1 /*
2 * Copyright (c) 1997, 2016, 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 TypeOopPtr *t_oop, Node *load, PhaseGVN *phase) {
107 assert((t_oop != NULL), "sanity");
108 bool is_instance = t_oop->is_known_instance_field();
109 bool is_boxed_value_load = t_oop->is_ptr_to_boxed_value() &&
110 (load != NULL) && load->is_Load() &&
111 (phase->is_IterGVN() != NULL);
112 if (!(is_instance || is_boxed_value_load))
113 return mchain; // don't try to optimize non-instance types
114 uint instance_id = t_oop->instance_id();
115 Node *start_mem = phase->C->start()->proj_out(TypeFunc::Memory);
116 Node *prev = NULL;
117 Node *result = mchain;
118 while (prev != result) {
119 prev = result;
120 if (result == start_mem)
121 break; // hit one of our sentinels
122 // skip over a call which does not affect this memory slice
123 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {
124 Node *proj_in = result->in(0);
125 if (proj_in->is_Allocate() && proj_in->_idx == instance_id) {
126 break; // hit one of our sentinels
127 } else if (proj_in->is_Call()) {
128 CallNode *call = proj_in->as_Call();
129 if (!call->may_modify(t_oop, phase)) { // returns false for instances
130 result = call->in(TypeFunc::Memory);
131 }
132 } else if (proj_in->is_Initialize()) {
133 AllocateNode* alloc = proj_in->as_Initialize()->allocation();
134 // Stop if this is the initialization for the object instance which
135 // which contains this memory slice, otherwise skip over it.
136 if ((alloc == NULL) || (alloc->_idx == instance_id)) {
137 break;
138 }
139 if (is_instance) {
140 result = proj_in->in(TypeFunc::Memory);
141 } else if (is_boxed_value_load) {
142 Node* klass = alloc->in(AllocateNode::KlassNode);
143 const TypeKlassPtr* tklass = phase->type(klass)->is_klassptr();
144 if (tklass->klass_is_exact() && !tklass->klass()->equals(t_oop->klass())) {
145 result = proj_in->in(TypeFunc::Memory); // not related allocation
146 }
147 }
148 } else if (proj_in->is_MemBar()) {
149 result = proj_in->in(TypeFunc::Memory);
150 } else {
151 assert(false, "unexpected projection");
152 }
153 } else if (result->is_ClearArray()) {
154 if (!is_instance || !ClearArrayNode::step_through(&result, instance_id, phase)) {
155 // Can not bypass initialization of the instance
156 // we are looking for.
157 break;
158 }
159 // Otherwise skip it (the call updated 'result' value).
160 } else if (result->is_MergeMem()) {
161 result = step_through_mergemem(phase, result->as_MergeMem(), t_oop, NULL, tty);
162 }
163 }
164 return result;
165 }
166
167 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, Node *load, PhaseGVN *phase) {
168 const TypeOopPtr* t_oop = t_adr->isa_oopptr();
169 if (t_oop == NULL)
170 return mchain; // don't try to optimize non-oop types
171 Node* result = optimize_simple_memory_chain(mchain, t_oop, load, phase);
172 bool is_instance = t_oop->is_known_instance_field();
173 PhaseIterGVN *igvn = phase->is_IterGVN();
174 if (is_instance && igvn != NULL && result->is_Phi()) {
175 PhiNode *mphi = result->as_Phi();
176 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
177 const TypePtr *t = mphi->adr_type();
178 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
179 t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
180 t->is_oopptr()->cast_to_exactness(true)
181 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
182 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop) {
183 // clone the Phi with our address type
184 result = mphi->split_out_instance(t_adr, igvn);
185 } else {
186 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain");
187 }
188 }
189 return result;
190 }
191
192 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) {
193 uint alias_idx = phase->C->get_alias_index(tp);
194 Node *mem = mmem;
195 #ifdef ASSERT
196 {
197 // Check that current type is consistent with the alias index used during graph construction
198 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
199 bool consistent = adr_check == NULL || adr_check->empty() ||
200 phase->C->must_alias(adr_check, alias_idx );
201 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
202 if( !consistent && adr_check != NULL && !adr_check->empty() &&
203 tp->isa_aryptr() && tp->offset() == Type::OffsetBot &&
204 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot &&
205 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() ||
206 adr_check->offset() == oopDesc::klass_offset_in_bytes() ||
207 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) {
208 // don't assert if it is dead code.
209 consistent = true;
210 }
211 if( !consistent ) {
212 st->print("alias_idx==%d, adr_check==", alias_idx);
213 if( adr_check == NULL ) {
214 st->print("NULL");
215 } else {
216 adr_check->dump();
217 }
218 st->cr();
219 print_alias_types();
220 assert(consistent, "adr_check must match alias idx");
221 }
222 }
223 #endif
224 // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally
225 // means an array I have not precisely typed yet. Do not do any
226 // alias stuff with it any time soon.
227 const TypeOopPtr *toop = tp->isa_oopptr();
228 if( tp->base() != Type::AnyPtr &&
229 !(toop &&
230 toop->klass() != NULL &&
231 toop->klass()->is_java_lang_Object() &&
232 toop->offset() == Type::OffsetBot) ) {
233 // compress paths and change unreachable cycles to TOP
234 // If not, we can update the input infinitely along a MergeMem cycle
235 // Equivalent code in PhiNode::Ideal
236 Node* m = phase->transform(mmem);
237 // If transformed to a MergeMem, get the desired slice
238 // Otherwise the returned node represents memory for every slice
239 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
240 // Update input if it is progress over what we have now
241 }
242 return mem;
243 }
244
245 //--------------------------Ideal_common---------------------------------------
246 // Look for degenerate control and memory inputs. Bypass MergeMem inputs.
247 // Unhook non-raw memories from complete (macro-expanded) initializations.
248 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
249 // If our control input is a dead region, kill all below the region
250 Node *ctl = in(MemNode::Control);
251 if (ctl && remove_dead_region(phase, can_reshape))
252 return this;
253 ctl = in(MemNode::Control);
254 // Don't bother trying to transform a dead node
255 if (ctl && ctl->is_top()) return NodeSentinel;
256
257 PhaseIterGVN *igvn = phase->is_IterGVN();
258 // Wait if control on the worklist.
259 if (ctl && can_reshape && igvn != NULL) {
260 Node* bol = NULL;
261 Node* cmp = NULL;
262 if (ctl->in(0)->is_If()) {
263 assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity");
264 bol = ctl->in(0)->in(1);
265 if (bol->is_Bool())
266 cmp = ctl->in(0)->in(1)->in(1);
267 }
268 if (igvn->_worklist.member(ctl) ||
269 (bol != NULL && igvn->_worklist.member(bol)) ||
270 (cmp != NULL && igvn->_worklist.member(cmp)) ) {
271 // This control path may be dead.
272 // Delay this memory node transformation until the control is processed.
273 phase->is_IterGVN()->_worklist.push(this);
274 return NodeSentinel; // caller will return NULL
275 }
276 }
277 // Ignore if memory is dead, or self-loop
278 Node *mem = in(MemNode::Memory);
279 if (phase->type( mem ) == Type::TOP) return NodeSentinel; // caller will return NULL
280 assert(mem != this, "dead loop in MemNode::Ideal");
281
282 if (can_reshape && igvn != NULL && igvn->_worklist.member(mem)) {
283 // This memory slice may be dead.
284 // Delay this mem node transformation until the memory is processed.
285 phase->is_IterGVN()->_worklist.push(this);
286 return NodeSentinel; // caller will return NULL
287 }
288
289 Node *address = in(MemNode::Address);
290 const Type *t_adr = phase->type(address);
291 if (t_adr == Type::TOP) return NodeSentinel; // caller will return NULL
292
293 if (can_reshape && igvn != NULL &&
294 (igvn->_worklist.member(address) ||
295 igvn->_worklist.size() > 0 && (t_adr != adr_type())) ) {
296 // The address's base and type may change when the address is processed.
297 // Delay this mem node transformation until the address is processed.
298 phase->is_IterGVN()->_worklist.push(this);
299 return NodeSentinel; // caller will return NULL
300 }
301
302 // Do NOT remove or optimize the next lines: ensure a new alias index
303 // is allocated for an oop pointer type before Escape Analysis.
304 // Note: C++ will not remove it since the call has side effect.
305 if (t_adr->isa_oopptr()) {
306 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr());
307 }
308
309 Node* base = NULL;
310 if (address->is_AddP()) {
311 base = address->in(AddPNode::Base);
312 }
313 if (base != NULL && phase->type(base)->higher_equal(TypePtr::NULL_PTR) &&
314 !t_adr->isa_rawptr()) {
315 // Note: raw address has TOP base and top->higher_equal(TypePtr::NULL_PTR) is true.
316 // Skip this node optimization if its address has TOP base.
317 return NodeSentinel; // caller will return NULL
318 }
319
320 // Avoid independent memory operations
321 Node* old_mem = mem;
322
323 // The code which unhooks non-raw memories from complete (macro-expanded)
324 // initializations was removed. After macro-expansion all stores catched
325 // by Initialize node became raw stores and there is no information
326 // which memory slices they modify. So it is unsafe to move any memory
327 // operation above these stores. Also in most cases hooked non-raw memories
328 // were already unhooked by using information from detect_ptr_independence()
329 // and find_previous_store().
330
331 if (mem->is_MergeMem()) {
332 MergeMemNode* mmem = mem->as_MergeMem();
333 const TypePtr *tp = t_adr->is_ptr();
334
335 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
336 }
337
338 if (mem != old_mem) {
339 set_req(MemNode::Memory, mem);
340 if (can_reshape && old_mem->outcnt() == 0) {
341 igvn->_worklist.push(old_mem);
342 }
343 if (phase->type( mem ) == Type::TOP) return NodeSentinel;
344 return this;
345 }
346
347 // let the subclass continue analyzing...
348 return NULL;
349 }
350
351 // Helper function for proving some simple control dominations.
352 // Attempt to prove that all control inputs of 'dom' dominate 'sub'.
353 // Already assumes that 'dom' is available at 'sub', and that 'sub'
354 // is not a constant (dominated by the method's StartNode).
355 // Used by MemNode::find_previous_store to prove that the
356 // control input of a memory operation predates (dominates)
357 // an allocation it wants to look past.
358 bool MemNode::all_controls_dominate(Node* dom, Node* sub) {
359 if (dom == NULL || dom->is_top() || sub == NULL || sub->is_top())
360 return false; // Conservative answer for dead code
361
362 // Check 'dom'. Skip Proj and CatchProj nodes.
363 dom = dom->find_exact_control(dom);
364 if (dom == NULL || dom->is_top())
365 return false; // Conservative answer for dead code
366
367 if (dom == sub) {
368 // For the case when, for example, 'sub' is Initialize and the original
369 // 'dom' is Proj node of the 'sub'.
370 return false;
371 }
372
373 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub)
374 return true;
375
376 // 'dom' dominates 'sub' if its control edge and control edges
377 // of all its inputs dominate or equal to sub's control edge.
378
379 // Currently 'sub' is either Allocate, Initialize or Start nodes.
380 // Or Region for the check in LoadNode::Ideal();
381 // 'sub' should have sub->in(0) != NULL.
382 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() ||
383 sub->is_Region() || sub->is_Call(), "expecting only these nodes");
384
385 // Get control edge of 'sub'.
386 Node* orig_sub = sub;
387 sub = sub->find_exact_control(sub->in(0));
388 if (sub == NULL || sub->is_top())
389 return false; // Conservative answer for dead code
390
391 assert(sub->is_CFG(), "expecting control");
392
393 if (sub == dom)
394 return true;
395
396 if (sub->is_Start() || sub->is_Root())
397 return false;
398
399 {
400 // Check all control edges of 'dom'.
401
402 ResourceMark rm;
403 Arena* arena = Thread::current()->resource_area();
404 Node_List nlist(arena);
405 Unique_Node_List dom_list(arena);
406
407 dom_list.push(dom);
408 bool only_dominating_controls = false;
409
410 for (uint next = 0; next < dom_list.size(); next++) {
411 Node* n = dom_list.at(next);
412 if (n == orig_sub)
413 return false; // One of dom's inputs dominated by sub.
414 if (!n->is_CFG() && n->pinned()) {
415 // Check only own control edge for pinned non-control nodes.
416 n = n->find_exact_control(n->in(0));
417 if (n == NULL || n->is_top())
418 return false; // Conservative answer for dead code
419 assert(n->is_CFG(), "expecting control");
420 dom_list.push(n);
421 } else if (n->is_Con() || n->is_Start() || n->is_Root()) {
422 only_dominating_controls = true;
423 } else if (n->is_CFG()) {
424 if (n->dominates(sub, nlist))
425 only_dominating_controls = true;
426 else
427 return false;
428 } else {
429 // First, own control edge.
430 Node* m = n->find_exact_control(n->in(0));
431 if (m != NULL) {
432 if (m->is_top())
433 return false; // Conservative answer for dead code
434 dom_list.push(m);
435 }
436 // Now, the rest of edges.
437 uint cnt = n->req();
438 for (uint i = 1; i < cnt; i++) {
439 m = n->find_exact_control(n->in(i));
440 if (m == NULL || m->is_top())
441 continue;
442 dom_list.push(m);
443 }
444 }
445 }
446 return only_dominating_controls;
447 }
448 }
449
450 //---------------------detect_ptr_independence---------------------------------
451 // Used by MemNode::find_previous_store to prove that two base
452 // pointers are never equal.
453 // The pointers are accompanied by their associated allocations,
454 // if any, which have been previously discovered by the caller.
455 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
456 Node* p2, AllocateNode* a2,
457 PhaseTransform* phase) {
458 // Attempt to prove that these two pointers cannot be aliased.
459 // They may both manifestly be allocations, and they should differ.
460 // Or, if they are not both allocations, they can be distinct constants.
461 // Otherwise, one is an allocation and the other a pre-existing value.
462 if (a1 == NULL && a2 == NULL) { // neither an allocation
463 return (p1 != p2) && p1->is_Con() && p2->is_Con();
464 } else if (a1 != NULL && a2 != NULL) { // both allocations
465 return (a1 != a2);
466 } else if (a1 != NULL) { // one allocation a1
467 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.)
468 return all_controls_dominate(p2, a1);
469 } else { //(a2 != NULL) // one allocation a2
470 return all_controls_dominate(p1, a2);
471 }
472 return false;
473 }
474
475
476 // The logic for reordering loads and stores uses four steps:
477 // (a) Walk carefully past stores and initializations which we
478 // can prove are independent of this load.
479 // (b) Observe that the next memory state makes an exact match
480 // with self (load or store), and locate the relevant store.
481 // (c) Ensure that, if we were to wire self directly to the store,
482 // the optimizer would fold it up somehow.
483 // (d) Do the rewiring, and return, depending on some other part of
484 // the optimizer to fold up the load.
485 // This routine handles steps (a) and (b). Steps (c) and (d) are
486 // specific to loads and stores, so they are handled by the callers.
487 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.)
488 //
489 Node* MemNode::find_previous_store(PhaseTransform* phase) {
490 Node* ctrl = in(MemNode::Control);
491 Node* adr = in(MemNode::Address);
492 intptr_t offset = 0;
493 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
494 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase);
495
496 if (offset == Type::OffsetBot)
497 return NULL; // cannot unalias unless there are precise offsets
498
499 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr();
500
501 intptr_t size_in_bytes = memory_size();
502
503 Node* mem = in(MemNode::Memory); // start searching here...
504
505 int cnt = 50; // Cycle limiter
506 for (;;) { // While we can dance past unrelated stores...
507 if (--cnt < 0) break; // Caught in cycle or a complicated dance?
508
509 if (mem->is_Store()) {
510 Node* st_adr = mem->in(MemNode::Address);
511 intptr_t st_offset = 0;
512 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
513 if (st_base == NULL)
514 break; // inscrutable pointer
515 if (st_offset != offset && st_offset != Type::OffsetBot) {
516 const int MAX_STORE = BytesPerLong;
517 if (st_offset >= offset + size_in_bytes ||
518 st_offset <= offset - MAX_STORE ||
519 st_offset <= offset - mem->as_Store()->memory_size()) {
520 // Success: The offsets are provably independent.
521 // (You may ask, why not just test st_offset != offset and be done?
522 // The answer is that stores of different sizes can co-exist
523 // in the same sequence of RawMem effects. We sometimes initialize
524 // a whole 'tile' of array elements with a single jint or jlong.)
525 mem = mem->in(MemNode::Memory);
526 continue; // (a) advance through independent store memory
527 }
528 }
529 if (st_base != base &&
530 detect_ptr_independence(base, alloc,
531 st_base,
532 AllocateNode::Ideal_allocation(st_base, phase),
533 phase)) {
534 // Success: The bases are provably independent.
535 mem = mem->in(MemNode::Memory);
536 continue; // (a) advance through independent store memory
537 }
538
539 // (b) At this point, if the bases or offsets do not agree, we lose,
540 // since we have not managed to prove 'this' and 'mem' independent.
541 if (st_base == base && st_offset == offset) {
542 return mem; // let caller handle steps (c), (d)
543 }
544
545 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
546 InitializeNode* st_init = mem->in(0)->as_Initialize();
547 AllocateNode* st_alloc = st_init->allocation();
548 if (st_alloc == NULL)
549 break; // something degenerated
550 bool known_identical = false;
551 bool known_independent = false;
552 if (alloc == st_alloc)
553 known_identical = true;
554 else if (alloc != NULL)
555 known_independent = true;
556 else if (all_controls_dominate(this, st_alloc))
557 known_independent = true;
558
559 if (known_independent) {
560 // The bases are provably independent: Either they are
561 // manifestly distinct allocations, or else the control
562 // of this load dominates the store's allocation.
563 int alias_idx = phase->C->get_alias_index(adr_type());
564 if (alias_idx == Compile::AliasIdxRaw) {
565 mem = st_alloc->in(TypeFunc::Memory);
566 } else {
567 mem = st_init->memory(alias_idx);
568 }
569 continue; // (a) advance through independent store memory
570 }
571
572 // (b) at this point, if we are not looking at a store initializing
573 // the same allocation we are loading from, we lose.
574 if (known_identical) {
575 // From caller, can_see_stored_value will consult find_captured_store.
576 return mem; // let caller handle steps (c), (d)
577 }
578
579 } else if (addr_t != NULL && addr_t->is_known_instance_field()) {
580 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
581 if (mem->is_Proj() && mem->in(0)->is_Call()) {
582 CallNode *call = mem->in(0)->as_Call();
583 if (!call->may_modify(addr_t, phase)) {
584 mem = call->in(TypeFunc::Memory);
585 continue; // (a) advance through independent call memory
586 }
587 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) {
588 mem = mem->in(0)->in(TypeFunc::Memory);
589 continue; // (a) advance through independent MemBar memory
590 } else if (mem->is_ClearArray()) {
591 if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) {
592 // (the call updated 'mem' value)
593 continue; // (a) advance through independent allocation memory
594 } else {
595 // Can not bypass initialization of the instance
596 // we are looking for.
597 return mem;
598 }
599 } else if (mem->is_MergeMem()) {
600 int alias_idx = phase->C->get_alias_index(adr_type());
601 mem = mem->as_MergeMem()->memory_at(alias_idx);
602 continue; // (a) advance through independent MergeMem memory
603 }
604 }
605
606 // Unless there is an explicit 'continue', we must bail out here,
607 // because 'mem' is an inscrutable memory state (e.g., a call).
608 break;
609 }
610
611 return NULL; // bail out
612 }
613
614 //----------------------calculate_adr_type-------------------------------------
615 // Helper function. Notices when the given type of address hits top or bottom.
616 // Also, asserts a cross-check of the type against the expected address type.
617 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
618 if (t == Type::TOP) return NULL; // does not touch memory any more?
619 #ifdef PRODUCT
620 cross_check = NULL;
621 #else
622 if (!VerifyAliases || is_error_reported() || Node::in_dump()) cross_check = NULL;
623 #endif
624 const TypePtr* tp = t->isa_ptr();
625 if (tp == NULL) {
626 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
627 return TypePtr::BOTTOM; // touches lots of memory
628 } else {
629 #ifdef ASSERT
630 // %%%% [phh] We don't check the alias index if cross_check is
631 // TypeRawPtr::BOTTOM. Needs to be investigated.
632 if (cross_check != NULL &&
633 cross_check != TypePtr::BOTTOM &&
634 cross_check != TypeRawPtr::BOTTOM) {
635 // Recheck the alias index, to see if it has changed (due to a bug).
636 Compile* C = Compile::current();
637 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
638 "must stay in the original alias category");
639 // The type of the address must be contained in the adr_type,
640 // disregarding "null"-ness.
641 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
642 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
643 assert(cross_check->meet(tp_notnull) == cross_check->remove_speculative(),
644 "real address must not escape from expected memory type");
645 }
646 #endif
647 return tp;
648 }
649 }
650
651 //------------------------adr_phi_is_loop_invariant----------------------------
652 // A helper function for Ideal_DU_postCCP to check if a Phi in a counted
653 // loop is loop invariant. Make a quick traversal of Phi and associated
654 // CastPP nodes, looking to see if they are a closed group within the loop.
655 bool MemNode::adr_phi_is_loop_invariant(Node* adr_phi, Node* cast) {
656 // The idea is that the phi-nest must boil down to only CastPP nodes
657 // with the same data. This implies that any path into the loop already
658 // includes such a CastPP, and so the original cast, whatever its input,
659 // must be covered by an equivalent cast, with an earlier control input.
660 ResourceMark rm;
661
662 // The loop entry input of the phi should be the unique dominating
663 // node for every Phi/CastPP in the loop.
664 Unique_Node_List closure;
665 closure.push(adr_phi->in(LoopNode::EntryControl));
666
667 // Add the phi node and the cast to the worklist.
668 Unique_Node_List worklist;
669 worklist.push(adr_phi);
670 if( cast != NULL ){
671 if( !cast->is_ConstraintCast() ) return false;
672 worklist.push(cast);
673 }
674
675 // Begin recursive walk of phi nodes.
676 while( worklist.size() ){
677 // Take a node off the worklist
678 Node *n = worklist.pop();
679 if( !closure.member(n) ){
680 // Add it to the closure.
681 closure.push(n);
682 // Make a sanity check to ensure we don't waste too much time here.
683 if( closure.size() > 20) return false;
684 // This node is OK if:
685 // - it is a cast of an identical value
686 // - or it is a phi node (then we add its inputs to the worklist)
687 // Otherwise, the node is not OK, and we presume the cast is not invariant
688 if( n->is_ConstraintCast() ){
689 worklist.push(n->in(1));
690 } else if( n->is_Phi() ) {
691 for( uint i = 1; i < n->req(); i++ ) {
692 worklist.push(n->in(i));
693 }
694 } else {
695 return false;
696 }
697 }
698 }
699
700 // Quit when the worklist is empty, and we've found no offending nodes.
701 return true;
702 }
703
704 //------------------------------Ideal_DU_postCCP-------------------------------
705 // Find any cast-away of null-ness and keep its control. Null cast-aways are
706 // going away in this pass and we need to make this memory op depend on the
707 // gating null check.
708 Node *MemNode::Ideal_DU_postCCP( PhaseCCP *ccp ) {
709 return Ideal_common_DU_postCCP(ccp, this, in(MemNode::Address));
710 }
711
712 // I tried to leave the CastPP's in. This makes the graph more accurate in
713 // some sense; we get to keep around the knowledge that an oop is not-null
714 // after some test. Alas, the CastPP's interfere with GVN (some values are
715 // the regular oop, some are the CastPP of the oop, all merge at Phi's which
716 // cannot collapse, etc). This cost us 10% on SpecJVM, even when I removed
717 // some of the more trivial cases in the optimizer. Removing more useless
718 // Phi's started allowing Loads to illegally float above null checks. I gave
719 // up on this approach. CNC 10/20/2000
720 // This static method may be called not from MemNode (EncodePNode calls it).
721 // Only the control edge of the node 'n' might be updated.
722 Node *MemNode::Ideal_common_DU_postCCP( PhaseCCP *ccp, Node* n, Node* adr ) {
723 Node *skipped_cast = NULL;
724 // Need a null check? Regular static accesses do not because they are
725 // from constant addresses. Array ops are gated by the range check (which
726 // always includes a NULL check). Just check field ops.
727 if( n->in(MemNode::Control) == NULL ) {
728 // Scan upwards for the highest location we can place this memory op.
729 while( true ) {
730 switch( adr->Opcode() ) {
731
732 case Op_AddP: // No change to NULL-ness, so peek thru AddP's
733 adr = adr->in(AddPNode::Base);
734 continue;
735
736 case Op_DecodeN: // No change to NULL-ness, so peek thru
737 case Op_DecodeNKlass:
738 adr = adr->in(1);
739 continue;
740
741 case Op_EncodeP:
742 case Op_EncodePKlass:
743 // EncodeP node's control edge could be set by this method
744 // when EncodeP node depends on CastPP node.
745 //
746 // Use its control edge for memory op because EncodeP may go away
747 // later when it is folded with following or preceding DecodeN node.
748 if (adr->in(0) == NULL) {
749 // Keep looking for cast nodes.
750 adr = adr->in(1);
751 continue;
752 }
753 ccp->hash_delete(n);
754 n->set_req(MemNode::Control, adr->in(0));
755 ccp->hash_insert(n);
756 return n;
757
758 case Op_CastPP:
759 // If the CastPP is useless, just peek on through it.
760 if( ccp->type(adr) == ccp->type(adr->in(1)) ) {
761 // Remember the cast that we've peeked though. If we peek
762 // through more than one, then we end up remembering the highest
763 // one, that is, if in a loop, the one closest to the top.
764 skipped_cast = adr;
765 adr = adr->in(1);
766 continue;
767 }
768 // CastPP is going away in this pass! We need this memory op to be
769 // control-dependent on the test that is guarding the CastPP.
770 ccp->hash_delete(n);
771 n->set_req(MemNode::Control, adr->in(0));
772 ccp->hash_insert(n);
773 return n;
774
775 case Op_Phi:
776 // Attempt to float above a Phi to some dominating point.
777 if (adr->in(0) != NULL && adr->in(0)->is_CountedLoop()) {
778 // If we've already peeked through a Cast (which could have set the
779 // control), we can't float above a Phi, because the skipped Cast
780 // may not be loop invariant.
781 if (adr_phi_is_loop_invariant(adr, skipped_cast)) {
782 adr = adr->in(1);
783 continue;
784 }
785 }
786
787 // Intentional fallthrough!
788
789 // No obvious dominating point. The mem op is pinned below the Phi
790 // by the Phi itself. If the Phi goes away (no true value is merged)
791 // then the mem op can float, but not indefinitely. It must be pinned
792 // behind the controls leading to the Phi.
793 case Op_CheckCastPP:
794 // These usually stick around to change address type, however a
795 // useless one can be elided and we still need to pick up a control edge
796 if (adr->in(0) == NULL) {
797 // This CheckCastPP node has NO control and is likely useless. But we
798 // need check further up the ancestor chain for a control input to keep
799 // the node in place. 4959717.
800 skipped_cast = adr;
801 adr = adr->in(1);
802 continue;
803 }
804 ccp->hash_delete(n);
805 n->set_req(MemNode::Control, adr->in(0));
806 ccp->hash_insert(n);
807 return n;
808
809 // List of "safe" opcodes; those that implicitly block the memory
810 // op below any null check.
811 case Op_CastX2P: // no null checks on native pointers
812 case Op_Parm: // 'this' pointer is not null
813 case Op_LoadP: // Loading from within a klass
814 case Op_LoadN: // Loading from within a klass
815 case Op_LoadKlass: // Loading from within a klass
816 case Op_LoadNKlass: // Loading from within a klass
817 case Op_ConP: // Loading from a klass
818 case Op_ConN: // Loading from a klass
819 case Op_ConNKlass: // Loading from a klass
820 case Op_CreateEx: // Sucking up the guts of an exception oop
821 case Op_Con: // Reading from TLS
822 case Op_CMoveP: // CMoveP is pinned
823 case Op_CMoveN: // CMoveN is pinned
824 break; // No progress
825
826 case Op_Proj: // Direct call to an allocation routine
827 case Op_SCMemProj: // Memory state from store conditional ops
828 #ifdef ASSERT
829 {
830 assert(adr->as_Proj()->_con == TypeFunc::Parms, "must be return value");
831 const Node* call = adr->in(0);
832 if (call->is_CallJava()) {
833 const CallJavaNode* call_java = call->as_CallJava();
834 const TypeTuple *r = call_java->tf()->range();
835 assert(r->cnt() > TypeFunc::Parms, "must return value");
836 const Type* ret_type = r->field_at(TypeFunc::Parms);
837 assert(ret_type && ret_type->isa_ptr(), "must return pointer");
838 // We further presume that this is one of
839 // new_instance_Java, new_array_Java, or
840 // the like, but do not assert for this.
841 } else if (call->is_Allocate()) {
842 // similar case to new_instance_Java, etc.
843 } else if (!call->is_CallLeaf()) {
844 // Projections from fetch_oop (OSR) are allowed as well.
845 ShouldNotReachHere();
846 }
847 }
848 #endif
849 break;
850 default:
851 ShouldNotReachHere();
852 }
853 break;
854 }
855 }
856
857 return NULL; // No progress
858 }
859
860
861 //=============================================================================
862 // Should LoadNode::Ideal() attempt to remove control edges?
863 bool LoadNode::can_remove_control() const {
864 return true;
865 }
866 uint LoadNode::size_of() const { return sizeof(*this); }
867 uint LoadNode::cmp( const Node &n ) const
868 { return !Type::cmp( _type, ((LoadNode&)n)._type ); }
869 const Type *LoadNode::bottom_type() const { return _type; }
870 uint LoadNode::ideal_reg() const {
871 return _type->ideal_reg();
872 }
873
874 #ifndef PRODUCT
875 void LoadNode::dump_spec(outputStream *st) const {
876 MemNode::dump_spec(st);
877 if( !Verbose && !WizardMode ) {
878 // standard dump does this in Verbose and WizardMode
879 st->print(" #"); _type->dump_on(st);
880 }
881 if (!_depends_only_on_test) {
882 st->print(" (does not depend only on test)");
883 }
884 }
885 #endif
886
887 #ifdef ASSERT
888 //----------------------------is_immutable_value-------------------------------
889 // Helper function to allow a raw load without control edge for some cases
890 bool LoadNode::is_immutable_value(Node* adr) {
891 return (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() &&
892 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal &&
893 (adr->in(AddPNode::Offset)->find_intptr_t_con(-1) ==
894 in_bytes(JavaThread::osthread_offset())));
895 }
896 #endif
897
898 //----------------------------LoadNode::make-----------------------------------
899 // Polymorphic factory method:
900 Node *LoadNode::make(PhaseGVN& gvn, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt, MemOrd mo, ControlDependency control_dependency) {
901 Compile* C = gvn.C;
902
903 // sanity check the alias category against the created node type
904 assert(!(adr_type->isa_oopptr() &&
905 adr_type->offset() == oopDesc::klass_offset_in_bytes()),
906 "use LoadKlassNode instead");
907 assert(!(adr_type->isa_aryptr() &&
908 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
909 "use LoadRangeNode instead");
910 // Check control edge of raw loads
911 assert( ctl != NULL || C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
912 // oop will be recorded in oop map if load crosses safepoint
913 rt->isa_oopptr() || is_immutable_value(adr),
914 "raw memory operations should have control edge");
915 switch (bt) {
916 case T_BOOLEAN: return new (C) LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency);
917 case T_BYTE: return new (C) LoadBNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency);
918 case T_INT: return new (C) LoadINode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency);
919 case T_CHAR: return new (C) LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency);
920 case T_SHORT: return new (C) LoadSNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency);
921 case T_LONG: return new (C) LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency);
922 case T_FLOAT: return new (C) LoadFNode (ctl, mem, adr, adr_type, rt, mo, control_dependency);
923 case T_DOUBLE: return new (C) LoadDNode (ctl, mem, adr, adr_type, rt, mo, control_dependency);
924 case T_ADDRESS: return new (C) LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency);
925 case T_OBJECT:
926 #ifdef _LP64
927 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
928 Node* load = gvn.transform(new (C) LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo, control_dependency));
929 return new (C) DecodeNNode(load, load->bottom_type()->make_ptr());
930 } else
931 #endif
932 {
933 assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop");
934 return new (C) LoadPNode(ctl, mem, adr, adr_type, rt->is_oopptr(), mo, control_dependency);
935 }
936 }
937 ShouldNotReachHere();
938 return (LoadNode*)NULL;
939 }
940
941 LoadLNode* LoadLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo, ControlDependency control_dependency) {
942 bool require_atomic = true;
943 return new (C) LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency, require_atomic);
944 }
945
946 LoadDNode* LoadDNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo, ControlDependency control_dependency) {
947 bool require_atomic = true;
948 return new (C) LoadDNode(ctl, mem, adr, adr_type, rt, mo, control_dependency, require_atomic);
949 }
950
951
952
953 //------------------------------hash-------------------------------------------
954 uint LoadNode::hash() const {
955 // unroll addition of interesting fields
956 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
957 }
958
959 static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) {
960 if ((atp != NULL) && (atp->index() >= Compile::AliasIdxRaw)) {
961 bool non_volatile = (atp->field() != NULL) && !atp->field()->is_volatile();
962 bool is_stable_ary = FoldStableValues &&
963 (tp != NULL) && (tp->isa_aryptr() != NULL) &&
964 tp->isa_aryptr()->is_stable();
965
966 return (eliminate_boxing && non_volatile) || is_stable_ary;
967 }
968
969 return false;
970 }
971
972 //---------------------------can_see_stored_value------------------------------
973 // This routine exists to make sure this set of tests is done the same
974 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
975 // will change the graph shape in a way which makes memory alive twice at the
976 // same time (uses the Oracle model of aliasing), then some
977 // LoadXNode::Identity will fold things back to the equivalence-class model
978 // of aliasing.
979 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const {
980 Node* ld_adr = in(MemNode::Address);
981 intptr_t ld_off = 0;
982 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
983 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
984 Compile::AliasType* atp = (tp != NULL) ? phase->C->alias_type(tp) : NULL;
985 // This is more general than load from boxing objects.
986 if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) {
987 uint alias_idx = atp->index();
988 bool final = !atp->is_rewritable();
989 Node* result = NULL;
990 Node* current = st;
991 // Skip through chains of MemBarNodes checking the MergeMems for
992 // new states for the slice of this load. Stop once any other
993 // kind of node is encountered. Loads from final memory can skip
994 // through any kind of MemBar but normal loads shouldn't skip
995 // through MemBarAcquire since the could allow them to move out of
996 // a synchronized region.
997 while (current->is_Proj()) {
998 int opc = current->in(0)->Opcode();
999 if ((final && (opc == Op_MemBarAcquire ||
1000 opc == Op_MemBarAcquireLock ||
1001 opc == Op_LoadFence)) ||
1002 opc == Op_MemBarRelease ||
1003 opc == Op_StoreFence ||
1004 opc == Op_MemBarReleaseLock ||
1005 opc == Op_MemBarCPUOrder) {
1006 Node* mem = current->in(0)->in(TypeFunc::Memory);
1007 if (mem->is_MergeMem()) {
1008 MergeMemNode* merge = mem->as_MergeMem();
1009 Node* new_st = merge->memory_at(alias_idx);
1010 if (new_st == merge->base_memory()) {
1011 // Keep searching
1012 current = new_st;
1013 continue;
1014 }
1015 // Save the new memory state for the slice and fall through
1016 // to exit.
1017 result = new_st;
1018 }
1019 }
1020 break;
1021 }
1022 if (result != NULL) {
1023 st = result;
1024 }
1025 }
1026
1027 // Loop around twice in the case Load -> Initialize -> Store.
1028 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
1029 for (int trip = 0; trip <= 1; trip++) {
1030
1031 if (st->is_Store()) {
1032 Node* st_adr = st->in(MemNode::Address);
1033 if (!phase->eqv(st_adr, ld_adr)) {
1034 // Try harder before giving up... Match raw and non-raw pointers.
1035 intptr_t st_off = 0;
1036 AllocateNode* alloc = AllocateNode::Ideal_allocation(st_adr, phase, st_off);
1037 if (alloc == NULL) return NULL;
1038 if (alloc != ld_alloc) return NULL;
1039 if (ld_off != st_off) return NULL;
1040 // At this point we have proven something like this setup:
1041 // A = Allocate(...)
1042 // L = LoadQ(, AddP(CastPP(, A.Parm),, #Off))
1043 // S = StoreQ(, AddP(, A.Parm , #Off), V)
1044 // (Actually, we haven't yet proven the Q's are the same.)
1045 // In other words, we are loading from a casted version of
1046 // the same pointer-and-offset that we stored to.
1047 // Thus, we are able to replace L by V.
1048 }
1049 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
1050 if (store_Opcode() != st->Opcode())
1051 return NULL;
1052 return st->in(MemNode::ValueIn);
1053 }
1054
1055 // A load from a freshly-created object always returns zero.
1056 // (This can happen after LoadNode::Ideal resets the load's memory input
1057 // to find_captured_store, which returned InitializeNode::zero_memory.)
1058 if (st->is_Proj() && st->in(0)->is_Allocate() &&
1059 (st->in(0) == ld_alloc) &&
1060 (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) {
1061 // return a zero value for the load's basic type
1062 // (This is one of the few places where a generic PhaseTransform
1063 // can create new nodes. Think of it as lazily manifesting
1064 // virtually pre-existing constants.)
1065 return phase->zerocon(memory_type());
1066 }
1067
1068 // A load from an initialization barrier can match a captured store.
1069 if (st->is_Proj() && st->in(0)->is_Initialize()) {
1070 InitializeNode* init = st->in(0)->as_Initialize();
1071 AllocateNode* alloc = init->allocation();
1072 if ((alloc != NULL) && (alloc == ld_alloc)) {
1073 // examine a captured store value
1074 st = init->find_captured_store(ld_off, memory_size(), phase);
1075 if (st != NULL)
1076 continue; // take one more trip around
1077 }
1078 }
1079
1080 // Load boxed value from result of valueOf() call is input parameter.
1081 if (this->is_Load() && ld_adr->is_AddP() &&
1082 (tp != NULL) && tp->is_ptr_to_boxed_value()) {
1083 intptr_t ignore = 0;
1084 Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore);
1085 if (base != NULL && base->is_Proj() &&
1086 base->as_Proj()->_con == TypeFunc::Parms &&
1087 base->in(0)->is_CallStaticJava() &&
1088 base->in(0)->as_CallStaticJava()->is_boxing_method()) {
1089 return base->in(0)->in(TypeFunc::Parms);
1090 }
1091 }
1092
1093 break;
1094 }
1095
1096 return NULL;
1097 }
1098
1099 //----------------------is_instance_field_load_with_local_phi------------------
1100 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
1101 if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl &&
1102 in(Address)->is_AddP() ) {
1103 const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr();
1104 // Only instances and boxed values.
1105 if( t_oop != NULL &&
1106 (t_oop->is_ptr_to_boxed_value() ||
1107 t_oop->is_known_instance_field()) &&
1108 t_oop->offset() != Type::OffsetBot &&
1109 t_oop->offset() != Type::OffsetTop) {
1110 return true;
1111 }
1112 }
1113 return false;
1114 }
1115
1116 //------------------------------Identity---------------------------------------
1117 // Loads are identity if previous store is to same address
1118 Node *LoadNode::Identity( PhaseTransform *phase ) {
1119 // If the previous store-maker is the right kind of Store, and the store is
1120 // to the same address, then we are equal to the value stored.
1121 Node* mem = in(Memory);
1122 Node* value = can_see_stored_value(mem, phase);
1123 if( value ) {
1124 // byte, short & char stores truncate naturally.
1125 // A load has to load the truncated value which requires
1126 // some sort of masking operation and that requires an
1127 // Ideal call instead of an Identity call.
1128 if (memory_size() < BytesPerInt) {
1129 // If the input to the store does not fit with the load's result type,
1130 // it must be truncated via an Ideal call.
1131 if (!phase->type(value)->higher_equal(phase->type(this)))
1132 return this;
1133 }
1134 // (This works even when value is a Con, but LoadNode::Value
1135 // usually runs first, producing the singleton type of the Con.)
1136 return value;
1137 }
1138
1139 // Search for an existing data phi which was generated before for the same
1140 // instance's field to avoid infinite generation of phis in a loop.
1141 Node *region = mem->in(0);
1142 if (is_instance_field_load_with_local_phi(region)) {
1143 const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr();
1144 int this_index = phase->C->get_alias_index(addr_t);
1145 int this_offset = addr_t->offset();
1146 int this_iid = addr_t->instance_id();
1147 if (!addr_t->is_known_instance() &&
1148 addr_t->is_ptr_to_boxed_value()) {
1149 // Use _idx of address base (could be Phi node) for boxed values.
1150 intptr_t ignore = 0;
1151 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1152 this_iid = base->_idx;
1153 }
1154 const Type* this_type = bottom_type();
1155 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1156 Node* phi = region->fast_out(i);
1157 if (phi->is_Phi() && phi != mem &&
1158 phi->as_Phi()->is_same_inst_field(this_type, (int)mem->_idx, this_iid, this_index, this_offset)) {
1159 return phi;
1160 }
1161 }
1162 }
1163
1164 return this;
1165 }
1166
1167 // We're loading from an object which has autobox behaviour.
1168 // If this object is result of a valueOf call we'll have a phi
1169 // merging a newly allocated object and a load from the cache.
1170 // We want to replace this load with the original incoming
1171 // argument to the valueOf call.
1172 Node* LoadNode::eliminate_autobox(PhaseGVN* phase) {
1173 assert(phase->C->eliminate_boxing(), "sanity");
1174 intptr_t ignore = 0;
1175 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1176 if ((base == NULL) || base->is_Phi()) {
1177 // Push the loads from the phi that comes from valueOf up
1178 // through it to allow elimination of the loads and the recovery
1179 // of the original value. It is done in split_through_phi().
1180 return NULL;
1181 } else if (base->is_Load() ||
1182 base->is_DecodeN() && base->in(1)->is_Load()) {
1183 // Eliminate the load of boxed value for integer types from the cache
1184 // array by deriving the value from the index into the array.
1185 // Capture the offset of the load and then reverse the computation.
1186
1187 // Get LoadN node which loads a boxing object from 'cache' array.
1188 if (base->is_DecodeN()) {
1189 base = base->in(1);
1190 }
1191 if (!base->in(Address)->is_AddP()) {
1192 return NULL; // Complex address
1193 }
1194 AddPNode* address = base->in(Address)->as_AddP();
1195 Node* cache_base = address->in(AddPNode::Base);
1196 if ((cache_base != NULL) && cache_base->is_DecodeN()) {
1197 // Get ConP node which is static 'cache' field.
1198 cache_base = cache_base->in(1);
1199 }
1200 if ((cache_base != NULL) && cache_base->is_Con()) {
1201 const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr();
1202 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1203 Node* elements[4];
1204 int shift = exact_log2(type2aelembytes(T_OBJECT));
1205 int count = address->unpack_offsets(elements, ARRAY_SIZE(elements));
1206 if ((count > 0) && elements[0]->is_Con() &&
1207 ((count == 1) ||
1208 (count == 2) && elements[1]->Opcode() == Op_LShiftX &&
1209 elements[1]->in(2) == phase->intcon(shift))) {
1210 ciObjArray* array = base_type->const_oop()->as_obj_array();
1211 // Fetch the box object cache[0] at the base of the array and get its value
1212 ciInstance* box = array->obj_at(0)->as_instance();
1213 ciInstanceKlass* ik = box->klass()->as_instance_klass();
1214 assert(ik->is_box_klass(), "sanity");
1215 assert(ik->nof_nonstatic_fields() == 1, "change following code");
1216 if (ik->nof_nonstatic_fields() == 1) {
1217 // This should be true nonstatic_field_at requires calling
1218 // nof_nonstatic_fields so check it anyway
1219 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1220 BasicType bt = c.basic_type();
1221 // Only integer types have boxing cache.
1222 assert(bt == T_BOOLEAN || bt == T_CHAR ||
1223 bt == T_BYTE || bt == T_SHORT ||
1224 bt == T_INT || bt == T_LONG, err_msg_res("wrong type = %s", type2name(bt)));
1225 jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int();
1226 if (cache_low != (int)cache_low) {
1227 return NULL; // should not happen since cache is array indexed by value
1228 }
1229 jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift);
1230 if (offset != (int)offset) {
1231 return NULL; // should not happen since cache is array indexed by value
1232 }
1233 // Add up all the offsets making of the address of the load
1234 Node* result = elements[0];
1235 for (int i = 1; i < count; i++) {
1236 result = phase->transform(new (phase->C) AddXNode(result, elements[i]));
1237 }
1238 // Remove the constant offset from the address and then
1239 result = phase->transform(new (phase->C) AddXNode(result, phase->MakeConX(-(int)offset)));
1240 // remove the scaling of the offset to recover the original index.
1241 if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) {
1242 // Peel the shift off directly but wrap it in a dummy node
1243 // since Ideal can't return existing nodes
1244 result = new (phase->C) RShiftXNode(result->in(1), phase->intcon(0));
1245 } else if (result->is_Add() && result->in(2)->is_Con() &&
1246 result->in(1)->Opcode() == Op_LShiftX &&
1247 result->in(1)->in(2) == phase->intcon(shift)) {
1248 // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z)
1249 // but for boxing cache access we know that X<<Z will not overflow
1250 // (there is range check) so we do this optimizatrion by hand here.
1251 Node* add_con = new (phase->C) RShiftXNode(result->in(2), phase->intcon(shift));
1252 result = new (phase->C) AddXNode(result->in(1)->in(1), phase->transform(add_con));
1253 } else {
1254 result = new (phase->C) RShiftXNode(result, phase->intcon(shift));
1255 }
1256 #ifdef _LP64
1257 if (bt != T_LONG) {
1258 result = new (phase->C) ConvL2INode(phase->transform(result));
1259 }
1260 #else
1261 if (bt == T_LONG) {
1262 result = new (phase->C) ConvI2LNode(phase->transform(result));
1263 }
1264 #endif
1265 // Boxing/unboxing can be done from signed & unsigned loads (e.g. LoadUB -> ... -> LoadB pair).
1266 // Need to preserve unboxing load type if it is unsigned.
1267 switch(this->Opcode()) {
1268 case Op_LoadUB:
1269 result = new (phase->C) AndINode(phase->transform(result), phase->intcon(0xFF));
1270 break;
1271 case Op_LoadUS:
1272 result = new (phase->C) AndINode(phase->transform(result), phase->intcon(0xFFFF));
1273 break;
1274 }
1275 return result;
1276 }
1277 }
1278 }
1279 }
1280 }
1281 return NULL;
1282 }
1283
1284 static bool stable_phi(PhiNode* phi, PhaseGVN *phase) {
1285 Node* region = phi->in(0);
1286 if (region == NULL) {
1287 return false; // Wait stable graph
1288 }
1289 uint cnt = phi->req();
1290 for (uint i = 1; i < cnt; i++) {
1291 Node* rc = region->in(i);
1292 if (rc == NULL || phase->type(rc) == Type::TOP)
1293 return false; // Wait stable graph
1294 Node* in = phi->in(i);
1295 if (in == NULL || phase->type(in) == Type::TOP)
1296 return false; // Wait stable graph
1297 }
1298 return true;
1299 }
1300 //------------------------------split_through_phi------------------------------
1301 // Split instance or boxed field load through Phi.
1302 Node *LoadNode::split_through_phi(PhaseGVN *phase) {
1303 Node* mem = in(Memory);
1304 Node* address = in(Address);
1305 const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr();
1306
1307 assert((t_oop != NULL) &&
1308 (t_oop->is_known_instance_field() ||
1309 t_oop->is_ptr_to_boxed_value()), "invalide conditions");
1310
1311 Compile* C = phase->C;
1312 intptr_t ignore = 0;
1313 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1314 bool base_is_phi = (base != NULL) && base->is_Phi();
1315 bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() &&
1316 (base != NULL) && (base == address->in(AddPNode::Base)) &&
1317 phase->type(base)->higher_equal(TypePtr::NOTNULL);
1318
1319 if (!((mem->is_Phi() || base_is_phi) &&
1320 (load_boxed_values || t_oop->is_known_instance_field()))) {
1321 return NULL; // memory is not Phi
1322 }
1323
1324 if (mem->is_Phi()) {
1325 if (!stable_phi(mem->as_Phi(), phase)) {
1326 return NULL; // Wait stable graph
1327 }
1328 uint cnt = mem->req();
1329 // Check for loop invariant memory.
1330 if (cnt == 3) {
1331 for (uint i = 1; i < cnt; i++) {
1332 Node* in = mem->in(i);
1333 Node* m = optimize_memory_chain(in, t_oop, this, phase);
1334 if (m == mem) {
1335 set_req(Memory, mem->in(cnt - i));
1336 return this; // made change
1337 }
1338 }
1339 }
1340 }
1341 if (base_is_phi) {
1342 if (!stable_phi(base->as_Phi(), phase)) {
1343 return NULL; // Wait stable graph
1344 }
1345 uint cnt = base->req();
1346 // Check for loop invariant memory.
1347 if (cnt == 3) {
1348 for (uint i = 1; i < cnt; i++) {
1349 if (base->in(i) == base) {
1350 return NULL; // Wait stable graph
1351 }
1352 }
1353 }
1354 }
1355
1356 bool load_boxed_phi = load_boxed_values && base_is_phi && (base->in(0) == mem->in(0));
1357
1358 // Split through Phi (see original code in loopopts.cpp).
1359 assert(C->have_alias_type(t_oop), "instance should have alias type");
1360
1361 // Do nothing here if Identity will find a value
1362 // (to avoid infinite chain of value phis generation).
1363 if (!phase->eqv(this, this->Identity(phase)))
1364 return NULL;
1365
1366 // Select Region to split through.
1367 Node* region;
1368 if (!base_is_phi) {
1369 assert(mem->is_Phi(), "sanity");
1370 region = mem->in(0);
1371 // Skip if the region dominates some control edge of the address.
1372 if (!MemNode::all_controls_dominate(address, region))
1373 return NULL;
1374 } else if (!mem->is_Phi()) {
1375 assert(base_is_phi, "sanity");
1376 region = base->in(0);
1377 // Skip if the region dominates some control edge of the memory.
1378 if (!MemNode::all_controls_dominate(mem, region))
1379 return NULL;
1380 } else if (base->in(0) != mem->in(0)) {
1381 assert(base_is_phi && mem->is_Phi(), "sanity");
1382 if (MemNode::all_controls_dominate(mem, base->in(0))) {
1383 region = base->in(0);
1384 } else if (MemNode::all_controls_dominate(address, mem->in(0))) {
1385 region = mem->in(0);
1386 } else {
1387 return NULL; // complex graph
1388 }
1389 } else {
1390 assert(base->in(0) == mem->in(0), "sanity");
1391 region = mem->in(0);
1392 }
1393
1394 const Type* this_type = this->bottom_type();
1395 int this_index = C->get_alias_index(t_oop);
1396 int this_offset = t_oop->offset();
1397 int this_iid = t_oop->instance_id();
1398 if (!t_oop->is_known_instance() && load_boxed_values) {
1399 // Use _idx of address base for boxed values.
1400 this_iid = base->_idx;
1401 }
1402 PhaseIterGVN* igvn = phase->is_IterGVN();
1403 Node* phi = new (C) PhiNode(region, this_type, NULL, mem->_idx, this_iid, this_index, this_offset);
1404 for (uint i = 1; i < region->req(); i++) {
1405 Node* x;
1406 Node* the_clone = NULL;
1407 if (region->in(i) == C->top()) {
1408 x = C->top(); // Dead path? Use a dead data op
1409 } else {
1410 x = this->clone(); // Else clone up the data op
1411 the_clone = x; // Remember for possible deletion.
1412 // Alter data node to use pre-phi inputs
1413 if (this->in(0) == region) {
1414 x->set_req(0, region->in(i));
1415 } else {
1416 x->set_req(0, NULL);
1417 }
1418 if (mem->is_Phi() && (mem->in(0) == region)) {
1419 x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone.
1420 }
1421 if (address->is_Phi() && address->in(0) == region) {
1422 x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone
1423 }
1424 if (base_is_phi && (base->in(0) == region)) {
1425 Node* base_x = base->in(i); // Clone address for loads from boxed objects.
1426 Node* adr_x = phase->transform(new (C) AddPNode(base_x,base_x,address->in(AddPNode::Offset)));
1427 x->set_req(Address, adr_x);
1428 }
1429 }
1430 // Check for a 'win' on some paths
1431 const Type *t = x->Value(igvn);
1432
1433 bool singleton = t->singleton();
1434
1435 // See comments in PhaseIdealLoop::split_thru_phi().
1436 if (singleton && t == Type::TOP) {
1437 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1438 }
1439
1440 if (singleton) {
1441 x = igvn->makecon(t);
1442 } else {
1443 // We now call Identity to try to simplify the cloned node.
1444 // Note that some Identity methods call phase->type(this).
1445 // Make sure that the type array is big enough for
1446 // our new node, even though we may throw the node away.
1447 // (This tweaking with igvn only works because x is a new node.)
1448 igvn->set_type(x, t);
1449 // If x is a TypeNode, capture any more-precise type permanently into Node
1450 // otherwise it will be not updated during igvn->transform since
1451 // igvn->type(x) is set to x->Value() already.
1452 x->raise_bottom_type(t);
1453 Node *y = x->Identity(igvn);
1454 if (y != x) {
1455 x = y;
1456 } else {
1457 y = igvn->hash_find_insert(x);
1458 if (y) {
1459 x = y;
1460 } else {
1461 // Else x is a new node we are keeping
1462 // We do not need register_new_node_with_optimizer
1463 // because set_type has already been called.
1464 igvn->_worklist.push(x);
1465 }
1466 }
1467 }
1468 if (x != the_clone && the_clone != NULL) {
1469 igvn->remove_dead_node(the_clone);
1470 }
1471 phi->set_req(i, x);
1472 }
1473 // Record Phi
1474 igvn->register_new_node_with_optimizer(phi);
1475 return phi;
1476 }
1477
1478 //------------------------------Ideal------------------------------------------
1479 // If the load is from Field memory and the pointer is non-null, it might be possible to
1480 // zero out the control input.
1481 // If the offset is constant and the base is an object allocation,
1482 // try to hook me up to the exact initializing store.
1483 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1484 Node* p = MemNode::Ideal_common(phase, can_reshape);
1485 if (p) return (p == NodeSentinel) ? NULL : p;
1486
1487 Node* ctrl = in(MemNode::Control);
1488 Node* address = in(MemNode::Address);
1489
1490 // Skip up past a SafePoint control. Cannot do this for Stores because
1491 // pointer stores & cardmarks must stay on the same side of a SafePoint.
1492 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint &&
1493 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw ) {
1494 ctrl = ctrl->in(0);
1495 set_req(MemNode::Control,ctrl);
1496 }
1497
1498 intptr_t ignore = 0;
1499 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1500 if (base != NULL
1501 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
1502 // Check for useless control edge in some common special cases
1503 if (in(MemNode::Control) != NULL
1504 && can_remove_control()
1505 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1506 && all_controls_dominate(base, phase->C->start())) {
1507 // A method-invariant, non-null address (constant or 'this' argument).
1508 set_req(MemNode::Control, NULL);
1509 }
1510 }
1511
1512 Node* mem = in(MemNode::Memory);
1513 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1514
1515 if (can_reshape && (addr_t != NULL)) {
1516 // try to optimize our memory input
1517 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase);
1518 if (opt_mem != mem) {
1519 set_req(MemNode::Memory, opt_mem);
1520 if (phase->type( opt_mem ) == Type::TOP) return NULL;
1521 return this;
1522 }
1523 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1524 if ((t_oop != NULL) &&
1525 (t_oop->is_known_instance_field() ||
1526 t_oop->is_ptr_to_boxed_value())) {
1527 PhaseIterGVN *igvn = phase->is_IterGVN();
1528 if (igvn != NULL && igvn->_worklist.member(opt_mem)) {
1529 // Delay this transformation until memory Phi is processed.
1530 phase->is_IterGVN()->_worklist.push(this);
1531 return NULL;
1532 }
1533 // Split instance field load through Phi.
1534 Node* result = split_through_phi(phase);
1535 if (result != NULL) return result;
1536
1537 if (t_oop->is_ptr_to_boxed_value()) {
1538 Node* result = eliminate_autobox(phase);
1539 if (result != NULL) return result;
1540 }
1541 }
1542 }
1543
1544 // Check for prior store with a different base or offset; make Load
1545 // independent. Skip through any number of them. Bail out if the stores
1546 // are in an endless dead cycle and report no progress. This is a key
1547 // transform for Reflection. However, if after skipping through the Stores
1548 // we can't then fold up against a prior store do NOT do the transform as
1549 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
1550 // array memory alive twice: once for the hoisted Load and again after the
1551 // bypassed Store. This situation only works if EVERYBODY who does
1552 // anti-dependence work knows how to bypass. I.e. we need all
1553 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
1554 // the alias index stuff. So instead, peek through Stores and IFF we can
1555 // fold up, do so.
1556 Node* prev_mem = find_previous_store(phase);
1557 // Steps (a), (b): Walk past independent stores to find an exact match.
1558 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) {
1559 // (c) See if we can fold up on the spot, but don't fold up here.
1560 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
1561 // just return a prior value, which is done by Identity calls.
1562 if (can_see_stored_value(prev_mem, phase)) {
1563 // Make ready for step (d):
1564 set_req(MemNode::Memory, prev_mem);
1565 return this;
1566 }
1567 }
1568
1569 return NULL; // No further progress
1570 }
1571
1572 // Helper to recognize certain Klass fields which are invariant across
1573 // some group of array types (e.g., int[] or all T[] where T < Object).
1574 const Type*
1575 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1576 ciKlass* klass) const {
1577 if (tkls->offset() == in_bytes(Klass::modifier_flags_offset())) {
1578 // The field is Klass::_modifier_flags. Return its (constant) value.
1579 // (Folds up the 2nd indirection in aClassConstant.getModifiers().)
1580 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags");
1581 return TypeInt::make(klass->modifier_flags());
1582 }
1583 if (tkls->offset() == in_bytes(Klass::access_flags_offset())) {
1584 // The field is Klass::_access_flags. Return its (constant) value.
1585 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1586 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags");
1587 return TypeInt::make(klass->access_flags());
1588 }
1589 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) {
1590 // The field is Klass::_layout_helper. Return its constant value if known.
1591 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper");
1592 return TypeInt::make(klass->layout_helper());
1593 }
1594
1595 // No match.
1596 return NULL;
1597 }
1598
1599 // Try to constant-fold a stable array element.
1600 static const Type* fold_stable_ary_elem(const TypeAryPtr* ary, int off, BasicType loadbt) {
1601 assert(ary->const_oop(), "array should be constant");
1602 assert(ary->is_stable(), "array should be stable");
1603
1604 // Decode the results of GraphKit::array_element_address.
1605 ciArray* aobj = ary->const_oop()->as_array();
1606 ciConstant con = aobj->element_value_by_offset(off);
1607
1608 if (con.basic_type() != T_ILLEGAL && !con.is_null_or_zero()) {
1609 const Type* con_type = Type::make_from_constant(con);
1610 if (con_type != NULL) {
1611 if (con_type->isa_aryptr()) {
1612 // Join with the array element type, in case it is also stable.
1613 int dim = ary->stable_dimension();
1614 con_type = con_type->is_aryptr()->cast_to_stable(true, dim-1);
1615 }
1616 if (loadbt == T_NARROWOOP && con_type->isa_oopptr()) {
1617 con_type = con_type->make_narrowoop();
1618 }
1619 #ifndef PRODUCT
1620 if (TraceIterativeGVN) {
1621 tty->print("FoldStableValues: array element [off=%d]: con_type=", off);
1622 con_type->dump(); tty->cr();
1623 }
1624 #endif //PRODUCT
1625 return con_type;
1626 }
1627 }
1628 return NULL;
1629 }
1630
1631 //------------------------------Value-----------------------------------------
1632 const Type *LoadNode::Value( PhaseTransform *phase ) const {
1633 // Either input is TOP ==> the result is TOP
1634 Node* mem = in(MemNode::Memory);
1635 const Type *t1 = phase->type(mem);
1636 if (t1 == Type::TOP) return Type::TOP;
1637 Node* adr = in(MemNode::Address);
1638 const TypePtr* tp = phase->type(adr)->isa_ptr();
1639 if (tp == NULL || tp->empty()) return Type::TOP;
1640 int off = tp->offset();
1641 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
1642 Compile* C = phase->C;
1643
1644 // Try to guess loaded type from pointer type
1645 if (tp->isa_aryptr()) {
1646 const TypeAryPtr* ary = tp->is_aryptr();
1647 const Type* t = ary->elem();
1648
1649 // Determine whether the reference is beyond the header or not, by comparing
1650 // the offset against the offset of the start of the array's data.
1651 // Different array types begin at slightly different offsets (12 vs. 16).
1652 // We choose T_BYTE as an example base type that is least restrictive
1653 // as to alignment, which will therefore produce the smallest
1654 // possible base offset.
1655 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
1656 const bool off_beyond_header = ((uint)off >= (uint)min_base_off);
1657
1658 // Try to constant-fold a stable array element.
1659 if (FoldStableValues && ary->is_stable() && ary->const_oop() != NULL) {
1660 // Make sure the reference is not into the header and the offset is constant
1661 if (off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) {
1662 const Type* con_type = fold_stable_ary_elem(ary, off, memory_type());
1663 if (con_type != NULL) {
1664 return con_type;
1665 }
1666 }
1667 }
1668
1669 // Don't do this for integer types. There is only potential profit if
1670 // the element type t is lower than _type; that is, for int types, if _type is
1671 // more restrictive than t. This only happens here if one is short and the other
1672 // char (both 16 bits), and in those cases we've made an intentional decision
1673 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
1674 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
1675 //
1676 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
1677 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
1678 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
1679 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
1680 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
1681 // In fact, that could have been the original type of p1, and p1 could have
1682 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
1683 // expression (LShiftL quux 3) independently optimized to the constant 8.
1684 if ((t->isa_int() == NULL) && (t->isa_long() == NULL)
1685 && (_type->isa_vect() == NULL)
1686 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
1687 // t might actually be lower than _type, if _type is a unique
1688 // concrete subclass of abstract class t.
1689 if (off_beyond_header) { // is the offset beyond the header?
1690 const Type* jt = t->join_speculative(_type);
1691 // In any case, do not allow the join, per se, to empty out the type.
1692 if (jt->empty() && !t->empty()) {
1693 // This can happen if a interface-typed array narrows to a class type.
1694 jt = _type;
1695 }
1696 #ifdef ASSERT
1697 if (phase->C->eliminate_boxing() && adr->is_AddP()) {
1698 // The pointers in the autobox arrays are always non-null
1699 Node* base = adr->in(AddPNode::Base);
1700 if ((base != NULL) && base->is_DecodeN()) {
1701 // Get LoadN node which loads IntegerCache.cache field
1702 base = base->in(1);
1703 }
1704 if ((base != NULL) && base->is_Con()) {
1705 const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr();
1706 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1707 // It could be narrow oop
1708 assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity");
1709 }
1710 }
1711 }
1712 #endif
1713 return jt;
1714 }
1715 }
1716 } else if (tp->base() == Type::InstPtr) {
1717 ciEnv* env = C->env();
1718 const TypeInstPtr* tinst = tp->is_instptr();
1719 ciKlass* klass = tinst->klass();
1720 assert( off != Type::OffsetBot ||
1721 // arrays can be cast to Objects
1722 tp->is_oopptr()->klass()->is_java_lang_Object() ||
1723 // unsafe field access may not have a constant offset
1724 C->has_unsafe_access(),
1725 "Field accesses must be precise" );
1726 // For oop loads, we expect the _type to be precise
1727 if (klass == env->String_klass() &&
1728 adr->is_AddP() && off != Type::OffsetBot) {
1729 // For constant Strings treat the final fields as compile time constants.
1730 Node* base = adr->in(AddPNode::Base);
1731 const TypeOopPtr* t = phase->type(base)->isa_oopptr();
1732 if (t != NULL && t->singleton()) {
1733 ciField* field = env->String_klass()->get_field_by_offset(off, false);
1734 if (field != NULL && field->is_final()) {
1735 ciObject* string = t->const_oop();
1736 ciConstant constant = string->as_instance()->field_value(field);
1737 if (constant.basic_type() == T_INT) {
1738 return TypeInt::make(constant.as_int());
1739 } else if (constant.basic_type() == T_ARRAY) {
1740 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
1741 return TypeNarrowOop::make_from_constant(constant.as_object(), true);
1742 } else {
1743 return TypeOopPtr::make_from_constant(constant.as_object(), true);
1744 }
1745 }
1746 }
1747 }
1748 }
1749 // Optimizations for constant objects
1750 ciObject* const_oop = tinst->const_oop();
1751 if (const_oop != NULL) {
1752 // For constant Boxed value treat the target field as a compile time constant.
1753 if (tinst->is_ptr_to_boxed_value()) {
1754 return tinst->get_const_boxed_value();
1755 } else
1756 // For constant CallSites treat the target field as a compile time constant.
1757 if (const_oop->is_call_site()) {
1758 ciCallSite* call_site = const_oop->as_call_site();
1759 ciField* field = call_site->klass()->as_instance_klass()->get_field_by_offset(off, /*is_static=*/ false);
1760 if (field != NULL && field->is_call_site_target()) {
1761 ciMethodHandle* target = call_site->get_target();
1762 if (target != NULL) { // just in case
1763 ciConstant constant(T_OBJECT, target);
1764 const Type* t;
1765 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
1766 t = TypeNarrowOop::make_from_constant(constant.as_object(), true);
1767 } else {
1768 t = TypeOopPtr::make_from_constant(constant.as_object(), true);
1769 }
1770 // Add a dependence for invalidation of the optimization.
1771 if (!call_site->is_constant_call_site()) {
1772 C->dependencies()->assert_call_site_target_value(call_site, target);
1773 }
1774 return t;
1775 }
1776 }
1777 }
1778 }
1779 } else if (tp->base() == Type::KlassPtr) {
1780 assert( off != Type::OffsetBot ||
1781 // arrays can be cast to Objects
1782 tp->is_klassptr()->klass()->is_java_lang_Object() ||
1783 // also allow array-loading from the primary supertype
1784 // array during subtype checks
1785 Opcode() == Op_LoadKlass,
1786 "Field accesses must be precise" );
1787 // For klass/static loads, we expect the _type to be precise
1788 }
1789
1790 const TypeKlassPtr *tkls = tp->isa_klassptr();
1791 if (tkls != NULL && !StressReflectiveCode) {
1792 ciKlass* klass = tkls->klass();
1793 if (klass->is_loaded() && tkls->klass_is_exact()) {
1794 // We are loading a field from a Klass metaobject whose identity
1795 // is known at compile time (the type is "exact" or "precise").
1796 // Check for fields we know are maintained as constants by the VM.
1797 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) {
1798 // The field is Klass::_super_check_offset. Return its (constant) value.
1799 // (Folds up type checking code.)
1800 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
1801 return TypeInt::make(klass->super_check_offset());
1802 }
1803 // Compute index into primary_supers array
1804 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1805 // Check for overflowing; use unsigned compare to handle the negative case.
1806 if( depth < ciKlass::primary_super_limit() ) {
1807 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1808 // (Folds up type checking code.)
1809 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1810 ciKlass *ss = klass->super_of_depth(depth);
1811 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1812 }
1813 const Type* aift = load_array_final_field(tkls, klass);
1814 if (aift != NULL) return aift;
1815 if (tkls->offset() == in_bytes(ArrayKlass::component_mirror_offset())
1816 && klass->is_array_klass()) {
1817 // The field is ArrayKlass::_component_mirror. Return its (constant) value.
1818 // (Folds up aClassConstant.getComponentType, common in Arrays.copyOf.)
1819 assert(Opcode() == Op_LoadP, "must load an oop from _component_mirror");
1820 return TypeInstPtr::make(klass->as_array_klass()->component_mirror());
1821 }
1822 if (tkls->offset() == in_bytes(Klass::java_mirror_offset())) {
1823 // The field is Klass::_java_mirror. Return its (constant) value.
1824 // (Folds up the 2nd indirection in anObjConstant.getClass().)
1825 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
1826 return TypeInstPtr::make(klass->java_mirror());
1827 }
1828 }
1829
1830 // We can still check if we are loading from the primary_supers array at a
1831 // shallow enough depth. Even though the klass is not exact, entries less
1832 // than or equal to its super depth are correct.
1833 if (klass->is_loaded() ) {
1834 ciType *inner = klass;
1835 while( inner->is_obj_array_klass() )
1836 inner = inner->as_obj_array_klass()->base_element_type();
1837 if( inner->is_instance_klass() &&
1838 !inner->as_instance_klass()->flags().is_interface() ) {
1839 // Compute index into primary_supers array
1840 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1841 // Check for overflowing; use unsigned compare to handle the negative case.
1842 if( depth < ciKlass::primary_super_limit() &&
1843 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case
1844 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1845 // (Folds up type checking code.)
1846 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1847 ciKlass *ss = klass->super_of_depth(depth);
1848 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1849 }
1850 }
1851 }
1852
1853 // If the type is enough to determine that the thing is not an array,
1854 // we can give the layout_helper a positive interval type.
1855 // This will help short-circuit some reflective code.
1856 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())
1857 && !klass->is_array_klass() // not directly typed as an array
1858 && !klass->is_interface() // specifically not Serializable & Cloneable
1859 && !klass->is_java_lang_Object() // not the supertype of all T[]
1860 ) {
1861 // Note: When interfaces are reliable, we can narrow the interface
1862 // test to (klass != Serializable && klass != Cloneable).
1863 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
1864 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
1865 // The key property of this type is that it folds up tests
1866 // for array-ness, since it proves that the layout_helper is positive.
1867 // Thus, a generic value like the basic object layout helper works fine.
1868 return TypeInt::make(min_size, max_jint, Type::WidenMin);
1869 }
1870 }
1871
1872 // If we are loading from a freshly-allocated object, produce a zero,
1873 // if the load is provably beyond the header of the object.
1874 // (Also allow a variable load from a fresh array to produce zero.)
1875 const TypeOopPtr *tinst = tp->isa_oopptr();
1876 bool is_instance = (tinst != NULL) && tinst->is_known_instance_field();
1877 bool is_boxed_value = (tinst != NULL) && tinst->is_ptr_to_boxed_value();
1878 if (ReduceFieldZeroing || is_instance || is_boxed_value) {
1879 Node* value = can_see_stored_value(mem,phase);
1880 if (value != NULL && value->is_Con()) {
1881 assert(value->bottom_type()->higher_equal(_type),"sanity");
1882 return value->bottom_type();
1883 }
1884 }
1885
1886 if (is_instance) {
1887 // If we have an instance type and our memory input is the
1888 // programs's initial memory state, there is no matching store,
1889 // so just return a zero of the appropriate type
1890 Node *mem = in(MemNode::Memory);
1891 if (mem->is_Parm() && mem->in(0)->is_Start()) {
1892 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
1893 return Type::get_zero_type(_type->basic_type());
1894 }
1895 }
1896 return _type;
1897 }
1898
1899 //------------------------------match_edge-------------------------------------
1900 // Do we Match on this edge index or not? Match only the address.
1901 uint LoadNode::match_edge(uint idx) const {
1902 return idx == MemNode::Address;
1903 }
1904
1905 //--------------------------LoadBNode::Ideal--------------------------------------
1906 //
1907 // If the previous store is to the same address as this load,
1908 // and the value stored was larger than a byte, replace this load
1909 // with the value stored truncated to a byte. If no truncation is
1910 // needed, the replacement is done in LoadNode::Identity().
1911 //
1912 Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1913 Node* mem = in(MemNode::Memory);
1914 Node* value = can_see_stored_value(mem,phase);
1915 if( value && !phase->type(value)->higher_equal( _type ) ) {
1916 Node *result = phase->transform( new (phase->C) LShiftINode(value, phase->intcon(24)) );
1917 return new (phase->C) RShiftINode(result, phase->intcon(24));
1918 }
1919 // Identity call will handle the case where truncation is not needed.
1920 return LoadNode::Ideal(phase, can_reshape);
1921 }
1922
1923 const Type* LoadBNode::Value(PhaseTransform *phase) const {
1924 Node* mem = in(MemNode::Memory);
1925 Node* value = can_see_stored_value(mem,phase);
1926 if (value != NULL && value->is_Con() &&
1927 !value->bottom_type()->higher_equal(_type)) {
1928 // If the input to the store does not fit with the load's result type,
1929 // it must be truncated. We can't delay until Ideal call since
1930 // a singleton Value is needed for split_thru_phi optimization.
1931 int con = value->get_int();
1932 return TypeInt::make((con << 24) >> 24);
1933 }
1934 return LoadNode::Value(phase);
1935 }
1936
1937 //--------------------------LoadUBNode::Ideal-------------------------------------
1938 //
1939 // If the previous store is to the same address as this load,
1940 // and the value stored was larger than a byte, replace this load
1941 // with the value stored truncated to a byte. If no truncation is
1942 // needed, the replacement is done in LoadNode::Identity().
1943 //
1944 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
1945 Node* mem = in(MemNode::Memory);
1946 Node* value = can_see_stored_value(mem, phase);
1947 if (value && !phase->type(value)->higher_equal(_type))
1948 return new (phase->C) AndINode(value, phase->intcon(0xFF));
1949 // Identity call will handle the case where truncation is not needed.
1950 return LoadNode::Ideal(phase, can_reshape);
1951 }
1952
1953 const Type* LoadUBNode::Value(PhaseTransform *phase) const {
1954 Node* mem = in(MemNode::Memory);
1955 Node* value = can_see_stored_value(mem,phase);
1956 if (value != NULL && value->is_Con() &&
1957 !value->bottom_type()->higher_equal(_type)) {
1958 // If the input to the store does not fit with the load's result type,
1959 // it must be truncated. We can't delay until Ideal call since
1960 // a singleton Value is needed for split_thru_phi optimization.
1961 int con = value->get_int();
1962 return TypeInt::make(con & 0xFF);
1963 }
1964 return LoadNode::Value(phase);
1965 }
1966
1967 //--------------------------LoadUSNode::Ideal-------------------------------------
1968 //
1969 // If the previous store is to the same address as this load,
1970 // and the value stored was larger than a char, replace this load
1971 // with the value stored truncated to a char. If no truncation is
1972 // needed, the replacement is done in LoadNode::Identity().
1973 //
1974 Node *LoadUSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1975 Node* mem = in(MemNode::Memory);
1976 Node* value = can_see_stored_value(mem,phase);
1977 if( value && !phase->type(value)->higher_equal( _type ) )
1978 return new (phase->C) AndINode(value,phase->intcon(0xFFFF));
1979 // Identity call will handle the case where truncation is not needed.
1980 return LoadNode::Ideal(phase, can_reshape);
1981 }
1982
1983 const Type* LoadUSNode::Value(PhaseTransform *phase) const {
1984 Node* mem = in(MemNode::Memory);
1985 Node* value = can_see_stored_value(mem,phase);
1986 if (value != NULL && value->is_Con() &&
1987 !value->bottom_type()->higher_equal(_type)) {
1988 // If the input to the store does not fit with the load's result type,
1989 // it must be truncated. We can't delay until Ideal call since
1990 // a singleton Value is needed for split_thru_phi optimization.
1991 int con = value->get_int();
1992 return TypeInt::make(con & 0xFFFF);
1993 }
1994 return LoadNode::Value(phase);
1995 }
1996
1997 //--------------------------LoadSNode::Ideal--------------------------------------
1998 //
1999 // If the previous store is to the same address as this load,
2000 // and the value stored was larger than a short, replace this load
2001 // with the value stored truncated to a short. If no truncation is
2002 // needed, the replacement is done in LoadNode::Identity().
2003 //
2004 Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2005 Node* mem = in(MemNode::Memory);
2006 Node* value = can_see_stored_value(mem,phase);
2007 if( value && !phase->type(value)->higher_equal( _type ) ) {
2008 Node *result = phase->transform( new (phase->C) LShiftINode(value, phase->intcon(16)) );
2009 return new (phase->C) RShiftINode(result, phase->intcon(16));
2010 }
2011 // Identity call will handle the case where truncation is not needed.
2012 return LoadNode::Ideal(phase, can_reshape);
2013 }
2014
2015 const Type* LoadSNode::Value(PhaseTransform *phase) const {
2016 Node* mem = in(MemNode::Memory);
2017 Node* value = can_see_stored_value(mem,phase);
2018 if (value != NULL && value->is_Con() &&
2019 !value->bottom_type()->higher_equal(_type)) {
2020 // If the input to the store does not fit with the load's result type,
2021 // it must be truncated. We can't delay until Ideal call since
2022 // a singleton Value is needed for split_thru_phi optimization.
2023 int con = value->get_int();
2024 return TypeInt::make((con << 16) >> 16);
2025 }
2026 return LoadNode::Value(phase);
2027 }
2028
2029 //=============================================================================
2030 //----------------------------LoadKlassNode::make------------------------------
2031 // Polymorphic factory method:
2032 Node* LoadKlassNode::make(PhaseGVN& gvn, Node* ctl, Node *mem, Node *adr, const TypePtr* at, const TypeKlassPtr *tk) {
2033 Compile* C = gvn.C;
2034 // sanity check the alias category against the created node type
2035 const TypePtr *adr_type = adr->bottom_type()->isa_ptr();
2036 assert(adr_type != NULL, "expecting TypeKlassPtr");
2037 #ifdef _LP64
2038 if (adr_type->is_ptr_to_narrowklass()) {
2039 assert(UseCompressedClassPointers, "no compressed klasses");
2040 Node* load_klass = gvn.transform(new (C) LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowklass(), MemNode::unordered));
2041 return new (C) DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr());
2042 }
2043 #endif
2044 assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
2045 return new (C) LoadKlassNode(ctl, mem, adr, at, tk, MemNode::unordered);
2046 }
2047
2048 //------------------------------Value------------------------------------------
2049 const Type *LoadKlassNode::Value( PhaseTransform *phase ) const {
2050 return klass_value_common(phase);
2051 }
2052
2053 // In most cases, LoadKlassNode does not have the control input set. If the control
2054 // input is set, it must not be removed (by LoadNode::Ideal()).
2055 bool LoadKlassNode::can_remove_control() const {
2056 return false;
2057 }
2058
2059 const Type *LoadNode::klass_value_common( PhaseTransform *phase ) const {
2060 // Either input is TOP ==> the result is TOP
2061 const Type *t1 = phase->type( in(MemNode::Memory) );
2062 if (t1 == Type::TOP) return Type::TOP;
2063 Node *adr = in(MemNode::Address);
2064 const Type *t2 = phase->type( adr );
2065 if (t2 == Type::TOP) return Type::TOP;
2066 const TypePtr *tp = t2->is_ptr();
2067 if (TypePtr::above_centerline(tp->ptr()) ||
2068 tp->ptr() == TypePtr::Null) return Type::TOP;
2069
2070 // Return a more precise klass, if possible
2071 const TypeInstPtr *tinst = tp->isa_instptr();
2072 if (tinst != NULL) {
2073 ciInstanceKlass* ik = tinst->klass()->as_instance_klass();
2074 int offset = tinst->offset();
2075 if (ik == phase->C->env()->Class_klass()
2076 && (offset == java_lang_Class::klass_offset_in_bytes() ||
2077 offset == java_lang_Class::array_klass_offset_in_bytes())) {
2078 // We are loading a special hidden field from a Class mirror object,
2079 // the field which points to the VM's Klass metaobject.
2080 ciType* t = tinst->java_mirror_type();
2081 // java_mirror_type returns non-null for compile-time Class constants.
2082 if (t != NULL) {
2083 // constant oop => constant klass
2084 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
2085 if (t->is_void()) {
2086 // We cannot create a void array. Since void is a primitive type return null
2087 // klass. Users of this result need to do a null check on the returned klass.
2088 return TypePtr::NULL_PTR;
2089 }
2090 return TypeKlassPtr::make(ciArrayKlass::make(t));
2091 }
2092 if (!t->is_klass()) {
2093 // a primitive Class (e.g., int.class) has NULL for a klass field
2094 return TypePtr::NULL_PTR;
2095 }
2096 // (Folds up the 1st indirection in aClassConstant.getModifiers().)
2097 return TypeKlassPtr::make(t->as_klass());
2098 }
2099 // non-constant mirror, so we can't tell what's going on
2100 }
2101 if( !ik->is_loaded() )
2102 return _type; // Bail out if not loaded
2103 if (offset == oopDesc::klass_offset_in_bytes()) {
2104 if (tinst->klass_is_exact()) {
2105 return TypeKlassPtr::make(ik);
2106 }
2107 // See if we can become precise: no subklasses and no interface
2108 // (Note: We need to support verified interfaces.)
2109 if (!ik->is_interface() && !ik->has_subklass()) {
2110 //assert(!UseExactTypes, "this code should be useless with exact types");
2111 // Add a dependence; if any subclass added we need to recompile
2112 if (!ik->is_final()) {
2113 // %%% should use stronger assert_unique_concrete_subtype instead
2114 phase->C->dependencies()->assert_leaf_type(ik);
2115 }
2116 // Return precise klass
2117 return TypeKlassPtr::make(ik);
2118 }
2119
2120 // Return root of possible klass
2121 return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/);
2122 }
2123 }
2124
2125 // Check for loading klass from an array
2126 const TypeAryPtr *tary = tp->isa_aryptr();
2127 if( tary != NULL ) {
2128 ciKlass *tary_klass = tary->klass();
2129 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP
2130 && tary->offset() == oopDesc::klass_offset_in_bytes()) {
2131 if (tary->klass_is_exact()) {
2132 return TypeKlassPtr::make(tary_klass);
2133 }
2134 ciArrayKlass *ak = tary->klass()->as_array_klass();
2135 // If the klass is an object array, we defer the question to the
2136 // array component klass.
2137 if( ak->is_obj_array_klass() ) {
2138 assert( ak->is_loaded(), "" );
2139 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass();
2140 if( base_k->is_loaded() && base_k->is_instance_klass() ) {
2141 ciInstanceKlass* ik = base_k->as_instance_klass();
2142 // See if we can become precise: no subklasses and no interface
2143 if (!ik->is_interface() && !ik->has_subklass()) {
2144 //assert(!UseExactTypes, "this code should be useless with exact types");
2145 // Add a dependence; if any subclass added we need to recompile
2146 if (!ik->is_final()) {
2147 phase->C->dependencies()->assert_leaf_type(ik);
2148 }
2149 // Return precise array klass
2150 return TypeKlassPtr::make(ak);
2151 }
2152 }
2153 return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/);
2154 } else { // Found a type-array?
2155 //assert(!UseExactTypes, "this code should be useless with exact types");
2156 assert( ak->is_type_array_klass(), "" );
2157 return TypeKlassPtr::make(ak); // These are always precise
2158 }
2159 }
2160 }
2161
2162 // Check for loading klass from an array klass
2163 const TypeKlassPtr *tkls = tp->isa_klassptr();
2164 if (tkls != NULL && !StressReflectiveCode) {
2165 ciKlass* klass = tkls->klass();
2166 if( !klass->is_loaded() )
2167 return _type; // Bail out if not loaded
2168 if( klass->is_obj_array_klass() &&
2169 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) {
2170 ciKlass* elem = klass->as_obj_array_klass()->element_klass();
2171 // // Always returning precise element type is incorrect,
2172 // // e.g., element type could be object and array may contain strings
2173 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
2174
2175 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
2176 // according to the element type's subclassing.
2177 return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/);
2178 }
2179 if( klass->is_instance_klass() && tkls->klass_is_exact() &&
2180 tkls->offset() == in_bytes(Klass::super_offset())) {
2181 ciKlass* sup = klass->as_instance_klass()->super();
2182 // The field is Klass::_super. Return its (constant) value.
2183 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
2184 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR;
2185 }
2186 }
2187
2188 // Bailout case
2189 return LoadNode::Value(phase);
2190 }
2191
2192 //------------------------------Identity---------------------------------------
2193 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
2194 // Also feed through the klass in Allocate(...klass...)._klass.
2195 Node* LoadKlassNode::Identity( PhaseTransform *phase ) {
2196 return klass_identity_common(phase);
2197 }
2198
2199 Node* LoadNode::klass_identity_common(PhaseTransform *phase ) {
2200 Node* x = LoadNode::Identity(phase);
2201 if (x != this) return x;
2202
2203 // Take apart the address into an oop and and offset.
2204 // Return 'this' if we cannot.
2205 Node* adr = in(MemNode::Address);
2206 intptr_t offset = 0;
2207 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2208 if (base == NULL) return this;
2209 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
2210 if (toop == NULL) return this;
2211
2212 // We can fetch the klass directly through an AllocateNode.
2213 // This works even if the klass is not constant (clone or newArray).
2214 if (offset == oopDesc::klass_offset_in_bytes()) {
2215 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
2216 if (allocated_klass != NULL) {
2217 return allocated_klass;
2218 }
2219 }
2220
2221 // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*.
2222 // Simplify ak.component_mirror.array_klass to plain ak, ak an ArrayKlass.
2223 // See inline_native_Class_query for occurrences of these patterns.
2224 // Java Example: x.getClass().isAssignableFrom(y)
2225 // Java Example: Array.newInstance(x.getClass().getComponentType(), n)
2226 //
2227 // This improves reflective code, often making the Class
2228 // mirror go completely dead. (Current exception: Class
2229 // mirrors may appear in debug info, but we could clean them out by
2230 // introducing a new debug info operator for Klass*.java_mirror).
2231 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass()
2232 && (offset == java_lang_Class::klass_offset_in_bytes() ||
2233 offset == java_lang_Class::array_klass_offset_in_bytes())) {
2234 // We are loading a special hidden field from a Class mirror,
2235 // the field which points to its Klass or ArrayKlass metaobject.
2236 if (base->is_Load()) {
2237 Node* adr2 = base->in(MemNode::Address);
2238 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2239 if (tkls != NULL && !tkls->empty()
2240 && (tkls->klass()->is_instance_klass() ||
2241 tkls->klass()->is_array_klass())
2242 && adr2->is_AddP()
2243 ) {
2244 int mirror_field = in_bytes(Klass::java_mirror_offset());
2245 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
2246 mirror_field = in_bytes(ArrayKlass::component_mirror_offset());
2247 }
2248 if (tkls->offset() == mirror_field) {
2249 return adr2->in(AddPNode::Base);
2250 }
2251 }
2252 }
2253 }
2254
2255 return this;
2256 }
2257
2258
2259 //------------------------------Value------------------------------------------
2260 const Type *LoadNKlassNode::Value( PhaseTransform *phase ) const {
2261 const Type *t = klass_value_common(phase);
2262 if (t == Type::TOP)
2263 return t;
2264
2265 return t->make_narrowklass();
2266 }
2267
2268 //------------------------------Identity---------------------------------------
2269 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
2270 // Also feed through the klass in Allocate(...klass...)._klass.
2271 Node* LoadNKlassNode::Identity( PhaseTransform *phase ) {
2272 Node *x = klass_identity_common(phase);
2273
2274 const Type *t = phase->type( x );
2275 if( t == Type::TOP ) return x;
2276 if( t->isa_narrowklass()) return x;
2277 assert (!t->isa_narrowoop(), "no narrow oop here");
2278
2279 return phase->transform(new (phase->C) EncodePKlassNode(x, t->make_narrowklass()));
2280 }
2281
2282 //------------------------------Value-----------------------------------------
2283 const Type *LoadRangeNode::Value( PhaseTransform *phase ) const {
2284 // Either input is TOP ==> the result is TOP
2285 const Type *t1 = phase->type( in(MemNode::Memory) );
2286 if( t1 == Type::TOP ) return Type::TOP;
2287 Node *adr = in(MemNode::Address);
2288 const Type *t2 = phase->type( adr );
2289 if( t2 == Type::TOP ) return Type::TOP;
2290 const TypePtr *tp = t2->is_ptr();
2291 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
2292 const TypeAryPtr *tap = tp->isa_aryptr();
2293 if( !tap ) return _type;
2294 return tap->size();
2295 }
2296
2297 //-------------------------------Ideal---------------------------------------
2298 // Feed through the length in AllocateArray(...length...)._length.
2299 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2300 Node* p = MemNode::Ideal_common(phase, can_reshape);
2301 if (p) return (p == NodeSentinel) ? NULL : p;
2302
2303 // Take apart the address into an oop and and offset.
2304 // Return 'this' if we cannot.
2305 Node* adr = in(MemNode::Address);
2306 intptr_t offset = 0;
2307 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2308 if (base == NULL) return NULL;
2309 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2310 if (tary == NULL) return NULL;
2311
2312 // We can fetch the length directly through an AllocateArrayNode.
2313 // This works even if the length is not constant (clone or newArray).
2314 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2315 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2316 if (alloc != NULL) {
2317 Node* allocated_length = alloc->Ideal_length();
2318 Node* len = alloc->make_ideal_length(tary, phase);
2319 if (allocated_length != len) {
2320 // New CastII improves on this.
2321 return len;
2322 }
2323 }
2324 }
2325
2326 return NULL;
2327 }
2328
2329 //------------------------------Identity---------------------------------------
2330 // Feed through the length in AllocateArray(...length...)._length.
2331 Node* LoadRangeNode::Identity( PhaseTransform *phase ) {
2332 Node* x = LoadINode::Identity(phase);
2333 if (x != this) return x;
2334
2335 // Take apart the address into an oop and and offset.
2336 // Return 'this' if we cannot.
2337 Node* adr = in(MemNode::Address);
2338 intptr_t offset = 0;
2339 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2340 if (base == NULL) return this;
2341 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2342 if (tary == NULL) return this;
2343
2344 // We can fetch the length directly through an AllocateArrayNode.
2345 // This works even if the length is not constant (clone or newArray).
2346 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2347 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2348 if (alloc != NULL) {
2349 Node* allocated_length = alloc->Ideal_length();
2350 // Do not allow make_ideal_length to allocate a CastII node.
2351 Node* len = alloc->make_ideal_length(tary, phase, false);
2352 if (allocated_length == len) {
2353 // Return allocated_length only if it would not be improved by a CastII.
2354 return allocated_length;
2355 }
2356 }
2357 }
2358
2359 return this;
2360
2361 }
2362
2363 //=============================================================================
2364 //---------------------------StoreNode::make-----------------------------------
2365 // Polymorphic factory method:
2366 StoreNode* StoreNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt, MemOrd mo) {
2367 assert((mo == unordered || mo == release), "unexpected");
2368 Compile* C = gvn.C;
2369 assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2370 ctl != NULL, "raw memory operations should have control edge");
2371
2372 switch (bt) {
2373 case T_BOOLEAN: val = gvn.transform(new (C) AndINode(val, gvn.intcon(0x1))); // Fall through to T_BYTE case
2374 case T_BYTE: return new (C) StoreBNode(ctl, mem, adr, adr_type, val, mo);
2375 case T_INT: return new (C) StoreINode(ctl, mem, adr, adr_type, val, mo);
2376 case T_CHAR:
2377 case T_SHORT: return new (C) StoreCNode(ctl, mem, adr, adr_type, val, mo);
2378 case T_LONG: return new (C) StoreLNode(ctl, mem, adr, adr_type, val, mo);
2379 case T_FLOAT: return new (C) StoreFNode(ctl, mem, adr, adr_type, val, mo);
2380 case T_DOUBLE: return new (C) StoreDNode(ctl, mem, adr, adr_type, val, mo);
2381 case T_METADATA:
2382 case T_ADDRESS:
2383 case T_OBJECT:
2384 #ifdef _LP64
2385 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
2386 val = gvn.transform(new (C) EncodePNode(val, val->bottom_type()->make_narrowoop()));
2387 return new (C) StoreNNode(ctl, mem, adr, adr_type, val, mo);
2388 } else if (adr->bottom_type()->is_ptr_to_narrowklass() ||
2389 (UseCompressedClassPointers && val->bottom_type()->isa_klassptr() &&
2390 adr->bottom_type()->isa_rawptr())) {
2391 val = gvn.transform(new (C) EncodePKlassNode(val, val->bottom_type()->make_narrowklass()));
2392 return new (C) StoreNKlassNode(ctl, mem, adr, adr_type, val, mo);
2393 }
2394 #endif
2395 {
2396 return new (C) StorePNode(ctl, mem, adr, adr_type, val, mo);
2397 }
2398 }
2399 ShouldNotReachHere();
2400 return (StoreNode*)NULL;
2401 }
2402
2403 StoreLNode* StoreLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
2404 bool require_atomic = true;
2405 return new (C) StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
2406 }
2407
2408 StoreDNode* StoreDNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
2409 bool require_atomic = true;
2410 return new (C) StoreDNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
2411 }
2412
2413
2414 //--------------------------bottom_type----------------------------------------
2415 const Type *StoreNode::bottom_type() const {
2416 return Type::MEMORY;
2417 }
2418
2419 //------------------------------hash-------------------------------------------
2420 uint StoreNode::hash() const {
2421 // unroll addition of interesting fields
2422 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2423
2424 // Since they are not commoned, do not hash them:
2425 return NO_HASH;
2426 }
2427
2428 //------------------------------Ideal------------------------------------------
2429 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
2430 // When a store immediately follows a relevant allocation/initialization,
2431 // try to capture it into the initialization, or hoist it above.
2432 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2433 Node* p = MemNode::Ideal_common(phase, can_reshape);
2434 if (p) return (p == NodeSentinel) ? NULL : p;
2435
2436 Node* mem = in(MemNode::Memory);
2437 Node* address = in(MemNode::Address);
2438
2439 // Back-to-back stores to same address? Fold em up. Generally
2440 // unsafe if I have intervening uses... Also disallowed for StoreCM
2441 // since they must follow each StoreP operation. Redundant StoreCMs
2442 // are eliminated just before matching in final_graph_reshape.
2443 if (mem->is_Store() && mem->in(MemNode::Address)->eqv_uncast(address) &&
2444 mem->Opcode() != Op_StoreCM) {
2445 // Looking at a dead closed cycle of memory?
2446 assert(mem != mem->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
2447
2448 assert(Opcode() == mem->Opcode() ||
2449 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw,
2450 "no mismatched stores, except on raw memory");
2451
2452 if (mem->outcnt() == 1 && // check for intervening uses
2453 mem->as_Store()->memory_size() <= this->memory_size()) {
2454 // If anybody other than 'this' uses 'mem', we cannot fold 'mem' away.
2455 // For example, 'mem' might be the final state at a conditional return.
2456 // Or, 'mem' might be used by some node which is live at the same time
2457 // 'this' is live, which might be unschedulable. So, require exactly
2458 // ONE user, the 'this' store, until such time as we clone 'mem' for
2459 // each of 'mem's uses (thus making the exactly-1-user-rule hold true).
2460 if (can_reshape) { // (%%% is this an anachronism?)
2461 set_req_X(MemNode::Memory, mem->in(MemNode::Memory),
2462 phase->is_IterGVN());
2463 } else {
2464 // It's OK to do this in the parser, since DU info is always accurate,
2465 // and the parser always refers to nodes via SafePointNode maps.
2466 set_req(MemNode::Memory, mem->in(MemNode::Memory));
2467 }
2468 return this;
2469 }
2470 }
2471
2472 // Capture an unaliased, unconditional, simple store into an initializer.
2473 // Or, if it is independent of the allocation, hoist it above the allocation.
2474 if (ReduceFieldZeroing && /*can_reshape &&*/
2475 mem->is_Proj() && mem->in(0)->is_Initialize()) {
2476 InitializeNode* init = mem->in(0)->as_Initialize();
2477 intptr_t offset = init->can_capture_store(this, phase, can_reshape);
2478 if (offset > 0) {
2479 Node* moved = init->capture_store(this, offset, phase, can_reshape);
2480 // If the InitializeNode captured me, it made a raw copy of me,
2481 // and I need to disappear.
2482 if (moved != NULL) {
2483 // %%% hack to ensure that Ideal returns a new node:
2484 mem = MergeMemNode::make(phase->C, mem);
2485 return mem; // fold me away
2486 }
2487 }
2488 }
2489
2490 return NULL; // No further progress
2491 }
2492
2493 //------------------------------Value-----------------------------------------
2494 const Type *StoreNode::Value( PhaseTransform *phase ) const {
2495 // Either input is TOP ==> the result is TOP
2496 const Type *t1 = phase->type( in(MemNode::Memory) );
2497 if( t1 == Type::TOP ) return Type::TOP;
2498 const Type *t2 = phase->type( in(MemNode::Address) );
2499 if( t2 == Type::TOP ) return Type::TOP;
2500 const Type *t3 = phase->type( in(MemNode::ValueIn) );
2501 if( t3 == Type::TOP ) return Type::TOP;
2502 return Type::MEMORY;
2503 }
2504
2505 //------------------------------Identity---------------------------------------
2506 // Remove redundant stores:
2507 // Store(m, p, Load(m, p)) changes to m.
2508 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
2509 Node *StoreNode::Identity( PhaseTransform *phase ) {
2510 Node* mem = in(MemNode::Memory);
2511 Node* adr = in(MemNode::Address);
2512 Node* val = in(MemNode::ValueIn);
2513
2514 // Load then Store? Then the Store is useless
2515 if (val->is_Load() &&
2516 val->in(MemNode::Address)->eqv_uncast(adr) &&
2517 val->in(MemNode::Memory )->eqv_uncast(mem) &&
2518 val->as_Load()->store_Opcode() == Opcode()) {
2519 return mem;
2520 }
2521
2522 // Two stores in a row of the same value?
2523 if (mem->is_Store() &&
2524 mem->in(MemNode::Address)->eqv_uncast(adr) &&
2525 mem->in(MemNode::ValueIn)->eqv_uncast(val) &&
2526 mem->Opcode() == Opcode()) {
2527 return mem;
2528 }
2529
2530 // Store of zero anywhere into a freshly-allocated object?
2531 // Then the store is useless.
2532 // (It must already have been captured by the InitializeNode.)
2533 if (ReduceFieldZeroing && phase->type(val)->is_zero_type()) {
2534 // a newly allocated object is already all-zeroes everywhere
2535 if (mem->is_Proj() && mem->in(0)->is_Allocate()) {
2536 return mem;
2537 }
2538
2539 // the store may also apply to zero-bits in an earlier object
2540 Node* prev_mem = find_previous_store(phase);
2541 // Steps (a), (b): Walk past independent stores to find an exact match.
2542 if (prev_mem != NULL) {
2543 Node* prev_val = can_see_stored_value(prev_mem, phase);
2544 if (prev_val != NULL && phase->eqv(prev_val, val)) {
2545 // prev_val and val might differ by a cast; it would be good
2546 // to keep the more informative of the two.
2547 return mem;
2548 }
2549 }
2550 }
2551
2552 return this;
2553 }
2554
2555 //------------------------------match_edge-------------------------------------
2556 // Do we Match on this edge index or not? Match only memory & value
2557 uint StoreNode::match_edge(uint idx) const {
2558 return idx == MemNode::Address || idx == MemNode::ValueIn;
2559 }
2560
2561 //------------------------------cmp--------------------------------------------
2562 // Do not common stores up together. They generally have to be split
2563 // back up anyways, so do not bother.
2564 uint StoreNode::cmp( const Node &n ) const {
2565 return (&n == this); // Always fail except on self
2566 }
2567
2568 //------------------------------Ideal_masked_input-----------------------------
2569 // Check for a useless mask before a partial-word store
2570 // (StoreB ... (AndI valIn conIa) )
2571 // If (conIa & mask == mask) this simplifies to
2572 // (StoreB ... (valIn) )
2573 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
2574 Node *val = in(MemNode::ValueIn);
2575 if( val->Opcode() == Op_AndI ) {
2576 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2577 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
2578 set_req(MemNode::ValueIn, val->in(1));
2579 return this;
2580 }
2581 }
2582 return NULL;
2583 }
2584
2585
2586 //------------------------------Ideal_sign_extended_input----------------------
2587 // Check for useless sign-extension before a partial-word store
2588 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) )
2589 // If (conIL == conIR && conIR <= num_bits) this simplifies to
2590 // (StoreB ... (valIn) )
2591 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) {
2592 Node *val = in(MemNode::ValueIn);
2593 if( val->Opcode() == Op_RShiftI ) {
2594 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2595 if( t && t->is_con() && (t->get_con() <= num_bits) ) {
2596 Node *shl = val->in(1);
2597 if( shl->Opcode() == Op_LShiftI ) {
2598 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int();
2599 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) {
2600 set_req(MemNode::ValueIn, shl->in(1));
2601 return this;
2602 }
2603 }
2604 }
2605 }
2606 return NULL;
2607 }
2608
2609 //------------------------------value_never_loaded-----------------------------------
2610 // Determine whether there are any possible loads of the value stored.
2611 // For simplicity, we actually check if there are any loads from the
2612 // address stored to, not just for loads of the value stored by this node.
2613 //
2614 bool StoreNode::value_never_loaded( PhaseTransform *phase) const {
2615 Node *adr = in(Address);
2616 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
2617 if (adr_oop == NULL)
2618 return false;
2619 if (!adr_oop->is_known_instance_field())
2620 return false; // if not a distinct instance, there may be aliases of the address
2621 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
2622 Node *use = adr->fast_out(i);
2623 int opc = use->Opcode();
2624 if (use->is_Load() || use->is_LoadStore()) {
2625 return false;
2626 }
2627 }
2628 return true;
2629 }
2630
2631 //=============================================================================
2632 //------------------------------Ideal------------------------------------------
2633 // If the store is from an AND mask that leaves the low bits untouched, then
2634 // we can skip the AND operation. If the store is from a sign-extension
2635 // (a left shift, then right shift) we can skip both.
2636 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
2637 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
2638 if( progress != NULL ) return progress;
2639
2640 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
2641 if( progress != NULL ) return progress;
2642
2643 // Finally check the default case
2644 return StoreNode::Ideal(phase, can_reshape);
2645 }
2646
2647 //=============================================================================
2648 //------------------------------Ideal------------------------------------------
2649 // If the store is from an AND mask that leaves the low bits untouched, then
2650 // we can skip the AND operation
2651 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
2652 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
2653 if( progress != NULL ) return progress;
2654
2655 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
2656 if( progress != NULL ) return progress;
2657
2658 // Finally check the default case
2659 return StoreNode::Ideal(phase, can_reshape);
2660 }
2661
2662 //=============================================================================
2663 //------------------------------Identity---------------------------------------
2664 Node *StoreCMNode::Identity( PhaseTransform *phase ) {
2665 // No need to card mark when storing a null ptr
2666 Node* my_store = in(MemNode::OopStore);
2667 if (my_store->is_Store()) {
2668 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) );
2669 if( t1 == TypePtr::NULL_PTR ) {
2670 return in(MemNode::Memory);
2671 }
2672 }
2673 return this;
2674 }
2675
2676 //=============================================================================
2677 //------------------------------Ideal---------------------------------------
2678 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){
2679 Node* progress = StoreNode::Ideal(phase, can_reshape);
2680 if (progress != NULL) return progress;
2681
2682 Node* my_store = in(MemNode::OopStore);
2683 if (my_store->is_MergeMem()) {
2684 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx());
2685 set_req(MemNode::OopStore, mem);
2686 return this;
2687 }
2688
2689 return NULL;
2690 }
2691
2692 //------------------------------Value-----------------------------------------
2693 const Type *StoreCMNode::Value( PhaseTransform *phase ) const {
2694 // Either input is TOP ==> the result is TOP
2695 const Type *t = phase->type( in(MemNode::Memory) );
2696 if( t == Type::TOP ) return Type::TOP;
2697 t = phase->type( in(MemNode::Address) );
2698 if( t == Type::TOP ) return Type::TOP;
2699 t = phase->type( in(MemNode::ValueIn) );
2700 if( t == Type::TOP ) return Type::TOP;
2701 // If extra input is TOP ==> the result is TOP
2702 t = phase->type( in(MemNode::OopStore) );
2703 if( t == Type::TOP ) return Type::TOP;
2704
2705 return StoreNode::Value( phase );
2706 }
2707
2708
2709 //=============================================================================
2710 //----------------------------------SCMemProjNode------------------------------
2711 const Type * SCMemProjNode::Value( PhaseTransform *phase ) const
2712 {
2713 return bottom_type();
2714 }
2715
2716 //=============================================================================
2717 //----------------------------------LoadStoreNode------------------------------
2718 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required )
2719 : Node(required),
2720 _type(rt),
2721 _adr_type(at)
2722 {
2723 init_req(MemNode::Control, c );
2724 init_req(MemNode::Memory , mem);
2725 init_req(MemNode::Address, adr);
2726 init_req(MemNode::ValueIn, val);
2727 init_class_id(Class_LoadStore);
2728 }
2729
2730 uint LoadStoreNode::ideal_reg() const {
2731 return _type->ideal_reg();
2732 }
2733
2734 bool LoadStoreNode::result_not_used() const {
2735 for( DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++ ) {
2736 Node *x = fast_out(i);
2737 if (x->Opcode() == Op_SCMemProj) continue;
2738 return false;
2739 }
2740 return true;
2741 }
2742
2743 uint LoadStoreNode::size_of() const { return sizeof(*this); }
2744
2745 //=============================================================================
2746 //----------------------------------LoadStoreConditionalNode--------------------
2747 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, NULL, TypeInt::BOOL, 5) {
2748 init_req(ExpectedIn, ex );
2749 }
2750
2751 //=============================================================================
2752 //-------------------------------adr_type--------------------------------------
2753 // Do we Match on this edge index or not? Do not match memory
2754 const TypePtr* ClearArrayNode::adr_type() const {
2755 Node *adr = in(3);
2756 return MemNode::calculate_adr_type(adr->bottom_type());
2757 }
2758
2759 //------------------------------match_edge-------------------------------------
2760 // Do we Match on this edge index or not? Do not match memory
2761 uint ClearArrayNode::match_edge(uint idx) const {
2762 return idx > 1;
2763 }
2764
2765 //------------------------------Identity---------------------------------------
2766 // Clearing a zero length array does nothing
2767 Node *ClearArrayNode::Identity( PhaseTransform *phase ) {
2768 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
2769 }
2770
2771 //------------------------------Idealize---------------------------------------
2772 // Clearing a short array is faster with stores
2773 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape){
2774 const int unit = BytesPerLong;
2775 const TypeX* t = phase->type(in(2))->isa_intptr_t();
2776 if (!t) return NULL;
2777 if (!t->is_con()) return NULL;
2778 intptr_t raw_count = t->get_con();
2779 intptr_t size = raw_count;
2780 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
2781 // Clearing nothing uses the Identity call.
2782 // Negative clears are possible on dead ClearArrays
2783 // (see jck test stmt114.stmt11402.val).
2784 if (size <= 0 || size % unit != 0) return NULL;
2785 intptr_t count = size / unit;
2786 // Length too long; use fast hardware clear
2787 if (size > Matcher::init_array_short_size) return NULL;
2788 Node *mem = in(1);
2789 if( phase->type(mem)==Type::TOP ) return NULL;
2790 Node *adr = in(3);
2791 const Type* at = phase->type(adr);
2792 if( at==Type::TOP ) return NULL;
2793 const TypePtr* atp = at->isa_ptr();
2794 // adjust atp to be the correct array element address type
2795 if (atp == NULL) atp = TypePtr::BOTTOM;
2796 else atp = atp->add_offset(Type::OffsetBot);
2797 // Get base for derived pointer purposes
2798 if( adr->Opcode() != Op_AddP ) Unimplemented();
2799 Node *base = adr->in(1);
2800
2801 Node *zero = phase->makecon(TypeLong::ZERO);
2802 Node *off = phase->MakeConX(BytesPerLong);
2803 mem = new (phase->C) StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
2804 count--;
2805 while( count-- ) {
2806 mem = phase->transform(mem);
2807 adr = phase->transform(new (phase->C) AddPNode(base,adr,off));
2808 mem = new (phase->C) StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
2809 }
2810 return mem;
2811 }
2812
2813 //----------------------------step_through----------------------------------
2814 // Return allocation input memory edge if it is different instance
2815 // or itself if it is the one we are looking for.
2816 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) {
2817 Node* n = *np;
2818 assert(n->is_ClearArray(), "sanity");
2819 intptr_t offset;
2820 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
2821 // This method is called only before Allocate nodes are expanded during
2822 // macro nodes expansion. Before that ClearArray nodes are only generated
2823 // in LibraryCallKit::generate_arraycopy() which follows allocations.
2824 assert(alloc != NULL, "should have allocation");
2825 if (alloc->_idx == instance_id) {
2826 // Can not bypass initialization of the instance we are looking for.
2827 return false;
2828 }
2829 // Otherwise skip it.
2830 InitializeNode* init = alloc->initialization();
2831 if (init != NULL)
2832 *np = init->in(TypeFunc::Memory);
2833 else
2834 *np = alloc->in(TypeFunc::Memory);
2835 return true;
2836 }
2837
2838 //----------------------------clear_memory-------------------------------------
2839 // Generate code to initialize object storage to zero.
2840 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2841 intptr_t start_offset,
2842 Node* end_offset,
2843 PhaseGVN* phase) {
2844 Compile* C = phase->C;
2845 intptr_t offset = start_offset;
2846
2847 int unit = BytesPerLong;
2848 if ((offset % unit) != 0) {
2849 Node* adr = new (C) AddPNode(dest, dest, phase->MakeConX(offset));
2850 adr = phase->transform(adr);
2851 const TypePtr* atp = TypeRawPtr::BOTTOM;
2852 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
2853 mem = phase->transform(mem);
2854 offset += BytesPerInt;
2855 }
2856 assert((offset % unit) == 0, "");
2857
2858 // Initialize the remaining stuff, if any, with a ClearArray.
2859 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase);
2860 }
2861
2862 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2863 Node* start_offset,
2864 Node* end_offset,
2865 PhaseGVN* phase) {
2866 if (start_offset == end_offset) {
2867 // nothing to do
2868 return mem;
2869 }
2870
2871 Compile* C = phase->C;
2872 int unit = BytesPerLong;
2873 Node* zbase = start_offset;
2874 Node* zend = end_offset;
2875
2876 // Scale to the unit required by the CPU:
2877 if (!Matcher::init_array_count_is_in_bytes) {
2878 Node* shift = phase->intcon(exact_log2(unit));
2879 zbase = phase->transform( new(C) URShiftXNode(zbase, shift) );
2880 zend = phase->transform( new(C) URShiftXNode(zend, shift) );
2881 }
2882
2883 // Bulk clear double-words
2884 Node* zsize = phase->transform( new(C) SubXNode(zend, zbase) );
2885 Node* adr = phase->transform( new(C) AddPNode(dest, dest, start_offset) );
2886 mem = new (C) ClearArrayNode(ctl, mem, zsize, adr);
2887 return phase->transform(mem);
2888 }
2889
2890 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2891 intptr_t start_offset,
2892 intptr_t end_offset,
2893 PhaseGVN* phase) {
2894 if (start_offset == end_offset) {
2895 // nothing to do
2896 return mem;
2897 }
2898
2899 Compile* C = phase->C;
2900 assert((end_offset % BytesPerInt) == 0, "odd end offset");
2901 intptr_t done_offset = end_offset;
2902 if ((done_offset % BytesPerLong) != 0) {
2903 done_offset -= BytesPerInt;
2904 }
2905 if (done_offset > start_offset) {
2906 mem = clear_memory(ctl, mem, dest,
2907 start_offset, phase->MakeConX(done_offset), phase);
2908 }
2909 if (done_offset < end_offset) { // emit the final 32-bit store
2910 Node* adr = new (C) AddPNode(dest, dest, phase->MakeConX(done_offset));
2911 adr = phase->transform(adr);
2912 const TypePtr* atp = TypeRawPtr::BOTTOM;
2913 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
2914 mem = phase->transform(mem);
2915 done_offset += BytesPerInt;
2916 }
2917 assert(done_offset == end_offset, "");
2918 return mem;
2919 }
2920
2921 //=============================================================================
2922 // Do not match memory edge.
2923 uint StrIntrinsicNode::match_edge(uint idx) const {
2924 return idx == 2 || idx == 3;
2925 }
2926
2927 //------------------------------Ideal------------------------------------------
2928 // Return a node which is more "ideal" than the current node. Strip out
2929 // control copies
2930 Node *StrIntrinsicNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2931 if (remove_dead_region(phase, can_reshape)) return this;
2932 // Don't bother trying to transform a dead node
2933 if (in(0) && in(0)->is_top()) return NULL;
2934
2935 if (can_reshape) {
2936 Node* mem = phase->transform(in(MemNode::Memory));
2937 // If transformed to a MergeMem, get the desired slice
2938 uint alias_idx = phase->C->get_alias_index(adr_type());
2939 mem = mem->is_MergeMem() ? mem->as_MergeMem()->memory_at(alias_idx) : mem;
2940 if (mem != in(MemNode::Memory)) {
2941 set_req(MemNode::Memory, mem);
2942 return this;
2943 }
2944 }
2945 return NULL;
2946 }
2947
2948 //------------------------------Value------------------------------------------
2949 const Type *StrIntrinsicNode::Value( PhaseTransform *phase ) const {
2950 if (in(0) && phase->type(in(0)) == Type::TOP) return Type::TOP;
2951 return bottom_type();
2952 }
2953
2954 //=============================================================================
2955 //------------------------------match_edge-------------------------------------
2956 // Do not match memory edge
2957 uint EncodeISOArrayNode::match_edge(uint idx) const {
2958 return idx == 2 || idx == 3; // EncodeISOArray src (Binary dst len)
2959 }
2960
2961 //------------------------------Ideal------------------------------------------
2962 // Return a node which is more "ideal" than the current node. Strip out
2963 // control copies
2964 Node *EncodeISOArrayNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2965 return remove_dead_region(phase, can_reshape) ? this : NULL;
2966 }
2967
2968 //------------------------------Value------------------------------------------
2969 const Type *EncodeISOArrayNode::Value(PhaseTransform *phase) const {
2970 if (in(0) && phase->type(in(0)) == Type::TOP) return Type::TOP;
2971 return bottom_type();
2972 }
2973
2974 //=============================================================================
2975 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
2976 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)),
2977 _adr_type(C->get_adr_type(alias_idx))
2978 {
2979 init_class_id(Class_MemBar);
2980 Node* top = C->top();
2981 init_req(TypeFunc::I_O,top);
2982 init_req(TypeFunc::FramePtr,top);
2983 init_req(TypeFunc::ReturnAdr,top);
2984 if (precedent != NULL)
2985 init_req(TypeFunc::Parms, precedent);
2986 }
2987
2988 //------------------------------cmp--------------------------------------------
2989 uint MemBarNode::hash() const { return NO_HASH; }
2990 uint MemBarNode::cmp( const Node &n ) const {
2991 return (&n == this); // Always fail except on self
2992 }
2993
2994 //------------------------------make-------------------------------------------
2995 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
2996 switch (opcode) {
2997 case Op_MemBarAcquire: return new(C) MemBarAcquireNode(C, atp, pn);
2998 case Op_LoadFence: return new(C) LoadFenceNode(C, atp, pn);
2999 case Op_MemBarRelease: return new(C) MemBarReleaseNode(C, atp, pn);
3000 case Op_StoreFence: return new(C) StoreFenceNode(C, atp, pn);
3001 case Op_MemBarAcquireLock: return new(C) MemBarAcquireLockNode(C, atp, pn);
3002 case Op_MemBarReleaseLock: return new(C) MemBarReleaseLockNode(C, atp, pn);
3003 case Op_MemBarVolatile: return new(C) MemBarVolatileNode(C, atp, pn);
3004 case Op_MemBarCPUOrder: return new(C) MemBarCPUOrderNode(C, atp, pn);
3005 case Op_Initialize: return new(C) InitializeNode(C, atp, pn);
3006 case Op_MemBarStoreStore: return new(C) MemBarStoreStoreNode(C, atp, pn);
3007 default: ShouldNotReachHere(); return NULL;
3008 }
3009 }
3010
3011 //------------------------------Ideal------------------------------------------
3012 // Return a node which is more "ideal" than the current node. Strip out
3013 // control copies
3014 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3015 if (remove_dead_region(phase, can_reshape)) return this;
3016 // Don't bother trying to transform a dead node
3017 if (in(0) && in(0)->is_top()) {
3018 return NULL;
3019 }
3020
3021 // Eliminate volatile MemBars for scalar replaced objects.
3022 if (can_reshape && req() == (Precedent+1)) {
3023 bool eliminate = false;
3024 int opc = Opcode();
3025 if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) {
3026 // Volatile field loads and stores.
3027 Node* my_mem = in(MemBarNode::Precedent);
3028 // The MembarAquire may keep an unused LoadNode alive through the Precedent edge
3029 if ((my_mem != NULL) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) {
3030 // if the Precedent is a decodeN and its input (a Load) is used at more than one place,
3031 // replace this Precedent (decodeN) with the Load instead.
3032 if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1)) {
3033 Node* load_node = my_mem->in(1);
3034 set_req(MemBarNode::Precedent, load_node);
3035 phase->is_IterGVN()->_worklist.push(my_mem);
3036 my_mem = load_node;
3037 } else {
3038 assert(my_mem->unique_out() == this, "sanity");
3039 del_req(Precedent);
3040 phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later
3041 my_mem = NULL;
3042 }
3043 }
3044 if (my_mem != NULL && my_mem->is_Mem()) {
3045 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
3046 // Check for scalar replaced object reference.
3047 if( t_oop != NULL && t_oop->is_known_instance_field() &&
3048 t_oop->offset() != Type::OffsetBot &&
3049 t_oop->offset() != Type::OffsetTop) {
3050 eliminate = true;
3051 }
3052 }
3053 } else if (opc == Op_MemBarRelease) {
3054 // Final field stores.
3055 Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent), phase);
3056 if ((alloc != NULL) && alloc->is_Allocate() &&
3057 alloc->as_Allocate()->_is_non_escaping) {
3058 // The allocated object does not escape.
3059 eliminate = true;
3060 }
3061 }
3062 if (eliminate) {
3063 // Replace MemBar projections by its inputs.
3064 PhaseIterGVN* igvn = phase->is_IterGVN();
3065 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
3066 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
3067 // Must return either the original node (now dead) or a new node
3068 // (Do not return a top here, since that would break the uniqueness of top.)
3069 return new (phase->C) ConINode(TypeInt::ZERO);
3070 }
3071 }
3072 return NULL;
3073 }
3074
3075 //------------------------------Value------------------------------------------
3076 const Type *MemBarNode::Value( PhaseTransform *phase ) const {
3077 if( !in(0) ) return Type::TOP;
3078 if( phase->type(in(0)) == Type::TOP )
3079 return Type::TOP;
3080 return TypeTuple::MEMBAR;
3081 }
3082
3083 //------------------------------match------------------------------------------
3084 // Construct projections for memory.
3085 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) {
3086 switch (proj->_con) {
3087 case TypeFunc::Control:
3088 case TypeFunc::Memory:
3089 return new (m->C) MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
3090 }
3091 ShouldNotReachHere();
3092 return NULL;
3093 }
3094
3095 //===========================InitializeNode====================================
3096 // SUMMARY:
3097 // This node acts as a memory barrier on raw memory, after some raw stores.
3098 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
3099 // The Initialize can 'capture' suitably constrained stores as raw inits.
3100 // It can coalesce related raw stores into larger units (called 'tiles').
3101 // It can avoid zeroing new storage for memory units which have raw inits.
3102 // At macro-expansion, it is marked 'complete', and does not optimize further.
3103 //
3104 // EXAMPLE:
3105 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
3106 // ctl = incoming control; mem* = incoming memory
3107 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
3108 // First allocate uninitialized memory and fill in the header:
3109 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
3110 // ctl := alloc.Control; mem* := alloc.Memory*
3111 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
3112 // Then initialize to zero the non-header parts of the raw memory block:
3113 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
3114 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
3115 // After the initialize node executes, the object is ready for service:
3116 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
3117 // Suppose its body is immediately initialized as {1,2}:
3118 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3119 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3120 // mem.SLICE(#short[*]) := store2
3121 //
3122 // DETAILS:
3123 // An InitializeNode collects and isolates object initialization after
3124 // an AllocateNode and before the next possible safepoint. As a
3125 // memory barrier (MemBarNode), it keeps critical stores from drifting
3126 // down past any safepoint or any publication of the allocation.
3127 // Before this barrier, a newly-allocated object may have uninitialized bits.
3128 // After this barrier, it may be treated as a real oop, and GC is allowed.
3129 //
3130 // The semantics of the InitializeNode include an implicit zeroing of
3131 // the new object from object header to the end of the object.
3132 // (The object header and end are determined by the AllocateNode.)
3133 //
3134 // Certain stores may be added as direct inputs to the InitializeNode.
3135 // These stores must update raw memory, and they must be to addresses
3136 // derived from the raw address produced by AllocateNode, and with
3137 // a constant offset. They must be ordered by increasing offset.
3138 // The first one is at in(RawStores), the last at in(req()-1).
3139 // Unlike most memory operations, they are not linked in a chain,
3140 // but are displayed in parallel as users of the rawmem output of
3141 // the allocation.
3142 //
3143 // (See comments in InitializeNode::capture_store, which continue
3144 // the example given above.)
3145 //
3146 // When the associated Allocate is macro-expanded, the InitializeNode
3147 // may be rewritten to optimize collected stores. A ClearArrayNode
3148 // may also be created at that point to represent any required zeroing.
3149 // The InitializeNode is then marked 'complete', prohibiting further
3150 // capturing of nearby memory operations.
3151 //
3152 // During macro-expansion, all captured initializations which store
3153 // constant values of 32 bits or smaller are coalesced (if advantageous)
3154 // into larger 'tiles' 32 or 64 bits. This allows an object to be
3155 // initialized in fewer memory operations. Memory words which are
3156 // covered by neither tiles nor non-constant stores are pre-zeroed
3157 // by explicit stores of zero. (The code shape happens to do all
3158 // zeroing first, then all other stores, with both sequences occurring
3159 // in order of ascending offsets.)
3160 //
3161 // Alternatively, code may be inserted between an AllocateNode and its
3162 // InitializeNode, to perform arbitrary initialization of the new object.
3163 // E.g., the object copying intrinsics insert complex data transfers here.
3164 // The initialization must then be marked as 'complete' disable the
3165 // built-in zeroing semantics and the collection of initializing stores.
3166 //
3167 // While an InitializeNode is incomplete, reads from the memory state
3168 // produced by it are optimizable if they match the control edge and
3169 // new oop address associated with the allocation/initialization.
3170 // They return a stored value (if the offset matches) or else zero.
3171 // A write to the memory state, if it matches control and address,
3172 // and if it is to a constant offset, may be 'captured' by the
3173 // InitializeNode. It is cloned as a raw memory operation and rewired
3174 // inside the initialization, to the raw oop produced by the allocation.
3175 // Operations on addresses which are provably distinct (e.g., to
3176 // other AllocateNodes) are allowed to bypass the initialization.
3177 //
3178 // The effect of all this is to consolidate object initialization
3179 // (both arrays and non-arrays, both piecewise and bulk) into a
3180 // single location, where it can be optimized as a unit.
3181 //
3182 // Only stores with an offset less than TrackedInitializationLimit words
3183 // will be considered for capture by an InitializeNode. This puts a
3184 // reasonable limit on the complexity of optimized initializations.
3185
3186 //---------------------------InitializeNode------------------------------------
3187 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
3188 : _is_complete(Incomplete), _does_not_escape(false),
3189 MemBarNode(C, adr_type, rawoop)
3190 {
3191 init_class_id(Class_Initialize);
3192
3193 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
3194 assert(in(RawAddress) == rawoop, "proper init");
3195 // Note: allocation() can be NULL, for secondary initialization barriers
3196 }
3197
3198 // Since this node is not matched, it will be processed by the
3199 // register allocator. Declare that there are no constraints
3200 // on the allocation of the RawAddress edge.
3201 const RegMask &InitializeNode::in_RegMask(uint idx) const {
3202 // This edge should be set to top, by the set_complete. But be conservative.
3203 if (idx == InitializeNode::RawAddress)
3204 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
3205 return RegMask::Empty;
3206 }
3207
3208 Node* InitializeNode::memory(uint alias_idx) {
3209 Node* mem = in(Memory);
3210 if (mem->is_MergeMem()) {
3211 return mem->as_MergeMem()->memory_at(alias_idx);
3212 } else {
3213 // incoming raw memory is not split
3214 return mem;
3215 }
3216 }
3217
3218 bool InitializeNode::is_non_zero() {
3219 if (is_complete()) return false;
3220 remove_extra_zeroes();
3221 return (req() > RawStores);
3222 }
3223
3224 void InitializeNode::set_complete(PhaseGVN* phase) {
3225 assert(!is_complete(), "caller responsibility");
3226 _is_complete = Complete;
3227
3228 // After this node is complete, it contains a bunch of
3229 // raw-memory initializations. There is no need for
3230 // it to have anything to do with non-raw memory effects.
3231 // Therefore, tell all non-raw users to re-optimize themselves,
3232 // after skipping the memory effects of this initialization.
3233 PhaseIterGVN* igvn = phase->is_IterGVN();
3234 if (igvn) igvn->add_users_to_worklist(this);
3235 }
3236
3237 // convenience function
3238 // return false if the init contains any stores already
3239 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
3240 InitializeNode* init = initialization();
3241 if (init == NULL || init->is_complete()) return false;
3242 init->remove_extra_zeroes();
3243 // for now, if this allocation has already collected any inits, bail:
3244 if (init->is_non_zero()) return false;
3245 init->set_complete(phase);
3246 return true;
3247 }
3248
3249 void InitializeNode::remove_extra_zeroes() {
3250 if (req() == RawStores) return;
3251 Node* zmem = zero_memory();
3252 uint fill = RawStores;
3253 for (uint i = fill; i < req(); i++) {
3254 Node* n = in(i);
3255 if (n->is_top() || n == zmem) continue; // skip
3256 if (fill < i) set_req(fill, n); // compact
3257 ++fill;
3258 }
3259 // delete any empty spaces created:
3260 while (fill < req()) {
3261 del_req(fill);
3262 }
3263 }
3264
3265 // Helper for remembering which stores go with which offsets.
3266 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) {
3267 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
3268 intptr_t offset = -1;
3269 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
3270 phase, offset);
3271 if (base == NULL) return -1; // something is dead,
3272 if (offset < 0) return -1; // dead, dead
3273 return offset;
3274 }
3275
3276 // Helper for proving that an initialization expression is
3277 // "simple enough" to be folded into an object initialization.
3278 // Attempts to prove that a store's initial value 'n' can be captured
3279 // within the initialization without creating a vicious cycle, such as:
3280 // { Foo p = new Foo(); p.next = p; }
3281 // True for constants and parameters and small combinations thereof.
3282 bool InitializeNode::detect_init_independence(Node* n, int& count) {
3283 if (n == NULL) return true; // (can this really happen?)
3284 if (n->is_Proj()) n = n->in(0);
3285 if (n == this) return false; // found a cycle
3286 if (n->is_Con()) return true;
3287 if (n->is_Start()) return true; // params, etc., are OK
3288 if (n->is_Root()) return true; // even better
3289
3290 Node* ctl = n->in(0);
3291 if (ctl != NULL && !ctl->is_top()) {
3292 if (ctl->is_Proj()) ctl = ctl->in(0);
3293 if (ctl == this) return false;
3294
3295 // If we already know that the enclosing memory op is pinned right after
3296 // the init, then any control flow that the store has picked up
3297 // must have preceded the init, or else be equal to the init.
3298 // Even after loop optimizations (which might change control edges)
3299 // a store is never pinned *before* the availability of its inputs.
3300 if (!MemNode::all_controls_dominate(n, this))
3301 return false; // failed to prove a good control
3302 }
3303
3304 // Check data edges for possible dependencies on 'this'.
3305 if ((count += 1) > 20) return false; // complexity limit
3306 for (uint i = 1; i < n->req(); i++) {
3307 Node* m = n->in(i);
3308 if (m == NULL || m == n || m->is_top()) continue;
3309 uint first_i = n->find_edge(m);
3310 if (i != first_i) continue; // process duplicate edge just once
3311 if (!detect_init_independence(m, count)) {
3312 return false;
3313 }
3314 }
3315
3316 return true;
3317 }
3318
3319 // Here are all the checks a Store must pass before it can be moved into
3320 // an initialization. Returns zero if a check fails.
3321 // On success, returns the (constant) offset to which the store applies,
3322 // within the initialized memory.
3323 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase, bool can_reshape) {
3324 const int FAIL = 0;
3325 if (st->req() != MemNode::ValueIn + 1)
3326 return FAIL; // an inscrutable StoreNode (card mark?)
3327 Node* ctl = st->in(MemNode::Control);
3328 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this))
3329 return FAIL; // must be unconditional after the initialization
3330 Node* mem = st->in(MemNode::Memory);
3331 if (!(mem->is_Proj() && mem->in(0) == this))
3332 return FAIL; // must not be preceded by other stores
3333 Node* adr = st->in(MemNode::Address);
3334 intptr_t offset;
3335 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
3336 if (alloc == NULL)
3337 return FAIL; // inscrutable address
3338 if (alloc != allocation())
3339 return FAIL; // wrong allocation! (store needs to float up)
3340 Node* val = st->in(MemNode::ValueIn);
3341 int complexity_count = 0;
3342 if (!detect_init_independence(val, complexity_count))
3343 return FAIL; // stored value must be 'simple enough'
3344
3345 // The Store can be captured only if nothing after the allocation
3346 // and before the Store is using the memory location that the store
3347 // overwrites.
3348 bool failed = false;
3349 // If is_complete_with_arraycopy() is true the shape of the graph is
3350 // well defined and is safe so no need for extra checks.
3351 if (!is_complete_with_arraycopy()) {
3352 // We are going to look at each use of the memory state following
3353 // the allocation to make sure nothing reads the memory that the
3354 // Store writes.
3355 const TypePtr* t_adr = phase->type(adr)->isa_ptr();
3356 int alias_idx = phase->C->get_alias_index(t_adr);
3357 ResourceMark rm;
3358 Unique_Node_List mems;
3359 mems.push(mem);
3360 Node* unique_merge = NULL;
3361 for (uint next = 0; next < mems.size(); ++next) {
3362 Node *m = mems.at(next);
3363 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
3364 Node *n = m->fast_out(j);
3365 if (n->outcnt() == 0) {
3366 continue;
3367 }
3368 if (n == st) {
3369 continue;
3370 } else if (n->in(0) != NULL && n->in(0) != ctl) {
3371 // If the control of this use is different from the control
3372 // of the Store which is right after the InitializeNode then
3373 // this node cannot be between the InitializeNode and the
3374 // Store.
3375 continue;
3376 } else if (n->is_MergeMem()) {
3377 if (n->as_MergeMem()->memory_at(alias_idx) == m) {
3378 // We can hit a MergeMemNode (that will likely go away
3379 // later) that is a direct use of the memory state
3380 // following the InitializeNode on the same slice as the
3381 // store node that we'd like to capture. We need to check
3382 // the uses of the MergeMemNode.
3383 mems.push(n);
3384 }
3385 } else if (n->is_Mem()) {
3386 Node* other_adr = n->in(MemNode::Address);
3387 if (other_adr == adr) {
3388 failed = true;
3389 break;
3390 } else {
3391 const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr();
3392 if (other_t_adr != NULL) {
3393 int other_alias_idx = phase->C->get_alias_index(other_t_adr);
3394 if (other_alias_idx == alias_idx) {
3395 // A load from the same memory slice as the store right
3396 // after the InitializeNode. We check the control of the
3397 // object/array that is loaded from. If it's the same as
3398 // the store control then we cannot capture the store.
3399 assert(!n->is_Store(), "2 stores to same slice on same control?");
3400 Node* base = other_adr;
3401 assert(base->is_AddP(), err_msg_res("should be addp but is %s", base->Name()));
3402 base = base->in(AddPNode::Base);
3403 if (base != NULL) {
3404 base = base->uncast();
3405 if (base->is_Proj() && base->in(0) == alloc) {
3406 failed = true;
3407 break;
3408 }
3409 }
3410 }
3411 }
3412 }
3413 } else {
3414 failed = true;
3415 break;
3416 }
3417 }
3418 }
3419 }
3420 if (failed) {
3421 if (!can_reshape) {
3422 // We decided we couldn't capture the store during parsing. We
3423 // should try again during the next IGVN once the graph is
3424 // cleaner.
3425 phase->C->record_for_igvn(st);
3426 }
3427 return FAIL;
3428 }
3429
3430 return offset; // success
3431 }
3432
3433 // Find the captured store in(i) which corresponds to the range
3434 // [start..start+size) in the initialized object.
3435 // If there is one, return its index i. If there isn't, return the
3436 // negative of the index where it should be inserted.
3437 // Return 0 if the queried range overlaps an initialization boundary
3438 // or if dead code is encountered.
3439 // If size_in_bytes is zero, do not bother with overlap checks.
3440 int InitializeNode::captured_store_insertion_point(intptr_t start,
3441 int size_in_bytes,
3442 PhaseTransform* phase) {
3443 const int FAIL = 0, MAX_STORE = BytesPerLong;
3444
3445 if (is_complete())
3446 return FAIL; // arraycopy got here first; punt
3447
3448 assert(allocation() != NULL, "must be present");
3449
3450 // no negatives, no header fields:
3451 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
3452
3453 // after a certain size, we bail out on tracking all the stores:
3454 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3455 if (start >= ti_limit) return FAIL;
3456
3457 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
3458 if (i >= limit) return -(int)i; // not found; here is where to put it
3459
3460 Node* st = in(i);
3461 intptr_t st_off = get_store_offset(st, phase);
3462 if (st_off < 0) {
3463 if (st != zero_memory()) {
3464 return FAIL; // bail out if there is dead garbage
3465 }
3466 } else if (st_off > start) {
3467 // ...we are done, since stores are ordered
3468 if (st_off < start + size_in_bytes) {
3469 return FAIL; // the next store overlaps
3470 }
3471 return -(int)i; // not found; here is where to put it
3472 } else if (st_off < start) {
3473 if (size_in_bytes != 0 &&
3474 start < st_off + MAX_STORE &&
3475 start < st_off + st->as_Store()->memory_size()) {
3476 return FAIL; // the previous store overlaps
3477 }
3478 } else {
3479 if (size_in_bytes != 0 &&
3480 st->as_Store()->memory_size() != size_in_bytes) {
3481 return FAIL; // mismatched store size
3482 }
3483 return i;
3484 }
3485
3486 ++i;
3487 }
3488 }
3489
3490 // Look for a captured store which initializes at the offset 'start'
3491 // with the given size. If there is no such store, and no other
3492 // initialization interferes, then return zero_memory (the memory
3493 // projection of the AllocateNode).
3494 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
3495 PhaseTransform* phase) {
3496 assert(stores_are_sane(phase), "");
3497 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3498 if (i == 0) {
3499 return NULL; // something is dead
3500 } else if (i < 0) {
3501 return zero_memory(); // just primordial zero bits here
3502 } else {
3503 Node* st = in(i); // here is the store at this position
3504 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
3505 return st;
3506 }
3507 }
3508
3509 // Create, as a raw pointer, an address within my new object at 'offset'.
3510 Node* InitializeNode::make_raw_address(intptr_t offset,
3511 PhaseTransform* phase) {
3512 Node* addr = in(RawAddress);
3513 if (offset != 0) {
3514 Compile* C = phase->C;
3515 addr = phase->transform( new (C) AddPNode(C->top(), addr,
3516 phase->MakeConX(offset)) );
3517 }
3518 return addr;
3519 }
3520
3521 // Clone the given store, converting it into a raw store
3522 // initializing a field or element of my new object.
3523 // Caller is responsible for retiring the original store,
3524 // with subsume_node or the like.
3525 //
3526 // From the example above InitializeNode::InitializeNode,
3527 // here are the old stores to be captured:
3528 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3529 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3530 //
3531 // Here is the changed code; note the extra edges on init:
3532 // alloc = (Allocate ...)
3533 // rawoop = alloc.RawAddress
3534 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
3535 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
3536 // init = (Initialize alloc.Control alloc.Memory rawoop
3537 // rawstore1 rawstore2)
3538 //
3539 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
3540 PhaseTransform* phase, bool can_reshape) {
3541 assert(stores_are_sane(phase), "");
3542
3543 if (start < 0) return NULL;
3544 assert(can_capture_store(st, phase, can_reshape) == start, "sanity");
3545
3546 Compile* C = phase->C;
3547 int size_in_bytes = st->memory_size();
3548 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3549 if (i == 0) return NULL; // bail out
3550 Node* prev_mem = NULL; // raw memory for the captured store
3551 if (i > 0) {
3552 prev_mem = in(i); // there is a pre-existing store under this one
3553 set_req(i, C->top()); // temporarily disconnect it
3554 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
3555 } else {
3556 i = -i; // no pre-existing store
3557 prev_mem = zero_memory(); // a slice of the newly allocated object
3558 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
3559 set_req(--i, C->top()); // reuse this edge; it has been folded away
3560 else
3561 ins_req(i, C->top()); // build a new edge
3562 }
3563 Node* new_st = st->clone();
3564 new_st->set_req(MemNode::Control, in(Control));
3565 new_st->set_req(MemNode::Memory, prev_mem);
3566 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
3567 new_st = phase->transform(new_st);
3568
3569 // At this point, new_st might have swallowed a pre-existing store
3570 // at the same offset, or perhaps new_st might have disappeared,
3571 // if it redundantly stored the same value (or zero to fresh memory).
3572
3573 // In any case, wire it in:
3574 set_req(i, new_st);
3575
3576 // The caller may now kill the old guy.
3577 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
3578 assert(check_st == new_st || check_st == NULL, "must be findable");
3579 assert(!is_complete(), "");
3580 return new_st;
3581 }
3582
3583 static bool store_constant(jlong* tiles, int num_tiles,
3584 intptr_t st_off, int st_size,
3585 jlong con) {
3586 if ((st_off & (st_size-1)) != 0)
3587 return false; // strange store offset (assume size==2**N)
3588 address addr = (address)tiles + st_off;
3589 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
3590 switch (st_size) {
3591 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
3592 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
3593 case sizeof(jint): *(jint*) addr = (jint) con; break;
3594 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
3595 default: return false; // strange store size (detect size!=2**N here)
3596 }
3597 return true; // return success to caller
3598 }
3599
3600 // Coalesce subword constants into int constants and possibly
3601 // into long constants. The goal, if the CPU permits,
3602 // is to initialize the object with a small number of 64-bit tiles.
3603 // Also, convert floating-point constants to bit patterns.
3604 // Non-constants are not relevant to this pass.
3605 //
3606 // In terms of the running example on InitializeNode::InitializeNode
3607 // and InitializeNode::capture_store, here is the transformation
3608 // of rawstore1 and rawstore2 into rawstore12:
3609 // alloc = (Allocate ...)
3610 // rawoop = alloc.RawAddress
3611 // tile12 = 0x00010002
3612 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
3613 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
3614 //
3615 void
3616 InitializeNode::coalesce_subword_stores(intptr_t header_size,
3617 Node* size_in_bytes,
3618 PhaseGVN* phase) {
3619 Compile* C = phase->C;
3620
3621 assert(stores_are_sane(phase), "");
3622 // Note: After this pass, they are not completely sane,
3623 // since there may be some overlaps.
3624
3625 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
3626
3627 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3628 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
3629 size_limit = MIN2(size_limit, ti_limit);
3630 size_limit = align_size_up(size_limit, BytesPerLong);
3631 int num_tiles = size_limit / BytesPerLong;
3632
3633 // allocate space for the tile map:
3634 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
3635 jlong tiles_buf[small_len];
3636 Node* nodes_buf[small_len];
3637 jlong inits_buf[small_len];
3638 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
3639 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3640 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
3641 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
3642 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
3643 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3644 // tiles: exact bitwise model of all primitive constants
3645 // nodes: last constant-storing node subsumed into the tiles model
3646 // inits: which bytes (in each tile) are touched by any initializations
3647
3648 //// Pass A: Fill in the tile model with any relevant stores.
3649
3650 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
3651 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
3652 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
3653 Node* zmem = zero_memory(); // initially zero memory state
3654 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3655 Node* st = in(i);
3656 intptr_t st_off = get_store_offset(st, phase);
3657
3658 // Figure out the store's offset and constant value:
3659 if (st_off < header_size) continue; //skip (ignore header)
3660 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
3661 int st_size = st->as_Store()->memory_size();
3662 if (st_off + st_size > size_limit) break;
3663
3664 // Record which bytes are touched, whether by constant or not.
3665 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
3666 continue; // skip (strange store size)
3667
3668 const Type* val = phase->type(st->in(MemNode::ValueIn));
3669 if (!val->singleton()) continue; //skip (non-con store)
3670 BasicType type = val->basic_type();
3671
3672 jlong con = 0;
3673 switch (type) {
3674 case T_INT: con = val->is_int()->get_con(); break;
3675 case T_LONG: con = val->is_long()->get_con(); break;
3676 case T_FLOAT: con = jint_cast(val->getf()); break;
3677 case T_DOUBLE: con = jlong_cast(val->getd()); break;
3678 default: continue; //skip (odd store type)
3679 }
3680
3681 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
3682 st->Opcode() == Op_StoreL) {
3683 continue; // This StoreL is already optimal.
3684 }
3685
3686 // Store down the constant.
3687 store_constant(tiles, num_tiles, st_off, st_size, con);
3688
3689 intptr_t j = st_off >> LogBytesPerLong;
3690
3691 if (type == T_INT && st_size == BytesPerInt
3692 && (st_off & BytesPerInt) == BytesPerInt) {
3693 jlong lcon = tiles[j];
3694 if (!Matcher::isSimpleConstant64(lcon) &&
3695 st->Opcode() == Op_StoreI) {
3696 // This StoreI is already optimal by itself.
3697 jint* intcon = (jint*) &tiles[j];
3698 intcon[1] = 0; // undo the store_constant()
3699
3700 // If the previous store is also optimal by itself, back up and
3701 // undo the action of the previous loop iteration... if we can.
3702 // But if we can't, just let the previous half take care of itself.
3703 st = nodes[j];
3704 st_off -= BytesPerInt;
3705 con = intcon[0];
3706 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) {
3707 assert(st_off >= header_size, "still ignoring header");
3708 assert(get_store_offset(st, phase) == st_off, "must be");
3709 assert(in(i-1) == zmem, "must be");
3710 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
3711 assert(con == tcon->is_int()->get_con(), "must be");
3712 // Undo the effects of the previous loop trip, which swallowed st:
3713 intcon[0] = 0; // undo store_constant()
3714 set_req(i-1, st); // undo set_req(i, zmem)
3715 nodes[j] = NULL; // undo nodes[j] = st
3716 --old_subword; // undo ++old_subword
3717 }
3718 continue; // This StoreI is already optimal.
3719 }
3720 }
3721
3722 // This store is not needed.
3723 set_req(i, zmem);
3724 nodes[j] = st; // record for the moment
3725 if (st_size < BytesPerLong) // something has changed
3726 ++old_subword; // includes int/float, but who's counting...
3727 else ++old_long;
3728 }
3729
3730 if ((old_subword + old_long) == 0)
3731 return; // nothing more to do
3732
3733 //// Pass B: Convert any non-zero tiles into optimal constant stores.
3734 // Be sure to insert them before overlapping non-constant stores.
3735 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
3736 for (int j = 0; j < num_tiles; j++) {
3737 jlong con = tiles[j];
3738 jlong init = inits[j];
3739 if (con == 0) continue;
3740 jint con0, con1; // split the constant, address-wise
3741 jint init0, init1; // split the init map, address-wise
3742 { union { jlong con; jint intcon[2]; } u;
3743 u.con = con;
3744 con0 = u.intcon[0];
3745 con1 = u.intcon[1];
3746 u.con = init;
3747 init0 = u.intcon[0];
3748 init1 = u.intcon[1];
3749 }
3750
3751 Node* old = nodes[j];
3752 assert(old != NULL, "need the prior store");
3753 intptr_t offset = (j * BytesPerLong);
3754
3755 bool split = !Matcher::isSimpleConstant64(con);
3756
3757 if (offset < header_size) {
3758 assert(offset + BytesPerInt >= header_size, "second int counts");
3759 assert(*(jint*)&tiles[j] == 0, "junk in header");
3760 split = true; // only the second word counts
3761 // Example: int a[] = { 42 ... }
3762 } else if (con0 == 0 && init0 == -1) {
3763 split = true; // first word is covered by full inits
3764 // Example: int a[] = { ... foo(), 42 ... }
3765 } else if (con1 == 0 && init1 == -1) {
3766 split = true; // second word is covered by full inits
3767 // Example: int a[] = { ... 42, foo() ... }
3768 }
3769
3770 // Here's a case where init0 is neither 0 nor -1:
3771 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
3772 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
3773 // In this case the tile is not split; it is (jlong)42.
3774 // The big tile is stored down, and then the foo() value is inserted.
3775 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
3776
3777 Node* ctl = old->in(MemNode::Control);
3778 Node* adr = make_raw_address(offset, phase);
3779 const TypePtr* atp = TypeRawPtr::BOTTOM;
3780
3781 // One or two coalesced stores to plop down.
3782 Node* st[2];
3783 intptr_t off[2];
3784 int nst = 0;
3785 if (!split) {
3786 ++new_long;
3787 off[nst] = offset;
3788 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3789 phase->longcon(con), T_LONG, MemNode::unordered);
3790 } else {
3791 // Omit either if it is a zero.
3792 if (con0 != 0) {
3793 ++new_int;
3794 off[nst] = offset;
3795 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3796 phase->intcon(con0), T_INT, MemNode::unordered);
3797 }
3798 if (con1 != 0) {
3799 ++new_int;
3800 offset += BytesPerInt;
3801 adr = make_raw_address(offset, phase);
3802 off[nst] = offset;
3803 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3804 phase->intcon(con1), T_INT, MemNode::unordered);
3805 }
3806 }
3807
3808 // Insert second store first, then the first before the second.
3809 // Insert each one just before any overlapping non-constant stores.
3810 while (nst > 0) {
3811 Node* st1 = st[--nst];
3812 C->copy_node_notes_to(st1, old);
3813 st1 = phase->transform(st1);
3814 offset = off[nst];
3815 assert(offset >= header_size, "do not smash header");
3816 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
3817 guarantee(ins_idx != 0, "must re-insert constant store");
3818 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
3819 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
3820 set_req(--ins_idx, st1);
3821 else
3822 ins_req(ins_idx, st1);
3823 }
3824 }
3825
3826 if (PrintCompilation && WizardMode)
3827 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
3828 old_subword, old_long, new_int, new_long);
3829 if (C->log() != NULL)
3830 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
3831 old_subword, old_long, new_int, new_long);
3832
3833 // Clean up any remaining occurrences of zmem:
3834 remove_extra_zeroes();
3835 }
3836
3837 // Explore forward from in(start) to find the first fully initialized
3838 // word, and return its offset. Skip groups of subword stores which
3839 // together initialize full words. If in(start) is itself part of a
3840 // fully initialized word, return the offset of in(start). If there
3841 // are no following full-word stores, or if something is fishy, return
3842 // a negative value.
3843 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
3844 int int_map = 0;
3845 intptr_t int_map_off = 0;
3846 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
3847
3848 for (uint i = start, limit = req(); i < limit; i++) {
3849 Node* st = in(i);
3850
3851 intptr_t st_off = get_store_offset(st, phase);
3852 if (st_off < 0) break; // return conservative answer
3853
3854 int st_size = st->as_Store()->memory_size();
3855 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
3856 return st_off; // we found a complete word init
3857 }
3858
3859 // update the map:
3860
3861 intptr_t this_int_off = align_size_down(st_off, BytesPerInt);
3862 if (this_int_off != int_map_off) {
3863 // reset the map:
3864 int_map = 0;
3865 int_map_off = this_int_off;
3866 }
3867
3868 int subword_off = st_off - this_int_off;
3869 int_map |= right_n_bits(st_size) << subword_off;
3870 if ((int_map & FULL_MAP) == FULL_MAP) {
3871 return this_int_off; // we found a complete word init
3872 }
3873
3874 // Did this store hit or cross the word boundary?
3875 intptr_t next_int_off = align_size_down(st_off + st_size, BytesPerInt);
3876 if (next_int_off == this_int_off + BytesPerInt) {
3877 // We passed the current int, without fully initializing it.
3878 int_map_off = next_int_off;
3879 int_map >>= BytesPerInt;
3880 } else if (next_int_off > this_int_off + BytesPerInt) {
3881 // We passed the current and next int.
3882 return this_int_off + BytesPerInt;
3883 }
3884 }
3885
3886 return -1;
3887 }
3888
3889
3890 // Called when the associated AllocateNode is expanded into CFG.
3891 // At this point, we may perform additional optimizations.
3892 // Linearize the stores by ascending offset, to make memory
3893 // activity as coherent as possible.
3894 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
3895 intptr_t header_size,
3896 Node* size_in_bytes,
3897 PhaseGVN* phase) {
3898 assert(!is_complete(), "not already complete");
3899 assert(stores_are_sane(phase), "");
3900 assert(allocation() != NULL, "must be present");
3901
3902 remove_extra_zeroes();
3903
3904 if (ReduceFieldZeroing || ReduceBulkZeroing)
3905 // reduce instruction count for common initialization patterns
3906 coalesce_subword_stores(header_size, size_in_bytes, phase);
3907
3908 Node* zmem = zero_memory(); // initially zero memory state
3909 Node* inits = zmem; // accumulating a linearized chain of inits
3910 #ifdef ASSERT
3911 intptr_t first_offset = allocation()->minimum_header_size();
3912 intptr_t last_init_off = first_offset; // previous init offset
3913 intptr_t last_init_end = first_offset; // previous init offset+size
3914 intptr_t last_tile_end = first_offset; // previous tile offset+size
3915 #endif
3916 intptr_t zeroes_done = header_size;
3917
3918 bool do_zeroing = true; // we might give up if inits are very sparse
3919 int big_init_gaps = 0; // how many large gaps have we seen?
3920
3921 if (ZeroTLAB) do_zeroing = false;
3922 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
3923
3924 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3925 Node* st = in(i);
3926 intptr_t st_off = get_store_offset(st, phase);
3927 if (st_off < 0)
3928 break; // unknown junk in the inits
3929 if (st->in(MemNode::Memory) != zmem)
3930 break; // complicated store chains somehow in list
3931
3932 int st_size = st->as_Store()->memory_size();
3933 intptr_t next_init_off = st_off + st_size;
3934
3935 if (do_zeroing && zeroes_done < next_init_off) {
3936 // See if this store needs a zero before it or under it.
3937 intptr_t zeroes_needed = st_off;
3938
3939 if (st_size < BytesPerInt) {
3940 // Look for subword stores which only partially initialize words.
3941 // If we find some, we must lay down some word-level zeroes first,
3942 // underneath the subword stores.
3943 //
3944 // Examples:
3945 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
3946 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
3947 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
3948 //
3949 // Note: coalesce_subword_stores may have already done this,
3950 // if it was prompted by constant non-zero subword initializers.
3951 // But this case can still arise with non-constant stores.
3952
3953 intptr_t next_full_store = find_next_fullword_store(i, phase);
3954
3955 // In the examples above:
3956 // in(i) p q r s x y z
3957 // st_off 12 13 14 15 12 13 14
3958 // st_size 1 1 1 1 1 1 1
3959 // next_full_s. 12 16 16 16 16 16 16
3960 // z's_done 12 16 16 16 12 16 12
3961 // z's_needed 12 16 16 16 16 16 16
3962 // zsize 0 0 0 0 4 0 4
3963 if (next_full_store < 0) {
3964 // Conservative tack: Zero to end of current word.
3965 zeroes_needed = align_size_up(zeroes_needed, BytesPerInt);
3966 } else {
3967 // Zero to beginning of next fully initialized word.
3968 // Or, don't zero at all, if we are already in that word.
3969 assert(next_full_store >= zeroes_needed, "must go forward");
3970 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
3971 zeroes_needed = next_full_store;
3972 }
3973 }
3974
3975 if (zeroes_needed > zeroes_done) {
3976 intptr_t zsize = zeroes_needed - zeroes_done;
3977 // Do some incremental zeroing on rawmem, in parallel with inits.
3978 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3979 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3980 zeroes_done, zeroes_needed,
3981 phase);
3982 zeroes_done = zeroes_needed;
3983 if (zsize > Matcher::init_array_short_size && ++big_init_gaps > 2)
3984 do_zeroing = false; // leave the hole, next time
3985 }
3986 }
3987
3988 // Collect the store and move on:
3989 st->set_req(MemNode::Memory, inits);
3990 inits = st; // put it on the linearized chain
3991 set_req(i, zmem); // unhook from previous position
3992
3993 if (zeroes_done == st_off)
3994 zeroes_done = next_init_off;
3995
3996 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
3997
3998 #ifdef ASSERT
3999 // Various order invariants. Weaker than stores_are_sane because
4000 // a large constant tile can be filled in by smaller non-constant stores.
4001 assert(st_off >= last_init_off, "inits do not reverse");
4002 last_init_off = st_off;
4003 const Type* val = NULL;
4004 if (st_size >= BytesPerInt &&
4005 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
4006 (int)val->basic_type() < (int)T_OBJECT) {
4007 assert(st_off >= last_tile_end, "tiles do not overlap");
4008 assert(st_off >= last_init_end, "tiles do not overwrite inits");
4009 last_tile_end = MAX2(last_tile_end, next_init_off);
4010 } else {
4011 intptr_t st_tile_end = align_size_up(next_init_off, BytesPerLong);
4012 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
4013 assert(st_off >= last_init_end, "inits do not overlap");
4014 last_init_end = next_init_off; // it's a non-tile
4015 }
4016 #endif //ASSERT
4017 }
4018
4019 remove_extra_zeroes(); // clear out all the zmems left over
4020 add_req(inits);
4021
4022 if (!ZeroTLAB) {
4023 // If anything remains to be zeroed, zero it all now.
4024 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
4025 // if it is the last unused 4 bytes of an instance, forget about it
4026 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
4027 if (zeroes_done + BytesPerLong >= size_limit) {
4028 assert(allocation() != NULL, "");
4029 if (allocation()->Opcode() == Op_Allocate) {
4030 Node* klass_node = allocation()->in(AllocateNode::KlassNode);
4031 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass();
4032 if (zeroes_done == k->layout_helper())
4033 zeroes_done = size_limit;
4034 }
4035 }
4036 if (zeroes_done < size_limit) {
4037 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
4038 zeroes_done, size_in_bytes, phase);
4039 }
4040 }
4041
4042 set_complete(phase);
4043 return rawmem;
4044 }
4045
4046
4047 #ifdef ASSERT
4048 bool InitializeNode::stores_are_sane(PhaseTransform* phase) {
4049 if (is_complete())
4050 return true; // stores could be anything at this point
4051 assert(allocation() != NULL, "must be present");
4052 intptr_t last_off = allocation()->minimum_header_size();
4053 for (uint i = InitializeNode::RawStores; i < req(); i++) {
4054 Node* st = in(i);
4055 intptr_t st_off = get_store_offset(st, phase);
4056 if (st_off < 0) continue; // ignore dead garbage
4057 if (last_off > st_off) {
4058 tty->print_cr("*** bad store offset at %d: " INTX_FORMAT " > " INTX_FORMAT, i, last_off, st_off);
4059 this->dump(2);
4060 assert(false, "ascending store offsets");
4061 return false;
4062 }
4063 last_off = st_off + st->as_Store()->memory_size();
4064 }
4065 return true;
4066 }
4067 #endif //ASSERT
4068
4069
4070
4071
4072 //============================MergeMemNode=====================================
4073 //
4074 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
4075 // contributing store or call operations. Each contributor provides the memory
4076 // state for a particular "alias type" (see Compile::alias_type). For example,
4077 // if a MergeMem has an input X for alias category #6, then any memory reference
4078 // to alias category #6 may use X as its memory state input, as an exact equivalent
4079 // to using the MergeMem as a whole.
4080 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
4081 //
4082 // (Here, the <N> notation gives the index of the relevant adr_type.)
4083 //
4084 // In one special case (and more cases in the future), alias categories overlap.
4085 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
4086 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
4087 // it is exactly equivalent to that state W:
4088 // MergeMem(<Bot>: W) <==> W
4089 //
4090 // Usually, the merge has more than one input. In that case, where inputs
4091 // overlap (i.e., one is Bot), the narrower alias type determines the memory
4092 // state for that type, and the wider alias type (Bot) fills in everywhere else:
4093 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
4094 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
4095 //
4096 // A merge can take a "wide" memory state as one of its narrow inputs.
4097 // This simply means that the merge observes out only the relevant parts of
4098 // the wide input. That is, wide memory states arriving at narrow merge inputs
4099 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
4100 //
4101 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
4102 // and that memory slices "leak through":
4103 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
4104 //
4105 // But, in such a cascade, repeated memory slices can "block the leak":
4106 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
4107 //
4108 // In the last example, Y is not part of the combined memory state of the
4109 // outermost MergeMem. The system must, of course, prevent unschedulable
4110 // memory states from arising, so you can be sure that the state Y is somehow
4111 // a precursor to state Y'.
4112 //
4113 //
4114 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
4115 // of each MergeMemNode array are exactly the numerical alias indexes, including
4116 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
4117 // Compile::alias_type (and kin) produce and manage these indexes.
4118 //
4119 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
4120 // (Note that this provides quick access to the top node inside MergeMem methods,
4121 // without the need to reach out via TLS to Compile::current.)
4122 //
4123 // As a consequence of what was just described, a MergeMem that represents a full
4124 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
4125 // containing all alias categories.
4126 //
4127 // MergeMem nodes never (?) have control inputs, so in(0) is NULL.
4128 //
4129 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
4130 // a memory state for the alias type <N>, or else the top node, meaning that
4131 // there is no particular input for that alias type. Note that the length of
4132 // a MergeMem is variable, and may be extended at any time to accommodate new
4133 // memory states at larger alias indexes. When merges grow, they are of course
4134 // filled with "top" in the unused in() positions.
4135 //
4136 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
4137 // (Top was chosen because it works smoothly with passes like GCM.)
4138 //
4139 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
4140 // the type of random VM bits like TLS references.) Since it is always the
4141 // first non-Bot memory slice, some low-level loops use it to initialize an
4142 // index variable: for (i = AliasIdxRaw; i < req(); i++).
4143 //
4144 //
4145 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
4146 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
4147 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
4148 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
4149 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
4150 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
4151 //
4152 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
4153 // really that different from the other memory inputs. An abbreviation called
4154 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
4155 //
4156 //
4157 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
4158 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
4159 // that "emerges though" the base memory will be marked as excluding the alias types
4160 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
4161 //
4162 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
4163 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
4164 //
4165 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
4166 // (It is currently unimplemented.) As you can see, the resulting merge is
4167 // actually a disjoint union of memory states, rather than an overlay.
4168 //
4169
4170 //------------------------------MergeMemNode-----------------------------------
4171 Node* MergeMemNode::make_empty_memory() {
4172 Node* empty_memory = (Node*) Compile::current()->top();
4173 assert(empty_memory->is_top(), "correct sentinel identity");
4174 return empty_memory;
4175 }
4176
4177 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
4178 init_class_id(Class_MergeMem);
4179 // all inputs are nullified in Node::Node(int)
4180 // set_input(0, NULL); // no control input
4181
4182 // Initialize the edges uniformly to top, for starters.
4183 Node* empty_mem = make_empty_memory();
4184 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
4185 init_req(i,empty_mem);
4186 }
4187 assert(empty_memory() == empty_mem, "");
4188
4189 if( new_base != NULL && new_base->is_MergeMem() ) {
4190 MergeMemNode* mdef = new_base->as_MergeMem();
4191 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
4192 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
4193 mms.set_memory(mms.memory2());
4194 }
4195 assert(base_memory() == mdef->base_memory(), "");
4196 } else {
4197 set_base_memory(new_base);
4198 }
4199 }
4200
4201 // Make a new, untransformed MergeMem with the same base as 'mem'.
4202 // If mem is itself a MergeMem, populate the result with the same edges.
4203 MergeMemNode* MergeMemNode::make(Compile* C, Node* mem) {
4204 return new(C) MergeMemNode(mem);
4205 }
4206
4207 //------------------------------cmp--------------------------------------------
4208 uint MergeMemNode::hash() const { return NO_HASH; }
4209 uint MergeMemNode::cmp( const Node &n ) const {
4210 return (&n == this); // Always fail except on self
4211 }
4212
4213 //------------------------------Identity---------------------------------------
4214 Node* MergeMemNode::Identity(PhaseTransform *phase) {
4215 // Identity if this merge point does not record any interesting memory
4216 // disambiguations.
4217 Node* base_mem = base_memory();
4218 Node* empty_mem = empty_memory();
4219 if (base_mem != empty_mem) { // Memory path is not dead?
4220 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4221 Node* mem = in(i);
4222 if (mem != empty_mem && mem != base_mem) {
4223 return this; // Many memory splits; no change
4224 }
4225 }
4226 }
4227 return base_mem; // No memory splits; ID on the one true input
4228 }
4229
4230 //------------------------------Ideal------------------------------------------
4231 // This method is invoked recursively on chains of MergeMem nodes
4232 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4233 // Remove chain'd MergeMems
4234 //
4235 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
4236 // relative to the "in(Bot)". Since we are patching both at the same time,
4237 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
4238 // but rewrite each "in(i)" relative to the new "in(Bot)".
4239 Node *progress = NULL;
4240
4241
4242 Node* old_base = base_memory();
4243 Node* empty_mem = empty_memory();
4244 if (old_base == empty_mem)
4245 return NULL; // Dead memory path.
4246
4247 MergeMemNode* old_mbase;
4248 if (old_base != NULL && old_base->is_MergeMem())
4249 old_mbase = old_base->as_MergeMem();
4250 else
4251 old_mbase = NULL;
4252 Node* new_base = old_base;
4253
4254 // simplify stacked MergeMems in base memory
4255 if (old_mbase) new_base = old_mbase->base_memory();
4256
4257 // the base memory might contribute new slices beyond my req()
4258 if (old_mbase) grow_to_match(old_mbase);
4259
4260 // Look carefully at the base node if it is a phi.
4261 PhiNode* phi_base;
4262 if (new_base != NULL && new_base->is_Phi())
4263 phi_base = new_base->as_Phi();
4264 else
4265 phi_base = NULL;
4266
4267 Node* phi_reg = NULL;
4268 uint phi_len = (uint)-1;
4269 if (phi_base != NULL && !phi_base->is_copy()) {
4270 // do not examine phi if degraded to a copy
4271 phi_reg = phi_base->region();
4272 phi_len = phi_base->req();
4273 // see if the phi is unfinished
4274 for (uint i = 1; i < phi_len; i++) {
4275 if (phi_base->in(i) == NULL) {
4276 // incomplete phi; do not look at it yet!
4277 phi_reg = NULL;
4278 phi_len = (uint)-1;
4279 break;
4280 }
4281 }
4282 }
4283
4284 // Note: We do not call verify_sparse on entry, because inputs
4285 // can normalize to the base_memory via subsume_node or similar
4286 // mechanisms. This method repairs that damage.
4287
4288 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
4289
4290 // Look at each slice.
4291 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4292 Node* old_in = in(i);
4293 // calculate the old memory value
4294 Node* old_mem = old_in;
4295 if (old_mem == empty_mem) old_mem = old_base;
4296 assert(old_mem == memory_at(i), "");
4297
4298 // maybe update (reslice) the old memory value
4299
4300 // simplify stacked MergeMems
4301 Node* new_mem = old_mem;
4302 MergeMemNode* old_mmem;
4303 if (old_mem != NULL && old_mem->is_MergeMem())
4304 old_mmem = old_mem->as_MergeMem();
4305 else
4306 old_mmem = NULL;
4307 if (old_mmem == this) {
4308 // This can happen if loops break up and safepoints disappear.
4309 // A merge of BotPtr (default) with a RawPtr memory derived from a
4310 // safepoint can be rewritten to a merge of the same BotPtr with
4311 // the BotPtr phi coming into the loop. If that phi disappears
4312 // also, we can end up with a self-loop of the mergemem.
4313 // In general, if loops degenerate and memory effects disappear,
4314 // a mergemem can be left looking at itself. This simply means
4315 // that the mergemem's default should be used, since there is
4316 // no longer any apparent effect on this slice.
4317 // Note: If a memory slice is a MergeMem cycle, it is unreachable
4318 // from start. Update the input to TOP.
4319 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
4320 }
4321 else if (old_mmem != NULL) {
4322 new_mem = old_mmem->memory_at(i);
4323 }
4324 // else preceding memory was not a MergeMem
4325
4326 // replace equivalent phis (unfortunately, they do not GVN together)
4327 if (new_mem != NULL && new_mem != new_base &&
4328 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) {
4329 if (new_mem->is_Phi()) {
4330 PhiNode* phi_mem = new_mem->as_Phi();
4331 for (uint i = 1; i < phi_len; i++) {
4332 if (phi_base->in(i) != phi_mem->in(i)) {
4333 phi_mem = NULL;
4334 break;
4335 }
4336 }
4337 if (phi_mem != NULL) {
4338 // equivalent phi nodes; revert to the def
4339 new_mem = new_base;
4340 }
4341 }
4342 }
4343
4344 // maybe store down a new value
4345 Node* new_in = new_mem;
4346 if (new_in == new_base) new_in = empty_mem;
4347
4348 if (new_in != old_in) {
4349 // Warning: Do not combine this "if" with the previous "if"
4350 // A memory slice might have be be rewritten even if it is semantically
4351 // unchanged, if the base_memory value has changed.
4352 set_req(i, new_in);
4353 progress = this; // Report progress
4354 }
4355 }
4356
4357 if (new_base != old_base) {
4358 set_req(Compile::AliasIdxBot, new_base);
4359 // Don't use set_base_memory(new_base), because we need to update du.
4360 assert(base_memory() == new_base, "");
4361 progress = this;
4362 }
4363
4364 if( base_memory() == this ) {
4365 // a self cycle indicates this memory path is dead
4366 set_req(Compile::AliasIdxBot, empty_mem);
4367 }
4368
4369 // Resolve external cycles by calling Ideal on a MergeMem base_memory
4370 // Recursion must occur after the self cycle check above
4371 if( base_memory()->is_MergeMem() ) {
4372 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
4373 Node *m = phase->transform(new_mbase); // Rollup any cycles
4374 if( m != NULL && (m->is_top() ||
4375 m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem) ) {
4376 // propagate rollup of dead cycle to self
4377 set_req(Compile::AliasIdxBot, empty_mem);
4378 }
4379 }
4380
4381 if( base_memory() == empty_mem ) {
4382 progress = this;
4383 // Cut inputs during Parse phase only.
4384 // During Optimize phase a dead MergeMem node will be subsumed by Top.
4385 if( !can_reshape ) {
4386 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4387 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
4388 }
4389 }
4390 }
4391
4392 if( !progress && base_memory()->is_Phi() && can_reshape ) {
4393 // Check if PhiNode::Ideal's "Split phis through memory merges"
4394 // transform should be attempted. Look for this->phi->this cycle.
4395 uint merge_width = req();
4396 if (merge_width > Compile::AliasIdxRaw) {
4397 PhiNode* phi = base_memory()->as_Phi();
4398 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
4399 if (phi->in(i) == this) {
4400 phase->is_IterGVN()->_worklist.push(phi);
4401 break;
4402 }
4403 }
4404 }
4405 }
4406
4407 assert(progress || verify_sparse(), "please, no dups of base");
4408 return progress;
4409 }
4410
4411 //-------------------------set_base_memory-------------------------------------
4412 void MergeMemNode::set_base_memory(Node *new_base) {
4413 Node* empty_mem = empty_memory();
4414 set_req(Compile::AliasIdxBot, new_base);
4415 assert(memory_at(req()) == new_base, "must set default memory");
4416 // Clear out other occurrences of new_base:
4417 if (new_base != empty_mem) {
4418 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4419 if (in(i) == new_base) set_req(i, empty_mem);
4420 }
4421 }
4422 }
4423
4424 //------------------------------out_RegMask------------------------------------
4425 const RegMask &MergeMemNode::out_RegMask() const {
4426 return RegMask::Empty;
4427 }
4428
4429 //------------------------------dump_spec--------------------------------------
4430 #ifndef PRODUCT
4431 void MergeMemNode::dump_spec(outputStream *st) const {
4432 st->print(" {");
4433 Node* base_mem = base_memory();
4434 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
4435 Node* mem = memory_at(i);
4436 if (mem == base_mem) { st->print(" -"); continue; }
4437 st->print( " N%d:", mem->_idx );
4438 Compile::current()->get_adr_type(i)->dump_on(st);
4439 }
4440 st->print(" }");
4441 }
4442 #endif // !PRODUCT
4443
4444
4445 #ifdef ASSERT
4446 static bool might_be_same(Node* a, Node* b) {
4447 if (a == b) return true;
4448 if (!(a->is_Phi() || b->is_Phi())) return false;
4449 // phis shift around during optimization
4450 return true; // pretty stupid...
4451 }
4452
4453 // verify a narrow slice (either incoming or outgoing)
4454 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
4455 if (!VerifyAliases) return; // don't bother to verify unless requested
4456 if (is_error_reported()) return; // muzzle asserts when debugging an error
4457 if (Node::in_dump()) return; // muzzle asserts when printing
4458 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
4459 assert(n != NULL, "");
4460 // Elide intervening MergeMem's
4461 while (n->is_MergeMem()) {
4462 n = n->as_MergeMem()->memory_at(alias_idx);
4463 }
4464 Compile* C = Compile::current();
4465 const TypePtr* n_adr_type = n->adr_type();
4466 if (n == m->empty_memory()) {
4467 // Implicit copy of base_memory()
4468 } else if (n_adr_type != TypePtr::BOTTOM) {
4469 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type");
4470 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
4471 } else {
4472 // A few places like make_runtime_call "know" that VM calls are narrow,
4473 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
4474 bool expected_wide_mem = false;
4475 if (n == m->base_memory()) {
4476 expected_wide_mem = true;
4477 } else if (alias_idx == Compile::AliasIdxRaw ||
4478 n == m->memory_at(Compile::AliasIdxRaw)) {
4479 expected_wide_mem = true;
4480 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
4481 // memory can "leak through" calls on channels that
4482 // are write-once. Allow this also.
4483 expected_wide_mem = true;
4484 }
4485 assert(expected_wide_mem, "expected narrow slice replacement");
4486 }
4487 }
4488 #else // !ASSERT
4489 #define verify_memory_slice(m,i,n) (void)(0) // PRODUCT version is no-op
4490 #endif
4491
4492
4493 //-----------------------------memory_at---------------------------------------
4494 Node* MergeMemNode::memory_at(uint alias_idx) const {
4495 assert(alias_idx >= Compile::AliasIdxRaw ||
4496 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0,
4497 "must avoid base_memory and AliasIdxTop");
4498
4499 // Otherwise, it is a narrow slice.
4500 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
4501 Compile *C = Compile::current();
4502 if (is_empty_memory(n)) {
4503 // the array is sparse; empty slots are the "top" node
4504 n = base_memory();
4505 assert(Node::in_dump()
4506 || n == NULL || n->bottom_type() == Type::TOP
4507 || n->adr_type() == NULL // address is TOP
4508 || n->adr_type() == TypePtr::BOTTOM
4509 || n->adr_type() == TypeRawPtr::BOTTOM
4510 || Compile::current()->AliasLevel() == 0,
4511 "must be a wide memory");
4512 // AliasLevel == 0 if we are organizing the memory states manually.
4513 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
4514 } else {
4515 // make sure the stored slice is sane
4516 #ifdef ASSERT
4517 if (is_error_reported() || Node::in_dump()) {
4518 } else if (might_be_same(n, base_memory())) {
4519 // Give it a pass: It is a mostly harmless repetition of the base.
4520 // This can arise normally from node subsumption during optimization.
4521 } else {
4522 verify_memory_slice(this, alias_idx, n);
4523 }
4524 #endif
4525 }
4526 return n;
4527 }
4528
4529 //---------------------------set_memory_at-------------------------------------
4530 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
4531 verify_memory_slice(this, alias_idx, n);
4532 Node* empty_mem = empty_memory();
4533 if (n == base_memory()) n = empty_mem; // collapse default
4534 uint need_req = alias_idx+1;
4535 if (req() < need_req) {
4536 if (n == empty_mem) return; // already the default, so do not grow me
4537 // grow the sparse array
4538 do {
4539 add_req(empty_mem);
4540 } while (req() < need_req);
4541 }
4542 set_req( alias_idx, n );
4543 }
4544
4545
4546
4547 //--------------------------iteration_setup------------------------------------
4548 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
4549 if (other != NULL) {
4550 grow_to_match(other);
4551 // invariant: the finite support of mm2 is within mm->req()
4552 #ifdef ASSERT
4553 for (uint i = req(); i < other->req(); i++) {
4554 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
4555 }
4556 #endif
4557 }
4558 // Replace spurious copies of base_memory by top.
4559 Node* base_mem = base_memory();
4560 if (base_mem != NULL && !base_mem->is_top()) {
4561 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
4562 if (in(i) == base_mem)
4563 set_req(i, empty_memory());
4564 }
4565 }
4566 }
4567
4568 //---------------------------grow_to_match-------------------------------------
4569 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
4570 Node* empty_mem = empty_memory();
4571 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
4572 // look for the finite support of the other memory
4573 for (uint i = other->req(); --i >= req(); ) {
4574 if (other->in(i) != empty_mem) {
4575 uint new_len = i+1;
4576 while (req() < new_len) add_req(empty_mem);
4577 break;
4578 }
4579 }
4580 }
4581
4582 //---------------------------verify_sparse-------------------------------------
4583 #ifndef PRODUCT
4584 bool MergeMemNode::verify_sparse() const {
4585 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
4586 Node* base_mem = base_memory();
4587 // The following can happen in degenerate cases, since empty==top.
4588 if (is_empty_memory(base_mem)) return true;
4589 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4590 assert(in(i) != NULL, "sane slice");
4591 if (in(i) == base_mem) return false; // should have been the sentinel value!
4592 }
4593 return true;
4594 }
4595
4596 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
4597 Node* n;
4598 n = mm->in(idx);
4599 if (mem == n) return true; // might be empty_memory()
4600 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
4601 if (mem == n) return true;
4602 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) {
4603 if (mem == n) return true;
4604 if (n == NULL) break;
4605 }
4606 return false;
4607 }
4608 #endif // !PRODUCT