1 /*
2 * Copyright (c) 1997, 2021, 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 "ci/ciFlatArrayKlass.hpp"
27 #include "classfile/javaClasses.hpp"
28 #include "classfile/systemDictionary.hpp"
29 #include "compiler/compileLog.hpp"
30 #include "gc/shared/barrierSet.hpp"
31 #include "gc/shared/c2/barrierSetC2.hpp"
32 #include "gc/shared/tlab_globals.hpp"
33 #include "memory/allocation.inline.hpp"
34 #include "memory/resourceArea.hpp"
35 #include "oops/objArrayKlass.hpp"
36 #include "opto/addnode.hpp"
37 #include "opto/arraycopynode.hpp"
38 #include "opto/cfgnode.hpp"
39 #include "opto/regalloc.hpp"
40 #include "opto/compile.hpp"
41 #include "opto/connode.hpp"
42 #include "opto/convertnode.hpp"
43 #include "opto/inlinetypenode.hpp"
44 #include "opto/loopnode.hpp"
45 #include "opto/machnode.hpp"
46 #include "opto/matcher.hpp"
47 #include "opto/memnode.hpp"
48 #include "opto/mulnode.hpp"
49 #include "opto/narrowptrnode.hpp"
50 #include "opto/phaseX.hpp"
51 #include "opto/regmask.hpp"
52 #include "opto/rootnode.hpp"
53 #include "opto/vectornode.hpp"
54 #include "utilities/align.hpp"
55 #include "utilities/copy.hpp"
56 #include "utilities/macros.hpp"
57 #include "utilities/powerOfTwo.hpp"
58 #include "utilities/vmError.hpp"
59
60 // Portions of code courtesy of Clifford Click
61
62 // Optimization - Graph Style
63
64 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st);
65
66 //=============================================================================
67 uint MemNode::size_of() const { return sizeof(*this); }
68
69 const TypePtr *MemNode::adr_type() const {
70 Node* adr = in(Address);
71 if (adr == NULL) return NULL; // node is dead
72 const TypePtr* cross_check = NULL;
73 DEBUG_ONLY(cross_check = _adr_type);
74 return calculate_adr_type(adr->bottom_type(), cross_check);
75 }
76
77 bool MemNode::check_if_adr_maybe_raw(Node* adr) {
78 if (adr != NULL) {
79 if (adr->bottom_type()->base() == Type::RawPtr || adr->bottom_type()->base() == Type::AnyPtr) {
80 return true;
81 }
82 }
83 return false;
84 }
85
86 #ifndef PRODUCT
87 void MemNode::dump_spec(outputStream *st) const {
88 if (in(Address) == NULL) return; // node is dead
89 #ifndef ASSERT
90 // fake the missing field
91 const TypePtr* _adr_type = NULL;
92 if (in(Address) != NULL)
93 _adr_type = in(Address)->bottom_type()->isa_ptr();
94 #endif
95 dump_adr_type(this, _adr_type, st);
96
97 Compile* C = Compile::current();
98 if (C->alias_type(_adr_type)->is_volatile()) {
99 st->print(" Volatile!");
100 }
101 if (_unaligned_access) {
102 st->print(" unaligned");
103 }
104 if (_mismatched_access) {
105 st->print(" mismatched");
106 }
107 if (_unsafe_access) {
108 st->print(" unsafe");
109 }
110 }
111
112 void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) {
113 st->print(" @");
114 if (adr_type == NULL) {
115 st->print("NULL");
116 } else {
117 adr_type->dump_on(st);
118 Compile* C = Compile::current();
119 Compile::AliasType* atp = NULL;
120 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type);
121 if (atp == NULL)
122 st->print(", idx=?\?;");
123 else if (atp->index() == Compile::AliasIdxBot)
124 st->print(", idx=Bot;");
125 else if (atp->index() == Compile::AliasIdxTop)
126 st->print(", idx=Top;");
127 else if (atp->index() == Compile::AliasIdxRaw)
128 st->print(", idx=Raw;");
129 else {
130 ciField* field = atp->field();
131 if (field) {
132 st->print(", name=");
133 field->print_name_on(st);
134 }
135 st->print(", idx=%d;", atp->index());
136 }
137 }
138 }
139
140 extern void print_alias_types();
141
142 #endif
143
144 Node *MemNode::optimize_simple_memory_chain(Node *mchain, const TypeOopPtr *t_oop, Node *load, PhaseGVN *phase) {
145 assert((t_oop != NULL), "sanity");
146 bool is_instance = t_oop->is_known_instance_field();
147 bool is_boxed_value_load = t_oop->is_ptr_to_boxed_value() &&
148 (load != NULL) && load->is_Load() &&
149 (phase->is_IterGVN() != NULL);
150 if (!(is_instance || is_boxed_value_load))
151 return mchain; // don't try to optimize non-instance types
152 uint instance_id = t_oop->instance_id();
153 Node *start_mem = phase->C->start()->proj_out_or_null(TypeFunc::Memory);
154 Node *prev = NULL;
155 Node *result = mchain;
156 while (prev != result) {
157 prev = result;
158 if (result == start_mem)
159 break; // hit one of our sentinels
160 // skip over a call which does not affect this memory slice
161 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {
162 Node *proj_in = result->in(0);
163 if (proj_in->is_Allocate() && proj_in->_idx == instance_id) {
164 break; // hit one of our sentinels
165 } else if (proj_in->is_Call()) {
166 // ArrayCopyNodes processed here as well
167 CallNode *call = proj_in->as_Call();
168 if (!call->may_modify(t_oop, phase)) { // returns false for instances
169 result = call->in(TypeFunc::Memory);
170 }
171 } else if (proj_in->is_Initialize()) {
172 AllocateNode* alloc = proj_in->as_Initialize()->allocation();
173 // Stop if this is the initialization for the object instance which
174 // contains this memory slice, otherwise skip over it.
175 if ((alloc == NULL) || (alloc->_idx == instance_id)) {
176 break;
177 }
178 if (is_instance) {
179 result = proj_in->in(TypeFunc::Memory);
180 } else if (is_boxed_value_load) {
181 Node* klass = alloc->in(AllocateNode::KlassNode);
182 const TypeKlassPtr* tklass = phase->type(klass)->is_klassptr();
183 if (tklass->klass_is_exact() && !tklass->klass()->equals(t_oop->klass())) {
184 result = proj_in->in(TypeFunc::Memory); // not related allocation
185 }
186 }
187 } else if (proj_in->is_MemBar()) {
188 ArrayCopyNode* ac = NULL;
189 if (ArrayCopyNode::may_modify(t_oop, proj_in->as_MemBar(), phase, ac)) {
190 break;
191 }
192 result = proj_in->in(TypeFunc::Memory);
193 } else {
194 assert(false, "unexpected projection");
195 }
196 } else if (result->is_ClearArray()) {
197 if (!is_instance || !ClearArrayNode::step_through(&result, instance_id, phase)) {
198 // Can not bypass initialization of the instance
199 // we are looking for.
200 break;
201 }
202 // Otherwise skip it (the call updated 'result' value).
203 } else if (result->is_MergeMem()) {
204 result = step_through_mergemem(phase, result->as_MergeMem(), t_oop, NULL, tty);
205 }
206 }
207 return result;
208 }
209
210 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, Node *load, PhaseGVN *phase) {
211 const TypeOopPtr* t_oop = t_adr->isa_oopptr();
212 if (t_oop == NULL)
213 return mchain; // don't try to optimize non-oop types
214 Node* result = optimize_simple_memory_chain(mchain, t_oop, load, phase);
215 bool is_instance = t_oop->is_known_instance_field();
216 PhaseIterGVN *igvn = phase->is_IterGVN();
217 if (is_instance && igvn != NULL && result->is_Phi()) {
218 PhiNode *mphi = result->as_Phi();
219 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
220 const TypePtr *t = mphi->adr_type();
221 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
222 (t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
223 t->is_oopptr()->cast_to_exactness(true)
224 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
225 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop)) {
226 // clone the Phi with our address type
227 result = mphi->split_out_instance(t_adr, igvn);
228 } else {
229 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain");
230 }
231 }
232 return result;
233 }
234
235 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) {
236 uint alias_idx = phase->C->get_alias_index(tp);
237 Node *mem = mmem;
238 #ifdef ASSERT
239 {
240 // Check that current type is consistent with the alias index used during graph construction
241 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
242 bool consistent = adr_check == NULL || adr_check->empty() ||
243 phase->C->must_alias(adr_check, alias_idx );
244 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
245 if( !consistent && adr_check != NULL && !adr_check->empty() &&
246 tp->isa_aryptr() && tp->offset() == Type::OffsetBot &&
247 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot &&
248 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() ||
249 adr_check->offset() == oopDesc::klass_offset_in_bytes() ||
250 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) {
251 // don't assert if it is dead code.
252 consistent = true;
253 }
254 if( !consistent ) {
255 st->print("alias_idx==%d, adr_check==", alias_idx);
256 if( adr_check == NULL ) {
257 st->print("NULL");
258 } else {
259 adr_check->dump();
260 }
261 st->cr();
262 print_alias_types();
263 assert(consistent, "adr_check must match alias idx");
264 }
265 }
266 #endif
267 // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally
268 // means an array I have not precisely typed yet. Do not do any
269 // alias stuff with it any time soon.
270 const TypeOopPtr *toop = tp->isa_oopptr();
271 if( tp->base() != Type::AnyPtr &&
272 !(toop &&
273 toop->klass() != NULL &&
274 toop->klass()->is_java_lang_Object() &&
275 toop->offset() == Type::OffsetBot) ) {
276 // compress paths and change unreachable cycles to TOP
277 // If not, we can update the input infinitely along a MergeMem cycle
278 // Equivalent code in PhiNode::Ideal
279 Node* m = phase->transform(mmem);
280 // If transformed to a MergeMem, get the desired slice
281 // Otherwise the returned node represents memory for every slice
282 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
283 // Update input if it is progress over what we have now
284 }
285 return mem;
286 }
287
288 //--------------------------Ideal_common---------------------------------------
289 // Look for degenerate control and memory inputs. Bypass MergeMem inputs.
290 // Unhook non-raw memories from complete (macro-expanded) initializations.
291 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
292 // If our control input is a dead region, kill all below the region
293 Node *ctl = in(MemNode::Control);
294 if (ctl && remove_dead_region(phase, can_reshape))
295 return this;
296 ctl = in(MemNode::Control);
297 // Don't bother trying to transform a dead node
298 if (ctl && ctl->is_top()) return NodeSentinel;
299
300 PhaseIterGVN *igvn = phase->is_IterGVN();
301 // Wait if control on the worklist.
302 if (ctl && can_reshape && igvn != NULL) {
303 Node* bol = NULL;
304 Node* cmp = NULL;
305 if (ctl->in(0)->is_If()) {
306 assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity");
307 bol = ctl->in(0)->in(1);
308 if (bol->is_Bool())
309 cmp = ctl->in(0)->in(1)->in(1);
310 }
311 if (igvn->_worklist.member(ctl) ||
312 (bol != NULL && igvn->_worklist.member(bol)) ||
313 (cmp != NULL && igvn->_worklist.member(cmp)) ) {
314 // This control path may be dead.
315 // Delay this memory node transformation until the control is processed.
316 igvn->_worklist.push(this);
317 return NodeSentinel; // caller will return NULL
318 }
319 }
320 // Ignore if memory is dead, or self-loop
321 Node *mem = in(MemNode::Memory);
322 if (phase->type( mem ) == Type::TOP) return NodeSentinel; // caller will return NULL
323 assert(mem != this, "dead loop in MemNode::Ideal");
324
325 if (can_reshape && igvn != NULL && igvn->_worklist.member(mem)) {
326 // This memory slice may be dead.
327 // Delay this mem node transformation until the memory is processed.
328 igvn->_worklist.push(this);
329 return NodeSentinel; // caller will return NULL
330 }
331
332 Node *address = in(MemNode::Address);
333 const Type *t_adr = phase->type(address);
334 if (t_adr == Type::TOP) return NodeSentinel; // caller will return NULL
335
336 if (can_reshape && is_unsafe_access() && (t_adr == TypePtr::NULL_PTR)) {
337 // Unsafe off-heap access with zero address. Remove access and other control users
338 // to not confuse optimizations and add a HaltNode to fail if this is ever executed.
339 assert(ctl != NULL, "unsafe accesses should be control dependent");
340 for (DUIterator_Fast imax, i = ctl->fast_outs(imax); i < imax; i++) {
341 Node* u = ctl->fast_out(i);
342 if (u != ctl) {
343 igvn->rehash_node_delayed(u);
344 int nb = u->replace_edge(ctl, phase->C->top(), igvn);
345 --i, imax -= nb;
346 }
347 }
348 Node* frame = igvn->transform(new ParmNode(phase->C->start(), TypeFunc::FramePtr));
349 Node* halt = igvn->transform(new HaltNode(ctl, frame, "unsafe off-heap access with zero address"));
350 phase->C->root()->add_req(halt);
351 return this;
352 }
353
354 if (can_reshape && igvn != NULL &&
355 (igvn->_worklist.member(address) ||
356 (igvn->_worklist.size() > 0 && t_adr != adr_type())) ) {
357 // The address's base and type may change when the address is processed.
358 // Delay this mem node transformation until the address is processed.
359 igvn->_worklist.push(this);
360 return NodeSentinel; // caller will return NULL
361 }
362
363 // Do NOT remove or optimize the next lines: ensure a new alias index
364 // is allocated for an oop pointer type before Escape Analysis.
365 // Note: C++ will not remove it since the call has side effect.
366 if (t_adr->isa_oopptr()) {
367 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr());
368 }
369
370 Node* base = NULL;
371 if (address->is_AddP()) {
372 base = address->in(AddPNode::Base);
373 }
374 if (base != NULL && phase->type(base)->higher_equal(TypePtr::NULL_PTR) &&
375 !t_adr->isa_rawptr()) {
376 // Note: raw address has TOP base and top->higher_equal(TypePtr::NULL_PTR) is true.
377 // Skip this node optimization if its address has TOP base.
378 return NodeSentinel; // caller will return NULL
379 }
380
381 // Avoid independent memory operations
382 Node* old_mem = mem;
383
384 // The code which unhooks non-raw memories from complete (macro-expanded)
385 // initializations was removed. After macro-expansion all stores catched
386 // by Initialize node became raw stores and there is no information
387 // which memory slices they modify. So it is unsafe to move any memory
388 // operation above these stores. Also in most cases hooked non-raw memories
389 // were already unhooked by using information from detect_ptr_independence()
390 // and find_previous_store().
391
392 if (mem->is_MergeMem()) {
393 MergeMemNode* mmem = mem->as_MergeMem();
394 const TypePtr *tp = t_adr->is_ptr();
395
396 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
397 }
398
399 if (mem != old_mem) {
400 set_req(MemNode::Memory, mem);
401 if (can_reshape && old_mem->outcnt() == 0 && igvn != NULL) {
402 igvn->_worklist.push(old_mem);
403 }
404 if (phase->type(mem) == Type::TOP) return NodeSentinel;
405 return this;
406 }
407
408 // let the subclass continue analyzing...
409 return NULL;
410 }
411
412 // Helper function for proving some simple control dominations.
413 // Attempt to prove that all control inputs of 'dom' dominate 'sub'.
414 // Already assumes that 'dom' is available at 'sub', and that 'sub'
415 // is not a constant (dominated by the method's StartNode).
416 // Used by MemNode::find_previous_store to prove that the
417 // control input of a memory operation predates (dominates)
418 // an allocation it wants to look past.
419 bool MemNode::all_controls_dominate(Node* dom, Node* sub) {
420 if (dom == NULL || dom->is_top() || sub == NULL || sub->is_top())
421 return false; // Conservative answer for dead code
422
423 // Check 'dom'. Skip Proj and CatchProj nodes.
424 dom = dom->find_exact_control(dom);
425 if (dom == NULL || dom->is_top())
426 return false; // Conservative answer for dead code
427
428 if (dom == sub) {
429 // For the case when, for example, 'sub' is Initialize and the original
430 // 'dom' is Proj node of the 'sub'.
431 return false;
432 }
433
434 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub)
435 return true;
436
437 // 'dom' dominates 'sub' if its control edge and control edges
438 // of all its inputs dominate or equal to sub's control edge.
439
440 // Currently 'sub' is either Allocate, Initialize or Start nodes.
441 // Or Region for the check in LoadNode::Ideal();
442 // 'sub' should have sub->in(0) != NULL.
443 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() ||
444 sub->is_Region() || sub->is_Call(), "expecting only these nodes");
445
446 // Get control edge of 'sub'.
447 Node* orig_sub = sub;
448 sub = sub->find_exact_control(sub->in(0));
449 if (sub == NULL || sub->is_top())
450 return false; // Conservative answer for dead code
451
452 assert(sub->is_CFG(), "expecting control");
453
454 if (sub == dom)
455 return true;
456
457 if (sub->is_Start() || sub->is_Root())
458 return false;
459
460 {
461 // Check all control edges of 'dom'.
462
463 ResourceMark rm;
464 Node_List nlist;
465 Unique_Node_List dom_list;
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 ac that produces the memory state represented by parameter mem.
537 // Return ac if
538 // (a) can_see_stored_value=true and ac must have set the value for this load or if
539 // (b) can_see_stored_value=false and ac could have set the value for this load or if
540 // (c) can_see_stored_value=false and ac cannot have set the value for this load.
541 // In case (c) change the parameter mem to the memory input of ac to skip it
542 // when searching stored value.
543 // Otherwise return NULL.
544 Node* LoadNode::find_previous_arraycopy(PhaseTransform* phase, Node* ld_alloc, Node*& mem, bool can_see_stored_value) const {
545 ArrayCopyNode* ac = find_array_copy_clone(phase, ld_alloc, mem);
546 if (ac != NULL) {
547 Node* ld_addp = in(MemNode::Address);
548 Node* src = ac->in(ArrayCopyNode::Src);
549 const TypeAryPtr* ary_t = phase->type(src)->isa_aryptr();
550
551 // This is a load from a cloned array. The corresponding arraycopy ac must
552 // have set the value for the load and we can return ac but only if the load
553 // is known to be within bounds. This is checked below.
554 if (ary_t != NULL && ld_addp->is_AddP()) {
555 Node* ld_offs = ld_addp->in(AddPNode::Offset);
556 BasicType ary_elem = ary_t->klass()->as_array_klass()->element_type()->basic_type();
557 jlong header = arrayOopDesc::base_offset_in_bytes(ary_elem);
558 jlong elemsize = type2aelembytes(ary_elem);
559
560 const TypeX* ld_offs_t = phase->type(ld_offs)->isa_intptr_t();
561 const TypeInt* sizetype = ary_t->size();
562
563 if (ld_offs_t->_lo >= header && ld_offs_t->_hi < (sizetype->_lo * elemsize + header)) {
564 // The load is known to be within bounds. It receives its value from ac.
565 return ac;
566 }
567 // The load is known to be out-of-bounds.
568 }
569 // The load could be out-of-bounds. It must not be hoisted but must remain
570 // dependent on the runtime range check. This is achieved by returning NULL.
571 } else if (mem->is_Proj() && mem->in(0) != NULL && mem->in(0)->is_ArrayCopy()) {
572 ArrayCopyNode* ac = mem->in(0)->as_ArrayCopy();
573
574 if (ac->is_arraycopy_validated() ||
575 ac->is_copyof_validated() ||
576 ac->is_copyofrange_validated()) {
577 Node* ld_addp = in(MemNode::Address);
578 if (ld_addp->is_AddP()) {
579 Node* ld_base = ld_addp->in(AddPNode::Address);
580 Node* ld_offs = ld_addp->in(AddPNode::Offset);
581
582 Node* dest = ac->in(ArrayCopyNode::Dest);
583
584 if (dest == ld_base) {
585 const TypeX *ld_offs_t = phase->type(ld_offs)->isa_intptr_t();
586 if (ac->modifies(ld_offs_t->_lo, ld_offs_t->_hi, phase, can_see_stored_value)) {
587 return ac;
588 }
589 if (!can_see_stored_value) {
590 mem = ac->in(TypeFunc::Memory);
591 return ac;
592 }
593 }
594 }
595 }
596 }
597 return NULL;
598 }
599
600 ArrayCopyNode* MemNode::find_array_copy_clone(PhaseTransform* phase, Node* ld_alloc, Node* mem) const {
601 if (mem->is_Proj() && mem->in(0) != NULL && (mem->in(0)->Opcode() == Op_MemBarStoreStore ||
602 mem->in(0)->Opcode() == Op_MemBarCPUOrder)) {
603 if (ld_alloc != NULL) {
604 // Check if there is an array copy for a clone
605 Node* mb = mem->in(0);
606 ArrayCopyNode* ac = NULL;
607 if (mb->in(0) != NULL && mb->in(0)->is_Proj() &&
608 mb->in(0)->in(0) != NULL && mb->in(0)->in(0)->is_ArrayCopy()) {
609 ac = mb->in(0)->in(0)->as_ArrayCopy();
610 } else {
611 // Step over GC barrier when ReduceInitialCardMarks is disabled
612 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
613 Node* control_proj_ac = bs->step_over_gc_barrier(mb->in(0));
614
615 if (control_proj_ac->is_Proj() && control_proj_ac->in(0)->is_ArrayCopy()) {
616 ac = control_proj_ac->in(0)->as_ArrayCopy();
617 }
618 }
619
620 if (ac != NULL && ac->is_clonebasic()) {
621 AllocateNode* alloc = AllocateNode::Ideal_allocation(ac->in(ArrayCopyNode::Dest), phase);
622 if (alloc != NULL && alloc == ld_alloc) {
623 return ac;
624 }
625 }
626 }
627 }
628 return NULL;
629 }
630
631 // The logic for reordering loads and stores uses four steps:
632 // (a) Walk carefully past stores and initializations which we
633 // can prove are independent of this load.
634 // (b) Observe that the next memory state makes an exact match
635 // with self (load or store), and locate the relevant store.
636 // (c) Ensure that, if we were to wire self directly to the store,
637 // the optimizer would fold it up somehow.
638 // (d) Do the rewiring, and return, depending on some other part of
639 // the optimizer to fold up the load.
640 // This routine handles steps (a) and (b). Steps (c) and (d) are
641 // specific to loads and stores, so they are handled by the callers.
642 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.)
643 //
644 Node* MemNode::find_previous_store(PhaseTransform* phase) {
645 Node* ctrl = in(MemNode::Control);
646 Node* adr = in(MemNode::Address);
647 intptr_t offset = 0;
648 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
649 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase);
650
651 if (offset == Type::OffsetBot)
652 return NULL; // cannot unalias unless there are precise offsets
653
654 const bool adr_maybe_raw = check_if_adr_maybe_raw(adr);
655 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr();
656
657 intptr_t size_in_bytes = memory_size();
658
659 Node* mem = in(MemNode::Memory); // start searching here...
660
661 int cnt = 50; // Cycle limiter
662 for (;;) { // While we can dance past unrelated stores...
663 if (--cnt < 0) break; // Caught in cycle or a complicated dance?
664
665 Node* prev = mem;
666 if (mem->is_Store()) {
667 Node* st_adr = mem->in(MemNode::Address);
668 intptr_t st_offset = 0;
669 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
670 if (st_base == NULL)
671 break; // inscrutable pointer
672
673 // For raw accesses it's not enough to prove that constant offsets don't intersect.
674 // We need the bases to be the equal in order for the offset check to make sense.
675 if ((adr_maybe_raw || check_if_adr_maybe_raw(st_adr)) && st_base != base) {
676 break;
677 }
678
679 if (st_offset != offset && st_offset != Type::OffsetBot) {
680 const int MAX_STORE = MAX2(BytesPerLong, (int)MaxVectorSize);
681 assert(mem->as_Store()->memory_size() <= MAX_STORE, "");
682 if (st_offset >= offset + size_in_bytes ||
683 st_offset <= offset - MAX_STORE ||
684 st_offset <= offset - mem->as_Store()->memory_size()) {
685 // Success: The offsets are provably independent.
686 // (You may ask, why not just test st_offset != offset and be done?
687 // The answer is that stores of different sizes can co-exist
688 // in the same sequence of RawMem effects. We sometimes initialize
689 // a whole 'tile' of array elements with a single jint or jlong.)
690 mem = mem->in(MemNode::Memory);
691 continue; // (a) advance through independent store memory
692 }
693 }
694 if (st_base != base &&
695 detect_ptr_independence(base, alloc,
696 st_base,
697 AllocateNode::Ideal_allocation(st_base, phase),
698 phase)) {
699 // Success: The bases are provably independent.
700 mem = mem->in(MemNode::Memory);
701 continue; // (a) advance through independent store memory
702 }
703
704 // (b) At this point, if the bases or offsets do not agree, we lose,
705 // since we have not managed to prove 'this' and 'mem' independent.
706 if (st_base == base && st_offset == offset) {
707 return mem; // let caller handle steps (c), (d)
708 }
709
710 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
711 InitializeNode* st_init = mem->in(0)->as_Initialize();
712 AllocateNode* st_alloc = st_init->allocation();
713 if (st_alloc == NULL)
714 break; // something degenerated
715 bool known_identical = false;
716 bool known_independent = false;
717 if (alloc == st_alloc)
718 known_identical = true;
719 else if (alloc != NULL)
720 known_independent = true;
721 else if (all_controls_dominate(this, st_alloc))
722 known_independent = true;
723
724 if (known_independent) {
725 // The bases are provably independent: Either they are
726 // manifestly distinct allocations, or else the control
727 // of this load dominates the store's allocation.
728 int alias_idx = phase->C->get_alias_index(adr_type());
729 if (alias_idx == Compile::AliasIdxRaw) {
730 mem = st_alloc->in(TypeFunc::Memory);
731 } else {
732 mem = st_init->memory(alias_idx);
733 }
734 continue; // (a) advance through independent store memory
735 }
736
737 // (b) at this point, if we are not looking at a store initializing
738 // the same allocation we are loading from, we lose.
739 if (known_identical) {
740 // From caller, can_see_stored_value will consult find_captured_store.
741 return mem; // let caller handle steps (c), (d)
742 }
743
744 } else if (find_previous_arraycopy(phase, alloc, mem, false) != NULL) {
745 if (prev != mem) {
746 // Found an arraycopy but it doesn't affect that load
747 continue;
748 }
749 // Found an arraycopy that may affect that load
750 return mem;
751 } else if (addr_t != NULL && addr_t->is_known_instance_field()) {
752 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
753 if (mem->is_Proj() && mem->in(0)->is_Call()) {
754 // ArrayCopyNodes processed here as well.
755 CallNode *call = mem->in(0)->as_Call();
756 if (!call->may_modify(addr_t, phase)) {
757 mem = call->in(TypeFunc::Memory);
758 continue; // (a) advance through independent call memory
759 }
760 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) {
761 ArrayCopyNode* ac = NULL;
762 if (ArrayCopyNode::may_modify(addr_t, mem->in(0)->as_MemBar(), phase, ac)) {
763 break;
764 }
765 mem = mem->in(0)->in(TypeFunc::Memory);
766 continue; // (a) advance through independent MemBar memory
767 } else if (mem->is_ClearArray()) {
768 if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) {
769 // (the call updated 'mem' value)
770 continue; // (a) advance through independent allocation memory
771 } else {
772 // Can not bypass initialization of the instance
773 // we are looking for.
774 return mem;
775 }
776 } else if (mem->is_MergeMem()) {
777 int alias_idx = phase->C->get_alias_index(adr_type());
778 mem = mem->as_MergeMem()->memory_at(alias_idx);
779 continue; // (a) advance through independent MergeMem memory
780 }
781 }
782
783 // Unless there is an explicit 'continue', we must bail out here,
784 // because 'mem' is an inscrutable memory state (e.g., a call).
785 break;
786 }
787
788 return NULL; // bail out
789 }
790
791 //----------------------calculate_adr_type-------------------------------------
792 // Helper function. Notices when the given type of address hits top or bottom.
793 // Also, asserts a cross-check of the type against the expected address type.
794 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
795 if (t == Type::TOP) return NULL; // does not touch memory any more?
796 #ifdef ASSERT
797 if (!VerifyAliases || VMError::is_error_reported() || Node::in_dump()) cross_check = NULL;
798 #endif
799 const TypePtr* tp = t->isa_ptr();
800 if (tp == NULL) {
801 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
802 return TypePtr::BOTTOM; // touches lots of memory
803 } else {
804 #ifdef ASSERT
805 // %%%% [phh] We don't check the alias index if cross_check is
806 // TypeRawPtr::BOTTOM. Needs to be investigated.
807 if (cross_check != NULL &&
808 cross_check != TypePtr::BOTTOM &&
809 cross_check != TypeRawPtr::BOTTOM) {
810 // Recheck the alias index, to see if it has changed (due to a bug).
811 Compile* C = Compile::current();
812 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
813 "must stay in the original alias category");
814 // The type of the address must be contained in the adr_type,
815 // disregarding "null"-ness.
816 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
817 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
818 assert(cross_check->meet(tp_notnull) == cross_check->remove_speculative(),
819 "real address must not escape from expected memory type");
820 }
821 #endif
822 return tp;
823 }
824 }
825
826 //=============================================================================
827 // Should LoadNode::Ideal() attempt to remove control edges?
828 bool LoadNode::can_remove_control() const {
829 return true;
830 }
831 uint LoadNode::size_of() const { return sizeof(*this); }
832 bool LoadNode::cmp( const Node &n ) const
833 { return !Type::cmp( _type, ((LoadNode&)n)._type ); }
834 const Type *LoadNode::bottom_type() const { return _type; }
835 uint LoadNode::ideal_reg() const {
836 return _type->ideal_reg();
837 }
838
839 #ifndef PRODUCT
840 void LoadNode::dump_spec(outputStream *st) const {
841 MemNode::dump_spec(st);
842 if( !Verbose && !WizardMode ) {
843 // standard dump does this in Verbose and WizardMode
844 st->print(" #"); _type->dump_on(st);
845 }
846 if (!depends_only_on_test()) {
847 st->print(" (does not depend only on test)");
848 }
849 }
850 #endif
851
852 #ifdef ASSERT
853 //----------------------------is_immutable_value-------------------------------
854 // Helper function to allow a raw load without control edge for some cases
855 bool LoadNode::is_immutable_value(Node* adr) {
856 return (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() &&
857 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal &&
858 (adr->in(AddPNode::Offset)->find_intptr_t_con(-1) ==
859 in_bytes(JavaThread::osthread_offset()) ||
860 adr->in(AddPNode::Offset)->find_intptr_t_con(-1) ==
861 in_bytes(JavaThread::threadObj_offset())));
862 }
863 #endif
864
865 //----------------------------LoadNode::make-----------------------------------
866 // Polymorphic factory method:
867 Node *LoadNode::make(PhaseGVN& gvn, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt, MemOrd mo,
868 ControlDependency control_dependency, bool unaligned, bool mismatched, bool unsafe, uint8_t barrier_data) {
869 Compile* C = gvn.C;
870
871 // sanity check the alias category against the created node type
872 assert(!(adr_type->isa_oopptr() &&
873 adr_type->offset() == oopDesc::klass_offset_in_bytes()),
874 "use LoadKlassNode instead");
875 assert(!(adr_type->isa_aryptr() &&
876 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
877 "use LoadRangeNode instead");
878 // Check control edge of raw loads
879 assert( ctl != NULL || C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
880 // oop will be recorded in oop map if load crosses safepoint
881 rt->isa_oopptr() || is_immutable_value(adr),
882 "raw memory operations should have control edge");
883 LoadNode* load = NULL;
884 switch (bt) {
885 case T_BOOLEAN: load = new LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
886 case T_BYTE: load = new LoadBNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
887 case T_INT: load = new LoadINode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
888 case T_CHAR: load = new LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
889 case T_SHORT: load = new LoadSNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
890 case T_LONG: load = new LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency); break;
891 case T_FLOAT: load = new LoadFNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); break;
892 case T_DOUBLE: load = new LoadDNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); break;
893 case T_ADDRESS: load = new LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency); break;
894 case T_INLINE_TYPE:
895 case T_OBJECT:
896 #ifdef _LP64
897 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
898 load = new LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo, control_dependency);
899 } else
900 #endif
901 {
902 assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop");
903 load = new LoadPNode(ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency);
904 }
905 break;
906 default:
907 ShouldNotReachHere();
908 break;
909 }
910 assert(load != NULL, "LoadNode should have been created");
911 if (unaligned) {
912 load->set_unaligned_access();
913 }
914 if (mismatched) {
915 load->set_mismatched_access();
916 }
917 if (unsafe) {
918 load->set_unsafe_access();
919 }
920 load->set_barrier_data(barrier_data);
921 if (load->Opcode() == Op_LoadN) {
922 Node* ld = gvn.transform(load);
923 return new DecodeNNode(ld, ld->bottom_type()->make_ptr());
924 }
925
926 return load;
927 }
928
929 LoadLNode* LoadLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo,
930 ControlDependency control_dependency, bool unaligned, bool mismatched, bool unsafe, uint8_t barrier_data) {
931 bool require_atomic = true;
932 LoadLNode* load = new LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency, require_atomic);
933 if (unaligned) {
934 load->set_unaligned_access();
935 }
936 if (mismatched) {
937 load->set_mismatched_access();
938 }
939 if (unsafe) {
940 load->set_unsafe_access();
941 }
942 load->set_barrier_data(barrier_data);
943 return load;
944 }
945
946 LoadDNode* LoadDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo,
947 ControlDependency control_dependency, bool unaligned, bool mismatched, bool unsafe, uint8_t barrier_data) {
948 bool require_atomic = true;
949 LoadDNode* load = new LoadDNode(ctl, mem, adr, adr_type, rt, mo, control_dependency, require_atomic);
950 if (unaligned) {
951 load->set_unaligned_access();
952 }
953 if (mismatched) {
954 load->set_mismatched_access();
955 }
956 if (unsafe) {
957 load->set_unsafe_access();
958 }
959 load->set_barrier_data(barrier_data);
960 return load;
961 }
962
963
964
965 //------------------------------hash-------------------------------------------
966 uint LoadNode::hash() const {
967 // unroll addition of interesting fields
968 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
969 }
970
971 static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) {
972 if ((atp != NULL) && (atp->index() >= Compile::AliasIdxRaw)) {
973 bool non_volatile = (atp->field() != NULL) && !atp->field()->is_volatile();
974 bool is_stable_ary = FoldStableValues &&
975 (tp != NULL) && (tp->isa_aryptr() != NULL) &&
976 tp->isa_aryptr()->is_stable();
977
978 return (eliminate_boxing && non_volatile) || is_stable_ary;
979 }
980
981 return false;
982 }
983
984 // Is the value loaded previously stored by an arraycopy? If so return
985 // a load node that reads from the source array so we may be able to
986 // optimize out the ArrayCopy node later.
987 Node* LoadNode::can_see_arraycopy_value(Node* st, PhaseGVN* phase) const {
988 Node* ld_adr = in(MemNode::Address);
989 intptr_t ld_off = 0;
990 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
991 Node* ac = find_previous_arraycopy(phase, ld_alloc, st, true);
992 if (ac != NULL) {
993 assert(ac->is_ArrayCopy(), "what kind of node can this be?");
994
995 Node* mem = ac->in(TypeFunc::Memory);
996 Node* ctl = ac->in(0);
997 Node* src = ac->in(ArrayCopyNode::Src);
998
999 if (!ac->as_ArrayCopy()->is_clonebasic() && !phase->type(src)->isa_aryptr()) {
1000 return NULL;
1001 }
1002
1003 LoadNode* ld = clone()->as_Load();
1004 Node* addp = in(MemNode::Address)->clone();
1005 if (ac->as_ArrayCopy()->is_clonebasic()) {
1006 assert(ld_alloc != NULL, "need an alloc");
1007 assert(addp->is_AddP(), "address must be addp");
1008 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1009 assert(bs->step_over_gc_barrier(addp->in(AddPNode::Base)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)), "strange pattern");
1010 assert(bs->step_over_gc_barrier(addp->in(AddPNode::Address)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)), "strange pattern");
1011 addp->set_req(AddPNode::Base, src);
1012 addp->set_req(AddPNode::Address, src);
1013 } else {
1014 assert(ac->as_ArrayCopy()->is_arraycopy_validated() ||
1015 ac->as_ArrayCopy()->is_copyof_validated() ||
1016 ac->as_ArrayCopy()->is_copyofrange_validated(), "only supported cases");
1017 assert(addp->in(AddPNode::Base) == addp->in(AddPNode::Address), "should be");
1018 addp->set_req(AddPNode::Base, src);
1019 addp->set_req(AddPNode::Address, src);
1020
1021 const TypeAryPtr* ary_t = phase->type(in(MemNode::Address))->isa_aryptr();
1022 BasicType ary_elem = ary_t->klass()->as_array_klass()->element_type()->basic_type();
1023 uint header = arrayOopDesc::base_offset_in_bytes(ary_elem);
1024 uint shift = exact_log2(type2aelembytes(ary_elem));
1025 if (ary_t->klass()->is_flat_array_klass()) {
1026 ciFlatArrayKlass* vak = ary_t->klass()->as_flat_array_klass();
1027 shift = vak->log2_element_size();
1028 }
1029
1030 Node* diff = phase->transform(new SubINode(ac->in(ArrayCopyNode::SrcPos), ac->in(ArrayCopyNode::DestPos)));
1031 #ifdef _LP64
1032 diff = phase->transform(new ConvI2LNode(diff));
1033 #endif
1034 diff = phase->transform(new LShiftXNode(diff, phase->intcon(shift)));
1035
1036 Node* offset = phase->transform(new AddXNode(addp->in(AddPNode::Offset), diff));
1037 addp->set_req(AddPNode::Offset, offset);
1038 }
1039 addp = phase->transform(addp);
1040 #ifdef ASSERT
1041 const TypePtr* adr_type = phase->type(addp)->is_ptr();
1042 ld->_adr_type = adr_type;
1043 #endif
1044 ld->set_req(MemNode::Address, addp);
1045 ld->set_req(0, ctl);
1046 ld->set_req(MemNode::Memory, mem);
1047 // load depends on the tests that validate the arraycopy
1048 ld->_control_dependency = UnknownControl;
1049 return ld;
1050 }
1051 return NULL;
1052 }
1053
1054
1055 //---------------------------can_see_stored_value------------------------------
1056 // This routine exists to make sure this set of tests is done the same
1057 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
1058 // will change the graph shape in a way which makes memory alive twice at the
1059 // same time (uses the Oracle model of aliasing), then some
1060 // LoadXNode::Identity will fold things back to the equivalence-class model
1061 // of aliasing.
1062 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const {
1063 Node* ld_adr = in(MemNode::Address);
1064 intptr_t ld_off = 0;
1065 Node* ld_base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ld_off);
1066 Node* ld_alloc = AllocateNode::Ideal_allocation(ld_base, phase);
1067 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
1068 Compile::AliasType* atp = (tp != NULL) ? phase->C->alias_type(tp) : NULL;
1069 // This is more general than load from boxing objects.
1070 if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) {
1071 uint alias_idx = atp->index();
1072 Node* result = NULL;
1073 Node* current = st;
1074 // Skip through chains of MemBarNodes checking the MergeMems for
1075 // new states for the slice of this load. Stop once any other
1076 // kind of node is encountered. Loads from final memory can skip
1077 // through any kind of MemBar but normal loads shouldn't skip
1078 // through MemBarAcquire since the could allow them to move out of
1079 // a synchronized region. It is not safe to step over MemBarCPUOrder,
1080 // because alias info above them may be inaccurate (e.g., due to
1081 // mixed/mismatched unsafe accesses).
1082 bool is_final_mem = !atp->is_rewritable();
1083 while (current->is_Proj()) {
1084 int opc = current->in(0)->Opcode();
1085 if ((is_final_mem && (opc == Op_MemBarAcquire ||
1086 opc == Op_MemBarAcquireLock ||
1087 opc == Op_LoadFence)) ||
1088 opc == Op_MemBarRelease ||
1089 opc == Op_StoreFence ||
1090 opc == Op_MemBarReleaseLock ||
1091 opc == Op_MemBarStoreStore) {
1092 Node* mem = current->in(0)->in(TypeFunc::Memory);
1093 if (mem->is_MergeMem()) {
1094 MergeMemNode* merge = mem->as_MergeMem();
1095 Node* new_st = merge->memory_at(alias_idx);
1096 if (new_st == merge->base_memory()) {
1097 // Keep searching
1098 current = new_st;
1099 continue;
1100 }
1101 // Save the new memory state for the slice and fall through
1102 // to exit.
1103 result = new_st;
1104 }
1105 }
1106 break;
1107 }
1108 if (result != NULL) {
1109 st = result;
1110 }
1111 }
1112
1113 // Loop around twice in the case Load -> Initialize -> Store.
1114 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
1115 for (int trip = 0; trip <= 1; trip++) {
1116
1117 if (st->is_Store()) {
1118 Node* st_adr = st->in(MemNode::Address);
1119 if (st_adr != ld_adr) {
1120 // Try harder before giving up. Unify base pointers with casts (e.g., raw/non-raw pointers).
1121 intptr_t st_off = 0;
1122 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_off);
1123 if (ld_base == NULL) return NULL;
1124 if (st_base == NULL) return NULL;
1125 if (!ld_base->eqv_uncast(st_base, /*keep_deps=*/true)) return NULL;
1126 if (ld_off != st_off) return NULL;
1127 if (ld_off == Type::OffsetBot) return NULL;
1128 // Same base, same offset.
1129 // Possible improvement for arrays: check index value instead of absolute offset.
1130
1131 // At this point we have proven something like this setup:
1132 // B = << base >>
1133 // L = LoadQ(AddP(Check/CastPP(B), #Off))
1134 // S = StoreQ(AddP( B , #Off), V)
1135 // (Actually, we haven't yet proven the Q's are the same.)
1136 // In other words, we are loading from a casted version of
1137 // the same pointer-and-offset that we stored to.
1138 // Casted version may carry a dependency and it is respected.
1139 // Thus, we are able to replace L by V.
1140 }
1141 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
1142 if (store_Opcode() != st->Opcode()) {
1143 return NULL;
1144 }
1145 // LoadVector/StoreVector needs additional check to ensure the types match.
1146 if (store_Opcode() == Op_StoreVector) {
1147 const TypeVect* in_vt = st->as_StoreVector()->vect_type();
1148 const TypeVect* out_vt = is_Load() ? as_LoadVector()->vect_type() : as_StoreVector()->vect_type();
1149 if (in_vt != out_vt) {
1150 return NULL;
1151 }
1152 }
1153 return st->in(MemNode::ValueIn);
1154 }
1155
1156 // A load from a freshly-created object always returns zero.
1157 // (This can happen after LoadNode::Ideal resets the load's memory input
1158 // to find_captured_store, which returned InitializeNode::zero_memory.)
1159 if (st->is_Proj() && st->in(0)->is_Allocate() &&
1160 (st->in(0) == ld_alloc) &&
1161 (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) {
1162 // return a zero value for the load's basic type
1163 // (This is one of the few places where a generic PhaseTransform
1164 // can create new nodes. Think of it as lazily manifesting
1165 // virtually pre-existing constants.)
1166 assert(memory_type() != T_INLINE_TYPE, "should not be used for inline types");
1167 Node* default_value = ld_alloc->in(AllocateNode::DefaultValue);
1168 if (default_value != NULL) {
1169 return default_value;
1170 }
1171 assert(ld_alloc->in(AllocateNode::RawDefaultValue) == NULL, "default value may not be null");
1172 if (memory_type() != T_VOID) {
1173 if (ReduceBulkZeroing || find_array_copy_clone(phase, ld_alloc, in(MemNode::Memory)) == NULL) {
1174 // If ReduceBulkZeroing is disabled, we need to check if the allocation does not belong to an
1175 // ArrayCopyNode clone. If it does, then we cannot assume zero since the initialization is done
1176 // by the ArrayCopyNode.
1177 return phase->zerocon(memory_type());
1178 }
1179 } else {
1180 // TODO: materialize all-zero vector constant
1181 assert(!isa_Load() || as_Load()->type()->isa_vect(), "");
1182 }
1183 }
1184
1185 // A load from an initialization barrier can match a captured store.
1186 if (st->is_Proj() && st->in(0)->is_Initialize()) {
1187 InitializeNode* init = st->in(0)->as_Initialize();
1188 AllocateNode* alloc = init->allocation();
1189 if ((alloc != NULL) && (alloc == ld_alloc)) {
1190 // examine a captured store value
1191 st = init->find_captured_store(ld_off, memory_size(), phase);
1192 if (st != NULL) {
1193 continue; // take one more trip around
1194 }
1195 }
1196 }
1197
1198 // Load boxed value from result of valueOf() call is input parameter.
1199 if (this->is_Load() && ld_adr->is_AddP() &&
1200 (tp != NULL) && tp->is_ptr_to_boxed_value()) {
1201 intptr_t ignore = 0;
1202 Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore);
1203 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1204 base = bs->step_over_gc_barrier(base);
1205 if (base != NULL && base->is_Proj() &&
1206 base->as_Proj()->_con == TypeFunc::Parms &&
1207 base->in(0)->is_CallStaticJava() &&
1208 base->in(0)->as_CallStaticJava()->is_boxing_method()) {
1209 return base->in(0)->in(TypeFunc::Parms);
1210 }
1211 }
1212
1213 break;
1214 }
1215
1216 return NULL;
1217 }
1218
1219 //----------------------is_instance_field_load_with_local_phi------------------
1220 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
1221 if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl &&
1222 in(Address)->is_AddP() ) {
1223 const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr();
1224 // Only instances and boxed values.
1225 if( t_oop != NULL &&
1226 (t_oop->is_ptr_to_boxed_value() ||
1227 t_oop->is_known_instance_field()) &&
1228 t_oop->offset() != Type::OffsetBot &&
1229 t_oop->offset() != Type::OffsetTop) {
1230 return true;
1231 }
1232 }
1233 return false;
1234 }
1235
1236 //------------------------------Identity---------------------------------------
1237 // Loads are identity if previous store is to same address
1238 Node* LoadNode::Identity(PhaseGVN* phase) {
1239 // Loading from an InlineTypePtr? The InlineTypePtr has the values of
1240 // all fields as input. Look for the field with matching offset.
1241 Node* addr = in(Address);
1242 intptr_t offset;
1243 Node* base = AddPNode::Ideal_base_and_offset(addr, phase, offset);
1244 if (base != NULL && base->is_InlineTypePtr() && offset > oopDesc::klass_offset_in_bytes()) {
1245 Node* value = base->as_InlineTypePtr()->field_value_by_offset((int)offset, true);
1246 if (value->is_InlineType()) {
1247 // Non-flattened inline type field
1248 InlineTypeNode* vt = value->as_InlineType();
1249 if (vt->is_allocated(phase)) {
1250 value = vt->get_oop();
1251 } else {
1252 // Not yet allocated, bail out
1253 value = NULL;
1254 }
1255 }
1256 if (value != NULL) {
1257 if (Opcode() == Op_LoadN) {
1258 // Encode oop value if we are loading a narrow oop
1259 assert(!phase->type(value)->isa_narrowoop(), "should already be decoded");
1260 value = phase->transform(new EncodePNode(value, bottom_type()));
1261 }
1262 return value;
1263 }
1264 }
1265
1266 // If the previous store-maker is the right kind of Store, and the store is
1267 // to the same address, then we are equal to the value stored.
1268 Node* mem = in(Memory);
1269 Node* value = can_see_stored_value(mem, phase);
1270 if( value ) {
1271 // byte, short & char stores truncate naturally.
1272 // A load has to load the truncated value which requires
1273 // some sort of masking operation and that requires an
1274 // Ideal call instead of an Identity call.
1275 if (memory_size() < BytesPerInt) {
1276 // If the input to the store does not fit with the load's result type,
1277 // it must be truncated via an Ideal call.
1278 if (!phase->type(value)->higher_equal(phase->type(this)))
1279 return this;
1280 }
1281 // (This works even when value is a Con, but LoadNode::Value
1282 // usually runs first, producing the singleton type of the Con.)
1283 return value;
1284 }
1285
1286 // Search for an existing data phi which was generated before for the same
1287 // instance's field to avoid infinite generation of phis in a loop.
1288 Node *region = mem->in(0);
1289 if (is_instance_field_load_with_local_phi(region)) {
1290 const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr();
1291 int this_index = phase->C->get_alias_index(addr_t);
1292 int this_offset = addr_t->offset();
1293 int this_iid = addr_t->instance_id();
1294 if (!addr_t->is_known_instance() &&
1295 addr_t->is_ptr_to_boxed_value()) {
1296 // Use _idx of address base (could be Phi node) for boxed values.
1297 intptr_t ignore = 0;
1298 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1299 if (base == NULL) {
1300 return this;
1301 }
1302 this_iid = base->_idx;
1303 }
1304 const Type* this_type = bottom_type();
1305 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1306 Node* phi = region->fast_out(i);
1307 if (phi->is_Phi() && phi != mem &&
1308 phi->as_Phi()->is_same_inst_field(this_type, (int)mem->_idx, this_iid, this_index, this_offset)) {
1309 return phi;
1310 }
1311 }
1312 }
1313
1314 return this;
1315 }
1316
1317 // Construct an equivalent unsigned load.
1318 Node* LoadNode::convert_to_unsigned_load(PhaseGVN& gvn) {
1319 BasicType bt = T_ILLEGAL;
1320 const Type* rt = NULL;
1321 switch (Opcode()) {
1322 case Op_LoadUB: return this;
1323 case Op_LoadUS: return this;
1324 case Op_LoadB: bt = T_BOOLEAN; rt = TypeInt::UBYTE; break;
1325 case Op_LoadS: bt = T_CHAR; rt = TypeInt::CHAR; break;
1326 default:
1327 assert(false, "no unsigned variant: %s", Name());
1328 return NULL;
1329 }
1330 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1331 raw_adr_type(), rt, bt, _mo, _control_dependency,
1332 is_unaligned_access(), is_mismatched_access());
1333 }
1334
1335 // Construct an equivalent signed load.
1336 Node* LoadNode::convert_to_signed_load(PhaseGVN& gvn) {
1337 BasicType bt = T_ILLEGAL;
1338 const Type* rt = NULL;
1339 switch (Opcode()) {
1340 case Op_LoadUB: bt = T_BYTE; rt = TypeInt::BYTE; break;
1341 case Op_LoadUS: bt = T_SHORT; rt = TypeInt::SHORT; break;
1342 case Op_LoadB: // fall through
1343 case Op_LoadS: // fall through
1344 case Op_LoadI: // fall through
1345 case Op_LoadL: return this;
1346 default:
1347 assert(false, "no signed variant: %s", Name());
1348 return NULL;
1349 }
1350 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1351 raw_adr_type(), rt, bt, _mo, _control_dependency,
1352 is_unaligned_access(), is_mismatched_access());
1353 }
1354
1355 bool LoadNode::has_reinterpret_variant(const Type* rt) {
1356 BasicType bt = rt->basic_type();
1357 switch (Opcode()) {
1358 case Op_LoadI: return (bt == T_FLOAT);
1359 case Op_LoadL: return (bt == T_DOUBLE);
1360 case Op_LoadF: return (bt == T_INT);
1361 case Op_LoadD: return (bt == T_LONG);
1362
1363 default: return false;
1364 }
1365 }
1366
1367 Node* LoadNode::convert_to_reinterpret_load(PhaseGVN& gvn, const Type* rt) {
1368 BasicType bt = rt->basic_type();
1369 assert(has_reinterpret_variant(rt), "no reinterpret variant: %s %s", Name(), type2name(bt));
1370 bool is_mismatched = is_mismatched_access();
1371 const TypeRawPtr* raw_type = gvn.type(in(MemNode::Memory))->isa_rawptr();
1372 if (raw_type == NULL) {
1373 is_mismatched = true; // conservatively match all non-raw accesses as mismatched
1374 }
1375 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1376 raw_adr_type(), rt, bt, _mo, _control_dependency,
1377 is_unaligned_access(), is_mismatched);
1378 }
1379
1380 bool StoreNode::has_reinterpret_variant(const Type* vt) {
1381 BasicType bt = vt->basic_type();
1382 switch (Opcode()) {
1383 case Op_StoreI: return (bt == T_FLOAT);
1384 case Op_StoreL: return (bt == T_DOUBLE);
1385 case Op_StoreF: return (bt == T_INT);
1386 case Op_StoreD: return (bt == T_LONG);
1387
1388 default: return false;
1389 }
1390 }
1391
1392 Node* StoreNode::convert_to_reinterpret_store(PhaseGVN& gvn, Node* val, const Type* vt) {
1393 BasicType bt = vt->basic_type();
1394 assert(has_reinterpret_variant(vt), "no reinterpret variant: %s %s", Name(), type2name(bt));
1395 StoreNode* st = StoreNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address), raw_adr_type(), val, bt, _mo);
1396
1397 bool is_mismatched = is_mismatched_access();
1398 const TypeRawPtr* raw_type = gvn.type(in(MemNode::Memory))->isa_rawptr();
1399 if (raw_type == NULL) {
1400 is_mismatched = true; // conservatively match all non-raw accesses as mismatched
1401 }
1402 if (is_mismatched) {
1403 st->set_mismatched_access();
1404 }
1405 return st;
1406 }
1407
1408 // We're loading from an object which has autobox behaviour.
1409 // If this object is result of a valueOf call we'll have a phi
1410 // merging a newly allocated object and a load from the cache.
1411 // We want to replace this load with the original incoming
1412 // argument to the valueOf call.
1413 Node* LoadNode::eliminate_autobox(PhaseIterGVN* igvn) {
1414 assert(igvn->C->eliminate_boxing(), "sanity");
1415 intptr_t ignore = 0;
1416 Node* base = AddPNode::Ideal_base_and_offset(in(Address), igvn, ignore);
1417 if ((base == NULL) || base->is_Phi()) {
1418 // Push the loads from the phi that comes from valueOf up
1419 // through it to allow elimination of the loads and the recovery
1420 // of the original value. It is done in split_through_phi().
1421 return NULL;
1422 } else if (base->is_Load() ||
1423 (base->is_DecodeN() && base->in(1)->is_Load())) {
1424 // Eliminate the load of boxed value for integer types from the cache
1425 // array by deriving the value from the index into the array.
1426 // Capture the offset of the load and then reverse the computation.
1427
1428 // Get LoadN node which loads a boxing object from 'cache' array.
1429 if (base->is_DecodeN()) {
1430 base = base->in(1);
1431 }
1432 if (!base->in(Address)->is_AddP()) {
1433 return NULL; // Complex address
1434 }
1435 AddPNode* address = base->in(Address)->as_AddP();
1436 Node* cache_base = address->in(AddPNode::Base);
1437 if ((cache_base != NULL) && cache_base->is_DecodeN()) {
1438 // Get ConP node which is static 'cache' field.
1439 cache_base = cache_base->in(1);
1440 }
1441 if ((cache_base != NULL) && cache_base->is_Con()) {
1442 const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr();
1443 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1444 Node* elements[4];
1445 int shift = exact_log2(type2aelembytes(T_OBJECT));
1446 int count = address->unpack_offsets(elements, ARRAY_SIZE(elements));
1447 if (count > 0 && elements[0]->is_Con() &&
1448 (count == 1 ||
1449 (count == 2 && elements[1]->Opcode() == Op_LShiftX &&
1450 elements[1]->in(2) == igvn->intcon(shift)))) {
1451 ciObjArray* array = base_type->const_oop()->as_obj_array();
1452 // Fetch the box object cache[0] at the base of the array and get its value
1453 ciInstance* box = array->obj_at(0)->as_instance();
1454 ciInstanceKlass* ik = box->klass()->as_instance_klass();
1455 assert(ik->is_box_klass(), "sanity");
1456 assert(ik->nof_nonstatic_fields() == 1, "change following code");
1457 if (ik->nof_nonstatic_fields() == 1) {
1458 // This should be true nonstatic_field_at requires calling
1459 // nof_nonstatic_fields so check it anyway
1460 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1461 BasicType bt = c.basic_type();
1462 // Only integer types have boxing cache.
1463 assert(bt == T_BOOLEAN || bt == T_CHAR ||
1464 bt == T_BYTE || bt == T_SHORT ||
1465 bt == T_INT || bt == T_LONG, "wrong type = %s", type2name(bt));
1466 jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int();
1467 if (cache_low != (int)cache_low) {
1468 return NULL; // should not happen since cache is array indexed by value
1469 }
1470 jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift);
1471 if (offset != (int)offset) {
1472 return NULL; // should not happen since cache is array indexed by value
1473 }
1474 // Add up all the offsets making of the address of the load
1475 Node* result = elements[0];
1476 for (int i = 1; i < count; i++) {
1477 result = igvn->transform(new AddXNode(result, elements[i]));
1478 }
1479 // Remove the constant offset from the address and then
1480 result = igvn->transform(new AddXNode(result, igvn->MakeConX(-(int)offset)));
1481 // remove the scaling of the offset to recover the original index.
1482 if (result->Opcode() == Op_LShiftX && result->in(2) == igvn->intcon(shift)) {
1483 // Peel the shift off directly but wrap it in a dummy node
1484 // since Ideal can't return existing nodes
1485 igvn->_worklist.push(result); // remove dead node later
1486 result = new RShiftXNode(result->in(1), igvn->intcon(0));
1487 } else if (result->is_Add() && result->in(2)->is_Con() &&
1488 result->in(1)->Opcode() == Op_LShiftX &&
1489 result->in(1)->in(2) == igvn->intcon(shift)) {
1490 // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z)
1491 // but for boxing cache access we know that X<<Z will not overflow
1492 // (there is range check) so we do this optimizatrion by hand here.
1493 igvn->_worklist.push(result); // remove dead node later
1494 Node* add_con = new RShiftXNode(result->in(2), igvn->intcon(shift));
1495 result = new AddXNode(result->in(1)->in(1), igvn->transform(add_con));
1496 } else {
1497 result = new RShiftXNode(result, igvn->intcon(shift));
1498 }
1499 #ifdef _LP64
1500 if (bt != T_LONG) {
1501 result = new ConvL2INode(igvn->transform(result));
1502 }
1503 #else
1504 if (bt == T_LONG) {
1505 result = new ConvI2LNode(igvn->transform(result));
1506 }
1507 #endif
1508 // Boxing/unboxing can be done from signed & unsigned loads (e.g. LoadUB -> ... -> LoadB pair).
1509 // Need to preserve unboxing load type if it is unsigned.
1510 switch(this->Opcode()) {
1511 case Op_LoadUB:
1512 result = new AndINode(igvn->transform(result), igvn->intcon(0xFF));
1513 break;
1514 case Op_LoadUS:
1515 result = new AndINode(igvn->transform(result), igvn->intcon(0xFFFF));
1516 break;
1517 }
1518 return result;
1519 }
1520 }
1521 }
1522 }
1523 }
1524 return NULL;
1525 }
1526
1527 static bool stable_phi(PhiNode* phi, PhaseGVN *phase) {
1528 Node* region = phi->in(0);
1529 if (region == NULL) {
1530 return false; // Wait stable graph
1531 }
1532 uint cnt = phi->req();
1533 for (uint i = 1; i < cnt; i++) {
1534 Node* rc = region->in(i);
1535 if (rc == NULL || phase->type(rc) == Type::TOP)
1536 return false; // Wait stable graph
1537 Node* in = phi->in(i);
1538 if (in == NULL || phase->type(in) == Type::TOP)
1539 return false; // Wait stable graph
1540 }
1541 return true;
1542 }
1543 //------------------------------split_through_phi------------------------------
1544 // Split instance or boxed field load through Phi.
1545 Node *LoadNode::split_through_phi(PhaseGVN *phase) {
1546 Node* mem = in(Memory);
1547 Node* address = in(Address);
1548 const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr();
1549
1550 assert((t_oop != NULL) &&
1551 (t_oop->is_known_instance_field() ||
1552 t_oop->is_ptr_to_boxed_value()), "invalide conditions");
1553
1554 Compile* C = phase->C;
1555 intptr_t ignore = 0;
1556 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1557 bool base_is_phi = (base != NULL) && base->is_Phi();
1558 bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() &&
1559 (base != NULL) && (base == address->in(AddPNode::Base)) &&
1560 phase->type(base)->higher_equal(TypePtr::NOTNULL);
1561
1562 if (!((mem->is_Phi() || base_is_phi) &&
1563 (load_boxed_values || t_oop->is_known_instance_field()))) {
1564 return NULL; // memory is not Phi
1565 }
1566
1567 if (mem->is_Phi()) {
1568 if (!stable_phi(mem->as_Phi(), phase)) {
1569 return NULL; // Wait stable graph
1570 }
1571 uint cnt = mem->req();
1572 // Check for loop invariant memory.
1573 if (cnt == 3) {
1574 for (uint i = 1; i < cnt; i++) {
1575 Node* in = mem->in(i);
1576 Node* m = optimize_memory_chain(in, t_oop, this, phase);
1577 if (m == mem) {
1578 if (i == 1) {
1579 // if the first edge was a loop, check second edge too.
1580 // If both are replaceable - we are in an infinite loop
1581 Node *n = optimize_memory_chain(mem->in(2), t_oop, this, phase);
1582 if (n == mem) {
1583 break;
1584 }
1585 }
1586 set_req(Memory, mem->in(cnt - i));
1587 return this; // made change
1588 }
1589 }
1590 }
1591 }
1592 if (base_is_phi) {
1593 if (!stable_phi(base->as_Phi(), phase)) {
1594 return NULL; // Wait stable graph
1595 }
1596 uint cnt = base->req();
1597 // Check for loop invariant memory.
1598 if (cnt == 3) {
1599 for (uint i = 1; i < cnt; i++) {
1600 if (base->in(i) == base) {
1601 return NULL; // Wait stable graph
1602 }
1603 }
1604 }
1605 }
1606
1607 // Split through Phi (see original code in loopopts.cpp).
1608 assert(C->have_alias_type(t_oop), "instance should have alias type");
1609
1610 // Do nothing here if Identity will find a value
1611 // (to avoid infinite chain of value phis generation).
1612 if (this != Identity(phase)) {
1613 return NULL;
1614 }
1615
1616 // Select Region to split through.
1617 Node* region;
1618 if (!base_is_phi) {
1619 assert(mem->is_Phi(), "sanity");
1620 region = mem->in(0);
1621 // Skip if the region dominates some control edge of the address.
1622 if (!MemNode::all_controls_dominate(address, region))
1623 return NULL;
1624 } else if (!mem->is_Phi()) {
1625 assert(base_is_phi, "sanity");
1626 region = base->in(0);
1627 // Skip if the region dominates some control edge of the memory.
1628 if (!MemNode::all_controls_dominate(mem, region))
1629 return NULL;
1630 } else if (base->in(0) != mem->in(0)) {
1631 assert(base_is_phi && mem->is_Phi(), "sanity");
1632 if (MemNode::all_controls_dominate(mem, base->in(0))) {
1633 region = base->in(0);
1634 } else if (MemNode::all_controls_dominate(address, mem->in(0))) {
1635 region = mem->in(0);
1636 } else {
1637 return NULL; // complex graph
1638 }
1639 } else {
1640 assert(base->in(0) == mem->in(0), "sanity");
1641 region = mem->in(0);
1642 }
1643
1644 const Type* this_type = this->bottom_type();
1645 int this_index = C->get_alias_index(t_oop);
1646 int this_offset = t_oop->offset();
1647 int this_iid = t_oop->instance_id();
1648 if (!t_oop->is_known_instance() && load_boxed_values) {
1649 // Use _idx of address base for boxed values.
1650 this_iid = base->_idx;
1651 }
1652 PhaseIterGVN* igvn = phase->is_IterGVN();
1653 Node* phi = new PhiNode(region, this_type, NULL, mem->_idx, this_iid, this_index, this_offset);
1654 for (uint i = 1; i < region->req(); i++) {
1655 Node* x;
1656 Node* the_clone = NULL;
1657 Node* in = region->in(i);
1658 if (region->is_CountedLoop() && region->as_Loop()->is_strip_mined() && i == LoopNode::EntryControl &&
1659 in != NULL && in->is_OuterStripMinedLoop()) {
1660 // No node should go in the outer strip mined loop
1661 in = in->in(LoopNode::EntryControl);
1662 }
1663 if (in == NULL || in == C->top()) {
1664 x = C->top(); // Dead path? Use a dead data op
1665 } else {
1666 x = this->clone(); // Else clone up the data op
1667 the_clone = x; // Remember for possible deletion.
1668 // Alter data node to use pre-phi inputs
1669 if (this->in(0) == region) {
1670 if (mem->is_Phi() && (mem->in(0) == region) && mem->in(i)->in(0) != NULL &&
1671 MemNode::all_controls_dominate(address, region)) {
1672 // Enable other optimizations such as loop predication which does not work
1673 // if we directly pin the node to node `in`
1674 x->set_req(0, mem->in(i)->in(0)); // Use same control as memory
1675 } else {
1676 x->set_req(0, in);
1677 }
1678 } else {
1679 x->set_req(0, NULL);
1680 }
1681 if (mem->is_Phi() && (mem->in(0) == region)) {
1682 x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone.
1683 }
1684 if (address->is_Phi() && address->in(0) == region) {
1685 x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone
1686 }
1687 if (base_is_phi && (base->in(0) == region)) {
1688 Node* base_x = base->in(i); // Clone address for loads from boxed objects.
1689 Node* adr_x = phase->transform(new AddPNode(base_x,base_x,address->in(AddPNode::Offset)));
1690 x->set_req(Address, adr_x);
1691 }
1692 }
1693 // Check for a 'win' on some paths
1694 const Type *t = x->Value(igvn);
1695
1696 bool singleton = t->singleton();
1697
1698 // See comments in PhaseIdealLoop::split_thru_phi().
1699 if (singleton && t == Type::TOP) {
1700 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1701 }
1702
1703 if (singleton) {
1704 x = igvn->makecon(t);
1705 } else {
1706 // We now call Identity to try to simplify the cloned node.
1707 // Note that some Identity methods call phase->type(this).
1708 // Make sure that the type array is big enough for
1709 // our new node, even though we may throw the node away.
1710 // (This tweaking with igvn only works because x is a new node.)
1711 igvn->set_type(x, t);
1712 // If x is a TypeNode, capture any more-precise type permanently into Node
1713 // otherwise it will be not updated during igvn->transform since
1714 // igvn->type(x) is set to x->Value() already.
1715 x->raise_bottom_type(t);
1716 Node* y = x->Identity(igvn);
1717 if (y != x) {
1718 x = y;
1719 } else {
1720 y = igvn->hash_find_insert(x);
1721 if (y) {
1722 x = y;
1723 } else {
1724 // Else x is a new node we are keeping
1725 // We do not need register_new_node_with_optimizer
1726 // because set_type has already been called.
1727 igvn->_worklist.push(x);
1728 }
1729 }
1730 }
1731 if (x != the_clone && the_clone != NULL) {
1732 igvn->remove_dead_node(the_clone);
1733 }
1734 phi->set_req(i, x);
1735 }
1736 // Record Phi
1737 igvn->register_new_node_with_optimizer(phi);
1738 return phi;
1739 }
1740
1741 AllocateNode* LoadNode::is_new_object_mark_load(PhaseGVN *phase) const {
1742 if (Opcode() == Op_LoadX) {
1743 Node* address = in(MemNode::Address);
1744 AllocateNode* alloc = AllocateNode::Ideal_allocation(address, phase);
1745 Node* mem = in(MemNode::Memory);
1746 if (alloc != NULL && mem->is_Proj() &&
1747 mem->in(0) != NULL &&
1748 mem->in(0) == alloc->initialization() &&
1749 alloc->initialization()->proj_out_or_null(0) != NULL) {
1750 return alloc;
1751 }
1752 }
1753 return NULL;
1754 }
1755
1756
1757 //------------------------------Ideal------------------------------------------
1758 // If the load is from Field memory and the pointer is non-null, it might be possible to
1759 // zero out the control input.
1760 // If the offset is constant and the base is an object allocation,
1761 // try to hook me up to the exact initializing store.
1762 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1763 Node* p = MemNode::Ideal_common(phase, can_reshape);
1764 if (p) return (p == NodeSentinel) ? NULL : p;
1765
1766 Node* ctrl = in(MemNode::Control);
1767 Node* address = in(MemNode::Address);
1768 bool progress = false;
1769
1770 bool addr_mark = ((phase->type(address)->isa_oopptr() || phase->type(address)->isa_narrowoop()) &&
1771 phase->type(address)->is_ptr()->offset() == oopDesc::mark_offset_in_bytes());
1772
1773 // Skip up past a SafePoint control. Cannot do this for Stores because
1774 // pointer stores & cardmarks must stay on the same side of a SafePoint.
1775 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint &&
1776 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw &&
1777 !addr_mark &&
1778 (depends_only_on_test() || has_unknown_control_dependency())) {
1779 ctrl = ctrl->in(0);
1780 set_req(MemNode::Control,ctrl);
1781 progress = true;
1782 }
1783
1784 intptr_t ignore = 0;
1785 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1786 if (base != NULL
1787 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
1788 // Check for useless control edge in some common special cases
1789 if (in(MemNode::Control) != NULL
1790 && can_remove_control()
1791 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1792 && all_controls_dominate(base, phase->C->start())) {
1793 // A method-invariant, non-null address (constant or 'this' argument).
1794 set_req(MemNode::Control, NULL);
1795 progress = true;
1796 }
1797 }
1798
1799 Node* mem = in(MemNode::Memory);
1800 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1801
1802 if (can_reshape && (addr_t != NULL)) {
1803 // try to optimize our memory input
1804 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase);
1805 if (opt_mem != mem) {
1806 set_req_X(MemNode::Memory, opt_mem, phase);
1807 if (phase->type( opt_mem ) == Type::TOP) return NULL;
1808 return this;
1809 }
1810 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1811 if ((t_oop != NULL) &&
1812 (t_oop->is_known_instance_field() ||
1813 t_oop->is_ptr_to_boxed_value())) {
1814 PhaseIterGVN *igvn = phase->is_IterGVN();
1815 assert(igvn != NULL, "must be PhaseIterGVN when can_reshape is true");
1816 if (igvn->_worklist.member(opt_mem)) {
1817 // Delay this transformation until memory Phi is processed.
1818 igvn->_worklist.push(this);
1819 return NULL;
1820 }
1821 // Split instance field load through Phi.
1822 Node* result = split_through_phi(phase);
1823 if (result != NULL) return result;
1824
1825 if (t_oop->is_ptr_to_boxed_value()) {
1826 Node* result = eliminate_autobox(igvn);
1827 if (result != NULL) return result;
1828 }
1829 }
1830 }
1831
1832 // Is there a dominating load that loads the same value? Leave
1833 // anything that is not a load of a field/array element (like
1834 // barriers etc.) alone
1835 if (in(0) != NULL && !adr_type()->isa_rawptr() && can_reshape) {
1836 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) {
1837 Node *use = mem->fast_out(i);
1838 if (use != this &&
1839 use->Opcode() == Opcode() &&
1840 use->in(0) != NULL &&
1841 use->in(0) != in(0) &&
1842 use->in(Address) == in(Address)) {
1843 Node* ctl = in(0);
1844 for (int i = 0; i < 10 && ctl != NULL; i++) {
1845 ctl = IfNode::up_one_dom(ctl);
1846 if (ctl == use->in(0)) {
1847 set_req(0, use->in(0));
1848 return this;
1849 }
1850 }
1851 }
1852 }
1853 }
1854
1855 // Check for prior store with a different base or offset; make Load
1856 // independent. Skip through any number of them. Bail out if the stores
1857 // are in an endless dead cycle and report no progress. This is a key
1858 // transform for Reflection. However, if after skipping through the Stores
1859 // we can't then fold up against a prior store do NOT do the transform as
1860 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
1861 // array memory alive twice: once for the hoisted Load and again after the
1862 // bypassed Store. This situation only works if EVERYBODY who does
1863 // anti-dependence work knows how to bypass. I.e. we need all
1864 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
1865 // the alias index stuff. So instead, peek through Stores and IFF we can
1866 // fold up, do so.
1867 Node* prev_mem = find_previous_store(phase);
1868 if (prev_mem != NULL) {
1869 Node* value = can_see_arraycopy_value(prev_mem, phase);
1870 if (value != NULL) {
1871 return value;
1872 }
1873 }
1874 // Steps (a), (b): Walk past independent stores to find an exact match.
1875 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) {
1876 // (c) See if we can fold up on the spot, but don't fold up here.
1877 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
1878 // just return a prior value, which is done by Identity calls.
1879 if (can_see_stored_value(prev_mem, phase)) {
1880 // Make ready for step (d):
1881 set_req_X(MemNode::Memory, prev_mem, phase);
1882 return this;
1883 }
1884 }
1885
1886 return progress ? this : NULL;
1887 }
1888
1889 // Helper to recognize certain Klass fields which are invariant across
1890 // some group of array types (e.g., int[] or all T[] where T < Object).
1891 const Type*
1892 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1893 ciKlass* klass) const {
1894 if (tkls->offset() == in_bytes(Klass::modifier_flags_offset())) {
1895 // The field is Klass::_modifier_flags. Return its (constant) value.
1896 // (Folds up the 2nd indirection in aClassConstant.getModifiers().)
1897 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags");
1898 return TypeInt::make(klass->modifier_flags());
1899 }
1900 if (tkls->offset() == in_bytes(Klass::access_flags_offset())) {
1901 // The field is Klass::_access_flags. Return its (constant) value.
1902 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1903 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags");
1904 return TypeInt::make(klass->access_flags());
1905 }
1906 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) {
1907 // The field is Klass::_layout_helper. Return its constant value if known.
1908 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper");
1909 return TypeInt::make(klass->layout_helper());
1910 }
1911
1912 // No match.
1913 return NULL;
1914 }
1915
1916 //------------------------------Value-----------------------------------------
1917 const Type* LoadNode::Value(PhaseGVN* phase) const {
1918 // Either input is TOP ==> the result is TOP
1919 Node* mem = in(MemNode::Memory);
1920 const Type *t1 = phase->type(mem);
1921 if (t1 == Type::TOP) return Type::TOP;
1922 Node* adr = in(MemNode::Address);
1923 const TypePtr* tp = phase->type(adr)->isa_ptr();
1924 if (tp == NULL || tp->empty()) return Type::TOP;
1925 int off = tp->offset();
1926 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
1927 Compile* C = phase->C;
1928
1929 // Try to guess loaded type from pointer type
1930 if (tp->isa_aryptr()) {
1931 const TypeAryPtr* ary = tp->is_aryptr();
1932 const Type* t = ary->elem();
1933
1934 // Determine whether the reference is beyond the header or not, by comparing
1935 // the offset against the offset of the start of the array's data.
1936 // Different array types begin at slightly different offsets (12 vs. 16).
1937 // We choose T_BYTE as an example base type that is least restrictive
1938 // as to alignment, which will therefore produce the smallest
1939 // possible base offset.
1940 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
1941 const bool off_beyond_header = (off >= min_base_off);
1942
1943 // Try to constant-fold a stable array element.
1944 if (FoldStableValues && !is_mismatched_access() && ary->is_stable()) {
1945 // Make sure the reference is not into the header and the offset is constant
1946 ciObject* aobj = ary->const_oop();
1947 if (aobj != NULL && off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) {
1948 int stable_dimension = (ary->stable_dimension() > 0 ? ary->stable_dimension() - 1 : 0);
1949 const Type* con_type = Type::make_constant_from_array_element(aobj->as_array(), off,
1950 stable_dimension,
1951 memory_type(), is_unsigned());
1952 if (con_type != NULL) {
1953 return con_type;
1954 }
1955 }
1956 }
1957
1958 // Don't do this for integer types. There is only potential profit if
1959 // the element type t is lower than _type; that is, for int types, if _type is
1960 // more restrictive than t. This only happens here if one is short and the other
1961 // char (both 16 bits), and in those cases we've made an intentional decision
1962 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
1963 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
1964 //
1965 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
1966 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
1967 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
1968 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
1969 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
1970 // In fact, that could have been the original type of p1, and p1 could have
1971 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
1972 // expression (LShiftL quux 3) independently optimized to the constant 8.
1973 if ((t->isa_int() == NULL) && (t->isa_long() == NULL)
1974 && (_type->isa_vect() == NULL)
1975 && t->isa_inlinetype() == NULL
1976 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
1977 // t might actually be lower than _type, if _type is a unique
1978 // concrete subclass of abstract class t.
1979 if (off_beyond_header || off == Type::OffsetBot) { // is the offset beyond the header?
1980 const Type* jt = t->join_speculative(_type);
1981 // In any case, do not allow the join, per se, to empty out the type.
1982 if (jt->empty() && !t->empty()) {
1983 // This can happen if a interface-typed array narrows to a class type.
1984 jt = _type;
1985 }
1986 #ifdef ASSERT
1987 if (phase->C->eliminate_boxing() && adr->is_AddP()) {
1988 // The pointers in the autobox arrays are always non-null
1989 Node* base = adr->in(AddPNode::Base);
1990 if ((base != NULL) && base->is_DecodeN()) {
1991 // Get LoadN node which loads IntegerCache.cache field
1992 base = base->in(1);
1993 }
1994 if ((base != NULL) && base->is_Con()) {
1995 const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr();
1996 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1997 // It could be narrow oop
1998 assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity");
1999 }
2000 }
2001 }
2002 #endif
2003 return jt;
2004 }
2005 }
2006 } else if (tp->base() == Type::InstPtr) {
2007 assert( off != Type::OffsetBot ||
2008 // arrays can be cast to Objects
2009 tp->is_oopptr()->klass()->is_java_lang_Object() ||
2010 tp->is_oopptr()->klass() == ciEnv::current()->Class_klass() ||
2011 // unsafe field access may not have a constant offset
2012 C->has_unsafe_access(),
2013 "Field accesses must be precise" );
2014 // For oop loads, we expect the _type to be precise.
2015
2016 const TypeInstPtr* tinst = tp->is_instptr();
2017 BasicType bt = memory_type();
2018
2019 // Optimize loads from constant fields.
2020 ciObject* const_oop = tinst->const_oop();
2021 if (!is_mismatched_access() && off != Type::OffsetBot && const_oop != NULL && const_oop->is_instance()) {
2022 ciType* mirror_type = const_oop->as_instance()->java_mirror_type();
2023 if (mirror_type != NULL) {
2024 const Type* const_oop = NULL;
2025 ciInlineKlass* vk = mirror_type->is_inlinetype() ? mirror_type->as_inline_klass() : NULL;
2026 // Fold default value loads
2027 if (vk != NULL && off == vk->default_value_offset()) {
2028 const_oop = TypeInstPtr::make(vk->default_instance());
2029 }
2030 // Fold class mirror loads
2031 if (off == java_lang_Class::primary_mirror_offset()) {
2032 const_oop = (vk == NULL) ? TypePtr::NULL_PTR : TypeInstPtr::make(vk->ref_instance());
2033 } else if (off == java_lang_Class::secondary_mirror_offset()) {
2034 const_oop = (vk == NULL) ? TypePtr::NULL_PTR : TypeInstPtr::make(vk->val_instance());
2035 }
2036 if (const_oop != NULL) {
2037 return (bt == T_NARROWOOP) ? const_oop->make_narrowoop() : const_oop;
2038 }
2039 }
2040 const Type* con_type = Type::make_constant_from_field(const_oop->as_instance(), off, is_unsigned(), bt);
2041 if (con_type != NULL) {
2042 return con_type;
2043 }
2044 }
2045 } else if (tp->base() == Type::KlassPtr || tp->base() == Type::InstKlassPtr || tp->base() == Type::AryKlassPtr) {
2046 assert( off != Type::OffsetBot ||
2047 // arrays can be cast to Objects
2048 tp->is_klassptr()->klass() == NULL ||
2049 tp->is_klassptr()->klass()->is_java_lang_Object() ||
2050 // also allow array-loading from the primary supertype
2051 // array during subtype checks
2052 Opcode() == Op_LoadKlass,
2053 "Field accesses must be precise" );
2054 // For klass/static loads, we expect the _type to be precise
2055 } else if (tp->base() == Type::RawPtr && !StressReflectiveCode) {
2056 if (adr->is_Load() && off == 0) {
2057 /* With mirrors being an indirect in the Klass*
2058 * the VM is now using two loads. LoadKlass(LoadP(LoadP(Klass, mirror_offset), zero_offset))
2059 * The LoadP from the Klass has a RawPtr type (see LibraryCallKit::load_mirror_from_klass).
2060 *
2061 * So check the type and klass of the node before the LoadP.
2062 */
2063 Node* adr2 = adr->in(MemNode::Address);
2064 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2065 if (tkls != NULL) {
2066 ciKlass* klass = tkls->klass();
2067 if (klass != NULL && klass->is_loaded() && tkls->klass_is_exact() && tkls->offset() == in_bytes(Klass::java_mirror_offset())) {
2068 assert(adr->Opcode() == Op_LoadP, "must load an oop from _java_mirror");
2069 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
2070 return TypeInstPtr::make(klass->java_mirror());
2071 }
2072 }
2073 } else {
2074 // Check for a load of the default value offset from the InlineKlassFixedBlock:
2075 // LoadI(LoadP(inline_klass, adr_inlineklass_fixed_block_offset), default_value_offset_offset)
2076 intptr_t offset = 0;
2077 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2078 if (base != NULL && base->is_Load() && offset == in_bytes(InlineKlass::default_value_offset_offset())) {
2079 const TypeKlassPtr* tkls = phase->type(base->in(MemNode::Address))->isa_klassptr();
2080 if (tkls != NULL && tkls->is_loaded() && tkls->klass_is_exact() && tkls->isa_inlinetype() &&
2081 tkls->offset() == in_bytes(InstanceKlass::adr_inlineklass_fixed_block_offset())) {
2082 assert(base->Opcode() == Op_LoadP, "must load an oop from klass");
2083 assert(Opcode() == Op_LoadI, "must load an int from fixed block");
2084 return TypeInt::make(tkls->klass()->as_inline_klass()->default_value_offset());
2085 }
2086 }
2087 }
2088 }
2089
2090 const TypeKlassPtr *tkls = tp->isa_klassptr();
2091 if (tkls != NULL && !StressReflectiveCode) {
2092 ciKlass* klass = tkls->klass();
2093 if (tkls->is_loaded() && tkls->klass_is_exact()) {
2094 // We are loading a field from a Klass metaobject whose identity
2095 // is known at compile time (the type is "exact" or "precise").
2096 // Check for fields we know are maintained as constants by the VM.
2097 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) {
2098 // The field is Klass::_super_check_offset. Return its (constant) value.
2099 // (Folds up type checking code.)
2100 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
2101 return TypeInt::make(klass->super_check_offset());
2102 }
2103 // Compute index into primary_supers array
2104 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
2105 // Check for overflowing; use unsigned compare to handle the negative case.
2106 if( depth < ciKlass::primary_super_limit() ) {
2107 // The field is an element of Klass::_primary_supers. Return its (constant) value.
2108 // (Folds up type checking code.)
2109 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
2110 ciKlass *ss = klass->super_of_depth(depth);
2111 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
2112 }
2113 const Type* aift = load_array_final_field(tkls, klass);
2114 if (aift != NULL) return aift;
2115 }
2116
2117 // We can still check if we are loading from the primary_supers array at a
2118 // shallow enough depth. Even though the klass is not exact, entries less
2119 // than or equal to its super depth are correct.
2120 if (tkls->is_loaded()) {
2121 ciType *inner = klass;
2122 while( inner->is_obj_array_klass() )
2123 inner = inner->as_obj_array_klass()->base_element_type();
2124 if( inner->is_instance_klass() &&
2125 !inner->as_instance_klass()->flags().is_interface() ) {
2126 // Compute index into primary_supers array
2127 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
2128 // Check for overflowing; use unsigned compare to handle the negative case.
2129 if( depth < ciKlass::primary_super_limit() &&
2130 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case
2131 // The field is an element of Klass::_primary_supers. Return its (constant) value.
2132 // (Folds up type checking code.)
2133 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
2134 ciKlass *ss = klass->super_of_depth(depth);
2135 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
2136 }
2137 }
2138 }
2139
2140 // If the type is enough to determine that the thing is not an array,
2141 // we can give the layout_helper a positive interval type.
2142 // This will help short-circuit some reflective code.
2143 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())
2144 && !klass->is_array_klass() // not directly typed as an array
2145 && !klass->is_interface() // specifically not Serializable & Cloneable
2146 && !klass->is_java_lang_Object() // not the supertype of all T[]
2147 ) {
2148 // Note: When interfaces are reliable, we can narrow the interface
2149 // test to (klass != Serializable && klass != Cloneable).
2150 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
2151 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
2152 // The key property of this type is that it folds up tests
2153 // for array-ness, since it proves that the layout_helper is positive.
2154 // Thus, a generic value like the basic object layout helper works fine.
2155 return TypeInt::make(min_size, max_jint, Type::WidenMin);
2156 }
2157 }
2158
2159 // If we are loading from a freshly-allocated object, produce a zero,
2160 // if the load is provably beyond the header of the object.
2161 // (Also allow a variable load from a fresh array to produce zero.)
2162 const TypeOopPtr *tinst = tp->isa_oopptr();
2163 bool is_instance = (tinst != NULL) && tinst->is_known_instance_field();
2164 bool is_boxed_value = (tinst != NULL) && tinst->is_ptr_to_boxed_value();
2165 if (ReduceFieldZeroing || is_instance || is_boxed_value) {
2166 Node* value = can_see_stored_value(mem,phase);
2167 if (value != NULL && value->is_Con()) {
2168 assert(value->bottom_type()->higher_equal(_type),"sanity");
2169 return value->bottom_type();
2170 }
2171 }
2172
2173 bool is_vect = (_type->isa_vect() != NULL);
2174 if (is_instance && !is_vect) {
2175 // If we have an instance type and our memory input is the
2176 // programs's initial memory state, there is no matching store,
2177 // so just return a zero of the appropriate type -
2178 // except if it is vectorized - then we have no zero constant.
2179 Node *mem = in(MemNode::Memory);
2180 if (mem->is_Parm() && mem->in(0)->is_Start()) {
2181 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
2182 return Type::get_zero_type(_type->basic_type());
2183 }
2184 }
2185 Node* alloc = is_new_object_mark_load(phase);
2186 if (alloc != NULL) {
2187 if (EnableValhalla) {
2188 // The mark word may contain property bits (inline, flat, null-free)
2189 Node* klass_node = alloc->in(AllocateNode::KlassNode);
2190 const TypeKlassPtr* tkls = phase->type(klass_node)->is_klassptr();
2191 ciKlass* klass = tkls->klass();
2192 if (klass != NULL && klass->is_loaded() && tkls->klass_is_exact()) {
2193 return TypeX::make(klass->prototype_header().value());
2194 }
2195 } else {
2196 return TypeX::make(markWord::prototype().value());
2197 }
2198 }
2199
2200 return _type;
2201 }
2202
2203 //------------------------------match_edge-------------------------------------
2204 // Do we Match on this edge index or not? Match only the address.
2205 uint LoadNode::match_edge(uint idx) const {
2206 return idx == MemNode::Address;
2207 }
2208
2209 //--------------------------LoadBNode::Ideal--------------------------------------
2210 //
2211 // If the previous store is to the same address as this load,
2212 // and the value stored was larger than a byte, replace this load
2213 // with the value stored truncated to a byte. If no truncation is
2214 // needed, the replacement is done in LoadNode::Identity().
2215 //
2216 Node* LoadBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2217 Node* mem = in(MemNode::Memory);
2218 Node* value = can_see_stored_value(mem,phase);
2219 if (value != NULL) {
2220 Node* narrow = Compile::narrow_value(T_BYTE, value, _type, phase, false);
2221 if (narrow != value) {
2222 return narrow;
2223 }
2224 }
2225 // Identity call will handle the case where truncation is not needed.
2226 return LoadNode::Ideal(phase, can_reshape);
2227 }
2228
2229 const Type* LoadBNode::Value(PhaseGVN* phase) const {
2230 Node* mem = in(MemNode::Memory);
2231 Node* value = can_see_stored_value(mem,phase);
2232 if (value != NULL && value->is_Con() &&
2233 !value->bottom_type()->higher_equal(_type)) {
2234 // If the input to the store does not fit with the load's result type,
2235 // it must be truncated. We can't delay until Ideal call since
2236 // a singleton Value is needed for split_thru_phi optimization.
2237 int con = value->get_int();
2238 return TypeInt::make((con << 24) >> 24);
2239 }
2240 return LoadNode::Value(phase);
2241 }
2242
2243 //--------------------------LoadUBNode::Ideal-------------------------------------
2244 //
2245 // If the previous store is to the same address as this load,
2246 // and the value stored was larger than a byte, replace this load
2247 // with the value stored truncated to a byte. If no truncation is
2248 // needed, the replacement is done in LoadNode::Identity().
2249 //
2250 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2251 Node* mem = in(MemNode::Memory);
2252 Node* value = can_see_stored_value(mem, phase);
2253 if (value != NULL) {
2254 Node* narrow = Compile::narrow_value(T_BOOLEAN, value, _type, phase, false);
2255 if (narrow != value) {
2256 return narrow;
2257 }
2258 }
2259 // Identity call will handle the case where truncation is not needed.
2260 return LoadNode::Ideal(phase, can_reshape);
2261 }
2262
2263 const Type* LoadUBNode::Value(PhaseGVN* phase) const {
2264 Node* mem = in(MemNode::Memory);
2265 Node* value = can_see_stored_value(mem,phase);
2266 if (value != NULL && value->is_Con() &&
2267 !value->bottom_type()->higher_equal(_type)) {
2268 // If the input to the store does not fit with the load's result type,
2269 // it must be truncated. We can't delay until Ideal call since
2270 // a singleton Value is needed for split_thru_phi optimization.
2271 int con = value->get_int();
2272 return TypeInt::make(con & 0xFF);
2273 }
2274 return LoadNode::Value(phase);
2275 }
2276
2277 //--------------------------LoadUSNode::Ideal-------------------------------------
2278 //
2279 // If the previous store is to the same address as this load,
2280 // and the value stored was larger than a char, replace this load
2281 // with the value stored truncated to a char. If no truncation is
2282 // needed, the replacement is done in LoadNode::Identity().
2283 //
2284 Node* LoadUSNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2285 Node* mem = in(MemNode::Memory);
2286 Node* value = can_see_stored_value(mem,phase);
2287 if (value != NULL) {
2288 Node* narrow = Compile::narrow_value(T_CHAR, value, _type, phase, false);
2289 if (narrow != value) {
2290 return narrow;
2291 }
2292 }
2293 // Identity call will handle the case where truncation is not needed.
2294 return LoadNode::Ideal(phase, can_reshape);
2295 }
2296
2297 const Type* LoadUSNode::Value(PhaseGVN* phase) const {
2298 Node* mem = in(MemNode::Memory);
2299 Node* value = can_see_stored_value(mem,phase);
2300 if (value != NULL && value->is_Con() &&
2301 !value->bottom_type()->higher_equal(_type)) {
2302 // If the input to the store does not fit with the load's result type,
2303 // it must be truncated. We can't delay until Ideal call since
2304 // a singleton Value is needed for split_thru_phi optimization.
2305 int con = value->get_int();
2306 return TypeInt::make(con & 0xFFFF);
2307 }
2308 return LoadNode::Value(phase);
2309 }
2310
2311 //--------------------------LoadSNode::Ideal--------------------------------------
2312 //
2313 // If the previous store is to the same address as this load,
2314 // and the value stored was larger than a short, replace this load
2315 // with the value stored truncated to a short. If no truncation is
2316 // needed, the replacement is done in LoadNode::Identity().
2317 //
2318 Node* LoadSNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2319 Node* mem = in(MemNode::Memory);
2320 Node* value = can_see_stored_value(mem,phase);
2321 if (value != NULL) {
2322 Node* narrow = Compile::narrow_value(T_SHORT, value, _type, phase, false);
2323 if (narrow != value) {
2324 return narrow;
2325 }
2326 }
2327 // Identity call will handle the case where truncation is not needed.
2328 return LoadNode::Ideal(phase, can_reshape);
2329 }
2330
2331 const Type* LoadSNode::Value(PhaseGVN* phase) const {
2332 Node* mem = in(MemNode::Memory);
2333 Node* value = can_see_stored_value(mem,phase);
2334 if (value != NULL && value->is_Con() &&
2335 !value->bottom_type()->higher_equal(_type)) {
2336 // If the input to the store does not fit with the load's result type,
2337 // it must be truncated. We can't delay until Ideal call since
2338 // a singleton Value is needed for split_thru_phi optimization.
2339 int con = value->get_int();
2340 return TypeInt::make((con << 16) >> 16);
2341 }
2342 return LoadNode::Value(phase);
2343 }
2344
2345 //=============================================================================
2346 //----------------------------LoadKlassNode::make------------------------------
2347 // Polymorphic factory method:
2348 Node* LoadKlassNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* at,
2349 const TypeKlassPtr* tk) {
2350 // sanity check the alias category against the created node type
2351 const TypePtr *adr_type = adr->bottom_type()->isa_ptr();
2352 assert(adr_type != NULL, "expecting TypeKlassPtr");
2353 #ifdef _LP64
2354 if (adr_type->is_ptr_to_narrowklass()) {
2355 assert(UseCompressedClassPointers, "no compressed klasses");
2356 Node* load_klass = gvn.transform(new LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowklass(), MemNode::unordered));
2357 return new DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr());
2358 }
2359 #endif
2360 assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
2361 return new LoadKlassNode(ctl, mem, adr, at, tk, MemNode::unordered);
2362 }
2363
2364 //------------------------------Value------------------------------------------
2365 const Type* LoadKlassNode::Value(PhaseGVN* phase) const {
2366 return klass_value_common(phase);
2367 }
2368
2369 // In most cases, LoadKlassNode does not have the control input set. If the control
2370 // input is set, it must not be removed (by LoadNode::Ideal()).
2371 bool LoadKlassNode::can_remove_control() const {
2372 return false;
2373 }
2374
2375 const Type* LoadNode::klass_value_common(PhaseGVN* phase) const {
2376 // Either input is TOP ==> the result is TOP
2377 const Type *t1 = phase->type( in(MemNode::Memory) );
2378 if (t1 == Type::TOP) return Type::TOP;
2379 Node *adr = in(MemNode::Address);
2380 const Type *t2 = phase->type( adr );
2381 if (t2 == Type::TOP) return Type::TOP;
2382 const TypePtr *tp = t2->is_ptr();
2383 if (TypePtr::above_centerline(tp->ptr()) ||
2384 tp->ptr() == TypePtr::Null) return Type::TOP;
2385
2386 // Return a more precise klass, if possible
2387 const TypeInstPtr *tinst = tp->isa_instptr();
2388 if (tinst != NULL) {
2389 ciInstanceKlass* ik = tinst->klass()->as_instance_klass();
2390 int offset = tinst->offset();
2391 if (ik == phase->C->env()->Class_klass()
2392 && (offset == java_lang_Class::klass_offset() ||
2393 offset == java_lang_Class::array_klass_offset())) {
2394 // We are loading a special hidden field from a Class mirror object,
2395 // the field which points to the VM's Klass metaobject.
2396 bool null_free = false;
2397 ciType* t = tinst->java_mirror_type(&null_free);
2398 // java_mirror_type returns non-null for compile-time Class constants.
2399 if (t != NULL) {
2400 // constant oop => constant klass
2401 if (offset == java_lang_Class::array_klass_offset()) {
2402 if (t->is_void()) {
2403 // We cannot create a void array. Since void is a primitive type return null
2404 // klass. Users of this result need to do a null check on the returned klass.
2405 return TypePtr::NULL_PTR;
2406 }
2407 return TypeKlassPtr::make(ciArrayKlass::make(t, null_free));
2408 }
2409 if (!t->is_klass()) {
2410 // a primitive Class (e.g., int.class) has NULL for a klass field
2411 return TypePtr::NULL_PTR;
2412 }
2413 // (Folds up the 1st indirection in aClassConstant.getModifiers().)
2414 return TypeKlassPtr::make(t->as_klass());
2415 }
2416 // non-constant mirror, so we can't tell what's going on
2417 }
2418 if( !ik->is_loaded() )
2419 return _type; // Bail out if not loaded
2420 if (offset == oopDesc::klass_offset_in_bytes()) {
2421 if (tinst->klass_is_exact()) {
2422 return TypeKlassPtr::make(ik);
2423 }
2424 // See if we can become precise: no subklasses and no interface
2425 // (Note: We need to support verified interfaces.)
2426 if (!ik->is_interface() && !ik->has_subklass()) {
2427 // Add a dependence; if any subclass added we need to recompile
2428 if (!ik->is_final()) {
2429 // %%% should use stronger assert_unique_concrete_subtype instead
2430 phase->C->dependencies()->assert_leaf_type(ik);
2431 }
2432 // Return precise klass
2433 return TypeKlassPtr::make(ik);
2434 }
2435
2436 // Return root of possible klass
2437 return TypeInstKlassPtr::make(TypePtr::NotNull, ik, Type::Offset(0), tinst->flatten_array());
2438 }
2439 }
2440
2441 // Check for loading klass from an array
2442 const TypeAryPtr *tary = tp->isa_aryptr();
2443 if (tary != NULL) {
2444 ciKlass *tary_klass = tary->klass();
2445 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP
2446 && tary->offset() == oopDesc::klass_offset_in_bytes()) {
2447 if (tary->klass_is_exact()) {
2448 return TypeKlassPtr::make(tary_klass);
2449 }
2450 ciArrayKlass* ak = tary_klass->as_array_klass();
2451 // If the klass is an object array, we defer the question to the
2452 // array component klass.
2453 if (ak->is_obj_array_klass()) {
2454 assert(ak->is_loaded(), "");
2455 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass();
2456 if (base_k->is_loaded() && base_k->is_instance_klass()) {
2457 ciInstanceKlass *ik = base_k->as_instance_klass();
2458 // See if we can become precise: no subklasses and no interface
2459 // Do not fold klass loads from [LMyValue. The runtime type might be [QMyValue due to [QMyValue <: [LMyValue
2460 // and the klass for [QMyValue is not equal to the klass for [LMyValue.
2461 if (!ik->is_interface() && !ik->has_subklass() && (!ik->is_inlinetype() || ak->is_elem_null_free())) {
2462 // Add a dependence; if any subclass added we need to recompile
2463 if (!ik->is_final()) {
2464 phase->C->dependencies()->assert_leaf_type(ik);
2465 }
2466 // Return precise array klass
2467 return TypeKlassPtr::make(ak);
2468 }
2469 }
2470 return TypeAryKlassPtr::make(TypePtr::NotNull, ak, Type::Offset(0), tary->is_not_flat(), tary->is_not_null_free(), tary->is_null_free());
2471 } else if (ak->is_type_array_klass()) {
2472 return TypeKlassPtr::make(ak); // These are always precise
2473 }
2474 }
2475 }
2476
2477 // Check for loading klass from an array klass
2478 const TypeKlassPtr *tkls = tp->isa_klassptr();
2479 if (tkls != NULL && !StressReflectiveCode) {
2480 if (!tkls->is_loaded()) {
2481 return _type; // Bail out if not loaded
2482 }
2483 ciKlass* klass = tkls->klass();
2484 if( klass->is_obj_array_klass() &&
2485 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) {
2486 ciKlass* elem = klass->as_obj_array_klass()->element_klass();
2487 // // Always returning precise element type is incorrect,
2488 // // e.g., element type could be object and array may contain strings
2489 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
2490
2491 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
2492 // according to the element type's subclassing.
2493 return TypeKlassPtr::make(tkls->ptr(), elem, Type::Offset(0));
2494 } else if (klass->is_flat_array_klass() &&
2495 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) {
2496 ciKlass* elem = klass->as_flat_array_klass()->element_klass();
2497 return TypeInstKlassPtr::make(tkls->ptr(), elem, Type::Offset(0), /* flatten_array= */ true);
2498 }
2499 if( klass->is_instance_klass() && tkls->klass_is_exact() &&
2500 tkls->offset() == in_bytes(Klass::super_offset())) {
2501 ciKlass* sup = klass->as_instance_klass()->super();
2502 // The field is Klass::_super. Return its (constant) value.
2503 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
2504 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR;
2505 }
2506 }
2507
2508 // Bailout case
2509 return LoadNode::Value(phase);
2510 }
2511
2512 //------------------------------Identity---------------------------------------
2513 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
2514 // Also feed through the klass in Allocate(...klass...)._klass.
2515 Node* LoadKlassNode::Identity(PhaseGVN* phase) {
2516 return klass_identity_common(phase);
2517 }
2518
2519 Node* LoadNode::klass_identity_common(PhaseGVN* phase) {
2520 Node* x = LoadNode::Identity(phase);
2521 if (x != this) return x;
2522
2523 // Take apart the address into an oop and and offset.
2524 // Return 'this' if we cannot.
2525 Node* adr = in(MemNode::Address);
2526 intptr_t offset = 0;
2527 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2528 if (base == NULL) return this;
2529 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
2530 if (toop == NULL) return this;
2531
2532 // Step over potential GC barrier for OopHandle resolve
2533 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
2534 if (bs->is_gc_barrier_node(base)) {
2535 base = bs->step_over_gc_barrier(base);
2536 }
2537
2538 // We can fetch the klass directly through an AllocateNode.
2539 // This works even if the klass is not constant (clone or newArray).
2540 if (offset == oopDesc::klass_offset_in_bytes()) {
2541 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
2542 if (allocated_klass != NULL) {
2543 return allocated_klass;
2544 }
2545 }
2546
2547 // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*.
2548 // See inline_native_Class_query for occurrences of these patterns.
2549 // Java Example: x.getClass().isAssignableFrom(y)
2550 //
2551 // This improves reflective code, often making the Class
2552 // mirror go completely dead. (Current exception: Class
2553 // mirrors may appear in debug info, but we could clean them out by
2554 // introducing a new debug info operator for Klass.java_mirror).
2555
2556 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass()
2557 && offset == java_lang_Class::klass_offset()) {
2558 if (base->is_Load()) {
2559 Node* base2 = base->in(MemNode::Address);
2560 if (base2->is_Load()) { /* direct load of a load which is the OopHandle */
2561 Node* adr2 = base2->in(MemNode::Address);
2562 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2563 if (tkls != NULL && !tkls->empty()
2564 && (tkls->klass()->is_instance_klass() ||
2565 tkls->klass()->is_array_klass())
2566 && adr2->is_AddP()
2567 ) {
2568 int mirror_field = in_bytes(Klass::java_mirror_offset());
2569 if (tkls->offset() == mirror_field) {
2570 return adr2->in(AddPNode::Base);
2571 }
2572 }
2573 }
2574 }
2575 }
2576
2577 return this;
2578 }
2579
2580
2581 //------------------------------Value------------------------------------------
2582 const Type* LoadNKlassNode::Value(PhaseGVN* phase) const {
2583 const Type *t = klass_value_common(phase);
2584 if (t == Type::TOP)
2585 return t;
2586
2587 return t->make_narrowklass();
2588 }
2589
2590 //------------------------------Identity---------------------------------------
2591 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
2592 // Also feed through the klass in Allocate(...klass...)._klass.
2593 Node* LoadNKlassNode::Identity(PhaseGVN* phase) {
2594 Node *x = klass_identity_common(phase);
2595
2596 const Type *t = phase->type( x );
2597 if( t == Type::TOP ) return x;
2598 if( t->isa_narrowklass()) return x;
2599 assert (!t->isa_narrowoop(), "no narrow oop here");
2600
2601 return phase->transform(new EncodePKlassNode(x, t->make_narrowklass()));
2602 }
2603
2604 //------------------------------Value-----------------------------------------
2605 const Type* LoadRangeNode::Value(PhaseGVN* phase) const {
2606 // Either input is TOP ==> the result is TOP
2607 const Type *t1 = phase->type( in(MemNode::Memory) );
2608 if( t1 == Type::TOP ) return Type::TOP;
2609 Node *adr = in(MemNode::Address);
2610 const Type *t2 = phase->type( adr );
2611 if( t2 == Type::TOP ) return Type::TOP;
2612 const TypePtr *tp = t2->is_ptr();
2613 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
2614 const TypeAryPtr *tap = tp->isa_aryptr();
2615 if( !tap ) return _type;
2616 return tap->size();
2617 }
2618
2619 //-------------------------------Ideal---------------------------------------
2620 // Feed through the length in AllocateArray(...length...)._length.
2621 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2622 Node* p = MemNode::Ideal_common(phase, can_reshape);
2623 if (p) return (p == NodeSentinel) ? NULL : p;
2624
2625 // Take apart the address into an oop and and offset.
2626 // Return 'this' if we cannot.
2627 Node* adr = in(MemNode::Address);
2628 intptr_t offset = 0;
2629 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2630 if (base == NULL) return NULL;
2631 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2632 if (tary == NULL) return NULL;
2633
2634 // We can fetch the length directly through an AllocateArrayNode.
2635 // This works even if the length is not constant (clone or newArray).
2636 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2637 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2638 if (alloc != NULL) {
2639 Node* allocated_length = alloc->Ideal_length();
2640 Node* len = alloc->make_ideal_length(tary, phase);
2641 if (allocated_length != len) {
2642 // New CastII improves on this.
2643 return len;
2644 }
2645 }
2646 }
2647
2648 return NULL;
2649 }
2650
2651 //------------------------------Identity---------------------------------------
2652 // Feed through the length in AllocateArray(...length...)._length.
2653 Node* LoadRangeNode::Identity(PhaseGVN* phase) {
2654 Node* x = LoadINode::Identity(phase);
2655 if (x != this) return x;
2656
2657 // Take apart the address into an oop and and offset.
2658 // Return 'this' if we cannot.
2659 Node* adr = in(MemNode::Address);
2660 intptr_t offset = 0;
2661 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2662 if (base == NULL) return this;
2663 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2664 if (tary == NULL) return this;
2665
2666 // We can fetch the length directly through an AllocateArrayNode.
2667 // This works even if the length is not constant (clone or newArray).
2668 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2669 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2670 if (alloc != NULL) {
2671 Node* allocated_length = alloc->Ideal_length();
2672 // Do not allow make_ideal_length to allocate a CastII node.
2673 Node* len = alloc->make_ideal_length(tary, phase, false);
2674 if (allocated_length == len) {
2675 // Return allocated_length only if it would not be improved by a CastII.
2676 return allocated_length;
2677 }
2678 }
2679 }
2680
2681 return this;
2682
2683 }
2684
2685 //=============================================================================
2686 //---------------------------StoreNode::make-----------------------------------
2687 // Polymorphic factory method:
2688 StoreNode* StoreNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt, MemOrd mo) {
2689 assert((mo == unordered || mo == release), "unexpected");
2690 Compile* C = gvn.C;
2691 assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2692 ctl != NULL, "raw memory operations should have control edge");
2693
2694 switch (bt) {
2695 case T_BOOLEAN: val = gvn.transform(new AndINode(val, gvn.intcon(0x1))); // Fall through to T_BYTE case
2696 case T_BYTE: return new StoreBNode(ctl, mem, adr, adr_type, val, mo);
2697 case T_INT: return new StoreINode(ctl, mem, adr, adr_type, val, mo);
2698 case T_CHAR:
2699 case T_SHORT: return new StoreCNode(ctl, mem, adr, adr_type, val, mo);
2700 case T_LONG: return new StoreLNode(ctl, mem, adr, adr_type, val, mo);
2701 case T_FLOAT: return new StoreFNode(ctl, mem, adr, adr_type, val, mo);
2702 case T_DOUBLE: return new StoreDNode(ctl, mem, adr, adr_type, val, mo);
2703 case T_METADATA:
2704 case T_ADDRESS:
2705 case T_INLINE_TYPE:
2706 case T_OBJECT:
2707 #ifdef _LP64
2708 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
2709 val = gvn.transform(new EncodePNode(val, val->bottom_type()->make_narrowoop()));
2710 return new StoreNNode(ctl, mem, adr, adr_type, val, mo);
2711 } else if (adr->bottom_type()->is_ptr_to_narrowklass() ||
2712 (UseCompressedClassPointers && val->bottom_type()->isa_klassptr() &&
2713 adr->bottom_type()->isa_rawptr())) {
2714 val = gvn.transform(new EncodePKlassNode(val, val->bottom_type()->make_narrowklass()));
2715 return new StoreNKlassNode(ctl, mem, adr, adr_type, val, mo);
2716 }
2717 #endif
2718 {
2719 return new StorePNode(ctl, mem, adr, adr_type, val, mo);
2720 }
2721 default:
2722 ShouldNotReachHere();
2723 return (StoreNode*)NULL;
2724 }
2725 }
2726
2727 StoreLNode* StoreLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
2728 bool require_atomic = true;
2729 return new StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
2730 }
2731
2732 StoreDNode* StoreDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
2733 bool require_atomic = true;
2734 return new StoreDNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
2735 }
2736
2737
2738 //--------------------------bottom_type----------------------------------------
2739 const Type *StoreNode::bottom_type() const {
2740 return Type::MEMORY;
2741 }
2742
2743 //------------------------------hash-------------------------------------------
2744 uint StoreNode::hash() const {
2745 // unroll addition of interesting fields
2746 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2747
2748 // Since they are not commoned, do not hash them:
2749 return NO_HASH;
2750 }
2751
2752 //------------------------------Ideal------------------------------------------
2753 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
2754 // When a store immediately follows a relevant allocation/initialization,
2755 // try to capture it into the initialization, or hoist it above.
2756 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2757 Node* p = MemNode::Ideal_common(phase, can_reshape);
2758 if (p) return (p == NodeSentinel) ? NULL : p;
2759
2760 Node* mem = in(MemNode::Memory);
2761 Node* address = in(MemNode::Address);
2762 Node* value = in(MemNode::ValueIn);
2763 // Back-to-back stores to same address? Fold em up. Generally
2764 // unsafe if I have intervening uses... Also disallowed for StoreCM
2765 // since they must follow each StoreP operation. Redundant StoreCMs
2766 // are eliminated just before matching in final_graph_reshape.
2767 if (phase->C->get_adr_type(phase->C->get_alias_index(adr_type())) != TypeAryPtr::INLINES) {
2768 Node* st = mem;
2769 // If Store 'st' has more than one use, we cannot fold 'st' away.
2770 // For example, 'st' might be the final state at a conditional
2771 // return. Or, 'st' might be used by some node which is live at
2772 // the same time 'st' is live, which might be unschedulable. So,
2773 // require exactly ONE user until such time as we clone 'mem' for
2774 // each of 'mem's uses (thus making the exactly-1-user-rule hold
2775 // true).
2776 while (st->is_Store() && st->outcnt() == 1 && st->Opcode() != Op_StoreCM) {
2777 // Looking at a dead closed cycle of memory?
2778 assert(st != st->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
2779 assert(Opcode() == st->Opcode() ||
2780 st->Opcode() == Op_StoreVector ||
2781 Opcode() == Op_StoreVector ||
2782 st->Opcode() == Op_StoreVectorScatter ||
2783 Opcode() == Op_StoreVectorScatter ||
2784 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw ||
2785 (Opcode() == Op_StoreL && st->Opcode() == Op_StoreI) || // expanded ClearArrayNode
2786 (Opcode() == Op_StoreI && st->Opcode() == Op_StoreL) || // initialization by arraycopy
2787 (Opcode() == Op_StoreL && st->Opcode() == Op_StoreN) ||
2788 (is_mismatched_access() || st->as_Store()->is_mismatched_access()),
2789 "no mismatched stores, except on raw memory: %s %s", NodeClassNames[Opcode()], NodeClassNames[st->Opcode()]);
2790
2791 if (st->in(MemNode::Address)->eqv_uncast(address) &&
2792 st->as_Store()->memory_size() <= this->memory_size()) {
2793 Node* use = st->raw_out(0);
2794 if (phase->is_IterGVN()) {
2795 phase->is_IterGVN()->rehash_node_delayed(use);
2796 }
2797 // It's OK to do this in the parser, since DU info is always accurate,
2798 // and the parser always refers to nodes via SafePointNode maps.
2799 use->set_req_X(MemNode::Memory, st->in(MemNode::Memory), phase);
2800 return this;
2801 }
2802 st = st->in(MemNode::Memory);
2803 }
2804 }
2805
2806
2807 // Capture an unaliased, unconditional, simple store into an initializer.
2808 // Or, if it is independent of the allocation, hoist it above the allocation.
2809 if (ReduceFieldZeroing && /*can_reshape &&*/
2810 mem->is_Proj() && mem->in(0)->is_Initialize()) {
2811 InitializeNode* init = mem->in(0)->as_Initialize();
2812 intptr_t offset = init->can_capture_store(this, phase, can_reshape);
2813 if (offset > 0) {
2814 Node* moved = init->capture_store(this, offset, phase, can_reshape);
2815 // If the InitializeNode captured me, it made a raw copy of me,
2816 // and I need to disappear.
2817 if (moved != NULL) {
2818 // %%% hack to ensure that Ideal returns a new node:
2819 mem = MergeMemNode::make(mem);
2820 return mem; // fold me away
2821 }
2822 }
2823 }
2824
2825 // Fold reinterpret cast into memory operation:
2826 // StoreX mem (MoveY2X v) => StoreY mem v
2827 if (value->is_Move()) {
2828 const Type* vt = value->in(1)->bottom_type();
2829 if (has_reinterpret_variant(vt)) {
2830 if (phase->C->post_loop_opts_phase()) {
2831 return convert_to_reinterpret_store(*phase, value->in(1), vt);
2832 } else {
2833 phase->C->record_for_post_loop_opts_igvn(this); // attempt the transformation once loop opts are over
2834 }
2835 }
2836 }
2837
2838 return NULL; // No further progress
2839 }
2840
2841 //------------------------------Value-----------------------------------------
2842 const Type* StoreNode::Value(PhaseGVN* phase) const {
2843 // Either input is TOP ==> the result is TOP
2844 const Type *t1 = phase->type( in(MemNode::Memory) );
2845 if( t1 == Type::TOP ) return Type::TOP;
2846 const Type *t2 = phase->type( in(MemNode::Address) );
2847 if( t2 == Type::TOP ) return Type::TOP;
2848 const Type *t3 = phase->type( in(MemNode::ValueIn) );
2849 if( t3 == Type::TOP ) return Type::TOP;
2850 return Type::MEMORY;
2851 }
2852
2853 //------------------------------Identity---------------------------------------
2854 // Remove redundant stores:
2855 // Store(m, p, Load(m, p)) changes to m.
2856 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
2857 Node* StoreNode::Identity(PhaseGVN* phase) {
2858 Node* mem = in(MemNode::Memory);
2859 Node* adr = in(MemNode::Address);
2860 Node* val = in(MemNode::ValueIn);
2861
2862 Node* result = this;
2863
2864 // Load then Store? Then the Store is useless
2865 if (val->is_Load() &&
2866 val->in(MemNode::Address)->eqv_uncast(adr) &&
2867 val->in(MemNode::Memory )->eqv_uncast(mem) &&
2868 val->as_Load()->store_Opcode() == Opcode()) {
2869 result = mem;
2870 }
2871
2872 // Two stores in a row of the same value?
2873 if (result == this &&
2874 mem->is_Store() &&
2875 mem->in(MemNode::Address)->eqv_uncast(adr) &&
2876 mem->in(MemNode::ValueIn)->eqv_uncast(val) &&
2877 mem->Opcode() == Opcode()) {
2878 result = mem;
2879 }
2880
2881 // Store of zero anywhere into a freshly-allocated object?
2882 // Then the store is useless.
2883 // (It must already have been captured by the InitializeNode.)
2884 if (result == this && ReduceFieldZeroing) {
2885 // a newly allocated object is already all-zeroes everywhere
2886 if (mem->is_Proj() && mem->in(0)->is_Allocate() &&
2887 (phase->type(val)->is_zero_type() || mem->in(0)->in(AllocateNode::DefaultValue) == val)) {
2888 assert(!phase->type(val)->is_zero_type() || mem->in(0)->in(AllocateNode::DefaultValue) == NULL, "storing null to inline type array is forbidden");
2889 result = mem;
2890 }
2891
2892 if (result == this && phase->type(val)->is_zero_type()) {
2893 // the store may also apply to zero-bits in an earlier object
2894 Node* prev_mem = find_previous_store(phase);
2895 // Steps (a), (b): Walk past independent stores to find an exact match.
2896 if (prev_mem != NULL) {
2897 Node* prev_val = can_see_stored_value(prev_mem, phase);
2898 if (prev_val != NULL && prev_val == val) {
2899 // prev_val and val might differ by a cast; it would be good
2900 // to keep the more informative of the two.
2901 result = mem;
2902 }
2903 }
2904 }
2905 }
2906
2907 PhaseIterGVN* igvn = phase->is_IterGVN();
2908 if (result != this && igvn != NULL) {
2909 MemBarNode* trailing = trailing_membar();
2910 if (trailing != NULL) {
2911 #ifdef ASSERT
2912 const TypeOopPtr* t_oop = phase->type(in(Address))->isa_oopptr();
2913 assert(t_oop == NULL || t_oop->is_known_instance_field(), "only for non escaping objects");
2914 #endif
2915 trailing->remove(igvn);
2916 }
2917 }
2918
2919 return result;
2920 }
2921
2922 //------------------------------match_edge-------------------------------------
2923 // Do we Match on this edge index or not? Match only memory & value
2924 uint StoreNode::match_edge(uint idx) const {
2925 return idx == MemNode::Address || idx == MemNode::ValueIn;
2926 }
2927
2928 //------------------------------cmp--------------------------------------------
2929 // Do not common stores up together. They generally have to be split
2930 // back up anyways, so do not bother.
2931 bool StoreNode::cmp( const Node &n ) const {
2932 return (&n == this); // Always fail except on self
2933 }
2934
2935 //------------------------------Ideal_masked_input-----------------------------
2936 // Check for a useless mask before a partial-word store
2937 // (StoreB ... (AndI valIn conIa) )
2938 // If (conIa & mask == mask) this simplifies to
2939 // (StoreB ... (valIn) )
2940 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
2941 Node *val = in(MemNode::ValueIn);
2942 if( val->Opcode() == Op_AndI ) {
2943 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2944 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
2945 set_req_X(MemNode::ValueIn, val->in(1), phase);
2946 return this;
2947 }
2948 }
2949 return NULL;
2950 }
2951
2952
2953 //------------------------------Ideal_sign_extended_input----------------------
2954 // Check for useless sign-extension before a partial-word store
2955 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) )
2956 // If (conIL == conIR && conIR <= num_bits) this simplifies to
2957 // (StoreB ... (valIn) )
2958 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) {
2959 Node *val = in(MemNode::ValueIn);
2960 if( val->Opcode() == Op_RShiftI ) {
2961 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2962 if( t && t->is_con() && (t->get_con() <= num_bits) ) {
2963 Node *shl = val->in(1);
2964 if( shl->Opcode() == Op_LShiftI ) {
2965 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int();
2966 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) {
2967 set_req_X(MemNode::ValueIn, shl->in(1), phase);
2968 return this;
2969 }
2970 }
2971 }
2972 }
2973 return NULL;
2974 }
2975
2976 //------------------------------value_never_loaded-----------------------------------
2977 // Determine whether there are any possible loads of the value stored.
2978 // For simplicity, we actually check if there are any loads from the
2979 // address stored to, not just for loads of the value stored by this node.
2980 //
2981 bool StoreNode::value_never_loaded( PhaseTransform *phase) const {
2982 Node *adr = in(Address);
2983 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
2984 if (adr_oop == NULL)
2985 return false;
2986 if (!adr_oop->is_known_instance_field())
2987 return false; // if not a distinct instance, there may be aliases of the address
2988 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
2989 Node *use = adr->fast_out(i);
2990 if (use->is_Load() || use->is_LoadStore()) {
2991 return false;
2992 }
2993 }
2994 return true;
2995 }
2996
2997 MemBarNode* StoreNode::trailing_membar() const {
2998 if (is_release()) {
2999 MemBarNode* trailing_mb = NULL;
3000 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
3001 Node* u = fast_out(i);
3002 if (u->is_MemBar()) {
3003 if (u->as_MemBar()->trailing_store()) {
3004 assert(u->Opcode() == Op_MemBarVolatile, "");
3005 assert(trailing_mb == NULL, "only one");
3006 trailing_mb = u->as_MemBar();
3007 #ifdef ASSERT
3008 Node* leading = u->as_MemBar()->leading_membar();
3009 assert(leading->Opcode() == Op_MemBarRelease, "incorrect membar");
3010 assert(leading->as_MemBar()->leading_store(), "incorrect membar pair");
3011 assert(leading->as_MemBar()->trailing_membar() == u, "incorrect membar pair");
3012 #endif
3013 } else {
3014 assert(u->as_MemBar()->standalone(), "");
3015 }
3016 }
3017 }
3018 return trailing_mb;
3019 }
3020 return NULL;
3021 }
3022
3023
3024 //=============================================================================
3025 //------------------------------Ideal------------------------------------------
3026 // If the store is from an AND mask that leaves the low bits untouched, then
3027 // we can skip the AND operation. If the store is from a sign-extension
3028 // (a left shift, then right shift) we can skip both.
3029 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
3030 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
3031 if( progress != NULL ) return progress;
3032
3033 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
3034 if( progress != NULL ) return progress;
3035
3036 // Finally check the default case
3037 return StoreNode::Ideal(phase, can_reshape);
3038 }
3039
3040 //=============================================================================
3041 //------------------------------Ideal------------------------------------------
3042 // If the store is from an AND mask that leaves the low bits untouched, then
3043 // we can skip the AND operation
3044 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
3045 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
3046 if( progress != NULL ) return progress;
3047
3048 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
3049 if( progress != NULL ) return progress;
3050
3051 // Finally check the default case
3052 return StoreNode::Ideal(phase, can_reshape);
3053 }
3054
3055 //=============================================================================
3056 //------------------------------Identity---------------------------------------
3057 Node* StoreCMNode::Identity(PhaseGVN* phase) {
3058 // No need to card mark when storing a null ptr
3059 Node* my_store = in(MemNode::OopStore);
3060 if (my_store->is_Store()) {
3061 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) );
3062 if( t1 == TypePtr::NULL_PTR ) {
3063 return in(MemNode::Memory);
3064 }
3065 }
3066 return this;
3067 }
3068
3069 //=============================================================================
3070 //------------------------------Ideal---------------------------------------
3071 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){
3072 Node* progress = StoreNode::Ideal(phase, can_reshape);
3073 if (progress != NULL) return progress;
3074
3075 Node* my_store = in(MemNode::OopStore);
3076 if (my_store->is_MergeMem()) {
3077 if (oop_alias_idx() != phase->C->get_alias_index(TypeAryPtr::INLINES) ||
3078 phase->C->flattened_accesses_share_alias()) {
3079 // The alias that was recorded is no longer accurate enough.
3080 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx());
3081 set_req_X(MemNode::OopStore, mem, phase);
3082 return this;
3083 }
3084 }
3085
3086 return NULL;
3087 }
3088
3089 //------------------------------Value-----------------------------------------
3090 const Type* StoreCMNode::Value(PhaseGVN* phase) const {
3091 // Either input is TOP ==> the result is TOP (checked in StoreNode::Value).
3092 // If extra input is TOP ==> the result is TOP
3093 const Type* t = phase->type(in(MemNode::OopStore));
3094 if (t == Type::TOP) {
3095 return Type::TOP;
3096 }
3097 return StoreNode::Value(phase);
3098 }
3099
3100
3101 //=============================================================================
3102 //----------------------------------SCMemProjNode------------------------------
3103 const Type* SCMemProjNode::Value(PhaseGVN* phase) const
3104 {
3105 if (in(0) == NULL || phase->type(in(0)) == Type::TOP) {
3106 return Type::TOP;
3107 }
3108 return bottom_type();
3109 }
3110
3111 //=============================================================================
3112 //----------------------------------LoadStoreNode------------------------------
3113 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required )
3114 : Node(required),
3115 _type(rt),
3116 _adr_type(at),
3117 _barrier_data(0)
3118 {
3119 init_req(MemNode::Control, c );
3120 init_req(MemNode::Memory , mem);
3121 init_req(MemNode::Address, adr);
3122 init_req(MemNode::ValueIn, val);
3123 init_class_id(Class_LoadStore);
3124 }
3125
3126 //------------------------------Value-----------------------------------------
3127 const Type* LoadStoreNode::Value(PhaseGVN* phase) const {
3128 // Either input is TOP ==> the result is TOP
3129 if (!in(MemNode::Control) || phase->type(in(MemNode::Control)) == Type::TOP) {
3130 return Type::TOP;
3131 }
3132 const Type* t = phase->type(in(MemNode::Memory));
3133 if (t == Type::TOP) {
3134 return Type::TOP;
3135 }
3136 t = phase->type(in(MemNode::Address));
3137 if (t == Type::TOP) {
3138 return Type::TOP;
3139 }
3140 t = phase->type(in(MemNode::ValueIn));
3141 if (t == Type::TOP) {
3142 return Type::TOP;
3143 }
3144 return bottom_type();
3145 }
3146
3147 uint LoadStoreNode::ideal_reg() const {
3148 return _type->ideal_reg();
3149 }
3150
3151 bool LoadStoreNode::result_not_used() const {
3152 for( DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++ ) {
3153 Node *x = fast_out(i);
3154 if (x->Opcode() == Op_SCMemProj) continue;
3155 return false;
3156 }
3157 return true;
3158 }
3159
3160 MemBarNode* LoadStoreNode::trailing_membar() const {
3161 MemBarNode* trailing = NULL;
3162 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
3163 Node* u = fast_out(i);
3164 if (u->is_MemBar()) {
3165 if (u->as_MemBar()->trailing_load_store()) {
3166 assert(u->Opcode() == Op_MemBarAcquire, "");
3167 assert(trailing == NULL, "only one");
3168 trailing = u->as_MemBar();
3169 #ifdef ASSERT
3170 Node* leading = trailing->leading_membar();
3171 assert(support_IRIW_for_not_multiple_copy_atomic_cpu || leading->Opcode() == Op_MemBarRelease, "incorrect membar");
3172 assert(leading->as_MemBar()->leading_load_store(), "incorrect membar pair");
3173 assert(leading->as_MemBar()->trailing_membar() == trailing, "incorrect membar pair");
3174 #endif
3175 } else {
3176 assert(u->as_MemBar()->standalone(), "wrong barrier kind");
3177 }
3178 }
3179 }
3180
3181 return trailing;
3182 }
3183
3184 uint LoadStoreNode::size_of() const { return sizeof(*this); }
3185
3186 //=============================================================================
3187 //----------------------------------LoadStoreConditionalNode--------------------
3188 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, NULL, TypeInt::BOOL, 5) {
3189 init_req(ExpectedIn, ex );
3190 }
3191
3192 const Type* LoadStoreConditionalNode::Value(PhaseGVN* phase) const {
3193 // Either input is TOP ==> the result is TOP
3194 const Type* t = phase->type(in(ExpectedIn));
3195 if (t == Type::TOP) {
3196 return Type::TOP;
3197 }
3198 return LoadStoreNode::Value(phase);
3199 }
3200
3201 //=============================================================================
3202 //-------------------------------adr_type--------------------------------------
3203 const TypePtr* ClearArrayNode::adr_type() const {
3204 Node *adr = in(3);
3205 if (adr == NULL) return NULL; // node is dead
3206 return MemNode::calculate_adr_type(adr->bottom_type());
3207 }
3208
3209 //------------------------------match_edge-------------------------------------
3210 // Do we Match on this edge index or not? Do not match memory
3211 uint ClearArrayNode::match_edge(uint idx) const {
3212 return idx > 1;
3213 }
3214
3215 //------------------------------Identity---------------------------------------
3216 // Clearing a zero length array does nothing
3217 Node* ClearArrayNode::Identity(PhaseGVN* phase) {
3218 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
3219 }
3220
3221 //------------------------------Idealize---------------------------------------
3222 // Clearing a short array is faster with stores
3223 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3224 // Already know this is a large node, do not try to ideal it
3225 if (!IdealizeClearArrayNode || _is_large) return NULL;
3226
3227 const int unit = BytesPerLong;
3228 const TypeX* t = phase->type(in(2))->isa_intptr_t();
3229 if (!t) return NULL;
3230 if (!t->is_con()) return NULL;
3231 intptr_t raw_count = t->get_con();
3232 intptr_t size = raw_count;
3233 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
3234 // Clearing nothing uses the Identity call.
3235 // Negative clears are possible on dead ClearArrays
3236 // (see jck test stmt114.stmt11402.val).
3237 if (size <= 0 || size % unit != 0) return NULL;
3238 intptr_t count = size / unit;
3239 // Length too long; communicate this to matchers and assemblers.
3240 // Assemblers are responsible to produce fast hardware clears for it.
3241 if (size > InitArrayShortSize) {
3242 return new ClearArrayNode(in(0), in(1), in(2), in(3), in(4), true);
3243 } else if (size > 2 && Matcher::match_rule_supported_vector(Op_ClearArray, 4, T_LONG)) {
3244 return NULL;
3245 }
3246 Node *mem = in(1);
3247 if( phase->type(mem)==Type::TOP ) return NULL;
3248 Node *adr = in(3);
3249 const Type* at = phase->type(adr);
3250 if( at==Type::TOP ) return NULL;
3251 const TypePtr* atp = at->isa_ptr();
3252 // adjust atp to be the correct array element address type
3253 if (atp == NULL) atp = TypePtr::BOTTOM;
3254 else atp = atp->add_offset(Type::OffsetBot);
3255 // Get base for derived pointer purposes
3256 if( adr->Opcode() != Op_AddP ) Unimplemented();
3257 Node *base = adr->in(1);
3258
3259 Node *val = in(4);
3260 Node *off = phase->MakeConX(BytesPerLong);
3261 mem = new StoreLNode(in(0), mem, adr, atp, val, MemNode::unordered, false);
3262 count--;
3263 while( count-- ) {
3264 mem = phase->transform(mem);
3265 adr = phase->transform(new AddPNode(base,adr,off));
3266 mem = new StoreLNode(in(0), mem, adr, atp, val, MemNode::unordered, false);
3267 }
3268 return mem;
3269 }
3270
3271 //----------------------------step_through----------------------------------
3272 // Return allocation input memory edge if it is different instance
3273 // or itself if it is the one we are looking for.
3274 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) {
3275 Node* n = *np;
3276 assert(n->is_ClearArray(), "sanity");
3277 intptr_t offset;
3278 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
3279 // This method is called only before Allocate nodes are expanded
3280 // during macro nodes expansion. Before that ClearArray nodes are
3281 // only generated in PhaseMacroExpand::generate_arraycopy() (before
3282 // Allocate nodes are expanded) which follows allocations.
3283 assert(alloc != NULL, "should have allocation");
3284 if (alloc->_idx == instance_id) {
3285 // Can not bypass initialization of the instance we are looking for.
3286 return false;
3287 }
3288 // Otherwise skip it.
3289 InitializeNode* init = alloc->initialization();
3290 if (init != NULL)
3291 *np = init->in(TypeFunc::Memory);
3292 else
3293 *np = alloc->in(TypeFunc::Memory);
3294 return true;
3295 }
3296
3297 //----------------------------clear_memory-------------------------------------
3298 // Generate code to initialize object storage to zero.
3299 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
3300 Node* val,
3301 Node* raw_val,
3302 intptr_t start_offset,
3303 Node* end_offset,
3304 PhaseGVN* phase) {
3305 intptr_t offset = start_offset;
3306
3307 int unit = BytesPerLong;
3308 if ((offset % unit) != 0) {
3309 Node* adr = new AddPNode(dest, dest, phase->MakeConX(offset));
3310 adr = phase->transform(adr);
3311 const TypePtr* atp = TypeRawPtr::BOTTOM;
3312 if (val != NULL) {
3313 assert(phase->type(val)->isa_narrowoop(), "should be narrow oop");
3314 mem = new StoreNNode(ctl, mem, adr, atp, val, MemNode::unordered);
3315 } else {
3316 assert(raw_val == NULL, "val may not be null");
3317 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
3318 }
3319 mem = phase->transform(mem);
3320 offset += BytesPerInt;
3321 }
3322 assert((offset % unit) == 0, "");
3323
3324 // Initialize the remaining stuff, if any, with a ClearArray.
3325 return clear_memory(ctl, mem, dest, raw_val, phase->MakeConX(offset), end_offset, phase);
3326 }
3327
3328 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
3329 Node* raw_val,
3330 Node* start_offset,
3331 Node* end_offset,
3332 PhaseGVN* phase) {
3333 if (start_offset == end_offset) {
3334 // nothing to do
3335 return mem;
3336 }
3337
3338 int unit = BytesPerLong;
3339 Node* zbase = start_offset;
3340 Node* zend = end_offset;
3341
3342 // Scale to the unit required by the CPU:
3343 if (!Matcher::init_array_count_is_in_bytes) {
3344 Node* shift = phase->intcon(exact_log2(unit));
3345 zbase = phase->transform(new URShiftXNode(zbase, shift) );
3346 zend = phase->transform(new URShiftXNode(zend, shift) );
3347 }
3348
3349 // Bulk clear double-words
3350 Node* zsize = phase->transform(new SubXNode(zend, zbase) );
3351 Node* adr = phase->transform(new AddPNode(dest, dest, start_offset) );
3352 if (raw_val == NULL) {
3353 raw_val = phase->MakeConX(0);
3354 }
3355 mem = new ClearArrayNode(ctl, mem, zsize, adr, raw_val, false);
3356 return phase->transform(mem);
3357 }
3358
3359 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
3360 Node* val,
3361 Node* raw_val,
3362 intptr_t start_offset,
3363 intptr_t end_offset,
3364 PhaseGVN* phase) {
3365 if (start_offset == end_offset) {
3366 // nothing to do
3367 return mem;
3368 }
3369
3370 assert((end_offset % BytesPerInt) == 0, "odd end offset");
3371 intptr_t done_offset = end_offset;
3372 if ((done_offset % BytesPerLong) != 0) {
3373 done_offset -= BytesPerInt;
3374 }
3375 if (done_offset > start_offset) {
3376 mem = clear_memory(ctl, mem, dest, val, raw_val,
3377 start_offset, phase->MakeConX(done_offset), phase);
3378 }
3379 if (done_offset < end_offset) { // emit the final 32-bit store
3380 Node* adr = new AddPNode(dest, dest, phase->MakeConX(done_offset));
3381 adr = phase->transform(adr);
3382 const TypePtr* atp = TypeRawPtr::BOTTOM;
3383 if (val != NULL) {
3384 assert(phase->type(val)->isa_narrowoop(), "should be narrow oop");
3385 mem = new StoreNNode(ctl, mem, adr, atp, val, MemNode::unordered);
3386 } else {
3387 assert(raw_val == NULL, "val may not be null");
3388 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
3389 }
3390 mem = phase->transform(mem);
3391 done_offset += BytesPerInt;
3392 }
3393 assert(done_offset == end_offset, "");
3394 return mem;
3395 }
3396
3397 //=============================================================================
3398 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
3399 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)),
3400 _adr_type(C->get_adr_type(alias_idx)), _kind(Standalone)
3401 #ifdef ASSERT
3402 , _pair_idx(0)
3403 #endif
3404 {
3405 init_class_id(Class_MemBar);
3406 Node* top = C->top();
3407 init_req(TypeFunc::I_O,top);
3408 init_req(TypeFunc::FramePtr,top);
3409 init_req(TypeFunc::ReturnAdr,top);
3410 if (precedent != NULL)
3411 init_req(TypeFunc::Parms, precedent);
3412 }
3413
3414 //------------------------------cmp--------------------------------------------
3415 uint MemBarNode::hash() const { return NO_HASH; }
3416 bool MemBarNode::cmp( const Node &n ) const {
3417 return (&n == this); // Always fail except on self
3418 }
3419
3420 //------------------------------make-------------------------------------------
3421 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
3422 switch (opcode) {
3423 case Op_MemBarAcquire: return new MemBarAcquireNode(C, atp, pn);
3424 case Op_LoadFence: return new LoadFenceNode(C, atp, pn);
3425 case Op_MemBarRelease: return new MemBarReleaseNode(C, atp, pn);
3426 case Op_StoreFence: return new StoreFenceNode(C, atp, pn);
3427 case Op_MemBarAcquireLock: return new MemBarAcquireLockNode(C, atp, pn);
3428 case Op_MemBarReleaseLock: return new MemBarReleaseLockNode(C, atp, pn);
3429 case Op_MemBarVolatile: return new MemBarVolatileNode(C, atp, pn);
3430 case Op_MemBarCPUOrder: return new MemBarCPUOrderNode(C, atp, pn);
3431 case Op_OnSpinWait: return new OnSpinWaitNode(C, atp, pn);
3432 case Op_Initialize: return new InitializeNode(C, atp, pn);
3433 case Op_MemBarStoreStore: return new MemBarStoreStoreNode(C, atp, pn);
3434 case Op_Blackhole: return new BlackholeNode(C, atp, pn);
3435 default: ShouldNotReachHere(); return NULL;
3436 }
3437 }
3438
3439 void MemBarNode::remove(PhaseIterGVN *igvn) {
3440 if (outcnt() != 2) {
3441 assert(Opcode() == Op_Initialize, "Only seen when there are no use of init memory");
3442 assert(outcnt() == 1, "Only control then");
3443 }
3444 if (trailing_store() || trailing_load_store()) {
3445 MemBarNode* leading = leading_membar();
3446 if (leading != NULL) {
3447 assert(leading->trailing_membar() == this, "inconsistent leading/trailing membars");
3448 leading->remove(igvn);
3449 }
3450 }
3451 if (proj_out_or_null(TypeFunc::Memory) != NULL) {
3452 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
3453 }
3454 if (proj_out_or_null(TypeFunc::Control) != NULL) {
3455 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
3456 }
3457 }
3458
3459 //------------------------------Ideal------------------------------------------
3460 // Return a node which is more "ideal" than the current node. Strip out
3461 // control copies
3462 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3463 if (remove_dead_region(phase, can_reshape)) return this;
3464 // Don't bother trying to transform a dead node
3465 if (in(0) && in(0)->is_top()) {
3466 return NULL;
3467 }
3468
3469 bool progress = false;
3470 // Eliminate volatile MemBars for scalar replaced objects.
3471 if (can_reshape && req() == (Precedent+1)) {
3472 bool eliminate = false;
3473 int opc = Opcode();
3474 if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) {
3475 // Volatile field loads and stores.
3476 Node* my_mem = in(MemBarNode::Precedent);
3477 // The MembarAquire may keep an unused LoadNode alive through the Precedent edge
3478 if ((my_mem != NULL) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) {
3479 // if the Precedent is a decodeN and its input (a Load) is used at more than one place,
3480 // replace this Precedent (decodeN) with the Load instead.
3481 if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1)) {
3482 Node* load_node = my_mem->in(1);
3483 set_req(MemBarNode::Precedent, load_node);
3484 phase->is_IterGVN()->_worklist.push(my_mem);
3485 my_mem = load_node;
3486 } else {
3487 assert(my_mem->unique_out() == this, "sanity");
3488 del_req(Precedent);
3489 phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later
3490 my_mem = NULL;
3491 }
3492 progress = true;
3493 }
3494 if (my_mem != NULL && my_mem->is_Mem()) {
3495 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
3496 // Check for scalar replaced object reference.
3497 if( t_oop != NULL && t_oop->is_known_instance_field() &&
3498 t_oop->offset() != Type::OffsetBot &&
3499 t_oop->offset() != Type::OffsetTop) {
3500 eliminate = true;
3501 }
3502 }
3503 } else if (opc == Op_MemBarRelease) {
3504 // Final field stores.
3505 Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent), phase);
3506 if ((alloc != NULL) && alloc->is_Allocate() &&
3507 alloc->as_Allocate()->does_not_escape_thread()) {
3508 // The allocated object does not escape.
3509 eliminate = true;
3510 }
3511 }
3512 if (eliminate) {
3513 // Replace MemBar projections by its inputs.
3514 PhaseIterGVN* igvn = phase->is_IterGVN();
3515 remove(igvn);
3516 // Must return either the original node (now dead) or a new node
3517 // (Do not return a top here, since that would break the uniqueness of top.)
3518 return new ConINode(TypeInt::ZERO);
3519 }
3520 }
3521 return progress ? this : NULL;
3522 }
3523
3524 //------------------------------Value------------------------------------------
3525 const Type* MemBarNode::Value(PhaseGVN* phase) const {
3526 if( !in(0) ) return Type::TOP;
3527 if( phase->type(in(0)) == Type::TOP )
3528 return Type::TOP;
3529 return TypeTuple::MEMBAR;
3530 }
3531
3532 //------------------------------match------------------------------------------
3533 // Construct projections for memory.
3534 Node *MemBarNode::match(const ProjNode *proj, const Matcher *m, const RegMask* mask) {
3535 switch (proj->_con) {
3536 case TypeFunc::Control:
3537 case TypeFunc::Memory:
3538 return new MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
3539 }
3540 ShouldNotReachHere();
3541 return NULL;
3542 }
3543
3544 void MemBarNode::set_store_pair(MemBarNode* leading, MemBarNode* trailing) {
3545 trailing->_kind = TrailingStore;
3546 leading->_kind = LeadingStore;
3547 #ifdef ASSERT
3548 trailing->_pair_idx = leading->_idx;
3549 leading->_pair_idx = leading->_idx;
3550 #endif
3551 }
3552
3553 void MemBarNode::set_load_store_pair(MemBarNode* leading, MemBarNode* trailing) {
3554 trailing->_kind = TrailingLoadStore;
3555 leading->_kind = LeadingLoadStore;
3556 #ifdef ASSERT
3557 trailing->_pair_idx = leading->_idx;
3558 leading->_pair_idx = leading->_idx;
3559 #endif
3560 }
3561
3562 MemBarNode* MemBarNode::trailing_membar() const {
3563 ResourceMark rm;
3564 Node* trailing = (Node*)this;
3565 VectorSet seen;
3566 Node_Stack multis(0);
3567 do {
3568 Node* c = trailing;
3569 uint i = 0;
3570 do {
3571 trailing = NULL;
3572 for (; i < c->outcnt(); i++) {
3573 Node* next = c->raw_out(i);
3574 if (next != c && next->is_CFG()) {
3575 if (c->is_MultiBranch()) {
3576 if (multis.node() == c) {
3577 multis.set_index(i+1);
3578 } else {
3579 multis.push(c, i+1);
3580 }
3581 }
3582 trailing = next;
3583 break;
3584 }
3585 }
3586 if (trailing != NULL && !seen.test_set(trailing->_idx)) {
3587 break;
3588 }
3589 while (multis.size() > 0) {
3590 c = multis.node();
3591 i = multis.index();
3592 if (i < c->req()) {
3593 break;
3594 }
3595 multis.pop();
3596 }
3597 } while (multis.size() > 0);
3598 } while (!trailing->is_MemBar() || !trailing->as_MemBar()->trailing());
3599
3600 MemBarNode* mb = trailing->as_MemBar();
3601 assert((mb->_kind == TrailingStore && _kind == LeadingStore) ||
3602 (mb->_kind == TrailingLoadStore && _kind == LeadingLoadStore), "bad trailing membar");
3603 assert(mb->_pair_idx == _pair_idx, "bad trailing membar");
3604 return mb;
3605 }
3606
3607 MemBarNode* MemBarNode::leading_membar() const {
3608 ResourceMark rm;
3609 VectorSet seen;
3610 Node_Stack regions(0);
3611 Node* leading = in(0);
3612 while (leading != NULL && (!leading->is_MemBar() || !leading->as_MemBar()->leading())) {
3613 while (leading == NULL || leading->is_top() || seen.test_set(leading->_idx)) {
3614 leading = NULL;
3615 while (regions.size() > 0 && leading == NULL) {
3616 Node* r = regions.node();
3617 uint i = regions.index();
3618 if (i < r->req()) {
3619 leading = r->in(i);
3620 regions.set_index(i+1);
3621 } else {
3622 regions.pop();
3623 }
3624 }
3625 if (leading == NULL) {
3626 assert(regions.size() == 0, "all paths should have been tried");
3627 return NULL;
3628 }
3629 }
3630 if (leading->is_Region()) {
3631 regions.push(leading, 2);
3632 leading = leading->in(1);
3633 } else {
3634 leading = leading->in(0);
3635 }
3636 }
3637 #ifdef ASSERT
3638 Unique_Node_List wq;
3639 wq.push((Node*)this);
3640 uint found = 0;
3641 for (uint i = 0; i < wq.size(); i++) {
3642 Node* n = wq.at(i);
3643 if (n->is_Region()) {
3644 for (uint j = 1; j < n->req(); j++) {
3645 Node* in = n->in(j);
3646 if (in != NULL && !in->is_top()) {
3647 wq.push(in);
3648 }
3649 }
3650 } else {
3651 if (n->is_MemBar() && n->as_MemBar()->leading()) {
3652 assert(n == leading, "consistency check failed");
3653 found++;
3654 } else {
3655 Node* in = n->in(0);
3656 if (in != NULL && !in->is_top()) {
3657 wq.push(in);
3658 }
3659 }
3660 }
3661 }
3662 assert(found == 1 || (found == 0 && leading == NULL), "consistency check failed");
3663 #endif
3664 if (leading == NULL) {
3665 return NULL;
3666 }
3667 MemBarNode* mb = leading->as_MemBar();
3668 assert((mb->_kind == LeadingStore && _kind == TrailingStore) ||
3669 (mb->_kind == LeadingLoadStore && _kind == TrailingLoadStore), "bad leading membar");
3670 assert(mb->_pair_idx == _pair_idx, "bad leading membar");
3671 return mb;
3672 }
3673
3674 #ifndef PRODUCT
3675 void BlackholeNode::format(PhaseRegAlloc* ra, outputStream* st) const {
3676 st->print("blackhole ");
3677 bool first = true;
3678 for (uint i = 0; i < req(); i++) {
3679 Node* n = in(i);
3680 if (n != NULL && OptoReg::is_valid(ra->get_reg_first(n))) {
3681 if (first) {
3682 first = false;
3683 } else {
3684 st->print(", ");
3685 }
3686 char buf[128];
3687 ra->dump_register(n, buf);
3688 st->print("%s", buf);
3689 }
3690 }
3691 st->cr();
3692 }
3693 #endif
3694
3695 //===========================InitializeNode====================================
3696 // SUMMARY:
3697 // This node acts as a memory barrier on raw memory, after some raw stores.
3698 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
3699 // The Initialize can 'capture' suitably constrained stores as raw inits.
3700 // It can coalesce related raw stores into larger units (called 'tiles').
3701 // It can avoid zeroing new storage for memory units which have raw inits.
3702 // At macro-expansion, it is marked 'complete', and does not optimize further.
3703 //
3704 // EXAMPLE:
3705 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
3706 // ctl = incoming control; mem* = incoming memory
3707 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
3708 // First allocate uninitialized memory and fill in the header:
3709 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
3710 // ctl := alloc.Control; mem* := alloc.Memory*
3711 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
3712 // Then initialize to zero the non-header parts of the raw memory block:
3713 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
3714 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
3715 // After the initialize node executes, the object is ready for service:
3716 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
3717 // Suppose its body is immediately initialized as {1,2}:
3718 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3719 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3720 // mem.SLICE(#short[*]) := store2
3721 //
3722 // DETAILS:
3723 // An InitializeNode collects and isolates object initialization after
3724 // an AllocateNode and before the next possible safepoint. As a
3725 // memory barrier (MemBarNode), it keeps critical stores from drifting
3726 // down past any safepoint or any publication of the allocation.
3727 // Before this barrier, a newly-allocated object may have uninitialized bits.
3728 // After this barrier, it may be treated as a real oop, and GC is allowed.
3729 //
3730 // The semantics of the InitializeNode include an implicit zeroing of
3731 // the new object from object header to the end of the object.
3732 // (The object header and end are determined by the AllocateNode.)
3733 //
3734 // Certain stores may be added as direct inputs to the InitializeNode.
3735 // These stores must update raw memory, and they must be to addresses
3736 // derived from the raw address produced by AllocateNode, and with
3737 // a constant offset. They must be ordered by increasing offset.
3738 // The first one is at in(RawStores), the last at in(req()-1).
3739 // Unlike most memory operations, they are not linked in a chain,
3740 // but are displayed in parallel as users of the rawmem output of
3741 // the allocation.
3742 //
3743 // (See comments in InitializeNode::capture_store, which continue
3744 // the example given above.)
3745 //
3746 // When the associated Allocate is macro-expanded, the InitializeNode
3747 // may be rewritten to optimize collected stores. A ClearArrayNode
3748 // may also be created at that point to represent any required zeroing.
3749 // The InitializeNode is then marked 'complete', prohibiting further
3750 // capturing of nearby memory operations.
3751 //
3752 // During macro-expansion, all captured initializations which store
3753 // constant values of 32 bits or smaller are coalesced (if advantageous)
3754 // into larger 'tiles' 32 or 64 bits. This allows an object to be
3755 // initialized in fewer memory operations. Memory words which are
3756 // covered by neither tiles nor non-constant stores are pre-zeroed
3757 // by explicit stores of zero. (The code shape happens to do all
3758 // zeroing first, then all other stores, with both sequences occurring
3759 // in order of ascending offsets.)
3760 //
3761 // Alternatively, code may be inserted between an AllocateNode and its
3762 // InitializeNode, to perform arbitrary initialization of the new object.
3763 // E.g., the object copying intrinsics insert complex data transfers here.
3764 // The initialization must then be marked as 'complete' disable the
3765 // built-in zeroing semantics and the collection of initializing stores.
3766 //
3767 // While an InitializeNode is incomplete, reads from the memory state
3768 // produced by it are optimizable if they match the control edge and
3769 // new oop address associated with the allocation/initialization.
3770 // They return a stored value (if the offset matches) or else zero.
3771 // A write to the memory state, if it matches control and address,
3772 // and if it is to a constant offset, may be 'captured' by the
3773 // InitializeNode. It is cloned as a raw memory operation and rewired
3774 // inside the initialization, to the raw oop produced by the allocation.
3775 // Operations on addresses which are provably distinct (e.g., to
3776 // other AllocateNodes) are allowed to bypass the initialization.
3777 //
3778 // The effect of all this is to consolidate object initialization
3779 // (both arrays and non-arrays, both piecewise and bulk) into a
3780 // single location, where it can be optimized as a unit.
3781 //
3782 // Only stores with an offset less than TrackedInitializationLimit words
3783 // will be considered for capture by an InitializeNode. This puts a
3784 // reasonable limit on the complexity of optimized initializations.
3785
3786 //---------------------------InitializeNode------------------------------------
3787 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
3788 : MemBarNode(C, adr_type, rawoop),
3789 _is_complete(Incomplete), _does_not_escape(false)
3790 {
3791 init_class_id(Class_Initialize);
3792
3793 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
3794 assert(in(RawAddress) == rawoop, "proper init");
3795 // Note: allocation() can be NULL, for secondary initialization barriers
3796 }
3797
3798 // Since this node is not matched, it will be processed by the
3799 // register allocator. Declare that there are no constraints
3800 // on the allocation of the RawAddress edge.
3801 const RegMask &InitializeNode::in_RegMask(uint idx) const {
3802 // This edge should be set to top, by the set_complete. But be conservative.
3803 if (idx == InitializeNode::RawAddress)
3804 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
3805 return RegMask::Empty;
3806 }
3807
3808 Node* InitializeNode::memory(uint alias_idx) {
3809 Node* mem = in(Memory);
3810 if (mem->is_MergeMem()) {
3811 return mem->as_MergeMem()->memory_at(alias_idx);
3812 } else {
3813 // incoming raw memory is not split
3814 return mem;
3815 }
3816 }
3817
3818 bool InitializeNode::is_non_zero() {
3819 if (is_complete()) return false;
3820 remove_extra_zeroes();
3821 return (req() > RawStores);
3822 }
3823
3824 void InitializeNode::set_complete(PhaseGVN* phase) {
3825 assert(!is_complete(), "caller responsibility");
3826 _is_complete = Complete;
3827
3828 // After this node is complete, it contains a bunch of
3829 // raw-memory initializations. There is no need for
3830 // it to have anything to do with non-raw memory effects.
3831 // Therefore, tell all non-raw users to re-optimize themselves,
3832 // after skipping the memory effects of this initialization.
3833 PhaseIterGVN* igvn = phase->is_IterGVN();
3834 if (igvn) igvn->add_users_to_worklist(this);
3835 }
3836
3837 // convenience function
3838 // return false if the init contains any stores already
3839 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
3840 InitializeNode* init = initialization();
3841 if (init == NULL || init->is_complete()) {
3842 return false;
3843 }
3844 init->remove_extra_zeroes();
3845 // for now, if this allocation has already collected any inits, bail:
3846 if (init->is_non_zero()) return false;
3847 init->set_complete(phase);
3848 return true;
3849 }
3850
3851 void InitializeNode::remove_extra_zeroes() {
3852 if (req() == RawStores) return;
3853 Node* zmem = zero_memory();
3854 uint fill = RawStores;
3855 for (uint i = fill; i < req(); i++) {
3856 Node* n = in(i);
3857 if (n->is_top() || n == zmem) continue; // skip
3858 if (fill < i) set_req(fill, n); // compact
3859 ++fill;
3860 }
3861 // delete any empty spaces created:
3862 while (fill < req()) {
3863 del_req(fill);
3864 }
3865 }
3866
3867 // Helper for remembering which stores go with which offsets.
3868 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) {
3869 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
3870 intptr_t offset = -1;
3871 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
3872 phase, offset);
3873 if (base == NULL) return -1; // something is dead,
3874 if (offset < 0) return -1; // dead, dead
3875 return offset;
3876 }
3877
3878 // Helper for proving that an initialization expression is
3879 // "simple enough" to be folded into an object initialization.
3880 // Attempts to prove that a store's initial value 'n' can be captured
3881 // within the initialization without creating a vicious cycle, such as:
3882 // { Foo p = new Foo(); p.next = p; }
3883 // True for constants and parameters and small combinations thereof.
3884 bool InitializeNode::detect_init_independence(Node* value, PhaseGVN* phase) {
3885 ResourceMark rm;
3886 Unique_Node_List worklist;
3887 worklist.push(value);
3888
3889 uint complexity_limit = 20;
3890 for (uint j = 0; j < worklist.size(); j++) {
3891 if (j >= complexity_limit) {
3892 return false; // Bail out if processed too many nodes
3893 }
3894
3895 Node* n = worklist.at(j);
3896 if (n == NULL) continue; // (can this really happen?)
3897 if (n->is_Proj()) n = n->in(0);
3898 if (n == this) return false; // found a cycle
3899 if (n->is_Con()) continue;
3900 if (n->is_Start()) continue; // params, etc., are OK
3901 if (n->is_Root()) continue; // even better
3902
3903 // There cannot be any dependency if 'n' is a CFG node that dominates the current allocation
3904 if (n->is_CFG() && phase->is_dominator(n, allocation())) {
3905 continue;
3906 }
3907
3908 Node* ctl = n->in(0);
3909 if (ctl != NULL && !ctl->is_top()) {
3910 if (ctl->is_Proj()) ctl = ctl->in(0);
3911 if (ctl == this) return false;
3912
3913 // If we already know that the enclosing memory op is pinned right after
3914 // the init, then any control flow that the store has picked up
3915 // must have preceded the init, or else be equal to the init.
3916 // Even after loop optimizations (which might change control edges)
3917 // a store is never pinned *before* the availability of its inputs.
3918 if (!MemNode::all_controls_dominate(n, this))
3919 return false; // failed to prove a good control
3920 }
3921
3922 // Check data edges for possible dependencies on 'this'.
3923 for (uint i = 1; i < n->req(); i++) {
3924 Node* m = n->in(i);
3925 if (m == NULL || m == n || m->is_top()) continue;
3926
3927 // Only process data inputs once
3928 worklist.push(m);
3929 }
3930 }
3931
3932 return true;
3933 }
3934
3935 // Here are all the checks a Store must pass before it can be moved into
3936 // an initialization. Returns zero if a check fails.
3937 // On success, returns the (constant) offset to which the store applies,
3938 // within the initialized memory.
3939 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseGVN* phase, bool can_reshape) {
3940 const int FAIL = 0;
3941 if (st->req() != MemNode::ValueIn + 1)
3942 return FAIL; // an inscrutable StoreNode (card mark?)
3943 Node* ctl = st->in(MemNode::Control);
3944 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this))
3945 return FAIL; // must be unconditional after the initialization
3946 Node* mem = st->in(MemNode::Memory);
3947 if (!(mem->is_Proj() && mem->in(0) == this))
3948 return FAIL; // must not be preceded by other stores
3949 Node* adr = st->in(MemNode::Address);
3950 intptr_t offset;
3951 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
3952 if (alloc == NULL)
3953 return FAIL; // inscrutable address
3954 if (alloc != allocation())
3955 return FAIL; // wrong allocation! (store needs to float up)
3956 int size_in_bytes = st->memory_size();
3957 if ((size_in_bytes != 0) && (offset % size_in_bytes) != 0) {
3958 return FAIL; // mismatched access
3959 }
3960 Node* val = st->in(MemNode::ValueIn);
3961
3962 if (!detect_init_independence(val, phase))
3963 return FAIL; // stored value must be 'simple enough'
3964
3965 // The Store can be captured only if nothing after the allocation
3966 // and before the Store is using the memory location that the store
3967 // overwrites.
3968 bool failed = false;
3969 // If is_complete_with_arraycopy() is true the shape of the graph is
3970 // well defined and is safe so no need for extra checks.
3971 if (!is_complete_with_arraycopy()) {
3972 // We are going to look at each use of the memory state following
3973 // the allocation to make sure nothing reads the memory that the
3974 // Store writes.
3975 const TypePtr* t_adr = phase->type(adr)->isa_ptr();
3976 int alias_idx = phase->C->get_alias_index(t_adr);
3977 ResourceMark rm;
3978 Unique_Node_List mems;
3979 mems.push(mem);
3980 Node* unique_merge = NULL;
3981 for (uint next = 0; next < mems.size(); ++next) {
3982 Node *m = mems.at(next);
3983 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
3984 Node *n = m->fast_out(j);
3985 if (n->outcnt() == 0) {
3986 continue;
3987 }
3988 if (n == st) {
3989 continue;
3990 } else if (n->in(0) != NULL && n->in(0) != ctl) {
3991 // If the control of this use is different from the control
3992 // of the Store which is right after the InitializeNode then
3993 // this node cannot be between the InitializeNode and the
3994 // Store.
3995 continue;
3996 } else if (n->is_MergeMem()) {
3997 if (n->as_MergeMem()->memory_at(alias_idx) == m) {
3998 // We can hit a MergeMemNode (that will likely go away
3999 // later) that is a direct use of the memory state
4000 // following the InitializeNode on the same slice as the
4001 // store node that we'd like to capture. We need to check
4002 // the uses of the MergeMemNode.
4003 mems.push(n);
4004 }
4005 } else if (n->is_Mem()) {
4006 Node* other_adr = n->in(MemNode::Address);
4007 if (other_adr == adr) {
4008 failed = true;
4009 break;
4010 } else {
4011 const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr();
4012 if (other_t_adr != NULL) {
4013 int other_alias_idx = phase->C->get_alias_index(other_t_adr);
4014 if (other_alias_idx == alias_idx) {
4015 // A load from the same memory slice as the store right
4016 // after the InitializeNode. We check the control of the
4017 // object/array that is loaded from. If it's the same as
4018 // the store control then we cannot capture the store.
4019 assert(!n->is_Store(), "2 stores to same slice on same control?");
4020 Node* base = other_adr;
4021 if (base->is_Phi()) {
4022 // In rare case, base may be a PhiNode and it may read
4023 // the same memory slice between InitializeNode and store.
4024 failed = true;
4025 break;
4026 }
4027 assert(base->is_AddP(), "should be addp but is %s", base->Name());
4028 base = base->in(AddPNode::Base);
4029 if (base != NULL) {
4030 base = base->uncast();
4031 if (base->is_Proj() && base->in(0) == alloc) {
4032 failed = true;
4033 break;
4034 }
4035 }
4036 }
4037 }
4038 }
4039 } else {
4040 failed = true;
4041 break;
4042 }
4043 }
4044 }
4045 }
4046 if (failed) {
4047 if (!can_reshape) {
4048 // We decided we couldn't capture the store during parsing. We
4049 // should try again during the next IGVN once the graph is
4050 // cleaner.
4051 phase->C->record_for_igvn(st);
4052 }
4053 return FAIL;
4054 }
4055
4056 return offset; // success
4057 }
4058
4059 // Find the captured store in(i) which corresponds to the range
4060 // [start..start+size) in the initialized object.
4061 // If there is one, return its index i. If there isn't, return the
4062 // negative of the index where it should be inserted.
4063 // Return 0 if the queried range overlaps an initialization boundary
4064 // or if dead code is encountered.
4065 // If size_in_bytes is zero, do not bother with overlap checks.
4066 int InitializeNode::captured_store_insertion_point(intptr_t start,
4067 int size_in_bytes,
4068 PhaseTransform* phase) {
4069 const int FAIL = 0, MAX_STORE = MAX2(BytesPerLong, (int)MaxVectorSize);
4070
4071 if (is_complete())
4072 return FAIL; // arraycopy got here first; punt
4073
4074 assert(allocation() != NULL, "must be present");
4075
4076 // no negatives, no header fields:
4077 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
4078
4079 // after a certain size, we bail out on tracking all the stores:
4080 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
4081 if (start >= ti_limit) return FAIL;
4082
4083 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
4084 if (i >= limit) return -(int)i; // not found; here is where to put it
4085
4086 Node* st = in(i);
4087 intptr_t st_off = get_store_offset(st, phase);
4088 if (st_off < 0) {
4089 if (st != zero_memory()) {
4090 return FAIL; // bail out if there is dead garbage
4091 }
4092 } else if (st_off > start) {
4093 // ...we are done, since stores are ordered
4094 if (st_off < start + size_in_bytes) {
4095 return FAIL; // the next store overlaps
4096 }
4097 return -(int)i; // not found; here is where to put it
4098 } else if (st_off < start) {
4099 assert(st->as_Store()->memory_size() <= MAX_STORE, "");
4100 if (size_in_bytes != 0 &&
4101 start < st_off + MAX_STORE &&
4102 start < st_off + st->as_Store()->memory_size()) {
4103 return FAIL; // the previous store overlaps
4104 }
4105 } else {
4106 if (size_in_bytes != 0 &&
4107 st->as_Store()->memory_size() != size_in_bytes) {
4108 return FAIL; // mismatched store size
4109 }
4110 return i;
4111 }
4112
4113 ++i;
4114 }
4115 }
4116
4117 // Look for a captured store which initializes at the offset 'start'
4118 // with the given size. If there is no such store, and no other
4119 // initialization interferes, then return zero_memory (the memory
4120 // projection of the AllocateNode).
4121 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
4122 PhaseTransform* phase) {
4123 assert(stores_are_sane(phase), "");
4124 int i = captured_store_insertion_point(start, size_in_bytes, phase);
4125 if (i == 0) {
4126 return NULL; // something is dead
4127 } else if (i < 0) {
4128 return zero_memory(); // just primordial zero bits here
4129 } else {
4130 Node* st = in(i); // here is the store at this position
4131 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
4132 return st;
4133 }
4134 }
4135
4136 // Create, as a raw pointer, an address within my new object at 'offset'.
4137 Node* InitializeNode::make_raw_address(intptr_t offset,
4138 PhaseTransform* phase) {
4139 Node* addr = in(RawAddress);
4140 if (offset != 0) {
4141 Compile* C = phase->C;
4142 addr = phase->transform( new AddPNode(C->top(), addr,
4143 phase->MakeConX(offset)) );
4144 }
4145 return addr;
4146 }
4147
4148 // Clone the given store, converting it into a raw store
4149 // initializing a field or element of my new object.
4150 // Caller is responsible for retiring the original store,
4151 // with subsume_node or the like.
4152 //
4153 // From the example above InitializeNode::InitializeNode,
4154 // here are the old stores to be captured:
4155 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
4156 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
4157 //
4158 // Here is the changed code; note the extra edges on init:
4159 // alloc = (Allocate ...)
4160 // rawoop = alloc.RawAddress
4161 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
4162 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
4163 // init = (Initialize alloc.Control alloc.Memory rawoop
4164 // rawstore1 rawstore2)
4165 //
4166 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
4167 PhaseGVN* phase, bool can_reshape) {
4168 assert(stores_are_sane(phase), "");
4169
4170 if (start < 0) return NULL;
4171 assert(can_capture_store(st, phase, can_reshape) == start, "sanity");
4172
4173 Compile* C = phase->C;
4174 int size_in_bytes = st->memory_size();
4175 int i = captured_store_insertion_point(start, size_in_bytes, phase);
4176 if (i == 0) return NULL; // bail out
4177 Node* prev_mem = NULL; // raw memory for the captured store
4178 if (i > 0) {
4179 prev_mem = in(i); // there is a pre-existing store under this one
4180 set_req(i, C->top()); // temporarily disconnect it
4181 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
4182 } else {
4183 i = -i; // no pre-existing store
4184 prev_mem = zero_memory(); // a slice of the newly allocated object
4185 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
4186 set_req(--i, C->top()); // reuse this edge; it has been folded away
4187 else
4188 ins_req(i, C->top()); // build a new edge
4189 }
4190 Node* new_st = st->clone();
4191 new_st->set_req(MemNode::Control, in(Control));
4192 new_st->set_req(MemNode::Memory, prev_mem);
4193 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
4194 new_st = phase->transform(new_st);
4195
4196 // At this point, new_st might have swallowed a pre-existing store
4197 // at the same offset, or perhaps new_st might have disappeared,
4198 // if it redundantly stored the same value (or zero to fresh memory).
4199
4200 // In any case, wire it in:
4201 PhaseIterGVN* igvn = phase->is_IterGVN();
4202 if (igvn) {
4203 igvn->rehash_node_delayed(this);
4204 }
4205 set_req(i, new_st);
4206
4207 // The caller may now kill the old guy.
4208 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
4209 assert(check_st == new_st || check_st == NULL, "must be findable");
4210 assert(!is_complete(), "");
4211 return new_st;
4212 }
4213
4214 static bool store_constant(jlong* tiles, int num_tiles,
4215 intptr_t st_off, int st_size,
4216 jlong con) {
4217 if ((st_off & (st_size-1)) != 0)
4218 return false; // strange store offset (assume size==2**N)
4219 address addr = (address)tiles + st_off;
4220 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
4221 switch (st_size) {
4222 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
4223 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
4224 case sizeof(jint): *(jint*) addr = (jint) con; break;
4225 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
4226 default: return false; // strange store size (detect size!=2**N here)
4227 }
4228 return true; // return success to caller
4229 }
4230
4231 // Coalesce subword constants into int constants and possibly
4232 // into long constants. The goal, if the CPU permits,
4233 // is to initialize the object with a small number of 64-bit tiles.
4234 // Also, convert floating-point constants to bit patterns.
4235 // Non-constants are not relevant to this pass.
4236 //
4237 // In terms of the running example on InitializeNode::InitializeNode
4238 // and InitializeNode::capture_store, here is the transformation
4239 // of rawstore1 and rawstore2 into rawstore12:
4240 // alloc = (Allocate ...)
4241 // rawoop = alloc.RawAddress
4242 // tile12 = 0x00010002
4243 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
4244 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
4245 //
4246 void
4247 InitializeNode::coalesce_subword_stores(intptr_t header_size,
4248 Node* size_in_bytes,
4249 PhaseGVN* phase) {
4250 Compile* C = phase->C;
4251
4252 assert(stores_are_sane(phase), "");
4253 // Note: After this pass, they are not completely sane,
4254 // since there may be some overlaps.
4255
4256 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
4257
4258 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
4259 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
4260 size_limit = MIN2(size_limit, ti_limit);
4261 size_limit = align_up(size_limit, BytesPerLong);
4262 int num_tiles = size_limit / BytesPerLong;
4263
4264 // allocate space for the tile map:
4265 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
4266 jlong tiles_buf[small_len];
4267 Node* nodes_buf[small_len];
4268 jlong inits_buf[small_len];
4269 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
4270 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
4271 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
4272 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
4273 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
4274 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
4275 // tiles: exact bitwise model of all primitive constants
4276 // nodes: last constant-storing node subsumed into the tiles model
4277 // inits: which bytes (in each tile) are touched by any initializations
4278
4279 //// Pass A: Fill in the tile model with any relevant stores.
4280
4281 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
4282 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
4283 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
4284 Node* zmem = zero_memory(); // initially zero memory state
4285 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
4286 Node* st = in(i);
4287 intptr_t st_off = get_store_offset(st, phase);
4288
4289 // Figure out the store's offset and constant value:
4290 if (st_off < header_size) continue; //skip (ignore header)
4291 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
4292 int st_size = st->as_Store()->memory_size();
4293 if (st_off + st_size > size_limit) break;
4294
4295 // Record which bytes are touched, whether by constant or not.
4296 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
4297 continue; // skip (strange store size)
4298
4299 const Type* val = phase->type(st->in(MemNode::ValueIn));
4300 if (!val->singleton()) continue; //skip (non-con store)
4301 BasicType type = val->basic_type();
4302
4303 jlong con = 0;
4304 switch (type) {
4305 case T_INT: con = val->is_int()->get_con(); break;
4306 case T_LONG: con = val->is_long()->get_con(); break;
4307 case T_FLOAT: con = jint_cast(val->getf()); break;
4308 case T_DOUBLE: con = jlong_cast(val->getd()); break;
4309 default: continue; //skip (odd store type)
4310 }
4311
4312 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
4313 st->Opcode() == Op_StoreL) {
4314 continue; // This StoreL is already optimal.
4315 }
4316
4317 // Store down the constant.
4318 store_constant(tiles, num_tiles, st_off, st_size, con);
4319
4320 intptr_t j = st_off >> LogBytesPerLong;
4321
4322 if (type == T_INT && st_size == BytesPerInt
4323 && (st_off & BytesPerInt) == BytesPerInt) {
4324 jlong lcon = tiles[j];
4325 if (!Matcher::isSimpleConstant64(lcon) &&
4326 st->Opcode() == Op_StoreI) {
4327 // This StoreI is already optimal by itself.
4328 jint* intcon = (jint*) &tiles[j];
4329 intcon[1] = 0; // undo the store_constant()
4330
4331 // If the previous store is also optimal by itself, back up and
4332 // undo the action of the previous loop iteration... if we can.
4333 // But if we can't, just let the previous half take care of itself.
4334 st = nodes[j];
4335 st_off -= BytesPerInt;
4336 con = intcon[0];
4337 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) {
4338 assert(st_off >= header_size, "still ignoring header");
4339 assert(get_store_offset(st, phase) == st_off, "must be");
4340 assert(in(i-1) == zmem, "must be");
4341 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
4342 assert(con == tcon->is_int()->get_con(), "must be");
4343 // Undo the effects of the previous loop trip, which swallowed st:
4344 intcon[0] = 0; // undo store_constant()
4345 set_req(i-1, st); // undo set_req(i, zmem)
4346 nodes[j] = NULL; // undo nodes[j] = st
4347 --old_subword; // undo ++old_subword
4348 }
4349 continue; // This StoreI is already optimal.
4350 }
4351 }
4352
4353 // This store is not needed.
4354 set_req(i, zmem);
4355 nodes[j] = st; // record for the moment
4356 if (st_size < BytesPerLong) // something has changed
4357 ++old_subword; // includes int/float, but who's counting...
4358 else ++old_long;
4359 }
4360
4361 if ((old_subword + old_long) == 0)
4362 return; // nothing more to do
4363
4364 //// Pass B: Convert any non-zero tiles into optimal constant stores.
4365 // Be sure to insert them before overlapping non-constant stores.
4366 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
4367 for (int j = 0; j < num_tiles; j++) {
4368 jlong con = tiles[j];
4369 jlong init = inits[j];
4370 if (con == 0) continue;
4371 jint con0, con1; // split the constant, address-wise
4372 jint init0, init1; // split the init map, address-wise
4373 { union { jlong con; jint intcon[2]; } u;
4374 u.con = con;
4375 con0 = u.intcon[0];
4376 con1 = u.intcon[1];
4377 u.con = init;
4378 init0 = u.intcon[0];
4379 init1 = u.intcon[1];
4380 }
4381
4382 Node* old = nodes[j];
4383 assert(old != NULL, "need the prior store");
4384 intptr_t offset = (j * BytesPerLong);
4385
4386 bool split = !Matcher::isSimpleConstant64(con);
4387
4388 if (offset < header_size) {
4389 assert(offset + BytesPerInt >= header_size, "second int counts");
4390 assert(*(jint*)&tiles[j] == 0, "junk in header");
4391 split = true; // only the second word counts
4392 // Example: int a[] = { 42 ... }
4393 } else if (con0 == 0 && init0 == -1) {
4394 split = true; // first word is covered by full inits
4395 // Example: int a[] = { ... foo(), 42 ... }
4396 } else if (con1 == 0 && init1 == -1) {
4397 split = true; // second word is covered by full inits
4398 // Example: int a[] = { ... 42, foo() ... }
4399 }
4400
4401 // Here's a case where init0 is neither 0 nor -1:
4402 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
4403 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
4404 // In this case the tile is not split; it is (jlong)42.
4405 // The big tile is stored down, and then the foo() value is inserted.
4406 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
4407
4408 Node* ctl = old->in(MemNode::Control);
4409 Node* adr = make_raw_address(offset, phase);
4410 const TypePtr* atp = TypeRawPtr::BOTTOM;
4411
4412 // One or two coalesced stores to plop down.
4413 Node* st[2];
4414 intptr_t off[2];
4415 int nst = 0;
4416 if (!split) {
4417 ++new_long;
4418 off[nst] = offset;
4419 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
4420 phase->longcon(con), T_LONG, MemNode::unordered);
4421 } else {
4422 // Omit either if it is a zero.
4423 if (con0 != 0) {
4424 ++new_int;
4425 off[nst] = offset;
4426 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
4427 phase->intcon(con0), T_INT, MemNode::unordered);
4428 }
4429 if (con1 != 0) {
4430 ++new_int;
4431 offset += BytesPerInt;
4432 adr = make_raw_address(offset, phase);
4433 off[nst] = offset;
4434 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
4435 phase->intcon(con1), T_INT, MemNode::unordered);
4436 }
4437 }
4438
4439 // Insert second store first, then the first before the second.
4440 // Insert each one just before any overlapping non-constant stores.
4441 while (nst > 0) {
4442 Node* st1 = st[--nst];
4443 C->copy_node_notes_to(st1, old);
4444 st1 = phase->transform(st1);
4445 offset = off[nst];
4446 assert(offset >= header_size, "do not smash header");
4447 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
4448 guarantee(ins_idx != 0, "must re-insert constant store");
4449 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
4450 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
4451 set_req(--ins_idx, st1);
4452 else
4453 ins_req(ins_idx, st1);
4454 }
4455 }
4456
4457 if (PrintCompilation && WizardMode)
4458 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
4459 old_subword, old_long, new_int, new_long);
4460 if (C->log() != NULL)
4461 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
4462 old_subword, old_long, new_int, new_long);
4463
4464 // Clean up any remaining occurrences of zmem:
4465 remove_extra_zeroes();
4466 }
4467
4468 // Explore forward from in(start) to find the first fully initialized
4469 // word, and return its offset. Skip groups of subword stores which
4470 // together initialize full words. If in(start) is itself part of a
4471 // fully initialized word, return the offset of in(start). If there
4472 // are no following full-word stores, or if something is fishy, return
4473 // a negative value.
4474 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
4475 int int_map = 0;
4476 intptr_t int_map_off = 0;
4477 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
4478
4479 for (uint i = start, limit = req(); i < limit; i++) {
4480 Node* st = in(i);
4481
4482 intptr_t st_off = get_store_offset(st, phase);
4483 if (st_off < 0) break; // return conservative answer
4484
4485 int st_size = st->as_Store()->memory_size();
4486 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
4487 return st_off; // we found a complete word init
4488 }
4489
4490 // update the map:
4491
4492 intptr_t this_int_off = align_down(st_off, BytesPerInt);
4493 if (this_int_off != int_map_off) {
4494 // reset the map:
4495 int_map = 0;
4496 int_map_off = this_int_off;
4497 }
4498
4499 int subword_off = st_off - this_int_off;
4500 int_map |= right_n_bits(st_size) << subword_off;
4501 if ((int_map & FULL_MAP) == FULL_MAP) {
4502 return this_int_off; // we found a complete word init
4503 }
4504
4505 // Did this store hit or cross the word boundary?
4506 intptr_t next_int_off = align_down(st_off + st_size, BytesPerInt);
4507 if (next_int_off == this_int_off + BytesPerInt) {
4508 // We passed the current int, without fully initializing it.
4509 int_map_off = next_int_off;
4510 int_map >>= BytesPerInt;
4511 } else if (next_int_off > this_int_off + BytesPerInt) {
4512 // We passed the current and next int.
4513 return this_int_off + BytesPerInt;
4514 }
4515 }
4516
4517 return -1;
4518 }
4519
4520
4521 // Called when the associated AllocateNode is expanded into CFG.
4522 // At this point, we may perform additional optimizations.
4523 // Linearize the stores by ascending offset, to make memory
4524 // activity as coherent as possible.
4525 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
4526 intptr_t header_size,
4527 Node* size_in_bytes,
4528 PhaseIterGVN* phase) {
4529 assert(!is_complete(), "not already complete");
4530 assert(stores_are_sane(phase), "");
4531 assert(allocation() != NULL, "must be present");
4532
4533 remove_extra_zeroes();
4534
4535 if (ReduceFieldZeroing || ReduceBulkZeroing)
4536 // reduce instruction count for common initialization patterns
4537 coalesce_subword_stores(header_size, size_in_bytes, phase);
4538
4539 Node* zmem = zero_memory(); // initially zero memory state
4540 Node* inits = zmem; // accumulating a linearized chain of inits
4541 #ifdef ASSERT
4542 intptr_t first_offset = allocation()->minimum_header_size();
4543 intptr_t last_init_off = first_offset; // previous init offset
4544 intptr_t last_init_end = first_offset; // previous init offset+size
4545 intptr_t last_tile_end = first_offset; // previous tile offset+size
4546 #endif
4547 intptr_t zeroes_done = header_size;
4548
4549 bool do_zeroing = true; // we might give up if inits are very sparse
4550 int big_init_gaps = 0; // how many large gaps have we seen?
4551
4552 if (UseTLAB && ZeroTLAB) do_zeroing = false;
4553 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
4554
4555 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
4556 Node* st = in(i);
4557 intptr_t st_off = get_store_offset(st, phase);
4558 if (st_off < 0)
4559 break; // unknown junk in the inits
4560 if (st->in(MemNode::Memory) != zmem)
4561 break; // complicated store chains somehow in list
4562
4563 int st_size = st->as_Store()->memory_size();
4564 intptr_t next_init_off = st_off + st_size;
4565
4566 if (do_zeroing && zeroes_done < next_init_off) {
4567 // See if this store needs a zero before it or under it.
4568 intptr_t zeroes_needed = st_off;
4569
4570 if (st_size < BytesPerInt) {
4571 // Look for subword stores which only partially initialize words.
4572 // If we find some, we must lay down some word-level zeroes first,
4573 // underneath the subword stores.
4574 //
4575 // Examples:
4576 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
4577 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
4578 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
4579 //
4580 // Note: coalesce_subword_stores may have already done this,
4581 // if it was prompted by constant non-zero subword initializers.
4582 // But this case can still arise with non-constant stores.
4583
4584 intptr_t next_full_store = find_next_fullword_store(i, phase);
4585
4586 // In the examples above:
4587 // in(i) p q r s x y z
4588 // st_off 12 13 14 15 12 13 14
4589 // st_size 1 1 1 1 1 1 1
4590 // next_full_s. 12 16 16 16 16 16 16
4591 // z's_done 12 16 16 16 12 16 12
4592 // z's_needed 12 16 16 16 16 16 16
4593 // zsize 0 0 0 0 4 0 4
4594 if (next_full_store < 0) {
4595 // Conservative tack: Zero to end of current word.
4596 zeroes_needed = align_up(zeroes_needed, BytesPerInt);
4597 } else {
4598 // Zero to beginning of next fully initialized word.
4599 // Or, don't zero at all, if we are already in that word.
4600 assert(next_full_store >= zeroes_needed, "must go forward");
4601 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
4602 zeroes_needed = next_full_store;
4603 }
4604 }
4605
4606 if (zeroes_needed > zeroes_done) {
4607 intptr_t zsize = zeroes_needed - zeroes_done;
4608 // Do some incremental zeroing on rawmem, in parallel with inits.
4609 zeroes_done = align_down(zeroes_done, BytesPerInt);
4610 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
4611 allocation()->in(AllocateNode::DefaultValue),
4612 allocation()->in(AllocateNode::RawDefaultValue),
4613 zeroes_done, zeroes_needed,
4614 phase);
4615 zeroes_done = zeroes_needed;
4616 if (zsize > InitArrayShortSize && ++big_init_gaps > 2)
4617 do_zeroing = false; // leave the hole, next time
4618 }
4619 }
4620
4621 // Collect the store and move on:
4622 phase->replace_input_of(st, MemNode::Memory, inits);
4623 inits = st; // put it on the linearized chain
4624 set_req(i, zmem); // unhook from previous position
4625
4626 if (zeroes_done == st_off)
4627 zeroes_done = next_init_off;
4628
4629 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
4630
4631 #ifdef ASSERT
4632 // Various order invariants. Weaker than stores_are_sane because
4633 // a large constant tile can be filled in by smaller non-constant stores.
4634 assert(st_off >= last_init_off, "inits do not reverse");
4635 last_init_off = st_off;
4636 const Type* val = NULL;
4637 if (st_size >= BytesPerInt &&
4638 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
4639 (int)val->basic_type() < (int)T_OBJECT) {
4640 assert(st_off >= last_tile_end, "tiles do not overlap");
4641 assert(st_off >= last_init_end, "tiles do not overwrite inits");
4642 last_tile_end = MAX2(last_tile_end, next_init_off);
4643 } else {
4644 intptr_t st_tile_end = align_up(next_init_off, BytesPerLong);
4645 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
4646 assert(st_off >= last_init_end, "inits do not overlap");
4647 last_init_end = next_init_off; // it's a non-tile
4648 }
4649 #endif //ASSERT
4650 }
4651
4652 remove_extra_zeroes(); // clear out all the zmems left over
4653 add_req(inits);
4654
4655 if (!(UseTLAB && ZeroTLAB)) {
4656 // If anything remains to be zeroed, zero it all now.
4657 zeroes_done = align_down(zeroes_done, BytesPerInt);
4658 // if it is the last unused 4 bytes of an instance, forget about it
4659 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
4660 if (zeroes_done + BytesPerLong >= size_limit) {
4661 AllocateNode* alloc = allocation();
4662 assert(alloc != NULL, "must be present");
4663 if (alloc != NULL && alloc->Opcode() == Op_Allocate) {
4664 Node* klass_node = alloc->in(AllocateNode::KlassNode);
4665 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass();
4666 if (zeroes_done == k->layout_helper())
4667 zeroes_done = size_limit;
4668 }
4669 }
4670 if (zeroes_done < size_limit) {
4671 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
4672 allocation()->in(AllocateNode::DefaultValue),
4673 allocation()->in(AllocateNode::RawDefaultValue),
4674 zeroes_done, size_in_bytes, phase);
4675 }
4676 }
4677
4678 set_complete(phase);
4679 return rawmem;
4680 }
4681
4682
4683 #ifdef ASSERT
4684 bool InitializeNode::stores_are_sane(PhaseTransform* phase) {
4685 if (is_complete())
4686 return true; // stores could be anything at this point
4687 assert(allocation() != NULL, "must be present");
4688 intptr_t last_off = allocation()->minimum_header_size();
4689 for (uint i = InitializeNode::RawStores; i < req(); i++) {
4690 Node* st = in(i);
4691 intptr_t st_off = get_store_offset(st, phase);
4692 if (st_off < 0) continue; // ignore dead garbage
4693 if (last_off > st_off) {
4694 tty->print_cr("*** bad store offset at %d: " INTX_FORMAT " > " INTX_FORMAT, i, last_off, st_off);
4695 this->dump(2);
4696 assert(false, "ascending store offsets");
4697 return false;
4698 }
4699 last_off = st_off + st->as_Store()->memory_size();
4700 }
4701 return true;
4702 }
4703 #endif //ASSERT
4704
4705
4706
4707
4708 //============================MergeMemNode=====================================
4709 //
4710 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
4711 // contributing store or call operations. Each contributor provides the memory
4712 // state for a particular "alias type" (see Compile::alias_type). For example,
4713 // if a MergeMem has an input X for alias category #6, then any memory reference
4714 // to alias category #6 may use X as its memory state input, as an exact equivalent
4715 // to using the MergeMem as a whole.
4716 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
4717 //
4718 // (Here, the <N> notation gives the index of the relevant adr_type.)
4719 //
4720 // In one special case (and more cases in the future), alias categories overlap.
4721 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
4722 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
4723 // it is exactly equivalent to that state W:
4724 // MergeMem(<Bot>: W) <==> W
4725 //
4726 // Usually, the merge has more than one input. In that case, where inputs
4727 // overlap (i.e., one is Bot), the narrower alias type determines the memory
4728 // state for that type, and the wider alias type (Bot) fills in everywhere else:
4729 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
4730 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
4731 //
4732 // A merge can take a "wide" memory state as one of its narrow inputs.
4733 // This simply means that the merge observes out only the relevant parts of
4734 // the wide input. That is, wide memory states arriving at narrow merge inputs
4735 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
4736 //
4737 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
4738 // and that memory slices "leak through":
4739 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
4740 //
4741 // But, in such a cascade, repeated memory slices can "block the leak":
4742 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
4743 //
4744 // In the last example, Y is not part of the combined memory state of the
4745 // outermost MergeMem. The system must, of course, prevent unschedulable
4746 // memory states from arising, so you can be sure that the state Y is somehow
4747 // a precursor to state Y'.
4748 //
4749 //
4750 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
4751 // of each MergeMemNode array are exactly the numerical alias indexes, including
4752 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
4753 // Compile::alias_type (and kin) produce and manage these indexes.
4754 //
4755 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
4756 // (Note that this provides quick access to the top node inside MergeMem methods,
4757 // without the need to reach out via TLS to Compile::current.)
4758 //
4759 // As a consequence of what was just described, a MergeMem that represents a full
4760 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
4761 // containing all alias categories.
4762 //
4763 // MergeMem nodes never (?) have control inputs, so in(0) is NULL.
4764 //
4765 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
4766 // a memory state for the alias type <N>, or else the top node, meaning that
4767 // there is no particular input for that alias type. Note that the length of
4768 // a MergeMem is variable, and may be extended at any time to accommodate new
4769 // memory states at larger alias indexes. When merges grow, they are of course
4770 // filled with "top" in the unused in() positions.
4771 //
4772 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
4773 // (Top was chosen because it works smoothly with passes like GCM.)
4774 //
4775 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
4776 // the type of random VM bits like TLS references.) Since it is always the
4777 // first non-Bot memory slice, some low-level loops use it to initialize an
4778 // index variable: for (i = AliasIdxRaw; i < req(); i++).
4779 //
4780 //
4781 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
4782 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
4783 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
4784 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
4785 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
4786 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
4787 //
4788 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
4789 // really that different from the other memory inputs. An abbreviation called
4790 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
4791 //
4792 //
4793 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
4794 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
4795 // that "emerges though" the base memory will be marked as excluding the alias types
4796 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
4797 //
4798 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
4799 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
4800 //
4801 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
4802 // (It is currently unimplemented.) As you can see, the resulting merge is
4803 // actually a disjoint union of memory states, rather than an overlay.
4804 //
4805
4806 //------------------------------MergeMemNode-----------------------------------
4807 Node* MergeMemNode::make_empty_memory() {
4808 Node* empty_memory = (Node*) Compile::current()->top();
4809 assert(empty_memory->is_top(), "correct sentinel identity");
4810 return empty_memory;
4811 }
4812
4813 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
4814 init_class_id(Class_MergeMem);
4815 // all inputs are nullified in Node::Node(int)
4816 // set_input(0, NULL); // no control input
4817
4818 // Initialize the edges uniformly to top, for starters.
4819 Node* empty_mem = make_empty_memory();
4820 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
4821 init_req(i,empty_mem);
4822 }
4823 assert(empty_memory() == empty_mem, "");
4824
4825 if( new_base != NULL && new_base->is_MergeMem() ) {
4826 MergeMemNode* mdef = new_base->as_MergeMem();
4827 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
4828 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
4829 mms.set_memory(mms.memory2());
4830 }
4831 assert(base_memory() == mdef->base_memory(), "");
4832 } else {
4833 set_base_memory(new_base);
4834 }
4835 }
4836
4837 // Make a new, untransformed MergeMem with the same base as 'mem'.
4838 // If mem is itself a MergeMem, populate the result with the same edges.
4839 MergeMemNode* MergeMemNode::make(Node* mem) {
4840 return new MergeMemNode(mem);
4841 }
4842
4843 //------------------------------cmp--------------------------------------------
4844 uint MergeMemNode::hash() const { return NO_HASH; }
4845 bool MergeMemNode::cmp( const Node &n ) const {
4846 return (&n == this); // Always fail except on self
4847 }
4848
4849 //------------------------------Identity---------------------------------------
4850 Node* MergeMemNode::Identity(PhaseGVN* phase) {
4851 // Identity if this merge point does not record any interesting memory
4852 // disambiguations.
4853 Node* base_mem = base_memory();
4854 Node* empty_mem = empty_memory();
4855 if (base_mem != empty_mem) { // Memory path is not dead?
4856 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4857 Node* mem = in(i);
4858 if (mem != empty_mem && mem != base_mem) {
4859 return this; // Many memory splits; no change
4860 }
4861 }
4862 }
4863 return base_mem; // No memory splits; ID on the one true input
4864 }
4865
4866 //------------------------------Ideal------------------------------------------
4867 // This method is invoked recursively on chains of MergeMem nodes
4868 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4869 // Remove chain'd MergeMems
4870 //
4871 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
4872 // relative to the "in(Bot)". Since we are patching both at the same time,
4873 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
4874 // but rewrite each "in(i)" relative to the new "in(Bot)".
4875 Node *progress = NULL;
4876
4877
4878 Node* old_base = base_memory();
4879 Node* empty_mem = empty_memory();
4880 if (old_base == empty_mem)
4881 return NULL; // Dead memory path.
4882
4883 MergeMemNode* old_mbase;
4884 if (old_base != NULL && old_base->is_MergeMem())
4885 old_mbase = old_base->as_MergeMem();
4886 else
4887 old_mbase = NULL;
4888 Node* new_base = old_base;
4889
4890 // simplify stacked MergeMems in base memory
4891 if (old_mbase) new_base = old_mbase->base_memory();
4892
4893 // the base memory might contribute new slices beyond my req()
4894 if (old_mbase) grow_to_match(old_mbase);
4895
4896 // Look carefully at the base node if it is a phi.
4897 PhiNode* phi_base;
4898 if (new_base != NULL && new_base->is_Phi())
4899 phi_base = new_base->as_Phi();
4900 else
4901 phi_base = NULL;
4902
4903 Node* phi_reg = NULL;
4904 uint phi_len = (uint)-1;
4905 if (phi_base != NULL) {
4906 phi_reg = phi_base->region();
4907 phi_len = phi_base->req();
4908 // see if the phi is unfinished
4909 for (uint i = 1; i < phi_len; i++) {
4910 if (phi_base->in(i) == NULL) {
4911 // incomplete phi; do not look at it yet!
4912 phi_reg = NULL;
4913 phi_len = (uint)-1;
4914 break;
4915 }
4916 }
4917 }
4918
4919 // Note: We do not call verify_sparse on entry, because inputs
4920 // can normalize to the base_memory via subsume_node or similar
4921 // mechanisms. This method repairs that damage.
4922
4923 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
4924
4925 // Look at each slice.
4926 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4927 Node* old_in = in(i);
4928 // calculate the old memory value
4929 Node* old_mem = old_in;
4930 if (old_mem == empty_mem) old_mem = old_base;
4931 assert(old_mem == memory_at(i), "");
4932
4933 // maybe update (reslice) the old memory value
4934
4935 // simplify stacked MergeMems
4936 Node* new_mem = old_mem;
4937 MergeMemNode* old_mmem;
4938 if (old_mem != NULL && old_mem->is_MergeMem())
4939 old_mmem = old_mem->as_MergeMem();
4940 else
4941 old_mmem = NULL;
4942 if (old_mmem == this) {
4943 // This can happen if loops break up and safepoints disappear.
4944 // A merge of BotPtr (default) with a RawPtr memory derived from a
4945 // safepoint can be rewritten to a merge of the same BotPtr with
4946 // the BotPtr phi coming into the loop. If that phi disappears
4947 // also, we can end up with a self-loop of the mergemem.
4948 // In general, if loops degenerate and memory effects disappear,
4949 // a mergemem can be left looking at itself. This simply means
4950 // that the mergemem's default should be used, since there is
4951 // no longer any apparent effect on this slice.
4952 // Note: If a memory slice is a MergeMem cycle, it is unreachable
4953 // from start. Update the input to TOP.
4954 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
4955 }
4956 else if (old_mmem != NULL) {
4957 new_mem = old_mmem->memory_at(i);
4958 }
4959 // else preceding memory was not a MergeMem
4960
4961 // maybe store down a new value
4962 Node* new_in = new_mem;
4963 if (new_in == new_base) new_in = empty_mem;
4964
4965 if (new_in != old_in) {
4966 // Warning: Do not combine this "if" with the previous "if"
4967 // A memory slice might have be be rewritten even if it is semantically
4968 // unchanged, if the base_memory value has changed.
4969 set_req_X(i, new_in, phase);
4970 progress = this; // Report progress
4971 }
4972 }
4973
4974 if (new_base != old_base) {
4975 set_req_X(Compile::AliasIdxBot, new_base, phase);
4976 // Don't use set_base_memory(new_base), because we need to update du.
4977 assert(base_memory() == new_base, "");
4978 progress = this;
4979 }
4980
4981 if( base_memory() == this ) {
4982 // a self cycle indicates this memory path is dead
4983 set_req(Compile::AliasIdxBot, empty_mem);
4984 }
4985
4986 // Resolve external cycles by calling Ideal on a MergeMem base_memory
4987 // Recursion must occur after the self cycle check above
4988 if( base_memory()->is_MergeMem() ) {
4989 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
4990 Node *m = phase->transform(new_mbase); // Rollup any cycles
4991 if( m != NULL &&
4992 (m->is_top() ||
4993 (m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem)) ) {
4994 // propagate rollup of dead cycle to self
4995 set_req(Compile::AliasIdxBot, empty_mem);
4996 }
4997 }
4998
4999 if( base_memory() == empty_mem ) {
5000 progress = this;
5001 // Cut inputs during Parse phase only.
5002 // During Optimize phase a dead MergeMem node will be subsumed by Top.
5003 if( !can_reshape ) {
5004 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5005 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
5006 }
5007 }
5008 }
5009
5010 if( !progress && base_memory()->is_Phi() && can_reshape ) {
5011 // Check if PhiNode::Ideal's "Split phis through memory merges"
5012 // transform should be attempted. Look for this->phi->this cycle.
5013 uint merge_width = req();
5014 if (merge_width > Compile::AliasIdxRaw) {
5015 PhiNode* phi = base_memory()->as_Phi();
5016 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
5017 if (phi->in(i) == this) {
5018 phase->is_IterGVN()->_worklist.push(phi);
5019 break;
5020 }
5021 }
5022 }
5023 }
5024
5025 assert(progress || verify_sparse(), "please, no dups of base");
5026 return progress;
5027 }
5028
5029 //-------------------------set_base_memory-------------------------------------
5030 void MergeMemNode::set_base_memory(Node *new_base) {
5031 Node* empty_mem = empty_memory();
5032 set_req(Compile::AliasIdxBot, new_base);
5033 assert(memory_at(req()) == new_base, "must set default memory");
5034 // Clear out other occurrences of new_base:
5035 if (new_base != empty_mem) {
5036 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5037 if (in(i) == new_base) set_req(i, empty_mem);
5038 }
5039 }
5040 }
5041
5042 //------------------------------out_RegMask------------------------------------
5043 const RegMask &MergeMemNode::out_RegMask() const {
5044 return RegMask::Empty;
5045 }
5046
5047 //------------------------------dump_spec--------------------------------------
5048 #ifndef PRODUCT
5049 void MergeMemNode::dump_spec(outputStream *st) const {
5050 st->print(" {");
5051 Node* base_mem = base_memory();
5052 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
5053 Node* mem = (in(i) != NULL) ? memory_at(i) : base_mem;
5054 if (mem == base_mem) { st->print(" -"); continue; }
5055 st->print( " N%d:", mem->_idx );
5056 Compile::current()->get_adr_type(i)->dump_on(st);
5057 }
5058 st->print(" }");
5059 }
5060 #endif // !PRODUCT
5061
5062
5063 #ifdef ASSERT
5064 static bool might_be_same(Node* a, Node* b) {
5065 if (a == b) return true;
5066 if (!(a->is_Phi() || b->is_Phi())) return false;
5067 // phis shift around during optimization
5068 return true; // pretty stupid...
5069 }
5070
5071 // verify a narrow slice (either incoming or outgoing)
5072 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
5073 if (!VerifyAliases) return; // don't bother to verify unless requested
5074 if (VMError::is_error_reported()) return; // muzzle asserts when debugging an error
5075 if (Node::in_dump()) return; // muzzle asserts when printing
5076 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
5077 assert(n != NULL, "");
5078 // Elide intervening MergeMem's
5079 while (n->is_MergeMem()) {
5080 n = n->as_MergeMem()->memory_at(alias_idx);
5081 }
5082 Compile* C = Compile::current();
5083 const TypePtr* n_adr_type = n->adr_type();
5084 if (n == m->empty_memory()) {
5085 // Implicit copy of base_memory()
5086 } else if (n_adr_type != TypePtr::BOTTOM) {
5087 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type");
5088 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
5089 } else {
5090 // A few places like make_runtime_call "know" that VM calls are narrow,
5091 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
5092 bool expected_wide_mem = false;
5093 if (n == m->base_memory()) {
5094 expected_wide_mem = true;
5095 } else if (alias_idx == Compile::AliasIdxRaw ||
5096 n == m->memory_at(Compile::AliasIdxRaw)) {
5097 expected_wide_mem = true;
5098 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
5099 // memory can "leak through" calls on channels that
5100 // are write-once. Allow this also.
5101 expected_wide_mem = true;
5102 }
5103 assert(expected_wide_mem, "expected narrow slice replacement");
5104 }
5105 }
5106 #else // !ASSERT
5107 #define verify_memory_slice(m,i,n) (void)(0) // PRODUCT version is no-op
5108 #endif
5109
5110
5111 //-----------------------------memory_at---------------------------------------
5112 Node* MergeMemNode::memory_at(uint alias_idx) const {
5113 assert(alias_idx >= Compile::AliasIdxRaw ||
5114 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0,
5115 "must avoid base_memory and AliasIdxTop");
5116
5117 // Otherwise, it is a narrow slice.
5118 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
5119 Compile *C = Compile::current();
5120 if (is_empty_memory(n)) {
5121 // the array is sparse; empty slots are the "top" node
5122 n = base_memory();
5123 assert(Node::in_dump()
5124 || n == NULL || n->bottom_type() == Type::TOP
5125 || n->adr_type() == NULL // address is TOP
5126 || n->adr_type() == TypePtr::BOTTOM
5127 || n->adr_type() == TypeRawPtr::BOTTOM
5128 || Compile::current()->AliasLevel() == 0,
5129 "must be a wide memory");
5130 // AliasLevel == 0 if we are organizing the memory states manually.
5131 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
5132 } else {
5133 // make sure the stored slice is sane
5134 #ifdef ASSERT
5135 if (VMError::is_error_reported() || Node::in_dump()) {
5136 } else if (might_be_same(n, base_memory())) {
5137 // Give it a pass: It is a mostly harmless repetition of the base.
5138 // This can arise normally from node subsumption during optimization.
5139 } else {
5140 verify_memory_slice(this, alias_idx, n);
5141 }
5142 #endif
5143 }
5144 return n;
5145 }
5146
5147 //---------------------------set_memory_at-------------------------------------
5148 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
5149 verify_memory_slice(this, alias_idx, n);
5150 Node* empty_mem = empty_memory();
5151 if (n == base_memory()) n = empty_mem; // collapse default
5152 uint need_req = alias_idx+1;
5153 if (req() < need_req) {
5154 if (n == empty_mem) return; // already the default, so do not grow me
5155 // grow the sparse array
5156 do {
5157 add_req(empty_mem);
5158 } while (req() < need_req);
5159 }
5160 set_req( alias_idx, n );
5161 }
5162
5163
5164
5165 //--------------------------iteration_setup------------------------------------
5166 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
5167 if (other != NULL) {
5168 grow_to_match(other);
5169 // invariant: the finite support of mm2 is within mm->req()
5170 #ifdef ASSERT
5171 for (uint i = req(); i < other->req(); i++) {
5172 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
5173 }
5174 #endif
5175 }
5176 // Replace spurious copies of base_memory by top.
5177 Node* base_mem = base_memory();
5178 if (base_mem != NULL && !base_mem->is_top()) {
5179 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
5180 if (in(i) == base_mem)
5181 set_req(i, empty_memory());
5182 }
5183 }
5184 }
5185
5186 //---------------------------grow_to_match-------------------------------------
5187 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
5188 Node* empty_mem = empty_memory();
5189 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
5190 // look for the finite support of the other memory
5191 for (uint i = other->req(); --i >= req(); ) {
5192 if (other->in(i) != empty_mem) {
5193 uint new_len = i+1;
5194 while (req() < new_len) add_req(empty_mem);
5195 break;
5196 }
5197 }
5198 }
5199
5200 //---------------------------verify_sparse-------------------------------------
5201 #ifndef PRODUCT
5202 bool MergeMemNode::verify_sparse() const {
5203 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
5204 Node* base_mem = base_memory();
5205 // The following can happen in degenerate cases, since empty==top.
5206 if (is_empty_memory(base_mem)) return true;
5207 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5208 assert(in(i) != NULL, "sane slice");
5209 if (in(i) == base_mem) return false; // should have been the sentinel value!
5210 }
5211 return true;
5212 }
5213
5214 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
5215 Node* n;
5216 n = mm->in(idx);
5217 if (mem == n) return true; // might be empty_memory()
5218 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
5219 if (mem == n) return true;
5220 return false;
5221 }
5222 #endif // !PRODUCT