1 /*
2 * Copyright (c) 1997, 2018, 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 "gc/shared/barrierSet.hpp"
29 #include "gc/shared/c2/barrierSetC2.hpp"
30 #include "memory/allocation.inline.hpp"
31 #include "memory/resourceArea.hpp"
32 #include "oops/objArrayKlass.hpp"
33 #include "opto/addnode.hpp"
34 #include "opto/arraycopynode.hpp"
35 #include "opto/cfgnode.hpp"
36 #include "opto/compile.hpp"
37 #include "opto/connode.hpp"
38 #include "opto/convertnode.hpp"
39 #include "opto/loopnode.hpp"
40 #include "opto/machnode.hpp"
41 #include "opto/matcher.hpp"
42 #include "opto/memnode.hpp"
43 #include "opto/mulnode.hpp"
44 #include "opto/narrowptrnode.hpp"
45 #include "opto/phaseX.hpp"
46 #include "opto/regmask.hpp"
47 #include "utilities/align.hpp"
48 #include "utilities/copy.hpp"
49 #include "utilities/macros.hpp"
50 #include "utilities/vmError.hpp"
51 #if INCLUDE_ZGC
52 #include "gc/z/c2/zBarrierSetC2.hpp"
53 #endif
54
55 // Portions of code courtesy of Clifford Click
56
57 // Optimization - Graph Style
58
59 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st);
60
61 //=============================================================================
62 uint MemNode::size_of() const { return sizeof(*this); }
63
64 const TypePtr *MemNode::adr_type() const {
65 Node* adr = in(Address);
66 if (adr == NULL) return NULL; // node is dead
67 const TypePtr* cross_check = NULL;
68 DEBUG_ONLY(cross_check = _adr_type);
69 return calculate_adr_type(adr->bottom_type(), cross_check);
70 }
71
72 bool MemNode::check_if_adr_maybe_raw(Node* adr) {
73 if (adr != NULL) {
74 if (adr->bottom_type()->base() == Type::RawPtr || adr->bottom_type()->base() == Type::AnyPtr) {
75 return true;
76 }
77 }
78 return false;
79 }
80
81 #ifndef PRODUCT
82 void MemNode::dump_spec(outputStream *st) const {
83 if (in(Address) == NULL) return; // node is dead
84 #ifndef ASSERT
85 // fake the missing field
86 const TypePtr* _adr_type = NULL;
87 if (in(Address) != NULL)
88 _adr_type = in(Address)->bottom_type()->isa_ptr();
89 #endif
90 dump_adr_type(this, _adr_type, st);
91
92 Compile* C = Compile::current();
93 if (C->alias_type(_adr_type)->is_volatile()) {
94 st->print(" Volatile!");
95 }
96 if (_unaligned_access) {
97 st->print(" unaligned");
98 }
99 if (_mismatched_access) {
100 st->print(" mismatched");
101 }
102 }
103
104 void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) {
105 st->print(" @");
106 if (adr_type == NULL) {
107 st->print("NULL");
108 } else {
109 adr_type->dump_on(st);
110 Compile* C = Compile::current();
111 Compile::AliasType* atp = NULL;
112 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type);
113 if (atp == NULL)
114 st->print(", idx=?\?;");
115 else if (atp->index() == Compile::AliasIdxBot)
116 st->print(", idx=Bot;");
117 else if (atp->index() == Compile::AliasIdxTop)
118 st->print(", idx=Top;");
119 else if (atp->index() == Compile::AliasIdxRaw)
120 st->print(", idx=Raw;");
121 else {
122 ciField* field = atp->field();
123 if (field) {
124 st->print(", name=");
125 field->print_name_on(st);
126 }
127 st->print(", idx=%d;", atp->index());
128 }
129 }
130 }
131
132 extern void print_alias_types();
133
134 #endif
135
136 Node *MemNode::optimize_simple_memory_chain(Node *mchain, const TypeOopPtr *t_oop, Node *load, PhaseGVN *phase) {
137 assert((t_oop != NULL), "sanity");
138 bool is_instance = t_oop->is_known_instance_field();
139 bool is_boxed_value_load = t_oop->is_ptr_to_boxed_value() &&
140 (load != NULL) && load->is_Load() &&
141 (phase->is_IterGVN() != NULL);
142 if (!(is_instance || is_boxed_value_load))
143 return mchain; // don't try to optimize non-instance types
144 uint instance_id = t_oop->instance_id();
145 Node *start_mem = phase->C->start()->proj_out_or_null(TypeFunc::Memory);
146 Node *prev = NULL;
147 Node *result = mchain;
148 while (prev != result) {
149 prev = result;
150 if (result == start_mem)
151 break; // hit one of our sentinels
152 // skip over a call which does not affect this memory slice
153 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {
154 Node *proj_in = result->in(0);
155 if (proj_in->is_Allocate() && proj_in->_idx == instance_id) {
156 break; // hit one of our sentinels
157 } else if (proj_in->is_Call()) {
158 // ArrayCopyNodes processed here as well
159 CallNode *call = proj_in->as_Call();
160 if (!call->may_modify(t_oop, phase)) { // returns false for instances
161 result = call->in(TypeFunc::Memory);
162 }
163 } else if (proj_in->is_Initialize()) {
164 AllocateNode* alloc = proj_in->as_Initialize()->allocation();
165 // Stop if this is the initialization for the object instance which
166 // contains this memory slice, otherwise skip over it.
167 if ((alloc == NULL) || (alloc->_idx == instance_id)) {
168 break;
169 }
170 if (is_instance) {
171 result = proj_in->in(TypeFunc::Memory);
172 } else if (is_boxed_value_load) {
173 Node* klass = alloc->in(AllocateNode::KlassNode);
174 const TypeKlassPtr* tklass = phase->type(klass)->is_klassptr();
175 if (tklass->klass_is_exact() && !tklass->klass()->equals(t_oop->klass())) {
176 result = proj_in->in(TypeFunc::Memory); // not related allocation
177 }
178 }
179 } else if (proj_in->is_MemBar()) {
180 ArrayCopyNode* ac = NULL;
181 if (ArrayCopyNode::may_modify(t_oop, proj_in->as_MemBar(), phase, ac)) {
182 break;
183 }
184 result = proj_in->in(TypeFunc::Memory);
185 } else {
186 assert(false, "unexpected projection");
187 }
188 } else if (result->is_ClearArray()) {
189 if (!is_instance || !ClearArrayNode::step_through(&result, instance_id, phase)) {
190 // Can not bypass initialization of the instance
191 // we are looking for.
192 break;
193 }
194 // Otherwise skip it (the call updated 'result' value).
195 } else if (result->is_MergeMem()) {
196 result = step_through_mergemem(phase, result->as_MergeMem(), t_oop, NULL, tty);
197 }
198 }
199 return result;
200 }
201
202 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, Node *load, PhaseGVN *phase) {
203 const TypeOopPtr* t_oop = t_adr->isa_oopptr();
204 if (t_oop == NULL)
205 return mchain; // don't try to optimize non-oop types
206 Node* result = optimize_simple_memory_chain(mchain, t_oop, load, phase);
207 bool is_instance = t_oop->is_known_instance_field();
208 PhaseIterGVN *igvn = phase->is_IterGVN();
209 if (is_instance && igvn != NULL && result->is_Phi()) {
210 PhiNode *mphi = result->as_Phi();
211 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
212 const TypePtr *t = mphi->adr_type();
213 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
214 (t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
215 t->is_oopptr()->cast_to_exactness(true)
216 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
217 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop)) {
218 // clone the Phi with our address type
219 result = mphi->split_out_instance(t_adr, igvn);
220 } else {
221 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain");
222 }
223 }
224 return result;
225 }
226
227 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) {
228 uint alias_idx = phase->C->get_alias_index(tp);
229 Node *mem = mmem;
230 #ifdef ASSERT
231 {
232 // Check that current type is consistent with the alias index used during graph construction
233 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
234 bool consistent = adr_check == NULL || adr_check->empty() ||
235 phase->C->must_alias(adr_check, alias_idx );
236 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
237 if( !consistent && adr_check != NULL && !adr_check->empty() &&
238 tp->isa_aryptr() && tp->offset() == Type::OffsetBot &&
239 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot &&
240 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() ||
241 adr_check->offset() == oopDesc::klass_offset_in_bytes() ||
242 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) {
243 // don't assert if it is dead code.
244 consistent = true;
245 }
246 if( !consistent ) {
247 st->print("alias_idx==%d, adr_check==", alias_idx);
248 if( adr_check == NULL ) {
249 st->print("NULL");
250 } else {
251 adr_check->dump();
252 }
253 st->cr();
254 print_alias_types();
255 assert(consistent, "adr_check must match alias idx");
256 }
257 }
258 #endif
259 // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally
260 // means an array I have not precisely typed yet. Do not do any
261 // alias stuff with it any time soon.
262 const TypeOopPtr *toop = tp->isa_oopptr();
263 if( tp->base() != Type::AnyPtr &&
264 !(toop &&
265 toop->klass() != NULL &&
266 toop->klass()->is_java_lang_Object() &&
267 toop->offset() == Type::OffsetBot) ) {
268 // compress paths and change unreachable cycles to TOP
269 // If not, we can update the input infinitely along a MergeMem cycle
270 // Equivalent code in PhiNode::Ideal
271 Node* m = phase->transform(mmem);
272 // If transformed to a MergeMem, get the desired slice
273 // Otherwise the returned node represents memory for every slice
274 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
275 // Update input if it is progress over what we have now
276 }
277 return mem;
278 }
279
280 //--------------------------Ideal_common---------------------------------------
281 // Look for degenerate control and memory inputs. Bypass MergeMem inputs.
282 // Unhook non-raw memories from complete (macro-expanded) initializations.
283 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
284 // If our control input is a dead region, kill all below the region
285 Node *ctl = in(MemNode::Control);
286 if (ctl && remove_dead_region(phase, can_reshape))
287 return this;
288 ctl = in(MemNode::Control);
289 // Don't bother trying to transform a dead node
290 if (ctl && ctl->is_top()) return NodeSentinel;
291
292 PhaseIterGVN *igvn = phase->is_IterGVN();
293 // Wait if control on the worklist.
294 if (ctl && can_reshape && igvn != NULL) {
295 Node* bol = NULL;
296 Node* cmp = NULL;
297 if (ctl->in(0)->is_If()) {
298 assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity");
299 bol = ctl->in(0)->in(1);
300 if (bol->is_Bool())
301 cmp = ctl->in(0)->in(1)->in(1);
302 }
303 if (igvn->_worklist.member(ctl) ||
304 (bol != NULL && igvn->_worklist.member(bol)) ||
305 (cmp != NULL && igvn->_worklist.member(cmp)) ) {
306 // This control path may be dead.
307 // Delay this memory node transformation until the control is processed.
308 phase->is_IterGVN()->_worklist.push(this);
309 return NodeSentinel; // caller will return NULL
310 }
311 }
312 // Ignore if memory is dead, or self-loop
313 Node *mem = in(MemNode::Memory);
314 if (phase->type( mem ) == Type::TOP) return NodeSentinel; // caller will return NULL
315 assert(mem != this, "dead loop in MemNode::Ideal");
316
317 if (can_reshape && igvn != NULL && igvn->_worklist.member(mem)) {
318 // This memory slice may be dead.
319 // Delay this mem node transformation until the memory is processed.
320 phase->is_IterGVN()->_worklist.push(this);
321 return NodeSentinel; // caller will return NULL
322 }
323
324 Node *address = in(MemNode::Address);
325 const Type *t_adr = phase->type(address);
326 if (t_adr == Type::TOP) return NodeSentinel; // caller will return NULL
327
328 if (can_reshape && igvn != NULL &&
329 (igvn->_worklist.member(address) ||
330 (igvn->_worklist.size() > 0 && t_adr != adr_type())) ) {
331 // The address's base and type may change when the address is processed.
332 // Delay this mem node transformation until the address is processed.
333 phase->is_IterGVN()->_worklist.push(this);
334 return NodeSentinel; // caller will return NULL
335 }
336
337 // Do NOT remove or optimize the next lines: ensure a new alias index
338 // is allocated for an oop pointer type before Escape Analysis.
339 // Note: C++ will not remove it since the call has side effect.
340 if (t_adr->isa_oopptr()) {
341 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr());
342 }
343
344 Node* base = NULL;
345 if (address->is_AddP()) {
346 base = address->in(AddPNode::Base);
347 }
348 if (base != NULL && phase->type(base)->higher_equal(TypePtr::NULL_PTR) &&
349 !t_adr->isa_rawptr()) {
350 // Note: raw address has TOP base and top->higher_equal(TypePtr::NULL_PTR) is true.
351 // Skip this node optimization if its address has TOP base.
352 return NodeSentinel; // caller will return NULL
353 }
354
355 // Avoid independent memory operations
356 Node* old_mem = mem;
357
358 // The code which unhooks non-raw memories from complete (macro-expanded)
359 // initializations was removed. After macro-expansion all stores catched
360 // by Initialize node became raw stores and there is no information
361 // which memory slices they modify. So it is unsafe to move any memory
362 // operation above these stores. Also in most cases hooked non-raw memories
363 // were already unhooked by using information from detect_ptr_independence()
364 // and find_previous_store().
365
366 if (mem->is_MergeMem()) {
367 MergeMemNode* mmem = mem->as_MergeMem();
368 const TypePtr *tp = t_adr->is_ptr();
369
370 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
371 }
372
373 if (mem != old_mem) {
374 set_req(MemNode::Memory, mem);
375 if (can_reshape && old_mem->outcnt() == 0 && igvn != NULL) {
376 igvn->_worklist.push(old_mem);
377 }
378 if (phase->type(mem) == Type::TOP) return NodeSentinel;
379 return this;
380 }
381
382 // let the subclass continue analyzing...
383 return NULL;
384 }
385
386 // Helper function for proving some simple control dominations.
387 // Attempt to prove that all control inputs of 'dom' dominate 'sub'.
388 // Already assumes that 'dom' is available at 'sub', and that 'sub'
389 // is not a constant (dominated by the method's StartNode).
390 // Used by MemNode::find_previous_store to prove that the
391 // control input of a memory operation predates (dominates)
392 // an allocation it wants to look past.
393 bool MemNode::all_controls_dominate(Node* dom, Node* sub) {
394 if (dom == NULL || dom->is_top() || sub == NULL || sub->is_top())
395 return false; // Conservative answer for dead code
396
397 // Check 'dom'. Skip Proj and CatchProj nodes.
398 dom = dom->find_exact_control(dom);
399 if (dom == NULL || dom->is_top())
400 return false; // Conservative answer for dead code
401
402 if (dom == sub) {
403 // For the case when, for example, 'sub' is Initialize and the original
404 // 'dom' is Proj node of the 'sub'.
405 return false;
406 }
407
408 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub)
409 return true;
410
411 // 'dom' dominates 'sub' if its control edge and control edges
412 // of all its inputs dominate or equal to sub's control edge.
413
414 // Currently 'sub' is either Allocate, Initialize or Start nodes.
415 // Or Region for the check in LoadNode::Ideal();
416 // 'sub' should have sub->in(0) != NULL.
417 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() ||
418 sub->is_Region() || sub->is_Call(), "expecting only these nodes");
419
420 // Get control edge of 'sub'.
421 Node* orig_sub = sub;
422 sub = sub->find_exact_control(sub->in(0));
423 if (sub == NULL || sub->is_top())
424 return false; // Conservative answer for dead code
425
426 assert(sub->is_CFG(), "expecting control");
427
428 if (sub == dom)
429 return true;
430
431 if (sub->is_Start() || sub->is_Root())
432 return false;
433
434 {
435 // Check all control edges of 'dom'.
436
437 ResourceMark rm;
438 Arena* arena = Thread::current()->resource_area();
439 Node_List nlist(arena);
440 Unique_Node_List dom_list(arena);
441
442 dom_list.push(dom);
443 bool only_dominating_controls = false;
444
445 for (uint next = 0; next < dom_list.size(); next++) {
446 Node* n = dom_list.at(next);
447 if (n == orig_sub)
448 return false; // One of dom's inputs dominated by sub.
449 if (!n->is_CFG() && n->pinned()) {
450 // Check only own control edge for pinned non-control nodes.
451 n = n->find_exact_control(n->in(0));
452 if (n == NULL || n->is_top())
453 return false; // Conservative answer for dead code
454 assert(n->is_CFG(), "expecting control");
455 dom_list.push(n);
456 } else if (n->is_Con() || n->is_Start() || n->is_Root()) {
457 only_dominating_controls = true;
458 } else if (n->is_CFG()) {
459 if (n->dominates(sub, nlist))
460 only_dominating_controls = true;
461 else
462 return false;
463 } else {
464 // First, own control edge.
465 Node* m = n->find_exact_control(n->in(0));
466 if (m != NULL) {
467 if (m->is_top())
468 return false; // Conservative answer for dead code
469 dom_list.push(m);
470 }
471 // Now, the rest of edges.
472 uint cnt = n->req();
473 for (uint i = 1; i < cnt; i++) {
474 m = n->find_exact_control(n->in(i));
475 if (m == NULL || m->is_top())
476 continue;
477 dom_list.push(m);
478 }
479 }
480 }
481 return only_dominating_controls;
482 }
483 }
484
485 //---------------------detect_ptr_independence---------------------------------
486 // Used by MemNode::find_previous_store to prove that two base
487 // pointers are never equal.
488 // The pointers are accompanied by their associated allocations,
489 // if any, which have been previously discovered by the caller.
490 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
491 Node* p2, AllocateNode* a2,
492 PhaseTransform* phase) {
493 // Attempt to prove that these two pointers cannot be aliased.
494 // They may both manifestly be allocations, and they should differ.
495 // Or, if they are not both allocations, they can be distinct constants.
496 // Otherwise, one is an allocation and the other a pre-existing value.
497 if (a1 == NULL && a2 == NULL) { // neither an allocation
498 return (p1 != p2) && p1->is_Con() && p2->is_Con();
499 } else if (a1 != NULL && a2 != NULL) { // both allocations
500 return (a1 != a2);
501 } else if (a1 != NULL) { // one allocation a1
502 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.)
503 return all_controls_dominate(p2, a1);
504 } else { //(a2 != NULL) // one allocation a2
505 return all_controls_dominate(p1, a2);
506 }
507 return false;
508 }
509
510
511 // Find an arraycopy that must have set (can_see_stored_value=true) or
512 // could have set (can_see_stored_value=false) the value for this load
513 Node* LoadNode::find_previous_arraycopy(PhaseTransform* phase, Node* ld_alloc, Node*& mem, bool can_see_stored_value) const {
514 if (mem->is_Proj() && mem->in(0) != NULL && (mem->in(0)->Opcode() == Op_MemBarStoreStore ||
515 mem->in(0)->Opcode() == Op_MemBarCPUOrder)) {
516 Node* mb = mem->in(0);
517 if (mb->in(0) != NULL && mb->in(0)->is_Proj() &&
518 mb->in(0)->in(0) != NULL && mb->in(0)->in(0)->is_ArrayCopy()) {
519 ArrayCopyNode* ac = mb->in(0)->in(0)->as_ArrayCopy();
520 if (ac->is_clonebasic()) {
521 intptr_t offset;
522 AllocateNode* alloc = AllocateNode::Ideal_allocation(ac->in(ArrayCopyNode::Dest), phase, offset);
523 if (alloc != NULL && alloc == ld_alloc) {
524 return ac;
525 }
526 }
527 }
528 } else if (mem->is_Proj() && mem->in(0) != NULL && mem->in(0)->is_ArrayCopy()) {
529 ArrayCopyNode* ac = mem->in(0)->as_ArrayCopy();
530
531 if (ac->is_arraycopy_validated() ||
532 ac->is_copyof_validated() ||
533 ac->is_copyofrange_validated()) {
534 Node* ld_addp = in(MemNode::Address);
535 if (ld_addp->is_AddP()) {
536 Node* ld_base = ld_addp->in(AddPNode::Address);
537 Node* ld_offs = ld_addp->in(AddPNode::Offset);
538
539 Node* dest = ac->in(ArrayCopyNode::Dest);
540
541 if (dest == ld_base) {
542 const TypeX *ld_offs_t = phase->type(ld_offs)->isa_intptr_t();
543 if (ac->modifies(ld_offs_t->_lo, ld_offs_t->_hi, phase, can_see_stored_value)) {
544 return ac;
545 }
546 if (!can_see_stored_value) {
547 mem = ac->in(TypeFunc::Memory);
548 }
549 }
550 }
551 }
552 }
553 return NULL;
554 }
555
556 // The logic for reordering loads and stores uses four steps:
557 // (a) Walk carefully past stores and initializations which we
558 // can prove are independent of this load.
559 // (b) Observe that the next memory state makes an exact match
560 // with self (load or store), and locate the relevant store.
561 // (c) Ensure that, if we were to wire self directly to the store,
562 // the optimizer would fold it up somehow.
563 // (d) Do the rewiring, and return, depending on some other part of
564 // the optimizer to fold up the load.
565 // This routine handles steps (a) and (b). Steps (c) and (d) are
566 // specific to loads and stores, so they are handled by the callers.
567 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.)
568 //
569 Node* MemNode::find_previous_store(PhaseTransform* phase) {
570 Node* ctrl = in(MemNode::Control);
571 Node* adr = in(MemNode::Address);
572 intptr_t offset = 0;
573 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
574 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase);
575
576 if (offset == Type::OffsetBot)
577 return NULL; // cannot unalias unless there are precise offsets
578
579 const bool adr_maybe_raw = check_if_adr_maybe_raw(adr);
580 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr();
581
582 intptr_t size_in_bytes = memory_size();
583
584 Node* mem = in(MemNode::Memory); // start searching here...
585
586 int cnt = 50; // Cycle limiter
587 for (;;) { // While we can dance past unrelated stores...
588 if (--cnt < 0) break; // Caught in cycle or a complicated dance?
589
590 Node* prev = mem;
591 if (mem->is_Store()) {
592 Node* st_adr = mem->in(MemNode::Address);
593 intptr_t st_offset = 0;
594 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
595 if (st_base == NULL)
596 break; // inscrutable pointer
597
598 // For raw accesses it's not enough to prove that constant offsets don't intersect.
599 // We need the bases to be the equal in order for the offset check to make sense.
600 if ((adr_maybe_raw || check_if_adr_maybe_raw(st_adr)) && st_base != base) {
601 break;
602 }
603
604 if (st_offset != offset && st_offset != Type::OffsetBot) {
605 const int MAX_STORE = BytesPerLong;
606 if (st_offset >= offset + size_in_bytes ||
607 st_offset <= offset - MAX_STORE ||
608 st_offset <= offset - mem->as_Store()->memory_size()) {
609 // Success: The offsets are provably independent.
610 // (You may ask, why not just test st_offset != offset and be done?
611 // The answer is that stores of different sizes can co-exist
612 // in the same sequence of RawMem effects. We sometimes initialize
613 // a whole 'tile' of array elements with a single jint or jlong.)
614 mem = mem->in(MemNode::Memory);
615 continue; // (a) advance through independent store memory
616 }
617 }
618 if (st_base != base &&
619 detect_ptr_independence(base, alloc,
620 st_base,
621 AllocateNode::Ideal_allocation(st_base, phase),
622 phase)) {
623 // Success: The bases are provably independent.
624 mem = mem->in(MemNode::Memory);
625 continue; // (a) advance through independent store memory
626 }
627
628 // (b) At this point, if the bases or offsets do not agree, we lose,
629 // since we have not managed to prove 'this' and 'mem' independent.
630 if (st_base == base && st_offset == offset) {
631 return mem; // let caller handle steps (c), (d)
632 }
633
634 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
635 InitializeNode* st_init = mem->in(0)->as_Initialize();
636 AllocateNode* st_alloc = st_init->allocation();
637 if (st_alloc == NULL)
638 break; // something degenerated
639 bool known_identical = false;
640 bool known_independent = false;
641 if (alloc == st_alloc)
642 known_identical = true;
643 else if (alloc != NULL)
644 known_independent = true;
645 else if (all_controls_dominate(this, st_alloc))
646 known_independent = true;
647
648 if (known_independent) {
649 // The bases are provably independent: Either they are
650 // manifestly distinct allocations, or else the control
651 // of this load dominates the store's allocation.
652 int alias_idx = phase->C->get_alias_index(adr_type());
653 if (alias_idx == Compile::AliasIdxRaw) {
654 mem = st_alloc->in(TypeFunc::Memory);
655 } else {
656 mem = st_init->memory(alias_idx);
657 }
658 continue; // (a) advance through independent store memory
659 }
660
661 // (b) at this point, if we are not looking at a store initializing
662 // the same allocation we are loading from, we lose.
663 if (known_identical) {
664 // From caller, can_see_stored_value will consult find_captured_store.
665 return mem; // let caller handle steps (c), (d)
666 }
667
668 } else if (find_previous_arraycopy(phase, alloc, mem, false) != NULL) {
669 if (prev != mem) {
670 // Found an arraycopy but it doesn't affect that load
671 continue;
672 }
673 // Found an arraycopy that may affect that load
674 return mem;
675 } else if (addr_t != NULL && addr_t->is_known_instance_field()) {
676 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
677 if (mem->is_Proj() && mem->in(0)->is_Call()) {
678 // ArrayCopyNodes processed here as well.
679 CallNode *call = mem->in(0)->as_Call();
680 if (!call->may_modify(addr_t, phase)) {
681 mem = call->in(TypeFunc::Memory);
682 continue; // (a) advance through independent call memory
683 }
684 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) {
685 ArrayCopyNode* ac = NULL;
686 if (ArrayCopyNode::may_modify(addr_t, mem->in(0)->as_MemBar(), phase, ac)) {
687 break;
688 }
689 mem = mem->in(0)->in(TypeFunc::Memory);
690 continue; // (a) advance through independent MemBar memory
691 } else if (mem->is_ClearArray()) {
692 if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) {
693 // (the call updated 'mem' value)
694 continue; // (a) advance through independent allocation memory
695 } else {
696 // Can not bypass initialization of the instance
697 // we are looking for.
698 return mem;
699 }
700 } else if (mem->is_MergeMem()) {
701 int alias_idx = phase->C->get_alias_index(adr_type());
702 mem = mem->as_MergeMem()->memory_at(alias_idx);
703 continue; // (a) advance through independent MergeMem memory
704 }
705 }
706
707 // Unless there is an explicit 'continue', we must bail out here,
708 // because 'mem' is an inscrutable memory state (e.g., a call).
709 break;
710 }
711
712 return NULL; // bail out
713 }
714
715 //----------------------calculate_adr_type-------------------------------------
716 // Helper function. Notices when the given type of address hits top or bottom.
717 // Also, asserts a cross-check of the type against the expected address type.
718 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
719 if (t == Type::TOP) return NULL; // does not touch memory any more?
720 #ifdef PRODUCT
721 cross_check = NULL;
722 #else
723 if (!VerifyAliases || VMError::is_error_reported() || Node::in_dump()) cross_check = NULL;
724 #endif
725 const TypePtr* tp = t->isa_ptr();
726 if (tp == NULL) {
727 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
728 return TypePtr::BOTTOM; // touches lots of memory
729 } else {
730 #ifdef ASSERT
731 // %%%% [phh] We don't check the alias index if cross_check is
732 // TypeRawPtr::BOTTOM. Needs to be investigated.
733 if (cross_check != NULL &&
734 cross_check != TypePtr::BOTTOM &&
735 cross_check != TypeRawPtr::BOTTOM) {
736 // Recheck the alias index, to see if it has changed (due to a bug).
737 Compile* C = Compile::current();
738 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
739 "must stay in the original alias category");
740 // The type of the address must be contained in the adr_type,
741 // disregarding "null"-ness.
742 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
743 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
744 assert(cross_check->meet(tp_notnull) == cross_check->remove_speculative(),
745 "real address must not escape from expected memory type");
746 }
747 #endif
748 return tp;
749 }
750 }
751
752 //=============================================================================
753 // Should LoadNode::Ideal() attempt to remove control edges?
754 bool LoadNode::can_remove_control() const {
755 return true;
756 }
757 uint LoadNode::size_of() const { return sizeof(*this); }
758 uint LoadNode::cmp( const Node &n ) const
759 { return !Type::cmp( _type, ((LoadNode&)n)._type ); }
760 const Type *LoadNode::bottom_type() const { return _type; }
761 uint LoadNode::ideal_reg() const {
762 return _type->ideal_reg();
763 }
764
765 #ifndef PRODUCT
766 void LoadNode::dump_spec(outputStream *st) const {
767 MemNode::dump_spec(st);
768 if( !Verbose && !WizardMode ) {
769 // standard dump does this in Verbose and WizardMode
770 st->print(" #"); _type->dump_on(st);
771 }
772 if (!depends_only_on_test()) {
773 st->print(" (does not depend only on test)");
774 }
775 }
776 #endif
777
778 #ifdef ASSERT
779 //----------------------------is_immutable_value-------------------------------
780 // Helper function to allow a raw load without control edge for some cases
781 bool LoadNode::is_immutable_value(Node* adr) {
782 return (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() &&
783 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal &&
784 (adr->in(AddPNode::Offset)->find_intptr_t_con(-1) ==
785 in_bytes(JavaThread::osthread_offset())));
786 }
787 #endif
788
789 //----------------------------LoadNode::make-----------------------------------
790 // Polymorphic factory method:
791 Node *LoadNode::make(PhaseGVN& gvn, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt, MemOrd mo,
792 ControlDependency control_dependency, bool unaligned, bool mismatched) {
793 Compile* C = gvn.C;
794
795 // sanity check the alias category against the created node type
796 assert(!(adr_type->isa_oopptr() &&
797 adr_type->offset() == oopDesc::klass_offset_in_bytes()),
798 "use LoadKlassNode instead");
799 assert(!(adr_type->isa_aryptr() &&
800 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
801 "use LoadRangeNode instead");
802 // Check control edge of raw loads
803 assert( ctl != NULL || C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
804 // oop will be recorded in oop map if load crosses safepoint
805 rt->isa_oopptr() || is_immutable_value(adr),
806 "raw memory operations should have control edge");
807 LoadNode* load = NULL;
808 switch (bt) {
809 case T_BOOLEAN: load = new LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
810 case T_BYTE: load = new LoadBNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
811 case T_INT: load = new LoadINode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
812 case T_CHAR: load = new LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
813 case T_SHORT: load = new LoadSNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
814 case T_LONG: load = new LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency); break;
815 case T_FLOAT: load = new LoadFNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); break;
816 case T_DOUBLE: load = new LoadDNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); break;
817 case T_ADDRESS: load = new LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency); break;
818 case T_OBJECT:
819 #ifdef _LP64
820 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
821 load = new LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo, control_dependency);
822 } else
823 #endif
824 {
825 assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop");
826 load = new LoadPNode(ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency);
827 }
828 break;
829 default:
830 ShouldNotReachHere();
831 break;
832 }
833 assert(load != NULL, "LoadNode should have been created");
834 if (unaligned) {
835 load->set_unaligned_access();
836 }
837 if (mismatched) {
838 load->set_mismatched_access();
839 }
840 if (load->Opcode() == Op_LoadN) {
841 Node* ld = gvn.transform(load);
842 return new DecodeNNode(ld, ld->bottom_type()->make_ptr());
843 }
844
845 return load;
846 }
847
848 LoadLNode* LoadLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo,
849 ControlDependency control_dependency, bool unaligned, bool mismatched) {
850 bool require_atomic = true;
851 LoadLNode* load = new LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency, require_atomic);
852 if (unaligned) {
853 load->set_unaligned_access();
854 }
855 if (mismatched) {
856 load->set_mismatched_access();
857 }
858 return load;
859 }
860
861 LoadDNode* LoadDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo,
862 ControlDependency control_dependency, bool unaligned, bool mismatched) {
863 bool require_atomic = true;
864 LoadDNode* load = new LoadDNode(ctl, mem, adr, adr_type, rt, mo, control_dependency, require_atomic);
865 if (unaligned) {
866 load->set_unaligned_access();
867 }
868 if (mismatched) {
869 load->set_mismatched_access();
870 }
871 return load;
872 }
873
874
875
876 //------------------------------hash-------------------------------------------
877 uint LoadNode::hash() const {
878 // unroll addition of interesting fields
879 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
880 }
881
882 static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) {
883 if ((atp != NULL) && (atp->index() >= Compile::AliasIdxRaw)) {
884 bool non_volatile = (atp->field() != NULL) && !atp->field()->is_volatile();
885 bool is_stable_ary = FoldStableValues &&
886 (tp != NULL) && (tp->isa_aryptr() != NULL) &&
887 tp->isa_aryptr()->is_stable();
888
889 return (eliminate_boxing && non_volatile) || is_stable_ary;
890 }
891
892 return false;
893 }
894
895 // Is the value loaded previously stored by an arraycopy? If so return
896 // a load node that reads from the source array so we may be able to
897 // optimize out the ArrayCopy node later.
898 Node* LoadNode::can_see_arraycopy_value(Node* st, PhaseGVN* phase) const {
899 #if INCLUDE_ZGC
900 if (UseZGC) {
901 if (bottom_type()->make_oopptr() != NULL) {
902 return NULL;
903 }
904 }
905 #endif
906
907 Node* ld_adr = in(MemNode::Address);
908 intptr_t ld_off = 0;
909 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
910 Node* ac = find_previous_arraycopy(phase, ld_alloc, st, true);
911 if (ac != NULL) {
912 assert(ac->is_ArrayCopy(), "what kind of node can this be?");
913
914 Node* mem = ac->in(TypeFunc::Memory);
915 Node* ctl = ac->in(0);
916 Node* src = ac->in(ArrayCopyNode::Src);
917
918 if (!ac->as_ArrayCopy()->is_clonebasic() && !phase->type(src)->isa_aryptr()) {
919 return NULL;
920 }
921
922 LoadNode* ld = clone()->as_Load();
923 Node* addp = in(MemNode::Address)->clone();
924 if (ac->as_ArrayCopy()->is_clonebasic()) {
925 assert(ld_alloc != NULL, "need an alloc");
926 assert(addp->is_AddP(), "address must be addp");
927 assert(ac->in(ArrayCopyNode::Dest)->is_AddP(), "dest must be an address");
928 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
929 assert(bs->step_over_gc_barrier(addp->in(AddPNode::Base)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)->in(AddPNode::Base)), "strange pattern");
930 assert(bs->step_over_gc_barrier(addp->in(AddPNode::Address)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)->in(AddPNode::Address)), "strange pattern");
931 addp->set_req(AddPNode::Base, src->in(AddPNode::Base));
932 addp->set_req(AddPNode::Address, src->in(AddPNode::Address));
933 } else {
934 assert(ac->as_ArrayCopy()->is_arraycopy_validated() ||
935 ac->as_ArrayCopy()->is_copyof_validated() ||
936 ac->as_ArrayCopy()->is_copyofrange_validated(), "only supported cases");
937 assert(addp->in(AddPNode::Base) == addp->in(AddPNode::Address), "should be");
938 addp->set_req(AddPNode::Base, src);
939 addp->set_req(AddPNode::Address, src);
940
941 const TypeAryPtr* ary_t = phase->type(in(MemNode::Address))->isa_aryptr();
942 BasicType ary_elem = ary_t->klass()->as_array_klass()->element_type()->basic_type();
943 uint header = arrayOopDesc::base_offset_in_bytes(ary_elem);
944 uint shift = exact_log2(type2aelembytes(ary_elem));
945
946 Node* diff = phase->transform(new SubINode(ac->in(ArrayCopyNode::SrcPos), ac->in(ArrayCopyNode::DestPos)));
947 #ifdef _LP64
948 diff = phase->transform(new ConvI2LNode(diff));
949 #endif
950 diff = phase->transform(new LShiftXNode(diff, phase->intcon(shift)));
951
952 Node* offset = phase->transform(new AddXNode(addp->in(AddPNode::Offset), diff));
953 addp->set_req(AddPNode::Offset, offset);
954 }
955 addp = phase->transform(addp);
956 #ifdef ASSERT
957 const TypePtr* adr_type = phase->type(addp)->is_ptr();
958 ld->_adr_type = adr_type;
959 #endif
960 ld->set_req(MemNode::Address, addp);
961 ld->set_req(0, ctl);
962 ld->set_req(MemNode::Memory, mem);
963 // load depends on the tests that validate the arraycopy
964 ld->_control_dependency = Pinned;
965 return ld;
966 }
967 return NULL;
968 }
969
970
971 //---------------------------can_see_stored_value------------------------------
972 // This routine exists to make sure this set of tests is done the same
973 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
974 // will change the graph shape in a way which makes memory alive twice at the
975 // same time (uses the Oracle model of aliasing), then some
976 // LoadXNode::Identity will fold things back to the equivalence-class model
977 // of aliasing.
978 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const {
979 Node* ld_adr = in(MemNode::Address);
980 intptr_t ld_off = 0;
981 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
982 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
983 Compile::AliasType* atp = (tp != NULL) ? phase->C->alias_type(tp) : NULL;
984 // This is more general than load from boxing objects.
985 if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) {
986 uint alias_idx = atp->index();
987 bool final = !atp->is_rewritable();
988 Node* result = NULL;
989 Node* current = st;
990 // Skip through chains of MemBarNodes checking the MergeMems for
991 // new states for the slice of this load. Stop once any other
992 // kind of node is encountered. Loads from final memory can skip
993 // through any kind of MemBar but normal loads shouldn't skip
994 // through MemBarAcquire since the could allow them to move out of
995 // a synchronized region.
996 while (current->is_Proj()) {
997 int opc = current->in(0)->Opcode();
998 if ((final && (opc == Op_MemBarAcquire ||
999 opc == Op_MemBarAcquireLock ||
1000 opc == Op_LoadFence)) ||
1001 opc == Op_MemBarRelease ||
1002 opc == Op_StoreFence ||
1003 opc == Op_MemBarReleaseLock ||
1004 opc == Op_MemBarStoreStore ||
1005 opc == Op_MemBarCPUOrder) {
1006 Node* mem = current->in(0)->in(TypeFunc::Memory);
1007 if (mem->is_MergeMem()) {
1008 MergeMemNode* merge = mem->as_MergeMem();
1009 Node* new_st = merge->memory_at(alias_idx);
1010 if (new_st == merge->base_memory()) {
1011 // Keep searching
1012 current = new_st;
1013 continue;
1014 }
1015 // Save the new memory state for the slice and fall through
1016 // to exit.
1017 result = new_st;
1018 }
1019 }
1020 break;
1021 }
1022 if (result != NULL) {
1023 st = result;
1024 }
1025 }
1026
1027 // Loop around twice in the case Load -> Initialize -> Store.
1028 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
1029 for (int trip = 0; trip <= 1; trip++) {
1030
1031 if (st->is_Store()) {
1032 Node* st_adr = st->in(MemNode::Address);
1033 if (!phase->eqv(st_adr, ld_adr)) {
1034 // Try harder before giving up... Match raw and non-raw pointers.
1035 intptr_t st_off = 0;
1036 AllocateNode* alloc = AllocateNode::Ideal_allocation(st_adr, phase, st_off);
1037 if (alloc == NULL) return NULL;
1038 if (alloc != ld_alloc) return NULL;
1039 if (ld_off != st_off) return NULL;
1040 // At this point we have proven something like this setup:
1041 // A = Allocate(...)
1042 // L = LoadQ(, AddP(CastPP(, A.Parm),, #Off))
1043 // S = StoreQ(, AddP(, A.Parm , #Off), V)
1044 // (Actually, we haven't yet proven the Q's are the same.)
1045 // In other words, we are loading from a casted version of
1046 // the same pointer-and-offset that we stored to.
1047 // Thus, we are able to replace L by V.
1048 }
1049 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
1050 if (store_Opcode() != st->Opcode())
1051 return NULL;
1052 return st->in(MemNode::ValueIn);
1053 }
1054
1055 // A load from a freshly-created object always returns zero.
1056 // (This can happen after LoadNode::Ideal resets the load's memory input
1057 // to find_captured_store, which returned InitializeNode::zero_memory.)
1058 if (st->is_Proj() && st->in(0)->is_Allocate() &&
1059 (st->in(0) == ld_alloc) &&
1060 (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) {
1061 // return a zero value for the load's basic type
1062 // (This is one of the few places where a generic PhaseTransform
1063 // can create new nodes. Think of it as lazily manifesting
1064 // virtually pre-existing constants.)
1065 return phase->zerocon(memory_type());
1066 }
1067
1068 // A load from an initialization barrier can match a captured store.
1069 if (st->is_Proj() && st->in(0)->is_Initialize()) {
1070 InitializeNode* init = st->in(0)->as_Initialize();
1071 AllocateNode* alloc = init->allocation();
1072 if ((alloc != NULL) && (alloc == ld_alloc)) {
1073 // examine a captured store value
1074 st = init->find_captured_store(ld_off, memory_size(), phase);
1075 if (st != NULL) {
1076 continue; // take one more trip around
1077 }
1078 }
1079 }
1080
1081 // Load boxed value from result of valueOf() call is input parameter.
1082 if (this->is_Load() && ld_adr->is_AddP() &&
1083 (tp != NULL) && tp->is_ptr_to_boxed_value()) {
1084 intptr_t ignore = 0;
1085 Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore);
1086 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1087 base = bs->step_over_gc_barrier(base);
1088 if (base != NULL && base->is_Proj() &&
1089 base->as_Proj()->_con == TypeFunc::Parms &&
1090 base->in(0)->is_CallStaticJava() &&
1091 base->in(0)->as_CallStaticJava()->is_boxing_method()) {
1092 return base->in(0)->in(TypeFunc::Parms);
1093 }
1094 }
1095
1096 break;
1097 }
1098
1099 return NULL;
1100 }
1101
1102 //----------------------is_instance_field_load_with_local_phi------------------
1103 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
1104 if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl &&
1105 in(Address)->is_AddP() ) {
1106 const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr();
1107 // Only instances and boxed values.
1108 if( t_oop != NULL &&
1109 (t_oop->is_ptr_to_boxed_value() ||
1110 t_oop->is_known_instance_field()) &&
1111 t_oop->offset() != Type::OffsetBot &&
1112 t_oop->offset() != Type::OffsetTop) {
1113 return true;
1114 }
1115 }
1116 return false;
1117 }
1118
1119 //------------------------------Identity---------------------------------------
1120 // Loads are identity if previous store is to same address
1121 Node* LoadNode::Identity(PhaseGVN* phase) {
1122 // If the previous store-maker is the right kind of Store, and the store is
1123 // to the same address, then we are equal to the value stored.
1124 Node* mem = in(Memory);
1125 Node* value = can_see_stored_value(mem, phase);
1126 if( value ) {
1127 // byte, short & char stores truncate naturally.
1128 // A load has to load the truncated value which requires
1129 // some sort of masking operation and that requires an
1130 // Ideal call instead of an Identity call.
1131 if (memory_size() < BytesPerInt) {
1132 // If the input to the store does not fit with the load's result type,
1133 // it must be truncated via an Ideal call.
1134 if (!phase->type(value)->higher_equal(phase->type(this)))
1135 return this;
1136 }
1137 // (This works even when value is a Con, but LoadNode::Value
1138 // usually runs first, producing the singleton type of the Con.)
1139 return value;
1140 }
1141
1142 // Search for an existing data phi which was generated before for the same
1143 // instance's field to avoid infinite generation of phis in a loop.
1144 Node *region = mem->in(0);
1145 if (is_instance_field_load_with_local_phi(region)) {
1146 const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr();
1147 int this_index = phase->C->get_alias_index(addr_t);
1148 int this_offset = addr_t->offset();
1149 int this_iid = addr_t->instance_id();
1150 if (!addr_t->is_known_instance() &&
1151 addr_t->is_ptr_to_boxed_value()) {
1152 // Use _idx of address base (could be Phi node) for boxed values.
1153 intptr_t ignore = 0;
1154 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1155 if (base == NULL) {
1156 return this;
1157 }
1158 this_iid = base->_idx;
1159 }
1160 const Type* this_type = bottom_type();
1161 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1162 Node* phi = region->fast_out(i);
1163 if (phi->is_Phi() && phi != mem &&
1164 phi->as_Phi()->is_same_inst_field(this_type, (int)mem->_idx, this_iid, this_index, this_offset)) {
1165 return phi;
1166 }
1167 }
1168 }
1169
1170 return this;
1171 }
1172
1173 // Construct an equivalent unsigned load.
1174 Node* LoadNode::convert_to_unsigned_load(PhaseGVN& gvn) {
1175 BasicType bt = T_ILLEGAL;
1176 const Type* rt = NULL;
1177 switch (Opcode()) {
1178 case Op_LoadUB: return this;
1179 case Op_LoadUS: return this;
1180 case Op_LoadB: bt = T_BOOLEAN; rt = TypeInt::UBYTE; break;
1181 case Op_LoadS: bt = T_CHAR; rt = TypeInt::CHAR; break;
1182 default:
1183 assert(false, "no unsigned variant: %s", Name());
1184 return NULL;
1185 }
1186 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1187 raw_adr_type(), rt, bt, _mo, _control_dependency,
1188 is_unaligned_access(), is_mismatched_access());
1189 }
1190
1191 // Construct an equivalent signed load.
1192 Node* LoadNode::convert_to_signed_load(PhaseGVN& gvn) {
1193 BasicType bt = T_ILLEGAL;
1194 const Type* rt = NULL;
1195 switch (Opcode()) {
1196 case Op_LoadUB: bt = T_BYTE; rt = TypeInt::BYTE; break;
1197 case Op_LoadUS: bt = T_SHORT; rt = TypeInt::SHORT; break;
1198 case Op_LoadB: // fall through
1199 case Op_LoadS: // fall through
1200 case Op_LoadI: // fall through
1201 case Op_LoadL: return this;
1202 default:
1203 assert(false, "no signed variant: %s", Name());
1204 return NULL;
1205 }
1206 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1207 raw_adr_type(), rt, bt, _mo, _control_dependency,
1208 is_unaligned_access(), is_mismatched_access());
1209 }
1210
1211 // We're loading from an object which has autobox behaviour.
1212 // If this object is result of a valueOf call we'll have a phi
1213 // merging a newly allocated object and a load from the cache.
1214 // We want to replace this load with the original incoming
1215 // argument to the valueOf call.
1216 Node* LoadNode::eliminate_autobox(PhaseGVN* phase) {
1217 assert(phase->C->eliminate_boxing(), "sanity");
1218 intptr_t ignore = 0;
1219 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1220 if ((base == NULL) || base->is_Phi()) {
1221 // Push the loads from the phi that comes from valueOf up
1222 // through it to allow elimination of the loads and the recovery
1223 // of the original value. It is done in split_through_phi().
1224 return NULL;
1225 } else if (base->is_Load() ||
1226 (base->is_DecodeN() && base->in(1)->is_Load())) {
1227 // Eliminate the load of boxed value for integer types from the cache
1228 // array by deriving the value from the index into the array.
1229 // Capture the offset of the load and then reverse the computation.
1230
1231 // Get LoadN node which loads a boxing object from 'cache' array.
1232 if (base->is_DecodeN()) {
1233 base = base->in(1);
1234 }
1235 if (!base->in(Address)->is_AddP()) {
1236 return NULL; // Complex address
1237 }
1238 AddPNode* address = base->in(Address)->as_AddP();
1239 Node* cache_base = address->in(AddPNode::Base);
1240 if ((cache_base != NULL) && cache_base->is_DecodeN()) {
1241 // Get ConP node which is static 'cache' field.
1242 cache_base = cache_base->in(1);
1243 }
1244 if ((cache_base != NULL) && cache_base->is_Con()) {
1245 const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr();
1246 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1247 Node* elements[4];
1248 int shift = exact_log2(type2aelembytes(T_OBJECT));
1249 int count = address->unpack_offsets(elements, ARRAY_SIZE(elements));
1250 if (count > 0 && elements[0]->is_Con() &&
1251 (count == 1 ||
1252 (count == 2 && elements[1]->Opcode() == Op_LShiftX &&
1253 elements[1]->in(2) == phase->intcon(shift)))) {
1254 ciObjArray* array = base_type->const_oop()->as_obj_array();
1255 // Fetch the box object cache[0] at the base of the array and get its value
1256 ciInstance* box = array->obj_at(0)->as_instance();
1257 ciInstanceKlass* ik = box->klass()->as_instance_klass();
1258 assert(ik->is_box_klass(), "sanity");
1259 assert(ik->nof_nonstatic_fields() == 1, "change following code");
1260 if (ik->nof_nonstatic_fields() == 1) {
1261 // This should be true nonstatic_field_at requires calling
1262 // nof_nonstatic_fields so check it anyway
1263 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1264 BasicType bt = c.basic_type();
1265 // Only integer types have boxing cache.
1266 assert(bt == T_BOOLEAN || bt == T_CHAR ||
1267 bt == T_BYTE || bt == T_SHORT ||
1268 bt == T_INT || bt == T_LONG, "wrong type = %s", type2name(bt));
1269 jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int();
1270 if (cache_low != (int)cache_low) {
1271 return NULL; // should not happen since cache is array indexed by value
1272 }
1273 jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift);
1274 if (offset != (int)offset) {
1275 return NULL; // should not happen since cache is array indexed by value
1276 }
1277 // Add up all the offsets making of the address of the load
1278 Node* result = elements[0];
1279 for (int i = 1; i < count; i++) {
1280 result = phase->transform(new AddXNode(result, elements[i]));
1281 }
1282 // Remove the constant offset from the address and then
1283 result = phase->transform(new AddXNode(result, phase->MakeConX(-(int)offset)));
1284 // remove the scaling of the offset to recover the original index.
1285 if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) {
1286 // Peel the shift off directly but wrap it in a dummy node
1287 // since Ideal can't return existing nodes
1288 result = new RShiftXNode(result->in(1), phase->intcon(0));
1289 } else if (result->is_Add() && result->in(2)->is_Con() &&
1290 result->in(1)->Opcode() == Op_LShiftX &&
1291 result->in(1)->in(2) == phase->intcon(shift)) {
1292 // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z)
1293 // but for boxing cache access we know that X<<Z will not overflow
1294 // (there is range check) so we do this optimizatrion by hand here.
1295 Node* add_con = new RShiftXNode(result->in(2), phase->intcon(shift));
1296 result = new AddXNode(result->in(1)->in(1), phase->transform(add_con));
1297 } else {
1298 result = new RShiftXNode(result, phase->intcon(shift));
1299 }
1300 #ifdef _LP64
1301 if (bt != T_LONG) {
1302 result = new ConvL2INode(phase->transform(result));
1303 }
1304 #else
1305 if (bt == T_LONG) {
1306 result = new ConvI2LNode(phase->transform(result));
1307 }
1308 #endif
1309 // Boxing/unboxing can be done from signed & unsigned loads (e.g. LoadUB -> ... -> LoadB pair).
1310 // Need to preserve unboxing load type if it is unsigned.
1311 switch(this->Opcode()) {
1312 case Op_LoadUB:
1313 result = new AndINode(phase->transform(result), phase->intcon(0xFF));
1314 break;
1315 case Op_LoadUS:
1316 result = new AndINode(phase->transform(result), phase->intcon(0xFFFF));
1317 break;
1318 }
1319 return result;
1320 }
1321 }
1322 }
1323 }
1324 }
1325 return NULL;
1326 }
1327
1328 static bool stable_phi(PhiNode* phi, PhaseGVN *phase) {
1329 Node* region = phi->in(0);
1330 if (region == NULL) {
1331 return false; // Wait stable graph
1332 }
1333 uint cnt = phi->req();
1334 for (uint i = 1; i < cnt; i++) {
1335 Node* rc = region->in(i);
1336 if (rc == NULL || phase->type(rc) == Type::TOP)
1337 return false; // Wait stable graph
1338 Node* in = phi->in(i);
1339 if (in == NULL || phase->type(in) == Type::TOP)
1340 return false; // Wait stable graph
1341 }
1342 return true;
1343 }
1344 //------------------------------split_through_phi------------------------------
1345 // Split instance or boxed field load through Phi.
1346 Node *LoadNode::split_through_phi(PhaseGVN *phase) {
1347 Node* mem = in(Memory);
1348 Node* address = in(Address);
1349 const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr();
1350
1351 assert((t_oop != NULL) &&
1352 (t_oop->is_known_instance_field() ||
1353 t_oop->is_ptr_to_boxed_value()), "invalide conditions");
1354
1355 Compile* C = phase->C;
1356 intptr_t ignore = 0;
1357 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1358 bool base_is_phi = (base != NULL) && base->is_Phi();
1359 bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() &&
1360 (base != NULL) && (base == address->in(AddPNode::Base)) &&
1361 phase->type(base)->higher_equal(TypePtr::NOTNULL);
1362
1363 if (!((mem->is_Phi() || base_is_phi) &&
1364 (load_boxed_values || t_oop->is_known_instance_field()))) {
1365 return NULL; // memory is not Phi
1366 }
1367
1368 if (mem->is_Phi()) {
1369 if (!stable_phi(mem->as_Phi(), phase)) {
1370 return NULL; // Wait stable graph
1371 }
1372 uint cnt = mem->req();
1373 // Check for loop invariant memory.
1374 if (cnt == 3) {
1375 for (uint i = 1; i < cnt; i++) {
1376 Node* in = mem->in(i);
1377 Node* m = optimize_memory_chain(in, t_oop, this, phase);
1378 if (m == mem) {
1379 set_req(Memory, mem->in(cnt - i));
1380 return this; // made change
1381 }
1382 }
1383 }
1384 }
1385 if (base_is_phi) {
1386 if (!stable_phi(base->as_Phi(), phase)) {
1387 return NULL; // Wait stable graph
1388 }
1389 uint cnt = base->req();
1390 // Check for loop invariant memory.
1391 if (cnt == 3) {
1392 for (uint i = 1; i < cnt; i++) {
1393 if (base->in(i) == base) {
1394 return NULL; // Wait stable graph
1395 }
1396 }
1397 }
1398 }
1399
1400 bool load_boxed_phi = load_boxed_values && base_is_phi && (base->in(0) == mem->in(0));
1401
1402 // Split through Phi (see original code in loopopts.cpp).
1403 assert(C->have_alias_type(t_oop), "instance should have alias type");
1404
1405 // Do nothing here if Identity will find a value
1406 // (to avoid infinite chain of value phis generation).
1407 if (!phase->eqv(this, this->Identity(phase)))
1408 return NULL;
1409
1410 // Select Region to split through.
1411 Node* region;
1412 if (!base_is_phi) {
1413 assert(mem->is_Phi(), "sanity");
1414 region = mem->in(0);
1415 // Skip if the region dominates some control edge of the address.
1416 if (!MemNode::all_controls_dominate(address, region))
1417 return NULL;
1418 } else if (!mem->is_Phi()) {
1419 assert(base_is_phi, "sanity");
1420 region = base->in(0);
1421 // Skip if the region dominates some control edge of the memory.
1422 if (!MemNode::all_controls_dominate(mem, region))
1423 return NULL;
1424 } else if (base->in(0) != mem->in(0)) {
1425 assert(base_is_phi && mem->is_Phi(), "sanity");
1426 if (MemNode::all_controls_dominate(mem, base->in(0))) {
1427 region = base->in(0);
1428 } else if (MemNode::all_controls_dominate(address, mem->in(0))) {
1429 region = mem->in(0);
1430 } else {
1431 return NULL; // complex graph
1432 }
1433 } else {
1434 assert(base->in(0) == mem->in(0), "sanity");
1435 region = mem->in(0);
1436 }
1437
1438 const Type* this_type = this->bottom_type();
1439 int this_index = C->get_alias_index(t_oop);
1440 int this_offset = t_oop->offset();
1441 int this_iid = t_oop->instance_id();
1442 if (!t_oop->is_known_instance() && load_boxed_values) {
1443 // Use _idx of address base for boxed values.
1444 this_iid = base->_idx;
1445 }
1446 PhaseIterGVN* igvn = phase->is_IterGVN();
1447 Node* phi = new PhiNode(region, this_type, NULL, mem->_idx, this_iid, this_index, this_offset);
1448 for (uint i = 1; i < region->req(); i++) {
1449 Node* x;
1450 Node* the_clone = NULL;
1451 if (region->in(i) == C->top()) {
1452 x = C->top(); // Dead path? Use a dead data op
1453 } else {
1454 x = this->clone(); // Else clone up the data op
1455 the_clone = x; // Remember for possible deletion.
1456 // Alter data node to use pre-phi inputs
1457 if (this->in(0) == region) {
1458 x->set_req(0, region->in(i));
1459 } else {
1460 x->set_req(0, NULL);
1461 }
1462 if (mem->is_Phi() && (mem->in(0) == region)) {
1463 x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone.
1464 }
1465 if (address->is_Phi() && address->in(0) == region) {
1466 x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone
1467 }
1468 if (base_is_phi && (base->in(0) == region)) {
1469 Node* base_x = base->in(i); // Clone address for loads from boxed objects.
1470 Node* adr_x = phase->transform(new AddPNode(base_x,base_x,address->in(AddPNode::Offset)));
1471 x->set_req(Address, adr_x);
1472 }
1473 }
1474 // Check for a 'win' on some paths
1475 const Type *t = x->Value(igvn);
1476
1477 bool singleton = t->singleton();
1478
1479 // See comments in PhaseIdealLoop::split_thru_phi().
1480 if (singleton && t == Type::TOP) {
1481 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1482 }
1483
1484 if (singleton) {
1485 x = igvn->makecon(t);
1486 } else {
1487 // We now call Identity to try to simplify the cloned node.
1488 // Note that some Identity methods call phase->type(this).
1489 // Make sure that the type array is big enough for
1490 // our new node, even though we may throw the node away.
1491 // (This tweaking with igvn only works because x is a new node.)
1492 igvn->set_type(x, t);
1493 // If x is a TypeNode, capture any more-precise type permanently into Node
1494 // otherwise it will be not updated during igvn->transform since
1495 // igvn->type(x) is set to x->Value() already.
1496 x->raise_bottom_type(t);
1497 Node *y = x->Identity(igvn);
1498 if (y != x) {
1499 x = y;
1500 } else {
1501 y = igvn->hash_find_insert(x);
1502 if (y) {
1503 x = y;
1504 } else {
1505 // Else x is a new node we are keeping
1506 // We do not need register_new_node_with_optimizer
1507 // because set_type has already been called.
1508 igvn->_worklist.push(x);
1509 }
1510 }
1511 }
1512 if (x != the_clone && the_clone != NULL) {
1513 igvn->remove_dead_node(the_clone);
1514 }
1515 phi->set_req(i, x);
1516 }
1517 // Record Phi
1518 igvn->register_new_node_with_optimizer(phi);
1519 return phi;
1520 }
1521
1522 //------------------------------Ideal------------------------------------------
1523 // If the load is from Field memory and the pointer is non-null, it might be possible to
1524 // zero out the control input.
1525 // If the offset is constant and the base is an object allocation,
1526 // try to hook me up to the exact initializing store.
1527 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1528 Node* p = MemNode::Ideal_common(phase, can_reshape);
1529 if (p) return (p == NodeSentinel) ? NULL : p;
1530
1531 Node* ctrl = in(MemNode::Control);
1532 Node* address = in(MemNode::Address);
1533 bool progress = false;
1534
1535 // Skip up past a SafePoint control. Cannot do this for Stores because
1536 // pointer stores & cardmarks must stay on the same side of a SafePoint.
1537 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint &&
1538 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw ) {
1539 ctrl = ctrl->in(0);
1540 set_req(MemNode::Control,ctrl);
1541 progress = true;
1542 }
1543
1544 intptr_t ignore = 0;
1545 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1546 if (base != NULL
1547 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
1548 // Check for useless control edge in some common special cases
1549 if (in(MemNode::Control) != NULL
1550 && can_remove_control()
1551 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1552 && all_controls_dominate(base, phase->C->start())) {
1553 // A method-invariant, non-null address (constant or 'this' argument).
1554 set_req(MemNode::Control, NULL);
1555 progress = true;
1556 }
1557 }
1558
1559 Node* mem = in(MemNode::Memory);
1560 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1561
1562 if (can_reshape && (addr_t != NULL)) {
1563 // try to optimize our memory input
1564 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase);
1565 if (opt_mem != mem) {
1566 set_req(MemNode::Memory, opt_mem);
1567 if (phase->type( opt_mem ) == Type::TOP) return NULL;
1568 return this;
1569 }
1570 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1571 if ((t_oop != NULL) &&
1572 (t_oop->is_known_instance_field() ||
1573 t_oop->is_ptr_to_boxed_value())) {
1574 PhaseIterGVN *igvn = phase->is_IterGVN();
1575 if (igvn != NULL && igvn->_worklist.member(opt_mem)) {
1576 // Delay this transformation until memory Phi is processed.
1577 phase->is_IterGVN()->_worklist.push(this);
1578 return NULL;
1579 }
1580 // Split instance field load through Phi.
1581 Node* result = split_through_phi(phase);
1582 if (result != NULL) return result;
1583
1584 if (t_oop->is_ptr_to_boxed_value()) {
1585 Node* result = eliminate_autobox(phase);
1586 if (result != NULL) return result;
1587 }
1588 }
1589 }
1590
1591 // Is there a dominating load that loads the same value? Leave
1592 // anything that is not a load of a field/array element (like
1593 // barriers etc.) alone
1594 if (in(0) != NULL && !adr_type()->isa_rawptr() && can_reshape) {
1595 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) {
1596 Node *use = mem->fast_out(i);
1597 if (use != this &&
1598 use->Opcode() == Opcode() &&
1599 use->in(0) != NULL &&
1600 use->in(0) != in(0) &&
1601 use->in(Address) == in(Address)) {
1602 Node* ctl = in(0);
1603 for (int i = 0; i < 10 && ctl != NULL; i++) {
1604 ctl = IfNode::up_one_dom(ctl);
1605 if (ctl == use->in(0)) {
1606 set_req(0, use->in(0));
1607 return this;
1608 }
1609 }
1610 }
1611 }
1612 }
1613
1614 // Check for prior store with a different base or offset; make Load
1615 // independent. Skip through any number of them. Bail out if the stores
1616 // are in an endless dead cycle and report no progress. This is a key
1617 // transform for Reflection. However, if after skipping through the Stores
1618 // we can't then fold up against a prior store do NOT do the transform as
1619 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
1620 // array memory alive twice: once for the hoisted Load and again after the
1621 // bypassed Store. This situation only works if EVERYBODY who does
1622 // anti-dependence work knows how to bypass. I.e. we need all
1623 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
1624 // the alias index stuff. So instead, peek through Stores and IFF we can
1625 // fold up, do so.
1626 Node* prev_mem = find_previous_store(phase);
1627 if (prev_mem != NULL) {
1628 Node* value = can_see_arraycopy_value(prev_mem, phase);
1629 if (value != NULL) {
1630 return value;
1631 }
1632 }
1633 // Steps (a), (b): Walk past independent stores to find an exact match.
1634 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) {
1635 // (c) See if we can fold up on the spot, but don't fold up here.
1636 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
1637 // just return a prior value, which is done by Identity calls.
1638 if (can_see_stored_value(prev_mem, phase)) {
1639 // Make ready for step (d):
1640 set_req(MemNode::Memory, prev_mem);
1641 return this;
1642 }
1643 }
1644
1645 return progress ? this : NULL;
1646 }
1647
1648 // Helper to recognize certain Klass fields which are invariant across
1649 // some group of array types (e.g., int[] or all T[] where T < Object).
1650 const Type*
1651 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1652 ciKlass* klass) const {
1653 if (tkls->offset() == in_bytes(Klass::modifier_flags_offset())) {
1654 // The field is Klass::_modifier_flags. Return its (constant) value.
1655 // (Folds up the 2nd indirection in aClassConstant.getModifiers().)
1656 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags");
1657 return TypeInt::make(klass->modifier_flags());
1658 }
1659 if (tkls->offset() == in_bytes(Klass::access_flags_offset())) {
1660 // The field is Klass::_access_flags. Return its (constant) value.
1661 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1662 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags");
1663 return TypeInt::make(klass->access_flags());
1664 }
1665 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) {
1666 // The field is Klass::_layout_helper. Return its constant value if known.
1667 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper");
1668 return TypeInt::make(klass->layout_helper());
1669 }
1670
1671 // No match.
1672 return NULL;
1673 }
1674
1675 //------------------------------Value-----------------------------------------
1676 const Type* LoadNode::Value(PhaseGVN* phase) const {
1677 // Either input is TOP ==> the result is TOP
1678 Node* mem = in(MemNode::Memory);
1679 const Type *t1 = phase->type(mem);
1680 if (t1 == Type::TOP) return Type::TOP;
1681 Node* adr = in(MemNode::Address);
1682 const TypePtr* tp = phase->type(adr)->isa_ptr();
1683 if (tp == NULL || tp->empty()) return Type::TOP;
1684 int off = tp->offset();
1685 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
1686 Compile* C = phase->C;
1687
1688 // Try to guess loaded type from pointer type
1689 if (tp->isa_aryptr()) {
1690 const TypeAryPtr* ary = tp->is_aryptr();
1691 const Type* t = ary->elem();
1692
1693 // Determine whether the reference is beyond the header or not, by comparing
1694 // the offset against the offset of the start of the array's data.
1695 // Different array types begin at slightly different offsets (12 vs. 16).
1696 // We choose T_BYTE as an example base type that is least restrictive
1697 // as to alignment, which will therefore produce the smallest
1698 // possible base offset.
1699 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
1700 const bool off_beyond_header = (off >= min_base_off);
1701
1702 // Try to constant-fold a stable array element.
1703 if (FoldStableValues && !is_mismatched_access() && ary->is_stable()) {
1704 // Make sure the reference is not into the header and the offset is constant
1705 ciObject* aobj = ary->const_oop();
1706 if (aobj != NULL && off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) {
1707 int stable_dimension = (ary->stable_dimension() > 0 ? ary->stable_dimension() - 1 : 0);
1708 const Type* con_type = Type::make_constant_from_array_element(aobj->as_array(), off,
1709 stable_dimension,
1710 memory_type(), is_unsigned());
1711 if (con_type != NULL) {
1712 return con_type;
1713 }
1714 }
1715 }
1716
1717 // Don't do this for integer types. There is only potential profit if
1718 // the element type t is lower than _type; that is, for int types, if _type is
1719 // more restrictive than t. This only happens here if one is short and the other
1720 // char (both 16 bits), and in those cases we've made an intentional decision
1721 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
1722 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
1723 //
1724 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
1725 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
1726 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
1727 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
1728 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
1729 // In fact, that could have been the original type of p1, and p1 could have
1730 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
1731 // expression (LShiftL quux 3) independently optimized to the constant 8.
1732 if ((t->isa_int() == NULL) && (t->isa_long() == NULL)
1733 && (_type->isa_vect() == NULL)
1734 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
1735 // t might actually be lower than _type, if _type is a unique
1736 // concrete subclass of abstract class t.
1737 if (off_beyond_header) { // is the offset beyond the header?
1738 const Type* jt = t->join_speculative(_type);
1739 // In any case, do not allow the join, per se, to empty out the type.
1740 if (jt->empty() && !t->empty()) {
1741 // This can happen if a interface-typed array narrows to a class type.
1742 jt = _type;
1743 }
1744 #ifdef ASSERT
1745 if (phase->C->eliminate_boxing() && adr->is_AddP()) {
1746 // The pointers in the autobox arrays are always non-null
1747 Node* base = adr->in(AddPNode::Base);
1748 if ((base != NULL) && base->is_DecodeN()) {
1749 // Get LoadN node which loads IntegerCache.cache field
1750 base = base->in(1);
1751 }
1752 if ((base != NULL) && base->is_Con()) {
1753 const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr();
1754 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1755 // It could be narrow oop
1756 assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity");
1757 }
1758 }
1759 }
1760 #endif
1761 return jt;
1762 }
1763 }
1764 } else if (tp->base() == Type::InstPtr) {
1765 assert( off != Type::OffsetBot ||
1766 // arrays can be cast to Objects
1767 tp->is_oopptr()->klass()->is_java_lang_Object() ||
1768 // unsafe field access may not have a constant offset
1769 C->has_unsafe_access(),
1770 "Field accesses must be precise" );
1771 // For oop loads, we expect the _type to be precise.
1772
1773 // Optimize loads from constant fields.
1774 const TypeInstPtr* tinst = tp->is_instptr();
1775 ciObject* const_oop = tinst->const_oop();
1776 if (!is_mismatched_access() && off != Type::OffsetBot && const_oop != NULL && const_oop->is_instance()) {
1777 const Type* con_type = Type::make_constant_from_field(const_oop->as_instance(), off, is_unsigned(), memory_type());
1778 if (con_type != NULL) {
1779 return con_type;
1780 }
1781 }
1782 } else if (tp->base() == Type::KlassPtr) {
1783 assert( off != Type::OffsetBot ||
1784 // arrays can be cast to Objects
1785 tp->is_klassptr()->klass()->is_java_lang_Object() ||
1786 // also allow array-loading from the primary supertype
1787 // array during subtype checks
1788 Opcode() == Op_LoadKlass,
1789 "Field accesses must be precise" );
1790 // For klass/static loads, we expect the _type to be precise
1791 } else if (tp->base() == Type::RawPtr && adr->is_Load() && off == 0) {
1792 /* With mirrors being an indirect in the Klass*
1793 * the VM is now using two loads. LoadKlass(LoadP(LoadP(Klass, mirror_offset), zero_offset))
1794 * The LoadP from the Klass has a RawPtr type (see LibraryCallKit::load_mirror_from_klass).
1795 *
1796 * So check the type and klass of the node before the LoadP.
1797 */
1798 Node* adr2 = adr->in(MemNode::Address);
1799 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
1800 if (tkls != NULL && !StressReflectiveCode) {
1801 ciKlass* klass = tkls->klass();
1802 if (klass->is_loaded() && tkls->klass_is_exact() && tkls->offset() == in_bytes(Klass::java_mirror_offset())) {
1803 assert(adr->Opcode() == Op_LoadP, "must load an oop from _java_mirror");
1804 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
1805 return TypeInstPtr::make(klass->java_mirror());
1806 }
1807 }
1808 }
1809
1810 const TypeKlassPtr *tkls = tp->isa_klassptr();
1811 if (tkls != NULL && !StressReflectiveCode) {
1812 ciKlass* klass = tkls->klass();
1813 if (klass->is_loaded() && tkls->klass_is_exact()) {
1814 // We are loading a field from a Klass metaobject whose identity
1815 // is known at compile time (the type is "exact" or "precise").
1816 // Check for fields we know are maintained as constants by the VM.
1817 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) {
1818 // The field is Klass::_super_check_offset. Return its (constant) value.
1819 // (Folds up type checking code.)
1820 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
1821 return TypeInt::make(klass->super_check_offset());
1822 }
1823 // Compute index into primary_supers array
1824 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1825 // Check for overflowing; use unsigned compare to handle the negative case.
1826 if( depth < ciKlass::primary_super_limit() ) {
1827 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1828 // (Folds up type checking code.)
1829 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1830 ciKlass *ss = klass->super_of_depth(depth);
1831 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1832 }
1833 const Type* aift = load_array_final_field(tkls, klass);
1834 if (aift != NULL) return aift;
1835 }
1836
1837 // We can still check if we are loading from the primary_supers array at a
1838 // shallow enough depth. Even though the klass is not exact, entries less
1839 // than or equal to its super depth are correct.
1840 if (klass->is_loaded() ) {
1841 ciType *inner = klass;
1842 while( inner->is_obj_array_klass() )
1843 inner = inner->as_obj_array_klass()->base_element_type();
1844 if( inner->is_instance_klass() &&
1845 !inner->as_instance_klass()->flags().is_interface() ) {
1846 // Compute index into primary_supers array
1847 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1848 // Check for overflowing; use unsigned compare to handle the negative case.
1849 if( depth < ciKlass::primary_super_limit() &&
1850 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case
1851 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1852 // (Folds up type checking code.)
1853 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1854 ciKlass *ss = klass->super_of_depth(depth);
1855 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1856 }
1857 }
1858 }
1859
1860 // If the type is enough to determine that the thing is not an array,
1861 // we can give the layout_helper a positive interval type.
1862 // This will help short-circuit some reflective code.
1863 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())
1864 && !klass->is_array_klass() // not directly typed as an array
1865 && !klass->is_interface() // specifically not Serializable & Cloneable
1866 && !klass->is_java_lang_Object() // not the supertype of all T[]
1867 ) {
1868 // Note: When interfaces are reliable, we can narrow the interface
1869 // test to (klass != Serializable && klass != Cloneable).
1870 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
1871 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
1872 // The key property of this type is that it folds up tests
1873 // for array-ness, since it proves that the layout_helper is positive.
1874 // Thus, a generic value like the basic object layout helper works fine.
1875 return TypeInt::make(min_size, max_jint, Type::WidenMin);
1876 }
1877 }
1878
1879 // If we are loading from a freshly-allocated object, produce a zero,
1880 // if the load is provably beyond the header of the object.
1881 // (Also allow a variable load from a fresh array to produce zero.)
1882 const TypeOopPtr *tinst = tp->isa_oopptr();
1883 bool is_instance = (tinst != NULL) && tinst->is_known_instance_field();
1884 bool is_boxed_value = (tinst != NULL) && tinst->is_ptr_to_boxed_value();
1885 if (ReduceFieldZeroing || is_instance || is_boxed_value) {
1886 Node* value = can_see_stored_value(mem,phase);
1887 if (value != NULL && value->is_Con()) {
1888 assert(value->bottom_type()->higher_equal(_type),"sanity");
1889 return value->bottom_type();
1890 }
1891 }
1892
1893 if (is_instance) {
1894 // If we have an instance type and our memory input is the
1895 // programs's initial memory state, there is no matching store,
1896 // so just return a zero of the appropriate type
1897 Node *mem = in(MemNode::Memory);
1898 if (mem->is_Parm() && mem->in(0)->is_Start()) {
1899 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
1900 return Type::get_zero_type(_type->basic_type());
1901 }
1902 }
1903 return _type;
1904 }
1905
1906 //------------------------------match_edge-------------------------------------
1907 // Do we Match on this edge index or not? Match only the address.
1908 uint LoadNode::match_edge(uint idx) const {
1909 return idx == MemNode::Address;
1910 }
1911
1912 //--------------------------LoadBNode::Ideal--------------------------------------
1913 //
1914 // If the previous store is to the same address as this load,
1915 // and the value stored was larger than a byte, replace this load
1916 // with the value stored truncated to a byte. If no truncation is
1917 // needed, the replacement is done in LoadNode::Identity().
1918 //
1919 Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1920 Node* mem = in(MemNode::Memory);
1921 Node* value = can_see_stored_value(mem,phase);
1922 if( value && !phase->type(value)->higher_equal( _type ) ) {
1923 Node *result = phase->transform( new LShiftINode(value, phase->intcon(24)) );
1924 return new RShiftINode(result, phase->intcon(24));
1925 }
1926 // Identity call will handle the case where truncation is not needed.
1927 return LoadNode::Ideal(phase, can_reshape);
1928 }
1929
1930 const Type* LoadBNode::Value(PhaseGVN* phase) const {
1931 Node* mem = in(MemNode::Memory);
1932 Node* value = can_see_stored_value(mem,phase);
1933 if (value != NULL && value->is_Con() &&
1934 !value->bottom_type()->higher_equal(_type)) {
1935 // If the input to the store does not fit with the load's result type,
1936 // it must be truncated. We can't delay until Ideal call since
1937 // a singleton Value is needed for split_thru_phi optimization.
1938 int con = value->get_int();
1939 return TypeInt::make((con << 24) >> 24);
1940 }
1941 return LoadNode::Value(phase);
1942 }
1943
1944 //--------------------------LoadUBNode::Ideal-------------------------------------
1945 //
1946 // If the previous store is to the same address as this load,
1947 // and the value stored was larger than a byte, replace this load
1948 // with the value stored truncated to a byte. If no truncation is
1949 // needed, the replacement is done in LoadNode::Identity().
1950 //
1951 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
1952 Node* mem = in(MemNode::Memory);
1953 Node* value = can_see_stored_value(mem, phase);
1954 if (value && !phase->type(value)->higher_equal(_type))
1955 return new AndINode(value, phase->intcon(0xFF));
1956 // Identity call will handle the case where truncation is not needed.
1957 return LoadNode::Ideal(phase, can_reshape);
1958 }
1959
1960 const Type* LoadUBNode::Value(PhaseGVN* phase) const {
1961 Node* mem = in(MemNode::Memory);
1962 Node* value = can_see_stored_value(mem,phase);
1963 if (value != NULL && value->is_Con() &&
1964 !value->bottom_type()->higher_equal(_type)) {
1965 // If the input to the store does not fit with the load's result type,
1966 // it must be truncated. We can't delay until Ideal call since
1967 // a singleton Value is needed for split_thru_phi optimization.
1968 int con = value->get_int();
1969 return TypeInt::make(con & 0xFF);
1970 }
1971 return LoadNode::Value(phase);
1972 }
1973
1974 //--------------------------LoadUSNode::Ideal-------------------------------------
1975 //
1976 // If the previous store is to the same address as this load,
1977 // and the value stored was larger than a char, replace this load
1978 // with the value stored truncated to a char. If no truncation is
1979 // needed, the replacement is done in LoadNode::Identity().
1980 //
1981 Node *LoadUSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1982 Node* mem = in(MemNode::Memory);
1983 Node* value = can_see_stored_value(mem,phase);
1984 if( value && !phase->type(value)->higher_equal( _type ) )
1985 return new AndINode(value,phase->intcon(0xFFFF));
1986 // Identity call will handle the case where truncation is not needed.
1987 return LoadNode::Ideal(phase, can_reshape);
1988 }
1989
1990 const Type* LoadUSNode::Value(PhaseGVN* phase) const {
1991 Node* mem = in(MemNode::Memory);
1992 Node* value = can_see_stored_value(mem,phase);
1993 if (value != NULL && value->is_Con() &&
1994 !value->bottom_type()->higher_equal(_type)) {
1995 // If the input to the store does not fit with the load's result type,
1996 // it must be truncated. We can't delay until Ideal call since
1997 // a singleton Value is needed for split_thru_phi optimization.
1998 int con = value->get_int();
1999 return TypeInt::make(con & 0xFFFF);
2000 }
2001 return LoadNode::Value(phase);
2002 }
2003
2004 //--------------------------LoadSNode::Ideal--------------------------------------
2005 //
2006 // If the previous store is to the same address as this load,
2007 // and the value stored was larger than a short, replace this load
2008 // with the value stored truncated to a short. If no truncation is
2009 // needed, the replacement is done in LoadNode::Identity().
2010 //
2011 Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2012 Node* mem = in(MemNode::Memory);
2013 Node* value = can_see_stored_value(mem,phase);
2014 if( value && !phase->type(value)->higher_equal( _type ) ) {
2015 Node *result = phase->transform( new LShiftINode(value, phase->intcon(16)) );
2016 return new RShiftINode(result, phase->intcon(16));
2017 }
2018 // Identity call will handle the case where truncation is not needed.
2019 return LoadNode::Ideal(phase, can_reshape);
2020 }
2021
2022 const Type* LoadSNode::Value(PhaseGVN* phase) const {
2023 Node* mem = in(MemNode::Memory);
2024 Node* value = can_see_stored_value(mem,phase);
2025 if (value != NULL && value->is_Con() &&
2026 !value->bottom_type()->higher_equal(_type)) {
2027 // If the input to the store does not fit with the load's result type,
2028 // it must be truncated. We can't delay until Ideal call since
2029 // a singleton Value is needed for split_thru_phi optimization.
2030 int con = value->get_int();
2031 return TypeInt::make((con << 16) >> 16);
2032 }
2033 return LoadNode::Value(phase);
2034 }
2035
2036 //=============================================================================
2037 //----------------------------LoadKlassNode::make------------------------------
2038 // Polymorphic factory method:
2039 Node* LoadKlassNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* at, const TypeKlassPtr* tk) {
2040 // sanity check the alias category against the created node type
2041 const TypePtr *adr_type = adr->bottom_type()->isa_ptr();
2042 assert(adr_type != NULL, "expecting TypeKlassPtr");
2043 #ifdef _LP64
2044 if (adr_type->is_ptr_to_narrowklass()) {
2045 assert(UseCompressedClassPointers, "no compressed klasses");
2046 Node* load_klass = gvn.transform(new LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowklass(), MemNode::unordered));
2047 return new DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr());
2048 }
2049 #endif
2050 assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
2051 return new LoadKlassNode(ctl, mem, adr, at, tk, MemNode::unordered);
2052 }
2053
2054 //------------------------------Value------------------------------------------
2055 const Type* LoadKlassNode::Value(PhaseGVN* phase) const {
2056 return klass_value_common(phase);
2057 }
2058
2059 // In most cases, LoadKlassNode does not have the control input set. If the control
2060 // input is set, it must not be removed (by LoadNode::Ideal()).
2061 bool LoadKlassNode::can_remove_control() const {
2062 return false;
2063 }
2064
2065 const Type* LoadNode::klass_value_common(PhaseGVN* phase) const {
2066 // Either input is TOP ==> the result is TOP
2067 const Type *t1 = phase->type( in(MemNode::Memory) );
2068 if (t1 == Type::TOP) return Type::TOP;
2069 Node *adr = in(MemNode::Address);
2070 const Type *t2 = phase->type( adr );
2071 if (t2 == Type::TOP) return Type::TOP;
2072 const TypePtr *tp = t2->is_ptr();
2073 if (TypePtr::above_centerline(tp->ptr()) ||
2074 tp->ptr() == TypePtr::Null) return Type::TOP;
2075
2076 // Return a more precise klass, if possible
2077 const TypeInstPtr *tinst = tp->isa_instptr();
2078 if (tinst != NULL) {
2079 ciInstanceKlass* ik = tinst->klass()->as_instance_klass();
2080 int offset = tinst->offset();
2081 if (ik == phase->C->env()->Class_klass()
2082 && (offset == java_lang_Class::klass_offset_in_bytes() ||
2083 offset == java_lang_Class::array_klass_offset_in_bytes())) {
2084 // We are loading a special hidden field from a Class mirror object,
2085 // the field which points to the VM's Klass metaobject.
2086 ciType* t = tinst->java_mirror_type();
2087 // java_mirror_type returns non-null for compile-time Class constants.
2088 if (t != NULL) {
2089 // constant oop => constant klass
2090 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
2091 if (t->is_void()) {
2092 // We cannot create a void array. Since void is a primitive type return null
2093 // klass. Users of this result need to do a null check on the returned klass.
2094 return TypePtr::NULL_PTR;
2095 }
2096 return TypeKlassPtr::make(ciArrayKlass::make(t));
2097 }
2098 if (!t->is_klass()) {
2099 // a primitive Class (e.g., int.class) has NULL for a klass field
2100 return TypePtr::NULL_PTR;
2101 }
2102 // (Folds up the 1st indirection in aClassConstant.getModifiers().)
2103 return TypeKlassPtr::make(t->as_klass());
2104 }
2105 // non-constant mirror, so we can't tell what's going on
2106 }
2107 if( !ik->is_loaded() )
2108 return _type; // Bail out if not loaded
2109 if (offset == oopDesc::klass_offset_in_bytes()) {
2110 if (tinst->klass_is_exact()) {
2111 return TypeKlassPtr::make(ik);
2112 }
2113 // See if we can become precise: no subklasses and no interface
2114 // (Note: We need to support verified interfaces.)
2115 if (!ik->is_interface() && !ik->has_subklass()) {
2116 //assert(!UseExactTypes, "this code should be useless with exact types");
2117 // Add a dependence; if any subclass added we need to recompile
2118 if (!ik->is_final()) {
2119 // %%% should use stronger assert_unique_concrete_subtype instead
2120 phase->C->dependencies()->assert_leaf_type(ik);
2121 }
2122 // Return precise klass
2123 return TypeKlassPtr::make(ik);
2124 }
2125
2126 // Return root of possible klass
2127 return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/);
2128 }
2129 }
2130
2131 // Check for loading klass from an array
2132 const TypeAryPtr *tary = tp->isa_aryptr();
2133 if( tary != NULL ) {
2134 ciKlass *tary_klass = tary->klass();
2135 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP
2136 && tary->offset() == oopDesc::klass_offset_in_bytes()) {
2137 if (tary->klass_is_exact()) {
2138 return TypeKlassPtr::make(tary_klass);
2139 }
2140 ciArrayKlass *ak = tary->klass()->as_array_klass();
2141 // If the klass is an object array, we defer the question to the
2142 // array component klass.
2143 if( ak->is_obj_array_klass() ) {
2144 assert( ak->is_loaded(), "" );
2145 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass();
2146 if( base_k->is_loaded() && base_k->is_instance_klass() ) {
2147 ciInstanceKlass* ik = base_k->as_instance_klass();
2148 // See if we can become precise: no subklasses and no interface
2149 if (!ik->is_interface() && !ik->has_subklass()) {
2150 //assert(!UseExactTypes, "this code should be useless with exact types");
2151 // Add a dependence; if any subclass added we need to recompile
2152 if (!ik->is_final()) {
2153 phase->C->dependencies()->assert_leaf_type(ik);
2154 }
2155 // Return precise array klass
2156 return TypeKlassPtr::make(ak);
2157 }
2158 }
2159 return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/);
2160 } else { // Found a type-array?
2161 //assert(!UseExactTypes, "this code should be useless with exact types");
2162 assert( ak->is_type_array_klass(), "" );
2163 return TypeKlassPtr::make(ak); // These are always precise
2164 }
2165 }
2166 }
2167
2168 // Check for loading klass from an array klass
2169 const TypeKlassPtr *tkls = tp->isa_klassptr();
2170 if (tkls != NULL && !StressReflectiveCode) {
2171 ciKlass* klass = tkls->klass();
2172 if( !klass->is_loaded() )
2173 return _type; // Bail out if not loaded
2174 if( klass->is_obj_array_klass() &&
2175 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) {
2176 ciKlass* elem = klass->as_obj_array_klass()->element_klass();
2177 // // Always returning precise element type is incorrect,
2178 // // e.g., element type could be object and array may contain strings
2179 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
2180
2181 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
2182 // according to the element type's subclassing.
2183 return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/);
2184 }
2185 if( klass->is_instance_klass() && tkls->klass_is_exact() &&
2186 tkls->offset() == in_bytes(Klass::super_offset())) {
2187 ciKlass* sup = klass->as_instance_klass()->super();
2188 // The field is Klass::_super. Return its (constant) value.
2189 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
2190 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR;
2191 }
2192 }
2193
2194 // Bailout case
2195 return LoadNode::Value(phase);
2196 }
2197
2198 //------------------------------Identity---------------------------------------
2199 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
2200 // Also feed through the klass in Allocate(...klass...)._klass.
2201 Node* LoadKlassNode::Identity(PhaseGVN* phase) {
2202 return klass_identity_common(phase);
2203 }
2204
2205 Node* LoadNode::klass_identity_common(PhaseGVN* phase) {
2206 Node* x = LoadNode::Identity(phase);
2207 if (x != this) return x;
2208
2209 // Take apart the address into an oop and and offset.
2210 // Return 'this' if we cannot.
2211 Node* adr = in(MemNode::Address);
2212 intptr_t offset = 0;
2213 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2214 if (base == NULL) return this;
2215 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
2216 if (toop == NULL) return this;
2217
2218 // Step over potential GC barrier for OopHandle resolve
2219 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
2220 if (bs->is_gc_barrier_node(base)) {
2221 base = bs->step_over_gc_barrier(base);
2222 }
2223
2224 // We can fetch the klass directly through an AllocateNode.
2225 // This works even if the klass is not constant (clone or newArray).
2226 if (offset == oopDesc::klass_offset_in_bytes()) {
2227 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
2228 if (allocated_klass != NULL) {
2229 return allocated_klass;
2230 }
2231 }
2232
2233 // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*.
2234 // See inline_native_Class_query for occurrences of these patterns.
2235 // Java Example: x.getClass().isAssignableFrom(y)
2236 //
2237 // This improves reflective code, often making the Class
2238 // mirror go completely dead. (Current exception: Class
2239 // mirrors may appear in debug info, but we could clean them out by
2240 // introducing a new debug info operator for Klass.java_mirror).
2241
2242 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass()
2243 && offset == java_lang_Class::klass_offset_in_bytes()) {
2244 if (base->is_Load()) {
2245 Node* base2 = base->in(MemNode::Address);
2246 if (base2->is_Load()) { /* direct load of a load which is the OopHandle */
2247 Node* adr2 = base2->in(MemNode::Address);
2248 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2249 if (tkls != NULL && !tkls->empty()
2250 && (tkls->klass()->is_instance_klass() ||
2251 tkls->klass()->is_array_klass())
2252 && adr2->is_AddP()
2253 ) {
2254 int mirror_field = in_bytes(Klass::java_mirror_offset());
2255 if (tkls->offset() == mirror_field) {
2256 return adr2->in(AddPNode::Base);
2257 }
2258 }
2259 }
2260 }
2261 }
2262
2263 return this;
2264 }
2265
2266
2267 //------------------------------Value------------------------------------------
2268 const Type* LoadNKlassNode::Value(PhaseGVN* phase) const {
2269 const Type *t = klass_value_common(phase);
2270 if (t == Type::TOP)
2271 return t;
2272
2273 return t->make_narrowklass();
2274 }
2275
2276 //------------------------------Identity---------------------------------------
2277 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
2278 // Also feed through the klass in Allocate(...klass...)._klass.
2279 Node* LoadNKlassNode::Identity(PhaseGVN* phase) {
2280 Node *x = klass_identity_common(phase);
2281
2282 const Type *t = phase->type( x );
2283 if( t == Type::TOP ) return x;
2284 if( t->isa_narrowklass()) return x;
2285 assert (!t->isa_narrowoop(), "no narrow oop here");
2286
2287 return phase->transform(new EncodePKlassNode(x, t->make_narrowklass()));
2288 }
2289
2290 //------------------------------Value-----------------------------------------
2291 const Type* LoadRangeNode::Value(PhaseGVN* phase) const {
2292 // Either input is TOP ==> the result is TOP
2293 const Type *t1 = phase->type( in(MemNode::Memory) );
2294 if( t1 == Type::TOP ) return Type::TOP;
2295 Node *adr = in(MemNode::Address);
2296 const Type *t2 = phase->type( adr );
2297 if( t2 == Type::TOP ) return Type::TOP;
2298 const TypePtr *tp = t2->is_ptr();
2299 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
2300 const TypeAryPtr *tap = tp->isa_aryptr();
2301 if( !tap ) return _type;
2302 return tap->size();
2303 }
2304
2305 //-------------------------------Ideal---------------------------------------
2306 // Feed through the length in AllocateArray(...length...)._length.
2307 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2308 Node* p = MemNode::Ideal_common(phase, can_reshape);
2309 if (p) return (p == NodeSentinel) ? NULL : p;
2310
2311 // Take apart the address into an oop and and offset.
2312 // Return 'this' if we cannot.
2313 Node* adr = in(MemNode::Address);
2314 intptr_t offset = 0;
2315 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2316 if (base == NULL) return NULL;
2317 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2318 if (tary == NULL) return NULL;
2319
2320 // We can fetch the length directly through an AllocateArrayNode.
2321 // This works even if the length is not constant (clone or newArray).
2322 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2323 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2324 if (alloc != NULL) {
2325 Node* allocated_length = alloc->Ideal_length();
2326 Node* len = alloc->make_ideal_length(tary, phase);
2327 if (allocated_length != len) {
2328 // New CastII improves on this.
2329 return len;
2330 }
2331 }
2332 }
2333
2334 return NULL;
2335 }
2336
2337 //------------------------------Identity---------------------------------------
2338 // Feed through the length in AllocateArray(...length...)._length.
2339 Node* LoadRangeNode::Identity(PhaseGVN* phase) {
2340 Node* x = LoadINode::Identity(phase);
2341 if (x != this) return x;
2342
2343 // Take apart the address into an oop and and offset.
2344 // Return 'this' if we cannot.
2345 Node* adr = in(MemNode::Address);
2346 intptr_t offset = 0;
2347 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2348 if (base == NULL) return this;
2349 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2350 if (tary == NULL) return this;
2351
2352 // We can fetch the length directly through an AllocateArrayNode.
2353 // This works even if the length is not constant (clone or newArray).
2354 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2355 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2356 if (alloc != NULL) {
2357 Node* allocated_length = alloc->Ideal_length();
2358 // Do not allow make_ideal_length to allocate a CastII node.
2359 Node* len = alloc->make_ideal_length(tary, phase, false);
2360 if (allocated_length == len) {
2361 // Return allocated_length only if it would not be improved by a CastII.
2362 return allocated_length;
2363 }
2364 }
2365 }
2366
2367 return this;
2368
2369 }
2370
2371 //=============================================================================
2372 //---------------------------StoreNode::make-----------------------------------
2373 // Polymorphic factory method:
2374 StoreNode* StoreNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt, MemOrd mo) {
2375 assert((mo == unordered || mo == release), "unexpected");
2376 Compile* C = gvn.C;
2377 assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2378 ctl != NULL, "raw memory operations should have control edge");
2379
2380 switch (bt) {
2381 case T_BOOLEAN: val = gvn.transform(new AndINode(val, gvn.intcon(0x1))); // Fall through to T_BYTE case
2382 case T_BYTE: return new StoreBNode(ctl, mem, adr, adr_type, val, mo);
2383 case T_INT: return new StoreINode(ctl, mem, adr, adr_type, val, mo);
2384 case T_CHAR:
2385 case T_SHORT: return new StoreCNode(ctl, mem, adr, adr_type, val, mo);
2386 case T_LONG: return new StoreLNode(ctl, mem, adr, adr_type, val, mo);
2387 case T_FLOAT: return new StoreFNode(ctl, mem, adr, adr_type, val, mo);
2388 case T_DOUBLE: return new StoreDNode(ctl, mem, adr, adr_type, val, mo);
2389 case T_METADATA:
2390 case T_ADDRESS:
2391 case T_OBJECT:
2392 #ifdef _LP64
2393 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
2394 val = gvn.transform(new EncodePNode(val, val->bottom_type()->make_narrowoop()));
2395 return new StoreNNode(ctl, mem, adr, adr_type, val, mo);
2396 } else if (adr->bottom_type()->is_ptr_to_narrowklass() ||
2397 (UseCompressedClassPointers && val->bottom_type()->isa_klassptr() &&
2398 adr->bottom_type()->isa_rawptr())) {
2399 val = gvn.transform(new EncodePKlassNode(val, val->bottom_type()->make_narrowklass()));
2400 return new StoreNKlassNode(ctl, mem, adr, adr_type, val, mo);
2401 }
2402 #endif
2403 {
2404 return new StorePNode(ctl, mem, adr, adr_type, val, mo);
2405 }
2406 default:
2407 ShouldNotReachHere();
2408 return (StoreNode*)NULL;
2409 }
2410 }
2411
2412 StoreLNode* StoreLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
2413 bool require_atomic = true;
2414 return new StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
2415 }
2416
2417 StoreDNode* StoreDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
2418 bool require_atomic = true;
2419 return new StoreDNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
2420 }
2421
2422
2423 //--------------------------bottom_type----------------------------------------
2424 const Type *StoreNode::bottom_type() const {
2425 return Type::MEMORY;
2426 }
2427
2428 //------------------------------hash-------------------------------------------
2429 uint StoreNode::hash() const {
2430 // unroll addition of interesting fields
2431 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2432
2433 // Since they are not commoned, do not hash them:
2434 return NO_HASH;
2435 }
2436
2437 //------------------------------Ideal------------------------------------------
2438 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
2439 // When a store immediately follows a relevant allocation/initialization,
2440 // try to capture it into the initialization, or hoist it above.
2441 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2442 Node* p = MemNode::Ideal_common(phase, can_reshape);
2443 if (p) return (p == NodeSentinel) ? NULL : p;
2444
2445 Node* mem = in(MemNode::Memory);
2446 Node* address = in(MemNode::Address);
2447 // Back-to-back stores to same address? Fold em up. Generally
2448 // unsafe if I have intervening uses... Also disallowed for StoreCM
2449 // since they must follow each StoreP operation. Redundant StoreCMs
2450 // are eliminated just before matching in final_graph_reshape.
2451 {
2452 Node* st = mem;
2453 // If Store 'st' has more than one use, we cannot fold 'st' away.
2454 // For example, 'st' might be the final state at a conditional
2455 // return. Or, 'st' might be used by some node which is live at
2456 // the same time 'st' is live, which might be unschedulable. So,
2457 // require exactly ONE user until such time as we clone 'mem' for
2458 // each of 'mem's uses (thus making the exactly-1-user-rule hold
2459 // true).
2460 while (st->is_Store() && st->outcnt() == 1 && st->Opcode() != Op_StoreCM) {
2461 // Looking at a dead closed cycle of memory?
2462 assert(st != st->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
2463 assert(Opcode() == st->Opcode() ||
2464 st->Opcode() == Op_StoreVector ||
2465 Opcode() == Op_StoreVector ||
2466 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw ||
2467 (Opcode() == Op_StoreL && st->Opcode() == Op_StoreI) || // expanded ClearArrayNode
2468 (Opcode() == Op_StoreI && st->Opcode() == Op_StoreL) || // initialization by arraycopy
2469 (is_mismatched_access() || st->as_Store()->is_mismatched_access()),
2470 "no mismatched stores, except on raw memory: %s %s", NodeClassNames[Opcode()], NodeClassNames[st->Opcode()]);
2471
2472 if (st->in(MemNode::Address)->eqv_uncast(address) &&
2473 st->as_Store()->memory_size() <= this->memory_size()) {
2474 Node* use = st->raw_out(0);
2475 phase->igvn_rehash_node_delayed(use);
2476 if (can_reshape) {
2477 use->set_req_X(MemNode::Memory, st->in(MemNode::Memory), phase->is_IterGVN());
2478 } else {
2479 // It's OK to do this in the parser, since DU info is always accurate,
2480 // and the parser always refers to nodes via SafePointNode maps.
2481 use->set_req(MemNode::Memory, st->in(MemNode::Memory));
2482 }
2483 return this;
2484 }
2485 st = st->in(MemNode::Memory);
2486 }
2487 }
2488
2489
2490 // Capture an unaliased, unconditional, simple store into an initializer.
2491 // Or, if it is independent of the allocation, hoist it above the allocation.
2492 if (ReduceFieldZeroing && /*can_reshape &&*/
2493 mem->is_Proj() && mem->in(0)->is_Initialize()) {
2494 InitializeNode* init = mem->in(0)->as_Initialize();
2495 intptr_t offset = init->can_capture_store(this, phase, can_reshape);
2496 if (offset > 0) {
2497 Node* moved = init->capture_store(this, offset, phase, can_reshape);
2498 // If the InitializeNode captured me, it made a raw copy of me,
2499 // and I need to disappear.
2500 if (moved != NULL) {
2501 // %%% hack to ensure that Ideal returns a new node:
2502 mem = MergeMemNode::make(mem);
2503 return mem; // fold me away
2504 }
2505 }
2506 }
2507
2508 return NULL; // No further progress
2509 }
2510
2511 //------------------------------Value-----------------------------------------
2512 const Type* StoreNode::Value(PhaseGVN* phase) const {
2513 // Either input is TOP ==> the result is TOP
2514 const Type *t1 = phase->type( in(MemNode::Memory) );
2515 if( t1 == Type::TOP ) return Type::TOP;
2516 const Type *t2 = phase->type( in(MemNode::Address) );
2517 if( t2 == Type::TOP ) return Type::TOP;
2518 const Type *t3 = phase->type( in(MemNode::ValueIn) );
2519 if( t3 == Type::TOP ) return Type::TOP;
2520 return Type::MEMORY;
2521 }
2522
2523 //------------------------------Identity---------------------------------------
2524 // Remove redundant stores:
2525 // Store(m, p, Load(m, p)) changes to m.
2526 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
2527 Node* StoreNode::Identity(PhaseGVN* phase) {
2528 Node* mem = in(MemNode::Memory);
2529 Node* adr = in(MemNode::Address);
2530 Node* val = in(MemNode::ValueIn);
2531
2532 Node* result = this;
2533
2534 // Load then Store? Then the Store is useless
2535 if (val->is_Load() &&
2536 val->in(MemNode::Address)->eqv_uncast(adr) &&
2537 val->in(MemNode::Memory )->eqv_uncast(mem) &&
2538 val->as_Load()->store_Opcode() == Opcode()) {
2539 result = mem;
2540 }
2541
2542 // Two stores in a row of the same value?
2543 if (result == this &&
2544 mem->is_Store() &&
2545 mem->in(MemNode::Address)->eqv_uncast(adr) &&
2546 mem->in(MemNode::ValueIn)->eqv_uncast(val) &&
2547 mem->Opcode() == Opcode()) {
2548 result = mem;
2549 }
2550
2551 // Store of zero anywhere into a freshly-allocated object?
2552 // Then the store is useless.
2553 // (It must already have been captured by the InitializeNode.)
2554 if (result == this &&
2555 ReduceFieldZeroing && phase->type(val)->is_zero_type()) {
2556 // a newly allocated object is already all-zeroes everywhere
2557 if (mem->is_Proj() && mem->in(0)->is_Allocate()) {
2558 result = mem;
2559 }
2560
2561 if (result == this) {
2562 // the store may also apply to zero-bits in an earlier object
2563 Node* prev_mem = find_previous_store(phase);
2564 // Steps (a), (b): Walk past independent stores to find an exact match.
2565 if (prev_mem != NULL) {
2566 Node* prev_val = can_see_stored_value(prev_mem, phase);
2567 if (prev_val != NULL && phase->eqv(prev_val, val)) {
2568 // prev_val and val might differ by a cast; it would be good
2569 // to keep the more informative of the two.
2570 result = mem;
2571 }
2572 }
2573 }
2574 }
2575
2576 if (result != this && phase->is_IterGVN() != NULL) {
2577 MemBarNode* trailing = trailing_membar();
2578 if (trailing != NULL) {
2579 #ifdef ASSERT
2580 const TypeOopPtr* t_oop = phase->type(in(Address))->isa_oopptr();
2581 assert(t_oop == NULL || t_oop->is_known_instance_field(), "only for non escaping objects");
2582 #endif
2583 PhaseIterGVN* igvn = phase->is_IterGVN();
2584 trailing->remove(igvn);
2585 }
2586 }
2587
2588 return result;
2589 }
2590
2591 //------------------------------match_edge-------------------------------------
2592 // Do we Match on this edge index or not? Match only memory & value
2593 uint StoreNode::match_edge(uint idx) const {
2594 return idx == MemNode::Address || idx == MemNode::ValueIn;
2595 }
2596
2597 //------------------------------cmp--------------------------------------------
2598 // Do not common stores up together. They generally have to be split
2599 // back up anyways, so do not bother.
2600 uint StoreNode::cmp( const Node &n ) const {
2601 return (&n == this); // Always fail except on self
2602 }
2603
2604 //------------------------------Ideal_masked_input-----------------------------
2605 // Check for a useless mask before a partial-word store
2606 // (StoreB ... (AndI valIn conIa) )
2607 // If (conIa & mask == mask) this simplifies to
2608 // (StoreB ... (valIn) )
2609 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
2610 Node *val = in(MemNode::ValueIn);
2611 if( val->Opcode() == Op_AndI ) {
2612 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2613 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
2614 set_req(MemNode::ValueIn, val->in(1));
2615 return this;
2616 }
2617 }
2618 return NULL;
2619 }
2620
2621
2622 //------------------------------Ideal_sign_extended_input----------------------
2623 // Check for useless sign-extension before a partial-word store
2624 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) )
2625 // If (conIL == conIR && conIR <= num_bits) this simplifies to
2626 // (StoreB ... (valIn) )
2627 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) {
2628 Node *val = in(MemNode::ValueIn);
2629 if( val->Opcode() == Op_RShiftI ) {
2630 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2631 if( t && t->is_con() && (t->get_con() <= num_bits) ) {
2632 Node *shl = val->in(1);
2633 if( shl->Opcode() == Op_LShiftI ) {
2634 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int();
2635 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) {
2636 set_req(MemNode::ValueIn, shl->in(1));
2637 return this;
2638 }
2639 }
2640 }
2641 }
2642 return NULL;
2643 }
2644
2645 //------------------------------value_never_loaded-----------------------------------
2646 // Determine whether there are any possible loads of the value stored.
2647 // For simplicity, we actually check if there are any loads from the
2648 // address stored to, not just for loads of the value stored by this node.
2649 //
2650 bool StoreNode::value_never_loaded( PhaseTransform *phase) const {
2651 Node *adr = in(Address);
2652 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
2653 if (adr_oop == NULL)
2654 return false;
2655 if (!adr_oop->is_known_instance_field())
2656 return false; // if not a distinct instance, there may be aliases of the address
2657 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
2658 Node *use = adr->fast_out(i);
2659 if (use->is_Load() || use->is_LoadStore()) {
2660 return false;
2661 }
2662 }
2663 return true;
2664 }
2665
2666 MemBarNode* StoreNode::trailing_membar() const {
2667 if (is_release()) {
2668 MemBarNode* trailing_mb = NULL;
2669 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
2670 Node* u = fast_out(i);
2671 if (u->is_MemBar()) {
2672 if (u->as_MemBar()->trailing_store()) {
2673 assert(u->Opcode() == Op_MemBarVolatile, "");
2674 assert(trailing_mb == NULL, "only one");
2675 trailing_mb = u->as_MemBar();
2676 #ifdef ASSERT
2677 Node* leading = u->as_MemBar()->leading_membar();
2678 assert(leading->Opcode() == Op_MemBarRelease, "incorrect membar");
2679 assert(leading->as_MemBar()->leading_store(), "incorrect membar pair");
2680 assert(leading->as_MemBar()->trailing_membar() == u, "incorrect membar pair");
2681 #endif
2682 } else {
2683 assert(u->as_MemBar()->standalone(), "");
2684 }
2685 }
2686 }
2687 return trailing_mb;
2688 }
2689 return NULL;
2690 }
2691
2692
2693 //=============================================================================
2694 //------------------------------Ideal------------------------------------------
2695 // If the store is from an AND mask that leaves the low bits untouched, then
2696 // we can skip the AND operation. If the store is from a sign-extension
2697 // (a left shift, then right shift) we can skip both.
2698 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
2699 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
2700 if( progress != NULL ) return progress;
2701
2702 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
2703 if( progress != NULL ) return progress;
2704
2705 // Finally check the default case
2706 return StoreNode::Ideal(phase, can_reshape);
2707 }
2708
2709 //=============================================================================
2710 //------------------------------Ideal------------------------------------------
2711 // If the store is from an AND mask that leaves the low bits untouched, then
2712 // we can skip the AND operation
2713 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
2714 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
2715 if( progress != NULL ) return progress;
2716
2717 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
2718 if( progress != NULL ) return progress;
2719
2720 // Finally check the default case
2721 return StoreNode::Ideal(phase, can_reshape);
2722 }
2723
2724 //=============================================================================
2725 //------------------------------Identity---------------------------------------
2726 Node* StoreCMNode::Identity(PhaseGVN* phase) {
2727 // No need to card mark when storing a null ptr
2728 Node* my_store = in(MemNode::OopStore);
2729 if (my_store->is_Store()) {
2730 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) );
2731 if( t1 == TypePtr::NULL_PTR ) {
2732 return in(MemNode::Memory);
2733 }
2734 }
2735 return this;
2736 }
2737
2738 //=============================================================================
2739 //------------------------------Ideal---------------------------------------
2740 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){
2741 Node* progress = StoreNode::Ideal(phase, can_reshape);
2742 if (progress != NULL) return progress;
2743
2744 Node* my_store = in(MemNode::OopStore);
2745 if (my_store->is_MergeMem()) {
2746 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx());
2747 set_req(MemNode::OopStore, mem);
2748 return this;
2749 }
2750
2751 return NULL;
2752 }
2753
2754 //------------------------------Value-----------------------------------------
2755 const Type* StoreCMNode::Value(PhaseGVN* phase) const {
2756 // Either input is TOP ==> the result is TOP
2757 const Type *t = phase->type( in(MemNode::Memory) );
2758 if( t == Type::TOP ) return Type::TOP;
2759 t = phase->type( in(MemNode::Address) );
2760 if( t == Type::TOP ) return Type::TOP;
2761 t = phase->type( in(MemNode::ValueIn) );
2762 if( t == Type::TOP ) return Type::TOP;
2763 // If extra input is TOP ==> the result is TOP
2764 t = phase->type( in(MemNode::OopStore) );
2765 if( t == Type::TOP ) return Type::TOP;
2766
2767 return StoreNode::Value( phase );
2768 }
2769
2770
2771 //=============================================================================
2772 //----------------------------------SCMemProjNode------------------------------
2773 const Type* SCMemProjNode::Value(PhaseGVN* phase) const
2774 {
2775 return bottom_type();
2776 }
2777
2778 //=============================================================================
2779 //----------------------------------LoadStoreNode------------------------------
2780 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required )
2781 : Node(required),
2782 _type(rt),
2783 _adr_type(at)
2784 {
2785 init_req(MemNode::Control, c );
2786 init_req(MemNode::Memory , mem);
2787 init_req(MemNode::Address, adr);
2788 init_req(MemNode::ValueIn, val);
2789 init_class_id(Class_LoadStore);
2790 }
2791
2792 uint LoadStoreNode::ideal_reg() const {
2793 return _type->ideal_reg();
2794 }
2795
2796 bool LoadStoreNode::result_not_used() const {
2797 for( DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++ ) {
2798 Node *x = fast_out(i);
2799 if (x->Opcode() == Op_SCMemProj) continue;
2800 return false;
2801 }
2802 return true;
2803 }
2804
2805 MemBarNode* LoadStoreNode::trailing_membar() const {
2806 MemBarNode* trailing = NULL;
2807 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
2808 Node* u = fast_out(i);
2809 if (u->is_MemBar()) {
2810 if (u->as_MemBar()->trailing_load_store()) {
2811 assert(u->Opcode() == Op_MemBarAcquire, "");
2812 assert(trailing == NULL, "only one");
2813 trailing = u->as_MemBar();
2814 #ifdef ASSERT
2815 Node* leading = trailing->leading_membar();
2816 assert(support_IRIW_for_not_multiple_copy_atomic_cpu || leading->Opcode() == Op_MemBarRelease, "incorrect membar");
2817 assert(leading->as_MemBar()->leading_load_store(), "incorrect membar pair");
2818 assert(leading->as_MemBar()->trailing_membar() == trailing, "incorrect membar pair");
2819 #endif
2820 } else {
2821 assert(u->as_MemBar()->standalone(), "wrong barrier kind");
2822 }
2823 }
2824 }
2825
2826 return trailing;
2827 }
2828
2829 uint LoadStoreNode::size_of() const { return sizeof(*this); }
2830
2831 //=============================================================================
2832 //----------------------------------LoadStoreConditionalNode--------------------
2833 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, NULL, TypeInt::BOOL, 5) {
2834 init_req(ExpectedIn, ex );
2835 }
2836
2837 //=============================================================================
2838 //-------------------------------adr_type--------------------------------------
2839 const TypePtr* ClearArrayNode::adr_type() const {
2840 Node *adr = in(3);
2841 if (adr == NULL) return NULL; // node is dead
2842 return MemNode::calculate_adr_type(adr->bottom_type());
2843 }
2844
2845 //------------------------------match_edge-------------------------------------
2846 // Do we Match on this edge index or not? Do not match memory
2847 uint ClearArrayNode::match_edge(uint idx) const {
2848 return idx > 1;
2849 }
2850
2851 //------------------------------Identity---------------------------------------
2852 // Clearing a zero length array does nothing
2853 Node* ClearArrayNode::Identity(PhaseGVN* phase) {
2854 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
2855 }
2856
2857 //------------------------------Idealize---------------------------------------
2858 // Clearing a short array is faster with stores
2859 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2860 // Already know this is a large node, do not try to ideal it
2861 if (!IdealizeClearArrayNode || _is_large) return NULL;
2862
2863 const int unit = BytesPerLong;
2864 const TypeX* t = phase->type(in(2))->isa_intptr_t();
2865 if (!t) return NULL;
2866 if (!t->is_con()) return NULL;
2867 intptr_t raw_count = t->get_con();
2868 intptr_t size = raw_count;
2869 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
2870 // Clearing nothing uses the Identity call.
2871 // Negative clears are possible on dead ClearArrays
2872 // (see jck test stmt114.stmt11402.val).
2873 if (size <= 0 || size % unit != 0) return NULL;
2874 intptr_t count = size / unit;
2875 // Length too long; communicate this to matchers and assemblers.
2876 // Assemblers are responsible to produce fast hardware clears for it.
2877 if (size > InitArrayShortSize) {
2878 return new ClearArrayNode(in(0), in(1), in(2), in(3), true);
2879 }
2880 Node *mem = in(1);
2881 if( phase->type(mem)==Type::TOP ) return NULL;
2882 Node *adr = in(3);
2883 const Type* at = phase->type(adr);
2884 if( at==Type::TOP ) return NULL;
2885 const TypePtr* atp = at->isa_ptr();
2886 // adjust atp to be the correct array element address type
2887 if (atp == NULL) atp = TypePtr::BOTTOM;
2888 else atp = atp->add_offset(Type::OffsetBot);
2889 // Get base for derived pointer purposes
2890 if( adr->Opcode() != Op_AddP ) Unimplemented();
2891 Node *base = adr->in(1);
2892
2893 Node *zero = phase->makecon(TypeLong::ZERO);
2894 Node *off = phase->MakeConX(BytesPerLong);
2895 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
2896 count--;
2897 while( count-- ) {
2898 mem = phase->transform(mem);
2899 adr = phase->transform(new AddPNode(base,adr,off));
2900 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
2901 }
2902 return mem;
2903 }
2904
2905 //----------------------------step_through----------------------------------
2906 // Return allocation input memory edge if it is different instance
2907 // or itself if it is the one we are looking for.
2908 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) {
2909 Node* n = *np;
2910 assert(n->is_ClearArray(), "sanity");
2911 intptr_t offset;
2912 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
2913 // This method is called only before Allocate nodes are expanded
2914 // during macro nodes expansion. Before that ClearArray nodes are
2915 // only generated in PhaseMacroExpand::generate_arraycopy() (before
2916 // Allocate nodes are expanded) which follows allocations.
2917 assert(alloc != NULL, "should have allocation");
2918 if (alloc->_idx == instance_id) {
2919 // Can not bypass initialization of the instance we are looking for.
2920 return false;
2921 }
2922 // Otherwise skip it.
2923 InitializeNode* init = alloc->initialization();
2924 if (init != NULL)
2925 *np = init->in(TypeFunc::Memory);
2926 else
2927 *np = alloc->in(TypeFunc::Memory);
2928 return true;
2929 }
2930
2931 //----------------------------clear_memory-------------------------------------
2932 // Generate code to initialize object storage to zero.
2933 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2934 intptr_t start_offset,
2935 Node* end_offset,
2936 PhaseGVN* phase) {
2937 intptr_t offset = start_offset;
2938
2939 int unit = BytesPerLong;
2940 if ((offset % unit) != 0) {
2941 Node* adr = new AddPNode(dest, dest, phase->MakeConX(offset));
2942 adr = phase->transform(adr);
2943 const TypePtr* atp = TypeRawPtr::BOTTOM;
2944 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
2945 mem = phase->transform(mem);
2946 offset += BytesPerInt;
2947 }
2948 assert((offset % unit) == 0, "");
2949
2950 // Initialize the remaining stuff, if any, with a ClearArray.
2951 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase);
2952 }
2953
2954 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2955 Node* start_offset,
2956 Node* end_offset,
2957 PhaseGVN* phase) {
2958 if (start_offset == end_offset) {
2959 // nothing to do
2960 return mem;
2961 }
2962
2963 int unit = BytesPerLong;
2964 Node* zbase = start_offset;
2965 Node* zend = end_offset;
2966
2967 // Scale to the unit required by the CPU:
2968 if (!Matcher::init_array_count_is_in_bytes) {
2969 Node* shift = phase->intcon(exact_log2(unit));
2970 zbase = phase->transform(new URShiftXNode(zbase, shift) );
2971 zend = phase->transform(new URShiftXNode(zend, shift) );
2972 }
2973
2974 // Bulk clear double-words
2975 Node* zsize = phase->transform(new SubXNode(zend, zbase) );
2976 Node* adr = phase->transform(new AddPNode(dest, dest, start_offset) );
2977 mem = new ClearArrayNode(ctl, mem, zsize, adr, false);
2978 return phase->transform(mem);
2979 }
2980
2981 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2982 intptr_t start_offset,
2983 intptr_t end_offset,
2984 PhaseGVN* phase) {
2985 if (start_offset == end_offset) {
2986 // nothing to do
2987 return mem;
2988 }
2989
2990 assert((end_offset % BytesPerInt) == 0, "odd end offset");
2991 intptr_t done_offset = end_offset;
2992 if ((done_offset % BytesPerLong) != 0) {
2993 done_offset -= BytesPerInt;
2994 }
2995 if (done_offset > start_offset) {
2996 mem = clear_memory(ctl, mem, dest,
2997 start_offset, phase->MakeConX(done_offset), phase);
2998 }
2999 if (done_offset < end_offset) { // emit the final 32-bit store
3000 Node* adr = new AddPNode(dest, dest, phase->MakeConX(done_offset));
3001 adr = phase->transform(adr);
3002 const TypePtr* atp = TypeRawPtr::BOTTOM;
3003 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
3004 mem = phase->transform(mem);
3005 done_offset += BytesPerInt;
3006 }
3007 assert(done_offset == end_offset, "");
3008 return mem;
3009 }
3010
3011 //=============================================================================
3012 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
3013 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)),
3014 _adr_type(C->get_adr_type(alias_idx)), _kind(Standalone)
3015 #ifdef ASSERT
3016 , _pair_idx(0)
3017 #endif
3018 {
3019 init_class_id(Class_MemBar);
3020 Node* top = C->top();
3021 init_req(TypeFunc::I_O,top);
3022 init_req(TypeFunc::FramePtr,top);
3023 init_req(TypeFunc::ReturnAdr,top);
3024 if (precedent != NULL)
3025 init_req(TypeFunc::Parms, precedent);
3026 }
3027
3028 //------------------------------cmp--------------------------------------------
3029 uint MemBarNode::hash() const { return NO_HASH; }
3030 uint MemBarNode::cmp( const Node &n ) const {
3031 return (&n == this); // Always fail except on self
3032 }
3033
3034 //------------------------------make-------------------------------------------
3035 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
3036 switch (opcode) {
3037 case Op_MemBarAcquire: return new MemBarAcquireNode(C, atp, pn);
3038 case Op_LoadFence: return new LoadFenceNode(C, atp, pn);
3039 case Op_MemBarRelease: return new MemBarReleaseNode(C, atp, pn);
3040 case Op_StoreFence: return new StoreFenceNode(C, atp, pn);
3041 case Op_MemBarAcquireLock: return new MemBarAcquireLockNode(C, atp, pn);
3042 case Op_MemBarReleaseLock: return new MemBarReleaseLockNode(C, atp, pn);
3043 case Op_MemBarVolatile: return new MemBarVolatileNode(C, atp, pn);
3044 case Op_MemBarCPUOrder: return new MemBarCPUOrderNode(C, atp, pn);
3045 case Op_OnSpinWait: return new OnSpinWaitNode(C, atp, pn);
3046 case Op_Initialize: return new InitializeNode(C, atp, pn);
3047 case Op_MemBarStoreStore: return new MemBarStoreStoreNode(C, atp, pn);
3048 default: ShouldNotReachHere(); return NULL;
3049 }
3050 }
3051
3052 void MemBarNode::remove(PhaseIterGVN *igvn) {
3053 if (outcnt() != 2) {
3054 return;
3055 }
3056 if (trailing_store() || trailing_load_store()) {
3057 MemBarNode* leading = leading_membar();
3058 if (leading != NULL) {
3059 assert(leading->trailing_membar() == this, "inconsistent leading/trailing membars");
3060 leading->remove(igvn);
3061 }
3062 }
3063 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
3064 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
3065 }
3066
3067 //------------------------------Ideal------------------------------------------
3068 // Return a node which is more "ideal" than the current node. Strip out
3069 // control copies
3070 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3071 if (remove_dead_region(phase, can_reshape)) return this;
3072 // Don't bother trying to transform a dead node
3073 if (in(0) && in(0)->is_top()) {
3074 return NULL;
3075 }
3076
3077 #if INCLUDE_ZGC
3078 if (UseZGC) {
3079 if (req() == (Precedent+1) && in(MemBarNode::Precedent)->in(0) != NULL && in(MemBarNode::Precedent)->in(0)->is_LoadBarrier()) {
3080 Node* load_node = in(MemBarNode::Precedent)->in(0)->in(LoadBarrierNode::Oop);
3081 set_req(MemBarNode::Precedent, load_node);
3082 return this;
3083 }
3084 }
3085 #endif
3086
3087 bool progress = false;
3088 // Eliminate volatile MemBars for scalar replaced objects.
3089 if (can_reshape && req() == (Precedent+1)) {
3090 bool eliminate = false;
3091 int opc = Opcode();
3092 if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) {
3093 // Volatile field loads and stores.
3094 Node* my_mem = in(MemBarNode::Precedent);
3095 // The MembarAquire may keep an unused LoadNode alive through the Precedent edge
3096 if ((my_mem != NULL) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) {
3097 // if the Precedent is a decodeN and its input (a Load) is used at more than one place,
3098 // replace this Precedent (decodeN) with the Load instead.
3099 if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1)) {
3100 Node* load_node = my_mem->in(1);
3101 set_req(MemBarNode::Precedent, load_node);
3102 phase->is_IterGVN()->_worklist.push(my_mem);
3103 my_mem = load_node;
3104 } else {
3105 assert(my_mem->unique_out() == this, "sanity");
3106 del_req(Precedent);
3107 phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later
3108 my_mem = NULL;
3109 }
3110 progress = true;
3111 }
3112 if (my_mem != NULL && my_mem->is_Mem()) {
3113 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
3114 // Check for scalar replaced object reference.
3115 if( t_oop != NULL && t_oop->is_known_instance_field() &&
3116 t_oop->offset() != Type::OffsetBot &&
3117 t_oop->offset() != Type::OffsetTop) {
3118 eliminate = true;
3119 }
3120 }
3121 } else if (opc == Op_MemBarRelease) {
3122 // Final field stores.
3123 Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent), phase);
3124 if ((alloc != NULL) && alloc->is_Allocate() &&
3125 alloc->as_Allocate()->does_not_escape_thread()) {
3126 // The allocated object does not escape.
3127 eliminate = true;
3128 }
3129 }
3130 if (eliminate) {
3131 // Replace MemBar projections by its inputs.
3132 PhaseIterGVN* igvn = phase->is_IterGVN();
3133 remove(igvn);
3134 // Must return either the original node (now dead) or a new node
3135 // (Do not return a top here, since that would break the uniqueness of top.)
3136 return new ConINode(TypeInt::ZERO);
3137 }
3138 }
3139 return progress ? this : NULL;
3140 }
3141
3142 //------------------------------Value------------------------------------------
3143 const Type* MemBarNode::Value(PhaseGVN* phase) const {
3144 if( !in(0) ) return Type::TOP;
3145 if( phase->type(in(0)) == Type::TOP )
3146 return Type::TOP;
3147 return TypeTuple::MEMBAR;
3148 }
3149
3150 //------------------------------match------------------------------------------
3151 // Construct projections for memory.
3152 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) {
3153 switch (proj->_con) {
3154 case TypeFunc::Control:
3155 case TypeFunc::Memory:
3156 return new MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
3157 }
3158 ShouldNotReachHere();
3159 return NULL;
3160 }
3161
3162 void MemBarNode::set_store_pair(MemBarNode* leading, MemBarNode* trailing) {
3163 trailing->_kind = TrailingStore;
3164 leading->_kind = LeadingStore;
3165 #ifdef ASSERT
3166 trailing->_pair_idx = leading->_idx;
3167 leading->_pair_idx = leading->_idx;
3168 #endif
3169 }
3170
3171 void MemBarNode::set_load_store_pair(MemBarNode* leading, MemBarNode* trailing) {
3172 trailing->_kind = TrailingLoadStore;
3173 leading->_kind = LeadingLoadStore;
3174 #ifdef ASSERT
3175 trailing->_pair_idx = leading->_idx;
3176 leading->_pair_idx = leading->_idx;
3177 #endif
3178 }
3179
3180 MemBarNode* MemBarNode::trailing_membar() const {
3181 ResourceMark rm;
3182 Node* trailing = (Node*)this;
3183 VectorSet seen(Thread::current()->resource_area());
3184 Node_Stack multis(0);
3185 do {
3186 Node* c = trailing;
3187 uint i = 0;
3188 do {
3189 trailing = NULL;
3190 for (; i < c->outcnt(); i++) {
3191 Node* next = c->raw_out(i);
3192 if (next != c && next->is_CFG()) {
3193 if (c->is_MultiBranch()) {
3194 if (multis.node() == c) {
3195 multis.set_index(i+1);
3196 } else {
3197 multis.push(c, i+1);
3198 }
3199 }
3200 trailing = next;
3201 break;
3202 }
3203 }
3204 if (trailing != NULL && !seen.test_set(trailing->_idx)) {
3205 break;
3206 }
3207 while (multis.size() > 0) {
3208 c = multis.node();
3209 i = multis.index();
3210 if (i < c->req()) {
3211 break;
3212 }
3213 multis.pop();
3214 }
3215 } while (multis.size() > 0);
3216 } while (!trailing->is_MemBar() || !trailing->as_MemBar()->trailing());
3217
3218 MemBarNode* mb = trailing->as_MemBar();
3219 assert((mb->_kind == TrailingStore && _kind == LeadingStore) ||
3220 (mb->_kind == TrailingLoadStore && _kind == LeadingLoadStore), "bad trailing membar");
3221 assert(mb->_pair_idx == _pair_idx, "bad trailing membar");
3222 return mb;
3223 }
3224
3225 MemBarNode* MemBarNode::leading_membar() const {
3226 ResourceMark rm;
3227 VectorSet seen(Thread::current()->resource_area());
3228 Node_Stack regions(0);
3229 Node* leading = in(0);
3230 while (leading != NULL && (!leading->is_MemBar() || !leading->as_MemBar()->leading())) {
3231 while (leading == NULL || leading->is_top() || seen.test_set(leading->_idx)) {
3232 leading = NULL;
3233 while (regions.size() > 0) {
3234 Node* r = regions.node();
3235 uint i = regions.index();
3236 if (i < r->req()) {
3237 leading = r->in(i);
3238 regions.set_index(i+1);
3239 } else {
3240 regions.pop();
3241 }
3242 }
3243 if (leading == NULL) {
3244 assert(regions.size() == 0, "all paths should have been tried");
3245 return NULL;
3246 }
3247 }
3248 if (leading->is_Region()) {
3249 regions.push(leading, 2);
3250 leading = leading->in(1);
3251 } else {
3252 leading = leading->in(0);
3253 }
3254 }
3255 #ifdef ASSERT
3256 Unique_Node_List wq;
3257 wq.push((Node*)this);
3258 uint found = 0;
3259 for (uint i = 0; i < wq.size(); i++) {
3260 Node* n = wq.at(i);
3261 if (n->is_Region()) {
3262 for (uint j = 1; j < n->req(); j++) {
3263 Node* in = n->in(j);
3264 if (in != NULL && !in->is_top()) {
3265 wq.push(in);
3266 }
3267 }
3268 } else {
3269 if (n->is_MemBar() && n->as_MemBar()->leading()) {
3270 assert(n == leading, "consistency check failed");
3271 found++;
3272 } else {
3273 Node* in = n->in(0);
3274 if (in != NULL && !in->is_top()) {
3275 wq.push(in);
3276 }
3277 }
3278 }
3279 }
3280 assert(found == 1 || (found == 0 && leading == NULL), "consistency check failed");
3281 #endif
3282 if (leading == NULL) {
3283 return NULL;
3284 }
3285 MemBarNode* mb = leading->as_MemBar();
3286 assert((mb->_kind == LeadingStore && _kind == TrailingStore) ||
3287 (mb->_kind == LeadingLoadStore && _kind == TrailingLoadStore), "bad leading membar");
3288 assert(mb->_pair_idx == _pair_idx, "bad leading membar");
3289 return mb;
3290 }
3291
3292 //===========================InitializeNode====================================
3293 // SUMMARY:
3294 // This node acts as a memory barrier on raw memory, after some raw stores.
3295 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
3296 // The Initialize can 'capture' suitably constrained stores as raw inits.
3297 // It can coalesce related raw stores into larger units (called 'tiles').
3298 // It can avoid zeroing new storage for memory units which have raw inits.
3299 // At macro-expansion, it is marked 'complete', and does not optimize further.
3300 //
3301 // EXAMPLE:
3302 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
3303 // ctl = incoming control; mem* = incoming memory
3304 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
3305 // First allocate uninitialized memory and fill in the header:
3306 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
3307 // ctl := alloc.Control; mem* := alloc.Memory*
3308 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
3309 // Then initialize to zero the non-header parts of the raw memory block:
3310 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
3311 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
3312 // After the initialize node executes, the object is ready for service:
3313 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
3314 // Suppose its body is immediately initialized as {1,2}:
3315 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3316 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3317 // mem.SLICE(#short[*]) := store2
3318 //
3319 // DETAILS:
3320 // An InitializeNode collects and isolates object initialization after
3321 // an AllocateNode and before the next possible safepoint. As a
3322 // memory barrier (MemBarNode), it keeps critical stores from drifting
3323 // down past any safepoint or any publication of the allocation.
3324 // Before this barrier, a newly-allocated object may have uninitialized bits.
3325 // After this barrier, it may be treated as a real oop, and GC is allowed.
3326 //
3327 // The semantics of the InitializeNode include an implicit zeroing of
3328 // the new object from object header to the end of the object.
3329 // (The object header and end are determined by the AllocateNode.)
3330 //
3331 // Certain stores may be added as direct inputs to the InitializeNode.
3332 // These stores must update raw memory, and they must be to addresses
3333 // derived from the raw address produced by AllocateNode, and with
3334 // a constant offset. They must be ordered by increasing offset.
3335 // The first one is at in(RawStores), the last at in(req()-1).
3336 // Unlike most memory operations, they are not linked in a chain,
3337 // but are displayed in parallel as users of the rawmem output of
3338 // the allocation.
3339 //
3340 // (See comments in InitializeNode::capture_store, which continue
3341 // the example given above.)
3342 //
3343 // When the associated Allocate is macro-expanded, the InitializeNode
3344 // may be rewritten to optimize collected stores. A ClearArrayNode
3345 // may also be created at that point to represent any required zeroing.
3346 // The InitializeNode is then marked 'complete', prohibiting further
3347 // capturing of nearby memory operations.
3348 //
3349 // During macro-expansion, all captured initializations which store
3350 // constant values of 32 bits or smaller are coalesced (if advantageous)
3351 // into larger 'tiles' 32 or 64 bits. This allows an object to be
3352 // initialized in fewer memory operations. Memory words which are
3353 // covered by neither tiles nor non-constant stores are pre-zeroed
3354 // by explicit stores of zero. (The code shape happens to do all
3355 // zeroing first, then all other stores, with both sequences occurring
3356 // in order of ascending offsets.)
3357 //
3358 // Alternatively, code may be inserted between an AllocateNode and its
3359 // InitializeNode, to perform arbitrary initialization of the new object.
3360 // E.g., the object copying intrinsics insert complex data transfers here.
3361 // The initialization must then be marked as 'complete' disable the
3362 // built-in zeroing semantics and the collection of initializing stores.
3363 //
3364 // While an InitializeNode is incomplete, reads from the memory state
3365 // produced by it are optimizable if they match the control edge and
3366 // new oop address associated with the allocation/initialization.
3367 // They return a stored value (if the offset matches) or else zero.
3368 // A write to the memory state, if it matches control and address,
3369 // and if it is to a constant offset, may be 'captured' by the
3370 // InitializeNode. It is cloned as a raw memory operation and rewired
3371 // inside the initialization, to the raw oop produced by the allocation.
3372 // Operations on addresses which are provably distinct (e.g., to
3373 // other AllocateNodes) are allowed to bypass the initialization.
3374 //
3375 // The effect of all this is to consolidate object initialization
3376 // (both arrays and non-arrays, both piecewise and bulk) into a
3377 // single location, where it can be optimized as a unit.
3378 //
3379 // Only stores with an offset less than TrackedInitializationLimit words
3380 // will be considered for capture by an InitializeNode. This puts a
3381 // reasonable limit on the complexity of optimized initializations.
3382
3383 //---------------------------InitializeNode------------------------------------
3384 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
3385 : MemBarNode(C, adr_type, rawoop),
3386 _is_complete(Incomplete), _does_not_escape(false)
3387 {
3388 init_class_id(Class_Initialize);
3389
3390 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
3391 assert(in(RawAddress) == rawoop, "proper init");
3392 // Note: allocation() can be NULL, for secondary initialization barriers
3393 }
3394
3395 // Since this node is not matched, it will be processed by the
3396 // register allocator. Declare that there are no constraints
3397 // on the allocation of the RawAddress edge.
3398 const RegMask &InitializeNode::in_RegMask(uint idx) const {
3399 // This edge should be set to top, by the set_complete. But be conservative.
3400 if (idx == InitializeNode::RawAddress)
3401 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
3402 return RegMask::Empty;
3403 }
3404
3405 Node* InitializeNode::memory(uint alias_idx) {
3406 Node* mem = in(Memory);
3407 if (mem->is_MergeMem()) {
3408 return mem->as_MergeMem()->memory_at(alias_idx);
3409 } else {
3410 // incoming raw memory is not split
3411 return mem;
3412 }
3413 }
3414
3415 bool InitializeNode::is_non_zero() {
3416 if (is_complete()) return false;
3417 remove_extra_zeroes();
3418 return (req() > RawStores);
3419 }
3420
3421 void InitializeNode::set_complete(PhaseGVN* phase) {
3422 assert(!is_complete(), "caller responsibility");
3423 _is_complete = Complete;
3424
3425 // After this node is complete, it contains a bunch of
3426 // raw-memory initializations. There is no need for
3427 // it to have anything to do with non-raw memory effects.
3428 // Therefore, tell all non-raw users to re-optimize themselves,
3429 // after skipping the memory effects of this initialization.
3430 PhaseIterGVN* igvn = phase->is_IterGVN();
3431 if (igvn) igvn->add_users_to_worklist(this);
3432 }
3433
3434 // convenience function
3435 // return false if the init contains any stores already
3436 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
3437 InitializeNode* init = initialization();
3438 if (init == NULL || init->is_complete()) return false;
3439 init->remove_extra_zeroes();
3440 // for now, if this allocation has already collected any inits, bail:
3441 if (init->is_non_zero()) return false;
3442 init->set_complete(phase);
3443 return true;
3444 }
3445
3446 void InitializeNode::remove_extra_zeroes() {
3447 if (req() == RawStores) return;
3448 Node* zmem = zero_memory();
3449 uint fill = RawStores;
3450 for (uint i = fill; i < req(); i++) {
3451 Node* n = in(i);
3452 if (n->is_top() || n == zmem) continue; // skip
3453 if (fill < i) set_req(fill, n); // compact
3454 ++fill;
3455 }
3456 // delete any empty spaces created:
3457 while (fill < req()) {
3458 del_req(fill);
3459 }
3460 }
3461
3462 // Helper for remembering which stores go with which offsets.
3463 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) {
3464 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
3465 intptr_t offset = -1;
3466 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
3467 phase, offset);
3468 if (base == NULL) return -1; // something is dead,
3469 if (offset < 0) return -1; // dead, dead
3470 return offset;
3471 }
3472
3473 // Helper for proving that an initialization expression is
3474 // "simple enough" to be folded into an object initialization.
3475 // Attempts to prove that a store's initial value 'n' can be captured
3476 // within the initialization without creating a vicious cycle, such as:
3477 // { Foo p = new Foo(); p.next = p; }
3478 // True for constants and parameters and small combinations thereof.
3479 bool InitializeNode::detect_init_independence(Node* n, int& count) {
3480 if (n == NULL) return true; // (can this really happen?)
3481 if (n->is_Proj()) n = n->in(0);
3482 if (n == this) return false; // found a cycle
3483 if (n->is_Con()) return true;
3484 if (n->is_Start()) return true; // params, etc., are OK
3485 if (n->is_Root()) return true; // even better
3486
3487 Node* ctl = n->in(0);
3488 if (ctl != NULL && !ctl->is_top()) {
3489 if (ctl->is_Proj()) ctl = ctl->in(0);
3490 if (ctl == this) return false;
3491
3492 // If we already know that the enclosing memory op is pinned right after
3493 // the init, then any control flow that the store has picked up
3494 // must have preceded the init, or else be equal to the init.
3495 // Even after loop optimizations (which might change control edges)
3496 // a store is never pinned *before* the availability of its inputs.
3497 if (!MemNode::all_controls_dominate(n, this))
3498 return false; // failed to prove a good control
3499 }
3500
3501 // Check data edges for possible dependencies on 'this'.
3502 if ((count += 1) > 20) return false; // complexity limit
3503 for (uint i = 1; i < n->req(); i++) {
3504 Node* m = n->in(i);
3505 if (m == NULL || m == n || m->is_top()) continue;
3506 uint first_i = n->find_edge(m);
3507 if (i != first_i) continue; // process duplicate edge just once
3508 if (!detect_init_independence(m, count)) {
3509 return false;
3510 }
3511 }
3512
3513 return true;
3514 }
3515
3516 // Here are all the checks a Store must pass before it can be moved into
3517 // an initialization. Returns zero if a check fails.
3518 // On success, returns the (constant) offset to which the store applies,
3519 // within the initialized memory.
3520 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase, bool can_reshape) {
3521 const int FAIL = 0;
3522 if (st->is_unaligned_access()) {
3523 return FAIL;
3524 }
3525 if (st->req() != MemNode::ValueIn + 1)
3526 return FAIL; // an inscrutable StoreNode (card mark?)
3527 Node* ctl = st->in(MemNode::Control);
3528 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this))
3529 return FAIL; // must be unconditional after the initialization
3530 Node* mem = st->in(MemNode::Memory);
3531 if (!(mem->is_Proj() && mem->in(0) == this))
3532 return FAIL; // must not be preceded by other stores
3533 Node* adr = st->in(MemNode::Address);
3534 intptr_t offset;
3535 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
3536 if (alloc == NULL)
3537 return FAIL; // inscrutable address
3538 if (alloc != allocation())
3539 return FAIL; // wrong allocation! (store needs to float up)
3540 Node* val = st->in(MemNode::ValueIn);
3541 int complexity_count = 0;
3542 if (!detect_init_independence(val, complexity_count))
3543 return FAIL; // stored value must be 'simple enough'
3544
3545 // The Store can be captured only if nothing after the allocation
3546 // and before the Store is using the memory location that the store
3547 // overwrites.
3548 bool failed = false;
3549 // If is_complete_with_arraycopy() is true the shape of the graph is
3550 // well defined and is safe so no need for extra checks.
3551 if (!is_complete_with_arraycopy()) {
3552 // We are going to look at each use of the memory state following
3553 // the allocation to make sure nothing reads the memory that the
3554 // Store writes.
3555 const TypePtr* t_adr = phase->type(adr)->isa_ptr();
3556 int alias_idx = phase->C->get_alias_index(t_adr);
3557 ResourceMark rm;
3558 Unique_Node_List mems;
3559 mems.push(mem);
3560 Node* unique_merge = NULL;
3561 for (uint next = 0; next < mems.size(); ++next) {
3562 Node *m = mems.at(next);
3563 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
3564 Node *n = m->fast_out(j);
3565 if (n->outcnt() == 0) {
3566 continue;
3567 }
3568 if (n == st) {
3569 continue;
3570 } else if (n->in(0) != NULL && n->in(0) != ctl) {
3571 // If the control of this use is different from the control
3572 // of the Store which is right after the InitializeNode then
3573 // this node cannot be between the InitializeNode and the
3574 // Store.
3575 continue;
3576 } else if (n->is_MergeMem()) {
3577 if (n->as_MergeMem()->memory_at(alias_idx) == m) {
3578 // We can hit a MergeMemNode (that will likely go away
3579 // later) that is a direct use of the memory state
3580 // following the InitializeNode on the same slice as the
3581 // store node that we'd like to capture. We need to check
3582 // the uses of the MergeMemNode.
3583 mems.push(n);
3584 }
3585 } else if (n->is_Mem()) {
3586 Node* other_adr = n->in(MemNode::Address);
3587 if (other_adr == adr) {
3588 failed = true;
3589 break;
3590 } else {
3591 const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr();
3592 if (other_t_adr != NULL) {
3593 int other_alias_idx = phase->C->get_alias_index(other_t_adr);
3594 if (other_alias_idx == alias_idx) {
3595 // A load from the same memory slice as the store right
3596 // after the InitializeNode. We check the control of the
3597 // object/array that is loaded from. If it's the same as
3598 // the store control then we cannot capture the store.
3599 assert(!n->is_Store(), "2 stores to same slice on same control?");
3600 Node* base = other_adr;
3601 assert(base->is_AddP(), "should be addp but is %s", base->Name());
3602 base = base->in(AddPNode::Base);
3603 if (base != NULL) {
3604 base = base->uncast();
3605 if (base->is_Proj() && base->in(0) == alloc) {
3606 failed = true;
3607 break;
3608 }
3609 }
3610 }
3611 }
3612 }
3613 } else {
3614 failed = true;
3615 break;
3616 }
3617 }
3618 }
3619 }
3620 if (failed) {
3621 if (!can_reshape) {
3622 // We decided we couldn't capture the store during parsing. We
3623 // should try again during the next IGVN once the graph is
3624 // cleaner.
3625 phase->C->record_for_igvn(st);
3626 }
3627 return FAIL;
3628 }
3629
3630 return offset; // success
3631 }
3632
3633 // Find the captured store in(i) which corresponds to the range
3634 // [start..start+size) in the initialized object.
3635 // If there is one, return its index i. If there isn't, return the
3636 // negative of the index where it should be inserted.
3637 // Return 0 if the queried range overlaps an initialization boundary
3638 // or if dead code is encountered.
3639 // If size_in_bytes is zero, do not bother with overlap checks.
3640 int InitializeNode::captured_store_insertion_point(intptr_t start,
3641 int size_in_bytes,
3642 PhaseTransform* phase) {
3643 const int FAIL = 0, MAX_STORE = BytesPerLong;
3644
3645 if (is_complete())
3646 return FAIL; // arraycopy got here first; punt
3647
3648 assert(allocation() != NULL, "must be present");
3649
3650 // no negatives, no header fields:
3651 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
3652
3653 // after a certain size, we bail out on tracking all the stores:
3654 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3655 if (start >= ti_limit) return FAIL;
3656
3657 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
3658 if (i >= limit) return -(int)i; // not found; here is where to put it
3659
3660 Node* st = in(i);
3661 intptr_t st_off = get_store_offset(st, phase);
3662 if (st_off < 0) {
3663 if (st != zero_memory()) {
3664 return FAIL; // bail out if there is dead garbage
3665 }
3666 } else if (st_off > start) {
3667 // ...we are done, since stores are ordered
3668 if (st_off < start + size_in_bytes) {
3669 return FAIL; // the next store overlaps
3670 }
3671 return -(int)i; // not found; here is where to put it
3672 } else if (st_off < start) {
3673 if (size_in_bytes != 0 &&
3674 start < st_off + MAX_STORE &&
3675 start < st_off + st->as_Store()->memory_size()) {
3676 return FAIL; // the previous store overlaps
3677 }
3678 } else {
3679 if (size_in_bytes != 0 &&
3680 st->as_Store()->memory_size() != size_in_bytes) {
3681 return FAIL; // mismatched store size
3682 }
3683 return i;
3684 }
3685
3686 ++i;
3687 }
3688 }
3689
3690 // Look for a captured store which initializes at the offset 'start'
3691 // with the given size. If there is no such store, and no other
3692 // initialization interferes, then return zero_memory (the memory
3693 // projection of the AllocateNode).
3694 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
3695 PhaseTransform* phase) {
3696 assert(stores_are_sane(phase), "");
3697 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3698 if (i == 0) {
3699 return NULL; // something is dead
3700 } else if (i < 0) {
3701 return zero_memory(); // just primordial zero bits here
3702 } else {
3703 Node* st = in(i); // here is the store at this position
3704 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
3705 return st;
3706 }
3707 }
3708
3709 // Create, as a raw pointer, an address within my new object at 'offset'.
3710 Node* InitializeNode::make_raw_address(intptr_t offset,
3711 PhaseTransform* phase) {
3712 Node* addr = in(RawAddress);
3713 if (offset != 0) {
3714 Compile* C = phase->C;
3715 addr = phase->transform( new AddPNode(C->top(), addr,
3716 phase->MakeConX(offset)) );
3717 }
3718 return addr;
3719 }
3720
3721 // Clone the given store, converting it into a raw store
3722 // initializing a field or element of my new object.
3723 // Caller is responsible for retiring the original store,
3724 // with subsume_node or the like.
3725 //
3726 // From the example above InitializeNode::InitializeNode,
3727 // here are the old stores to be captured:
3728 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3729 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3730 //
3731 // Here is the changed code; note the extra edges on init:
3732 // alloc = (Allocate ...)
3733 // rawoop = alloc.RawAddress
3734 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
3735 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
3736 // init = (Initialize alloc.Control alloc.Memory rawoop
3737 // rawstore1 rawstore2)
3738 //
3739 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
3740 PhaseTransform* phase, bool can_reshape) {
3741 assert(stores_are_sane(phase), "");
3742
3743 if (start < 0) return NULL;
3744 assert(can_capture_store(st, phase, can_reshape) == start, "sanity");
3745
3746 Compile* C = phase->C;
3747 int size_in_bytes = st->memory_size();
3748 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3749 if (i == 0) return NULL; // bail out
3750 Node* prev_mem = NULL; // raw memory for the captured store
3751 if (i > 0) {
3752 prev_mem = in(i); // there is a pre-existing store under this one
3753 set_req(i, C->top()); // temporarily disconnect it
3754 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
3755 } else {
3756 i = -i; // no pre-existing store
3757 prev_mem = zero_memory(); // a slice of the newly allocated object
3758 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
3759 set_req(--i, C->top()); // reuse this edge; it has been folded away
3760 else
3761 ins_req(i, C->top()); // build a new edge
3762 }
3763 Node* new_st = st->clone();
3764 new_st->set_req(MemNode::Control, in(Control));
3765 new_st->set_req(MemNode::Memory, prev_mem);
3766 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
3767 new_st = phase->transform(new_st);
3768
3769 // At this point, new_st might have swallowed a pre-existing store
3770 // at the same offset, or perhaps new_st might have disappeared,
3771 // if it redundantly stored the same value (or zero to fresh memory).
3772
3773 // In any case, wire it in:
3774 phase->igvn_rehash_node_delayed(this);
3775 set_req(i, new_st);
3776
3777 // The caller may now kill the old guy.
3778 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
3779 assert(check_st == new_st || check_st == NULL, "must be findable");
3780 assert(!is_complete(), "");
3781 return new_st;
3782 }
3783
3784 static bool store_constant(jlong* tiles, int num_tiles,
3785 intptr_t st_off, int st_size,
3786 jlong con) {
3787 if ((st_off & (st_size-1)) != 0)
3788 return false; // strange store offset (assume size==2**N)
3789 address addr = (address)tiles + st_off;
3790 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
3791 switch (st_size) {
3792 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
3793 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
3794 case sizeof(jint): *(jint*) addr = (jint) con; break;
3795 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
3796 default: return false; // strange store size (detect size!=2**N here)
3797 }
3798 return true; // return success to caller
3799 }
3800
3801 // Coalesce subword constants into int constants and possibly
3802 // into long constants. The goal, if the CPU permits,
3803 // is to initialize the object with a small number of 64-bit tiles.
3804 // Also, convert floating-point constants to bit patterns.
3805 // Non-constants are not relevant to this pass.
3806 //
3807 // In terms of the running example on InitializeNode::InitializeNode
3808 // and InitializeNode::capture_store, here is the transformation
3809 // of rawstore1 and rawstore2 into rawstore12:
3810 // alloc = (Allocate ...)
3811 // rawoop = alloc.RawAddress
3812 // tile12 = 0x00010002
3813 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
3814 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
3815 //
3816 void
3817 InitializeNode::coalesce_subword_stores(intptr_t header_size,
3818 Node* size_in_bytes,
3819 PhaseGVN* phase) {
3820 Compile* C = phase->C;
3821
3822 assert(stores_are_sane(phase), "");
3823 // Note: After this pass, they are not completely sane,
3824 // since there may be some overlaps.
3825
3826 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
3827
3828 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3829 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
3830 size_limit = MIN2(size_limit, ti_limit);
3831 size_limit = align_up(size_limit, BytesPerLong);
3832 int num_tiles = size_limit / BytesPerLong;
3833
3834 // allocate space for the tile map:
3835 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
3836 jlong tiles_buf[small_len];
3837 Node* nodes_buf[small_len];
3838 jlong inits_buf[small_len];
3839 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
3840 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3841 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
3842 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
3843 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
3844 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3845 // tiles: exact bitwise model of all primitive constants
3846 // nodes: last constant-storing node subsumed into the tiles model
3847 // inits: which bytes (in each tile) are touched by any initializations
3848
3849 //// Pass A: Fill in the tile model with any relevant stores.
3850
3851 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
3852 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
3853 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
3854 Node* zmem = zero_memory(); // initially zero memory state
3855 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3856 Node* st = in(i);
3857 intptr_t st_off = get_store_offset(st, phase);
3858
3859 // Figure out the store's offset and constant value:
3860 if (st_off < header_size) continue; //skip (ignore header)
3861 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
3862 int st_size = st->as_Store()->memory_size();
3863 if (st_off + st_size > size_limit) break;
3864
3865 // Record which bytes are touched, whether by constant or not.
3866 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
3867 continue; // skip (strange store size)
3868
3869 const Type* val = phase->type(st->in(MemNode::ValueIn));
3870 if (!val->singleton()) continue; //skip (non-con store)
3871 BasicType type = val->basic_type();
3872
3873 jlong con = 0;
3874 switch (type) {
3875 case T_INT: con = val->is_int()->get_con(); break;
3876 case T_LONG: con = val->is_long()->get_con(); break;
3877 case T_FLOAT: con = jint_cast(val->getf()); break;
3878 case T_DOUBLE: con = jlong_cast(val->getd()); break;
3879 default: continue; //skip (odd store type)
3880 }
3881
3882 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
3883 st->Opcode() == Op_StoreL) {
3884 continue; // This StoreL is already optimal.
3885 }
3886
3887 // Store down the constant.
3888 store_constant(tiles, num_tiles, st_off, st_size, con);
3889
3890 intptr_t j = st_off >> LogBytesPerLong;
3891
3892 if (type == T_INT && st_size == BytesPerInt
3893 && (st_off & BytesPerInt) == BytesPerInt) {
3894 jlong lcon = tiles[j];
3895 if (!Matcher::isSimpleConstant64(lcon) &&
3896 st->Opcode() == Op_StoreI) {
3897 // This StoreI is already optimal by itself.
3898 jint* intcon = (jint*) &tiles[j];
3899 intcon[1] = 0; // undo the store_constant()
3900
3901 // If the previous store is also optimal by itself, back up and
3902 // undo the action of the previous loop iteration... if we can.
3903 // But if we can't, just let the previous half take care of itself.
3904 st = nodes[j];
3905 st_off -= BytesPerInt;
3906 con = intcon[0];
3907 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) {
3908 assert(st_off >= header_size, "still ignoring header");
3909 assert(get_store_offset(st, phase) == st_off, "must be");
3910 assert(in(i-1) == zmem, "must be");
3911 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
3912 assert(con == tcon->is_int()->get_con(), "must be");
3913 // Undo the effects of the previous loop trip, which swallowed st:
3914 intcon[0] = 0; // undo store_constant()
3915 set_req(i-1, st); // undo set_req(i, zmem)
3916 nodes[j] = NULL; // undo nodes[j] = st
3917 --old_subword; // undo ++old_subword
3918 }
3919 continue; // This StoreI is already optimal.
3920 }
3921 }
3922
3923 // This store is not needed.
3924 set_req(i, zmem);
3925 nodes[j] = st; // record for the moment
3926 if (st_size < BytesPerLong) // something has changed
3927 ++old_subword; // includes int/float, but who's counting...
3928 else ++old_long;
3929 }
3930
3931 if ((old_subword + old_long) == 0)
3932 return; // nothing more to do
3933
3934 //// Pass B: Convert any non-zero tiles into optimal constant stores.
3935 // Be sure to insert them before overlapping non-constant stores.
3936 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
3937 for (int j = 0; j < num_tiles; j++) {
3938 jlong con = tiles[j];
3939 jlong init = inits[j];
3940 if (con == 0) continue;
3941 jint con0, con1; // split the constant, address-wise
3942 jint init0, init1; // split the init map, address-wise
3943 { union { jlong con; jint intcon[2]; } u;
3944 u.con = con;
3945 con0 = u.intcon[0];
3946 con1 = u.intcon[1];
3947 u.con = init;
3948 init0 = u.intcon[0];
3949 init1 = u.intcon[1];
3950 }
3951
3952 Node* old = nodes[j];
3953 assert(old != NULL, "need the prior store");
3954 intptr_t offset = (j * BytesPerLong);
3955
3956 bool split = !Matcher::isSimpleConstant64(con);
3957
3958 if (offset < header_size) {
3959 assert(offset + BytesPerInt >= header_size, "second int counts");
3960 assert(*(jint*)&tiles[j] == 0, "junk in header");
3961 split = true; // only the second word counts
3962 // Example: int a[] = { 42 ... }
3963 } else if (con0 == 0 && init0 == -1) {
3964 split = true; // first word is covered by full inits
3965 // Example: int a[] = { ... foo(), 42 ... }
3966 } else if (con1 == 0 && init1 == -1) {
3967 split = true; // second word is covered by full inits
3968 // Example: int a[] = { ... 42, foo() ... }
3969 }
3970
3971 // Here's a case where init0 is neither 0 nor -1:
3972 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
3973 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
3974 // In this case the tile is not split; it is (jlong)42.
3975 // The big tile is stored down, and then the foo() value is inserted.
3976 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
3977
3978 Node* ctl = old->in(MemNode::Control);
3979 Node* adr = make_raw_address(offset, phase);
3980 const TypePtr* atp = TypeRawPtr::BOTTOM;
3981
3982 // One or two coalesced stores to plop down.
3983 Node* st[2];
3984 intptr_t off[2];
3985 int nst = 0;
3986 if (!split) {
3987 ++new_long;
3988 off[nst] = offset;
3989 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3990 phase->longcon(con), T_LONG, MemNode::unordered);
3991 } else {
3992 // Omit either if it is a zero.
3993 if (con0 != 0) {
3994 ++new_int;
3995 off[nst] = offset;
3996 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3997 phase->intcon(con0), T_INT, MemNode::unordered);
3998 }
3999 if (con1 != 0) {
4000 ++new_int;
4001 offset += BytesPerInt;
4002 adr = make_raw_address(offset, phase);
4003 off[nst] = offset;
4004 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
4005 phase->intcon(con1), T_INT, MemNode::unordered);
4006 }
4007 }
4008
4009 // Insert second store first, then the first before the second.
4010 // Insert each one just before any overlapping non-constant stores.
4011 while (nst > 0) {
4012 Node* st1 = st[--nst];
4013 C->copy_node_notes_to(st1, old);
4014 st1 = phase->transform(st1);
4015 offset = off[nst];
4016 assert(offset >= header_size, "do not smash header");
4017 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
4018 guarantee(ins_idx != 0, "must re-insert constant store");
4019 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
4020 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
4021 set_req(--ins_idx, st1);
4022 else
4023 ins_req(ins_idx, st1);
4024 }
4025 }
4026
4027 if (PrintCompilation && WizardMode)
4028 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
4029 old_subword, old_long, new_int, new_long);
4030 if (C->log() != NULL)
4031 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
4032 old_subword, old_long, new_int, new_long);
4033
4034 // Clean up any remaining occurrences of zmem:
4035 remove_extra_zeroes();
4036 }
4037
4038 // Explore forward from in(start) to find the first fully initialized
4039 // word, and return its offset. Skip groups of subword stores which
4040 // together initialize full words. If in(start) is itself part of a
4041 // fully initialized word, return the offset of in(start). If there
4042 // are no following full-word stores, or if something is fishy, return
4043 // a negative value.
4044 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
4045 int int_map = 0;
4046 intptr_t int_map_off = 0;
4047 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
4048
4049 for (uint i = start, limit = req(); i < limit; i++) {
4050 Node* st = in(i);
4051
4052 intptr_t st_off = get_store_offset(st, phase);
4053 if (st_off < 0) break; // return conservative answer
4054
4055 int st_size = st->as_Store()->memory_size();
4056 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
4057 return st_off; // we found a complete word init
4058 }
4059
4060 // update the map:
4061
4062 intptr_t this_int_off = align_down(st_off, BytesPerInt);
4063 if (this_int_off != int_map_off) {
4064 // reset the map:
4065 int_map = 0;
4066 int_map_off = this_int_off;
4067 }
4068
4069 int subword_off = st_off - this_int_off;
4070 int_map |= right_n_bits(st_size) << subword_off;
4071 if ((int_map & FULL_MAP) == FULL_MAP) {
4072 return this_int_off; // we found a complete word init
4073 }
4074
4075 // Did this store hit or cross the word boundary?
4076 intptr_t next_int_off = align_down(st_off + st_size, BytesPerInt);
4077 if (next_int_off == this_int_off + BytesPerInt) {
4078 // We passed the current int, without fully initializing it.
4079 int_map_off = next_int_off;
4080 int_map >>= BytesPerInt;
4081 } else if (next_int_off > this_int_off + BytesPerInt) {
4082 // We passed the current and next int.
4083 return this_int_off + BytesPerInt;
4084 }
4085 }
4086
4087 return -1;
4088 }
4089
4090
4091 // Called when the associated AllocateNode is expanded into CFG.
4092 // At this point, we may perform additional optimizations.
4093 // Linearize the stores by ascending offset, to make memory
4094 // activity as coherent as possible.
4095 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
4096 intptr_t header_size,
4097 Node* size_in_bytes,
4098 PhaseGVN* phase) {
4099 assert(!is_complete(), "not already complete");
4100 assert(stores_are_sane(phase), "");
4101 assert(allocation() != NULL, "must be present");
4102
4103 remove_extra_zeroes();
4104
4105 if (ReduceFieldZeroing || ReduceBulkZeroing)
4106 // reduce instruction count for common initialization patterns
4107 coalesce_subword_stores(header_size, size_in_bytes, phase);
4108
4109 Node* zmem = zero_memory(); // initially zero memory state
4110 Node* inits = zmem; // accumulating a linearized chain of inits
4111 #ifdef ASSERT
4112 intptr_t first_offset = allocation()->minimum_header_size();
4113 intptr_t last_init_off = first_offset; // previous init offset
4114 intptr_t last_init_end = first_offset; // previous init offset+size
4115 intptr_t last_tile_end = first_offset; // previous tile offset+size
4116 #endif
4117 intptr_t zeroes_done = header_size;
4118
4119 bool do_zeroing = true; // we might give up if inits are very sparse
4120 int big_init_gaps = 0; // how many large gaps have we seen?
4121
4122 if (UseTLAB && ZeroTLAB) do_zeroing = false;
4123 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
4124
4125 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
4126 Node* st = in(i);
4127 intptr_t st_off = get_store_offset(st, phase);
4128 if (st_off < 0)
4129 break; // unknown junk in the inits
4130 if (st->in(MemNode::Memory) != zmem)
4131 break; // complicated store chains somehow in list
4132
4133 int st_size = st->as_Store()->memory_size();
4134 intptr_t next_init_off = st_off + st_size;
4135
4136 if (do_zeroing && zeroes_done < next_init_off) {
4137 // See if this store needs a zero before it or under it.
4138 intptr_t zeroes_needed = st_off;
4139
4140 if (st_size < BytesPerInt) {
4141 // Look for subword stores which only partially initialize words.
4142 // If we find some, we must lay down some word-level zeroes first,
4143 // underneath the subword stores.
4144 //
4145 // Examples:
4146 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
4147 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
4148 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
4149 //
4150 // Note: coalesce_subword_stores may have already done this,
4151 // if it was prompted by constant non-zero subword initializers.
4152 // But this case can still arise with non-constant stores.
4153
4154 intptr_t next_full_store = find_next_fullword_store(i, phase);
4155
4156 // In the examples above:
4157 // in(i) p q r s x y z
4158 // st_off 12 13 14 15 12 13 14
4159 // st_size 1 1 1 1 1 1 1
4160 // next_full_s. 12 16 16 16 16 16 16
4161 // z's_done 12 16 16 16 12 16 12
4162 // z's_needed 12 16 16 16 16 16 16
4163 // zsize 0 0 0 0 4 0 4
4164 if (next_full_store < 0) {
4165 // Conservative tack: Zero to end of current word.
4166 zeroes_needed = align_up(zeroes_needed, BytesPerInt);
4167 } else {
4168 // Zero to beginning of next fully initialized word.
4169 // Or, don't zero at all, if we are already in that word.
4170 assert(next_full_store >= zeroes_needed, "must go forward");
4171 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
4172 zeroes_needed = next_full_store;
4173 }
4174 }
4175
4176 if (zeroes_needed > zeroes_done) {
4177 intptr_t zsize = zeroes_needed - zeroes_done;
4178 // Do some incremental zeroing on rawmem, in parallel with inits.
4179 zeroes_done = align_down(zeroes_done, BytesPerInt);
4180 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
4181 zeroes_done, zeroes_needed,
4182 phase);
4183 zeroes_done = zeroes_needed;
4184 if (zsize > InitArrayShortSize && ++big_init_gaps > 2)
4185 do_zeroing = false; // leave the hole, next time
4186 }
4187 }
4188
4189 // Collect the store and move on:
4190 st->set_req(MemNode::Memory, inits);
4191 inits = st; // put it on the linearized chain
4192 set_req(i, zmem); // unhook from previous position
4193
4194 if (zeroes_done == st_off)
4195 zeroes_done = next_init_off;
4196
4197 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
4198
4199 #ifdef ASSERT
4200 // Various order invariants. Weaker than stores_are_sane because
4201 // a large constant tile can be filled in by smaller non-constant stores.
4202 assert(st_off >= last_init_off, "inits do not reverse");
4203 last_init_off = st_off;
4204 const Type* val = NULL;
4205 if (st_size >= BytesPerInt &&
4206 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
4207 (int)val->basic_type() < (int)T_OBJECT) {
4208 assert(st_off >= last_tile_end, "tiles do not overlap");
4209 assert(st_off >= last_init_end, "tiles do not overwrite inits");
4210 last_tile_end = MAX2(last_tile_end, next_init_off);
4211 } else {
4212 intptr_t st_tile_end = align_up(next_init_off, BytesPerLong);
4213 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
4214 assert(st_off >= last_init_end, "inits do not overlap");
4215 last_init_end = next_init_off; // it's a non-tile
4216 }
4217 #endif //ASSERT
4218 }
4219
4220 remove_extra_zeroes(); // clear out all the zmems left over
4221 add_req(inits);
4222
4223 if (!(UseTLAB && ZeroTLAB)) {
4224 // If anything remains to be zeroed, zero it all now.
4225 zeroes_done = align_down(zeroes_done, BytesPerInt);
4226 // if it is the last unused 4 bytes of an instance, forget about it
4227 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
4228 if (zeroes_done + BytesPerLong >= size_limit) {
4229 AllocateNode* alloc = allocation();
4230 assert(alloc != NULL, "must be present");
4231 if (alloc != NULL && alloc->Opcode() == Op_Allocate) {
4232 Node* klass_node = alloc->in(AllocateNode::KlassNode);
4233 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass();
4234 if (zeroes_done == k->layout_helper())
4235 zeroes_done = size_limit;
4236 }
4237 }
4238 if (zeroes_done < size_limit) {
4239 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
4240 zeroes_done, size_in_bytes, phase);
4241 }
4242 }
4243
4244 set_complete(phase);
4245 return rawmem;
4246 }
4247
4248
4249 #ifdef ASSERT
4250 bool InitializeNode::stores_are_sane(PhaseTransform* phase) {
4251 if (is_complete())
4252 return true; // stores could be anything at this point
4253 assert(allocation() != NULL, "must be present");
4254 intptr_t last_off = allocation()->minimum_header_size();
4255 for (uint i = InitializeNode::RawStores; i < req(); i++) {
4256 Node* st = in(i);
4257 intptr_t st_off = get_store_offset(st, phase);
4258 if (st_off < 0) continue; // ignore dead garbage
4259 if (last_off > st_off) {
4260 tty->print_cr("*** bad store offset at %d: " INTX_FORMAT " > " INTX_FORMAT, i, last_off, st_off);
4261 this->dump(2);
4262 assert(false, "ascending store offsets");
4263 return false;
4264 }
4265 last_off = st_off + st->as_Store()->memory_size();
4266 }
4267 return true;
4268 }
4269 #endif //ASSERT
4270
4271
4272
4273
4274 //============================MergeMemNode=====================================
4275 //
4276 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
4277 // contributing store or call operations. Each contributor provides the memory
4278 // state for a particular "alias type" (see Compile::alias_type). For example,
4279 // if a MergeMem has an input X for alias category #6, then any memory reference
4280 // to alias category #6 may use X as its memory state input, as an exact equivalent
4281 // to using the MergeMem as a whole.
4282 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
4283 //
4284 // (Here, the <N> notation gives the index of the relevant adr_type.)
4285 //
4286 // In one special case (and more cases in the future), alias categories overlap.
4287 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
4288 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
4289 // it is exactly equivalent to that state W:
4290 // MergeMem(<Bot>: W) <==> W
4291 //
4292 // Usually, the merge has more than one input. In that case, where inputs
4293 // overlap (i.e., one is Bot), the narrower alias type determines the memory
4294 // state for that type, and the wider alias type (Bot) fills in everywhere else:
4295 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
4296 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
4297 //
4298 // A merge can take a "wide" memory state as one of its narrow inputs.
4299 // This simply means that the merge observes out only the relevant parts of
4300 // the wide input. That is, wide memory states arriving at narrow merge inputs
4301 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
4302 //
4303 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
4304 // and that memory slices "leak through":
4305 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
4306 //
4307 // But, in such a cascade, repeated memory slices can "block the leak":
4308 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
4309 //
4310 // In the last example, Y is not part of the combined memory state of the
4311 // outermost MergeMem. The system must, of course, prevent unschedulable
4312 // memory states from arising, so you can be sure that the state Y is somehow
4313 // a precursor to state Y'.
4314 //
4315 //
4316 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
4317 // of each MergeMemNode array are exactly the numerical alias indexes, including
4318 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
4319 // Compile::alias_type (and kin) produce and manage these indexes.
4320 //
4321 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
4322 // (Note that this provides quick access to the top node inside MergeMem methods,
4323 // without the need to reach out via TLS to Compile::current.)
4324 //
4325 // As a consequence of what was just described, a MergeMem that represents a full
4326 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
4327 // containing all alias categories.
4328 //
4329 // MergeMem nodes never (?) have control inputs, so in(0) is NULL.
4330 //
4331 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
4332 // a memory state for the alias type <N>, or else the top node, meaning that
4333 // there is no particular input for that alias type. Note that the length of
4334 // a MergeMem is variable, and may be extended at any time to accommodate new
4335 // memory states at larger alias indexes. When merges grow, they are of course
4336 // filled with "top" in the unused in() positions.
4337 //
4338 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
4339 // (Top was chosen because it works smoothly with passes like GCM.)
4340 //
4341 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
4342 // the type of random VM bits like TLS references.) Since it is always the
4343 // first non-Bot memory slice, some low-level loops use it to initialize an
4344 // index variable: for (i = AliasIdxRaw; i < req(); i++).
4345 //
4346 //
4347 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
4348 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
4349 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
4350 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
4351 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
4352 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
4353 //
4354 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
4355 // really that different from the other memory inputs. An abbreviation called
4356 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
4357 //
4358 //
4359 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
4360 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
4361 // that "emerges though" the base memory will be marked as excluding the alias types
4362 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
4363 //
4364 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
4365 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
4366 //
4367 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
4368 // (It is currently unimplemented.) As you can see, the resulting merge is
4369 // actually a disjoint union of memory states, rather than an overlay.
4370 //
4371
4372 //------------------------------MergeMemNode-----------------------------------
4373 Node* MergeMemNode::make_empty_memory() {
4374 Node* empty_memory = (Node*) Compile::current()->top();
4375 assert(empty_memory->is_top(), "correct sentinel identity");
4376 return empty_memory;
4377 }
4378
4379 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
4380 init_class_id(Class_MergeMem);
4381 // all inputs are nullified in Node::Node(int)
4382 // set_input(0, NULL); // no control input
4383
4384 // Initialize the edges uniformly to top, for starters.
4385 Node* empty_mem = make_empty_memory();
4386 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
4387 init_req(i,empty_mem);
4388 }
4389 assert(empty_memory() == empty_mem, "");
4390
4391 if( new_base != NULL && new_base->is_MergeMem() ) {
4392 MergeMemNode* mdef = new_base->as_MergeMem();
4393 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
4394 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
4395 mms.set_memory(mms.memory2());
4396 }
4397 assert(base_memory() == mdef->base_memory(), "");
4398 } else {
4399 set_base_memory(new_base);
4400 }
4401 }
4402
4403 // Make a new, untransformed MergeMem with the same base as 'mem'.
4404 // If mem is itself a MergeMem, populate the result with the same edges.
4405 MergeMemNode* MergeMemNode::make(Node* mem) {
4406 return new MergeMemNode(mem);
4407 }
4408
4409 //------------------------------cmp--------------------------------------------
4410 uint MergeMemNode::hash() const { return NO_HASH; }
4411 uint MergeMemNode::cmp( const Node &n ) const {
4412 return (&n == this); // Always fail except on self
4413 }
4414
4415 //------------------------------Identity---------------------------------------
4416 Node* MergeMemNode::Identity(PhaseGVN* phase) {
4417 // Identity if this merge point does not record any interesting memory
4418 // disambiguations.
4419 Node* base_mem = base_memory();
4420 Node* empty_mem = empty_memory();
4421 if (base_mem != empty_mem) { // Memory path is not dead?
4422 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4423 Node* mem = in(i);
4424 if (mem != empty_mem && mem != base_mem) {
4425 return this; // Many memory splits; no change
4426 }
4427 }
4428 }
4429 return base_mem; // No memory splits; ID on the one true input
4430 }
4431
4432 //------------------------------Ideal------------------------------------------
4433 // This method is invoked recursively on chains of MergeMem nodes
4434 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4435 // Remove chain'd MergeMems
4436 //
4437 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
4438 // relative to the "in(Bot)". Since we are patching both at the same time,
4439 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
4440 // but rewrite each "in(i)" relative to the new "in(Bot)".
4441 Node *progress = NULL;
4442
4443
4444 Node* old_base = base_memory();
4445 Node* empty_mem = empty_memory();
4446 if (old_base == empty_mem)
4447 return NULL; // Dead memory path.
4448
4449 MergeMemNode* old_mbase;
4450 if (old_base != NULL && old_base->is_MergeMem())
4451 old_mbase = old_base->as_MergeMem();
4452 else
4453 old_mbase = NULL;
4454 Node* new_base = old_base;
4455
4456 // simplify stacked MergeMems in base memory
4457 if (old_mbase) new_base = old_mbase->base_memory();
4458
4459 // the base memory might contribute new slices beyond my req()
4460 if (old_mbase) grow_to_match(old_mbase);
4461
4462 // Look carefully at the base node if it is a phi.
4463 PhiNode* phi_base;
4464 if (new_base != NULL && new_base->is_Phi())
4465 phi_base = new_base->as_Phi();
4466 else
4467 phi_base = NULL;
4468
4469 Node* phi_reg = NULL;
4470 uint phi_len = (uint)-1;
4471 if (phi_base != NULL && !phi_base->is_copy()) {
4472 // do not examine phi if degraded to a copy
4473 phi_reg = phi_base->region();
4474 phi_len = phi_base->req();
4475 // see if the phi is unfinished
4476 for (uint i = 1; i < phi_len; i++) {
4477 if (phi_base->in(i) == NULL) {
4478 // incomplete phi; do not look at it yet!
4479 phi_reg = NULL;
4480 phi_len = (uint)-1;
4481 break;
4482 }
4483 }
4484 }
4485
4486 // Note: We do not call verify_sparse on entry, because inputs
4487 // can normalize to the base_memory via subsume_node or similar
4488 // mechanisms. This method repairs that damage.
4489
4490 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
4491
4492 // Look at each slice.
4493 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4494 Node* old_in = in(i);
4495 // calculate the old memory value
4496 Node* old_mem = old_in;
4497 if (old_mem == empty_mem) old_mem = old_base;
4498 assert(old_mem == memory_at(i), "");
4499
4500 // maybe update (reslice) the old memory value
4501
4502 // simplify stacked MergeMems
4503 Node* new_mem = old_mem;
4504 MergeMemNode* old_mmem;
4505 if (old_mem != NULL && old_mem->is_MergeMem())
4506 old_mmem = old_mem->as_MergeMem();
4507 else
4508 old_mmem = NULL;
4509 if (old_mmem == this) {
4510 // This can happen if loops break up and safepoints disappear.
4511 // A merge of BotPtr (default) with a RawPtr memory derived from a
4512 // safepoint can be rewritten to a merge of the same BotPtr with
4513 // the BotPtr phi coming into the loop. If that phi disappears
4514 // also, we can end up with a self-loop of the mergemem.
4515 // In general, if loops degenerate and memory effects disappear,
4516 // a mergemem can be left looking at itself. This simply means
4517 // that the mergemem's default should be used, since there is
4518 // no longer any apparent effect on this slice.
4519 // Note: If a memory slice is a MergeMem cycle, it is unreachable
4520 // from start. Update the input to TOP.
4521 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
4522 }
4523 else if (old_mmem != NULL) {
4524 new_mem = old_mmem->memory_at(i);
4525 }
4526 // else preceding memory was not a MergeMem
4527
4528 // replace equivalent phis (unfortunately, they do not GVN together)
4529 if (new_mem != NULL && new_mem != new_base &&
4530 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) {
4531 if (new_mem->is_Phi()) {
4532 PhiNode* phi_mem = new_mem->as_Phi();
4533 for (uint i = 1; i < phi_len; i++) {
4534 if (phi_base->in(i) != phi_mem->in(i)) {
4535 phi_mem = NULL;
4536 break;
4537 }
4538 }
4539 if (phi_mem != NULL) {
4540 // equivalent phi nodes; revert to the def
4541 new_mem = new_base;
4542 }
4543 }
4544 }
4545
4546 // maybe store down a new value
4547 Node* new_in = new_mem;
4548 if (new_in == new_base) new_in = empty_mem;
4549
4550 if (new_in != old_in) {
4551 // Warning: Do not combine this "if" with the previous "if"
4552 // A memory slice might have be be rewritten even if it is semantically
4553 // unchanged, if the base_memory value has changed.
4554 set_req(i, new_in);
4555 progress = this; // Report progress
4556 }
4557 }
4558
4559 if (new_base != old_base) {
4560 set_req(Compile::AliasIdxBot, new_base);
4561 // Don't use set_base_memory(new_base), because we need to update du.
4562 assert(base_memory() == new_base, "");
4563 progress = this;
4564 }
4565
4566 if( base_memory() == this ) {
4567 // a self cycle indicates this memory path is dead
4568 set_req(Compile::AliasIdxBot, empty_mem);
4569 }
4570
4571 // Resolve external cycles by calling Ideal on a MergeMem base_memory
4572 // Recursion must occur after the self cycle check above
4573 if( base_memory()->is_MergeMem() ) {
4574 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
4575 Node *m = phase->transform(new_mbase); // Rollup any cycles
4576 if( m != NULL &&
4577 (m->is_top() ||
4578 (m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem)) ) {
4579 // propagate rollup of dead cycle to self
4580 set_req(Compile::AliasIdxBot, empty_mem);
4581 }
4582 }
4583
4584 if( base_memory() == empty_mem ) {
4585 progress = this;
4586 // Cut inputs during Parse phase only.
4587 // During Optimize phase a dead MergeMem node will be subsumed by Top.
4588 if( !can_reshape ) {
4589 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4590 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
4591 }
4592 }
4593 }
4594
4595 if( !progress && base_memory()->is_Phi() && can_reshape ) {
4596 // Check if PhiNode::Ideal's "Split phis through memory merges"
4597 // transform should be attempted. Look for this->phi->this cycle.
4598 uint merge_width = req();
4599 if (merge_width > Compile::AliasIdxRaw) {
4600 PhiNode* phi = base_memory()->as_Phi();
4601 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
4602 if (phi->in(i) == this) {
4603 phase->is_IterGVN()->_worklist.push(phi);
4604 break;
4605 }
4606 }
4607 }
4608 }
4609
4610 assert(progress || verify_sparse(), "please, no dups of base");
4611 return progress;
4612 }
4613
4614 //-------------------------set_base_memory-------------------------------------
4615 void MergeMemNode::set_base_memory(Node *new_base) {
4616 Node* empty_mem = empty_memory();
4617 set_req(Compile::AliasIdxBot, new_base);
4618 assert(memory_at(req()) == new_base, "must set default memory");
4619 // Clear out other occurrences of new_base:
4620 if (new_base != empty_mem) {
4621 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4622 if (in(i) == new_base) set_req(i, empty_mem);
4623 }
4624 }
4625 }
4626
4627 //------------------------------out_RegMask------------------------------------
4628 const RegMask &MergeMemNode::out_RegMask() const {
4629 return RegMask::Empty;
4630 }
4631
4632 //------------------------------dump_spec--------------------------------------
4633 #ifndef PRODUCT
4634 void MergeMemNode::dump_spec(outputStream *st) const {
4635 st->print(" {");
4636 Node* base_mem = base_memory();
4637 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
4638 Node* mem = (in(i) != NULL) ? memory_at(i) : base_mem;
4639 if (mem == base_mem) { st->print(" -"); continue; }
4640 st->print( " N%d:", mem->_idx );
4641 Compile::current()->get_adr_type(i)->dump_on(st);
4642 }
4643 st->print(" }");
4644 }
4645 #endif // !PRODUCT
4646
4647
4648 #ifdef ASSERT
4649 static bool might_be_same(Node* a, Node* b) {
4650 if (a == b) return true;
4651 if (!(a->is_Phi() || b->is_Phi())) return false;
4652 // phis shift around during optimization
4653 return true; // pretty stupid...
4654 }
4655
4656 // verify a narrow slice (either incoming or outgoing)
4657 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
4658 if (!VerifyAliases) return; // don't bother to verify unless requested
4659 if (VMError::is_error_reported()) return; // muzzle asserts when debugging an error
4660 if (Node::in_dump()) return; // muzzle asserts when printing
4661 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
4662 assert(n != NULL, "");
4663 // Elide intervening MergeMem's
4664 while (n->is_MergeMem()) {
4665 n = n->as_MergeMem()->memory_at(alias_idx);
4666 }
4667 Compile* C = Compile::current();
4668 const TypePtr* n_adr_type = n->adr_type();
4669 if (n == m->empty_memory()) {
4670 // Implicit copy of base_memory()
4671 } else if (n_adr_type != TypePtr::BOTTOM) {
4672 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type");
4673 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
4674 } else {
4675 // A few places like make_runtime_call "know" that VM calls are narrow,
4676 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
4677 bool expected_wide_mem = false;
4678 if (n == m->base_memory()) {
4679 expected_wide_mem = true;
4680 } else if (alias_idx == Compile::AliasIdxRaw ||
4681 n == m->memory_at(Compile::AliasIdxRaw)) {
4682 expected_wide_mem = true;
4683 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
4684 // memory can "leak through" calls on channels that
4685 // are write-once. Allow this also.
4686 expected_wide_mem = true;
4687 }
4688 assert(expected_wide_mem, "expected narrow slice replacement");
4689 }
4690 }
4691 #else // !ASSERT
4692 #define verify_memory_slice(m,i,n) (void)(0) // PRODUCT version is no-op
4693 #endif
4694
4695
4696 //-----------------------------memory_at---------------------------------------
4697 Node* MergeMemNode::memory_at(uint alias_idx) const {
4698 assert(alias_idx >= Compile::AliasIdxRaw ||
4699 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0,
4700 "must avoid base_memory and AliasIdxTop");
4701
4702 // Otherwise, it is a narrow slice.
4703 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
4704 Compile *C = Compile::current();
4705 if (is_empty_memory(n)) {
4706 // the array is sparse; empty slots are the "top" node
4707 n = base_memory();
4708 assert(Node::in_dump()
4709 || n == NULL || n->bottom_type() == Type::TOP
4710 || n->adr_type() == NULL // address is TOP
4711 || n->adr_type() == TypePtr::BOTTOM
4712 || n->adr_type() == TypeRawPtr::BOTTOM
4713 || Compile::current()->AliasLevel() == 0,
4714 "must be a wide memory");
4715 // AliasLevel == 0 if we are organizing the memory states manually.
4716 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
4717 } else {
4718 // make sure the stored slice is sane
4719 #ifdef ASSERT
4720 if (VMError::is_error_reported() || Node::in_dump()) {
4721 } else if (might_be_same(n, base_memory())) {
4722 // Give it a pass: It is a mostly harmless repetition of the base.
4723 // This can arise normally from node subsumption during optimization.
4724 } else {
4725 verify_memory_slice(this, alias_idx, n);
4726 }
4727 #endif
4728 }
4729 return n;
4730 }
4731
4732 //---------------------------set_memory_at-------------------------------------
4733 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
4734 verify_memory_slice(this, alias_idx, n);
4735 Node* empty_mem = empty_memory();
4736 if (n == base_memory()) n = empty_mem; // collapse default
4737 uint need_req = alias_idx+1;
4738 if (req() < need_req) {
4739 if (n == empty_mem) return; // already the default, so do not grow me
4740 // grow the sparse array
4741 do {
4742 add_req(empty_mem);
4743 } while (req() < need_req);
4744 }
4745 set_req( alias_idx, n );
4746 }
4747
4748
4749
4750 //--------------------------iteration_setup------------------------------------
4751 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
4752 if (other != NULL) {
4753 grow_to_match(other);
4754 // invariant: the finite support of mm2 is within mm->req()
4755 #ifdef ASSERT
4756 for (uint i = req(); i < other->req(); i++) {
4757 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
4758 }
4759 #endif
4760 }
4761 // Replace spurious copies of base_memory by top.
4762 Node* base_mem = base_memory();
4763 if (base_mem != NULL && !base_mem->is_top()) {
4764 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
4765 if (in(i) == base_mem)
4766 set_req(i, empty_memory());
4767 }
4768 }
4769 }
4770
4771 //---------------------------grow_to_match-------------------------------------
4772 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
4773 Node* empty_mem = empty_memory();
4774 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
4775 // look for the finite support of the other memory
4776 for (uint i = other->req(); --i >= req(); ) {
4777 if (other->in(i) != empty_mem) {
4778 uint new_len = i+1;
4779 while (req() < new_len) add_req(empty_mem);
4780 break;
4781 }
4782 }
4783 }
4784
4785 //---------------------------verify_sparse-------------------------------------
4786 #ifndef PRODUCT
4787 bool MergeMemNode::verify_sparse() const {
4788 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
4789 Node* base_mem = base_memory();
4790 // The following can happen in degenerate cases, since empty==top.
4791 if (is_empty_memory(base_mem)) return true;
4792 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4793 assert(in(i) != NULL, "sane slice");
4794 if (in(i) == base_mem) return false; // should have been the sentinel value!
4795 }
4796 return true;
4797 }
4798
4799 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
4800 Node* n;
4801 n = mm->in(idx);
4802 if (mem == n) return true; // might be empty_memory()
4803 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
4804 if (mem == n) return true;
4805 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) {
4806 if (mem == n) return true;
4807 if (n == NULL) break;
4808 }
4809 return false;
4810 }
4811 #endif // !PRODUCT