1 /*
2 * Copyright (c) 1997, 2011, 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 (klass == phase->C->env()->String_klass() &&
1563 adr->is_AddP() && off != Type::OffsetBot) {
1564 // For constant Strings treat the final 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 ciField* field = phase->C->env()->String_klass()->get_field_by_offset(off, false);
1569 if (field != NULL && field->is_final()) {
1570 ciObject* string = t->const_oop();
1571 ciConstant constant = string->as_instance()->field_value(field);
1572 if (constant.basic_type() == T_INT) {
1573 return TypeInt::make(constant.as_int());
1574 } else if (constant.basic_type() == T_ARRAY) {
1575 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
1576 return TypeNarrowOop::make_from_constant(constant.as_object(), true);
1577 } else {
1578 return TypeOopPtr::make_from_constant(constant.as_object(), true);
1579 }
1580 }
1581 }
1582 }
1583 }
1584 } else if (tp->base() == Type::KlassPtr) {
1585 assert( off != Type::OffsetBot ||
1586 // arrays can be cast to Objects
1587 tp->is_klassptr()->klass()->is_java_lang_Object() ||
1588 // also allow array-loading from the primary supertype
1589 // array during subtype checks
1590 Opcode() == Op_LoadKlass,
1591 "Field accesses must be precise" );
1592 // For klass/static loads, we expect the _type to be precise
1593 }
1594
1595 const TypeKlassPtr *tkls = tp->isa_klassptr();
1596 if (tkls != NULL && !StressReflectiveCode) {
1597 ciKlass* klass = tkls->klass();
1598 if (klass->is_loaded() && tkls->klass_is_exact()) {
1599 // We are loading a field from a Klass metaobject whose identity
1600 // is known at compile time (the type is "exact" or "precise").
1601 // Check for fields we know are maintained as constants by the VM.
1602 if (tkls->offset() == Klass::super_check_offset_offset_in_bytes() + (int)sizeof(oopDesc)) {
1603 // The field is Klass::_super_check_offset. Return its (constant) value.
1604 // (Folds up type checking code.)
1605 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
1606 return TypeInt::make(klass->super_check_offset());
1607 }
1608 // Compute index into primary_supers array
1609 juint depth = (tkls->offset() - (Klass::primary_supers_offset_in_bytes() + (int)sizeof(oopDesc))) / sizeof(klassOop);
1610 // Check for overflowing; use unsigned compare to handle the negative case.
1611 if( depth < ciKlass::primary_super_limit() ) {
1612 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1613 // (Folds up type checking code.)
1614 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1615 ciKlass *ss = klass->super_of_depth(depth);
1616 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1617 }
1618 const Type* aift = load_array_final_field(tkls, klass);
1619 if (aift != NULL) return aift;
1620 if (tkls->offset() == in_bytes(arrayKlass::component_mirror_offset()) + (int)sizeof(oopDesc)
1621 && klass->is_array_klass()) {
1622 // The field is arrayKlass::_component_mirror. Return its (constant) value.
1623 // (Folds up aClassConstant.getComponentType, common in Arrays.copyOf.)
1624 assert(Opcode() == Op_LoadP, "must load an oop from _component_mirror");
1625 return TypeInstPtr::make(klass->as_array_klass()->component_mirror());
1626 }
1627 if (tkls->offset() == Klass::java_mirror_offset_in_bytes() + (int)sizeof(oopDesc)) {
1628 // The field is Klass::_java_mirror. Return its (constant) value.
1629 // (Folds up the 2nd indirection in anObjConstant.getClass().)
1630 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
1631 return TypeInstPtr::make(klass->java_mirror());
1632 }
1633 }
1634
1635 // We can still check if we are loading from the primary_supers array at a
1636 // shallow enough depth. Even though the klass is not exact, entries less
1637 // than or equal to its super depth are correct.
1638 if (klass->is_loaded() ) {
1639 ciType *inner = klass->klass();
1640 while( inner->is_obj_array_klass() )
1641 inner = inner->as_obj_array_klass()->base_element_type();
1642 if( inner->is_instance_klass() &&
1643 !inner->as_instance_klass()->flags().is_interface() ) {
1644 // Compute index into primary_supers array
1645 juint depth = (tkls->offset() - (Klass::primary_supers_offset_in_bytes() + (int)sizeof(oopDesc))) / sizeof(klassOop);
1646 // Check for overflowing; use unsigned compare to handle the negative case.
1647 if( depth < ciKlass::primary_super_limit() &&
1648 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case
1649 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1650 // (Folds up type checking code.)
1651 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1652 ciKlass *ss = klass->super_of_depth(depth);
1653 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1654 }
1655 }
1656 }
1657
1658 // If the type is enough to determine that the thing is not an array,
1659 // we can give the layout_helper a positive interval type.
1660 // This will help short-circuit some reflective code.
1661 if (tkls->offset() == Klass::layout_helper_offset_in_bytes() + (int)sizeof(oopDesc)
1662 && !klass->is_array_klass() // not directly typed as an array
1663 && !klass->is_interface() // specifically not Serializable & Cloneable
1664 && !klass->is_java_lang_Object() // not the supertype of all T[]
1665 ) {
1666 // Note: When interfaces are reliable, we can narrow the interface
1667 // test to (klass != Serializable && klass != Cloneable).
1668 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
1669 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
1670 // The key property of this type is that it folds up tests
1671 // for array-ness, since it proves that the layout_helper is positive.
1672 // Thus, a generic value like the basic object layout helper works fine.
1673 return TypeInt::make(min_size, max_jint, Type::WidenMin);
1674 }
1675 }
1676
1677 // If we are loading from a freshly-allocated object, produce a zero,
1678 // if the load is provably beyond the header of the object.
1679 // (Also allow a variable load from a fresh array to produce zero.)
1680 if (ReduceFieldZeroing) {
1681 Node* value = can_see_stored_value(mem,phase);
1682 if (value != NULL && value->is_Con())
1683 return value->bottom_type();
1684 }
1685
1686 const TypeOopPtr *tinst = tp->isa_oopptr();
1687 if (tinst != NULL && tinst->is_known_instance_field()) {
1688 // If we have an instance type and our memory input is the
1689 // programs's initial memory state, there is no matching store,
1690 // so just return a zero of the appropriate type
1691 Node *mem = in(MemNode::Memory);
1692 if (mem->is_Parm() && mem->in(0)->is_Start()) {
1693 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
1694 return Type::get_zero_type(_type->basic_type());
1695 }
1696 }
1697 return _type;
1698 }
1699
1700 //------------------------------match_edge-------------------------------------
1701 // Do we Match on this edge index or not? Match only the address.
1702 uint LoadNode::match_edge(uint idx) const {
1703 return idx == MemNode::Address;
1704 }
1705
1706 //--------------------------LoadBNode::Ideal--------------------------------------
1707 //
1708 // If the previous store is to the same address as this load,
1709 // and the value stored was larger than a byte, replace this load
1710 // with the value stored truncated to a byte. If no truncation is
1711 // needed, the replacement is done in LoadNode::Identity().
1712 //
1713 Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1714 Node* mem = in(MemNode::Memory);
1715 Node* value = can_see_stored_value(mem,phase);
1716 if( value && !phase->type(value)->higher_equal( _type ) ) {
1717 Node *result = phase->transform( new (phase->C, 3) LShiftINode(value, phase->intcon(24)) );
1718 return new (phase->C, 3) RShiftINode(result, phase->intcon(24));
1719 }
1720 // Identity call will handle the case where truncation is not needed.
1721 return LoadNode::Ideal(phase, can_reshape);
1722 }
1723
1724 //--------------------------LoadUBNode::Ideal-------------------------------------
1725 //
1726 // If the previous store is to the same address as this load,
1727 // and the value stored was larger than a byte, replace this load
1728 // with the value stored truncated to a byte. If no truncation is
1729 // needed, the replacement is done in LoadNode::Identity().
1730 //
1731 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
1732 Node* mem = in(MemNode::Memory);
1733 Node* value = can_see_stored_value(mem, phase);
1734 if (value && !phase->type(value)->higher_equal(_type))
1735 return new (phase->C, 3) AndINode(value, phase->intcon(0xFF));
1736 // Identity call will handle the case where truncation is not needed.
1737 return LoadNode::Ideal(phase, can_reshape);
1738 }
1739
1740 //--------------------------LoadUSNode::Ideal-------------------------------------
1741 //
1742 // If the previous store is to the same address as this load,
1743 // and the value stored was larger than a char, replace this load
1744 // with the value stored truncated to a char. If no truncation is
1745 // needed, the replacement is done in LoadNode::Identity().
1746 //
1747 Node *LoadUSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1748 Node* mem = in(MemNode::Memory);
1749 Node* value = can_see_stored_value(mem,phase);
1750 if( value && !phase->type(value)->higher_equal( _type ) )
1751 return new (phase->C, 3) AndINode(value,phase->intcon(0xFFFF));
1752 // Identity call will handle the case where truncation is not needed.
1753 return LoadNode::Ideal(phase, can_reshape);
1754 }
1755
1756 //--------------------------LoadSNode::Ideal--------------------------------------
1757 //
1758 // If the previous store is to the same address as this load,
1759 // and the value stored was larger than a short, replace this load
1760 // with the value stored truncated to a short. If no truncation is
1761 // needed, the replacement is done in LoadNode::Identity().
1762 //
1763 Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1764 Node* mem = in(MemNode::Memory);
1765 Node* value = can_see_stored_value(mem,phase);
1766 if( value && !phase->type(value)->higher_equal( _type ) ) {
1767 Node *result = phase->transform( new (phase->C, 3) LShiftINode(value, phase->intcon(16)) );
1768 return new (phase->C, 3) RShiftINode(result, phase->intcon(16));
1769 }
1770 // Identity call will handle the case where truncation is not needed.
1771 return LoadNode::Ideal(phase, can_reshape);
1772 }
1773
1774 //=============================================================================
1775 //----------------------------LoadKlassNode::make------------------------------
1776 // Polymorphic factory method:
1777 Node *LoadKlassNode::make( PhaseGVN& gvn, Node *mem, Node *adr, const TypePtr* at, const TypeKlassPtr *tk ) {
1778 Compile* C = gvn.C;
1779 Node *ctl = NULL;
1780 // sanity check the alias category against the created node type
1781 const TypeOopPtr *adr_type = adr->bottom_type()->isa_oopptr();
1782 assert(adr_type != NULL, "expecting TypeOopPtr");
1783 #ifdef _LP64
1784 if (adr_type->is_ptr_to_narrowoop()) {
1785 Node* load_klass = gvn.transform(new (C, 3) LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowoop()));
1786 return new (C, 2) DecodeNNode(load_klass, load_klass->bottom_type()->make_ptr());
1787 }
1788 #endif
1789 assert(!adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
1790 return new (C, 3) LoadKlassNode(ctl, mem, adr, at, tk);
1791 }
1792
1793 //------------------------------Value------------------------------------------
1794 const Type *LoadKlassNode::Value( PhaseTransform *phase ) const {
1795 return klass_value_common(phase);
1796 }
1797
1798 const Type *LoadNode::klass_value_common( PhaseTransform *phase ) const {
1799 // Either input is TOP ==> the result is TOP
1800 const Type *t1 = phase->type( in(MemNode::Memory) );
1801 if (t1 == Type::TOP) return Type::TOP;
1802 Node *adr = in(MemNode::Address);
1803 const Type *t2 = phase->type( adr );
1804 if (t2 == Type::TOP) return Type::TOP;
1805 const TypePtr *tp = t2->is_ptr();
1806 if (TypePtr::above_centerline(tp->ptr()) ||
1807 tp->ptr() == TypePtr::Null) return Type::TOP;
1808
1809 // Return a more precise klass, if possible
1810 const TypeInstPtr *tinst = tp->isa_instptr();
1811 if (tinst != NULL) {
1812 ciInstanceKlass* ik = tinst->klass()->as_instance_klass();
1813 int offset = tinst->offset();
1814 if (ik == phase->C->env()->Class_klass()
1815 && (offset == java_lang_Class::klass_offset_in_bytes() ||
1816 offset == java_lang_Class::array_klass_offset_in_bytes())) {
1817 // We are loading a special hidden field from a Class mirror object,
1818 // the field which points to the VM's Klass metaobject.
1819 ciType* t = tinst->java_mirror_type();
1820 // java_mirror_type returns non-null for compile-time Class constants.
1821 if (t != NULL) {
1822 // constant oop => constant klass
1823 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
1824 return TypeKlassPtr::make(ciArrayKlass::make(t));
1825 }
1826 if (!t->is_klass()) {
1827 // a primitive Class (e.g., int.class) has NULL for a klass field
1828 return TypePtr::NULL_PTR;
1829 }
1830 // (Folds up the 1st indirection in aClassConstant.getModifiers().)
1831 return TypeKlassPtr::make(t->as_klass());
1832 }
1833 // non-constant mirror, so we can't tell what's going on
1834 }
1835 if( !ik->is_loaded() )
1836 return _type; // Bail out if not loaded
1837 if (offset == oopDesc::klass_offset_in_bytes()) {
1838 if (tinst->klass_is_exact()) {
1839 return TypeKlassPtr::make(ik);
1840 }
1841 // See if we can become precise: no subklasses and no interface
1842 // (Note: We need to support verified interfaces.)
1843 if (!ik->is_interface() && !ik->has_subklass()) {
1844 //assert(!UseExactTypes, "this code should be useless with exact types");
1845 // Add a dependence; if any subclass added we need to recompile
1846 if (!ik->is_final()) {
1847 // %%% should use stronger assert_unique_concrete_subtype instead
1848 phase->C->dependencies()->assert_leaf_type(ik);
1849 }
1850 // Return precise klass
1851 return TypeKlassPtr::make(ik);
1852 }
1853
1854 // Return root of possible klass
1855 return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/);
1856 }
1857 }
1858
1859 // Check for loading klass from an array
1860 const TypeAryPtr *tary = tp->isa_aryptr();
1861 if( tary != NULL ) {
1862 ciKlass *tary_klass = tary->klass();
1863 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP
1864 && tary->offset() == oopDesc::klass_offset_in_bytes()) {
1865 if (tary->klass_is_exact()) {
1866 return TypeKlassPtr::make(tary_klass);
1867 }
1868 ciArrayKlass *ak = tary->klass()->as_array_klass();
1869 // If the klass is an object array, we defer the question to the
1870 // array component klass.
1871 if( ak->is_obj_array_klass() ) {
1872 assert( ak->is_loaded(), "" );
1873 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass();
1874 if( base_k->is_loaded() && base_k->is_instance_klass() ) {
1875 ciInstanceKlass* ik = base_k->as_instance_klass();
1876 // See if we can become precise: no subklasses and no interface
1877 if (!ik->is_interface() && !ik->has_subklass()) {
1878 //assert(!UseExactTypes, "this code should be useless with exact types");
1879 // Add a dependence; if any subclass added we need to recompile
1880 if (!ik->is_final()) {
1881 phase->C->dependencies()->assert_leaf_type(ik);
1882 }
1883 // Return precise array klass
1884 return TypeKlassPtr::make(ak);
1885 }
1886 }
1887 return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/);
1888 } else { // Found a type-array?
1889 //assert(!UseExactTypes, "this code should be useless with exact types");
1890 assert( ak->is_type_array_klass(), "" );
1891 return TypeKlassPtr::make(ak); // These are always precise
1892 }
1893 }
1894 }
1895
1896 // Check for loading klass from an array klass
1897 const TypeKlassPtr *tkls = tp->isa_klassptr();
1898 if (tkls != NULL && !StressReflectiveCode) {
1899 ciKlass* klass = tkls->klass();
1900 if( !klass->is_loaded() )
1901 return _type; // Bail out if not loaded
1902 if( klass->is_obj_array_klass() &&
1903 (uint)tkls->offset() == objArrayKlass::element_klass_offset_in_bytes() + sizeof(oopDesc)) {
1904 ciKlass* elem = klass->as_obj_array_klass()->element_klass();
1905 // // Always returning precise element type is incorrect,
1906 // // e.g., element type could be object and array may contain strings
1907 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
1908
1909 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
1910 // according to the element type's subclassing.
1911 return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/);
1912 }
1913 if( klass->is_instance_klass() && tkls->klass_is_exact() &&
1914 (uint)tkls->offset() == Klass::super_offset_in_bytes() + sizeof(oopDesc)) {
1915 ciKlass* sup = klass->as_instance_klass()->super();
1916 // The field is Klass::_super. Return its (constant) value.
1917 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
1918 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR;
1919 }
1920 }
1921
1922 // Bailout case
1923 return LoadNode::Value(phase);
1924 }
1925
1926 //------------------------------Identity---------------------------------------
1927 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
1928 // Also feed through the klass in Allocate(...klass...)._klass.
1929 Node* LoadKlassNode::Identity( PhaseTransform *phase ) {
1930 return klass_identity_common(phase);
1931 }
1932
1933 Node* LoadNode::klass_identity_common(PhaseTransform *phase ) {
1934 Node* x = LoadNode::Identity(phase);
1935 if (x != this) return x;
1936
1937 // Take apart the address into an oop and and offset.
1938 // Return 'this' if we cannot.
1939 Node* adr = in(MemNode::Address);
1940 intptr_t offset = 0;
1941 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
1942 if (base == NULL) return this;
1943 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
1944 if (toop == NULL) return this;
1945
1946 // We can fetch the klass directly through an AllocateNode.
1947 // This works even if the klass is not constant (clone or newArray).
1948 if (offset == oopDesc::klass_offset_in_bytes()) {
1949 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
1950 if (allocated_klass != NULL) {
1951 return allocated_klass;
1952 }
1953 }
1954
1955 // Simplify k.java_mirror.as_klass to plain k, where k is a klassOop.
1956 // Simplify ak.component_mirror.array_klass to plain ak, ak an arrayKlass.
1957 // See inline_native_Class_query for occurrences of these patterns.
1958 // Java Example: x.getClass().isAssignableFrom(y)
1959 // Java Example: Array.newInstance(x.getClass().getComponentType(), n)
1960 //
1961 // This improves reflective code, often making the Class
1962 // mirror go completely dead. (Current exception: Class
1963 // mirrors may appear in debug info, but we could clean them out by
1964 // introducing a new debug info operator for klassOop.java_mirror).
1965 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass()
1966 && (offset == java_lang_Class::klass_offset_in_bytes() ||
1967 offset == java_lang_Class::array_klass_offset_in_bytes())) {
1968 // We are loading a special hidden field from a Class mirror,
1969 // the field which points to its Klass or arrayKlass metaobject.
1970 if (base->is_Load()) {
1971 Node* adr2 = base->in(MemNode::Address);
1972 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
1973 if (tkls != NULL && !tkls->empty()
1974 && (tkls->klass()->is_instance_klass() ||
1975 tkls->klass()->is_array_klass())
1976 && adr2->is_AddP()
1977 ) {
1978 int mirror_field = Klass::java_mirror_offset_in_bytes();
1979 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
1980 mirror_field = in_bytes(arrayKlass::component_mirror_offset());
1981 }
1982 if (tkls->offset() == mirror_field + (int)sizeof(oopDesc)) {
1983 return adr2->in(AddPNode::Base);
1984 }
1985 }
1986 }
1987 }
1988
1989 return this;
1990 }
1991
1992
1993 //------------------------------Value------------------------------------------
1994 const Type *LoadNKlassNode::Value( PhaseTransform *phase ) const {
1995 const Type *t = klass_value_common(phase);
1996 if (t == Type::TOP)
1997 return t;
1998
1999 return t->make_narrowoop();
2000 }
2001
2002 //------------------------------Identity---------------------------------------
2003 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
2004 // Also feed through the klass in Allocate(...klass...)._klass.
2005 Node* LoadNKlassNode::Identity( PhaseTransform *phase ) {
2006 Node *x = klass_identity_common(phase);
2007
2008 const Type *t = phase->type( x );
2009 if( t == Type::TOP ) return x;
2010 if( t->isa_narrowoop()) return x;
2011
2012 return phase->transform(new (phase->C, 2) EncodePNode(x, t->make_narrowoop()));
2013 }
2014
2015 //------------------------------Value-----------------------------------------
2016 const Type *LoadRangeNode::Value( PhaseTransform *phase ) const {
2017 // Either input is TOP ==> the result is TOP
2018 const Type *t1 = phase->type( in(MemNode::Memory) );
2019 if( t1 == Type::TOP ) return Type::TOP;
2020 Node *adr = in(MemNode::Address);
2021 const Type *t2 = phase->type( adr );
2022 if( t2 == Type::TOP ) return Type::TOP;
2023 const TypePtr *tp = t2->is_ptr();
2024 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
2025 const TypeAryPtr *tap = tp->isa_aryptr();
2026 if( !tap ) return _type;
2027 return tap->size();
2028 }
2029
2030 //-------------------------------Ideal---------------------------------------
2031 // Feed through the length in AllocateArray(...length...)._length.
2032 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2033 Node* p = MemNode::Ideal_common(phase, can_reshape);
2034 if (p) return (p == NodeSentinel) ? NULL : p;
2035
2036 // Take apart the address into an oop and and offset.
2037 // Return 'this' if we cannot.
2038 Node* adr = in(MemNode::Address);
2039 intptr_t offset = 0;
2040 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2041 if (base == NULL) return NULL;
2042 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2043 if (tary == NULL) return NULL;
2044
2045 // We can fetch the length directly through an AllocateArrayNode.
2046 // This works even if the length is not constant (clone or newArray).
2047 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2048 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2049 if (alloc != NULL) {
2050 Node* allocated_length = alloc->Ideal_length();
2051 Node* len = alloc->make_ideal_length(tary, phase);
2052 if (allocated_length != len) {
2053 // New CastII improves on this.
2054 return len;
2055 }
2056 }
2057 }
2058
2059 return NULL;
2060 }
2061
2062 //------------------------------Identity---------------------------------------
2063 // Feed through the length in AllocateArray(...length...)._length.
2064 Node* LoadRangeNode::Identity( PhaseTransform *phase ) {
2065 Node* x = LoadINode::Identity(phase);
2066 if (x != this) return x;
2067
2068 // Take apart the address into an oop and and offset.
2069 // Return 'this' if we cannot.
2070 Node* adr = in(MemNode::Address);
2071 intptr_t offset = 0;
2072 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2073 if (base == NULL) return this;
2074 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2075 if (tary == NULL) return this;
2076
2077 // We can fetch the length directly through an AllocateArrayNode.
2078 // This works even if the length is not constant (clone or newArray).
2079 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2080 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2081 if (alloc != NULL) {
2082 Node* allocated_length = alloc->Ideal_length();
2083 // Do not allow make_ideal_length to allocate a CastII node.
2084 Node* len = alloc->make_ideal_length(tary, phase, false);
2085 if (allocated_length == len) {
2086 // Return allocated_length only if it would not be improved by a CastII.
2087 return allocated_length;
2088 }
2089 }
2090 }
2091
2092 return this;
2093
2094 }
2095
2096 //=============================================================================
2097 //---------------------------StoreNode::make-----------------------------------
2098 // Polymorphic factory method:
2099 StoreNode* StoreNode::make( PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt ) {
2100 Compile* C = gvn.C;
2101 assert( C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2102 ctl != NULL, "raw memory operations should have control edge");
2103
2104 switch (bt) {
2105 case T_BOOLEAN:
2106 case T_BYTE: return new (C, 4) StoreBNode(ctl, mem, adr, adr_type, val);
2107 case T_INT: return new (C, 4) StoreINode(ctl, mem, adr, adr_type, val);
2108 case T_CHAR:
2109 case T_SHORT: return new (C, 4) StoreCNode(ctl, mem, adr, adr_type, val);
2110 case T_LONG: return new (C, 4) StoreLNode(ctl, mem, adr, adr_type, val);
2111 case T_FLOAT: return new (C, 4) StoreFNode(ctl, mem, adr, adr_type, val);
2112 case T_DOUBLE: return new (C, 4) StoreDNode(ctl, mem, adr, adr_type, val);
2113 case T_ADDRESS:
2114 case T_OBJECT:
2115 #ifdef _LP64
2116 if (adr->bottom_type()->is_ptr_to_narrowoop() ||
2117 (UseCompressedOops && val->bottom_type()->isa_klassptr() &&
2118 adr->bottom_type()->isa_rawptr())) {
2119 val = gvn.transform(new (C, 2) EncodePNode(val, val->bottom_type()->make_narrowoop()));
2120 return new (C, 4) StoreNNode(ctl, mem, adr, adr_type, val);
2121 } else
2122 #endif
2123 {
2124 return new (C, 4) StorePNode(ctl, mem, adr, adr_type, val);
2125 }
2126 }
2127 ShouldNotReachHere();
2128 return (StoreNode*)NULL;
2129 }
2130
2131 StoreLNode* StoreLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val) {
2132 bool require_atomic = true;
2133 return new (C, 4) StoreLNode(ctl, mem, adr, adr_type, val, require_atomic);
2134 }
2135
2136
2137 //--------------------------bottom_type----------------------------------------
2138 const Type *StoreNode::bottom_type() const {
2139 return Type::MEMORY;
2140 }
2141
2142 //------------------------------hash-------------------------------------------
2143 uint StoreNode::hash() const {
2144 // unroll addition of interesting fields
2145 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2146
2147 // Since they are not commoned, do not hash them:
2148 return NO_HASH;
2149 }
2150
2151 //------------------------------Ideal------------------------------------------
2152 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
2153 // When a store immediately follows a relevant allocation/initialization,
2154 // try to capture it into the initialization, or hoist it above.
2155 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2156 Node* p = MemNode::Ideal_common(phase, can_reshape);
2157 if (p) return (p == NodeSentinel) ? NULL : p;
2158
2159 Node* mem = in(MemNode::Memory);
2160 Node* address = in(MemNode::Address);
2161
2162 // Back-to-back stores to same address? Fold em up.
2163 // Generally unsafe if I have intervening uses...
2164 if (mem->is_Store() && phase->eqv_uncast(mem->in(MemNode::Address), address)) {
2165 // Looking at a dead closed cycle of memory?
2166 assert(mem != mem->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
2167
2168 assert(Opcode() == mem->Opcode() ||
2169 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw,
2170 "no mismatched stores, except on raw memory");
2171
2172 if (mem->outcnt() == 1 && // check for intervening uses
2173 mem->as_Store()->memory_size() <= this->memory_size()) {
2174 // If anybody other than 'this' uses 'mem', we cannot fold 'mem' away.
2175 // For example, 'mem' might be the final state at a conditional return.
2176 // Or, 'mem' might be used by some node which is live at the same time
2177 // 'this' is live, which might be unschedulable. So, require exactly
2178 // ONE user, the 'this' store, until such time as we clone 'mem' for
2179 // each of 'mem's uses (thus making the exactly-1-user-rule hold true).
2180 if (can_reshape) { // (%%% is this an anachronism?)
2181 set_req_X(MemNode::Memory, mem->in(MemNode::Memory),
2182 phase->is_IterGVN());
2183 } else {
2184 // It's OK to do this in the parser, since DU info is always accurate,
2185 // and the parser always refers to nodes via SafePointNode maps.
2186 set_req(MemNode::Memory, mem->in(MemNode::Memory));
2187 }
2188 return this;
2189 }
2190 }
2191
2192 // Capture an unaliased, unconditional, simple store into an initializer.
2193 // Or, if it is independent of the allocation, hoist it above the allocation.
2194 if (ReduceFieldZeroing && /*can_reshape &&*/
2195 mem->is_Proj() && mem->in(0)->is_Initialize()) {
2196 InitializeNode* init = mem->in(0)->as_Initialize();
2197 intptr_t offset = init->can_capture_store(this, phase);
2198 if (offset > 0) {
2199 Node* moved = init->capture_store(this, offset, phase);
2200 // If the InitializeNode captured me, it made a raw copy of me,
2201 // and I need to disappear.
2202 if (moved != NULL) {
2203 // %%% hack to ensure that Ideal returns a new node:
2204 mem = MergeMemNode::make(phase->C, mem);
2205 return mem; // fold me away
2206 }
2207 }
2208 }
2209
2210 return NULL; // No further progress
2211 }
2212
2213 //------------------------------Value-----------------------------------------
2214 const Type *StoreNode::Value( PhaseTransform *phase ) const {
2215 // Either input is TOP ==> the result is TOP
2216 const Type *t1 = phase->type( in(MemNode::Memory) );
2217 if( t1 == Type::TOP ) return Type::TOP;
2218 const Type *t2 = phase->type( in(MemNode::Address) );
2219 if( t2 == Type::TOP ) return Type::TOP;
2220 const Type *t3 = phase->type( in(MemNode::ValueIn) );
2221 if( t3 == Type::TOP ) return Type::TOP;
2222 return Type::MEMORY;
2223 }
2224
2225 //------------------------------Identity---------------------------------------
2226 // Remove redundant stores:
2227 // Store(m, p, Load(m, p)) changes to m.
2228 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
2229 Node *StoreNode::Identity( PhaseTransform *phase ) {
2230 Node* mem = in(MemNode::Memory);
2231 Node* adr = in(MemNode::Address);
2232 Node* val = in(MemNode::ValueIn);
2233
2234 // Load then Store? Then the Store is useless
2235 if (val->is_Load() &&
2236 phase->eqv_uncast( val->in(MemNode::Address), adr ) &&
2237 phase->eqv_uncast( val->in(MemNode::Memory ), mem ) &&
2238 val->as_Load()->store_Opcode() == Opcode()) {
2239 return mem;
2240 }
2241
2242 // Two stores in a row of the same value?
2243 if (mem->is_Store() &&
2244 phase->eqv_uncast( mem->in(MemNode::Address), adr ) &&
2245 phase->eqv_uncast( mem->in(MemNode::ValueIn), val ) &&
2246 mem->Opcode() == Opcode()) {
2247 return mem;
2248 }
2249
2250 // Store of zero anywhere into a freshly-allocated object?
2251 // Then the store is useless.
2252 // (It must already have been captured by the InitializeNode.)
2253 if (ReduceFieldZeroing && phase->type(val)->is_zero_type()) {
2254 // a newly allocated object is already all-zeroes everywhere
2255 if (mem->is_Proj() && mem->in(0)->is_Allocate()) {
2256 return mem;
2257 }
2258
2259 // the store may also apply to zero-bits in an earlier object
2260 Node* prev_mem = find_previous_store(phase);
2261 // Steps (a), (b): Walk past independent stores to find an exact match.
2262 if (prev_mem != NULL) {
2263 Node* prev_val = can_see_stored_value(prev_mem, phase);
2264 if (prev_val != NULL && phase->eqv(prev_val, val)) {
2265 // prev_val and val might differ by a cast; it would be good
2266 // to keep the more informative of the two.
2267 return mem;
2268 }
2269 }
2270 }
2271
2272 return this;
2273 }
2274
2275 //------------------------------match_edge-------------------------------------
2276 // Do we Match on this edge index or not? Match only memory & value
2277 uint StoreNode::match_edge(uint idx) const {
2278 return idx == MemNode::Address || idx == MemNode::ValueIn;
2279 }
2280
2281 //------------------------------cmp--------------------------------------------
2282 // Do not common stores up together. They generally have to be split
2283 // back up anyways, so do not bother.
2284 uint StoreNode::cmp( const Node &n ) const {
2285 return (&n == this); // Always fail except on self
2286 }
2287
2288 //------------------------------Ideal_masked_input-----------------------------
2289 // Check for a useless mask before a partial-word store
2290 // (StoreB ... (AndI valIn conIa) )
2291 // If (conIa & mask == mask) this simplifies to
2292 // (StoreB ... (valIn) )
2293 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
2294 Node *val = in(MemNode::ValueIn);
2295 if( val->Opcode() == Op_AndI ) {
2296 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2297 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
2298 set_req(MemNode::ValueIn, val->in(1));
2299 return this;
2300 }
2301 }
2302 return NULL;
2303 }
2304
2305
2306 //------------------------------Ideal_sign_extended_input----------------------
2307 // Check for useless sign-extension before a partial-word store
2308 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) )
2309 // If (conIL == conIR && conIR <= num_bits) this simplifies to
2310 // (StoreB ... (valIn) )
2311 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) {
2312 Node *val = in(MemNode::ValueIn);
2313 if( val->Opcode() == Op_RShiftI ) {
2314 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2315 if( t && t->is_con() && (t->get_con() <= num_bits) ) {
2316 Node *shl = val->in(1);
2317 if( shl->Opcode() == Op_LShiftI ) {
2318 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int();
2319 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) {
2320 set_req(MemNode::ValueIn, shl->in(1));
2321 return this;
2322 }
2323 }
2324 }
2325 }
2326 return NULL;
2327 }
2328
2329 //------------------------------value_never_loaded-----------------------------------
2330 // Determine whether there are any possible loads of the value stored.
2331 // For simplicity, we actually check if there are any loads from the
2332 // address stored to, not just for loads of the value stored by this node.
2333 //
2334 bool StoreNode::value_never_loaded( PhaseTransform *phase) const {
2335 Node *adr = in(Address);
2336 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
2337 if (adr_oop == NULL)
2338 return false;
2339 if (!adr_oop->is_known_instance_field())
2340 return false; // if not a distinct instance, there may be aliases of the address
2341 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
2342 Node *use = adr->fast_out(i);
2343 int opc = use->Opcode();
2344 if (use->is_Load() || use->is_LoadStore()) {
2345 return false;
2346 }
2347 }
2348 return true;
2349 }
2350
2351 //=============================================================================
2352 //------------------------------Ideal------------------------------------------
2353 // If the store is from an AND mask that leaves the low bits untouched, then
2354 // we can skip the AND operation. If the store is from a sign-extension
2355 // (a left shift, then right shift) we can skip both.
2356 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
2357 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
2358 if( progress != NULL ) return progress;
2359
2360 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
2361 if( progress != NULL ) return progress;
2362
2363 // Finally check the default case
2364 return StoreNode::Ideal(phase, can_reshape);
2365 }
2366
2367 //=============================================================================
2368 //------------------------------Ideal------------------------------------------
2369 // If the store is from an AND mask that leaves the low bits untouched, then
2370 // we can skip the AND operation
2371 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
2372 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
2373 if( progress != NULL ) return progress;
2374
2375 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
2376 if( progress != NULL ) return progress;
2377
2378 // Finally check the default case
2379 return StoreNode::Ideal(phase, can_reshape);
2380 }
2381
2382 //=============================================================================
2383 //------------------------------Identity---------------------------------------
2384 Node *StoreCMNode::Identity( PhaseTransform *phase ) {
2385 // No need to card mark when storing a null ptr
2386 Node* my_store = in(MemNode::OopStore);
2387 if (my_store->is_Store()) {
2388 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) );
2389 if( t1 == TypePtr::NULL_PTR ) {
2390 return in(MemNode::Memory);
2391 }
2392 }
2393 return this;
2394 }
2395
2396 //=============================================================================
2397 //------------------------------Ideal---------------------------------------
2398 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){
2399 Node* progress = StoreNode::Ideal(phase, can_reshape);
2400 if (progress != NULL) return progress;
2401
2402 Node* my_store = in(MemNode::OopStore);
2403 if (my_store->is_MergeMem()) {
2404 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx());
2405 set_req(MemNode::OopStore, mem);
2406 return this;
2407 }
2408
2409 return NULL;
2410 }
2411
2412 //------------------------------Value-----------------------------------------
2413 const Type *StoreCMNode::Value( PhaseTransform *phase ) const {
2414 // Either input is TOP ==> the result is TOP
2415 const Type *t = phase->type( in(MemNode::Memory) );
2416 if( t == Type::TOP ) return Type::TOP;
2417 t = phase->type( in(MemNode::Address) );
2418 if( t == Type::TOP ) return Type::TOP;
2419 t = phase->type( in(MemNode::ValueIn) );
2420 if( t == Type::TOP ) return Type::TOP;
2421 // If extra input is TOP ==> the result is TOP
2422 t = phase->type( in(MemNode::OopStore) );
2423 if( t == Type::TOP ) return Type::TOP;
2424
2425 return StoreNode::Value( phase );
2426 }
2427
2428
2429 //=============================================================================
2430 //----------------------------------SCMemProjNode------------------------------
2431 const Type * SCMemProjNode::Value( PhaseTransform *phase ) const
2432 {
2433 return bottom_type();
2434 }
2435
2436 //=============================================================================
2437 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : Node(5) {
2438 init_req(MemNode::Control, c );
2439 init_req(MemNode::Memory , mem);
2440 init_req(MemNode::Address, adr);
2441 init_req(MemNode::ValueIn, val);
2442 init_req( ExpectedIn, ex );
2443 init_class_id(Class_LoadStore);
2444
2445 }
2446
2447 //=============================================================================
2448 //-------------------------------adr_type--------------------------------------
2449 // Do we Match on this edge index or not? Do not match memory
2450 const TypePtr* ClearArrayNode::adr_type() const {
2451 Node *adr = in(3);
2452 return MemNode::calculate_adr_type(adr->bottom_type());
2453 }
2454
2455 //------------------------------match_edge-------------------------------------
2456 // Do we Match on this edge index or not? Do not match memory
2457 uint ClearArrayNode::match_edge(uint idx) const {
2458 return idx > 1;
2459 }
2460
2461 //------------------------------Identity---------------------------------------
2462 // Clearing a zero length array does nothing
2463 Node *ClearArrayNode::Identity( PhaseTransform *phase ) {
2464 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
2465 }
2466
2467 //------------------------------Idealize---------------------------------------
2468 // Clearing a short array is faster with stores
2469 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape){
2470 const int unit = BytesPerLong;
2471 const TypeX* t = phase->type(in(2))->isa_intptr_t();
2472 if (!t) return NULL;
2473 if (!t->is_con()) return NULL;
2474 intptr_t raw_count = t->get_con();
2475 intptr_t size = raw_count;
2476 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
2477 // Clearing nothing uses the Identity call.
2478 // Negative clears are possible on dead ClearArrays
2479 // (see jck test stmt114.stmt11402.val).
2480 if (size <= 0 || size % unit != 0) return NULL;
2481 intptr_t count = size / unit;
2482 // Length too long; use fast hardware clear
2483 if (size > Matcher::init_array_short_size) return NULL;
2484 Node *mem = in(1);
2485 if( phase->type(mem)==Type::TOP ) return NULL;
2486 Node *adr = in(3);
2487 const Type* at = phase->type(adr);
2488 if( at==Type::TOP ) return NULL;
2489 const TypePtr* atp = at->isa_ptr();
2490 // adjust atp to be the correct array element address type
2491 if (atp == NULL) atp = TypePtr::BOTTOM;
2492 else atp = atp->add_offset(Type::OffsetBot);
2493 // Get base for derived pointer purposes
2494 if( adr->Opcode() != Op_AddP ) Unimplemented();
2495 Node *base = adr->in(1);
2496
2497 Node *zero = phase->makecon(TypeLong::ZERO);
2498 Node *off = phase->MakeConX(BytesPerLong);
2499 mem = new (phase->C, 4) StoreLNode(in(0),mem,adr,atp,zero);
2500 count--;
2501 while( count-- ) {
2502 mem = phase->transform(mem);
2503 adr = phase->transform(new (phase->C, 4) AddPNode(base,adr,off));
2504 mem = new (phase->C, 4) StoreLNode(in(0),mem,adr,atp,zero);
2505 }
2506 return mem;
2507 }
2508
2509 //----------------------------step_through----------------------------------
2510 // Return allocation input memory edge if it is different instance
2511 // or itself if it is the one we are looking for.
2512 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) {
2513 Node* n = *np;
2514 assert(n->is_ClearArray(), "sanity");
2515 intptr_t offset;
2516 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
2517 // This method is called only before Allocate nodes are expanded during
2518 // macro nodes expansion. Before that ClearArray nodes are only generated
2519 // in LibraryCallKit::generate_arraycopy() which follows allocations.
2520 assert(alloc != NULL, "should have allocation");
2521 if (alloc->_idx == instance_id) {
2522 // Can not bypass initialization of the instance we are looking for.
2523 return false;
2524 }
2525 // Otherwise skip it.
2526 InitializeNode* init = alloc->initialization();
2527 if (init != NULL)
2528 *np = init->in(TypeFunc::Memory);
2529 else
2530 *np = alloc->in(TypeFunc::Memory);
2531 return true;
2532 }
2533
2534 //----------------------------clear_memory-------------------------------------
2535 // Generate code to initialize object storage to zero.
2536 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2537 intptr_t start_offset,
2538 Node* end_offset,
2539 PhaseGVN* phase) {
2540 Compile* C = phase->C;
2541 intptr_t offset = start_offset;
2542
2543 int unit = BytesPerLong;
2544 if ((offset % unit) != 0) {
2545 Node* adr = new (C, 4) AddPNode(dest, dest, phase->MakeConX(offset));
2546 adr = phase->transform(adr);
2547 const TypePtr* atp = TypeRawPtr::BOTTOM;
2548 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT);
2549 mem = phase->transform(mem);
2550 offset += BytesPerInt;
2551 }
2552 assert((offset % unit) == 0, "");
2553
2554 // Initialize the remaining stuff, if any, with a ClearArray.
2555 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase);
2556 }
2557
2558 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2559 Node* start_offset,
2560 Node* end_offset,
2561 PhaseGVN* phase) {
2562 if (start_offset == end_offset) {
2563 // nothing to do
2564 return mem;
2565 }
2566
2567 Compile* C = phase->C;
2568 int unit = BytesPerLong;
2569 Node* zbase = start_offset;
2570 Node* zend = end_offset;
2571
2572 // Scale to the unit required by the CPU:
2573 if (!Matcher::init_array_count_is_in_bytes) {
2574 Node* shift = phase->intcon(exact_log2(unit));
2575 zbase = phase->transform( new(C,3) URShiftXNode(zbase, shift) );
2576 zend = phase->transform( new(C,3) URShiftXNode(zend, shift) );
2577 }
2578
2579 Node* zsize = phase->transform( new(C,3) SubXNode(zend, zbase) );
2580 Node* zinit = phase->zerocon((unit == BytesPerLong) ? T_LONG : T_INT);
2581
2582 // Bulk clear double-words
2583 Node* adr = phase->transform( new(C,4) AddPNode(dest, dest, start_offset) );
2584 mem = new (C, 4) ClearArrayNode(ctl, mem, zsize, adr);
2585 return phase->transform(mem);
2586 }
2587
2588 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2589 intptr_t start_offset,
2590 intptr_t end_offset,
2591 PhaseGVN* phase) {
2592 if (start_offset == end_offset) {
2593 // nothing to do
2594 return mem;
2595 }
2596
2597 Compile* C = phase->C;
2598 assert((end_offset % BytesPerInt) == 0, "odd end offset");
2599 intptr_t done_offset = end_offset;
2600 if ((done_offset % BytesPerLong) != 0) {
2601 done_offset -= BytesPerInt;
2602 }
2603 if (done_offset > start_offset) {
2604 mem = clear_memory(ctl, mem, dest,
2605 start_offset, phase->MakeConX(done_offset), phase);
2606 }
2607 if (done_offset < end_offset) { // emit the final 32-bit store
2608 Node* adr = new (C, 4) AddPNode(dest, dest, phase->MakeConX(done_offset));
2609 adr = phase->transform(adr);
2610 const TypePtr* atp = TypeRawPtr::BOTTOM;
2611 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT);
2612 mem = phase->transform(mem);
2613 done_offset += BytesPerInt;
2614 }
2615 assert(done_offset == end_offset, "");
2616 return mem;
2617 }
2618
2619 //=============================================================================
2620 // Do not match memory edge.
2621 uint StrIntrinsicNode::match_edge(uint idx) const {
2622 return idx == 2 || idx == 3;
2623 }
2624
2625 //------------------------------Ideal------------------------------------------
2626 // Return a node which is more "ideal" than the current node. Strip out
2627 // control copies
2628 Node *StrIntrinsicNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2629 if (remove_dead_region(phase, can_reshape)) return this;
2630
2631 Node* mem = phase->transform(in(MemNode::Memory));
2632 // If transformed to a MergeMem, get the desired slice
2633 uint alias_idx = phase->C->get_alias_index(adr_type());
2634 mem = mem->is_MergeMem() ? mem->as_MergeMem()->memory_at(alias_idx) : mem;
2635 if (mem != in(MemNode::Memory))
2636 set_req(MemNode::Memory, mem);
2637 return NULL;
2638 }
2639
2640 //=============================================================================
2641 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
2642 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)),
2643 _adr_type(C->get_adr_type(alias_idx))
2644 {
2645 init_class_id(Class_MemBar);
2646 Node* top = C->top();
2647 init_req(TypeFunc::I_O,top);
2648 init_req(TypeFunc::FramePtr,top);
2649 init_req(TypeFunc::ReturnAdr,top);
2650 if (precedent != NULL)
2651 init_req(TypeFunc::Parms, precedent);
2652 }
2653
2654 //------------------------------cmp--------------------------------------------
2655 uint MemBarNode::hash() const { return NO_HASH; }
2656 uint MemBarNode::cmp( const Node &n ) const {
2657 return (&n == this); // Always fail except on self
2658 }
2659
2660 //------------------------------make-------------------------------------------
2661 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
2662 int len = Precedent + (pn == NULL? 0: 1);
2663 switch (opcode) {
2664 case Op_MemBarAcquire: return new(C, len) MemBarAcquireNode(C, atp, pn);
2665 case Op_MemBarRelease: return new(C, len) MemBarReleaseNode(C, atp, pn);
2666 case Op_MemBarVolatile: return new(C, len) MemBarVolatileNode(C, atp, pn);
2667 case Op_MemBarCPUOrder: return new(C, len) MemBarCPUOrderNode(C, atp, pn);
2668 case Op_Initialize: return new(C, len) InitializeNode(C, atp, pn);
2669 default: ShouldNotReachHere(); return NULL;
2670 }
2671 }
2672
2673 //------------------------------Ideal------------------------------------------
2674 // Return a node which is more "ideal" than the current node. Strip out
2675 // control copies
2676 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2677 if (remove_dead_region(phase, can_reshape)) return this;
2678
2679 // Eliminate volatile MemBars for scalar replaced objects.
2680 if (can_reshape && req() == (Precedent+1) &&
2681 (Opcode() == Op_MemBarAcquire || Opcode() == Op_MemBarVolatile)) {
2682 // Volatile field loads and stores.
2683 Node* my_mem = in(MemBarNode::Precedent);
2684 if (my_mem != NULL && my_mem->is_Mem()) {
2685 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
2686 // Check for scalar replaced object reference.
2687 if( t_oop != NULL && t_oop->is_known_instance_field() &&
2688 t_oop->offset() != Type::OffsetBot &&
2689 t_oop->offset() != Type::OffsetTop) {
2690 // Replace MemBar projections by its inputs.
2691 PhaseIterGVN* igvn = phase->is_IterGVN();
2692 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
2693 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
2694 // Must return either the original node (now dead) or a new node
2695 // (Do not return a top here, since that would break the uniqueness of top.)
2696 return new (phase->C, 1) ConINode(TypeInt::ZERO);
2697 }
2698 }
2699 }
2700 return NULL;
2701 }
2702
2703 //------------------------------Value------------------------------------------
2704 const Type *MemBarNode::Value( PhaseTransform *phase ) const {
2705 if( !in(0) ) return Type::TOP;
2706 if( phase->type(in(0)) == Type::TOP )
2707 return Type::TOP;
2708 return TypeTuple::MEMBAR;
2709 }
2710
2711 //------------------------------match------------------------------------------
2712 // Construct projections for memory.
2713 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) {
2714 switch (proj->_con) {
2715 case TypeFunc::Control:
2716 case TypeFunc::Memory:
2717 return new (m->C, 1) MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
2718 }
2719 ShouldNotReachHere();
2720 return NULL;
2721 }
2722
2723 //===========================InitializeNode====================================
2724 // SUMMARY:
2725 // This node acts as a memory barrier on raw memory, after some raw stores.
2726 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
2727 // The Initialize can 'capture' suitably constrained stores as raw inits.
2728 // It can coalesce related raw stores into larger units (called 'tiles').
2729 // It can avoid zeroing new storage for memory units which have raw inits.
2730 // At macro-expansion, it is marked 'complete', and does not optimize further.
2731 //
2732 // EXAMPLE:
2733 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
2734 // ctl = incoming control; mem* = incoming memory
2735 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
2736 // First allocate uninitialized memory and fill in the header:
2737 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
2738 // ctl := alloc.Control; mem* := alloc.Memory*
2739 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
2740 // Then initialize to zero the non-header parts of the raw memory block:
2741 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
2742 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
2743 // After the initialize node executes, the object is ready for service:
2744 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
2745 // Suppose its body is immediately initialized as {1,2}:
2746 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
2747 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
2748 // mem.SLICE(#short[*]) := store2
2749 //
2750 // DETAILS:
2751 // An InitializeNode collects and isolates object initialization after
2752 // an AllocateNode and before the next possible safepoint. As a
2753 // memory barrier (MemBarNode), it keeps critical stores from drifting
2754 // down past any safepoint or any publication of the allocation.
2755 // Before this barrier, a newly-allocated object may have uninitialized bits.
2756 // After this barrier, it may be treated as a real oop, and GC is allowed.
2757 //
2758 // The semantics of the InitializeNode include an implicit zeroing of
2759 // the new object from object header to the end of the object.
2760 // (The object header and end are determined by the AllocateNode.)
2761 //
2762 // Certain stores may be added as direct inputs to the InitializeNode.
2763 // These stores must update raw memory, and they must be to addresses
2764 // derived from the raw address produced by AllocateNode, and with
2765 // a constant offset. They must be ordered by increasing offset.
2766 // The first one is at in(RawStores), the last at in(req()-1).
2767 // Unlike most memory operations, they are not linked in a chain,
2768 // but are displayed in parallel as users of the rawmem output of
2769 // the allocation.
2770 //
2771 // (See comments in InitializeNode::capture_store, which continue
2772 // the example given above.)
2773 //
2774 // When the associated Allocate is macro-expanded, the InitializeNode
2775 // may be rewritten to optimize collected stores. A ClearArrayNode
2776 // may also be created at that point to represent any required zeroing.
2777 // The InitializeNode is then marked 'complete', prohibiting further
2778 // capturing of nearby memory operations.
2779 //
2780 // During macro-expansion, all captured initializations which store
2781 // constant values of 32 bits or smaller are coalesced (if advantageous)
2782 // into larger 'tiles' 32 or 64 bits. This allows an object to be
2783 // initialized in fewer memory operations. Memory words which are
2784 // covered by neither tiles nor non-constant stores are pre-zeroed
2785 // by explicit stores of zero. (The code shape happens to do all
2786 // zeroing first, then all other stores, with both sequences occurring
2787 // in order of ascending offsets.)
2788 //
2789 // Alternatively, code may be inserted between an AllocateNode and its
2790 // InitializeNode, to perform arbitrary initialization of the new object.
2791 // E.g., the object copying intrinsics insert complex data transfers here.
2792 // The initialization must then be marked as 'complete' disable the
2793 // built-in zeroing semantics and the collection of initializing stores.
2794 //
2795 // While an InitializeNode is incomplete, reads from the memory state
2796 // produced by it are optimizable if they match the control edge and
2797 // new oop address associated with the allocation/initialization.
2798 // They return a stored value (if the offset matches) or else zero.
2799 // A write to the memory state, if it matches control and address,
2800 // and if it is to a constant offset, may be 'captured' by the
2801 // InitializeNode. It is cloned as a raw memory operation and rewired
2802 // inside the initialization, to the raw oop produced by the allocation.
2803 // Operations on addresses which are provably distinct (e.g., to
2804 // other AllocateNodes) are allowed to bypass the initialization.
2805 //
2806 // The effect of all this is to consolidate object initialization
2807 // (both arrays and non-arrays, both piecewise and bulk) into a
2808 // single location, where it can be optimized as a unit.
2809 //
2810 // Only stores with an offset less than TrackedInitializationLimit words
2811 // will be considered for capture by an InitializeNode. This puts a
2812 // reasonable limit on the complexity of optimized initializations.
2813
2814 //---------------------------InitializeNode------------------------------------
2815 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
2816 : _is_complete(false),
2817 MemBarNode(C, adr_type, rawoop)
2818 {
2819 init_class_id(Class_Initialize);
2820
2821 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
2822 assert(in(RawAddress) == rawoop, "proper init");
2823 // Note: allocation() can be NULL, for secondary initialization barriers
2824 }
2825
2826 // Since this node is not matched, it will be processed by the
2827 // register allocator. Declare that there are no constraints
2828 // on the allocation of the RawAddress edge.
2829 const RegMask &InitializeNode::in_RegMask(uint idx) const {
2830 // This edge should be set to top, by the set_complete. But be conservative.
2831 if (idx == InitializeNode::RawAddress)
2832 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
2833 return RegMask::Empty;
2834 }
2835
2836 Node* InitializeNode::memory(uint alias_idx) {
2837 Node* mem = in(Memory);
2838 if (mem->is_MergeMem()) {
2839 return mem->as_MergeMem()->memory_at(alias_idx);
2840 } else {
2841 // incoming raw memory is not split
2842 return mem;
2843 }
2844 }
2845
2846 bool InitializeNode::is_non_zero() {
2847 if (is_complete()) return false;
2848 remove_extra_zeroes();
2849 return (req() > RawStores);
2850 }
2851
2852 void InitializeNode::set_complete(PhaseGVN* phase) {
2853 assert(!is_complete(), "caller responsibility");
2854 _is_complete = true;
2855
2856 // After this node is complete, it contains a bunch of
2857 // raw-memory initializations. There is no need for
2858 // it to have anything to do with non-raw memory effects.
2859 // Therefore, tell all non-raw users to re-optimize themselves,
2860 // after skipping the memory effects of this initialization.
2861 PhaseIterGVN* igvn = phase->is_IterGVN();
2862 if (igvn) igvn->add_users_to_worklist(this);
2863 }
2864
2865 // convenience function
2866 // return false if the init contains any stores already
2867 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
2868 InitializeNode* init = initialization();
2869 if (init == NULL || init->is_complete()) return false;
2870 init->remove_extra_zeroes();
2871 // for now, if this allocation has already collected any inits, bail:
2872 if (init->is_non_zero()) return false;
2873 init->set_complete(phase);
2874 return true;
2875 }
2876
2877 void InitializeNode::remove_extra_zeroes() {
2878 if (req() == RawStores) return;
2879 Node* zmem = zero_memory();
2880 uint fill = RawStores;
2881 for (uint i = fill; i < req(); i++) {
2882 Node* n = in(i);
2883 if (n->is_top() || n == zmem) continue; // skip
2884 if (fill < i) set_req(fill, n); // compact
2885 ++fill;
2886 }
2887 // delete any empty spaces created:
2888 while (fill < req()) {
2889 del_req(fill);
2890 }
2891 }
2892
2893 // Helper for remembering which stores go with which offsets.
2894 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) {
2895 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
2896 intptr_t offset = -1;
2897 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
2898 phase, offset);
2899 if (base == NULL) return -1; // something is dead,
2900 if (offset < 0) return -1; // dead, dead
2901 return offset;
2902 }
2903
2904 // Helper for proving that an initialization expression is
2905 // "simple enough" to be folded into an object initialization.
2906 // Attempts to prove that a store's initial value 'n' can be captured
2907 // within the initialization without creating a vicious cycle, such as:
2908 // { Foo p = new Foo(); p.next = p; }
2909 // True for constants and parameters and small combinations thereof.
2910 bool InitializeNode::detect_init_independence(Node* n,
2911 bool st_is_pinned,
2912 int& count) {
2913 if (n == NULL) return true; // (can this really happen?)
2914 if (n->is_Proj()) n = n->in(0);
2915 if (n == this) return false; // found a cycle
2916 if (n->is_Con()) return true;
2917 if (n->is_Start()) return true; // params, etc., are OK
2918 if (n->is_Root()) return true; // even better
2919
2920 Node* ctl = n->in(0);
2921 if (ctl != NULL && !ctl->is_top()) {
2922 if (ctl->is_Proj()) ctl = ctl->in(0);
2923 if (ctl == this) return false;
2924
2925 // If we already know that the enclosing memory op is pinned right after
2926 // the init, then any control flow that the store has picked up
2927 // must have preceded the init, or else be equal to the init.
2928 // Even after loop optimizations (which might change control edges)
2929 // a store is never pinned *before* the availability of its inputs.
2930 if (!MemNode::all_controls_dominate(n, this))
2931 return false; // failed to prove a good control
2932
2933 }
2934
2935 // Check data edges for possible dependencies on 'this'.
2936 if ((count += 1) > 20) return false; // complexity limit
2937 for (uint i = 1; i < n->req(); i++) {
2938 Node* m = n->in(i);
2939 if (m == NULL || m == n || m->is_top()) continue;
2940 uint first_i = n->find_edge(m);
2941 if (i != first_i) continue; // process duplicate edge just once
2942 if (!detect_init_independence(m, st_is_pinned, count)) {
2943 return false;
2944 }
2945 }
2946
2947 return true;
2948 }
2949
2950 // Here are all the checks a Store must pass before it can be moved into
2951 // an initialization. Returns zero if a check fails.
2952 // On success, returns the (constant) offset to which the store applies,
2953 // within the initialized memory.
2954 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase) {
2955 const int FAIL = 0;
2956 if (st->req() != MemNode::ValueIn + 1)
2957 return FAIL; // an inscrutable StoreNode (card mark?)
2958 Node* ctl = st->in(MemNode::Control);
2959 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this))
2960 return FAIL; // must be unconditional after the initialization
2961 Node* mem = st->in(MemNode::Memory);
2962 if (!(mem->is_Proj() && mem->in(0) == this))
2963 return FAIL; // must not be preceded by other stores
2964 Node* adr = st->in(MemNode::Address);
2965 intptr_t offset;
2966 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
2967 if (alloc == NULL)
2968 return FAIL; // inscrutable address
2969 if (alloc != allocation())
2970 return FAIL; // wrong allocation! (store needs to float up)
2971 Node* val = st->in(MemNode::ValueIn);
2972 int complexity_count = 0;
2973 if (!detect_init_independence(val, true, complexity_count))
2974 return FAIL; // stored value must be 'simple enough'
2975
2976 return offset; // success
2977 }
2978
2979 // Find the captured store in(i) which corresponds to the range
2980 // [start..start+size) in the initialized object.
2981 // If there is one, return its index i. If there isn't, return the
2982 // negative of the index where it should be inserted.
2983 // Return 0 if the queried range overlaps an initialization boundary
2984 // or if dead code is encountered.
2985 // If size_in_bytes is zero, do not bother with overlap checks.
2986 int InitializeNode::captured_store_insertion_point(intptr_t start,
2987 int size_in_bytes,
2988 PhaseTransform* phase) {
2989 const int FAIL = 0, MAX_STORE = BytesPerLong;
2990
2991 if (is_complete())
2992 return FAIL; // arraycopy got here first; punt
2993
2994 assert(allocation() != NULL, "must be present");
2995
2996 // no negatives, no header fields:
2997 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
2998
2999 // after a certain size, we bail out on tracking all the stores:
3000 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3001 if (start >= ti_limit) return FAIL;
3002
3003 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
3004 if (i >= limit) return -(int)i; // not found; here is where to put it
3005
3006 Node* st = in(i);
3007 intptr_t st_off = get_store_offset(st, phase);
3008 if (st_off < 0) {
3009 if (st != zero_memory()) {
3010 return FAIL; // bail out if there is dead garbage
3011 }
3012 } else if (st_off > start) {
3013 // ...we are done, since stores are ordered
3014 if (st_off < start + size_in_bytes) {
3015 return FAIL; // the next store overlaps
3016 }
3017 return -(int)i; // not found; here is where to put it
3018 } else if (st_off < start) {
3019 if (size_in_bytes != 0 &&
3020 start < st_off + MAX_STORE &&
3021 start < st_off + st->as_Store()->memory_size()) {
3022 return FAIL; // the previous store overlaps
3023 }
3024 } else {
3025 if (size_in_bytes != 0 &&
3026 st->as_Store()->memory_size() != size_in_bytes) {
3027 return FAIL; // mismatched store size
3028 }
3029 return i;
3030 }
3031
3032 ++i;
3033 }
3034 }
3035
3036 // Look for a captured store which initializes at the offset 'start'
3037 // with the given size. If there is no such store, and no other
3038 // initialization interferes, then return zero_memory (the memory
3039 // projection of the AllocateNode).
3040 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
3041 PhaseTransform* phase) {
3042 assert(stores_are_sane(phase), "");
3043 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3044 if (i == 0) {
3045 return NULL; // something is dead
3046 } else if (i < 0) {
3047 return zero_memory(); // just primordial zero bits here
3048 } else {
3049 Node* st = in(i); // here is the store at this position
3050 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
3051 return st;
3052 }
3053 }
3054
3055 // Create, as a raw pointer, an address within my new object at 'offset'.
3056 Node* InitializeNode::make_raw_address(intptr_t offset,
3057 PhaseTransform* phase) {
3058 Node* addr = in(RawAddress);
3059 if (offset != 0) {
3060 Compile* C = phase->C;
3061 addr = phase->transform( new (C, 4) AddPNode(C->top(), addr,
3062 phase->MakeConX(offset)) );
3063 }
3064 return addr;
3065 }
3066
3067 // Clone the given store, converting it into a raw store
3068 // initializing a field or element of my new object.
3069 // Caller is responsible for retiring the original store,
3070 // with subsume_node or the like.
3071 //
3072 // From the example above InitializeNode::InitializeNode,
3073 // here are the old stores to be captured:
3074 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3075 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3076 //
3077 // Here is the changed code; note the extra edges on init:
3078 // alloc = (Allocate ...)
3079 // rawoop = alloc.RawAddress
3080 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
3081 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
3082 // init = (Initialize alloc.Control alloc.Memory rawoop
3083 // rawstore1 rawstore2)
3084 //
3085 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
3086 PhaseTransform* phase) {
3087 assert(stores_are_sane(phase), "");
3088
3089 if (start < 0) return NULL;
3090 assert(can_capture_store(st, phase) == start, "sanity");
3091
3092 Compile* C = phase->C;
3093 int size_in_bytes = st->memory_size();
3094 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3095 if (i == 0) return NULL; // bail out
3096 Node* prev_mem = NULL; // raw memory for the captured store
3097 if (i > 0) {
3098 prev_mem = in(i); // there is a pre-existing store under this one
3099 set_req(i, C->top()); // temporarily disconnect it
3100 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
3101 } else {
3102 i = -i; // no pre-existing store
3103 prev_mem = zero_memory(); // a slice of the newly allocated object
3104 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
3105 set_req(--i, C->top()); // reuse this edge; it has been folded away
3106 else
3107 ins_req(i, C->top()); // build a new edge
3108 }
3109 Node* new_st = st->clone();
3110 new_st->set_req(MemNode::Control, in(Control));
3111 new_st->set_req(MemNode::Memory, prev_mem);
3112 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
3113 new_st = phase->transform(new_st);
3114
3115 // At this point, new_st might have swallowed a pre-existing store
3116 // at the same offset, or perhaps new_st might have disappeared,
3117 // if it redundantly stored the same value (or zero to fresh memory).
3118
3119 // In any case, wire it in:
3120 set_req(i, new_st);
3121
3122 // The caller may now kill the old guy.
3123 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
3124 assert(check_st == new_st || check_st == NULL, "must be findable");
3125 assert(!is_complete(), "");
3126 return new_st;
3127 }
3128
3129 static bool store_constant(jlong* tiles, int num_tiles,
3130 intptr_t st_off, int st_size,
3131 jlong con) {
3132 if ((st_off & (st_size-1)) != 0)
3133 return false; // strange store offset (assume size==2**N)
3134 address addr = (address)tiles + st_off;
3135 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
3136 switch (st_size) {
3137 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
3138 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
3139 case sizeof(jint): *(jint*) addr = (jint) con; break;
3140 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
3141 default: return false; // strange store size (detect size!=2**N here)
3142 }
3143 return true; // return success to caller
3144 }
3145
3146 // Coalesce subword constants into int constants and possibly
3147 // into long constants. The goal, if the CPU permits,
3148 // is to initialize the object with a small number of 64-bit tiles.
3149 // Also, convert floating-point constants to bit patterns.
3150 // Non-constants are not relevant to this pass.
3151 //
3152 // In terms of the running example on InitializeNode::InitializeNode
3153 // and InitializeNode::capture_store, here is the transformation
3154 // of rawstore1 and rawstore2 into rawstore12:
3155 // alloc = (Allocate ...)
3156 // rawoop = alloc.RawAddress
3157 // tile12 = 0x00010002
3158 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
3159 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
3160 //
3161 void
3162 InitializeNode::coalesce_subword_stores(intptr_t header_size,
3163 Node* size_in_bytes,
3164 PhaseGVN* phase) {
3165 Compile* C = phase->C;
3166
3167 assert(stores_are_sane(phase), "");
3168 // Note: After this pass, they are not completely sane,
3169 // since there may be some overlaps.
3170
3171 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
3172
3173 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3174 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
3175 size_limit = MIN2(size_limit, ti_limit);
3176 size_limit = align_size_up(size_limit, BytesPerLong);
3177 int num_tiles = size_limit / BytesPerLong;
3178
3179 // allocate space for the tile map:
3180 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
3181 jlong tiles_buf[small_len];
3182 Node* nodes_buf[small_len];
3183 jlong inits_buf[small_len];
3184 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
3185 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3186 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
3187 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
3188 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
3189 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3190 // tiles: exact bitwise model of all primitive constants
3191 // nodes: last constant-storing node subsumed into the tiles model
3192 // inits: which bytes (in each tile) are touched by any initializations
3193
3194 //// Pass A: Fill in the tile model with any relevant stores.
3195
3196 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
3197 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
3198 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
3199 Node* zmem = zero_memory(); // initially zero memory state
3200 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3201 Node* st = in(i);
3202 intptr_t st_off = get_store_offset(st, phase);
3203
3204 // Figure out the store's offset and constant value:
3205 if (st_off < header_size) continue; //skip (ignore header)
3206 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
3207 int st_size = st->as_Store()->memory_size();
3208 if (st_off + st_size > size_limit) break;
3209
3210 // Record which bytes are touched, whether by constant or not.
3211 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
3212 continue; // skip (strange store size)
3213
3214 const Type* val = phase->type(st->in(MemNode::ValueIn));
3215 if (!val->singleton()) continue; //skip (non-con store)
3216 BasicType type = val->basic_type();
3217
3218 jlong con = 0;
3219 switch (type) {
3220 case T_INT: con = val->is_int()->get_con(); break;
3221 case T_LONG: con = val->is_long()->get_con(); break;
3222 case T_FLOAT: con = jint_cast(val->getf()); break;
3223 case T_DOUBLE: con = jlong_cast(val->getd()); break;
3224 default: continue; //skip (odd store type)
3225 }
3226
3227 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
3228 st->Opcode() == Op_StoreL) {
3229 continue; // This StoreL is already optimal.
3230 }
3231
3232 // Store down the constant.
3233 store_constant(tiles, num_tiles, st_off, st_size, con);
3234
3235 intptr_t j = st_off >> LogBytesPerLong;
3236
3237 if (type == T_INT && st_size == BytesPerInt
3238 && (st_off & BytesPerInt) == BytesPerInt) {
3239 jlong lcon = tiles[j];
3240 if (!Matcher::isSimpleConstant64(lcon) &&
3241 st->Opcode() == Op_StoreI) {
3242 // This StoreI is already optimal by itself.
3243 jint* intcon = (jint*) &tiles[j];
3244 intcon[1] = 0; // undo the store_constant()
3245
3246 // If the previous store is also optimal by itself, back up and
3247 // undo the action of the previous loop iteration... if we can.
3248 // But if we can't, just let the previous half take care of itself.
3249 st = nodes[j];
3250 st_off -= BytesPerInt;
3251 con = intcon[0];
3252 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) {
3253 assert(st_off >= header_size, "still ignoring header");
3254 assert(get_store_offset(st, phase) == st_off, "must be");
3255 assert(in(i-1) == zmem, "must be");
3256 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
3257 assert(con == tcon->is_int()->get_con(), "must be");
3258 // Undo the effects of the previous loop trip, which swallowed st:
3259 intcon[0] = 0; // undo store_constant()
3260 set_req(i-1, st); // undo set_req(i, zmem)
3261 nodes[j] = NULL; // undo nodes[j] = st
3262 --old_subword; // undo ++old_subword
3263 }
3264 continue; // This StoreI is already optimal.
3265 }
3266 }
3267
3268 // This store is not needed.
3269 set_req(i, zmem);
3270 nodes[j] = st; // record for the moment
3271 if (st_size < BytesPerLong) // something has changed
3272 ++old_subword; // includes int/float, but who's counting...
3273 else ++old_long;
3274 }
3275
3276 if ((old_subword + old_long) == 0)
3277 return; // nothing more to do
3278
3279 //// Pass B: Convert any non-zero tiles into optimal constant stores.
3280 // Be sure to insert them before overlapping non-constant stores.
3281 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
3282 for (int j = 0; j < num_tiles; j++) {
3283 jlong con = tiles[j];
3284 jlong init = inits[j];
3285 if (con == 0) continue;
3286 jint con0, con1; // split the constant, address-wise
3287 jint init0, init1; // split the init map, address-wise
3288 { union { jlong con; jint intcon[2]; } u;
3289 u.con = con;
3290 con0 = u.intcon[0];
3291 con1 = u.intcon[1];
3292 u.con = init;
3293 init0 = u.intcon[0];
3294 init1 = u.intcon[1];
3295 }
3296
3297 Node* old = nodes[j];
3298 assert(old != NULL, "need the prior store");
3299 intptr_t offset = (j * BytesPerLong);
3300
3301 bool split = !Matcher::isSimpleConstant64(con);
3302
3303 if (offset < header_size) {
3304 assert(offset + BytesPerInt >= header_size, "second int counts");
3305 assert(*(jint*)&tiles[j] == 0, "junk in header");
3306 split = true; // only the second word counts
3307 // Example: int a[] = { 42 ... }
3308 } else if (con0 == 0 && init0 == -1) {
3309 split = true; // first word is covered by full inits
3310 // Example: int a[] = { ... foo(), 42 ... }
3311 } else if (con1 == 0 && init1 == -1) {
3312 split = true; // second word is covered by full inits
3313 // Example: int a[] = { ... 42, foo() ... }
3314 }
3315
3316 // Here's a case where init0 is neither 0 nor -1:
3317 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
3318 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
3319 // In this case the tile is not split; it is (jlong)42.
3320 // The big tile is stored down, and then the foo() value is inserted.
3321 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
3322
3323 Node* ctl = old->in(MemNode::Control);
3324 Node* adr = make_raw_address(offset, phase);
3325 const TypePtr* atp = TypeRawPtr::BOTTOM;
3326
3327 // One or two coalesced stores to plop down.
3328 Node* st[2];
3329 intptr_t off[2];
3330 int nst = 0;
3331 if (!split) {
3332 ++new_long;
3333 off[nst] = offset;
3334 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3335 phase->longcon(con), T_LONG);
3336 } else {
3337 // Omit either if it is a zero.
3338 if (con0 != 0) {
3339 ++new_int;
3340 off[nst] = offset;
3341 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3342 phase->intcon(con0), T_INT);
3343 }
3344 if (con1 != 0) {
3345 ++new_int;
3346 offset += BytesPerInt;
3347 adr = make_raw_address(offset, phase);
3348 off[nst] = offset;
3349 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3350 phase->intcon(con1), T_INT);
3351 }
3352 }
3353
3354 // Insert second store first, then the first before the second.
3355 // Insert each one just before any overlapping non-constant stores.
3356 while (nst > 0) {
3357 Node* st1 = st[--nst];
3358 C->copy_node_notes_to(st1, old);
3359 st1 = phase->transform(st1);
3360 offset = off[nst];
3361 assert(offset >= header_size, "do not smash header");
3362 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
3363 guarantee(ins_idx != 0, "must re-insert constant store");
3364 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
3365 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
3366 set_req(--ins_idx, st1);
3367 else
3368 ins_req(ins_idx, st1);
3369 }
3370 }
3371
3372 if (PrintCompilation && WizardMode)
3373 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
3374 old_subword, old_long, new_int, new_long);
3375 if (C->log() != NULL)
3376 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
3377 old_subword, old_long, new_int, new_long);
3378
3379 // Clean up any remaining occurrences of zmem:
3380 remove_extra_zeroes();
3381 }
3382
3383 // Explore forward from in(start) to find the first fully initialized
3384 // word, and return its offset. Skip groups of subword stores which
3385 // together initialize full words. If in(start) is itself part of a
3386 // fully initialized word, return the offset of in(start). If there
3387 // are no following full-word stores, or if something is fishy, return
3388 // a negative value.
3389 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
3390 int int_map = 0;
3391 intptr_t int_map_off = 0;
3392 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
3393
3394 for (uint i = start, limit = req(); i < limit; i++) {
3395 Node* st = in(i);
3396
3397 intptr_t st_off = get_store_offset(st, phase);
3398 if (st_off < 0) break; // return conservative answer
3399
3400 int st_size = st->as_Store()->memory_size();
3401 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
3402 return st_off; // we found a complete word init
3403 }
3404
3405 // update the map:
3406
3407 intptr_t this_int_off = align_size_down(st_off, BytesPerInt);
3408 if (this_int_off != int_map_off) {
3409 // reset the map:
3410 int_map = 0;
3411 int_map_off = this_int_off;
3412 }
3413
3414 int subword_off = st_off - this_int_off;
3415 int_map |= right_n_bits(st_size) << subword_off;
3416 if ((int_map & FULL_MAP) == FULL_MAP) {
3417 return this_int_off; // we found a complete word init
3418 }
3419
3420 // Did this store hit or cross the word boundary?
3421 intptr_t next_int_off = align_size_down(st_off + st_size, BytesPerInt);
3422 if (next_int_off == this_int_off + BytesPerInt) {
3423 // We passed the current int, without fully initializing it.
3424 int_map_off = next_int_off;
3425 int_map >>= BytesPerInt;
3426 } else if (next_int_off > this_int_off + BytesPerInt) {
3427 // We passed the current and next int.
3428 return this_int_off + BytesPerInt;
3429 }
3430 }
3431
3432 return -1;
3433 }
3434
3435
3436 // Called when the associated AllocateNode is expanded into CFG.
3437 // At this point, we may perform additional optimizations.
3438 // Linearize the stores by ascending offset, to make memory
3439 // activity as coherent as possible.
3440 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
3441 intptr_t header_size,
3442 Node* size_in_bytes,
3443 PhaseGVN* phase) {
3444 assert(!is_complete(), "not already complete");
3445 assert(stores_are_sane(phase), "");
3446 assert(allocation() != NULL, "must be present");
3447
3448 remove_extra_zeroes();
3449
3450 if (ReduceFieldZeroing || ReduceBulkZeroing)
3451 // reduce instruction count for common initialization patterns
3452 coalesce_subword_stores(header_size, size_in_bytes, phase);
3453
3454 Node* zmem = zero_memory(); // initially zero memory state
3455 Node* inits = zmem; // accumulating a linearized chain of inits
3456 #ifdef ASSERT
3457 intptr_t first_offset = allocation()->minimum_header_size();
3458 intptr_t last_init_off = first_offset; // previous init offset
3459 intptr_t last_init_end = first_offset; // previous init offset+size
3460 intptr_t last_tile_end = first_offset; // previous tile offset+size
3461 #endif
3462 intptr_t zeroes_done = header_size;
3463
3464 bool do_zeroing = true; // we might give up if inits are very sparse
3465 int big_init_gaps = 0; // how many large gaps have we seen?
3466
3467 if (ZeroTLAB) do_zeroing = false;
3468 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
3469
3470 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3471 Node* st = in(i);
3472 intptr_t st_off = get_store_offset(st, phase);
3473 if (st_off < 0)
3474 break; // unknown junk in the inits
3475 if (st->in(MemNode::Memory) != zmem)
3476 break; // complicated store chains somehow in list
3477
3478 int st_size = st->as_Store()->memory_size();
3479 intptr_t next_init_off = st_off + st_size;
3480
3481 if (do_zeroing && zeroes_done < next_init_off) {
3482 // See if this store needs a zero before it or under it.
3483 intptr_t zeroes_needed = st_off;
3484
3485 if (st_size < BytesPerInt) {
3486 // Look for subword stores which only partially initialize words.
3487 // If we find some, we must lay down some word-level zeroes first,
3488 // underneath the subword stores.
3489 //
3490 // Examples:
3491 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
3492 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
3493 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
3494 //
3495 // Note: coalesce_subword_stores may have already done this,
3496 // if it was prompted by constant non-zero subword initializers.
3497 // But this case can still arise with non-constant stores.
3498
3499 intptr_t next_full_store = find_next_fullword_store(i, phase);
3500
3501 // In the examples above:
3502 // in(i) p q r s x y z
3503 // st_off 12 13 14 15 12 13 14
3504 // st_size 1 1 1 1 1 1 1
3505 // next_full_s. 12 16 16 16 16 16 16
3506 // z's_done 12 16 16 16 12 16 12
3507 // z's_needed 12 16 16 16 16 16 16
3508 // zsize 0 0 0 0 4 0 4
3509 if (next_full_store < 0) {
3510 // Conservative tack: Zero to end of current word.
3511 zeroes_needed = align_size_up(zeroes_needed, BytesPerInt);
3512 } else {
3513 // Zero to beginning of next fully initialized word.
3514 // Or, don't zero at all, if we are already in that word.
3515 assert(next_full_store >= zeroes_needed, "must go forward");
3516 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
3517 zeroes_needed = next_full_store;
3518 }
3519 }
3520
3521 if (zeroes_needed > zeroes_done) {
3522 intptr_t zsize = zeroes_needed - zeroes_done;
3523 // Do some incremental zeroing on rawmem, in parallel with inits.
3524 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3525 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3526 zeroes_done, zeroes_needed,
3527 phase);
3528 zeroes_done = zeroes_needed;
3529 if (zsize > Matcher::init_array_short_size && ++big_init_gaps > 2)
3530 do_zeroing = false; // leave the hole, next time
3531 }
3532 }
3533
3534 // Collect the store and move on:
3535 st->set_req(MemNode::Memory, inits);
3536 inits = st; // put it on the linearized chain
3537 set_req(i, zmem); // unhook from previous position
3538
3539 if (zeroes_done == st_off)
3540 zeroes_done = next_init_off;
3541
3542 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
3543
3544 #ifdef ASSERT
3545 // Various order invariants. Weaker than stores_are_sane because
3546 // a large constant tile can be filled in by smaller non-constant stores.
3547 assert(st_off >= last_init_off, "inits do not reverse");
3548 last_init_off = st_off;
3549 const Type* val = NULL;
3550 if (st_size >= BytesPerInt &&
3551 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
3552 (int)val->basic_type() < (int)T_OBJECT) {
3553 assert(st_off >= last_tile_end, "tiles do not overlap");
3554 assert(st_off >= last_init_end, "tiles do not overwrite inits");
3555 last_tile_end = MAX2(last_tile_end, next_init_off);
3556 } else {
3557 intptr_t st_tile_end = align_size_up(next_init_off, BytesPerLong);
3558 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
3559 assert(st_off >= last_init_end, "inits do not overlap");
3560 last_init_end = next_init_off; // it's a non-tile
3561 }
3562 #endif //ASSERT
3563 }
3564
3565 remove_extra_zeroes(); // clear out all the zmems left over
3566 add_req(inits);
3567
3568 if (!ZeroTLAB) {
3569 // If anything remains to be zeroed, zero it all now.
3570 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3571 // if it is the last unused 4 bytes of an instance, forget about it
3572 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
3573 if (zeroes_done + BytesPerLong >= size_limit) {
3574 assert(allocation() != NULL, "");
3575 if (allocation()->Opcode() == Op_Allocate) {
3576 Node* klass_node = allocation()->in(AllocateNode::KlassNode);
3577 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass();
3578 if (zeroes_done == k->layout_helper())
3579 zeroes_done = size_limit;
3580 }
3581 }
3582 if (zeroes_done < size_limit) {
3583 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3584 zeroes_done, size_in_bytes, phase);
3585 }
3586 }
3587
3588 set_complete(phase);
3589 return rawmem;
3590 }
3591
3592
3593 #ifdef ASSERT
3594 bool InitializeNode::stores_are_sane(PhaseTransform* phase) {
3595 if (is_complete())
3596 return true; // stores could be anything at this point
3597 assert(allocation() != NULL, "must be present");
3598 intptr_t last_off = allocation()->minimum_header_size();
3599 for (uint i = InitializeNode::RawStores; i < req(); i++) {
3600 Node* st = in(i);
3601 intptr_t st_off = get_store_offset(st, phase);
3602 if (st_off < 0) continue; // ignore dead garbage
3603 if (last_off > st_off) {
3604 tty->print_cr("*** bad store offset at %d: %d > %d", i, last_off, st_off);
3605 this->dump(2);
3606 assert(false, "ascending store offsets");
3607 return false;
3608 }
3609 last_off = st_off + st->as_Store()->memory_size();
3610 }
3611 return true;
3612 }
3613 #endif //ASSERT
3614
3615
3616
3617
3618 //============================MergeMemNode=====================================
3619 //
3620 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
3621 // contributing store or call operations. Each contributor provides the memory
3622 // state for a particular "alias type" (see Compile::alias_type). For example,
3623 // if a MergeMem has an input X for alias category #6, then any memory reference
3624 // to alias category #6 may use X as its memory state input, as an exact equivalent
3625 // to using the MergeMem as a whole.
3626 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
3627 //
3628 // (Here, the <N> notation gives the index of the relevant adr_type.)
3629 //
3630 // In one special case (and more cases in the future), alias categories overlap.
3631 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
3632 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
3633 // it is exactly equivalent to that state W:
3634 // MergeMem(<Bot>: W) <==> W
3635 //
3636 // Usually, the merge has more than one input. In that case, where inputs
3637 // overlap (i.e., one is Bot), the narrower alias type determines the memory
3638 // state for that type, and the wider alias type (Bot) fills in everywhere else:
3639 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
3640 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
3641 //
3642 // A merge can take a "wide" memory state as one of its narrow inputs.
3643 // This simply means that the merge observes out only the relevant parts of
3644 // the wide input. That is, wide memory states arriving at narrow merge inputs
3645 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
3646 //
3647 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
3648 // and that memory slices "leak through":
3649 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
3650 //
3651 // But, in such a cascade, repeated memory slices can "block the leak":
3652 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
3653 //
3654 // In the last example, Y is not part of the combined memory state of the
3655 // outermost MergeMem. The system must, of course, prevent unschedulable
3656 // memory states from arising, so you can be sure that the state Y is somehow
3657 // a precursor to state Y'.
3658 //
3659 //
3660 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
3661 // of each MergeMemNode array are exactly the numerical alias indexes, including
3662 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
3663 // Compile::alias_type (and kin) produce and manage these indexes.
3664 //
3665 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
3666 // (Note that this provides quick access to the top node inside MergeMem methods,
3667 // without the need to reach out via TLS to Compile::current.)
3668 //
3669 // As a consequence of what was just described, a MergeMem that represents a full
3670 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
3671 // containing all alias categories.
3672 //
3673 // MergeMem nodes never (?) have control inputs, so in(0) is NULL.
3674 //
3675 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
3676 // a memory state for the alias type <N>, or else the top node, meaning that
3677 // there is no particular input for that alias type. Note that the length of
3678 // a MergeMem is variable, and may be extended at any time to accommodate new
3679 // memory states at larger alias indexes. When merges grow, they are of course
3680 // filled with "top" in the unused in() positions.
3681 //
3682 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
3683 // (Top was chosen because it works smoothly with passes like GCM.)
3684 //
3685 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
3686 // the type of random VM bits like TLS references.) Since it is always the
3687 // first non-Bot memory slice, some low-level loops use it to initialize an
3688 // index variable: for (i = AliasIdxRaw; i < req(); i++).
3689 //
3690 //
3691 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
3692 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
3693 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
3694 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
3695 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
3696 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
3697 //
3698 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
3699 // really that different from the other memory inputs. An abbreviation called
3700 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
3701 //
3702 //
3703 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
3704 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
3705 // that "emerges though" the base memory will be marked as excluding the alias types
3706 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
3707 //
3708 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
3709 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
3710 //
3711 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
3712 // (It is currently unimplemented.) As you can see, the resulting merge is
3713 // actually a disjoint union of memory states, rather than an overlay.
3714 //
3715
3716 //------------------------------MergeMemNode-----------------------------------
3717 Node* MergeMemNode::make_empty_memory() {
3718 Node* empty_memory = (Node*) Compile::current()->top();
3719 assert(empty_memory->is_top(), "correct sentinel identity");
3720 return empty_memory;
3721 }
3722
3723 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
3724 init_class_id(Class_MergeMem);
3725 // all inputs are nullified in Node::Node(int)
3726 // set_input(0, NULL); // no control input
3727
3728 // Initialize the edges uniformly to top, for starters.
3729 Node* empty_mem = make_empty_memory();
3730 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
3731 init_req(i,empty_mem);
3732 }
3733 assert(empty_memory() == empty_mem, "");
3734
3735 if( new_base != NULL && new_base->is_MergeMem() ) {
3736 MergeMemNode* mdef = new_base->as_MergeMem();
3737 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
3738 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
3739 mms.set_memory(mms.memory2());
3740 }
3741 assert(base_memory() == mdef->base_memory(), "");
3742 } else {
3743 set_base_memory(new_base);
3744 }
3745 }
3746
3747 // Make a new, untransformed MergeMem with the same base as 'mem'.
3748 // If mem is itself a MergeMem, populate the result with the same edges.
3749 MergeMemNode* MergeMemNode::make(Compile* C, Node* mem) {
3750 return new(C, 1+Compile::AliasIdxRaw) MergeMemNode(mem);
3751 }
3752
3753 //------------------------------cmp--------------------------------------------
3754 uint MergeMemNode::hash() const { return NO_HASH; }
3755 uint MergeMemNode::cmp( const Node &n ) const {
3756 return (&n == this); // Always fail except on self
3757 }
3758
3759 //------------------------------Identity---------------------------------------
3760 Node* MergeMemNode::Identity(PhaseTransform *phase) {
3761 // Identity if this merge point does not record any interesting memory
3762 // disambiguations.
3763 Node* base_mem = base_memory();
3764 Node* empty_mem = empty_memory();
3765 if (base_mem != empty_mem) { // Memory path is not dead?
3766 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3767 Node* mem = in(i);
3768 if (mem != empty_mem && mem != base_mem) {
3769 return this; // Many memory splits; no change
3770 }
3771 }
3772 }
3773 return base_mem; // No memory splits; ID on the one true input
3774 }
3775
3776 //------------------------------Ideal------------------------------------------
3777 // This method is invoked recursively on chains of MergeMem nodes
3778 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3779 // Remove chain'd MergeMems
3780 //
3781 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
3782 // relative to the "in(Bot)". Since we are patching both at the same time,
3783 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
3784 // but rewrite each "in(i)" relative to the new "in(Bot)".
3785 Node *progress = NULL;
3786
3787
3788 Node* old_base = base_memory();
3789 Node* empty_mem = empty_memory();
3790 if (old_base == empty_mem)
3791 return NULL; // Dead memory path.
3792
3793 MergeMemNode* old_mbase;
3794 if (old_base != NULL && old_base->is_MergeMem())
3795 old_mbase = old_base->as_MergeMem();
3796 else
3797 old_mbase = NULL;
3798 Node* new_base = old_base;
3799
3800 // simplify stacked MergeMems in base memory
3801 if (old_mbase) new_base = old_mbase->base_memory();
3802
3803 // the base memory might contribute new slices beyond my req()
3804 if (old_mbase) grow_to_match(old_mbase);
3805
3806 // Look carefully at the base node if it is a phi.
3807 PhiNode* phi_base;
3808 if (new_base != NULL && new_base->is_Phi())
3809 phi_base = new_base->as_Phi();
3810 else
3811 phi_base = NULL;
3812
3813 Node* phi_reg = NULL;
3814 uint phi_len = (uint)-1;
3815 if (phi_base != NULL && !phi_base->is_copy()) {
3816 // do not examine phi if degraded to a copy
3817 phi_reg = phi_base->region();
3818 phi_len = phi_base->req();
3819 // see if the phi is unfinished
3820 for (uint i = 1; i < phi_len; i++) {
3821 if (phi_base->in(i) == NULL) {
3822 // incomplete phi; do not look at it yet!
3823 phi_reg = NULL;
3824 phi_len = (uint)-1;
3825 break;
3826 }
3827 }
3828 }
3829
3830 // Note: We do not call verify_sparse on entry, because inputs
3831 // can normalize to the base_memory via subsume_node or similar
3832 // mechanisms. This method repairs that damage.
3833
3834 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
3835
3836 // Look at each slice.
3837 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3838 Node* old_in = in(i);
3839 // calculate the old memory value
3840 Node* old_mem = old_in;
3841 if (old_mem == empty_mem) old_mem = old_base;
3842 assert(old_mem == memory_at(i), "");
3843
3844 // maybe update (reslice) the old memory value
3845
3846 // simplify stacked MergeMems
3847 Node* new_mem = old_mem;
3848 MergeMemNode* old_mmem;
3849 if (old_mem != NULL && old_mem->is_MergeMem())
3850 old_mmem = old_mem->as_MergeMem();
3851 else
3852 old_mmem = NULL;
3853 if (old_mmem == this) {
3854 // This can happen if loops break up and safepoints disappear.
3855 // A merge of BotPtr (default) with a RawPtr memory derived from a
3856 // safepoint can be rewritten to a merge of the same BotPtr with
3857 // the BotPtr phi coming into the loop. If that phi disappears
3858 // also, we can end up with a self-loop of the mergemem.
3859 // In general, if loops degenerate and memory effects disappear,
3860 // a mergemem can be left looking at itself. This simply means
3861 // that the mergemem's default should be used, since there is
3862 // no longer any apparent effect on this slice.
3863 // Note: If a memory slice is a MergeMem cycle, it is unreachable
3864 // from start. Update the input to TOP.
3865 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
3866 }
3867 else if (old_mmem != NULL) {
3868 new_mem = old_mmem->memory_at(i);
3869 }
3870 // else preceding memory was not a MergeMem
3871
3872 // replace equivalent phis (unfortunately, they do not GVN together)
3873 if (new_mem != NULL && new_mem != new_base &&
3874 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) {
3875 if (new_mem->is_Phi()) {
3876 PhiNode* phi_mem = new_mem->as_Phi();
3877 for (uint i = 1; i < phi_len; i++) {
3878 if (phi_base->in(i) != phi_mem->in(i)) {
3879 phi_mem = NULL;
3880 break;
3881 }
3882 }
3883 if (phi_mem != NULL) {
3884 // equivalent phi nodes; revert to the def
3885 new_mem = new_base;
3886 }
3887 }
3888 }
3889
3890 // maybe store down a new value
3891 Node* new_in = new_mem;
3892 if (new_in == new_base) new_in = empty_mem;
3893
3894 if (new_in != old_in) {
3895 // Warning: Do not combine this "if" with the previous "if"
3896 // A memory slice might have be be rewritten even if it is semantically
3897 // unchanged, if the base_memory value has changed.
3898 set_req(i, new_in);
3899 progress = this; // Report progress
3900 }
3901 }
3902
3903 if (new_base != old_base) {
3904 set_req(Compile::AliasIdxBot, new_base);
3905 // Don't use set_base_memory(new_base), because we need to update du.
3906 assert(base_memory() == new_base, "");
3907 progress = this;
3908 }
3909
3910 if( base_memory() == this ) {
3911 // a self cycle indicates this memory path is dead
3912 set_req(Compile::AliasIdxBot, empty_mem);
3913 }
3914
3915 // Resolve external cycles by calling Ideal on a MergeMem base_memory
3916 // Recursion must occur after the self cycle check above
3917 if( base_memory()->is_MergeMem() ) {
3918 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
3919 Node *m = phase->transform(new_mbase); // Rollup any cycles
3920 if( m != NULL && (m->is_top() ||
3921 m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem) ) {
3922 // propagate rollup of dead cycle to self
3923 set_req(Compile::AliasIdxBot, empty_mem);
3924 }
3925 }
3926
3927 if( base_memory() == empty_mem ) {
3928 progress = this;
3929 // Cut inputs during Parse phase only.
3930 // During Optimize phase a dead MergeMem node will be subsumed by Top.
3931 if( !can_reshape ) {
3932 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3933 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
3934 }
3935 }
3936 }
3937
3938 if( !progress && base_memory()->is_Phi() && can_reshape ) {
3939 // Check if PhiNode::Ideal's "Split phis through memory merges"
3940 // transform should be attempted. Look for this->phi->this cycle.
3941 uint merge_width = req();
3942 if (merge_width > Compile::AliasIdxRaw) {
3943 PhiNode* phi = base_memory()->as_Phi();
3944 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
3945 if (phi->in(i) == this) {
3946 phase->is_IterGVN()->_worklist.push(phi);
3947 break;
3948 }
3949 }
3950 }
3951 }
3952
3953 assert(progress || verify_sparse(), "please, no dups of base");
3954 return progress;
3955 }
3956
3957 //-------------------------set_base_memory-------------------------------------
3958 void MergeMemNode::set_base_memory(Node *new_base) {
3959 Node* empty_mem = empty_memory();
3960 set_req(Compile::AliasIdxBot, new_base);
3961 assert(memory_at(req()) == new_base, "must set default memory");
3962 // Clear out other occurrences of new_base:
3963 if (new_base != empty_mem) {
3964 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3965 if (in(i) == new_base) set_req(i, empty_mem);
3966 }
3967 }
3968 }
3969
3970 //------------------------------out_RegMask------------------------------------
3971 const RegMask &MergeMemNode::out_RegMask() const {
3972 return RegMask::Empty;
3973 }
3974
3975 //------------------------------dump_spec--------------------------------------
3976 #ifndef PRODUCT
3977 void MergeMemNode::dump_spec(outputStream *st) const {
3978 st->print(" {");
3979 Node* base_mem = base_memory();
3980 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
3981 Node* mem = memory_at(i);
3982 if (mem == base_mem) { st->print(" -"); continue; }
3983 st->print( " N%d:", mem->_idx );
3984 Compile::current()->get_adr_type(i)->dump_on(st);
3985 }
3986 st->print(" }");
3987 }
3988 #endif // !PRODUCT
3989
3990
3991 #ifdef ASSERT
3992 static bool might_be_same(Node* a, Node* b) {
3993 if (a == b) return true;
3994 if (!(a->is_Phi() || b->is_Phi())) return false;
3995 // phis shift around during optimization
3996 return true; // pretty stupid...
3997 }
3998
3999 // verify a narrow slice (either incoming or outgoing)
4000 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
4001 if (!VerifyAliases) return; // don't bother to verify unless requested
4002 if (is_error_reported()) return; // muzzle asserts when debugging an error
4003 if (Node::in_dump()) return; // muzzle asserts when printing
4004 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
4005 assert(n != NULL, "");
4006 // Elide intervening MergeMem's
4007 while (n->is_MergeMem()) {
4008 n = n->as_MergeMem()->memory_at(alias_idx);
4009 }
4010 Compile* C = Compile::current();
4011 const TypePtr* n_adr_type = n->adr_type();
4012 if (n == m->empty_memory()) {
4013 // Implicit copy of base_memory()
4014 } else if (n_adr_type != TypePtr::BOTTOM) {
4015 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type");
4016 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
4017 } else {
4018 // A few places like make_runtime_call "know" that VM calls are narrow,
4019 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
4020 bool expected_wide_mem = false;
4021 if (n == m->base_memory()) {
4022 expected_wide_mem = true;
4023 } else if (alias_idx == Compile::AliasIdxRaw ||
4024 n == m->memory_at(Compile::AliasIdxRaw)) {
4025 expected_wide_mem = true;
4026 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
4027 // memory can "leak through" calls on channels that
4028 // are write-once. Allow this also.
4029 expected_wide_mem = true;
4030 }
4031 assert(expected_wide_mem, "expected narrow slice replacement");
4032 }
4033 }
4034 #else // !ASSERT
4035 #define verify_memory_slice(m,i,n) (0) // PRODUCT version is no-op
4036 #endif
4037
4038
4039 //-----------------------------memory_at---------------------------------------
4040 Node* MergeMemNode::memory_at(uint alias_idx) const {
4041 assert(alias_idx >= Compile::AliasIdxRaw ||
4042 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0,
4043 "must avoid base_memory and AliasIdxTop");
4044
4045 // Otherwise, it is a narrow slice.
4046 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
4047 Compile *C = Compile::current();
4048 if (is_empty_memory(n)) {
4049 // the array is sparse; empty slots are the "top" node
4050 n = base_memory();
4051 assert(Node::in_dump()
4052 || n == NULL || n->bottom_type() == Type::TOP
4053 || n->adr_type() == NULL // address is TOP
4054 || n->adr_type() == TypePtr::BOTTOM
4055 || n->adr_type() == TypeRawPtr::BOTTOM
4056 || Compile::current()->AliasLevel() == 0,
4057 "must be a wide memory");
4058 // AliasLevel == 0 if we are organizing the memory states manually.
4059 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
4060 } else {
4061 // make sure the stored slice is sane
4062 #ifdef ASSERT
4063 if (is_error_reported() || Node::in_dump()) {
4064 } else if (might_be_same(n, base_memory())) {
4065 // Give it a pass: It is a mostly harmless repetition of the base.
4066 // This can arise normally from node subsumption during optimization.
4067 } else {
4068 verify_memory_slice(this, alias_idx, n);
4069 }
4070 #endif
4071 }
4072 return n;
4073 }
4074
4075 //---------------------------set_memory_at-------------------------------------
4076 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
4077 verify_memory_slice(this, alias_idx, n);
4078 Node* empty_mem = empty_memory();
4079 if (n == base_memory()) n = empty_mem; // collapse default
4080 uint need_req = alias_idx+1;
4081 if (req() < need_req) {
4082 if (n == empty_mem) return; // already the default, so do not grow me
4083 // grow the sparse array
4084 do {
4085 add_req(empty_mem);
4086 } while (req() < need_req);
4087 }
4088 set_req( alias_idx, n );
4089 }
4090
4091
4092
4093 //--------------------------iteration_setup------------------------------------
4094 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
4095 if (other != NULL) {
4096 grow_to_match(other);
4097 // invariant: the finite support of mm2 is within mm->req()
4098 #ifdef ASSERT
4099 for (uint i = req(); i < other->req(); i++) {
4100 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
4101 }
4102 #endif
4103 }
4104 // Replace spurious copies of base_memory by top.
4105 Node* base_mem = base_memory();
4106 if (base_mem != NULL && !base_mem->is_top()) {
4107 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
4108 if (in(i) == base_mem)
4109 set_req(i, empty_memory());
4110 }
4111 }
4112 }
4113
4114 //---------------------------grow_to_match-------------------------------------
4115 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
4116 Node* empty_mem = empty_memory();
4117 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
4118 // look for the finite support of the other memory
4119 for (uint i = other->req(); --i >= req(); ) {
4120 if (other->in(i) != empty_mem) {
4121 uint new_len = i+1;
4122 while (req() < new_len) add_req(empty_mem);
4123 break;
4124 }
4125 }
4126 }
4127
4128 //---------------------------verify_sparse-------------------------------------
4129 #ifndef PRODUCT
4130 bool MergeMemNode::verify_sparse() const {
4131 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
4132 Node* base_mem = base_memory();
4133 // The following can happen in degenerate cases, since empty==top.
4134 if (is_empty_memory(base_mem)) return true;
4135 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4136 assert(in(i) != NULL, "sane slice");
4137 if (in(i) == base_mem) return false; // should have been the sentinel value!
4138 }
4139 return true;
4140 }
4141
4142 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
4143 Node* n;
4144 n = mm->in(idx);
4145 if (mem == n) return true; // might be empty_memory()
4146 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
4147 if (mem == n) return true;
4148 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) {
4149 if (mem == n) return true;
4150 if (n == NULL) break;
4151 }
4152 return false;
4153 }
4154 #endif // !PRODUCT