1 /*
2 * Copyright (c) 1997, 2010, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/systemDictionary.hpp"
27 #include "compiler/compileLog.hpp"
28 #include "memory/allocation.inline.hpp"
29 #include "oops/objArrayKlass.hpp"
30 #include "opto/addnode.hpp"
31 #include "opto/cfgnode.hpp"
32 #include "opto/compile.hpp"
33 #include "opto/connode.hpp"
34 #include "opto/loopnode.hpp"
35 #include "opto/machnode.hpp"
36 #include "opto/matcher.hpp"
37 #include "opto/memnode.hpp"
38 #include "opto/mulnode.hpp"
39 #include "opto/phaseX.hpp"
40 #include "opto/regmask.hpp"
41
42 // Portions of code courtesy of Clifford Click
43
44 // Optimization - Graph Style
45
46 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st);
47
48 //=============================================================================
49 uint MemNode::size_of() const { return sizeof(*this); }
50
51 const TypePtr *MemNode::adr_type() const {
52 Node* adr = in(Address);
53 const TypePtr* cross_check = NULL;
54 DEBUG_ONLY(cross_check = _adr_type);
55 return calculate_adr_type(adr->bottom_type(), cross_check);
56 }
57
58 #ifndef PRODUCT
59 void MemNode::dump_spec(outputStream *st) const {
60 if (in(Address) == NULL) return; // node is dead
61 #ifndef ASSERT
62 // fake the missing field
63 const TypePtr* _adr_type = NULL;
64 if (in(Address) != NULL)
65 _adr_type = in(Address)->bottom_type()->isa_ptr();
66 #endif
67 dump_adr_type(this, _adr_type, st);
68
69 Compile* C = Compile::current();
70 if( C->alias_type(_adr_type)->is_volatile() )
71 st->print(" Volatile!");
72 }
73
74 void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) {
75 st->print(" @");
76 if (adr_type == NULL) {
77 st->print("NULL");
78 } else {
79 adr_type->dump_on(st);
80 Compile* C = Compile::current();
81 Compile::AliasType* atp = NULL;
82 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type);
83 if (atp == NULL)
84 st->print(", idx=?\?;");
85 else if (atp->index() == Compile::AliasIdxBot)
86 st->print(", idx=Bot;");
87 else if (atp->index() == Compile::AliasIdxTop)
88 st->print(", idx=Top;");
89 else if (atp->index() == Compile::AliasIdxRaw)
90 st->print(", idx=Raw;");
91 else {
92 ciField* field = atp->field();
93 if (field) {
94 st->print(", name=");
95 field->print_name_on(st);
96 }
97 st->print(", idx=%d;", atp->index());
98 }
99 }
100 }
101
102 extern void print_alias_types();
103
104 #endif
105
106 Node *MemNode::optimize_simple_memory_chain(Node *mchain, const TypePtr *t_adr, PhaseGVN *phase) {
107 const TypeOopPtr *tinst = t_adr->isa_oopptr();
108 if (tinst == NULL || !tinst->is_known_instance_field())
109 return mchain; // don't try to optimize non-instance types
110 uint instance_id = tinst->instance_id();
111 Node *start_mem = phase->C->start()->proj_out(TypeFunc::Memory);
112 Node *prev = NULL;
113 Node *result = mchain;
114 while (prev != result) {
115 prev = result;
116 if (result == start_mem)
117 break; // hit one of our sentinels
118 // skip over a call which does not affect this memory slice
119 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {
120 Node *proj_in = result->in(0);
121 if (proj_in->is_Allocate() && proj_in->_idx == instance_id) {
122 break; // hit one of our sentinels
123 } else if (proj_in->is_Call()) {
124 CallNode *call = proj_in->as_Call();
125 if (!call->may_modify(t_adr, phase)) {
126 result = call->in(TypeFunc::Memory);
127 }
128 } else if (proj_in->is_Initialize()) {
129 AllocateNode* alloc = proj_in->as_Initialize()->allocation();
130 // Stop if this is the initialization for the object instance which
131 // which contains this memory slice, otherwise skip over it.
132 if (alloc != NULL && alloc->_idx != instance_id) {
133 result = proj_in->in(TypeFunc::Memory);
134 }
135 } else if (proj_in->is_MemBar()) {
136 result = proj_in->in(TypeFunc::Memory);
137 } else {
138 assert(false, "unexpected projection");
139 }
140 } else if (result->is_ClearArray()) {
141 if (!ClearArrayNode::step_through(&result, instance_id, phase)) {
142 // Can not bypass initialization of the instance
143 // we are looking for.
144 break;
145 }
146 // Otherwise skip it (the call updated 'result' value).
147 } else if (result->is_MergeMem()) {
148 result = step_through_mergemem(phase, result->as_MergeMem(), t_adr, NULL, tty);
149 }
150 }
151 return result;
152 }
153
154 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, PhaseGVN *phase) {
155 const TypeOopPtr *t_oop = t_adr->isa_oopptr();
156 bool is_instance = (t_oop != NULL) && t_oop->is_known_instance_field();
157 PhaseIterGVN *igvn = phase->is_IterGVN();
158 Node *result = mchain;
159 result = optimize_simple_memory_chain(result, t_adr, phase);
160 if (is_instance && igvn != NULL && result->is_Phi()) {
161 PhiNode *mphi = result->as_Phi();
162 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
163 const TypePtr *t = mphi->adr_type();
164 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
165 t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
166 t->is_oopptr()->cast_to_exactness(true)
167 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
168 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop) {
169 // clone the Phi with our address type
170 result = mphi->split_out_instance(t_adr, igvn);
171 } else {
172 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain");
173 }
174 }
175 return result;
176 }
177
178 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) {
179 uint alias_idx = phase->C->get_alias_index(tp);
180 Node *mem = mmem;
181 #ifdef ASSERT
182 {
183 // Check that current type is consistent with the alias index used during graph construction
184 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
185 bool consistent = adr_check == NULL || adr_check->empty() ||
186 phase->C->must_alias(adr_check, alias_idx );
187 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
188 if( !consistent && adr_check != NULL && !adr_check->empty() &&
189 tp->isa_aryptr() && tp->offset() == Type::OffsetBot &&
190 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot &&
191 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() ||
192 adr_check->offset() == oopDesc::klass_offset_in_bytes() ||
193 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) {
194 // don't assert if it is dead code.
195 consistent = true;
196 }
197 if( !consistent ) {
198 st->print("alias_idx==%d, adr_check==", alias_idx);
199 if( adr_check == NULL ) {
200 st->print("NULL");
201 } else {
202 adr_check->dump();
203 }
204 st->cr();
205 print_alias_types();
206 assert(consistent, "adr_check must match alias idx");
207 }
208 }
209 #endif
210 // TypeInstPtr::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 *tinst = tp->isa_oopptr();
214 if( tp->base() != Type::AnyPtr &&
215 !(tinst &&
216 tinst->klass()->is_java_lang_Object() &&
217 tinst->offset() == Type::OffsetBot) ) {
218 // compress paths and change unreachable cycles to TOP
219 // If not, we can update the input infinitely along a MergeMem cycle
220 // Equivalent code in PhiNode::Ideal
221 Node* m = phase->transform(mmem);
222 // If transformed to a MergeMem, get the desired slice
223 // Otherwise the returned node represents memory for every slice
224 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
225 // Update input if it is progress over what we have now
226 }
227 return mem;
228 }
229
230 //--------------------------Ideal_common---------------------------------------
231 // Look for degenerate control and memory inputs. Bypass MergeMem inputs.
232 // Unhook non-raw memories from complete (macro-expanded) initializations.
233 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
234 // If our control input is a dead region, kill all below the region
235 Node *ctl = in(MemNode::Control);
236 if (ctl && remove_dead_region(phase, can_reshape))
237 return this;
238 ctl = in(MemNode::Control);
239 // Don't bother trying to transform a dead node
240 if( ctl && ctl->is_top() ) return NodeSentinel;
241
242 PhaseIterGVN *igvn = phase->is_IterGVN();
243 // Wait if control on the worklist.
244 if (ctl && can_reshape && igvn != NULL) {
245 Node* bol = NULL;
246 Node* cmp = NULL;
247 if (ctl->in(0)->is_If()) {
248 assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity");
249 bol = ctl->in(0)->in(1);
250 if (bol->is_Bool())
251 cmp = ctl->in(0)->in(1)->in(1);
252 }
253 if (igvn->_worklist.member(ctl) ||
254 (bol != NULL && igvn->_worklist.member(bol)) ||
255 (cmp != NULL && igvn->_worklist.member(cmp)) ) {
256 // This control path may be dead.
257 // Delay this memory node transformation until the control is processed.
258 phase->is_IterGVN()->_worklist.push(this);
259 return NodeSentinel; // caller will return NULL
260 }
261 }
262 // Ignore if memory is dead, or self-loop
263 Node *mem = in(MemNode::Memory);
264 if( phase->type( mem ) == Type::TOP ) return NodeSentinel; // caller will return NULL
265 assert( mem != this, "dead loop in MemNode::Ideal" );
266
267 Node *address = in(MemNode::Address);
268 const Type *t_adr = phase->type( address );
269 if( t_adr == Type::TOP ) return NodeSentinel; // caller will return NULL
270
271 if( can_reshape && igvn != NULL &&
272 (igvn->_worklist.member(address) || phase->type(address) != adr_type()) ) {
273 // The address's base and type may change when the address is processed.
274 // Delay this mem node transformation until the address is processed.
275 phase->is_IterGVN()->_worklist.push(this);
276 return NodeSentinel; // caller will return NULL
277 }
278
279 // Do NOT remove or optimize the next lines: ensure a new alias index
280 // is allocated for an oop pointer type before Escape Analysis.
281 // Note: C++ will not remove it since the call has side effect.
282 if ( t_adr->isa_oopptr() ) {
283 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr());
284 }
285
286 #ifdef ASSERT
287 Node* base = NULL;
288 if (address->is_AddP())
289 base = address->in(AddPNode::Base);
290 assert(base == NULL || t_adr->isa_rawptr() ||
291 !phase->type(base)->higher_equal(TypePtr::NULL_PTR), "NULL+offs not RAW address?");
292 #endif
293
294 // Avoid independent memory operations
295 Node* old_mem = mem;
296
297 // The code which unhooks non-raw memories from complete (macro-expanded)
298 // initializations was removed. After macro-expansion all stores catched
299 // by Initialize node became raw stores and there is no information
300 // which memory slices they modify. So it is unsafe to move any memory
301 // operation above these stores. Also in most cases hooked non-raw memories
302 // were already unhooked by using information from detect_ptr_independence()
303 // and find_previous_store().
304
305 if (mem->is_MergeMem()) {
306 MergeMemNode* mmem = mem->as_MergeMem();
307 const TypePtr *tp = t_adr->is_ptr();
308
309 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
310 }
311
312 if (mem != old_mem) {
313 set_req(MemNode::Memory, mem);
314 if (phase->type( mem ) == Type::TOP) return NodeSentinel;
315 return this;
316 }
317
318 // let the subclass continue analyzing...
319 return NULL;
320 }
321
322 // Helper function for proving some simple control dominations.
323 // Attempt to prove that all control inputs of 'dom' dominate 'sub'.
324 // Already assumes that 'dom' is available at 'sub', and that 'sub'
325 // is not a constant (dominated by the method's StartNode).
326 // Used by MemNode::find_previous_store to prove that the
327 // control input of a memory operation predates (dominates)
328 // an allocation it wants to look past.
329 bool MemNode::all_controls_dominate(Node* dom, Node* sub) {
330 if (dom == NULL || dom->is_top() || sub == NULL || sub->is_top())
331 return false; // Conservative answer for dead code
332
333 // Check 'dom'. Skip Proj and CatchProj nodes.
334 dom = dom->find_exact_control(dom);
335 if (dom == NULL || dom->is_top())
336 return false; // Conservative answer for dead code
337
338 if (dom == sub) {
339 // For the case when, for example, 'sub' is Initialize and the original
340 // 'dom' is Proj node of the 'sub'.
341 return false;
342 }
343
344 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub)
345 return true;
346
347 // 'dom' dominates 'sub' if its control edge and control edges
348 // of all its inputs dominate or equal to sub's control edge.
349
350 // Currently 'sub' is either Allocate, Initialize or Start nodes.
351 // Or Region for the check in LoadNode::Ideal();
352 // 'sub' should have sub->in(0) != NULL.
353 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() ||
354 sub->is_Region(), "expecting only these nodes");
355
356 // Get control edge of 'sub'.
357 Node* orig_sub = sub;
358 sub = sub->find_exact_control(sub->in(0));
359 if (sub == NULL || sub->is_top())
360 return false; // Conservative answer for dead code
361
362 assert(sub->is_CFG(), "expecting control");
363
364 if (sub == dom)
365 return true;
366
367 if (sub->is_Start() || sub->is_Root())
368 return false;
369
370 {
371 // Check all control edges of 'dom'.
372
373 ResourceMark rm;
374 Arena* arena = Thread::current()->resource_area();
375 Node_List nlist(arena);
376 Unique_Node_List dom_list(arena);
377
378 dom_list.push(dom);
379 bool only_dominating_controls = false;
380
381 for (uint next = 0; next < dom_list.size(); next++) {
382 Node* n = dom_list.at(next);
383 if (n == orig_sub)
384 return false; // One of dom's inputs dominated by sub.
385 if (!n->is_CFG() && n->pinned()) {
386 // Check only own control edge for pinned non-control nodes.
387 n = n->find_exact_control(n->in(0));
388 if (n == NULL || n->is_top())
389 return false; // Conservative answer for dead code
390 assert(n->is_CFG(), "expecting control");
391 dom_list.push(n);
392 } else if (n->is_Con() || n->is_Start() || n->is_Root()) {
393 only_dominating_controls = true;
394 } else if (n->is_CFG()) {
395 if (n->dominates(sub, nlist))
396 only_dominating_controls = true;
397 else
398 return false;
399 } else {
400 // First, own control edge.
401 Node* m = n->find_exact_control(n->in(0));
402 if (m != NULL) {
403 if (m->is_top())
404 return false; // Conservative answer for dead code
405 dom_list.push(m);
406 }
407 // Now, the rest of edges.
408 uint cnt = n->req();
409 for (uint i = 1; i < cnt; i++) {
410 m = n->find_exact_control(n->in(i));
411 if (m == NULL || m->is_top())
412 continue;
413 dom_list.push(m);
414 }
415 }
416 }
417 return only_dominating_controls;
418 }
419 }
420
421 //---------------------detect_ptr_independence---------------------------------
422 // Used by MemNode::find_previous_store to prove that two base
423 // pointers are never equal.
424 // The pointers are accompanied by their associated allocations,
425 // if any, which have been previously discovered by the caller.
426 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
427 Node* p2, AllocateNode* a2,
428 PhaseTransform* phase) {
429 // Attempt to prove that these two pointers cannot be aliased.
430 // They may both manifestly be allocations, and they should differ.
431 // Or, if they are not both allocations, they can be distinct constants.
432 // Otherwise, one is an allocation and the other a pre-existing value.
433 if (a1 == NULL && a2 == NULL) { // neither an allocation
434 return (p1 != p2) && p1->is_Con() && p2->is_Con();
435 } else if (a1 != NULL && a2 != NULL) { // both allocations
436 return (a1 != a2);
437 } else if (a1 != NULL) { // one allocation a1
438 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.)
439 return all_controls_dominate(p2, a1);
440 } else { //(a2 != NULL) // one allocation a2
441 return all_controls_dominate(p1, a2);
442 }
443 return false;
444 }
445
446
447 // The logic for reordering loads and stores uses four steps:
448 // (a) Walk carefully past stores and initializations which we
449 // can prove are independent of this load.
450 // (b) Observe that the next memory state makes an exact match
451 // with self (load or store), and locate the relevant store.
452 // (c) Ensure that, if we were to wire self directly to the store,
453 // the optimizer would fold it up somehow.
454 // (d) Do the rewiring, and return, depending on some other part of
455 // the optimizer to fold up the load.
456 // This routine handles steps (a) and (b). Steps (c) and (d) are
457 // specific to loads and stores, so they are handled by the callers.
458 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.)
459 //
460 Node* MemNode::find_previous_store(PhaseTransform* phase) {
461 Node* ctrl = in(MemNode::Control);
462 Node* adr = in(MemNode::Address);
463 intptr_t offset = 0;
464 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
465 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase);
466
467 if (offset == Type::OffsetBot)
468 return NULL; // cannot unalias unless there are precise offsets
469
470 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr();
471
472 intptr_t size_in_bytes = memory_size();
473
474 Node* mem = in(MemNode::Memory); // start searching here...
475
476 int cnt = 50; // Cycle limiter
477 for (;;) { // While we can dance past unrelated stores...
478 if (--cnt < 0) break; // Caught in cycle or a complicated dance?
479
480 if (mem->is_Store()) {
481 Node* st_adr = mem->in(MemNode::Address);
482 intptr_t st_offset = 0;
483 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
484 if (st_base == NULL)
485 break; // inscrutable pointer
486 if (st_offset != offset && st_offset != Type::OffsetBot) {
487 const int MAX_STORE = BytesPerLong;
488 if (st_offset >= offset + size_in_bytes ||
489 st_offset <= offset - MAX_STORE ||
490 st_offset <= offset - mem->as_Store()->memory_size()) {
491 // Success: The offsets are provably independent.
492 // (You may ask, why not just test st_offset != offset and be done?
493 // The answer is that stores of different sizes can co-exist
494 // in the same sequence of RawMem effects. We sometimes initialize
495 // a whole 'tile' of array elements with a single jint or jlong.)
496 mem = mem->in(MemNode::Memory);
497 continue; // (a) advance through independent store memory
498 }
499 }
500 if (st_base != base &&
501 detect_ptr_independence(base, alloc,
502 st_base,
503 AllocateNode::Ideal_allocation(st_base, phase),
504 phase)) {
505 // Success: The bases are provably independent.
506 mem = mem->in(MemNode::Memory);
507 continue; // (a) advance through independent store memory
508 }
509
510 // (b) At this point, if the bases or offsets do not agree, we lose,
511 // since we have not managed to prove 'this' and 'mem' independent.
512 if (st_base == base && st_offset == offset) {
513 return mem; // let caller handle steps (c), (d)
514 }
515
516 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
517 InitializeNode* st_init = mem->in(0)->as_Initialize();
518 AllocateNode* st_alloc = st_init->allocation();
519 if (st_alloc == NULL)
520 break; // something degenerated
521 bool known_identical = false;
522 bool known_independent = false;
523 if (alloc == st_alloc)
524 known_identical = true;
525 else if (alloc != NULL)
526 known_independent = true;
527 else if (all_controls_dominate(this, st_alloc))
528 known_independent = true;
529
530 if (known_independent) {
531 // The bases are provably independent: Either they are
532 // manifestly distinct allocations, or else the control
533 // of this load dominates the store's allocation.
534 int alias_idx = phase->C->get_alias_index(adr_type());
535 if (alias_idx == Compile::AliasIdxRaw) {
536 mem = st_alloc->in(TypeFunc::Memory);
537 } else {
538 mem = st_init->memory(alias_idx);
539 }
540 continue; // (a) advance through independent store memory
541 }
542
543 // (b) at this point, if we are not looking at a store initializing
544 // the same allocation we are loading from, we lose.
545 if (known_identical) {
546 // From caller, can_see_stored_value will consult find_captured_store.
547 return mem; // let caller handle steps (c), (d)
548 }
549
550 } else if (addr_t != NULL && addr_t->is_known_instance_field()) {
551 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
552 if (mem->is_Proj() && mem->in(0)->is_Call()) {
553 CallNode *call = mem->in(0)->as_Call();
554 if (!call->may_modify(addr_t, phase)) {
555 mem = call->in(TypeFunc::Memory);
556 continue; // (a) advance through independent call memory
557 }
558 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) {
559 mem = mem->in(0)->in(TypeFunc::Memory);
560 continue; // (a) advance through independent MemBar memory
561 } else if (mem->is_ClearArray()) {
562 if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) {
563 // (the call updated 'mem' value)
564 continue; // (a) advance through independent allocation memory
565 } else {
566 // Can not bypass initialization of the instance
567 // we are looking for.
568 return mem;
569 }
570 } else if (mem->is_MergeMem()) {
571 int alias_idx = phase->C->get_alias_index(adr_type());
572 mem = mem->as_MergeMem()->memory_at(alias_idx);
573 continue; // (a) advance through independent MergeMem memory
574 }
575 }
576
577 // Unless there is an explicit 'continue', we must bail out here,
578 // because 'mem' is an inscrutable memory state (e.g., a call).
579 break;
580 }
581
582 return NULL; // bail out
583 }
584
585 //----------------------calculate_adr_type-------------------------------------
586 // Helper function. Notices when the given type of address hits top or bottom.
587 // Also, asserts a cross-check of the type against the expected address type.
588 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
589 if (t == Type::TOP) return NULL; // does not touch memory any more?
590 #ifdef PRODUCT
591 cross_check = NULL;
592 #else
593 if (!VerifyAliases || is_error_reported() || Node::in_dump()) cross_check = NULL;
594 #endif
595 const TypePtr* tp = t->isa_ptr();
596 if (tp == NULL) {
597 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
598 return TypePtr::BOTTOM; // touches lots of memory
599 } else {
600 #ifdef ASSERT
601 // %%%% [phh] We don't check the alias index if cross_check is
602 // TypeRawPtr::BOTTOM. Needs to be investigated.
603 if (cross_check != NULL &&
604 cross_check != TypePtr::BOTTOM &&
605 cross_check != TypeRawPtr::BOTTOM) {
606 // Recheck the alias index, to see if it has changed (due to a bug).
607 Compile* C = Compile::current();
608 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
609 "must stay in the original alias category");
610 // The type of the address must be contained in the adr_type,
611 // disregarding "null"-ness.
612 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
613 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
614 assert(cross_check->meet(tp_notnull) == cross_check,
615 "real address must not escape from expected memory type");
616 }
617 #endif
618 return tp;
619 }
620 }
621
622 //------------------------adr_phi_is_loop_invariant----------------------------
623 // A helper function for Ideal_DU_postCCP to check if a Phi in a counted
624 // loop is loop invariant. Make a quick traversal of Phi and associated
625 // CastPP nodes, looking to see if they are a closed group within the loop.
626 bool MemNode::adr_phi_is_loop_invariant(Node* adr_phi, Node* cast) {
627 // The idea is that the phi-nest must boil down to only CastPP nodes
628 // with the same data. This implies that any path into the loop already
629 // includes such a CastPP, and so the original cast, whatever its input,
630 // must be covered by an equivalent cast, with an earlier control input.
631 ResourceMark rm;
632
633 // The loop entry input of the phi should be the unique dominating
634 // node for every Phi/CastPP in the loop.
635 Unique_Node_List closure;
636 closure.push(adr_phi->in(LoopNode::EntryControl));
637
638 // Add the phi node and the cast to the worklist.
639 Unique_Node_List worklist;
640 worklist.push(adr_phi);
641 if( cast != NULL ){
642 if( !cast->is_ConstraintCast() ) return false;
643 worklist.push(cast);
644 }
645
646 // Begin recursive walk of phi nodes.
647 while( worklist.size() ){
648 // Take a node off the worklist
649 Node *n = worklist.pop();
650 if( !closure.member(n) ){
651 // Add it to the closure.
652 closure.push(n);
653 // Make a sanity check to ensure we don't waste too much time here.
654 if( closure.size() > 20) return false;
655 // This node is OK if:
656 // - it is a cast of an identical value
657 // - or it is a phi node (then we add its inputs to the worklist)
658 // Otherwise, the node is not OK, and we presume the cast is not invariant
659 if( n->is_ConstraintCast() ){
660 worklist.push(n->in(1));
661 } else if( n->is_Phi() ) {
662 for( uint i = 1; i < n->req(); i++ ) {
663 worklist.push(n->in(i));
664 }
665 } else {
666 return false;
667 }
668 }
669 }
670
671 // Quit when the worklist is empty, and we've found no offending nodes.
672 return true;
673 }
674
675 //------------------------------Ideal_DU_postCCP-------------------------------
676 // Find any cast-away of null-ness and keep its control. Null cast-aways are
677 // going away in this pass and we need to make this memory op depend on the
678 // gating null check.
679 Node *MemNode::Ideal_DU_postCCP( PhaseCCP *ccp ) {
680 return Ideal_common_DU_postCCP(ccp, this, in(MemNode::Address));
681 }
682
683 // I tried to leave the CastPP's in. This makes the graph more accurate in
684 // some sense; we get to keep around the knowledge that an oop is not-null
685 // after some test. Alas, the CastPP's interfere with GVN (some values are
686 // the regular oop, some are the CastPP of the oop, all merge at Phi's which
687 // cannot collapse, etc). This cost us 10% on SpecJVM, even when I removed
688 // some of the more trivial cases in the optimizer. Removing more useless
689 // Phi's started allowing Loads to illegally float above null checks. I gave
690 // up on this approach. CNC 10/20/2000
691 // This static method may be called not from MemNode (EncodePNode calls it).
692 // Only the control edge of the node 'n' might be updated.
693 Node *MemNode::Ideal_common_DU_postCCP( PhaseCCP *ccp, Node* n, Node* adr ) {
694 Node *skipped_cast = NULL;
695 // Need a null check? Regular static accesses do not because they are
696 // from constant addresses. Array ops are gated by the range check (which
697 // always includes a NULL check). Just check field ops.
698 if( n->in(MemNode::Control) == NULL ) {
699 // Scan upwards for the highest location we can place this memory op.
700 while( true ) {
701 switch( adr->Opcode() ) {
702
703 case Op_AddP: // No change to NULL-ness, so peek thru AddP's
704 adr = adr->in(AddPNode::Base);
705 continue;
706
707 case Op_DecodeN: // No change to NULL-ness, so peek thru
708 adr = adr->in(1);
709 continue;
710
711 case Op_CastPP:
712 // If the CastPP is useless, just peek on through it.
713 if( ccp->type(adr) == ccp->type(adr->in(1)) ) {
714 // Remember the cast that we've peeked though. If we peek
715 // through more than one, then we end up remembering the highest
716 // one, that is, if in a loop, the one closest to the top.
717 skipped_cast = adr;
718 adr = adr->in(1);
719 continue;
720 }
721 // CastPP is going away in this pass! We need this memory op to be
722 // control-dependent on the test that is guarding the CastPP.
723 ccp->hash_delete(n);
724 n->set_req(MemNode::Control, adr->in(0));
725 ccp->hash_insert(n);
726 return n;
727
728 case Op_Phi:
729 // Attempt to float above a Phi to some dominating point.
730 if (adr->in(0) != NULL && adr->in(0)->is_CountedLoop()) {
731 // If we've already peeked through a Cast (which could have set the
732 // control), we can't float above a Phi, because the skipped Cast
733 // may not be loop invariant.
734 if (adr_phi_is_loop_invariant(adr, skipped_cast)) {
735 adr = adr->in(1);
736 continue;
737 }
738 }
739
740 // Intentional fallthrough!
741
742 // No obvious dominating point. The mem op is pinned below the Phi
743 // by the Phi itself. If the Phi goes away (no true value is merged)
744 // then the mem op can float, but not indefinitely. It must be pinned
745 // behind the controls leading to the Phi.
746 case Op_CheckCastPP:
747 // These usually stick around to change address type, however a
748 // useless one can be elided and we still need to pick up a control edge
749 if (adr->in(0) == NULL) {
750 // This CheckCastPP node has NO control and is likely useless. But we
751 // need check further up the ancestor chain for a control input to keep
752 // the node in place. 4959717.
753 skipped_cast = adr;
754 adr = adr->in(1);
755 continue;
756 }
757 ccp->hash_delete(n);
758 n->set_req(MemNode::Control, adr->in(0));
759 ccp->hash_insert(n);
760 return n;
761
762 // List of "safe" opcodes; those that implicitly block the memory
763 // op below any null check.
764 case Op_CastX2P: // no null checks on native pointers
765 case Op_Parm: // 'this' pointer is not null
766 case Op_LoadP: // Loading from within a klass
767 case Op_LoadN: // Loading from within a klass
768 case Op_LoadKlass: // Loading from within a klass
769 case Op_LoadNKlass: // Loading from within a klass
770 case Op_ConP: // Loading from a klass
771 case Op_ConN: // Loading from a klass
772 case Op_CreateEx: // Sucking up the guts of an exception oop
773 case Op_Con: // Reading from TLS
774 case Op_CMoveP: // CMoveP is pinned
775 case Op_CMoveN: // CMoveN is pinned
776 break; // No progress
777
778 case Op_Proj: // Direct call to an allocation routine
779 case Op_SCMemProj: // Memory state from store conditional ops
780 #ifdef ASSERT
781 {
782 assert(adr->as_Proj()->_con == TypeFunc::Parms, "must be return value");
783 const Node* call = adr->in(0);
784 if (call->is_CallJava()) {
785 const CallJavaNode* call_java = call->as_CallJava();
786 const TypeTuple *r = call_java->tf()->range();
787 assert(r->cnt() > TypeFunc::Parms, "must return value");
788 const Type* ret_type = r->field_at(TypeFunc::Parms);
789 assert(ret_type && ret_type->isa_ptr(), "must return pointer");
790 // We further presume that this is one of
791 // new_instance_Java, new_array_Java, or
792 // the like, but do not assert for this.
793 } else if (call->is_Allocate()) {
794 // similar case to new_instance_Java, etc.
795 } else if (!call->is_CallLeaf()) {
796 // Projections from fetch_oop (OSR) are allowed as well.
797 ShouldNotReachHere();
798 }
799 }
800 #endif
801 break;
802 default:
803 ShouldNotReachHere();
804 }
805 break;
806 }
807 }
808
809 return NULL; // No progress
810 }
811
812
813 //=============================================================================
814 uint LoadNode::size_of() const { return sizeof(*this); }
815 uint LoadNode::cmp( const Node &n ) const
816 { return !Type::cmp( _type, ((LoadNode&)n)._type ); }
817 const Type *LoadNode::bottom_type() const { return _type; }
818 uint LoadNode::ideal_reg() const {
819 return Matcher::base2reg[_type->base()];
820 }
821
822 #ifndef PRODUCT
823 void LoadNode::dump_spec(outputStream *st) const {
824 MemNode::dump_spec(st);
825 if( !Verbose && !WizardMode ) {
826 // standard dump does this in Verbose and WizardMode
827 st->print(" #"); _type->dump_on(st);
828 }
829 }
830 #endif
831
832 #ifdef ASSERT
833 //----------------------------is_immutable_value-------------------------------
834 // Helper function to allow a raw load without control edge for some cases
835 bool LoadNode::is_immutable_value(Node* adr) {
836 return (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() &&
837 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal &&
838 (adr->in(AddPNode::Offset)->find_intptr_t_con(-1) ==
839 in_bytes(JavaThread::osthread_offset())));
840 }
841 #endif
842
843 //----------------------------LoadNode::make-----------------------------------
844 // Polymorphic factory method:
845 Node *LoadNode::make( PhaseGVN& gvn, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt ) {
846 Compile* C = gvn.C;
847
848 // sanity check the alias category against the created node type
849 assert(!(adr_type->isa_oopptr() &&
850 adr_type->offset() == oopDesc::klass_offset_in_bytes()),
851 "use LoadKlassNode instead");
852 assert(!(adr_type->isa_aryptr() &&
853 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
854 "use LoadRangeNode instead");
855 // Check control edge of raw loads
856 assert( ctl != NULL || C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
857 // oop will be recorded in oop map if load crosses safepoint
858 rt->isa_oopptr() || is_immutable_value(adr),
859 "raw memory operations should have control edge");
860 switch (bt) {
861 case T_BOOLEAN: return new (C, 3) LoadUBNode(ctl, mem, adr, adr_type, rt->is_int() );
862 case T_BYTE: return new (C, 3) LoadBNode (ctl, mem, adr, adr_type, rt->is_int() );
863 case T_INT: return new (C, 3) LoadINode (ctl, mem, adr, adr_type, rt->is_int() );
864 case T_CHAR: return new (C, 3) LoadUSNode(ctl, mem, adr, adr_type, rt->is_int() );
865 case T_SHORT: return new (C, 3) LoadSNode (ctl, mem, adr, adr_type, rt->is_int() );
866 case T_LONG: return new (C, 3) LoadLNode (ctl, mem, adr, adr_type, rt->is_long() );
867 case T_FLOAT: return new (C, 3) LoadFNode (ctl, mem, adr, adr_type, rt );
868 case T_DOUBLE: return new (C, 3) LoadDNode (ctl, mem, adr, adr_type, rt );
869 case T_ADDRESS: return new (C, 3) LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr() );
870 case T_OBJECT:
871 #ifdef _LP64
872 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
873 Node* load = gvn.transform(new (C, 3) LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop()));
874 return new (C, 2) DecodeNNode(load, load->bottom_type()->make_ptr());
875 } else
876 #endif
877 {
878 assert(!adr->bottom_type()->is_ptr_to_narrowoop(), "should have got back a narrow oop");
879 return new (C, 3) LoadPNode(ctl, mem, adr, adr_type, rt->is_oopptr());
880 }
881 }
882 ShouldNotReachHere();
883 return (LoadNode*)NULL;
884 }
885
886 LoadLNode* LoadLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt) {
887 bool require_atomic = true;
888 return new (C, 3) LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), require_atomic);
889 }
890
891
892
893
894 //------------------------------hash-------------------------------------------
895 uint LoadNode::hash() const {
896 // unroll addition of interesting fields
897 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
898 }
899
900 //---------------------------can_see_stored_value------------------------------
901 // This routine exists to make sure this set of tests is done the same
902 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
903 // will change the graph shape in a way which makes memory alive twice at the
904 // same time (uses the Oracle model of aliasing), then some
905 // LoadXNode::Identity will fold things back to the equivalence-class model
906 // of aliasing.
907 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const {
908 Node* ld_adr = in(MemNode::Address);
909
910 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
911 Compile::AliasType* atp = tp != NULL ? phase->C->alias_type(tp) : NULL;
912 if (EliminateAutoBox && atp != NULL && atp->index() >= Compile::AliasIdxRaw &&
913 atp->field() != NULL && !atp->field()->is_volatile()) {
914 uint alias_idx = atp->index();
915 bool final = atp->field()->is_final();
916 Node* result = NULL;
917 Node* current = st;
918 // Skip through chains of MemBarNodes checking the MergeMems for
919 // new states for the slice of this load. Stop once any other
920 // kind of node is encountered. Loads from final memory can skip
921 // through any kind of MemBar but normal loads shouldn't skip
922 // through MemBarAcquire since the could allow them to move out of
923 // a synchronized region.
924 while (current->is_Proj()) {
925 int opc = current->in(0)->Opcode();
926 if ((final && opc == Op_MemBarAcquire) ||
927 opc == Op_MemBarRelease || opc == Op_MemBarCPUOrder) {
928 Node* mem = current->in(0)->in(TypeFunc::Memory);
929 if (mem->is_MergeMem()) {
930 MergeMemNode* merge = mem->as_MergeMem();
931 Node* new_st = merge->memory_at(alias_idx);
932 if (new_st == merge->base_memory()) {
933 // Keep searching
934 current = merge->base_memory();
935 continue;
936 }
937 // Save the new memory state for the slice and fall through
938 // to exit.
939 result = new_st;
940 }
941 }
942 break;
943 }
944 if (result != NULL) {
945 st = result;
946 }
947 }
948
949
950 // Loop around twice in the case Load -> Initialize -> Store.
951 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
952 for (int trip = 0; trip <= 1; trip++) {
953
954 if (st->is_Store()) {
955 Node* st_adr = st->in(MemNode::Address);
956 if (!phase->eqv(st_adr, ld_adr)) {
957 // Try harder before giving up... Match raw and non-raw pointers.
958 intptr_t st_off = 0;
959 AllocateNode* alloc = AllocateNode::Ideal_allocation(st_adr, phase, st_off);
960 if (alloc == NULL) return NULL;
961 intptr_t ld_off = 0;
962 AllocateNode* allo2 = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
963 if (alloc != allo2) return NULL;
964 if (ld_off != st_off) return NULL;
965 // At this point we have proven something like this setup:
966 // A = Allocate(...)
967 // L = LoadQ(, AddP(CastPP(, A.Parm),, #Off))
968 // S = StoreQ(, AddP(, A.Parm , #Off), V)
969 // (Actually, we haven't yet proven the Q's are the same.)
970 // In other words, we are loading from a casted version of
971 // the same pointer-and-offset that we stored to.
972 // Thus, we are able to replace L by V.
973 }
974 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
975 if (store_Opcode() != st->Opcode())
976 return NULL;
977 return st->in(MemNode::ValueIn);
978 }
979
980 intptr_t offset = 0; // scratch
981
982 // A load from a freshly-created object always returns zero.
983 // (This can happen after LoadNode::Ideal resets the load's memory input
984 // to find_captured_store, which returned InitializeNode::zero_memory.)
985 if (st->is_Proj() && st->in(0)->is_Allocate() &&
986 st->in(0) == AllocateNode::Ideal_allocation(ld_adr, phase, offset) &&
987 offset >= st->in(0)->as_Allocate()->minimum_header_size()) {
988 // return a zero value for the load's basic type
989 // (This is one of the few places where a generic PhaseTransform
990 // can create new nodes. Think of it as lazily manifesting
991 // virtually pre-existing constants.)
992 return phase->zerocon(memory_type());
993 }
994
995 // A load from an initialization barrier can match a captured store.
996 if (st->is_Proj() && st->in(0)->is_Initialize()) {
997 InitializeNode* init = st->in(0)->as_Initialize();
998 AllocateNode* alloc = init->allocation();
999 if (alloc != NULL &&
1000 alloc == AllocateNode::Ideal_allocation(ld_adr, phase, offset)) {
1001 // examine a captured store value
1002 st = init->find_captured_store(offset, memory_size(), phase);
1003 if (st != NULL)
1004 continue; // take one more trip around
1005 }
1006 }
1007
1008 break;
1009 }
1010
1011 return NULL;
1012 }
1013
1014 //----------------------is_instance_field_load_with_local_phi------------------
1015 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
1016 if( in(MemNode::Memory)->is_Phi() && in(MemNode::Memory)->in(0) == ctrl &&
1017 in(MemNode::Address)->is_AddP() ) {
1018 const TypeOopPtr* t_oop = in(MemNode::Address)->bottom_type()->isa_oopptr();
1019 // Only instances.
1020 if( t_oop != NULL && t_oop->is_known_instance_field() &&
1021 t_oop->offset() != Type::OffsetBot &&
1022 t_oop->offset() != Type::OffsetTop) {
1023 return true;
1024 }
1025 }
1026 return false;
1027 }
1028
1029 //------------------------------Identity---------------------------------------
1030 // Loads are identity if previous store is to same address
1031 Node *LoadNode::Identity( PhaseTransform *phase ) {
1032 // If the previous store-maker is the right kind of Store, and the store is
1033 // to the same address, then we are equal to the value stored.
1034 Node* mem = in(MemNode::Memory);
1035 Node* value = can_see_stored_value(mem, phase);
1036 if( value ) {
1037 // byte, short & char stores truncate naturally.
1038 // A load has to load the truncated value which requires
1039 // some sort of masking operation and that requires an
1040 // Ideal call instead of an Identity call.
1041 if (memory_size() < BytesPerInt) {
1042 // If the input to the store does not fit with the load's result type,
1043 // it must be truncated via an Ideal call.
1044 if (!phase->type(value)->higher_equal(phase->type(this)))
1045 return this;
1046 }
1047 // (This works even when value is a Con, but LoadNode::Value
1048 // usually runs first, producing the singleton type of the Con.)
1049 return value;
1050 }
1051
1052 // Search for an existing data phi which was generated before for the same
1053 // instance's field to avoid infinite generation of phis in a loop.
1054 Node *region = mem->in(0);
1055 if (is_instance_field_load_with_local_phi(region)) {
1056 const TypePtr *addr_t = in(MemNode::Address)->bottom_type()->isa_ptr();
1057 int this_index = phase->C->get_alias_index(addr_t);
1058 int this_offset = addr_t->offset();
1059 int this_id = addr_t->is_oopptr()->instance_id();
1060 const Type* this_type = bottom_type();
1061 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1062 Node* phi = region->fast_out(i);
1063 if (phi->is_Phi() && phi != mem &&
1064 phi->as_Phi()->is_same_inst_field(this_type, this_id, this_index, this_offset)) {
1065 return phi;
1066 }
1067 }
1068 }
1069
1070 return this;
1071 }
1072
1073
1074 // Returns true if the AliasType refers to the field that holds the
1075 // cached box array. Currently only handles the IntegerCache case.
1076 static bool is_autobox_cache(Compile::AliasType* atp) {
1077 if (atp != NULL && atp->field() != NULL) {
1078 ciField* field = atp->field();
1079 ciSymbol* klass = field->holder()->name();
1080 if (field->name() == ciSymbol::cache_field_name() &&
1081 field->holder()->uses_default_loader() &&
1082 klass == ciSymbol::java_lang_Integer_IntegerCache()) {
1083 return true;
1084 }
1085 }
1086 return false;
1087 }
1088
1089 // Fetch the base value in the autobox array
1090 static bool fetch_autobox_base(Compile::AliasType* atp, int& cache_offset) {
1091 if (atp != NULL && atp->field() != NULL) {
1092 ciField* field = atp->field();
1093 ciSymbol* klass = field->holder()->name();
1094 if (field->name() == ciSymbol::cache_field_name() &&
1095 field->holder()->uses_default_loader() &&
1096 klass == ciSymbol::java_lang_Integer_IntegerCache()) {
1097 assert(field->is_constant(), "what?");
1098 ciObjArray* array = field->constant_value().as_object()->as_obj_array();
1099 // Fetch the box object at the base of the array and get its value
1100 ciInstance* box = array->obj_at(0)->as_instance();
1101 ciInstanceKlass* ik = box->klass()->as_instance_klass();
1102 if (ik->nof_nonstatic_fields() == 1) {
1103 // This should be true nonstatic_field_at requires calling
1104 // nof_nonstatic_fields so check it anyway
1105 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1106 cache_offset = c.as_int();
1107 }
1108 return true;
1109 }
1110 }
1111 return false;
1112 }
1113
1114 // Returns true if the AliasType refers to the value field of an
1115 // autobox object. Currently only handles Integer.
1116 static bool is_autobox_object(Compile::AliasType* atp) {
1117 if (atp != NULL && atp->field() != NULL) {
1118 ciField* field = atp->field();
1119 ciSymbol* klass = field->holder()->name();
1120 if (field->name() == ciSymbol::value_name() &&
1121 field->holder()->uses_default_loader() &&
1122 klass == ciSymbol::java_lang_Integer()) {
1123 return true;
1124 }
1125 }
1126 return false;
1127 }
1128
1129
1130 // We're loading from an object which has autobox behaviour.
1131 // If this object is result of a valueOf call we'll have a phi
1132 // merging a newly allocated object and a load from the cache.
1133 // We want to replace this load with the original incoming
1134 // argument to the valueOf call.
1135 Node* LoadNode::eliminate_autobox(PhaseGVN* phase) {
1136 Node* base = in(Address)->in(AddPNode::Base);
1137 if (base->is_Phi() && base->req() == 3) {
1138 AllocateNode* allocation = NULL;
1139 int allocation_index = -1;
1140 int load_index = -1;
1141 for (uint i = 1; i < base->req(); i++) {
1142 allocation = AllocateNode::Ideal_allocation(base->in(i), phase);
1143 if (allocation != NULL) {
1144 allocation_index = i;
1145 load_index = 3 - allocation_index;
1146 break;
1147 }
1148 }
1149 bool has_load = ( allocation != NULL &&
1150 (base->in(load_index)->is_Load() ||
1151 base->in(load_index)->is_DecodeN() &&
1152 base->in(load_index)->in(1)->is_Load()) );
1153 if (has_load && in(Memory)->is_Phi() && in(Memory)->in(0) == base->in(0)) {
1154 // Push the loads from the phi that comes from valueOf up
1155 // through it to allow elimination of the loads and the recovery
1156 // of the original value.
1157 Node* mem_phi = in(Memory);
1158 Node* offset = in(Address)->in(AddPNode::Offset);
1159 Node* region = base->in(0);
1160
1161 Node* in1 = clone();
1162 Node* in1_addr = in1->in(Address)->clone();
1163 in1_addr->set_req(AddPNode::Base, base->in(allocation_index));
1164 in1_addr->set_req(AddPNode::Address, base->in(allocation_index));
1165 in1_addr->set_req(AddPNode::Offset, offset);
1166 in1->set_req(0, region->in(allocation_index));
1167 in1->set_req(Address, in1_addr);
1168 in1->set_req(Memory, mem_phi->in(allocation_index));
1169
1170 Node* in2 = clone();
1171 Node* in2_addr = in2->in(Address)->clone();
1172 in2_addr->set_req(AddPNode::Base, base->in(load_index));
1173 in2_addr->set_req(AddPNode::Address, base->in(load_index));
1174 in2_addr->set_req(AddPNode::Offset, offset);
1175 in2->set_req(0, region->in(load_index));
1176 in2->set_req(Address, in2_addr);
1177 in2->set_req(Memory, mem_phi->in(load_index));
1178
1179 in1_addr = phase->transform(in1_addr);
1180 in1 = phase->transform(in1);
1181 in2_addr = phase->transform(in2_addr);
1182 in2 = phase->transform(in2);
1183
1184 PhiNode* result = PhiNode::make_blank(region, this);
1185 result->set_req(allocation_index, in1);
1186 result->set_req(load_index, in2);
1187 return result;
1188 }
1189 } else if (base->is_Load() ||
1190 base->is_DecodeN() && base->in(1)->is_Load()) {
1191 if (base->is_DecodeN()) {
1192 // Get LoadN node which loads cached Integer object
1193 base = base->in(1);
1194 }
1195 // Eliminate the load of Integer.value for integers from the cache
1196 // array by deriving the value from the index into the array.
1197 // Capture the offset of the load and then reverse the computation.
1198 Node* load_base = base->in(Address)->in(AddPNode::Base);
1199 if (load_base->is_DecodeN()) {
1200 // Get LoadN node which loads IntegerCache.cache field
1201 load_base = load_base->in(1);
1202 }
1203 if (load_base != NULL) {
1204 Compile::AliasType* atp = phase->C->alias_type(load_base->adr_type());
1205 intptr_t cache_offset;
1206 int shift = -1;
1207 Node* cache = NULL;
1208 if (is_autobox_cache(atp)) {
1209 shift = exact_log2(type2aelembytes(T_OBJECT));
1210 cache = AddPNode::Ideal_base_and_offset(load_base->in(Address), phase, cache_offset);
1211 }
1212 if (cache != NULL && base->in(Address)->is_AddP()) {
1213 Node* elements[4];
1214 int count = base->in(Address)->as_AddP()->unpack_offsets(elements, ARRAY_SIZE(elements));
1215 int cache_low;
1216 if (count > 0 && fetch_autobox_base(atp, cache_low)) {
1217 int offset = arrayOopDesc::base_offset_in_bytes(memory_type()) - (cache_low << shift);
1218 // Add up all the offsets making of the address of the load
1219 Node* result = elements[0];
1220 for (int i = 1; i < count; i++) {
1221 result = phase->transform(new (phase->C, 3) AddXNode(result, elements[i]));
1222 }
1223 // Remove the constant offset from the address and then
1224 // remove the scaling of the offset to recover the original index.
1225 result = phase->transform(new (phase->C, 3) AddXNode(result, phase->MakeConX(-offset)));
1226 if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) {
1227 // Peel the shift off directly but wrap it in a dummy node
1228 // since Ideal can't return existing nodes
1229 result = new (phase->C, 3) RShiftXNode(result->in(1), phase->intcon(0));
1230 } else {
1231 result = new (phase->C, 3) RShiftXNode(result, phase->intcon(shift));
1232 }
1233 #ifdef _LP64
1234 result = new (phase->C, 2) ConvL2INode(phase->transform(result));
1235 #endif
1236 return result;
1237 }
1238 }
1239 }
1240 }
1241 return NULL;
1242 }
1243
1244 //------------------------------split_through_phi------------------------------
1245 // Split instance field load through Phi.
1246 Node *LoadNode::split_through_phi(PhaseGVN *phase) {
1247 Node* mem = in(MemNode::Memory);
1248 Node* address = in(MemNode::Address);
1249 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1250 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1251
1252 assert(mem->is_Phi() && (t_oop != NULL) &&
1253 t_oop->is_known_instance_field(), "invalide conditions");
1254
1255 Node *region = mem->in(0);
1256 if (region == NULL) {
1257 return NULL; // Wait stable graph
1258 }
1259 uint cnt = mem->req();
1260 for( uint i = 1; i < cnt; i++ ) {
1261 Node *in = mem->in(i);
1262 if( in == NULL ) {
1263 return NULL; // Wait stable graph
1264 }
1265 }
1266 // Check for loop invariant.
1267 if (cnt == 3) {
1268 for( uint i = 1; i < cnt; i++ ) {
1269 Node *in = mem->in(i);
1270 Node* m = MemNode::optimize_memory_chain(in, addr_t, phase);
1271 if (m == mem) {
1272 set_req(MemNode::Memory, mem->in(cnt - i)); // Skip this phi.
1273 return this;
1274 }
1275 }
1276 }
1277 // Split through Phi (see original code in loopopts.cpp).
1278 assert(phase->C->have_alias_type(addr_t), "instance should have alias type");
1279
1280 // Do nothing here if Identity will find a value
1281 // (to avoid infinite chain of value phis generation).
1282 if ( !phase->eqv(this, this->Identity(phase)) )
1283 return NULL;
1284
1285 // Skip the split if the region dominates some control edge of the address.
1286 if (cnt == 3 && !MemNode::all_controls_dominate(address, region))
1287 return NULL;
1288
1289 const Type* this_type = this->bottom_type();
1290 int this_index = phase->C->get_alias_index(addr_t);
1291 int this_offset = addr_t->offset();
1292 int this_iid = addr_t->is_oopptr()->instance_id();
1293 int wins = 0;
1294 PhaseIterGVN *igvn = phase->is_IterGVN();
1295 Node *phi = new (igvn->C, region->req()) PhiNode(region, this_type, NULL, this_iid, this_index, this_offset);
1296 for( uint i = 1; i < region->req(); i++ ) {
1297 Node *x;
1298 Node* the_clone = NULL;
1299 if( region->in(i) == phase->C->top() ) {
1300 x = phase->C->top(); // Dead path? Use a dead data op
1301 } else {
1302 x = this->clone(); // Else clone up the data op
1303 the_clone = x; // Remember for possible deletion.
1304 // Alter data node to use pre-phi inputs
1305 if( this->in(0) == region ) {
1306 x->set_req( 0, region->in(i) );
1307 } else {
1308 x->set_req( 0, NULL );
1309 }
1310 for( uint j = 1; j < this->req(); j++ ) {
1311 Node *in = this->in(j);
1312 if( in->is_Phi() && in->in(0) == region )
1313 x->set_req( j, in->in(i) ); // Use pre-Phi input for the clone
1314 }
1315 }
1316 // Check for a 'win' on some paths
1317 const Type *t = x->Value(igvn);
1318
1319 bool singleton = t->singleton();
1320
1321 // See comments in PhaseIdealLoop::split_thru_phi().
1322 if( singleton && t == Type::TOP ) {
1323 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1324 }
1325
1326 if( singleton ) {
1327 wins++;
1328 x = igvn->makecon(t);
1329 } else {
1330 // We now call Identity to try to simplify the cloned node.
1331 // Note that some Identity methods call phase->type(this).
1332 // Make sure that the type array is big enough for
1333 // our new node, even though we may throw the node away.
1334 // (This tweaking with igvn only works because x is a new node.)
1335 igvn->set_type(x, t);
1336 // If x is a TypeNode, capture any more-precise type permanently into Node
1337 // otherwise it will be not updated during igvn->transform since
1338 // igvn->type(x) is set to x->Value() already.
1339 x->raise_bottom_type(t);
1340 Node *y = x->Identity(igvn);
1341 if( y != x ) {
1342 wins++;
1343 x = y;
1344 } else {
1345 y = igvn->hash_find(x);
1346 if( y ) {
1347 wins++;
1348 x = y;
1349 } else {
1350 // Else x is a new node we are keeping
1351 // We do not need register_new_node_with_optimizer
1352 // because set_type has already been called.
1353 igvn->_worklist.push(x);
1354 }
1355 }
1356 }
1357 if (x != the_clone && the_clone != NULL)
1358 igvn->remove_dead_node(the_clone);
1359 phi->set_req(i, x);
1360 }
1361 if( wins > 0 ) {
1362 // Record Phi
1363 igvn->register_new_node_with_optimizer(phi);
1364 return phi;
1365 }
1366 igvn->remove_dead_node(phi);
1367 return NULL;
1368 }
1369
1370 //------------------------------Ideal------------------------------------------
1371 // If the load is from Field memory and the pointer is non-null, we can
1372 // zero out the control input.
1373 // If the offset is constant and the base is an object allocation,
1374 // try to hook me up to the exact initializing store.
1375 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1376 Node* p = MemNode::Ideal_common(phase, can_reshape);
1377 if (p) return (p == NodeSentinel) ? NULL : p;
1378
1379 Node* ctrl = in(MemNode::Control);
1380 Node* address = in(MemNode::Address);
1381
1382 // Skip up past a SafePoint control. Cannot do this for Stores because
1383 // pointer stores & cardmarks must stay on the same side of a SafePoint.
1384 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint &&
1385 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw ) {
1386 ctrl = ctrl->in(0);
1387 set_req(MemNode::Control,ctrl);
1388 }
1389
1390 intptr_t ignore = 0;
1391 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1392 if (base != NULL
1393 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
1394 // Check for useless control edge in some common special cases
1395 if (in(MemNode::Control) != NULL
1396 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1397 && all_controls_dominate(base, phase->C->start())) {
1398 // A method-invariant, non-null address (constant or 'this' argument).
1399 set_req(MemNode::Control, NULL);
1400 }
1401
1402 if (EliminateAutoBox && can_reshape) {
1403 assert(!phase->type(base)->higher_equal(TypePtr::NULL_PTR), "the autobox pointer should be non-null");
1404 Compile::AliasType* atp = phase->C->alias_type(adr_type());
1405 if (is_autobox_object(atp)) {
1406 Node* result = eliminate_autobox(phase);
1407 if (result != NULL) return result;
1408 }
1409 }
1410 }
1411
1412 Node* mem = in(MemNode::Memory);
1413 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1414
1415 if (addr_t != NULL) {
1416 // try to optimize our memory input
1417 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, phase);
1418 if (opt_mem != mem) {
1419 set_req(MemNode::Memory, opt_mem);
1420 if (phase->type( opt_mem ) == Type::TOP) return NULL;
1421 return this;
1422 }
1423 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1424 if (can_reshape && opt_mem->is_Phi() &&
1425 (t_oop != NULL) && t_oop->is_known_instance_field()) {
1426 // Split instance field load through Phi.
1427 Node* result = split_through_phi(phase);
1428 if (result != NULL) return result;
1429 }
1430 }
1431
1432 // Check for prior store with a different base or offset; make Load
1433 // independent. Skip through any number of them. Bail out if the stores
1434 // are in an endless dead cycle and report no progress. This is a key
1435 // transform for Reflection. However, if after skipping through the Stores
1436 // we can't then fold up against a prior store do NOT do the transform as
1437 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
1438 // array memory alive twice: once for the hoisted Load and again after the
1439 // bypassed Store. This situation only works if EVERYBODY who does
1440 // anti-dependence work knows how to bypass. I.e. we need all
1441 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
1442 // the alias index stuff. So instead, peek through Stores and IFF we can
1443 // fold up, do so.
1444 Node* prev_mem = find_previous_store(phase);
1445 // Steps (a), (b): Walk past independent stores to find an exact match.
1446 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) {
1447 // (c) See if we can fold up on the spot, but don't fold up here.
1448 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
1449 // just return a prior value, which is done by Identity calls.
1450 if (can_see_stored_value(prev_mem, phase)) {
1451 // Make ready for step (d):
1452 set_req(MemNode::Memory, prev_mem);
1453 return this;
1454 }
1455 }
1456
1457 return NULL; // No further progress
1458 }
1459
1460 // Helper to recognize certain Klass fields which are invariant across
1461 // some group of array types (e.g., int[] or all T[] where T < Object).
1462 const Type*
1463 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1464 ciKlass* klass) const {
1465 if (tkls->offset() == Klass::modifier_flags_offset_in_bytes() + (int)sizeof(oopDesc)) {
1466 // The field is Klass::_modifier_flags. Return its (constant) value.
1467 // (Folds up the 2nd indirection in aClassConstant.getModifiers().)
1468 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags");
1469 return TypeInt::make(klass->modifier_flags());
1470 }
1471 if (tkls->offset() == Klass::access_flags_offset_in_bytes() + (int)sizeof(oopDesc)) {
1472 // The field is Klass::_access_flags. Return its (constant) value.
1473 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1474 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags");
1475 return TypeInt::make(klass->access_flags());
1476 }
1477 if (tkls->offset() == Klass::layout_helper_offset_in_bytes() + (int)sizeof(oopDesc)) {
1478 // The field is Klass::_layout_helper. Return its constant value if known.
1479 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper");
1480 return TypeInt::make(klass->layout_helper());
1481 }
1482
1483 // No match.
1484 return NULL;
1485 }
1486
1487 //------------------------------Value-----------------------------------------
1488 const Type *LoadNode::Value( PhaseTransform *phase ) const {
1489 // Either input is TOP ==> the result is TOP
1490 Node* mem = in(MemNode::Memory);
1491 const Type *t1 = phase->type(mem);
1492 if (t1 == Type::TOP) return Type::TOP;
1493 Node* adr = in(MemNode::Address);
1494 const TypePtr* tp = phase->type(adr)->isa_ptr();
1495 if (tp == NULL || tp->empty()) return Type::TOP;
1496 int off = tp->offset();
1497 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
1498
1499 // Try to guess loaded type from pointer type
1500 if (tp->base() == Type::AryPtr) {
1501 const Type *t = tp->is_aryptr()->elem();
1502 // Don't do this for integer types. There is only potential profit if
1503 // the element type t is lower than _type; that is, for int types, if _type is
1504 // more restrictive than t. This only happens here if one is short and the other
1505 // char (both 16 bits), and in those cases we've made an intentional decision
1506 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
1507 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
1508 //
1509 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
1510 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
1511 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
1512 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
1513 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
1514 // In fact, that could have been the original type of p1, and p1 could have
1515 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
1516 // expression (LShiftL quux 3) independently optimized to the constant 8.
1517 if ((t->isa_int() == NULL) && (t->isa_long() == NULL)
1518 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
1519 // t might actually be lower than _type, if _type is a unique
1520 // concrete subclass of abstract class t.
1521 // Make sure the reference is not into the header, by comparing
1522 // the offset against the offset of the start of the array's data.
1523 // Different array types begin at slightly different offsets (12 vs. 16).
1524 // We choose T_BYTE as an example base type that is least restrictive
1525 // as to alignment, which will therefore produce the smallest
1526 // possible base offset.
1527 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
1528 if ((uint)off >= (uint)min_base_off) { // is the offset beyond the header?
1529 const Type* jt = t->join(_type);
1530 // In any case, do not allow the join, per se, to empty out the type.
1531 if (jt->empty() && !t->empty()) {
1532 // This can happen if a interface-typed array narrows to a class type.
1533 jt = _type;
1534 }
1535
1536 if (EliminateAutoBox && adr->is_AddP()) {
1537 // The pointers in the autobox arrays are always non-null
1538 Node* base = adr->in(AddPNode::Base);
1539 if (base != NULL &&
1540 !phase->type(base)->higher_equal(TypePtr::NULL_PTR)) {
1541 Compile::AliasType* atp = phase->C->alias_type(base->adr_type());
1542 if (is_autobox_cache(atp)) {
1543 return jt->join(TypePtr::NOTNULL)->is_ptr();
1544 }
1545 }
1546 }
1547 return jt;
1548 }
1549 }
1550 } else if (tp->base() == Type::InstPtr) {
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 phase->C->has_unsafe_access(),
1558 "Field accesses must be precise" );
1559 // For oop loads, we expect the _type to be precise
1560 if (OptimizeStringConcat && klass == phase->C->env()->String_klass() &&
1561 adr->is_AddP() && off != Type::OffsetBot) {
1562 // For constant Strings treat the 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 ciObject* string = t->const_oop();
1567 ciConstant constant = string->as_instance()->field_value_by_offset(off);
1568 if (constant.basic_type() == T_INT) {
1569 return TypeInt::make(constant.as_int());
1570 } else if (constant.basic_type() == T_ARRAY) {
1571 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
1572 return TypeNarrowOop::make_from_constant(constant.as_object());
1573 } else {
1574 return TypeOopPtr::make_from_constant(constant.as_object());
1575 }
1576 }
1577 }
1578 }
1579 } else if (tp->base() == Type::KlassPtr) {
1580 assert( off != Type::OffsetBot ||
1581 // arrays can be cast to Objects
1582 tp->is_klassptr()->klass()->is_java_lang_Object() ||
1583 // also allow array-loading from the primary supertype
1584 // array during subtype checks
1585 Opcode() == Op_LoadKlass,
1586 "Field accesses must be precise" );
1587 // For klass/static loads, we expect the _type to be precise
1588 }
1589
1590 const TypeKlassPtr *tkls = tp->isa_klassptr();
1591 if (tkls != NULL && !StressReflectiveCode) {
1592 ciKlass* klass = tkls->klass();
1593 if (klass->is_loaded() && tkls->klass_is_exact()) {
1594 // We are loading a field from a Klass metaobject whose identity
1595 // is known at compile time (the type is "exact" or "precise").
1596 // Check for fields we know are maintained as constants by the VM.
1597 if (tkls->offset() == Klass::super_check_offset_offset_in_bytes() + (int)sizeof(oopDesc)) {
1598 // The field is Klass::_super_check_offset. Return its (constant) value.
1599 // (Folds up type checking code.)
1600 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
1601 return TypeInt::make(klass->super_check_offset());
1602 }
1603 // Compute index into primary_supers array
1604 juint depth = (tkls->offset() - (Klass::primary_supers_offset_in_bytes() + (int)sizeof(oopDesc))) / sizeof(klassOop);
1605 // Check for overflowing; use unsigned compare to handle the negative case.
1606 if( depth < ciKlass::primary_super_limit() ) {
1607 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1608 // (Folds up type checking code.)
1609 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1610 ciKlass *ss = klass->super_of_depth(depth);
1611 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1612 }
1613 const Type* aift = load_array_final_field(tkls, klass);
1614 if (aift != NULL) return aift;
1615 if (tkls->offset() == in_bytes(arrayKlass::component_mirror_offset()) + (int)sizeof(oopDesc)
1616 && klass->is_array_klass()) {
1617 // The field is arrayKlass::_component_mirror. Return its (constant) value.
1618 // (Folds up aClassConstant.getComponentType, common in Arrays.copyOf.)
1619 assert(Opcode() == Op_LoadP, "must load an oop from _component_mirror");
1620 return TypeInstPtr::make(klass->as_array_klass()->component_mirror());
1621 }
1622 if (tkls->offset() == Klass::java_mirror_offset_in_bytes() + (int)sizeof(oopDesc)) {
1623 // The field is Klass::_java_mirror. Return its (constant) value.
1624 // (Folds up the 2nd indirection in anObjConstant.getClass().)
1625 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
1626 return TypeInstPtr::make(klass->java_mirror());
1627 }
1628 }
1629
1630 // We can still check if we are loading from the primary_supers array at a
1631 // shallow enough depth. Even though the klass is not exact, entries less
1632 // than or equal to its super depth are correct.
1633 if (klass->is_loaded() ) {
1634 ciType *inner = klass->klass();
1635 while( inner->is_obj_array_klass() )
1636 inner = inner->as_obj_array_klass()->base_element_type();
1637 if( inner->is_instance_klass() &&
1638 !inner->as_instance_klass()->flags().is_interface() ) {
1639 // Compute index into primary_supers array
1640 juint depth = (tkls->offset() - (Klass::primary_supers_offset_in_bytes() + (int)sizeof(oopDesc))) / sizeof(klassOop);
1641 // Check for overflowing; use unsigned compare to handle the negative case.
1642 if( depth < ciKlass::primary_super_limit() &&
1643 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case
1644 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1645 // (Folds up type checking code.)
1646 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1647 ciKlass *ss = klass->super_of_depth(depth);
1648 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1649 }
1650 }
1651 }
1652
1653 // If the type is enough to determine that the thing is not an array,
1654 // we can give the layout_helper a positive interval type.
1655 // This will help short-circuit some reflective code.
1656 if (tkls->offset() == Klass::layout_helper_offset_in_bytes() + (int)sizeof(oopDesc)
1657 && !klass->is_array_klass() // not directly typed as an array
1658 && !klass->is_interface() // specifically not Serializable & Cloneable
1659 && !klass->is_java_lang_Object() // not the supertype of all T[]
1660 ) {
1661 // Note: When interfaces are reliable, we can narrow the interface
1662 // test to (klass != Serializable && klass != Cloneable).
1663 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
1664 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
1665 // The key property of this type is that it folds up tests
1666 // for array-ness, since it proves that the layout_helper is positive.
1667 // Thus, a generic value like the basic object layout helper works fine.
1668 return TypeInt::make(min_size, max_jint, Type::WidenMin);
1669 }
1670 }
1671
1672 // If we are loading from a freshly-allocated object, produce a zero,
1673 // if the load is provably beyond the header of the object.
1674 // (Also allow a variable load from a fresh array to produce zero.)
1675 if (ReduceFieldZeroing) {
1676 Node* value = can_see_stored_value(mem,phase);
1677 if (value != NULL && value->is_Con())
1678 return value->bottom_type();
1679 }
1680
1681 const TypeOopPtr *tinst = tp->isa_oopptr();
1682 if (tinst != NULL && tinst->is_known_instance_field()) {
1683 // If we have an instance type and our memory input is the
1684 // programs's initial memory state, there is no matching store,
1685 // so just return a zero of the appropriate type
1686 Node *mem = in(MemNode::Memory);
1687 if (mem->is_Parm() && mem->in(0)->is_Start()) {
1688 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
1689 return Type::get_zero_type(_type->basic_type());
1690 }
1691 }
1692 return _type;
1693 }
1694
1695 //------------------------------match_edge-------------------------------------
1696 // Do we Match on this edge index or not? Match only the address.
1697 uint LoadNode::match_edge(uint idx) const {
1698 return idx == MemNode::Address;
1699 }
1700
1701 //--------------------------LoadBNode::Ideal--------------------------------------
1702 //
1703 // If the previous store is to the same address as this load,
1704 // and the value stored was larger than a byte, replace this load
1705 // with the value stored truncated to a byte. If no truncation is
1706 // needed, the replacement is done in LoadNode::Identity().
1707 //
1708 Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1709 Node* mem = in(MemNode::Memory);
1710 Node* value = can_see_stored_value(mem,phase);
1711 if( value && !phase->type(value)->higher_equal( _type ) ) {
1712 Node *result = phase->transform( new (phase->C, 3) LShiftINode(value, phase->intcon(24)) );
1713 return new (phase->C, 3) RShiftINode(result, phase->intcon(24));
1714 }
1715 // Identity call will handle the case where truncation is not needed.
1716 return LoadNode::Ideal(phase, can_reshape);
1717 }
1718
1719 //--------------------------LoadUBNode::Ideal-------------------------------------
1720 //
1721 // If the previous store is to the same address as this load,
1722 // and the value stored was larger than a byte, replace this load
1723 // with the value stored truncated to a byte. If no truncation is
1724 // needed, the replacement is done in LoadNode::Identity().
1725 //
1726 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
1727 Node* mem = in(MemNode::Memory);
1728 Node* value = can_see_stored_value(mem, phase);
1729 if (value && !phase->type(value)->higher_equal(_type))
1730 return new (phase->C, 3) AndINode(value, phase->intcon(0xFF));
1731 // Identity call will handle the case where truncation is not needed.
1732 return LoadNode::Ideal(phase, can_reshape);
1733 }
1734
1735 //--------------------------LoadUSNode::Ideal-------------------------------------
1736 //
1737 // If the previous store is to the same address as this load,
1738 // and the value stored was larger than a char, replace this load
1739 // with the value stored truncated to a char. If no truncation is
1740 // needed, the replacement is done in LoadNode::Identity().
1741 //
1742 Node *LoadUSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1743 Node* mem = in(MemNode::Memory);
1744 Node* value = can_see_stored_value(mem,phase);
1745 if( value && !phase->type(value)->higher_equal( _type ) )
1746 return new (phase->C, 3) AndINode(value,phase->intcon(0xFFFF));
1747 // Identity call will handle the case where truncation is not needed.
1748 return LoadNode::Ideal(phase, can_reshape);
1749 }
1750
1751 //--------------------------LoadSNode::Ideal--------------------------------------
1752 //
1753 // If the previous store is to the same address as this load,
1754 // and the value stored was larger than a short, replace this load
1755 // with the value stored truncated to a short. If no truncation is
1756 // needed, the replacement is done in LoadNode::Identity().
1757 //
1758 Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1759 Node* mem = in(MemNode::Memory);
1760 Node* value = can_see_stored_value(mem,phase);
1761 if( value && !phase->type(value)->higher_equal( _type ) ) {
1762 Node *result = phase->transform( new (phase->C, 3) LShiftINode(value, phase->intcon(16)) );
1763 return new (phase->C, 3) RShiftINode(result, phase->intcon(16));
1764 }
1765 // Identity call will handle the case where truncation is not needed.
1766 return LoadNode::Ideal(phase, can_reshape);
1767 }
1768
1769 //=============================================================================
1770 //----------------------------LoadKlassNode::make------------------------------
1771 // Polymorphic factory method:
1772 Node *LoadKlassNode::make( PhaseGVN& gvn, Node *mem, Node *adr, const TypePtr* at, const TypeKlassPtr *tk ) {
1773 Compile* C = gvn.C;
1774 Node *ctl = NULL;
1775 // sanity check the alias category against the created node type
1776 const TypeOopPtr *adr_type = adr->bottom_type()->isa_oopptr();
1777 assert(adr_type != NULL, "expecting TypeOopPtr");
1778 #ifdef _LP64
1779 if (adr_type->is_ptr_to_narrowoop()) {
1780 Node* load_klass = gvn.transform(new (C, 3) LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowoop()));
1781 return new (C, 2) DecodeNNode(load_klass, load_klass->bottom_type()->make_ptr());
1782 }
1783 #endif
1784 assert(!adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
1785 return new (C, 3) LoadKlassNode(ctl, mem, adr, at, tk);
1786 }
1787
1788 //------------------------------Value------------------------------------------
1789 const Type *LoadKlassNode::Value( PhaseTransform *phase ) const {
1790 return klass_value_common(phase);
1791 }
1792
1793 const Type *LoadNode::klass_value_common( PhaseTransform *phase ) const {
1794 // Either input is TOP ==> the result is TOP
1795 const Type *t1 = phase->type( in(MemNode::Memory) );
1796 if (t1 == Type::TOP) return Type::TOP;
1797 Node *adr = in(MemNode::Address);
1798 const Type *t2 = phase->type( adr );
1799 if (t2 == Type::TOP) return Type::TOP;
1800 const TypePtr *tp = t2->is_ptr();
1801 if (TypePtr::above_centerline(tp->ptr()) ||
1802 tp->ptr() == TypePtr::Null) return Type::TOP;
1803
1804 // Return a more precise klass, if possible
1805 const TypeInstPtr *tinst = tp->isa_instptr();
1806 if (tinst != NULL) {
1807 ciInstanceKlass* ik = tinst->klass()->as_instance_klass();
1808 int offset = tinst->offset();
1809 if (ik == phase->C->env()->Class_klass()
1810 && (offset == java_lang_Class::klass_offset_in_bytes() ||
1811 offset == java_lang_Class::array_klass_offset_in_bytes())) {
1812 // We are loading a special hidden field from a Class mirror object,
1813 // the field which points to the VM's Klass metaobject.
1814 ciType* t = tinst->java_mirror_type();
1815 // java_mirror_type returns non-null for compile-time Class constants.
1816 if (t != NULL) {
1817 // constant oop => constant klass
1818 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
1819 return TypeKlassPtr::make(ciArrayKlass::make(t));
1820 }
1821 if (!t->is_klass()) {
1822 // a primitive Class (e.g., int.class) has NULL for a klass field
1823 return TypePtr::NULL_PTR;
1824 }
1825 // (Folds up the 1st indirection in aClassConstant.getModifiers().)
1826 return TypeKlassPtr::make(t->as_klass());
1827 }
1828 // non-constant mirror, so we can't tell what's going on
1829 }
1830 if( !ik->is_loaded() )
1831 return _type; // Bail out if not loaded
1832 if (offset == oopDesc::klass_offset_in_bytes()) {
1833 if (tinst->klass_is_exact()) {
1834 return TypeKlassPtr::make(ik);
1835 }
1836 // See if we can become precise: no subklasses and no interface
1837 // (Note: We need to support verified interfaces.)
1838 if (!ik->is_interface() && !ik->has_subklass()) {
1839 //assert(!UseExactTypes, "this code should be useless with exact types");
1840 // Add a dependence; if any subclass added we need to recompile
1841 if (!ik->is_final()) {
1842 // %%% should use stronger assert_unique_concrete_subtype instead
1843 phase->C->dependencies()->assert_leaf_type(ik);
1844 }
1845 // Return precise klass
1846 return TypeKlassPtr::make(ik);
1847 }
1848
1849 // Return root of possible klass
1850 return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/);
1851 }
1852 }
1853
1854 // Check for loading klass from an array
1855 const TypeAryPtr *tary = tp->isa_aryptr();
1856 if( tary != NULL ) {
1857 ciKlass *tary_klass = tary->klass();
1858 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP
1859 && tary->offset() == oopDesc::klass_offset_in_bytes()) {
1860 if (tary->klass_is_exact()) {
1861 return TypeKlassPtr::make(tary_klass);
1862 }
1863 ciArrayKlass *ak = tary->klass()->as_array_klass();
1864 // If the klass is an object array, we defer the question to the
1865 // array component klass.
1866 if( ak->is_obj_array_klass() ) {
1867 assert( ak->is_loaded(), "" );
1868 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass();
1869 if( base_k->is_loaded() && base_k->is_instance_klass() ) {
1870 ciInstanceKlass* ik = base_k->as_instance_klass();
1871 // See if we can become precise: no subklasses and no interface
1872 if (!ik->is_interface() && !ik->has_subklass()) {
1873 //assert(!UseExactTypes, "this code should be useless with exact types");
1874 // Add a dependence; if any subclass added we need to recompile
1875 if (!ik->is_final()) {
1876 phase->C->dependencies()->assert_leaf_type(ik);
1877 }
1878 // Return precise array klass
1879 return TypeKlassPtr::make(ak);
1880 }
1881 }
1882 return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/);
1883 } else { // Found a type-array?
1884 //assert(!UseExactTypes, "this code should be useless with exact types");
1885 assert( ak->is_type_array_klass(), "" );
1886 return TypeKlassPtr::make(ak); // These are always precise
1887 }
1888 }
1889 }
1890
1891 // Check for loading klass from an array klass
1892 const TypeKlassPtr *tkls = tp->isa_klassptr();
1893 if (tkls != NULL && !StressReflectiveCode) {
1894 ciKlass* klass = tkls->klass();
1895 if( !klass->is_loaded() )
1896 return _type; // Bail out if not loaded
1897 if( klass->is_obj_array_klass() &&
1898 (uint)tkls->offset() == objArrayKlass::element_klass_offset_in_bytes() + sizeof(oopDesc)) {
1899 ciKlass* elem = klass->as_obj_array_klass()->element_klass();
1900 // // Always returning precise element type is incorrect,
1901 // // e.g., element type could be object and array may contain strings
1902 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
1903
1904 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
1905 // according to the element type's subclassing.
1906 return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/);
1907 }
1908 if( klass->is_instance_klass() && tkls->klass_is_exact() &&
1909 (uint)tkls->offset() == Klass::super_offset_in_bytes() + sizeof(oopDesc)) {
1910 ciKlass* sup = klass->as_instance_klass()->super();
1911 // The field is Klass::_super. Return its (constant) value.
1912 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
1913 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR;
1914 }
1915 }
1916
1917 // Bailout case
1918 return LoadNode::Value(phase);
1919 }
1920
1921 //------------------------------Identity---------------------------------------
1922 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
1923 // Also feed through the klass in Allocate(...klass...)._klass.
1924 Node* LoadKlassNode::Identity( PhaseTransform *phase ) {
1925 return klass_identity_common(phase);
1926 }
1927
1928 Node* LoadNode::klass_identity_common(PhaseTransform *phase ) {
1929 Node* x = LoadNode::Identity(phase);
1930 if (x != this) return x;
1931
1932 // Take apart the address into an oop and and offset.
1933 // Return 'this' if we cannot.
1934 Node* adr = in(MemNode::Address);
1935 intptr_t offset = 0;
1936 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
1937 if (base == NULL) return this;
1938 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
1939 if (toop == NULL) return this;
1940
1941 // We can fetch the klass directly through an AllocateNode.
1942 // This works even if the klass is not constant (clone or newArray).
1943 if (offset == oopDesc::klass_offset_in_bytes()) {
1944 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
1945 if (allocated_klass != NULL) {
1946 return allocated_klass;
1947 }
1948 }
1949
1950 // Simplify k.java_mirror.as_klass to plain k, where k is a klassOop.
1951 // Simplify ak.component_mirror.array_klass to plain ak, ak an arrayKlass.
1952 // See inline_native_Class_query for occurrences of these patterns.
1953 // Java Example: x.getClass().isAssignableFrom(y)
1954 // Java Example: Array.newInstance(x.getClass().getComponentType(), n)
1955 //
1956 // This improves reflective code, often making the Class
1957 // mirror go completely dead. (Current exception: Class
1958 // mirrors may appear in debug info, but we could clean them out by
1959 // introducing a new debug info operator for klassOop.java_mirror).
1960 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass()
1961 && (offset == java_lang_Class::klass_offset_in_bytes() ||
1962 offset == java_lang_Class::array_klass_offset_in_bytes())) {
1963 // We are loading a special hidden field from a Class mirror,
1964 // the field which points to its Klass or arrayKlass metaobject.
1965 if (base->is_Load()) {
1966 Node* adr2 = base->in(MemNode::Address);
1967 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
1968 if (tkls != NULL && !tkls->empty()
1969 && (tkls->klass()->is_instance_klass() ||
1970 tkls->klass()->is_array_klass())
1971 && adr2->is_AddP()
1972 ) {
1973 int mirror_field = Klass::java_mirror_offset_in_bytes();
1974 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
1975 mirror_field = in_bytes(arrayKlass::component_mirror_offset());
1976 }
1977 if (tkls->offset() == mirror_field + (int)sizeof(oopDesc)) {
1978 return adr2->in(AddPNode::Base);
1979 }
1980 }
1981 }
1982 }
1983
1984 return this;
1985 }
1986
1987
1988 //------------------------------Value------------------------------------------
1989 const Type *LoadNKlassNode::Value( PhaseTransform *phase ) const {
1990 const Type *t = klass_value_common(phase);
1991 if (t == Type::TOP)
1992 return t;
1993
1994 return t->make_narrowoop();
1995 }
1996
1997 //------------------------------Identity---------------------------------------
1998 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
1999 // Also feed through the klass in Allocate(...klass...)._klass.
2000 Node* LoadNKlassNode::Identity( PhaseTransform *phase ) {
2001 Node *x = klass_identity_common(phase);
2002
2003 const Type *t = phase->type( x );
2004 if( t == Type::TOP ) return x;
2005 if( t->isa_narrowoop()) return x;
2006
2007 return phase->transform(new (phase->C, 2) EncodePNode(x, t->make_narrowoop()));
2008 }
2009
2010 //------------------------------Value-----------------------------------------
2011 const Type *LoadRangeNode::Value( PhaseTransform *phase ) const {
2012 // Either input is TOP ==> the result is TOP
2013 const Type *t1 = phase->type( in(MemNode::Memory) );
2014 if( t1 == Type::TOP ) return Type::TOP;
2015 Node *adr = in(MemNode::Address);
2016 const Type *t2 = phase->type( adr );
2017 if( t2 == Type::TOP ) return Type::TOP;
2018 const TypePtr *tp = t2->is_ptr();
2019 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
2020 const TypeAryPtr *tap = tp->isa_aryptr();
2021 if( !tap ) return _type;
2022 return tap->size();
2023 }
2024
2025 //-------------------------------Ideal---------------------------------------
2026 // Feed through the length in AllocateArray(...length...)._length.
2027 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2028 Node* p = MemNode::Ideal_common(phase, can_reshape);
2029 if (p) return (p == NodeSentinel) ? NULL : p;
2030
2031 // Take apart the address into an oop and and offset.
2032 // Return 'this' if we cannot.
2033 Node* adr = in(MemNode::Address);
2034 intptr_t offset = 0;
2035 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2036 if (base == NULL) return NULL;
2037 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2038 if (tary == NULL) return NULL;
2039
2040 // We can fetch the length directly through an AllocateArrayNode.
2041 // This works even if the length is not constant (clone or newArray).
2042 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2043 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2044 if (alloc != NULL) {
2045 Node* allocated_length = alloc->Ideal_length();
2046 Node* len = alloc->make_ideal_length(tary, phase);
2047 if (allocated_length != len) {
2048 // New CastII improves on this.
2049 return len;
2050 }
2051 }
2052 }
2053
2054 return NULL;
2055 }
2056
2057 //------------------------------Identity---------------------------------------
2058 // Feed through the length in AllocateArray(...length...)._length.
2059 Node* LoadRangeNode::Identity( PhaseTransform *phase ) {
2060 Node* x = LoadINode::Identity(phase);
2061 if (x != this) return x;
2062
2063 // Take apart the address into an oop and and offset.
2064 // Return 'this' if we cannot.
2065 Node* adr = in(MemNode::Address);
2066 intptr_t offset = 0;
2067 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2068 if (base == NULL) return this;
2069 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2070 if (tary == NULL) return this;
2071
2072 // We can fetch the length directly through an AllocateArrayNode.
2073 // This works even if the length is not constant (clone or newArray).
2074 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2075 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2076 if (alloc != NULL) {
2077 Node* allocated_length = alloc->Ideal_length();
2078 // Do not allow make_ideal_length to allocate a CastII node.
2079 Node* len = alloc->make_ideal_length(tary, phase, false);
2080 if (allocated_length == len) {
2081 // Return allocated_length only if it would not be improved by a CastII.
2082 return allocated_length;
2083 }
2084 }
2085 }
2086
2087 return this;
2088
2089 }
2090
2091 //=============================================================================
2092 //---------------------------StoreNode::make-----------------------------------
2093 // Polymorphic factory method:
2094 StoreNode* StoreNode::make( PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt ) {
2095 Compile* C = gvn.C;
2096 assert( C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2097 ctl != NULL, "raw memory operations should have control edge");
2098
2099 switch (bt) {
2100 case T_BOOLEAN:
2101 case T_BYTE: return new (C, 4) StoreBNode(ctl, mem, adr, adr_type, val);
2102 case T_INT: return new (C, 4) StoreINode(ctl, mem, adr, adr_type, val);
2103 case T_CHAR:
2104 case T_SHORT: return new (C, 4) StoreCNode(ctl, mem, adr, adr_type, val);
2105 case T_LONG: return new (C, 4) StoreLNode(ctl, mem, adr, adr_type, val);
2106 case T_FLOAT: return new (C, 4) StoreFNode(ctl, mem, adr, adr_type, val);
2107 case T_DOUBLE: return new (C, 4) StoreDNode(ctl, mem, adr, adr_type, val);
2108 case T_ADDRESS:
2109 case T_OBJECT:
2110 #ifdef _LP64
2111 if (adr->bottom_type()->is_ptr_to_narrowoop() ||
2112 (UseCompressedOops && val->bottom_type()->isa_klassptr() &&
2113 adr->bottom_type()->isa_rawptr())) {
2114 val = gvn.transform(new (C, 2) EncodePNode(val, val->bottom_type()->make_narrowoop()));
2115 return new (C, 4) StoreNNode(ctl, mem, adr, adr_type, val);
2116 } else
2117 #endif
2118 {
2119 return new (C, 4) StorePNode(ctl, mem, adr, adr_type, val);
2120 }
2121 }
2122 ShouldNotReachHere();
2123 return (StoreNode*)NULL;
2124 }
2125
2126 StoreLNode* StoreLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val) {
2127 bool require_atomic = true;
2128 return new (C, 4) StoreLNode(ctl, mem, adr, adr_type, val, require_atomic);
2129 }
2130
2131
2132 //--------------------------bottom_type----------------------------------------
2133 const Type *StoreNode::bottom_type() const {
2134 return Type::MEMORY;
2135 }
2136
2137 //------------------------------hash-------------------------------------------
2138 uint StoreNode::hash() const {
2139 // unroll addition of interesting fields
2140 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2141
2142 // Since they are not commoned, do not hash them:
2143 return NO_HASH;
2144 }
2145
2146 //------------------------------Ideal------------------------------------------
2147 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
2148 // When a store immediately follows a relevant allocation/initialization,
2149 // try to capture it into the initialization, or hoist it above.
2150 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2151 Node* p = MemNode::Ideal_common(phase, can_reshape);
2152 if (p) return (p == NodeSentinel) ? NULL : p;
2153
2154 Node* mem = in(MemNode::Memory);
2155 Node* address = in(MemNode::Address);
2156
2157 // Back-to-back stores to same address? Fold em up.
2158 // Generally unsafe if I have intervening uses...
2159 if (mem->is_Store() && phase->eqv_uncast(mem->in(MemNode::Address), address)) {
2160 // Looking at a dead closed cycle of memory?
2161 assert(mem != mem->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
2162
2163 assert(Opcode() == mem->Opcode() ||
2164 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw,
2165 "no mismatched stores, except on raw memory");
2166
2167 if (mem->outcnt() == 1 && // check for intervening uses
2168 mem->as_Store()->memory_size() <= this->memory_size()) {
2169 // If anybody other than 'this' uses 'mem', we cannot fold 'mem' away.
2170 // For example, 'mem' might be the final state at a conditional return.
2171 // Or, 'mem' might be used by some node which is live at the same time
2172 // 'this' is live, which might be unschedulable. So, require exactly
2173 // ONE user, the 'this' store, until such time as we clone 'mem' for
2174 // each of 'mem's uses (thus making the exactly-1-user-rule hold true).
2175 if (can_reshape) { // (%%% is this an anachronism?)
2176 set_req_X(MemNode::Memory, mem->in(MemNode::Memory),
2177 phase->is_IterGVN());
2178 } else {
2179 // It's OK to do this in the parser, since DU info is always accurate,
2180 // and the parser always refers to nodes via SafePointNode maps.
2181 set_req(MemNode::Memory, mem->in(MemNode::Memory));
2182 }
2183 return this;
2184 }
2185 }
2186
2187 // Capture an unaliased, unconditional, simple store into an initializer.
2188 // Or, if it is independent of the allocation, hoist it above the allocation.
2189 if (ReduceFieldZeroing && /*can_reshape &&*/
2190 mem->is_Proj() && mem->in(0)->is_Initialize()) {
2191 InitializeNode* init = mem->in(0)->as_Initialize();
2192 intptr_t offset = init->can_capture_store(this, phase);
2193 if (offset > 0) {
2194 Node* moved = init->capture_store(this, offset, phase);
2195 // If the InitializeNode captured me, it made a raw copy of me,
2196 // and I need to disappear.
2197 if (moved != NULL) {
2198 // %%% hack to ensure that Ideal returns a new node:
2199 mem = MergeMemNode::make(phase->C, mem);
2200 return mem; // fold me away
2201 }
2202 }
2203 }
2204
2205 return NULL; // No further progress
2206 }
2207
2208 //------------------------------Value-----------------------------------------
2209 const Type *StoreNode::Value( PhaseTransform *phase ) const {
2210 // Either input is TOP ==> the result is TOP
2211 const Type *t1 = phase->type( in(MemNode::Memory) );
2212 if( t1 == Type::TOP ) return Type::TOP;
2213 const Type *t2 = phase->type( in(MemNode::Address) );
2214 if( t2 == Type::TOP ) return Type::TOP;
2215 const Type *t3 = phase->type( in(MemNode::ValueIn) );
2216 if( t3 == Type::TOP ) return Type::TOP;
2217 return Type::MEMORY;
2218 }
2219
2220 //------------------------------Identity---------------------------------------
2221 // Remove redundant stores:
2222 // Store(m, p, Load(m, p)) changes to m.
2223 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
2224 Node *StoreNode::Identity( PhaseTransform *phase ) {
2225 Node* mem = in(MemNode::Memory);
2226 Node* adr = in(MemNode::Address);
2227 Node* val = in(MemNode::ValueIn);
2228
2229 // Load then Store? Then the Store is useless
2230 if (val->is_Load() &&
2231 phase->eqv_uncast( val->in(MemNode::Address), adr ) &&
2232 phase->eqv_uncast( val->in(MemNode::Memory ), mem ) &&
2233 val->as_Load()->store_Opcode() == Opcode()) {
2234 return mem;
2235 }
2236
2237 // Two stores in a row of the same value?
2238 if (mem->is_Store() &&
2239 phase->eqv_uncast( mem->in(MemNode::Address), adr ) &&
2240 phase->eqv_uncast( mem->in(MemNode::ValueIn), val ) &&
2241 mem->Opcode() == Opcode()) {
2242 return mem;
2243 }
2244
2245 // Store of zero anywhere into a freshly-allocated object?
2246 // Then the store is useless.
2247 // (It must already have been captured by the InitializeNode.)
2248 if (ReduceFieldZeroing && phase->type(val)->is_zero_type()) {
2249 // a newly allocated object is already all-zeroes everywhere
2250 if (mem->is_Proj() && mem->in(0)->is_Allocate()) {
2251 return mem;
2252 }
2253
2254 // the store may also apply to zero-bits in an earlier object
2255 Node* prev_mem = find_previous_store(phase);
2256 // Steps (a), (b): Walk past independent stores to find an exact match.
2257 if (prev_mem != NULL) {
2258 Node* prev_val = can_see_stored_value(prev_mem, phase);
2259 if (prev_val != NULL && phase->eqv(prev_val, val)) {
2260 // prev_val and val might differ by a cast; it would be good
2261 // to keep the more informative of the two.
2262 return mem;
2263 }
2264 }
2265 }
2266
2267 return this;
2268 }
2269
2270 //------------------------------match_edge-------------------------------------
2271 // Do we Match on this edge index or not? Match only memory & value
2272 uint StoreNode::match_edge(uint idx) const {
2273 return idx == MemNode::Address || idx == MemNode::ValueIn;
2274 }
2275
2276 //------------------------------cmp--------------------------------------------
2277 // Do not common stores up together. They generally have to be split
2278 // back up anyways, so do not bother.
2279 uint StoreNode::cmp( const Node &n ) const {
2280 return (&n == this); // Always fail except on self
2281 }
2282
2283 //------------------------------Ideal_masked_input-----------------------------
2284 // Check for a useless mask before a partial-word store
2285 // (StoreB ... (AndI valIn conIa) )
2286 // If (conIa & mask == mask) this simplifies to
2287 // (StoreB ... (valIn) )
2288 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
2289 Node *val = in(MemNode::ValueIn);
2290 if( val->Opcode() == Op_AndI ) {
2291 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2292 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
2293 set_req(MemNode::ValueIn, val->in(1));
2294 return this;
2295 }
2296 }
2297 return NULL;
2298 }
2299
2300
2301 //------------------------------Ideal_sign_extended_input----------------------
2302 // Check for useless sign-extension before a partial-word store
2303 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) )
2304 // If (conIL == conIR && conIR <= num_bits) this simplifies to
2305 // (StoreB ... (valIn) )
2306 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) {
2307 Node *val = in(MemNode::ValueIn);
2308 if( val->Opcode() == Op_RShiftI ) {
2309 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2310 if( t && t->is_con() && (t->get_con() <= num_bits) ) {
2311 Node *shl = val->in(1);
2312 if( shl->Opcode() == Op_LShiftI ) {
2313 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int();
2314 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) {
2315 set_req(MemNode::ValueIn, shl->in(1));
2316 return this;
2317 }
2318 }
2319 }
2320 }
2321 return NULL;
2322 }
2323
2324 //------------------------------value_never_loaded-----------------------------------
2325 // Determine whether there are any possible loads of the value stored.
2326 // For simplicity, we actually check if there are any loads from the
2327 // address stored to, not just for loads of the value stored by this node.
2328 //
2329 bool StoreNode::value_never_loaded( PhaseTransform *phase) const {
2330 Node *adr = in(Address);
2331 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
2332 if (adr_oop == NULL)
2333 return false;
2334 if (!adr_oop->is_known_instance_field())
2335 return false; // if not a distinct instance, there may be aliases of the address
2336 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
2337 Node *use = adr->fast_out(i);
2338 int opc = use->Opcode();
2339 if (use->is_Load() || use->is_LoadStore()) {
2340 return false;
2341 }
2342 }
2343 return true;
2344 }
2345
2346 //=============================================================================
2347 //------------------------------Ideal------------------------------------------
2348 // If the store is from an AND mask that leaves the low bits untouched, then
2349 // we can skip the AND operation. If the store is from a sign-extension
2350 // (a left shift, then right shift) we can skip both.
2351 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
2352 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
2353 if( progress != NULL ) return progress;
2354
2355 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
2356 if( progress != NULL ) return progress;
2357
2358 // Finally check the default case
2359 return StoreNode::Ideal(phase, can_reshape);
2360 }
2361
2362 //=============================================================================
2363 //------------------------------Ideal------------------------------------------
2364 // If the store is from an AND mask that leaves the low bits untouched, then
2365 // we can skip the AND operation
2366 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
2367 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
2368 if( progress != NULL ) return progress;
2369
2370 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
2371 if( progress != NULL ) return progress;
2372
2373 // Finally check the default case
2374 return StoreNode::Ideal(phase, can_reshape);
2375 }
2376
2377 //=============================================================================
2378 //------------------------------Identity---------------------------------------
2379 Node *StoreCMNode::Identity( PhaseTransform *phase ) {
2380 // No need to card mark when storing a null ptr
2381 Node* my_store = in(MemNode::OopStore);
2382 if (my_store->is_Store()) {
2383 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) );
2384 if( t1 == TypePtr::NULL_PTR ) {
2385 return in(MemNode::Memory);
2386 }
2387 }
2388 return this;
2389 }
2390
2391 //=============================================================================
2392 //------------------------------Ideal---------------------------------------
2393 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){
2394 Node* progress = StoreNode::Ideal(phase, can_reshape);
2395 if (progress != NULL) return progress;
2396
2397 Node* my_store = in(MemNode::OopStore);
2398 if (my_store->is_MergeMem()) {
2399 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx());
2400 set_req(MemNode::OopStore, mem);
2401 return this;
2402 }
2403
2404 return NULL;
2405 }
2406
2407 //------------------------------Value-----------------------------------------
2408 const Type *StoreCMNode::Value( PhaseTransform *phase ) const {
2409 // Either input is TOP ==> the result is TOP
2410 const Type *t = phase->type( in(MemNode::Memory) );
2411 if( t == Type::TOP ) return Type::TOP;
2412 t = phase->type( in(MemNode::Address) );
2413 if( t == Type::TOP ) return Type::TOP;
2414 t = phase->type( in(MemNode::ValueIn) );
2415 if( t == Type::TOP ) return Type::TOP;
2416 // If extra input is TOP ==> the result is TOP
2417 t = phase->type( in(MemNode::OopStore) );
2418 if( t == Type::TOP ) return Type::TOP;
2419
2420 return StoreNode::Value( phase );
2421 }
2422
2423
2424 //=============================================================================
2425 //----------------------------------SCMemProjNode------------------------------
2426 const Type * SCMemProjNode::Value( PhaseTransform *phase ) const
2427 {
2428 return bottom_type();
2429 }
2430
2431 //=============================================================================
2432 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : Node(5) {
2433 init_req(MemNode::Control, c );
2434 init_req(MemNode::Memory , mem);
2435 init_req(MemNode::Address, adr);
2436 init_req(MemNode::ValueIn, val);
2437 init_req( ExpectedIn, ex );
2438 init_class_id(Class_LoadStore);
2439
2440 }
2441
2442 //=============================================================================
2443 //-------------------------------adr_type--------------------------------------
2444 // Do we Match on this edge index or not? Do not match memory
2445 const TypePtr* ClearArrayNode::adr_type() const {
2446 Node *adr = in(3);
2447 return MemNode::calculate_adr_type(adr->bottom_type());
2448 }
2449
2450 //------------------------------match_edge-------------------------------------
2451 // Do we Match on this edge index or not? Do not match memory
2452 uint ClearArrayNode::match_edge(uint idx) const {
2453 return idx > 1;
2454 }
2455
2456 //------------------------------Identity---------------------------------------
2457 // Clearing a zero length array does nothing
2458 Node *ClearArrayNode::Identity( PhaseTransform *phase ) {
2459 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
2460 }
2461
2462 //------------------------------Idealize---------------------------------------
2463 // Clearing a short array is faster with stores
2464 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape){
2465 const int unit = BytesPerLong;
2466 const TypeX* t = phase->type(in(2))->isa_intptr_t();
2467 if (!t) return NULL;
2468 if (!t->is_con()) return NULL;
2469 intptr_t raw_count = t->get_con();
2470 intptr_t size = raw_count;
2471 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
2472 // Clearing nothing uses the Identity call.
2473 // Negative clears are possible on dead ClearArrays
2474 // (see jck test stmt114.stmt11402.val).
2475 if (size <= 0 || size % unit != 0) return NULL;
2476 intptr_t count = size / unit;
2477 // Length too long; use fast hardware clear
2478 if (size > Matcher::init_array_short_size) return NULL;
2479 Node *mem = in(1);
2480 if( phase->type(mem)==Type::TOP ) return NULL;
2481 Node *adr = in(3);
2482 const Type* at = phase->type(adr);
2483 if( at==Type::TOP ) return NULL;
2484 const TypePtr* atp = at->isa_ptr();
2485 // adjust atp to be the correct array element address type
2486 if (atp == NULL) atp = TypePtr::BOTTOM;
2487 else atp = atp->add_offset(Type::OffsetBot);
2488 // Get base for derived pointer purposes
2489 if( adr->Opcode() != Op_AddP ) Unimplemented();
2490 Node *base = adr->in(1);
2491
2492 Node *zero = phase->makecon(TypeLong::ZERO);
2493 Node *off = phase->MakeConX(BytesPerLong);
2494 mem = new (phase->C, 4) StoreLNode(in(0),mem,adr,atp,zero);
2495 count--;
2496 while( count-- ) {
2497 mem = phase->transform(mem);
2498 adr = phase->transform(new (phase->C, 4) AddPNode(base,adr,off));
2499 mem = new (phase->C, 4) StoreLNode(in(0),mem,adr,atp,zero);
2500 }
2501 return mem;
2502 }
2503
2504 //----------------------------step_through----------------------------------
2505 // Return allocation input memory edge if it is different instance
2506 // or itself if it is the one we are looking for.
2507 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) {
2508 Node* n = *np;
2509 assert(n->is_ClearArray(), "sanity");
2510 intptr_t offset;
2511 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
2512 // This method is called only before Allocate nodes are expanded during
2513 // macro nodes expansion. Before that ClearArray nodes are only generated
2514 // in LibraryCallKit::generate_arraycopy() which follows allocations.
2515 assert(alloc != NULL, "should have allocation");
2516 if (alloc->_idx == instance_id) {
2517 // Can not bypass initialization of the instance we are looking for.
2518 return false;
2519 }
2520 // Otherwise skip it.
2521 InitializeNode* init = alloc->initialization();
2522 if (init != NULL)
2523 *np = init->in(TypeFunc::Memory);
2524 else
2525 *np = alloc->in(TypeFunc::Memory);
2526 return true;
2527 }
2528
2529 //----------------------------clear_memory-------------------------------------
2530 // Generate code to initialize object storage to zero.
2531 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2532 intptr_t start_offset,
2533 Node* end_offset,
2534 PhaseGVN* phase) {
2535 Compile* C = phase->C;
2536 intptr_t offset = start_offset;
2537
2538 int unit = BytesPerLong;
2539 if ((offset % unit) != 0) {
2540 Node* adr = new (C, 4) AddPNode(dest, dest, phase->MakeConX(offset));
2541 adr = phase->transform(adr);
2542 const TypePtr* atp = TypeRawPtr::BOTTOM;
2543 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT);
2544 mem = phase->transform(mem);
2545 offset += BytesPerInt;
2546 }
2547 assert((offset % unit) == 0, "");
2548
2549 // Initialize the remaining stuff, if any, with a ClearArray.
2550 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase);
2551 }
2552
2553 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2554 Node* start_offset,
2555 Node* end_offset,
2556 PhaseGVN* phase) {
2557 if (start_offset == end_offset) {
2558 // nothing to do
2559 return mem;
2560 }
2561
2562 Compile* C = phase->C;
2563 int unit = BytesPerLong;
2564 Node* zbase = start_offset;
2565 Node* zend = end_offset;
2566
2567 // Scale to the unit required by the CPU:
2568 if (!Matcher::init_array_count_is_in_bytes) {
2569 Node* shift = phase->intcon(exact_log2(unit));
2570 zbase = phase->transform( new(C,3) URShiftXNode(zbase, shift) );
2571 zend = phase->transform( new(C,3) URShiftXNode(zend, shift) );
2572 }
2573
2574 Node* zsize = phase->transform( new(C,3) SubXNode(zend, zbase) );
2575 Node* zinit = phase->zerocon((unit == BytesPerLong) ? T_LONG : T_INT);
2576
2577 // Bulk clear double-words
2578 Node* adr = phase->transform( new(C,4) AddPNode(dest, dest, start_offset) );
2579 mem = new (C, 4) ClearArrayNode(ctl, mem, zsize, adr);
2580 return phase->transform(mem);
2581 }
2582
2583 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2584 intptr_t start_offset,
2585 intptr_t end_offset,
2586 PhaseGVN* phase) {
2587 if (start_offset == end_offset) {
2588 // nothing to do
2589 return mem;
2590 }
2591
2592 Compile* C = phase->C;
2593 assert((end_offset % BytesPerInt) == 0, "odd end offset");
2594 intptr_t done_offset = end_offset;
2595 if ((done_offset % BytesPerLong) != 0) {
2596 done_offset -= BytesPerInt;
2597 }
2598 if (done_offset > start_offset) {
2599 mem = clear_memory(ctl, mem, dest,
2600 start_offset, phase->MakeConX(done_offset), phase);
2601 }
2602 if (done_offset < end_offset) { // emit the final 32-bit store
2603 Node* adr = new (C, 4) AddPNode(dest, dest, phase->MakeConX(done_offset));
2604 adr = phase->transform(adr);
2605 const TypePtr* atp = TypeRawPtr::BOTTOM;
2606 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT);
2607 mem = phase->transform(mem);
2608 done_offset += BytesPerInt;
2609 }
2610 assert(done_offset == end_offset, "");
2611 return mem;
2612 }
2613
2614 //=============================================================================
2615 // Do we match on this edge? No memory edges
2616 uint StrCompNode::match_edge(uint idx) const {
2617 return idx == 2 || idx == 3; // StrComp (Binary str1 cnt1) (Binary str2 cnt2)
2618 }
2619
2620 //------------------------------Ideal------------------------------------------
2621 // Return a node which is more "ideal" than the current node. Strip out
2622 // control copies
2623 Node *StrCompNode::Ideal(PhaseGVN *phase, bool can_reshape){
2624 return remove_dead_region(phase, can_reshape) ? this : NULL;
2625 }
2626
2627 //=============================================================================
2628 // Do we match on this edge? No memory edges
2629 uint StrEqualsNode::match_edge(uint idx) const {
2630 return idx == 2 || idx == 3; // StrEquals (Binary str1 str2) cnt
2631 }
2632
2633 //------------------------------Ideal------------------------------------------
2634 // Return a node which is more "ideal" than the current node. Strip out
2635 // control copies
2636 Node *StrEqualsNode::Ideal(PhaseGVN *phase, bool can_reshape){
2637 return remove_dead_region(phase, can_reshape) ? this : NULL;
2638 }
2639
2640 //=============================================================================
2641 // Do we match on this edge? No memory edges
2642 uint StrIndexOfNode::match_edge(uint idx) const {
2643 return idx == 2 || idx == 3; // StrIndexOf (Binary str1 cnt1) (Binary str2 cnt2)
2644 }
2645
2646 //------------------------------Ideal------------------------------------------
2647 // Return a node which is more "ideal" than the current node. Strip out
2648 // control copies
2649 Node *StrIndexOfNode::Ideal(PhaseGVN *phase, bool can_reshape){
2650 return remove_dead_region(phase, can_reshape) ? this : NULL;
2651 }
2652
2653 //=============================================================================
2654 // Do we match on this edge? No memory edges
2655 uint AryEqNode::match_edge(uint idx) const {
2656 return idx == 2 || idx == 3; // StrEquals ary1 ary2
2657 }
2658 //------------------------------Ideal------------------------------------------
2659 // Return a node which is more "ideal" than the current node. Strip out
2660 // control copies
2661 Node *AryEqNode::Ideal(PhaseGVN *phase, bool can_reshape){
2662 return remove_dead_region(phase, can_reshape) ? this : NULL;
2663 }
2664
2665 //=============================================================================
2666 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
2667 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)),
2668 _adr_type(C->get_adr_type(alias_idx))
2669 {
2670 init_class_id(Class_MemBar);
2671 Node* top = C->top();
2672 init_req(TypeFunc::I_O,top);
2673 init_req(TypeFunc::FramePtr,top);
2674 init_req(TypeFunc::ReturnAdr,top);
2675 if (precedent != NULL)
2676 init_req(TypeFunc::Parms, precedent);
2677 }
2678
2679 //------------------------------cmp--------------------------------------------
2680 uint MemBarNode::hash() const { return NO_HASH; }
2681 uint MemBarNode::cmp( const Node &n ) const {
2682 return (&n == this); // Always fail except on self
2683 }
2684
2685 //------------------------------make-------------------------------------------
2686 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
2687 int len = Precedent + (pn == NULL? 0: 1);
2688 switch (opcode) {
2689 case Op_MemBarAcquire: return new(C, len) MemBarAcquireNode(C, atp, pn);
2690 case Op_MemBarRelease: return new(C, len) MemBarReleaseNode(C, atp, pn);
2691 case Op_MemBarVolatile: return new(C, len) MemBarVolatileNode(C, atp, pn);
2692 case Op_MemBarCPUOrder: return new(C, len) MemBarCPUOrderNode(C, atp, pn);
2693 case Op_Initialize: return new(C, len) InitializeNode(C, atp, pn);
2694 default: ShouldNotReachHere(); return NULL;
2695 }
2696 }
2697
2698 //------------------------------Ideal------------------------------------------
2699 // Return a node which is more "ideal" than the current node. Strip out
2700 // control copies
2701 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2702 if (remove_dead_region(phase, can_reshape)) return this;
2703
2704 // Eliminate volatile MemBars for scalar replaced objects.
2705 if (can_reshape && req() == (Precedent+1) &&
2706 (Opcode() == Op_MemBarAcquire || Opcode() == Op_MemBarVolatile)) {
2707 // Volatile field loads and stores.
2708 Node* my_mem = in(MemBarNode::Precedent);
2709 if (my_mem != NULL && my_mem->is_Mem()) {
2710 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
2711 // Check for scalar replaced object reference.
2712 if( t_oop != NULL && t_oop->is_known_instance_field() &&
2713 t_oop->offset() != Type::OffsetBot &&
2714 t_oop->offset() != Type::OffsetTop) {
2715 // Replace MemBar projections by its inputs.
2716 PhaseIterGVN* igvn = phase->is_IterGVN();
2717 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
2718 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
2719 // Must return either the original node (now dead) or a new node
2720 // (Do not return a top here, since that would break the uniqueness of top.)
2721 return new (phase->C, 1) ConINode(TypeInt::ZERO);
2722 }
2723 }
2724 }
2725 return NULL;
2726 }
2727
2728 //------------------------------Value------------------------------------------
2729 const Type *MemBarNode::Value( PhaseTransform *phase ) const {
2730 if( !in(0) ) return Type::TOP;
2731 if( phase->type(in(0)) == Type::TOP )
2732 return Type::TOP;
2733 return TypeTuple::MEMBAR;
2734 }
2735
2736 //------------------------------match------------------------------------------
2737 // Construct projections for memory.
2738 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) {
2739 switch (proj->_con) {
2740 case TypeFunc::Control:
2741 case TypeFunc::Memory:
2742 return new (m->C, 1) MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
2743 }
2744 ShouldNotReachHere();
2745 return NULL;
2746 }
2747
2748 //===========================InitializeNode====================================
2749 // SUMMARY:
2750 // This node acts as a memory barrier on raw memory, after some raw stores.
2751 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
2752 // The Initialize can 'capture' suitably constrained stores as raw inits.
2753 // It can coalesce related raw stores into larger units (called 'tiles').
2754 // It can avoid zeroing new storage for memory units which have raw inits.
2755 // At macro-expansion, it is marked 'complete', and does not optimize further.
2756 //
2757 // EXAMPLE:
2758 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
2759 // ctl = incoming control; mem* = incoming memory
2760 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
2761 // First allocate uninitialized memory and fill in the header:
2762 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
2763 // ctl := alloc.Control; mem* := alloc.Memory*
2764 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
2765 // Then initialize to zero the non-header parts of the raw memory block:
2766 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
2767 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
2768 // After the initialize node executes, the object is ready for service:
2769 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
2770 // Suppose its body is immediately initialized as {1,2}:
2771 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
2772 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
2773 // mem.SLICE(#short[*]) := store2
2774 //
2775 // DETAILS:
2776 // An InitializeNode collects and isolates object initialization after
2777 // an AllocateNode and before the next possible safepoint. As a
2778 // memory barrier (MemBarNode), it keeps critical stores from drifting
2779 // down past any safepoint or any publication of the allocation.
2780 // Before this barrier, a newly-allocated object may have uninitialized bits.
2781 // After this barrier, it may be treated as a real oop, and GC is allowed.
2782 //
2783 // The semantics of the InitializeNode include an implicit zeroing of
2784 // the new object from object header to the end of the object.
2785 // (The object header and end are determined by the AllocateNode.)
2786 //
2787 // Certain stores may be added as direct inputs to the InitializeNode.
2788 // These stores must update raw memory, and they must be to addresses
2789 // derived from the raw address produced by AllocateNode, and with
2790 // a constant offset. They must be ordered by increasing offset.
2791 // The first one is at in(RawStores), the last at in(req()-1).
2792 // Unlike most memory operations, they are not linked in a chain,
2793 // but are displayed in parallel as users of the rawmem output of
2794 // the allocation.
2795 //
2796 // (See comments in InitializeNode::capture_store, which continue
2797 // the example given above.)
2798 //
2799 // When the associated Allocate is macro-expanded, the InitializeNode
2800 // may be rewritten to optimize collected stores. A ClearArrayNode
2801 // may also be created at that point to represent any required zeroing.
2802 // The InitializeNode is then marked 'complete', prohibiting further
2803 // capturing of nearby memory operations.
2804 //
2805 // During macro-expansion, all captured initializations which store
2806 // constant values of 32 bits or smaller are coalesced (if advantageous)
2807 // into larger 'tiles' 32 or 64 bits. This allows an object to be
2808 // initialized in fewer memory operations. Memory words which are
2809 // covered by neither tiles nor non-constant stores are pre-zeroed
2810 // by explicit stores of zero. (The code shape happens to do all
2811 // zeroing first, then all other stores, with both sequences occurring
2812 // in order of ascending offsets.)
2813 //
2814 // Alternatively, code may be inserted between an AllocateNode and its
2815 // InitializeNode, to perform arbitrary initialization of the new object.
2816 // E.g., the object copying intrinsics insert complex data transfers here.
2817 // The initialization must then be marked as 'complete' disable the
2818 // built-in zeroing semantics and the collection of initializing stores.
2819 //
2820 // While an InitializeNode is incomplete, reads from the memory state
2821 // produced by it are optimizable if they match the control edge and
2822 // new oop address associated with the allocation/initialization.
2823 // They return a stored value (if the offset matches) or else zero.
2824 // A write to the memory state, if it matches control and address,
2825 // and if it is to a constant offset, may be 'captured' by the
2826 // InitializeNode. It is cloned as a raw memory operation and rewired
2827 // inside the initialization, to the raw oop produced by the allocation.
2828 // Operations on addresses which are provably distinct (e.g., to
2829 // other AllocateNodes) are allowed to bypass the initialization.
2830 //
2831 // The effect of all this is to consolidate object initialization
2832 // (both arrays and non-arrays, both piecewise and bulk) into a
2833 // single location, where it can be optimized as a unit.
2834 //
2835 // Only stores with an offset less than TrackedInitializationLimit words
2836 // will be considered for capture by an InitializeNode. This puts a
2837 // reasonable limit on the complexity of optimized initializations.
2838
2839 //---------------------------InitializeNode------------------------------------
2840 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
2841 : _is_complete(false),
2842 MemBarNode(C, adr_type, rawoop)
2843 {
2844 init_class_id(Class_Initialize);
2845
2846 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
2847 assert(in(RawAddress) == rawoop, "proper init");
2848 // Note: allocation() can be NULL, for secondary initialization barriers
2849 }
2850
2851 // Since this node is not matched, it will be processed by the
2852 // register allocator. Declare that there are no constraints
2853 // on the allocation of the RawAddress edge.
2854 const RegMask &InitializeNode::in_RegMask(uint idx) const {
2855 // This edge should be set to top, by the set_complete. But be conservative.
2856 if (idx == InitializeNode::RawAddress)
2857 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
2858 return RegMask::Empty;
2859 }
2860
2861 Node* InitializeNode::memory(uint alias_idx) {
2862 Node* mem = in(Memory);
2863 if (mem->is_MergeMem()) {
2864 return mem->as_MergeMem()->memory_at(alias_idx);
2865 } else {
2866 // incoming raw memory is not split
2867 return mem;
2868 }
2869 }
2870
2871 bool InitializeNode::is_non_zero() {
2872 if (is_complete()) return false;
2873 remove_extra_zeroes();
2874 return (req() > RawStores);
2875 }
2876
2877 void InitializeNode::set_complete(PhaseGVN* phase) {
2878 assert(!is_complete(), "caller responsibility");
2879 _is_complete = true;
2880
2881 // After this node is complete, it contains a bunch of
2882 // raw-memory initializations. There is no need for
2883 // it to have anything to do with non-raw memory effects.
2884 // Therefore, tell all non-raw users to re-optimize themselves,
2885 // after skipping the memory effects of this initialization.
2886 PhaseIterGVN* igvn = phase->is_IterGVN();
2887 if (igvn) igvn->add_users_to_worklist(this);
2888 }
2889
2890 // convenience function
2891 // return false if the init contains any stores already
2892 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
2893 InitializeNode* init = initialization();
2894 if (init == NULL || init->is_complete()) return false;
2895 init->remove_extra_zeroes();
2896 // for now, if this allocation has already collected any inits, bail:
2897 if (init->is_non_zero()) return false;
2898 init->set_complete(phase);
2899 return true;
2900 }
2901
2902 void InitializeNode::remove_extra_zeroes() {
2903 if (req() == RawStores) return;
2904 Node* zmem = zero_memory();
2905 uint fill = RawStores;
2906 for (uint i = fill; i < req(); i++) {
2907 Node* n = in(i);
2908 if (n->is_top() || n == zmem) continue; // skip
2909 if (fill < i) set_req(fill, n); // compact
2910 ++fill;
2911 }
2912 // delete any empty spaces created:
2913 while (fill < req()) {
2914 del_req(fill);
2915 }
2916 }
2917
2918 // Helper for remembering which stores go with which offsets.
2919 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) {
2920 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
2921 intptr_t offset = -1;
2922 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
2923 phase, offset);
2924 if (base == NULL) return -1; // something is dead,
2925 if (offset < 0) return -1; // dead, dead
2926 return offset;
2927 }
2928
2929 // Helper for proving that an initialization expression is
2930 // "simple enough" to be folded into an object initialization.
2931 // Attempts to prove that a store's initial value 'n' can be captured
2932 // within the initialization without creating a vicious cycle, such as:
2933 // { Foo p = new Foo(); p.next = p; }
2934 // True for constants and parameters and small combinations thereof.
2935 bool InitializeNode::detect_init_independence(Node* n,
2936 bool st_is_pinned,
2937 int& count) {
2938 if (n == NULL) return true; // (can this really happen?)
2939 if (n->is_Proj()) n = n->in(0);
2940 if (n == this) return false; // found a cycle
2941 if (n->is_Con()) return true;
2942 if (n->is_Start()) return true; // params, etc., are OK
2943 if (n->is_Root()) return true; // even better
2944
2945 Node* ctl = n->in(0);
2946 if (ctl != NULL && !ctl->is_top()) {
2947 if (ctl->is_Proj()) ctl = ctl->in(0);
2948 if (ctl == this) return false;
2949
2950 // If we already know that the enclosing memory op is pinned right after
2951 // the init, then any control flow that the store has picked up
2952 // must have preceded the init, or else be equal to the init.
2953 // Even after loop optimizations (which might change control edges)
2954 // a store is never pinned *before* the availability of its inputs.
2955 if (!MemNode::all_controls_dominate(n, this))
2956 return false; // failed to prove a good control
2957
2958 }
2959
2960 // Check data edges for possible dependencies on 'this'.
2961 if ((count += 1) > 20) return false; // complexity limit
2962 for (uint i = 1; i < n->req(); i++) {
2963 Node* m = n->in(i);
2964 if (m == NULL || m == n || m->is_top()) continue;
2965 uint first_i = n->find_edge(m);
2966 if (i != first_i) continue; // process duplicate edge just once
2967 if (!detect_init_independence(m, st_is_pinned, count)) {
2968 return false;
2969 }
2970 }
2971
2972 return true;
2973 }
2974
2975 // Here are all the checks a Store must pass before it can be moved into
2976 // an initialization. Returns zero if a check fails.
2977 // On success, returns the (constant) offset to which the store applies,
2978 // within the initialized memory.
2979 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase) {
2980 const int FAIL = 0;
2981 if (st->req() != MemNode::ValueIn + 1)
2982 return FAIL; // an inscrutable StoreNode (card mark?)
2983 Node* ctl = st->in(MemNode::Control);
2984 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this))
2985 return FAIL; // must be unconditional after the initialization
2986 Node* mem = st->in(MemNode::Memory);
2987 if (!(mem->is_Proj() && mem->in(0) == this))
2988 return FAIL; // must not be preceded by other stores
2989 Node* adr = st->in(MemNode::Address);
2990 intptr_t offset;
2991 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
2992 if (alloc == NULL)
2993 return FAIL; // inscrutable address
2994 if (alloc != allocation())
2995 return FAIL; // wrong allocation! (store needs to float up)
2996 Node* val = st->in(MemNode::ValueIn);
2997 int complexity_count = 0;
2998 if (!detect_init_independence(val, true, complexity_count))
2999 return FAIL; // stored value must be 'simple enough'
3000
3001 return offset; // success
3002 }
3003
3004 // Find the captured store in(i) which corresponds to the range
3005 // [start..start+size) in the initialized object.
3006 // If there is one, return its index i. If there isn't, return the
3007 // negative of the index where it should be inserted.
3008 // Return 0 if the queried range overlaps an initialization boundary
3009 // or if dead code is encountered.
3010 // If size_in_bytes is zero, do not bother with overlap checks.
3011 int InitializeNode::captured_store_insertion_point(intptr_t start,
3012 int size_in_bytes,
3013 PhaseTransform* phase) {
3014 const int FAIL = 0, MAX_STORE = BytesPerLong;
3015
3016 if (is_complete())
3017 return FAIL; // arraycopy got here first; punt
3018
3019 assert(allocation() != NULL, "must be present");
3020
3021 // no negatives, no header fields:
3022 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
3023
3024 // after a certain size, we bail out on tracking all the stores:
3025 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3026 if (start >= ti_limit) return FAIL;
3027
3028 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
3029 if (i >= limit) return -(int)i; // not found; here is where to put it
3030
3031 Node* st = in(i);
3032 intptr_t st_off = get_store_offset(st, phase);
3033 if (st_off < 0) {
3034 if (st != zero_memory()) {
3035 return FAIL; // bail out if there is dead garbage
3036 }
3037 } else if (st_off > start) {
3038 // ...we are done, since stores are ordered
3039 if (st_off < start + size_in_bytes) {
3040 return FAIL; // the next store overlaps
3041 }
3042 return -(int)i; // not found; here is where to put it
3043 } else if (st_off < start) {
3044 if (size_in_bytes != 0 &&
3045 start < st_off + MAX_STORE &&
3046 start < st_off + st->as_Store()->memory_size()) {
3047 return FAIL; // the previous store overlaps
3048 }
3049 } else {
3050 if (size_in_bytes != 0 &&
3051 st->as_Store()->memory_size() != size_in_bytes) {
3052 return FAIL; // mismatched store size
3053 }
3054 return i;
3055 }
3056
3057 ++i;
3058 }
3059 }
3060
3061 // Look for a captured store which initializes at the offset 'start'
3062 // with the given size. If there is no such store, and no other
3063 // initialization interferes, then return zero_memory (the memory
3064 // projection of the AllocateNode).
3065 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
3066 PhaseTransform* phase) {
3067 assert(stores_are_sane(phase), "");
3068 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3069 if (i == 0) {
3070 return NULL; // something is dead
3071 } else if (i < 0) {
3072 return zero_memory(); // just primordial zero bits here
3073 } else {
3074 Node* st = in(i); // here is the store at this position
3075 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
3076 return st;
3077 }
3078 }
3079
3080 // Create, as a raw pointer, an address within my new object at 'offset'.
3081 Node* InitializeNode::make_raw_address(intptr_t offset,
3082 PhaseTransform* phase) {
3083 Node* addr = in(RawAddress);
3084 if (offset != 0) {
3085 Compile* C = phase->C;
3086 addr = phase->transform( new (C, 4) AddPNode(C->top(), addr,
3087 phase->MakeConX(offset)) );
3088 }
3089 return addr;
3090 }
3091
3092 // Clone the given store, converting it into a raw store
3093 // initializing a field or element of my new object.
3094 // Caller is responsible for retiring the original store,
3095 // with subsume_node or the like.
3096 //
3097 // From the example above InitializeNode::InitializeNode,
3098 // here are the old stores to be captured:
3099 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3100 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3101 //
3102 // Here is the changed code; note the extra edges on init:
3103 // alloc = (Allocate ...)
3104 // rawoop = alloc.RawAddress
3105 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
3106 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
3107 // init = (Initialize alloc.Control alloc.Memory rawoop
3108 // rawstore1 rawstore2)
3109 //
3110 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
3111 PhaseTransform* phase) {
3112 assert(stores_are_sane(phase), "");
3113
3114 if (start < 0) return NULL;
3115 assert(can_capture_store(st, phase) == start, "sanity");
3116
3117 Compile* C = phase->C;
3118 int size_in_bytes = st->memory_size();
3119 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3120 if (i == 0) return NULL; // bail out
3121 Node* prev_mem = NULL; // raw memory for the captured store
3122 if (i > 0) {
3123 prev_mem = in(i); // there is a pre-existing store under this one
3124 set_req(i, C->top()); // temporarily disconnect it
3125 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
3126 } else {
3127 i = -i; // no pre-existing store
3128 prev_mem = zero_memory(); // a slice of the newly allocated object
3129 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
3130 set_req(--i, C->top()); // reuse this edge; it has been folded away
3131 else
3132 ins_req(i, C->top()); // build a new edge
3133 }
3134 Node* new_st = st->clone();
3135 new_st->set_req(MemNode::Control, in(Control));
3136 new_st->set_req(MemNode::Memory, prev_mem);
3137 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
3138 new_st = phase->transform(new_st);
3139
3140 // At this point, new_st might have swallowed a pre-existing store
3141 // at the same offset, or perhaps new_st might have disappeared,
3142 // if it redundantly stored the same value (or zero to fresh memory).
3143
3144 // In any case, wire it in:
3145 set_req(i, new_st);
3146
3147 // The caller may now kill the old guy.
3148 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
3149 assert(check_st == new_st || check_st == NULL, "must be findable");
3150 assert(!is_complete(), "");
3151 return new_st;
3152 }
3153
3154 static bool store_constant(jlong* tiles, int num_tiles,
3155 intptr_t st_off, int st_size,
3156 jlong con) {
3157 if ((st_off & (st_size-1)) != 0)
3158 return false; // strange store offset (assume size==2**N)
3159 address addr = (address)tiles + st_off;
3160 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
3161 switch (st_size) {
3162 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
3163 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
3164 case sizeof(jint): *(jint*) addr = (jint) con; break;
3165 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
3166 default: return false; // strange store size (detect size!=2**N here)
3167 }
3168 return true; // return success to caller
3169 }
3170
3171 // Coalesce subword constants into int constants and possibly
3172 // into long constants. The goal, if the CPU permits,
3173 // is to initialize the object with a small number of 64-bit tiles.
3174 // Also, convert floating-point constants to bit patterns.
3175 // Non-constants are not relevant to this pass.
3176 //
3177 // In terms of the running example on InitializeNode::InitializeNode
3178 // and InitializeNode::capture_store, here is the transformation
3179 // of rawstore1 and rawstore2 into rawstore12:
3180 // alloc = (Allocate ...)
3181 // rawoop = alloc.RawAddress
3182 // tile12 = 0x00010002
3183 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
3184 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
3185 //
3186 void
3187 InitializeNode::coalesce_subword_stores(intptr_t header_size,
3188 Node* size_in_bytes,
3189 PhaseGVN* phase) {
3190 Compile* C = phase->C;
3191
3192 assert(stores_are_sane(phase), "");
3193 // Note: After this pass, they are not completely sane,
3194 // since there may be some overlaps.
3195
3196 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
3197
3198 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3199 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
3200 size_limit = MIN2(size_limit, ti_limit);
3201 size_limit = align_size_up(size_limit, BytesPerLong);
3202 int num_tiles = size_limit / BytesPerLong;
3203
3204 // allocate space for the tile map:
3205 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
3206 jlong tiles_buf[small_len];
3207 Node* nodes_buf[small_len];
3208 jlong inits_buf[small_len];
3209 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
3210 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3211 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
3212 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
3213 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
3214 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3215 // tiles: exact bitwise model of all primitive constants
3216 // nodes: last constant-storing node subsumed into the tiles model
3217 // inits: which bytes (in each tile) are touched by any initializations
3218
3219 //// Pass A: Fill in the tile model with any relevant stores.
3220
3221 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
3222 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
3223 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
3224 Node* zmem = zero_memory(); // initially zero memory state
3225 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3226 Node* st = in(i);
3227 intptr_t st_off = get_store_offset(st, phase);
3228
3229 // Figure out the store's offset and constant value:
3230 if (st_off < header_size) continue; //skip (ignore header)
3231 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
3232 int st_size = st->as_Store()->memory_size();
3233 if (st_off + st_size > size_limit) break;
3234
3235 // Record which bytes are touched, whether by constant or not.
3236 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
3237 continue; // skip (strange store size)
3238
3239 const Type* val = phase->type(st->in(MemNode::ValueIn));
3240 if (!val->singleton()) continue; //skip (non-con store)
3241 BasicType type = val->basic_type();
3242
3243 jlong con = 0;
3244 switch (type) {
3245 case T_INT: con = val->is_int()->get_con(); break;
3246 case T_LONG: con = val->is_long()->get_con(); break;
3247 case T_FLOAT: con = jint_cast(val->getf()); break;
3248 case T_DOUBLE: con = jlong_cast(val->getd()); break;
3249 default: continue; //skip (odd store type)
3250 }
3251
3252 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
3253 st->Opcode() == Op_StoreL) {
3254 continue; // This StoreL is already optimal.
3255 }
3256
3257 // Store down the constant.
3258 store_constant(tiles, num_tiles, st_off, st_size, con);
3259
3260 intptr_t j = st_off >> LogBytesPerLong;
3261
3262 if (type == T_INT && st_size == BytesPerInt
3263 && (st_off & BytesPerInt) == BytesPerInt) {
3264 jlong lcon = tiles[j];
3265 if (!Matcher::isSimpleConstant64(lcon) &&
3266 st->Opcode() == Op_StoreI) {
3267 // This StoreI is already optimal by itself.
3268 jint* intcon = (jint*) &tiles[j];
3269 intcon[1] = 0; // undo the store_constant()
3270
3271 // If the previous store is also optimal by itself, back up and
3272 // undo the action of the previous loop iteration... if we can.
3273 // But if we can't, just let the previous half take care of itself.
3274 st = nodes[j];
3275 st_off -= BytesPerInt;
3276 con = intcon[0];
3277 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) {
3278 assert(st_off >= header_size, "still ignoring header");
3279 assert(get_store_offset(st, phase) == st_off, "must be");
3280 assert(in(i-1) == zmem, "must be");
3281 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
3282 assert(con == tcon->is_int()->get_con(), "must be");
3283 // Undo the effects of the previous loop trip, which swallowed st:
3284 intcon[0] = 0; // undo store_constant()
3285 set_req(i-1, st); // undo set_req(i, zmem)
3286 nodes[j] = NULL; // undo nodes[j] = st
3287 --old_subword; // undo ++old_subword
3288 }
3289 continue; // This StoreI is already optimal.
3290 }
3291 }
3292
3293 // This store is not needed.
3294 set_req(i, zmem);
3295 nodes[j] = st; // record for the moment
3296 if (st_size < BytesPerLong) // something has changed
3297 ++old_subword; // includes int/float, but who's counting...
3298 else ++old_long;
3299 }
3300
3301 if ((old_subword + old_long) == 0)
3302 return; // nothing more to do
3303
3304 //// Pass B: Convert any non-zero tiles into optimal constant stores.
3305 // Be sure to insert them before overlapping non-constant stores.
3306 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
3307 for (int j = 0; j < num_tiles; j++) {
3308 jlong con = tiles[j];
3309 jlong init = inits[j];
3310 if (con == 0) continue;
3311 jint con0, con1; // split the constant, address-wise
3312 jint init0, init1; // split the init map, address-wise
3313 { union { jlong con; jint intcon[2]; } u;
3314 u.con = con;
3315 con0 = u.intcon[0];
3316 con1 = u.intcon[1];
3317 u.con = init;
3318 init0 = u.intcon[0];
3319 init1 = u.intcon[1];
3320 }
3321
3322 Node* old = nodes[j];
3323 assert(old != NULL, "need the prior store");
3324 intptr_t offset = (j * BytesPerLong);
3325
3326 bool split = !Matcher::isSimpleConstant64(con);
3327
3328 if (offset < header_size) {
3329 assert(offset + BytesPerInt >= header_size, "second int counts");
3330 assert(*(jint*)&tiles[j] == 0, "junk in header");
3331 split = true; // only the second word counts
3332 // Example: int a[] = { 42 ... }
3333 } else if (con0 == 0 && init0 == -1) {
3334 split = true; // first word is covered by full inits
3335 // Example: int a[] = { ... foo(), 42 ... }
3336 } else if (con1 == 0 && init1 == -1) {
3337 split = true; // second word is covered by full inits
3338 // Example: int a[] = { ... 42, foo() ... }
3339 }
3340
3341 // Here's a case where init0 is neither 0 nor -1:
3342 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
3343 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
3344 // In this case the tile is not split; it is (jlong)42.
3345 // The big tile is stored down, and then the foo() value is inserted.
3346 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
3347
3348 Node* ctl = old->in(MemNode::Control);
3349 Node* adr = make_raw_address(offset, phase);
3350 const TypePtr* atp = TypeRawPtr::BOTTOM;
3351
3352 // One or two coalesced stores to plop down.
3353 Node* st[2];
3354 intptr_t off[2];
3355 int nst = 0;
3356 if (!split) {
3357 ++new_long;
3358 off[nst] = offset;
3359 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3360 phase->longcon(con), T_LONG);
3361 } else {
3362 // Omit either if it is a zero.
3363 if (con0 != 0) {
3364 ++new_int;
3365 off[nst] = offset;
3366 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3367 phase->intcon(con0), T_INT);
3368 }
3369 if (con1 != 0) {
3370 ++new_int;
3371 offset += BytesPerInt;
3372 adr = make_raw_address(offset, phase);
3373 off[nst] = offset;
3374 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3375 phase->intcon(con1), T_INT);
3376 }
3377 }
3378
3379 // Insert second store first, then the first before the second.
3380 // Insert each one just before any overlapping non-constant stores.
3381 while (nst > 0) {
3382 Node* st1 = st[--nst];
3383 C->copy_node_notes_to(st1, old);
3384 st1 = phase->transform(st1);
3385 offset = off[nst];
3386 assert(offset >= header_size, "do not smash header");
3387 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
3388 guarantee(ins_idx != 0, "must re-insert constant store");
3389 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
3390 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
3391 set_req(--ins_idx, st1);
3392 else
3393 ins_req(ins_idx, st1);
3394 }
3395 }
3396
3397 if (PrintCompilation && WizardMode)
3398 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
3399 old_subword, old_long, new_int, new_long);
3400 if (C->log() != NULL)
3401 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
3402 old_subword, old_long, new_int, new_long);
3403
3404 // Clean up any remaining occurrences of zmem:
3405 remove_extra_zeroes();
3406 }
3407
3408 // Explore forward from in(start) to find the first fully initialized
3409 // word, and return its offset. Skip groups of subword stores which
3410 // together initialize full words. If in(start) is itself part of a
3411 // fully initialized word, return the offset of in(start). If there
3412 // are no following full-word stores, or if something is fishy, return
3413 // a negative value.
3414 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
3415 int int_map = 0;
3416 intptr_t int_map_off = 0;
3417 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
3418
3419 for (uint i = start, limit = req(); i < limit; i++) {
3420 Node* st = in(i);
3421
3422 intptr_t st_off = get_store_offset(st, phase);
3423 if (st_off < 0) break; // return conservative answer
3424
3425 int st_size = st->as_Store()->memory_size();
3426 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
3427 return st_off; // we found a complete word init
3428 }
3429
3430 // update the map:
3431
3432 intptr_t this_int_off = align_size_down(st_off, BytesPerInt);
3433 if (this_int_off != int_map_off) {
3434 // reset the map:
3435 int_map = 0;
3436 int_map_off = this_int_off;
3437 }
3438
3439 int subword_off = st_off - this_int_off;
3440 int_map |= right_n_bits(st_size) << subword_off;
3441 if ((int_map & FULL_MAP) == FULL_MAP) {
3442 return this_int_off; // we found a complete word init
3443 }
3444
3445 // Did this store hit or cross the word boundary?
3446 intptr_t next_int_off = align_size_down(st_off + st_size, BytesPerInt);
3447 if (next_int_off == this_int_off + BytesPerInt) {
3448 // We passed the current int, without fully initializing it.
3449 int_map_off = next_int_off;
3450 int_map >>= BytesPerInt;
3451 } else if (next_int_off > this_int_off + BytesPerInt) {
3452 // We passed the current and next int.
3453 return this_int_off + BytesPerInt;
3454 }
3455 }
3456
3457 return -1;
3458 }
3459
3460
3461 // Called when the associated AllocateNode is expanded into CFG.
3462 // At this point, we may perform additional optimizations.
3463 // Linearize the stores by ascending offset, to make memory
3464 // activity as coherent as possible.
3465 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
3466 intptr_t header_size,
3467 Node* size_in_bytes,
3468 PhaseGVN* phase) {
3469 assert(!is_complete(), "not already complete");
3470 assert(stores_are_sane(phase), "");
3471 assert(allocation() != NULL, "must be present");
3472
3473 remove_extra_zeroes();
3474
3475 if (ReduceFieldZeroing || ReduceBulkZeroing)
3476 // reduce instruction count for common initialization patterns
3477 coalesce_subword_stores(header_size, size_in_bytes, phase);
3478
3479 Node* zmem = zero_memory(); // initially zero memory state
3480 Node* inits = zmem; // accumulating a linearized chain of inits
3481 #ifdef ASSERT
3482 intptr_t first_offset = allocation()->minimum_header_size();
3483 intptr_t last_init_off = first_offset; // previous init offset
3484 intptr_t last_init_end = first_offset; // previous init offset+size
3485 intptr_t last_tile_end = first_offset; // previous tile offset+size
3486 #endif
3487 intptr_t zeroes_done = header_size;
3488
3489 bool do_zeroing = true; // we might give up if inits are very sparse
3490 int big_init_gaps = 0; // how many large gaps have we seen?
3491
3492 if (ZeroTLAB) do_zeroing = false;
3493 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
3494
3495 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3496 Node* st = in(i);
3497 intptr_t st_off = get_store_offset(st, phase);
3498 if (st_off < 0)
3499 break; // unknown junk in the inits
3500 if (st->in(MemNode::Memory) != zmem)
3501 break; // complicated store chains somehow in list
3502
3503 int st_size = st->as_Store()->memory_size();
3504 intptr_t next_init_off = st_off + st_size;
3505
3506 if (do_zeroing && zeroes_done < next_init_off) {
3507 // See if this store needs a zero before it or under it.
3508 intptr_t zeroes_needed = st_off;
3509
3510 if (st_size < BytesPerInt) {
3511 // Look for subword stores which only partially initialize words.
3512 // If we find some, we must lay down some word-level zeroes first,
3513 // underneath the subword stores.
3514 //
3515 // Examples:
3516 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
3517 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
3518 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
3519 //
3520 // Note: coalesce_subword_stores may have already done this,
3521 // if it was prompted by constant non-zero subword initializers.
3522 // But this case can still arise with non-constant stores.
3523
3524 intptr_t next_full_store = find_next_fullword_store(i, phase);
3525
3526 // In the examples above:
3527 // in(i) p q r s x y z
3528 // st_off 12 13 14 15 12 13 14
3529 // st_size 1 1 1 1 1 1 1
3530 // next_full_s. 12 16 16 16 16 16 16
3531 // z's_done 12 16 16 16 12 16 12
3532 // z's_needed 12 16 16 16 16 16 16
3533 // zsize 0 0 0 0 4 0 4
3534 if (next_full_store < 0) {
3535 // Conservative tack: Zero to end of current word.
3536 zeroes_needed = align_size_up(zeroes_needed, BytesPerInt);
3537 } else {
3538 // Zero to beginning of next fully initialized word.
3539 // Or, don't zero at all, if we are already in that word.
3540 assert(next_full_store >= zeroes_needed, "must go forward");
3541 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
3542 zeroes_needed = next_full_store;
3543 }
3544 }
3545
3546 if (zeroes_needed > zeroes_done) {
3547 intptr_t zsize = zeroes_needed - zeroes_done;
3548 // Do some incremental zeroing on rawmem, in parallel with inits.
3549 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3550 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3551 zeroes_done, zeroes_needed,
3552 phase);
3553 zeroes_done = zeroes_needed;
3554 if (zsize > Matcher::init_array_short_size && ++big_init_gaps > 2)
3555 do_zeroing = false; // leave the hole, next time
3556 }
3557 }
3558
3559 // Collect the store and move on:
3560 st->set_req(MemNode::Memory, inits);
3561 inits = st; // put it on the linearized chain
3562 set_req(i, zmem); // unhook from previous position
3563
3564 if (zeroes_done == st_off)
3565 zeroes_done = next_init_off;
3566
3567 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
3568
3569 #ifdef ASSERT
3570 // Various order invariants. Weaker than stores_are_sane because
3571 // a large constant tile can be filled in by smaller non-constant stores.
3572 assert(st_off >= last_init_off, "inits do not reverse");
3573 last_init_off = st_off;
3574 const Type* val = NULL;
3575 if (st_size >= BytesPerInt &&
3576 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
3577 (int)val->basic_type() < (int)T_OBJECT) {
3578 assert(st_off >= last_tile_end, "tiles do not overlap");
3579 assert(st_off >= last_init_end, "tiles do not overwrite inits");
3580 last_tile_end = MAX2(last_tile_end, next_init_off);
3581 } else {
3582 intptr_t st_tile_end = align_size_up(next_init_off, BytesPerLong);
3583 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
3584 assert(st_off >= last_init_end, "inits do not overlap");
3585 last_init_end = next_init_off; // it's a non-tile
3586 }
3587 #endif //ASSERT
3588 }
3589
3590 remove_extra_zeroes(); // clear out all the zmems left over
3591 add_req(inits);
3592
3593 if (!ZeroTLAB) {
3594 // If anything remains to be zeroed, zero it all now.
3595 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3596 // if it is the last unused 4 bytes of an instance, forget about it
3597 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
3598 if (zeroes_done + BytesPerLong >= size_limit) {
3599 assert(allocation() != NULL, "");
3600 Node* klass_node = allocation()->in(AllocateNode::KlassNode);
3601 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass();
3602 if (zeroes_done == k->layout_helper())
3603 zeroes_done = size_limit;
3604 }
3605 if (zeroes_done < size_limit) {
3606 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3607 zeroes_done, size_in_bytes, phase);
3608 }
3609 }
3610
3611 set_complete(phase);
3612 return rawmem;
3613 }
3614
3615
3616 #ifdef ASSERT
3617 bool InitializeNode::stores_are_sane(PhaseTransform* phase) {
3618 if (is_complete())
3619 return true; // stores could be anything at this point
3620 assert(allocation() != NULL, "must be present");
3621 intptr_t last_off = allocation()->minimum_header_size();
3622 for (uint i = InitializeNode::RawStores; i < req(); i++) {
3623 Node* st = in(i);
3624 intptr_t st_off = get_store_offset(st, phase);
3625 if (st_off < 0) continue; // ignore dead garbage
3626 if (last_off > st_off) {
3627 tty->print_cr("*** bad store offset at %d: %d > %d", i, last_off, st_off);
3628 this->dump(2);
3629 assert(false, "ascending store offsets");
3630 return false;
3631 }
3632 last_off = st_off + st->as_Store()->memory_size();
3633 }
3634 return true;
3635 }
3636 #endif //ASSERT
3637
3638
3639
3640
3641 //============================MergeMemNode=====================================
3642 //
3643 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
3644 // contributing store or call operations. Each contributor provides the memory
3645 // state for a particular "alias type" (see Compile::alias_type). For example,
3646 // if a MergeMem has an input X for alias category #6, then any memory reference
3647 // to alias category #6 may use X as its memory state input, as an exact equivalent
3648 // to using the MergeMem as a whole.
3649 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
3650 //
3651 // (Here, the <N> notation gives the index of the relevant adr_type.)
3652 //
3653 // In one special case (and more cases in the future), alias categories overlap.
3654 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
3655 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
3656 // it is exactly equivalent to that state W:
3657 // MergeMem(<Bot>: W) <==> W
3658 //
3659 // Usually, the merge has more than one input. In that case, where inputs
3660 // overlap (i.e., one is Bot), the narrower alias type determines the memory
3661 // state for that type, and the wider alias type (Bot) fills in everywhere else:
3662 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
3663 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
3664 //
3665 // A merge can take a "wide" memory state as one of its narrow inputs.
3666 // This simply means that the merge observes out only the relevant parts of
3667 // the wide input. That is, wide memory states arriving at narrow merge inputs
3668 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
3669 //
3670 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
3671 // and that memory slices "leak through":
3672 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
3673 //
3674 // But, in such a cascade, repeated memory slices can "block the leak":
3675 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
3676 //
3677 // In the last example, Y is not part of the combined memory state of the
3678 // outermost MergeMem. The system must, of course, prevent unschedulable
3679 // memory states from arising, so you can be sure that the state Y is somehow
3680 // a precursor to state Y'.
3681 //
3682 //
3683 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
3684 // of each MergeMemNode array are exactly the numerical alias indexes, including
3685 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
3686 // Compile::alias_type (and kin) produce and manage these indexes.
3687 //
3688 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
3689 // (Note that this provides quick access to the top node inside MergeMem methods,
3690 // without the need to reach out via TLS to Compile::current.)
3691 //
3692 // As a consequence of what was just described, a MergeMem that represents a full
3693 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
3694 // containing all alias categories.
3695 //
3696 // MergeMem nodes never (?) have control inputs, so in(0) is NULL.
3697 //
3698 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
3699 // a memory state for the alias type <N>, or else the top node, meaning that
3700 // there is no particular input for that alias type. Note that the length of
3701 // a MergeMem is variable, and may be extended at any time to accommodate new
3702 // memory states at larger alias indexes. When merges grow, they are of course
3703 // filled with "top" in the unused in() positions.
3704 //
3705 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
3706 // (Top was chosen because it works smoothly with passes like GCM.)
3707 //
3708 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
3709 // the type of random VM bits like TLS references.) Since it is always the
3710 // first non-Bot memory slice, some low-level loops use it to initialize an
3711 // index variable: for (i = AliasIdxRaw; i < req(); i++).
3712 //
3713 //
3714 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
3715 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
3716 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
3717 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
3718 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
3719 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
3720 //
3721 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
3722 // really that different from the other memory inputs. An abbreviation called
3723 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
3724 //
3725 //
3726 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
3727 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
3728 // that "emerges though" the base memory will be marked as excluding the alias types
3729 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
3730 //
3731 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
3732 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
3733 //
3734 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
3735 // (It is currently unimplemented.) As you can see, the resulting merge is
3736 // actually a disjoint union of memory states, rather than an overlay.
3737 //
3738
3739 //------------------------------MergeMemNode-----------------------------------
3740 Node* MergeMemNode::make_empty_memory() {
3741 Node* empty_memory = (Node*) Compile::current()->top();
3742 assert(empty_memory->is_top(), "correct sentinel identity");
3743 return empty_memory;
3744 }
3745
3746 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
3747 init_class_id(Class_MergeMem);
3748 // all inputs are nullified in Node::Node(int)
3749 // set_input(0, NULL); // no control input
3750
3751 // Initialize the edges uniformly to top, for starters.
3752 Node* empty_mem = make_empty_memory();
3753 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
3754 init_req(i,empty_mem);
3755 }
3756 assert(empty_memory() == empty_mem, "");
3757
3758 if( new_base != NULL && new_base->is_MergeMem() ) {
3759 MergeMemNode* mdef = new_base->as_MergeMem();
3760 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
3761 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
3762 mms.set_memory(mms.memory2());
3763 }
3764 assert(base_memory() == mdef->base_memory(), "");
3765 } else {
3766 set_base_memory(new_base);
3767 }
3768 }
3769
3770 // Make a new, untransformed MergeMem with the same base as 'mem'.
3771 // If mem is itself a MergeMem, populate the result with the same edges.
3772 MergeMemNode* MergeMemNode::make(Compile* C, Node* mem) {
3773 return new(C, 1+Compile::AliasIdxRaw) MergeMemNode(mem);
3774 }
3775
3776 //------------------------------cmp--------------------------------------------
3777 uint MergeMemNode::hash() const { return NO_HASH; }
3778 uint MergeMemNode::cmp( const Node &n ) const {
3779 return (&n == this); // Always fail except on self
3780 }
3781
3782 //------------------------------Identity---------------------------------------
3783 Node* MergeMemNode::Identity(PhaseTransform *phase) {
3784 // Identity if this merge point does not record any interesting memory
3785 // disambiguations.
3786 Node* base_mem = base_memory();
3787 Node* empty_mem = empty_memory();
3788 if (base_mem != empty_mem) { // Memory path is not dead?
3789 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3790 Node* mem = in(i);
3791 if (mem != empty_mem && mem != base_mem) {
3792 return this; // Many memory splits; no change
3793 }
3794 }
3795 }
3796 return base_mem; // No memory splits; ID on the one true input
3797 }
3798
3799 //------------------------------Ideal------------------------------------------
3800 // This method is invoked recursively on chains of MergeMem nodes
3801 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3802 // Remove chain'd MergeMems
3803 //
3804 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
3805 // relative to the "in(Bot)". Since we are patching both at the same time,
3806 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
3807 // but rewrite each "in(i)" relative to the new "in(Bot)".
3808 Node *progress = NULL;
3809
3810
3811 Node* old_base = base_memory();
3812 Node* empty_mem = empty_memory();
3813 if (old_base == empty_mem)
3814 return NULL; // Dead memory path.
3815
3816 MergeMemNode* old_mbase;
3817 if (old_base != NULL && old_base->is_MergeMem())
3818 old_mbase = old_base->as_MergeMem();
3819 else
3820 old_mbase = NULL;
3821 Node* new_base = old_base;
3822
3823 // simplify stacked MergeMems in base memory
3824 if (old_mbase) new_base = old_mbase->base_memory();
3825
3826 // the base memory might contribute new slices beyond my req()
3827 if (old_mbase) grow_to_match(old_mbase);
3828
3829 // Look carefully at the base node if it is a phi.
3830 PhiNode* phi_base;
3831 if (new_base != NULL && new_base->is_Phi())
3832 phi_base = new_base->as_Phi();
3833 else
3834 phi_base = NULL;
3835
3836 Node* phi_reg = NULL;
3837 uint phi_len = (uint)-1;
3838 if (phi_base != NULL && !phi_base->is_copy()) {
3839 // do not examine phi if degraded to a copy
3840 phi_reg = phi_base->region();
3841 phi_len = phi_base->req();
3842 // see if the phi is unfinished
3843 for (uint i = 1; i < phi_len; i++) {
3844 if (phi_base->in(i) == NULL) {
3845 // incomplete phi; do not look at it yet!
3846 phi_reg = NULL;
3847 phi_len = (uint)-1;
3848 break;
3849 }
3850 }
3851 }
3852
3853 // Note: We do not call verify_sparse on entry, because inputs
3854 // can normalize to the base_memory via subsume_node or similar
3855 // mechanisms. This method repairs that damage.
3856
3857 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
3858
3859 // Look at each slice.
3860 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3861 Node* old_in = in(i);
3862 // calculate the old memory value
3863 Node* old_mem = old_in;
3864 if (old_mem == empty_mem) old_mem = old_base;
3865 assert(old_mem == memory_at(i), "");
3866
3867 // maybe update (reslice) the old memory value
3868
3869 // simplify stacked MergeMems
3870 Node* new_mem = old_mem;
3871 MergeMemNode* old_mmem;
3872 if (old_mem != NULL && old_mem->is_MergeMem())
3873 old_mmem = old_mem->as_MergeMem();
3874 else
3875 old_mmem = NULL;
3876 if (old_mmem == this) {
3877 // This can happen if loops break up and safepoints disappear.
3878 // A merge of BotPtr (default) with a RawPtr memory derived from a
3879 // safepoint can be rewritten to a merge of the same BotPtr with
3880 // the BotPtr phi coming into the loop. If that phi disappears
3881 // also, we can end up with a self-loop of the mergemem.
3882 // In general, if loops degenerate and memory effects disappear,
3883 // a mergemem can be left looking at itself. This simply means
3884 // that the mergemem's default should be used, since there is
3885 // no longer any apparent effect on this slice.
3886 // Note: If a memory slice is a MergeMem cycle, it is unreachable
3887 // from start. Update the input to TOP.
3888 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
3889 }
3890 else if (old_mmem != NULL) {
3891 new_mem = old_mmem->memory_at(i);
3892 }
3893 // else preceding memory was not a MergeMem
3894
3895 // replace equivalent phis (unfortunately, they do not GVN together)
3896 if (new_mem != NULL && new_mem != new_base &&
3897 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) {
3898 if (new_mem->is_Phi()) {
3899 PhiNode* phi_mem = new_mem->as_Phi();
3900 for (uint i = 1; i < phi_len; i++) {
3901 if (phi_base->in(i) != phi_mem->in(i)) {
3902 phi_mem = NULL;
3903 break;
3904 }
3905 }
3906 if (phi_mem != NULL) {
3907 // equivalent phi nodes; revert to the def
3908 new_mem = new_base;
3909 }
3910 }
3911 }
3912
3913 // maybe store down a new value
3914 Node* new_in = new_mem;
3915 if (new_in == new_base) new_in = empty_mem;
3916
3917 if (new_in != old_in) {
3918 // Warning: Do not combine this "if" with the previous "if"
3919 // A memory slice might have be be rewritten even if it is semantically
3920 // unchanged, if the base_memory value has changed.
3921 set_req(i, new_in);
3922 progress = this; // Report progress
3923 }
3924 }
3925
3926 if (new_base != old_base) {
3927 set_req(Compile::AliasIdxBot, new_base);
3928 // Don't use set_base_memory(new_base), because we need to update du.
3929 assert(base_memory() == new_base, "");
3930 progress = this;
3931 }
3932
3933 if( base_memory() == this ) {
3934 // a self cycle indicates this memory path is dead
3935 set_req(Compile::AliasIdxBot, empty_mem);
3936 }
3937
3938 // Resolve external cycles by calling Ideal on a MergeMem base_memory
3939 // Recursion must occur after the self cycle check above
3940 if( base_memory()->is_MergeMem() ) {
3941 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
3942 Node *m = phase->transform(new_mbase); // Rollup any cycles
3943 if( m != NULL && (m->is_top() ||
3944 m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem) ) {
3945 // propagate rollup of dead cycle to self
3946 set_req(Compile::AliasIdxBot, empty_mem);
3947 }
3948 }
3949
3950 if( base_memory() == empty_mem ) {
3951 progress = this;
3952 // Cut inputs during Parse phase only.
3953 // During Optimize phase a dead MergeMem node will be subsumed by Top.
3954 if( !can_reshape ) {
3955 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3956 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
3957 }
3958 }
3959 }
3960
3961 if( !progress && base_memory()->is_Phi() && can_reshape ) {
3962 // Check if PhiNode::Ideal's "Split phis through memory merges"
3963 // transform should be attempted. Look for this->phi->this cycle.
3964 uint merge_width = req();
3965 if (merge_width > Compile::AliasIdxRaw) {
3966 PhiNode* phi = base_memory()->as_Phi();
3967 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
3968 if (phi->in(i) == this) {
3969 phase->is_IterGVN()->_worklist.push(phi);
3970 break;
3971 }
3972 }
3973 }
3974 }
3975
3976 assert(progress || verify_sparse(), "please, no dups of base");
3977 return progress;
3978 }
3979
3980 //-------------------------set_base_memory-------------------------------------
3981 void MergeMemNode::set_base_memory(Node *new_base) {
3982 Node* empty_mem = empty_memory();
3983 set_req(Compile::AliasIdxBot, new_base);
3984 assert(memory_at(req()) == new_base, "must set default memory");
3985 // Clear out other occurrences of new_base:
3986 if (new_base != empty_mem) {
3987 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3988 if (in(i) == new_base) set_req(i, empty_mem);
3989 }
3990 }
3991 }
3992
3993 //------------------------------out_RegMask------------------------------------
3994 const RegMask &MergeMemNode::out_RegMask() const {
3995 return RegMask::Empty;
3996 }
3997
3998 //------------------------------dump_spec--------------------------------------
3999 #ifndef PRODUCT
4000 void MergeMemNode::dump_spec(outputStream *st) const {
4001 st->print(" {");
4002 Node* base_mem = base_memory();
4003 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
4004 Node* mem = memory_at(i);
4005 if (mem == base_mem) { st->print(" -"); continue; }
4006 st->print( " N%d:", mem->_idx );
4007 Compile::current()->get_adr_type(i)->dump_on(st);
4008 }
4009 st->print(" }");
4010 }
4011 #endif // !PRODUCT
4012
4013
4014 #ifdef ASSERT
4015 static bool might_be_same(Node* a, Node* b) {
4016 if (a == b) return true;
4017 if (!(a->is_Phi() || b->is_Phi())) return false;
4018 // phis shift around during optimization
4019 return true; // pretty stupid...
4020 }
4021
4022 // verify a narrow slice (either incoming or outgoing)
4023 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
4024 if (!VerifyAliases) return; // don't bother to verify unless requested
4025 if (is_error_reported()) return; // muzzle asserts when debugging an error
4026 if (Node::in_dump()) return; // muzzle asserts when printing
4027 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
4028 assert(n != NULL, "");
4029 // Elide intervening MergeMem's
4030 while (n->is_MergeMem()) {
4031 n = n->as_MergeMem()->memory_at(alias_idx);
4032 }
4033 Compile* C = Compile::current();
4034 const TypePtr* n_adr_type = n->adr_type();
4035 if (n == m->empty_memory()) {
4036 // Implicit copy of base_memory()
4037 } else if (n_adr_type != TypePtr::BOTTOM) {
4038 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type");
4039 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
4040 } else {
4041 // A few places like make_runtime_call "know" that VM calls are narrow,
4042 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
4043 bool expected_wide_mem = false;
4044 if (n == m->base_memory()) {
4045 expected_wide_mem = true;
4046 } else if (alias_idx == Compile::AliasIdxRaw ||
4047 n == m->memory_at(Compile::AliasIdxRaw)) {
4048 expected_wide_mem = true;
4049 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
4050 // memory can "leak through" calls on channels that
4051 // are write-once. Allow this also.
4052 expected_wide_mem = true;
4053 }
4054 assert(expected_wide_mem, "expected narrow slice replacement");
4055 }
4056 }
4057 #else // !ASSERT
4058 #define verify_memory_slice(m,i,n) (0) // PRODUCT version is no-op
4059 #endif
4060
4061
4062 //-----------------------------memory_at---------------------------------------
4063 Node* MergeMemNode::memory_at(uint alias_idx) const {
4064 assert(alias_idx >= Compile::AliasIdxRaw ||
4065 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0,
4066 "must avoid base_memory and AliasIdxTop");
4067
4068 // Otherwise, it is a narrow slice.
4069 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
4070 Compile *C = Compile::current();
4071 if (is_empty_memory(n)) {
4072 // the array is sparse; empty slots are the "top" node
4073 n = base_memory();
4074 assert(Node::in_dump()
4075 || n == NULL || n->bottom_type() == Type::TOP
4076 || n->adr_type() == TypePtr::BOTTOM
4077 || n->adr_type() == TypeRawPtr::BOTTOM
4078 || Compile::current()->AliasLevel() == 0,
4079 "must be a wide memory");
4080 // AliasLevel == 0 if we are organizing the memory states manually.
4081 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
4082 } else {
4083 // make sure the stored slice is sane
4084 #ifdef ASSERT
4085 if (is_error_reported() || Node::in_dump()) {
4086 } else if (might_be_same(n, base_memory())) {
4087 // Give it a pass: It is a mostly harmless repetition of the base.
4088 // This can arise normally from node subsumption during optimization.
4089 } else {
4090 verify_memory_slice(this, alias_idx, n);
4091 }
4092 #endif
4093 }
4094 return n;
4095 }
4096
4097 //---------------------------set_memory_at-------------------------------------
4098 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
4099 verify_memory_slice(this, alias_idx, n);
4100 Node* empty_mem = empty_memory();
4101 if (n == base_memory()) n = empty_mem; // collapse default
4102 uint need_req = alias_idx+1;
4103 if (req() < need_req) {
4104 if (n == empty_mem) return; // already the default, so do not grow me
4105 // grow the sparse array
4106 do {
4107 add_req(empty_mem);
4108 } while (req() < need_req);
4109 }
4110 set_req( alias_idx, n );
4111 }
4112
4113
4114
4115 //--------------------------iteration_setup------------------------------------
4116 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
4117 if (other != NULL) {
4118 grow_to_match(other);
4119 // invariant: the finite support of mm2 is within mm->req()
4120 #ifdef ASSERT
4121 for (uint i = req(); i < other->req(); i++) {
4122 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
4123 }
4124 #endif
4125 }
4126 // Replace spurious copies of base_memory by top.
4127 Node* base_mem = base_memory();
4128 if (base_mem != NULL && !base_mem->is_top()) {
4129 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
4130 if (in(i) == base_mem)
4131 set_req(i, empty_memory());
4132 }
4133 }
4134 }
4135
4136 //---------------------------grow_to_match-------------------------------------
4137 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
4138 Node* empty_mem = empty_memory();
4139 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
4140 // look for the finite support of the other memory
4141 for (uint i = other->req(); --i >= req(); ) {
4142 if (other->in(i) != empty_mem) {
4143 uint new_len = i+1;
4144 while (req() < new_len) add_req(empty_mem);
4145 break;
4146 }
4147 }
4148 }
4149
4150 //---------------------------verify_sparse-------------------------------------
4151 #ifndef PRODUCT
4152 bool MergeMemNode::verify_sparse() const {
4153 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
4154 Node* base_mem = base_memory();
4155 // The following can happen in degenerate cases, since empty==top.
4156 if (is_empty_memory(base_mem)) return true;
4157 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4158 assert(in(i) != NULL, "sane slice");
4159 if (in(i) == base_mem) return false; // should have been the sentinel value!
4160 }
4161 return true;
4162 }
4163
4164 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
4165 Node* n;
4166 n = mm->in(idx);
4167 if (mem == n) return true; // might be empty_memory()
4168 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
4169 if (mem == n) return true;
4170 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) {
4171 if (mem == n) return true;
4172 if (n == NULL) break;
4173 }
4174 return false;
4175 }
4176 #endif // !PRODUCT