1 /*
2 * Copyright 1997-2008 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
24
25 // Portions of code courtesy of Clifford Click
26
27 // Optimization - Graph Style
28
29 #include "incls/_precompiled.incl"
30 #include "incls/_memnode.cpp.incl"
31
32 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st);
33
34 //=============================================================================
35 uint MemNode::size_of() const { return sizeof(*this); }
36
37 const TypePtr *MemNode::adr_type() const {
38 Node* adr = in(Address);
39 const TypePtr* cross_check = NULL;
40 DEBUG_ONLY(cross_check = _adr_type);
41 return calculate_adr_type(adr->bottom_type(), cross_check);
42 }
43
44 #ifndef PRODUCT
45 void MemNode::dump_spec(outputStream *st) const {
46 if (in(Address) == NULL) return; // node is dead
47 #ifndef ASSERT
48 // fake the missing field
49 const TypePtr* _adr_type = NULL;
50 if (in(Address) != NULL)
51 _adr_type = in(Address)->bottom_type()->isa_ptr();
52 #endif
53 dump_adr_type(this, _adr_type, st);
54
55 Compile* C = Compile::current();
56 if( C->alias_type(_adr_type)->is_volatile() )
57 st->print(" Volatile!");
58 }
59
60 void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) {
61 st->print(" @");
62 if (adr_type == NULL) {
63 st->print("NULL");
64 } else {
65 adr_type->dump_on(st);
66 Compile* C = Compile::current();
67 Compile::AliasType* atp = NULL;
68 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type);
69 if (atp == NULL)
70 st->print(", idx=?\?;");
71 else if (atp->index() == Compile::AliasIdxBot)
72 st->print(", idx=Bot;");
73 else if (atp->index() == Compile::AliasIdxTop)
74 st->print(", idx=Top;");
75 else if (atp->index() == Compile::AliasIdxRaw)
76 st->print(", idx=Raw;");
77 else {
78 ciField* field = atp->field();
79 if (field) {
80 st->print(", name=");
81 field->print_name_on(st);
82 }
83 st->print(", idx=%d;", atp->index());
84 }
85 }
86 }
87
88 extern void print_alias_types();
89
90 #endif
91
92 Node *MemNode::optimize_simple_memory_chain(Node *mchain, const TypePtr *t_adr, PhaseGVN *phase) {
93 const TypeOopPtr *tinst = t_adr->isa_oopptr();
94 if (tinst == NULL || !tinst->is_known_instance_field())
95 return mchain; // don't try to optimize non-instance types
96 uint instance_id = tinst->instance_id();
97 Node *start_mem = phase->C->start()->proj_out(TypeFunc::Memory);
98 Node *prev = NULL;
99 Node *result = mchain;
100 while (prev != result) {
101 prev = result;
102 if (result == start_mem)
103 break; // hit one of our sentinals
104 // skip over a call which does not affect this memory slice
105 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {
106 Node *proj_in = result->in(0);
107 if (proj_in->is_Allocate() && proj_in->_idx == instance_id) {
108 break; // hit one of our sentinals
109 } else if (proj_in->is_Call()) {
110 CallNode *call = proj_in->as_Call();
111 if (!call->may_modify(t_adr, phase)) {
112 result = call->in(TypeFunc::Memory);
113 }
114 } else if (proj_in->is_Initialize()) {
115 AllocateNode* alloc = proj_in->as_Initialize()->allocation();
116 // Stop if this is the initialization for the object instance which
117 // which contains this memory slice, otherwise skip over it.
118 if (alloc != NULL && alloc->_idx != instance_id) {
119 result = proj_in->in(TypeFunc::Memory);
120 }
121 } else if (proj_in->is_MemBar()) {
122 result = proj_in->in(TypeFunc::Memory);
123 } else {
124 assert(false, "unexpected projection");
125 }
126 } else if (result->is_MergeMem()) {
127 result = step_through_mergemem(phase, result->as_MergeMem(), t_adr, NULL, tty);
128 }
129 }
130 return result;
131 }
132
133 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, PhaseGVN *phase) {
134 const TypeOopPtr *t_oop = t_adr->isa_oopptr();
135 bool is_instance = (t_oop != NULL) && t_oop->is_known_instance_field();
136 PhaseIterGVN *igvn = phase->is_IterGVN();
137 Node *result = mchain;
138 result = optimize_simple_memory_chain(result, t_adr, phase);
139 if (is_instance && igvn != NULL && result->is_Phi()) {
140 PhiNode *mphi = result->as_Phi();
141 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
142 const TypePtr *t = mphi->adr_type();
143 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
144 t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
145 t->is_oopptr()->cast_to_exactness(true)
146 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
147 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop) {
148 // clone the Phi with our address type
149 result = mphi->split_out_instance(t_adr, igvn);
150 } else {
151 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain");
152 }
153 }
154 return result;
155 }
156
157 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) {
158 uint alias_idx = phase->C->get_alias_index(tp);
159 Node *mem = mmem;
160 #ifdef ASSERT
161 {
162 // Check that current type is consistent with the alias index used during graph construction
163 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
164 bool consistent = adr_check == NULL || adr_check->empty() ||
165 phase->C->must_alias(adr_check, alias_idx );
166 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
167 if( !consistent && adr_check != NULL && !adr_check->empty() &&
168 tp->isa_aryptr() && tp->offset() == Type::OffsetBot &&
169 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot &&
170 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() ||
171 adr_check->offset() == oopDesc::klass_offset_in_bytes() ||
172 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) {
173 // don't assert if it is dead code.
174 consistent = true;
175 }
176 if( !consistent ) {
177 st->print("alias_idx==%d, adr_check==", alias_idx);
178 if( adr_check == NULL ) {
179 st->print("NULL");
180 } else {
181 adr_check->dump();
182 }
183 st->cr();
184 print_alias_types();
185 assert(consistent, "adr_check must match alias idx");
186 }
187 }
188 #endif
189 // TypeInstPtr::NOTNULL+any is an OOP with unknown offset - generally
190 // means an array I have not precisely typed yet. Do not do any
191 // alias stuff with it any time soon.
192 const TypeOopPtr *tinst = tp->isa_oopptr();
193 if( tp->base() != Type::AnyPtr &&
194 !(tinst &&
195 tinst->klass()->is_java_lang_Object() &&
196 tinst->offset() == Type::OffsetBot) ) {
197 // compress paths and change unreachable cycles to TOP
198 // If not, we can update the input infinitely along a MergeMem cycle
199 // Equivalent code in PhiNode::Ideal
200 Node* m = phase->transform(mmem);
201 // If tranformed to a MergeMem, get the desired slice
202 // Otherwise the returned node represents memory for every slice
203 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
204 // Update input if it is progress over what we have now
205 }
206 return mem;
207 }
208
209 //--------------------------Ideal_common---------------------------------------
210 // Look for degenerate control and memory inputs. Bypass MergeMem inputs.
211 // Unhook non-raw memories from complete (macro-expanded) initializations.
212 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
213 // If our control input is a dead region, kill all below the region
214 Node *ctl = in(MemNode::Control);
215 if (ctl && remove_dead_region(phase, can_reshape))
216 return this;
217 ctl = in(MemNode::Control);
218 // Don't bother trying to transform a dead node
219 if( ctl && ctl->is_top() ) return NodeSentinel;
220
221 // Ignore if memory is dead, or self-loop
222 Node *mem = in(MemNode::Memory);
223 if( phase->type( mem ) == Type::TOP ) return NodeSentinel; // caller will return NULL
224 assert( mem != this, "dead loop in MemNode::Ideal" );
225
226 Node *address = in(MemNode::Address);
227 const Type *t_adr = phase->type( address );
228 if( t_adr == Type::TOP ) return NodeSentinel; // caller will return NULL
229
230 PhaseIterGVN *igvn = phase->is_IterGVN();
231 if( can_reshape && igvn != NULL && igvn->_worklist.member(address) ) {
232 // The address's base and type may change when the address is processed.
233 // Delay this mem node transformation until the address is processed.
234 phase->is_IterGVN()->_worklist.push(this);
235 return NodeSentinel; // caller will return NULL
236 }
237
238 // Avoid independent memory operations
239 Node* old_mem = mem;
240
241 // The code which unhooks non-raw memories from complete (macro-expanded)
242 // initializations was removed. After macro-expansion all stores catched
243 // by Initialize node became raw stores and there is no information
244 // which memory slices they modify. So it is unsafe to move any memory
245 // operation above these stores. Also in most cases hooked non-raw memories
246 // were already unhooked by using information from detect_ptr_independence()
247 // and find_previous_store().
248
249 if (mem->is_MergeMem()) {
250 MergeMemNode* mmem = mem->as_MergeMem();
251 const TypePtr *tp = t_adr->is_ptr();
252
253 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
254 }
255
256 if (mem != old_mem) {
257 set_req(MemNode::Memory, mem);
258 if (phase->type( mem ) == Type::TOP) return NodeSentinel;
259 return this;
260 }
261
262 // let the subclass continue analyzing...
263 return NULL;
264 }
265
266 // Helper function for proving some simple control dominations.
267 // Attempt to prove that all control inputs of 'dom' dominate 'sub'.
268 // Already assumes that 'dom' is available at 'sub', and that 'sub'
269 // is not a constant (dominated by the method's StartNode).
270 // Used by MemNode::find_previous_store to prove that the
271 // control input of a memory operation predates (dominates)
272 // an allocation it wants to look past.
273 bool MemNode::all_controls_dominate(Node* dom, Node* sub) {
274 if (dom == NULL || dom->is_top() || sub == NULL || sub->is_top())
275 return false; // Conservative answer for dead code
276
277 // Check 'dom'. Skip Proj and CatchProj nodes.
278 dom = dom->find_exact_control(dom);
279 if (dom == NULL || dom->is_top())
280 return false; // Conservative answer for dead code
281
282 if (dom == sub) {
283 // For the case when, for example, 'sub' is Initialize and the original
284 // 'dom' is Proj node of the 'sub'.
285 return false;
286 }
287
288 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub)
289 return true;
290
291 // 'dom' dominates 'sub' if its control edge and control edges
292 // of all its inputs dominate or equal to sub's control edge.
293
294 // Currently 'sub' is either Allocate, Initialize or Start nodes.
295 // Or Region for the check in LoadNode::Ideal();
296 // 'sub' should have sub->in(0) != NULL.
297 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() ||
298 sub->is_Region(), "expecting only these nodes");
299
300 // Get control edge of 'sub'.
301 Node* orig_sub = sub;
302 sub = sub->find_exact_control(sub->in(0));
303 if (sub == NULL || sub->is_top())
304 return false; // Conservative answer for dead code
305
306 assert(sub->is_CFG(), "expecting control");
307
308 if (sub == dom)
309 return true;
310
311 if (sub->is_Start() || sub->is_Root())
312 return false;
313
314 {
315 // Check all control edges of 'dom'.
316
317 ResourceMark rm;
318 Arena* arena = Thread::current()->resource_area();
319 Node_List nlist(arena);
320 Unique_Node_List dom_list(arena);
321
322 dom_list.push(dom);
323 bool only_dominating_controls = false;
324
325 for (uint next = 0; next < dom_list.size(); next++) {
326 Node* n = dom_list.at(next);
327 if (n == orig_sub)
328 return false; // One of dom's inputs dominated by sub.
329 if (!n->is_CFG() && n->pinned()) {
330 // Check only own control edge for pinned non-control nodes.
331 n = n->find_exact_control(n->in(0));
332 if (n == NULL || n->is_top())
333 return false; // Conservative answer for dead code
334 assert(n->is_CFG(), "expecting control");
335 dom_list.push(n);
336 } else if (n->is_Con() || n->is_Start() || n->is_Root()) {
337 only_dominating_controls = true;
338 } else if (n->is_CFG()) {
339 if (n->dominates(sub, nlist))
340 only_dominating_controls = true;
341 else
342 return false;
343 } else {
344 // First, own control edge.
345 Node* m = n->find_exact_control(n->in(0));
346 if (m != NULL) {
347 if (m->is_top())
348 return false; // Conservative answer for dead code
349 dom_list.push(m);
350 }
351 // Now, the rest of edges.
352 uint cnt = n->req();
353 for (uint i = 1; i < cnt; i++) {
354 m = n->find_exact_control(n->in(i));
355 if (m == NULL || m->is_top())
356 continue;
357 dom_list.push(m);
358 }
359 }
360 }
361 return only_dominating_controls;
362 }
363 }
364
365 //---------------------detect_ptr_independence---------------------------------
366 // Used by MemNode::find_previous_store to prove that two base
367 // pointers are never equal.
368 // The pointers are accompanied by their associated allocations,
369 // if any, which have been previously discovered by the caller.
370 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
371 Node* p2, AllocateNode* a2,
372 PhaseTransform* phase) {
373 // Attempt to prove that these two pointers cannot be aliased.
374 // They may both manifestly be allocations, and they should differ.
375 // Or, if they are not both allocations, they can be distinct constants.
376 // Otherwise, one is an allocation and the other a pre-existing value.
377 if (a1 == NULL && a2 == NULL) { // neither an allocation
378 return (p1 != p2) && p1->is_Con() && p2->is_Con();
379 } else if (a1 != NULL && a2 != NULL) { // both allocations
380 return (a1 != a2);
381 } else if (a1 != NULL) { // one allocation a1
382 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.)
383 return all_controls_dominate(p2, a1);
384 } else { //(a2 != NULL) // one allocation a2
385 return all_controls_dominate(p1, a2);
386 }
387 return false;
388 }
389
390
391 // The logic for reordering loads and stores uses four steps:
392 // (a) Walk carefully past stores and initializations which we
393 // can prove are independent of this load.
394 // (b) Observe that the next memory state makes an exact match
395 // with self (load or store), and locate the relevant store.
396 // (c) Ensure that, if we were to wire self directly to the store,
397 // the optimizer would fold it up somehow.
398 // (d) Do the rewiring, and return, depending on some other part of
399 // the optimizer to fold up the load.
400 // This routine handles steps (a) and (b). Steps (c) and (d) are
401 // specific to loads and stores, so they are handled by the callers.
402 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.)
403 //
404 Node* MemNode::find_previous_store(PhaseTransform* phase) {
405 Node* ctrl = in(MemNode::Control);
406 Node* adr = in(MemNode::Address);
407 intptr_t offset = 0;
408 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
409 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase);
410
411 if (offset == Type::OffsetBot)
412 return NULL; // cannot unalias unless there are precise offsets
413
414 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr();
415
416 intptr_t size_in_bytes = memory_size();
417
418 Node* mem = in(MemNode::Memory); // start searching here...
419
420 int cnt = 50; // Cycle limiter
421 for (;;) { // While we can dance past unrelated stores...
422 if (--cnt < 0) break; // Caught in cycle or a complicated dance?
423
424 if (mem->is_Store()) {
425 Node* st_adr = mem->in(MemNode::Address);
426 intptr_t st_offset = 0;
427 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
428 if (st_base == NULL)
429 break; // inscrutable pointer
430 if (st_offset != offset && st_offset != Type::OffsetBot) {
431 const int MAX_STORE = BytesPerLong;
432 if (st_offset >= offset + size_in_bytes ||
433 st_offset <= offset - MAX_STORE ||
434 st_offset <= offset - mem->as_Store()->memory_size()) {
435 // Success: The offsets are provably independent.
436 // (You may ask, why not just test st_offset != offset and be done?
437 // The answer is that stores of different sizes can co-exist
438 // in the same sequence of RawMem effects. We sometimes initialize
439 // a whole 'tile' of array elements with a single jint or jlong.)
440 mem = mem->in(MemNode::Memory);
441 continue; // (a) advance through independent store memory
442 }
443 }
444 if (st_base != base &&
445 detect_ptr_independence(base, alloc,
446 st_base,
447 AllocateNode::Ideal_allocation(st_base, phase),
448 phase)) {
449 // Success: The bases are provably independent.
450 mem = mem->in(MemNode::Memory);
451 continue; // (a) advance through independent store memory
452 }
453
454 // (b) At this point, if the bases or offsets do not agree, we lose,
455 // since we have not managed to prove 'this' and 'mem' independent.
456 if (st_base == base && st_offset == offset) {
457 return mem; // let caller handle steps (c), (d)
458 }
459
460 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
461 InitializeNode* st_init = mem->in(0)->as_Initialize();
462 AllocateNode* st_alloc = st_init->allocation();
463 if (st_alloc == NULL)
464 break; // something degenerated
465 bool known_identical = false;
466 bool known_independent = false;
467 if (alloc == st_alloc)
468 known_identical = true;
469 else if (alloc != NULL)
470 known_independent = true;
471 else if (all_controls_dominate(this, st_alloc))
472 known_independent = true;
473
474 if (known_independent) {
475 // The bases are provably independent: Either they are
476 // manifestly distinct allocations, or else the control
477 // of this load dominates the store's allocation.
478 int alias_idx = phase->C->get_alias_index(adr_type());
479 if (alias_idx == Compile::AliasIdxRaw) {
480 mem = st_alloc->in(TypeFunc::Memory);
481 } else {
482 mem = st_init->memory(alias_idx);
483 }
484 continue; // (a) advance through independent store memory
485 }
486
487 // (b) at this point, if we are not looking at a store initializing
488 // the same allocation we are loading from, we lose.
489 if (known_identical) {
490 // From caller, can_see_stored_value will consult find_captured_store.
491 return mem; // let caller handle steps (c), (d)
492 }
493
494 } else if (addr_t != NULL && addr_t->is_known_instance_field()) {
495 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
496 if (mem->is_Proj() && mem->in(0)->is_Call()) {
497 CallNode *call = mem->in(0)->as_Call();
498 if (!call->may_modify(addr_t, phase)) {
499 mem = call->in(TypeFunc::Memory);
500 continue; // (a) advance through independent call memory
501 }
502 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) {
503 mem = mem->in(0)->in(TypeFunc::Memory);
504 continue; // (a) advance through independent MemBar memory
505 } else if (mem->is_MergeMem()) {
506 int alias_idx = phase->C->get_alias_index(adr_type());
507 mem = mem->as_MergeMem()->memory_at(alias_idx);
508 continue; // (a) advance through independent MergeMem memory
509 }
510 }
511
512 // Unless there is an explicit 'continue', we must bail out here,
513 // because 'mem' is an inscrutable memory state (e.g., a call).
514 break;
515 }
516
517 return NULL; // bail out
518 }
519
520 //----------------------calculate_adr_type-------------------------------------
521 // Helper function. Notices when the given type of address hits top or bottom.
522 // Also, asserts a cross-check of the type against the expected address type.
523 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
524 if (t == Type::TOP) return NULL; // does not touch memory any more?
525 #ifdef PRODUCT
526 cross_check = NULL;
527 #else
528 if (!VerifyAliases || is_error_reported() || Node::in_dump()) cross_check = NULL;
529 #endif
530 const TypePtr* tp = t->isa_ptr();
531 if (tp == NULL) {
532 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
533 return TypePtr::BOTTOM; // touches lots of memory
534 } else {
535 #ifdef ASSERT
536 // %%%% [phh] We don't check the alias index if cross_check is
537 // TypeRawPtr::BOTTOM. Needs to be investigated.
538 if (cross_check != NULL &&
539 cross_check != TypePtr::BOTTOM &&
540 cross_check != TypeRawPtr::BOTTOM) {
541 // Recheck the alias index, to see if it has changed (due to a bug).
542 Compile* C = Compile::current();
543 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
544 "must stay in the original alias category");
545 // The type of the address must be contained in the adr_type,
546 // disregarding "null"-ness.
547 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
548 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
549 assert(cross_check->meet(tp_notnull) == cross_check,
550 "real address must not escape from expected memory type");
551 }
552 #endif
553 return tp;
554 }
555 }
556
557 //------------------------adr_phi_is_loop_invariant----------------------------
558 // A helper function for Ideal_DU_postCCP to check if a Phi in a counted
559 // loop is loop invariant. Make a quick traversal of Phi and associated
560 // CastPP nodes, looking to see if they are a closed group within the loop.
561 bool MemNode::adr_phi_is_loop_invariant(Node* adr_phi, Node* cast) {
562 // The idea is that the phi-nest must boil down to only CastPP nodes
563 // with the same data. This implies that any path into the loop already
564 // includes such a CastPP, and so the original cast, whatever its input,
565 // must be covered by an equivalent cast, with an earlier control input.
566 ResourceMark rm;
567
568 // The loop entry input of the phi should be the unique dominating
569 // node for every Phi/CastPP in the loop.
570 Unique_Node_List closure;
571 closure.push(adr_phi->in(LoopNode::EntryControl));
572
573 // Add the phi node and the cast to the worklist.
574 Unique_Node_List worklist;
575 worklist.push(adr_phi);
576 if( cast != NULL ){
577 if( !cast->is_ConstraintCast() ) return false;
578 worklist.push(cast);
579 }
580
581 // Begin recursive walk of phi nodes.
582 while( worklist.size() ){
583 // Take a node off the worklist
584 Node *n = worklist.pop();
585 if( !closure.member(n) ){
586 // Add it to the closure.
587 closure.push(n);
588 // Make a sanity check to ensure we don't waste too much time here.
589 if( closure.size() > 20) return false;
590 // This node is OK if:
591 // - it is a cast of an identical value
592 // - or it is a phi node (then we add its inputs to the worklist)
593 // Otherwise, the node is not OK, and we presume the cast is not invariant
594 if( n->is_ConstraintCast() ){
595 worklist.push(n->in(1));
596 } else if( n->is_Phi() ) {
597 for( uint i = 1; i < n->req(); i++ ) {
598 worklist.push(n->in(i));
599 }
600 } else {
601 return false;
602 }
603 }
604 }
605
606 // Quit when the worklist is empty, and we've found no offending nodes.
607 return true;
608 }
609
610 //------------------------------Ideal_DU_postCCP-------------------------------
611 // Find any cast-away of null-ness and keep its control. Null cast-aways are
612 // going away in this pass and we need to make this memory op depend on the
613 // gating null check.
614 Node *MemNode::Ideal_DU_postCCP( PhaseCCP *ccp ) {
615 return Ideal_common_DU_postCCP(ccp, this, in(MemNode::Address));
616 }
617
618 // I tried to leave the CastPP's in. This makes the graph more accurate in
619 // some sense; we get to keep around the knowledge that an oop is not-null
620 // after some test. Alas, the CastPP's interfere with GVN (some values are
621 // the regular oop, some are the CastPP of the oop, all merge at Phi's which
622 // cannot collapse, etc). This cost us 10% on SpecJVM, even when I removed
623 // some of the more trivial cases in the optimizer. Removing more useless
624 // Phi's started allowing Loads to illegally float above null checks. I gave
625 // up on this approach. CNC 10/20/2000
626 // This static method may be called not from MemNode (EncodePNode calls it).
627 // Only the control edge of the node 'n' might be updated.
628 Node *MemNode::Ideal_common_DU_postCCP( PhaseCCP *ccp, Node* n, Node* adr ) {
629 Node *skipped_cast = NULL;
630 // Need a null check? Regular static accesses do not because they are
631 // from constant addresses. Array ops are gated by the range check (which
632 // always includes a NULL check). Just check field ops.
633 if( n->in(MemNode::Control) == NULL ) {
634 // Scan upwards for the highest location we can place this memory op.
635 while( true ) {
636 switch( adr->Opcode() ) {
637
638 case Op_AddP: // No change to NULL-ness, so peek thru AddP's
639 adr = adr->in(AddPNode::Base);
640 continue;
641
642 case Op_DecodeN: // No change to NULL-ness, so peek thru
643 adr = adr->in(1);
644 continue;
645
646 case Op_CastPP:
647 // If the CastPP is useless, just peek on through it.
648 if( ccp->type(adr) == ccp->type(adr->in(1)) ) {
649 // Remember the cast that we've peeked though. If we peek
650 // through more than one, then we end up remembering the highest
651 // one, that is, if in a loop, the one closest to the top.
652 skipped_cast = adr;
653 adr = adr->in(1);
654 continue;
655 }
656 // CastPP is going away in this pass! We need this memory op to be
657 // control-dependent on the test that is guarding the CastPP.
658 ccp->hash_delete(n);
659 n->set_req(MemNode::Control, adr->in(0));
660 ccp->hash_insert(n);
661 return n;
662
663 case Op_Phi:
664 // Attempt to float above a Phi to some dominating point.
665 if (adr->in(0) != NULL && adr->in(0)->is_CountedLoop()) {
666 // If we've already peeked through a Cast (which could have set the
667 // control), we can't float above a Phi, because the skipped Cast
668 // may not be loop invariant.
669 if (adr_phi_is_loop_invariant(adr, skipped_cast)) {
670 adr = adr->in(1);
671 continue;
672 }
673 }
674
675 // Intentional fallthrough!
676
677 // No obvious dominating point. The mem op is pinned below the Phi
678 // by the Phi itself. If the Phi goes away (no true value is merged)
679 // then the mem op can float, but not indefinitely. It must be pinned
680 // behind the controls leading to the Phi.
681 case Op_CheckCastPP:
682 // These usually stick around to change address type, however a
683 // useless one can be elided and we still need to pick up a control edge
684 if (adr->in(0) == NULL) {
685 // This CheckCastPP node has NO control and is likely useless. But we
686 // need check further up the ancestor chain for a control input to keep
687 // the node in place. 4959717.
688 skipped_cast = adr;
689 adr = adr->in(1);
690 continue;
691 }
692 ccp->hash_delete(n);
693 n->set_req(MemNode::Control, adr->in(0));
694 ccp->hash_insert(n);
695 return n;
696
697 // List of "safe" opcodes; those that implicitly block the memory
698 // op below any null check.
699 case Op_CastX2P: // no null checks on native pointers
700 case Op_Parm: // 'this' pointer is not null
701 case Op_LoadP: // Loading from within a klass
702 case Op_LoadN: // Loading from within a klass
703 case Op_LoadKlass: // Loading from within a klass
704 case Op_LoadNKlass: // Loading from within a klass
705 case Op_ConP: // Loading from a klass
706 case Op_ConN: // Loading from a klass
707 case Op_CreateEx: // Sucking up the guts of an exception oop
708 case Op_Con: // Reading from TLS
709 case Op_CMoveP: // CMoveP is pinned
710 case Op_CMoveN: // CMoveN is pinned
711 break; // No progress
712
713 case Op_Proj: // Direct call to an allocation routine
714 case Op_SCMemProj: // Memory state from store conditional ops
715 #ifdef ASSERT
716 {
717 assert(adr->as_Proj()->_con == TypeFunc::Parms, "must be return value");
718 const Node* call = adr->in(0);
719 if (call->is_CallJava()) {
720 const CallJavaNode* call_java = call->as_CallJava();
721 const TypeTuple *r = call_java->tf()->range();
722 assert(r->cnt() > TypeFunc::Parms, "must return value");
723 const Type* ret_type = r->field_at(TypeFunc::Parms);
724 assert(ret_type && ret_type->isa_ptr(), "must return pointer");
725 // We further presume that this is one of
726 // new_instance_Java, new_array_Java, or
727 // the like, but do not assert for this.
728 } else if (call->is_Allocate()) {
729 // similar case to new_instance_Java, etc.
730 } else if (!call->is_CallLeaf()) {
731 // Projections from fetch_oop (OSR) are allowed as well.
732 ShouldNotReachHere();
733 }
734 }
735 #endif
736 break;
737 default:
738 ShouldNotReachHere();
739 }
740 break;
741 }
742 }
743
744 return NULL; // No progress
745 }
746
747
748 //=============================================================================
749 uint LoadNode::size_of() const { return sizeof(*this); }
750 uint LoadNode::cmp( const Node &n ) const
751 { return !Type::cmp( _type, ((LoadNode&)n)._type ); }
752 const Type *LoadNode::bottom_type() const { return _type; }
753 uint LoadNode::ideal_reg() const {
754 return Matcher::base2reg[_type->base()];
755 }
756
757 #ifndef PRODUCT
758 void LoadNode::dump_spec(outputStream *st) const {
759 MemNode::dump_spec(st);
760 if( !Verbose && !WizardMode ) {
761 // standard dump does this in Verbose and WizardMode
762 st->print(" #"); _type->dump_on(st);
763 }
764 }
765 #endif
766
767
768 //----------------------------LoadNode::make-----------------------------------
769 // Polymorphic factory method:
770 Node *LoadNode::make( PhaseGVN& gvn, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt ) {
771 Compile* C = gvn.C;
772
773 // sanity check the alias category against the created node type
774 assert(!(adr_type->isa_oopptr() &&
775 adr_type->offset() == oopDesc::klass_offset_in_bytes()),
776 "use LoadKlassNode instead");
777 assert(!(adr_type->isa_aryptr() &&
778 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
779 "use LoadRangeNode instead");
780 switch (bt) {
781 case T_BOOLEAN:
782 case T_BYTE: return new (C, 3) LoadBNode (ctl, mem, adr, adr_type, rt->is_int() );
783 case T_INT: return new (C, 3) LoadINode (ctl, mem, adr, adr_type, rt->is_int() );
784 case T_CHAR: return new (C, 3) LoadUSNode(ctl, mem, adr, adr_type, rt->is_int() );
785 case T_SHORT: return new (C, 3) LoadSNode (ctl, mem, adr, adr_type, rt->is_int() );
786 case T_LONG: return new (C, 3) LoadLNode (ctl, mem, adr, adr_type, rt->is_long() );
787 case T_FLOAT: return new (C, 3) LoadFNode (ctl, mem, adr, adr_type, rt );
788 case T_DOUBLE: return new (C, 3) LoadDNode (ctl, mem, adr, adr_type, rt );
789 case T_ADDRESS: return new (C, 3) LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr() );
790 case T_OBJECT:
791 #ifdef _LP64
792 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
793 Node* load = gvn.transform(new (C, 3) LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop()));
794 return new (C, 2) DecodeNNode(load, load->bottom_type()->make_ptr());
795 } else
796 #endif
797 {
798 assert(!adr->bottom_type()->is_ptr_to_narrowoop(), "should have got back a narrow oop");
799 return new (C, 3) LoadPNode(ctl, mem, adr, adr_type, rt->is_oopptr());
800 }
801 }
802 ShouldNotReachHere();
803 return (LoadNode*)NULL;
804 }
805
806 LoadLNode* LoadLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt) {
807 bool require_atomic = true;
808 return new (C, 3) LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), require_atomic);
809 }
810
811
812
813
814 //------------------------------hash-------------------------------------------
815 uint LoadNode::hash() const {
816 // unroll addition of interesting fields
817 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
818 }
819
820 //---------------------------can_see_stored_value------------------------------
821 // This routine exists to make sure this set of tests is done the same
822 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
823 // will change the graph shape in a way which makes memory alive twice at the
824 // same time (uses the Oracle model of aliasing), then some
825 // LoadXNode::Identity will fold things back to the equivalence-class model
826 // of aliasing.
827 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const {
828 Node* ld_adr = in(MemNode::Address);
829
830 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
831 Compile::AliasType* atp = tp != NULL ? phase->C->alias_type(tp) : NULL;
832 if (EliminateAutoBox && atp != NULL && atp->index() >= Compile::AliasIdxRaw &&
833 atp->field() != NULL && !atp->field()->is_volatile()) {
834 uint alias_idx = atp->index();
835 bool final = atp->field()->is_final();
836 Node* result = NULL;
837 Node* current = st;
838 // Skip through chains of MemBarNodes checking the MergeMems for
839 // new states for the slice of this load. Stop once any other
840 // kind of node is encountered. Loads from final memory can skip
841 // through any kind of MemBar but normal loads shouldn't skip
842 // through MemBarAcquire since the could allow them to move out of
843 // a synchronized region.
844 while (current->is_Proj()) {
845 int opc = current->in(0)->Opcode();
846 if ((final && opc == Op_MemBarAcquire) ||
847 opc == Op_MemBarRelease || opc == Op_MemBarCPUOrder) {
848 Node* mem = current->in(0)->in(TypeFunc::Memory);
849 if (mem->is_MergeMem()) {
850 MergeMemNode* merge = mem->as_MergeMem();
851 Node* new_st = merge->memory_at(alias_idx);
852 if (new_st == merge->base_memory()) {
853 // Keep searching
854 current = merge->base_memory();
855 continue;
856 }
857 // Save the new memory state for the slice and fall through
858 // to exit.
859 result = new_st;
860 }
861 }
862 break;
863 }
864 if (result != NULL) {
865 st = result;
866 }
867 }
868
869
870 // Loop around twice in the case Load -> Initialize -> Store.
871 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
872 for (int trip = 0; trip <= 1; trip++) {
873
874 if (st->is_Store()) {
875 Node* st_adr = st->in(MemNode::Address);
876 if (!phase->eqv(st_adr, ld_adr)) {
877 // Try harder before giving up... Match raw and non-raw pointers.
878 intptr_t st_off = 0;
879 AllocateNode* alloc = AllocateNode::Ideal_allocation(st_adr, phase, st_off);
880 if (alloc == NULL) return NULL;
881 intptr_t ld_off = 0;
882 AllocateNode* allo2 = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
883 if (alloc != allo2) return NULL;
884 if (ld_off != st_off) return NULL;
885 // At this point we have proven something like this setup:
886 // A = Allocate(...)
887 // L = LoadQ(, AddP(CastPP(, A.Parm),, #Off))
888 // S = StoreQ(, AddP(, A.Parm , #Off), V)
889 // (Actually, we haven't yet proven the Q's are the same.)
890 // In other words, we are loading from a casted version of
891 // the same pointer-and-offset that we stored to.
892 // Thus, we are able to replace L by V.
893 }
894 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
895 if (store_Opcode() != st->Opcode())
896 return NULL;
897 return st->in(MemNode::ValueIn);
898 }
899
900 intptr_t offset = 0; // scratch
901
902 // A load from a freshly-created object always returns zero.
903 // (This can happen after LoadNode::Ideal resets the load's memory input
904 // to find_captured_store, which returned InitializeNode::zero_memory.)
905 if (st->is_Proj() && st->in(0)->is_Allocate() &&
906 st->in(0) == AllocateNode::Ideal_allocation(ld_adr, phase, offset) &&
907 offset >= st->in(0)->as_Allocate()->minimum_header_size()) {
908 // return a zero value for the load's basic type
909 // (This is one of the few places where a generic PhaseTransform
910 // can create new nodes. Think of it as lazily manifesting
911 // virtually pre-existing constants.)
912 return phase->zerocon(memory_type());
913 }
914
915 // A load from an initialization barrier can match a captured store.
916 if (st->is_Proj() && st->in(0)->is_Initialize()) {
917 InitializeNode* init = st->in(0)->as_Initialize();
918 AllocateNode* alloc = init->allocation();
919 if (alloc != NULL &&
920 alloc == AllocateNode::Ideal_allocation(ld_adr, phase, offset)) {
921 // examine a captured store value
922 st = init->find_captured_store(offset, memory_size(), phase);
923 if (st != NULL)
924 continue; // take one more trip around
925 }
926 }
927
928 break;
929 }
930
931 return NULL;
932 }
933
934 //----------------------is_instance_field_load_with_local_phi------------------
935 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
936 if( in(MemNode::Memory)->is_Phi() && in(MemNode::Memory)->in(0) == ctrl &&
937 in(MemNode::Address)->is_AddP() ) {
938 const TypeOopPtr* t_oop = in(MemNode::Address)->bottom_type()->isa_oopptr();
939 // Only instances.
940 if( t_oop != NULL && t_oop->is_known_instance_field() &&
941 t_oop->offset() != Type::OffsetBot &&
942 t_oop->offset() != Type::OffsetTop) {
943 return true;
944 }
945 }
946 return false;
947 }
948
949 //------------------------------Identity---------------------------------------
950 // Loads are identity if previous store is to same address
951 Node *LoadNode::Identity( PhaseTransform *phase ) {
952 // If the previous store-maker is the right kind of Store, and the store is
953 // to the same address, then we are equal to the value stored.
954 Node* mem = in(MemNode::Memory);
955 Node* value = can_see_stored_value(mem, phase);
956 if( value ) {
957 // byte, short & char stores truncate naturally.
958 // A load has to load the truncated value which requires
959 // some sort of masking operation and that requires an
960 // Ideal call instead of an Identity call.
961 if (memory_size() < BytesPerInt) {
962 // If the input to the store does not fit with the load's result type,
963 // it must be truncated via an Ideal call.
964 if (!phase->type(value)->higher_equal(phase->type(this)))
965 return this;
966 }
967 // (This works even when value is a Con, but LoadNode::Value
968 // usually runs first, producing the singleton type of the Con.)
969 return value;
970 }
971
972 // Search for an existing data phi which was generated before for the same
973 // instance's field to avoid infinite genertion of phis in a loop.
974 Node *region = mem->in(0);
975 if (is_instance_field_load_with_local_phi(region)) {
976 const TypePtr *addr_t = in(MemNode::Address)->bottom_type()->isa_ptr();
977 int this_index = phase->C->get_alias_index(addr_t);
978 int this_offset = addr_t->offset();
979 int this_id = addr_t->is_oopptr()->instance_id();
980 const Type* this_type = bottom_type();
981 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
982 Node* phi = region->fast_out(i);
983 if (phi->is_Phi() && phi != mem &&
984 phi->as_Phi()->is_same_inst_field(this_type, this_id, this_index, this_offset)) {
985 return phi;
986 }
987 }
988 }
989
990 return this;
991 }
992
993
994 // Returns true if the AliasType refers to the field that holds the
995 // cached box array. Currently only handles the IntegerCache case.
996 static bool is_autobox_cache(Compile::AliasType* atp) {
997 if (atp != NULL && atp->field() != NULL) {
998 ciField* field = atp->field();
999 ciSymbol* klass = field->holder()->name();
1000 if (field->name() == ciSymbol::cache_field_name() &&
1001 field->holder()->uses_default_loader() &&
1002 klass == ciSymbol::java_lang_Integer_IntegerCache()) {
1003 return true;
1004 }
1005 }
1006 return false;
1007 }
1008
1009 // Fetch the base value in the autobox array
1010 static bool fetch_autobox_base(Compile::AliasType* atp, int& cache_offset) {
1011 if (atp != NULL && atp->field() != NULL) {
1012 ciField* field = atp->field();
1013 ciSymbol* klass = field->holder()->name();
1014 if (field->name() == ciSymbol::cache_field_name() &&
1015 field->holder()->uses_default_loader() &&
1016 klass == ciSymbol::java_lang_Integer_IntegerCache()) {
1017 assert(field->is_constant(), "what?");
1018 ciObjArray* array = field->constant_value().as_object()->as_obj_array();
1019 // Fetch the box object at the base of the array and get its value
1020 ciInstance* box = array->obj_at(0)->as_instance();
1021 ciInstanceKlass* ik = box->klass()->as_instance_klass();
1022 if (ik->nof_nonstatic_fields() == 1) {
1023 // This should be true nonstatic_field_at requires calling
1024 // nof_nonstatic_fields so check it anyway
1025 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1026 cache_offset = c.as_int();
1027 }
1028 return true;
1029 }
1030 }
1031 return false;
1032 }
1033
1034 // Returns true if the AliasType refers to the value field of an
1035 // autobox object. Currently only handles Integer.
1036 static bool is_autobox_object(Compile::AliasType* atp) {
1037 if (atp != NULL && atp->field() != NULL) {
1038 ciField* field = atp->field();
1039 ciSymbol* klass = field->holder()->name();
1040 if (field->name() == ciSymbol::value_name() &&
1041 field->holder()->uses_default_loader() &&
1042 klass == ciSymbol::java_lang_Integer()) {
1043 return true;
1044 }
1045 }
1046 return false;
1047 }
1048
1049
1050 // We're loading from an object which has autobox behaviour.
1051 // If this object is result of a valueOf call we'll have a phi
1052 // merging a newly allocated object and a load from the cache.
1053 // We want to replace this load with the original incoming
1054 // argument to the valueOf call.
1055 Node* LoadNode::eliminate_autobox(PhaseGVN* phase) {
1056 Node* base = in(Address)->in(AddPNode::Base);
1057 if (base->is_Phi() && base->req() == 3) {
1058 AllocateNode* allocation = NULL;
1059 int allocation_index = -1;
1060 int load_index = -1;
1061 for (uint i = 1; i < base->req(); i++) {
1062 allocation = AllocateNode::Ideal_allocation(base->in(i), phase);
1063 if (allocation != NULL) {
1064 allocation_index = i;
1065 load_index = 3 - allocation_index;
1066 break;
1067 }
1068 }
1069 LoadNode* load = NULL;
1070 if (allocation != NULL && base->in(load_index)->is_Load()) {
1071 load = base->in(load_index)->as_Load();
1072 }
1073 if (load != NULL && in(Memory)->is_Phi() && in(Memory)->in(0) == base->in(0)) {
1074 // Push the loads from the phi that comes from valueOf up
1075 // through it to allow elimination of the loads and the recovery
1076 // of the original value.
1077 Node* mem_phi = in(Memory);
1078 Node* offset = in(Address)->in(AddPNode::Offset);
1079 Node* region = base->in(0);
1080
1081 Node* in1 = clone();
1082 Node* in1_addr = in1->in(Address)->clone();
1083 in1_addr->set_req(AddPNode::Base, base->in(allocation_index));
1084 in1_addr->set_req(AddPNode::Address, base->in(allocation_index));
1085 in1_addr->set_req(AddPNode::Offset, offset);
1086 in1->set_req(0, region->in(allocation_index));
1087 in1->set_req(Address, in1_addr);
1088 in1->set_req(Memory, mem_phi->in(allocation_index));
1089
1090 Node* in2 = clone();
1091 Node* in2_addr = in2->in(Address)->clone();
1092 in2_addr->set_req(AddPNode::Base, base->in(load_index));
1093 in2_addr->set_req(AddPNode::Address, base->in(load_index));
1094 in2_addr->set_req(AddPNode::Offset, offset);
1095 in2->set_req(0, region->in(load_index));
1096 in2->set_req(Address, in2_addr);
1097 in2->set_req(Memory, mem_phi->in(load_index));
1098
1099 in1_addr = phase->transform(in1_addr);
1100 in1 = phase->transform(in1);
1101 in2_addr = phase->transform(in2_addr);
1102 in2 = phase->transform(in2);
1103
1104 PhiNode* result = PhiNode::make_blank(region, this);
1105 result->set_req(allocation_index, in1);
1106 result->set_req(load_index, in2);
1107 return result;
1108 }
1109 } else if (base->is_Load()) {
1110 // Eliminate the load of Integer.value for integers from the cache
1111 // array by deriving the value from the index into the array.
1112 // Capture the offset of the load and then reverse the computation.
1113 Node* load_base = base->in(Address)->in(AddPNode::Base);
1114 if (load_base != NULL) {
1115 Compile::AliasType* atp = phase->C->alias_type(load_base->adr_type());
1116 intptr_t cache_offset;
1117 int shift = -1;
1118 Node* cache = NULL;
1119 if (is_autobox_cache(atp)) {
1120 shift = exact_log2(type2aelembytes(T_OBJECT));
1121 cache = AddPNode::Ideal_base_and_offset(load_base->in(Address), phase, cache_offset);
1122 }
1123 if (cache != NULL && base->in(Address)->is_AddP()) {
1124 Node* elements[4];
1125 int count = base->in(Address)->as_AddP()->unpack_offsets(elements, ARRAY_SIZE(elements));
1126 int cache_low;
1127 if (count > 0 && fetch_autobox_base(atp, cache_low)) {
1128 int offset = arrayOopDesc::base_offset_in_bytes(memory_type()) - (cache_low << shift);
1129 // Add up all the offsets making of the address of the load
1130 Node* result = elements[0];
1131 for (int i = 1; i < count; i++) {
1132 result = phase->transform(new (phase->C, 3) AddXNode(result, elements[i]));
1133 }
1134 // Remove the constant offset from the address and then
1135 // remove the scaling of the offset to recover the original index.
1136 result = phase->transform(new (phase->C, 3) AddXNode(result, phase->MakeConX(-offset)));
1137 if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) {
1138 // Peel the shift off directly but wrap it in a dummy node
1139 // since Ideal can't return existing nodes
1140 result = new (phase->C, 3) RShiftXNode(result->in(1), phase->intcon(0));
1141 } else {
1142 result = new (phase->C, 3) RShiftXNode(result, phase->intcon(shift));
1143 }
1144 #ifdef _LP64
1145 result = new (phase->C, 2) ConvL2INode(phase->transform(result));
1146 #endif
1147 return result;
1148 }
1149 }
1150 }
1151 }
1152 return NULL;
1153 }
1154
1155 //------------------------------split_through_phi------------------------------
1156 // Split instance field load through Phi.
1157 Node *LoadNode::split_through_phi(PhaseGVN *phase) {
1158 Node* mem = in(MemNode::Memory);
1159 Node* address = in(MemNode::Address);
1160 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1161 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1162
1163 assert(mem->is_Phi() && (t_oop != NULL) &&
1164 t_oop->is_known_instance_field(), "invalide conditions");
1165
1166 Node *region = mem->in(0);
1167 if (region == NULL) {
1168 return NULL; // Wait stable graph
1169 }
1170 uint cnt = mem->req();
1171 for( uint i = 1; i < cnt; i++ ) {
1172 Node *in = mem->in(i);
1173 if( in == NULL ) {
1174 return NULL; // Wait stable graph
1175 }
1176 }
1177 // Check for loop invariant.
1178 if (cnt == 3) {
1179 for( uint i = 1; i < cnt; i++ ) {
1180 Node *in = mem->in(i);
1181 Node* m = MemNode::optimize_memory_chain(in, addr_t, phase);
1182 if (m == mem) {
1183 set_req(MemNode::Memory, mem->in(cnt - i)); // Skip this phi.
1184 return this;
1185 }
1186 }
1187 }
1188 // Split through Phi (see original code in loopopts.cpp).
1189 assert(phase->C->have_alias_type(addr_t), "instance should have alias type");
1190
1191 // Do nothing here if Identity will find a value
1192 // (to avoid infinite chain of value phis generation).
1193 if ( !phase->eqv(this, this->Identity(phase)) )
1194 return NULL;
1195
1196 // Skip the split if the region dominates some control edge of the address.
1197 if (cnt == 3 && !MemNode::all_controls_dominate(address, region))
1198 return NULL;
1199
1200 const Type* this_type = this->bottom_type();
1201 int this_index = phase->C->get_alias_index(addr_t);
1202 int this_offset = addr_t->offset();
1203 int this_iid = addr_t->is_oopptr()->instance_id();
1204 int wins = 0;
1205 PhaseIterGVN *igvn = phase->is_IterGVN();
1206 Node *phi = new (igvn->C, region->req()) PhiNode(region, this_type, NULL, this_iid, this_index, this_offset);
1207 for( uint i = 1; i < region->req(); i++ ) {
1208 Node *x;
1209 Node* the_clone = NULL;
1210 if( region->in(i) == phase->C->top() ) {
1211 x = phase->C->top(); // Dead path? Use a dead data op
1212 } else {
1213 x = this->clone(); // Else clone up the data op
1214 the_clone = x; // Remember for possible deletion.
1215 // Alter data node to use pre-phi inputs
1216 if( this->in(0) == region ) {
1217 x->set_req( 0, region->in(i) );
1218 } else {
1219 x->set_req( 0, NULL );
1220 }
1221 for( uint j = 1; j < this->req(); j++ ) {
1222 Node *in = this->in(j);
1223 if( in->is_Phi() && in->in(0) == region )
1224 x->set_req( j, in->in(i) ); // Use pre-Phi input for the clone
1225 }
1226 }
1227 // Check for a 'win' on some paths
1228 const Type *t = x->Value(igvn);
1229
1230 bool singleton = t->singleton();
1231
1232 // See comments in PhaseIdealLoop::split_thru_phi().
1233 if( singleton && t == Type::TOP ) {
1234 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1235 }
1236
1237 if( singleton ) {
1238 wins++;
1239 x = igvn->makecon(t);
1240 } else {
1241 // We now call Identity to try to simplify the cloned node.
1242 // Note that some Identity methods call phase->type(this).
1243 // Make sure that the type array is big enough for
1244 // our new node, even though we may throw the node away.
1245 // (This tweaking with igvn only works because x is a new node.)
1246 igvn->set_type(x, t);
1247 // If x is a TypeNode, capture any more-precise type permanently into Node
1248 // othewise it will be not updated during igvn->transform since
1249 // igvn->type(x) is set to x->Value() already.
1250 x->raise_bottom_type(t);
1251 Node *y = x->Identity(igvn);
1252 if( y != x ) {
1253 wins++;
1254 x = y;
1255 } else {
1256 y = igvn->hash_find(x);
1257 if( y ) {
1258 wins++;
1259 x = y;
1260 } else {
1261 // Else x is a new node we are keeping
1262 // We do not need register_new_node_with_optimizer
1263 // because set_type has already been called.
1264 igvn->_worklist.push(x);
1265 }
1266 }
1267 }
1268 if (x != the_clone && the_clone != NULL)
1269 igvn->remove_dead_node(the_clone);
1270 phi->set_req(i, x);
1271 }
1272 if( wins > 0 ) {
1273 // Record Phi
1274 igvn->register_new_node_with_optimizer(phi);
1275 return phi;
1276 }
1277 igvn->remove_dead_node(phi);
1278 return NULL;
1279 }
1280
1281 //------------------------------Ideal------------------------------------------
1282 // If the load is from Field memory and the pointer is non-null, we can
1283 // zero out the control input.
1284 // If the offset is constant and the base is an object allocation,
1285 // try to hook me up to the exact initializing store.
1286 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1287 Node* p = MemNode::Ideal_common(phase, can_reshape);
1288 if (p) return (p == NodeSentinel) ? NULL : p;
1289
1290 Node* ctrl = in(MemNode::Control);
1291 Node* address = in(MemNode::Address);
1292
1293 // Skip up past a SafePoint control. Cannot do this for Stores because
1294 // pointer stores & cardmarks must stay on the same side of a SafePoint.
1295 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint &&
1296 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw ) {
1297 ctrl = ctrl->in(0);
1298 set_req(MemNode::Control,ctrl);
1299 }
1300
1301 // Check for useless control edge in some common special cases
1302 if (in(MemNode::Control) != NULL) {
1303 intptr_t ignore = 0;
1304 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1305 if (base != NULL
1306 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1307 && all_controls_dominate(base, phase->C->start())
1308 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
1309 // A method-invariant, non-null address (constant or 'this' argument).
1310 set_req(MemNode::Control, NULL);
1311 }
1312 }
1313
1314 if (EliminateAutoBox && can_reshape && in(Address)->is_AddP()) {
1315 Node* base = in(Address)->in(AddPNode::Base);
1316 if (base != NULL) {
1317 Compile::AliasType* atp = phase->C->alias_type(adr_type());
1318 if (is_autobox_object(atp)) {
1319 Node* result = eliminate_autobox(phase);
1320 if (result != NULL) return result;
1321 }
1322 }
1323 }
1324
1325 Node* mem = in(MemNode::Memory);
1326 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1327
1328 if (addr_t != NULL) {
1329 // try to optimize our memory input
1330 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, phase);
1331 if (opt_mem != mem) {
1332 set_req(MemNode::Memory, opt_mem);
1333 if (phase->type( opt_mem ) == Type::TOP) return NULL;
1334 return this;
1335 }
1336 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1337 if (can_reshape && opt_mem->is_Phi() &&
1338 (t_oop != NULL) && t_oop->is_known_instance_field()) {
1339 // Split instance field load through Phi.
1340 Node* result = split_through_phi(phase);
1341 if (result != NULL) return result;
1342 }
1343 }
1344
1345 // Check for prior store with a different base or offset; make Load
1346 // independent. Skip through any number of them. Bail out if the stores
1347 // are in an endless dead cycle and report no progress. This is a key
1348 // transform for Reflection. However, if after skipping through the Stores
1349 // we can't then fold up against a prior store do NOT do the transform as
1350 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
1351 // array memory alive twice: once for the hoisted Load and again after the
1352 // bypassed Store. This situation only works if EVERYBODY who does
1353 // anti-dependence work knows how to bypass. I.e. we need all
1354 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
1355 // the alias index stuff. So instead, peek through Stores and IFF we can
1356 // fold up, do so.
1357 Node* prev_mem = find_previous_store(phase);
1358 // Steps (a), (b): Walk past independent stores to find an exact match.
1359 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) {
1360 // (c) See if we can fold up on the spot, but don't fold up here.
1361 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
1362 // just return a prior value, which is done by Identity calls.
1363 if (can_see_stored_value(prev_mem, phase)) {
1364 // Make ready for step (d):
1365 set_req(MemNode::Memory, prev_mem);
1366 return this;
1367 }
1368 }
1369
1370 return NULL; // No further progress
1371 }
1372
1373 // Helper to recognize certain Klass fields which are invariant across
1374 // some group of array types (e.g., int[] or all T[] where T < Object).
1375 const Type*
1376 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1377 ciKlass* klass) const {
1378 if (tkls->offset() == Klass::modifier_flags_offset_in_bytes() + (int)sizeof(oopDesc)) {
1379 // The field is Klass::_modifier_flags. Return its (constant) value.
1380 // (Folds up the 2nd indirection in aClassConstant.getModifiers().)
1381 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags");
1382 return TypeInt::make(klass->modifier_flags());
1383 }
1384 if (tkls->offset() == Klass::access_flags_offset_in_bytes() + (int)sizeof(oopDesc)) {
1385 // The field is Klass::_access_flags. Return its (constant) value.
1386 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1387 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags");
1388 return TypeInt::make(klass->access_flags());
1389 }
1390 if (tkls->offset() == Klass::layout_helper_offset_in_bytes() + (int)sizeof(oopDesc)) {
1391 // The field is Klass::_layout_helper. Return its constant value if known.
1392 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper");
1393 return TypeInt::make(klass->layout_helper());
1394 }
1395
1396 // No match.
1397 return NULL;
1398 }
1399
1400 //------------------------------Value-----------------------------------------
1401 const Type *LoadNode::Value( PhaseTransform *phase ) const {
1402 // Either input is TOP ==> the result is TOP
1403 Node* mem = in(MemNode::Memory);
1404 const Type *t1 = phase->type(mem);
1405 if (t1 == Type::TOP) return Type::TOP;
1406 Node* adr = in(MemNode::Address);
1407 const TypePtr* tp = phase->type(adr)->isa_ptr();
1408 if (tp == NULL || tp->empty()) return Type::TOP;
1409 int off = tp->offset();
1410 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
1411
1412 // Try to guess loaded type from pointer type
1413 if (tp->base() == Type::AryPtr) {
1414 const Type *t = tp->is_aryptr()->elem();
1415 // Don't do this for integer types. There is only potential profit if
1416 // the element type t is lower than _type; that is, for int types, if _type is
1417 // more restrictive than t. This only happens here if one is short and the other
1418 // char (both 16 bits), and in those cases we've made an intentional decision
1419 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
1420 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
1421 //
1422 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
1423 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
1424 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
1425 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
1426 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
1427 // In fact, that could have been the original type of p1, and p1 could have
1428 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
1429 // expression (LShiftL quux 3) independently optimized to the constant 8.
1430 if ((t->isa_int() == NULL) && (t->isa_long() == NULL)
1431 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
1432 // t might actually be lower than _type, if _type is a unique
1433 // concrete subclass of abstract class t.
1434 // Make sure the reference is not into the header, by comparing
1435 // the offset against the offset of the start of the array's data.
1436 // Different array types begin at slightly different offsets (12 vs. 16).
1437 // We choose T_BYTE as an example base type that is least restrictive
1438 // as to alignment, which will therefore produce the smallest
1439 // possible base offset.
1440 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
1441 if ((uint)off >= (uint)min_base_off) { // is the offset beyond the header?
1442 const Type* jt = t->join(_type);
1443 // In any case, do not allow the join, per se, to empty out the type.
1444 if (jt->empty() && !t->empty()) {
1445 // This can happen if a interface-typed array narrows to a class type.
1446 jt = _type;
1447 }
1448
1449 if (EliminateAutoBox) {
1450 // The pointers in the autobox arrays are always non-null
1451 Node* base = in(Address)->in(AddPNode::Base);
1452 if (base != NULL) {
1453 Compile::AliasType* atp = phase->C->alias_type(base->adr_type());
1454 if (is_autobox_cache(atp)) {
1455 return jt->join(TypePtr::NOTNULL)->is_ptr();
1456 }
1457 }
1458 }
1459 return jt;
1460 }
1461 }
1462 } else if (tp->base() == Type::InstPtr) {
1463 assert( off != Type::OffsetBot ||
1464 // arrays can be cast to Objects
1465 tp->is_oopptr()->klass()->is_java_lang_Object() ||
1466 // unsafe field access may not have a constant offset
1467 phase->C->has_unsafe_access(),
1468 "Field accesses must be precise" );
1469 // For oop loads, we expect the _type to be precise
1470 } else if (tp->base() == Type::KlassPtr) {
1471 assert( off != Type::OffsetBot ||
1472 // arrays can be cast to Objects
1473 tp->is_klassptr()->klass()->is_java_lang_Object() ||
1474 // also allow array-loading from the primary supertype
1475 // array during subtype checks
1476 Opcode() == Op_LoadKlass,
1477 "Field accesses must be precise" );
1478 // For klass/static loads, we expect the _type to be precise
1479 }
1480
1481 const TypeKlassPtr *tkls = tp->isa_klassptr();
1482 if (tkls != NULL && !StressReflectiveCode) {
1483 ciKlass* klass = tkls->klass();
1484 if (klass->is_loaded() && tkls->klass_is_exact()) {
1485 // We are loading a field from a Klass metaobject whose identity
1486 // is known at compile time (the type is "exact" or "precise").
1487 // Check for fields we know are maintained as constants by the VM.
1488 if (tkls->offset() == Klass::super_check_offset_offset_in_bytes() + (int)sizeof(oopDesc)) {
1489 // The field is Klass::_super_check_offset. Return its (constant) value.
1490 // (Folds up type checking code.)
1491 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
1492 return TypeInt::make(klass->super_check_offset());
1493 }
1494 // Compute index into primary_supers array
1495 juint depth = (tkls->offset() - (Klass::primary_supers_offset_in_bytes() + (int)sizeof(oopDesc))) / sizeof(klassOop);
1496 // Check for overflowing; use unsigned compare to handle the negative case.
1497 if( depth < ciKlass::primary_super_limit() ) {
1498 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1499 // (Folds up type checking code.)
1500 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1501 ciKlass *ss = klass->super_of_depth(depth);
1502 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1503 }
1504 const Type* aift = load_array_final_field(tkls, klass);
1505 if (aift != NULL) return aift;
1506 if (tkls->offset() == in_bytes(arrayKlass::component_mirror_offset()) + (int)sizeof(oopDesc)
1507 && klass->is_array_klass()) {
1508 // The field is arrayKlass::_component_mirror. Return its (constant) value.
1509 // (Folds up aClassConstant.getComponentType, common in Arrays.copyOf.)
1510 assert(Opcode() == Op_LoadP, "must load an oop from _component_mirror");
1511 return TypeInstPtr::make(klass->as_array_klass()->component_mirror());
1512 }
1513 if (tkls->offset() == Klass::java_mirror_offset_in_bytes() + (int)sizeof(oopDesc)) {
1514 // The field is Klass::_java_mirror. Return its (constant) value.
1515 // (Folds up the 2nd indirection in anObjConstant.getClass().)
1516 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
1517 return TypeInstPtr::make(klass->java_mirror());
1518 }
1519 }
1520
1521 // We can still check if we are loading from the primary_supers array at a
1522 // shallow enough depth. Even though the klass is not exact, entries less
1523 // than or equal to its super depth are correct.
1524 if (klass->is_loaded() ) {
1525 ciType *inner = klass->klass();
1526 while( inner->is_obj_array_klass() )
1527 inner = inner->as_obj_array_klass()->base_element_type();
1528 if( inner->is_instance_klass() &&
1529 !inner->as_instance_klass()->flags().is_interface() ) {
1530 // Compute index into primary_supers array
1531 juint depth = (tkls->offset() - (Klass::primary_supers_offset_in_bytes() + (int)sizeof(oopDesc))) / sizeof(klassOop);
1532 // Check for overflowing; use unsigned compare to handle the negative case.
1533 if( depth < ciKlass::primary_super_limit() &&
1534 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case
1535 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1536 // (Folds up type checking code.)
1537 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1538 ciKlass *ss = klass->super_of_depth(depth);
1539 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1540 }
1541 }
1542 }
1543
1544 // If the type is enough to determine that the thing is not an array,
1545 // we can give the layout_helper a positive interval type.
1546 // This will help short-circuit some reflective code.
1547 if (tkls->offset() == Klass::layout_helper_offset_in_bytes() + (int)sizeof(oopDesc)
1548 && !klass->is_array_klass() // not directly typed as an array
1549 && !klass->is_interface() // specifically not Serializable & Cloneable
1550 && !klass->is_java_lang_Object() // not the supertype of all T[]
1551 ) {
1552 // Note: When interfaces are reliable, we can narrow the interface
1553 // test to (klass != Serializable && klass != Cloneable).
1554 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
1555 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
1556 // The key property of this type is that it folds up tests
1557 // for array-ness, since it proves that the layout_helper is positive.
1558 // Thus, a generic value like the basic object layout helper works fine.
1559 return TypeInt::make(min_size, max_jint, Type::WidenMin);
1560 }
1561 }
1562
1563 // If we are loading from a freshly-allocated object, produce a zero,
1564 // if the load is provably beyond the header of the object.
1565 // (Also allow a variable load from a fresh array to produce zero.)
1566 if (ReduceFieldZeroing) {
1567 Node* value = can_see_stored_value(mem,phase);
1568 if (value != NULL && value->is_Con())
1569 return value->bottom_type();
1570 }
1571
1572 const TypeOopPtr *tinst = tp->isa_oopptr();
1573 if (tinst != NULL && tinst->is_known_instance_field()) {
1574 // If we have an instance type and our memory input is the
1575 // programs's initial memory state, there is no matching store,
1576 // so just return a zero of the appropriate type
1577 Node *mem = in(MemNode::Memory);
1578 if (mem->is_Parm() && mem->in(0)->is_Start()) {
1579 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
1580 return Type::get_zero_type(_type->basic_type());
1581 }
1582 }
1583 return _type;
1584 }
1585
1586 //------------------------------match_edge-------------------------------------
1587 // Do we Match on this edge index or not? Match only the address.
1588 uint LoadNode::match_edge(uint idx) const {
1589 return idx == MemNode::Address;
1590 }
1591
1592 //--------------------------LoadBNode::Ideal--------------------------------------
1593 //
1594 // If the previous store is to the same address as this load,
1595 // and the value stored was larger than a byte, replace this load
1596 // with the value stored truncated to a byte. If no truncation is
1597 // needed, the replacement is done in LoadNode::Identity().
1598 //
1599 Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1600 Node* mem = in(MemNode::Memory);
1601 Node* value = can_see_stored_value(mem,phase);
1602 if( value && !phase->type(value)->higher_equal( _type ) ) {
1603 Node *result = phase->transform( new (phase->C, 3) LShiftINode(value, phase->intcon(24)) );
1604 return new (phase->C, 3) RShiftINode(result, phase->intcon(24));
1605 }
1606 // Identity call will handle the case where truncation is not needed.
1607 return LoadNode::Ideal(phase, can_reshape);
1608 }
1609
1610 //--------------------------LoadUSNode::Ideal-------------------------------------
1611 //
1612 // If the previous store is to the same address as this load,
1613 // and the value stored was larger than a char, replace this load
1614 // with the value stored truncated to a char. If no truncation is
1615 // needed, the replacement is done in LoadNode::Identity().
1616 //
1617 Node *LoadUSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1618 Node* mem = in(MemNode::Memory);
1619 Node* value = can_see_stored_value(mem,phase);
1620 if( value && !phase->type(value)->higher_equal( _type ) )
1621 return new (phase->C, 3) AndINode(value,phase->intcon(0xFFFF));
1622 // Identity call will handle the case where truncation is not needed.
1623 return LoadNode::Ideal(phase, can_reshape);
1624 }
1625
1626 //--------------------------LoadSNode::Ideal--------------------------------------
1627 //
1628 // If the previous store is to the same address as this load,
1629 // and the value stored was larger than a short, replace this load
1630 // with the value stored truncated to a short. If no truncation is
1631 // needed, the replacement is done in LoadNode::Identity().
1632 //
1633 Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1634 Node* mem = in(MemNode::Memory);
1635 Node* value = can_see_stored_value(mem,phase);
1636 if( value && !phase->type(value)->higher_equal( _type ) ) {
1637 Node *result = phase->transform( new (phase->C, 3) LShiftINode(value, phase->intcon(16)) );
1638 return new (phase->C, 3) RShiftINode(result, phase->intcon(16));
1639 }
1640 // Identity call will handle the case where truncation is not needed.
1641 return LoadNode::Ideal(phase, can_reshape);
1642 }
1643
1644 //=============================================================================
1645 //----------------------------LoadKlassNode::make------------------------------
1646 // Polymorphic factory method:
1647 Node *LoadKlassNode::make( PhaseGVN& gvn, Node *mem, Node *adr, const TypePtr* at, const TypeKlassPtr *tk ) {
1648 Compile* C = gvn.C;
1649 Node *ctl = NULL;
1650 // sanity check the alias category against the created node type
1651 const TypeOopPtr *adr_type = adr->bottom_type()->isa_oopptr();
1652 assert(adr_type != NULL, "expecting TypeOopPtr");
1653 #ifdef _LP64
1654 if (adr_type->is_ptr_to_narrowoop()) {
1655 Node* load_klass = gvn.transform(new (C, 3) LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowoop()));
1656 return new (C, 2) DecodeNNode(load_klass, load_klass->bottom_type()->make_ptr());
1657 }
1658 #endif
1659 assert(!adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
1660 return new (C, 3) LoadKlassNode(ctl, mem, adr, at, tk);
1661 }
1662
1663 //------------------------------Value------------------------------------------
1664 const Type *LoadKlassNode::Value( PhaseTransform *phase ) const {
1665 return klass_value_common(phase);
1666 }
1667
1668 const Type *LoadNode::klass_value_common( PhaseTransform *phase ) const {
1669 // Either input is TOP ==> the result is TOP
1670 const Type *t1 = phase->type( in(MemNode::Memory) );
1671 if (t1 == Type::TOP) return Type::TOP;
1672 Node *adr = in(MemNode::Address);
1673 const Type *t2 = phase->type( adr );
1674 if (t2 == Type::TOP) return Type::TOP;
1675 const TypePtr *tp = t2->is_ptr();
1676 if (TypePtr::above_centerline(tp->ptr()) ||
1677 tp->ptr() == TypePtr::Null) return Type::TOP;
1678
1679 // Return a more precise klass, if possible
1680 const TypeInstPtr *tinst = tp->isa_instptr();
1681 if (tinst != NULL) {
1682 ciInstanceKlass* ik = tinst->klass()->as_instance_klass();
1683 int offset = tinst->offset();
1684 if (ik == phase->C->env()->Class_klass()
1685 && (offset == java_lang_Class::klass_offset_in_bytes() ||
1686 offset == java_lang_Class::array_klass_offset_in_bytes())) {
1687 // We are loading a special hidden field from a Class mirror object,
1688 // the field which points to the VM's Klass metaobject.
1689 ciType* t = tinst->java_mirror_type();
1690 // java_mirror_type returns non-null for compile-time Class constants.
1691 if (t != NULL) {
1692 // constant oop => constant klass
1693 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
1694 return TypeKlassPtr::make(ciArrayKlass::make(t));
1695 }
1696 if (!t->is_klass()) {
1697 // a primitive Class (e.g., int.class) has NULL for a klass field
1698 return TypePtr::NULL_PTR;
1699 }
1700 // (Folds up the 1st indirection in aClassConstant.getModifiers().)
1701 return TypeKlassPtr::make(t->as_klass());
1702 }
1703 // non-constant mirror, so we can't tell what's going on
1704 }
1705 if( !ik->is_loaded() )
1706 return _type; // Bail out if not loaded
1707 if (offset == oopDesc::klass_offset_in_bytes()) {
1708 if (tinst->klass_is_exact()) {
1709 return TypeKlassPtr::make(ik);
1710 }
1711 // See if we can become precise: no subklasses and no interface
1712 // (Note: We need to support verified interfaces.)
1713 if (!ik->is_interface() && !ik->has_subklass()) {
1714 //assert(!UseExactTypes, "this code should be useless with exact types");
1715 // Add a dependence; if any subclass added we need to recompile
1716 if (!ik->is_final()) {
1717 // %%% should use stronger assert_unique_concrete_subtype instead
1718 phase->C->dependencies()->assert_leaf_type(ik);
1719 }
1720 // Return precise klass
1721 return TypeKlassPtr::make(ik);
1722 }
1723
1724 // Return root of possible klass
1725 return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/);
1726 }
1727 }
1728
1729 // Check for loading klass from an array
1730 const TypeAryPtr *tary = tp->isa_aryptr();
1731 if( tary != NULL ) {
1732 ciKlass *tary_klass = tary->klass();
1733 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP
1734 && tary->offset() == oopDesc::klass_offset_in_bytes()) {
1735 if (tary->klass_is_exact()) {
1736 return TypeKlassPtr::make(tary_klass);
1737 }
1738 ciArrayKlass *ak = tary->klass()->as_array_klass();
1739 // If the klass is an object array, we defer the question to the
1740 // array component klass.
1741 if( ak->is_obj_array_klass() ) {
1742 assert( ak->is_loaded(), "" );
1743 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass();
1744 if( base_k->is_loaded() && base_k->is_instance_klass() ) {
1745 ciInstanceKlass* ik = base_k->as_instance_klass();
1746 // See if we can become precise: no subklasses and no interface
1747 if (!ik->is_interface() && !ik->has_subklass()) {
1748 //assert(!UseExactTypes, "this code should be useless with exact types");
1749 // Add a dependence; if any subclass added we need to recompile
1750 if (!ik->is_final()) {
1751 phase->C->dependencies()->assert_leaf_type(ik);
1752 }
1753 // Return precise array klass
1754 return TypeKlassPtr::make(ak);
1755 }
1756 }
1757 return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/);
1758 } else { // Found a type-array?
1759 //assert(!UseExactTypes, "this code should be useless with exact types");
1760 assert( ak->is_type_array_klass(), "" );
1761 return TypeKlassPtr::make(ak); // These are always precise
1762 }
1763 }
1764 }
1765
1766 // Check for loading klass from an array klass
1767 const TypeKlassPtr *tkls = tp->isa_klassptr();
1768 if (tkls != NULL && !StressReflectiveCode) {
1769 ciKlass* klass = tkls->klass();
1770 if( !klass->is_loaded() )
1771 return _type; // Bail out if not loaded
1772 if( klass->is_obj_array_klass() &&
1773 (uint)tkls->offset() == objArrayKlass::element_klass_offset_in_bytes() + sizeof(oopDesc)) {
1774 ciKlass* elem = klass->as_obj_array_klass()->element_klass();
1775 // // Always returning precise element type is incorrect,
1776 // // e.g., element type could be object and array may contain strings
1777 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
1778
1779 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
1780 // according to the element type's subclassing.
1781 return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/);
1782 }
1783 if( klass->is_instance_klass() && tkls->klass_is_exact() &&
1784 (uint)tkls->offset() == Klass::super_offset_in_bytes() + sizeof(oopDesc)) {
1785 ciKlass* sup = klass->as_instance_klass()->super();
1786 // The field is Klass::_super. Return its (constant) value.
1787 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
1788 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR;
1789 }
1790 }
1791
1792 // Bailout case
1793 return LoadNode::Value(phase);
1794 }
1795
1796 //------------------------------Identity---------------------------------------
1797 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
1798 // Also feed through the klass in Allocate(...klass...)._klass.
1799 Node* LoadKlassNode::Identity( PhaseTransform *phase ) {
1800 return klass_identity_common(phase);
1801 }
1802
1803 Node* LoadNode::klass_identity_common(PhaseTransform *phase ) {
1804 Node* x = LoadNode::Identity(phase);
1805 if (x != this) return x;
1806
1807 // Take apart the address into an oop and and offset.
1808 // Return 'this' if we cannot.
1809 Node* adr = in(MemNode::Address);
1810 intptr_t offset = 0;
1811 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
1812 if (base == NULL) return this;
1813 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
1814 if (toop == NULL) return this;
1815
1816 // We can fetch the klass directly through an AllocateNode.
1817 // This works even if the klass is not constant (clone or newArray).
1818 if (offset == oopDesc::klass_offset_in_bytes()) {
1819 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
1820 if (allocated_klass != NULL) {
1821 return allocated_klass;
1822 }
1823 }
1824
1825 // Simplify k.java_mirror.as_klass to plain k, where k is a klassOop.
1826 // Simplify ak.component_mirror.array_klass to plain ak, ak an arrayKlass.
1827 // See inline_native_Class_query for occurrences of these patterns.
1828 // Java Example: x.getClass().isAssignableFrom(y)
1829 // Java Example: Array.newInstance(x.getClass().getComponentType(), n)
1830 //
1831 // This improves reflective code, often making the Class
1832 // mirror go completely dead. (Current exception: Class
1833 // mirrors may appear in debug info, but we could clean them out by
1834 // introducing a new debug info operator for klassOop.java_mirror).
1835 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass()
1836 && (offset == java_lang_Class::klass_offset_in_bytes() ||
1837 offset == java_lang_Class::array_klass_offset_in_bytes())) {
1838 // We are loading a special hidden field from a Class mirror,
1839 // the field which points to its Klass or arrayKlass metaobject.
1840 if (base->is_Load()) {
1841 Node* adr2 = base->in(MemNode::Address);
1842 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
1843 if (tkls != NULL && !tkls->empty()
1844 && (tkls->klass()->is_instance_klass() ||
1845 tkls->klass()->is_array_klass())
1846 && adr2->is_AddP()
1847 ) {
1848 int mirror_field = Klass::java_mirror_offset_in_bytes();
1849 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
1850 mirror_field = in_bytes(arrayKlass::component_mirror_offset());
1851 }
1852 if (tkls->offset() == mirror_field + (int)sizeof(oopDesc)) {
1853 return adr2->in(AddPNode::Base);
1854 }
1855 }
1856 }
1857 }
1858
1859 return this;
1860 }
1861
1862
1863 //------------------------------Value------------------------------------------
1864 const Type *LoadNKlassNode::Value( PhaseTransform *phase ) const {
1865 const Type *t = klass_value_common(phase);
1866 if (t == Type::TOP)
1867 return t;
1868
1869 return t->make_narrowoop();
1870 }
1871
1872 //------------------------------Identity---------------------------------------
1873 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
1874 // Also feed through the klass in Allocate(...klass...)._klass.
1875 Node* LoadNKlassNode::Identity( PhaseTransform *phase ) {
1876 Node *x = klass_identity_common(phase);
1877
1878 const Type *t = phase->type( x );
1879 if( t == Type::TOP ) return x;
1880 if( t->isa_narrowoop()) return x;
1881
1882 return phase->transform(new (phase->C, 2) EncodePNode(x, t->make_narrowoop()));
1883 }
1884
1885 //------------------------------Value-----------------------------------------
1886 const Type *LoadRangeNode::Value( PhaseTransform *phase ) const {
1887 // Either input is TOP ==> the result is TOP
1888 const Type *t1 = phase->type( in(MemNode::Memory) );
1889 if( t1 == Type::TOP ) return Type::TOP;
1890 Node *adr = in(MemNode::Address);
1891 const Type *t2 = phase->type( adr );
1892 if( t2 == Type::TOP ) return Type::TOP;
1893 const TypePtr *tp = t2->is_ptr();
1894 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
1895 const TypeAryPtr *tap = tp->isa_aryptr();
1896 if( !tap ) return _type;
1897 return tap->size();
1898 }
1899
1900 //-------------------------------Ideal---------------------------------------
1901 // Feed through the length in AllocateArray(...length...)._length.
1902 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1903 Node* p = MemNode::Ideal_common(phase, can_reshape);
1904 if (p) return (p == NodeSentinel) ? NULL : p;
1905
1906 // Take apart the address into an oop and and offset.
1907 // Return 'this' if we cannot.
1908 Node* adr = in(MemNode::Address);
1909 intptr_t offset = 0;
1910 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
1911 if (base == NULL) return NULL;
1912 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
1913 if (tary == NULL) return NULL;
1914
1915 // We can fetch the length directly through an AllocateArrayNode.
1916 // This works even if the length is not constant (clone or newArray).
1917 if (offset == arrayOopDesc::length_offset_in_bytes()) {
1918 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
1919 if (alloc != NULL) {
1920 Node* allocated_length = alloc->Ideal_length();
1921 Node* len = alloc->make_ideal_length(tary, phase);
1922 if (allocated_length != len) {
1923 // New CastII improves on this.
1924 return len;
1925 }
1926 }
1927 }
1928
1929 return NULL;
1930 }
1931
1932 //------------------------------Identity---------------------------------------
1933 // Feed through the length in AllocateArray(...length...)._length.
1934 Node* LoadRangeNode::Identity( PhaseTransform *phase ) {
1935 Node* x = LoadINode::Identity(phase);
1936 if (x != this) return x;
1937
1938 // Take apart the address into an oop and and offset.
1939 // Return 'this' if we cannot.
1940 Node* adr = in(MemNode::Address);
1941 intptr_t offset = 0;
1942 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
1943 if (base == NULL) return this;
1944 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
1945 if (tary == NULL) return this;
1946
1947 // We can fetch the length directly through an AllocateArrayNode.
1948 // This works even if the length is not constant (clone or newArray).
1949 if (offset == arrayOopDesc::length_offset_in_bytes()) {
1950 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
1951 if (alloc != NULL) {
1952 Node* allocated_length = alloc->Ideal_length();
1953 // Do not allow make_ideal_length to allocate a CastII node.
1954 Node* len = alloc->make_ideal_length(tary, phase, false);
1955 if (allocated_length == len) {
1956 // Return allocated_length only if it would not be improved by a CastII.
1957 return allocated_length;
1958 }
1959 }
1960 }
1961
1962 return this;
1963
1964 }
1965
1966 //=============================================================================
1967 //---------------------------StoreNode::make-----------------------------------
1968 // Polymorphic factory method:
1969 StoreNode* StoreNode::make( PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt ) {
1970 Compile* C = gvn.C;
1971
1972 switch (bt) {
1973 case T_BOOLEAN:
1974 case T_BYTE: return new (C, 4) StoreBNode(ctl, mem, adr, adr_type, val);
1975 case T_INT: return new (C, 4) StoreINode(ctl, mem, adr, adr_type, val);
1976 case T_CHAR:
1977 case T_SHORT: return new (C, 4) StoreCNode(ctl, mem, adr, adr_type, val);
1978 case T_LONG: return new (C, 4) StoreLNode(ctl, mem, adr, adr_type, val);
1979 case T_FLOAT: return new (C, 4) StoreFNode(ctl, mem, adr, adr_type, val);
1980 case T_DOUBLE: return new (C, 4) StoreDNode(ctl, mem, adr, adr_type, val);
1981 case T_ADDRESS:
1982 case T_OBJECT:
1983 #ifdef _LP64
1984 if (adr->bottom_type()->is_ptr_to_narrowoop() ||
1985 (UseCompressedOops && val->bottom_type()->isa_klassptr() &&
1986 adr->bottom_type()->isa_rawptr())) {
1987 val = gvn.transform(new (C, 2) EncodePNode(val, val->bottom_type()->make_narrowoop()));
1988 return new (C, 4) StoreNNode(ctl, mem, adr, adr_type, val);
1989 } else
1990 #endif
1991 {
1992 return new (C, 4) StorePNode(ctl, mem, adr, adr_type, val);
1993 }
1994 }
1995 ShouldNotReachHere();
1996 return (StoreNode*)NULL;
1997 }
1998
1999 StoreLNode* StoreLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val) {
2000 bool require_atomic = true;
2001 return new (C, 4) StoreLNode(ctl, mem, adr, adr_type, val, require_atomic);
2002 }
2003
2004
2005 //--------------------------bottom_type----------------------------------------
2006 const Type *StoreNode::bottom_type() const {
2007 return Type::MEMORY;
2008 }
2009
2010 //------------------------------hash-------------------------------------------
2011 uint StoreNode::hash() const {
2012 // unroll addition of interesting fields
2013 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2014
2015 // Since they are not commoned, do not hash them:
2016 return NO_HASH;
2017 }
2018
2019 //------------------------------Ideal------------------------------------------
2020 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
2021 // When a store immediately follows a relevant allocation/initialization,
2022 // try to capture it into the initialization, or hoist it above.
2023 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2024 Node* p = MemNode::Ideal_common(phase, can_reshape);
2025 if (p) return (p == NodeSentinel) ? NULL : p;
2026
2027 Node* mem = in(MemNode::Memory);
2028 Node* address = in(MemNode::Address);
2029
2030 // Back-to-back stores to same address? Fold em up.
2031 // Generally unsafe if I have intervening uses...
2032 if (mem->is_Store() && phase->eqv_uncast(mem->in(MemNode::Address), address)) {
2033 // Looking at a dead closed cycle of memory?
2034 assert(mem != mem->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
2035
2036 assert(Opcode() == mem->Opcode() ||
2037 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw,
2038 "no mismatched stores, except on raw memory");
2039
2040 if (mem->outcnt() == 1 && // check for intervening uses
2041 mem->as_Store()->memory_size() <= this->memory_size()) {
2042 // If anybody other than 'this' uses 'mem', we cannot fold 'mem' away.
2043 // For example, 'mem' might be the final state at a conditional return.
2044 // Or, 'mem' might be used by some node which is live at the same time
2045 // 'this' is live, which might be unschedulable. So, require exactly
2046 // ONE user, the 'this' store, until such time as we clone 'mem' for
2047 // each of 'mem's uses (thus making the exactly-1-user-rule hold true).
2048 if (can_reshape) { // (%%% is this an anachronism?)
2049 set_req_X(MemNode::Memory, mem->in(MemNode::Memory),
2050 phase->is_IterGVN());
2051 } else {
2052 // It's OK to do this in the parser, since DU info is always accurate,
2053 // and the parser always refers to nodes via SafePointNode maps.
2054 set_req(MemNode::Memory, mem->in(MemNode::Memory));
2055 }
2056 return this;
2057 }
2058 }
2059
2060 // Capture an unaliased, unconditional, simple store into an initializer.
2061 // Or, if it is independent of the allocation, hoist it above the allocation.
2062 if (ReduceFieldZeroing && /*can_reshape &&*/
2063 mem->is_Proj() && mem->in(0)->is_Initialize()) {
2064 InitializeNode* init = mem->in(0)->as_Initialize();
2065 intptr_t offset = init->can_capture_store(this, phase);
2066 if (offset > 0) {
2067 Node* moved = init->capture_store(this, offset, phase);
2068 // If the InitializeNode captured me, it made a raw copy of me,
2069 // and I need to disappear.
2070 if (moved != NULL) {
2071 // %%% hack to ensure that Ideal returns a new node:
2072 mem = MergeMemNode::make(phase->C, mem);
2073 return mem; // fold me away
2074 }
2075 }
2076 }
2077
2078 return NULL; // No further progress
2079 }
2080
2081 //------------------------------Value-----------------------------------------
2082 const Type *StoreNode::Value( PhaseTransform *phase ) const {
2083 // Either input is TOP ==> the result is TOP
2084 const Type *t1 = phase->type( in(MemNode::Memory) );
2085 if( t1 == Type::TOP ) return Type::TOP;
2086 const Type *t2 = phase->type( in(MemNode::Address) );
2087 if( t2 == Type::TOP ) return Type::TOP;
2088 const Type *t3 = phase->type( in(MemNode::ValueIn) );
2089 if( t3 == Type::TOP ) return Type::TOP;
2090 return Type::MEMORY;
2091 }
2092
2093 //------------------------------Identity---------------------------------------
2094 // Remove redundant stores:
2095 // Store(m, p, Load(m, p)) changes to m.
2096 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
2097 Node *StoreNode::Identity( PhaseTransform *phase ) {
2098 Node* mem = in(MemNode::Memory);
2099 Node* adr = in(MemNode::Address);
2100 Node* val = in(MemNode::ValueIn);
2101
2102 // Load then Store? Then the Store is useless
2103 if (val->is_Load() &&
2104 phase->eqv_uncast( val->in(MemNode::Address), adr ) &&
2105 phase->eqv_uncast( val->in(MemNode::Memory ), mem ) &&
2106 val->as_Load()->store_Opcode() == Opcode()) {
2107 return mem;
2108 }
2109
2110 // Two stores in a row of the same value?
2111 if (mem->is_Store() &&
2112 phase->eqv_uncast( mem->in(MemNode::Address), adr ) &&
2113 phase->eqv_uncast( mem->in(MemNode::ValueIn), val ) &&
2114 mem->Opcode() == Opcode()) {
2115 return mem;
2116 }
2117
2118 // Store of zero anywhere into a freshly-allocated object?
2119 // Then the store is useless.
2120 // (It must already have been captured by the InitializeNode.)
2121 if (ReduceFieldZeroing && phase->type(val)->is_zero_type()) {
2122 // a newly allocated object is already all-zeroes everywhere
2123 if (mem->is_Proj() && mem->in(0)->is_Allocate()) {
2124 return mem;
2125 }
2126
2127 // the store may also apply to zero-bits in an earlier object
2128 Node* prev_mem = find_previous_store(phase);
2129 // Steps (a), (b): Walk past independent stores to find an exact match.
2130 if (prev_mem != NULL) {
2131 Node* prev_val = can_see_stored_value(prev_mem, phase);
2132 if (prev_val != NULL && phase->eqv(prev_val, val)) {
2133 // prev_val and val might differ by a cast; it would be good
2134 // to keep the more informative of the two.
2135 return mem;
2136 }
2137 }
2138 }
2139
2140 return this;
2141 }
2142
2143 //------------------------------match_edge-------------------------------------
2144 // Do we Match on this edge index or not? Match only memory & value
2145 uint StoreNode::match_edge(uint idx) const {
2146 return idx == MemNode::Address || idx == MemNode::ValueIn;
2147 }
2148
2149 //------------------------------cmp--------------------------------------------
2150 // Do not common stores up together. They generally have to be split
2151 // back up anyways, so do not bother.
2152 uint StoreNode::cmp( const Node &n ) const {
2153 return (&n == this); // Always fail except on self
2154 }
2155
2156 //------------------------------Ideal_masked_input-----------------------------
2157 // Check for a useless mask before a partial-word store
2158 // (StoreB ... (AndI valIn conIa) )
2159 // If (conIa & mask == mask) this simplifies to
2160 // (StoreB ... (valIn) )
2161 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
2162 Node *val = in(MemNode::ValueIn);
2163 if( val->Opcode() == Op_AndI ) {
2164 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2165 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
2166 set_req(MemNode::ValueIn, val->in(1));
2167 return this;
2168 }
2169 }
2170 return NULL;
2171 }
2172
2173
2174 //------------------------------Ideal_sign_extended_input----------------------
2175 // Check for useless sign-extension before a partial-word store
2176 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) )
2177 // If (conIL == conIR && conIR <= num_bits) this simplifies to
2178 // (StoreB ... (valIn) )
2179 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) {
2180 Node *val = in(MemNode::ValueIn);
2181 if( val->Opcode() == Op_RShiftI ) {
2182 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2183 if( t && t->is_con() && (t->get_con() <= num_bits) ) {
2184 Node *shl = val->in(1);
2185 if( shl->Opcode() == Op_LShiftI ) {
2186 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int();
2187 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) {
2188 set_req(MemNode::ValueIn, shl->in(1));
2189 return this;
2190 }
2191 }
2192 }
2193 }
2194 return NULL;
2195 }
2196
2197 //------------------------------value_never_loaded-----------------------------------
2198 // Determine whether there are any possible loads of the value stored.
2199 // For simplicity, we actually check if there are any loads from the
2200 // address stored to, not just for loads of the value stored by this node.
2201 //
2202 bool StoreNode::value_never_loaded( PhaseTransform *phase) const {
2203 Node *adr = in(Address);
2204 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
2205 if (adr_oop == NULL)
2206 return false;
2207 if (!adr_oop->is_known_instance_field())
2208 return false; // if not a distinct instance, there may be aliases of the address
2209 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
2210 Node *use = adr->fast_out(i);
2211 int opc = use->Opcode();
2212 if (use->is_Load() || use->is_LoadStore()) {
2213 return false;
2214 }
2215 }
2216 return true;
2217 }
2218
2219 //=============================================================================
2220 //------------------------------Ideal------------------------------------------
2221 // If the store is from an AND mask that leaves the low bits untouched, then
2222 // we can skip the AND operation. If the store is from a sign-extension
2223 // (a left shift, then right shift) we can skip both.
2224 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
2225 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
2226 if( progress != NULL ) return progress;
2227
2228 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
2229 if( progress != NULL ) return progress;
2230
2231 // Finally check the default case
2232 return StoreNode::Ideal(phase, can_reshape);
2233 }
2234
2235 //=============================================================================
2236 //------------------------------Ideal------------------------------------------
2237 // If the store is from an AND mask that leaves the low bits untouched, then
2238 // we can skip the AND operation
2239 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
2240 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
2241 if( progress != NULL ) return progress;
2242
2243 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
2244 if( progress != NULL ) return progress;
2245
2246 // Finally check the default case
2247 return StoreNode::Ideal(phase, can_reshape);
2248 }
2249
2250 //=============================================================================
2251 //------------------------------Identity---------------------------------------
2252 Node *StoreCMNode::Identity( PhaseTransform *phase ) {
2253 // No need to card mark when storing a null ptr
2254 Node* my_store = in(MemNode::OopStore);
2255 if (my_store->is_Store()) {
2256 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) );
2257 if( t1 == TypePtr::NULL_PTR ) {
2258 return in(MemNode::Memory);
2259 }
2260 }
2261 return this;
2262 }
2263
2264 //------------------------------Value-----------------------------------------
2265 const Type *StoreCMNode::Value( PhaseTransform *phase ) const {
2266 // Either input is TOP ==> the result is TOP
2267 const Type *t = phase->type( in(MemNode::Memory) );
2268 if( t == Type::TOP ) return Type::TOP;
2269 t = phase->type( in(MemNode::Address) );
2270 if( t == Type::TOP ) return Type::TOP;
2271 t = phase->type( in(MemNode::ValueIn) );
2272 if( t == Type::TOP ) return Type::TOP;
2273 // If extra input is TOP ==> the result is TOP
2274 t = phase->type( in(MemNode::OopStore) );
2275 if( t == Type::TOP ) return Type::TOP;
2276
2277 return StoreNode::Value( phase );
2278 }
2279
2280
2281 //=============================================================================
2282 //----------------------------------SCMemProjNode------------------------------
2283 const Type * SCMemProjNode::Value( PhaseTransform *phase ) const
2284 {
2285 return bottom_type();
2286 }
2287
2288 //=============================================================================
2289 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : Node(5) {
2290 init_req(MemNode::Control, c );
2291 init_req(MemNode::Memory , mem);
2292 init_req(MemNode::Address, adr);
2293 init_req(MemNode::ValueIn, val);
2294 init_req( ExpectedIn, ex );
2295 init_class_id(Class_LoadStore);
2296
2297 }
2298
2299 //=============================================================================
2300 //-------------------------------adr_type--------------------------------------
2301 // Do we Match on this edge index or not? Do not match memory
2302 const TypePtr* ClearArrayNode::adr_type() const {
2303 Node *adr = in(3);
2304 return MemNode::calculate_adr_type(adr->bottom_type());
2305 }
2306
2307 //------------------------------match_edge-------------------------------------
2308 // Do we Match on this edge index or not? Do not match memory
2309 uint ClearArrayNode::match_edge(uint idx) const {
2310 return idx > 1;
2311 }
2312
2313 //------------------------------Identity---------------------------------------
2314 // Clearing a zero length array does nothing
2315 Node *ClearArrayNode::Identity( PhaseTransform *phase ) {
2316 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
2317 }
2318
2319 //------------------------------Idealize---------------------------------------
2320 // Clearing a short array is faster with stores
2321 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape){
2322 const int unit = BytesPerLong;
2323 const TypeX* t = phase->type(in(2))->isa_intptr_t();
2324 if (!t) return NULL;
2325 if (!t->is_con()) return NULL;
2326 intptr_t raw_count = t->get_con();
2327 intptr_t size = raw_count;
2328 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
2329 // Clearing nothing uses the Identity call.
2330 // Negative clears are possible on dead ClearArrays
2331 // (see jck test stmt114.stmt11402.val).
2332 if (size <= 0 || size % unit != 0) return NULL;
2333 intptr_t count = size / unit;
2334 // Length too long; use fast hardware clear
2335 if (size > Matcher::init_array_short_size) return NULL;
2336 Node *mem = in(1);
2337 if( phase->type(mem)==Type::TOP ) return NULL;
2338 Node *adr = in(3);
2339 const Type* at = phase->type(adr);
2340 if( at==Type::TOP ) return NULL;
2341 const TypePtr* atp = at->isa_ptr();
2342 // adjust atp to be the correct array element address type
2343 if (atp == NULL) atp = TypePtr::BOTTOM;
2344 else atp = atp->add_offset(Type::OffsetBot);
2345 // Get base for derived pointer purposes
2346 if( adr->Opcode() != Op_AddP ) Unimplemented();
2347 Node *base = adr->in(1);
2348
2349 Node *zero = phase->makecon(TypeLong::ZERO);
2350 Node *off = phase->MakeConX(BytesPerLong);
2351 mem = new (phase->C, 4) StoreLNode(in(0),mem,adr,atp,zero);
2352 count--;
2353 while( count-- ) {
2354 mem = phase->transform(mem);
2355 adr = phase->transform(new (phase->C, 4) AddPNode(base,adr,off));
2356 mem = new (phase->C, 4) StoreLNode(in(0),mem,adr,atp,zero);
2357 }
2358 return mem;
2359 }
2360
2361 //----------------------------clear_memory-------------------------------------
2362 // Generate code to initialize object storage to zero.
2363 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2364 intptr_t start_offset,
2365 Node* end_offset,
2366 PhaseGVN* phase) {
2367 Compile* C = phase->C;
2368 intptr_t offset = start_offset;
2369
2370 int unit = BytesPerLong;
2371 if ((offset % unit) != 0) {
2372 Node* adr = new (C, 4) AddPNode(dest, dest, phase->MakeConX(offset));
2373 adr = phase->transform(adr);
2374 const TypePtr* atp = TypeRawPtr::BOTTOM;
2375 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT);
2376 mem = phase->transform(mem);
2377 offset += BytesPerInt;
2378 }
2379 assert((offset % unit) == 0, "");
2380
2381 // Initialize the remaining stuff, if any, with a ClearArray.
2382 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase);
2383 }
2384
2385 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2386 Node* start_offset,
2387 Node* end_offset,
2388 PhaseGVN* phase) {
2389 if (start_offset == end_offset) {
2390 // nothing to do
2391 return mem;
2392 }
2393
2394 Compile* C = phase->C;
2395 int unit = BytesPerLong;
2396 Node* zbase = start_offset;
2397 Node* zend = end_offset;
2398
2399 // Scale to the unit required by the CPU:
2400 if (!Matcher::init_array_count_is_in_bytes) {
2401 Node* shift = phase->intcon(exact_log2(unit));
2402 zbase = phase->transform( new(C,3) URShiftXNode(zbase, shift) );
2403 zend = phase->transform( new(C,3) URShiftXNode(zend, shift) );
2404 }
2405
2406 Node* zsize = phase->transform( new(C,3) SubXNode(zend, zbase) );
2407 Node* zinit = phase->zerocon((unit == BytesPerLong) ? T_LONG : T_INT);
2408
2409 // Bulk clear double-words
2410 Node* adr = phase->transform( new(C,4) AddPNode(dest, dest, start_offset) );
2411 mem = new (C, 4) ClearArrayNode(ctl, mem, zsize, adr);
2412 return phase->transform(mem);
2413 }
2414
2415 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2416 intptr_t start_offset,
2417 intptr_t end_offset,
2418 PhaseGVN* phase) {
2419 if (start_offset == end_offset) {
2420 // nothing to do
2421 return mem;
2422 }
2423
2424 Compile* C = phase->C;
2425 assert((end_offset % BytesPerInt) == 0, "odd end offset");
2426 intptr_t done_offset = end_offset;
2427 if ((done_offset % BytesPerLong) != 0) {
2428 done_offset -= BytesPerInt;
2429 }
2430 if (done_offset > start_offset) {
2431 mem = clear_memory(ctl, mem, dest,
2432 start_offset, phase->MakeConX(done_offset), phase);
2433 }
2434 if (done_offset < end_offset) { // emit the final 32-bit store
2435 Node* adr = new (C, 4) AddPNode(dest, dest, phase->MakeConX(done_offset));
2436 adr = phase->transform(adr);
2437 const TypePtr* atp = TypeRawPtr::BOTTOM;
2438 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT);
2439 mem = phase->transform(mem);
2440 done_offset += BytesPerInt;
2441 }
2442 assert(done_offset == end_offset, "");
2443 return mem;
2444 }
2445
2446 //=============================================================================
2447 // Do we match on this edge? No memory edges
2448 uint StrCompNode::match_edge(uint idx) const {
2449 return idx == 5 || idx == 6;
2450 }
2451
2452 //------------------------------Ideal------------------------------------------
2453 // Return a node which is more "ideal" than the current node. Strip out
2454 // control copies
2455 Node *StrCompNode::Ideal(PhaseGVN *phase, bool can_reshape){
2456 return remove_dead_region(phase, can_reshape) ? this : NULL;
2457 }
2458
2459 //------------------------------Ideal------------------------------------------
2460 // Return a node which is more "ideal" than the current node. Strip out
2461 // control copies
2462 Node *AryEqNode::Ideal(PhaseGVN *phase, bool can_reshape){
2463 return remove_dead_region(phase, can_reshape) ? this : NULL;
2464 }
2465
2466
2467 //=============================================================================
2468 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
2469 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)),
2470 _adr_type(C->get_adr_type(alias_idx))
2471 {
2472 init_class_id(Class_MemBar);
2473 Node* top = C->top();
2474 init_req(TypeFunc::I_O,top);
2475 init_req(TypeFunc::FramePtr,top);
2476 init_req(TypeFunc::ReturnAdr,top);
2477 if (precedent != NULL)
2478 init_req(TypeFunc::Parms, precedent);
2479 }
2480
2481 //------------------------------cmp--------------------------------------------
2482 uint MemBarNode::hash() const { return NO_HASH; }
2483 uint MemBarNode::cmp( const Node &n ) const {
2484 return (&n == this); // Always fail except on self
2485 }
2486
2487 //------------------------------make-------------------------------------------
2488 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
2489 int len = Precedent + (pn == NULL? 0: 1);
2490 switch (opcode) {
2491 case Op_MemBarAcquire: return new(C, len) MemBarAcquireNode(C, atp, pn);
2492 case Op_MemBarRelease: return new(C, len) MemBarReleaseNode(C, atp, pn);
2493 case Op_MemBarVolatile: return new(C, len) MemBarVolatileNode(C, atp, pn);
2494 case Op_MemBarCPUOrder: return new(C, len) MemBarCPUOrderNode(C, atp, pn);
2495 case Op_Initialize: return new(C, len) InitializeNode(C, atp, pn);
2496 default: ShouldNotReachHere(); return NULL;
2497 }
2498 }
2499
2500 //------------------------------Ideal------------------------------------------
2501 // Return a node which is more "ideal" than the current node. Strip out
2502 // control copies
2503 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2504 return remove_dead_region(phase, can_reshape) ? this : NULL;
2505 }
2506
2507 //------------------------------Value------------------------------------------
2508 const Type *MemBarNode::Value( PhaseTransform *phase ) const {
2509 if( !in(0) ) return Type::TOP;
2510 if( phase->type(in(0)) == Type::TOP )
2511 return Type::TOP;
2512 return TypeTuple::MEMBAR;
2513 }
2514
2515 //------------------------------match------------------------------------------
2516 // Construct projections for memory.
2517 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) {
2518 switch (proj->_con) {
2519 case TypeFunc::Control:
2520 case TypeFunc::Memory:
2521 return new (m->C, 1) MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
2522 }
2523 ShouldNotReachHere();
2524 return NULL;
2525 }
2526
2527 //===========================InitializeNode====================================
2528 // SUMMARY:
2529 // This node acts as a memory barrier on raw memory, after some raw stores.
2530 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
2531 // The Initialize can 'capture' suitably constrained stores as raw inits.
2532 // It can coalesce related raw stores into larger units (called 'tiles').
2533 // It can avoid zeroing new storage for memory units which have raw inits.
2534 // At macro-expansion, it is marked 'complete', and does not optimize further.
2535 //
2536 // EXAMPLE:
2537 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
2538 // ctl = incoming control; mem* = incoming memory
2539 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
2540 // First allocate uninitialized memory and fill in the header:
2541 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
2542 // ctl := alloc.Control; mem* := alloc.Memory*
2543 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
2544 // Then initialize to zero the non-header parts of the raw memory block:
2545 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
2546 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
2547 // After the initialize node executes, the object is ready for service:
2548 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
2549 // Suppose its body is immediately initialized as {1,2}:
2550 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
2551 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
2552 // mem.SLICE(#short[*]) := store2
2553 //
2554 // DETAILS:
2555 // An InitializeNode collects and isolates object initialization after
2556 // an AllocateNode and before the next possible safepoint. As a
2557 // memory barrier (MemBarNode), it keeps critical stores from drifting
2558 // down past any safepoint or any publication of the allocation.
2559 // Before this barrier, a newly-allocated object may have uninitialized bits.
2560 // After this barrier, it may be treated as a real oop, and GC is allowed.
2561 //
2562 // The semantics of the InitializeNode include an implicit zeroing of
2563 // the new object from object header to the end of the object.
2564 // (The object header and end are determined by the AllocateNode.)
2565 //
2566 // Certain stores may be added as direct inputs to the InitializeNode.
2567 // These stores must update raw memory, and they must be to addresses
2568 // derived from the raw address produced by AllocateNode, and with
2569 // a constant offset. They must be ordered by increasing offset.
2570 // The first one is at in(RawStores), the last at in(req()-1).
2571 // Unlike most memory operations, they are not linked in a chain,
2572 // but are displayed in parallel as users of the rawmem output of
2573 // the allocation.
2574 //
2575 // (See comments in InitializeNode::capture_store, which continue
2576 // the example given above.)
2577 //
2578 // When the associated Allocate is macro-expanded, the InitializeNode
2579 // may be rewritten to optimize collected stores. A ClearArrayNode
2580 // may also be created at that point to represent any required zeroing.
2581 // The InitializeNode is then marked 'complete', prohibiting further
2582 // capturing of nearby memory operations.
2583 //
2584 // During macro-expansion, all captured initializations which store
2585 // constant values of 32 bits or smaller are coalesced (if advantagous)
2586 // into larger 'tiles' 32 or 64 bits. This allows an object to be
2587 // initialized in fewer memory operations. Memory words which are
2588 // covered by neither tiles nor non-constant stores are pre-zeroed
2589 // by explicit stores of zero. (The code shape happens to do all
2590 // zeroing first, then all other stores, with both sequences occurring
2591 // in order of ascending offsets.)
2592 //
2593 // Alternatively, code may be inserted between an AllocateNode and its
2594 // InitializeNode, to perform arbitrary initialization of the new object.
2595 // E.g., the object copying intrinsics insert complex data transfers here.
2596 // The initialization must then be marked as 'complete' disable the
2597 // built-in zeroing semantics and the collection of initializing stores.
2598 //
2599 // While an InitializeNode is incomplete, reads from the memory state
2600 // produced by it are optimizable if they match the control edge and
2601 // new oop address associated with the allocation/initialization.
2602 // They return a stored value (if the offset matches) or else zero.
2603 // A write to the memory state, if it matches control and address,
2604 // and if it is to a constant offset, may be 'captured' by the
2605 // InitializeNode. It is cloned as a raw memory operation and rewired
2606 // inside the initialization, to the raw oop produced by the allocation.
2607 // Operations on addresses which are provably distinct (e.g., to
2608 // other AllocateNodes) are allowed to bypass the initialization.
2609 //
2610 // The effect of all this is to consolidate object initialization
2611 // (both arrays and non-arrays, both piecewise and bulk) into a
2612 // single location, where it can be optimized as a unit.
2613 //
2614 // Only stores with an offset less than TrackedInitializationLimit words
2615 // will be considered for capture by an InitializeNode. This puts a
2616 // reasonable limit on the complexity of optimized initializations.
2617
2618 //---------------------------InitializeNode------------------------------------
2619 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
2620 : _is_complete(false),
2621 MemBarNode(C, adr_type, rawoop)
2622 {
2623 init_class_id(Class_Initialize);
2624
2625 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
2626 assert(in(RawAddress) == rawoop, "proper init");
2627 // Note: allocation() can be NULL, for secondary initialization barriers
2628 }
2629
2630 // Since this node is not matched, it will be processed by the
2631 // register allocator. Declare that there are no constraints
2632 // on the allocation of the RawAddress edge.
2633 const RegMask &InitializeNode::in_RegMask(uint idx) const {
2634 // This edge should be set to top, by the set_complete. But be conservative.
2635 if (idx == InitializeNode::RawAddress)
2636 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
2637 return RegMask::Empty;
2638 }
2639
2640 Node* InitializeNode::memory(uint alias_idx) {
2641 Node* mem = in(Memory);
2642 if (mem->is_MergeMem()) {
2643 return mem->as_MergeMem()->memory_at(alias_idx);
2644 } else {
2645 // incoming raw memory is not split
2646 return mem;
2647 }
2648 }
2649
2650 bool InitializeNode::is_non_zero() {
2651 if (is_complete()) return false;
2652 remove_extra_zeroes();
2653 return (req() > RawStores);
2654 }
2655
2656 void InitializeNode::set_complete(PhaseGVN* phase) {
2657 assert(!is_complete(), "caller responsibility");
2658 _is_complete = true;
2659
2660 // After this node is complete, it contains a bunch of
2661 // raw-memory initializations. There is no need for
2662 // it to have anything to do with non-raw memory effects.
2663 // Therefore, tell all non-raw users to re-optimize themselves,
2664 // after skipping the memory effects of this initialization.
2665 PhaseIterGVN* igvn = phase->is_IterGVN();
2666 if (igvn) igvn->add_users_to_worklist(this);
2667 }
2668
2669 // convenience function
2670 // return false if the init contains any stores already
2671 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
2672 InitializeNode* init = initialization();
2673 if (init == NULL || init->is_complete()) return false;
2674 init->remove_extra_zeroes();
2675 // for now, if this allocation has already collected any inits, bail:
2676 if (init->is_non_zero()) return false;
2677 init->set_complete(phase);
2678 return true;
2679 }
2680
2681 void InitializeNode::remove_extra_zeroes() {
2682 if (req() == RawStores) return;
2683 Node* zmem = zero_memory();
2684 uint fill = RawStores;
2685 for (uint i = fill; i < req(); i++) {
2686 Node* n = in(i);
2687 if (n->is_top() || n == zmem) continue; // skip
2688 if (fill < i) set_req(fill, n); // compact
2689 ++fill;
2690 }
2691 // delete any empty spaces created:
2692 while (fill < req()) {
2693 del_req(fill);
2694 }
2695 }
2696
2697 // Helper for remembering which stores go with which offsets.
2698 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) {
2699 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
2700 intptr_t offset = -1;
2701 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
2702 phase, offset);
2703 if (base == NULL) return -1; // something is dead,
2704 if (offset < 0) return -1; // dead, dead
2705 return offset;
2706 }
2707
2708 // Helper for proving that an initialization expression is
2709 // "simple enough" to be folded into an object initialization.
2710 // Attempts to prove that a store's initial value 'n' can be captured
2711 // within the initialization without creating a vicious cycle, such as:
2712 // { Foo p = new Foo(); p.next = p; }
2713 // True for constants and parameters and small combinations thereof.
2714 bool InitializeNode::detect_init_independence(Node* n,
2715 bool st_is_pinned,
2716 int& count) {
2717 if (n == NULL) return true; // (can this really happen?)
2718 if (n->is_Proj()) n = n->in(0);
2719 if (n == this) return false; // found a cycle
2720 if (n->is_Con()) return true;
2721 if (n->is_Start()) return true; // params, etc., are OK
2722 if (n->is_Root()) return true; // even better
2723
2724 Node* ctl = n->in(0);
2725 if (ctl != NULL && !ctl->is_top()) {
2726 if (ctl->is_Proj()) ctl = ctl->in(0);
2727 if (ctl == this) return false;
2728
2729 // If we already know that the enclosing memory op is pinned right after
2730 // the init, then any control flow that the store has picked up
2731 // must have preceded the init, or else be equal to the init.
2732 // Even after loop optimizations (which might change control edges)
2733 // a store is never pinned *before* the availability of its inputs.
2734 if (!MemNode::all_controls_dominate(n, this))
2735 return false; // failed to prove a good control
2736
2737 }
2738
2739 // Check data edges for possible dependencies on 'this'.
2740 if ((count += 1) > 20) return false; // complexity limit
2741 for (uint i = 1; i < n->req(); i++) {
2742 Node* m = n->in(i);
2743 if (m == NULL || m == n || m->is_top()) continue;
2744 uint first_i = n->find_edge(m);
2745 if (i != first_i) continue; // process duplicate edge just once
2746 if (!detect_init_independence(m, st_is_pinned, count)) {
2747 return false;
2748 }
2749 }
2750
2751 return true;
2752 }
2753
2754 // Here are all the checks a Store must pass before it can be moved into
2755 // an initialization. Returns zero if a check fails.
2756 // On success, returns the (constant) offset to which the store applies,
2757 // within the initialized memory.
2758 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase) {
2759 const int FAIL = 0;
2760 if (st->req() != MemNode::ValueIn + 1)
2761 return FAIL; // an inscrutable StoreNode (card mark?)
2762 Node* ctl = st->in(MemNode::Control);
2763 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this))
2764 return FAIL; // must be unconditional after the initialization
2765 Node* mem = st->in(MemNode::Memory);
2766 if (!(mem->is_Proj() && mem->in(0) == this))
2767 return FAIL; // must not be preceded by other stores
2768 Node* adr = st->in(MemNode::Address);
2769 intptr_t offset;
2770 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
2771 if (alloc == NULL)
2772 return FAIL; // inscrutable address
2773 if (alloc != allocation())
2774 return FAIL; // wrong allocation! (store needs to float up)
2775 Node* val = st->in(MemNode::ValueIn);
2776 int complexity_count = 0;
2777 if (!detect_init_independence(val, true, complexity_count))
2778 return FAIL; // stored value must be 'simple enough'
2779
2780 return offset; // success
2781 }
2782
2783 // Find the captured store in(i) which corresponds to the range
2784 // [start..start+size) in the initialized object.
2785 // If there is one, return its index i. If there isn't, return the
2786 // negative of the index where it should be inserted.
2787 // Return 0 if the queried range overlaps an initialization boundary
2788 // or if dead code is encountered.
2789 // If size_in_bytes is zero, do not bother with overlap checks.
2790 int InitializeNode::captured_store_insertion_point(intptr_t start,
2791 int size_in_bytes,
2792 PhaseTransform* phase) {
2793 const int FAIL = 0, MAX_STORE = BytesPerLong;
2794
2795 if (is_complete())
2796 return FAIL; // arraycopy got here first; punt
2797
2798 assert(allocation() != NULL, "must be present");
2799
2800 // no negatives, no header fields:
2801 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
2802
2803 // after a certain size, we bail out on tracking all the stores:
2804 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
2805 if (start >= ti_limit) return FAIL;
2806
2807 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
2808 if (i >= limit) return -(int)i; // not found; here is where to put it
2809
2810 Node* st = in(i);
2811 intptr_t st_off = get_store_offset(st, phase);
2812 if (st_off < 0) {
2813 if (st != zero_memory()) {
2814 return FAIL; // bail out if there is dead garbage
2815 }
2816 } else if (st_off > start) {
2817 // ...we are done, since stores are ordered
2818 if (st_off < start + size_in_bytes) {
2819 return FAIL; // the next store overlaps
2820 }
2821 return -(int)i; // not found; here is where to put it
2822 } else if (st_off < start) {
2823 if (size_in_bytes != 0 &&
2824 start < st_off + MAX_STORE &&
2825 start < st_off + st->as_Store()->memory_size()) {
2826 return FAIL; // the previous store overlaps
2827 }
2828 } else {
2829 if (size_in_bytes != 0 &&
2830 st->as_Store()->memory_size() != size_in_bytes) {
2831 return FAIL; // mismatched store size
2832 }
2833 return i;
2834 }
2835
2836 ++i;
2837 }
2838 }
2839
2840 // Look for a captured store which initializes at the offset 'start'
2841 // with the given size. If there is no such store, and no other
2842 // initialization interferes, then return zero_memory (the memory
2843 // projection of the AllocateNode).
2844 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
2845 PhaseTransform* phase) {
2846 assert(stores_are_sane(phase), "");
2847 int i = captured_store_insertion_point(start, size_in_bytes, phase);
2848 if (i == 0) {
2849 return NULL; // something is dead
2850 } else if (i < 0) {
2851 return zero_memory(); // just primordial zero bits here
2852 } else {
2853 Node* st = in(i); // here is the store at this position
2854 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
2855 return st;
2856 }
2857 }
2858
2859 // Create, as a raw pointer, an address within my new object at 'offset'.
2860 Node* InitializeNode::make_raw_address(intptr_t offset,
2861 PhaseTransform* phase) {
2862 Node* addr = in(RawAddress);
2863 if (offset != 0) {
2864 Compile* C = phase->C;
2865 addr = phase->transform( new (C, 4) AddPNode(C->top(), addr,
2866 phase->MakeConX(offset)) );
2867 }
2868 return addr;
2869 }
2870
2871 // Clone the given store, converting it into a raw store
2872 // initializing a field or element of my new object.
2873 // Caller is responsible for retiring the original store,
2874 // with subsume_node or the like.
2875 //
2876 // From the example above InitializeNode::InitializeNode,
2877 // here are the old stores to be captured:
2878 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
2879 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
2880 //
2881 // Here is the changed code; note the extra edges on init:
2882 // alloc = (Allocate ...)
2883 // rawoop = alloc.RawAddress
2884 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
2885 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
2886 // init = (Initialize alloc.Control alloc.Memory rawoop
2887 // rawstore1 rawstore2)
2888 //
2889 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
2890 PhaseTransform* phase) {
2891 assert(stores_are_sane(phase), "");
2892
2893 if (start < 0) return NULL;
2894 assert(can_capture_store(st, phase) == start, "sanity");
2895
2896 Compile* C = phase->C;
2897 int size_in_bytes = st->memory_size();
2898 int i = captured_store_insertion_point(start, size_in_bytes, phase);
2899 if (i == 0) return NULL; // bail out
2900 Node* prev_mem = NULL; // raw memory for the captured store
2901 if (i > 0) {
2902 prev_mem = in(i); // there is a pre-existing store under this one
2903 set_req(i, C->top()); // temporarily disconnect it
2904 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
2905 } else {
2906 i = -i; // no pre-existing store
2907 prev_mem = zero_memory(); // a slice of the newly allocated object
2908 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
2909 set_req(--i, C->top()); // reuse this edge; it has been folded away
2910 else
2911 ins_req(i, C->top()); // build a new edge
2912 }
2913 Node* new_st = st->clone();
2914 new_st->set_req(MemNode::Control, in(Control));
2915 new_st->set_req(MemNode::Memory, prev_mem);
2916 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
2917 new_st = phase->transform(new_st);
2918
2919 // At this point, new_st might have swallowed a pre-existing store
2920 // at the same offset, or perhaps new_st might have disappeared,
2921 // if it redundantly stored the same value (or zero to fresh memory).
2922
2923 // In any case, wire it in:
2924 set_req(i, new_st);
2925
2926 // The caller may now kill the old guy.
2927 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
2928 assert(check_st == new_st || check_st == NULL, "must be findable");
2929 assert(!is_complete(), "");
2930 return new_st;
2931 }
2932
2933 static bool store_constant(jlong* tiles, int num_tiles,
2934 intptr_t st_off, int st_size,
2935 jlong con) {
2936 if ((st_off & (st_size-1)) != 0)
2937 return false; // strange store offset (assume size==2**N)
2938 address addr = (address)tiles + st_off;
2939 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
2940 switch (st_size) {
2941 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
2942 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
2943 case sizeof(jint): *(jint*) addr = (jint) con; break;
2944 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
2945 default: return false; // strange store size (detect size!=2**N here)
2946 }
2947 return true; // return success to caller
2948 }
2949
2950 // Coalesce subword constants into int constants and possibly
2951 // into long constants. The goal, if the CPU permits,
2952 // is to initialize the object with a small number of 64-bit tiles.
2953 // Also, convert floating-point constants to bit patterns.
2954 // Non-constants are not relevant to this pass.
2955 //
2956 // In terms of the running example on InitializeNode::InitializeNode
2957 // and InitializeNode::capture_store, here is the transformation
2958 // of rawstore1 and rawstore2 into rawstore12:
2959 // alloc = (Allocate ...)
2960 // rawoop = alloc.RawAddress
2961 // tile12 = 0x00010002
2962 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
2963 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
2964 //
2965 void
2966 InitializeNode::coalesce_subword_stores(intptr_t header_size,
2967 Node* size_in_bytes,
2968 PhaseGVN* phase) {
2969 Compile* C = phase->C;
2970
2971 assert(stores_are_sane(phase), "");
2972 // Note: After this pass, they are not completely sane,
2973 // since there may be some overlaps.
2974
2975 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
2976
2977 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
2978 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
2979 size_limit = MIN2(size_limit, ti_limit);
2980 size_limit = align_size_up(size_limit, BytesPerLong);
2981 int num_tiles = size_limit / BytesPerLong;
2982
2983 // allocate space for the tile map:
2984 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
2985 jlong tiles_buf[small_len];
2986 Node* nodes_buf[small_len];
2987 jlong inits_buf[small_len];
2988 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
2989 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
2990 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
2991 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
2992 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
2993 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
2994 // tiles: exact bitwise model of all primitive constants
2995 // nodes: last constant-storing node subsumed into the tiles model
2996 // inits: which bytes (in each tile) are touched by any initializations
2997
2998 //// Pass A: Fill in the tile model with any relevant stores.
2999
3000 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
3001 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
3002 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
3003 Node* zmem = zero_memory(); // initially zero memory state
3004 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3005 Node* st = in(i);
3006 intptr_t st_off = get_store_offset(st, phase);
3007
3008 // Figure out the store's offset and constant value:
3009 if (st_off < header_size) continue; //skip (ignore header)
3010 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
3011 int st_size = st->as_Store()->memory_size();
3012 if (st_off + st_size > size_limit) break;
3013
3014 // Record which bytes are touched, whether by constant or not.
3015 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
3016 continue; // skip (strange store size)
3017
3018 const Type* val = phase->type(st->in(MemNode::ValueIn));
3019 if (!val->singleton()) continue; //skip (non-con store)
3020 BasicType type = val->basic_type();
3021
3022 jlong con = 0;
3023 switch (type) {
3024 case T_INT: con = val->is_int()->get_con(); break;
3025 case T_LONG: con = val->is_long()->get_con(); break;
3026 case T_FLOAT: con = jint_cast(val->getf()); break;
3027 case T_DOUBLE: con = jlong_cast(val->getd()); break;
3028 default: continue; //skip (odd store type)
3029 }
3030
3031 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
3032 st->Opcode() == Op_StoreL) {
3033 continue; // This StoreL is already optimal.
3034 }
3035
3036 // Store down the constant.
3037 store_constant(tiles, num_tiles, st_off, st_size, con);
3038
3039 intptr_t j = st_off >> LogBytesPerLong;
3040
3041 if (type == T_INT && st_size == BytesPerInt
3042 && (st_off & BytesPerInt) == BytesPerInt) {
3043 jlong lcon = tiles[j];
3044 if (!Matcher::isSimpleConstant64(lcon) &&
3045 st->Opcode() == Op_StoreI) {
3046 // This StoreI is already optimal by itself.
3047 jint* intcon = (jint*) &tiles[j];
3048 intcon[1] = 0; // undo the store_constant()
3049
3050 // If the previous store is also optimal by itself, back up and
3051 // undo the action of the previous loop iteration... if we can.
3052 // But if we can't, just let the previous half take care of itself.
3053 st = nodes[j];
3054 st_off -= BytesPerInt;
3055 con = intcon[0];
3056 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) {
3057 assert(st_off >= header_size, "still ignoring header");
3058 assert(get_store_offset(st, phase) == st_off, "must be");
3059 assert(in(i-1) == zmem, "must be");
3060 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
3061 assert(con == tcon->is_int()->get_con(), "must be");
3062 // Undo the effects of the previous loop trip, which swallowed st:
3063 intcon[0] = 0; // undo store_constant()
3064 set_req(i-1, st); // undo set_req(i, zmem)
3065 nodes[j] = NULL; // undo nodes[j] = st
3066 --old_subword; // undo ++old_subword
3067 }
3068 continue; // This StoreI is already optimal.
3069 }
3070 }
3071
3072 // This store is not needed.
3073 set_req(i, zmem);
3074 nodes[j] = st; // record for the moment
3075 if (st_size < BytesPerLong) // something has changed
3076 ++old_subword; // includes int/float, but who's counting...
3077 else ++old_long;
3078 }
3079
3080 if ((old_subword + old_long) == 0)
3081 return; // nothing more to do
3082
3083 //// Pass B: Convert any non-zero tiles into optimal constant stores.
3084 // Be sure to insert them before overlapping non-constant stores.
3085 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
3086 for (int j = 0; j < num_tiles; j++) {
3087 jlong con = tiles[j];
3088 jlong init = inits[j];
3089 if (con == 0) continue;
3090 jint con0, con1; // split the constant, address-wise
3091 jint init0, init1; // split the init map, address-wise
3092 { union { jlong con; jint intcon[2]; } u;
3093 u.con = con;
3094 con0 = u.intcon[0];
3095 con1 = u.intcon[1];
3096 u.con = init;
3097 init0 = u.intcon[0];
3098 init1 = u.intcon[1];
3099 }
3100
3101 Node* old = nodes[j];
3102 assert(old != NULL, "need the prior store");
3103 intptr_t offset = (j * BytesPerLong);
3104
3105 bool split = !Matcher::isSimpleConstant64(con);
3106
3107 if (offset < header_size) {
3108 assert(offset + BytesPerInt >= header_size, "second int counts");
3109 assert(*(jint*)&tiles[j] == 0, "junk in header");
3110 split = true; // only the second word counts
3111 // Example: int a[] = { 42 ... }
3112 } else if (con0 == 0 && init0 == -1) {
3113 split = true; // first word is covered by full inits
3114 // Example: int a[] = { ... foo(), 42 ... }
3115 } else if (con1 == 0 && init1 == -1) {
3116 split = true; // second word is covered by full inits
3117 // Example: int a[] = { ... 42, foo() ... }
3118 }
3119
3120 // Here's a case where init0 is neither 0 nor -1:
3121 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
3122 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
3123 // In this case the tile is not split; it is (jlong)42.
3124 // The big tile is stored down, and then the foo() value is inserted.
3125 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
3126
3127 Node* ctl = old->in(MemNode::Control);
3128 Node* adr = make_raw_address(offset, phase);
3129 const TypePtr* atp = TypeRawPtr::BOTTOM;
3130
3131 // One or two coalesced stores to plop down.
3132 Node* st[2];
3133 intptr_t off[2];
3134 int nst = 0;
3135 if (!split) {
3136 ++new_long;
3137 off[nst] = offset;
3138 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3139 phase->longcon(con), T_LONG);
3140 } else {
3141 // Omit either if it is a zero.
3142 if (con0 != 0) {
3143 ++new_int;
3144 off[nst] = offset;
3145 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3146 phase->intcon(con0), T_INT);
3147 }
3148 if (con1 != 0) {
3149 ++new_int;
3150 offset += BytesPerInt;
3151 adr = make_raw_address(offset, phase);
3152 off[nst] = offset;
3153 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3154 phase->intcon(con1), T_INT);
3155 }
3156 }
3157
3158 // Insert second store first, then the first before the second.
3159 // Insert each one just before any overlapping non-constant stores.
3160 while (nst > 0) {
3161 Node* st1 = st[--nst];
3162 C->copy_node_notes_to(st1, old);
3163 st1 = phase->transform(st1);
3164 offset = off[nst];
3165 assert(offset >= header_size, "do not smash header");
3166 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
3167 guarantee(ins_idx != 0, "must re-insert constant store");
3168 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
3169 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
3170 set_req(--ins_idx, st1);
3171 else
3172 ins_req(ins_idx, st1);
3173 }
3174 }
3175
3176 if (PrintCompilation && WizardMode)
3177 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
3178 old_subword, old_long, new_int, new_long);
3179 if (C->log() != NULL)
3180 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
3181 old_subword, old_long, new_int, new_long);
3182
3183 // Clean up any remaining occurrences of zmem:
3184 remove_extra_zeroes();
3185 }
3186
3187 // Explore forward from in(start) to find the first fully initialized
3188 // word, and return its offset. Skip groups of subword stores which
3189 // together initialize full words. If in(start) is itself part of a
3190 // fully initialized word, return the offset of in(start). If there
3191 // are no following full-word stores, or if something is fishy, return
3192 // a negative value.
3193 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
3194 int int_map = 0;
3195 intptr_t int_map_off = 0;
3196 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
3197
3198 for (uint i = start, limit = req(); i < limit; i++) {
3199 Node* st = in(i);
3200
3201 intptr_t st_off = get_store_offset(st, phase);
3202 if (st_off < 0) break; // return conservative answer
3203
3204 int st_size = st->as_Store()->memory_size();
3205 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
3206 return st_off; // we found a complete word init
3207 }
3208
3209 // update the map:
3210
3211 intptr_t this_int_off = align_size_down(st_off, BytesPerInt);
3212 if (this_int_off != int_map_off) {
3213 // reset the map:
3214 int_map = 0;
3215 int_map_off = this_int_off;
3216 }
3217
3218 int subword_off = st_off - this_int_off;
3219 int_map |= right_n_bits(st_size) << subword_off;
3220 if ((int_map & FULL_MAP) == FULL_MAP) {
3221 return this_int_off; // we found a complete word init
3222 }
3223
3224 // Did this store hit or cross the word boundary?
3225 intptr_t next_int_off = align_size_down(st_off + st_size, BytesPerInt);
3226 if (next_int_off == this_int_off + BytesPerInt) {
3227 // We passed the current int, without fully initializing it.
3228 int_map_off = next_int_off;
3229 int_map >>= BytesPerInt;
3230 } else if (next_int_off > this_int_off + BytesPerInt) {
3231 // We passed the current and next int.
3232 return this_int_off + BytesPerInt;
3233 }
3234 }
3235
3236 return -1;
3237 }
3238
3239
3240 // Called when the associated AllocateNode is expanded into CFG.
3241 // At this point, we may perform additional optimizations.
3242 // Linearize the stores by ascending offset, to make memory
3243 // activity as coherent as possible.
3244 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
3245 intptr_t header_size,
3246 Node* size_in_bytes,
3247 PhaseGVN* phase) {
3248 assert(!is_complete(), "not already complete");
3249 assert(stores_are_sane(phase), "");
3250 assert(allocation() != NULL, "must be present");
3251
3252 remove_extra_zeroes();
3253
3254 if (ReduceFieldZeroing || ReduceBulkZeroing)
3255 // reduce instruction count for common initialization patterns
3256 coalesce_subword_stores(header_size, size_in_bytes, phase);
3257
3258 Node* zmem = zero_memory(); // initially zero memory state
3259 Node* inits = zmem; // accumulating a linearized chain of inits
3260 #ifdef ASSERT
3261 intptr_t first_offset = allocation()->minimum_header_size();
3262 intptr_t last_init_off = first_offset; // previous init offset
3263 intptr_t last_init_end = first_offset; // previous init offset+size
3264 intptr_t last_tile_end = first_offset; // previous tile offset+size
3265 #endif
3266 intptr_t zeroes_done = header_size;
3267
3268 bool do_zeroing = true; // we might give up if inits are very sparse
3269 int big_init_gaps = 0; // how many large gaps have we seen?
3270
3271 if (ZeroTLAB) do_zeroing = false;
3272 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
3273
3274 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3275 Node* st = in(i);
3276 intptr_t st_off = get_store_offset(st, phase);
3277 if (st_off < 0)
3278 break; // unknown junk in the inits
3279 if (st->in(MemNode::Memory) != zmem)
3280 break; // complicated store chains somehow in list
3281
3282 int st_size = st->as_Store()->memory_size();
3283 intptr_t next_init_off = st_off + st_size;
3284
3285 if (do_zeroing && zeroes_done < next_init_off) {
3286 // See if this store needs a zero before it or under it.
3287 intptr_t zeroes_needed = st_off;
3288
3289 if (st_size < BytesPerInt) {
3290 // Look for subword stores which only partially initialize words.
3291 // If we find some, we must lay down some word-level zeroes first,
3292 // underneath the subword stores.
3293 //
3294 // Examples:
3295 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
3296 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
3297 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
3298 //
3299 // Note: coalesce_subword_stores may have already done this,
3300 // if it was prompted by constant non-zero subword initializers.
3301 // But this case can still arise with non-constant stores.
3302
3303 intptr_t next_full_store = find_next_fullword_store(i, phase);
3304
3305 // In the examples above:
3306 // in(i) p q r s x y z
3307 // st_off 12 13 14 15 12 13 14
3308 // st_size 1 1 1 1 1 1 1
3309 // next_full_s. 12 16 16 16 16 16 16
3310 // z's_done 12 16 16 16 12 16 12
3311 // z's_needed 12 16 16 16 16 16 16
3312 // zsize 0 0 0 0 4 0 4
3313 if (next_full_store < 0) {
3314 // Conservative tack: Zero to end of current word.
3315 zeroes_needed = align_size_up(zeroes_needed, BytesPerInt);
3316 } else {
3317 // Zero to beginning of next fully initialized word.
3318 // Or, don't zero at all, if we are already in that word.
3319 assert(next_full_store >= zeroes_needed, "must go forward");
3320 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
3321 zeroes_needed = next_full_store;
3322 }
3323 }
3324
3325 if (zeroes_needed > zeroes_done) {
3326 intptr_t zsize = zeroes_needed - zeroes_done;
3327 // Do some incremental zeroing on rawmem, in parallel with inits.
3328 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3329 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3330 zeroes_done, zeroes_needed,
3331 phase);
3332 zeroes_done = zeroes_needed;
3333 if (zsize > Matcher::init_array_short_size && ++big_init_gaps > 2)
3334 do_zeroing = false; // leave the hole, next time
3335 }
3336 }
3337
3338 // Collect the store and move on:
3339 st->set_req(MemNode::Memory, inits);
3340 inits = st; // put it on the linearized chain
3341 set_req(i, zmem); // unhook from previous position
3342
3343 if (zeroes_done == st_off)
3344 zeroes_done = next_init_off;
3345
3346 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
3347
3348 #ifdef ASSERT
3349 // Various order invariants. Weaker than stores_are_sane because
3350 // a large constant tile can be filled in by smaller non-constant stores.
3351 assert(st_off >= last_init_off, "inits do not reverse");
3352 last_init_off = st_off;
3353 const Type* val = NULL;
3354 if (st_size >= BytesPerInt &&
3355 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
3356 (int)val->basic_type() < (int)T_OBJECT) {
3357 assert(st_off >= last_tile_end, "tiles do not overlap");
3358 assert(st_off >= last_init_end, "tiles do not overwrite inits");
3359 last_tile_end = MAX2(last_tile_end, next_init_off);
3360 } else {
3361 intptr_t st_tile_end = align_size_up(next_init_off, BytesPerLong);
3362 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
3363 assert(st_off >= last_init_end, "inits do not overlap");
3364 last_init_end = next_init_off; // it's a non-tile
3365 }
3366 #endif //ASSERT
3367 }
3368
3369 remove_extra_zeroes(); // clear out all the zmems left over
3370 add_req(inits);
3371
3372 if (!ZeroTLAB) {
3373 // If anything remains to be zeroed, zero it all now.
3374 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3375 // if it is the last unused 4 bytes of an instance, forget about it
3376 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
3377 if (zeroes_done + BytesPerLong >= size_limit) {
3378 assert(allocation() != NULL, "");
3379 Node* klass_node = allocation()->in(AllocateNode::KlassNode);
3380 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass();
3381 if (zeroes_done == k->layout_helper())
3382 zeroes_done = size_limit;
3383 }
3384 if (zeroes_done < size_limit) {
3385 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3386 zeroes_done, size_in_bytes, phase);
3387 }
3388 }
3389
3390 set_complete(phase);
3391 return rawmem;
3392 }
3393
3394
3395 #ifdef ASSERT
3396 bool InitializeNode::stores_are_sane(PhaseTransform* phase) {
3397 if (is_complete())
3398 return true; // stores could be anything at this point
3399 assert(allocation() != NULL, "must be present");
3400 intptr_t last_off = allocation()->minimum_header_size();
3401 for (uint i = InitializeNode::RawStores; i < req(); i++) {
3402 Node* st = in(i);
3403 intptr_t st_off = get_store_offset(st, phase);
3404 if (st_off < 0) continue; // ignore dead garbage
3405 if (last_off > st_off) {
3406 tty->print_cr("*** bad store offset at %d: %d > %d", i, last_off, st_off);
3407 this->dump(2);
3408 assert(false, "ascending store offsets");
3409 return false;
3410 }
3411 last_off = st_off + st->as_Store()->memory_size();
3412 }
3413 return true;
3414 }
3415 #endif //ASSERT
3416
3417
3418
3419
3420 //============================MergeMemNode=====================================
3421 //
3422 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
3423 // contributing store or call operations. Each contributor provides the memory
3424 // state for a particular "alias type" (see Compile::alias_type). For example,
3425 // if a MergeMem has an input X for alias category #6, then any memory reference
3426 // to alias category #6 may use X as its memory state input, as an exact equivalent
3427 // to using the MergeMem as a whole.
3428 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
3429 //
3430 // (Here, the <N> notation gives the index of the relevant adr_type.)
3431 //
3432 // In one special case (and more cases in the future), alias categories overlap.
3433 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
3434 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
3435 // it is exactly equivalent to that state W:
3436 // MergeMem(<Bot>: W) <==> W
3437 //
3438 // Usually, the merge has more than one input. In that case, where inputs
3439 // overlap (i.e., one is Bot), the narrower alias type determines the memory
3440 // state for that type, and the wider alias type (Bot) fills in everywhere else:
3441 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
3442 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
3443 //
3444 // A merge can take a "wide" memory state as one of its narrow inputs.
3445 // This simply means that the merge observes out only the relevant parts of
3446 // the wide input. That is, wide memory states arriving at narrow merge inputs
3447 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
3448 //
3449 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
3450 // and that memory slices "leak through":
3451 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
3452 //
3453 // But, in such a cascade, repeated memory slices can "block the leak":
3454 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
3455 //
3456 // In the last example, Y is not part of the combined memory state of the
3457 // outermost MergeMem. The system must, of course, prevent unschedulable
3458 // memory states from arising, so you can be sure that the state Y is somehow
3459 // a precursor to state Y'.
3460 //
3461 //
3462 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
3463 // of each MergeMemNode array are exactly the numerical alias indexes, including
3464 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
3465 // Compile::alias_type (and kin) produce and manage these indexes.
3466 //
3467 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
3468 // (Note that this provides quick access to the top node inside MergeMem methods,
3469 // without the need to reach out via TLS to Compile::current.)
3470 //
3471 // As a consequence of what was just described, a MergeMem that represents a full
3472 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
3473 // containing all alias categories.
3474 //
3475 // MergeMem nodes never (?) have control inputs, so in(0) is NULL.
3476 //
3477 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
3478 // a memory state for the alias type <N>, or else the top node, meaning that
3479 // there is no particular input for that alias type. Note that the length of
3480 // a MergeMem is variable, and may be extended at any time to accommodate new
3481 // memory states at larger alias indexes. When merges grow, they are of course
3482 // filled with "top" in the unused in() positions.
3483 //
3484 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
3485 // (Top was chosen because it works smoothly with passes like GCM.)
3486 //
3487 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
3488 // the type of random VM bits like TLS references.) Since it is always the
3489 // first non-Bot memory slice, some low-level loops use it to initialize an
3490 // index variable: for (i = AliasIdxRaw; i < req(); i++).
3491 //
3492 //
3493 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
3494 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
3495 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
3496 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
3497 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
3498 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
3499 //
3500 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
3501 // really that different from the other memory inputs. An abbreviation called
3502 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
3503 //
3504 //
3505 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
3506 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
3507 // that "emerges though" the base memory will be marked as excluding the alias types
3508 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
3509 //
3510 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
3511 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
3512 //
3513 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
3514 // (It is currently unimplemented.) As you can see, the resulting merge is
3515 // actually a disjoint union of memory states, rather than an overlay.
3516 //
3517
3518 //------------------------------MergeMemNode-----------------------------------
3519 Node* MergeMemNode::make_empty_memory() {
3520 Node* empty_memory = (Node*) Compile::current()->top();
3521 assert(empty_memory->is_top(), "correct sentinel identity");
3522 return empty_memory;
3523 }
3524
3525 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
3526 init_class_id(Class_MergeMem);
3527 // all inputs are nullified in Node::Node(int)
3528 // set_input(0, NULL); // no control input
3529
3530 // Initialize the edges uniformly to top, for starters.
3531 Node* empty_mem = make_empty_memory();
3532 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
3533 init_req(i,empty_mem);
3534 }
3535 assert(empty_memory() == empty_mem, "");
3536
3537 if( new_base != NULL && new_base->is_MergeMem() ) {
3538 MergeMemNode* mdef = new_base->as_MergeMem();
3539 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
3540 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
3541 mms.set_memory(mms.memory2());
3542 }
3543 assert(base_memory() == mdef->base_memory(), "");
3544 } else {
3545 set_base_memory(new_base);
3546 }
3547 }
3548
3549 // Make a new, untransformed MergeMem with the same base as 'mem'.
3550 // If mem is itself a MergeMem, populate the result with the same edges.
3551 MergeMemNode* MergeMemNode::make(Compile* C, Node* mem) {
3552 return new(C, 1+Compile::AliasIdxRaw) MergeMemNode(mem);
3553 }
3554
3555 //------------------------------cmp--------------------------------------------
3556 uint MergeMemNode::hash() const { return NO_HASH; }
3557 uint MergeMemNode::cmp( const Node &n ) const {
3558 return (&n == this); // Always fail except on self
3559 }
3560
3561 //------------------------------Identity---------------------------------------
3562 Node* MergeMemNode::Identity(PhaseTransform *phase) {
3563 // Identity if this merge point does not record any interesting memory
3564 // disambiguations.
3565 Node* base_mem = base_memory();
3566 Node* empty_mem = empty_memory();
3567 if (base_mem != empty_mem) { // Memory path is not dead?
3568 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3569 Node* mem = in(i);
3570 if (mem != empty_mem && mem != base_mem) {
3571 return this; // Many memory splits; no change
3572 }
3573 }
3574 }
3575 return base_mem; // No memory splits; ID on the one true input
3576 }
3577
3578 //------------------------------Ideal------------------------------------------
3579 // This method is invoked recursively on chains of MergeMem nodes
3580 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3581 // Remove chain'd MergeMems
3582 //
3583 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
3584 // relative to the "in(Bot)". Since we are patching both at the same time,
3585 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
3586 // but rewrite each "in(i)" relative to the new "in(Bot)".
3587 Node *progress = NULL;
3588
3589
3590 Node* old_base = base_memory();
3591 Node* empty_mem = empty_memory();
3592 if (old_base == empty_mem)
3593 return NULL; // Dead memory path.
3594
3595 MergeMemNode* old_mbase;
3596 if (old_base != NULL && old_base->is_MergeMem())
3597 old_mbase = old_base->as_MergeMem();
3598 else
3599 old_mbase = NULL;
3600 Node* new_base = old_base;
3601
3602 // simplify stacked MergeMems in base memory
3603 if (old_mbase) new_base = old_mbase->base_memory();
3604
3605 // the base memory might contribute new slices beyond my req()
3606 if (old_mbase) grow_to_match(old_mbase);
3607
3608 // Look carefully at the base node if it is a phi.
3609 PhiNode* phi_base;
3610 if (new_base != NULL && new_base->is_Phi())
3611 phi_base = new_base->as_Phi();
3612 else
3613 phi_base = NULL;
3614
3615 Node* phi_reg = NULL;
3616 uint phi_len = (uint)-1;
3617 if (phi_base != NULL && !phi_base->is_copy()) {
3618 // do not examine phi if degraded to a copy
3619 phi_reg = phi_base->region();
3620 phi_len = phi_base->req();
3621 // see if the phi is unfinished
3622 for (uint i = 1; i < phi_len; i++) {
3623 if (phi_base->in(i) == NULL) {
3624 // incomplete phi; do not look at it yet!
3625 phi_reg = NULL;
3626 phi_len = (uint)-1;
3627 break;
3628 }
3629 }
3630 }
3631
3632 // Note: We do not call verify_sparse on entry, because inputs
3633 // can normalize to the base_memory via subsume_node or similar
3634 // mechanisms. This method repairs that damage.
3635
3636 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
3637
3638 // Look at each slice.
3639 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3640 Node* old_in = in(i);
3641 // calculate the old memory value
3642 Node* old_mem = old_in;
3643 if (old_mem == empty_mem) old_mem = old_base;
3644 assert(old_mem == memory_at(i), "");
3645
3646 // maybe update (reslice) the old memory value
3647
3648 // simplify stacked MergeMems
3649 Node* new_mem = old_mem;
3650 MergeMemNode* old_mmem;
3651 if (old_mem != NULL && old_mem->is_MergeMem())
3652 old_mmem = old_mem->as_MergeMem();
3653 else
3654 old_mmem = NULL;
3655 if (old_mmem == this) {
3656 // This can happen if loops break up and safepoints disappear.
3657 // A merge of BotPtr (default) with a RawPtr memory derived from a
3658 // safepoint can be rewritten to a merge of the same BotPtr with
3659 // the BotPtr phi coming into the loop. If that phi disappears
3660 // also, we can end up with a self-loop of the mergemem.
3661 // In general, if loops degenerate and memory effects disappear,
3662 // a mergemem can be left looking at itself. This simply means
3663 // that the mergemem's default should be used, since there is
3664 // no longer any apparent effect on this slice.
3665 // Note: If a memory slice is a MergeMem cycle, it is unreachable
3666 // from start. Update the input to TOP.
3667 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
3668 }
3669 else if (old_mmem != NULL) {
3670 new_mem = old_mmem->memory_at(i);
3671 }
3672 // else preceeding memory was not a MergeMem
3673
3674 // replace equivalent phis (unfortunately, they do not GVN together)
3675 if (new_mem != NULL && new_mem != new_base &&
3676 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) {
3677 if (new_mem->is_Phi()) {
3678 PhiNode* phi_mem = new_mem->as_Phi();
3679 for (uint i = 1; i < phi_len; i++) {
3680 if (phi_base->in(i) != phi_mem->in(i)) {
3681 phi_mem = NULL;
3682 break;
3683 }
3684 }
3685 if (phi_mem != NULL) {
3686 // equivalent phi nodes; revert to the def
3687 new_mem = new_base;
3688 }
3689 }
3690 }
3691
3692 // maybe store down a new value
3693 Node* new_in = new_mem;
3694 if (new_in == new_base) new_in = empty_mem;
3695
3696 if (new_in != old_in) {
3697 // Warning: Do not combine this "if" with the previous "if"
3698 // A memory slice might have be be rewritten even if it is semantically
3699 // unchanged, if the base_memory value has changed.
3700 set_req(i, new_in);
3701 progress = this; // Report progress
3702 }
3703 }
3704
3705 if (new_base != old_base) {
3706 set_req(Compile::AliasIdxBot, new_base);
3707 // Don't use set_base_memory(new_base), because we need to update du.
3708 assert(base_memory() == new_base, "");
3709 progress = this;
3710 }
3711
3712 if( base_memory() == this ) {
3713 // a self cycle indicates this memory path is dead
3714 set_req(Compile::AliasIdxBot, empty_mem);
3715 }
3716
3717 // Resolve external cycles by calling Ideal on a MergeMem base_memory
3718 // Recursion must occur after the self cycle check above
3719 if( base_memory()->is_MergeMem() ) {
3720 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
3721 Node *m = phase->transform(new_mbase); // Rollup any cycles
3722 if( m != NULL && (m->is_top() ||
3723 m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem) ) {
3724 // propagate rollup of dead cycle to self
3725 set_req(Compile::AliasIdxBot, empty_mem);
3726 }
3727 }
3728
3729 if( base_memory() == empty_mem ) {
3730 progress = this;
3731 // Cut inputs during Parse phase only.
3732 // During Optimize phase a dead MergeMem node will be subsumed by Top.
3733 if( !can_reshape ) {
3734 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3735 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
3736 }
3737 }
3738 }
3739
3740 if( !progress && base_memory()->is_Phi() && can_reshape ) {
3741 // Check if PhiNode::Ideal's "Split phis through memory merges"
3742 // transform should be attempted. Look for this->phi->this cycle.
3743 uint merge_width = req();
3744 if (merge_width > Compile::AliasIdxRaw) {
3745 PhiNode* phi = base_memory()->as_Phi();
3746 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
3747 if (phi->in(i) == this) {
3748 phase->is_IterGVN()->_worklist.push(phi);
3749 break;
3750 }
3751 }
3752 }
3753 }
3754
3755 assert(progress || verify_sparse(), "please, no dups of base");
3756 return progress;
3757 }
3758
3759 //-------------------------set_base_memory-------------------------------------
3760 void MergeMemNode::set_base_memory(Node *new_base) {
3761 Node* empty_mem = empty_memory();
3762 set_req(Compile::AliasIdxBot, new_base);
3763 assert(memory_at(req()) == new_base, "must set default memory");
3764 // Clear out other occurrences of new_base:
3765 if (new_base != empty_mem) {
3766 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3767 if (in(i) == new_base) set_req(i, empty_mem);
3768 }
3769 }
3770 }
3771
3772 //------------------------------out_RegMask------------------------------------
3773 const RegMask &MergeMemNode::out_RegMask() const {
3774 return RegMask::Empty;
3775 }
3776
3777 //------------------------------dump_spec--------------------------------------
3778 #ifndef PRODUCT
3779 void MergeMemNode::dump_spec(outputStream *st) const {
3780 st->print(" {");
3781 Node* base_mem = base_memory();
3782 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
3783 Node* mem = memory_at(i);
3784 if (mem == base_mem) { st->print(" -"); continue; }
3785 st->print( " N%d:", mem->_idx );
3786 Compile::current()->get_adr_type(i)->dump_on(st);
3787 }
3788 st->print(" }");
3789 }
3790 #endif // !PRODUCT
3791
3792
3793 #ifdef ASSERT
3794 static bool might_be_same(Node* a, Node* b) {
3795 if (a == b) return true;
3796 if (!(a->is_Phi() || b->is_Phi())) return false;
3797 // phis shift around during optimization
3798 return true; // pretty stupid...
3799 }
3800
3801 // verify a narrow slice (either incoming or outgoing)
3802 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
3803 if (!VerifyAliases) return; // don't bother to verify unless requested
3804 if (is_error_reported()) return; // muzzle asserts when debugging an error
3805 if (Node::in_dump()) return; // muzzle asserts when printing
3806 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
3807 assert(n != NULL, "");
3808 // Elide intervening MergeMem's
3809 while (n->is_MergeMem()) {
3810 n = n->as_MergeMem()->memory_at(alias_idx);
3811 }
3812 Compile* C = Compile::current();
3813 const TypePtr* n_adr_type = n->adr_type();
3814 if (n == m->empty_memory()) {
3815 // Implicit copy of base_memory()
3816 } else if (n_adr_type != TypePtr::BOTTOM) {
3817 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type");
3818 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
3819 } else {
3820 // A few places like make_runtime_call "know" that VM calls are narrow,
3821 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
3822 bool expected_wide_mem = false;
3823 if (n == m->base_memory()) {
3824 expected_wide_mem = true;
3825 } else if (alias_idx == Compile::AliasIdxRaw ||
3826 n == m->memory_at(Compile::AliasIdxRaw)) {
3827 expected_wide_mem = true;
3828 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
3829 // memory can "leak through" calls on channels that
3830 // are write-once. Allow this also.
3831 expected_wide_mem = true;
3832 }
3833 assert(expected_wide_mem, "expected narrow slice replacement");
3834 }
3835 }
3836 #else // !ASSERT
3837 #define verify_memory_slice(m,i,n) (0) // PRODUCT version is no-op
3838 #endif
3839
3840
3841 //-----------------------------memory_at---------------------------------------
3842 Node* MergeMemNode::memory_at(uint alias_idx) const {
3843 assert(alias_idx >= Compile::AliasIdxRaw ||
3844 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0,
3845 "must avoid base_memory and AliasIdxTop");
3846
3847 // Otherwise, it is a narrow slice.
3848 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
3849 Compile *C = Compile::current();
3850 if (is_empty_memory(n)) {
3851 // the array is sparse; empty slots are the "top" node
3852 n = base_memory();
3853 assert(Node::in_dump()
3854 || n == NULL || n->bottom_type() == Type::TOP
3855 || n->adr_type() == TypePtr::BOTTOM
3856 || n->adr_type() == TypeRawPtr::BOTTOM
3857 || Compile::current()->AliasLevel() == 0,
3858 "must be a wide memory");
3859 // AliasLevel == 0 if we are organizing the memory states manually.
3860 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
3861 } else {
3862 // make sure the stored slice is sane
3863 #ifdef ASSERT
3864 if (is_error_reported() || Node::in_dump()) {
3865 } else if (might_be_same(n, base_memory())) {
3866 // Give it a pass: It is a mostly harmless repetition of the base.
3867 // This can arise normally from node subsumption during optimization.
3868 } else {
3869 verify_memory_slice(this, alias_idx, n);
3870 }
3871 #endif
3872 }
3873 return n;
3874 }
3875
3876 //---------------------------set_memory_at-------------------------------------
3877 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
3878 verify_memory_slice(this, alias_idx, n);
3879 Node* empty_mem = empty_memory();
3880 if (n == base_memory()) n = empty_mem; // collapse default
3881 uint need_req = alias_idx+1;
3882 if (req() < need_req) {
3883 if (n == empty_mem) return; // already the default, so do not grow me
3884 // grow the sparse array
3885 do {
3886 add_req(empty_mem);
3887 } while (req() < need_req);
3888 }
3889 set_req( alias_idx, n );
3890 }
3891
3892
3893
3894 //--------------------------iteration_setup------------------------------------
3895 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
3896 if (other != NULL) {
3897 grow_to_match(other);
3898 // invariant: the finite support of mm2 is within mm->req()
3899 #ifdef ASSERT
3900 for (uint i = req(); i < other->req(); i++) {
3901 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
3902 }
3903 #endif
3904 }
3905 // Replace spurious copies of base_memory by top.
3906 Node* base_mem = base_memory();
3907 if (base_mem != NULL && !base_mem->is_top()) {
3908 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
3909 if (in(i) == base_mem)
3910 set_req(i, empty_memory());
3911 }
3912 }
3913 }
3914
3915 //---------------------------grow_to_match-------------------------------------
3916 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
3917 Node* empty_mem = empty_memory();
3918 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
3919 // look for the finite support of the other memory
3920 for (uint i = other->req(); --i >= req(); ) {
3921 if (other->in(i) != empty_mem) {
3922 uint new_len = i+1;
3923 while (req() < new_len) add_req(empty_mem);
3924 break;
3925 }
3926 }
3927 }
3928
3929 //---------------------------verify_sparse-------------------------------------
3930 #ifndef PRODUCT
3931 bool MergeMemNode::verify_sparse() const {
3932 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
3933 Node* base_mem = base_memory();
3934 // The following can happen in degenerate cases, since empty==top.
3935 if (is_empty_memory(base_mem)) return true;
3936 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3937 assert(in(i) != NULL, "sane slice");
3938 if (in(i) == base_mem) return false; // should have been the sentinel value!
3939 }
3940 return true;
3941 }
3942
3943 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
3944 Node* n;
3945 n = mm->in(idx);
3946 if (mem == n) return true; // might be empty_memory()
3947 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
3948 if (mem == n) return true;
3949 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) {
3950 if (mem == n) return true;
3951 if (n == NULL) break;
3952 }
3953 return false;
3954 }
3955 #endif // !PRODUCT