1 /*
2 * Copyright 1997-2009 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 sentinels
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 sentinels
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 transformed 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: return new (C, 3) LoadUBNode(ctl, mem, adr, adr_type, rt->is_int() );
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 generation 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 bool has_load = ( allocation != NULL &&
1070 (base->in(load_index)->is_Load() ||
1071 base->in(load_index)->is_DecodeN() &&
1072 base->in(load_index)->in(1)->is_Load()) );
1073 if (has_load && 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 base->is_DecodeN() && base->in(1)->is_Load()) {
1111 if (base->is_DecodeN()) {
1112 // Get LoadN node which loads cached Integer object
1113 base = base->in(1);
1114 }
1115 // Eliminate the load of Integer.value for integers from the cache
1116 // array by deriving the value from the index into the array.
1117 // Capture the offset of the load and then reverse the computation.
1118 Node* load_base = base->in(Address)->in(AddPNode::Base);
1119 if (load_base->is_DecodeN()) {
1120 // Get LoadN node which loads IntegerCache.cache field
1121 load_base = load_base->in(1);
1122 }
1123 if (load_base != NULL) {
1124 Compile::AliasType* atp = phase->C->alias_type(load_base->adr_type());
1125 intptr_t cache_offset;
1126 int shift = -1;
1127 Node* cache = NULL;
1128 if (is_autobox_cache(atp)) {
1129 shift = exact_log2(type2aelembytes(T_OBJECT));
1130 cache = AddPNode::Ideal_base_and_offset(load_base->in(Address), phase, cache_offset);
1131 }
1132 if (cache != NULL && base->in(Address)->is_AddP()) {
1133 Node* elements[4];
1134 int count = base->in(Address)->as_AddP()->unpack_offsets(elements, ARRAY_SIZE(elements));
1135 int cache_low;
1136 if (count > 0 && fetch_autobox_base(atp, cache_low)) {
1137 int offset = arrayOopDesc::base_offset_in_bytes(memory_type()) - (cache_low << shift);
1138 // Add up all the offsets making of the address of the load
1139 Node* result = elements[0];
1140 for (int i = 1; i < count; i++) {
1141 result = phase->transform(new (phase->C, 3) AddXNode(result, elements[i]));
1142 }
1143 // Remove the constant offset from the address and then
1144 // remove the scaling of the offset to recover the original index.
1145 result = phase->transform(new (phase->C, 3) AddXNode(result, phase->MakeConX(-offset)));
1146 if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) {
1147 // Peel the shift off directly but wrap it in a dummy node
1148 // since Ideal can't return existing nodes
1149 result = new (phase->C, 3) RShiftXNode(result->in(1), phase->intcon(0));
1150 } else {
1151 result = new (phase->C, 3) RShiftXNode(result, phase->intcon(shift));
1152 }
1153 #ifdef _LP64
1154 result = new (phase->C, 2) ConvL2INode(phase->transform(result));
1155 #endif
1156 return result;
1157 }
1158 }
1159 }
1160 }
1161 return NULL;
1162 }
1163
1164 //------------------------------split_through_phi------------------------------
1165 // Split instance field load through Phi.
1166 Node *LoadNode::split_through_phi(PhaseGVN *phase) {
1167 Node* mem = in(MemNode::Memory);
1168 Node* address = in(MemNode::Address);
1169 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1170 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1171
1172 assert(mem->is_Phi() && (t_oop != NULL) &&
1173 t_oop->is_known_instance_field(), "invalide conditions");
1174
1175 Node *region = mem->in(0);
1176 if (region == NULL) {
1177 return NULL; // Wait stable graph
1178 }
1179 uint cnt = mem->req();
1180 for( uint i = 1; i < cnt; i++ ) {
1181 Node *in = mem->in(i);
1182 if( in == NULL ) {
1183 return NULL; // Wait stable graph
1184 }
1185 }
1186 // Check for loop invariant.
1187 if (cnt == 3) {
1188 for( uint i = 1; i < cnt; i++ ) {
1189 Node *in = mem->in(i);
1190 Node* m = MemNode::optimize_memory_chain(in, addr_t, phase);
1191 if (m == mem) {
1192 set_req(MemNode::Memory, mem->in(cnt - i)); // Skip this phi.
1193 return this;
1194 }
1195 }
1196 }
1197 // Split through Phi (see original code in loopopts.cpp).
1198 assert(phase->C->have_alias_type(addr_t), "instance should have alias type");
1199
1200 // Do nothing here if Identity will find a value
1201 // (to avoid infinite chain of value phis generation).
1202 if ( !phase->eqv(this, this->Identity(phase)) )
1203 return NULL;
1204
1205 // Skip the split if the region dominates some control edge of the address.
1206 if (cnt == 3 && !MemNode::all_controls_dominate(address, region))
1207 return NULL;
1208
1209 const Type* this_type = this->bottom_type();
1210 int this_index = phase->C->get_alias_index(addr_t);
1211 int this_offset = addr_t->offset();
1212 int this_iid = addr_t->is_oopptr()->instance_id();
1213 int wins = 0;
1214 PhaseIterGVN *igvn = phase->is_IterGVN();
1215 Node *phi = new (igvn->C, region->req()) PhiNode(region, this_type, NULL, this_iid, this_index, this_offset);
1216 for( uint i = 1; i < region->req(); i++ ) {
1217 Node *x;
1218 Node* the_clone = NULL;
1219 if( region->in(i) == phase->C->top() ) {
1220 x = phase->C->top(); // Dead path? Use a dead data op
1221 } else {
1222 x = this->clone(); // Else clone up the data op
1223 the_clone = x; // Remember for possible deletion.
1224 // Alter data node to use pre-phi inputs
1225 if( this->in(0) == region ) {
1226 x->set_req( 0, region->in(i) );
1227 } else {
1228 x->set_req( 0, NULL );
1229 }
1230 for( uint j = 1; j < this->req(); j++ ) {
1231 Node *in = this->in(j);
1232 if( in->is_Phi() && in->in(0) == region )
1233 x->set_req( j, in->in(i) ); // Use pre-Phi input for the clone
1234 }
1235 }
1236 // Check for a 'win' on some paths
1237 const Type *t = x->Value(igvn);
1238
1239 bool singleton = t->singleton();
1240
1241 // See comments in PhaseIdealLoop::split_thru_phi().
1242 if( singleton && t == Type::TOP ) {
1243 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1244 }
1245
1246 if( singleton ) {
1247 wins++;
1248 x = igvn->makecon(t);
1249 } else {
1250 // We now call Identity to try to simplify the cloned node.
1251 // Note that some Identity methods call phase->type(this).
1252 // Make sure that the type array is big enough for
1253 // our new node, even though we may throw the node away.
1254 // (This tweaking with igvn only works because x is a new node.)
1255 igvn->set_type(x, t);
1256 // If x is a TypeNode, capture any more-precise type permanently into Node
1257 // otherwise it will be not updated during igvn->transform since
1258 // igvn->type(x) is set to x->Value() already.
1259 x->raise_bottom_type(t);
1260 Node *y = x->Identity(igvn);
1261 if( y != x ) {
1262 wins++;
1263 x = y;
1264 } else {
1265 y = igvn->hash_find(x);
1266 if( y ) {
1267 wins++;
1268 x = y;
1269 } else {
1270 // Else x is a new node we are keeping
1271 // We do not need register_new_node_with_optimizer
1272 // because set_type has already been called.
1273 igvn->_worklist.push(x);
1274 }
1275 }
1276 }
1277 if (x != the_clone && the_clone != NULL)
1278 igvn->remove_dead_node(the_clone);
1279 phi->set_req(i, x);
1280 }
1281 if( wins > 0 ) {
1282 // Record Phi
1283 igvn->register_new_node_with_optimizer(phi);
1284 return phi;
1285 }
1286 igvn->remove_dead_node(phi);
1287 return NULL;
1288 }
1289
1290 //------------------------------Ideal------------------------------------------
1291 // If the load is from Field memory and the pointer is non-null, we can
1292 // zero out the control input.
1293 // If the offset is constant and the base is an object allocation,
1294 // try to hook me up to the exact initializing store.
1295 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1296 Node* p = MemNode::Ideal_common(phase, can_reshape);
1297 if (p) return (p == NodeSentinel) ? NULL : p;
1298
1299 Node* ctrl = in(MemNode::Control);
1300 Node* address = in(MemNode::Address);
1301
1302 // Skip up past a SafePoint control. Cannot do this for Stores because
1303 // pointer stores & cardmarks must stay on the same side of a SafePoint.
1304 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint &&
1305 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw ) {
1306 ctrl = ctrl->in(0);
1307 set_req(MemNode::Control,ctrl);
1308 }
1309
1310 // Check for useless control edge in some common special cases
1311 if (in(MemNode::Control) != NULL) {
1312 intptr_t ignore = 0;
1313 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1314 if (base != NULL
1315 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1316 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw
1317 && all_controls_dominate(base, phase->C->start())) {
1318 // A method-invariant, non-null address (constant or 'this' argument).
1319 set_req(MemNode::Control, NULL);
1320 }
1321 }
1322
1323 if (EliminateAutoBox && can_reshape && in(Address)->is_AddP()) {
1324 Node* base = in(Address)->in(AddPNode::Base);
1325 if (base != NULL) {
1326 Compile::AliasType* atp = phase->C->alias_type(adr_type());
1327 if (is_autobox_object(atp)) {
1328 Node* result = eliminate_autobox(phase);
1329 if (result != NULL) return result;
1330 }
1331 }
1332 }
1333
1334 Node* mem = in(MemNode::Memory);
1335 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1336
1337 if (addr_t != NULL) {
1338 // try to optimize our memory input
1339 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, phase);
1340 if (opt_mem != mem) {
1341 set_req(MemNode::Memory, opt_mem);
1342 if (phase->type( opt_mem ) == Type::TOP) return NULL;
1343 return this;
1344 }
1345 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1346 if (can_reshape && opt_mem->is_Phi() &&
1347 (t_oop != NULL) && t_oop->is_known_instance_field()) {
1348 // Split instance field load through Phi.
1349 Node* result = split_through_phi(phase);
1350 if (result != NULL) return result;
1351 }
1352 }
1353
1354 // Check for prior store with a different base or offset; make Load
1355 // independent. Skip through any number of them. Bail out if the stores
1356 // are in an endless dead cycle and report no progress. This is a key
1357 // transform for Reflection. However, if after skipping through the Stores
1358 // we can't then fold up against a prior store do NOT do the transform as
1359 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
1360 // array memory alive twice: once for the hoisted Load and again after the
1361 // bypassed Store. This situation only works if EVERYBODY who does
1362 // anti-dependence work knows how to bypass. I.e. we need all
1363 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
1364 // the alias index stuff. So instead, peek through Stores and IFF we can
1365 // fold up, do so.
1366 Node* prev_mem = find_previous_store(phase);
1367 // Steps (a), (b): Walk past independent stores to find an exact match.
1368 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) {
1369 // (c) See if we can fold up on the spot, but don't fold up here.
1370 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
1371 // just return a prior value, which is done by Identity calls.
1372 if (can_see_stored_value(prev_mem, phase)) {
1373 // Make ready for step (d):
1374 set_req(MemNode::Memory, prev_mem);
1375 return this;
1376 }
1377 }
1378
1379 return NULL; // No further progress
1380 }
1381
1382 // Helper to recognize certain Klass fields which are invariant across
1383 // some group of array types (e.g., int[] or all T[] where T < Object).
1384 const Type*
1385 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1386 ciKlass* klass) const {
1387 if (tkls->offset() == Klass::modifier_flags_offset_in_bytes() + (int)sizeof(oopDesc)) {
1388 // The field is Klass::_modifier_flags. Return its (constant) value.
1389 // (Folds up the 2nd indirection in aClassConstant.getModifiers().)
1390 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags");
1391 return TypeInt::make(klass->modifier_flags());
1392 }
1393 if (tkls->offset() == Klass::access_flags_offset_in_bytes() + (int)sizeof(oopDesc)) {
1394 // The field is Klass::_access_flags. Return its (constant) value.
1395 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1396 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags");
1397 return TypeInt::make(klass->access_flags());
1398 }
1399 if (tkls->offset() == Klass::layout_helper_offset_in_bytes() + (int)sizeof(oopDesc)) {
1400 // The field is Klass::_layout_helper. Return its constant value if known.
1401 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper");
1402 return TypeInt::make(klass->layout_helper());
1403 }
1404
1405 // No match.
1406 return NULL;
1407 }
1408
1409 //------------------------------Value-----------------------------------------
1410 const Type *LoadNode::Value( PhaseTransform *phase ) const {
1411 // Either input is TOP ==> the result is TOP
1412 Node* mem = in(MemNode::Memory);
1413 const Type *t1 = phase->type(mem);
1414 if (t1 == Type::TOP) return Type::TOP;
1415 Node* adr = in(MemNode::Address);
1416 const TypePtr* tp = phase->type(adr)->isa_ptr();
1417 if (tp == NULL || tp->empty()) return Type::TOP;
1418 int off = tp->offset();
1419 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
1420
1421 // Try to guess loaded type from pointer type
1422 if (tp->base() == Type::AryPtr) {
1423 const Type *t = tp->is_aryptr()->elem();
1424 // Don't do this for integer types. There is only potential profit if
1425 // the element type t is lower than _type; that is, for int types, if _type is
1426 // more restrictive than t. This only happens here if one is short and the other
1427 // char (both 16 bits), and in those cases we've made an intentional decision
1428 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
1429 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
1430 //
1431 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
1432 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
1433 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
1434 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
1435 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
1436 // In fact, that could have been the original type of p1, and p1 could have
1437 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
1438 // expression (LShiftL quux 3) independently optimized to the constant 8.
1439 if ((t->isa_int() == NULL) && (t->isa_long() == NULL)
1440 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
1441 // t might actually be lower than _type, if _type is a unique
1442 // concrete subclass of abstract class t.
1443 // Make sure the reference is not into the header, by comparing
1444 // the offset against the offset of the start of the array's data.
1445 // Different array types begin at slightly different offsets (12 vs. 16).
1446 // We choose T_BYTE as an example base type that is least restrictive
1447 // as to alignment, which will therefore produce the smallest
1448 // possible base offset.
1449 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
1450 if ((uint)off >= (uint)min_base_off) { // is the offset beyond the header?
1451 const Type* jt = t->join(_type);
1452 // In any case, do not allow the join, per se, to empty out the type.
1453 if (jt->empty() && !t->empty()) {
1454 // This can happen if a interface-typed array narrows to a class type.
1455 jt = _type;
1456 }
1457
1458 if (EliminateAutoBox) {
1459 // The pointers in the autobox arrays are always non-null
1460 Node* base = in(Address)->in(AddPNode::Base);
1461 if (base != NULL) {
1462 Compile::AliasType* atp = phase->C->alias_type(base->adr_type());
1463 if (is_autobox_cache(atp)) {
1464 return jt->join(TypePtr::NOTNULL)->is_ptr();
1465 }
1466 }
1467 }
1468 return jt;
1469 }
1470 }
1471 } else if (tp->base() == Type::InstPtr) {
1472 assert( off != Type::OffsetBot ||
1473 // arrays can be cast to Objects
1474 tp->is_oopptr()->klass()->is_java_lang_Object() ||
1475 // unsafe field access may not have a constant offset
1476 phase->C->has_unsafe_access(),
1477 "Field accesses must be precise" );
1478 // For oop loads, we expect the _type to be precise
1479 } else if (tp->base() == Type::KlassPtr) {
1480 assert( off != Type::OffsetBot ||
1481 // arrays can be cast to Objects
1482 tp->is_klassptr()->klass()->is_java_lang_Object() ||
1483 // also allow array-loading from the primary supertype
1484 // array during subtype checks
1485 Opcode() == Op_LoadKlass,
1486 "Field accesses must be precise" );
1487 // For klass/static loads, we expect the _type to be precise
1488 }
1489
1490 const TypeKlassPtr *tkls = tp->isa_klassptr();
1491 if (tkls != NULL && !StressReflectiveCode) {
1492 ciKlass* klass = tkls->klass();
1493 if (klass->is_loaded() && tkls->klass_is_exact()) {
1494 // We are loading a field from a Klass metaobject whose identity
1495 // is known at compile time (the type is "exact" or "precise").
1496 // Check for fields we know are maintained as constants by the VM.
1497 if (tkls->offset() == Klass::super_check_offset_offset_in_bytes() + (int)sizeof(oopDesc)) {
1498 // The field is Klass::_super_check_offset. Return its (constant) value.
1499 // (Folds up type checking code.)
1500 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
1501 return TypeInt::make(klass->super_check_offset());
1502 }
1503 // Compute index into primary_supers array
1504 juint depth = (tkls->offset() - (Klass::primary_supers_offset_in_bytes() + (int)sizeof(oopDesc))) / sizeof(klassOop);
1505 // Check for overflowing; use unsigned compare to handle the negative case.
1506 if( depth < ciKlass::primary_super_limit() ) {
1507 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1508 // (Folds up type checking code.)
1509 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1510 ciKlass *ss = klass->super_of_depth(depth);
1511 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1512 }
1513 const Type* aift = load_array_final_field(tkls, klass);
1514 if (aift != NULL) return aift;
1515 if (tkls->offset() == in_bytes(arrayKlass::component_mirror_offset()) + (int)sizeof(oopDesc)
1516 && klass->is_array_klass()) {
1517 // The field is arrayKlass::_component_mirror. Return its (constant) value.
1518 // (Folds up aClassConstant.getComponentType, common in Arrays.copyOf.)
1519 assert(Opcode() == Op_LoadP, "must load an oop from _component_mirror");
1520 return TypeInstPtr::make(klass->as_array_klass()->component_mirror());
1521 }
1522 if (tkls->offset() == Klass::java_mirror_offset_in_bytes() + (int)sizeof(oopDesc)) {
1523 // The field is Klass::_java_mirror. Return its (constant) value.
1524 // (Folds up the 2nd indirection in anObjConstant.getClass().)
1525 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
1526 return TypeInstPtr::make(klass->java_mirror());
1527 }
1528 }
1529
1530 // We can still check if we are loading from the primary_supers array at a
1531 // shallow enough depth. Even though the klass is not exact, entries less
1532 // than or equal to its super depth are correct.
1533 if (klass->is_loaded() ) {
1534 ciType *inner = klass->klass();
1535 while( inner->is_obj_array_klass() )
1536 inner = inner->as_obj_array_klass()->base_element_type();
1537 if( inner->is_instance_klass() &&
1538 !inner->as_instance_klass()->flags().is_interface() ) {
1539 // Compute index into primary_supers array
1540 juint depth = (tkls->offset() - (Klass::primary_supers_offset_in_bytes() + (int)sizeof(oopDesc))) / sizeof(klassOop);
1541 // Check for overflowing; use unsigned compare to handle the negative case.
1542 if( depth < ciKlass::primary_super_limit() &&
1543 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case
1544 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1545 // (Folds up type checking code.)
1546 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1547 ciKlass *ss = klass->super_of_depth(depth);
1548 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1549 }
1550 }
1551 }
1552
1553 // If the type is enough to determine that the thing is not an array,
1554 // we can give the layout_helper a positive interval type.
1555 // This will help short-circuit some reflective code.
1556 if (tkls->offset() == Klass::layout_helper_offset_in_bytes() + (int)sizeof(oopDesc)
1557 && !klass->is_array_klass() // not directly typed as an array
1558 && !klass->is_interface() // specifically not Serializable & Cloneable
1559 && !klass->is_java_lang_Object() // not the supertype of all T[]
1560 ) {
1561 // Note: When interfaces are reliable, we can narrow the interface
1562 // test to (klass != Serializable && klass != Cloneable).
1563 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
1564 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
1565 // The key property of this type is that it folds up tests
1566 // for array-ness, since it proves that the layout_helper is positive.
1567 // Thus, a generic value like the basic object layout helper works fine.
1568 return TypeInt::make(min_size, max_jint, Type::WidenMin);
1569 }
1570 }
1571
1572 // If we are loading from a freshly-allocated object, produce a zero,
1573 // if the load is provably beyond the header of the object.
1574 // (Also allow a variable load from a fresh array to produce zero.)
1575 if (ReduceFieldZeroing) {
1576 Node* value = can_see_stored_value(mem,phase);
1577 if (value != NULL && value->is_Con())
1578 return value->bottom_type();
1579 }
1580
1581 const TypeOopPtr *tinst = tp->isa_oopptr();
1582 if (tinst != NULL && tinst->is_known_instance_field()) {
1583 // If we have an instance type and our memory input is the
1584 // programs's initial memory state, there is no matching store,
1585 // so just return a zero of the appropriate type
1586 Node *mem = in(MemNode::Memory);
1587 if (mem->is_Parm() && mem->in(0)->is_Start()) {
1588 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
1589 return Type::get_zero_type(_type->basic_type());
1590 }
1591 }
1592 return _type;
1593 }
1594
1595 //------------------------------match_edge-------------------------------------
1596 // Do we Match on this edge index or not? Match only the address.
1597 uint LoadNode::match_edge(uint idx) const {
1598 return idx == MemNode::Address;
1599 }
1600
1601 //--------------------------LoadBNode::Ideal--------------------------------------
1602 //
1603 // If the previous store is to the same address as this load,
1604 // and the value stored was larger than a byte, replace this load
1605 // with the value stored truncated to a byte. If no truncation is
1606 // needed, the replacement is done in LoadNode::Identity().
1607 //
1608 Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1609 Node* mem = in(MemNode::Memory);
1610 Node* value = can_see_stored_value(mem,phase);
1611 if( value && !phase->type(value)->higher_equal( _type ) ) {
1612 Node *result = phase->transform( new (phase->C, 3) LShiftINode(value, phase->intcon(24)) );
1613 return new (phase->C, 3) RShiftINode(result, phase->intcon(24));
1614 }
1615 // Identity call will handle the case where truncation is not needed.
1616 return LoadNode::Ideal(phase, can_reshape);
1617 }
1618
1619 //--------------------------LoadUBNode::Ideal-------------------------------------
1620 //
1621 // If the previous store is to the same address as this load,
1622 // and the value stored was larger than a byte, replace this load
1623 // with the value stored truncated to a byte. If no truncation is
1624 // needed, the replacement is done in LoadNode::Identity().
1625 //
1626 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
1627 Node* mem = in(MemNode::Memory);
1628 Node* value = can_see_stored_value(mem, phase);
1629 if (value && !phase->type(value)->higher_equal(_type))
1630 return new (phase->C, 3) AndINode(value, phase->intcon(0xFF));
1631 // Identity call will handle the case where truncation is not needed.
1632 return LoadNode::Ideal(phase, can_reshape);
1633 }
1634
1635 //--------------------------LoadUSNode::Ideal-------------------------------------
1636 //
1637 // If the previous store is to the same address as this load,
1638 // and the value stored was larger than a char, replace this load
1639 // with the value stored truncated to a char. If no truncation is
1640 // needed, the replacement is done in LoadNode::Identity().
1641 //
1642 Node *LoadUSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1643 Node* mem = in(MemNode::Memory);
1644 Node* value = can_see_stored_value(mem,phase);
1645 if( value && !phase->type(value)->higher_equal( _type ) )
1646 return new (phase->C, 3) AndINode(value,phase->intcon(0xFFFF));
1647 // Identity call will handle the case where truncation is not needed.
1648 return LoadNode::Ideal(phase, can_reshape);
1649 }
1650
1651 //--------------------------LoadSNode::Ideal--------------------------------------
1652 //
1653 // If the previous store is to the same address as this load,
1654 // and the value stored was larger than a short, replace this load
1655 // with the value stored truncated to a short. If no truncation is
1656 // needed, the replacement is done in LoadNode::Identity().
1657 //
1658 Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1659 Node* mem = in(MemNode::Memory);
1660 Node* value = can_see_stored_value(mem,phase);
1661 if( value && !phase->type(value)->higher_equal( _type ) ) {
1662 Node *result = phase->transform( new (phase->C, 3) LShiftINode(value, phase->intcon(16)) );
1663 return new (phase->C, 3) RShiftINode(result, phase->intcon(16));
1664 }
1665 // Identity call will handle the case where truncation is not needed.
1666 return LoadNode::Ideal(phase, can_reshape);
1667 }
1668
1669 //=============================================================================
1670 //----------------------------LoadKlassNode::make------------------------------
1671 // Polymorphic factory method:
1672 Node *LoadKlassNode::make( PhaseGVN& gvn, Node *mem, Node *adr, const TypePtr* at, const TypeKlassPtr *tk ) {
1673 Compile* C = gvn.C;
1674 Node *ctl = NULL;
1675 // sanity check the alias category against the created node type
1676 const TypeOopPtr *adr_type = adr->bottom_type()->isa_oopptr();
1677 assert(adr_type != NULL, "expecting TypeOopPtr");
1678 #ifdef _LP64
1679 if (adr_type->is_ptr_to_narrowoop()) {
1680 Node* load_klass = gvn.transform(new (C, 3) LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowoop()));
1681 return new (C, 2) DecodeNNode(load_klass, load_klass->bottom_type()->make_ptr());
1682 }
1683 #endif
1684 assert(!adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
1685 return new (C, 3) LoadKlassNode(ctl, mem, adr, at, tk);
1686 }
1687
1688 //------------------------------Value------------------------------------------
1689 const Type *LoadKlassNode::Value( PhaseTransform *phase ) const {
1690 return klass_value_common(phase);
1691 }
1692
1693 const Type *LoadNode::klass_value_common( PhaseTransform *phase ) const {
1694 // Either input is TOP ==> the result is TOP
1695 const Type *t1 = phase->type( in(MemNode::Memory) );
1696 if (t1 == Type::TOP) return Type::TOP;
1697 Node *adr = in(MemNode::Address);
1698 const Type *t2 = phase->type( adr );
1699 if (t2 == Type::TOP) return Type::TOP;
1700 const TypePtr *tp = t2->is_ptr();
1701 if (TypePtr::above_centerline(tp->ptr()) ||
1702 tp->ptr() == TypePtr::Null) return Type::TOP;
1703
1704 // Return a more precise klass, if possible
1705 const TypeInstPtr *tinst = tp->isa_instptr();
1706 if (tinst != NULL) {
1707 ciInstanceKlass* ik = tinst->klass()->as_instance_klass();
1708 int offset = tinst->offset();
1709 if (ik == phase->C->env()->Class_klass()
1710 && (offset == java_lang_Class::klass_offset_in_bytes() ||
1711 offset == java_lang_Class::array_klass_offset_in_bytes())) {
1712 // We are loading a special hidden field from a Class mirror object,
1713 // the field which points to the VM's Klass metaobject.
1714 ciType* t = tinst->java_mirror_type();
1715 // java_mirror_type returns non-null for compile-time Class constants.
1716 if (t != NULL) {
1717 // constant oop => constant klass
1718 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
1719 return TypeKlassPtr::make(ciArrayKlass::make(t));
1720 }
1721 if (!t->is_klass()) {
1722 // a primitive Class (e.g., int.class) has NULL for a klass field
1723 return TypePtr::NULL_PTR;
1724 }
1725 // (Folds up the 1st indirection in aClassConstant.getModifiers().)
1726 return TypeKlassPtr::make(t->as_klass());
1727 }
1728 // non-constant mirror, so we can't tell what's going on
1729 }
1730 if( !ik->is_loaded() )
1731 return _type; // Bail out if not loaded
1732 if (offset == oopDesc::klass_offset_in_bytes()) {
1733 if (tinst->klass_is_exact()) {
1734 return TypeKlassPtr::make(ik);
1735 }
1736 // See if we can become precise: no subklasses and no interface
1737 // (Note: We need to support verified interfaces.)
1738 if (!ik->is_interface() && !ik->has_subklass()) {
1739 //assert(!UseExactTypes, "this code should be useless with exact types");
1740 // Add a dependence; if any subclass added we need to recompile
1741 if (!ik->is_final()) {
1742 // %%% should use stronger assert_unique_concrete_subtype instead
1743 phase->C->dependencies()->assert_leaf_type(ik);
1744 }
1745 // Return precise klass
1746 return TypeKlassPtr::make(ik);
1747 }
1748
1749 // Return root of possible klass
1750 return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/);
1751 }
1752 }
1753
1754 // Check for loading klass from an array
1755 const TypeAryPtr *tary = tp->isa_aryptr();
1756 if( tary != NULL ) {
1757 ciKlass *tary_klass = tary->klass();
1758 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP
1759 && tary->offset() == oopDesc::klass_offset_in_bytes()) {
1760 if (tary->klass_is_exact()) {
1761 return TypeKlassPtr::make(tary_klass);
1762 }
1763 ciArrayKlass *ak = tary->klass()->as_array_klass();
1764 // If the klass is an object array, we defer the question to the
1765 // array component klass.
1766 if( ak->is_obj_array_klass() ) {
1767 assert( ak->is_loaded(), "" );
1768 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass();
1769 if( base_k->is_loaded() && base_k->is_instance_klass() ) {
1770 ciInstanceKlass* ik = base_k->as_instance_klass();
1771 // See if we can become precise: no subklasses and no interface
1772 if (!ik->is_interface() && !ik->has_subklass()) {
1773 //assert(!UseExactTypes, "this code should be useless with exact types");
1774 // Add a dependence; if any subclass added we need to recompile
1775 if (!ik->is_final()) {
1776 phase->C->dependencies()->assert_leaf_type(ik);
1777 }
1778 // Return precise array klass
1779 return TypeKlassPtr::make(ak);
1780 }
1781 }
1782 return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/);
1783 } else { // Found a type-array?
1784 //assert(!UseExactTypes, "this code should be useless with exact types");
1785 assert( ak->is_type_array_klass(), "" );
1786 return TypeKlassPtr::make(ak); // These are always precise
1787 }
1788 }
1789 }
1790
1791 // Check for loading klass from an array klass
1792 const TypeKlassPtr *tkls = tp->isa_klassptr();
1793 if (tkls != NULL && !StressReflectiveCode) {
1794 ciKlass* klass = tkls->klass();
1795 if( !klass->is_loaded() )
1796 return _type; // Bail out if not loaded
1797 if( klass->is_obj_array_klass() &&
1798 (uint)tkls->offset() == objArrayKlass::element_klass_offset_in_bytes() + sizeof(oopDesc)) {
1799 ciKlass* elem = klass->as_obj_array_klass()->element_klass();
1800 // // Always returning precise element type is incorrect,
1801 // // e.g., element type could be object and array may contain strings
1802 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
1803
1804 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
1805 // according to the element type's subclassing.
1806 return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/);
1807 }
1808 if( klass->is_instance_klass() && tkls->klass_is_exact() &&
1809 (uint)tkls->offset() == Klass::super_offset_in_bytes() + sizeof(oopDesc)) {
1810 ciKlass* sup = klass->as_instance_klass()->super();
1811 // The field is Klass::_super. Return its (constant) value.
1812 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
1813 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR;
1814 }
1815 }
1816
1817 // Bailout case
1818 return LoadNode::Value(phase);
1819 }
1820
1821 //------------------------------Identity---------------------------------------
1822 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
1823 // Also feed through the klass in Allocate(...klass...)._klass.
1824 Node* LoadKlassNode::Identity( PhaseTransform *phase ) {
1825 return klass_identity_common(phase);
1826 }
1827
1828 Node* LoadNode::klass_identity_common(PhaseTransform *phase ) {
1829 Node* x = LoadNode::Identity(phase);
1830 if (x != this) return x;
1831
1832 // Take apart the address into an oop and and offset.
1833 // Return 'this' if we cannot.
1834 Node* adr = in(MemNode::Address);
1835 intptr_t offset = 0;
1836 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
1837 if (base == NULL) return this;
1838 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
1839 if (toop == NULL) return this;
1840
1841 // We can fetch the klass directly through an AllocateNode.
1842 // This works even if the klass is not constant (clone or newArray).
1843 if (offset == oopDesc::klass_offset_in_bytes()) {
1844 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
1845 if (allocated_klass != NULL) {
1846 return allocated_klass;
1847 }
1848 }
1849
1850 // Simplify k.java_mirror.as_klass to plain k, where k is a klassOop.
1851 // Simplify ak.component_mirror.array_klass to plain ak, ak an arrayKlass.
1852 // See inline_native_Class_query for occurrences of these patterns.
1853 // Java Example: x.getClass().isAssignableFrom(y)
1854 // Java Example: Array.newInstance(x.getClass().getComponentType(), n)
1855 //
1856 // This improves reflective code, often making the Class
1857 // mirror go completely dead. (Current exception: Class
1858 // mirrors may appear in debug info, but we could clean them out by
1859 // introducing a new debug info operator for klassOop.java_mirror).
1860 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass()
1861 && (offset == java_lang_Class::klass_offset_in_bytes() ||
1862 offset == java_lang_Class::array_klass_offset_in_bytes())) {
1863 // We are loading a special hidden field from a Class mirror,
1864 // the field which points to its Klass or arrayKlass metaobject.
1865 if (base->is_Load()) {
1866 Node* adr2 = base->in(MemNode::Address);
1867 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
1868 if (tkls != NULL && !tkls->empty()
1869 && (tkls->klass()->is_instance_klass() ||
1870 tkls->klass()->is_array_klass())
1871 && adr2->is_AddP()
1872 ) {
1873 int mirror_field = Klass::java_mirror_offset_in_bytes();
1874 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
1875 mirror_field = in_bytes(arrayKlass::component_mirror_offset());
1876 }
1877 if (tkls->offset() == mirror_field + (int)sizeof(oopDesc)) {
1878 return adr2->in(AddPNode::Base);
1879 }
1880 }
1881 }
1882 }
1883
1884 return this;
1885 }
1886
1887
1888 //------------------------------Value------------------------------------------
1889 const Type *LoadNKlassNode::Value( PhaseTransform *phase ) const {
1890 const Type *t = klass_value_common(phase);
1891 if (t == Type::TOP)
1892 return t;
1893
1894 return t->make_narrowoop();
1895 }
1896
1897 //------------------------------Identity---------------------------------------
1898 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
1899 // Also feed through the klass in Allocate(...klass...)._klass.
1900 Node* LoadNKlassNode::Identity( PhaseTransform *phase ) {
1901 Node *x = klass_identity_common(phase);
1902
1903 const Type *t = phase->type( x );
1904 if( t == Type::TOP ) return x;
1905 if( t->isa_narrowoop()) return x;
1906
1907 return phase->transform(new (phase->C, 2) EncodePNode(x, t->make_narrowoop()));
1908 }
1909
1910 //------------------------------Value-----------------------------------------
1911 const Type *LoadRangeNode::Value( PhaseTransform *phase ) const {
1912 // Either input is TOP ==> the result is TOP
1913 const Type *t1 = phase->type( in(MemNode::Memory) );
1914 if( t1 == Type::TOP ) return Type::TOP;
1915 Node *adr = in(MemNode::Address);
1916 const Type *t2 = phase->type( adr );
1917 if( t2 == Type::TOP ) return Type::TOP;
1918 const TypePtr *tp = t2->is_ptr();
1919 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
1920 const TypeAryPtr *tap = tp->isa_aryptr();
1921 if( !tap ) return _type;
1922 return tap->size();
1923 }
1924
1925 //-------------------------------Ideal---------------------------------------
1926 // Feed through the length in AllocateArray(...length...)._length.
1927 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1928 Node* p = MemNode::Ideal_common(phase, can_reshape);
1929 if (p) return (p == NodeSentinel) ? NULL : p;
1930
1931 // Take apart the address into an oop and and offset.
1932 // Return 'this' if we cannot.
1933 Node* adr = in(MemNode::Address);
1934 intptr_t offset = 0;
1935 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
1936 if (base == NULL) return NULL;
1937 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
1938 if (tary == NULL) return NULL;
1939
1940 // We can fetch the length directly through an AllocateArrayNode.
1941 // This works even if the length is not constant (clone or newArray).
1942 if (offset == arrayOopDesc::length_offset_in_bytes()) {
1943 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
1944 if (alloc != NULL) {
1945 Node* allocated_length = alloc->Ideal_length();
1946 Node* len = alloc->make_ideal_length(tary, phase);
1947 if (allocated_length != len) {
1948 // New CastII improves on this.
1949 return len;
1950 }
1951 }
1952 }
1953
1954 return NULL;
1955 }
1956
1957 //------------------------------Identity---------------------------------------
1958 // Feed through the length in AllocateArray(...length...)._length.
1959 Node* LoadRangeNode::Identity( PhaseTransform *phase ) {
1960 Node* x = LoadINode::Identity(phase);
1961 if (x != this) return x;
1962
1963 // Take apart the address into an oop and and offset.
1964 // Return 'this' if we cannot.
1965 Node* adr = in(MemNode::Address);
1966 intptr_t offset = 0;
1967 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
1968 if (base == NULL) return this;
1969 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
1970 if (tary == NULL) return this;
1971
1972 // We can fetch the length directly through an AllocateArrayNode.
1973 // This works even if the length is not constant (clone or newArray).
1974 if (offset == arrayOopDesc::length_offset_in_bytes()) {
1975 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
1976 if (alloc != NULL) {
1977 Node* allocated_length = alloc->Ideal_length();
1978 // Do not allow make_ideal_length to allocate a CastII node.
1979 Node* len = alloc->make_ideal_length(tary, phase, false);
1980 if (allocated_length == len) {
1981 // Return allocated_length only if it would not be improved by a CastII.
1982 return allocated_length;
1983 }
1984 }
1985 }
1986
1987 return this;
1988
1989 }
1990
1991 //=============================================================================
1992 //---------------------------StoreNode::make-----------------------------------
1993 // Polymorphic factory method:
1994 StoreNode* StoreNode::make( PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt ) {
1995 Compile* C = gvn.C;
1996
1997 switch (bt) {
1998 case T_BOOLEAN:
1999 case T_BYTE: return new (C, 4) StoreBNode(ctl, mem, adr, adr_type, val);
2000 case T_INT: return new (C, 4) StoreINode(ctl, mem, adr, adr_type, val);
2001 case T_CHAR:
2002 case T_SHORT: return new (C, 4) StoreCNode(ctl, mem, adr, adr_type, val);
2003 case T_LONG: return new (C, 4) StoreLNode(ctl, mem, adr, adr_type, val);
2004 case T_FLOAT: return new (C, 4) StoreFNode(ctl, mem, adr, adr_type, val);
2005 case T_DOUBLE: return new (C, 4) StoreDNode(ctl, mem, adr, adr_type, val);
2006 case T_ADDRESS:
2007 case T_OBJECT:
2008 #ifdef _LP64
2009 if (adr->bottom_type()->is_ptr_to_narrowoop() ||
2010 (UseCompressedOops && val->bottom_type()->isa_klassptr() &&
2011 adr->bottom_type()->isa_rawptr())) {
2012 val = gvn.transform(new (C, 2) EncodePNode(val, val->bottom_type()->make_narrowoop()));
2013 return new (C, 4) StoreNNode(ctl, mem, adr, adr_type, val);
2014 } else
2015 #endif
2016 {
2017 return new (C, 4) StorePNode(ctl, mem, adr, adr_type, val);
2018 }
2019 }
2020 ShouldNotReachHere();
2021 return (StoreNode*)NULL;
2022 }
2023
2024 StoreLNode* StoreLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val) {
2025 bool require_atomic = true;
2026 return new (C, 4) StoreLNode(ctl, mem, adr, adr_type, val, require_atomic);
2027 }
2028
2029
2030 //--------------------------bottom_type----------------------------------------
2031 const Type *StoreNode::bottom_type() const {
2032 return Type::MEMORY;
2033 }
2034
2035 //------------------------------hash-------------------------------------------
2036 uint StoreNode::hash() const {
2037 // unroll addition of interesting fields
2038 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2039
2040 // Since they are not commoned, do not hash them:
2041 return NO_HASH;
2042 }
2043
2044 //------------------------------Ideal------------------------------------------
2045 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
2046 // When a store immediately follows a relevant allocation/initialization,
2047 // try to capture it into the initialization, or hoist it above.
2048 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2049 Node* p = MemNode::Ideal_common(phase, can_reshape);
2050 if (p) return (p == NodeSentinel) ? NULL : p;
2051
2052 Node* mem = in(MemNode::Memory);
2053 Node* address = in(MemNode::Address);
2054
2055 // Back-to-back stores to same address? Fold em up.
2056 // Generally unsafe if I have intervening uses...
2057 if (mem->is_Store() && phase->eqv_uncast(mem->in(MemNode::Address), address)) {
2058 // Looking at a dead closed cycle of memory?
2059 assert(mem != mem->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
2060
2061 assert(Opcode() == mem->Opcode() ||
2062 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw,
2063 "no mismatched stores, except on raw memory");
2064
2065 if (mem->outcnt() == 1 && // check for intervening uses
2066 mem->as_Store()->memory_size() <= this->memory_size()) {
2067 // If anybody other than 'this' uses 'mem', we cannot fold 'mem' away.
2068 // For example, 'mem' might be the final state at a conditional return.
2069 // Or, 'mem' might be used by some node which is live at the same time
2070 // 'this' is live, which might be unschedulable. So, require exactly
2071 // ONE user, the 'this' store, until such time as we clone 'mem' for
2072 // each of 'mem's uses (thus making the exactly-1-user-rule hold true).
2073 if (can_reshape) { // (%%% is this an anachronism?)
2074 set_req_X(MemNode::Memory, mem->in(MemNode::Memory),
2075 phase->is_IterGVN());
2076 } else {
2077 // It's OK to do this in the parser, since DU info is always accurate,
2078 // and the parser always refers to nodes via SafePointNode maps.
2079 set_req(MemNode::Memory, mem->in(MemNode::Memory));
2080 }
2081 return this;
2082 }
2083 }
2084
2085 // Capture an unaliased, unconditional, simple store into an initializer.
2086 // Or, if it is independent of the allocation, hoist it above the allocation.
2087 if (ReduceFieldZeroing && /*can_reshape &&*/
2088 mem->is_Proj() && mem->in(0)->is_Initialize()) {
2089 InitializeNode* init = mem->in(0)->as_Initialize();
2090 intptr_t offset = init->can_capture_store(this, phase);
2091 if (offset > 0) {
2092 Node* moved = init->capture_store(this, offset, phase);
2093 // If the InitializeNode captured me, it made a raw copy of me,
2094 // and I need to disappear.
2095 if (moved != NULL) {
2096 // %%% hack to ensure that Ideal returns a new node:
2097 mem = MergeMemNode::make(phase->C, mem);
2098 return mem; // fold me away
2099 }
2100 }
2101 }
2102
2103 return NULL; // No further progress
2104 }
2105
2106 //------------------------------Value-----------------------------------------
2107 const Type *StoreNode::Value( PhaseTransform *phase ) const {
2108 // Either input is TOP ==> the result is TOP
2109 const Type *t1 = phase->type( in(MemNode::Memory) );
2110 if( t1 == Type::TOP ) return Type::TOP;
2111 const Type *t2 = phase->type( in(MemNode::Address) );
2112 if( t2 == Type::TOP ) return Type::TOP;
2113 const Type *t3 = phase->type( in(MemNode::ValueIn) );
2114 if( t3 == Type::TOP ) return Type::TOP;
2115 return Type::MEMORY;
2116 }
2117
2118 //------------------------------Identity---------------------------------------
2119 // Remove redundant stores:
2120 // Store(m, p, Load(m, p)) changes to m.
2121 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
2122 Node *StoreNode::Identity( PhaseTransform *phase ) {
2123 Node* mem = in(MemNode::Memory);
2124 Node* adr = in(MemNode::Address);
2125 Node* val = in(MemNode::ValueIn);
2126
2127 // Load then Store? Then the Store is useless
2128 if (val->is_Load() &&
2129 phase->eqv_uncast( val->in(MemNode::Address), adr ) &&
2130 phase->eqv_uncast( val->in(MemNode::Memory ), mem ) &&
2131 val->as_Load()->store_Opcode() == Opcode()) {
2132 return mem;
2133 }
2134
2135 // Two stores in a row of the same value?
2136 if (mem->is_Store() &&
2137 phase->eqv_uncast( mem->in(MemNode::Address), adr ) &&
2138 phase->eqv_uncast( mem->in(MemNode::ValueIn), val ) &&
2139 mem->Opcode() == Opcode()) {
2140 return mem;
2141 }
2142
2143 // Store of zero anywhere into a freshly-allocated object?
2144 // Then the store is useless.
2145 // (It must already have been captured by the InitializeNode.)
2146 if (ReduceFieldZeroing && phase->type(val)->is_zero_type()) {
2147 // a newly allocated object is already all-zeroes everywhere
2148 if (mem->is_Proj() && mem->in(0)->is_Allocate()) {
2149 return mem;
2150 }
2151
2152 // the store may also apply to zero-bits in an earlier object
2153 Node* prev_mem = find_previous_store(phase);
2154 // Steps (a), (b): Walk past independent stores to find an exact match.
2155 if (prev_mem != NULL) {
2156 Node* prev_val = can_see_stored_value(prev_mem, phase);
2157 if (prev_val != NULL && phase->eqv(prev_val, val)) {
2158 // prev_val and val might differ by a cast; it would be good
2159 // to keep the more informative of the two.
2160 return mem;
2161 }
2162 }
2163 }
2164
2165 return this;
2166 }
2167
2168 //------------------------------match_edge-------------------------------------
2169 // Do we Match on this edge index or not? Match only memory & value
2170 uint StoreNode::match_edge(uint idx) const {
2171 return idx == MemNode::Address || idx == MemNode::ValueIn;
2172 }
2173
2174 //------------------------------cmp--------------------------------------------
2175 // Do not common stores up together. They generally have to be split
2176 // back up anyways, so do not bother.
2177 uint StoreNode::cmp( const Node &n ) const {
2178 return (&n == this); // Always fail except on self
2179 }
2180
2181 //------------------------------Ideal_masked_input-----------------------------
2182 // Check for a useless mask before a partial-word store
2183 // (StoreB ... (AndI valIn conIa) )
2184 // If (conIa & mask == mask) this simplifies to
2185 // (StoreB ... (valIn) )
2186 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
2187 Node *val = in(MemNode::ValueIn);
2188 if( val->Opcode() == Op_AndI ) {
2189 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2190 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
2191 set_req(MemNode::ValueIn, val->in(1));
2192 return this;
2193 }
2194 }
2195 return NULL;
2196 }
2197
2198
2199 //------------------------------Ideal_sign_extended_input----------------------
2200 // Check for useless sign-extension before a partial-word store
2201 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) )
2202 // If (conIL == conIR && conIR <= num_bits) this simplifies to
2203 // (StoreB ... (valIn) )
2204 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) {
2205 Node *val = in(MemNode::ValueIn);
2206 if( val->Opcode() == Op_RShiftI ) {
2207 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2208 if( t && t->is_con() && (t->get_con() <= num_bits) ) {
2209 Node *shl = val->in(1);
2210 if( shl->Opcode() == Op_LShiftI ) {
2211 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int();
2212 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) {
2213 set_req(MemNode::ValueIn, shl->in(1));
2214 return this;
2215 }
2216 }
2217 }
2218 }
2219 return NULL;
2220 }
2221
2222 //------------------------------value_never_loaded-----------------------------------
2223 // Determine whether there are any possible loads of the value stored.
2224 // For simplicity, we actually check if there are any loads from the
2225 // address stored to, not just for loads of the value stored by this node.
2226 //
2227 bool StoreNode::value_never_loaded( PhaseTransform *phase) const {
2228 Node *adr = in(Address);
2229 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
2230 if (adr_oop == NULL)
2231 return false;
2232 if (!adr_oop->is_known_instance_field())
2233 return false; // if not a distinct instance, there may be aliases of the address
2234 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
2235 Node *use = adr->fast_out(i);
2236 int opc = use->Opcode();
2237 if (use->is_Load() || use->is_LoadStore()) {
2238 return false;
2239 }
2240 }
2241 return true;
2242 }
2243
2244 //=============================================================================
2245 //------------------------------Ideal------------------------------------------
2246 // If the store is from an AND mask that leaves the low bits untouched, then
2247 // we can skip the AND operation. If the store is from a sign-extension
2248 // (a left shift, then right shift) we can skip both.
2249 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
2250 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
2251 if( progress != NULL ) return progress;
2252
2253 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
2254 if( progress != NULL ) return progress;
2255
2256 // Finally check the default case
2257 return StoreNode::Ideal(phase, can_reshape);
2258 }
2259
2260 //=============================================================================
2261 //------------------------------Ideal------------------------------------------
2262 // If the store is from an AND mask that leaves the low bits untouched, then
2263 // we can skip the AND operation
2264 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
2265 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
2266 if( progress != NULL ) return progress;
2267
2268 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
2269 if( progress != NULL ) return progress;
2270
2271 // Finally check the default case
2272 return StoreNode::Ideal(phase, can_reshape);
2273 }
2274
2275 //=============================================================================
2276 //------------------------------Identity---------------------------------------
2277 Node *StoreCMNode::Identity( PhaseTransform *phase ) {
2278 // No need to card mark when storing a null ptr
2279 Node* my_store = in(MemNode::OopStore);
2280 if (my_store->is_Store()) {
2281 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) );
2282 if( t1 == TypePtr::NULL_PTR ) {
2283 return in(MemNode::Memory);
2284 }
2285 }
2286 return this;
2287 }
2288
2289 //------------------------------Value-----------------------------------------
2290 const Type *StoreCMNode::Value( PhaseTransform *phase ) const {
2291 // Either input is TOP ==> the result is TOP
2292 const Type *t = phase->type( in(MemNode::Memory) );
2293 if( t == Type::TOP ) return Type::TOP;
2294 t = phase->type( in(MemNode::Address) );
2295 if( t == Type::TOP ) return Type::TOP;
2296 t = phase->type( in(MemNode::ValueIn) );
2297 if( t == Type::TOP ) return Type::TOP;
2298 // If extra input is TOP ==> the result is TOP
2299 t = phase->type( in(MemNode::OopStore) );
2300 if( t == Type::TOP ) return Type::TOP;
2301
2302 return StoreNode::Value( phase );
2303 }
2304
2305
2306 //=============================================================================
2307 //----------------------------------SCMemProjNode------------------------------
2308 const Type * SCMemProjNode::Value( PhaseTransform *phase ) const
2309 {
2310 return bottom_type();
2311 }
2312
2313 //=============================================================================
2314 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : Node(5) {
2315 init_req(MemNode::Control, c );
2316 init_req(MemNode::Memory , mem);
2317 init_req(MemNode::Address, adr);
2318 init_req(MemNode::ValueIn, val);
2319 init_req( ExpectedIn, ex );
2320 init_class_id(Class_LoadStore);
2321
2322 }
2323
2324 //=============================================================================
2325 //-------------------------------adr_type--------------------------------------
2326 // Do we Match on this edge index or not? Do not match memory
2327 const TypePtr* ClearArrayNode::adr_type() const {
2328 Node *adr = in(3);
2329 return MemNode::calculate_adr_type(adr->bottom_type());
2330 }
2331
2332 //------------------------------match_edge-------------------------------------
2333 // Do we Match on this edge index or not? Do not match memory
2334 uint ClearArrayNode::match_edge(uint idx) const {
2335 return idx > 1;
2336 }
2337
2338 //------------------------------Identity---------------------------------------
2339 // Clearing a zero length array does nothing
2340 Node *ClearArrayNode::Identity( PhaseTransform *phase ) {
2341 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
2342 }
2343
2344 //------------------------------Idealize---------------------------------------
2345 // Clearing a short array is faster with stores
2346 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape){
2347 const int unit = BytesPerLong;
2348 const TypeX* t = phase->type(in(2))->isa_intptr_t();
2349 if (!t) return NULL;
2350 if (!t->is_con()) return NULL;
2351 intptr_t raw_count = t->get_con();
2352 intptr_t size = raw_count;
2353 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
2354 // Clearing nothing uses the Identity call.
2355 // Negative clears are possible on dead ClearArrays
2356 // (see jck test stmt114.stmt11402.val).
2357 if (size <= 0 || size % unit != 0) return NULL;
2358 intptr_t count = size / unit;
2359 // Length too long; use fast hardware clear
2360 if (size > Matcher::init_array_short_size) return NULL;
2361 Node *mem = in(1);
2362 if( phase->type(mem)==Type::TOP ) return NULL;
2363 Node *adr = in(3);
2364 const Type* at = phase->type(adr);
2365 if( at==Type::TOP ) return NULL;
2366 const TypePtr* atp = at->isa_ptr();
2367 // adjust atp to be the correct array element address type
2368 if (atp == NULL) atp = TypePtr::BOTTOM;
2369 else atp = atp->add_offset(Type::OffsetBot);
2370 // Get base for derived pointer purposes
2371 if( adr->Opcode() != Op_AddP ) Unimplemented();
2372 Node *base = adr->in(1);
2373
2374 Node *zero = phase->makecon(TypeLong::ZERO);
2375 Node *off = phase->MakeConX(BytesPerLong);
2376 mem = new (phase->C, 4) StoreLNode(in(0),mem,adr,atp,zero);
2377 count--;
2378 while( count-- ) {
2379 mem = phase->transform(mem);
2380 adr = phase->transform(new (phase->C, 4) AddPNode(base,adr,off));
2381 mem = new (phase->C, 4) StoreLNode(in(0),mem,adr,atp,zero);
2382 }
2383 return mem;
2384 }
2385
2386 //----------------------------clear_memory-------------------------------------
2387 // Generate code to initialize object storage to zero.
2388 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2389 intptr_t start_offset,
2390 Node* end_offset,
2391 PhaseGVN* phase) {
2392 Compile* C = phase->C;
2393 intptr_t offset = start_offset;
2394
2395 int unit = BytesPerLong;
2396 if ((offset % unit) != 0) {
2397 Node* adr = new (C, 4) AddPNode(dest, dest, phase->MakeConX(offset));
2398 adr = phase->transform(adr);
2399 const TypePtr* atp = TypeRawPtr::BOTTOM;
2400 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT);
2401 mem = phase->transform(mem);
2402 offset += BytesPerInt;
2403 }
2404 assert((offset % unit) == 0, "");
2405
2406 // Initialize the remaining stuff, if any, with a ClearArray.
2407 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase);
2408 }
2409
2410 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2411 Node* start_offset,
2412 Node* end_offset,
2413 PhaseGVN* phase) {
2414 if (start_offset == end_offset) {
2415 // nothing to do
2416 return mem;
2417 }
2418
2419 Compile* C = phase->C;
2420 int unit = BytesPerLong;
2421 Node* zbase = start_offset;
2422 Node* zend = end_offset;
2423
2424 // Scale to the unit required by the CPU:
2425 if (!Matcher::init_array_count_is_in_bytes) {
2426 Node* shift = phase->intcon(exact_log2(unit));
2427 zbase = phase->transform( new(C,3) URShiftXNode(zbase, shift) );
2428 zend = phase->transform( new(C,3) URShiftXNode(zend, shift) );
2429 }
2430
2431 Node* zsize = phase->transform( new(C,3) SubXNode(zend, zbase) );
2432 Node* zinit = phase->zerocon((unit == BytesPerLong) ? T_LONG : T_INT);
2433
2434 // Bulk clear double-words
2435 Node* adr = phase->transform( new(C,4) AddPNode(dest, dest, start_offset) );
2436 mem = new (C, 4) ClearArrayNode(ctl, mem, zsize, adr);
2437 return phase->transform(mem);
2438 }
2439
2440 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2441 intptr_t start_offset,
2442 intptr_t end_offset,
2443 PhaseGVN* phase) {
2444 if (start_offset == end_offset) {
2445 // nothing to do
2446 return mem;
2447 }
2448
2449 Compile* C = phase->C;
2450 assert((end_offset % BytesPerInt) == 0, "odd end offset");
2451 intptr_t done_offset = end_offset;
2452 if ((done_offset % BytesPerLong) != 0) {
2453 done_offset -= BytesPerInt;
2454 }
2455 if (done_offset > start_offset) {
2456 mem = clear_memory(ctl, mem, dest,
2457 start_offset, phase->MakeConX(done_offset), phase);
2458 }
2459 if (done_offset < end_offset) { // emit the final 32-bit store
2460 Node* adr = new (C, 4) AddPNode(dest, dest, phase->MakeConX(done_offset));
2461 adr = phase->transform(adr);
2462 const TypePtr* atp = TypeRawPtr::BOTTOM;
2463 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT);
2464 mem = phase->transform(mem);
2465 done_offset += BytesPerInt;
2466 }
2467 assert(done_offset == end_offset, "");
2468 return mem;
2469 }
2470
2471 //=============================================================================
2472 // Do we match on this edge? No memory edges
2473 uint StrCompNode::match_edge(uint idx) const {
2474 return idx == 5 || idx == 6;
2475 }
2476
2477 //------------------------------Ideal------------------------------------------
2478 // Return a node which is more "ideal" than the current node. Strip out
2479 // control copies
2480 Node *StrCompNode::Ideal(PhaseGVN *phase, bool can_reshape){
2481 return remove_dead_region(phase, can_reshape) ? this : NULL;
2482 }
2483
2484 // Do we match on this edge? No memory edges
2485 uint StrEqualsNode::match_edge(uint idx) const {
2486 return idx == 5 || idx == 6;
2487 }
2488
2489 //------------------------------Ideal------------------------------------------
2490 // Return a node which is more "ideal" than the current node. Strip out
2491 // control copies
2492 Node *StrEqualsNode::Ideal(PhaseGVN *phase, bool can_reshape){
2493 return remove_dead_region(phase, can_reshape) ? this : NULL;
2494 }
2495
2496 //=============================================================================
2497 // Do we match on this edge? No memory edges
2498 uint StrIndexOfNode::match_edge(uint idx) const {
2499 return idx == 5 || idx == 6;
2500 }
2501
2502 //------------------------------Ideal------------------------------------------
2503 // Return a node which is more "ideal" than the current node. Strip out
2504 // control copies
2505 Node *StrIndexOfNode::Ideal(PhaseGVN *phase, bool can_reshape){
2506 return remove_dead_region(phase, can_reshape) ? this : NULL;
2507 }
2508
2509 //------------------------------Ideal------------------------------------------
2510 // Return a node which is more "ideal" than the current node. Strip out
2511 // control copies
2512 Node *AryEqNode::Ideal(PhaseGVN *phase, bool can_reshape){
2513 return remove_dead_region(phase, can_reshape) ? this : NULL;
2514 }
2515
2516 //=============================================================================
2517 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
2518 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)),
2519 _adr_type(C->get_adr_type(alias_idx))
2520 {
2521 init_class_id(Class_MemBar);
2522 Node* top = C->top();
2523 init_req(TypeFunc::I_O,top);
2524 init_req(TypeFunc::FramePtr,top);
2525 init_req(TypeFunc::ReturnAdr,top);
2526 if (precedent != NULL)
2527 init_req(TypeFunc::Parms, precedent);
2528 }
2529
2530 //------------------------------cmp--------------------------------------------
2531 uint MemBarNode::hash() const { return NO_HASH; }
2532 uint MemBarNode::cmp( const Node &n ) const {
2533 return (&n == this); // Always fail except on self
2534 }
2535
2536 //------------------------------make-------------------------------------------
2537 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
2538 int len = Precedent + (pn == NULL? 0: 1);
2539 switch (opcode) {
2540 case Op_MemBarAcquire: return new(C, len) MemBarAcquireNode(C, atp, pn);
2541 case Op_MemBarRelease: return new(C, len) MemBarReleaseNode(C, atp, pn);
2542 case Op_MemBarVolatile: return new(C, len) MemBarVolatileNode(C, atp, pn);
2543 case Op_MemBarCPUOrder: return new(C, len) MemBarCPUOrderNode(C, atp, pn);
2544 case Op_Initialize: return new(C, len) InitializeNode(C, atp, pn);
2545 default: ShouldNotReachHere(); return NULL;
2546 }
2547 }
2548
2549 //------------------------------Ideal------------------------------------------
2550 // Return a node which is more "ideal" than the current node. Strip out
2551 // control copies
2552 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2553 return remove_dead_region(phase, can_reshape) ? this : NULL;
2554 }
2555
2556 //------------------------------Value------------------------------------------
2557 const Type *MemBarNode::Value( PhaseTransform *phase ) const {
2558 if( !in(0) ) return Type::TOP;
2559 if( phase->type(in(0)) == Type::TOP )
2560 return Type::TOP;
2561 return TypeTuple::MEMBAR;
2562 }
2563
2564 //------------------------------match------------------------------------------
2565 // Construct projections for memory.
2566 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) {
2567 switch (proj->_con) {
2568 case TypeFunc::Control:
2569 case TypeFunc::Memory:
2570 return new (m->C, 1) MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
2571 }
2572 ShouldNotReachHere();
2573 return NULL;
2574 }
2575
2576 //===========================InitializeNode====================================
2577 // SUMMARY:
2578 // This node acts as a memory barrier on raw memory, after some raw stores.
2579 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
2580 // The Initialize can 'capture' suitably constrained stores as raw inits.
2581 // It can coalesce related raw stores into larger units (called 'tiles').
2582 // It can avoid zeroing new storage for memory units which have raw inits.
2583 // At macro-expansion, it is marked 'complete', and does not optimize further.
2584 //
2585 // EXAMPLE:
2586 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
2587 // ctl = incoming control; mem* = incoming memory
2588 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
2589 // First allocate uninitialized memory and fill in the header:
2590 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
2591 // ctl := alloc.Control; mem* := alloc.Memory*
2592 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
2593 // Then initialize to zero the non-header parts of the raw memory block:
2594 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
2595 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
2596 // After the initialize node executes, the object is ready for service:
2597 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
2598 // Suppose its body is immediately initialized as {1,2}:
2599 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
2600 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
2601 // mem.SLICE(#short[*]) := store2
2602 //
2603 // DETAILS:
2604 // An InitializeNode collects and isolates object initialization after
2605 // an AllocateNode and before the next possible safepoint. As a
2606 // memory barrier (MemBarNode), it keeps critical stores from drifting
2607 // down past any safepoint or any publication of the allocation.
2608 // Before this barrier, a newly-allocated object may have uninitialized bits.
2609 // After this barrier, it may be treated as a real oop, and GC is allowed.
2610 //
2611 // The semantics of the InitializeNode include an implicit zeroing of
2612 // the new object from object header to the end of the object.
2613 // (The object header and end are determined by the AllocateNode.)
2614 //
2615 // Certain stores may be added as direct inputs to the InitializeNode.
2616 // These stores must update raw memory, and they must be to addresses
2617 // derived from the raw address produced by AllocateNode, and with
2618 // a constant offset. They must be ordered by increasing offset.
2619 // The first one is at in(RawStores), the last at in(req()-1).
2620 // Unlike most memory operations, they are not linked in a chain,
2621 // but are displayed in parallel as users of the rawmem output of
2622 // the allocation.
2623 //
2624 // (See comments in InitializeNode::capture_store, which continue
2625 // the example given above.)
2626 //
2627 // When the associated Allocate is macro-expanded, the InitializeNode
2628 // may be rewritten to optimize collected stores. A ClearArrayNode
2629 // may also be created at that point to represent any required zeroing.
2630 // The InitializeNode is then marked 'complete', prohibiting further
2631 // capturing of nearby memory operations.
2632 //
2633 // During macro-expansion, all captured initializations which store
2634 // constant values of 32 bits or smaller are coalesced (if advantageous)
2635 // into larger 'tiles' 32 or 64 bits. This allows an object to be
2636 // initialized in fewer memory operations. Memory words which are
2637 // covered by neither tiles nor non-constant stores are pre-zeroed
2638 // by explicit stores of zero. (The code shape happens to do all
2639 // zeroing first, then all other stores, with both sequences occurring
2640 // in order of ascending offsets.)
2641 //
2642 // Alternatively, code may be inserted between an AllocateNode and its
2643 // InitializeNode, to perform arbitrary initialization of the new object.
2644 // E.g., the object copying intrinsics insert complex data transfers here.
2645 // The initialization must then be marked as 'complete' disable the
2646 // built-in zeroing semantics and the collection of initializing stores.
2647 //
2648 // While an InitializeNode is incomplete, reads from the memory state
2649 // produced by it are optimizable if they match the control edge and
2650 // new oop address associated with the allocation/initialization.
2651 // They return a stored value (if the offset matches) or else zero.
2652 // A write to the memory state, if it matches control and address,
2653 // and if it is to a constant offset, may be 'captured' by the
2654 // InitializeNode. It is cloned as a raw memory operation and rewired
2655 // inside the initialization, to the raw oop produced by the allocation.
2656 // Operations on addresses which are provably distinct (e.g., to
2657 // other AllocateNodes) are allowed to bypass the initialization.
2658 //
2659 // The effect of all this is to consolidate object initialization
2660 // (both arrays and non-arrays, both piecewise and bulk) into a
2661 // single location, where it can be optimized as a unit.
2662 //
2663 // Only stores with an offset less than TrackedInitializationLimit words
2664 // will be considered for capture by an InitializeNode. This puts a
2665 // reasonable limit on the complexity of optimized initializations.
2666
2667 //---------------------------InitializeNode------------------------------------
2668 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
2669 : _is_complete(false),
2670 MemBarNode(C, adr_type, rawoop)
2671 {
2672 init_class_id(Class_Initialize);
2673
2674 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
2675 assert(in(RawAddress) == rawoop, "proper init");
2676 // Note: allocation() can be NULL, for secondary initialization barriers
2677 }
2678
2679 // Since this node is not matched, it will be processed by the
2680 // register allocator. Declare that there are no constraints
2681 // on the allocation of the RawAddress edge.
2682 const RegMask &InitializeNode::in_RegMask(uint idx) const {
2683 // This edge should be set to top, by the set_complete. But be conservative.
2684 if (idx == InitializeNode::RawAddress)
2685 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
2686 return RegMask::Empty;
2687 }
2688
2689 Node* InitializeNode::memory(uint alias_idx) {
2690 Node* mem = in(Memory);
2691 if (mem->is_MergeMem()) {
2692 return mem->as_MergeMem()->memory_at(alias_idx);
2693 } else {
2694 // incoming raw memory is not split
2695 return mem;
2696 }
2697 }
2698
2699 bool InitializeNode::is_non_zero() {
2700 if (is_complete()) return false;
2701 remove_extra_zeroes();
2702 return (req() > RawStores);
2703 }
2704
2705 void InitializeNode::set_complete(PhaseGVN* phase) {
2706 assert(!is_complete(), "caller responsibility");
2707 _is_complete = true;
2708
2709 // After this node is complete, it contains a bunch of
2710 // raw-memory initializations. There is no need for
2711 // it to have anything to do with non-raw memory effects.
2712 // Therefore, tell all non-raw users to re-optimize themselves,
2713 // after skipping the memory effects of this initialization.
2714 PhaseIterGVN* igvn = phase->is_IterGVN();
2715 if (igvn) igvn->add_users_to_worklist(this);
2716 }
2717
2718 // convenience function
2719 // return false if the init contains any stores already
2720 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
2721 InitializeNode* init = initialization();
2722 if (init == NULL || init->is_complete()) return false;
2723 init->remove_extra_zeroes();
2724 // for now, if this allocation has already collected any inits, bail:
2725 if (init->is_non_zero()) return false;
2726 init->set_complete(phase);
2727 return true;
2728 }
2729
2730 void InitializeNode::remove_extra_zeroes() {
2731 if (req() == RawStores) return;
2732 Node* zmem = zero_memory();
2733 uint fill = RawStores;
2734 for (uint i = fill; i < req(); i++) {
2735 Node* n = in(i);
2736 if (n->is_top() || n == zmem) continue; // skip
2737 if (fill < i) set_req(fill, n); // compact
2738 ++fill;
2739 }
2740 // delete any empty spaces created:
2741 while (fill < req()) {
2742 del_req(fill);
2743 }
2744 }
2745
2746 // Helper for remembering which stores go with which offsets.
2747 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) {
2748 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
2749 intptr_t offset = -1;
2750 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
2751 phase, offset);
2752 if (base == NULL) return -1; // something is dead,
2753 if (offset < 0) return -1; // dead, dead
2754 return offset;
2755 }
2756
2757 // Helper for proving that an initialization expression is
2758 // "simple enough" to be folded into an object initialization.
2759 // Attempts to prove that a store's initial value 'n' can be captured
2760 // within the initialization without creating a vicious cycle, such as:
2761 // { Foo p = new Foo(); p.next = p; }
2762 // True for constants and parameters and small combinations thereof.
2763 bool InitializeNode::detect_init_independence(Node* n,
2764 bool st_is_pinned,
2765 int& count) {
2766 if (n == NULL) return true; // (can this really happen?)
2767 if (n->is_Proj()) n = n->in(0);
2768 if (n == this) return false; // found a cycle
2769 if (n->is_Con()) return true;
2770 if (n->is_Start()) return true; // params, etc., are OK
2771 if (n->is_Root()) return true; // even better
2772
2773 Node* ctl = n->in(0);
2774 if (ctl != NULL && !ctl->is_top()) {
2775 if (ctl->is_Proj()) ctl = ctl->in(0);
2776 if (ctl == this) return false;
2777
2778 // If we already know that the enclosing memory op is pinned right after
2779 // the init, then any control flow that the store has picked up
2780 // must have preceded the init, or else be equal to the init.
2781 // Even after loop optimizations (which might change control edges)
2782 // a store is never pinned *before* the availability of its inputs.
2783 if (!MemNode::all_controls_dominate(n, this))
2784 return false; // failed to prove a good control
2785
2786 }
2787
2788 // Check data edges for possible dependencies on 'this'.
2789 if ((count += 1) > 20) return false; // complexity limit
2790 for (uint i = 1; i < n->req(); i++) {
2791 Node* m = n->in(i);
2792 if (m == NULL || m == n || m->is_top()) continue;
2793 uint first_i = n->find_edge(m);
2794 if (i != first_i) continue; // process duplicate edge just once
2795 if (!detect_init_independence(m, st_is_pinned, count)) {
2796 return false;
2797 }
2798 }
2799
2800 return true;
2801 }
2802
2803 // Here are all the checks a Store must pass before it can be moved into
2804 // an initialization. Returns zero if a check fails.
2805 // On success, returns the (constant) offset to which the store applies,
2806 // within the initialized memory.
2807 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase) {
2808 const int FAIL = 0;
2809 if (st->req() != MemNode::ValueIn + 1)
2810 return FAIL; // an inscrutable StoreNode (card mark?)
2811 Node* ctl = st->in(MemNode::Control);
2812 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this))
2813 return FAIL; // must be unconditional after the initialization
2814 Node* mem = st->in(MemNode::Memory);
2815 if (!(mem->is_Proj() && mem->in(0) == this))
2816 return FAIL; // must not be preceded by other stores
2817 Node* adr = st->in(MemNode::Address);
2818 intptr_t offset;
2819 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
2820 if (alloc == NULL)
2821 return FAIL; // inscrutable address
2822 if (alloc != allocation())
2823 return FAIL; // wrong allocation! (store needs to float up)
2824 Node* val = st->in(MemNode::ValueIn);
2825 int complexity_count = 0;
2826 if (!detect_init_independence(val, true, complexity_count))
2827 return FAIL; // stored value must be 'simple enough'
2828
2829 return offset; // success
2830 }
2831
2832 // Find the captured store in(i) which corresponds to the range
2833 // [start..start+size) in the initialized object.
2834 // If there is one, return its index i. If there isn't, return the
2835 // negative of the index where it should be inserted.
2836 // Return 0 if the queried range overlaps an initialization boundary
2837 // or if dead code is encountered.
2838 // If size_in_bytes is zero, do not bother with overlap checks.
2839 int InitializeNode::captured_store_insertion_point(intptr_t start,
2840 int size_in_bytes,
2841 PhaseTransform* phase) {
2842 const int FAIL = 0, MAX_STORE = BytesPerLong;
2843
2844 if (is_complete())
2845 return FAIL; // arraycopy got here first; punt
2846
2847 assert(allocation() != NULL, "must be present");
2848
2849 // no negatives, no header fields:
2850 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
2851
2852 // after a certain size, we bail out on tracking all the stores:
2853 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
2854 if (start >= ti_limit) return FAIL;
2855
2856 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
2857 if (i >= limit) return -(int)i; // not found; here is where to put it
2858
2859 Node* st = in(i);
2860 intptr_t st_off = get_store_offset(st, phase);
2861 if (st_off < 0) {
2862 if (st != zero_memory()) {
2863 return FAIL; // bail out if there is dead garbage
2864 }
2865 } else if (st_off > start) {
2866 // ...we are done, since stores are ordered
2867 if (st_off < start + size_in_bytes) {
2868 return FAIL; // the next store overlaps
2869 }
2870 return -(int)i; // not found; here is where to put it
2871 } else if (st_off < start) {
2872 if (size_in_bytes != 0 &&
2873 start < st_off + MAX_STORE &&
2874 start < st_off + st->as_Store()->memory_size()) {
2875 return FAIL; // the previous store overlaps
2876 }
2877 } else {
2878 if (size_in_bytes != 0 &&
2879 st->as_Store()->memory_size() != size_in_bytes) {
2880 return FAIL; // mismatched store size
2881 }
2882 return i;
2883 }
2884
2885 ++i;
2886 }
2887 }
2888
2889 // Look for a captured store which initializes at the offset 'start'
2890 // with the given size. If there is no such store, and no other
2891 // initialization interferes, then return zero_memory (the memory
2892 // projection of the AllocateNode).
2893 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
2894 PhaseTransform* phase) {
2895 assert(stores_are_sane(phase), "");
2896 int i = captured_store_insertion_point(start, size_in_bytes, phase);
2897 if (i == 0) {
2898 return NULL; // something is dead
2899 } else if (i < 0) {
2900 return zero_memory(); // just primordial zero bits here
2901 } else {
2902 Node* st = in(i); // here is the store at this position
2903 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
2904 return st;
2905 }
2906 }
2907
2908 // Create, as a raw pointer, an address within my new object at 'offset'.
2909 Node* InitializeNode::make_raw_address(intptr_t offset,
2910 PhaseTransform* phase) {
2911 Node* addr = in(RawAddress);
2912 if (offset != 0) {
2913 Compile* C = phase->C;
2914 addr = phase->transform( new (C, 4) AddPNode(C->top(), addr,
2915 phase->MakeConX(offset)) );
2916 }
2917 return addr;
2918 }
2919
2920 // Clone the given store, converting it into a raw store
2921 // initializing a field or element of my new object.
2922 // Caller is responsible for retiring the original store,
2923 // with subsume_node or the like.
2924 //
2925 // From the example above InitializeNode::InitializeNode,
2926 // here are the old stores to be captured:
2927 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
2928 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
2929 //
2930 // Here is the changed code; note the extra edges on init:
2931 // alloc = (Allocate ...)
2932 // rawoop = alloc.RawAddress
2933 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
2934 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
2935 // init = (Initialize alloc.Control alloc.Memory rawoop
2936 // rawstore1 rawstore2)
2937 //
2938 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
2939 PhaseTransform* phase) {
2940 assert(stores_are_sane(phase), "");
2941
2942 if (start < 0) return NULL;
2943 assert(can_capture_store(st, phase) == start, "sanity");
2944
2945 Compile* C = phase->C;
2946 int size_in_bytes = st->memory_size();
2947 int i = captured_store_insertion_point(start, size_in_bytes, phase);
2948 if (i == 0) return NULL; // bail out
2949 Node* prev_mem = NULL; // raw memory for the captured store
2950 if (i > 0) {
2951 prev_mem = in(i); // there is a pre-existing store under this one
2952 set_req(i, C->top()); // temporarily disconnect it
2953 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
2954 } else {
2955 i = -i; // no pre-existing store
2956 prev_mem = zero_memory(); // a slice of the newly allocated object
2957 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
2958 set_req(--i, C->top()); // reuse this edge; it has been folded away
2959 else
2960 ins_req(i, C->top()); // build a new edge
2961 }
2962 Node* new_st = st->clone();
2963 new_st->set_req(MemNode::Control, in(Control));
2964 new_st->set_req(MemNode::Memory, prev_mem);
2965 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
2966 new_st = phase->transform(new_st);
2967
2968 // At this point, new_st might have swallowed a pre-existing store
2969 // at the same offset, or perhaps new_st might have disappeared,
2970 // if it redundantly stored the same value (or zero to fresh memory).
2971
2972 // In any case, wire it in:
2973 set_req(i, new_st);
2974
2975 // The caller may now kill the old guy.
2976 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
2977 assert(check_st == new_st || check_st == NULL, "must be findable");
2978 assert(!is_complete(), "");
2979 return new_st;
2980 }
2981
2982 static bool store_constant(jlong* tiles, int num_tiles,
2983 intptr_t st_off, int st_size,
2984 jlong con) {
2985 if ((st_off & (st_size-1)) != 0)
2986 return false; // strange store offset (assume size==2**N)
2987 address addr = (address)tiles + st_off;
2988 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
2989 switch (st_size) {
2990 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
2991 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
2992 case sizeof(jint): *(jint*) addr = (jint) con; break;
2993 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
2994 default: return false; // strange store size (detect size!=2**N here)
2995 }
2996 return true; // return success to caller
2997 }
2998
2999 // Coalesce subword constants into int constants and possibly
3000 // into long constants. The goal, if the CPU permits,
3001 // is to initialize the object with a small number of 64-bit tiles.
3002 // Also, convert floating-point constants to bit patterns.
3003 // Non-constants are not relevant to this pass.
3004 //
3005 // In terms of the running example on InitializeNode::InitializeNode
3006 // and InitializeNode::capture_store, here is the transformation
3007 // of rawstore1 and rawstore2 into rawstore12:
3008 // alloc = (Allocate ...)
3009 // rawoop = alloc.RawAddress
3010 // tile12 = 0x00010002
3011 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
3012 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
3013 //
3014 void
3015 InitializeNode::coalesce_subword_stores(intptr_t header_size,
3016 Node* size_in_bytes,
3017 PhaseGVN* phase) {
3018 Compile* C = phase->C;
3019
3020 assert(stores_are_sane(phase), "");
3021 // Note: After this pass, they are not completely sane,
3022 // since there may be some overlaps.
3023
3024 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
3025
3026 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3027 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
3028 size_limit = MIN2(size_limit, ti_limit);
3029 size_limit = align_size_up(size_limit, BytesPerLong);
3030 int num_tiles = size_limit / BytesPerLong;
3031
3032 // allocate space for the tile map:
3033 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
3034 jlong tiles_buf[small_len];
3035 Node* nodes_buf[small_len];
3036 jlong inits_buf[small_len];
3037 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
3038 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3039 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
3040 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
3041 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
3042 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3043 // tiles: exact bitwise model of all primitive constants
3044 // nodes: last constant-storing node subsumed into the tiles model
3045 // inits: which bytes (in each tile) are touched by any initializations
3046
3047 //// Pass A: Fill in the tile model with any relevant stores.
3048
3049 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
3050 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
3051 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
3052 Node* zmem = zero_memory(); // initially zero memory state
3053 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3054 Node* st = in(i);
3055 intptr_t st_off = get_store_offset(st, phase);
3056
3057 // Figure out the store's offset and constant value:
3058 if (st_off < header_size) continue; //skip (ignore header)
3059 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
3060 int st_size = st->as_Store()->memory_size();
3061 if (st_off + st_size > size_limit) break;
3062
3063 // Record which bytes are touched, whether by constant or not.
3064 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
3065 continue; // skip (strange store size)
3066
3067 const Type* val = phase->type(st->in(MemNode::ValueIn));
3068 if (!val->singleton()) continue; //skip (non-con store)
3069 BasicType type = val->basic_type();
3070
3071 jlong con = 0;
3072 switch (type) {
3073 case T_INT: con = val->is_int()->get_con(); break;
3074 case T_LONG: con = val->is_long()->get_con(); break;
3075 case T_FLOAT: con = jint_cast(val->getf()); break;
3076 case T_DOUBLE: con = jlong_cast(val->getd()); break;
3077 default: continue; //skip (odd store type)
3078 }
3079
3080 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
3081 st->Opcode() == Op_StoreL) {
3082 continue; // This StoreL is already optimal.
3083 }
3084
3085 // Store down the constant.
3086 store_constant(tiles, num_tiles, st_off, st_size, con);
3087
3088 intptr_t j = st_off >> LogBytesPerLong;
3089
3090 if (type == T_INT && st_size == BytesPerInt
3091 && (st_off & BytesPerInt) == BytesPerInt) {
3092 jlong lcon = tiles[j];
3093 if (!Matcher::isSimpleConstant64(lcon) &&
3094 st->Opcode() == Op_StoreI) {
3095 // This StoreI is already optimal by itself.
3096 jint* intcon = (jint*) &tiles[j];
3097 intcon[1] = 0; // undo the store_constant()
3098
3099 // If the previous store is also optimal by itself, back up and
3100 // undo the action of the previous loop iteration... if we can.
3101 // But if we can't, just let the previous half take care of itself.
3102 st = nodes[j];
3103 st_off -= BytesPerInt;
3104 con = intcon[0];
3105 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) {
3106 assert(st_off >= header_size, "still ignoring header");
3107 assert(get_store_offset(st, phase) == st_off, "must be");
3108 assert(in(i-1) == zmem, "must be");
3109 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
3110 assert(con == tcon->is_int()->get_con(), "must be");
3111 // Undo the effects of the previous loop trip, which swallowed st:
3112 intcon[0] = 0; // undo store_constant()
3113 set_req(i-1, st); // undo set_req(i, zmem)
3114 nodes[j] = NULL; // undo nodes[j] = st
3115 --old_subword; // undo ++old_subword
3116 }
3117 continue; // This StoreI is already optimal.
3118 }
3119 }
3120
3121 // This store is not needed.
3122 set_req(i, zmem);
3123 nodes[j] = st; // record for the moment
3124 if (st_size < BytesPerLong) // something has changed
3125 ++old_subword; // includes int/float, but who's counting...
3126 else ++old_long;
3127 }
3128
3129 if ((old_subword + old_long) == 0)
3130 return; // nothing more to do
3131
3132 //// Pass B: Convert any non-zero tiles into optimal constant stores.
3133 // Be sure to insert them before overlapping non-constant stores.
3134 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
3135 for (int j = 0; j < num_tiles; j++) {
3136 jlong con = tiles[j];
3137 jlong init = inits[j];
3138 if (con == 0) continue;
3139 jint con0, con1; // split the constant, address-wise
3140 jint init0, init1; // split the init map, address-wise
3141 { union { jlong con; jint intcon[2]; } u;
3142 u.con = con;
3143 con0 = u.intcon[0];
3144 con1 = u.intcon[1];
3145 u.con = init;
3146 init0 = u.intcon[0];
3147 init1 = u.intcon[1];
3148 }
3149
3150 Node* old = nodes[j];
3151 assert(old != NULL, "need the prior store");
3152 intptr_t offset = (j * BytesPerLong);
3153
3154 bool split = !Matcher::isSimpleConstant64(con);
3155
3156 if (offset < header_size) {
3157 assert(offset + BytesPerInt >= header_size, "second int counts");
3158 assert(*(jint*)&tiles[j] == 0, "junk in header");
3159 split = true; // only the second word counts
3160 // Example: int a[] = { 42 ... }
3161 } else if (con0 == 0 && init0 == -1) {
3162 split = true; // first word is covered by full inits
3163 // Example: int a[] = { ... foo(), 42 ... }
3164 } else if (con1 == 0 && init1 == -1) {
3165 split = true; // second word is covered by full inits
3166 // Example: int a[] = { ... 42, foo() ... }
3167 }
3168
3169 // Here's a case where init0 is neither 0 nor -1:
3170 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
3171 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
3172 // In this case the tile is not split; it is (jlong)42.
3173 // The big tile is stored down, and then the foo() value is inserted.
3174 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
3175
3176 Node* ctl = old->in(MemNode::Control);
3177 Node* adr = make_raw_address(offset, phase);
3178 const TypePtr* atp = TypeRawPtr::BOTTOM;
3179
3180 // One or two coalesced stores to plop down.
3181 Node* st[2];
3182 intptr_t off[2];
3183 int nst = 0;
3184 if (!split) {
3185 ++new_long;
3186 off[nst] = offset;
3187 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3188 phase->longcon(con), T_LONG);
3189 } else {
3190 // Omit either if it is a zero.
3191 if (con0 != 0) {
3192 ++new_int;
3193 off[nst] = offset;
3194 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3195 phase->intcon(con0), T_INT);
3196 }
3197 if (con1 != 0) {
3198 ++new_int;
3199 offset += BytesPerInt;
3200 adr = make_raw_address(offset, phase);
3201 off[nst] = offset;
3202 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3203 phase->intcon(con1), T_INT);
3204 }
3205 }
3206
3207 // Insert second store first, then the first before the second.
3208 // Insert each one just before any overlapping non-constant stores.
3209 while (nst > 0) {
3210 Node* st1 = st[--nst];
3211 C->copy_node_notes_to(st1, old);
3212 st1 = phase->transform(st1);
3213 offset = off[nst];
3214 assert(offset >= header_size, "do not smash header");
3215 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
3216 guarantee(ins_idx != 0, "must re-insert constant store");
3217 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
3218 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
3219 set_req(--ins_idx, st1);
3220 else
3221 ins_req(ins_idx, st1);
3222 }
3223 }
3224
3225 if (PrintCompilation && WizardMode)
3226 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
3227 old_subword, old_long, new_int, new_long);
3228 if (C->log() != NULL)
3229 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
3230 old_subword, old_long, new_int, new_long);
3231
3232 // Clean up any remaining occurrences of zmem:
3233 remove_extra_zeroes();
3234 }
3235
3236 // Explore forward from in(start) to find the first fully initialized
3237 // word, and return its offset. Skip groups of subword stores which
3238 // together initialize full words. If in(start) is itself part of a
3239 // fully initialized word, return the offset of in(start). If there
3240 // are no following full-word stores, or if something is fishy, return
3241 // a negative value.
3242 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
3243 int int_map = 0;
3244 intptr_t int_map_off = 0;
3245 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
3246
3247 for (uint i = start, limit = req(); i < limit; i++) {
3248 Node* st = in(i);
3249
3250 intptr_t st_off = get_store_offset(st, phase);
3251 if (st_off < 0) break; // return conservative answer
3252
3253 int st_size = st->as_Store()->memory_size();
3254 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
3255 return st_off; // we found a complete word init
3256 }
3257
3258 // update the map:
3259
3260 intptr_t this_int_off = align_size_down(st_off, BytesPerInt);
3261 if (this_int_off != int_map_off) {
3262 // reset the map:
3263 int_map = 0;
3264 int_map_off = this_int_off;
3265 }
3266
3267 int subword_off = st_off - this_int_off;
3268 int_map |= right_n_bits(st_size) << subword_off;
3269 if ((int_map & FULL_MAP) == FULL_MAP) {
3270 return this_int_off; // we found a complete word init
3271 }
3272
3273 // Did this store hit or cross the word boundary?
3274 intptr_t next_int_off = align_size_down(st_off + st_size, BytesPerInt);
3275 if (next_int_off == this_int_off + BytesPerInt) {
3276 // We passed the current int, without fully initializing it.
3277 int_map_off = next_int_off;
3278 int_map >>= BytesPerInt;
3279 } else if (next_int_off > this_int_off + BytesPerInt) {
3280 // We passed the current and next int.
3281 return this_int_off + BytesPerInt;
3282 }
3283 }
3284
3285 return -1;
3286 }
3287
3288
3289 // Called when the associated AllocateNode is expanded into CFG.
3290 // At this point, we may perform additional optimizations.
3291 // Linearize the stores by ascending offset, to make memory
3292 // activity as coherent as possible.
3293 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
3294 intptr_t header_size,
3295 Node* size_in_bytes,
3296 PhaseGVN* phase) {
3297 assert(!is_complete(), "not already complete");
3298 assert(stores_are_sane(phase), "");
3299 assert(allocation() != NULL, "must be present");
3300
3301 remove_extra_zeroes();
3302
3303 if (ReduceFieldZeroing || ReduceBulkZeroing)
3304 // reduce instruction count for common initialization patterns
3305 coalesce_subword_stores(header_size, size_in_bytes, phase);
3306
3307 Node* zmem = zero_memory(); // initially zero memory state
3308 Node* inits = zmem; // accumulating a linearized chain of inits
3309 #ifdef ASSERT
3310 intptr_t first_offset = allocation()->minimum_header_size();
3311 intptr_t last_init_off = first_offset; // previous init offset
3312 intptr_t last_init_end = first_offset; // previous init offset+size
3313 intptr_t last_tile_end = first_offset; // previous tile offset+size
3314 #endif
3315 intptr_t zeroes_done = header_size;
3316
3317 bool do_zeroing = true; // we might give up if inits are very sparse
3318 int big_init_gaps = 0; // how many large gaps have we seen?
3319
3320 if (ZeroTLAB) do_zeroing = false;
3321 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
3322
3323 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3324 Node* st = in(i);
3325 intptr_t st_off = get_store_offset(st, phase);
3326 if (st_off < 0)
3327 break; // unknown junk in the inits
3328 if (st->in(MemNode::Memory) != zmem)
3329 break; // complicated store chains somehow in list
3330
3331 int st_size = st->as_Store()->memory_size();
3332 intptr_t next_init_off = st_off + st_size;
3333
3334 if (do_zeroing && zeroes_done < next_init_off) {
3335 // See if this store needs a zero before it or under it.
3336 intptr_t zeroes_needed = st_off;
3337
3338 if (st_size < BytesPerInt) {
3339 // Look for subword stores which only partially initialize words.
3340 // If we find some, we must lay down some word-level zeroes first,
3341 // underneath the subword stores.
3342 //
3343 // Examples:
3344 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
3345 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
3346 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
3347 //
3348 // Note: coalesce_subword_stores may have already done this,
3349 // if it was prompted by constant non-zero subword initializers.
3350 // But this case can still arise with non-constant stores.
3351
3352 intptr_t next_full_store = find_next_fullword_store(i, phase);
3353
3354 // In the examples above:
3355 // in(i) p q r s x y z
3356 // st_off 12 13 14 15 12 13 14
3357 // st_size 1 1 1 1 1 1 1
3358 // next_full_s. 12 16 16 16 16 16 16
3359 // z's_done 12 16 16 16 12 16 12
3360 // z's_needed 12 16 16 16 16 16 16
3361 // zsize 0 0 0 0 4 0 4
3362 if (next_full_store < 0) {
3363 // Conservative tack: Zero to end of current word.
3364 zeroes_needed = align_size_up(zeroes_needed, BytesPerInt);
3365 } else {
3366 // Zero to beginning of next fully initialized word.
3367 // Or, don't zero at all, if we are already in that word.
3368 assert(next_full_store >= zeroes_needed, "must go forward");
3369 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
3370 zeroes_needed = next_full_store;
3371 }
3372 }
3373
3374 if (zeroes_needed > zeroes_done) {
3375 intptr_t zsize = zeroes_needed - zeroes_done;
3376 // Do some incremental zeroing on rawmem, in parallel with inits.
3377 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3378 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3379 zeroes_done, zeroes_needed,
3380 phase);
3381 zeroes_done = zeroes_needed;
3382 if (zsize > Matcher::init_array_short_size && ++big_init_gaps > 2)
3383 do_zeroing = false; // leave the hole, next time
3384 }
3385 }
3386
3387 // Collect the store and move on:
3388 st->set_req(MemNode::Memory, inits);
3389 inits = st; // put it on the linearized chain
3390 set_req(i, zmem); // unhook from previous position
3391
3392 if (zeroes_done == st_off)
3393 zeroes_done = next_init_off;
3394
3395 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
3396
3397 #ifdef ASSERT
3398 // Various order invariants. Weaker than stores_are_sane because
3399 // a large constant tile can be filled in by smaller non-constant stores.
3400 assert(st_off >= last_init_off, "inits do not reverse");
3401 last_init_off = st_off;
3402 const Type* val = NULL;
3403 if (st_size >= BytesPerInt &&
3404 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
3405 (int)val->basic_type() < (int)T_OBJECT) {
3406 assert(st_off >= last_tile_end, "tiles do not overlap");
3407 assert(st_off >= last_init_end, "tiles do not overwrite inits");
3408 last_tile_end = MAX2(last_tile_end, next_init_off);
3409 } else {
3410 intptr_t st_tile_end = align_size_up(next_init_off, BytesPerLong);
3411 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
3412 assert(st_off >= last_init_end, "inits do not overlap");
3413 last_init_end = next_init_off; // it's a non-tile
3414 }
3415 #endif //ASSERT
3416 }
3417
3418 remove_extra_zeroes(); // clear out all the zmems left over
3419 add_req(inits);
3420
3421 if (!ZeroTLAB) {
3422 // If anything remains to be zeroed, zero it all now.
3423 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3424 // if it is the last unused 4 bytes of an instance, forget about it
3425 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
3426 if (zeroes_done + BytesPerLong >= size_limit) {
3427 assert(allocation() != NULL, "");
3428 Node* klass_node = allocation()->in(AllocateNode::KlassNode);
3429 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass();
3430 if (zeroes_done == k->layout_helper())
3431 zeroes_done = size_limit;
3432 }
3433 if (zeroes_done < size_limit) {
3434 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3435 zeroes_done, size_in_bytes, phase);
3436 }
3437 }
3438
3439 set_complete(phase);
3440 return rawmem;
3441 }
3442
3443
3444 #ifdef ASSERT
3445 bool InitializeNode::stores_are_sane(PhaseTransform* phase) {
3446 if (is_complete())
3447 return true; // stores could be anything at this point
3448 assert(allocation() != NULL, "must be present");
3449 intptr_t last_off = allocation()->minimum_header_size();
3450 for (uint i = InitializeNode::RawStores; i < req(); i++) {
3451 Node* st = in(i);
3452 intptr_t st_off = get_store_offset(st, phase);
3453 if (st_off < 0) continue; // ignore dead garbage
3454 if (last_off > st_off) {
3455 tty->print_cr("*** bad store offset at %d: %d > %d", i, last_off, st_off);
3456 this->dump(2);
3457 assert(false, "ascending store offsets");
3458 return false;
3459 }
3460 last_off = st_off + st->as_Store()->memory_size();
3461 }
3462 return true;
3463 }
3464 #endif //ASSERT
3465
3466
3467
3468
3469 //============================MergeMemNode=====================================
3470 //
3471 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
3472 // contributing store or call operations. Each contributor provides the memory
3473 // state for a particular "alias type" (see Compile::alias_type). For example,
3474 // if a MergeMem has an input X for alias category #6, then any memory reference
3475 // to alias category #6 may use X as its memory state input, as an exact equivalent
3476 // to using the MergeMem as a whole.
3477 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
3478 //
3479 // (Here, the <N> notation gives the index of the relevant adr_type.)
3480 //
3481 // In one special case (and more cases in the future), alias categories overlap.
3482 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
3483 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
3484 // it is exactly equivalent to that state W:
3485 // MergeMem(<Bot>: W) <==> W
3486 //
3487 // Usually, the merge has more than one input. In that case, where inputs
3488 // overlap (i.e., one is Bot), the narrower alias type determines the memory
3489 // state for that type, and the wider alias type (Bot) fills in everywhere else:
3490 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
3491 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
3492 //
3493 // A merge can take a "wide" memory state as one of its narrow inputs.
3494 // This simply means that the merge observes out only the relevant parts of
3495 // the wide input. That is, wide memory states arriving at narrow merge inputs
3496 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
3497 //
3498 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
3499 // and that memory slices "leak through":
3500 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
3501 //
3502 // But, in such a cascade, repeated memory slices can "block the leak":
3503 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
3504 //
3505 // In the last example, Y is not part of the combined memory state of the
3506 // outermost MergeMem. The system must, of course, prevent unschedulable
3507 // memory states from arising, so you can be sure that the state Y is somehow
3508 // a precursor to state Y'.
3509 //
3510 //
3511 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
3512 // of each MergeMemNode array are exactly the numerical alias indexes, including
3513 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
3514 // Compile::alias_type (and kin) produce and manage these indexes.
3515 //
3516 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
3517 // (Note that this provides quick access to the top node inside MergeMem methods,
3518 // without the need to reach out via TLS to Compile::current.)
3519 //
3520 // As a consequence of what was just described, a MergeMem that represents a full
3521 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
3522 // containing all alias categories.
3523 //
3524 // MergeMem nodes never (?) have control inputs, so in(0) is NULL.
3525 //
3526 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
3527 // a memory state for the alias type <N>, or else the top node, meaning that
3528 // there is no particular input for that alias type. Note that the length of
3529 // a MergeMem is variable, and may be extended at any time to accommodate new
3530 // memory states at larger alias indexes. When merges grow, they are of course
3531 // filled with "top" in the unused in() positions.
3532 //
3533 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
3534 // (Top was chosen because it works smoothly with passes like GCM.)
3535 //
3536 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
3537 // the type of random VM bits like TLS references.) Since it is always the
3538 // first non-Bot memory slice, some low-level loops use it to initialize an
3539 // index variable: for (i = AliasIdxRaw; i < req(); i++).
3540 //
3541 //
3542 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
3543 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
3544 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
3545 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
3546 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
3547 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
3548 //
3549 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
3550 // really that different from the other memory inputs. An abbreviation called
3551 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
3552 //
3553 //
3554 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
3555 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
3556 // that "emerges though" the base memory will be marked as excluding the alias types
3557 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
3558 //
3559 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
3560 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
3561 //
3562 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
3563 // (It is currently unimplemented.) As you can see, the resulting merge is
3564 // actually a disjoint union of memory states, rather than an overlay.
3565 //
3566
3567 //------------------------------MergeMemNode-----------------------------------
3568 Node* MergeMemNode::make_empty_memory() {
3569 Node* empty_memory = (Node*) Compile::current()->top();
3570 assert(empty_memory->is_top(), "correct sentinel identity");
3571 return empty_memory;
3572 }
3573
3574 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
3575 init_class_id(Class_MergeMem);
3576 // all inputs are nullified in Node::Node(int)
3577 // set_input(0, NULL); // no control input
3578
3579 // Initialize the edges uniformly to top, for starters.
3580 Node* empty_mem = make_empty_memory();
3581 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
3582 init_req(i,empty_mem);
3583 }
3584 assert(empty_memory() == empty_mem, "");
3585
3586 if( new_base != NULL && new_base->is_MergeMem() ) {
3587 MergeMemNode* mdef = new_base->as_MergeMem();
3588 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
3589 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
3590 mms.set_memory(mms.memory2());
3591 }
3592 assert(base_memory() == mdef->base_memory(), "");
3593 } else {
3594 set_base_memory(new_base);
3595 }
3596 }
3597
3598 // Make a new, untransformed MergeMem with the same base as 'mem'.
3599 // If mem is itself a MergeMem, populate the result with the same edges.
3600 MergeMemNode* MergeMemNode::make(Compile* C, Node* mem) {
3601 return new(C, 1+Compile::AliasIdxRaw) MergeMemNode(mem);
3602 }
3603
3604 //------------------------------cmp--------------------------------------------
3605 uint MergeMemNode::hash() const { return NO_HASH; }
3606 uint MergeMemNode::cmp( const Node &n ) const {
3607 return (&n == this); // Always fail except on self
3608 }
3609
3610 //------------------------------Identity---------------------------------------
3611 Node* MergeMemNode::Identity(PhaseTransform *phase) {
3612 // Identity if this merge point does not record any interesting memory
3613 // disambiguations.
3614 Node* base_mem = base_memory();
3615 Node* empty_mem = empty_memory();
3616 if (base_mem != empty_mem) { // Memory path is not dead?
3617 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3618 Node* mem = in(i);
3619 if (mem != empty_mem && mem != base_mem) {
3620 return this; // Many memory splits; no change
3621 }
3622 }
3623 }
3624 return base_mem; // No memory splits; ID on the one true input
3625 }
3626
3627 //------------------------------Ideal------------------------------------------
3628 // This method is invoked recursively on chains of MergeMem nodes
3629 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3630 // Remove chain'd MergeMems
3631 //
3632 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
3633 // relative to the "in(Bot)". Since we are patching both at the same time,
3634 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
3635 // but rewrite each "in(i)" relative to the new "in(Bot)".
3636 Node *progress = NULL;
3637
3638
3639 Node* old_base = base_memory();
3640 Node* empty_mem = empty_memory();
3641 if (old_base == empty_mem)
3642 return NULL; // Dead memory path.
3643
3644 MergeMemNode* old_mbase;
3645 if (old_base != NULL && old_base->is_MergeMem())
3646 old_mbase = old_base->as_MergeMem();
3647 else
3648 old_mbase = NULL;
3649 Node* new_base = old_base;
3650
3651 // simplify stacked MergeMems in base memory
3652 if (old_mbase) new_base = old_mbase->base_memory();
3653
3654 // the base memory might contribute new slices beyond my req()
3655 if (old_mbase) grow_to_match(old_mbase);
3656
3657 // Look carefully at the base node if it is a phi.
3658 PhiNode* phi_base;
3659 if (new_base != NULL && new_base->is_Phi())
3660 phi_base = new_base->as_Phi();
3661 else
3662 phi_base = NULL;
3663
3664 Node* phi_reg = NULL;
3665 uint phi_len = (uint)-1;
3666 if (phi_base != NULL && !phi_base->is_copy()) {
3667 // do not examine phi if degraded to a copy
3668 phi_reg = phi_base->region();
3669 phi_len = phi_base->req();
3670 // see if the phi is unfinished
3671 for (uint i = 1; i < phi_len; i++) {
3672 if (phi_base->in(i) == NULL) {
3673 // incomplete phi; do not look at it yet!
3674 phi_reg = NULL;
3675 phi_len = (uint)-1;
3676 break;
3677 }
3678 }
3679 }
3680
3681 // Note: We do not call verify_sparse on entry, because inputs
3682 // can normalize to the base_memory via subsume_node or similar
3683 // mechanisms. This method repairs that damage.
3684
3685 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
3686
3687 // Look at each slice.
3688 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3689 Node* old_in = in(i);
3690 // calculate the old memory value
3691 Node* old_mem = old_in;
3692 if (old_mem == empty_mem) old_mem = old_base;
3693 assert(old_mem == memory_at(i), "");
3694
3695 // maybe update (reslice) the old memory value
3696
3697 // simplify stacked MergeMems
3698 Node* new_mem = old_mem;
3699 MergeMemNode* old_mmem;
3700 if (old_mem != NULL && old_mem->is_MergeMem())
3701 old_mmem = old_mem->as_MergeMem();
3702 else
3703 old_mmem = NULL;
3704 if (old_mmem == this) {
3705 // This can happen if loops break up and safepoints disappear.
3706 // A merge of BotPtr (default) with a RawPtr memory derived from a
3707 // safepoint can be rewritten to a merge of the same BotPtr with
3708 // the BotPtr phi coming into the loop. If that phi disappears
3709 // also, we can end up with a self-loop of the mergemem.
3710 // In general, if loops degenerate and memory effects disappear,
3711 // a mergemem can be left looking at itself. This simply means
3712 // that the mergemem's default should be used, since there is
3713 // no longer any apparent effect on this slice.
3714 // Note: If a memory slice is a MergeMem cycle, it is unreachable
3715 // from start. Update the input to TOP.
3716 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
3717 }
3718 else if (old_mmem != NULL) {
3719 new_mem = old_mmem->memory_at(i);
3720 }
3721 // else preceding memory was not a MergeMem
3722
3723 // replace equivalent phis (unfortunately, they do not GVN together)
3724 if (new_mem != NULL && new_mem != new_base &&
3725 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) {
3726 if (new_mem->is_Phi()) {
3727 PhiNode* phi_mem = new_mem->as_Phi();
3728 for (uint i = 1; i < phi_len; i++) {
3729 if (phi_base->in(i) != phi_mem->in(i)) {
3730 phi_mem = NULL;
3731 break;
3732 }
3733 }
3734 if (phi_mem != NULL) {
3735 // equivalent phi nodes; revert to the def
3736 new_mem = new_base;
3737 }
3738 }
3739 }
3740
3741 // maybe store down a new value
3742 Node* new_in = new_mem;
3743 if (new_in == new_base) new_in = empty_mem;
3744
3745 if (new_in != old_in) {
3746 // Warning: Do not combine this "if" with the previous "if"
3747 // A memory slice might have be be rewritten even if it is semantically
3748 // unchanged, if the base_memory value has changed.
3749 set_req(i, new_in);
3750 progress = this; // Report progress
3751 }
3752 }
3753
3754 if (new_base != old_base) {
3755 set_req(Compile::AliasIdxBot, new_base);
3756 // Don't use set_base_memory(new_base), because we need to update du.
3757 assert(base_memory() == new_base, "");
3758 progress = this;
3759 }
3760
3761 if( base_memory() == this ) {
3762 // a self cycle indicates this memory path is dead
3763 set_req(Compile::AliasIdxBot, empty_mem);
3764 }
3765
3766 // Resolve external cycles by calling Ideal on a MergeMem base_memory
3767 // Recursion must occur after the self cycle check above
3768 if( base_memory()->is_MergeMem() ) {
3769 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
3770 Node *m = phase->transform(new_mbase); // Rollup any cycles
3771 if( m != NULL && (m->is_top() ||
3772 m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem) ) {
3773 // propagate rollup of dead cycle to self
3774 set_req(Compile::AliasIdxBot, empty_mem);
3775 }
3776 }
3777
3778 if( base_memory() == empty_mem ) {
3779 progress = this;
3780 // Cut inputs during Parse phase only.
3781 // During Optimize phase a dead MergeMem node will be subsumed by Top.
3782 if( !can_reshape ) {
3783 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3784 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
3785 }
3786 }
3787 }
3788
3789 if( !progress && base_memory()->is_Phi() && can_reshape ) {
3790 // Check if PhiNode::Ideal's "Split phis through memory merges"
3791 // transform should be attempted. Look for this->phi->this cycle.
3792 uint merge_width = req();
3793 if (merge_width > Compile::AliasIdxRaw) {
3794 PhiNode* phi = base_memory()->as_Phi();
3795 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
3796 if (phi->in(i) == this) {
3797 phase->is_IterGVN()->_worklist.push(phi);
3798 break;
3799 }
3800 }
3801 }
3802 }
3803
3804 assert(progress || verify_sparse(), "please, no dups of base");
3805 return progress;
3806 }
3807
3808 //-------------------------set_base_memory-------------------------------------
3809 void MergeMemNode::set_base_memory(Node *new_base) {
3810 Node* empty_mem = empty_memory();
3811 set_req(Compile::AliasIdxBot, new_base);
3812 assert(memory_at(req()) == new_base, "must set default memory");
3813 // Clear out other occurrences of new_base:
3814 if (new_base != empty_mem) {
3815 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3816 if (in(i) == new_base) set_req(i, empty_mem);
3817 }
3818 }
3819 }
3820
3821 //------------------------------out_RegMask------------------------------------
3822 const RegMask &MergeMemNode::out_RegMask() const {
3823 return RegMask::Empty;
3824 }
3825
3826 //------------------------------dump_spec--------------------------------------
3827 #ifndef PRODUCT
3828 void MergeMemNode::dump_spec(outputStream *st) const {
3829 st->print(" {");
3830 Node* base_mem = base_memory();
3831 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
3832 Node* mem = memory_at(i);
3833 if (mem == base_mem) { st->print(" -"); continue; }
3834 st->print( " N%d:", mem->_idx );
3835 Compile::current()->get_adr_type(i)->dump_on(st);
3836 }
3837 st->print(" }");
3838 }
3839 #endif // !PRODUCT
3840
3841
3842 #ifdef ASSERT
3843 static bool might_be_same(Node* a, Node* b) {
3844 if (a == b) return true;
3845 if (!(a->is_Phi() || b->is_Phi())) return false;
3846 // phis shift around during optimization
3847 return true; // pretty stupid...
3848 }
3849
3850 // verify a narrow slice (either incoming or outgoing)
3851 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
3852 if (!VerifyAliases) return; // don't bother to verify unless requested
3853 if (is_error_reported()) return; // muzzle asserts when debugging an error
3854 if (Node::in_dump()) return; // muzzle asserts when printing
3855 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
3856 assert(n != NULL, "");
3857 // Elide intervening MergeMem's
3858 while (n->is_MergeMem()) {
3859 n = n->as_MergeMem()->memory_at(alias_idx);
3860 }
3861 Compile* C = Compile::current();
3862 const TypePtr* n_adr_type = n->adr_type();
3863 if (n == m->empty_memory()) {
3864 // Implicit copy of base_memory()
3865 } else if (n_adr_type != TypePtr::BOTTOM) {
3866 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type");
3867 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
3868 } else {
3869 // A few places like make_runtime_call "know" that VM calls are narrow,
3870 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
3871 bool expected_wide_mem = false;
3872 if (n == m->base_memory()) {
3873 expected_wide_mem = true;
3874 } else if (alias_idx == Compile::AliasIdxRaw ||
3875 n == m->memory_at(Compile::AliasIdxRaw)) {
3876 expected_wide_mem = true;
3877 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
3878 // memory can "leak through" calls on channels that
3879 // are write-once. Allow this also.
3880 expected_wide_mem = true;
3881 }
3882 assert(expected_wide_mem, "expected narrow slice replacement");
3883 }
3884 }
3885 #else // !ASSERT
3886 #define verify_memory_slice(m,i,n) (0) // PRODUCT version is no-op
3887 #endif
3888
3889
3890 //-----------------------------memory_at---------------------------------------
3891 Node* MergeMemNode::memory_at(uint alias_idx) const {
3892 assert(alias_idx >= Compile::AliasIdxRaw ||
3893 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0,
3894 "must avoid base_memory and AliasIdxTop");
3895
3896 // Otherwise, it is a narrow slice.
3897 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
3898 Compile *C = Compile::current();
3899 if (is_empty_memory(n)) {
3900 // the array is sparse; empty slots are the "top" node
3901 n = base_memory();
3902 assert(Node::in_dump()
3903 || n == NULL || n->bottom_type() == Type::TOP
3904 || n->adr_type() == TypePtr::BOTTOM
3905 || n->adr_type() == TypeRawPtr::BOTTOM
3906 || Compile::current()->AliasLevel() == 0,
3907 "must be a wide memory");
3908 // AliasLevel == 0 if we are organizing the memory states manually.
3909 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
3910 } else {
3911 // make sure the stored slice is sane
3912 #ifdef ASSERT
3913 if (is_error_reported() || Node::in_dump()) {
3914 } else if (might_be_same(n, base_memory())) {
3915 // Give it a pass: It is a mostly harmless repetition of the base.
3916 // This can arise normally from node subsumption during optimization.
3917 } else {
3918 verify_memory_slice(this, alias_idx, n);
3919 }
3920 #endif
3921 }
3922 return n;
3923 }
3924
3925 //---------------------------set_memory_at-------------------------------------
3926 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
3927 verify_memory_slice(this, alias_idx, n);
3928 Node* empty_mem = empty_memory();
3929 if (n == base_memory()) n = empty_mem; // collapse default
3930 uint need_req = alias_idx+1;
3931 if (req() < need_req) {
3932 if (n == empty_mem) return; // already the default, so do not grow me
3933 // grow the sparse array
3934 do {
3935 add_req(empty_mem);
3936 } while (req() < need_req);
3937 }
3938 set_req( alias_idx, n );
3939 }
3940
3941
3942
3943 //--------------------------iteration_setup------------------------------------
3944 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
3945 if (other != NULL) {
3946 grow_to_match(other);
3947 // invariant: the finite support of mm2 is within mm->req()
3948 #ifdef ASSERT
3949 for (uint i = req(); i < other->req(); i++) {
3950 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
3951 }
3952 #endif
3953 }
3954 // Replace spurious copies of base_memory by top.
3955 Node* base_mem = base_memory();
3956 if (base_mem != NULL && !base_mem->is_top()) {
3957 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
3958 if (in(i) == base_mem)
3959 set_req(i, empty_memory());
3960 }
3961 }
3962 }
3963
3964 //---------------------------grow_to_match-------------------------------------
3965 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
3966 Node* empty_mem = empty_memory();
3967 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
3968 // look for the finite support of the other memory
3969 for (uint i = other->req(); --i >= req(); ) {
3970 if (other->in(i) != empty_mem) {
3971 uint new_len = i+1;
3972 while (req() < new_len) add_req(empty_mem);
3973 break;
3974 }
3975 }
3976 }
3977
3978 //---------------------------verify_sparse-------------------------------------
3979 #ifndef PRODUCT
3980 bool MergeMemNode::verify_sparse() const {
3981 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
3982 Node* base_mem = base_memory();
3983 // The following can happen in degenerate cases, since empty==top.
3984 if (is_empty_memory(base_mem)) return true;
3985 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3986 assert(in(i) != NULL, "sane slice");
3987 if (in(i) == base_mem) return false; // should have been the sentinel value!
3988 }
3989 return true;
3990 }
3991
3992 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
3993 Node* n;
3994 n = mm->in(idx);
3995 if (mem == n) return true; // might be empty_memory()
3996 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
3997 if (mem == n) return true;
3998 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) {
3999 if (mem == n) return true;
4000 if (n == NULL) break;
4001 }
4002 return false;
4003 }
4004 #endif // !PRODUCT