1 #ifdef USE_PRAGMA_IDENT_SRC
2 #pragma ident "@(#)memnode.cpp 1.239 08/11/24 12:23:43 JVM"
3 #endif
4 /*
5 * Copyright 1997-2008 Sun Microsystems, Inc. All Rights Reserved.
6 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
7 *
8 * This code is free software; you can redistribute it and/or modify it
9 * under the terms of the GNU General Public License version 2 only, as
10 * published by the Free Software Foundation.
11 *
12 * This code is distributed in the hope that it will be useful, but WITHOUT
13 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
15 * version 2 for more details (a copy is included in the LICENSE file that
16 * accompanied this code).
17 *
18 * You should have received a copy of the GNU General Public License version
19 * 2 along with this work; if not, write to the Free Software Foundation,
20 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
21 *
22 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
23 * CA 95054 USA or visit www.sun.com if you need additional information or
24 * have any questions.
25 *
26 */
27
28 // Portions of code courtesy of Clifford Click
29
30 // Optimization - Graph Style
31
32 #include "incls/_precompiled.incl"
33 #include "incls/_memnode.cpp.incl"
34
35 //=============================================================================
36 uint MemNode::size_of() const { return sizeof(*this); }
37
38 const TypePtr *MemNode::adr_type() const {
39 Node* adr = in(Address);
40 const TypePtr* cross_check = NULL;
41 DEBUG_ONLY(cross_check = _adr_type);
42 return calculate_adr_type(adr->bottom_type(), cross_check);
43 }
44
45 #ifndef PRODUCT
46 void MemNode::dump_spec(outputStream *st) const {
47 if (in(Address) == NULL) return; // node is dead
48 #ifndef ASSERT
49 // fake the missing field
50 const TypePtr* _adr_type = NULL;
51 if (in(Address) != NULL)
52 _adr_type = in(Address)->bottom_type()->isa_ptr();
53 #endif
54 dump_adr_type(this, _adr_type, st);
55
56 Compile* C = Compile::current();
57 if( C->alias_type(_adr_type)->is_volatile() )
58 st->print(" Volatile!");
59 }
60
61 void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) {
62 st->print(" @");
63 if (adr_type == NULL) {
64 st->print("NULL");
65 } else {
66 adr_type->dump_on(st);
67 Compile* C = Compile::current();
68 Compile::AliasType* atp = NULL;
69 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type);
70 if (atp == NULL)
71 st->print(", idx=?\?;");
72 else if (atp->index() == Compile::AliasIdxBot)
73 st->print(", idx=Bot;");
74 else if (atp->index() == Compile::AliasIdxTop)
75 st->print(", idx=Top;");
76 else if (atp->index() == Compile::AliasIdxRaw)
77 st->print(", idx=Raw;");
78 else {
79 ciField* field = atp->field();
80 if (field) {
81 st->print(", name=");
82 field->print_name_on(st);
83 }
84 st->print(", idx=%d;", atp->index());
85 }
86 }
87 }
88
89 extern void print_alias_types();
90
91 #endif
92
93 //--------------------------Ideal_common---------------------------------------
94 // Look for degenerate control and memory inputs. Bypass MergeMem inputs.
95 // Unhook non-raw memories from complete (macro-expanded) initializations.
96 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
97 // If our control input is a dead region, kill all below the region
98 Node *ctl = in(MemNode::Control);
99 if (ctl && remove_dead_region(phase, can_reshape))
100 return this;
101
102 // Ignore if memory is dead, or self-loop
103 Node *mem = in(MemNode::Memory);
104 if( phase->type( mem ) == Type::TOP ) return NodeSentinel; // caller will return NULL
105 assert( mem != this, "dead loop in MemNode::Ideal" );
106
107 Node *address = in(MemNode::Address);
108 const Type *t_adr = phase->type( address );
109 if( t_adr == Type::TOP ) return NodeSentinel; // caller will return NULL
110
111 // Avoid independent memory operations
112 Node* old_mem = mem;
113
114 if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
115 InitializeNode* init = mem->in(0)->as_Initialize();
116 if (init->is_complete()) { // i.e., after macro expansion
117 const TypePtr* tp = t_adr->is_ptr();
118 uint alias_idx = phase->C->get_alias_index(tp);
119 // Free this slice from the init. It was hooked, temporarily,
120 // by GraphKit::set_output_for_allocation.
121 if (alias_idx > Compile::AliasIdxRaw) {
122 mem = init->memory(alias_idx);
123 // ...but not with the raw-pointer slice.
124 }
125 }
126 }
127
128 if (mem->is_MergeMem()) {
129 MergeMemNode* mmem = mem->as_MergeMem();
130 const TypePtr *tp = t_adr->is_ptr();
131 uint alias_idx = phase->C->get_alias_index(tp);
132 #ifdef ASSERT
133 {
134 // Check that current type is consistent with the alias index used during graph construction
135 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
136 const TypePtr *adr_t = adr_type();
137 bool consistent = adr_t == NULL || adr_t->empty() || phase->C->must_alias(adr_t, alias_idx );
138 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
139 if( !consistent && adr_t != NULL && !adr_t->empty() &&
140 tp->isa_aryptr() && tp->offset() == Type::OffsetBot &&
141 adr_t->isa_aryptr() && adr_t->offset() != Type::OffsetBot &&
142 ( adr_t->offset() == arrayOopDesc::length_offset_in_bytes() ||
143 adr_t->offset() == oopDesc::klass_offset_in_bytes() ||
144 adr_t->offset() == oopDesc::mark_offset_in_bytes() ) ) {
145 // don't assert if it is dead code.
146 consistent = true;
147 }
148 if( !consistent ) {
149 tty->print("alias_idx==%d, adr_type()==", alias_idx); if( adr_t == NULL ) { tty->print("NULL"); } else { adr_t->dump(); }
150 tty->cr();
151 print_alias_types();
152 assert(consistent, "adr_type must match alias idx");
153 }
154 }
155 #endif
156 // TypeInstPtr::NOTNULL+any is an OOP with unknown offset - generally
157 // means an array I have not precisely typed yet. Do not do any
158 // alias stuff with it any time soon.
159 const TypeInstPtr *tinst = tp->isa_instptr();
160 if( tp->base() != Type::AnyPtr &&
161 !(tinst &&
162 tinst->klass()->is_java_lang_Object() &&
163 tinst->offset() == Type::OffsetBot) ) {
164 // compress paths and change unreachable cycles to TOP
165 // If not, we can update the input infinitely along a MergeMem cycle
166 // Equivalent code in PhiNode::Ideal
167 Node* m = phase->transform(mmem);
168 // If tranformed to a MergeMem, get the desired slice
169 // Otherwise the returned node represents memory for every slice
170 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
171 // Update input if it is progress over what we have now
172 }
173 }
174
175 if (mem != old_mem) {
176 set_req(MemNode::Memory, mem);
177 return this;
178 }
179
180 // let the subclass continue analyzing...
181 return NULL;
182 }
183
184 // Helper function for proving some simple control dominations.
185 // Attempt to prove that control input 'dom' dominates (or equals) 'sub'.
186 // Already assumes that 'dom' is available at 'sub', and that 'sub'
187 // is not a constant (dominated by the method's StartNode).
188 // Used by MemNode::find_previous_store to prove that the
189 // control input of a memory operation predates (dominates)
190 // an allocation it wants to look past.
191 bool MemNode::detect_dominating_control(Node* dom, Node* sub) {
192 if (dom == NULL) return false;
193 if (dom->is_Proj()) dom = dom->in(0);
194 if (dom->is_Start()) return true; // anything inside the method
195 if (dom->is_Root()) return true; // dom 'controls' a constant
196 int cnt = 20; // detect cycle or too much effort
197 while (sub != NULL) { // walk 'sub' up the chain to 'dom'
198 if (--cnt < 0) return false; // in a cycle or too complex
199 if (sub == dom) return true;
200 if (sub->is_Start()) return false;
201 if (sub->is_Root()) return false;
202 Node* up = sub->in(0);
203 if (sub == up && sub->is_Region()) {
204 for (uint i = 1; i < sub->req(); i++) {
205 Node* in = sub->in(i);
206 if (in != NULL && !in->is_top() && in != sub) {
207 up = in; break; // take any path on the way up to 'dom'
208 }
209 }
210 }
211 if (sub == up) return false; // some kind of tight cycle
212 sub = up;
213 }
214 return false;
215 }
216
217 //---------------------detect_ptr_independence---------------------------------
218 // Used by MemNode::find_previous_store to prove that two base
219 // pointers are never equal.
220 // The pointers are accompanied by their associated allocations,
221 // if any, which have been previously discovered by the caller.
222 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
223 Node* p2, AllocateNode* a2,
224 PhaseTransform* phase) {
225 // Attempt to prove that these two pointers cannot be aliased.
226 // They may both manifestly be allocations, and they should differ.
227 // Or, if they are not both allocations, they can be distinct constants.
228 // Otherwise, one is an allocation and the other a pre-existing value.
229 if (a1 == NULL && a2 == NULL) { // neither an allocation
230 return (p1 != p2) && p1->is_Con() && p2->is_Con();
231 } else if (a1 != NULL && a2 != NULL) { // both allocations
232 return (a1 != a2);
233 } else if (a1 != NULL) { // one allocation a1
234 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.)
235 return detect_dominating_control(p2->in(0), a1->in(0));
236 } else { //(a2 != NULL) // one allocation a2
237 return detect_dominating_control(p1->in(0), a2->in(0));
238 }
239 return false;
240 }
241
242
243 // The logic for reordering loads and stores uses four steps:
244 // (a) Walk carefully past stores and initializations which we
245 // can prove are independent of this load.
246 // (b) Observe that the next memory state makes an exact match
247 // with self (load or store), and locate the relevant store.
248 // (c) Ensure that, if we were to wire self directly to the store,
249 // the optimizer would fold it up somehow.
250 // (d) Do the rewiring, and return, depending on some other part of
251 // the optimizer to fold up the load.
252 // This routine handles steps (a) and (b). Steps (c) and (d) are
253 // specific to loads and stores, so they are handled by the callers.
254 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.)
255 //
256 Node* MemNode::find_previous_store(PhaseTransform* phase) {
257 Node* ctrl = in(MemNode::Control);
258 Node* adr = in(MemNode::Address);
259 intptr_t offset = 0;
260 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
261 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase);
262
263 if (offset == Type::OffsetBot)
264 return NULL; // cannot unalias unless there are precise offsets
265
266 intptr_t size_in_bytes = memory_size();
267
268 Node* mem = in(MemNode::Memory); // start searching here...
269
270 int cnt = 50; // Cycle limiter
271 for (;;) { // While we can dance past unrelated stores...
272 if (--cnt < 0) break; // Caught in cycle or a complicated dance?
273
274 if (mem->is_Store()) {
275 Node* st_adr = mem->in(MemNode::Address);
276 intptr_t st_offset = 0;
277 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
278 if (st_base == NULL)
279 break; // inscrutable pointer
280 if (st_offset != offset && st_offset != Type::OffsetBot) {
281 const int MAX_STORE = BytesPerLong;
282 if (st_offset >= offset + size_in_bytes ||
283 st_offset <= offset - MAX_STORE ||
284 st_offset <= offset - mem->as_Store()->memory_size()) {
285 // Success: The offsets are provably independent.
286 // (You may ask, why not just test st_offset != offset and be done?
287 // The answer is that stores of different sizes can co-exist
288 // in the same sequence of RawMem effects. We sometimes initialize
289 // a whole 'tile' of array elements with a single jint or jlong.)
290 mem = mem->in(MemNode::Memory);
291 continue; // (a) advance through independent store memory
292 }
293 }
294 if (st_base != base &&
295 detect_ptr_independence(base, alloc,
296 st_base,
297 AllocateNode::Ideal_allocation(st_base, phase),
298 phase)) {
299 // Success: The bases are provably independent.
300 mem = mem->in(MemNode::Memory);
301 continue; // (a) advance through independent store memory
302 }
303
304 // (b) At this point, if the bases or offsets do not agree, we lose,
305 // since we have not managed to prove 'this' and 'mem' independent.
306 if (st_base == base && st_offset == offset) {
307 return mem; // let caller handle steps (c), (d)
308 }
309
310 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
311 InitializeNode* st_init = mem->in(0)->as_Initialize();
312 AllocateNode* st_alloc = st_init->allocation();
313 if (st_alloc == NULL)
314 break; // something degenerated
315 bool known_identical = false;
316 bool known_independent = false;
317 if (alloc == st_alloc)
318 known_identical = true;
319 else if (alloc != NULL)
320 known_independent = true;
321 else if (ctrl != NULL &&
322 detect_dominating_control(ctrl, st_alloc->in(0)))
323 known_independent = true;
324
325 if (known_independent) {
326 // The bases are provably independent: Either they are
327 // manifestly distinct allocations, or else the control
328 // of this load dominates the store's allocation.
329 int alias_idx = phase->C->get_alias_index(adr_type());
330 if (alias_idx == Compile::AliasIdxRaw) {
331 mem = st_alloc->in(TypeFunc::Memory);
332 } else {
333 mem = st_init->memory(alias_idx);
334 }
335 continue; // (a) advance through independent store memory
336 }
337
338 // (b) at this point, if we are not looking at a store initializing
339 // the same allocation we are loading from, we lose.
340 if (known_identical) {
341 // From caller, can_see_stored_value will consult find_captured_store.
342 return mem; // let caller handle steps (c), (d)
343 }
344
345 }
346
347 // Unless there is an explicit 'continue', we must bail out here,
348 // because 'mem' is an inscrutable memory state (e.g., a call).
349 break;
350 }
351
352 return NULL; // bail out
353 }
354
355 //----------------------calculate_adr_type-------------------------------------
356 // Helper function. Notices when the given type of address hits top or bottom.
357 // Also, asserts a cross-check of the type against the expected address type.
358 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
359 if (t == Type::TOP) return NULL; // does not touch memory any more?
360 #ifdef PRODUCT
361 cross_check = NULL;
362 #else
363 if (!VerifyAliases || is_error_reported() || Node::in_dump()) cross_check = NULL;
364 #endif
365 const TypePtr* tp = t->isa_ptr();
366 if (tp == NULL) {
367 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
368 return TypePtr::BOTTOM; // touches lots of memory
369 } else {
370 #ifdef ASSERT
371 // %%%% [phh] We don't check the alias index if cross_check is
372 // TypeRawPtr::BOTTOM. Needs to be investigated.
373 if (cross_check != NULL &&
374 cross_check != TypePtr::BOTTOM &&
375 cross_check != TypeRawPtr::BOTTOM) {
376 // Recheck the alias index, to see if it has changed (due to a bug).
377 Compile* C = Compile::current();
378 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
379 "must stay in the original alias category");
380 // The type of the address must be contained in the adr_type,
381 // disregarding "null"-ness.
382 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
383 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
384 assert(cross_check->meet(tp_notnull) == cross_check,
385 "real address must not escape from expected memory type");
386 }
387 #endif
388 return tp;
389 }
390 }
391
392 //------------------------adr_phi_is_loop_invariant----------------------------
393 // A helper function for Ideal_DU_postCCP to check if a Phi in a counted
394 // loop is loop invariant. Make a quick traversal of Phi and associated
395 // CastPP nodes, looking to see if they are a closed group within the loop.
396 bool MemNode::adr_phi_is_loop_invariant(Node* adr_phi, Node* cast) {
397 // The idea is that the phi-nest must boil down to only CastPP nodes
398 // with the same data. This implies that any path into the loop already
399 // includes such a CastPP, and so the original cast, whatever its input,
400 // must be covered by an equivalent cast, with an earlier control input.
401 ResourceMark rm;
402
403 // The loop entry input of the phi should be the unique dominating
404 // node for every Phi/CastPP in the loop.
405 Unique_Node_List closure;
406 closure.push(adr_phi->in(LoopNode::EntryControl));
407
408 // Add the phi node and the cast to the worklist.
409 Unique_Node_List worklist;
410 worklist.push(adr_phi);
411 if( cast != NULL ){
412 if( !cast->is_ConstraintCast() ) return false;
413 worklist.push(cast);
414 }
415
416 // Begin recursive walk of phi nodes.
417 while( worklist.size() ){
418 // Take a node off the worklist
419 Node *n = worklist.pop();
420 if( !closure.member(n) ){
421 // Add it to the closure.
422 closure.push(n);
423 // Make a sanity check to ensure we don't waste too much time here.
424 if( closure.size() > 20) return false;
425 // This node is OK if:
426 // - it is a cast of an identical value
427 // - or it is a phi node (then we add its inputs to the worklist)
428 // Otherwise, the node is not OK, and we presume the cast is not invariant
429 if( n->is_ConstraintCast() ){
430 worklist.push(n->in(1));
431 } else if( n->is_Phi() ) {
432 for( uint i = 1; i < n->req(); i++ ) {
433 worklist.push(n->in(i));
434 }
435 } else {
436 return false;
437 }
438 }
439 }
440
441 // Quit when the worklist is empty, and we've found no offending nodes.
442 return true;
443 }
444
445 //------------------------------Ideal_DU_postCCP-------------------------------
446 // Find any cast-away of null-ness and keep its control. Null cast-aways are
447 // going away in this pass and we need to make this memory op depend on the
448 // gating null check.
449
450 // I tried to leave the CastPP's in. This makes the graph more accurate in
451 // some sense; we get to keep around the knowledge that an oop is not-null
452 // after some test. Alas, the CastPP's interfere with GVN (some values are
453 // the regular oop, some are the CastPP of the oop, all merge at Phi's which
454 // cannot collapse, etc). This cost us 10% on SpecJVM, even when I removed
455 // some of the more trivial cases in the optimizer. Removing more useless
456 // Phi's started allowing Loads to illegally float above null checks. I gave
457 // up on this approach. CNC 10/20/2000
458 Node *MemNode::Ideal_DU_postCCP( PhaseCCP *ccp ) {
459 Node *ctr = in(MemNode::Control);
460 Node *mem = in(MemNode::Memory);
461 Node *adr = in(MemNode::Address);
462 Node *skipped_cast = NULL;
463 // Need a null check? Regular static accesses do not because they are
464 // from constant addresses. Array ops are gated by the range check (which
465 // always includes a NULL check). Just check field ops.
466 if( !ctr ) {
467 // Scan upwards for the highest location we can place this memory op.
468 while( true ) {
469 switch( adr->Opcode() ) {
470
471 case Op_AddP: // No change to NULL-ness, so peek thru AddP's
472 adr = adr->in(AddPNode::Base);
473 continue;
474
475 case Op_CastPP:
476 // If the CastPP is useless, just peek on through it.
477 if( ccp->type(adr) == ccp->type(adr->in(1)) ) {
478 // Remember the cast that we've peeked though. If we peek
479 // through more than one, then we end up remembering the highest
480 // one, that is, if in a loop, the one closest to the top.
481 skipped_cast = adr;
482 adr = adr->in(1);
483 continue;
484 }
485 // CastPP is going away in this pass! We need this memory op to be
486 // control-dependent on the test that is guarding the CastPP.
487 ccp->hash_delete(this);
488 set_req(MemNode::Control, adr->in(0));
489 ccp->hash_insert(this);
490 return this;
491
492 case Op_Phi:
493 // Attempt to float above a Phi to some dominating point.
494 if (adr->in(0) != NULL && adr->in(0)->is_CountedLoop()) {
495 // If we've already peeked through a Cast (which could have set the
496 // control), we can't float above a Phi, because the skipped Cast
497 // may not be loop invariant.
498 if (adr_phi_is_loop_invariant(adr, skipped_cast)) {
499 adr = adr->in(1);
500 continue;
501 }
502 }
503
504 // Intentional fallthrough!
505
506 // No obvious dominating point. The mem op is pinned below the Phi
507 // by the Phi itself. If the Phi goes away (no true value is merged)
508 // then the mem op can float, but not indefinitely. It must be pinned
509 // behind the controls leading to the Phi.
510 case Op_CheckCastPP:
511 // These usually stick around to change address type, however a
512 // useless one can be elided and we still need to pick up a control edge
513 if (adr->in(0) == NULL) {
514 // This CheckCastPP node has NO control and is likely useless. But we
515 // need check further up the ancestor chain for a control input to keep
516 // the node in place. 4959717.
517 skipped_cast = adr;
518 adr = adr->in(1);
519 continue;
520 }
521 ccp->hash_delete(this);
522 set_req(MemNode::Control, adr->in(0));
523 ccp->hash_insert(this);
524 return this;
525
526 // List of "safe" opcodes; those that implicitly block the memory
527 // op below any null check.
528 case Op_CastX2P: // no null checks on native pointers
529 case Op_Parm: // 'this' pointer is not null
530 case Op_LoadP: // Loading from within a klass
531 case Op_LoadKlass: // Loading from within a klass
532 case Op_ConP: // Loading from a klass
533 case Op_CreateEx: // Sucking up the guts of an exception oop
534 case Op_Con: // Reading from TLS
535 case Op_CMoveP: // CMoveP is pinned
536 break; // No progress
537
538 case Op_Proj: // Direct call to an allocation routine
539 case Op_SCMemProj: // Memory state from store conditional ops
540 #ifdef ASSERT
541 {
542 assert(adr->as_Proj()->_con == TypeFunc::Parms, "must be return value");
543 const Node* call = adr->in(0);
544 if (call->is_CallStaticJava()) {
545 const CallStaticJavaNode* call_java = call->as_CallStaticJava();
546 assert(call_java && call_java->method() == NULL, "must be runtime call");
547 // We further presume that this is one of
548 // new_instance_Java, new_array_Java, or
549 // the like, but do not assert for this.
550 } else if (call->is_Allocate()) {
551 // similar case to new_instance_Java, etc.
552 } else if (!call->is_CallLeaf()) {
553 // Projections from fetch_oop (OSR) are allowed as well.
554 ShouldNotReachHere();
555 }
556 }
557 #endif
558 break;
559 default:
560 ShouldNotReachHere();
561 }
562 break;
563 }
564 }
565
566 return NULL; // No progress
567 }
568
569
570 //=============================================================================
571 uint LoadNode::size_of() const { return sizeof(*this); }
572 uint LoadNode::cmp( const Node &n ) const
573 { return !Type::cmp( _type, ((LoadNode&)n)._type ); }
574 const Type *LoadNode::bottom_type() const { return _type; }
575 uint LoadNode::ideal_reg() const {
576 return Matcher::base2reg[_type->base()];
577 }
578
579 #ifndef PRODUCT
580 void LoadNode::dump_spec(outputStream *st) const {
581 MemNode::dump_spec(st);
582 if( !Verbose && !WizardMode ) {
583 // standard dump does this in Verbose and WizardMode
584 st->print(" #"); _type->dump_on(st);
585 }
586 }
587 #endif
588
589
590 //----------------------------LoadNode::make-----------------------------------
591 // Polymorphic factory method:
592 LoadNode *LoadNode::make( Compile *C, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt ) {
593 // sanity check the alias category against the created node type
594 assert(!(adr_type->isa_oopptr() &&
595 adr_type->offset() == oopDesc::klass_offset_in_bytes()),
596 "use LoadKlassNode instead");
597 assert(!(adr_type->isa_aryptr() &&
598 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
599 "use LoadRangeNode instead");
600 switch (bt) {
601 case T_BOOLEAN:
602 case T_BYTE: return new (C, 3) LoadBNode(ctl, mem, adr, adr_type, rt->is_int() );
603 case T_INT: return new (C, 3) LoadINode(ctl, mem, adr, adr_type, rt->is_int() );
604 case T_CHAR: return new (C, 3) LoadCNode(ctl, mem, adr, adr_type, rt->is_int() );
605 case T_SHORT: return new (C, 3) LoadSNode(ctl, mem, adr, adr_type, rt->is_int() );
606 case T_LONG: return new (C, 3) LoadLNode(ctl, mem, adr, adr_type, rt->is_long() );
607 case T_FLOAT: return new (C, 3) LoadFNode(ctl, mem, adr, adr_type, rt );
608 case T_DOUBLE: return new (C, 3) LoadDNode(ctl, mem, adr, adr_type, rt );
609 case T_ADDRESS: return new (C, 3) LoadPNode(ctl, mem, adr, adr_type, rt->is_ptr() );
610 case T_OBJECT: return new (C, 3) LoadPNode(ctl, mem, adr, adr_type, rt->is_oopptr());
611 }
612 ShouldNotReachHere();
613 return (LoadNode*)NULL;
614 }
615
616 LoadLNode* LoadLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt) {
617 bool require_atomic = true;
618 return new (C, 3) LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), require_atomic);
619 }
620
621
622
623
624 //------------------------------hash-------------------------------------------
625 uint LoadNode::hash() const {
626 // unroll addition of interesting fields
627 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
628 }
629
630 //---------------------------can_see_stored_value------------------------------
631 // This routine exists to make sure this set of tests is done the same
632 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
633 // will change the graph shape in a way which makes memory alive twice at the
634 // same time (uses the Oracle model of aliasing), then some
635 // LoadXNode::Identity will fold things back to the equivalence-class model
636 // of aliasing.
637 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const {
638 Node* ld_adr = in(MemNode::Address);
639
640 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
641 Compile::AliasType* atp = tp != NULL ? phase->C->alias_type(tp) : NULL;
642 if (EliminateAutoBox && atp != NULL && atp->index() >= Compile::AliasIdxRaw &&
643 atp->field() != NULL && !atp->field()->is_volatile()) {
644 uint alias_idx = atp->index();
645 bool final = atp->field()->is_final();
646 Node* result = NULL;
647 Node* current = st;
648 // Skip through chains of MemBarNodes checking the MergeMems for
649 // new states for the slice of this load. Stop once any other
650 // kind of node is encountered. Loads from final memory can skip
651 // through any kind of MemBar but normal loads shouldn't skip
652 // through MemBarAcquire since the could allow them to move out of
653 // a synchronized region.
654 while (current->is_Proj()) {
655 int opc = current->in(0)->Opcode();
656 if ((final && opc == Op_MemBarAcquire) ||
657 opc == Op_MemBarRelease || opc == Op_MemBarCPUOrder) {
658 Node* mem = current->in(0)->in(TypeFunc::Memory);
659 if (mem->is_MergeMem()) {
660 MergeMemNode* merge = mem->as_MergeMem();
661 Node* new_st = merge->memory_at(alias_idx);
662 if (new_st == merge->base_memory()) {
663 // Keep searching
664 current = merge->base_memory();
665 continue;
666 }
667 // Save the new memory state for the slice and fall through
668 // to exit.
669 result = new_st;
670 }
671 }
672 break;
673 }
674 if (result != NULL) {
675 st = result;
676 }
677 }
678
679
680 // Loop around twice in the case Load -> Initialize -> Store.
681 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
682 for (int trip = 0; trip <= 1; trip++) {
683
684 if (st->is_Store()) {
685 Node* st_adr = st->in(MemNode::Address);
686 if (!phase->eqv(st_adr, ld_adr)) {
687 // Try harder before giving up... Match raw and non-raw pointers.
688 intptr_t st_off = 0;
689 AllocateNode* alloc = AllocateNode::Ideal_allocation(st_adr, phase, st_off);
690 if (alloc == NULL) return NULL;
691 intptr_t ld_off = 0;
692 AllocateNode* allo2 = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
693 if (alloc != allo2) return NULL;
694 if (ld_off != st_off) return NULL;
695 // At this point we have proven something like this setup:
696 // A = Allocate(...)
697 // L = LoadQ(, AddP(CastPP(, A.Parm),, #Off))
698 // S = StoreQ(, AddP(, A.Parm , #Off), V)
699 // (Actually, we haven't yet proven the Q's are the same.)
700 // In other words, we are loading from a casted version of
701 // the same pointer-and-offset that we stored to.
702 // Thus, we are able to replace L by V.
703 }
704 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
705 if (store_Opcode() != st->Opcode())
706 return NULL;
707 return st->in(MemNode::ValueIn);
708 }
709
710 intptr_t offset = 0; // scratch
711
712 // A load from a freshly-created object always returns zero.
713 // (This can happen after LoadNode::Ideal resets the load's memory input
714 // to find_captured_store, which returned InitializeNode::zero_memory.)
715 if (st->is_Proj() && st->in(0)->is_Allocate() &&
716 st->in(0) == AllocateNode::Ideal_allocation(ld_adr, phase, offset) &&
717 offset >= st->in(0)->as_Allocate()->minimum_header_size()) {
718 // return a zero value for the load's basic type
719 // (This is one of the few places where a generic PhaseTransform
720 // can create new nodes. Think of it as lazily manifesting
721 // virtually pre-existing constants.)
722 return phase->zerocon(memory_type());
723 }
724
725 // A load from an initialization barrier can match a captured store.
726 if (st->is_Proj() && st->in(0)->is_Initialize()) {
727 InitializeNode* init = st->in(0)->as_Initialize();
728 AllocateNode* alloc = init->allocation();
729 if (alloc != NULL &&
730 alloc == AllocateNode::Ideal_allocation(ld_adr, phase, offset)) {
731 // examine a captured store value
732 st = init->find_captured_store(offset, memory_size(), phase);
733 if (st != NULL)
734 continue; // take one more trip around
735 }
736 }
737
738 break;
739 }
740
741 return NULL;
742 }
743
744 //------------------------------Identity---------------------------------------
745 // Loads are identity if previous store is to same address
746 Node *LoadNode::Identity( PhaseTransform *phase ) {
747 // If the previous store-maker is the right kind of Store, and the store is
748 // to the same address, then we are equal to the value stored.
749 Node* mem = in(MemNode::Memory);
750 Node* value = can_see_stored_value(mem, phase);
751 if( value ) {
752 // byte, short & char stores truncate naturally.
753 // A load has to load the truncated value which requires
754 // some sort of masking operation and that requires an
755 // Ideal call instead of an Identity call.
756 if (memory_size() < BytesPerInt) {
757 // If the input to the store does not fit with the load's result type,
758 // it must be truncated via an Ideal call.
759 if (!phase->type(value)->higher_equal(phase->type(this)))
760 return this;
761 }
762 // (This works even when value is a Con, but LoadNode::Value
763 // usually runs first, producing the singleton type of the Con.)
764 return value;
765 }
766 return this;
767 }
768
769
770 // Returns true if the AliasType refers to the field that holds the
771 // cached box array. Currently only handles the IntegerCache case.
772 static bool is_autobox_cache(Compile::AliasType* atp) {
773 if (atp != NULL && atp->field() != NULL) {
774 ciField* field = atp->field();
775 ciSymbol* klass = field->holder()->name();
776 if (field->name() == ciSymbol::cache_field_name() &&
777 field->holder()->uses_default_loader() &&
778 klass == ciSymbol::java_lang_Integer_IntegerCache()) {
779 return true;
780 }
781 }
782 return false;
783 }
784
785 // Fetch the base value in the autobox array
786 static bool fetch_autobox_base(Compile::AliasType* atp, int& cache_offset) {
787 if (atp != NULL && atp->field() != NULL) {
788 ciField* field = atp->field();
789 ciSymbol* klass = field->holder()->name();
790 if (field->name() == ciSymbol::cache_field_name() &&
791 field->holder()->uses_default_loader() &&
792 klass == ciSymbol::java_lang_Integer_IntegerCache()) {
793 assert(field->is_constant(), "what?");
794 ciObjArray* array = field->constant_value().as_object()->as_obj_array();
795 // Fetch the box object at the base of the array and get its value
796 ciInstance* box = array->obj_at(0)->as_instance();
797 ciInstanceKlass* ik = box->klass()->as_instance_klass();
798 if (ik->nof_nonstatic_fields() == 1) {
799 // This should be true nonstatic_field_at requires calling
800 // nof_nonstatic_fields so check it anyway
801 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
802 cache_offset = c.as_int();
803 }
804 return true;
805 }
806 }
807 return false;
808 }
809
810 // Returns true if the AliasType refers to the value field of an
811 // autobox object. Currently only handles Integer.
812 static bool is_autobox_object(Compile::AliasType* atp) {
813 if (atp != NULL && atp->field() != NULL) {
814 ciField* field = atp->field();
815 ciSymbol* klass = field->holder()->name();
816 if (field->name() == ciSymbol::value_name() &&
817 field->holder()->uses_default_loader() &&
818 klass == ciSymbol::java_lang_Integer()) {
819 return true;
820 }
821 }
822 return false;
823 }
824
825
826 // We're loading from an object which has autobox behaviour.
827 // If this object is result of a valueOf call we'll have a phi
828 // merging a newly allocated object and a load from the cache.
829 // We want to replace this load with the original incoming
830 // argument to the valueOf call.
831 Node* LoadNode::eliminate_autobox(PhaseGVN* phase) {
832 Node* base = in(Address)->in(AddPNode::Base);
833 if (base->is_Phi() && base->req() == 3) {
834 AllocateNode* allocation = NULL;
835 int allocation_index = -1;
836 int load_index = -1;
837 for (uint i = 1; i < base->req(); i++) {
838 allocation = AllocateNode::Ideal_allocation(base->in(i), phase);
839 if (allocation != NULL) {
840 allocation_index = i;
841 load_index = 3 - allocation_index;
842 break;
843 }
844 }
845 LoadNode* load = NULL;
846 if (allocation != NULL && base->in(load_index)->is_Load()) {
847 load = base->in(load_index)->as_Load();
848 }
849 if (load != NULL && in(Memory)->is_Phi() && in(Memory)->in(0) == base->in(0)) {
850 // Push the loads from the phi that comes from valueOf up
851 // through it to allow elimination of the loads and the recovery
852 // of the original value.
853 Node* mem_phi = in(Memory);
854 Node* offset = in(Address)->in(AddPNode::Offset);
855
856 Node* in1 = clone();
857 Node* in1_addr = in1->in(Address)->clone();
858 in1_addr->set_req(AddPNode::Base, base->in(allocation_index));
859 in1_addr->set_req(AddPNode::Address, base->in(allocation_index));
860 in1_addr->set_req(AddPNode::Offset, offset);
861 in1->set_req(0, base->in(allocation_index));
862 in1->set_req(Address, in1_addr);
863 in1->set_req(Memory, mem_phi->in(allocation_index));
864
865 Node* in2 = clone();
866 Node* in2_addr = in2->in(Address)->clone();
867 in2_addr->set_req(AddPNode::Base, base->in(load_index));
868 in2_addr->set_req(AddPNode::Address, base->in(load_index));
869 in2_addr->set_req(AddPNode::Offset, offset);
870 in2->set_req(0, base->in(load_index));
871 in2->set_req(Address, in2_addr);
872 in2->set_req(Memory, mem_phi->in(load_index));
873
874 in1_addr = phase->transform(in1_addr);
875 in1 = phase->transform(in1);
876 in2_addr = phase->transform(in2_addr);
877 in2 = phase->transform(in2);
878
879 PhiNode* result = PhiNode::make_blank(base->in(0), this);
880 result->set_req(allocation_index, in1);
881 result->set_req(load_index, in2);
882 return result;
883 }
884 } else if (base->is_Load()) {
885 // Eliminate the load of Integer.value for integers from the cache
886 // array by deriving the value from the index into the array.
887 // Capture the offset of the load and then reverse the computation.
888 Node* load_base = base->in(Address)->in(AddPNode::Base);
889 if (load_base != NULL) {
890 Compile::AliasType* atp = phase->C->alias_type(load_base->adr_type());
891 intptr_t cache_offset;
892 int shift = -1;
893 Node* cache = NULL;
894 if (is_autobox_cache(atp)) {
895 shift = exact_log2(type2aelembytes[T_OBJECT]);
896 cache = AddPNode::Ideal_base_and_offset(load_base->in(Address), phase, cache_offset);
897 }
898 if (cache != NULL && base->in(Address)->is_AddP()) {
899 Node* elements[4];
900 int count = base->in(Address)->as_AddP()->unpack_offsets(elements, ARRAY_SIZE(elements));
901 int cache_low;
902 if (count > 0 && fetch_autobox_base(atp, cache_low)) {
903 int offset = arrayOopDesc::base_offset_in_bytes(memory_type()) - (cache_low << shift);
904 // Add up all the offsets making of the address of the load
905 Node* result = elements[0];
906 for (int i = 1; i < count; i++) {
907 result = phase->transform(new (phase->C, 3) AddXNode(result, elements[i]));
908 }
909 // Remove the constant offset from the address and then
910 // remove the scaling of the offset to recover the original index.
911 result = phase->transform(new (phase->C, 3) AddXNode(result, phase->MakeConX(-offset)));
912 if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) {
913 // Peel the shift off directly but wrap it in a dummy node
914 // since Ideal can't return existing nodes
915 result = new (phase->C, 3) RShiftXNode(result->in(1), phase->intcon(0));
916 } else {
917 result = new (phase->C, 3) RShiftXNode(result, phase->intcon(shift));
918 }
919 #ifdef _LP64
920 result = new (phase->C, 2) ConvL2INode(phase->transform(result));
921 #endif
922 return result;
923 }
924 }
925 }
926 }
927 return NULL;
928 }
929
930
931 //------------------------------Ideal------------------------------------------
932 // If the load is from Field memory and the pointer is non-null, we can
933 // zero out the control input.
934 // If the offset is constant and the base is an object allocation,
935 // try to hook me up to the exact initializing store.
936 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
937 Node* p = MemNode::Ideal_common(phase, can_reshape);
938 if (p) return (p == NodeSentinel) ? NULL : p;
939
940 Node* ctrl = in(MemNode::Control);
941 Node* address = in(MemNode::Address);
942
943 // Skip up past a SafePoint control. Cannot do this for Stores because
944 // pointer stores & cardmarks must stay on the same side of a SafePoint.
945 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint &&
946 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw ) {
947 ctrl = ctrl->in(0);
948 set_req(MemNode::Control,ctrl);
949 }
950
951 // Check for useless control edge in some common special cases
952 if (in(MemNode::Control) != NULL) {
953 intptr_t ignore = 0;
954 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
955 if (base != NULL
956 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
957 && detect_dominating_control(base->in(0), phase->C->start())) {
958 // A method-invariant, non-null address (constant or 'this' argument).
959 set_req(MemNode::Control, NULL);
960 }
961 }
962
963 if (EliminateAutoBox && can_reshape && in(Address)->is_AddP()) {
964 Node* base = in(Address)->in(AddPNode::Base);
965 if (base != NULL) {
966 Compile::AliasType* atp = phase->C->alias_type(adr_type());
967 if (is_autobox_object(atp)) {
968 Node* result = eliminate_autobox(phase);
969 if (result != NULL) return result;
970 }
971 }
972 }
973
974 // Check for prior store with a different base or offset; make Load
975 // independent. Skip through any number of them. Bail out if the stores
976 // are in an endless dead cycle and report no progress. This is a key
977 // transform for Reflection. However, if after skipping through the Stores
978 // we can't then fold up against a prior store do NOT do the transform as
979 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
980 // array memory alive twice: once for the hoisted Load and again after the
981 // bypassed Store. This situation only works if EVERYBODY who does
982 // anti-dependence work knows how to bypass. I.e. we need all
983 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
984 // the alias index stuff. So instead, peek through Stores and IFF we can
985 // fold up, do so.
986 Node* prev_mem = find_previous_store(phase);
987 // Steps (a), (b): Walk past independent stores to find an exact match.
988 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) {
989 // (c) See if we can fold up on the spot, but don't fold up here.
990 // Fold-up might require truncation (for LoadB/LoadS/LoadC) or
991 // just return a prior value, which is done by Identity calls.
992 if (can_see_stored_value(prev_mem, phase)) {
993 // Make ready for step (d):
994 set_req(MemNode::Memory, prev_mem);
995 return this;
996 }
997 }
998
999 return NULL; // No further progress
1000 }
1001
1002 // Helper to recognize certain Klass fields which are invariant across
1003 // some group of array types (e.g., int[] or all T[] where T < Object).
1004 const Type*
1005 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1006 ciKlass* klass) const {
1007 if (tkls->offset() == Klass::modifier_flags_offset_in_bytes() + (int)sizeof(oopDesc)) {
1008 // The field is Klass::_modifier_flags. Return its (constant) value.
1009 // (Folds up the 2nd indirection in aClassConstant.getModifiers().)
1010 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags");
1011 return TypeInt::make(klass->modifier_flags());
1012 }
1013 if (tkls->offset() == Klass::access_flags_offset_in_bytes() + (int)sizeof(oopDesc)) {
1014 // The field is Klass::_access_flags. Return its (constant) value.
1015 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1016 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags");
1017 return TypeInt::make(klass->access_flags());
1018 }
1019 if (tkls->offset() == Klass::layout_helper_offset_in_bytes() + (int)sizeof(oopDesc)) {
1020 // The field is Klass::_layout_helper. Return its constant value if known.
1021 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper");
1022 return TypeInt::make(klass->layout_helper());
1023 }
1024
1025 // No match.
1026 return NULL;
1027 }
1028
1029 //------------------------------Value-----------------------------------------
1030 const Type *LoadNode::Value( PhaseTransform *phase ) const {
1031 // Either input is TOP ==> the result is TOP
1032 Node* mem = in(MemNode::Memory);
1033 const Type *t1 = phase->type(mem);
1034 if (t1 == Type::TOP) return Type::TOP;
1035 Node* adr = in(MemNode::Address);
1036 const TypePtr* tp = phase->type(adr)->isa_ptr();
1037 if (tp == NULL || tp->empty()) return Type::TOP;
1038 int off = tp->offset();
1039 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
1040
1041 // Try to guess loaded type from pointer type
1042 if (tp->base() == Type::AryPtr) {
1043 const Type *t = tp->is_aryptr()->elem();
1044 // Don't do this for integer types. There is only potential profit if
1045 // the element type t is lower than _type; that is, for int types, if _type is
1046 // more restrictive than t. This only happens here if one is short and the other
1047 // char (both 16 bits), and in those cases we've made an intentional decision
1048 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
1049 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
1050 //
1051 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
1052 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
1053 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
1054 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
1055 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
1056 // In fact, that could have been the original type of p1, and p1 could have
1057 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
1058 // expression (LShiftL quux 3) independently optimized to the constant 8.
1059 if ((t->isa_int() == NULL) && (t->isa_long() == NULL)
1060 && Opcode() != Op_LoadKlass) {
1061 // t might actually be lower than _type, if _type is a unique
1062 // concrete subclass of abstract class t.
1063 // Make sure the reference is not into the header, by comparing
1064 // the offset against the offset of the start of the array's data.
1065 // Different array types begin at slightly different offsets (12 vs. 16).
1066 // We choose T_BYTE as an example base type that is least restrictive
1067 // as to alignment, which will therefore produce the smallest
1068 // possible base offset.
1069 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
1070 if ((uint)off >= (uint)min_base_off) { // is the offset beyond the header?
1071 const Type* jt = t->join(_type);
1072 // In any case, do not allow the join, per se, to empty out the type.
1073 if (jt->empty() && !t->empty()) {
1074 // This can happen if a interface-typed array narrows to a class type.
1075 jt = _type;
1076 }
1077
1078 if (EliminateAutoBox) {
1079 // The pointers in the autobox arrays are always non-null
1080 Node* base = in(Address)->in(AddPNode::Base);
1081 if (base != NULL) {
1082 Compile::AliasType* atp = phase->C->alias_type(base->adr_type());
1083 if (is_autobox_cache(atp)) {
1084 return jt->join(TypePtr::NOTNULL)->is_ptr();
1085 }
1086 }
1087 }
1088 return jt;
1089 }
1090 }
1091 } else if (tp->base() == Type::InstPtr) {
1092 assert( off != Type::OffsetBot ||
1093 // arrays can be cast to Objects
1094 tp->is_oopptr()->klass()->is_java_lang_Object() ||
1095 // unsafe field access may not have a constant offset
1096 phase->C->has_unsafe_access(),
1097 "Field accesses must be precise" );
1098 // For oop loads, we expect the _type to be precise
1099 } else if (tp->base() == Type::KlassPtr) {
1100 assert( off != Type::OffsetBot ||
1101 // arrays can be cast to Objects
1102 tp->is_klassptr()->klass()->is_java_lang_Object() ||
1103 // also allow array-loading from the primary supertype
1104 // array during subtype checks
1105 Opcode() == Op_LoadKlass,
1106 "Field accesses must be precise" );
1107 // For klass/static loads, we expect the _type to be precise
1108 }
1109
1110 const TypeKlassPtr *tkls = tp->isa_klassptr();
1111 if (tkls != NULL && !StressReflectiveCode) {
1112 ciKlass* klass = tkls->klass();
1113 if (klass->is_loaded() && tkls->klass_is_exact()) {
1114 // We are loading a field from a Klass metaobject whose identity
1115 // is known at compile time (the type is "exact" or "precise").
1116 // Check for fields we know are maintained as constants by the VM.
1117 if (tkls->offset() == Klass::super_check_offset_offset_in_bytes() + (int)sizeof(oopDesc)) {
1118 // The field is Klass::_super_check_offset. Return its (constant) value.
1119 // (Folds up type checking code.)
1120 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
1121 return TypeInt::make(klass->super_check_offset());
1122 }
1123 // Compute index into primary_supers array
1124 juint depth = (tkls->offset() - (Klass::primary_supers_offset_in_bytes() + (int)sizeof(oopDesc))) / sizeof(klassOop);
1125 // Check for overflowing; use unsigned compare to handle the negative case.
1126 if( depth < ciKlass::primary_super_limit() ) {
1127 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1128 // (Folds up type checking code.)
1129 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1130 ciKlass *ss = klass->super_of_depth(depth);
1131 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1132 }
1133 const Type* aift = load_array_final_field(tkls, klass);
1134 if (aift != NULL) return aift;
1135 if (tkls->offset() == in_bytes(arrayKlass::component_mirror_offset()) + (int)sizeof(oopDesc)
1136 && klass->is_array_klass()) {
1137 // The field is arrayKlass::_component_mirror. Return its (constant) value.
1138 // (Folds up aClassConstant.getComponentType, common in Arrays.copyOf.)
1139 assert(Opcode() == Op_LoadP, "must load an oop from _component_mirror");
1140 return TypeInstPtr::make(klass->as_array_klass()->component_mirror());
1141 }
1142 if (tkls->offset() == Klass::java_mirror_offset_in_bytes() + (int)sizeof(oopDesc)) {
1143 // The field is Klass::_java_mirror. Return its (constant) value.
1144 // (Folds up the 2nd indirection in anObjConstant.getClass().)
1145 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
1146 return TypeInstPtr::make(klass->java_mirror());
1147 }
1148 }
1149
1150 // We can still check if we are loading from the primary_supers array at a
1151 // shallow enough depth. Even though the klass is not exact, entries less
1152 // than or equal to its super depth are correct.
1153 if (klass->is_loaded() ) {
1154 ciType *inner = klass->klass();
1155 while( inner->is_obj_array_klass() )
1156 inner = inner->as_obj_array_klass()->base_element_type();
1157 if( inner->is_instance_klass() &&
1158 !inner->as_instance_klass()->flags().is_interface() ) {
1159 // Compute index into primary_supers array
1160 juint depth = (tkls->offset() - (Klass::primary_supers_offset_in_bytes() + (int)sizeof(oopDesc))) / sizeof(klassOop);
1161 // Check for overflowing; use unsigned compare to handle the negative case.
1162 if( depth < ciKlass::primary_super_limit() &&
1163 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case
1164 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1165 // (Folds up type checking code.)
1166 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1167 ciKlass *ss = klass->super_of_depth(depth);
1168 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1169 }
1170 }
1171 }
1172
1173 // If the type is enough to determine that the thing is not an array,
1174 // we can give the layout_helper a positive interval type.
1175 // This will help short-circuit some reflective code.
1176 if (tkls->offset() == Klass::layout_helper_offset_in_bytes() + (int)sizeof(oopDesc)
1177 && !klass->is_array_klass() // not directly typed as an array
1178 && !klass->is_interface() // specifically not Serializable & Cloneable
1179 && !klass->is_java_lang_Object() // not the supertype of all T[]
1180 ) {
1181 // Note: When interfaces are reliable, we can narrow the interface
1182 // test to (klass != Serializable && klass != Cloneable).
1183 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
1184 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
1185 // The key property of this type is that it folds up tests
1186 // for array-ness, since it proves that the layout_helper is positive.
1187 // Thus, a generic value like the basic object layout helper works fine.
1188 return TypeInt::make(min_size, max_jint, Type::WidenMin);
1189 }
1190 }
1191
1192 // If we are loading from a freshly-allocated object, produce a zero,
1193 // if the load is provably beyond the header of the object.
1194 // (Also allow a variable load from a fresh array to produce zero.)
1195 if (ReduceFieldZeroing) {
1196 Node* value = can_see_stored_value(mem,phase);
1197 if (value != NULL && value->is_Con())
1198 return value->bottom_type();
1199 }
1200
1201 return _type;
1202 }
1203
1204 //------------------------------match_edge-------------------------------------
1205 // Do we Match on this edge index or not? Match only the address.
1206 uint LoadNode::match_edge(uint idx) const {
1207 return idx == MemNode::Address;
1208 }
1209
1210 //--------------------------LoadBNode::Ideal--------------------------------------
1211 //
1212 // If the previous store is to the same address as this load,
1213 // and the value stored was larger than a byte, replace this load
1214 // with the value stored truncated to a byte. If no truncation is
1215 // needed, the replacement is done in LoadNode::Identity().
1216 //
1217 Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1218 Node* mem = in(MemNode::Memory);
1219 Node* value = can_see_stored_value(mem,phase);
1220 if( value && !phase->type(value)->higher_equal( _type ) ) {
1221 Node *result = phase->transform( new (phase->C, 3) LShiftINode(value, phase->intcon(24)) );
1222 return new (phase->C, 3) RShiftINode(result, phase->intcon(24));
1223 }
1224 // Identity call will handle the case where truncation is not needed.
1225 return LoadNode::Ideal(phase, can_reshape);
1226 }
1227
1228 //--------------------------LoadCNode::Ideal--------------------------------------
1229 //
1230 // If the previous store is to the same address as this load,
1231 // and the value stored was larger than a char, replace this load
1232 // with the value stored truncated to a char. If no truncation is
1233 // needed, the replacement is done in LoadNode::Identity().
1234 //
1235 Node *LoadCNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1236 Node* mem = in(MemNode::Memory);
1237 Node* value = can_see_stored_value(mem,phase);
1238 if( value && !phase->type(value)->higher_equal( _type ) )
1239 return new (phase->C, 3) AndINode(value,phase->intcon(0xFFFF));
1240 // Identity call will handle the case where truncation is not needed.
1241 return LoadNode::Ideal(phase, can_reshape);
1242 }
1243
1244 //--------------------------LoadSNode::Ideal--------------------------------------
1245 //
1246 // If the previous store is to the same address as this load,
1247 // and the value stored was larger than a short, replace this load
1248 // with the value stored truncated to a short. If no truncation is
1249 // needed, the replacement is done in LoadNode::Identity().
1250 //
1251 Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1252 Node* mem = in(MemNode::Memory);
1253 Node* value = can_see_stored_value(mem,phase);
1254 if( value && !phase->type(value)->higher_equal( _type ) ) {
1255 Node *result = phase->transform( new (phase->C, 3) LShiftINode(value, phase->intcon(16)) );
1256 return new (phase->C, 3) RShiftINode(result, phase->intcon(16));
1257 }
1258 // Identity call will handle the case where truncation is not needed.
1259 return LoadNode::Ideal(phase, can_reshape);
1260 }
1261
1262 //=============================================================================
1263 //------------------------------Value------------------------------------------
1264 const Type *LoadKlassNode::Value( PhaseTransform *phase ) const {
1265 // Either input is TOP ==> the result is TOP
1266 const Type *t1 = phase->type( in(MemNode::Memory) );
1267 if (t1 == Type::TOP) return Type::TOP;
1268 Node *adr = in(MemNode::Address);
1269 const Type *t2 = phase->type( adr );
1270 if (t2 == Type::TOP) return Type::TOP;
1271 const TypePtr *tp = t2->is_ptr();
1272 if (TypePtr::above_centerline(tp->ptr()) ||
1273 tp->ptr() == TypePtr::Null) return Type::TOP;
1274
1275 // Return a more precise klass, if possible
1276 const TypeInstPtr *tinst = tp->isa_instptr();
1277 if (tinst != NULL) {
1278 ciInstanceKlass* ik = tinst->klass()->as_instance_klass();
1279 int offset = tinst->offset();
1280 if (ik == phase->C->env()->Class_klass()
1281 && (offset == java_lang_Class::klass_offset_in_bytes() ||
1282 offset == java_lang_Class::array_klass_offset_in_bytes())) {
1283 // We are loading a special hidden field from a Class mirror object,
1284 // the field which points to the VM's Klass metaobject.
1285 ciType* t = tinst->java_mirror_type();
1286 // java_mirror_type returns non-null for compile-time Class constants.
1287 if (t != NULL) {
1288 // constant oop => constant klass
1289 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
1290 return TypeKlassPtr::make(ciArrayKlass::make(t));
1291 }
1292 if (!t->is_klass()) {
1293 // a primitive Class (e.g., int.class) has NULL for a klass field
1294 return TypePtr::NULL_PTR;
1295 }
1296 // (Folds up the 1st indirection in aClassConstant.getModifiers().)
1297 return TypeKlassPtr::make(t->as_klass());
1298 }
1299 // non-constant mirror, so we can't tell what's going on
1300 }
1301 if( !ik->is_loaded() )
1302 return _type; // Bail out if not loaded
1303 if (offset == oopDesc::klass_offset_in_bytes()) {
1304 if (tinst->klass_is_exact()) {
1305 return TypeKlassPtr::make(ik);
1306 }
1307 // See if we can become precise: no subklasses and no interface
1308 // (Note: We need to support verified interfaces.)
1309 if (!ik->is_interface() && !ik->has_subklass()) {
1310 //assert(!UseExactTypes, "this code should be useless with exact types");
1311 // Add a dependence; if any subclass added we need to recompile
1312 if (!ik->is_final()) {
1313 // %%% should use stronger assert_unique_concrete_subtype instead
1314 phase->C->dependencies()->assert_leaf_type(ik);
1315 }
1316 // Return precise klass
1317 return TypeKlassPtr::make(ik);
1318 }
1319
1320 // Return root of possible klass
1321 return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/);
1322 }
1323 }
1324
1325 // Check for loading klass from an array
1326 const TypeAryPtr *tary = tp->isa_aryptr();
1327 if( tary != NULL ) {
1328 ciKlass *tary_klass = tary->klass();
1329 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP
1330 && tary->offset() == oopDesc::klass_offset_in_bytes()) {
1331 if (tary->klass_is_exact()) {
1332 return TypeKlassPtr::make(tary_klass);
1333 }
1334 ciArrayKlass *ak = tary->klass()->as_array_klass();
1335 // If the klass is an object array, we defer the question to the
1336 // array component klass.
1337 if( ak->is_obj_array_klass() ) {
1338 assert( ak->is_loaded(), "" );
1339 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass();
1340 if( base_k->is_loaded() && base_k->is_instance_klass() ) {
1341 ciInstanceKlass* ik = base_k->as_instance_klass();
1342 // See if we can become precise: no subklasses and no interface
1343 if (!ik->is_interface() && !ik->has_subklass()) {
1344 //assert(!UseExactTypes, "this code should be useless with exact types");
1345 // Add a dependence; if any subclass added we need to recompile
1346 if (!ik->is_final()) {
1347 phase->C->dependencies()->assert_leaf_type(ik);
1348 }
1349 // Return precise array klass
1350 return TypeKlassPtr::make(ak);
1351 }
1352 }
1353 return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/);
1354 } else { // Found a type-array?
1355 //assert(!UseExactTypes, "this code should be useless with exact types");
1356 assert( ak->is_type_array_klass(), "" );
1357 return TypeKlassPtr::make(ak); // These are always precise
1358 }
1359 }
1360 }
1361
1362 // Check for loading klass from an array klass
1363 const TypeKlassPtr *tkls = tp->isa_klassptr();
1364 if (tkls != NULL && !StressReflectiveCode) {
1365 ciKlass* klass = tkls->klass();
1366 if( !klass->is_loaded() )
1367 return _type; // Bail out if not loaded
1368 if( klass->is_obj_array_klass() &&
1369 (uint)tkls->offset() == objArrayKlass::element_klass_offset_in_bytes() + sizeof(oopDesc)) {
1370 ciKlass* elem = klass->as_obj_array_klass()->element_klass();
1371 // // Always returning precise element type is incorrect,
1372 // // e.g., element type could be object and array may contain strings
1373 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
1374
1375 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
1376 // according to the element type's subclassing.
1377 return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/);
1378 }
1379 if( klass->is_instance_klass() && tkls->klass_is_exact() &&
1380 (uint)tkls->offset() == Klass::super_offset_in_bytes() + sizeof(oopDesc)) {
1381 ciKlass* sup = klass->as_instance_klass()->super();
1382 // The field is Klass::_super. Return its (constant) value.
1383 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
1384 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR;
1385 }
1386 }
1387
1388 // Bailout case
1389 return LoadNode::Value(phase);
1390 }
1391
1392 //------------------------------Identity---------------------------------------
1393 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
1394 // Also feed through the klass in Allocate(...klass...)._klass.
1395 Node* LoadKlassNode::Identity( PhaseTransform *phase ) {
1396 Node* x = LoadNode::Identity(phase);
1397 if (x != this) return x;
1398
1399 // Take apart the address into an oop and and offset.
1400 // Return 'this' if we cannot.
1401 Node* adr = in(MemNode::Address);
1402 intptr_t offset = 0;
1403 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
1404 if (base == NULL) return this;
1405 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
1406 if (toop == NULL) return this;
1407
1408 // We can fetch the klass directly through an AllocateNode.
1409 // This works even if the klass is not constant (clone or newArray).
1410 if (offset == oopDesc::klass_offset_in_bytes()) {
1411 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
1412 if (allocated_klass != NULL) {
1413 return allocated_klass;
1414 }
1415 }
1416
1417 // Simplify k.java_mirror.as_klass to plain k, where k is a klassOop.
1418 // Simplify ak.component_mirror.array_klass to plain ak, ak an arrayKlass.
1419 // See inline_native_Class_query for occurrences of these patterns.
1420 // Java Example: x.getClass().isAssignableFrom(y)
1421 // Java Example: Array.newInstance(x.getClass().getComponentType(), n)
1422 //
1423 // This improves reflective code, often making the Class
1424 // mirror go completely dead. (Current exception: Class
1425 // mirrors may appear in debug info, but we could clean them out by
1426 // introducing a new debug info operator for klassOop.java_mirror).
1427 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass()
1428 && (offset == java_lang_Class::klass_offset_in_bytes() ||
1429 offset == java_lang_Class::array_klass_offset_in_bytes())) {
1430 // We are loading a special hidden field from a Class mirror,
1431 // the field which points to its Klass or arrayKlass metaobject.
1432 if (base->is_Load()) {
1433 Node* adr2 = base->in(MemNode::Address);
1434 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
1435 if (tkls != NULL && !tkls->empty()
1436 && (tkls->klass()->is_instance_klass() ||
1437 tkls->klass()->is_array_klass())
1438 && adr2->is_AddP()
1439 ) {
1440 int mirror_field = Klass::java_mirror_offset_in_bytes();
1441 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
1442 mirror_field = in_bytes(arrayKlass::component_mirror_offset());
1443 }
1444 if (tkls->offset() == mirror_field + (int)sizeof(oopDesc)) {
1445 return adr2->in(AddPNode::Base);
1446 }
1447 }
1448 }
1449 }
1450
1451 return this;
1452 }
1453
1454 //------------------------------Value-----------------------------------------
1455 const Type *LoadRangeNode::Value( PhaseTransform *phase ) const {
1456 // Either input is TOP ==> the result is TOP
1457 const Type *t1 = phase->type( in(MemNode::Memory) );
1458 if( t1 == Type::TOP ) return Type::TOP;
1459 Node *adr = in(MemNode::Address);
1460 const Type *t2 = phase->type( adr );
1461 if( t2 == Type::TOP ) return Type::TOP;
1462 const TypePtr *tp = t2->is_ptr();
1463 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
1464 const TypeAryPtr *tap = tp->isa_aryptr();
1465 if( !tap ) return _type;
1466 return tap->size();
1467 }
1468
1469 //------------------------------Identity---------------------------------------
1470 // Feed through the length in AllocateArray(...length...)._length.
1471 Node* LoadRangeNode::Identity( PhaseTransform *phase ) {
1472 Node* x = LoadINode::Identity(phase);
1473 if (x != this) return x;
1474
1475 // Take apart the address into an oop and and offset.
1476 // Return 'this' if we cannot.
1477 Node* adr = in(MemNode::Address);
1478 intptr_t offset = 0;
1479 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
1480 if (base == NULL) return this;
1481 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
1482 if (tary == NULL) return this;
1483
1484 // We can fetch the length directly through an AllocateArrayNode.
1485 // This works even if the length is not constant (clone or newArray).
1486 if (offset == arrayOopDesc::length_offset_in_bytes()) {
1487 Node* allocated_length = AllocateArrayNode::Ideal_length(base, phase);
1488 if (allocated_length != NULL) {
1489 return allocated_length;
1490 }
1491 }
1492
1493 return this;
1494
1495 }
1496 //=============================================================================
1497 //---------------------------StoreNode::make-----------------------------------
1498 // Polymorphic factory method:
1499 StoreNode* StoreNode::make( Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt ) {
1500 switch (bt) {
1501 case T_BOOLEAN:
1502 case T_BYTE: return new (C, 4) StoreBNode(ctl, mem, adr, adr_type, val);
1503 case T_INT: return new (C, 4) StoreINode(ctl, mem, adr, adr_type, val);
1504 case T_CHAR:
1505 case T_SHORT: return new (C, 4) StoreCNode(ctl, mem, adr, adr_type, val);
1506 case T_LONG: return new (C, 4) StoreLNode(ctl, mem, adr, adr_type, val);
1507 case T_FLOAT: return new (C, 4) StoreFNode(ctl, mem, adr, adr_type, val);
1508 case T_DOUBLE: return new (C, 4) StoreDNode(ctl, mem, adr, adr_type, val);
1509 case T_ADDRESS:
1510 case T_OBJECT: return new (C, 4) StorePNode(ctl, mem, adr, adr_type, val);
1511 }
1512 ShouldNotReachHere();
1513 return (StoreNode*)NULL;
1514 }
1515
1516 StoreLNode* StoreLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val) {
1517 bool require_atomic = true;
1518 return new (C, 4) StoreLNode(ctl, mem, adr, adr_type, val, require_atomic);
1519 }
1520
1521
1522 //--------------------------bottom_type----------------------------------------
1523 const Type *StoreNode::bottom_type() const {
1524 return Type::MEMORY;
1525 }
1526
1527 //------------------------------hash-------------------------------------------
1528 uint StoreNode::hash() const {
1529 // unroll addition of interesting fields
1530 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
1531
1532 // Since they are not commoned, do not hash them:
1533 return NO_HASH;
1534 }
1535
1536 //------------------------------Ideal------------------------------------------
1537 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
1538 // When a store immediately follows a relevant allocation/initialization,
1539 // try to capture it into the initialization, or hoist it above.
1540 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1541 Node* p = MemNode::Ideal_common(phase, can_reshape);
1542 if (p) return (p == NodeSentinel) ? NULL : p;
1543
1544 Node* mem = in(MemNode::Memory);
1545 Node* address = in(MemNode::Address);
1546
1547 // Back-to-back stores to same address? Fold em up.
1548 // Generally unsafe if I have intervening uses...
1549 if (mem->is_Store() && phase->eqv_uncast(mem->in(MemNode::Address), address)) {
1550 // Looking at a dead closed cycle of memory?
1551 assert(mem != mem->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
1552
1553 assert(Opcode() == mem->Opcode() ||
1554 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw,
1555 "no mismatched stores, except on raw memory");
1556
1557 if (mem->outcnt() == 1 && // check for intervening uses
1558 mem->as_Store()->memory_size() <= this->memory_size()) {
1559 // If anybody other than 'this' uses 'mem', we cannot fold 'mem' away.
1560 // For example, 'mem' might be the final state at a conditional return.
1561 // Or, 'mem' might be used by some node which is live at the same time
1562 // 'this' is live, which might be unschedulable. So, require exactly
1563 // ONE user, the 'this' store, until such time as we clone 'mem' for
1564 // each of 'mem's uses (thus making the exactly-1-user-rule hold true).
1565 if (can_reshape) { // (%%% is this an anachronism?)
1566 set_req_X(MemNode::Memory, mem->in(MemNode::Memory),
1567 phase->is_IterGVN());
1568 } else {
1569 // It's OK to do this in the parser, since DU info is always accurate,
1570 // and the parser always refers to nodes via SafePointNode maps.
1571 set_req(MemNode::Memory, mem->in(MemNode::Memory));
1572 }
1573 return this;
1574 }
1575 }
1576
1577 // Capture an unaliased, unconditional, simple store into an initializer.
1578 // Or, if it is independent of the allocation, hoist it above the allocation.
1579 if (ReduceFieldZeroing && /*can_reshape &&*/
1580 mem->is_Proj() && mem->in(0)->is_Initialize()) {
1581 InitializeNode* init = mem->in(0)->as_Initialize();
1582 intptr_t offset = init->can_capture_store(this, phase);
1583 if (offset > 0) {
1584 Node* moved = init->capture_store(this, offset, phase);
1585 // If the InitializeNode captured me, it made a raw copy of me,
1586 // and I need to disappear.
1587 if (moved != NULL) {
1588 // %%% hack to ensure that Ideal returns a new node:
1589 mem = MergeMemNode::make(phase->C, mem);
1590 return mem; // fold me away
1591 }
1592 }
1593 }
1594
1595 return NULL; // No further progress
1596 }
1597
1598 //------------------------------Value-----------------------------------------
1599 const Type *StoreNode::Value( PhaseTransform *phase ) const {
1600 // Either input is TOP ==> the result is TOP
1601 const Type *t1 = phase->type( in(MemNode::Memory) );
1602 if( t1 == Type::TOP ) return Type::TOP;
1603 const Type *t2 = phase->type( in(MemNode::Address) );
1604 if( t2 == Type::TOP ) return Type::TOP;
1605 const Type *t3 = phase->type( in(MemNode::ValueIn) );
1606 if( t3 == Type::TOP ) return Type::TOP;
1607 return Type::MEMORY;
1608 }
1609
1610 //------------------------------Identity---------------------------------------
1611 // Remove redundant stores:
1612 // Store(m, p, Load(m, p)) changes to m.
1613 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
1614 Node *StoreNode::Identity( PhaseTransform *phase ) {
1615 Node* mem = in(MemNode::Memory);
1616 Node* adr = in(MemNode::Address);
1617 Node* val = in(MemNode::ValueIn);
1618
1619 // Load then Store? Then the Store is useless
1620 if (val->is_Load() &&
1621 phase->eqv_uncast( val->in(MemNode::Address), adr ) &&
1622 phase->eqv_uncast( val->in(MemNode::Memory ), mem ) &&
1623 val->as_Load()->store_Opcode() == Opcode()) {
1624 return mem;
1625 }
1626
1627 // Two stores in a row of the same value?
1628 if (mem->is_Store() &&
1629 phase->eqv_uncast( mem->in(MemNode::Address), adr ) &&
1630 phase->eqv_uncast( mem->in(MemNode::ValueIn), val ) &&
1631 mem->Opcode() == Opcode()) {
1632 return mem;
1633 }
1634
1635 // Store of zero anywhere into a freshly-allocated object?
1636 // Then the store is useless.
1637 // (It must already have been captured by the InitializeNode.)
1638 if (ReduceFieldZeroing && phase->type(val)->is_zero_type()) {
1639 // a newly allocated object is already all-zeroes everywhere
1640 if (mem->is_Proj() && mem->in(0)->is_Allocate()) {
1641 return mem;
1642 }
1643
1644 // the store may also apply to zero-bits in an earlier object
1645 Node* prev_mem = find_previous_store(phase);
1646 // Steps (a), (b): Walk past independent stores to find an exact match.
1647 if (prev_mem != NULL) {
1648 Node* prev_val = can_see_stored_value(prev_mem, phase);
1649 if (prev_val != NULL && phase->eqv(prev_val, val)) {
1650 // prev_val and val might differ by a cast; it would be good
1651 // to keep the more informative of the two.
1652 return mem;
1653 }
1654 }
1655 }
1656
1657 return this;
1658 }
1659
1660 //------------------------------match_edge-------------------------------------
1661 // Do we Match on this edge index or not? Match only memory & value
1662 uint StoreNode::match_edge(uint idx) const {
1663 return idx == MemNode::Address || idx == MemNode::ValueIn;
1664 }
1665
1666 //------------------------------cmp--------------------------------------------
1667 // Do not common stores up together. They generally have to be split
1668 // back up anyways, so do not bother.
1669 uint StoreNode::cmp( const Node &n ) const {
1670 return (&n == this); // Always fail except on self
1671 }
1672
1673 //------------------------------Ideal_masked_input-----------------------------
1674 // Check for a useless mask before a partial-word store
1675 // (StoreB ... (AndI valIn conIa) )
1676 // If (conIa & mask == mask) this simplifies to
1677 // (StoreB ... (valIn) )
1678 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
1679 Node *val = in(MemNode::ValueIn);
1680 if( val->Opcode() == Op_AndI ) {
1681 const TypeInt *t = phase->type( val->in(2) )->isa_int();
1682 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
1683 set_req(MemNode::ValueIn, val->in(1));
1684 return this;
1685 }
1686 }
1687 return NULL;
1688 }
1689
1690
1691 //------------------------------Ideal_sign_extended_input----------------------
1692 // Check for useless sign-extension before a partial-word store
1693 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) )
1694 // If (conIL == conIR && conIR <= num_bits) this simplifies to
1695 // (StoreB ... (valIn) )
1696 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) {
1697 Node *val = in(MemNode::ValueIn);
1698 if( val->Opcode() == Op_RShiftI ) {
1699 const TypeInt *t = phase->type( val->in(2) )->isa_int();
1700 if( t && t->is_con() && (t->get_con() <= num_bits) ) {
1701 Node *shl = val->in(1);
1702 if( shl->Opcode() == Op_LShiftI ) {
1703 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int();
1704 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) {
1705 set_req(MemNode::ValueIn, shl->in(1));
1706 return this;
1707 }
1708 }
1709 }
1710 }
1711 return NULL;
1712 }
1713
1714 //------------------------------value_never_loaded-----------------------------------
1715 // Determine whether there are any possible loads of the value stored.
1716 // For simplicity, we actually check if there are any loads from the
1717 // address stored to, not just for loads of the value stored by this node.
1718 //
1719 bool StoreNode::value_never_loaded( PhaseTransform *phase) const {
1720 Node *adr = in(Address);
1721 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
1722 if (adr_oop == NULL)
1723 return false;
1724 if (!adr_oop->is_instance())
1725 return false; // if not a distinct instance, there may be aliases of the address
1726 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
1727 Node *use = adr->fast_out(i);
1728 int opc = use->Opcode();
1729 if (use->is_Load() || use->is_LoadStore()) {
1730 return false;
1731 }
1732 }
1733 return true;
1734 }
1735
1736 //=============================================================================
1737 //------------------------------Ideal------------------------------------------
1738 // If the store is from an AND mask that leaves the low bits untouched, then
1739 // we can skip the AND operation. If the store is from a sign-extension
1740 // (a left shift, then right shift) we can skip both.
1741 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
1742 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
1743 if( progress != NULL ) return progress;
1744
1745 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
1746 if( progress != NULL ) return progress;
1747
1748 // Finally check the default case
1749 return StoreNode::Ideal(phase, can_reshape);
1750 }
1751
1752 //=============================================================================
1753 //------------------------------Ideal------------------------------------------
1754 // If the store is from an AND mask that leaves the low bits untouched, then
1755 // we can skip the AND operation
1756 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
1757 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
1758 if( progress != NULL ) return progress;
1759
1760 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
1761 if( progress != NULL ) return progress;
1762
1763 // Finally check the default case
1764 return StoreNode::Ideal(phase, can_reshape);
1765 }
1766
1767 //=============================================================================
1768 //------------------------------Identity---------------------------------------
1769 Node *StoreCMNode::Identity( PhaseTransform *phase ) {
1770 // No need to card mark when storing a null ptr
1771 Node* my_store = in(MemNode::OopStore);
1772 if (my_store->is_Store()) {
1773 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) );
1774 if( t1 == TypePtr::NULL_PTR ) {
1775 return in(MemNode::Memory);
1776 }
1777 }
1778 return this;
1779 }
1780
1781 //------------------------------Value-----------------------------------------
1782 const Type *StoreCMNode::Value( PhaseTransform *phase ) const {
1783 // Either input is TOP ==> the result is TOP
1784 const Type *t = phase->type( in(MemNode::Memory) );
1785 if( t == Type::TOP ) return Type::TOP;
1786 t = phase->type( in(MemNode::Address) );
1787 if( t == Type::TOP ) return Type::TOP;
1788 t = phase->type( in(MemNode::ValueIn) );
1789 if( t == Type::TOP ) return Type::TOP;
1790 // If extra input is TOP ==> the result is TOP
1791 t = phase->type( in(MemNode::OopStore) );
1792 if( t == Type::TOP ) return Type::TOP;
1793
1794 return StoreNode::Value( phase );
1795 }
1796
1797
1798 //=============================================================================
1799 //----------------------------------SCMemProjNode------------------------------
1800 const Type * SCMemProjNode::Value( PhaseTransform *phase ) const
1801 {
1802 return bottom_type();
1803 }
1804
1805 //=============================================================================
1806 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : Node(5) {
1807 init_req(MemNode::Control, c );
1808 init_req(MemNode::Memory , mem);
1809 init_req(MemNode::Address, adr);
1810 init_req(MemNode::ValueIn, val);
1811 init_req( ExpectedIn, ex );
1812 init_class_id(Class_LoadStore);
1813
1814 }
1815
1816 //=============================================================================
1817 //-------------------------------adr_type--------------------------------------
1818 // Do we Match on this edge index or not? Do not match memory
1819 const TypePtr* ClearArrayNode::adr_type() const {
1820 Node *adr = in(3);
1821 return MemNode::calculate_adr_type(adr->bottom_type());
1822 }
1823
1824 //------------------------------match_edge-------------------------------------
1825 // Do we Match on this edge index or not? Do not match memory
1826 uint ClearArrayNode::match_edge(uint idx) const {
1827 return idx > 1;
1828 }
1829
1830 //------------------------------Identity---------------------------------------
1831 // Clearing a zero length array does nothing
1832 Node *ClearArrayNode::Identity( PhaseTransform *phase ) {
1833 return phase->type(in(2))->higher_equal(TypeInt::ZERO) ? in(1) : this;
1834 }
1835
1836 //------------------------------Idealize---------------------------------------
1837 // Clearing a short array is faster with stores
1838 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape){
1839 const int unit = BytesPerLong;
1840 const TypeX* t = phase->type(in(2))->isa_intptr_t();
1841 if (!t) return NULL;
1842 if (!t->is_con()) return NULL;
1843 intptr_t raw_count = t->get_con();
1844 intptr_t size = raw_count;
1845 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
1846 // Clearing nothing uses the Identity call.
1847 // Negative clears are possible on dead ClearArrays
1848 // (see jck test stmt114.stmt11402.val).
1849 if (size <= 0 || size % unit != 0) return NULL;
1850 intptr_t count = size / unit;
1851 // Length too long; use fast hardware clear
1852 if (size > Matcher::init_array_short_size) return NULL;
1853 Node *mem = in(1);
1854 if( phase->type(mem)==Type::TOP ) return NULL;
1855 Node *adr = in(3);
1856 const Type* at = phase->type(adr);
1857 if( at==Type::TOP ) return NULL;
1858 const TypePtr* atp = at->isa_ptr();
1859 // adjust atp to be the correct array element address type
1860 if (atp == NULL) atp = TypePtr::BOTTOM;
1861 else atp = atp->add_offset(Type::OffsetBot);
1862 // Get base for derived pointer purposes
1863 if( adr->Opcode() != Op_AddP ) Unimplemented();
1864 Node *base = adr->in(1);
1865
1866 Node *zero = phase->makecon(TypeLong::ZERO);
1867 Node *off = phase->MakeConX(BytesPerLong);
1868 mem = new (phase->C, 4) StoreLNode(in(0),mem,adr,atp,zero);
1869 count--;
1870 while( count-- ) {
1871 mem = phase->transform(mem);
1872 adr = phase->transform(new (phase->C, 4) AddPNode(base,adr,off));
1873 mem = new (phase->C, 4) StoreLNode(in(0),mem,adr,atp,zero);
1874 }
1875 return mem;
1876 }
1877
1878 //----------------------------clear_memory-------------------------------------
1879 // Generate code to initialize object storage to zero.
1880 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
1881 intptr_t start_offset,
1882 Node* end_offset,
1883 PhaseGVN* phase) {
1884 Compile* C = phase->C;
1885 intptr_t offset = start_offset;
1886
1887 int unit = BytesPerLong;
1888 if ((offset % unit) != 0) {
1889 Node* adr = new (C, 4) AddPNode(dest, dest, phase->MakeConX(offset));
1890 adr = phase->transform(adr);
1891 const TypePtr* atp = TypeRawPtr::BOTTOM;
1892 mem = StoreNode::make(C, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT);
1893 mem = phase->transform(mem);
1894 offset += BytesPerInt;
1895 }
1896 assert((offset % unit) == 0, "");
1897
1898 // Initialize the remaining stuff, if any, with a ClearArray.
1899 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase);
1900 }
1901
1902 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
1903 Node* start_offset,
1904 Node* end_offset,
1905 PhaseGVN* phase) {
1906 Compile* C = phase->C;
1907 int unit = BytesPerLong;
1908 Node* zbase = start_offset;
1909 Node* zend = end_offset;
1910
1911 // Scale to the unit required by the CPU:
1912 if (!Matcher::init_array_count_is_in_bytes) {
1913 Node* shift = phase->intcon(exact_log2(unit));
1914 zbase = phase->transform( new(C,3) URShiftXNode(zbase, shift) );
1915 zend = phase->transform( new(C,3) URShiftXNode(zend, shift) );
1916 }
1917
1918 Node* zsize = phase->transform( new(C,3) SubXNode(zend, zbase) );
1919 Node* zinit = phase->zerocon((unit == BytesPerLong) ? T_LONG : T_INT);
1920
1921 // Bulk clear double-words
1922 Node* adr = phase->transform( new(C,4) AddPNode(dest, dest, start_offset) );
1923 mem = new (C, 4) ClearArrayNode(ctl, mem, zsize, adr);
1924 return phase->transform(mem);
1925 }
1926
1927 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
1928 intptr_t start_offset,
1929 intptr_t end_offset,
1930 PhaseGVN* phase) {
1931 Compile* C = phase->C;
1932 assert((end_offset % BytesPerInt) == 0, "odd end offset");
1933 intptr_t done_offset = end_offset;
1934 if ((done_offset % BytesPerLong) != 0) {
1935 done_offset -= BytesPerInt;
1936 }
1937 if (done_offset > start_offset) {
1938 mem = clear_memory(ctl, mem, dest,
1939 start_offset, phase->MakeConX(done_offset), phase);
1940 }
1941 if (done_offset < end_offset) { // emit the final 32-bit store
1942 Node* adr = new (C, 4) AddPNode(dest, dest, phase->MakeConX(done_offset));
1943 adr = phase->transform(adr);
1944 const TypePtr* atp = TypeRawPtr::BOTTOM;
1945 mem = StoreNode::make(C, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT);
1946 mem = phase->transform(mem);
1947 done_offset += BytesPerInt;
1948 }
1949 assert(done_offset == end_offset, "");
1950 return mem;
1951 }
1952
1953 //=============================================================================
1954 // Do we match on this edge? No memory edges
1955 uint StrCompNode::match_edge(uint idx) const {
1956 return idx == 5 || idx == 6;
1957 }
1958
1959 //------------------------------Ideal------------------------------------------
1960 // Return a node which is more "ideal" than the current node. Strip out
1961 // control copies
1962 Node *StrCompNode::Ideal(PhaseGVN *phase, bool can_reshape){
1963 return remove_dead_region(phase, can_reshape) ? this : NULL;
1964 }
1965
1966
1967 //=============================================================================
1968 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
1969 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)),
1970 _adr_type(C->get_adr_type(alias_idx))
1971 {
1972 init_class_id(Class_MemBar);
1973 Node* top = C->top();
1974 init_req(TypeFunc::I_O,top);
1975 init_req(TypeFunc::FramePtr,top);
1976 init_req(TypeFunc::ReturnAdr,top);
1977 if (precedent != NULL)
1978 init_req(TypeFunc::Parms, precedent);
1979 }
1980
1981 //------------------------------cmp--------------------------------------------
1982 uint MemBarNode::hash() const { return NO_HASH; }
1983 uint MemBarNode::cmp( const Node &n ) const {
1984 return (&n == this); // Always fail except on self
1985 }
1986
1987 //------------------------------make-------------------------------------------
1988 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
1989 int len = Precedent + (pn == NULL? 0: 1);
1990 switch (opcode) {
1991 case Op_MemBarAcquire: return new(C, len) MemBarAcquireNode(C, atp, pn);
1992 case Op_MemBarRelease: return new(C, len) MemBarReleaseNode(C, atp, pn);
1993 case Op_MemBarVolatile: return new(C, len) MemBarVolatileNode(C, atp, pn);
1994 case Op_MemBarCPUOrder: return new(C, len) MemBarCPUOrderNode(C, atp, pn);
1995 case Op_Initialize: return new(C, len) InitializeNode(C, atp, pn);
1996 default: ShouldNotReachHere(); return NULL;
1997 }
1998 }
1999
2000 //------------------------------Ideal------------------------------------------
2001 // Return a node which is more "ideal" than the current node. Strip out
2002 // control copies
2003 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2004 if (remove_dead_region(phase, can_reshape)) return this;
2005 return NULL;
2006 }
2007
2008 //------------------------------Value------------------------------------------
2009 const Type *MemBarNode::Value( PhaseTransform *phase ) const {
2010 if( !in(0) ) return Type::TOP;
2011 if( phase->type(in(0)) == Type::TOP )
2012 return Type::TOP;
2013 return TypeTuple::MEMBAR;
2014 }
2015
2016 //------------------------------match------------------------------------------
2017 // Construct projections for memory.
2018 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) {
2019 switch (proj->_con) {
2020 case TypeFunc::Control:
2021 case TypeFunc::Memory:
2022 return new (m->C, 1) MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
2023 }
2024 ShouldNotReachHere();
2025 return NULL;
2026 }
2027
2028 //===========================InitializeNode====================================
2029 // SUMMARY:
2030 // This node acts as a memory barrier on raw memory, after some raw stores.
2031 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
2032 // The Initialize can 'capture' suitably constrained stores as raw inits.
2033 // It can coalesce related raw stores into larger units (called 'tiles').
2034 // It can avoid zeroing new storage for memory units which have raw inits.
2035 // At macro-expansion, it is marked 'complete', and does not optimize further.
2036 //
2037 // EXAMPLE:
2038 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
2039 // ctl = incoming control; mem* = incoming memory
2040 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
2041 // First allocate uninitialized memory and fill in the header:
2042 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
2043 // ctl := alloc.Control; mem* := alloc.Memory*
2044 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
2045 // Then initialize to zero the non-header parts of the raw memory block:
2046 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
2047 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
2048 // After the initialize node executes, the object is ready for service:
2049 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
2050 // Suppose its body is immediately initialized as {1,2}:
2051 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
2052 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
2053 // mem.SLICE(#short[*]) := store2
2054 //
2055 // DETAILS:
2056 // An InitializeNode collects and isolates object initialization after
2057 // an AllocateNode and before the next possible safepoint. As a
2058 // memory barrier (MemBarNode), it keeps critical stores from drifting
2059 // down past any safepoint or any publication of the allocation.
2060 // Before this barrier, a newly-allocated object may have uninitialized bits.
2061 // After this barrier, it may be treated as a real oop, and GC is allowed.
2062 //
2063 // The semantics of the InitializeNode include an implicit zeroing of
2064 // the new object from object header to the end of the object.
2065 // (The object header and end are determined by the AllocateNode.)
2066 //
2067 // Certain stores may be added as direct inputs to the InitializeNode.
2068 // These stores must update raw memory, and they must be to addresses
2069 // derived from the raw address produced by AllocateNode, and with
2070 // a constant offset. They must be ordered by increasing offset.
2071 // The first one is at in(RawStores), the last at in(req()-1).
2072 // Unlike most memory operations, they are not linked in a chain,
2073 // but are displayed in parallel as users of the rawmem output of
2074 // the allocation.
2075 //
2076 // (See comments in InitializeNode::capture_store, which continue
2077 // the example given above.)
2078 //
2079 // When the associated Allocate is macro-expanded, the InitializeNode
2080 // may be rewritten to optimize collected stores. A ClearArrayNode
2081 // may also be created at that point to represent any required zeroing.
2082 // The InitializeNode is then marked 'complete', prohibiting further
2083 // capturing of nearby memory operations.
2084 //
2085 // During macro-expansion, all captured initializations which store
2086 // constant values of 32 bits or smaller are coalesced (if advantagous)
2087 // into larger 'tiles' 32 or 64 bits. This allows an object to be
2088 // initialized in fewer memory operations. Memory words which are
2089 // covered by neither tiles nor non-constant stores are pre-zeroed
2090 // by explicit stores of zero. (The code shape happens to do all
2091 // zeroing first, then all other stores, with both sequences occurring
2092 // in order of ascending offsets.)
2093 //
2094 // Alternatively, code may be inserted between an AllocateNode and its
2095 // InitializeNode, to perform arbitrary initialization of the new object.
2096 // E.g., the object copying intrinsics insert complex data transfers here.
2097 // The initialization must then be marked as 'complete' disable the
2098 // built-in zeroing semantics and the collection of initializing stores.
2099 //
2100 // While an InitializeNode is incomplete, reads from the memory state
2101 // produced by it are optimizable if they match the control edge and
2102 // new oop address associated with the allocation/initialization.
2103 // They return a stored value (if the offset matches) or else zero.
2104 // A write to the memory state, if it matches control and address,
2105 // and if it is to a constant offset, may be 'captured' by the
2106 // InitializeNode. It is cloned as a raw memory operation and rewired
2107 // inside the initialization, to the raw oop produced by the allocation.
2108 // Operations on addresses which are provably distinct (e.g., to
2109 // other AllocateNodes) are allowed to bypass the initialization.
2110 //
2111 // The effect of all this is to consolidate object initialization
2112 // (both arrays and non-arrays, both piecewise and bulk) into a
2113 // single location, where it can be optimized as a unit.
2114 //
2115 // Only stores with an offset less than TrackedInitializationLimit words
2116 // will be considered for capture by an InitializeNode. This puts a
2117 // reasonable limit on the complexity of optimized initializations.
2118
2119 //---------------------------InitializeNode------------------------------------
2120 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
2121 : _is_complete(false),
2122 MemBarNode(C, adr_type, rawoop)
2123 {
2124 init_class_id(Class_Initialize);
2125
2126 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
2127 assert(in(RawAddress) == rawoop, "proper init");
2128 // Note: allocation() can be NULL, for secondary initialization barriers
2129 }
2130
2131 // Since this node is not matched, it will be processed by the
2132 // register allocator. Declare that there are no constraints
2133 // on the allocation of the RawAddress edge.
2134 const RegMask &InitializeNode::in_RegMask(uint idx) const {
2135 // This edge should be set to top, by the set_complete. But be conservative.
2136 if (idx == InitializeNode::RawAddress)
2137 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
2138 return RegMask::Empty;
2139 }
2140
2141 Node* InitializeNode::memory(uint alias_idx) {
2142 Node* mem = in(Memory);
2143 if (mem->is_MergeMem()) {
2144 return mem->as_MergeMem()->memory_at(alias_idx);
2145 } else {
2146 // incoming raw memory is not split
2147 return mem;
2148 }
2149 }
2150
2151 bool InitializeNode::is_non_zero() {
2152 if (is_complete()) return false;
2153 remove_extra_zeroes();
2154 return (req() > RawStores);
2155 }
2156
2157 void InitializeNode::set_complete(PhaseGVN* phase) {
2158 assert(!is_complete(), "caller responsibility");
2159 _is_complete = true;
2160
2161 // After this node is complete, it contains a bunch of
2162 // raw-memory initializations. There is no need for
2163 // it to have anything to do with non-raw memory effects.
2164 // Therefore, tell all non-raw users to re-optimize themselves,
2165 // after skipping the memory effects of this initialization.
2166 PhaseIterGVN* igvn = phase->is_IterGVN();
2167 if (igvn) igvn->add_users_to_worklist(this);
2168 }
2169
2170 // convenience function
2171 // return false if the init contains any stores already
2172 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
2173 InitializeNode* init = initialization();
2174 if (init == NULL || init->is_complete()) return false;
2175 init->remove_extra_zeroes();
2176 // for now, if this allocation has already collected any inits, bail:
2177 if (init->is_non_zero()) return false;
2178 init->set_complete(phase);
2179 return true;
2180 }
2181
2182 void InitializeNode::remove_extra_zeroes() {
2183 if (req() == RawStores) return;
2184 Node* zmem = zero_memory();
2185 uint fill = RawStores;
2186 for (uint i = fill; i < req(); i++) {
2187 Node* n = in(i);
2188 if (n->is_top() || n == zmem) continue; // skip
2189 if (fill < i) set_req(fill, n); // compact
2190 ++fill;
2191 }
2192 // delete any empty spaces created:
2193 while (fill < req()) {
2194 del_req(fill);
2195 }
2196 }
2197
2198 // Helper for remembering which stores go with which offsets.
2199 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) {
2200 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
2201 intptr_t offset = -1;
2202 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
2203 phase, offset);
2204 if (base == NULL) return -1; // something is dead,
2205 if (offset < 0) return -1; // dead, dead
2206 return offset;
2207 }
2208
2209 // Helper for proving that an initialization expression is
2210 // "simple enough" to be folded into an object initialization.
2211 // Attempts to prove that a store's initial value 'n' can be captured
2212 // within the initialization without creating a vicious cycle, such as:
2213 // { Foo p = new Foo(); p.next = p; }
2214 // True for constants and parameters and small combinations thereof.
2215 bool InitializeNode::detect_init_independence(Node* n,
2216 bool st_is_pinned,
2217 int& count) {
2218 if (n == NULL) return true; // (can this really happen?)
2219 if (n->is_Proj()) n = n->in(0);
2220 if (n == this) return false; // found a cycle
2221 if (n->is_Con()) return true;
2222 if (n->is_Start()) return true; // params, etc., are OK
2223 if (n->is_Root()) return true; // even better
2224
2225 Node* ctl = n->in(0);
2226 if (ctl != NULL && !ctl->is_top()) {
2227 if (ctl->is_Proj()) ctl = ctl->in(0);
2228 if (ctl == this) return false;
2229
2230 // If we already know that the enclosing memory op is pinned right after
2231 // the init, then any control flow that the store has picked up
2232 // must have preceded the init, or else be equal to the init.
2233 // Even after loop optimizations (which might change control edges)
2234 // a store is never pinned *before* the availability of its inputs.
2235 if (!MemNode::detect_dominating_control(ctl, this->in(0)))
2236 return false; // failed to prove a good control
2237
2238 }
2239
2240 // Check data edges for possible dependencies on 'this'.
2241 if ((count += 1) > 20) return false; // complexity limit
2242 for (uint i = 1; i < n->req(); i++) {
2243 Node* m = n->in(i);
2244 if (m == NULL || m == n || m->is_top()) continue;
2245 uint first_i = n->find_edge(m);
2246 if (i != first_i) continue; // process duplicate edge just once
2247 if (!detect_init_independence(m, st_is_pinned, count)) {
2248 return false;
2249 }
2250 }
2251
2252 return true;
2253 }
2254
2255 // Here are all the checks a Store must pass before it can be moved into
2256 // an initialization. Returns zero if a check fails.
2257 // On success, returns the (constant) offset to which the store applies,
2258 // within the initialized memory.
2259 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase) {
2260 const int FAIL = 0;
2261 if (st->req() != MemNode::ValueIn + 1)
2262 return FAIL; // an inscrutable StoreNode (card mark?)
2263 Node* ctl = st->in(MemNode::Control);
2264 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this))
2265 return FAIL; // must be unconditional after the initialization
2266 Node* mem = st->in(MemNode::Memory);
2267 if (!(mem->is_Proj() && mem->in(0) == this))
2268 return FAIL; // must not be preceded by other stores
2269 Node* adr = st->in(MemNode::Address);
2270 intptr_t offset;
2271 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
2272 if (alloc == NULL)
2273 return FAIL; // inscrutable address
2274 if (alloc != allocation())
2275 return FAIL; // wrong allocation! (store needs to float up)
2276 Node* val = st->in(MemNode::ValueIn);
2277 int complexity_count = 0;
2278 if (!detect_init_independence(val, true, complexity_count))
2279 return FAIL; // stored value must be 'simple enough'
2280
2281 return offset; // success
2282 }
2283
2284 // Find the captured store in(i) which corresponds to the range
2285 // [start..start+size) in the initialized object.
2286 // If there is one, return its index i. If there isn't, return the
2287 // negative of the index where it should be inserted.
2288 // Return 0 if the queried range overlaps an initialization boundary
2289 // or if dead code is encountered.
2290 // If size_in_bytes is zero, do not bother with overlap checks.
2291 int InitializeNode::captured_store_insertion_point(intptr_t start,
2292 int size_in_bytes,
2293 PhaseTransform* phase) {
2294 const int FAIL = 0, MAX_STORE = BytesPerLong;
2295
2296 if (is_complete())
2297 return FAIL; // arraycopy got here first; punt
2298
2299 assert(allocation() != NULL, "must be present");
2300
2301 // no negatives, no header fields:
2302 if (start < (intptr_t) sizeof(oopDesc)) return FAIL;
2303 if (start < (intptr_t) sizeof(arrayOopDesc) &&
2304 start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
2305
2306 // after a certain size, we bail out on tracking all the stores:
2307 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
2308 if (start >= ti_limit) return FAIL;
2309
2310 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
2311 if (i >= limit) return -(int)i; // not found; here is where to put it
2312
2313 Node* st = in(i);
2314 intptr_t st_off = get_store_offset(st, phase);
2315 if (st_off < 0) {
2316 if (st != zero_memory()) {
2317 return FAIL; // bail out if there is dead garbage
2318 }
2319 } else if (st_off > start) {
2320 // ...we are done, since stores are ordered
2321 if (st_off < start + size_in_bytes) {
2322 return FAIL; // the next store overlaps
2323 }
2324 return -(int)i; // not found; here is where to put it
2325 } else if (st_off < start) {
2326 if (size_in_bytes != 0 &&
2327 start < st_off + MAX_STORE &&
2328 start < st_off + st->as_Store()->memory_size()) {
2329 return FAIL; // the previous store overlaps
2330 }
2331 } else {
2332 if (size_in_bytes != 0 &&
2333 st->as_Store()->memory_size() != size_in_bytes) {
2334 return FAIL; // mismatched store size
2335 }
2336 return i;
2337 }
2338
2339 ++i;
2340 }
2341 }
2342
2343 // Look for a captured store which initializes at the offset 'start'
2344 // with the given size. If there is no such store, and no other
2345 // initialization interferes, then return zero_memory (the memory
2346 // projection of the AllocateNode).
2347 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
2348 PhaseTransform* phase) {
2349 assert(stores_are_sane(phase), "");
2350 int i = captured_store_insertion_point(start, size_in_bytes, phase);
2351 if (i == 0) {
2352 return NULL; // something is dead
2353 } else if (i < 0) {
2354 return zero_memory(); // just primordial zero bits here
2355 } else {
2356 Node* st = in(i); // here is the store at this position
2357 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
2358 return st;
2359 }
2360 }
2361
2362 // Create, as a raw pointer, an address within my new object at 'offset'.
2363 Node* InitializeNode::make_raw_address(intptr_t offset,
2364 PhaseTransform* phase) {
2365 Node* addr = in(RawAddress);
2366 if (offset != 0) {
2367 Compile* C = phase->C;
2368 addr = phase->transform( new (C, 4) AddPNode(C->top(), addr,
2369 phase->MakeConX(offset)) );
2370 }
2371 return addr;
2372 }
2373
2374 // Clone the given store, converting it into a raw store
2375 // initializing a field or element of my new object.
2376 // Caller is responsible for retiring the original store,
2377 // with subsume_node or the like.
2378 //
2379 // From the example above InitializeNode::InitializeNode,
2380 // here are the old stores to be captured:
2381 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
2382 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
2383 //
2384 // Here is the changed code; note the extra edges on init:
2385 // alloc = (Allocate ...)
2386 // rawoop = alloc.RawAddress
2387 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
2388 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
2389 // init = (Initialize alloc.Control alloc.Memory rawoop
2390 // rawstore1 rawstore2)
2391 //
2392 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
2393 PhaseTransform* phase) {
2394 assert(stores_are_sane(phase), "");
2395
2396 if (start < 0) return NULL;
2397 assert(can_capture_store(st, phase) == start, "sanity");
2398
2399 Compile* C = phase->C;
2400 int size_in_bytes = st->memory_size();
2401 int i = captured_store_insertion_point(start, size_in_bytes, phase);
2402 if (i == 0) return NULL; // bail out
2403 Node* prev_mem = NULL; // raw memory for the captured store
2404 if (i > 0) {
2405 prev_mem = in(i); // there is a pre-existing store under this one
2406 set_req(i, C->top()); // temporarily disconnect it
2407 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
2408 } else {
2409 i = -i; // no pre-existing store
2410 prev_mem = zero_memory(); // a slice of the newly allocated object
2411 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
2412 set_req(--i, C->top()); // reuse this edge; it has been folded away
2413 else
2414 ins_req(i, C->top()); // build a new edge
2415 }
2416 Node* new_st = st->clone();
2417 new_st->set_req(MemNode::Control, in(Control));
2418 new_st->set_req(MemNode::Memory, prev_mem);
2419 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
2420 new_st = phase->transform(new_st);
2421
2422 // At this point, new_st might have swallowed a pre-existing store
2423 // at the same offset, or perhaps new_st might have disappeared,
2424 // if it redundantly stored the same value (or zero to fresh memory).
2425
2426 // In any case, wire it in:
2427 set_req(i, new_st);
2428
2429 // The caller may now kill the old guy.
2430 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
2431 assert(check_st == new_st || check_st == NULL, "must be findable");
2432 assert(!is_complete(), "");
2433 return new_st;
2434 }
2435
2436 static bool store_constant(jlong* tiles, int num_tiles,
2437 intptr_t st_off, int st_size,
2438 jlong con) {
2439 if ((st_off & (st_size-1)) != 0)
2440 return false; // strange store offset (assume size==2**N)
2441 address addr = (address)tiles + st_off;
2442 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
2443 switch (st_size) {
2444 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
2445 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
2446 case sizeof(jint): *(jint*) addr = (jint) con; break;
2447 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
2448 default: return false; // strange store size (detect size!=2**N here)
2449 }
2450 return true; // return success to caller
2451 }
2452
2453 // Coalesce subword constants into int constants and possibly
2454 // into long constants. The goal, if the CPU permits,
2455 // is to initialize the object with a small number of 64-bit tiles.
2456 // Also, convert floating-point constants to bit patterns.
2457 // Non-constants are not relevant to this pass.
2458 //
2459 // In terms of the running example on InitializeNode::InitializeNode
2460 // and InitializeNode::capture_store, here is the transformation
2461 // of rawstore1 and rawstore2 into rawstore12:
2462 // alloc = (Allocate ...)
2463 // rawoop = alloc.RawAddress
2464 // tile12 = 0x00010002
2465 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
2466 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
2467 //
2468 void
2469 InitializeNode::coalesce_subword_stores(intptr_t header_size,
2470 Node* size_in_bytes,
2471 PhaseGVN* phase) {
2472 Compile* C = phase->C;
2473
2474 assert(stores_are_sane(phase), "");
2475 // Note: After this pass, they are not completely sane,
2476 // since there may be some overlaps.
2477
2478 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
2479
2480 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
2481 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
2482 size_limit = MIN2(size_limit, ti_limit);
2483 size_limit = align_size_up(size_limit, BytesPerLong);
2484 int num_tiles = size_limit / BytesPerLong;
2485
2486 // allocate space for the tile map:
2487 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
2488 jlong tiles_buf[small_len];
2489 Node* nodes_buf[small_len];
2490 jlong inits_buf[small_len];
2491 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
2492 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
2493 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
2494 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
2495 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
2496 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
2497 // tiles: exact bitwise model of all primitive constants
2498 // nodes: last constant-storing node subsumed into the tiles model
2499 // inits: which bytes (in each tile) are touched by any initializations
2500
2501 //// Pass A: Fill in the tile model with any relevant stores.
2502
2503 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
2504 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
2505 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
2506 Node* zmem = zero_memory(); // initially zero memory state
2507 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
2508 Node* st = in(i);
2509 intptr_t st_off = get_store_offset(st, phase);
2510
2511 // Figure out the store's offset and constant value:
2512 if (st_off < header_size) continue; //skip (ignore header)
2513 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
2514 int st_size = st->as_Store()->memory_size();
2515 if (st_off + st_size > size_limit) break;
2516
2517 // Record which bytes are touched, whether by constant or not.
2518 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
2519 continue; // skip (strange store size)
2520
2521 const Type* val = phase->type(st->in(MemNode::ValueIn));
2522 if (!val->singleton()) continue; //skip (non-con store)
2523 BasicType type = val->basic_type();
2524
2525 jlong con = 0;
2526 switch (type) {
2527 case T_INT: con = val->is_int()->get_con(); break;
2528 case T_LONG: con = val->is_long()->get_con(); break;
2529 case T_FLOAT: con = jint_cast(val->getf()); break;
2530 case T_DOUBLE: con = jlong_cast(val->getd()); break;
2531 default: continue; //skip (odd store type)
2532 }
2533
2534 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
2535 st->Opcode() == Op_StoreL) {
2536 continue; // This StoreL is already optimal.
2537 }
2538
2539 // Store down the constant.
2540 store_constant(tiles, num_tiles, st_off, st_size, con);
2541
2542 intptr_t j = st_off >> LogBytesPerLong;
2543
2544 if (type == T_INT && st_size == BytesPerInt
2545 && (st_off & BytesPerInt) == BytesPerInt) {
2546 jlong lcon = tiles[j];
2547 if (!Matcher::isSimpleConstant64(lcon) &&
2548 st->Opcode() == Op_StoreI) {
2549 // This StoreI is already optimal by itself.
2550 jint* intcon = (jint*) &tiles[j];
2551 intcon[1] = 0; // undo the store_constant()
2552
2553 // If the previous store is also optimal by itself, back up and
2554 // undo the action of the previous loop iteration... if we can.
2555 // But if we can't, just let the previous half take care of itself.
2556 st = nodes[j];
2557 st_off -= BytesPerInt;
2558 con = intcon[0];
2559 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) {
2560 assert(st_off >= header_size, "still ignoring header");
2561 assert(get_store_offset(st, phase) == st_off, "must be");
2562 assert(in(i-1) == zmem, "must be");
2563 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
2564 assert(con == tcon->is_int()->get_con(), "must be");
2565 // Undo the effects of the previous loop trip, which swallowed st:
2566 intcon[0] = 0; // undo store_constant()
2567 set_req(i-1, st); // undo set_req(i, zmem)
2568 nodes[j] = NULL; // undo nodes[j] = st
2569 --old_subword; // undo ++old_subword
2570 }
2571 continue; // This StoreI is already optimal.
2572 }
2573 }
2574
2575 // This store is not needed.
2576 set_req(i, zmem);
2577 nodes[j] = st; // record for the moment
2578 if (st_size < BytesPerLong) // something has changed
2579 ++old_subword; // includes int/float, but who's counting...
2580 else ++old_long;
2581 }
2582
2583 if ((old_subword + old_long) == 0)
2584 return; // nothing more to do
2585
2586 //// Pass B: Convert any non-zero tiles into optimal constant stores.
2587 // Be sure to insert them before overlapping non-constant stores.
2588 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
2589 for (int j = 0; j < num_tiles; j++) {
2590 jlong con = tiles[j];
2591 jlong init = inits[j];
2592 if (con == 0) continue;
2593 jint con0, con1; // split the constant, address-wise
2594 jint init0, init1; // split the init map, address-wise
2595 { union { jlong con; jint intcon[2]; } u;
2596 u.con = con;
2597 con0 = u.intcon[0];
2598 con1 = u.intcon[1];
2599 u.con = init;
2600 init0 = u.intcon[0];
2601 init1 = u.intcon[1];
2602 }
2603
2604 Node* old = nodes[j];
2605 assert(old != NULL, "need the prior store");
2606 intptr_t offset = (j * BytesPerLong);
2607
2608 bool split = !Matcher::isSimpleConstant64(con);
2609
2610 if (offset < header_size) {
2611 assert(offset + BytesPerInt >= header_size, "second int counts");
2612 assert(*(jint*)&tiles[j] == 0, "junk in header");
2613 split = true; // only the second word counts
2614 // Example: int a[] = { 42 ... }
2615 } else if (con0 == 0 && init0 == -1) {
2616 split = true; // first word is covered by full inits
2617 // Example: int a[] = { ... foo(), 42 ... }
2618 } else if (con1 == 0 && init1 == -1) {
2619 split = true; // second word is covered by full inits
2620 // Example: int a[] = { ... 42, foo() ... }
2621 }
2622
2623 // Here's a case where init0 is neither 0 nor -1:
2624 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
2625 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
2626 // In this case the tile is not split; it is (jlong)42.
2627 // The big tile is stored down, and then the foo() value is inserted.
2628 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
2629
2630 Node* ctl = old->in(MemNode::Control);
2631 Node* adr = make_raw_address(offset, phase);
2632 const TypePtr* atp = TypeRawPtr::BOTTOM;
2633
2634 // One or two coalesced stores to plop down.
2635 Node* st[2];
2636 intptr_t off[2];
2637 int nst = 0;
2638 if (!split) {
2639 ++new_long;
2640 off[nst] = offset;
2641 st[nst++] = StoreNode::make(C, ctl, zmem, adr, atp,
2642 phase->longcon(con), T_LONG);
2643 } else {
2644 // Omit either if it is a zero.
2645 if (con0 != 0) {
2646 ++new_int;
2647 off[nst] = offset;
2648 st[nst++] = StoreNode::make(C, ctl, zmem, adr, atp,
2649 phase->intcon(con0), T_INT);
2650 }
2651 if (con1 != 0) {
2652 ++new_int;
2653 offset += BytesPerInt;
2654 adr = make_raw_address(offset, phase);
2655 off[nst] = offset;
2656 st[nst++] = StoreNode::make(C, ctl, zmem, adr, atp,
2657 phase->intcon(con1), T_INT);
2658 }
2659 }
2660
2661 // Insert second store first, then the first before the second.
2662 // Insert each one just before any overlapping non-constant stores.
2663 while (nst > 0) {
2664 Node* st1 = st[--nst];
2665 C->copy_node_notes_to(st1, old);
2666 st1 = phase->transform(st1);
2667 offset = off[nst];
2668 assert(offset >= header_size, "do not smash header");
2669 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
2670 guarantee(ins_idx != 0, "must re-insert constant store");
2671 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
2672 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
2673 set_req(--ins_idx, st1);
2674 else
2675 ins_req(ins_idx, st1);
2676 }
2677 }
2678
2679 if (PrintCompilation && WizardMode)
2680 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
2681 old_subword, old_long, new_int, new_long);
2682 if (C->log() != NULL)
2683 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
2684 old_subword, old_long, new_int, new_long);
2685
2686 // Clean up any remaining occurrences of zmem:
2687 remove_extra_zeroes();
2688 }
2689
2690 // Explore forward from in(start) to find the first fully initialized
2691 // word, and return its offset. Skip groups of subword stores which
2692 // together initialize full words. If in(start) is itself part of a
2693 // fully initialized word, return the offset of in(start). If there
2694 // are no following full-word stores, or if something is fishy, return
2695 // a negative value.
2696 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
2697 int int_map = 0;
2698 intptr_t int_map_off = 0;
2699 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
2700
2701 for (uint i = start, limit = req(); i < limit; i++) {
2702 Node* st = in(i);
2703
2704 intptr_t st_off = get_store_offset(st, phase);
2705 if (st_off < 0) break; // return conservative answer
2706
2707 int st_size = st->as_Store()->memory_size();
2708 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
2709 return st_off; // we found a complete word init
2710 }
2711
2712 // update the map:
2713
2714 intptr_t this_int_off = align_size_down(st_off, BytesPerInt);
2715 if (this_int_off != int_map_off) {
2716 // reset the map:
2717 int_map = 0;
2718 int_map_off = this_int_off;
2719 }
2720
2721 int subword_off = st_off - this_int_off;
2722 int_map |= right_n_bits(st_size) << subword_off;
2723 if ((int_map & FULL_MAP) == FULL_MAP) {
2724 return this_int_off; // we found a complete word init
2725 }
2726
2727 // Did this store hit or cross the word boundary?
2728 intptr_t next_int_off = align_size_down(st_off + st_size, BytesPerInt);
2729 if (next_int_off == this_int_off + BytesPerInt) {
2730 // We passed the current int, without fully initializing it.
2731 int_map_off = next_int_off;
2732 int_map >>= BytesPerInt;
2733 } else if (next_int_off > this_int_off + BytesPerInt) {
2734 // We passed the current and next int.
2735 return this_int_off + BytesPerInt;
2736 }
2737 }
2738
2739 return -1;
2740 }
2741
2742
2743 // Called when the associated AllocateNode is expanded into CFG.
2744 // At this point, we may perform additional optimizations.
2745 // Linearize the stores by ascending offset, to make memory
2746 // activity as coherent as possible.
2747 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
2748 intptr_t header_size,
2749 Node* size_in_bytes,
2750 PhaseGVN* phase) {
2751 assert(!is_complete(), "not already complete");
2752 assert(stores_are_sane(phase), "");
2753 assert(allocation() != NULL, "must be present");
2754
2755 remove_extra_zeroes();
2756
2757 if (ReduceFieldZeroing || ReduceBulkZeroing)
2758 // reduce instruction count for common initialization patterns
2759 coalesce_subword_stores(header_size, size_in_bytes, phase);
2760
2761 Node* zmem = zero_memory(); // initially zero memory state
2762 Node* inits = zmem; // accumulating a linearized chain of inits
2763 #ifdef ASSERT
2764 intptr_t last_init_off = sizeof(oopDesc); // previous init offset
2765 intptr_t last_init_end = sizeof(oopDesc); // previous init offset+size
2766 intptr_t last_tile_end = sizeof(oopDesc); // previous tile offset+size
2767 #endif
2768 intptr_t zeroes_done = header_size;
2769
2770 bool do_zeroing = true; // we might give up if inits are very sparse
2771 int big_init_gaps = 0; // how many large gaps have we seen?
2772
2773 if (ZeroTLAB) do_zeroing = false;
2774 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
2775
2776 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
2777 Node* st = in(i);
2778 intptr_t st_off = get_store_offset(st, phase);
2779 if (st_off < 0)
2780 break; // unknown junk in the inits
2781 if (st->in(MemNode::Memory) != zmem)
2782 break; // complicated store chains somehow in list
2783
2784 int st_size = st->as_Store()->memory_size();
2785 intptr_t next_init_off = st_off + st_size;
2786
2787 if (do_zeroing && zeroes_done < next_init_off) {
2788 // See if this store needs a zero before it or under it.
2789 intptr_t zeroes_needed = st_off;
2790
2791 if (st_size < BytesPerInt) {
2792 // Look for subword stores which only partially initialize words.
2793 // If we find some, we must lay down some word-level zeroes first,
2794 // underneath the subword stores.
2795 //
2796 // Examples:
2797 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
2798 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
2799 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
2800 //
2801 // Note: coalesce_subword_stores may have already done this,
2802 // if it was prompted by constant non-zero subword initializers.
2803 // But this case can still arise with non-constant stores.
2804
2805 intptr_t next_full_store = find_next_fullword_store(i, phase);
2806
2807 // In the examples above:
2808 // in(i) p q r s x y z
2809 // st_off 12 13 14 15 12 13 14
2810 // st_size 1 1 1 1 1 1 1
2811 // next_full_s. 12 16 16 16 16 16 16
2812 // z's_done 12 16 16 16 12 16 12
2813 // z's_needed 12 16 16 16 16 16 16
2814 // zsize 0 0 0 0 4 0 4
2815 if (next_full_store < 0) {
2816 // Conservative tack: Zero to end of current word.
2817 zeroes_needed = align_size_up(zeroes_needed, BytesPerInt);
2818 } else {
2819 // Zero to beginning of next fully initialized word.
2820 // Or, don't zero at all, if we are already in that word.
2821 assert(next_full_store >= zeroes_needed, "must go forward");
2822 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
2823 zeroes_needed = next_full_store;
2824 }
2825 }
2826
2827 if (zeroes_needed > zeroes_done) {
2828 intptr_t zsize = zeroes_needed - zeroes_done;
2829 // Do some incremental zeroing on rawmem, in parallel with inits.
2830 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
2831 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
2832 zeroes_done, zeroes_needed,
2833 phase);
2834 zeroes_done = zeroes_needed;
2835 if (zsize > Matcher::init_array_short_size && ++big_init_gaps > 2)
2836 do_zeroing = false; // leave the hole, next time
2837 }
2838 }
2839
2840 // Collect the store and move on:
2841 st->set_req(MemNode::Memory, inits);
2842 inits = st; // put it on the linearized chain
2843 set_req(i, zmem); // unhook from previous position
2844
2845 if (zeroes_done == st_off)
2846 zeroes_done = next_init_off;
2847
2848 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
2849
2850 #ifdef ASSERT
2851 // Various order invariants. Weaker than stores_are_sane because
2852 // a large constant tile can be filled in by smaller non-constant stores.
2853 assert(st_off >= last_init_off, "inits do not reverse");
2854 last_init_off = st_off;
2855 const Type* val = NULL;
2856 if (st_size >= BytesPerInt &&
2857 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
2858 (int)val->basic_type() < (int)T_OBJECT) {
2859 assert(st_off >= last_tile_end, "tiles do not overlap");
2860 assert(st_off >= last_init_end, "tiles do not overwrite inits");
2861 last_tile_end = MAX2(last_tile_end, next_init_off);
2862 } else {
2863 intptr_t st_tile_end = align_size_up(next_init_off, BytesPerLong);
2864 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
2865 assert(st_off >= last_init_end, "inits do not overlap");
2866 last_init_end = next_init_off; // it's a non-tile
2867 }
2868 #endif //ASSERT
2869 }
2870
2871 remove_extra_zeroes(); // clear out all the zmems left over
2872 add_req(inits);
2873
2874 if (!ZeroTLAB) {
2875 // If anything remains to be zeroed, zero it all now.
2876 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
2877 // if it is the last unused 4 bytes of an instance, forget about it
2878 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
2879 if (zeroes_done + BytesPerLong >= size_limit) {
2880 assert(allocation() != NULL, "");
2881 Node* klass_node = allocation()->in(AllocateNode::KlassNode);
2882 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass();
2883 if (zeroes_done == k->layout_helper())
2884 zeroes_done = size_limit;
2885 }
2886 if (zeroes_done < size_limit) {
2887 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
2888 zeroes_done, size_in_bytes, phase);
2889 }
2890 }
2891
2892 set_complete(phase);
2893 return rawmem;
2894 }
2895
2896
2897 #ifdef ASSERT
2898 bool InitializeNode::stores_are_sane(PhaseTransform* phase) {
2899 if (is_complete())
2900 return true; // stores could be anything at this point
2901 intptr_t last_off = sizeof(oopDesc);
2902 for (uint i = InitializeNode::RawStores; i < req(); i++) {
2903 Node* st = in(i);
2904 intptr_t st_off = get_store_offset(st, phase);
2905 if (st_off < 0) continue; // ignore dead garbage
2906 if (last_off > st_off) {
2907 tty->print_cr("*** bad store offset at %d: %d > %d", i, last_off, st_off);
2908 this->dump(2);
2909 assert(false, "ascending store offsets");
2910 return false;
2911 }
2912 last_off = st_off + st->as_Store()->memory_size();
2913 }
2914 return true;
2915 }
2916 #endif //ASSERT
2917
2918
2919
2920
2921 //============================MergeMemNode=====================================
2922 //
2923 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
2924 // contributing store or call operations. Each contributor provides the memory
2925 // state for a particular "alias type" (see Compile::alias_type). For example,
2926 // if a MergeMem has an input X for alias category #6, then any memory reference
2927 // to alias category #6 may use X as its memory state input, as an exact equivalent
2928 // to using the MergeMem as a whole.
2929 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
2930 //
2931 // (Here, the <N> notation gives the index of the relevant adr_type.)
2932 //
2933 // In one special case (and more cases in the future), alias categories overlap.
2934 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
2935 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
2936 // it is exactly equivalent to that state W:
2937 // MergeMem(<Bot>: W) <==> W
2938 //
2939 // Usually, the merge has more than one input. In that case, where inputs
2940 // overlap (i.e., one is Bot), the narrower alias type determines the memory
2941 // state for that type, and the wider alias type (Bot) fills in everywhere else:
2942 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
2943 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
2944 //
2945 // A merge can take a "wide" memory state as one of its narrow inputs.
2946 // This simply means that the merge observes out only the relevant parts of
2947 // the wide input. That is, wide memory states arriving at narrow merge inputs
2948 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
2949 //
2950 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
2951 // and that memory slices "leak through":
2952 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
2953 //
2954 // But, in such a cascade, repeated memory slices can "block the leak":
2955 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
2956 //
2957 // In the last example, Y is not part of the combined memory state of the
2958 // outermost MergeMem. The system must, of course, prevent unschedulable
2959 // memory states from arising, so you can be sure that the state Y is somehow
2960 // a precursor to state Y'.
2961 //
2962 //
2963 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
2964 // of each MergeMemNode array are exactly the numerical alias indexes, including
2965 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
2966 // Compile::alias_type (and kin) produce and manage these indexes.
2967 //
2968 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
2969 // (Note that this provides quick access to the top node inside MergeMem methods,
2970 // without the need to reach out via TLS to Compile::current.)
2971 //
2972 // As a consequence of what was just described, a MergeMem that represents a full
2973 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
2974 // containing all alias categories.
2975 //
2976 // MergeMem nodes never (?) have control inputs, so in(0) is NULL.
2977 //
2978 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
2979 // a memory state for the alias type <N>, or else the top node, meaning that
2980 // there is no particular input for that alias type. Note that the length of
2981 // a MergeMem is variable, and may be extended at any time to accommodate new
2982 // memory states at larger alias indexes. When merges grow, they are of course
2983 // filled with "top" in the unused in() positions.
2984 //
2985 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
2986 // (Top was chosen because it works smoothly with passes like GCM.)
2987 //
2988 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
2989 // the type of random VM bits like TLS references.) Since it is always the
2990 // first non-Bot memory slice, some low-level loops use it to initialize an
2991 // index variable: for (i = AliasIdxRaw; i < req(); i++).
2992 //
2993 //
2994 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
2995 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
2996 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
2997 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
2998 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
2999 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
3000 //
3001 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
3002 // really that different from the other memory inputs. An abbreviation called
3003 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
3004 //
3005 //
3006 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
3007 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
3008 // that "emerges though" the base memory will be marked as excluding the alias types
3009 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
3010 //
3011 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
3012 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
3013 //
3014 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
3015 // (It is currently unimplemented.) As you can see, the resulting merge is
3016 // actually a disjoint union of memory states, rather than an overlay.
3017 //
3018
3019 //------------------------------MergeMemNode-----------------------------------
3020 Node* MergeMemNode::make_empty_memory() {
3021 Node* empty_memory = (Node*) Compile::current()->top();
3022 assert(empty_memory->is_top(), "correct sentinel identity");
3023 return empty_memory;
3024 }
3025
3026 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
3027 init_class_id(Class_MergeMem);
3028 // all inputs are nullified in Node::Node(int)
3029 // set_input(0, NULL); // no control input
3030
3031 // Initialize the edges uniformly to top, for starters.
3032 Node* empty_mem = make_empty_memory();
3033 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
3034 init_req(i,empty_mem);
3035 }
3036 assert(empty_memory() == empty_mem, "");
3037
3038 if( new_base != NULL && new_base->is_MergeMem() ) {
3039 MergeMemNode* mdef = new_base->as_MergeMem();
3040 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
3041 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
3042 mms.set_memory(mms.memory2());
3043 }
3044 assert(base_memory() == mdef->base_memory(), "");
3045 } else {
3046 set_base_memory(new_base);
3047 }
3048 }
3049
3050 // Make a new, untransformed MergeMem with the same base as 'mem'.
3051 // If mem is itself a MergeMem, populate the result with the same edges.
3052 MergeMemNode* MergeMemNode::make(Compile* C, Node* mem) {
3053 return new(C, 1+Compile::AliasIdxRaw) MergeMemNode(mem);
3054 }
3055
3056 //------------------------------cmp--------------------------------------------
3057 uint MergeMemNode::hash() const { return NO_HASH; }
3058 uint MergeMemNode::cmp( const Node &n ) const {
3059 return (&n == this); // Always fail except on self
3060 }
3061
3062 //------------------------------Identity---------------------------------------
3063 Node* MergeMemNode::Identity(PhaseTransform *phase) {
3064 // Identity if this merge point does not record any interesting memory
3065 // disambiguations.
3066 Node* base_mem = base_memory();
3067 Node* empty_mem = empty_memory();
3068 if (base_mem != empty_mem) { // Memory path is not dead?
3069 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3070 Node* mem = in(i);
3071 if (mem != empty_mem && mem != base_mem) {
3072 return this; // Many memory splits; no change
3073 }
3074 }
3075 }
3076 return base_mem; // No memory splits; ID on the one true input
3077 }
3078
3079 //------------------------------Ideal------------------------------------------
3080 // This method is invoked recursively on chains of MergeMem nodes
3081 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3082 // Remove chain'd MergeMems
3083 //
3084 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
3085 // relative to the "in(Bot)". Since we are patching both at the same time,
3086 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
3087 // but rewrite each "in(i)" relative to the new "in(Bot)".
3088 Node *progress = NULL;
3089
3090
3091 Node* old_base = base_memory();
3092 Node* empty_mem = empty_memory();
3093 if (old_base == empty_mem)
3094 return NULL; // Dead memory path.
3095
3096 MergeMemNode* old_mbase;
3097 if (old_base != NULL && old_base->is_MergeMem())
3098 old_mbase = old_base->as_MergeMem();
3099 else
3100 old_mbase = NULL;
3101 Node* new_base = old_base;
3102
3103 // simplify stacked MergeMems in base memory
3104 if (old_mbase) new_base = old_mbase->base_memory();
3105
3106 // the base memory might contribute new slices beyond my req()
3107 if (old_mbase) grow_to_match(old_mbase);
3108
3109 // Look carefully at the base node if it is a phi.
3110 PhiNode* phi_base;
3111 if (new_base != NULL && new_base->is_Phi())
3112 phi_base = new_base->as_Phi();
3113 else
3114 phi_base = NULL;
3115
3116 Node* phi_reg = NULL;
3117 uint phi_len = (uint)-1;
3118 if (phi_base != NULL && !phi_base->is_copy()) {
3119 // do not examine phi if degraded to a copy
3120 phi_reg = phi_base->region();
3121 phi_len = phi_base->req();
3122 // see if the phi is unfinished
3123 for (uint i = 1; i < phi_len; i++) {
3124 if (phi_base->in(i) == NULL) {
3125 // incomplete phi; do not look at it yet!
3126 phi_reg = NULL;
3127 phi_len = (uint)-1;
3128 break;
3129 }
3130 }
3131 }
3132
3133 // Note: We do not call verify_sparse on entry, because inputs
3134 // can normalize to the base_memory via subsume_node or similar
3135 // mechanisms. This method repairs that damage.
3136
3137 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
3138
3139 // Look at each slice.
3140 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3141 Node* old_in = in(i);
3142 // calculate the old memory value
3143 Node* old_mem = old_in;
3144 if (old_mem == empty_mem) old_mem = old_base;
3145 assert(old_mem == memory_at(i), "");
3146
3147 // maybe update (reslice) the old memory value
3148
3149 // simplify stacked MergeMems
3150 Node* new_mem = old_mem;
3151 MergeMemNode* old_mmem;
3152 if (old_mem != NULL && old_mem->is_MergeMem())
3153 old_mmem = old_mem->as_MergeMem();
3154 else
3155 old_mmem = NULL;
3156 if (old_mmem == this) {
3157 // This can happen if loops break up and safepoints disappear.
3158 // A merge of BotPtr (default) with a RawPtr memory derived from a
3159 // safepoint can be rewritten to a merge of the same BotPtr with
3160 // the BotPtr phi coming into the loop. If that phi disappears
3161 // also, we can end up with a self-loop of the mergemem.
3162 // In general, if loops degenerate and memory effects disappear,
3163 // a mergemem can be left looking at itself. This simply means
3164 // that the mergemem's default should be used, since there is
3165 // no longer any apparent effect on this slice.
3166 // Note: If a memory slice is a MergeMem cycle, it is unreachable
3167 // from start. Update the input to TOP.
3168 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
3169 }
3170 else if (old_mmem != NULL) {
3171 new_mem = old_mmem->memory_at(i);
3172 }
3173 // else preceeding memory was not a MergeMem
3174
3175 // replace equivalent phis (unfortunately, they do not GVN together)
3176 if (new_mem != NULL && new_mem != new_base &&
3177 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) {
3178 if (new_mem->is_Phi()) {
3179 PhiNode* phi_mem = new_mem->as_Phi();
3180 for (uint i = 1; i < phi_len; i++) {
3181 if (phi_base->in(i) != phi_mem->in(i)) {
3182 phi_mem = NULL;
3183 break;
3184 }
3185 }
3186 if (phi_mem != NULL) {
3187 // equivalent phi nodes; revert to the def
3188 new_mem = new_base;
3189 }
3190 }
3191 }
3192
3193 // maybe store down a new value
3194 Node* new_in = new_mem;
3195 if (new_in == new_base) new_in = empty_mem;
3196
3197 if (new_in != old_in) {
3198 // Warning: Do not combine this "if" with the previous "if"
3199 // A memory slice might have be be rewritten even if it is semantically
3200 // unchanged, if the base_memory value has changed.
3201 set_req(i, new_in);
3202 progress = this; // Report progress
3203 }
3204 }
3205
3206 if (new_base != old_base) {
3207 set_req(Compile::AliasIdxBot, new_base);
3208 // Don't use set_base_memory(new_base), because we need to update du.
3209 assert(base_memory() == new_base, "");
3210 progress = this;
3211 }
3212
3213 if( base_memory() == this ) {
3214 // a self cycle indicates this memory path is dead
3215 set_req(Compile::AliasIdxBot, empty_mem);
3216 }
3217
3218 // Resolve external cycles by calling Ideal on a MergeMem base_memory
3219 // Recursion must occur after the self cycle check above
3220 if( base_memory()->is_MergeMem() ) {
3221 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
3222 Node *m = phase->transform(new_mbase); // Rollup any cycles
3223 if( m != NULL && (m->is_top() ||
3224 m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem) ) {
3225 // propagate rollup of dead cycle to self
3226 set_req(Compile::AliasIdxBot, empty_mem);
3227 }
3228 }
3229
3230 if( base_memory() == empty_mem ) {
3231 progress = this;
3232 // Cut inputs during Parse phase only.
3233 // During Optimize phase a dead MergeMem node will be subsumed by Top.
3234 if( !can_reshape ) {
3235 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3236 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
3237 }
3238 }
3239 }
3240
3241 if( !progress && base_memory()->is_Phi() && can_reshape ) {
3242 // Check if PhiNode::Ideal's "Split phis through memory merges"
3243 // transform should be attempted. Look for this->phi->this cycle.
3244 uint merge_width = req();
3245 if (merge_width > Compile::AliasIdxRaw) {
3246 PhiNode* phi = base_memory()->as_Phi();
3247 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
3248 if (phi->in(i) == this) {
3249 phase->is_IterGVN()->_worklist.push(phi);
3250 break;
3251 }
3252 }
3253 }
3254 }
3255
3256 assert(verify_sparse(), "please, no dups of base");
3257 return progress;
3258 }
3259
3260 //-------------------------set_base_memory-------------------------------------
3261 void MergeMemNode::set_base_memory(Node *new_base) {
3262 Node* empty_mem = empty_memory();
3263 set_req(Compile::AliasIdxBot, new_base);
3264 assert(memory_at(req()) == new_base, "must set default memory");
3265 // Clear out other occurrences of new_base:
3266 if (new_base != empty_mem) {
3267 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3268 if (in(i) == new_base) set_req(i, empty_mem);
3269 }
3270 }
3271 }
3272
3273 //------------------------------out_RegMask------------------------------------
3274 const RegMask &MergeMemNode::out_RegMask() const {
3275 return RegMask::Empty;
3276 }
3277
3278 //------------------------------dump_spec--------------------------------------
3279 #ifndef PRODUCT
3280 void MergeMemNode::dump_spec(outputStream *st) const {
3281 st->print(" {");
3282 Node* base_mem = base_memory();
3283 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
3284 Node* mem = memory_at(i);
3285 if (mem == base_mem) { st->print(" -"); continue; }
3286 st->print( " N%d:", mem->_idx );
3287 Compile::current()->get_adr_type(i)->dump_on(st);
3288 }
3289 st->print(" }");
3290 }
3291 #endif // !PRODUCT
3292
3293
3294 #ifdef ASSERT
3295 static bool might_be_same(Node* a, Node* b) {
3296 if (a == b) return true;
3297 if (!(a->is_Phi() || b->is_Phi())) return false;
3298 // phis shift around during optimization
3299 return true; // pretty stupid...
3300 }
3301
3302 // verify a narrow slice (either incoming or outgoing)
3303 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
3304 if (!VerifyAliases) return; // don't bother to verify unless requested
3305 if (is_error_reported()) return; // muzzle asserts when debugging an error
3306 if (Node::in_dump()) return; // muzzle asserts when printing
3307 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
3308 assert(n != NULL, "");
3309 // Elide intervening MergeMem's
3310 while (n->is_MergeMem()) {
3311 n = n->as_MergeMem()->memory_at(alias_idx);
3312 }
3313 Compile* C = Compile::current();
3314 const TypePtr* n_adr_type = n->adr_type();
3315 if (n == m->empty_memory()) {
3316 // Implicit copy of base_memory()
3317 } else if (n_adr_type != TypePtr::BOTTOM) {
3318 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type");
3319 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
3320 } else {
3321 // A few places like make_runtime_call "know" that VM calls are narrow,
3322 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
3323 bool expected_wide_mem = false;
3324 if (n == m->base_memory()) {
3325 expected_wide_mem = true;
3326 } else if (alias_idx == Compile::AliasIdxRaw ||
3327 n == m->memory_at(Compile::AliasIdxRaw)) {
3328 expected_wide_mem = true;
3329 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
3330 // memory can "leak through" calls on channels that
3331 // are write-once. Allow this also.
3332 expected_wide_mem = true;
3333 }
3334 assert(expected_wide_mem, "expected narrow slice replacement");
3335 }
3336 }
3337 #else // !ASSERT
3338 #define verify_memory_slice(m,i,n) (0) // PRODUCT version is no-op
3339 #endif
3340
3341
3342 //-----------------------------memory_at---------------------------------------
3343 Node* MergeMemNode::memory_at(uint alias_idx) const {
3344 assert(alias_idx >= Compile::AliasIdxRaw ||
3345 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0,
3346 "must avoid base_memory and AliasIdxTop");
3347
3348 // Otherwise, it is a narrow slice.
3349 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
3350 Compile *C = Compile::current();
3351 if (is_empty_memory(n)) {
3352 // the array is sparse; empty slots are the "top" node
3353 n = base_memory();
3354 assert(Node::in_dump()
3355 || n == NULL || n->bottom_type() == Type::TOP
3356 || n->adr_type() == TypePtr::BOTTOM
3357 || n->adr_type() == TypeRawPtr::BOTTOM
3358 || Compile::current()->AliasLevel() == 0,
3359 "must be a wide memory");
3360 // AliasLevel == 0 if we are organizing the memory states manually.
3361 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
3362 } else {
3363 // make sure the stored slice is sane
3364 #ifdef ASSERT
3365 if (is_error_reported() || Node::in_dump()) {
3366 } else if (might_be_same(n, base_memory())) {
3367 // Give it a pass: It is a mostly harmless repetition of the base.
3368 // This can arise normally from node subsumption during optimization.
3369 } else {
3370 verify_memory_slice(this, alias_idx, n);
3371 }
3372 #endif
3373 }
3374 return n;
3375 }
3376
3377 //---------------------------set_memory_at-------------------------------------
3378 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
3379 verify_memory_slice(this, alias_idx, n);
3380 Node* empty_mem = empty_memory();
3381 if (n == base_memory()) n = empty_mem; // collapse default
3382 uint need_req = alias_idx+1;
3383 if (req() < need_req) {
3384 if (n == empty_mem) return; // already the default, so do not grow me
3385 // grow the sparse array
3386 do {
3387 add_req(empty_mem);
3388 } while (req() < need_req);
3389 }
3390 set_req( alias_idx, n );
3391 }
3392
3393
3394
3395 //--------------------------iteration_setup------------------------------------
3396 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
3397 if (other != NULL) {
3398 grow_to_match(other);
3399 // invariant: the finite support of mm2 is within mm->req()
3400 #ifdef ASSERT
3401 for (uint i = req(); i < other->req(); i++) {
3402 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
3403 }
3404 #endif
3405 }
3406 // Replace spurious copies of base_memory by top.
3407 Node* base_mem = base_memory();
3408 if (base_mem != NULL && !base_mem->is_top()) {
3409 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
3410 if (in(i) == base_mem)
3411 set_req(i, empty_memory());
3412 }
3413 }
3414 }
3415
3416 //---------------------------grow_to_match-------------------------------------
3417 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
3418 Node* empty_mem = empty_memory();
3419 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
3420 // look for the finite support of the other memory
3421 for (uint i = other->req(); --i >= req(); ) {
3422 if (other->in(i) != empty_mem) {
3423 uint new_len = i+1;
3424 while (req() < new_len) add_req(empty_mem);
3425 break;
3426 }
3427 }
3428 }
3429
3430 //---------------------------verify_sparse-------------------------------------
3431 #ifndef PRODUCT
3432 bool MergeMemNode::verify_sparse() const {
3433 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
3434 Node* base_mem = base_memory();
3435 // The following can happen in degenerate cases, since empty==top.
3436 if (is_empty_memory(base_mem)) return true;
3437 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3438 assert(in(i) != NULL, "sane slice");
3439 if (in(i) == base_mem) return false; // should have been the sentinel value!
3440 }
3441 return true;
3442 }
3443
3444 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
3445 Node* n;
3446 n = mm->in(idx);
3447 if (mem == n) return true; // might be empty_memory()
3448 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
3449 if (mem == n) return true;
3450 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) {
3451 if (mem == n) return true;
3452 if (n == NULL) break;
3453 }
3454 return false;
3455 }
3456 #endif // !PRODUCT