Fri, 11 Jul 2008 01:14:44 -0700
Merge
1 /*
2 * Copyright 1997-2008 Sun Microsystems, Inc. All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
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23 */
25 // Portions of code courtesy of Clifford Click
27 // Optimization - Graph Style
29 #include "incls/_precompiled.incl"
30 #include "incls/_memnode.cpp.incl"
32 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st);
34 //=============================================================================
35 uint MemNode::size_of() const { return sizeof(*this); }
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 }
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);
55 Compile* C = Compile::current();
56 if( C->alias_type(_adr_type)->is_volatile() )
57 st->print(" Volatile!");
58 }
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 }
88 extern void print_alias_types();
90 #endif
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 *prev = NULL;
98 Node *result = mchain;
99 while (prev != result) {
100 prev = result;
101 // skip over a call which does not affect this memory slice
102 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {
103 Node *proj_in = result->in(0);
104 if (proj_in->is_Call()) {
105 CallNode *call = proj_in->as_Call();
106 if (!call->may_modify(t_adr, phase)) {
107 result = call->in(TypeFunc::Memory);
108 }
109 } else if (proj_in->is_Initialize()) {
110 AllocateNode* alloc = proj_in->as_Initialize()->allocation();
111 // Stop if this is the initialization for the object instance which
112 // which contains this memory slice, otherwise skip over it.
113 if (alloc != NULL && alloc->_idx != instance_id) {
114 result = proj_in->in(TypeFunc::Memory);
115 }
116 } else if (proj_in->is_MemBar()) {
117 result = proj_in->in(TypeFunc::Memory);
118 }
119 } else if (result->is_MergeMem()) {
120 result = step_through_mergemem(phase, result->as_MergeMem(), t_adr, NULL, tty);
121 }
122 }
123 return result;
124 }
126 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, PhaseGVN *phase) {
127 const TypeOopPtr *t_oop = t_adr->isa_oopptr();
128 bool is_instance = (t_oop != NULL) && t_oop->is_known_instance_field();
129 PhaseIterGVN *igvn = phase->is_IterGVN();
130 Node *result = mchain;
131 result = optimize_simple_memory_chain(result, t_adr, phase);
132 if (is_instance && igvn != NULL && result->is_Phi()) {
133 PhiNode *mphi = result->as_Phi();
134 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
135 const TypePtr *t = mphi->adr_type();
136 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
137 t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
138 t->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop) {
139 // clone the Phi with our address type
140 result = mphi->split_out_instance(t_adr, igvn);
141 } else {
142 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain");
143 }
144 }
145 return result;
146 }
148 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) {
149 uint alias_idx = phase->C->get_alias_index(tp);
150 Node *mem = mmem;
151 #ifdef ASSERT
152 {
153 // Check that current type is consistent with the alias index used during graph construction
154 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
155 bool consistent = adr_check == NULL || adr_check->empty() ||
156 phase->C->must_alias(adr_check, alias_idx );
157 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
158 if( !consistent && adr_check != NULL && !adr_check->empty() &&
159 tp->isa_aryptr() && tp->offset() == Type::OffsetBot &&
160 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot &&
161 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() ||
162 adr_check->offset() == oopDesc::klass_offset_in_bytes() ||
163 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) {
164 // don't assert if it is dead code.
165 consistent = true;
166 }
167 if( !consistent ) {
168 st->print("alias_idx==%d, adr_check==", alias_idx);
169 if( adr_check == NULL ) {
170 st->print("NULL");
171 } else {
172 adr_check->dump();
173 }
174 st->cr();
175 print_alias_types();
176 assert(consistent, "adr_check must match alias idx");
177 }
178 }
179 #endif
180 // TypeInstPtr::NOTNULL+any is an OOP with unknown offset - generally
181 // means an array I have not precisely typed yet. Do not do any
182 // alias stuff with it any time soon.
183 const TypeOopPtr *tinst = tp->isa_oopptr();
184 if( tp->base() != Type::AnyPtr &&
185 !(tinst &&
186 tinst->klass()->is_java_lang_Object() &&
187 tinst->offset() == Type::OffsetBot) ) {
188 // compress paths and change unreachable cycles to TOP
189 // If not, we can update the input infinitely along a MergeMem cycle
190 // Equivalent code in PhiNode::Ideal
191 Node* m = phase->transform(mmem);
192 // If tranformed to a MergeMem, get the desired slice
193 // Otherwise the returned node represents memory for every slice
194 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
195 // Update input if it is progress over what we have now
196 }
197 return mem;
198 }
200 //--------------------------Ideal_common---------------------------------------
201 // Look for degenerate control and memory inputs. Bypass MergeMem inputs.
202 // Unhook non-raw memories from complete (macro-expanded) initializations.
203 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
204 // If our control input is a dead region, kill all below the region
205 Node *ctl = in(MemNode::Control);
206 if (ctl && remove_dead_region(phase, can_reshape))
207 return this;
209 // Ignore if memory is dead, or self-loop
210 Node *mem = in(MemNode::Memory);
211 if( phase->type( mem ) == Type::TOP ) return NodeSentinel; // caller will return NULL
212 assert( mem != this, "dead loop in MemNode::Ideal" );
214 Node *address = in(MemNode::Address);
215 const Type *t_adr = phase->type( address );
216 if( t_adr == Type::TOP ) return NodeSentinel; // caller will return NULL
218 // Avoid independent memory operations
219 Node* old_mem = mem;
221 // The code which unhooks non-raw memories from complete (macro-expanded)
222 // initializations was removed. After macro-expansion all stores catched
223 // by Initialize node became raw stores and there is no information
224 // which memory slices they modify. So it is unsafe to move any memory
225 // operation above these stores. Also in most cases hooked non-raw memories
226 // were already unhooked by using information from detect_ptr_independence()
227 // and find_previous_store().
229 if (mem->is_MergeMem()) {
230 MergeMemNode* mmem = mem->as_MergeMem();
231 const TypePtr *tp = t_adr->is_ptr();
233 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
234 }
236 if (mem != old_mem) {
237 set_req(MemNode::Memory, mem);
238 return this;
239 }
241 // let the subclass continue analyzing...
242 return NULL;
243 }
245 // Helper function for proving some simple control dominations.
246 // Attempt to prove that all control inputs of 'dom' dominate 'sub'.
247 // Already assumes that 'dom' is available at 'sub', and that 'sub'
248 // is not a constant (dominated by the method's StartNode).
249 // Used by MemNode::find_previous_store to prove that the
250 // control input of a memory operation predates (dominates)
251 // an allocation it wants to look past.
252 bool MemNode::all_controls_dominate(Node* dom, Node* sub) {
253 if (dom == NULL || dom->is_top() || sub == NULL || sub->is_top())
254 return false; // Conservative answer for dead code
256 // Check 'dom'. Skip Proj and CatchProj nodes.
257 dom = dom->find_exact_control(dom);
258 if (dom == NULL || dom->is_top())
259 return false; // Conservative answer for dead code
261 if (dom == sub) {
262 // For the case when, for example, 'sub' is Initialize and the original
263 // 'dom' is Proj node of the 'sub'.
264 return false;
265 }
267 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub)
268 return true;
270 // 'dom' dominates 'sub' if its control edge and control edges
271 // of all its inputs dominate or equal to sub's control edge.
273 // Currently 'sub' is either Allocate, Initialize or Start nodes.
274 // Or Region for the check in LoadNode::Ideal();
275 // 'sub' should have sub->in(0) != NULL.
276 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() ||
277 sub->is_Region(), "expecting only these nodes");
279 // Get control edge of 'sub'.
280 Node* orig_sub = sub;
281 sub = sub->find_exact_control(sub->in(0));
282 if (sub == NULL || sub->is_top())
283 return false; // Conservative answer for dead code
285 assert(sub->is_CFG(), "expecting control");
287 if (sub == dom)
288 return true;
290 if (sub->is_Start() || sub->is_Root())
291 return false;
293 {
294 // Check all control edges of 'dom'.
296 ResourceMark rm;
297 Arena* arena = Thread::current()->resource_area();
298 Node_List nlist(arena);
299 Unique_Node_List dom_list(arena);
301 dom_list.push(dom);
302 bool only_dominating_controls = false;
304 for (uint next = 0; next < dom_list.size(); next++) {
305 Node* n = dom_list.at(next);
306 if (n == orig_sub)
307 return false; // One of dom's inputs dominated by sub.
308 if (!n->is_CFG() && n->pinned()) {
309 // Check only own control edge for pinned non-control nodes.
310 n = n->find_exact_control(n->in(0));
311 if (n == NULL || n->is_top())
312 return false; // Conservative answer for dead code
313 assert(n->is_CFG(), "expecting control");
314 dom_list.push(n);
315 } else if (n->is_Con() || n->is_Start() || n->is_Root()) {
316 only_dominating_controls = true;
317 } else if (n->is_CFG()) {
318 if (n->dominates(sub, nlist))
319 only_dominating_controls = true;
320 else
321 return false;
322 } else {
323 // First, own control edge.
324 Node* m = n->find_exact_control(n->in(0));
325 if (m != NULL) {
326 if (m->is_top())
327 return false; // Conservative answer for dead code
328 dom_list.push(m);
329 }
330 // Now, the rest of edges.
331 uint cnt = n->req();
332 for (uint i = 1; i < cnt; i++) {
333 m = n->find_exact_control(n->in(i));
334 if (m == NULL || m->is_top())
335 continue;
336 dom_list.push(m);
337 }
338 }
339 }
340 return only_dominating_controls;
341 }
342 }
344 //---------------------detect_ptr_independence---------------------------------
345 // Used by MemNode::find_previous_store to prove that two base
346 // pointers are never equal.
347 // The pointers are accompanied by their associated allocations,
348 // if any, which have been previously discovered by the caller.
349 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
350 Node* p2, AllocateNode* a2,
351 PhaseTransform* phase) {
352 // Attempt to prove that these two pointers cannot be aliased.
353 // They may both manifestly be allocations, and they should differ.
354 // Or, if they are not both allocations, they can be distinct constants.
355 // Otherwise, one is an allocation and the other a pre-existing value.
356 if (a1 == NULL && a2 == NULL) { // neither an allocation
357 return (p1 != p2) && p1->is_Con() && p2->is_Con();
358 } else if (a1 != NULL && a2 != NULL) { // both allocations
359 return (a1 != a2);
360 } else if (a1 != NULL) { // one allocation a1
361 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.)
362 return all_controls_dominate(p2, a1);
363 } else { //(a2 != NULL) // one allocation a2
364 return all_controls_dominate(p1, a2);
365 }
366 return false;
367 }
370 // The logic for reordering loads and stores uses four steps:
371 // (a) Walk carefully past stores and initializations which we
372 // can prove are independent of this load.
373 // (b) Observe that the next memory state makes an exact match
374 // with self (load or store), and locate the relevant store.
375 // (c) Ensure that, if we were to wire self directly to the store,
376 // the optimizer would fold it up somehow.
377 // (d) Do the rewiring, and return, depending on some other part of
378 // the optimizer to fold up the load.
379 // This routine handles steps (a) and (b). Steps (c) and (d) are
380 // specific to loads and stores, so they are handled by the callers.
381 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.)
382 //
383 Node* MemNode::find_previous_store(PhaseTransform* phase) {
384 Node* ctrl = in(MemNode::Control);
385 Node* adr = in(MemNode::Address);
386 intptr_t offset = 0;
387 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
388 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase);
390 if (offset == Type::OffsetBot)
391 return NULL; // cannot unalias unless there are precise offsets
393 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr();
395 intptr_t size_in_bytes = memory_size();
397 Node* mem = in(MemNode::Memory); // start searching here...
399 int cnt = 50; // Cycle limiter
400 for (;;) { // While we can dance past unrelated stores...
401 if (--cnt < 0) break; // Caught in cycle or a complicated dance?
403 if (mem->is_Store()) {
404 Node* st_adr = mem->in(MemNode::Address);
405 intptr_t st_offset = 0;
406 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
407 if (st_base == NULL)
408 break; // inscrutable pointer
409 if (st_offset != offset && st_offset != Type::OffsetBot) {
410 const int MAX_STORE = BytesPerLong;
411 if (st_offset >= offset + size_in_bytes ||
412 st_offset <= offset - MAX_STORE ||
413 st_offset <= offset - mem->as_Store()->memory_size()) {
414 // Success: The offsets are provably independent.
415 // (You may ask, why not just test st_offset != offset and be done?
416 // The answer is that stores of different sizes can co-exist
417 // in the same sequence of RawMem effects. We sometimes initialize
418 // a whole 'tile' of array elements with a single jint or jlong.)
419 mem = mem->in(MemNode::Memory);
420 continue; // (a) advance through independent store memory
421 }
422 }
423 if (st_base != base &&
424 detect_ptr_independence(base, alloc,
425 st_base,
426 AllocateNode::Ideal_allocation(st_base, phase),
427 phase)) {
428 // Success: The bases are provably independent.
429 mem = mem->in(MemNode::Memory);
430 continue; // (a) advance through independent store memory
431 }
433 // (b) At this point, if the bases or offsets do not agree, we lose,
434 // since we have not managed to prove 'this' and 'mem' independent.
435 if (st_base == base && st_offset == offset) {
436 return mem; // let caller handle steps (c), (d)
437 }
439 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
440 InitializeNode* st_init = mem->in(0)->as_Initialize();
441 AllocateNode* st_alloc = st_init->allocation();
442 if (st_alloc == NULL)
443 break; // something degenerated
444 bool known_identical = false;
445 bool known_independent = false;
446 if (alloc == st_alloc)
447 known_identical = true;
448 else if (alloc != NULL)
449 known_independent = true;
450 else if (all_controls_dominate(this, st_alloc))
451 known_independent = true;
453 if (known_independent) {
454 // The bases are provably independent: Either they are
455 // manifestly distinct allocations, or else the control
456 // of this load dominates the store's allocation.
457 int alias_idx = phase->C->get_alias_index(adr_type());
458 if (alias_idx == Compile::AliasIdxRaw) {
459 mem = st_alloc->in(TypeFunc::Memory);
460 } else {
461 mem = st_init->memory(alias_idx);
462 }
463 continue; // (a) advance through independent store memory
464 }
466 // (b) at this point, if we are not looking at a store initializing
467 // the same allocation we are loading from, we lose.
468 if (known_identical) {
469 // From caller, can_see_stored_value will consult find_captured_store.
470 return mem; // let caller handle steps (c), (d)
471 }
473 } else if (addr_t != NULL && addr_t->is_known_instance_field()) {
474 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
475 if (mem->is_Proj() && mem->in(0)->is_Call()) {
476 CallNode *call = mem->in(0)->as_Call();
477 if (!call->may_modify(addr_t, phase)) {
478 mem = call->in(TypeFunc::Memory);
479 continue; // (a) advance through independent call memory
480 }
481 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) {
482 mem = mem->in(0)->in(TypeFunc::Memory);
483 continue; // (a) advance through independent MemBar memory
484 } else if (mem->is_MergeMem()) {
485 int alias_idx = phase->C->get_alias_index(adr_type());
486 mem = mem->as_MergeMem()->memory_at(alias_idx);
487 continue; // (a) advance through independent MergeMem memory
488 }
489 }
491 // Unless there is an explicit 'continue', we must bail out here,
492 // because 'mem' is an inscrutable memory state (e.g., a call).
493 break;
494 }
496 return NULL; // bail out
497 }
499 //----------------------calculate_adr_type-------------------------------------
500 // Helper function. Notices when the given type of address hits top or bottom.
501 // Also, asserts a cross-check of the type against the expected address type.
502 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
503 if (t == Type::TOP) return NULL; // does not touch memory any more?
504 #ifdef PRODUCT
505 cross_check = NULL;
506 #else
507 if (!VerifyAliases || is_error_reported() || Node::in_dump()) cross_check = NULL;
508 #endif
509 const TypePtr* tp = t->isa_ptr();
510 if (tp == NULL) {
511 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
512 return TypePtr::BOTTOM; // touches lots of memory
513 } else {
514 #ifdef ASSERT
515 // %%%% [phh] We don't check the alias index if cross_check is
516 // TypeRawPtr::BOTTOM. Needs to be investigated.
517 if (cross_check != NULL &&
518 cross_check != TypePtr::BOTTOM &&
519 cross_check != TypeRawPtr::BOTTOM) {
520 // Recheck the alias index, to see if it has changed (due to a bug).
521 Compile* C = Compile::current();
522 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
523 "must stay in the original alias category");
524 // The type of the address must be contained in the adr_type,
525 // disregarding "null"-ness.
526 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
527 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
528 assert(cross_check->meet(tp_notnull) == cross_check,
529 "real address must not escape from expected memory type");
530 }
531 #endif
532 return tp;
533 }
534 }
536 //------------------------adr_phi_is_loop_invariant----------------------------
537 // A helper function for Ideal_DU_postCCP to check if a Phi in a counted
538 // loop is loop invariant. Make a quick traversal of Phi and associated
539 // CastPP nodes, looking to see if they are a closed group within the loop.
540 bool MemNode::adr_phi_is_loop_invariant(Node* adr_phi, Node* cast) {
541 // The idea is that the phi-nest must boil down to only CastPP nodes
542 // with the same data. This implies that any path into the loop already
543 // includes such a CastPP, and so the original cast, whatever its input,
544 // must be covered by an equivalent cast, with an earlier control input.
545 ResourceMark rm;
547 // The loop entry input of the phi should be the unique dominating
548 // node for every Phi/CastPP in the loop.
549 Unique_Node_List closure;
550 closure.push(adr_phi->in(LoopNode::EntryControl));
552 // Add the phi node and the cast to the worklist.
553 Unique_Node_List worklist;
554 worklist.push(adr_phi);
555 if( cast != NULL ){
556 if( !cast->is_ConstraintCast() ) return false;
557 worklist.push(cast);
558 }
560 // Begin recursive walk of phi nodes.
561 while( worklist.size() ){
562 // Take a node off the worklist
563 Node *n = worklist.pop();
564 if( !closure.member(n) ){
565 // Add it to the closure.
566 closure.push(n);
567 // Make a sanity check to ensure we don't waste too much time here.
568 if( closure.size() > 20) return false;
569 // This node is OK if:
570 // - it is a cast of an identical value
571 // - or it is a phi node (then we add its inputs to the worklist)
572 // Otherwise, the node is not OK, and we presume the cast is not invariant
573 if( n->is_ConstraintCast() ){
574 worklist.push(n->in(1));
575 } else if( n->is_Phi() ) {
576 for( uint i = 1; i < n->req(); i++ ) {
577 worklist.push(n->in(i));
578 }
579 } else {
580 return false;
581 }
582 }
583 }
585 // Quit when the worklist is empty, and we've found no offending nodes.
586 return true;
587 }
589 //------------------------------Ideal_DU_postCCP-------------------------------
590 // Find any cast-away of null-ness and keep its control. Null cast-aways are
591 // going away in this pass and we need to make this memory op depend on the
592 // gating null check.
593 Node *MemNode::Ideal_DU_postCCP( PhaseCCP *ccp ) {
594 return Ideal_common_DU_postCCP(ccp, this, in(MemNode::Address));
595 }
597 // I tried to leave the CastPP's in. This makes the graph more accurate in
598 // some sense; we get to keep around the knowledge that an oop is not-null
599 // after some test. Alas, the CastPP's interfere with GVN (some values are
600 // the regular oop, some are the CastPP of the oop, all merge at Phi's which
601 // cannot collapse, etc). This cost us 10% on SpecJVM, even when I removed
602 // some of the more trivial cases in the optimizer. Removing more useless
603 // Phi's started allowing Loads to illegally float above null checks. I gave
604 // up on this approach. CNC 10/20/2000
605 // This static method may be called not from MemNode (EncodePNode calls it).
606 // Only the control edge of the node 'n' might be updated.
607 Node *MemNode::Ideal_common_DU_postCCP( PhaseCCP *ccp, Node* n, Node* adr ) {
608 Node *skipped_cast = NULL;
609 // Need a null check? Regular static accesses do not because they are
610 // from constant addresses. Array ops are gated by the range check (which
611 // always includes a NULL check). Just check field ops.
612 if( n->in(MemNode::Control) == NULL ) {
613 // Scan upwards for the highest location we can place this memory op.
614 while( true ) {
615 switch( adr->Opcode() ) {
617 case Op_AddP: // No change to NULL-ness, so peek thru AddP's
618 adr = adr->in(AddPNode::Base);
619 continue;
621 case Op_DecodeN: // No change to NULL-ness, so peek thru
622 adr = adr->in(1);
623 continue;
625 case Op_CastPP:
626 // If the CastPP is useless, just peek on through it.
627 if( ccp->type(adr) == ccp->type(adr->in(1)) ) {
628 // Remember the cast that we've peeked though. If we peek
629 // through more than one, then we end up remembering the highest
630 // one, that is, if in a loop, the one closest to the top.
631 skipped_cast = adr;
632 adr = adr->in(1);
633 continue;
634 }
635 // CastPP is going away in this pass! We need this memory op to be
636 // control-dependent on the test that is guarding the CastPP.
637 ccp->hash_delete(n);
638 n->set_req(MemNode::Control, adr->in(0));
639 ccp->hash_insert(n);
640 return n;
642 case Op_Phi:
643 // Attempt to float above a Phi to some dominating point.
644 if (adr->in(0) != NULL && adr->in(0)->is_CountedLoop()) {
645 // If we've already peeked through a Cast (which could have set the
646 // control), we can't float above a Phi, because the skipped Cast
647 // may not be loop invariant.
648 if (adr_phi_is_loop_invariant(adr, skipped_cast)) {
649 adr = adr->in(1);
650 continue;
651 }
652 }
654 // Intentional fallthrough!
656 // No obvious dominating point. The mem op is pinned below the Phi
657 // by the Phi itself. If the Phi goes away (no true value is merged)
658 // then the mem op can float, but not indefinitely. It must be pinned
659 // behind the controls leading to the Phi.
660 case Op_CheckCastPP:
661 // These usually stick around to change address type, however a
662 // useless one can be elided and we still need to pick up a control edge
663 if (adr->in(0) == NULL) {
664 // This CheckCastPP node has NO control and is likely useless. But we
665 // need check further up the ancestor chain for a control input to keep
666 // the node in place. 4959717.
667 skipped_cast = adr;
668 adr = adr->in(1);
669 continue;
670 }
671 ccp->hash_delete(n);
672 n->set_req(MemNode::Control, adr->in(0));
673 ccp->hash_insert(n);
674 return n;
676 // List of "safe" opcodes; those that implicitly block the memory
677 // op below any null check.
678 case Op_CastX2P: // no null checks on native pointers
679 case Op_Parm: // 'this' pointer is not null
680 case Op_LoadP: // Loading from within a klass
681 case Op_LoadN: // Loading from within a klass
682 case Op_LoadKlass: // Loading from within a klass
683 case Op_LoadNKlass: // Loading from within a klass
684 case Op_ConP: // Loading from a klass
685 case Op_ConN: // Loading from a klass
686 case Op_CreateEx: // Sucking up the guts of an exception oop
687 case Op_Con: // Reading from TLS
688 case Op_CMoveP: // CMoveP is pinned
689 case Op_CMoveN: // CMoveN is pinned
690 break; // No progress
692 case Op_Proj: // Direct call to an allocation routine
693 case Op_SCMemProj: // Memory state from store conditional ops
694 #ifdef ASSERT
695 {
696 assert(adr->as_Proj()->_con == TypeFunc::Parms, "must be return value");
697 const Node* call = adr->in(0);
698 if (call->is_CallJava()) {
699 const CallJavaNode* call_java = call->as_CallJava();
700 const TypeTuple *r = call_java->tf()->range();
701 assert(r->cnt() > TypeFunc::Parms, "must return value");
702 const Type* ret_type = r->field_at(TypeFunc::Parms);
703 assert(ret_type && ret_type->isa_ptr(), "must return pointer");
704 // We further presume that this is one of
705 // new_instance_Java, new_array_Java, or
706 // the like, but do not assert for this.
707 } else if (call->is_Allocate()) {
708 // similar case to new_instance_Java, etc.
709 } else if (!call->is_CallLeaf()) {
710 // Projections from fetch_oop (OSR) are allowed as well.
711 ShouldNotReachHere();
712 }
713 }
714 #endif
715 break;
716 default:
717 ShouldNotReachHere();
718 }
719 break;
720 }
721 }
723 return NULL; // No progress
724 }
727 //=============================================================================
728 uint LoadNode::size_of() const { return sizeof(*this); }
729 uint LoadNode::cmp( const Node &n ) const
730 { return !Type::cmp( _type, ((LoadNode&)n)._type ); }
731 const Type *LoadNode::bottom_type() const { return _type; }
732 uint LoadNode::ideal_reg() const {
733 return Matcher::base2reg[_type->base()];
734 }
736 #ifndef PRODUCT
737 void LoadNode::dump_spec(outputStream *st) const {
738 MemNode::dump_spec(st);
739 if( !Verbose && !WizardMode ) {
740 // standard dump does this in Verbose and WizardMode
741 st->print(" #"); _type->dump_on(st);
742 }
743 }
744 #endif
747 //----------------------------LoadNode::make-----------------------------------
748 // Polymorphic factory method:
749 Node *LoadNode::make( PhaseGVN& gvn, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt ) {
750 Compile* C = gvn.C;
752 // sanity check the alias category against the created node type
753 assert(!(adr_type->isa_oopptr() &&
754 adr_type->offset() == oopDesc::klass_offset_in_bytes()),
755 "use LoadKlassNode instead");
756 assert(!(adr_type->isa_aryptr() &&
757 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
758 "use LoadRangeNode instead");
759 switch (bt) {
760 case T_BOOLEAN:
761 case T_BYTE: return new (C, 3) LoadBNode(ctl, mem, adr, adr_type, rt->is_int() );
762 case T_INT: return new (C, 3) LoadINode(ctl, mem, adr, adr_type, rt->is_int() );
763 case T_CHAR: return new (C, 3) LoadCNode(ctl, mem, adr, adr_type, rt->is_int() );
764 case T_SHORT: return new (C, 3) LoadSNode(ctl, mem, adr, adr_type, rt->is_int() );
765 case T_LONG: return new (C, 3) LoadLNode(ctl, mem, adr, adr_type, rt->is_long() );
766 case T_FLOAT: return new (C, 3) LoadFNode(ctl, mem, adr, adr_type, rt );
767 case T_DOUBLE: return new (C, 3) LoadDNode(ctl, mem, adr, adr_type, rt );
768 case T_ADDRESS: return new (C, 3) LoadPNode(ctl, mem, adr, adr_type, rt->is_ptr() );
769 case T_OBJECT:
770 #ifdef _LP64
771 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
772 Node* load = gvn.transform(new (C, 3) LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop()));
773 return new (C, 2) DecodeNNode(load, load->bottom_type()->make_ptr());
774 } else
775 #endif
776 {
777 assert(!adr->bottom_type()->is_ptr_to_narrowoop(), "should have got back a narrow oop");
778 return new (C, 3) LoadPNode(ctl, mem, adr, adr_type, rt->is_oopptr());
779 }
780 }
781 ShouldNotReachHere();
782 return (LoadNode*)NULL;
783 }
785 LoadLNode* LoadLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt) {
786 bool require_atomic = true;
787 return new (C, 3) LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), require_atomic);
788 }
793 //------------------------------hash-------------------------------------------
794 uint LoadNode::hash() const {
795 // unroll addition of interesting fields
796 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
797 }
799 //---------------------------can_see_stored_value------------------------------
800 // This routine exists to make sure this set of tests is done the same
801 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
802 // will change the graph shape in a way which makes memory alive twice at the
803 // same time (uses the Oracle model of aliasing), then some
804 // LoadXNode::Identity will fold things back to the equivalence-class model
805 // of aliasing.
806 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const {
807 Node* ld_adr = in(MemNode::Address);
809 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
810 Compile::AliasType* atp = tp != NULL ? phase->C->alias_type(tp) : NULL;
811 if (EliminateAutoBox && atp != NULL && atp->index() >= Compile::AliasIdxRaw &&
812 atp->field() != NULL && !atp->field()->is_volatile()) {
813 uint alias_idx = atp->index();
814 bool final = atp->field()->is_final();
815 Node* result = NULL;
816 Node* current = st;
817 // Skip through chains of MemBarNodes checking the MergeMems for
818 // new states for the slice of this load. Stop once any other
819 // kind of node is encountered. Loads from final memory can skip
820 // through any kind of MemBar but normal loads shouldn't skip
821 // through MemBarAcquire since the could allow them to move out of
822 // a synchronized region.
823 while (current->is_Proj()) {
824 int opc = current->in(0)->Opcode();
825 if ((final && opc == Op_MemBarAcquire) ||
826 opc == Op_MemBarRelease || opc == Op_MemBarCPUOrder) {
827 Node* mem = current->in(0)->in(TypeFunc::Memory);
828 if (mem->is_MergeMem()) {
829 MergeMemNode* merge = mem->as_MergeMem();
830 Node* new_st = merge->memory_at(alias_idx);
831 if (new_st == merge->base_memory()) {
832 // Keep searching
833 current = merge->base_memory();
834 continue;
835 }
836 // Save the new memory state for the slice and fall through
837 // to exit.
838 result = new_st;
839 }
840 }
841 break;
842 }
843 if (result != NULL) {
844 st = result;
845 }
846 }
849 // Loop around twice in the case Load -> Initialize -> Store.
850 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
851 for (int trip = 0; trip <= 1; trip++) {
853 if (st->is_Store()) {
854 Node* st_adr = st->in(MemNode::Address);
855 if (!phase->eqv(st_adr, ld_adr)) {
856 // Try harder before giving up... Match raw and non-raw pointers.
857 intptr_t st_off = 0;
858 AllocateNode* alloc = AllocateNode::Ideal_allocation(st_adr, phase, st_off);
859 if (alloc == NULL) return NULL;
860 intptr_t ld_off = 0;
861 AllocateNode* allo2 = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
862 if (alloc != allo2) return NULL;
863 if (ld_off != st_off) return NULL;
864 // At this point we have proven something like this setup:
865 // A = Allocate(...)
866 // L = LoadQ(, AddP(CastPP(, A.Parm),, #Off))
867 // S = StoreQ(, AddP(, A.Parm , #Off), V)
868 // (Actually, we haven't yet proven the Q's are the same.)
869 // In other words, we are loading from a casted version of
870 // the same pointer-and-offset that we stored to.
871 // Thus, we are able to replace L by V.
872 }
873 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
874 if (store_Opcode() != st->Opcode())
875 return NULL;
876 return st->in(MemNode::ValueIn);
877 }
879 intptr_t offset = 0; // scratch
881 // A load from a freshly-created object always returns zero.
882 // (This can happen after LoadNode::Ideal resets the load's memory input
883 // to find_captured_store, which returned InitializeNode::zero_memory.)
884 if (st->is_Proj() && st->in(0)->is_Allocate() &&
885 st->in(0) == AllocateNode::Ideal_allocation(ld_adr, phase, offset) &&
886 offset >= st->in(0)->as_Allocate()->minimum_header_size()) {
887 // return a zero value for the load's basic type
888 // (This is one of the few places where a generic PhaseTransform
889 // can create new nodes. Think of it as lazily manifesting
890 // virtually pre-existing constants.)
891 return phase->zerocon(memory_type());
892 }
894 // A load from an initialization barrier can match a captured store.
895 if (st->is_Proj() && st->in(0)->is_Initialize()) {
896 InitializeNode* init = st->in(0)->as_Initialize();
897 AllocateNode* alloc = init->allocation();
898 if (alloc != NULL &&
899 alloc == AllocateNode::Ideal_allocation(ld_adr, phase, offset)) {
900 // examine a captured store value
901 st = init->find_captured_store(offset, memory_size(), phase);
902 if (st != NULL)
903 continue; // take one more trip around
904 }
905 }
907 break;
908 }
910 return NULL;
911 }
913 //----------------------is_instance_field_load_with_local_phi------------------
914 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
915 if( in(MemNode::Memory)->is_Phi() && in(MemNode::Memory)->in(0) == ctrl &&
916 in(MemNode::Address)->is_AddP() ) {
917 const TypeOopPtr* t_oop = in(MemNode::Address)->bottom_type()->isa_oopptr();
918 // Only instances.
919 if( t_oop != NULL && t_oop->is_known_instance_field() &&
920 t_oop->offset() != Type::OffsetBot &&
921 t_oop->offset() != Type::OffsetTop) {
922 return true;
923 }
924 }
925 return false;
926 }
928 //------------------------------Identity---------------------------------------
929 // Loads are identity if previous store is to same address
930 Node *LoadNode::Identity( PhaseTransform *phase ) {
931 // If the previous store-maker is the right kind of Store, and the store is
932 // to the same address, then we are equal to the value stored.
933 Node* mem = in(MemNode::Memory);
934 Node* value = can_see_stored_value(mem, phase);
935 if( value ) {
936 // byte, short & char stores truncate naturally.
937 // A load has to load the truncated value which requires
938 // some sort of masking operation and that requires an
939 // Ideal call instead of an Identity call.
940 if (memory_size() < BytesPerInt) {
941 // If the input to the store does not fit with the load's result type,
942 // it must be truncated via an Ideal call.
943 if (!phase->type(value)->higher_equal(phase->type(this)))
944 return this;
945 }
946 // (This works even when value is a Con, but LoadNode::Value
947 // usually runs first, producing the singleton type of the Con.)
948 return value;
949 }
951 // Search for an existing data phi which was generated before for the same
952 // instance's field to avoid infinite genertion of phis in a loop.
953 Node *region = mem->in(0);
954 if (is_instance_field_load_with_local_phi(region)) {
955 const TypePtr *addr_t = in(MemNode::Address)->bottom_type()->isa_ptr();
956 int this_index = phase->C->get_alias_index(addr_t);
957 int this_offset = addr_t->offset();
958 int this_id = addr_t->is_oopptr()->instance_id();
959 const Type* this_type = bottom_type();
960 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
961 Node* phi = region->fast_out(i);
962 if (phi->is_Phi() && phi != mem &&
963 phi->as_Phi()->is_same_inst_field(this_type, this_id, this_index, this_offset)) {
964 return phi;
965 }
966 }
967 }
969 return this;
970 }
973 // Returns true if the AliasType refers to the field that holds the
974 // cached box array. Currently only handles the IntegerCache case.
975 static bool is_autobox_cache(Compile::AliasType* atp) {
976 if (atp != NULL && atp->field() != NULL) {
977 ciField* field = atp->field();
978 ciSymbol* klass = field->holder()->name();
979 if (field->name() == ciSymbol::cache_field_name() &&
980 field->holder()->uses_default_loader() &&
981 klass == ciSymbol::java_lang_Integer_IntegerCache()) {
982 return true;
983 }
984 }
985 return false;
986 }
988 // Fetch the base value in the autobox array
989 static bool fetch_autobox_base(Compile::AliasType* atp, int& cache_offset) {
990 if (atp != NULL && atp->field() != NULL) {
991 ciField* field = atp->field();
992 ciSymbol* klass = field->holder()->name();
993 if (field->name() == ciSymbol::cache_field_name() &&
994 field->holder()->uses_default_loader() &&
995 klass == ciSymbol::java_lang_Integer_IntegerCache()) {
996 assert(field->is_constant(), "what?");
997 ciObjArray* array = field->constant_value().as_object()->as_obj_array();
998 // Fetch the box object at the base of the array and get its value
999 ciInstance* box = array->obj_at(0)->as_instance();
1000 ciInstanceKlass* ik = box->klass()->as_instance_klass();
1001 if (ik->nof_nonstatic_fields() == 1) {
1002 // This should be true nonstatic_field_at requires calling
1003 // nof_nonstatic_fields so check it anyway
1004 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1005 cache_offset = c.as_int();
1006 }
1007 return true;
1008 }
1009 }
1010 return false;
1011 }
1013 // Returns true if the AliasType refers to the value field of an
1014 // autobox object. Currently only handles Integer.
1015 static bool is_autobox_object(Compile::AliasType* atp) {
1016 if (atp != NULL && atp->field() != NULL) {
1017 ciField* field = atp->field();
1018 ciSymbol* klass = field->holder()->name();
1019 if (field->name() == ciSymbol::value_name() &&
1020 field->holder()->uses_default_loader() &&
1021 klass == ciSymbol::java_lang_Integer()) {
1022 return true;
1023 }
1024 }
1025 return false;
1026 }
1029 // We're loading from an object which has autobox behaviour.
1030 // If this object is result of a valueOf call we'll have a phi
1031 // merging a newly allocated object and a load from the cache.
1032 // We want to replace this load with the original incoming
1033 // argument to the valueOf call.
1034 Node* LoadNode::eliminate_autobox(PhaseGVN* phase) {
1035 Node* base = in(Address)->in(AddPNode::Base);
1036 if (base->is_Phi() && base->req() == 3) {
1037 AllocateNode* allocation = NULL;
1038 int allocation_index = -1;
1039 int load_index = -1;
1040 for (uint i = 1; i < base->req(); i++) {
1041 allocation = AllocateNode::Ideal_allocation(base->in(i), phase);
1042 if (allocation != NULL) {
1043 allocation_index = i;
1044 load_index = 3 - allocation_index;
1045 break;
1046 }
1047 }
1048 LoadNode* load = NULL;
1049 if (allocation != NULL && base->in(load_index)->is_Load()) {
1050 load = base->in(load_index)->as_Load();
1051 }
1052 if (load != NULL && in(Memory)->is_Phi() && in(Memory)->in(0) == base->in(0)) {
1053 // Push the loads from the phi that comes from valueOf up
1054 // through it to allow elimination of the loads and the recovery
1055 // of the original value.
1056 Node* mem_phi = in(Memory);
1057 Node* offset = in(Address)->in(AddPNode::Offset);
1059 Node* in1 = clone();
1060 Node* in1_addr = in1->in(Address)->clone();
1061 in1_addr->set_req(AddPNode::Base, base->in(allocation_index));
1062 in1_addr->set_req(AddPNode::Address, base->in(allocation_index));
1063 in1_addr->set_req(AddPNode::Offset, offset);
1064 in1->set_req(0, base->in(allocation_index));
1065 in1->set_req(Address, in1_addr);
1066 in1->set_req(Memory, mem_phi->in(allocation_index));
1068 Node* in2 = clone();
1069 Node* in2_addr = in2->in(Address)->clone();
1070 in2_addr->set_req(AddPNode::Base, base->in(load_index));
1071 in2_addr->set_req(AddPNode::Address, base->in(load_index));
1072 in2_addr->set_req(AddPNode::Offset, offset);
1073 in2->set_req(0, base->in(load_index));
1074 in2->set_req(Address, in2_addr);
1075 in2->set_req(Memory, mem_phi->in(load_index));
1077 in1_addr = phase->transform(in1_addr);
1078 in1 = phase->transform(in1);
1079 in2_addr = phase->transform(in2_addr);
1080 in2 = phase->transform(in2);
1082 PhiNode* result = PhiNode::make_blank(base->in(0), this);
1083 result->set_req(allocation_index, in1);
1084 result->set_req(load_index, in2);
1085 return result;
1086 }
1087 } else if (base->is_Load()) {
1088 // Eliminate the load of Integer.value for integers from the cache
1089 // array by deriving the value from the index into the array.
1090 // Capture the offset of the load and then reverse the computation.
1091 Node* load_base = base->in(Address)->in(AddPNode::Base);
1092 if (load_base != NULL) {
1093 Compile::AliasType* atp = phase->C->alias_type(load_base->adr_type());
1094 intptr_t cache_offset;
1095 int shift = -1;
1096 Node* cache = NULL;
1097 if (is_autobox_cache(atp)) {
1098 shift = exact_log2(type2aelembytes(T_OBJECT));
1099 cache = AddPNode::Ideal_base_and_offset(load_base->in(Address), phase, cache_offset);
1100 }
1101 if (cache != NULL && base->in(Address)->is_AddP()) {
1102 Node* elements[4];
1103 int count = base->in(Address)->as_AddP()->unpack_offsets(elements, ARRAY_SIZE(elements));
1104 int cache_low;
1105 if (count > 0 && fetch_autobox_base(atp, cache_low)) {
1106 int offset = arrayOopDesc::base_offset_in_bytes(memory_type()) - (cache_low << shift);
1107 // Add up all the offsets making of the address of the load
1108 Node* result = elements[0];
1109 for (int i = 1; i < count; i++) {
1110 result = phase->transform(new (phase->C, 3) AddXNode(result, elements[i]));
1111 }
1112 // Remove the constant offset from the address and then
1113 // remove the scaling of the offset to recover the original index.
1114 result = phase->transform(new (phase->C, 3) AddXNode(result, phase->MakeConX(-offset)));
1115 if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) {
1116 // Peel the shift off directly but wrap it in a dummy node
1117 // since Ideal can't return existing nodes
1118 result = new (phase->C, 3) RShiftXNode(result->in(1), phase->intcon(0));
1119 } else {
1120 result = new (phase->C, 3) RShiftXNode(result, phase->intcon(shift));
1121 }
1122 #ifdef _LP64
1123 result = new (phase->C, 2) ConvL2INode(phase->transform(result));
1124 #endif
1125 return result;
1126 }
1127 }
1128 }
1129 }
1130 return NULL;
1131 }
1133 //------------------------------split_through_phi------------------------------
1134 // Split instance field load through Phi.
1135 Node *LoadNode::split_through_phi(PhaseGVN *phase) {
1136 Node* mem = in(MemNode::Memory);
1137 Node* address = in(MemNode::Address);
1138 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1139 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1141 assert(mem->is_Phi() && (t_oop != NULL) &&
1142 t_oop->is_known_instance_field(), "invalide conditions");
1144 Node *region = mem->in(0);
1145 if (region == NULL) {
1146 return NULL; // Wait stable graph
1147 }
1148 uint cnt = mem->req();
1149 for( uint i = 1; i < cnt; i++ ) {
1150 Node *in = mem->in(i);
1151 if( in == NULL ) {
1152 return NULL; // Wait stable graph
1153 }
1154 }
1155 // Check for loop invariant.
1156 if (cnt == 3) {
1157 for( uint i = 1; i < cnt; i++ ) {
1158 Node *in = mem->in(i);
1159 Node* m = MemNode::optimize_memory_chain(in, addr_t, phase);
1160 if (m == mem) {
1161 set_req(MemNode::Memory, mem->in(cnt - i)); // Skip this phi.
1162 return this;
1163 }
1164 }
1165 }
1166 // Split through Phi (see original code in loopopts.cpp).
1167 assert(phase->C->have_alias_type(addr_t), "instance should have alias type");
1169 // Do nothing here if Identity will find a value
1170 // (to avoid infinite chain of value phis generation).
1171 if ( !phase->eqv(this, this->Identity(phase)) )
1172 return NULL;
1174 // Skip the split if the region dominates some control edge of the address.
1175 if (cnt == 3 && !MemNode::all_controls_dominate(address, region))
1176 return NULL;
1178 const Type* this_type = this->bottom_type();
1179 int this_index = phase->C->get_alias_index(addr_t);
1180 int this_offset = addr_t->offset();
1181 int this_iid = addr_t->is_oopptr()->instance_id();
1182 int wins = 0;
1183 PhaseIterGVN *igvn = phase->is_IterGVN();
1184 Node *phi = new (igvn->C, region->req()) PhiNode(region, this_type, NULL, this_iid, this_index, this_offset);
1185 for( uint i = 1; i < region->req(); i++ ) {
1186 Node *x;
1187 Node* the_clone = NULL;
1188 if( region->in(i) == phase->C->top() ) {
1189 x = phase->C->top(); // Dead path? Use a dead data op
1190 } else {
1191 x = this->clone(); // Else clone up the data op
1192 the_clone = x; // Remember for possible deletion.
1193 // Alter data node to use pre-phi inputs
1194 if( this->in(0) == region ) {
1195 x->set_req( 0, region->in(i) );
1196 } else {
1197 x->set_req( 0, NULL );
1198 }
1199 for( uint j = 1; j < this->req(); j++ ) {
1200 Node *in = this->in(j);
1201 if( in->is_Phi() && in->in(0) == region )
1202 x->set_req( j, in->in(i) ); // Use pre-Phi input for the clone
1203 }
1204 }
1205 // Check for a 'win' on some paths
1206 const Type *t = x->Value(igvn);
1208 bool singleton = t->singleton();
1210 // See comments in PhaseIdealLoop::split_thru_phi().
1211 if( singleton && t == Type::TOP ) {
1212 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1213 }
1215 if( singleton ) {
1216 wins++;
1217 x = igvn->makecon(t);
1218 } else {
1219 // We now call Identity to try to simplify the cloned node.
1220 // Note that some Identity methods call phase->type(this).
1221 // Make sure that the type array is big enough for
1222 // our new node, even though we may throw the node away.
1223 // (This tweaking with igvn only works because x is a new node.)
1224 igvn->set_type(x, t);
1225 Node *y = x->Identity(igvn);
1226 if( y != x ) {
1227 wins++;
1228 x = y;
1229 } else {
1230 y = igvn->hash_find(x);
1231 if( y ) {
1232 wins++;
1233 x = y;
1234 } else {
1235 // Else x is a new node we are keeping
1236 // We do not need register_new_node_with_optimizer
1237 // because set_type has already been called.
1238 igvn->_worklist.push(x);
1239 }
1240 }
1241 }
1242 if (x != the_clone && the_clone != NULL)
1243 igvn->remove_dead_node(the_clone);
1244 phi->set_req(i, x);
1245 }
1246 if( wins > 0 ) {
1247 // Record Phi
1248 igvn->register_new_node_with_optimizer(phi);
1249 return phi;
1250 }
1251 igvn->remove_dead_node(phi);
1252 return NULL;
1253 }
1255 //------------------------------Ideal------------------------------------------
1256 // If the load is from Field memory and the pointer is non-null, we can
1257 // zero out the control input.
1258 // If the offset is constant and the base is an object allocation,
1259 // try to hook me up to the exact initializing store.
1260 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1261 Node* p = MemNode::Ideal_common(phase, can_reshape);
1262 if (p) return (p == NodeSentinel) ? NULL : p;
1264 Node* ctrl = in(MemNode::Control);
1265 Node* address = in(MemNode::Address);
1267 // Skip up past a SafePoint control. Cannot do this for Stores because
1268 // pointer stores & cardmarks must stay on the same side of a SafePoint.
1269 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint &&
1270 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw ) {
1271 ctrl = ctrl->in(0);
1272 set_req(MemNode::Control,ctrl);
1273 }
1275 // Check for useless control edge in some common special cases
1276 if (in(MemNode::Control) != NULL) {
1277 intptr_t ignore = 0;
1278 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1279 if (base != NULL
1280 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1281 && all_controls_dominate(base, phase->C->start())) {
1282 // A method-invariant, non-null address (constant or 'this' argument).
1283 set_req(MemNode::Control, NULL);
1284 }
1285 }
1287 if (EliminateAutoBox && can_reshape && in(Address)->is_AddP()) {
1288 Node* base = in(Address)->in(AddPNode::Base);
1289 if (base != NULL) {
1290 Compile::AliasType* atp = phase->C->alias_type(adr_type());
1291 if (is_autobox_object(atp)) {
1292 Node* result = eliminate_autobox(phase);
1293 if (result != NULL) return result;
1294 }
1295 }
1296 }
1298 Node* mem = in(MemNode::Memory);
1299 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1301 if (addr_t != NULL) {
1302 // try to optimize our memory input
1303 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, phase);
1304 if (opt_mem != mem) {
1305 set_req(MemNode::Memory, opt_mem);
1306 return this;
1307 }
1308 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1309 if (can_reshape && opt_mem->is_Phi() &&
1310 (t_oop != NULL) && t_oop->is_known_instance_field()) {
1311 // Split instance field load through Phi.
1312 Node* result = split_through_phi(phase);
1313 if (result != NULL) return result;
1314 }
1315 }
1317 // Check for prior store with a different base or offset; make Load
1318 // independent. Skip through any number of them. Bail out if the stores
1319 // are in an endless dead cycle and report no progress. This is a key
1320 // transform for Reflection. However, if after skipping through the Stores
1321 // we can't then fold up against a prior store do NOT do the transform as
1322 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
1323 // array memory alive twice: once for the hoisted Load and again after the
1324 // bypassed Store. This situation only works if EVERYBODY who does
1325 // anti-dependence work knows how to bypass. I.e. we need all
1326 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
1327 // the alias index stuff. So instead, peek through Stores and IFF we can
1328 // fold up, do so.
1329 Node* prev_mem = find_previous_store(phase);
1330 // Steps (a), (b): Walk past independent stores to find an exact match.
1331 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) {
1332 // (c) See if we can fold up on the spot, but don't fold up here.
1333 // Fold-up might require truncation (for LoadB/LoadS/LoadC) or
1334 // just return a prior value, which is done by Identity calls.
1335 if (can_see_stored_value(prev_mem, phase)) {
1336 // Make ready for step (d):
1337 set_req(MemNode::Memory, prev_mem);
1338 return this;
1339 }
1340 }
1342 return NULL; // No further progress
1343 }
1345 // Helper to recognize certain Klass fields which are invariant across
1346 // some group of array types (e.g., int[] or all T[] where T < Object).
1347 const Type*
1348 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1349 ciKlass* klass) const {
1350 if (tkls->offset() == Klass::modifier_flags_offset_in_bytes() + (int)sizeof(oopDesc)) {
1351 // The field is Klass::_modifier_flags. Return its (constant) value.
1352 // (Folds up the 2nd indirection in aClassConstant.getModifiers().)
1353 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags");
1354 return TypeInt::make(klass->modifier_flags());
1355 }
1356 if (tkls->offset() == Klass::access_flags_offset_in_bytes() + (int)sizeof(oopDesc)) {
1357 // The field is Klass::_access_flags. Return its (constant) value.
1358 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1359 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags");
1360 return TypeInt::make(klass->access_flags());
1361 }
1362 if (tkls->offset() == Klass::layout_helper_offset_in_bytes() + (int)sizeof(oopDesc)) {
1363 // The field is Klass::_layout_helper. Return its constant value if known.
1364 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper");
1365 return TypeInt::make(klass->layout_helper());
1366 }
1368 // No match.
1369 return NULL;
1370 }
1372 //------------------------------Value-----------------------------------------
1373 const Type *LoadNode::Value( PhaseTransform *phase ) const {
1374 // Either input is TOP ==> the result is TOP
1375 Node* mem = in(MemNode::Memory);
1376 const Type *t1 = phase->type(mem);
1377 if (t1 == Type::TOP) return Type::TOP;
1378 Node* adr = in(MemNode::Address);
1379 const TypePtr* tp = phase->type(adr)->isa_ptr();
1380 if (tp == NULL || tp->empty()) return Type::TOP;
1381 int off = tp->offset();
1382 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
1384 // Try to guess loaded type from pointer type
1385 if (tp->base() == Type::AryPtr) {
1386 const Type *t = tp->is_aryptr()->elem();
1387 // Don't do this for integer types. There is only potential profit if
1388 // the element type t is lower than _type; that is, for int types, if _type is
1389 // more restrictive than t. This only happens here if one is short and the other
1390 // char (both 16 bits), and in those cases we've made an intentional decision
1391 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
1392 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
1393 //
1394 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
1395 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
1396 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
1397 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
1398 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
1399 // In fact, that could have been the original type of p1, and p1 could have
1400 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
1401 // expression (LShiftL quux 3) independently optimized to the constant 8.
1402 if ((t->isa_int() == NULL) && (t->isa_long() == NULL)
1403 && Opcode() != Op_LoadKlass) {
1404 // t might actually be lower than _type, if _type is a unique
1405 // concrete subclass of abstract class t.
1406 // Make sure the reference is not into the header, by comparing
1407 // the offset against the offset of the start of the array's data.
1408 // Different array types begin at slightly different offsets (12 vs. 16).
1409 // We choose T_BYTE as an example base type that is least restrictive
1410 // as to alignment, which will therefore produce the smallest
1411 // possible base offset.
1412 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
1413 if ((uint)off >= (uint)min_base_off) { // is the offset beyond the header?
1414 const Type* jt = t->join(_type);
1415 // In any case, do not allow the join, per se, to empty out the type.
1416 if (jt->empty() && !t->empty()) {
1417 // This can happen if a interface-typed array narrows to a class type.
1418 jt = _type;
1419 }
1421 if (EliminateAutoBox) {
1422 // The pointers in the autobox arrays are always non-null
1423 Node* base = in(Address)->in(AddPNode::Base);
1424 if (base != NULL) {
1425 Compile::AliasType* atp = phase->C->alias_type(base->adr_type());
1426 if (is_autobox_cache(atp)) {
1427 return jt->join(TypePtr::NOTNULL)->is_ptr();
1428 }
1429 }
1430 }
1431 return jt;
1432 }
1433 }
1434 } else if (tp->base() == Type::InstPtr) {
1435 assert( off != Type::OffsetBot ||
1436 // arrays can be cast to Objects
1437 tp->is_oopptr()->klass()->is_java_lang_Object() ||
1438 // unsafe field access may not have a constant offset
1439 phase->C->has_unsafe_access(),
1440 "Field accesses must be precise" );
1441 // For oop loads, we expect the _type to be precise
1442 } else if (tp->base() == Type::KlassPtr) {
1443 assert( off != Type::OffsetBot ||
1444 // arrays can be cast to Objects
1445 tp->is_klassptr()->klass()->is_java_lang_Object() ||
1446 // also allow array-loading from the primary supertype
1447 // array during subtype checks
1448 Opcode() == Op_LoadKlass,
1449 "Field accesses must be precise" );
1450 // For klass/static loads, we expect the _type to be precise
1451 }
1453 const TypeKlassPtr *tkls = tp->isa_klassptr();
1454 if (tkls != NULL && !StressReflectiveCode) {
1455 ciKlass* klass = tkls->klass();
1456 if (klass->is_loaded() && tkls->klass_is_exact()) {
1457 // We are loading a field from a Klass metaobject whose identity
1458 // is known at compile time (the type is "exact" or "precise").
1459 // Check for fields we know are maintained as constants by the VM.
1460 if (tkls->offset() == Klass::super_check_offset_offset_in_bytes() + (int)sizeof(oopDesc)) {
1461 // The field is Klass::_super_check_offset. Return its (constant) value.
1462 // (Folds up type checking code.)
1463 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
1464 return TypeInt::make(klass->super_check_offset());
1465 }
1466 // Compute index into primary_supers array
1467 juint depth = (tkls->offset() - (Klass::primary_supers_offset_in_bytes() + (int)sizeof(oopDesc))) / sizeof(klassOop);
1468 // Check for overflowing; use unsigned compare to handle the negative case.
1469 if( depth < ciKlass::primary_super_limit() ) {
1470 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1471 // (Folds up type checking code.)
1472 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1473 ciKlass *ss = klass->super_of_depth(depth);
1474 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1475 }
1476 const Type* aift = load_array_final_field(tkls, klass);
1477 if (aift != NULL) return aift;
1478 if (tkls->offset() == in_bytes(arrayKlass::component_mirror_offset()) + (int)sizeof(oopDesc)
1479 && klass->is_array_klass()) {
1480 // The field is arrayKlass::_component_mirror. Return its (constant) value.
1481 // (Folds up aClassConstant.getComponentType, common in Arrays.copyOf.)
1482 assert(Opcode() == Op_LoadP, "must load an oop from _component_mirror");
1483 return TypeInstPtr::make(klass->as_array_klass()->component_mirror());
1484 }
1485 if (tkls->offset() == Klass::java_mirror_offset_in_bytes() + (int)sizeof(oopDesc)) {
1486 // The field is Klass::_java_mirror. Return its (constant) value.
1487 // (Folds up the 2nd indirection in anObjConstant.getClass().)
1488 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
1489 return TypeInstPtr::make(klass->java_mirror());
1490 }
1491 }
1493 // We can still check if we are loading from the primary_supers array at a
1494 // shallow enough depth. Even though the klass is not exact, entries less
1495 // than or equal to its super depth are correct.
1496 if (klass->is_loaded() ) {
1497 ciType *inner = klass->klass();
1498 while( inner->is_obj_array_klass() )
1499 inner = inner->as_obj_array_klass()->base_element_type();
1500 if( inner->is_instance_klass() &&
1501 !inner->as_instance_klass()->flags().is_interface() ) {
1502 // Compute index into primary_supers array
1503 juint depth = (tkls->offset() - (Klass::primary_supers_offset_in_bytes() + (int)sizeof(oopDesc))) / sizeof(klassOop);
1504 // Check for overflowing; use unsigned compare to handle the negative case.
1505 if( depth < ciKlass::primary_super_limit() &&
1506 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case
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 }
1514 }
1516 // If the type is enough to determine that the thing is not an array,
1517 // we can give the layout_helper a positive interval type.
1518 // This will help short-circuit some reflective code.
1519 if (tkls->offset() == Klass::layout_helper_offset_in_bytes() + (int)sizeof(oopDesc)
1520 && !klass->is_array_klass() // not directly typed as an array
1521 && !klass->is_interface() // specifically not Serializable & Cloneable
1522 && !klass->is_java_lang_Object() // not the supertype of all T[]
1523 ) {
1524 // Note: When interfaces are reliable, we can narrow the interface
1525 // test to (klass != Serializable && klass != Cloneable).
1526 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
1527 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
1528 // The key property of this type is that it folds up tests
1529 // for array-ness, since it proves that the layout_helper is positive.
1530 // Thus, a generic value like the basic object layout helper works fine.
1531 return TypeInt::make(min_size, max_jint, Type::WidenMin);
1532 }
1533 }
1535 // If we are loading from a freshly-allocated object, produce a zero,
1536 // if the load is provably beyond the header of the object.
1537 // (Also allow a variable load from a fresh array to produce zero.)
1538 if (ReduceFieldZeroing) {
1539 Node* value = can_see_stored_value(mem,phase);
1540 if (value != NULL && value->is_Con())
1541 return value->bottom_type();
1542 }
1544 const TypeOopPtr *tinst = tp->isa_oopptr();
1545 if (tinst != NULL && tinst->is_known_instance_field()) {
1546 // If we have an instance type and our memory input is the
1547 // programs's initial memory state, there is no matching store,
1548 // so just return a zero of the appropriate type
1549 Node *mem = in(MemNode::Memory);
1550 if (mem->is_Parm() && mem->in(0)->is_Start()) {
1551 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
1552 return Type::get_zero_type(_type->basic_type());
1553 }
1554 }
1555 return _type;
1556 }
1558 //------------------------------match_edge-------------------------------------
1559 // Do we Match on this edge index or not? Match only the address.
1560 uint LoadNode::match_edge(uint idx) const {
1561 return idx == MemNode::Address;
1562 }
1564 //--------------------------LoadBNode::Ideal--------------------------------------
1565 //
1566 // If the previous store is to the same address as this load,
1567 // and the value stored was larger than a byte, replace this load
1568 // with the value stored truncated to a byte. If no truncation is
1569 // needed, the replacement is done in LoadNode::Identity().
1570 //
1571 Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1572 Node* mem = in(MemNode::Memory);
1573 Node* value = can_see_stored_value(mem,phase);
1574 if( value && !phase->type(value)->higher_equal( _type ) ) {
1575 Node *result = phase->transform( new (phase->C, 3) LShiftINode(value, phase->intcon(24)) );
1576 return new (phase->C, 3) RShiftINode(result, phase->intcon(24));
1577 }
1578 // Identity call will handle the case where truncation is not needed.
1579 return LoadNode::Ideal(phase, can_reshape);
1580 }
1582 //--------------------------LoadCNode::Ideal--------------------------------------
1583 //
1584 // If the previous store is to the same address as this load,
1585 // and the value stored was larger than a char, replace this load
1586 // with the value stored truncated to a char. If no truncation is
1587 // needed, the replacement is done in LoadNode::Identity().
1588 //
1589 Node *LoadCNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1590 Node* mem = in(MemNode::Memory);
1591 Node* value = can_see_stored_value(mem,phase);
1592 if( value && !phase->type(value)->higher_equal( _type ) )
1593 return new (phase->C, 3) AndINode(value,phase->intcon(0xFFFF));
1594 // Identity call will handle the case where truncation is not needed.
1595 return LoadNode::Ideal(phase, can_reshape);
1596 }
1598 //--------------------------LoadSNode::Ideal--------------------------------------
1599 //
1600 // If the previous store is to the same address as this load,
1601 // and the value stored was larger than a short, replace this load
1602 // with the value stored truncated to a short. If no truncation is
1603 // needed, the replacement is done in LoadNode::Identity().
1604 //
1605 Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1606 Node* mem = in(MemNode::Memory);
1607 Node* value = can_see_stored_value(mem,phase);
1608 if( value && !phase->type(value)->higher_equal( _type ) ) {
1609 Node *result = phase->transform( new (phase->C, 3) LShiftINode(value, phase->intcon(16)) );
1610 return new (phase->C, 3) RShiftINode(result, phase->intcon(16));
1611 }
1612 // Identity call will handle the case where truncation is not needed.
1613 return LoadNode::Ideal(phase, can_reshape);
1614 }
1616 //=============================================================================
1617 //----------------------------LoadKlassNode::make------------------------------
1618 // Polymorphic factory method:
1619 Node *LoadKlassNode::make( PhaseGVN& gvn, Node *mem, Node *adr, const TypePtr* at, const TypeKlassPtr *tk ) {
1620 Compile* C = gvn.C;
1621 Node *ctl = NULL;
1622 // sanity check the alias category against the created node type
1623 const TypeOopPtr *adr_type = adr->bottom_type()->isa_oopptr();
1624 assert(adr_type != NULL, "expecting TypeOopPtr");
1625 #ifdef _LP64
1626 if (adr_type->is_ptr_to_narrowoop()) {
1627 Node* load_klass = gvn.transform(new (C, 3) LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowoop()));
1628 return new (C, 2) DecodeNNode(load_klass, load_klass->bottom_type()->make_ptr());
1629 }
1630 #endif
1631 assert(!adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
1632 return new (C, 3) LoadKlassNode(ctl, mem, adr, at, tk);
1633 }
1635 //------------------------------Value------------------------------------------
1636 const Type *LoadKlassNode::Value( PhaseTransform *phase ) const {
1637 return klass_value_common(phase);
1638 }
1640 const Type *LoadNode::klass_value_common( PhaseTransform *phase ) const {
1641 // Either input is TOP ==> the result is TOP
1642 const Type *t1 = phase->type( in(MemNode::Memory) );
1643 if (t1 == Type::TOP) return Type::TOP;
1644 Node *adr = in(MemNode::Address);
1645 const Type *t2 = phase->type( adr );
1646 if (t2 == Type::TOP) return Type::TOP;
1647 const TypePtr *tp = t2->is_ptr();
1648 if (TypePtr::above_centerline(tp->ptr()) ||
1649 tp->ptr() == TypePtr::Null) return Type::TOP;
1651 // Return a more precise klass, if possible
1652 const TypeInstPtr *tinst = tp->isa_instptr();
1653 if (tinst != NULL) {
1654 ciInstanceKlass* ik = tinst->klass()->as_instance_klass();
1655 int offset = tinst->offset();
1656 if (ik == phase->C->env()->Class_klass()
1657 && (offset == java_lang_Class::klass_offset_in_bytes() ||
1658 offset == java_lang_Class::array_klass_offset_in_bytes())) {
1659 // We are loading a special hidden field from a Class mirror object,
1660 // the field which points to the VM's Klass metaobject.
1661 ciType* t = tinst->java_mirror_type();
1662 // java_mirror_type returns non-null for compile-time Class constants.
1663 if (t != NULL) {
1664 // constant oop => constant klass
1665 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
1666 return TypeKlassPtr::make(ciArrayKlass::make(t));
1667 }
1668 if (!t->is_klass()) {
1669 // a primitive Class (e.g., int.class) has NULL for a klass field
1670 return TypePtr::NULL_PTR;
1671 }
1672 // (Folds up the 1st indirection in aClassConstant.getModifiers().)
1673 return TypeKlassPtr::make(t->as_klass());
1674 }
1675 // non-constant mirror, so we can't tell what's going on
1676 }
1677 if( !ik->is_loaded() )
1678 return _type; // Bail out if not loaded
1679 if (offset == oopDesc::klass_offset_in_bytes()) {
1680 if (tinst->klass_is_exact()) {
1681 return TypeKlassPtr::make(ik);
1682 }
1683 // See if we can become precise: no subklasses and no interface
1684 // (Note: We need to support verified interfaces.)
1685 if (!ik->is_interface() && !ik->has_subklass()) {
1686 //assert(!UseExactTypes, "this code should be useless with exact types");
1687 // Add a dependence; if any subclass added we need to recompile
1688 if (!ik->is_final()) {
1689 // %%% should use stronger assert_unique_concrete_subtype instead
1690 phase->C->dependencies()->assert_leaf_type(ik);
1691 }
1692 // Return precise klass
1693 return TypeKlassPtr::make(ik);
1694 }
1696 // Return root of possible klass
1697 return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/);
1698 }
1699 }
1701 // Check for loading klass from an array
1702 const TypeAryPtr *tary = tp->isa_aryptr();
1703 if( tary != NULL ) {
1704 ciKlass *tary_klass = tary->klass();
1705 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP
1706 && tary->offset() == oopDesc::klass_offset_in_bytes()) {
1707 if (tary->klass_is_exact()) {
1708 return TypeKlassPtr::make(tary_klass);
1709 }
1710 ciArrayKlass *ak = tary->klass()->as_array_klass();
1711 // If the klass is an object array, we defer the question to the
1712 // array component klass.
1713 if( ak->is_obj_array_klass() ) {
1714 assert( ak->is_loaded(), "" );
1715 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass();
1716 if( base_k->is_loaded() && base_k->is_instance_klass() ) {
1717 ciInstanceKlass* ik = base_k->as_instance_klass();
1718 // See if we can become precise: no subklasses and no interface
1719 if (!ik->is_interface() && !ik->has_subklass()) {
1720 //assert(!UseExactTypes, "this code should be useless with exact types");
1721 // Add a dependence; if any subclass added we need to recompile
1722 if (!ik->is_final()) {
1723 phase->C->dependencies()->assert_leaf_type(ik);
1724 }
1725 // Return precise array klass
1726 return TypeKlassPtr::make(ak);
1727 }
1728 }
1729 return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/);
1730 } else { // Found a type-array?
1731 //assert(!UseExactTypes, "this code should be useless with exact types");
1732 assert( ak->is_type_array_klass(), "" );
1733 return TypeKlassPtr::make(ak); // These are always precise
1734 }
1735 }
1736 }
1738 // Check for loading klass from an array klass
1739 const TypeKlassPtr *tkls = tp->isa_klassptr();
1740 if (tkls != NULL && !StressReflectiveCode) {
1741 ciKlass* klass = tkls->klass();
1742 if( !klass->is_loaded() )
1743 return _type; // Bail out if not loaded
1744 if( klass->is_obj_array_klass() &&
1745 (uint)tkls->offset() == objArrayKlass::element_klass_offset_in_bytes() + sizeof(oopDesc)) {
1746 ciKlass* elem = klass->as_obj_array_klass()->element_klass();
1747 // // Always returning precise element type is incorrect,
1748 // // e.g., element type could be object and array may contain strings
1749 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
1751 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
1752 // according to the element type's subclassing.
1753 return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/);
1754 }
1755 if( klass->is_instance_klass() && tkls->klass_is_exact() &&
1756 (uint)tkls->offset() == Klass::super_offset_in_bytes() + sizeof(oopDesc)) {
1757 ciKlass* sup = klass->as_instance_klass()->super();
1758 // The field is Klass::_super. Return its (constant) value.
1759 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
1760 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR;
1761 }
1762 }
1764 // Bailout case
1765 return LoadNode::Value(phase);
1766 }
1768 //------------------------------Identity---------------------------------------
1769 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
1770 // Also feed through the klass in Allocate(...klass...)._klass.
1771 Node* LoadKlassNode::Identity( PhaseTransform *phase ) {
1772 return klass_identity_common(phase);
1773 }
1775 Node* LoadNode::klass_identity_common(PhaseTransform *phase ) {
1776 Node* x = LoadNode::Identity(phase);
1777 if (x != this) return x;
1779 // Take apart the address into an oop and and offset.
1780 // Return 'this' if we cannot.
1781 Node* adr = in(MemNode::Address);
1782 intptr_t offset = 0;
1783 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
1784 if (base == NULL) return this;
1785 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
1786 if (toop == NULL) return this;
1788 // We can fetch the klass directly through an AllocateNode.
1789 // This works even if the klass is not constant (clone or newArray).
1790 if (offset == oopDesc::klass_offset_in_bytes()) {
1791 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
1792 if (allocated_klass != NULL) {
1793 return allocated_klass;
1794 }
1795 }
1797 // Simplify k.java_mirror.as_klass to plain k, where k is a klassOop.
1798 // Simplify ak.component_mirror.array_klass to plain ak, ak an arrayKlass.
1799 // See inline_native_Class_query for occurrences of these patterns.
1800 // Java Example: x.getClass().isAssignableFrom(y)
1801 // Java Example: Array.newInstance(x.getClass().getComponentType(), n)
1802 //
1803 // This improves reflective code, often making the Class
1804 // mirror go completely dead. (Current exception: Class
1805 // mirrors may appear in debug info, but we could clean them out by
1806 // introducing a new debug info operator for klassOop.java_mirror).
1807 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass()
1808 && (offset == java_lang_Class::klass_offset_in_bytes() ||
1809 offset == java_lang_Class::array_klass_offset_in_bytes())) {
1810 // We are loading a special hidden field from a Class mirror,
1811 // the field which points to its Klass or arrayKlass metaobject.
1812 if (base->is_Load()) {
1813 Node* adr2 = base->in(MemNode::Address);
1814 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
1815 if (tkls != NULL && !tkls->empty()
1816 && (tkls->klass()->is_instance_klass() ||
1817 tkls->klass()->is_array_klass())
1818 && adr2->is_AddP()
1819 ) {
1820 int mirror_field = Klass::java_mirror_offset_in_bytes();
1821 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
1822 mirror_field = in_bytes(arrayKlass::component_mirror_offset());
1823 }
1824 if (tkls->offset() == mirror_field + (int)sizeof(oopDesc)) {
1825 return adr2->in(AddPNode::Base);
1826 }
1827 }
1828 }
1829 }
1831 return this;
1832 }
1835 //------------------------------Value------------------------------------------
1836 const Type *LoadNKlassNode::Value( PhaseTransform *phase ) const {
1837 const Type *t = klass_value_common(phase);
1838 if (t == Type::TOP)
1839 return t;
1841 return t->make_narrowoop();
1842 }
1844 //------------------------------Identity---------------------------------------
1845 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
1846 // Also feed through the klass in Allocate(...klass...)._klass.
1847 Node* LoadNKlassNode::Identity( PhaseTransform *phase ) {
1848 Node *x = klass_identity_common(phase);
1850 const Type *t = phase->type( x );
1851 if( t == Type::TOP ) return x;
1852 if( t->isa_narrowoop()) return x;
1854 return phase->transform(new (phase->C, 2) EncodePNode(x, t->make_narrowoop()));
1855 }
1857 //------------------------------Value-----------------------------------------
1858 const Type *LoadRangeNode::Value( PhaseTransform *phase ) const {
1859 // Either input is TOP ==> the result is TOP
1860 const Type *t1 = phase->type( in(MemNode::Memory) );
1861 if( t1 == Type::TOP ) return Type::TOP;
1862 Node *adr = in(MemNode::Address);
1863 const Type *t2 = phase->type( adr );
1864 if( t2 == Type::TOP ) return Type::TOP;
1865 const TypePtr *tp = t2->is_ptr();
1866 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
1867 const TypeAryPtr *tap = tp->isa_aryptr();
1868 if( !tap ) return _type;
1869 return tap->size();
1870 }
1872 //------------------------------Identity---------------------------------------
1873 // Feed through the length in AllocateArray(...length...)._length.
1874 Node* LoadRangeNode::Identity( PhaseTransform *phase ) {
1875 Node* x = LoadINode::Identity(phase);
1876 if (x != this) return x;
1878 // Take apart the address into an oop and and offset.
1879 // Return 'this' if we cannot.
1880 Node* adr = in(MemNode::Address);
1881 intptr_t offset = 0;
1882 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
1883 if (base == NULL) return this;
1884 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
1885 if (tary == NULL) return this;
1887 // We can fetch the length directly through an AllocateArrayNode.
1888 // This works even if the length is not constant (clone or newArray).
1889 if (offset == arrayOopDesc::length_offset_in_bytes()) {
1890 Node* allocated_length = AllocateArrayNode::Ideal_length(base, phase);
1891 if (allocated_length != NULL) {
1892 return allocated_length;
1893 }
1894 }
1896 return this;
1898 }
1899 //=============================================================================
1900 //---------------------------StoreNode::make-----------------------------------
1901 // Polymorphic factory method:
1902 StoreNode* StoreNode::make( PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt ) {
1903 Compile* C = gvn.C;
1905 switch (bt) {
1906 case T_BOOLEAN:
1907 case T_BYTE: return new (C, 4) StoreBNode(ctl, mem, adr, adr_type, val);
1908 case T_INT: return new (C, 4) StoreINode(ctl, mem, adr, adr_type, val);
1909 case T_CHAR:
1910 case T_SHORT: return new (C, 4) StoreCNode(ctl, mem, adr, adr_type, val);
1911 case T_LONG: return new (C, 4) StoreLNode(ctl, mem, adr, adr_type, val);
1912 case T_FLOAT: return new (C, 4) StoreFNode(ctl, mem, adr, adr_type, val);
1913 case T_DOUBLE: return new (C, 4) StoreDNode(ctl, mem, adr, adr_type, val);
1914 case T_ADDRESS:
1915 case T_OBJECT:
1916 #ifdef _LP64
1917 if (adr->bottom_type()->is_ptr_to_narrowoop() ||
1918 (UseCompressedOops && val->bottom_type()->isa_klassptr() &&
1919 adr->bottom_type()->isa_rawptr())) {
1920 val = gvn.transform(new (C, 2) EncodePNode(val, val->bottom_type()->make_narrowoop()));
1921 return new (C, 4) StoreNNode(ctl, mem, adr, adr_type, val);
1922 } else
1923 #endif
1924 {
1925 return new (C, 4) StorePNode(ctl, mem, adr, adr_type, val);
1926 }
1927 }
1928 ShouldNotReachHere();
1929 return (StoreNode*)NULL;
1930 }
1932 StoreLNode* StoreLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val) {
1933 bool require_atomic = true;
1934 return new (C, 4) StoreLNode(ctl, mem, adr, adr_type, val, require_atomic);
1935 }
1938 //--------------------------bottom_type----------------------------------------
1939 const Type *StoreNode::bottom_type() const {
1940 return Type::MEMORY;
1941 }
1943 //------------------------------hash-------------------------------------------
1944 uint StoreNode::hash() const {
1945 // unroll addition of interesting fields
1946 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
1948 // Since they are not commoned, do not hash them:
1949 return NO_HASH;
1950 }
1952 //------------------------------Ideal------------------------------------------
1953 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
1954 // When a store immediately follows a relevant allocation/initialization,
1955 // try to capture it into the initialization, or hoist it above.
1956 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1957 Node* p = MemNode::Ideal_common(phase, can_reshape);
1958 if (p) return (p == NodeSentinel) ? NULL : p;
1960 Node* mem = in(MemNode::Memory);
1961 Node* address = in(MemNode::Address);
1963 // Back-to-back stores to same address? Fold em up.
1964 // Generally unsafe if I have intervening uses...
1965 if (mem->is_Store() && phase->eqv_uncast(mem->in(MemNode::Address), address)) {
1966 // Looking at a dead closed cycle of memory?
1967 assert(mem != mem->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
1969 assert(Opcode() == mem->Opcode() ||
1970 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw,
1971 "no mismatched stores, except on raw memory");
1973 if (mem->outcnt() == 1 && // check for intervening uses
1974 mem->as_Store()->memory_size() <= this->memory_size()) {
1975 // If anybody other than 'this' uses 'mem', we cannot fold 'mem' away.
1976 // For example, 'mem' might be the final state at a conditional return.
1977 // Or, 'mem' might be used by some node which is live at the same time
1978 // 'this' is live, which might be unschedulable. So, require exactly
1979 // ONE user, the 'this' store, until such time as we clone 'mem' for
1980 // each of 'mem's uses (thus making the exactly-1-user-rule hold true).
1981 if (can_reshape) { // (%%% is this an anachronism?)
1982 set_req_X(MemNode::Memory, mem->in(MemNode::Memory),
1983 phase->is_IterGVN());
1984 } else {
1985 // It's OK to do this in the parser, since DU info is always accurate,
1986 // and the parser always refers to nodes via SafePointNode maps.
1987 set_req(MemNode::Memory, mem->in(MemNode::Memory));
1988 }
1989 return this;
1990 }
1991 }
1993 // Capture an unaliased, unconditional, simple store into an initializer.
1994 // Or, if it is independent of the allocation, hoist it above the allocation.
1995 if (ReduceFieldZeroing && /*can_reshape &&*/
1996 mem->is_Proj() && mem->in(0)->is_Initialize()) {
1997 InitializeNode* init = mem->in(0)->as_Initialize();
1998 intptr_t offset = init->can_capture_store(this, phase);
1999 if (offset > 0) {
2000 Node* moved = init->capture_store(this, offset, phase);
2001 // If the InitializeNode captured me, it made a raw copy of me,
2002 // and I need to disappear.
2003 if (moved != NULL) {
2004 // %%% hack to ensure that Ideal returns a new node:
2005 mem = MergeMemNode::make(phase->C, mem);
2006 return mem; // fold me away
2007 }
2008 }
2009 }
2011 return NULL; // No further progress
2012 }
2014 //------------------------------Value-----------------------------------------
2015 const Type *StoreNode::Value( PhaseTransform *phase ) const {
2016 // Either input is TOP ==> the result is TOP
2017 const Type *t1 = phase->type( in(MemNode::Memory) );
2018 if( t1 == Type::TOP ) return Type::TOP;
2019 const Type *t2 = phase->type( in(MemNode::Address) );
2020 if( t2 == Type::TOP ) return Type::TOP;
2021 const Type *t3 = phase->type( in(MemNode::ValueIn) );
2022 if( t3 == Type::TOP ) return Type::TOP;
2023 return Type::MEMORY;
2024 }
2026 //------------------------------Identity---------------------------------------
2027 // Remove redundant stores:
2028 // Store(m, p, Load(m, p)) changes to m.
2029 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
2030 Node *StoreNode::Identity( PhaseTransform *phase ) {
2031 Node* mem = in(MemNode::Memory);
2032 Node* adr = in(MemNode::Address);
2033 Node* val = in(MemNode::ValueIn);
2035 // Load then Store? Then the Store is useless
2036 if (val->is_Load() &&
2037 phase->eqv_uncast( val->in(MemNode::Address), adr ) &&
2038 phase->eqv_uncast( val->in(MemNode::Memory ), mem ) &&
2039 val->as_Load()->store_Opcode() == Opcode()) {
2040 return mem;
2041 }
2043 // Two stores in a row of the same value?
2044 if (mem->is_Store() &&
2045 phase->eqv_uncast( mem->in(MemNode::Address), adr ) &&
2046 phase->eqv_uncast( mem->in(MemNode::ValueIn), val ) &&
2047 mem->Opcode() == Opcode()) {
2048 return mem;
2049 }
2051 // Store of zero anywhere into a freshly-allocated object?
2052 // Then the store is useless.
2053 // (It must already have been captured by the InitializeNode.)
2054 if (ReduceFieldZeroing && phase->type(val)->is_zero_type()) {
2055 // a newly allocated object is already all-zeroes everywhere
2056 if (mem->is_Proj() && mem->in(0)->is_Allocate()) {
2057 return mem;
2058 }
2060 // the store may also apply to zero-bits in an earlier object
2061 Node* prev_mem = find_previous_store(phase);
2062 // Steps (a), (b): Walk past independent stores to find an exact match.
2063 if (prev_mem != NULL) {
2064 Node* prev_val = can_see_stored_value(prev_mem, phase);
2065 if (prev_val != NULL && phase->eqv(prev_val, val)) {
2066 // prev_val and val might differ by a cast; it would be good
2067 // to keep the more informative of the two.
2068 return mem;
2069 }
2070 }
2071 }
2073 return this;
2074 }
2076 //------------------------------match_edge-------------------------------------
2077 // Do we Match on this edge index or not? Match only memory & value
2078 uint StoreNode::match_edge(uint idx) const {
2079 return idx == MemNode::Address || idx == MemNode::ValueIn;
2080 }
2082 //------------------------------cmp--------------------------------------------
2083 // Do not common stores up together. They generally have to be split
2084 // back up anyways, so do not bother.
2085 uint StoreNode::cmp( const Node &n ) const {
2086 return (&n == this); // Always fail except on self
2087 }
2089 //------------------------------Ideal_masked_input-----------------------------
2090 // Check for a useless mask before a partial-word store
2091 // (StoreB ... (AndI valIn conIa) )
2092 // If (conIa & mask == mask) this simplifies to
2093 // (StoreB ... (valIn) )
2094 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
2095 Node *val = in(MemNode::ValueIn);
2096 if( val->Opcode() == Op_AndI ) {
2097 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2098 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
2099 set_req(MemNode::ValueIn, val->in(1));
2100 return this;
2101 }
2102 }
2103 return NULL;
2104 }
2107 //------------------------------Ideal_sign_extended_input----------------------
2108 // Check for useless sign-extension before a partial-word store
2109 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) )
2110 // If (conIL == conIR && conIR <= num_bits) this simplifies to
2111 // (StoreB ... (valIn) )
2112 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) {
2113 Node *val = in(MemNode::ValueIn);
2114 if( val->Opcode() == Op_RShiftI ) {
2115 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2116 if( t && t->is_con() && (t->get_con() <= num_bits) ) {
2117 Node *shl = val->in(1);
2118 if( shl->Opcode() == Op_LShiftI ) {
2119 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int();
2120 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) {
2121 set_req(MemNode::ValueIn, shl->in(1));
2122 return this;
2123 }
2124 }
2125 }
2126 }
2127 return NULL;
2128 }
2130 //------------------------------value_never_loaded-----------------------------------
2131 // Determine whether there are any possible loads of the value stored.
2132 // For simplicity, we actually check if there are any loads from the
2133 // address stored to, not just for loads of the value stored by this node.
2134 //
2135 bool StoreNode::value_never_loaded( PhaseTransform *phase) const {
2136 Node *adr = in(Address);
2137 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
2138 if (adr_oop == NULL)
2139 return false;
2140 if (!adr_oop->is_known_instance_field())
2141 return false; // if not a distinct instance, there may be aliases of the address
2142 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
2143 Node *use = adr->fast_out(i);
2144 int opc = use->Opcode();
2145 if (use->is_Load() || use->is_LoadStore()) {
2146 return false;
2147 }
2148 }
2149 return true;
2150 }
2152 //=============================================================================
2153 //------------------------------Ideal------------------------------------------
2154 // If the store is from an AND mask that leaves the low bits untouched, then
2155 // we can skip the AND operation. If the store is from a sign-extension
2156 // (a left shift, then right shift) we can skip both.
2157 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
2158 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
2159 if( progress != NULL ) return progress;
2161 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
2162 if( progress != NULL ) return progress;
2164 // Finally check the default case
2165 return StoreNode::Ideal(phase, can_reshape);
2166 }
2168 //=============================================================================
2169 //------------------------------Ideal------------------------------------------
2170 // If the store is from an AND mask that leaves the low bits untouched, then
2171 // we can skip the AND operation
2172 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
2173 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
2174 if( progress != NULL ) return progress;
2176 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
2177 if( progress != NULL ) return progress;
2179 // Finally check the default case
2180 return StoreNode::Ideal(phase, can_reshape);
2181 }
2183 //=============================================================================
2184 //------------------------------Identity---------------------------------------
2185 Node *StoreCMNode::Identity( PhaseTransform *phase ) {
2186 // No need to card mark when storing a null ptr
2187 Node* my_store = in(MemNode::OopStore);
2188 if (my_store->is_Store()) {
2189 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) );
2190 if( t1 == TypePtr::NULL_PTR ) {
2191 return in(MemNode::Memory);
2192 }
2193 }
2194 return this;
2195 }
2197 //------------------------------Value-----------------------------------------
2198 const Type *StoreCMNode::Value( PhaseTransform *phase ) const {
2199 // Either input is TOP ==> the result is TOP
2200 const Type *t = phase->type( in(MemNode::Memory) );
2201 if( t == Type::TOP ) return Type::TOP;
2202 t = phase->type( in(MemNode::Address) );
2203 if( t == Type::TOP ) return Type::TOP;
2204 t = phase->type( in(MemNode::ValueIn) );
2205 if( t == Type::TOP ) return Type::TOP;
2206 // If extra input is TOP ==> the result is TOP
2207 t = phase->type( in(MemNode::OopStore) );
2208 if( t == Type::TOP ) return Type::TOP;
2210 return StoreNode::Value( phase );
2211 }
2214 //=============================================================================
2215 //----------------------------------SCMemProjNode------------------------------
2216 const Type * SCMemProjNode::Value( PhaseTransform *phase ) const
2217 {
2218 return bottom_type();
2219 }
2221 //=============================================================================
2222 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : Node(5) {
2223 init_req(MemNode::Control, c );
2224 init_req(MemNode::Memory , mem);
2225 init_req(MemNode::Address, adr);
2226 init_req(MemNode::ValueIn, val);
2227 init_req( ExpectedIn, ex );
2228 init_class_id(Class_LoadStore);
2230 }
2232 //=============================================================================
2233 //-------------------------------adr_type--------------------------------------
2234 // Do we Match on this edge index or not? Do not match memory
2235 const TypePtr* ClearArrayNode::adr_type() const {
2236 Node *adr = in(3);
2237 return MemNode::calculate_adr_type(adr->bottom_type());
2238 }
2240 //------------------------------match_edge-------------------------------------
2241 // Do we Match on this edge index or not? Do not match memory
2242 uint ClearArrayNode::match_edge(uint idx) const {
2243 return idx > 1;
2244 }
2246 //------------------------------Identity---------------------------------------
2247 // Clearing a zero length array does nothing
2248 Node *ClearArrayNode::Identity( PhaseTransform *phase ) {
2249 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
2250 }
2252 //------------------------------Idealize---------------------------------------
2253 // Clearing a short array is faster with stores
2254 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape){
2255 const int unit = BytesPerLong;
2256 const TypeX* t = phase->type(in(2))->isa_intptr_t();
2257 if (!t) return NULL;
2258 if (!t->is_con()) return NULL;
2259 intptr_t raw_count = t->get_con();
2260 intptr_t size = raw_count;
2261 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
2262 // Clearing nothing uses the Identity call.
2263 // Negative clears are possible on dead ClearArrays
2264 // (see jck test stmt114.stmt11402.val).
2265 if (size <= 0 || size % unit != 0) return NULL;
2266 intptr_t count = size / unit;
2267 // Length too long; use fast hardware clear
2268 if (size > Matcher::init_array_short_size) return NULL;
2269 Node *mem = in(1);
2270 if( phase->type(mem)==Type::TOP ) return NULL;
2271 Node *adr = in(3);
2272 const Type* at = phase->type(adr);
2273 if( at==Type::TOP ) return NULL;
2274 const TypePtr* atp = at->isa_ptr();
2275 // adjust atp to be the correct array element address type
2276 if (atp == NULL) atp = TypePtr::BOTTOM;
2277 else atp = atp->add_offset(Type::OffsetBot);
2278 // Get base for derived pointer purposes
2279 if( adr->Opcode() != Op_AddP ) Unimplemented();
2280 Node *base = adr->in(1);
2282 Node *zero = phase->makecon(TypeLong::ZERO);
2283 Node *off = phase->MakeConX(BytesPerLong);
2284 mem = new (phase->C, 4) StoreLNode(in(0),mem,adr,atp,zero);
2285 count--;
2286 while( count-- ) {
2287 mem = phase->transform(mem);
2288 adr = phase->transform(new (phase->C, 4) AddPNode(base,adr,off));
2289 mem = new (phase->C, 4) StoreLNode(in(0),mem,adr,atp,zero);
2290 }
2291 return mem;
2292 }
2294 //----------------------------clear_memory-------------------------------------
2295 // Generate code to initialize object storage to zero.
2296 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2297 intptr_t start_offset,
2298 Node* end_offset,
2299 PhaseGVN* phase) {
2300 Compile* C = phase->C;
2301 intptr_t offset = start_offset;
2303 int unit = BytesPerLong;
2304 if ((offset % unit) != 0) {
2305 Node* adr = new (C, 4) AddPNode(dest, dest, phase->MakeConX(offset));
2306 adr = phase->transform(adr);
2307 const TypePtr* atp = TypeRawPtr::BOTTOM;
2308 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT);
2309 mem = phase->transform(mem);
2310 offset += BytesPerInt;
2311 }
2312 assert((offset % unit) == 0, "");
2314 // Initialize the remaining stuff, if any, with a ClearArray.
2315 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase);
2316 }
2318 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2319 Node* start_offset,
2320 Node* end_offset,
2321 PhaseGVN* phase) {
2322 if (start_offset == end_offset) {
2323 // nothing to do
2324 return mem;
2325 }
2327 Compile* C = phase->C;
2328 int unit = BytesPerLong;
2329 Node* zbase = start_offset;
2330 Node* zend = end_offset;
2332 // Scale to the unit required by the CPU:
2333 if (!Matcher::init_array_count_is_in_bytes) {
2334 Node* shift = phase->intcon(exact_log2(unit));
2335 zbase = phase->transform( new(C,3) URShiftXNode(zbase, shift) );
2336 zend = phase->transform( new(C,3) URShiftXNode(zend, shift) );
2337 }
2339 Node* zsize = phase->transform( new(C,3) SubXNode(zend, zbase) );
2340 Node* zinit = phase->zerocon((unit == BytesPerLong) ? T_LONG : T_INT);
2342 // Bulk clear double-words
2343 Node* adr = phase->transform( new(C,4) AddPNode(dest, dest, start_offset) );
2344 mem = new (C, 4) ClearArrayNode(ctl, mem, zsize, adr);
2345 return phase->transform(mem);
2346 }
2348 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2349 intptr_t start_offset,
2350 intptr_t end_offset,
2351 PhaseGVN* phase) {
2352 if (start_offset == end_offset) {
2353 // nothing to do
2354 return mem;
2355 }
2357 Compile* C = phase->C;
2358 assert((end_offset % BytesPerInt) == 0, "odd end offset");
2359 intptr_t done_offset = end_offset;
2360 if ((done_offset % BytesPerLong) != 0) {
2361 done_offset -= BytesPerInt;
2362 }
2363 if (done_offset > start_offset) {
2364 mem = clear_memory(ctl, mem, dest,
2365 start_offset, phase->MakeConX(done_offset), phase);
2366 }
2367 if (done_offset < end_offset) { // emit the final 32-bit store
2368 Node* adr = new (C, 4) AddPNode(dest, dest, phase->MakeConX(done_offset));
2369 adr = phase->transform(adr);
2370 const TypePtr* atp = TypeRawPtr::BOTTOM;
2371 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT);
2372 mem = phase->transform(mem);
2373 done_offset += BytesPerInt;
2374 }
2375 assert(done_offset == end_offset, "");
2376 return mem;
2377 }
2379 //=============================================================================
2380 // Do we match on this edge? No memory edges
2381 uint StrCompNode::match_edge(uint idx) const {
2382 return idx == 5 || idx == 6;
2383 }
2385 //------------------------------Ideal------------------------------------------
2386 // Return a node which is more "ideal" than the current node. Strip out
2387 // control copies
2388 Node *StrCompNode::Ideal(PhaseGVN *phase, bool can_reshape){
2389 return remove_dead_region(phase, can_reshape) ? this : NULL;
2390 }
2392 //------------------------------Ideal------------------------------------------
2393 // Return a node which is more "ideal" than the current node. Strip out
2394 // control copies
2395 Node *AryEqNode::Ideal(PhaseGVN *phase, bool can_reshape){
2396 return remove_dead_region(phase, can_reshape) ? this : NULL;
2397 }
2400 //=============================================================================
2401 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
2402 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)),
2403 _adr_type(C->get_adr_type(alias_idx))
2404 {
2405 init_class_id(Class_MemBar);
2406 Node* top = C->top();
2407 init_req(TypeFunc::I_O,top);
2408 init_req(TypeFunc::FramePtr,top);
2409 init_req(TypeFunc::ReturnAdr,top);
2410 if (precedent != NULL)
2411 init_req(TypeFunc::Parms, precedent);
2412 }
2414 //------------------------------cmp--------------------------------------------
2415 uint MemBarNode::hash() const { return NO_HASH; }
2416 uint MemBarNode::cmp( const Node &n ) const {
2417 return (&n == this); // Always fail except on self
2418 }
2420 //------------------------------make-------------------------------------------
2421 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
2422 int len = Precedent + (pn == NULL? 0: 1);
2423 switch (opcode) {
2424 case Op_MemBarAcquire: return new(C, len) MemBarAcquireNode(C, atp, pn);
2425 case Op_MemBarRelease: return new(C, len) MemBarReleaseNode(C, atp, pn);
2426 case Op_MemBarVolatile: return new(C, len) MemBarVolatileNode(C, atp, pn);
2427 case Op_MemBarCPUOrder: return new(C, len) MemBarCPUOrderNode(C, atp, pn);
2428 case Op_Initialize: return new(C, len) InitializeNode(C, atp, pn);
2429 default: ShouldNotReachHere(); return NULL;
2430 }
2431 }
2433 //------------------------------Ideal------------------------------------------
2434 // Return a node which is more "ideal" than the current node. Strip out
2435 // control copies
2436 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2437 if (remove_dead_region(phase, can_reshape)) return this;
2438 return NULL;
2439 }
2441 //------------------------------Value------------------------------------------
2442 const Type *MemBarNode::Value( PhaseTransform *phase ) const {
2443 if( !in(0) ) return Type::TOP;
2444 if( phase->type(in(0)) == Type::TOP )
2445 return Type::TOP;
2446 return TypeTuple::MEMBAR;
2447 }
2449 //------------------------------match------------------------------------------
2450 // Construct projections for memory.
2451 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) {
2452 switch (proj->_con) {
2453 case TypeFunc::Control:
2454 case TypeFunc::Memory:
2455 return new (m->C, 1) MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
2456 }
2457 ShouldNotReachHere();
2458 return NULL;
2459 }
2461 //===========================InitializeNode====================================
2462 // SUMMARY:
2463 // This node acts as a memory barrier on raw memory, after some raw stores.
2464 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
2465 // The Initialize can 'capture' suitably constrained stores as raw inits.
2466 // It can coalesce related raw stores into larger units (called 'tiles').
2467 // It can avoid zeroing new storage for memory units which have raw inits.
2468 // At macro-expansion, it is marked 'complete', and does not optimize further.
2469 //
2470 // EXAMPLE:
2471 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
2472 // ctl = incoming control; mem* = incoming memory
2473 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
2474 // First allocate uninitialized memory and fill in the header:
2475 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
2476 // ctl := alloc.Control; mem* := alloc.Memory*
2477 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
2478 // Then initialize to zero the non-header parts of the raw memory block:
2479 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
2480 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
2481 // After the initialize node executes, the object is ready for service:
2482 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
2483 // Suppose its body is immediately initialized as {1,2}:
2484 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
2485 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
2486 // mem.SLICE(#short[*]) := store2
2487 //
2488 // DETAILS:
2489 // An InitializeNode collects and isolates object initialization after
2490 // an AllocateNode and before the next possible safepoint. As a
2491 // memory barrier (MemBarNode), it keeps critical stores from drifting
2492 // down past any safepoint or any publication of the allocation.
2493 // Before this barrier, a newly-allocated object may have uninitialized bits.
2494 // After this barrier, it may be treated as a real oop, and GC is allowed.
2495 //
2496 // The semantics of the InitializeNode include an implicit zeroing of
2497 // the new object from object header to the end of the object.
2498 // (The object header and end are determined by the AllocateNode.)
2499 //
2500 // Certain stores may be added as direct inputs to the InitializeNode.
2501 // These stores must update raw memory, and they must be to addresses
2502 // derived from the raw address produced by AllocateNode, and with
2503 // a constant offset. They must be ordered by increasing offset.
2504 // The first one is at in(RawStores), the last at in(req()-1).
2505 // Unlike most memory operations, they are not linked in a chain,
2506 // but are displayed in parallel as users of the rawmem output of
2507 // the allocation.
2508 //
2509 // (See comments in InitializeNode::capture_store, which continue
2510 // the example given above.)
2511 //
2512 // When the associated Allocate is macro-expanded, the InitializeNode
2513 // may be rewritten to optimize collected stores. A ClearArrayNode
2514 // may also be created at that point to represent any required zeroing.
2515 // The InitializeNode is then marked 'complete', prohibiting further
2516 // capturing of nearby memory operations.
2517 //
2518 // During macro-expansion, all captured initializations which store
2519 // constant values of 32 bits or smaller are coalesced (if advantagous)
2520 // into larger 'tiles' 32 or 64 bits. This allows an object to be
2521 // initialized in fewer memory operations. Memory words which are
2522 // covered by neither tiles nor non-constant stores are pre-zeroed
2523 // by explicit stores of zero. (The code shape happens to do all
2524 // zeroing first, then all other stores, with both sequences occurring
2525 // in order of ascending offsets.)
2526 //
2527 // Alternatively, code may be inserted between an AllocateNode and its
2528 // InitializeNode, to perform arbitrary initialization of the new object.
2529 // E.g., the object copying intrinsics insert complex data transfers here.
2530 // The initialization must then be marked as 'complete' disable the
2531 // built-in zeroing semantics and the collection of initializing stores.
2532 //
2533 // While an InitializeNode is incomplete, reads from the memory state
2534 // produced by it are optimizable if they match the control edge and
2535 // new oop address associated with the allocation/initialization.
2536 // They return a stored value (if the offset matches) or else zero.
2537 // A write to the memory state, if it matches control and address,
2538 // and if it is to a constant offset, may be 'captured' by the
2539 // InitializeNode. It is cloned as a raw memory operation and rewired
2540 // inside the initialization, to the raw oop produced by the allocation.
2541 // Operations on addresses which are provably distinct (e.g., to
2542 // other AllocateNodes) are allowed to bypass the initialization.
2543 //
2544 // The effect of all this is to consolidate object initialization
2545 // (both arrays and non-arrays, both piecewise and bulk) into a
2546 // single location, where it can be optimized as a unit.
2547 //
2548 // Only stores with an offset less than TrackedInitializationLimit words
2549 // will be considered for capture by an InitializeNode. This puts a
2550 // reasonable limit on the complexity of optimized initializations.
2552 //---------------------------InitializeNode------------------------------------
2553 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
2554 : _is_complete(false),
2555 MemBarNode(C, adr_type, rawoop)
2556 {
2557 init_class_id(Class_Initialize);
2559 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
2560 assert(in(RawAddress) == rawoop, "proper init");
2561 // Note: allocation() can be NULL, for secondary initialization barriers
2562 }
2564 // Since this node is not matched, it will be processed by the
2565 // register allocator. Declare that there are no constraints
2566 // on the allocation of the RawAddress edge.
2567 const RegMask &InitializeNode::in_RegMask(uint idx) const {
2568 // This edge should be set to top, by the set_complete. But be conservative.
2569 if (idx == InitializeNode::RawAddress)
2570 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
2571 return RegMask::Empty;
2572 }
2574 Node* InitializeNode::memory(uint alias_idx) {
2575 Node* mem = in(Memory);
2576 if (mem->is_MergeMem()) {
2577 return mem->as_MergeMem()->memory_at(alias_idx);
2578 } else {
2579 // incoming raw memory is not split
2580 return mem;
2581 }
2582 }
2584 bool InitializeNode::is_non_zero() {
2585 if (is_complete()) return false;
2586 remove_extra_zeroes();
2587 return (req() > RawStores);
2588 }
2590 void InitializeNode::set_complete(PhaseGVN* phase) {
2591 assert(!is_complete(), "caller responsibility");
2592 _is_complete = true;
2594 // After this node is complete, it contains a bunch of
2595 // raw-memory initializations. There is no need for
2596 // it to have anything to do with non-raw memory effects.
2597 // Therefore, tell all non-raw users to re-optimize themselves,
2598 // after skipping the memory effects of this initialization.
2599 PhaseIterGVN* igvn = phase->is_IterGVN();
2600 if (igvn) igvn->add_users_to_worklist(this);
2601 }
2603 // convenience function
2604 // return false if the init contains any stores already
2605 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
2606 InitializeNode* init = initialization();
2607 if (init == NULL || init->is_complete()) return false;
2608 init->remove_extra_zeroes();
2609 // for now, if this allocation has already collected any inits, bail:
2610 if (init->is_non_zero()) return false;
2611 init->set_complete(phase);
2612 return true;
2613 }
2615 void InitializeNode::remove_extra_zeroes() {
2616 if (req() == RawStores) return;
2617 Node* zmem = zero_memory();
2618 uint fill = RawStores;
2619 for (uint i = fill; i < req(); i++) {
2620 Node* n = in(i);
2621 if (n->is_top() || n == zmem) continue; // skip
2622 if (fill < i) set_req(fill, n); // compact
2623 ++fill;
2624 }
2625 // delete any empty spaces created:
2626 while (fill < req()) {
2627 del_req(fill);
2628 }
2629 }
2631 // Helper for remembering which stores go with which offsets.
2632 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) {
2633 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
2634 intptr_t offset = -1;
2635 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
2636 phase, offset);
2637 if (base == NULL) return -1; // something is dead,
2638 if (offset < 0) return -1; // dead, dead
2639 return offset;
2640 }
2642 // Helper for proving that an initialization expression is
2643 // "simple enough" to be folded into an object initialization.
2644 // Attempts to prove that a store's initial value 'n' can be captured
2645 // within the initialization without creating a vicious cycle, such as:
2646 // { Foo p = new Foo(); p.next = p; }
2647 // True for constants and parameters and small combinations thereof.
2648 bool InitializeNode::detect_init_independence(Node* n,
2649 bool st_is_pinned,
2650 int& count) {
2651 if (n == NULL) return true; // (can this really happen?)
2652 if (n->is_Proj()) n = n->in(0);
2653 if (n == this) return false; // found a cycle
2654 if (n->is_Con()) return true;
2655 if (n->is_Start()) return true; // params, etc., are OK
2656 if (n->is_Root()) return true; // even better
2658 Node* ctl = n->in(0);
2659 if (ctl != NULL && !ctl->is_top()) {
2660 if (ctl->is_Proj()) ctl = ctl->in(0);
2661 if (ctl == this) return false;
2663 // If we already know that the enclosing memory op is pinned right after
2664 // the init, then any control flow that the store has picked up
2665 // must have preceded the init, or else be equal to the init.
2666 // Even after loop optimizations (which might change control edges)
2667 // a store is never pinned *before* the availability of its inputs.
2668 if (!MemNode::all_controls_dominate(n, this))
2669 return false; // failed to prove a good control
2671 }
2673 // Check data edges for possible dependencies on 'this'.
2674 if ((count += 1) > 20) return false; // complexity limit
2675 for (uint i = 1; i < n->req(); i++) {
2676 Node* m = n->in(i);
2677 if (m == NULL || m == n || m->is_top()) continue;
2678 uint first_i = n->find_edge(m);
2679 if (i != first_i) continue; // process duplicate edge just once
2680 if (!detect_init_independence(m, st_is_pinned, count)) {
2681 return false;
2682 }
2683 }
2685 return true;
2686 }
2688 // Here are all the checks a Store must pass before it can be moved into
2689 // an initialization. Returns zero if a check fails.
2690 // On success, returns the (constant) offset to which the store applies,
2691 // within the initialized memory.
2692 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase) {
2693 const int FAIL = 0;
2694 if (st->req() != MemNode::ValueIn + 1)
2695 return FAIL; // an inscrutable StoreNode (card mark?)
2696 Node* ctl = st->in(MemNode::Control);
2697 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this))
2698 return FAIL; // must be unconditional after the initialization
2699 Node* mem = st->in(MemNode::Memory);
2700 if (!(mem->is_Proj() && mem->in(0) == this))
2701 return FAIL; // must not be preceded by other stores
2702 Node* adr = st->in(MemNode::Address);
2703 intptr_t offset;
2704 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
2705 if (alloc == NULL)
2706 return FAIL; // inscrutable address
2707 if (alloc != allocation())
2708 return FAIL; // wrong allocation! (store needs to float up)
2709 Node* val = st->in(MemNode::ValueIn);
2710 int complexity_count = 0;
2711 if (!detect_init_independence(val, true, complexity_count))
2712 return FAIL; // stored value must be 'simple enough'
2714 return offset; // success
2715 }
2717 // Find the captured store in(i) which corresponds to the range
2718 // [start..start+size) in the initialized object.
2719 // If there is one, return its index i. If there isn't, return the
2720 // negative of the index where it should be inserted.
2721 // Return 0 if the queried range overlaps an initialization boundary
2722 // or if dead code is encountered.
2723 // If size_in_bytes is zero, do not bother with overlap checks.
2724 int InitializeNode::captured_store_insertion_point(intptr_t start,
2725 int size_in_bytes,
2726 PhaseTransform* phase) {
2727 const int FAIL = 0, MAX_STORE = BytesPerLong;
2729 if (is_complete())
2730 return FAIL; // arraycopy got here first; punt
2732 assert(allocation() != NULL, "must be present");
2734 // no negatives, no header fields:
2735 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
2737 // after a certain size, we bail out on tracking all the stores:
2738 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
2739 if (start >= ti_limit) return FAIL;
2741 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
2742 if (i >= limit) return -(int)i; // not found; here is where to put it
2744 Node* st = in(i);
2745 intptr_t st_off = get_store_offset(st, phase);
2746 if (st_off < 0) {
2747 if (st != zero_memory()) {
2748 return FAIL; // bail out if there is dead garbage
2749 }
2750 } else if (st_off > start) {
2751 // ...we are done, since stores are ordered
2752 if (st_off < start + size_in_bytes) {
2753 return FAIL; // the next store overlaps
2754 }
2755 return -(int)i; // not found; here is where to put it
2756 } else if (st_off < start) {
2757 if (size_in_bytes != 0 &&
2758 start < st_off + MAX_STORE &&
2759 start < st_off + st->as_Store()->memory_size()) {
2760 return FAIL; // the previous store overlaps
2761 }
2762 } else {
2763 if (size_in_bytes != 0 &&
2764 st->as_Store()->memory_size() != size_in_bytes) {
2765 return FAIL; // mismatched store size
2766 }
2767 return i;
2768 }
2770 ++i;
2771 }
2772 }
2774 // Look for a captured store which initializes at the offset 'start'
2775 // with the given size. If there is no such store, and no other
2776 // initialization interferes, then return zero_memory (the memory
2777 // projection of the AllocateNode).
2778 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
2779 PhaseTransform* phase) {
2780 assert(stores_are_sane(phase), "");
2781 int i = captured_store_insertion_point(start, size_in_bytes, phase);
2782 if (i == 0) {
2783 return NULL; // something is dead
2784 } else if (i < 0) {
2785 return zero_memory(); // just primordial zero bits here
2786 } else {
2787 Node* st = in(i); // here is the store at this position
2788 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
2789 return st;
2790 }
2791 }
2793 // Create, as a raw pointer, an address within my new object at 'offset'.
2794 Node* InitializeNode::make_raw_address(intptr_t offset,
2795 PhaseTransform* phase) {
2796 Node* addr = in(RawAddress);
2797 if (offset != 0) {
2798 Compile* C = phase->C;
2799 addr = phase->transform( new (C, 4) AddPNode(C->top(), addr,
2800 phase->MakeConX(offset)) );
2801 }
2802 return addr;
2803 }
2805 // Clone the given store, converting it into a raw store
2806 // initializing a field or element of my new object.
2807 // Caller is responsible for retiring the original store,
2808 // with subsume_node or the like.
2809 //
2810 // From the example above InitializeNode::InitializeNode,
2811 // here are the old stores to be captured:
2812 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
2813 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
2814 //
2815 // Here is the changed code; note the extra edges on init:
2816 // alloc = (Allocate ...)
2817 // rawoop = alloc.RawAddress
2818 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
2819 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
2820 // init = (Initialize alloc.Control alloc.Memory rawoop
2821 // rawstore1 rawstore2)
2822 //
2823 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
2824 PhaseTransform* phase) {
2825 assert(stores_are_sane(phase), "");
2827 if (start < 0) return NULL;
2828 assert(can_capture_store(st, phase) == start, "sanity");
2830 Compile* C = phase->C;
2831 int size_in_bytes = st->memory_size();
2832 int i = captured_store_insertion_point(start, size_in_bytes, phase);
2833 if (i == 0) return NULL; // bail out
2834 Node* prev_mem = NULL; // raw memory for the captured store
2835 if (i > 0) {
2836 prev_mem = in(i); // there is a pre-existing store under this one
2837 set_req(i, C->top()); // temporarily disconnect it
2838 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
2839 } else {
2840 i = -i; // no pre-existing store
2841 prev_mem = zero_memory(); // a slice of the newly allocated object
2842 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
2843 set_req(--i, C->top()); // reuse this edge; it has been folded away
2844 else
2845 ins_req(i, C->top()); // build a new edge
2846 }
2847 Node* new_st = st->clone();
2848 new_st->set_req(MemNode::Control, in(Control));
2849 new_st->set_req(MemNode::Memory, prev_mem);
2850 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
2851 new_st = phase->transform(new_st);
2853 // At this point, new_st might have swallowed a pre-existing store
2854 // at the same offset, or perhaps new_st might have disappeared,
2855 // if it redundantly stored the same value (or zero to fresh memory).
2857 // In any case, wire it in:
2858 set_req(i, new_st);
2860 // The caller may now kill the old guy.
2861 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
2862 assert(check_st == new_st || check_st == NULL, "must be findable");
2863 assert(!is_complete(), "");
2864 return new_st;
2865 }
2867 static bool store_constant(jlong* tiles, int num_tiles,
2868 intptr_t st_off, int st_size,
2869 jlong con) {
2870 if ((st_off & (st_size-1)) != 0)
2871 return false; // strange store offset (assume size==2**N)
2872 address addr = (address)tiles + st_off;
2873 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
2874 switch (st_size) {
2875 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
2876 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
2877 case sizeof(jint): *(jint*) addr = (jint) con; break;
2878 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
2879 default: return false; // strange store size (detect size!=2**N here)
2880 }
2881 return true; // return success to caller
2882 }
2884 // Coalesce subword constants into int constants and possibly
2885 // into long constants. The goal, if the CPU permits,
2886 // is to initialize the object with a small number of 64-bit tiles.
2887 // Also, convert floating-point constants to bit patterns.
2888 // Non-constants are not relevant to this pass.
2889 //
2890 // In terms of the running example on InitializeNode::InitializeNode
2891 // and InitializeNode::capture_store, here is the transformation
2892 // of rawstore1 and rawstore2 into rawstore12:
2893 // alloc = (Allocate ...)
2894 // rawoop = alloc.RawAddress
2895 // tile12 = 0x00010002
2896 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
2897 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
2898 //
2899 void
2900 InitializeNode::coalesce_subword_stores(intptr_t header_size,
2901 Node* size_in_bytes,
2902 PhaseGVN* phase) {
2903 Compile* C = phase->C;
2905 assert(stores_are_sane(phase), "");
2906 // Note: After this pass, they are not completely sane,
2907 // since there may be some overlaps.
2909 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
2911 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
2912 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
2913 size_limit = MIN2(size_limit, ti_limit);
2914 size_limit = align_size_up(size_limit, BytesPerLong);
2915 int num_tiles = size_limit / BytesPerLong;
2917 // allocate space for the tile map:
2918 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
2919 jlong tiles_buf[small_len];
2920 Node* nodes_buf[small_len];
2921 jlong inits_buf[small_len];
2922 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
2923 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
2924 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
2925 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
2926 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
2927 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
2928 // tiles: exact bitwise model of all primitive constants
2929 // nodes: last constant-storing node subsumed into the tiles model
2930 // inits: which bytes (in each tile) are touched by any initializations
2932 //// Pass A: Fill in the tile model with any relevant stores.
2934 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
2935 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
2936 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
2937 Node* zmem = zero_memory(); // initially zero memory state
2938 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
2939 Node* st = in(i);
2940 intptr_t st_off = get_store_offset(st, phase);
2942 // Figure out the store's offset and constant value:
2943 if (st_off < header_size) continue; //skip (ignore header)
2944 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
2945 int st_size = st->as_Store()->memory_size();
2946 if (st_off + st_size > size_limit) break;
2948 // Record which bytes are touched, whether by constant or not.
2949 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
2950 continue; // skip (strange store size)
2952 const Type* val = phase->type(st->in(MemNode::ValueIn));
2953 if (!val->singleton()) continue; //skip (non-con store)
2954 BasicType type = val->basic_type();
2956 jlong con = 0;
2957 switch (type) {
2958 case T_INT: con = val->is_int()->get_con(); break;
2959 case T_LONG: con = val->is_long()->get_con(); break;
2960 case T_FLOAT: con = jint_cast(val->getf()); break;
2961 case T_DOUBLE: con = jlong_cast(val->getd()); break;
2962 default: continue; //skip (odd store type)
2963 }
2965 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
2966 st->Opcode() == Op_StoreL) {
2967 continue; // This StoreL is already optimal.
2968 }
2970 // Store down the constant.
2971 store_constant(tiles, num_tiles, st_off, st_size, con);
2973 intptr_t j = st_off >> LogBytesPerLong;
2975 if (type == T_INT && st_size == BytesPerInt
2976 && (st_off & BytesPerInt) == BytesPerInt) {
2977 jlong lcon = tiles[j];
2978 if (!Matcher::isSimpleConstant64(lcon) &&
2979 st->Opcode() == Op_StoreI) {
2980 // This StoreI is already optimal by itself.
2981 jint* intcon = (jint*) &tiles[j];
2982 intcon[1] = 0; // undo the store_constant()
2984 // If the previous store is also optimal by itself, back up and
2985 // undo the action of the previous loop iteration... if we can.
2986 // But if we can't, just let the previous half take care of itself.
2987 st = nodes[j];
2988 st_off -= BytesPerInt;
2989 con = intcon[0];
2990 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) {
2991 assert(st_off >= header_size, "still ignoring header");
2992 assert(get_store_offset(st, phase) == st_off, "must be");
2993 assert(in(i-1) == zmem, "must be");
2994 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
2995 assert(con == tcon->is_int()->get_con(), "must be");
2996 // Undo the effects of the previous loop trip, which swallowed st:
2997 intcon[0] = 0; // undo store_constant()
2998 set_req(i-1, st); // undo set_req(i, zmem)
2999 nodes[j] = NULL; // undo nodes[j] = st
3000 --old_subword; // undo ++old_subword
3001 }
3002 continue; // This StoreI is already optimal.
3003 }
3004 }
3006 // This store is not needed.
3007 set_req(i, zmem);
3008 nodes[j] = st; // record for the moment
3009 if (st_size < BytesPerLong) // something has changed
3010 ++old_subword; // includes int/float, but who's counting...
3011 else ++old_long;
3012 }
3014 if ((old_subword + old_long) == 0)
3015 return; // nothing more to do
3017 //// Pass B: Convert any non-zero tiles into optimal constant stores.
3018 // Be sure to insert them before overlapping non-constant stores.
3019 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
3020 for (int j = 0; j < num_tiles; j++) {
3021 jlong con = tiles[j];
3022 jlong init = inits[j];
3023 if (con == 0) continue;
3024 jint con0, con1; // split the constant, address-wise
3025 jint init0, init1; // split the init map, address-wise
3026 { union { jlong con; jint intcon[2]; } u;
3027 u.con = con;
3028 con0 = u.intcon[0];
3029 con1 = u.intcon[1];
3030 u.con = init;
3031 init0 = u.intcon[0];
3032 init1 = u.intcon[1];
3033 }
3035 Node* old = nodes[j];
3036 assert(old != NULL, "need the prior store");
3037 intptr_t offset = (j * BytesPerLong);
3039 bool split = !Matcher::isSimpleConstant64(con);
3041 if (offset < header_size) {
3042 assert(offset + BytesPerInt >= header_size, "second int counts");
3043 assert(*(jint*)&tiles[j] == 0, "junk in header");
3044 split = true; // only the second word counts
3045 // Example: int a[] = { 42 ... }
3046 } else if (con0 == 0 && init0 == -1) {
3047 split = true; // first word is covered by full inits
3048 // Example: int a[] = { ... foo(), 42 ... }
3049 } else if (con1 == 0 && init1 == -1) {
3050 split = true; // second word is covered by full inits
3051 // Example: int a[] = { ... 42, foo() ... }
3052 }
3054 // Here's a case where init0 is neither 0 nor -1:
3055 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
3056 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
3057 // In this case the tile is not split; it is (jlong)42.
3058 // The big tile is stored down, and then the foo() value is inserted.
3059 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
3061 Node* ctl = old->in(MemNode::Control);
3062 Node* adr = make_raw_address(offset, phase);
3063 const TypePtr* atp = TypeRawPtr::BOTTOM;
3065 // One or two coalesced stores to plop down.
3066 Node* st[2];
3067 intptr_t off[2];
3068 int nst = 0;
3069 if (!split) {
3070 ++new_long;
3071 off[nst] = offset;
3072 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3073 phase->longcon(con), T_LONG);
3074 } else {
3075 // Omit either if it is a zero.
3076 if (con0 != 0) {
3077 ++new_int;
3078 off[nst] = offset;
3079 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3080 phase->intcon(con0), T_INT);
3081 }
3082 if (con1 != 0) {
3083 ++new_int;
3084 offset += BytesPerInt;
3085 adr = make_raw_address(offset, phase);
3086 off[nst] = offset;
3087 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3088 phase->intcon(con1), T_INT);
3089 }
3090 }
3092 // Insert second store first, then the first before the second.
3093 // Insert each one just before any overlapping non-constant stores.
3094 while (nst > 0) {
3095 Node* st1 = st[--nst];
3096 C->copy_node_notes_to(st1, old);
3097 st1 = phase->transform(st1);
3098 offset = off[nst];
3099 assert(offset >= header_size, "do not smash header");
3100 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
3101 guarantee(ins_idx != 0, "must re-insert constant store");
3102 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
3103 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
3104 set_req(--ins_idx, st1);
3105 else
3106 ins_req(ins_idx, st1);
3107 }
3108 }
3110 if (PrintCompilation && WizardMode)
3111 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
3112 old_subword, old_long, new_int, new_long);
3113 if (C->log() != NULL)
3114 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
3115 old_subword, old_long, new_int, new_long);
3117 // Clean up any remaining occurrences of zmem:
3118 remove_extra_zeroes();
3119 }
3121 // Explore forward from in(start) to find the first fully initialized
3122 // word, and return its offset. Skip groups of subword stores which
3123 // together initialize full words. If in(start) is itself part of a
3124 // fully initialized word, return the offset of in(start). If there
3125 // are no following full-word stores, or if something is fishy, return
3126 // a negative value.
3127 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
3128 int int_map = 0;
3129 intptr_t int_map_off = 0;
3130 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
3132 for (uint i = start, limit = req(); i < limit; i++) {
3133 Node* st = in(i);
3135 intptr_t st_off = get_store_offset(st, phase);
3136 if (st_off < 0) break; // return conservative answer
3138 int st_size = st->as_Store()->memory_size();
3139 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
3140 return st_off; // we found a complete word init
3141 }
3143 // update the map:
3145 intptr_t this_int_off = align_size_down(st_off, BytesPerInt);
3146 if (this_int_off != int_map_off) {
3147 // reset the map:
3148 int_map = 0;
3149 int_map_off = this_int_off;
3150 }
3152 int subword_off = st_off - this_int_off;
3153 int_map |= right_n_bits(st_size) << subword_off;
3154 if ((int_map & FULL_MAP) == FULL_MAP) {
3155 return this_int_off; // we found a complete word init
3156 }
3158 // Did this store hit or cross the word boundary?
3159 intptr_t next_int_off = align_size_down(st_off + st_size, BytesPerInt);
3160 if (next_int_off == this_int_off + BytesPerInt) {
3161 // We passed the current int, without fully initializing it.
3162 int_map_off = next_int_off;
3163 int_map >>= BytesPerInt;
3164 } else if (next_int_off > this_int_off + BytesPerInt) {
3165 // We passed the current and next int.
3166 return this_int_off + BytesPerInt;
3167 }
3168 }
3170 return -1;
3171 }
3174 // Called when the associated AllocateNode is expanded into CFG.
3175 // At this point, we may perform additional optimizations.
3176 // Linearize the stores by ascending offset, to make memory
3177 // activity as coherent as possible.
3178 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
3179 intptr_t header_size,
3180 Node* size_in_bytes,
3181 PhaseGVN* phase) {
3182 assert(!is_complete(), "not already complete");
3183 assert(stores_are_sane(phase), "");
3184 assert(allocation() != NULL, "must be present");
3186 remove_extra_zeroes();
3188 if (ReduceFieldZeroing || ReduceBulkZeroing)
3189 // reduce instruction count for common initialization patterns
3190 coalesce_subword_stores(header_size, size_in_bytes, phase);
3192 Node* zmem = zero_memory(); // initially zero memory state
3193 Node* inits = zmem; // accumulating a linearized chain of inits
3194 #ifdef ASSERT
3195 intptr_t first_offset = allocation()->minimum_header_size();
3196 intptr_t last_init_off = first_offset; // previous init offset
3197 intptr_t last_init_end = first_offset; // previous init offset+size
3198 intptr_t last_tile_end = first_offset; // previous tile offset+size
3199 #endif
3200 intptr_t zeroes_done = header_size;
3202 bool do_zeroing = true; // we might give up if inits are very sparse
3203 int big_init_gaps = 0; // how many large gaps have we seen?
3205 if (ZeroTLAB) do_zeroing = false;
3206 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
3208 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3209 Node* st = in(i);
3210 intptr_t st_off = get_store_offset(st, phase);
3211 if (st_off < 0)
3212 break; // unknown junk in the inits
3213 if (st->in(MemNode::Memory) != zmem)
3214 break; // complicated store chains somehow in list
3216 int st_size = st->as_Store()->memory_size();
3217 intptr_t next_init_off = st_off + st_size;
3219 if (do_zeroing && zeroes_done < next_init_off) {
3220 // See if this store needs a zero before it or under it.
3221 intptr_t zeroes_needed = st_off;
3223 if (st_size < BytesPerInt) {
3224 // Look for subword stores which only partially initialize words.
3225 // If we find some, we must lay down some word-level zeroes first,
3226 // underneath the subword stores.
3227 //
3228 // Examples:
3229 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
3230 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
3231 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
3232 //
3233 // Note: coalesce_subword_stores may have already done this,
3234 // if it was prompted by constant non-zero subword initializers.
3235 // But this case can still arise with non-constant stores.
3237 intptr_t next_full_store = find_next_fullword_store(i, phase);
3239 // In the examples above:
3240 // in(i) p q r s x y z
3241 // st_off 12 13 14 15 12 13 14
3242 // st_size 1 1 1 1 1 1 1
3243 // next_full_s. 12 16 16 16 16 16 16
3244 // z's_done 12 16 16 16 12 16 12
3245 // z's_needed 12 16 16 16 16 16 16
3246 // zsize 0 0 0 0 4 0 4
3247 if (next_full_store < 0) {
3248 // Conservative tack: Zero to end of current word.
3249 zeroes_needed = align_size_up(zeroes_needed, BytesPerInt);
3250 } else {
3251 // Zero to beginning of next fully initialized word.
3252 // Or, don't zero at all, if we are already in that word.
3253 assert(next_full_store >= zeroes_needed, "must go forward");
3254 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
3255 zeroes_needed = next_full_store;
3256 }
3257 }
3259 if (zeroes_needed > zeroes_done) {
3260 intptr_t zsize = zeroes_needed - zeroes_done;
3261 // Do some incremental zeroing on rawmem, in parallel with inits.
3262 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3263 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3264 zeroes_done, zeroes_needed,
3265 phase);
3266 zeroes_done = zeroes_needed;
3267 if (zsize > Matcher::init_array_short_size && ++big_init_gaps > 2)
3268 do_zeroing = false; // leave the hole, next time
3269 }
3270 }
3272 // Collect the store and move on:
3273 st->set_req(MemNode::Memory, inits);
3274 inits = st; // put it on the linearized chain
3275 set_req(i, zmem); // unhook from previous position
3277 if (zeroes_done == st_off)
3278 zeroes_done = next_init_off;
3280 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
3282 #ifdef ASSERT
3283 // Various order invariants. Weaker than stores_are_sane because
3284 // a large constant tile can be filled in by smaller non-constant stores.
3285 assert(st_off >= last_init_off, "inits do not reverse");
3286 last_init_off = st_off;
3287 const Type* val = NULL;
3288 if (st_size >= BytesPerInt &&
3289 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
3290 (int)val->basic_type() < (int)T_OBJECT) {
3291 assert(st_off >= last_tile_end, "tiles do not overlap");
3292 assert(st_off >= last_init_end, "tiles do not overwrite inits");
3293 last_tile_end = MAX2(last_tile_end, next_init_off);
3294 } else {
3295 intptr_t st_tile_end = align_size_up(next_init_off, BytesPerLong);
3296 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
3297 assert(st_off >= last_init_end, "inits do not overlap");
3298 last_init_end = next_init_off; // it's a non-tile
3299 }
3300 #endif //ASSERT
3301 }
3303 remove_extra_zeroes(); // clear out all the zmems left over
3304 add_req(inits);
3306 if (!ZeroTLAB) {
3307 // If anything remains to be zeroed, zero it all now.
3308 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3309 // if it is the last unused 4 bytes of an instance, forget about it
3310 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
3311 if (zeroes_done + BytesPerLong >= size_limit) {
3312 assert(allocation() != NULL, "");
3313 Node* klass_node = allocation()->in(AllocateNode::KlassNode);
3314 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass();
3315 if (zeroes_done == k->layout_helper())
3316 zeroes_done = size_limit;
3317 }
3318 if (zeroes_done < size_limit) {
3319 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3320 zeroes_done, size_in_bytes, phase);
3321 }
3322 }
3324 set_complete(phase);
3325 return rawmem;
3326 }
3329 #ifdef ASSERT
3330 bool InitializeNode::stores_are_sane(PhaseTransform* phase) {
3331 if (is_complete())
3332 return true; // stores could be anything at this point
3333 assert(allocation() != NULL, "must be present");
3334 intptr_t last_off = allocation()->minimum_header_size();
3335 for (uint i = InitializeNode::RawStores; i < req(); i++) {
3336 Node* st = in(i);
3337 intptr_t st_off = get_store_offset(st, phase);
3338 if (st_off < 0) continue; // ignore dead garbage
3339 if (last_off > st_off) {
3340 tty->print_cr("*** bad store offset at %d: %d > %d", i, last_off, st_off);
3341 this->dump(2);
3342 assert(false, "ascending store offsets");
3343 return false;
3344 }
3345 last_off = st_off + st->as_Store()->memory_size();
3346 }
3347 return true;
3348 }
3349 #endif //ASSERT
3354 //============================MergeMemNode=====================================
3355 //
3356 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
3357 // contributing store or call operations. Each contributor provides the memory
3358 // state for a particular "alias type" (see Compile::alias_type). For example,
3359 // if a MergeMem has an input X for alias category #6, then any memory reference
3360 // to alias category #6 may use X as its memory state input, as an exact equivalent
3361 // to using the MergeMem as a whole.
3362 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
3363 //
3364 // (Here, the <N> notation gives the index of the relevant adr_type.)
3365 //
3366 // In one special case (and more cases in the future), alias categories overlap.
3367 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
3368 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
3369 // it is exactly equivalent to that state W:
3370 // MergeMem(<Bot>: W) <==> W
3371 //
3372 // Usually, the merge has more than one input. In that case, where inputs
3373 // overlap (i.e., one is Bot), the narrower alias type determines the memory
3374 // state for that type, and the wider alias type (Bot) fills in everywhere else:
3375 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
3376 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
3377 //
3378 // A merge can take a "wide" memory state as one of its narrow inputs.
3379 // This simply means that the merge observes out only the relevant parts of
3380 // the wide input. That is, wide memory states arriving at narrow merge inputs
3381 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
3382 //
3383 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
3384 // and that memory slices "leak through":
3385 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
3386 //
3387 // But, in such a cascade, repeated memory slices can "block the leak":
3388 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
3389 //
3390 // In the last example, Y is not part of the combined memory state of the
3391 // outermost MergeMem. The system must, of course, prevent unschedulable
3392 // memory states from arising, so you can be sure that the state Y is somehow
3393 // a precursor to state Y'.
3394 //
3395 //
3396 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
3397 // of each MergeMemNode array are exactly the numerical alias indexes, including
3398 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
3399 // Compile::alias_type (and kin) produce and manage these indexes.
3400 //
3401 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
3402 // (Note that this provides quick access to the top node inside MergeMem methods,
3403 // without the need to reach out via TLS to Compile::current.)
3404 //
3405 // As a consequence of what was just described, a MergeMem that represents a full
3406 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
3407 // containing all alias categories.
3408 //
3409 // MergeMem nodes never (?) have control inputs, so in(0) is NULL.
3410 //
3411 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
3412 // a memory state for the alias type <N>, or else the top node, meaning that
3413 // there is no particular input for that alias type. Note that the length of
3414 // a MergeMem is variable, and may be extended at any time to accommodate new
3415 // memory states at larger alias indexes. When merges grow, they are of course
3416 // filled with "top" in the unused in() positions.
3417 //
3418 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
3419 // (Top was chosen because it works smoothly with passes like GCM.)
3420 //
3421 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
3422 // the type of random VM bits like TLS references.) Since it is always the
3423 // first non-Bot memory slice, some low-level loops use it to initialize an
3424 // index variable: for (i = AliasIdxRaw; i < req(); i++).
3425 //
3426 //
3427 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
3428 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
3429 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
3430 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
3431 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
3432 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
3433 //
3434 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
3435 // really that different from the other memory inputs. An abbreviation called
3436 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
3437 //
3438 //
3439 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
3440 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
3441 // that "emerges though" the base memory will be marked as excluding the alias types
3442 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
3443 //
3444 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
3445 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
3446 //
3447 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
3448 // (It is currently unimplemented.) As you can see, the resulting merge is
3449 // actually a disjoint union of memory states, rather than an overlay.
3450 //
3452 //------------------------------MergeMemNode-----------------------------------
3453 Node* MergeMemNode::make_empty_memory() {
3454 Node* empty_memory = (Node*) Compile::current()->top();
3455 assert(empty_memory->is_top(), "correct sentinel identity");
3456 return empty_memory;
3457 }
3459 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
3460 init_class_id(Class_MergeMem);
3461 // all inputs are nullified in Node::Node(int)
3462 // set_input(0, NULL); // no control input
3464 // Initialize the edges uniformly to top, for starters.
3465 Node* empty_mem = make_empty_memory();
3466 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
3467 init_req(i,empty_mem);
3468 }
3469 assert(empty_memory() == empty_mem, "");
3471 if( new_base != NULL && new_base->is_MergeMem() ) {
3472 MergeMemNode* mdef = new_base->as_MergeMem();
3473 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
3474 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
3475 mms.set_memory(mms.memory2());
3476 }
3477 assert(base_memory() == mdef->base_memory(), "");
3478 } else {
3479 set_base_memory(new_base);
3480 }
3481 }
3483 // Make a new, untransformed MergeMem with the same base as 'mem'.
3484 // If mem is itself a MergeMem, populate the result with the same edges.
3485 MergeMemNode* MergeMemNode::make(Compile* C, Node* mem) {
3486 return new(C, 1+Compile::AliasIdxRaw) MergeMemNode(mem);
3487 }
3489 //------------------------------cmp--------------------------------------------
3490 uint MergeMemNode::hash() const { return NO_HASH; }
3491 uint MergeMemNode::cmp( const Node &n ) const {
3492 return (&n == this); // Always fail except on self
3493 }
3495 //------------------------------Identity---------------------------------------
3496 Node* MergeMemNode::Identity(PhaseTransform *phase) {
3497 // Identity if this merge point does not record any interesting memory
3498 // disambiguations.
3499 Node* base_mem = base_memory();
3500 Node* empty_mem = empty_memory();
3501 if (base_mem != empty_mem) { // Memory path is not dead?
3502 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3503 Node* mem = in(i);
3504 if (mem != empty_mem && mem != base_mem) {
3505 return this; // Many memory splits; no change
3506 }
3507 }
3508 }
3509 return base_mem; // No memory splits; ID on the one true input
3510 }
3512 //------------------------------Ideal------------------------------------------
3513 // This method is invoked recursively on chains of MergeMem nodes
3514 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3515 // Remove chain'd MergeMems
3516 //
3517 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
3518 // relative to the "in(Bot)". Since we are patching both at the same time,
3519 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
3520 // but rewrite each "in(i)" relative to the new "in(Bot)".
3521 Node *progress = NULL;
3524 Node* old_base = base_memory();
3525 Node* empty_mem = empty_memory();
3526 if (old_base == empty_mem)
3527 return NULL; // Dead memory path.
3529 MergeMemNode* old_mbase;
3530 if (old_base != NULL && old_base->is_MergeMem())
3531 old_mbase = old_base->as_MergeMem();
3532 else
3533 old_mbase = NULL;
3534 Node* new_base = old_base;
3536 // simplify stacked MergeMems in base memory
3537 if (old_mbase) new_base = old_mbase->base_memory();
3539 // the base memory might contribute new slices beyond my req()
3540 if (old_mbase) grow_to_match(old_mbase);
3542 // Look carefully at the base node if it is a phi.
3543 PhiNode* phi_base;
3544 if (new_base != NULL && new_base->is_Phi())
3545 phi_base = new_base->as_Phi();
3546 else
3547 phi_base = NULL;
3549 Node* phi_reg = NULL;
3550 uint phi_len = (uint)-1;
3551 if (phi_base != NULL && !phi_base->is_copy()) {
3552 // do not examine phi if degraded to a copy
3553 phi_reg = phi_base->region();
3554 phi_len = phi_base->req();
3555 // see if the phi is unfinished
3556 for (uint i = 1; i < phi_len; i++) {
3557 if (phi_base->in(i) == NULL) {
3558 // incomplete phi; do not look at it yet!
3559 phi_reg = NULL;
3560 phi_len = (uint)-1;
3561 break;
3562 }
3563 }
3564 }
3566 // Note: We do not call verify_sparse on entry, because inputs
3567 // can normalize to the base_memory via subsume_node or similar
3568 // mechanisms. This method repairs that damage.
3570 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
3572 // Look at each slice.
3573 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3574 Node* old_in = in(i);
3575 // calculate the old memory value
3576 Node* old_mem = old_in;
3577 if (old_mem == empty_mem) old_mem = old_base;
3578 assert(old_mem == memory_at(i), "");
3580 // maybe update (reslice) the old memory value
3582 // simplify stacked MergeMems
3583 Node* new_mem = old_mem;
3584 MergeMemNode* old_mmem;
3585 if (old_mem != NULL && old_mem->is_MergeMem())
3586 old_mmem = old_mem->as_MergeMem();
3587 else
3588 old_mmem = NULL;
3589 if (old_mmem == this) {
3590 // This can happen if loops break up and safepoints disappear.
3591 // A merge of BotPtr (default) with a RawPtr memory derived from a
3592 // safepoint can be rewritten to a merge of the same BotPtr with
3593 // the BotPtr phi coming into the loop. If that phi disappears
3594 // also, we can end up with a self-loop of the mergemem.
3595 // In general, if loops degenerate and memory effects disappear,
3596 // a mergemem can be left looking at itself. This simply means
3597 // that the mergemem's default should be used, since there is
3598 // no longer any apparent effect on this slice.
3599 // Note: If a memory slice is a MergeMem cycle, it is unreachable
3600 // from start. Update the input to TOP.
3601 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
3602 }
3603 else if (old_mmem != NULL) {
3604 new_mem = old_mmem->memory_at(i);
3605 }
3606 // else preceeding memory was not a MergeMem
3608 // replace equivalent phis (unfortunately, they do not GVN together)
3609 if (new_mem != NULL && new_mem != new_base &&
3610 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) {
3611 if (new_mem->is_Phi()) {
3612 PhiNode* phi_mem = new_mem->as_Phi();
3613 for (uint i = 1; i < phi_len; i++) {
3614 if (phi_base->in(i) != phi_mem->in(i)) {
3615 phi_mem = NULL;
3616 break;
3617 }
3618 }
3619 if (phi_mem != NULL) {
3620 // equivalent phi nodes; revert to the def
3621 new_mem = new_base;
3622 }
3623 }
3624 }
3626 // maybe store down a new value
3627 Node* new_in = new_mem;
3628 if (new_in == new_base) new_in = empty_mem;
3630 if (new_in != old_in) {
3631 // Warning: Do not combine this "if" with the previous "if"
3632 // A memory slice might have be be rewritten even if it is semantically
3633 // unchanged, if the base_memory value has changed.
3634 set_req(i, new_in);
3635 progress = this; // Report progress
3636 }
3637 }
3639 if (new_base != old_base) {
3640 set_req(Compile::AliasIdxBot, new_base);
3641 // Don't use set_base_memory(new_base), because we need to update du.
3642 assert(base_memory() == new_base, "");
3643 progress = this;
3644 }
3646 if( base_memory() == this ) {
3647 // a self cycle indicates this memory path is dead
3648 set_req(Compile::AliasIdxBot, empty_mem);
3649 }
3651 // Resolve external cycles by calling Ideal on a MergeMem base_memory
3652 // Recursion must occur after the self cycle check above
3653 if( base_memory()->is_MergeMem() ) {
3654 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
3655 Node *m = phase->transform(new_mbase); // Rollup any cycles
3656 if( m != NULL && (m->is_top() ||
3657 m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem) ) {
3658 // propagate rollup of dead cycle to self
3659 set_req(Compile::AliasIdxBot, empty_mem);
3660 }
3661 }
3663 if( base_memory() == empty_mem ) {
3664 progress = this;
3665 // Cut inputs during Parse phase only.
3666 // During Optimize phase a dead MergeMem node will be subsumed by Top.
3667 if( !can_reshape ) {
3668 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3669 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
3670 }
3671 }
3672 }
3674 if( !progress && base_memory()->is_Phi() && can_reshape ) {
3675 // Check if PhiNode::Ideal's "Split phis through memory merges"
3676 // transform should be attempted. Look for this->phi->this cycle.
3677 uint merge_width = req();
3678 if (merge_width > Compile::AliasIdxRaw) {
3679 PhiNode* phi = base_memory()->as_Phi();
3680 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
3681 if (phi->in(i) == this) {
3682 phase->is_IterGVN()->_worklist.push(phi);
3683 break;
3684 }
3685 }
3686 }
3687 }
3689 assert(progress || verify_sparse(), "please, no dups of base");
3690 return progress;
3691 }
3693 //-------------------------set_base_memory-------------------------------------
3694 void MergeMemNode::set_base_memory(Node *new_base) {
3695 Node* empty_mem = empty_memory();
3696 set_req(Compile::AliasIdxBot, new_base);
3697 assert(memory_at(req()) == new_base, "must set default memory");
3698 // Clear out other occurrences of new_base:
3699 if (new_base != empty_mem) {
3700 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3701 if (in(i) == new_base) set_req(i, empty_mem);
3702 }
3703 }
3704 }
3706 //------------------------------out_RegMask------------------------------------
3707 const RegMask &MergeMemNode::out_RegMask() const {
3708 return RegMask::Empty;
3709 }
3711 //------------------------------dump_spec--------------------------------------
3712 #ifndef PRODUCT
3713 void MergeMemNode::dump_spec(outputStream *st) const {
3714 st->print(" {");
3715 Node* base_mem = base_memory();
3716 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
3717 Node* mem = memory_at(i);
3718 if (mem == base_mem) { st->print(" -"); continue; }
3719 st->print( " N%d:", mem->_idx );
3720 Compile::current()->get_adr_type(i)->dump_on(st);
3721 }
3722 st->print(" }");
3723 }
3724 #endif // !PRODUCT
3727 #ifdef ASSERT
3728 static bool might_be_same(Node* a, Node* b) {
3729 if (a == b) return true;
3730 if (!(a->is_Phi() || b->is_Phi())) return false;
3731 // phis shift around during optimization
3732 return true; // pretty stupid...
3733 }
3735 // verify a narrow slice (either incoming or outgoing)
3736 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
3737 if (!VerifyAliases) return; // don't bother to verify unless requested
3738 if (is_error_reported()) return; // muzzle asserts when debugging an error
3739 if (Node::in_dump()) return; // muzzle asserts when printing
3740 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
3741 assert(n != NULL, "");
3742 // Elide intervening MergeMem's
3743 while (n->is_MergeMem()) {
3744 n = n->as_MergeMem()->memory_at(alias_idx);
3745 }
3746 Compile* C = Compile::current();
3747 const TypePtr* n_adr_type = n->adr_type();
3748 if (n == m->empty_memory()) {
3749 // Implicit copy of base_memory()
3750 } else if (n_adr_type != TypePtr::BOTTOM) {
3751 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type");
3752 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
3753 } else {
3754 // A few places like make_runtime_call "know" that VM calls are narrow,
3755 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
3756 bool expected_wide_mem = false;
3757 if (n == m->base_memory()) {
3758 expected_wide_mem = true;
3759 } else if (alias_idx == Compile::AliasIdxRaw ||
3760 n == m->memory_at(Compile::AliasIdxRaw)) {
3761 expected_wide_mem = true;
3762 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
3763 // memory can "leak through" calls on channels that
3764 // are write-once. Allow this also.
3765 expected_wide_mem = true;
3766 }
3767 assert(expected_wide_mem, "expected narrow slice replacement");
3768 }
3769 }
3770 #else // !ASSERT
3771 #define verify_memory_slice(m,i,n) (0) // PRODUCT version is no-op
3772 #endif
3775 //-----------------------------memory_at---------------------------------------
3776 Node* MergeMemNode::memory_at(uint alias_idx) const {
3777 assert(alias_idx >= Compile::AliasIdxRaw ||
3778 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0,
3779 "must avoid base_memory and AliasIdxTop");
3781 // Otherwise, it is a narrow slice.
3782 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
3783 Compile *C = Compile::current();
3784 if (is_empty_memory(n)) {
3785 // the array is sparse; empty slots are the "top" node
3786 n = base_memory();
3787 assert(Node::in_dump()
3788 || n == NULL || n->bottom_type() == Type::TOP
3789 || n->adr_type() == TypePtr::BOTTOM
3790 || n->adr_type() == TypeRawPtr::BOTTOM
3791 || Compile::current()->AliasLevel() == 0,
3792 "must be a wide memory");
3793 // AliasLevel == 0 if we are organizing the memory states manually.
3794 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
3795 } else {
3796 // make sure the stored slice is sane
3797 #ifdef ASSERT
3798 if (is_error_reported() || Node::in_dump()) {
3799 } else if (might_be_same(n, base_memory())) {
3800 // Give it a pass: It is a mostly harmless repetition of the base.
3801 // This can arise normally from node subsumption during optimization.
3802 } else {
3803 verify_memory_slice(this, alias_idx, n);
3804 }
3805 #endif
3806 }
3807 return n;
3808 }
3810 //---------------------------set_memory_at-------------------------------------
3811 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
3812 verify_memory_slice(this, alias_idx, n);
3813 Node* empty_mem = empty_memory();
3814 if (n == base_memory()) n = empty_mem; // collapse default
3815 uint need_req = alias_idx+1;
3816 if (req() < need_req) {
3817 if (n == empty_mem) return; // already the default, so do not grow me
3818 // grow the sparse array
3819 do {
3820 add_req(empty_mem);
3821 } while (req() < need_req);
3822 }
3823 set_req( alias_idx, n );
3824 }
3828 //--------------------------iteration_setup------------------------------------
3829 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
3830 if (other != NULL) {
3831 grow_to_match(other);
3832 // invariant: the finite support of mm2 is within mm->req()
3833 #ifdef ASSERT
3834 for (uint i = req(); i < other->req(); i++) {
3835 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
3836 }
3837 #endif
3838 }
3839 // Replace spurious copies of base_memory by top.
3840 Node* base_mem = base_memory();
3841 if (base_mem != NULL && !base_mem->is_top()) {
3842 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
3843 if (in(i) == base_mem)
3844 set_req(i, empty_memory());
3845 }
3846 }
3847 }
3849 //---------------------------grow_to_match-------------------------------------
3850 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
3851 Node* empty_mem = empty_memory();
3852 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
3853 // look for the finite support of the other memory
3854 for (uint i = other->req(); --i >= req(); ) {
3855 if (other->in(i) != empty_mem) {
3856 uint new_len = i+1;
3857 while (req() < new_len) add_req(empty_mem);
3858 break;
3859 }
3860 }
3861 }
3863 //---------------------------verify_sparse-------------------------------------
3864 #ifndef PRODUCT
3865 bool MergeMemNode::verify_sparse() const {
3866 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
3867 Node* base_mem = base_memory();
3868 // The following can happen in degenerate cases, since empty==top.
3869 if (is_empty_memory(base_mem)) return true;
3870 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3871 assert(in(i) != NULL, "sane slice");
3872 if (in(i) == base_mem) return false; // should have been the sentinel value!
3873 }
3874 return true;
3875 }
3877 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
3878 Node* n;
3879 n = mm->in(idx);
3880 if (mem == n) return true; // might be empty_memory()
3881 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
3882 if (mem == n) return true;
3883 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) {
3884 if (mem == n) return true;
3885 if (n == NULL) break;
3886 }
3887 return false;
3888 }
3889 #endif // !PRODUCT