1 /*
2 * Copyright (c) 1997, 2019, 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 #if INCLUDE_SHENANDOAHGC
56 #include "gc/shenandoah/c2/shenandoahBarrierSetC2.hpp"
57 #endif
58
59 // Portions of code courtesy of Clifford Click
60
61 // Optimization - Graph Style
62
63 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st);
64
65 //=============================================================================
66 uint MemNode::size_of() const { return sizeof(*this); }
67
68 const TypePtr *MemNode::adr_type() const {
69 Node* adr = in(Address);
70 if (adr == NULL) return NULL; // node is dead
71 const TypePtr* cross_check = NULL;
72 DEBUG_ONLY(cross_check = _adr_type);
73 return calculate_adr_type(adr->bottom_type(), cross_check);
74 }
75
76 bool MemNode::check_if_adr_maybe_raw(Node* adr) {
77 if (adr != NULL) {
78 if (adr->bottom_type()->base() == Type::RawPtr || adr->bottom_type()->base() == Type::AnyPtr) {
79 return true;
80 }
81 }
82 return false;
83 }
84
85 #ifndef PRODUCT
86 void MemNode::dump_spec(outputStream *st) const {
87 if (in(Address) == NULL) return; // node is dead
88 #ifndef ASSERT
89 // fake the missing field
90 const TypePtr* _adr_type = NULL;
91 if (in(Address) != NULL)
92 _adr_type = in(Address)->bottom_type()->isa_ptr();
93 #endif
94 dump_adr_type(this, _adr_type, st);
95
96 Compile* C = Compile::current();
97 if (C->alias_type(_adr_type)->is_volatile()) {
98 st->print(" Volatile!");
99 }
100 if (_unaligned_access) {
101 st->print(" unaligned");
102 }
103 if (_mismatched_access) {
104 st->print(" mismatched");
105 }
106 if (_unsafe_access) {
107 st->print(" unsafe");
108 }
109 }
110
111 void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) {
112 st->print(" @");
113 if (adr_type == NULL) {
114 st->print("NULL");
115 } else {
116 adr_type->dump_on(st);
117 Compile* C = Compile::current();
118 Compile::AliasType* atp = NULL;
119 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type);
120 if (atp == NULL)
121 st->print(", idx=?\?;");
122 else if (atp->index() == Compile::AliasIdxBot)
123 st->print(", idx=Bot;");
124 else if (atp->index() == Compile::AliasIdxTop)
125 st->print(", idx=Top;");
126 else if (atp->index() == Compile::AliasIdxRaw)
127 st->print(", idx=Raw;");
128 else {
129 ciField* field = atp->field();
130 if (field) {
131 st->print(", name=");
132 field->print_name_on(st);
133 }
134 st->print(", idx=%d;", atp->index());
135 }
136 }
137 }
138
139 extern void print_alias_types();
140
141 #endif
142
143 Node *MemNode::optimize_simple_memory_chain(Node *mchain, const TypeOopPtr *t_oop, Node *load, PhaseGVN *phase) {
144 assert((t_oop != NULL), "sanity");
145 bool is_instance = t_oop->is_known_instance_field();
146 bool is_boxed_value_load = t_oop->is_ptr_to_boxed_value() &&
147 (load != NULL) && load->is_Load() &&
148 (phase->is_IterGVN() != NULL);
149 if (!(is_instance || is_boxed_value_load))
150 return mchain; // don't try to optimize non-instance types
151 uint instance_id = t_oop->instance_id();
152 Node *start_mem = phase->C->start()->proj_out_or_null(TypeFunc::Memory);
153 Node *prev = NULL;
154 Node *result = mchain;
155 while (prev != result) {
156 prev = result;
157 if (result == start_mem)
158 break; // hit one of our sentinels
159 // skip over a call which does not affect this memory slice
160 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {
161 Node *proj_in = result->in(0);
162 if (proj_in->is_Allocate() && proj_in->_idx == instance_id) {
163 break; // hit one of our sentinels
164 } else if (proj_in->is_Call()) {
165 // ArrayCopyNodes processed here as well
166 CallNode *call = proj_in->as_Call();
167 if (!call->may_modify(t_oop, phase)) { // returns false for instances
168 result = call->in(TypeFunc::Memory);
169 }
170 } else if (proj_in->is_Initialize()) {
171 AllocateNode* alloc = proj_in->as_Initialize()->allocation();
172 // Stop if this is the initialization for the object instance which
173 // contains this memory slice, otherwise skip over it.
174 if ((alloc == NULL) || (alloc->_idx == instance_id)) {
175 break;
176 }
177 if (is_instance) {
178 result = proj_in->in(TypeFunc::Memory);
179 } else if (is_boxed_value_load) {
180 Node* klass = alloc->in(AllocateNode::KlassNode);
181 const TypeKlassPtr* tklass = phase->type(klass)->is_klassptr();
182 if (tklass->klass_is_exact() && !tklass->klass()->equals(t_oop->klass())) {
183 result = proj_in->in(TypeFunc::Memory); // not related allocation
184 }
185 }
186 } else if (proj_in->is_MemBar()) {
187 ArrayCopyNode* ac = NULL;
188 if (ArrayCopyNode::may_modify(t_oop, proj_in->as_MemBar(), phase, ac)) {
189 break;
190 }
191 result = proj_in->in(TypeFunc::Memory);
192 } else {
193 assert(false, "unexpected projection");
194 }
195 } else if (result->is_ClearArray()) {
196 if (!is_instance || !ClearArrayNode::step_through(&result, instance_id, phase)) {
197 // Can not bypass initialization of the instance
198 // we are looking for.
199 break;
200 }
201 // Otherwise skip it (the call updated 'result' value).
202 } else if (result->is_MergeMem()) {
203 result = step_through_mergemem(phase, result->as_MergeMem(), t_oop, NULL, tty);
204 }
205 }
206 return result;
207 }
208
209 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, Node *load, PhaseGVN *phase) {
210 const TypeOopPtr* t_oop = t_adr->isa_oopptr();
211 if (t_oop == NULL)
212 return mchain; // don't try to optimize non-oop types
213 Node* result = optimize_simple_memory_chain(mchain, t_oop, load, phase);
214 bool is_instance = t_oop->is_known_instance_field();
215 PhaseIterGVN *igvn = phase->is_IterGVN();
216 if (is_instance && igvn != NULL && result->is_Phi()) {
217 PhiNode *mphi = result->as_Phi();
218 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
219 const TypePtr *t = mphi->adr_type();
220 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
221 (t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
222 t->is_oopptr()->cast_to_exactness(true)
223 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
224 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop)) {
225 // clone the Phi with our address type
226 result = mphi->split_out_instance(t_adr, igvn);
227 } else {
228 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain");
229 }
230 }
231 return result;
232 }
233
234 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) {
235 uint alias_idx = phase->C->get_alias_index(tp);
236 Node *mem = mmem;
237 #ifdef ASSERT
238 {
239 // Check that current type is consistent with the alias index used during graph construction
240 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
241 bool consistent = adr_check == NULL || adr_check->empty() ||
242 phase->C->must_alias(adr_check, alias_idx );
243 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
244 if( !consistent && adr_check != NULL && !adr_check->empty() &&
245 tp->isa_aryptr() && tp->offset() == Type::OffsetBot &&
246 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot &&
247 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() ||
248 adr_check->offset() == oopDesc::klass_offset_in_bytes() ||
249 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) {
250 // don't assert if it is dead code.
251 consistent = true;
252 }
253 if( !consistent ) {
254 st->print("alias_idx==%d, adr_check==", alias_idx);
255 if( adr_check == NULL ) {
256 st->print("NULL");
257 } else {
258 adr_check->dump();
259 }
260 st->cr();
261 print_alias_types();
262 assert(consistent, "adr_check must match alias idx");
263 }
264 }
265 #endif
266 // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally
267 // means an array I have not precisely typed yet. Do not do any
268 // alias stuff with it any time soon.
269 const TypeOopPtr *toop = tp->isa_oopptr();
270 if( tp->base() != Type::AnyPtr &&
271 !(toop &&
272 toop->klass() != NULL &&
273 toop->klass()->is_java_lang_Object() &&
274 toop->offset() == Type::OffsetBot) ) {
275 // compress paths and change unreachable cycles to TOP
276 // If not, we can update the input infinitely along a MergeMem cycle
277 // Equivalent code in PhiNode::Ideal
278 Node* m = phase->transform(mmem);
279 // If transformed to a MergeMem, get the desired slice
280 // Otherwise the returned node represents memory for every slice
281 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
282 // Update input if it is progress over what we have now
283 }
284 return mem;
285 }
286
287 //--------------------------Ideal_common---------------------------------------
288 // Look for degenerate control and memory inputs. Bypass MergeMem inputs.
289 // Unhook non-raw memories from complete (macro-expanded) initializations.
290 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
291 // If our control input is a dead region, kill all below the region
292 Node *ctl = in(MemNode::Control);
293 if (ctl && remove_dead_region(phase, can_reshape))
294 return this;
295 ctl = in(MemNode::Control);
296 // Don't bother trying to transform a dead node
297 if (ctl && ctl->is_top()) return NodeSentinel;
298
299 PhaseIterGVN *igvn = phase->is_IterGVN();
300 // Wait if control on the worklist.
301 if (ctl && can_reshape && igvn != NULL) {
302 Node* bol = NULL;
303 Node* cmp = NULL;
304 if (ctl->in(0)->is_If()) {
305 assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity");
306 bol = ctl->in(0)->in(1);
307 if (bol->is_Bool())
308 cmp = ctl->in(0)->in(1)->in(1);
309 }
310 if (igvn->_worklist.member(ctl) ||
311 (bol != NULL && igvn->_worklist.member(bol)) ||
312 (cmp != NULL && igvn->_worklist.member(cmp)) ) {
313 // This control path may be dead.
314 // Delay this memory node transformation until the control is processed.
315 phase->is_IterGVN()->_worklist.push(this);
316 return NodeSentinel; // caller will return NULL
317 }
318 }
319 // Ignore if memory is dead, or self-loop
320 Node *mem = in(MemNode::Memory);
321 if (phase->type( mem ) == Type::TOP) return NodeSentinel; // caller will return NULL
322 assert(mem != this, "dead loop in MemNode::Ideal");
323
324 if (can_reshape && igvn != NULL && igvn->_worklist.member(mem)) {
325 // This memory slice may be dead.
326 // Delay this mem node transformation until the memory is processed.
327 phase->is_IterGVN()->_worklist.push(this);
328 return NodeSentinel; // caller will return NULL
329 }
330
331 Node *address = in(MemNode::Address);
332 const Type *t_adr = phase->type(address);
333 if (t_adr == Type::TOP) return NodeSentinel; // caller will return NULL
334
335 if (can_reshape && is_unsafe_access() && (t_adr == TypePtr::NULL_PTR)) {
336 // Unsafe off-heap access with zero address. Remove access and other control users
337 // to not confuse optimizations and add a HaltNode to fail if this is ever executed.
338 assert(ctl != NULL, "unsafe accesses should be control dependent");
339 for (DUIterator_Fast imax, i = ctl->fast_outs(imax); i < imax; i++) {
340 Node* u = ctl->fast_out(i);
341 if (u != ctl) {
342 igvn->rehash_node_delayed(u);
343 int nb = u->replace_edge(ctl, phase->C->top());
344 --i, imax -= nb;
345 }
346 }
347 Node* frame = igvn->transform(new ParmNode(phase->C->start(), TypeFunc::FramePtr));
348 Node* halt = igvn->transform(new HaltNode(ctl, frame, "unsafe off-heap access with zero address"));
349 phase->C->root()->add_req(halt);
350 return this;
351 }
352
353 if (can_reshape && igvn != NULL &&
354 (igvn->_worklist.member(address) ||
355 (igvn->_worklist.size() > 0 && t_adr != adr_type())) ) {
356 // The address's base and type may change when the address is processed.
357 // Delay this mem node transformation until the address is processed.
358 phase->is_IterGVN()->_worklist.push(this);
359 return NodeSentinel; // caller will return NULL
360 }
361
362 // Do NOT remove or optimize the next lines: ensure a new alias index
363 // is allocated for an oop pointer type before Escape Analysis.
364 // Note: C++ will not remove it since the call has side effect.
365 if (t_adr->isa_oopptr()) {
366 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr());
367 }
368
369 Node* base = NULL;
370 if (address->is_AddP()) {
371 base = address->in(AddPNode::Base);
372 }
373 if (base != NULL && phase->type(base)->higher_equal(TypePtr::NULL_PTR) &&
374 !t_adr->isa_rawptr()) {
375 // Note: raw address has TOP base and top->higher_equal(TypePtr::NULL_PTR) is true.
376 // Skip this node optimization if its address has TOP base.
377 return NodeSentinel; // caller will return NULL
378 }
379
380 // Avoid independent memory operations
381 Node* old_mem = mem;
382
383 // The code which unhooks non-raw memories from complete (macro-expanded)
384 // initializations was removed. After macro-expansion all stores catched
385 // by Initialize node became raw stores and there is no information
386 // which memory slices they modify. So it is unsafe to move any memory
387 // operation above these stores. Also in most cases hooked non-raw memories
388 // were already unhooked by using information from detect_ptr_independence()
389 // and find_previous_store().
390
391 if (mem->is_MergeMem()) {
392 MergeMemNode* mmem = mem->as_MergeMem();
393 const TypePtr *tp = t_adr->is_ptr();
394
395 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
396 }
397
398 if (mem != old_mem) {
399 set_req(MemNode::Memory, mem);
400 if (can_reshape && old_mem->outcnt() == 0 && igvn != NULL) {
401 igvn->_worklist.push(old_mem);
402 }
403 if (phase->type(mem) == Type::TOP) return NodeSentinel;
404 return this;
405 }
406
407 // let the subclass continue analyzing...
408 return NULL;
409 }
410
411 // Helper function for proving some simple control dominations.
412 // Attempt to prove that all control inputs of 'dom' dominate 'sub'.
413 // Already assumes that 'dom' is available at 'sub', and that 'sub'
414 // is not a constant (dominated by the method's StartNode).
415 // Used by MemNode::find_previous_store to prove that the
416 // control input of a memory operation predates (dominates)
417 // an allocation it wants to look past.
418 bool MemNode::all_controls_dominate(Node* dom, Node* sub) {
419 if (dom == NULL || dom->is_top() || sub == NULL || sub->is_top())
420 return false; // Conservative answer for dead code
421
422 // Check 'dom'. Skip Proj and CatchProj nodes.
423 dom = dom->find_exact_control(dom);
424 if (dom == NULL || dom->is_top())
425 return false; // Conservative answer for dead code
426
427 if (dom == sub) {
428 // For the case when, for example, 'sub' is Initialize and the original
429 // 'dom' is Proj node of the 'sub'.
430 return false;
431 }
432
433 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub)
434 return true;
435
436 // 'dom' dominates 'sub' if its control edge and control edges
437 // of all its inputs dominate or equal to sub's control edge.
438
439 // Currently 'sub' is either Allocate, Initialize or Start nodes.
440 // Or Region for the check in LoadNode::Ideal();
441 // 'sub' should have sub->in(0) != NULL.
442 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() ||
443 sub->is_Region() || sub->is_Call(), "expecting only these nodes");
444
445 // Get control edge of 'sub'.
446 Node* orig_sub = sub;
447 sub = sub->find_exact_control(sub->in(0));
448 if (sub == NULL || sub->is_top())
449 return false; // Conservative answer for dead code
450
451 assert(sub->is_CFG(), "expecting control");
452
453 if (sub == dom)
454 return true;
455
456 if (sub->is_Start() || sub->is_Root())
457 return false;
458
459 {
460 // Check all control edges of 'dom'.
461
462 ResourceMark rm;
463 Arena* arena = Thread::current()->resource_area();
464 Node_List nlist(arena);
465 Unique_Node_List dom_list(arena);
466
467 dom_list.push(dom);
468 bool only_dominating_controls = false;
469
470 for (uint next = 0; next < dom_list.size(); next++) {
471 Node* n = dom_list.at(next);
472 if (n == orig_sub)
473 return false; // One of dom's inputs dominated by sub.
474 if (!n->is_CFG() && n->pinned()) {
475 // Check only own control edge for pinned non-control nodes.
476 n = n->find_exact_control(n->in(0));
477 if (n == NULL || n->is_top())
478 return false; // Conservative answer for dead code
479 assert(n->is_CFG(), "expecting control");
480 dom_list.push(n);
481 } else if (n->is_Con() || n->is_Start() || n->is_Root()) {
482 only_dominating_controls = true;
483 } else if (n->is_CFG()) {
484 if (n->dominates(sub, nlist))
485 only_dominating_controls = true;
486 else
487 return false;
488 } else {
489 // First, own control edge.
490 Node* m = n->find_exact_control(n->in(0));
491 if (m != NULL) {
492 if (m->is_top())
493 return false; // Conservative answer for dead code
494 dom_list.push(m);
495 }
496 // Now, the rest of edges.
497 uint cnt = n->req();
498 for (uint i = 1; i < cnt; i++) {
499 m = n->find_exact_control(n->in(i));
500 if (m == NULL || m->is_top())
501 continue;
502 dom_list.push(m);
503 }
504 }
505 }
506 return only_dominating_controls;
507 }
508 }
509
510 //---------------------detect_ptr_independence---------------------------------
511 // Used by MemNode::find_previous_store to prove that two base
512 // pointers are never equal.
513 // The pointers are accompanied by their associated allocations,
514 // if any, which have been previously discovered by the caller.
515 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
516 Node* p2, AllocateNode* a2,
517 PhaseTransform* phase) {
518 // Attempt to prove that these two pointers cannot be aliased.
519 // They may both manifestly be allocations, and they should differ.
520 // Or, if they are not both allocations, they can be distinct constants.
521 // Otherwise, one is an allocation and the other a pre-existing value.
522 if (a1 == NULL && a2 == NULL) { // neither an allocation
523 return (p1 != p2) && p1->is_Con() && p2->is_Con();
524 } else if (a1 != NULL && a2 != NULL) { // both allocations
525 return (a1 != a2);
526 } else if (a1 != NULL) { // one allocation a1
527 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.)
528 return all_controls_dominate(p2, a1);
529 } else { //(a2 != NULL) // one allocation a2
530 return all_controls_dominate(p1, a2);
531 }
532 return false;
533 }
534
535
536 // Find an arraycopy that must have set (can_see_stored_value=true) or
537 // could have set (can_see_stored_value=false) the value for this load
538 Node* LoadNode::find_previous_arraycopy(PhaseTransform* phase, Node* ld_alloc, Node*& mem, bool can_see_stored_value) const {
539 if (mem->is_Proj() && mem->in(0) != NULL && (mem->in(0)->Opcode() == Op_MemBarStoreStore ||
540 mem->in(0)->Opcode() == Op_MemBarCPUOrder)) {
541 Node* mb = mem->in(0);
542 if (mb->in(0) != NULL && mb->in(0)->is_Proj() &&
543 mb->in(0)->in(0) != NULL && mb->in(0)->in(0)->is_ArrayCopy()) {
544 ArrayCopyNode* ac = mb->in(0)->in(0)->as_ArrayCopy();
545 if (ac->is_clonebasic()) {
546 intptr_t offset;
547 AllocateNode* alloc = AllocateNode::Ideal_allocation(ac->in(ArrayCopyNode::Dest), phase, offset);
548 if (alloc != NULL && alloc == ld_alloc) {
549 return ac;
550 }
551 }
552 }
553 } else if (mem->is_Proj() && mem->in(0) != NULL && mem->in(0)->is_ArrayCopy()) {
554 ArrayCopyNode* ac = mem->in(0)->as_ArrayCopy();
555
556 if (ac->is_arraycopy_validated() ||
557 ac->is_copyof_validated() ||
558 ac->is_copyofrange_validated()) {
559 Node* ld_addp = in(MemNode::Address);
560 if (ld_addp->is_AddP()) {
561 Node* ld_base = ld_addp->in(AddPNode::Address);
562 Node* ld_offs = ld_addp->in(AddPNode::Offset);
563
564 Node* dest = ac->in(ArrayCopyNode::Dest);
565
566 if (dest == ld_base) {
567 const TypeX *ld_offs_t = phase->type(ld_offs)->isa_intptr_t();
568 if (ac->modifies(ld_offs_t->_lo, ld_offs_t->_hi, phase, can_see_stored_value)) {
569 return ac;
570 }
571 if (!can_see_stored_value) {
572 mem = ac->in(TypeFunc::Memory);
573 }
574 }
575 }
576 }
577 }
578 return NULL;
579 }
580
581 // The logic for reordering loads and stores uses four steps:
582 // (a) Walk carefully past stores and initializations which we
583 // can prove are independent of this load.
584 // (b) Observe that the next memory state makes an exact match
585 // with self (load or store), and locate the relevant store.
586 // (c) Ensure that, if we were to wire self directly to the store,
587 // the optimizer would fold it up somehow.
588 // (d) Do the rewiring, and return, depending on some other part of
589 // the optimizer to fold up the load.
590 // This routine handles steps (a) and (b). Steps (c) and (d) are
591 // specific to loads and stores, so they are handled by the callers.
592 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.)
593 //
594 Node* MemNode::find_previous_store(PhaseTransform* phase) {
595 Node* ctrl = in(MemNode::Control);
596 Node* adr = in(MemNode::Address);
597 intptr_t offset = 0;
598 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
599 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase);
600
601 if (offset == Type::OffsetBot)
602 return NULL; // cannot unalias unless there are precise offsets
603
604 const bool adr_maybe_raw = check_if_adr_maybe_raw(adr);
605 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr();
606
607 intptr_t size_in_bytes = memory_size();
608
609 Node* mem = in(MemNode::Memory); // start searching here...
610
611 int cnt = 50; // Cycle limiter
612 for (;;) { // While we can dance past unrelated stores...
613 if (--cnt < 0) break; // Caught in cycle or a complicated dance?
614
615 Node* prev = mem;
616 if (mem->is_Store()) {
617 Node* st_adr = mem->in(MemNode::Address);
618 intptr_t st_offset = 0;
619 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
620 if (st_base == NULL)
621 break; // inscrutable pointer
622
623 // For raw accesses it's not enough to prove that constant offsets don't intersect.
624 // We need the bases to be the equal in order for the offset check to make sense.
625 if ((adr_maybe_raw || check_if_adr_maybe_raw(st_adr)) && st_base != base) {
626 break;
627 }
628
629 if (st_offset != offset && st_offset != Type::OffsetBot) {
630 const int MAX_STORE = BytesPerLong;
631 if (st_offset >= offset + size_in_bytes ||
632 st_offset <= offset - MAX_STORE ||
633 st_offset <= offset - mem->as_Store()->memory_size()) {
634 // Success: The offsets are provably independent.
635 // (You may ask, why not just test st_offset != offset and be done?
636 // The answer is that stores of different sizes can co-exist
637 // in the same sequence of RawMem effects. We sometimes initialize
638 // a whole 'tile' of array elements with a single jint or jlong.)
639 mem = mem->in(MemNode::Memory);
640 continue; // (a) advance through independent store memory
641 }
642 }
643 if (st_base != base &&
644 detect_ptr_independence(base, alloc,
645 st_base,
646 AllocateNode::Ideal_allocation(st_base, phase),
647 phase)) {
648 // Success: The bases are provably independent.
649 mem = mem->in(MemNode::Memory);
650 continue; // (a) advance through independent store memory
651 }
652
653 // (b) At this point, if the bases or offsets do not agree, we lose,
654 // since we have not managed to prove 'this' and 'mem' independent.
655 if (st_base == base && st_offset == offset) {
656 return mem; // let caller handle steps (c), (d)
657 }
658
659 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
660 InitializeNode* st_init = mem->in(0)->as_Initialize();
661 AllocateNode* st_alloc = st_init->allocation();
662 if (st_alloc == NULL)
663 break; // something degenerated
664 bool known_identical = false;
665 bool known_independent = false;
666 if (alloc == st_alloc)
667 known_identical = true;
668 else if (alloc != NULL)
669 known_independent = true;
670 else if (all_controls_dominate(this, st_alloc))
671 known_independent = true;
672
673 if (known_independent) {
674 // The bases are provably independent: Either they are
675 // manifestly distinct allocations, or else the control
676 // of this load dominates the store's allocation.
677 int alias_idx = phase->C->get_alias_index(adr_type());
678 if (alias_idx == Compile::AliasIdxRaw) {
679 mem = st_alloc->in(TypeFunc::Memory);
680 } else {
681 mem = st_init->memory(alias_idx);
682 }
683 continue; // (a) advance through independent store memory
684 }
685
686 // (b) at this point, if we are not looking at a store initializing
687 // the same allocation we are loading from, we lose.
688 if (known_identical) {
689 // From caller, can_see_stored_value will consult find_captured_store.
690 return mem; // let caller handle steps (c), (d)
691 }
692
693 } else if (find_previous_arraycopy(phase, alloc, mem, false) != NULL) {
694 if (prev != mem) {
695 // Found an arraycopy but it doesn't affect that load
696 continue;
697 }
698 // Found an arraycopy that may affect that load
699 return mem;
700 } else if (addr_t != NULL && addr_t->is_known_instance_field()) {
701 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
702 if (mem->is_Proj() && mem->in(0)->is_Call()) {
703 // ArrayCopyNodes processed here as well.
704 CallNode *call = mem->in(0)->as_Call();
705 if (!call->may_modify(addr_t, phase)) {
706 mem = call->in(TypeFunc::Memory);
707 continue; // (a) advance through independent call memory
708 }
709 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) {
710 ArrayCopyNode* ac = NULL;
711 if (ArrayCopyNode::may_modify(addr_t, mem->in(0)->as_MemBar(), phase, ac)) {
712 break;
713 }
714 mem = mem->in(0)->in(TypeFunc::Memory);
715 continue; // (a) advance through independent MemBar memory
716 } else if (mem->is_ClearArray()) {
717 if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) {
718 // (the call updated 'mem' value)
719 continue; // (a) advance through independent allocation memory
720 } else {
721 // Can not bypass initialization of the instance
722 // we are looking for.
723 return mem;
724 }
725 } else if (mem->is_MergeMem()) {
726 int alias_idx = phase->C->get_alias_index(adr_type());
727 mem = mem->as_MergeMem()->memory_at(alias_idx);
728 continue; // (a) advance through independent MergeMem memory
729 }
730 }
731
732 // Unless there is an explicit 'continue', we must bail out here,
733 // because 'mem' is an inscrutable memory state (e.g., a call).
734 break;
735 }
736
737 return NULL; // bail out
738 }
739
740 //----------------------calculate_adr_type-------------------------------------
741 // Helper function. Notices when the given type of address hits top or bottom.
742 // Also, asserts a cross-check of the type against the expected address type.
743 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
744 if (t == Type::TOP) return NULL; // does not touch memory any more?
745 #ifdef PRODUCT
746 cross_check = NULL;
747 #else
748 if (!VerifyAliases || VMError::is_error_reported() || Node::in_dump()) cross_check = NULL;
749 #endif
750 const TypePtr* tp = t->isa_ptr();
751 if (tp == NULL) {
752 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
753 return TypePtr::BOTTOM; // touches lots of memory
754 } else {
755 #ifdef ASSERT
756 // %%%% [phh] We don't check the alias index if cross_check is
757 // TypeRawPtr::BOTTOM. Needs to be investigated.
758 if (cross_check != NULL &&
759 cross_check != TypePtr::BOTTOM &&
760 cross_check != TypeRawPtr::BOTTOM) {
761 // Recheck the alias index, to see if it has changed (due to a bug).
762 Compile* C = Compile::current();
763 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
764 "must stay in the original alias category");
765 // The type of the address must be contained in the adr_type,
766 // disregarding "null"-ness.
767 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
768 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
769 assert(cross_check->meet(tp_notnull) == cross_check->remove_speculative(),
770 "real address must not escape from expected memory type");
771 }
772 #endif
773 return tp;
774 }
775 }
776
777 //=============================================================================
778 // Should LoadNode::Ideal() attempt to remove control edges?
779 bool LoadNode::can_remove_control() const {
780 return true;
781 }
782 uint LoadNode::size_of() const { return sizeof(*this); }
783 uint LoadNode::cmp( const Node &n ) const
784 { return !Type::cmp( _type, ((LoadNode&)n)._type ); }
785 const Type *LoadNode::bottom_type() const { return _type; }
786 uint LoadNode::ideal_reg() const {
787 return _type->ideal_reg();
788 }
789
790 #ifndef PRODUCT
791 void LoadNode::dump_spec(outputStream *st) const {
792 MemNode::dump_spec(st);
793 if( !Verbose && !WizardMode ) {
794 // standard dump does this in Verbose and WizardMode
795 st->print(" #"); _type->dump_on(st);
796 }
797 if (!depends_only_on_test()) {
798 st->print(" (does not depend only on test)");
799 }
800 }
801 #endif
802
803 #ifdef ASSERT
804 //----------------------------is_immutable_value-------------------------------
805 // Helper function to allow a raw load without control edge for some cases
806 bool LoadNode::is_immutable_value(Node* adr) {
807 return (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() &&
808 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal &&
809 (adr->in(AddPNode::Offset)->find_intptr_t_con(-1) ==
810 in_bytes(JavaThread::osthread_offset())));
811 }
812 #endif
813
814 //----------------------------LoadNode::make-----------------------------------
815 // Polymorphic factory method:
816 Node *LoadNode::make(PhaseGVN& gvn, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt, MemOrd mo,
817 ControlDependency control_dependency, bool unaligned, bool mismatched, bool unsafe) {
818 Compile* C = gvn.C;
819
820 // sanity check the alias category against the created node type
821 assert(!(adr_type->isa_oopptr() &&
822 adr_type->offset() == oopDesc::klass_offset_in_bytes()),
823 "use LoadKlassNode instead");
824 assert(!(adr_type->isa_aryptr() &&
825 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
826 "use LoadRangeNode instead");
827 // Check control edge of raw loads
828 assert( ctl != NULL || C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
829 // oop will be recorded in oop map if load crosses safepoint
830 rt->isa_oopptr() || is_immutable_value(adr),
831 "raw memory operations should have control edge");
832 LoadNode* load = NULL;
833 switch (bt) {
834 case T_BOOLEAN: load = new LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
835 case T_BYTE: load = new LoadBNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
836 case T_INT: load = new LoadINode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
837 case T_CHAR: load = new LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
838 case T_SHORT: load = new LoadSNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
839 case T_LONG: load = new LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency); break;
840 case T_FLOAT: load = new LoadFNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); break;
841 case T_DOUBLE: load = new LoadDNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); break;
842 case T_ADDRESS: load = new LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency); break;
843 case T_OBJECT:
844 #ifdef _LP64
845 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
846 load = new LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo, control_dependency);
847 } else
848 #endif
849 {
850 assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop");
851 load = new LoadPNode(ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency);
852 }
853 break;
854 default:
855 ShouldNotReachHere();
856 break;
857 }
858 assert(load != NULL, "LoadNode should have been created");
859 if (unaligned) {
860 load->set_unaligned_access();
861 }
862 if (mismatched) {
863 load->set_mismatched_access();
864 }
865 if (unsafe) {
866 load->set_unsafe_access();
867 }
868 if (load->Opcode() == Op_LoadN) {
869 Node* ld = gvn.transform(load);
870 return new DecodeNNode(ld, ld->bottom_type()->make_ptr());
871 }
872
873 return load;
874 }
875
876 LoadLNode* LoadLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo,
877 ControlDependency control_dependency, bool unaligned, bool mismatched, bool unsafe) {
878 bool require_atomic = true;
879 LoadLNode* load = new LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency, require_atomic);
880 if (unaligned) {
881 load->set_unaligned_access();
882 }
883 if (mismatched) {
884 load->set_mismatched_access();
885 }
886 if (unsafe) {
887 load->set_unsafe_access();
888 }
889 return load;
890 }
891
892 LoadDNode* LoadDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo,
893 ControlDependency control_dependency, bool unaligned, bool mismatched, bool unsafe) {
894 bool require_atomic = true;
895 LoadDNode* load = new LoadDNode(ctl, mem, adr, adr_type, rt, mo, control_dependency, require_atomic);
896 if (unaligned) {
897 load->set_unaligned_access();
898 }
899 if (mismatched) {
900 load->set_mismatched_access();
901 }
902 if (unsafe) {
903 load->set_unsafe_access();
904 }
905 return load;
906 }
907
908
909
910 //------------------------------hash-------------------------------------------
911 uint LoadNode::hash() const {
912 // unroll addition of interesting fields
913 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
914 }
915
916 static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) {
917 if ((atp != NULL) && (atp->index() >= Compile::AliasIdxRaw)) {
918 bool non_volatile = (atp->field() != NULL) && !atp->field()->is_volatile();
919 bool is_stable_ary = FoldStableValues &&
920 (tp != NULL) && (tp->isa_aryptr() != NULL) &&
921 tp->isa_aryptr()->is_stable();
922
923 return (eliminate_boxing && non_volatile) || is_stable_ary;
924 }
925
926 return false;
927 }
928
929 // Is the value loaded previously stored by an arraycopy? If so return
930 // a load node that reads from the source array so we may be able to
931 // optimize out the ArrayCopy node later.
932 Node* LoadNode::can_see_arraycopy_value(Node* st, PhaseGVN* phase) const {
933 #if INCLUDE_ZGC
934 if (UseZGC) {
935 if (bottom_type()->make_oopptr() != NULL) {
936 return NULL;
937 }
938 }
939 #endif
940
941 Node* ld_adr = in(MemNode::Address);
942 intptr_t ld_off = 0;
943 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
944 Node* ac = find_previous_arraycopy(phase, ld_alloc, st, true);
945 if (ac != NULL) {
946 assert(ac->is_ArrayCopy(), "what kind of node can this be?");
947
948 Node* mem = ac->in(TypeFunc::Memory);
949 Node* ctl = ac->in(0);
950 Node* src = ac->in(ArrayCopyNode::Src);
951
952 if (!ac->as_ArrayCopy()->is_clonebasic() && !phase->type(src)->isa_aryptr()) {
953 return NULL;
954 }
955
956 LoadNode* ld = clone()->as_Load();
957 Node* addp = in(MemNode::Address)->clone();
958 if (ac->as_ArrayCopy()->is_clonebasic()) {
959 assert(ld_alloc != NULL, "need an alloc");
960 assert(addp->is_AddP(), "address must be addp");
961 assert(addp->in(AddPNode::Base) == ac->in(ArrayCopyNode::Dest)->in(AddPNode::Base), "strange pattern");
962 assert(addp->in(AddPNode::Address) == ac->in(ArrayCopyNode::Dest)->in(AddPNode::Address), "strange pattern");
963 addp->set_req(AddPNode::Base, src->in(AddPNode::Base));
964 addp->set_req(AddPNode::Address, src->in(AddPNode::Address));
965 } else {
966 assert(ac->as_ArrayCopy()->is_arraycopy_validated() ||
967 ac->as_ArrayCopy()->is_copyof_validated() ||
968 ac->as_ArrayCopy()->is_copyofrange_validated(), "only supported cases");
969 assert(addp->in(AddPNode::Base) == addp->in(AddPNode::Address), "should be");
970 addp->set_req(AddPNode::Base, src);
971 addp->set_req(AddPNode::Address, src);
972
973 const TypeAryPtr* ary_t = phase->type(in(MemNode::Address))->isa_aryptr();
974 BasicType ary_elem = ary_t->klass()->as_array_klass()->element_type()->basic_type();
975 uint header = arrayOopDesc::base_offset_in_bytes(ary_elem);
976 uint shift = exact_log2(type2aelembytes(ary_elem));
977
978 Node* diff = phase->transform(new SubINode(ac->in(ArrayCopyNode::SrcPos), ac->in(ArrayCopyNode::DestPos)));
979 #ifdef _LP64
980 diff = phase->transform(new ConvI2LNode(diff));
981 #endif
982 diff = phase->transform(new LShiftXNode(diff, phase->intcon(shift)));
983
984 Node* offset = phase->transform(new AddXNode(addp->in(AddPNode::Offset), diff));
985 addp->set_req(AddPNode::Offset, offset);
986 }
987 addp = phase->transform(addp);
988 #ifdef ASSERT
989 const TypePtr* adr_type = phase->type(addp)->is_ptr();
990 ld->_adr_type = adr_type;
991 #endif
992 ld->set_req(MemNode::Address, addp);
993 ld->set_req(0, ctl);
994 ld->set_req(MemNode::Memory, mem);
995 // load depends on the tests that validate the arraycopy
996 ld->_control_dependency = Pinned;
997 return ld;
998 }
999 return NULL;
1000 }
1001
1002
1003 //---------------------------can_see_stored_value------------------------------
1004 // This routine exists to make sure this set of tests is done the same
1005 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
1006 // will change the graph shape in a way which makes memory alive twice at the
1007 // same time (uses the Oracle model of aliasing), then some
1008 // LoadXNode::Identity will fold things back to the equivalence-class model
1009 // of aliasing.
1010 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const {
1011 Node* ld_adr = in(MemNode::Address);
1012 intptr_t ld_off = 0;
1013 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
1014 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
1015 Compile::AliasType* atp = (tp != NULL) ? phase->C->alias_type(tp) : NULL;
1016 // This is more general than load from boxing objects.
1017 if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) {
1018 uint alias_idx = atp->index();
1019 bool final = !atp->is_rewritable();
1020 Node* result = NULL;
1021 Node* current = st;
1022 // Skip through chains of MemBarNodes checking the MergeMems for
1023 // new states for the slice of this load. Stop once any other
1024 // kind of node is encountered. Loads from final memory can skip
1025 // through any kind of MemBar but normal loads shouldn't skip
1026 // through MemBarAcquire since the could allow them to move out of
1027 // a synchronized region.
1028 while (current->is_Proj()) {
1029 int opc = current->in(0)->Opcode();
1030 if ((final && (opc == Op_MemBarAcquire ||
1031 opc == Op_MemBarAcquireLock ||
1032 opc == Op_LoadFence)) ||
1033 opc == Op_MemBarRelease ||
1034 opc == Op_StoreFence ||
1035 opc == Op_MemBarReleaseLock ||
1036 opc == Op_MemBarStoreStore ||
1037 opc == Op_MemBarCPUOrder) {
1038 Node* mem = current->in(0)->in(TypeFunc::Memory);
1039 if (mem->is_MergeMem()) {
1040 MergeMemNode* merge = mem->as_MergeMem();
1041 Node* new_st = merge->memory_at(alias_idx);
1042 if (new_st == merge->base_memory()) {
1043 // Keep searching
1044 current = new_st;
1045 continue;
1046 }
1047 // Save the new memory state for the slice and fall through
1048 // to exit.
1049 result = new_st;
1050 }
1051 }
1052 break;
1053 }
1054 if (result != NULL) {
1055 st = result;
1056 }
1057 }
1058
1059 // Loop around twice in the case Load -> Initialize -> Store.
1060 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
1061 for (int trip = 0; trip <= 1; trip++) {
1062
1063 if (st->is_Store()) {
1064 Node* st_adr = st->in(MemNode::Address);
1065 if (!phase->eqv(st_adr, ld_adr)) {
1066 // Try harder before giving up... Match raw and non-raw pointers.
1067 intptr_t st_off = 0;
1068 AllocateNode* alloc = AllocateNode::Ideal_allocation(st_adr, phase, st_off);
1069 if (alloc == NULL) return NULL;
1070 if (alloc != ld_alloc) return NULL;
1071 if (ld_off != st_off) return NULL;
1072 // At this point we have proven something like this setup:
1073 // A = Allocate(...)
1074 // L = LoadQ(, AddP(CastPP(, A.Parm),, #Off))
1075 // S = StoreQ(, AddP(, A.Parm , #Off), V)
1076 // (Actually, we haven't yet proven the Q's are the same.)
1077 // In other words, we are loading from a casted version of
1078 // the same pointer-and-offset that we stored to.
1079 // Thus, we are able to replace L by V.
1080 }
1081 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
1082 if (store_Opcode() != st->Opcode())
1083 return NULL;
1084 return st->in(MemNode::ValueIn);
1085 }
1086
1087 // A load from a freshly-created object always returns zero.
1088 // (This can happen after LoadNode::Ideal resets the load's memory input
1089 // to find_captured_store, which returned InitializeNode::zero_memory.)
1090 if (st->is_Proj() && st->in(0)->is_Allocate() &&
1091 (st->in(0) == ld_alloc) &&
1092 (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) {
1093 // return a zero value for the load's basic type
1094 // (This is one of the few places where a generic PhaseTransform
1095 // can create new nodes. Think of it as lazily manifesting
1096 // virtually pre-existing constants.)
1097 return phase->zerocon(memory_type());
1098 }
1099
1100 // A load from an initialization barrier can match a captured store.
1101 if (st->is_Proj() && st->in(0)->is_Initialize()) {
1102 InitializeNode* init = st->in(0)->as_Initialize();
1103 AllocateNode* alloc = init->allocation();
1104 if ((alloc != NULL) && (alloc == ld_alloc)) {
1105 // examine a captured store value
1106 st = init->find_captured_store(ld_off, memory_size(), phase);
1107 if (st != NULL) {
1108 continue; // take one more trip around
1109 }
1110 }
1111 }
1112
1113 // Load boxed value from result of valueOf() call is input parameter.
1114 if (this->is_Load() && ld_adr->is_AddP() &&
1115 (tp != NULL) && tp->is_ptr_to_boxed_value()) {
1116 intptr_t ignore = 0;
1117 Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore);
1118 #if INCLUDE_SHENANDOAHGC
1119 if (UseShenandoahGC) {
1120 base = ((ShenandoahBarrierSetC2*) BarrierSet::barrier_set()->barrier_set_c2())->step_over_gc_barrier(base);
1121 }
1122 #endif
1123 if (base != NULL && base->is_Proj() &&
1124 base->as_Proj()->_con == TypeFunc::Parms &&
1125 base->in(0)->is_CallStaticJava() &&
1126 base->in(0)->as_CallStaticJava()->is_boxing_method()) {
1127 return base->in(0)->in(TypeFunc::Parms);
1128 }
1129 }
1130
1131 break;
1132 }
1133
1134 return NULL;
1135 }
1136
1137 //----------------------is_instance_field_load_with_local_phi------------------
1138 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
1139 if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl &&
1140 in(Address)->is_AddP() ) {
1141 const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr();
1142 // Only instances and boxed values.
1143 if( t_oop != NULL &&
1144 (t_oop->is_ptr_to_boxed_value() ||
1145 t_oop->is_known_instance_field()) &&
1146 t_oop->offset() != Type::OffsetBot &&
1147 t_oop->offset() != Type::OffsetTop) {
1148 return true;
1149 }
1150 }
1151 return false;
1152 }
1153
1154 //------------------------------Identity---------------------------------------
1155 // Loads are identity if previous store is to same address
1156 Node* LoadNode::Identity(PhaseGVN* phase) {
1157 // If the previous store-maker is the right kind of Store, and the store is
1158 // to the same address, then we are equal to the value stored.
1159 Node* mem = in(Memory);
1160 Node* value = can_see_stored_value(mem, phase);
1161 if( value ) {
1162 // byte, short & char stores truncate naturally.
1163 // A load has to load the truncated value which requires
1164 // some sort of masking operation and that requires an
1165 // Ideal call instead of an Identity call.
1166 if (memory_size() < BytesPerInt) {
1167 // If the input to the store does not fit with the load's result type,
1168 // it must be truncated via an Ideal call.
1169 if (!phase->type(value)->higher_equal(phase->type(this)))
1170 return this;
1171 }
1172 // (This works even when value is a Con, but LoadNode::Value
1173 // usually runs first, producing the singleton type of the Con.)
1174 return value;
1175 }
1176
1177 // Search for an existing data phi which was generated before for the same
1178 // instance's field to avoid infinite generation of phis in a loop.
1179 Node *region = mem->in(0);
1180 if (is_instance_field_load_with_local_phi(region)) {
1181 const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr();
1182 int this_index = phase->C->get_alias_index(addr_t);
1183 int this_offset = addr_t->offset();
1184 int this_iid = addr_t->instance_id();
1185 if (!addr_t->is_known_instance() &&
1186 addr_t->is_ptr_to_boxed_value()) {
1187 // Use _idx of address base (could be Phi node) for boxed values.
1188 intptr_t ignore = 0;
1189 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1190 if (base == NULL) {
1191 return this;
1192 }
1193 this_iid = base->_idx;
1194 }
1195 const Type* this_type = bottom_type();
1196 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1197 Node* phi = region->fast_out(i);
1198 if (phi->is_Phi() && phi != mem &&
1199 phi->as_Phi()->is_same_inst_field(this_type, (int)mem->_idx, this_iid, this_index, this_offset)) {
1200 return phi;
1201 }
1202 }
1203 }
1204
1205 return this;
1206 }
1207
1208 // Construct an equivalent unsigned load.
1209 Node* LoadNode::convert_to_unsigned_load(PhaseGVN& gvn) {
1210 BasicType bt = T_ILLEGAL;
1211 const Type* rt = NULL;
1212 switch (Opcode()) {
1213 case Op_LoadUB: return this;
1214 case Op_LoadUS: return this;
1215 case Op_LoadB: bt = T_BOOLEAN; rt = TypeInt::UBYTE; break;
1216 case Op_LoadS: bt = T_CHAR; rt = TypeInt::CHAR; break;
1217 default:
1218 assert(false, "no unsigned variant: %s", Name());
1219 return NULL;
1220 }
1221 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1222 raw_adr_type(), rt, bt, _mo, _control_dependency,
1223 is_unaligned_access(), is_mismatched_access());
1224 }
1225
1226 // Construct an equivalent signed load.
1227 Node* LoadNode::convert_to_signed_load(PhaseGVN& gvn) {
1228 BasicType bt = T_ILLEGAL;
1229 const Type* rt = NULL;
1230 switch (Opcode()) {
1231 case Op_LoadUB: bt = T_BYTE; rt = TypeInt::BYTE; break;
1232 case Op_LoadUS: bt = T_SHORT; rt = TypeInt::SHORT; break;
1233 case Op_LoadB: // fall through
1234 case Op_LoadS: // fall through
1235 case Op_LoadI: // fall through
1236 case Op_LoadL: return this;
1237 default:
1238 assert(false, "no signed variant: %s", Name());
1239 return NULL;
1240 }
1241 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1242 raw_adr_type(), rt, bt, _mo, _control_dependency,
1243 is_unaligned_access(), is_mismatched_access());
1244 }
1245
1246 // We're loading from an object which has autobox behaviour.
1247 // If this object is result of a valueOf call we'll have a phi
1248 // merging a newly allocated object and a load from the cache.
1249 // We want to replace this load with the original incoming
1250 // argument to the valueOf call.
1251 Node* LoadNode::eliminate_autobox(PhaseGVN* phase) {
1252 assert(phase->C->eliminate_boxing(), "sanity");
1253 intptr_t ignore = 0;
1254 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1255 if ((base == NULL) || base->is_Phi()) {
1256 // Push the loads from the phi that comes from valueOf up
1257 // through it to allow elimination of the loads and the recovery
1258 // of the original value. It is done in split_through_phi().
1259 return NULL;
1260 } else if (base->is_Load() ||
1261 (base->is_DecodeN() && base->in(1)->is_Load())) {
1262 // Eliminate the load of boxed value for integer types from the cache
1263 // array by deriving the value from the index into the array.
1264 // Capture the offset of the load and then reverse the computation.
1265
1266 // Get LoadN node which loads a boxing object from 'cache' array.
1267 if (base->is_DecodeN()) {
1268 base = base->in(1);
1269 }
1270 if (!base->in(Address)->is_AddP()) {
1271 return NULL; // Complex address
1272 }
1273 AddPNode* address = base->in(Address)->as_AddP();
1274 Node* cache_base = address->in(AddPNode::Base);
1275 if ((cache_base != NULL) && cache_base->is_DecodeN()) {
1276 // Get ConP node which is static 'cache' field.
1277 cache_base = cache_base->in(1);
1278 }
1279 if ((cache_base != NULL) && cache_base->is_Con()) {
1280 const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr();
1281 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1282 Node* elements[4];
1283 int shift = exact_log2(type2aelembytes(T_OBJECT));
1284 int count = address->unpack_offsets(elements, ARRAY_SIZE(elements));
1285 if (count > 0 && elements[0]->is_Con() &&
1286 (count == 1 ||
1287 (count == 2 && elements[1]->Opcode() == Op_LShiftX &&
1288 elements[1]->in(2) == phase->intcon(shift)))) {
1289 ciObjArray* array = base_type->const_oop()->as_obj_array();
1290 // Fetch the box object cache[0] at the base of the array and get its value
1291 ciInstance* box = array->obj_at(0)->as_instance();
1292 ciInstanceKlass* ik = box->klass()->as_instance_klass();
1293 assert(ik->is_box_klass(), "sanity");
1294 assert(ik->nof_nonstatic_fields() == 1, "change following code");
1295 if (ik->nof_nonstatic_fields() == 1) {
1296 // This should be true nonstatic_field_at requires calling
1297 // nof_nonstatic_fields so check it anyway
1298 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1299 BasicType bt = c.basic_type();
1300 // Only integer types have boxing cache.
1301 assert(bt == T_BOOLEAN || bt == T_CHAR ||
1302 bt == T_BYTE || bt == T_SHORT ||
1303 bt == T_INT || bt == T_LONG, "wrong type = %s", type2name(bt));
1304 jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int();
1305 if (cache_low != (int)cache_low) {
1306 return NULL; // should not happen since cache is array indexed by value
1307 }
1308 jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift);
1309 if (offset != (int)offset) {
1310 return NULL; // should not happen since cache is array indexed by value
1311 }
1312 // Add up all the offsets making of the address of the load
1313 Node* result = elements[0];
1314 for (int i = 1; i < count; i++) {
1315 result = phase->transform(new AddXNode(result, elements[i]));
1316 }
1317 // Remove the constant offset from the address and then
1318 result = phase->transform(new AddXNode(result, phase->MakeConX(-(int)offset)));
1319 // remove the scaling of the offset to recover the original index.
1320 if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) {
1321 // Peel the shift off directly but wrap it in a dummy node
1322 // since Ideal can't return existing nodes
1323 result = new RShiftXNode(result->in(1), phase->intcon(0));
1324 } else if (result->is_Add() && result->in(2)->is_Con() &&
1325 result->in(1)->Opcode() == Op_LShiftX &&
1326 result->in(1)->in(2) == phase->intcon(shift)) {
1327 // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z)
1328 // but for boxing cache access we know that X<<Z will not overflow
1329 // (there is range check) so we do this optimizatrion by hand here.
1330 Node* add_con = new RShiftXNode(result->in(2), phase->intcon(shift));
1331 result = new AddXNode(result->in(1)->in(1), phase->transform(add_con));
1332 } else {
1333 result = new RShiftXNode(result, phase->intcon(shift));
1334 }
1335 #ifdef _LP64
1336 if (bt != T_LONG) {
1337 result = new ConvL2INode(phase->transform(result));
1338 }
1339 #else
1340 if (bt == T_LONG) {
1341 result = new ConvI2LNode(phase->transform(result));
1342 }
1343 #endif
1344 // Boxing/unboxing can be done from signed & unsigned loads (e.g. LoadUB -> ... -> LoadB pair).
1345 // Need to preserve unboxing load type if it is unsigned.
1346 switch(this->Opcode()) {
1347 case Op_LoadUB:
1348 result = new AndINode(phase->transform(result), phase->intcon(0xFF));
1349 break;
1350 case Op_LoadUS:
1351 result = new AndINode(phase->transform(result), phase->intcon(0xFFFF));
1352 break;
1353 }
1354 return result;
1355 }
1356 }
1357 }
1358 }
1359 }
1360 return NULL;
1361 }
1362
1363 static bool stable_phi(PhiNode* phi, PhaseGVN *phase) {
1364 Node* region = phi->in(0);
1365 if (region == NULL) {
1366 return false; // Wait stable graph
1367 }
1368 uint cnt = phi->req();
1369 for (uint i = 1; i < cnt; i++) {
1370 Node* rc = region->in(i);
1371 if (rc == NULL || phase->type(rc) == Type::TOP)
1372 return false; // Wait stable graph
1373 Node* in = phi->in(i);
1374 if (in == NULL || phase->type(in) == Type::TOP)
1375 return false; // Wait stable graph
1376 }
1377 return true;
1378 }
1379 //------------------------------split_through_phi------------------------------
1380 // Split instance or boxed field load through Phi.
1381 Node *LoadNode::split_through_phi(PhaseGVN *phase) {
1382 Node* mem = in(Memory);
1383 Node* address = in(Address);
1384 const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr();
1385
1386 assert((t_oop != NULL) &&
1387 (t_oop->is_known_instance_field() ||
1388 t_oop->is_ptr_to_boxed_value()), "invalide conditions");
1389
1390 Compile* C = phase->C;
1391 intptr_t ignore = 0;
1392 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1393 bool base_is_phi = (base != NULL) && base->is_Phi();
1394 bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() &&
1395 (base != NULL) && (base == address->in(AddPNode::Base)) &&
1396 phase->type(base)->higher_equal(TypePtr::NOTNULL);
1397
1398 if (!((mem->is_Phi() || base_is_phi) &&
1399 (load_boxed_values || t_oop->is_known_instance_field()))) {
1400 return NULL; // memory is not Phi
1401 }
1402
1403 if (mem->is_Phi()) {
1404 if (!stable_phi(mem->as_Phi(), phase)) {
1405 return NULL; // Wait stable graph
1406 }
1407 uint cnt = mem->req();
1408 // Check for loop invariant memory.
1409 if (cnt == 3) {
1410 for (uint i = 1; i < cnt; i++) {
1411 Node* in = mem->in(i);
1412 Node* m = optimize_memory_chain(in, t_oop, this, phase);
1413 if (m == mem) {
1414 if (i == 1) {
1415 // if the first edge was a loop, check second edge too.
1416 // If both are replaceable - we are in an infinite loop
1417 Node *n = optimize_memory_chain(mem->in(2), t_oop, this, phase);
1418 if (n == mem) {
1419 break;
1420 }
1421 }
1422 set_req(Memory, mem->in(cnt - i));
1423 return this; // made change
1424 }
1425 }
1426 }
1427 }
1428 if (base_is_phi) {
1429 if (!stable_phi(base->as_Phi(), phase)) {
1430 return NULL; // Wait stable graph
1431 }
1432 uint cnt = base->req();
1433 // Check for loop invariant memory.
1434 if (cnt == 3) {
1435 for (uint i = 1; i < cnt; i++) {
1436 if (base->in(i) == base) {
1437 return NULL; // Wait stable graph
1438 }
1439 }
1440 }
1441 }
1442
1443 bool load_boxed_phi = load_boxed_values && base_is_phi && (base->in(0) == mem->in(0));
1444
1445 // Split through Phi (see original code in loopopts.cpp).
1446 assert(C->have_alias_type(t_oop), "instance should have alias type");
1447
1448 // Do nothing here if Identity will find a value
1449 // (to avoid infinite chain of value phis generation).
1450 if (!phase->eqv(this, phase->apply_identity(this)))
1451 return NULL;
1452
1453 // Select Region to split through.
1454 Node* region;
1455 if (!base_is_phi) {
1456 assert(mem->is_Phi(), "sanity");
1457 region = mem->in(0);
1458 // Skip if the region dominates some control edge of the address.
1459 if (!MemNode::all_controls_dominate(address, region))
1460 return NULL;
1461 } else if (!mem->is_Phi()) {
1462 assert(base_is_phi, "sanity");
1463 region = base->in(0);
1464 // Skip if the region dominates some control edge of the memory.
1465 if (!MemNode::all_controls_dominate(mem, region))
1466 return NULL;
1467 } else if (base->in(0) != mem->in(0)) {
1468 assert(base_is_phi && mem->is_Phi(), "sanity");
1469 if (MemNode::all_controls_dominate(mem, base->in(0))) {
1470 region = base->in(0);
1471 } else if (MemNode::all_controls_dominate(address, mem->in(0))) {
1472 region = mem->in(0);
1473 } else {
1474 return NULL; // complex graph
1475 }
1476 } else {
1477 assert(base->in(0) == mem->in(0), "sanity");
1478 region = mem->in(0);
1479 }
1480
1481 const Type* this_type = this->bottom_type();
1482 int this_index = C->get_alias_index(t_oop);
1483 int this_offset = t_oop->offset();
1484 int this_iid = t_oop->instance_id();
1485 if (!t_oop->is_known_instance() && load_boxed_values) {
1486 // Use _idx of address base for boxed values.
1487 this_iid = base->_idx;
1488 }
1489 PhaseIterGVN* igvn = phase->is_IterGVN();
1490 Node* phi = new PhiNode(region, this_type, NULL, mem->_idx, this_iid, this_index, this_offset);
1491 for (uint i = 1; i < region->req(); i++) {
1492 Node* x;
1493 Node* the_clone = NULL;
1494 Node* in = region->in(i);
1495 if (region->is_CountedLoop() && region->as_Loop()->is_strip_mined() && i == LoopNode::EntryControl &&
1496 in != NULL && in->is_OuterStripMinedLoop()) {
1497 // No node should go in the outer strip mined loop
1498 in = in->in(LoopNode::EntryControl);
1499 }
1500 if (in == NULL || in == C->top()) {
1501 x = C->top(); // Dead path? Use a dead data op
1502 } else {
1503 x = this->clone(); // Else clone up the data op
1504 the_clone = x; // Remember for possible deletion.
1505 // Alter data node to use pre-phi inputs
1506 if (this->in(0) == region) {
1507 x->set_req(0, in);
1508 } else {
1509 x->set_req(0, NULL);
1510 }
1511 if (mem->is_Phi() && (mem->in(0) == region)) {
1512 x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone.
1513 }
1514 if (address->is_Phi() && address->in(0) == region) {
1515 x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone
1516 }
1517 if (base_is_phi && (base->in(0) == region)) {
1518 Node* base_x = base->in(i); // Clone address for loads from boxed objects.
1519 Node* adr_x = phase->transform(new AddPNode(base_x,base_x,address->in(AddPNode::Offset)));
1520 x->set_req(Address, adr_x);
1521 }
1522 }
1523 // Check for a 'win' on some paths
1524 const Type *t = x->Value(igvn);
1525
1526 bool singleton = t->singleton();
1527
1528 // See comments in PhaseIdealLoop::split_thru_phi().
1529 if (singleton && t == Type::TOP) {
1530 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1531 }
1532
1533 if (singleton) {
1534 x = igvn->makecon(t);
1535 } else {
1536 // We now call Identity to try to simplify the cloned node.
1537 // Note that some Identity methods call phase->type(this).
1538 // Make sure that the type array is big enough for
1539 // our new node, even though we may throw the node away.
1540 // (This tweaking with igvn only works because x is a new node.)
1541 igvn->set_type(x, t);
1542 // If x is a TypeNode, capture any more-precise type permanently into Node
1543 // otherwise it will be not updated during igvn->transform since
1544 // igvn->type(x) is set to x->Value() already.
1545 x->raise_bottom_type(t);
1546 Node *y = igvn->apply_identity(x);
1547 if (y != x) {
1548 x = y;
1549 } else {
1550 y = igvn->hash_find_insert(x);
1551 if (y) {
1552 x = y;
1553 } else {
1554 // Else x is a new node we are keeping
1555 // We do not need register_new_node_with_optimizer
1556 // because set_type has already been called.
1557 igvn->_worklist.push(x);
1558 }
1559 }
1560 }
1561 if (x != the_clone && the_clone != NULL) {
1562 igvn->remove_dead_node(the_clone);
1563 }
1564 phi->set_req(i, x);
1565 }
1566 // Record Phi
1567 igvn->register_new_node_with_optimizer(phi);
1568 return phi;
1569 }
1570
1571 //------------------------------Ideal------------------------------------------
1572 // If the load is from Field memory and the pointer is non-null, it might be possible to
1573 // zero out the control input.
1574 // If the offset is constant and the base is an object allocation,
1575 // try to hook me up to the exact initializing store.
1576 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1577 Node* p = MemNode::Ideal_common(phase, can_reshape);
1578 if (p) return (p == NodeSentinel) ? NULL : p;
1579
1580 Node* ctrl = in(MemNode::Control);
1581 Node* address = in(MemNode::Address);
1582 bool progress = false;
1583
1584 bool addr_mark = ((phase->type(address)->isa_oopptr() || phase->type(address)->isa_narrowoop()) &&
1585 phase->type(address)->is_ptr()->offset() == oopDesc::mark_offset_in_bytes());
1586
1587 // Skip up past a SafePoint control. Cannot do this for Stores because
1588 // pointer stores & cardmarks must stay on the same side of a SafePoint.
1589 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint &&
1590 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw &&
1591 !addr_mark ) {
1592 ctrl = ctrl->in(0);
1593 set_req(MemNode::Control,ctrl);
1594 progress = true;
1595 }
1596
1597 intptr_t ignore = 0;
1598 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1599 if (base != NULL
1600 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
1601 // Check for useless control edge in some common special cases
1602 if (in(MemNode::Control) != NULL
1603 && can_remove_control()
1604 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1605 && all_controls_dominate(base, phase->C->start())) {
1606 // A method-invariant, non-null address (constant or 'this' argument).
1607 set_req(MemNode::Control, NULL);
1608 progress = true;
1609 }
1610 }
1611
1612 Node* mem = in(MemNode::Memory);
1613 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1614
1615 if (can_reshape && (addr_t != NULL)) {
1616 // try to optimize our memory input
1617 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase);
1618 if (opt_mem != mem) {
1619 set_req(MemNode::Memory, opt_mem);
1620 if (phase->type( opt_mem ) == Type::TOP) return NULL;
1621 return this;
1622 }
1623 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1624 if ((t_oop != NULL) &&
1625 (t_oop->is_known_instance_field() ||
1626 t_oop->is_ptr_to_boxed_value())) {
1627 PhaseIterGVN *igvn = phase->is_IterGVN();
1628 if (igvn != NULL && igvn->_worklist.member(opt_mem)) {
1629 // Delay this transformation until memory Phi is processed.
1630 phase->is_IterGVN()->_worklist.push(this);
1631 return NULL;
1632 }
1633 // Split instance field load through Phi.
1634 Node* result = split_through_phi(phase);
1635 if (result != NULL) return result;
1636
1637 if (t_oop->is_ptr_to_boxed_value()) {
1638 Node* result = eliminate_autobox(phase);
1639 if (result != NULL) return result;
1640 }
1641 }
1642 }
1643
1644 // Is there a dominating load that loads the same value? Leave
1645 // anything that is not a load of a field/array element (like
1646 // barriers etc.) alone
1647 if (in(0) != NULL && !adr_type()->isa_rawptr() && can_reshape) {
1648 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) {
1649 Node *use = mem->fast_out(i);
1650 if (use != this &&
1651 use->Opcode() == Opcode() &&
1652 use->in(0) != NULL &&
1653 use->in(0) != in(0) &&
1654 use->in(Address) == in(Address)) {
1655 Node* ctl = in(0);
1656 for (int i = 0; i < 10 && ctl != NULL; i++) {
1657 ctl = IfNode::up_one_dom(ctl);
1658 if (ctl == use->in(0)) {
1659 set_req(0, use->in(0));
1660 return this;
1661 }
1662 }
1663 }
1664 }
1665 }
1666
1667 // Check for prior store with a different base or offset; make Load
1668 // independent. Skip through any number of them. Bail out if the stores
1669 // are in an endless dead cycle and report no progress. This is a key
1670 // transform for Reflection. However, if after skipping through the Stores
1671 // we can't then fold up against a prior store do NOT do the transform as
1672 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
1673 // array memory alive twice: once for the hoisted Load and again after the
1674 // bypassed Store. This situation only works if EVERYBODY who does
1675 // anti-dependence work knows how to bypass. I.e. we need all
1676 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
1677 // the alias index stuff. So instead, peek through Stores and IFF we can
1678 // fold up, do so.
1679 Node* prev_mem = find_previous_store(phase);
1680 if (prev_mem != NULL) {
1681 Node* value = can_see_arraycopy_value(prev_mem, phase);
1682 if (value != NULL) {
1683 return value;
1684 }
1685 }
1686 // Steps (a), (b): Walk past independent stores to find an exact match.
1687 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) {
1688 // (c) See if we can fold up on the spot, but don't fold up here.
1689 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
1690 // just return a prior value, which is done by Identity calls.
1691 if (can_see_stored_value(prev_mem, phase)) {
1692 // Make ready for step (d):
1693 set_req(MemNode::Memory, prev_mem);
1694 return this;
1695 }
1696 }
1697
1698 return progress ? this : NULL;
1699 }
1700
1701 // Helper to recognize certain Klass fields which are invariant across
1702 // some group of array types (e.g., int[] or all T[] where T < Object).
1703 const Type*
1704 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1705 ciKlass* klass) const {
1706 if (tkls->offset() == in_bytes(Klass::modifier_flags_offset())) {
1707 // The field is Klass::_modifier_flags. Return its (constant) value.
1708 // (Folds up the 2nd indirection in aClassConstant.getModifiers().)
1709 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags");
1710 return TypeInt::make(klass->modifier_flags());
1711 }
1712 if (tkls->offset() == in_bytes(Klass::access_flags_offset())) {
1713 // The field is Klass::_access_flags. Return its (constant) value.
1714 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1715 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags");
1716 return TypeInt::make(klass->access_flags());
1717 }
1718 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) {
1719 // The field is Klass::_layout_helper. Return its constant value if known.
1720 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper");
1721 return TypeInt::make(klass->layout_helper());
1722 }
1723
1724 // No match.
1725 return NULL;
1726 }
1727
1728 //------------------------------Value-----------------------------------------
1729 const Type* LoadNode::Value(PhaseGVN* phase) const {
1730 // Either input is TOP ==> the result is TOP
1731 Node* mem = in(MemNode::Memory);
1732 const Type *t1 = phase->type(mem);
1733 if (t1 == Type::TOP) return Type::TOP;
1734 Node* adr = in(MemNode::Address);
1735 const TypePtr* tp = phase->type(adr)->isa_ptr();
1736 if (tp == NULL || tp->empty()) return Type::TOP;
1737 int off = tp->offset();
1738 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
1739 Compile* C = phase->C;
1740
1741 // Try to guess loaded type from pointer type
1742 if (tp->isa_aryptr()) {
1743 const TypeAryPtr* ary = tp->is_aryptr();
1744 const Type* t = ary->elem();
1745
1746 // Determine whether the reference is beyond the header or not, by comparing
1747 // the offset against the offset of the start of the array's data.
1748 // Different array types begin at slightly different offsets (12 vs. 16).
1749 // We choose T_BYTE as an example base type that is least restrictive
1750 // as to alignment, which will therefore produce the smallest
1751 // possible base offset.
1752 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
1753 const bool off_beyond_header = ((uint)off >= (uint)min_base_off);
1754
1755 // Try to constant-fold a stable array element.
1756 if (FoldStableValues && !is_mismatched_access() && ary->is_stable()) {
1757 // Make sure the reference is not into the header and the offset is constant
1758 ciObject* aobj = ary->const_oop();
1759 if (aobj != NULL && off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) {
1760 int stable_dimension = (ary->stable_dimension() > 0 ? ary->stable_dimension() - 1 : 0);
1761 const Type* con_type = Type::make_constant_from_array_element(aobj->as_array(), off,
1762 stable_dimension,
1763 memory_type(), is_unsigned());
1764 if (con_type != NULL) {
1765 return con_type;
1766 }
1767 }
1768 }
1769
1770 // Don't do this for integer types. There is only potential profit if
1771 // the element type t is lower than _type; that is, for int types, if _type is
1772 // more restrictive than t. This only happens here if one is short and the other
1773 // char (both 16 bits), and in those cases we've made an intentional decision
1774 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
1775 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
1776 //
1777 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
1778 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
1779 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
1780 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
1781 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
1782 // In fact, that could have been the original type of p1, and p1 could have
1783 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
1784 // expression (LShiftL quux 3) independently optimized to the constant 8.
1785 if ((t->isa_int() == NULL) && (t->isa_long() == NULL)
1786 && (_type->isa_vect() == NULL)
1787 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
1788 // t might actually be lower than _type, if _type is a unique
1789 // concrete subclass of abstract class t.
1790 if (off_beyond_header) { // is the offset beyond the header?
1791 const Type* jt = t->join_speculative(_type);
1792 // In any case, do not allow the join, per se, to empty out the type.
1793 if (jt->empty() && !t->empty()) {
1794 // This can happen if a interface-typed array narrows to a class type.
1795 jt = _type;
1796 }
1797 #ifdef ASSERT
1798 if (phase->C->eliminate_boxing() && adr->is_AddP()) {
1799 // The pointers in the autobox arrays are always non-null
1800 Node* base = adr->in(AddPNode::Base);
1801 if ((base != NULL) && base->is_DecodeN()) {
1802 // Get LoadN node which loads IntegerCache.cache field
1803 base = base->in(1);
1804 }
1805 if ((base != NULL) && base->is_Con()) {
1806 const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr();
1807 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1808 // It could be narrow oop
1809 assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity");
1810 }
1811 }
1812 }
1813 #endif
1814 return jt;
1815 }
1816 }
1817 } else if (tp->base() == Type::InstPtr) {
1818 assert( off != Type::OffsetBot ||
1819 // arrays can be cast to Objects
1820 tp->is_oopptr()->klass()->is_java_lang_Object() ||
1821 // unsafe field access may not have a constant offset
1822 C->has_unsafe_access(),
1823 "Field accesses must be precise" );
1824 // For oop loads, we expect the _type to be precise.
1825
1826 // Optimize loads from constant fields.
1827 const TypeInstPtr* tinst = tp->is_instptr();
1828 ciObject* const_oop = tinst->const_oop();
1829 if (!is_mismatched_access() && off != Type::OffsetBot && const_oop != NULL && const_oop->is_instance()) {
1830 const Type* con_type = Type::make_constant_from_field(const_oop->as_instance(), off, is_unsigned(), memory_type());
1831 if (con_type != NULL) {
1832 return con_type;
1833 }
1834 }
1835 } else if (tp->base() == Type::KlassPtr) {
1836 assert( off != Type::OffsetBot ||
1837 // arrays can be cast to Objects
1838 tp->is_klassptr()->klass()->is_java_lang_Object() ||
1839 // also allow array-loading from the primary supertype
1840 // array during subtype checks
1841 Opcode() == Op_LoadKlass,
1842 "Field accesses must be precise" );
1843 // For klass/static loads, we expect the _type to be precise
1844 } else if (tp->base() == Type::RawPtr && adr->is_Load() && off == 0) {
1845 /* With mirrors being an indirect in the Klass*
1846 * the VM is now using two loads. LoadKlass(LoadP(LoadP(Klass, mirror_offset), zero_offset))
1847 * The LoadP from the Klass has a RawPtr type (see LibraryCallKit::load_mirror_from_klass).
1848 *
1849 * So check the type and klass of the node before the LoadP.
1850 */
1851 Node* adr2 = adr->in(MemNode::Address);
1852 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
1853 if (tkls != NULL && !StressReflectiveCode) {
1854 ciKlass* klass = tkls->klass();
1855 if (klass->is_loaded() && tkls->klass_is_exact() && tkls->offset() == in_bytes(Klass::java_mirror_offset())) {
1856 assert(adr->Opcode() == Op_LoadP, "must load an oop from _java_mirror");
1857 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
1858 return TypeInstPtr::make(klass->java_mirror());
1859 }
1860 }
1861 }
1862
1863 const TypeKlassPtr *tkls = tp->isa_klassptr();
1864 if (tkls != NULL && !StressReflectiveCode) {
1865 ciKlass* klass = tkls->klass();
1866 if (klass->is_loaded() && tkls->klass_is_exact()) {
1867 // We are loading a field from a Klass metaobject whose identity
1868 // is known at compile time (the type is "exact" or "precise").
1869 // Check for fields we know are maintained as constants by the VM.
1870 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) {
1871 // The field is Klass::_super_check_offset. Return its (constant) value.
1872 // (Folds up type checking code.)
1873 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
1874 return TypeInt::make(klass->super_check_offset());
1875 }
1876 // Compute index into primary_supers array
1877 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1878 // Check for overflowing; use unsigned compare to handle the negative case.
1879 if( depth < ciKlass::primary_super_limit() ) {
1880 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1881 // (Folds up type checking code.)
1882 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1883 ciKlass *ss = klass->super_of_depth(depth);
1884 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1885 }
1886 const Type* aift = load_array_final_field(tkls, klass);
1887 if (aift != NULL) return aift;
1888 }
1889
1890 // We can still check if we are loading from the primary_supers array at a
1891 // shallow enough depth. Even though the klass is not exact, entries less
1892 // than or equal to its super depth are correct.
1893 if (klass->is_loaded() ) {
1894 ciType *inner = klass;
1895 while( inner->is_obj_array_klass() )
1896 inner = inner->as_obj_array_klass()->base_element_type();
1897 if( inner->is_instance_klass() &&
1898 !inner->as_instance_klass()->flags().is_interface() ) {
1899 // Compute index into primary_supers array
1900 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1901 // Check for overflowing; use unsigned compare to handle the negative case.
1902 if( depth < ciKlass::primary_super_limit() &&
1903 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case
1904 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1905 // (Folds up type checking code.)
1906 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1907 ciKlass *ss = klass->super_of_depth(depth);
1908 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1909 }
1910 }
1911 }
1912
1913 // If the type is enough to determine that the thing is not an array,
1914 // we can give the layout_helper a positive interval type.
1915 // This will help short-circuit some reflective code.
1916 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())
1917 && !klass->is_array_klass() // not directly typed as an array
1918 && !klass->is_interface() // specifically not Serializable & Cloneable
1919 && !klass->is_java_lang_Object() // not the supertype of all T[]
1920 ) {
1921 // Note: When interfaces are reliable, we can narrow the interface
1922 // test to (klass != Serializable && klass != Cloneable).
1923 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
1924 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
1925 // The key property of this type is that it folds up tests
1926 // for array-ness, since it proves that the layout_helper is positive.
1927 // Thus, a generic value like the basic object layout helper works fine.
1928 return TypeInt::make(min_size, max_jint, Type::WidenMin);
1929 }
1930 }
1931
1932 // If we are loading from a freshly-allocated object, produce a zero,
1933 // if the load is provably beyond the header of the object.
1934 // (Also allow a variable load from a fresh array to produce zero.)
1935 const TypeOopPtr *tinst = tp->isa_oopptr();
1936 bool is_instance = (tinst != NULL) && tinst->is_known_instance_field();
1937 bool is_boxed_value = (tinst != NULL) && tinst->is_ptr_to_boxed_value();
1938 if (ReduceFieldZeroing || is_instance || is_boxed_value) {
1939 Node* value = can_see_stored_value(mem,phase);
1940 if (value != NULL && value->is_Con()) {
1941 assert(value->bottom_type()->higher_equal(_type),"sanity");
1942 return value->bottom_type();
1943 }
1944 }
1945
1946 if (is_instance) {
1947 // If we have an instance type and our memory input is the
1948 // programs's initial memory state, there is no matching store,
1949 // so just return a zero of the appropriate type
1950 Node *mem = in(MemNode::Memory);
1951 if (mem->is_Parm() && mem->in(0)->is_Start()) {
1952 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
1953 return Type::get_zero_type(_type->basic_type());
1954 }
1955 }
1956 return _type;
1957 }
1958
1959 //------------------------------match_edge-------------------------------------
1960 // Do we Match on this edge index or not? Match only the address.
1961 uint LoadNode::match_edge(uint idx) const {
1962 return idx == MemNode::Address;
1963 }
1964
1965 //--------------------------LoadBNode::Ideal--------------------------------------
1966 //
1967 // If the previous store is to the same address as this load,
1968 // and the value stored was larger than a byte, replace this load
1969 // with the value stored truncated to a byte. If no truncation is
1970 // needed, the replacement is done in LoadNode::Identity().
1971 //
1972 Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1973 Node* mem = in(MemNode::Memory);
1974 Node* value = can_see_stored_value(mem,phase);
1975 if( value && !phase->type(value)->higher_equal( _type ) ) {
1976 Node *result = phase->transform( new LShiftINode(value, phase->intcon(24)) );
1977 return new RShiftINode(result, phase->intcon(24));
1978 }
1979 // Identity call will handle the case where truncation is not needed.
1980 return LoadNode::Ideal(phase, can_reshape);
1981 }
1982
1983 const Type* LoadBNode::Value(PhaseGVN* phase) const {
1984 Node* mem = in(MemNode::Memory);
1985 Node* value = can_see_stored_value(mem,phase);
1986 if (value != NULL && value->is_Con() &&
1987 !value->bottom_type()->higher_equal(_type)) {
1988 // If the input to the store does not fit with the load's result type,
1989 // it must be truncated. We can't delay until Ideal call since
1990 // a singleton Value is needed for split_thru_phi optimization.
1991 int con = value->get_int();
1992 return TypeInt::make((con << 24) >> 24);
1993 }
1994 return LoadNode::Value(phase);
1995 }
1996
1997 //--------------------------LoadUBNode::Ideal-------------------------------------
1998 //
1999 // If the previous store is to the same address as this load,
2000 // and the value stored was larger than a byte, replace this load
2001 // with the value stored truncated to a byte. If no truncation is
2002 // needed, the replacement is done in LoadNode::Identity().
2003 //
2004 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2005 Node* mem = in(MemNode::Memory);
2006 Node* value = can_see_stored_value(mem, phase);
2007 if (value && !phase->type(value)->higher_equal(_type))
2008 return new AndINode(value, phase->intcon(0xFF));
2009 // Identity call will handle the case where truncation is not needed.
2010 return LoadNode::Ideal(phase, can_reshape);
2011 }
2012
2013 const Type* LoadUBNode::Value(PhaseGVN* phase) const {
2014 Node* mem = in(MemNode::Memory);
2015 Node* value = can_see_stored_value(mem,phase);
2016 if (value != NULL && value->is_Con() &&
2017 !value->bottom_type()->higher_equal(_type)) {
2018 // If the input to the store does not fit with the load's result type,
2019 // it must be truncated. We can't delay until Ideal call since
2020 // a singleton Value is needed for split_thru_phi optimization.
2021 int con = value->get_int();
2022 return TypeInt::make(con & 0xFF);
2023 }
2024 return LoadNode::Value(phase);
2025 }
2026
2027 //--------------------------LoadUSNode::Ideal-------------------------------------
2028 //
2029 // If the previous store is to the same address as this load,
2030 // and the value stored was larger than a char, replace this load
2031 // with the value stored truncated to a char. If no truncation is
2032 // needed, the replacement is done in LoadNode::Identity().
2033 //
2034 Node *LoadUSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2035 Node* mem = in(MemNode::Memory);
2036 Node* value = can_see_stored_value(mem,phase);
2037 if( value && !phase->type(value)->higher_equal( _type ) )
2038 return new AndINode(value,phase->intcon(0xFFFF));
2039 // Identity call will handle the case where truncation is not needed.
2040 return LoadNode::Ideal(phase, can_reshape);
2041 }
2042
2043 const Type* LoadUSNode::Value(PhaseGVN* phase) const {
2044 Node* mem = in(MemNode::Memory);
2045 Node* value = can_see_stored_value(mem,phase);
2046 if (value != NULL && value->is_Con() &&
2047 !value->bottom_type()->higher_equal(_type)) {
2048 // If the input to the store does not fit with the load's result type,
2049 // it must be truncated. We can't delay until Ideal call since
2050 // a singleton Value is needed for split_thru_phi optimization.
2051 int con = value->get_int();
2052 return TypeInt::make(con & 0xFFFF);
2053 }
2054 return LoadNode::Value(phase);
2055 }
2056
2057 //--------------------------LoadSNode::Ideal--------------------------------------
2058 //
2059 // If the previous store is to the same address as this load,
2060 // and the value stored was larger than a short, replace this load
2061 // with the value stored truncated to a short. If no truncation is
2062 // needed, the replacement is done in LoadNode::Identity().
2063 //
2064 Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2065 Node* mem = in(MemNode::Memory);
2066 Node* value = can_see_stored_value(mem,phase);
2067 if( value && !phase->type(value)->higher_equal( _type ) ) {
2068 Node *result = phase->transform( new LShiftINode(value, phase->intcon(16)) );
2069 return new RShiftINode(result, phase->intcon(16));
2070 }
2071 // Identity call will handle the case where truncation is not needed.
2072 return LoadNode::Ideal(phase, can_reshape);
2073 }
2074
2075 const Type* LoadSNode::Value(PhaseGVN* phase) const {
2076 Node* mem = in(MemNode::Memory);
2077 Node* value = can_see_stored_value(mem,phase);
2078 if (value != NULL && value->is_Con() &&
2079 !value->bottom_type()->higher_equal(_type)) {
2080 // If the input to the store does not fit with the load's result type,
2081 // it must be truncated. We can't delay until Ideal call since
2082 // a singleton Value is needed for split_thru_phi optimization.
2083 int con = value->get_int();
2084 return TypeInt::make((con << 16) >> 16);
2085 }
2086 return LoadNode::Value(phase);
2087 }
2088
2089 //=============================================================================
2090 //----------------------------LoadKlassNode::make------------------------------
2091 // Polymorphic factory method:
2092 Node* LoadKlassNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* at, const TypeKlassPtr* tk) {
2093 // sanity check the alias category against the created node type
2094 const TypePtr *adr_type = adr->bottom_type()->isa_ptr();
2095 assert(adr_type != NULL, "expecting TypeKlassPtr");
2096 #ifdef _LP64
2097 if (adr_type->is_ptr_to_narrowklass()) {
2098 assert(UseCompressedClassPointers, "no compressed klasses");
2099 Node* load_klass = gvn.transform(new LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowklass(), MemNode::unordered));
2100 return new DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr());
2101 }
2102 #endif
2103 assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
2104 return new LoadKlassNode(ctl, mem, adr, at, tk, MemNode::unordered);
2105 }
2106
2107 //------------------------------Value------------------------------------------
2108 const Type* LoadKlassNode::Value(PhaseGVN* phase) const {
2109 return klass_value_common(phase);
2110 }
2111
2112 // In most cases, LoadKlassNode does not have the control input set. If the control
2113 // input is set, it must not be removed (by LoadNode::Ideal()).
2114 bool LoadKlassNode::can_remove_control() const {
2115 return false;
2116 }
2117
2118 const Type* LoadNode::klass_value_common(PhaseGVN* phase) const {
2119 // Either input is TOP ==> the result is TOP
2120 const Type *t1 = phase->type( in(MemNode::Memory) );
2121 if (t1 == Type::TOP) return Type::TOP;
2122 Node *adr = in(MemNode::Address);
2123 const Type *t2 = phase->type( adr );
2124 if (t2 == Type::TOP) return Type::TOP;
2125 const TypePtr *tp = t2->is_ptr();
2126 if (TypePtr::above_centerline(tp->ptr()) ||
2127 tp->ptr() == TypePtr::Null) return Type::TOP;
2128
2129 // Return a more precise klass, if possible
2130 const TypeInstPtr *tinst = tp->isa_instptr();
2131 if (tinst != NULL) {
2132 ciInstanceKlass* ik = tinst->klass()->as_instance_klass();
2133 int offset = tinst->offset();
2134 if (ik == phase->C->env()->Class_klass()
2135 && (offset == java_lang_Class::klass_offset_in_bytes() ||
2136 offset == java_lang_Class::array_klass_offset_in_bytes())) {
2137 // We are loading a special hidden field from a Class mirror object,
2138 // the field which points to the VM's Klass metaobject.
2139 ciType* t = tinst->java_mirror_type();
2140 // java_mirror_type returns non-null for compile-time Class constants.
2141 if (t != NULL) {
2142 // constant oop => constant klass
2143 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
2144 if (t->is_void()) {
2145 // We cannot create a void array. Since void is a primitive type return null
2146 // klass. Users of this result need to do a null check on the returned klass.
2147 return TypePtr::NULL_PTR;
2148 }
2149 return TypeKlassPtr::make(ciArrayKlass::make(t));
2150 }
2151 if (!t->is_klass()) {
2152 // a primitive Class (e.g., int.class) has NULL for a klass field
2153 return TypePtr::NULL_PTR;
2154 }
2155 // (Folds up the 1st indirection in aClassConstant.getModifiers().)
2156 return TypeKlassPtr::make(t->as_klass());
2157 }
2158 // non-constant mirror, so we can't tell what's going on
2159 }
2160 if( !ik->is_loaded() )
2161 return _type; // Bail out if not loaded
2162 if (offset == oopDesc::klass_offset_in_bytes()) {
2163 if (tinst->klass_is_exact()) {
2164 return TypeKlassPtr::make(ik);
2165 }
2166 // See if we can become precise: no subklasses and no interface
2167 // (Note: We need to support verified interfaces.)
2168 if (!ik->is_interface() && !ik->has_subklass()) {
2169 //assert(!UseExactTypes, "this code should be useless with exact types");
2170 // Add a dependence; if any subclass added we need to recompile
2171 if (!ik->is_final()) {
2172 // %%% should use stronger assert_unique_concrete_subtype instead
2173 phase->C->dependencies()->assert_leaf_type(ik);
2174 }
2175 // Return precise klass
2176 return TypeKlassPtr::make(ik);
2177 }
2178
2179 // Return root of possible klass
2180 return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/);
2181 }
2182 }
2183
2184 // Check for loading klass from an array
2185 const TypeAryPtr *tary = tp->isa_aryptr();
2186 if( tary != NULL ) {
2187 ciKlass *tary_klass = tary->klass();
2188 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP
2189 && tary->offset() == oopDesc::klass_offset_in_bytes()) {
2190 if (tary->klass_is_exact()) {
2191 return TypeKlassPtr::make(tary_klass);
2192 }
2193 ciArrayKlass *ak = tary->klass()->as_array_klass();
2194 // If the klass is an object array, we defer the question to the
2195 // array component klass.
2196 if( ak->is_obj_array_klass() ) {
2197 assert( ak->is_loaded(), "" );
2198 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass();
2199 if( base_k->is_loaded() && base_k->is_instance_klass() ) {
2200 ciInstanceKlass* ik = base_k->as_instance_klass();
2201 // See if we can become precise: no subklasses and no interface
2202 if (!ik->is_interface() && !ik->has_subklass()) {
2203 //assert(!UseExactTypes, "this code should be useless with exact types");
2204 // Add a dependence; if any subclass added we need to recompile
2205 if (!ik->is_final()) {
2206 phase->C->dependencies()->assert_leaf_type(ik);
2207 }
2208 // Return precise array klass
2209 return TypeKlassPtr::make(ak);
2210 }
2211 }
2212 return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/);
2213 } else { // Found a type-array?
2214 //assert(!UseExactTypes, "this code should be useless with exact types");
2215 assert( ak->is_type_array_klass(), "" );
2216 return TypeKlassPtr::make(ak); // These are always precise
2217 }
2218 }
2219 }
2220
2221 // Check for loading klass from an array klass
2222 const TypeKlassPtr *tkls = tp->isa_klassptr();
2223 if (tkls != NULL && !StressReflectiveCode) {
2224 ciKlass* klass = tkls->klass();
2225 if( !klass->is_loaded() )
2226 return _type; // Bail out if not loaded
2227 if( klass->is_obj_array_klass() &&
2228 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) {
2229 ciKlass* elem = klass->as_obj_array_klass()->element_klass();
2230 // // Always returning precise element type is incorrect,
2231 // // e.g., element type could be object and array may contain strings
2232 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
2233
2234 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
2235 // according to the element type's subclassing.
2236 return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/);
2237 }
2238 if( klass->is_instance_klass() && tkls->klass_is_exact() &&
2239 tkls->offset() == in_bytes(Klass::super_offset())) {
2240 ciKlass* sup = klass->as_instance_klass()->super();
2241 // The field is Klass::_super. Return its (constant) value.
2242 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
2243 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR;
2244 }
2245 }
2246
2247 // Bailout case
2248 return LoadNode::Value(phase);
2249 }
2250
2251 //------------------------------Identity---------------------------------------
2252 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
2253 // Also feed through the klass in Allocate(...klass...)._klass.
2254 Node* LoadKlassNode::Identity(PhaseGVN* phase) {
2255 return klass_identity_common(phase);
2256 }
2257
2258 Node* LoadNode::klass_identity_common(PhaseGVN* phase) {
2259 Node* x = LoadNode::Identity(phase);
2260 if (x != this) return x;
2261
2262 // Take apart the address into an oop and and offset.
2263 // Return 'this' if we cannot.
2264 Node* adr = in(MemNode::Address);
2265 intptr_t offset = 0;
2266 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2267 if (base == NULL) return this;
2268 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
2269 if (toop == NULL) return this;
2270
2271 // Step over potential GC barrier for OopHandle resolve
2272 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
2273 if (bs->is_gc_barrier_node(base)) {
2274 base = bs->step_over_gc_barrier(base);
2275 }
2276
2277 // We can fetch the klass directly through an AllocateNode.
2278 // This works even if the klass is not constant (clone or newArray).
2279 if (offset == oopDesc::klass_offset_in_bytes()) {
2280 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
2281 if (allocated_klass != NULL) {
2282 return allocated_klass;
2283 }
2284 }
2285
2286 // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*.
2287 // See inline_native_Class_query for occurrences of these patterns.
2288 // Java Example: x.getClass().isAssignableFrom(y)
2289 //
2290 // This improves reflective code, often making the Class
2291 // mirror go completely dead. (Current exception: Class
2292 // mirrors may appear in debug info, but we could clean them out by
2293 // introducing a new debug info operator for Klass.java_mirror).
2294
2295 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass()
2296 && offset == java_lang_Class::klass_offset_in_bytes()) {
2297 if (base->is_Load()) {
2298 Node* base2 = base->in(MemNode::Address);
2299 if (base2->is_Load()) { /* direct load of a load which is the OopHandle */
2300 Node* adr2 = base2->in(MemNode::Address);
2301 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2302 if (tkls != NULL && !tkls->empty()
2303 && (tkls->klass()->is_instance_klass() ||
2304 tkls->klass()->is_array_klass())
2305 && adr2->is_AddP()
2306 ) {
2307 int mirror_field = in_bytes(Klass::java_mirror_offset());
2308 if (tkls->offset() == mirror_field) {
2309 return adr2->in(AddPNode::Base);
2310 }
2311 }
2312 }
2313 }
2314 }
2315
2316 return this;
2317 }
2318
2319
2320 //------------------------------Value------------------------------------------
2321 const Type* LoadNKlassNode::Value(PhaseGVN* phase) const {
2322 const Type *t = klass_value_common(phase);
2323 if (t == Type::TOP)
2324 return t;
2325
2326 return t->make_narrowklass();
2327 }
2328
2329 //------------------------------Identity---------------------------------------
2330 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
2331 // Also feed through the klass in Allocate(...klass...)._klass.
2332 Node* LoadNKlassNode::Identity(PhaseGVN* phase) {
2333 Node *x = klass_identity_common(phase);
2334
2335 const Type *t = phase->type( x );
2336 if( t == Type::TOP ) return x;
2337 if( t->isa_narrowklass()) return x;
2338 assert (!t->isa_narrowoop(), "no narrow oop here");
2339
2340 return phase->transform(new EncodePKlassNode(x, t->make_narrowklass()));
2341 }
2342
2343 //------------------------------Value-----------------------------------------
2344 const Type* LoadRangeNode::Value(PhaseGVN* phase) const {
2345 // Either input is TOP ==> the result is TOP
2346 const Type *t1 = phase->type( in(MemNode::Memory) );
2347 if( t1 == Type::TOP ) return Type::TOP;
2348 Node *adr = in(MemNode::Address);
2349 const Type *t2 = phase->type( adr );
2350 if( t2 == Type::TOP ) return Type::TOP;
2351 const TypePtr *tp = t2->is_ptr();
2352 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
2353 const TypeAryPtr *tap = tp->isa_aryptr();
2354 if( !tap ) return _type;
2355 return tap->size();
2356 }
2357
2358 //-------------------------------Ideal---------------------------------------
2359 // Feed through the length in AllocateArray(...length...)._length.
2360 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2361 Node* p = MemNode::Ideal_common(phase, can_reshape);
2362 if (p) return (p == NodeSentinel) ? NULL : p;
2363
2364 // Take apart the address into an oop and and offset.
2365 // Return 'this' if we cannot.
2366 Node* adr = in(MemNode::Address);
2367 intptr_t offset = 0;
2368 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2369 if (base == NULL) return NULL;
2370 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2371 if (tary == NULL) return NULL;
2372
2373 // We can fetch the length directly through an AllocateArrayNode.
2374 // This works even if the length is not constant (clone or newArray).
2375 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2376 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2377 if (alloc != NULL) {
2378 Node* allocated_length = alloc->Ideal_length();
2379 Node* len = alloc->make_ideal_length(tary, phase);
2380 if (allocated_length != len) {
2381 // New CastII improves on this.
2382 return len;
2383 }
2384 }
2385 }
2386
2387 return NULL;
2388 }
2389
2390 //------------------------------Identity---------------------------------------
2391 // Feed through the length in AllocateArray(...length...)._length.
2392 Node* LoadRangeNode::Identity(PhaseGVN* phase) {
2393 Node* x = LoadINode::Identity(phase);
2394 if (x != this) return x;
2395
2396 // Take apart the address into an oop and and offset.
2397 // Return 'this' if we cannot.
2398 Node* adr = in(MemNode::Address);
2399 intptr_t offset = 0;
2400 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2401 if (base == NULL) return this;
2402 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2403 if (tary == NULL) return this;
2404
2405 // We can fetch the length directly through an AllocateArrayNode.
2406 // This works even if the length is not constant (clone or newArray).
2407 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2408 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2409 if (alloc != NULL) {
2410 Node* allocated_length = alloc->Ideal_length();
2411 // Do not allow make_ideal_length to allocate a CastII node.
2412 Node* len = alloc->make_ideal_length(tary, phase, false);
2413 if (allocated_length == len) {
2414 // Return allocated_length only if it would not be improved by a CastII.
2415 return allocated_length;
2416 }
2417 }
2418 }
2419
2420 return this;
2421
2422 }
2423
2424 //=============================================================================
2425 //---------------------------StoreNode::make-----------------------------------
2426 // Polymorphic factory method:
2427 StoreNode* StoreNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt, MemOrd mo) {
2428 assert((mo == unordered || mo == release), "unexpected");
2429 Compile* C = gvn.C;
2430 assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2431 ctl != NULL, "raw memory operations should have control edge");
2432
2433 switch (bt) {
2434 case T_BOOLEAN: val = gvn.transform(new AndINode(val, gvn.intcon(0x1))); // Fall through to T_BYTE case
2435 case T_BYTE: return new StoreBNode(ctl, mem, adr, adr_type, val, mo);
2436 case T_INT: return new StoreINode(ctl, mem, adr, adr_type, val, mo);
2437 case T_CHAR:
2438 case T_SHORT: return new StoreCNode(ctl, mem, adr, adr_type, val, mo);
2439 case T_LONG: return new StoreLNode(ctl, mem, adr, adr_type, val, mo);
2440 case T_FLOAT: return new StoreFNode(ctl, mem, adr, adr_type, val, mo);
2441 case T_DOUBLE: return new StoreDNode(ctl, mem, adr, adr_type, val, mo);
2442 case T_METADATA:
2443 case T_ADDRESS:
2444 case T_OBJECT:
2445 #ifdef _LP64
2446 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
2447 val = gvn.transform(new EncodePNode(val, val->bottom_type()->make_narrowoop()));
2448 return new StoreNNode(ctl, mem, adr, adr_type, val, mo);
2449 } else if (adr->bottom_type()->is_ptr_to_narrowklass() ||
2450 (UseCompressedClassPointers && val->bottom_type()->isa_klassptr() &&
2451 adr->bottom_type()->isa_rawptr())) {
2452 val = gvn.transform(new EncodePKlassNode(val, val->bottom_type()->make_narrowklass()));
2453 return new StoreNKlassNode(ctl, mem, adr, adr_type, val, mo);
2454 }
2455 #endif
2456 {
2457 return new StorePNode(ctl, mem, adr, adr_type, val, mo);
2458 }
2459 default:
2460 ShouldNotReachHere();
2461 return (StoreNode*)NULL;
2462 }
2463 }
2464
2465 StoreLNode* StoreLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
2466 bool require_atomic = true;
2467 return new StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
2468 }
2469
2470 StoreDNode* StoreDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
2471 bool require_atomic = true;
2472 return new StoreDNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
2473 }
2474
2475
2476 //--------------------------bottom_type----------------------------------------
2477 const Type *StoreNode::bottom_type() const {
2478 return Type::MEMORY;
2479 }
2480
2481 //------------------------------hash-------------------------------------------
2482 uint StoreNode::hash() const {
2483 // unroll addition of interesting fields
2484 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2485
2486 // Since they are not commoned, do not hash them:
2487 return NO_HASH;
2488 }
2489
2490 //------------------------------Ideal------------------------------------------
2491 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
2492 // When a store immediately follows a relevant allocation/initialization,
2493 // try to capture it into the initialization, or hoist it above.
2494 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2495 Node* p = MemNode::Ideal_common(phase, can_reshape);
2496 if (p) return (p == NodeSentinel) ? NULL : p;
2497
2498 Node* mem = in(MemNode::Memory);
2499 Node* address = in(MemNode::Address);
2500 // Back-to-back stores to same address? Fold em up. Generally
2501 // unsafe if I have intervening uses... Also disallowed for StoreCM
2502 // since they must follow each StoreP operation. Redundant StoreCMs
2503 // are eliminated just before matching in final_graph_reshape.
2504 {
2505 Node* st = mem;
2506 // If Store 'st' has more than one use, we cannot fold 'st' away.
2507 // For example, 'st' might be the final state at a conditional
2508 // return. Or, 'st' might be used by some node which is live at
2509 // the same time 'st' is live, which might be unschedulable. So,
2510 // require exactly ONE user until such time as we clone 'mem' for
2511 // each of 'mem's uses (thus making the exactly-1-user-rule hold
2512 // true).
2513 while (st->is_Store() && st->outcnt() == 1 && st->Opcode() != Op_StoreCM) {
2514 // Looking at a dead closed cycle of memory?
2515 assert(st != st->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
2516 assert(Opcode() == st->Opcode() ||
2517 st->Opcode() == Op_StoreVector ||
2518 Opcode() == Op_StoreVector ||
2519 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw ||
2520 (Opcode() == Op_StoreL && st->Opcode() == Op_StoreI) || // expanded ClearArrayNode
2521 (Opcode() == Op_StoreI && st->Opcode() == Op_StoreL) || // initialization by arraycopy
2522 (is_mismatched_access() || st->as_Store()->is_mismatched_access()),
2523 "no mismatched stores, except on raw memory: %s %s", NodeClassNames[Opcode()], NodeClassNames[st->Opcode()]);
2524
2525 if (st->in(MemNode::Address)->eqv_uncast(address) &&
2526 st->as_Store()->memory_size() <= this->memory_size()) {
2527 Node* use = st->raw_out(0);
2528 phase->igvn_rehash_node_delayed(use);
2529 if (can_reshape) {
2530 use->set_req_X(MemNode::Memory, st->in(MemNode::Memory), phase->is_IterGVN());
2531 } else {
2532 // It's OK to do this in the parser, since DU info is always accurate,
2533 // and the parser always refers to nodes via SafePointNode maps.
2534 use->set_req(MemNode::Memory, st->in(MemNode::Memory));
2535 }
2536 return this;
2537 }
2538 st = st->in(MemNode::Memory);
2539 }
2540 }
2541
2542
2543 // Capture an unaliased, unconditional, simple store into an initializer.
2544 // Or, if it is independent of the allocation, hoist it above the allocation.
2545 if (ReduceFieldZeroing && /*can_reshape &&*/
2546 mem->is_Proj() && mem->in(0)->is_Initialize()) {
2547 InitializeNode* init = mem->in(0)->as_Initialize();
2548 intptr_t offset = init->can_capture_store(this, phase, can_reshape);
2549 if (offset > 0) {
2550 Node* moved = init->capture_store(this, offset, phase, can_reshape);
2551 // If the InitializeNode captured me, it made a raw copy of me,
2552 // and I need to disappear.
2553 if (moved != NULL) {
2554 // %%% hack to ensure that Ideal returns a new node:
2555 mem = MergeMemNode::make(mem);
2556 return mem; // fold me away
2557 }
2558 }
2559 }
2560
2561 return NULL; // No further progress
2562 }
2563
2564 //------------------------------Value-----------------------------------------
2565 const Type* StoreNode::Value(PhaseGVN* phase) const {
2566 // Either input is TOP ==> the result is TOP
2567 const Type *t1 = phase->type( in(MemNode::Memory) );
2568 if( t1 == Type::TOP ) return Type::TOP;
2569 const Type *t2 = phase->type( in(MemNode::Address) );
2570 if( t2 == Type::TOP ) return Type::TOP;
2571 const Type *t3 = phase->type( in(MemNode::ValueIn) );
2572 if( t3 == Type::TOP ) return Type::TOP;
2573 return Type::MEMORY;
2574 }
2575
2576 //------------------------------Identity---------------------------------------
2577 // Remove redundant stores:
2578 // Store(m, p, Load(m, p)) changes to m.
2579 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
2580 Node* StoreNode::Identity(PhaseGVN* phase) {
2581 Node* mem = in(MemNode::Memory);
2582 Node* adr = in(MemNode::Address);
2583 Node* val = in(MemNode::ValueIn);
2584
2585 Node* result = this;
2586
2587 // Load then Store? Then the Store is useless
2588 if (val->is_Load() &&
2589 val->in(MemNode::Address)->eqv_uncast(adr) &&
2590 val->in(MemNode::Memory )->eqv_uncast(mem) &&
2591 val->as_Load()->store_Opcode() == Opcode()) {
2592 result = mem;
2593 }
2594
2595 // Two stores in a row of the same value?
2596 if (result == this &&
2597 mem->is_Store() &&
2598 mem->in(MemNode::Address)->eqv_uncast(adr) &&
2599 mem->in(MemNode::ValueIn)->eqv_uncast(val) &&
2600 mem->Opcode() == Opcode()) {
2601 result = mem;
2602 }
2603
2604 // Store of zero anywhere into a freshly-allocated object?
2605 // Then the store is useless.
2606 // (It must already have been captured by the InitializeNode.)
2607 if (result == this &&
2608 ReduceFieldZeroing && phase->type(val)->is_zero_type()) {
2609 // a newly allocated object is already all-zeroes everywhere
2610 if (mem->is_Proj() && mem->in(0)->is_Allocate()) {
2611 result = mem;
2612 }
2613
2614 if (result == this) {
2615 // the store may also apply to zero-bits in an earlier object
2616 Node* prev_mem = find_previous_store(phase);
2617 // Steps (a), (b): Walk past independent stores to find an exact match.
2618 if (prev_mem != NULL) {
2619 Node* prev_val = can_see_stored_value(prev_mem, phase);
2620 if (prev_val != NULL && phase->eqv(prev_val, val)) {
2621 // prev_val and val might differ by a cast; it would be good
2622 // to keep the more informative of the two.
2623 result = mem;
2624 }
2625 }
2626 }
2627 }
2628
2629 if (result != this && phase->is_IterGVN() != NULL) {
2630 MemBarNode* trailing = trailing_membar();
2631 if (trailing != NULL) {
2632 #ifdef ASSERT
2633 const TypeOopPtr* t_oop = phase->type(in(Address))->isa_oopptr();
2634 assert(t_oop == NULL || t_oop->is_known_instance_field(), "only for non escaping objects");
2635 #endif
2636 PhaseIterGVN* igvn = phase->is_IterGVN();
2637 trailing->remove(igvn);
2638 }
2639 }
2640
2641 return result;
2642 }
2643
2644 //------------------------------match_edge-------------------------------------
2645 // Do we Match on this edge index or not? Match only memory & value
2646 uint StoreNode::match_edge(uint idx) const {
2647 return idx == MemNode::Address || idx == MemNode::ValueIn;
2648 }
2649
2650 //------------------------------cmp--------------------------------------------
2651 // Do not common stores up together. They generally have to be split
2652 // back up anyways, so do not bother.
2653 uint StoreNode::cmp( const Node &n ) const {
2654 return (&n == this); // Always fail except on self
2655 }
2656
2657 //------------------------------Ideal_masked_input-----------------------------
2658 // Check for a useless mask before a partial-word store
2659 // (StoreB ... (AndI valIn conIa) )
2660 // If (conIa & mask == mask) this simplifies to
2661 // (StoreB ... (valIn) )
2662 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
2663 Node *val = in(MemNode::ValueIn);
2664 if( val->Opcode() == Op_AndI ) {
2665 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2666 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
2667 set_req(MemNode::ValueIn, val->in(1));
2668 return this;
2669 }
2670 }
2671 return NULL;
2672 }
2673
2674
2675 //------------------------------Ideal_sign_extended_input----------------------
2676 // Check for useless sign-extension before a partial-word store
2677 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) )
2678 // If (conIL == conIR && conIR <= num_bits) this simplifies to
2679 // (StoreB ... (valIn) )
2680 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) {
2681 Node *val = in(MemNode::ValueIn);
2682 if( val->Opcode() == Op_RShiftI ) {
2683 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2684 if( t && t->is_con() && (t->get_con() <= num_bits) ) {
2685 Node *shl = val->in(1);
2686 if( shl->Opcode() == Op_LShiftI ) {
2687 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int();
2688 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) {
2689 set_req(MemNode::ValueIn, shl->in(1));
2690 return this;
2691 }
2692 }
2693 }
2694 }
2695 return NULL;
2696 }
2697
2698 //------------------------------value_never_loaded-----------------------------------
2699 // Determine whether there are any possible loads of the value stored.
2700 // For simplicity, we actually check if there are any loads from the
2701 // address stored to, not just for loads of the value stored by this node.
2702 //
2703 bool StoreNode::value_never_loaded( PhaseTransform *phase) const {
2704 Node *adr = in(Address);
2705 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
2706 if (adr_oop == NULL)
2707 return false;
2708 if (!adr_oop->is_known_instance_field())
2709 return false; // if not a distinct instance, there may be aliases of the address
2710 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
2711 Node *use = adr->fast_out(i);
2712 if (use->is_Load() || use->is_LoadStore()) {
2713 return false;
2714 }
2715 }
2716 return true;
2717 }
2718
2719 MemBarNode* StoreNode::trailing_membar() const {
2720 if (is_release()) {
2721 MemBarNode* trailing_mb = NULL;
2722 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
2723 Node* u = fast_out(i);
2724 if (u->is_MemBar()) {
2725 if (u->as_MemBar()->trailing_store()) {
2726 assert(u->Opcode() == Op_MemBarVolatile, "");
2727 assert(trailing_mb == NULL, "only one");
2728 trailing_mb = u->as_MemBar();
2729 #ifdef ASSERT
2730 Node* leading = u->as_MemBar()->leading_membar();
2731 assert(leading->Opcode() == Op_MemBarRelease, "incorrect membar");
2732 assert(leading->as_MemBar()->leading_store(), "incorrect membar pair");
2733 assert(leading->as_MemBar()->trailing_membar() == u, "incorrect membar pair");
2734 #endif
2735 } else {
2736 assert(u->as_MemBar()->standalone(), "");
2737 }
2738 }
2739 }
2740 return trailing_mb;
2741 }
2742 return NULL;
2743 }
2744
2745
2746 //=============================================================================
2747 //------------------------------Ideal------------------------------------------
2748 // If the store is from an AND mask that leaves the low bits untouched, then
2749 // we can skip the AND operation. If the store is from a sign-extension
2750 // (a left shift, then right shift) we can skip both.
2751 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
2752 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
2753 if( progress != NULL ) return progress;
2754
2755 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
2756 if( progress != NULL ) return progress;
2757
2758 // Finally check the default case
2759 return StoreNode::Ideal(phase, can_reshape);
2760 }
2761
2762 //=============================================================================
2763 //------------------------------Ideal------------------------------------------
2764 // If the store is from an AND mask that leaves the low bits untouched, then
2765 // we can skip the AND operation
2766 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
2767 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
2768 if( progress != NULL ) return progress;
2769
2770 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
2771 if( progress != NULL ) return progress;
2772
2773 // Finally check the default case
2774 return StoreNode::Ideal(phase, can_reshape);
2775 }
2776
2777 //=============================================================================
2778 //------------------------------Identity---------------------------------------
2779 Node* StoreCMNode::Identity(PhaseGVN* phase) {
2780 // No need to card mark when storing a null ptr
2781 Node* my_store = in(MemNode::OopStore);
2782 if (my_store->is_Store()) {
2783 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) );
2784 if( t1 == TypePtr::NULL_PTR ) {
2785 return in(MemNode::Memory);
2786 }
2787 }
2788 return this;
2789 }
2790
2791 //=============================================================================
2792 //------------------------------Ideal---------------------------------------
2793 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){
2794 Node* progress = StoreNode::Ideal(phase, can_reshape);
2795 if (progress != NULL) return progress;
2796
2797 Node* my_store = in(MemNode::OopStore);
2798 if (my_store->is_MergeMem()) {
2799 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx());
2800 set_req(MemNode::OopStore, mem);
2801 return this;
2802 }
2803
2804 return NULL;
2805 }
2806
2807 //------------------------------Value-----------------------------------------
2808 const Type* StoreCMNode::Value(PhaseGVN* phase) const {
2809 // Either input is TOP ==> the result is TOP
2810 const Type *t = phase->type( in(MemNode::Memory) );
2811 if( t == Type::TOP ) return Type::TOP;
2812 t = phase->type( in(MemNode::Address) );
2813 if( t == Type::TOP ) return Type::TOP;
2814 t = phase->type( in(MemNode::ValueIn) );
2815 if( t == Type::TOP ) return Type::TOP;
2816 // If extra input is TOP ==> the result is TOP
2817 t = phase->type( in(MemNode::OopStore) );
2818 if( t == Type::TOP ) return Type::TOP;
2819
2820 return StoreNode::Value( phase );
2821 }
2822
2823
2824 //=============================================================================
2825 //----------------------------------SCMemProjNode------------------------------
2826 const Type* SCMemProjNode::Value(PhaseGVN* phase) const
2827 {
2828 return bottom_type();
2829 }
2830
2831 //=============================================================================
2832 //----------------------------------LoadStoreNode------------------------------
2833 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required )
2834 : Node(required),
2835 _type(rt),
2836 _adr_type(at)
2837 {
2838 init_req(MemNode::Control, c );
2839 init_req(MemNode::Memory , mem);
2840 init_req(MemNode::Address, adr);
2841 init_req(MemNode::ValueIn, val);
2842 init_class_id(Class_LoadStore);
2843 }
2844
2845 uint LoadStoreNode::ideal_reg() const {
2846 return _type->ideal_reg();
2847 }
2848
2849 bool LoadStoreNode::result_not_used() const {
2850 for( DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++ ) {
2851 Node *x = fast_out(i);
2852 if (x->Opcode() == Op_SCMemProj) continue;
2853 return false;
2854 }
2855 return true;
2856 }
2857
2858 MemBarNode* LoadStoreNode::trailing_membar() const {
2859 MemBarNode* trailing = NULL;
2860 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
2861 Node* u = fast_out(i);
2862 if (u->is_MemBar()) {
2863 if (u->as_MemBar()->trailing_load_store()) {
2864 assert(u->Opcode() == Op_MemBarAcquire, "");
2865 assert(trailing == NULL, "only one");
2866 trailing = u->as_MemBar();
2867 #ifdef ASSERT
2868 Node* leading = trailing->leading_membar();
2869 assert(support_IRIW_for_not_multiple_copy_atomic_cpu || leading->Opcode() == Op_MemBarRelease, "incorrect membar");
2870 assert(leading->as_MemBar()->leading_load_store(), "incorrect membar pair");
2871 assert(leading->as_MemBar()->trailing_membar() == trailing, "incorrect membar pair");
2872 #endif
2873 } else {
2874 assert(u->as_MemBar()->standalone(), "wrong barrier kind");
2875 }
2876 }
2877 }
2878
2879 return trailing;
2880 }
2881
2882 uint LoadStoreNode::size_of() const { return sizeof(*this); }
2883
2884 //=============================================================================
2885 //----------------------------------LoadStoreConditionalNode--------------------
2886 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, NULL, TypeInt::BOOL, 5) {
2887 init_req(ExpectedIn, ex );
2888 }
2889
2890 //=============================================================================
2891 //-------------------------------adr_type--------------------------------------
2892 const TypePtr* ClearArrayNode::adr_type() const {
2893 Node *adr = in(3);
2894 if (adr == NULL) return NULL; // node is dead
2895 return MemNode::calculate_adr_type(adr->bottom_type());
2896 }
2897
2898 //------------------------------match_edge-------------------------------------
2899 // Do we Match on this edge index or not? Do not match memory
2900 uint ClearArrayNode::match_edge(uint idx) const {
2901 return idx > 1;
2902 }
2903
2904 //------------------------------Identity---------------------------------------
2905 // Clearing a zero length array does nothing
2906 Node* ClearArrayNode::Identity(PhaseGVN* phase) {
2907 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
2908 }
2909
2910 //------------------------------Idealize---------------------------------------
2911 // Clearing a short array is faster with stores
2912 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2913 // Already know this is a large node, do not try to ideal it
2914 if (!IdealizeClearArrayNode || _is_large) return NULL;
2915
2916 const int unit = BytesPerLong;
2917 const TypeX* t = phase->type(in(2))->isa_intptr_t();
2918 if (!t) return NULL;
2919 if (!t->is_con()) return NULL;
2920 intptr_t raw_count = t->get_con();
2921 intptr_t size = raw_count;
2922 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
2923 // Clearing nothing uses the Identity call.
2924 // Negative clears are possible on dead ClearArrays
2925 // (see jck test stmt114.stmt11402.val).
2926 if (size <= 0 || size % unit != 0) return NULL;
2927 intptr_t count = size / unit;
2928 // Length too long; communicate this to matchers and assemblers.
2929 // Assemblers are responsible to produce fast hardware clears for it.
2930 if (size > InitArrayShortSize) {
2931 return new ClearArrayNode(in(0), in(1), in(2), in(3), true);
2932 }
2933 Node *mem = in(1);
2934 if( phase->type(mem)==Type::TOP ) return NULL;
2935 Node *adr = in(3);
2936 const Type* at = phase->type(adr);
2937 if( at==Type::TOP ) return NULL;
2938 const TypePtr* atp = at->isa_ptr();
2939 // adjust atp to be the correct array element address type
2940 if (atp == NULL) atp = TypePtr::BOTTOM;
2941 else atp = atp->add_offset(Type::OffsetBot);
2942 // Get base for derived pointer purposes
2943 if( adr->Opcode() != Op_AddP ) Unimplemented();
2944 Node *base = adr->in(1);
2945
2946 Node *zero = phase->makecon(TypeLong::ZERO);
2947 Node *off = phase->MakeConX(BytesPerLong);
2948 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
2949 count--;
2950 while( count-- ) {
2951 mem = phase->transform(mem);
2952 adr = phase->transform(new AddPNode(base,adr,off));
2953 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
2954 }
2955 return mem;
2956 }
2957
2958 //----------------------------step_through----------------------------------
2959 // Return allocation input memory edge if it is different instance
2960 // or itself if it is the one we are looking for.
2961 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) {
2962 Node* n = *np;
2963 assert(n->is_ClearArray(), "sanity");
2964 intptr_t offset;
2965 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
2966 // This method is called only before Allocate nodes are expanded
2967 // during macro nodes expansion. Before that ClearArray nodes are
2968 // only generated in PhaseMacroExpand::generate_arraycopy() (before
2969 // Allocate nodes are expanded) which follows allocations.
2970 assert(alloc != NULL, "should have allocation");
2971 if (alloc->_idx == instance_id) {
2972 // Can not bypass initialization of the instance we are looking for.
2973 return false;
2974 }
2975 // Otherwise skip it.
2976 InitializeNode* init = alloc->initialization();
2977 if (init != NULL)
2978 *np = init->in(TypeFunc::Memory);
2979 else
2980 *np = alloc->in(TypeFunc::Memory);
2981 return true;
2982 }
2983
2984 //----------------------------clear_memory-------------------------------------
2985 // Generate code to initialize object storage to zero.
2986 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2987 intptr_t start_offset,
2988 Node* end_offset,
2989 PhaseGVN* phase) {
2990 intptr_t offset = start_offset;
2991
2992 int unit = BytesPerLong;
2993 if ((offset % unit) != 0) {
2994 Node* adr = new AddPNode(dest, dest, phase->MakeConX(offset));
2995 adr = phase->transform(adr);
2996 const TypePtr* atp = TypeRawPtr::BOTTOM;
2997 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
2998 mem = phase->transform(mem);
2999 offset += BytesPerInt;
3000 }
3001 assert((offset % unit) == 0, "");
3002
3003 // Initialize the remaining stuff, if any, with a ClearArray.
3004 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase);
3005 }
3006
3007 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
3008 Node* start_offset,
3009 Node* end_offset,
3010 PhaseGVN* phase) {
3011 if (start_offset == end_offset) {
3012 // nothing to do
3013 return mem;
3014 }
3015
3016 int unit = BytesPerLong;
3017 Node* zbase = start_offset;
3018 Node* zend = end_offset;
3019
3020 // Scale to the unit required by the CPU:
3021 if (!Matcher::init_array_count_is_in_bytes) {
3022 Node* shift = phase->intcon(exact_log2(unit));
3023 zbase = phase->transform(new URShiftXNode(zbase, shift) );
3024 zend = phase->transform(new URShiftXNode(zend, shift) );
3025 }
3026
3027 // Bulk clear double-words
3028 Node* zsize = phase->transform(new SubXNode(zend, zbase) );
3029 Node* adr = phase->transform(new AddPNode(dest, dest, start_offset) );
3030 mem = new ClearArrayNode(ctl, mem, zsize, adr, false);
3031 return phase->transform(mem);
3032 }
3033
3034 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
3035 intptr_t start_offset,
3036 intptr_t end_offset,
3037 PhaseGVN* phase) {
3038 if (start_offset == end_offset) {
3039 // nothing to do
3040 return mem;
3041 }
3042
3043 assert((end_offset % BytesPerInt) == 0, "odd end offset");
3044 intptr_t done_offset = end_offset;
3045 if ((done_offset % BytesPerLong) != 0) {
3046 done_offset -= BytesPerInt;
3047 }
3048 if (done_offset > start_offset) {
3049 mem = clear_memory(ctl, mem, dest,
3050 start_offset, phase->MakeConX(done_offset), phase);
3051 }
3052 if (done_offset < end_offset) { // emit the final 32-bit store
3053 Node* adr = new AddPNode(dest, dest, phase->MakeConX(done_offset));
3054 adr = phase->transform(adr);
3055 const TypePtr* atp = TypeRawPtr::BOTTOM;
3056 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
3057 mem = phase->transform(mem);
3058 done_offset += BytesPerInt;
3059 }
3060 assert(done_offset == end_offset, "");
3061 return mem;
3062 }
3063
3064 //=============================================================================
3065 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
3066 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)),
3067 _adr_type(C->get_adr_type(alias_idx)), _kind(Standalone)
3068 #ifdef ASSERT
3069 , _pair_idx(0)
3070 #endif
3071 {
3072 init_class_id(Class_MemBar);
3073 Node* top = C->top();
3074 init_req(TypeFunc::I_O,top);
3075 init_req(TypeFunc::FramePtr,top);
3076 init_req(TypeFunc::ReturnAdr,top);
3077 if (precedent != NULL)
3078 init_req(TypeFunc::Parms, precedent);
3079 }
3080
3081 //------------------------------cmp--------------------------------------------
3082 uint MemBarNode::hash() const { return NO_HASH; }
3083 uint MemBarNode::cmp( const Node &n ) const {
3084 return (&n == this); // Always fail except on self
3085 }
3086
3087 //------------------------------make-------------------------------------------
3088 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
3089 switch (opcode) {
3090 case Op_MemBarAcquire: return new MemBarAcquireNode(C, atp, pn);
3091 case Op_LoadFence: return new LoadFenceNode(C, atp, pn);
3092 case Op_MemBarRelease: return new MemBarReleaseNode(C, atp, pn);
3093 case Op_StoreFence: return new StoreFenceNode(C, atp, pn);
3094 case Op_MemBarAcquireLock: return new MemBarAcquireLockNode(C, atp, pn);
3095 case Op_MemBarReleaseLock: return new MemBarReleaseLockNode(C, atp, pn);
3096 case Op_MemBarVolatile: return new MemBarVolatileNode(C, atp, pn);
3097 case Op_MemBarCPUOrder: return new MemBarCPUOrderNode(C, atp, pn);
3098 case Op_OnSpinWait: return new OnSpinWaitNode(C, atp, pn);
3099 case Op_Initialize: return new InitializeNode(C, atp, pn);
3100 case Op_MemBarStoreStore: return new MemBarStoreStoreNode(C, atp, pn);
3101 default: ShouldNotReachHere(); return NULL;
3102 }
3103 }
3104
3105 void MemBarNode::remove(PhaseIterGVN *igvn) {
3106 if (outcnt() != 2) {
3107 return;
3108 }
3109 if (trailing_store() || trailing_load_store()) {
3110 MemBarNode* leading = leading_membar();
3111 if (leading != NULL) {
3112 assert(leading->trailing_membar() == this, "inconsistent leading/trailing membars");
3113 leading->remove(igvn);
3114 }
3115 }
3116 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
3117 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
3118 }
3119
3120 //------------------------------Ideal------------------------------------------
3121 // Return a node which is more "ideal" than the current node. Strip out
3122 // control copies
3123 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3124 if (remove_dead_region(phase, can_reshape)) return this;
3125 // Don't bother trying to transform a dead node
3126 if (in(0) && in(0)->is_top()) {
3127 return NULL;
3128 }
3129
3130 #if INCLUDE_ZGC
3131 if (UseZGC) {
3132 if (req() == (Precedent+1) && in(MemBarNode::Precedent)->in(0) != NULL && in(MemBarNode::Precedent)->in(0)->is_LoadBarrier()) {
3133 Node* load_node = in(MemBarNode::Precedent)->in(0)->in(LoadBarrierNode::Oop);
3134 set_req(MemBarNode::Precedent, load_node);
3135 return this;
3136 }
3137 }
3138 #endif
3139
3140 bool progress = false;
3141 // Eliminate volatile MemBars for scalar replaced objects.
3142 if (can_reshape && req() == (Precedent+1)) {
3143 bool eliminate = false;
3144 int opc = Opcode();
3145 if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) {
3146 // Volatile field loads and stores.
3147 Node* my_mem = in(MemBarNode::Precedent);
3148 // The MembarAquire may keep an unused LoadNode alive through the Precedent edge
3149 if ((my_mem != NULL) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) {
3150 // if the Precedent is a decodeN and its input (a Load) is used at more than one place,
3151 // replace this Precedent (decodeN) with the Load instead.
3152 if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1)) {
3153 Node* load_node = my_mem->in(1);
3154 set_req(MemBarNode::Precedent, load_node);
3155 phase->is_IterGVN()->_worklist.push(my_mem);
3156 my_mem = load_node;
3157 } else {
3158 assert(my_mem->unique_out() == this, "sanity");
3159 del_req(Precedent);
3160 phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later
3161 my_mem = NULL;
3162 }
3163 progress = true;
3164 }
3165 if (my_mem != NULL && my_mem->is_Mem()) {
3166 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
3167 // Check for scalar replaced object reference.
3168 if( t_oop != NULL && t_oop->is_known_instance_field() &&
3169 t_oop->offset() != Type::OffsetBot &&
3170 t_oop->offset() != Type::OffsetTop) {
3171 eliminate = true;
3172 }
3173 }
3174 } else if (opc == Op_MemBarRelease) {
3175 // Final field stores.
3176 Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent), phase);
3177 if ((alloc != NULL) && alloc->is_Allocate() &&
3178 alloc->as_Allocate()->does_not_escape_thread()) {
3179 // The allocated object does not escape.
3180 eliminate = true;
3181 }
3182 }
3183 if (eliminate) {
3184 // Replace MemBar projections by its inputs.
3185 PhaseIterGVN* igvn = phase->is_IterGVN();
3186 remove(igvn);
3187 // Must return either the original node (now dead) or a new node
3188 // (Do not return a top here, since that would break the uniqueness of top.)
3189 return new ConINode(TypeInt::ZERO);
3190 }
3191 }
3192 return progress ? this : NULL;
3193 }
3194
3195 //------------------------------Value------------------------------------------
3196 const Type* MemBarNode::Value(PhaseGVN* phase) const {
3197 if( !in(0) ) return Type::TOP;
3198 if( phase->type(in(0)) == Type::TOP )
3199 return Type::TOP;
3200 return TypeTuple::MEMBAR;
3201 }
3202
3203 //------------------------------match------------------------------------------
3204 // Construct projections for memory.
3205 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) {
3206 switch (proj->_con) {
3207 case TypeFunc::Control:
3208 case TypeFunc::Memory:
3209 return new MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
3210 }
3211 ShouldNotReachHere();
3212 return NULL;
3213 }
3214
3215 void MemBarNode::set_store_pair(MemBarNode* leading, MemBarNode* trailing) {
3216 trailing->_kind = TrailingStore;
3217 leading->_kind = LeadingStore;
3218 #ifdef ASSERT
3219 trailing->_pair_idx = leading->_idx;
3220 leading->_pair_idx = leading->_idx;
3221 #endif
3222 }
3223
3224 void MemBarNode::set_load_store_pair(MemBarNode* leading, MemBarNode* trailing) {
3225 trailing->_kind = TrailingLoadStore;
3226 leading->_kind = LeadingLoadStore;
3227 #ifdef ASSERT
3228 trailing->_pair_idx = leading->_idx;
3229 leading->_pair_idx = leading->_idx;
3230 #endif
3231 }
3232
3233 MemBarNode* MemBarNode::trailing_membar() const {
3234 ResourceMark rm;
3235 Node* trailing = (Node*)this;
3236 VectorSet seen(Thread::current()->resource_area());
3237 Node_Stack multis(0);
3238 do {
3239 Node* c = trailing;
3240 uint i = 0;
3241 do {
3242 trailing = NULL;
3243 for (; i < c->outcnt(); i++) {
3244 Node* next = c->raw_out(i);
3245 if (next != c && next->is_CFG()) {
3246 if (c->is_MultiBranch()) {
3247 if (multis.node() == c) {
3248 multis.set_index(i+1);
3249 } else {
3250 multis.push(c, i+1);
3251 }
3252 }
3253 trailing = next;
3254 break;
3255 }
3256 }
3257 if (trailing != NULL && !seen.test_set(trailing->_idx)) {
3258 break;
3259 }
3260 while (multis.size() > 0) {
3261 c = multis.node();
3262 i = multis.index();
3263 if (i < c->req()) {
3264 break;
3265 }
3266 multis.pop();
3267 }
3268 } while (multis.size() > 0);
3269 } while (!trailing->is_MemBar() || !trailing->as_MemBar()->trailing());
3270
3271 MemBarNode* mb = trailing->as_MemBar();
3272 assert((mb->_kind == TrailingStore && _kind == LeadingStore) ||
3273 (mb->_kind == TrailingLoadStore && _kind == LeadingLoadStore), "bad trailing membar");
3274 assert(mb->_pair_idx == _pair_idx, "bad trailing membar");
3275 return mb;
3276 }
3277
3278 MemBarNode* MemBarNode::leading_membar() const {
3279 ResourceMark rm;
3280 VectorSet seen(Thread::current()->resource_area());
3281 Node_Stack regions(0);
3282 Node* leading = in(0);
3283 while (leading != NULL && (!leading->is_MemBar() || !leading->as_MemBar()->leading())) {
3284 while (leading == NULL || leading->is_top() || seen.test_set(leading->_idx)) {
3285 leading = NULL;
3286 while (regions.size() > 0 && leading == NULL) {
3287 Node* r = regions.node();
3288 uint i = regions.index();
3289 if (i < r->req()) {
3290 leading = r->in(i);
3291 regions.set_index(i+1);
3292 } else {
3293 regions.pop();
3294 }
3295 }
3296 if (leading == NULL) {
3297 assert(regions.size() == 0, "all paths should have been tried");
3298 return NULL;
3299 }
3300 }
3301 if (leading->is_Region()) {
3302 regions.push(leading, 2);
3303 leading = leading->in(1);
3304 } else {
3305 leading = leading->in(0);
3306 }
3307 }
3308 #ifdef ASSERT
3309 Unique_Node_List wq;
3310 wq.push((Node*)this);
3311 uint found = 0;
3312 for (uint i = 0; i < wq.size(); i++) {
3313 Node* n = wq.at(i);
3314 if (n->is_Region()) {
3315 for (uint j = 1; j < n->req(); j++) {
3316 Node* in = n->in(j);
3317 if (in != NULL && !in->is_top()) {
3318 wq.push(in);
3319 }
3320 }
3321 } else {
3322 if (n->is_MemBar() && n->as_MemBar()->leading()) {
3323 assert(n == leading, "consistency check failed");
3324 found++;
3325 } else {
3326 Node* in = n->in(0);
3327 if (in != NULL && !in->is_top()) {
3328 wq.push(in);
3329 }
3330 }
3331 }
3332 }
3333 assert(found == 1 || (found == 0 && leading == NULL), "consistency check failed");
3334 #endif
3335 if (leading == NULL) {
3336 return NULL;
3337 }
3338 MemBarNode* mb = leading->as_MemBar();
3339 assert((mb->_kind == LeadingStore && _kind == TrailingStore) ||
3340 (mb->_kind == LeadingLoadStore && _kind == TrailingLoadStore), "bad leading membar");
3341 assert(mb->_pair_idx == _pair_idx, "bad leading membar");
3342 return mb;
3343 }
3344
3345 //===========================InitializeNode====================================
3346 // SUMMARY:
3347 // This node acts as a memory barrier on raw memory, after some raw stores.
3348 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
3349 // The Initialize can 'capture' suitably constrained stores as raw inits.
3350 // It can coalesce related raw stores into larger units (called 'tiles').
3351 // It can avoid zeroing new storage for memory units which have raw inits.
3352 // At macro-expansion, it is marked 'complete', and does not optimize further.
3353 //
3354 // EXAMPLE:
3355 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
3356 // ctl = incoming control; mem* = incoming memory
3357 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
3358 // First allocate uninitialized memory and fill in the header:
3359 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
3360 // ctl := alloc.Control; mem* := alloc.Memory*
3361 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
3362 // Then initialize to zero the non-header parts of the raw memory block:
3363 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
3364 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
3365 // After the initialize node executes, the object is ready for service:
3366 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
3367 // Suppose its body is immediately initialized as {1,2}:
3368 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3369 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3370 // mem.SLICE(#short[*]) := store2
3371 //
3372 // DETAILS:
3373 // An InitializeNode collects and isolates object initialization after
3374 // an AllocateNode and before the next possible safepoint. As a
3375 // memory barrier (MemBarNode), it keeps critical stores from drifting
3376 // down past any safepoint or any publication of the allocation.
3377 // Before this barrier, a newly-allocated object may have uninitialized bits.
3378 // After this barrier, it may be treated as a real oop, and GC is allowed.
3379 //
3380 // The semantics of the InitializeNode include an implicit zeroing of
3381 // the new object from object header to the end of the object.
3382 // (The object header and end are determined by the AllocateNode.)
3383 //
3384 // Certain stores may be added as direct inputs to the InitializeNode.
3385 // These stores must update raw memory, and they must be to addresses
3386 // derived from the raw address produced by AllocateNode, and with
3387 // a constant offset. They must be ordered by increasing offset.
3388 // The first one is at in(RawStores), the last at in(req()-1).
3389 // Unlike most memory operations, they are not linked in a chain,
3390 // but are displayed in parallel as users of the rawmem output of
3391 // the allocation.
3392 //
3393 // (See comments in InitializeNode::capture_store, which continue
3394 // the example given above.)
3395 //
3396 // When the associated Allocate is macro-expanded, the InitializeNode
3397 // may be rewritten to optimize collected stores. A ClearArrayNode
3398 // may also be created at that point to represent any required zeroing.
3399 // The InitializeNode is then marked 'complete', prohibiting further
3400 // capturing of nearby memory operations.
3401 //
3402 // During macro-expansion, all captured initializations which store
3403 // constant values of 32 bits or smaller are coalesced (if advantageous)
3404 // into larger 'tiles' 32 or 64 bits. This allows an object to be
3405 // initialized in fewer memory operations. Memory words which are
3406 // covered by neither tiles nor non-constant stores are pre-zeroed
3407 // by explicit stores of zero. (The code shape happens to do all
3408 // zeroing first, then all other stores, with both sequences occurring
3409 // in order of ascending offsets.)
3410 //
3411 // Alternatively, code may be inserted between an AllocateNode and its
3412 // InitializeNode, to perform arbitrary initialization of the new object.
3413 // E.g., the object copying intrinsics insert complex data transfers here.
3414 // The initialization must then be marked as 'complete' disable the
3415 // built-in zeroing semantics and the collection of initializing stores.
3416 //
3417 // While an InitializeNode is incomplete, reads from the memory state
3418 // produced by it are optimizable if they match the control edge and
3419 // new oop address associated with the allocation/initialization.
3420 // They return a stored value (if the offset matches) or else zero.
3421 // A write to the memory state, if it matches control and address,
3422 // and if it is to a constant offset, may be 'captured' by the
3423 // InitializeNode. It is cloned as a raw memory operation and rewired
3424 // inside the initialization, to the raw oop produced by the allocation.
3425 // Operations on addresses which are provably distinct (e.g., to
3426 // other AllocateNodes) are allowed to bypass the initialization.
3427 //
3428 // The effect of all this is to consolidate object initialization
3429 // (both arrays and non-arrays, both piecewise and bulk) into a
3430 // single location, where it can be optimized as a unit.
3431 //
3432 // Only stores with an offset less than TrackedInitializationLimit words
3433 // will be considered for capture by an InitializeNode. This puts a
3434 // reasonable limit on the complexity of optimized initializations.
3435
3436 //---------------------------InitializeNode------------------------------------
3437 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
3438 : _is_complete(Incomplete), _does_not_escape(false),
3439 MemBarNode(C, adr_type, rawoop)
3440 {
3441 init_class_id(Class_Initialize);
3442
3443 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
3444 assert(in(RawAddress) == rawoop, "proper init");
3445 // Note: allocation() can be NULL, for secondary initialization barriers
3446 }
3447
3448 // Since this node is not matched, it will be processed by the
3449 // register allocator. Declare that there are no constraints
3450 // on the allocation of the RawAddress edge.
3451 const RegMask &InitializeNode::in_RegMask(uint idx) const {
3452 // This edge should be set to top, by the set_complete. But be conservative.
3453 if (idx == InitializeNode::RawAddress)
3454 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
3455 return RegMask::Empty;
3456 }
3457
3458 Node* InitializeNode::memory(uint alias_idx) {
3459 Node* mem = in(Memory);
3460 if (mem->is_MergeMem()) {
3461 return mem->as_MergeMem()->memory_at(alias_idx);
3462 } else {
3463 // incoming raw memory is not split
3464 return mem;
3465 }
3466 }
3467
3468 bool InitializeNode::is_non_zero() {
3469 if (is_complete()) return false;
3470 remove_extra_zeroes();
3471 return (req() > RawStores);
3472 }
3473
3474 void InitializeNode::set_complete(PhaseGVN* phase) {
3475 assert(!is_complete(), "caller responsibility");
3476 _is_complete = Complete;
3477
3478 // After this node is complete, it contains a bunch of
3479 // raw-memory initializations. There is no need for
3480 // it to have anything to do with non-raw memory effects.
3481 // Therefore, tell all non-raw users to re-optimize themselves,
3482 // after skipping the memory effects of this initialization.
3483 PhaseIterGVN* igvn = phase->is_IterGVN();
3484 if (igvn) igvn->add_users_to_worklist(this);
3485 }
3486
3487 // convenience function
3488 // return false if the init contains any stores already
3489 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
3490 InitializeNode* init = initialization();
3491 if (init == NULL || init->is_complete()) return false;
3492 init->remove_extra_zeroes();
3493 // for now, if this allocation has already collected any inits, bail:
3494 if (init->is_non_zero()) return false;
3495 init->set_complete(phase);
3496 return true;
3497 }
3498
3499 void InitializeNode::remove_extra_zeroes() {
3500 if (req() == RawStores) return;
3501 Node* zmem = zero_memory();
3502 uint fill = RawStores;
3503 for (uint i = fill; i < req(); i++) {
3504 Node* n = in(i);
3505 if (n->is_top() || n == zmem) continue; // skip
3506 if (fill < i) set_req(fill, n); // compact
3507 ++fill;
3508 }
3509 // delete any empty spaces created:
3510 while (fill < req()) {
3511 del_req(fill);
3512 }
3513 }
3514
3515 // Helper for remembering which stores go with which offsets.
3516 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) {
3517 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
3518 intptr_t offset = -1;
3519 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
3520 phase, offset);
3521 if (base == NULL) return -1; // something is dead,
3522 if (offset < 0) return -1; // dead, dead
3523 return offset;
3524 }
3525
3526 // Helper for proving that an initialization expression is
3527 // "simple enough" to be folded into an object initialization.
3528 // Attempts to prove that a store's initial value 'n' can be captured
3529 // within the initialization without creating a vicious cycle, such as:
3530 // { Foo p = new Foo(); p.next = p; }
3531 // True for constants and parameters and small combinations thereof.
3532 bool InitializeNode::detect_init_independence(Node* n, int& count) {
3533 if (n == NULL) return true; // (can this really happen?)
3534 if (n->is_Proj()) n = n->in(0);
3535 if (n == this) return false; // found a cycle
3536 if (n->is_Con()) return true;
3537 if (n->is_Start()) return true; // params, etc., are OK
3538 if (n->is_Root()) return true; // even better
3539
3540 Node* ctl = n->in(0);
3541 if (ctl != NULL && !ctl->is_top()) {
3542 if (ctl->is_Proj()) ctl = ctl->in(0);
3543 if (ctl == this) return false;
3544
3545 // If we already know that the enclosing memory op is pinned right after
3546 // the init, then any control flow that the store has picked up
3547 // must have preceded the init, or else be equal to the init.
3548 // Even after loop optimizations (which might change control edges)
3549 // a store is never pinned *before* the availability of its inputs.
3550 if (!MemNode::all_controls_dominate(n, this))
3551 return false; // failed to prove a good control
3552 }
3553
3554 // Check data edges for possible dependencies on 'this'.
3555 if ((count += 1) > 20) return false; // complexity limit
3556 for (uint i = 1; i < n->req(); i++) {
3557 Node* m = n->in(i);
3558 if (m == NULL || m == n || m->is_top()) continue;
3559 uint first_i = n->find_edge(m);
3560 if (i != first_i) continue; // process duplicate edge just once
3561 if (!detect_init_independence(m, count)) {
3562 return false;
3563 }
3564 }
3565
3566 return true;
3567 }
3568
3569 // Here are all the checks a Store must pass before it can be moved into
3570 // an initialization. Returns zero if a check fails.
3571 // On success, returns the (constant) offset to which the store applies,
3572 // within the initialized memory.
3573 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase, bool can_reshape) {
3574 const int FAIL = 0;
3575 if (st->req() != MemNode::ValueIn + 1)
3576 return FAIL; // an inscrutable StoreNode (card mark?)
3577 Node* ctl = st->in(MemNode::Control);
3578 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this))
3579 return FAIL; // must be unconditional after the initialization
3580 Node* mem = st->in(MemNode::Memory);
3581 if (!(mem->is_Proj() && mem->in(0) == this))
3582 return FAIL; // must not be preceded by other stores
3583 Node* adr = st->in(MemNode::Address);
3584 intptr_t offset;
3585 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
3586 if (alloc == NULL)
3587 return FAIL; // inscrutable address
3588 if (alloc != allocation())
3589 return FAIL; // wrong allocation! (store needs to float up)
3590 int size_in_bytes = st->memory_size();
3591 if ((size_in_bytes != 0) && (offset % size_in_bytes) != 0) {
3592 return FAIL; // mismatched access
3593 }
3594 Node* val = st->in(MemNode::ValueIn);
3595 int complexity_count = 0;
3596 if (!detect_init_independence(val, complexity_count))
3597 return FAIL; // stored value must be 'simple enough'
3598
3599 // The Store can be captured only if nothing after the allocation
3600 // and before the Store is using the memory location that the store
3601 // overwrites.
3602 bool failed = false;
3603 // If is_complete_with_arraycopy() is true the shape of the graph is
3604 // well defined and is safe so no need for extra checks.
3605 if (!is_complete_with_arraycopy()) {
3606 // We are going to look at each use of the memory state following
3607 // the allocation to make sure nothing reads the memory that the
3608 // Store writes.
3609 const TypePtr* t_adr = phase->type(adr)->isa_ptr();
3610 int alias_idx = phase->C->get_alias_index(t_adr);
3611 ResourceMark rm;
3612 Unique_Node_List mems;
3613 mems.push(mem);
3614 Node* unique_merge = NULL;
3615 for (uint next = 0; next < mems.size(); ++next) {
3616 Node *m = mems.at(next);
3617 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
3618 Node *n = m->fast_out(j);
3619 if (n->outcnt() == 0) {
3620 continue;
3621 }
3622 if (n == st) {
3623 continue;
3624 } else if (n->in(0) != NULL && n->in(0) != ctl) {
3625 // If the control of this use is different from the control
3626 // of the Store which is right after the InitializeNode then
3627 // this node cannot be between the InitializeNode and the
3628 // Store.
3629 continue;
3630 } else if (n->is_MergeMem()) {
3631 if (n->as_MergeMem()->memory_at(alias_idx) == m) {
3632 // We can hit a MergeMemNode (that will likely go away
3633 // later) that is a direct use of the memory state
3634 // following the InitializeNode on the same slice as the
3635 // store node that we'd like to capture. We need to check
3636 // the uses of the MergeMemNode.
3637 mems.push(n);
3638 }
3639 } else if (n->is_Mem()) {
3640 Node* other_adr = n->in(MemNode::Address);
3641 if (other_adr == adr) {
3642 failed = true;
3643 break;
3644 } else {
3645 const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr();
3646 if (other_t_adr != NULL) {
3647 int other_alias_idx = phase->C->get_alias_index(other_t_adr);
3648 if (other_alias_idx == alias_idx) {
3649 // A load from the same memory slice as the store right
3650 // after the InitializeNode. We check the control of the
3651 // object/array that is loaded from. If it's the same as
3652 // the store control then we cannot capture the store.
3653 assert(!n->is_Store(), "2 stores to same slice on same control?");
3654 Node* base = other_adr;
3655 assert(base->is_AddP(), "should be addp but is %s", base->Name());
3656 base = base->in(AddPNode::Base);
3657 if (base != NULL) {
3658 base = base->uncast();
3659 if (base->is_Proj() && base->in(0) == alloc) {
3660 failed = true;
3661 break;
3662 }
3663 }
3664 }
3665 }
3666 }
3667 } else {
3668 failed = true;
3669 break;
3670 }
3671 }
3672 }
3673 }
3674 if (failed) {
3675 if (!can_reshape) {
3676 // We decided we couldn't capture the store during parsing. We
3677 // should try again during the next IGVN once the graph is
3678 // cleaner.
3679 phase->C->record_for_igvn(st);
3680 }
3681 return FAIL;
3682 }
3683
3684 return offset; // success
3685 }
3686
3687 // Find the captured store in(i) which corresponds to the range
3688 // [start..start+size) in the initialized object.
3689 // If there is one, return its index i. If there isn't, return the
3690 // negative of the index where it should be inserted.
3691 // Return 0 if the queried range overlaps an initialization boundary
3692 // or if dead code is encountered.
3693 // If size_in_bytes is zero, do not bother with overlap checks.
3694 int InitializeNode::captured_store_insertion_point(intptr_t start,
3695 int size_in_bytes,
3696 PhaseTransform* phase) {
3697 const int FAIL = 0, MAX_STORE = BytesPerLong;
3698
3699 if (is_complete())
3700 return FAIL; // arraycopy got here first; punt
3701
3702 assert(allocation() != NULL, "must be present");
3703
3704 // no negatives, no header fields:
3705 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
3706
3707 // after a certain size, we bail out on tracking all the stores:
3708 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3709 if (start >= ti_limit) return FAIL;
3710
3711 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
3712 if (i >= limit) return -(int)i; // not found; here is where to put it
3713
3714 Node* st = in(i);
3715 intptr_t st_off = get_store_offset(st, phase);
3716 if (st_off < 0) {
3717 if (st != zero_memory()) {
3718 return FAIL; // bail out if there is dead garbage
3719 }
3720 } else if (st_off > start) {
3721 // ...we are done, since stores are ordered
3722 if (st_off < start + size_in_bytes) {
3723 return FAIL; // the next store overlaps
3724 }
3725 return -(int)i; // not found; here is where to put it
3726 } else if (st_off < start) {
3727 if (size_in_bytes != 0 &&
3728 start < st_off + MAX_STORE &&
3729 start < st_off + st->as_Store()->memory_size()) {
3730 return FAIL; // the previous store overlaps
3731 }
3732 } else {
3733 if (size_in_bytes != 0 &&
3734 st->as_Store()->memory_size() != size_in_bytes) {
3735 return FAIL; // mismatched store size
3736 }
3737 return i;
3738 }
3739
3740 ++i;
3741 }
3742 }
3743
3744 // Look for a captured store which initializes at the offset 'start'
3745 // with the given size. If there is no such store, and no other
3746 // initialization interferes, then return zero_memory (the memory
3747 // projection of the AllocateNode).
3748 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
3749 PhaseTransform* phase) {
3750 assert(stores_are_sane(phase), "");
3751 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3752 if (i == 0) {
3753 return NULL; // something is dead
3754 } else if (i < 0) {
3755 return zero_memory(); // just primordial zero bits here
3756 } else {
3757 Node* st = in(i); // here is the store at this position
3758 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
3759 return st;
3760 }
3761 }
3762
3763 // Create, as a raw pointer, an address within my new object at 'offset'.
3764 Node* InitializeNode::make_raw_address(intptr_t offset,
3765 PhaseTransform* phase) {
3766 Node* addr = in(RawAddress);
3767 if (offset != 0) {
3768 Compile* C = phase->C;
3769 addr = phase->transform( new AddPNode(C->top(), addr,
3770 phase->MakeConX(offset)) );
3771 }
3772 return addr;
3773 }
3774
3775 // Clone the given store, converting it into a raw store
3776 // initializing a field or element of my new object.
3777 // Caller is responsible for retiring the original store,
3778 // with subsume_node or the like.
3779 //
3780 // From the example above InitializeNode::InitializeNode,
3781 // here are the old stores to be captured:
3782 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3783 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3784 //
3785 // Here is the changed code; note the extra edges on init:
3786 // alloc = (Allocate ...)
3787 // rawoop = alloc.RawAddress
3788 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
3789 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
3790 // init = (Initialize alloc.Control alloc.Memory rawoop
3791 // rawstore1 rawstore2)
3792 //
3793 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
3794 PhaseTransform* phase, bool can_reshape) {
3795 assert(stores_are_sane(phase), "");
3796
3797 if (start < 0) return NULL;
3798 assert(can_capture_store(st, phase, can_reshape) == start, "sanity");
3799
3800 Compile* C = phase->C;
3801 int size_in_bytes = st->memory_size();
3802 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3803 if (i == 0) return NULL; // bail out
3804 Node* prev_mem = NULL; // raw memory for the captured store
3805 if (i > 0) {
3806 prev_mem = in(i); // there is a pre-existing store under this one
3807 set_req(i, C->top()); // temporarily disconnect it
3808 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
3809 } else {
3810 i = -i; // no pre-existing store
3811 prev_mem = zero_memory(); // a slice of the newly allocated object
3812 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
3813 set_req(--i, C->top()); // reuse this edge; it has been folded away
3814 else
3815 ins_req(i, C->top()); // build a new edge
3816 }
3817 Node* new_st = st->clone();
3818 new_st->set_req(MemNode::Control, in(Control));
3819 new_st->set_req(MemNode::Memory, prev_mem);
3820 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
3821 new_st = phase->transform(new_st);
3822
3823 // At this point, new_st might have swallowed a pre-existing store
3824 // at the same offset, or perhaps new_st might have disappeared,
3825 // if it redundantly stored the same value (or zero to fresh memory).
3826
3827 // In any case, wire it in:
3828 phase->igvn_rehash_node_delayed(this);
3829 set_req(i, new_st);
3830
3831 // The caller may now kill the old guy.
3832 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
3833 assert(check_st == new_st || check_st == NULL, "must be findable");
3834 assert(!is_complete(), "");
3835 return new_st;
3836 }
3837
3838 static bool store_constant(jlong* tiles, int num_tiles,
3839 intptr_t st_off, int st_size,
3840 jlong con) {
3841 if ((st_off & (st_size-1)) != 0)
3842 return false; // strange store offset (assume size==2**N)
3843 address addr = (address)tiles + st_off;
3844 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
3845 switch (st_size) {
3846 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
3847 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
3848 case sizeof(jint): *(jint*) addr = (jint) con; break;
3849 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
3850 default: return false; // strange store size (detect size!=2**N here)
3851 }
3852 return true; // return success to caller
3853 }
3854
3855 // Coalesce subword constants into int constants and possibly
3856 // into long constants. The goal, if the CPU permits,
3857 // is to initialize the object with a small number of 64-bit tiles.
3858 // Also, convert floating-point constants to bit patterns.
3859 // Non-constants are not relevant to this pass.
3860 //
3861 // In terms of the running example on InitializeNode::InitializeNode
3862 // and InitializeNode::capture_store, here is the transformation
3863 // of rawstore1 and rawstore2 into rawstore12:
3864 // alloc = (Allocate ...)
3865 // rawoop = alloc.RawAddress
3866 // tile12 = 0x00010002
3867 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
3868 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
3869 //
3870 void
3871 InitializeNode::coalesce_subword_stores(intptr_t header_size,
3872 Node* size_in_bytes,
3873 PhaseGVN* phase) {
3874 Compile* C = phase->C;
3875
3876 assert(stores_are_sane(phase), "");
3877 // Note: After this pass, they are not completely sane,
3878 // since there may be some overlaps.
3879
3880 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
3881
3882 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3883 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
3884 size_limit = MIN2(size_limit, ti_limit);
3885 size_limit = align_up(size_limit, BytesPerLong);
3886 int num_tiles = size_limit / BytesPerLong;
3887
3888 // allocate space for the tile map:
3889 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
3890 jlong tiles_buf[small_len];
3891 Node* nodes_buf[small_len];
3892 jlong inits_buf[small_len];
3893 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
3894 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3895 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
3896 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
3897 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
3898 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3899 // tiles: exact bitwise model of all primitive constants
3900 // nodes: last constant-storing node subsumed into the tiles model
3901 // inits: which bytes (in each tile) are touched by any initializations
3902
3903 //// Pass A: Fill in the tile model with any relevant stores.
3904
3905 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
3906 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
3907 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
3908 Node* zmem = zero_memory(); // initially zero memory state
3909 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3910 Node* st = in(i);
3911 intptr_t st_off = get_store_offset(st, phase);
3912
3913 // Figure out the store's offset and constant value:
3914 if (st_off < header_size) continue; //skip (ignore header)
3915 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
3916 int st_size = st->as_Store()->memory_size();
3917 if (st_off + st_size > size_limit) break;
3918
3919 // Record which bytes are touched, whether by constant or not.
3920 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
3921 continue; // skip (strange store size)
3922
3923 const Type* val = phase->type(st->in(MemNode::ValueIn));
3924 if (!val->singleton()) continue; //skip (non-con store)
3925 BasicType type = val->basic_type();
3926
3927 jlong con = 0;
3928 switch (type) {
3929 case T_INT: con = val->is_int()->get_con(); break;
3930 case T_LONG: con = val->is_long()->get_con(); break;
3931 case T_FLOAT: con = jint_cast(val->getf()); break;
3932 case T_DOUBLE: con = jlong_cast(val->getd()); break;
3933 default: continue; //skip (odd store type)
3934 }
3935
3936 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
3937 st->Opcode() == Op_StoreL) {
3938 continue; // This StoreL is already optimal.
3939 }
3940
3941 // Store down the constant.
3942 store_constant(tiles, num_tiles, st_off, st_size, con);
3943
3944 intptr_t j = st_off >> LogBytesPerLong;
3945
3946 if (type == T_INT && st_size == BytesPerInt
3947 && (st_off & BytesPerInt) == BytesPerInt) {
3948 jlong lcon = tiles[j];
3949 if (!Matcher::isSimpleConstant64(lcon) &&
3950 st->Opcode() == Op_StoreI) {
3951 // This StoreI is already optimal by itself.
3952 jint* intcon = (jint*) &tiles[j];
3953 intcon[1] = 0; // undo the store_constant()
3954
3955 // If the previous store is also optimal by itself, back up and
3956 // undo the action of the previous loop iteration... if we can.
3957 // But if we can't, just let the previous half take care of itself.
3958 st = nodes[j];
3959 st_off -= BytesPerInt;
3960 con = intcon[0];
3961 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) {
3962 assert(st_off >= header_size, "still ignoring header");
3963 assert(get_store_offset(st, phase) == st_off, "must be");
3964 assert(in(i-1) == zmem, "must be");
3965 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
3966 assert(con == tcon->is_int()->get_con(), "must be");
3967 // Undo the effects of the previous loop trip, which swallowed st:
3968 intcon[0] = 0; // undo store_constant()
3969 set_req(i-1, st); // undo set_req(i, zmem)
3970 nodes[j] = NULL; // undo nodes[j] = st
3971 --old_subword; // undo ++old_subword
3972 }
3973 continue; // This StoreI is already optimal.
3974 }
3975 }
3976
3977 // This store is not needed.
3978 set_req(i, zmem);
3979 nodes[j] = st; // record for the moment
3980 if (st_size < BytesPerLong) // something has changed
3981 ++old_subword; // includes int/float, but who's counting...
3982 else ++old_long;
3983 }
3984
3985 if ((old_subword + old_long) == 0)
3986 return; // nothing more to do
3987
3988 //// Pass B: Convert any non-zero tiles into optimal constant stores.
3989 // Be sure to insert them before overlapping non-constant stores.
3990 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
3991 for (int j = 0; j < num_tiles; j++) {
3992 jlong con = tiles[j];
3993 jlong init = inits[j];
3994 if (con == 0) continue;
3995 jint con0, con1; // split the constant, address-wise
3996 jint init0, init1; // split the init map, address-wise
3997 { union { jlong con; jint intcon[2]; } u;
3998 u.con = con;
3999 con0 = u.intcon[0];
4000 con1 = u.intcon[1];
4001 u.con = init;
4002 init0 = u.intcon[0];
4003 init1 = u.intcon[1];
4004 }
4005
4006 Node* old = nodes[j];
4007 assert(old != NULL, "need the prior store");
4008 intptr_t offset = (j * BytesPerLong);
4009
4010 bool split = !Matcher::isSimpleConstant64(con);
4011
4012 if (offset < header_size) {
4013 assert(offset + BytesPerInt >= header_size, "second int counts");
4014 assert(*(jint*)&tiles[j] == 0, "junk in header");
4015 split = true; // only the second word counts
4016 // Example: int a[] = { 42 ... }
4017 } else if (con0 == 0 && init0 == -1) {
4018 split = true; // first word is covered by full inits
4019 // Example: int a[] = { ... foo(), 42 ... }
4020 } else if (con1 == 0 && init1 == -1) {
4021 split = true; // second word is covered by full inits
4022 // Example: int a[] = { ... 42, foo() ... }
4023 }
4024
4025 // Here's a case where init0 is neither 0 nor -1:
4026 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
4027 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
4028 // In this case the tile is not split; it is (jlong)42.
4029 // The big tile is stored down, and then the foo() value is inserted.
4030 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
4031
4032 Node* ctl = old->in(MemNode::Control);
4033 Node* adr = make_raw_address(offset, phase);
4034 const TypePtr* atp = TypeRawPtr::BOTTOM;
4035
4036 // One or two coalesced stores to plop down.
4037 Node* st[2];
4038 intptr_t off[2];
4039 int nst = 0;
4040 if (!split) {
4041 ++new_long;
4042 off[nst] = offset;
4043 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
4044 phase->longcon(con), T_LONG, MemNode::unordered);
4045 } else {
4046 // Omit either if it is a zero.
4047 if (con0 != 0) {
4048 ++new_int;
4049 off[nst] = offset;
4050 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
4051 phase->intcon(con0), T_INT, MemNode::unordered);
4052 }
4053 if (con1 != 0) {
4054 ++new_int;
4055 offset += BytesPerInt;
4056 adr = make_raw_address(offset, phase);
4057 off[nst] = offset;
4058 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
4059 phase->intcon(con1), T_INT, MemNode::unordered);
4060 }
4061 }
4062
4063 // Insert second store first, then the first before the second.
4064 // Insert each one just before any overlapping non-constant stores.
4065 while (nst > 0) {
4066 Node* st1 = st[--nst];
4067 C->copy_node_notes_to(st1, old);
4068 st1 = phase->transform(st1);
4069 offset = off[nst];
4070 assert(offset >= header_size, "do not smash header");
4071 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
4072 guarantee(ins_idx != 0, "must re-insert constant store");
4073 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
4074 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
4075 set_req(--ins_idx, st1);
4076 else
4077 ins_req(ins_idx, st1);
4078 }
4079 }
4080
4081 if (PrintCompilation && WizardMode)
4082 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
4083 old_subword, old_long, new_int, new_long);
4084 if (C->log() != NULL)
4085 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
4086 old_subword, old_long, new_int, new_long);
4087
4088 // Clean up any remaining occurrences of zmem:
4089 remove_extra_zeroes();
4090 }
4091
4092 // Explore forward from in(start) to find the first fully initialized
4093 // word, and return its offset. Skip groups of subword stores which
4094 // together initialize full words. If in(start) is itself part of a
4095 // fully initialized word, return the offset of in(start). If there
4096 // are no following full-word stores, or if something is fishy, return
4097 // a negative value.
4098 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
4099 int int_map = 0;
4100 intptr_t int_map_off = 0;
4101 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
4102
4103 for (uint i = start, limit = req(); i < limit; i++) {
4104 Node* st = in(i);
4105
4106 intptr_t st_off = get_store_offset(st, phase);
4107 if (st_off < 0) break; // return conservative answer
4108
4109 int st_size = st->as_Store()->memory_size();
4110 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
4111 return st_off; // we found a complete word init
4112 }
4113
4114 // update the map:
4115
4116 intptr_t this_int_off = align_down(st_off, BytesPerInt);
4117 if (this_int_off != int_map_off) {
4118 // reset the map:
4119 int_map = 0;
4120 int_map_off = this_int_off;
4121 }
4122
4123 int subword_off = st_off - this_int_off;
4124 int_map |= right_n_bits(st_size) << subword_off;
4125 if ((int_map & FULL_MAP) == FULL_MAP) {
4126 return this_int_off; // we found a complete word init
4127 }
4128
4129 // Did this store hit or cross the word boundary?
4130 intptr_t next_int_off = align_down(st_off + st_size, BytesPerInt);
4131 if (next_int_off == this_int_off + BytesPerInt) {
4132 // We passed the current int, without fully initializing it.
4133 int_map_off = next_int_off;
4134 int_map >>= BytesPerInt;
4135 } else if (next_int_off > this_int_off + BytesPerInt) {
4136 // We passed the current and next int.
4137 return this_int_off + BytesPerInt;
4138 }
4139 }
4140
4141 return -1;
4142 }
4143
4144
4145 // Called when the associated AllocateNode is expanded into CFG.
4146 // At this point, we may perform additional optimizations.
4147 // Linearize the stores by ascending offset, to make memory
4148 // activity as coherent as possible.
4149 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
4150 intptr_t header_size,
4151 Node* size_in_bytes,
4152 PhaseIterGVN* phase) {
4153 assert(!is_complete(), "not already complete");
4154 assert(stores_are_sane(phase), "");
4155 assert(allocation() != NULL, "must be present");
4156
4157 remove_extra_zeroes();
4158
4159 if (ReduceFieldZeroing || ReduceBulkZeroing)
4160 // reduce instruction count for common initialization patterns
4161 coalesce_subword_stores(header_size, size_in_bytes, phase);
4162
4163 Node* zmem = zero_memory(); // initially zero memory state
4164 Node* inits = zmem; // accumulating a linearized chain of inits
4165 #ifdef ASSERT
4166 intptr_t first_offset = allocation()->minimum_header_size();
4167 intptr_t last_init_off = first_offset; // previous init offset
4168 intptr_t last_init_end = first_offset; // previous init offset+size
4169 intptr_t last_tile_end = first_offset; // previous tile offset+size
4170 #endif
4171 intptr_t zeroes_done = header_size;
4172
4173 bool do_zeroing = true; // we might give up if inits are very sparse
4174 int big_init_gaps = 0; // how many large gaps have we seen?
4175
4176 if (UseTLAB && ZeroTLAB) do_zeroing = false;
4177 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
4178
4179 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
4180 Node* st = in(i);
4181 intptr_t st_off = get_store_offset(st, phase);
4182 if (st_off < 0)
4183 break; // unknown junk in the inits
4184 if (st->in(MemNode::Memory) != zmem)
4185 break; // complicated store chains somehow in list
4186
4187 int st_size = st->as_Store()->memory_size();
4188 intptr_t next_init_off = st_off + st_size;
4189
4190 if (do_zeroing && zeroes_done < next_init_off) {
4191 // See if this store needs a zero before it or under it.
4192 intptr_t zeroes_needed = st_off;
4193
4194 if (st_size < BytesPerInt) {
4195 // Look for subword stores which only partially initialize words.
4196 // If we find some, we must lay down some word-level zeroes first,
4197 // underneath the subword stores.
4198 //
4199 // Examples:
4200 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
4201 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
4202 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
4203 //
4204 // Note: coalesce_subword_stores may have already done this,
4205 // if it was prompted by constant non-zero subword initializers.
4206 // But this case can still arise with non-constant stores.
4207
4208 intptr_t next_full_store = find_next_fullword_store(i, phase);
4209
4210 // In the examples above:
4211 // in(i) p q r s x y z
4212 // st_off 12 13 14 15 12 13 14
4213 // st_size 1 1 1 1 1 1 1
4214 // next_full_s. 12 16 16 16 16 16 16
4215 // z's_done 12 16 16 16 12 16 12
4216 // z's_needed 12 16 16 16 16 16 16
4217 // zsize 0 0 0 0 4 0 4
4218 if (next_full_store < 0) {
4219 // Conservative tack: Zero to end of current word.
4220 zeroes_needed = align_up(zeroes_needed, BytesPerInt);
4221 } else {
4222 // Zero to beginning of next fully initialized word.
4223 // Or, don't zero at all, if we are already in that word.
4224 assert(next_full_store >= zeroes_needed, "must go forward");
4225 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
4226 zeroes_needed = next_full_store;
4227 }
4228 }
4229
4230 if (zeroes_needed > zeroes_done) {
4231 intptr_t zsize = zeroes_needed - zeroes_done;
4232 // Do some incremental zeroing on rawmem, in parallel with inits.
4233 zeroes_done = align_down(zeroes_done, BytesPerInt);
4234 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
4235 zeroes_done, zeroes_needed,
4236 phase);
4237 zeroes_done = zeroes_needed;
4238 if (zsize > InitArrayShortSize && ++big_init_gaps > 2)
4239 do_zeroing = false; // leave the hole, next time
4240 }
4241 }
4242
4243 // Collect the store and move on:
4244 phase->replace_input_of(st, MemNode::Memory, inits);
4245 inits = st; // put it on the linearized chain
4246 set_req(i, zmem); // unhook from previous position
4247
4248 if (zeroes_done == st_off)
4249 zeroes_done = next_init_off;
4250
4251 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
4252
4253 #ifdef ASSERT
4254 // Various order invariants. Weaker than stores_are_sane because
4255 // a large constant tile can be filled in by smaller non-constant stores.
4256 assert(st_off >= last_init_off, "inits do not reverse");
4257 last_init_off = st_off;
4258 const Type* val = NULL;
4259 if (st_size >= BytesPerInt &&
4260 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
4261 (int)val->basic_type() < (int)T_OBJECT) {
4262 assert(st_off >= last_tile_end, "tiles do not overlap");
4263 assert(st_off >= last_init_end, "tiles do not overwrite inits");
4264 last_tile_end = MAX2(last_tile_end, next_init_off);
4265 } else {
4266 intptr_t st_tile_end = align_up(next_init_off, BytesPerLong);
4267 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
4268 assert(st_off >= last_init_end, "inits do not overlap");
4269 last_init_end = next_init_off; // it's a non-tile
4270 }
4271 #endif //ASSERT
4272 }
4273
4274 remove_extra_zeroes(); // clear out all the zmems left over
4275 add_req(inits);
4276
4277 if (!(UseTLAB && ZeroTLAB)) {
4278 // If anything remains to be zeroed, zero it all now.
4279 zeroes_done = align_down(zeroes_done, BytesPerInt);
4280 // if it is the last unused 4 bytes of an instance, forget about it
4281 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
4282 if (zeroes_done + BytesPerLong >= size_limit) {
4283 AllocateNode* alloc = allocation();
4284 assert(alloc != NULL, "must be present");
4285 if (alloc != NULL && alloc->Opcode() == Op_Allocate) {
4286 Node* klass_node = alloc->in(AllocateNode::KlassNode);
4287 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass();
4288 if (zeroes_done == k->layout_helper())
4289 zeroes_done = size_limit;
4290 }
4291 }
4292 if (zeroes_done < size_limit) {
4293 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
4294 zeroes_done, size_in_bytes, phase);
4295 }
4296 }
4297
4298 set_complete(phase);
4299 return rawmem;
4300 }
4301
4302
4303 #ifdef ASSERT
4304 bool InitializeNode::stores_are_sane(PhaseTransform* phase) {
4305 if (is_complete())
4306 return true; // stores could be anything at this point
4307 assert(allocation() != NULL, "must be present");
4308 intptr_t last_off = allocation()->minimum_header_size();
4309 for (uint i = InitializeNode::RawStores; i < req(); i++) {
4310 Node* st = in(i);
4311 intptr_t st_off = get_store_offset(st, phase);
4312 if (st_off < 0) continue; // ignore dead garbage
4313 if (last_off > st_off) {
4314 tty->print_cr("*** bad store offset at %d: " INTX_FORMAT " > " INTX_FORMAT, i, last_off, st_off);
4315 this->dump(2);
4316 assert(false, "ascending store offsets");
4317 return false;
4318 }
4319 last_off = st_off + st->as_Store()->memory_size();
4320 }
4321 return true;
4322 }
4323 #endif //ASSERT
4324
4325
4326
4327
4328 //============================MergeMemNode=====================================
4329 //
4330 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
4331 // contributing store or call operations. Each contributor provides the memory
4332 // state for a particular "alias type" (see Compile::alias_type). For example,
4333 // if a MergeMem has an input X for alias category #6, then any memory reference
4334 // to alias category #6 may use X as its memory state input, as an exact equivalent
4335 // to using the MergeMem as a whole.
4336 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
4337 //
4338 // (Here, the <N> notation gives the index of the relevant adr_type.)
4339 //
4340 // In one special case (and more cases in the future), alias categories overlap.
4341 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
4342 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
4343 // it is exactly equivalent to that state W:
4344 // MergeMem(<Bot>: W) <==> W
4345 //
4346 // Usually, the merge has more than one input. In that case, where inputs
4347 // overlap (i.e., one is Bot), the narrower alias type determines the memory
4348 // state for that type, and the wider alias type (Bot) fills in everywhere else:
4349 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
4350 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
4351 //
4352 // A merge can take a "wide" memory state as one of its narrow inputs.
4353 // This simply means that the merge observes out only the relevant parts of
4354 // the wide input. That is, wide memory states arriving at narrow merge inputs
4355 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
4356 //
4357 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
4358 // and that memory slices "leak through":
4359 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
4360 //
4361 // But, in such a cascade, repeated memory slices can "block the leak":
4362 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
4363 //
4364 // In the last example, Y is not part of the combined memory state of the
4365 // outermost MergeMem. The system must, of course, prevent unschedulable
4366 // memory states from arising, so you can be sure that the state Y is somehow
4367 // a precursor to state Y'.
4368 //
4369 //
4370 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
4371 // of each MergeMemNode array are exactly the numerical alias indexes, including
4372 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
4373 // Compile::alias_type (and kin) produce and manage these indexes.
4374 //
4375 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
4376 // (Note that this provides quick access to the top node inside MergeMem methods,
4377 // without the need to reach out via TLS to Compile::current.)
4378 //
4379 // As a consequence of what was just described, a MergeMem that represents a full
4380 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
4381 // containing all alias categories.
4382 //
4383 // MergeMem nodes never (?) have control inputs, so in(0) is NULL.
4384 //
4385 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
4386 // a memory state for the alias type <N>, or else the top node, meaning that
4387 // there is no particular input for that alias type. Note that the length of
4388 // a MergeMem is variable, and may be extended at any time to accommodate new
4389 // memory states at larger alias indexes. When merges grow, they are of course
4390 // filled with "top" in the unused in() positions.
4391 //
4392 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
4393 // (Top was chosen because it works smoothly with passes like GCM.)
4394 //
4395 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
4396 // the type of random VM bits like TLS references.) Since it is always the
4397 // first non-Bot memory slice, some low-level loops use it to initialize an
4398 // index variable: for (i = AliasIdxRaw; i < req(); i++).
4399 //
4400 //
4401 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
4402 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
4403 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
4404 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
4405 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
4406 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
4407 //
4408 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
4409 // really that different from the other memory inputs. An abbreviation called
4410 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
4411 //
4412 //
4413 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
4414 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
4415 // that "emerges though" the base memory will be marked as excluding the alias types
4416 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
4417 //
4418 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
4419 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
4420 //
4421 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
4422 // (It is currently unimplemented.) As you can see, the resulting merge is
4423 // actually a disjoint union of memory states, rather than an overlay.
4424 //
4425
4426 //------------------------------MergeMemNode-----------------------------------
4427 Node* MergeMemNode::make_empty_memory() {
4428 Node* empty_memory = (Node*) Compile::current()->top();
4429 assert(empty_memory->is_top(), "correct sentinel identity");
4430 return empty_memory;
4431 }
4432
4433 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
4434 init_class_id(Class_MergeMem);
4435 // all inputs are nullified in Node::Node(int)
4436 // set_input(0, NULL); // no control input
4437
4438 // Initialize the edges uniformly to top, for starters.
4439 Node* empty_mem = make_empty_memory();
4440 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
4441 init_req(i,empty_mem);
4442 }
4443 assert(empty_memory() == empty_mem, "");
4444
4445 if( new_base != NULL && new_base->is_MergeMem() ) {
4446 MergeMemNode* mdef = new_base->as_MergeMem();
4447 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
4448 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
4449 mms.set_memory(mms.memory2());
4450 }
4451 assert(base_memory() == mdef->base_memory(), "");
4452 } else {
4453 set_base_memory(new_base);
4454 }
4455 }
4456
4457 // Make a new, untransformed MergeMem with the same base as 'mem'.
4458 // If mem is itself a MergeMem, populate the result with the same edges.
4459 MergeMemNode* MergeMemNode::make(Node* mem) {
4460 return new MergeMemNode(mem);
4461 }
4462
4463 //------------------------------cmp--------------------------------------------
4464 uint MergeMemNode::hash() const { return NO_HASH; }
4465 uint MergeMemNode::cmp( const Node &n ) const {
4466 return (&n == this); // Always fail except on self
4467 }
4468
4469 //------------------------------Identity---------------------------------------
4470 Node* MergeMemNode::Identity(PhaseGVN* phase) {
4471 // Identity if this merge point does not record any interesting memory
4472 // disambiguations.
4473 Node* base_mem = base_memory();
4474 Node* empty_mem = empty_memory();
4475 if (base_mem != empty_mem) { // Memory path is not dead?
4476 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4477 Node* mem = in(i);
4478 if (mem != empty_mem && mem != base_mem) {
4479 return this; // Many memory splits; no change
4480 }
4481 }
4482 }
4483 return base_mem; // No memory splits; ID on the one true input
4484 }
4485
4486 //------------------------------Ideal------------------------------------------
4487 // This method is invoked recursively on chains of MergeMem nodes
4488 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4489 // Remove chain'd MergeMems
4490 //
4491 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
4492 // relative to the "in(Bot)". Since we are patching both at the same time,
4493 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
4494 // but rewrite each "in(i)" relative to the new "in(Bot)".
4495 Node *progress = NULL;
4496
4497
4498 Node* old_base = base_memory();
4499 Node* empty_mem = empty_memory();
4500 if (old_base == empty_mem)
4501 return NULL; // Dead memory path.
4502
4503 MergeMemNode* old_mbase;
4504 if (old_base != NULL && old_base->is_MergeMem())
4505 old_mbase = old_base->as_MergeMem();
4506 else
4507 old_mbase = NULL;
4508 Node* new_base = old_base;
4509
4510 // simplify stacked MergeMems in base memory
4511 if (old_mbase) new_base = old_mbase->base_memory();
4512
4513 // the base memory might contribute new slices beyond my req()
4514 if (old_mbase) grow_to_match(old_mbase);
4515
4516 // Look carefully at the base node if it is a phi.
4517 PhiNode* phi_base;
4518 if (new_base != NULL && new_base->is_Phi())
4519 phi_base = new_base->as_Phi();
4520 else
4521 phi_base = NULL;
4522
4523 Node* phi_reg = NULL;
4524 uint phi_len = (uint)-1;
4525 if (phi_base != NULL && !phi_base->is_copy()) {
4526 // do not examine phi if degraded to a copy
4527 phi_reg = phi_base->region();
4528 phi_len = phi_base->req();
4529 // see if the phi is unfinished
4530 for (uint i = 1; i < phi_len; i++) {
4531 if (phi_base->in(i) == NULL) {
4532 // incomplete phi; do not look at it yet!
4533 phi_reg = NULL;
4534 phi_len = (uint)-1;
4535 break;
4536 }
4537 }
4538 }
4539
4540 // Note: We do not call verify_sparse on entry, because inputs
4541 // can normalize to the base_memory via subsume_node or similar
4542 // mechanisms. This method repairs that damage.
4543
4544 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
4545
4546 // Look at each slice.
4547 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4548 Node* old_in = in(i);
4549 // calculate the old memory value
4550 Node* old_mem = old_in;
4551 if (old_mem == empty_mem) old_mem = old_base;
4552 assert(old_mem == memory_at(i), "");
4553
4554 // maybe update (reslice) the old memory value
4555
4556 // simplify stacked MergeMems
4557 Node* new_mem = old_mem;
4558 MergeMemNode* old_mmem;
4559 if (old_mem != NULL && old_mem->is_MergeMem())
4560 old_mmem = old_mem->as_MergeMem();
4561 else
4562 old_mmem = NULL;
4563 if (old_mmem == this) {
4564 // This can happen if loops break up and safepoints disappear.
4565 // A merge of BotPtr (default) with a RawPtr memory derived from a
4566 // safepoint can be rewritten to a merge of the same BotPtr with
4567 // the BotPtr phi coming into the loop. If that phi disappears
4568 // also, we can end up with a self-loop of the mergemem.
4569 // In general, if loops degenerate and memory effects disappear,
4570 // a mergemem can be left looking at itself. This simply means
4571 // that the mergemem's default should be used, since there is
4572 // no longer any apparent effect on this slice.
4573 // Note: If a memory slice is a MergeMem cycle, it is unreachable
4574 // from start. Update the input to TOP.
4575 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
4576 }
4577 else if (old_mmem != NULL) {
4578 new_mem = old_mmem->memory_at(i);
4579 }
4580 // else preceding memory was not a MergeMem
4581
4582 // replace equivalent phis (unfortunately, they do not GVN together)
4583 if (new_mem != NULL && new_mem != new_base &&
4584 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) {
4585 if (new_mem->is_Phi()) {
4586 PhiNode* phi_mem = new_mem->as_Phi();
4587 for (uint i = 1; i < phi_len; i++) {
4588 if (phi_base->in(i) != phi_mem->in(i)) {
4589 phi_mem = NULL;
4590 break;
4591 }
4592 }
4593 if (phi_mem != NULL) {
4594 // equivalent phi nodes; revert to the def
4595 new_mem = new_base;
4596 }
4597 }
4598 }
4599
4600 // maybe store down a new value
4601 Node* new_in = new_mem;
4602 if (new_in == new_base) new_in = empty_mem;
4603
4604 if (new_in != old_in) {
4605 // Warning: Do not combine this "if" with the previous "if"
4606 // A memory slice might have be be rewritten even if it is semantically
4607 // unchanged, if the base_memory value has changed.
4608 set_req(i, new_in);
4609 progress = this; // Report progress
4610 }
4611 }
4612
4613 if (new_base != old_base) {
4614 set_req(Compile::AliasIdxBot, new_base);
4615 // Don't use set_base_memory(new_base), because we need to update du.
4616 assert(base_memory() == new_base, "");
4617 progress = this;
4618 }
4619
4620 if( base_memory() == this ) {
4621 // a self cycle indicates this memory path is dead
4622 set_req(Compile::AliasIdxBot, empty_mem);
4623 }
4624
4625 // Resolve external cycles by calling Ideal on a MergeMem base_memory
4626 // Recursion must occur after the self cycle check above
4627 if( base_memory()->is_MergeMem() ) {
4628 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
4629 Node *m = phase->transform(new_mbase); // Rollup any cycles
4630 if( m != NULL &&
4631 (m->is_top() ||
4632 (m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem)) ) {
4633 // propagate rollup of dead cycle to self
4634 set_req(Compile::AliasIdxBot, empty_mem);
4635 }
4636 }
4637
4638 if( base_memory() == empty_mem ) {
4639 progress = this;
4640 // Cut inputs during Parse phase only.
4641 // During Optimize phase a dead MergeMem node will be subsumed by Top.
4642 if( !can_reshape ) {
4643 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4644 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
4645 }
4646 }
4647 }
4648
4649 if( !progress && base_memory()->is_Phi() && can_reshape ) {
4650 // Check if PhiNode::Ideal's "Split phis through memory merges"
4651 // transform should be attempted. Look for this->phi->this cycle.
4652 uint merge_width = req();
4653 if (merge_width > Compile::AliasIdxRaw) {
4654 PhiNode* phi = base_memory()->as_Phi();
4655 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
4656 if (phi->in(i) == this) {
4657 phase->is_IterGVN()->_worklist.push(phi);
4658 break;
4659 }
4660 }
4661 }
4662 }
4663
4664 assert(progress || verify_sparse(), "please, no dups of base");
4665 return progress;
4666 }
4667
4668 //-------------------------set_base_memory-------------------------------------
4669 void MergeMemNode::set_base_memory(Node *new_base) {
4670 Node* empty_mem = empty_memory();
4671 set_req(Compile::AliasIdxBot, new_base);
4672 assert(memory_at(req()) == new_base, "must set default memory");
4673 // Clear out other occurrences of new_base:
4674 if (new_base != empty_mem) {
4675 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4676 if (in(i) == new_base) set_req(i, empty_mem);
4677 }
4678 }
4679 }
4680
4681 //------------------------------out_RegMask------------------------------------
4682 const RegMask &MergeMemNode::out_RegMask() const {
4683 return RegMask::Empty;
4684 }
4685
4686 //------------------------------dump_spec--------------------------------------
4687 #ifndef PRODUCT
4688 void MergeMemNode::dump_spec(outputStream *st) const {
4689 st->print(" {");
4690 Node* base_mem = base_memory();
4691 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
4692 Node* mem = (in(i) != NULL) ? memory_at(i) : base_mem;
4693 if (mem == base_mem) { st->print(" -"); continue; }
4694 st->print( " N%d:", mem->_idx );
4695 Compile::current()->get_adr_type(i)->dump_on(st);
4696 }
4697 st->print(" }");
4698 }
4699 #endif // !PRODUCT
4700
4701
4702 #ifdef ASSERT
4703 static bool might_be_same(Node* a, Node* b) {
4704 if (a == b) return true;
4705 if (!(a->is_Phi() || b->is_Phi())) return false;
4706 // phis shift around during optimization
4707 return true; // pretty stupid...
4708 }
4709
4710 // verify a narrow slice (either incoming or outgoing)
4711 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
4712 if (!VerifyAliases) return; // don't bother to verify unless requested
4713 if (VMError::is_error_reported()) return; // muzzle asserts when debugging an error
4714 if (Node::in_dump()) return; // muzzle asserts when printing
4715 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
4716 assert(n != NULL, "");
4717 // Elide intervening MergeMem's
4718 while (n->is_MergeMem()) {
4719 n = n->as_MergeMem()->memory_at(alias_idx);
4720 }
4721 Compile* C = Compile::current();
4722 const TypePtr* n_adr_type = n->adr_type();
4723 if (n == m->empty_memory()) {
4724 // Implicit copy of base_memory()
4725 } else if (n_adr_type != TypePtr::BOTTOM) {
4726 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type");
4727 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
4728 } else {
4729 // A few places like make_runtime_call "know" that VM calls are narrow,
4730 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
4731 bool expected_wide_mem = false;
4732 if (n == m->base_memory()) {
4733 expected_wide_mem = true;
4734 } else if (alias_idx == Compile::AliasIdxRaw ||
4735 n == m->memory_at(Compile::AliasIdxRaw)) {
4736 expected_wide_mem = true;
4737 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
4738 // memory can "leak through" calls on channels that
4739 // are write-once. Allow this also.
4740 expected_wide_mem = true;
4741 }
4742 assert(expected_wide_mem, "expected narrow slice replacement");
4743 }
4744 }
4745 #else // !ASSERT
4746 #define verify_memory_slice(m,i,n) (void)(0) // PRODUCT version is no-op
4747 #endif
4748
4749
4750 //-----------------------------memory_at---------------------------------------
4751 Node* MergeMemNode::memory_at(uint alias_idx) const {
4752 assert(alias_idx >= Compile::AliasIdxRaw ||
4753 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0,
4754 "must avoid base_memory and AliasIdxTop");
4755
4756 // Otherwise, it is a narrow slice.
4757 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
4758 Compile *C = Compile::current();
4759 if (is_empty_memory(n)) {
4760 // the array is sparse; empty slots are the "top" node
4761 n = base_memory();
4762 assert(Node::in_dump()
4763 || n == NULL || n->bottom_type() == Type::TOP
4764 || n->adr_type() == NULL // address is TOP
4765 || n->adr_type() == TypePtr::BOTTOM
4766 || n->adr_type() == TypeRawPtr::BOTTOM
4767 || Compile::current()->AliasLevel() == 0,
4768 "must be a wide memory");
4769 // AliasLevel == 0 if we are organizing the memory states manually.
4770 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
4771 } else {
4772 // make sure the stored slice is sane
4773 #ifdef ASSERT
4774 if (VMError::is_error_reported() || Node::in_dump()) {
4775 } else if (might_be_same(n, base_memory())) {
4776 // Give it a pass: It is a mostly harmless repetition of the base.
4777 // This can arise normally from node subsumption during optimization.
4778 } else {
4779 verify_memory_slice(this, alias_idx, n);
4780 }
4781 #endif
4782 }
4783 return n;
4784 }
4785
4786 //---------------------------set_memory_at-------------------------------------
4787 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
4788 verify_memory_slice(this, alias_idx, n);
4789 Node* empty_mem = empty_memory();
4790 if (n == base_memory()) n = empty_mem; // collapse default
4791 uint need_req = alias_idx+1;
4792 if (req() < need_req) {
4793 if (n == empty_mem) return; // already the default, so do not grow me
4794 // grow the sparse array
4795 do {
4796 add_req(empty_mem);
4797 } while (req() < need_req);
4798 }
4799 set_req( alias_idx, n );
4800 }
4801
4802
4803
4804 //--------------------------iteration_setup------------------------------------
4805 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
4806 if (other != NULL) {
4807 grow_to_match(other);
4808 // invariant: the finite support of mm2 is within mm->req()
4809 #ifdef ASSERT
4810 for (uint i = req(); i < other->req(); i++) {
4811 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
4812 }
4813 #endif
4814 }
4815 // Replace spurious copies of base_memory by top.
4816 Node* base_mem = base_memory();
4817 if (base_mem != NULL && !base_mem->is_top()) {
4818 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
4819 if (in(i) == base_mem)
4820 set_req(i, empty_memory());
4821 }
4822 }
4823 }
4824
4825 //---------------------------grow_to_match-------------------------------------
4826 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
4827 Node* empty_mem = empty_memory();
4828 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
4829 // look for the finite support of the other memory
4830 for (uint i = other->req(); --i >= req(); ) {
4831 if (other->in(i) != empty_mem) {
4832 uint new_len = i+1;
4833 while (req() < new_len) add_req(empty_mem);
4834 break;
4835 }
4836 }
4837 }
4838
4839 //---------------------------verify_sparse-------------------------------------
4840 #ifndef PRODUCT
4841 bool MergeMemNode::verify_sparse() const {
4842 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
4843 Node* base_mem = base_memory();
4844 // The following can happen in degenerate cases, since empty==top.
4845 if (is_empty_memory(base_mem)) return true;
4846 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4847 assert(in(i) != NULL, "sane slice");
4848 if (in(i) == base_mem) return false; // should have been the sentinel value!
4849 }
4850 return true;
4851 }
4852
4853 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
4854 Node* n;
4855 n = mm->in(idx);
4856 if (mem == n) return true; // might be empty_memory()
4857 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
4858 if (mem == n) return true;
4859 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) {
4860 if (mem == n) return true;
4861 if (n == NULL) break;
4862 }
4863 return false;
4864 }
4865 #endif // !PRODUCT