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 "opto/rootnode.hpp"
48 #include "utilities/align.hpp"
49 #include "utilities/copy.hpp"
50 #include "utilities/macros.hpp"
51 #include "utilities/vmError.hpp"
52 #if INCLUDE_ZGC
53 #include "gc/z/c2/zBarrierSetC2.hpp"
54 #endif
55
56 // Portions of code courtesy of Clifford Click
57
58 // Optimization - Graph Style
59
60 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st);
61
62 //=============================================================================
63 uint MemNode::size_of() const { return sizeof(*this); }
64
65 const TypePtr *MemNode::adr_type() const {
66 Node* adr = in(Address);
67 if (adr == NULL) return NULL; // node is dead
68 const TypePtr* cross_check = NULL;
69 DEBUG_ONLY(cross_check = _adr_type);
70 return calculate_adr_type(adr->bottom_type(), cross_check);
71 }
72
73 bool MemNode::check_if_adr_maybe_raw(Node* adr) {
74 if (adr != NULL) {
75 if (adr->bottom_type()->base() == Type::RawPtr || adr->bottom_type()->base() == Type::AnyPtr) {
76 return true;
77 }
78 }
79 return false;
80 }
81
82 #ifndef PRODUCT
83 void MemNode::dump_spec(outputStream *st) const {
84 if (in(Address) == NULL) return; // node is dead
85 #ifndef ASSERT
86 // fake the missing field
87 const TypePtr* _adr_type = NULL;
88 if (in(Address) != NULL)
89 _adr_type = in(Address)->bottom_type()->isa_ptr();
90 #endif
91 dump_adr_type(this, _adr_type, st);
92
93 Compile* C = Compile::current();
94 if (C->alias_type(_adr_type)->is_volatile()) {
95 st->print(" Volatile!");
96 }
97 if (_unaligned_access) {
98 st->print(" unaligned");
99 }
100 if (_mismatched_access) {
101 st->print(" mismatched");
102 }
103 if (_unsafe_access) {
104 st->print(" unsafe");
105 }
106 }
107
108 void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) {
109 st->print(" @");
110 if (adr_type == NULL) {
111 st->print("NULL");
112 } else {
113 adr_type->dump_on(st);
114 Compile* C = Compile::current();
115 Compile::AliasType* atp = NULL;
116 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type);
117 if (atp == NULL)
118 st->print(", idx=?\?;");
119 else if (atp->index() == Compile::AliasIdxBot)
120 st->print(", idx=Bot;");
121 else if (atp->index() == Compile::AliasIdxTop)
122 st->print(", idx=Top;");
123 else if (atp->index() == Compile::AliasIdxRaw)
124 st->print(", idx=Raw;");
125 else {
126 ciField* field = atp->field();
127 if (field) {
128 st->print(", name=");
129 field->print_name_on(st);
130 }
131 st->print(", idx=%d;", atp->index());
132 }
133 }
134 }
135
136 extern void print_alias_types();
137
138 #endif
139
140 Node *MemNode::optimize_simple_memory_chain(Node *mchain, const TypeOopPtr *t_oop, Node *load, PhaseGVN *phase) {
141 assert((t_oop != NULL), "sanity");
142 bool is_instance = t_oop->is_known_instance_field();
143 bool is_boxed_value_load = t_oop->is_ptr_to_boxed_value() &&
144 (load != NULL) && load->is_Load() &&
145 (phase->is_IterGVN() != NULL);
146 if (!(is_instance || is_boxed_value_load))
147 return mchain; // don't try to optimize non-instance types
148 uint instance_id = t_oop->instance_id();
149 Node *start_mem = phase->C->start()->proj_out_or_null(TypeFunc::Memory);
150 Node *prev = NULL;
151 Node *result = mchain;
152 while (prev != result) {
153 prev = result;
154 if (result == start_mem)
155 break; // hit one of our sentinels
156 // skip over a call which does not affect this memory slice
157 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {
158 Node *proj_in = result->in(0);
159 if (proj_in->is_Allocate() && proj_in->_idx == instance_id) {
160 break; // hit one of our sentinels
161 } else if (proj_in->is_Call()) {
162 // ArrayCopyNodes processed here as well
163 CallNode *call = proj_in->as_Call();
164 if (!call->may_modify(t_oop, phase)) { // returns false for instances
165 result = call->in(TypeFunc::Memory);
166 }
167 } else if (proj_in->is_Initialize()) {
168 AllocateNode* alloc = proj_in->as_Initialize()->allocation();
169 // Stop if this is the initialization for the object instance which
170 // contains this memory slice, otherwise skip over it.
171 if ((alloc == NULL) || (alloc->_idx == instance_id)) {
172 break;
173 }
174 if (is_instance) {
175 result = proj_in->in(TypeFunc::Memory);
176 } else if (is_boxed_value_load) {
177 Node* klass = alloc->in(AllocateNode::KlassNode);
178 const TypeKlassPtr* tklass = phase->type(klass)->is_klassptr();
179 if (tklass->klass_is_exact() && !tklass->klass()->equals(t_oop->klass())) {
180 result = proj_in->in(TypeFunc::Memory); // not related allocation
181 }
182 }
183 } else if (proj_in->is_MemBar()) {
184 ArrayCopyNode* ac = NULL;
185 if (ArrayCopyNode::may_modify(t_oop, proj_in->as_MemBar(), phase, ac)) {
186 break;
187 }
188 result = proj_in->in(TypeFunc::Memory);
189 } else {
190 assert(false, "unexpected projection");
191 }
192 } else if (result->is_ClearArray()) {
193 if (!is_instance || !ClearArrayNode::step_through(&result, instance_id, phase)) {
194 // Can not bypass initialization of the instance
195 // we are looking for.
196 break;
197 }
198 // Otherwise skip it (the call updated 'result' value).
199 } else if (result->is_MergeMem()) {
200 result = step_through_mergemem(phase, result->as_MergeMem(), t_oop, NULL, tty);
201 }
202 }
203 return result;
204 }
205
206 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, Node *load, PhaseGVN *phase) {
207 const TypeOopPtr* t_oop = t_adr->isa_oopptr();
208 if (t_oop == NULL)
209 return mchain; // don't try to optimize non-oop types
210 Node* result = optimize_simple_memory_chain(mchain, t_oop, load, phase);
211 bool is_instance = t_oop->is_known_instance_field();
212 PhaseIterGVN *igvn = phase->is_IterGVN();
213 if (is_instance && igvn != NULL && result->is_Phi()) {
214 PhiNode *mphi = result->as_Phi();
215 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
216 const TypePtr *t = mphi->adr_type();
217 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
218 (t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
219 t->is_oopptr()->cast_to_exactness(true)
220 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
221 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop)) {
222 // clone the Phi with our address type
223 result = mphi->split_out_instance(t_adr, igvn);
224 } else {
225 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain");
226 }
227 }
228 return result;
229 }
230
231 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) {
232 uint alias_idx = phase->C->get_alias_index(tp);
233 Node *mem = mmem;
234 #ifdef ASSERT
235 {
236 // Check that current type is consistent with the alias index used during graph construction
237 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
238 bool consistent = adr_check == NULL || adr_check->empty() ||
239 phase->C->must_alias(adr_check, alias_idx );
240 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
241 if( !consistent && adr_check != NULL && !adr_check->empty() &&
242 tp->isa_aryptr() && tp->offset() == Type::OffsetBot &&
243 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot &&
244 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() ||
245 adr_check->offset() == oopDesc::klass_offset_in_bytes() ||
246 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) {
247 // don't assert if it is dead code.
248 consistent = true;
249 }
250 if( !consistent ) {
251 st->print("alias_idx==%d, adr_check==", alias_idx);
252 if( adr_check == NULL ) {
253 st->print("NULL");
254 } else {
255 adr_check->dump();
256 }
257 st->cr();
258 print_alias_types();
259 assert(consistent, "adr_check must match alias idx");
260 }
261 }
262 #endif
263 // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally
264 // means an array I have not precisely typed yet. Do not do any
265 // alias stuff with it any time soon.
266 const TypeOopPtr *toop = tp->isa_oopptr();
267 if( tp->base() != Type::AnyPtr &&
268 !(toop &&
269 toop->klass() != NULL &&
270 toop->klass()->is_java_lang_Object() &&
271 toop->offset() == Type::OffsetBot) ) {
272 // compress paths and change unreachable cycles to TOP
273 // If not, we can update the input infinitely along a MergeMem cycle
274 // Equivalent code in PhiNode::Ideal
275 Node* m = phase->transform(mmem);
276 // If transformed to a MergeMem, get the desired slice
277 // Otherwise the returned node represents memory for every slice
278 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
279 // Update input if it is progress over what we have now
280 }
281 return mem;
282 }
283
284 //--------------------------Ideal_common---------------------------------------
285 // Look for degenerate control and memory inputs. Bypass MergeMem inputs.
286 // Unhook non-raw memories from complete (macro-expanded) initializations.
287 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
288 // If our control input is a dead region, kill all below the region
289 Node *ctl = in(MemNode::Control);
290 if (ctl && remove_dead_region(phase, can_reshape))
291 return this;
292 ctl = in(MemNode::Control);
293 // Don't bother trying to transform a dead node
294 if (ctl && ctl->is_top()) return NodeSentinel;
295
296 PhaseIterGVN *igvn = phase->is_IterGVN();
297 // Wait if control on the worklist.
298 if (ctl && can_reshape && igvn != NULL) {
299 Node* bol = NULL;
300 Node* cmp = NULL;
301 if (ctl->in(0)->is_If()) {
302 assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity");
303 bol = ctl->in(0)->in(1);
304 if (bol->is_Bool())
305 cmp = ctl->in(0)->in(1)->in(1);
306 }
307 if (igvn->_worklist.member(ctl) ||
308 (bol != NULL && igvn->_worklist.member(bol)) ||
309 (cmp != NULL && igvn->_worklist.member(cmp)) ) {
310 // This control path may be dead.
311 // Delay this memory node transformation until the control is processed.
312 phase->is_IterGVN()->_worklist.push(this);
313 return NodeSentinel; // caller will return NULL
314 }
315 }
316 // Ignore if memory is dead, or self-loop
317 Node *mem = in(MemNode::Memory);
318 if (phase->type( mem ) == Type::TOP) return NodeSentinel; // caller will return NULL
319 assert(mem != this, "dead loop in MemNode::Ideal");
320
321 if (can_reshape && igvn != NULL && igvn->_worklist.member(mem)) {
322 // This memory slice may be dead.
323 // Delay this mem node transformation until the memory is processed.
324 phase->is_IterGVN()->_worklist.push(this);
325 return NodeSentinel; // caller will return NULL
326 }
327
328 Node *address = in(MemNode::Address);
329 const Type *t_adr = phase->type(address);
330 if (t_adr == Type::TOP) return NodeSentinel; // caller will return NULL
331
332 if (can_reshape && is_unsafe_access() && (t_adr == TypePtr::NULL_PTR)) {
333 // Unsafe off-heap access with zero address. Remove access and other control users
334 // to not confuse optimizations and add a HaltNode to fail if this is ever executed.
335 assert(ctl != NULL, "unsafe accesses should be control dependent");
336 for (DUIterator_Fast imax, i = ctl->fast_outs(imax); i < imax; i++) {
337 Node* u = ctl->fast_out(i);
338 if (u != ctl) {
339 igvn->rehash_node_delayed(u);
340 int nb = u->replace_edge(ctl, phase->C->top());
341 --i, imax -= nb;
342 }
343 }
344 Node* frame = igvn->transform(new ParmNode(phase->C->start(), TypeFunc::FramePtr));
345 Node* halt = igvn->transform(new HaltNode(ctl, frame));
346 phase->C->root()->add_req(halt);
347 return this;
348 }
349
350 if (can_reshape && igvn != NULL &&
351 (igvn->_worklist.member(address) ||
352 (igvn->_worklist.size() > 0 && t_adr != adr_type())) ) {
353 // The address's base and type may change when the address is processed.
354 // Delay this mem node transformation until the address is processed.
355 phase->is_IterGVN()->_worklist.push(this);
356 return NodeSentinel; // caller will return NULL
357 }
358
359 // Do NOT remove or optimize the next lines: ensure a new alias index
360 // is allocated for an oop pointer type before Escape Analysis.
361 // Note: C++ will not remove it since the call has side effect.
362 if (t_adr->isa_oopptr()) {
363 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr());
364 }
365
366 Node* base = NULL;
367 if (address->is_AddP()) {
368 base = address->in(AddPNode::Base);
369 }
370 if (base != NULL && phase->type(base)->higher_equal(TypePtr::NULL_PTR) &&
371 !t_adr->isa_rawptr()) {
372 // Note: raw address has TOP base and top->higher_equal(TypePtr::NULL_PTR) is true.
373 // Skip this node optimization if its address has TOP base.
374 return NodeSentinel; // caller will return NULL
375 }
376
377 // Avoid independent memory operations
378 Node* old_mem = mem;
379
380 // The code which unhooks non-raw memories from complete (macro-expanded)
381 // initializations was removed. After macro-expansion all stores catched
382 // by Initialize node became raw stores and there is no information
383 // which memory slices they modify. So it is unsafe to move any memory
384 // operation above these stores. Also in most cases hooked non-raw memories
385 // were already unhooked by using information from detect_ptr_independence()
386 // and find_previous_store().
387
388 if (mem->is_MergeMem()) {
389 MergeMemNode* mmem = mem->as_MergeMem();
390 const TypePtr *tp = t_adr->is_ptr();
391
392 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
393 }
394
395 if (mem != old_mem) {
396 set_req(MemNode::Memory, mem);
397 if (can_reshape && old_mem->outcnt() == 0 && igvn != NULL) {
398 igvn->_worklist.push(old_mem);
399 }
400 if (phase->type(mem) == Type::TOP) return NodeSentinel;
401 return this;
402 }
403
404 // let the subclass continue analyzing...
405 return NULL;
406 }
407
408 // Helper function for proving some simple control dominations.
409 // Attempt to prove that all control inputs of 'dom' dominate 'sub'.
410 // Already assumes that 'dom' is available at 'sub', and that 'sub'
411 // is not a constant (dominated by the method's StartNode).
412 // Used by MemNode::find_previous_store to prove that the
413 // control input of a memory operation predates (dominates)
414 // an allocation it wants to look past.
415 bool MemNode::all_controls_dominate(Node* dom, Node* sub) {
416 if (dom == NULL || dom->is_top() || sub == NULL || sub->is_top())
417 return false; // Conservative answer for dead code
418
419 // Check 'dom'. Skip Proj and CatchProj nodes.
420 dom = dom->find_exact_control(dom);
421 if (dom == NULL || dom->is_top())
422 return false; // Conservative answer for dead code
423
424 if (dom == sub) {
425 // For the case when, for example, 'sub' is Initialize and the original
426 // 'dom' is Proj node of the 'sub'.
427 return false;
428 }
429
430 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub)
431 return true;
432
433 // 'dom' dominates 'sub' if its control edge and control edges
434 // of all its inputs dominate or equal to sub's control edge.
435
436 // Currently 'sub' is either Allocate, Initialize or Start nodes.
437 // Or Region for the check in LoadNode::Ideal();
438 // 'sub' should have sub->in(0) != NULL.
439 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() ||
440 sub->is_Region() || sub->is_Call(), "expecting only these nodes");
441
442 // Get control edge of 'sub'.
443 Node* orig_sub = sub;
444 sub = sub->find_exact_control(sub->in(0));
445 if (sub == NULL || sub->is_top())
446 return false; // Conservative answer for dead code
447
448 assert(sub->is_CFG(), "expecting control");
449
450 if (sub == dom)
451 return true;
452
453 if (sub->is_Start() || sub->is_Root())
454 return false;
455
456 {
457 // Check all control edges of 'dom'.
458
459 ResourceMark rm;
460 Arena* arena = Thread::current()->resource_area();
461 Node_List nlist(arena);
462 Unique_Node_List dom_list(arena);
463
464 dom_list.push(dom);
465 bool only_dominating_controls = false;
466
467 for (uint next = 0; next < dom_list.size(); next++) {
468 Node* n = dom_list.at(next);
469 if (n == orig_sub)
470 return false; // One of dom's inputs dominated by sub.
471 if (!n->is_CFG() && n->pinned()) {
472 // Check only own control edge for pinned non-control nodes.
473 n = n->find_exact_control(n->in(0));
474 if (n == NULL || n->is_top())
475 return false; // Conservative answer for dead code
476 assert(n->is_CFG(), "expecting control");
477 dom_list.push(n);
478 } else if (n->is_Con() || n->is_Start() || n->is_Root()) {
479 only_dominating_controls = true;
480 } else if (n->is_CFG()) {
481 if (n->dominates(sub, nlist))
482 only_dominating_controls = true;
483 else
484 return false;
485 } else {
486 // First, own control edge.
487 Node* m = n->find_exact_control(n->in(0));
488 if (m != NULL) {
489 if (m->is_top())
490 return false; // Conservative answer for dead code
491 dom_list.push(m);
492 }
493 // Now, the rest of edges.
494 uint cnt = n->req();
495 for (uint i = 1; i < cnt; i++) {
496 m = n->find_exact_control(n->in(i));
497 if (m == NULL || m->is_top())
498 continue;
499 dom_list.push(m);
500 }
501 }
502 }
503 return only_dominating_controls;
504 }
505 }
506
507 //---------------------detect_ptr_independence---------------------------------
508 // Used by MemNode::find_previous_store to prove that two base
509 // pointers are never equal.
510 // The pointers are accompanied by their associated allocations,
511 // if any, which have been previously discovered by the caller.
512 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
513 Node* p2, AllocateNode* a2,
514 PhaseTransform* phase) {
515 // Attempt to prove that these two pointers cannot be aliased.
516 // They may both manifestly be allocations, and they should differ.
517 // Or, if they are not both allocations, they can be distinct constants.
518 // Otherwise, one is an allocation and the other a pre-existing value.
519 if (a1 == NULL && a2 == NULL) { // neither an allocation
520 return (p1 != p2) && p1->is_Con() && p2->is_Con();
521 } else if (a1 != NULL && a2 != NULL) { // both allocations
522 return (a1 != a2);
523 } else if (a1 != NULL) { // one allocation a1
524 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.)
525 return all_controls_dominate(p2, a1);
526 } else { //(a2 != NULL) // one allocation a2
527 return all_controls_dominate(p1, a2);
528 }
529 return false;
530 }
531
532
533 // Find an arraycopy that must have set (can_see_stored_value=true) or
534 // could have set (can_see_stored_value=false) the value for this load
535 Node* LoadNode::find_previous_arraycopy(PhaseTransform* phase, Node* ld_alloc, Node*& mem, bool can_see_stored_value) const {
536 if (mem->is_Proj() && mem->in(0) != NULL && (mem->in(0)->Opcode() == Op_MemBarStoreStore ||
537 mem->in(0)->Opcode() == Op_MemBarCPUOrder)) {
538 Node* mb = mem->in(0);
539 if (mb->in(0) != NULL && mb->in(0)->is_Proj() &&
540 mb->in(0)->in(0) != NULL && mb->in(0)->in(0)->is_ArrayCopy()) {
541 ArrayCopyNode* ac = mb->in(0)->in(0)->as_ArrayCopy();
542 if (ac->is_clonebasic()) {
543 intptr_t offset;
544 AllocateNode* alloc = AllocateNode::Ideal_allocation(ac->in(ArrayCopyNode::Dest), phase, offset);
545 if (alloc != NULL && alloc == ld_alloc) {
546 return ac;
547 }
548 }
549 }
550 } else if (mem->is_Proj() && mem->in(0) != NULL && mem->in(0)->is_ArrayCopy()) {
551 ArrayCopyNode* ac = mem->in(0)->as_ArrayCopy();
552
553 if (ac->is_arraycopy_validated() ||
554 ac->is_copyof_validated() ||
555 ac->is_copyofrange_validated()) {
556 Node* ld_addp = in(MemNode::Address);
557 if (ld_addp->is_AddP()) {
558 Node* ld_base = ld_addp->in(AddPNode::Address);
559 Node* ld_offs = ld_addp->in(AddPNode::Offset);
560
561 Node* dest = ac->in(ArrayCopyNode::Dest);
562
563 if (dest == ld_base) {
564 const TypeX *ld_offs_t = phase->type(ld_offs)->isa_intptr_t();
565 if (ac->modifies(ld_offs_t->_lo, ld_offs_t->_hi, phase, can_see_stored_value)) {
566 return ac;
567 }
568 if (!can_see_stored_value) {
569 mem = ac->in(TypeFunc::Memory);
570 }
571 }
572 }
573 }
574 }
575 return NULL;
576 }
577
578 // The logic for reordering loads and stores uses four steps:
579 // (a) Walk carefully past stores and initializations which we
580 // can prove are independent of this load.
581 // (b) Observe that the next memory state makes an exact match
582 // with self (load or store), and locate the relevant store.
583 // (c) Ensure that, if we were to wire self directly to the store,
584 // the optimizer would fold it up somehow.
585 // (d) Do the rewiring, and return, depending on some other part of
586 // the optimizer to fold up the load.
587 // This routine handles steps (a) and (b). Steps (c) and (d) are
588 // specific to loads and stores, so they are handled by the callers.
589 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.)
590 //
591 Node* MemNode::find_previous_store(PhaseTransform* phase) {
592 Node* ctrl = in(MemNode::Control);
593 Node* adr = in(MemNode::Address);
594 intptr_t offset = 0;
595 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
596 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase);
597
598 if (offset == Type::OffsetBot)
599 return NULL; // cannot unalias unless there are precise offsets
600
601 const bool adr_maybe_raw = check_if_adr_maybe_raw(adr);
602 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr();
603
604 intptr_t size_in_bytes = memory_size();
605
606 Node* mem = in(MemNode::Memory); // start searching here...
607
608 int cnt = 50; // Cycle limiter
609 for (;;) { // While we can dance past unrelated stores...
610 if (--cnt < 0) break; // Caught in cycle or a complicated dance?
611
612 Node* prev = mem;
613 if (mem->is_Store()) {
614 Node* st_adr = mem->in(MemNode::Address);
615 intptr_t st_offset = 0;
616 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
617 if (st_base == NULL)
618 break; // inscrutable pointer
619
620 // For raw accesses it's not enough to prove that constant offsets don't intersect.
621 // We need the bases to be the equal in order for the offset check to make sense.
622 if ((adr_maybe_raw || check_if_adr_maybe_raw(st_adr)) && st_base != base) {
623 break;
624 }
625
626 if (st_offset != offset && st_offset != Type::OffsetBot) {
627 const int MAX_STORE = BytesPerLong;
628 if (st_offset >= offset + size_in_bytes ||
629 st_offset <= offset - MAX_STORE ||
630 st_offset <= offset - mem->as_Store()->memory_size()) {
631 // Success: The offsets are provably independent.
632 // (You may ask, why not just test st_offset != offset and be done?
633 // The answer is that stores of different sizes can co-exist
634 // in the same sequence of RawMem effects. We sometimes initialize
635 // a whole 'tile' of array elements with a single jint or jlong.)
636 mem = mem->in(MemNode::Memory);
637 continue; // (a) advance through independent store memory
638 }
639 }
640 if (st_base != base &&
641 detect_ptr_independence(base, alloc,
642 st_base,
643 AllocateNode::Ideal_allocation(st_base, phase),
644 phase)) {
645 // Success: The bases are provably independent.
646 mem = mem->in(MemNode::Memory);
647 continue; // (a) advance through independent store memory
648 }
649
650 // (b) At this point, if the bases or offsets do not agree, we lose,
651 // since we have not managed to prove 'this' and 'mem' independent.
652 if (st_base == base && st_offset == offset) {
653 return mem; // let caller handle steps (c), (d)
654 }
655
656 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
657 InitializeNode* st_init = mem->in(0)->as_Initialize();
658 AllocateNode* st_alloc = st_init->allocation();
659 if (st_alloc == NULL)
660 break; // something degenerated
661 bool known_identical = false;
662 bool known_independent = false;
663 if (alloc == st_alloc)
664 known_identical = true;
665 else if (alloc != NULL)
666 known_independent = true;
667 else if (all_controls_dominate(this, st_alloc))
668 known_independent = true;
669
670 if (known_independent) {
671 // The bases are provably independent: Either they are
672 // manifestly distinct allocations, or else the control
673 // of this load dominates the store's allocation.
674 int alias_idx = phase->C->get_alias_index(adr_type());
675 if (alias_idx == Compile::AliasIdxRaw) {
676 mem = st_alloc->in(TypeFunc::Memory);
677 } else {
678 mem = st_init->memory(alias_idx);
679 }
680 continue; // (a) advance through independent store memory
681 }
682
683 // (b) at this point, if we are not looking at a store initializing
684 // the same allocation we are loading from, we lose.
685 if (known_identical) {
686 // From caller, can_see_stored_value will consult find_captured_store.
687 return mem; // let caller handle steps (c), (d)
688 }
689
690 } else if (find_previous_arraycopy(phase, alloc, mem, false) != NULL) {
691 if (prev != mem) {
692 // Found an arraycopy but it doesn't affect that load
693 continue;
694 }
695 // Found an arraycopy that may affect that load
696 return mem;
697 } else if (addr_t != NULL && addr_t->is_known_instance_field()) {
698 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
699 if (mem->is_Proj() && mem->in(0)->is_Call()) {
700 // ArrayCopyNodes processed here as well.
701 CallNode *call = mem->in(0)->as_Call();
702 if (!call->may_modify(addr_t, phase)) {
703 mem = call->in(TypeFunc::Memory);
704 continue; // (a) advance through independent call memory
705 }
706 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) {
707 ArrayCopyNode* ac = NULL;
708 if (ArrayCopyNode::may_modify(addr_t, mem->in(0)->as_MemBar(), phase, ac)) {
709 break;
710 }
711 mem = mem->in(0)->in(TypeFunc::Memory);
712 continue; // (a) advance through independent MemBar memory
713 } else if (mem->is_ClearArray()) {
714 if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) {
715 // (the call updated 'mem' value)
716 continue; // (a) advance through independent allocation memory
717 } else {
718 // Can not bypass initialization of the instance
719 // we are looking for.
720 return mem;
721 }
722 } else if (mem->is_MergeMem()) {
723 int alias_idx = phase->C->get_alias_index(adr_type());
724 mem = mem->as_MergeMem()->memory_at(alias_idx);
725 continue; // (a) advance through independent MergeMem memory
726 }
727 }
728
729 // Unless there is an explicit 'continue', we must bail out here,
730 // because 'mem' is an inscrutable memory state (e.g., a call).
731 break;
732 }
733
734 return NULL; // bail out
735 }
736
737 //----------------------calculate_adr_type-------------------------------------
738 // Helper function. Notices when the given type of address hits top or bottom.
739 // Also, asserts a cross-check of the type against the expected address type.
740 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
741 if (t == Type::TOP) return NULL; // does not touch memory any more?
742 #ifdef PRODUCT
743 cross_check = NULL;
744 #else
745 if (!VerifyAliases || VMError::is_error_reported() || Node::in_dump()) cross_check = NULL;
746 #endif
747 const TypePtr* tp = t->isa_ptr();
748 if (tp == NULL) {
749 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
750 return TypePtr::BOTTOM; // touches lots of memory
751 } else {
752 #ifdef ASSERT
753 // %%%% [phh] We don't check the alias index if cross_check is
754 // TypeRawPtr::BOTTOM. Needs to be investigated.
755 if (cross_check != NULL &&
756 cross_check != TypePtr::BOTTOM &&
757 cross_check != TypeRawPtr::BOTTOM) {
758 // Recheck the alias index, to see if it has changed (due to a bug).
759 Compile* C = Compile::current();
760 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
761 "must stay in the original alias category");
762 // The type of the address must be contained in the adr_type,
763 // disregarding "null"-ness.
764 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
765 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
766 assert(cross_check->meet(tp_notnull) == cross_check->remove_speculative(),
767 "real address must not escape from expected memory type");
768 }
769 #endif
770 return tp;
771 }
772 }
773
774 //=============================================================================
775 // Should LoadNode::Ideal() attempt to remove control edges?
776 bool LoadNode::can_remove_control() const {
777 return true;
778 }
779 uint LoadNode::size_of() const { return sizeof(*this); }
780 uint LoadNode::cmp( const Node &n ) const
781 { return !Type::cmp( _type, ((LoadNode&)n)._type ); }
782 const Type *LoadNode::bottom_type() const { return _type; }
783 uint LoadNode::ideal_reg() const {
784 return _type->ideal_reg();
785 }
786
787 #ifndef PRODUCT
788 void LoadNode::dump_spec(outputStream *st) const {
789 MemNode::dump_spec(st);
790 if( !Verbose && !WizardMode ) {
791 // standard dump does this in Verbose and WizardMode
792 st->print(" #"); _type->dump_on(st);
793 }
794 if (!depends_only_on_test()) {
795 st->print(" (does not depend only on test)");
796 }
797 }
798 #endif
799
800 #ifdef ASSERT
801 //----------------------------is_immutable_value-------------------------------
802 // Helper function to allow a raw load without control edge for some cases
803 bool LoadNode::is_immutable_value(Node* adr) {
804 return (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() &&
805 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal &&
806 (adr->in(AddPNode::Offset)->find_intptr_t_con(-1) ==
807 in_bytes(JavaThread::osthread_offset())));
808 }
809 #endif
810
811 //----------------------------LoadNode::make-----------------------------------
812 // Polymorphic factory method:
813 Node *LoadNode::make(PhaseGVN& gvn, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt, MemOrd mo,
814 ControlDependency control_dependency, bool unaligned, bool mismatched, bool unsafe) {
815 Compile* C = gvn.C;
816
817 // sanity check the alias category against the created node type
818 assert(!(adr_type->isa_oopptr() &&
819 adr_type->offset() == oopDesc::klass_offset_in_bytes()),
820 "use LoadKlassNode instead");
821 assert(!(adr_type->isa_aryptr() &&
822 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
823 "use LoadRangeNode instead");
824 // Check control edge of raw loads
825 assert( ctl != NULL || C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
826 // oop will be recorded in oop map if load crosses safepoint
827 rt->isa_oopptr() || is_immutable_value(adr),
828 "raw memory operations should have control edge");
829 LoadNode* load = NULL;
830 switch (bt) {
831 case T_BOOLEAN: load = new LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
832 case T_BYTE: load = new LoadBNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
833 case T_INT: load = new LoadINode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
834 case T_CHAR: load = new LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
835 case T_SHORT: load = new LoadSNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
836 case T_LONG: load = new LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency); break;
837 case T_FLOAT: load = new LoadFNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); break;
838 case T_DOUBLE: load = new LoadDNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); break;
839 case T_ADDRESS: load = new LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency); break;
840 case T_OBJECT:
841 #ifdef _LP64
842 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
843 load = new LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo, control_dependency);
844 } else
845 #endif
846 {
847 assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop");
848 load = new LoadPNode(ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency);
849 }
850 break;
851 default:
852 ShouldNotReachHere();
853 break;
854 }
855 assert(load != NULL, "LoadNode should have been created");
856 if (unaligned) {
857 load->set_unaligned_access();
858 }
859 if (mismatched) {
860 load->set_mismatched_access();
861 }
862 if (unsafe) {
863 load->set_unsafe_access();
864 }
865 if (load->Opcode() == Op_LoadN) {
866 Node* ld = gvn.transform(load);
867 return new DecodeNNode(ld, ld->bottom_type()->make_ptr());
868 }
869
870 return load;
871 }
872
873 LoadLNode* LoadLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo,
874 ControlDependency control_dependency, bool unaligned, bool mismatched, bool unsafe) {
875 bool require_atomic = true;
876 LoadLNode* load = new LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency, require_atomic);
877 if (unaligned) {
878 load->set_unaligned_access();
879 }
880 if (mismatched) {
881 load->set_mismatched_access();
882 }
883 if (unsafe) {
884 load->set_unsafe_access();
885 }
886 return load;
887 }
888
889 LoadDNode* LoadDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo,
890 ControlDependency control_dependency, bool unaligned, bool mismatched, bool unsafe) {
891 bool require_atomic = true;
892 LoadDNode* load = new LoadDNode(ctl, mem, adr, adr_type, rt, mo, control_dependency, require_atomic);
893 if (unaligned) {
894 load->set_unaligned_access();
895 }
896 if (mismatched) {
897 load->set_mismatched_access();
898 }
899 if (unsafe) {
900 load->set_unsafe_access();
901 }
902 return load;
903 }
904
905
906
907 //------------------------------hash-------------------------------------------
908 uint LoadNode::hash() const {
909 // unroll addition of interesting fields
910 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
911 }
912
913 static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) {
914 if ((atp != NULL) && (atp->index() >= Compile::AliasIdxRaw)) {
915 bool non_volatile = (atp->field() != NULL) && !atp->field()->is_volatile();
916 bool is_stable_ary = FoldStableValues &&
917 (tp != NULL) && (tp->isa_aryptr() != NULL) &&
918 tp->isa_aryptr()->is_stable();
919
920 return (eliminate_boxing && non_volatile) || is_stable_ary;
921 }
922
923 return false;
924 }
925
926 // Is the value loaded previously stored by an arraycopy? If so return
927 // a load node that reads from the source array so we may be able to
928 // optimize out the ArrayCopy node later.
929 Node* LoadNode::can_see_arraycopy_value(Node* st, PhaseGVN* phase) const {
930 #if INCLUDE_ZGC
931 if (UseZGC) {
932 if (bottom_type()->make_oopptr() != NULL) {
933 return NULL;
934 }
935 }
936 #endif
937
938 Node* ld_adr = in(MemNode::Address);
939 intptr_t ld_off = 0;
940 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
941 Node* ac = find_previous_arraycopy(phase, ld_alloc, st, true);
942 if (ac != NULL) {
943 assert(ac->is_ArrayCopy(), "what kind of node can this be?");
944
945 Node* mem = ac->in(TypeFunc::Memory);
946 Node* ctl = ac->in(0);
947 Node* src = ac->in(ArrayCopyNode::Src);
948
949 if (!ac->as_ArrayCopy()->is_clonebasic() && !phase->type(src)->isa_aryptr()) {
950 return NULL;
951 }
952
953 LoadNode* ld = clone()->as_Load();
954 Node* addp = in(MemNode::Address)->clone();
955 if (ac->as_ArrayCopy()->is_clonebasic()) {
956 assert(ld_alloc != NULL, "need an alloc");
957 assert(addp->is_AddP(), "address must be addp");
958 assert(addp->in(AddPNode::Base) == ac->in(ArrayCopyNode::Dest)->in(AddPNode::Base), "strange pattern");
959 assert(addp->in(AddPNode::Address) == ac->in(ArrayCopyNode::Dest)->in(AddPNode::Address), "strange pattern");
960 addp->set_req(AddPNode::Base, src->in(AddPNode::Base));
961 addp->set_req(AddPNode::Address, src->in(AddPNode::Address));
962 } else {
963 assert(ac->as_ArrayCopy()->is_arraycopy_validated() ||
964 ac->as_ArrayCopy()->is_copyof_validated() ||
965 ac->as_ArrayCopy()->is_copyofrange_validated(), "only supported cases");
966 assert(addp->in(AddPNode::Base) == addp->in(AddPNode::Address), "should be");
967 addp->set_req(AddPNode::Base, src);
968 addp->set_req(AddPNode::Address, src);
969
970 const TypeAryPtr* ary_t = phase->type(in(MemNode::Address))->isa_aryptr();
971 BasicType ary_elem = ary_t->klass()->as_array_klass()->element_type()->basic_type();
972 uint header = arrayOopDesc::base_offset_in_bytes(ary_elem);
973 uint shift = exact_log2(type2aelembytes(ary_elem));
974
975 Node* diff = phase->transform(new SubINode(ac->in(ArrayCopyNode::SrcPos), ac->in(ArrayCopyNode::DestPos)));
976 #ifdef _LP64
977 diff = phase->transform(new ConvI2LNode(diff));
978 #endif
979 diff = phase->transform(new LShiftXNode(diff, phase->intcon(shift)));
980
981 Node* offset = phase->transform(new AddXNode(addp->in(AddPNode::Offset), diff));
982 addp->set_req(AddPNode::Offset, offset);
983 }
984 addp = phase->transform(addp);
985 #ifdef ASSERT
986 const TypePtr* adr_type = phase->type(addp)->is_ptr();
987 ld->_adr_type = adr_type;
988 #endif
989 ld->set_req(MemNode::Address, addp);
990 ld->set_req(0, ctl);
991 ld->set_req(MemNode::Memory, mem);
992 // load depends on the tests that validate the arraycopy
993 ld->_control_dependency = Pinned;
994 return ld;
995 }
996 return NULL;
997 }
998
999
1000 //---------------------------can_see_stored_value------------------------------
1001 // This routine exists to make sure this set of tests is done the same
1002 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
1003 // will change the graph shape in a way which makes memory alive twice at the
1004 // same time (uses the Oracle model of aliasing), then some
1005 // LoadXNode::Identity will fold things back to the equivalence-class model
1006 // of aliasing.
1007 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const {
1008 Node* ld_adr = in(MemNode::Address);
1009 intptr_t ld_off = 0;
1010 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
1011 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
1012 Compile::AliasType* atp = (tp != NULL) ? phase->C->alias_type(tp) : NULL;
1013 // This is more general than load from boxing objects.
1014 if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) {
1015 uint alias_idx = atp->index();
1016 bool final = !atp->is_rewritable();
1017 Node* result = NULL;
1018 Node* current = st;
1019 // Skip through chains of MemBarNodes checking the MergeMems for
1020 // new states for the slice of this load. Stop once any other
1021 // kind of node is encountered. Loads from final memory can skip
1022 // through any kind of MemBar but normal loads shouldn't skip
1023 // through MemBarAcquire since the could allow them to move out of
1024 // a synchronized region.
1025 while (current->is_Proj()) {
1026 int opc = current->in(0)->Opcode();
1027 if ((final && (opc == Op_MemBarAcquire ||
1028 opc == Op_MemBarAcquireLock ||
1029 opc == Op_LoadFence)) ||
1030 opc == Op_MemBarRelease ||
1031 opc == Op_StoreFence ||
1032 opc == Op_MemBarReleaseLock ||
1033 opc == Op_MemBarStoreStore ||
1034 opc == Op_MemBarCPUOrder) {
1035 Node* mem = current->in(0)->in(TypeFunc::Memory);
1036 if (mem->is_MergeMem()) {
1037 MergeMemNode* merge = mem->as_MergeMem();
1038 Node* new_st = merge->memory_at(alias_idx);
1039 if (new_st == merge->base_memory()) {
1040 // Keep searching
1041 current = new_st;
1042 continue;
1043 }
1044 // Save the new memory state for the slice and fall through
1045 // to exit.
1046 result = new_st;
1047 }
1048 }
1049 break;
1050 }
1051 if (result != NULL) {
1052 st = result;
1053 }
1054 }
1055
1056 // Loop around twice in the case Load -> Initialize -> Store.
1057 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
1058 for (int trip = 0; trip <= 1; trip++) {
1059
1060 if (st->is_Store()) {
1061 Node* st_adr = st->in(MemNode::Address);
1062 if (!phase->eqv(st_adr, ld_adr)) {
1063 // Try harder before giving up... Match raw and non-raw pointers.
1064 intptr_t st_off = 0;
1065 AllocateNode* alloc = AllocateNode::Ideal_allocation(st_adr, phase, st_off);
1066 if (alloc == NULL) return NULL;
1067 if (alloc != ld_alloc) return NULL;
1068 if (ld_off != st_off) return NULL;
1069 // At this point we have proven something like this setup:
1070 // A = Allocate(...)
1071 // L = LoadQ(, AddP(CastPP(, A.Parm),, #Off))
1072 // S = StoreQ(, AddP(, A.Parm , #Off), V)
1073 // (Actually, we haven't yet proven the Q's are the same.)
1074 // In other words, we are loading from a casted version of
1075 // the same pointer-and-offset that we stored to.
1076 // Thus, we are able to replace L by V.
1077 }
1078 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
1079 if (store_Opcode() != st->Opcode())
1080 return NULL;
1081 return st->in(MemNode::ValueIn);
1082 }
1083
1084 // A load from a freshly-created object always returns zero.
1085 // (This can happen after LoadNode::Ideal resets the load's memory input
1086 // to find_captured_store, which returned InitializeNode::zero_memory.)
1087 if (st->is_Proj() && st->in(0)->is_Allocate() &&
1088 (st->in(0) == ld_alloc) &&
1089 (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) {
1090 // return a zero value for the load's basic type
1091 // (This is one of the few places where a generic PhaseTransform
1092 // can create new nodes. Think of it as lazily manifesting
1093 // virtually pre-existing constants.)
1094 return phase->zerocon(memory_type());
1095 }
1096
1097 // A load from an initialization barrier can match a captured store.
1098 if (st->is_Proj() && st->in(0)->is_Initialize()) {
1099 InitializeNode* init = st->in(0)->as_Initialize();
1100 AllocateNode* alloc = init->allocation();
1101 if ((alloc != NULL) && (alloc == ld_alloc)) {
1102 // examine a captured store value
1103 st = init->find_captured_store(ld_off, memory_size(), phase);
1104 if (st != NULL) {
1105 continue; // take one more trip around
1106 }
1107 }
1108 }
1109
1110 // Load boxed value from result of valueOf() call is input parameter.
1111 if (this->is_Load() && ld_adr->is_AddP() &&
1112 (tp != NULL) && tp->is_ptr_to_boxed_value()) {
1113 intptr_t ignore = 0;
1114 Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore);
1115 if (base != NULL && base->is_Proj() &&
1116 base->as_Proj()->_con == TypeFunc::Parms &&
1117 base->in(0)->is_CallStaticJava() &&
1118 base->in(0)->as_CallStaticJava()->is_boxing_method()) {
1119 return base->in(0)->in(TypeFunc::Parms);
1120 }
1121 }
1122
1123 break;
1124 }
1125
1126 return NULL;
1127 }
1128
1129 //----------------------is_instance_field_load_with_local_phi------------------
1130 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
1131 if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl &&
1132 in(Address)->is_AddP() ) {
1133 const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr();
1134 // Only instances and boxed values.
1135 if( t_oop != NULL &&
1136 (t_oop->is_ptr_to_boxed_value() ||
1137 t_oop->is_known_instance_field()) &&
1138 t_oop->offset() != Type::OffsetBot &&
1139 t_oop->offset() != Type::OffsetTop) {
1140 return true;
1141 }
1142 }
1143 return false;
1144 }
1145
1146 //------------------------------Identity---------------------------------------
1147 // Loads are identity if previous store is to same address
1148 Node* LoadNode::Identity(PhaseGVN* phase) {
1149 // If the previous store-maker is the right kind of Store, and the store is
1150 // to the same address, then we are equal to the value stored.
1151 Node* mem = in(Memory);
1152 Node* value = can_see_stored_value(mem, phase);
1153 if( value ) {
1154 // byte, short & char stores truncate naturally.
1155 // A load has to load the truncated value which requires
1156 // some sort of masking operation and that requires an
1157 // Ideal call instead of an Identity call.
1158 if (memory_size() < BytesPerInt) {
1159 // If the input to the store does not fit with the load's result type,
1160 // it must be truncated via an Ideal call.
1161 if (!phase->type(value)->higher_equal(phase->type(this)))
1162 return this;
1163 }
1164 // (This works even when value is a Con, but LoadNode::Value
1165 // usually runs first, producing the singleton type of the Con.)
1166 return value;
1167 }
1168
1169 // Search for an existing data phi which was generated before for the same
1170 // instance's field to avoid infinite generation of phis in a loop.
1171 Node *region = mem->in(0);
1172 if (is_instance_field_load_with_local_phi(region)) {
1173 const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr();
1174 int this_index = phase->C->get_alias_index(addr_t);
1175 int this_offset = addr_t->offset();
1176 int this_iid = addr_t->instance_id();
1177 if (!addr_t->is_known_instance() &&
1178 addr_t->is_ptr_to_boxed_value()) {
1179 // Use _idx of address base (could be Phi node) for boxed values.
1180 intptr_t ignore = 0;
1181 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1182 if (base == NULL) {
1183 return this;
1184 }
1185 this_iid = base->_idx;
1186 }
1187 const Type* this_type = bottom_type();
1188 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1189 Node* phi = region->fast_out(i);
1190 if (phi->is_Phi() && phi != mem &&
1191 phi->as_Phi()->is_same_inst_field(this_type, (int)mem->_idx, this_iid, this_index, this_offset)) {
1192 return phi;
1193 }
1194 }
1195 }
1196
1197 return this;
1198 }
1199
1200 // Construct an equivalent unsigned load.
1201 Node* LoadNode::convert_to_unsigned_load(PhaseGVN& gvn) {
1202 BasicType bt = T_ILLEGAL;
1203 const Type* rt = NULL;
1204 switch (Opcode()) {
1205 case Op_LoadUB: return this;
1206 case Op_LoadUS: return this;
1207 case Op_LoadB: bt = T_BOOLEAN; rt = TypeInt::UBYTE; break;
1208 case Op_LoadS: bt = T_CHAR; rt = TypeInt::CHAR; break;
1209 default:
1210 assert(false, "no unsigned variant: %s", Name());
1211 return NULL;
1212 }
1213 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1214 raw_adr_type(), rt, bt, _mo, _control_dependency,
1215 is_unaligned_access(), is_mismatched_access());
1216 }
1217
1218 // Construct an equivalent signed load.
1219 Node* LoadNode::convert_to_signed_load(PhaseGVN& gvn) {
1220 BasicType bt = T_ILLEGAL;
1221 const Type* rt = NULL;
1222 switch (Opcode()) {
1223 case Op_LoadUB: bt = T_BYTE; rt = TypeInt::BYTE; break;
1224 case Op_LoadUS: bt = T_SHORT; rt = TypeInt::SHORT; break;
1225 case Op_LoadB: // fall through
1226 case Op_LoadS: // fall through
1227 case Op_LoadI: // fall through
1228 case Op_LoadL: return this;
1229 default:
1230 assert(false, "no signed variant: %s", Name());
1231 return NULL;
1232 }
1233 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1234 raw_adr_type(), rt, bt, _mo, _control_dependency,
1235 is_unaligned_access(), is_mismatched_access());
1236 }
1237
1238 // We're loading from an object which has autobox behaviour.
1239 // If this object is result of a valueOf call we'll have a phi
1240 // merging a newly allocated object and a load from the cache.
1241 // We want to replace this load with the original incoming
1242 // argument to the valueOf call.
1243 Node* LoadNode::eliminate_autobox(PhaseGVN* phase) {
1244 assert(phase->C->eliminate_boxing(), "sanity");
1245 intptr_t ignore = 0;
1246 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1247 if ((base == NULL) || base->is_Phi()) {
1248 // Push the loads from the phi that comes from valueOf up
1249 // through it to allow elimination of the loads and the recovery
1250 // of the original value. It is done in split_through_phi().
1251 return NULL;
1252 } else if (base->is_Load() ||
1253 (base->is_DecodeN() && base->in(1)->is_Load())) {
1254 // Eliminate the load of boxed value for integer types from the cache
1255 // array by deriving the value from the index into the array.
1256 // Capture the offset of the load and then reverse the computation.
1257
1258 // Get LoadN node which loads a boxing object from 'cache' array.
1259 if (base->is_DecodeN()) {
1260 base = base->in(1);
1261 }
1262 if (!base->in(Address)->is_AddP()) {
1263 return NULL; // Complex address
1264 }
1265 AddPNode* address = base->in(Address)->as_AddP();
1266 Node* cache_base = address->in(AddPNode::Base);
1267 if ((cache_base != NULL) && cache_base->is_DecodeN()) {
1268 // Get ConP node which is static 'cache' field.
1269 cache_base = cache_base->in(1);
1270 }
1271 if ((cache_base != NULL) && cache_base->is_Con()) {
1272 const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr();
1273 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1274 Node* elements[4];
1275 int shift = exact_log2(type2aelembytes(T_OBJECT));
1276 int count = address->unpack_offsets(elements, ARRAY_SIZE(elements));
1277 if (count > 0 && elements[0]->is_Con() &&
1278 (count == 1 ||
1279 (count == 2 && elements[1]->Opcode() == Op_LShiftX &&
1280 elements[1]->in(2) == phase->intcon(shift)))) {
1281 ciObjArray* array = base_type->const_oop()->as_obj_array();
1282 // Fetch the box object cache[0] at the base of the array and get its value
1283 ciInstance* box = array->obj_at(0)->as_instance();
1284 ciInstanceKlass* ik = box->klass()->as_instance_klass();
1285 assert(ik->is_box_klass(), "sanity");
1286 assert(ik->nof_nonstatic_fields() == 1, "change following code");
1287 if (ik->nof_nonstatic_fields() == 1) {
1288 // This should be true nonstatic_field_at requires calling
1289 // nof_nonstatic_fields so check it anyway
1290 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1291 BasicType bt = c.basic_type();
1292 // Only integer types have boxing cache.
1293 assert(bt == T_BOOLEAN || bt == T_CHAR ||
1294 bt == T_BYTE || bt == T_SHORT ||
1295 bt == T_INT || bt == T_LONG, "wrong type = %s", type2name(bt));
1296 jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int();
1297 if (cache_low != (int)cache_low) {
1298 return NULL; // should not happen since cache is array indexed by value
1299 }
1300 jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift);
1301 if (offset != (int)offset) {
1302 return NULL; // should not happen since cache is array indexed by value
1303 }
1304 // Add up all the offsets making of the address of the load
1305 Node* result = elements[0];
1306 for (int i = 1; i < count; i++) {
1307 result = phase->transform(new AddXNode(result, elements[i]));
1308 }
1309 // Remove the constant offset from the address and then
1310 result = phase->transform(new AddXNode(result, phase->MakeConX(-(int)offset)));
1311 // remove the scaling of the offset to recover the original index.
1312 if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) {
1313 // Peel the shift off directly but wrap it in a dummy node
1314 // since Ideal can't return existing nodes
1315 result = new RShiftXNode(result->in(1), phase->intcon(0));
1316 } else if (result->is_Add() && result->in(2)->is_Con() &&
1317 result->in(1)->Opcode() == Op_LShiftX &&
1318 result->in(1)->in(2) == phase->intcon(shift)) {
1319 // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z)
1320 // but for boxing cache access we know that X<<Z will not overflow
1321 // (there is range check) so we do this optimizatrion by hand here.
1322 Node* add_con = new RShiftXNode(result->in(2), phase->intcon(shift));
1323 result = new AddXNode(result->in(1)->in(1), phase->transform(add_con));
1324 } else {
1325 result = new RShiftXNode(result, phase->intcon(shift));
1326 }
1327 #ifdef _LP64
1328 if (bt != T_LONG) {
1329 result = new ConvL2INode(phase->transform(result));
1330 }
1331 #else
1332 if (bt == T_LONG) {
1333 result = new ConvI2LNode(phase->transform(result));
1334 }
1335 #endif
1336 // Boxing/unboxing can be done from signed & unsigned loads (e.g. LoadUB -> ... -> LoadB pair).
1337 // Need to preserve unboxing load type if it is unsigned.
1338 switch(this->Opcode()) {
1339 case Op_LoadUB:
1340 result = new AndINode(phase->transform(result), phase->intcon(0xFF));
1341 break;
1342 case Op_LoadUS:
1343 result = new AndINode(phase->transform(result), phase->intcon(0xFFFF));
1344 break;
1345 }
1346 return result;
1347 }
1348 }
1349 }
1350 }
1351 }
1352 return NULL;
1353 }
1354
1355 static bool stable_phi(PhiNode* phi, PhaseGVN *phase) {
1356 Node* region = phi->in(0);
1357 if (region == NULL) {
1358 return false; // Wait stable graph
1359 }
1360 uint cnt = phi->req();
1361 for (uint i = 1; i < cnt; i++) {
1362 Node* rc = region->in(i);
1363 if (rc == NULL || phase->type(rc) == Type::TOP)
1364 return false; // Wait stable graph
1365 Node* in = phi->in(i);
1366 if (in == NULL || phase->type(in) == Type::TOP)
1367 return false; // Wait stable graph
1368 }
1369 return true;
1370 }
1371 //------------------------------split_through_phi------------------------------
1372 // Split instance or boxed field load through Phi.
1373 Node *LoadNode::split_through_phi(PhaseGVN *phase) {
1374 Node* mem = in(Memory);
1375 Node* address = in(Address);
1376 const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr();
1377
1378 assert((t_oop != NULL) &&
1379 (t_oop->is_known_instance_field() ||
1380 t_oop->is_ptr_to_boxed_value()), "invalide conditions");
1381
1382 Compile* C = phase->C;
1383 intptr_t ignore = 0;
1384 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1385 bool base_is_phi = (base != NULL) && base->is_Phi();
1386 bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() &&
1387 (base != NULL) && (base == address->in(AddPNode::Base)) &&
1388 phase->type(base)->higher_equal(TypePtr::NOTNULL);
1389
1390 if (!((mem->is_Phi() || base_is_phi) &&
1391 (load_boxed_values || t_oop->is_known_instance_field()))) {
1392 return NULL; // memory is not Phi
1393 }
1394
1395 if (mem->is_Phi()) {
1396 if (!stable_phi(mem->as_Phi(), phase)) {
1397 return NULL; // Wait stable graph
1398 }
1399 uint cnt = mem->req();
1400 // Check for loop invariant memory.
1401 if (cnt == 3) {
1402 for (uint i = 1; i < cnt; i++) {
1403 Node* in = mem->in(i);
1404 Node* m = optimize_memory_chain(in, t_oop, this, phase);
1405 if (m == mem) {
1406 if (i == 1) {
1407 // if the first edge was a loop, check second edge too.
1408 // If both are replaceable - we are in an infinite loop
1409 Node *n = optimize_memory_chain(mem->in(2), t_oop, this, phase);
1410 if (n == mem) {
1411 break;
1412 }
1413 }
1414 set_req(Memory, mem->in(cnt - i));
1415 return this; // made change
1416 }
1417 }
1418 }
1419 }
1420 if (base_is_phi) {
1421 if (!stable_phi(base->as_Phi(), phase)) {
1422 return NULL; // Wait stable graph
1423 }
1424 uint cnt = base->req();
1425 // Check for loop invariant memory.
1426 if (cnt == 3) {
1427 for (uint i = 1; i < cnt; i++) {
1428 if (base->in(i) == base) {
1429 return NULL; // Wait stable graph
1430 }
1431 }
1432 }
1433 }
1434
1435 bool load_boxed_phi = load_boxed_values && base_is_phi && (base->in(0) == mem->in(0));
1436
1437 // Split through Phi (see original code in loopopts.cpp).
1438 assert(C->have_alias_type(t_oop), "instance should have alias type");
1439
1440 // Do nothing here if Identity will find a value
1441 // (to avoid infinite chain of value phis generation).
1442 if (!phase->eqv(this, phase->apply_identity(this)))
1443 return NULL;
1444
1445 // Select Region to split through.
1446 Node* region;
1447 if (!base_is_phi) {
1448 assert(mem->is_Phi(), "sanity");
1449 region = mem->in(0);
1450 // Skip if the region dominates some control edge of the address.
1451 if (!MemNode::all_controls_dominate(address, region))
1452 return NULL;
1453 } else if (!mem->is_Phi()) {
1454 assert(base_is_phi, "sanity");
1455 region = base->in(0);
1456 // Skip if the region dominates some control edge of the memory.
1457 if (!MemNode::all_controls_dominate(mem, region))
1458 return NULL;
1459 } else if (base->in(0) != mem->in(0)) {
1460 assert(base_is_phi && mem->is_Phi(), "sanity");
1461 if (MemNode::all_controls_dominate(mem, base->in(0))) {
1462 region = base->in(0);
1463 } else if (MemNode::all_controls_dominate(address, mem->in(0))) {
1464 region = mem->in(0);
1465 } else {
1466 return NULL; // complex graph
1467 }
1468 } else {
1469 assert(base->in(0) == mem->in(0), "sanity");
1470 region = mem->in(0);
1471 }
1472
1473 const Type* this_type = this->bottom_type();
1474 int this_index = C->get_alias_index(t_oop);
1475 int this_offset = t_oop->offset();
1476 int this_iid = t_oop->instance_id();
1477 if (!t_oop->is_known_instance() && load_boxed_values) {
1478 // Use _idx of address base for boxed values.
1479 this_iid = base->_idx;
1480 }
1481 PhaseIterGVN* igvn = phase->is_IterGVN();
1482 Node* phi = new PhiNode(region, this_type, NULL, mem->_idx, this_iid, this_index, this_offset);
1483 for (uint i = 1; i < region->req(); i++) {
1484 Node* x;
1485 Node* the_clone = NULL;
1486 if (region->in(i) == C->top()) {
1487 x = C->top(); // Dead path? Use a dead data op
1488 } else {
1489 x = this->clone(); // Else clone up the data op
1490 the_clone = x; // Remember for possible deletion.
1491 // Alter data node to use pre-phi inputs
1492 if (this->in(0) == region) {
1493 x->set_req(0, region->in(i));
1494 } else {
1495 x->set_req(0, NULL);
1496 }
1497 if (mem->is_Phi() && (mem->in(0) == region)) {
1498 x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone.
1499 }
1500 if (address->is_Phi() && address->in(0) == region) {
1501 x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone
1502 }
1503 if (base_is_phi && (base->in(0) == region)) {
1504 Node* base_x = base->in(i); // Clone address for loads from boxed objects.
1505 Node* adr_x = phase->transform(new AddPNode(base_x,base_x,address->in(AddPNode::Offset)));
1506 x->set_req(Address, adr_x);
1507 }
1508 }
1509 // Check for a 'win' on some paths
1510 const Type *t = x->Value(igvn);
1511
1512 bool singleton = t->singleton();
1513
1514 // See comments in PhaseIdealLoop::split_thru_phi().
1515 if (singleton && t == Type::TOP) {
1516 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1517 }
1518
1519 if (singleton) {
1520 x = igvn->makecon(t);
1521 } else {
1522 // We now call Identity to try to simplify the cloned node.
1523 // Note that some Identity methods call phase->type(this).
1524 // Make sure that the type array is big enough for
1525 // our new node, even though we may throw the node away.
1526 // (This tweaking with igvn only works because x is a new node.)
1527 igvn->set_type(x, t);
1528 // If x is a TypeNode, capture any more-precise type permanently into Node
1529 // otherwise it will be not updated during igvn->transform since
1530 // igvn->type(x) is set to x->Value() already.
1531 x->raise_bottom_type(t);
1532 Node *y = igvn->apply_identity(x);
1533 if (y != x) {
1534 x = y;
1535 } else {
1536 y = igvn->hash_find_insert(x);
1537 if (y) {
1538 x = y;
1539 } else {
1540 // Else x is a new node we are keeping
1541 // We do not need register_new_node_with_optimizer
1542 // because set_type has already been called.
1543 igvn->_worklist.push(x);
1544 }
1545 }
1546 }
1547 if (x != the_clone && the_clone != NULL) {
1548 igvn->remove_dead_node(the_clone);
1549 }
1550 phi->set_req(i, x);
1551 }
1552 // Record Phi
1553 igvn->register_new_node_with_optimizer(phi);
1554 return phi;
1555 }
1556
1557 //------------------------------Ideal------------------------------------------
1558 // If the load is from Field memory and the pointer is non-null, it might be possible to
1559 // zero out the control input.
1560 // If the offset is constant and the base is an object allocation,
1561 // try to hook me up to the exact initializing store.
1562 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1563 Node* p = MemNode::Ideal_common(phase, can_reshape);
1564 if (p) return (p == NodeSentinel) ? NULL : p;
1565
1566 Node* ctrl = in(MemNode::Control);
1567 Node* address = in(MemNode::Address);
1568 bool progress = false;
1569
1570 bool addr_mark = ((phase->type(address)->isa_oopptr() || phase->type(address)->isa_narrowoop()) &&
1571 phase->type(address)->is_ptr()->offset() == oopDesc::mark_offset_in_bytes());
1572
1573 // Skip up past a SafePoint control. Cannot do this for Stores because
1574 // pointer stores & cardmarks must stay on the same side of a SafePoint.
1575 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint &&
1576 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw &&
1577 !addr_mark ) {
1578 ctrl = ctrl->in(0);
1579 set_req(MemNode::Control,ctrl);
1580 progress = true;
1581 }
1582
1583 intptr_t ignore = 0;
1584 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1585 if (base != NULL
1586 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
1587 // Check for useless control edge in some common special cases
1588 if (in(MemNode::Control) != NULL
1589 && can_remove_control()
1590 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1591 && all_controls_dominate(base, phase->C->start())) {
1592 // A method-invariant, non-null address (constant or 'this' argument).
1593 set_req(MemNode::Control, NULL);
1594 progress = true;
1595 }
1596 }
1597
1598 Node* mem = in(MemNode::Memory);
1599 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1600
1601 if (can_reshape && (addr_t != NULL)) {
1602 // try to optimize our memory input
1603 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase);
1604 if (opt_mem != mem) {
1605 set_req(MemNode::Memory, opt_mem);
1606 if (phase->type( opt_mem ) == Type::TOP) return NULL;
1607 return this;
1608 }
1609 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1610 if ((t_oop != NULL) &&
1611 (t_oop->is_known_instance_field() ||
1612 t_oop->is_ptr_to_boxed_value())) {
1613 PhaseIterGVN *igvn = phase->is_IterGVN();
1614 if (igvn != NULL && igvn->_worklist.member(opt_mem)) {
1615 // Delay this transformation until memory Phi is processed.
1616 phase->is_IterGVN()->_worklist.push(this);
1617 return NULL;
1618 }
1619 // Split instance field load through Phi.
1620 Node* result = split_through_phi(phase);
1621 if (result != NULL) return result;
1622
1623 if (t_oop->is_ptr_to_boxed_value()) {
1624 Node* result = eliminate_autobox(phase);
1625 if (result != NULL) return result;
1626 }
1627 }
1628 }
1629
1630 // Is there a dominating load that loads the same value? Leave
1631 // anything that is not a load of a field/array element (like
1632 // barriers etc.) alone
1633 if (in(0) != NULL && !adr_type()->isa_rawptr() && can_reshape) {
1634 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) {
1635 Node *use = mem->fast_out(i);
1636 if (use != this &&
1637 use->Opcode() == Opcode() &&
1638 use->in(0) != NULL &&
1639 use->in(0) != in(0) &&
1640 use->in(Address) == in(Address)) {
1641 Node* ctl = in(0);
1642 for (int i = 0; i < 10 && ctl != NULL; i++) {
1643 ctl = IfNode::up_one_dom(ctl);
1644 if (ctl == use->in(0)) {
1645 set_req(0, use->in(0));
1646 return this;
1647 }
1648 }
1649 }
1650 }
1651 }
1652
1653 // Check for prior store with a different base or offset; make Load
1654 // independent. Skip through any number of them. Bail out if the stores
1655 // are in an endless dead cycle and report no progress. This is a key
1656 // transform for Reflection. However, if after skipping through the Stores
1657 // we can't then fold up against a prior store do NOT do the transform as
1658 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
1659 // array memory alive twice: once for the hoisted Load and again after the
1660 // bypassed Store. This situation only works if EVERYBODY who does
1661 // anti-dependence work knows how to bypass. I.e. we need all
1662 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
1663 // the alias index stuff. So instead, peek through Stores and IFF we can
1664 // fold up, do so.
1665 Node* prev_mem = find_previous_store(phase);
1666 if (prev_mem != NULL) {
1667 Node* value = can_see_arraycopy_value(prev_mem, phase);
1668 if (value != NULL) {
1669 return value;
1670 }
1671 }
1672 // Steps (a), (b): Walk past independent stores to find an exact match.
1673 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) {
1674 // (c) See if we can fold up on the spot, but don't fold up here.
1675 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
1676 // just return a prior value, which is done by Identity calls.
1677 if (can_see_stored_value(prev_mem, phase)) {
1678 // Make ready for step (d):
1679 set_req(MemNode::Memory, prev_mem);
1680 return this;
1681 }
1682 }
1683
1684 return progress ? this : NULL;
1685 }
1686
1687 // Helper to recognize certain Klass fields which are invariant across
1688 // some group of array types (e.g., int[] or all T[] where T < Object).
1689 const Type*
1690 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1691 ciKlass* klass) const {
1692 if (tkls->offset() == in_bytes(Klass::modifier_flags_offset())) {
1693 // The field is Klass::_modifier_flags. Return its (constant) value.
1694 // (Folds up the 2nd indirection in aClassConstant.getModifiers().)
1695 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags");
1696 return TypeInt::make(klass->modifier_flags());
1697 }
1698 if (tkls->offset() == in_bytes(Klass::access_flags_offset())) {
1699 // The field is Klass::_access_flags. Return its (constant) value.
1700 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1701 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags");
1702 return TypeInt::make(klass->access_flags());
1703 }
1704 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) {
1705 // The field is Klass::_layout_helper. Return its constant value if known.
1706 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper");
1707 return TypeInt::make(klass->layout_helper());
1708 }
1709
1710 // No match.
1711 return NULL;
1712 }
1713
1714 //------------------------------Value-----------------------------------------
1715 const Type* LoadNode::Value(PhaseGVN* phase) const {
1716 // Either input is TOP ==> the result is TOP
1717 Node* mem = in(MemNode::Memory);
1718 const Type *t1 = phase->type(mem);
1719 if (t1 == Type::TOP) return Type::TOP;
1720 Node* adr = in(MemNode::Address);
1721 const TypePtr* tp = phase->type(adr)->isa_ptr();
1722 if (tp == NULL || tp->empty()) return Type::TOP;
1723 int off = tp->offset();
1724 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
1725 Compile* C = phase->C;
1726
1727 // Try to guess loaded type from pointer type
1728 if (tp->isa_aryptr()) {
1729 const TypeAryPtr* ary = tp->is_aryptr();
1730 const Type* t = ary->elem();
1731
1732 // Determine whether the reference is beyond the header or not, by comparing
1733 // the offset against the offset of the start of the array's data.
1734 // Different array types begin at slightly different offsets (12 vs. 16).
1735 // We choose T_BYTE as an example base type that is least restrictive
1736 // as to alignment, which will therefore produce the smallest
1737 // possible base offset.
1738 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
1739 const bool off_beyond_header = ((uint)off >= (uint)min_base_off);
1740
1741 // Try to constant-fold a stable array element.
1742 if (FoldStableValues && !is_mismatched_access() && ary->is_stable()) {
1743 // Make sure the reference is not into the header and the offset is constant
1744 ciObject* aobj = ary->const_oop();
1745 if (aobj != NULL && off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) {
1746 int stable_dimension = (ary->stable_dimension() > 0 ? ary->stable_dimension() - 1 : 0);
1747 const Type* con_type = Type::make_constant_from_array_element(aobj->as_array(), off,
1748 stable_dimension,
1749 memory_type(), is_unsigned());
1750 if (con_type != NULL) {
1751 return con_type;
1752 }
1753 }
1754 }
1755
1756 // Don't do this for integer types. There is only potential profit if
1757 // the element type t is lower than _type; that is, for int types, if _type is
1758 // more restrictive than t. This only happens here if one is short and the other
1759 // char (both 16 bits), and in those cases we've made an intentional decision
1760 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
1761 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
1762 //
1763 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
1764 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
1765 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
1766 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
1767 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
1768 // In fact, that could have been the original type of p1, and p1 could have
1769 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
1770 // expression (LShiftL quux 3) independently optimized to the constant 8.
1771 if ((t->isa_int() == NULL) && (t->isa_long() == NULL)
1772 && (_type->isa_vect() == NULL)
1773 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
1774 // t might actually be lower than _type, if _type is a unique
1775 // concrete subclass of abstract class t.
1776 if (off_beyond_header) { // is the offset beyond the header?
1777 const Type* jt = t->join_speculative(_type);
1778 // In any case, do not allow the join, per se, to empty out the type.
1779 if (jt->empty() && !t->empty()) {
1780 // This can happen if a interface-typed array narrows to a class type.
1781 jt = _type;
1782 }
1783 #ifdef ASSERT
1784 if (phase->C->eliminate_boxing() && adr->is_AddP()) {
1785 // The pointers in the autobox arrays are always non-null
1786 Node* base = adr->in(AddPNode::Base);
1787 if ((base != NULL) && base->is_DecodeN()) {
1788 // Get LoadN node which loads IntegerCache.cache field
1789 base = base->in(1);
1790 }
1791 if ((base != NULL) && base->is_Con()) {
1792 const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr();
1793 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1794 // It could be narrow oop
1795 assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity");
1796 }
1797 }
1798 }
1799 #endif
1800 return jt;
1801 }
1802 }
1803 } else if (tp->base() == Type::InstPtr) {
1804 assert( off != Type::OffsetBot ||
1805 // arrays can be cast to Objects
1806 tp->is_oopptr()->klass()->is_java_lang_Object() ||
1807 // unsafe field access may not have a constant offset
1808 C->has_unsafe_access(),
1809 "Field accesses must be precise" );
1810 // For oop loads, we expect the _type to be precise.
1811
1812 // Optimize loads from constant fields.
1813 const TypeInstPtr* tinst = tp->is_instptr();
1814 ciObject* const_oop = tinst->const_oop();
1815 if (!is_mismatched_access() && off != Type::OffsetBot && const_oop != NULL && const_oop->is_instance()) {
1816 const Type* con_type = Type::make_constant_from_field(const_oop->as_instance(), off, is_unsigned(), memory_type());
1817 if (con_type != NULL) {
1818 return con_type;
1819 }
1820 }
1821 } else if (tp->base() == Type::KlassPtr) {
1822 assert( off != Type::OffsetBot ||
1823 // arrays can be cast to Objects
1824 tp->is_klassptr()->klass()->is_java_lang_Object() ||
1825 // also allow array-loading from the primary supertype
1826 // array during subtype checks
1827 Opcode() == Op_LoadKlass,
1828 "Field accesses must be precise" );
1829 // For klass/static loads, we expect the _type to be precise
1830 } else if (tp->base() == Type::RawPtr && adr->is_Load() && off == 0) {
1831 /* With mirrors being an indirect in the Klass*
1832 * the VM is now using two loads. LoadKlass(LoadP(LoadP(Klass, mirror_offset), zero_offset))
1833 * The LoadP from the Klass has a RawPtr type (see LibraryCallKit::load_mirror_from_klass).
1834 *
1835 * So check the type and klass of the node before the LoadP.
1836 */
1837 Node* adr2 = adr->in(MemNode::Address);
1838 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
1839 if (tkls != NULL && !StressReflectiveCode) {
1840 ciKlass* klass = tkls->klass();
1841 if (klass->is_loaded() && tkls->klass_is_exact() && tkls->offset() == in_bytes(Klass::java_mirror_offset())) {
1842 assert(adr->Opcode() == Op_LoadP, "must load an oop from _java_mirror");
1843 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
1844 return TypeInstPtr::make(klass->java_mirror());
1845 }
1846 }
1847 }
1848
1849 const TypeKlassPtr *tkls = tp->isa_klassptr();
1850 if (tkls != NULL && !StressReflectiveCode) {
1851 ciKlass* klass = tkls->klass();
1852 if (klass->is_loaded() && tkls->klass_is_exact()) {
1853 // We are loading a field from a Klass metaobject whose identity
1854 // is known at compile time (the type is "exact" or "precise").
1855 // Check for fields we know are maintained as constants by the VM.
1856 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) {
1857 // The field is Klass::_super_check_offset. Return its (constant) value.
1858 // (Folds up type checking code.)
1859 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
1860 return TypeInt::make(klass->super_check_offset());
1861 }
1862 // Compute index into primary_supers array
1863 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1864 // Check for overflowing; use unsigned compare to handle the negative case.
1865 if( depth < ciKlass::primary_super_limit() ) {
1866 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1867 // (Folds up type checking code.)
1868 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1869 ciKlass *ss = klass->super_of_depth(depth);
1870 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1871 }
1872 const Type* aift = load_array_final_field(tkls, klass);
1873 if (aift != NULL) return aift;
1874 }
1875
1876 // We can still check if we are loading from the primary_supers array at a
1877 // shallow enough depth. Even though the klass is not exact, entries less
1878 // than or equal to its super depth are correct.
1879 if (klass->is_loaded() ) {
1880 ciType *inner = klass;
1881 while( inner->is_obj_array_klass() )
1882 inner = inner->as_obj_array_klass()->base_element_type();
1883 if( inner->is_instance_klass() &&
1884 !inner->as_instance_klass()->flags().is_interface() ) {
1885 // Compute index into primary_supers array
1886 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1887 // Check for overflowing; use unsigned compare to handle the negative case.
1888 if( depth < ciKlass::primary_super_limit() &&
1889 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case
1890 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1891 // (Folds up type checking code.)
1892 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1893 ciKlass *ss = klass->super_of_depth(depth);
1894 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1895 }
1896 }
1897 }
1898
1899 // If the type is enough to determine that the thing is not an array,
1900 // we can give the layout_helper a positive interval type.
1901 // This will help short-circuit some reflective code.
1902 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())
1903 && !klass->is_array_klass() // not directly typed as an array
1904 && !klass->is_interface() // specifically not Serializable & Cloneable
1905 && !klass->is_java_lang_Object() // not the supertype of all T[]
1906 ) {
1907 // Note: When interfaces are reliable, we can narrow the interface
1908 // test to (klass != Serializable && klass != Cloneable).
1909 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
1910 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
1911 // The key property of this type is that it folds up tests
1912 // for array-ness, since it proves that the layout_helper is positive.
1913 // Thus, a generic value like the basic object layout helper works fine.
1914 return TypeInt::make(min_size, max_jint, Type::WidenMin);
1915 }
1916 }
1917
1918 // If we are loading from a freshly-allocated object, produce a zero,
1919 // if the load is provably beyond the header of the object.
1920 // (Also allow a variable load from a fresh array to produce zero.)
1921 const TypeOopPtr *tinst = tp->isa_oopptr();
1922 bool is_instance = (tinst != NULL) && tinst->is_known_instance_field();
1923 bool is_boxed_value = (tinst != NULL) && tinst->is_ptr_to_boxed_value();
1924 if (ReduceFieldZeroing || is_instance || is_boxed_value) {
1925 Node* value = can_see_stored_value(mem,phase);
1926 if (value != NULL && value->is_Con()) {
1927 assert(value->bottom_type()->higher_equal(_type),"sanity");
1928 return value->bottom_type();
1929 }
1930 }
1931
1932 if (is_instance) {
1933 // If we have an instance type and our memory input is the
1934 // programs's initial memory state, there is no matching store,
1935 // so just return a zero of the appropriate type
1936 Node *mem = in(MemNode::Memory);
1937 if (mem->is_Parm() && mem->in(0)->is_Start()) {
1938 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
1939 return Type::get_zero_type(_type->basic_type());
1940 }
1941 }
1942 return _type;
1943 }
1944
1945 //------------------------------match_edge-------------------------------------
1946 // Do we Match on this edge index or not? Match only the address.
1947 uint LoadNode::match_edge(uint idx) const {
1948 return idx == MemNode::Address;
1949 }
1950
1951 //--------------------------LoadBNode::Ideal--------------------------------------
1952 //
1953 // If the previous store is to the same address as this load,
1954 // and the value stored was larger than a byte, replace this load
1955 // with the value stored truncated to a byte. If no truncation is
1956 // needed, the replacement is done in LoadNode::Identity().
1957 //
1958 Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1959 Node* mem = in(MemNode::Memory);
1960 Node* value = can_see_stored_value(mem,phase);
1961 if( value && !phase->type(value)->higher_equal( _type ) ) {
1962 Node *result = phase->transform( new LShiftINode(value, phase->intcon(24)) );
1963 return new RShiftINode(result, phase->intcon(24));
1964 }
1965 // Identity call will handle the case where truncation is not needed.
1966 return LoadNode::Ideal(phase, can_reshape);
1967 }
1968
1969 const Type* LoadBNode::Value(PhaseGVN* phase) const {
1970 Node* mem = in(MemNode::Memory);
1971 Node* value = can_see_stored_value(mem,phase);
1972 if (value != NULL && value->is_Con() &&
1973 !value->bottom_type()->higher_equal(_type)) {
1974 // If the input to the store does not fit with the load's result type,
1975 // it must be truncated. We can't delay until Ideal call since
1976 // a singleton Value is needed for split_thru_phi optimization.
1977 int con = value->get_int();
1978 return TypeInt::make((con << 24) >> 24);
1979 }
1980 return LoadNode::Value(phase);
1981 }
1982
1983 //--------------------------LoadUBNode::Ideal-------------------------------------
1984 //
1985 // If the previous store is to the same address as this load,
1986 // and the value stored was larger than a byte, replace this load
1987 // with the value stored truncated to a byte. If no truncation is
1988 // needed, the replacement is done in LoadNode::Identity().
1989 //
1990 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
1991 Node* mem = in(MemNode::Memory);
1992 Node* value = can_see_stored_value(mem, phase);
1993 if (value && !phase->type(value)->higher_equal(_type))
1994 return new AndINode(value, phase->intcon(0xFF));
1995 // Identity call will handle the case where truncation is not needed.
1996 return LoadNode::Ideal(phase, can_reshape);
1997 }
1998
1999 const Type* LoadUBNode::Value(PhaseGVN* phase) const {
2000 Node* mem = in(MemNode::Memory);
2001 Node* value = can_see_stored_value(mem,phase);
2002 if (value != NULL && value->is_Con() &&
2003 !value->bottom_type()->higher_equal(_type)) {
2004 // If the input to the store does not fit with the load's result type,
2005 // it must be truncated. We can't delay until Ideal call since
2006 // a singleton Value is needed for split_thru_phi optimization.
2007 int con = value->get_int();
2008 return TypeInt::make(con & 0xFF);
2009 }
2010 return LoadNode::Value(phase);
2011 }
2012
2013 //--------------------------LoadUSNode::Ideal-------------------------------------
2014 //
2015 // If the previous store is to the same address as this load,
2016 // and the value stored was larger than a char, replace this load
2017 // with the value stored truncated to a char. If no truncation is
2018 // needed, the replacement is done in LoadNode::Identity().
2019 //
2020 Node *LoadUSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2021 Node* mem = in(MemNode::Memory);
2022 Node* value = can_see_stored_value(mem,phase);
2023 if( value && !phase->type(value)->higher_equal( _type ) )
2024 return new AndINode(value,phase->intcon(0xFFFF));
2025 // Identity call will handle the case where truncation is not needed.
2026 return LoadNode::Ideal(phase, can_reshape);
2027 }
2028
2029 const Type* LoadUSNode::Value(PhaseGVN* phase) const {
2030 Node* mem = in(MemNode::Memory);
2031 Node* value = can_see_stored_value(mem,phase);
2032 if (value != NULL && value->is_Con() &&
2033 !value->bottom_type()->higher_equal(_type)) {
2034 // If the input to the store does not fit with the load's result type,
2035 // it must be truncated. We can't delay until Ideal call since
2036 // a singleton Value is needed for split_thru_phi optimization.
2037 int con = value->get_int();
2038 return TypeInt::make(con & 0xFFFF);
2039 }
2040 return LoadNode::Value(phase);
2041 }
2042
2043 //--------------------------LoadSNode::Ideal--------------------------------------
2044 //
2045 // If the previous store is to the same address as this load,
2046 // and the value stored was larger than a short, replace this load
2047 // with the value stored truncated to a short. If no truncation is
2048 // needed, the replacement is done in LoadNode::Identity().
2049 //
2050 Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2051 Node* mem = in(MemNode::Memory);
2052 Node* value = can_see_stored_value(mem,phase);
2053 if( value && !phase->type(value)->higher_equal( _type ) ) {
2054 Node *result = phase->transform( new LShiftINode(value, phase->intcon(16)) );
2055 return new RShiftINode(result, phase->intcon(16));
2056 }
2057 // Identity call will handle the case where truncation is not needed.
2058 return LoadNode::Ideal(phase, can_reshape);
2059 }
2060
2061 const Type* LoadSNode::Value(PhaseGVN* phase) const {
2062 Node* mem = in(MemNode::Memory);
2063 Node* value = can_see_stored_value(mem,phase);
2064 if (value != NULL && value->is_Con() &&
2065 !value->bottom_type()->higher_equal(_type)) {
2066 // If the input to the store does not fit with the load's result type,
2067 // it must be truncated. We can't delay until Ideal call since
2068 // a singleton Value is needed for split_thru_phi optimization.
2069 int con = value->get_int();
2070 return TypeInt::make((con << 16) >> 16);
2071 }
2072 return LoadNode::Value(phase);
2073 }
2074
2075 //=============================================================================
2076 //----------------------------LoadKlassNode::make------------------------------
2077 // Polymorphic factory method:
2078 Node* LoadKlassNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* at, const TypeKlassPtr* tk) {
2079 // sanity check the alias category against the created node type
2080 const TypePtr *adr_type = adr->bottom_type()->isa_ptr();
2081 assert(adr_type != NULL, "expecting TypeKlassPtr");
2082 #ifdef _LP64
2083 if (adr_type->is_ptr_to_narrowklass()) {
2084 assert(UseCompressedClassPointers, "no compressed klasses");
2085 Node* load_klass = gvn.transform(new LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowklass(), MemNode::unordered));
2086 return new DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr());
2087 }
2088 #endif
2089 assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
2090 return new LoadKlassNode(ctl, mem, adr, at, tk, MemNode::unordered);
2091 }
2092
2093 //------------------------------Value------------------------------------------
2094 const Type* LoadKlassNode::Value(PhaseGVN* phase) const {
2095 return klass_value_common(phase);
2096 }
2097
2098 // In most cases, LoadKlassNode does not have the control input set. If the control
2099 // input is set, it must not be removed (by LoadNode::Ideal()).
2100 bool LoadKlassNode::can_remove_control() const {
2101 return false;
2102 }
2103
2104 const Type* LoadNode::klass_value_common(PhaseGVN* phase) const {
2105 // Either input is TOP ==> the result is TOP
2106 const Type *t1 = phase->type( in(MemNode::Memory) );
2107 if (t1 == Type::TOP) return Type::TOP;
2108 Node *adr = in(MemNode::Address);
2109 const Type *t2 = phase->type( adr );
2110 if (t2 == Type::TOP) return Type::TOP;
2111 const TypePtr *tp = t2->is_ptr();
2112 if (TypePtr::above_centerline(tp->ptr()) ||
2113 tp->ptr() == TypePtr::Null) return Type::TOP;
2114
2115 // Return a more precise klass, if possible
2116 const TypeInstPtr *tinst = tp->isa_instptr();
2117 if (tinst != NULL) {
2118 ciInstanceKlass* ik = tinst->klass()->as_instance_klass();
2119 int offset = tinst->offset();
2120 if (ik == phase->C->env()->Class_klass()
2121 && (offset == java_lang_Class::klass_offset_in_bytes() ||
2122 offset == java_lang_Class::array_klass_offset_in_bytes())) {
2123 // We are loading a special hidden field from a Class mirror object,
2124 // the field which points to the VM's Klass metaobject.
2125 ciType* t = tinst->java_mirror_type();
2126 // java_mirror_type returns non-null for compile-time Class constants.
2127 if (t != NULL) {
2128 // constant oop => constant klass
2129 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
2130 if (t->is_void()) {
2131 // We cannot create a void array. Since void is a primitive type return null
2132 // klass. Users of this result need to do a null check on the returned klass.
2133 return TypePtr::NULL_PTR;
2134 }
2135 return TypeKlassPtr::make(ciArrayKlass::make(t));
2136 }
2137 if (!t->is_klass()) {
2138 // a primitive Class (e.g., int.class) has NULL for a klass field
2139 return TypePtr::NULL_PTR;
2140 }
2141 // (Folds up the 1st indirection in aClassConstant.getModifiers().)
2142 return TypeKlassPtr::make(t->as_klass());
2143 }
2144 // non-constant mirror, so we can't tell what's going on
2145 }
2146 if( !ik->is_loaded() )
2147 return _type; // Bail out if not loaded
2148 if (offset == oopDesc::klass_offset_in_bytes()) {
2149 if (tinst->klass_is_exact()) {
2150 return TypeKlassPtr::make(ik);
2151 }
2152 // See if we can become precise: no subklasses and no interface
2153 // (Note: We need to support verified interfaces.)
2154 if (!ik->is_interface() && !ik->has_subklass()) {
2155 //assert(!UseExactTypes, "this code should be useless with exact types");
2156 // Add a dependence; if any subclass added we need to recompile
2157 if (!ik->is_final()) {
2158 // %%% should use stronger assert_unique_concrete_subtype instead
2159 phase->C->dependencies()->assert_leaf_type(ik);
2160 }
2161 // Return precise klass
2162 return TypeKlassPtr::make(ik);
2163 }
2164
2165 // Return root of possible klass
2166 return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/);
2167 }
2168 }
2169
2170 // Check for loading klass from an array
2171 const TypeAryPtr *tary = tp->isa_aryptr();
2172 if( tary != NULL ) {
2173 ciKlass *tary_klass = tary->klass();
2174 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP
2175 && tary->offset() == oopDesc::klass_offset_in_bytes()) {
2176 if (tary->klass_is_exact()) {
2177 return TypeKlassPtr::make(tary_klass);
2178 }
2179 ciArrayKlass *ak = tary->klass()->as_array_klass();
2180 // If the klass is an object array, we defer the question to the
2181 // array component klass.
2182 if( ak->is_obj_array_klass() ) {
2183 assert( ak->is_loaded(), "" );
2184 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass();
2185 if( base_k->is_loaded() && base_k->is_instance_klass() ) {
2186 ciInstanceKlass* ik = base_k->as_instance_klass();
2187 // See if we can become precise: no subklasses and no interface
2188 if (!ik->is_interface() && !ik->has_subklass()) {
2189 //assert(!UseExactTypes, "this code should be useless with exact types");
2190 // Add a dependence; if any subclass added we need to recompile
2191 if (!ik->is_final()) {
2192 phase->C->dependencies()->assert_leaf_type(ik);
2193 }
2194 // Return precise array klass
2195 return TypeKlassPtr::make(ak);
2196 }
2197 }
2198 return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/);
2199 } else { // Found a type-array?
2200 //assert(!UseExactTypes, "this code should be useless with exact types");
2201 assert( ak->is_type_array_klass(), "" );
2202 return TypeKlassPtr::make(ak); // These are always precise
2203 }
2204 }
2205 }
2206
2207 // Check for loading klass from an array klass
2208 const TypeKlassPtr *tkls = tp->isa_klassptr();
2209 if (tkls != NULL && !StressReflectiveCode) {
2210 ciKlass* klass = tkls->klass();
2211 if( !klass->is_loaded() )
2212 return _type; // Bail out if not loaded
2213 if( klass->is_obj_array_klass() &&
2214 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) {
2215 ciKlass* elem = klass->as_obj_array_klass()->element_klass();
2216 // // Always returning precise element type is incorrect,
2217 // // e.g., element type could be object and array may contain strings
2218 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
2219
2220 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
2221 // according to the element type's subclassing.
2222 return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/);
2223 }
2224 if( klass->is_instance_klass() && tkls->klass_is_exact() &&
2225 tkls->offset() == in_bytes(Klass::super_offset())) {
2226 ciKlass* sup = klass->as_instance_klass()->super();
2227 // The field is Klass::_super. Return its (constant) value.
2228 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
2229 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR;
2230 }
2231 }
2232
2233 // Bailout case
2234 return LoadNode::Value(phase);
2235 }
2236
2237 //------------------------------Identity---------------------------------------
2238 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
2239 // Also feed through the klass in Allocate(...klass...)._klass.
2240 Node* LoadKlassNode::Identity(PhaseGVN* phase) {
2241 return klass_identity_common(phase);
2242 }
2243
2244 Node* LoadNode::klass_identity_common(PhaseGVN* phase) {
2245 Node* x = LoadNode::Identity(phase);
2246 if (x != this) return x;
2247
2248 // Take apart the address into an oop and and offset.
2249 // Return 'this' if we cannot.
2250 Node* adr = in(MemNode::Address);
2251 intptr_t offset = 0;
2252 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2253 if (base == NULL) return this;
2254 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
2255 if (toop == NULL) return this;
2256
2257 // Step over potential GC barrier for OopHandle resolve
2258 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
2259 if (bs->is_gc_barrier_node(base)) {
2260 base = bs->step_over_gc_barrier(base);
2261 }
2262
2263 // We can fetch the klass directly through an AllocateNode.
2264 // This works even if the klass is not constant (clone or newArray).
2265 if (offset == oopDesc::klass_offset_in_bytes()) {
2266 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
2267 if (allocated_klass != NULL) {
2268 return allocated_klass;
2269 }
2270 }
2271
2272 // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*.
2273 // See inline_native_Class_query for occurrences of these patterns.
2274 // Java Example: x.getClass().isAssignableFrom(y)
2275 //
2276 // This improves reflective code, often making the Class
2277 // mirror go completely dead. (Current exception: Class
2278 // mirrors may appear in debug info, but we could clean them out by
2279 // introducing a new debug info operator for Klass.java_mirror).
2280
2281 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass()
2282 && offset == java_lang_Class::klass_offset_in_bytes()) {
2283 if (base->is_Load()) {
2284 Node* base2 = base->in(MemNode::Address);
2285 if (base2->is_Load()) { /* direct load of a load which is the OopHandle */
2286 Node* adr2 = base2->in(MemNode::Address);
2287 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2288 if (tkls != NULL && !tkls->empty()
2289 && (tkls->klass()->is_instance_klass() ||
2290 tkls->klass()->is_array_klass())
2291 && adr2->is_AddP()
2292 ) {
2293 int mirror_field = in_bytes(Klass::java_mirror_offset());
2294 if (tkls->offset() == mirror_field) {
2295 return adr2->in(AddPNode::Base);
2296 }
2297 }
2298 }
2299 }
2300 }
2301
2302 return this;
2303 }
2304
2305
2306 //------------------------------Value------------------------------------------
2307 const Type* LoadNKlassNode::Value(PhaseGVN* phase) const {
2308 const Type *t = klass_value_common(phase);
2309 if (t == Type::TOP)
2310 return t;
2311
2312 return t->make_narrowklass();
2313 }
2314
2315 //------------------------------Identity---------------------------------------
2316 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
2317 // Also feed through the klass in Allocate(...klass...)._klass.
2318 Node* LoadNKlassNode::Identity(PhaseGVN* phase) {
2319 Node *x = klass_identity_common(phase);
2320
2321 const Type *t = phase->type( x );
2322 if( t == Type::TOP ) return x;
2323 if( t->isa_narrowklass()) return x;
2324 assert (!t->isa_narrowoop(), "no narrow oop here");
2325
2326 return phase->transform(new EncodePKlassNode(x, t->make_narrowklass()));
2327 }
2328
2329 //------------------------------Value-----------------------------------------
2330 const Type* LoadRangeNode::Value(PhaseGVN* phase) const {
2331 // Either input is TOP ==> the result is TOP
2332 const Type *t1 = phase->type( in(MemNode::Memory) );
2333 if( t1 == Type::TOP ) return Type::TOP;
2334 Node *adr = in(MemNode::Address);
2335 const Type *t2 = phase->type( adr );
2336 if( t2 == Type::TOP ) return Type::TOP;
2337 const TypePtr *tp = t2->is_ptr();
2338 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
2339 const TypeAryPtr *tap = tp->isa_aryptr();
2340 if( !tap ) return _type;
2341 return tap->size();
2342 }
2343
2344 //-------------------------------Ideal---------------------------------------
2345 // Feed through the length in AllocateArray(...length...)._length.
2346 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2347 Node* p = MemNode::Ideal_common(phase, can_reshape);
2348 if (p) return (p == NodeSentinel) ? NULL : p;
2349
2350 // Take apart the address into an oop and and offset.
2351 // Return 'this' if we cannot.
2352 Node* adr = in(MemNode::Address);
2353 intptr_t offset = 0;
2354 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2355 if (base == NULL) return NULL;
2356 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2357 if (tary == NULL) return NULL;
2358
2359 // We can fetch the length directly through an AllocateArrayNode.
2360 // This works even if the length is not constant (clone or newArray).
2361 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2362 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2363 if (alloc != NULL) {
2364 Node* allocated_length = alloc->Ideal_length();
2365 Node* len = alloc->make_ideal_length(tary, phase);
2366 if (allocated_length != len) {
2367 // New CastII improves on this.
2368 return len;
2369 }
2370 }
2371 }
2372
2373 return NULL;
2374 }
2375
2376 //------------------------------Identity---------------------------------------
2377 // Feed through the length in AllocateArray(...length...)._length.
2378 Node* LoadRangeNode::Identity(PhaseGVN* phase) {
2379 Node* x = LoadINode::Identity(phase);
2380 if (x != this) return x;
2381
2382 // Take apart the address into an oop and and offset.
2383 // Return 'this' if we cannot.
2384 Node* adr = in(MemNode::Address);
2385 intptr_t offset = 0;
2386 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2387 if (base == NULL) return this;
2388 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2389 if (tary == NULL) return this;
2390
2391 // We can fetch the length directly through an AllocateArrayNode.
2392 // This works even if the length is not constant (clone or newArray).
2393 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2394 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2395 if (alloc != NULL) {
2396 Node* allocated_length = alloc->Ideal_length();
2397 // Do not allow make_ideal_length to allocate a CastII node.
2398 Node* len = alloc->make_ideal_length(tary, phase, false);
2399 if (allocated_length == len) {
2400 // Return allocated_length only if it would not be improved by a CastII.
2401 return allocated_length;
2402 }
2403 }
2404 }
2405
2406 return this;
2407
2408 }
2409
2410 //=============================================================================
2411 //---------------------------StoreNode::make-----------------------------------
2412 // Polymorphic factory method:
2413 StoreNode* StoreNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt, MemOrd mo) {
2414 assert((mo == unordered || mo == release), "unexpected");
2415 Compile* C = gvn.C;
2416 assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2417 ctl != NULL, "raw memory operations should have control edge");
2418
2419 switch (bt) {
2420 case T_BOOLEAN: val = gvn.transform(new AndINode(val, gvn.intcon(0x1))); // Fall through to T_BYTE case
2421 case T_BYTE: return new StoreBNode(ctl, mem, adr, adr_type, val, mo);
2422 case T_INT: return new StoreINode(ctl, mem, adr, adr_type, val, mo);
2423 case T_CHAR:
2424 case T_SHORT: return new StoreCNode(ctl, mem, adr, adr_type, val, mo);
2425 case T_LONG: return new StoreLNode(ctl, mem, adr, adr_type, val, mo);
2426 case T_FLOAT: return new StoreFNode(ctl, mem, adr, adr_type, val, mo);
2427 case T_DOUBLE: return new StoreDNode(ctl, mem, adr, adr_type, val, mo);
2428 case T_METADATA:
2429 case T_ADDRESS:
2430 case T_OBJECT:
2431 #ifdef _LP64
2432 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
2433 val = gvn.transform(new EncodePNode(val, val->bottom_type()->make_narrowoop()));
2434 return new StoreNNode(ctl, mem, adr, adr_type, val, mo);
2435 } else if (adr->bottom_type()->is_ptr_to_narrowklass() ||
2436 (UseCompressedClassPointers && val->bottom_type()->isa_klassptr() &&
2437 adr->bottom_type()->isa_rawptr())) {
2438 val = gvn.transform(new EncodePKlassNode(val, val->bottom_type()->make_narrowklass()));
2439 return new StoreNKlassNode(ctl, mem, adr, adr_type, val, mo);
2440 }
2441 #endif
2442 {
2443 return new StorePNode(ctl, mem, adr, adr_type, val, mo);
2444 }
2445 default:
2446 ShouldNotReachHere();
2447 return (StoreNode*)NULL;
2448 }
2449 }
2450
2451 StoreLNode* StoreLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
2452 bool require_atomic = true;
2453 return new StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
2454 }
2455
2456 StoreDNode* StoreDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
2457 bool require_atomic = true;
2458 return new StoreDNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
2459 }
2460
2461
2462 //--------------------------bottom_type----------------------------------------
2463 const Type *StoreNode::bottom_type() const {
2464 return Type::MEMORY;
2465 }
2466
2467 //------------------------------hash-------------------------------------------
2468 uint StoreNode::hash() const {
2469 // unroll addition of interesting fields
2470 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2471
2472 // Since they are not commoned, do not hash them:
2473 return NO_HASH;
2474 }
2475
2476 //------------------------------Ideal------------------------------------------
2477 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
2478 // When a store immediately follows a relevant allocation/initialization,
2479 // try to capture it into the initialization, or hoist it above.
2480 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2481 Node* p = MemNode::Ideal_common(phase, can_reshape);
2482 if (p) return (p == NodeSentinel) ? NULL : p;
2483
2484 Node* mem = in(MemNode::Memory);
2485 Node* address = in(MemNode::Address);
2486 // Back-to-back stores to same address? Fold em up. Generally
2487 // unsafe if I have intervening uses... Also disallowed for StoreCM
2488 // since they must follow each StoreP operation. Redundant StoreCMs
2489 // are eliminated just before matching in final_graph_reshape.
2490 {
2491 Node* st = mem;
2492 // If Store 'st' has more than one use, we cannot fold 'st' away.
2493 // For example, 'st' might be the final state at a conditional
2494 // return. Or, 'st' might be used by some node which is live at
2495 // the same time 'st' is live, which might be unschedulable. So,
2496 // require exactly ONE user until such time as we clone 'mem' for
2497 // each of 'mem's uses (thus making the exactly-1-user-rule hold
2498 // true).
2499 while (st->is_Store() && st->outcnt() == 1 && st->Opcode() != Op_StoreCM) {
2500 // Looking at a dead closed cycle of memory?
2501 assert(st != st->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
2502 assert(Opcode() == st->Opcode() ||
2503 st->Opcode() == Op_StoreVector ||
2504 Opcode() == Op_StoreVector ||
2505 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw ||
2506 (Opcode() == Op_StoreL && st->Opcode() == Op_StoreI) || // expanded ClearArrayNode
2507 (Opcode() == Op_StoreI && st->Opcode() == Op_StoreL) || // initialization by arraycopy
2508 (is_mismatched_access() || st->as_Store()->is_mismatched_access()),
2509 "no mismatched stores, except on raw memory: %s %s", NodeClassNames[Opcode()], NodeClassNames[st->Opcode()]);
2510
2511 if (st->in(MemNode::Address)->eqv_uncast(address) &&
2512 st->as_Store()->memory_size() <= this->memory_size()) {
2513 Node* use = st->raw_out(0);
2514 phase->igvn_rehash_node_delayed(use);
2515 if (can_reshape) {
2516 use->set_req_X(MemNode::Memory, st->in(MemNode::Memory), phase->is_IterGVN());
2517 } else {
2518 // It's OK to do this in the parser, since DU info is always accurate,
2519 // and the parser always refers to nodes via SafePointNode maps.
2520 use->set_req(MemNode::Memory, st->in(MemNode::Memory));
2521 }
2522 return this;
2523 }
2524 st = st->in(MemNode::Memory);
2525 }
2526 }
2527
2528
2529 // Capture an unaliased, unconditional, simple store into an initializer.
2530 // Or, if it is independent of the allocation, hoist it above the allocation.
2531 if (ReduceFieldZeroing && /*can_reshape &&*/
2532 mem->is_Proj() && mem->in(0)->is_Initialize()) {
2533 InitializeNode* init = mem->in(0)->as_Initialize();
2534 intptr_t offset = init->can_capture_store(this, phase, can_reshape);
2535 if (offset > 0) {
2536 Node* moved = init->capture_store(this, offset, phase, can_reshape);
2537 // If the InitializeNode captured me, it made a raw copy of me,
2538 // and I need to disappear.
2539 if (moved != NULL) {
2540 // %%% hack to ensure that Ideal returns a new node:
2541 mem = MergeMemNode::make(mem);
2542 return mem; // fold me away
2543 }
2544 }
2545 }
2546
2547 return NULL; // No further progress
2548 }
2549
2550 //------------------------------Value-----------------------------------------
2551 const Type* StoreNode::Value(PhaseGVN* phase) const {
2552 // Either input is TOP ==> the result is TOP
2553 const Type *t1 = phase->type( in(MemNode::Memory) );
2554 if( t1 == Type::TOP ) return Type::TOP;
2555 const Type *t2 = phase->type( in(MemNode::Address) );
2556 if( t2 == Type::TOP ) return Type::TOP;
2557 const Type *t3 = phase->type( in(MemNode::ValueIn) );
2558 if( t3 == Type::TOP ) return Type::TOP;
2559 return Type::MEMORY;
2560 }
2561
2562 //------------------------------Identity---------------------------------------
2563 // Remove redundant stores:
2564 // Store(m, p, Load(m, p)) changes to m.
2565 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
2566 Node* StoreNode::Identity(PhaseGVN* phase) {
2567 Node* mem = in(MemNode::Memory);
2568 Node* adr = in(MemNode::Address);
2569 Node* val = in(MemNode::ValueIn);
2570
2571 Node* result = this;
2572
2573 // Load then Store? Then the Store is useless
2574 if (val->is_Load() &&
2575 val->in(MemNode::Address)->eqv_uncast(adr) &&
2576 val->in(MemNode::Memory )->eqv_uncast(mem) &&
2577 val->as_Load()->store_Opcode() == Opcode()) {
2578 result = mem;
2579 }
2580
2581 // Two stores in a row of the same value?
2582 if (result == this &&
2583 mem->is_Store() &&
2584 mem->in(MemNode::Address)->eqv_uncast(adr) &&
2585 mem->in(MemNode::ValueIn)->eqv_uncast(val) &&
2586 mem->Opcode() == Opcode()) {
2587 result = mem;
2588 }
2589
2590 // Store of zero anywhere into a freshly-allocated object?
2591 // Then the store is useless.
2592 // (It must already have been captured by the InitializeNode.)
2593 if (result == this &&
2594 ReduceFieldZeroing && phase->type(val)->is_zero_type()) {
2595 // a newly allocated object is already all-zeroes everywhere
2596 if (mem->is_Proj() && mem->in(0)->is_Allocate()) {
2597 result = mem;
2598 }
2599
2600 if (result == this) {
2601 // the store may also apply to zero-bits in an earlier object
2602 Node* prev_mem = find_previous_store(phase);
2603 // Steps (a), (b): Walk past independent stores to find an exact match.
2604 if (prev_mem != NULL) {
2605 Node* prev_val = can_see_stored_value(prev_mem, phase);
2606 if (prev_val != NULL && phase->eqv(prev_val, val)) {
2607 // prev_val and val might differ by a cast; it would be good
2608 // to keep the more informative of the two.
2609 result = mem;
2610 }
2611 }
2612 }
2613 }
2614
2615 if (result != this && phase->is_IterGVN() != NULL) {
2616 MemBarNode* trailing = trailing_membar();
2617 if (trailing != NULL) {
2618 #ifdef ASSERT
2619 const TypeOopPtr* t_oop = phase->type(in(Address))->isa_oopptr();
2620 assert(t_oop == NULL || t_oop->is_known_instance_field(), "only for non escaping objects");
2621 #endif
2622 PhaseIterGVN* igvn = phase->is_IterGVN();
2623 trailing->remove(igvn);
2624 }
2625 }
2626
2627 return result;
2628 }
2629
2630 //------------------------------match_edge-------------------------------------
2631 // Do we Match on this edge index or not? Match only memory & value
2632 uint StoreNode::match_edge(uint idx) const {
2633 return idx == MemNode::Address || idx == MemNode::ValueIn;
2634 }
2635
2636 //------------------------------cmp--------------------------------------------
2637 // Do not common stores up together. They generally have to be split
2638 // back up anyways, so do not bother.
2639 uint StoreNode::cmp( const Node &n ) const {
2640 return (&n == this); // Always fail except on self
2641 }
2642
2643 //------------------------------Ideal_masked_input-----------------------------
2644 // Check for a useless mask before a partial-word store
2645 // (StoreB ... (AndI valIn conIa) )
2646 // If (conIa & mask == mask) this simplifies to
2647 // (StoreB ... (valIn) )
2648 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
2649 Node *val = in(MemNode::ValueIn);
2650 if( val->Opcode() == Op_AndI ) {
2651 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2652 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
2653 set_req(MemNode::ValueIn, val->in(1));
2654 return this;
2655 }
2656 }
2657 return NULL;
2658 }
2659
2660
2661 //------------------------------Ideal_sign_extended_input----------------------
2662 // Check for useless sign-extension before a partial-word store
2663 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) )
2664 // If (conIL == conIR && conIR <= num_bits) this simplifies to
2665 // (StoreB ... (valIn) )
2666 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) {
2667 Node *val = in(MemNode::ValueIn);
2668 if( val->Opcode() == Op_RShiftI ) {
2669 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2670 if( t && t->is_con() && (t->get_con() <= num_bits) ) {
2671 Node *shl = val->in(1);
2672 if( shl->Opcode() == Op_LShiftI ) {
2673 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int();
2674 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) {
2675 set_req(MemNode::ValueIn, shl->in(1));
2676 return this;
2677 }
2678 }
2679 }
2680 }
2681 return NULL;
2682 }
2683
2684 //------------------------------value_never_loaded-----------------------------------
2685 // Determine whether there are any possible loads of the value stored.
2686 // For simplicity, we actually check if there are any loads from the
2687 // address stored to, not just for loads of the value stored by this node.
2688 //
2689 bool StoreNode::value_never_loaded( PhaseTransform *phase) const {
2690 Node *adr = in(Address);
2691 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
2692 if (adr_oop == NULL)
2693 return false;
2694 if (!adr_oop->is_known_instance_field())
2695 return false; // if not a distinct instance, there may be aliases of the address
2696 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
2697 Node *use = adr->fast_out(i);
2698 if (use->is_Load() || use->is_LoadStore()) {
2699 return false;
2700 }
2701 }
2702 return true;
2703 }
2704
2705 MemBarNode* StoreNode::trailing_membar() const {
2706 if (is_release()) {
2707 MemBarNode* trailing_mb = NULL;
2708 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
2709 Node* u = fast_out(i);
2710 if (u->is_MemBar()) {
2711 if (u->as_MemBar()->trailing_store()) {
2712 assert(u->Opcode() == Op_MemBarVolatile, "");
2713 assert(trailing_mb == NULL, "only one");
2714 trailing_mb = u->as_MemBar();
2715 #ifdef ASSERT
2716 Node* leading = u->as_MemBar()->leading_membar();
2717 assert(leading->Opcode() == Op_MemBarRelease, "incorrect membar");
2718 assert(leading->as_MemBar()->leading_store(), "incorrect membar pair");
2719 assert(leading->as_MemBar()->trailing_membar() == u, "incorrect membar pair");
2720 #endif
2721 } else {
2722 assert(u->as_MemBar()->standalone(), "");
2723 }
2724 }
2725 }
2726 return trailing_mb;
2727 }
2728 return NULL;
2729 }
2730
2731
2732 //=============================================================================
2733 //------------------------------Ideal------------------------------------------
2734 // If the store is from an AND mask that leaves the low bits untouched, then
2735 // we can skip the AND operation. If the store is from a sign-extension
2736 // (a left shift, then right shift) we can skip both.
2737 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
2738 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
2739 if( progress != NULL ) return progress;
2740
2741 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
2742 if( progress != NULL ) return progress;
2743
2744 // Finally check the default case
2745 return StoreNode::Ideal(phase, can_reshape);
2746 }
2747
2748 //=============================================================================
2749 //------------------------------Ideal------------------------------------------
2750 // If the store is from an AND mask that leaves the low bits untouched, then
2751 // we can skip the AND operation
2752 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
2753 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
2754 if( progress != NULL ) return progress;
2755
2756 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
2757 if( progress != NULL ) return progress;
2758
2759 // Finally check the default case
2760 return StoreNode::Ideal(phase, can_reshape);
2761 }
2762
2763 //=============================================================================
2764 //------------------------------Identity---------------------------------------
2765 Node* StoreCMNode::Identity(PhaseGVN* phase) {
2766 // No need to card mark when storing a null ptr
2767 Node* my_store = in(MemNode::OopStore);
2768 if (my_store->is_Store()) {
2769 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) );
2770 if( t1 == TypePtr::NULL_PTR ) {
2771 return in(MemNode::Memory);
2772 }
2773 }
2774 return this;
2775 }
2776
2777 //=============================================================================
2778 //------------------------------Ideal---------------------------------------
2779 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){
2780 Node* progress = StoreNode::Ideal(phase, can_reshape);
2781 if (progress != NULL) return progress;
2782
2783 Node* my_store = in(MemNode::OopStore);
2784 if (my_store->is_MergeMem()) {
2785 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx());
2786 set_req(MemNode::OopStore, mem);
2787 return this;
2788 }
2789
2790 return NULL;
2791 }
2792
2793 //------------------------------Value-----------------------------------------
2794 const Type* StoreCMNode::Value(PhaseGVN* phase) const {
2795 // Either input is TOP ==> the result is TOP
2796 const Type *t = phase->type( in(MemNode::Memory) );
2797 if( t == Type::TOP ) return Type::TOP;
2798 t = phase->type( in(MemNode::Address) );
2799 if( t == Type::TOP ) return Type::TOP;
2800 t = phase->type( in(MemNode::ValueIn) );
2801 if( t == Type::TOP ) return Type::TOP;
2802 // If extra input is TOP ==> the result is TOP
2803 t = phase->type( in(MemNode::OopStore) );
2804 if( t == Type::TOP ) return Type::TOP;
2805
2806 return StoreNode::Value( phase );
2807 }
2808
2809
2810 //=============================================================================
2811 //----------------------------------SCMemProjNode------------------------------
2812 const Type* SCMemProjNode::Value(PhaseGVN* phase) const
2813 {
2814 return bottom_type();
2815 }
2816
2817 //=============================================================================
2818 //----------------------------------LoadStoreNode------------------------------
2819 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required )
2820 : Node(required),
2821 _type(rt),
2822 _adr_type(at)
2823 {
2824 init_req(MemNode::Control, c );
2825 init_req(MemNode::Memory , mem);
2826 init_req(MemNode::Address, adr);
2827 init_req(MemNode::ValueIn, val);
2828 init_class_id(Class_LoadStore);
2829 }
2830
2831 uint LoadStoreNode::ideal_reg() const {
2832 return _type->ideal_reg();
2833 }
2834
2835 bool LoadStoreNode::result_not_used() const {
2836 for( DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++ ) {
2837 Node *x = fast_out(i);
2838 if (x->Opcode() == Op_SCMemProj) continue;
2839 return false;
2840 }
2841 return true;
2842 }
2843
2844 MemBarNode* LoadStoreNode::trailing_membar() const {
2845 MemBarNode* trailing = NULL;
2846 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
2847 Node* u = fast_out(i);
2848 if (u->is_MemBar()) {
2849 if (u->as_MemBar()->trailing_load_store()) {
2850 assert(u->Opcode() == Op_MemBarAcquire, "");
2851 assert(trailing == NULL, "only one");
2852 trailing = u->as_MemBar();
2853 #ifdef ASSERT
2854 Node* leading = trailing->leading_membar();
2855 assert(support_IRIW_for_not_multiple_copy_atomic_cpu || leading->Opcode() == Op_MemBarRelease, "incorrect membar");
2856 assert(leading->as_MemBar()->leading_load_store(), "incorrect membar pair");
2857 assert(leading->as_MemBar()->trailing_membar() == trailing, "incorrect membar pair");
2858 #endif
2859 } else {
2860 assert(u->as_MemBar()->standalone(), "wrong barrier kind");
2861 }
2862 }
2863 }
2864
2865 return trailing;
2866 }
2867
2868 uint LoadStoreNode::size_of() const { return sizeof(*this); }
2869
2870 //=============================================================================
2871 //----------------------------------LoadStoreConditionalNode--------------------
2872 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, NULL, TypeInt::BOOL, 5) {
2873 init_req(ExpectedIn, ex );
2874 }
2875
2876 //=============================================================================
2877 //-------------------------------adr_type--------------------------------------
2878 const TypePtr* ClearArrayNode::adr_type() const {
2879 Node *adr = in(3);
2880 if (adr == NULL) return NULL; // node is dead
2881 return MemNode::calculate_adr_type(adr->bottom_type());
2882 }
2883
2884 //------------------------------match_edge-------------------------------------
2885 // Do we Match on this edge index or not? Do not match memory
2886 uint ClearArrayNode::match_edge(uint idx) const {
2887 return idx > 1;
2888 }
2889
2890 //------------------------------Identity---------------------------------------
2891 // Clearing a zero length array does nothing
2892 Node* ClearArrayNode::Identity(PhaseGVN* phase) {
2893 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
2894 }
2895
2896 //------------------------------Idealize---------------------------------------
2897 // Clearing a short array is faster with stores
2898 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2899 // Already know this is a large node, do not try to ideal it
2900 if (!IdealizeClearArrayNode || _is_large) return NULL;
2901
2902 const int unit = BytesPerLong;
2903 const TypeX* t = phase->type(in(2))->isa_intptr_t();
2904 if (!t) return NULL;
2905 if (!t->is_con()) return NULL;
2906 intptr_t raw_count = t->get_con();
2907 intptr_t size = raw_count;
2908 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
2909 // Clearing nothing uses the Identity call.
2910 // Negative clears are possible on dead ClearArrays
2911 // (see jck test stmt114.stmt11402.val).
2912 if (size <= 0 || size % unit != 0) return NULL;
2913 intptr_t count = size / unit;
2914 // Length too long; communicate this to matchers and assemblers.
2915 // Assemblers are responsible to produce fast hardware clears for it.
2916 if (size > InitArrayShortSize) {
2917 return new ClearArrayNode(in(0), in(1), in(2), in(3), true);
2918 }
2919 Node *mem = in(1);
2920 if( phase->type(mem)==Type::TOP ) return NULL;
2921 Node *adr = in(3);
2922 const Type* at = phase->type(adr);
2923 if( at==Type::TOP ) return NULL;
2924 const TypePtr* atp = at->isa_ptr();
2925 // adjust atp to be the correct array element address type
2926 if (atp == NULL) atp = TypePtr::BOTTOM;
2927 else atp = atp->add_offset(Type::OffsetBot);
2928 // Get base for derived pointer purposes
2929 if( adr->Opcode() != Op_AddP ) Unimplemented();
2930 Node *base = adr->in(1);
2931
2932 Node *zero = phase->makecon(TypeLong::ZERO);
2933 Node *off = phase->MakeConX(BytesPerLong);
2934 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
2935 count--;
2936 while( count-- ) {
2937 mem = phase->transform(mem);
2938 adr = phase->transform(new AddPNode(base,adr,off));
2939 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
2940 }
2941 return mem;
2942 }
2943
2944 //----------------------------step_through----------------------------------
2945 // Return allocation input memory edge if it is different instance
2946 // or itself if it is the one we are looking for.
2947 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) {
2948 Node* n = *np;
2949 assert(n->is_ClearArray(), "sanity");
2950 intptr_t offset;
2951 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
2952 // This method is called only before Allocate nodes are expanded
2953 // during macro nodes expansion. Before that ClearArray nodes are
2954 // only generated in PhaseMacroExpand::generate_arraycopy() (before
2955 // Allocate nodes are expanded) which follows allocations.
2956 assert(alloc != NULL, "should have allocation");
2957 if (alloc->_idx == instance_id) {
2958 // Can not bypass initialization of the instance we are looking for.
2959 return false;
2960 }
2961 // Otherwise skip it.
2962 InitializeNode* init = alloc->initialization();
2963 if (init != NULL)
2964 *np = init->in(TypeFunc::Memory);
2965 else
2966 *np = alloc->in(TypeFunc::Memory);
2967 return true;
2968 }
2969
2970 //----------------------------clear_memory-------------------------------------
2971 // Generate code to initialize object storage to zero.
2972 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2973 intptr_t start_offset,
2974 Node* end_offset,
2975 PhaseGVN* phase) {
2976 intptr_t offset = start_offset;
2977
2978 int unit = BytesPerLong;
2979 if ((offset % unit) != 0) {
2980 Node* adr = new AddPNode(dest, dest, phase->MakeConX(offset));
2981 adr = phase->transform(adr);
2982 const TypePtr* atp = TypeRawPtr::BOTTOM;
2983 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
2984 mem = phase->transform(mem);
2985 offset += BytesPerInt;
2986 }
2987 assert((offset % unit) == 0, "");
2988
2989 // Initialize the remaining stuff, if any, with a ClearArray.
2990 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase);
2991 }
2992
2993 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2994 Node* start_offset,
2995 Node* end_offset,
2996 PhaseGVN* phase) {
2997 if (start_offset == end_offset) {
2998 // nothing to do
2999 return mem;
3000 }
3001
3002 int unit = BytesPerLong;
3003 Node* zbase = start_offset;
3004 Node* zend = end_offset;
3005
3006 // Scale to the unit required by the CPU:
3007 if (!Matcher::init_array_count_is_in_bytes) {
3008 Node* shift = phase->intcon(exact_log2(unit));
3009 zbase = phase->transform(new URShiftXNode(zbase, shift) );
3010 zend = phase->transform(new URShiftXNode(zend, shift) );
3011 }
3012
3013 // Bulk clear double-words
3014 Node* zsize = phase->transform(new SubXNode(zend, zbase) );
3015 Node* adr = phase->transform(new AddPNode(dest, dest, start_offset) );
3016 mem = new ClearArrayNode(ctl, mem, zsize, adr, false);
3017 return phase->transform(mem);
3018 }
3019
3020 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
3021 intptr_t start_offset,
3022 intptr_t end_offset,
3023 PhaseGVN* phase) {
3024 if (start_offset == end_offset) {
3025 // nothing to do
3026 return mem;
3027 }
3028
3029 assert((end_offset % BytesPerInt) == 0, "odd end offset");
3030 intptr_t done_offset = end_offset;
3031 if ((done_offset % BytesPerLong) != 0) {
3032 done_offset -= BytesPerInt;
3033 }
3034 if (done_offset > start_offset) {
3035 mem = clear_memory(ctl, mem, dest,
3036 start_offset, phase->MakeConX(done_offset), phase);
3037 }
3038 if (done_offset < end_offset) { // emit the final 32-bit store
3039 Node* adr = new AddPNode(dest, dest, phase->MakeConX(done_offset));
3040 adr = phase->transform(adr);
3041 const TypePtr* atp = TypeRawPtr::BOTTOM;
3042 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
3043 mem = phase->transform(mem);
3044 done_offset += BytesPerInt;
3045 }
3046 assert(done_offset == end_offset, "");
3047 return mem;
3048 }
3049
3050 //=============================================================================
3051 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
3052 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)),
3053 _adr_type(C->get_adr_type(alias_idx)), _kind(Standalone)
3054 #ifdef ASSERT
3055 , _pair_idx(0)
3056 #endif
3057 {
3058 init_class_id(Class_MemBar);
3059 Node* top = C->top();
3060 init_req(TypeFunc::I_O,top);
3061 init_req(TypeFunc::FramePtr,top);
3062 init_req(TypeFunc::ReturnAdr,top);
3063 if (precedent != NULL)
3064 init_req(TypeFunc::Parms, precedent);
3065 }
3066
3067 //------------------------------cmp--------------------------------------------
3068 uint MemBarNode::hash() const { return NO_HASH; }
3069 uint MemBarNode::cmp( const Node &n ) const {
3070 return (&n == this); // Always fail except on self
3071 }
3072
3073 //------------------------------make-------------------------------------------
3074 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
3075 switch (opcode) {
3076 case Op_MemBarAcquire: return new MemBarAcquireNode(C, atp, pn);
3077 case Op_LoadFence: return new LoadFenceNode(C, atp, pn);
3078 case Op_MemBarRelease: return new MemBarReleaseNode(C, atp, pn);
3079 case Op_StoreFence: return new StoreFenceNode(C, atp, pn);
3080 case Op_MemBarAcquireLock: return new MemBarAcquireLockNode(C, atp, pn);
3081 case Op_MemBarReleaseLock: return new MemBarReleaseLockNode(C, atp, pn);
3082 case Op_MemBarVolatile: return new MemBarVolatileNode(C, atp, pn);
3083 case Op_MemBarCPUOrder: return new MemBarCPUOrderNode(C, atp, pn);
3084 case Op_OnSpinWait: return new OnSpinWaitNode(C, atp, pn);
3085 case Op_Initialize: return new InitializeNode(C, atp, pn);
3086 case Op_MemBarStoreStore: return new MemBarStoreStoreNode(C, atp, pn);
3087 default: ShouldNotReachHere(); return NULL;
3088 }
3089 }
3090
3091 void MemBarNode::remove(PhaseIterGVN *igvn) {
3092 if (outcnt() != 2) {
3093 return;
3094 }
3095 if (trailing_store() || trailing_load_store()) {
3096 MemBarNode* leading = leading_membar();
3097 if (leading != NULL) {
3098 assert(leading->trailing_membar() == this, "inconsistent leading/trailing membars");
3099 leading->remove(igvn);
3100 }
3101 }
3102 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
3103 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
3104 }
3105
3106 //------------------------------Ideal------------------------------------------
3107 // Return a node which is more "ideal" than the current node. Strip out
3108 // control copies
3109 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3110 if (remove_dead_region(phase, can_reshape)) return this;
3111 // Don't bother trying to transform a dead node
3112 if (in(0) && in(0)->is_top()) {
3113 return NULL;
3114 }
3115
3116 #if INCLUDE_ZGC
3117 if (UseZGC) {
3118 if (req() == (Precedent+1) && in(MemBarNode::Precedent)->in(0) != NULL && in(MemBarNode::Precedent)->in(0)->is_LoadBarrier()) {
3119 Node* load_node = in(MemBarNode::Precedent)->in(0)->in(LoadBarrierNode::Oop);
3120 set_req(MemBarNode::Precedent, load_node);
3121 return this;
3122 }
3123 }
3124 #endif
3125
3126 bool progress = false;
3127 // Eliminate volatile MemBars for scalar replaced objects.
3128 if (can_reshape && req() == (Precedent+1)) {
3129 bool eliminate = false;
3130 int opc = Opcode();
3131 if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) {
3132 // Volatile field loads and stores.
3133 Node* my_mem = in(MemBarNode::Precedent);
3134 // The MembarAquire may keep an unused LoadNode alive through the Precedent edge
3135 if ((my_mem != NULL) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) {
3136 // if the Precedent is a decodeN and its input (a Load) is used at more than one place,
3137 // replace this Precedent (decodeN) with the Load instead.
3138 if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1)) {
3139 Node* load_node = my_mem->in(1);
3140 set_req(MemBarNode::Precedent, load_node);
3141 phase->is_IterGVN()->_worklist.push(my_mem);
3142 my_mem = load_node;
3143 } else {
3144 assert(my_mem->unique_out() == this, "sanity");
3145 del_req(Precedent);
3146 phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later
3147 my_mem = NULL;
3148 }
3149 progress = true;
3150 }
3151 if (my_mem != NULL && my_mem->is_Mem()) {
3152 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
3153 // Check for scalar replaced object reference.
3154 if( t_oop != NULL && t_oop->is_known_instance_field() &&
3155 t_oop->offset() != Type::OffsetBot &&
3156 t_oop->offset() != Type::OffsetTop) {
3157 eliminate = true;
3158 }
3159 }
3160 } else if (opc == Op_MemBarRelease) {
3161 // Final field stores.
3162 Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent), phase);
3163 if ((alloc != NULL) && alloc->is_Allocate() &&
3164 alloc->as_Allocate()->does_not_escape_thread()) {
3165 // The allocated object does not escape.
3166 eliminate = true;
3167 }
3168 }
3169 if (eliminate) {
3170 // Replace MemBar projections by its inputs.
3171 PhaseIterGVN* igvn = phase->is_IterGVN();
3172 remove(igvn);
3173 // Must return either the original node (now dead) or a new node
3174 // (Do not return a top here, since that would break the uniqueness of top.)
3175 return new ConINode(TypeInt::ZERO);
3176 }
3177 }
3178 return progress ? this : NULL;
3179 }
3180
3181 //------------------------------Value------------------------------------------
3182 const Type* MemBarNode::Value(PhaseGVN* phase) const {
3183 if( !in(0) ) return Type::TOP;
3184 if( phase->type(in(0)) == Type::TOP )
3185 return Type::TOP;
3186 return TypeTuple::MEMBAR;
3187 }
3188
3189 //------------------------------match------------------------------------------
3190 // Construct projections for memory.
3191 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) {
3192 switch (proj->_con) {
3193 case TypeFunc::Control:
3194 case TypeFunc::Memory:
3195 return new MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
3196 }
3197 ShouldNotReachHere();
3198 return NULL;
3199 }
3200
3201 void MemBarNode::set_store_pair(MemBarNode* leading, MemBarNode* trailing) {
3202 trailing->_kind = TrailingStore;
3203 leading->_kind = LeadingStore;
3204 #ifdef ASSERT
3205 trailing->_pair_idx = leading->_idx;
3206 leading->_pair_idx = leading->_idx;
3207 #endif
3208 }
3209
3210 void MemBarNode::set_load_store_pair(MemBarNode* leading, MemBarNode* trailing) {
3211 trailing->_kind = TrailingLoadStore;
3212 leading->_kind = LeadingLoadStore;
3213 #ifdef ASSERT
3214 trailing->_pair_idx = leading->_idx;
3215 leading->_pair_idx = leading->_idx;
3216 #endif
3217 }
3218
3219 MemBarNode* MemBarNode::trailing_membar() const {
3220 ResourceMark rm;
3221 Node* trailing = (Node*)this;
3222 VectorSet seen(Thread::current()->resource_area());
3223 Node_Stack multis(0);
3224 do {
3225 Node* c = trailing;
3226 uint i = 0;
3227 do {
3228 trailing = NULL;
3229 for (; i < c->outcnt(); i++) {
3230 Node* next = c->raw_out(i);
3231 if (next != c && next->is_CFG()) {
3232 if (c->is_MultiBranch()) {
3233 if (multis.node() == c) {
3234 multis.set_index(i+1);
3235 } else {
3236 multis.push(c, i+1);
3237 }
3238 }
3239 trailing = next;
3240 break;
3241 }
3242 }
3243 if (trailing != NULL && !seen.test_set(trailing->_idx)) {
3244 break;
3245 }
3246 while (multis.size() > 0) {
3247 c = multis.node();
3248 i = multis.index();
3249 if (i < c->req()) {
3250 break;
3251 }
3252 multis.pop();
3253 }
3254 } while (multis.size() > 0);
3255 } while (!trailing->is_MemBar() || !trailing->as_MemBar()->trailing());
3256
3257 MemBarNode* mb = trailing->as_MemBar();
3258 assert((mb->_kind == TrailingStore && _kind == LeadingStore) ||
3259 (mb->_kind == TrailingLoadStore && _kind == LeadingLoadStore), "bad trailing membar");
3260 assert(mb->_pair_idx == _pair_idx, "bad trailing membar");
3261 return mb;
3262 }
3263
3264 MemBarNode* MemBarNode::leading_membar() const {
3265 ResourceMark rm;
3266 VectorSet seen(Thread::current()->resource_area());
3267 Node_Stack regions(0);
3268 Node* leading = in(0);
3269 while (leading != NULL && (!leading->is_MemBar() || !leading->as_MemBar()->leading())) {
3270 while (leading == NULL || leading->is_top() || seen.test_set(leading->_idx)) {
3271 leading = NULL;
3272 while (regions.size() > 0 && leading == NULL) {
3273 Node* r = regions.node();
3274 uint i = regions.index();
3275 if (i < r->req()) {
3276 leading = r->in(i);
3277 regions.set_index(i+1);
3278 } else {
3279 regions.pop();
3280 }
3281 }
3282 if (leading == NULL) {
3283 assert(regions.size() == 0, "all paths should have been tried");
3284 return NULL;
3285 }
3286 }
3287 if (leading->is_Region()) {
3288 regions.push(leading, 2);
3289 leading = leading->in(1);
3290 } else {
3291 leading = leading->in(0);
3292 }
3293 }
3294 #ifdef ASSERT
3295 Unique_Node_List wq;
3296 wq.push((Node*)this);
3297 uint found = 0;
3298 for (uint i = 0; i < wq.size(); i++) {
3299 Node* n = wq.at(i);
3300 if (n->is_Region()) {
3301 for (uint j = 1; j < n->req(); j++) {
3302 Node* in = n->in(j);
3303 if (in != NULL && !in->is_top()) {
3304 wq.push(in);
3305 }
3306 }
3307 } else {
3308 if (n->is_MemBar() && n->as_MemBar()->leading()) {
3309 assert(n == leading, "consistency check failed");
3310 found++;
3311 } else {
3312 Node* in = n->in(0);
3313 if (in != NULL && !in->is_top()) {
3314 wq.push(in);
3315 }
3316 }
3317 }
3318 }
3319 assert(found == 1 || (found == 0 && leading == NULL), "consistency check failed");
3320 #endif
3321 if (leading == NULL) {
3322 return NULL;
3323 }
3324 MemBarNode* mb = leading->as_MemBar();
3325 assert((mb->_kind == LeadingStore && _kind == TrailingStore) ||
3326 (mb->_kind == LeadingLoadStore && _kind == TrailingLoadStore), "bad leading membar");
3327 assert(mb->_pair_idx == _pair_idx, "bad leading membar");
3328 return mb;
3329 }
3330
3331 //===========================InitializeNode====================================
3332 // SUMMARY:
3333 // This node acts as a memory barrier on raw memory, after some raw stores.
3334 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
3335 // The Initialize can 'capture' suitably constrained stores as raw inits.
3336 // It can coalesce related raw stores into larger units (called 'tiles').
3337 // It can avoid zeroing new storage for memory units which have raw inits.
3338 // At macro-expansion, it is marked 'complete', and does not optimize further.
3339 //
3340 // EXAMPLE:
3341 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
3342 // ctl = incoming control; mem* = incoming memory
3343 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
3344 // First allocate uninitialized memory and fill in the header:
3345 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
3346 // ctl := alloc.Control; mem* := alloc.Memory*
3347 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
3348 // Then initialize to zero the non-header parts of the raw memory block:
3349 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
3350 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
3351 // After the initialize node executes, the object is ready for service:
3352 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
3353 // Suppose its body is immediately initialized as {1,2}:
3354 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3355 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3356 // mem.SLICE(#short[*]) := store2
3357 //
3358 // DETAILS:
3359 // An InitializeNode collects and isolates object initialization after
3360 // an AllocateNode and before the next possible safepoint. As a
3361 // memory barrier (MemBarNode), it keeps critical stores from drifting
3362 // down past any safepoint or any publication of the allocation.
3363 // Before this barrier, a newly-allocated object may have uninitialized bits.
3364 // After this barrier, it may be treated as a real oop, and GC is allowed.
3365 //
3366 // The semantics of the InitializeNode include an implicit zeroing of
3367 // the new object from object header to the end of the object.
3368 // (The object header and end are determined by the AllocateNode.)
3369 //
3370 // Certain stores may be added as direct inputs to the InitializeNode.
3371 // These stores must update raw memory, and they must be to addresses
3372 // derived from the raw address produced by AllocateNode, and with
3373 // a constant offset. They must be ordered by increasing offset.
3374 // The first one is at in(RawStores), the last at in(req()-1).
3375 // Unlike most memory operations, they are not linked in a chain,
3376 // but are displayed in parallel as users of the rawmem output of
3377 // the allocation.
3378 //
3379 // (See comments in InitializeNode::capture_store, which continue
3380 // the example given above.)
3381 //
3382 // When the associated Allocate is macro-expanded, the InitializeNode
3383 // may be rewritten to optimize collected stores. A ClearArrayNode
3384 // may also be created at that point to represent any required zeroing.
3385 // The InitializeNode is then marked 'complete', prohibiting further
3386 // capturing of nearby memory operations.
3387 //
3388 // During macro-expansion, all captured initializations which store
3389 // constant values of 32 bits or smaller are coalesced (if advantageous)
3390 // into larger 'tiles' 32 or 64 bits. This allows an object to be
3391 // initialized in fewer memory operations. Memory words which are
3392 // covered by neither tiles nor non-constant stores are pre-zeroed
3393 // by explicit stores of zero. (The code shape happens to do all
3394 // zeroing first, then all other stores, with both sequences occurring
3395 // in order of ascending offsets.)
3396 //
3397 // Alternatively, code may be inserted between an AllocateNode and its
3398 // InitializeNode, to perform arbitrary initialization of the new object.
3399 // E.g., the object copying intrinsics insert complex data transfers here.
3400 // The initialization must then be marked as 'complete' disable the
3401 // built-in zeroing semantics and the collection of initializing stores.
3402 //
3403 // While an InitializeNode is incomplete, reads from the memory state
3404 // produced by it are optimizable if they match the control edge and
3405 // new oop address associated with the allocation/initialization.
3406 // They return a stored value (if the offset matches) or else zero.
3407 // A write to the memory state, if it matches control and address,
3408 // and if it is to a constant offset, may be 'captured' by the
3409 // InitializeNode. It is cloned as a raw memory operation and rewired
3410 // inside the initialization, to the raw oop produced by the allocation.
3411 // Operations on addresses which are provably distinct (e.g., to
3412 // other AllocateNodes) are allowed to bypass the initialization.
3413 //
3414 // The effect of all this is to consolidate object initialization
3415 // (both arrays and non-arrays, both piecewise and bulk) into a
3416 // single location, where it can be optimized as a unit.
3417 //
3418 // Only stores with an offset less than TrackedInitializationLimit words
3419 // will be considered for capture by an InitializeNode. This puts a
3420 // reasonable limit on the complexity of optimized initializations.
3421
3422 //---------------------------InitializeNode------------------------------------
3423 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
3424 : _is_complete(Incomplete), _does_not_escape(false),
3425 MemBarNode(C, adr_type, rawoop)
3426 {
3427 init_class_id(Class_Initialize);
3428
3429 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
3430 assert(in(RawAddress) == rawoop, "proper init");
3431 // Note: allocation() can be NULL, for secondary initialization barriers
3432 }
3433
3434 // Since this node is not matched, it will be processed by the
3435 // register allocator. Declare that there are no constraints
3436 // on the allocation of the RawAddress edge.
3437 const RegMask &InitializeNode::in_RegMask(uint idx) const {
3438 // This edge should be set to top, by the set_complete. But be conservative.
3439 if (idx == InitializeNode::RawAddress)
3440 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
3441 return RegMask::Empty;
3442 }
3443
3444 Node* InitializeNode::memory(uint alias_idx) {
3445 Node* mem = in(Memory);
3446 if (mem->is_MergeMem()) {
3447 return mem->as_MergeMem()->memory_at(alias_idx);
3448 } else {
3449 // incoming raw memory is not split
3450 return mem;
3451 }
3452 }
3453
3454 bool InitializeNode::is_non_zero() {
3455 if (is_complete()) return false;
3456 remove_extra_zeroes();
3457 return (req() > RawStores);
3458 }
3459
3460 void InitializeNode::set_complete(PhaseGVN* phase) {
3461 assert(!is_complete(), "caller responsibility");
3462 _is_complete = Complete;
3463
3464 // After this node is complete, it contains a bunch of
3465 // raw-memory initializations. There is no need for
3466 // it to have anything to do with non-raw memory effects.
3467 // Therefore, tell all non-raw users to re-optimize themselves,
3468 // after skipping the memory effects of this initialization.
3469 PhaseIterGVN* igvn = phase->is_IterGVN();
3470 if (igvn) igvn->add_users_to_worklist(this);
3471 }
3472
3473 // convenience function
3474 // return false if the init contains any stores already
3475 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
3476 InitializeNode* init = initialization();
3477 if (init == NULL || init->is_complete()) return false;
3478 init->remove_extra_zeroes();
3479 // for now, if this allocation has already collected any inits, bail:
3480 if (init->is_non_zero()) return false;
3481 init->set_complete(phase);
3482 return true;
3483 }
3484
3485 void InitializeNode::remove_extra_zeroes() {
3486 if (req() == RawStores) return;
3487 Node* zmem = zero_memory();
3488 uint fill = RawStores;
3489 for (uint i = fill; i < req(); i++) {
3490 Node* n = in(i);
3491 if (n->is_top() || n == zmem) continue; // skip
3492 if (fill < i) set_req(fill, n); // compact
3493 ++fill;
3494 }
3495 // delete any empty spaces created:
3496 while (fill < req()) {
3497 del_req(fill);
3498 }
3499 }
3500
3501 // Helper for remembering which stores go with which offsets.
3502 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) {
3503 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
3504 intptr_t offset = -1;
3505 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
3506 phase, offset);
3507 if (base == NULL) return -1; // something is dead,
3508 if (offset < 0) return -1; // dead, dead
3509 return offset;
3510 }
3511
3512 // Helper for proving that an initialization expression is
3513 // "simple enough" to be folded into an object initialization.
3514 // Attempts to prove that a store's initial value 'n' can be captured
3515 // within the initialization without creating a vicious cycle, such as:
3516 // { Foo p = new Foo(); p.next = p; }
3517 // True for constants and parameters and small combinations thereof.
3518 bool InitializeNode::detect_init_independence(Node* n, int& count) {
3519 if (n == NULL) return true; // (can this really happen?)
3520 if (n->is_Proj()) n = n->in(0);
3521 if (n == this) return false; // found a cycle
3522 if (n->is_Con()) return true;
3523 if (n->is_Start()) return true; // params, etc., are OK
3524 if (n->is_Root()) return true; // even better
3525
3526 Node* ctl = n->in(0);
3527 if (ctl != NULL && !ctl->is_top()) {
3528 if (ctl->is_Proj()) ctl = ctl->in(0);
3529 if (ctl == this) return false;
3530
3531 // If we already know that the enclosing memory op is pinned right after
3532 // the init, then any control flow that the store has picked up
3533 // must have preceded the init, or else be equal to the init.
3534 // Even after loop optimizations (which might change control edges)
3535 // a store is never pinned *before* the availability of its inputs.
3536 if (!MemNode::all_controls_dominate(n, this))
3537 return false; // failed to prove a good control
3538 }
3539
3540 // Check data edges for possible dependencies on 'this'.
3541 if ((count += 1) > 20) return false; // complexity limit
3542 for (uint i = 1; i < n->req(); i++) {
3543 Node* m = n->in(i);
3544 if (m == NULL || m == n || m->is_top()) continue;
3545 uint first_i = n->find_edge(m);
3546 if (i != first_i) continue; // process duplicate edge just once
3547 if (!detect_init_independence(m, count)) {
3548 return false;
3549 }
3550 }
3551
3552 return true;
3553 }
3554
3555 // Here are all the checks a Store must pass before it can be moved into
3556 // an initialization. Returns zero if a check fails.
3557 // On success, returns the (constant) offset to which the store applies,
3558 // within the initialized memory.
3559 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase, bool can_reshape) {
3560 const int FAIL = 0;
3561 if (st->req() != MemNode::ValueIn + 1)
3562 return FAIL; // an inscrutable StoreNode (card mark?)
3563 Node* ctl = st->in(MemNode::Control);
3564 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this))
3565 return FAIL; // must be unconditional after the initialization
3566 Node* mem = st->in(MemNode::Memory);
3567 if (!(mem->is_Proj() && mem->in(0) == this))
3568 return FAIL; // must not be preceded by other stores
3569 Node* adr = st->in(MemNode::Address);
3570 intptr_t offset;
3571 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
3572 if (alloc == NULL)
3573 return FAIL; // inscrutable address
3574 if (alloc != allocation())
3575 return FAIL; // wrong allocation! (store needs to float up)
3576 int size_in_bytes = st->memory_size();
3577 if ((size_in_bytes != 0) && (offset % size_in_bytes) != 0) {
3578 return FAIL; // mismatched access
3579 }
3580 Node* val = st->in(MemNode::ValueIn);
3581 int complexity_count = 0;
3582 if (!detect_init_independence(val, complexity_count))
3583 return FAIL; // stored value must be 'simple enough'
3584
3585 // The Store can be captured only if nothing after the allocation
3586 // and before the Store is using the memory location that the store
3587 // overwrites.
3588 bool failed = false;
3589 // If is_complete_with_arraycopy() is true the shape of the graph is
3590 // well defined and is safe so no need for extra checks.
3591 if (!is_complete_with_arraycopy()) {
3592 // We are going to look at each use of the memory state following
3593 // the allocation to make sure nothing reads the memory that the
3594 // Store writes.
3595 const TypePtr* t_adr = phase->type(adr)->isa_ptr();
3596 int alias_idx = phase->C->get_alias_index(t_adr);
3597 ResourceMark rm;
3598 Unique_Node_List mems;
3599 mems.push(mem);
3600 Node* unique_merge = NULL;
3601 for (uint next = 0; next < mems.size(); ++next) {
3602 Node *m = mems.at(next);
3603 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
3604 Node *n = m->fast_out(j);
3605 if (n->outcnt() == 0) {
3606 continue;
3607 }
3608 if (n == st) {
3609 continue;
3610 } else if (n->in(0) != NULL && n->in(0) != ctl) {
3611 // If the control of this use is different from the control
3612 // of the Store which is right after the InitializeNode then
3613 // this node cannot be between the InitializeNode and the
3614 // Store.
3615 continue;
3616 } else if (n->is_MergeMem()) {
3617 if (n->as_MergeMem()->memory_at(alias_idx) == m) {
3618 // We can hit a MergeMemNode (that will likely go away
3619 // later) that is a direct use of the memory state
3620 // following the InitializeNode on the same slice as the
3621 // store node that we'd like to capture. We need to check
3622 // the uses of the MergeMemNode.
3623 mems.push(n);
3624 }
3625 } else if (n->is_Mem()) {
3626 Node* other_adr = n->in(MemNode::Address);
3627 if (other_adr == adr) {
3628 failed = true;
3629 break;
3630 } else {
3631 const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr();
3632 if (other_t_adr != NULL) {
3633 int other_alias_idx = phase->C->get_alias_index(other_t_adr);
3634 if (other_alias_idx == alias_idx) {
3635 // A load from the same memory slice as the store right
3636 // after the InitializeNode. We check the control of the
3637 // object/array that is loaded from. If it's the same as
3638 // the store control then we cannot capture the store.
3639 assert(!n->is_Store(), "2 stores to same slice on same control?");
3640 Node* base = other_adr;
3641 assert(base->is_AddP(), "should be addp but is %s", base->Name());
3642 base = base->in(AddPNode::Base);
3643 if (base != NULL) {
3644 base = base->uncast();
3645 if (base->is_Proj() && base->in(0) == alloc) {
3646 failed = true;
3647 break;
3648 }
3649 }
3650 }
3651 }
3652 }
3653 } else {
3654 failed = true;
3655 break;
3656 }
3657 }
3658 }
3659 }
3660 if (failed) {
3661 if (!can_reshape) {
3662 // We decided we couldn't capture the store during parsing. We
3663 // should try again during the next IGVN once the graph is
3664 // cleaner.
3665 phase->C->record_for_igvn(st);
3666 }
3667 return FAIL;
3668 }
3669
3670 return offset; // success
3671 }
3672
3673 // Find the captured store in(i) which corresponds to the range
3674 // [start..start+size) in the initialized object.
3675 // If there is one, return its index i. If there isn't, return the
3676 // negative of the index where it should be inserted.
3677 // Return 0 if the queried range overlaps an initialization boundary
3678 // or if dead code is encountered.
3679 // If size_in_bytes is zero, do not bother with overlap checks.
3680 int InitializeNode::captured_store_insertion_point(intptr_t start,
3681 int size_in_bytes,
3682 PhaseTransform* phase) {
3683 const int FAIL = 0, MAX_STORE = BytesPerLong;
3684
3685 if (is_complete())
3686 return FAIL; // arraycopy got here first; punt
3687
3688 assert(allocation() != NULL, "must be present");
3689
3690 // no negatives, no header fields:
3691 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
3692
3693 // after a certain size, we bail out on tracking all the stores:
3694 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3695 if (start >= ti_limit) return FAIL;
3696
3697 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
3698 if (i >= limit) return -(int)i; // not found; here is where to put it
3699
3700 Node* st = in(i);
3701 intptr_t st_off = get_store_offset(st, phase);
3702 if (st_off < 0) {
3703 if (st != zero_memory()) {
3704 return FAIL; // bail out if there is dead garbage
3705 }
3706 } else if (st_off > start) {
3707 // ...we are done, since stores are ordered
3708 if (st_off < start + size_in_bytes) {
3709 return FAIL; // the next store overlaps
3710 }
3711 return -(int)i; // not found; here is where to put it
3712 } else if (st_off < start) {
3713 if (size_in_bytes != 0 &&
3714 start < st_off + MAX_STORE &&
3715 start < st_off + st->as_Store()->memory_size()) {
3716 return FAIL; // the previous store overlaps
3717 }
3718 } else {
3719 if (size_in_bytes != 0 &&
3720 st->as_Store()->memory_size() != size_in_bytes) {
3721 return FAIL; // mismatched store size
3722 }
3723 return i;
3724 }
3725
3726 ++i;
3727 }
3728 }
3729
3730 // Look for a captured store which initializes at the offset 'start'
3731 // with the given size. If there is no such store, and no other
3732 // initialization interferes, then return zero_memory (the memory
3733 // projection of the AllocateNode).
3734 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
3735 PhaseTransform* phase) {
3736 assert(stores_are_sane(phase), "");
3737 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3738 if (i == 0) {
3739 return NULL; // something is dead
3740 } else if (i < 0) {
3741 return zero_memory(); // just primordial zero bits here
3742 } else {
3743 Node* st = in(i); // here is the store at this position
3744 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
3745 return st;
3746 }
3747 }
3748
3749 // Create, as a raw pointer, an address within my new object at 'offset'.
3750 Node* InitializeNode::make_raw_address(intptr_t offset,
3751 PhaseTransform* phase) {
3752 Node* addr = in(RawAddress);
3753 if (offset != 0) {
3754 Compile* C = phase->C;
3755 addr = phase->transform( new AddPNode(C->top(), addr,
3756 phase->MakeConX(offset)) );
3757 }
3758 return addr;
3759 }
3760
3761 // Clone the given store, converting it into a raw store
3762 // initializing a field or element of my new object.
3763 // Caller is responsible for retiring the original store,
3764 // with subsume_node or the like.
3765 //
3766 // From the example above InitializeNode::InitializeNode,
3767 // here are the old stores to be captured:
3768 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3769 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3770 //
3771 // Here is the changed code; note the extra edges on init:
3772 // alloc = (Allocate ...)
3773 // rawoop = alloc.RawAddress
3774 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
3775 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
3776 // init = (Initialize alloc.Control alloc.Memory rawoop
3777 // rawstore1 rawstore2)
3778 //
3779 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
3780 PhaseTransform* phase, bool can_reshape) {
3781 assert(stores_are_sane(phase), "");
3782
3783 if (start < 0) return NULL;
3784 assert(can_capture_store(st, phase, can_reshape) == start, "sanity");
3785
3786 Compile* C = phase->C;
3787 int size_in_bytes = st->memory_size();
3788 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3789 if (i == 0) return NULL; // bail out
3790 Node* prev_mem = NULL; // raw memory for the captured store
3791 if (i > 0) {
3792 prev_mem = in(i); // there is a pre-existing store under this one
3793 set_req(i, C->top()); // temporarily disconnect it
3794 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
3795 } else {
3796 i = -i; // no pre-existing store
3797 prev_mem = zero_memory(); // a slice of the newly allocated object
3798 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
3799 set_req(--i, C->top()); // reuse this edge; it has been folded away
3800 else
3801 ins_req(i, C->top()); // build a new edge
3802 }
3803 Node* new_st = st->clone();
3804 new_st->set_req(MemNode::Control, in(Control));
3805 new_st->set_req(MemNode::Memory, prev_mem);
3806 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
3807 new_st = phase->transform(new_st);
3808
3809 // At this point, new_st might have swallowed a pre-existing store
3810 // at the same offset, or perhaps new_st might have disappeared,
3811 // if it redundantly stored the same value (or zero to fresh memory).
3812
3813 // In any case, wire it in:
3814 phase->igvn_rehash_node_delayed(this);
3815 set_req(i, new_st);
3816
3817 // The caller may now kill the old guy.
3818 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
3819 assert(check_st == new_st || check_st == NULL, "must be findable");
3820 assert(!is_complete(), "");
3821 return new_st;
3822 }
3823
3824 static bool store_constant(jlong* tiles, int num_tiles,
3825 intptr_t st_off, int st_size,
3826 jlong con) {
3827 if ((st_off & (st_size-1)) != 0)
3828 return false; // strange store offset (assume size==2**N)
3829 address addr = (address)tiles + st_off;
3830 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
3831 switch (st_size) {
3832 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
3833 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
3834 case sizeof(jint): *(jint*) addr = (jint) con; break;
3835 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
3836 default: return false; // strange store size (detect size!=2**N here)
3837 }
3838 return true; // return success to caller
3839 }
3840
3841 // Coalesce subword constants into int constants and possibly
3842 // into long constants. The goal, if the CPU permits,
3843 // is to initialize the object with a small number of 64-bit tiles.
3844 // Also, convert floating-point constants to bit patterns.
3845 // Non-constants are not relevant to this pass.
3846 //
3847 // In terms of the running example on InitializeNode::InitializeNode
3848 // and InitializeNode::capture_store, here is the transformation
3849 // of rawstore1 and rawstore2 into rawstore12:
3850 // alloc = (Allocate ...)
3851 // rawoop = alloc.RawAddress
3852 // tile12 = 0x00010002
3853 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
3854 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
3855 //
3856 void
3857 InitializeNode::coalesce_subword_stores(intptr_t header_size,
3858 Node* size_in_bytes,
3859 PhaseGVN* phase) {
3860 Compile* C = phase->C;
3861
3862 assert(stores_are_sane(phase), "");
3863 // Note: After this pass, they are not completely sane,
3864 // since there may be some overlaps.
3865
3866 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
3867
3868 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3869 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
3870 size_limit = MIN2(size_limit, ti_limit);
3871 size_limit = align_up(size_limit, BytesPerLong);
3872 int num_tiles = size_limit / BytesPerLong;
3873
3874 // allocate space for the tile map:
3875 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
3876 jlong tiles_buf[small_len];
3877 Node* nodes_buf[small_len];
3878 jlong inits_buf[small_len];
3879 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
3880 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3881 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
3882 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
3883 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
3884 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3885 // tiles: exact bitwise model of all primitive constants
3886 // nodes: last constant-storing node subsumed into the tiles model
3887 // inits: which bytes (in each tile) are touched by any initializations
3888
3889 //// Pass A: Fill in the tile model with any relevant stores.
3890
3891 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
3892 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
3893 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
3894 Node* zmem = zero_memory(); // initially zero memory state
3895 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3896 Node* st = in(i);
3897 intptr_t st_off = get_store_offset(st, phase);
3898
3899 // Figure out the store's offset and constant value:
3900 if (st_off < header_size) continue; //skip (ignore header)
3901 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
3902 int st_size = st->as_Store()->memory_size();
3903 if (st_off + st_size > size_limit) break;
3904
3905 // Record which bytes are touched, whether by constant or not.
3906 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
3907 continue; // skip (strange store size)
3908
3909 const Type* val = phase->type(st->in(MemNode::ValueIn));
3910 if (!val->singleton()) continue; //skip (non-con store)
3911 BasicType type = val->basic_type();
3912
3913 jlong con = 0;
3914 switch (type) {
3915 case T_INT: con = val->is_int()->get_con(); break;
3916 case T_LONG: con = val->is_long()->get_con(); break;
3917 case T_FLOAT: con = jint_cast(val->getf()); break;
3918 case T_DOUBLE: con = jlong_cast(val->getd()); break;
3919 default: continue; //skip (odd store type)
3920 }
3921
3922 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
3923 st->Opcode() == Op_StoreL) {
3924 continue; // This StoreL is already optimal.
3925 }
3926
3927 // Store down the constant.
3928 store_constant(tiles, num_tiles, st_off, st_size, con);
3929
3930 intptr_t j = st_off >> LogBytesPerLong;
3931
3932 if (type == T_INT && st_size == BytesPerInt
3933 && (st_off & BytesPerInt) == BytesPerInt) {
3934 jlong lcon = tiles[j];
3935 if (!Matcher::isSimpleConstant64(lcon) &&
3936 st->Opcode() == Op_StoreI) {
3937 // This StoreI is already optimal by itself.
3938 jint* intcon = (jint*) &tiles[j];
3939 intcon[1] = 0; // undo the store_constant()
3940
3941 // If the previous store is also optimal by itself, back up and
3942 // undo the action of the previous loop iteration... if we can.
3943 // But if we can't, just let the previous half take care of itself.
3944 st = nodes[j];
3945 st_off -= BytesPerInt;
3946 con = intcon[0];
3947 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) {
3948 assert(st_off >= header_size, "still ignoring header");
3949 assert(get_store_offset(st, phase) == st_off, "must be");
3950 assert(in(i-1) == zmem, "must be");
3951 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
3952 assert(con == tcon->is_int()->get_con(), "must be");
3953 // Undo the effects of the previous loop trip, which swallowed st:
3954 intcon[0] = 0; // undo store_constant()
3955 set_req(i-1, st); // undo set_req(i, zmem)
3956 nodes[j] = NULL; // undo nodes[j] = st
3957 --old_subword; // undo ++old_subword
3958 }
3959 continue; // This StoreI is already optimal.
3960 }
3961 }
3962
3963 // This store is not needed.
3964 set_req(i, zmem);
3965 nodes[j] = st; // record for the moment
3966 if (st_size < BytesPerLong) // something has changed
3967 ++old_subword; // includes int/float, but who's counting...
3968 else ++old_long;
3969 }
3970
3971 if ((old_subword + old_long) == 0)
3972 return; // nothing more to do
3973
3974 //// Pass B: Convert any non-zero tiles into optimal constant stores.
3975 // Be sure to insert them before overlapping non-constant stores.
3976 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
3977 for (int j = 0; j < num_tiles; j++) {
3978 jlong con = tiles[j];
3979 jlong init = inits[j];
3980 if (con == 0) continue;
3981 jint con0, con1; // split the constant, address-wise
3982 jint init0, init1; // split the init map, address-wise
3983 { union { jlong con; jint intcon[2]; } u;
3984 u.con = con;
3985 con0 = u.intcon[0];
3986 con1 = u.intcon[1];
3987 u.con = init;
3988 init0 = u.intcon[0];
3989 init1 = u.intcon[1];
3990 }
3991
3992 Node* old = nodes[j];
3993 assert(old != NULL, "need the prior store");
3994 intptr_t offset = (j * BytesPerLong);
3995
3996 bool split = !Matcher::isSimpleConstant64(con);
3997
3998 if (offset < header_size) {
3999 assert(offset + BytesPerInt >= header_size, "second int counts");
4000 assert(*(jint*)&tiles[j] == 0, "junk in header");
4001 split = true; // only the second word counts
4002 // Example: int a[] = { 42 ... }
4003 } else if (con0 == 0 && init0 == -1) {
4004 split = true; // first word is covered by full inits
4005 // Example: int a[] = { ... foo(), 42 ... }
4006 } else if (con1 == 0 && init1 == -1) {
4007 split = true; // second word is covered by full inits
4008 // Example: int a[] = { ... 42, foo() ... }
4009 }
4010
4011 // Here's a case where init0 is neither 0 nor -1:
4012 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
4013 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
4014 // In this case the tile is not split; it is (jlong)42.
4015 // The big tile is stored down, and then the foo() value is inserted.
4016 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
4017
4018 Node* ctl = old->in(MemNode::Control);
4019 Node* adr = make_raw_address(offset, phase);
4020 const TypePtr* atp = TypeRawPtr::BOTTOM;
4021
4022 // One or two coalesced stores to plop down.
4023 Node* st[2];
4024 intptr_t off[2];
4025 int nst = 0;
4026 if (!split) {
4027 ++new_long;
4028 off[nst] = offset;
4029 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
4030 phase->longcon(con), T_LONG, MemNode::unordered);
4031 } else {
4032 // Omit either if it is a zero.
4033 if (con0 != 0) {
4034 ++new_int;
4035 off[nst] = offset;
4036 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
4037 phase->intcon(con0), T_INT, MemNode::unordered);
4038 }
4039 if (con1 != 0) {
4040 ++new_int;
4041 offset += BytesPerInt;
4042 adr = make_raw_address(offset, phase);
4043 off[nst] = offset;
4044 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
4045 phase->intcon(con1), T_INT, MemNode::unordered);
4046 }
4047 }
4048
4049 // Insert second store first, then the first before the second.
4050 // Insert each one just before any overlapping non-constant stores.
4051 while (nst > 0) {
4052 Node* st1 = st[--nst];
4053 C->copy_node_notes_to(st1, old);
4054 st1 = phase->transform(st1);
4055 offset = off[nst];
4056 assert(offset >= header_size, "do not smash header");
4057 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
4058 guarantee(ins_idx != 0, "must re-insert constant store");
4059 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
4060 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
4061 set_req(--ins_idx, st1);
4062 else
4063 ins_req(ins_idx, st1);
4064 }
4065 }
4066
4067 if (PrintCompilation && WizardMode)
4068 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
4069 old_subword, old_long, new_int, new_long);
4070 if (C->log() != NULL)
4071 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
4072 old_subword, old_long, new_int, new_long);
4073
4074 // Clean up any remaining occurrences of zmem:
4075 remove_extra_zeroes();
4076 }
4077
4078 // Explore forward from in(start) to find the first fully initialized
4079 // word, and return its offset. Skip groups of subword stores which
4080 // together initialize full words. If in(start) is itself part of a
4081 // fully initialized word, return the offset of in(start). If there
4082 // are no following full-word stores, or if something is fishy, return
4083 // a negative value.
4084 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
4085 int int_map = 0;
4086 intptr_t int_map_off = 0;
4087 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
4088
4089 for (uint i = start, limit = req(); i < limit; i++) {
4090 Node* st = in(i);
4091
4092 intptr_t st_off = get_store_offset(st, phase);
4093 if (st_off < 0) break; // return conservative answer
4094
4095 int st_size = st->as_Store()->memory_size();
4096 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
4097 return st_off; // we found a complete word init
4098 }
4099
4100 // update the map:
4101
4102 intptr_t this_int_off = align_down(st_off, BytesPerInt);
4103 if (this_int_off != int_map_off) {
4104 // reset the map:
4105 int_map = 0;
4106 int_map_off = this_int_off;
4107 }
4108
4109 int subword_off = st_off - this_int_off;
4110 int_map |= right_n_bits(st_size) << subword_off;
4111 if ((int_map & FULL_MAP) == FULL_MAP) {
4112 return this_int_off; // we found a complete word init
4113 }
4114
4115 // Did this store hit or cross the word boundary?
4116 intptr_t next_int_off = align_down(st_off + st_size, BytesPerInt);
4117 if (next_int_off == this_int_off + BytesPerInt) {
4118 // We passed the current int, without fully initializing it.
4119 int_map_off = next_int_off;
4120 int_map >>= BytesPerInt;
4121 } else if (next_int_off > this_int_off + BytesPerInt) {
4122 // We passed the current and next int.
4123 return this_int_off + BytesPerInt;
4124 }
4125 }
4126
4127 return -1;
4128 }
4129
4130
4131 // Called when the associated AllocateNode is expanded into CFG.
4132 // At this point, we may perform additional optimizations.
4133 // Linearize the stores by ascending offset, to make memory
4134 // activity as coherent as possible.
4135 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
4136 intptr_t header_size,
4137 Node* size_in_bytes,
4138 PhaseGVN* phase) {
4139 assert(!is_complete(), "not already complete");
4140 assert(stores_are_sane(phase), "");
4141 assert(allocation() != NULL, "must be present");
4142
4143 remove_extra_zeroes();
4144
4145 if (ReduceFieldZeroing || ReduceBulkZeroing)
4146 // reduce instruction count for common initialization patterns
4147 coalesce_subword_stores(header_size, size_in_bytes, phase);
4148
4149 Node* zmem = zero_memory(); // initially zero memory state
4150 Node* inits = zmem; // accumulating a linearized chain of inits
4151 #ifdef ASSERT
4152 intptr_t first_offset = allocation()->minimum_header_size();
4153 intptr_t last_init_off = first_offset; // previous init offset
4154 intptr_t last_init_end = first_offset; // previous init offset+size
4155 intptr_t last_tile_end = first_offset; // previous tile offset+size
4156 #endif
4157 intptr_t zeroes_done = header_size;
4158
4159 bool do_zeroing = true; // we might give up if inits are very sparse
4160 int big_init_gaps = 0; // how many large gaps have we seen?
4161
4162 if (UseTLAB && ZeroTLAB) do_zeroing = false;
4163 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
4164
4165 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
4166 Node* st = in(i);
4167 intptr_t st_off = get_store_offset(st, phase);
4168 if (st_off < 0)
4169 break; // unknown junk in the inits
4170 if (st->in(MemNode::Memory) != zmem)
4171 break; // complicated store chains somehow in list
4172
4173 int st_size = st->as_Store()->memory_size();
4174 intptr_t next_init_off = st_off + st_size;
4175
4176 if (do_zeroing && zeroes_done < next_init_off) {
4177 // See if this store needs a zero before it or under it.
4178 intptr_t zeroes_needed = st_off;
4179
4180 if (st_size < BytesPerInt) {
4181 // Look for subword stores which only partially initialize words.
4182 // If we find some, we must lay down some word-level zeroes first,
4183 // underneath the subword stores.
4184 //
4185 // Examples:
4186 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
4187 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
4188 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
4189 //
4190 // Note: coalesce_subword_stores may have already done this,
4191 // if it was prompted by constant non-zero subword initializers.
4192 // But this case can still arise with non-constant stores.
4193
4194 intptr_t next_full_store = find_next_fullword_store(i, phase);
4195
4196 // In the examples above:
4197 // in(i) p q r s x y z
4198 // st_off 12 13 14 15 12 13 14
4199 // st_size 1 1 1 1 1 1 1
4200 // next_full_s. 12 16 16 16 16 16 16
4201 // z's_done 12 16 16 16 12 16 12
4202 // z's_needed 12 16 16 16 16 16 16
4203 // zsize 0 0 0 0 4 0 4
4204 if (next_full_store < 0) {
4205 // Conservative tack: Zero to end of current word.
4206 zeroes_needed = align_up(zeroes_needed, BytesPerInt);
4207 } else {
4208 // Zero to beginning of next fully initialized word.
4209 // Or, don't zero at all, if we are already in that word.
4210 assert(next_full_store >= zeroes_needed, "must go forward");
4211 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
4212 zeroes_needed = next_full_store;
4213 }
4214 }
4215
4216 if (zeroes_needed > zeroes_done) {
4217 intptr_t zsize = zeroes_needed - zeroes_done;
4218 // Do some incremental zeroing on rawmem, in parallel with inits.
4219 zeroes_done = align_down(zeroes_done, BytesPerInt);
4220 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
4221 zeroes_done, zeroes_needed,
4222 phase);
4223 zeroes_done = zeroes_needed;
4224 if (zsize > InitArrayShortSize && ++big_init_gaps > 2)
4225 do_zeroing = false; // leave the hole, next time
4226 }
4227 }
4228
4229 // Collect the store and move on:
4230 st->set_req(MemNode::Memory, inits);
4231 inits = st; // put it on the linearized chain
4232 set_req(i, zmem); // unhook from previous position
4233
4234 if (zeroes_done == st_off)
4235 zeroes_done = next_init_off;
4236
4237 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
4238
4239 #ifdef ASSERT
4240 // Various order invariants. Weaker than stores_are_sane because
4241 // a large constant tile can be filled in by smaller non-constant stores.
4242 assert(st_off >= last_init_off, "inits do not reverse");
4243 last_init_off = st_off;
4244 const Type* val = NULL;
4245 if (st_size >= BytesPerInt &&
4246 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
4247 (int)val->basic_type() < (int)T_OBJECT) {
4248 assert(st_off >= last_tile_end, "tiles do not overlap");
4249 assert(st_off >= last_init_end, "tiles do not overwrite inits");
4250 last_tile_end = MAX2(last_tile_end, next_init_off);
4251 } else {
4252 intptr_t st_tile_end = align_up(next_init_off, BytesPerLong);
4253 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
4254 assert(st_off >= last_init_end, "inits do not overlap");
4255 last_init_end = next_init_off; // it's a non-tile
4256 }
4257 #endif //ASSERT
4258 }
4259
4260 remove_extra_zeroes(); // clear out all the zmems left over
4261 add_req(inits);
4262
4263 if (!(UseTLAB && ZeroTLAB)) {
4264 // If anything remains to be zeroed, zero it all now.
4265 zeroes_done = align_down(zeroes_done, BytesPerInt);
4266 // if it is the last unused 4 bytes of an instance, forget about it
4267 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
4268 if (zeroes_done + BytesPerLong >= size_limit) {
4269 AllocateNode* alloc = allocation();
4270 assert(alloc != NULL, "must be present");
4271 if (alloc != NULL && alloc->Opcode() == Op_Allocate) {
4272 Node* klass_node = alloc->in(AllocateNode::KlassNode);
4273 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass();
4274 if (zeroes_done == k->layout_helper())
4275 zeroes_done = size_limit;
4276 }
4277 }
4278 if (zeroes_done < size_limit) {
4279 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
4280 zeroes_done, size_in_bytes, phase);
4281 }
4282 }
4283
4284 set_complete(phase);
4285 return rawmem;
4286 }
4287
4288
4289 #ifdef ASSERT
4290 bool InitializeNode::stores_are_sane(PhaseTransform* phase) {
4291 if (is_complete())
4292 return true; // stores could be anything at this point
4293 assert(allocation() != NULL, "must be present");
4294 intptr_t last_off = allocation()->minimum_header_size();
4295 for (uint i = InitializeNode::RawStores; i < req(); i++) {
4296 Node* st = in(i);
4297 intptr_t st_off = get_store_offset(st, phase);
4298 if (st_off < 0) continue; // ignore dead garbage
4299 if (last_off > st_off) {
4300 tty->print_cr("*** bad store offset at %d: " INTX_FORMAT " > " INTX_FORMAT, i, last_off, st_off);
4301 this->dump(2);
4302 assert(false, "ascending store offsets");
4303 return false;
4304 }
4305 last_off = st_off + st->as_Store()->memory_size();
4306 }
4307 return true;
4308 }
4309 #endif //ASSERT
4310
4311
4312
4313
4314 //============================MergeMemNode=====================================
4315 //
4316 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
4317 // contributing store or call operations. Each contributor provides the memory
4318 // state for a particular "alias type" (see Compile::alias_type). For example,
4319 // if a MergeMem has an input X for alias category #6, then any memory reference
4320 // to alias category #6 may use X as its memory state input, as an exact equivalent
4321 // to using the MergeMem as a whole.
4322 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
4323 //
4324 // (Here, the <N> notation gives the index of the relevant adr_type.)
4325 //
4326 // In one special case (and more cases in the future), alias categories overlap.
4327 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
4328 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
4329 // it is exactly equivalent to that state W:
4330 // MergeMem(<Bot>: W) <==> W
4331 //
4332 // Usually, the merge has more than one input. In that case, where inputs
4333 // overlap (i.e., one is Bot), the narrower alias type determines the memory
4334 // state for that type, and the wider alias type (Bot) fills in everywhere else:
4335 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
4336 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
4337 //
4338 // A merge can take a "wide" memory state as one of its narrow inputs.
4339 // This simply means that the merge observes out only the relevant parts of
4340 // the wide input. That is, wide memory states arriving at narrow merge inputs
4341 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
4342 //
4343 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
4344 // and that memory slices "leak through":
4345 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
4346 //
4347 // But, in such a cascade, repeated memory slices can "block the leak":
4348 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
4349 //
4350 // In the last example, Y is not part of the combined memory state of the
4351 // outermost MergeMem. The system must, of course, prevent unschedulable
4352 // memory states from arising, so you can be sure that the state Y is somehow
4353 // a precursor to state Y'.
4354 //
4355 //
4356 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
4357 // of each MergeMemNode array are exactly the numerical alias indexes, including
4358 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
4359 // Compile::alias_type (and kin) produce and manage these indexes.
4360 //
4361 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
4362 // (Note that this provides quick access to the top node inside MergeMem methods,
4363 // without the need to reach out via TLS to Compile::current.)
4364 //
4365 // As a consequence of what was just described, a MergeMem that represents a full
4366 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
4367 // containing all alias categories.
4368 //
4369 // MergeMem nodes never (?) have control inputs, so in(0) is NULL.
4370 //
4371 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
4372 // a memory state for the alias type <N>, or else the top node, meaning that
4373 // there is no particular input for that alias type. Note that the length of
4374 // a MergeMem is variable, and may be extended at any time to accommodate new
4375 // memory states at larger alias indexes. When merges grow, they are of course
4376 // filled with "top" in the unused in() positions.
4377 //
4378 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
4379 // (Top was chosen because it works smoothly with passes like GCM.)
4380 //
4381 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
4382 // the type of random VM bits like TLS references.) Since it is always the
4383 // first non-Bot memory slice, some low-level loops use it to initialize an
4384 // index variable: for (i = AliasIdxRaw; i < req(); i++).
4385 //
4386 //
4387 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
4388 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
4389 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
4390 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
4391 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
4392 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
4393 //
4394 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
4395 // really that different from the other memory inputs. An abbreviation called
4396 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
4397 //
4398 //
4399 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
4400 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
4401 // that "emerges though" the base memory will be marked as excluding the alias types
4402 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
4403 //
4404 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
4405 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
4406 //
4407 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
4408 // (It is currently unimplemented.) As you can see, the resulting merge is
4409 // actually a disjoint union of memory states, rather than an overlay.
4410 //
4411
4412 //------------------------------MergeMemNode-----------------------------------
4413 Node* MergeMemNode::make_empty_memory() {
4414 Node* empty_memory = (Node*) Compile::current()->top();
4415 assert(empty_memory->is_top(), "correct sentinel identity");
4416 return empty_memory;
4417 }
4418
4419 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
4420 init_class_id(Class_MergeMem);
4421 // all inputs are nullified in Node::Node(int)
4422 // set_input(0, NULL); // no control input
4423
4424 // Initialize the edges uniformly to top, for starters.
4425 Node* empty_mem = make_empty_memory();
4426 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
4427 init_req(i,empty_mem);
4428 }
4429 assert(empty_memory() == empty_mem, "");
4430
4431 if( new_base != NULL && new_base->is_MergeMem() ) {
4432 MergeMemNode* mdef = new_base->as_MergeMem();
4433 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
4434 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
4435 mms.set_memory(mms.memory2());
4436 }
4437 assert(base_memory() == mdef->base_memory(), "");
4438 } else {
4439 set_base_memory(new_base);
4440 }
4441 }
4442
4443 // Make a new, untransformed MergeMem with the same base as 'mem'.
4444 // If mem is itself a MergeMem, populate the result with the same edges.
4445 MergeMemNode* MergeMemNode::make(Node* mem) {
4446 return new MergeMemNode(mem);
4447 }
4448
4449 //------------------------------cmp--------------------------------------------
4450 uint MergeMemNode::hash() const { return NO_HASH; }
4451 uint MergeMemNode::cmp( const Node &n ) const {
4452 return (&n == this); // Always fail except on self
4453 }
4454
4455 //------------------------------Identity---------------------------------------
4456 Node* MergeMemNode::Identity(PhaseGVN* phase) {
4457 // Identity if this merge point does not record any interesting memory
4458 // disambiguations.
4459 Node* base_mem = base_memory();
4460 Node* empty_mem = empty_memory();
4461 if (base_mem != empty_mem) { // Memory path is not dead?
4462 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4463 Node* mem = in(i);
4464 if (mem != empty_mem && mem != base_mem) {
4465 return this; // Many memory splits; no change
4466 }
4467 }
4468 }
4469 return base_mem; // No memory splits; ID on the one true input
4470 }
4471
4472 //------------------------------Ideal------------------------------------------
4473 // This method is invoked recursively on chains of MergeMem nodes
4474 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4475 // Remove chain'd MergeMems
4476 //
4477 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
4478 // relative to the "in(Bot)". Since we are patching both at the same time,
4479 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
4480 // but rewrite each "in(i)" relative to the new "in(Bot)".
4481 Node *progress = NULL;
4482
4483
4484 Node* old_base = base_memory();
4485 Node* empty_mem = empty_memory();
4486 if (old_base == empty_mem)
4487 return NULL; // Dead memory path.
4488
4489 MergeMemNode* old_mbase;
4490 if (old_base != NULL && old_base->is_MergeMem())
4491 old_mbase = old_base->as_MergeMem();
4492 else
4493 old_mbase = NULL;
4494 Node* new_base = old_base;
4495
4496 // simplify stacked MergeMems in base memory
4497 if (old_mbase) new_base = old_mbase->base_memory();
4498
4499 // the base memory might contribute new slices beyond my req()
4500 if (old_mbase) grow_to_match(old_mbase);
4501
4502 // Look carefully at the base node if it is a phi.
4503 PhiNode* phi_base;
4504 if (new_base != NULL && new_base->is_Phi())
4505 phi_base = new_base->as_Phi();
4506 else
4507 phi_base = NULL;
4508
4509 Node* phi_reg = NULL;
4510 uint phi_len = (uint)-1;
4511 if (phi_base != NULL && !phi_base->is_copy()) {
4512 // do not examine phi if degraded to a copy
4513 phi_reg = phi_base->region();
4514 phi_len = phi_base->req();
4515 // see if the phi is unfinished
4516 for (uint i = 1; i < phi_len; i++) {
4517 if (phi_base->in(i) == NULL) {
4518 // incomplete phi; do not look at it yet!
4519 phi_reg = NULL;
4520 phi_len = (uint)-1;
4521 break;
4522 }
4523 }
4524 }
4525
4526 // Note: We do not call verify_sparse on entry, because inputs
4527 // can normalize to the base_memory via subsume_node or similar
4528 // mechanisms. This method repairs that damage.
4529
4530 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
4531
4532 // Look at each slice.
4533 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4534 Node* old_in = in(i);
4535 // calculate the old memory value
4536 Node* old_mem = old_in;
4537 if (old_mem == empty_mem) old_mem = old_base;
4538 assert(old_mem == memory_at(i), "");
4539
4540 // maybe update (reslice) the old memory value
4541
4542 // simplify stacked MergeMems
4543 Node* new_mem = old_mem;
4544 MergeMemNode* old_mmem;
4545 if (old_mem != NULL && old_mem->is_MergeMem())
4546 old_mmem = old_mem->as_MergeMem();
4547 else
4548 old_mmem = NULL;
4549 if (old_mmem == this) {
4550 // This can happen if loops break up and safepoints disappear.
4551 // A merge of BotPtr (default) with a RawPtr memory derived from a
4552 // safepoint can be rewritten to a merge of the same BotPtr with
4553 // the BotPtr phi coming into the loop. If that phi disappears
4554 // also, we can end up with a self-loop of the mergemem.
4555 // In general, if loops degenerate and memory effects disappear,
4556 // a mergemem can be left looking at itself. This simply means
4557 // that the mergemem's default should be used, since there is
4558 // no longer any apparent effect on this slice.
4559 // Note: If a memory slice is a MergeMem cycle, it is unreachable
4560 // from start. Update the input to TOP.
4561 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
4562 }
4563 else if (old_mmem != NULL) {
4564 new_mem = old_mmem->memory_at(i);
4565 }
4566 // else preceding memory was not a MergeMem
4567
4568 // replace equivalent phis (unfortunately, they do not GVN together)
4569 if (new_mem != NULL && new_mem != new_base &&
4570 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) {
4571 if (new_mem->is_Phi()) {
4572 PhiNode* phi_mem = new_mem->as_Phi();
4573 for (uint i = 1; i < phi_len; i++) {
4574 if (phi_base->in(i) != phi_mem->in(i)) {
4575 phi_mem = NULL;
4576 break;
4577 }
4578 }
4579 if (phi_mem != NULL) {
4580 // equivalent phi nodes; revert to the def
4581 new_mem = new_base;
4582 }
4583 }
4584 }
4585
4586 // maybe store down a new value
4587 Node* new_in = new_mem;
4588 if (new_in == new_base) new_in = empty_mem;
4589
4590 if (new_in != old_in) {
4591 // Warning: Do not combine this "if" with the previous "if"
4592 // A memory slice might have be be rewritten even if it is semantically
4593 // unchanged, if the base_memory value has changed.
4594 set_req(i, new_in);
4595 progress = this; // Report progress
4596 }
4597 }
4598
4599 if (new_base != old_base) {
4600 set_req(Compile::AliasIdxBot, new_base);
4601 // Don't use set_base_memory(new_base), because we need to update du.
4602 assert(base_memory() == new_base, "");
4603 progress = this;
4604 }
4605
4606 if( base_memory() == this ) {
4607 // a self cycle indicates this memory path is dead
4608 set_req(Compile::AliasIdxBot, empty_mem);
4609 }
4610
4611 // Resolve external cycles by calling Ideal on a MergeMem base_memory
4612 // Recursion must occur after the self cycle check above
4613 if( base_memory()->is_MergeMem() ) {
4614 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
4615 Node *m = phase->transform(new_mbase); // Rollup any cycles
4616 if( m != NULL &&
4617 (m->is_top() ||
4618 (m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem)) ) {
4619 // propagate rollup of dead cycle to self
4620 set_req(Compile::AliasIdxBot, empty_mem);
4621 }
4622 }
4623
4624 if( base_memory() == empty_mem ) {
4625 progress = this;
4626 // Cut inputs during Parse phase only.
4627 // During Optimize phase a dead MergeMem node will be subsumed by Top.
4628 if( !can_reshape ) {
4629 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4630 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
4631 }
4632 }
4633 }
4634
4635 if( !progress && base_memory()->is_Phi() && can_reshape ) {
4636 // Check if PhiNode::Ideal's "Split phis through memory merges"
4637 // transform should be attempted. Look for this->phi->this cycle.
4638 uint merge_width = req();
4639 if (merge_width > Compile::AliasIdxRaw) {
4640 PhiNode* phi = base_memory()->as_Phi();
4641 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
4642 if (phi->in(i) == this) {
4643 phase->is_IterGVN()->_worklist.push(phi);
4644 break;
4645 }
4646 }
4647 }
4648 }
4649
4650 assert(progress || verify_sparse(), "please, no dups of base");
4651 return progress;
4652 }
4653
4654 //-------------------------set_base_memory-------------------------------------
4655 void MergeMemNode::set_base_memory(Node *new_base) {
4656 Node* empty_mem = empty_memory();
4657 set_req(Compile::AliasIdxBot, new_base);
4658 assert(memory_at(req()) == new_base, "must set default memory");
4659 // Clear out other occurrences of new_base:
4660 if (new_base != empty_mem) {
4661 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4662 if (in(i) == new_base) set_req(i, empty_mem);
4663 }
4664 }
4665 }
4666
4667 //------------------------------out_RegMask------------------------------------
4668 const RegMask &MergeMemNode::out_RegMask() const {
4669 return RegMask::Empty;
4670 }
4671
4672 //------------------------------dump_spec--------------------------------------
4673 #ifndef PRODUCT
4674 void MergeMemNode::dump_spec(outputStream *st) const {
4675 st->print(" {");
4676 Node* base_mem = base_memory();
4677 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
4678 Node* mem = (in(i) != NULL) ? memory_at(i) : base_mem;
4679 if (mem == base_mem) { st->print(" -"); continue; }
4680 st->print( " N%d:", mem->_idx );
4681 Compile::current()->get_adr_type(i)->dump_on(st);
4682 }
4683 st->print(" }");
4684 }
4685 #endif // !PRODUCT
4686
4687
4688 #ifdef ASSERT
4689 static bool might_be_same(Node* a, Node* b) {
4690 if (a == b) return true;
4691 if (!(a->is_Phi() || b->is_Phi())) return false;
4692 // phis shift around during optimization
4693 return true; // pretty stupid...
4694 }
4695
4696 // verify a narrow slice (either incoming or outgoing)
4697 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
4698 if (!VerifyAliases) return; // don't bother to verify unless requested
4699 if (VMError::is_error_reported()) return; // muzzle asserts when debugging an error
4700 if (Node::in_dump()) return; // muzzle asserts when printing
4701 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
4702 assert(n != NULL, "");
4703 // Elide intervening MergeMem's
4704 while (n->is_MergeMem()) {
4705 n = n->as_MergeMem()->memory_at(alias_idx);
4706 }
4707 Compile* C = Compile::current();
4708 const TypePtr* n_adr_type = n->adr_type();
4709 if (n == m->empty_memory()) {
4710 // Implicit copy of base_memory()
4711 } else if (n_adr_type != TypePtr::BOTTOM) {
4712 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type");
4713 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
4714 } else {
4715 // A few places like make_runtime_call "know" that VM calls are narrow,
4716 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
4717 bool expected_wide_mem = false;
4718 if (n == m->base_memory()) {
4719 expected_wide_mem = true;
4720 } else if (alias_idx == Compile::AliasIdxRaw ||
4721 n == m->memory_at(Compile::AliasIdxRaw)) {
4722 expected_wide_mem = true;
4723 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
4724 // memory can "leak through" calls on channels that
4725 // are write-once. Allow this also.
4726 expected_wide_mem = true;
4727 }
4728 assert(expected_wide_mem, "expected narrow slice replacement");
4729 }
4730 }
4731 #else // !ASSERT
4732 #define verify_memory_slice(m,i,n) (void)(0) // PRODUCT version is no-op
4733 #endif
4734
4735
4736 //-----------------------------memory_at---------------------------------------
4737 Node* MergeMemNode::memory_at(uint alias_idx) const {
4738 assert(alias_idx >= Compile::AliasIdxRaw ||
4739 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0,
4740 "must avoid base_memory and AliasIdxTop");
4741
4742 // Otherwise, it is a narrow slice.
4743 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
4744 Compile *C = Compile::current();
4745 if (is_empty_memory(n)) {
4746 // the array is sparse; empty slots are the "top" node
4747 n = base_memory();
4748 assert(Node::in_dump()
4749 || n == NULL || n->bottom_type() == Type::TOP
4750 || n->adr_type() == NULL // address is TOP
4751 || n->adr_type() == TypePtr::BOTTOM
4752 || n->adr_type() == TypeRawPtr::BOTTOM
4753 || Compile::current()->AliasLevel() == 0,
4754 "must be a wide memory");
4755 // AliasLevel == 0 if we are organizing the memory states manually.
4756 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
4757 } else {
4758 // make sure the stored slice is sane
4759 #ifdef ASSERT
4760 if (VMError::is_error_reported() || Node::in_dump()) {
4761 } else if (might_be_same(n, base_memory())) {
4762 // Give it a pass: It is a mostly harmless repetition of the base.
4763 // This can arise normally from node subsumption during optimization.
4764 } else {
4765 verify_memory_slice(this, alias_idx, n);
4766 }
4767 #endif
4768 }
4769 return n;
4770 }
4771
4772 //---------------------------set_memory_at-------------------------------------
4773 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
4774 verify_memory_slice(this, alias_idx, n);
4775 Node* empty_mem = empty_memory();
4776 if (n == base_memory()) n = empty_mem; // collapse default
4777 uint need_req = alias_idx+1;
4778 if (req() < need_req) {
4779 if (n == empty_mem) return; // already the default, so do not grow me
4780 // grow the sparse array
4781 do {
4782 add_req(empty_mem);
4783 } while (req() < need_req);
4784 }
4785 set_req( alias_idx, n );
4786 }
4787
4788
4789
4790 //--------------------------iteration_setup------------------------------------
4791 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
4792 if (other != NULL) {
4793 grow_to_match(other);
4794 // invariant: the finite support of mm2 is within mm->req()
4795 #ifdef ASSERT
4796 for (uint i = req(); i < other->req(); i++) {
4797 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
4798 }
4799 #endif
4800 }
4801 // Replace spurious copies of base_memory by top.
4802 Node* base_mem = base_memory();
4803 if (base_mem != NULL && !base_mem->is_top()) {
4804 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
4805 if (in(i) == base_mem)
4806 set_req(i, empty_memory());
4807 }
4808 }
4809 }
4810
4811 //---------------------------grow_to_match-------------------------------------
4812 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
4813 Node* empty_mem = empty_memory();
4814 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
4815 // look for the finite support of the other memory
4816 for (uint i = other->req(); --i >= req(); ) {
4817 if (other->in(i) != empty_mem) {
4818 uint new_len = i+1;
4819 while (req() < new_len) add_req(empty_mem);
4820 break;
4821 }
4822 }
4823 }
4824
4825 //---------------------------verify_sparse-------------------------------------
4826 #ifndef PRODUCT
4827 bool MergeMemNode::verify_sparse() const {
4828 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
4829 Node* base_mem = base_memory();
4830 // The following can happen in degenerate cases, since empty==top.
4831 if (is_empty_memory(base_mem)) return true;
4832 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4833 assert(in(i) != NULL, "sane slice");
4834 if (in(i) == base_mem) return false; // should have been the sentinel value!
4835 }
4836 return true;
4837 }
4838
4839 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
4840 Node* n;
4841 n = mm->in(idx);
4842 if (mem == n) return true; // might be empty_memory()
4843 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
4844 if (mem == n) return true;
4845 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) {
4846 if (mem == n) return true;
4847 if (n == NULL) break;
4848 }
4849 return false;
4850 }
4851 #endif // !PRODUCT