Fri, 12 Feb 2010 15:27:36 -0800
Merge
1 /*
2 * Copyright 1997-2009 Sun Microsystems, Inc. All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
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 *start_mem = phase->C->start()->proj_out(TypeFunc::Memory);
98 Node *prev = NULL;
99 Node *result = mchain;
100 while (prev != result) {
101 prev = result;
102 if (result == start_mem)
103 break; // hit one of our sentinels
104 // skip over a call which does not affect this memory slice
105 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {
106 Node *proj_in = result->in(0);
107 if (proj_in->is_Allocate() && proj_in->_idx == instance_id) {
108 break; // hit one of our sentinels
109 } else if (proj_in->is_Call()) {
110 CallNode *call = proj_in->as_Call();
111 if (!call->may_modify(t_adr, phase)) {
112 result = call->in(TypeFunc::Memory);
113 }
114 } else if (proj_in->is_Initialize()) {
115 AllocateNode* alloc = proj_in->as_Initialize()->allocation();
116 // Stop if this is the initialization for the object instance which
117 // which contains this memory slice, otherwise skip over it.
118 if (alloc != NULL && alloc->_idx != instance_id) {
119 result = proj_in->in(TypeFunc::Memory);
120 }
121 } else if (proj_in->is_MemBar()) {
122 result = proj_in->in(TypeFunc::Memory);
123 } else {
124 assert(false, "unexpected projection");
125 }
126 } else if (result->is_ClearArray()) {
127 if (!ClearArrayNode::step_through(&result, instance_id, phase)) {
128 // Can not bypass initialization of the instance
129 // we are looking for.
130 break;
131 }
132 // Otherwise skip it (the call updated 'result' value).
133 } else if (result->is_MergeMem()) {
134 result = step_through_mergemem(phase, result->as_MergeMem(), t_adr, NULL, tty);
135 }
136 }
137 return result;
138 }
140 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, PhaseGVN *phase) {
141 const TypeOopPtr *t_oop = t_adr->isa_oopptr();
142 bool is_instance = (t_oop != NULL) && t_oop->is_known_instance_field();
143 PhaseIterGVN *igvn = phase->is_IterGVN();
144 Node *result = mchain;
145 result = optimize_simple_memory_chain(result, t_adr, phase);
146 if (is_instance && igvn != NULL && result->is_Phi()) {
147 PhiNode *mphi = result->as_Phi();
148 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
149 const TypePtr *t = mphi->adr_type();
150 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
151 t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
152 t->is_oopptr()->cast_to_exactness(true)
153 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
154 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop) {
155 // clone the Phi with our address type
156 result = mphi->split_out_instance(t_adr, igvn);
157 } else {
158 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain");
159 }
160 }
161 return result;
162 }
164 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) {
165 uint alias_idx = phase->C->get_alias_index(tp);
166 Node *mem = mmem;
167 #ifdef ASSERT
168 {
169 // Check that current type is consistent with the alias index used during graph construction
170 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
171 bool consistent = adr_check == NULL || adr_check->empty() ||
172 phase->C->must_alias(adr_check, alias_idx );
173 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
174 if( !consistent && adr_check != NULL && !adr_check->empty() &&
175 tp->isa_aryptr() && tp->offset() == Type::OffsetBot &&
176 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot &&
177 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() ||
178 adr_check->offset() == oopDesc::klass_offset_in_bytes() ||
179 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) {
180 // don't assert if it is dead code.
181 consistent = true;
182 }
183 if( !consistent ) {
184 st->print("alias_idx==%d, adr_check==", alias_idx);
185 if( adr_check == NULL ) {
186 st->print("NULL");
187 } else {
188 adr_check->dump();
189 }
190 st->cr();
191 print_alias_types();
192 assert(consistent, "adr_check must match alias idx");
193 }
194 }
195 #endif
196 // TypeInstPtr::NOTNULL+any is an OOP with unknown offset - generally
197 // means an array I have not precisely typed yet. Do not do any
198 // alias stuff with it any time soon.
199 const TypeOopPtr *tinst = tp->isa_oopptr();
200 if( tp->base() != Type::AnyPtr &&
201 !(tinst &&
202 tinst->klass()->is_java_lang_Object() &&
203 tinst->offset() == Type::OffsetBot) ) {
204 // compress paths and change unreachable cycles to TOP
205 // If not, we can update the input infinitely along a MergeMem cycle
206 // Equivalent code in PhiNode::Ideal
207 Node* m = phase->transform(mmem);
208 // If transformed to a MergeMem, get the desired slice
209 // Otherwise the returned node represents memory for every slice
210 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
211 // Update input if it is progress over what we have now
212 }
213 return mem;
214 }
216 //--------------------------Ideal_common---------------------------------------
217 // Look for degenerate control and memory inputs. Bypass MergeMem inputs.
218 // Unhook non-raw memories from complete (macro-expanded) initializations.
219 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
220 // If our control input is a dead region, kill all below the region
221 Node *ctl = in(MemNode::Control);
222 if (ctl && remove_dead_region(phase, can_reshape))
223 return this;
224 ctl = in(MemNode::Control);
225 // Don't bother trying to transform a dead node
226 if( ctl && ctl->is_top() ) return NodeSentinel;
228 PhaseIterGVN *igvn = phase->is_IterGVN();
229 // Wait if control on the worklist.
230 if (ctl && can_reshape && igvn != NULL) {
231 Node* bol = NULL;
232 Node* cmp = NULL;
233 if (ctl->in(0)->is_If()) {
234 assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity");
235 bol = ctl->in(0)->in(1);
236 if (bol->is_Bool())
237 cmp = ctl->in(0)->in(1)->in(1);
238 }
239 if (igvn->_worklist.member(ctl) ||
240 (bol != NULL && igvn->_worklist.member(bol)) ||
241 (cmp != NULL && igvn->_worklist.member(cmp)) ) {
242 // This control path may be dead.
243 // Delay this memory node transformation until the control is processed.
244 phase->is_IterGVN()->_worklist.push(this);
245 return NodeSentinel; // caller will return NULL
246 }
247 }
248 // Ignore if memory is dead, or self-loop
249 Node *mem = in(MemNode::Memory);
250 if( phase->type( mem ) == Type::TOP ) return NodeSentinel; // caller will return NULL
251 assert( mem != this, "dead loop in MemNode::Ideal" );
253 Node *address = in(MemNode::Address);
254 const Type *t_adr = phase->type( address );
255 if( t_adr == Type::TOP ) return NodeSentinel; // caller will return NULL
257 if( can_reshape && igvn != NULL &&
258 (igvn->_worklist.member(address) || phase->type(address) != adr_type()) ) {
259 // The address's base and type may change when the address is processed.
260 // Delay this mem node transformation until the address is processed.
261 phase->is_IterGVN()->_worklist.push(this);
262 return NodeSentinel; // caller will return NULL
263 }
265 // Do NOT remove or optimize the next lines: ensure a new alias index
266 // is allocated for an oop pointer type before Escape Analysis.
267 // Note: C++ will not remove it since the call has side effect.
268 if ( t_adr->isa_oopptr() ) {
269 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr());
270 }
272 #ifdef ASSERT
273 Node* base = NULL;
274 if (address->is_AddP())
275 base = address->in(AddPNode::Base);
276 assert(base == NULL || t_adr->isa_rawptr() ||
277 !phase->type(base)->higher_equal(TypePtr::NULL_PTR), "NULL+offs not RAW address?");
278 #endif
280 // Avoid independent memory operations
281 Node* old_mem = mem;
283 // The code which unhooks non-raw memories from complete (macro-expanded)
284 // initializations was removed. After macro-expansion all stores catched
285 // by Initialize node became raw stores and there is no information
286 // which memory slices they modify. So it is unsafe to move any memory
287 // operation above these stores. Also in most cases hooked non-raw memories
288 // were already unhooked by using information from detect_ptr_independence()
289 // and find_previous_store().
291 if (mem->is_MergeMem()) {
292 MergeMemNode* mmem = mem->as_MergeMem();
293 const TypePtr *tp = t_adr->is_ptr();
295 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
296 }
298 if (mem != old_mem) {
299 set_req(MemNode::Memory, mem);
300 if (phase->type( mem ) == Type::TOP) return NodeSentinel;
301 return this;
302 }
304 // let the subclass continue analyzing...
305 return NULL;
306 }
308 // Helper function for proving some simple control dominations.
309 // Attempt to prove that all control inputs of 'dom' dominate 'sub'.
310 // Already assumes that 'dom' is available at 'sub', and that 'sub'
311 // is not a constant (dominated by the method's StartNode).
312 // Used by MemNode::find_previous_store to prove that the
313 // control input of a memory operation predates (dominates)
314 // an allocation it wants to look past.
315 bool MemNode::all_controls_dominate(Node* dom, Node* sub) {
316 if (dom == NULL || dom->is_top() || sub == NULL || sub->is_top())
317 return false; // Conservative answer for dead code
319 // Check 'dom'. Skip Proj and CatchProj nodes.
320 dom = dom->find_exact_control(dom);
321 if (dom == NULL || dom->is_top())
322 return false; // Conservative answer for dead code
324 if (dom == sub) {
325 // For the case when, for example, 'sub' is Initialize and the original
326 // 'dom' is Proj node of the 'sub'.
327 return false;
328 }
330 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub)
331 return true;
333 // 'dom' dominates 'sub' if its control edge and control edges
334 // of all its inputs dominate or equal to sub's control edge.
336 // Currently 'sub' is either Allocate, Initialize or Start nodes.
337 // Or Region for the check in LoadNode::Ideal();
338 // 'sub' should have sub->in(0) != NULL.
339 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() ||
340 sub->is_Region(), "expecting only these nodes");
342 // Get control edge of 'sub'.
343 Node* orig_sub = sub;
344 sub = sub->find_exact_control(sub->in(0));
345 if (sub == NULL || sub->is_top())
346 return false; // Conservative answer for dead code
348 assert(sub->is_CFG(), "expecting control");
350 if (sub == dom)
351 return true;
353 if (sub->is_Start() || sub->is_Root())
354 return false;
356 {
357 // Check all control edges of 'dom'.
359 ResourceMark rm;
360 Arena* arena = Thread::current()->resource_area();
361 Node_List nlist(arena);
362 Unique_Node_List dom_list(arena);
364 dom_list.push(dom);
365 bool only_dominating_controls = false;
367 for (uint next = 0; next < dom_list.size(); next++) {
368 Node* n = dom_list.at(next);
369 if (n == orig_sub)
370 return false; // One of dom's inputs dominated by sub.
371 if (!n->is_CFG() && n->pinned()) {
372 // Check only own control edge for pinned non-control nodes.
373 n = n->find_exact_control(n->in(0));
374 if (n == NULL || n->is_top())
375 return false; // Conservative answer for dead code
376 assert(n->is_CFG(), "expecting control");
377 dom_list.push(n);
378 } else if (n->is_Con() || n->is_Start() || n->is_Root()) {
379 only_dominating_controls = true;
380 } else if (n->is_CFG()) {
381 if (n->dominates(sub, nlist))
382 only_dominating_controls = true;
383 else
384 return false;
385 } else {
386 // First, own control edge.
387 Node* m = n->find_exact_control(n->in(0));
388 if (m != NULL) {
389 if (m->is_top())
390 return false; // Conservative answer for dead code
391 dom_list.push(m);
392 }
393 // Now, the rest of edges.
394 uint cnt = n->req();
395 for (uint i = 1; i < cnt; i++) {
396 m = n->find_exact_control(n->in(i));
397 if (m == NULL || m->is_top())
398 continue;
399 dom_list.push(m);
400 }
401 }
402 }
403 return only_dominating_controls;
404 }
405 }
407 //---------------------detect_ptr_independence---------------------------------
408 // Used by MemNode::find_previous_store to prove that two base
409 // pointers are never equal.
410 // The pointers are accompanied by their associated allocations,
411 // if any, which have been previously discovered by the caller.
412 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
413 Node* p2, AllocateNode* a2,
414 PhaseTransform* phase) {
415 // Attempt to prove that these two pointers cannot be aliased.
416 // They may both manifestly be allocations, and they should differ.
417 // Or, if they are not both allocations, they can be distinct constants.
418 // Otherwise, one is an allocation and the other a pre-existing value.
419 if (a1 == NULL && a2 == NULL) { // neither an allocation
420 return (p1 != p2) && p1->is_Con() && p2->is_Con();
421 } else if (a1 != NULL && a2 != NULL) { // both allocations
422 return (a1 != a2);
423 } else if (a1 != NULL) { // one allocation a1
424 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.)
425 return all_controls_dominate(p2, a1);
426 } else { //(a2 != NULL) // one allocation a2
427 return all_controls_dominate(p1, a2);
428 }
429 return false;
430 }
433 // The logic for reordering loads and stores uses four steps:
434 // (a) Walk carefully past stores and initializations which we
435 // can prove are independent of this load.
436 // (b) Observe that the next memory state makes an exact match
437 // with self (load or store), and locate the relevant store.
438 // (c) Ensure that, if we were to wire self directly to the store,
439 // the optimizer would fold it up somehow.
440 // (d) Do the rewiring, and return, depending on some other part of
441 // the optimizer to fold up the load.
442 // This routine handles steps (a) and (b). Steps (c) and (d) are
443 // specific to loads and stores, so they are handled by the callers.
444 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.)
445 //
446 Node* MemNode::find_previous_store(PhaseTransform* phase) {
447 Node* ctrl = in(MemNode::Control);
448 Node* adr = in(MemNode::Address);
449 intptr_t offset = 0;
450 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
451 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase);
453 if (offset == Type::OffsetBot)
454 return NULL; // cannot unalias unless there are precise offsets
456 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr();
458 intptr_t size_in_bytes = memory_size();
460 Node* mem = in(MemNode::Memory); // start searching here...
462 int cnt = 50; // Cycle limiter
463 for (;;) { // While we can dance past unrelated stores...
464 if (--cnt < 0) break; // Caught in cycle or a complicated dance?
466 if (mem->is_Store()) {
467 Node* st_adr = mem->in(MemNode::Address);
468 intptr_t st_offset = 0;
469 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
470 if (st_base == NULL)
471 break; // inscrutable pointer
472 if (st_offset != offset && st_offset != Type::OffsetBot) {
473 const int MAX_STORE = BytesPerLong;
474 if (st_offset >= offset + size_in_bytes ||
475 st_offset <= offset - MAX_STORE ||
476 st_offset <= offset - mem->as_Store()->memory_size()) {
477 // Success: The offsets are provably independent.
478 // (You may ask, why not just test st_offset != offset and be done?
479 // The answer is that stores of different sizes can co-exist
480 // in the same sequence of RawMem effects. We sometimes initialize
481 // a whole 'tile' of array elements with a single jint or jlong.)
482 mem = mem->in(MemNode::Memory);
483 continue; // (a) advance through independent store memory
484 }
485 }
486 if (st_base != base &&
487 detect_ptr_independence(base, alloc,
488 st_base,
489 AllocateNode::Ideal_allocation(st_base, phase),
490 phase)) {
491 // Success: The bases are provably independent.
492 mem = mem->in(MemNode::Memory);
493 continue; // (a) advance through independent store memory
494 }
496 // (b) At this point, if the bases or offsets do not agree, we lose,
497 // since we have not managed to prove 'this' and 'mem' independent.
498 if (st_base == base && st_offset == offset) {
499 return mem; // let caller handle steps (c), (d)
500 }
502 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
503 InitializeNode* st_init = mem->in(0)->as_Initialize();
504 AllocateNode* st_alloc = st_init->allocation();
505 if (st_alloc == NULL)
506 break; // something degenerated
507 bool known_identical = false;
508 bool known_independent = false;
509 if (alloc == st_alloc)
510 known_identical = true;
511 else if (alloc != NULL)
512 known_independent = true;
513 else if (all_controls_dominate(this, st_alloc))
514 known_independent = true;
516 if (known_independent) {
517 // The bases are provably independent: Either they are
518 // manifestly distinct allocations, or else the control
519 // of this load dominates the store's allocation.
520 int alias_idx = phase->C->get_alias_index(adr_type());
521 if (alias_idx == Compile::AliasIdxRaw) {
522 mem = st_alloc->in(TypeFunc::Memory);
523 } else {
524 mem = st_init->memory(alias_idx);
525 }
526 continue; // (a) advance through independent store memory
527 }
529 // (b) at this point, if we are not looking at a store initializing
530 // the same allocation we are loading from, we lose.
531 if (known_identical) {
532 // From caller, can_see_stored_value will consult find_captured_store.
533 return mem; // let caller handle steps (c), (d)
534 }
536 } else if (addr_t != NULL && addr_t->is_known_instance_field()) {
537 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
538 if (mem->is_Proj() && mem->in(0)->is_Call()) {
539 CallNode *call = mem->in(0)->as_Call();
540 if (!call->may_modify(addr_t, phase)) {
541 mem = call->in(TypeFunc::Memory);
542 continue; // (a) advance through independent call memory
543 }
544 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) {
545 mem = mem->in(0)->in(TypeFunc::Memory);
546 continue; // (a) advance through independent MemBar memory
547 } else if (mem->is_ClearArray()) {
548 if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) {
549 // (the call updated 'mem' value)
550 continue; // (a) advance through independent allocation memory
551 } else {
552 // Can not bypass initialization of the instance
553 // we are looking for.
554 return mem;
555 }
556 } else if (mem->is_MergeMem()) {
557 int alias_idx = phase->C->get_alias_index(adr_type());
558 mem = mem->as_MergeMem()->memory_at(alias_idx);
559 continue; // (a) advance through independent MergeMem memory
560 }
561 }
563 // Unless there is an explicit 'continue', we must bail out here,
564 // because 'mem' is an inscrutable memory state (e.g., a call).
565 break;
566 }
568 return NULL; // bail out
569 }
571 //----------------------calculate_adr_type-------------------------------------
572 // Helper function. Notices when the given type of address hits top or bottom.
573 // Also, asserts a cross-check of the type against the expected address type.
574 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
575 if (t == Type::TOP) return NULL; // does not touch memory any more?
576 #ifdef PRODUCT
577 cross_check = NULL;
578 #else
579 if (!VerifyAliases || is_error_reported() || Node::in_dump()) cross_check = NULL;
580 #endif
581 const TypePtr* tp = t->isa_ptr();
582 if (tp == NULL) {
583 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
584 return TypePtr::BOTTOM; // touches lots of memory
585 } else {
586 #ifdef ASSERT
587 // %%%% [phh] We don't check the alias index if cross_check is
588 // TypeRawPtr::BOTTOM. Needs to be investigated.
589 if (cross_check != NULL &&
590 cross_check != TypePtr::BOTTOM &&
591 cross_check != TypeRawPtr::BOTTOM) {
592 // Recheck the alias index, to see if it has changed (due to a bug).
593 Compile* C = Compile::current();
594 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
595 "must stay in the original alias category");
596 // The type of the address must be contained in the adr_type,
597 // disregarding "null"-ness.
598 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
599 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
600 assert(cross_check->meet(tp_notnull) == cross_check,
601 "real address must not escape from expected memory type");
602 }
603 #endif
604 return tp;
605 }
606 }
608 //------------------------adr_phi_is_loop_invariant----------------------------
609 // A helper function for Ideal_DU_postCCP to check if a Phi in a counted
610 // loop is loop invariant. Make a quick traversal of Phi and associated
611 // CastPP nodes, looking to see if they are a closed group within the loop.
612 bool MemNode::adr_phi_is_loop_invariant(Node* adr_phi, Node* cast) {
613 // The idea is that the phi-nest must boil down to only CastPP nodes
614 // with the same data. This implies that any path into the loop already
615 // includes such a CastPP, and so the original cast, whatever its input,
616 // must be covered by an equivalent cast, with an earlier control input.
617 ResourceMark rm;
619 // The loop entry input of the phi should be the unique dominating
620 // node for every Phi/CastPP in the loop.
621 Unique_Node_List closure;
622 closure.push(adr_phi->in(LoopNode::EntryControl));
624 // Add the phi node and the cast to the worklist.
625 Unique_Node_List worklist;
626 worklist.push(adr_phi);
627 if( cast != NULL ){
628 if( !cast->is_ConstraintCast() ) return false;
629 worklist.push(cast);
630 }
632 // Begin recursive walk of phi nodes.
633 while( worklist.size() ){
634 // Take a node off the worklist
635 Node *n = worklist.pop();
636 if( !closure.member(n) ){
637 // Add it to the closure.
638 closure.push(n);
639 // Make a sanity check to ensure we don't waste too much time here.
640 if( closure.size() > 20) return false;
641 // This node is OK if:
642 // - it is a cast of an identical value
643 // - or it is a phi node (then we add its inputs to the worklist)
644 // Otherwise, the node is not OK, and we presume the cast is not invariant
645 if( n->is_ConstraintCast() ){
646 worklist.push(n->in(1));
647 } else if( n->is_Phi() ) {
648 for( uint i = 1; i < n->req(); i++ ) {
649 worklist.push(n->in(i));
650 }
651 } else {
652 return false;
653 }
654 }
655 }
657 // Quit when the worklist is empty, and we've found no offending nodes.
658 return true;
659 }
661 //------------------------------Ideal_DU_postCCP-------------------------------
662 // Find any cast-away of null-ness and keep its control. Null cast-aways are
663 // going away in this pass and we need to make this memory op depend on the
664 // gating null check.
665 Node *MemNode::Ideal_DU_postCCP( PhaseCCP *ccp ) {
666 return Ideal_common_DU_postCCP(ccp, this, in(MemNode::Address));
667 }
669 // I tried to leave the CastPP's in. This makes the graph more accurate in
670 // some sense; we get to keep around the knowledge that an oop is not-null
671 // after some test. Alas, the CastPP's interfere with GVN (some values are
672 // the regular oop, some are the CastPP of the oop, all merge at Phi's which
673 // cannot collapse, etc). This cost us 10% on SpecJVM, even when I removed
674 // some of the more trivial cases in the optimizer. Removing more useless
675 // Phi's started allowing Loads to illegally float above null checks. I gave
676 // up on this approach. CNC 10/20/2000
677 // This static method may be called not from MemNode (EncodePNode calls it).
678 // Only the control edge of the node 'n' might be updated.
679 Node *MemNode::Ideal_common_DU_postCCP( PhaseCCP *ccp, Node* n, Node* adr ) {
680 Node *skipped_cast = NULL;
681 // Need a null check? Regular static accesses do not because they are
682 // from constant addresses. Array ops are gated by the range check (which
683 // always includes a NULL check). Just check field ops.
684 if( n->in(MemNode::Control) == NULL ) {
685 // Scan upwards for the highest location we can place this memory op.
686 while( true ) {
687 switch( adr->Opcode() ) {
689 case Op_AddP: // No change to NULL-ness, so peek thru AddP's
690 adr = adr->in(AddPNode::Base);
691 continue;
693 case Op_DecodeN: // No change to NULL-ness, so peek thru
694 adr = adr->in(1);
695 continue;
697 case Op_CastPP:
698 // If the CastPP is useless, just peek on through it.
699 if( ccp->type(adr) == ccp->type(adr->in(1)) ) {
700 // Remember the cast that we've peeked though. If we peek
701 // through more than one, then we end up remembering the highest
702 // one, that is, if in a loop, the one closest to the top.
703 skipped_cast = adr;
704 adr = adr->in(1);
705 continue;
706 }
707 // CastPP is going away in this pass! We need this memory op to be
708 // control-dependent on the test that is guarding the CastPP.
709 ccp->hash_delete(n);
710 n->set_req(MemNode::Control, adr->in(0));
711 ccp->hash_insert(n);
712 return n;
714 case Op_Phi:
715 // Attempt to float above a Phi to some dominating point.
716 if (adr->in(0) != NULL && adr->in(0)->is_CountedLoop()) {
717 // If we've already peeked through a Cast (which could have set the
718 // control), we can't float above a Phi, because the skipped Cast
719 // may not be loop invariant.
720 if (adr_phi_is_loop_invariant(adr, skipped_cast)) {
721 adr = adr->in(1);
722 continue;
723 }
724 }
726 // Intentional fallthrough!
728 // No obvious dominating point. The mem op is pinned below the Phi
729 // by the Phi itself. If the Phi goes away (no true value is merged)
730 // then the mem op can float, but not indefinitely. It must be pinned
731 // behind the controls leading to the Phi.
732 case Op_CheckCastPP:
733 // These usually stick around to change address type, however a
734 // useless one can be elided and we still need to pick up a control edge
735 if (adr->in(0) == NULL) {
736 // This CheckCastPP node has NO control and is likely useless. But we
737 // need check further up the ancestor chain for a control input to keep
738 // the node in place. 4959717.
739 skipped_cast = adr;
740 adr = adr->in(1);
741 continue;
742 }
743 ccp->hash_delete(n);
744 n->set_req(MemNode::Control, adr->in(0));
745 ccp->hash_insert(n);
746 return n;
748 // List of "safe" opcodes; those that implicitly block the memory
749 // op below any null check.
750 case Op_CastX2P: // no null checks on native pointers
751 case Op_Parm: // 'this' pointer is not null
752 case Op_LoadP: // Loading from within a klass
753 case Op_LoadN: // Loading from within a klass
754 case Op_LoadKlass: // Loading from within a klass
755 case Op_LoadNKlass: // Loading from within a klass
756 case Op_ConP: // Loading from a klass
757 case Op_ConN: // Loading from a klass
758 case Op_CreateEx: // Sucking up the guts of an exception oop
759 case Op_Con: // Reading from TLS
760 case Op_CMoveP: // CMoveP is pinned
761 case Op_CMoveN: // CMoveN is pinned
762 break; // No progress
764 case Op_Proj: // Direct call to an allocation routine
765 case Op_SCMemProj: // Memory state from store conditional ops
766 #ifdef ASSERT
767 {
768 assert(adr->as_Proj()->_con == TypeFunc::Parms, "must be return value");
769 const Node* call = adr->in(0);
770 if (call->is_CallJava()) {
771 const CallJavaNode* call_java = call->as_CallJava();
772 const TypeTuple *r = call_java->tf()->range();
773 assert(r->cnt() > TypeFunc::Parms, "must return value");
774 const Type* ret_type = r->field_at(TypeFunc::Parms);
775 assert(ret_type && ret_type->isa_ptr(), "must return pointer");
776 // We further presume that this is one of
777 // new_instance_Java, new_array_Java, or
778 // the like, but do not assert for this.
779 } else if (call->is_Allocate()) {
780 // similar case to new_instance_Java, etc.
781 } else if (!call->is_CallLeaf()) {
782 // Projections from fetch_oop (OSR) are allowed as well.
783 ShouldNotReachHere();
784 }
785 }
786 #endif
787 break;
788 default:
789 ShouldNotReachHere();
790 }
791 break;
792 }
793 }
795 return NULL; // No progress
796 }
799 //=============================================================================
800 uint LoadNode::size_of() const { return sizeof(*this); }
801 uint LoadNode::cmp( const Node &n ) const
802 { return !Type::cmp( _type, ((LoadNode&)n)._type ); }
803 const Type *LoadNode::bottom_type() const { return _type; }
804 uint LoadNode::ideal_reg() const {
805 return Matcher::base2reg[_type->base()];
806 }
808 #ifndef PRODUCT
809 void LoadNode::dump_spec(outputStream *st) const {
810 MemNode::dump_spec(st);
811 if( !Verbose && !WizardMode ) {
812 // standard dump does this in Verbose and WizardMode
813 st->print(" #"); _type->dump_on(st);
814 }
815 }
816 #endif
819 //----------------------------LoadNode::make-----------------------------------
820 // Polymorphic factory method:
821 Node *LoadNode::make( PhaseGVN& gvn, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt ) {
822 Compile* C = gvn.C;
824 // sanity check the alias category against the created node type
825 assert(!(adr_type->isa_oopptr() &&
826 adr_type->offset() == oopDesc::klass_offset_in_bytes()),
827 "use LoadKlassNode instead");
828 assert(!(adr_type->isa_aryptr() &&
829 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
830 "use LoadRangeNode instead");
831 switch (bt) {
832 case T_BOOLEAN: return new (C, 3) LoadUBNode(ctl, mem, adr, adr_type, rt->is_int() );
833 case T_BYTE: return new (C, 3) LoadBNode (ctl, mem, adr, adr_type, rt->is_int() );
834 case T_INT: return new (C, 3) LoadINode (ctl, mem, adr, adr_type, rt->is_int() );
835 case T_CHAR: return new (C, 3) LoadUSNode(ctl, mem, adr, adr_type, rt->is_int() );
836 case T_SHORT: return new (C, 3) LoadSNode (ctl, mem, adr, adr_type, rt->is_int() );
837 case T_LONG: return new (C, 3) LoadLNode (ctl, mem, adr, adr_type, rt->is_long() );
838 case T_FLOAT: return new (C, 3) LoadFNode (ctl, mem, adr, adr_type, rt );
839 case T_DOUBLE: return new (C, 3) LoadDNode (ctl, mem, adr, adr_type, rt );
840 case T_ADDRESS: return new (C, 3) LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr() );
841 case T_OBJECT:
842 #ifdef _LP64
843 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
844 Node* load = gvn.transform(new (C, 3) LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop()));
845 return new (C, 2) DecodeNNode(load, load->bottom_type()->make_ptr());
846 } else
847 #endif
848 {
849 assert(!adr->bottom_type()->is_ptr_to_narrowoop(), "should have got back a narrow oop");
850 return new (C, 3) LoadPNode(ctl, mem, adr, adr_type, rt->is_oopptr());
851 }
852 }
853 ShouldNotReachHere();
854 return (LoadNode*)NULL;
855 }
857 LoadLNode* LoadLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt) {
858 bool require_atomic = true;
859 return new (C, 3) LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), require_atomic);
860 }
865 //------------------------------hash-------------------------------------------
866 uint LoadNode::hash() const {
867 // unroll addition of interesting fields
868 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
869 }
871 //---------------------------can_see_stored_value------------------------------
872 // This routine exists to make sure this set of tests is done the same
873 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
874 // will change the graph shape in a way which makes memory alive twice at the
875 // same time (uses the Oracle model of aliasing), then some
876 // LoadXNode::Identity will fold things back to the equivalence-class model
877 // of aliasing.
878 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const {
879 Node* ld_adr = in(MemNode::Address);
881 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
882 Compile::AliasType* atp = tp != NULL ? phase->C->alias_type(tp) : NULL;
883 if (EliminateAutoBox && atp != NULL && atp->index() >= Compile::AliasIdxRaw &&
884 atp->field() != NULL && !atp->field()->is_volatile()) {
885 uint alias_idx = atp->index();
886 bool final = atp->field()->is_final();
887 Node* result = NULL;
888 Node* current = st;
889 // Skip through chains of MemBarNodes checking the MergeMems for
890 // new states for the slice of this load. Stop once any other
891 // kind of node is encountered. Loads from final memory can skip
892 // through any kind of MemBar but normal loads shouldn't skip
893 // through MemBarAcquire since the could allow them to move out of
894 // a synchronized region.
895 while (current->is_Proj()) {
896 int opc = current->in(0)->Opcode();
897 if ((final && opc == Op_MemBarAcquire) ||
898 opc == Op_MemBarRelease || opc == Op_MemBarCPUOrder) {
899 Node* mem = current->in(0)->in(TypeFunc::Memory);
900 if (mem->is_MergeMem()) {
901 MergeMemNode* merge = mem->as_MergeMem();
902 Node* new_st = merge->memory_at(alias_idx);
903 if (new_st == merge->base_memory()) {
904 // Keep searching
905 current = merge->base_memory();
906 continue;
907 }
908 // Save the new memory state for the slice and fall through
909 // to exit.
910 result = new_st;
911 }
912 }
913 break;
914 }
915 if (result != NULL) {
916 st = result;
917 }
918 }
921 // Loop around twice in the case Load -> Initialize -> Store.
922 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
923 for (int trip = 0; trip <= 1; trip++) {
925 if (st->is_Store()) {
926 Node* st_adr = st->in(MemNode::Address);
927 if (!phase->eqv(st_adr, ld_adr)) {
928 // Try harder before giving up... Match raw and non-raw pointers.
929 intptr_t st_off = 0;
930 AllocateNode* alloc = AllocateNode::Ideal_allocation(st_adr, phase, st_off);
931 if (alloc == NULL) return NULL;
932 intptr_t ld_off = 0;
933 AllocateNode* allo2 = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
934 if (alloc != allo2) return NULL;
935 if (ld_off != st_off) return NULL;
936 // At this point we have proven something like this setup:
937 // A = Allocate(...)
938 // L = LoadQ(, AddP(CastPP(, A.Parm),, #Off))
939 // S = StoreQ(, AddP(, A.Parm , #Off), V)
940 // (Actually, we haven't yet proven the Q's are the same.)
941 // In other words, we are loading from a casted version of
942 // the same pointer-and-offset that we stored to.
943 // Thus, we are able to replace L by V.
944 }
945 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
946 if (store_Opcode() != st->Opcode())
947 return NULL;
948 return st->in(MemNode::ValueIn);
949 }
951 intptr_t offset = 0; // scratch
953 // A load from a freshly-created object always returns zero.
954 // (This can happen after LoadNode::Ideal resets the load's memory input
955 // to find_captured_store, which returned InitializeNode::zero_memory.)
956 if (st->is_Proj() && st->in(0)->is_Allocate() &&
957 st->in(0) == AllocateNode::Ideal_allocation(ld_adr, phase, offset) &&
958 offset >= st->in(0)->as_Allocate()->minimum_header_size()) {
959 // return a zero value for the load's basic type
960 // (This is one of the few places where a generic PhaseTransform
961 // can create new nodes. Think of it as lazily manifesting
962 // virtually pre-existing constants.)
963 return phase->zerocon(memory_type());
964 }
966 // A load from an initialization barrier can match a captured store.
967 if (st->is_Proj() && st->in(0)->is_Initialize()) {
968 InitializeNode* init = st->in(0)->as_Initialize();
969 AllocateNode* alloc = init->allocation();
970 if (alloc != NULL &&
971 alloc == AllocateNode::Ideal_allocation(ld_adr, phase, offset)) {
972 // examine a captured store value
973 st = init->find_captured_store(offset, memory_size(), phase);
974 if (st != NULL)
975 continue; // take one more trip around
976 }
977 }
979 break;
980 }
982 return NULL;
983 }
985 //----------------------is_instance_field_load_with_local_phi------------------
986 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
987 if( in(MemNode::Memory)->is_Phi() && in(MemNode::Memory)->in(0) == ctrl &&
988 in(MemNode::Address)->is_AddP() ) {
989 const TypeOopPtr* t_oop = in(MemNode::Address)->bottom_type()->isa_oopptr();
990 // Only instances.
991 if( t_oop != NULL && t_oop->is_known_instance_field() &&
992 t_oop->offset() != Type::OffsetBot &&
993 t_oop->offset() != Type::OffsetTop) {
994 return true;
995 }
996 }
997 return false;
998 }
1000 //------------------------------Identity---------------------------------------
1001 // Loads are identity if previous store is to same address
1002 Node *LoadNode::Identity( PhaseTransform *phase ) {
1003 // If the previous store-maker is the right kind of Store, and the store is
1004 // to the same address, then we are equal to the value stored.
1005 Node* mem = in(MemNode::Memory);
1006 Node* value = can_see_stored_value(mem, phase);
1007 if( value ) {
1008 // byte, short & char stores truncate naturally.
1009 // A load has to load the truncated value which requires
1010 // some sort of masking operation and that requires an
1011 // Ideal call instead of an Identity call.
1012 if (memory_size() < BytesPerInt) {
1013 // If the input to the store does not fit with the load's result type,
1014 // it must be truncated via an Ideal call.
1015 if (!phase->type(value)->higher_equal(phase->type(this)))
1016 return this;
1017 }
1018 // (This works even when value is a Con, but LoadNode::Value
1019 // usually runs first, producing the singleton type of the Con.)
1020 return value;
1021 }
1023 // Search for an existing data phi which was generated before for the same
1024 // instance's field to avoid infinite generation of phis in a loop.
1025 Node *region = mem->in(0);
1026 if (is_instance_field_load_with_local_phi(region)) {
1027 const TypePtr *addr_t = in(MemNode::Address)->bottom_type()->isa_ptr();
1028 int this_index = phase->C->get_alias_index(addr_t);
1029 int this_offset = addr_t->offset();
1030 int this_id = addr_t->is_oopptr()->instance_id();
1031 const Type* this_type = bottom_type();
1032 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1033 Node* phi = region->fast_out(i);
1034 if (phi->is_Phi() && phi != mem &&
1035 phi->as_Phi()->is_same_inst_field(this_type, this_id, this_index, this_offset)) {
1036 return phi;
1037 }
1038 }
1039 }
1041 return this;
1042 }
1045 // Returns true if the AliasType refers to the field that holds the
1046 // cached box array. Currently only handles the IntegerCache case.
1047 static bool is_autobox_cache(Compile::AliasType* atp) {
1048 if (atp != NULL && atp->field() != NULL) {
1049 ciField* field = atp->field();
1050 ciSymbol* klass = field->holder()->name();
1051 if (field->name() == ciSymbol::cache_field_name() &&
1052 field->holder()->uses_default_loader() &&
1053 klass == ciSymbol::java_lang_Integer_IntegerCache()) {
1054 return true;
1055 }
1056 }
1057 return false;
1058 }
1060 // Fetch the base value in the autobox array
1061 static bool fetch_autobox_base(Compile::AliasType* atp, int& cache_offset) {
1062 if (atp != NULL && atp->field() != NULL) {
1063 ciField* field = atp->field();
1064 ciSymbol* klass = field->holder()->name();
1065 if (field->name() == ciSymbol::cache_field_name() &&
1066 field->holder()->uses_default_loader() &&
1067 klass == ciSymbol::java_lang_Integer_IntegerCache()) {
1068 assert(field->is_constant(), "what?");
1069 ciObjArray* array = field->constant_value().as_object()->as_obj_array();
1070 // Fetch the box object at the base of the array and get its value
1071 ciInstance* box = array->obj_at(0)->as_instance();
1072 ciInstanceKlass* ik = box->klass()->as_instance_klass();
1073 if (ik->nof_nonstatic_fields() == 1) {
1074 // This should be true nonstatic_field_at requires calling
1075 // nof_nonstatic_fields so check it anyway
1076 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1077 cache_offset = c.as_int();
1078 }
1079 return true;
1080 }
1081 }
1082 return false;
1083 }
1085 // Returns true if the AliasType refers to the value field of an
1086 // autobox object. Currently only handles Integer.
1087 static bool is_autobox_object(Compile::AliasType* atp) {
1088 if (atp != NULL && atp->field() != NULL) {
1089 ciField* field = atp->field();
1090 ciSymbol* klass = field->holder()->name();
1091 if (field->name() == ciSymbol::value_name() &&
1092 field->holder()->uses_default_loader() &&
1093 klass == ciSymbol::java_lang_Integer()) {
1094 return true;
1095 }
1096 }
1097 return false;
1098 }
1101 // We're loading from an object which has autobox behaviour.
1102 // If this object is result of a valueOf call we'll have a phi
1103 // merging a newly allocated object and a load from the cache.
1104 // We want to replace this load with the original incoming
1105 // argument to the valueOf call.
1106 Node* LoadNode::eliminate_autobox(PhaseGVN* phase) {
1107 Node* base = in(Address)->in(AddPNode::Base);
1108 if (base->is_Phi() && base->req() == 3) {
1109 AllocateNode* allocation = NULL;
1110 int allocation_index = -1;
1111 int load_index = -1;
1112 for (uint i = 1; i < base->req(); i++) {
1113 allocation = AllocateNode::Ideal_allocation(base->in(i), phase);
1114 if (allocation != NULL) {
1115 allocation_index = i;
1116 load_index = 3 - allocation_index;
1117 break;
1118 }
1119 }
1120 bool has_load = ( allocation != NULL &&
1121 (base->in(load_index)->is_Load() ||
1122 base->in(load_index)->is_DecodeN() &&
1123 base->in(load_index)->in(1)->is_Load()) );
1124 if (has_load && in(Memory)->is_Phi() && in(Memory)->in(0) == base->in(0)) {
1125 // Push the loads from the phi that comes from valueOf up
1126 // through it to allow elimination of the loads and the recovery
1127 // of the original value.
1128 Node* mem_phi = in(Memory);
1129 Node* offset = in(Address)->in(AddPNode::Offset);
1130 Node* region = base->in(0);
1132 Node* in1 = clone();
1133 Node* in1_addr = in1->in(Address)->clone();
1134 in1_addr->set_req(AddPNode::Base, base->in(allocation_index));
1135 in1_addr->set_req(AddPNode::Address, base->in(allocation_index));
1136 in1_addr->set_req(AddPNode::Offset, offset);
1137 in1->set_req(0, region->in(allocation_index));
1138 in1->set_req(Address, in1_addr);
1139 in1->set_req(Memory, mem_phi->in(allocation_index));
1141 Node* in2 = clone();
1142 Node* in2_addr = in2->in(Address)->clone();
1143 in2_addr->set_req(AddPNode::Base, base->in(load_index));
1144 in2_addr->set_req(AddPNode::Address, base->in(load_index));
1145 in2_addr->set_req(AddPNode::Offset, offset);
1146 in2->set_req(0, region->in(load_index));
1147 in2->set_req(Address, in2_addr);
1148 in2->set_req(Memory, mem_phi->in(load_index));
1150 in1_addr = phase->transform(in1_addr);
1151 in1 = phase->transform(in1);
1152 in2_addr = phase->transform(in2_addr);
1153 in2 = phase->transform(in2);
1155 PhiNode* result = PhiNode::make_blank(region, this);
1156 result->set_req(allocation_index, in1);
1157 result->set_req(load_index, in2);
1158 return result;
1159 }
1160 } else if (base->is_Load() ||
1161 base->is_DecodeN() && base->in(1)->is_Load()) {
1162 if (base->is_DecodeN()) {
1163 // Get LoadN node which loads cached Integer object
1164 base = base->in(1);
1165 }
1166 // Eliminate the load of Integer.value for integers from the cache
1167 // array by deriving the value from the index into the array.
1168 // Capture the offset of the load and then reverse the computation.
1169 Node* load_base = base->in(Address)->in(AddPNode::Base);
1170 if (load_base->is_DecodeN()) {
1171 // Get LoadN node which loads IntegerCache.cache field
1172 load_base = load_base->in(1);
1173 }
1174 if (load_base != NULL) {
1175 Compile::AliasType* atp = phase->C->alias_type(load_base->adr_type());
1176 intptr_t cache_offset;
1177 int shift = -1;
1178 Node* cache = NULL;
1179 if (is_autobox_cache(atp)) {
1180 shift = exact_log2(type2aelembytes(T_OBJECT));
1181 cache = AddPNode::Ideal_base_and_offset(load_base->in(Address), phase, cache_offset);
1182 }
1183 if (cache != NULL && base->in(Address)->is_AddP()) {
1184 Node* elements[4];
1185 int count = base->in(Address)->as_AddP()->unpack_offsets(elements, ARRAY_SIZE(elements));
1186 int cache_low;
1187 if (count > 0 && fetch_autobox_base(atp, cache_low)) {
1188 int offset = arrayOopDesc::base_offset_in_bytes(memory_type()) - (cache_low << shift);
1189 // Add up all the offsets making of the address of the load
1190 Node* result = elements[0];
1191 for (int i = 1; i < count; i++) {
1192 result = phase->transform(new (phase->C, 3) AddXNode(result, elements[i]));
1193 }
1194 // Remove the constant offset from the address and then
1195 // remove the scaling of the offset to recover the original index.
1196 result = phase->transform(new (phase->C, 3) AddXNode(result, phase->MakeConX(-offset)));
1197 if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) {
1198 // Peel the shift off directly but wrap it in a dummy node
1199 // since Ideal can't return existing nodes
1200 result = new (phase->C, 3) RShiftXNode(result->in(1), phase->intcon(0));
1201 } else {
1202 result = new (phase->C, 3) RShiftXNode(result, phase->intcon(shift));
1203 }
1204 #ifdef _LP64
1205 result = new (phase->C, 2) ConvL2INode(phase->transform(result));
1206 #endif
1207 return result;
1208 }
1209 }
1210 }
1211 }
1212 return NULL;
1213 }
1215 //------------------------------split_through_phi------------------------------
1216 // Split instance field load through Phi.
1217 Node *LoadNode::split_through_phi(PhaseGVN *phase) {
1218 Node* mem = in(MemNode::Memory);
1219 Node* address = in(MemNode::Address);
1220 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1221 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1223 assert(mem->is_Phi() && (t_oop != NULL) &&
1224 t_oop->is_known_instance_field(), "invalide conditions");
1226 Node *region = mem->in(0);
1227 if (region == NULL) {
1228 return NULL; // Wait stable graph
1229 }
1230 uint cnt = mem->req();
1231 for( uint i = 1; i < cnt; i++ ) {
1232 Node *in = mem->in(i);
1233 if( in == NULL ) {
1234 return NULL; // Wait stable graph
1235 }
1236 }
1237 // Check for loop invariant.
1238 if (cnt == 3) {
1239 for( uint i = 1; i < cnt; i++ ) {
1240 Node *in = mem->in(i);
1241 Node* m = MemNode::optimize_memory_chain(in, addr_t, phase);
1242 if (m == mem) {
1243 set_req(MemNode::Memory, mem->in(cnt - i)); // Skip this phi.
1244 return this;
1245 }
1246 }
1247 }
1248 // Split through Phi (see original code in loopopts.cpp).
1249 assert(phase->C->have_alias_type(addr_t), "instance should have alias type");
1251 // Do nothing here if Identity will find a value
1252 // (to avoid infinite chain of value phis generation).
1253 if ( !phase->eqv(this, this->Identity(phase)) )
1254 return NULL;
1256 // Skip the split if the region dominates some control edge of the address.
1257 if (cnt == 3 && !MemNode::all_controls_dominate(address, region))
1258 return NULL;
1260 const Type* this_type = this->bottom_type();
1261 int this_index = phase->C->get_alias_index(addr_t);
1262 int this_offset = addr_t->offset();
1263 int this_iid = addr_t->is_oopptr()->instance_id();
1264 int wins = 0;
1265 PhaseIterGVN *igvn = phase->is_IterGVN();
1266 Node *phi = new (igvn->C, region->req()) PhiNode(region, this_type, NULL, this_iid, this_index, this_offset);
1267 for( uint i = 1; i < region->req(); i++ ) {
1268 Node *x;
1269 Node* the_clone = NULL;
1270 if( region->in(i) == phase->C->top() ) {
1271 x = phase->C->top(); // Dead path? Use a dead data op
1272 } else {
1273 x = this->clone(); // Else clone up the data op
1274 the_clone = x; // Remember for possible deletion.
1275 // Alter data node to use pre-phi inputs
1276 if( this->in(0) == region ) {
1277 x->set_req( 0, region->in(i) );
1278 } else {
1279 x->set_req( 0, NULL );
1280 }
1281 for( uint j = 1; j < this->req(); j++ ) {
1282 Node *in = this->in(j);
1283 if( in->is_Phi() && in->in(0) == region )
1284 x->set_req( j, in->in(i) ); // Use pre-Phi input for the clone
1285 }
1286 }
1287 // Check for a 'win' on some paths
1288 const Type *t = x->Value(igvn);
1290 bool singleton = t->singleton();
1292 // See comments in PhaseIdealLoop::split_thru_phi().
1293 if( singleton && t == Type::TOP ) {
1294 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1295 }
1297 if( singleton ) {
1298 wins++;
1299 x = igvn->makecon(t);
1300 } else {
1301 // We now call Identity to try to simplify the cloned node.
1302 // Note that some Identity methods call phase->type(this).
1303 // Make sure that the type array is big enough for
1304 // our new node, even though we may throw the node away.
1305 // (This tweaking with igvn only works because x is a new node.)
1306 igvn->set_type(x, t);
1307 // If x is a TypeNode, capture any more-precise type permanently into Node
1308 // otherwise it will be not updated during igvn->transform since
1309 // igvn->type(x) is set to x->Value() already.
1310 x->raise_bottom_type(t);
1311 Node *y = x->Identity(igvn);
1312 if( y != x ) {
1313 wins++;
1314 x = y;
1315 } else {
1316 y = igvn->hash_find(x);
1317 if( y ) {
1318 wins++;
1319 x = y;
1320 } else {
1321 // Else x is a new node we are keeping
1322 // We do not need register_new_node_with_optimizer
1323 // because set_type has already been called.
1324 igvn->_worklist.push(x);
1325 }
1326 }
1327 }
1328 if (x != the_clone && the_clone != NULL)
1329 igvn->remove_dead_node(the_clone);
1330 phi->set_req(i, x);
1331 }
1332 if( wins > 0 ) {
1333 // Record Phi
1334 igvn->register_new_node_with_optimizer(phi);
1335 return phi;
1336 }
1337 igvn->remove_dead_node(phi);
1338 return NULL;
1339 }
1341 //------------------------------Ideal------------------------------------------
1342 // If the load is from Field memory and the pointer is non-null, we can
1343 // zero out the control input.
1344 // If the offset is constant and the base is an object allocation,
1345 // try to hook me up to the exact initializing store.
1346 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1347 Node* p = MemNode::Ideal_common(phase, can_reshape);
1348 if (p) return (p == NodeSentinel) ? NULL : p;
1350 Node* ctrl = in(MemNode::Control);
1351 Node* address = in(MemNode::Address);
1353 // Skip up past a SafePoint control. Cannot do this for Stores because
1354 // pointer stores & cardmarks must stay on the same side of a SafePoint.
1355 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint &&
1356 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw ) {
1357 ctrl = ctrl->in(0);
1358 set_req(MemNode::Control,ctrl);
1359 }
1361 intptr_t ignore = 0;
1362 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1363 if (base != NULL
1364 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
1365 // Check for useless control edge in some common special cases
1366 if (in(MemNode::Control) != NULL
1367 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1368 && all_controls_dominate(base, phase->C->start())) {
1369 // A method-invariant, non-null address (constant or 'this' argument).
1370 set_req(MemNode::Control, NULL);
1371 }
1373 if (EliminateAutoBox && can_reshape) {
1374 assert(!phase->type(base)->higher_equal(TypePtr::NULL_PTR), "the autobox pointer should be non-null");
1375 Compile::AliasType* atp = phase->C->alias_type(adr_type());
1376 if (is_autobox_object(atp)) {
1377 Node* result = eliminate_autobox(phase);
1378 if (result != NULL) return result;
1379 }
1380 }
1381 }
1383 Node* mem = in(MemNode::Memory);
1384 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1386 if (addr_t != NULL) {
1387 // try to optimize our memory input
1388 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, phase);
1389 if (opt_mem != mem) {
1390 set_req(MemNode::Memory, opt_mem);
1391 if (phase->type( opt_mem ) == Type::TOP) return NULL;
1392 return this;
1393 }
1394 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1395 if (can_reshape && opt_mem->is_Phi() &&
1396 (t_oop != NULL) && t_oop->is_known_instance_field()) {
1397 // Split instance field load through Phi.
1398 Node* result = split_through_phi(phase);
1399 if (result != NULL) return result;
1400 }
1401 }
1403 // Check for prior store with a different base or offset; make Load
1404 // independent. Skip through any number of them. Bail out if the stores
1405 // are in an endless dead cycle and report no progress. This is a key
1406 // transform for Reflection. However, if after skipping through the Stores
1407 // we can't then fold up against a prior store do NOT do the transform as
1408 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
1409 // array memory alive twice: once for the hoisted Load and again after the
1410 // bypassed Store. This situation only works if EVERYBODY who does
1411 // anti-dependence work knows how to bypass. I.e. we need all
1412 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
1413 // the alias index stuff. So instead, peek through Stores and IFF we can
1414 // fold up, do so.
1415 Node* prev_mem = find_previous_store(phase);
1416 // Steps (a), (b): Walk past independent stores to find an exact match.
1417 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) {
1418 // (c) See if we can fold up on the spot, but don't fold up here.
1419 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
1420 // just return a prior value, which is done by Identity calls.
1421 if (can_see_stored_value(prev_mem, phase)) {
1422 // Make ready for step (d):
1423 set_req(MemNode::Memory, prev_mem);
1424 return this;
1425 }
1426 }
1428 return NULL; // No further progress
1429 }
1431 // Helper to recognize certain Klass fields which are invariant across
1432 // some group of array types (e.g., int[] or all T[] where T < Object).
1433 const Type*
1434 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1435 ciKlass* klass) const {
1436 if (tkls->offset() == Klass::modifier_flags_offset_in_bytes() + (int)sizeof(oopDesc)) {
1437 // The field is Klass::_modifier_flags. Return its (constant) value.
1438 // (Folds up the 2nd indirection in aClassConstant.getModifiers().)
1439 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags");
1440 return TypeInt::make(klass->modifier_flags());
1441 }
1442 if (tkls->offset() == Klass::access_flags_offset_in_bytes() + (int)sizeof(oopDesc)) {
1443 // The field is Klass::_access_flags. Return its (constant) value.
1444 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1445 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags");
1446 return TypeInt::make(klass->access_flags());
1447 }
1448 if (tkls->offset() == Klass::layout_helper_offset_in_bytes() + (int)sizeof(oopDesc)) {
1449 // The field is Klass::_layout_helper. Return its constant value if known.
1450 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper");
1451 return TypeInt::make(klass->layout_helper());
1452 }
1454 // No match.
1455 return NULL;
1456 }
1458 //------------------------------Value-----------------------------------------
1459 const Type *LoadNode::Value( PhaseTransform *phase ) const {
1460 // Either input is TOP ==> the result is TOP
1461 Node* mem = in(MemNode::Memory);
1462 const Type *t1 = phase->type(mem);
1463 if (t1 == Type::TOP) return Type::TOP;
1464 Node* adr = in(MemNode::Address);
1465 const TypePtr* tp = phase->type(adr)->isa_ptr();
1466 if (tp == NULL || tp->empty()) return Type::TOP;
1467 int off = tp->offset();
1468 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
1470 // Try to guess loaded type from pointer type
1471 if (tp->base() == Type::AryPtr) {
1472 const Type *t = tp->is_aryptr()->elem();
1473 // Don't do this for integer types. There is only potential profit if
1474 // the element type t is lower than _type; that is, for int types, if _type is
1475 // more restrictive than t. This only happens here if one is short and the other
1476 // char (both 16 bits), and in those cases we've made an intentional decision
1477 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
1478 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
1479 //
1480 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
1481 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
1482 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
1483 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
1484 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
1485 // In fact, that could have been the original type of p1, and p1 could have
1486 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
1487 // expression (LShiftL quux 3) independently optimized to the constant 8.
1488 if ((t->isa_int() == NULL) && (t->isa_long() == NULL)
1489 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
1490 // t might actually be lower than _type, if _type is a unique
1491 // concrete subclass of abstract class t.
1492 // Make sure the reference is not into the header, by comparing
1493 // the offset against the offset of the start of the array's data.
1494 // Different array types begin at slightly different offsets (12 vs. 16).
1495 // We choose T_BYTE as an example base type that is least restrictive
1496 // as to alignment, which will therefore produce the smallest
1497 // possible base offset.
1498 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
1499 if ((uint)off >= (uint)min_base_off) { // is the offset beyond the header?
1500 const Type* jt = t->join(_type);
1501 // In any case, do not allow the join, per se, to empty out the type.
1502 if (jt->empty() && !t->empty()) {
1503 // This can happen if a interface-typed array narrows to a class type.
1504 jt = _type;
1505 }
1507 if (EliminateAutoBox && adr->is_AddP()) {
1508 // The pointers in the autobox arrays are always non-null
1509 Node* base = adr->in(AddPNode::Base);
1510 if (base != NULL &&
1511 !phase->type(base)->higher_equal(TypePtr::NULL_PTR)) {
1512 Compile::AliasType* atp = phase->C->alias_type(base->adr_type());
1513 if (is_autobox_cache(atp)) {
1514 return jt->join(TypePtr::NOTNULL)->is_ptr();
1515 }
1516 }
1517 }
1518 return jt;
1519 }
1520 }
1521 } else if (tp->base() == Type::InstPtr) {
1522 const TypeInstPtr* tinst = tp->is_instptr();
1523 ciKlass* klass = tinst->klass();
1524 assert( off != Type::OffsetBot ||
1525 // arrays can be cast to Objects
1526 tp->is_oopptr()->klass()->is_java_lang_Object() ||
1527 // unsafe field access may not have a constant offset
1528 phase->C->has_unsafe_access(),
1529 "Field accesses must be precise" );
1530 // For oop loads, we expect the _type to be precise
1531 if (OptimizeStringConcat && klass == phase->C->env()->String_klass() &&
1532 adr->is_AddP() && off != Type::OffsetBot) {
1533 // For constant Strings treat the fields as compile time constants.
1534 Node* base = adr->in(AddPNode::Base);
1535 if (base->Opcode() == Op_ConP) {
1536 const TypeOopPtr* t = phase->type(base)->isa_oopptr();
1537 ciObject* string = t->const_oop();
1538 ciConstant constant = string->as_instance()->field_value_by_offset(off);
1539 if (constant.basic_type() == T_INT) {
1540 return TypeInt::make(constant.as_int());
1541 } else if (constant.basic_type() == T_ARRAY) {
1542 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
1543 return TypeNarrowOop::make_from_constant(constant.as_object());
1544 } else {
1545 return TypeOopPtr::make_from_constant(constant.as_object());
1546 }
1547 }
1548 }
1549 }
1550 } else if (tp->base() == Type::KlassPtr) {
1551 assert( off != Type::OffsetBot ||
1552 // arrays can be cast to Objects
1553 tp->is_klassptr()->klass()->is_java_lang_Object() ||
1554 // also allow array-loading from the primary supertype
1555 // array during subtype checks
1556 Opcode() == Op_LoadKlass,
1557 "Field accesses must be precise" );
1558 // For klass/static loads, we expect the _type to be precise
1559 }
1561 const TypeKlassPtr *tkls = tp->isa_klassptr();
1562 if (tkls != NULL && !StressReflectiveCode) {
1563 ciKlass* klass = tkls->klass();
1564 if (klass->is_loaded() && tkls->klass_is_exact()) {
1565 // We are loading a field from a Klass metaobject whose identity
1566 // is known at compile time (the type is "exact" or "precise").
1567 // Check for fields we know are maintained as constants by the VM.
1568 if (tkls->offset() == Klass::super_check_offset_offset_in_bytes() + (int)sizeof(oopDesc)) {
1569 // The field is Klass::_super_check_offset. Return its (constant) value.
1570 // (Folds up type checking code.)
1571 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
1572 return TypeInt::make(klass->super_check_offset());
1573 }
1574 // Compute index into primary_supers array
1575 juint depth = (tkls->offset() - (Klass::primary_supers_offset_in_bytes() + (int)sizeof(oopDesc))) / sizeof(klassOop);
1576 // Check for overflowing; use unsigned compare to handle the negative case.
1577 if( depth < ciKlass::primary_super_limit() ) {
1578 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1579 // (Folds up type checking code.)
1580 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1581 ciKlass *ss = klass->super_of_depth(depth);
1582 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1583 }
1584 const Type* aift = load_array_final_field(tkls, klass);
1585 if (aift != NULL) return aift;
1586 if (tkls->offset() == in_bytes(arrayKlass::component_mirror_offset()) + (int)sizeof(oopDesc)
1587 && klass->is_array_klass()) {
1588 // The field is arrayKlass::_component_mirror. Return its (constant) value.
1589 // (Folds up aClassConstant.getComponentType, common in Arrays.copyOf.)
1590 assert(Opcode() == Op_LoadP, "must load an oop from _component_mirror");
1591 return TypeInstPtr::make(klass->as_array_klass()->component_mirror());
1592 }
1593 if (tkls->offset() == Klass::java_mirror_offset_in_bytes() + (int)sizeof(oopDesc)) {
1594 // The field is Klass::_java_mirror. Return its (constant) value.
1595 // (Folds up the 2nd indirection in anObjConstant.getClass().)
1596 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
1597 return TypeInstPtr::make(klass->java_mirror());
1598 }
1599 }
1601 // We can still check if we are loading from the primary_supers array at a
1602 // shallow enough depth. Even though the klass is not exact, entries less
1603 // than or equal to its super depth are correct.
1604 if (klass->is_loaded() ) {
1605 ciType *inner = klass->klass();
1606 while( inner->is_obj_array_klass() )
1607 inner = inner->as_obj_array_klass()->base_element_type();
1608 if( inner->is_instance_klass() &&
1609 !inner->as_instance_klass()->flags().is_interface() ) {
1610 // Compute index into primary_supers array
1611 juint depth = (tkls->offset() - (Klass::primary_supers_offset_in_bytes() + (int)sizeof(oopDesc))) / sizeof(klassOop);
1612 // Check for overflowing; use unsigned compare to handle the negative case.
1613 if( depth < ciKlass::primary_super_limit() &&
1614 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case
1615 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1616 // (Folds up type checking code.)
1617 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1618 ciKlass *ss = klass->super_of_depth(depth);
1619 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1620 }
1621 }
1622 }
1624 // If the type is enough to determine that the thing is not an array,
1625 // we can give the layout_helper a positive interval type.
1626 // This will help short-circuit some reflective code.
1627 if (tkls->offset() == Klass::layout_helper_offset_in_bytes() + (int)sizeof(oopDesc)
1628 && !klass->is_array_klass() // not directly typed as an array
1629 && !klass->is_interface() // specifically not Serializable & Cloneable
1630 && !klass->is_java_lang_Object() // not the supertype of all T[]
1631 ) {
1632 // Note: When interfaces are reliable, we can narrow the interface
1633 // test to (klass != Serializable && klass != Cloneable).
1634 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
1635 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
1636 // The key property of this type is that it folds up tests
1637 // for array-ness, since it proves that the layout_helper is positive.
1638 // Thus, a generic value like the basic object layout helper works fine.
1639 return TypeInt::make(min_size, max_jint, Type::WidenMin);
1640 }
1641 }
1643 // If we are loading from a freshly-allocated object, produce a zero,
1644 // if the load is provably beyond the header of the object.
1645 // (Also allow a variable load from a fresh array to produce zero.)
1646 if (ReduceFieldZeroing) {
1647 Node* value = can_see_stored_value(mem,phase);
1648 if (value != NULL && value->is_Con())
1649 return value->bottom_type();
1650 }
1652 const TypeOopPtr *tinst = tp->isa_oopptr();
1653 if (tinst != NULL && tinst->is_known_instance_field()) {
1654 // If we have an instance type and our memory input is the
1655 // programs's initial memory state, there is no matching store,
1656 // so just return a zero of the appropriate type
1657 Node *mem = in(MemNode::Memory);
1658 if (mem->is_Parm() && mem->in(0)->is_Start()) {
1659 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
1660 return Type::get_zero_type(_type->basic_type());
1661 }
1662 }
1663 return _type;
1664 }
1666 //------------------------------match_edge-------------------------------------
1667 // Do we Match on this edge index or not? Match only the address.
1668 uint LoadNode::match_edge(uint idx) const {
1669 return idx == MemNode::Address;
1670 }
1672 //--------------------------LoadBNode::Ideal--------------------------------------
1673 //
1674 // If the previous store is to the same address as this load,
1675 // and the value stored was larger than a byte, replace this load
1676 // with the value stored truncated to a byte. If no truncation is
1677 // needed, the replacement is done in LoadNode::Identity().
1678 //
1679 Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1680 Node* mem = in(MemNode::Memory);
1681 Node* value = can_see_stored_value(mem,phase);
1682 if( value && !phase->type(value)->higher_equal( _type ) ) {
1683 Node *result = phase->transform( new (phase->C, 3) LShiftINode(value, phase->intcon(24)) );
1684 return new (phase->C, 3) RShiftINode(result, phase->intcon(24));
1685 }
1686 // Identity call will handle the case where truncation is not needed.
1687 return LoadNode::Ideal(phase, can_reshape);
1688 }
1690 //--------------------------LoadUBNode::Ideal-------------------------------------
1691 //
1692 // If the previous store is to the same address as this load,
1693 // and the value stored was larger than a byte, replace this load
1694 // with the value stored truncated to a byte. If no truncation is
1695 // needed, the replacement is done in LoadNode::Identity().
1696 //
1697 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
1698 Node* mem = in(MemNode::Memory);
1699 Node* value = can_see_stored_value(mem, phase);
1700 if (value && !phase->type(value)->higher_equal(_type))
1701 return new (phase->C, 3) AndINode(value, phase->intcon(0xFF));
1702 // Identity call will handle the case where truncation is not needed.
1703 return LoadNode::Ideal(phase, can_reshape);
1704 }
1706 //--------------------------LoadUSNode::Ideal-------------------------------------
1707 //
1708 // If the previous store is to the same address as this load,
1709 // and the value stored was larger than a char, replace this load
1710 // with the value stored truncated to a char. If no truncation is
1711 // needed, the replacement is done in LoadNode::Identity().
1712 //
1713 Node *LoadUSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1714 Node* mem = in(MemNode::Memory);
1715 Node* value = can_see_stored_value(mem,phase);
1716 if( value && !phase->type(value)->higher_equal( _type ) )
1717 return new (phase->C, 3) AndINode(value,phase->intcon(0xFFFF));
1718 // Identity call will handle the case where truncation is not needed.
1719 return LoadNode::Ideal(phase, can_reshape);
1720 }
1722 //--------------------------LoadSNode::Ideal--------------------------------------
1723 //
1724 // If the previous store is to the same address as this load,
1725 // and the value stored was larger than a short, replace this load
1726 // with the value stored truncated to a short. If no truncation is
1727 // needed, the replacement is done in LoadNode::Identity().
1728 //
1729 Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1730 Node* mem = in(MemNode::Memory);
1731 Node* value = can_see_stored_value(mem,phase);
1732 if( value && !phase->type(value)->higher_equal( _type ) ) {
1733 Node *result = phase->transform( new (phase->C, 3) LShiftINode(value, phase->intcon(16)) );
1734 return new (phase->C, 3) RShiftINode(result, phase->intcon(16));
1735 }
1736 // Identity call will handle the case where truncation is not needed.
1737 return LoadNode::Ideal(phase, can_reshape);
1738 }
1740 //=============================================================================
1741 //----------------------------LoadKlassNode::make------------------------------
1742 // Polymorphic factory method:
1743 Node *LoadKlassNode::make( PhaseGVN& gvn, Node *mem, Node *adr, const TypePtr* at, const TypeKlassPtr *tk ) {
1744 Compile* C = gvn.C;
1745 Node *ctl = NULL;
1746 // sanity check the alias category against the created node type
1747 const TypeOopPtr *adr_type = adr->bottom_type()->isa_oopptr();
1748 assert(adr_type != NULL, "expecting TypeOopPtr");
1749 #ifdef _LP64
1750 if (adr_type->is_ptr_to_narrowoop()) {
1751 Node* load_klass = gvn.transform(new (C, 3) LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowoop()));
1752 return new (C, 2) DecodeNNode(load_klass, load_klass->bottom_type()->make_ptr());
1753 }
1754 #endif
1755 assert(!adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
1756 return new (C, 3) LoadKlassNode(ctl, mem, adr, at, tk);
1757 }
1759 //------------------------------Value------------------------------------------
1760 const Type *LoadKlassNode::Value( PhaseTransform *phase ) const {
1761 return klass_value_common(phase);
1762 }
1764 const Type *LoadNode::klass_value_common( PhaseTransform *phase ) const {
1765 // Either input is TOP ==> the result is TOP
1766 const Type *t1 = phase->type( in(MemNode::Memory) );
1767 if (t1 == Type::TOP) return Type::TOP;
1768 Node *adr = in(MemNode::Address);
1769 const Type *t2 = phase->type( adr );
1770 if (t2 == Type::TOP) return Type::TOP;
1771 const TypePtr *tp = t2->is_ptr();
1772 if (TypePtr::above_centerline(tp->ptr()) ||
1773 tp->ptr() == TypePtr::Null) return Type::TOP;
1775 // Return a more precise klass, if possible
1776 const TypeInstPtr *tinst = tp->isa_instptr();
1777 if (tinst != NULL) {
1778 ciInstanceKlass* ik = tinst->klass()->as_instance_klass();
1779 int offset = tinst->offset();
1780 if (ik == phase->C->env()->Class_klass()
1781 && (offset == java_lang_Class::klass_offset_in_bytes() ||
1782 offset == java_lang_Class::array_klass_offset_in_bytes())) {
1783 // We are loading a special hidden field from a Class mirror object,
1784 // the field which points to the VM's Klass metaobject.
1785 ciType* t = tinst->java_mirror_type();
1786 // java_mirror_type returns non-null for compile-time Class constants.
1787 if (t != NULL) {
1788 // constant oop => constant klass
1789 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
1790 return TypeKlassPtr::make(ciArrayKlass::make(t));
1791 }
1792 if (!t->is_klass()) {
1793 // a primitive Class (e.g., int.class) has NULL for a klass field
1794 return TypePtr::NULL_PTR;
1795 }
1796 // (Folds up the 1st indirection in aClassConstant.getModifiers().)
1797 return TypeKlassPtr::make(t->as_klass());
1798 }
1799 // non-constant mirror, so we can't tell what's going on
1800 }
1801 if( !ik->is_loaded() )
1802 return _type; // Bail out if not loaded
1803 if (offset == oopDesc::klass_offset_in_bytes()) {
1804 if (tinst->klass_is_exact()) {
1805 return TypeKlassPtr::make(ik);
1806 }
1807 // See if we can become precise: no subklasses and no interface
1808 // (Note: We need to support verified interfaces.)
1809 if (!ik->is_interface() && !ik->has_subklass()) {
1810 //assert(!UseExactTypes, "this code should be useless with exact types");
1811 // Add a dependence; if any subclass added we need to recompile
1812 if (!ik->is_final()) {
1813 // %%% should use stronger assert_unique_concrete_subtype instead
1814 phase->C->dependencies()->assert_leaf_type(ik);
1815 }
1816 // Return precise klass
1817 return TypeKlassPtr::make(ik);
1818 }
1820 // Return root of possible klass
1821 return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/);
1822 }
1823 }
1825 // Check for loading klass from an array
1826 const TypeAryPtr *tary = tp->isa_aryptr();
1827 if( tary != NULL ) {
1828 ciKlass *tary_klass = tary->klass();
1829 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP
1830 && tary->offset() == oopDesc::klass_offset_in_bytes()) {
1831 if (tary->klass_is_exact()) {
1832 return TypeKlassPtr::make(tary_klass);
1833 }
1834 ciArrayKlass *ak = tary->klass()->as_array_klass();
1835 // If the klass is an object array, we defer the question to the
1836 // array component klass.
1837 if( ak->is_obj_array_klass() ) {
1838 assert( ak->is_loaded(), "" );
1839 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass();
1840 if( base_k->is_loaded() && base_k->is_instance_klass() ) {
1841 ciInstanceKlass* ik = base_k->as_instance_klass();
1842 // See if we can become precise: no subklasses and no interface
1843 if (!ik->is_interface() && !ik->has_subklass()) {
1844 //assert(!UseExactTypes, "this code should be useless with exact types");
1845 // Add a dependence; if any subclass added we need to recompile
1846 if (!ik->is_final()) {
1847 phase->C->dependencies()->assert_leaf_type(ik);
1848 }
1849 // Return precise array klass
1850 return TypeKlassPtr::make(ak);
1851 }
1852 }
1853 return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/);
1854 } else { // Found a type-array?
1855 //assert(!UseExactTypes, "this code should be useless with exact types");
1856 assert( ak->is_type_array_klass(), "" );
1857 return TypeKlassPtr::make(ak); // These are always precise
1858 }
1859 }
1860 }
1862 // Check for loading klass from an array klass
1863 const TypeKlassPtr *tkls = tp->isa_klassptr();
1864 if (tkls != NULL && !StressReflectiveCode) {
1865 ciKlass* klass = tkls->klass();
1866 if( !klass->is_loaded() )
1867 return _type; // Bail out if not loaded
1868 if( klass->is_obj_array_klass() &&
1869 (uint)tkls->offset() == objArrayKlass::element_klass_offset_in_bytes() + sizeof(oopDesc)) {
1870 ciKlass* elem = klass->as_obj_array_klass()->element_klass();
1871 // // Always returning precise element type is incorrect,
1872 // // e.g., element type could be object and array may contain strings
1873 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
1875 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
1876 // according to the element type's subclassing.
1877 return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/);
1878 }
1879 if( klass->is_instance_klass() && tkls->klass_is_exact() &&
1880 (uint)tkls->offset() == Klass::super_offset_in_bytes() + sizeof(oopDesc)) {
1881 ciKlass* sup = klass->as_instance_klass()->super();
1882 // The field is Klass::_super. Return its (constant) value.
1883 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
1884 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR;
1885 }
1886 }
1888 // Bailout case
1889 return LoadNode::Value(phase);
1890 }
1892 //------------------------------Identity---------------------------------------
1893 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
1894 // Also feed through the klass in Allocate(...klass...)._klass.
1895 Node* LoadKlassNode::Identity( PhaseTransform *phase ) {
1896 return klass_identity_common(phase);
1897 }
1899 Node* LoadNode::klass_identity_common(PhaseTransform *phase ) {
1900 Node* x = LoadNode::Identity(phase);
1901 if (x != this) return x;
1903 // Take apart the address into an oop and and offset.
1904 // Return 'this' if we cannot.
1905 Node* adr = in(MemNode::Address);
1906 intptr_t offset = 0;
1907 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
1908 if (base == NULL) return this;
1909 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
1910 if (toop == NULL) return this;
1912 // We can fetch the klass directly through an AllocateNode.
1913 // This works even if the klass is not constant (clone or newArray).
1914 if (offset == oopDesc::klass_offset_in_bytes()) {
1915 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
1916 if (allocated_klass != NULL) {
1917 return allocated_klass;
1918 }
1919 }
1921 // Simplify k.java_mirror.as_klass to plain k, where k is a klassOop.
1922 // Simplify ak.component_mirror.array_klass to plain ak, ak an arrayKlass.
1923 // See inline_native_Class_query for occurrences of these patterns.
1924 // Java Example: x.getClass().isAssignableFrom(y)
1925 // Java Example: Array.newInstance(x.getClass().getComponentType(), n)
1926 //
1927 // This improves reflective code, often making the Class
1928 // mirror go completely dead. (Current exception: Class
1929 // mirrors may appear in debug info, but we could clean them out by
1930 // introducing a new debug info operator for klassOop.java_mirror).
1931 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass()
1932 && (offset == java_lang_Class::klass_offset_in_bytes() ||
1933 offset == java_lang_Class::array_klass_offset_in_bytes())) {
1934 // We are loading a special hidden field from a Class mirror,
1935 // the field which points to its Klass or arrayKlass metaobject.
1936 if (base->is_Load()) {
1937 Node* adr2 = base->in(MemNode::Address);
1938 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
1939 if (tkls != NULL && !tkls->empty()
1940 && (tkls->klass()->is_instance_klass() ||
1941 tkls->klass()->is_array_klass())
1942 && adr2->is_AddP()
1943 ) {
1944 int mirror_field = Klass::java_mirror_offset_in_bytes();
1945 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
1946 mirror_field = in_bytes(arrayKlass::component_mirror_offset());
1947 }
1948 if (tkls->offset() == mirror_field + (int)sizeof(oopDesc)) {
1949 return adr2->in(AddPNode::Base);
1950 }
1951 }
1952 }
1953 }
1955 return this;
1956 }
1959 //------------------------------Value------------------------------------------
1960 const Type *LoadNKlassNode::Value( PhaseTransform *phase ) const {
1961 const Type *t = klass_value_common(phase);
1962 if (t == Type::TOP)
1963 return t;
1965 return t->make_narrowoop();
1966 }
1968 //------------------------------Identity---------------------------------------
1969 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
1970 // Also feed through the klass in Allocate(...klass...)._klass.
1971 Node* LoadNKlassNode::Identity( PhaseTransform *phase ) {
1972 Node *x = klass_identity_common(phase);
1974 const Type *t = phase->type( x );
1975 if( t == Type::TOP ) return x;
1976 if( t->isa_narrowoop()) return x;
1978 return phase->transform(new (phase->C, 2) EncodePNode(x, t->make_narrowoop()));
1979 }
1981 //------------------------------Value-----------------------------------------
1982 const Type *LoadRangeNode::Value( PhaseTransform *phase ) const {
1983 // Either input is TOP ==> the result is TOP
1984 const Type *t1 = phase->type( in(MemNode::Memory) );
1985 if( t1 == Type::TOP ) return Type::TOP;
1986 Node *adr = in(MemNode::Address);
1987 const Type *t2 = phase->type( adr );
1988 if( t2 == Type::TOP ) return Type::TOP;
1989 const TypePtr *tp = t2->is_ptr();
1990 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
1991 const TypeAryPtr *tap = tp->isa_aryptr();
1992 if( !tap ) return _type;
1993 return tap->size();
1994 }
1996 //-------------------------------Ideal---------------------------------------
1997 // Feed through the length in AllocateArray(...length...)._length.
1998 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1999 Node* p = MemNode::Ideal_common(phase, can_reshape);
2000 if (p) return (p == NodeSentinel) ? NULL : p;
2002 // Take apart the address into an oop and and offset.
2003 // Return 'this' if we cannot.
2004 Node* adr = in(MemNode::Address);
2005 intptr_t offset = 0;
2006 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2007 if (base == NULL) return NULL;
2008 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2009 if (tary == NULL) return NULL;
2011 // We can fetch the length directly through an AllocateArrayNode.
2012 // This works even if the length is not constant (clone or newArray).
2013 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2014 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2015 if (alloc != NULL) {
2016 Node* allocated_length = alloc->Ideal_length();
2017 Node* len = alloc->make_ideal_length(tary, phase);
2018 if (allocated_length != len) {
2019 // New CastII improves on this.
2020 return len;
2021 }
2022 }
2023 }
2025 return NULL;
2026 }
2028 //------------------------------Identity---------------------------------------
2029 // Feed through the length in AllocateArray(...length...)._length.
2030 Node* LoadRangeNode::Identity( PhaseTransform *phase ) {
2031 Node* x = LoadINode::Identity(phase);
2032 if (x != this) return x;
2034 // Take apart the address into an oop and and offset.
2035 // Return 'this' if we cannot.
2036 Node* adr = in(MemNode::Address);
2037 intptr_t offset = 0;
2038 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2039 if (base == NULL) return this;
2040 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2041 if (tary == NULL) return this;
2043 // We can fetch the length directly through an AllocateArrayNode.
2044 // This works even if the length is not constant (clone or newArray).
2045 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2046 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2047 if (alloc != NULL) {
2048 Node* allocated_length = alloc->Ideal_length();
2049 // Do not allow make_ideal_length to allocate a CastII node.
2050 Node* len = alloc->make_ideal_length(tary, phase, false);
2051 if (allocated_length == len) {
2052 // Return allocated_length only if it would not be improved by a CastII.
2053 return allocated_length;
2054 }
2055 }
2056 }
2058 return this;
2060 }
2062 //=============================================================================
2063 //---------------------------StoreNode::make-----------------------------------
2064 // Polymorphic factory method:
2065 StoreNode* StoreNode::make( PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt ) {
2066 Compile* C = gvn.C;
2068 switch (bt) {
2069 case T_BOOLEAN:
2070 case T_BYTE: return new (C, 4) StoreBNode(ctl, mem, adr, adr_type, val);
2071 case T_INT: return new (C, 4) StoreINode(ctl, mem, adr, adr_type, val);
2072 case T_CHAR:
2073 case T_SHORT: return new (C, 4) StoreCNode(ctl, mem, adr, adr_type, val);
2074 case T_LONG: return new (C, 4) StoreLNode(ctl, mem, adr, adr_type, val);
2075 case T_FLOAT: return new (C, 4) StoreFNode(ctl, mem, adr, adr_type, val);
2076 case T_DOUBLE: return new (C, 4) StoreDNode(ctl, mem, adr, adr_type, val);
2077 case T_ADDRESS:
2078 case T_OBJECT:
2079 #ifdef _LP64
2080 if (adr->bottom_type()->is_ptr_to_narrowoop() ||
2081 (UseCompressedOops && val->bottom_type()->isa_klassptr() &&
2082 adr->bottom_type()->isa_rawptr())) {
2083 val = gvn.transform(new (C, 2) EncodePNode(val, val->bottom_type()->make_narrowoop()));
2084 return new (C, 4) StoreNNode(ctl, mem, adr, adr_type, val);
2085 } else
2086 #endif
2087 {
2088 return new (C, 4) StorePNode(ctl, mem, adr, adr_type, val);
2089 }
2090 }
2091 ShouldNotReachHere();
2092 return (StoreNode*)NULL;
2093 }
2095 StoreLNode* StoreLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val) {
2096 bool require_atomic = true;
2097 return new (C, 4) StoreLNode(ctl, mem, adr, adr_type, val, require_atomic);
2098 }
2101 //--------------------------bottom_type----------------------------------------
2102 const Type *StoreNode::bottom_type() const {
2103 return Type::MEMORY;
2104 }
2106 //------------------------------hash-------------------------------------------
2107 uint StoreNode::hash() const {
2108 // unroll addition of interesting fields
2109 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2111 // Since they are not commoned, do not hash them:
2112 return NO_HASH;
2113 }
2115 //------------------------------Ideal------------------------------------------
2116 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
2117 // When a store immediately follows a relevant allocation/initialization,
2118 // try to capture it into the initialization, or hoist it above.
2119 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2120 Node* p = MemNode::Ideal_common(phase, can_reshape);
2121 if (p) return (p == NodeSentinel) ? NULL : p;
2123 Node* mem = in(MemNode::Memory);
2124 Node* address = in(MemNode::Address);
2126 // Back-to-back stores to same address? Fold em up.
2127 // Generally unsafe if I have intervening uses...
2128 if (mem->is_Store() && phase->eqv_uncast(mem->in(MemNode::Address), address)) {
2129 // Looking at a dead closed cycle of memory?
2130 assert(mem != mem->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
2132 assert(Opcode() == mem->Opcode() ||
2133 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw,
2134 "no mismatched stores, except on raw memory");
2136 if (mem->outcnt() == 1 && // check for intervening uses
2137 mem->as_Store()->memory_size() <= this->memory_size()) {
2138 // If anybody other than 'this' uses 'mem', we cannot fold 'mem' away.
2139 // For example, 'mem' might be the final state at a conditional return.
2140 // Or, 'mem' might be used by some node which is live at the same time
2141 // 'this' is live, which might be unschedulable. So, require exactly
2142 // ONE user, the 'this' store, until such time as we clone 'mem' for
2143 // each of 'mem's uses (thus making the exactly-1-user-rule hold true).
2144 if (can_reshape) { // (%%% is this an anachronism?)
2145 set_req_X(MemNode::Memory, mem->in(MemNode::Memory),
2146 phase->is_IterGVN());
2147 } else {
2148 // It's OK to do this in the parser, since DU info is always accurate,
2149 // and the parser always refers to nodes via SafePointNode maps.
2150 set_req(MemNode::Memory, mem->in(MemNode::Memory));
2151 }
2152 return this;
2153 }
2154 }
2156 // Capture an unaliased, unconditional, simple store into an initializer.
2157 // Or, if it is independent of the allocation, hoist it above the allocation.
2158 if (ReduceFieldZeroing && /*can_reshape &&*/
2159 mem->is_Proj() && mem->in(0)->is_Initialize()) {
2160 InitializeNode* init = mem->in(0)->as_Initialize();
2161 intptr_t offset = init->can_capture_store(this, phase);
2162 if (offset > 0) {
2163 Node* moved = init->capture_store(this, offset, phase);
2164 // If the InitializeNode captured me, it made a raw copy of me,
2165 // and I need to disappear.
2166 if (moved != NULL) {
2167 // %%% hack to ensure that Ideal returns a new node:
2168 mem = MergeMemNode::make(phase->C, mem);
2169 return mem; // fold me away
2170 }
2171 }
2172 }
2174 return NULL; // No further progress
2175 }
2177 //------------------------------Value-----------------------------------------
2178 const Type *StoreNode::Value( PhaseTransform *phase ) const {
2179 // Either input is TOP ==> the result is TOP
2180 const Type *t1 = phase->type( in(MemNode::Memory) );
2181 if( t1 == Type::TOP ) return Type::TOP;
2182 const Type *t2 = phase->type( in(MemNode::Address) );
2183 if( t2 == Type::TOP ) return Type::TOP;
2184 const Type *t3 = phase->type( in(MemNode::ValueIn) );
2185 if( t3 == Type::TOP ) return Type::TOP;
2186 return Type::MEMORY;
2187 }
2189 //------------------------------Identity---------------------------------------
2190 // Remove redundant stores:
2191 // Store(m, p, Load(m, p)) changes to m.
2192 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
2193 Node *StoreNode::Identity( PhaseTransform *phase ) {
2194 Node* mem = in(MemNode::Memory);
2195 Node* adr = in(MemNode::Address);
2196 Node* val = in(MemNode::ValueIn);
2198 // Load then Store? Then the Store is useless
2199 if (val->is_Load() &&
2200 phase->eqv_uncast( val->in(MemNode::Address), adr ) &&
2201 phase->eqv_uncast( val->in(MemNode::Memory ), mem ) &&
2202 val->as_Load()->store_Opcode() == Opcode()) {
2203 return mem;
2204 }
2206 // Two stores in a row of the same value?
2207 if (mem->is_Store() &&
2208 phase->eqv_uncast( mem->in(MemNode::Address), adr ) &&
2209 phase->eqv_uncast( mem->in(MemNode::ValueIn), val ) &&
2210 mem->Opcode() == Opcode()) {
2211 return mem;
2212 }
2214 // Store of zero anywhere into a freshly-allocated object?
2215 // Then the store is useless.
2216 // (It must already have been captured by the InitializeNode.)
2217 if (ReduceFieldZeroing && phase->type(val)->is_zero_type()) {
2218 // a newly allocated object is already all-zeroes everywhere
2219 if (mem->is_Proj() && mem->in(0)->is_Allocate()) {
2220 return mem;
2221 }
2223 // the store may also apply to zero-bits in an earlier object
2224 Node* prev_mem = find_previous_store(phase);
2225 // Steps (a), (b): Walk past independent stores to find an exact match.
2226 if (prev_mem != NULL) {
2227 Node* prev_val = can_see_stored_value(prev_mem, phase);
2228 if (prev_val != NULL && phase->eqv(prev_val, val)) {
2229 // prev_val and val might differ by a cast; it would be good
2230 // to keep the more informative of the two.
2231 return mem;
2232 }
2233 }
2234 }
2236 return this;
2237 }
2239 //------------------------------match_edge-------------------------------------
2240 // Do we Match on this edge index or not? Match only memory & value
2241 uint StoreNode::match_edge(uint idx) const {
2242 return idx == MemNode::Address || idx == MemNode::ValueIn;
2243 }
2245 //------------------------------cmp--------------------------------------------
2246 // Do not common stores up together. They generally have to be split
2247 // back up anyways, so do not bother.
2248 uint StoreNode::cmp( const Node &n ) const {
2249 return (&n == this); // Always fail except on self
2250 }
2252 //------------------------------Ideal_masked_input-----------------------------
2253 // Check for a useless mask before a partial-word store
2254 // (StoreB ... (AndI valIn conIa) )
2255 // If (conIa & mask == mask) this simplifies to
2256 // (StoreB ... (valIn) )
2257 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
2258 Node *val = in(MemNode::ValueIn);
2259 if( val->Opcode() == Op_AndI ) {
2260 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2261 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
2262 set_req(MemNode::ValueIn, val->in(1));
2263 return this;
2264 }
2265 }
2266 return NULL;
2267 }
2270 //------------------------------Ideal_sign_extended_input----------------------
2271 // Check for useless sign-extension before a partial-word store
2272 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) )
2273 // If (conIL == conIR && conIR <= num_bits) this simplifies to
2274 // (StoreB ... (valIn) )
2275 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) {
2276 Node *val = in(MemNode::ValueIn);
2277 if( val->Opcode() == Op_RShiftI ) {
2278 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2279 if( t && t->is_con() && (t->get_con() <= num_bits) ) {
2280 Node *shl = val->in(1);
2281 if( shl->Opcode() == Op_LShiftI ) {
2282 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int();
2283 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) {
2284 set_req(MemNode::ValueIn, shl->in(1));
2285 return this;
2286 }
2287 }
2288 }
2289 }
2290 return NULL;
2291 }
2293 //------------------------------value_never_loaded-----------------------------------
2294 // Determine whether there are any possible loads of the value stored.
2295 // For simplicity, we actually check if there are any loads from the
2296 // address stored to, not just for loads of the value stored by this node.
2297 //
2298 bool StoreNode::value_never_loaded( PhaseTransform *phase) const {
2299 Node *adr = in(Address);
2300 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
2301 if (adr_oop == NULL)
2302 return false;
2303 if (!adr_oop->is_known_instance_field())
2304 return false; // if not a distinct instance, there may be aliases of the address
2305 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
2306 Node *use = adr->fast_out(i);
2307 int opc = use->Opcode();
2308 if (use->is_Load() || use->is_LoadStore()) {
2309 return false;
2310 }
2311 }
2312 return true;
2313 }
2315 //=============================================================================
2316 //------------------------------Ideal------------------------------------------
2317 // If the store is from an AND mask that leaves the low bits untouched, then
2318 // we can skip the AND operation. If the store is from a sign-extension
2319 // (a left shift, then right shift) we can skip both.
2320 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
2321 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
2322 if( progress != NULL ) return progress;
2324 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
2325 if( progress != NULL ) return progress;
2327 // Finally check the default case
2328 return StoreNode::Ideal(phase, can_reshape);
2329 }
2331 //=============================================================================
2332 //------------------------------Ideal------------------------------------------
2333 // If the store is from an AND mask that leaves the low bits untouched, then
2334 // we can skip the AND operation
2335 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
2336 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
2337 if( progress != NULL ) return progress;
2339 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
2340 if( progress != NULL ) return progress;
2342 // Finally check the default case
2343 return StoreNode::Ideal(phase, can_reshape);
2344 }
2346 //=============================================================================
2347 //------------------------------Identity---------------------------------------
2348 Node *StoreCMNode::Identity( PhaseTransform *phase ) {
2349 // No need to card mark when storing a null ptr
2350 Node* my_store = in(MemNode::OopStore);
2351 if (my_store->is_Store()) {
2352 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) );
2353 if( t1 == TypePtr::NULL_PTR ) {
2354 return in(MemNode::Memory);
2355 }
2356 }
2357 return this;
2358 }
2360 //=============================================================================
2361 //------------------------------Ideal---------------------------------------
2362 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){
2363 Node* progress = StoreNode::Ideal(phase, can_reshape);
2364 if (progress != NULL) return progress;
2366 Node* my_store = in(MemNode::OopStore);
2367 if (my_store->is_MergeMem()) {
2368 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx());
2369 set_req(MemNode::OopStore, mem);
2370 return this;
2371 }
2373 return NULL;
2374 }
2376 //------------------------------Value-----------------------------------------
2377 const Type *StoreCMNode::Value( PhaseTransform *phase ) const {
2378 // Either input is TOP ==> the result is TOP
2379 const Type *t = phase->type( in(MemNode::Memory) );
2380 if( t == Type::TOP ) return Type::TOP;
2381 t = phase->type( in(MemNode::Address) );
2382 if( t == Type::TOP ) return Type::TOP;
2383 t = phase->type( in(MemNode::ValueIn) );
2384 if( t == Type::TOP ) return Type::TOP;
2385 // If extra input is TOP ==> the result is TOP
2386 t = phase->type( in(MemNode::OopStore) );
2387 if( t == Type::TOP ) return Type::TOP;
2389 return StoreNode::Value( phase );
2390 }
2393 //=============================================================================
2394 //----------------------------------SCMemProjNode------------------------------
2395 const Type * SCMemProjNode::Value( PhaseTransform *phase ) const
2396 {
2397 return bottom_type();
2398 }
2400 //=============================================================================
2401 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : Node(5) {
2402 init_req(MemNode::Control, c );
2403 init_req(MemNode::Memory , mem);
2404 init_req(MemNode::Address, adr);
2405 init_req(MemNode::ValueIn, val);
2406 init_req( ExpectedIn, ex );
2407 init_class_id(Class_LoadStore);
2409 }
2411 //=============================================================================
2412 //-------------------------------adr_type--------------------------------------
2413 // Do we Match on this edge index or not? Do not match memory
2414 const TypePtr* ClearArrayNode::adr_type() const {
2415 Node *adr = in(3);
2416 return MemNode::calculate_adr_type(adr->bottom_type());
2417 }
2419 //------------------------------match_edge-------------------------------------
2420 // Do we Match on this edge index or not? Do not match memory
2421 uint ClearArrayNode::match_edge(uint idx) const {
2422 return idx > 1;
2423 }
2425 //------------------------------Identity---------------------------------------
2426 // Clearing a zero length array does nothing
2427 Node *ClearArrayNode::Identity( PhaseTransform *phase ) {
2428 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
2429 }
2431 //------------------------------Idealize---------------------------------------
2432 // Clearing a short array is faster with stores
2433 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape){
2434 const int unit = BytesPerLong;
2435 const TypeX* t = phase->type(in(2))->isa_intptr_t();
2436 if (!t) return NULL;
2437 if (!t->is_con()) return NULL;
2438 intptr_t raw_count = t->get_con();
2439 intptr_t size = raw_count;
2440 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
2441 // Clearing nothing uses the Identity call.
2442 // Negative clears are possible on dead ClearArrays
2443 // (see jck test stmt114.stmt11402.val).
2444 if (size <= 0 || size % unit != 0) return NULL;
2445 intptr_t count = size / unit;
2446 // Length too long; use fast hardware clear
2447 if (size > Matcher::init_array_short_size) return NULL;
2448 Node *mem = in(1);
2449 if( phase->type(mem)==Type::TOP ) return NULL;
2450 Node *adr = in(3);
2451 const Type* at = phase->type(adr);
2452 if( at==Type::TOP ) return NULL;
2453 const TypePtr* atp = at->isa_ptr();
2454 // adjust atp to be the correct array element address type
2455 if (atp == NULL) atp = TypePtr::BOTTOM;
2456 else atp = atp->add_offset(Type::OffsetBot);
2457 // Get base for derived pointer purposes
2458 if( adr->Opcode() != Op_AddP ) Unimplemented();
2459 Node *base = adr->in(1);
2461 Node *zero = phase->makecon(TypeLong::ZERO);
2462 Node *off = phase->MakeConX(BytesPerLong);
2463 mem = new (phase->C, 4) StoreLNode(in(0),mem,adr,atp,zero);
2464 count--;
2465 while( count-- ) {
2466 mem = phase->transform(mem);
2467 adr = phase->transform(new (phase->C, 4) AddPNode(base,adr,off));
2468 mem = new (phase->C, 4) StoreLNode(in(0),mem,adr,atp,zero);
2469 }
2470 return mem;
2471 }
2473 //----------------------------step_through----------------------------------
2474 // Return allocation input memory edge if it is different instance
2475 // or itself if it is the one we are looking for.
2476 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) {
2477 Node* n = *np;
2478 assert(n->is_ClearArray(), "sanity");
2479 intptr_t offset;
2480 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
2481 // This method is called only before Allocate nodes are expanded during
2482 // macro nodes expansion. Before that ClearArray nodes are only generated
2483 // in LibraryCallKit::generate_arraycopy() which follows allocations.
2484 assert(alloc != NULL, "should have allocation");
2485 if (alloc->_idx == instance_id) {
2486 // Can not bypass initialization of the instance we are looking for.
2487 return false;
2488 }
2489 // Otherwise skip it.
2490 InitializeNode* init = alloc->initialization();
2491 if (init != NULL)
2492 *np = init->in(TypeFunc::Memory);
2493 else
2494 *np = alloc->in(TypeFunc::Memory);
2495 return true;
2496 }
2498 //----------------------------clear_memory-------------------------------------
2499 // Generate code to initialize object storage to zero.
2500 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2501 intptr_t start_offset,
2502 Node* end_offset,
2503 PhaseGVN* phase) {
2504 Compile* C = phase->C;
2505 intptr_t offset = start_offset;
2507 int unit = BytesPerLong;
2508 if ((offset % unit) != 0) {
2509 Node* adr = new (C, 4) AddPNode(dest, dest, phase->MakeConX(offset));
2510 adr = phase->transform(adr);
2511 const TypePtr* atp = TypeRawPtr::BOTTOM;
2512 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT);
2513 mem = phase->transform(mem);
2514 offset += BytesPerInt;
2515 }
2516 assert((offset % unit) == 0, "");
2518 // Initialize the remaining stuff, if any, with a ClearArray.
2519 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase);
2520 }
2522 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2523 Node* start_offset,
2524 Node* end_offset,
2525 PhaseGVN* phase) {
2526 if (start_offset == end_offset) {
2527 // nothing to do
2528 return mem;
2529 }
2531 Compile* C = phase->C;
2532 int unit = BytesPerLong;
2533 Node* zbase = start_offset;
2534 Node* zend = end_offset;
2536 // Scale to the unit required by the CPU:
2537 if (!Matcher::init_array_count_is_in_bytes) {
2538 Node* shift = phase->intcon(exact_log2(unit));
2539 zbase = phase->transform( new(C,3) URShiftXNode(zbase, shift) );
2540 zend = phase->transform( new(C,3) URShiftXNode(zend, shift) );
2541 }
2543 Node* zsize = phase->transform( new(C,3) SubXNode(zend, zbase) );
2544 Node* zinit = phase->zerocon((unit == BytesPerLong) ? T_LONG : T_INT);
2546 // Bulk clear double-words
2547 Node* adr = phase->transform( new(C,4) AddPNode(dest, dest, start_offset) );
2548 mem = new (C, 4) ClearArrayNode(ctl, mem, zsize, adr);
2549 return phase->transform(mem);
2550 }
2552 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2553 intptr_t start_offset,
2554 intptr_t end_offset,
2555 PhaseGVN* phase) {
2556 if (start_offset == end_offset) {
2557 // nothing to do
2558 return mem;
2559 }
2561 Compile* C = phase->C;
2562 assert((end_offset % BytesPerInt) == 0, "odd end offset");
2563 intptr_t done_offset = end_offset;
2564 if ((done_offset % BytesPerLong) != 0) {
2565 done_offset -= BytesPerInt;
2566 }
2567 if (done_offset > start_offset) {
2568 mem = clear_memory(ctl, mem, dest,
2569 start_offset, phase->MakeConX(done_offset), phase);
2570 }
2571 if (done_offset < end_offset) { // emit the final 32-bit store
2572 Node* adr = new (C, 4) AddPNode(dest, dest, phase->MakeConX(done_offset));
2573 adr = phase->transform(adr);
2574 const TypePtr* atp = TypeRawPtr::BOTTOM;
2575 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT);
2576 mem = phase->transform(mem);
2577 done_offset += BytesPerInt;
2578 }
2579 assert(done_offset == end_offset, "");
2580 return mem;
2581 }
2583 //=============================================================================
2584 // Do we match on this edge? No memory edges
2585 uint StrCompNode::match_edge(uint idx) const {
2586 return idx == 2 || idx == 3; // StrComp (Binary str1 cnt1) (Binary str2 cnt2)
2587 }
2589 //------------------------------Ideal------------------------------------------
2590 // Return a node which is more "ideal" than the current node. Strip out
2591 // control copies
2592 Node *StrCompNode::Ideal(PhaseGVN *phase, bool can_reshape){
2593 return remove_dead_region(phase, can_reshape) ? this : NULL;
2594 }
2596 //=============================================================================
2597 // Do we match on this edge? No memory edges
2598 uint StrEqualsNode::match_edge(uint idx) const {
2599 return idx == 2 || idx == 3; // StrEquals (Binary str1 str2) cnt
2600 }
2602 //------------------------------Ideal------------------------------------------
2603 // Return a node which is more "ideal" than the current node. Strip out
2604 // control copies
2605 Node *StrEqualsNode::Ideal(PhaseGVN *phase, bool can_reshape){
2606 return remove_dead_region(phase, can_reshape) ? this : NULL;
2607 }
2609 //=============================================================================
2610 // Do we match on this edge? No memory edges
2611 uint StrIndexOfNode::match_edge(uint idx) const {
2612 return idx == 2 || idx == 3; // StrIndexOf (Binary str1 cnt1) (Binary str2 cnt2)
2613 }
2615 //------------------------------Ideal------------------------------------------
2616 // Return a node which is more "ideal" than the current node. Strip out
2617 // control copies
2618 Node *StrIndexOfNode::Ideal(PhaseGVN *phase, bool can_reshape){
2619 return remove_dead_region(phase, can_reshape) ? this : NULL;
2620 }
2622 //=============================================================================
2623 // Do we match on this edge? No memory edges
2624 uint AryEqNode::match_edge(uint idx) const {
2625 return idx == 2 || idx == 3; // StrEquals ary1 ary2
2626 }
2627 //------------------------------Ideal------------------------------------------
2628 // Return a node which is more "ideal" than the current node. Strip out
2629 // control copies
2630 Node *AryEqNode::Ideal(PhaseGVN *phase, bool can_reshape){
2631 return remove_dead_region(phase, can_reshape) ? this : NULL;
2632 }
2634 //=============================================================================
2635 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
2636 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)),
2637 _adr_type(C->get_adr_type(alias_idx))
2638 {
2639 init_class_id(Class_MemBar);
2640 Node* top = C->top();
2641 init_req(TypeFunc::I_O,top);
2642 init_req(TypeFunc::FramePtr,top);
2643 init_req(TypeFunc::ReturnAdr,top);
2644 if (precedent != NULL)
2645 init_req(TypeFunc::Parms, precedent);
2646 }
2648 //------------------------------cmp--------------------------------------------
2649 uint MemBarNode::hash() const { return NO_HASH; }
2650 uint MemBarNode::cmp( const Node &n ) const {
2651 return (&n == this); // Always fail except on self
2652 }
2654 //------------------------------make-------------------------------------------
2655 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
2656 int len = Precedent + (pn == NULL? 0: 1);
2657 switch (opcode) {
2658 case Op_MemBarAcquire: return new(C, len) MemBarAcquireNode(C, atp, pn);
2659 case Op_MemBarRelease: return new(C, len) MemBarReleaseNode(C, atp, pn);
2660 case Op_MemBarVolatile: return new(C, len) MemBarVolatileNode(C, atp, pn);
2661 case Op_MemBarCPUOrder: return new(C, len) MemBarCPUOrderNode(C, atp, pn);
2662 case Op_Initialize: return new(C, len) InitializeNode(C, atp, pn);
2663 default: ShouldNotReachHere(); return NULL;
2664 }
2665 }
2667 //------------------------------Ideal------------------------------------------
2668 // Return a node which is more "ideal" than the current node. Strip out
2669 // control copies
2670 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2671 if (remove_dead_region(phase, can_reshape)) return this;
2673 // Eliminate volatile MemBars for scalar replaced objects.
2674 if (can_reshape && req() == (Precedent+1) &&
2675 (Opcode() == Op_MemBarAcquire || Opcode() == Op_MemBarVolatile)) {
2676 // Volatile field loads and stores.
2677 Node* my_mem = in(MemBarNode::Precedent);
2678 if (my_mem != NULL && my_mem->is_Mem()) {
2679 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
2680 // Check for scalar replaced object reference.
2681 if( t_oop != NULL && t_oop->is_known_instance_field() &&
2682 t_oop->offset() != Type::OffsetBot &&
2683 t_oop->offset() != Type::OffsetTop) {
2684 // Replace MemBar projections by its inputs.
2685 PhaseIterGVN* igvn = phase->is_IterGVN();
2686 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
2687 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
2688 // Must return either the original node (now dead) or a new node
2689 // (Do not return a top here, since that would break the uniqueness of top.)
2690 return new (phase->C, 1) ConINode(TypeInt::ZERO);
2691 }
2692 }
2693 }
2694 return NULL;
2695 }
2697 //------------------------------Value------------------------------------------
2698 const Type *MemBarNode::Value( PhaseTransform *phase ) const {
2699 if( !in(0) ) return Type::TOP;
2700 if( phase->type(in(0)) == Type::TOP )
2701 return Type::TOP;
2702 return TypeTuple::MEMBAR;
2703 }
2705 //------------------------------match------------------------------------------
2706 // Construct projections for memory.
2707 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) {
2708 switch (proj->_con) {
2709 case TypeFunc::Control:
2710 case TypeFunc::Memory:
2711 return new (m->C, 1) MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
2712 }
2713 ShouldNotReachHere();
2714 return NULL;
2715 }
2717 //===========================InitializeNode====================================
2718 // SUMMARY:
2719 // This node acts as a memory barrier on raw memory, after some raw stores.
2720 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
2721 // The Initialize can 'capture' suitably constrained stores as raw inits.
2722 // It can coalesce related raw stores into larger units (called 'tiles').
2723 // It can avoid zeroing new storage for memory units which have raw inits.
2724 // At macro-expansion, it is marked 'complete', and does not optimize further.
2725 //
2726 // EXAMPLE:
2727 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
2728 // ctl = incoming control; mem* = incoming memory
2729 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
2730 // First allocate uninitialized memory and fill in the header:
2731 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
2732 // ctl := alloc.Control; mem* := alloc.Memory*
2733 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
2734 // Then initialize to zero the non-header parts of the raw memory block:
2735 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
2736 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
2737 // After the initialize node executes, the object is ready for service:
2738 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
2739 // Suppose its body is immediately initialized as {1,2}:
2740 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
2741 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
2742 // mem.SLICE(#short[*]) := store2
2743 //
2744 // DETAILS:
2745 // An InitializeNode collects and isolates object initialization after
2746 // an AllocateNode and before the next possible safepoint. As a
2747 // memory barrier (MemBarNode), it keeps critical stores from drifting
2748 // down past any safepoint or any publication of the allocation.
2749 // Before this barrier, a newly-allocated object may have uninitialized bits.
2750 // After this barrier, it may be treated as a real oop, and GC is allowed.
2751 //
2752 // The semantics of the InitializeNode include an implicit zeroing of
2753 // the new object from object header to the end of the object.
2754 // (The object header and end are determined by the AllocateNode.)
2755 //
2756 // Certain stores may be added as direct inputs to the InitializeNode.
2757 // These stores must update raw memory, and they must be to addresses
2758 // derived from the raw address produced by AllocateNode, and with
2759 // a constant offset. They must be ordered by increasing offset.
2760 // The first one is at in(RawStores), the last at in(req()-1).
2761 // Unlike most memory operations, they are not linked in a chain,
2762 // but are displayed in parallel as users of the rawmem output of
2763 // the allocation.
2764 //
2765 // (See comments in InitializeNode::capture_store, which continue
2766 // the example given above.)
2767 //
2768 // When the associated Allocate is macro-expanded, the InitializeNode
2769 // may be rewritten to optimize collected stores. A ClearArrayNode
2770 // may also be created at that point to represent any required zeroing.
2771 // The InitializeNode is then marked 'complete', prohibiting further
2772 // capturing of nearby memory operations.
2773 //
2774 // During macro-expansion, all captured initializations which store
2775 // constant values of 32 bits or smaller are coalesced (if advantageous)
2776 // into larger 'tiles' 32 or 64 bits. This allows an object to be
2777 // initialized in fewer memory operations. Memory words which are
2778 // covered by neither tiles nor non-constant stores are pre-zeroed
2779 // by explicit stores of zero. (The code shape happens to do all
2780 // zeroing first, then all other stores, with both sequences occurring
2781 // in order of ascending offsets.)
2782 //
2783 // Alternatively, code may be inserted between an AllocateNode and its
2784 // InitializeNode, to perform arbitrary initialization of the new object.
2785 // E.g., the object copying intrinsics insert complex data transfers here.
2786 // The initialization must then be marked as 'complete' disable the
2787 // built-in zeroing semantics and the collection of initializing stores.
2788 //
2789 // While an InitializeNode is incomplete, reads from the memory state
2790 // produced by it are optimizable if they match the control edge and
2791 // new oop address associated with the allocation/initialization.
2792 // They return a stored value (if the offset matches) or else zero.
2793 // A write to the memory state, if it matches control and address,
2794 // and if it is to a constant offset, may be 'captured' by the
2795 // InitializeNode. It is cloned as a raw memory operation and rewired
2796 // inside the initialization, to the raw oop produced by the allocation.
2797 // Operations on addresses which are provably distinct (e.g., to
2798 // other AllocateNodes) are allowed to bypass the initialization.
2799 //
2800 // The effect of all this is to consolidate object initialization
2801 // (both arrays and non-arrays, both piecewise and bulk) into a
2802 // single location, where it can be optimized as a unit.
2803 //
2804 // Only stores with an offset less than TrackedInitializationLimit words
2805 // will be considered for capture by an InitializeNode. This puts a
2806 // reasonable limit on the complexity of optimized initializations.
2808 //---------------------------InitializeNode------------------------------------
2809 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
2810 : _is_complete(false),
2811 MemBarNode(C, adr_type, rawoop)
2812 {
2813 init_class_id(Class_Initialize);
2815 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
2816 assert(in(RawAddress) == rawoop, "proper init");
2817 // Note: allocation() can be NULL, for secondary initialization barriers
2818 }
2820 // Since this node is not matched, it will be processed by the
2821 // register allocator. Declare that there are no constraints
2822 // on the allocation of the RawAddress edge.
2823 const RegMask &InitializeNode::in_RegMask(uint idx) const {
2824 // This edge should be set to top, by the set_complete. But be conservative.
2825 if (idx == InitializeNode::RawAddress)
2826 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
2827 return RegMask::Empty;
2828 }
2830 Node* InitializeNode::memory(uint alias_idx) {
2831 Node* mem = in(Memory);
2832 if (mem->is_MergeMem()) {
2833 return mem->as_MergeMem()->memory_at(alias_idx);
2834 } else {
2835 // incoming raw memory is not split
2836 return mem;
2837 }
2838 }
2840 bool InitializeNode::is_non_zero() {
2841 if (is_complete()) return false;
2842 remove_extra_zeroes();
2843 return (req() > RawStores);
2844 }
2846 void InitializeNode::set_complete(PhaseGVN* phase) {
2847 assert(!is_complete(), "caller responsibility");
2848 _is_complete = true;
2850 // After this node is complete, it contains a bunch of
2851 // raw-memory initializations. There is no need for
2852 // it to have anything to do with non-raw memory effects.
2853 // Therefore, tell all non-raw users to re-optimize themselves,
2854 // after skipping the memory effects of this initialization.
2855 PhaseIterGVN* igvn = phase->is_IterGVN();
2856 if (igvn) igvn->add_users_to_worklist(this);
2857 }
2859 // convenience function
2860 // return false if the init contains any stores already
2861 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
2862 InitializeNode* init = initialization();
2863 if (init == NULL || init->is_complete()) return false;
2864 init->remove_extra_zeroes();
2865 // for now, if this allocation has already collected any inits, bail:
2866 if (init->is_non_zero()) return false;
2867 init->set_complete(phase);
2868 return true;
2869 }
2871 void InitializeNode::remove_extra_zeroes() {
2872 if (req() == RawStores) return;
2873 Node* zmem = zero_memory();
2874 uint fill = RawStores;
2875 for (uint i = fill; i < req(); i++) {
2876 Node* n = in(i);
2877 if (n->is_top() || n == zmem) continue; // skip
2878 if (fill < i) set_req(fill, n); // compact
2879 ++fill;
2880 }
2881 // delete any empty spaces created:
2882 while (fill < req()) {
2883 del_req(fill);
2884 }
2885 }
2887 // Helper for remembering which stores go with which offsets.
2888 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) {
2889 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
2890 intptr_t offset = -1;
2891 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
2892 phase, offset);
2893 if (base == NULL) return -1; // something is dead,
2894 if (offset < 0) return -1; // dead, dead
2895 return offset;
2896 }
2898 // Helper for proving that an initialization expression is
2899 // "simple enough" to be folded into an object initialization.
2900 // Attempts to prove that a store's initial value 'n' can be captured
2901 // within the initialization without creating a vicious cycle, such as:
2902 // { Foo p = new Foo(); p.next = p; }
2903 // True for constants and parameters and small combinations thereof.
2904 bool InitializeNode::detect_init_independence(Node* n,
2905 bool st_is_pinned,
2906 int& count) {
2907 if (n == NULL) return true; // (can this really happen?)
2908 if (n->is_Proj()) n = n->in(0);
2909 if (n == this) return false; // found a cycle
2910 if (n->is_Con()) return true;
2911 if (n->is_Start()) return true; // params, etc., are OK
2912 if (n->is_Root()) return true; // even better
2914 Node* ctl = n->in(0);
2915 if (ctl != NULL && !ctl->is_top()) {
2916 if (ctl->is_Proj()) ctl = ctl->in(0);
2917 if (ctl == this) return false;
2919 // If we already know that the enclosing memory op is pinned right after
2920 // the init, then any control flow that the store has picked up
2921 // must have preceded the init, or else be equal to the init.
2922 // Even after loop optimizations (which might change control edges)
2923 // a store is never pinned *before* the availability of its inputs.
2924 if (!MemNode::all_controls_dominate(n, this))
2925 return false; // failed to prove a good control
2927 }
2929 // Check data edges for possible dependencies on 'this'.
2930 if ((count += 1) > 20) return false; // complexity limit
2931 for (uint i = 1; i < n->req(); i++) {
2932 Node* m = n->in(i);
2933 if (m == NULL || m == n || m->is_top()) continue;
2934 uint first_i = n->find_edge(m);
2935 if (i != first_i) continue; // process duplicate edge just once
2936 if (!detect_init_independence(m, st_is_pinned, count)) {
2937 return false;
2938 }
2939 }
2941 return true;
2942 }
2944 // Here are all the checks a Store must pass before it can be moved into
2945 // an initialization. Returns zero if a check fails.
2946 // On success, returns the (constant) offset to which the store applies,
2947 // within the initialized memory.
2948 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase) {
2949 const int FAIL = 0;
2950 if (st->req() != MemNode::ValueIn + 1)
2951 return FAIL; // an inscrutable StoreNode (card mark?)
2952 Node* ctl = st->in(MemNode::Control);
2953 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this))
2954 return FAIL; // must be unconditional after the initialization
2955 Node* mem = st->in(MemNode::Memory);
2956 if (!(mem->is_Proj() && mem->in(0) == this))
2957 return FAIL; // must not be preceded by other stores
2958 Node* adr = st->in(MemNode::Address);
2959 intptr_t offset;
2960 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
2961 if (alloc == NULL)
2962 return FAIL; // inscrutable address
2963 if (alloc != allocation())
2964 return FAIL; // wrong allocation! (store needs to float up)
2965 Node* val = st->in(MemNode::ValueIn);
2966 int complexity_count = 0;
2967 if (!detect_init_independence(val, true, complexity_count))
2968 return FAIL; // stored value must be 'simple enough'
2970 return offset; // success
2971 }
2973 // Find the captured store in(i) which corresponds to the range
2974 // [start..start+size) in the initialized object.
2975 // If there is one, return its index i. If there isn't, return the
2976 // negative of the index where it should be inserted.
2977 // Return 0 if the queried range overlaps an initialization boundary
2978 // or if dead code is encountered.
2979 // If size_in_bytes is zero, do not bother with overlap checks.
2980 int InitializeNode::captured_store_insertion_point(intptr_t start,
2981 int size_in_bytes,
2982 PhaseTransform* phase) {
2983 const int FAIL = 0, MAX_STORE = BytesPerLong;
2985 if (is_complete())
2986 return FAIL; // arraycopy got here first; punt
2988 assert(allocation() != NULL, "must be present");
2990 // no negatives, no header fields:
2991 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
2993 // after a certain size, we bail out on tracking all the stores:
2994 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
2995 if (start >= ti_limit) return FAIL;
2997 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
2998 if (i >= limit) return -(int)i; // not found; here is where to put it
3000 Node* st = in(i);
3001 intptr_t st_off = get_store_offset(st, phase);
3002 if (st_off < 0) {
3003 if (st != zero_memory()) {
3004 return FAIL; // bail out if there is dead garbage
3005 }
3006 } else if (st_off > start) {
3007 // ...we are done, since stores are ordered
3008 if (st_off < start + size_in_bytes) {
3009 return FAIL; // the next store overlaps
3010 }
3011 return -(int)i; // not found; here is where to put it
3012 } else if (st_off < start) {
3013 if (size_in_bytes != 0 &&
3014 start < st_off + MAX_STORE &&
3015 start < st_off + st->as_Store()->memory_size()) {
3016 return FAIL; // the previous store overlaps
3017 }
3018 } else {
3019 if (size_in_bytes != 0 &&
3020 st->as_Store()->memory_size() != size_in_bytes) {
3021 return FAIL; // mismatched store size
3022 }
3023 return i;
3024 }
3026 ++i;
3027 }
3028 }
3030 // Look for a captured store which initializes at the offset 'start'
3031 // with the given size. If there is no such store, and no other
3032 // initialization interferes, then return zero_memory (the memory
3033 // projection of the AllocateNode).
3034 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
3035 PhaseTransform* phase) {
3036 assert(stores_are_sane(phase), "");
3037 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3038 if (i == 0) {
3039 return NULL; // something is dead
3040 } else if (i < 0) {
3041 return zero_memory(); // just primordial zero bits here
3042 } else {
3043 Node* st = in(i); // here is the store at this position
3044 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
3045 return st;
3046 }
3047 }
3049 // Create, as a raw pointer, an address within my new object at 'offset'.
3050 Node* InitializeNode::make_raw_address(intptr_t offset,
3051 PhaseTransform* phase) {
3052 Node* addr = in(RawAddress);
3053 if (offset != 0) {
3054 Compile* C = phase->C;
3055 addr = phase->transform( new (C, 4) AddPNode(C->top(), addr,
3056 phase->MakeConX(offset)) );
3057 }
3058 return addr;
3059 }
3061 // Clone the given store, converting it into a raw store
3062 // initializing a field or element of my new object.
3063 // Caller is responsible for retiring the original store,
3064 // with subsume_node or the like.
3065 //
3066 // From the example above InitializeNode::InitializeNode,
3067 // here are the old stores to be captured:
3068 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3069 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3070 //
3071 // Here is the changed code; note the extra edges on init:
3072 // alloc = (Allocate ...)
3073 // rawoop = alloc.RawAddress
3074 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
3075 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
3076 // init = (Initialize alloc.Control alloc.Memory rawoop
3077 // rawstore1 rawstore2)
3078 //
3079 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
3080 PhaseTransform* phase) {
3081 assert(stores_are_sane(phase), "");
3083 if (start < 0) return NULL;
3084 assert(can_capture_store(st, phase) == start, "sanity");
3086 Compile* C = phase->C;
3087 int size_in_bytes = st->memory_size();
3088 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3089 if (i == 0) return NULL; // bail out
3090 Node* prev_mem = NULL; // raw memory for the captured store
3091 if (i > 0) {
3092 prev_mem = in(i); // there is a pre-existing store under this one
3093 set_req(i, C->top()); // temporarily disconnect it
3094 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
3095 } else {
3096 i = -i; // no pre-existing store
3097 prev_mem = zero_memory(); // a slice of the newly allocated object
3098 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
3099 set_req(--i, C->top()); // reuse this edge; it has been folded away
3100 else
3101 ins_req(i, C->top()); // build a new edge
3102 }
3103 Node* new_st = st->clone();
3104 new_st->set_req(MemNode::Control, in(Control));
3105 new_st->set_req(MemNode::Memory, prev_mem);
3106 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
3107 new_st = phase->transform(new_st);
3109 // At this point, new_st might have swallowed a pre-existing store
3110 // at the same offset, or perhaps new_st might have disappeared,
3111 // if it redundantly stored the same value (or zero to fresh memory).
3113 // In any case, wire it in:
3114 set_req(i, new_st);
3116 // The caller may now kill the old guy.
3117 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
3118 assert(check_st == new_st || check_st == NULL, "must be findable");
3119 assert(!is_complete(), "");
3120 return new_st;
3121 }
3123 static bool store_constant(jlong* tiles, int num_tiles,
3124 intptr_t st_off, int st_size,
3125 jlong con) {
3126 if ((st_off & (st_size-1)) != 0)
3127 return false; // strange store offset (assume size==2**N)
3128 address addr = (address)tiles + st_off;
3129 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
3130 switch (st_size) {
3131 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
3132 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
3133 case sizeof(jint): *(jint*) addr = (jint) con; break;
3134 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
3135 default: return false; // strange store size (detect size!=2**N here)
3136 }
3137 return true; // return success to caller
3138 }
3140 // Coalesce subword constants into int constants and possibly
3141 // into long constants. The goal, if the CPU permits,
3142 // is to initialize the object with a small number of 64-bit tiles.
3143 // Also, convert floating-point constants to bit patterns.
3144 // Non-constants are not relevant to this pass.
3145 //
3146 // In terms of the running example on InitializeNode::InitializeNode
3147 // and InitializeNode::capture_store, here is the transformation
3148 // of rawstore1 and rawstore2 into rawstore12:
3149 // alloc = (Allocate ...)
3150 // rawoop = alloc.RawAddress
3151 // tile12 = 0x00010002
3152 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
3153 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
3154 //
3155 void
3156 InitializeNode::coalesce_subword_stores(intptr_t header_size,
3157 Node* size_in_bytes,
3158 PhaseGVN* phase) {
3159 Compile* C = phase->C;
3161 assert(stores_are_sane(phase), "");
3162 // Note: After this pass, they are not completely sane,
3163 // since there may be some overlaps.
3165 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
3167 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3168 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
3169 size_limit = MIN2(size_limit, ti_limit);
3170 size_limit = align_size_up(size_limit, BytesPerLong);
3171 int num_tiles = size_limit / BytesPerLong;
3173 // allocate space for the tile map:
3174 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
3175 jlong tiles_buf[small_len];
3176 Node* nodes_buf[small_len];
3177 jlong inits_buf[small_len];
3178 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
3179 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3180 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
3181 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
3182 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
3183 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3184 // tiles: exact bitwise model of all primitive constants
3185 // nodes: last constant-storing node subsumed into the tiles model
3186 // inits: which bytes (in each tile) are touched by any initializations
3188 //// Pass A: Fill in the tile model with any relevant stores.
3190 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
3191 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
3192 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
3193 Node* zmem = zero_memory(); // initially zero memory state
3194 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3195 Node* st = in(i);
3196 intptr_t st_off = get_store_offset(st, phase);
3198 // Figure out the store's offset and constant value:
3199 if (st_off < header_size) continue; //skip (ignore header)
3200 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
3201 int st_size = st->as_Store()->memory_size();
3202 if (st_off + st_size > size_limit) break;
3204 // Record which bytes are touched, whether by constant or not.
3205 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
3206 continue; // skip (strange store size)
3208 const Type* val = phase->type(st->in(MemNode::ValueIn));
3209 if (!val->singleton()) continue; //skip (non-con store)
3210 BasicType type = val->basic_type();
3212 jlong con = 0;
3213 switch (type) {
3214 case T_INT: con = val->is_int()->get_con(); break;
3215 case T_LONG: con = val->is_long()->get_con(); break;
3216 case T_FLOAT: con = jint_cast(val->getf()); break;
3217 case T_DOUBLE: con = jlong_cast(val->getd()); break;
3218 default: continue; //skip (odd store type)
3219 }
3221 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
3222 st->Opcode() == Op_StoreL) {
3223 continue; // This StoreL is already optimal.
3224 }
3226 // Store down the constant.
3227 store_constant(tiles, num_tiles, st_off, st_size, con);
3229 intptr_t j = st_off >> LogBytesPerLong;
3231 if (type == T_INT && st_size == BytesPerInt
3232 && (st_off & BytesPerInt) == BytesPerInt) {
3233 jlong lcon = tiles[j];
3234 if (!Matcher::isSimpleConstant64(lcon) &&
3235 st->Opcode() == Op_StoreI) {
3236 // This StoreI is already optimal by itself.
3237 jint* intcon = (jint*) &tiles[j];
3238 intcon[1] = 0; // undo the store_constant()
3240 // If the previous store is also optimal by itself, back up and
3241 // undo the action of the previous loop iteration... if we can.
3242 // But if we can't, just let the previous half take care of itself.
3243 st = nodes[j];
3244 st_off -= BytesPerInt;
3245 con = intcon[0];
3246 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) {
3247 assert(st_off >= header_size, "still ignoring header");
3248 assert(get_store_offset(st, phase) == st_off, "must be");
3249 assert(in(i-1) == zmem, "must be");
3250 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
3251 assert(con == tcon->is_int()->get_con(), "must be");
3252 // Undo the effects of the previous loop trip, which swallowed st:
3253 intcon[0] = 0; // undo store_constant()
3254 set_req(i-1, st); // undo set_req(i, zmem)
3255 nodes[j] = NULL; // undo nodes[j] = st
3256 --old_subword; // undo ++old_subword
3257 }
3258 continue; // This StoreI is already optimal.
3259 }
3260 }
3262 // This store is not needed.
3263 set_req(i, zmem);
3264 nodes[j] = st; // record for the moment
3265 if (st_size < BytesPerLong) // something has changed
3266 ++old_subword; // includes int/float, but who's counting...
3267 else ++old_long;
3268 }
3270 if ((old_subword + old_long) == 0)
3271 return; // nothing more to do
3273 //// Pass B: Convert any non-zero tiles into optimal constant stores.
3274 // Be sure to insert them before overlapping non-constant stores.
3275 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
3276 for (int j = 0; j < num_tiles; j++) {
3277 jlong con = tiles[j];
3278 jlong init = inits[j];
3279 if (con == 0) continue;
3280 jint con0, con1; // split the constant, address-wise
3281 jint init0, init1; // split the init map, address-wise
3282 { union { jlong con; jint intcon[2]; } u;
3283 u.con = con;
3284 con0 = u.intcon[0];
3285 con1 = u.intcon[1];
3286 u.con = init;
3287 init0 = u.intcon[0];
3288 init1 = u.intcon[1];
3289 }
3291 Node* old = nodes[j];
3292 assert(old != NULL, "need the prior store");
3293 intptr_t offset = (j * BytesPerLong);
3295 bool split = !Matcher::isSimpleConstant64(con);
3297 if (offset < header_size) {
3298 assert(offset + BytesPerInt >= header_size, "second int counts");
3299 assert(*(jint*)&tiles[j] == 0, "junk in header");
3300 split = true; // only the second word counts
3301 // Example: int a[] = { 42 ... }
3302 } else if (con0 == 0 && init0 == -1) {
3303 split = true; // first word is covered by full inits
3304 // Example: int a[] = { ... foo(), 42 ... }
3305 } else if (con1 == 0 && init1 == -1) {
3306 split = true; // second word is covered by full inits
3307 // Example: int a[] = { ... 42, foo() ... }
3308 }
3310 // Here's a case where init0 is neither 0 nor -1:
3311 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
3312 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
3313 // In this case the tile is not split; it is (jlong)42.
3314 // The big tile is stored down, and then the foo() value is inserted.
3315 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
3317 Node* ctl = old->in(MemNode::Control);
3318 Node* adr = make_raw_address(offset, phase);
3319 const TypePtr* atp = TypeRawPtr::BOTTOM;
3321 // One or two coalesced stores to plop down.
3322 Node* st[2];
3323 intptr_t off[2];
3324 int nst = 0;
3325 if (!split) {
3326 ++new_long;
3327 off[nst] = offset;
3328 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3329 phase->longcon(con), T_LONG);
3330 } else {
3331 // Omit either if it is a zero.
3332 if (con0 != 0) {
3333 ++new_int;
3334 off[nst] = offset;
3335 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3336 phase->intcon(con0), T_INT);
3337 }
3338 if (con1 != 0) {
3339 ++new_int;
3340 offset += BytesPerInt;
3341 adr = make_raw_address(offset, phase);
3342 off[nst] = offset;
3343 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3344 phase->intcon(con1), T_INT);
3345 }
3346 }
3348 // Insert second store first, then the first before the second.
3349 // Insert each one just before any overlapping non-constant stores.
3350 while (nst > 0) {
3351 Node* st1 = st[--nst];
3352 C->copy_node_notes_to(st1, old);
3353 st1 = phase->transform(st1);
3354 offset = off[nst];
3355 assert(offset >= header_size, "do not smash header");
3356 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
3357 guarantee(ins_idx != 0, "must re-insert constant store");
3358 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
3359 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
3360 set_req(--ins_idx, st1);
3361 else
3362 ins_req(ins_idx, st1);
3363 }
3364 }
3366 if (PrintCompilation && WizardMode)
3367 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
3368 old_subword, old_long, new_int, new_long);
3369 if (C->log() != NULL)
3370 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
3371 old_subword, old_long, new_int, new_long);
3373 // Clean up any remaining occurrences of zmem:
3374 remove_extra_zeroes();
3375 }
3377 // Explore forward from in(start) to find the first fully initialized
3378 // word, and return its offset. Skip groups of subword stores which
3379 // together initialize full words. If in(start) is itself part of a
3380 // fully initialized word, return the offset of in(start). If there
3381 // are no following full-word stores, or if something is fishy, return
3382 // a negative value.
3383 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
3384 int int_map = 0;
3385 intptr_t int_map_off = 0;
3386 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
3388 for (uint i = start, limit = req(); i < limit; i++) {
3389 Node* st = in(i);
3391 intptr_t st_off = get_store_offset(st, phase);
3392 if (st_off < 0) break; // return conservative answer
3394 int st_size = st->as_Store()->memory_size();
3395 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
3396 return st_off; // we found a complete word init
3397 }
3399 // update the map:
3401 intptr_t this_int_off = align_size_down(st_off, BytesPerInt);
3402 if (this_int_off != int_map_off) {
3403 // reset the map:
3404 int_map = 0;
3405 int_map_off = this_int_off;
3406 }
3408 int subword_off = st_off - this_int_off;
3409 int_map |= right_n_bits(st_size) << subword_off;
3410 if ((int_map & FULL_MAP) == FULL_MAP) {
3411 return this_int_off; // we found a complete word init
3412 }
3414 // Did this store hit or cross the word boundary?
3415 intptr_t next_int_off = align_size_down(st_off + st_size, BytesPerInt);
3416 if (next_int_off == this_int_off + BytesPerInt) {
3417 // We passed the current int, without fully initializing it.
3418 int_map_off = next_int_off;
3419 int_map >>= BytesPerInt;
3420 } else if (next_int_off > this_int_off + BytesPerInt) {
3421 // We passed the current and next int.
3422 return this_int_off + BytesPerInt;
3423 }
3424 }
3426 return -1;
3427 }
3430 // Called when the associated AllocateNode is expanded into CFG.
3431 // At this point, we may perform additional optimizations.
3432 // Linearize the stores by ascending offset, to make memory
3433 // activity as coherent as possible.
3434 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
3435 intptr_t header_size,
3436 Node* size_in_bytes,
3437 PhaseGVN* phase) {
3438 assert(!is_complete(), "not already complete");
3439 assert(stores_are_sane(phase), "");
3440 assert(allocation() != NULL, "must be present");
3442 remove_extra_zeroes();
3444 if (ReduceFieldZeroing || ReduceBulkZeroing)
3445 // reduce instruction count for common initialization patterns
3446 coalesce_subword_stores(header_size, size_in_bytes, phase);
3448 Node* zmem = zero_memory(); // initially zero memory state
3449 Node* inits = zmem; // accumulating a linearized chain of inits
3450 #ifdef ASSERT
3451 intptr_t first_offset = allocation()->minimum_header_size();
3452 intptr_t last_init_off = first_offset; // previous init offset
3453 intptr_t last_init_end = first_offset; // previous init offset+size
3454 intptr_t last_tile_end = first_offset; // previous tile offset+size
3455 #endif
3456 intptr_t zeroes_done = header_size;
3458 bool do_zeroing = true; // we might give up if inits are very sparse
3459 int big_init_gaps = 0; // how many large gaps have we seen?
3461 if (ZeroTLAB) do_zeroing = false;
3462 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
3464 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3465 Node* st = in(i);
3466 intptr_t st_off = get_store_offset(st, phase);
3467 if (st_off < 0)
3468 break; // unknown junk in the inits
3469 if (st->in(MemNode::Memory) != zmem)
3470 break; // complicated store chains somehow in list
3472 int st_size = st->as_Store()->memory_size();
3473 intptr_t next_init_off = st_off + st_size;
3475 if (do_zeroing && zeroes_done < next_init_off) {
3476 // See if this store needs a zero before it or under it.
3477 intptr_t zeroes_needed = st_off;
3479 if (st_size < BytesPerInt) {
3480 // Look for subword stores which only partially initialize words.
3481 // If we find some, we must lay down some word-level zeroes first,
3482 // underneath the subword stores.
3483 //
3484 // Examples:
3485 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
3486 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
3487 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
3488 //
3489 // Note: coalesce_subword_stores may have already done this,
3490 // if it was prompted by constant non-zero subword initializers.
3491 // But this case can still arise with non-constant stores.
3493 intptr_t next_full_store = find_next_fullword_store(i, phase);
3495 // In the examples above:
3496 // in(i) p q r s x y z
3497 // st_off 12 13 14 15 12 13 14
3498 // st_size 1 1 1 1 1 1 1
3499 // next_full_s. 12 16 16 16 16 16 16
3500 // z's_done 12 16 16 16 12 16 12
3501 // z's_needed 12 16 16 16 16 16 16
3502 // zsize 0 0 0 0 4 0 4
3503 if (next_full_store < 0) {
3504 // Conservative tack: Zero to end of current word.
3505 zeroes_needed = align_size_up(zeroes_needed, BytesPerInt);
3506 } else {
3507 // Zero to beginning of next fully initialized word.
3508 // Or, don't zero at all, if we are already in that word.
3509 assert(next_full_store >= zeroes_needed, "must go forward");
3510 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
3511 zeroes_needed = next_full_store;
3512 }
3513 }
3515 if (zeroes_needed > zeroes_done) {
3516 intptr_t zsize = zeroes_needed - zeroes_done;
3517 // Do some incremental zeroing on rawmem, in parallel with inits.
3518 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3519 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3520 zeroes_done, zeroes_needed,
3521 phase);
3522 zeroes_done = zeroes_needed;
3523 if (zsize > Matcher::init_array_short_size && ++big_init_gaps > 2)
3524 do_zeroing = false; // leave the hole, next time
3525 }
3526 }
3528 // Collect the store and move on:
3529 st->set_req(MemNode::Memory, inits);
3530 inits = st; // put it on the linearized chain
3531 set_req(i, zmem); // unhook from previous position
3533 if (zeroes_done == st_off)
3534 zeroes_done = next_init_off;
3536 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
3538 #ifdef ASSERT
3539 // Various order invariants. Weaker than stores_are_sane because
3540 // a large constant tile can be filled in by smaller non-constant stores.
3541 assert(st_off >= last_init_off, "inits do not reverse");
3542 last_init_off = st_off;
3543 const Type* val = NULL;
3544 if (st_size >= BytesPerInt &&
3545 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
3546 (int)val->basic_type() < (int)T_OBJECT) {
3547 assert(st_off >= last_tile_end, "tiles do not overlap");
3548 assert(st_off >= last_init_end, "tiles do not overwrite inits");
3549 last_tile_end = MAX2(last_tile_end, next_init_off);
3550 } else {
3551 intptr_t st_tile_end = align_size_up(next_init_off, BytesPerLong);
3552 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
3553 assert(st_off >= last_init_end, "inits do not overlap");
3554 last_init_end = next_init_off; // it's a non-tile
3555 }
3556 #endif //ASSERT
3557 }
3559 remove_extra_zeroes(); // clear out all the zmems left over
3560 add_req(inits);
3562 if (!ZeroTLAB) {
3563 // If anything remains to be zeroed, zero it all now.
3564 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3565 // if it is the last unused 4 bytes of an instance, forget about it
3566 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
3567 if (zeroes_done + BytesPerLong >= size_limit) {
3568 assert(allocation() != NULL, "");
3569 Node* klass_node = allocation()->in(AllocateNode::KlassNode);
3570 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass();
3571 if (zeroes_done == k->layout_helper())
3572 zeroes_done = size_limit;
3573 }
3574 if (zeroes_done < size_limit) {
3575 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3576 zeroes_done, size_in_bytes, phase);
3577 }
3578 }
3580 set_complete(phase);
3581 return rawmem;
3582 }
3585 #ifdef ASSERT
3586 bool InitializeNode::stores_are_sane(PhaseTransform* phase) {
3587 if (is_complete())
3588 return true; // stores could be anything at this point
3589 assert(allocation() != NULL, "must be present");
3590 intptr_t last_off = allocation()->minimum_header_size();
3591 for (uint i = InitializeNode::RawStores; i < req(); i++) {
3592 Node* st = in(i);
3593 intptr_t st_off = get_store_offset(st, phase);
3594 if (st_off < 0) continue; // ignore dead garbage
3595 if (last_off > st_off) {
3596 tty->print_cr("*** bad store offset at %d: %d > %d", i, last_off, st_off);
3597 this->dump(2);
3598 assert(false, "ascending store offsets");
3599 return false;
3600 }
3601 last_off = st_off + st->as_Store()->memory_size();
3602 }
3603 return true;
3604 }
3605 #endif //ASSERT
3610 //============================MergeMemNode=====================================
3611 //
3612 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
3613 // contributing store or call operations. Each contributor provides the memory
3614 // state for a particular "alias type" (see Compile::alias_type). For example,
3615 // if a MergeMem has an input X for alias category #6, then any memory reference
3616 // to alias category #6 may use X as its memory state input, as an exact equivalent
3617 // to using the MergeMem as a whole.
3618 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
3619 //
3620 // (Here, the <N> notation gives the index of the relevant adr_type.)
3621 //
3622 // In one special case (and more cases in the future), alias categories overlap.
3623 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
3624 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
3625 // it is exactly equivalent to that state W:
3626 // MergeMem(<Bot>: W) <==> W
3627 //
3628 // Usually, the merge has more than one input. In that case, where inputs
3629 // overlap (i.e., one is Bot), the narrower alias type determines the memory
3630 // state for that type, and the wider alias type (Bot) fills in everywhere else:
3631 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
3632 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
3633 //
3634 // A merge can take a "wide" memory state as one of its narrow inputs.
3635 // This simply means that the merge observes out only the relevant parts of
3636 // the wide input. That is, wide memory states arriving at narrow merge inputs
3637 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
3638 //
3639 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
3640 // and that memory slices "leak through":
3641 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
3642 //
3643 // But, in such a cascade, repeated memory slices can "block the leak":
3644 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
3645 //
3646 // In the last example, Y is not part of the combined memory state of the
3647 // outermost MergeMem. The system must, of course, prevent unschedulable
3648 // memory states from arising, so you can be sure that the state Y is somehow
3649 // a precursor to state Y'.
3650 //
3651 //
3652 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
3653 // of each MergeMemNode array are exactly the numerical alias indexes, including
3654 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
3655 // Compile::alias_type (and kin) produce and manage these indexes.
3656 //
3657 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
3658 // (Note that this provides quick access to the top node inside MergeMem methods,
3659 // without the need to reach out via TLS to Compile::current.)
3660 //
3661 // As a consequence of what was just described, a MergeMem that represents a full
3662 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
3663 // containing all alias categories.
3664 //
3665 // MergeMem nodes never (?) have control inputs, so in(0) is NULL.
3666 //
3667 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
3668 // a memory state for the alias type <N>, or else the top node, meaning that
3669 // there is no particular input for that alias type. Note that the length of
3670 // a MergeMem is variable, and may be extended at any time to accommodate new
3671 // memory states at larger alias indexes. When merges grow, they are of course
3672 // filled with "top" in the unused in() positions.
3673 //
3674 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
3675 // (Top was chosen because it works smoothly with passes like GCM.)
3676 //
3677 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
3678 // the type of random VM bits like TLS references.) Since it is always the
3679 // first non-Bot memory slice, some low-level loops use it to initialize an
3680 // index variable: for (i = AliasIdxRaw; i < req(); i++).
3681 //
3682 //
3683 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
3684 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
3685 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
3686 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
3687 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
3688 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
3689 //
3690 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
3691 // really that different from the other memory inputs. An abbreviation called
3692 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
3693 //
3694 //
3695 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
3696 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
3697 // that "emerges though" the base memory will be marked as excluding the alias types
3698 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
3699 //
3700 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
3701 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
3702 //
3703 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
3704 // (It is currently unimplemented.) As you can see, the resulting merge is
3705 // actually a disjoint union of memory states, rather than an overlay.
3706 //
3708 //------------------------------MergeMemNode-----------------------------------
3709 Node* MergeMemNode::make_empty_memory() {
3710 Node* empty_memory = (Node*) Compile::current()->top();
3711 assert(empty_memory->is_top(), "correct sentinel identity");
3712 return empty_memory;
3713 }
3715 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
3716 init_class_id(Class_MergeMem);
3717 // all inputs are nullified in Node::Node(int)
3718 // set_input(0, NULL); // no control input
3720 // Initialize the edges uniformly to top, for starters.
3721 Node* empty_mem = make_empty_memory();
3722 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
3723 init_req(i,empty_mem);
3724 }
3725 assert(empty_memory() == empty_mem, "");
3727 if( new_base != NULL && new_base->is_MergeMem() ) {
3728 MergeMemNode* mdef = new_base->as_MergeMem();
3729 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
3730 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
3731 mms.set_memory(mms.memory2());
3732 }
3733 assert(base_memory() == mdef->base_memory(), "");
3734 } else {
3735 set_base_memory(new_base);
3736 }
3737 }
3739 // Make a new, untransformed MergeMem with the same base as 'mem'.
3740 // If mem is itself a MergeMem, populate the result with the same edges.
3741 MergeMemNode* MergeMemNode::make(Compile* C, Node* mem) {
3742 return new(C, 1+Compile::AliasIdxRaw) MergeMemNode(mem);
3743 }
3745 //------------------------------cmp--------------------------------------------
3746 uint MergeMemNode::hash() const { return NO_HASH; }
3747 uint MergeMemNode::cmp( const Node &n ) const {
3748 return (&n == this); // Always fail except on self
3749 }
3751 //------------------------------Identity---------------------------------------
3752 Node* MergeMemNode::Identity(PhaseTransform *phase) {
3753 // Identity if this merge point does not record any interesting memory
3754 // disambiguations.
3755 Node* base_mem = base_memory();
3756 Node* empty_mem = empty_memory();
3757 if (base_mem != empty_mem) { // Memory path is not dead?
3758 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3759 Node* mem = in(i);
3760 if (mem != empty_mem && mem != base_mem) {
3761 return this; // Many memory splits; no change
3762 }
3763 }
3764 }
3765 return base_mem; // No memory splits; ID on the one true input
3766 }
3768 //------------------------------Ideal------------------------------------------
3769 // This method is invoked recursively on chains of MergeMem nodes
3770 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3771 // Remove chain'd MergeMems
3772 //
3773 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
3774 // relative to the "in(Bot)". Since we are patching both at the same time,
3775 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
3776 // but rewrite each "in(i)" relative to the new "in(Bot)".
3777 Node *progress = NULL;
3780 Node* old_base = base_memory();
3781 Node* empty_mem = empty_memory();
3782 if (old_base == empty_mem)
3783 return NULL; // Dead memory path.
3785 MergeMemNode* old_mbase;
3786 if (old_base != NULL && old_base->is_MergeMem())
3787 old_mbase = old_base->as_MergeMem();
3788 else
3789 old_mbase = NULL;
3790 Node* new_base = old_base;
3792 // simplify stacked MergeMems in base memory
3793 if (old_mbase) new_base = old_mbase->base_memory();
3795 // the base memory might contribute new slices beyond my req()
3796 if (old_mbase) grow_to_match(old_mbase);
3798 // Look carefully at the base node if it is a phi.
3799 PhiNode* phi_base;
3800 if (new_base != NULL && new_base->is_Phi())
3801 phi_base = new_base->as_Phi();
3802 else
3803 phi_base = NULL;
3805 Node* phi_reg = NULL;
3806 uint phi_len = (uint)-1;
3807 if (phi_base != NULL && !phi_base->is_copy()) {
3808 // do not examine phi if degraded to a copy
3809 phi_reg = phi_base->region();
3810 phi_len = phi_base->req();
3811 // see if the phi is unfinished
3812 for (uint i = 1; i < phi_len; i++) {
3813 if (phi_base->in(i) == NULL) {
3814 // incomplete phi; do not look at it yet!
3815 phi_reg = NULL;
3816 phi_len = (uint)-1;
3817 break;
3818 }
3819 }
3820 }
3822 // Note: We do not call verify_sparse on entry, because inputs
3823 // can normalize to the base_memory via subsume_node or similar
3824 // mechanisms. This method repairs that damage.
3826 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
3828 // Look at each slice.
3829 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3830 Node* old_in = in(i);
3831 // calculate the old memory value
3832 Node* old_mem = old_in;
3833 if (old_mem == empty_mem) old_mem = old_base;
3834 assert(old_mem == memory_at(i), "");
3836 // maybe update (reslice) the old memory value
3838 // simplify stacked MergeMems
3839 Node* new_mem = old_mem;
3840 MergeMemNode* old_mmem;
3841 if (old_mem != NULL && old_mem->is_MergeMem())
3842 old_mmem = old_mem->as_MergeMem();
3843 else
3844 old_mmem = NULL;
3845 if (old_mmem == this) {
3846 // This can happen if loops break up and safepoints disappear.
3847 // A merge of BotPtr (default) with a RawPtr memory derived from a
3848 // safepoint can be rewritten to a merge of the same BotPtr with
3849 // the BotPtr phi coming into the loop. If that phi disappears
3850 // also, we can end up with a self-loop of the mergemem.
3851 // In general, if loops degenerate and memory effects disappear,
3852 // a mergemem can be left looking at itself. This simply means
3853 // that the mergemem's default should be used, since there is
3854 // no longer any apparent effect on this slice.
3855 // Note: If a memory slice is a MergeMem cycle, it is unreachable
3856 // from start. Update the input to TOP.
3857 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
3858 }
3859 else if (old_mmem != NULL) {
3860 new_mem = old_mmem->memory_at(i);
3861 }
3862 // else preceding memory was not a MergeMem
3864 // replace equivalent phis (unfortunately, they do not GVN together)
3865 if (new_mem != NULL && new_mem != new_base &&
3866 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) {
3867 if (new_mem->is_Phi()) {
3868 PhiNode* phi_mem = new_mem->as_Phi();
3869 for (uint i = 1; i < phi_len; i++) {
3870 if (phi_base->in(i) != phi_mem->in(i)) {
3871 phi_mem = NULL;
3872 break;
3873 }
3874 }
3875 if (phi_mem != NULL) {
3876 // equivalent phi nodes; revert to the def
3877 new_mem = new_base;
3878 }
3879 }
3880 }
3882 // maybe store down a new value
3883 Node* new_in = new_mem;
3884 if (new_in == new_base) new_in = empty_mem;
3886 if (new_in != old_in) {
3887 // Warning: Do not combine this "if" with the previous "if"
3888 // A memory slice might have be be rewritten even if it is semantically
3889 // unchanged, if the base_memory value has changed.
3890 set_req(i, new_in);
3891 progress = this; // Report progress
3892 }
3893 }
3895 if (new_base != old_base) {
3896 set_req(Compile::AliasIdxBot, new_base);
3897 // Don't use set_base_memory(new_base), because we need to update du.
3898 assert(base_memory() == new_base, "");
3899 progress = this;
3900 }
3902 if( base_memory() == this ) {
3903 // a self cycle indicates this memory path is dead
3904 set_req(Compile::AliasIdxBot, empty_mem);
3905 }
3907 // Resolve external cycles by calling Ideal on a MergeMem base_memory
3908 // Recursion must occur after the self cycle check above
3909 if( base_memory()->is_MergeMem() ) {
3910 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
3911 Node *m = phase->transform(new_mbase); // Rollup any cycles
3912 if( m != NULL && (m->is_top() ||
3913 m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem) ) {
3914 // propagate rollup of dead cycle to self
3915 set_req(Compile::AliasIdxBot, empty_mem);
3916 }
3917 }
3919 if( base_memory() == empty_mem ) {
3920 progress = this;
3921 // Cut inputs during Parse phase only.
3922 // During Optimize phase a dead MergeMem node will be subsumed by Top.
3923 if( !can_reshape ) {
3924 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3925 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
3926 }
3927 }
3928 }
3930 if( !progress && base_memory()->is_Phi() && can_reshape ) {
3931 // Check if PhiNode::Ideal's "Split phis through memory merges"
3932 // transform should be attempted. Look for this->phi->this cycle.
3933 uint merge_width = req();
3934 if (merge_width > Compile::AliasIdxRaw) {
3935 PhiNode* phi = base_memory()->as_Phi();
3936 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
3937 if (phi->in(i) == this) {
3938 phase->is_IterGVN()->_worklist.push(phi);
3939 break;
3940 }
3941 }
3942 }
3943 }
3945 assert(progress || verify_sparse(), "please, no dups of base");
3946 return progress;
3947 }
3949 //-------------------------set_base_memory-------------------------------------
3950 void MergeMemNode::set_base_memory(Node *new_base) {
3951 Node* empty_mem = empty_memory();
3952 set_req(Compile::AliasIdxBot, new_base);
3953 assert(memory_at(req()) == new_base, "must set default memory");
3954 // Clear out other occurrences of new_base:
3955 if (new_base != empty_mem) {
3956 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3957 if (in(i) == new_base) set_req(i, empty_mem);
3958 }
3959 }
3960 }
3962 //------------------------------out_RegMask------------------------------------
3963 const RegMask &MergeMemNode::out_RegMask() const {
3964 return RegMask::Empty;
3965 }
3967 //------------------------------dump_spec--------------------------------------
3968 #ifndef PRODUCT
3969 void MergeMemNode::dump_spec(outputStream *st) const {
3970 st->print(" {");
3971 Node* base_mem = base_memory();
3972 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
3973 Node* mem = memory_at(i);
3974 if (mem == base_mem) { st->print(" -"); continue; }
3975 st->print( " N%d:", mem->_idx );
3976 Compile::current()->get_adr_type(i)->dump_on(st);
3977 }
3978 st->print(" }");
3979 }
3980 #endif // !PRODUCT
3983 #ifdef ASSERT
3984 static bool might_be_same(Node* a, Node* b) {
3985 if (a == b) return true;
3986 if (!(a->is_Phi() || b->is_Phi())) return false;
3987 // phis shift around during optimization
3988 return true; // pretty stupid...
3989 }
3991 // verify a narrow slice (either incoming or outgoing)
3992 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
3993 if (!VerifyAliases) return; // don't bother to verify unless requested
3994 if (is_error_reported()) return; // muzzle asserts when debugging an error
3995 if (Node::in_dump()) return; // muzzle asserts when printing
3996 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
3997 assert(n != NULL, "");
3998 // Elide intervening MergeMem's
3999 while (n->is_MergeMem()) {
4000 n = n->as_MergeMem()->memory_at(alias_idx);
4001 }
4002 Compile* C = Compile::current();
4003 const TypePtr* n_adr_type = n->adr_type();
4004 if (n == m->empty_memory()) {
4005 // Implicit copy of base_memory()
4006 } else if (n_adr_type != TypePtr::BOTTOM) {
4007 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type");
4008 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
4009 } else {
4010 // A few places like make_runtime_call "know" that VM calls are narrow,
4011 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
4012 bool expected_wide_mem = false;
4013 if (n == m->base_memory()) {
4014 expected_wide_mem = true;
4015 } else if (alias_idx == Compile::AliasIdxRaw ||
4016 n == m->memory_at(Compile::AliasIdxRaw)) {
4017 expected_wide_mem = true;
4018 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
4019 // memory can "leak through" calls on channels that
4020 // are write-once. Allow this also.
4021 expected_wide_mem = true;
4022 }
4023 assert(expected_wide_mem, "expected narrow slice replacement");
4024 }
4025 }
4026 #else // !ASSERT
4027 #define verify_memory_slice(m,i,n) (0) // PRODUCT version is no-op
4028 #endif
4031 //-----------------------------memory_at---------------------------------------
4032 Node* MergeMemNode::memory_at(uint alias_idx) const {
4033 assert(alias_idx >= Compile::AliasIdxRaw ||
4034 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0,
4035 "must avoid base_memory and AliasIdxTop");
4037 // Otherwise, it is a narrow slice.
4038 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
4039 Compile *C = Compile::current();
4040 if (is_empty_memory(n)) {
4041 // the array is sparse; empty slots are the "top" node
4042 n = base_memory();
4043 assert(Node::in_dump()
4044 || n == NULL || n->bottom_type() == Type::TOP
4045 || n->adr_type() == TypePtr::BOTTOM
4046 || n->adr_type() == TypeRawPtr::BOTTOM
4047 || Compile::current()->AliasLevel() == 0,
4048 "must be a wide memory");
4049 // AliasLevel == 0 if we are organizing the memory states manually.
4050 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
4051 } else {
4052 // make sure the stored slice is sane
4053 #ifdef ASSERT
4054 if (is_error_reported() || Node::in_dump()) {
4055 } else if (might_be_same(n, base_memory())) {
4056 // Give it a pass: It is a mostly harmless repetition of the base.
4057 // This can arise normally from node subsumption during optimization.
4058 } else {
4059 verify_memory_slice(this, alias_idx, n);
4060 }
4061 #endif
4062 }
4063 return n;
4064 }
4066 //---------------------------set_memory_at-------------------------------------
4067 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
4068 verify_memory_slice(this, alias_idx, n);
4069 Node* empty_mem = empty_memory();
4070 if (n == base_memory()) n = empty_mem; // collapse default
4071 uint need_req = alias_idx+1;
4072 if (req() < need_req) {
4073 if (n == empty_mem) return; // already the default, so do not grow me
4074 // grow the sparse array
4075 do {
4076 add_req(empty_mem);
4077 } while (req() < need_req);
4078 }
4079 set_req( alias_idx, n );
4080 }
4084 //--------------------------iteration_setup------------------------------------
4085 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
4086 if (other != NULL) {
4087 grow_to_match(other);
4088 // invariant: the finite support of mm2 is within mm->req()
4089 #ifdef ASSERT
4090 for (uint i = req(); i < other->req(); i++) {
4091 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
4092 }
4093 #endif
4094 }
4095 // Replace spurious copies of base_memory by top.
4096 Node* base_mem = base_memory();
4097 if (base_mem != NULL && !base_mem->is_top()) {
4098 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
4099 if (in(i) == base_mem)
4100 set_req(i, empty_memory());
4101 }
4102 }
4103 }
4105 //---------------------------grow_to_match-------------------------------------
4106 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
4107 Node* empty_mem = empty_memory();
4108 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
4109 // look for the finite support of the other memory
4110 for (uint i = other->req(); --i >= req(); ) {
4111 if (other->in(i) != empty_mem) {
4112 uint new_len = i+1;
4113 while (req() < new_len) add_req(empty_mem);
4114 break;
4115 }
4116 }
4117 }
4119 //---------------------------verify_sparse-------------------------------------
4120 #ifndef PRODUCT
4121 bool MergeMemNode::verify_sparse() const {
4122 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
4123 Node* base_mem = base_memory();
4124 // The following can happen in degenerate cases, since empty==top.
4125 if (is_empty_memory(base_mem)) return true;
4126 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4127 assert(in(i) != NULL, "sane slice");
4128 if (in(i) == base_mem) return false; // should have been the sentinel value!
4129 }
4130 return true;
4131 }
4133 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
4134 Node* n;
4135 n = mm->in(idx);
4136 if (mem == n) return true; // might be empty_memory()
4137 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
4138 if (mem == n) return true;
4139 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) {
4140 if (mem == n) return true;
4141 if (n == NULL) break;
4142 }
4143 return false;
4144 }
4145 #endif // !PRODUCT