1 /*
2 * Copyright (c) 1997, 2016, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/systemDictionary.hpp"
27 #include "compiler/compileLog.hpp"
28 #include "memory/allocation.inline.hpp"
29 #include "memory/resourceArea.hpp"
30 #include "oops/objArrayKlass.hpp"
31 #include "opto/addnode.hpp"
32 #include "opto/arraycopynode.hpp"
33 #include "opto/cfgnode.hpp"
34 #include "opto/compile.hpp"
35 #include "opto/connode.hpp"
36 #include "opto/convertnode.hpp"
37 #include "opto/loopnode.hpp"
38 #include "opto/machnode.hpp"
39 #include "opto/matcher.hpp"
40 #include "opto/memnode.hpp"
41 #include "opto/mulnode.hpp"
42 #include "opto/narrowptrnode.hpp"
43 #include "opto/phaseX.hpp"
44 #include "opto/regmask.hpp"
45 #include "utilities/copy.hpp"
46
47 // Portions of code courtesy of Clifford Click
48
49 // Optimization - Graph Style
50
51 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st);
52
53 //=============================================================================
54 uint MemNode::size_of() const { return sizeof(*this); }
55
56 const TypePtr *MemNode::adr_type() const {
57 Node* adr = in(Address);
58 if (adr == NULL) return NULL; // node is dead
59 const TypePtr* cross_check = NULL;
60 DEBUG_ONLY(cross_check = _adr_type);
61 return calculate_adr_type(adr->bottom_type(), cross_check);
62 }
63
64 bool MemNode::check_if_adr_maybe_raw(Node* adr) {
65 if (adr != NULL) {
66 if (adr->bottom_type()->base() == Type::RawPtr || adr->bottom_type()->base() == Type::AnyPtr) {
67 return true;
68 }
69 }
70 return false;
71 }
72
73 #ifndef PRODUCT
74 void MemNode::dump_spec(outputStream *st) const {
75 if (in(Address) == NULL) return; // node is dead
76 #ifndef ASSERT
77 // fake the missing field
78 const TypePtr* _adr_type = NULL;
79 if (in(Address) != NULL)
80 _adr_type = in(Address)->bottom_type()->isa_ptr();
81 #endif
82 dump_adr_type(this, _adr_type, st);
83
84 Compile* C = Compile::current();
85 if (C->alias_type(_adr_type)->is_volatile()) {
86 st->print(" Volatile!");
87 }
88 if (_unaligned_access) {
89 st->print(" unaligned");
90 }
91 if (_mismatched_access) {
92 st->print(" mismatched");
93 }
94 }
95
96 void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) {
97 st->print(" @");
98 if (adr_type == NULL) {
99 st->print("NULL");
100 } else {
101 adr_type->dump_on(st);
102 Compile* C = Compile::current();
103 Compile::AliasType* atp = NULL;
104 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type);
105 if (atp == NULL)
106 st->print(", idx=?\?;");
107 else if (atp->index() == Compile::AliasIdxBot)
108 st->print(", idx=Bot;");
109 else if (atp->index() == Compile::AliasIdxTop)
110 st->print(", idx=Top;");
111 else if (atp->index() == Compile::AliasIdxRaw)
112 st->print(", idx=Raw;");
113 else {
114 ciField* field = atp->field();
115 if (field) {
116 st->print(", name=");
117 field->print_name_on(st);
118 }
119 st->print(", idx=%d;", atp->index());
120 }
121 }
122 }
123
124 extern void print_alias_types();
125
126 #endif
127
128 Node *MemNode::optimize_simple_memory_chain(Node *mchain, const TypeOopPtr *t_oop, Node *load, PhaseGVN *phase) {
129 assert((t_oop != NULL), "sanity");
130 bool is_instance = t_oop->is_known_instance_field();
131 bool is_boxed_value_load = t_oop->is_ptr_to_boxed_value() &&
132 (load != NULL) && load->is_Load() &&
133 (phase->is_IterGVN() != NULL);
134 if (!(is_instance || is_boxed_value_load))
135 return mchain; // don't try to optimize non-instance types
136 uint instance_id = t_oop->instance_id();
137 Node *start_mem = phase->C->start()->proj_out(TypeFunc::Memory);
138 Node *prev = NULL;
139 Node *result = mchain;
140 while (prev != result) {
141 prev = result;
142 if (result == start_mem)
143 break; // hit one of our sentinels
144 // skip over a call which does not affect this memory slice
145 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {
146 Node *proj_in = result->in(0);
147 if (proj_in->is_Allocate() && proj_in->_idx == instance_id) {
148 break; // hit one of our sentinels
149 } else if (proj_in->is_Call()) {
150 // ArrayCopyNodes processed here as well
151 CallNode *call = proj_in->as_Call();
152 if (!call->may_modify(t_oop, phase)) { // returns false for instances
153 result = call->in(TypeFunc::Memory);
154 }
155 } else if (proj_in->is_Initialize()) {
156 AllocateNode* alloc = proj_in->as_Initialize()->allocation();
157 // Stop if this is the initialization for the object instance which
158 // contains this memory slice, otherwise skip over it.
159 if ((alloc == NULL) || (alloc->_idx == instance_id)) {
160 break;
161 }
162 if (is_instance) {
163 result = proj_in->in(TypeFunc::Memory);
164 } else if (is_boxed_value_load) {
165 Node* klass = alloc->in(AllocateNode::KlassNode);
166 const TypeKlassPtr* tklass = phase->type(klass)->is_klassptr();
167 if (tklass->klass_is_exact() && !tklass->klass()->equals(t_oop->klass())) {
168 result = proj_in->in(TypeFunc::Memory); // not related allocation
169 }
170 }
171 } else if (proj_in->is_MemBar()) {
172 ArrayCopyNode* ac = NULL;
173 if (ArrayCopyNode::may_modify(t_oop, proj_in->as_MemBar(), phase, ac)) {
174 break;
175 }
176 result = proj_in->in(TypeFunc::Memory);
177 } else {
178 assert(false, "unexpected projection");
179 }
180 } else if (result->is_ClearArray()) {
181 if (!is_instance || !ClearArrayNode::step_through(&result, instance_id, phase)) {
182 // Can not bypass initialization of the instance
183 // we are looking for.
184 break;
185 }
186 // Otherwise skip it (the call updated 'result' value).
187 } else if (result->is_MergeMem()) {
188 result = step_through_mergemem(phase, result->as_MergeMem(), t_oop, NULL, tty);
189 }
190 }
191 return result;
192 }
193
194 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, Node *load, PhaseGVN *phase) {
195 const TypeOopPtr* t_oop = t_adr->isa_oopptr();
196 if (t_oop == NULL)
197 return mchain; // don't try to optimize non-oop types
198 Node* result = optimize_simple_memory_chain(mchain, t_oop, load, phase);
199 bool is_instance = t_oop->is_known_instance_field();
200 PhaseIterGVN *igvn = phase->is_IterGVN();
201 if (is_instance && igvn != NULL && result->is_Phi()) {
202 PhiNode *mphi = result->as_Phi();
203 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
204 const TypePtr *t = mphi->adr_type();
205 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
206 t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
207 t->is_oopptr()->cast_to_exactness(true)
208 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
209 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop) {
210 // clone the Phi with our address type
211 result = mphi->split_out_instance(t_adr, igvn);
212 } else {
213 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain");
214 }
215 }
216 return result;
217 }
218
219 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) {
220 uint alias_idx = phase->C->get_alias_index(tp);
221 Node *mem = mmem;
222 #ifdef ASSERT
223 {
224 // Check that current type is consistent with the alias index used during graph construction
225 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
226 bool consistent = adr_check == NULL || adr_check->empty() ||
227 phase->C->must_alias(adr_check, alias_idx );
228 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
229 if( !consistent && adr_check != NULL && !adr_check->empty() &&
230 tp->isa_aryptr() && tp->offset() == Type::OffsetBot &&
231 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot &&
232 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() ||
233 adr_check->offset() == oopDesc::klass_offset_in_bytes() ||
234 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) {
235 // don't assert if it is dead code.
236 consistent = true;
237 }
238 if( !consistent ) {
239 st->print("alias_idx==%d, adr_check==", alias_idx);
240 if( adr_check == NULL ) {
241 st->print("NULL");
242 } else {
243 adr_check->dump();
244 }
245 st->cr();
246 print_alias_types();
247 assert(consistent, "adr_check must match alias idx");
248 }
249 }
250 #endif
251 // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally
252 // means an array I have not precisely typed yet. Do not do any
253 // alias stuff with it any time soon.
254 const TypeOopPtr *toop = tp->isa_oopptr();
255 if( tp->base() != Type::AnyPtr &&
256 !(toop &&
257 toop->klass() != NULL &&
258 toop->klass()->is_java_lang_Object() &&
259 toop->offset() == Type::OffsetBot) ) {
260 // compress paths and change unreachable cycles to TOP
261 // If not, we can update the input infinitely along a MergeMem cycle
262 // Equivalent code in PhiNode::Ideal
263 Node* m = phase->transform(mmem);
264 // If transformed to a MergeMem, get the desired slice
265 // Otherwise the returned node represents memory for every slice
266 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
267 // Update input if it is progress over what we have now
268 }
269 return mem;
270 }
271
272 //--------------------------Ideal_common---------------------------------------
273 // Look for degenerate control and memory inputs. Bypass MergeMem inputs.
274 // Unhook non-raw memories from complete (macro-expanded) initializations.
275 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
276 // If our control input is a dead region, kill all below the region
277 Node *ctl = in(MemNode::Control);
278 if (ctl && remove_dead_region(phase, can_reshape))
279 return this;
280 ctl = in(MemNode::Control);
281 // Don't bother trying to transform a dead node
282 if (ctl && ctl->is_top()) return NodeSentinel;
283
284 PhaseIterGVN *igvn = phase->is_IterGVN();
285 // Wait if control on the worklist.
286 if (ctl && can_reshape && igvn != NULL) {
287 Node* bol = NULL;
288 Node* cmp = NULL;
289 if (ctl->in(0)->is_If()) {
290 assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity");
291 bol = ctl->in(0)->in(1);
292 if (bol->is_Bool())
293 cmp = ctl->in(0)->in(1)->in(1);
294 }
295 if (igvn->_worklist.member(ctl) ||
296 (bol != NULL && igvn->_worklist.member(bol)) ||
297 (cmp != NULL && igvn->_worklist.member(cmp)) ) {
298 // This control path may be dead.
299 // Delay this memory node transformation until the control is processed.
300 phase->is_IterGVN()->_worklist.push(this);
301 return NodeSentinel; // caller will return NULL
302 }
303 }
304 // Ignore if memory is dead, or self-loop
305 Node *mem = in(MemNode::Memory);
306 if (phase->type( mem ) == Type::TOP) return NodeSentinel; // caller will return NULL
307 assert(mem != this, "dead loop in MemNode::Ideal");
308
309 if (can_reshape && igvn != NULL && igvn->_worklist.member(mem)) {
310 // This memory slice may be dead.
311 // Delay this mem node transformation until the memory is processed.
312 phase->is_IterGVN()->_worklist.push(this);
313 return NodeSentinel; // caller will return NULL
314 }
315
316 Node *address = in(MemNode::Address);
317 const Type *t_adr = phase->type(address);
318 if (t_adr == Type::TOP) return NodeSentinel; // caller will return NULL
319
320 if (can_reshape && igvn != NULL &&
321 (igvn->_worklist.member(address) ||
322 igvn->_worklist.size() > 0 && (t_adr != adr_type())) ) {
323 // The address's base and type may change when the address is processed.
324 // Delay this mem node transformation until the address is processed.
325 phase->is_IterGVN()->_worklist.push(this);
326 return NodeSentinel; // caller will return NULL
327 }
328
329 // Do NOT remove or optimize the next lines: ensure a new alias index
330 // is allocated for an oop pointer type before Escape Analysis.
331 // Note: C++ will not remove it since the call has side effect.
332 if (t_adr->isa_oopptr()) {
333 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr());
334 }
335
336 Node* base = NULL;
337 if (address->is_AddP()) {
338 base = address->in(AddPNode::Base);
339 }
340 if (base != NULL && phase->type(base)->higher_equal(TypePtr::NULL_PTR) &&
341 !t_adr->isa_rawptr()) {
342 // Note: raw address has TOP base and top->higher_equal(TypePtr::NULL_PTR) is true.
343 // Skip this node optimization if its address has TOP base.
344 return NodeSentinel; // caller will return NULL
345 }
346
347 // Avoid independent memory operations
348 Node* old_mem = mem;
349
350 // The code which unhooks non-raw memories from complete (macro-expanded)
351 // initializations was removed. After macro-expansion all stores catched
352 // by Initialize node became raw stores and there is no information
353 // which memory slices they modify. So it is unsafe to move any memory
354 // operation above these stores. Also in most cases hooked non-raw memories
355 // were already unhooked by using information from detect_ptr_independence()
356 // and find_previous_store().
357
358 if (mem->is_MergeMem()) {
359 MergeMemNode* mmem = mem->as_MergeMem();
360 const TypePtr *tp = t_adr->is_ptr();
361
362 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
363 }
364
365 if (mem != old_mem) {
366 set_req(MemNode::Memory, mem);
367 if (can_reshape && old_mem->outcnt() == 0) {
368 igvn->_worklist.push(old_mem);
369 }
370 if (phase->type( mem ) == Type::TOP) return NodeSentinel;
371 return this;
372 }
373
374 // let the subclass continue analyzing...
375 return NULL;
376 }
377
378 // Helper function for proving some simple control dominations.
379 // Attempt to prove that all control inputs of 'dom' dominate 'sub'.
380 // Already assumes that 'dom' is available at 'sub', and that 'sub'
381 // is not a constant (dominated by the method's StartNode).
382 // Used by MemNode::find_previous_store to prove that the
383 // control input of a memory operation predates (dominates)
384 // an allocation it wants to look past.
385 bool MemNode::all_controls_dominate(Node* dom, Node* sub) {
386 if (dom == NULL || dom->is_top() || sub == NULL || sub->is_top())
387 return false; // Conservative answer for dead code
388
389 // Check 'dom'. Skip Proj and CatchProj nodes.
390 dom = dom->find_exact_control(dom);
391 if (dom == NULL || dom->is_top())
392 return false; // Conservative answer for dead code
393
394 if (dom == sub) {
395 // For the case when, for example, 'sub' is Initialize and the original
396 // 'dom' is Proj node of the 'sub'.
397 return false;
398 }
399
400 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub)
401 return true;
402
403 // 'dom' dominates 'sub' if its control edge and control edges
404 // of all its inputs dominate or equal to sub's control edge.
405
406 // Currently 'sub' is either Allocate, Initialize or Start nodes.
407 // Or Region for the check in LoadNode::Ideal();
408 // 'sub' should have sub->in(0) != NULL.
409 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() ||
410 sub->is_Region() || sub->is_Call(), "expecting only these nodes");
411
412 // Get control edge of 'sub'.
413 Node* orig_sub = sub;
414 sub = sub->find_exact_control(sub->in(0));
415 if (sub == NULL || sub->is_top())
416 return false; // Conservative answer for dead code
417
418 assert(sub->is_CFG(), "expecting control");
419
420 if (sub == dom)
421 return true;
422
423 if (sub->is_Start() || sub->is_Root())
424 return false;
425
426 {
427 // Check all control edges of 'dom'.
428
429 ResourceMark rm;
430 Arena* arena = Thread::current()->resource_area();
431 Node_List nlist(arena);
432 Unique_Node_List dom_list(arena);
433
434 dom_list.push(dom);
435 bool only_dominating_controls = false;
436
437 for (uint next = 0; next < dom_list.size(); next++) {
438 Node* n = dom_list.at(next);
439 if (n == orig_sub)
440 return false; // One of dom's inputs dominated by sub.
441 if (!n->is_CFG() && n->pinned()) {
442 // Check only own control edge for pinned non-control nodes.
443 n = n->find_exact_control(n->in(0));
444 if (n == NULL || n->is_top())
445 return false; // Conservative answer for dead code
446 assert(n->is_CFG(), "expecting control");
447 dom_list.push(n);
448 } else if (n->is_Con() || n->is_Start() || n->is_Root()) {
449 only_dominating_controls = true;
450 } else if (n->is_CFG()) {
451 if (n->dominates(sub, nlist))
452 only_dominating_controls = true;
453 else
454 return false;
455 } else {
456 // First, own control edge.
457 Node* m = n->find_exact_control(n->in(0));
458 if (m != NULL) {
459 if (m->is_top())
460 return false; // Conservative answer for dead code
461 dom_list.push(m);
462 }
463 // Now, the rest of edges.
464 uint cnt = n->req();
465 for (uint i = 1; i < cnt; i++) {
466 m = n->find_exact_control(n->in(i));
467 if (m == NULL || m->is_top())
468 continue;
469 dom_list.push(m);
470 }
471 }
472 }
473 return only_dominating_controls;
474 }
475 }
476
477 //---------------------detect_ptr_independence---------------------------------
478 // Used by MemNode::find_previous_store to prove that two base
479 // pointers are never equal.
480 // The pointers are accompanied by their associated allocations,
481 // if any, which have been previously discovered by the caller.
482 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
483 Node* p2, AllocateNode* a2,
484 PhaseTransform* phase) {
485 // Attempt to prove that these two pointers cannot be aliased.
486 // They may both manifestly be allocations, and they should differ.
487 // Or, if they are not both allocations, they can be distinct constants.
488 // Otherwise, one is an allocation and the other a pre-existing value.
489 if (a1 == NULL && a2 == NULL) { // neither an allocation
490 return (p1 != p2) && p1->is_Con() && p2->is_Con();
491 } else if (a1 != NULL && a2 != NULL) { // both allocations
492 return (a1 != a2);
493 } else if (a1 != NULL) { // one allocation a1
494 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.)
495 return all_controls_dominate(p2, a1);
496 } else { //(a2 != NULL) // one allocation a2
497 return all_controls_dominate(p1, a2);
498 }
499 return false;
500 }
501
502
503 // Find an arraycopy that must have set (can_see_stored_value=true) or
504 // could have set (can_see_stored_value=false) the value for this load
505 Node* LoadNode::find_previous_arraycopy(PhaseTransform* phase, Node* ld_alloc, Node*& mem, bool can_see_stored_value) const {
506 if (mem->is_Proj() && mem->in(0) != NULL && (mem->in(0)->Opcode() == Op_MemBarStoreStore ||
507 mem->in(0)->Opcode() == Op_MemBarCPUOrder)) {
508 Node* mb = mem->in(0);
509 if (mb->in(0) != NULL && mb->in(0)->is_Proj() &&
510 mb->in(0)->in(0) != NULL && mb->in(0)->in(0)->is_ArrayCopy()) {
511 ArrayCopyNode* ac = mb->in(0)->in(0)->as_ArrayCopy();
512 if (ac->is_clonebasic()) {
513 intptr_t offset;
514 AllocateNode* alloc = AllocateNode::Ideal_allocation(ac->in(ArrayCopyNode::Dest), phase, offset);
515 assert(alloc != NULL && (!ReduceBulkZeroing || alloc->initialization()->is_complete_with_arraycopy()), "broken allocation");
516 if (alloc == ld_alloc) {
517 return ac;
518 }
519 }
520 }
521 } else if (mem->is_Proj() && mem->in(0) != NULL && mem->in(0)->is_ArrayCopy()) {
522 ArrayCopyNode* ac = mem->in(0)->as_ArrayCopy();
523
524 if (ac->is_arraycopy_validated() ||
525 ac->is_copyof_validated() ||
526 ac->is_copyofrange_validated()) {
527 Node* ld_addp = in(MemNode::Address);
528 if (ld_addp->is_AddP()) {
529 Node* ld_base = ld_addp->in(AddPNode::Address);
530 Node* ld_offs = ld_addp->in(AddPNode::Offset);
531
532 Node* dest = ac->in(ArrayCopyNode::Dest);
533
534 if (dest == ld_base) {
535 const TypeX *ld_offs_t = phase->type(ld_offs)->isa_intptr_t();
536 if (ac->modifies(ld_offs_t->_lo, ld_offs_t->_hi, phase, can_see_stored_value)) {
537 return ac;
538 }
539 if (!can_see_stored_value) {
540 mem = ac->in(TypeFunc::Memory);
541 }
542 }
543 }
544 }
545 }
546 return NULL;
547 }
548
549 // The logic for reordering loads and stores uses four steps:
550 // (a) Walk carefully past stores and initializations which we
551 // can prove are independent of this load.
552 // (b) Observe that the next memory state makes an exact match
553 // with self (load or store), and locate the relevant store.
554 // (c) Ensure that, if we were to wire self directly to the store,
555 // the optimizer would fold it up somehow.
556 // (d) Do the rewiring, and return, depending on some other part of
557 // the optimizer to fold up the load.
558 // This routine handles steps (a) and (b). Steps (c) and (d) are
559 // specific to loads and stores, so they are handled by the callers.
560 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.)
561 //
562 Node* MemNode::find_previous_store(PhaseTransform* phase) {
563 Node* ctrl = in(MemNode::Control);
564 Node* adr = in(MemNode::Address);
565 intptr_t offset = 0;
566 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
567 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase);
568
569 if (offset == Type::OffsetBot)
570 return NULL; // cannot unalias unless there are precise offsets
571
572 const bool adr_maybe_raw = check_if_adr_maybe_raw(adr);
573 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr();
574
575 intptr_t size_in_bytes = memory_size();
576
577 Node* mem = in(MemNode::Memory); // start searching here...
578
579 int cnt = 50; // Cycle limiter
580 for (;;) { // While we can dance past unrelated stores...
581 if (--cnt < 0) break; // Caught in cycle or a complicated dance?
582
583 Node* prev = mem;
584 if (mem->is_Store()) {
585 Node* st_adr = mem->in(MemNode::Address);
586 intptr_t st_offset = 0;
587 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
588 if (st_base == NULL)
589 break; // inscrutable pointer
590
591 // For raw accesses it's not enough to prove that constant offsets don't intersect.
592 // We need the bases to be the equal in order for the offset check to make sense.
593 if ((adr_maybe_raw || check_if_adr_maybe_raw(st_adr)) && st_base != base) {
594 break;
595 }
596
597 if (st_offset != offset && st_offset != Type::OffsetBot) {
598 const int MAX_STORE = BytesPerLong;
599 if (st_offset >= offset + size_in_bytes ||
600 st_offset <= offset - MAX_STORE ||
601 st_offset <= offset - mem->as_Store()->memory_size()) {
602 // Success: The offsets are provably independent.
603 // (You may ask, why not just test st_offset != offset and be done?
604 // The answer is that stores of different sizes can co-exist
605 // in the same sequence of RawMem effects. We sometimes initialize
606 // a whole 'tile' of array elements with a single jint or jlong.)
607 mem = mem->in(MemNode::Memory);
608 continue; // (a) advance through independent store memory
609 }
610 }
611 if (st_base != base &&
612 detect_ptr_independence(base, alloc,
613 st_base,
614 AllocateNode::Ideal_allocation(st_base, phase),
615 phase)) {
616 // Success: The bases are provably independent.
617 mem = mem->in(MemNode::Memory);
618 continue; // (a) advance through independent store memory
619 }
620
621 // (b) At this point, if the bases or offsets do not agree, we lose,
622 // since we have not managed to prove 'this' and 'mem' independent.
623 if (st_base == base && st_offset == offset) {
624 return mem; // let caller handle steps (c), (d)
625 }
626
627 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
628 InitializeNode* st_init = mem->in(0)->as_Initialize();
629 AllocateNode* st_alloc = st_init->allocation();
630 if (st_alloc == NULL)
631 break; // something degenerated
632 bool known_identical = false;
633 bool known_independent = false;
634 if (alloc == st_alloc)
635 known_identical = true;
636 else if (alloc != NULL)
637 known_independent = true;
638 else if (all_controls_dominate(this, st_alloc))
639 known_independent = true;
640
641 if (known_independent) {
642 // The bases are provably independent: Either they are
643 // manifestly distinct allocations, or else the control
644 // of this load dominates the store's allocation.
645 int alias_idx = phase->C->get_alias_index(adr_type());
646 if (alias_idx == Compile::AliasIdxRaw) {
647 mem = st_alloc->in(TypeFunc::Memory);
648 } else {
649 mem = st_init->memory(alias_idx);
650 }
651 continue; // (a) advance through independent store memory
652 }
653
654 // (b) at this point, if we are not looking at a store initializing
655 // the same allocation we are loading from, we lose.
656 if (known_identical) {
657 // From caller, can_see_stored_value will consult find_captured_store.
658 return mem; // let caller handle steps (c), (d)
659 }
660
661 } else if (find_previous_arraycopy(phase, alloc, mem, false) != NULL) {
662 if (prev != mem) {
663 // Found an arraycopy but it doesn't affect that load
664 continue;
665 }
666 // Found an arraycopy that may affect that load
667 return mem;
668 } else if (addr_t != NULL && addr_t->is_known_instance_field()) {
669 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
670 if (mem->is_Proj() && mem->in(0)->is_Call()) {
671 // ArrayCopyNodes processed here as well.
672 CallNode *call = mem->in(0)->as_Call();
673 if (!call->may_modify(addr_t, phase)) {
674 mem = call->in(TypeFunc::Memory);
675 continue; // (a) advance through independent call memory
676 }
677 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) {
678 ArrayCopyNode* ac = NULL;
679 if (ArrayCopyNode::may_modify(addr_t, mem->in(0)->as_MemBar(), phase, ac)) {
680 break;
681 }
682 mem = mem->in(0)->in(TypeFunc::Memory);
683 continue; // (a) advance through independent MemBar memory
684 } else if (mem->is_ClearArray()) {
685 if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) {
686 // (the call updated 'mem' value)
687 continue; // (a) advance through independent allocation memory
688 } else {
689 // Can not bypass initialization of the instance
690 // we are looking for.
691 return mem;
692 }
693 } else if (mem->is_MergeMem()) {
694 int alias_idx = phase->C->get_alias_index(adr_type());
695 mem = mem->as_MergeMem()->memory_at(alias_idx);
696 continue; // (a) advance through independent MergeMem memory
697 }
698 }
699
700 // Unless there is an explicit 'continue', we must bail out here,
701 // because 'mem' is an inscrutable memory state (e.g., a call).
702 break;
703 }
704
705 return NULL; // bail out
706 }
707
708 //----------------------calculate_adr_type-------------------------------------
709 // Helper function. Notices when the given type of address hits top or bottom.
710 // Also, asserts a cross-check of the type against the expected address type.
711 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
712 if (t == Type::TOP) return NULL; // does not touch memory any more?
713 #ifdef PRODUCT
714 cross_check = NULL;
715 #else
716 if (!VerifyAliases || is_error_reported() || Node::in_dump()) cross_check = NULL;
717 #endif
718 const TypePtr* tp = t->isa_ptr();
719 if (tp == NULL) {
720 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
721 return TypePtr::BOTTOM; // touches lots of memory
722 } else {
723 #ifdef ASSERT
724 // %%%% [phh] We don't check the alias index if cross_check is
725 // TypeRawPtr::BOTTOM. Needs to be investigated.
726 if (cross_check != NULL &&
727 cross_check != TypePtr::BOTTOM &&
728 cross_check != TypeRawPtr::BOTTOM) {
729 // Recheck the alias index, to see if it has changed (due to a bug).
730 Compile* C = Compile::current();
731 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
732 "must stay in the original alias category");
733 // The type of the address must be contained in the adr_type,
734 // disregarding "null"-ness.
735 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
736 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
737 assert(cross_check->meet(tp_notnull) == cross_check->remove_speculative(),
738 "real address must not escape from expected memory type");
739 }
740 #endif
741 return tp;
742 }
743 }
744
745 //=============================================================================
746 // Should LoadNode::Ideal() attempt to remove control edges?
747 bool LoadNode::can_remove_control() const {
748 return true;
749 }
750 uint LoadNode::size_of() const { return sizeof(*this); }
751 uint LoadNode::cmp( const Node &n ) const
752 { return !Type::cmp( _type, ((LoadNode&)n)._type ); }
753 const Type *LoadNode::bottom_type() const { return _type; }
754 uint LoadNode::ideal_reg() const {
755 return _type->ideal_reg();
756 }
757
758 #ifndef PRODUCT
759 void LoadNode::dump_spec(outputStream *st) const {
760 MemNode::dump_spec(st);
761 if( !Verbose && !WizardMode ) {
762 // standard dump does this in Verbose and WizardMode
763 st->print(" #"); _type->dump_on(st);
764 }
765 if (!depends_only_on_test()) {
766 st->print(" (does not depend only on test)");
767 }
768 }
769 #endif
770
771 #ifdef ASSERT
772 //----------------------------is_immutable_value-------------------------------
773 // Helper function to allow a raw load without control edge for some cases
774 bool LoadNode::is_immutable_value(Node* adr) {
775 return (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() &&
776 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal &&
777 (adr->in(AddPNode::Offset)->find_intptr_t_con(-1) ==
778 in_bytes(JavaThread::osthread_offset())));
779 }
780 #endif
781
782 //----------------------------LoadNode::make-----------------------------------
783 // Polymorphic factory method:
784 Node *LoadNode::make(PhaseGVN& gvn, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt, MemOrd mo,
785 ControlDependency control_dependency, bool unaligned, bool mismatched) {
786 Compile* C = gvn.C;
787
788 // sanity check the alias category against the created node type
789 assert(!(adr_type->isa_oopptr() &&
790 adr_type->offset() == oopDesc::klass_offset_in_bytes()),
791 "use LoadKlassNode instead");
792 assert(!(adr_type->isa_aryptr() &&
793 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
794 "use LoadRangeNode instead");
795 // Check control edge of raw loads
796 assert( ctl != NULL || C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
797 // oop will be recorded in oop map if load crosses safepoint
798 rt->isa_oopptr() || is_immutable_value(adr),
799 "raw memory operations should have control edge");
800 LoadNode* load = NULL;
801 switch (bt) {
802 case T_BOOLEAN: load = new LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
803 case T_BYTE: load = new LoadBNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
804 case T_INT: load = new LoadINode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
805 case T_CHAR: load = new LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
806 case T_SHORT: load = new LoadSNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
807 case T_LONG: load = new LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency); break;
808 case T_FLOAT: load = new LoadFNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); break;
809 case T_DOUBLE: load = new LoadDNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); break;
810 case T_ADDRESS: load = new LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency); break;
811 case T_VALUETYPE:
812 case T_OBJECT:
813 #ifdef _LP64
814 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
815 load = new LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo, control_dependency);
816 } else
817 #endif
818 {
819 assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop");
820 load = new LoadPNode(ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency);
821 }
822 break;
823 }
824 assert(load != NULL, "LoadNode should have been created");
825 if (unaligned) {
826 load->set_unaligned_access();
827 }
828 if (mismatched) {
829 load->set_mismatched_access();
830 }
831 if (load->Opcode() == Op_LoadN) {
832 Node* ld = gvn.transform(load);
833 return new DecodeNNode(ld, ld->bottom_type()->make_ptr());
834 }
835
836 return load;
837 }
838
839 LoadLNode* LoadLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo,
840 ControlDependency control_dependency, bool unaligned, bool mismatched) {
841 bool require_atomic = true;
842 LoadLNode* load = new LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency, require_atomic);
843 if (unaligned) {
844 load->set_unaligned_access();
845 }
846 if (mismatched) {
847 load->set_mismatched_access();
848 }
849 return load;
850 }
851
852 LoadDNode* LoadDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo,
853 ControlDependency control_dependency, bool unaligned, bool mismatched) {
854 bool require_atomic = true;
855 LoadDNode* load = new LoadDNode(ctl, mem, adr, adr_type, rt, mo, control_dependency, require_atomic);
856 if (unaligned) {
857 load->set_unaligned_access();
858 }
859 if (mismatched) {
860 load->set_mismatched_access();
861 }
862 return load;
863 }
864
865
866
867 //------------------------------hash-------------------------------------------
868 uint LoadNode::hash() const {
869 // unroll addition of interesting fields
870 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
871 }
872
873 static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) {
874 if ((atp != NULL) && (atp->index() >= Compile::AliasIdxRaw)) {
875 bool non_volatile = (atp->field() != NULL) && !atp->field()->is_volatile();
876 bool is_stable_ary = FoldStableValues &&
877 (tp != NULL) && (tp->isa_aryptr() != NULL) &&
878 tp->isa_aryptr()->is_stable();
879
880 return (eliminate_boxing && non_volatile) || is_stable_ary;
881 }
882
883 return false;
884 }
885
886 // Is the value loaded previously stored by an arraycopy? If so return
887 // a load node that reads from the source array so we may be able to
888 // optimize out the ArrayCopy node later.
889 Node* LoadNode::can_see_arraycopy_value(Node* st, PhaseTransform* phase) const {
890 Node* ld_adr = in(MemNode::Address);
891 intptr_t ld_off = 0;
892 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
893 Node* ac = find_previous_arraycopy(phase, ld_alloc, st, true);
894 if (ac != NULL) {
895 assert(ac->is_ArrayCopy(), "what kind of node can this be?");
896
897 Node* ld = clone();
898 if (ac->as_ArrayCopy()->is_clonebasic()) {
899 assert(ld_alloc != NULL, "need an alloc");
900 Node* addp = in(MemNode::Address)->clone();
901 assert(addp->is_AddP(), "address must be addp");
902 assert(addp->in(AddPNode::Base) == ac->in(ArrayCopyNode::Dest)->in(AddPNode::Base), "strange pattern");
903 assert(addp->in(AddPNode::Address) == ac->in(ArrayCopyNode::Dest)->in(AddPNode::Address), "strange pattern");
904 addp->set_req(AddPNode::Base, ac->in(ArrayCopyNode::Src)->in(AddPNode::Base));
905 addp->set_req(AddPNode::Address, ac->in(ArrayCopyNode::Src)->in(AddPNode::Address));
906 ld->set_req(MemNode::Address, phase->transform(addp));
907 if (in(0) != NULL) {
908 assert(ld_alloc->in(0) != NULL, "alloc must have control");
909 ld->set_req(0, ld_alloc->in(0));
910 }
911 } else {
912 Node* addp = in(MemNode::Address)->clone();
913 assert(addp->in(AddPNode::Base) == addp->in(AddPNode::Address), "should be");
914 addp->set_req(AddPNode::Base, ac->in(ArrayCopyNode::Src));
915 addp->set_req(AddPNode::Address, ac->in(ArrayCopyNode::Src));
916
917 const TypeAryPtr* ary_t = phase->type(in(MemNode::Address))->isa_aryptr();
918 BasicType ary_elem = ary_t->klass()->as_array_klass()->element_type()->basic_type();
919 uint header = arrayOopDesc::base_offset_in_bytes(ary_elem);
920 uint shift = exact_log2(type2aelembytes(ary_elem));
921
922 Node* diff = phase->transform(new SubINode(ac->in(ArrayCopyNode::SrcPos), ac->in(ArrayCopyNode::DestPos)));
923 #ifdef _LP64
924 diff = phase->transform(new ConvI2LNode(diff));
925 #endif
926 diff = phase->transform(new LShiftXNode(diff, phase->intcon(shift)));
927
928 Node* offset = phase->transform(new AddXNode(addp->in(AddPNode::Offset), diff));
929 addp->set_req(AddPNode::Offset, offset);
930 ld->set_req(MemNode::Address, phase->transform(addp));
931
932 if (in(0) != NULL) {
933 assert(ac->in(0) != NULL, "alloc must have control");
934 ld->set_req(0, ac->in(0));
935 }
936 }
937 // load depends on the tests that validate the arraycopy
938 ld->as_Load()->_control_dependency = Pinned;
939 return ld;
940 }
941 return NULL;
942 }
943
944
945 //---------------------------can_see_stored_value------------------------------
946 // This routine exists to make sure this set of tests is done the same
947 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
948 // will change the graph shape in a way which makes memory alive twice at the
949 // same time (uses the Oracle model of aliasing), then some
950 // LoadXNode::Identity will fold things back to the equivalence-class model
951 // of aliasing.
952 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const {
953 Node* ld_adr = in(MemNode::Address);
954 intptr_t ld_off = 0;
955 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
956 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
957 Compile::AliasType* atp = (tp != NULL) ? phase->C->alias_type(tp) : NULL;
958 // This is more general than load from boxing objects.
959 if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) {
960 uint alias_idx = atp->index();
961 bool final = !atp->is_rewritable();
962 Node* result = NULL;
963 Node* current = st;
964 // Skip through chains of MemBarNodes checking the MergeMems for
965 // new states for the slice of this load. Stop once any other
966 // kind of node is encountered. Loads from final memory can skip
967 // through any kind of MemBar but normal loads shouldn't skip
968 // through MemBarAcquire since the could allow them to move out of
969 // a synchronized region.
970 while (current->is_Proj()) {
971 int opc = current->in(0)->Opcode();
972 if ((final && (opc == Op_MemBarAcquire ||
973 opc == Op_MemBarAcquireLock ||
974 opc == Op_LoadFence)) ||
975 opc == Op_MemBarRelease ||
976 opc == Op_StoreFence ||
977 opc == Op_MemBarReleaseLock ||
978 opc == Op_MemBarStoreStore ||
979 opc == Op_MemBarCPUOrder) {
980 Node* mem = current->in(0)->in(TypeFunc::Memory);
981 if (mem->is_MergeMem()) {
982 MergeMemNode* merge = mem->as_MergeMem();
983 Node* new_st = merge->memory_at(alias_idx);
984 if (new_st == merge->base_memory()) {
985 // Keep searching
986 current = new_st;
987 continue;
988 }
989 // Save the new memory state for the slice and fall through
990 // to exit.
991 result = new_st;
992 }
993 }
994 break;
995 }
996 if (result != NULL) {
997 st = result;
998 }
999 }
1000
1001 // Loop around twice in the case Load -> Initialize -> Store.
1002 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
1003 for (int trip = 0; trip <= 1; trip++) {
1004
1005 if (st->is_Store()) {
1006 Node* st_adr = st->in(MemNode::Address);
1007 if (!phase->eqv(st_adr, ld_adr)) {
1008 // Try harder before giving up... Match raw and non-raw pointers.
1009 intptr_t st_off = 0;
1010 AllocateNode* alloc = AllocateNode::Ideal_allocation(st_adr, phase, st_off);
1011 if (alloc == NULL) return NULL;
1012 if (alloc != ld_alloc) return NULL;
1013 if (ld_off != st_off) return NULL;
1014 // At this point we have proven something like this setup:
1015 // A = Allocate(...)
1016 // L = LoadQ(, AddP(CastPP(, A.Parm),, #Off))
1017 // S = StoreQ(, AddP(, A.Parm , #Off), V)
1018 // (Actually, we haven't yet proven the Q's are the same.)
1019 // In other words, we are loading from a casted version of
1020 // the same pointer-and-offset that we stored to.
1021 // Thus, we are able to replace L by V.
1022 }
1023 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
1024 if (store_Opcode() != st->Opcode())
1025 return NULL;
1026 return st->in(MemNode::ValueIn);
1027 }
1028
1029 // A load from a freshly-created object always returns zero.
1030 // (This can happen after LoadNode::Ideal resets the load's memory input
1031 // to find_captured_store, which returned InitializeNode::zero_memory.)
1032 if (st->is_Proj() && st->in(0)->is_Allocate() &&
1033 (st->in(0) == ld_alloc) &&
1034 (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) {
1035 // return a zero value for the load's basic type
1036 // (This is one of the few places where a generic PhaseTransform
1037 // can create new nodes. Think of it as lazily manifesting
1038 // virtually pre-existing constants.)
1039 assert(memory_type() != T_VALUETYPE, "should not be used for value types");
1040 return phase->zerocon(memory_type());
1041 }
1042
1043 // A load from an initialization barrier can match a captured store.
1044 if (st->is_Proj() && st->in(0)->is_Initialize()) {
1045 InitializeNode* init = st->in(0)->as_Initialize();
1046 AllocateNode* alloc = init->allocation();
1047 if ((alloc != NULL) && (alloc == ld_alloc)) {
1048 // examine a captured store value
1049 st = init->find_captured_store(ld_off, memory_size(), phase);
1050 if (st != NULL) {
1051 continue; // take one more trip around
1052 }
1053 }
1054 }
1055
1056 // Load boxed value from result of valueOf() call is input parameter.
1057 if (this->is_Load() && ld_adr->is_AddP() &&
1058 (tp != NULL) && tp->is_ptr_to_boxed_value()) {
1059 intptr_t ignore = 0;
1060 Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore);
1061 if (base != NULL && base->is_Proj() &&
1062 base->as_Proj()->_con == TypeFunc::Parms &&
1063 base->in(0)->is_CallStaticJava() &&
1064 base->in(0)->as_CallStaticJava()->is_boxing_method()) {
1065 return base->in(0)->in(TypeFunc::Parms);
1066 }
1067 }
1068
1069 break;
1070 }
1071
1072 return NULL;
1073 }
1074
1075 //----------------------is_instance_field_load_with_local_phi------------------
1076 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
1077 if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl &&
1078 in(Address)->is_AddP() ) {
1079 const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr();
1080 // Only instances and boxed values.
1081 if( t_oop != NULL &&
1082 (t_oop->is_ptr_to_boxed_value() ||
1083 t_oop->is_known_instance_field()) &&
1084 t_oop->offset() != Type::OffsetBot &&
1085 t_oop->offset() != Type::OffsetTop) {
1086 return true;
1087 }
1088 }
1089 return false;
1090 }
1091
1092 //------------------------------Identity---------------------------------------
1093 // Loads are identity if previous store is to same address
1094 Node* LoadNode::Identity(PhaseGVN* phase) {
1095 // If the previous store-maker is the right kind of Store, and the store is
1096 // to the same address, then we are equal to the value stored.
1097 Node* mem = in(Memory);
1098 Node* value = can_see_stored_value(mem, phase);
1099 if( value ) {
1100 // byte, short & char stores truncate naturally.
1101 // A load has to load the truncated value which requires
1102 // some sort of masking operation and that requires an
1103 // Ideal call instead of an Identity call.
1104 if (memory_size() < BytesPerInt) {
1105 // If the input to the store does not fit with the load's result type,
1106 // it must be truncated via an Ideal call.
1107 if (!phase->type(value)->higher_equal(phase->type(this)))
1108 return this;
1109 }
1110 // (This works even when value is a Con, but LoadNode::Value
1111 // usually runs first, producing the singleton type of the Con.)
1112 return value;
1113 }
1114
1115 // Search for an existing data phi which was generated before for the same
1116 // instance's field to avoid infinite generation of phis in a loop.
1117 Node *region = mem->in(0);
1118 if (is_instance_field_load_with_local_phi(region)) {
1119 const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr();
1120 int this_index = phase->C->get_alias_index(addr_t);
1121 int this_offset = addr_t->offset();
1122 int this_iid = addr_t->instance_id();
1123 if (!addr_t->is_known_instance() &&
1124 addr_t->is_ptr_to_boxed_value()) {
1125 // Use _idx of address base (could be Phi node) for boxed values.
1126 intptr_t ignore = 0;
1127 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1128 this_iid = base->_idx;
1129 }
1130 const Type* this_type = bottom_type();
1131 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1132 Node* phi = region->fast_out(i);
1133 if (phi->is_Phi() && phi != mem &&
1134 phi->as_Phi()->is_same_inst_field(this_type, (int)mem->_idx, this_iid, this_index, this_offset)) {
1135 return phi;
1136 }
1137 }
1138 }
1139
1140 return this;
1141 }
1142
1143 // Construct an equivalent unsigned load.
1144 Node* LoadNode::convert_to_unsigned_load(PhaseGVN& gvn) {
1145 BasicType bt = T_ILLEGAL;
1146 const Type* rt = NULL;
1147 switch (Opcode()) {
1148 case Op_LoadUB: return this;
1149 case Op_LoadUS: return this;
1150 case Op_LoadB: bt = T_BOOLEAN; rt = TypeInt::UBYTE; break;
1151 case Op_LoadS: bt = T_CHAR; rt = TypeInt::CHAR; break;
1152 default:
1153 assert(false, "no unsigned variant: %s", Name());
1154 return NULL;
1155 }
1156 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1157 raw_adr_type(), rt, bt, _mo, _control_dependency,
1158 is_unaligned_access(), is_mismatched_access());
1159 }
1160
1161 // Construct an equivalent signed load.
1162 Node* LoadNode::convert_to_signed_load(PhaseGVN& gvn) {
1163 BasicType bt = T_ILLEGAL;
1164 const Type* rt = NULL;
1165 switch (Opcode()) {
1166 case Op_LoadUB: bt = T_BYTE; rt = TypeInt::BYTE; break;
1167 case Op_LoadUS: bt = T_SHORT; rt = TypeInt::SHORT; break;
1168 case Op_LoadB: // fall through
1169 case Op_LoadS: // fall through
1170 case Op_LoadI: // fall through
1171 case Op_LoadL: return this;
1172 default:
1173 assert(false, "no signed variant: %s", Name());
1174 return NULL;
1175 }
1176 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1177 raw_adr_type(), rt, bt, _mo, _control_dependency,
1178 is_unaligned_access(), is_mismatched_access());
1179 }
1180
1181 // We're loading from an object which has autobox behaviour.
1182 // If this object is result of a valueOf call we'll have a phi
1183 // merging a newly allocated object and a load from the cache.
1184 // We want to replace this load with the original incoming
1185 // argument to the valueOf call.
1186 Node* LoadNode::eliminate_autobox(PhaseGVN* phase) {
1187 assert(phase->C->eliminate_boxing(), "sanity");
1188 intptr_t ignore = 0;
1189 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1190 if ((base == NULL) || base->is_Phi()) {
1191 // Push the loads from the phi that comes from valueOf up
1192 // through it to allow elimination of the loads and the recovery
1193 // of the original value. It is done in split_through_phi().
1194 return NULL;
1195 } else if (base->is_Load() ||
1196 base->is_DecodeN() && base->in(1)->is_Load()) {
1197 // Eliminate the load of boxed value for integer types from the cache
1198 // array by deriving the value from the index into the array.
1199 // Capture the offset of the load and then reverse the computation.
1200
1201 // Get LoadN node which loads a boxing object from 'cache' array.
1202 if (base->is_DecodeN()) {
1203 base = base->in(1);
1204 }
1205 if (!base->in(Address)->is_AddP()) {
1206 return NULL; // Complex address
1207 }
1208 AddPNode* address = base->in(Address)->as_AddP();
1209 Node* cache_base = address->in(AddPNode::Base);
1210 if ((cache_base != NULL) && cache_base->is_DecodeN()) {
1211 // Get ConP node which is static 'cache' field.
1212 cache_base = cache_base->in(1);
1213 }
1214 if ((cache_base != NULL) && cache_base->is_Con()) {
1215 const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr();
1216 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1217 Node* elements[4];
1218 int shift = exact_log2(type2aelembytes(T_OBJECT));
1219 int count = address->unpack_offsets(elements, ARRAY_SIZE(elements));
1220 if ((count > 0) && elements[0]->is_Con() &&
1221 ((count == 1) ||
1222 (count == 2) && elements[1]->Opcode() == Op_LShiftX &&
1223 elements[1]->in(2) == phase->intcon(shift))) {
1224 ciObjArray* array = base_type->const_oop()->as_obj_array();
1225 // Fetch the box object cache[0] at the base of the array and get its value
1226 ciInstance* box = array->obj_at(0)->as_instance();
1227 ciInstanceKlass* ik = box->klass()->as_instance_klass();
1228 assert(ik->is_box_klass(), "sanity");
1229 assert(ik->nof_nonstatic_fields() == 1, "change following code");
1230 if (ik->nof_nonstatic_fields() == 1) {
1231 // This should be true nonstatic_field_at requires calling
1232 // nof_nonstatic_fields so check it anyway
1233 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1234 BasicType bt = c.basic_type();
1235 // Only integer types have boxing cache.
1236 assert(bt == T_BOOLEAN || bt == T_CHAR ||
1237 bt == T_BYTE || bt == T_SHORT ||
1238 bt == T_INT || bt == T_LONG, "wrong type = %s", type2name(bt));
1239 jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int();
1240 if (cache_low != (int)cache_low) {
1241 return NULL; // should not happen since cache is array indexed by value
1242 }
1243 jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift);
1244 if (offset != (int)offset) {
1245 return NULL; // should not happen since cache is array indexed by value
1246 }
1247 // Add up all the offsets making of the address of the load
1248 Node* result = elements[0];
1249 for (int i = 1; i < count; i++) {
1250 result = phase->transform(new AddXNode(result, elements[i]));
1251 }
1252 // Remove the constant offset from the address and then
1253 result = phase->transform(new AddXNode(result, phase->MakeConX(-(int)offset)));
1254 // remove the scaling of the offset to recover the original index.
1255 if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) {
1256 // Peel the shift off directly but wrap it in a dummy node
1257 // since Ideal can't return existing nodes
1258 result = new RShiftXNode(result->in(1), phase->intcon(0));
1259 } else if (result->is_Add() && result->in(2)->is_Con() &&
1260 result->in(1)->Opcode() == Op_LShiftX &&
1261 result->in(1)->in(2) == phase->intcon(shift)) {
1262 // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z)
1263 // but for boxing cache access we know that X<<Z will not overflow
1264 // (there is range check) so we do this optimizatrion by hand here.
1265 Node* add_con = new RShiftXNode(result->in(2), phase->intcon(shift));
1266 result = new AddXNode(result->in(1)->in(1), phase->transform(add_con));
1267 } else {
1268 result = new RShiftXNode(result, phase->intcon(shift));
1269 }
1270 #ifdef _LP64
1271 if (bt != T_LONG) {
1272 result = new ConvL2INode(phase->transform(result));
1273 }
1274 #else
1275 if (bt == T_LONG) {
1276 result = new ConvI2LNode(phase->transform(result));
1277 }
1278 #endif
1279 // Boxing/unboxing can be done from signed & unsigned loads (e.g. LoadUB -> ... -> LoadB pair).
1280 // Need to preserve unboxing load type if it is unsigned.
1281 switch(this->Opcode()) {
1282 case Op_LoadUB:
1283 result = new AndINode(phase->transform(result), phase->intcon(0xFF));
1284 break;
1285 case Op_LoadUS:
1286 result = new AndINode(phase->transform(result), phase->intcon(0xFFFF));
1287 break;
1288 }
1289 return result;
1290 }
1291 }
1292 }
1293 }
1294 }
1295 return NULL;
1296 }
1297
1298 static bool stable_phi(PhiNode* phi, PhaseGVN *phase) {
1299 Node* region = phi->in(0);
1300 if (region == NULL) {
1301 return false; // Wait stable graph
1302 }
1303 uint cnt = phi->req();
1304 for (uint i = 1; i < cnt; i++) {
1305 Node* rc = region->in(i);
1306 if (rc == NULL || phase->type(rc) == Type::TOP)
1307 return false; // Wait stable graph
1308 Node* in = phi->in(i);
1309 if (in == NULL || phase->type(in) == Type::TOP)
1310 return false; // Wait stable graph
1311 }
1312 return true;
1313 }
1314 //------------------------------split_through_phi------------------------------
1315 // Split instance or boxed field load through Phi.
1316 Node *LoadNode::split_through_phi(PhaseGVN *phase) {
1317 Node* mem = in(Memory);
1318 Node* address = in(Address);
1319 const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr();
1320
1321 assert((t_oop != NULL) &&
1322 (t_oop->is_known_instance_field() ||
1323 t_oop->is_ptr_to_boxed_value()), "invalide conditions");
1324
1325 Compile* C = phase->C;
1326 intptr_t ignore = 0;
1327 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1328 bool base_is_phi = (base != NULL) && base->is_Phi();
1329 bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() &&
1330 (base != NULL) && (base == address->in(AddPNode::Base)) &&
1331 phase->type(base)->higher_equal(TypePtr::NOTNULL);
1332
1333 if (!((mem->is_Phi() || base_is_phi) &&
1334 (load_boxed_values || t_oop->is_known_instance_field()))) {
1335 return NULL; // memory is not Phi
1336 }
1337
1338 if (mem->is_Phi()) {
1339 if (!stable_phi(mem->as_Phi(), phase)) {
1340 return NULL; // Wait stable graph
1341 }
1342 uint cnt = mem->req();
1343 // Check for loop invariant memory.
1344 if (cnt == 3) {
1345 for (uint i = 1; i < cnt; i++) {
1346 Node* in = mem->in(i);
1347 Node* m = optimize_memory_chain(in, t_oop, this, phase);
1348 if (m == mem) {
1349 set_req(Memory, mem->in(cnt - i));
1350 return this; // made change
1351 }
1352 }
1353 }
1354 }
1355 if (base_is_phi) {
1356 if (!stable_phi(base->as_Phi(), phase)) {
1357 return NULL; // Wait stable graph
1358 }
1359 uint cnt = base->req();
1360 // Check for loop invariant memory.
1361 if (cnt == 3) {
1362 for (uint i = 1; i < cnt; i++) {
1363 if (base->in(i) == base) {
1364 return NULL; // Wait stable graph
1365 }
1366 }
1367 }
1368 }
1369
1370 bool load_boxed_phi = load_boxed_values && base_is_phi && (base->in(0) == mem->in(0));
1371
1372 // Split through Phi (see original code in loopopts.cpp).
1373 assert(C->have_alias_type(t_oop), "instance should have alias type");
1374
1375 // Do nothing here if Identity will find a value
1376 // (to avoid infinite chain of value phis generation).
1377 if (!phase->eqv(this, this->Identity(phase)))
1378 return NULL;
1379
1380 // Select Region to split through.
1381 Node* region;
1382 if (!base_is_phi) {
1383 assert(mem->is_Phi(), "sanity");
1384 region = mem->in(0);
1385 // Skip if the region dominates some control edge of the address.
1386 if (!MemNode::all_controls_dominate(address, region))
1387 return NULL;
1388 } else if (!mem->is_Phi()) {
1389 assert(base_is_phi, "sanity");
1390 region = base->in(0);
1391 // Skip if the region dominates some control edge of the memory.
1392 if (!MemNode::all_controls_dominate(mem, region))
1393 return NULL;
1394 } else if (base->in(0) != mem->in(0)) {
1395 assert(base_is_phi && mem->is_Phi(), "sanity");
1396 if (MemNode::all_controls_dominate(mem, base->in(0))) {
1397 region = base->in(0);
1398 } else if (MemNode::all_controls_dominate(address, mem->in(0))) {
1399 region = mem->in(0);
1400 } else {
1401 return NULL; // complex graph
1402 }
1403 } else {
1404 assert(base->in(0) == mem->in(0), "sanity");
1405 region = mem->in(0);
1406 }
1407
1408 const Type* this_type = this->bottom_type();
1409 int this_index = C->get_alias_index(t_oop);
1410 int this_offset = t_oop->offset();
1411 int this_iid = t_oop->instance_id();
1412 if (!t_oop->is_known_instance() && load_boxed_values) {
1413 // Use _idx of address base for boxed values.
1414 this_iid = base->_idx;
1415 }
1416 PhaseIterGVN* igvn = phase->is_IterGVN();
1417 Node* phi = new PhiNode(region, this_type, NULL, mem->_idx, this_iid, this_index, this_offset);
1418 for (uint i = 1; i < region->req(); i++) {
1419 Node* x;
1420 Node* the_clone = NULL;
1421 if (region->in(i) == C->top()) {
1422 x = C->top(); // Dead path? Use a dead data op
1423 } else {
1424 x = this->clone(); // Else clone up the data op
1425 the_clone = x; // Remember for possible deletion.
1426 // Alter data node to use pre-phi inputs
1427 if (this->in(0) == region) {
1428 x->set_req(0, region->in(i));
1429 } else {
1430 x->set_req(0, NULL);
1431 }
1432 if (mem->is_Phi() && (mem->in(0) == region)) {
1433 x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone.
1434 }
1435 if (address->is_Phi() && address->in(0) == region) {
1436 x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone
1437 }
1438 if (base_is_phi && (base->in(0) == region)) {
1439 Node* base_x = base->in(i); // Clone address for loads from boxed objects.
1440 Node* adr_x = phase->transform(new AddPNode(base_x,base_x,address->in(AddPNode::Offset)));
1441 x->set_req(Address, adr_x);
1442 }
1443 }
1444 // Check for a 'win' on some paths
1445 const Type *t = x->Value(igvn);
1446
1447 bool singleton = t->singleton();
1448
1449 // See comments in PhaseIdealLoop::split_thru_phi().
1450 if (singleton && t == Type::TOP) {
1451 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1452 }
1453
1454 if (singleton) {
1455 x = igvn->makecon(t);
1456 } else {
1457 // We now call Identity to try to simplify the cloned node.
1458 // Note that some Identity methods call phase->type(this).
1459 // Make sure that the type array is big enough for
1460 // our new node, even though we may throw the node away.
1461 // (This tweaking with igvn only works because x is a new node.)
1462 igvn->set_type(x, t);
1463 // If x is a TypeNode, capture any more-precise type permanently into Node
1464 // otherwise it will be not updated during igvn->transform since
1465 // igvn->type(x) is set to x->Value() already.
1466 x->raise_bottom_type(t);
1467 Node *y = x->Identity(igvn);
1468 if (y != x) {
1469 x = y;
1470 } else {
1471 y = igvn->hash_find_insert(x);
1472 if (y) {
1473 x = y;
1474 } else {
1475 // Else x is a new node we are keeping
1476 // We do not need register_new_node_with_optimizer
1477 // because set_type has already been called.
1478 igvn->_worklist.push(x);
1479 }
1480 }
1481 }
1482 if (x != the_clone && the_clone != NULL) {
1483 igvn->remove_dead_node(the_clone);
1484 }
1485 phi->set_req(i, x);
1486 }
1487 // Record Phi
1488 igvn->register_new_node_with_optimizer(phi);
1489 return phi;
1490 }
1491
1492 //------------------------------Ideal------------------------------------------
1493 // If the load is from Field memory and the pointer is non-null, it might be possible to
1494 // zero out the control input.
1495 // If the offset is constant and the base is an object allocation,
1496 // try to hook me up to the exact initializing store.
1497 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1498 Node* p = MemNode::Ideal_common(phase, can_reshape);
1499 if (p) return (p == NodeSentinel) ? NULL : p;
1500
1501 Node* ctrl = in(MemNode::Control);
1502 Node* address = in(MemNode::Address);
1503 bool progress = false;
1504
1505 // Skip up past a SafePoint control. Cannot do this for Stores because
1506 // pointer stores & cardmarks must stay on the same side of a SafePoint.
1507 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint &&
1508 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw ) {
1509 ctrl = ctrl->in(0);
1510 set_req(MemNode::Control,ctrl);
1511 progress = true;
1512 }
1513
1514 intptr_t ignore = 0;
1515 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1516 if (base != NULL
1517 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
1518 // Check for useless control edge in some common special cases
1519 if (in(MemNode::Control) != NULL
1520 && can_remove_control()
1521 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1522 && all_controls_dominate(base, phase->C->start())) {
1523 // A method-invariant, non-null address (constant or 'this' argument).
1524 set_req(MemNode::Control, NULL);
1525 progress = true;
1526 }
1527 }
1528
1529 Node* mem = in(MemNode::Memory);
1530 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1531
1532 if (can_reshape && (addr_t != NULL)) {
1533 // try to optimize our memory input
1534 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase);
1535 if (opt_mem != mem) {
1536 set_req(MemNode::Memory, opt_mem);
1537 if (phase->type( opt_mem ) == Type::TOP) return NULL;
1538 return this;
1539 }
1540 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1541 if ((t_oop != NULL) &&
1542 (t_oop->is_known_instance_field() ||
1543 t_oop->is_ptr_to_boxed_value())) {
1544 PhaseIterGVN *igvn = phase->is_IterGVN();
1545 if (igvn != NULL && igvn->_worklist.member(opt_mem)) {
1546 // Delay this transformation until memory Phi is processed.
1547 phase->is_IterGVN()->_worklist.push(this);
1548 return NULL;
1549 }
1550 // Split instance field load through Phi.
1551 Node* result = split_through_phi(phase);
1552 if (result != NULL) return result;
1553
1554 if (t_oop->is_ptr_to_boxed_value()) {
1555 Node* result = eliminate_autobox(phase);
1556 if (result != NULL) return result;
1557 }
1558 }
1559 }
1560
1561 // Is there a dominating load that loads the same value? Leave
1562 // anything that is not a load of a field/array element (like
1563 // barriers etc.) alone
1564 if (in(0) != NULL && adr_type() != TypeRawPtr::BOTTOM && can_reshape) {
1565 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) {
1566 Node *use = mem->fast_out(i);
1567 if (use != this &&
1568 use->Opcode() == Opcode() &&
1569 use->in(0) != NULL &&
1570 use->in(0) != in(0) &&
1571 use->in(Address) == in(Address)) {
1572 Node* ctl = in(0);
1573 for (int i = 0; i < 10 && ctl != NULL; i++) {
1574 ctl = IfNode::up_one_dom(ctl);
1575 if (ctl == use->in(0)) {
1576 set_req(0, use->in(0));
1577 return this;
1578 }
1579 }
1580 }
1581 }
1582 }
1583
1584 // Check for prior store with a different base or offset; make Load
1585 // independent. Skip through any number of them. Bail out if the stores
1586 // are in an endless dead cycle and report no progress. This is a key
1587 // transform for Reflection. However, if after skipping through the Stores
1588 // we can't then fold up against a prior store do NOT do the transform as
1589 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
1590 // array memory alive twice: once for the hoisted Load and again after the
1591 // bypassed Store. This situation only works if EVERYBODY who does
1592 // anti-dependence work knows how to bypass. I.e. we need all
1593 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
1594 // the alias index stuff. So instead, peek through Stores and IFF we can
1595 // fold up, do so.
1596 Node* prev_mem = find_previous_store(phase);
1597 if (prev_mem != NULL) {
1598 Node* value = can_see_arraycopy_value(prev_mem, phase);
1599 if (value != NULL) {
1600 return value;
1601 }
1602 }
1603 // Steps (a), (b): Walk past independent stores to find an exact match.
1604 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) {
1605 // (c) See if we can fold up on the spot, but don't fold up here.
1606 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
1607 // just return a prior value, which is done by Identity calls.
1608 if (can_see_stored_value(prev_mem, phase)) {
1609 // Make ready for step (d):
1610 set_req(MemNode::Memory, prev_mem);
1611 return this;
1612 }
1613 }
1614
1615 return progress ? this : NULL;
1616 }
1617
1618 // Helper to recognize certain Klass fields which are invariant across
1619 // some group of array types (e.g., int[] or all T[] where T < Object).
1620 const Type*
1621 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1622 ciKlass* klass) const {
1623 if (tkls->offset() == in_bytes(Klass::modifier_flags_offset())) {
1624 // The field is Klass::_modifier_flags. Return its (constant) value.
1625 // (Folds up the 2nd indirection in aClassConstant.getModifiers().)
1626 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags");
1627 return TypeInt::make(klass->modifier_flags());
1628 }
1629 if (tkls->offset() == in_bytes(Klass::access_flags_offset())) {
1630 // The field is Klass::_access_flags. Return its (constant) value.
1631 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1632 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags");
1633 return TypeInt::make(klass->access_flags());
1634 }
1635 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) {
1636 // The field is Klass::_layout_helper. Return its constant value if known.
1637 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper");
1638 return TypeInt::make(klass->layout_helper());
1639 }
1640
1641 // No match.
1642 return NULL;
1643 }
1644
1645 //------------------------------Value-----------------------------------------
1646 const Type* LoadNode::Value(PhaseGVN* phase) const {
1647 // Either input is TOP ==> the result is TOP
1648 Node* mem = in(MemNode::Memory);
1649 const Type *t1 = phase->type(mem);
1650 if (t1 == Type::TOP) return Type::TOP;
1651 Node* adr = in(MemNode::Address);
1652 const TypePtr* tp = phase->type(adr)->isa_ptr();
1653 if (tp == NULL || tp->empty()) return Type::TOP;
1654 int off = tp->offset();
1655 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
1656 Compile* C = phase->C;
1657
1658 // Try to guess loaded type from pointer type
1659 if (tp->isa_aryptr()) {
1660 const TypeAryPtr* ary = tp->is_aryptr();
1661 const Type* t = ary->elem();
1662
1663 // Determine whether the reference is beyond the header or not, by comparing
1664 // the offset against the offset of the start of the array's data.
1665 // Different array types begin at slightly different offsets (12 vs. 16).
1666 // We choose T_BYTE as an example base type that is least restrictive
1667 // as to alignment, which will therefore produce the smallest
1668 // possible base offset.
1669 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
1670 const bool off_beyond_header = ((uint)off >= (uint)min_base_off);
1671
1672 // Try to constant-fold a stable array element.
1673 if (FoldStableValues && !is_mismatched_access() && ary->is_stable()) {
1674 // Make sure the reference is not into the header and the offset is constant
1675 ciObject* aobj = ary->const_oop();
1676 if (aobj != NULL && off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) {
1677 int stable_dimension = (ary->stable_dimension() > 0 ? ary->stable_dimension() - 1 : 0);
1678 const Type* con_type = Type::make_constant_from_array_element(aobj->as_array(), off,
1679 stable_dimension,
1680 memory_type(), is_unsigned());
1681 if (con_type != NULL) {
1682 return con_type;
1683 }
1684 }
1685 }
1686
1687 // Don't do this for integer types. There is only potential profit if
1688 // the element type t is lower than _type; that is, for int types, if _type is
1689 // more restrictive than t. This only happens here if one is short and the other
1690 // char (both 16 bits), and in those cases we've made an intentional decision
1691 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
1692 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
1693 //
1694 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
1695 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
1696 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
1697 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
1698 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
1699 // In fact, that could have been the original type of p1, and p1 could have
1700 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
1701 // expression (LShiftL quux 3) independently optimized to the constant 8.
1702 if ((t->isa_int() == NULL) && (t->isa_long() == NULL)
1703 && (_type->isa_vect() == NULL)
1704 && t->isa_valuetype() == NULL
1705 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
1706 // t might actually be lower than _type, if _type is a unique
1707 // concrete subclass of abstract class t.
1708 if (off_beyond_header) { // is the offset beyond the header?
1709 const Type* jt = t->join_speculative(_type);
1710 // In any case, do not allow the join, per se, to empty out the type.
1711 if (jt->empty() && !t->empty()) {
1712 // This can happen if a interface-typed array narrows to a class type.
1713 jt = _type;
1714 }
1715 #ifdef ASSERT
1716 if (phase->C->eliminate_boxing() && adr->is_AddP()) {
1717 // The pointers in the autobox arrays are always non-null
1718 Node* base = adr->in(AddPNode::Base);
1719 if ((base != NULL) && base->is_DecodeN()) {
1720 // Get LoadN node which loads IntegerCache.cache field
1721 base = base->in(1);
1722 }
1723 if ((base != NULL) && base->is_Con()) {
1724 const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr();
1725 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1726 // It could be narrow oop
1727 assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity");
1728 }
1729 }
1730 }
1731 #endif
1732 return jt;
1733 }
1734 }
1735 } else if (tp->base() == Type::InstPtr) {
1736 assert( off != Type::OffsetBot ||
1737 // arrays can be cast to Objects
1738 tp->is_oopptr()->klass()->is_java_lang_Object() ||
1739 // unsafe field access may not have a constant offset
1740 C->has_unsafe_access(),
1741 "Field accesses must be precise" );
1742 // For oop loads, we expect the _type to be precise.
1743
1744 // Optimize loads from constant fields.
1745 const TypeInstPtr* tinst = tp->is_instptr();
1746 ciObject* const_oop = tinst->const_oop();
1747 if (!is_mismatched_access() && off != Type::OffsetBot && const_oop != NULL && const_oop->is_instance()) {
1748 const Type* con_type = Type::make_constant_from_field(const_oop->as_instance(), off, is_unsigned(), memory_type());
1749 if (con_type != NULL) {
1750 return con_type;
1751 }
1752 }
1753 } else if (tp->base() == Type::KlassPtr) {
1754 assert( off != Type::OffsetBot ||
1755 // arrays can be cast to Objects
1756 tp->is_klassptr()->klass()->is_java_lang_Object() ||
1757 // also allow array-loading from the primary supertype
1758 // array during subtype checks
1759 Opcode() == Op_LoadKlass,
1760 "Field accesses must be precise" );
1761 // For klass/static loads, we expect the _type to be precise
1762 }
1763
1764 const TypeKlassPtr *tkls = tp->isa_klassptr();
1765 if (tkls != NULL && !StressReflectiveCode) {
1766 ciKlass* klass = tkls->klass();
1767 if (klass->is_loaded() && tkls->klass_is_exact()) {
1768 // We are loading a field from a Klass metaobject whose identity
1769 // is known at compile time (the type is "exact" or "precise").
1770 // Check for fields we know are maintained as constants by the VM.
1771 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) {
1772 // The field is Klass::_super_check_offset. Return its (constant) value.
1773 // (Folds up type checking code.)
1774 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
1775 return TypeInt::make(klass->super_check_offset());
1776 }
1777 // Compute index into primary_supers array
1778 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1779 // Check for overflowing; use unsigned compare to handle the negative case.
1780 if( depth < ciKlass::primary_super_limit() ) {
1781 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1782 // (Folds up type checking code.)
1783 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1784 ciKlass *ss = klass->super_of_depth(depth);
1785 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1786 }
1787 const Type* aift = load_array_final_field(tkls, klass);
1788 if (aift != NULL) return aift;
1789 if (tkls->offset() == in_bytes(Klass::java_mirror_offset())) {
1790 // The field is Klass::_java_mirror. Return its (constant) value.
1791 // (Folds up the 2nd indirection in anObjConstant.getClass().)
1792 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
1793 return TypeInstPtr::make(klass->java_mirror());
1794 }
1795 }
1796
1797 // We can still check if we are loading from the primary_supers array at a
1798 // shallow enough depth. Even though the klass is not exact, entries less
1799 // than or equal to its super depth are correct.
1800 if (klass->is_loaded() ) {
1801 ciType *inner = klass;
1802 while( inner->is_obj_array_klass() )
1803 inner = inner->as_obj_array_klass()->base_element_type();
1804 if( inner->is_instance_klass() &&
1805 !inner->as_instance_klass()->flags().is_interface() ) {
1806 // Compute index into primary_supers array
1807 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1808 // Check for overflowing; use unsigned compare to handle the negative case.
1809 if( depth < ciKlass::primary_super_limit() &&
1810 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case
1811 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1812 // (Folds up type checking code.)
1813 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1814 ciKlass *ss = klass->super_of_depth(depth);
1815 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1816 }
1817 }
1818 }
1819
1820 // If the type is enough to determine that the thing is not an array,
1821 // we can give the layout_helper a positive interval type.
1822 // This will help short-circuit some reflective code.
1823 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())
1824 && !klass->is_array_klass() // not directly typed as an array
1825 && !klass->is_interface() // specifically not Serializable & Cloneable
1826 && !klass->is_java_lang_Object() // not the supertype of all T[]
1827 ) {
1828 // Note: When interfaces are reliable, we can narrow the interface
1829 // test to (klass != Serializable && klass != Cloneable).
1830 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
1831 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
1832 // The key property of this type is that it folds up tests
1833 // for array-ness, since it proves that the layout_helper is positive.
1834 // Thus, a generic value like the basic object layout helper works fine.
1835 return TypeInt::make(min_size, max_jint, Type::WidenMin);
1836 }
1837 }
1838
1839 // If we are loading from a freshly-allocated object, produce a zero,
1840 // if the load is provably beyond the header of the object.
1841 // (Also allow a variable load from a fresh array to produce zero.)
1842 const TypeOopPtr *tinst = tp->isa_oopptr();
1843 bool is_instance = (tinst != NULL) && tinst->is_known_instance_field();
1844 bool is_boxed_value = (tinst != NULL) && tinst->is_ptr_to_boxed_value();
1845 if (ReduceFieldZeroing || is_instance || is_boxed_value) {
1846 Node* value = can_see_stored_value(mem,phase);
1847 if (value != NULL && value->is_Con()) {
1848 assert(value->bottom_type()->higher_equal(_type),"sanity");
1849 return value->bottom_type();
1850 }
1851 }
1852
1853 if (is_instance) {
1854 // If we have an instance type and our memory input is the
1855 // programs's initial memory state, there is no matching store,
1856 // so just return a zero of the appropriate type
1857 Node *mem = in(MemNode::Memory);
1858 if (mem->is_Parm() && mem->in(0)->is_Start()) {
1859 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
1860 return Type::get_zero_type(_type->basic_type());
1861 }
1862 }
1863 return _type;
1864 }
1865
1866 //------------------------------match_edge-------------------------------------
1867 // Do we Match on this edge index or not? Match only the address.
1868 uint LoadNode::match_edge(uint idx) const {
1869 return idx == MemNode::Address;
1870 }
1871
1872 //--------------------------LoadBNode::Ideal--------------------------------------
1873 //
1874 // If the previous store is to the same address as this load,
1875 // and the value stored was larger than a byte, replace this load
1876 // with the value stored truncated to a byte. If no truncation is
1877 // needed, the replacement is done in LoadNode::Identity().
1878 //
1879 Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1880 Node* mem = in(MemNode::Memory);
1881 Node* value = can_see_stored_value(mem,phase);
1882 if( value && !phase->type(value)->higher_equal( _type ) ) {
1883 Node *result = phase->transform( new LShiftINode(value, phase->intcon(24)) );
1884 return new RShiftINode(result, phase->intcon(24));
1885 }
1886 // Identity call will handle the case where truncation is not needed.
1887 return LoadNode::Ideal(phase, can_reshape);
1888 }
1889
1890 const Type* LoadBNode::Value(PhaseGVN* phase) const {
1891 Node* mem = in(MemNode::Memory);
1892 Node* value = can_see_stored_value(mem,phase);
1893 if (value != NULL && value->is_Con() &&
1894 !value->bottom_type()->higher_equal(_type)) {
1895 // If the input to the store does not fit with the load's result type,
1896 // it must be truncated. We can't delay until Ideal call since
1897 // a singleton Value is needed for split_thru_phi optimization.
1898 int con = value->get_int();
1899 return TypeInt::make((con << 24) >> 24);
1900 }
1901 return LoadNode::Value(phase);
1902 }
1903
1904 //--------------------------LoadUBNode::Ideal-------------------------------------
1905 //
1906 // If the previous store is to the same address as this load,
1907 // and the value stored was larger than a byte, replace this load
1908 // with the value stored truncated to a byte. If no truncation is
1909 // needed, the replacement is done in LoadNode::Identity().
1910 //
1911 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
1912 Node* mem = in(MemNode::Memory);
1913 Node* value = can_see_stored_value(mem, phase);
1914 if (value && !phase->type(value)->higher_equal(_type))
1915 return new AndINode(value, phase->intcon(0xFF));
1916 // Identity call will handle the case where truncation is not needed.
1917 return LoadNode::Ideal(phase, can_reshape);
1918 }
1919
1920 const Type* LoadUBNode::Value(PhaseGVN* 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 & 0xFF);
1930 }
1931 return LoadNode::Value(phase);
1932 }
1933
1934 //--------------------------LoadUSNode::Ideal-------------------------------------
1935 //
1936 // If the previous store is to the same address as this load,
1937 // and the value stored was larger than a char, replace this load
1938 // with the value stored truncated to a char. If no truncation is
1939 // needed, the replacement is done in LoadNode::Identity().
1940 //
1941 Node *LoadUSNode::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 AndINode(value,phase->intcon(0xFFFF));
1946 // Identity call will handle the case where truncation is not needed.
1947 return LoadNode::Ideal(phase, can_reshape);
1948 }
1949
1950 const Type* LoadUSNode::Value(PhaseGVN* 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 & 0xFFFF);
1960 }
1961 return LoadNode::Value(phase);
1962 }
1963
1964 //--------------------------LoadSNode::Ideal--------------------------------------
1965 //
1966 // If the previous store is to the same address as this load,
1967 // and the value stored was larger than a short, replace this load
1968 // with the value stored truncated to a short. If no truncation is
1969 // needed, the replacement is done in LoadNode::Identity().
1970 //
1971 Node *LoadSNode::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 Node *result = phase->transform( new LShiftINode(value, phase->intcon(16)) );
1976 return new RShiftINode(result, phase->intcon(16));
1977 }
1978 // Identity call will handle the case where truncation is not needed.
1979 return LoadNode::Ideal(phase, can_reshape);
1980 }
1981
1982 const Type* LoadSNode::Value(PhaseGVN* phase) const {
1983 Node* mem = in(MemNode::Memory);
1984 Node* value = can_see_stored_value(mem,phase);
1985 if (value != NULL && value->is_Con() &&
1986 !value->bottom_type()->higher_equal(_type)) {
1987 // If the input to the store does not fit with the load's result type,
1988 // it must be truncated. We can't delay until Ideal call since
1989 // a singleton Value is needed for split_thru_phi optimization.
1990 int con = value->get_int();
1991 return TypeInt::make((con << 16) >> 16);
1992 }
1993 return LoadNode::Value(phase);
1994 }
1995
1996 //=============================================================================
1997 //----------------------------LoadKlassNode::make------------------------------
1998 // Polymorphic factory method:
1999 Node* LoadKlassNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* at, const TypeKlassPtr* tk) {
2000 // sanity check the alias category against the created node type
2001 const TypePtr *adr_type = adr->bottom_type()->isa_ptr();
2002 assert(adr_type != NULL, "expecting TypeKlassPtr");
2003 #ifdef _LP64
2004 if (adr_type->is_ptr_to_narrowklass()) {
2005 assert(UseCompressedClassPointers, "no compressed klasses");
2006 Node* load_klass = gvn.transform(new LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowklass(), MemNode::unordered));
2007 return new DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr());
2008 }
2009 #endif
2010 assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
2011 return new LoadKlassNode(ctl, mem, adr, at, tk, MemNode::unordered);
2012 }
2013
2014 //------------------------------Value------------------------------------------
2015 const Type* LoadKlassNode::Value(PhaseGVN* phase) const {
2016 return klass_value_common(phase);
2017 }
2018
2019 // In most cases, LoadKlassNode does not have the control input set. If the control
2020 // input is set, it must not be removed (by LoadNode::Ideal()).
2021 bool LoadKlassNode::can_remove_control() const {
2022 return false;
2023 }
2024
2025 const Type* LoadNode::klass_value_common(PhaseGVN* phase) const {
2026 // Either input is TOP ==> the result is TOP
2027 const Type *t1 = phase->type( in(MemNode::Memory) );
2028 if (t1 == Type::TOP) return Type::TOP;
2029 Node *adr = in(MemNode::Address);
2030 const Type *t2 = phase->type( adr );
2031 if (t2 == Type::TOP) return Type::TOP;
2032 const TypePtr *tp = t2->is_ptr();
2033 if (TypePtr::above_centerline(tp->ptr()) ||
2034 tp->ptr() == TypePtr::Null) return Type::TOP;
2035
2036 // Return a more precise klass, if possible
2037 const TypeInstPtr *tinst = tp->isa_instptr();
2038 if (tinst != NULL) {
2039 ciInstanceKlass* ik = tinst->klass()->as_instance_klass();
2040 int offset = tinst->offset();
2041 if (ik == phase->C->env()->Class_klass()
2042 && (offset == java_lang_Class::klass_offset_in_bytes() ||
2043 offset == java_lang_Class::array_klass_offset_in_bytes())) {
2044 // We are loading a special hidden field from a Class mirror object,
2045 // the field which points to the VM's Klass metaobject.
2046 ciType* t = tinst->java_mirror_type();
2047 // java_mirror_type returns non-null for compile-time Class constants.
2048 if (t != NULL) {
2049 // constant oop => constant klass
2050 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
2051 if (t->is_void()) {
2052 // We cannot create a void array. Since void is a primitive type return null
2053 // klass. Users of this result need to do a null check on the returned klass.
2054 return TypePtr::NULL_PTR;
2055 }
2056 return TypeKlassPtr::make(ciArrayKlass::make(t));
2057 }
2058 if (!t->is_klass()) {
2059 // a primitive Class (e.g., int.class) has NULL for a klass field
2060 return TypePtr::NULL_PTR;
2061 }
2062 // (Folds up the 1st indirection in aClassConstant.getModifiers().)
2063 return TypeKlassPtr::make(t->as_klass());
2064 }
2065 // non-constant mirror, so we can't tell what's going on
2066 }
2067 if( !ik->is_loaded() )
2068 return _type; // Bail out if not loaded
2069 if (offset == oopDesc::klass_offset_in_bytes()) {
2070 if (tinst->klass_is_exact()) {
2071 return TypeKlassPtr::make(ik);
2072 }
2073 // See if we can become precise: no subklasses and no interface
2074 // (Note: We need to support verified interfaces.)
2075 if (!ik->is_interface() && !ik->has_subklass()) {
2076 //assert(!UseExactTypes, "this code should be useless with exact types");
2077 // Add a dependence; if any subclass added we need to recompile
2078 if (!ik->is_final()) {
2079 // %%% should use stronger assert_unique_concrete_subtype instead
2080 phase->C->dependencies()->assert_leaf_type(ik);
2081 }
2082 // Return precise klass
2083 return TypeKlassPtr::make(ik);
2084 }
2085
2086 // Return root of possible klass
2087 return TypeKlassPtr::make(TypePtr::NotNull, ik, Type::Offset(0));
2088 }
2089 }
2090
2091 // Check for loading klass from an array
2092 const TypeAryPtr *tary = tp->isa_aryptr();
2093 if( tary != NULL ) {
2094 ciKlass *tary_klass = tary->klass();
2095 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP
2096 && tary->offset() == oopDesc::klass_offset_in_bytes()) {
2097 if (tary->klass_is_exact()) {
2098 return TypeKlassPtr::make(tary_klass);
2099 }
2100 ciArrayKlass *ak = tary->klass()->as_array_klass();
2101 // If the klass is an object array, we defer the question to the
2102 // array component klass.
2103 if( ak->is_obj_array_klass() ) {
2104 assert( ak->is_loaded(), "" );
2105 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass();
2106 if( base_k->is_loaded() && base_k->is_instance_klass() ) {
2107 ciInstanceKlass* ik = base_k->as_instance_klass();
2108 // See if we can become precise: no subklasses and no interface
2109 if (!ik->is_interface() && !ik->has_subklass()) {
2110 //assert(!UseExactTypes, "this code should be useless with exact types");
2111 // Add a dependence; if any subclass added we need to recompile
2112 if (!ik->is_final()) {
2113 phase->C->dependencies()->assert_leaf_type(ik);
2114 }
2115 // Return precise array klass
2116 return TypeKlassPtr::make(ak);
2117 }
2118 }
2119 return TypeKlassPtr::make(TypePtr::NotNull, ak, Type::Offset(0));
2120 } else { // Found a type-array?
2121 //assert(!UseExactTypes, "this code should be useless with exact types");
2122 assert( ak->is_type_array_klass(), "" );
2123 return TypeKlassPtr::make(ak); // These are always precise
2124 }
2125 }
2126 }
2127
2128 // Check for loading klass from an array klass
2129 const TypeKlassPtr *tkls = tp->isa_klassptr();
2130 if (tkls != NULL && !StressReflectiveCode) {
2131 ciKlass* klass = tkls->klass();
2132 if( !klass->is_loaded() )
2133 return _type; // Bail out if not loaded
2134 if( klass->is_obj_array_klass() &&
2135 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) {
2136 ciKlass* elem = klass->as_obj_array_klass()->element_klass();
2137 // // Always returning precise element type is incorrect,
2138 // // e.g., element type could be object and array may contain strings
2139 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
2140
2141 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
2142 // according to the element type's subclassing.
2143 return TypeKlassPtr::make(tkls->ptr(), elem, Type::Offset(0));
2144 }
2145 if( klass->is_instance_klass() && tkls->klass_is_exact() &&
2146 tkls->offset() == in_bytes(Klass::super_offset())) {
2147 ciKlass* sup = klass->as_instance_klass()->super();
2148 // The field is Klass::_super. Return its (constant) value.
2149 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
2150 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR;
2151 }
2152 }
2153
2154 // Bailout case
2155 return LoadNode::Value(phase);
2156 }
2157
2158 //------------------------------Identity---------------------------------------
2159 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
2160 // Also feed through the klass in Allocate(...klass...)._klass.
2161 Node* LoadKlassNode::Identity(PhaseGVN* phase) {
2162 return klass_identity_common(phase);
2163 }
2164
2165 Node* LoadNode::klass_identity_common(PhaseGVN* phase) {
2166 Node* x = LoadNode::Identity(phase);
2167 if (x != this) return x;
2168
2169 // Take apart the address into an oop and and offset.
2170 // Return 'this' if we cannot.
2171 Node* adr = in(MemNode::Address);
2172 intptr_t offset = 0;
2173 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2174 if (base == NULL) return this;
2175 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
2176 if (toop == NULL) return this;
2177
2178 // We can fetch the klass directly through an AllocateNode.
2179 // This works even if the klass is not constant (clone or newArray).
2180 if (offset == oopDesc::klass_offset_in_bytes()) {
2181 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
2182 if (allocated_klass != NULL) {
2183 return allocated_klass;
2184 }
2185 }
2186
2187 // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*.
2188 // See inline_native_Class_query for occurrences of these patterns.
2189 // Java Example: x.getClass().isAssignableFrom(y)
2190 //
2191 // This improves reflective code, often making the Class
2192 // mirror go completely dead. (Current exception: Class
2193 // mirrors may appear in debug info, but we could clean them out by
2194 // introducing a new debug info operator for Klass*.java_mirror).
2195 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass()
2196 && offset == java_lang_Class::klass_offset_in_bytes()) {
2197 // We are loading a special hidden field from a Class mirror,
2198 // the field which points to its Klass or ArrayKlass metaobject.
2199 if (base->is_Load()) {
2200 Node* adr2 = base->in(MemNode::Address);
2201 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2202 if (tkls != NULL && !tkls->empty()
2203 && (tkls->klass()->is_instance_klass() ||
2204 tkls->klass()->is_array_klass())
2205 && adr2->is_AddP()
2206 ) {
2207 int mirror_field = in_bytes(Klass::java_mirror_offset());
2208 if (tkls->offset() == mirror_field) {
2209 return adr2->in(AddPNode::Base);
2210 }
2211 }
2212 }
2213 }
2214
2215 return this;
2216 }
2217
2218
2219 //------------------------------Value------------------------------------------
2220 const Type* LoadNKlassNode::Value(PhaseGVN* phase) const {
2221 const Type *t = klass_value_common(phase);
2222 if (t == Type::TOP)
2223 return t;
2224
2225 return t->make_narrowklass();
2226 }
2227
2228 //------------------------------Identity---------------------------------------
2229 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
2230 // Also feed through the klass in Allocate(...klass...)._klass.
2231 Node* LoadNKlassNode::Identity(PhaseGVN* phase) {
2232 Node *x = klass_identity_common(phase);
2233
2234 const Type *t = phase->type( x );
2235 if( t == Type::TOP ) return x;
2236 if( t->isa_narrowklass()) return x;
2237 assert (!t->isa_narrowoop(), "no narrow oop here");
2238
2239 return phase->transform(new EncodePKlassNode(x, t->make_narrowklass()));
2240 }
2241
2242 //------------------------------Value-----------------------------------------
2243 const Type* LoadRangeNode::Value(PhaseGVN* phase) const {
2244 // Either input is TOP ==> the result is TOP
2245 const Type *t1 = phase->type( in(MemNode::Memory) );
2246 if( t1 == Type::TOP ) return Type::TOP;
2247 Node *adr = in(MemNode::Address);
2248 const Type *t2 = phase->type( adr );
2249 if( t2 == Type::TOP ) return Type::TOP;
2250 const TypePtr *tp = t2->is_ptr();
2251 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
2252 const TypeAryPtr *tap = tp->isa_aryptr();
2253 if( !tap ) return _type;
2254 return tap->size();
2255 }
2256
2257 //-------------------------------Ideal---------------------------------------
2258 // Feed through the length in AllocateArray(...length...)._length.
2259 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2260 Node* p = MemNode::Ideal_common(phase, can_reshape);
2261 if (p) return (p == NodeSentinel) ? NULL : p;
2262
2263 // Take apart the address into an oop and and offset.
2264 // Return 'this' if we cannot.
2265 Node* adr = in(MemNode::Address);
2266 intptr_t offset = 0;
2267 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2268 if (base == NULL) return NULL;
2269 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2270 if (tary == NULL) return NULL;
2271
2272 // We can fetch the length directly through an AllocateArrayNode.
2273 // This works even if the length is not constant (clone or newArray).
2274 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2275 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2276 if (alloc != NULL) {
2277 Node* allocated_length = alloc->Ideal_length();
2278 Node* len = alloc->make_ideal_length(tary, phase);
2279 if (allocated_length != len) {
2280 // New CastII improves on this.
2281 return len;
2282 }
2283 }
2284 }
2285
2286 return NULL;
2287 }
2288
2289 //------------------------------Identity---------------------------------------
2290 // Feed through the length in AllocateArray(...length...)._length.
2291 Node* LoadRangeNode::Identity(PhaseGVN* phase) {
2292 Node* x = LoadINode::Identity(phase);
2293 if (x != this) return x;
2294
2295 // Take apart the address into an oop and and offset.
2296 // Return 'this' if we cannot.
2297 Node* adr = in(MemNode::Address);
2298 intptr_t offset = 0;
2299 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2300 if (base == NULL) return this;
2301 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2302 if (tary == NULL) return this;
2303
2304 // We can fetch the length directly through an AllocateArrayNode.
2305 // This works even if the length is not constant (clone or newArray).
2306 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2307 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2308 if (alloc != NULL) {
2309 Node* allocated_length = alloc->Ideal_length();
2310 // Do not allow make_ideal_length to allocate a CastII node.
2311 Node* len = alloc->make_ideal_length(tary, phase, false);
2312 if (allocated_length == len) {
2313 // Return allocated_length only if it would not be improved by a CastII.
2314 return allocated_length;
2315 }
2316 }
2317 }
2318
2319 return this;
2320
2321 }
2322
2323 //=============================================================================
2324 //---------------------------StoreNode::make-----------------------------------
2325 // Polymorphic factory method:
2326 StoreNode* StoreNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt, MemOrd mo) {
2327 assert((mo == unordered || mo == release), "unexpected");
2328 Compile* C = gvn.C;
2329 assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2330 ctl != NULL, "raw memory operations should have control edge");
2331
2332 switch (bt) {
2333 case T_BOOLEAN: val = gvn.transform(new AndINode(val, gvn.intcon(0x1))); // Fall through to T_BYTE case
2334 case T_BYTE: return new StoreBNode(ctl, mem, adr, adr_type, val, mo);
2335 case T_INT: return new StoreINode(ctl, mem, adr, adr_type, val, mo);
2336 case T_CHAR:
2337 case T_SHORT: return new StoreCNode(ctl, mem, adr, adr_type, val, mo);
2338 case T_LONG: return new StoreLNode(ctl, mem, adr, adr_type, val, mo);
2339 case T_FLOAT: return new StoreFNode(ctl, mem, adr, adr_type, val, mo);
2340 case T_DOUBLE: return new StoreDNode(ctl, mem, adr, adr_type, val, mo);
2341 case T_METADATA:
2342 case T_ADDRESS:
2343 case T_VALUETYPE:
2344 case T_OBJECT:
2345 #ifdef _LP64
2346 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
2347 val = gvn.transform(new EncodePNode(val, val->bottom_type()->make_narrowoop()));
2348 return new StoreNNode(ctl, mem, adr, adr_type, val, mo);
2349 } else if (adr->bottom_type()->is_ptr_to_narrowklass() ||
2350 (UseCompressedClassPointers && val->bottom_type()->isa_klassptr() &&
2351 adr->bottom_type()->isa_rawptr())) {
2352 val = gvn.transform(new EncodePKlassNode(val, val->bottom_type()->make_narrowklass()));
2353 return new StoreNKlassNode(ctl, mem, adr, adr_type, val, mo);
2354 }
2355 #endif
2356 {
2357 return new StorePNode(ctl, mem, adr, adr_type, val, mo);
2358 }
2359 }
2360 ShouldNotReachHere();
2361 return (StoreNode*)NULL;
2362 }
2363
2364 StoreLNode* StoreLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
2365 bool require_atomic = true;
2366 return new StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
2367 }
2368
2369 StoreDNode* StoreDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
2370 bool require_atomic = true;
2371 return new StoreDNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
2372 }
2373
2374
2375 //--------------------------bottom_type----------------------------------------
2376 const Type *StoreNode::bottom_type() const {
2377 return Type::MEMORY;
2378 }
2379
2380 //------------------------------hash-------------------------------------------
2381 uint StoreNode::hash() const {
2382 // unroll addition of interesting fields
2383 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2384
2385 // Since they are not commoned, do not hash them:
2386 return NO_HASH;
2387 }
2388
2389 //------------------------------Ideal------------------------------------------
2390 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
2391 // When a store immediately follows a relevant allocation/initialization,
2392 // try to capture it into the initialization, or hoist it above.
2393 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2394 Node* p = MemNode::Ideal_common(phase, can_reshape);
2395 if (p) return (p == NodeSentinel) ? NULL : p;
2396
2397 Node* mem = in(MemNode::Memory);
2398 Node* address = in(MemNode::Address);
2399 // Back-to-back stores to same address? Fold em up. Generally
2400 // unsafe if I have intervening uses... Also disallowed for StoreCM
2401 // since they must follow each StoreP operation. Redundant StoreCMs
2402 // are eliminated just before matching in final_graph_reshape.
2403 {
2404 Node* st = mem;
2405 // If Store 'st' has more than one use, we cannot fold 'st' away.
2406 // For example, 'st' might be the final state at a conditional
2407 // return. Or, 'st' might be used by some node which is live at
2408 // the same time 'st' is live, which might be unschedulable. So,
2409 // require exactly ONE user until such time as we clone 'mem' for
2410 // each of 'mem's uses (thus making the exactly-1-user-rule hold
2411 // true).
2412 while (st->is_Store() && st->outcnt() == 1 && st->Opcode() != Op_StoreCM) {
2413 // Looking at a dead closed cycle of memory?
2414 assert(st != st->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
2415 assert(Opcode() == st->Opcode() ||
2416 st->Opcode() == Op_StoreVector ||
2417 Opcode() == Op_StoreVector ||
2418 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw ||
2419 (Opcode() == Op_StoreL && st->Opcode() == Op_StoreI) || // expanded ClearArrayNode
2420 (is_mismatched_access() || st->as_Store()->is_mismatched_access()),
2421 "no mismatched stores, except on raw memory: %s %s", NodeClassNames[Opcode()], NodeClassNames[st->Opcode()]);
2422
2423 if (st->in(MemNode::Address)->eqv_uncast(address) &&
2424 st->as_Store()->memory_size() <= this->memory_size()) {
2425 Node* use = st->raw_out(0);
2426 phase->igvn_rehash_node_delayed(use);
2427 if (can_reshape) {
2428 use->set_req_X(MemNode::Memory, st->in(MemNode::Memory), phase->is_IterGVN());
2429 } else {
2430 // It's OK to do this in the parser, since DU info is always accurate,
2431 // and the parser always refers to nodes via SafePointNode maps.
2432 use->set_req(MemNode::Memory, st->in(MemNode::Memory));
2433 }
2434 return this;
2435 }
2436 st = st->in(MemNode::Memory);
2437 }
2438 }
2439
2440
2441 // Capture an unaliased, unconditional, simple store into an initializer.
2442 // Or, if it is independent of the allocation, hoist it above the allocation.
2443 if (ReduceFieldZeroing && /*can_reshape &&*/
2444 mem->is_Proj() && mem->in(0)->is_Initialize()) {
2445 InitializeNode* init = mem->in(0)->as_Initialize();
2446 intptr_t offset = init->can_capture_store(this, phase, can_reshape);
2447 if (offset > 0) {
2448 Node* moved = init->capture_store(this, offset, phase, can_reshape);
2449 // If the InitializeNode captured me, it made a raw copy of me,
2450 // and I need to disappear.
2451 if (moved != NULL) {
2452 // %%% hack to ensure that Ideal returns a new node:
2453 mem = MergeMemNode::make(mem);
2454 return mem; // fold me away
2455 }
2456 }
2457 }
2458
2459 return NULL; // No further progress
2460 }
2461
2462 //------------------------------Value-----------------------------------------
2463 const Type* StoreNode::Value(PhaseGVN* phase) const {
2464 // Either input is TOP ==> the result is TOP
2465 const Type *t1 = phase->type( in(MemNode::Memory) );
2466 if( t1 == Type::TOP ) return Type::TOP;
2467 const Type *t2 = phase->type( in(MemNode::Address) );
2468 if( t2 == Type::TOP ) return Type::TOP;
2469 const Type *t3 = phase->type( in(MemNode::ValueIn) );
2470 if( t3 == Type::TOP ) return Type::TOP;
2471 return Type::MEMORY;
2472 }
2473
2474 //------------------------------Identity---------------------------------------
2475 // Remove redundant stores:
2476 // Store(m, p, Load(m, p)) changes to m.
2477 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
2478 Node* StoreNode::Identity(PhaseGVN* phase) {
2479 Node* mem = in(MemNode::Memory);
2480 Node* adr = in(MemNode::Address);
2481 Node* val = in(MemNode::ValueIn);
2482
2483 // Load then Store? Then the Store is useless
2484 if (val->is_Load() &&
2485 val->in(MemNode::Address)->eqv_uncast(adr) &&
2486 val->in(MemNode::Memory )->eqv_uncast(mem) &&
2487 val->as_Load()->store_Opcode() == Opcode()) {
2488 return mem;
2489 }
2490
2491 // Two stores in a row of the same value?
2492 if (mem->is_Store() &&
2493 mem->in(MemNode::Address)->eqv_uncast(adr) &&
2494 mem->in(MemNode::ValueIn)->eqv_uncast(val) &&
2495 mem->Opcode() == Opcode()) {
2496 return mem;
2497 }
2498
2499 // Store of zero anywhere into a freshly-allocated object?
2500 // Then the store is useless.
2501 // (It must already have been captured by the InitializeNode.)
2502 if (ReduceFieldZeroing && phase->type(val)->is_zero_type()) {
2503 // a newly allocated object is already all-zeroes everywhere
2504 if (mem->is_Proj() && mem->in(0)->is_Allocate()) {
2505 return mem;
2506 }
2507
2508 // the store may also apply to zero-bits in an earlier object
2509 Node* prev_mem = find_previous_store(phase);
2510 // Steps (a), (b): Walk past independent stores to find an exact match.
2511 if (prev_mem != NULL) {
2512 Node* prev_val = can_see_stored_value(prev_mem, phase);
2513 if (prev_val != NULL && phase->eqv(prev_val, val)) {
2514 // prev_val and val might differ by a cast; it would be good
2515 // to keep the more informative of the two.
2516 return mem;
2517 }
2518 }
2519 }
2520
2521 return this;
2522 }
2523
2524 //------------------------------match_edge-------------------------------------
2525 // Do we Match on this edge index or not? Match only memory & value
2526 uint StoreNode::match_edge(uint idx) const {
2527 return idx == MemNode::Address || idx == MemNode::ValueIn;
2528 }
2529
2530 //------------------------------cmp--------------------------------------------
2531 // Do not common stores up together. They generally have to be split
2532 // back up anyways, so do not bother.
2533 uint StoreNode::cmp( const Node &n ) const {
2534 return (&n == this); // Always fail except on self
2535 }
2536
2537 //------------------------------Ideal_masked_input-----------------------------
2538 // Check for a useless mask before a partial-word store
2539 // (StoreB ... (AndI valIn conIa) )
2540 // If (conIa & mask == mask) this simplifies to
2541 // (StoreB ... (valIn) )
2542 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
2543 Node *val = in(MemNode::ValueIn);
2544 if( val->Opcode() == Op_AndI ) {
2545 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2546 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
2547 set_req(MemNode::ValueIn, val->in(1));
2548 return this;
2549 }
2550 }
2551 return NULL;
2552 }
2553
2554
2555 //------------------------------Ideal_sign_extended_input----------------------
2556 // Check for useless sign-extension before a partial-word store
2557 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) )
2558 // If (conIL == conIR && conIR <= num_bits) this simplifies to
2559 // (StoreB ... (valIn) )
2560 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) {
2561 Node *val = in(MemNode::ValueIn);
2562 if( val->Opcode() == Op_RShiftI ) {
2563 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2564 if( t && t->is_con() && (t->get_con() <= num_bits) ) {
2565 Node *shl = val->in(1);
2566 if( shl->Opcode() == Op_LShiftI ) {
2567 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int();
2568 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) {
2569 set_req(MemNode::ValueIn, shl->in(1));
2570 return this;
2571 }
2572 }
2573 }
2574 }
2575 return NULL;
2576 }
2577
2578 //------------------------------value_never_loaded-----------------------------------
2579 // Determine whether there are any possible loads of the value stored.
2580 // For simplicity, we actually check if there are any loads from the
2581 // address stored to, not just for loads of the value stored by this node.
2582 //
2583 bool StoreNode::value_never_loaded( PhaseTransform *phase) const {
2584 Node *adr = in(Address);
2585 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
2586 if (adr_oop == NULL)
2587 return false;
2588 if (!adr_oop->is_known_instance_field())
2589 return false; // if not a distinct instance, there may be aliases of the address
2590 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
2591 Node *use = adr->fast_out(i);
2592 if (use->is_Load() || use->is_LoadStore()) {
2593 return false;
2594 }
2595 }
2596 return true;
2597 }
2598
2599 //=============================================================================
2600 //------------------------------Ideal------------------------------------------
2601 // If the store is from an AND mask that leaves the low bits untouched, then
2602 // we can skip the AND operation. If the store is from a sign-extension
2603 // (a left shift, then right shift) we can skip both.
2604 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
2605 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
2606 if( progress != NULL ) return progress;
2607
2608 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
2609 if( progress != NULL ) return progress;
2610
2611 // Finally check the default case
2612 return StoreNode::Ideal(phase, can_reshape);
2613 }
2614
2615 //=============================================================================
2616 //------------------------------Ideal------------------------------------------
2617 // If the store is from an AND mask that leaves the low bits untouched, then
2618 // we can skip the AND operation
2619 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
2620 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
2621 if( progress != NULL ) return progress;
2622
2623 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
2624 if( progress != NULL ) return progress;
2625
2626 // Finally check the default case
2627 return StoreNode::Ideal(phase, can_reshape);
2628 }
2629
2630 //=============================================================================
2631 //------------------------------Identity---------------------------------------
2632 Node* StoreCMNode::Identity(PhaseGVN* phase) {
2633 // No need to card mark when storing a null ptr
2634 Node* my_store = in(MemNode::OopStore);
2635 if (my_store->is_Store()) {
2636 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) );
2637 if( t1 == TypePtr::NULL_PTR ) {
2638 return in(MemNode::Memory);
2639 }
2640 }
2641 return this;
2642 }
2643
2644 //=============================================================================
2645 //------------------------------Ideal---------------------------------------
2646 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){
2647 Node* progress = StoreNode::Ideal(phase, can_reshape);
2648 if (progress != NULL) return progress;
2649
2650 Node* my_store = in(MemNode::OopStore);
2651 if (my_store->is_MergeMem()) {
2652 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx());
2653 set_req(MemNode::OopStore, mem);
2654 return this;
2655 }
2656
2657 return NULL;
2658 }
2659
2660 //------------------------------Value-----------------------------------------
2661 const Type* StoreCMNode::Value(PhaseGVN* phase) const {
2662 // Either input is TOP ==> the result is TOP
2663 const Type *t = phase->type( in(MemNode::Memory) );
2664 if( t == Type::TOP ) return Type::TOP;
2665 t = phase->type( in(MemNode::Address) );
2666 if( t == Type::TOP ) return Type::TOP;
2667 t = phase->type( in(MemNode::ValueIn) );
2668 if( t == Type::TOP ) return Type::TOP;
2669 // If extra input is TOP ==> the result is TOP
2670 t = phase->type( in(MemNode::OopStore) );
2671 if( t == Type::TOP ) return Type::TOP;
2672
2673 return StoreNode::Value( phase );
2674 }
2675
2676
2677 //=============================================================================
2678 //----------------------------------SCMemProjNode------------------------------
2679 const Type* SCMemProjNode::Value(PhaseGVN* phase) const
2680 {
2681 return bottom_type();
2682 }
2683
2684 //=============================================================================
2685 //----------------------------------LoadStoreNode------------------------------
2686 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required )
2687 : Node(required),
2688 _type(rt),
2689 _adr_type(at)
2690 {
2691 init_req(MemNode::Control, c );
2692 init_req(MemNode::Memory , mem);
2693 init_req(MemNode::Address, adr);
2694 init_req(MemNode::ValueIn, val);
2695 init_class_id(Class_LoadStore);
2696 }
2697
2698 uint LoadStoreNode::ideal_reg() const {
2699 return _type->ideal_reg();
2700 }
2701
2702 bool LoadStoreNode::result_not_used() const {
2703 for( DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++ ) {
2704 Node *x = fast_out(i);
2705 if (x->Opcode() == Op_SCMemProj) continue;
2706 return false;
2707 }
2708 return true;
2709 }
2710
2711 uint LoadStoreNode::size_of() const { return sizeof(*this); }
2712
2713 //=============================================================================
2714 //----------------------------------LoadStoreConditionalNode--------------------
2715 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, NULL, TypeInt::BOOL, 5) {
2716 init_req(ExpectedIn, ex );
2717 }
2718
2719 //=============================================================================
2720 //-------------------------------adr_type--------------------------------------
2721 const TypePtr* ClearArrayNode::adr_type() const {
2722 Node *adr = in(3);
2723 if (adr == NULL) return NULL; // node is dead
2724 return MemNode::calculate_adr_type(adr->bottom_type());
2725 }
2726
2727 //------------------------------match_edge-------------------------------------
2728 // Do we Match on this edge index or not? Do not match memory
2729 uint ClearArrayNode::match_edge(uint idx) const {
2730 return idx > 1;
2731 }
2732
2733 //------------------------------Identity---------------------------------------
2734 // Clearing a zero length array does nothing
2735 Node* ClearArrayNode::Identity(PhaseGVN* phase) {
2736 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
2737 }
2738
2739 //------------------------------Idealize---------------------------------------
2740 // Clearing a short array is faster with stores
2741 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2742 // Already know this is a large node, do not try to ideal it
2743 if (!IdealizeClearArrayNode || _is_large) return NULL;
2744
2745 const int unit = BytesPerLong;
2746 const TypeX* t = phase->type(in(2))->isa_intptr_t();
2747 if (!t) return NULL;
2748 if (!t->is_con()) return NULL;
2749 intptr_t raw_count = t->get_con();
2750 intptr_t size = raw_count;
2751 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
2752 // Clearing nothing uses the Identity call.
2753 // Negative clears are possible on dead ClearArrays
2754 // (see jck test stmt114.stmt11402.val).
2755 if (size <= 0 || size % unit != 0) return NULL;
2756 intptr_t count = size / unit;
2757 // Length too long; communicate this to matchers and assemblers.
2758 // Assemblers are responsible to produce fast hardware clears for it.
2759 if (size > InitArrayShortSize) {
2760 return new ClearArrayNode(in(0), in(1), in(2), in(3), true);
2761 }
2762 Node *mem = in(1);
2763 if( phase->type(mem)==Type::TOP ) return NULL;
2764 Node *adr = in(3);
2765 const Type* at = phase->type(adr);
2766 if( at==Type::TOP ) return NULL;
2767 const TypePtr* atp = at->isa_ptr();
2768 // adjust atp to be the correct array element address type
2769 if (atp == NULL) atp = TypePtr::BOTTOM;
2770 else atp = atp->add_offset(Type::OffsetBot);
2771 // Get base for derived pointer purposes
2772 if( adr->Opcode() != Op_AddP ) Unimplemented();
2773 Node *base = adr->in(1);
2774
2775 Node *zero = phase->makecon(TypeLong::ZERO);
2776 Node *off = phase->MakeConX(BytesPerLong);
2777 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
2778 count--;
2779 while( count-- ) {
2780 mem = phase->transform(mem);
2781 adr = phase->transform(new AddPNode(base,adr,off));
2782 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
2783 }
2784 return mem;
2785 }
2786
2787 //----------------------------step_through----------------------------------
2788 // Return allocation input memory edge if it is different instance
2789 // or itself if it is the one we are looking for.
2790 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) {
2791 Node* n = *np;
2792 assert(n->is_ClearArray(), "sanity");
2793 intptr_t offset;
2794 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
2795 // This method is called only before Allocate nodes are expanded
2796 // during macro nodes expansion. Before that ClearArray nodes are
2797 // only generated in PhaseMacroExpand::generate_arraycopy() (before
2798 // Allocate nodes are expanded) which follows allocations.
2799 assert(alloc != NULL, "should have allocation");
2800 if (alloc->_idx == instance_id) {
2801 // Can not bypass initialization of the instance we are looking for.
2802 return false;
2803 }
2804 // Otherwise skip it.
2805 InitializeNode* init = alloc->initialization();
2806 if (init != NULL)
2807 *np = init->in(TypeFunc::Memory);
2808 else
2809 *np = alloc->in(TypeFunc::Memory);
2810 return true;
2811 }
2812
2813 //----------------------------clear_memory-------------------------------------
2814 // Generate code to initialize object storage to zero.
2815 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2816 intptr_t start_offset,
2817 Node* end_offset,
2818 PhaseGVN* phase) {
2819 intptr_t offset = start_offset;
2820
2821 int unit = BytesPerLong;
2822 if ((offset % unit) != 0) {
2823 Node* adr = new AddPNode(dest, dest, phase->MakeConX(offset));
2824 adr = phase->transform(adr);
2825 const TypePtr* atp = TypeRawPtr::BOTTOM;
2826 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
2827 mem = phase->transform(mem);
2828 offset += BytesPerInt;
2829 }
2830 assert((offset % unit) == 0, "");
2831
2832 // Initialize the remaining stuff, if any, with a ClearArray.
2833 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase);
2834 }
2835
2836 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2837 Node* start_offset,
2838 Node* end_offset,
2839 PhaseGVN* phase) {
2840 if (start_offset == end_offset) {
2841 // nothing to do
2842 return mem;
2843 }
2844
2845 int unit = BytesPerLong;
2846 Node* zbase = start_offset;
2847 Node* zend = end_offset;
2848
2849 // Scale to the unit required by the CPU:
2850 if (!Matcher::init_array_count_is_in_bytes) {
2851 Node* shift = phase->intcon(exact_log2(unit));
2852 zbase = phase->transform(new URShiftXNode(zbase, shift) );
2853 zend = phase->transform(new URShiftXNode(zend, shift) );
2854 }
2855
2856 // Bulk clear double-words
2857 Node* zsize = phase->transform(new SubXNode(zend, zbase) );
2858 Node* adr = phase->transform(new AddPNode(dest, dest, start_offset) );
2859 mem = new ClearArrayNode(ctl, mem, zsize, adr, false);
2860 return phase->transform(mem);
2861 }
2862
2863 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2864 intptr_t start_offset,
2865 intptr_t end_offset,
2866 PhaseGVN* phase) {
2867 if (start_offset == end_offset) {
2868 // nothing to do
2869 return mem;
2870 }
2871
2872 assert((end_offset % BytesPerInt) == 0, "odd end offset");
2873 intptr_t done_offset = end_offset;
2874 if ((done_offset % BytesPerLong) != 0) {
2875 done_offset -= BytesPerInt;
2876 }
2877 if (done_offset > start_offset) {
2878 mem = clear_memory(ctl, mem, dest,
2879 start_offset, phase->MakeConX(done_offset), phase);
2880 }
2881 if (done_offset < end_offset) { // emit the final 32-bit store
2882 Node* adr = new AddPNode(dest, dest, phase->MakeConX(done_offset));
2883 adr = phase->transform(adr);
2884 const TypePtr* atp = TypeRawPtr::BOTTOM;
2885 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
2886 mem = phase->transform(mem);
2887 done_offset += BytesPerInt;
2888 }
2889 assert(done_offset == end_offset, "");
2890 return mem;
2891 }
2892
2893 //=============================================================================
2894 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
2895 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)),
2896 _adr_type(C->get_adr_type(alias_idx))
2897 {
2898 init_class_id(Class_MemBar);
2899 Node* top = C->top();
2900 init_req(TypeFunc::I_O,top);
2901 init_req(TypeFunc::FramePtr,top);
2902 init_req(TypeFunc::ReturnAdr,top);
2903 if (precedent != NULL)
2904 init_req(TypeFunc::Parms, precedent);
2905 }
2906
2907 //------------------------------cmp--------------------------------------------
2908 uint MemBarNode::hash() const { return NO_HASH; }
2909 uint MemBarNode::cmp( const Node &n ) const {
2910 return (&n == this); // Always fail except on self
2911 }
2912
2913 //------------------------------make-------------------------------------------
2914 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
2915 switch (opcode) {
2916 case Op_MemBarAcquire: return new MemBarAcquireNode(C, atp, pn);
2917 case Op_LoadFence: return new LoadFenceNode(C, atp, pn);
2918 case Op_MemBarRelease: return new MemBarReleaseNode(C, atp, pn);
2919 case Op_StoreFence: return new StoreFenceNode(C, atp, pn);
2920 case Op_MemBarAcquireLock: return new MemBarAcquireLockNode(C, atp, pn);
2921 case Op_MemBarReleaseLock: return new MemBarReleaseLockNode(C, atp, pn);
2922 case Op_MemBarVolatile: return new MemBarVolatileNode(C, atp, pn);
2923 case Op_MemBarCPUOrder: return new MemBarCPUOrderNode(C, atp, pn);
2924 case Op_OnSpinWait: return new OnSpinWaitNode(C, atp, pn);
2925 case Op_Initialize: return new InitializeNode(C, atp, pn);
2926 case Op_MemBarStoreStore: return new MemBarStoreStoreNode(C, atp, pn);
2927 default: ShouldNotReachHere(); return NULL;
2928 }
2929 }
2930
2931 //------------------------------Ideal------------------------------------------
2932 // Return a node which is more "ideal" than the current node. Strip out
2933 // control copies
2934 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2935 if (remove_dead_region(phase, can_reshape)) return this;
2936 // Don't bother trying to transform a dead node
2937 if (in(0) && in(0)->is_top()) {
2938 return NULL;
2939 }
2940
2941 bool progress = false;
2942 // Eliminate volatile MemBars for scalar replaced objects.
2943 if (can_reshape && req() == (Precedent+1)) {
2944 bool eliminate = false;
2945 int opc = Opcode();
2946 if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) {
2947 // Volatile field loads and stores.
2948 Node* my_mem = in(MemBarNode::Precedent);
2949 // The MembarAquire may keep an unused LoadNode alive through the Precedent edge
2950 if ((my_mem != NULL) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) {
2951 // if the Precedent is a decodeN and its input (a Load) is used at more than one place,
2952 // replace this Precedent (decodeN) with the Load instead.
2953 if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1)) {
2954 Node* load_node = my_mem->in(1);
2955 set_req(MemBarNode::Precedent, load_node);
2956 phase->is_IterGVN()->_worklist.push(my_mem);
2957 my_mem = load_node;
2958 } else {
2959 assert(my_mem->unique_out() == this, "sanity");
2960 del_req(Precedent);
2961 phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later
2962 my_mem = NULL;
2963 }
2964 progress = true;
2965 }
2966 if (my_mem != NULL && my_mem->is_Mem()) {
2967 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
2968 // Check for scalar replaced object reference.
2969 if( t_oop != NULL && t_oop->is_known_instance_field() &&
2970 t_oop->offset() != Type::OffsetBot &&
2971 t_oop->offset() != Type::OffsetTop) {
2972 eliminate = true;
2973 }
2974 }
2975 } else if (opc == Op_MemBarRelease) {
2976 // Final field stores.
2977 Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent), phase);
2978 if ((alloc != NULL) && alloc->is_Allocate() &&
2979 alloc->as_Allocate()->does_not_escape_thread()) {
2980 // The allocated object does not escape.
2981 eliminate = true;
2982 }
2983 }
2984 if (eliminate) {
2985 // Replace MemBar projections by its inputs.
2986 PhaseIterGVN* igvn = phase->is_IterGVN();
2987 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
2988 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
2989 // Must return either the original node (now dead) or a new node
2990 // (Do not return a top here, since that would break the uniqueness of top.)
2991 return new ConINode(TypeInt::ZERO);
2992 }
2993 }
2994 return progress ? this : NULL;
2995 }
2996
2997 //------------------------------Value------------------------------------------
2998 const Type* MemBarNode::Value(PhaseGVN* phase) const {
2999 if( !in(0) ) return Type::TOP;
3000 if( phase->type(in(0)) == Type::TOP )
3001 return Type::TOP;
3002 return TypeTuple::MEMBAR;
3003 }
3004
3005 //------------------------------match------------------------------------------
3006 // Construct projections for memory.
3007 Node *MemBarNode::match(const ProjNode *proj, const Matcher *m, const RegMask* mask) {
3008 switch (proj->_con) {
3009 case TypeFunc::Control:
3010 case TypeFunc::Memory:
3011 return new MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
3012 }
3013 ShouldNotReachHere();
3014 return NULL;
3015 }
3016
3017 //===========================InitializeNode====================================
3018 // SUMMARY:
3019 // This node acts as a memory barrier on raw memory, after some raw stores.
3020 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
3021 // The Initialize can 'capture' suitably constrained stores as raw inits.
3022 // It can coalesce related raw stores into larger units (called 'tiles').
3023 // It can avoid zeroing new storage for memory units which have raw inits.
3024 // At macro-expansion, it is marked 'complete', and does not optimize further.
3025 //
3026 // EXAMPLE:
3027 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
3028 // ctl = incoming control; mem* = incoming memory
3029 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
3030 // First allocate uninitialized memory and fill in the header:
3031 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
3032 // ctl := alloc.Control; mem* := alloc.Memory*
3033 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
3034 // Then initialize to zero the non-header parts of the raw memory block:
3035 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
3036 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
3037 // After the initialize node executes, the object is ready for service:
3038 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
3039 // Suppose its body is immediately initialized as {1,2}:
3040 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3041 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3042 // mem.SLICE(#short[*]) := store2
3043 //
3044 // DETAILS:
3045 // An InitializeNode collects and isolates object initialization after
3046 // an AllocateNode and before the next possible safepoint. As a
3047 // memory barrier (MemBarNode), it keeps critical stores from drifting
3048 // down past any safepoint or any publication of the allocation.
3049 // Before this barrier, a newly-allocated object may have uninitialized bits.
3050 // After this barrier, it may be treated as a real oop, and GC is allowed.
3051 //
3052 // The semantics of the InitializeNode include an implicit zeroing of
3053 // the new object from object header to the end of the object.
3054 // (The object header and end are determined by the AllocateNode.)
3055 //
3056 // Certain stores may be added as direct inputs to the InitializeNode.
3057 // These stores must update raw memory, and they must be to addresses
3058 // derived from the raw address produced by AllocateNode, and with
3059 // a constant offset. They must be ordered by increasing offset.
3060 // The first one is at in(RawStores), the last at in(req()-1).
3061 // Unlike most memory operations, they are not linked in a chain,
3062 // but are displayed in parallel as users of the rawmem output of
3063 // the allocation.
3064 //
3065 // (See comments in InitializeNode::capture_store, which continue
3066 // the example given above.)
3067 //
3068 // When the associated Allocate is macro-expanded, the InitializeNode
3069 // may be rewritten to optimize collected stores. A ClearArrayNode
3070 // may also be created at that point to represent any required zeroing.
3071 // The InitializeNode is then marked 'complete', prohibiting further
3072 // capturing of nearby memory operations.
3073 //
3074 // During macro-expansion, all captured initializations which store
3075 // constant values of 32 bits or smaller are coalesced (if advantageous)
3076 // into larger 'tiles' 32 or 64 bits. This allows an object to be
3077 // initialized in fewer memory operations. Memory words which are
3078 // covered by neither tiles nor non-constant stores are pre-zeroed
3079 // by explicit stores of zero. (The code shape happens to do all
3080 // zeroing first, then all other stores, with both sequences occurring
3081 // in order of ascending offsets.)
3082 //
3083 // Alternatively, code may be inserted between an AllocateNode and its
3084 // InitializeNode, to perform arbitrary initialization of the new object.
3085 // E.g., the object copying intrinsics insert complex data transfers here.
3086 // The initialization must then be marked as 'complete' disable the
3087 // built-in zeroing semantics and the collection of initializing stores.
3088 //
3089 // While an InitializeNode is incomplete, reads from the memory state
3090 // produced by it are optimizable if they match the control edge and
3091 // new oop address associated with the allocation/initialization.
3092 // They return a stored value (if the offset matches) or else zero.
3093 // A write to the memory state, if it matches control and address,
3094 // and if it is to a constant offset, may be 'captured' by the
3095 // InitializeNode. It is cloned as a raw memory operation and rewired
3096 // inside the initialization, to the raw oop produced by the allocation.
3097 // Operations on addresses which are provably distinct (e.g., to
3098 // other AllocateNodes) are allowed to bypass the initialization.
3099 //
3100 // The effect of all this is to consolidate object initialization
3101 // (both arrays and non-arrays, both piecewise and bulk) into a
3102 // single location, where it can be optimized as a unit.
3103 //
3104 // Only stores with an offset less than TrackedInitializationLimit words
3105 // will be considered for capture by an InitializeNode. This puts a
3106 // reasonable limit on the complexity of optimized initializations.
3107
3108 //---------------------------InitializeNode------------------------------------
3109 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
3110 : _is_complete(Incomplete), _does_not_escape(false),
3111 MemBarNode(C, adr_type, rawoop)
3112 {
3113 init_class_id(Class_Initialize);
3114
3115 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
3116 assert(in(RawAddress) == rawoop, "proper init");
3117 // Note: allocation() can be NULL, for secondary initialization barriers
3118 }
3119
3120 // Since this node is not matched, it will be processed by the
3121 // register allocator. Declare that there are no constraints
3122 // on the allocation of the RawAddress edge.
3123 const RegMask &InitializeNode::in_RegMask(uint idx) const {
3124 // This edge should be set to top, by the set_complete. But be conservative.
3125 if (idx == InitializeNode::RawAddress)
3126 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
3127 return RegMask::Empty;
3128 }
3129
3130 Node* InitializeNode::memory(uint alias_idx) {
3131 Node* mem = in(Memory);
3132 if (mem->is_MergeMem()) {
3133 return mem->as_MergeMem()->memory_at(alias_idx);
3134 } else {
3135 // incoming raw memory is not split
3136 return mem;
3137 }
3138 }
3139
3140 bool InitializeNode::is_non_zero() {
3141 if (is_complete()) return false;
3142 remove_extra_zeroes();
3143 return (req() > RawStores);
3144 }
3145
3146 void InitializeNode::set_complete(PhaseGVN* phase) {
3147 assert(!is_complete(), "caller responsibility");
3148 _is_complete = Complete;
3149
3150 // After this node is complete, it contains a bunch of
3151 // raw-memory initializations. There is no need for
3152 // it to have anything to do with non-raw memory effects.
3153 // Therefore, tell all non-raw users to re-optimize themselves,
3154 // after skipping the memory effects of this initialization.
3155 PhaseIterGVN* igvn = phase->is_IterGVN();
3156 if (igvn) igvn->add_users_to_worklist(this);
3157 }
3158
3159 // convenience function
3160 // return false if the init contains any stores already
3161 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
3162 InitializeNode* init = initialization();
3163 if (init == NULL || init->is_complete()) return false;
3164 init->remove_extra_zeroes();
3165 // for now, if this allocation has already collected any inits, bail:
3166 if (init->is_non_zero()) return false;
3167 init->set_complete(phase);
3168 return true;
3169 }
3170
3171 void InitializeNode::remove_extra_zeroes() {
3172 if (req() == RawStores) return;
3173 Node* zmem = zero_memory();
3174 uint fill = RawStores;
3175 for (uint i = fill; i < req(); i++) {
3176 Node* n = in(i);
3177 if (n->is_top() || n == zmem) continue; // skip
3178 if (fill < i) set_req(fill, n); // compact
3179 ++fill;
3180 }
3181 // delete any empty spaces created:
3182 while (fill < req()) {
3183 del_req(fill);
3184 }
3185 }
3186
3187 // Helper for remembering which stores go with which offsets.
3188 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) {
3189 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
3190 intptr_t offset = -1;
3191 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
3192 phase, offset);
3193 if (base == NULL) return -1; // something is dead,
3194 if (offset < 0) return -1; // dead, dead
3195 return offset;
3196 }
3197
3198 // Helper for proving that an initialization expression is
3199 // "simple enough" to be folded into an object initialization.
3200 // Attempts to prove that a store's initial value 'n' can be captured
3201 // within the initialization without creating a vicious cycle, such as:
3202 // { Foo p = new Foo(); p.next = p; }
3203 // True for constants and parameters and small combinations thereof.
3204 bool InitializeNode::detect_init_independence(Node* n, int& count) {
3205 if (n == NULL) return true; // (can this really happen?)
3206 if (n->is_Proj()) n = n->in(0);
3207 if (n == this) return false; // found a cycle
3208 if (n->is_Con()) return true;
3209 if (n->is_Start()) return true; // params, etc., are OK
3210 if (n->is_Root()) return true; // even better
3211
3212 Node* ctl = n->in(0);
3213 if (ctl != NULL && !ctl->is_top()) {
3214 if (ctl->is_Proj()) ctl = ctl->in(0);
3215 if (ctl == this) return false;
3216
3217 // If we already know that the enclosing memory op is pinned right after
3218 // the init, then any control flow that the store has picked up
3219 // must have preceded the init, or else be equal to the init.
3220 // Even after loop optimizations (which might change control edges)
3221 // a store is never pinned *before* the availability of its inputs.
3222 if (!MemNode::all_controls_dominate(n, this))
3223 return false; // failed to prove a good control
3224 }
3225
3226 // Check data edges for possible dependencies on 'this'.
3227 if ((count += 1) > 20) return false; // complexity limit
3228 for (uint i = 1; i < n->req(); i++) {
3229 Node* m = n->in(i);
3230 if (m == NULL || m == n || m->is_top()) continue;
3231 uint first_i = n->find_edge(m);
3232 if (i != first_i) continue; // process duplicate edge just once
3233 if (!detect_init_independence(m, count)) {
3234 return false;
3235 }
3236 }
3237
3238 return true;
3239 }
3240
3241 // Here are all the checks a Store must pass before it can be moved into
3242 // an initialization. Returns zero if a check fails.
3243 // On success, returns the (constant) offset to which the store applies,
3244 // within the initialized memory.
3245 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase, bool can_reshape) {
3246 const int FAIL = 0;
3247 if (st->is_unaligned_access()) {
3248 return FAIL;
3249 }
3250 if (st->req() != MemNode::ValueIn + 1)
3251 return FAIL; // an inscrutable StoreNode (card mark?)
3252 Node* ctl = st->in(MemNode::Control);
3253 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this))
3254 return FAIL; // must be unconditional after the initialization
3255 Node* mem = st->in(MemNode::Memory);
3256 if (!(mem->is_Proj() && mem->in(0) == this))
3257 return FAIL; // must not be preceded by other stores
3258 Node* adr = st->in(MemNode::Address);
3259 intptr_t offset;
3260 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
3261 if (alloc == NULL)
3262 return FAIL; // inscrutable address
3263 if (alloc != allocation())
3264 return FAIL; // wrong allocation! (store needs to float up)
3265 Node* val = st->in(MemNode::ValueIn);
3266 int complexity_count = 0;
3267 if (!detect_init_independence(val, complexity_count))
3268 return FAIL; // stored value must be 'simple enough'
3269
3270 // The Store can be captured only if nothing after the allocation
3271 // and before the Store is using the memory location that the store
3272 // overwrites.
3273 bool failed = false;
3274 // If is_complete_with_arraycopy() is true the shape of the graph is
3275 // well defined and is safe so no need for extra checks.
3276 if (!is_complete_with_arraycopy()) {
3277 // We are going to look at each use of the memory state following
3278 // the allocation to make sure nothing reads the memory that the
3279 // Store writes.
3280 const TypePtr* t_adr = phase->type(adr)->isa_ptr();
3281 int alias_idx = phase->C->get_alias_index(t_adr);
3282 ResourceMark rm;
3283 Unique_Node_List mems;
3284 mems.push(mem);
3285 Node* unique_merge = NULL;
3286 for (uint next = 0; next < mems.size(); ++next) {
3287 Node *m = mems.at(next);
3288 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
3289 Node *n = m->fast_out(j);
3290 if (n->outcnt() == 0) {
3291 continue;
3292 }
3293 if (n == st) {
3294 continue;
3295 } else if (n->in(0) != NULL && n->in(0) != ctl) {
3296 // If the control of this use is different from the control
3297 // of the Store which is right after the InitializeNode then
3298 // this node cannot be between the InitializeNode and the
3299 // Store.
3300 continue;
3301 } else if (n->is_MergeMem()) {
3302 if (n->as_MergeMem()->memory_at(alias_idx) == m) {
3303 // We can hit a MergeMemNode (that will likely go away
3304 // later) that is a direct use of the memory state
3305 // following the InitializeNode on the same slice as the
3306 // store node that we'd like to capture. We need to check
3307 // the uses of the MergeMemNode.
3308 mems.push(n);
3309 }
3310 } else if (n->is_Mem()) {
3311 Node* other_adr = n->in(MemNode::Address);
3312 if (other_adr == adr) {
3313 failed = true;
3314 break;
3315 } else {
3316 const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr();
3317 if (other_t_adr != NULL) {
3318 int other_alias_idx = phase->C->get_alias_index(other_t_adr);
3319 if (other_alias_idx == alias_idx) {
3320 // A load from the same memory slice as the store right
3321 // after the InitializeNode. We check the control of the
3322 // object/array that is loaded from. If it's the same as
3323 // the store control then we cannot capture the store.
3324 assert(!n->is_Store(), "2 stores to same slice on same control?");
3325 Node* base = other_adr;
3326 assert(base->is_AddP(), "should be addp but is %s", base->Name());
3327 base = base->in(AddPNode::Base);
3328 if (base != NULL) {
3329 base = base->uncast();
3330 if (base->is_Proj() && base->in(0) == alloc) {
3331 failed = true;
3332 break;
3333 }
3334 }
3335 }
3336 }
3337 }
3338 } else {
3339 failed = true;
3340 break;
3341 }
3342 }
3343 }
3344 }
3345 if (failed) {
3346 if (!can_reshape) {
3347 // We decided we couldn't capture the store during parsing. We
3348 // should try again during the next IGVN once the graph is
3349 // cleaner.
3350 phase->C->record_for_igvn(st);
3351 }
3352 return FAIL;
3353 }
3354
3355 return offset; // success
3356 }
3357
3358 // Find the captured store in(i) which corresponds to the range
3359 // [start..start+size) in the initialized object.
3360 // If there is one, return its index i. If there isn't, return the
3361 // negative of the index where it should be inserted.
3362 // Return 0 if the queried range overlaps an initialization boundary
3363 // or if dead code is encountered.
3364 // If size_in_bytes is zero, do not bother with overlap checks.
3365 int InitializeNode::captured_store_insertion_point(intptr_t start,
3366 int size_in_bytes,
3367 PhaseTransform* phase) {
3368 const int FAIL = 0, MAX_STORE = BytesPerLong;
3369
3370 if (is_complete())
3371 return FAIL; // arraycopy got here first; punt
3372
3373 assert(allocation() != NULL, "must be present");
3374
3375 // no negatives, no header fields:
3376 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
3377
3378 // after a certain size, we bail out on tracking all the stores:
3379 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3380 if (start >= ti_limit) return FAIL;
3381
3382 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
3383 if (i >= limit) return -(int)i; // not found; here is where to put it
3384
3385 Node* st = in(i);
3386 intptr_t st_off = get_store_offset(st, phase);
3387 if (st_off < 0) {
3388 if (st != zero_memory()) {
3389 return FAIL; // bail out if there is dead garbage
3390 }
3391 } else if (st_off > start) {
3392 // ...we are done, since stores are ordered
3393 if (st_off < start + size_in_bytes) {
3394 return FAIL; // the next store overlaps
3395 }
3396 return -(int)i; // not found; here is where to put it
3397 } else if (st_off < start) {
3398 if (size_in_bytes != 0 &&
3399 start < st_off + MAX_STORE &&
3400 start < st_off + st->as_Store()->memory_size()) {
3401 return FAIL; // the previous store overlaps
3402 }
3403 } else {
3404 if (size_in_bytes != 0 &&
3405 st->as_Store()->memory_size() != size_in_bytes) {
3406 return FAIL; // mismatched store size
3407 }
3408 return i;
3409 }
3410
3411 ++i;
3412 }
3413 }
3414
3415 // Look for a captured store which initializes at the offset 'start'
3416 // with the given size. If there is no such store, and no other
3417 // initialization interferes, then return zero_memory (the memory
3418 // projection of the AllocateNode).
3419 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
3420 PhaseTransform* phase) {
3421 assert(stores_are_sane(phase), "");
3422 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3423 if (i == 0) {
3424 return NULL; // something is dead
3425 } else if (i < 0) {
3426 return zero_memory(); // just primordial zero bits here
3427 } else {
3428 Node* st = in(i); // here is the store at this position
3429 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
3430 return st;
3431 }
3432 }
3433
3434 // Create, as a raw pointer, an address within my new object at 'offset'.
3435 Node* InitializeNode::make_raw_address(intptr_t offset,
3436 PhaseTransform* phase) {
3437 Node* addr = in(RawAddress);
3438 if (offset != 0) {
3439 Compile* C = phase->C;
3440 addr = phase->transform( new AddPNode(C->top(), addr,
3441 phase->MakeConX(offset)) );
3442 }
3443 return addr;
3444 }
3445
3446 // Clone the given store, converting it into a raw store
3447 // initializing a field or element of my new object.
3448 // Caller is responsible for retiring the original store,
3449 // with subsume_node or the like.
3450 //
3451 // From the example above InitializeNode::InitializeNode,
3452 // here are the old stores to be captured:
3453 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3454 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3455 //
3456 // Here is the changed code; note the extra edges on init:
3457 // alloc = (Allocate ...)
3458 // rawoop = alloc.RawAddress
3459 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
3460 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
3461 // init = (Initialize alloc.Control alloc.Memory rawoop
3462 // rawstore1 rawstore2)
3463 //
3464 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
3465 PhaseTransform* phase, bool can_reshape) {
3466 assert(stores_are_sane(phase), "");
3467
3468 if (start < 0) return NULL;
3469 assert(can_capture_store(st, phase, can_reshape) == start, "sanity");
3470
3471 Compile* C = phase->C;
3472 int size_in_bytes = st->memory_size();
3473 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3474 if (i == 0) return NULL; // bail out
3475 Node* prev_mem = NULL; // raw memory for the captured store
3476 if (i > 0) {
3477 prev_mem = in(i); // there is a pre-existing store under this one
3478 set_req(i, C->top()); // temporarily disconnect it
3479 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
3480 } else {
3481 i = -i; // no pre-existing store
3482 prev_mem = zero_memory(); // a slice of the newly allocated object
3483 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
3484 set_req(--i, C->top()); // reuse this edge; it has been folded away
3485 else
3486 ins_req(i, C->top()); // build a new edge
3487 }
3488 Node* new_st = st->clone();
3489 new_st->set_req(MemNode::Control, in(Control));
3490 new_st->set_req(MemNode::Memory, prev_mem);
3491 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
3492 new_st = phase->transform(new_st);
3493
3494 // At this point, new_st might have swallowed a pre-existing store
3495 // at the same offset, or perhaps new_st might have disappeared,
3496 // if it redundantly stored the same value (or zero to fresh memory).
3497
3498 // In any case, wire it in:
3499 phase->igvn_rehash_node_delayed(this);
3500 set_req(i, new_st);
3501
3502 // The caller may now kill the old guy.
3503 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
3504 assert(check_st == new_st || check_st == NULL, "must be findable");
3505 assert(!is_complete(), "");
3506 return new_st;
3507 }
3508
3509 static bool store_constant(jlong* tiles, int num_tiles,
3510 intptr_t st_off, int st_size,
3511 jlong con) {
3512 if ((st_off & (st_size-1)) != 0)
3513 return false; // strange store offset (assume size==2**N)
3514 address addr = (address)tiles + st_off;
3515 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
3516 switch (st_size) {
3517 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
3518 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
3519 case sizeof(jint): *(jint*) addr = (jint) con; break;
3520 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
3521 default: return false; // strange store size (detect size!=2**N here)
3522 }
3523 return true; // return success to caller
3524 }
3525
3526 // Coalesce subword constants into int constants and possibly
3527 // into long constants. The goal, if the CPU permits,
3528 // is to initialize the object with a small number of 64-bit tiles.
3529 // Also, convert floating-point constants to bit patterns.
3530 // Non-constants are not relevant to this pass.
3531 //
3532 // In terms of the running example on InitializeNode::InitializeNode
3533 // and InitializeNode::capture_store, here is the transformation
3534 // of rawstore1 and rawstore2 into rawstore12:
3535 // alloc = (Allocate ...)
3536 // rawoop = alloc.RawAddress
3537 // tile12 = 0x00010002
3538 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
3539 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
3540 //
3541 void
3542 InitializeNode::coalesce_subword_stores(intptr_t header_size,
3543 Node* size_in_bytes,
3544 PhaseGVN* phase) {
3545 Compile* C = phase->C;
3546
3547 assert(stores_are_sane(phase), "");
3548 // Note: After this pass, they are not completely sane,
3549 // since there may be some overlaps.
3550
3551 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
3552
3553 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3554 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
3555 size_limit = MIN2(size_limit, ti_limit);
3556 size_limit = align_size_up(size_limit, BytesPerLong);
3557 int num_tiles = size_limit / BytesPerLong;
3558
3559 // allocate space for the tile map:
3560 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
3561 jlong tiles_buf[small_len];
3562 Node* nodes_buf[small_len];
3563 jlong inits_buf[small_len];
3564 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
3565 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3566 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
3567 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
3568 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
3569 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3570 // tiles: exact bitwise model of all primitive constants
3571 // nodes: last constant-storing node subsumed into the tiles model
3572 // inits: which bytes (in each tile) are touched by any initializations
3573
3574 //// Pass A: Fill in the tile model with any relevant stores.
3575
3576 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
3577 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
3578 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
3579 Node* zmem = zero_memory(); // initially zero memory state
3580 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3581 Node* st = in(i);
3582 intptr_t st_off = get_store_offset(st, phase);
3583
3584 // Figure out the store's offset and constant value:
3585 if (st_off < header_size) continue; //skip (ignore header)
3586 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
3587 int st_size = st->as_Store()->memory_size();
3588 if (st_off + st_size > size_limit) break;
3589
3590 // Record which bytes are touched, whether by constant or not.
3591 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
3592 continue; // skip (strange store size)
3593
3594 const Type* val = phase->type(st->in(MemNode::ValueIn));
3595 if (!val->singleton()) continue; //skip (non-con store)
3596 BasicType type = val->basic_type();
3597
3598 jlong con = 0;
3599 switch (type) {
3600 case T_INT: con = val->is_int()->get_con(); break;
3601 case T_LONG: con = val->is_long()->get_con(); break;
3602 case T_FLOAT: con = jint_cast(val->getf()); break;
3603 case T_DOUBLE: con = jlong_cast(val->getd()); break;
3604 default: continue; //skip (odd store type)
3605 }
3606
3607 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
3608 st->Opcode() == Op_StoreL) {
3609 continue; // This StoreL is already optimal.
3610 }
3611
3612 // Store down the constant.
3613 store_constant(tiles, num_tiles, st_off, st_size, con);
3614
3615 intptr_t j = st_off >> LogBytesPerLong;
3616
3617 if (type == T_INT && st_size == BytesPerInt
3618 && (st_off & BytesPerInt) == BytesPerInt) {
3619 jlong lcon = tiles[j];
3620 if (!Matcher::isSimpleConstant64(lcon) &&
3621 st->Opcode() == Op_StoreI) {
3622 // This StoreI is already optimal by itself.
3623 jint* intcon = (jint*) &tiles[j];
3624 intcon[1] = 0; // undo the store_constant()
3625
3626 // If the previous store is also optimal by itself, back up and
3627 // undo the action of the previous loop iteration... if we can.
3628 // But if we can't, just let the previous half take care of itself.
3629 st = nodes[j];
3630 st_off -= BytesPerInt;
3631 con = intcon[0];
3632 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) {
3633 assert(st_off >= header_size, "still ignoring header");
3634 assert(get_store_offset(st, phase) == st_off, "must be");
3635 assert(in(i-1) == zmem, "must be");
3636 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
3637 assert(con == tcon->is_int()->get_con(), "must be");
3638 // Undo the effects of the previous loop trip, which swallowed st:
3639 intcon[0] = 0; // undo store_constant()
3640 set_req(i-1, st); // undo set_req(i, zmem)
3641 nodes[j] = NULL; // undo nodes[j] = st
3642 --old_subword; // undo ++old_subword
3643 }
3644 continue; // This StoreI is already optimal.
3645 }
3646 }
3647
3648 // This store is not needed.
3649 set_req(i, zmem);
3650 nodes[j] = st; // record for the moment
3651 if (st_size < BytesPerLong) // something has changed
3652 ++old_subword; // includes int/float, but who's counting...
3653 else ++old_long;
3654 }
3655
3656 if ((old_subword + old_long) == 0)
3657 return; // nothing more to do
3658
3659 //// Pass B: Convert any non-zero tiles into optimal constant stores.
3660 // Be sure to insert them before overlapping non-constant stores.
3661 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
3662 for (int j = 0; j < num_tiles; j++) {
3663 jlong con = tiles[j];
3664 jlong init = inits[j];
3665 if (con == 0) continue;
3666 jint con0, con1; // split the constant, address-wise
3667 jint init0, init1; // split the init map, address-wise
3668 { union { jlong con; jint intcon[2]; } u;
3669 u.con = con;
3670 con0 = u.intcon[0];
3671 con1 = u.intcon[1];
3672 u.con = init;
3673 init0 = u.intcon[0];
3674 init1 = u.intcon[1];
3675 }
3676
3677 Node* old = nodes[j];
3678 assert(old != NULL, "need the prior store");
3679 intptr_t offset = (j * BytesPerLong);
3680
3681 bool split = !Matcher::isSimpleConstant64(con);
3682
3683 if (offset < header_size) {
3684 assert(offset + BytesPerInt >= header_size, "second int counts");
3685 assert(*(jint*)&tiles[j] == 0, "junk in header");
3686 split = true; // only the second word counts
3687 // Example: int a[] = { 42 ... }
3688 } else if (con0 == 0 && init0 == -1) {
3689 split = true; // first word is covered by full inits
3690 // Example: int a[] = { ... foo(), 42 ... }
3691 } else if (con1 == 0 && init1 == -1) {
3692 split = true; // second word is covered by full inits
3693 // Example: int a[] = { ... 42, foo() ... }
3694 }
3695
3696 // Here's a case where init0 is neither 0 nor -1:
3697 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
3698 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
3699 // In this case the tile is not split; it is (jlong)42.
3700 // The big tile is stored down, and then the foo() value is inserted.
3701 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
3702
3703 Node* ctl = old->in(MemNode::Control);
3704 Node* adr = make_raw_address(offset, phase);
3705 const TypePtr* atp = TypeRawPtr::BOTTOM;
3706
3707 // One or two coalesced stores to plop down.
3708 Node* st[2];
3709 intptr_t off[2];
3710 int nst = 0;
3711 if (!split) {
3712 ++new_long;
3713 off[nst] = offset;
3714 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3715 phase->longcon(con), T_LONG, MemNode::unordered);
3716 } else {
3717 // Omit either if it is a zero.
3718 if (con0 != 0) {
3719 ++new_int;
3720 off[nst] = offset;
3721 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3722 phase->intcon(con0), T_INT, MemNode::unordered);
3723 }
3724 if (con1 != 0) {
3725 ++new_int;
3726 offset += BytesPerInt;
3727 adr = make_raw_address(offset, phase);
3728 off[nst] = offset;
3729 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3730 phase->intcon(con1), T_INT, MemNode::unordered);
3731 }
3732 }
3733
3734 // Insert second store first, then the first before the second.
3735 // Insert each one just before any overlapping non-constant stores.
3736 while (nst > 0) {
3737 Node* st1 = st[--nst];
3738 C->copy_node_notes_to(st1, old);
3739 st1 = phase->transform(st1);
3740 offset = off[nst];
3741 assert(offset >= header_size, "do not smash header");
3742 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
3743 guarantee(ins_idx != 0, "must re-insert constant store");
3744 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
3745 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
3746 set_req(--ins_idx, st1);
3747 else
3748 ins_req(ins_idx, st1);
3749 }
3750 }
3751
3752 if (PrintCompilation && WizardMode)
3753 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
3754 old_subword, old_long, new_int, new_long);
3755 if (C->log() != NULL)
3756 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
3757 old_subword, old_long, new_int, new_long);
3758
3759 // Clean up any remaining occurrences of zmem:
3760 remove_extra_zeroes();
3761 }
3762
3763 // Explore forward from in(start) to find the first fully initialized
3764 // word, and return its offset. Skip groups of subword stores which
3765 // together initialize full words. If in(start) is itself part of a
3766 // fully initialized word, return the offset of in(start). If there
3767 // are no following full-word stores, or if something is fishy, return
3768 // a negative value.
3769 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
3770 int int_map = 0;
3771 intptr_t int_map_off = 0;
3772 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
3773
3774 for (uint i = start, limit = req(); i < limit; i++) {
3775 Node* st = in(i);
3776
3777 intptr_t st_off = get_store_offset(st, phase);
3778 if (st_off < 0) break; // return conservative answer
3779
3780 int st_size = st->as_Store()->memory_size();
3781 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
3782 return st_off; // we found a complete word init
3783 }
3784
3785 // update the map:
3786
3787 intptr_t this_int_off = align_size_down(st_off, BytesPerInt);
3788 if (this_int_off != int_map_off) {
3789 // reset the map:
3790 int_map = 0;
3791 int_map_off = this_int_off;
3792 }
3793
3794 int subword_off = st_off - this_int_off;
3795 int_map |= right_n_bits(st_size) << subword_off;
3796 if ((int_map & FULL_MAP) == FULL_MAP) {
3797 return this_int_off; // we found a complete word init
3798 }
3799
3800 // Did this store hit or cross the word boundary?
3801 intptr_t next_int_off = align_size_down(st_off + st_size, BytesPerInt);
3802 if (next_int_off == this_int_off + BytesPerInt) {
3803 // We passed the current int, without fully initializing it.
3804 int_map_off = next_int_off;
3805 int_map >>= BytesPerInt;
3806 } else if (next_int_off > this_int_off + BytesPerInt) {
3807 // We passed the current and next int.
3808 return this_int_off + BytesPerInt;
3809 }
3810 }
3811
3812 return -1;
3813 }
3814
3815
3816 // Called when the associated AllocateNode is expanded into CFG.
3817 // At this point, we may perform additional optimizations.
3818 // Linearize the stores by ascending offset, to make memory
3819 // activity as coherent as possible.
3820 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
3821 intptr_t header_size,
3822 Node* size_in_bytes,
3823 PhaseGVN* phase) {
3824 assert(!is_complete(), "not already complete");
3825 assert(stores_are_sane(phase), "");
3826 assert(allocation() != NULL, "must be present");
3827
3828 remove_extra_zeroes();
3829
3830 if (ReduceFieldZeroing || ReduceBulkZeroing)
3831 // reduce instruction count for common initialization patterns
3832 coalesce_subword_stores(header_size, size_in_bytes, phase);
3833
3834 Node* zmem = zero_memory(); // initially zero memory state
3835 Node* inits = zmem; // accumulating a linearized chain of inits
3836 #ifdef ASSERT
3837 intptr_t first_offset = allocation()->minimum_header_size();
3838 intptr_t last_init_off = first_offset; // previous init offset
3839 intptr_t last_init_end = first_offset; // previous init offset+size
3840 intptr_t last_tile_end = first_offset; // previous tile offset+size
3841 #endif
3842 intptr_t zeroes_done = header_size;
3843
3844 bool do_zeroing = true; // we might give up if inits are very sparse
3845 int big_init_gaps = 0; // how many large gaps have we seen?
3846
3847 if (UseTLAB && ZeroTLAB) do_zeroing = false;
3848 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
3849
3850 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3851 Node* st = in(i);
3852 intptr_t st_off = get_store_offset(st, phase);
3853 if (st_off < 0)
3854 break; // unknown junk in the inits
3855 if (st->in(MemNode::Memory) != zmem)
3856 break; // complicated store chains somehow in list
3857
3858 int st_size = st->as_Store()->memory_size();
3859 intptr_t next_init_off = st_off + st_size;
3860
3861 if (do_zeroing && zeroes_done < next_init_off) {
3862 // See if this store needs a zero before it or under it.
3863 intptr_t zeroes_needed = st_off;
3864
3865 if (st_size < BytesPerInt) {
3866 // Look for subword stores which only partially initialize words.
3867 // If we find some, we must lay down some word-level zeroes first,
3868 // underneath the subword stores.
3869 //
3870 // Examples:
3871 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
3872 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
3873 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
3874 //
3875 // Note: coalesce_subword_stores may have already done this,
3876 // if it was prompted by constant non-zero subword initializers.
3877 // But this case can still arise with non-constant stores.
3878
3879 intptr_t next_full_store = find_next_fullword_store(i, phase);
3880
3881 // In the examples above:
3882 // in(i) p q r s x y z
3883 // st_off 12 13 14 15 12 13 14
3884 // st_size 1 1 1 1 1 1 1
3885 // next_full_s. 12 16 16 16 16 16 16
3886 // z's_done 12 16 16 16 12 16 12
3887 // z's_needed 12 16 16 16 16 16 16
3888 // zsize 0 0 0 0 4 0 4
3889 if (next_full_store < 0) {
3890 // Conservative tack: Zero to end of current word.
3891 zeroes_needed = align_size_up(zeroes_needed, BytesPerInt);
3892 } else {
3893 // Zero to beginning of next fully initialized word.
3894 // Or, don't zero at all, if we are already in that word.
3895 assert(next_full_store >= zeroes_needed, "must go forward");
3896 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
3897 zeroes_needed = next_full_store;
3898 }
3899 }
3900
3901 if (zeroes_needed > zeroes_done) {
3902 intptr_t zsize = zeroes_needed - zeroes_done;
3903 // Do some incremental zeroing on rawmem, in parallel with inits.
3904 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3905 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3906 zeroes_done, zeroes_needed,
3907 phase);
3908 zeroes_done = zeroes_needed;
3909 if (zsize > InitArrayShortSize && ++big_init_gaps > 2)
3910 do_zeroing = false; // leave the hole, next time
3911 }
3912 }
3913
3914 // Collect the store and move on:
3915 st->set_req(MemNode::Memory, inits);
3916 inits = st; // put it on the linearized chain
3917 set_req(i, zmem); // unhook from previous position
3918
3919 if (zeroes_done == st_off)
3920 zeroes_done = next_init_off;
3921
3922 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
3923
3924 #ifdef ASSERT
3925 // Various order invariants. Weaker than stores_are_sane because
3926 // a large constant tile can be filled in by smaller non-constant stores.
3927 assert(st_off >= last_init_off, "inits do not reverse");
3928 last_init_off = st_off;
3929 const Type* val = NULL;
3930 if (st_size >= BytesPerInt &&
3931 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
3932 (int)val->basic_type() < (int)T_OBJECT) {
3933 assert(st_off >= last_tile_end, "tiles do not overlap");
3934 assert(st_off >= last_init_end, "tiles do not overwrite inits");
3935 last_tile_end = MAX2(last_tile_end, next_init_off);
3936 } else {
3937 intptr_t st_tile_end = align_size_up(next_init_off, BytesPerLong);
3938 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
3939 assert(st_off >= last_init_end, "inits do not overlap");
3940 last_init_end = next_init_off; // it's a non-tile
3941 }
3942 #endif //ASSERT
3943 }
3944
3945 remove_extra_zeroes(); // clear out all the zmems left over
3946 add_req(inits);
3947
3948 if (!(UseTLAB && ZeroTLAB)) {
3949 // If anything remains to be zeroed, zero it all now.
3950 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3951 // if it is the last unused 4 bytes of an instance, forget about it
3952 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
3953 if (zeroes_done + BytesPerLong >= size_limit) {
3954 assert(allocation() != NULL, "");
3955 if (allocation()->Opcode() == Op_Allocate) {
3956 Node* klass_node = allocation()->in(AllocateNode::KlassNode);
3957 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass();
3958 if (zeroes_done == k->layout_helper())
3959 zeroes_done = size_limit;
3960 }
3961 }
3962 if (zeroes_done < size_limit) {
3963 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3964 zeroes_done, size_in_bytes, phase);
3965 }
3966 }
3967
3968 set_complete(phase);
3969 return rawmem;
3970 }
3971
3972
3973 #ifdef ASSERT
3974 bool InitializeNode::stores_are_sane(PhaseTransform* phase) {
3975 if (is_complete())
3976 return true; // stores could be anything at this point
3977 assert(allocation() != NULL, "must be present");
3978 intptr_t last_off = allocation()->minimum_header_size();
3979 for (uint i = InitializeNode::RawStores; i < req(); i++) {
3980 Node* st = in(i);
3981 intptr_t st_off = get_store_offset(st, phase);
3982 if (st_off < 0) continue; // ignore dead garbage
3983 if (last_off > st_off) {
3984 tty->print_cr("*** bad store offset at %d: " INTX_FORMAT " > " INTX_FORMAT, i, last_off, st_off);
3985 this->dump(2);
3986 assert(false, "ascending store offsets");
3987 return false;
3988 }
3989 last_off = st_off + st->as_Store()->memory_size();
3990 }
3991 return true;
3992 }
3993 #endif //ASSERT
3994
3995
3996
3997
3998 //============================MergeMemNode=====================================
3999 //
4000 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
4001 // contributing store or call operations. Each contributor provides the memory
4002 // state for a particular "alias type" (see Compile::alias_type). For example,
4003 // if a MergeMem has an input X for alias category #6, then any memory reference
4004 // to alias category #6 may use X as its memory state input, as an exact equivalent
4005 // to using the MergeMem as a whole.
4006 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
4007 //
4008 // (Here, the <N> notation gives the index of the relevant adr_type.)
4009 //
4010 // In one special case (and more cases in the future), alias categories overlap.
4011 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
4012 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
4013 // it is exactly equivalent to that state W:
4014 // MergeMem(<Bot>: W) <==> W
4015 //
4016 // Usually, the merge has more than one input. In that case, where inputs
4017 // overlap (i.e., one is Bot), the narrower alias type determines the memory
4018 // state for that type, and the wider alias type (Bot) fills in everywhere else:
4019 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
4020 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
4021 //
4022 // A merge can take a "wide" memory state as one of its narrow inputs.
4023 // This simply means that the merge observes out only the relevant parts of
4024 // the wide input. That is, wide memory states arriving at narrow merge inputs
4025 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
4026 //
4027 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
4028 // and that memory slices "leak through":
4029 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
4030 //
4031 // But, in such a cascade, repeated memory slices can "block the leak":
4032 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
4033 //
4034 // In the last example, Y is not part of the combined memory state of the
4035 // outermost MergeMem. The system must, of course, prevent unschedulable
4036 // memory states from arising, so you can be sure that the state Y is somehow
4037 // a precursor to state Y'.
4038 //
4039 //
4040 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
4041 // of each MergeMemNode array are exactly the numerical alias indexes, including
4042 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
4043 // Compile::alias_type (and kin) produce and manage these indexes.
4044 //
4045 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
4046 // (Note that this provides quick access to the top node inside MergeMem methods,
4047 // without the need to reach out via TLS to Compile::current.)
4048 //
4049 // As a consequence of what was just described, a MergeMem that represents a full
4050 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
4051 // containing all alias categories.
4052 //
4053 // MergeMem nodes never (?) have control inputs, so in(0) is NULL.
4054 //
4055 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
4056 // a memory state for the alias type <N>, or else the top node, meaning that
4057 // there is no particular input for that alias type. Note that the length of
4058 // a MergeMem is variable, and may be extended at any time to accommodate new
4059 // memory states at larger alias indexes. When merges grow, they are of course
4060 // filled with "top" in the unused in() positions.
4061 //
4062 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
4063 // (Top was chosen because it works smoothly with passes like GCM.)
4064 //
4065 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
4066 // the type of random VM bits like TLS references.) Since it is always the
4067 // first non-Bot memory slice, some low-level loops use it to initialize an
4068 // index variable: for (i = AliasIdxRaw; i < req(); i++).
4069 //
4070 //
4071 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
4072 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
4073 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
4074 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
4075 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
4076 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
4077 //
4078 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
4079 // really that different from the other memory inputs. An abbreviation called
4080 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
4081 //
4082 //
4083 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
4084 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
4085 // that "emerges though" the base memory will be marked as excluding the alias types
4086 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
4087 //
4088 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
4089 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
4090 //
4091 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
4092 // (It is currently unimplemented.) As you can see, the resulting merge is
4093 // actually a disjoint union of memory states, rather than an overlay.
4094 //
4095
4096 //------------------------------MergeMemNode-----------------------------------
4097 Node* MergeMemNode::make_empty_memory() {
4098 Node* empty_memory = (Node*) Compile::current()->top();
4099 assert(empty_memory->is_top(), "correct sentinel identity");
4100 return empty_memory;
4101 }
4102
4103 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
4104 init_class_id(Class_MergeMem);
4105 // all inputs are nullified in Node::Node(int)
4106 // set_input(0, NULL); // no control input
4107
4108 // Initialize the edges uniformly to top, for starters.
4109 Node* empty_mem = make_empty_memory();
4110 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
4111 init_req(i,empty_mem);
4112 }
4113 assert(empty_memory() == empty_mem, "");
4114
4115 if( new_base != NULL && new_base->is_MergeMem() ) {
4116 MergeMemNode* mdef = new_base->as_MergeMem();
4117 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
4118 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
4119 mms.set_memory(mms.memory2());
4120 }
4121 assert(base_memory() == mdef->base_memory(), "");
4122 } else {
4123 set_base_memory(new_base);
4124 }
4125 }
4126
4127 // Make a new, untransformed MergeMem with the same base as 'mem'.
4128 // If mem is itself a MergeMem, populate the result with the same edges.
4129 MergeMemNode* MergeMemNode::make(Node* mem) {
4130 return new MergeMemNode(mem);
4131 }
4132
4133 //------------------------------cmp--------------------------------------------
4134 uint MergeMemNode::hash() const { return NO_HASH; }
4135 uint MergeMemNode::cmp( const Node &n ) const {
4136 return (&n == this); // Always fail except on self
4137 }
4138
4139 //------------------------------Identity---------------------------------------
4140 Node* MergeMemNode::Identity(PhaseGVN* phase) {
4141 // Identity if this merge point does not record any interesting memory
4142 // disambiguations.
4143 Node* base_mem = base_memory();
4144 Node* empty_mem = empty_memory();
4145 if (base_mem != empty_mem) { // Memory path is not dead?
4146 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4147 Node* mem = in(i);
4148 if (mem != empty_mem && mem != base_mem) {
4149 return this; // Many memory splits; no change
4150 }
4151 }
4152 }
4153 return base_mem; // No memory splits; ID on the one true input
4154 }
4155
4156 //------------------------------Ideal------------------------------------------
4157 // This method is invoked recursively on chains of MergeMem nodes
4158 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4159 // Remove chain'd MergeMems
4160 //
4161 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
4162 // relative to the "in(Bot)". Since we are patching both at the same time,
4163 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
4164 // but rewrite each "in(i)" relative to the new "in(Bot)".
4165 Node *progress = NULL;
4166
4167
4168 Node* old_base = base_memory();
4169 Node* empty_mem = empty_memory();
4170 if (old_base == empty_mem)
4171 return NULL; // Dead memory path.
4172
4173 MergeMemNode* old_mbase;
4174 if (old_base != NULL && old_base->is_MergeMem())
4175 old_mbase = old_base->as_MergeMem();
4176 else
4177 old_mbase = NULL;
4178 Node* new_base = old_base;
4179
4180 // simplify stacked MergeMems in base memory
4181 if (old_mbase) new_base = old_mbase->base_memory();
4182
4183 // the base memory might contribute new slices beyond my req()
4184 if (old_mbase) grow_to_match(old_mbase);
4185
4186 // Look carefully at the base node if it is a phi.
4187 PhiNode* phi_base;
4188 if (new_base != NULL && new_base->is_Phi())
4189 phi_base = new_base->as_Phi();
4190 else
4191 phi_base = NULL;
4192
4193 Node* phi_reg = NULL;
4194 uint phi_len = (uint)-1;
4195 if (phi_base != NULL && !phi_base->is_copy()) {
4196 // do not examine phi if degraded to a copy
4197 phi_reg = phi_base->region();
4198 phi_len = phi_base->req();
4199 // see if the phi is unfinished
4200 for (uint i = 1; i < phi_len; i++) {
4201 if (phi_base->in(i) == NULL) {
4202 // incomplete phi; do not look at it yet!
4203 phi_reg = NULL;
4204 phi_len = (uint)-1;
4205 break;
4206 }
4207 }
4208 }
4209
4210 // Note: We do not call verify_sparse on entry, because inputs
4211 // can normalize to the base_memory via subsume_node or similar
4212 // mechanisms. This method repairs that damage.
4213
4214 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
4215
4216 // Look at each slice.
4217 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4218 Node* old_in = in(i);
4219 // calculate the old memory value
4220 Node* old_mem = old_in;
4221 if (old_mem == empty_mem) old_mem = old_base;
4222 assert(old_mem == memory_at(i), "");
4223
4224 // maybe update (reslice) the old memory value
4225
4226 // simplify stacked MergeMems
4227 Node* new_mem = old_mem;
4228 MergeMemNode* old_mmem;
4229 if (old_mem != NULL && old_mem->is_MergeMem())
4230 old_mmem = old_mem->as_MergeMem();
4231 else
4232 old_mmem = NULL;
4233 if (old_mmem == this) {
4234 // This can happen if loops break up and safepoints disappear.
4235 // A merge of BotPtr (default) with a RawPtr memory derived from a
4236 // safepoint can be rewritten to a merge of the same BotPtr with
4237 // the BotPtr phi coming into the loop. If that phi disappears
4238 // also, we can end up with a self-loop of the mergemem.
4239 // In general, if loops degenerate and memory effects disappear,
4240 // a mergemem can be left looking at itself. This simply means
4241 // that the mergemem's default should be used, since there is
4242 // no longer any apparent effect on this slice.
4243 // Note: If a memory slice is a MergeMem cycle, it is unreachable
4244 // from start. Update the input to TOP.
4245 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
4246 }
4247 else if (old_mmem != NULL) {
4248 new_mem = old_mmem->memory_at(i);
4249 }
4250 // else preceding memory was not a MergeMem
4251
4252 // replace equivalent phis (unfortunately, they do not GVN together)
4253 if (new_mem != NULL && new_mem != new_base &&
4254 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) {
4255 if (new_mem->is_Phi()) {
4256 PhiNode* phi_mem = new_mem->as_Phi();
4257 for (uint i = 1; i < phi_len; i++) {
4258 if (phi_base->in(i) != phi_mem->in(i)) {
4259 phi_mem = NULL;
4260 break;
4261 }
4262 }
4263 if (phi_mem != NULL) {
4264 // equivalent phi nodes; revert to the def
4265 new_mem = new_base;
4266 }
4267 }
4268 }
4269
4270 // maybe store down a new value
4271 Node* new_in = new_mem;
4272 if (new_in == new_base) new_in = empty_mem;
4273
4274 if (new_in != old_in) {
4275 // Warning: Do not combine this "if" with the previous "if"
4276 // A memory slice might have be be rewritten even if it is semantically
4277 // unchanged, if the base_memory value has changed.
4278 set_req(i, new_in);
4279 progress = this; // Report progress
4280 }
4281 }
4282
4283 if (new_base != old_base) {
4284 set_req(Compile::AliasIdxBot, new_base);
4285 // Don't use set_base_memory(new_base), because we need to update du.
4286 assert(base_memory() == new_base, "");
4287 progress = this;
4288 }
4289
4290 if( base_memory() == this ) {
4291 // a self cycle indicates this memory path is dead
4292 set_req(Compile::AliasIdxBot, empty_mem);
4293 }
4294
4295 // Resolve external cycles by calling Ideal on a MergeMem base_memory
4296 // Recursion must occur after the self cycle check above
4297 if( base_memory()->is_MergeMem() ) {
4298 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
4299 Node *m = phase->transform(new_mbase); // Rollup any cycles
4300 if( m != NULL && (m->is_top() ||
4301 m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem) ) {
4302 // propagate rollup of dead cycle to self
4303 set_req(Compile::AliasIdxBot, empty_mem);
4304 }
4305 }
4306
4307 if( base_memory() == empty_mem ) {
4308 progress = this;
4309 // Cut inputs during Parse phase only.
4310 // During Optimize phase a dead MergeMem node will be subsumed by Top.
4311 if( !can_reshape ) {
4312 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4313 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
4314 }
4315 }
4316 }
4317
4318 if( !progress && base_memory()->is_Phi() && can_reshape ) {
4319 // Check if PhiNode::Ideal's "Split phis through memory merges"
4320 // transform should be attempted. Look for this->phi->this cycle.
4321 uint merge_width = req();
4322 if (merge_width > Compile::AliasIdxRaw) {
4323 PhiNode* phi = base_memory()->as_Phi();
4324 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
4325 if (phi->in(i) == this) {
4326 phase->is_IterGVN()->_worklist.push(phi);
4327 break;
4328 }
4329 }
4330 }
4331 }
4332
4333 assert(progress || verify_sparse(), "please, no dups of base");
4334 return progress;
4335 }
4336
4337 //-------------------------set_base_memory-------------------------------------
4338 void MergeMemNode::set_base_memory(Node *new_base) {
4339 Node* empty_mem = empty_memory();
4340 set_req(Compile::AliasIdxBot, new_base);
4341 assert(memory_at(req()) == new_base, "must set default memory");
4342 // Clear out other occurrences of new_base:
4343 if (new_base != empty_mem) {
4344 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4345 if (in(i) == new_base) set_req(i, empty_mem);
4346 }
4347 }
4348 }
4349
4350 //------------------------------out_RegMask------------------------------------
4351 const RegMask &MergeMemNode::out_RegMask() const {
4352 return RegMask::Empty;
4353 }
4354
4355 //------------------------------dump_spec--------------------------------------
4356 #ifndef PRODUCT
4357 void MergeMemNode::dump_spec(outputStream *st) const {
4358 st->print(" {");
4359 Node* base_mem = base_memory();
4360 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
4361 Node* mem = (in(i) != NULL) ? memory_at(i) : base_mem;
4362 if (mem == base_mem) { st->print(" -"); continue; }
4363 st->print( " N%d:", mem->_idx );
4364 Compile::current()->get_adr_type(i)->dump_on(st);
4365 }
4366 st->print(" }");
4367 }
4368 #endif // !PRODUCT
4369
4370
4371 #ifdef ASSERT
4372 static bool might_be_same(Node* a, Node* b) {
4373 if (a == b) return true;
4374 if (!(a->is_Phi() || b->is_Phi())) return false;
4375 // phis shift around during optimization
4376 return true; // pretty stupid...
4377 }
4378
4379 // verify a narrow slice (either incoming or outgoing)
4380 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
4381 if (!VerifyAliases) return; // don't bother to verify unless requested
4382 if (is_error_reported()) return; // muzzle asserts when debugging an error
4383 if (Node::in_dump()) return; // muzzle asserts when printing
4384 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
4385 assert(n != NULL, "");
4386 // Elide intervening MergeMem's
4387 while (n->is_MergeMem()) {
4388 n = n->as_MergeMem()->memory_at(alias_idx);
4389 }
4390 Compile* C = Compile::current();
4391 const TypePtr* n_adr_type = n->adr_type();
4392 if (n == m->empty_memory()) {
4393 // Implicit copy of base_memory()
4394 } else if (n_adr_type != TypePtr::BOTTOM) {
4395 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type");
4396 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
4397 } else {
4398 // A few places like make_runtime_call "know" that VM calls are narrow,
4399 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
4400 bool expected_wide_mem = false;
4401 if (n == m->base_memory()) {
4402 expected_wide_mem = true;
4403 } else if (alias_idx == Compile::AliasIdxRaw ||
4404 n == m->memory_at(Compile::AliasIdxRaw)) {
4405 expected_wide_mem = true;
4406 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
4407 // memory can "leak through" calls on channels that
4408 // are write-once. Allow this also.
4409 expected_wide_mem = true;
4410 }
4411 assert(expected_wide_mem, "expected narrow slice replacement");
4412 }
4413 }
4414 #else // !ASSERT
4415 #define verify_memory_slice(m,i,n) (void)(0) // PRODUCT version is no-op
4416 #endif
4417
4418
4419 //-----------------------------memory_at---------------------------------------
4420 Node* MergeMemNode::memory_at(uint alias_idx) const {
4421 assert(alias_idx >= Compile::AliasIdxRaw ||
4422 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0,
4423 "must avoid base_memory and AliasIdxTop");
4424
4425 // Otherwise, it is a narrow slice.
4426 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
4427 Compile *C = Compile::current();
4428 if (is_empty_memory(n)) {
4429 // the array is sparse; empty slots are the "top" node
4430 n = base_memory();
4431 assert(Node::in_dump()
4432 || n == NULL || n->bottom_type() == Type::TOP
4433 || n->adr_type() == NULL // address is TOP
4434 || n->adr_type() == TypePtr::BOTTOM
4435 || n->adr_type() == TypeRawPtr::BOTTOM
4436 || Compile::current()->AliasLevel() == 0,
4437 "must be a wide memory");
4438 // AliasLevel == 0 if we are organizing the memory states manually.
4439 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
4440 } else {
4441 // make sure the stored slice is sane
4442 #ifdef ASSERT
4443 if (is_error_reported() || Node::in_dump()) {
4444 } else if (might_be_same(n, base_memory())) {
4445 // Give it a pass: It is a mostly harmless repetition of the base.
4446 // This can arise normally from node subsumption during optimization.
4447 } else {
4448 verify_memory_slice(this, alias_idx, n);
4449 }
4450 #endif
4451 }
4452 return n;
4453 }
4454
4455 //---------------------------set_memory_at-------------------------------------
4456 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
4457 verify_memory_slice(this, alias_idx, n);
4458 Node* empty_mem = empty_memory();
4459 if (n == base_memory()) n = empty_mem; // collapse default
4460 uint need_req = alias_idx+1;
4461 if (req() < need_req) {
4462 if (n == empty_mem) return; // already the default, so do not grow me
4463 // grow the sparse array
4464 do {
4465 add_req(empty_mem);
4466 } while (req() < need_req);
4467 }
4468 set_req( alias_idx, n );
4469 }
4470
4471
4472
4473 //--------------------------iteration_setup------------------------------------
4474 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
4475 if (other != NULL) {
4476 grow_to_match(other);
4477 // invariant: the finite support of mm2 is within mm->req()
4478 #ifdef ASSERT
4479 for (uint i = req(); i < other->req(); i++) {
4480 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
4481 }
4482 #endif
4483 }
4484 // Replace spurious copies of base_memory by top.
4485 Node* base_mem = base_memory();
4486 if (base_mem != NULL && !base_mem->is_top()) {
4487 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
4488 if (in(i) == base_mem)
4489 set_req(i, empty_memory());
4490 }
4491 }
4492 }
4493
4494 //---------------------------grow_to_match-------------------------------------
4495 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
4496 Node* empty_mem = empty_memory();
4497 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
4498 // look for the finite support of the other memory
4499 for (uint i = other->req(); --i >= req(); ) {
4500 if (other->in(i) != empty_mem) {
4501 uint new_len = i+1;
4502 while (req() < new_len) add_req(empty_mem);
4503 break;
4504 }
4505 }
4506 }
4507
4508 //---------------------------verify_sparse-------------------------------------
4509 #ifndef PRODUCT
4510 bool MergeMemNode::verify_sparse() const {
4511 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
4512 Node* base_mem = base_memory();
4513 // The following can happen in degenerate cases, since empty==top.
4514 if (is_empty_memory(base_mem)) return true;
4515 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4516 assert(in(i) != NULL, "sane slice");
4517 if (in(i) == base_mem) return false; // should have been the sentinel value!
4518 }
4519 return true;
4520 }
4521
4522 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
4523 Node* n;
4524 n = mm->in(idx);
4525 if (mem == n) return true; // might be empty_memory()
4526 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
4527 if (mem == n) return true;
4528 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) {
4529 if (mem == n) return true;
4530 if (n == NULL) break;
4531 }
4532 return false;
4533 }
4534 #endif // !PRODUCT