Mercurial > hg > graal-compiler
comparison src/share/vm/opto/memnode.cpp @ 0:a61af66fc99e jdk7-b24
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author | duke |
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date | Sat, 01 Dec 2007 00:00:00 +0000 |
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children | ff5961f4c095 |
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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 | |
6 * under the terms of the GNU General Public License version 2 only, as | |
7 * published by the Free Software Foundation. | |
8 * | |
9 * This code is distributed in the hope that it will be useful, but WITHOUT | |
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
12 * version 2 for more details (a copy is included in the LICENSE file that | |
13 * accompanied this code). | |
14 * | |
15 * You should have received a copy of the GNU General Public License version | |
16 * 2 along with this work; if not, write to the Free Software Foundation, | |
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
18 * | |
19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, | |
20 * CA 95054 USA or visit www.sun.com if you need additional information or | |
21 * have any questions. | |
22 * | |
23 */ | |
24 | |
25 // Portions of code courtesy of Clifford Click | |
26 | |
27 // Optimization - Graph Style | |
28 | |
29 #include "incls/_precompiled.incl" | |
30 #include "incls/_memnode.cpp.incl" | |
31 | |
32 //============================================================================= | |
33 uint MemNode::size_of() const { return sizeof(*this); } | |
34 | |
35 const TypePtr *MemNode::adr_type() const { | |
36 Node* adr = in(Address); | |
37 const TypePtr* cross_check = NULL; | |
38 DEBUG_ONLY(cross_check = _adr_type); | |
39 return calculate_adr_type(adr->bottom_type(), cross_check); | |
40 } | |
41 | |
42 #ifndef PRODUCT | |
43 void MemNode::dump_spec(outputStream *st) const { | |
44 if (in(Address) == NULL) return; // node is dead | |
45 #ifndef ASSERT | |
46 // fake the missing field | |
47 const TypePtr* _adr_type = NULL; | |
48 if (in(Address) != NULL) | |
49 _adr_type = in(Address)->bottom_type()->isa_ptr(); | |
50 #endif | |
51 dump_adr_type(this, _adr_type, st); | |
52 | |
53 Compile* C = Compile::current(); | |
54 if( C->alias_type(_adr_type)->is_volatile() ) | |
55 st->print(" Volatile!"); | |
56 } | |
57 | |
58 void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) { | |
59 st->print(" @"); | |
60 if (adr_type == NULL) { | |
61 st->print("NULL"); | |
62 } else { | |
63 adr_type->dump_on(st); | |
64 Compile* C = Compile::current(); | |
65 Compile::AliasType* atp = NULL; | |
66 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type); | |
67 if (atp == NULL) | |
68 st->print(", idx=?\?;"); | |
69 else if (atp->index() == Compile::AliasIdxBot) | |
70 st->print(", idx=Bot;"); | |
71 else if (atp->index() == Compile::AliasIdxTop) | |
72 st->print(", idx=Top;"); | |
73 else if (atp->index() == Compile::AliasIdxRaw) | |
74 st->print(", idx=Raw;"); | |
75 else { | |
76 ciField* field = atp->field(); | |
77 if (field) { | |
78 st->print(", name="); | |
79 field->print_name_on(st); | |
80 } | |
81 st->print(", idx=%d;", atp->index()); | |
82 } | |
83 } | |
84 } | |
85 | |
86 extern void print_alias_types(); | |
87 | |
88 #endif | |
89 | |
90 //--------------------------Ideal_common--------------------------------------- | |
91 // Look for degenerate control and memory inputs. Bypass MergeMem inputs. | |
92 // Unhook non-raw memories from complete (macro-expanded) initializations. | |
93 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) { | |
94 // If our control input is a dead region, kill all below the region | |
95 Node *ctl = in(MemNode::Control); | |
96 if (ctl && remove_dead_region(phase, can_reshape)) | |
97 return this; | |
98 | |
99 // Ignore if memory is dead, or self-loop | |
100 Node *mem = in(MemNode::Memory); | |
101 if( phase->type( mem ) == Type::TOP ) return NodeSentinel; // caller will return NULL | |
102 assert( mem != this, "dead loop in MemNode::Ideal" ); | |
103 | |
104 Node *address = in(MemNode::Address); | |
105 const Type *t_adr = phase->type( address ); | |
106 if( t_adr == Type::TOP ) return NodeSentinel; // caller will return NULL | |
107 | |
108 // Avoid independent memory operations | |
109 Node* old_mem = mem; | |
110 | |
111 if (mem->is_Proj() && mem->in(0)->is_Initialize()) { | |
112 InitializeNode* init = mem->in(0)->as_Initialize(); | |
113 if (init->is_complete()) { // i.e., after macro expansion | |
114 const TypePtr* tp = t_adr->is_ptr(); | |
115 uint alias_idx = phase->C->get_alias_index(tp); | |
116 // Free this slice from the init. It was hooked, temporarily, | |
117 // by GraphKit::set_output_for_allocation. | |
118 if (alias_idx > Compile::AliasIdxRaw) { | |
119 mem = init->memory(alias_idx); | |
120 // ...but not with the raw-pointer slice. | |
121 } | |
122 } | |
123 } | |
124 | |
125 if (mem->is_MergeMem()) { | |
126 MergeMemNode* mmem = mem->as_MergeMem(); | |
127 const TypePtr *tp = t_adr->is_ptr(); | |
128 uint alias_idx = phase->C->get_alias_index(tp); | |
129 #ifdef ASSERT | |
130 { | |
131 // Check that current type is consistent with the alias index used during graph construction | |
132 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx"); | |
133 const TypePtr *adr_t = adr_type(); | |
134 bool consistent = adr_t == NULL || adr_t->empty() || phase->C->must_alias(adr_t, alias_idx ); | |
135 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3] | |
136 if( !consistent && adr_t != NULL && !adr_t->empty() && | |
137 tp->isa_aryptr() && tp->offset() == Type::OffsetBot && | |
138 adr_t->isa_aryptr() && adr_t->offset() != Type::OffsetBot && | |
139 ( adr_t->offset() == arrayOopDesc::length_offset_in_bytes() || | |
140 adr_t->offset() == oopDesc::klass_offset_in_bytes() || | |
141 adr_t->offset() == oopDesc::mark_offset_in_bytes() ) ) { | |
142 // don't assert if it is dead code. | |
143 consistent = true; | |
144 } | |
145 if( !consistent ) { | |
146 tty->print("alias_idx==%d, adr_type()==", alias_idx); if( adr_t == NULL ) { tty->print("NULL"); } else { adr_t->dump(); } | |
147 tty->cr(); | |
148 print_alias_types(); | |
149 assert(consistent, "adr_type must match alias idx"); | |
150 } | |
151 } | |
152 #endif | |
153 // TypeInstPtr::NOTNULL+any is an OOP with unknown offset - generally | |
154 // means an array I have not precisely typed yet. Do not do any | |
155 // alias stuff with it any time soon. | |
156 const TypeInstPtr *tinst = tp->isa_instptr(); | |
157 if( tp->base() != Type::AnyPtr && | |
158 !(tinst && | |
159 tinst->klass()->is_java_lang_Object() && | |
160 tinst->offset() == Type::OffsetBot) ) { | |
161 // compress paths and change unreachable cycles to TOP | |
162 // If not, we can update the input infinitely along a MergeMem cycle | |
163 // Equivalent code in PhiNode::Ideal | |
164 Node* m = phase->transform(mmem); | |
165 // If tranformed to a MergeMem, get the desired slice | |
166 // Otherwise the returned node represents memory for every slice | |
167 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m; | |
168 // Update input if it is progress over what we have now | |
169 } | |
170 } | |
171 | |
172 if (mem != old_mem) { | |
173 set_req(MemNode::Memory, mem); | |
174 return this; | |
175 } | |
176 | |
177 // let the subclass continue analyzing... | |
178 return NULL; | |
179 } | |
180 | |
181 // Helper function for proving some simple control dominations. | |
182 // Attempt to prove that control input 'dom' dominates (or equals) 'sub'. | |
183 // Already assumes that 'dom' is available at 'sub', and that 'sub' | |
184 // is not a constant (dominated by the method's StartNode). | |
185 // Used by MemNode::find_previous_store to prove that the | |
186 // control input of a memory operation predates (dominates) | |
187 // an allocation it wants to look past. | |
188 bool MemNode::detect_dominating_control(Node* dom, Node* sub) { | |
189 if (dom == NULL) return false; | |
190 if (dom->is_Proj()) dom = dom->in(0); | |
191 if (dom->is_Start()) return true; // anything inside the method | |
192 if (dom->is_Root()) return true; // dom 'controls' a constant | |
193 int cnt = 20; // detect cycle or too much effort | |
194 while (sub != NULL) { // walk 'sub' up the chain to 'dom' | |
195 if (--cnt < 0) return false; // in a cycle or too complex | |
196 if (sub == dom) return true; | |
197 if (sub->is_Start()) return false; | |
198 if (sub->is_Root()) return false; | |
199 Node* up = sub->in(0); | |
200 if (sub == up && sub->is_Region()) { | |
201 for (uint i = 1; i < sub->req(); i++) { | |
202 Node* in = sub->in(i); | |
203 if (in != NULL && !in->is_top() && in != sub) { | |
204 up = in; break; // take any path on the way up to 'dom' | |
205 } | |
206 } | |
207 } | |
208 if (sub == up) return false; // some kind of tight cycle | |
209 sub = up; | |
210 } | |
211 return false; | |
212 } | |
213 | |
214 //---------------------detect_ptr_independence--------------------------------- | |
215 // Used by MemNode::find_previous_store to prove that two base | |
216 // pointers are never equal. | |
217 // The pointers are accompanied by their associated allocations, | |
218 // if any, which have been previously discovered by the caller. | |
219 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1, | |
220 Node* p2, AllocateNode* a2, | |
221 PhaseTransform* phase) { | |
222 // Attempt to prove that these two pointers cannot be aliased. | |
223 // They may both manifestly be allocations, and they should differ. | |
224 // Or, if they are not both allocations, they can be distinct constants. | |
225 // Otherwise, one is an allocation and the other a pre-existing value. | |
226 if (a1 == NULL && a2 == NULL) { // neither an allocation | |
227 return (p1 != p2) && p1->is_Con() && p2->is_Con(); | |
228 } else if (a1 != NULL && a2 != NULL) { // both allocations | |
229 return (a1 != a2); | |
230 } else if (a1 != NULL) { // one allocation a1 | |
231 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.) | |
232 return detect_dominating_control(p2->in(0), a1->in(0)); | |
233 } else { //(a2 != NULL) // one allocation a2 | |
234 return detect_dominating_control(p1->in(0), a2->in(0)); | |
235 } | |
236 return false; | |
237 } | |
238 | |
239 | |
240 // The logic for reordering loads and stores uses four steps: | |
241 // (a) Walk carefully past stores and initializations which we | |
242 // can prove are independent of this load. | |
243 // (b) Observe that the next memory state makes an exact match | |
244 // with self (load or store), and locate the relevant store. | |
245 // (c) Ensure that, if we were to wire self directly to the store, | |
246 // the optimizer would fold it up somehow. | |
247 // (d) Do the rewiring, and return, depending on some other part of | |
248 // the optimizer to fold up the load. | |
249 // This routine handles steps (a) and (b). Steps (c) and (d) are | |
250 // specific to loads and stores, so they are handled by the callers. | |
251 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.) | |
252 // | |
253 Node* MemNode::find_previous_store(PhaseTransform* phase) { | |
254 Node* ctrl = in(MemNode::Control); | |
255 Node* adr = in(MemNode::Address); | |
256 intptr_t offset = 0; | |
257 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); | |
258 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase); | |
259 | |
260 if (offset == Type::OffsetBot) | |
261 return NULL; // cannot unalias unless there are precise offsets | |
262 | |
263 intptr_t size_in_bytes = memory_size(); | |
264 | |
265 Node* mem = in(MemNode::Memory); // start searching here... | |
266 | |
267 int cnt = 50; // Cycle limiter | |
268 for (;;) { // While we can dance past unrelated stores... | |
269 if (--cnt < 0) break; // Caught in cycle or a complicated dance? | |
270 | |
271 if (mem->is_Store()) { | |
272 Node* st_adr = mem->in(MemNode::Address); | |
273 intptr_t st_offset = 0; | |
274 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset); | |
275 if (st_base == NULL) | |
276 break; // inscrutable pointer | |
277 if (st_offset != offset && st_offset != Type::OffsetBot) { | |
278 const int MAX_STORE = BytesPerLong; | |
279 if (st_offset >= offset + size_in_bytes || | |
280 st_offset <= offset - MAX_STORE || | |
281 st_offset <= offset - mem->as_Store()->memory_size()) { | |
282 // Success: The offsets are provably independent. | |
283 // (You may ask, why not just test st_offset != offset and be done? | |
284 // The answer is that stores of different sizes can co-exist | |
285 // in the same sequence of RawMem effects. We sometimes initialize | |
286 // a whole 'tile' of array elements with a single jint or jlong.) | |
287 mem = mem->in(MemNode::Memory); | |
288 continue; // (a) advance through independent store memory | |
289 } | |
290 } | |
291 if (st_base != base && | |
292 detect_ptr_independence(base, alloc, | |
293 st_base, | |
294 AllocateNode::Ideal_allocation(st_base, phase), | |
295 phase)) { | |
296 // Success: The bases are provably independent. | |
297 mem = mem->in(MemNode::Memory); | |
298 continue; // (a) advance through independent store memory | |
299 } | |
300 | |
301 // (b) At this point, if the bases or offsets do not agree, we lose, | |
302 // since we have not managed to prove 'this' and 'mem' independent. | |
303 if (st_base == base && st_offset == offset) { | |
304 return mem; // let caller handle steps (c), (d) | |
305 } | |
306 | |
307 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) { | |
308 InitializeNode* st_init = mem->in(0)->as_Initialize(); | |
309 AllocateNode* st_alloc = st_init->allocation(); | |
310 if (st_alloc == NULL) | |
311 break; // something degenerated | |
312 bool known_identical = false; | |
313 bool known_independent = false; | |
314 if (alloc == st_alloc) | |
315 known_identical = true; | |
316 else if (alloc != NULL) | |
317 known_independent = true; | |
318 else if (ctrl != NULL && | |
319 detect_dominating_control(ctrl, st_alloc->in(0))) | |
320 known_independent = true; | |
321 | |
322 if (known_independent) { | |
323 // The bases are provably independent: Either they are | |
324 // manifestly distinct allocations, or else the control | |
325 // of this load dominates the store's allocation. | |
326 int alias_idx = phase->C->get_alias_index(adr_type()); | |
327 if (alias_idx == Compile::AliasIdxRaw) { | |
328 mem = st_alloc->in(TypeFunc::Memory); | |
329 } else { | |
330 mem = st_init->memory(alias_idx); | |
331 } | |
332 continue; // (a) advance through independent store memory | |
333 } | |
334 | |
335 // (b) at this point, if we are not looking at a store initializing | |
336 // the same allocation we are loading from, we lose. | |
337 if (known_identical) { | |
338 // From caller, can_see_stored_value will consult find_captured_store. | |
339 return mem; // let caller handle steps (c), (d) | |
340 } | |
341 | |
342 } | |
343 | |
344 // Unless there is an explicit 'continue', we must bail out here, | |
345 // because 'mem' is an inscrutable memory state (e.g., a call). | |
346 break; | |
347 } | |
348 | |
349 return NULL; // bail out | |
350 } | |
351 | |
352 //----------------------calculate_adr_type------------------------------------- | |
353 // Helper function. Notices when the given type of address hits top or bottom. | |
354 // Also, asserts a cross-check of the type against the expected address type. | |
355 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) { | |
356 if (t == Type::TOP) return NULL; // does not touch memory any more? | |
357 #ifdef PRODUCT | |
358 cross_check = NULL; | |
359 #else | |
360 if (!VerifyAliases || is_error_reported() || Node::in_dump()) cross_check = NULL; | |
361 #endif | |
362 const TypePtr* tp = t->isa_ptr(); | |
363 if (tp == NULL) { | |
364 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide"); | |
365 return TypePtr::BOTTOM; // touches lots of memory | |
366 } else { | |
367 #ifdef ASSERT | |
368 // %%%% [phh] We don't check the alias index if cross_check is | |
369 // TypeRawPtr::BOTTOM. Needs to be investigated. | |
370 if (cross_check != NULL && | |
371 cross_check != TypePtr::BOTTOM && | |
372 cross_check != TypeRawPtr::BOTTOM) { | |
373 // Recheck the alias index, to see if it has changed (due to a bug). | |
374 Compile* C = Compile::current(); | |
375 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp), | |
376 "must stay in the original alias category"); | |
377 // The type of the address must be contained in the adr_type, | |
378 // disregarding "null"-ness. | |
379 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.) | |
380 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr(); | |
381 assert(cross_check->meet(tp_notnull) == cross_check, | |
382 "real address must not escape from expected memory type"); | |
383 } | |
384 #endif | |
385 return tp; | |
386 } | |
387 } | |
388 | |
389 //------------------------adr_phi_is_loop_invariant---------------------------- | |
390 // A helper function for Ideal_DU_postCCP to check if a Phi in a counted | |
391 // loop is loop invariant. Make a quick traversal of Phi and associated | |
392 // CastPP nodes, looking to see if they are a closed group within the loop. | |
393 bool MemNode::adr_phi_is_loop_invariant(Node* adr_phi, Node* cast) { | |
394 // The idea is that the phi-nest must boil down to only CastPP nodes | |
395 // with the same data. This implies that any path into the loop already | |
396 // includes such a CastPP, and so the original cast, whatever its input, | |
397 // must be covered by an equivalent cast, with an earlier control input. | |
398 ResourceMark rm; | |
399 | |
400 // The loop entry input of the phi should be the unique dominating | |
401 // node for every Phi/CastPP in the loop. | |
402 Unique_Node_List closure; | |
403 closure.push(adr_phi->in(LoopNode::EntryControl)); | |
404 | |
405 // Add the phi node and the cast to the worklist. | |
406 Unique_Node_List worklist; | |
407 worklist.push(adr_phi); | |
408 if( cast != NULL ){ | |
409 if( !cast->is_ConstraintCast() ) return false; | |
410 worklist.push(cast); | |
411 } | |
412 | |
413 // Begin recursive walk of phi nodes. | |
414 while( worklist.size() ){ | |
415 // Take a node off the worklist | |
416 Node *n = worklist.pop(); | |
417 if( !closure.member(n) ){ | |
418 // Add it to the closure. | |
419 closure.push(n); | |
420 // Make a sanity check to ensure we don't waste too much time here. | |
421 if( closure.size() > 20) return false; | |
422 // This node is OK if: | |
423 // - it is a cast of an identical value | |
424 // - or it is a phi node (then we add its inputs to the worklist) | |
425 // Otherwise, the node is not OK, and we presume the cast is not invariant | |
426 if( n->is_ConstraintCast() ){ | |
427 worklist.push(n->in(1)); | |
428 } else if( n->is_Phi() ) { | |
429 for( uint i = 1; i < n->req(); i++ ) { | |
430 worklist.push(n->in(i)); | |
431 } | |
432 } else { | |
433 return false; | |
434 } | |
435 } | |
436 } | |
437 | |
438 // Quit when the worklist is empty, and we've found no offending nodes. | |
439 return true; | |
440 } | |
441 | |
442 //------------------------------Ideal_DU_postCCP------------------------------- | |
443 // Find any cast-away of null-ness and keep its control. Null cast-aways are | |
444 // going away in this pass and we need to make this memory op depend on the | |
445 // gating null check. | |
446 | |
447 // I tried to leave the CastPP's in. This makes the graph more accurate in | |
448 // some sense; we get to keep around the knowledge that an oop is not-null | |
449 // after some test. Alas, the CastPP's interfere with GVN (some values are | |
450 // the regular oop, some are the CastPP of the oop, all merge at Phi's which | |
451 // cannot collapse, etc). This cost us 10% on SpecJVM, even when I removed | |
452 // some of the more trivial cases in the optimizer. Removing more useless | |
453 // Phi's started allowing Loads to illegally float above null checks. I gave | |
454 // up on this approach. CNC 10/20/2000 | |
455 Node *MemNode::Ideal_DU_postCCP( PhaseCCP *ccp ) { | |
456 Node *ctr = in(MemNode::Control); | |
457 Node *mem = in(MemNode::Memory); | |
458 Node *adr = in(MemNode::Address); | |
459 Node *skipped_cast = NULL; | |
460 // Need a null check? Regular static accesses do not because they are | |
461 // from constant addresses. Array ops are gated by the range check (which | |
462 // always includes a NULL check). Just check field ops. | |
463 if( !ctr ) { | |
464 // Scan upwards for the highest location we can place this memory op. | |
465 while( true ) { | |
466 switch( adr->Opcode() ) { | |
467 | |
468 case Op_AddP: // No change to NULL-ness, so peek thru AddP's | |
469 adr = adr->in(AddPNode::Base); | |
470 continue; | |
471 | |
472 case Op_CastPP: | |
473 // If the CastPP is useless, just peek on through it. | |
474 if( ccp->type(adr) == ccp->type(adr->in(1)) ) { | |
475 // Remember the cast that we've peeked though. If we peek | |
476 // through more than one, then we end up remembering the highest | |
477 // one, that is, if in a loop, the one closest to the top. | |
478 skipped_cast = adr; | |
479 adr = adr->in(1); | |
480 continue; | |
481 } | |
482 // CastPP is going away in this pass! We need this memory op to be | |
483 // control-dependent on the test that is guarding the CastPP. | |
484 ccp->hash_delete(this); | |
485 set_req(MemNode::Control, adr->in(0)); | |
486 ccp->hash_insert(this); | |
487 return this; | |
488 | |
489 case Op_Phi: | |
490 // Attempt to float above a Phi to some dominating point. | |
491 if (adr->in(0) != NULL && adr->in(0)->is_CountedLoop()) { | |
492 // If we've already peeked through a Cast (which could have set the | |
493 // control), we can't float above a Phi, because the skipped Cast | |
494 // may not be loop invariant. | |
495 if (adr_phi_is_loop_invariant(adr, skipped_cast)) { | |
496 adr = adr->in(1); | |
497 continue; | |
498 } | |
499 } | |
500 | |
501 // Intentional fallthrough! | |
502 | |
503 // No obvious dominating point. The mem op is pinned below the Phi | |
504 // by the Phi itself. If the Phi goes away (no true value is merged) | |
505 // then the mem op can float, but not indefinitely. It must be pinned | |
506 // behind the controls leading to the Phi. | |
507 case Op_CheckCastPP: | |
508 // These usually stick around to change address type, however a | |
509 // useless one can be elided and we still need to pick up a control edge | |
510 if (adr->in(0) == NULL) { | |
511 // This CheckCastPP node has NO control and is likely useless. But we | |
512 // need check further up the ancestor chain for a control input to keep | |
513 // the node in place. 4959717. | |
514 skipped_cast = adr; | |
515 adr = adr->in(1); | |
516 continue; | |
517 } | |
518 ccp->hash_delete(this); | |
519 set_req(MemNode::Control, adr->in(0)); | |
520 ccp->hash_insert(this); | |
521 return this; | |
522 | |
523 // List of "safe" opcodes; those that implicitly block the memory | |
524 // op below any null check. | |
525 case Op_CastX2P: // no null checks on native pointers | |
526 case Op_Parm: // 'this' pointer is not null | |
527 case Op_LoadP: // Loading from within a klass | |
528 case Op_LoadKlass: // Loading from within a klass | |
529 case Op_ConP: // Loading from a klass | |
530 case Op_CreateEx: // Sucking up the guts of an exception oop | |
531 case Op_Con: // Reading from TLS | |
532 case Op_CMoveP: // CMoveP is pinned | |
533 break; // No progress | |
534 | |
535 case Op_Proj: // Direct call to an allocation routine | |
536 case Op_SCMemProj: // Memory state from store conditional ops | |
537 #ifdef ASSERT | |
538 { | |
539 assert(adr->as_Proj()->_con == TypeFunc::Parms, "must be return value"); | |
540 const Node* call = adr->in(0); | |
541 if (call->is_CallStaticJava()) { | |
542 const CallStaticJavaNode* call_java = call->as_CallStaticJava(); | |
543 assert(call_java && call_java->method() == NULL, "must be runtime call"); | |
544 // We further presume that this is one of | |
545 // new_instance_Java, new_array_Java, or | |
546 // the like, but do not assert for this. | |
547 } else if (call->is_Allocate()) { | |
548 // similar case to new_instance_Java, etc. | |
549 } else if (!call->is_CallLeaf()) { | |
550 // Projections from fetch_oop (OSR) are allowed as well. | |
551 ShouldNotReachHere(); | |
552 } | |
553 } | |
554 #endif | |
555 break; | |
556 default: | |
557 ShouldNotReachHere(); | |
558 } | |
559 break; | |
560 } | |
561 } | |
562 | |
563 return NULL; // No progress | |
564 } | |
565 | |
566 | |
567 //============================================================================= | |
568 uint LoadNode::size_of() const { return sizeof(*this); } | |
569 uint LoadNode::cmp( const Node &n ) const | |
570 { return !Type::cmp( _type, ((LoadNode&)n)._type ); } | |
571 const Type *LoadNode::bottom_type() const { return _type; } | |
572 uint LoadNode::ideal_reg() const { | |
573 return Matcher::base2reg[_type->base()]; | |
574 } | |
575 | |
576 #ifndef PRODUCT | |
577 void LoadNode::dump_spec(outputStream *st) const { | |
578 MemNode::dump_spec(st); | |
579 if( !Verbose && !WizardMode ) { | |
580 // standard dump does this in Verbose and WizardMode | |
581 st->print(" #"); _type->dump_on(st); | |
582 } | |
583 } | |
584 #endif | |
585 | |
586 | |
587 //----------------------------LoadNode::make----------------------------------- | |
588 // Polymorphic factory method: | |
589 LoadNode *LoadNode::make( Compile *C, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt ) { | |
590 // sanity check the alias category against the created node type | |
591 assert(!(adr_type->isa_oopptr() && | |
592 adr_type->offset() == oopDesc::klass_offset_in_bytes()), | |
593 "use LoadKlassNode instead"); | |
594 assert(!(adr_type->isa_aryptr() && | |
595 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()), | |
596 "use LoadRangeNode instead"); | |
597 switch (bt) { | |
598 case T_BOOLEAN: | |
599 case T_BYTE: return new (C, 3) LoadBNode(ctl, mem, adr, adr_type, rt->is_int() ); | |
600 case T_INT: return new (C, 3) LoadINode(ctl, mem, adr, adr_type, rt->is_int() ); | |
601 case T_CHAR: return new (C, 3) LoadCNode(ctl, mem, adr, adr_type, rt->is_int() ); | |
602 case T_SHORT: return new (C, 3) LoadSNode(ctl, mem, adr, adr_type, rt->is_int() ); | |
603 case T_LONG: return new (C, 3) LoadLNode(ctl, mem, adr, adr_type, rt->is_long() ); | |
604 case T_FLOAT: return new (C, 3) LoadFNode(ctl, mem, adr, adr_type, rt ); | |
605 case T_DOUBLE: return new (C, 3) LoadDNode(ctl, mem, adr, adr_type, rt ); | |
606 case T_ADDRESS: return new (C, 3) LoadPNode(ctl, mem, adr, adr_type, rt->is_ptr() ); | |
607 case T_OBJECT: return new (C, 3) LoadPNode(ctl, mem, adr, adr_type, rt->is_oopptr()); | |
608 } | |
609 ShouldNotReachHere(); | |
610 return (LoadNode*)NULL; | |
611 } | |
612 | |
613 LoadLNode* LoadLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt) { | |
614 bool require_atomic = true; | |
615 return new (C, 3) LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), require_atomic); | |
616 } | |
617 | |
618 | |
619 | |
620 | |
621 //------------------------------hash------------------------------------------- | |
622 uint LoadNode::hash() const { | |
623 // unroll addition of interesting fields | |
624 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address); | |
625 } | |
626 | |
627 //---------------------------can_see_stored_value------------------------------ | |
628 // This routine exists to make sure this set of tests is done the same | |
629 // everywhere. We need to make a coordinated change: first LoadNode::Ideal | |
630 // will change the graph shape in a way which makes memory alive twice at the | |
631 // same time (uses the Oracle model of aliasing), then some | |
632 // LoadXNode::Identity will fold things back to the equivalence-class model | |
633 // of aliasing. | |
634 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const { | |
635 Node* ld_adr = in(MemNode::Address); | |
636 | |
637 // Loop around twice in the case Load -> Initialize -> Store. | |
638 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.) | |
639 for (int trip = 0; trip <= 1; trip++) { | |
640 | |
641 if (st->is_Store()) { | |
642 Node* st_adr = st->in(MemNode::Address); | |
643 if (!phase->eqv(st_adr, ld_adr)) { | |
644 // Try harder before giving up... Match raw and non-raw pointers. | |
645 intptr_t st_off = 0; | |
646 AllocateNode* alloc = AllocateNode::Ideal_allocation(st_adr, phase, st_off); | |
647 if (alloc == NULL) return NULL; | |
648 intptr_t ld_off = 0; | |
649 AllocateNode* allo2 = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off); | |
650 if (alloc != allo2) return NULL; | |
651 if (ld_off != st_off) return NULL; | |
652 // At this point we have proven something like this setup: | |
653 // A = Allocate(...) | |
654 // L = LoadQ(, AddP(CastPP(, A.Parm),, #Off)) | |
655 // S = StoreQ(, AddP(, A.Parm , #Off), V) | |
656 // (Actually, we haven't yet proven the Q's are the same.) | |
657 // In other words, we are loading from a casted version of | |
658 // the same pointer-and-offset that we stored to. | |
659 // Thus, we are able to replace L by V. | |
660 } | |
661 // Now prove that we have a LoadQ matched to a StoreQ, for some Q. | |
662 if (store_Opcode() != st->Opcode()) | |
663 return NULL; | |
664 return st->in(MemNode::ValueIn); | |
665 } | |
666 | |
667 intptr_t offset = 0; // scratch | |
668 | |
669 // A load from a freshly-created object always returns zero. | |
670 // (This can happen after LoadNode::Ideal resets the load's memory input | |
671 // to find_captured_store, which returned InitializeNode::zero_memory.) | |
672 if (st->is_Proj() && st->in(0)->is_Allocate() && | |
673 st->in(0) == AllocateNode::Ideal_allocation(ld_adr, phase, offset) && | |
674 offset >= st->in(0)->as_Allocate()->minimum_header_size()) { | |
675 // return a zero value for the load's basic type | |
676 // (This is one of the few places where a generic PhaseTransform | |
677 // can create new nodes. Think of it as lazily manifesting | |
678 // virtually pre-existing constants.) | |
679 return phase->zerocon(memory_type()); | |
680 } | |
681 | |
682 // A load from an initialization barrier can match a captured store. | |
683 if (st->is_Proj() && st->in(0)->is_Initialize()) { | |
684 InitializeNode* init = st->in(0)->as_Initialize(); | |
685 AllocateNode* alloc = init->allocation(); | |
686 if (alloc != NULL && | |
687 alloc == AllocateNode::Ideal_allocation(ld_adr, phase, offset)) { | |
688 // examine a captured store value | |
689 st = init->find_captured_store(offset, memory_size(), phase); | |
690 if (st != NULL) | |
691 continue; // take one more trip around | |
692 } | |
693 } | |
694 | |
695 break; | |
696 } | |
697 | |
698 return NULL; | |
699 } | |
700 | |
701 //------------------------------Identity--------------------------------------- | |
702 // Loads are identity if previous store is to same address | |
703 Node *LoadNode::Identity( PhaseTransform *phase ) { | |
704 // If the previous store-maker is the right kind of Store, and the store is | |
705 // to the same address, then we are equal to the value stored. | |
706 Node* mem = in(MemNode::Memory); | |
707 Node* value = can_see_stored_value(mem, phase); | |
708 if( value ) { | |
709 // byte, short & char stores truncate naturally. | |
710 // A load has to load the truncated value which requires | |
711 // some sort of masking operation and that requires an | |
712 // Ideal call instead of an Identity call. | |
713 if (memory_size() < BytesPerInt) { | |
714 // If the input to the store does not fit with the load's result type, | |
715 // it must be truncated via an Ideal call. | |
716 if (!phase->type(value)->higher_equal(phase->type(this))) | |
717 return this; | |
718 } | |
719 // (This works even when value is a Con, but LoadNode::Value | |
720 // usually runs first, producing the singleton type of the Con.) | |
721 return value; | |
722 } | |
723 return this; | |
724 } | |
725 | |
726 //------------------------------Ideal------------------------------------------ | |
727 // If the load is from Field memory and the pointer is non-null, we can | |
728 // zero out the control input. | |
729 // If the offset is constant and the base is an object allocation, | |
730 // try to hook me up to the exact initializing store. | |
731 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) { | |
732 Node* p = MemNode::Ideal_common(phase, can_reshape); | |
733 if (p) return (p == NodeSentinel) ? NULL : p; | |
734 | |
735 Node* ctrl = in(MemNode::Control); | |
736 Node* address = in(MemNode::Address); | |
737 | |
738 // Skip up past a SafePoint control. Cannot do this for Stores because | |
739 // pointer stores & cardmarks must stay on the same side of a SafePoint. | |
740 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint && | |
741 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw ) { | |
742 ctrl = ctrl->in(0); | |
743 set_req(MemNode::Control,ctrl); | |
744 } | |
745 | |
746 // Check for useless control edge in some common special cases | |
747 if (in(MemNode::Control) != NULL) { | |
748 intptr_t ignore = 0; | |
749 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore); | |
750 if (base != NULL | |
751 && phase->type(base)->higher_equal(TypePtr::NOTNULL) | |
752 && detect_dominating_control(base->in(0), phase->C->start())) { | |
753 // A method-invariant, non-null address (constant or 'this' argument). | |
754 set_req(MemNode::Control, NULL); | |
755 } | |
756 } | |
757 | |
758 // Check for prior store with a different base or offset; make Load | |
759 // independent. Skip through any number of them. Bail out if the stores | |
760 // are in an endless dead cycle and report no progress. This is a key | |
761 // transform for Reflection. However, if after skipping through the Stores | |
762 // we can't then fold up against a prior store do NOT do the transform as | |
763 // this amounts to using the 'Oracle' model of aliasing. It leaves the same | |
764 // array memory alive twice: once for the hoisted Load and again after the | |
765 // bypassed Store. This situation only works if EVERYBODY who does | |
766 // anti-dependence work knows how to bypass. I.e. we need all | |
767 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is | |
768 // the alias index stuff. So instead, peek through Stores and IFF we can | |
769 // fold up, do so. | |
770 Node* prev_mem = find_previous_store(phase); | |
771 // Steps (a), (b): Walk past independent stores to find an exact match. | |
772 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) { | |
773 // (c) See if we can fold up on the spot, but don't fold up here. | |
774 // Fold-up might require truncation (for LoadB/LoadS/LoadC) or | |
775 // just return a prior value, which is done by Identity calls. | |
776 if (can_see_stored_value(prev_mem, phase)) { | |
777 // Make ready for step (d): | |
778 set_req(MemNode::Memory, prev_mem); | |
779 return this; | |
780 } | |
781 } | |
782 | |
783 return NULL; // No further progress | |
784 } | |
785 | |
786 // Helper to recognize certain Klass fields which are invariant across | |
787 // some group of array types (e.g., int[] or all T[] where T < Object). | |
788 const Type* | |
789 LoadNode::load_array_final_field(const TypeKlassPtr *tkls, | |
790 ciKlass* klass) const { | |
791 if (tkls->offset() == Klass::modifier_flags_offset_in_bytes() + (int)sizeof(oopDesc)) { | |
792 // The field is Klass::_modifier_flags. Return its (constant) value. | |
793 // (Folds up the 2nd indirection in aClassConstant.getModifiers().) | |
794 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags"); | |
795 return TypeInt::make(klass->modifier_flags()); | |
796 } | |
797 if (tkls->offset() == Klass::access_flags_offset_in_bytes() + (int)sizeof(oopDesc)) { | |
798 // The field is Klass::_access_flags. Return its (constant) value. | |
799 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).) | |
800 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags"); | |
801 return TypeInt::make(klass->access_flags()); | |
802 } | |
803 if (tkls->offset() == Klass::layout_helper_offset_in_bytes() + (int)sizeof(oopDesc)) { | |
804 // The field is Klass::_layout_helper. Return its constant value if known. | |
805 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper"); | |
806 return TypeInt::make(klass->layout_helper()); | |
807 } | |
808 | |
809 // No match. | |
810 return NULL; | |
811 } | |
812 | |
813 //------------------------------Value----------------------------------------- | |
814 const Type *LoadNode::Value( PhaseTransform *phase ) const { | |
815 // Either input is TOP ==> the result is TOP | |
816 Node* mem = in(MemNode::Memory); | |
817 const Type *t1 = phase->type(mem); | |
818 if (t1 == Type::TOP) return Type::TOP; | |
819 Node* adr = in(MemNode::Address); | |
820 const TypePtr* tp = phase->type(adr)->isa_ptr(); | |
821 if (tp == NULL || tp->empty()) return Type::TOP; | |
822 int off = tp->offset(); | |
823 assert(off != Type::OffsetTop, "case covered by TypePtr::empty"); | |
824 | |
825 // Try to guess loaded type from pointer type | |
826 if (tp->base() == Type::AryPtr) { | |
827 const Type *t = tp->is_aryptr()->elem(); | |
828 // Don't do this for integer types. There is only potential profit if | |
829 // the element type t is lower than _type; that is, for int types, if _type is | |
830 // more restrictive than t. This only happens here if one is short and the other | |
831 // char (both 16 bits), and in those cases we've made an intentional decision | |
832 // to use one kind of load over the other. See AndINode::Ideal and 4965907. | |
833 // Also, do not try to narrow the type for a LoadKlass, regardless of offset. | |
834 // | |
835 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8)) | |
836 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier | |
837 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been | |
838 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed, | |
839 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any. | |
840 // In fact, that could have been the original type of p1, and p1 could have | |
841 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the | |
842 // expression (LShiftL quux 3) independently optimized to the constant 8. | |
843 if ((t->isa_int() == NULL) && (t->isa_long() == NULL) | |
844 && Opcode() != Op_LoadKlass) { | |
845 // t might actually be lower than _type, if _type is a unique | |
846 // concrete subclass of abstract class t. | |
847 // Make sure the reference is not into the header, by comparing | |
848 // the offset against the offset of the start of the array's data. | |
849 // Different array types begin at slightly different offsets (12 vs. 16). | |
850 // We choose T_BYTE as an example base type that is least restrictive | |
851 // as to alignment, which will therefore produce the smallest | |
852 // possible base offset. | |
853 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE); | |
854 if ((uint)off >= (uint)min_base_off) { // is the offset beyond the header? | |
855 const Type* jt = t->join(_type); | |
856 // In any case, do not allow the join, per se, to empty out the type. | |
857 if (jt->empty() && !t->empty()) { | |
858 // This can happen if a interface-typed array narrows to a class type. | |
859 jt = _type; | |
860 } | |
861 return jt; | |
862 } | |
863 } | |
864 } else if (tp->base() == Type::InstPtr) { | |
865 assert( off != Type::OffsetBot || | |
866 // arrays can be cast to Objects | |
867 tp->is_oopptr()->klass()->is_java_lang_Object() || | |
868 // unsafe field access may not have a constant offset | |
869 phase->C->has_unsafe_access(), | |
870 "Field accesses must be precise" ); | |
871 // For oop loads, we expect the _type to be precise | |
872 } else if (tp->base() == Type::KlassPtr) { | |
873 assert( off != Type::OffsetBot || | |
874 // arrays can be cast to Objects | |
875 tp->is_klassptr()->klass()->is_java_lang_Object() || | |
876 // also allow array-loading from the primary supertype | |
877 // array during subtype checks | |
878 Opcode() == Op_LoadKlass, | |
879 "Field accesses must be precise" ); | |
880 // For klass/static loads, we expect the _type to be precise | |
881 } | |
882 | |
883 const TypeKlassPtr *tkls = tp->isa_klassptr(); | |
884 if (tkls != NULL && !StressReflectiveCode) { | |
885 ciKlass* klass = tkls->klass(); | |
886 if (klass->is_loaded() && tkls->klass_is_exact()) { | |
887 // We are loading a field from a Klass metaobject whose identity | |
888 // is known at compile time (the type is "exact" or "precise"). | |
889 // Check for fields we know are maintained as constants by the VM. | |
890 if (tkls->offset() == Klass::super_check_offset_offset_in_bytes() + (int)sizeof(oopDesc)) { | |
891 // The field is Klass::_super_check_offset. Return its (constant) value. | |
892 // (Folds up type checking code.) | |
893 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset"); | |
894 return TypeInt::make(klass->super_check_offset()); | |
895 } | |
896 // Compute index into primary_supers array | |
897 juint depth = (tkls->offset() - (Klass::primary_supers_offset_in_bytes() + (int)sizeof(oopDesc))) / sizeof(klassOop); | |
898 // Check for overflowing; use unsigned compare to handle the negative case. | |
899 if( depth < ciKlass::primary_super_limit() ) { | |
900 // The field is an element of Klass::_primary_supers. Return its (constant) value. | |
901 // (Folds up type checking code.) | |
902 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers"); | |
903 ciKlass *ss = klass->super_of_depth(depth); | |
904 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR; | |
905 } | |
906 const Type* aift = load_array_final_field(tkls, klass); | |
907 if (aift != NULL) return aift; | |
908 if (tkls->offset() == in_bytes(arrayKlass::component_mirror_offset()) + (int)sizeof(oopDesc) | |
909 && klass->is_array_klass()) { | |
910 // The field is arrayKlass::_component_mirror. Return its (constant) value. | |
911 // (Folds up aClassConstant.getComponentType, common in Arrays.copyOf.) | |
912 assert(Opcode() == Op_LoadP, "must load an oop from _component_mirror"); | |
913 return TypeInstPtr::make(klass->as_array_klass()->component_mirror()); | |
914 } | |
915 if (tkls->offset() == Klass::java_mirror_offset_in_bytes() + (int)sizeof(oopDesc)) { | |
916 // The field is Klass::_java_mirror. Return its (constant) value. | |
917 // (Folds up the 2nd indirection in anObjConstant.getClass().) | |
918 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror"); | |
919 return TypeInstPtr::make(klass->java_mirror()); | |
920 } | |
921 } | |
922 | |
923 // We can still check if we are loading from the primary_supers array at a | |
924 // shallow enough depth. Even though the klass is not exact, entries less | |
925 // than or equal to its super depth are correct. | |
926 if (klass->is_loaded() ) { | |
927 ciType *inner = klass->klass(); | |
928 while( inner->is_obj_array_klass() ) | |
929 inner = inner->as_obj_array_klass()->base_element_type(); | |
930 if( inner->is_instance_klass() && | |
931 !inner->as_instance_klass()->flags().is_interface() ) { | |
932 // Compute index into primary_supers array | |
933 juint depth = (tkls->offset() - (Klass::primary_supers_offset_in_bytes() + (int)sizeof(oopDesc))) / sizeof(klassOop); | |
934 // Check for overflowing; use unsigned compare to handle the negative case. | |
935 if( depth < ciKlass::primary_super_limit() && | |
936 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case | |
937 // The field is an element of Klass::_primary_supers. Return its (constant) value. | |
938 // (Folds up type checking code.) | |
939 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers"); | |
940 ciKlass *ss = klass->super_of_depth(depth); | |
941 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR; | |
942 } | |
943 } | |
944 } | |
945 | |
946 // If the type is enough to determine that the thing is not an array, | |
947 // we can give the layout_helper a positive interval type. | |
948 // This will help short-circuit some reflective code. | |
949 if (tkls->offset() == Klass::layout_helper_offset_in_bytes() + (int)sizeof(oopDesc) | |
950 && !klass->is_array_klass() // not directly typed as an array | |
951 && !klass->is_interface() // specifically not Serializable & Cloneable | |
952 && !klass->is_java_lang_Object() // not the supertype of all T[] | |
953 ) { | |
954 // Note: When interfaces are reliable, we can narrow the interface | |
955 // test to (klass != Serializable && klass != Cloneable). | |
956 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper"); | |
957 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false); | |
958 // The key property of this type is that it folds up tests | |
959 // for array-ness, since it proves that the layout_helper is positive. | |
960 // Thus, a generic value like the basic object layout helper works fine. | |
961 return TypeInt::make(min_size, max_jint, Type::WidenMin); | |
962 } | |
963 } | |
964 | |
965 // If we are loading from a freshly-allocated object, produce a zero, | |
966 // if the load is provably beyond the header of the object. | |
967 // (Also allow a variable load from a fresh array to produce zero.) | |
968 if (ReduceFieldZeroing) { | |
969 Node* value = can_see_stored_value(mem,phase); | |
970 if (value != NULL && value->is_Con()) | |
971 return value->bottom_type(); | |
972 } | |
973 | |
974 return _type; | |
975 } | |
976 | |
977 //------------------------------match_edge------------------------------------- | |
978 // Do we Match on this edge index or not? Match only the address. | |
979 uint LoadNode::match_edge(uint idx) const { | |
980 return idx == MemNode::Address; | |
981 } | |
982 | |
983 //--------------------------LoadBNode::Ideal-------------------------------------- | |
984 // | |
985 // If the previous store is to the same address as this load, | |
986 // and the value stored was larger than a byte, replace this load | |
987 // with the value stored truncated to a byte. If no truncation is | |
988 // needed, the replacement is done in LoadNode::Identity(). | |
989 // | |
990 Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) { | |
991 Node* mem = in(MemNode::Memory); | |
992 Node* value = can_see_stored_value(mem,phase); | |
993 if( value && !phase->type(value)->higher_equal( _type ) ) { | |
994 Node *result = phase->transform( new (phase->C, 3) LShiftINode(value, phase->intcon(24)) ); | |
995 return new (phase->C, 3) RShiftINode(result, phase->intcon(24)); | |
996 } | |
997 // Identity call will handle the case where truncation is not needed. | |
998 return LoadNode::Ideal(phase, can_reshape); | |
999 } | |
1000 | |
1001 //--------------------------LoadCNode::Ideal-------------------------------------- | |
1002 // | |
1003 // If the previous store is to the same address as this load, | |
1004 // and the value stored was larger than a char, replace this load | |
1005 // with the value stored truncated to a char. If no truncation is | |
1006 // needed, the replacement is done in LoadNode::Identity(). | |
1007 // | |
1008 Node *LoadCNode::Ideal(PhaseGVN *phase, bool can_reshape) { | |
1009 Node* mem = in(MemNode::Memory); | |
1010 Node* value = can_see_stored_value(mem,phase); | |
1011 if( value && !phase->type(value)->higher_equal( _type ) ) | |
1012 return new (phase->C, 3) AndINode(value,phase->intcon(0xFFFF)); | |
1013 // Identity call will handle the case where truncation is not needed. | |
1014 return LoadNode::Ideal(phase, can_reshape); | |
1015 } | |
1016 | |
1017 //--------------------------LoadSNode::Ideal-------------------------------------- | |
1018 // | |
1019 // If the previous store is to the same address as this load, | |
1020 // and the value stored was larger than a short, replace this load | |
1021 // with the value stored truncated to a short. If no truncation is | |
1022 // needed, the replacement is done in LoadNode::Identity(). | |
1023 // | |
1024 Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) { | |
1025 Node* mem = in(MemNode::Memory); | |
1026 Node* value = can_see_stored_value(mem,phase); | |
1027 if( value && !phase->type(value)->higher_equal( _type ) ) { | |
1028 Node *result = phase->transform( new (phase->C, 3) LShiftINode(value, phase->intcon(16)) ); | |
1029 return new (phase->C, 3) RShiftINode(result, phase->intcon(16)); | |
1030 } | |
1031 // Identity call will handle the case where truncation is not needed. | |
1032 return LoadNode::Ideal(phase, can_reshape); | |
1033 } | |
1034 | |
1035 //============================================================================= | |
1036 //------------------------------Value------------------------------------------ | |
1037 const Type *LoadKlassNode::Value( PhaseTransform *phase ) const { | |
1038 // Either input is TOP ==> the result is TOP | |
1039 const Type *t1 = phase->type( in(MemNode::Memory) ); | |
1040 if (t1 == Type::TOP) return Type::TOP; | |
1041 Node *adr = in(MemNode::Address); | |
1042 const Type *t2 = phase->type( adr ); | |
1043 if (t2 == Type::TOP) return Type::TOP; | |
1044 const TypePtr *tp = t2->is_ptr(); | |
1045 if (TypePtr::above_centerline(tp->ptr()) || | |
1046 tp->ptr() == TypePtr::Null) return Type::TOP; | |
1047 | |
1048 // Return a more precise klass, if possible | |
1049 const TypeInstPtr *tinst = tp->isa_instptr(); | |
1050 if (tinst != NULL) { | |
1051 ciInstanceKlass* ik = tinst->klass()->as_instance_klass(); | |
1052 int offset = tinst->offset(); | |
1053 if (ik == phase->C->env()->Class_klass() | |
1054 && (offset == java_lang_Class::klass_offset_in_bytes() || | |
1055 offset == java_lang_Class::array_klass_offset_in_bytes())) { | |
1056 // We are loading a special hidden field from a Class mirror object, | |
1057 // the field which points to the VM's Klass metaobject. | |
1058 ciType* t = tinst->java_mirror_type(); | |
1059 // java_mirror_type returns non-null for compile-time Class constants. | |
1060 if (t != NULL) { | |
1061 // constant oop => constant klass | |
1062 if (offset == java_lang_Class::array_klass_offset_in_bytes()) { | |
1063 return TypeKlassPtr::make(ciArrayKlass::make(t)); | |
1064 } | |
1065 if (!t->is_klass()) { | |
1066 // a primitive Class (e.g., int.class) has NULL for a klass field | |
1067 return TypePtr::NULL_PTR; | |
1068 } | |
1069 // (Folds up the 1st indirection in aClassConstant.getModifiers().) | |
1070 return TypeKlassPtr::make(t->as_klass()); | |
1071 } | |
1072 // non-constant mirror, so we can't tell what's going on | |
1073 } | |
1074 if( !ik->is_loaded() ) | |
1075 return _type; // Bail out if not loaded | |
1076 if (offset == oopDesc::klass_offset_in_bytes()) { | |
1077 if (tinst->klass_is_exact()) { | |
1078 return TypeKlassPtr::make(ik); | |
1079 } | |
1080 // See if we can become precise: no subklasses and no interface | |
1081 // (Note: We need to support verified interfaces.) | |
1082 if (!ik->is_interface() && !ik->has_subklass()) { | |
1083 //assert(!UseExactTypes, "this code should be useless with exact types"); | |
1084 // Add a dependence; if any subclass added we need to recompile | |
1085 if (!ik->is_final()) { | |
1086 // %%% should use stronger assert_unique_concrete_subtype instead | |
1087 phase->C->dependencies()->assert_leaf_type(ik); | |
1088 } | |
1089 // Return precise klass | |
1090 return TypeKlassPtr::make(ik); | |
1091 } | |
1092 | |
1093 // Return root of possible klass | |
1094 return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/); | |
1095 } | |
1096 } | |
1097 | |
1098 // Check for loading klass from an array | |
1099 const TypeAryPtr *tary = tp->isa_aryptr(); | |
1100 if( tary != NULL ) { | |
1101 ciKlass *tary_klass = tary->klass(); | |
1102 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP | |
1103 && tary->offset() == oopDesc::klass_offset_in_bytes()) { | |
1104 if (tary->klass_is_exact()) { | |
1105 return TypeKlassPtr::make(tary_klass); | |
1106 } | |
1107 ciArrayKlass *ak = tary->klass()->as_array_klass(); | |
1108 // If the klass is an object array, we defer the question to the | |
1109 // array component klass. | |
1110 if( ak->is_obj_array_klass() ) { | |
1111 assert( ak->is_loaded(), "" ); | |
1112 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass(); | |
1113 if( base_k->is_loaded() && base_k->is_instance_klass() ) { | |
1114 ciInstanceKlass* ik = base_k->as_instance_klass(); | |
1115 // See if we can become precise: no subklasses and no interface | |
1116 if (!ik->is_interface() && !ik->has_subklass()) { | |
1117 //assert(!UseExactTypes, "this code should be useless with exact types"); | |
1118 // Add a dependence; if any subclass added we need to recompile | |
1119 if (!ik->is_final()) { | |
1120 phase->C->dependencies()->assert_leaf_type(ik); | |
1121 } | |
1122 // Return precise array klass | |
1123 return TypeKlassPtr::make(ak); | |
1124 } | |
1125 } | |
1126 return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/); | |
1127 } else { // Found a type-array? | |
1128 //assert(!UseExactTypes, "this code should be useless with exact types"); | |
1129 assert( ak->is_type_array_klass(), "" ); | |
1130 return TypeKlassPtr::make(ak); // These are always precise | |
1131 } | |
1132 } | |
1133 } | |
1134 | |
1135 // Check for loading klass from an array klass | |
1136 const TypeKlassPtr *tkls = tp->isa_klassptr(); | |
1137 if (tkls != NULL && !StressReflectiveCode) { | |
1138 ciKlass* klass = tkls->klass(); | |
1139 if( !klass->is_loaded() ) | |
1140 return _type; // Bail out if not loaded | |
1141 if( klass->is_obj_array_klass() && | |
1142 (uint)tkls->offset() == objArrayKlass::element_klass_offset_in_bytes() + sizeof(oopDesc)) { | |
1143 ciKlass* elem = klass->as_obj_array_klass()->element_klass(); | |
1144 // // Always returning precise element type is incorrect, | |
1145 // // e.g., element type could be object and array may contain strings | |
1146 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0); | |
1147 | |
1148 // The array's TypeKlassPtr was declared 'precise' or 'not precise' | |
1149 // according to the element type's subclassing. | |
1150 return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/); | |
1151 } | |
1152 if( klass->is_instance_klass() && tkls->klass_is_exact() && | |
1153 (uint)tkls->offset() == Klass::super_offset_in_bytes() + sizeof(oopDesc)) { | |
1154 ciKlass* sup = klass->as_instance_klass()->super(); | |
1155 // The field is Klass::_super. Return its (constant) value. | |
1156 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().) | |
1157 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR; | |
1158 } | |
1159 } | |
1160 | |
1161 // Bailout case | |
1162 return LoadNode::Value(phase); | |
1163 } | |
1164 | |
1165 //------------------------------Identity--------------------------------------- | |
1166 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k. | |
1167 // Also feed through the klass in Allocate(...klass...)._klass. | |
1168 Node* LoadKlassNode::Identity( PhaseTransform *phase ) { | |
1169 Node* x = LoadNode::Identity(phase); | |
1170 if (x != this) return x; | |
1171 | |
1172 // Take apart the address into an oop and and offset. | |
1173 // Return 'this' if we cannot. | |
1174 Node* adr = in(MemNode::Address); | |
1175 intptr_t offset = 0; | |
1176 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); | |
1177 if (base == NULL) return this; | |
1178 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr(); | |
1179 if (toop == NULL) return this; | |
1180 | |
1181 // We can fetch the klass directly through an AllocateNode. | |
1182 // This works even if the klass is not constant (clone or newArray). | |
1183 if (offset == oopDesc::klass_offset_in_bytes()) { | |
1184 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase); | |
1185 if (allocated_klass != NULL) { | |
1186 return allocated_klass; | |
1187 } | |
1188 } | |
1189 | |
1190 // Simplify k.java_mirror.as_klass to plain k, where k is a klassOop. | |
1191 // Simplify ak.component_mirror.array_klass to plain ak, ak an arrayKlass. | |
1192 // See inline_native_Class_query for occurrences of these patterns. | |
1193 // Java Example: x.getClass().isAssignableFrom(y) | |
1194 // Java Example: Array.newInstance(x.getClass().getComponentType(), n) | |
1195 // | |
1196 // This improves reflective code, often making the Class | |
1197 // mirror go completely dead. (Current exception: Class | |
1198 // mirrors may appear in debug info, but we could clean them out by | |
1199 // introducing a new debug info operator for klassOop.java_mirror). | |
1200 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass() | |
1201 && (offset == java_lang_Class::klass_offset_in_bytes() || | |
1202 offset == java_lang_Class::array_klass_offset_in_bytes())) { | |
1203 // We are loading a special hidden field from a Class mirror, | |
1204 // the field which points to its Klass or arrayKlass metaobject. | |
1205 if (base->is_Load()) { | |
1206 Node* adr2 = base->in(MemNode::Address); | |
1207 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr(); | |
1208 if (tkls != NULL && !tkls->empty() | |
1209 && (tkls->klass()->is_instance_klass() || | |
1210 tkls->klass()->is_array_klass()) | |
1211 && adr2->is_AddP() | |
1212 ) { | |
1213 int mirror_field = Klass::java_mirror_offset_in_bytes(); | |
1214 if (offset == java_lang_Class::array_klass_offset_in_bytes()) { | |
1215 mirror_field = in_bytes(arrayKlass::component_mirror_offset()); | |
1216 } | |
1217 if (tkls->offset() == mirror_field + (int)sizeof(oopDesc)) { | |
1218 return adr2->in(AddPNode::Base); | |
1219 } | |
1220 } | |
1221 } | |
1222 } | |
1223 | |
1224 return this; | |
1225 } | |
1226 | |
1227 //------------------------------Value----------------------------------------- | |
1228 const Type *LoadRangeNode::Value( PhaseTransform *phase ) const { | |
1229 // Either input is TOP ==> the result is TOP | |
1230 const Type *t1 = phase->type( in(MemNode::Memory) ); | |
1231 if( t1 == Type::TOP ) return Type::TOP; | |
1232 Node *adr = in(MemNode::Address); | |
1233 const Type *t2 = phase->type( adr ); | |
1234 if( t2 == Type::TOP ) return Type::TOP; | |
1235 const TypePtr *tp = t2->is_ptr(); | |
1236 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP; | |
1237 const TypeAryPtr *tap = tp->isa_aryptr(); | |
1238 if( !tap ) return _type; | |
1239 return tap->size(); | |
1240 } | |
1241 | |
1242 //------------------------------Identity--------------------------------------- | |
1243 // Feed through the length in AllocateArray(...length...)._length. | |
1244 Node* LoadRangeNode::Identity( PhaseTransform *phase ) { | |
1245 Node* x = LoadINode::Identity(phase); | |
1246 if (x != this) return x; | |
1247 | |
1248 // Take apart the address into an oop and and offset. | |
1249 // Return 'this' if we cannot. | |
1250 Node* adr = in(MemNode::Address); | |
1251 intptr_t offset = 0; | |
1252 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); | |
1253 if (base == NULL) return this; | |
1254 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr(); | |
1255 if (tary == NULL) return this; | |
1256 | |
1257 // We can fetch the length directly through an AllocateArrayNode. | |
1258 // This works even if the length is not constant (clone or newArray). | |
1259 if (offset == arrayOopDesc::length_offset_in_bytes()) { | |
1260 Node* allocated_length = AllocateArrayNode::Ideal_length(base, phase); | |
1261 if (allocated_length != NULL) { | |
1262 return allocated_length; | |
1263 } | |
1264 } | |
1265 | |
1266 return this; | |
1267 | |
1268 } | |
1269 //============================================================================= | |
1270 //---------------------------StoreNode::make----------------------------------- | |
1271 // Polymorphic factory method: | |
1272 StoreNode* StoreNode::make( Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt ) { | |
1273 switch (bt) { | |
1274 case T_BOOLEAN: | |
1275 case T_BYTE: return new (C, 4) StoreBNode(ctl, mem, adr, adr_type, val); | |
1276 case T_INT: return new (C, 4) StoreINode(ctl, mem, adr, adr_type, val); | |
1277 case T_CHAR: | |
1278 case T_SHORT: return new (C, 4) StoreCNode(ctl, mem, adr, adr_type, val); | |
1279 case T_LONG: return new (C, 4) StoreLNode(ctl, mem, adr, adr_type, val); | |
1280 case T_FLOAT: return new (C, 4) StoreFNode(ctl, mem, adr, adr_type, val); | |
1281 case T_DOUBLE: return new (C, 4) StoreDNode(ctl, mem, adr, adr_type, val); | |
1282 case T_ADDRESS: | |
1283 case T_OBJECT: return new (C, 4) StorePNode(ctl, mem, adr, adr_type, val); | |
1284 } | |
1285 ShouldNotReachHere(); | |
1286 return (StoreNode*)NULL; | |
1287 } | |
1288 | |
1289 StoreLNode* StoreLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val) { | |
1290 bool require_atomic = true; | |
1291 return new (C, 4) StoreLNode(ctl, mem, adr, adr_type, val, require_atomic); | |
1292 } | |
1293 | |
1294 | |
1295 //--------------------------bottom_type---------------------------------------- | |
1296 const Type *StoreNode::bottom_type() const { | |
1297 return Type::MEMORY; | |
1298 } | |
1299 | |
1300 //------------------------------hash------------------------------------------- | |
1301 uint StoreNode::hash() const { | |
1302 // unroll addition of interesting fields | |
1303 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn); | |
1304 | |
1305 // Since they are not commoned, do not hash them: | |
1306 return NO_HASH; | |
1307 } | |
1308 | |
1309 //------------------------------Ideal------------------------------------------ | |
1310 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x). | |
1311 // When a store immediately follows a relevant allocation/initialization, | |
1312 // try to capture it into the initialization, or hoist it above. | |
1313 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) { | |
1314 Node* p = MemNode::Ideal_common(phase, can_reshape); | |
1315 if (p) return (p == NodeSentinel) ? NULL : p; | |
1316 | |
1317 Node* mem = in(MemNode::Memory); | |
1318 Node* address = in(MemNode::Address); | |
1319 | |
1320 // Back-to-back stores to same address? Fold em up. | |
1321 // Generally unsafe if I have intervening uses... | |
1322 if (mem->is_Store() && phase->eqv_uncast(mem->in(MemNode::Address), address)) { | |
1323 // Looking at a dead closed cycle of memory? | |
1324 assert(mem != mem->in(MemNode::Memory), "dead loop in StoreNode::Ideal"); | |
1325 | |
1326 assert(Opcode() == mem->Opcode() || | |
1327 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw, | |
1328 "no mismatched stores, except on raw memory"); | |
1329 | |
1330 if (mem->outcnt() == 1 && // check for intervening uses | |
1331 mem->as_Store()->memory_size() <= this->memory_size()) { | |
1332 // If anybody other than 'this' uses 'mem', we cannot fold 'mem' away. | |
1333 // For example, 'mem' might be the final state at a conditional return. | |
1334 // Or, 'mem' might be used by some node which is live at the same time | |
1335 // 'this' is live, which might be unschedulable. So, require exactly | |
1336 // ONE user, the 'this' store, until such time as we clone 'mem' for | |
1337 // each of 'mem's uses (thus making the exactly-1-user-rule hold true). | |
1338 if (can_reshape) { // (%%% is this an anachronism?) | |
1339 set_req_X(MemNode::Memory, mem->in(MemNode::Memory), | |
1340 phase->is_IterGVN()); | |
1341 } else { | |
1342 // It's OK to do this in the parser, since DU info is always accurate, | |
1343 // and the parser always refers to nodes via SafePointNode maps. | |
1344 set_req(MemNode::Memory, mem->in(MemNode::Memory)); | |
1345 } | |
1346 return this; | |
1347 } | |
1348 } | |
1349 | |
1350 // Capture an unaliased, unconditional, simple store into an initializer. | |
1351 // Or, if it is independent of the allocation, hoist it above the allocation. | |
1352 if (ReduceFieldZeroing && /*can_reshape &&*/ | |
1353 mem->is_Proj() && mem->in(0)->is_Initialize()) { | |
1354 InitializeNode* init = mem->in(0)->as_Initialize(); | |
1355 intptr_t offset = init->can_capture_store(this, phase); | |
1356 if (offset > 0) { | |
1357 Node* moved = init->capture_store(this, offset, phase); | |
1358 // If the InitializeNode captured me, it made a raw copy of me, | |
1359 // and I need to disappear. | |
1360 if (moved != NULL) { | |
1361 // %%% hack to ensure that Ideal returns a new node: | |
1362 mem = MergeMemNode::make(phase->C, mem); | |
1363 return mem; // fold me away | |
1364 } | |
1365 } | |
1366 } | |
1367 | |
1368 return NULL; // No further progress | |
1369 } | |
1370 | |
1371 //------------------------------Value----------------------------------------- | |
1372 const Type *StoreNode::Value( PhaseTransform *phase ) const { | |
1373 // Either input is TOP ==> the result is TOP | |
1374 const Type *t1 = phase->type( in(MemNode::Memory) ); | |
1375 if( t1 == Type::TOP ) return Type::TOP; | |
1376 const Type *t2 = phase->type( in(MemNode::Address) ); | |
1377 if( t2 == Type::TOP ) return Type::TOP; | |
1378 const Type *t3 = phase->type( in(MemNode::ValueIn) ); | |
1379 if( t3 == Type::TOP ) return Type::TOP; | |
1380 return Type::MEMORY; | |
1381 } | |
1382 | |
1383 //------------------------------Identity--------------------------------------- | |
1384 // Remove redundant stores: | |
1385 // Store(m, p, Load(m, p)) changes to m. | |
1386 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x). | |
1387 Node *StoreNode::Identity( PhaseTransform *phase ) { | |
1388 Node* mem = in(MemNode::Memory); | |
1389 Node* adr = in(MemNode::Address); | |
1390 Node* val = in(MemNode::ValueIn); | |
1391 | |
1392 // Load then Store? Then the Store is useless | |
1393 if (val->is_Load() && | |
1394 phase->eqv_uncast( val->in(MemNode::Address), adr ) && | |
1395 phase->eqv_uncast( val->in(MemNode::Memory ), mem ) && | |
1396 val->as_Load()->store_Opcode() == Opcode()) { | |
1397 return mem; | |
1398 } | |
1399 | |
1400 // Two stores in a row of the same value? | |
1401 if (mem->is_Store() && | |
1402 phase->eqv_uncast( mem->in(MemNode::Address), adr ) && | |
1403 phase->eqv_uncast( mem->in(MemNode::ValueIn), val ) && | |
1404 mem->Opcode() == Opcode()) { | |
1405 return mem; | |
1406 } | |
1407 | |
1408 // Store of zero anywhere into a freshly-allocated object? | |
1409 // Then the store is useless. | |
1410 // (It must already have been captured by the InitializeNode.) | |
1411 if (ReduceFieldZeroing && phase->type(val)->is_zero_type()) { | |
1412 // a newly allocated object is already all-zeroes everywhere | |
1413 if (mem->is_Proj() && mem->in(0)->is_Allocate()) { | |
1414 return mem; | |
1415 } | |
1416 | |
1417 // the store may also apply to zero-bits in an earlier object | |
1418 Node* prev_mem = find_previous_store(phase); | |
1419 // Steps (a), (b): Walk past independent stores to find an exact match. | |
1420 if (prev_mem != NULL) { | |
1421 Node* prev_val = can_see_stored_value(prev_mem, phase); | |
1422 if (prev_val != NULL && phase->eqv(prev_val, val)) { | |
1423 // prev_val and val might differ by a cast; it would be good | |
1424 // to keep the more informative of the two. | |
1425 return mem; | |
1426 } | |
1427 } | |
1428 } | |
1429 | |
1430 return this; | |
1431 } | |
1432 | |
1433 //------------------------------match_edge------------------------------------- | |
1434 // Do we Match on this edge index or not? Match only memory & value | |
1435 uint StoreNode::match_edge(uint idx) const { | |
1436 return idx == MemNode::Address || idx == MemNode::ValueIn; | |
1437 } | |
1438 | |
1439 //------------------------------cmp-------------------------------------------- | |
1440 // Do not common stores up together. They generally have to be split | |
1441 // back up anyways, so do not bother. | |
1442 uint StoreNode::cmp( const Node &n ) const { | |
1443 return (&n == this); // Always fail except on self | |
1444 } | |
1445 | |
1446 //------------------------------Ideal_masked_input----------------------------- | |
1447 // Check for a useless mask before a partial-word store | |
1448 // (StoreB ... (AndI valIn conIa) ) | |
1449 // If (conIa & mask == mask) this simplifies to | |
1450 // (StoreB ... (valIn) ) | |
1451 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) { | |
1452 Node *val = in(MemNode::ValueIn); | |
1453 if( val->Opcode() == Op_AndI ) { | |
1454 const TypeInt *t = phase->type( val->in(2) )->isa_int(); | |
1455 if( t && t->is_con() && (t->get_con() & mask) == mask ) { | |
1456 set_req(MemNode::ValueIn, val->in(1)); | |
1457 return this; | |
1458 } | |
1459 } | |
1460 return NULL; | |
1461 } | |
1462 | |
1463 | |
1464 //------------------------------Ideal_sign_extended_input---------------------- | |
1465 // Check for useless sign-extension before a partial-word store | |
1466 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) ) | |
1467 // If (conIL == conIR && conIR <= num_bits) this simplifies to | |
1468 // (StoreB ... (valIn) ) | |
1469 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) { | |
1470 Node *val = in(MemNode::ValueIn); | |
1471 if( val->Opcode() == Op_RShiftI ) { | |
1472 const TypeInt *t = phase->type( val->in(2) )->isa_int(); | |
1473 if( t && t->is_con() && (t->get_con() <= num_bits) ) { | |
1474 Node *shl = val->in(1); | |
1475 if( shl->Opcode() == Op_LShiftI ) { | |
1476 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int(); | |
1477 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) { | |
1478 set_req(MemNode::ValueIn, shl->in(1)); | |
1479 return this; | |
1480 } | |
1481 } | |
1482 } | |
1483 } | |
1484 return NULL; | |
1485 } | |
1486 | |
1487 //------------------------------value_never_loaded----------------------------------- | |
1488 // Determine whether there are any possible loads of the value stored. | |
1489 // For simplicity, we actually check if there are any loads from the | |
1490 // address stored to, not just for loads of the value stored by this node. | |
1491 // | |
1492 bool StoreNode::value_never_loaded( PhaseTransform *phase) const { | |
1493 Node *adr = in(Address); | |
1494 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr(); | |
1495 if (adr_oop == NULL) | |
1496 return false; | |
1497 if (!adr_oop->is_instance()) | |
1498 return false; // if not a distinct instance, there may be aliases of the address | |
1499 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) { | |
1500 Node *use = adr->fast_out(i); | |
1501 int opc = use->Opcode(); | |
1502 if (use->is_Load() || use->is_LoadStore()) { | |
1503 return false; | |
1504 } | |
1505 } | |
1506 return true; | |
1507 } | |
1508 | |
1509 //============================================================================= | |
1510 //------------------------------Ideal------------------------------------------ | |
1511 // If the store is from an AND mask that leaves the low bits untouched, then | |
1512 // we can skip the AND operation. If the store is from a sign-extension | |
1513 // (a left shift, then right shift) we can skip both. | |
1514 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){ | |
1515 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF); | |
1516 if( progress != NULL ) return progress; | |
1517 | |
1518 progress = StoreNode::Ideal_sign_extended_input(phase, 24); | |
1519 if( progress != NULL ) return progress; | |
1520 | |
1521 // Finally check the default case | |
1522 return StoreNode::Ideal(phase, can_reshape); | |
1523 } | |
1524 | |
1525 //============================================================================= | |
1526 //------------------------------Ideal------------------------------------------ | |
1527 // If the store is from an AND mask that leaves the low bits untouched, then | |
1528 // we can skip the AND operation | |
1529 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){ | |
1530 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF); | |
1531 if( progress != NULL ) return progress; | |
1532 | |
1533 progress = StoreNode::Ideal_sign_extended_input(phase, 16); | |
1534 if( progress != NULL ) return progress; | |
1535 | |
1536 // Finally check the default case | |
1537 return StoreNode::Ideal(phase, can_reshape); | |
1538 } | |
1539 | |
1540 //============================================================================= | |
1541 //------------------------------Identity--------------------------------------- | |
1542 Node *StoreCMNode::Identity( PhaseTransform *phase ) { | |
1543 // No need to card mark when storing a null ptr | |
1544 Node* my_store = in(MemNode::OopStore); | |
1545 if (my_store->is_Store()) { | |
1546 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) ); | |
1547 if( t1 == TypePtr::NULL_PTR ) { | |
1548 return in(MemNode::Memory); | |
1549 } | |
1550 } | |
1551 return this; | |
1552 } | |
1553 | |
1554 //------------------------------Value----------------------------------------- | |
1555 const Type *StoreCMNode::Value( PhaseTransform *phase ) const { | |
1556 // If extra input is TOP ==> the result is TOP | |
1557 const Type *t1 = phase->type( in(MemNode::OopStore) ); | |
1558 if( t1 == Type::TOP ) return Type::TOP; | |
1559 | |
1560 return StoreNode::Value( phase ); | |
1561 } | |
1562 | |
1563 | |
1564 //============================================================================= | |
1565 //----------------------------------SCMemProjNode------------------------------ | |
1566 const Type * SCMemProjNode::Value( PhaseTransform *phase ) const | |
1567 { | |
1568 return bottom_type(); | |
1569 } | |
1570 | |
1571 //============================================================================= | |
1572 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : Node(5) { | |
1573 init_req(MemNode::Control, c ); | |
1574 init_req(MemNode::Memory , mem); | |
1575 init_req(MemNode::Address, adr); | |
1576 init_req(MemNode::ValueIn, val); | |
1577 init_req( ExpectedIn, ex ); | |
1578 init_class_id(Class_LoadStore); | |
1579 | |
1580 } | |
1581 | |
1582 //============================================================================= | |
1583 //-------------------------------adr_type-------------------------------------- | |
1584 // Do we Match on this edge index or not? Do not match memory | |
1585 const TypePtr* ClearArrayNode::adr_type() const { | |
1586 Node *adr = in(3); | |
1587 return MemNode::calculate_adr_type(adr->bottom_type()); | |
1588 } | |
1589 | |
1590 //------------------------------match_edge------------------------------------- | |
1591 // Do we Match on this edge index or not? Do not match memory | |
1592 uint ClearArrayNode::match_edge(uint idx) const { | |
1593 return idx > 1; | |
1594 } | |
1595 | |
1596 //------------------------------Identity--------------------------------------- | |
1597 // Clearing a zero length array does nothing | |
1598 Node *ClearArrayNode::Identity( PhaseTransform *phase ) { | |
1599 return phase->type(in(2))->higher_equal(TypeInt::ZERO) ? in(1) : this; | |
1600 } | |
1601 | |
1602 //------------------------------Idealize--------------------------------------- | |
1603 // Clearing a short array is faster with stores | |
1604 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape){ | |
1605 const int unit = BytesPerLong; | |
1606 const TypeX* t = phase->type(in(2))->isa_intptr_t(); | |
1607 if (!t) return NULL; | |
1608 if (!t->is_con()) return NULL; | |
1609 intptr_t raw_count = t->get_con(); | |
1610 intptr_t size = raw_count; | |
1611 if (!Matcher::init_array_count_is_in_bytes) size *= unit; | |
1612 // Clearing nothing uses the Identity call. | |
1613 // Negative clears are possible on dead ClearArrays | |
1614 // (see jck test stmt114.stmt11402.val). | |
1615 if (size <= 0 || size % unit != 0) return NULL; | |
1616 intptr_t count = size / unit; | |
1617 // Length too long; use fast hardware clear | |
1618 if (size > Matcher::init_array_short_size) return NULL; | |
1619 Node *mem = in(1); | |
1620 if( phase->type(mem)==Type::TOP ) return NULL; | |
1621 Node *adr = in(3); | |
1622 const Type* at = phase->type(adr); | |
1623 if( at==Type::TOP ) return NULL; | |
1624 const TypePtr* atp = at->isa_ptr(); | |
1625 // adjust atp to be the correct array element address type | |
1626 if (atp == NULL) atp = TypePtr::BOTTOM; | |
1627 else atp = atp->add_offset(Type::OffsetBot); | |
1628 // Get base for derived pointer purposes | |
1629 if( adr->Opcode() != Op_AddP ) Unimplemented(); | |
1630 Node *base = adr->in(1); | |
1631 | |
1632 Node *zero = phase->makecon(TypeLong::ZERO); | |
1633 Node *off = phase->MakeConX(BytesPerLong); | |
1634 mem = new (phase->C, 4) StoreLNode(in(0),mem,adr,atp,zero); | |
1635 count--; | |
1636 while( count-- ) { | |
1637 mem = phase->transform(mem); | |
1638 adr = phase->transform(new (phase->C, 4) AddPNode(base,adr,off)); | |
1639 mem = new (phase->C, 4) StoreLNode(in(0),mem,adr,atp,zero); | |
1640 } | |
1641 return mem; | |
1642 } | |
1643 | |
1644 //----------------------------clear_memory------------------------------------- | |
1645 // Generate code to initialize object storage to zero. | |
1646 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest, | |
1647 intptr_t start_offset, | |
1648 Node* end_offset, | |
1649 PhaseGVN* phase) { | |
1650 Compile* C = phase->C; | |
1651 intptr_t offset = start_offset; | |
1652 | |
1653 int unit = BytesPerLong; | |
1654 if ((offset % unit) != 0) { | |
1655 Node* adr = new (C, 4) AddPNode(dest, dest, phase->MakeConX(offset)); | |
1656 adr = phase->transform(adr); | |
1657 const TypePtr* atp = TypeRawPtr::BOTTOM; | |
1658 mem = StoreNode::make(C, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT); | |
1659 mem = phase->transform(mem); | |
1660 offset += BytesPerInt; | |
1661 } | |
1662 assert((offset % unit) == 0, ""); | |
1663 | |
1664 // Initialize the remaining stuff, if any, with a ClearArray. | |
1665 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase); | |
1666 } | |
1667 | |
1668 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest, | |
1669 Node* start_offset, | |
1670 Node* end_offset, | |
1671 PhaseGVN* phase) { | |
1672 Compile* C = phase->C; | |
1673 int unit = BytesPerLong; | |
1674 Node* zbase = start_offset; | |
1675 Node* zend = end_offset; | |
1676 | |
1677 // Scale to the unit required by the CPU: | |
1678 if (!Matcher::init_array_count_is_in_bytes) { | |
1679 Node* shift = phase->intcon(exact_log2(unit)); | |
1680 zbase = phase->transform( new(C,3) URShiftXNode(zbase, shift) ); | |
1681 zend = phase->transform( new(C,3) URShiftXNode(zend, shift) ); | |
1682 } | |
1683 | |
1684 Node* zsize = phase->transform( new(C,3) SubXNode(zend, zbase) ); | |
1685 Node* zinit = phase->zerocon((unit == BytesPerLong) ? T_LONG : T_INT); | |
1686 | |
1687 // Bulk clear double-words | |
1688 Node* adr = phase->transform( new(C,4) AddPNode(dest, dest, start_offset) ); | |
1689 mem = new (C, 4) ClearArrayNode(ctl, mem, zsize, adr); | |
1690 return phase->transform(mem); | |
1691 } | |
1692 | |
1693 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest, | |
1694 intptr_t start_offset, | |
1695 intptr_t end_offset, | |
1696 PhaseGVN* phase) { | |
1697 Compile* C = phase->C; | |
1698 assert((end_offset % BytesPerInt) == 0, "odd end offset"); | |
1699 intptr_t done_offset = end_offset; | |
1700 if ((done_offset % BytesPerLong) != 0) { | |
1701 done_offset -= BytesPerInt; | |
1702 } | |
1703 if (done_offset > start_offset) { | |
1704 mem = clear_memory(ctl, mem, dest, | |
1705 start_offset, phase->MakeConX(done_offset), phase); | |
1706 } | |
1707 if (done_offset < end_offset) { // emit the final 32-bit store | |
1708 Node* adr = new (C, 4) AddPNode(dest, dest, phase->MakeConX(done_offset)); | |
1709 adr = phase->transform(adr); | |
1710 const TypePtr* atp = TypeRawPtr::BOTTOM; | |
1711 mem = StoreNode::make(C, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT); | |
1712 mem = phase->transform(mem); | |
1713 done_offset += BytesPerInt; | |
1714 } | |
1715 assert(done_offset == end_offset, ""); | |
1716 return mem; | |
1717 } | |
1718 | |
1719 //============================================================================= | |
1720 // Do we match on this edge? No memory edges | |
1721 uint StrCompNode::match_edge(uint idx) const { | |
1722 return idx == 5 || idx == 6; | |
1723 } | |
1724 | |
1725 //------------------------------Ideal------------------------------------------ | |
1726 // Return a node which is more "ideal" than the current node. Strip out | |
1727 // control copies | |
1728 Node *StrCompNode::Ideal(PhaseGVN *phase, bool can_reshape){ | |
1729 return remove_dead_region(phase, can_reshape) ? this : NULL; | |
1730 } | |
1731 | |
1732 | |
1733 //============================================================================= | |
1734 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent) | |
1735 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)), | |
1736 _adr_type(C->get_adr_type(alias_idx)) | |
1737 { | |
1738 init_class_id(Class_MemBar); | |
1739 Node* top = C->top(); | |
1740 init_req(TypeFunc::I_O,top); | |
1741 init_req(TypeFunc::FramePtr,top); | |
1742 init_req(TypeFunc::ReturnAdr,top); | |
1743 if (precedent != NULL) | |
1744 init_req(TypeFunc::Parms, precedent); | |
1745 } | |
1746 | |
1747 //------------------------------cmp-------------------------------------------- | |
1748 uint MemBarNode::hash() const { return NO_HASH; } | |
1749 uint MemBarNode::cmp( const Node &n ) const { | |
1750 return (&n == this); // Always fail except on self | |
1751 } | |
1752 | |
1753 //------------------------------make------------------------------------------- | |
1754 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) { | |
1755 int len = Precedent + (pn == NULL? 0: 1); | |
1756 switch (opcode) { | |
1757 case Op_MemBarAcquire: return new(C, len) MemBarAcquireNode(C, atp, pn); | |
1758 case Op_MemBarRelease: return new(C, len) MemBarReleaseNode(C, atp, pn); | |
1759 case Op_MemBarVolatile: return new(C, len) MemBarVolatileNode(C, atp, pn); | |
1760 case Op_MemBarCPUOrder: return new(C, len) MemBarCPUOrderNode(C, atp, pn); | |
1761 case Op_Initialize: return new(C, len) InitializeNode(C, atp, pn); | |
1762 default: ShouldNotReachHere(); return NULL; | |
1763 } | |
1764 } | |
1765 | |
1766 //------------------------------Ideal------------------------------------------ | |
1767 // Return a node which is more "ideal" than the current node. Strip out | |
1768 // control copies | |
1769 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) { | |
1770 if (remove_dead_region(phase, can_reshape)) return this; | |
1771 return NULL; | |
1772 } | |
1773 | |
1774 //------------------------------Value------------------------------------------ | |
1775 const Type *MemBarNode::Value( PhaseTransform *phase ) const { | |
1776 if( !in(0) ) return Type::TOP; | |
1777 if( phase->type(in(0)) == Type::TOP ) | |
1778 return Type::TOP; | |
1779 return TypeTuple::MEMBAR; | |
1780 } | |
1781 | |
1782 //------------------------------match------------------------------------------ | |
1783 // Construct projections for memory. | |
1784 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) { | |
1785 switch (proj->_con) { | |
1786 case TypeFunc::Control: | |
1787 case TypeFunc::Memory: | |
1788 return new (m->C, 1) MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj); | |
1789 } | |
1790 ShouldNotReachHere(); | |
1791 return NULL; | |
1792 } | |
1793 | |
1794 //===========================InitializeNode==================================== | |
1795 // SUMMARY: | |
1796 // This node acts as a memory barrier on raw memory, after some raw stores. | |
1797 // The 'cooked' oop value feeds from the Initialize, not the Allocation. | |
1798 // The Initialize can 'capture' suitably constrained stores as raw inits. | |
1799 // It can coalesce related raw stores into larger units (called 'tiles'). | |
1800 // It can avoid zeroing new storage for memory units which have raw inits. | |
1801 // At macro-expansion, it is marked 'complete', and does not optimize further. | |
1802 // | |
1803 // EXAMPLE: | |
1804 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine. | |
1805 // ctl = incoming control; mem* = incoming memory | |
1806 // (Note: A star * on a memory edge denotes I/O and other standard edges.) | |
1807 // First allocate uninitialized memory and fill in the header: | |
1808 // alloc = (Allocate ctl mem* 16 #short[].klass ...) | |
1809 // ctl := alloc.Control; mem* := alloc.Memory* | |
1810 // rawmem = alloc.Memory; rawoop = alloc.RawAddress | |
1811 // Then initialize to zero the non-header parts of the raw memory block: | |
1812 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress) | |
1813 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory | |
1814 // After the initialize node executes, the object is ready for service: | |
1815 // oop := (CheckCastPP init.Control alloc.RawAddress #short[]) | |
1816 // Suppose its body is immediately initialized as {1,2}: | |
1817 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1) | |
1818 // store2 = (StoreC init.Control store1 (+ oop 14) 2) | |
1819 // mem.SLICE(#short[*]) := store2 | |
1820 // | |
1821 // DETAILS: | |
1822 // An InitializeNode collects and isolates object initialization after | |
1823 // an AllocateNode and before the next possible safepoint. As a | |
1824 // memory barrier (MemBarNode), it keeps critical stores from drifting | |
1825 // down past any safepoint or any publication of the allocation. | |
1826 // Before this barrier, a newly-allocated object may have uninitialized bits. | |
1827 // After this barrier, it may be treated as a real oop, and GC is allowed. | |
1828 // | |
1829 // The semantics of the InitializeNode include an implicit zeroing of | |
1830 // the new object from object header to the end of the object. | |
1831 // (The object header and end are determined by the AllocateNode.) | |
1832 // | |
1833 // Certain stores may be added as direct inputs to the InitializeNode. | |
1834 // These stores must update raw memory, and they must be to addresses | |
1835 // derived from the raw address produced by AllocateNode, and with | |
1836 // a constant offset. They must be ordered by increasing offset. | |
1837 // The first one is at in(RawStores), the last at in(req()-1). | |
1838 // Unlike most memory operations, they are not linked in a chain, | |
1839 // but are displayed in parallel as users of the rawmem output of | |
1840 // the allocation. | |
1841 // | |
1842 // (See comments in InitializeNode::capture_store, which continue | |
1843 // the example given above.) | |
1844 // | |
1845 // When the associated Allocate is macro-expanded, the InitializeNode | |
1846 // may be rewritten to optimize collected stores. A ClearArrayNode | |
1847 // may also be created at that point to represent any required zeroing. | |
1848 // The InitializeNode is then marked 'complete', prohibiting further | |
1849 // capturing of nearby memory operations. | |
1850 // | |
1851 // During macro-expansion, all captured initializations which store | |
1852 // constant values of 32 bits or smaller are coalesced (if advantagous) | |
1853 // into larger 'tiles' 32 or 64 bits. This allows an object to be | |
1854 // initialized in fewer memory operations. Memory words which are | |
1855 // covered by neither tiles nor non-constant stores are pre-zeroed | |
1856 // by explicit stores of zero. (The code shape happens to do all | |
1857 // zeroing first, then all other stores, with both sequences occurring | |
1858 // in order of ascending offsets.) | |
1859 // | |
1860 // Alternatively, code may be inserted between an AllocateNode and its | |
1861 // InitializeNode, to perform arbitrary initialization of the new object. | |
1862 // E.g., the object copying intrinsics insert complex data transfers here. | |
1863 // The initialization must then be marked as 'complete' disable the | |
1864 // built-in zeroing semantics and the collection of initializing stores. | |
1865 // | |
1866 // While an InitializeNode is incomplete, reads from the memory state | |
1867 // produced by it are optimizable if they match the control edge and | |
1868 // new oop address associated with the allocation/initialization. | |
1869 // They return a stored value (if the offset matches) or else zero. | |
1870 // A write to the memory state, if it matches control and address, | |
1871 // and if it is to a constant offset, may be 'captured' by the | |
1872 // InitializeNode. It is cloned as a raw memory operation and rewired | |
1873 // inside the initialization, to the raw oop produced by the allocation. | |
1874 // Operations on addresses which are provably distinct (e.g., to | |
1875 // other AllocateNodes) are allowed to bypass the initialization. | |
1876 // | |
1877 // The effect of all this is to consolidate object initialization | |
1878 // (both arrays and non-arrays, both piecewise and bulk) into a | |
1879 // single location, where it can be optimized as a unit. | |
1880 // | |
1881 // Only stores with an offset less than TrackedInitializationLimit words | |
1882 // will be considered for capture by an InitializeNode. This puts a | |
1883 // reasonable limit on the complexity of optimized initializations. | |
1884 | |
1885 //---------------------------InitializeNode------------------------------------ | |
1886 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop) | |
1887 : _is_complete(false), | |
1888 MemBarNode(C, adr_type, rawoop) | |
1889 { | |
1890 init_class_id(Class_Initialize); | |
1891 | |
1892 assert(adr_type == Compile::AliasIdxRaw, "only valid atp"); | |
1893 assert(in(RawAddress) == rawoop, "proper init"); | |
1894 // Note: allocation() can be NULL, for secondary initialization barriers | |
1895 } | |
1896 | |
1897 // Since this node is not matched, it will be processed by the | |
1898 // register allocator. Declare that there are no constraints | |
1899 // on the allocation of the RawAddress edge. | |
1900 const RegMask &InitializeNode::in_RegMask(uint idx) const { | |
1901 // This edge should be set to top, by the set_complete. But be conservative. | |
1902 if (idx == InitializeNode::RawAddress) | |
1903 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]); | |
1904 return RegMask::Empty; | |
1905 } | |
1906 | |
1907 Node* InitializeNode::memory(uint alias_idx) { | |
1908 Node* mem = in(Memory); | |
1909 if (mem->is_MergeMem()) { | |
1910 return mem->as_MergeMem()->memory_at(alias_idx); | |
1911 } else { | |
1912 // incoming raw memory is not split | |
1913 return mem; | |
1914 } | |
1915 } | |
1916 | |
1917 bool InitializeNode::is_non_zero() { | |
1918 if (is_complete()) return false; | |
1919 remove_extra_zeroes(); | |
1920 return (req() > RawStores); | |
1921 } | |
1922 | |
1923 void InitializeNode::set_complete(PhaseGVN* phase) { | |
1924 assert(!is_complete(), "caller responsibility"); | |
1925 _is_complete = true; | |
1926 | |
1927 // After this node is complete, it contains a bunch of | |
1928 // raw-memory initializations. There is no need for | |
1929 // it to have anything to do with non-raw memory effects. | |
1930 // Therefore, tell all non-raw users to re-optimize themselves, | |
1931 // after skipping the memory effects of this initialization. | |
1932 PhaseIterGVN* igvn = phase->is_IterGVN(); | |
1933 if (igvn) igvn->add_users_to_worklist(this); | |
1934 } | |
1935 | |
1936 // convenience function | |
1937 // return false if the init contains any stores already | |
1938 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) { | |
1939 InitializeNode* init = initialization(); | |
1940 if (init == NULL || init->is_complete()) return false; | |
1941 init->remove_extra_zeroes(); | |
1942 // for now, if this allocation has already collected any inits, bail: | |
1943 if (init->is_non_zero()) return false; | |
1944 init->set_complete(phase); | |
1945 return true; | |
1946 } | |
1947 | |
1948 void InitializeNode::remove_extra_zeroes() { | |
1949 if (req() == RawStores) return; | |
1950 Node* zmem = zero_memory(); | |
1951 uint fill = RawStores; | |
1952 for (uint i = fill; i < req(); i++) { | |
1953 Node* n = in(i); | |
1954 if (n->is_top() || n == zmem) continue; // skip | |
1955 if (fill < i) set_req(fill, n); // compact | |
1956 ++fill; | |
1957 } | |
1958 // delete any empty spaces created: | |
1959 while (fill < req()) { | |
1960 del_req(fill); | |
1961 } | |
1962 } | |
1963 | |
1964 // Helper for remembering which stores go with which offsets. | |
1965 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) { | |
1966 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node | |
1967 intptr_t offset = -1; | |
1968 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address), | |
1969 phase, offset); | |
1970 if (base == NULL) return -1; // something is dead, | |
1971 if (offset < 0) return -1; // dead, dead | |
1972 return offset; | |
1973 } | |
1974 | |
1975 // Helper for proving that an initialization expression is | |
1976 // "simple enough" to be folded into an object initialization. | |
1977 // Attempts to prove that a store's initial value 'n' can be captured | |
1978 // within the initialization without creating a vicious cycle, such as: | |
1979 // { Foo p = new Foo(); p.next = p; } | |
1980 // True for constants and parameters and small combinations thereof. | |
1981 bool InitializeNode::detect_init_independence(Node* n, | |
1982 bool st_is_pinned, | |
1983 int& count) { | |
1984 if (n == NULL) return true; // (can this really happen?) | |
1985 if (n->is_Proj()) n = n->in(0); | |
1986 if (n == this) return false; // found a cycle | |
1987 if (n->is_Con()) return true; | |
1988 if (n->is_Start()) return true; // params, etc., are OK | |
1989 if (n->is_Root()) return true; // even better | |
1990 | |
1991 Node* ctl = n->in(0); | |
1992 if (ctl != NULL && !ctl->is_top()) { | |
1993 if (ctl->is_Proj()) ctl = ctl->in(0); | |
1994 if (ctl == this) return false; | |
1995 | |
1996 // If we already know that the enclosing memory op is pinned right after | |
1997 // the init, then any control flow that the store has picked up | |
1998 // must have preceded the init, or else be equal to the init. | |
1999 // Even after loop optimizations (which might change control edges) | |
2000 // a store is never pinned *before* the availability of its inputs. | |
2001 if (!MemNode::detect_dominating_control(ctl, this->in(0))) | |
2002 return false; // failed to prove a good control | |
2003 | |
2004 } | |
2005 | |
2006 // Check data edges for possible dependencies on 'this'. | |
2007 if ((count += 1) > 20) return false; // complexity limit | |
2008 for (uint i = 1; i < n->req(); i++) { | |
2009 Node* m = n->in(i); | |
2010 if (m == NULL || m == n || m->is_top()) continue; | |
2011 uint first_i = n->find_edge(m); | |
2012 if (i != first_i) continue; // process duplicate edge just once | |
2013 if (!detect_init_independence(m, st_is_pinned, count)) { | |
2014 return false; | |
2015 } | |
2016 } | |
2017 | |
2018 return true; | |
2019 } | |
2020 | |
2021 // Here are all the checks a Store must pass before it can be moved into | |
2022 // an initialization. Returns zero if a check fails. | |
2023 // On success, returns the (constant) offset to which the store applies, | |
2024 // within the initialized memory. | |
2025 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase) { | |
2026 const int FAIL = 0; | |
2027 if (st->req() != MemNode::ValueIn + 1) | |
2028 return FAIL; // an inscrutable StoreNode (card mark?) | |
2029 Node* ctl = st->in(MemNode::Control); | |
2030 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this)) | |
2031 return FAIL; // must be unconditional after the initialization | |
2032 Node* mem = st->in(MemNode::Memory); | |
2033 if (!(mem->is_Proj() && mem->in(0) == this)) | |
2034 return FAIL; // must not be preceded by other stores | |
2035 Node* adr = st->in(MemNode::Address); | |
2036 intptr_t offset; | |
2037 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset); | |
2038 if (alloc == NULL) | |
2039 return FAIL; // inscrutable address | |
2040 if (alloc != allocation()) | |
2041 return FAIL; // wrong allocation! (store needs to float up) | |
2042 Node* val = st->in(MemNode::ValueIn); | |
2043 int complexity_count = 0; | |
2044 if (!detect_init_independence(val, true, complexity_count)) | |
2045 return FAIL; // stored value must be 'simple enough' | |
2046 | |
2047 return offset; // success | |
2048 } | |
2049 | |
2050 // Find the captured store in(i) which corresponds to the range | |
2051 // [start..start+size) in the initialized object. | |
2052 // If there is one, return its index i. If there isn't, return the | |
2053 // negative of the index where it should be inserted. | |
2054 // Return 0 if the queried range overlaps an initialization boundary | |
2055 // or if dead code is encountered. | |
2056 // If size_in_bytes is zero, do not bother with overlap checks. | |
2057 int InitializeNode::captured_store_insertion_point(intptr_t start, | |
2058 int size_in_bytes, | |
2059 PhaseTransform* phase) { | |
2060 const int FAIL = 0, MAX_STORE = BytesPerLong; | |
2061 | |
2062 if (is_complete()) | |
2063 return FAIL; // arraycopy got here first; punt | |
2064 | |
2065 assert(allocation() != NULL, "must be present"); | |
2066 | |
2067 // no negatives, no header fields: | |
2068 if (start < (intptr_t) sizeof(oopDesc)) return FAIL; | |
2069 if (start < (intptr_t) sizeof(arrayOopDesc) && | |
2070 start < (intptr_t) allocation()->minimum_header_size()) return FAIL; | |
2071 | |
2072 // after a certain size, we bail out on tracking all the stores: | |
2073 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize); | |
2074 if (start >= ti_limit) return FAIL; | |
2075 | |
2076 for (uint i = InitializeNode::RawStores, limit = req(); ; ) { | |
2077 if (i >= limit) return -(int)i; // not found; here is where to put it | |
2078 | |
2079 Node* st = in(i); | |
2080 intptr_t st_off = get_store_offset(st, phase); | |
2081 if (st_off < 0) { | |
2082 if (st != zero_memory()) { | |
2083 return FAIL; // bail out if there is dead garbage | |
2084 } | |
2085 } else if (st_off > start) { | |
2086 // ...we are done, since stores are ordered | |
2087 if (st_off < start + size_in_bytes) { | |
2088 return FAIL; // the next store overlaps | |
2089 } | |
2090 return -(int)i; // not found; here is where to put it | |
2091 } else if (st_off < start) { | |
2092 if (size_in_bytes != 0 && | |
2093 start < st_off + MAX_STORE && | |
2094 start < st_off + st->as_Store()->memory_size()) { | |
2095 return FAIL; // the previous store overlaps | |
2096 } | |
2097 } else { | |
2098 if (size_in_bytes != 0 && | |
2099 st->as_Store()->memory_size() != size_in_bytes) { | |
2100 return FAIL; // mismatched store size | |
2101 } | |
2102 return i; | |
2103 } | |
2104 | |
2105 ++i; | |
2106 } | |
2107 } | |
2108 | |
2109 // Look for a captured store which initializes at the offset 'start' | |
2110 // with the given size. If there is no such store, and no other | |
2111 // initialization interferes, then return zero_memory (the memory | |
2112 // projection of the AllocateNode). | |
2113 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes, | |
2114 PhaseTransform* phase) { | |
2115 assert(stores_are_sane(phase), ""); | |
2116 int i = captured_store_insertion_point(start, size_in_bytes, phase); | |
2117 if (i == 0) { | |
2118 return NULL; // something is dead | |
2119 } else if (i < 0) { | |
2120 return zero_memory(); // just primordial zero bits here | |
2121 } else { | |
2122 Node* st = in(i); // here is the store at this position | |
2123 assert(get_store_offset(st->as_Store(), phase) == start, "sanity"); | |
2124 return st; | |
2125 } | |
2126 } | |
2127 | |
2128 // Create, as a raw pointer, an address within my new object at 'offset'. | |
2129 Node* InitializeNode::make_raw_address(intptr_t offset, | |
2130 PhaseTransform* phase) { | |
2131 Node* addr = in(RawAddress); | |
2132 if (offset != 0) { | |
2133 Compile* C = phase->C; | |
2134 addr = phase->transform( new (C, 4) AddPNode(C->top(), addr, | |
2135 phase->MakeConX(offset)) ); | |
2136 } | |
2137 return addr; | |
2138 } | |
2139 | |
2140 // Clone the given store, converting it into a raw store | |
2141 // initializing a field or element of my new object. | |
2142 // Caller is responsible for retiring the original store, | |
2143 // with subsume_node or the like. | |
2144 // | |
2145 // From the example above InitializeNode::InitializeNode, | |
2146 // here are the old stores to be captured: | |
2147 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1) | |
2148 // store2 = (StoreC init.Control store1 (+ oop 14) 2) | |
2149 // | |
2150 // Here is the changed code; note the extra edges on init: | |
2151 // alloc = (Allocate ...) | |
2152 // rawoop = alloc.RawAddress | |
2153 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1) | |
2154 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2) | |
2155 // init = (Initialize alloc.Control alloc.Memory rawoop | |
2156 // rawstore1 rawstore2) | |
2157 // | |
2158 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start, | |
2159 PhaseTransform* phase) { | |
2160 assert(stores_are_sane(phase), ""); | |
2161 | |
2162 if (start < 0) return NULL; | |
2163 assert(can_capture_store(st, phase) == start, "sanity"); | |
2164 | |
2165 Compile* C = phase->C; | |
2166 int size_in_bytes = st->memory_size(); | |
2167 int i = captured_store_insertion_point(start, size_in_bytes, phase); | |
2168 if (i == 0) return NULL; // bail out | |
2169 Node* prev_mem = NULL; // raw memory for the captured store | |
2170 if (i > 0) { | |
2171 prev_mem = in(i); // there is a pre-existing store under this one | |
2172 set_req(i, C->top()); // temporarily disconnect it | |
2173 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect. | |
2174 } else { | |
2175 i = -i; // no pre-existing store | |
2176 prev_mem = zero_memory(); // a slice of the newly allocated object | |
2177 if (i > InitializeNode::RawStores && in(i-1) == prev_mem) | |
2178 set_req(--i, C->top()); // reuse this edge; it has been folded away | |
2179 else | |
2180 ins_req(i, C->top()); // build a new edge | |
2181 } | |
2182 Node* new_st = st->clone(); | |
2183 new_st->set_req(MemNode::Control, in(Control)); | |
2184 new_st->set_req(MemNode::Memory, prev_mem); | |
2185 new_st->set_req(MemNode::Address, make_raw_address(start, phase)); | |
2186 new_st = phase->transform(new_st); | |
2187 | |
2188 // At this point, new_st might have swallowed a pre-existing store | |
2189 // at the same offset, or perhaps new_st might have disappeared, | |
2190 // if it redundantly stored the same value (or zero to fresh memory). | |
2191 | |
2192 // In any case, wire it in: | |
2193 set_req(i, new_st); | |
2194 | |
2195 // The caller may now kill the old guy. | |
2196 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase)); | |
2197 assert(check_st == new_st || check_st == NULL, "must be findable"); | |
2198 assert(!is_complete(), ""); | |
2199 return new_st; | |
2200 } | |
2201 | |
2202 static bool store_constant(jlong* tiles, int num_tiles, | |
2203 intptr_t st_off, int st_size, | |
2204 jlong con) { | |
2205 if ((st_off & (st_size-1)) != 0) | |
2206 return false; // strange store offset (assume size==2**N) | |
2207 address addr = (address)tiles + st_off; | |
2208 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob"); | |
2209 switch (st_size) { | |
2210 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break; | |
2211 case sizeof(jchar): *(jchar*) addr = (jchar) con; break; | |
2212 case sizeof(jint): *(jint*) addr = (jint) con; break; | |
2213 case sizeof(jlong): *(jlong*) addr = (jlong) con; break; | |
2214 default: return false; // strange store size (detect size!=2**N here) | |
2215 } | |
2216 return true; // return success to caller | |
2217 } | |
2218 | |
2219 // Coalesce subword constants into int constants and possibly | |
2220 // into long constants. The goal, if the CPU permits, | |
2221 // is to initialize the object with a small number of 64-bit tiles. | |
2222 // Also, convert floating-point constants to bit patterns. | |
2223 // Non-constants are not relevant to this pass. | |
2224 // | |
2225 // In terms of the running example on InitializeNode::InitializeNode | |
2226 // and InitializeNode::capture_store, here is the transformation | |
2227 // of rawstore1 and rawstore2 into rawstore12: | |
2228 // alloc = (Allocate ...) | |
2229 // rawoop = alloc.RawAddress | |
2230 // tile12 = 0x00010002 | |
2231 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12) | |
2232 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12) | |
2233 // | |
2234 void | |
2235 InitializeNode::coalesce_subword_stores(intptr_t header_size, | |
2236 Node* size_in_bytes, | |
2237 PhaseGVN* phase) { | |
2238 Compile* C = phase->C; | |
2239 | |
2240 assert(stores_are_sane(phase), ""); | |
2241 // Note: After this pass, they are not completely sane, | |
2242 // since there may be some overlaps. | |
2243 | |
2244 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0; | |
2245 | |
2246 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize); | |
2247 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit); | |
2248 size_limit = MIN2(size_limit, ti_limit); | |
2249 size_limit = align_size_up(size_limit, BytesPerLong); | |
2250 int num_tiles = size_limit / BytesPerLong; | |
2251 | |
2252 // allocate space for the tile map: | |
2253 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small | |
2254 jlong tiles_buf[small_len]; | |
2255 Node* nodes_buf[small_len]; | |
2256 jlong inits_buf[small_len]; | |
2257 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0] | |
2258 : NEW_RESOURCE_ARRAY(jlong, num_tiles)); | |
2259 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0] | |
2260 : NEW_RESOURCE_ARRAY(Node*, num_tiles)); | |
2261 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0] | |
2262 : NEW_RESOURCE_ARRAY(jlong, num_tiles)); | |
2263 // tiles: exact bitwise model of all primitive constants | |
2264 // nodes: last constant-storing node subsumed into the tiles model | |
2265 // inits: which bytes (in each tile) are touched by any initializations | |
2266 | |
2267 //// Pass A: Fill in the tile model with any relevant stores. | |
2268 | |
2269 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles); | |
2270 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles); | |
2271 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles); | |
2272 Node* zmem = zero_memory(); // initially zero memory state | |
2273 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) { | |
2274 Node* st = in(i); | |
2275 intptr_t st_off = get_store_offset(st, phase); | |
2276 | |
2277 // Figure out the store's offset and constant value: | |
2278 if (st_off < header_size) continue; //skip (ignore header) | |
2279 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain) | |
2280 int st_size = st->as_Store()->memory_size(); | |
2281 if (st_off + st_size > size_limit) break; | |
2282 | |
2283 // Record which bytes are touched, whether by constant or not. | |
2284 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1)) | |
2285 continue; // skip (strange store size) | |
2286 | |
2287 const Type* val = phase->type(st->in(MemNode::ValueIn)); | |
2288 if (!val->singleton()) continue; //skip (non-con store) | |
2289 BasicType type = val->basic_type(); | |
2290 | |
2291 jlong con = 0; | |
2292 switch (type) { | |
2293 case T_INT: con = val->is_int()->get_con(); break; | |
2294 case T_LONG: con = val->is_long()->get_con(); break; | |
2295 case T_FLOAT: con = jint_cast(val->getf()); break; | |
2296 case T_DOUBLE: con = jlong_cast(val->getd()); break; | |
2297 default: continue; //skip (odd store type) | |
2298 } | |
2299 | |
2300 if (type == T_LONG && Matcher::isSimpleConstant64(con) && | |
2301 st->Opcode() == Op_StoreL) { | |
2302 continue; // This StoreL is already optimal. | |
2303 } | |
2304 | |
2305 // Store down the constant. | |
2306 store_constant(tiles, num_tiles, st_off, st_size, con); | |
2307 | |
2308 intptr_t j = st_off >> LogBytesPerLong; | |
2309 | |
2310 if (type == T_INT && st_size == BytesPerInt | |
2311 && (st_off & BytesPerInt) == BytesPerInt) { | |
2312 jlong lcon = tiles[j]; | |
2313 if (!Matcher::isSimpleConstant64(lcon) && | |
2314 st->Opcode() == Op_StoreI) { | |
2315 // This StoreI is already optimal by itself. | |
2316 jint* intcon = (jint*) &tiles[j]; | |
2317 intcon[1] = 0; // undo the store_constant() | |
2318 | |
2319 // If the previous store is also optimal by itself, back up and | |
2320 // undo the action of the previous loop iteration... if we can. | |
2321 // But if we can't, just let the previous half take care of itself. | |
2322 st = nodes[j]; | |
2323 st_off -= BytesPerInt; | |
2324 con = intcon[0]; | |
2325 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) { | |
2326 assert(st_off >= header_size, "still ignoring header"); | |
2327 assert(get_store_offset(st, phase) == st_off, "must be"); | |
2328 assert(in(i-1) == zmem, "must be"); | |
2329 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn))); | |
2330 assert(con == tcon->is_int()->get_con(), "must be"); | |
2331 // Undo the effects of the previous loop trip, which swallowed st: | |
2332 intcon[0] = 0; // undo store_constant() | |
2333 set_req(i-1, st); // undo set_req(i, zmem) | |
2334 nodes[j] = NULL; // undo nodes[j] = st | |
2335 --old_subword; // undo ++old_subword | |
2336 } | |
2337 continue; // This StoreI is already optimal. | |
2338 } | |
2339 } | |
2340 | |
2341 // This store is not needed. | |
2342 set_req(i, zmem); | |
2343 nodes[j] = st; // record for the moment | |
2344 if (st_size < BytesPerLong) // something has changed | |
2345 ++old_subword; // includes int/float, but who's counting... | |
2346 else ++old_long; | |
2347 } | |
2348 | |
2349 if ((old_subword + old_long) == 0) | |
2350 return; // nothing more to do | |
2351 | |
2352 //// Pass B: Convert any non-zero tiles into optimal constant stores. | |
2353 // Be sure to insert them before overlapping non-constant stores. | |
2354 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.) | |
2355 for (int j = 0; j < num_tiles; j++) { | |
2356 jlong con = tiles[j]; | |
2357 jlong init = inits[j]; | |
2358 if (con == 0) continue; | |
2359 jint con0, con1; // split the constant, address-wise | |
2360 jint init0, init1; // split the init map, address-wise | |
2361 { union { jlong con; jint intcon[2]; } u; | |
2362 u.con = con; | |
2363 con0 = u.intcon[0]; | |
2364 con1 = u.intcon[1]; | |
2365 u.con = init; | |
2366 init0 = u.intcon[0]; | |
2367 init1 = u.intcon[1]; | |
2368 } | |
2369 | |
2370 Node* old = nodes[j]; | |
2371 assert(old != NULL, "need the prior store"); | |
2372 intptr_t offset = (j * BytesPerLong); | |
2373 | |
2374 bool split = !Matcher::isSimpleConstant64(con); | |
2375 | |
2376 if (offset < header_size) { | |
2377 assert(offset + BytesPerInt >= header_size, "second int counts"); | |
2378 assert(*(jint*)&tiles[j] == 0, "junk in header"); | |
2379 split = true; // only the second word counts | |
2380 // Example: int a[] = { 42 ... } | |
2381 } else if (con0 == 0 && init0 == -1) { | |
2382 split = true; // first word is covered by full inits | |
2383 // Example: int a[] = { ... foo(), 42 ... } | |
2384 } else if (con1 == 0 && init1 == -1) { | |
2385 split = true; // second word is covered by full inits | |
2386 // Example: int a[] = { ... 42, foo() ... } | |
2387 } | |
2388 | |
2389 // Here's a case where init0 is neither 0 nor -1: | |
2390 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... } | |
2391 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF. | |
2392 // In this case the tile is not split; it is (jlong)42. | |
2393 // The big tile is stored down, and then the foo() value is inserted. | |
2394 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.) | |
2395 | |
2396 Node* ctl = old->in(MemNode::Control); | |
2397 Node* adr = make_raw_address(offset, phase); | |
2398 const TypePtr* atp = TypeRawPtr::BOTTOM; | |
2399 | |
2400 // One or two coalesced stores to plop down. | |
2401 Node* st[2]; | |
2402 intptr_t off[2]; | |
2403 int nst = 0; | |
2404 if (!split) { | |
2405 ++new_long; | |
2406 off[nst] = offset; | |
2407 st[nst++] = StoreNode::make(C, ctl, zmem, adr, atp, | |
2408 phase->longcon(con), T_LONG); | |
2409 } else { | |
2410 // Omit either if it is a zero. | |
2411 if (con0 != 0) { | |
2412 ++new_int; | |
2413 off[nst] = offset; | |
2414 st[nst++] = StoreNode::make(C, ctl, zmem, adr, atp, | |
2415 phase->intcon(con0), T_INT); | |
2416 } | |
2417 if (con1 != 0) { | |
2418 ++new_int; | |
2419 offset += BytesPerInt; | |
2420 adr = make_raw_address(offset, phase); | |
2421 off[nst] = offset; | |
2422 st[nst++] = StoreNode::make(C, ctl, zmem, adr, atp, | |
2423 phase->intcon(con1), T_INT); | |
2424 } | |
2425 } | |
2426 | |
2427 // Insert second store first, then the first before the second. | |
2428 // Insert each one just before any overlapping non-constant stores. | |
2429 while (nst > 0) { | |
2430 Node* st1 = st[--nst]; | |
2431 C->copy_node_notes_to(st1, old); | |
2432 st1 = phase->transform(st1); | |
2433 offset = off[nst]; | |
2434 assert(offset >= header_size, "do not smash header"); | |
2435 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase); | |
2436 guarantee(ins_idx != 0, "must re-insert constant store"); | |
2437 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap | |
2438 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem) | |
2439 set_req(--ins_idx, st1); | |
2440 else | |
2441 ins_req(ins_idx, st1); | |
2442 } | |
2443 } | |
2444 | |
2445 if (PrintCompilation && WizardMode) | |
2446 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long", | |
2447 old_subword, old_long, new_int, new_long); | |
2448 if (C->log() != NULL) | |
2449 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'", | |
2450 old_subword, old_long, new_int, new_long); | |
2451 | |
2452 // Clean up any remaining occurrences of zmem: | |
2453 remove_extra_zeroes(); | |
2454 } | |
2455 | |
2456 // Explore forward from in(start) to find the first fully initialized | |
2457 // word, and return its offset. Skip groups of subword stores which | |
2458 // together initialize full words. If in(start) is itself part of a | |
2459 // fully initialized word, return the offset of in(start). If there | |
2460 // are no following full-word stores, or if something is fishy, return | |
2461 // a negative value. | |
2462 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) { | |
2463 int int_map = 0; | |
2464 intptr_t int_map_off = 0; | |
2465 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for | |
2466 | |
2467 for (uint i = start, limit = req(); i < limit; i++) { | |
2468 Node* st = in(i); | |
2469 | |
2470 intptr_t st_off = get_store_offset(st, phase); | |
2471 if (st_off < 0) break; // return conservative answer | |
2472 | |
2473 int st_size = st->as_Store()->memory_size(); | |
2474 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) { | |
2475 return st_off; // we found a complete word init | |
2476 } | |
2477 | |
2478 // update the map: | |
2479 | |
2480 intptr_t this_int_off = align_size_down(st_off, BytesPerInt); | |
2481 if (this_int_off != int_map_off) { | |
2482 // reset the map: | |
2483 int_map = 0; | |
2484 int_map_off = this_int_off; | |
2485 } | |
2486 | |
2487 int subword_off = st_off - this_int_off; | |
2488 int_map |= right_n_bits(st_size) << subword_off; | |
2489 if ((int_map & FULL_MAP) == FULL_MAP) { | |
2490 return this_int_off; // we found a complete word init | |
2491 } | |
2492 | |
2493 // Did this store hit or cross the word boundary? | |
2494 intptr_t next_int_off = align_size_down(st_off + st_size, BytesPerInt); | |
2495 if (next_int_off == this_int_off + BytesPerInt) { | |
2496 // We passed the current int, without fully initializing it. | |
2497 int_map_off = next_int_off; | |
2498 int_map >>= BytesPerInt; | |
2499 } else if (next_int_off > this_int_off + BytesPerInt) { | |
2500 // We passed the current and next int. | |
2501 return this_int_off + BytesPerInt; | |
2502 } | |
2503 } | |
2504 | |
2505 return -1; | |
2506 } | |
2507 | |
2508 | |
2509 // Called when the associated AllocateNode is expanded into CFG. | |
2510 // At this point, we may perform additional optimizations. | |
2511 // Linearize the stores by ascending offset, to make memory | |
2512 // activity as coherent as possible. | |
2513 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr, | |
2514 intptr_t header_size, | |
2515 Node* size_in_bytes, | |
2516 PhaseGVN* phase) { | |
2517 assert(!is_complete(), "not already complete"); | |
2518 assert(stores_are_sane(phase), ""); | |
2519 assert(allocation() != NULL, "must be present"); | |
2520 | |
2521 remove_extra_zeroes(); | |
2522 | |
2523 if (ReduceFieldZeroing || ReduceBulkZeroing) | |
2524 // reduce instruction count for common initialization patterns | |
2525 coalesce_subword_stores(header_size, size_in_bytes, phase); | |
2526 | |
2527 Node* zmem = zero_memory(); // initially zero memory state | |
2528 Node* inits = zmem; // accumulating a linearized chain of inits | |
2529 #ifdef ASSERT | |
2530 intptr_t last_init_off = sizeof(oopDesc); // previous init offset | |
2531 intptr_t last_init_end = sizeof(oopDesc); // previous init offset+size | |
2532 intptr_t last_tile_end = sizeof(oopDesc); // previous tile offset+size | |
2533 #endif | |
2534 intptr_t zeroes_done = header_size; | |
2535 | |
2536 bool do_zeroing = true; // we might give up if inits are very sparse | |
2537 int big_init_gaps = 0; // how many large gaps have we seen? | |
2538 | |
2539 if (ZeroTLAB) do_zeroing = false; | |
2540 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false; | |
2541 | |
2542 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) { | |
2543 Node* st = in(i); | |
2544 intptr_t st_off = get_store_offset(st, phase); | |
2545 if (st_off < 0) | |
2546 break; // unknown junk in the inits | |
2547 if (st->in(MemNode::Memory) != zmem) | |
2548 break; // complicated store chains somehow in list | |
2549 | |
2550 int st_size = st->as_Store()->memory_size(); | |
2551 intptr_t next_init_off = st_off + st_size; | |
2552 | |
2553 if (do_zeroing && zeroes_done < next_init_off) { | |
2554 // See if this store needs a zero before it or under it. | |
2555 intptr_t zeroes_needed = st_off; | |
2556 | |
2557 if (st_size < BytesPerInt) { | |
2558 // Look for subword stores which only partially initialize words. | |
2559 // If we find some, we must lay down some word-level zeroes first, | |
2560 // underneath the subword stores. | |
2561 // | |
2562 // Examples: | |
2563 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s | |
2564 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y | |
2565 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z | |
2566 // | |
2567 // Note: coalesce_subword_stores may have already done this, | |
2568 // if it was prompted by constant non-zero subword initializers. | |
2569 // But this case can still arise with non-constant stores. | |
2570 | |
2571 intptr_t next_full_store = find_next_fullword_store(i, phase); | |
2572 | |
2573 // In the examples above: | |
2574 // in(i) p q r s x y z | |
2575 // st_off 12 13 14 15 12 13 14 | |
2576 // st_size 1 1 1 1 1 1 1 | |
2577 // next_full_s. 12 16 16 16 16 16 16 | |
2578 // z's_done 12 16 16 16 12 16 12 | |
2579 // z's_needed 12 16 16 16 16 16 16 | |
2580 // zsize 0 0 0 0 4 0 4 | |
2581 if (next_full_store < 0) { | |
2582 // Conservative tack: Zero to end of current word. | |
2583 zeroes_needed = align_size_up(zeroes_needed, BytesPerInt); | |
2584 } else { | |
2585 // Zero to beginning of next fully initialized word. | |
2586 // Or, don't zero at all, if we are already in that word. | |
2587 assert(next_full_store >= zeroes_needed, "must go forward"); | |
2588 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary"); | |
2589 zeroes_needed = next_full_store; | |
2590 } | |
2591 } | |
2592 | |
2593 if (zeroes_needed > zeroes_done) { | |
2594 intptr_t zsize = zeroes_needed - zeroes_done; | |
2595 // Do some incremental zeroing on rawmem, in parallel with inits. | |
2596 zeroes_done = align_size_down(zeroes_done, BytesPerInt); | |
2597 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr, | |
2598 zeroes_done, zeroes_needed, | |
2599 phase); | |
2600 zeroes_done = zeroes_needed; | |
2601 if (zsize > Matcher::init_array_short_size && ++big_init_gaps > 2) | |
2602 do_zeroing = false; // leave the hole, next time | |
2603 } | |
2604 } | |
2605 | |
2606 // Collect the store and move on: | |
2607 st->set_req(MemNode::Memory, inits); | |
2608 inits = st; // put it on the linearized chain | |
2609 set_req(i, zmem); // unhook from previous position | |
2610 | |
2611 if (zeroes_done == st_off) | |
2612 zeroes_done = next_init_off; | |
2613 | |
2614 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any"); | |
2615 | |
2616 #ifdef ASSERT | |
2617 // Various order invariants. Weaker than stores_are_sane because | |
2618 // a large constant tile can be filled in by smaller non-constant stores. | |
2619 assert(st_off >= last_init_off, "inits do not reverse"); | |
2620 last_init_off = st_off; | |
2621 const Type* val = NULL; | |
2622 if (st_size >= BytesPerInt && | |
2623 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() && | |
2624 (int)val->basic_type() < (int)T_OBJECT) { | |
2625 assert(st_off >= last_tile_end, "tiles do not overlap"); | |
2626 assert(st_off >= last_init_end, "tiles do not overwrite inits"); | |
2627 last_tile_end = MAX2(last_tile_end, next_init_off); | |
2628 } else { | |
2629 intptr_t st_tile_end = align_size_up(next_init_off, BytesPerLong); | |
2630 assert(st_tile_end >= last_tile_end, "inits stay with tiles"); | |
2631 assert(st_off >= last_init_end, "inits do not overlap"); | |
2632 last_init_end = next_init_off; // it's a non-tile | |
2633 } | |
2634 #endif //ASSERT | |
2635 } | |
2636 | |
2637 remove_extra_zeroes(); // clear out all the zmems left over | |
2638 add_req(inits); | |
2639 | |
2640 if (!ZeroTLAB) { | |
2641 // If anything remains to be zeroed, zero it all now. | |
2642 zeroes_done = align_size_down(zeroes_done, BytesPerInt); | |
2643 // if it is the last unused 4 bytes of an instance, forget about it | |
2644 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint); | |
2645 if (zeroes_done + BytesPerLong >= size_limit) { | |
2646 assert(allocation() != NULL, ""); | |
2647 Node* klass_node = allocation()->in(AllocateNode::KlassNode); | |
2648 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass(); | |
2649 if (zeroes_done == k->layout_helper()) | |
2650 zeroes_done = size_limit; | |
2651 } | |
2652 if (zeroes_done < size_limit) { | |
2653 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr, | |
2654 zeroes_done, size_in_bytes, phase); | |
2655 } | |
2656 } | |
2657 | |
2658 set_complete(phase); | |
2659 return rawmem; | |
2660 } | |
2661 | |
2662 | |
2663 #ifdef ASSERT | |
2664 bool InitializeNode::stores_are_sane(PhaseTransform* phase) { | |
2665 if (is_complete()) | |
2666 return true; // stores could be anything at this point | |
2667 intptr_t last_off = sizeof(oopDesc); | |
2668 for (uint i = InitializeNode::RawStores; i < req(); i++) { | |
2669 Node* st = in(i); | |
2670 intptr_t st_off = get_store_offset(st, phase); | |
2671 if (st_off < 0) continue; // ignore dead garbage | |
2672 if (last_off > st_off) { | |
2673 tty->print_cr("*** bad store offset at %d: %d > %d", i, last_off, st_off); | |
2674 this->dump(2); | |
2675 assert(false, "ascending store offsets"); | |
2676 return false; | |
2677 } | |
2678 last_off = st_off + st->as_Store()->memory_size(); | |
2679 } | |
2680 return true; | |
2681 } | |
2682 #endif //ASSERT | |
2683 | |
2684 | |
2685 | |
2686 | |
2687 //============================MergeMemNode===================================== | |
2688 // | |
2689 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several | |
2690 // contributing store or call operations. Each contributor provides the memory | |
2691 // state for a particular "alias type" (see Compile::alias_type). For example, | |
2692 // if a MergeMem has an input X for alias category #6, then any memory reference | |
2693 // to alias category #6 may use X as its memory state input, as an exact equivalent | |
2694 // to using the MergeMem as a whole. | |
2695 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p) | |
2696 // | |
2697 // (Here, the <N> notation gives the index of the relevant adr_type.) | |
2698 // | |
2699 // In one special case (and more cases in the future), alias categories overlap. | |
2700 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory | |
2701 // states. Therefore, if a MergeMem has only one contributing input W for Bot, | |
2702 // it is exactly equivalent to that state W: | |
2703 // MergeMem(<Bot>: W) <==> W | |
2704 // | |
2705 // Usually, the merge has more than one input. In that case, where inputs | |
2706 // overlap (i.e., one is Bot), the narrower alias type determines the memory | |
2707 // state for that type, and the wider alias type (Bot) fills in everywhere else: | |
2708 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p) | |
2709 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p) | |
2710 // | |
2711 // A merge can take a "wide" memory state as one of its narrow inputs. | |
2712 // This simply means that the merge observes out only the relevant parts of | |
2713 // the wide input. That is, wide memory states arriving at narrow merge inputs | |
2714 // are implicitly "filtered" or "sliced" as necessary. (This is rare.) | |
2715 // | |
2716 // These rules imply that MergeMem nodes may cascade (via their <Bot> links), | |
2717 // and that memory slices "leak through": | |
2718 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y) | |
2719 // | |
2720 // But, in such a cascade, repeated memory slices can "block the leak": | |
2721 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y') | |
2722 // | |
2723 // In the last example, Y is not part of the combined memory state of the | |
2724 // outermost MergeMem. The system must, of course, prevent unschedulable | |
2725 // memory states from arising, so you can be sure that the state Y is somehow | |
2726 // a precursor to state Y'. | |
2727 // | |
2728 // | |
2729 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array | |
2730 // of each MergeMemNode array are exactly the numerical alias indexes, including | |
2731 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions | |
2732 // Compile::alias_type (and kin) produce and manage these indexes. | |
2733 // | |
2734 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node. | |
2735 // (Note that this provides quick access to the top node inside MergeMem methods, | |
2736 // without the need to reach out via TLS to Compile::current.) | |
2737 // | |
2738 // As a consequence of what was just described, a MergeMem that represents a full | |
2739 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state, | |
2740 // containing all alias categories. | |
2741 // | |
2742 // MergeMem nodes never (?) have control inputs, so in(0) is NULL. | |
2743 // | |
2744 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either | |
2745 // a memory state for the alias type <N>, or else the top node, meaning that | |
2746 // there is no particular input for that alias type. Note that the length of | |
2747 // a MergeMem is variable, and may be extended at any time to accommodate new | |
2748 // memory states at larger alias indexes. When merges grow, they are of course | |
2749 // filled with "top" in the unused in() positions. | |
2750 // | |
2751 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable. | |
2752 // (Top was chosen because it works smoothly with passes like GCM.) | |
2753 // | |
2754 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is | |
2755 // the type of random VM bits like TLS references.) Since it is always the | |
2756 // first non-Bot memory slice, some low-level loops use it to initialize an | |
2757 // index variable: for (i = AliasIdxRaw; i < req(); i++). | |
2758 // | |
2759 // | |
2760 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns | |
2761 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns | |
2762 // the memory state for alias type <N>, or (if there is no particular slice at <N>, | |
2763 // it returns the base memory. To prevent bugs, memory_at does not accept <Top> | |
2764 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over | |
2765 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited. | |
2766 // | |
2767 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't | |
2768 // really that different from the other memory inputs. An abbreviation called | |
2769 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy. | |
2770 // | |
2771 // | |
2772 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent | |
2773 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi | |
2774 // that "emerges though" the base memory will be marked as excluding the alias types | |
2775 // of the other (narrow-memory) copies which "emerged through" the narrow edges: | |
2776 // | |
2777 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y)) | |
2778 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y)) | |
2779 // | |
2780 // This strange "subtraction" effect is necessary to ensure IGVN convergence. | |
2781 // (It is currently unimplemented.) As you can see, the resulting merge is | |
2782 // actually a disjoint union of memory states, rather than an overlay. | |
2783 // | |
2784 | |
2785 //------------------------------MergeMemNode----------------------------------- | |
2786 Node* MergeMemNode::make_empty_memory() { | |
2787 Node* empty_memory = (Node*) Compile::current()->top(); | |
2788 assert(empty_memory->is_top(), "correct sentinel identity"); | |
2789 return empty_memory; | |
2790 } | |
2791 | |
2792 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) { | |
2793 init_class_id(Class_MergeMem); | |
2794 // all inputs are nullified in Node::Node(int) | |
2795 // set_input(0, NULL); // no control input | |
2796 | |
2797 // Initialize the edges uniformly to top, for starters. | |
2798 Node* empty_mem = make_empty_memory(); | |
2799 for (uint i = Compile::AliasIdxTop; i < req(); i++) { | |
2800 init_req(i,empty_mem); | |
2801 } | |
2802 assert(empty_memory() == empty_mem, ""); | |
2803 | |
2804 if( new_base != NULL && new_base->is_MergeMem() ) { | |
2805 MergeMemNode* mdef = new_base->as_MergeMem(); | |
2806 assert(mdef->empty_memory() == empty_mem, "consistent sentinels"); | |
2807 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) { | |
2808 mms.set_memory(mms.memory2()); | |
2809 } | |
2810 assert(base_memory() == mdef->base_memory(), ""); | |
2811 } else { | |
2812 set_base_memory(new_base); | |
2813 } | |
2814 } | |
2815 | |
2816 // Make a new, untransformed MergeMem with the same base as 'mem'. | |
2817 // If mem is itself a MergeMem, populate the result with the same edges. | |
2818 MergeMemNode* MergeMemNode::make(Compile* C, Node* mem) { | |
2819 return new(C, 1+Compile::AliasIdxRaw) MergeMemNode(mem); | |
2820 } | |
2821 | |
2822 //------------------------------cmp-------------------------------------------- | |
2823 uint MergeMemNode::hash() const { return NO_HASH; } | |
2824 uint MergeMemNode::cmp( const Node &n ) const { | |
2825 return (&n == this); // Always fail except on self | |
2826 } | |
2827 | |
2828 //------------------------------Identity--------------------------------------- | |
2829 Node* MergeMemNode::Identity(PhaseTransform *phase) { | |
2830 // Identity if this merge point does not record any interesting memory | |
2831 // disambiguations. | |
2832 Node* base_mem = base_memory(); | |
2833 Node* empty_mem = empty_memory(); | |
2834 if (base_mem != empty_mem) { // Memory path is not dead? | |
2835 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { | |
2836 Node* mem = in(i); | |
2837 if (mem != empty_mem && mem != base_mem) { | |
2838 return this; // Many memory splits; no change | |
2839 } | |
2840 } | |
2841 } | |
2842 return base_mem; // No memory splits; ID on the one true input | |
2843 } | |
2844 | |
2845 //------------------------------Ideal------------------------------------------ | |
2846 // This method is invoked recursively on chains of MergeMem nodes | |
2847 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) { | |
2848 // Remove chain'd MergeMems | |
2849 // | |
2850 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted | |
2851 // relative to the "in(Bot)". Since we are patching both at the same time, | |
2852 // we have to be careful to read each "in(i)" relative to the old "in(Bot)", | |
2853 // but rewrite each "in(i)" relative to the new "in(Bot)". | |
2854 Node *progress = NULL; | |
2855 | |
2856 | |
2857 Node* old_base = base_memory(); | |
2858 Node* empty_mem = empty_memory(); | |
2859 if (old_base == empty_mem) | |
2860 return NULL; // Dead memory path. | |
2861 | |
2862 MergeMemNode* old_mbase; | |
2863 if (old_base != NULL && old_base->is_MergeMem()) | |
2864 old_mbase = old_base->as_MergeMem(); | |
2865 else | |
2866 old_mbase = NULL; | |
2867 Node* new_base = old_base; | |
2868 | |
2869 // simplify stacked MergeMems in base memory | |
2870 if (old_mbase) new_base = old_mbase->base_memory(); | |
2871 | |
2872 // the base memory might contribute new slices beyond my req() | |
2873 if (old_mbase) grow_to_match(old_mbase); | |
2874 | |
2875 // Look carefully at the base node if it is a phi. | |
2876 PhiNode* phi_base; | |
2877 if (new_base != NULL && new_base->is_Phi()) | |
2878 phi_base = new_base->as_Phi(); | |
2879 else | |
2880 phi_base = NULL; | |
2881 | |
2882 Node* phi_reg = NULL; | |
2883 uint phi_len = (uint)-1; | |
2884 if (phi_base != NULL && !phi_base->is_copy()) { | |
2885 // do not examine phi if degraded to a copy | |
2886 phi_reg = phi_base->region(); | |
2887 phi_len = phi_base->req(); | |
2888 // see if the phi is unfinished | |
2889 for (uint i = 1; i < phi_len; i++) { | |
2890 if (phi_base->in(i) == NULL) { | |
2891 // incomplete phi; do not look at it yet! | |
2892 phi_reg = NULL; | |
2893 phi_len = (uint)-1; | |
2894 break; | |
2895 } | |
2896 } | |
2897 } | |
2898 | |
2899 // Note: We do not call verify_sparse on entry, because inputs | |
2900 // can normalize to the base_memory via subsume_node or similar | |
2901 // mechanisms. This method repairs that damage. | |
2902 | |
2903 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels"); | |
2904 | |
2905 // Look at each slice. | |
2906 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { | |
2907 Node* old_in = in(i); | |
2908 // calculate the old memory value | |
2909 Node* old_mem = old_in; | |
2910 if (old_mem == empty_mem) old_mem = old_base; | |
2911 assert(old_mem == memory_at(i), ""); | |
2912 | |
2913 // maybe update (reslice) the old memory value | |
2914 | |
2915 // simplify stacked MergeMems | |
2916 Node* new_mem = old_mem; | |
2917 MergeMemNode* old_mmem; | |
2918 if (old_mem != NULL && old_mem->is_MergeMem()) | |
2919 old_mmem = old_mem->as_MergeMem(); | |
2920 else | |
2921 old_mmem = NULL; | |
2922 if (old_mmem == this) { | |
2923 // This can happen if loops break up and safepoints disappear. | |
2924 // A merge of BotPtr (default) with a RawPtr memory derived from a | |
2925 // safepoint can be rewritten to a merge of the same BotPtr with | |
2926 // the BotPtr phi coming into the loop. If that phi disappears | |
2927 // also, we can end up with a self-loop of the mergemem. | |
2928 // In general, if loops degenerate and memory effects disappear, | |
2929 // a mergemem can be left looking at itself. This simply means | |
2930 // that the mergemem's default should be used, since there is | |
2931 // no longer any apparent effect on this slice. | |
2932 // Note: If a memory slice is a MergeMem cycle, it is unreachable | |
2933 // from start. Update the input to TOP. | |
2934 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base; | |
2935 } | |
2936 else if (old_mmem != NULL) { | |
2937 new_mem = old_mmem->memory_at(i); | |
2938 } | |
2939 // else preceeding memory was not a MergeMem | |
2940 | |
2941 // replace equivalent phis (unfortunately, they do not GVN together) | |
2942 if (new_mem != NULL && new_mem != new_base && | |
2943 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) { | |
2944 if (new_mem->is_Phi()) { | |
2945 PhiNode* phi_mem = new_mem->as_Phi(); | |
2946 for (uint i = 1; i < phi_len; i++) { | |
2947 if (phi_base->in(i) != phi_mem->in(i)) { | |
2948 phi_mem = NULL; | |
2949 break; | |
2950 } | |
2951 } | |
2952 if (phi_mem != NULL) { | |
2953 // equivalent phi nodes; revert to the def | |
2954 new_mem = new_base; | |
2955 } | |
2956 } | |
2957 } | |
2958 | |
2959 // maybe store down a new value | |
2960 Node* new_in = new_mem; | |
2961 if (new_in == new_base) new_in = empty_mem; | |
2962 | |
2963 if (new_in != old_in) { | |
2964 // Warning: Do not combine this "if" with the previous "if" | |
2965 // A memory slice might have be be rewritten even if it is semantically | |
2966 // unchanged, if the base_memory value has changed. | |
2967 set_req(i, new_in); | |
2968 progress = this; // Report progress | |
2969 } | |
2970 } | |
2971 | |
2972 if (new_base != old_base) { | |
2973 set_req(Compile::AliasIdxBot, new_base); | |
2974 // Don't use set_base_memory(new_base), because we need to update du. | |
2975 assert(base_memory() == new_base, ""); | |
2976 progress = this; | |
2977 } | |
2978 | |
2979 if( base_memory() == this ) { | |
2980 // a self cycle indicates this memory path is dead | |
2981 set_req(Compile::AliasIdxBot, empty_mem); | |
2982 } | |
2983 | |
2984 // Resolve external cycles by calling Ideal on a MergeMem base_memory | |
2985 // Recursion must occur after the self cycle check above | |
2986 if( base_memory()->is_MergeMem() ) { | |
2987 MergeMemNode *new_mbase = base_memory()->as_MergeMem(); | |
2988 Node *m = phase->transform(new_mbase); // Rollup any cycles | |
2989 if( m != NULL && (m->is_top() || | |
2990 m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem) ) { | |
2991 // propagate rollup of dead cycle to self | |
2992 set_req(Compile::AliasIdxBot, empty_mem); | |
2993 } | |
2994 } | |
2995 | |
2996 if( base_memory() == empty_mem ) { | |
2997 progress = this; | |
2998 // Cut inputs during Parse phase only. | |
2999 // During Optimize phase a dead MergeMem node will be subsumed by Top. | |
3000 if( !can_reshape ) { | |
3001 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { | |
3002 if( in(i) != empty_mem ) { set_req(i, empty_mem); } | |
3003 } | |
3004 } | |
3005 } | |
3006 | |
3007 if( !progress && base_memory()->is_Phi() && can_reshape ) { | |
3008 // Check if PhiNode::Ideal's "Split phis through memory merges" | |
3009 // transform should be attempted. Look for this->phi->this cycle. | |
3010 uint merge_width = req(); | |
3011 if (merge_width > Compile::AliasIdxRaw) { | |
3012 PhiNode* phi = base_memory()->as_Phi(); | |
3013 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in | |
3014 if (phi->in(i) == this) { | |
3015 phase->is_IterGVN()->_worklist.push(phi); | |
3016 break; | |
3017 } | |
3018 } | |
3019 } | |
3020 } | |
3021 | |
3022 assert(verify_sparse(), "please, no dups of base"); | |
3023 return progress; | |
3024 } | |
3025 | |
3026 //-------------------------set_base_memory------------------------------------- | |
3027 void MergeMemNode::set_base_memory(Node *new_base) { | |
3028 Node* empty_mem = empty_memory(); | |
3029 set_req(Compile::AliasIdxBot, new_base); | |
3030 assert(memory_at(req()) == new_base, "must set default memory"); | |
3031 // Clear out other occurrences of new_base: | |
3032 if (new_base != empty_mem) { | |
3033 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { | |
3034 if (in(i) == new_base) set_req(i, empty_mem); | |
3035 } | |
3036 } | |
3037 } | |
3038 | |
3039 //------------------------------out_RegMask------------------------------------ | |
3040 const RegMask &MergeMemNode::out_RegMask() const { | |
3041 return RegMask::Empty; | |
3042 } | |
3043 | |
3044 //------------------------------dump_spec-------------------------------------- | |
3045 #ifndef PRODUCT | |
3046 void MergeMemNode::dump_spec(outputStream *st) const { | |
3047 st->print(" {"); | |
3048 Node* base_mem = base_memory(); | |
3049 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) { | |
3050 Node* mem = memory_at(i); | |
3051 if (mem == base_mem) { st->print(" -"); continue; } | |
3052 st->print( " N%d:", mem->_idx ); | |
3053 Compile::current()->get_adr_type(i)->dump_on(st); | |
3054 } | |
3055 st->print(" }"); | |
3056 } | |
3057 #endif // !PRODUCT | |
3058 | |
3059 | |
3060 #ifdef ASSERT | |
3061 static bool might_be_same(Node* a, Node* b) { | |
3062 if (a == b) return true; | |
3063 if (!(a->is_Phi() || b->is_Phi())) return false; | |
3064 // phis shift around during optimization | |
3065 return true; // pretty stupid... | |
3066 } | |
3067 | |
3068 // verify a narrow slice (either incoming or outgoing) | |
3069 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) { | |
3070 if (!VerifyAliases) return; // don't bother to verify unless requested | |
3071 if (is_error_reported()) return; // muzzle asserts when debugging an error | |
3072 if (Node::in_dump()) return; // muzzle asserts when printing | |
3073 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel"); | |
3074 assert(n != NULL, ""); | |
3075 // Elide intervening MergeMem's | |
3076 while (n->is_MergeMem()) { | |
3077 n = n->as_MergeMem()->memory_at(alias_idx); | |
3078 } | |
3079 Compile* C = Compile::current(); | |
3080 const TypePtr* n_adr_type = n->adr_type(); | |
3081 if (n == m->empty_memory()) { | |
3082 // Implicit copy of base_memory() | |
3083 } else if (n_adr_type != TypePtr::BOTTOM) { | |
3084 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type"); | |
3085 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice"); | |
3086 } else { | |
3087 // A few places like make_runtime_call "know" that VM calls are narrow, | |
3088 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM. | |
3089 bool expected_wide_mem = false; | |
3090 if (n == m->base_memory()) { | |
3091 expected_wide_mem = true; | |
3092 } else if (alias_idx == Compile::AliasIdxRaw || | |
3093 n == m->memory_at(Compile::AliasIdxRaw)) { | |
3094 expected_wide_mem = true; | |
3095 } else if (!C->alias_type(alias_idx)->is_rewritable()) { | |
3096 // memory can "leak through" calls on channels that | |
3097 // are write-once. Allow this also. | |
3098 expected_wide_mem = true; | |
3099 } | |
3100 assert(expected_wide_mem, "expected narrow slice replacement"); | |
3101 } | |
3102 } | |
3103 #else // !ASSERT | |
3104 #define verify_memory_slice(m,i,n) (0) // PRODUCT version is no-op | |
3105 #endif | |
3106 | |
3107 | |
3108 //-----------------------------memory_at--------------------------------------- | |
3109 Node* MergeMemNode::memory_at(uint alias_idx) const { | |
3110 assert(alias_idx >= Compile::AliasIdxRaw || | |
3111 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0, | |
3112 "must avoid base_memory and AliasIdxTop"); | |
3113 | |
3114 // Otherwise, it is a narrow slice. | |
3115 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory(); | |
3116 Compile *C = Compile::current(); | |
3117 if (is_empty_memory(n)) { | |
3118 // the array is sparse; empty slots are the "top" node | |
3119 n = base_memory(); | |
3120 assert(Node::in_dump() | |
3121 || n == NULL || n->bottom_type() == Type::TOP | |
3122 || n->adr_type() == TypePtr::BOTTOM | |
3123 || n->adr_type() == TypeRawPtr::BOTTOM | |
3124 || Compile::current()->AliasLevel() == 0, | |
3125 "must be a wide memory"); | |
3126 // AliasLevel == 0 if we are organizing the memory states manually. | |
3127 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM. | |
3128 } else { | |
3129 // make sure the stored slice is sane | |
3130 #ifdef ASSERT | |
3131 if (is_error_reported() || Node::in_dump()) { | |
3132 } else if (might_be_same(n, base_memory())) { | |
3133 // Give it a pass: It is a mostly harmless repetition of the base. | |
3134 // This can arise normally from node subsumption during optimization. | |
3135 } else { | |
3136 verify_memory_slice(this, alias_idx, n); | |
3137 } | |
3138 #endif | |
3139 } | |
3140 return n; | |
3141 } | |
3142 | |
3143 //---------------------------set_memory_at------------------------------------- | |
3144 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) { | |
3145 verify_memory_slice(this, alias_idx, n); | |
3146 Node* empty_mem = empty_memory(); | |
3147 if (n == base_memory()) n = empty_mem; // collapse default | |
3148 uint need_req = alias_idx+1; | |
3149 if (req() < need_req) { | |
3150 if (n == empty_mem) return; // already the default, so do not grow me | |
3151 // grow the sparse array | |
3152 do { | |
3153 add_req(empty_mem); | |
3154 } while (req() < need_req); | |
3155 } | |
3156 set_req( alias_idx, n ); | |
3157 } | |
3158 | |
3159 | |
3160 | |
3161 //--------------------------iteration_setup------------------------------------ | |
3162 void MergeMemNode::iteration_setup(const MergeMemNode* other) { | |
3163 if (other != NULL) { | |
3164 grow_to_match(other); | |
3165 // invariant: the finite support of mm2 is within mm->req() | |
3166 #ifdef ASSERT | |
3167 for (uint i = req(); i < other->req(); i++) { | |
3168 assert(other->is_empty_memory(other->in(i)), "slice left uncovered"); | |
3169 } | |
3170 #endif | |
3171 } | |
3172 // Replace spurious copies of base_memory by top. | |
3173 Node* base_mem = base_memory(); | |
3174 if (base_mem != NULL && !base_mem->is_top()) { | |
3175 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) { | |
3176 if (in(i) == base_mem) | |
3177 set_req(i, empty_memory()); | |
3178 } | |
3179 } | |
3180 } | |
3181 | |
3182 //---------------------------grow_to_match------------------------------------- | |
3183 void MergeMemNode::grow_to_match(const MergeMemNode* other) { | |
3184 Node* empty_mem = empty_memory(); | |
3185 assert(other->is_empty_memory(empty_mem), "consistent sentinels"); | |
3186 // look for the finite support of the other memory | |
3187 for (uint i = other->req(); --i >= req(); ) { | |
3188 if (other->in(i) != empty_mem) { | |
3189 uint new_len = i+1; | |
3190 while (req() < new_len) add_req(empty_mem); | |
3191 break; | |
3192 } | |
3193 } | |
3194 } | |
3195 | |
3196 //---------------------------verify_sparse------------------------------------- | |
3197 #ifndef PRODUCT | |
3198 bool MergeMemNode::verify_sparse() const { | |
3199 assert(is_empty_memory(make_empty_memory()), "sane sentinel"); | |
3200 Node* base_mem = base_memory(); | |
3201 // The following can happen in degenerate cases, since empty==top. | |
3202 if (is_empty_memory(base_mem)) return true; | |
3203 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { | |
3204 assert(in(i) != NULL, "sane slice"); | |
3205 if (in(i) == base_mem) return false; // should have been the sentinel value! | |
3206 } | |
3207 return true; | |
3208 } | |
3209 | |
3210 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) { | |
3211 Node* n; | |
3212 n = mm->in(idx); | |
3213 if (mem == n) return true; // might be empty_memory() | |
3214 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx); | |
3215 if (mem == n) return true; | |
3216 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) { | |
3217 if (mem == n) return true; | |
3218 if (n == NULL) break; | |
3219 } | |
3220 return false; | |
3221 } | |
3222 #endif // !PRODUCT |