_Con()) return true;
3123 if (n->is_Start()) return true; // params, etc., are OK
3124 if (n->is_Root()) return true; // even better
3125
3126 Node* ctl = n->in(0);
3127 if (ctl != NULL && !ctl->is_top()) {
3128 if (ctl->is_Proj()) ctl = ctl->in(0);
3129 if (ctl == this) return false;
3130
3131 // If we already know that the enclosing memory op is pinned right after
3132 // the init, then any control flow that the store has picked up
3133 // must have preceded the init, or else be equal to the init.
3134 // Even after loop optimizations (which might change control edges)
3135 // a store is never pinned *before* the availability of its inputs.
3136 if (!MemNode::all_controls_dominate(n, this))
3137 return false; // failed to prove a good control
3138
3139 }
3140
3141 // Check data edges for possible dependencies on 'this'.
3142 if ((count += 1) > 20) return false; // complexity limit
3143 for (uint i = 1; i < n->req(); i++) {
3144 Node* m = n->in(i);
3145 if (m == NULL || m == n || m->is_top()) continue;
3146 uint first_i = n->find_edge(m);
3147 if (i != first_i) continue; // process duplicate edge just once
3148 if (!detect_init_independence(m, st_is_pinned, count)) {
3149 return false;
3150 }
3151 }
3152
3153 return true;
3154 }
3155
3156 // Here are all the checks a Store must pass before it can be moved into
3157 // an initialization. Returns zero if a check fails.
3158 // On success, returns the (constant) offset to which the store applies,
3159 // within the initialized memory.
3160 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase, bool can_reshape) {
3161 const int FAIL = 0;
3162 if (st->req() != MemNode::ValueIn + 1)
3163 return FAIL; // an inscrutable StoreNode (card mark?)
3164 Node* ctl = st->in(MemNode::Control);
3165 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this))
3166 return FAIL; // must be unconditional after the initialization
3167 Node* mem = st->in(MemNode::Memory);
3168 if (!(mem->is_Proj() && mem->in(0) == this))
3169 return FAIL; // must not be preceded by other stores
3170 Node* adr = st->in(MemNode::Address);
3171 intptr_t offset;
3172 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
3173 if (alloc == NULL)
3174 return FAIL; // inscrutable address
3175 if (alloc != allocation())
3176 return FAIL; // wrong allocation! (store needs to float up)
3177 Node* val = st->in(MemNode::ValueIn);
3178 int complexity_count = 0;
3179 if (!detect_init_independence(val, true, complexity_count))
3180 return FAIL; // stored value must be 'simple enough'
3181
3182 // The Store can be captured only if nothing after the allocation
3183 // and before the Store is using the memory location that the store
3184 // overwrites.
3185 bool failed = false;
3186 // If is_complete_with_arraycopy() is true the shape of the graph is
3187 // well defined and is safe so no need for extra checks.
3188 if (!is_complete_with_arraycopy()) {
3189 // We are going to look at each use of the memory state following
3190 // the allocation to make sure nothing reads the memory that the
3191 // Store writes.
3192 const TypePtr* t_adr = phase->type(adr)->isa_ptr();
3193 int alias_idx = phase->C->get_alias_index(t_adr);
3194 ResourceMark rm;
3195 Unique_Node_List mems;
3196 mems.push(mem);
3197 Node* unique_merge = NULL;
3198 for (uint next = 0; next < mems.size(); ++next) {
3199 Node *m = mems.at(next);
3200 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
3201 Node *n = m->fast_out(j);
3202 if (n->outcnt() == 0) {
3203 continue;
3204 }
3205 if (n == st) {
3206 continue;
3207 } else if (n->in(0) != NULL && n->in(0) != ctl) {
3208 // If the control of this use is different from the control
3209 // of the Store which is right after the InitializeNode then
3210 // this node cannot be between the InitializeNode and the
3211 // Store.
3212 continue;
3213 } else if (n->is_MergeMem()) {
3214 if (n->as_MergeMem()->memory_at(alias_idx) == m) {
3215 // We can hit a MergeMemNode (that will likely go away
3216 // later) that is a direct use of the memory state
3217 // following the InitializeNode on the same slice as the
3218 // store node that we'd like to capture. We need to check
3219 // the uses of the MergeMemNode.
3220 mems.push(n);
3221 }
3222 } else if (n->is_Mem()) {
3223 Node* other_adr = n->in(MemNode::Address);
3224 if (other_adr == adr) {
3225 failed = true;
3226 break;
3227 } else {
3228 const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr();
3229 if (other_t_adr != NULL) {
3230 int other_alias_idx = phase->C->get_alias_index(other_t_adr);
3231 if (other_alias_idx == alias_idx) {
3232 // A load from the same memory slice as the store right
3233 // after the InitializeNode. We check the control of the
3234 // object/array that is loaded from. If it's the same as
3235 // the store control then we cannot capture the store.
3236 assert(!n->is_Store(), "2 stores to same slice on same control?");
3237 Node* base = other_adr;
3238 assert(base->is_AddP(), err_msg_res("should be addp but is %s", base->Name()));
3239 base = base->in(AddPNode::Base);
3240 if (base != NULL) {
3241 base = base->uncast();
3242 if (base->is_Proj() && base->in(0) == alloc) {
3243 failed = true;
3244 break;
3245 }
3246 }
3247 }
3248 }
3249 }
3250 } else {
3251 failed = true;
3252 break;
3253 }
3254 }
3255 }
3256 }
3257 if (failed) {
3258 if (!can_reshape) {
3259 // We decided we couldn't capture the store during parsing. We
3260 // should try again during the next IGVN once the graph is
3261 // cleaner.
3262 phase->C->record_for_igvn(st);
3263 }
3264 return FAIL;
3265 }
3266
3267 return offset; // success
3268 }
3269
3270 // Find the captured store in(i) which corresponds to the range
3271 // [start..start+size) in the initialized object.
3272 // If there is one, return its index i. If there isn't, return the
3273 // negative of the index where it should be inserted.
3274 // Return 0 if the queried range overlaps an initialization boundary
3275 // or if dead code is encountered.
3276 // If size_in_bytes is zero, do not bother with overlap checks.
3277 int InitializeNode::captured_store_insertion_point(intptr_t start,
3278 int size_in_bytes,
3279 PhaseTransform* phase) {
3280 const int FAIL = 0, MAX_STORE = BytesPerLong;
3281
3282 if (is_complete())
3283 return FAIL; // arraycopy got here first; punt
3284
3285 assert(allocation() != NULL, "must be present");
3286
3287 // no negatives, no header fields:
3288 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
3289
3290 // after a certain size, we bail out on tracking all the stores:
3291 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3292 if (start >= ti_limit) return FAIL;
3293
3294 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
3295 if (i >= limit) return -(int)i; // not found; here is where to put it
3296
3297 Node* st = in(i);
3298 intptr_t st_off = get_store_offset(st, phase);
3299 if (st_off < 0) {
3300 if (st != zero_memory()) {
3301 return FAIL; // bail out if there is dead garbage
3302 }
3303 } else if (st_off > start) {
3304 // ...we are done, since stores are ordered
3305 if (st_off < start + size_in_bytes) {
3306 return FAIL; // the next store overlaps
3307 }
3308 return -(int)i; // not found; here is where to put it
3309 } else if (st_off < start) {
3310 if (size_in_bytes != 0 &&
3311 start < st_off + MAX_STORE &&
3312 start < st_off + st->as_Store()->memory_size()) {
3313 return FAIL; // the previous store overlaps
3314 }
3315 } else {
3316 if (size_in_bytes != 0 &&
3317 st->as_Store()->memory_size() != size_in_bytes) {
3318 return FAIL; // mismatched store size
3319 }
3320 return i;
3321 }
3322
3323 ++i;
3324 }
3325 }
3326
3327 // Look for a captured store which initializes at the offset 'start'
3328 // with the given size. If there is no such store, and no other
3329 // initialization interferes, then return zero_memory (the memory
3330 // projection of the AllocateNode).
3331 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
3332 PhaseTransform* phase) {
3333 assert(stores_are_sane(phase), "");
3334 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3335 if (i == 0) {
3336 return NULL; // something is dead
3337 } else if (i < 0) {
3338 return zero_memory(); // just primordial zero bits here
3339 } else {
3340 Node* st = in(i); // here is the store at this position
3341 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
3342 return st;
3343 }
3344 }
3345
3346 // Create, as a raw pointer, an address within my new object at 'offset'.
3347 Node* InitializeNode::make_raw_address(intptr_t offset,
3348 PhaseTransform* phase) {
3349 Node* addr = in(RawAddress);
3350 if (offset != 0) {
3351 Compile* C = phase->C;
3352 addr = phase->transform( new (C) AddPNode(C->top(), addr,
3353 phase->MakeConX(offset)) );
3354 }
3355 return addr;
3356 }
3357
3358 // Clone the given store, converting it into a raw store
3359 // initializing a field or element of my new object.
3360 // Caller is responsible for retiring the original store,
3361 // with subsume_node or the like.
3362 //
3363 // From the example above InitializeNode::InitializeNode,
3364 // here are the old stores to be captured:
3365 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3366 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3367 //
3368 // Here is the changed code; note the extra edges on init:
3369 // alloc = (Allocate ...)
3370 // rawoop = alloc.RawAddress
3371 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
3372 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
3373 // init = (Initialize alloc.Control alloc.Memory rawoop
3374 // rawstore1 rawstore2)
3375 //
3376 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
3377 PhaseTransform* phase, bool can_reshape) {
3378 assert(stores_are_sane(phase), "");
3379
3380 if (start < 0) return NULL;
3381 assert(can_capture_store(st, phase, can_reshape) == start, "sanity");
3382
3383 Compile* C = phase->C;
3384 int size_in_bytes = st->memory_size();
3385 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3386 if (i == 0) return NULL; // bail out
3387 Node* prev_mem = NULL; // raw memory for the captured store
3388 if (i > 0) {
3389 prev_mem = in(i); // there is a pre-existing store under this one
3390 set_req(i, C->top()); // temporarily disconnect it
3391 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
3392 } else {
3393 i = -i; // no pre-existing store
3394 prev_mem = zero_memory(); // a slice of the newly allocated object
3395 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
3396 set_req(--i, C->top()); // reuse this edge; it has been folded away
3397 else
3398 ins_req(i, C->top()); // build a new edge
3399 }
3400 Node* new_st = st->clone();
3401 new_st->set_req(MemNode::Control, in(Control));
3402 new_st->set_req(MemNode::Memory, prev_mem);
3403 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
3404 new_st = phase->transform(new_st);
3405
3406 // At this point, new_st might have swallowed a pre-existing store
3407 // at the same offset, or perhaps new_st might have disappeared,
3408 // if it redundantly stored the same value (or zero to fresh memory).
3409
3410 // In any case, wire it in:
3411 set_req(i, new_st);
3412
3413 // The caller may now kill the old guy.
3414 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
3415 assert(check_st == new_st || check_st == NULL, "must be findable");
3416 assert(!is_complete(), "");
3417 return new_st;
3418 }
3419
3420 static bool store_constant(jlong* tiles, int num_tiles,
3421 intptr_t st_off, int st_size,
3422 jlong con) {
3423 if ((st_off & (st_size-1)) != 0)
3424 return false; // strange store offset (assume size==2**N)
3425 address addr = (address)tiles + st_off;
3426 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
3427 switch (st_size) {
3428 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
3429 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
3430 case sizeof(jint): *(jint*) addr = (jint) con; break;
3431 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
3432 default: return false; // strange store size (detect size!=2**N here)
3433 }
3434 return true; // return success to caller
3435 }
3436
3437 // Coalesce subword constants into int constants and possibly
3438 // into long constants. The goal, if the CPU permits,
3439 // is to initialize the object with a small number of 64-bit tiles.
3440 // Also, convert floating-point constants to bit patterns.
3441 // Non-constants are not relevant to this pass.
3442 //
3443 // In terms of the running example on InitializeNode::InitializeNode
3444 // and InitializeNode::capture_store, here is the transformation
3445 // of rawstore1 and rawstore2 into rawstore12:
3446 // alloc = (Allocate ...)
3447 // rawoop = alloc.RawAddress
3448 // tile12 = 0x00010002
3449 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
3450 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
3451 //
3452 void
3453 InitializeNode::coalesce_subword_stores(intptr_t header_size,
3454 Node* size_in_bytes,
3455 PhaseGVN* phase) {
3456 Compile* C = phase->C;
3457
3458 assert(stores_are_sane(phase), "");
3459 // Note: After this pass, they are not completely sane,
3460 // since there may be some overlaps.
3461
3462 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
3463
3464 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3465 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
3466 size_limit = MIN2(size_limit, ti_limit);
3467 size_limit = align_size_up(size_limit, BytesPerLong);
3468 int num_tiles = size_limit / BytesPerLong;
3469
3470 // allocate space for the tile map:
3471 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
3472 jlong tiles_buf[small_len];
3473 Node* nodes_buf[small_len];
3474 jlong inits_buf[small_len];
3475 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
3476 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3477 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
3478 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
3479 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
3480 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3481 // tiles: exact bitwise model of all primitive constants
3482 // nodes: last constant-storing node subsumed into the tiles model
3483 // inits: which bytes (in each tile) are touched by any initializations
3484
3485 //// Pass A: Fill in the tile model with any relevant stores.
3486
3487 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
3488 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
3489 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
3490 Node* zmem = zero_memory(); // initially zero memory state
3491 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3492 Node* st = in(i);
3493 intptr_t st_off = get_store_offset(st, phase);
3494
3495 // Figure out the store's offset and constant value:
3496 if (st_off < header_size) continue; //skip (ignore header)
3497 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
3498 int st_size = st->as_Store()->memory_size();
3499 if (st_off + st_size > size_limit) break;
3500
3501 // Record which bytes are touched, whether by constant or not.
3502 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
3503 continue; // skip (strange store size)
3504
3505 const Type* val = phase->type(st->in(MemNode::ValueIn));
3506 if (!val->singleton()) continue; //skip (non-con store)
3507 BasicType type = val->basic_type();
3508
3509 jlong con = 0;
3510 switch (type) {
3511 case T_INT: con = val->is_int()->get_con(); break;
3512 case T_LONG: con = val->is_long()->get_con(); break;
3513 case T_FLOAT: con = jint_cast(val->getf()); break;
3514 case T_DOUBLE: con = jlong_cast(val->getd()); break;
3515 default: continue; //skip (odd store type)
3516 }
3517
3518 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
3519 st->Opcode() == Op_StoreL) {
3520 continue; // This StoreL is already optimal.
3521 }
3522
3523 // Store down the constant.
3524 store_constant(tiles, num_tiles, st_off, st_size, con);
3525
3526 intptr_t j = st_off >> LogBytesPerLong;
3527
3528 if (type == T_INT && st_size == BytesPerInt
3529 && (st_off & BytesPerInt) == BytesPerInt) {
3530 jlong lcon = tiles[j];
3531 if (!Matcher::isSimpleConstant64(lcon) &&
3532 st->Opcode() == Op_StoreI) {
3533 // This StoreI is already optimal by itself.
3534 jint* intcon = (jint*) &tiles[j];
3535 intcon[1] = 0; // undo the store_constant()
3536
3537 // If the previous store is also optimal by itself, back up and
3538 // undo the action of the previous loop iteration... if we can.
3539 // But if we can't, just let the previous half take care of itself.
3540 st = nodes[j];
3541 st_off -= BytesPerInt;
3542 con = intcon[0];
3543 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) {
3544 assert(st_off >= header_size, "still ignoring header");
3545 assert(get_store_offset(st, phase) == st_off, "must be");
3546 assert(in(i-1) == zmem, "must be");
3547 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
3548 assert(con == tcon->is_int()->get_con(), "must be");
3549 // Undo the effects of the previous loop trip, which swallowed st:
3550 intcon[0] = 0; // undo store_constant()
3551 set_req(i-1, st); // undo set_req(i, zmem)
3552 nodes[j] = NULL; // undo nodes[j] = st
3553 --old_subword; // undo ++old_subword
3554 }
3555 continue; // This StoreI is already optimal.
3556 }
3557 }
3558
3559 // This store is not needed.
3560 set_req(i, zmem);
3561 nodes[j] = st; // record for the moment
3562 if (st_size < BytesPerLong) // something has changed
3563 ++old_subword; // includes int/float, but who's counting...
3564 else ++old_long;
3565 }
3566
3567 if ((old_subword + old_long) == 0)
3568 return; // nothing more to do
3569
3570 //// Pass B: Convert any non-zero tiles into optimal constant stores.
3571 // Be sure to insert them before overlapping non-constant stores.
3572 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
3573 for (int j = 0; j < num_tiles; j++) {
3574 jlong con = tiles[j];
3575 jlong init = inits[j];
3576 if (con == 0) continue;
3577 jint con0, con1; // split the constant, address-wise
3578 jint init0, init1; // split the init map, address-wise
3579 { union { jlong con; jint intcon[2]; } u;
3580 u.con = con;
3581 con0 = u.intcon[0];
3582 con1 = u.intcon[1];
3583 u.con = init;
3584 init0 = u.intcon[0];
3585 init1 = u.intcon[1];
3586 }
3587
3588 Node* old = nodes[j];
3589 assert(old != NULL, "need the prior store");
3590 intptr_t offset = (j * BytesPerLong);
3591
3592 bool split = !Matcher::isSimpleConstant64(con);
3593
3594 if (offset < header_size) {
3595 assert(offset + BytesPerInt >= header_size, "second int counts");
3596 assert(*(jint*)&tiles[j] == 0, "junk in header");
3597 split = true; // only the second word counts
3598 // Example: int a[] = { 42 ... }
3599 } else if (con0 == 0 && init0 == -1) {
3600 split = true; // first word is covered by full inits
3601 // Example: int a[] = { ... foo(), 42 ... }
3602 } else if (con1 == 0 && init1 == -1) {
3603 split = true; // second word is covered by full inits
3604 // Example: int a[] = { ... 42, foo() ... }
3605 }
3606
3607 // Here's a case where init0 is neither 0 nor -1:
3608 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
3609 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
3610 // In this case the tile is not split; it is (jlong)42.
3611 // The big tile is stored down, and then the foo() value is inserted.
3612 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
3613
3614 Node* ctl = old->in(MemNode::Control);
3615 Node* adr = make_raw_address(offset, phase);
3616 const TypePtr* atp = TypeRawPtr::BOTTOM;
3617
3618 // One or two coalesced stores to plop down.
3619 Node* st[2];
3620 intptr_t off[2];
3621 int nst = 0;
3622 if (!split) {
3623 ++new_long;
3624 off[nst] = offset;
3625 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3626 phase->longcon(con), T_LONG);
3627 } else {
3628 // Omit either if it is a zero.
3629 if (con0 != 0) {
3630 ++new_int;
3631 off[nst] = offset;
3632 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3633 phase->intcon(con0), T_INT);
3634 }
3635 if (con1 != 0) {
3636 ++new_int;
3637 offset += BytesPerInt;
3638 adr = make_raw_address(offset, phase);
3639 off[nst] = offset;
3640 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3641 phase->intcon(con1), T_INT);
3642 }
3643 }
3644
3645 // Insert second store first, then the first before the second.
3646 // Insert each one just before any overlapping non-constant stores.
3647 while (nst > 0) {
3648 Node* st1 = st[--nst];
3649 C->copy_node_notes_to(st1, old);
3650 st1 = phase->transform(st1);
3651 offset = off[nst];
3652 assert(offset >= header_size, "do not smash header");
3653 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
3654 guarantee(ins_idx != 0, "must re-insert constant store");
3655 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
3656 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
3657 set_req(--ins_idx, st1);
3658 else
3659 ins_req(ins_idx, st1);
3660 }
3661 }
3662
3663 if (PrintCompilation && WizardMode)
3664 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
3665 old_subword, old_long, new_int, new_long);
3666 if (C->log() != NULL)
3667 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
3668 old_subword, old_long, new_int, new_long);
3669
3670 // Clean up any remaining occurrences of zmem:
3671 remove_extra_zeroes();
3672 }
3673
3674 // Explore forward from in(start) to find the first fully initialized
3675 // word, and return its offset. Skip groups of subword stores which
3676 // together initialize full words. If in(start) is itself part of a
3677 // fully initialized word, return the offset of in(start). If there
3678 // are no following full-word stores, or if something is fishy, return
3679 // a negative value.
3680 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
3681 int int_map = 0;
3682 intptr_t int_map_off = 0;
3683 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
3684
3685 for (uint i = start, limit = req(); i < limit; i++) {
3686 Node* st = in(i);
3687
3688 intptr_t st_off = get_store_offset(st, phase);
3689 if (st_off < 0) break; // return conservative answer
3690
3691 int st_size = st->as_Store()->memory_size();
3692 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
3693 return st_off; // we found a complete word init
3694 }
3695
3696 // update the map:
3697
3698 intptr_t this_int_off = align_size_down(st_off, BytesPerInt);
3699 if (this_int_off != int_map_off) {
3700 // reset the map:
3701 int_map = 0;
3702 int_map_off = this_int_off;
3703 }
3704
3705 int subword_off = st_off - this_int_off;
3706 int_map |= right_n_bits(st_size) << subword_off;
3707 if ((int_map & FULL_MAP) == FULL_MAP) {
3708 return this_int_off; // we found a complete word init
3709 }
3710
3711 // Did this store hit or cross the word boundary?
3712 intptr_t next_int_off = align_size_down(st_off + st_size, BytesPerInt);
3713 if (next_int_off == this_int_off + BytesPerInt) {
3714 // We passed the current int, without fully initializing it.
3715 int_map_off = next_int_off;
3716 int_map >>= BytesPerInt;
3717 } else if (next_int_off > this_int_off + BytesPerInt) {
3718 // We passed the current and next int.
3719 return this_int_off + BytesPerInt;
3720 }
3721 }
3722
3723 return -1;
3724 }
3725
3726
3727 // Called when the associated AllocateNode is expanded into CFG.
3728 // At this point, we may perform additional optimizations.
3729 // Linearize the stores by ascending offset, to make memory
3730 // activity as coherent as possible.
3731 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
3732 intptr_t header_size,
3733 Node* size_in_bytes,
3734 PhaseGVN* phase) {
3735 assert(!is_complete(), "not already complete");
3736 assert(stores_are_sane(phase), "");
3737 assert(allocation() != NULL, "must be present");
3738
3739 remove_extra_zeroes();
3740
3741 if (ReduceFieldZeroing || ReduceBulkZeroing)
3742 // reduce instruction count for common initialization patterns
3743 coalesce_subword_stores(header_size, size_in_bytes, phase);
3744
3745 Node* zmem = zero_memory(); // initially zero memory state
3746 Node* inits = zmem; // accumulating a linearized chain of inits
3747 #ifdef ASSERT
3748 intptr_t first_offset = allocation()->minimum_header_size();
3749 intptr_t last_init_off = first_offset; // previous init offset
3750 intptr_t last_init_end = first_offset; // previous init offset+size
3751 intptr_t last_tile_end = first_offset; // previous tile offset+size
3752 #endif
3753 intptr_t zeroes_done = header_size;
3754
3755 bool do_zeroing = true; // we might give up if inits are very sparse
3756 int big_init_gaps = 0; // how many large gaps have we seen?
3757
3758 if (ZeroTLAB) do_zeroing = false;
3759 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
3760
3761 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3762 Node* st = in(i);
3763 intptr_t st_off = get_store_offset(st, phase);
3764 if (st_off < 0)
3765 break; // unknown junk in the inits
3766 if (st->in(MemNode::Memory) != zmem)
3767 break; // complicated store chains somehow in list
3768
3769 int st_size = st->as_Store()->memory_size();
3770 intptr_t next_init_off = st_off + st_size;
3771
3772 if (do_zeroing && zeroes_done < next_init_off) {
3773 // See if this store needs a zero before it or under it.
3774 intptr_t zeroes_needed = st_off;
3775
3776 if (st_size < BytesPerInt) {
3777 // Look for subword stores which only partially initialize words.
3778 // If we find some, we must lay down some word-level zeroes first,
3779 // underneath the subword stores.
3780 //
3781 // Examples:
3782 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
3783 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
3784 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
3785 //
3786 // Note: coalesce_subword_stores may have already done this,
3787 // if it was prompted by constant non-zero subword initializers.
3788 // But this case can still arise with non-constant stores.
3789
3790 intptr_t next_full_store = find_next_fullword_store(i, phase);
3791
3792 // In the examples above:
3793 // in(i) p q r s x y z
3794 // st_off 12 13 14 15 12 13 14
3795 // st_size 1 1 1 1 1 1 1
3796 // next_full_s. 12 16 16 16 16 16 16
3797 // z's_done 12 16 16 16 12 16 12
3798 // z's_needed 12 16 16 16 16 16 16
3799 // zsize 0 0 0 0 4 0 4
3800 if (next_full_store < 0) {
3801 // Conservative tack: Zero to end of current word.
3802 zeroes_needed = align_size_up(zeroes_needed, BytesPerInt);
3803 } else {
3804 // Zero to beginning of next fully initialized word.
3805 // Or, don't zero at all, if we are already in that word.
3806 assert(next_full_store >= zeroes_needed, "must go forward");
3807 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
3808 zeroes_needed = next_full_store;
3809 }
3810 }
3811
3812 if (zeroes_needed > zeroes_done) {
3813 intptr_t zsize = zeroes_needed - zeroes_done;
3814 // Do some incremental zeroing on rawmem, in parallel with inits.
3815 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3816 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3817 zeroes_done, zeroes_needed,
3818 phase);
3819 zeroes_done = zeroes_needed;
3820 if (zsize > Matcher::init_array_short_size && ++big_init_gaps > 2)
3821 do_zeroing = false; // leave the hole, next time
3822 }
3823 }
3824
3825 // Collect the store and move on:
3826 st->set_req(MemNode::Memory, inits);
3827 inits = st; // put it on the linearized chain
3828 set_req(i, zmem); // unhook from previous position
3829
3830 if (zeroes_done == st_off)
3831 zeroes_done = next_init_off;
3832
3833 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
3834
3835 #ifdef ASSERT
3836 // Various order invariants. Weaker than stores_are_sane because
3837 // a large constant tile can be filled in by smaller non-constant stores.
3838 assert(st_off >= last_init_off, "inits do not reverse");
3839 last_init_off = st_off;
3840 const Type* val = NULL;
3841 if (st_size >= BytesPerInt &&
3842 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
3843 (int)val->basic_type() < (int)T_OBJECT) {
3844 assert(st_off >= last_tile_end, "tiles do not overlap");
3845 assert(st_off >= last_init_end, "tiles do not overwrite inits");
3846 last_tile_end = MAX2(last_tile_end, next_init_off);
3847 } else {
3848 intptr_t st_tile_end = align_size_up(next_init_off, BytesPerLong);
3849 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
3850 assert(st_off >= last_init_end, "inits do not overlap");
3851 last_init_end = next_init_off; // it's a non-tile
3852 }
3853 #endif //ASSERT
3854 }
3855
3856 remove_extra_zeroes(); // clear out all the zmems left over
3857 add_req(inits);
3858
3859 if (!ZeroTLAB) {
3860 // If anything remains to be zeroed, zero it all now.
3861 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3862 // if it is the last unused 4 bytes of an instance, forget about it
3863 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
3864 if (zeroes_done + BytesPerLong >= size_limit) {
3865 assert(allocation() != NULL, "");
3866 if (allocation()->Opcode() == Op_Allocate) {
3867 Node* klass_node = allocation()->in(AllocateNode::KlassNode);
3868 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass();
3869 if (zeroes_done == k->layout_helper())
3870 zeroes_done = size_limit;
3871 }
3872 }
3873 if (zeroes_done < size_limit) {
3874 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3875 zeroes_done, size_in_bytes, phase);
3876 }
3877 }
3878
3879 set_complete(phase);
3880 return rawmem;
3881 }
3882
3883
3884 #ifdef ASSERT
3885 bool InitializeNode::stores_are_sane(PhaseTransform* phase) {
3886 if (is_complete())
3887 return true; // stores could be anything at this point
3888 assert(allocation() != NULL, "must be present");
3889 intptr_t last_off = allocation()->minimum_header_size();
3890 for (uint i = InitializeNode::RawStores; i < req(); i++) {
3891 Node* st = in(i);
3892 intptr_t st_off = get_store_offset(st, phase);
3893 if (st_off < 0) continue; // ignore dead garbage
3894 if (last_off > st_off) {
3895 tty->print_cr("*** bad store offset at %d: %d > %d", i, last_off, st_off);
3896 this->dump(2);
3897 assert(false, "ascending store offsets");
3898 return false;
3899 }
3900 last_off = st_off + st->as_Store()->memory_size();
3901 }
3902 return true;
3903 }
3904 #endif //ASSERT
3905
3906
3907
3908
3909 //============================MergeMemNode=====================================
3910 //
3911 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
3912 // contributing store or call operations. Each contributor provides the memory
3913 // state for a particular "alias type" (see Compile::alias_type). For example,
3914 // if a MergeMem has an input X for alias category #6, then any memory reference
3915 // to alias category #6 may use X as its memory state input, as an exact equivalent
3916 // to using the MergeMem as a whole.
3917 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
3918 //
3919 // (Here, the <N> notation gives the index of the relevant adr_type.)
3920 //
3921 // In one special case (and more cases in the future), alias categories overlap.
3922 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
3923 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
3924 // it is exactly equivalent to that state W:
3925 // MergeMem(<Bot>: W) <==> W
3926 //
3927 // Usually, the merge has more than one input. In that case, where inputs
3928 // overlap (i.e., one is Bot), the narrower alias type determines the memory
3929 // state for that type, and the wider alias type (Bot) fills in everywhere else:
3930 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
3931 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
3932 //
3933 // A merge can take a "wide" memory state as one of its narrow inputs.
3934 // This simply means that the merge observes out only the relevant parts of
3935 // the wide input. That is, wide memory states arriving at narrow merge inputs
3936 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
3937 //
3938 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
3939 // and that memory slices "leak through":
3940 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
3941 //
3942 // But, in such a cascade, repeated memory slices can "block the leak":
3943 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
3944 //
3945 // In the last example, Y is not part of the combined memory state of the
3946 // outermost MergeMem. The system must, of course, prevent unschedulable
3947 // memory states from arising, so you can be sure that the state Y is somehow
3948 // a precursor to state Y'.
3949 //
3950 //
3951 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
3952 // of each MergeMemNode array are exactly the numerical alias indexes, including
3953 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
3954 // Compile::alias_type (and kin) produce and manage these indexes.
3955 //
3956 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
3957 // (Note that this provides quick access to the top node inside MergeMem methods,
3958 // without the need to reach out via TLS to Compile::current.)
3959 //
3960 // As a consequence of what was just described, a MergeMem that represents a full
3961 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
3962 // containing all alias categories.
3963 //
3964 // MergeMem nodes never (?) have control inputs, so in(0) is NULL.
3965 //
3966 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
3967 // a memory state for the alias type <N>, or else the top node, meaning that
3968 // there is no particular input for that alias type. Note that the length of
3969 // a MergeMem is variable, and may be extended at any time to accommodate new
3970 // memory states at larger alias indexes. When merges grow, they are of course
3971 // filled with "top" in the unused in() positions.
3972 //
3973 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
3974 // (Top was chosen because it works smoothly with passes like GCM.)
3975 //
3976 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
3977 // the type of random VM bits like TLS references.) Since it is always the
3978 // first non-Bot memory slice, some low-level loops use it to initialize an
3979 // index variable: for (i = AliasIdxRaw; i < req(); i++).
3980 //
3981 //
3982 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
3983 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
3984 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
3985 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
3986 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
3987 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
3988 //
3989 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
3990 // really that different from the other memory inputs. An abbreviation called
3991 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
3992 //
3993 //
3994 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
3995 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
3996 // that "emerges though" the base memory will be marked as excluding the alias types
3997 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
3998 //
3999 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
4000 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
4001 //
4002 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
4003 // (It is currently unimplemented.) As you can see, the resulting merge is
4004 // actually a disjoint union of memory states, rather than an overlay.
4005 //
4006
4007 //------------------------------MergeMemNode-----------------------------------
4008 Node* MergeMemNode::make_empty_memory() {
4009 Node* empty_memory = (Node*) Compile::current()->top();
4010 assert(empty_memory->is_top(), "correct sentinel identity");
4011 return empty_memory;
4012 }
4013
4014 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
4015 init_class_id(Class_MergeMem);
4016 // all inputs are nullified in Node::Node(int)
4017 // set_input(0, NULL); // no control input
4018
4019 // Initialize the edges uniformly to top, for starters.
4020 Node* empty_mem = make_empty_memory();
4021 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
4022 init_req(i,empty_mem);
4023 }
4024 assert(empty_memory() == empty_mem, "");
4025
4026 if( new_base != NULL && new_base->is_MergeMem() ) {
4027 MergeMemNode* mdef = new_base->as_MergeMem();
4028 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
4029 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
4030 mms.set_memory(mms.memory2());
4031 }
4032 assert(base_memory() == mdef->base_memory(), "");
4033 } else {
4034 set_base_memory(new_base);
4035 }
4036 }
4037
4038 // Make a new, untransformed MergeMem with the same base as 'mem'.
4039 // If mem is itself a MergeMem, populate the result with the same edges.
4040 MergeMemNode* MergeMemNode::make(Compile* C, Node* mem) {
4041 return new(C) MergeMemNode(mem);
4042 }
4043
4044 //------------------------------cmp--------------------------------------------
4045 uint MergeMemNode::hash() const { return NO_HASH; }
4046 uint MergeMemNode::cmp( const Node &n ) const {
4047 return (&n == this); // Always fail except on self
4048 }
4049
4050 //------------------------------Identity---------------------------------------
4051 Node* MergeMemNode::Identity(PhaseTransform *phase) {
4052 // Identity if this merge point does not record any interesting memory
4053 // disambiguations.
4054 Node* base_mem = base_memory();
4055 Node* empty_mem = empty_memory();
4056 if (base_mem != empty_mem) { // Memory path is not dead?
4057 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4058 Node* mem = in(i);
4059 if (mem != empty_mem && mem != base_mem) {
4060 return this; // Many memory splits; no change
4061 }
4062 }
4063 }
4064 return base_mem; // No memory splits; ID on the one true input
4065 }
4066
4067 //------------------------------Ideal------------------------------------------
4068 // This method is invoked recursively on chains of MergeMem nodes
4069 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4070 // Remove chain'd MergeMems
4071 //
4072 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
4073 // relative to the "in(Bot)". Since we are patching both at the same time,
4074 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
4075 // but rewrite each "in(i)" relative to the new "in(Bot)".
4076 Node *progress = NULL;
4077
4078
4079 Node* old_base = base_memory();
4080 Node* empty_mem = empty_memory();
4081 if (old_base == empty_mem)
4082 return NULL; // Dead memory path.
4083
4084 MergeMemNode* old_mbase;
4085 if (old_base != NULL && old_base->is_MergeMem())
4086 old_mbase = old_base->as_MergeMem();
4087 else
4088 old_mbase = NULL;
4089 Node* new_base = old_base;
4090
4091 // simplify stacked MergeMems in base memory
4092 if (old_mbase) new_base = old_mbase->base_memory();
4093
4094 // the base memory might contribute new slices beyond my req()
4095 if (old_mbase) grow_to_match(old_mbase);
4096
4097 // Look carefully at the base node if it is a phi.
4098 PhiNode* phi_base;
4099 if (new_base != NULL && new_base->is_Phi())
4100 phi_base = new_base->as_Phi();
4101 else
4102 phi_base = NULL;
4103
4104 Node* phi_reg = NULL;
4105 uint phi_len = (uint)-1;
4106 if (phi_base != NULL && !phi_base->is_copy()) {
4107 // do not examine phi if degraded to a copy
4108 phi_reg = phi_base->region();
4109 phi_len = phi_base->req();
4110 // see if the phi is unfinished
4111 for (uint i = 1; i < phi_len; i++) {
4112 if (phi_base->in(i) == NULL) {
4113 // incomplete phi; do not look at it yet!
4114 phi_reg = NULL;
4115 phi_len = (uint)-1;
4116 break;
4117 }
4118 }
4119 }
4120
4121 // Note: We do not call verify_sparse on entry, because inputs
4122 // can normalize to the base_memory via subsume_node or similar
4123 // mechanisms. This method repairs that damage.
4124
4125 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
4126
4127 // Look at each slice.
4128 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4129 Node* old_in = in(i);
4130 // calculate the old memory value
4131 Node* old_mem = old_in;
4132 if (old_mem == empty_mem) old_mem = old_base;
4133 assert(old_mem == memory_at(i), "");
4134
4135 // maybe update (reslice) the old memory value
4136
4137 // simplify stacked MergeMems
4138 Node* new_mem = old_mem;
4139 MergeMemNode* old_mmem;
4140 if (old_mem != NULL && old_mem->is_MergeMem())
4141 old_mmem = old_mem->as_MergeMem();
4142 else
4143 old_mmem = NULL;
4144 if (old_mmem == this) {
4145 // This can happen if loops break up and safepoints disappear.
4146 // A merge of BotPtr (default) with a RawPtr memory derived from a
4147 // safepoint can be rewritten to a merge of the same BotPtr with
4148 // the BotPtr phi coming into the loop. If that phi disappears
4149 // also, we can end up with a self-loop of the mergemem.
4150 // In general, if loops degenerate and memory effects disappear,
4151 // a mergemem can be left looking at itself. This simply means
4152 // that the mergemem's default should be used, since there is
4153 // no longer any apparent effect on this slice.
4154 // Note: If a memory slice is a MergeMem cycle, it is unreachable
4155 // from start. Update the input to TOP.
4156 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
4157 }
4158 else if (old_mmem != NULL) {
4159 new_mem = old_mmem->memory_at(i);
4160 }
4161 // else preceding memory was not a MergeMem
4162
4163 // replace equivalent phis (unfortunately, they do not GVN together)
4164 if (new_mem != NULL && new_mem != new_base &&
4165 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) {
4166 if (new_mem->is_Phi()) {
4167 PhiNode* phi_mem = new_mem->as_Phi();
4168 for (uint i = 1; i < phi_len; i++) {
4169 if (phi_base->in(i) != phi_mem->in(i)) {
4170 phi_mem = NULL;
4171 break;
4172 }
4173 }
4174 if (phi_mem != NULL) {
4175 // equivalent phi nodes; revert to the def
4176 new_mem = new_base;
4177 }
4178 }
4179 }
4180
4181 // maybe store down a new value
4182 Node* new_in = new_mem;
4183 if (new_in == new_base) new_in = empty_mem;
4184
4185 if (new_in != old_in) {
4186 // Warning: Do not combine this "if" with the previous "if"
4187 // A memory slice might have be be rewritten even if it is semantically
4188 // unchanged, if the base_memory value has changed.
4189 set_req(i, new_in);
4190 progress = this; // Report progress
4191 }
4192 }
4193
4194 if (new_base != old_base) {
4195 set_req(Compile::AliasIdxBot, new_base);
4196 // Don't use set_base_memory(new_base), because we need to update du.
4197 assert(base_memory() == new_base, "");
4198 progress = this;
4199 }
4200
4201 if( base_memory() == this ) {
4202 // a self cycle indicates this memory path is dead
4203 set_req(Compile::AliasIdxBot, empty_mem);
4204 }
4205
4206 // Resolve external cycles by calling Ideal on a MergeMem base_memory
4207 // Recursion must occur after the self cycle check above
4208 if( base_memory()->is_MergeMem() ) {
4209 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
4210 Node *m = phase->transform(new_mbase); // Rollup any cycles
4211 if( m != NULL && (m->is_top() ||
4212 m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem) ) {
4213 // propagate rollup of dead cycle to self
4214 set_req(Compile::AliasIdxBot, empty_mem);
4215 }
4216 }
4217
4218 if( base_memory() == empty_mem ) {
4219 progress = this;
4220 // Cut inputs during Parse phase only.
4221 // During Optimize phase a dead MergeMem node will be subsumed by Top.
4222 if( !can_reshape ) {
4223 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4224 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
4225 }
4226 }
4227 }
4228
4229 if( !progress && base_memory()->is_Phi() && can_reshape ) {
4230 // Check if PhiNode::Ideal's "Split phis through memory merges"
4231 // transform should be attempted. Look for this->phi->this cycle.
4232 uint merge_width = req();
4233 if (merge_width > Compile::AliasIdxRaw) {
4234 PhiNode* phi = base_memory()->as_Phi();
4235 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
4236 if (phi->in(i) == this) {
4237 phase->is_IterGVN()->_worklist.push(phi);
4238 break;
4239 }
4240 }
4241 }
4242 }
4243
4244 assert(progress || verify_sparse(), "please, no dups of base");
4245 return progress;
4246 }
4247
4248 //-------------------------set_base_memory-------------------------------------
4249 void MergeMemNode::set_base_memory(Node *new_base) {
4250 Node* empty_mem = empty_memory();
4251 set_req(Compile::AliasIdxBot, new_base);
4252 assert(memory_at(req()) == new_base, "must set default memory");
4253 // Clear out other occurrences of new_base:
4254 if (new_base != empty_mem) {
4255 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4256 if (in(i) == new_base) set_req(i, empty_mem);
4257 }
4258 }
4259 }
4260
4261 //------------------------------out_RegMask------------------------------------
4262 const RegMask &MergeMemNode::out_RegMask() const {
4263 return RegMask::Empty;
4264 }
4265
4266 //------------------------------dump_spec--------------------------------------
4267 #ifndef PRODUCT
4268 void MergeMemNode::dump_spec(outputStream *st) const {
4269 st->print(" {");
4270 Node* base_mem = base_memory();
4271 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
4272 Node* mem = memory_at(i);
4273 if (mem == base_mem) { st->print(" -"); continue; }
4274 st->print( " N%d:", mem->_idx );
4275 Compile::current()->get_adr_type(i)->dump_on(st);
4276 }
4277 st->print(" }");
4278 }
4279 #endif // !PRODUCT
4280
4281
4282 #ifdef ASSERT
4283 static bool might_be_same(Node* a, Node* b) {
4284 if (a == b) return true;
4285 if (!(a->is_Phi() || b->is_Phi())) return false;
4286 // phis shift around during optimization
4287 return true; // pretty stupid...
4288 }
4289
4290 // verify a narrow slice (either incoming or outgoing)
4291 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
4292 if (!VerifyAliases) return; // don't bother to verify unless requested
4293 if (is_error_reported()) return; // muzzle asserts when debugging an error
4294 if (Node::in_dump()) return; // muzzle asserts when printing
4295 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
4296 assert(n != NULL, "");
4297 // Elide intervening MergeMem's
4298 while (n->is_MergeMem()) {
4299 n = n->as_MergeMem()->memory_at(alias_idx);
4300 }
4301 Compile* C = Compile::current();
4302 const TypePtr* n_adr_type = n->adr_type();
4303 if (n == m->empty_memory()) {
4304 // Implicit copy of base_memory()
4305 } else if (n_adr_type != TypePtr::BOTTOM) {
4306 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type");
4307 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
4308 } else {
4309 // A few places like make_runtime_call "know" that VM calls are narrow,
4310 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
4311 bool expected_wide_mem = false;
4312 if (n == m->base_memory()) {
4313 expected_wide_mem = true;
4314 } else if (alias_idx == Compile::AliasIdxRaw ||
4315 n == m->memory_at(Compile::AliasIdxRaw)) {
4316 expected_wide_mem = true;
4317 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
4318 // memory can "leak through" calls on channels that
4319 // are write-once. Allow this also.
4320 expected_wide_mem = true;
4321 }
4322 assert(expected_wide_mem, "expected narrow slice replacement");
4323 }
4324 }
4325 #else // !ASSERT
4326 #define verify_memory_slice(m,i,n) (0) // PRODUCT version is no-op
4327 #endif
4328
4329
4330 //-----------------------------memory_at---------------------------------------
4331 Node* MergeMemNode::memory_at(uint alias_idx) const {
4332 assert(alias_idx >= Compile::AliasIdxRaw ||
4333 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0,
4334 "must avoid base_memory and AliasIdxTop");
4335
4336 // Otherwise, it is a narrow slice.
4337 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
4338 Compile *C = Compile::current();
4339 if (is_empty_memory(n)) {
4340 // the array is sparse; empty slots are the "top" node
4341 n = base_memory();
4342 assert(Node::in_dump()
4343 || n == NULL || n->bottom_type() == Type::TOP
4344 || n->adr_type() == NULL // address is TOP
4345 || n->adr_type() == TypePtr::BOTTOM
4346 || n->adr_type() == TypeRawPtr::BOTTOM
4347 || Compile::current()->AliasLevel() == 0,
4348 "must be a wide memory");
4349 // AliasLevel == 0 if we are organizing the memory states manually.
4350 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
4351 } else {
4352 // make sure the stored slice is sane
4353 #ifdef ASSERT
4354 if (is_error_reported() || Node::in_dump()) {
4355 } else if (might_be_same(n, base_memory())) {
4356 // Give it a pass: It is a mostly harmless repetition of the base.
4357 // This can arise normally from node subsumption during optimization.
4358 } else {
4359 verify_memory_slice(this, alias_idx, n);
4360 }
4361 #endif
4362 }
4363 return n;
4364 }
4365
4366 //---------------------------set_memory_at-------------------------------------
4367 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
4368 verify_memory_slice(this, alias_idx, n);
4369 Node* empty_mem = empty_memory();
4370 if (n == base_memory()) n = empty_mem; // collapse default
4371 uint need_req = alias_idx+1;
4372 if (req() < need_req) {
4373 if (n == empty_mem) return; // already the default, so do not grow me
4374 // grow the sparse array
4375 do {
4376 add_req(empty_mem);
4377 } while (req() < need_req);
4378 }
4379 set_req( alias_idx, n );
4380 }
4381
4382
4383
4384 //--------------------------iteration_setup------------------------------------
4385 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
4386 if (other != NULL) {
4387 grow_to_match(other);
4388 // invariant: the finite support of mm2 is within mm->req()
4389 #ifdef ASSERT
4390 for (uint i = req(); i < other->req(); i++) {
4391 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
4392 }
4393 #endif
4394 }
4395 // Replace spurious copies of base_memory by top.
4396 Node* base_mem = base_memory();
4397 if (base_mem != NULL && !base_mem->is_top()) {
4398 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
4399 if (in(i) == base_mem)
4400 set_req(i, empty_memory());
4401 }
4402 }
4403 }
4404
4405 //---------------------------grow_to_match-------------------------------------
4406 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
4407 Node* empty_mem = empty_memory();
4408 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
4409 // look for the finite support of the other memory
4410 for (uint i = other->req(); --i >= req(); ) {
4411 if (other->in(i) != empty_mem) {
4412 uint new_len = i+1;
4413 while (req() < new_len) add_req(empty_mem);
4414 break;
4415 }
4416 }
4417 }
4418
4419 //---------------------------verify_sparse-------------------------------------
4420 #ifndef PRODUCT
4421 bool MergeMemNode::verify_sparse() const {
4422 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
4423 Node* base_mem = base_memory();
4424 // The following can happen in degenerate cases, since empty==top.
4425 if (is_empty_memory(base_mem)) return true;
4426 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4427 assert(in(i) != NULL, "sane slice");
4428 if (in(i) == base_mem) return false; // should have been the sentinel value!
4429 }
4430 return true;
4431 }
4432
4433 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
4434 Node* n;
4435 n = mm->in(idx);
4436 if (mem == n) return true; // might be empty_memory()
4437 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
4438 if (mem == n) return true;
4439 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) {
4440 if (mem == n) return true;
4441 if (n == NULL) break;
4442 }
4443 return false;
4444 }
4445 #endif // !PRODUCT