Sun, 13 Apr 2008 17:43:42 -0400
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
Summary: Compressed oops in instances, arrays, and headers. Code contributors are coleenp, phh, never, swamyv
Reviewed-by: jmasa, kamg, acorn, tbell, kvn, rasbold
1 /*
2 * Copyright 1997-2007 Sun Microsystems, Inc. All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
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7 * published by the Free Software Foundation.
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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13 * accompanied this code).
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15 * You should have received a copy of the GNU General Public License version
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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23 */
25 // Portions of code courtesy of Clifford Click
27 // Optimization - Graph Style
29 #include "incls/_precompiled.incl"
30 #include "incls/_memnode.cpp.incl"
32 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st);
34 //=============================================================================
35 uint MemNode::size_of() const { return sizeof(*this); }
37 const TypePtr *MemNode::adr_type() const {
38 Node* adr = in(Address);
39 const TypePtr* cross_check = NULL;
40 DEBUG_ONLY(cross_check = _adr_type);
41 return calculate_adr_type(adr->bottom_type(), cross_check);
42 }
44 #ifndef PRODUCT
45 void MemNode::dump_spec(outputStream *st) const {
46 if (in(Address) == NULL) return; // node is dead
47 #ifndef ASSERT
48 // fake the missing field
49 const TypePtr* _adr_type = NULL;
50 if (in(Address) != NULL)
51 _adr_type = in(Address)->bottom_type()->isa_ptr();
52 #endif
53 dump_adr_type(this, _adr_type, st);
55 Compile* C = Compile::current();
56 if( C->alias_type(_adr_type)->is_volatile() )
57 st->print(" Volatile!");
58 }
60 void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) {
61 st->print(" @");
62 if (adr_type == NULL) {
63 st->print("NULL");
64 } else {
65 adr_type->dump_on(st);
66 Compile* C = Compile::current();
67 Compile::AliasType* atp = NULL;
68 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type);
69 if (atp == NULL)
70 st->print(", idx=?\?;");
71 else if (atp->index() == Compile::AliasIdxBot)
72 st->print(", idx=Bot;");
73 else if (atp->index() == Compile::AliasIdxTop)
74 st->print(", idx=Top;");
75 else if (atp->index() == Compile::AliasIdxRaw)
76 st->print(", idx=Raw;");
77 else {
78 ciField* field = atp->field();
79 if (field) {
80 st->print(", name=");
81 field->print_name_on(st);
82 }
83 st->print(", idx=%d;", atp->index());
84 }
85 }
86 }
88 extern void print_alias_types();
90 #endif
92 Node *MemNode::optimize_simple_memory_chain(Node *mchain, const TypePtr *t_adr, PhaseGVN *phase) {
93 const TypeOopPtr *tinst = t_adr->isa_oopptr();
94 if (tinst == NULL || !tinst->is_instance_field())
95 return mchain; // don't try to optimize non-instance types
96 uint instance_id = tinst->instance_id();
97 Node *prev = NULL;
98 Node *result = mchain;
99 while (prev != result) {
100 prev = result;
101 // skip over a call which does not affect this memory slice
102 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {
103 Node *proj_in = result->in(0);
104 if (proj_in->is_Call()) {
105 CallNode *call = proj_in->as_Call();
106 if (!call->may_modify(t_adr, phase)) {
107 result = call->in(TypeFunc::Memory);
108 }
109 } else if (proj_in->is_Initialize()) {
110 AllocateNode* alloc = proj_in->as_Initialize()->allocation();
111 // Stop if this is the initialization for the object instance which
112 // which contains this memory slice, otherwise skip over it.
113 if (alloc != NULL && alloc->_idx != instance_id) {
114 result = proj_in->in(TypeFunc::Memory);
115 }
116 } else if (proj_in->is_MemBar()) {
117 result = proj_in->in(TypeFunc::Memory);
118 }
119 } else if (result->is_MergeMem()) {
120 result = step_through_mergemem(phase, result->as_MergeMem(), t_adr, NULL, tty);
121 }
122 }
123 return result;
124 }
126 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, PhaseGVN *phase) {
127 const TypeOopPtr *t_oop = t_adr->isa_oopptr();
128 bool is_instance = (t_oop != NULL) && t_oop->is_instance_field();
129 PhaseIterGVN *igvn = phase->is_IterGVN();
130 Node *result = mchain;
131 result = optimize_simple_memory_chain(result, t_adr, phase);
132 if (is_instance && igvn != NULL && result->is_Phi()) {
133 PhiNode *mphi = result->as_Phi();
134 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
135 const TypePtr *t = mphi->adr_type();
136 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM) {
137 // clone the Phi with our address type
138 result = mphi->split_out_instance(t_adr, igvn);
139 } else {
140 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain");
141 }
142 }
143 return result;
144 }
146 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) {
147 uint alias_idx = phase->C->get_alias_index(tp);
148 Node *mem = mmem;
149 #ifdef ASSERT
150 {
151 // Check that current type is consistent with the alias index used during graph construction
152 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
153 bool consistent = adr_check == NULL || adr_check->empty() ||
154 phase->C->must_alias(adr_check, alias_idx );
155 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
156 if( !consistent && adr_check != NULL && !adr_check->empty() &&
157 tp->isa_aryptr() && tp->offset() == Type::OffsetBot &&
158 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot &&
159 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() ||
160 adr_check->offset() == oopDesc::klass_offset_in_bytes() ||
161 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) {
162 // don't assert if it is dead code.
163 consistent = true;
164 }
165 if( !consistent ) {
166 st->print("alias_idx==%d, adr_check==", alias_idx);
167 if( adr_check == NULL ) {
168 st->print("NULL");
169 } else {
170 adr_check->dump();
171 }
172 st->cr();
173 print_alias_types();
174 assert(consistent, "adr_check must match alias idx");
175 }
176 }
177 #endif
178 // TypeInstPtr::NOTNULL+any is an OOP with unknown offset - generally
179 // means an array I have not precisely typed yet. Do not do any
180 // alias stuff with it any time soon.
181 const TypeOopPtr *tinst = tp->isa_oopptr();
182 if( tp->base() != Type::AnyPtr &&
183 !(tinst &&
184 tinst->klass()->is_java_lang_Object() &&
185 tinst->offset() == Type::OffsetBot) ) {
186 // compress paths and change unreachable cycles to TOP
187 // If not, we can update the input infinitely along a MergeMem cycle
188 // Equivalent code in PhiNode::Ideal
189 Node* m = phase->transform(mmem);
190 // If tranformed to a MergeMem, get the desired slice
191 // Otherwise the returned node represents memory for every slice
192 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
193 // Update input if it is progress over what we have now
194 }
195 return mem;
196 }
198 //--------------------------Ideal_common---------------------------------------
199 // Look for degenerate control and memory inputs. Bypass MergeMem inputs.
200 // Unhook non-raw memories from complete (macro-expanded) initializations.
201 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
202 // If our control input is a dead region, kill all below the region
203 Node *ctl = in(MemNode::Control);
204 if (ctl && remove_dead_region(phase, can_reshape))
205 return this;
207 // Ignore if memory is dead, or self-loop
208 Node *mem = in(MemNode::Memory);
209 if( phase->type( mem ) == Type::TOP ) return NodeSentinel; // caller will return NULL
210 assert( mem != this, "dead loop in MemNode::Ideal" );
212 Node *address = in(MemNode::Address);
213 const Type *t_adr = phase->type( address );
214 if( t_adr == Type::TOP ) return NodeSentinel; // caller will return NULL
216 // Avoid independent memory operations
217 Node* old_mem = mem;
219 // The code which unhooks non-raw memories from complete (macro-expanded)
220 // initializations was removed. After macro-expansion all stores catched
221 // by Initialize node became raw stores and there is no information
222 // which memory slices they modify. So it is unsafe to move any memory
223 // operation above these stores. Also in most cases hooked non-raw memories
224 // were already unhooked by using information from detect_ptr_independence()
225 // and find_previous_store().
227 if (mem->is_MergeMem()) {
228 MergeMemNode* mmem = mem->as_MergeMem();
229 const TypePtr *tp = t_adr->is_ptr();
231 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
232 }
234 if (mem != old_mem) {
235 set_req(MemNode::Memory, mem);
236 return this;
237 }
239 // let the subclass continue analyzing...
240 return NULL;
241 }
243 // Helper function for proving some simple control dominations.
244 // Attempt to prove that control input 'dom' dominates (or equals) 'sub'.
245 // Already assumes that 'dom' is available at 'sub', and that 'sub'
246 // is not a constant (dominated by the method's StartNode).
247 // Used by MemNode::find_previous_store to prove that the
248 // control input of a memory operation predates (dominates)
249 // an allocation it wants to look past.
250 bool MemNode::detect_dominating_control(Node* dom, Node* sub) {
251 if (dom == NULL) return false;
252 if (dom->is_Proj()) dom = dom->in(0);
253 if (dom->is_Start()) return true; // anything inside the method
254 if (dom->is_Root()) return true; // dom 'controls' a constant
255 int cnt = 20; // detect cycle or too much effort
256 while (sub != NULL) { // walk 'sub' up the chain to 'dom'
257 if (--cnt < 0) return false; // in a cycle or too complex
258 if (sub == dom) return true;
259 if (sub->is_Start()) return false;
260 if (sub->is_Root()) return false;
261 Node* up = sub->in(0);
262 if (sub == up && sub->is_Region()) {
263 for (uint i = 1; i < sub->req(); i++) {
264 Node* in = sub->in(i);
265 if (in != NULL && !in->is_top() && in != sub) {
266 up = in; break; // take any path on the way up to 'dom'
267 }
268 }
269 }
270 if (sub == up) return false; // some kind of tight cycle
271 sub = up;
272 }
273 return false;
274 }
276 //---------------------detect_ptr_independence---------------------------------
277 // Used by MemNode::find_previous_store to prove that two base
278 // pointers are never equal.
279 // The pointers are accompanied by their associated allocations,
280 // if any, which have been previously discovered by the caller.
281 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
282 Node* p2, AllocateNode* a2,
283 PhaseTransform* phase) {
284 // Attempt to prove that these two pointers cannot be aliased.
285 // They may both manifestly be allocations, and they should differ.
286 // Or, if they are not both allocations, they can be distinct constants.
287 // Otherwise, one is an allocation and the other a pre-existing value.
288 if (a1 == NULL && a2 == NULL) { // neither an allocation
289 return (p1 != p2) && p1->is_Con() && p2->is_Con();
290 } else if (a1 != NULL && a2 != NULL) { // both allocations
291 return (a1 != a2);
292 } else if (a1 != NULL) { // one allocation a1
293 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.)
294 return detect_dominating_control(p2->in(0), a1->in(0));
295 } else { //(a2 != NULL) // one allocation a2
296 return detect_dominating_control(p1->in(0), a2->in(0));
297 }
298 return false;
299 }
302 // The logic for reordering loads and stores uses four steps:
303 // (a) Walk carefully past stores and initializations which we
304 // can prove are independent of this load.
305 // (b) Observe that the next memory state makes an exact match
306 // with self (load or store), and locate the relevant store.
307 // (c) Ensure that, if we were to wire self directly to the store,
308 // the optimizer would fold it up somehow.
309 // (d) Do the rewiring, and return, depending on some other part of
310 // the optimizer to fold up the load.
311 // This routine handles steps (a) and (b). Steps (c) and (d) are
312 // specific to loads and stores, so they are handled by the callers.
313 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.)
314 //
315 Node* MemNode::find_previous_store(PhaseTransform* phase) {
316 Node* ctrl = in(MemNode::Control);
317 Node* adr = in(MemNode::Address);
318 intptr_t offset = 0;
319 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
320 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase);
322 if (offset == Type::OffsetBot)
323 return NULL; // cannot unalias unless there are precise offsets
325 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr();
327 intptr_t size_in_bytes = memory_size();
329 Node* mem = in(MemNode::Memory); // start searching here...
331 int cnt = 50; // Cycle limiter
332 for (;;) { // While we can dance past unrelated stores...
333 if (--cnt < 0) break; // Caught in cycle or a complicated dance?
335 if (mem->is_Store()) {
336 Node* st_adr = mem->in(MemNode::Address);
337 intptr_t st_offset = 0;
338 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
339 if (st_base == NULL)
340 break; // inscrutable pointer
341 if (st_offset != offset && st_offset != Type::OffsetBot) {
342 const int MAX_STORE = BytesPerLong;
343 if (st_offset >= offset + size_in_bytes ||
344 st_offset <= offset - MAX_STORE ||
345 st_offset <= offset - mem->as_Store()->memory_size()) {
346 // Success: The offsets are provably independent.
347 // (You may ask, why not just test st_offset != offset and be done?
348 // The answer is that stores of different sizes can co-exist
349 // in the same sequence of RawMem effects. We sometimes initialize
350 // a whole 'tile' of array elements with a single jint or jlong.)
351 mem = mem->in(MemNode::Memory);
352 continue; // (a) advance through independent store memory
353 }
354 }
355 if (st_base != base &&
356 detect_ptr_independence(base, alloc,
357 st_base,
358 AllocateNode::Ideal_allocation(st_base, phase),
359 phase)) {
360 // Success: The bases are provably independent.
361 mem = mem->in(MemNode::Memory);
362 continue; // (a) advance through independent store memory
363 }
365 // (b) At this point, if the bases or offsets do not agree, we lose,
366 // since we have not managed to prove 'this' and 'mem' independent.
367 if (st_base == base && st_offset == offset) {
368 return mem; // let caller handle steps (c), (d)
369 }
371 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
372 InitializeNode* st_init = mem->in(0)->as_Initialize();
373 AllocateNode* st_alloc = st_init->allocation();
374 if (st_alloc == NULL)
375 break; // something degenerated
376 bool known_identical = false;
377 bool known_independent = false;
378 if (alloc == st_alloc)
379 known_identical = true;
380 else if (alloc != NULL)
381 known_independent = true;
382 else if (ctrl != NULL &&
383 detect_dominating_control(ctrl, st_alloc->in(0)))
384 known_independent = true;
386 if (known_independent) {
387 // The bases are provably independent: Either they are
388 // manifestly distinct allocations, or else the control
389 // of this load dominates the store's allocation.
390 int alias_idx = phase->C->get_alias_index(adr_type());
391 if (alias_idx == Compile::AliasIdxRaw) {
392 mem = st_alloc->in(TypeFunc::Memory);
393 } else {
394 mem = st_init->memory(alias_idx);
395 }
396 continue; // (a) advance through independent store memory
397 }
399 // (b) at this point, if we are not looking at a store initializing
400 // the same allocation we are loading from, we lose.
401 if (known_identical) {
402 // From caller, can_see_stored_value will consult find_captured_store.
403 return mem; // let caller handle steps (c), (d)
404 }
406 } else if (addr_t != NULL && addr_t->is_instance_field()) {
407 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
408 if (mem->is_Proj() && mem->in(0)->is_Call()) {
409 CallNode *call = mem->in(0)->as_Call();
410 if (!call->may_modify(addr_t, phase)) {
411 mem = call->in(TypeFunc::Memory);
412 continue; // (a) advance through independent call memory
413 }
414 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) {
415 mem = mem->in(0)->in(TypeFunc::Memory);
416 continue; // (a) advance through independent MemBar memory
417 } else if (mem->is_MergeMem()) {
418 int alias_idx = phase->C->get_alias_index(adr_type());
419 mem = mem->as_MergeMem()->memory_at(alias_idx);
420 continue; // (a) advance through independent MergeMem memory
421 }
422 }
424 // Unless there is an explicit 'continue', we must bail out here,
425 // because 'mem' is an inscrutable memory state (e.g., a call).
426 break;
427 }
429 return NULL; // bail out
430 }
432 //----------------------calculate_adr_type-------------------------------------
433 // Helper function. Notices when the given type of address hits top or bottom.
434 // Also, asserts a cross-check of the type against the expected address type.
435 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
436 if (t == Type::TOP) return NULL; // does not touch memory any more?
437 #ifdef PRODUCT
438 cross_check = NULL;
439 #else
440 if (!VerifyAliases || is_error_reported() || Node::in_dump()) cross_check = NULL;
441 #endif
442 const TypePtr* tp = t->isa_ptr();
443 if (tp == NULL) {
444 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
445 return TypePtr::BOTTOM; // touches lots of memory
446 } else {
447 #ifdef ASSERT
448 // %%%% [phh] We don't check the alias index if cross_check is
449 // TypeRawPtr::BOTTOM. Needs to be investigated.
450 if (cross_check != NULL &&
451 cross_check != TypePtr::BOTTOM &&
452 cross_check != TypeRawPtr::BOTTOM) {
453 // Recheck the alias index, to see if it has changed (due to a bug).
454 Compile* C = Compile::current();
455 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
456 "must stay in the original alias category");
457 // The type of the address must be contained in the adr_type,
458 // disregarding "null"-ness.
459 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
460 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
461 assert(cross_check->meet(tp_notnull) == cross_check,
462 "real address must not escape from expected memory type");
463 }
464 #endif
465 return tp;
466 }
467 }
469 //------------------------adr_phi_is_loop_invariant----------------------------
470 // A helper function for Ideal_DU_postCCP to check if a Phi in a counted
471 // loop is loop invariant. Make a quick traversal of Phi and associated
472 // CastPP nodes, looking to see if they are a closed group within the loop.
473 bool MemNode::adr_phi_is_loop_invariant(Node* adr_phi, Node* cast) {
474 // The idea is that the phi-nest must boil down to only CastPP nodes
475 // with the same data. This implies that any path into the loop already
476 // includes such a CastPP, and so the original cast, whatever its input,
477 // must be covered by an equivalent cast, with an earlier control input.
478 ResourceMark rm;
480 // The loop entry input of the phi should be the unique dominating
481 // node for every Phi/CastPP in the loop.
482 Unique_Node_List closure;
483 closure.push(adr_phi->in(LoopNode::EntryControl));
485 // Add the phi node and the cast to the worklist.
486 Unique_Node_List worklist;
487 worklist.push(adr_phi);
488 if( cast != NULL ){
489 if( !cast->is_ConstraintCast() ) return false;
490 worklist.push(cast);
491 }
493 // Begin recursive walk of phi nodes.
494 while( worklist.size() ){
495 // Take a node off the worklist
496 Node *n = worklist.pop();
497 if( !closure.member(n) ){
498 // Add it to the closure.
499 closure.push(n);
500 // Make a sanity check to ensure we don't waste too much time here.
501 if( closure.size() > 20) return false;
502 // This node is OK if:
503 // - it is a cast of an identical value
504 // - or it is a phi node (then we add its inputs to the worklist)
505 // Otherwise, the node is not OK, and we presume the cast is not invariant
506 if( n->is_ConstraintCast() ){
507 worklist.push(n->in(1));
508 } else if( n->is_Phi() ) {
509 for( uint i = 1; i < n->req(); i++ ) {
510 worklist.push(n->in(i));
511 }
512 } else {
513 return false;
514 }
515 }
516 }
518 // Quit when the worklist is empty, and we've found no offending nodes.
519 return true;
520 }
522 //------------------------------Ideal_DU_postCCP-------------------------------
523 // Find any cast-away of null-ness and keep its control. Null cast-aways are
524 // going away in this pass and we need to make this memory op depend on the
525 // gating null check.
527 // I tried to leave the CastPP's in. This makes the graph more accurate in
528 // some sense; we get to keep around the knowledge that an oop is not-null
529 // after some test. Alas, the CastPP's interfere with GVN (some values are
530 // the regular oop, some are the CastPP of the oop, all merge at Phi's which
531 // cannot collapse, etc). This cost us 10% on SpecJVM, even when I removed
532 // some of the more trivial cases in the optimizer. Removing more useless
533 // Phi's started allowing Loads to illegally float above null checks. I gave
534 // up on this approach. CNC 10/20/2000
535 Node *MemNode::Ideal_DU_postCCP( PhaseCCP *ccp ) {
536 Node *ctr = in(MemNode::Control);
537 Node *mem = in(MemNode::Memory);
538 Node *adr = in(MemNode::Address);
539 Node *skipped_cast = NULL;
540 // Need a null check? Regular static accesses do not because they are
541 // from constant addresses. Array ops are gated by the range check (which
542 // always includes a NULL check). Just check field ops.
543 if( !ctr ) {
544 // Scan upwards for the highest location we can place this memory op.
545 while( true ) {
546 switch( adr->Opcode() ) {
548 case Op_AddP: // No change to NULL-ness, so peek thru AddP's
549 adr = adr->in(AddPNode::Base);
550 continue;
552 case Op_DecodeN: // No change to NULL-ness, so peek thru
553 adr = adr->in(1);
554 continue;
556 case Op_CastPP:
557 // If the CastPP is useless, just peek on through it.
558 if( ccp->type(adr) == ccp->type(adr->in(1)) ) {
559 // Remember the cast that we've peeked though. If we peek
560 // through more than one, then we end up remembering the highest
561 // one, that is, if in a loop, the one closest to the top.
562 skipped_cast = adr;
563 adr = adr->in(1);
564 continue;
565 }
566 // CastPP is going away in this pass! We need this memory op to be
567 // control-dependent on the test that is guarding the CastPP.
568 ccp->hash_delete(this);
569 set_req(MemNode::Control, adr->in(0));
570 ccp->hash_insert(this);
571 return this;
573 case Op_Phi:
574 // Attempt to float above a Phi to some dominating point.
575 if (adr->in(0) != NULL && adr->in(0)->is_CountedLoop()) {
576 // If we've already peeked through a Cast (which could have set the
577 // control), we can't float above a Phi, because the skipped Cast
578 // may not be loop invariant.
579 if (adr_phi_is_loop_invariant(adr, skipped_cast)) {
580 adr = adr->in(1);
581 continue;
582 }
583 }
585 // Intentional fallthrough!
587 // No obvious dominating point. The mem op is pinned below the Phi
588 // by the Phi itself. If the Phi goes away (no true value is merged)
589 // then the mem op can float, but not indefinitely. It must be pinned
590 // behind the controls leading to the Phi.
591 case Op_CheckCastPP:
592 // These usually stick around to change address type, however a
593 // useless one can be elided and we still need to pick up a control edge
594 if (adr->in(0) == NULL) {
595 // This CheckCastPP node has NO control and is likely useless. But we
596 // need check further up the ancestor chain for a control input to keep
597 // the node in place. 4959717.
598 skipped_cast = adr;
599 adr = adr->in(1);
600 continue;
601 }
602 ccp->hash_delete(this);
603 set_req(MemNode::Control, adr->in(0));
604 ccp->hash_insert(this);
605 return this;
607 // List of "safe" opcodes; those that implicitly block the memory
608 // op below any null check.
609 case Op_CastX2P: // no null checks on native pointers
610 case Op_Parm: // 'this' pointer is not null
611 case Op_LoadP: // Loading from within a klass
612 case Op_LoadN: // Loading from within a klass
613 case Op_LoadKlass: // Loading from within a klass
614 case Op_ConP: // Loading from a klass
615 case Op_CreateEx: // Sucking up the guts of an exception oop
616 case Op_Con: // Reading from TLS
617 case Op_CMoveP: // CMoveP is pinned
618 break; // No progress
620 case Op_Proj: // Direct call to an allocation routine
621 case Op_SCMemProj: // Memory state from store conditional ops
622 #ifdef ASSERT
623 {
624 assert(adr->as_Proj()->_con == TypeFunc::Parms, "must be return value");
625 const Node* call = adr->in(0);
626 if (call->is_CallStaticJava()) {
627 const CallStaticJavaNode* call_java = call->as_CallStaticJava();
628 const TypeTuple *r = call_java->tf()->range();
629 assert(r->cnt() > TypeFunc::Parms, "must return value");
630 const Type* ret_type = r->field_at(TypeFunc::Parms);
631 assert(ret_type && ret_type->isa_ptr(), "must return pointer");
632 // We further presume that this is one of
633 // new_instance_Java, new_array_Java, or
634 // the like, but do not assert for this.
635 } else if (call->is_Allocate()) {
636 // similar case to new_instance_Java, etc.
637 } else if (!call->is_CallLeaf()) {
638 // Projections from fetch_oop (OSR) are allowed as well.
639 ShouldNotReachHere();
640 }
641 }
642 #endif
643 break;
644 default:
645 ShouldNotReachHere();
646 }
647 break;
648 }
649 }
651 return NULL; // No progress
652 }
655 //=============================================================================
656 uint LoadNode::size_of() const { return sizeof(*this); }
657 uint LoadNode::cmp( const Node &n ) const
658 { return !Type::cmp( _type, ((LoadNode&)n)._type ); }
659 const Type *LoadNode::bottom_type() const { return _type; }
660 uint LoadNode::ideal_reg() const {
661 return Matcher::base2reg[_type->base()];
662 }
664 #ifndef PRODUCT
665 void LoadNode::dump_spec(outputStream *st) const {
666 MemNode::dump_spec(st);
667 if( !Verbose && !WizardMode ) {
668 // standard dump does this in Verbose and WizardMode
669 st->print(" #"); _type->dump_on(st);
670 }
671 }
672 #endif
675 //----------------------------LoadNode::make-----------------------------------
676 // Polymorphic factory method:
677 Node *LoadNode::make( PhaseGVN& gvn, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt ) {
678 Compile* C = gvn.C;
680 // sanity check the alias category against the created node type
681 assert(!(adr_type->isa_oopptr() &&
682 adr_type->offset() == oopDesc::klass_offset_in_bytes()),
683 "use LoadKlassNode instead");
684 assert(!(adr_type->isa_aryptr() &&
685 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
686 "use LoadRangeNode instead");
687 switch (bt) {
688 case T_BOOLEAN:
689 case T_BYTE: return new (C, 3) LoadBNode(ctl, mem, adr, adr_type, rt->is_int() );
690 case T_INT: return new (C, 3) LoadINode(ctl, mem, adr, adr_type, rt->is_int() );
691 case T_CHAR: return new (C, 3) LoadCNode(ctl, mem, adr, adr_type, rt->is_int() );
692 case T_SHORT: return new (C, 3) LoadSNode(ctl, mem, adr, adr_type, rt->is_int() );
693 case T_LONG: return new (C, 3) LoadLNode(ctl, mem, adr, adr_type, rt->is_long() );
694 case T_FLOAT: return new (C, 3) LoadFNode(ctl, mem, adr, adr_type, rt );
695 case T_DOUBLE: return new (C, 3) LoadDNode(ctl, mem, adr, adr_type, rt );
696 case T_ADDRESS: return new (C, 3) LoadPNode(ctl, mem, adr, adr_type, rt->is_ptr() );
697 case T_OBJECT:
698 #ifdef _LP64
699 if (adr->bottom_type()->is_narrow()) {
700 const TypeNarrowOop* narrowtype;
701 if (rt->isa_narrowoop()) {
702 narrowtype = rt->is_narrowoop();
703 rt = narrowtype->make_oopptr();
704 } else {
705 narrowtype = rt->is_oopptr()->make_narrowoop();
706 }
707 Node* load = gvn.transform(new (C, 3) LoadNNode(ctl, mem, adr, adr_type, narrowtype));
709 return new (C, 2) DecodeNNode(load, rt);
710 } else
711 #endif
712 {
713 assert(!adr->bottom_type()->is_narrow(), "should have got back a narrow oop");
714 return new (C, 3) LoadPNode(ctl, mem, adr, adr_type, rt->is_oopptr());
715 }
716 }
717 ShouldNotReachHere();
718 return (LoadNode*)NULL;
719 }
721 LoadLNode* LoadLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt) {
722 bool require_atomic = true;
723 return new (C, 3) LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), require_atomic);
724 }
729 //------------------------------hash-------------------------------------------
730 uint LoadNode::hash() const {
731 // unroll addition of interesting fields
732 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
733 }
735 //---------------------------can_see_stored_value------------------------------
736 // This routine exists to make sure this set of tests is done the same
737 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
738 // will change the graph shape in a way which makes memory alive twice at the
739 // same time (uses the Oracle model of aliasing), then some
740 // LoadXNode::Identity will fold things back to the equivalence-class model
741 // of aliasing.
742 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const {
743 Node* ld_adr = in(MemNode::Address);
745 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
746 Compile::AliasType* atp = tp != NULL ? phase->C->alias_type(tp) : NULL;
747 if (EliminateAutoBox && atp != NULL && atp->index() >= Compile::AliasIdxRaw &&
748 atp->field() != NULL && !atp->field()->is_volatile()) {
749 uint alias_idx = atp->index();
750 bool final = atp->field()->is_final();
751 Node* result = NULL;
752 Node* current = st;
753 // Skip through chains of MemBarNodes checking the MergeMems for
754 // new states for the slice of this load. Stop once any other
755 // kind of node is encountered. Loads from final memory can skip
756 // through any kind of MemBar but normal loads shouldn't skip
757 // through MemBarAcquire since the could allow them to move out of
758 // a synchronized region.
759 while (current->is_Proj()) {
760 int opc = current->in(0)->Opcode();
761 if ((final && opc == Op_MemBarAcquire) ||
762 opc == Op_MemBarRelease || opc == Op_MemBarCPUOrder) {
763 Node* mem = current->in(0)->in(TypeFunc::Memory);
764 if (mem->is_MergeMem()) {
765 MergeMemNode* merge = mem->as_MergeMem();
766 Node* new_st = merge->memory_at(alias_idx);
767 if (new_st == merge->base_memory()) {
768 // Keep searching
769 current = merge->base_memory();
770 continue;
771 }
772 // Save the new memory state for the slice and fall through
773 // to exit.
774 result = new_st;
775 }
776 }
777 break;
778 }
779 if (result != NULL) {
780 st = result;
781 }
782 }
785 // Loop around twice in the case Load -> Initialize -> Store.
786 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
787 for (int trip = 0; trip <= 1; trip++) {
789 if (st->is_Store()) {
790 Node* st_adr = st->in(MemNode::Address);
791 if (!phase->eqv(st_adr, ld_adr)) {
792 // Try harder before giving up... Match raw and non-raw pointers.
793 intptr_t st_off = 0;
794 AllocateNode* alloc = AllocateNode::Ideal_allocation(st_adr, phase, st_off);
795 if (alloc == NULL) return NULL;
796 intptr_t ld_off = 0;
797 AllocateNode* allo2 = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
798 if (alloc != allo2) return NULL;
799 if (ld_off != st_off) return NULL;
800 // At this point we have proven something like this setup:
801 // A = Allocate(...)
802 // L = LoadQ(, AddP(CastPP(, A.Parm),, #Off))
803 // S = StoreQ(, AddP(, A.Parm , #Off), V)
804 // (Actually, we haven't yet proven the Q's are the same.)
805 // In other words, we are loading from a casted version of
806 // the same pointer-and-offset that we stored to.
807 // Thus, we are able to replace L by V.
808 }
809 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
810 if (store_Opcode() != st->Opcode())
811 return NULL;
812 return st->in(MemNode::ValueIn);
813 }
815 intptr_t offset = 0; // scratch
817 // A load from a freshly-created object always returns zero.
818 // (This can happen after LoadNode::Ideal resets the load's memory input
819 // to find_captured_store, which returned InitializeNode::zero_memory.)
820 if (st->is_Proj() && st->in(0)->is_Allocate() &&
821 st->in(0) == AllocateNode::Ideal_allocation(ld_adr, phase, offset) &&
822 offset >= st->in(0)->as_Allocate()->minimum_header_size()) {
823 // return a zero value for the load's basic type
824 // (This is one of the few places where a generic PhaseTransform
825 // can create new nodes. Think of it as lazily manifesting
826 // virtually pre-existing constants.)
827 return phase->zerocon(memory_type());
828 }
830 // A load from an initialization barrier can match a captured store.
831 if (st->is_Proj() && st->in(0)->is_Initialize()) {
832 InitializeNode* init = st->in(0)->as_Initialize();
833 AllocateNode* alloc = init->allocation();
834 if (alloc != NULL &&
835 alloc == AllocateNode::Ideal_allocation(ld_adr, phase, offset)) {
836 // examine a captured store value
837 st = init->find_captured_store(offset, memory_size(), phase);
838 if (st != NULL)
839 continue; // take one more trip around
840 }
841 }
843 break;
844 }
846 return NULL;
847 }
849 //----------------------is_instance_field_load_with_local_phi------------------
850 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
851 if( in(MemNode::Memory)->is_Phi() && in(MemNode::Memory)->in(0) == ctrl &&
852 in(MemNode::Address)->is_AddP() ) {
853 const TypeOopPtr* t_oop = in(MemNode::Address)->bottom_type()->isa_oopptr();
854 // Only instances.
855 if( t_oop != NULL && t_oop->is_instance_field() &&
856 t_oop->offset() != Type::OffsetBot &&
857 t_oop->offset() != Type::OffsetTop) {
858 return true;
859 }
860 }
861 return false;
862 }
864 //------------------------------Identity---------------------------------------
865 // Loads are identity if previous store is to same address
866 Node *LoadNode::Identity( PhaseTransform *phase ) {
867 // If the previous store-maker is the right kind of Store, and the store is
868 // to the same address, then we are equal to the value stored.
869 Node* mem = in(MemNode::Memory);
870 Node* value = can_see_stored_value(mem, phase);
871 if( value ) {
872 // byte, short & char stores truncate naturally.
873 // A load has to load the truncated value which requires
874 // some sort of masking operation and that requires an
875 // Ideal call instead of an Identity call.
876 if (memory_size() < BytesPerInt) {
877 // If the input to the store does not fit with the load's result type,
878 // it must be truncated via an Ideal call.
879 if (!phase->type(value)->higher_equal(phase->type(this)))
880 return this;
881 }
882 // (This works even when value is a Con, but LoadNode::Value
883 // usually runs first, producing the singleton type of the Con.)
884 return value;
885 }
887 // Search for an existing data phi which was generated before for the same
888 // instance's field to avoid infinite genertion of phis in a loop.
889 Node *region = mem->in(0);
890 if (is_instance_field_load_with_local_phi(region)) {
891 const TypePtr *addr_t = in(MemNode::Address)->bottom_type()->isa_ptr();
892 int this_index = phase->C->get_alias_index(addr_t);
893 int this_offset = addr_t->offset();
894 int this_id = addr_t->is_oopptr()->instance_id();
895 const Type* this_type = bottom_type();
896 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
897 Node* phi = region->fast_out(i);
898 if (phi->is_Phi() && phi != mem &&
899 phi->as_Phi()->is_same_inst_field(this_type, this_id, this_index, this_offset)) {
900 return phi;
901 }
902 }
903 }
905 return this;
906 }
909 // Returns true if the AliasType refers to the field that holds the
910 // cached box array. Currently only handles the IntegerCache case.
911 static bool is_autobox_cache(Compile::AliasType* atp) {
912 if (atp != NULL && atp->field() != NULL) {
913 ciField* field = atp->field();
914 ciSymbol* klass = field->holder()->name();
915 if (field->name() == ciSymbol::cache_field_name() &&
916 field->holder()->uses_default_loader() &&
917 klass == ciSymbol::java_lang_Integer_IntegerCache()) {
918 return true;
919 }
920 }
921 return false;
922 }
924 // Fetch the base value in the autobox array
925 static bool fetch_autobox_base(Compile::AliasType* atp, int& cache_offset) {
926 if (atp != NULL && atp->field() != NULL) {
927 ciField* field = atp->field();
928 ciSymbol* klass = field->holder()->name();
929 if (field->name() == ciSymbol::cache_field_name() &&
930 field->holder()->uses_default_loader() &&
931 klass == ciSymbol::java_lang_Integer_IntegerCache()) {
932 assert(field->is_constant(), "what?");
933 ciObjArray* array = field->constant_value().as_object()->as_obj_array();
934 // Fetch the box object at the base of the array and get its value
935 ciInstance* box = array->obj_at(0)->as_instance();
936 ciInstanceKlass* ik = box->klass()->as_instance_klass();
937 if (ik->nof_nonstatic_fields() == 1) {
938 // This should be true nonstatic_field_at requires calling
939 // nof_nonstatic_fields so check it anyway
940 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
941 cache_offset = c.as_int();
942 }
943 return true;
944 }
945 }
946 return false;
947 }
949 // Returns true if the AliasType refers to the value field of an
950 // autobox object. Currently only handles Integer.
951 static bool is_autobox_object(Compile::AliasType* atp) {
952 if (atp != NULL && atp->field() != NULL) {
953 ciField* field = atp->field();
954 ciSymbol* klass = field->holder()->name();
955 if (field->name() == ciSymbol::value_name() &&
956 field->holder()->uses_default_loader() &&
957 klass == ciSymbol::java_lang_Integer()) {
958 return true;
959 }
960 }
961 return false;
962 }
965 // We're loading from an object which has autobox behaviour.
966 // If this object is result of a valueOf call we'll have a phi
967 // merging a newly allocated object and a load from the cache.
968 // We want to replace this load with the original incoming
969 // argument to the valueOf call.
970 Node* LoadNode::eliminate_autobox(PhaseGVN* phase) {
971 Node* base = in(Address)->in(AddPNode::Base);
972 if (base->is_Phi() && base->req() == 3) {
973 AllocateNode* allocation = NULL;
974 int allocation_index = -1;
975 int load_index = -1;
976 for (uint i = 1; i < base->req(); i++) {
977 allocation = AllocateNode::Ideal_allocation(base->in(i), phase);
978 if (allocation != NULL) {
979 allocation_index = i;
980 load_index = 3 - allocation_index;
981 break;
982 }
983 }
984 LoadNode* load = NULL;
985 if (allocation != NULL && base->in(load_index)->is_Load()) {
986 load = base->in(load_index)->as_Load();
987 }
988 if (load != NULL && in(Memory)->is_Phi() && in(Memory)->in(0) == base->in(0)) {
989 // Push the loads from the phi that comes from valueOf up
990 // through it to allow elimination of the loads and the recovery
991 // of the original value.
992 Node* mem_phi = in(Memory);
993 Node* offset = in(Address)->in(AddPNode::Offset);
995 Node* in1 = clone();
996 Node* in1_addr = in1->in(Address)->clone();
997 in1_addr->set_req(AddPNode::Base, base->in(allocation_index));
998 in1_addr->set_req(AddPNode::Address, base->in(allocation_index));
999 in1_addr->set_req(AddPNode::Offset, offset);
1000 in1->set_req(0, base->in(allocation_index));
1001 in1->set_req(Address, in1_addr);
1002 in1->set_req(Memory, mem_phi->in(allocation_index));
1004 Node* in2 = clone();
1005 Node* in2_addr = in2->in(Address)->clone();
1006 in2_addr->set_req(AddPNode::Base, base->in(load_index));
1007 in2_addr->set_req(AddPNode::Address, base->in(load_index));
1008 in2_addr->set_req(AddPNode::Offset, offset);
1009 in2->set_req(0, base->in(load_index));
1010 in2->set_req(Address, in2_addr);
1011 in2->set_req(Memory, mem_phi->in(load_index));
1013 in1_addr = phase->transform(in1_addr);
1014 in1 = phase->transform(in1);
1015 in2_addr = phase->transform(in2_addr);
1016 in2 = phase->transform(in2);
1018 PhiNode* result = PhiNode::make_blank(base->in(0), this);
1019 result->set_req(allocation_index, in1);
1020 result->set_req(load_index, in2);
1021 return result;
1022 }
1023 } else if (base->is_Load()) {
1024 // Eliminate the load of Integer.value for integers from the cache
1025 // array by deriving the value from the index into the array.
1026 // Capture the offset of the load and then reverse the computation.
1027 Node* load_base = base->in(Address)->in(AddPNode::Base);
1028 if (load_base != NULL) {
1029 Compile::AliasType* atp = phase->C->alias_type(load_base->adr_type());
1030 intptr_t cache_offset;
1031 int shift = -1;
1032 Node* cache = NULL;
1033 if (is_autobox_cache(atp)) {
1034 shift = exact_log2(type2aelembytes(T_OBJECT));
1035 cache = AddPNode::Ideal_base_and_offset(load_base->in(Address), phase, cache_offset);
1036 }
1037 if (cache != NULL && base->in(Address)->is_AddP()) {
1038 Node* elements[4];
1039 int count = base->in(Address)->as_AddP()->unpack_offsets(elements, ARRAY_SIZE(elements));
1040 int cache_low;
1041 if (count > 0 && fetch_autobox_base(atp, cache_low)) {
1042 int offset = arrayOopDesc::base_offset_in_bytes(memory_type()) - (cache_low << shift);
1043 // Add up all the offsets making of the address of the load
1044 Node* result = elements[0];
1045 for (int i = 1; i < count; i++) {
1046 result = phase->transform(new (phase->C, 3) AddXNode(result, elements[i]));
1047 }
1048 // Remove the constant offset from the address and then
1049 // remove the scaling of the offset to recover the original index.
1050 result = phase->transform(new (phase->C, 3) AddXNode(result, phase->MakeConX(-offset)));
1051 if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) {
1052 // Peel the shift off directly but wrap it in a dummy node
1053 // since Ideal can't return existing nodes
1054 result = new (phase->C, 3) RShiftXNode(result->in(1), phase->intcon(0));
1055 } else {
1056 result = new (phase->C, 3) RShiftXNode(result, phase->intcon(shift));
1057 }
1058 #ifdef _LP64
1059 result = new (phase->C, 2) ConvL2INode(phase->transform(result));
1060 #endif
1061 return result;
1062 }
1063 }
1064 }
1065 }
1066 return NULL;
1067 }
1070 //------------------------------Ideal------------------------------------------
1071 // If the load is from Field memory and the pointer is non-null, we can
1072 // zero out the control input.
1073 // If the offset is constant and the base is an object allocation,
1074 // try to hook me up to the exact initializing store.
1075 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1076 Node* p = MemNode::Ideal_common(phase, can_reshape);
1077 if (p) return (p == NodeSentinel) ? NULL : p;
1079 Node* ctrl = in(MemNode::Control);
1080 Node* address = in(MemNode::Address);
1082 // Skip up past a SafePoint control. Cannot do this for Stores because
1083 // pointer stores & cardmarks must stay on the same side of a SafePoint.
1084 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint &&
1085 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw ) {
1086 ctrl = ctrl->in(0);
1087 set_req(MemNode::Control,ctrl);
1088 }
1090 // Check for useless control edge in some common special cases
1091 if (in(MemNode::Control) != NULL) {
1092 intptr_t ignore = 0;
1093 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1094 if (base != NULL
1095 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1096 && detect_dominating_control(base->in(0), phase->C->start())) {
1097 // A method-invariant, non-null address (constant or 'this' argument).
1098 set_req(MemNode::Control, NULL);
1099 }
1100 }
1102 if (EliminateAutoBox && can_reshape && in(Address)->is_AddP()) {
1103 Node* base = in(Address)->in(AddPNode::Base);
1104 if (base != NULL) {
1105 Compile::AliasType* atp = phase->C->alias_type(adr_type());
1106 if (is_autobox_object(atp)) {
1107 Node* result = eliminate_autobox(phase);
1108 if (result != NULL) return result;
1109 }
1110 }
1111 }
1113 Node* mem = in(MemNode::Memory);
1114 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1116 if (addr_t != NULL) {
1117 // try to optimize our memory input
1118 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, phase);
1119 if (opt_mem != mem) {
1120 set_req(MemNode::Memory, opt_mem);
1121 return this;
1122 }
1123 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1124 if (can_reshape && opt_mem->is_Phi() &&
1125 (t_oop != NULL) && t_oop->is_instance_field()) {
1126 assert(t_oop->offset() != Type::OffsetBot && t_oop->offset() != Type::OffsetTop, "");
1127 Node *region = opt_mem->in(0);
1128 uint cnt = opt_mem->req();
1129 for( uint i = 1; i < cnt; i++ ) {
1130 Node *in = opt_mem->in(i);
1131 if( in == NULL ) {
1132 region = NULL; // Wait stable graph
1133 break;
1134 }
1135 }
1136 if (region != NULL) {
1137 // Check for loop invariant.
1138 if (cnt == 3) {
1139 for( uint i = 1; i < cnt; i++ ) {
1140 Node *in = opt_mem->in(i);
1141 Node* m = MemNode::optimize_memory_chain(in, addr_t, phase);
1142 if (m == opt_mem) {
1143 set_req(MemNode::Memory, opt_mem->in(cnt - i)); // Skip this phi.
1144 return this;
1145 }
1146 }
1147 }
1148 // Split through Phi (see original code in loopopts.cpp).
1149 assert(phase->C->have_alias_type(addr_t), "instance should have alias type");
1151 // Do nothing here if Identity will find a value
1152 // (to avoid infinite chain of value phis generation).
1153 if ( !phase->eqv(this, this->Identity(phase)) )
1154 return NULL;
1156 const Type* this_type = this->bottom_type();
1157 int this_index = phase->C->get_alias_index(addr_t);
1158 int this_offset = addr_t->offset();
1159 int this_iid = addr_t->is_oopptr()->instance_id();
1160 int wins = 0;
1161 PhaseIterGVN *igvn = phase->is_IterGVN();
1162 Node *phi = new (igvn->C, region->req()) PhiNode(region, this_type, NULL, this_iid, this_index, this_offset);
1163 for( uint i = 1; i < region->req(); i++ ) {
1164 Node *x;
1165 Node* the_clone = NULL;
1166 if( region->in(i) == phase->C->top() ) {
1167 x = phase->C->top(); // Dead path? Use a dead data op
1168 } else {
1169 x = this->clone(); // Else clone up the data op
1170 the_clone = x; // Remember for possible deletion.
1171 // Alter data node to use pre-phi inputs
1172 if( this->in(0) == region ) {
1173 x->set_req( 0, region->in(i) );
1174 } else {
1175 x->set_req( 0, NULL );
1176 }
1177 for( uint j = 1; j < this->req(); j++ ) {
1178 Node *in = this->in(j);
1179 if( in->is_Phi() && in->in(0) == region )
1180 x->set_req( j, in->in(i) ); // Use pre-Phi input for the clone
1181 }
1182 }
1183 // Check for a 'win' on some paths
1184 const Type *t = x->Value(igvn);
1186 bool singleton = t->singleton();
1188 // See comments in PhaseIdealLoop::split_thru_phi().
1189 if( singleton && t == Type::TOP ) {
1190 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1191 }
1193 if( singleton ) {
1194 wins++;
1195 x = igvn->makecon(t);
1196 } else {
1197 // We now call Identity to try to simplify the cloned node.
1198 // Note that some Identity methods call phase->type(this).
1199 // Make sure that the type array is big enough for
1200 // our new node, even though we may throw the node away.
1201 // (This tweaking with igvn only works because x is a new node.)
1202 igvn->set_type(x, t);
1203 Node *y = x->Identity(igvn);
1204 if( y != x ) {
1205 wins++;
1206 x = y;
1207 } else {
1208 y = igvn->hash_find(x);
1209 if( y ) {
1210 wins++;
1211 x = y;
1212 } else {
1213 // Else x is a new node we are keeping
1214 // We do not need register_new_node_with_optimizer
1215 // because set_type has already been called.
1216 igvn->_worklist.push(x);
1217 }
1218 }
1219 }
1220 if (x != the_clone && the_clone != NULL)
1221 igvn->remove_dead_node(the_clone);
1222 phi->set_req(i, x);
1223 }
1224 if( wins > 0 ) {
1225 // Record Phi
1226 igvn->register_new_node_with_optimizer(phi);
1227 return phi;
1228 } else {
1229 igvn->remove_dead_node(phi);
1230 }
1231 }
1232 }
1233 }
1235 // Check for prior store with a different base or offset; make Load
1236 // independent. Skip through any number of them. Bail out if the stores
1237 // are in an endless dead cycle and report no progress. This is a key
1238 // transform for Reflection. However, if after skipping through the Stores
1239 // we can't then fold up against a prior store do NOT do the transform as
1240 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
1241 // array memory alive twice: once for the hoisted Load and again after the
1242 // bypassed Store. This situation only works if EVERYBODY who does
1243 // anti-dependence work knows how to bypass. I.e. we need all
1244 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
1245 // the alias index stuff. So instead, peek through Stores and IFF we can
1246 // fold up, do so.
1247 Node* prev_mem = find_previous_store(phase);
1248 // Steps (a), (b): Walk past independent stores to find an exact match.
1249 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) {
1250 // (c) See if we can fold up on the spot, but don't fold up here.
1251 // Fold-up might require truncation (for LoadB/LoadS/LoadC) or
1252 // just return a prior value, which is done by Identity calls.
1253 if (can_see_stored_value(prev_mem, phase)) {
1254 // Make ready for step (d):
1255 set_req(MemNode::Memory, prev_mem);
1256 return this;
1257 }
1258 }
1260 return NULL; // No further progress
1261 }
1263 // Helper to recognize certain Klass fields which are invariant across
1264 // some group of array types (e.g., int[] or all T[] where T < Object).
1265 const Type*
1266 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1267 ciKlass* klass) const {
1268 if (tkls->offset() == Klass::modifier_flags_offset_in_bytes() + (int)sizeof(oopDesc)) {
1269 // The field is Klass::_modifier_flags. Return its (constant) value.
1270 // (Folds up the 2nd indirection in aClassConstant.getModifiers().)
1271 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags");
1272 return TypeInt::make(klass->modifier_flags());
1273 }
1274 if (tkls->offset() == Klass::access_flags_offset_in_bytes() + (int)sizeof(oopDesc)) {
1275 // The field is Klass::_access_flags. Return its (constant) value.
1276 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1277 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags");
1278 return TypeInt::make(klass->access_flags());
1279 }
1280 if (tkls->offset() == Klass::layout_helper_offset_in_bytes() + (int)sizeof(oopDesc)) {
1281 // The field is Klass::_layout_helper. Return its constant value if known.
1282 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper");
1283 return TypeInt::make(klass->layout_helper());
1284 }
1286 // No match.
1287 return NULL;
1288 }
1290 //------------------------------Value-----------------------------------------
1291 const Type *LoadNode::Value( PhaseTransform *phase ) const {
1292 // Either input is TOP ==> the result is TOP
1293 Node* mem = in(MemNode::Memory);
1294 const Type *t1 = phase->type(mem);
1295 if (t1 == Type::TOP) return Type::TOP;
1296 Node* adr = in(MemNode::Address);
1297 const TypePtr* tp = phase->type(adr)->isa_ptr();
1298 if (tp == NULL || tp->empty()) return Type::TOP;
1299 int off = tp->offset();
1300 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
1302 // Try to guess loaded type from pointer type
1303 if (tp->base() == Type::AryPtr) {
1304 const Type *t = tp->is_aryptr()->elem();
1305 // Don't do this for integer types. There is only potential profit if
1306 // the element type t is lower than _type; that is, for int types, if _type is
1307 // more restrictive than t. This only happens here if one is short and the other
1308 // char (both 16 bits), and in those cases we've made an intentional decision
1309 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
1310 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
1311 //
1312 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
1313 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
1314 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
1315 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
1316 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
1317 // In fact, that could have been the original type of p1, and p1 could have
1318 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
1319 // expression (LShiftL quux 3) independently optimized to the constant 8.
1320 if ((t->isa_int() == NULL) && (t->isa_long() == NULL)
1321 && Opcode() != Op_LoadKlass) {
1322 // t might actually be lower than _type, if _type is a unique
1323 // concrete subclass of abstract class t.
1324 // Make sure the reference is not into the header, by comparing
1325 // the offset against the offset of the start of the array's data.
1326 // Different array types begin at slightly different offsets (12 vs. 16).
1327 // We choose T_BYTE as an example base type that is least restrictive
1328 // as to alignment, which will therefore produce the smallest
1329 // possible base offset.
1330 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
1331 if ((uint)off >= (uint)min_base_off) { // is the offset beyond the header?
1332 const Type* jt = t->join(_type);
1333 // In any case, do not allow the join, per se, to empty out the type.
1334 if (jt->empty() && !t->empty()) {
1335 // This can happen if a interface-typed array narrows to a class type.
1336 jt = _type;
1337 }
1339 if (EliminateAutoBox) {
1340 // The pointers in the autobox arrays are always non-null
1341 Node* base = in(Address)->in(AddPNode::Base);
1342 if (base != NULL) {
1343 Compile::AliasType* atp = phase->C->alias_type(base->adr_type());
1344 if (is_autobox_cache(atp)) {
1345 return jt->join(TypePtr::NOTNULL)->is_ptr();
1346 }
1347 }
1348 }
1349 return jt;
1350 }
1351 }
1352 } else if (tp->base() == Type::InstPtr) {
1353 assert( off != Type::OffsetBot ||
1354 // arrays can be cast to Objects
1355 tp->is_oopptr()->klass()->is_java_lang_Object() ||
1356 // unsafe field access may not have a constant offset
1357 phase->C->has_unsafe_access(),
1358 "Field accesses must be precise" );
1359 // For oop loads, we expect the _type to be precise
1360 } else if (tp->base() == Type::KlassPtr) {
1361 assert( off != Type::OffsetBot ||
1362 // arrays can be cast to Objects
1363 tp->is_klassptr()->klass()->is_java_lang_Object() ||
1364 // also allow array-loading from the primary supertype
1365 // array during subtype checks
1366 Opcode() == Op_LoadKlass,
1367 "Field accesses must be precise" );
1368 // For klass/static loads, we expect the _type to be precise
1369 }
1371 const TypeKlassPtr *tkls = tp->isa_klassptr();
1372 if (tkls != NULL && !StressReflectiveCode) {
1373 ciKlass* klass = tkls->klass();
1374 if (klass->is_loaded() && tkls->klass_is_exact()) {
1375 // We are loading a field from a Klass metaobject whose identity
1376 // is known at compile time (the type is "exact" or "precise").
1377 // Check for fields we know are maintained as constants by the VM.
1378 if (tkls->offset() == Klass::super_check_offset_offset_in_bytes() + (int)sizeof(oopDesc)) {
1379 // The field is Klass::_super_check_offset. Return its (constant) value.
1380 // (Folds up type checking code.)
1381 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
1382 return TypeInt::make(klass->super_check_offset());
1383 }
1384 // Compute index into primary_supers array
1385 juint depth = (tkls->offset() - (Klass::primary_supers_offset_in_bytes() + (int)sizeof(oopDesc))) / sizeof(klassOop);
1386 // Check for overflowing; use unsigned compare to handle the negative case.
1387 if( depth < ciKlass::primary_super_limit() ) {
1388 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1389 // (Folds up type checking code.)
1390 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1391 ciKlass *ss = klass->super_of_depth(depth);
1392 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1393 }
1394 const Type* aift = load_array_final_field(tkls, klass);
1395 if (aift != NULL) return aift;
1396 if (tkls->offset() == in_bytes(arrayKlass::component_mirror_offset()) + (int)sizeof(oopDesc)
1397 && klass->is_array_klass()) {
1398 // The field is arrayKlass::_component_mirror. Return its (constant) value.
1399 // (Folds up aClassConstant.getComponentType, common in Arrays.copyOf.)
1400 assert(Opcode() == Op_LoadP, "must load an oop from _component_mirror");
1401 return TypeInstPtr::make(klass->as_array_klass()->component_mirror());
1402 }
1403 if (tkls->offset() == Klass::java_mirror_offset_in_bytes() + (int)sizeof(oopDesc)) {
1404 // The field is Klass::_java_mirror. Return its (constant) value.
1405 // (Folds up the 2nd indirection in anObjConstant.getClass().)
1406 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
1407 return TypeInstPtr::make(klass->java_mirror());
1408 }
1409 }
1411 // We can still check if we are loading from the primary_supers array at a
1412 // shallow enough depth. Even though the klass is not exact, entries less
1413 // than or equal to its super depth are correct.
1414 if (klass->is_loaded() ) {
1415 ciType *inner = klass->klass();
1416 while( inner->is_obj_array_klass() )
1417 inner = inner->as_obj_array_klass()->base_element_type();
1418 if( inner->is_instance_klass() &&
1419 !inner->as_instance_klass()->flags().is_interface() ) {
1420 // Compute index into primary_supers array
1421 juint depth = (tkls->offset() - (Klass::primary_supers_offset_in_bytes() + (int)sizeof(oopDesc))) / sizeof(klassOop);
1422 // Check for overflowing; use unsigned compare to handle the negative case.
1423 if( depth < ciKlass::primary_super_limit() &&
1424 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case
1425 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1426 // (Folds up type checking code.)
1427 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1428 ciKlass *ss = klass->super_of_depth(depth);
1429 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1430 }
1431 }
1432 }
1434 // If the type is enough to determine that the thing is not an array,
1435 // we can give the layout_helper a positive interval type.
1436 // This will help short-circuit some reflective code.
1437 if (tkls->offset() == Klass::layout_helper_offset_in_bytes() + (int)sizeof(oopDesc)
1438 && !klass->is_array_klass() // not directly typed as an array
1439 && !klass->is_interface() // specifically not Serializable & Cloneable
1440 && !klass->is_java_lang_Object() // not the supertype of all T[]
1441 ) {
1442 // Note: When interfaces are reliable, we can narrow the interface
1443 // test to (klass != Serializable && klass != Cloneable).
1444 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
1445 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
1446 // The key property of this type is that it folds up tests
1447 // for array-ness, since it proves that the layout_helper is positive.
1448 // Thus, a generic value like the basic object layout helper works fine.
1449 return TypeInt::make(min_size, max_jint, Type::WidenMin);
1450 }
1451 }
1453 // If we are loading from a freshly-allocated object, produce a zero,
1454 // if the load is provably beyond the header of the object.
1455 // (Also allow a variable load from a fresh array to produce zero.)
1456 if (ReduceFieldZeroing) {
1457 Node* value = can_see_stored_value(mem,phase);
1458 if (value != NULL && value->is_Con())
1459 return value->bottom_type();
1460 }
1462 const TypeOopPtr *tinst = tp->isa_oopptr();
1463 if (tinst != NULL && tinst->is_instance_field()) {
1464 // If we have an instance type and our memory input is the
1465 // programs's initial memory state, there is no matching store,
1466 // so just return a zero of the appropriate type
1467 Node *mem = in(MemNode::Memory);
1468 if (mem->is_Parm() && mem->in(0)->is_Start()) {
1469 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
1470 return Type::get_zero_type(_type->basic_type());
1471 }
1472 }
1473 return _type;
1474 }
1476 //------------------------------match_edge-------------------------------------
1477 // Do we Match on this edge index or not? Match only the address.
1478 uint LoadNode::match_edge(uint idx) const {
1479 return idx == MemNode::Address;
1480 }
1482 //--------------------------LoadBNode::Ideal--------------------------------------
1483 //
1484 // If the previous store is to the same address as this load,
1485 // and the value stored was larger than a byte, replace this load
1486 // with the value stored truncated to a byte. If no truncation is
1487 // needed, the replacement is done in LoadNode::Identity().
1488 //
1489 Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1490 Node* mem = in(MemNode::Memory);
1491 Node* value = can_see_stored_value(mem,phase);
1492 if( value && !phase->type(value)->higher_equal( _type ) ) {
1493 Node *result = phase->transform( new (phase->C, 3) LShiftINode(value, phase->intcon(24)) );
1494 return new (phase->C, 3) RShiftINode(result, phase->intcon(24));
1495 }
1496 // Identity call will handle the case where truncation is not needed.
1497 return LoadNode::Ideal(phase, can_reshape);
1498 }
1500 //--------------------------LoadCNode::Ideal--------------------------------------
1501 //
1502 // If the previous store is to the same address as this load,
1503 // and the value stored was larger than a char, replace this load
1504 // with the value stored truncated to a char. If no truncation is
1505 // needed, the replacement is done in LoadNode::Identity().
1506 //
1507 Node *LoadCNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1508 Node* mem = in(MemNode::Memory);
1509 Node* value = can_see_stored_value(mem,phase);
1510 if( value && !phase->type(value)->higher_equal( _type ) )
1511 return new (phase->C, 3) AndINode(value,phase->intcon(0xFFFF));
1512 // Identity call will handle the case where truncation is not needed.
1513 return LoadNode::Ideal(phase, can_reshape);
1514 }
1516 //--------------------------LoadSNode::Ideal--------------------------------------
1517 //
1518 // If the previous store is to the same address as this load,
1519 // and the value stored was larger than a short, replace this load
1520 // with the value stored truncated to a short. If no truncation is
1521 // needed, the replacement is done in LoadNode::Identity().
1522 //
1523 Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1524 Node* mem = in(MemNode::Memory);
1525 Node* value = can_see_stored_value(mem,phase);
1526 if( value && !phase->type(value)->higher_equal( _type ) ) {
1527 Node *result = phase->transform( new (phase->C, 3) LShiftINode(value, phase->intcon(16)) );
1528 return new (phase->C, 3) RShiftINode(result, phase->intcon(16));
1529 }
1530 // Identity call will handle the case where truncation is not needed.
1531 return LoadNode::Ideal(phase, can_reshape);
1532 }
1534 //=============================================================================
1535 //------------------------------Value------------------------------------------
1536 const Type *LoadKlassNode::Value( PhaseTransform *phase ) const {
1537 // Either input is TOP ==> the result is TOP
1538 const Type *t1 = phase->type( in(MemNode::Memory) );
1539 if (t1 == Type::TOP) return Type::TOP;
1540 Node *adr = in(MemNode::Address);
1541 const Type *t2 = phase->type( adr );
1542 if (t2 == Type::TOP) return Type::TOP;
1543 const TypePtr *tp = t2->is_ptr();
1544 if (TypePtr::above_centerline(tp->ptr()) ||
1545 tp->ptr() == TypePtr::Null) return Type::TOP;
1547 // Return a more precise klass, if possible
1548 const TypeInstPtr *tinst = tp->isa_instptr();
1549 if (tinst != NULL) {
1550 ciInstanceKlass* ik = tinst->klass()->as_instance_klass();
1551 int offset = tinst->offset();
1552 if (ik == phase->C->env()->Class_klass()
1553 && (offset == java_lang_Class::klass_offset_in_bytes() ||
1554 offset == java_lang_Class::array_klass_offset_in_bytes())) {
1555 // We are loading a special hidden field from a Class mirror object,
1556 // the field which points to the VM's Klass metaobject.
1557 ciType* t = tinst->java_mirror_type();
1558 // java_mirror_type returns non-null for compile-time Class constants.
1559 if (t != NULL) {
1560 // constant oop => constant klass
1561 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
1562 return TypeKlassPtr::make(ciArrayKlass::make(t));
1563 }
1564 if (!t->is_klass()) {
1565 // a primitive Class (e.g., int.class) has NULL for a klass field
1566 return TypePtr::NULL_PTR;
1567 }
1568 // (Folds up the 1st indirection in aClassConstant.getModifiers().)
1569 return TypeKlassPtr::make(t->as_klass());
1570 }
1571 // non-constant mirror, so we can't tell what's going on
1572 }
1573 if( !ik->is_loaded() )
1574 return _type; // Bail out if not loaded
1575 if (offset == oopDesc::klass_offset_in_bytes()) {
1576 if (tinst->klass_is_exact()) {
1577 return TypeKlassPtr::make(ik);
1578 }
1579 // See if we can become precise: no subklasses and no interface
1580 // (Note: We need to support verified interfaces.)
1581 if (!ik->is_interface() && !ik->has_subklass()) {
1582 //assert(!UseExactTypes, "this code should be useless with exact types");
1583 // Add a dependence; if any subclass added we need to recompile
1584 if (!ik->is_final()) {
1585 // %%% should use stronger assert_unique_concrete_subtype instead
1586 phase->C->dependencies()->assert_leaf_type(ik);
1587 }
1588 // Return precise klass
1589 return TypeKlassPtr::make(ik);
1590 }
1592 // Return root of possible klass
1593 return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/);
1594 }
1595 }
1597 // Check for loading klass from an array
1598 const TypeAryPtr *tary = tp->isa_aryptr();
1599 if( tary != NULL ) {
1600 ciKlass *tary_klass = tary->klass();
1601 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP
1602 && tary->offset() == oopDesc::klass_offset_in_bytes()) {
1603 if (tary->klass_is_exact()) {
1604 return TypeKlassPtr::make(tary_klass);
1605 }
1606 ciArrayKlass *ak = tary->klass()->as_array_klass();
1607 // If the klass is an object array, we defer the question to the
1608 // array component klass.
1609 if( ak->is_obj_array_klass() ) {
1610 assert( ak->is_loaded(), "" );
1611 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass();
1612 if( base_k->is_loaded() && base_k->is_instance_klass() ) {
1613 ciInstanceKlass* ik = base_k->as_instance_klass();
1614 // See if we can become precise: no subklasses and no interface
1615 if (!ik->is_interface() && !ik->has_subklass()) {
1616 //assert(!UseExactTypes, "this code should be useless with exact types");
1617 // Add a dependence; if any subclass added we need to recompile
1618 if (!ik->is_final()) {
1619 phase->C->dependencies()->assert_leaf_type(ik);
1620 }
1621 // Return precise array klass
1622 return TypeKlassPtr::make(ak);
1623 }
1624 }
1625 return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/);
1626 } else { // Found a type-array?
1627 //assert(!UseExactTypes, "this code should be useless with exact types");
1628 assert( ak->is_type_array_klass(), "" );
1629 return TypeKlassPtr::make(ak); // These are always precise
1630 }
1631 }
1632 }
1634 // Check for loading klass from an array klass
1635 const TypeKlassPtr *tkls = tp->isa_klassptr();
1636 if (tkls != NULL && !StressReflectiveCode) {
1637 ciKlass* klass = tkls->klass();
1638 if( !klass->is_loaded() )
1639 return _type; // Bail out if not loaded
1640 if( klass->is_obj_array_klass() &&
1641 (uint)tkls->offset() == objArrayKlass::element_klass_offset_in_bytes() + sizeof(oopDesc)) {
1642 ciKlass* elem = klass->as_obj_array_klass()->element_klass();
1643 // // Always returning precise element type is incorrect,
1644 // // e.g., element type could be object and array may contain strings
1645 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
1647 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
1648 // according to the element type's subclassing.
1649 return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/);
1650 }
1651 if( klass->is_instance_klass() && tkls->klass_is_exact() &&
1652 (uint)tkls->offset() == Klass::super_offset_in_bytes() + sizeof(oopDesc)) {
1653 ciKlass* sup = klass->as_instance_klass()->super();
1654 // The field is Klass::_super. Return its (constant) value.
1655 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
1656 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR;
1657 }
1658 }
1660 // Bailout case
1661 return LoadNode::Value(phase);
1662 }
1664 //------------------------------Identity---------------------------------------
1665 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
1666 // Also feed through the klass in Allocate(...klass...)._klass.
1667 Node* LoadKlassNode::Identity( PhaseTransform *phase ) {
1668 Node* x = LoadNode::Identity(phase);
1669 if (x != this) return x;
1671 // Take apart the address into an oop and and offset.
1672 // Return 'this' if we cannot.
1673 Node* adr = in(MemNode::Address);
1674 intptr_t offset = 0;
1675 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
1676 if (base == NULL) return this;
1677 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
1678 if (toop == NULL) return this;
1680 // We can fetch the klass directly through an AllocateNode.
1681 // This works even if the klass is not constant (clone or newArray).
1682 if (offset == oopDesc::klass_offset_in_bytes()) {
1683 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
1684 if (allocated_klass != NULL) {
1685 return allocated_klass;
1686 }
1687 }
1689 // Simplify k.java_mirror.as_klass to plain k, where k is a klassOop.
1690 // Simplify ak.component_mirror.array_klass to plain ak, ak an arrayKlass.
1691 // See inline_native_Class_query for occurrences of these patterns.
1692 // Java Example: x.getClass().isAssignableFrom(y)
1693 // Java Example: Array.newInstance(x.getClass().getComponentType(), n)
1694 //
1695 // This improves reflective code, often making the Class
1696 // mirror go completely dead. (Current exception: Class
1697 // mirrors may appear in debug info, but we could clean them out by
1698 // introducing a new debug info operator for klassOop.java_mirror).
1699 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass()
1700 && (offset == java_lang_Class::klass_offset_in_bytes() ||
1701 offset == java_lang_Class::array_klass_offset_in_bytes())) {
1702 // We are loading a special hidden field from a Class mirror,
1703 // the field which points to its Klass or arrayKlass metaobject.
1704 if (base->is_Load()) {
1705 Node* adr2 = base->in(MemNode::Address);
1706 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
1707 if (tkls != NULL && !tkls->empty()
1708 && (tkls->klass()->is_instance_klass() ||
1709 tkls->klass()->is_array_klass())
1710 && adr2->is_AddP()
1711 ) {
1712 int mirror_field = Klass::java_mirror_offset_in_bytes();
1713 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
1714 mirror_field = in_bytes(arrayKlass::component_mirror_offset());
1715 }
1716 if (tkls->offset() == mirror_field + (int)sizeof(oopDesc)) {
1717 return adr2->in(AddPNode::Base);
1718 }
1719 }
1720 }
1721 }
1723 return this;
1724 }
1726 //------------------------------Value-----------------------------------------
1727 const Type *LoadRangeNode::Value( PhaseTransform *phase ) const {
1728 // Either input is TOP ==> the result is TOP
1729 const Type *t1 = phase->type( in(MemNode::Memory) );
1730 if( t1 == Type::TOP ) return Type::TOP;
1731 Node *adr = in(MemNode::Address);
1732 const Type *t2 = phase->type( adr );
1733 if( t2 == Type::TOP ) return Type::TOP;
1734 const TypePtr *tp = t2->is_ptr();
1735 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
1736 const TypeAryPtr *tap = tp->isa_aryptr();
1737 if( !tap ) return _type;
1738 return tap->size();
1739 }
1741 //------------------------------Identity---------------------------------------
1742 // Feed through the length in AllocateArray(...length...)._length.
1743 Node* LoadRangeNode::Identity( PhaseTransform *phase ) {
1744 Node* x = LoadINode::Identity(phase);
1745 if (x != this) return x;
1747 // Take apart the address into an oop and and offset.
1748 // Return 'this' if we cannot.
1749 Node* adr = in(MemNode::Address);
1750 intptr_t offset = 0;
1751 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
1752 if (base == NULL) return this;
1753 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
1754 if (tary == NULL) return this;
1756 // We can fetch the length directly through an AllocateArrayNode.
1757 // This works even if the length is not constant (clone or newArray).
1758 if (offset == arrayOopDesc::length_offset_in_bytes()) {
1759 Node* allocated_length = AllocateArrayNode::Ideal_length(base, phase);
1760 if (allocated_length != NULL) {
1761 return allocated_length;
1762 }
1763 }
1765 return this;
1767 }
1768 //=============================================================================
1769 //---------------------------StoreNode::make-----------------------------------
1770 // Polymorphic factory method:
1771 StoreNode* StoreNode::make( PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt ) {
1772 Compile* C = gvn.C;
1774 switch (bt) {
1775 case T_BOOLEAN:
1776 case T_BYTE: return new (C, 4) StoreBNode(ctl, mem, adr, adr_type, val);
1777 case T_INT: return new (C, 4) StoreINode(ctl, mem, adr, adr_type, val);
1778 case T_CHAR:
1779 case T_SHORT: return new (C, 4) StoreCNode(ctl, mem, adr, adr_type, val);
1780 case T_LONG: return new (C, 4) StoreLNode(ctl, mem, adr, adr_type, val);
1781 case T_FLOAT: return new (C, 4) StoreFNode(ctl, mem, adr, adr_type, val);
1782 case T_DOUBLE: return new (C, 4) StoreDNode(ctl, mem, adr, adr_type, val);
1783 case T_ADDRESS:
1784 case T_OBJECT:
1785 #ifdef _LP64
1786 if (adr->bottom_type()->is_narrow() ||
1787 (UseCompressedOops && val->bottom_type()->isa_klassptr() &&
1788 adr->bottom_type()->isa_rawptr())) {
1789 const TypePtr* type = val->bottom_type()->is_ptr();
1790 Node* cp;
1791 if (type->isa_oopptr()) {
1792 const TypeNarrowOop* etype = type->is_oopptr()->make_narrowoop();
1793 cp = gvn.transform(new (C, 2) EncodePNode(val, etype));
1794 } else if (type == TypePtr::NULL_PTR) {
1795 cp = gvn.transform(new (C, 1) ConNNode(TypeNarrowOop::NULL_PTR));
1796 } else {
1797 ShouldNotReachHere();
1798 }
1799 return new (C, 4) StoreNNode(ctl, mem, adr, adr_type, cp);
1800 } else
1801 #endif
1802 {
1803 return new (C, 4) StorePNode(ctl, mem, adr, adr_type, val);
1804 }
1805 }
1806 ShouldNotReachHere();
1807 return (StoreNode*)NULL;
1808 }
1810 StoreLNode* StoreLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val) {
1811 bool require_atomic = true;
1812 return new (C, 4) StoreLNode(ctl, mem, adr, adr_type, val, require_atomic);
1813 }
1816 //--------------------------bottom_type----------------------------------------
1817 const Type *StoreNode::bottom_type() const {
1818 return Type::MEMORY;
1819 }
1821 //------------------------------hash-------------------------------------------
1822 uint StoreNode::hash() const {
1823 // unroll addition of interesting fields
1824 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
1826 // Since they are not commoned, do not hash them:
1827 return NO_HASH;
1828 }
1830 //------------------------------Ideal------------------------------------------
1831 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
1832 // When a store immediately follows a relevant allocation/initialization,
1833 // try to capture it into the initialization, or hoist it above.
1834 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1835 Node* p = MemNode::Ideal_common(phase, can_reshape);
1836 if (p) return (p == NodeSentinel) ? NULL : p;
1838 Node* mem = in(MemNode::Memory);
1839 Node* address = in(MemNode::Address);
1841 // Back-to-back stores to same address? Fold em up.
1842 // Generally unsafe if I have intervening uses...
1843 if (mem->is_Store() && phase->eqv_uncast(mem->in(MemNode::Address), address)) {
1844 // Looking at a dead closed cycle of memory?
1845 assert(mem != mem->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
1847 assert(Opcode() == mem->Opcode() ||
1848 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw,
1849 "no mismatched stores, except on raw memory");
1851 if (mem->outcnt() == 1 && // check for intervening uses
1852 mem->as_Store()->memory_size() <= this->memory_size()) {
1853 // If anybody other than 'this' uses 'mem', we cannot fold 'mem' away.
1854 // For example, 'mem' might be the final state at a conditional return.
1855 // Or, 'mem' might be used by some node which is live at the same time
1856 // 'this' is live, which might be unschedulable. So, require exactly
1857 // ONE user, the 'this' store, until such time as we clone 'mem' for
1858 // each of 'mem's uses (thus making the exactly-1-user-rule hold true).
1859 if (can_reshape) { // (%%% is this an anachronism?)
1860 set_req_X(MemNode::Memory, mem->in(MemNode::Memory),
1861 phase->is_IterGVN());
1862 } else {
1863 // It's OK to do this in the parser, since DU info is always accurate,
1864 // and the parser always refers to nodes via SafePointNode maps.
1865 set_req(MemNode::Memory, mem->in(MemNode::Memory));
1866 }
1867 return this;
1868 }
1869 }
1871 // Capture an unaliased, unconditional, simple store into an initializer.
1872 // Or, if it is independent of the allocation, hoist it above the allocation.
1873 if (ReduceFieldZeroing && /*can_reshape &&*/
1874 mem->is_Proj() && mem->in(0)->is_Initialize()) {
1875 InitializeNode* init = mem->in(0)->as_Initialize();
1876 intptr_t offset = init->can_capture_store(this, phase);
1877 if (offset > 0) {
1878 Node* moved = init->capture_store(this, offset, phase);
1879 // If the InitializeNode captured me, it made a raw copy of me,
1880 // and I need to disappear.
1881 if (moved != NULL) {
1882 // %%% hack to ensure that Ideal returns a new node:
1883 mem = MergeMemNode::make(phase->C, mem);
1884 return mem; // fold me away
1885 }
1886 }
1887 }
1889 return NULL; // No further progress
1890 }
1892 //------------------------------Value-----------------------------------------
1893 const Type *StoreNode::Value( PhaseTransform *phase ) const {
1894 // Either input is TOP ==> the result is TOP
1895 const Type *t1 = phase->type( in(MemNode::Memory) );
1896 if( t1 == Type::TOP ) return Type::TOP;
1897 const Type *t2 = phase->type( in(MemNode::Address) );
1898 if( t2 == Type::TOP ) return Type::TOP;
1899 const Type *t3 = phase->type( in(MemNode::ValueIn) );
1900 if( t3 == Type::TOP ) return Type::TOP;
1901 return Type::MEMORY;
1902 }
1904 //------------------------------Identity---------------------------------------
1905 // Remove redundant stores:
1906 // Store(m, p, Load(m, p)) changes to m.
1907 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
1908 Node *StoreNode::Identity( PhaseTransform *phase ) {
1909 Node* mem = in(MemNode::Memory);
1910 Node* adr = in(MemNode::Address);
1911 Node* val = in(MemNode::ValueIn);
1913 // Load then Store? Then the Store is useless
1914 if (val->is_Load() &&
1915 phase->eqv_uncast( val->in(MemNode::Address), adr ) &&
1916 phase->eqv_uncast( val->in(MemNode::Memory ), mem ) &&
1917 val->as_Load()->store_Opcode() == Opcode()) {
1918 return mem;
1919 }
1921 // Two stores in a row of the same value?
1922 if (mem->is_Store() &&
1923 phase->eqv_uncast( mem->in(MemNode::Address), adr ) &&
1924 phase->eqv_uncast( mem->in(MemNode::ValueIn), val ) &&
1925 mem->Opcode() == Opcode()) {
1926 return mem;
1927 }
1929 // Store of zero anywhere into a freshly-allocated object?
1930 // Then the store is useless.
1931 // (It must already have been captured by the InitializeNode.)
1932 if (ReduceFieldZeroing && phase->type(val)->is_zero_type()) {
1933 // a newly allocated object is already all-zeroes everywhere
1934 if (mem->is_Proj() && mem->in(0)->is_Allocate()) {
1935 return mem;
1936 }
1938 // the store may also apply to zero-bits in an earlier object
1939 Node* prev_mem = find_previous_store(phase);
1940 // Steps (a), (b): Walk past independent stores to find an exact match.
1941 if (prev_mem != NULL) {
1942 Node* prev_val = can_see_stored_value(prev_mem, phase);
1943 if (prev_val != NULL && phase->eqv(prev_val, val)) {
1944 // prev_val and val might differ by a cast; it would be good
1945 // to keep the more informative of the two.
1946 return mem;
1947 }
1948 }
1949 }
1951 return this;
1952 }
1954 //------------------------------match_edge-------------------------------------
1955 // Do we Match on this edge index or not? Match only memory & value
1956 uint StoreNode::match_edge(uint idx) const {
1957 return idx == MemNode::Address || idx == MemNode::ValueIn;
1958 }
1960 //------------------------------cmp--------------------------------------------
1961 // Do not common stores up together. They generally have to be split
1962 // back up anyways, so do not bother.
1963 uint StoreNode::cmp( const Node &n ) const {
1964 return (&n == this); // Always fail except on self
1965 }
1967 //------------------------------Ideal_masked_input-----------------------------
1968 // Check for a useless mask before a partial-word store
1969 // (StoreB ... (AndI valIn conIa) )
1970 // If (conIa & mask == mask) this simplifies to
1971 // (StoreB ... (valIn) )
1972 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
1973 Node *val = in(MemNode::ValueIn);
1974 if( val->Opcode() == Op_AndI ) {
1975 const TypeInt *t = phase->type( val->in(2) )->isa_int();
1976 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
1977 set_req(MemNode::ValueIn, val->in(1));
1978 return this;
1979 }
1980 }
1981 return NULL;
1982 }
1985 //------------------------------Ideal_sign_extended_input----------------------
1986 // Check for useless sign-extension before a partial-word store
1987 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) )
1988 // If (conIL == conIR && conIR <= num_bits) this simplifies to
1989 // (StoreB ... (valIn) )
1990 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) {
1991 Node *val = in(MemNode::ValueIn);
1992 if( val->Opcode() == Op_RShiftI ) {
1993 const TypeInt *t = phase->type( val->in(2) )->isa_int();
1994 if( t && t->is_con() && (t->get_con() <= num_bits) ) {
1995 Node *shl = val->in(1);
1996 if( shl->Opcode() == Op_LShiftI ) {
1997 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int();
1998 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) {
1999 set_req(MemNode::ValueIn, shl->in(1));
2000 return this;
2001 }
2002 }
2003 }
2004 }
2005 return NULL;
2006 }
2008 //------------------------------value_never_loaded-----------------------------------
2009 // Determine whether there are any possible loads of the value stored.
2010 // For simplicity, we actually check if there are any loads from the
2011 // address stored to, not just for loads of the value stored by this node.
2012 //
2013 bool StoreNode::value_never_loaded( PhaseTransform *phase) const {
2014 Node *adr = in(Address);
2015 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
2016 if (adr_oop == NULL)
2017 return false;
2018 if (!adr_oop->is_instance_field())
2019 return false; // if not a distinct instance, there may be aliases of the address
2020 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
2021 Node *use = adr->fast_out(i);
2022 int opc = use->Opcode();
2023 if (use->is_Load() || use->is_LoadStore()) {
2024 return false;
2025 }
2026 }
2027 return true;
2028 }
2030 //=============================================================================
2031 //------------------------------Ideal------------------------------------------
2032 // If the store is from an AND mask that leaves the low bits untouched, then
2033 // we can skip the AND operation. If the store is from a sign-extension
2034 // (a left shift, then right shift) we can skip both.
2035 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
2036 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
2037 if( progress != NULL ) return progress;
2039 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
2040 if( progress != NULL ) return progress;
2042 // Finally check the default case
2043 return StoreNode::Ideal(phase, can_reshape);
2044 }
2046 //=============================================================================
2047 //------------------------------Ideal------------------------------------------
2048 // If the store is from an AND mask that leaves the low bits untouched, then
2049 // we can skip the AND operation
2050 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
2051 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
2052 if( progress != NULL ) return progress;
2054 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
2055 if( progress != NULL ) return progress;
2057 // Finally check the default case
2058 return StoreNode::Ideal(phase, can_reshape);
2059 }
2061 //=============================================================================
2062 //------------------------------Identity---------------------------------------
2063 Node *StoreCMNode::Identity( PhaseTransform *phase ) {
2064 // No need to card mark when storing a null ptr
2065 Node* my_store = in(MemNode::OopStore);
2066 if (my_store->is_Store()) {
2067 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) );
2068 if( t1 == TypePtr::NULL_PTR ) {
2069 return in(MemNode::Memory);
2070 }
2071 }
2072 return this;
2073 }
2075 //------------------------------Value-----------------------------------------
2076 const Type *StoreCMNode::Value( PhaseTransform *phase ) const {
2077 // Either input is TOP ==> the result is TOP
2078 const Type *t = phase->type( in(MemNode::Memory) );
2079 if( t == Type::TOP ) return Type::TOP;
2080 t = phase->type( in(MemNode::Address) );
2081 if( t == Type::TOP ) return Type::TOP;
2082 t = phase->type( in(MemNode::ValueIn) );
2083 if( t == Type::TOP ) return Type::TOP;
2084 // If extra input is TOP ==> the result is TOP
2085 t = phase->type( in(MemNode::OopStore) );
2086 if( t == Type::TOP ) return Type::TOP;
2088 return StoreNode::Value( phase );
2089 }
2092 //=============================================================================
2093 //----------------------------------SCMemProjNode------------------------------
2094 const Type * SCMemProjNode::Value( PhaseTransform *phase ) const
2095 {
2096 return bottom_type();
2097 }
2099 //=============================================================================
2100 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : Node(5) {
2101 init_req(MemNode::Control, c );
2102 init_req(MemNode::Memory , mem);
2103 init_req(MemNode::Address, adr);
2104 init_req(MemNode::ValueIn, val);
2105 init_req( ExpectedIn, ex );
2106 init_class_id(Class_LoadStore);
2108 }
2110 //=============================================================================
2111 //-------------------------------adr_type--------------------------------------
2112 // Do we Match on this edge index or not? Do not match memory
2113 const TypePtr* ClearArrayNode::adr_type() const {
2114 Node *adr = in(3);
2115 return MemNode::calculate_adr_type(adr->bottom_type());
2116 }
2118 //------------------------------match_edge-------------------------------------
2119 // Do we Match on this edge index or not? Do not match memory
2120 uint ClearArrayNode::match_edge(uint idx) const {
2121 return idx > 1;
2122 }
2124 //------------------------------Identity---------------------------------------
2125 // Clearing a zero length array does nothing
2126 Node *ClearArrayNode::Identity( PhaseTransform *phase ) {
2127 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
2128 }
2130 //------------------------------Idealize---------------------------------------
2131 // Clearing a short array is faster with stores
2132 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape){
2133 const int unit = BytesPerLong;
2134 const TypeX* t = phase->type(in(2))->isa_intptr_t();
2135 if (!t) return NULL;
2136 if (!t->is_con()) return NULL;
2137 intptr_t raw_count = t->get_con();
2138 intptr_t size = raw_count;
2139 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
2140 // Clearing nothing uses the Identity call.
2141 // Negative clears are possible on dead ClearArrays
2142 // (see jck test stmt114.stmt11402.val).
2143 if (size <= 0 || size % unit != 0) return NULL;
2144 intptr_t count = size / unit;
2145 // Length too long; use fast hardware clear
2146 if (size > Matcher::init_array_short_size) return NULL;
2147 Node *mem = in(1);
2148 if( phase->type(mem)==Type::TOP ) return NULL;
2149 Node *adr = in(3);
2150 const Type* at = phase->type(adr);
2151 if( at==Type::TOP ) return NULL;
2152 const TypePtr* atp = at->isa_ptr();
2153 // adjust atp to be the correct array element address type
2154 if (atp == NULL) atp = TypePtr::BOTTOM;
2155 else atp = atp->add_offset(Type::OffsetBot);
2156 // Get base for derived pointer purposes
2157 if( adr->Opcode() != Op_AddP ) Unimplemented();
2158 Node *base = adr->in(1);
2160 Node *zero = phase->makecon(TypeLong::ZERO);
2161 Node *off = phase->MakeConX(BytesPerLong);
2162 mem = new (phase->C, 4) StoreLNode(in(0),mem,adr,atp,zero);
2163 count--;
2164 while( count-- ) {
2165 mem = phase->transform(mem);
2166 adr = phase->transform(new (phase->C, 4) AddPNode(base,adr,off));
2167 mem = new (phase->C, 4) StoreLNode(in(0),mem,adr,atp,zero);
2168 }
2169 return mem;
2170 }
2172 //----------------------------clear_memory-------------------------------------
2173 // Generate code to initialize object storage to zero.
2174 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2175 intptr_t start_offset,
2176 Node* end_offset,
2177 PhaseGVN* phase) {
2178 Compile* C = phase->C;
2179 intptr_t offset = start_offset;
2181 int unit = BytesPerLong;
2182 if ((offset % unit) != 0) {
2183 Node* adr = new (C, 4) AddPNode(dest, dest, phase->MakeConX(offset));
2184 adr = phase->transform(adr);
2185 const TypePtr* atp = TypeRawPtr::BOTTOM;
2186 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT);
2187 mem = phase->transform(mem);
2188 offset += BytesPerInt;
2189 }
2190 assert((offset % unit) == 0, "");
2192 // Initialize the remaining stuff, if any, with a ClearArray.
2193 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase);
2194 }
2196 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2197 Node* start_offset,
2198 Node* end_offset,
2199 PhaseGVN* phase) {
2200 if (start_offset == end_offset) {
2201 // nothing to do
2202 return mem;
2203 }
2205 Compile* C = phase->C;
2206 int unit = BytesPerLong;
2207 Node* zbase = start_offset;
2208 Node* zend = end_offset;
2210 // Scale to the unit required by the CPU:
2211 if (!Matcher::init_array_count_is_in_bytes) {
2212 Node* shift = phase->intcon(exact_log2(unit));
2213 zbase = phase->transform( new(C,3) URShiftXNode(zbase, shift) );
2214 zend = phase->transform( new(C,3) URShiftXNode(zend, shift) );
2215 }
2217 Node* zsize = phase->transform( new(C,3) SubXNode(zend, zbase) );
2218 Node* zinit = phase->zerocon((unit == BytesPerLong) ? T_LONG : T_INT);
2220 // Bulk clear double-words
2221 Node* adr = phase->transform( new(C,4) AddPNode(dest, dest, start_offset) );
2222 mem = new (C, 4) ClearArrayNode(ctl, mem, zsize, adr);
2223 return phase->transform(mem);
2224 }
2226 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2227 intptr_t start_offset,
2228 intptr_t end_offset,
2229 PhaseGVN* phase) {
2230 if (start_offset == end_offset) {
2231 // nothing to do
2232 return mem;
2233 }
2235 Compile* C = phase->C;
2236 assert((end_offset % BytesPerInt) == 0, "odd end offset");
2237 intptr_t done_offset = end_offset;
2238 if ((done_offset % BytesPerLong) != 0) {
2239 done_offset -= BytesPerInt;
2240 }
2241 if (done_offset > start_offset) {
2242 mem = clear_memory(ctl, mem, dest,
2243 start_offset, phase->MakeConX(done_offset), phase);
2244 }
2245 if (done_offset < end_offset) { // emit the final 32-bit store
2246 Node* adr = new (C, 4) AddPNode(dest, dest, phase->MakeConX(done_offset));
2247 adr = phase->transform(adr);
2248 const TypePtr* atp = TypeRawPtr::BOTTOM;
2249 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT);
2250 mem = phase->transform(mem);
2251 done_offset += BytesPerInt;
2252 }
2253 assert(done_offset == end_offset, "");
2254 return mem;
2255 }
2257 //=============================================================================
2258 // Do we match on this edge? No memory edges
2259 uint StrCompNode::match_edge(uint idx) const {
2260 return idx == 5 || idx == 6;
2261 }
2263 //------------------------------Ideal------------------------------------------
2264 // Return a node which is more "ideal" than the current node. Strip out
2265 // control copies
2266 Node *StrCompNode::Ideal(PhaseGVN *phase, bool can_reshape){
2267 return remove_dead_region(phase, can_reshape) ? this : NULL;
2268 }
2271 //=============================================================================
2272 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
2273 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)),
2274 _adr_type(C->get_adr_type(alias_idx))
2275 {
2276 init_class_id(Class_MemBar);
2277 Node* top = C->top();
2278 init_req(TypeFunc::I_O,top);
2279 init_req(TypeFunc::FramePtr,top);
2280 init_req(TypeFunc::ReturnAdr,top);
2281 if (precedent != NULL)
2282 init_req(TypeFunc::Parms, precedent);
2283 }
2285 //------------------------------cmp--------------------------------------------
2286 uint MemBarNode::hash() const { return NO_HASH; }
2287 uint MemBarNode::cmp( const Node &n ) const {
2288 return (&n == this); // Always fail except on self
2289 }
2291 //------------------------------make-------------------------------------------
2292 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
2293 int len = Precedent + (pn == NULL? 0: 1);
2294 switch (opcode) {
2295 case Op_MemBarAcquire: return new(C, len) MemBarAcquireNode(C, atp, pn);
2296 case Op_MemBarRelease: return new(C, len) MemBarReleaseNode(C, atp, pn);
2297 case Op_MemBarVolatile: return new(C, len) MemBarVolatileNode(C, atp, pn);
2298 case Op_MemBarCPUOrder: return new(C, len) MemBarCPUOrderNode(C, atp, pn);
2299 case Op_Initialize: return new(C, len) InitializeNode(C, atp, pn);
2300 default: ShouldNotReachHere(); return NULL;
2301 }
2302 }
2304 //------------------------------Ideal------------------------------------------
2305 // Return a node which is more "ideal" than the current node. Strip out
2306 // control copies
2307 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2308 if (remove_dead_region(phase, can_reshape)) return this;
2309 return NULL;
2310 }
2312 //------------------------------Value------------------------------------------
2313 const Type *MemBarNode::Value( PhaseTransform *phase ) const {
2314 if( !in(0) ) return Type::TOP;
2315 if( phase->type(in(0)) == Type::TOP )
2316 return Type::TOP;
2317 return TypeTuple::MEMBAR;
2318 }
2320 //------------------------------match------------------------------------------
2321 // Construct projections for memory.
2322 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) {
2323 switch (proj->_con) {
2324 case TypeFunc::Control:
2325 case TypeFunc::Memory:
2326 return new (m->C, 1) MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
2327 }
2328 ShouldNotReachHere();
2329 return NULL;
2330 }
2332 //===========================InitializeNode====================================
2333 // SUMMARY:
2334 // This node acts as a memory barrier on raw memory, after some raw stores.
2335 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
2336 // The Initialize can 'capture' suitably constrained stores as raw inits.
2337 // It can coalesce related raw stores into larger units (called 'tiles').
2338 // It can avoid zeroing new storage for memory units which have raw inits.
2339 // At macro-expansion, it is marked 'complete', and does not optimize further.
2340 //
2341 // EXAMPLE:
2342 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
2343 // ctl = incoming control; mem* = incoming memory
2344 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
2345 // First allocate uninitialized memory and fill in the header:
2346 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
2347 // ctl := alloc.Control; mem* := alloc.Memory*
2348 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
2349 // Then initialize to zero the non-header parts of the raw memory block:
2350 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
2351 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
2352 // After the initialize node executes, the object is ready for service:
2353 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
2354 // Suppose its body is immediately initialized as {1,2}:
2355 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
2356 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
2357 // mem.SLICE(#short[*]) := store2
2358 //
2359 // DETAILS:
2360 // An InitializeNode collects and isolates object initialization after
2361 // an AllocateNode and before the next possible safepoint. As a
2362 // memory barrier (MemBarNode), it keeps critical stores from drifting
2363 // down past any safepoint or any publication of the allocation.
2364 // Before this barrier, a newly-allocated object may have uninitialized bits.
2365 // After this barrier, it may be treated as a real oop, and GC is allowed.
2366 //
2367 // The semantics of the InitializeNode include an implicit zeroing of
2368 // the new object from object header to the end of the object.
2369 // (The object header and end are determined by the AllocateNode.)
2370 //
2371 // Certain stores may be added as direct inputs to the InitializeNode.
2372 // These stores must update raw memory, and they must be to addresses
2373 // derived from the raw address produced by AllocateNode, and with
2374 // a constant offset. They must be ordered by increasing offset.
2375 // The first one is at in(RawStores), the last at in(req()-1).
2376 // Unlike most memory operations, they are not linked in a chain,
2377 // but are displayed in parallel as users of the rawmem output of
2378 // the allocation.
2379 //
2380 // (See comments in InitializeNode::capture_store, which continue
2381 // the example given above.)
2382 //
2383 // When the associated Allocate is macro-expanded, the InitializeNode
2384 // may be rewritten to optimize collected stores. A ClearArrayNode
2385 // may also be created at that point to represent any required zeroing.
2386 // The InitializeNode is then marked 'complete', prohibiting further
2387 // capturing of nearby memory operations.
2388 //
2389 // During macro-expansion, all captured initializations which store
2390 // constant values of 32 bits or smaller are coalesced (if advantagous)
2391 // into larger 'tiles' 32 or 64 bits. This allows an object to be
2392 // initialized in fewer memory operations. Memory words which are
2393 // covered by neither tiles nor non-constant stores are pre-zeroed
2394 // by explicit stores of zero. (The code shape happens to do all
2395 // zeroing first, then all other stores, with both sequences occurring
2396 // in order of ascending offsets.)
2397 //
2398 // Alternatively, code may be inserted between an AllocateNode and its
2399 // InitializeNode, to perform arbitrary initialization of the new object.
2400 // E.g., the object copying intrinsics insert complex data transfers here.
2401 // The initialization must then be marked as 'complete' disable the
2402 // built-in zeroing semantics and the collection of initializing stores.
2403 //
2404 // While an InitializeNode is incomplete, reads from the memory state
2405 // produced by it are optimizable if they match the control edge and
2406 // new oop address associated with the allocation/initialization.
2407 // They return a stored value (if the offset matches) or else zero.
2408 // A write to the memory state, if it matches control and address,
2409 // and if it is to a constant offset, may be 'captured' by the
2410 // InitializeNode. It is cloned as a raw memory operation and rewired
2411 // inside the initialization, to the raw oop produced by the allocation.
2412 // Operations on addresses which are provably distinct (e.g., to
2413 // other AllocateNodes) are allowed to bypass the initialization.
2414 //
2415 // The effect of all this is to consolidate object initialization
2416 // (both arrays and non-arrays, both piecewise and bulk) into a
2417 // single location, where it can be optimized as a unit.
2418 //
2419 // Only stores with an offset less than TrackedInitializationLimit words
2420 // will be considered for capture by an InitializeNode. This puts a
2421 // reasonable limit on the complexity of optimized initializations.
2423 //---------------------------InitializeNode------------------------------------
2424 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
2425 : _is_complete(false),
2426 MemBarNode(C, adr_type, rawoop)
2427 {
2428 init_class_id(Class_Initialize);
2430 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
2431 assert(in(RawAddress) == rawoop, "proper init");
2432 // Note: allocation() can be NULL, for secondary initialization barriers
2433 }
2435 // Since this node is not matched, it will be processed by the
2436 // register allocator. Declare that there are no constraints
2437 // on the allocation of the RawAddress edge.
2438 const RegMask &InitializeNode::in_RegMask(uint idx) const {
2439 // This edge should be set to top, by the set_complete. But be conservative.
2440 if (idx == InitializeNode::RawAddress)
2441 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
2442 return RegMask::Empty;
2443 }
2445 Node* InitializeNode::memory(uint alias_idx) {
2446 Node* mem = in(Memory);
2447 if (mem->is_MergeMem()) {
2448 return mem->as_MergeMem()->memory_at(alias_idx);
2449 } else {
2450 // incoming raw memory is not split
2451 return mem;
2452 }
2453 }
2455 bool InitializeNode::is_non_zero() {
2456 if (is_complete()) return false;
2457 remove_extra_zeroes();
2458 return (req() > RawStores);
2459 }
2461 void InitializeNode::set_complete(PhaseGVN* phase) {
2462 assert(!is_complete(), "caller responsibility");
2463 _is_complete = true;
2465 // After this node is complete, it contains a bunch of
2466 // raw-memory initializations. There is no need for
2467 // it to have anything to do with non-raw memory effects.
2468 // Therefore, tell all non-raw users to re-optimize themselves,
2469 // after skipping the memory effects of this initialization.
2470 PhaseIterGVN* igvn = phase->is_IterGVN();
2471 if (igvn) igvn->add_users_to_worklist(this);
2472 }
2474 // convenience function
2475 // return false if the init contains any stores already
2476 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
2477 InitializeNode* init = initialization();
2478 if (init == NULL || init->is_complete()) return false;
2479 init->remove_extra_zeroes();
2480 // for now, if this allocation has already collected any inits, bail:
2481 if (init->is_non_zero()) return false;
2482 init->set_complete(phase);
2483 return true;
2484 }
2486 void InitializeNode::remove_extra_zeroes() {
2487 if (req() == RawStores) return;
2488 Node* zmem = zero_memory();
2489 uint fill = RawStores;
2490 for (uint i = fill; i < req(); i++) {
2491 Node* n = in(i);
2492 if (n->is_top() || n == zmem) continue; // skip
2493 if (fill < i) set_req(fill, n); // compact
2494 ++fill;
2495 }
2496 // delete any empty spaces created:
2497 while (fill < req()) {
2498 del_req(fill);
2499 }
2500 }
2502 // Helper for remembering which stores go with which offsets.
2503 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) {
2504 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
2505 intptr_t offset = -1;
2506 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
2507 phase, offset);
2508 if (base == NULL) return -1; // something is dead,
2509 if (offset < 0) return -1; // dead, dead
2510 return offset;
2511 }
2513 // Helper for proving that an initialization expression is
2514 // "simple enough" to be folded into an object initialization.
2515 // Attempts to prove that a store's initial value 'n' can be captured
2516 // within the initialization without creating a vicious cycle, such as:
2517 // { Foo p = new Foo(); p.next = p; }
2518 // True for constants and parameters and small combinations thereof.
2519 bool InitializeNode::detect_init_independence(Node* n,
2520 bool st_is_pinned,
2521 int& count) {
2522 if (n == NULL) return true; // (can this really happen?)
2523 if (n->is_Proj()) n = n->in(0);
2524 if (n == this) return false; // found a cycle
2525 if (n->is_Con()) return true;
2526 if (n->is_Start()) return true; // params, etc., are OK
2527 if (n->is_Root()) return true; // even better
2529 Node* ctl = n->in(0);
2530 if (ctl != NULL && !ctl->is_top()) {
2531 if (ctl->is_Proj()) ctl = ctl->in(0);
2532 if (ctl == this) return false;
2534 // If we already know that the enclosing memory op is pinned right after
2535 // the init, then any control flow that the store has picked up
2536 // must have preceded the init, or else be equal to the init.
2537 // Even after loop optimizations (which might change control edges)
2538 // a store is never pinned *before* the availability of its inputs.
2539 if (!MemNode::detect_dominating_control(ctl, this->in(0)))
2540 return false; // failed to prove a good control
2542 }
2544 // Check data edges for possible dependencies on 'this'.
2545 if ((count += 1) > 20) return false; // complexity limit
2546 for (uint i = 1; i < n->req(); i++) {
2547 Node* m = n->in(i);
2548 if (m == NULL || m == n || m->is_top()) continue;
2549 uint first_i = n->find_edge(m);
2550 if (i != first_i) continue; // process duplicate edge just once
2551 if (!detect_init_independence(m, st_is_pinned, count)) {
2552 return false;
2553 }
2554 }
2556 return true;
2557 }
2559 // Here are all the checks a Store must pass before it can be moved into
2560 // an initialization. Returns zero if a check fails.
2561 // On success, returns the (constant) offset to which the store applies,
2562 // within the initialized memory.
2563 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase) {
2564 const int FAIL = 0;
2565 if (st->req() != MemNode::ValueIn + 1)
2566 return FAIL; // an inscrutable StoreNode (card mark?)
2567 Node* ctl = st->in(MemNode::Control);
2568 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this))
2569 return FAIL; // must be unconditional after the initialization
2570 Node* mem = st->in(MemNode::Memory);
2571 if (!(mem->is_Proj() && mem->in(0) == this))
2572 return FAIL; // must not be preceded by other stores
2573 Node* adr = st->in(MemNode::Address);
2574 intptr_t offset;
2575 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
2576 if (alloc == NULL)
2577 return FAIL; // inscrutable address
2578 if (alloc != allocation())
2579 return FAIL; // wrong allocation! (store needs to float up)
2580 Node* val = st->in(MemNode::ValueIn);
2581 int complexity_count = 0;
2582 if (!detect_init_independence(val, true, complexity_count))
2583 return FAIL; // stored value must be 'simple enough'
2585 return offset; // success
2586 }
2588 // Find the captured store in(i) which corresponds to the range
2589 // [start..start+size) in the initialized object.
2590 // If there is one, return its index i. If there isn't, return the
2591 // negative of the index where it should be inserted.
2592 // Return 0 if the queried range overlaps an initialization boundary
2593 // or if dead code is encountered.
2594 // If size_in_bytes is zero, do not bother with overlap checks.
2595 int InitializeNode::captured_store_insertion_point(intptr_t start,
2596 int size_in_bytes,
2597 PhaseTransform* phase) {
2598 const int FAIL = 0, MAX_STORE = BytesPerLong;
2600 if (is_complete())
2601 return FAIL; // arraycopy got here first; punt
2603 assert(allocation() != NULL, "must be present");
2605 // no negatives, no header fields:
2606 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
2608 // after a certain size, we bail out on tracking all the stores:
2609 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
2610 if (start >= ti_limit) return FAIL;
2612 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
2613 if (i >= limit) return -(int)i; // not found; here is where to put it
2615 Node* st = in(i);
2616 intptr_t st_off = get_store_offset(st, phase);
2617 if (st_off < 0) {
2618 if (st != zero_memory()) {
2619 return FAIL; // bail out if there is dead garbage
2620 }
2621 } else if (st_off > start) {
2622 // ...we are done, since stores are ordered
2623 if (st_off < start + size_in_bytes) {
2624 return FAIL; // the next store overlaps
2625 }
2626 return -(int)i; // not found; here is where to put it
2627 } else if (st_off < start) {
2628 if (size_in_bytes != 0 &&
2629 start < st_off + MAX_STORE &&
2630 start < st_off + st->as_Store()->memory_size()) {
2631 return FAIL; // the previous store overlaps
2632 }
2633 } else {
2634 if (size_in_bytes != 0 &&
2635 st->as_Store()->memory_size() != size_in_bytes) {
2636 return FAIL; // mismatched store size
2637 }
2638 return i;
2639 }
2641 ++i;
2642 }
2643 }
2645 // Look for a captured store which initializes at the offset 'start'
2646 // with the given size. If there is no such store, and no other
2647 // initialization interferes, then return zero_memory (the memory
2648 // projection of the AllocateNode).
2649 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
2650 PhaseTransform* phase) {
2651 assert(stores_are_sane(phase), "");
2652 int i = captured_store_insertion_point(start, size_in_bytes, phase);
2653 if (i == 0) {
2654 return NULL; // something is dead
2655 } else if (i < 0) {
2656 return zero_memory(); // just primordial zero bits here
2657 } else {
2658 Node* st = in(i); // here is the store at this position
2659 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
2660 return st;
2661 }
2662 }
2664 // Create, as a raw pointer, an address within my new object at 'offset'.
2665 Node* InitializeNode::make_raw_address(intptr_t offset,
2666 PhaseTransform* phase) {
2667 Node* addr = in(RawAddress);
2668 if (offset != 0) {
2669 Compile* C = phase->C;
2670 addr = phase->transform( new (C, 4) AddPNode(C->top(), addr,
2671 phase->MakeConX(offset)) );
2672 }
2673 return addr;
2674 }
2676 // Clone the given store, converting it into a raw store
2677 // initializing a field or element of my new object.
2678 // Caller is responsible for retiring the original store,
2679 // with subsume_node or the like.
2680 //
2681 // From the example above InitializeNode::InitializeNode,
2682 // here are the old stores to be captured:
2683 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
2684 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
2685 //
2686 // Here is the changed code; note the extra edges on init:
2687 // alloc = (Allocate ...)
2688 // rawoop = alloc.RawAddress
2689 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
2690 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
2691 // init = (Initialize alloc.Control alloc.Memory rawoop
2692 // rawstore1 rawstore2)
2693 //
2694 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
2695 PhaseTransform* phase) {
2696 assert(stores_are_sane(phase), "");
2698 if (start < 0) return NULL;
2699 assert(can_capture_store(st, phase) == start, "sanity");
2701 Compile* C = phase->C;
2702 int size_in_bytes = st->memory_size();
2703 int i = captured_store_insertion_point(start, size_in_bytes, phase);
2704 if (i == 0) return NULL; // bail out
2705 Node* prev_mem = NULL; // raw memory for the captured store
2706 if (i > 0) {
2707 prev_mem = in(i); // there is a pre-existing store under this one
2708 set_req(i, C->top()); // temporarily disconnect it
2709 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
2710 } else {
2711 i = -i; // no pre-existing store
2712 prev_mem = zero_memory(); // a slice of the newly allocated object
2713 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
2714 set_req(--i, C->top()); // reuse this edge; it has been folded away
2715 else
2716 ins_req(i, C->top()); // build a new edge
2717 }
2718 Node* new_st = st->clone();
2719 new_st->set_req(MemNode::Control, in(Control));
2720 new_st->set_req(MemNode::Memory, prev_mem);
2721 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
2722 new_st = phase->transform(new_st);
2724 // At this point, new_st might have swallowed a pre-existing store
2725 // at the same offset, or perhaps new_st might have disappeared,
2726 // if it redundantly stored the same value (or zero to fresh memory).
2728 // In any case, wire it in:
2729 set_req(i, new_st);
2731 // The caller may now kill the old guy.
2732 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
2733 assert(check_st == new_st || check_st == NULL, "must be findable");
2734 assert(!is_complete(), "");
2735 return new_st;
2736 }
2738 static bool store_constant(jlong* tiles, int num_tiles,
2739 intptr_t st_off, int st_size,
2740 jlong con) {
2741 if ((st_off & (st_size-1)) != 0)
2742 return false; // strange store offset (assume size==2**N)
2743 address addr = (address)tiles + st_off;
2744 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
2745 switch (st_size) {
2746 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
2747 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
2748 case sizeof(jint): *(jint*) addr = (jint) con; break;
2749 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
2750 default: return false; // strange store size (detect size!=2**N here)
2751 }
2752 return true; // return success to caller
2753 }
2755 // Coalesce subword constants into int constants and possibly
2756 // into long constants. The goal, if the CPU permits,
2757 // is to initialize the object with a small number of 64-bit tiles.
2758 // Also, convert floating-point constants to bit patterns.
2759 // Non-constants are not relevant to this pass.
2760 //
2761 // In terms of the running example on InitializeNode::InitializeNode
2762 // and InitializeNode::capture_store, here is the transformation
2763 // of rawstore1 and rawstore2 into rawstore12:
2764 // alloc = (Allocate ...)
2765 // rawoop = alloc.RawAddress
2766 // tile12 = 0x00010002
2767 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
2768 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
2769 //
2770 void
2771 InitializeNode::coalesce_subword_stores(intptr_t header_size,
2772 Node* size_in_bytes,
2773 PhaseGVN* phase) {
2774 Compile* C = phase->C;
2776 assert(stores_are_sane(phase), "");
2777 // Note: After this pass, they are not completely sane,
2778 // since there may be some overlaps.
2780 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
2782 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
2783 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
2784 size_limit = MIN2(size_limit, ti_limit);
2785 size_limit = align_size_up(size_limit, BytesPerLong);
2786 int num_tiles = size_limit / BytesPerLong;
2788 // allocate space for the tile map:
2789 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
2790 jlong tiles_buf[small_len];
2791 Node* nodes_buf[small_len];
2792 jlong inits_buf[small_len];
2793 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
2794 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
2795 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
2796 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
2797 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
2798 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
2799 // tiles: exact bitwise model of all primitive constants
2800 // nodes: last constant-storing node subsumed into the tiles model
2801 // inits: which bytes (in each tile) are touched by any initializations
2803 //// Pass A: Fill in the tile model with any relevant stores.
2805 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
2806 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
2807 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
2808 Node* zmem = zero_memory(); // initially zero memory state
2809 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
2810 Node* st = in(i);
2811 intptr_t st_off = get_store_offset(st, phase);
2813 // Figure out the store's offset and constant value:
2814 if (st_off < header_size) continue; //skip (ignore header)
2815 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
2816 int st_size = st->as_Store()->memory_size();
2817 if (st_off + st_size > size_limit) break;
2819 // Record which bytes are touched, whether by constant or not.
2820 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
2821 continue; // skip (strange store size)
2823 const Type* val = phase->type(st->in(MemNode::ValueIn));
2824 if (!val->singleton()) continue; //skip (non-con store)
2825 BasicType type = val->basic_type();
2827 jlong con = 0;
2828 switch (type) {
2829 case T_INT: con = val->is_int()->get_con(); break;
2830 case T_LONG: con = val->is_long()->get_con(); break;
2831 case T_FLOAT: con = jint_cast(val->getf()); break;
2832 case T_DOUBLE: con = jlong_cast(val->getd()); break;
2833 default: continue; //skip (odd store type)
2834 }
2836 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
2837 st->Opcode() == Op_StoreL) {
2838 continue; // This StoreL is already optimal.
2839 }
2841 // Store down the constant.
2842 store_constant(tiles, num_tiles, st_off, st_size, con);
2844 intptr_t j = st_off >> LogBytesPerLong;
2846 if (type == T_INT && st_size == BytesPerInt
2847 && (st_off & BytesPerInt) == BytesPerInt) {
2848 jlong lcon = tiles[j];
2849 if (!Matcher::isSimpleConstant64(lcon) &&
2850 st->Opcode() == Op_StoreI) {
2851 // This StoreI is already optimal by itself.
2852 jint* intcon = (jint*) &tiles[j];
2853 intcon[1] = 0; // undo the store_constant()
2855 // If the previous store is also optimal by itself, back up and
2856 // undo the action of the previous loop iteration... if we can.
2857 // But if we can't, just let the previous half take care of itself.
2858 st = nodes[j];
2859 st_off -= BytesPerInt;
2860 con = intcon[0];
2861 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) {
2862 assert(st_off >= header_size, "still ignoring header");
2863 assert(get_store_offset(st, phase) == st_off, "must be");
2864 assert(in(i-1) == zmem, "must be");
2865 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
2866 assert(con == tcon->is_int()->get_con(), "must be");
2867 // Undo the effects of the previous loop trip, which swallowed st:
2868 intcon[0] = 0; // undo store_constant()
2869 set_req(i-1, st); // undo set_req(i, zmem)
2870 nodes[j] = NULL; // undo nodes[j] = st
2871 --old_subword; // undo ++old_subword
2872 }
2873 continue; // This StoreI is already optimal.
2874 }
2875 }
2877 // This store is not needed.
2878 set_req(i, zmem);
2879 nodes[j] = st; // record for the moment
2880 if (st_size < BytesPerLong) // something has changed
2881 ++old_subword; // includes int/float, but who's counting...
2882 else ++old_long;
2883 }
2885 if ((old_subword + old_long) == 0)
2886 return; // nothing more to do
2888 //// Pass B: Convert any non-zero tiles into optimal constant stores.
2889 // Be sure to insert them before overlapping non-constant stores.
2890 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
2891 for (int j = 0; j < num_tiles; j++) {
2892 jlong con = tiles[j];
2893 jlong init = inits[j];
2894 if (con == 0) continue;
2895 jint con0, con1; // split the constant, address-wise
2896 jint init0, init1; // split the init map, address-wise
2897 { union { jlong con; jint intcon[2]; } u;
2898 u.con = con;
2899 con0 = u.intcon[0];
2900 con1 = u.intcon[1];
2901 u.con = init;
2902 init0 = u.intcon[0];
2903 init1 = u.intcon[1];
2904 }
2906 Node* old = nodes[j];
2907 assert(old != NULL, "need the prior store");
2908 intptr_t offset = (j * BytesPerLong);
2910 bool split = !Matcher::isSimpleConstant64(con);
2912 if (offset < header_size) {
2913 assert(offset + BytesPerInt >= header_size, "second int counts");
2914 assert(*(jint*)&tiles[j] == 0, "junk in header");
2915 split = true; // only the second word counts
2916 // Example: int a[] = { 42 ... }
2917 } else if (con0 == 0 && init0 == -1) {
2918 split = true; // first word is covered by full inits
2919 // Example: int a[] = { ... foo(), 42 ... }
2920 } else if (con1 == 0 && init1 == -1) {
2921 split = true; // second word is covered by full inits
2922 // Example: int a[] = { ... 42, foo() ... }
2923 }
2925 // Here's a case where init0 is neither 0 nor -1:
2926 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
2927 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
2928 // In this case the tile is not split; it is (jlong)42.
2929 // The big tile is stored down, and then the foo() value is inserted.
2930 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
2932 Node* ctl = old->in(MemNode::Control);
2933 Node* adr = make_raw_address(offset, phase);
2934 const TypePtr* atp = TypeRawPtr::BOTTOM;
2936 // One or two coalesced stores to plop down.
2937 Node* st[2];
2938 intptr_t off[2];
2939 int nst = 0;
2940 if (!split) {
2941 ++new_long;
2942 off[nst] = offset;
2943 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
2944 phase->longcon(con), T_LONG);
2945 } else {
2946 // Omit either if it is a zero.
2947 if (con0 != 0) {
2948 ++new_int;
2949 off[nst] = offset;
2950 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
2951 phase->intcon(con0), T_INT);
2952 }
2953 if (con1 != 0) {
2954 ++new_int;
2955 offset += BytesPerInt;
2956 adr = make_raw_address(offset, phase);
2957 off[nst] = offset;
2958 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
2959 phase->intcon(con1), T_INT);
2960 }
2961 }
2963 // Insert second store first, then the first before the second.
2964 // Insert each one just before any overlapping non-constant stores.
2965 while (nst > 0) {
2966 Node* st1 = st[--nst];
2967 C->copy_node_notes_to(st1, old);
2968 st1 = phase->transform(st1);
2969 offset = off[nst];
2970 assert(offset >= header_size, "do not smash header");
2971 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
2972 guarantee(ins_idx != 0, "must re-insert constant store");
2973 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
2974 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
2975 set_req(--ins_idx, st1);
2976 else
2977 ins_req(ins_idx, st1);
2978 }
2979 }
2981 if (PrintCompilation && WizardMode)
2982 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
2983 old_subword, old_long, new_int, new_long);
2984 if (C->log() != NULL)
2985 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
2986 old_subword, old_long, new_int, new_long);
2988 // Clean up any remaining occurrences of zmem:
2989 remove_extra_zeroes();
2990 }
2992 // Explore forward from in(start) to find the first fully initialized
2993 // word, and return its offset. Skip groups of subword stores which
2994 // together initialize full words. If in(start) is itself part of a
2995 // fully initialized word, return the offset of in(start). If there
2996 // are no following full-word stores, or if something is fishy, return
2997 // a negative value.
2998 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
2999 int int_map = 0;
3000 intptr_t int_map_off = 0;
3001 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
3003 for (uint i = start, limit = req(); i < limit; i++) {
3004 Node* st = in(i);
3006 intptr_t st_off = get_store_offset(st, phase);
3007 if (st_off < 0) break; // return conservative answer
3009 int st_size = st->as_Store()->memory_size();
3010 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
3011 return st_off; // we found a complete word init
3012 }
3014 // update the map:
3016 intptr_t this_int_off = align_size_down(st_off, BytesPerInt);
3017 if (this_int_off != int_map_off) {
3018 // reset the map:
3019 int_map = 0;
3020 int_map_off = this_int_off;
3021 }
3023 int subword_off = st_off - this_int_off;
3024 int_map |= right_n_bits(st_size) << subword_off;
3025 if ((int_map & FULL_MAP) == FULL_MAP) {
3026 return this_int_off; // we found a complete word init
3027 }
3029 // Did this store hit or cross the word boundary?
3030 intptr_t next_int_off = align_size_down(st_off + st_size, BytesPerInt);
3031 if (next_int_off == this_int_off + BytesPerInt) {
3032 // We passed the current int, without fully initializing it.
3033 int_map_off = next_int_off;
3034 int_map >>= BytesPerInt;
3035 } else if (next_int_off > this_int_off + BytesPerInt) {
3036 // We passed the current and next int.
3037 return this_int_off + BytesPerInt;
3038 }
3039 }
3041 return -1;
3042 }
3045 // Called when the associated AllocateNode is expanded into CFG.
3046 // At this point, we may perform additional optimizations.
3047 // Linearize the stores by ascending offset, to make memory
3048 // activity as coherent as possible.
3049 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
3050 intptr_t header_size,
3051 Node* size_in_bytes,
3052 PhaseGVN* phase) {
3053 assert(!is_complete(), "not already complete");
3054 assert(stores_are_sane(phase), "");
3055 assert(allocation() != NULL, "must be present");
3057 remove_extra_zeroes();
3059 if (ReduceFieldZeroing || ReduceBulkZeroing)
3060 // reduce instruction count for common initialization patterns
3061 coalesce_subword_stores(header_size, size_in_bytes, phase);
3063 Node* zmem = zero_memory(); // initially zero memory state
3064 Node* inits = zmem; // accumulating a linearized chain of inits
3065 #ifdef ASSERT
3066 intptr_t first_offset = allocation()->minimum_header_size();
3067 intptr_t last_init_off = first_offset; // previous init offset
3068 intptr_t last_init_end = first_offset; // previous init offset+size
3069 intptr_t last_tile_end = first_offset; // previous tile offset+size
3070 #endif
3071 intptr_t zeroes_done = header_size;
3073 bool do_zeroing = true; // we might give up if inits are very sparse
3074 int big_init_gaps = 0; // how many large gaps have we seen?
3076 if (ZeroTLAB) do_zeroing = false;
3077 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
3079 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3080 Node* st = in(i);
3081 intptr_t st_off = get_store_offset(st, phase);
3082 if (st_off < 0)
3083 break; // unknown junk in the inits
3084 if (st->in(MemNode::Memory) != zmem)
3085 break; // complicated store chains somehow in list
3087 int st_size = st->as_Store()->memory_size();
3088 intptr_t next_init_off = st_off + st_size;
3090 if (do_zeroing && zeroes_done < next_init_off) {
3091 // See if this store needs a zero before it or under it.
3092 intptr_t zeroes_needed = st_off;
3094 if (st_size < BytesPerInt) {
3095 // Look for subword stores which only partially initialize words.
3096 // If we find some, we must lay down some word-level zeroes first,
3097 // underneath the subword stores.
3098 //
3099 // Examples:
3100 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
3101 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
3102 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
3103 //
3104 // Note: coalesce_subword_stores may have already done this,
3105 // if it was prompted by constant non-zero subword initializers.
3106 // But this case can still arise with non-constant stores.
3108 intptr_t next_full_store = find_next_fullword_store(i, phase);
3110 // In the examples above:
3111 // in(i) p q r s x y z
3112 // st_off 12 13 14 15 12 13 14
3113 // st_size 1 1 1 1 1 1 1
3114 // next_full_s. 12 16 16 16 16 16 16
3115 // z's_done 12 16 16 16 12 16 12
3116 // z's_needed 12 16 16 16 16 16 16
3117 // zsize 0 0 0 0 4 0 4
3118 if (next_full_store < 0) {
3119 // Conservative tack: Zero to end of current word.
3120 zeroes_needed = align_size_up(zeroes_needed, BytesPerInt);
3121 } else {
3122 // Zero to beginning of next fully initialized word.
3123 // Or, don't zero at all, if we are already in that word.
3124 assert(next_full_store >= zeroes_needed, "must go forward");
3125 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
3126 zeroes_needed = next_full_store;
3127 }
3128 }
3130 if (zeroes_needed > zeroes_done) {
3131 intptr_t zsize = zeroes_needed - zeroes_done;
3132 // Do some incremental zeroing on rawmem, in parallel with inits.
3133 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3134 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3135 zeroes_done, zeroes_needed,
3136 phase);
3137 zeroes_done = zeroes_needed;
3138 if (zsize > Matcher::init_array_short_size && ++big_init_gaps > 2)
3139 do_zeroing = false; // leave the hole, next time
3140 }
3141 }
3143 // Collect the store and move on:
3144 st->set_req(MemNode::Memory, inits);
3145 inits = st; // put it on the linearized chain
3146 set_req(i, zmem); // unhook from previous position
3148 if (zeroes_done == st_off)
3149 zeroes_done = next_init_off;
3151 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
3153 #ifdef ASSERT
3154 // Various order invariants. Weaker than stores_are_sane because
3155 // a large constant tile can be filled in by smaller non-constant stores.
3156 assert(st_off >= last_init_off, "inits do not reverse");
3157 last_init_off = st_off;
3158 const Type* val = NULL;
3159 if (st_size >= BytesPerInt &&
3160 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
3161 (int)val->basic_type() < (int)T_OBJECT) {
3162 assert(st_off >= last_tile_end, "tiles do not overlap");
3163 assert(st_off >= last_init_end, "tiles do not overwrite inits");
3164 last_tile_end = MAX2(last_tile_end, next_init_off);
3165 } else {
3166 intptr_t st_tile_end = align_size_up(next_init_off, BytesPerLong);
3167 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
3168 assert(st_off >= last_init_end, "inits do not overlap");
3169 last_init_end = next_init_off; // it's a non-tile
3170 }
3171 #endif //ASSERT
3172 }
3174 remove_extra_zeroes(); // clear out all the zmems left over
3175 add_req(inits);
3177 if (!ZeroTLAB) {
3178 // If anything remains to be zeroed, zero it all now.
3179 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3180 // if it is the last unused 4 bytes of an instance, forget about it
3181 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
3182 if (zeroes_done + BytesPerLong >= size_limit) {
3183 assert(allocation() != NULL, "");
3184 Node* klass_node = allocation()->in(AllocateNode::KlassNode);
3185 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass();
3186 if (zeroes_done == k->layout_helper())
3187 zeroes_done = size_limit;
3188 }
3189 if (zeroes_done < size_limit) {
3190 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3191 zeroes_done, size_in_bytes, phase);
3192 }
3193 }
3195 set_complete(phase);
3196 return rawmem;
3197 }
3200 #ifdef ASSERT
3201 bool InitializeNode::stores_are_sane(PhaseTransform* phase) {
3202 if (is_complete())
3203 return true; // stores could be anything at this point
3204 assert(allocation() != NULL, "must be present");
3205 intptr_t last_off = allocation()->minimum_header_size();
3206 for (uint i = InitializeNode::RawStores; i < req(); i++) {
3207 Node* st = in(i);
3208 intptr_t st_off = get_store_offset(st, phase);
3209 if (st_off < 0) continue; // ignore dead garbage
3210 if (last_off > st_off) {
3211 tty->print_cr("*** bad store offset at %d: %d > %d", i, last_off, st_off);
3212 this->dump(2);
3213 assert(false, "ascending store offsets");
3214 return false;
3215 }
3216 last_off = st_off + st->as_Store()->memory_size();
3217 }
3218 return true;
3219 }
3220 #endif //ASSERT
3225 //============================MergeMemNode=====================================
3226 //
3227 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
3228 // contributing store or call operations. Each contributor provides the memory
3229 // state for a particular "alias type" (see Compile::alias_type). For example,
3230 // if a MergeMem has an input X for alias category #6, then any memory reference
3231 // to alias category #6 may use X as its memory state input, as an exact equivalent
3232 // to using the MergeMem as a whole.
3233 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
3234 //
3235 // (Here, the <N> notation gives the index of the relevant adr_type.)
3236 //
3237 // In one special case (and more cases in the future), alias categories overlap.
3238 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
3239 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
3240 // it is exactly equivalent to that state W:
3241 // MergeMem(<Bot>: W) <==> W
3242 //
3243 // Usually, the merge has more than one input. In that case, where inputs
3244 // overlap (i.e., one is Bot), the narrower alias type determines the memory
3245 // state for that type, and the wider alias type (Bot) fills in everywhere else:
3246 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
3247 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
3248 //
3249 // A merge can take a "wide" memory state as one of its narrow inputs.
3250 // This simply means that the merge observes out only the relevant parts of
3251 // the wide input. That is, wide memory states arriving at narrow merge inputs
3252 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
3253 //
3254 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
3255 // and that memory slices "leak through":
3256 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
3257 //
3258 // But, in such a cascade, repeated memory slices can "block the leak":
3259 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
3260 //
3261 // In the last example, Y is not part of the combined memory state of the
3262 // outermost MergeMem. The system must, of course, prevent unschedulable
3263 // memory states from arising, so you can be sure that the state Y is somehow
3264 // a precursor to state Y'.
3265 //
3266 //
3267 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
3268 // of each MergeMemNode array are exactly the numerical alias indexes, including
3269 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
3270 // Compile::alias_type (and kin) produce and manage these indexes.
3271 //
3272 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
3273 // (Note that this provides quick access to the top node inside MergeMem methods,
3274 // without the need to reach out via TLS to Compile::current.)
3275 //
3276 // As a consequence of what was just described, a MergeMem that represents a full
3277 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
3278 // containing all alias categories.
3279 //
3280 // MergeMem nodes never (?) have control inputs, so in(0) is NULL.
3281 //
3282 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
3283 // a memory state for the alias type <N>, or else the top node, meaning that
3284 // there is no particular input for that alias type. Note that the length of
3285 // a MergeMem is variable, and may be extended at any time to accommodate new
3286 // memory states at larger alias indexes. When merges grow, they are of course
3287 // filled with "top" in the unused in() positions.
3288 //
3289 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
3290 // (Top was chosen because it works smoothly with passes like GCM.)
3291 //
3292 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
3293 // the type of random VM bits like TLS references.) Since it is always the
3294 // first non-Bot memory slice, some low-level loops use it to initialize an
3295 // index variable: for (i = AliasIdxRaw; i < req(); i++).
3296 //
3297 //
3298 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
3299 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
3300 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
3301 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
3302 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
3303 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
3304 //
3305 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
3306 // really that different from the other memory inputs. An abbreviation called
3307 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
3308 //
3309 //
3310 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
3311 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
3312 // that "emerges though" the base memory will be marked as excluding the alias types
3313 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
3314 //
3315 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
3316 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
3317 //
3318 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
3319 // (It is currently unimplemented.) As you can see, the resulting merge is
3320 // actually a disjoint union of memory states, rather than an overlay.
3321 //
3323 //------------------------------MergeMemNode-----------------------------------
3324 Node* MergeMemNode::make_empty_memory() {
3325 Node* empty_memory = (Node*) Compile::current()->top();
3326 assert(empty_memory->is_top(), "correct sentinel identity");
3327 return empty_memory;
3328 }
3330 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
3331 init_class_id(Class_MergeMem);
3332 // all inputs are nullified in Node::Node(int)
3333 // set_input(0, NULL); // no control input
3335 // Initialize the edges uniformly to top, for starters.
3336 Node* empty_mem = make_empty_memory();
3337 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
3338 init_req(i,empty_mem);
3339 }
3340 assert(empty_memory() == empty_mem, "");
3342 if( new_base != NULL && new_base->is_MergeMem() ) {
3343 MergeMemNode* mdef = new_base->as_MergeMem();
3344 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
3345 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
3346 mms.set_memory(mms.memory2());
3347 }
3348 assert(base_memory() == mdef->base_memory(), "");
3349 } else {
3350 set_base_memory(new_base);
3351 }
3352 }
3354 // Make a new, untransformed MergeMem with the same base as 'mem'.
3355 // If mem is itself a MergeMem, populate the result with the same edges.
3356 MergeMemNode* MergeMemNode::make(Compile* C, Node* mem) {
3357 return new(C, 1+Compile::AliasIdxRaw) MergeMemNode(mem);
3358 }
3360 //------------------------------cmp--------------------------------------------
3361 uint MergeMemNode::hash() const { return NO_HASH; }
3362 uint MergeMemNode::cmp( const Node &n ) const {
3363 return (&n == this); // Always fail except on self
3364 }
3366 //------------------------------Identity---------------------------------------
3367 Node* MergeMemNode::Identity(PhaseTransform *phase) {
3368 // Identity if this merge point does not record any interesting memory
3369 // disambiguations.
3370 Node* base_mem = base_memory();
3371 Node* empty_mem = empty_memory();
3372 if (base_mem != empty_mem) { // Memory path is not dead?
3373 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3374 Node* mem = in(i);
3375 if (mem != empty_mem && mem != base_mem) {
3376 return this; // Many memory splits; no change
3377 }
3378 }
3379 }
3380 return base_mem; // No memory splits; ID on the one true input
3381 }
3383 //------------------------------Ideal------------------------------------------
3384 // This method is invoked recursively on chains of MergeMem nodes
3385 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3386 // Remove chain'd MergeMems
3387 //
3388 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
3389 // relative to the "in(Bot)". Since we are patching both at the same time,
3390 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
3391 // but rewrite each "in(i)" relative to the new "in(Bot)".
3392 Node *progress = NULL;
3395 Node* old_base = base_memory();
3396 Node* empty_mem = empty_memory();
3397 if (old_base == empty_mem)
3398 return NULL; // Dead memory path.
3400 MergeMemNode* old_mbase;
3401 if (old_base != NULL && old_base->is_MergeMem())
3402 old_mbase = old_base->as_MergeMem();
3403 else
3404 old_mbase = NULL;
3405 Node* new_base = old_base;
3407 // simplify stacked MergeMems in base memory
3408 if (old_mbase) new_base = old_mbase->base_memory();
3410 // the base memory might contribute new slices beyond my req()
3411 if (old_mbase) grow_to_match(old_mbase);
3413 // Look carefully at the base node if it is a phi.
3414 PhiNode* phi_base;
3415 if (new_base != NULL && new_base->is_Phi())
3416 phi_base = new_base->as_Phi();
3417 else
3418 phi_base = NULL;
3420 Node* phi_reg = NULL;
3421 uint phi_len = (uint)-1;
3422 if (phi_base != NULL && !phi_base->is_copy()) {
3423 // do not examine phi if degraded to a copy
3424 phi_reg = phi_base->region();
3425 phi_len = phi_base->req();
3426 // see if the phi is unfinished
3427 for (uint i = 1; i < phi_len; i++) {
3428 if (phi_base->in(i) == NULL) {
3429 // incomplete phi; do not look at it yet!
3430 phi_reg = NULL;
3431 phi_len = (uint)-1;
3432 break;
3433 }
3434 }
3435 }
3437 // Note: We do not call verify_sparse on entry, because inputs
3438 // can normalize to the base_memory via subsume_node or similar
3439 // mechanisms. This method repairs that damage.
3441 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
3443 // Look at each slice.
3444 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3445 Node* old_in = in(i);
3446 // calculate the old memory value
3447 Node* old_mem = old_in;
3448 if (old_mem == empty_mem) old_mem = old_base;
3449 assert(old_mem == memory_at(i), "");
3451 // maybe update (reslice) the old memory value
3453 // simplify stacked MergeMems
3454 Node* new_mem = old_mem;
3455 MergeMemNode* old_mmem;
3456 if (old_mem != NULL && old_mem->is_MergeMem())
3457 old_mmem = old_mem->as_MergeMem();
3458 else
3459 old_mmem = NULL;
3460 if (old_mmem == this) {
3461 // This can happen if loops break up and safepoints disappear.
3462 // A merge of BotPtr (default) with a RawPtr memory derived from a
3463 // safepoint can be rewritten to a merge of the same BotPtr with
3464 // the BotPtr phi coming into the loop. If that phi disappears
3465 // also, we can end up with a self-loop of the mergemem.
3466 // In general, if loops degenerate and memory effects disappear,
3467 // a mergemem can be left looking at itself. This simply means
3468 // that the mergemem's default should be used, since there is
3469 // no longer any apparent effect on this slice.
3470 // Note: If a memory slice is a MergeMem cycle, it is unreachable
3471 // from start. Update the input to TOP.
3472 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
3473 }
3474 else if (old_mmem != NULL) {
3475 new_mem = old_mmem->memory_at(i);
3476 }
3477 // else preceeding memory was not a MergeMem
3479 // replace equivalent phis (unfortunately, they do not GVN together)
3480 if (new_mem != NULL && new_mem != new_base &&
3481 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) {
3482 if (new_mem->is_Phi()) {
3483 PhiNode* phi_mem = new_mem->as_Phi();
3484 for (uint i = 1; i < phi_len; i++) {
3485 if (phi_base->in(i) != phi_mem->in(i)) {
3486 phi_mem = NULL;
3487 break;
3488 }
3489 }
3490 if (phi_mem != NULL) {
3491 // equivalent phi nodes; revert to the def
3492 new_mem = new_base;
3493 }
3494 }
3495 }
3497 // maybe store down a new value
3498 Node* new_in = new_mem;
3499 if (new_in == new_base) new_in = empty_mem;
3501 if (new_in != old_in) {
3502 // Warning: Do not combine this "if" with the previous "if"
3503 // A memory slice might have be be rewritten even if it is semantically
3504 // unchanged, if the base_memory value has changed.
3505 set_req(i, new_in);
3506 progress = this; // Report progress
3507 }
3508 }
3510 if (new_base != old_base) {
3511 set_req(Compile::AliasIdxBot, new_base);
3512 // Don't use set_base_memory(new_base), because we need to update du.
3513 assert(base_memory() == new_base, "");
3514 progress = this;
3515 }
3517 if( base_memory() == this ) {
3518 // a self cycle indicates this memory path is dead
3519 set_req(Compile::AliasIdxBot, empty_mem);
3520 }
3522 // Resolve external cycles by calling Ideal on a MergeMem base_memory
3523 // Recursion must occur after the self cycle check above
3524 if( base_memory()->is_MergeMem() ) {
3525 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
3526 Node *m = phase->transform(new_mbase); // Rollup any cycles
3527 if( m != NULL && (m->is_top() ||
3528 m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem) ) {
3529 // propagate rollup of dead cycle to self
3530 set_req(Compile::AliasIdxBot, empty_mem);
3531 }
3532 }
3534 if( base_memory() == empty_mem ) {
3535 progress = this;
3536 // Cut inputs during Parse phase only.
3537 // During Optimize phase a dead MergeMem node will be subsumed by Top.
3538 if( !can_reshape ) {
3539 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3540 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
3541 }
3542 }
3543 }
3545 if( !progress && base_memory()->is_Phi() && can_reshape ) {
3546 // Check if PhiNode::Ideal's "Split phis through memory merges"
3547 // transform should be attempted. Look for this->phi->this cycle.
3548 uint merge_width = req();
3549 if (merge_width > Compile::AliasIdxRaw) {
3550 PhiNode* phi = base_memory()->as_Phi();
3551 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
3552 if (phi->in(i) == this) {
3553 phase->is_IterGVN()->_worklist.push(phi);
3554 break;
3555 }
3556 }
3557 }
3558 }
3560 assert(progress || verify_sparse(), "please, no dups of base");
3561 return progress;
3562 }
3564 //-------------------------set_base_memory-------------------------------------
3565 void MergeMemNode::set_base_memory(Node *new_base) {
3566 Node* empty_mem = empty_memory();
3567 set_req(Compile::AliasIdxBot, new_base);
3568 assert(memory_at(req()) == new_base, "must set default memory");
3569 // Clear out other occurrences of new_base:
3570 if (new_base != empty_mem) {
3571 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3572 if (in(i) == new_base) set_req(i, empty_mem);
3573 }
3574 }
3575 }
3577 //------------------------------out_RegMask------------------------------------
3578 const RegMask &MergeMemNode::out_RegMask() const {
3579 return RegMask::Empty;
3580 }
3582 //------------------------------dump_spec--------------------------------------
3583 #ifndef PRODUCT
3584 void MergeMemNode::dump_spec(outputStream *st) const {
3585 st->print(" {");
3586 Node* base_mem = base_memory();
3587 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
3588 Node* mem = memory_at(i);
3589 if (mem == base_mem) { st->print(" -"); continue; }
3590 st->print( " N%d:", mem->_idx );
3591 Compile::current()->get_adr_type(i)->dump_on(st);
3592 }
3593 st->print(" }");
3594 }
3595 #endif // !PRODUCT
3598 #ifdef ASSERT
3599 static bool might_be_same(Node* a, Node* b) {
3600 if (a == b) return true;
3601 if (!(a->is_Phi() || b->is_Phi())) return false;
3602 // phis shift around during optimization
3603 return true; // pretty stupid...
3604 }
3606 // verify a narrow slice (either incoming or outgoing)
3607 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
3608 if (!VerifyAliases) return; // don't bother to verify unless requested
3609 if (is_error_reported()) return; // muzzle asserts when debugging an error
3610 if (Node::in_dump()) return; // muzzle asserts when printing
3611 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
3612 assert(n != NULL, "");
3613 // Elide intervening MergeMem's
3614 while (n->is_MergeMem()) {
3615 n = n->as_MergeMem()->memory_at(alias_idx);
3616 }
3617 Compile* C = Compile::current();
3618 const TypePtr* n_adr_type = n->adr_type();
3619 if (n == m->empty_memory()) {
3620 // Implicit copy of base_memory()
3621 } else if (n_adr_type != TypePtr::BOTTOM) {
3622 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type");
3623 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
3624 } else {
3625 // A few places like make_runtime_call "know" that VM calls are narrow,
3626 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
3627 bool expected_wide_mem = false;
3628 if (n == m->base_memory()) {
3629 expected_wide_mem = true;
3630 } else if (alias_idx == Compile::AliasIdxRaw ||
3631 n == m->memory_at(Compile::AliasIdxRaw)) {
3632 expected_wide_mem = true;
3633 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
3634 // memory can "leak through" calls on channels that
3635 // are write-once. Allow this also.
3636 expected_wide_mem = true;
3637 }
3638 assert(expected_wide_mem, "expected narrow slice replacement");
3639 }
3640 }
3641 #else // !ASSERT
3642 #define verify_memory_slice(m,i,n) (0) // PRODUCT version is no-op
3643 #endif
3646 //-----------------------------memory_at---------------------------------------
3647 Node* MergeMemNode::memory_at(uint alias_idx) const {
3648 assert(alias_idx >= Compile::AliasIdxRaw ||
3649 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0,
3650 "must avoid base_memory and AliasIdxTop");
3652 // Otherwise, it is a narrow slice.
3653 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
3654 Compile *C = Compile::current();
3655 if (is_empty_memory(n)) {
3656 // the array is sparse; empty slots are the "top" node
3657 n = base_memory();
3658 assert(Node::in_dump()
3659 || n == NULL || n->bottom_type() == Type::TOP
3660 || n->adr_type() == TypePtr::BOTTOM
3661 || n->adr_type() == TypeRawPtr::BOTTOM
3662 || Compile::current()->AliasLevel() == 0,
3663 "must be a wide memory");
3664 // AliasLevel == 0 if we are organizing the memory states manually.
3665 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
3666 } else {
3667 // make sure the stored slice is sane
3668 #ifdef ASSERT
3669 if (is_error_reported() || Node::in_dump()) {
3670 } else if (might_be_same(n, base_memory())) {
3671 // Give it a pass: It is a mostly harmless repetition of the base.
3672 // This can arise normally from node subsumption during optimization.
3673 } else {
3674 verify_memory_slice(this, alias_idx, n);
3675 }
3676 #endif
3677 }
3678 return n;
3679 }
3681 //---------------------------set_memory_at-------------------------------------
3682 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
3683 verify_memory_slice(this, alias_idx, n);
3684 Node* empty_mem = empty_memory();
3685 if (n == base_memory()) n = empty_mem; // collapse default
3686 uint need_req = alias_idx+1;
3687 if (req() < need_req) {
3688 if (n == empty_mem) return; // already the default, so do not grow me
3689 // grow the sparse array
3690 do {
3691 add_req(empty_mem);
3692 } while (req() < need_req);
3693 }
3694 set_req( alias_idx, n );
3695 }
3699 //--------------------------iteration_setup------------------------------------
3700 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
3701 if (other != NULL) {
3702 grow_to_match(other);
3703 // invariant: the finite support of mm2 is within mm->req()
3704 #ifdef ASSERT
3705 for (uint i = req(); i < other->req(); i++) {
3706 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
3707 }
3708 #endif
3709 }
3710 // Replace spurious copies of base_memory by top.
3711 Node* base_mem = base_memory();
3712 if (base_mem != NULL && !base_mem->is_top()) {
3713 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
3714 if (in(i) == base_mem)
3715 set_req(i, empty_memory());
3716 }
3717 }
3718 }
3720 //---------------------------grow_to_match-------------------------------------
3721 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
3722 Node* empty_mem = empty_memory();
3723 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
3724 // look for the finite support of the other memory
3725 for (uint i = other->req(); --i >= req(); ) {
3726 if (other->in(i) != empty_mem) {
3727 uint new_len = i+1;
3728 while (req() < new_len) add_req(empty_mem);
3729 break;
3730 }
3731 }
3732 }
3734 //---------------------------verify_sparse-------------------------------------
3735 #ifndef PRODUCT
3736 bool MergeMemNode::verify_sparse() const {
3737 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
3738 Node* base_mem = base_memory();
3739 // The following can happen in degenerate cases, since empty==top.
3740 if (is_empty_memory(base_mem)) return true;
3741 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3742 assert(in(i) != NULL, "sane slice");
3743 if (in(i) == base_mem) return false; // should have been the sentinel value!
3744 }
3745 return true;
3746 }
3748 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
3749 Node* n;
3750 n = mm->in(idx);
3751 if (mem == n) return true; // might be empty_memory()
3752 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
3753 if (mem == n) return true;
3754 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) {
3755 if (mem == n) return true;
3756 if (n == NULL) break;
3757 }
3758 return false;
3759 }
3760 #endif // !PRODUCT