1 /*
2 * Copyright (c) 1997, 2010, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/systemDictionary.hpp"
27 #include "compiler/compileLog.hpp"
28 #include "memory/allocation.inline.hpp"
29 #include "oops/objArrayKlass.hpp"
30 #include "opto/addnode.hpp"
31 #include "opto/cfgnode.hpp"
32 #include "opto/compile.hpp"
33 #include "opto/connode.hpp"
34 #include "opto/loopnode.hpp"
35 #include "opto/machnode.hpp"
36 #include "opto/matcher.hpp"
37 #include "opto/memnode.hpp"
38 #include "opto/mulnode.hpp"
39 #include "opto/phaseX.hpp"
40 #include "opto/regmask.hpp"
41
42 // Portions of code courtesy of Clifford Click
43
44 // Optimization - Graph Style
45
46 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st);
47
48 //=============================================================================
49 uint MemNode::size_of() const { return sizeof(*this); }
50
51 const TypePtr *MemNode::adr_type() const {
52 Node* adr = in(Address);
53 const TypePtr* cross_check = NULL;
54 DEBUG_ONLY(cross_check = _adr_type);
55 return calculate_adr_type(adr->bottom_type(), cross_check);
56 }
57
58 #ifndef PRODUCT
59 void MemNode::dump_spec(outputStream *st) const {
60 if (in(Address) == NULL) return; // node is dead
61 #ifndef ASSERT
62 // fake the missing field
63 const TypePtr* _adr_type = NULL;
64 if (in(Address) != NULL)
65 _adr_type = in(Address)->bottom_type()->isa_ptr();
66 #endif
67 dump_adr_type(this, _adr_type, st);
68
69 Compile* C = Compile::current();
70 if( C->alias_type(_adr_type)->is_volatile() )
71 st->print(" Volatile!");
72 }
73
74 void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) {
75 st->print(" @");
76 if (adr_type == NULL) {
77 st->print("NULL");
78 } else {
79 adr_type->dump_on(st);
80 Compile* C = Compile::current();
81 Compile::AliasType* atp = NULL;
82 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type);
83 if (atp == NULL)
84 st->print(", idx=?\?;");
85 else if (atp->index() == Compile::AliasIdxBot)
86 st->print(", idx=Bot;");
87 else if (atp->index() == Compile::AliasIdxTop)
88 st->print(", idx=Top;");
89 else if (atp->index() == Compile::AliasIdxRaw)
90 st->print(", idx=Raw;");
91 else {
92 ciField* field = atp->field();
93 if (field) {
94 st->print(", name=");
95 field->print_name_on(st);
96 }
97 st->print(", idx=%d;", atp->index());
98 }
99 }
100 }
101
102 extern void print_alias_types();
103
104 #endif
105
106 Node *MemNode::optimize_simple_memory_chain(Node *mchain, const TypePtr *t_adr, PhaseGVN *phase) {
107 const TypeOopPtr *tinst = t_adr->isa_oopptr();
108 if (tinst == NULL || !tinst->is_known_instance_field())
109 return mchain; // don't try to optimize non-instance types
110 uint instance_id = tinst->instance_id();
111 Node *start_mem = phase->C->start()->proj_out(TypeFunc::Memory);
112 Node *prev = NULL;
113 Node *result = mchain;
114 while (prev != result) {
115 prev = result;
116 if (result == start_mem)
117 break; // hit one of our sentinels
118 // skip over a call which does not affect this memory slice
119 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {
120 Node *proj_in = result->in(0);
121 if (proj_in->is_Allocate() && proj_in->_idx == instance_id) {
122 break; // hit one of our sentinels
123 } else if (proj_in->is_Call()) {
124 CallNode *call = proj_in->as_Call();
125 if (!call->may_modify(t_adr, phase)) {
126 result = call->in(TypeFunc::Memory);
127 }
128 } else if (proj_in->is_Initialize()) {
129 AllocateNode* alloc = proj_in->as_Initialize()->allocation();
130 // Stop if this is the initialization for the object instance which
131 // which contains this memory slice, otherwise skip over it.
132 if (alloc != NULL && alloc->_idx != instance_id) {
133 result = proj_in->in(TypeFunc::Memory);
134 }
135 } else if (proj_in->is_MemBar()) {
136 result = proj_in->in(TypeFunc::Memory);
137 } else {
138 assert(false, "unexpected projection");
139 }
140 } else if (result->is_ClearArray()) {
141 if (!ClearArrayNode::step_through(&result, instance_id, phase)) {
142 // Can not bypass initialization of the instance
143 // we are looking for.
144 break;
145 }
146 // Otherwise skip it (the call updated 'result' value).
147 } else if (result->is_MergeMem()) {
148 result = step_through_mergemem(phase, result->as_MergeMem(), t_adr, NULL, tty);
149 }
150 }
151 return result;
152 }
153
154 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, PhaseGVN *phase) {
155 const TypeOopPtr *t_oop = t_adr->isa_oopptr();
156 bool is_instance = (t_oop != NULL) && t_oop->is_known_instance_field();
157 PhaseIterGVN *igvn = phase->is_IterGVN();
158 Node *result = mchain;
159 result = optimize_simple_memory_chain(result, t_adr, phase);
160 if (is_instance && igvn != NULL && result->is_Phi()) {
161 PhiNode *mphi = result->as_Phi();
162 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
163 const TypePtr *t = mphi->adr_type();
164 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
165 t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
166 t->is_oopptr()->cast_to_exactness(true)
167 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
168 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop) {
169 // clone the Phi with our address type
170 result = mphi->split_out_instance(t_adr, igvn);
171 } else {
172 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain");
173 }
174 }
175 return result;
176 }
177
178 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) {
179 uint alias_idx = phase->C->get_alias_index(tp);
180 Node *mem = mmem;
181 #ifdef ASSERT
182 {
183 // Check that current type is consistent with the alias index used during graph construction
184 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
185 bool consistent = adr_check == NULL || adr_check->empty() ||
186 phase->C->must_alias(adr_check, alias_idx );
187 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
188 if( !consistent && adr_check != NULL && !adr_check->empty() &&
189 tp->isa_aryptr() && tp->offset() == Type::OffsetBot &&
190 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot &&
191 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() ||
192 adr_check->offset() == oopDesc::klass_offset_in_bytes() ||
193 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) {
194 // don't assert if it is dead code.
195 consistent = true;
196 }
197 if( !consistent ) {
198 st->print("alias_idx==%d, adr_check==", alias_idx);
199 if( adr_check == NULL ) {
200 st->print("NULL");
201 } else {
202 adr_check->dump();
203 }
204 st->cr();
205 print_alias_types();
206 assert(consistent, "adr_check must match alias idx");
207 }
208 }
209 #endif
210 // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally
211 // means an array I have not precisely typed yet. Do not do any
212 // alias stuff with it any time soon.
213 const TypeOopPtr *toop = tp->isa_oopptr();
214 if( tp->base() != Type::AnyPtr &&
215 !(toop &&
216 toop->klass() != NULL &&
217 toop->klass()->is_java_lang_Object() &&
218 toop->offset() == Type::OffsetBot) ) {
219 // compress paths and change unreachable cycles to TOP
220 // If not, we can update the input infinitely along a MergeMem cycle
221 // Equivalent code in PhiNode::Ideal
222 Node* m = phase->transform(mmem);
223 // If transformed to a MergeMem, get the desired slice
224 // Otherwise the returned node represents memory for every slice
225 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
226 // Update input if it is progress over what we have now
227 }
228 return mem;
229 }
230
231 //--------------------------Ideal_common---------------------------------------
232 // Look for degenerate control and memory inputs. Bypass MergeMem inputs.
233 // Unhook non-raw memories from complete (macro-expanded) initializations.
234 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
235 // If our control input is a dead region, kill all below the region
236 Node *ctl = in(MemNode::Control);
237 if (ctl && remove_dead_region(phase, can_reshape))
238 return this;
239 ctl = in(MemNode::Control);
240 // Don't bother trying to transform a dead node
241 if( ctl && ctl->is_top() ) return NodeSentinel;
242
243 PhaseIterGVN *igvn = phase->is_IterGVN();
244 // Wait if control on the worklist.
245 if (ctl && can_reshape && igvn != NULL) {
246 Node* bol = NULL;
247 Node* cmp = NULL;
248 if (ctl->in(0)->is_If()) {
249 assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity");
250 bol = ctl->in(0)->in(1);
251 if (bol->is_Bool())
252 cmp = ctl->in(0)->in(1)->in(1);
253 }
254 if (igvn->_worklist.member(ctl) ||
255 (bol != NULL && igvn->_worklist.member(bol)) ||
256 (cmp != NULL && igvn->_worklist.member(cmp)) ) {
257 // This control path may be dead.
258 // Delay this memory node transformation until the control is processed.
259 phase->is_IterGVN()->_worklist.push(this);
260 return NodeSentinel; // caller will return NULL
261 }
262 }
263 // Ignore if memory is dead, or self-loop
264 Node *mem = in(MemNode::Memory);
265 if( phase->type( mem ) == Type::TOP ) return NodeSentinel; // caller will return NULL
266 assert( mem != this, "dead loop in MemNode::Ideal" );
267
268 Node *address = in(MemNode::Address);
269 const Type *t_adr = phase->type( address );
270 if( t_adr == Type::TOP ) return NodeSentinel; // caller will return NULL
271
272 if( can_reshape && igvn != NULL &&
273 (igvn->_worklist.member(address) ||
274 igvn->_worklist.size() > 0 && (phase->type(address) != adr_type())) ) {
275 // The address's base and type may change when the address is processed.
276 // Delay this mem node transformation until the address is processed.
277 phase->is_IterGVN()->_worklist.push(this);
278 return NodeSentinel; // caller will return NULL
279 }
280
281 // Do NOT remove or optimize the next lines: ensure a new alias index
282 // is allocated for an oop pointer type before Escape Analysis.
283 // Note: C++ will not remove it since the call has side effect.
284 if ( t_adr->isa_oopptr() ) {
285 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr());
286 }
287
288 #ifdef ASSERT
289 Node* base = NULL;
290 if (address->is_AddP())
291 base = address->in(AddPNode::Base);
292 assert(base == NULL || t_adr->isa_rawptr() ||
293 !phase->type(base)->higher_equal(TypePtr::NULL_PTR), "NULL+offs not RAW address?");
294 #endif
295
296 // Avoid independent memory operations
297 Node* old_mem = mem;
298
299 // The code which unhooks non-raw memories from complete (macro-expanded)
300 // initializations was removed. After macro-expansion all stores catched
301 // by Initialize node became raw stores and there is no information
302 // which memory slices they modify. So it is unsafe to move any memory
303 // operation above these stores. Also in most cases hooked non-raw memories
304 // were already unhooked by using information from detect_ptr_independence()
305 // and find_previous_store().
306
307 if (mem->is_MergeMem()) {
308 MergeMemNode* mmem = mem->as_MergeMem();
309 const TypePtr *tp = t_adr->is_ptr();
310
311 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
312 }
313
314 if (mem != old_mem) {
315 set_req(MemNode::Memory, mem);
316 if (phase->type( mem ) == Type::TOP) return NodeSentinel;
317 return this;
318 }
319
320 // let the subclass continue analyzing...
321 return NULL;
322 }
323
324 // Helper function for proving some simple control dominations.
325 // Attempt to prove that all control inputs of 'dom' dominate 'sub'.
326 // Already assumes that 'dom' is available at 'sub', and that 'sub'
327 // is not a constant (dominated by the method's StartNode).
328 // Used by MemNode::find_previous_store to prove that the
329 // control input of a memory operation predates (dominates)
330 // an allocation it wants to look past.
331 bool MemNode::all_controls_dominate(Node* dom, Node* sub) {
332 if (dom == NULL || dom->is_top() || sub == NULL || sub->is_top())
333 return false; // Conservative answer for dead code
334
335 // Check 'dom'. Skip Proj and CatchProj nodes.
336 dom = dom->find_exact_control(dom);
337 if (dom == NULL || dom->is_top())
338 return false; // Conservative answer for dead code
339
340 if (dom == sub) {
341 // For the case when, for example, 'sub' is Initialize and the original
342 // 'dom' is Proj node of the 'sub'.
343 return false;
344 }
345
346 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub)
347 return true;
348
349 // 'dom' dominates 'sub' if its control edge and control edges
350 // of all its inputs dominate or equal to sub's control edge.
351
352 // Currently 'sub' is either Allocate, Initialize or Start nodes.
353 // Or Region for the check in LoadNode::Ideal();
354 // 'sub' should have sub->in(0) != NULL.
355 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() ||
356 sub->is_Region(), "expecting only these nodes");
357
358 // Get control edge of 'sub'.
359 Node* orig_sub = sub;
360 sub = sub->find_exact_control(sub->in(0));
361 if (sub == NULL || sub->is_top())
362 return false; // Conservative answer for dead code
363
364 assert(sub->is_CFG(), "expecting control");
365
366 if (sub == dom)
367 return true;
368
369 if (sub->is_Start() || sub->is_Root())
370 return false;
371
372 {
373 // Check all control edges of 'dom'.
374
375 ResourceMark rm;
376 Arena* arena = Thread::current()->resource_area();
377 Node_List nlist(arena);
378 Unique_Node_List dom_list(arena);
379
380 dom_list.push(dom);
381 bool only_dominating_controls = false;
382
383 for (uint next = 0; next < dom_list.size(); next++) {
384 Node* n = dom_list.at(next);
385 if (n == orig_sub)
386 return false; // One of dom's inputs dominated by sub.
387 if (!n->is_CFG() && n->pinned()) {
388 // Check only own control edge for pinned non-control nodes.
389 n = n->find_exact_control(n->in(0));
390 if (n == NULL || n->is_top())
391 return false; // Conservative answer for dead code
392 assert(n->is_CFG(), "expecting control");
393 dom_list.push(n);
394 } else if (n->is_Con() || n->is_Start() || n->is_Root()) {
395 only_dominating_controls = true;
396 } else if (n->is_CFG()) {
397 if (n->dominates(sub, nlist))
398 only_dominating_controls = true;
399 else
400 return false;
401 } else {
402 // First, own control edge.
403 Node* m = n->find_exact_control(n->in(0));
404 if (m != NULL) {
405 if (m->is_top())
406 return false; // Conservative answer for dead code
407 dom_list.push(m);
408 }
409 // Now, the rest of edges.
410 uint cnt = n->req();
411 for (uint i = 1; i < cnt; i++) {
412 m = n->find_exact_control(n->in(i));
413 if (m == NULL || m->is_top())
414 continue;
415 dom_list.push(m);
416 }
417 }
418 }
419 return only_dominating_controls;
420 }
421 }
422
423 //---------------------detect_ptr_independence---------------------------------
424 // Used by MemNode::find_previous_store to prove that two base
425 // pointers are never equal.
426 // The pointers are accompanied by their associated allocations,
427 // if any, which have been previously discovered by the caller.
428 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
429 Node* p2, AllocateNode* a2,
430 PhaseTransform* phase) {
431 // Attempt to prove that these two pointers cannot be aliased.
432 // They may both manifestly be allocations, and they should differ.
433 // Or, if they are not both allocations, they can be distinct constants.
434 // Otherwise, one is an allocation and the other a pre-existing value.
435 if (a1 == NULL && a2 == NULL) { // neither an allocation
436 return (p1 != p2) && p1->is_Con() && p2->is_Con();
437 } else if (a1 != NULL && a2 != NULL) { // both allocations
438 return (a1 != a2);
439 } else if (a1 != NULL) { // one allocation a1
440 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.)
441 return all_controls_dominate(p2, a1);
442 } else { //(a2 != NULL) // one allocation a2
443 return all_controls_dominate(p1, a2);
444 }
445 return false;
446 }
447
448
449 // The logic for reordering loads and stores uses four steps:
450 // (a) Walk carefully past stores and initializations which we
451 // can prove are independent of this load.
452 // (b) Observe that the next memory state makes an exact match
453 // with self (load or store), and locate the relevant store.
454 // (c) Ensure that, if we were to wire self directly to the store,
455 // the optimizer would fold it up somehow.
456 // (d) Do the rewiring, and return, depending on some other part of
457 // the optimizer to fold up the load.
458 // This routine handles steps (a) and (b). Steps (c) and (d) are
459 // specific to loads and stores, so they are handled by the callers.
460 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.)
461 //
462 Node* MemNode::find_previous_store(PhaseTransform* phase) {
463 Node* ctrl = in(MemNode::Control);
464 Node* adr = in(MemNode::Address);
465 intptr_t offset = 0;
466 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
467 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase);
468
469 if (offset == Type::OffsetBot)
470 return NULL; // cannot unalias unless there are precise offsets
471
472 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr();
473
474 intptr_t size_in_bytes = memory_size();
475
476 Node* mem = in(MemNode::Memory); // start searching here...
477
478 int cnt = 50; // Cycle limiter
479 for (;;) { // While we can dance past unrelated stores...
480 if (--cnt < 0) break; // Caught in cycle or a complicated dance?
481
482 if (mem->is_Store()) {
483 Node* st_adr = mem->in(MemNode::Address);
484 intptr_t st_offset = 0;
485 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
486 if (st_base == NULL)
487 break; // inscrutable pointer
488 if (st_offset != offset && st_offset != Type::OffsetBot) {
489 const int MAX_STORE = BytesPerLong;
490 if (st_offset >= offset + size_in_bytes ||
491 st_offset <= offset - MAX_STORE ||
492 st_offset <= offset - mem->as_Store()->memory_size()) {
493 // Success: The offsets are provably independent.
494 // (You may ask, why not just test st_offset != offset and be done?
495 // The answer is that stores of different sizes can co-exist
496 // in the same sequence of RawMem effects. We sometimes initialize
497 // a whole 'tile' of array elements with a single jint or jlong.)
498 mem = mem->in(MemNode::Memory);
499 continue; // (a) advance through independent store memory
500 }
501 }
502 if (st_base != base &&
503 detect_ptr_independence(base, alloc,
504 st_base,
505 AllocateNode::Ideal_allocation(st_base, phase),
506 phase)) {
507 // Success: The bases are provably independent.
508 mem = mem->in(MemNode::Memory);
509 continue; // (a) advance through independent store memory
510 }
511
512 // (b) At this point, if the bases or offsets do not agree, we lose,
513 // since we have not managed to prove 'this' and 'mem' independent.
514 if (st_base == base && st_offset == offset) {
515 return mem; // let caller handle steps (c), (d)
516 }
517
518 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
519 InitializeNode* st_init = mem->in(0)->as_Initialize();
520 AllocateNode* st_alloc = st_init->allocation();
521 if (st_alloc == NULL)
522 break; // something degenerated
523 bool known_identical = false;
524 bool known_independent = false;
525 if (alloc == st_alloc)
526 known_identical = true;
527 else if (alloc != NULL)
528 known_independent = true;
529 else if (all_controls_dominate(this, st_alloc))
530 known_independent = true;
531
532 if (known_independent) {
533 // The bases are provably independent: Either they are
534 // manifestly distinct allocations, or else the control
535 // of this load dominates the store's allocation.
536 int alias_idx = phase->C->get_alias_index(adr_type());
537 if (alias_idx == Compile::AliasIdxRaw) {
538 mem = st_alloc->in(TypeFunc::Memory);
539 } else {
540 mem = st_init->memory(alias_idx);
541 }
542 continue; // (a) advance through independent store memory
543 }
544
545 // (b) at this point, if we are not looking at a store initializing
546 // the same allocation we are loading from, we lose.
547 if (known_identical) {
548 // From caller, can_see_stored_value will consult find_captured_store.
549 return mem; // let caller handle steps (c), (d)
550 }
551
552 } else if (addr_t != NULL && addr_t->is_known_instance_field()) {
553 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
554 if (mem->is_Proj() && mem->in(0)->is_Call()) {
555 CallNode *call = mem->in(0)->as_Call();
556 if (!call->may_modify(addr_t, phase)) {
557 mem = call->in(TypeFunc::Memory);
558 continue; // (a) advance through independent call memory
559 }
560 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) {
561 mem = mem->in(0)->in(TypeFunc::Memory);
562 continue; // (a) advance through independent MemBar memory
563 } else if (mem->is_ClearArray()) {
564 if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) {
565 // (the call updated 'mem' value)
566 continue; // (a) advance through independent allocation memory
567 } else {
568 // Can not bypass initialization of the instance
569 // we are looking for.
570 return mem;
571 }
572 } else if (mem->is_MergeMem()) {
573 int alias_idx = phase->C->get_alias_index(adr_type());
574 mem = mem->as_MergeMem()->memory_at(alias_idx);
575 continue; // (a) advance through independent MergeMem memory
576 }
577 }
578
579 // Unless there is an explicit 'continue', we must bail out here,
580 // because 'mem' is an inscrutable memory state (e.g., a call).
581 break;
582 }
583
584 return NULL; // bail out
585 }
586
587 //----------------------calculate_adr_type-------------------------------------
588 // Helper function. Notices when the given type of address hits top or bottom.
589 // Also, asserts a cross-check of the type against the expected address type.
590 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
591 if (t == Type::TOP) return NULL; // does not touch memory any more?
592 #ifdef PRODUCT
593 cross_check = NULL;
594 #else
595 if (!VerifyAliases || is_error_reported() || Node::in_dump()) cross_check = NULL;
596 #endif
597 const TypePtr* tp = t->isa_ptr();
598 if (tp == NULL) {
599 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
600 return TypePtr::BOTTOM; // touches lots of memory
601 } else {
602 #ifdef ASSERT
603 // %%%% [phh] We don't check the alias index if cross_check is
604 // TypeRawPtr::BOTTOM. Needs to be investigated.
605 if (cross_check != NULL &&
606 cross_check != TypePtr::BOTTOM &&
607 cross_check != TypeRawPtr::BOTTOM) {
608 // Recheck the alias index, to see if it has changed (due to a bug).
609 Compile* C = Compile::current();
610 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
611 "must stay in the original alias category");
612 // The type of the address must be contained in the adr_type,
613 // disregarding "null"-ness.
614 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
615 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
616 assert(cross_check->meet(tp_notnull) == cross_check,
617 "real address must not escape from expected memory type");
618 }
619 #endif
620 return tp;
621 }
622 }
623
624 //------------------------adr_phi_is_loop_invariant----------------------------
625 // A helper function for Ideal_DU_postCCP to check if a Phi in a counted
626 // loop is loop invariant. Make a quick traversal of Phi and associated
627 // CastPP nodes, looking to see if they are a closed group within the loop.
628 bool MemNode::adr_phi_is_loop_invariant(Node* adr_phi, Node* cast) {
629 // The idea is that the phi-nest must boil down to only CastPP nodes
630 // with the same data. This implies that any path into the loop already
631 // includes such a CastPP, and so the original cast, whatever its input,
632 // must be covered by an equivalent cast, with an earlier control input.
633 ResourceMark rm;
634
635 // The loop entry input of the phi should be the unique dominating
636 // node for every Phi/CastPP in the loop.
637 Unique_Node_List closure;
638 closure.push(adr_phi->in(LoopNode::EntryControl));
639
640 // Add the phi node and the cast to the worklist.
641 Unique_Node_List worklist;
642 worklist.push(adr_phi);
643 if( cast != NULL ){
644 if( !cast->is_ConstraintCast() ) return false;
645 worklist.push(cast);
646 }
647
648 // Begin recursive walk of phi nodes.
649 while( worklist.size() ){
650 // Take a node off the worklist
651 Node *n = worklist.pop();
652 if( !closure.member(n) ){
653 // Add it to the closure.
654 closure.push(n);
655 // Make a sanity check to ensure we don't waste too much time here.
656 if( closure.size() > 20) return false;
657 // This node is OK if:
658 // - it is a cast of an identical value
659 // - or it is a phi node (then we add its inputs to the worklist)
660 // Otherwise, the node is not OK, and we presume the cast is not invariant
661 if( n->is_ConstraintCast() ){
662 worklist.push(n->in(1));
663 } else if( n->is_Phi() ) {
664 for( uint i = 1; i < n->req(); i++ ) {
665 worklist.push(n->in(i));
666 }
667 } else {
668 return false;
669 }
670 }
671 }
672
673 // Quit when the worklist is empty, and we've found no offending nodes.
674 return true;
675 }
676
677 //------------------------------Ideal_DU_postCCP-------------------------------
678 // Find any cast-away of null-ness and keep its control. Null cast-aways are
679 // going away in this pass and we need to make this memory op depend on the
680 // gating null check.
681 Node *MemNode::Ideal_DU_postCCP( PhaseCCP *ccp ) {
682 return Ideal_common_DU_postCCP(ccp, this, in(MemNode::Address));
683 }
684
685 // I tried to leave the CastPP's in. This makes the graph more accurate in
686 // some sense; we get to keep around the knowledge that an oop is not-null
687 // after some test. Alas, the CastPP's interfere with GVN (some values are
688 // the regular oop, some are the CastPP of the oop, all merge at Phi's which
689 // cannot collapse, etc). This cost us 10% on SpecJVM, even when I removed
690 // some of the more trivial cases in the optimizer. Removing more useless
691 // Phi's started allowing Loads to illegally float above null checks. I gave
692 // up on this approach. CNC 10/20/2000
693 // This static method may be called not from MemNode (EncodePNode calls it).
694 // Only the control edge of the node 'n' might be updated.
695 Node *MemNode::Ideal_common_DU_postCCP( PhaseCCP *ccp, Node* n, Node* adr ) {
696 Node *skipped_cast = NULL;
697 // Need a null check? Regular static accesses do not because they are
698 // from constant addresses. Array ops are gated by the range check (which
699 // always includes a NULL check). Just check field ops.
700 if( n->in(MemNode::Control) == NULL ) {
701 // Scan upwards for the highest location we can place this memory op.
702 while( true ) {
703 switch( adr->Opcode() ) {
704
705 case Op_AddP: // No change to NULL-ness, so peek thru AddP's
706 adr = adr->in(AddPNode::Base);
707 continue;
708
709 case Op_DecodeN: // No change to NULL-ness, so peek thru
710 adr = adr->in(1);
711 continue;
712
713 case Op_CastPP:
714 // If the CastPP is useless, just peek on through it.
715 if( ccp->type(adr) == ccp->type(adr->in(1)) ) {
716 // Remember the cast that we've peeked though. If we peek
717 // through more than one, then we end up remembering the highest
718 // one, that is, if in a loop, the one closest to the top.
719 skipped_cast = adr;
720 adr = adr->in(1);
721 continue;
722 }
723 // CastPP is going away in this pass! We need this memory op to be
724 // control-dependent on the test that is guarding the CastPP.
725 ccp->hash_delete(n);
726 n->set_req(MemNode::Control, adr->in(0));
727 ccp->hash_insert(n);
728 return n;
729
730 case Op_Phi:
731 // Attempt to float above a Phi to some dominating point.
732 if (adr->in(0) != NULL && adr->in(0)->is_CountedLoop()) {
733 // If we've already peeked through a Cast (which could have set the
734 // control), we can't float above a Phi, because the skipped Cast
735 // may not be loop invariant.
736 if (adr_phi_is_loop_invariant(adr, skipped_cast)) {
737 adr = adr->in(1);
738 continue;
739 }
740 }
741
742 // Intentional fallthrough!
743
744 // No obvious dominating point. The mem op is pinned below the Phi
745 // by the Phi itself. If the Phi goes away (no true value is merged)
746 // then the mem op can float, but not indefinitely. It must be pinned
747 // behind the controls leading to the Phi.
748 case Op_CheckCastPP:
749 // These usually stick around to change address type, however a
750 // useless one can be elided and we still need to pick up a control edge
751 if (adr->in(0) == NULL) {
752 // This CheckCastPP node has NO control and is likely useless. But we
753 // need check further up the ancestor chain for a control input to keep
754 // the node in place. 4959717.
755 skipped_cast = adr;
756 adr = adr->in(1);
757 continue;
758 }
759 ccp->hash_delete(n);
760 n->set_req(MemNode::Control, adr->in(0));
761 ccp->hash_insert(n);
762 return n;
763
764 // List of "safe" opcodes; those that implicitly block the memory
765 // op below any null check.
766 case Op_CastX2P: // no null checks on native pointers
767 case Op_Parm: // 'this' pointer is not null
768 case Op_LoadP: // Loading from within a klass
769 case Op_LoadN: // Loading from within a klass
770 case Op_LoadKlass: // Loading from within a klass
771 case Op_LoadNKlass: // Loading from within a klass
772 case Op_ConP: // Loading from a klass
773 case Op_ConN: // Loading from a klass
774 case Op_CreateEx: // Sucking up the guts of an exception oop
775 case Op_Con: // Reading from TLS
776 case Op_CMoveP: // CMoveP is pinned
777 case Op_CMoveN: // CMoveN is pinned
778 break; // No progress
779
780 case Op_Proj: // Direct call to an allocation routine
781 case Op_SCMemProj: // Memory state from store conditional ops
782 #ifdef ASSERT
783 {
784 assert(adr->as_Proj()->_con == TypeFunc::Parms, "must be return value");
785 const Node* call = adr->in(0);
786 if (call->is_CallJava()) {
787 const CallJavaNode* call_java = call->as_CallJava();
788 const TypeTuple *r = call_java->tf()->range();
789 assert(r->cnt() > TypeFunc::Parms, "must return value");
790 const Type* ret_type = r->field_at(TypeFunc::Parms);
791 assert(ret_type && ret_type->isa_ptr(), "must return pointer");
792 // We further presume that this is one of
793 // new_instance_Java, new_array_Java, or
794 // the like, but do not assert for this.
795 } else if (call->is_Allocate()) {
796 // similar case to new_instance_Java, etc.
797 } else if (!call->is_CallLeaf()) {
798 // Projections from fetch_oop (OSR) are allowed as well.
799 ShouldNotReachHere();
800 }
801 }
802 #endif
803 break;
804 default:
805 ShouldNotReachHere();
806 }
807 break;
808 }
809 }
810
811 return NULL; // No progress
812 }
813
814
815 //=============================================================================
816 uint LoadNode::size_of() const { return sizeof(*this); }
817 uint LoadNode::cmp( const Node &n ) const
818 { return !Type::cmp( _type, ((LoadNode&)n)._type ); }
819 const Type *LoadNode::bottom_type() const { return _type; }
820 uint LoadNode::ideal_reg() const {
821 return Matcher::base2reg[_type->base()];
822 }
823
824 #ifndef PRODUCT
825 void LoadNode::dump_spec(outputStream *st) const {
826 MemNode::dump_spec(st);
827 if( !Verbose && !WizardMode ) {
828 // standard dump does this in Verbose and WizardMode
829 st->print(" #"); _type->dump_on(st);
830 }
831 }
832 #endif
833
834 #ifdef ASSERT
835 //----------------------------is_immutable_value-------------------------------
836 // Helper function to allow a raw load without control edge for some cases
837 bool LoadNode::is_immutable_value(Node* adr) {
838 return (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() &&
839 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal &&
840 (adr->in(AddPNode::Offset)->find_intptr_t_con(-1) ==
841 in_bytes(JavaThread::osthread_offset())));
842 }
843 #endif
844
845 //----------------------------LoadNode::make-----------------------------------
846 // Polymorphic factory method:
847 Node *LoadNode::make( PhaseGVN& gvn, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt ) {
848 Compile* C = gvn.C;
849
850 // sanity check the alias category against the created node type
851 assert(!(adr_type->isa_oopptr() &&
852 adr_type->offset() == oopDesc::klass_offset_in_bytes()),
853 "use LoadKlassNode instead");
854 assert(!(adr_type->isa_aryptr() &&
855 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
856 "use LoadRangeNode instead");
857 // Check control edge of raw loads
858 assert( ctl != NULL || C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
859 // oop will be recorded in oop map if load crosses safepoint
860 rt->isa_oopptr() || is_immutable_value(adr),
861 "raw memory operations should have control edge");
862 switch (bt) {
863 case T_BOOLEAN: return new (C, 3) LoadUBNode(ctl, mem, adr, adr_type, rt->is_int() );
864 case T_BYTE: return new (C, 3) LoadBNode (ctl, mem, adr, adr_type, rt->is_int() );
865 case T_INT: return new (C, 3) LoadINode (ctl, mem, adr, adr_type, rt->is_int() );
866 case T_CHAR: return new (C, 3) LoadUSNode(ctl, mem, adr, adr_type, rt->is_int() );
867 case T_SHORT: return new (C, 3) LoadSNode (ctl, mem, adr, adr_type, rt->is_int() );
868 case T_LONG: return new (C, 3) LoadLNode (ctl, mem, adr, adr_type, rt->is_long() );
869 case T_FLOAT: return new (C, 3) LoadFNode (ctl, mem, adr, adr_type, rt );
870 case T_DOUBLE: return new (C, 3) LoadDNode (ctl, mem, adr, adr_type, rt );
871 case T_ADDRESS: return new (C, 3) LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr() );
872 case T_OBJECT:
873 #ifdef _LP64
874 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
875 Node* load = gvn.transform(new (C, 3) LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop()));
876 return new (C, 2) DecodeNNode(load, load->bottom_type()->make_ptr());
877 } else
878 #endif
879 {
880 assert(!adr->bottom_type()->is_ptr_to_narrowoop(), "should have got back a narrow oop");
881 return new (C, 3) LoadPNode(ctl, mem, adr, adr_type, rt->is_oopptr());
882 }
883 }
884 ShouldNotReachHere();
885 return (LoadNode*)NULL;
886 }
887
888 LoadLNode* LoadLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt) {
889 bool require_atomic = true;
890 return new (C, 3) LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), require_atomic);
891 }
892
893
894
895
896 //------------------------------hash-------------------------------------------
897 uint LoadNode::hash() const {
898 // unroll addition of interesting fields
899 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
900 }
901
902 //---------------------------can_see_stored_value------------------------------
903 // This routine exists to make sure this set of tests is done the same
904 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
905 // will change the graph shape in a way which makes memory alive twice at the
906 // same time (uses the Oracle model of aliasing), then some
907 // LoadXNode::Identity will fold things back to the equivalence-class model
908 // of aliasing.
909 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const {
910 Node* ld_adr = in(MemNode::Address);
911
912 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
913 Compile::AliasType* atp = tp != NULL ? phase->C->alias_type(tp) : NULL;
914 if (EliminateAutoBox && atp != NULL && atp->index() >= Compile::AliasIdxRaw &&
915 atp->field() != NULL && !atp->field()->is_volatile()) {
916 uint alias_idx = atp->index();
917 bool final = atp->field()->is_final();
918 Node* result = NULL;
919 Node* current = st;
920 // Skip through chains of MemBarNodes checking the MergeMems for
921 // new states for the slice of this load. Stop once any other
922 // kind of node is encountered. Loads from final memory can skip
923 // through any kind of MemBar but normal loads shouldn't skip
924 // through MemBarAcquire since the could allow them to move out of
925 // a synchronized region.
926 while (current->is_Proj()) {
927 int opc = current->in(0)->Opcode();
928 if ((final && opc == Op_MemBarAcquire) ||
929 opc == Op_MemBarRelease || opc == Op_MemBarCPUOrder) {
930 Node* mem = current->in(0)->in(TypeFunc::Memory);
931 if (mem->is_MergeMem()) {
932 MergeMemNode* merge = mem->as_MergeMem();
933 Node* new_st = merge->memory_at(alias_idx);
934 if (new_st == merge->base_memory()) {
935 // Keep searching
936 current = merge->base_memory();
937 continue;
938 }
939 // Save the new memory state for the slice and fall through
940 // to exit.
941 result = new_st;
942 }
943 }
944 break;
945 }
946 if (result != NULL) {
947 st = result;
948 }
949 }
950
951
952 // Loop around twice in the case Load -> Initialize -> Store.
953 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
954 for (int trip = 0; trip <= 1; trip++) {
955
956 if (st->is_Store()) {
957 Node* st_adr = st->in(MemNode::Address);
958 if (!phase->eqv(st_adr, ld_adr)) {
959 // Try harder before giving up... Match raw and non-raw pointers.
960 intptr_t st_off = 0;
961 AllocateNode* alloc = AllocateNode::Ideal_allocation(st_adr, phase, st_off);
962 if (alloc == NULL) return NULL;
963 intptr_t ld_off = 0;
964 AllocateNode* allo2 = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
965 if (alloc != allo2) return NULL;
966 if (ld_off != st_off) return NULL;
967 // At this point we have proven something like this setup:
968 // A = Allocate(...)
969 // L = LoadQ(, AddP(CastPP(, A.Parm),, #Off))
970 // S = StoreQ(, AddP(, A.Parm , #Off), V)
971 // (Actually, we haven't yet proven the Q's are the same.)
972 // In other words, we are loading from a casted version of
973 // the same pointer-and-offset that we stored to.
974 // Thus, we are able to replace L by V.
975 }
976 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
977 if (store_Opcode() != st->Opcode())
978 return NULL;
979 return st->in(MemNode::ValueIn);
980 }
981
982 intptr_t offset = 0; // scratch
983
984 // A load from a freshly-created object always returns zero.
985 // (This can happen after LoadNode::Ideal resets the load's memory input
986 // to find_captured_store, which returned InitializeNode::zero_memory.)
987 if (st->is_Proj() && st->in(0)->is_Allocate() &&
988 st->in(0) == AllocateNode::Ideal_allocation(ld_adr, phase, offset) &&
989 offset >= st->in(0)->as_Allocate()->minimum_header_size()) {
990 // return a zero value for the load's basic type
991 // (This is one of the few places where a generic PhaseTransform
992 // can create new nodes. Think of it as lazily manifesting
993 // virtually pre-existing constants.)
994 return phase->zerocon(memory_type());
995 }
996
997 // A load from an initialization barrier can match a captured store.
998 if (st->is_Proj() && st->in(0)->is_Initialize()) {
999 InitializeNode* init = st->in(0)->as_Initialize();
1000 AllocateNode* alloc = init->allocation();
1001 if (alloc != NULL &&
1002 alloc == AllocateNode::Ideal_allocation(ld_adr, phase, offset)) {
1003 // examine a captured store value
1004 st = init->find_captured_store(offset, memory_size(), phase);
1005 if (st != NULL)
1006 continue; // take one more trip around
1007 }
1008 }
1009
1010 break;
1011 }
1012
1013 return NULL;
1014 }
1015
1016 //----------------------is_instance_field_load_with_local_phi------------------
1017 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
1018 if( in(MemNode::Memory)->is_Phi() && in(MemNode::Memory)->in(0) == ctrl &&
1019 in(MemNode::Address)->is_AddP() ) {
1020 const TypeOopPtr* t_oop = in(MemNode::Address)->bottom_type()->isa_oopptr();
1021 // Only instances.
1022 if( t_oop != NULL && t_oop->is_known_instance_field() &&
1023 t_oop->offset() != Type::OffsetBot &&
1024 t_oop->offset() != Type::OffsetTop) {
1025 return true;
1026 }
1027 }
1028 return false;
1029 }
1030
1031 //------------------------------Identity---------------------------------------
1032 // Loads are identity if previous store is to same address
1033 Node *LoadNode::Identity( PhaseTransform *phase ) {
1034 // If the previous store-maker is the right kind of Store, and the store is
1035 // to the same address, then we are equal to the value stored.
1036 Node* mem = in(MemNode::Memory);
1037 Node* value = can_see_stored_value(mem, phase);
1038 if( value ) {
1039 // byte, short & char stores truncate naturally.
1040 // A load has to load the truncated value which requires
1041 // some sort of masking operation and that requires an
1042 // Ideal call instead of an Identity call.
1043 if (memory_size() < BytesPerInt) {
1044 // If the input to the store does not fit with the load's result type,
1045 // it must be truncated via an Ideal call.
1046 if (!phase->type(value)->higher_equal(phase->type(this)))
1047 return this;
1048 }
1049 // (This works even when value is a Con, but LoadNode::Value
1050 // usually runs first, producing the singleton type of the Con.)
1051 return value;
1052 }
1053
1054 // Search for an existing data phi which was generated before for the same
1055 // instance's field to avoid infinite generation of phis in a loop.
1056 Node *region = mem->in(0);
1057 if (is_instance_field_load_with_local_phi(region)) {
1058 const TypePtr *addr_t = in(MemNode::Address)->bottom_type()->isa_ptr();
1059 int this_index = phase->C->get_alias_index(addr_t);
1060 int this_offset = addr_t->offset();
1061 int this_id = addr_t->is_oopptr()->instance_id();
1062 const Type* this_type = bottom_type();
1063 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1064 Node* phi = region->fast_out(i);
1065 if (phi->is_Phi() && phi != mem &&
1066 phi->as_Phi()->is_same_inst_field(this_type, this_id, this_index, this_offset)) {
1067 return phi;
1068 }
1069 }
1070 }
1071
1072 return this;
1073 }
1074
1075
1076 // Returns true if the AliasType refers to the field that holds the
1077 // cached box array. Currently only handles the IntegerCache case.
1078 static bool is_autobox_cache(Compile::AliasType* atp) {
1079 if (atp != NULL && atp->field() != NULL) {
1080 ciField* field = atp->field();
1081 ciSymbol* klass = field->holder()->name();
1082 if (field->name() == ciSymbol::cache_field_name() &&
1083 field->holder()->uses_default_loader() &&
1084 klass == ciSymbol::java_lang_Integer_IntegerCache()) {
1085 return true;
1086 }
1087 }
1088 return false;
1089 }
1090
1091 // Fetch the base value in the autobox array
1092 static bool fetch_autobox_base(Compile::AliasType* atp, int& cache_offset) {
1093 if (atp != NULL && atp->field() != NULL) {
1094 ciField* field = atp->field();
1095 ciSymbol* klass = field->holder()->name();
1096 if (field->name() == ciSymbol::cache_field_name() &&
1097 field->holder()->uses_default_loader() &&
1098 klass == ciSymbol::java_lang_Integer_IntegerCache()) {
1099 assert(field->is_constant(), "what?");
1100 ciObjArray* array = field->constant_value().as_object()->as_obj_array();
1101 // Fetch the box object at the base of the array and get its value
1102 ciInstance* box = array->obj_at(0)->as_instance();
1103 ciInstanceKlass* ik = box->klass()->as_instance_klass();
1104 if (ik->nof_nonstatic_fields() == 1) {
1105 // This should be true nonstatic_field_at requires calling
1106 // nof_nonstatic_fields so check it anyway
1107 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1108 cache_offset = c.as_int();
1109 }
1110 return true;
1111 }
1112 }
1113 return false;
1114 }
1115
1116 // Returns true if the AliasType refers to the value field of an
1117 // autobox object. Currently only handles Integer.
1118 static bool is_autobox_object(Compile::AliasType* atp) {
1119 if (atp != NULL && atp->field() != NULL) {
1120 ciField* field = atp->field();
1121 ciSymbol* klass = field->holder()->name();
1122 if (field->name() == ciSymbol::value_name() &&
1123 field->holder()->uses_default_loader() &&
1124 klass == ciSymbol::java_lang_Integer()) {
1125 return true;
1126 }
1127 }
1128 return false;
1129 }
1130
1131
1132 // We're loading from an object which has autobox behaviour.
1133 // If this object is result of a valueOf call we'll have a phi
1134 // merging a newly allocated object and a load from the cache.
1135 // We want to replace this load with the original incoming
1136 // argument to the valueOf call.
1137 Node* LoadNode::eliminate_autobox(PhaseGVN* phase) {
1138 Node* base = in(Address)->in(AddPNode::Base);
1139 if (base->is_Phi() && base->req() == 3) {
1140 AllocateNode* allocation = NULL;
1141 int allocation_index = -1;
1142 int load_index = -1;
1143 for (uint i = 1; i < base->req(); i++) {
1144 allocation = AllocateNode::Ideal_allocation(base->in(i), phase);
1145 if (allocation != NULL) {
1146 allocation_index = i;
1147 load_index = 3 - allocation_index;
1148 break;
1149 }
1150 }
1151 bool has_load = ( allocation != NULL &&
1152 (base->in(load_index)->is_Load() ||
1153 base->in(load_index)->is_DecodeN() &&
1154 base->in(load_index)->in(1)->is_Load()) );
1155 if (has_load && in(Memory)->is_Phi() && in(Memory)->in(0) == base->in(0)) {
1156 // Push the loads from the phi that comes from valueOf up
1157 // through it to allow elimination of the loads and the recovery
1158 // of the original value.
1159 Node* mem_phi = in(Memory);
1160 Node* offset = in(Address)->in(AddPNode::Offset);
1161 Node* region = base->in(0);
1162
1163 Node* in1 = clone();
1164 Node* in1_addr = in1->in(Address)->clone();
1165 in1_addr->set_req(AddPNode::Base, base->in(allocation_index));
1166 in1_addr->set_req(AddPNode::Address, base->in(allocation_index));
1167 in1_addr->set_req(AddPNode::Offset, offset);
1168 in1->set_req(0, region->in(allocation_index));
1169 in1->set_req(Address, in1_addr);
1170 in1->set_req(Memory, mem_phi->in(allocation_index));
1171
1172 Node* in2 = clone();
1173 Node* in2_addr = in2->in(Address)->clone();
1174 in2_addr->set_req(AddPNode::Base, base->in(load_index));
1175 in2_addr->set_req(AddPNode::Address, base->in(load_index));
1176 in2_addr->set_req(AddPNode::Offset, offset);
1177 in2->set_req(0, region->in(load_index));
1178 in2->set_req(Address, in2_addr);
1179 in2->set_req(Memory, mem_phi->in(load_index));
1180
1181 in1_addr = phase->transform(in1_addr);
1182 in1 = phase->transform(in1);
1183 in2_addr = phase->transform(in2_addr);
1184 in2 = phase->transform(in2);
1185
1186 PhiNode* result = PhiNode::make_blank(region, this);
1187 result->set_req(allocation_index, in1);
1188 result->set_req(load_index, in2);
1189 return result;
1190 }
1191 } else if (base->is_Load() ||
1192 base->is_DecodeN() && base->in(1)->is_Load()) {
1193 if (base->is_DecodeN()) {
1194 // Get LoadN node which loads cached Integer object
1195 base = base->in(1);
1196 }
1197 // Eliminate the load of Integer.value for integers from the cache
1198 // array by deriving the value from the index into the array.
1199 // Capture the offset of the load and then reverse the computation.
1200 Node* load_base = base->in(Address)->in(AddPNode::Base);
1201 if (load_base->is_DecodeN()) {
1202 // Get LoadN node which loads IntegerCache.cache field
1203 load_base = load_base->in(1);
1204 }
1205 if (load_base != NULL) {
1206 Compile::AliasType* atp = phase->C->alias_type(load_base->adr_type());
1207 intptr_t cache_offset;
1208 int shift = -1;
1209 Node* cache = NULL;
1210 if (is_autobox_cache(atp)) {
1211 shift = exact_log2(type2aelembytes(T_OBJECT));
1212 cache = AddPNode::Ideal_base_and_offset(load_base->in(Address), phase, cache_offset);
1213 }
1214 if (cache != NULL && base->in(Address)->is_AddP()) {
1215 Node* elements[4];
1216 int count = base->in(Address)->as_AddP()->unpack_offsets(elements, ARRAY_SIZE(elements));
1217 int cache_low;
1218 if (count > 0 && fetch_autobox_base(atp, cache_low)) {
1219 int offset = arrayOopDesc::base_offset_in_bytes(memory_type()) - (cache_low << shift);
1220 // Add up all the offsets making of the address of the load
1221 Node* result = elements[0];
1222 for (int i = 1; i < count; i++) {
1223 result = phase->transform(new (phase->C, 3) AddXNode(result, elements[i]));
1224 }
1225 // Remove the constant offset from the address and then
1226 // remove the scaling of the offset to recover the original index.
1227 result = phase->transform(new (phase->C, 3) AddXNode(result, phase->MakeConX(-offset)));
1228 if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) {
1229 // Peel the shift off directly but wrap it in a dummy node
1230 // since Ideal can't return existing nodes
1231 result = new (phase->C, 3) RShiftXNode(result->in(1), phase->intcon(0));
1232 } else {
1233 result = new (phase->C, 3) RShiftXNode(result, phase->intcon(shift));
1234 }
1235 #ifdef _LP64
1236 result = new (phase->C, 2) ConvL2INode(phase->transform(result));
1237 #endif
1238 return result;
1239 }
1240 }
1241 }
1242 }
1243 return NULL;
1244 }
1245
1246 //------------------------------split_through_phi------------------------------
1247 // Split instance field load through Phi.
1248 Node *LoadNode::split_through_phi(PhaseGVN *phase) {
1249 Node* mem = in(MemNode::Memory);
1250 Node* address = in(MemNode::Address);
1251 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1252 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1253
1254 assert(mem->is_Phi() && (t_oop != NULL) &&
1255 t_oop->is_known_instance_field(), "invalide conditions");
1256
1257 Node *region = mem->in(0);
1258 if (region == NULL) {
1259 return NULL; // Wait stable graph
1260 }
1261 uint cnt = mem->req();
1262 for( uint i = 1; i < cnt; i++ ) {
1263 Node *in = mem->in(i);
1264 if( in == NULL ) {
1265 return NULL; // Wait stable graph
1266 }
1267 }
1268 // Check for loop invariant.
1269 if (cnt == 3) {
1270 for( uint i = 1; i < cnt; i++ ) {
1271 Node *in = mem->in(i);
1272 Node* m = MemNode::optimize_memory_chain(in, addr_t, phase);
1273 if (m == mem) {
1274 set_req(MemNode::Memory, mem->in(cnt - i)); // Skip this phi.
1275 return this;
1276 }
1277 }
1278 }
1279 // Split through Phi (see original code in loopopts.cpp).
1280 assert(phase->C->have_alias_type(addr_t), "instance should have alias type");
1281
1282 // Do nothing here if Identity will find a value
1283 // (to avoid infinite chain of value phis generation).
1284 if ( !phase->eqv(this, this->Identity(phase)) )
1285 return NULL;
1286
1287 // Skip the split if the region dominates some control edge of the address.
1288 if (cnt == 3 && !MemNode::all_controls_dominate(address, region))
1289 return NULL;
1290
1291 const Type* this_type = this->bottom_type();
1292 int this_index = phase->C->get_alias_index(addr_t);
1293 int this_offset = addr_t->offset();
1294 int this_iid = addr_t->is_oopptr()->instance_id();
1295 int wins = 0;
1296 PhaseIterGVN *igvn = phase->is_IterGVN();
1297 Node *phi = new (igvn->C, region->req()) PhiNode(region, this_type, NULL, this_iid, this_index, this_offset);
1298 for( uint i = 1; i < region->req(); i++ ) {
1299 Node *x;
1300 Node* the_clone = NULL;
1301 if( region->in(i) == phase->C->top() ) {
1302 x = phase->C->top(); // Dead path? Use a dead data op
1303 } else {
1304 x = this->clone(); // Else clone up the data op
1305 the_clone = x; // Remember for possible deletion.
1306 // Alter data node to use pre-phi inputs
1307 if( this->in(0) == region ) {
1308 x->set_req( 0, region->in(i) );
1309 } else {
1310 x->set_req( 0, NULL );
1311 }
1312 for( uint j = 1; j < this->req(); j++ ) {
1313 Node *in = this->in(j);
1314 if( in->is_Phi() && in->in(0) == region )
1315 x->set_req( j, in->in(i) ); // Use pre-Phi input for the clone
1316 }
1317 }
1318 // Check for a 'win' on some paths
1319 const Type *t = x->Value(igvn);
1320
1321 bool singleton = t->singleton();
1322
1323 // See comments in PhaseIdealLoop::split_thru_phi().
1324 if( singleton && t == Type::TOP ) {
1325 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1326 }
1327
1328 if( singleton ) {
1329 wins++;
1330 x = igvn->makecon(t);
1331 } else {
1332 // We now call Identity to try to simplify the cloned node.
1333 // Note that some Identity methods call phase->type(this).
1334 // Make sure that the type array is big enough for
1335 // our new node, even though we may throw the node away.
1336 // (This tweaking with igvn only works because x is a new node.)
1337 igvn->set_type(x, t);
1338 // If x is a TypeNode, capture any more-precise type permanently into Node
1339 // otherwise it will be not updated during igvn->transform since
1340 // igvn->type(x) is set to x->Value() already.
1341 x->raise_bottom_type(t);
1342 Node *y = x->Identity(igvn);
1343 if( y != x ) {
1344 wins++;
1345 x = y;
1346 } else {
1347 y = igvn->hash_find(x);
1348 if( y ) {
1349 wins++;
1350 x = y;
1351 } else {
1352 // Else x is a new node we are keeping
1353 // We do not need register_new_node_with_optimizer
1354 // because set_type has already been called.
1355 igvn->_worklist.push(x);
1356 }
1357 }
1358 }
1359 if (x != the_clone && the_clone != NULL)
1360 igvn->remove_dead_node(the_clone);
1361 phi->set_req(i, x);
1362 }
1363 if( wins > 0 ) {
1364 // Record Phi
1365 igvn->register_new_node_with_optimizer(phi);
1366 return phi;
1367 }
1368 igvn->remove_dead_node(phi);
1369 return NULL;
1370 }
1371
1372 //------------------------------Ideal------------------------------------------
1373 // If the load is from Field memory and the pointer is non-null, we can
1374 // zero out the control input.
1375 // If the offset is constant and the base is an object allocation,
1376 // try to hook me up to the exact initializing store.
1377 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1378 Node* p = MemNode::Ideal_common(phase, can_reshape);
1379 if (p) return (p == NodeSentinel) ? NULL : p;
1380
1381 Node* ctrl = in(MemNode::Control);
1382 Node* address = in(MemNode::Address);
1383
1384 // Skip up past a SafePoint control. Cannot do this for Stores because
1385 // pointer stores & cardmarks must stay on the same side of a SafePoint.
1386 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint &&
1387 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw ) {
1388 ctrl = ctrl->in(0);
1389 set_req(MemNode::Control,ctrl);
1390 }
1391
1392 intptr_t ignore = 0;
1393 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1394 if (base != NULL
1395 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
1396 // Check for useless control edge in some common special cases
1397 if (in(MemNode::Control) != NULL
1398 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1399 && all_controls_dominate(base, phase->C->start())) {
1400 // A method-invariant, non-null address (constant or 'this' argument).
1401 set_req(MemNode::Control, NULL);
1402 }
1403
1404 if (EliminateAutoBox && can_reshape) {
1405 assert(!phase->type(base)->higher_equal(TypePtr::NULL_PTR), "the autobox pointer should be non-null");
1406 Compile::AliasType* atp = phase->C->alias_type(adr_type());
1407 if (is_autobox_object(atp)) {
1408 Node* result = eliminate_autobox(phase);
1409 if (result != NULL) return result;
1410 }
1411 }
1412 }
1413
1414 Node* mem = in(MemNode::Memory);
1415 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1416
1417 if (addr_t != NULL) {
1418 // try to optimize our memory input
1419 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, phase);
1420 if (opt_mem != mem) {
1421 set_req(MemNode::Memory, opt_mem);
1422 if (phase->type( opt_mem ) == Type::TOP) return NULL;
1423 return this;
1424 }
1425 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1426 if (can_reshape && opt_mem->is_Phi() &&
1427 (t_oop != NULL) && t_oop->is_known_instance_field()) {
1428 // Split instance field load through Phi.
1429 Node* result = split_through_phi(phase);
1430 if (result != NULL) return result;
1431 }
1432 }
1433
1434 // Check for prior store with a different base or offset; make Load
1435 // independent. Skip through any number of them. Bail out if the stores
1436 // are in an endless dead cycle and report no progress. This is a key
1437 // transform for Reflection. However, if after skipping through the Stores
1438 // we can't then fold up against a prior store do NOT do the transform as
1439 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
1440 // array memory alive twice: once for the hoisted Load and again after the
1441 // bypassed Store. This situation only works if EVERYBODY who does
1442 // anti-dependence work knows how to bypass. I.e. we need all
1443 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
1444 // the alias index stuff. So instead, peek through Stores and IFF we can
1445 // fold up, do so.
1446 Node* prev_mem = find_previous_store(phase);
1447 // Steps (a), (b): Walk past independent stores to find an exact match.
1448 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) {
1449 // (c) See if we can fold up on the spot, but don't fold up here.
1450 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
1451 // just return a prior value, which is done by Identity calls.
1452 if (can_see_stored_value(prev_mem, phase)) {
1453 // Make ready for step (d):
1454 set_req(MemNode::Memory, prev_mem);
1455 return this;
1456 }
1457 }
1458
1459 return NULL; // No further progress
1460 }
1461
1462 // Helper to recognize certain Klass fields which are invariant across
1463 // some group of array types (e.g., int[] or all T[] where T < Object).
1464 const Type*
1465 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1466 ciKlass* klass) const {
1467 if (tkls->offset() == Klass::modifier_flags_offset_in_bytes() + (int)sizeof(oopDesc)) {
1468 // The field is Klass::_modifier_flags. Return its (constant) value.
1469 // (Folds up the 2nd indirection in aClassConstant.getModifiers().)
1470 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags");
1471 return TypeInt::make(klass->modifier_flags());
1472 }
1473 if (tkls->offset() == Klass::access_flags_offset_in_bytes() + (int)sizeof(oopDesc)) {
1474 // The field is Klass::_access_flags. Return its (constant) value.
1475 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1476 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags");
1477 return TypeInt::make(klass->access_flags());
1478 }
1479 if (tkls->offset() == Klass::layout_helper_offset_in_bytes() + (int)sizeof(oopDesc)) {
1480 // The field is Klass::_layout_helper. Return its constant value if known.
1481 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper");
1482 return TypeInt::make(klass->layout_helper());
1483 }
1484
1485 // No match.
1486 return NULL;
1487 }
1488
1489 //------------------------------Value-----------------------------------------
1490 const Type *LoadNode::Value( PhaseTransform *phase ) const {
1491 // Either input is TOP ==> the result is TOP
1492 Node* mem = in(MemNode::Memory);
1493 const Type *t1 = phase->type(mem);
1494 if (t1 == Type::TOP) return Type::TOP;
1495 Node* adr = in(MemNode::Address);
1496 const TypePtr* tp = phase->type(adr)->isa_ptr();
1497 if (tp == NULL || tp->empty()) return Type::TOP;
1498 int off = tp->offset();
1499 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
1500
1501 // Try to guess loaded type from pointer type
1502 if (tp->base() == Type::AryPtr) {
1503 const Type *t = tp->is_aryptr()->elem();
1504 // Don't do this for integer types. There is only potential profit if
1505 // the element type t is lower than _type; that is, for int types, if _type is
1506 // more restrictive than t. This only happens here if one is short and the other
1507 // char (both 16 bits), and in those cases we've made an intentional decision
1508 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
1509 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
1510 //
1511 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
1512 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
1513 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
1514 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
1515 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
1516 // In fact, that could have been the original type of p1, and p1 could have
1517 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
1518 // expression (LShiftL quux 3) independently optimized to the constant 8.
1519 if ((t->isa_int() == NULL) && (t->isa_long() == NULL)
1520 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
1521 // t might actually be lower than _type, if _type is a unique
1522 // concrete subclass of abstract class t.
1523 // Make sure the reference is not into the header, by comparing
1524 // the offset against the offset of the start of the array's data.
1525 // Different array types begin at slightly different offsets (12 vs. 16).
1526 // We choose T_BYTE as an example base type that is least restrictive
1527 // as to alignment, which will therefore produce the smallest
1528 // possible base offset.
1529 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
1530 if ((uint)off >= (uint)min_base_off) { // is the offset beyond the header?
1531 const Type* jt = t->join(_type);
1532 // In any case, do not allow the join, per se, to empty out the type.
1533 if (jt->empty() && !t->empty()) {
1534 // This can happen if a interface-typed array narrows to a class type.
1535 jt = _type;
1536 }
1537
1538 if (EliminateAutoBox && adr->is_AddP()) {
1539 // The pointers in the autobox arrays are always non-null
1540 Node* base = adr->in(AddPNode::Base);
1541 if (base != NULL &&
1542 !phase->type(base)->higher_equal(TypePtr::NULL_PTR)) {
1543 Compile::AliasType* atp = phase->C->alias_type(base->adr_type());
1544 if (is_autobox_cache(atp)) {
1545 return jt->join(TypePtr::NOTNULL)->is_ptr();
1546 }
1547 }
1548 }
1549 return jt;
1550 }
1551 }
1552 } else if (tp->base() == Type::InstPtr) {
1553 const TypeInstPtr* tinst = tp->is_instptr();
1554 ciKlass* klass = tinst->klass();
1555 assert( off != Type::OffsetBot ||
1556 // arrays can be cast to Objects
1557 tp->is_oopptr()->klass()->is_java_lang_Object() ||
1558 // unsafe field access may not have a constant offset
1559 phase->C->has_unsafe_access(),
1560 "Field accesses must be precise" );
1561 // For oop loads, we expect the _type to be precise
1562 if (OptimizeStringConcat && klass == phase->C->env()->String_klass() &&
1563 adr->is_AddP() && off != Type::OffsetBot) {
1564 // For constant Strings treat the fields as compile time constants.
1565 Node* base = adr->in(AddPNode::Base);
1566 const TypeOopPtr* t = phase->type(base)->isa_oopptr();
1567 if (t != NULL && t->singleton()) {
1568 ciObject* string = t->const_oop();
1569 ciConstant constant = string->as_instance()->field_value_by_offset(off);
1570 if (constant.basic_type() == T_INT) {
1571 return TypeInt::make(constant.as_int());
1572 } else if (constant.basic_type() == T_ARRAY) {
1573 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
1574 return TypeNarrowOop::make_from_constant(constant.as_object());
1575 } else {
1576 return TypeOopPtr::make_from_constant(constant.as_object());
1577 }
1578 }
1579 }
1580 }
1581 } else if (tp->base() == Type::KlassPtr) {
1582 assert( off != Type::OffsetBot ||
1583 // arrays can be cast to Objects
1584 tp->is_klassptr()->klass()->is_java_lang_Object() ||
1585 // also allow array-loading from the primary supertype
1586 // array during subtype checks
1587 Opcode() == Op_LoadKlass,
1588 "Field accesses must be precise" );
1589 // For klass/static loads, we expect the _type to be precise
1590 }
1591
1592 const TypeKlassPtr *tkls = tp->isa_klassptr();
1593 if (tkls != NULL && !StressReflectiveCode) {
1594 ciKlass* klass = tkls->klass();
1595 if (klass->is_loaded() && tkls->klass_is_exact()) {
1596 // We are loading a field from a Klass metaobject whose identity
1597 // is known at compile time (the type is "exact" or "precise").
1598 // Check for fields we know are maintained as constants by the VM.
1599 if (tkls->offset() == Klass::super_check_offset_offset_in_bytes() + (int)sizeof(oopDesc)) {
1600 // The field is Klass::_super_check_offset. Return its (constant) value.
1601 // (Folds up type checking code.)
1602 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
1603 return TypeInt::make(klass->super_check_offset());
1604 }
1605 // Compute index into primary_supers array
1606 juint depth = (tkls->offset() - (Klass::primary_supers_offset_in_bytes() + (int)sizeof(oopDesc))) / sizeof(klassOop);
1607 // Check for overflowing; use unsigned compare to handle the negative case.
1608 if( depth < ciKlass::primary_super_limit() ) {
1609 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1610 // (Folds up type checking code.)
1611 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1612 ciKlass *ss = klass->super_of_depth(depth);
1613 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1614 }
1615 const Type* aift = load_array_final_field(tkls, klass);
1616 if (aift != NULL) return aift;
1617 if (tkls->offset() == in_bytes(arrayKlass::component_mirror_offset()) + (int)sizeof(oopDesc)
1618 && klass->is_array_klass()) {
1619 // The field is arrayKlass::_component_mirror. Return its (constant) value.
1620 // (Folds up aClassConstant.getComponentType, common in Arrays.copyOf.)
1621 assert(Opcode() == Op_LoadP, "must load an oop from _component_mirror");
1622 return TypeInstPtr::make(klass->as_array_klass()->component_mirror());
1623 }
1624 if (tkls->offset() == Klass::java_mirror_offset_in_bytes() + (int)sizeof(oopDesc)) {
1625 // The field is Klass::_java_mirror. Return its (constant) value.
1626 // (Folds up the 2nd indirection in anObjConstant.getClass().)
1627 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
1628 return TypeInstPtr::make(klass->java_mirror());
1629 }
1630 }
1631
1632 // We can still check if we are loading from the primary_supers array at a
1633 // shallow enough depth. Even though the klass is not exact, entries less
1634 // than or equal to its super depth are correct.
1635 if (klass->is_loaded() ) {
1636 ciType *inner = klass->klass();
1637 while( inner->is_obj_array_klass() )
1638 inner = inner->as_obj_array_klass()->base_element_type();
1639 if( inner->is_instance_klass() &&
1640 !inner->as_instance_klass()->flags().is_interface() ) {
1641 // Compute index into primary_supers array
1642 juint depth = (tkls->offset() - (Klass::primary_supers_offset_in_bytes() + (int)sizeof(oopDesc))) / sizeof(klassOop);
1643 // Check for overflowing; use unsigned compare to handle the negative case.
1644 if( depth < ciKlass::primary_super_limit() &&
1645 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case
1646 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1647 // (Folds up type checking code.)
1648 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1649 ciKlass *ss = klass->super_of_depth(depth);
1650 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1651 }
1652 }
1653 }
1654
1655 // If the type is enough to determine that the thing is not an array,
1656 // we can give the layout_helper a positive interval type.
1657 // This will help short-circuit some reflective code.
1658 if (tkls->offset() == Klass::layout_helper_offset_in_bytes() + (int)sizeof(oopDesc)
1659 && !klass->is_array_klass() // not directly typed as an array
1660 && !klass->is_interface() // specifically not Serializable & Cloneable
1661 && !klass->is_java_lang_Object() // not the supertype of all T[]
1662 ) {
1663 // Note: When interfaces are reliable, we can narrow the interface
1664 // test to (klass != Serializable && klass != Cloneable).
1665 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
1666 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
1667 // The key property of this type is that it folds up tests
1668 // for array-ness, since it proves that the layout_helper is positive.
1669 // Thus, a generic value like the basic object layout helper works fine.
1670 return TypeInt::make(min_size, max_jint, Type::WidenMin);
1671 }
1672 }
1673
1674 // If we are loading from a freshly-allocated object, produce a zero,
1675 // if the load is provably beyond the header of the object.
1676 // (Also allow a variable load from a fresh array to produce zero.)
1677 if (ReduceFieldZeroing) {
1678 Node* value = can_see_stored_value(mem,phase);
1679 if (value != NULL && value->is_Con())
1680 return value->bottom_type();
1681 }
1682
1683 const TypeOopPtr *tinst = tp->isa_oopptr();
1684 if (tinst != NULL && tinst->is_known_instance_field()) {
1685 // If we have an instance type and our memory input is the
1686 // programs's initial memory state, there is no matching store,
1687 // so just return a zero of the appropriate type
1688 Node *mem = in(MemNode::Memory);
1689 if (mem->is_Parm() && mem->in(0)->is_Start()) {
1690 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
1691 return Type::get_zero_type(_type->basic_type());
1692 }
1693 }
1694 return _type;
1695 }
1696
1697 //------------------------------match_edge-------------------------------------
1698 // Do we Match on this edge index or not? Match only the address.
1699 uint LoadNode::match_edge(uint idx) const {
1700 return idx == MemNode::Address;
1701 }
1702
1703 //--------------------------LoadBNode::Ideal--------------------------------------
1704 //
1705 // If the previous store is to the same address as this load,
1706 // and the value stored was larger than a byte, replace this load
1707 // with the value stored truncated to a byte. If no truncation is
1708 // needed, the replacement is done in LoadNode::Identity().
1709 //
1710 Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1711 Node* mem = in(MemNode::Memory);
1712 Node* value = can_see_stored_value(mem,phase);
1713 if( value && !phase->type(value)->higher_equal( _type ) ) {
1714 Node *result = phase->transform( new (phase->C, 3) LShiftINode(value, phase->intcon(24)) );
1715 return new (phase->C, 3) RShiftINode(result, phase->intcon(24));
1716 }
1717 // Identity call will handle the case where truncation is not needed.
1718 return LoadNode::Ideal(phase, can_reshape);
1719 }
1720
1721 //--------------------------LoadUBNode::Ideal-------------------------------------
1722 //
1723 // If the previous store is to the same address as this load,
1724 // and the value stored was larger than a byte, replace this load
1725 // with the value stored truncated to a byte. If no truncation is
1726 // needed, the replacement is done in LoadNode::Identity().
1727 //
1728 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
1729 Node* mem = in(MemNode::Memory);
1730 Node* value = can_see_stored_value(mem, phase);
1731 if (value && !phase->type(value)->higher_equal(_type))
1732 return new (phase->C, 3) AndINode(value, phase->intcon(0xFF));
1733 // Identity call will handle the case where truncation is not needed.
1734 return LoadNode::Ideal(phase, can_reshape);
1735 }
1736
1737 //--------------------------LoadUSNode::Ideal-------------------------------------
1738 //
1739 // If the previous store is to the same address as this load,
1740 // and the value stored was larger than a char, replace this load
1741 // with the value stored truncated to a char. If no truncation is
1742 // needed, the replacement is done in LoadNode::Identity().
1743 //
1744 Node *LoadUSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1745 Node* mem = in(MemNode::Memory);
1746 Node* value = can_see_stored_value(mem,phase);
1747 if( value && !phase->type(value)->higher_equal( _type ) )
1748 return new (phase->C, 3) AndINode(value,phase->intcon(0xFFFF));
1749 // Identity call will handle the case where truncation is not needed.
1750 return LoadNode::Ideal(phase, can_reshape);
1751 }
1752
1753 //--------------------------LoadSNode::Ideal--------------------------------------
1754 //
1755 // If the previous store is to the same address as this load,
1756 // and the value stored was larger than a short, replace this load
1757 // with the value stored truncated to a short. If no truncation is
1758 // needed, the replacement is done in LoadNode::Identity().
1759 //
1760 Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1761 Node* mem = in(MemNode::Memory);
1762 Node* value = can_see_stored_value(mem,phase);
1763 if( value && !phase->type(value)->higher_equal( _type ) ) {
1764 Node *result = phase->transform( new (phase->C, 3) LShiftINode(value, phase->intcon(16)) );
1765 return new (phase->C, 3) RShiftINode(result, phase->intcon(16));
1766 }
1767 // Identity call will handle the case where truncation is not needed.
1768 return LoadNode::Ideal(phase, can_reshape);
1769 }
1770
1771 //=============================================================================
1772 //----------------------------LoadKlassNode::make------------------------------
1773 // Polymorphic factory method:
1774 Node *LoadKlassNode::make( PhaseGVN& gvn, Node *mem, Node *adr, const TypePtr* at, const TypeKlassPtr *tk ) {
1775 Compile* C = gvn.C;
1776 Node *ctl = NULL;
1777 // sanity check the alias category against the created node type
1778 const TypeOopPtr *adr_type = adr->bottom_type()->isa_oopptr();
1779 assert(adr_type != NULL, "expecting TypeOopPtr");
1780 #ifdef _LP64
1781 if (adr_type->is_ptr_to_narrowoop()) {
1782 Node* load_klass = gvn.transform(new (C, 3) LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowoop()));
1783 return new (C, 2) DecodeNNode(load_klass, load_klass->bottom_type()->make_ptr());
1784 }
1785 #endif
1786 assert(!adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
1787 return new (C, 3) LoadKlassNode(ctl, mem, adr, at, tk);
1788 }
1789
1790 //------------------------------Value------------------------------------------
1791 const Type *LoadKlassNode::Value( PhaseTransform *phase ) const {
1792 return klass_value_common(phase);
1793 }
1794
1795 const Type *LoadNode::klass_value_common( PhaseTransform *phase ) const {
1796 // Either input is TOP ==> the result is TOP
1797 const Type *t1 = phase->type( in(MemNode::Memory) );
1798 if (t1 == Type::TOP) return Type::TOP;
1799 Node *adr = in(MemNode::Address);
1800 const Type *t2 = phase->type( adr );
1801 if (t2 == Type::TOP) return Type::TOP;
1802 const TypePtr *tp = t2->is_ptr();
1803 if (TypePtr::above_centerline(tp->ptr()) ||
1804 tp->ptr() == TypePtr::Null) return Type::TOP;
1805
1806 // Return a more precise klass, if possible
1807 const TypeInstPtr *tinst = tp->isa_instptr();
1808 if (tinst != NULL) {
1809 ciInstanceKlass* ik = tinst->klass()->as_instance_klass();
1810 int offset = tinst->offset();
1811 if (ik == phase->C->env()->Class_klass()
1812 && (offset == java_lang_Class::klass_offset_in_bytes() ||
1813 offset == java_lang_Class::array_klass_offset_in_bytes())) {
1814 // We are loading a special hidden field from a Class mirror object,
1815 // the field which points to the VM's Klass metaobject.
1816 ciType* t = tinst->java_mirror_type();
1817 // java_mirror_type returns non-null for compile-time Class constants.
1818 if (t != NULL) {
1819 // constant oop => constant klass
1820 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
1821 return TypeKlassPtr::make(ciArrayKlass::make(t));
1822 }
1823 if (!t->is_klass()) {
1824 // a primitive Class (e.g., int.class) has NULL for a klass field
1825 return TypePtr::NULL_PTR;
1826 }
1827 // (Folds up the 1st indirection in aClassConstant.getModifiers().)
1828 return TypeKlassPtr::make(t->as_klass());
1829 }
1830 // non-constant mirror, so we can't tell what's going on
1831 }
1832 if( !ik->is_loaded() )
1833 return _type; // Bail out if not loaded
1834 if (offset == oopDesc::klass_offset_in_bytes()) {
1835 if (tinst->klass_is_exact()) {
1836 return TypeKlassPtr::make(ik);
1837 }
1838 // See if we can become precise: no subklasses and no interface
1839 // (Note: We need to support verified interfaces.)
1840 if (!ik->is_interface() && !ik->has_subklass()) {
1841 //assert(!UseExactTypes, "this code should be useless with exact types");
1842 // Add a dependence; if any subclass added we need to recompile
1843 if (!ik->is_final()) {
1844 // %%% should use stronger assert_unique_concrete_subtype instead
1845 phase->C->dependencies()->assert_leaf_type(ik);
1846 }
1847 // Return precise klass
1848 return TypeKlassPtr::make(ik);
1849 }
1850
1851 // Return root of possible klass
1852 return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/);
1853 }
1854 }
1855
1856 // Check for loading klass from an array
1857 const TypeAryPtr *tary = tp->isa_aryptr();
1858 if( tary != NULL ) {
1859 ciKlass *tary_klass = tary->klass();
1860 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP
1861 && tary->offset() == oopDesc::klass_offset_in_bytes()) {
1862 if (tary->klass_is_exact()) {
1863 return TypeKlassPtr::make(tary_klass);
1864 }
1865 ciArrayKlass *ak = tary->klass()->as_array_klass();
1866 // If the klass is an object array, we defer the question to the
1867 // array component klass.
1868 if( ak->is_obj_array_klass() ) {
1869 assert( ak->is_loaded(), "" );
1870 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass();
1871 if( base_k->is_loaded() && base_k->is_instance_klass() ) {
1872 ciInstanceKlass* ik = base_k->as_instance_klass();
1873 // See if we can become precise: no subklasses and no interface
1874 if (!ik->is_interface() && !ik->has_subklass()) {
1875 //assert(!UseExactTypes, "this code should be useless with exact types");
1876 // Add a dependence; if any subclass added we need to recompile
1877 if (!ik->is_final()) {
1878 phase->C->dependencies()->assert_leaf_type(ik);
1879 }
1880 // Return precise array klass
1881 return TypeKlassPtr::make(ak);
1882 }
1883 }
1884 return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/);
1885 } else { // Found a type-array?
1886 //assert(!UseExactTypes, "this code should be useless with exact types");
1887 assert( ak->is_type_array_klass(), "" );
1888 return TypeKlassPtr::make(ak); // These are always precise
1889 }
1890 }
1891 }
1892
1893 // Check for loading klass from an array klass
1894 const TypeKlassPtr *tkls = tp->isa_klassptr();
1895 if (tkls != NULL && !StressReflectiveCode) {
1896 ciKlass* klass = tkls->klass();
1897 if( !klass->is_loaded() )
1898 return _type; // Bail out if not loaded
1899 if( klass->is_obj_array_klass() &&
1900 (uint)tkls->offset() == objArrayKlass::element_klass_offset_in_bytes() + sizeof(oopDesc)) {
1901 ciKlass* elem = klass->as_obj_array_klass()->element_klass();
1902 // // Always returning precise element type is incorrect,
1903 // // e.g., element type could be object and array may contain strings
1904 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
1905
1906 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
1907 // according to the element type's subclassing.
1908 return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/);
1909 }
1910 if( klass->is_instance_klass() && tkls->klass_is_exact() &&
1911 (uint)tkls->offset() == Klass::super_offset_in_bytes() + sizeof(oopDesc)) {
1912 ciKlass* sup = klass->as_instance_klass()->super();
1913 // The field is Klass::_super. Return its (constant) value.
1914 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
1915 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR;
1916 }
1917 }
1918
1919 // Bailout case
1920 return LoadNode::Value(phase);
1921 }
1922
1923 //------------------------------Identity---------------------------------------
1924 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
1925 // Also feed through the klass in Allocate(...klass...)._klass.
1926 Node* LoadKlassNode::Identity( PhaseTransform *phase ) {
1927 return klass_identity_common(phase);
1928 }
1929
1930 Node* LoadNode::klass_identity_common(PhaseTransform *phase ) {
1931 Node* x = LoadNode::Identity(phase);
1932 if (x != this) return x;
1933
1934 // Take apart the address into an oop and and offset.
1935 // Return 'this' if we cannot.
1936 Node* adr = in(MemNode::Address);
1937 intptr_t offset = 0;
1938 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
1939 if (base == NULL) return this;
1940 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
1941 if (toop == NULL) return this;
1942
1943 // We can fetch the klass directly through an AllocateNode.
1944 // This works even if the klass is not constant (clone or newArray).
1945 if (offset == oopDesc::klass_offset_in_bytes()) {
1946 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
1947 if (allocated_klass != NULL) {
1948 return allocated_klass;
1949 }
1950 }
1951
1952 // Simplify k.java_mirror.as_klass to plain k, where k is a klassOop.
1953 // Simplify ak.component_mirror.array_klass to plain ak, ak an arrayKlass.
1954 // See inline_native_Class_query for occurrences of these patterns.
1955 // Java Example: x.getClass().isAssignableFrom(y)
1956 // Java Example: Array.newInstance(x.getClass().getComponentType(), n)
1957 //
1958 // This improves reflective code, often making the Class
1959 // mirror go completely dead. (Current exception: Class
1960 // mirrors may appear in debug info, but we could clean them out by
1961 // introducing a new debug info operator for klassOop.java_mirror).
1962 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass()
1963 && (offset == java_lang_Class::klass_offset_in_bytes() ||
1964 offset == java_lang_Class::array_klass_offset_in_bytes())) {
1965 // We are loading a special hidden field from a Class mirror,
1966 // the field which points to its Klass or arrayKlass metaobject.
1967 if (base->is_Load()) {
1968 Node* adr2 = base->in(MemNode::Address);
1969 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
1970 if (tkls != NULL && !tkls->empty()
1971 && (tkls->klass()->is_instance_klass() ||
1972 tkls->klass()->is_array_klass())
1973 && adr2->is_AddP()
1974 ) {
1975 int mirror_field = Klass::java_mirror_offset_in_bytes();
1976 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
1977 mirror_field = in_bytes(arrayKlass::component_mirror_offset());
1978 }
1979 if (tkls->offset() == mirror_field + (int)sizeof(oopDesc)) {
1980 return adr2->in(AddPNode::Base);
1981 }
1982 }
1983 }
1984 }
1985
1986 return this;
1987 }
1988
1989
1990 //------------------------------Value------------------------------------------
1991 const Type *LoadNKlassNode::Value( PhaseTransform *phase ) const {
1992 const Type *t = klass_value_common(phase);
1993 if (t == Type::TOP)
1994 return t;
1995
1996 return t->make_narrowoop();
1997 }
1998
1999 //------------------------------Identity---------------------------------------
2000 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
2001 // Also feed through the klass in Allocate(...klass...)._klass.
2002 Node* LoadNKlassNode::Identity( PhaseTransform *phase ) {
2003 Node *x = klass_identity_common(phase);
2004
2005 const Type *t = phase->type( x );
2006 if( t == Type::TOP ) return x;
2007 if( t->isa_narrowoop()) return x;
2008
2009 return phase->transform(new (phase->C, 2) EncodePNode(x, t->make_narrowoop()));
2010 }
2011
2012 //------------------------------Value-----------------------------------------
2013 const Type *LoadRangeNode::Value( PhaseTransform *phase ) const {
2014 // Either input is TOP ==> the result is TOP
2015 const Type *t1 = phase->type( in(MemNode::Memory) );
2016 if( t1 == Type::TOP ) return Type::TOP;
2017 Node *adr = in(MemNode::Address);
2018 const Type *t2 = phase->type( adr );
2019 if( t2 == Type::TOP ) return Type::TOP;
2020 const TypePtr *tp = t2->is_ptr();
2021 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
2022 const TypeAryPtr *tap = tp->isa_aryptr();
2023 if( !tap ) return _type;
2024 return tap->size();
2025 }
2026
2027 //-------------------------------Ideal---------------------------------------
2028 // Feed through the length in AllocateArray(...length...)._length.
2029 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2030 Node* p = MemNode::Ideal_common(phase, can_reshape);
2031 if (p) return (p == NodeSentinel) ? NULL : p;
2032
2033 // Take apart the address into an oop and and offset.
2034 // Return 'this' if we cannot.
2035 Node* adr = in(MemNode::Address);
2036 intptr_t offset = 0;
2037 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2038 if (base == NULL) return NULL;
2039 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2040 if (tary == NULL) return NULL;
2041
2042 // We can fetch the length directly through an AllocateArrayNode.
2043 // This works even if the length is not constant (clone or newArray).
2044 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2045 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2046 if (alloc != NULL) {
2047 Node* allocated_length = alloc->Ideal_length();
2048 Node* len = alloc->make_ideal_length(tary, phase);
2049 if (allocated_length != len) {
2050 // New CastII improves on this.
2051 return len;
2052 }
2053 }
2054 }
2055
2056 return NULL;
2057 }
2058
2059 //------------------------------Identity---------------------------------------
2060 // Feed through the length in AllocateArray(...length...)._length.
2061 Node* LoadRangeNode::Identity( PhaseTransform *phase ) {
2062 Node* x = LoadINode::Identity(phase);
2063 if (x != this) return x;
2064
2065 // Take apart the address into an oop and and offset.
2066 // Return 'this' if we cannot.
2067 Node* adr = in(MemNode::Address);
2068 intptr_t offset = 0;
2069 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2070 if (base == NULL) return this;
2071 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2072 if (tary == NULL) return this;
2073
2074 // We can fetch the length directly through an AllocateArrayNode.
2075 // This works even if the length is not constant (clone or newArray).
2076 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2077 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2078 if (alloc != NULL) {
2079 Node* allocated_length = alloc->Ideal_length();
2080 // Do not allow make_ideal_length to allocate a CastII node.
2081 Node* len = alloc->make_ideal_length(tary, phase, false);
2082 if (allocated_length == len) {
2083 // Return allocated_length only if it would not be improved by a CastII.
2084 return allocated_length;
2085 }
2086 }
2087 }
2088
2089 return this;
2090
2091 }
2092
2093 //=============================================================================
2094 //---------------------------StoreNode::make-----------------------------------
2095 // Polymorphic factory method:
2096 StoreNode* StoreNode::make( PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt ) {
2097 Compile* C = gvn.C;
2098 assert( C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2099 ctl != NULL, "raw memory operations should have control edge");
2100
2101 switch (bt) {
2102 case T_BOOLEAN:
2103 case T_BYTE: return new (C, 4) StoreBNode(ctl, mem, adr, adr_type, val);
2104 case T_INT: return new (C, 4) StoreINode(ctl, mem, adr, adr_type, val);
2105 case T_CHAR:
2106 case T_SHORT: return new (C, 4) StoreCNode(ctl, mem, adr, adr_type, val);
2107 case T_LONG: return new (C, 4) StoreLNode(ctl, mem, adr, adr_type, val);
2108 case T_FLOAT: return new (C, 4) StoreFNode(ctl, mem, adr, adr_type, val);
2109 case T_DOUBLE: return new (C, 4) StoreDNode(ctl, mem, adr, adr_type, val);
2110 case T_ADDRESS:
2111 case T_OBJECT:
2112 #ifdef _LP64
2113 if (adr->bottom_type()->is_ptr_to_narrowoop() ||
2114 (UseCompressedOops && val->bottom_type()->isa_klassptr() &&
2115 adr->bottom_type()->isa_rawptr())) {
2116 val = gvn.transform(new (C, 2) EncodePNode(val, val->bottom_type()->make_narrowoop()));
2117 return new (C, 4) StoreNNode(ctl, mem, adr, adr_type, val);
2118 } else
2119 #endif
2120 {
2121 return new (C, 4) StorePNode(ctl, mem, adr, adr_type, val);
2122 }
2123 }
2124 ShouldNotReachHere();
2125 return (StoreNode*)NULL;
2126 }
2127
2128 StoreLNode* StoreLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val) {
2129 bool require_atomic = true;
2130 return new (C, 4) StoreLNode(ctl, mem, adr, adr_type, val, require_atomic);
2131 }
2132
2133
2134 //--------------------------bottom_type----------------------------------------
2135 const Type *StoreNode::bottom_type() const {
2136 return Type::MEMORY;
2137 }
2138
2139 //------------------------------hash-------------------------------------------
2140 uint StoreNode::hash() const {
2141 // unroll addition of interesting fields
2142 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2143
2144 // Since they are not commoned, do not hash them:
2145 return NO_HASH;
2146 }
2147
2148 //------------------------------Ideal------------------------------------------
2149 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
2150 // When a store immediately follows a relevant allocation/initialization,
2151 // try to capture it into the initialization, or hoist it above.
2152 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2153 Node* p = MemNode::Ideal_common(phase, can_reshape);
2154 if (p) return (p == NodeSentinel) ? NULL : p;
2155
2156 Node* mem = in(MemNode::Memory);
2157 Node* address = in(MemNode::Address);
2158
2159 // Back-to-back stores to same address? Fold em up.
2160 // Generally unsafe if I have intervening uses...
2161 if (mem->is_Store() && phase->eqv_uncast(mem->in(MemNode::Address), address)) {
2162 // Looking at a dead closed cycle of memory?
2163 assert(mem != mem->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
2164
2165 assert(Opcode() == mem->Opcode() ||
2166 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw,
2167 "no mismatched stores, except on raw memory");
2168
2169 if (mem->outcnt() == 1 && // check for intervening uses
2170 mem->as_Store()->memory_size() <= this->memory_size()) {
2171 // If anybody other than 'this' uses 'mem', we cannot fold 'mem' away.
2172 // For example, 'mem' might be the final state at a conditional return.
2173 // Or, 'mem' might be used by some node which is live at the same time
2174 // 'this' is live, which might be unschedulable. So, require exactly
2175 // ONE user, the 'this' store, until such time as we clone 'mem' for
2176 // each of 'mem's uses (thus making the exactly-1-user-rule hold true).
2177 if (can_reshape) { // (%%% is this an anachronism?)
2178 set_req_X(MemNode::Memory, mem->in(MemNode::Memory),
2179 phase->is_IterGVN());
2180 } else {
2181 // It's OK to do this in the parser, since DU info is always accurate,
2182 // and the parser always refers to nodes via SafePointNode maps.
2183 set_req(MemNode::Memory, mem->in(MemNode::Memory));
2184 }
2185 return this;
2186 }
2187 }
2188
2189 // Capture an unaliased, unconditional, simple store into an initializer.
2190 // Or, if it is independent of the allocation, hoist it above the allocation.
2191 if (ReduceFieldZeroing && /*can_reshape &&*/
2192 mem->is_Proj() && mem->in(0)->is_Initialize()) {
2193 InitializeNode* init = mem->in(0)->as_Initialize();
2194 intptr_t offset = init->can_capture_store(this, phase);
2195 if (offset > 0) {
2196 Node* moved = init->capture_store(this, offset, phase);
2197 // If the InitializeNode captured me, it made a raw copy of me,
2198 // and I need to disappear.
2199 if (moved != NULL) {
2200 // %%% hack to ensure that Ideal returns a new node:
2201 mem = MergeMemNode::make(phase->C, mem);
2202 return mem; // fold me away
2203 }
2204 }
2205 }
2206
2207 return NULL; // No further progress
2208 }
2209
2210 //------------------------------Value-----------------------------------------
2211 const Type *StoreNode::Value( PhaseTransform *phase ) const {
2212 // Either input is TOP ==> the result is TOP
2213 const Type *t1 = phase->type( in(MemNode::Memory) );
2214 if( t1 == Type::TOP ) return Type::TOP;
2215 const Type *t2 = phase->type( in(MemNode::Address) );
2216 if( t2 == Type::TOP ) return Type::TOP;
2217 const Type *t3 = phase->type( in(MemNode::ValueIn) );
2218 if( t3 == Type::TOP ) return Type::TOP;
2219 return Type::MEMORY;
2220 }
2221
2222 //------------------------------Identity---------------------------------------
2223 // Remove redundant stores:
2224 // Store(m, p, Load(m, p)) changes to m.
2225 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
2226 Node *StoreNode::Identity( PhaseTransform *phase ) {
2227 Node* mem = in(MemNode::Memory);
2228 Node* adr = in(MemNode::Address);
2229 Node* val = in(MemNode::ValueIn);
2230
2231 // Load then Store? Then the Store is useless
2232 if (val->is_Load() &&
2233 phase->eqv_uncast( val->in(MemNode::Address), adr ) &&
2234 phase->eqv_uncast( val->in(MemNode::Memory ), mem ) &&
2235 val->as_Load()->store_Opcode() == Opcode()) {
2236 return mem;
2237 }
2238
2239 // Two stores in a row of the same value?
2240 if (mem->is_Store() &&
2241 phase->eqv_uncast( mem->in(MemNode::Address), adr ) &&
2242 phase->eqv_uncast( mem->in(MemNode::ValueIn), val ) &&
2243 mem->Opcode() == Opcode()) {
2244 return mem;
2245 }
2246
2247 // Store of zero anywhere into a freshly-allocated object?
2248 // Then the store is useless.
2249 // (It must already have been captured by the InitializeNode.)
2250 if (ReduceFieldZeroing && phase->type(val)->is_zero_type()) {
2251 // a newly allocated object is already all-zeroes everywhere
2252 if (mem->is_Proj() && mem->in(0)->is_Allocate()) {
2253 return mem;
2254 }
2255
2256 // the store may also apply to zero-bits in an earlier object
2257 Node* prev_mem = find_previous_store(phase);
2258 // Steps (a), (b): Walk past independent stores to find an exact match.
2259 if (prev_mem != NULL) {
2260 Node* prev_val = can_see_stored_value(prev_mem, phase);
2261 if (prev_val != NULL && phase->eqv(prev_val, val)) {
2262 // prev_val and val might differ by a cast; it would be good
2263 // to keep the more informative of the two.
2264 return mem;
2265 }
2266 }
2267 }
2268
2269 return this;
2270 }
2271
2272 //------------------------------match_edge-------------------------------------
2273 // Do we Match on this edge index or not? Match only memory & value
2274 uint StoreNode::match_edge(uint idx) const {
2275 return idx == MemNode::Address || idx == MemNode::ValueIn;
2276 }
2277
2278 //------------------------------cmp--------------------------------------------
2279 // Do not common stores up together. They generally have to be split
2280 // back up anyways, so do not bother.
2281 uint StoreNode::cmp( const Node &n ) const {
2282 return (&n == this); // Always fail except on self
2283 }
2284
2285 //------------------------------Ideal_masked_input-----------------------------
2286 // Check for a useless mask before a partial-word store
2287 // (StoreB ... (AndI valIn conIa) )
2288 // If (conIa & mask == mask) this simplifies to
2289 // (StoreB ... (valIn) )
2290 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
2291 Node *val = in(MemNode::ValueIn);
2292 if( val->Opcode() == Op_AndI ) {
2293 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2294 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
2295 set_req(MemNode::ValueIn, val->in(1));
2296 return this;
2297 }
2298 }
2299 return NULL;
2300 }
2301
2302
2303 //------------------------------Ideal_sign_extended_input----------------------
2304 // Check for useless sign-extension before a partial-word store
2305 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) )
2306 // If (conIL == conIR && conIR <= num_bits) this simplifies to
2307 // (StoreB ... (valIn) )
2308 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) {
2309 Node *val = in(MemNode::ValueIn);
2310 if( val->Opcode() == Op_RShiftI ) {
2311 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2312 if( t && t->is_con() && (t->get_con() <= num_bits) ) {
2313 Node *shl = val->in(1);
2314 if( shl->Opcode() == Op_LShiftI ) {
2315 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int();
2316 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) {
2317 set_req(MemNode::ValueIn, shl->in(1));
2318 return this;
2319 }
2320 }
2321 }
2322 }
2323 return NULL;
2324 }
2325
2326 //------------------------------value_never_loaded-----------------------------------
2327 // Determine whether there are any possible loads of the value stored.
2328 // For simplicity, we actually check if there are any loads from the
2329 // address stored to, not just for loads of the value stored by this node.
2330 //
2331 bool StoreNode::value_never_loaded( PhaseTransform *phase) const {
2332 Node *adr = in(Address);
2333 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
2334 if (adr_oop == NULL)
2335 return false;
2336 if (!adr_oop->is_known_instance_field())
2337 return false; // if not a distinct instance, there may be aliases of the address
2338 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
2339 Node *use = adr->fast_out(i);
2340 int opc = use->Opcode();
2341 if (use->is_Load() || use->is_LoadStore()) {
2342 return false;
2343 }
2344 }
2345 return true;
2346 }
2347
2348 //=============================================================================
2349 //------------------------------Ideal------------------------------------------
2350 // If the store is from an AND mask that leaves the low bits untouched, then
2351 // we can skip the AND operation. If the store is from a sign-extension
2352 // (a left shift, then right shift) we can skip both.
2353 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
2354 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
2355 if( progress != NULL ) return progress;
2356
2357 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
2358 if( progress != NULL ) return progress;
2359
2360 // Finally check the default case
2361 return StoreNode::Ideal(phase, can_reshape);
2362 }
2363
2364 //=============================================================================
2365 //------------------------------Ideal------------------------------------------
2366 // If the store is from an AND mask that leaves the low bits untouched, then
2367 // we can skip the AND operation
2368 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
2369 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
2370 if( progress != NULL ) return progress;
2371
2372 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
2373 if( progress != NULL ) return progress;
2374
2375 // Finally check the default case
2376 return StoreNode::Ideal(phase, can_reshape);
2377 }
2378
2379 //=============================================================================
2380 //------------------------------Identity---------------------------------------
2381 Node *StoreCMNode::Identity( PhaseTransform *phase ) {
2382 // No need to card mark when storing a null ptr
2383 Node* my_store = in(MemNode::OopStore);
2384 if (my_store->is_Store()) {
2385 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) );
2386 if( t1 == TypePtr::NULL_PTR ) {
2387 return in(MemNode::Memory);
2388 }
2389 }
2390 return this;
2391 }
2392
2393 //=============================================================================
2394 //------------------------------Ideal---------------------------------------
2395 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){
2396 Node* progress = StoreNode::Ideal(phase, can_reshape);
2397 if (progress != NULL) return progress;
2398
2399 Node* my_store = in(MemNode::OopStore);
2400 if (my_store->is_MergeMem()) {
2401 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx());
2402 set_req(MemNode::OopStore, mem);
2403 return this;
2404 }
2405
2406 return NULL;
2407 }
2408
2409 //------------------------------Value-----------------------------------------
2410 const Type *StoreCMNode::Value( PhaseTransform *phase ) const {
2411 // Either input is TOP ==> the result is TOP
2412 const Type *t = phase->type( in(MemNode::Memory) );
2413 if( t == Type::TOP ) return Type::TOP;
2414 t = phase->type( in(MemNode::Address) );
2415 if( t == Type::TOP ) return Type::TOP;
2416 t = phase->type( in(MemNode::ValueIn) );
2417 if( t == Type::TOP ) return Type::TOP;
2418 // If extra input is TOP ==> the result is TOP
2419 t = phase->type( in(MemNode::OopStore) );
2420 if( t == Type::TOP ) return Type::TOP;
2421
2422 return StoreNode::Value( phase );
2423 }
2424
2425
2426 //=============================================================================
2427 //----------------------------------SCMemProjNode------------------------------
2428 const Type * SCMemProjNode::Value( PhaseTransform *phase ) const
2429 {
2430 return bottom_type();
2431 }
2432
2433 //=============================================================================
2434 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : Node(5) {
2435 init_req(MemNode::Control, c );
2436 init_req(MemNode::Memory , mem);
2437 init_req(MemNode::Address, adr);
2438 init_req(MemNode::ValueIn, val);
2439 init_req( ExpectedIn, ex );
2440 init_class_id(Class_LoadStore);
2441
2442 }
2443
2444 //=============================================================================
2445 //-------------------------------adr_type--------------------------------------
2446 // Do we Match on this edge index or not? Do not match memory
2447 const TypePtr* ClearArrayNode::adr_type() const {
2448 Node *adr = in(3);
2449 return MemNode::calculate_adr_type(adr->bottom_type());
2450 }
2451
2452 //------------------------------match_edge-------------------------------------
2453 // Do we Match on this edge index or not? Do not match memory
2454 uint ClearArrayNode::match_edge(uint idx) const {
2455 return idx > 1;
2456 }
2457
2458 //------------------------------Identity---------------------------------------
2459 // Clearing a zero length array does nothing
2460 Node *ClearArrayNode::Identity( PhaseTransform *phase ) {
2461 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
2462 }
2463
2464 //------------------------------Idealize---------------------------------------
2465 // Clearing a short array is faster with stores
2466 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape){
2467 const int unit = BytesPerLong;
2468 const TypeX* t = phase->type(in(2))->isa_intptr_t();
2469 if (!t) return NULL;
2470 if (!t->is_con()) return NULL;
2471 intptr_t raw_count = t->get_con();
2472 intptr_t size = raw_count;
2473 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
2474 // Clearing nothing uses the Identity call.
2475 // Negative clears are possible on dead ClearArrays
2476 // (see jck test stmt114.stmt11402.val).
2477 if (size <= 0 || size % unit != 0) return NULL;
2478 intptr_t count = size / unit;
2479 // Length too long; use fast hardware clear
2480 if (size > Matcher::init_array_short_size) return NULL;
2481 Node *mem = in(1);
2482 if( phase->type(mem)==Type::TOP ) return NULL;
2483 Node *adr = in(3);
2484 const Type* at = phase->type(adr);
2485 if( at==Type::TOP ) return NULL;
2486 const TypePtr* atp = at->isa_ptr();
2487 // adjust atp to be the correct array element address type
2488 if (atp == NULL) atp = TypePtr::BOTTOM;
2489 else atp = atp->add_offset(Type::OffsetBot);
2490 // Get base for derived pointer purposes
2491 if( adr->Opcode() != Op_AddP ) Unimplemented();
2492 Node *base = adr->in(1);
2493
2494 Node *zero = phase->makecon(TypeLong::ZERO);
2495 Node *off = phase->MakeConX(BytesPerLong);
2496 mem = new (phase->C, 4) StoreLNode(in(0),mem,adr,atp,zero);
2497 count--;
2498 while( count-- ) {
2499 mem = phase->transform(mem);
2500 adr = phase->transform(new (phase->C, 4) AddPNode(base,adr,off));
2501 mem = new (phase->C, 4) StoreLNode(in(0),mem,adr,atp,zero);
2502 }
2503 return mem;
2504 }
2505
2506 //----------------------------step_through----------------------------------
2507 // Return allocation input memory edge if it is different instance
2508 // or itself if it is the one we are looking for.
2509 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) {
2510 Node* n = *np;
2511 assert(n->is_ClearArray(), "sanity");
2512 intptr_t offset;
2513 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
2514 // This method is called only before Allocate nodes are expanded during
2515 // macro nodes expansion. Before that ClearArray nodes are only generated
2516 // in LibraryCallKit::generate_arraycopy() which follows allocations.
2517 assert(alloc != NULL, "should have allocation");
2518 if (alloc->_idx == instance_id) {
2519 // Can not bypass initialization of the instance we are looking for.
2520 return false;
2521 }
2522 // Otherwise skip it.
2523 InitializeNode* init = alloc->initialization();
2524 if (init != NULL)
2525 *np = init->in(TypeFunc::Memory);
2526 else
2527 *np = alloc->in(TypeFunc::Memory);
2528 return true;
2529 }
2530
2531 //----------------------------clear_memory-------------------------------------
2532 // Generate code to initialize object storage to zero.
2533 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2534 intptr_t start_offset,
2535 Node* end_offset,
2536 PhaseGVN* phase) {
2537 Compile* C = phase->C;
2538 intptr_t offset = start_offset;
2539
2540 int unit = BytesPerLong;
2541 if ((offset % unit) != 0) {
2542 Node* adr = new (C, 4) AddPNode(dest, dest, phase->MakeConX(offset));
2543 adr = phase->transform(adr);
2544 const TypePtr* atp = TypeRawPtr::BOTTOM;
2545 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT);
2546 mem = phase->transform(mem);
2547 offset += BytesPerInt;
2548 }
2549 assert((offset % unit) == 0, "");
2550
2551 // Initialize the remaining stuff, if any, with a ClearArray.
2552 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase);
2553 }
2554
2555 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2556 Node* start_offset,
2557 Node* end_offset,
2558 PhaseGVN* phase) {
2559 if (start_offset == end_offset) {
2560 // nothing to do
2561 return mem;
2562 }
2563
2564 Compile* C = phase->C;
2565 int unit = BytesPerLong;
2566 Node* zbase = start_offset;
2567 Node* zend = end_offset;
2568
2569 // Scale to the unit required by the CPU:
2570 if (!Matcher::init_array_count_is_in_bytes) {
2571 Node* shift = phase->intcon(exact_log2(unit));
2572 zbase = phase->transform( new(C,3) URShiftXNode(zbase, shift) );
2573 zend = phase->transform( new(C,3) URShiftXNode(zend, shift) );
2574 }
2575
2576 Node* zsize = phase->transform( new(C,3) SubXNode(zend, zbase) );
2577 Node* zinit = phase->zerocon((unit == BytesPerLong) ? T_LONG : T_INT);
2578
2579 // Bulk clear double-words
2580 Node* adr = phase->transform( new(C,4) AddPNode(dest, dest, start_offset) );
2581 mem = new (C, 4) ClearArrayNode(ctl, mem, zsize, adr);
2582 return phase->transform(mem);
2583 }
2584
2585 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2586 intptr_t start_offset,
2587 intptr_t end_offset,
2588 PhaseGVN* phase) {
2589 if (start_offset == end_offset) {
2590 // nothing to do
2591 return mem;
2592 }
2593
2594 Compile* C = phase->C;
2595 assert((end_offset % BytesPerInt) == 0, "odd end offset");
2596 intptr_t done_offset = end_offset;
2597 if ((done_offset % BytesPerLong) != 0) {
2598 done_offset -= BytesPerInt;
2599 }
2600 if (done_offset > start_offset) {
2601 mem = clear_memory(ctl, mem, dest,
2602 start_offset, phase->MakeConX(done_offset), phase);
2603 }
2604 if (done_offset < end_offset) { // emit the final 32-bit store
2605 Node* adr = new (C, 4) AddPNode(dest, dest, phase->MakeConX(done_offset));
2606 adr = phase->transform(adr);
2607 const TypePtr* atp = TypeRawPtr::BOTTOM;
2608 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT);
2609 mem = phase->transform(mem);
2610 done_offset += BytesPerInt;
2611 }
2612 assert(done_offset == end_offset, "");
2613 return mem;
2614 }
2615
2616 //=============================================================================
2617 // Do we match on this edge? No memory edges
2618 uint StrCompNode::match_edge(uint idx) const {
2619 return idx == 2 || idx == 3; // StrComp (Binary str1 cnt1) (Binary str2 cnt2)
2620 }
2621
2622 //------------------------------Ideal------------------------------------------
2623 // Return a node which is more "ideal" than the current node. Strip out
2624 // control copies
2625 Node *StrCompNode::Ideal(PhaseGVN *phase, bool can_reshape){
2626 return remove_dead_region(phase, can_reshape) ? this : NULL;
2627 }
2628
2629 //=============================================================================
2630 // Do we match on this edge? No memory edges
2631 uint StrEqualsNode::match_edge(uint idx) const {
2632 return idx == 2 || idx == 3; // StrEquals (Binary str1 str2) cnt
2633 }
2634
2635 //------------------------------Ideal------------------------------------------
2636 // Return a node which is more "ideal" than the current node. Strip out
2637 // control copies
2638 Node *StrEqualsNode::Ideal(PhaseGVN *phase, bool can_reshape){
2639 return remove_dead_region(phase, can_reshape) ? this : NULL;
2640 }
2641
2642 //=============================================================================
2643 // Do we match on this edge? No memory edges
2644 uint StrIndexOfNode::match_edge(uint idx) const {
2645 return idx == 2 || idx == 3; // StrIndexOf (Binary str1 cnt1) (Binary str2 cnt2)
2646 }
2647
2648 //------------------------------Ideal------------------------------------------
2649 // Return a node which is more "ideal" than the current node. Strip out
2650 // control copies
2651 Node *StrIndexOfNode::Ideal(PhaseGVN *phase, bool can_reshape){
2652 return remove_dead_region(phase, can_reshape) ? this : NULL;
2653 }
2654
2655 //=============================================================================
2656 // Do we match on this edge? No memory edges
2657 uint AryEqNode::match_edge(uint idx) const {
2658 return idx == 2 || idx == 3; // StrEquals ary1 ary2
2659 }
2660 //------------------------------Ideal------------------------------------------
2661 // Return a node which is more "ideal" than the current node. Strip out
2662 // control copies
2663 Node *AryEqNode::Ideal(PhaseGVN *phase, bool can_reshape){
2664 return remove_dead_region(phase, can_reshape) ? this : NULL;
2665 }
2666
2667 //=============================================================================
2668 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
2669 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)),
2670 _adr_type(C->get_adr_type(alias_idx))
2671 {
2672 init_class_id(Class_MemBar);
2673 Node* top = C->top();
2674 init_req(TypeFunc::I_O,top);
2675 init_req(TypeFunc::FramePtr,top);
2676 init_req(TypeFunc::ReturnAdr,top);
2677 if (precedent != NULL)
2678 init_req(TypeFunc::Parms, precedent);
2679 }
2680
2681 //------------------------------cmp--------------------------------------------
2682 uint MemBarNode::hash() const { return NO_HASH; }
2683 uint MemBarNode::cmp( const Node &n ) const {
2684 return (&n == this); // Always fail except on self
2685 }
2686
2687 //------------------------------make-------------------------------------------
2688 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
2689 int len = Precedent + (pn == NULL? 0: 1);
2690 switch (opcode) {
2691 case Op_MemBarAcquire: return new(C, len) MemBarAcquireNode(C, atp, pn);
2692 case Op_MemBarRelease: return new(C, len) MemBarReleaseNode(C, atp, pn);
2693 case Op_MemBarVolatile: return new(C, len) MemBarVolatileNode(C, atp, pn);
2694 case Op_MemBarCPUOrder: return new(C, len) MemBarCPUOrderNode(C, atp, pn);
2695 case Op_Initialize: return new(C, len) InitializeNode(C, atp, pn);
2696 default: ShouldNotReachHere(); return NULL;
2697 }
2698 }
2699
2700 //------------------------------Ideal------------------------------------------
2701 // Return a node which is more "ideal" than the current node. Strip out
2702 // control copies
2703 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2704 if (remove_dead_region(phase, can_reshape)) return this;
2705
2706 // Eliminate volatile MemBars for scalar replaced objects.
2707 if (can_reshape && req() == (Precedent+1) &&
2708 (Opcode() == Op_MemBarAcquire || Opcode() == Op_MemBarVolatile)) {
2709 // Volatile field loads and stores.
2710 Node* my_mem = in(MemBarNode::Precedent);
2711 if (my_mem != NULL && my_mem->is_Mem()) {
2712 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
2713 // Check for scalar replaced object reference.
2714 if( t_oop != NULL && t_oop->is_known_instance_field() &&
2715 t_oop->offset() != Type::OffsetBot &&
2716 t_oop->offset() != Type::OffsetTop) {
2717 // Replace MemBar projections by its inputs.
2718 PhaseIterGVN* igvn = phase->is_IterGVN();
2719 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
2720 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
2721 // Must return either the original node (now dead) or a new node
2722 // (Do not return a top here, since that would break the uniqueness of top.)
2723 return new (phase->C, 1) ConINode(TypeInt::ZERO);
2724 }
2725 }
2726 }
2727 return NULL;
2728 }
2729
2730 //------------------------------Value------------------------------------------
2731 const Type *MemBarNode::Value( PhaseTransform *phase ) const {
2732 if( !in(0) ) return Type::TOP;
2733 if( phase->type(in(0)) == Type::TOP )
2734 return Type::TOP;
2735 return TypeTuple::MEMBAR;
2736 }
2737
2738 //------------------------------match------------------------------------------
2739 // Construct projections for memory.
2740 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) {
2741 switch (proj->_con) {
2742 case TypeFunc::Control:
2743 case TypeFunc::Memory:
2744 return new (m->C, 1) MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
2745 }
2746 ShouldNotReachHere();
2747 return NULL;
2748 }
2749
2750 //===========================InitializeNode====================================
2751 // SUMMARY:
2752 // This node acts as a memory barrier on raw memory, after some raw stores.
2753 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
2754 // The Initialize can 'capture' suitably constrained stores as raw inits.
2755 // It can coalesce related raw stores into larger units (called 'tiles').
2756 // It can avoid zeroing new storage for memory units which have raw inits.
2757 // At macro-expansion, it is marked 'complete', and does not optimize further.
2758 //
2759 // EXAMPLE:
2760 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
2761 // ctl = incoming control; mem* = incoming memory
2762 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
2763 // First allocate uninitialized memory and fill in the header:
2764 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
2765 // ctl := alloc.Control; mem* := alloc.Memory*
2766 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
2767 // Then initialize to zero the non-header parts of the raw memory block:
2768 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
2769 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
2770 // After the initialize node executes, the object is ready for service:
2771 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
2772 // Suppose its body is immediately initialized as {1,2}:
2773 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
2774 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
2775 // mem.SLICE(#short[*]) := store2
2776 //
2777 // DETAILS:
2778 // An InitializeNode collects and isolates object initialization after
2779 // an AllocateNode and before the next possible safepoint. As a
2780 // memory barrier (MemBarNode), it keeps critical stores from drifting
2781 // down past any safepoint or any publication of the allocation.
2782 // Before this barrier, a newly-allocated object may have uninitialized bits.
2783 // After this barrier, it may be treated as a real oop, and GC is allowed.
2784 //
2785 // The semantics of the InitializeNode include an implicit zeroing of
2786 // the new object from object header to the end of the object.
2787 // (The object header and end are determined by the AllocateNode.)
2788 //
2789 // Certain stores may be added as direct inputs to the InitializeNode.
2790 // These stores must update raw memory, and they must be to addresses
2791 // derived from the raw address produced by AllocateNode, and with
2792 // a constant offset. They must be ordered by increasing offset.
2793 // The first one is at in(RawStores), the last at in(req()-1).
2794 // Unlike most memory operations, they are not linked in a chain,
2795 // but are displayed in parallel as users of the rawmem output of
2796 // the allocation.
2797 //
2798 // (See comments in InitializeNode::capture_store, which continue
2799 // the example given above.)
2800 //
2801 // When the associated Allocate is macro-expanded, the InitializeNode
2802 // may be rewritten to optimize collected stores. A ClearArrayNode
2803 // may also be created at that point to represent any required zeroing.
2804 // The InitializeNode is then marked 'complete', prohibiting further
2805 // capturing of nearby memory operations.
2806 //
2807 // During macro-expansion, all captured initializations which store
2808 // constant values of 32 bits or smaller are coalesced (if advantageous)
2809 // into larger 'tiles' 32 or 64 bits. This allows an object to be
2810 // initialized in fewer memory operations. Memory words which are
2811 // covered by neither tiles nor non-constant stores are pre-zeroed
2812 // by explicit stores of zero. (The code shape happens to do all
2813 // zeroing first, then all other stores, with both sequences occurring
2814 // in order of ascending offsets.)
2815 //
2816 // Alternatively, code may be inserted between an AllocateNode and its
2817 // InitializeNode, to perform arbitrary initialization of the new object.
2818 // E.g., the object copying intrinsics insert complex data transfers here.
2819 // The initialization must then be marked as 'complete' disable the
2820 // built-in zeroing semantics and the collection of initializing stores.
2821 //
2822 // While an InitializeNode is incomplete, reads from the memory state
2823 // produced by it are optimizable if they match the control edge and
2824 // new oop address associated with the allocation/initialization.
2825 // They return a stored value (if the offset matches) or else zero.
2826 // A write to the memory state, if it matches control and address,
2827 // and if it is to a constant offset, may be 'captured' by the
2828 // InitializeNode. It is cloned as a raw memory operation and rewired
2829 // inside the initialization, to the raw oop produced by the allocation.
2830 // Operations on addresses which are provably distinct (e.g., to
2831 // other AllocateNodes) are allowed to bypass the initialization.
2832 //
2833 // The effect of all this is to consolidate object initialization
2834 // (both arrays and non-arrays, both piecewise and bulk) into a
2835 // single location, where it can be optimized as a unit.
2836 //
2837 // Only stores with an offset less than TrackedInitializationLimit words
2838 // will be considered for capture by an InitializeNode. This puts a
2839 // reasonable limit on the complexity of optimized initializations.
2840
2841 //---------------------------InitializeNode------------------------------------
2842 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
2843 : _is_complete(false),
2844 MemBarNode(C, adr_type, rawoop)
2845 {
2846 init_class_id(Class_Initialize);
2847
2848 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
2849 assert(in(RawAddress) == rawoop, "proper init");
2850 // Note: allocation() can be NULL, for secondary initialization barriers
2851 }
2852
2853 // Since this node is not matched, it will be processed by the
2854 // register allocator. Declare that there are no constraints
2855 // on the allocation of the RawAddress edge.
2856 const RegMask &InitializeNode::in_RegMask(uint idx) const {
2857 // This edge should be set to top, by the set_complete. But be conservative.
2858 if (idx == InitializeNode::RawAddress)
2859 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
2860 return RegMask::Empty;
2861 }
2862
2863 Node* InitializeNode::memory(uint alias_idx) {
2864 Node* mem = in(Memory);
2865 if (mem->is_MergeMem()) {
2866 return mem->as_MergeMem()->memory_at(alias_idx);
2867 } else {
2868 // incoming raw memory is not split
2869 return mem;
2870 }
2871 }
2872
2873 bool InitializeNode::is_non_zero() {
2874 if (is_complete()) return false;
2875 remove_extra_zeroes();
2876 return (req() > RawStores);
2877 }
2878
2879 void InitializeNode::set_complete(PhaseGVN* phase) {
2880 assert(!is_complete(), "caller responsibility");
2881 _is_complete = true;
2882
2883 // After this node is complete, it contains a bunch of
2884 // raw-memory initializations. There is no need for
2885 // it to have anything to do with non-raw memory effects.
2886 // Therefore, tell all non-raw users to re-optimize themselves,
2887 // after skipping the memory effects of this initialization.
2888 PhaseIterGVN* igvn = phase->is_IterGVN();
2889 if (igvn) igvn->add_users_to_worklist(this);
2890 }
2891
2892 // convenience function
2893 // return false if the init contains any stores already
2894 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
2895 InitializeNode* init = initialization();
2896 if (init == NULL || init->is_complete()) return false;
2897 init->remove_extra_zeroes();
2898 // for now, if this allocation has already collected any inits, bail:
2899 if (init->is_non_zero()) return false;
2900 init->set_complete(phase);
2901 return true;
2902 }
2903
2904 void InitializeNode::remove_extra_zeroes() {
2905 if (req() == RawStores) return;
2906 Node* zmem = zero_memory();
2907 uint fill = RawStores;
2908 for (uint i = fill; i < req(); i++) {
2909 Node* n = in(i);
2910 if (n->is_top() || n == zmem) continue; // skip
2911 if (fill < i) set_req(fill, n); // compact
2912 ++fill;
2913 }
2914 // delete any empty spaces created:
2915 while (fill < req()) {
2916 del_req(fill);
2917 }
2918 }
2919
2920 // Helper for remembering which stores go with which offsets.
2921 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) {
2922 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
2923 intptr_t offset = -1;
2924 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
2925 phase, offset);
2926 if (base == NULL) return -1; // something is dead,
2927 if (offset < 0) return -1; // dead, dead
2928 return offset;
2929 }
2930
2931 // Helper for proving that an initialization expression is
2932 // "simple enough" to be folded into an object initialization.
2933 // Attempts to prove that a store's initial value 'n' can be captured
2934 // within the initialization without creating a vicious cycle, such as:
2935 // { Foo p = new Foo(); p.next = p; }
2936 // True for constants and parameters and small combinations thereof.
2937 bool InitializeNode::detect_init_independence(Node* n,
2938 bool st_is_pinned,
2939 int& count) {
2940 if (n == NULL) return true; // (can this really happen?)
2941 if (n->is_Proj()) n = n->in(0);
2942 if (n == this) return false; // found a cycle
2943 if (n->is_Con()) return true;
2944 if (n->is_Start()) return true; // params, etc., are OK
2945 if (n->is_Root()) return true; // even better
2946
2947 Node* ctl = n->in(0);
2948 if (ctl != NULL && !ctl->is_top()) {
2949 if (ctl->is_Proj()) ctl = ctl->in(0);
2950 if (ctl == this) return false;
2951
2952 // If we already know that the enclosing memory op is pinned right after
2953 // the init, then any control flow that the store has picked up
2954 // must have preceded the init, or else be equal to the init.
2955 // Even after loop optimizations (which might change control edges)
2956 // a store is never pinned *before* the availability of its inputs.
2957 if (!MemNode::all_controls_dominate(n, this))
2958 return false; // failed to prove a good control
2959
2960 }
2961
2962 // Check data edges for possible dependencies on 'this'.
2963 if ((count += 1) > 20) return false; // complexity limit
2964 for (uint i = 1; i < n->req(); i++) {
2965 Node* m = n->in(i);
2966 if (m == NULL || m == n || m->is_top()) continue;
2967 uint first_i = n->find_edge(m);
2968 if (i != first_i) continue; // process duplicate edge just once
2969 if (!detect_init_independence(m, st_is_pinned, count)) {
2970 return false;
2971 }
2972 }
2973
2974 return true;
2975 }
2976
2977 // Here are all the checks a Store must pass before it can be moved into
2978 // an initialization. Returns zero if a check fails.
2979 // On success, returns the (constant) offset to which the store applies,
2980 // within the initialized memory.
2981 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase) {
2982 const int FAIL = 0;
2983 if (st->req() != MemNode::ValueIn + 1)
2984 return FAIL; // an inscrutable StoreNode (card mark?)
2985 Node* ctl = st->in(MemNode::Control);
2986 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this))
2987 return FAIL; // must be unconditional after the initialization
2988 Node* mem = st->in(MemNode::Memory);
2989 if (!(mem->is_Proj() && mem->in(0) == this))
2990 return FAIL; // must not be preceded by other stores
2991 Node* adr = st->in(MemNode::Address);
2992 intptr_t offset;
2993 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
2994 if (alloc == NULL)
2995 return FAIL; // inscrutable address
2996 if (alloc != allocation())
2997 return FAIL; // wrong allocation! (store needs to float up)
2998 Node* val = st->in(MemNode::ValueIn);
2999 int complexity_count = 0;
3000 if (!detect_init_independence(val, true, complexity_count))
3001 return FAIL; // stored value must be 'simple enough'
3002
3003 return offset; // success
3004 }
3005
3006 // Find the captured store in(i) which corresponds to the range
3007 // [start..start+size) in the initialized object.
3008 // If there is one, return its index i. If there isn't, return the
3009 // negative of the index where it should be inserted.
3010 // Return 0 if the queried range overlaps an initialization boundary
3011 // or if dead code is encountered.
3012 // If size_in_bytes is zero, do not bother with overlap checks.
3013 int InitializeNode::captured_store_insertion_point(intptr_t start,
3014 int size_in_bytes,
3015 PhaseTransform* phase) {
3016 const int FAIL = 0, MAX_STORE = BytesPerLong;
3017
3018 if (is_complete())
3019 return FAIL; // arraycopy got here first; punt
3020
3021 assert(allocation() != NULL, "must be present");
3022
3023 // no negatives, no header fields:
3024 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
3025
3026 // after a certain size, we bail out on tracking all the stores:
3027 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3028 if (start >= ti_limit) return FAIL;
3029
3030 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
3031 if (i >= limit) return -(int)i; // not found; here is where to put it
3032
3033 Node* st = in(i);
3034 intptr_t st_off = get_store_offset(st, phase);
3035 if (st_off < 0) {
3036 if (st != zero_memory()) {
3037 return FAIL; // bail out if there is dead garbage
3038 }
3039 } else if (st_off > start) {
3040 // ...we are done, since stores are ordered
3041 if (st_off < start + size_in_bytes) {
3042 return FAIL; // the next store overlaps
3043 }
3044 return -(int)i; // not found; here is where to put it
3045 } else if (st_off < start) {
3046 if (size_in_bytes != 0 &&
3047 start < st_off + MAX_STORE &&
3048 start < st_off + st->as_Store()->memory_size()) {
3049 return FAIL; // the previous store overlaps
3050 }
3051 } else {
3052 if (size_in_bytes != 0 &&
3053 st->as_Store()->memory_size() != size_in_bytes) {
3054 return FAIL; // mismatched store size
3055 }
3056 return i;
3057 }
3058
3059 ++i;
3060 }
3061 }
3062
3063 // Look for a captured store which initializes at the offset 'start'
3064 // with the given size. If there is no such store, and no other
3065 // initialization interferes, then return zero_memory (the memory
3066 // projection of the AllocateNode).
3067 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
3068 PhaseTransform* phase) {
3069 assert(stores_are_sane(phase), "");
3070 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3071 if (i == 0) {
3072 return NULL; // something is dead
3073 } else if (i < 0) {
3074 return zero_memory(); // just primordial zero bits here
3075 } else {
3076 Node* st = in(i); // here is the store at this position
3077 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
3078 return st;
3079 }
3080 }
3081
3082 // Create, as a raw pointer, an address within my new object at 'offset'.
3083 Node* InitializeNode::make_raw_address(intptr_t offset,
3084 PhaseTransform* phase) {
3085 Node* addr = in(RawAddress);
3086 if (offset != 0) {
3087 Compile* C = phase->C;
3088 addr = phase->transform( new (C, 4) AddPNode(C->top(), addr,
3089 phase->MakeConX(offset)) );
3090 }
3091 return addr;
3092 }
3093
3094 // Clone the given store, converting it into a raw store
3095 // initializing a field or element of my new object.
3096 // Caller is responsible for retiring the original store,
3097 // with subsume_node or the like.
3098 //
3099 // From the example above InitializeNode::InitializeNode,
3100 // here are the old stores to be captured:
3101 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3102 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3103 //
3104 // Here is the changed code; note the extra edges on init:
3105 // alloc = (Allocate ...)
3106 // rawoop = alloc.RawAddress
3107 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
3108 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
3109 // init = (Initialize alloc.Control alloc.Memory rawoop
3110 // rawstore1 rawstore2)
3111 //
3112 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
3113 PhaseTransform* phase) {
3114 assert(stores_are_sane(phase), "");
3115
3116 if (start < 0) return NULL;
3117 assert(can_capture_store(st, phase) == start, "sanity");
3118
3119 Compile* C = phase->C;
3120 int size_in_bytes = st->memory_size();
3121 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3122 if (i == 0) return NULL; // bail out
3123 Node* prev_mem = NULL; // raw memory for the captured store
3124 if (i > 0) {
3125 prev_mem = in(i); // there is a pre-existing store under this one
3126 set_req(i, C->top()); // temporarily disconnect it
3127 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
3128 } else {
3129 i = -i; // no pre-existing store
3130 prev_mem = zero_memory(); // a slice of the newly allocated object
3131 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
3132 set_req(--i, C->top()); // reuse this edge; it has been folded away
3133 else
3134 ins_req(i, C->top()); // build a new edge
3135 }
3136 Node* new_st = st->clone();
3137 new_st->set_req(MemNode::Control, in(Control));
3138 new_st->set_req(MemNode::Memory, prev_mem);
3139 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
3140 new_st = phase->transform(new_st);
3141
3142 // At this point, new_st might have swallowed a pre-existing store
3143 // at the same offset, or perhaps new_st might have disappeared,
3144 // if it redundantly stored the same value (or zero to fresh memory).
3145
3146 // In any case, wire it in:
3147 set_req(i, new_st);
3148
3149 // The caller may now kill the old guy.
3150 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
3151 assert(check_st == new_st || check_st == NULL, "must be findable");
3152 assert(!is_complete(), "");
3153 return new_st;
3154 }
3155
3156 static bool store_constant(jlong* tiles, int num_tiles,
3157 intptr_t st_off, int st_size,
3158 jlong con) {
3159 if ((st_off & (st_size-1)) != 0)
3160 return false; // strange store offset (assume size==2**N)
3161 address addr = (address)tiles + st_off;
3162 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
3163 switch (st_size) {
3164 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
3165 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
3166 case sizeof(jint): *(jint*) addr = (jint) con; break;
3167 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
3168 default: return false; // strange store size (detect size!=2**N here)
3169 }
3170 return true; // return success to caller
3171 }
3172
3173 // Coalesce subword constants into int constants and possibly
3174 // into long constants. The goal, if the CPU permits,
3175 // is to initialize the object with a small number of 64-bit tiles.
3176 // Also, convert floating-point constants to bit patterns.
3177 // Non-constants are not relevant to this pass.
3178 //
3179 // In terms of the running example on InitializeNode::InitializeNode
3180 // and InitializeNode::capture_store, here is the transformation
3181 // of rawstore1 and rawstore2 into rawstore12:
3182 // alloc = (Allocate ...)
3183 // rawoop = alloc.RawAddress
3184 // tile12 = 0x00010002
3185 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
3186 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
3187 //
3188 void
3189 InitializeNode::coalesce_subword_stores(intptr_t header_size,
3190 Node* size_in_bytes,
3191 PhaseGVN* phase) {
3192 Compile* C = phase->C;
3193
3194 assert(stores_are_sane(phase), "");
3195 // Note: After this pass, they are not completely sane,
3196 // since there may be some overlaps.
3197
3198 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
3199
3200 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3201 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
3202 size_limit = MIN2(size_limit, ti_limit);
3203 size_limit = align_size_up(size_limit, BytesPerLong);
3204 int num_tiles = size_limit / BytesPerLong;
3205
3206 // allocate space for the tile map:
3207 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
3208 jlong tiles_buf[small_len];
3209 Node* nodes_buf[small_len];
3210 jlong inits_buf[small_len];
3211 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
3212 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3213 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
3214 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
3215 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
3216 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3217 // tiles: exact bitwise model of all primitive constants
3218 // nodes: last constant-storing node subsumed into the tiles model
3219 // inits: which bytes (in each tile) are touched by any initializations
3220
3221 //// Pass A: Fill in the tile model with any relevant stores.
3222
3223 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
3224 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
3225 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
3226 Node* zmem = zero_memory(); // initially zero memory state
3227 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3228 Node* st = in(i);
3229 intptr_t st_off = get_store_offset(st, phase);
3230
3231 // Figure out the store's offset and constant value:
3232 if (st_off < header_size) continue; //skip (ignore header)
3233 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
3234 int st_size = st->as_Store()->memory_size();
3235 if (st_off + st_size > size_limit) break;
3236
3237 // Record which bytes are touched, whether by constant or not.
3238 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
3239 continue; // skip (strange store size)
3240
3241 const Type* val = phase->type(st->in(MemNode::ValueIn));
3242 if (!val->singleton()) continue; //skip (non-con store)
3243 BasicType type = val->basic_type();
3244
3245 jlong con = 0;
3246 switch (type) {
3247 case T_INT: con = val->is_int()->get_con(); break;
3248 case T_LONG: con = val->is_long()->get_con(); break;
3249 case T_FLOAT: con = jint_cast(val->getf()); break;
3250 case T_DOUBLE: con = jlong_cast(val->getd()); break;
3251 default: continue; //skip (odd store type)
3252 }
3253
3254 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
3255 st->Opcode() == Op_StoreL) {
3256 continue; // This StoreL is already optimal.
3257 }
3258
3259 // Store down the constant.
3260 store_constant(tiles, num_tiles, st_off, st_size, con);
3261
3262 intptr_t j = st_off >> LogBytesPerLong;
3263
3264 if (type == T_INT && st_size == BytesPerInt
3265 && (st_off & BytesPerInt) == BytesPerInt) {
3266 jlong lcon = tiles[j];
3267 if (!Matcher::isSimpleConstant64(lcon) &&
3268 st->Opcode() == Op_StoreI) {
3269 // This StoreI is already optimal by itself.
3270 jint* intcon = (jint*) &tiles[j];
3271 intcon[1] = 0; // undo the store_constant()
3272
3273 // If the previous store is also optimal by itself, back up and
3274 // undo the action of the previous loop iteration... if we can.
3275 // But if we can't, just let the previous half take care of itself.
3276 st = nodes[j];
3277 st_off -= BytesPerInt;
3278 con = intcon[0];
3279 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) {
3280 assert(st_off >= header_size, "still ignoring header");
3281 assert(get_store_offset(st, phase) == st_off, "must be");
3282 assert(in(i-1) == zmem, "must be");
3283 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
3284 assert(con == tcon->is_int()->get_con(), "must be");
3285 // Undo the effects of the previous loop trip, which swallowed st:
3286 intcon[0] = 0; // undo store_constant()
3287 set_req(i-1, st); // undo set_req(i, zmem)
3288 nodes[j] = NULL; // undo nodes[j] = st
3289 --old_subword; // undo ++old_subword
3290 }
3291 continue; // This StoreI is already optimal.
3292 }
3293 }
3294
3295 // This store is not needed.
3296 set_req(i, zmem);
3297 nodes[j] = st; // record for the moment
3298 if (st_size < BytesPerLong) // something has changed
3299 ++old_subword; // includes int/float, but who's counting...
3300 else ++old_long;
3301 }
3302
3303 if ((old_subword + old_long) == 0)
3304 return; // nothing more to do
3305
3306 //// Pass B: Convert any non-zero tiles into optimal constant stores.
3307 // Be sure to insert them before overlapping non-constant stores.
3308 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
3309 for (int j = 0; j < num_tiles; j++) {
3310 jlong con = tiles[j];
3311 jlong init = inits[j];
3312 if (con == 0) continue;
3313 jint con0, con1; // split the constant, address-wise
3314 jint init0, init1; // split the init map, address-wise
3315 { union { jlong con; jint intcon[2]; } u;
3316 u.con = con;
3317 con0 = u.intcon[0];
3318 con1 = u.intcon[1];
3319 u.con = init;
3320 init0 = u.intcon[0];
3321 init1 = u.intcon[1];
3322 }
3323
3324 Node* old = nodes[j];
3325 assert(old != NULL, "need the prior store");
3326 intptr_t offset = (j * BytesPerLong);
3327
3328 bool split = !Matcher::isSimpleConstant64(con);
3329
3330 if (offset < header_size) {
3331 assert(offset + BytesPerInt >= header_size, "second int counts");
3332 assert(*(jint*)&tiles[j] == 0, "junk in header");
3333 split = true; // only the second word counts
3334 // Example: int a[] = { 42 ... }
3335 } else if (con0 == 0 && init0 == -1) {
3336 split = true; // first word is covered by full inits
3337 // Example: int a[] = { ... foo(), 42 ... }
3338 } else if (con1 == 0 && init1 == -1) {
3339 split = true; // second word is covered by full inits
3340 // Example: int a[] = { ... 42, foo() ... }
3341 }
3342
3343 // Here's a case where init0 is neither 0 nor -1:
3344 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
3345 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
3346 // In this case the tile is not split; it is (jlong)42.
3347 // The big tile is stored down, and then the foo() value is inserted.
3348 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
3349
3350 Node* ctl = old->in(MemNode::Control);
3351 Node* adr = make_raw_address(offset, phase);
3352 const TypePtr* atp = TypeRawPtr::BOTTOM;
3353
3354 // One or two coalesced stores to plop down.
3355 Node* st[2];
3356 intptr_t off[2];
3357 int nst = 0;
3358 if (!split) {
3359 ++new_long;
3360 off[nst] = offset;
3361 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3362 phase->longcon(con), T_LONG);
3363 } else {
3364 // Omit either if it is a zero.
3365 if (con0 != 0) {
3366 ++new_int;
3367 off[nst] = offset;
3368 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3369 phase->intcon(con0), T_INT);
3370 }
3371 if (con1 != 0) {
3372 ++new_int;
3373 offset += BytesPerInt;
3374 adr = make_raw_address(offset, phase);
3375 off[nst] = offset;
3376 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3377 phase->intcon(con1), T_INT);
3378 }
3379 }
3380
3381 // Insert second store first, then the first before the second.
3382 // Insert each one just before any overlapping non-constant stores.
3383 while (nst > 0) {
3384 Node* st1 = st[--nst];
3385 C->copy_node_notes_to(st1, old);
3386 st1 = phase->transform(st1);
3387 offset = off[nst];
3388 assert(offset >= header_size, "do not smash header");
3389 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
3390 guarantee(ins_idx != 0, "must re-insert constant store");
3391 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
3392 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
3393 set_req(--ins_idx, st1);
3394 else
3395 ins_req(ins_idx, st1);
3396 }
3397 }
3398
3399 if (PrintCompilation && WizardMode)
3400 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
3401 old_subword, old_long, new_int, new_long);
3402 if (C->log() != NULL)
3403 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
3404 old_subword, old_long, new_int, new_long);
3405
3406 // Clean up any remaining occurrences of zmem:
3407 remove_extra_zeroes();
3408 }
3409
3410 // Explore forward from in(start) to find the first fully initialized
3411 // word, and return its offset. Skip groups of subword stores which
3412 // together initialize full words. If in(start) is itself part of a
3413 // fully initialized word, return the offset of in(start). If there
3414 // are no following full-word stores, or if something is fishy, return
3415 // a negative value.
3416 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
3417 int int_map = 0;
3418 intptr_t int_map_off = 0;
3419 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
3420
3421 for (uint i = start, limit = req(); i < limit; i++) {
3422 Node* st = in(i);
3423
3424 intptr_t st_off = get_store_offset(st, phase);
3425 if (st_off < 0) break; // return conservative answer
3426
3427 int st_size = st->as_Store()->memory_size();
3428 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
3429 return st_off; // we found a complete word init
3430 }
3431
3432 // update the map:
3433
3434 intptr_t this_int_off = align_size_down(st_off, BytesPerInt);
3435 if (this_int_off != int_map_off) {
3436 // reset the map:
3437 int_map = 0;
3438 int_map_off = this_int_off;
3439 }
3440
3441 int subword_off = st_off - this_int_off;
3442 int_map |= right_n_bits(st_size) << subword_off;
3443 if ((int_map & FULL_MAP) == FULL_MAP) {
3444 return this_int_off; // we found a complete word init
3445 }
3446
3447 // Did this store hit or cross the word boundary?
3448 intptr_t next_int_off = align_size_down(st_off + st_size, BytesPerInt);
3449 if (next_int_off == this_int_off + BytesPerInt) {
3450 // We passed the current int, without fully initializing it.
3451 int_map_off = next_int_off;
3452 int_map >>= BytesPerInt;
3453 } else if (next_int_off > this_int_off + BytesPerInt) {
3454 // We passed the current and next int.
3455 return this_int_off + BytesPerInt;
3456 }
3457 }
3458
3459 return -1;
3460 }
3461
3462
3463 // Called when the associated AllocateNode is expanded into CFG.
3464 // At this point, we may perform additional optimizations.
3465 // Linearize the stores by ascending offset, to make memory
3466 // activity as coherent as possible.
3467 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
3468 intptr_t header_size,
3469 Node* size_in_bytes,
3470 PhaseGVN* phase) {
3471 assert(!is_complete(), "not already complete");
3472 assert(stores_are_sane(phase), "");
3473 assert(allocation() != NULL, "must be present");
3474
3475 remove_extra_zeroes();
3476
3477 if (ReduceFieldZeroing || ReduceBulkZeroing)
3478 // reduce instruction count for common initialization patterns
3479 coalesce_subword_stores(header_size, size_in_bytes, phase);
3480
3481 Node* zmem = zero_memory(); // initially zero memory state
3482 Node* inits = zmem; // accumulating a linearized chain of inits
3483 #ifdef ASSERT
3484 intptr_t first_offset = allocation()->minimum_header_size();
3485 intptr_t last_init_off = first_offset; // previous init offset
3486 intptr_t last_init_end = first_offset; // previous init offset+size
3487 intptr_t last_tile_end = first_offset; // previous tile offset+size
3488 #endif
3489 intptr_t zeroes_done = header_size;
3490
3491 bool do_zeroing = true; // we might give up if inits are very sparse
3492 int big_init_gaps = 0; // how many large gaps have we seen?
3493
3494 if (ZeroTLAB) do_zeroing = false;
3495 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
3496
3497 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3498 Node* st = in(i);
3499 intptr_t st_off = get_store_offset(st, phase);
3500 if (st_off < 0)
3501 break; // unknown junk in the inits
3502 if (st->in(MemNode::Memory) != zmem)
3503 break; // complicated store chains somehow in list
3504
3505 int st_size = st->as_Store()->memory_size();
3506 intptr_t next_init_off = st_off + st_size;
3507
3508 if (do_zeroing && zeroes_done < next_init_off) {
3509 // See if this store needs a zero before it or under it.
3510 intptr_t zeroes_needed = st_off;
3511
3512 if (st_size < BytesPerInt) {
3513 // Look for subword stores which only partially initialize words.
3514 // If we find some, we must lay down some word-level zeroes first,
3515 // underneath the subword stores.
3516 //
3517 // Examples:
3518 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
3519 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
3520 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
3521 //
3522 // Note: coalesce_subword_stores may have already done this,
3523 // if it was prompted by constant non-zero subword initializers.
3524 // But this case can still arise with non-constant stores.
3525
3526 intptr_t next_full_store = find_next_fullword_store(i, phase);
3527
3528 // In the examples above:
3529 // in(i) p q r s x y z
3530 // st_off 12 13 14 15 12 13 14
3531 // st_size 1 1 1 1 1 1 1
3532 // next_full_s. 12 16 16 16 16 16 16
3533 // z's_done 12 16 16 16 12 16 12
3534 // z's_needed 12 16 16 16 16 16 16
3535 // zsize 0 0 0 0 4 0 4
3536 if (next_full_store < 0) {
3537 // Conservative tack: Zero to end of current word.
3538 zeroes_needed = align_size_up(zeroes_needed, BytesPerInt);
3539 } else {
3540 // Zero to beginning of next fully initialized word.
3541 // Or, don't zero at all, if we are already in that word.
3542 assert(next_full_store >= zeroes_needed, "must go forward");
3543 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
3544 zeroes_needed = next_full_store;
3545 }
3546 }
3547
3548 if (zeroes_needed > zeroes_done) {
3549 intptr_t zsize = zeroes_needed - zeroes_done;
3550 // Do some incremental zeroing on rawmem, in parallel with inits.
3551 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3552 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3553 zeroes_done, zeroes_needed,
3554 phase);
3555 zeroes_done = zeroes_needed;
3556 if (zsize > Matcher::init_array_short_size && ++big_init_gaps > 2)
3557 do_zeroing = false; // leave the hole, next time
3558 }
3559 }
3560
3561 // Collect the store and move on:
3562 st->set_req(MemNode::Memory, inits);
3563 inits = st; // put it on the linearized chain
3564 set_req(i, zmem); // unhook from previous position
3565
3566 if (zeroes_done == st_off)
3567 zeroes_done = next_init_off;
3568
3569 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
3570
3571 #ifdef ASSERT
3572 // Various order invariants. Weaker than stores_are_sane because
3573 // a large constant tile can be filled in by smaller non-constant stores.
3574 assert(st_off >= last_init_off, "inits do not reverse");
3575 last_init_off = st_off;
3576 const Type* val = NULL;
3577 if (st_size >= BytesPerInt &&
3578 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
3579 (int)val->basic_type() < (int)T_OBJECT) {
3580 assert(st_off >= last_tile_end, "tiles do not overlap");
3581 assert(st_off >= last_init_end, "tiles do not overwrite inits");
3582 last_tile_end = MAX2(last_tile_end, next_init_off);
3583 } else {
3584 intptr_t st_tile_end = align_size_up(next_init_off, BytesPerLong);
3585 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
3586 assert(st_off >= last_init_end, "inits do not overlap");
3587 last_init_end = next_init_off; // it's a non-tile
3588 }
3589 #endif //ASSERT
3590 }
3591
3592 remove_extra_zeroes(); // clear out all the zmems left over
3593 add_req(inits);
3594
3595 if (!ZeroTLAB) {
3596 // If anything remains to be zeroed, zero it all now.
3597 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3598 // if it is the last unused 4 bytes of an instance, forget about it
3599 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
3600 if (zeroes_done + BytesPerLong >= size_limit) {
3601 assert(allocation() != NULL, "");
3602 if (allocation()->Opcode() == Op_Allocate) {
3603 Node* klass_node = allocation()->in(AllocateNode::KlassNode);
3604 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass();
3605 if (zeroes_done == k->layout_helper())
3606 zeroes_done = size_limit;
3607 }
3608 }
3609 if (zeroes_done < size_limit) {
3610 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3611 zeroes_done, size_in_bytes, phase);
3612 }
3613 }
3614
3615 set_complete(phase);
3616 return rawmem;
3617 }
3618
3619
3620 #ifdef ASSERT
3621 bool InitializeNode::stores_are_sane(PhaseTransform* phase) {
3622 if (is_complete())
3623 return true; // stores could be anything at this point
3624 assert(allocation() != NULL, "must be present");
3625 intptr_t last_off = allocation()->minimum_header_size();
3626 for (uint i = InitializeNode::RawStores; i < req(); i++) {
3627 Node* st = in(i);
3628 intptr_t st_off = get_store_offset(st, phase);
3629 if (st_off < 0) continue; // ignore dead garbage
3630 if (last_off > st_off) {
3631 tty->print_cr("*** bad store offset at %d: %d > %d", i, last_off, st_off);
3632 this->dump(2);
3633 assert(false, "ascending store offsets");
3634 return false;
3635 }
3636 last_off = st_off + st->as_Store()->memory_size();
3637 }
3638 return true;
3639 }
3640 #endif //ASSERT
3641
3642
3643
3644
3645 //============================MergeMemNode=====================================
3646 //
3647 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
3648 // contributing store or call operations. Each contributor provides the memory
3649 // state for a particular "alias type" (see Compile::alias_type). For example,
3650 // if a MergeMem has an input X for alias category #6, then any memory reference
3651 // to alias category #6 may use X as its memory state input, as an exact equivalent
3652 // to using the MergeMem as a whole.
3653 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
3654 //
3655 // (Here, the <N> notation gives the index of the relevant adr_type.)
3656 //
3657 // In one special case (and more cases in the future), alias categories overlap.
3658 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
3659 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
3660 // it is exactly equivalent to that state W:
3661 // MergeMem(<Bot>: W) <==> W
3662 //
3663 // Usually, the merge has more than one input. In that case, where inputs
3664 // overlap (i.e., one is Bot), the narrower alias type determines the memory
3665 // state for that type, and the wider alias type (Bot) fills in everywhere else:
3666 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
3667 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
3668 //
3669 // A merge can take a "wide" memory state as one of its narrow inputs.
3670 // This simply means that the merge observes out only the relevant parts of
3671 // the wide input. That is, wide memory states arriving at narrow merge inputs
3672 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
3673 //
3674 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
3675 // and that memory slices "leak through":
3676 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
3677 //
3678 // But, in such a cascade, repeated memory slices can "block the leak":
3679 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
3680 //
3681 // In the last example, Y is not part of the combined memory state of the
3682 // outermost MergeMem. The system must, of course, prevent unschedulable
3683 // memory states from arising, so you can be sure that the state Y is somehow
3684 // a precursor to state Y'.
3685 //
3686 //
3687 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
3688 // of each MergeMemNode array are exactly the numerical alias indexes, including
3689 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
3690 // Compile::alias_type (and kin) produce and manage these indexes.
3691 //
3692 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
3693 // (Note that this provides quick access to the top node inside MergeMem methods,
3694 // without the need to reach out via TLS to Compile::current.)
3695 //
3696 // As a consequence of what was just described, a MergeMem that represents a full
3697 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
3698 // containing all alias categories.
3699 //
3700 // MergeMem nodes never (?) have control inputs, so in(0) is NULL.
3701 //
3702 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
3703 // a memory state for the alias type <N>, or else the top node, meaning that
3704 // there is no particular input for that alias type. Note that the length of
3705 // a MergeMem is variable, and may be extended at any time to accommodate new
3706 // memory states at larger alias indexes. When merges grow, they are of course
3707 // filled with "top" in the unused in() positions.
3708 //
3709 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
3710 // (Top was chosen because it works smoothly with passes like GCM.)
3711 //
3712 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
3713 // the type of random VM bits like TLS references.) Since it is always the
3714 // first non-Bot memory slice, some low-level loops use it to initialize an
3715 // index variable: for (i = AliasIdxRaw; i < req(); i++).
3716 //
3717 //
3718 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
3719 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
3720 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
3721 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
3722 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
3723 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
3724 //
3725 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
3726 // really that different from the other memory inputs. An abbreviation called
3727 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
3728 //
3729 //
3730 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
3731 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
3732 // that "emerges though" the base memory will be marked as excluding the alias types
3733 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
3734 //
3735 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
3736 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
3737 //
3738 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
3739 // (It is currently unimplemented.) As you can see, the resulting merge is
3740 // actually a disjoint union of memory states, rather than an overlay.
3741 //
3742
3743 //------------------------------MergeMemNode-----------------------------------
3744 Node* MergeMemNode::make_empty_memory() {
3745 Node* empty_memory = (Node*) Compile::current()->top();
3746 assert(empty_memory->is_top(), "correct sentinel identity");
3747 return empty_memory;
3748 }
3749
3750 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
3751 init_class_id(Class_MergeMem);
3752 // all inputs are nullified in Node::Node(int)
3753 // set_input(0, NULL); // no control input
3754
3755 // Initialize the edges uniformly to top, for starters.
3756 Node* empty_mem = make_empty_memory();
3757 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
3758 init_req(i,empty_mem);
3759 }
3760 assert(empty_memory() == empty_mem, "");
3761
3762 if( new_base != NULL && new_base->is_MergeMem() ) {
3763 MergeMemNode* mdef = new_base->as_MergeMem();
3764 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
3765 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
3766 mms.set_memory(mms.memory2());
3767 }
3768 assert(base_memory() == mdef->base_memory(), "");
3769 } else {
3770 set_base_memory(new_base);
3771 }
3772 }
3773
3774 // Make a new, untransformed MergeMem with the same base as 'mem'.
3775 // If mem is itself a MergeMem, populate the result with the same edges.
3776 MergeMemNode* MergeMemNode::make(Compile* C, Node* mem) {
3777 return new(C, 1+Compile::AliasIdxRaw) MergeMemNode(mem);
3778 }
3779
3780 //------------------------------cmp--------------------------------------------
3781 uint MergeMemNode::hash() const { return NO_HASH; }
3782 uint MergeMemNode::cmp( const Node &n ) const {
3783 return (&n == this); // Always fail except on self
3784 }
3785
3786 //------------------------------Identity---------------------------------------
3787 Node* MergeMemNode::Identity(PhaseTransform *phase) {
3788 // Identity if this merge point does not record any interesting memory
3789 // disambiguations.
3790 Node* base_mem = base_memory();
3791 Node* empty_mem = empty_memory();
3792 if (base_mem != empty_mem) { // Memory path is not dead?
3793 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3794 Node* mem = in(i);
3795 if (mem != empty_mem && mem != base_mem) {
3796 return this; // Many memory splits; no change
3797 }
3798 }
3799 }
3800 return base_mem; // No memory splits; ID on the one true input
3801 }
3802
3803 //------------------------------Ideal------------------------------------------
3804 // This method is invoked recursively on chains of MergeMem nodes
3805 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3806 // Remove chain'd MergeMems
3807 //
3808 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
3809 // relative to the "in(Bot)". Since we are patching both at the same time,
3810 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
3811 // but rewrite each "in(i)" relative to the new "in(Bot)".
3812 Node *progress = NULL;
3813
3814
3815 Node* old_base = base_memory();
3816 Node* empty_mem = empty_memory();
3817 if (old_base == empty_mem)
3818 return NULL; // Dead memory path.
3819
3820 MergeMemNode* old_mbase;
3821 if (old_base != NULL && old_base->is_MergeMem())
3822 old_mbase = old_base->as_MergeMem();
3823 else
3824 old_mbase = NULL;
3825 Node* new_base = old_base;
3826
3827 // simplify stacked MergeMems in base memory
3828 if (old_mbase) new_base = old_mbase->base_memory();
3829
3830 // the base memory might contribute new slices beyond my req()
3831 if (old_mbase) grow_to_match(old_mbase);
3832
3833 // Look carefully at the base node if it is a phi.
3834 PhiNode* phi_base;
3835 if (new_base != NULL && new_base->is_Phi())
3836 phi_base = new_base->as_Phi();
3837 else
3838 phi_base = NULL;
3839
3840 Node* phi_reg = NULL;
3841 uint phi_len = (uint)-1;
3842 if (phi_base != NULL && !phi_base->is_copy()) {
3843 // do not examine phi if degraded to a copy
3844 phi_reg = phi_base->region();
3845 phi_len = phi_base->req();
3846 // see if the phi is unfinished
3847 for (uint i = 1; i < phi_len; i++) {
3848 if (phi_base->in(i) == NULL) {
3849 // incomplete phi; do not look at it yet!
3850 phi_reg = NULL;
3851 phi_len = (uint)-1;
3852 break;
3853 }
3854 }
3855 }
3856
3857 // Note: We do not call verify_sparse on entry, because inputs
3858 // can normalize to the base_memory via subsume_node or similar
3859 // mechanisms. This method repairs that damage.
3860
3861 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
3862
3863 // Look at each slice.
3864 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3865 Node* old_in = in(i);
3866 // calculate the old memory value
3867 Node* old_mem = old_in;
3868 if (old_mem == empty_mem) old_mem = old_base;
3869 assert(old_mem == memory_at(i), "");
3870
3871 // maybe update (reslice) the old memory value
3872
3873 // simplify stacked MergeMems
3874 Node* new_mem = old_mem;
3875 MergeMemNode* old_mmem;
3876 if (old_mem != NULL && old_mem->is_MergeMem())
3877 old_mmem = old_mem->as_MergeMem();
3878 else
3879 old_mmem = NULL;
3880 if (old_mmem == this) {
3881 // This can happen if loops break up and safepoints disappear.
3882 // A merge of BotPtr (default) with a RawPtr memory derived from a
3883 // safepoint can be rewritten to a merge of the same BotPtr with
3884 // the BotPtr phi coming into the loop. If that phi disappears
3885 // also, we can end up with a self-loop of the mergemem.
3886 // In general, if loops degenerate and memory effects disappear,
3887 // a mergemem can be left looking at itself. This simply means
3888 // that the mergemem's default should be used, since there is
3889 // no longer any apparent effect on this slice.
3890 // Note: If a memory slice is a MergeMem cycle, it is unreachable
3891 // from start. Update the input to TOP.
3892 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
3893 }
3894 else if (old_mmem != NULL) {
3895 new_mem = old_mmem->memory_at(i);
3896 }
3897 // else preceding memory was not a MergeMem
3898
3899 // replace equivalent phis (unfortunately, they do not GVN together)
3900 if (new_mem != NULL && new_mem != new_base &&
3901 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) {
3902 if (new_mem->is_Phi()) {
3903 PhiNode* phi_mem = new_mem->as_Phi();
3904 for (uint i = 1; i < phi_len; i++) {
3905 if (phi_base->in(i) != phi_mem->in(i)) {
3906 phi_mem = NULL;
3907 break;
3908 }
3909 }
3910 if (phi_mem != NULL) {
3911 // equivalent phi nodes; revert to the def
3912 new_mem = new_base;
3913 }
3914 }
3915 }
3916
3917 // maybe store down a new value
3918 Node* new_in = new_mem;
3919 if (new_in == new_base) new_in = empty_mem;
3920
3921 if (new_in != old_in) {
3922 // Warning: Do not combine this "if" with the previous "if"
3923 // A memory slice might have be be rewritten even if it is semantically
3924 // unchanged, if the base_memory value has changed.
3925 set_req(i, new_in);
3926 progress = this; // Report progress
3927 }
3928 }
3929
3930 if (new_base != old_base) {
3931 set_req(Compile::AliasIdxBot, new_base);
3932 // Don't use set_base_memory(new_base), because we need to update du.
3933 assert(base_memory() == new_base, "");
3934 progress = this;
3935 }
3936
3937 if( base_memory() == this ) {
3938 // a self cycle indicates this memory path is dead
3939 set_req(Compile::AliasIdxBot, empty_mem);
3940 }
3941
3942 // Resolve external cycles by calling Ideal on a MergeMem base_memory
3943 // Recursion must occur after the self cycle check above
3944 if( base_memory()->is_MergeMem() ) {
3945 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
3946 Node *m = phase->transform(new_mbase); // Rollup any cycles
3947 if( m != NULL && (m->is_top() ||
3948 m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem) ) {
3949 // propagate rollup of dead cycle to self
3950 set_req(Compile::AliasIdxBot, empty_mem);
3951 }
3952 }
3953
3954 if( base_memory() == empty_mem ) {
3955 progress = this;
3956 // Cut inputs during Parse phase only.
3957 // During Optimize phase a dead MergeMem node will be subsumed by Top.
3958 if( !can_reshape ) {
3959 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3960 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
3961 }
3962 }
3963 }
3964
3965 if( !progress && base_memory()->is_Phi() && can_reshape ) {
3966 // Check if PhiNode::Ideal's "Split phis through memory merges"
3967 // transform should be attempted. Look for this->phi->this cycle.
3968 uint merge_width = req();
3969 if (merge_width > Compile::AliasIdxRaw) {
3970 PhiNode* phi = base_memory()->as_Phi();
3971 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
3972 if (phi->in(i) == this) {
3973 phase->is_IterGVN()->_worklist.push(phi);
3974 break;
3975 }
3976 }
3977 }
3978 }
3979
3980 assert(progress || verify_sparse(), "please, no dups of base");
3981 return progress;
3982 }
3983
3984 //-------------------------set_base_memory-------------------------------------
3985 void MergeMemNode::set_base_memory(Node *new_base) {
3986 Node* empty_mem = empty_memory();
3987 set_req(Compile::AliasIdxBot, new_base);
3988 assert(memory_at(req()) == new_base, "must set default memory");
3989 // Clear out other occurrences of new_base:
3990 if (new_base != empty_mem) {
3991 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3992 if (in(i) == new_base) set_req(i, empty_mem);
3993 }
3994 }
3995 }
3996
3997 //------------------------------out_RegMask------------------------------------
3998 const RegMask &MergeMemNode::out_RegMask() const {
3999 return RegMask::Empty;
4000 }
4001
4002 //------------------------------dump_spec--------------------------------------
4003 #ifndef PRODUCT
4004 void MergeMemNode::dump_spec(outputStream *st) const {
4005 st->print(" {");
4006 Node* base_mem = base_memory();
4007 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
4008 Node* mem = memory_at(i);
4009 if (mem == base_mem) { st->print(" -"); continue; }
4010 st->print( " N%d:", mem->_idx );
4011 Compile::current()->get_adr_type(i)->dump_on(st);
4012 }
4013 st->print(" }");
4014 }
4015 #endif // !PRODUCT
4016
4017
4018 #ifdef ASSERT
4019 static bool might_be_same(Node* a, Node* b) {
4020 if (a == b) return true;
4021 if (!(a->is_Phi() || b->is_Phi())) return false;
4022 // phis shift around during optimization
4023 return true; // pretty stupid...
4024 }
4025
4026 // verify a narrow slice (either incoming or outgoing)
4027 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
4028 if (!VerifyAliases) return; // don't bother to verify unless requested
4029 if (is_error_reported()) return; // muzzle asserts when debugging an error
4030 if (Node::in_dump()) return; // muzzle asserts when printing
4031 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
4032 assert(n != NULL, "");
4033 // Elide intervening MergeMem's
4034 while (n->is_MergeMem()) {
4035 n = n->as_MergeMem()->memory_at(alias_idx);
4036 }
4037 Compile* C = Compile::current();
4038 const TypePtr* n_adr_type = n->adr_type();
4039 if (n == m->empty_memory()) {
4040 // Implicit copy of base_memory()
4041 } else if (n_adr_type != TypePtr::BOTTOM) {
4042 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type");
4043 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
4044 } else {
4045 // A few places like make_runtime_call "know" that VM calls are narrow,
4046 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
4047 bool expected_wide_mem = false;
4048 if (n == m->base_memory()) {
4049 expected_wide_mem = true;
4050 } else if (alias_idx == Compile::AliasIdxRaw ||
4051 n == m->memory_at(Compile::AliasIdxRaw)) {
4052 expected_wide_mem = true;
4053 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
4054 // memory can "leak through" calls on channels that
4055 // are write-once. Allow this also.
4056 expected_wide_mem = true;
4057 }
4058 assert(expected_wide_mem, "expected narrow slice replacement");
4059 }
4060 }
4061 #else // !ASSERT
4062 #define verify_memory_slice(m,i,n) (0) // PRODUCT version is no-op
4063 #endif
4064
4065
4066 //-----------------------------memory_at---------------------------------------
4067 Node* MergeMemNode::memory_at(uint alias_idx) const {
4068 assert(alias_idx >= Compile::AliasIdxRaw ||
4069 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0,
4070 "must avoid base_memory and AliasIdxTop");
4071
4072 // Otherwise, it is a narrow slice.
4073 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
4074 Compile *C = Compile::current();
4075 if (is_empty_memory(n)) {
4076 // the array is sparse; empty slots are the "top" node
4077 n = base_memory();
4078 assert(Node::in_dump()
4079 || n == NULL || n->bottom_type() == Type::TOP
4080 || n->adr_type() == NULL // address is TOP
4081 || n->adr_type() == TypePtr::BOTTOM
4082 || n->adr_type() == TypeRawPtr::BOTTOM
4083 || Compile::current()->AliasLevel() == 0,
4084 "must be a wide memory");
4085 // AliasLevel == 0 if we are organizing the memory states manually.
4086 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
4087 } else {
4088 // make sure the stored slice is sane
4089 #ifdef ASSERT
4090 if (is_error_reported() || Node::in_dump()) {
4091 } else if (might_be_same(n, base_memory())) {
4092 // Give it a pass: It is a mostly harmless repetition of the base.
4093 // This can arise normally from node subsumption during optimization.
4094 } else {
4095 verify_memory_slice(this, alias_idx, n);
4096 }
4097 #endif
4098 }
4099 return n;
4100 }
4101
4102 //---------------------------set_memory_at-------------------------------------
4103 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
4104 verify_memory_slice(this, alias_idx, n);
4105 Node* empty_mem = empty_memory();
4106 if (n == base_memory()) n = empty_mem; // collapse default
4107 uint need_req = alias_idx+1;
4108 if (req() < need_req) {
4109 if (n == empty_mem) return; // already the default, so do not grow me
4110 // grow the sparse array
4111 do {
4112 add_req(empty_mem);
4113 } while (req() < need_req);
4114 }
4115 set_req( alias_idx, n );
4116 }
4117
4118
4119
4120 //--------------------------iteration_setup------------------------------------
4121 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
4122 if (other != NULL) {
4123 grow_to_match(other);
4124 // invariant: the finite support of mm2 is within mm->req()
4125 #ifdef ASSERT
4126 for (uint i = req(); i < other->req(); i++) {
4127 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
4128 }
4129 #endif
4130 }
4131 // Replace spurious copies of base_memory by top.
4132 Node* base_mem = base_memory();
4133 if (base_mem != NULL && !base_mem->is_top()) {
4134 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
4135 if (in(i) == base_mem)
4136 set_req(i, empty_memory());
4137 }
4138 }
4139 }
4140
4141 //---------------------------grow_to_match-------------------------------------
4142 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
4143 Node* empty_mem = empty_memory();
4144 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
4145 // look for the finite support of the other memory
4146 for (uint i = other->req(); --i >= req(); ) {
4147 if (other->in(i) != empty_mem) {
4148 uint new_len = i+1;
4149 while (req() < new_len) add_req(empty_mem);
4150 break;
4151 }
4152 }
4153 }
4154
4155 //---------------------------verify_sparse-------------------------------------
4156 #ifndef PRODUCT
4157 bool MergeMemNode::verify_sparse() const {
4158 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
4159 Node* base_mem = base_memory();
4160 // The following can happen in degenerate cases, since empty==top.
4161 if (is_empty_memory(base_mem)) return true;
4162 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4163 assert(in(i) != NULL, "sane slice");
4164 if (in(i) == base_mem) return false; // should have been the sentinel value!
4165 }
4166 return true;
4167 }
4168
4169 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
4170 Node* n;
4171 n = mm->in(idx);
4172 if (mem == n) return true; // might be empty_memory()
4173 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
4174 if (mem == n) return true;
4175 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) {
4176 if (mem == n) return true;
4177 if (n == NULL) break;
4178 }
4179 return false;
4180 }
4181 #endif // !PRODUCT