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 || opc == Op_MemBarAcquireLock)) ||
929 opc == Op_MemBarRelease || opc == Op_MemBarCPUOrder ||
930 opc == Op_MemBarReleaseLock) {
931 Node* mem = current->in(0)->in(TypeFunc::Memory);
932 if (mem->is_MergeMem()) {
933 MergeMemNode* merge = mem->as_MergeMem();
934 Node* new_st = merge->memory_at(alias_idx);
935 if (new_st == merge->base_memory()) {
936 // Keep searching
937 current = merge->base_memory();
938 continue;
939 }
940 // Save the new memory state for the slice and fall through
941 // to exit.
942 result = new_st;
943 }
944 }
945 break;
946 }
947 if (result != NULL) {
948 st = result;
949 }
950 }
951
952
953 // Loop around twice in the case Load -> Initialize -> Store.
954 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
955 for (int trip = 0; trip <= 1; trip++) {
956
957 if (st->is_Store()) {
958 Node* st_adr = st->in(MemNode::Address);
959 if (!phase->eqv(st_adr, ld_adr)) {
960 // Try harder before giving up... Match raw and non-raw pointers.
961 intptr_t st_off = 0;
962 AllocateNode* alloc = AllocateNode::Ideal_allocation(st_adr, phase, st_off);
963 if (alloc == NULL) return NULL;
964 intptr_t ld_off = 0;
965 AllocateNode* allo2 = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
966 if (alloc != allo2) return NULL;
967 if (ld_off != st_off) return NULL;
968 // At this point we have proven something like this setup:
969 // A = Allocate(...)
970 // L = LoadQ(, AddP(CastPP(, A.Parm),, #Off))
971 // S = StoreQ(, AddP(, A.Parm , #Off), V)
972 // (Actually, we haven't yet proven the Q's are the same.)
973 // In other words, we are loading from a casted version of
974 // the same pointer-and-offset that we stored to.
975 // Thus, we are able to replace L by V.
976 }
977 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
978 if (store_Opcode() != st->Opcode())
979 return NULL;
980 return st->in(MemNode::ValueIn);
981 }
982
983 intptr_t offset = 0; // scratch
984
985 // A load from a freshly-created object always returns zero.
986 // (This can happen after LoadNode::Ideal resets the load's memory input
987 // to find_captured_store, which returned InitializeNode::zero_memory.)
988 if (st->is_Proj() && st->in(0)->is_Allocate() &&
989 st->in(0) == AllocateNode::Ideal_allocation(ld_adr, phase, offset) &&
990 offset >= st->in(0)->as_Allocate()->minimum_header_size()) {
991 // return a zero value for the load's basic type
992 // (This is one of the few places where a generic PhaseTransform
993 // can create new nodes. Think of it as lazily manifesting
994 // virtually pre-existing constants.)
995 return phase->zerocon(memory_type());
996 }
997
998 // A load from an initialization barrier can match a captured store.
999 if (st->is_Proj() && st->in(0)->is_Initialize()) {
1000 InitializeNode* init = st->in(0)->as_Initialize();
1001 AllocateNode* alloc = init->allocation();
1002 if (alloc != NULL &&
1003 alloc == AllocateNode::Ideal_allocation(ld_adr, phase, offset)) {
1004 // examine a captured store value
1005 st = init->find_captured_store(offset, memory_size(), phase);
1006 if (st != NULL)
1007 continue; // take one more trip around
1008 }
1009 }
1010
1011 break;
1012 }
1013
1014 return NULL;
1015 }
1016
1017 //----------------------is_instance_field_load_with_local_phi------------------
1018 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
1019 if( in(MemNode::Memory)->is_Phi() && in(MemNode::Memory)->in(0) == ctrl &&
1020 in(MemNode::Address)->is_AddP() ) {
1021 const TypeOopPtr* t_oop = in(MemNode::Address)->bottom_type()->isa_oopptr();
1022 // Only instances.
1023 if( t_oop != NULL && t_oop->is_known_instance_field() &&
1024 t_oop->offset() != Type::OffsetBot &&
1025 t_oop->offset() != Type::OffsetTop) {
1026 return true;
1027 }
1028 }
1029 return false;
1030 }
1031
1032 //------------------------------Identity---------------------------------------
1033 // Loads are identity if previous store is to same address
1034 Node *LoadNode::Identity( PhaseTransform *phase ) {
1035 // If the previous store-maker is the right kind of Store, and the store is
1036 // to the same address, then we are equal to the value stored.
1037 Node* mem = in(MemNode::Memory);
1038 Node* value = can_see_stored_value(mem, phase);
1039 if( value ) {
1040 // byte, short & char stores truncate naturally.
1041 // A load has to load the truncated value which requires
1042 // some sort of masking operation and that requires an
1043 // Ideal call instead of an Identity call.
1044 if (memory_size() < BytesPerInt) {
1045 // If the input to the store does not fit with the load's result type,
1046 // it must be truncated via an Ideal call.
1047 if (!phase->type(value)->higher_equal(phase->type(this)))
1048 return this;
1049 }
1050 // (This works even when value is a Con, but LoadNode::Value
1051 // usually runs first, producing the singleton type of the Con.)
1052 return value;
1053 }
1054
1055 // Search for an existing data phi which was generated before for the same
1056 // instance's field to avoid infinite generation of phis in a loop.
1057 Node *region = mem->in(0);
1058 if (is_instance_field_load_with_local_phi(region)) {
1059 const TypePtr *addr_t = in(MemNode::Address)->bottom_type()->isa_ptr();
1060 int this_index = phase->C->get_alias_index(addr_t);
1061 int this_offset = addr_t->offset();
1062 int this_id = addr_t->is_oopptr()->instance_id();
1063 const Type* this_type = bottom_type();
1064 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1065 Node* phi = region->fast_out(i);
1066 if (phi->is_Phi() && phi != mem &&
1067 phi->as_Phi()->is_same_inst_field(this_type, this_id, this_index, this_offset)) {
1068 return phi;
1069 }
1070 }
1071 }
1072
1073 return this;
1074 }
1075
1076
1077 // Returns true if the AliasType refers to the field that holds the
1078 // cached box array. Currently only handles the IntegerCache case.
1079 static bool is_autobox_cache(Compile::AliasType* atp) {
1080 if (atp != NULL && atp->field() != NULL) {
1081 ciField* field = atp->field();
1082 ciSymbol* klass = field->holder()->name();
1083 if (field->name() == ciSymbol::cache_field_name() &&
1084 field->holder()->uses_default_loader() &&
1085 klass == ciSymbol::java_lang_Integer_IntegerCache()) {
1086 return true;
1087 }
1088 }
1089 return false;
1090 }
1091
1092 // Fetch the base value in the autobox array
1093 static bool fetch_autobox_base(Compile::AliasType* atp, int& cache_offset) {
1094 if (atp != NULL && atp->field() != NULL) {
1095 ciField* field = atp->field();
1096 ciSymbol* klass = field->holder()->name();
1097 if (field->name() == ciSymbol::cache_field_name() &&
1098 field->holder()->uses_default_loader() &&
1099 klass == ciSymbol::java_lang_Integer_IntegerCache()) {
1100 assert(field->is_constant(), "what?");
1101 ciObjArray* array = field->constant_value().as_object()->as_obj_array();
1102 // Fetch the box object at the base of the array and get its value
1103 ciInstance* box = array->obj_at(0)->as_instance();
1104 ciInstanceKlass* ik = box->klass()->as_instance_klass();
1105 if (ik->nof_nonstatic_fields() == 1) {
1106 // This should be true nonstatic_field_at requires calling
1107 // nof_nonstatic_fields so check it anyway
1108 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1109 cache_offset = c.as_int();
1110 }
1111 return true;
1112 }
1113 }
1114 return false;
1115 }
1116
1117 // Returns true if the AliasType refers to the value field of an
1118 // autobox object. Currently only handles Integer.
1119 static bool is_autobox_object(Compile::AliasType* atp) {
1120 if (atp != NULL && atp->field() != NULL) {
1121 ciField* field = atp->field();
1122 ciSymbol* klass = field->holder()->name();
1123 if (field->name() == ciSymbol::value_name() &&
1124 field->holder()->uses_default_loader() &&
1125 klass == ciSymbol::java_lang_Integer()) {
1126 return true;
1127 }
1128 }
1129 return false;
1130 }
1131
1132
1133 // We're loading from an object which has autobox behaviour.
1134 // If this object is result of a valueOf call we'll have a phi
1135 // merging a newly allocated object and a load from the cache.
1136 // We want to replace this load with the original incoming
1137 // argument to the valueOf call.
1138 Node* LoadNode::eliminate_autobox(PhaseGVN* phase) {
1139 Node* base = in(Address)->in(AddPNode::Base);
1140 if (base->is_Phi() && base->req() == 3) {
1141 AllocateNode* allocation = NULL;
1142 int allocation_index = -1;
1143 int load_index = -1;
1144 for (uint i = 1; i < base->req(); i++) {
1145 allocation = AllocateNode::Ideal_allocation(base->in(i), phase);
1146 if (allocation != NULL) {
1147 allocation_index = i;
1148 load_index = 3 - allocation_index;
1149 break;
1150 }
1151 }
1152 bool has_load = ( allocation != NULL &&
1153 (base->in(load_index)->is_Load() ||
1154 base->in(load_index)->is_DecodeN() &&
1155 base->in(load_index)->in(1)->is_Load()) );
1156 if (has_load && in(Memory)->is_Phi() && in(Memory)->in(0) == base->in(0)) {
1157 // Push the loads from the phi that comes from valueOf up
1158 // through it to allow elimination of the loads and the recovery
1159 // of the original value.
1160 Node* mem_phi = in(Memory);
1161 Node* offset = in(Address)->in(AddPNode::Offset);
1162 Node* region = base->in(0);
1163
1164 Node* in1 = clone();
1165 Node* in1_addr = in1->in(Address)->clone();
1166 in1_addr->set_req(AddPNode::Base, base->in(allocation_index));
1167 in1_addr->set_req(AddPNode::Address, base->in(allocation_index));
1168 in1_addr->set_req(AddPNode::Offset, offset);
1169 in1->set_req(0, region->in(allocation_index));
1170 in1->set_req(Address, in1_addr);
1171 in1->set_req(Memory, mem_phi->in(allocation_index));
1172
1173 Node* in2 = clone();
1174 Node* in2_addr = in2->in(Address)->clone();
1175 in2_addr->set_req(AddPNode::Base, base->in(load_index));
1176 in2_addr->set_req(AddPNode::Address, base->in(load_index));
1177 in2_addr->set_req(AddPNode::Offset, offset);
1178 in2->set_req(0, region->in(load_index));
1179 in2->set_req(Address, in2_addr);
1180 in2->set_req(Memory, mem_phi->in(load_index));
1181
1182 in1_addr = phase->transform(in1_addr);
1183 in1 = phase->transform(in1);
1184 in2_addr = phase->transform(in2_addr);
1185 in2 = phase->transform(in2);
1186
1187 PhiNode* result = PhiNode::make_blank(region, this);
1188 result->set_req(allocation_index, in1);
1189 result->set_req(load_index, in2);
1190 return result;
1191 }
1192 } else if (base->is_Load() ||
1193 base->is_DecodeN() && base->in(1)->is_Load()) {
1194 if (base->is_DecodeN()) {
1195 // Get LoadN node which loads cached Integer object
1196 base = base->in(1);
1197 }
1198 // Eliminate the load of Integer.value for integers from the cache
1199 // array by deriving the value from the index into the array.
1200 // Capture the offset of the load and then reverse the computation.
1201 Node* load_base = base->in(Address)->in(AddPNode::Base);
1202 if (load_base->is_DecodeN()) {
1203 // Get LoadN node which loads IntegerCache.cache field
1204 load_base = load_base->in(1);
1205 }
1206 if (load_base != NULL) {
1207 Compile::AliasType* atp = phase->C->alias_type(load_base->adr_type());
1208 intptr_t cache_offset;
1209 int shift = -1;
1210 Node* cache = NULL;
1211 if (is_autobox_cache(atp)) {
1212 shift = exact_log2(type2aelembytes(T_OBJECT));
1213 cache = AddPNode::Ideal_base_and_offset(load_base->in(Address), phase, cache_offset);
1214 }
1215 if (cache != NULL && base->in(Address)->is_AddP()) {
1216 Node* elements[4];
1217 int count = base->in(Address)->as_AddP()->unpack_offsets(elements, ARRAY_SIZE(elements));
1218 int cache_low;
1219 if (count > 0 && fetch_autobox_base(atp, cache_low)) {
1220 int offset = arrayOopDesc::base_offset_in_bytes(memory_type()) - (cache_low << shift);
1221 // Add up all the offsets making of the address of the load
1222 Node* result = elements[0];
1223 for (int i = 1; i < count; i++) {
1224 result = phase->transform(new (phase->C, 3) AddXNode(result, elements[i]));
1225 }
1226 // Remove the constant offset from the address and then
1227 // remove the scaling of the offset to recover the original index.
1228 result = phase->transform(new (phase->C, 3) AddXNode(result, phase->MakeConX(-offset)));
1229 if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) {
1230 // Peel the shift off directly but wrap it in a dummy node
1231 // since Ideal can't return existing nodes
1232 result = new (phase->C, 3) RShiftXNode(result->in(1), phase->intcon(0));
1233 } else {
1234 result = new (phase->C, 3) RShiftXNode(result, phase->intcon(shift));
1235 }
1236 #ifdef _LP64
1237 result = new (phase->C, 2) ConvL2INode(phase->transform(result));
1238 #endif
1239 return result;
1240 }
1241 }
1242 }
1243 }
1244 return NULL;
1245 }
1246
1247 //------------------------------split_through_phi------------------------------
1248 // Split instance field load through Phi.
1249 Node *LoadNode::split_through_phi(PhaseGVN *phase) {
1250 Node* mem = in(MemNode::Memory);
1251 Node* address = in(MemNode::Address);
1252 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1253 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1254
1255 assert(mem->is_Phi() && (t_oop != NULL) &&
1256 t_oop->is_known_instance_field(), "invalide conditions");
1257
1258 Node *region = mem->in(0);
1259 if (region == NULL) {
1260 return NULL; // Wait stable graph
1261 }
1262 uint cnt = mem->req();
1263 for (uint i = 1; i < cnt; i++) {
1264 Node* rc = region->in(i);
1265 if (rc == NULL || phase->type(rc) == Type::TOP)
1266 return NULL; // Wait stable graph
1267 Node *in = mem->in(i);
1268 if (in == NULL) {
1269 return NULL; // Wait stable graph
1270 }
1271 }
1272 // Check for loop invariant.
1273 if (cnt == 3) {
1274 for (uint i = 1; i < cnt; i++) {
1275 Node *in = mem->in(i);
1276 Node* m = MemNode::optimize_memory_chain(in, addr_t, phase);
1277 if (m == mem) {
1278 set_req(MemNode::Memory, mem->in(cnt - i)); // Skip this phi.
1279 return this;
1280 }
1281 }
1282 }
1283 // Split through Phi (see original code in loopopts.cpp).
1284 assert(phase->C->have_alias_type(addr_t), "instance should have alias type");
1285
1286 // Do nothing here if Identity will find a value
1287 // (to avoid infinite chain of value phis generation).
1288 if (!phase->eqv(this, this->Identity(phase)))
1289 return NULL;
1290
1291 // Skip the split if the region dominates some control edge of the address.
1292 if (!MemNode::all_controls_dominate(address, region))
1293 return NULL;
1294
1295 const Type* this_type = this->bottom_type();
1296 int this_index = phase->C->get_alias_index(addr_t);
1297 int this_offset = addr_t->offset();
1298 int this_iid = addr_t->is_oopptr()->instance_id();
1299 PhaseIterGVN *igvn = phase->is_IterGVN();
1300 Node *phi = new (igvn->C, region->req()) PhiNode(region, this_type, NULL, this_iid, this_index, this_offset);
1301 for (uint i = 1; i < region->req(); i++) {
1302 Node *x;
1303 Node* the_clone = NULL;
1304 if (region->in(i) == phase->C->top()) {
1305 x = phase->C->top(); // Dead path? Use a dead data op
1306 } else {
1307 x = this->clone(); // Else clone up the data op
1308 the_clone = x; // Remember for possible deletion.
1309 // Alter data node to use pre-phi inputs
1310 if (this->in(0) == region) {
1311 x->set_req(0, region->in(i));
1312 } else {
1313 x->set_req(0, NULL);
1314 }
1315 for (uint j = 1; j < this->req(); j++) {
1316 Node *in = this->in(j);
1317 if (in->is_Phi() && in->in(0) == region)
1318 x->set_req(j, in->in(i)); // Use pre-Phi input for the clone
1319 }
1320 }
1321 // Check for a 'win' on some paths
1322 const Type *t = x->Value(igvn);
1323
1324 bool singleton = t->singleton();
1325
1326 // See comments in PhaseIdealLoop::split_thru_phi().
1327 if (singleton && t == Type::TOP) {
1328 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1329 }
1330
1331 if (singleton) {
1332 x = igvn->makecon(t);
1333 } else {
1334 // We now call Identity to try to simplify the cloned node.
1335 // Note that some Identity methods call phase->type(this).
1336 // Make sure that the type array is big enough for
1337 // our new node, even though we may throw the node away.
1338 // (This tweaking with igvn only works because x is a new node.)
1339 igvn->set_type(x, t);
1340 // If x is a TypeNode, capture any more-precise type permanently into Node
1341 // otherwise it will be not updated during igvn->transform since
1342 // igvn->type(x) is set to x->Value() already.
1343 x->raise_bottom_type(t);
1344 Node *y = x->Identity(igvn);
1345 if (y != x) {
1346 x = y;
1347 } else {
1348 y = igvn->hash_find(x);
1349 if (y) {
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 // Record Phi
1364 igvn->register_new_node_with_optimizer(phi);
1365 return phi;
1366 }
1367
1368 //------------------------------Ideal------------------------------------------
1369 // If the load is from Field memory and the pointer is non-null, we can
1370 // zero out the control input.
1371 // If the offset is constant and the base is an object allocation,
1372 // try to hook me up to the exact initializing store.
1373 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1374 Node* p = MemNode::Ideal_common(phase, can_reshape);
1375 if (p) return (p == NodeSentinel) ? NULL : p;
1376
1377 Node* ctrl = in(MemNode::Control);
1378 Node* address = in(MemNode::Address);
1379
1380 // Skip up past a SafePoint control. Cannot do this for Stores because
1381 // pointer stores & cardmarks must stay on the same side of a SafePoint.
1382 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint &&
1383 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw ) {
1384 ctrl = ctrl->in(0);
1385 set_req(MemNode::Control,ctrl);
1386 }
1387
1388 intptr_t ignore = 0;
1389 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1390 if (base != NULL
1391 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
1392 // Check for useless control edge in some common special cases
1393 if (in(MemNode::Control) != NULL
1394 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1395 && all_controls_dominate(base, phase->C->start())) {
1396 // A method-invariant, non-null address (constant or 'this' argument).
1397 set_req(MemNode::Control, NULL);
1398 }
1399
1400 if (EliminateAutoBox && can_reshape) {
1401 assert(!phase->type(base)->higher_equal(TypePtr::NULL_PTR), "the autobox pointer should be non-null");
1402 Compile::AliasType* atp = phase->C->alias_type(adr_type());
1403 if (is_autobox_object(atp)) {
1404 Node* result = eliminate_autobox(phase);
1405 if (result != NULL) return result;
1406 }
1407 }
1408 }
1409
1410 Node* mem = in(MemNode::Memory);
1411 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1412
1413 if (addr_t != NULL) {
1414 // try to optimize our memory input
1415 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, phase);
1416 if (opt_mem != mem) {
1417 set_req(MemNode::Memory, opt_mem);
1418 if (phase->type( opt_mem ) == Type::TOP) return NULL;
1419 return this;
1420 }
1421 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1422 if (can_reshape && opt_mem->is_Phi() &&
1423 (t_oop != NULL) && t_oop->is_known_instance_field()) {
1424 // Split instance field load through Phi.
1425 Node* result = split_through_phi(phase);
1426 if (result != NULL) return result;
1427 }
1428 }
1429
1430 // Check for prior store with a different base or offset; make Load
1431 // independent. Skip through any number of them. Bail out if the stores
1432 // are in an endless dead cycle and report no progress. This is a key
1433 // transform for Reflection. However, if after skipping through the Stores
1434 // we can't then fold up against a prior store do NOT do the transform as
1435 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
1436 // array memory alive twice: once for the hoisted Load and again after the
1437 // bypassed Store. This situation only works if EVERYBODY who does
1438 // anti-dependence work knows how to bypass. I.e. we need all
1439 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
1440 // the alias index stuff. So instead, peek through Stores and IFF we can
1441 // fold up, do so.
1442 Node* prev_mem = find_previous_store(phase);
1443 // Steps (a), (b): Walk past independent stores to find an exact match.
1444 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) {
1445 // (c) See if we can fold up on the spot, but don't fold up here.
1446 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
1447 // just return a prior value, which is done by Identity calls.
1448 if (can_see_stored_value(prev_mem, phase)) {
1449 // Make ready for step (d):
1450 set_req(MemNode::Memory, prev_mem);
1451 return this;
1452 }
1453 }
1454
1455 return NULL; // No further progress
1456 }
1457
1458 // Helper to recognize certain Klass fields which are invariant across
1459 // some group of array types (e.g., int[] or all T[] where T < Object).
1460 const Type*
1461 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1462 ciKlass* klass) const {
1463 if (tkls->offset() == Klass::modifier_flags_offset_in_bytes() + (int)sizeof(oopDesc)) {
1464 // The field is Klass::_modifier_flags. Return its (constant) value.
1465 // (Folds up the 2nd indirection in aClassConstant.getModifiers().)
1466 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags");
1467 return TypeInt::make(klass->modifier_flags());
1468 }
1469 if (tkls->offset() == Klass::access_flags_offset_in_bytes() + (int)sizeof(oopDesc)) {
1470 // The field is Klass::_access_flags. Return its (constant) value.
1471 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1472 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags");
1473 return TypeInt::make(klass->access_flags());
1474 }
1475 if (tkls->offset() == Klass::layout_helper_offset_in_bytes() + (int)sizeof(oopDesc)) {
1476 // The field is Klass::_layout_helper. Return its constant value if known.
1477 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper");
1478 return TypeInt::make(klass->layout_helper());
1479 }
1480
1481 // No match.
1482 return NULL;
1483 }
1484
1485 //------------------------------Value-----------------------------------------
1486 const Type *LoadNode::Value( PhaseTransform *phase ) const {
1487 // Either input is TOP ==> the result is TOP
1488 Node* mem = in(MemNode::Memory);
1489 const Type *t1 = phase->type(mem);
1490 if (t1 == Type::TOP) return Type::TOP;
1491 Node* adr = in(MemNode::Address);
1492 const TypePtr* tp = phase->type(adr)->isa_ptr();
1493 if (tp == NULL || tp->empty()) return Type::TOP;
1494 int off = tp->offset();
1495 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
1496 Compile* C = phase->C;
1497
1498 // Try to guess loaded type from pointer type
1499 if (tp->base() == Type::AryPtr) {
1500 const Type *t = tp->is_aryptr()->elem();
1501 // Don't do this for integer types. There is only potential profit if
1502 // the element type t is lower than _type; that is, for int types, if _type is
1503 // more restrictive than t. This only happens here if one is short and the other
1504 // char (both 16 bits), and in those cases we've made an intentional decision
1505 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
1506 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
1507 //
1508 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
1509 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
1510 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
1511 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
1512 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
1513 // In fact, that could have been the original type of p1, and p1 could have
1514 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
1515 // expression (LShiftL quux 3) independently optimized to the constant 8.
1516 if ((t->isa_int() == NULL) && (t->isa_long() == NULL)
1517 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
1518 // t might actually be lower than _type, if _type is a unique
1519 // concrete subclass of abstract class t.
1520 // Make sure the reference is not into the header, by comparing
1521 // the offset against the offset of the start of the array's data.
1522 // Different array types begin at slightly different offsets (12 vs. 16).
1523 // We choose T_BYTE as an example base type that is least restrictive
1524 // as to alignment, which will therefore produce the smallest
1525 // possible base offset.
1526 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
1527 if ((uint)off >= (uint)min_base_off) { // is the offset beyond the header?
1528 const Type* jt = t->join(_type);
1529 // In any case, do not allow the join, per se, to empty out the type.
1530 if (jt->empty() && !t->empty()) {
1531 // This can happen if a interface-typed array narrows to a class type.
1532 jt = _type;
1533 }
1534
1535 if (EliminateAutoBox && adr->is_AddP()) {
1536 // The pointers in the autobox arrays are always non-null
1537 Node* base = adr->in(AddPNode::Base);
1538 if (base != NULL &&
1539 !phase->type(base)->higher_equal(TypePtr::NULL_PTR)) {
1540 Compile::AliasType* atp = C->alias_type(base->adr_type());
1541 if (is_autobox_cache(atp)) {
1542 return jt->join(TypePtr::NOTNULL)->is_ptr();
1543 }
1544 }
1545 }
1546 return jt;
1547 }
1548 }
1549 } else if (tp->base() == Type::InstPtr) {
1550 ciEnv* env = C->env();
1551 const TypeInstPtr* tinst = tp->is_instptr();
1552 ciKlass* klass = tinst->klass();
1553 assert( off != Type::OffsetBot ||
1554 // arrays can be cast to Objects
1555 tp->is_oopptr()->klass()->is_java_lang_Object() ||
1556 // unsafe field access may not have a constant offset
1557 C->has_unsafe_access(),
1558 "Field accesses must be precise" );
1559 // For oop loads, we expect the _type to be precise
1560 if (klass == env->String_klass() &&
1561 adr->is_AddP() && off != Type::OffsetBot) {
1562 // For constant Strings treat the final fields as compile time constants.
1563 Node* base = adr->in(AddPNode::Base);
1564 const TypeOopPtr* t = phase->type(base)->isa_oopptr();
1565 if (t != NULL && t->singleton()) {
1566 ciField* field = env->String_klass()->get_field_by_offset(off, false);
1567 if (field != NULL && field->is_final()) {
1568 ciObject* string = t->const_oop();
1569 ciConstant constant = string->as_instance()->field_value(field);
1570 if (constant.basic_type() == T_INT) {
1571 return TypeInt::make(constant.as_int());
1572 } else if (constant.basic_type() == T_ARRAY) {
1573 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
1574 return TypeNarrowOop::make_from_constant(constant.as_object(), true);
1575 } else {
1576 return TypeOopPtr::make_from_constant(constant.as_object(), true);
1577 }
1578 }
1579 }
1580 }
1581 }
1582 // Optimizations for constant objects
1583 ciObject* const_oop = tinst->const_oop();
1584 if (const_oop != NULL) {
1585 // For constant CallSites treat the target field as a compile time constant.
1586 if (const_oop->is_call_site()) {
1587 ciCallSite* call_site = const_oop->as_call_site();
1588 ciField* field = call_site->klass()->as_instance_klass()->get_field_by_offset(off, /*is_static=*/ false);
1589 if (field != NULL && field->is_call_site_target()) {
1590 ciMethodHandle* target = call_site->get_target();
1591 if (target != NULL) { // just in case
1592 ciConstant constant(T_OBJECT, target);
1593 const Type* t;
1594 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
1595 t = TypeNarrowOop::make_from_constant(constant.as_object(), true);
1596 } else {
1597 t = TypeOopPtr::make_from_constant(constant.as_object(), true);
1598 }
1599 // Add a dependence for invalidation of the optimization.
1600 if (!call_site->is_constant_call_site()) {
1601 C->dependencies()->assert_call_site_target_value(call_site, target);
1602 }
1603 return t;
1604 }
1605 }
1606 }
1607 }
1608 } else if (tp->base() == Type::KlassPtr) {
1609 assert( off != Type::OffsetBot ||
1610 // arrays can be cast to Objects
1611 tp->is_klassptr()->klass()->is_java_lang_Object() ||
1612 // also allow array-loading from the primary supertype
1613 // array during subtype checks
1614 Opcode() == Op_LoadKlass,
1615 "Field accesses must be precise" );
1616 // For klass/static loads, we expect the _type to be precise
1617 }
1618
1619 const TypeKlassPtr *tkls = tp->isa_klassptr();
1620 if (tkls != NULL && !StressReflectiveCode) {
1621 ciKlass* klass = tkls->klass();
1622 if (klass->is_loaded() && tkls->klass_is_exact()) {
1623 // We are loading a field from a Klass metaobject whose identity
1624 // is known at compile time (the type is "exact" or "precise").
1625 // Check for fields we know are maintained as constants by the VM.
1626 if (tkls->offset() == Klass::super_check_offset_offset_in_bytes() + (int)sizeof(oopDesc)) {
1627 // The field is Klass::_super_check_offset. Return its (constant) value.
1628 // (Folds up type checking code.)
1629 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
1630 return TypeInt::make(klass->super_check_offset());
1631 }
1632 // Compute index into primary_supers array
1633 juint depth = (tkls->offset() - (Klass::primary_supers_offset_in_bytes() + (int)sizeof(oopDesc))) / sizeof(klassOop);
1634 // Check for overflowing; use unsigned compare to handle the negative case.
1635 if( depth < ciKlass::primary_super_limit() ) {
1636 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1637 // (Folds up type checking code.)
1638 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1639 ciKlass *ss = klass->super_of_depth(depth);
1640 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1641 }
1642 const Type* aift = load_array_final_field(tkls, klass);
1643 if (aift != NULL) return aift;
1644 if (tkls->offset() == in_bytes(arrayKlass::component_mirror_offset()) + (int)sizeof(oopDesc)
1645 && klass->is_array_klass()) {
1646 // The field is arrayKlass::_component_mirror. Return its (constant) value.
1647 // (Folds up aClassConstant.getComponentType, common in Arrays.copyOf.)
1648 assert(Opcode() == Op_LoadP, "must load an oop from _component_mirror");
1649 return TypeInstPtr::make(klass->as_array_klass()->component_mirror());
1650 }
1651 if (tkls->offset() == Klass::java_mirror_offset_in_bytes() + (int)sizeof(oopDesc)) {
1652 // The field is Klass::_java_mirror. Return its (constant) value.
1653 // (Folds up the 2nd indirection in anObjConstant.getClass().)
1654 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
1655 return TypeInstPtr::make(klass->java_mirror());
1656 }
1657 }
1658
1659 // We can still check if we are loading from the primary_supers array at a
1660 // shallow enough depth. Even though the klass is not exact, entries less
1661 // than or equal to its super depth are correct.
1662 if (klass->is_loaded() ) {
1663 ciType *inner = klass->klass();
1664 while( inner->is_obj_array_klass() )
1665 inner = inner->as_obj_array_klass()->base_element_type();
1666 if( inner->is_instance_klass() &&
1667 !inner->as_instance_klass()->flags().is_interface() ) {
1668 // Compute index into primary_supers array
1669 juint depth = (tkls->offset() - (Klass::primary_supers_offset_in_bytes() + (int)sizeof(oopDesc))) / sizeof(klassOop);
1670 // Check for overflowing; use unsigned compare to handle the negative case.
1671 if( depth < ciKlass::primary_super_limit() &&
1672 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case
1673 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1674 // (Folds up type checking code.)
1675 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1676 ciKlass *ss = klass->super_of_depth(depth);
1677 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1678 }
1679 }
1680 }
1681
1682 // If the type is enough to determine that the thing is not an array,
1683 // we can give the layout_helper a positive interval type.
1684 // This will help short-circuit some reflective code.
1685 if (tkls->offset() == Klass::layout_helper_offset_in_bytes() + (int)sizeof(oopDesc)
1686 && !klass->is_array_klass() // not directly typed as an array
1687 && !klass->is_interface() // specifically not Serializable & Cloneable
1688 && !klass->is_java_lang_Object() // not the supertype of all T[]
1689 ) {
1690 // Note: When interfaces are reliable, we can narrow the interface
1691 // test to (klass != Serializable && klass != Cloneable).
1692 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
1693 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
1694 // The key property of this type is that it folds up tests
1695 // for array-ness, since it proves that the layout_helper is positive.
1696 // Thus, a generic value like the basic object layout helper works fine.
1697 return TypeInt::make(min_size, max_jint, Type::WidenMin);
1698 }
1699 }
1700
1701 // If we are loading from a freshly-allocated object, produce a zero,
1702 // if the load is provably beyond the header of the object.
1703 // (Also allow a variable load from a fresh array to produce zero.)
1704 const TypeOopPtr *tinst = tp->isa_oopptr();
1705 bool is_instance = (tinst != NULL) && tinst->is_known_instance_field();
1706 if (ReduceFieldZeroing || is_instance) {
1707 Node* value = can_see_stored_value(mem,phase);
1708 if (value != NULL && value->is_Con())
1709 return value->bottom_type();
1710 }
1711
1712 if (is_instance) {
1713 // If we have an instance type and our memory input is the
1714 // programs's initial memory state, there is no matching store,
1715 // so just return a zero of the appropriate type
1716 Node *mem = in(MemNode::Memory);
1717 if (mem->is_Parm() && mem->in(0)->is_Start()) {
1718 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
1719 return Type::get_zero_type(_type->basic_type());
1720 }
1721 }
1722 return _type;
1723 }
1724
1725 //------------------------------match_edge-------------------------------------
1726 // Do we Match on this edge index or not? Match only the address.
1727 uint LoadNode::match_edge(uint idx) const {
1728 return idx == MemNode::Address;
1729 }
1730
1731 //--------------------------LoadBNode::Ideal--------------------------------------
1732 //
1733 // If the previous store is to the same address as this load,
1734 // and the value stored was larger than a byte, replace this load
1735 // with the value stored truncated to a byte. If no truncation is
1736 // needed, the replacement is done in LoadNode::Identity().
1737 //
1738 Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1739 Node* mem = in(MemNode::Memory);
1740 Node* value = can_see_stored_value(mem,phase);
1741 if( value && !phase->type(value)->higher_equal( _type ) ) {
1742 Node *result = phase->transform( new (phase->C, 3) LShiftINode(value, phase->intcon(24)) );
1743 return new (phase->C, 3) RShiftINode(result, phase->intcon(24));
1744 }
1745 // Identity call will handle the case where truncation is not needed.
1746 return LoadNode::Ideal(phase, can_reshape);
1747 }
1748
1749 //--------------------------LoadUBNode::Ideal-------------------------------------
1750 //
1751 // If the previous store is to the same address as this load,
1752 // and the value stored was larger than a byte, replace this load
1753 // with the value stored truncated to a byte. If no truncation is
1754 // needed, the replacement is done in LoadNode::Identity().
1755 //
1756 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
1757 Node* mem = in(MemNode::Memory);
1758 Node* value = can_see_stored_value(mem, phase);
1759 if (value && !phase->type(value)->higher_equal(_type))
1760 return new (phase->C, 3) AndINode(value, phase->intcon(0xFF));
1761 // Identity call will handle the case where truncation is not needed.
1762 return LoadNode::Ideal(phase, can_reshape);
1763 }
1764
1765 //--------------------------LoadUSNode::Ideal-------------------------------------
1766 //
1767 // If the previous store is to the same address as this load,
1768 // and the value stored was larger than a char, replace this load
1769 // with the value stored truncated to a char. If no truncation is
1770 // needed, the replacement is done in LoadNode::Identity().
1771 //
1772 Node *LoadUSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1773 Node* mem = in(MemNode::Memory);
1774 Node* value = can_see_stored_value(mem,phase);
1775 if( value && !phase->type(value)->higher_equal( _type ) )
1776 return new (phase->C, 3) AndINode(value,phase->intcon(0xFFFF));
1777 // Identity call will handle the case where truncation is not needed.
1778 return LoadNode::Ideal(phase, can_reshape);
1779 }
1780
1781 //--------------------------LoadSNode::Ideal--------------------------------------
1782 //
1783 // If the previous store is to the same address as this load,
1784 // and the value stored was larger than a short, replace this load
1785 // with the value stored truncated to a short. If no truncation is
1786 // needed, the replacement is done in LoadNode::Identity().
1787 //
1788 Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1789 Node* mem = in(MemNode::Memory);
1790 Node* value = can_see_stored_value(mem,phase);
1791 if( value && !phase->type(value)->higher_equal( _type ) ) {
1792 Node *result = phase->transform( new (phase->C, 3) LShiftINode(value, phase->intcon(16)) );
1793 return new (phase->C, 3) RShiftINode(result, phase->intcon(16));
1794 }
1795 // Identity call will handle the case where truncation is not needed.
1796 return LoadNode::Ideal(phase, can_reshape);
1797 }
1798
1799 //=============================================================================
1800 //----------------------------LoadKlassNode::make------------------------------
1801 // Polymorphic factory method:
1802 Node *LoadKlassNode::make( PhaseGVN& gvn, Node *mem, Node *adr, const TypePtr* at, const TypeKlassPtr *tk ) {
1803 Compile* C = gvn.C;
1804 Node *ctl = NULL;
1805 // sanity check the alias category against the created node type
1806 const TypeOopPtr *adr_type = adr->bottom_type()->isa_oopptr();
1807 assert(adr_type != NULL, "expecting TypeOopPtr");
1808 #ifdef _LP64
1809 if (adr_type->is_ptr_to_narrowoop()) {
1810 Node* load_klass = gvn.transform(new (C, 3) LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowoop()));
1811 return new (C, 2) DecodeNNode(load_klass, load_klass->bottom_type()->make_ptr());
1812 }
1813 #endif
1814 assert(!adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
1815 return new (C, 3) LoadKlassNode(ctl, mem, adr, at, tk);
1816 }
1817
1818 //------------------------------Value------------------------------------------
1819 const Type *LoadKlassNode::Value( PhaseTransform *phase ) const {
1820 return klass_value_common(phase);
1821 }
1822
1823 const Type *LoadNode::klass_value_common( PhaseTransform *phase ) const {
1824 // Either input is TOP ==> the result is TOP
1825 const Type *t1 = phase->type( in(MemNode::Memory) );
1826 if (t1 == Type::TOP) return Type::TOP;
1827 Node *adr = in(MemNode::Address);
1828 const Type *t2 = phase->type( adr );
1829 if (t2 == Type::TOP) return Type::TOP;
1830 const TypePtr *tp = t2->is_ptr();
1831 if (TypePtr::above_centerline(tp->ptr()) ||
1832 tp->ptr() == TypePtr::Null) return Type::TOP;
1833
1834 // Return a more precise klass, if possible
1835 const TypeInstPtr *tinst = tp->isa_instptr();
1836 if (tinst != NULL) {
1837 ciInstanceKlass* ik = tinst->klass()->as_instance_klass();
1838 int offset = tinst->offset();
1839 if (ik == phase->C->env()->Class_klass()
1840 && (offset == java_lang_Class::klass_offset_in_bytes() ||
1841 offset == java_lang_Class::array_klass_offset_in_bytes())) {
1842 // We are loading a special hidden field from a Class mirror object,
1843 // the field which points to the VM's Klass metaobject.
1844 ciType* t = tinst->java_mirror_type();
1845 // java_mirror_type returns non-null for compile-time Class constants.
1846 if (t != NULL) {
1847 // constant oop => constant klass
1848 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
1849 return TypeKlassPtr::make(ciArrayKlass::make(t));
1850 }
1851 if (!t->is_klass()) {
1852 // a primitive Class (e.g., int.class) has NULL for a klass field
1853 return TypePtr::NULL_PTR;
1854 }
1855 // (Folds up the 1st indirection in aClassConstant.getModifiers().)
1856 return TypeKlassPtr::make(t->as_klass());
1857 }
1858 // non-constant mirror, so we can't tell what's going on
1859 }
1860 if( !ik->is_loaded() )
1861 return _type; // Bail out if not loaded
1862 if (offset == oopDesc::klass_offset_in_bytes()) {
1863 if (tinst->klass_is_exact()) {
1864 return TypeKlassPtr::make(ik);
1865 }
1866 // See if we can become precise: no subklasses and no interface
1867 // (Note: We need to support verified interfaces.)
1868 if (!ik->is_interface() && !ik->has_subklass()) {
1869 //assert(!UseExactTypes, "this code should be useless with exact types");
1870 // Add a dependence; if any subclass added we need to recompile
1871 if (!ik->is_final()) {
1872 // %%% should use stronger assert_unique_concrete_subtype instead
1873 phase->C->dependencies()->assert_leaf_type(ik);
1874 }
1875 // Return precise klass
1876 return TypeKlassPtr::make(ik);
1877 }
1878
1879 // Return root of possible klass
1880 return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/);
1881 }
1882 }
1883
1884 // Check for loading klass from an array
1885 const TypeAryPtr *tary = tp->isa_aryptr();
1886 if( tary != NULL ) {
1887 ciKlass *tary_klass = tary->klass();
1888 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP
1889 && tary->offset() == oopDesc::klass_offset_in_bytes()) {
1890 if (tary->klass_is_exact()) {
1891 return TypeKlassPtr::make(tary_klass);
1892 }
1893 ciArrayKlass *ak = tary->klass()->as_array_klass();
1894 // If the klass is an object array, we defer the question to the
1895 // array component klass.
1896 if( ak->is_obj_array_klass() ) {
1897 assert( ak->is_loaded(), "" );
1898 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass();
1899 if( base_k->is_loaded() && base_k->is_instance_klass() ) {
1900 ciInstanceKlass* ik = base_k->as_instance_klass();
1901 // See if we can become precise: no subklasses and no interface
1902 if (!ik->is_interface() && !ik->has_subklass()) {
1903 //assert(!UseExactTypes, "this code should be useless with exact types");
1904 // Add a dependence; if any subclass added we need to recompile
1905 if (!ik->is_final()) {
1906 phase->C->dependencies()->assert_leaf_type(ik);
1907 }
1908 // Return precise array klass
1909 return TypeKlassPtr::make(ak);
1910 }
1911 }
1912 return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/);
1913 } else { // Found a type-array?
1914 //assert(!UseExactTypes, "this code should be useless with exact types");
1915 assert( ak->is_type_array_klass(), "" );
1916 return TypeKlassPtr::make(ak); // These are always precise
1917 }
1918 }
1919 }
1920
1921 // Check for loading klass from an array klass
1922 const TypeKlassPtr *tkls = tp->isa_klassptr();
1923 if (tkls != NULL && !StressReflectiveCode) {
1924 ciKlass* klass = tkls->klass();
1925 if( !klass->is_loaded() )
1926 return _type; // Bail out if not loaded
1927 if( klass->is_obj_array_klass() &&
1928 (uint)tkls->offset() == objArrayKlass::element_klass_offset_in_bytes() + sizeof(oopDesc)) {
1929 ciKlass* elem = klass->as_obj_array_klass()->element_klass();
1930 // // Always returning precise element type is incorrect,
1931 // // e.g., element type could be object and array may contain strings
1932 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
1933
1934 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
1935 // according to the element type's subclassing.
1936 return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/);
1937 }
1938 if( klass->is_instance_klass() && tkls->klass_is_exact() &&
1939 (uint)tkls->offset() == Klass::super_offset_in_bytes() + sizeof(oopDesc)) {
1940 ciKlass* sup = klass->as_instance_klass()->super();
1941 // The field is Klass::_super. Return its (constant) value.
1942 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
1943 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR;
1944 }
1945 }
1946
1947 // Bailout case
1948 return LoadNode::Value(phase);
1949 }
1950
1951 //------------------------------Identity---------------------------------------
1952 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
1953 // Also feed through the klass in Allocate(...klass...)._klass.
1954 Node* LoadKlassNode::Identity( PhaseTransform *phase ) {
1955 return klass_identity_common(phase);
1956 }
1957
1958 Node* LoadNode::klass_identity_common(PhaseTransform *phase ) {
1959 Node* x = LoadNode::Identity(phase);
1960 if (x != this) return x;
1961
1962 // Take apart the address into an oop and and offset.
1963 // Return 'this' if we cannot.
1964 Node* adr = in(MemNode::Address);
1965 intptr_t offset = 0;
1966 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
1967 if (base == NULL) return this;
1968 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
1969 if (toop == NULL) return this;
1970
1971 // We can fetch the klass directly through an AllocateNode.
1972 // This works even if the klass is not constant (clone or newArray).
1973 if (offset == oopDesc::klass_offset_in_bytes()) {
1974 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
1975 if (allocated_klass != NULL) {
1976 return allocated_klass;
1977 }
1978 }
1979
1980 // Simplify k.java_mirror.as_klass to plain k, where k is a klassOop.
1981 // Simplify ak.component_mirror.array_klass to plain ak, ak an arrayKlass.
1982 // See inline_native_Class_query for occurrences of these patterns.
1983 // Java Example: x.getClass().isAssignableFrom(y)
1984 // Java Example: Array.newInstance(x.getClass().getComponentType(), n)
1985 //
1986 // This improves reflective code, often making the Class
1987 // mirror go completely dead. (Current exception: Class
1988 // mirrors may appear in debug info, but we could clean them out by
1989 // introducing a new debug info operator for klassOop.java_mirror).
1990 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass()
1991 && (offset == java_lang_Class::klass_offset_in_bytes() ||
1992 offset == java_lang_Class::array_klass_offset_in_bytes())) {
1993 // We are loading a special hidden field from a Class mirror,
1994 // the field which points to its Klass or arrayKlass metaobject.
1995 if (base->is_Load()) {
1996 Node* adr2 = base->in(MemNode::Address);
1997 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
1998 if (tkls != NULL && !tkls->empty()
1999 && (tkls->klass()->is_instance_klass() ||
2000 tkls->klass()->is_array_klass())
2001 && adr2->is_AddP()
2002 ) {
2003 int mirror_field = Klass::java_mirror_offset_in_bytes();
2004 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
2005 mirror_field = in_bytes(arrayKlass::component_mirror_offset());
2006 }
2007 if (tkls->offset() == mirror_field + (int)sizeof(oopDesc)) {
2008 return adr2->in(AddPNode::Base);
2009 }
2010 }
2011 }
2012 }
2013
2014 return this;
2015 }
2016
2017
2018 //------------------------------Value------------------------------------------
2019 const Type *LoadNKlassNode::Value( PhaseTransform *phase ) const {
2020 const Type *t = klass_value_common(phase);
2021 if (t == Type::TOP)
2022 return t;
2023
2024 return t->make_narrowoop();
2025 }
2026
2027 //------------------------------Identity---------------------------------------
2028 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
2029 // Also feed through the klass in Allocate(...klass...)._klass.
2030 Node* LoadNKlassNode::Identity( PhaseTransform *phase ) {
2031 Node *x = klass_identity_common(phase);
2032
2033 const Type *t = phase->type( x );
2034 if( t == Type::TOP ) return x;
2035 if( t->isa_narrowoop()) return x;
2036
2037 return phase->transform(new (phase->C, 2) EncodePNode(x, t->make_narrowoop()));
2038 }
2039
2040 //------------------------------Value-----------------------------------------
2041 const Type *LoadRangeNode::Value( PhaseTransform *phase ) const {
2042 // Either input is TOP ==> the result is TOP
2043 const Type *t1 = phase->type( in(MemNode::Memory) );
2044 if( t1 == Type::TOP ) return Type::TOP;
2045 Node *adr = in(MemNode::Address);
2046 const Type *t2 = phase->type( adr );
2047 if( t2 == Type::TOP ) return Type::TOP;
2048 const TypePtr *tp = t2->is_ptr();
2049 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
2050 const TypeAryPtr *tap = tp->isa_aryptr();
2051 if( !tap ) return _type;
2052 return tap->size();
2053 }
2054
2055 //-------------------------------Ideal---------------------------------------
2056 // Feed through the length in AllocateArray(...length...)._length.
2057 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2058 Node* p = MemNode::Ideal_common(phase, can_reshape);
2059 if (p) return (p == NodeSentinel) ? NULL : p;
2060
2061 // Take apart the address into an oop and and offset.
2062 // Return 'this' if we cannot.
2063 Node* adr = in(MemNode::Address);
2064 intptr_t offset = 0;
2065 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2066 if (base == NULL) return NULL;
2067 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2068 if (tary == NULL) return NULL;
2069
2070 // We can fetch the length directly through an AllocateArrayNode.
2071 // This works even if the length is not constant (clone or newArray).
2072 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2073 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2074 if (alloc != NULL) {
2075 Node* allocated_length = alloc->Ideal_length();
2076 Node* len = alloc->make_ideal_length(tary, phase);
2077 if (allocated_length != len) {
2078 // New CastII improves on this.
2079 return len;
2080 }
2081 }
2082 }
2083
2084 return NULL;
2085 }
2086
2087 //------------------------------Identity---------------------------------------
2088 // Feed through the length in AllocateArray(...length...)._length.
2089 Node* LoadRangeNode::Identity( PhaseTransform *phase ) {
2090 Node* x = LoadINode::Identity(phase);
2091 if (x != this) return x;
2092
2093 // Take apart the address into an oop and and offset.
2094 // Return 'this' if we cannot.
2095 Node* adr = in(MemNode::Address);
2096 intptr_t offset = 0;
2097 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2098 if (base == NULL) return this;
2099 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2100 if (tary == NULL) return this;
2101
2102 // We can fetch the length directly through an AllocateArrayNode.
2103 // This works even if the length is not constant (clone or newArray).
2104 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2105 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2106 if (alloc != NULL) {
2107 Node* allocated_length = alloc->Ideal_length();
2108 // Do not allow make_ideal_length to allocate a CastII node.
2109 Node* len = alloc->make_ideal_length(tary, phase, false);
2110 if (allocated_length == len) {
2111 // Return allocated_length only if it would not be improved by a CastII.
2112 return allocated_length;
2113 }
2114 }
2115 }
2116
2117 return this;
2118
2119 }
2120
2121 //=============================================================================
2122 //---------------------------StoreNode::make-----------------------------------
2123 // Polymorphic factory method:
2124 StoreNode* StoreNode::make( PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt ) {
2125 Compile* C = gvn.C;
2126 assert( C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2127 ctl != NULL, "raw memory operations should have control edge");
2128
2129 switch (bt) {
2130 case T_BOOLEAN:
2131 case T_BYTE: return new (C, 4) StoreBNode(ctl, mem, adr, adr_type, val);
2132 case T_INT: return new (C, 4) StoreINode(ctl, mem, adr, adr_type, val);
2133 case T_CHAR:
2134 case T_SHORT: return new (C, 4) StoreCNode(ctl, mem, adr, adr_type, val);
2135 case T_LONG: return new (C, 4) StoreLNode(ctl, mem, adr, adr_type, val);
2136 case T_FLOAT: return new (C, 4) StoreFNode(ctl, mem, adr, adr_type, val);
2137 case T_DOUBLE: return new (C, 4) StoreDNode(ctl, mem, adr, adr_type, val);
2138 case T_ADDRESS:
2139 case T_OBJECT:
2140 #ifdef _LP64
2141 if (adr->bottom_type()->is_ptr_to_narrowoop() ||
2142 (UseCompressedOops && val->bottom_type()->isa_klassptr() &&
2143 adr->bottom_type()->isa_rawptr())) {
2144 val = gvn.transform(new (C, 2) EncodePNode(val, val->bottom_type()->make_narrowoop()));
2145 return new (C, 4) StoreNNode(ctl, mem, adr, adr_type, val);
2146 } else
2147 #endif
2148 {
2149 return new (C, 4) StorePNode(ctl, mem, adr, adr_type, val);
2150 }
2151 }
2152 ShouldNotReachHere();
2153 return (StoreNode*)NULL;
2154 }
2155
2156 StoreLNode* StoreLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val) {
2157 bool require_atomic = true;
2158 return new (C, 4) StoreLNode(ctl, mem, adr, adr_type, val, require_atomic);
2159 }
2160
2161
2162 //--------------------------bottom_type----------------------------------------
2163 const Type *StoreNode::bottom_type() const {
2164 return Type::MEMORY;
2165 }
2166
2167 //------------------------------hash-------------------------------------------
2168 uint StoreNode::hash() const {
2169 // unroll addition of interesting fields
2170 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2171
2172 // Since they are not commoned, do not hash them:
2173 return NO_HASH;
2174 }
2175
2176 //------------------------------Ideal------------------------------------------
2177 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
2178 // When a store immediately follows a relevant allocation/initialization,
2179 // try to capture it into the initialization, or hoist it above.
2180 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2181 Node* p = MemNode::Ideal_common(phase, can_reshape);
2182 if (p) return (p == NodeSentinel) ? NULL : p;
2183
2184 Node* mem = in(MemNode::Memory);
2185 Node* address = in(MemNode::Address);
2186
2187 // Back-to-back stores to same address? Fold em up. Generally
2188 // unsafe if I have intervening uses... Also disallowed for StoreCM
2189 // since they must follow each StoreP operation. Redundant StoreCMs
2190 // are eliminated just before matching in final_graph_reshape.
2191 if (mem->is_Store() && phase->eqv_uncast(mem->in(MemNode::Address), address) &&
2192 mem->Opcode() != Op_StoreCM) {
2193 // Looking at a dead closed cycle of memory?
2194 assert(mem != mem->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
2195
2196 assert(Opcode() == mem->Opcode() ||
2197 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw,
2198 "no mismatched stores, except on raw memory");
2199
2200 if (mem->outcnt() == 1 && // check for intervening uses
2201 mem->as_Store()->memory_size() <= this->memory_size()) {
2202 // If anybody other than 'this' uses 'mem', we cannot fold 'mem' away.
2203 // For example, 'mem' might be the final state at a conditional return.
2204 // Or, 'mem' might be used by some node which is live at the same time
2205 // 'this' is live, which might be unschedulable. So, require exactly
2206 // ONE user, the 'this' store, until such time as we clone 'mem' for
2207 // each of 'mem's uses (thus making the exactly-1-user-rule hold true).
2208 if (can_reshape) { // (%%% is this an anachronism?)
2209 set_req_X(MemNode::Memory, mem->in(MemNode::Memory),
2210 phase->is_IterGVN());
2211 } else {
2212 // It's OK to do this in the parser, since DU info is always accurate,
2213 // and the parser always refers to nodes via SafePointNode maps.
2214 set_req(MemNode::Memory, mem->in(MemNode::Memory));
2215 }
2216 return this;
2217 }
2218 }
2219
2220 // Capture an unaliased, unconditional, simple store into an initializer.
2221 // Or, if it is independent of the allocation, hoist it above the allocation.
2222 if (ReduceFieldZeroing && /*can_reshape &&*/
2223 mem->is_Proj() && mem->in(0)->is_Initialize()) {
2224 InitializeNode* init = mem->in(0)->as_Initialize();
2225 intptr_t offset = init->can_capture_store(this, phase);
2226 if (offset > 0) {
2227 Node* moved = init->capture_store(this, offset, phase);
2228 // If the InitializeNode captured me, it made a raw copy of me,
2229 // and I need to disappear.
2230 if (moved != NULL) {
2231 // %%% hack to ensure that Ideal returns a new node:
2232 mem = MergeMemNode::make(phase->C, mem);
2233 return mem; // fold me away
2234 }
2235 }
2236 }
2237
2238 return NULL; // No further progress
2239 }
2240
2241 //------------------------------Value-----------------------------------------
2242 const Type *StoreNode::Value( PhaseTransform *phase ) const {
2243 // Either input is TOP ==> the result is TOP
2244 const Type *t1 = phase->type( in(MemNode::Memory) );
2245 if( t1 == Type::TOP ) return Type::TOP;
2246 const Type *t2 = phase->type( in(MemNode::Address) );
2247 if( t2 == Type::TOP ) return Type::TOP;
2248 const Type *t3 = phase->type( in(MemNode::ValueIn) );
2249 if( t3 == Type::TOP ) return Type::TOP;
2250 return Type::MEMORY;
2251 }
2252
2253 //------------------------------Identity---------------------------------------
2254 // Remove redundant stores:
2255 // Store(m, p, Load(m, p)) changes to m.
2256 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
2257 Node *StoreNode::Identity( PhaseTransform *phase ) {
2258 Node* mem = in(MemNode::Memory);
2259 Node* adr = in(MemNode::Address);
2260 Node* val = in(MemNode::ValueIn);
2261
2262 // Load then Store? Then the Store is useless
2263 if (val->is_Load() &&
2264 phase->eqv_uncast( val->in(MemNode::Address), adr ) &&
2265 phase->eqv_uncast( val->in(MemNode::Memory ), mem ) &&
2266 val->as_Load()->store_Opcode() == Opcode()) {
2267 return mem;
2268 }
2269
2270 // Two stores in a row of the same value?
2271 if (mem->is_Store() &&
2272 phase->eqv_uncast( mem->in(MemNode::Address), adr ) &&
2273 phase->eqv_uncast( mem->in(MemNode::ValueIn), val ) &&
2274 mem->Opcode() == Opcode()) {
2275 return mem;
2276 }
2277
2278 // Store of zero anywhere into a freshly-allocated object?
2279 // Then the store is useless.
2280 // (It must already have been captured by the InitializeNode.)
2281 if (ReduceFieldZeroing && phase->type(val)->is_zero_type()) {
2282 // a newly allocated object is already all-zeroes everywhere
2283 if (mem->is_Proj() && mem->in(0)->is_Allocate()) {
2284 return mem;
2285 }
2286
2287 // the store may also apply to zero-bits in an earlier object
2288 Node* prev_mem = find_previous_store(phase);
2289 // Steps (a), (b): Walk past independent stores to find an exact match.
2290 if (prev_mem != NULL) {
2291 Node* prev_val = can_see_stored_value(prev_mem, phase);
2292 if (prev_val != NULL && phase->eqv(prev_val, val)) {
2293 // prev_val and val might differ by a cast; it would be good
2294 // to keep the more informative of the two.
2295 return mem;
2296 }
2297 }
2298 }
2299
2300 return this;
2301 }
2302
2303 //------------------------------match_edge-------------------------------------
2304 // Do we Match on this edge index or not? Match only memory & value
2305 uint StoreNode::match_edge(uint idx) const {
2306 return idx == MemNode::Address || idx == MemNode::ValueIn;
2307 }
2308
2309 //------------------------------cmp--------------------------------------------
2310 // Do not common stores up together. They generally have to be split
2311 // back up anyways, so do not bother.
2312 uint StoreNode::cmp( const Node &n ) const {
2313 return (&n == this); // Always fail except on self
2314 }
2315
2316 //------------------------------Ideal_masked_input-----------------------------
2317 // Check for a useless mask before a partial-word store
2318 // (StoreB ... (AndI valIn conIa) )
2319 // If (conIa & mask == mask) this simplifies to
2320 // (StoreB ... (valIn) )
2321 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
2322 Node *val = in(MemNode::ValueIn);
2323 if( val->Opcode() == Op_AndI ) {
2324 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2325 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
2326 set_req(MemNode::ValueIn, val->in(1));
2327 return this;
2328 }
2329 }
2330 return NULL;
2331 }
2332
2333
2334 //------------------------------Ideal_sign_extended_input----------------------
2335 // Check for useless sign-extension before a partial-word store
2336 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) )
2337 // If (conIL == conIR && conIR <= num_bits) this simplifies to
2338 // (StoreB ... (valIn) )
2339 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) {
2340 Node *val = in(MemNode::ValueIn);
2341 if( val->Opcode() == Op_RShiftI ) {
2342 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2343 if( t && t->is_con() && (t->get_con() <= num_bits) ) {
2344 Node *shl = val->in(1);
2345 if( shl->Opcode() == Op_LShiftI ) {
2346 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int();
2347 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) {
2348 set_req(MemNode::ValueIn, shl->in(1));
2349 return this;
2350 }
2351 }
2352 }
2353 }
2354 return NULL;
2355 }
2356
2357 //------------------------------value_never_loaded-----------------------------------
2358 // Determine whether there are any possible loads of the value stored.
2359 // For simplicity, we actually check if there are any loads from the
2360 // address stored to, not just for loads of the value stored by this node.
2361 //
2362 bool StoreNode::value_never_loaded( PhaseTransform *phase) const {
2363 Node *adr = in(Address);
2364 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
2365 if (adr_oop == NULL)
2366 return false;
2367 if (!adr_oop->is_known_instance_field())
2368 return false; // if not a distinct instance, there may be aliases of the address
2369 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
2370 Node *use = adr->fast_out(i);
2371 int opc = use->Opcode();
2372 if (use->is_Load() || use->is_LoadStore()) {
2373 return false;
2374 }
2375 }
2376 return true;
2377 }
2378
2379 //=============================================================================
2380 //------------------------------Ideal------------------------------------------
2381 // If the store is from an AND mask that leaves the low bits untouched, then
2382 // we can skip the AND operation. If the store is from a sign-extension
2383 // (a left shift, then right shift) we can skip both.
2384 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
2385 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
2386 if( progress != NULL ) return progress;
2387
2388 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
2389 if( progress != NULL ) return progress;
2390
2391 // Finally check the default case
2392 return StoreNode::Ideal(phase, can_reshape);
2393 }
2394
2395 //=============================================================================
2396 //------------------------------Ideal------------------------------------------
2397 // If the store is from an AND mask that leaves the low bits untouched, then
2398 // we can skip the AND operation
2399 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
2400 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
2401 if( progress != NULL ) return progress;
2402
2403 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
2404 if( progress != NULL ) return progress;
2405
2406 // Finally check the default case
2407 return StoreNode::Ideal(phase, can_reshape);
2408 }
2409
2410 //=============================================================================
2411 //------------------------------Identity---------------------------------------
2412 Node *StoreCMNode::Identity( PhaseTransform *phase ) {
2413 // No need to card mark when storing a null ptr
2414 Node* my_store = in(MemNode::OopStore);
2415 if (my_store->is_Store()) {
2416 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) );
2417 if( t1 == TypePtr::NULL_PTR ) {
2418 return in(MemNode::Memory);
2419 }
2420 }
2421 return this;
2422 }
2423
2424 //=============================================================================
2425 //------------------------------Ideal---------------------------------------
2426 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){
2427 Node* progress = StoreNode::Ideal(phase, can_reshape);
2428 if (progress != NULL) return progress;
2429
2430 Node* my_store = in(MemNode::OopStore);
2431 if (my_store->is_MergeMem()) {
2432 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx());
2433 set_req(MemNode::OopStore, mem);
2434 return this;
2435 }
2436
2437 return NULL;
2438 }
2439
2440 //------------------------------Value-----------------------------------------
2441 const Type *StoreCMNode::Value( PhaseTransform *phase ) const {
2442 // Either input is TOP ==> the result is TOP
2443 const Type *t = phase->type( in(MemNode::Memory) );
2444 if( t == Type::TOP ) return Type::TOP;
2445 t = phase->type( in(MemNode::Address) );
2446 if( t == Type::TOP ) return Type::TOP;
2447 t = phase->type( in(MemNode::ValueIn) );
2448 if( t == Type::TOP ) return Type::TOP;
2449 // If extra input is TOP ==> the result is TOP
2450 t = phase->type( in(MemNode::OopStore) );
2451 if( t == Type::TOP ) return Type::TOP;
2452
2453 return StoreNode::Value( phase );
2454 }
2455
2456
2457 //=============================================================================
2458 //----------------------------------SCMemProjNode------------------------------
2459 const Type * SCMemProjNode::Value( PhaseTransform *phase ) const
2460 {
2461 return bottom_type();
2462 }
2463
2464 //=============================================================================
2465 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : Node(5) {
2466 init_req(MemNode::Control, c );
2467 init_req(MemNode::Memory , mem);
2468 init_req(MemNode::Address, adr);
2469 init_req(MemNode::ValueIn, val);
2470 init_req( ExpectedIn, ex );
2471 init_class_id(Class_LoadStore);
2472
2473 }
2474
2475 //=============================================================================
2476 //-------------------------------adr_type--------------------------------------
2477 // Do we Match on this edge index or not? Do not match memory
2478 const TypePtr* ClearArrayNode::adr_type() const {
2479 Node *adr = in(3);
2480 return MemNode::calculate_adr_type(adr->bottom_type());
2481 }
2482
2483 //------------------------------match_edge-------------------------------------
2484 // Do we Match on this edge index or not? Do not match memory
2485 uint ClearArrayNode::match_edge(uint idx) const {
2486 return idx > 1;
2487 }
2488
2489 //------------------------------Identity---------------------------------------
2490 // Clearing a zero length array does nothing
2491 Node *ClearArrayNode::Identity( PhaseTransform *phase ) {
2492 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
2493 }
2494
2495 //------------------------------Idealize---------------------------------------
2496 // Clearing a short array is faster with stores
2497 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape){
2498 const int unit = BytesPerLong;
2499 const TypeX* t = phase->type(in(2))->isa_intptr_t();
2500 if (!t) return NULL;
2501 if (!t->is_con()) return NULL;
2502 intptr_t raw_count = t->get_con();
2503 intptr_t size = raw_count;
2504 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
2505 // Clearing nothing uses the Identity call.
2506 // Negative clears are possible on dead ClearArrays
2507 // (see jck test stmt114.stmt11402.val).
2508 if (size <= 0 || size % unit != 0) return NULL;
2509 intptr_t count = size / unit;
2510 // Length too long; use fast hardware clear
2511 if (size > Matcher::init_array_short_size) return NULL;
2512 Node *mem = in(1);
2513 if( phase->type(mem)==Type::TOP ) return NULL;
2514 Node *adr = in(3);
2515 const Type* at = phase->type(adr);
2516 if( at==Type::TOP ) return NULL;
2517 const TypePtr* atp = at->isa_ptr();
2518 // adjust atp to be the correct array element address type
2519 if (atp == NULL) atp = TypePtr::BOTTOM;
2520 else atp = atp->add_offset(Type::OffsetBot);
2521 // Get base for derived pointer purposes
2522 if( adr->Opcode() != Op_AddP ) Unimplemented();
2523 Node *base = adr->in(1);
2524
2525 Node *zero = phase->makecon(TypeLong::ZERO);
2526 Node *off = phase->MakeConX(BytesPerLong);
2527 mem = new (phase->C, 4) StoreLNode(in(0),mem,adr,atp,zero);
2528 count--;
2529 while( count-- ) {
2530 mem = phase->transform(mem);
2531 adr = phase->transform(new (phase->C, 4) AddPNode(base,adr,off));
2532 mem = new (phase->C, 4) StoreLNode(in(0),mem,adr,atp,zero);
2533 }
2534 return mem;
2535 }
2536
2537 //----------------------------step_through----------------------------------
2538 // Return allocation input memory edge if it is different instance
2539 // or itself if it is the one we are looking for.
2540 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) {
2541 Node* n = *np;
2542 assert(n->is_ClearArray(), "sanity");
2543 intptr_t offset;
2544 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
2545 // This method is called only before Allocate nodes are expanded during
2546 // macro nodes expansion. Before that ClearArray nodes are only generated
2547 // in LibraryCallKit::generate_arraycopy() which follows allocations.
2548 assert(alloc != NULL, "should have allocation");
2549 if (alloc->_idx == instance_id) {
2550 // Can not bypass initialization of the instance we are looking for.
2551 return false;
2552 }
2553 // Otherwise skip it.
2554 InitializeNode* init = alloc->initialization();
2555 if (init != NULL)
2556 *np = init->in(TypeFunc::Memory);
2557 else
2558 *np = alloc->in(TypeFunc::Memory);
2559 return true;
2560 }
2561
2562 //----------------------------clear_memory-------------------------------------
2563 // Generate code to initialize object storage to zero.
2564 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2565 intptr_t start_offset,
2566 Node* end_offset,
2567 PhaseGVN* phase) {
2568 Compile* C = phase->C;
2569 intptr_t offset = start_offset;
2570
2571 int unit = BytesPerLong;
2572 if ((offset % unit) != 0) {
2573 Node* adr = new (C, 4) AddPNode(dest, dest, phase->MakeConX(offset));
2574 adr = phase->transform(adr);
2575 const TypePtr* atp = TypeRawPtr::BOTTOM;
2576 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT);
2577 mem = phase->transform(mem);
2578 offset += BytesPerInt;
2579 }
2580 assert((offset % unit) == 0, "");
2581
2582 // Initialize the remaining stuff, if any, with a ClearArray.
2583 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase);
2584 }
2585
2586 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2587 Node* start_offset,
2588 Node* end_offset,
2589 PhaseGVN* phase) {
2590 if (start_offset == end_offset) {
2591 // nothing to do
2592 return mem;
2593 }
2594
2595 Compile* C = phase->C;
2596 int unit = BytesPerLong;
2597 Node* zbase = start_offset;
2598 Node* zend = end_offset;
2599
2600 // Scale to the unit required by the CPU:
2601 if (!Matcher::init_array_count_is_in_bytes) {
2602 Node* shift = phase->intcon(exact_log2(unit));
2603 zbase = phase->transform( new(C,3) URShiftXNode(zbase, shift) );
2604 zend = phase->transform( new(C,3) URShiftXNode(zend, shift) );
2605 }
2606
2607 Node* zsize = phase->transform( new(C,3) SubXNode(zend, zbase) );
2608 Node* zinit = phase->zerocon((unit == BytesPerLong) ? T_LONG : T_INT);
2609
2610 // Bulk clear double-words
2611 Node* adr = phase->transform( new(C,4) AddPNode(dest, dest, start_offset) );
2612 mem = new (C, 4) ClearArrayNode(ctl, mem, zsize, adr);
2613 return phase->transform(mem);
2614 }
2615
2616 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2617 intptr_t start_offset,
2618 intptr_t end_offset,
2619 PhaseGVN* phase) {
2620 if (start_offset == end_offset) {
2621 // nothing to do
2622 return mem;
2623 }
2624
2625 Compile* C = phase->C;
2626 assert((end_offset % BytesPerInt) == 0, "odd end offset");
2627 intptr_t done_offset = end_offset;
2628 if ((done_offset % BytesPerLong) != 0) {
2629 done_offset -= BytesPerInt;
2630 }
2631 if (done_offset > start_offset) {
2632 mem = clear_memory(ctl, mem, dest,
2633 start_offset, phase->MakeConX(done_offset), phase);
2634 }
2635 if (done_offset < end_offset) { // emit the final 32-bit store
2636 Node* adr = new (C, 4) AddPNode(dest, dest, phase->MakeConX(done_offset));
2637 adr = phase->transform(adr);
2638 const TypePtr* atp = TypeRawPtr::BOTTOM;
2639 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT);
2640 mem = phase->transform(mem);
2641 done_offset += BytesPerInt;
2642 }
2643 assert(done_offset == end_offset, "");
2644 return mem;
2645 }
2646
2647 //=============================================================================
2648 // Do not match memory edge.
2649 uint StrIntrinsicNode::match_edge(uint idx) const {
2650 return idx == 2 || idx == 3;
2651 }
2652
2653 //------------------------------Ideal------------------------------------------
2654 // Return a node which is more "ideal" than the current node. Strip out
2655 // control copies
2656 Node *StrIntrinsicNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2657 if (remove_dead_region(phase, can_reshape)) return this;
2658
2659 if (can_reshape) {
2660 Node* mem = phase->transform(in(MemNode::Memory));
2661 // If transformed to a MergeMem, get the desired slice
2662 uint alias_idx = phase->C->get_alias_index(adr_type());
2663 mem = mem->is_MergeMem() ? mem->as_MergeMem()->memory_at(alias_idx) : mem;
2664 if (mem != in(MemNode::Memory)) {
2665 set_req(MemNode::Memory, mem);
2666 return this;
2667 }
2668 }
2669 return NULL;
2670 }
2671
2672 //=============================================================================
2673 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
2674 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)),
2675 _adr_type(C->get_adr_type(alias_idx))
2676 {
2677 init_class_id(Class_MemBar);
2678 Node* top = C->top();
2679 init_req(TypeFunc::I_O,top);
2680 init_req(TypeFunc::FramePtr,top);
2681 init_req(TypeFunc::ReturnAdr,top);
2682 if (precedent != NULL)
2683 init_req(TypeFunc::Parms, precedent);
2684 }
2685
2686 //------------------------------cmp--------------------------------------------
2687 uint MemBarNode::hash() const { return NO_HASH; }
2688 uint MemBarNode::cmp( const Node &n ) const {
2689 return (&n == this); // Always fail except on self
2690 }
2691
2692 //------------------------------make-------------------------------------------
2693 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
2694 int len = Precedent + (pn == NULL? 0: 1);
2695 switch (opcode) {
2696 case Op_MemBarAcquire: return new(C, len) MemBarAcquireNode(C, atp, pn);
2697 case Op_MemBarRelease: return new(C, len) MemBarReleaseNode(C, atp, pn);
2698 case Op_MemBarAcquireLock: return new(C, len) MemBarAcquireLockNode(C, atp, pn);
2699 case Op_MemBarReleaseLock: return new(C, len) MemBarReleaseLockNode(C, atp, pn);
2700 case Op_MemBarVolatile: return new(C, len) MemBarVolatileNode(C, atp, pn);
2701 case Op_MemBarCPUOrder: return new(C, len) MemBarCPUOrderNode(C, atp, pn);
2702 case Op_Initialize: return new(C, len) InitializeNode(C, atp, pn);
2703 default: ShouldNotReachHere(); return NULL;
2704 }
2705 }
2706
2707 //------------------------------Ideal------------------------------------------
2708 // Return a node which is more "ideal" than the current node. Strip out
2709 // control copies
2710 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2711 if (remove_dead_region(phase, can_reshape)) return this;
2712
2713 // Eliminate volatile MemBars for scalar replaced objects.
2714 if (can_reshape && req() == (Precedent+1) &&
2715 (Opcode() == Op_MemBarAcquire || Opcode() == Op_MemBarVolatile)) {
2716 // Volatile field loads and stores.
2717 Node* my_mem = in(MemBarNode::Precedent);
2718 if (my_mem != NULL && my_mem->is_Mem()) {
2719 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
2720 // Check for scalar replaced object reference.
2721 if( t_oop != NULL && t_oop->is_known_instance_field() &&
2722 t_oop->offset() != Type::OffsetBot &&
2723 t_oop->offset() != Type::OffsetTop) {
2724 // Replace MemBar projections by its inputs.
2725 PhaseIterGVN* igvn = phase->is_IterGVN();
2726 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
2727 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
2728 // Must return either the original node (now dead) or a new node
2729 // (Do not return a top here, since that would break the uniqueness of top.)
2730 return new (phase->C, 1) ConINode(TypeInt::ZERO);
2731 }
2732 }
2733 }
2734 return NULL;
2735 }
2736
2737 //------------------------------Value------------------------------------------
2738 const Type *MemBarNode::Value( PhaseTransform *phase ) const {
2739 if( !in(0) ) return Type::TOP;
2740 if( phase->type(in(0)) == Type::TOP )
2741 return Type::TOP;
2742 return TypeTuple::MEMBAR;
2743 }
2744
2745 //------------------------------match------------------------------------------
2746 // Construct projections for memory.
2747 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) {
2748 switch (proj->_con) {
2749 case TypeFunc::Control:
2750 case TypeFunc::Memory:
2751 return new (m->C, 1) MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
2752 }
2753 ShouldNotReachHere();
2754 return NULL;
2755 }
2756
2757 //===========================InitializeNode====================================
2758 // SUMMARY:
2759 // This node acts as a memory barrier on raw memory, after some raw stores.
2760 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
2761 // The Initialize can 'capture' suitably constrained stores as raw inits.
2762 // It can coalesce related raw stores into larger units (called 'tiles').
2763 // It can avoid zeroing new storage for memory units which have raw inits.
2764 // At macro-expansion, it is marked 'complete', and does not optimize further.
2765 //
2766 // EXAMPLE:
2767 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
2768 // ctl = incoming control; mem* = incoming memory
2769 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
2770 // First allocate uninitialized memory and fill in the header:
2771 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
2772 // ctl := alloc.Control; mem* := alloc.Memory*
2773 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
2774 // Then initialize to zero the non-header parts of the raw memory block:
2775 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
2776 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
2777 // After the initialize node executes, the object is ready for service:
2778 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
2779 // Suppose its body is immediately initialized as {1,2}:
2780 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
2781 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
2782 // mem.SLICE(#short[*]) := store2
2783 //
2784 // DETAILS:
2785 // An InitializeNode collects and isolates object initialization after
2786 // an AllocateNode and before the next possible safepoint. As a
2787 // memory barrier (MemBarNode), it keeps critical stores from drifting
2788 // down past any safepoint or any publication of the allocation.
2789 // Before this barrier, a newly-allocated object may have uninitialized bits.
2790 // After this barrier, it may be treated as a real oop, and GC is allowed.
2791 //
2792 // The semantics of the InitializeNode include an implicit zeroing of
2793 // the new object from object header to the end of the object.
2794 // (The object header and end are determined by the AllocateNode.)
2795 //
2796 // Certain stores may be added as direct inputs to the InitializeNode.
2797 // These stores must update raw memory, and they must be to addresses
2798 // derived from the raw address produced by AllocateNode, and with
2799 // a constant offset. They must be ordered by increasing offset.
2800 // The first one is at in(RawStores), the last at in(req()-1).
2801 // Unlike most memory operations, they are not linked in a chain,
2802 // but are displayed in parallel as users of the rawmem output of
2803 // the allocation.
2804 //
2805 // (See comments in InitializeNode::capture_store, which continue
2806 // the example given above.)
2807 //
2808 // When the associated Allocate is macro-expanded, the InitializeNode
2809 // may be rewritten to optimize collected stores. A ClearArrayNode
2810 // may also be created at that point to represent any required zeroing.
2811 // The InitializeNode is then marked 'complete', prohibiting further
2812 // capturing of nearby memory operations.
2813 //
2814 // During macro-expansion, all captured initializations which store
2815 // constant values of 32 bits or smaller are coalesced (if advantageous)
2816 // into larger 'tiles' 32 or 64 bits. This allows an object to be
2817 // initialized in fewer memory operations. Memory words which are
2818 // covered by neither tiles nor non-constant stores are pre-zeroed
2819 // by explicit stores of zero. (The code shape happens to do all
2820 // zeroing first, then all other stores, with both sequences occurring
2821 // in order of ascending offsets.)
2822 //
2823 // Alternatively, code may be inserted between an AllocateNode and its
2824 // InitializeNode, to perform arbitrary initialization of the new object.
2825 // E.g., the object copying intrinsics insert complex data transfers here.
2826 // The initialization must then be marked as 'complete' disable the
2827 // built-in zeroing semantics and the collection of initializing stores.
2828 //
2829 // While an InitializeNode is incomplete, reads from the memory state
2830 // produced by it are optimizable if they match the control edge and
2831 // new oop address associated with the allocation/initialization.
2832 // They return a stored value (if the offset matches) or else zero.
2833 // A write to the memory state, if it matches control and address,
2834 // and if it is to a constant offset, may be 'captured' by the
2835 // InitializeNode. It is cloned as a raw memory operation and rewired
2836 // inside the initialization, to the raw oop produced by the allocation.
2837 // Operations on addresses which are provably distinct (e.g., to
2838 // other AllocateNodes) are allowed to bypass the initialization.
2839 //
2840 // The effect of all this is to consolidate object initialization
2841 // (both arrays and non-arrays, both piecewise and bulk) into a
2842 // single location, where it can be optimized as a unit.
2843 //
2844 // Only stores with an offset less than TrackedInitializationLimit words
2845 // will be considered for capture by an InitializeNode. This puts a
2846 // reasonable limit on the complexity of optimized initializations.
2847
2848 //---------------------------InitializeNode------------------------------------
2849 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
2850 : _is_complete(Incomplete),
2851 MemBarNode(C, adr_type, rawoop)
2852 {
2853 init_class_id(Class_Initialize);
2854
2855 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
2856 assert(in(RawAddress) == rawoop, "proper init");
2857 // Note: allocation() can be NULL, for secondary initialization barriers
2858 }
2859
2860 // Since this node is not matched, it will be processed by the
2861 // register allocator. Declare that there are no constraints
2862 // on the allocation of the RawAddress edge.
2863 const RegMask &InitializeNode::in_RegMask(uint idx) const {
2864 // This edge should be set to top, by the set_complete. But be conservative.
2865 if (idx == InitializeNode::RawAddress)
2866 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
2867 return RegMask::Empty;
2868 }
2869
2870 Node* InitializeNode::memory(uint alias_idx) {
2871 Node* mem = in(Memory);
2872 if (mem->is_MergeMem()) {
2873 return mem->as_MergeMem()->memory_at(alias_idx);
2874 } else {
2875 // incoming raw memory is not split
2876 return mem;
2877 }
2878 }
2879
2880 bool InitializeNode::is_non_zero() {
2881 if (is_complete()) return false;
2882 remove_extra_zeroes();
2883 return (req() > RawStores);
2884 }
2885
2886 void InitializeNode::set_complete(PhaseGVN* phase) {
2887 assert(!is_complete(), "caller responsibility");
2888 _is_complete = Complete;
2889
2890 // After this node is complete, it contains a bunch of
2891 // raw-memory initializations. There is no need for
2892 // it to have anything to do with non-raw memory effects.
2893 // Therefore, tell all non-raw users to re-optimize themselves,
2894 // after skipping the memory effects of this initialization.
2895 PhaseIterGVN* igvn = phase->is_IterGVN();
2896 if (igvn) igvn->add_users_to_worklist(this);
2897 }
2898
2899 // convenience function
2900 // return false if the init contains any stores already
2901 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
2902 InitializeNode* init = initialization();
2903 if (init == NULL || init->is_complete()) return false;
2904 init->remove_extra_zeroes();
2905 // for now, if this allocation has already collected any inits, bail:
2906 if (init->is_non_zero()) return false;
2907 init->set_complete(phase);
2908 return true;
2909 }
2910
2911 void InitializeNode::remove_extra_zeroes() {
2912 if (req() == RawStores) return;
2913 Node* zmem = zero_memory();
2914 uint fill = RawStores;
2915 for (uint i = fill; i < req(); i++) {
2916 Node* n = in(i);
2917 if (n->is_top() || n == zmem) continue; // skip
2918 if (fill < i) set_req(fill, n); // compact
2919 ++fill;
2920 }
2921 // delete any empty spaces created:
2922 while (fill < req()) {
2923 del_req(fill);
2924 }
2925 }
2926
2927 // Helper for remembering which stores go with which offsets.
2928 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) {
2929 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
2930 intptr_t offset = -1;
2931 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
2932 phase, offset);
2933 if (base == NULL) return -1; // something is dead,
2934 if (offset < 0) return -1; // dead, dead
2935 return offset;
2936 }
2937
2938 // Helper for proving that an initialization expression is
2939 // "simple enough" to be folded into an object initialization.
2940 // Attempts to prove that a store's initial value 'n' can be captured
2941 // within the initialization without creating a vicious cycle, such as:
2942 // { Foo p = new Foo(); p.next = p; }
2943 // True for constants and parameters and small combinations thereof.
2944 bool InitializeNode::detect_init_independence(Node* n,
2945 bool st_is_pinned,
2946 int& count) {
2947 if (n == NULL) return true; // (can this really happen?)
2948 if (n->is_Proj()) n = n->in(0);
2949 if (n == this) return false; // found a cycle
2950 if (n->is_Con()) return true;
2951 if (n->is_Start()) return true; // params, etc., are OK
2952 if (n->is_Root()) return true; // even better
2953
2954 Node* ctl = n->in(0);
2955 if (ctl != NULL && !ctl->is_top()) {
2956 if (ctl->is_Proj()) ctl = ctl->in(0);
2957 if (ctl == this) return false;
2958
2959 // If we already know that the enclosing memory op is pinned right after
2960 // the init, then any control flow that the store has picked up
2961 // must have preceded the init, or else be equal to the init.
2962 // Even after loop optimizations (which might change control edges)
2963 // a store is never pinned *before* the availability of its inputs.
2964 if (!MemNode::all_controls_dominate(n, this))
2965 return false; // failed to prove a good control
2966
2967 }
2968
2969 // Check data edges for possible dependencies on 'this'.
2970 if ((count += 1) > 20) return false; // complexity limit
2971 for (uint i = 1; i < n->req(); i++) {
2972 Node* m = n->in(i);
2973 if (m == NULL || m == n || m->is_top()) continue;
2974 uint first_i = n->find_edge(m);
2975 if (i != first_i) continue; // process duplicate edge just once
2976 if (!detect_init_independence(m, st_is_pinned, count)) {
2977 return false;
2978 }
2979 }
2980
2981 return true;
2982 }
2983
2984 // Here are all the checks a Store must pass before it can be moved into
2985 // an initialization. Returns zero if a check fails.
2986 // On success, returns the (constant) offset to which the store applies,
2987 // within the initialized memory.
2988 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase) {
2989 const int FAIL = 0;
2990 if (st->req() != MemNode::ValueIn + 1)
2991 return FAIL; // an inscrutable StoreNode (card mark?)
2992 Node* ctl = st->in(MemNode::Control);
2993 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this))
2994 return FAIL; // must be unconditional after the initialization
2995 Node* mem = st->in(MemNode::Memory);
2996 if (!(mem->is_Proj() && mem->in(0) == this))
2997 return FAIL; // must not be preceded by other stores
2998 Node* adr = st->in(MemNode::Address);
2999 intptr_t offset;
3000 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
3001 if (alloc == NULL)
3002 return FAIL; // inscrutable address
3003 if (alloc != allocation())
3004 return FAIL; // wrong allocation! (store needs to float up)
3005 Node* val = st->in(MemNode::ValueIn);
3006 int complexity_count = 0;
3007 if (!detect_init_independence(val, true, complexity_count))
3008 return FAIL; // stored value must be 'simple enough'
3009
3010 return offset; // success
3011 }
3012
3013 // Find the captured store in(i) which corresponds to the range
3014 // [start..start+size) in the initialized object.
3015 // If there is one, return its index i. If there isn't, return the
3016 // negative of the index where it should be inserted.
3017 // Return 0 if the queried range overlaps an initialization boundary
3018 // or if dead code is encountered.
3019 // If size_in_bytes is zero, do not bother with overlap checks.
3020 int InitializeNode::captured_store_insertion_point(intptr_t start,
3021 int size_in_bytes,
3022 PhaseTransform* phase) {
3023 const int FAIL = 0, MAX_STORE = BytesPerLong;
3024
3025 if (is_complete())
3026 return FAIL; // arraycopy got here first; punt
3027
3028 assert(allocation() != NULL, "must be present");
3029
3030 // no negatives, no header fields:
3031 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
3032
3033 // after a certain size, we bail out on tracking all the stores:
3034 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3035 if (start >= ti_limit) return FAIL;
3036
3037 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
3038 if (i >= limit) return -(int)i; // not found; here is where to put it
3039
3040 Node* st = in(i);
3041 intptr_t st_off = get_store_offset(st, phase);
3042 if (st_off < 0) {
3043 if (st != zero_memory()) {
3044 return FAIL; // bail out if there is dead garbage
3045 }
3046 } else if (st_off > start) {
3047 // ...we are done, since stores are ordered
3048 if (st_off < start + size_in_bytes) {
3049 return FAIL; // the next store overlaps
3050 }
3051 return -(int)i; // not found; here is where to put it
3052 } else if (st_off < start) {
3053 if (size_in_bytes != 0 &&
3054 start < st_off + MAX_STORE &&
3055 start < st_off + st->as_Store()->memory_size()) {
3056 return FAIL; // the previous store overlaps
3057 }
3058 } else {
3059 if (size_in_bytes != 0 &&
3060 st->as_Store()->memory_size() != size_in_bytes) {
3061 return FAIL; // mismatched store size
3062 }
3063 return i;
3064 }
3065
3066 ++i;
3067 }
3068 }
3069
3070 // Look for a captured store which initializes at the offset 'start'
3071 // with the given size. If there is no such store, and no other
3072 // initialization interferes, then return zero_memory (the memory
3073 // projection of the AllocateNode).
3074 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
3075 PhaseTransform* phase) {
3076 assert(stores_are_sane(phase), "");
3077 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3078 if (i == 0) {
3079 return NULL; // something is dead
3080 } else if (i < 0) {
3081 return zero_memory(); // just primordial zero bits here
3082 } else {
3083 Node* st = in(i); // here is the store at this position
3084 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
3085 return st;
3086 }
3087 }
3088
3089 // Create, as a raw pointer, an address within my new object at 'offset'.
3090 Node* InitializeNode::make_raw_address(intptr_t offset,
3091 PhaseTransform* phase) {
3092 Node* addr = in(RawAddress);
3093 if (offset != 0) {
3094 Compile* C = phase->C;
3095 addr = phase->transform( new (C, 4) AddPNode(C->top(), addr,
3096 phase->MakeConX(offset)) );
3097 }
3098 return addr;
3099 }
3100
3101 // Clone the given store, converting it into a raw store
3102 // initializing a field or element of my new object.
3103 // Caller is responsible for retiring the original store,
3104 // with subsume_node or the like.
3105 //
3106 // From the example above InitializeNode::InitializeNode,
3107 // here are the old stores to be captured:
3108 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3109 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3110 //
3111 // Here is the changed code; note the extra edges on init:
3112 // alloc = (Allocate ...)
3113 // rawoop = alloc.RawAddress
3114 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
3115 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
3116 // init = (Initialize alloc.Control alloc.Memory rawoop
3117 // rawstore1 rawstore2)
3118 //
3119 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
3120 PhaseTransform* phase) {
3121 assert(stores_are_sane(phase), "");
3122
3123 if (start < 0) return NULL;
3124 assert(can_capture_store(st, phase) == start, "sanity");
3125
3126 Compile* C = phase->C;
3127 int size_in_bytes = st->memory_size();
3128 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3129 if (i == 0) return NULL; // bail out
3130 Node* prev_mem = NULL; // raw memory for the captured store
3131 if (i > 0) {
3132 prev_mem = in(i); // there is a pre-existing store under this one
3133 set_req(i, C->top()); // temporarily disconnect it
3134 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
3135 } else {
3136 i = -i; // no pre-existing store
3137 prev_mem = zero_memory(); // a slice of the newly allocated object
3138 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
3139 set_req(--i, C->top()); // reuse this edge; it has been folded away
3140 else
3141 ins_req(i, C->top()); // build a new edge
3142 }
3143 Node* new_st = st->clone();
3144 new_st->set_req(MemNode::Control, in(Control));
3145 new_st->set_req(MemNode::Memory, prev_mem);
3146 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
3147 new_st = phase->transform(new_st);
3148
3149 // At this point, new_st might have swallowed a pre-existing store
3150 // at the same offset, or perhaps new_st might have disappeared,
3151 // if it redundantly stored the same value (or zero to fresh memory).
3152
3153 // In any case, wire it in:
3154 set_req(i, new_st);
3155
3156 // The caller may now kill the old guy.
3157 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
3158 assert(check_st == new_st || check_st == NULL, "must be findable");
3159 assert(!is_complete(), "");
3160 return new_st;
3161 }
3162
3163 static bool store_constant(jlong* tiles, int num_tiles,
3164 intptr_t st_off, int st_size,
3165 jlong con) {
3166 if ((st_off & (st_size-1)) != 0)
3167 return false; // strange store offset (assume size==2**N)
3168 address addr = (address)tiles + st_off;
3169 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
3170 switch (st_size) {
3171 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
3172 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
3173 case sizeof(jint): *(jint*) addr = (jint) con; break;
3174 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
3175 default: return false; // strange store size (detect size!=2**N here)
3176 }
3177 return true; // return success to caller
3178 }
3179
3180 // Coalesce subword constants into int constants and possibly
3181 // into long constants. The goal, if the CPU permits,
3182 // is to initialize the object with a small number of 64-bit tiles.
3183 // Also, convert floating-point constants to bit patterns.
3184 // Non-constants are not relevant to this pass.
3185 //
3186 // In terms of the running example on InitializeNode::InitializeNode
3187 // and InitializeNode::capture_store, here is the transformation
3188 // of rawstore1 and rawstore2 into rawstore12:
3189 // alloc = (Allocate ...)
3190 // rawoop = alloc.RawAddress
3191 // tile12 = 0x00010002
3192 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
3193 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
3194 //
3195 void
3196 InitializeNode::coalesce_subword_stores(intptr_t header_size,
3197 Node* size_in_bytes,
3198 PhaseGVN* phase) {
3199 Compile* C = phase->C;
3200
3201 assert(stores_are_sane(phase), "");
3202 // Note: After this pass, they are not completely sane,
3203 // since there may be some overlaps.
3204
3205 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
3206
3207 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3208 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
3209 size_limit = MIN2(size_limit, ti_limit);
3210 size_limit = align_size_up(size_limit, BytesPerLong);
3211 int num_tiles = size_limit / BytesPerLong;
3212
3213 // allocate space for the tile map:
3214 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
3215 jlong tiles_buf[small_len];
3216 Node* nodes_buf[small_len];
3217 jlong inits_buf[small_len];
3218 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
3219 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3220 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
3221 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
3222 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
3223 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3224 // tiles: exact bitwise model of all primitive constants
3225 // nodes: last constant-storing node subsumed into the tiles model
3226 // inits: which bytes (in each tile) are touched by any initializations
3227
3228 //// Pass A: Fill in the tile model with any relevant stores.
3229
3230 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
3231 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
3232 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
3233 Node* zmem = zero_memory(); // initially zero memory state
3234 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3235 Node* st = in(i);
3236 intptr_t st_off = get_store_offset(st, phase);
3237
3238 // Figure out the store's offset and constant value:
3239 if (st_off < header_size) continue; //skip (ignore header)
3240 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
3241 int st_size = st->as_Store()->memory_size();
3242 if (st_off + st_size > size_limit) break;
3243
3244 // Record which bytes are touched, whether by constant or not.
3245 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
3246 continue; // skip (strange store size)
3247
3248 const Type* val = phase->type(st->in(MemNode::ValueIn));
3249 if (!val->singleton()) continue; //skip (non-con store)
3250 BasicType type = val->basic_type();
3251
3252 jlong con = 0;
3253 switch (type) {
3254 case T_INT: con = val->is_int()->get_con(); break;
3255 case T_LONG: con = val->is_long()->get_con(); break;
3256 case T_FLOAT: con = jint_cast(val->getf()); break;
3257 case T_DOUBLE: con = jlong_cast(val->getd()); break;
3258 default: continue; //skip (odd store type)
3259 }
3260
3261 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
3262 st->Opcode() == Op_StoreL) {
3263 continue; // This StoreL is already optimal.
3264 }
3265
3266 // Store down the constant.
3267 store_constant(tiles, num_tiles, st_off, st_size, con);
3268
3269 intptr_t j = st_off >> LogBytesPerLong;
3270
3271 if (type == T_INT && st_size == BytesPerInt
3272 && (st_off & BytesPerInt) == BytesPerInt) {
3273 jlong lcon = tiles[j];
3274 if (!Matcher::isSimpleConstant64(lcon) &&
3275 st->Opcode() == Op_StoreI) {
3276 // This StoreI is already optimal by itself.
3277 jint* intcon = (jint*) &tiles[j];
3278 intcon[1] = 0; // undo the store_constant()
3279
3280 // If the previous store is also optimal by itself, back up and
3281 // undo the action of the previous loop iteration... if we can.
3282 // But if we can't, just let the previous half take care of itself.
3283 st = nodes[j];
3284 st_off -= BytesPerInt;
3285 con = intcon[0];
3286 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) {
3287 assert(st_off >= header_size, "still ignoring header");
3288 assert(get_store_offset(st, phase) == st_off, "must be");
3289 assert(in(i-1) == zmem, "must be");
3290 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
3291 assert(con == tcon->is_int()->get_con(), "must be");
3292 // Undo the effects of the previous loop trip, which swallowed st:
3293 intcon[0] = 0; // undo store_constant()
3294 set_req(i-1, st); // undo set_req(i, zmem)
3295 nodes[j] = NULL; // undo nodes[j] = st
3296 --old_subword; // undo ++old_subword
3297 }
3298 continue; // This StoreI is already optimal.
3299 }
3300 }
3301
3302 // This store is not needed.
3303 set_req(i, zmem);
3304 nodes[j] = st; // record for the moment
3305 if (st_size < BytesPerLong) // something has changed
3306 ++old_subword; // includes int/float, but who's counting...
3307 else ++old_long;
3308 }
3309
3310 if ((old_subword + old_long) == 0)
3311 return; // nothing more to do
3312
3313 //// Pass B: Convert any non-zero tiles into optimal constant stores.
3314 // Be sure to insert them before overlapping non-constant stores.
3315 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
3316 for (int j = 0; j < num_tiles; j++) {
3317 jlong con = tiles[j];
3318 jlong init = inits[j];
3319 if (con == 0) continue;
3320 jint con0, con1; // split the constant, address-wise
3321 jint init0, init1; // split the init map, address-wise
3322 { union { jlong con; jint intcon[2]; } u;
3323 u.con = con;
3324 con0 = u.intcon[0];
3325 con1 = u.intcon[1];
3326 u.con = init;
3327 init0 = u.intcon[0];
3328 init1 = u.intcon[1];
3329 }
3330
3331 Node* old = nodes[j];
3332 assert(old != NULL, "need the prior store");
3333 intptr_t offset = (j * BytesPerLong);
3334
3335 bool split = !Matcher::isSimpleConstant64(con);
3336
3337 if (offset < header_size) {
3338 assert(offset + BytesPerInt >= header_size, "second int counts");
3339 assert(*(jint*)&tiles[j] == 0, "junk in header");
3340 split = true; // only the second word counts
3341 // Example: int a[] = { 42 ... }
3342 } else if (con0 == 0 && init0 == -1) {
3343 split = true; // first word is covered by full inits
3344 // Example: int a[] = { ... foo(), 42 ... }
3345 } else if (con1 == 0 && init1 == -1) {
3346 split = true; // second word is covered by full inits
3347 // Example: int a[] = { ... 42, foo() ... }
3348 }
3349
3350 // Here's a case where init0 is neither 0 nor -1:
3351 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
3352 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
3353 // In this case the tile is not split; it is (jlong)42.
3354 // The big tile is stored down, and then the foo() value is inserted.
3355 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
3356
3357 Node* ctl = old->in(MemNode::Control);
3358 Node* adr = make_raw_address(offset, phase);
3359 const TypePtr* atp = TypeRawPtr::BOTTOM;
3360
3361 // One or two coalesced stores to plop down.
3362 Node* st[2];
3363 intptr_t off[2];
3364 int nst = 0;
3365 if (!split) {
3366 ++new_long;
3367 off[nst] = offset;
3368 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3369 phase->longcon(con), T_LONG);
3370 } else {
3371 // Omit either if it is a zero.
3372 if (con0 != 0) {
3373 ++new_int;
3374 off[nst] = offset;
3375 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3376 phase->intcon(con0), T_INT);
3377 }
3378 if (con1 != 0) {
3379 ++new_int;
3380 offset += BytesPerInt;
3381 adr = make_raw_address(offset, phase);
3382 off[nst] = offset;
3383 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3384 phase->intcon(con1), T_INT);
3385 }
3386 }
3387
3388 // Insert second store first, then the first before the second.
3389 // Insert each one just before any overlapping non-constant stores.
3390 while (nst > 0) {
3391 Node* st1 = st[--nst];
3392 C->copy_node_notes_to(st1, old);
3393 st1 = phase->transform(st1);
3394 offset = off[nst];
3395 assert(offset >= header_size, "do not smash header");
3396 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
3397 guarantee(ins_idx != 0, "must re-insert constant store");
3398 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
3399 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
3400 set_req(--ins_idx, st1);
3401 else
3402 ins_req(ins_idx, st1);
3403 }
3404 }
3405
3406 if (PrintCompilation && WizardMode)
3407 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
3408 old_subword, old_long, new_int, new_long);
3409 if (C->log() != NULL)
3410 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
3411 old_subword, old_long, new_int, new_long);
3412
3413 // Clean up any remaining occurrences of zmem:
3414 remove_extra_zeroes();
3415 }
3416
3417 // Explore forward from in(start) to find the first fully initialized
3418 // word, and return its offset. Skip groups of subword stores which
3419 // together initialize full words. If in(start) is itself part of a
3420 // fully initialized word, return the offset of in(start). If there
3421 // are no following full-word stores, or if something is fishy, return
3422 // a negative value.
3423 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
3424 int int_map = 0;
3425 intptr_t int_map_off = 0;
3426 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
3427
3428 for (uint i = start, limit = req(); i < limit; i++) {
3429 Node* st = in(i);
3430
3431 intptr_t st_off = get_store_offset(st, phase);
3432 if (st_off < 0) break; // return conservative answer
3433
3434 int st_size = st->as_Store()->memory_size();
3435 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
3436 return st_off; // we found a complete word init
3437 }
3438
3439 // update the map:
3440
3441 intptr_t this_int_off = align_size_down(st_off, BytesPerInt);
3442 if (this_int_off != int_map_off) {
3443 // reset the map:
3444 int_map = 0;
3445 int_map_off = this_int_off;
3446 }
3447
3448 int subword_off = st_off - this_int_off;
3449 int_map |= right_n_bits(st_size) << subword_off;
3450 if ((int_map & FULL_MAP) == FULL_MAP) {
3451 return this_int_off; // we found a complete word init
3452 }
3453
3454 // Did this store hit or cross the word boundary?
3455 intptr_t next_int_off = align_size_down(st_off + st_size, BytesPerInt);
3456 if (next_int_off == this_int_off + BytesPerInt) {
3457 // We passed the current int, without fully initializing it.
3458 int_map_off = next_int_off;
3459 int_map >>= BytesPerInt;
3460 } else if (next_int_off > this_int_off + BytesPerInt) {
3461 // We passed the current and next int.
3462 return this_int_off + BytesPerInt;
3463 }
3464 }
3465
3466 return -1;
3467 }
3468
3469
3470 // Called when the associated AllocateNode is expanded into CFG.
3471 // At this point, we may perform additional optimizations.
3472 // Linearize the stores by ascending offset, to make memory
3473 // activity as coherent as possible.
3474 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
3475 intptr_t header_size,
3476 Node* size_in_bytes,
3477 PhaseGVN* phase) {
3478 assert(!is_complete(), "not already complete");
3479 assert(stores_are_sane(phase), "");
3480 assert(allocation() != NULL, "must be present");
3481
3482 remove_extra_zeroes();
3483
3484 if (ReduceFieldZeroing || ReduceBulkZeroing)
3485 // reduce instruction count for common initialization patterns
3486 coalesce_subword_stores(header_size, size_in_bytes, phase);
3487
3488 Node* zmem = zero_memory(); // initially zero memory state
3489 Node* inits = zmem; // accumulating a linearized chain of inits
3490 #ifdef ASSERT
3491 intptr_t first_offset = allocation()->minimum_header_size();
3492 intptr_t last_init_off = first_offset; // previous init offset
3493 intptr_t last_init_end = first_offset; // previous init offset+size
3494 intptr_t last_tile_end = first_offset; // previous tile offset+size
3495 #endif
3496 intptr_t zeroes_done = header_size;
3497
3498 bool do_zeroing = true; // we might give up if inits are very sparse
3499 int big_init_gaps = 0; // how many large gaps have we seen?
3500
3501 if (ZeroTLAB) do_zeroing = false;
3502 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
3503
3504 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3505 Node* st = in(i);
3506 intptr_t st_off = get_store_offset(st, phase);
3507 if (st_off < 0)
3508 break; // unknown junk in the inits
3509 if (st->in(MemNode::Memory) != zmem)
3510 break; // complicated store chains somehow in list
3511
3512 int st_size = st->as_Store()->memory_size();
3513 intptr_t next_init_off = st_off + st_size;
3514
3515 if (do_zeroing && zeroes_done < next_init_off) {
3516 // See if this store needs a zero before it or under it.
3517 intptr_t zeroes_needed = st_off;
3518
3519 if (st_size < BytesPerInt) {
3520 // Look for subword stores which only partially initialize words.
3521 // If we find some, we must lay down some word-level zeroes first,
3522 // underneath the subword stores.
3523 //
3524 // Examples:
3525 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
3526 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
3527 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
3528 //
3529 // Note: coalesce_subword_stores may have already done this,
3530 // if it was prompted by constant non-zero subword initializers.
3531 // But this case can still arise with non-constant stores.
3532
3533 intptr_t next_full_store = find_next_fullword_store(i, phase);
3534
3535 // In the examples above:
3536 // in(i) p q r s x y z
3537 // st_off 12 13 14 15 12 13 14
3538 // st_size 1 1 1 1 1 1 1
3539 // next_full_s. 12 16 16 16 16 16 16
3540 // z's_done 12 16 16 16 12 16 12
3541 // z's_needed 12 16 16 16 16 16 16
3542 // zsize 0 0 0 0 4 0 4
3543 if (next_full_store < 0) {
3544 // Conservative tack: Zero to end of current word.
3545 zeroes_needed = align_size_up(zeroes_needed, BytesPerInt);
3546 } else {
3547 // Zero to beginning of next fully initialized word.
3548 // Or, don't zero at all, if we are already in that word.
3549 assert(next_full_store >= zeroes_needed, "must go forward");
3550 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
3551 zeroes_needed = next_full_store;
3552 }
3553 }
3554
3555 if (zeroes_needed > zeroes_done) {
3556 intptr_t zsize = zeroes_needed - zeroes_done;
3557 // Do some incremental zeroing on rawmem, in parallel with inits.
3558 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3559 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3560 zeroes_done, zeroes_needed,
3561 phase);
3562 zeroes_done = zeroes_needed;
3563 if (zsize > Matcher::init_array_short_size && ++big_init_gaps > 2)
3564 do_zeroing = false; // leave the hole, next time
3565 }
3566 }
3567
3568 // Collect the store and move on:
3569 st->set_req(MemNode::Memory, inits);
3570 inits = st; // put it on the linearized chain
3571 set_req(i, zmem); // unhook from previous position
3572
3573 if (zeroes_done == st_off)
3574 zeroes_done = next_init_off;
3575
3576 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
3577
3578 #ifdef ASSERT
3579 // Various order invariants. Weaker than stores_are_sane because
3580 // a large constant tile can be filled in by smaller non-constant stores.
3581 assert(st_off >= last_init_off, "inits do not reverse");
3582 last_init_off = st_off;
3583 const Type* val = NULL;
3584 if (st_size >= BytesPerInt &&
3585 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
3586 (int)val->basic_type() < (int)T_OBJECT) {
3587 assert(st_off >= last_tile_end, "tiles do not overlap");
3588 assert(st_off >= last_init_end, "tiles do not overwrite inits");
3589 last_tile_end = MAX2(last_tile_end, next_init_off);
3590 } else {
3591 intptr_t st_tile_end = align_size_up(next_init_off, BytesPerLong);
3592 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
3593 assert(st_off >= last_init_end, "inits do not overlap");
3594 last_init_end = next_init_off; // it's a non-tile
3595 }
3596 #endif //ASSERT
3597 }
3598
3599 remove_extra_zeroes(); // clear out all the zmems left over
3600 add_req(inits);
3601
3602 if (!ZeroTLAB) {
3603 // If anything remains to be zeroed, zero it all now.
3604 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3605 // if it is the last unused 4 bytes of an instance, forget about it
3606 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
3607 if (zeroes_done + BytesPerLong >= size_limit) {
3608 assert(allocation() != NULL, "");
3609 if (allocation()->Opcode() == Op_Allocate) {
3610 Node* klass_node = allocation()->in(AllocateNode::KlassNode);
3611 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass();
3612 if (zeroes_done == k->layout_helper())
3613 zeroes_done = size_limit;
3614 }
3615 }
3616 if (zeroes_done < size_limit) {
3617 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3618 zeroes_done, size_in_bytes, phase);
3619 }
3620 }
3621
3622 set_complete(phase);
3623 return rawmem;
3624 }
3625
3626
3627 #ifdef ASSERT
3628 bool InitializeNode::stores_are_sane(PhaseTransform* phase) {
3629 if (is_complete())
3630 return true; // stores could be anything at this point
3631 assert(allocation() != NULL, "must be present");
3632 intptr_t last_off = allocation()->minimum_header_size();
3633 for (uint i = InitializeNode::RawStores; i < req(); i++) {
3634 Node* st = in(i);
3635 intptr_t st_off = get_store_offset(st, phase);
3636 if (st_off < 0) continue; // ignore dead garbage
3637 if (last_off > st_off) {
3638 tty->print_cr("*** bad store offset at %d: %d > %d", i, last_off, st_off);
3639 this->dump(2);
3640 assert(false, "ascending store offsets");
3641 return false;
3642 }
3643 last_off = st_off + st->as_Store()->memory_size();
3644 }
3645 return true;
3646 }
3647 #endif //ASSERT
3648
3649
3650
3651
3652 //============================MergeMemNode=====================================
3653 //
3654 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
3655 // contributing store or call operations. Each contributor provides the memory
3656 // state for a particular "alias type" (see Compile::alias_type). For example,
3657 // if a MergeMem has an input X for alias category #6, then any memory reference
3658 // to alias category #6 may use X as its memory state input, as an exact equivalent
3659 // to using the MergeMem as a whole.
3660 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
3661 //
3662 // (Here, the <N> notation gives the index of the relevant adr_type.)
3663 //
3664 // In one special case (and more cases in the future), alias categories overlap.
3665 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
3666 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
3667 // it is exactly equivalent to that state W:
3668 // MergeMem(<Bot>: W) <==> W
3669 //
3670 // Usually, the merge has more than one input. In that case, where inputs
3671 // overlap (i.e., one is Bot), the narrower alias type determines the memory
3672 // state for that type, and the wider alias type (Bot) fills in everywhere else:
3673 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
3674 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
3675 //
3676 // A merge can take a "wide" memory state as one of its narrow inputs.
3677 // This simply means that the merge observes out only the relevant parts of
3678 // the wide input. That is, wide memory states arriving at narrow merge inputs
3679 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
3680 //
3681 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
3682 // and that memory slices "leak through":
3683 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
3684 //
3685 // But, in such a cascade, repeated memory slices can "block the leak":
3686 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
3687 //
3688 // In the last example, Y is not part of the combined memory state of the
3689 // outermost MergeMem. The system must, of course, prevent unschedulable
3690 // memory states from arising, so you can be sure that the state Y is somehow
3691 // a precursor to state Y'.
3692 //
3693 //
3694 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
3695 // of each MergeMemNode array are exactly the numerical alias indexes, including
3696 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
3697 // Compile::alias_type (and kin) produce and manage these indexes.
3698 //
3699 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
3700 // (Note that this provides quick access to the top node inside MergeMem methods,
3701 // without the need to reach out via TLS to Compile::current.)
3702 //
3703 // As a consequence of what was just described, a MergeMem that represents a full
3704 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
3705 // containing all alias categories.
3706 //
3707 // MergeMem nodes never (?) have control inputs, so in(0) is NULL.
3708 //
3709 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
3710 // a memory state for the alias type <N>, or else the top node, meaning that
3711 // there is no particular input for that alias type. Note that the length of
3712 // a MergeMem is variable, and may be extended at any time to accommodate new
3713 // memory states at larger alias indexes. When merges grow, they are of course
3714 // filled with "top" in the unused in() positions.
3715 //
3716 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
3717 // (Top was chosen because it works smoothly with passes like GCM.)
3718 //
3719 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
3720 // the type of random VM bits like TLS references.) Since it is always the
3721 // first non-Bot memory slice, some low-level loops use it to initialize an
3722 // index variable: for (i = AliasIdxRaw; i < req(); i++).
3723 //
3724 //
3725 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
3726 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
3727 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
3728 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
3729 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
3730 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
3731 //
3732 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
3733 // really that different from the other memory inputs. An abbreviation called
3734 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
3735 //
3736 //
3737 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
3738 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
3739 // that "emerges though" the base memory will be marked as excluding the alias types
3740 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
3741 //
3742 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
3743 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
3744 //
3745 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
3746 // (It is currently unimplemented.) As you can see, the resulting merge is
3747 // actually a disjoint union of memory states, rather than an overlay.
3748 //
3749
3750 //------------------------------MergeMemNode-----------------------------------
3751 Node* MergeMemNode::make_empty_memory() {
3752 Node* empty_memory = (Node*) Compile::current()->top();
3753 assert(empty_memory->is_top(), "correct sentinel identity");
3754 return empty_memory;
3755 }
3756
3757 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
3758 init_class_id(Class_MergeMem);
3759 // all inputs are nullified in Node::Node(int)
3760 // set_input(0, NULL); // no control input
3761
3762 // Initialize the edges uniformly to top, for starters.
3763 Node* empty_mem = make_empty_memory();
3764 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
3765 init_req(i,empty_mem);
3766 }
3767 assert(empty_memory() == empty_mem, "");
3768
3769 if( new_base != NULL && new_base->is_MergeMem() ) {
3770 MergeMemNode* mdef = new_base->as_MergeMem();
3771 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
3772 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
3773 mms.set_memory(mms.memory2());
3774 }
3775 assert(base_memory() == mdef->base_memory(), "");
3776 } else {
3777 set_base_memory(new_base);
3778 }
3779 }
3780
3781 // Make a new, untransformed MergeMem with the same base as 'mem'.
3782 // If mem is itself a MergeMem, populate the result with the same edges.
3783 MergeMemNode* MergeMemNode::make(Compile* C, Node* mem) {
3784 return new(C, 1+Compile::AliasIdxRaw) MergeMemNode(mem);
3785 }
3786
3787 //------------------------------cmp--------------------------------------------
3788 uint MergeMemNode::hash() const { return NO_HASH; }
3789 uint MergeMemNode::cmp( const Node &n ) const {
3790 return (&n == this); // Always fail except on self
3791 }
3792
3793 //------------------------------Identity---------------------------------------
3794 Node* MergeMemNode::Identity(PhaseTransform *phase) {
3795 // Identity if this merge point does not record any interesting memory
3796 // disambiguations.
3797 Node* base_mem = base_memory();
3798 Node* empty_mem = empty_memory();
3799 if (base_mem != empty_mem) { // Memory path is not dead?
3800 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3801 Node* mem = in(i);
3802 if (mem != empty_mem && mem != base_mem) {
3803 return this; // Many memory splits; no change
3804 }
3805 }
3806 }
3807 return base_mem; // No memory splits; ID on the one true input
3808 }
3809
3810 //------------------------------Ideal------------------------------------------
3811 // This method is invoked recursively on chains of MergeMem nodes
3812 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3813 // Remove chain'd MergeMems
3814 //
3815 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
3816 // relative to the "in(Bot)". Since we are patching both at the same time,
3817 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
3818 // but rewrite each "in(i)" relative to the new "in(Bot)".
3819 Node *progress = NULL;
3820
3821
3822 Node* old_base = base_memory();
3823 Node* empty_mem = empty_memory();
3824 if (old_base == empty_mem)
3825 return NULL; // Dead memory path.
3826
3827 MergeMemNode* old_mbase;
3828 if (old_base != NULL && old_base->is_MergeMem())
3829 old_mbase = old_base->as_MergeMem();
3830 else
3831 old_mbase = NULL;
3832 Node* new_base = old_base;
3833
3834 // simplify stacked MergeMems in base memory
3835 if (old_mbase) new_base = old_mbase->base_memory();
3836
3837 // the base memory might contribute new slices beyond my req()
3838 if (old_mbase) grow_to_match(old_mbase);
3839
3840 // Look carefully at the base node if it is a phi.
3841 PhiNode* phi_base;
3842 if (new_base != NULL && new_base->is_Phi())
3843 phi_base = new_base->as_Phi();
3844 else
3845 phi_base = NULL;
3846
3847 Node* phi_reg = NULL;
3848 uint phi_len = (uint)-1;
3849 if (phi_base != NULL && !phi_base->is_copy()) {
3850 // do not examine phi if degraded to a copy
3851 phi_reg = phi_base->region();
3852 phi_len = phi_base->req();
3853 // see if the phi is unfinished
3854 for (uint i = 1; i < phi_len; i++) {
3855 if (phi_base->in(i) == NULL) {
3856 // incomplete phi; do not look at it yet!
3857 phi_reg = NULL;
3858 phi_len = (uint)-1;
3859 break;
3860 }
3861 }
3862 }
3863
3864 // Note: We do not call verify_sparse on entry, because inputs
3865 // can normalize to the base_memory via subsume_node or similar
3866 // mechanisms. This method repairs that damage.
3867
3868 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
3869
3870 // Look at each slice.
3871 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3872 Node* old_in = in(i);
3873 // calculate the old memory value
3874 Node* old_mem = old_in;
3875 if (old_mem == empty_mem) old_mem = old_base;
3876 assert(old_mem == memory_at(i), "");
3877
3878 // maybe update (reslice) the old memory value
3879
3880 // simplify stacked MergeMems
3881 Node* new_mem = old_mem;
3882 MergeMemNode* old_mmem;
3883 if (old_mem != NULL && old_mem->is_MergeMem())
3884 old_mmem = old_mem->as_MergeMem();
3885 else
3886 old_mmem = NULL;
3887 if (old_mmem == this) {
3888 // This can happen if loops break up and safepoints disappear.
3889 // A merge of BotPtr (default) with a RawPtr memory derived from a
3890 // safepoint can be rewritten to a merge of the same BotPtr with
3891 // the BotPtr phi coming into the loop. If that phi disappears
3892 // also, we can end up with a self-loop of the mergemem.
3893 // In general, if loops degenerate and memory effects disappear,
3894 // a mergemem can be left looking at itself. This simply means
3895 // that the mergemem's default should be used, since there is
3896 // no longer any apparent effect on this slice.
3897 // Note: If a memory slice is a MergeMem cycle, it is unreachable
3898 // from start. Update the input to TOP.
3899 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
3900 }
3901 else if (old_mmem != NULL) {
3902 new_mem = old_mmem->memory_at(i);
3903 }
3904 // else preceding memory was not a MergeMem
3905
3906 // replace equivalent phis (unfortunately, they do not GVN together)
3907 if (new_mem != NULL && new_mem != new_base &&
3908 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) {
3909 if (new_mem->is_Phi()) {
3910 PhiNode* phi_mem = new_mem->as_Phi();
3911 for (uint i = 1; i < phi_len; i++) {
3912 if (phi_base->in(i) != phi_mem->in(i)) {
3913 phi_mem = NULL;
3914 break;
3915 }
3916 }
3917 if (phi_mem != NULL) {
3918 // equivalent phi nodes; revert to the def
3919 new_mem = new_base;
3920 }
3921 }
3922 }
3923
3924 // maybe store down a new value
3925 Node* new_in = new_mem;
3926 if (new_in == new_base) new_in = empty_mem;
3927
3928 if (new_in != old_in) {
3929 // Warning: Do not combine this "if" with the previous "if"
3930 // A memory slice might have be be rewritten even if it is semantically
3931 // unchanged, if the base_memory value has changed.
3932 set_req(i, new_in);
3933 progress = this; // Report progress
3934 }
3935 }
3936
3937 if (new_base != old_base) {
3938 set_req(Compile::AliasIdxBot, new_base);
3939 // Don't use set_base_memory(new_base), because we need to update du.
3940 assert(base_memory() == new_base, "");
3941 progress = this;
3942 }
3943
3944 if( base_memory() == this ) {
3945 // a self cycle indicates this memory path is dead
3946 set_req(Compile::AliasIdxBot, empty_mem);
3947 }
3948
3949 // Resolve external cycles by calling Ideal on a MergeMem base_memory
3950 // Recursion must occur after the self cycle check above
3951 if( base_memory()->is_MergeMem() ) {
3952 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
3953 Node *m = phase->transform(new_mbase); // Rollup any cycles
3954 if( m != NULL && (m->is_top() ||
3955 m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem) ) {
3956 // propagate rollup of dead cycle to self
3957 set_req(Compile::AliasIdxBot, empty_mem);
3958 }
3959 }
3960
3961 if( base_memory() == empty_mem ) {
3962 progress = this;
3963 // Cut inputs during Parse phase only.
3964 // During Optimize phase a dead MergeMem node will be subsumed by Top.
3965 if( !can_reshape ) {
3966 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3967 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
3968 }
3969 }
3970 }
3971
3972 if( !progress && base_memory()->is_Phi() && can_reshape ) {
3973 // Check if PhiNode::Ideal's "Split phis through memory merges"
3974 // transform should be attempted. Look for this->phi->this cycle.
3975 uint merge_width = req();
3976 if (merge_width > Compile::AliasIdxRaw) {
3977 PhiNode* phi = base_memory()->as_Phi();
3978 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
3979 if (phi->in(i) == this) {
3980 phase->is_IterGVN()->_worklist.push(phi);
3981 break;
3982 }
3983 }
3984 }
3985 }
3986
3987 assert(progress || verify_sparse(), "please, no dups of base");
3988 return progress;
3989 }
3990
3991 //-------------------------set_base_memory-------------------------------------
3992 void MergeMemNode::set_base_memory(Node *new_base) {
3993 Node* empty_mem = empty_memory();
3994 set_req(Compile::AliasIdxBot, new_base);
3995 assert(memory_at(req()) == new_base, "must set default memory");
3996 // Clear out other occurrences of new_base:
3997 if (new_base != empty_mem) {
3998 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3999 if (in(i) == new_base) set_req(i, empty_mem);
4000 }
4001 }
4002 }
4003
4004 //------------------------------out_RegMask------------------------------------
4005 const RegMask &MergeMemNode::out_RegMask() const {
4006 return RegMask::Empty;
4007 }
4008
4009 //------------------------------dump_spec--------------------------------------
4010 #ifndef PRODUCT
4011 void MergeMemNode::dump_spec(outputStream *st) const {
4012 st->print(" {");
4013 Node* base_mem = base_memory();
4014 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
4015 Node* mem = memory_at(i);
4016 if (mem == base_mem) { st->print(" -"); continue; }
4017 st->print( " N%d:", mem->_idx );
4018 Compile::current()->get_adr_type(i)->dump_on(st);
4019 }
4020 st->print(" }");
4021 }
4022 #endif // !PRODUCT
4023
4024
4025 #ifdef ASSERT
4026 static bool might_be_same(Node* a, Node* b) {
4027 if (a == b) return true;
4028 if (!(a->is_Phi() || b->is_Phi())) return false;
4029 // phis shift around during optimization
4030 return true; // pretty stupid...
4031 }
4032
4033 // verify a narrow slice (either incoming or outgoing)
4034 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
4035 if (!VerifyAliases) return; // don't bother to verify unless requested
4036 if (is_error_reported()) return; // muzzle asserts when debugging an error
4037 if (Node::in_dump()) return; // muzzle asserts when printing
4038 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
4039 assert(n != NULL, "");
4040 // Elide intervening MergeMem's
4041 while (n->is_MergeMem()) {
4042 n = n->as_MergeMem()->memory_at(alias_idx);
4043 }
4044 Compile* C = Compile::current();
4045 const TypePtr* n_adr_type = n->adr_type();
4046 if (n == m->empty_memory()) {
4047 // Implicit copy of base_memory()
4048 } else if (n_adr_type != TypePtr::BOTTOM) {
4049 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type");
4050 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
4051 } else {
4052 // A few places like make_runtime_call "know" that VM calls are narrow,
4053 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
4054 bool expected_wide_mem = false;
4055 if (n == m->base_memory()) {
4056 expected_wide_mem = true;
4057 } else if (alias_idx == Compile::AliasIdxRaw ||
4058 n == m->memory_at(Compile::AliasIdxRaw)) {
4059 expected_wide_mem = true;
4060 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
4061 // memory can "leak through" calls on channels that
4062 // are write-once. Allow this also.
4063 expected_wide_mem = true;
4064 }
4065 assert(expected_wide_mem, "expected narrow slice replacement");
4066 }
4067 }
4068 #else // !ASSERT
4069 #define verify_memory_slice(m,i,n) (0) // PRODUCT version is no-op
4070 #endif
4071
4072
4073 //-----------------------------memory_at---------------------------------------
4074 Node* MergeMemNode::memory_at(uint alias_idx) const {
4075 assert(alias_idx >= Compile::AliasIdxRaw ||
4076 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0,
4077 "must avoid base_memory and AliasIdxTop");
4078
4079 // Otherwise, it is a narrow slice.
4080 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
4081 Compile *C = Compile::current();
4082 if (is_empty_memory(n)) {
4083 // the array is sparse; empty slots are the "top" node
4084 n = base_memory();
4085 assert(Node::in_dump()
4086 || n == NULL || n->bottom_type() == Type::TOP
4087 || n->adr_type() == NULL // address is TOP
4088 || n->adr_type() == TypePtr::BOTTOM
4089 || n->adr_type() == TypeRawPtr::BOTTOM
4090 || Compile::current()->AliasLevel() == 0,
4091 "must be a wide memory");
4092 // AliasLevel == 0 if we are organizing the memory states manually.
4093 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
4094 } else {
4095 // make sure the stored slice is sane
4096 #ifdef ASSERT
4097 if (is_error_reported() || Node::in_dump()) {
4098 } else if (might_be_same(n, base_memory())) {
4099 // Give it a pass: It is a mostly harmless repetition of the base.
4100 // This can arise normally from node subsumption during optimization.
4101 } else {
4102 verify_memory_slice(this, alias_idx, n);
4103 }
4104 #endif
4105 }
4106 return n;
4107 }
4108
4109 //---------------------------set_memory_at-------------------------------------
4110 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
4111 verify_memory_slice(this, alias_idx, n);
4112 Node* empty_mem = empty_memory();
4113 if (n == base_memory()) n = empty_mem; // collapse default
4114 uint need_req = alias_idx+1;
4115 if (req() < need_req) {
4116 if (n == empty_mem) return; // already the default, so do not grow me
4117 // grow the sparse array
4118 do {
4119 add_req(empty_mem);
4120 } while (req() < need_req);
4121 }
4122 set_req( alias_idx, n );
4123 }
4124
4125
4126
4127 //--------------------------iteration_setup------------------------------------
4128 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
4129 if (other != NULL) {
4130 grow_to_match(other);
4131 // invariant: the finite support of mm2 is within mm->req()
4132 #ifdef ASSERT
4133 for (uint i = req(); i < other->req(); i++) {
4134 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
4135 }
4136 #endif
4137 }
4138 // Replace spurious copies of base_memory by top.
4139 Node* base_mem = base_memory();
4140 if (base_mem != NULL && !base_mem->is_top()) {
4141 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
4142 if (in(i) == base_mem)
4143 set_req(i, empty_memory());
4144 }
4145 }
4146 }
4147
4148 //---------------------------grow_to_match-------------------------------------
4149 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
4150 Node* empty_mem = empty_memory();
4151 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
4152 // look for the finite support of the other memory
4153 for (uint i = other->req(); --i >= req(); ) {
4154 if (other->in(i) != empty_mem) {
4155 uint new_len = i+1;
4156 while (req() < new_len) add_req(empty_mem);
4157 break;
4158 }
4159 }
4160 }
4161
4162 //---------------------------verify_sparse-------------------------------------
4163 #ifndef PRODUCT
4164 bool MergeMemNode::verify_sparse() const {
4165 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
4166 Node* base_mem = base_memory();
4167 // The following can happen in degenerate cases, since empty==top.
4168 if (is_empty_memory(base_mem)) return true;
4169 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4170 assert(in(i) != NULL, "sane slice");
4171 if (in(i) == base_mem) return false; // should have been the sentinel value!
4172 }
4173 return true;
4174 }
4175
4176 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
4177 Node* n;
4178 n = mm->in(idx);
4179 if (mem == n) return true; // might be empty_memory()
4180 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
4181 if (mem == n) return true;
4182 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) {
4183 if (mem == n) return true;
4184 if (n == NULL) break;
4185 }
4186 return false;
4187 }
4188 #endif // !PRODUCT