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