1 /*
2 * Copyright (c) 1997, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/systemDictionary.hpp"
27 #include "compiler/compileLog.hpp"
28 #include "memory/allocation.inline.hpp"
29 #include "oops/objArrayKlass.hpp"
30 #include "opto/addnode.hpp"
31 #include "opto/arraycopynode.hpp"
32 #include "opto/cfgnode.hpp"
33 #include "opto/compile.hpp"
34 #include "opto/connode.hpp"
35 #include "opto/convertnode.hpp"
36 #include "opto/loopnode.hpp"
37 #include "opto/machnode.hpp"
38 #include "opto/matcher.hpp"
39 #include "opto/memnode.hpp"
40 #include "opto/mulnode.hpp"
41 #include "opto/narrowptrnode.hpp"
42 #include "opto/phaseX.hpp"
43 #include "opto/regmask.hpp"
44 #include "opto/shenandoahSupport.hpp"
45 #include "utilities/copy.hpp"
46
47 // Portions of code courtesy of Clifford Click
48
49 // Optimization - Graph Style
50
51 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st);
52
53 //=============================================================================
54 uint MemNode::size_of() const { return sizeof(*this); }
55
56 const TypePtr *MemNode::adr_type() const {
57 Node* adr = in(Address);
58 if (adr == NULL) return NULL; // node is dead
59 const TypePtr* cross_check = NULL;
60 DEBUG_ONLY(cross_check = _adr_type);
61 return calculate_adr_type(adr->bottom_type(), cross_check);
62 }
63
64 #ifndef PRODUCT
65 void MemNode::dump_spec(outputStream *st) const {
66 if (in(Address) == NULL) return; // node is dead
67 #ifndef ASSERT
68 // fake the missing field
69 const TypePtr* _adr_type = NULL;
70 if (in(Address) != NULL)
71 _adr_type = in(Address)->bottom_type()->isa_ptr();
72 #endif
73 dump_adr_type(this, _adr_type, st);
74
75 Compile* C = Compile::current();
76 if( C->alias_type(_adr_type)->is_volatile() )
77 st->print(" Volatile!");
78 }
79
80 void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) {
81 st->print(" @");
82 if (adr_type == NULL) {
83 st->print("NULL");
84 } else {
85 adr_type->dump_on(st);
86 Compile* C = Compile::current();
87 Compile::AliasType* atp = NULL;
88 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type);
89 if (atp == NULL)
90 st->print(", idx=?\?;");
91 else if (atp->index() == Compile::AliasIdxBot)
92 st->print(", idx=Bot;");
93 else if (atp->index() == Compile::AliasIdxTop)
94 st->print(", idx=Top;");
95 else if (atp->index() == Compile::AliasIdxRaw)
96 st->print(", idx=Raw;");
97 else {
98 ciField* field = atp->field();
99 if (field) {
100 st->print(", name=");
101 field->print_name_on(st);
102 }
103 st->print(", idx=%d;", atp->index());
104 }
105 }
106 }
107
108 extern void print_alias_types();
109
110 #endif
111
112 Node *MemNode::optimize_simple_memory_chain(Node *mchain, const TypeOopPtr *t_oop, Node *load, PhaseGVN *phase) {
113 assert((t_oop != NULL), "sanity");
114 bool is_instance = t_oop->is_known_instance_field();
115 bool is_boxed_value_load = t_oop->is_ptr_to_boxed_value() &&
116 (load != NULL) && load->is_Load() &&
117 (phase->is_IterGVN() != NULL);
118 if (!(is_instance || is_boxed_value_load))
119 return mchain; // don't try to optimize non-instance types
120 uint instance_id = t_oop->instance_id();
121 Node *start_mem = phase->C->start()->proj_out(TypeFunc::Memory);
122 Node *prev = NULL;
123 Node *result = mchain;
124 while (prev != result) {
125 prev = result;
126 if (result == start_mem)
127 break; // hit one of our sentinels
128 // skip over a call which does not affect this memory slice
129 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {
130 Node *proj_in = result->in(0);
131 if (proj_in->is_Allocate() && proj_in->_idx == instance_id) {
132 break; // hit one of our sentinels
133 } else if (proj_in->is_Call()) {
134 // ArrayCopyNodes processed here as well
135 CallNode *call = proj_in->as_Call();
136 if (!call->may_modify(t_oop, phase)) { // returns false for instances
137 result = call->in(TypeFunc::Memory);
138 }
139 } else if (proj_in->is_Initialize()) {
140 AllocateNode* alloc = proj_in->as_Initialize()->allocation();
141 // Stop if this is the initialization for the object instance which
142 // contains this memory slice, otherwise skip over it.
143 if ((alloc == NULL) || (alloc->_idx == instance_id)) {
144 break;
145 }
146 if (is_instance) {
147 result = proj_in->in(TypeFunc::Memory);
148 } else if (is_boxed_value_load) {
149 Node* klass = alloc->in(AllocateNode::KlassNode);
150 const TypeKlassPtr* tklass = phase->type(klass)->is_klassptr();
151 if (tklass->klass_is_exact() && !tklass->klass()->equals(t_oop->klass())) {
152 result = proj_in->in(TypeFunc::Memory); // not related allocation
153 }
154 }
155 } else if (proj_in->is_MemBar()) {
156 if (ArrayCopyNode::may_modify(t_oop, proj_in->as_MemBar(), phase)) {
157 break;
158 }
159 result = proj_in->in(TypeFunc::Memory);
160 } else {
161 assert(false, "unexpected projection");
162 }
163 } else if (result->is_ClearArray()) {
164 if (!is_instance || !ClearArrayNode::step_through(&result, instance_id, phase)) {
165 // Can not bypass initialization of the instance
166 // we are looking for.
167 break;
168 }
169 // Otherwise skip it (the call updated 'result' value).
170 } else if (result->is_MergeMem()) {
171 result = step_through_mergemem(phase, result->as_MergeMem(), t_oop, NULL, tty);
172 }
173 }
174 return result;
175 }
176
177 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, Node *load, PhaseGVN *phase) {
178 const TypeOopPtr* t_oop = t_adr->isa_oopptr();
179 if (t_oop == NULL)
180 return mchain; // don't try to optimize non-oop types
181 Node* result = optimize_simple_memory_chain(mchain, t_oop, load, phase);
182 bool is_instance = t_oop->is_known_instance_field();
183 PhaseIterGVN *igvn = phase->is_IterGVN();
184 if (is_instance && igvn != NULL && result->is_Phi()) {
185 PhiNode *mphi = result->as_Phi();
186 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
187 const TypePtr *t = mphi->adr_type();
188 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
189 t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
190 t->is_oopptr()->cast_to_exactness(true)
191 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
192 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop) {
193 // clone the Phi with our address type
194 result = mphi->split_out_instance(t_adr, igvn);
195 } else {
196 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain");
197 }
198 }
199 return result;
200 }
201
202 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) {
203 uint alias_idx = phase->C->get_alias_index(tp);
204 Node *mem = mmem;
205 #ifdef ASSERT
206 {
207 // Check that current type is consistent with the alias index used during graph construction
208 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
209 bool consistent = adr_check == NULL || adr_check->empty() ||
210 phase->C->must_alias(adr_check, alias_idx );
211 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
212 if( !consistent && adr_check != NULL && !adr_check->empty() &&
213 tp->isa_aryptr() && tp->offset() == Type::OffsetBot &&
214 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot &&
215 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() ||
216 adr_check->offset() == oopDesc::klass_offset_in_bytes() ||
217 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) {
218 // don't assert if it is dead code.
219 consistent = true;
220 }
221 if( !consistent ) {
222 st->print("alias_idx==%d, adr_check==", alias_idx);
223 if( adr_check == NULL ) {
224 st->print("NULL");
225 } else {
226 adr_check->dump();
227 }
228 st->cr();
229 print_alias_types();
230 assert(consistent, "adr_check must match alias idx");
231 }
232 }
233 #endif
234 // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally
235 // means an array I have not precisely typed yet. Do not do any
236 // alias stuff with it any time soon.
237 const TypeOopPtr *toop = tp->isa_oopptr();
238 if( tp->base() != Type::AnyPtr &&
239 !(toop &&
240 toop->klass() != NULL &&
241 toop->klass()->is_java_lang_Object() &&
242 toop->offset() == Type::OffsetBot) ) {
243 // compress paths and change unreachable cycles to TOP
244 // If not, we can update the input infinitely along a MergeMem cycle
245 // Equivalent code in PhiNode::Ideal
246 Node* m = phase->transform(mmem);
247 // If transformed to a MergeMem, get the desired slice
248 // Otherwise the returned node represents memory for every slice
249 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
250 // Update input if it is progress over what we have now
251 }
252 return mem;
253 }
254
255 //--------------------------Ideal_common---------------------------------------
256 // Look for degenerate control and memory inputs. Bypass MergeMem inputs.
257 // Unhook non-raw memories from complete (macro-expanded) initializations.
258 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
259 // If our control input is a dead region, kill all below the region
260 Node *ctl = in(MemNode::Control);
261 if (ctl && remove_dead_region(phase, can_reshape))
262 return this;
263 ctl = in(MemNode::Control);
264 // Don't bother trying to transform a dead node
265 if (ctl && ctl->is_top()) return NodeSentinel;
266
267 PhaseIterGVN *igvn = phase->is_IterGVN();
268 // Wait if control on the worklist.
269 if (ctl && can_reshape && igvn != NULL) {
270 Node* bol = NULL;
271 Node* cmp = NULL;
272 if (ctl->in(0)->is_If()) {
273 assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity");
274 bol = ctl->in(0)->in(1);
275 if (bol->is_Bool())
276 cmp = ctl->in(0)->in(1)->in(1);
277 }
278 if (igvn->_worklist.member(ctl) ||
279 (bol != NULL && igvn->_worklist.member(bol)) ||
280 (cmp != NULL && igvn->_worklist.member(cmp)) ) {
281 // This control path may be dead.
282 // Delay this memory node transformation until the control is processed.
283 phase->is_IterGVN()->_worklist.push(this);
284 return NodeSentinel; // caller will return NULL
285 }
286 }
287 // Ignore if memory is dead, or self-loop
288 Node *mem = in(MemNode::Memory);
289 if (phase->type( mem ) == Type::TOP) return NodeSentinel; // caller will return NULL
290 assert(mem != this, "dead loop in MemNode::Ideal");
291
292 if (can_reshape && igvn != NULL && igvn->_worklist.member(mem)) {
293 // This memory slice may be dead.
294 // Delay this mem node transformation until the memory is processed.
295 phase->is_IterGVN()->_worklist.push(this);
296 return NodeSentinel; // caller will return NULL
297 }
298
299 Node *address = in(MemNode::Address);
300 const Type *t_adr = phase->type(address);
301 if (t_adr == Type::TOP) return NodeSentinel; // caller will return NULL
302
303 if (can_reshape && igvn != NULL &&
304 (igvn->_worklist.member(address) ||
305 igvn->_worklist.size() > 0 && (t_adr != adr_type())) ) {
306 // The address's base and type may change when the address is processed.
307 // Delay this mem node transformation until the address is processed.
308 phase->is_IterGVN()->_worklist.push(this);
309 return NodeSentinel; // caller will return NULL
310 }
311
312 // Do NOT remove or optimize the next lines: ensure a new alias index
313 // is allocated for an oop pointer type before Escape Analysis.
314 // Note: C++ will not remove it since the call has side effect.
315 if (t_adr->isa_oopptr()) {
316 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr());
317 }
318
319 Node* base = NULL;
320 if (address->is_AddP()) {
321 base = address->in(AddPNode::Base);
322 }
323 if (base != NULL && phase->type(base)->higher_equal(TypePtr::NULL_PTR) &&
324 !t_adr->isa_rawptr()) {
325 // Note: raw address has TOP base and top->higher_equal(TypePtr::NULL_PTR) is true.
326 // Skip this node optimization if its address has TOP base.
327 return NodeSentinel; // caller will return NULL
328 }
329
330 // Avoid independent memory operations
331 Node* old_mem = mem;
332
333 // The code which unhooks non-raw memories from complete (macro-expanded)
334 // initializations was removed. After macro-expansion all stores catched
335 // by Initialize node became raw stores and there is no information
336 // which memory slices they modify. So it is unsafe to move any memory
337 // operation above these stores. Also in most cases hooked non-raw memories
338 // were already unhooked by using information from detect_ptr_independence()
339 // and find_previous_store().
340
341 if (mem->is_MergeMem()) {
342 MergeMemNode* mmem = mem->as_MergeMem();
343 const TypePtr *tp = t_adr->is_ptr();
344
345 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
346 }
347
348 if (mem != old_mem) {
349 set_req(MemNode::Memory, mem);
350 if (can_reshape && old_mem->outcnt() == 0) {
351 igvn->_worklist.push(old_mem);
352 }
353 if (phase->type( mem ) == Type::TOP) return NodeSentinel;
354 return this;
355 }
356
357 // let the subclass continue analyzing...
358 return NULL;
359 }
360
361 // Helper function for proving some simple control dominations.
362 // Attempt to prove that all control inputs of 'dom' dominate 'sub'.
363 // Already assumes that 'dom' is available at 'sub', and that 'sub'
364 // is not a constant (dominated by the method's StartNode).
365 // Used by MemNode::find_previous_store to prove that the
366 // control input of a memory operation predates (dominates)
367 // an allocation it wants to look past.
368 bool MemNode::all_controls_dominate(Node* dom, Node* sub) {
369 if (dom == NULL || dom->is_top() || sub == NULL || sub->is_top())
370 return false; // Conservative answer for dead code
371
372 // Check 'dom'. Skip Proj and CatchProj nodes.
373 dom = dom->find_exact_control(dom);
374 if (dom == NULL || dom->is_top())
375 return false; // Conservative answer for dead code
376
377 if (dom == sub) {
378 // For the case when, for example, 'sub' is Initialize and the original
379 // 'dom' is Proj node of the 'sub'.
380 return false;
381 }
382
383 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub)
384 return true;
385
386 // 'dom' dominates 'sub' if its control edge and control edges
387 // of all its inputs dominate or equal to sub's control edge.
388
389 // Currently 'sub' is either Allocate, Initialize or Start nodes.
390 // Or Region for the check in LoadNode::Ideal();
391 // 'sub' should have sub->in(0) != NULL.
392 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() ||
393 sub->is_Region() || sub->is_Call(), "expecting only these nodes");
394
395 // Get control edge of 'sub'.
396 Node* orig_sub = sub;
397 sub = sub->find_exact_control(sub->in(0));
398 if (sub == NULL || sub->is_top())
399 return false; // Conservative answer for dead code
400
401 assert(sub->is_CFG(), "expecting control");
402
403 if (sub == dom)
404 return true;
405
406 if (sub->is_Start() || sub->is_Root())
407 return false;
408
409 {
410 // Check all control edges of 'dom'.
411
412 ResourceMark rm;
413 Arena* arena = Thread::current()->resource_area();
414 Node_List nlist(arena);
415 Unique_Node_List dom_list(arena);
416
417 dom_list.push(dom);
418 bool only_dominating_controls = false;
419
420 for (uint next = 0; next < dom_list.size(); next++) {
421 Node* n = dom_list.at(next);
422 if (n == orig_sub)
423 return false; // One of dom's inputs dominated by sub.
424 if (!n->is_CFG() && n->pinned()) {
425 // Check only own control edge for pinned non-control nodes.
426 n = n->find_exact_control(n->in(0));
427 if (n == NULL || n->is_top())
428 return false; // Conservative answer for dead code
429 assert(n->is_CFG(), "expecting control");
430 dom_list.push(n);
431 } else if (n->is_Con() || n->is_Start() || n->is_Root()) {
432 only_dominating_controls = true;
433 } else if (n->is_CFG()) {
434 if (n->dominates(sub, nlist))
435 only_dominating_controls = true;
436 else
437 return false;
438 } else {
439 // First, own control edge.
440 Node* m = n->find_exact_control(n->in(0));
441 if (m != NULL) {
442 if (m->is_top())
443 return false; // Conservative answer for dead code
444 dom_list.push(m);
445 }
446 // Now, the rest of edges.
447 uint cnt = n->req();
448 for (uint i = 1; i < cnt; i++) {
449 m = n->find_exact_control(n->in(i));
450 if (m == NULL || m->is_top())
451 continue;
452 dom_list.push(m);
453 }
454 }
455 }
456 return only_dominating_controls;
457 }
458 }
459
460 //---------------------detect_ptr_independence---------------------------------
461 // Used by MemNode::find_previous_store to prove that two base
462 // pointers are never equal.
463 // The pointers are accompanied by their associated allocations,
464 // if any, which have been previously discovered by the caller.
465 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
466 Node* p2, AllocateNode* a2,
467 PhaseTransform* phase) {
468 // Attempt to prove that these two pointers cannot be aliased.
469 // They may both manifestly be allocations, and they should differ.
470 // Or, if they are not both allocations, they can be distinct constants.
471 // Otherwise, one is an allocation and the other a pre-existing value.
472 if (a1 == NULL && a2 == NULL) { // neither an allocation
473 return (p1 != p2) && p1->is_Con() && p2->is_Con();
474 } else if (a1 != NULL && a2 != NULL) { // both allocations
475 return (a1 != a2);
476 } else if (a1 != NULL) { // one allocation a1
477 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.)
478 return all_controls_dominate(p2, a1);
479 } else { //(a2 != NULL) // one allocation a2
480 return all_controls_dominate(p1, a2);
481 }
482 return false;
483 }
484
485
486 // Find an arraycopy that must have set (can_see_stored_value=true) or
487 // could have set (can_see_stored_value=false) the value for this load
488 Node* LoadNode::find_previous_arraycopy(PhaseTransform* phase, Node* ld_alloc, Node*& mem, bool can_see_stored_value) const {
489 if (mem->is_Proj() && mem->in(0) != NULL && (mem->in(0)->Opcode() == Op_MemBarStoreStore ||
490 mem->in(0)->Opcode() == Op_MemBarCPUOrder)) {
491 Node* mb = mem->in(0);
492 if (mb->in(0) != NULL && mb->in(0)->is_Proj() &&
493 mb->in(0)->in(0) != NULL && mb->in(0)->in(0)->is_ArrayCopy()) {
494 ArrayCopyNode* ac = mb->in(0)->in(0)->as_ArrayCopy();
495 if (ac->is_clonebasic()) {
496 intptr_t offset;
497 AllocateNode* alloc = AllocateNode::Ideal_allocation(ac->in(ArrayCopyNode::Dest), phase, offset);
498 assert(alloc != NULL && alloc->initialization()->is_complete_with_arraycopy(), "broken allocation");
499 if (alloc == ld_alloc) {
500 return ac;
501 }
502 }
503 }
504 } else if (mem->is_Proj() && mem->in(0) != NULL && mem->in(0)->is_ArrayCopy()) {
505 ArrayCopyNode* ac = mem->in(0)->as_ArrayCopy();
506
507 if (ac->is_arraycopy_validated() ||
508 ac->is_copyof_validated() ||
509 ac->is_copyofrange_validated()) {
510 Node* ld_addp = in(MemNode::Address);
511 if (ld_addp->is_AddP()) {
512 Node* ld_base = ld_addp->in(AddPNode::Address);
513 Node* ld_offs = ld_addp->in(AddPNode::Offset);
514
515 Node* dest = ac->in(ArrayCopyNode::Dest);
516
517 if (dest == ld_base) {
518 const TypeX *ld_offs_t = phase->type(ld_offs)->isa_intptr_t();
519 if (ac->modifies(ld_offs_t->_lo, ld_offs_t->_hi, phase, can_see_stored_value)) {
520 return ac;
521 }
522 if (!can_see_stored_value) {
523 mem = ac->in(TypeFunc::Memory);
524 }
525 }
526 }
527 }
528 }
529 return NULL;
530 }
531
532 // The logic for reordering loads and stores uses four steps:
533 // (a) Walk carefully past stores and initializations which we
534 // can prove are independent of this load.
535 // (b) Observe that the next memory state makes an exact match
536 // with self (load or store), and locate the relevant store.
537 // (c) Ensure that, if we were to wire self directly to the store,
538 // the optimizer would fold it up somehow.
539 // (d) Do the rewiring, and return, depending on some other part of
540 // the optimizer to fold up the load.
541 // This routine handles steps (a) and (b). Steps (c) and (d) are
542 // specific to loads and stores, so they are handled by the callers.
543 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.)
544 //
545 Node* MemNode::find_previous_store(PhaseTransform* phase) {
546 Node* ctrl = in(MemNode::Control);
547 Node* adr = in(MemNode::Address);
548 intptr_t offset = 0;
549 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
550 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase);
551
552 if (offset == Type::OffsetBot)
553 return NULL; // cannot unalias unless there are precise offsets
554
555 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr();
556
557 intptr_t size_in_bytes = memory_size();
558
559 Node* mem = in(MemNode::Memory); // start searching here...
560
561 int cnt = 50; // Cycle limiter
562 for (;;) { // While we can dance past unrelated stores...
563 if (--cnt < 0) break; // Caught in cycle or a complicated dance?
564
565 Node* prev = mem;
566 if (mem->is_Store()) {
567 Node* st_adr = mem->in(MemNode::Address);
568 intptr_t st_offset = 0;
569 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
570 if (st_base == NULL)
571 break; // inscrutable pointer
572 if (st_offset != offset && st_offset != Type::OffsetBot) {
573 const int MAX_STORE = BytesPerLong;
574 if (st_offset >= offset + size_in_bytes ||
575 st_offset <= offset - MAX_STORE ||
576 st_offset <= offset - mem->as_Store()->memory_size()) {
577 // Success: The offsets are provably independent.
578 // (You may ask, why not just test st_offset != offset and be done?
579 // The answer is that stores of different sizes can co-exist
580 // in the same sequence of RawMem effects. We sometimes initialize
581 // a whole 'tile' of array elements with a single jint or jlong.)
582 mem = mem->in(MemNode::Memory);
583 continue; // (a) advance through independent store memory
584 }
585 }
586 if (st_base != base &&
587 detect_ptr_independence(base, alloc,
588 st_base,
589 AllocateNode::Ideal_allocation(st_base, phase),
590 phase)) {
591 // Success: The bases are provably independent.
592 mem = mem->in(MemNode::Memory);
593 continue; // (a) advance through independent store memory
594 }
595
596 // (b) At this point, if the bases or offsets do not agree, we lose,
597 // since we have not managed to prove 'this' and 'mem' independent.
598 if (st_base == base && st_offset == offset) {
599 return mem; // let caller handle steps (c), (d)
600 }
601
602 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
603 InitializeNode* st_init = mem->in(0)->as_Initialize();
604 AllocateNode* st_alloc = st_init->allocation();
605 if (st_alloc == NULL)
606 break; // something degenerated
607 bool known_identical = false;
608 bool known_independent = false;
609 if (alloc == st_alloc)
610 known_identical = true;
611 else if (alloc != NULL)
612 known_independent = true;
613 else if (all_controls_dominate(this, st_alloc))
614 known_independent = true;
615
616 if (known_independent) {
617 // The bases are provably independent: Either they are
618 // manifestly distinct allocations, or else the control
619 // of this load dominates the store's allocation.
620 int alias_idx = phase->C->get_alias_index(adr_type());
621 if (alias_idx == Compile::AliasIdxRaw) {
622 mem = st_alloc->in(TypeFunc::Memory);
623 } else {
624 mem = st_init->memory(alias_idx);
625 }
626 continue; // (a) advance through independent store memory
627 }
628
629 // (b) at this point, if we are not looking at a store initializing
630 // the same allocation we are loading from, we lose.
631 if (known_identical) {
632 // From caller, can_see_stored_value will consult find_captured_store.
633 return mem; // let caller handle steps (c), (d)
634 }
635
636 } else if (find_previous_arraycopy(phase, alloc, mem, false) != NULL) {
637 if (prev != mem) {
638 // Found an arraycopy but it doesn't affect that load
639 continue;
640 }
641 // Found an arraycopy that may affect that load
642 return mem;
643 } else if (addr_t != NULL && addr_t->is_known_instance_field()) {
644 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
645 if (mem->is_Proj() && mem->in(0)->is_Call()) {
646 // ArrayCopyNodes processed here as well.
647 CallNode *call = mem->in(0)->as_Call();
648 if (!call->may_modify(addr_t, phase)) {
649 mem = call->in(TypeFunc::Memory);
650 continue; // (a) advance through independent call memory
651 }
652 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) {
653 if (ArrayCopyNode::may_modify(addr_t, mem->in(0)->as_MemBar(), phase)) {
654 break;
655 }
656 mem = mem->in(0)->in(TypeFunc::Memory);
657 continue; // (a) advance through independent MemBar memory
658 } else if (mem->is_ClearArray()) {
659 if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) {
660 // (the call updated 'mem' value)
661 continue; // (a) advance through independent allocation memory
662 } else {
663 // Can not bypass initialization of the instance
664 // we are looking for.
665 return mem;
666 }
667 } else if (mem->is_MergeMem()) {
668 int alias_idx = phase->C->get_alias_index(adr_type());
669 mem = mem->as_MergeMem()->memory_at(alias_idx);
670 continue; // (a) advance through independent MergeMem memory
671 }
672 }
673
674 // Unless there is an explicit 'continue', we must bail out here,
675 // because 'mem' is an inscrutable memory state (e.g., a call).
676 break;
677 }
678
679 return NULL; // bail out
680 }
681
682 //----------------------calculate_adr_type-------------------------------------
683 // Helper function. Notices when the given type of address hits top or bottom.
684 // Also, asserts a cross-check of the type against the expected address type.
685 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
686 if (t == Type::TOP) return NULL; // does not touch memory any more?
687 #ifdef PRODUCT
688 cross_check = NULL;
689 #else
690 if (!VerifyAliases || is_error_reported() || Node::in_dump()) cross_check = NULL;
691 #endif
692 const TypePtr* tp = t->isa_ptr();
693 if (tp == NULL) {
694 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
695 return TypePtr::BOTTOM; // touches lots of memory
696 } else {
697 #ifdef ASSERT
698 // %%%% [phh] We don't check the alias index if cross_check is
699 // TypeRawPtr::BOTTOM. Needs to be investigated.
700 if (cross_check != NULL &&
701 cross_check != TypePtr::BOTTOM &&
702 cross_check != TypeRawPtr::BOTTOM) {
703 // Recheck the alias index, to see if it has changed (due to a bug).
704 Compile* C = Compile::current();
705 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
706 "must stay in the original alias category");
707 // The type of the address must be contained in the adr_type,
708 // disregarding "null"-ness.
709 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
710 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
711 assert(cross_check->meet(tp_notnull) == cross_check->remove_speculative(),
712 "real address must not escape from expected memory type");
713 }
714 #endif
715 return tp;
716 }
717 }
718
719 //=============================================================================
720 // Should LoadNode::Ideal() attempt to remove control edges?
721 bool LoadNode::can_remove_control() const {
722 return true;
723 }
724 uint LoadNode::size_of() const { return sizeof(*this); }
725 uint LoadNode::cmp( const Node &n ) const
726 { return !Type::cmp( _type, ((LoadNode&)n)._type ); }
727 const Type *LoadNode::bottom_type() const { return _type; }
728 uint LoadNode::ideal_reg() const {
729 return _type->ideal_reg();
730 }
731
732 #ifndef PRODUCT
733 void LoadNode::dump_spec(outputStream *st) const {
734 MemNode::dump_spec(st);
735 if( !Verbose && !WizardMode ) {
736 // standard dump does this in Verbose and WizardMode
737 st->print(" #"); _type->dump_on(st);
738 }
739 if (!_depends_only_on_test) {
740 st->print(" (does not depend only on test)");
741 }
742 }
743 #endif
744
745 #ifdef ASSERT
746 //----------------------------is_immutable_value-------------------------------
747 // Helper function to allow a raw load without control edge for some cases
748 bool LoadNode::is_immutable_value(Node* adr) {
749 return (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() &&
750 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal &&
751 (adr->in(AddPNode::Offset)->find_intptr_t_con(-1) ==
752 in_bytes(JavaThread::osthread_offset())));
753 }
754 #endif
755
756 //----------------------------LoadNode::make-----------------------------------
757 // Polymorphic factory method:
758 Node *LoadNode::make(PhaseGVN& gvn, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt, MemOrd mo, ControlDependency control_dependency) {
759 Compile* C = gvn.C;
760
761 // sanity check the alias category against the created node type
762 assert(!(adr_type->isa_oopptr() &&
763 adr_type->offset() == oopDesc::klass_offset_in_bytes()),
764 "use LoadKlassNode instead");
765 assert(!(adr_type->isa_aryptr() &&
766 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
767 "use LoadRangeNode instead");
768 // Check control edge of raw loads
769 assert( ctl != NULL || C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
770 // oop will be recorded in oop map if load crosses safepoint
771 rt->isa_oopptr() || is_immutable_value(adr),
772 "raw memory operations should have control edge");
773 switch (bt) {
774 case T_BOOLEAN: return new LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency);
775 case T_BYTE: return new LoadBNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency);
776 case T_INT: return new LoadINode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency);
777 case T_CHAR: return new LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency);
778 case T_SHORT: return new LoadSNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency);
779 case T_LONG: return new LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency);
780 case T_FLOAT: return new LoadFNode (ctl, mem, adr, adr_type, rt, mo, control_dependency);
781 case T_DOUBLE: return new LoadDNode (ctl, mem, adr, adr_type, rt, mo, control_dependency);
782 case T_ADDRESS: return new LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency);
783 case T_OBJECT:
784 #ifdef _LP64
785 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
786 Node* load = gvn.transform(new LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo, control_dependency));
787 return new DecodeNNode(load, load->bottom_type()->make_ptr());
788 } else
789 #endif
790 {
791 assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop");
792 return new LoadPNode(ctl, mem, adr, adr_type, rt->is_oopptr(), mo, control_dependency);
793 }
794 }
795 ShouldNotReachHere();
796 return (LoadNode*)NULL;
797 }
798
799 LoadLNode* LoadLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo, ControlDependency control_dependency) {
800 bool require_atomic = true;
801 return new LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency, require_atomic);
802 }
803
804 LoadDNode* LoadDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo, ControlDependency control_dependency) {
805 bool require_atomic = true;
806 return new LoadDNode(ctl, mem, adr, adr_type, rt, mo, control_dependency, require_atomic);
807 }
808
809
810
811 //------------------------------hash-------------------------------------------
812 uint LoadNode::hash() const {
813 // unroll addition of interesting fields
814 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
815 }
816
817 static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) {
818 if ((atp != NULL) && (atp->index() >= Compile::AliasIdxRaw)) {
819 bool non_volatile = (atp->field() != NULL) && !atp->field()->is_volatile();
820 bool is_stable_ary = FoldStableValues &&
821 (tp != NULL) && (tp->isa_aryptr() != NULL) &&
822 tp->isa_aryptr()->is_stable();
823
824 return (eliminate_boxing && non_volatile) || is_stable_ary;
825 }
826
827 return false;
828 }
829
830 // Is the value loaded previously stored by an arraycopy? If so return
831 // a load node that reads from the source array so we may be able to
832 // optimize out the ArrayCopy node later.
833 Node* LoadNode::can_see_arraycopy_value(Node* st, PhaseTransform* phase) const {
834 Node* ld_adr = in(MemNode::Address);
835 intptr_t ld_off = 0;
836 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
837 Node* ac = find_previous_arraycopy(phase, ld_alloc, st, true);
838 if (ac != NULL) {
839 assert(ac->is_ArrayCopy(), "what kind of node can this be?");
840
841 Node* ld = clone();
842 if (ac->as_ArrayCopy()->is_clonebasic()) {
843 assert(ld_alloc != NULL, "need an alloc");
844 Node* addp = in(MemNode::Address)->clone();
845 assert(addp->is_AddP(), "address must be addp");
846 assert(addp->in(AddPNode::Base) == ac->in(ArrayCopyNode::Dest)->in(AddPNode::Base), "strange pattern");
847 assert(addp->in(AddPNode::Address) == ac->in(ArrayCopyNode::Dest)->in(AddPNode::Address), "strange pattern");
848 addp->set_req(AddPNode::Base, ac->in(ArrayCopyNode::Src)->in(AddPNode::Base));
849 addp->set_req(AddPNode::Address, ac->in(ArrayCopyNode::Src)->in(AddPNode::Address));
850 ld->set_req(MemNode::Address, phase->transform(addp));
851 if (in(0) != NULL) {
852 assert(ld_alloc->in(0) != NULL, "alloc must have control");
853 ld->set_req(0, ld_alloc->in(0));
854 }
855 } else {
856 Node* addp = in(MemNode::Address)->clone();
857 assert(addp->in(AddPNode::Base) == addp->in(AddPNode::Address), "should be");
858 addp->set_req(AddPNode::Base, ac->in(ArrayCopyNode::Src));
859 addp->set_req(AddPNode::Address, ac->in(ArrayCopyNode::Src));
860
861 const TypeAryPtr* ary_t = phase->type(in(MemNode::Address))->isa_aryptr();
862 BasicType ary_elem = ary_t->klass()->as_array_klass()->element_type()->basic_type();
863 uint header = arrayOopDesc::base_offset_in_bytes(ary_elem);
864 uint shift = exact_log2(type2aelembytes(ary_elem));
865
866 Node* diff = phase->transform(new SubINode(ac->in(ArrayCopyNode::SrcPos), ac->in(ArrayCopyNode::DestPos)));
867 #ifdef _LP64
868 diff = phase->transform(new ConvI2LNode(diff));
869 #endif
870 diff = phase->transform(new LShiftXNode(diff, phase->intcon(shift)));
871
872 Node* offset = phase->transform(new AddXNode(addp->in(AddPNode::Offset), diff));
873 addp->set_req(AddPNode::Offset, offset);
874 ld->set_req(MemNode::Address, phase->transform(addp));
875
876 if (in(0) != NULL) {
877 assert(ac->in(0) != NULL, "alloc must have control");
878 ld->set_req(0, ac->in(0));
879 }
880 }
881 // load depends on the tests that validate the arraycopy
882 ld->as_Load()->_depends_only_on_test = Pinned;
883 return ld;
884 }
885 return NULL;
886 }
887
888
889 //---------------------------can_see_stored_value------------------------------
890 // This routine exists to make sure this set of tests is done the same
891 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
892 // will change the graph shape in a way which makes memory alive twice at the
893 // same time (uses the Oracle model of aliasing), then some
894 // LoadXNode::Identity will fold things back to the equivalence-class model
895 // of aliasing.
896 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const {
897 Node* ld_adr = in(MemNode::Address);
898 intptr_t ld_off = 0;
899 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
900 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
901 Compile::AliasType* atp = (tp != NULL) ? phase->C->alias_type(tp) : NULL;
902 // This is more general than load from boxing objects.
903 if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) {
904 uint alias_idx = atp->index();
905 bool final = !atp->is_rewritable();
906 Node* result = NULL;
907 Node* current = st;
908 // Skip through chains of MemBarNodes checking the MergeMems for
909 // new states for the slice of this load. Stop once any other
910 // kind of node is encountered. Loads from final memory can skip
911 // through any kind of MemBar but normal loads shouldn't skip
912 // through MemBarAcquire since the could allow them to move out of
913 // a synchronized region.
914 while (current->is_Proj()) {
915 int opc = current->in(0)->Opcode();
916 if ((final && (opc == Op_MemBarAcquire ||
917 opc == Op_MemBarAcquireLock ||
918 opc == Op_LoadFence)) ||
919 opc == Op_MemBarRelease ||
920 opc == Op_StoreFence ||
921 opc == Op_MemBarReleaseLock ||
922 opc == Op_MemBarStoreStore ||
923 opc == Op_MemBarCPUOrder) {
924 Node* mem = current->in(0)->in(TypeFunc::Memory);
925 if (mem->is_MergeMem()) {
926 MergeMemNode* merge = mem->as_MergeMem();
927 Node* new_st = merge->memory_at(alias_idx);
928 if (new_st == merge->base_memory()) {
929 // Keep searching
930 current = new_st;
931 continue;
932 }
933 // Save the new memory state for the slice and fall through
934 // to exit.
935 result = new_st;
936 }
937 }
938 break;
939 }
940 if (result != NULL) {
941 st = result;
942 }
943 }
944
945 // Loop around twice in the case Load -> Initialize -> Store.
946 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
947 for (int trip = 0; trip <= 1; trip++) {
948
949 if (st->is_Store()) {
950 Node* st_adr = st->in(MemNode::Address);
951 if (!phase->eqv(st_adr, ld_adr)) {
952 // Try harder before giving up... Match raw and non-raw pointers.
953 intptr_t st_off = 0;
954 AllocateNode* alloc = AllocateNode::Ideal_allocation(st_adr, phase, st_off);
955 if (alloc == NULL) return NULL;
956 if (alloc != ld_alloc) return NULL;
957 if (ld_off != st_off) return NULL;
958 // At this point we have proven something like this setup:
959 // A = Allocate(...)
960 // L = LoadQ(, AddP(CastPP(, A.Parm),, #Off))
961 // S = StoreQ(, AddP(, A.Parm , #Off), V)
962 // (Actually, we haven't yet proven the Q's are the same.)
963 // In other words, we are loading from a casted version of
964 // the same pointer-and-offset that we stored to.
965 // Thus, we are able to replace L by V.
966 }
967 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
968 if (store_Opcode() != st->Opcode())
969 return NULL;
970 return st->in(MemNode::ValueIn);
971 }
972
973 // A load from a freshly-created object always returns zero.
974 // (This can happen after LoadNode::Ideal resets the load's memory input
975 // to find_captured_store, which returned InitializeNode::zero_memory.)
976 if (st->is_Proj() && st->in(0)->is_Allocate() &&
977 (st->in(0) == ld_alloc) &&
978 (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) {
979 // return a zero value for the load's basic type
980 // (This is one of the few places where a generic PhaseTransform
981 // can create new nodes. Think of it as lazily manifesting
982 // virtually pre-existing constants.)
983 return phase->zerocon(memory_type());
984 }
985
986 // A load from an initialization barrier can match a captured store.
987 if (st->is_Proj() && st->in(0)->is_Initialize()) {
988 InitializeNode* init = st->in(0)->as_Initialize();
989 AllocateNode* alloc = init->allocation();
990 if ((alloc != NULL) && (alloc == ld_alloc)) {
991 // examine a captured store value
992 st = init->find_captured_store(ld_off, memory_size(), phase);
993 if (st != NULL) {
994 continue; // take one more trip around
995 }
996 }
997 }
998
999 // Load boxed value from result of valueOf() call is input parameter.
1000 if (this->is_Load() && ld_adr->is_AddP() &&
1001 (tp != NULL) && tp->is_ptr_to_boxed_value()) {
1002 intptr_t ignore = 0;
1003 Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore);
1004 base = ShenandoahBarrierNode::skip_through_barrier(base);
1005 if (base != NULL && base->is_Proj() &&
1006 base->as_Proj()->_con == TypeFunc::Parms &&
1007 base->in(0)->is_CallStaticJava() &&
1008 base->in(0)->as_CallStaticJava()->is_boxing_method()) {
1009 return base->in(0)->in(TypeFunc::Parms);
1010 }
1011 }
1012
1013 break;
1014 }
1015
1016 return NULL;
1017 }
1018
1019 //----------------------is_instance_field_load_with_local_phi------------------
1020 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
1021 if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl &&
1022 in(Address)->is_AddP() ) {
1023 const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr();
1024 // Only instances and boxed values.
1025 if( t_oop != NULL &&
1026 (t_oop->is_ptr_to_boxed_value() ||
1027 t_oop->is_known_instance_field()) &&
1028 t_oop->offset() != Type::OffsetBot &&
1029 t_oop->offset() != Type::OffsetTop) {
1030 return true;
1031 }
1032 }
1033 return false;
1034 }
1035
1036 //------------------------------Identity---------------------------------------
1037 // Loads are identity if previous store is to same address
1038 Node *LoadNode::Identity( PhaseTransform *phase ) {
1039 // If the previous store-maker is the right kind of Store, and the store is
1040 // to the same address, then we are equal to the value stored.
1041 Node* mem = in(Memory);
1042 Node* value = can_see_stored_value(mem, phase);
1043 if( value ) {
1044 // byte, short & char stores truncate naturally.
1045 // A load has to load the truncated value which requires
1046 // some sort of masking operation and that requires an
1047 // Ideal call instead of an Identity call.
1048 if (memory_size() < BytesPerInt) {
1049 // If the input to the store does not fit with the load's result type,
1050 // it must be truncated via an Ideal call.
1051 if (!phase->type(value)->higher_equal(phase->type(this)))
1052 return this;
1053 }
1054 // (This works even when value is a Con, but LoadNode::Value
1055 // usually runs first, producing the singleton type of the Con.)
1056 return value;
1057 }
1058
1059 // Search for an existing data phi which was generated before for the same
1060 // instance's field to avoid infinite generation of phis in a loop.
1061 Node *region = mem->in(0);
1062 if (is_instance_field_load_with_local_phi(region)) {
1063 const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr();
1064 int this_index = phase->C->get_alias_index(addr_t);
1065 int this_offset = addr_t->offset();
1066 int this_iid = addr_t->instance_id();
1067 if (!addr_t->is_known_instance() &&
1068 addr_t->is_ptr_to_boxed_value()) {
1069 // Use _idx of address base (could be Phi node) for boxed values.
1070 intptr_t ignore = 0;
1071 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1072 this_iid = base->_idx;
1073 }
1074 const Type* this_type = bottom_type();
1075 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1076 Node* phi = region->fast_out(i);
1077 if (phi->is_Phi() && phi != mem &&
1078 phi->as_Phi()->is_same_inst_field(this_type, this_iid, this_index, this_offset)) {
1079 return phi;
1080 }
1081 }
1082 }
1083
1084 return this;
1085 }
1086
1087 // We're loading from an object which has autobox behaviour.
1088 // If this object is result of a valueOf call we'll have a phi
1089 // merging a newly allocated object and a load from the cache.
1090 // We want to replace this load with the original incoming
1091 // argument to the valueOf call.
1092 Node* LoadNode::eliminate_autobox(PhaseGVN* phase) {
1093 assert(phase->C->eliminate_boxing(), "sanity");
1094 intptr_t ignore = 0;
1095 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1096 if ((base == NULL) || base->is_Phi()) {
1097 // Push the loads from the phi that comes from valueOf up
1098 // through it to allow elimination of the loads and the recovery
1099 // of the original value. It is done in split_through_phi().
1100 return NULL;
1101 } else if (base->is_Load() ||
1102 base->is_DecodeN() && base->in(1)->is_Load()) {
1103 // Eliminate the load of boxed value for integer types from the cache
1104 // array by deriving the value from the index into the array.
1105 // Capture the offset of the load and then reverse the computation.
1106
1107 // Get LoadN node which loads a boxing object from 'cache' array.
1108 if (base->is_DecodeN()) {
1109 base = base->in(1);
1110 }
1111 if (!base->in(Address)->is_AddP()) {
1112 return NULL; // Complex address
1113 }
1114 AddPNode* address = base->in(Address)->as_AddP();
1115 Node* cache_base = address->in(AddPNode::Base);
1116 if ((cache_base != NULL) && cache_base->is_DecodeN()) {
1117 // Get ConP node which is static 'cache' field.
1118 cache_base = cache_base->in(1);
1119 }
1120 if ((cache_base != NULL) && cache_base->is_Con()) {
1121 const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr();
1122 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1123 Node* elements[4];
1124 int shift = exact_log2(type2aelembytes(T_OBJECT));
1125 int count = address->unpack_offsets(elements, ARRAY_SIZE(elements));
1126 if ((count > 0) && elements[0]->is_Con() &&
1127 ((count == 1) ||
1128 (count == 2) && elements[1]->Opcode() == Op_LShiftX &&
1129 elements[1]->in(2) == phase->intcon(shift))) {
1130 ciObjArray* array = base_type->const_oop()->as_obj_array();
1131 // Fetch the box object cache[0] at the base of the array and get its value
1132 ciInstance* box = array->obj_at(0)->as_instance();
1133 ciInstanceKlass* ik = box->klass()->as_instance_klass();
1134 assert(ik->is_box_klass(), "sanity");
1135 assert(ik->nof_nonstatic_fields() == 1, "change following code");
1136 if (ik->nof_nonstatic_fields() == 1) {
1137 // This should be true nonstatic_field_at requires calling
1138 // nof_nonstatic_fields so check it anyway
1139 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1140 BasicType bt = c.basic_type();
1141 // Only integer types have boxing cache.
1142 assert(bt == T_BOOLEAN || bt == T_CHAR ||
1143 bt == T_BYTE || bt == T_SHORT ||
1144 bt == T_INT || bt == T_LONG, err_msg_res("wrong type = %s", type2name(bt)));
1145 jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int();
1146 if (cache_low != (int)cache_low) {
1147 return NULL; // should not happen since cache is array indexed by value
1148 }
1149 jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift);
1150 if (offset != (int)offset) {
1151 return NULL; // should not happen since cache is array indexed by value
1152 }
1153 // Add up all the offsets making of the address of the load
1154 Node* result = elements[0];
1155 for (int i = 1; i < count; i++) {
1156 result = phase->transform(new AddXNode(result, elements[i]));
1157 }
1158 // Remove the constant offset from the address and then
1159 result = phase->transform(new AddXNode(result, phase->MakeConX(-(int)offset)));
1160 // remove the scaling of the offset to recover the original index.
1161 if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) {
1162 // Peel the shift off directly but wrap it in a dummy node
1163 // since Ideal can't return existing nodes
1164 result = new RShiftXNode(result->in(1), phase->intcon(0));
1165 } else if (result->is_Add() && result->in(2)->is_Con() &&
1166 result->in(1)->Opcode() == Op_LShiftX &&
1167 result->in(1)->in(2) == phase->intcon(shift)) {
1168 // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z)
1169 // but for boxing cache access we know that X<<Z will not overflow
1170 // (there is range check) so we do this optimizatrion by hand here.
1171 Node* add_con = new RShiftXNode(result->in(2), phase->intcon(shift));
1172 result = new AddXNode(result->in(1)->in(1), phase->transform(add_con));
1173 } else {
1174 result = new RShiftXNode(result, phase->intcon(shift));
1175 }
1176 #ifdef _LP64
1177 if (bt != T_LONG) {
1178 result = new ConvL2INode(phase->transform(result));
1179 }
1180 #else
1181 if (bt == T_LONG) {
1182 result = new ConvI2LNode(phase->transform(result));
1183 }
1184 #endif
1185 // Boxing/unboxing can be done from signed & unsigned loads (e.g. LoadUB -> ... -> LoadB pair).
1186 // Need to preserve unboxing load type if it is unsigned.
1187 switch(this->Opcode()) {
1188 case Op_LoadUB:
1189 result = new AndINode(phase->transform(result), phase->intcon(0xFF));
1190 break;
1191 case Op_LoadUS:
1192 result = new AndINode(phase->transform(result), phase->intcon(0xFFFF));
1193 break;
1194 }
1195 return result;
1196 }
1197 }
1198 }
1199 }
1200 }
1201 return NULL;
1202 }
1203
1204 static bool stable_phi(PhiNode* phi, PhaseGVN *phase) {
1205 Node* region = phi->in(0);
1206 if (region == NULL) {
1207 return false; // Wait stable graph
1208 }
1209 uint cnt = phi->req();
1210 for (uint i = 1; i < cnt; i++) {
1211 Node* rc = region->in(i);
1212 if (rc == NULL || phase->type(rc) == Type::TOP)
1213 return false; // Wait stable graph
1214 Node* in = phi->in(i);
1215 if (in == NULL || phase->type(in) == Type::TOP)
1216 return false; // Wait stable graph
1217 }
1218 return true;
1219 }
1220 //------------------------------split_through_phi------------------------------
1221 // Split instance or boxed field load through Phi.
1222 Node *LoadNode::split_through_phi(PhaseGVN *phase) {
1223 Node* mem = in(Memory);
1224 Node* address = in(Address);
1225 const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr();
1226
1227 assert((t_oop != NULL) &&
1228 (t_oop->is_known_instance_field() ||
1229 t_oop->is_ptr_to_boxed_value()), "invalide conditions");
1230
1231 Compile* C = phase->C;
1232 intptr_t ignore = 0;
1233 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1234 bool base_is_phi = (base != NULL) && base->is_Phi();
1235 bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() &&
1236 (base != NULL) && (base == address->in(AddPNode::Base)) &&
1237 phase->type(base)->higher_equal(TypePtr::NOTNULL);
1238
1239 if (!((mem->is_Phi() || base_is_phi) &&
1240 (load_boxed_values || t_oop->is_known_instance_field()))) {
1241 return NULL; // memory is not Phi
1242 }
1243
1244 if (mem->is_Phi()) {
1245 if (!stable_phi(mem->as_Phi(), phase)) {
1246 return NULL; // Wait stable graph
1247 }
1248 uint cnt = mem->req();
1249 // Check for loop invariant memory.
1250 if (cnt == 3) {
1251 for (uint i = 1; i < cnt; i++) {
1252 Node* in = mem->in(i);
1253 Node* m = optimize_memory_chain(in, t_oop, this, phase);
1254 if (m == mem) {
1255 set_req(Memory, mem->in(cnt - i));
1256 return this; // made change
1257 }
1258 }
1259 }
1260 }
1261 if (base_is_phi) {
1262 if (!stable_phi(base->as_Phi(), phase)) {
1263 return NULL; // Wait stable graph
1264 }
1265 uint cnt = base->req();
1266 // Check for loop invariant memory.
1267 if (cnt == 3) {
1268 for (uint i = 1; i < cnt; i++) {
1269 if (base->in(i) == base) {
1270 return NULL; // Wait stable graph
1271 }
1272 }
1273 }
1274 }
1275
1276 bool load_boxed_phi = load_boxed_values && base_is_phi && (base->in(0) == mem->in(0));
1277
1278 // Split through Phi (see original code in loopopts.cpp).
1279 assert(C->have_alias_type(t_oop), "instance should have alias type");
1280
1281 // Do nothing here if Identity will find a value
1282 // (to avoid infinite chain of value phis generation).
1283 if (!phase->eqv(this, this->Identity(phase)))
1284 return NULL;
1285
1286 // Select Region to split through.
1287 Node* region;
1288 if (!base_is_phi) {
1289 assert(mem->is_Phi(), "sanity");
1290 region = mem->in(0);
1291 // Skip if the region dominates some control edge of the address.
1292 if (!MemNode::all_controls_dominate(address, region))
1293 return NULL;
1294 } else if (!mem->is_Phi()) {
1295 assert(base_is_phi, "sanity");
1296 region = base->in(0);
1297 // Skip if the region dominates some control edge of the memory.
1298 if (!MemNode::all_controls_dominate(mem, region))
1299 return NULL;
1300 } else if (base->in(0) != mem->in(0)) {
1301 assert(base_is_phi && mem->is_Phi(), "sanity");
1302 if (MemNode::all_controls_dominate(mem, base->in(0))) {
1303 region = base->in(0);
1304 } else if (MemNode::all_controls_dominate(address, mem->in(0))) {
1305 region = mem->in(0);
1306 } else {
1307 return NULL; // complex graph
1308 }
1309 } else {
1310 assert(base->in(0) == mem->in(0), "sanity");
1311 region = mem->in(0);
1312 }
1313
1314 const Type* this_type = this->bottom_type();
1315 int this_index = C->get_alias_index(t_oop);
1316 int this_offset = t_oop->offset();
1317 int this_iid = t_oop->instance_id();
1318 if (!t_oop->is_known_instance() && load_boxed_values) {
1319 // Use _idx of address base for boxed values.
1320 this_iid = base->_idx;
1321 }
1322 PhaseIterGVN* igvn = phase->is_IterGVN();
1323 Node* phi = new PhiNode(region, this_type, NULL, this_iid, this_index, this_offset);
1324 for (uint i = 1; i < region->req(); i++) {
1325 Node* x;
1326 Node* the_clone = NULL;
1327 if (region->in(i) == C->top()) {
1328 x = C->top(); // Dead path? Use a dead data op
1329 } else {
1330 x = this->clone(); // Else clone up the data op
1331 the_clone = x; // Remember for possible deletion.
1332 // Alter data node to use pre-phi inputs
1333 if (this->in(0) == region) {
1334 x->set_req(0, region->in(i));
1335 } else {
1336 x->set_req(0, NULL);
1337 }
1338 if (mem->is_Phi() && (mem->in(0) == region)) {
1339 x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone.
1340 }
1341 if (address->is_Phi() && address->in(0) == region) {
1342 x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone
1343 }
1344 if (base_is_phi && (base->in(0) == region)) {
1345 Node* base_x = base->in(i); // Clone address for loads from boxed objects.
1346 Node* adr_x = phase->transform(new AddPNode(base_x,base_x,address->in(AddPNode::Offset)));
1347 x->set_req(Address, adr_x);
1348 }
1349 }
1350 // Check for a 'win' on some paths
1351 const Type *t = x->Value(igvn);
1352
1353 bool singleton = t->singleton();
1354
1355 // See comments in PhaseIdealLoop::split_thru_phi().
1356 if (singleton && t == Type::TOP) {
1357 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1358 }
1359
1360 if (singleton) {
1361 x = igvn->makecon(t);
1362 } else {
1363 // We now call Identity to try to simplify the cloned node.
1364 // Note that some Identity methods call phase->type(this).
1365 // Make sure that the type array is big enough for
1366 // our new node, even though we may throw the node away.
1367 // (This tweaking with igvn only works because x is a new node.)
1368 igvn->set_type(x, t);
1369 // If x is a TypeNode, capture any more-precise type permanently into Node
1370 // otherwise it will be not updated during igvn->transform since
1371 // igvn->type(x) is set to x->Value() already.
1372 x->raise_bottom_type(t);
1373 Node *y = x->Identity(igvn);
1374 if (y != x) {
1375 x = y;
1376 } else {
1377 y = igvn->hash_find_insert(x);
1378 if (y) {
1379 x = y;
1380 } else {
1381 // Else x is a new node we are keeping
1382 // We do not need register_new_node_with_optimizer
1383 // because set_type has already been called.
1384 igvn->_worklist.push(x);
1385 }
1386 }
1387 }
1388 if (x != the_clone && the_clone != NULL) {
1389 igvn->remove_dead_node(the_clone);
1390 }
1391 phi->set_req(i, x);
1392 }
1393 // Record Phi
1394 igvn->register_new_node_with_optimizer(phi);
1395 return phi;
1396 }
1397
1398 //------------------------------Ideal------------------------------------------
1399 // If the load is from Field memory and the pointer is non-null, it might be possible to
1400 // zero out the control input.
1401 // If the offset is constant and the base is an object allocation,
1402 // try to hook me up to the exact initializing store.
1403 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1404 Node* p = MemNode::Ideal_common(phase, can_reshape);
1405 if (p) return (p == NodeSentinel) ? NULL : p;
1406
1407 Node* ctrl = in(MemNode::Control);
1408 Node* address = in(MemNode::Address);
1409 bool progress = false;
1410
1411 // Skip up past a SafePoint control. Cannot do this for Stores because
1412 // pointer stores & cardmarks must stay on the same side of a SafePoint.
1413 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint &&
1414 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw ) {
1415 ctrl = ctrl->in(0);
1416 set_req(MemNode::Control,ctrl);
1417 progress = true;
1418 }
1419
1420 intptr_t ignore = 0;
1421 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1422 if (base != NULL
1423 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
1424 // Check for useless control edge in some common special cases
1425 if (in(MemNode::Control) != NULL
1426 && can_remove_control()
1427 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1428 && all_controls_dominate(base, phase->C->start())) {
1429 // A method-invariant, non-null address (constant or 'this' argument).
1430 set_req(MemNode::Control, NULL);
1431 progress = true;
1432 }
1433 }
1434
1435 Node* mem = in(MemNode::Memory);
1436 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1437
1438 if (can_reshape && (addr_t != NULL)) {
1439 // try to optimize our memory input
1440 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase);
1441 if (opt_mem != mem) {
1442 set_req(MemNode::Memory, opt_mem);
1443 if (phase->type( opt_mem ) == Type::TOP) return NULL;
1444 return this;
1445 }
1446 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1447 if ((t_oop != NULL) &&
1448 (t_oop->is_known_instance_field() ||
1449 t_oop->is_ptr_to_boxed_value())) {
1450 PhaseIterGVN *igvn = phase->is_IterGVN();
1451 if (igvn != NULL && igvn->_worklist.member(opt_mem)) {
1452 // Delay this transformation until memory Phi is processed.
1453 phase->is_IterGVN()->_worklist.push(this);
1454 return NULL;
1455 }
1456 // Split instance field load through Phi.
1457 Node* result = split_through_phi(phase);
1458 if (result != NULL) return result;
1459
1460 if (t_oop->is_ptr_to_boxed_value()) {
1461 Node* result = eliminate_autobox(phase);
1462 if (result != NULL) return result;
1463 }
1464 }
1465 }
1466
1467 // Is there a dominating load that loads the same value? Leave
1468 // anything that is not a load of a field/array element (like
1469 // barriers etc.) alone
1470 if (in(0) != NULL && adr_type() != TypeRawPtr::BOTTOM && can_reshape) {
1471 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) {
1472 Node *use = mem->fast_out(i);
1473 if (use != this &&
1474 use->Opcode() == Opcode() &&
1475 use->in(0) != NULL &&
1476 use->in(0) != in(0) &&
1477 use->in(Address) == in(Address)) {
1478 Node* ctl = in(0);
1479 for (int i = 0; i < 10 && ctl != NULL; i++) {
1480 ctl = IfNode::up_one_dom(ctl);
1481 if (ctl == use->in(0)) {
1482 set_req(0, use->in(0));
1483 return this;
1484 }
1485 }
1486 }
1487 }
1488 }
1489
1490 // Check for prior store with a different base or offset; make Load
1491 // independent. Skip through any number of them. Bail out if the stores
1492 // are in an endless dead cycle and report no progress. This is a key
1493 // transform for Reflection. However, if after skipping through the Stores
1494 // we can't then fold up against a prior store do NOT do the transform as
1495 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
1496 // array memory alive twice: once for the hoisted Load and again after the
1497 // bypassed Store. This situation only works if EVERYBODY who does
1498 // anti-dependence work knows how to bypass. I.e. we need all
1499 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
1500 // the alias index stuff. So instead, peek through Stores and IFF we can
1501 // fold up, do so.
1502 Node* prev_mem = find_previous_store(phase);
1503 if (prev_mem != NULL) {
1504 Node* value = can_see_arraycopy_value(prev_mem, phase);
1505 if (value != NULL) {
1506 return value;
1507 }
1508 }
1509 // Steps (a), (b): Walk past independent stores to find an exact match.
1510 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) {
1511 // (c) See if we can fold up on the spot, but don't fold up here.
1512 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
1513 // just return a prior value, which is done by Identity calls.
1514 if (can_see_stored_value(prev_mem, phase)) {
1515 // Make ready for step (d):
1516 set_req(MemNode::Memory, prev_mem);
1517 return this;
1518 }
1519 }
1520
1521 return progress ? this : NULL;
1522 }
1523
1524 // Helper to recognize certain Klass fields which are invariant across
1525 // some group of array types (e.g., int[] or all T[] where T < Object).
1526 const Type*
1527 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1528 ciKlass* klass) const {
1529 if (tkls->offset() == in_bytes(Klass::modifier_flags_offset())) {
1530 // The field is Klass::_modifier_flags. Return its (constant) value.
1531 // (Folds up the 2nd indirection in aClassConstant.getModifiers().)
1532 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags");
1533 return TypeInt::make(klass->modifier_flags());
1534 }
1535 if (tkls->offset() == in_bytes(Klass::access_flags_offset())) {
1536 // The field is Klass::_access_flags. Return its (constant) value.
1537 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1538 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags");
1539 return TypeInt::make(klass->access_flags());
1540 }
1541 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) {
1542 // The field is Klass::_layout_helper. Return its constant value if known.
1543 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper");
1544 return TypeInt::make(klass->layout_helper());
1545 }
1546
1547 // No match.
1548 return NULL;
1549 }
1550
1551 // Try to constant-fold a stable array element.
1552 static const Type* fold_stable_ary_elem(const TypeAryPtr* ary, int off, BasicType loadbt) {
1553 assert(ary->const_oop(), "array should be constant");
1554 assert(ary->is_stable(), "array should be stable");
1555
1556 // Decode the results of GraphKit::array_element_address.
1557 ciArray* aobj = ary->const_oop()->as_array();
1558 ciConstant con = aobj->element_value_by_offset(off);
1559
1560 if (con.basic_type() != T_ILLEGAL && !con.is_null_or_zero()) {
1561 const Type* con_type = Type::make_from_constant(con);
1562 if (con_type != NULL) {
1563 if (con_type->isa_aryptr()) {
1564 // Join with the array element type, in case it is also stable.
1565 int dim = ary->stable_dimension();
1566 con_type = con_type->is_aryptr()->cast_to_stable(true, dim-1);
1567 }
1568 if (loadbt == T_NARROWOOP && con_type->isa_oopptr()) {
1569 con_type = con_type->make_narrowoop();
1570 }
1571 #ifndef PRODUCT
1572 if (TraceIterativeGVN) {
1573 tty->print("FoldStableValues: array element [off=%d]: con_type=", off);
1574 con_type->dump(); tty->cr();
1575 }
1576 #endif //PRODUCT
1577 return con_type;
1578 }
1579 }
1580 return NULL;
1581 }
1582
1583 //------------------------------Value-----------------------------------------
1584 const Type *LoadNode::Value( PhaseTransform *phase ) const {
1585 // Either input is TOP ==> the result is TOP
1586 Node* mem = in(MemNode::Memory);
1587 const Type *t1 = phase->type(mem);
1588 if (t1 == Type::TOP) return Type::TOP;
1589 Node* adr = in(MemNode::Address);
1590 const TypePtr* tp = phase->type(adr)->isa_ptr();
1591 if (tp == NULL || tp->empty()) return Type::TOP;
1592 int off = tp->offset();
1593 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
1594 Compile* C = phase->C;
1595
1596 // Try to guess loaded type from pointer type
1597 if (tp->isa_aryptr()) {
1598 const TypeAryPtr* ary = tp->is_aryptr();
1599 const Type* t = ary->elem();
1600
1601 // Determine whether the reference is beyond the header or not, by comparing
1602 // the offset against the offset of the start of the array's data.
1603 // Different array types begin at slightly different offsets (12 vs. 16).
1604 // We choose T_BYTE as an example base type that is least restrictive
1605 // as to alignment, which will therefore produce the smallest
1606 // possible base offset.
1607 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
1608 const bool off_beyond_header = (off != -8 || !UseShenandoahGC) && ((uint)off >= (uint)min_base_off);
1609
1610 // Try to constant-fold a stable array element.
1611 if (FoldStableValues && ary->is_stable() && ary->const_oop() != NULL) {
1612 // Make sure the reference is not into the header and the offset is constant
1613 if (off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) {
1614 const Type* con_type = fold_stable_ary_elem(ary, off, memory_type());
1615 if (con_type != NULL) {
1616 return con_type;
1617 }
1618 }
1619 }
1620
1621 // Don't do this for integer types. There is only potential profit if
1622 // the element type t is lower than _type; that is, for int types, if _type is
1623 // more restrictive than t. This only happens here if one is short and the other
1624 // char (both 16 bits), and in those cases we've made an intentional decision
1625 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
1626 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
1627 //
1628 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
1629 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
1630 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
1631 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
1632 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
1633 // In fact, that could have been the original type of p1, and p1 could have
1634 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
1635 // expression (LShiftL quux 3) independently optimized to the constant 8.
1636 if ((t->isa_int() == NULL) && (t->isa_long() == NULL)
1637 && (_type->isa_vect() == NULL)
1638 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
1639 // t might actually be lower than _type, if _type is a unique
1640 // concrete subclass of abstract class t.
1641 if (off_beyond_header) { // is the offset beyond the header?
1642 const Type* jt = t->join_speculative(_type);
1643 // In any case, do not allow the join, per se, to empty out the type.
1644 if (jt->empty() && !t->empty()) {
1645 // This can happen if a interface-typed array narrows to a class type.
1646 jt = _type;
1647 }
1648 #ifdef ASSERT
1649 if (phase->C->eliminate_boxing() && adr->is_AddP()) {
1650 // The pointers in the autobox arrays are always non-null
1651 Node* base = adr->in(AddPNode::Base);
1652 if ((base != NULL) && base->is_DecodeN()) {
1653 // Get LoadN node which loads IntegerCache.cache field
1654 base = base->in(1);
1655 }
1656 if ((base != NULL) && base->is_Con()) {
1657 const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr();
1658 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1659 // It could be narrow oop
1660 assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity");
1661 }
1662 }
1663 }
1664 #endif
1665 return jt;
1666 }
1667 }
1668 } else if (tp->base() == Type::InstPtr) {
1669 ciEnv* env = C->env();
1670 const TypeInstPtr* tinst = tp->is_instptr();
1671 ciKlass* klass = tinst->klass();
1672 assert( off != Type::OffsetBot ||
1673 // arrays can be cast to Objects
1674 tp->is_oopptr()->klass()->is_java_lang_Object() ||
1675 // unsafe field access may not have a constant offset
1676 C->has_unsafe_access(),
1677 "Field accesses must be precise" );
1678 // For oop loads, we expect the _type to be precise
1679 if (klass == env->String_klass() &&
1680 adr->is_AddP() && off != Type::OffsetBot) {
1681 // For constant Strings treat the final fields as compile time constants.
1682 // While we can list what field types java.lang.String has, it is more
1683 // future-proof to handle all possible field types, anticipating future
1684 // changes and experiments in String code.
1685 Node* base = adr->in(AddPNode::Base);
1686 const TypeOopPtr* t = phase->type(base)->isa_oopptr();
1687 if (t != NULL && t->singleton()) {
1688 ciField* field = env->String_klass()->get_field_by_offset(off, false);
1689 if (field != NULL && field->is_final()) {
1690 ciObject* string = t->const_oop();
1691 ciConstant constant = string->as_instance()->field_value(field);
1692 // Type::make_from_constant does not handle narrow oops, so handle it here.
1693 // Everything else can use the factory method.
1694 if ((constant.basic_type() == T_ARRAY || constant.basic_type() == T_OBJECT)
1695 && adr->bottom_type()->is_ptr_to_narrowoop()) {
1696 return TypeNarrowOop::make_from_constant(constant.as_object(), true);
1697 } else {
1698 return Type::make_from_constant(constant, true);
1699 }
1700 }
1701 }
1702 }
1703 // Optimizations for constant objects
1704 ciObject* const_oop = tinst->const_oop();
1705 if (const_oop != NULL) {
1706 // For constant Boxed value treat the target field as a compile time constant.
1707 if (tinst->is_ptr_to_boxed_value()) {
1708 return tinst->get_const_boxed_value();
1709 } else
1710 // For constant CallSites treat the target field as a compile time constant.
1711 if (const_oop->is_call_site()) {
1712 ciCallSite* call_site = const_oop->as_call_site();
1713 ciField* field = call_site->klass()->as_instance_klass()->get_field_by_offset(off, /*is_static=*/ false);
1714 if (field != NULL && field->is_call_site_target()) {
1715 ciMethodHandle* target = call_site->get_target();
1716 if (target != NULL) { // just in case
1717 ciConstant constant(T_OBJECT, target);
1718 const Type* t;
1719 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
1720 t = TypeNarrowOop::make_from_constant(constant.as_object(), true);
1721 } else {
1722 t = TypeOopPtr::make_from_constant(constant.as_object(), true);
1723 }
1724 // Add a dependence for invalidation of the optimization.
1725 if (!call_site->is_constant_call_site()) {
1726 C->dependencies()->assert_call_site_target_value(call_site, target);
1727 }
1728 return t;
1729 }
1730 }
1731 }
1732 }
1733 } else if (tp->base() == Type::KlassPtr) {
1734 assert( off != Type::OffsetBot ||
1735 // arrays can be cast to Objects
1736 tp->is_klassptr()->klass()->is_java_lang_Object() ||
1737 // also allow array-loading from the primary supertype
1738 // array during subtype checks
1739 Opcode() == Op_LoadKlass,
1740 "Field accesses must be precise" );
1741 // For klass/static loads, we expect the _type to be precise
1742 }
1743
1744 const TypeKlassPtr *tkls = tp->isa_klassptr();
1745 if (tkls != NULL && !StressReflectiveCode) {
1746 ciKlass* klass = tkls->klass();
1747 if (klass->is_loaded() && tkls->klass_is_exact()) {
1748 // We are loading a field from a Klass metaobject whose identity
1749 // is known at compile time (the type is "exact" or "precise").
1750 // Check for fields we know are maintained as constants by the VM.
1751 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) {
1752 // The field is Klass::_super_check_offset. Return its (constant) value.
1753 // (Folds up type checking code.)
1754 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
1755 return TypeInt::make(klass->super_check_offset());
1756 }
1757 // Compute index into primary_supers array
1758 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1759 // Check for overflowing; use unsigned compare to handle the negative case.
1760 if( depth < ciKlass::primary_super_limit() ) {
1761 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1762 // (Folds up type checking code.)
1763 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1764 ciKlass *ss = klass->super_of_depth(depth);
1765 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1766 }
1767 const Type* aift = load_array_final_field(tkls, klass);
1768 if (aift != NULL) return aift;
1769 if (tkls->offset() == in_bytes(Klass::java_mirror_offset())) {
1770 // The field is Klass::_java_mirror. Return its (constant) value.
1771 // (Folds up the 2nd indirection in anObjConstant.getClass().)
1772 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
1773 return TypeInstPtr::make(klass->java_mirror());
1774 }
1775 }
1776
1777 // We can still check if we are loading from the primary_supers array at a
1778 // shallow enough depth. Even though the klass is not exact, entries less
1779 // than or equal to its super depth are correct.
1780 if (klass->is_loaded() ) {
1781 ciType *inner = klass;
1782 while( inner->is_obj_array_klass() )
1783 inner = inner->as_obj_array_klass()->base_element_type();
1784 if( inner->is_instance_klass() &&
1785 !inner->as_instance_klass()->flags().is_interface() ) {
1786 // Compute index into primary_supers array
1787 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1788 // Check for overflowing; use unsigned compare to handle the negative case.
1789 if( depth < ciKlass::primary_super_limit() &&
1790 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case
1791 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1792 // (Folds up type checking code.)
1793 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1794 ciKlass *ss = klass->super_of_depth(depth);
1795 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1796 }
1797 }
1798 }
1799
1800 // If the type is enough to determine that the thing is not an array,
1801 // we can give the layout_helper a positive interval type.
1802 // This will help short-circuit some reflective code.
1803 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())
1804 && !klass->is_array_klass() // not directly typed as an array
1805 && !klass->is_interface() // specifically not Serializable & Cloneable
1806 && !klass->is_java_lang_Object() // not the supertype of all T[]
1807 ) {
1808 // Note: When interfaces are reliable, we can narrow the interface
1809 // test to (klass != Serializable && klass != Cloneable).
1810 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
1811 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
1812 // The key property of this type is that it folds up tests
1813 // for array-ness, since it proves that the layout_helper is positive.
1814 // Thus, a generic value like the basic object layout helper works fine.
1815 return TypeInt::make(min_size, max_jint, Type::WidenMin);
1816 }
1817 }
1818
1819 // If we are loading from a freshly-allocated object, produce a zero,
1820 // if the load is provably beyond the header of the object.
1821 // (Also allow a variable load from a fresh array to produce zero.)
1822 const TypeOopPtr *tinst = tp->isa_oopptr();
1823 bool is_instance = (tinst != NULL) && tinst->is_known_instance_field();
1824 bool is_boxed_value = (tinst != NULL) && tinst->is_ptr_to_boxed_value();
1825 if (ReduceFieldZeroing || is_instance || is_boxed_value) {
1826 Node* value = can_see_stored_value(mem,phase);
1827 if (value != NULL && value->is_Con()) {
1828 assert(value->bottom_type()->higher_equal(_type),"sanity");
1829 return value->bottom_type();
1830 }
1831 }
1832
1833 if (is_instance) {
1834 // If we have an instance type and our memory input is the
1835 // programs's initial memory state, there is no matching store,
1836 // so just return a zero of the appropriate type
1837 Node *mem = in(MemNode::Memory);
1838 if (mem->is_Parm() && mem->in(0)->is_Start()) {
1839 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
1840 return Type::get_zero_type(_type->basic_type());
1841 }
1842 }
1843 return _type;
1844 }
1845
1846 //------------------------------match_edge-------------------------------------
1847 // Do we Match on this edge index or not? Match only the address.
1848 uint LoadNode::match_edge(uint idx) const {
1849 return idx == MemNode::Address;
1850 }
1851
1852 //--------------------------LoadBNode::Ideal--------------------------------------
1853 //
1854 // If the previous store is to the same address as this load,
1855 // and the value stored was larger than a byte, replace this load
1856 // with the value stored truncated to a byte. If no truncation is
1857 // needed, the replacement is done in LoadNode::Identity().
1858 //
1859 Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1860 Node* mem = in(MemNode::Memory);
1861 Node* value = can_see_stored_value(mem,phase);
1862 if( value && !phase->type(value)->higher_equal( _type ) ) {
1863 Node *result = phase->transform( new LShiftINode(value, phase->intcon(24)) );
1864 return new RShiftINode(result, phase->intcon(24));
1865 }
1866 // Identity call will handle the case where truncation is not needed.
1867 return LoadNode::Ideal(phase, can_reshape);
1868 }
1869
1870 const Type* LoadBNode::Value(PhaseTransform *phase) const {
1871 Node* mem = in(MemNode::Memory);
1872 Node* value = can_see_stored_value(mem,phase);
1873 if (value != NULL && value->is_Con() &&
1874 !value->bottom_type()->higher_equal(_type)) {
1875 // If the input to the store does not fit with the load's result type,
1876 // it must be truncated. We can't delay until Ideal call since
1877 // a singleton Value is needed for split_thru_phi optimization.
1878 int con = value->get_int();
1879 return TypeInt::make((con << 24) >> 24);
1880 }
1881 return LoadNode::Value(phase);
1882 }
1883
1884 //--------------------------LoadUBNode::Ideal-------------------------------------
1885 //
1886 // If the previous store is to the same address as this load,
1887 // and the value stored was larger than a byte, replace this load
1888 // with the value stored truncated to a byte. If no truncation is
1889 // needed, the replacement is done in LoadNode::Identity().
1890 //
1891 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
1892 Node* mem = in(MemNode::Memory);
1893 Node* value = can_see_stored_value(mem, phase);
1894 if (value && !phase->type(value)->higher_equal(_type))
1895 return new AndINode(value, phase->intcon(0xFF));
1896 // Identity call will handle the case where truncation is not needed.
1897 return LoadNode::Ideal(phase, can_reshape);
1898 }
1899
1900 const Type* LoadUBNode::Value(PhaseTransform *phase) const {
1901 Node* mem = in(MemNode::Memory);
1902 Node* value = can_see_stored_value(mem,phase);
1903 if (value != NULL && value->is_Con() &&
1904 !value->bottom_type()->higher_equal(_type)) {
1905 // If the input to the store does not fit with the load's result type,
1906 // it must be truncated. We can't delay until Ideal call since
1907 // a singleton Value is needed for split_thru_phi optimization.
1908 int con = value->get_int();
1909 return TypeInt::make(con & 0xFF);
1910 }
1911 return LoadNode::Value(phase);
1912 }
1913
1914 //--------------------------LoadUSNode::Ideal-------------------------------------
1915 //
1916 // If the previous store is to the same address as this load,
1917 // and the value stored was larger than a char, replace this load
1918 // with the value stored truncated to a char. If no truncation is
1919 // needed, the replacement is done in LoadNode::Identity().
1920 //
1921 Node *LoadUSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1922 Node* mem = in(MemNode::Memory);
1923 Node* value = can_see_stored_value(mem,phase);
1924 if( value && !phase->type(value)->higher_equal( _type ) )
1925 return new AndINode(value,phase->intcon(0xFFFF));
1926 // Identity call will handle the case where truncation is not needed.
1927 return LoadNode::Ideal(phase, can_reshape);
1928 }
1929
1930 const Type* LoadUSNode::Value(PhaseTransform *phase) const {
1931 Node* mem = in(MemNode::Memory);
1932 Node* value = can_see_stored_value(mem,phase);
1933 if (value != NULL && value->is_Con() &&
1934 !value->bottom_type()->higher_equal(_type)) {
1935 // If the input to the store does not fit with the load's result type,
1936 // it must be truncated. We can't delay until Ideal call since
1937 // a singleton Value is needed for split_thru_phi optimization.
1938 int con = value->get_int();
1939 return TypeInt::make(con & 0xFFFF);
1940 }
1941 return LoadNode::Value(phase);
1942 }
1943
1944 //--------------------------LoadSNode::Ideal--------------------------------------
1945 //
1946 // If the previous store is to the same address as this load,
1947 // and the value stored was larger than a short, replace this load
1948 // with the value stored truncated to a short. If no truncation is
1949 // needed, the replacement is done in LoadNode::Identity().
1950 //
1951 Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1952 Node* mem = in(MemNode::Memory);
1953 Node* value = can_see_stored_value(mem,phase);
1954 if( value && !phase->type(value)->higher_equal( _type ) ) {
1955 Node *result = phase->transform( new LShiftINode(value, phase->intcon(16)) );
1956 return new RShiftINode(result, phase->intcon(16));
1957 }
1958 // Identity call will handle the case where truncation is not needed.
1959 return LoadNode::Ideal(phase, can_reshape);
1960 }
1961
1962 const Type* LoadSNode::Value(PhaseTransform *phase) const {
1963 Node* mem = in(MemNode::Memory);
1964 Node* value = can_see_stored_value(mem,phase);
1965 if (value != NULL && value->is_Con() &&
1966 !value->bottom_type()->higher_equal(_type)) {
1967 // If the input to the store does not fit with the load's result type,
1968 // it must be truncated. We can't delay until Ideal call since
1969 // a singleton Value is needed for split_thru_phi optimization.
1970 int con = value->get_int();
1971 return TypeInt::make((con << 16) >> 16);
1972 }
1973 return LoadNode::Value(phase);
1974 }
1975
1976 //=============================================================================
1977 //----------------------------LoadKlassNode::make------------------------------
1978 // Polymorphic factory method:
1979 Node* LoadKlassNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* at, const TypeKlassPtr* tk) {
1980 // sanity check the alias category against the created node type
1981 const TypePtr *adr_type = adr->bottom_type()->isa_ptr();
1982 assert(adr_type != NULL, "expecting TypeKlassPtr");
1983 #ifdef _LP64
1984 if (adr_type->is_ptr_to_narrowklass()) {
1985 assert(UseCompressedClassPointers, "no compressed klasses");
1986 Node* load_klass = gvn.transform(new LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowklass(), MemNode::unordered));
1987 return new DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr());
1988 }
1989 #endif
1990 assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
1991 return new LoadKlassNode(ctl, mem, adr, at, tk, MemNode::unordered);
1992 }
1993
1994 //------------------------------Value------------------------------------------
1995 const Type *LoadKlassNode::Value( PhaseTransform *phase ) const {
1996 return klass_value_common(phase);
1997 }
1998
1999 // In most cases, LoadKlassNode does not have the control input set. If the control
2000 // input is set, it must not be removed (by LoadNode::Ideal()).
2001 bool LoadKlassNode::can_remove_control() const {
2002 return false;
2003 }
2004
2005 const Type *LoadNode::klass_value_common( PhaseTransform *phase ) const {
2006 // Either input is TOP ==> the result is TOP
2007 const Type *t1 = phase->type( in(MemNode::Memory) );
2008 if (t1 == Type::TOP) return Type::TOP;
2009 Node *adr = in(MemNode::Address);
2010 const Type *t2 = phase->type( adr );
2011 if (t2 == Type::TOP) return Type::TOP;
2012 const TypePtr *tp = t2->is_ptr();
2013 if (TypePtr::above_centerline(tp->ptr()) ||
2014 tp->ptr() == TypePtr::Null) return Type::TOP;
2015
2016 // Return a more precise klass, if possible
2017 const TypeInstPtr *tinst = tp->isa_instptr();
2018 if (tinst != NULL) {
2019 ciInstanceKlass* ik = tinst->klass()->as_instance_klass();
2020 int offset = tinst->offset();
2021 if (ik == phase->C->env()->Class_klass()
2022 && (offset == java_lang_Class::klass_offset_in_bytes() ||
2023 offset == java_lang_Class::array_klass_offset_in_bytes())) {
2024 // We are loading a special hidden field from a Class mirror object,
2025 // the field which points to the VM's Klass metaobject.
2026 ciType* t = tinst->java_mirror_type();
2027 // java_mirror_type returns non-null for compile-time Class constants.
2028 if (t != NULL) {
2029 // constant oop => constant klass
2030 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
2031 if (t->is_void()) {
2032 // We cannot create a void array. Since void is a primitive type return null
2033 // klass. Users of this result need to do a null check on the returned klass.
2034 return TypePtr::NULL_PTR;
2035 }
2036 return TypeKlassPtr::make(ciArrayKlass::make(t));
2037 }
2038 if (!t->is_klass()) {
2039 // a primitive Class (e.g., int.class) has NULL for a klass field
2040 return TypePtr::NULL_PTR;
2041 }
2042 // (Folds up the 1st indirection in aClassConstant.getModifiers().)
2043 return TypeKlassPtr::make(t->as_klass());
2044 }
2045 // non-constant mirror, so we can't tell what's going on
2046 }
2047 if( !ik->is_loaded() )
2048 return _type; // Bail out if not loaded
2049 if (offset == oopDesc::klass_offset_in_bytes()) {
2050 if (tinst->klass_is_exact()) {
2051 return TypeKlassPtr::make(ik);
2052 }
2053 // See if we can become precise: no subklasses and no interface
2054 // (Note: We need to support verified interfaces.)
2055 if (!ik->is_interface() && !ik->has_subklass()) {
2056 //assert(!UseExactTypes, "this code should be useless with exact types");
2057 // Add a dependence; if any subclass added we need to recompile
2058 if (!ik->is_final()) {
2059 // %%% should use stronger assert_unique_concrete_subtype instead
2060 phase->C->dependencies()->assert_leaf_type(ik);
2061 }
2062 // Return precise klass
2063 return TypeKlassPtr::make(ik);
2064 }
2065
2066 // Return root of possible klass
2067 return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/);
2068 }
2069 }
2070
2071 // Check for loading klass from an array
2072 const TypeAryPtr *tary = tp->isa_aryptr();
2073 if( tary != NULL ) {
2074 ciKlass *tary_klass = tary->klass();
2075 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP
2076 && tary->offset() == oopDesc::klass_offset_in_bytes()) {
2077 if (tary->klass_is_exact()) {
2078 return TypeKlassPtr::make(tary_klass);
2079 }
2080 ciArrayKlass *ak = tary->klass()->as_array_klass();
2081 // If the klass is an object array, we defer the question to the
2082 // array component klass.
2083 if( ak->is_obj_array_klass() ) {
2084 assert( ak->is_loaded(), "" );
2085 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass();
2086 if( base_k->is_loaded() && base_k->is_instance_klass() ) {
2087 ciInstanceKlass* ik = base_k->as_instance_klass();
2088 // See if we can become precise: no subklasses and no interface
2089 if (!ik->is_interface() && !ik->has_subklass()) {
2090 //assert(!UseExactTypes, "this code should be useless with exact types");
2091 // Add a dependence; if any subclass added we need to recompile
2092 if (!ik->is_final()) {
2093 phase->C->dependencies()->assert_leaf_type(ik);
2094 }
2095 // Return precise array klass
2096 return TypeKlassPtr::make(ak);
2097 }
2098 }
2099 return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/);
2100 } else { // Found a type-array?
2101 //assert(!UseExactTypes, "this code should be useless with exact types");
2102 assert( ak->is_type_array_klass(), "" );
2103 return TypeKlassPtr::make(ak); // These are always precise
2104 }
2105 }
2106 }
2107
2108 // Check for loading klass from an array klass
2109 const TypeKlassPtr *tkls = tp->isa_klassptr();
2110 if (tkls != NULL && !StressReflectiveCode) {
2111 ciKlass* klass = tkls->klass();
2112 if( !klass->is_loaded() )
2113 return _type; // Bail out if not loaded
2114 if( klass->is_obj_array_klass() &&
2115 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) {
2116 ciKlass* elem = klass->as_obj_array_klass()->element_klass();
2117 // // Always returning precise element type is incorrect,
2118 // // e.g., element type could be object and array may contain strings
2119 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
2120
2121 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
2122 // according to the element type's subclassing.
2123 return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/);
2124 }
2125 if( klass->is_instance_klass() && tkls->klass_is_exact() &&
2126 tkls->offset() == in_bytes(Klass::super_offset())) {
2127 ciKlass* sup = klass->as_instance_klass()->super();
2128 // The field is Klass::_super. Return its (constant) value.
2129 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
2130 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR;
2131 }
2132 }
2133
2134 // Bailout case
2135 return LoadNode::Value(phase);
2136 }
2137
2138 //------------------------------Identity---------------------------------------
2139 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
2140 // Also feed through the klass in Allocate(...klass...)._klass.
2141 Node* LoadKlassNode::Identity( PhaseTransform *phase ) {
2142 return klass_identity_common(phase);
2143 }
2144
2145 Node* LoadNode::klass_identity_common(PhaseTransform *phase ) {
2146 Node* x = LoadNode::Identity(phase);
2147 if (x != this) return x;
2148
2149 // Take apart the address into an oop and and offset.
2150 // Return 'this' if we cannot.
2151 Node* adr = in(MemNode::Address);
2152 intptr_t offset = 0;
2153 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2154 if (base == NULL) return this;
2155 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
2156 if (toop == NULL) return this;
2157
2158 // We can fetch the klass directly through an AllocateNode.
2159 // This works even if the klass is not constant (clone or newArray).
2160 if (offset == oopDesc::klass_offset_in_bytes()) {
2161 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
2162 if (allocated_klass != NULL) {
2163 return allocated_klass;
2164 }
2165 }
2166
2167 // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*.
2168 // See inline_native_Class_query for occurrences of these patterns.
2169 // Java Example: x.getClass().isAssignableFrom(y)
2170 //
2171 // This improves reflective code, often making the Class
2172 // mirror go completely dead. (Current exception: Class
2173 // mirrors may appear in debug info, but we could clean them out by
2174 // introducing a new debug info operator for Klass*.java_mirror).
2175 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass()
2176 && offset == java_lang_Class::klass_offset_in_bytes()) {
2177 // We are loading a special hidden field from a Class mirror,
2178 // the field which points to its Klass or ArrayKlass metaobject.
2179 if (base->is_Load()) {
2180 Node* adr2 = base->in(MemNode::Address);
2181 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2182 if (tkls != NULL && !tkls->empty()
2183 && (tkls->klass()->is_instance_klass() ||
2184 tkls->klass()->is_array_klass())
2185 && adr2->is_AddP()
2186 ) {
2187 int mirror_field = in_bytes(Klass::java_mirror_offset());
2188 if (tkls->offset() == mirror_field) {
2189 return adr2->in(AddPNode::Base);
2190 }
2191 }
2192 }
2193 }
2194
2195 return this;
2196 }
2197
2198
2199 //------------------------------Value------------------------------------------
2200 const Type *LoadNKlassNode::Value( PhaseTransform *phase ) const {
2201 const Type *t = klass_value_common(phase);
2202 if (t == Type::TOP)
2203 return t;
2204
2205 return t->make_narrowklass();
2206 }
2207
2208 //------------------------------Identity---------------------------------------
2209 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
2210 // Also feed through the klass in Allocate(...klass...)._klass.
2211 Node* LoadNKlassNode::Identity( PhaseTransform *phase ) {
2212 Node *x = klass_identity_common(phase);
2213
2214 const Type *t = phase->type( x );
2215 if( t == Type::TOP ) return x;
2216 if( t->isa_narrowklass()) return x;
2217 assert (!t->isa_narrowoop(), "no narrow oop here");
2218
2219 return phase->transform(new EncodePKlassNode(x, t->make_narrowklass()));
2220 }
2221
2222 //------------------------------Value-----------------------------------------
2223 const Type *LoadRangeNode::Value( PhaseTransform *phase ) const {
2224 // Either input is TOP ==> the result is TOP
2225 const Type *t1 = phase->type( in(MemNode::Memory) );
2226 if( t1 == Type::TOP ) return Type::TOP;
2227 Node *adr = in(MemNode::Address);
2228 const Type *t2 = phase->type( adr );
2229 if( t2 == Type::TOP ) return Type::TOP;
2230 const TypePtr *tp = t2->is_ptr();
2231 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
2232 const TypeAryPtr *tap = tp->isa_aryptr();
2233 if( !tap ) return _type;
2234 return tap->size();
2235 }
2236
2237 //-------------------------------Ideal---------------------------------------
2238 // Feed through the length in AllocateArray(...length...)._length.
2239 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2240 Node* p = MemNode::Ideal_common(phase, can_reshape);
2241 if (p) return (p == NodeSentinel) ? NULL : p;
2242
2243 // Take apart the address into an oop and and offset.
2244 // Return 'this' if we cannot.
2245 Node* adr = in(MemNode::Address);
2246 intptr_t offset = 0;
2247 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2248 if (base == NULL) return NULL;
2249 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2250 if (tary == NULL) return NULL;
2251
2252 // We can fetch the length directly through an AllocateArrayNode.
2253 // This works even if the length is not constant (clone or newArray).
2254 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2255 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2256 if (alloc != NULL) {
2257 Node* allocated_length = alloc->Ideal_length();
2258 Node* len = alloc->make_ideal_length(tary, phase);
2259 if (allocated_length != len) {
2260 // New CastII improves on this.
2261 return len;
2262 }
2263 }
2264 }
2265
2266 return NULL;
2267 }
2268
2269 //------------------------------Identity---------------------------------------
2270 // Feed through the length in AllocateArray(...length...)._length.
2271 Node* LoadRangeNode::Identity( PhaseTransform *phase ) {
2272 Node* x = LoadINode::Identity(phase);
2273 if (x != this) return x;
2274
2275 // Take apart the address into an oop and and offset.
2276 // Return 'this' if we cannot.
2277 Node* adr = in(MemNode::Address);
2278 intptr_t offset = 0;
2279 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2280 if (base == NULL) return this;
2281 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2282 if (tary == NULL) return this;
2283
2284 // We can fetch the length directly through an AllocateArrayNode.
2285 // This works even if the length is not constant (clone or newArray).
2286 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2287 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2288 if (alloc != NULL) {
2289 Node* allocated_length = alloc->Ideal_length();
2290 // Do not allow make_ideal_length to allocate a CastII node.
2291 Node* len = alloc->make_ideal_length(tary, phase, false);
2292 if (allocated_length == len) {
2293 // Return allocated_length only if it would not be improved by a CastII.
2294 return allocated_length;
2295 }
2296 }
2297 }
2298
2299 return this;
2300
2301 }
2302
2303 //=============================================================================
2304 //---------------------------StoreNode::make-----------------------------------
2305 // Polymorphic factory method:
2306 StoreNode* StoreNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt, MemOrd mo) {
2307 assert((mo == unordered || mo == release), "unexpected");
2308 Compile* C = gvn.C;
2309 assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2310 ctl != NULL, "raw memory operations should have control edge");
2311
2312 switch (bt) {
2313 case T_BOOLEAN:
2314 case T_BYTE: return new StoreBNode(ctl, mem, adr, adr_type, val, mo);
2315 case T_INT: return new StoreINode(ctl, mem, adr, adr_type, val, mo);
2316 case T_CHAR:
2317 case T_SHORT: return new StoreCNode(ctl, mem, adr, adr_type, val, mo);
2318 case T_LONG: return new StoreLNode(ctl, mem, adr, adr_type, val, mo);
2319 case T_FLOAT: return new StoreFNode(ctl, mem, adr, adr_type, val, mo);
2320 case T_DOUBLE: return new StoreDNode(ctl, mem, adr, adr_type, val, mo);
2321 case T_METADATA:
2322 case T_ADDRESS:
2323 case T_OBJECT:
2324 #ifdef _LP64
2325 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
2326 val = gvn.transform(new EncodePNode(val, val->bottom_type()->make_narrowoop()));
2327 return new StoreNNode(ctl, mem, adr, adr_type, val, mo);
2328 } else if (adr->bottom_type()->is_ptr_to_narrowklass() ||
2329 (UseCompressedClassPointers && val->bottom_type()->isa_klassptr() &&
2330 adr->bottom_type()->isa_rawptr())) {
2331 val = gvn.transform(new EncodePKlassNode(val, val->bottom_type()->make_narrowklass()));
2332 return new StoreNKlassNode(ctl, mem, adr, adr_type, val, mo);
2333 }
2334 #endif
2335 {
2336 return new StorePNode(ctl, mem, adr, adr_type, val, mo);
2337 }
2338 }
2339 ShouldNotReachHere();
2340 return (StoreNode*)NULL;
2341 }
2342
2343 StoreLNode* StoreLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
2344 bool require_atomic = true;
2345 return new StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
2346 }
2347
2348 StoreDNode* StoreDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
2349 bool require_atomic = true;
2350 return new StoreDNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
2351 }
2352
2353
2354 //--------------------------bottom_type----------------------------------------
2355 const Type *StoreNode::bottom_type() const {
2356 return Type::MEMORY;
2357 }
2358
2359 //------------------------------hash-------------------------------------------
2360 uint StoreNode::hash() const {
2361 // unroll addition of interesting fields
2362 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2363
2364 // Since they are not commoned, do not hash them:
2365 return NO_HASH;
2366 }
2367
2368 //------------------------------Ideal------------------------------------------
2369 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
2370 // When a store immediately follows a relevant allocation/initialization,
2371 // try to capture it into the initialization, or hoist it above.
2372 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2373 Node* p = MemNode::Ideal_common(phase, can_reshape);
2374 if (p) return (p == NodeSentinel) ? NULL : p;
2375
2376 Node* mem = in(MemNode::Memory);
2377 Node* address = in(MemNode::Address);
2378 // Back-to-back stores to same address? Fold em up. Generally
2379 // unsafe if I have intervening uses... Also disallowed for StoreCM
2380 // since they must follow each StoreP operation. Redundant StoreCMs
2381 // are eliminated just before matching in final_graph_reshape.
2382 {
2383 Node* st = mem;
2384 // If Store 'st' has more than one use, we cannot fold 'st' away.
2385 // For example, 'st' might be the final state at a conditional
2386 // return. Or, 'st' might be used by some node which is live at
2387 // the same time 'st' is live, which might be unschedulable. So,
2388 // require exactly ONE user until such time as we clone 'mem' for
2389 // each of 'mem's uses (thus making the exactly-1-user-rule hold
2390 // true).
2391 while (st->is_Store() && st->outcnt() == 1 && st->Opcode() != Op_StoreCM) {
2392 // Looking at a dead closed cycle of memory?
2393 assert(st != st->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
2394 assert(Opcode() == st->Opcode() ||
2395 st->Opcode() == Op_StoreVector ||
2396 Opcode() == Op_StoreVector ||
2397 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw ||
2398 (Opcode() == Op_StoreL && st->Opcode() == Op_StoreI), // expanded ClearArrayNode
2399 err_msg_res("no mismatched stores, except on raw memory: %s %s", NodeClassNames[Opcode()], NodeClassNames[st->Opcode()]));
2400
2401 if (st->in(MemNode::Address)->eqv_uncast(address) &&
2402 st->as_Store()->memory_size() <= this->memory_size()) {
2403 Node* use = st->raw_out(0);
2404 phase->igvn_rehash_node_delayed(use);
2405 if (can_reshape) {
2406 use->set_req_X(MemNode::Memory, st->in(MemNode::Memory), phase->is_IterGVN());
2407 } else {
2408 // It's OK to do this in the parser, since DU info is always accurate,
2409 // and the parser always refers to nodes via SafePointNode maps.
2410 use->set_req(MemNode::Memory, st->in(MemNode::Memory));
2411 }
2412 return this;
2413 }
2414 st = st->in(MemNode::Memory);
2415 }
2416 }
2417
2418
2419 // Capture an unaliased, unconditional, simple store into an initializer.
2420 // Or, if it is independent of the allocation, hoist it above the allocation.
2421 if (ReduceFieldZeroing && /*can_reshape &&*/
2422 mem->is_Proj() && mem->in(0)->is_Initialize()) {
2423 InitializeNode* init = mem->in(0)->as_Initialize();
2424 intptr_t offset = init->can_capture_store(this, phase, can_reshape);
2425 if (offset > 0) {
2426 Node* moved = init->capture_store(this, offset, phase, can_reshape);
2427 // If the InitializeNode captured me, it made a raw copy of me,
2428 // and I need to disappear.
2429 if (moved != NULL) {
2430 // %%% hack to ensure that Ideal returns a new node:
2431 mem = MergeMemNode::make(mem);
2432 return mem; // fold me away
2433 }
2434 }
2435 }
2436
2437 return NULL; // No further progress
2438 }
2439
2440 //------------------------------Value-----------------------------------------
2441 const Type *StoreNode::Value( PhaseTransform *phase ) const {
2442 // Either input is TOP ==> the result is TOP
2443 const Type *t1 = phase->type( in(MemNode::Memory) );
2444 if( t1 == Type::TOP ) return Type::TOP;
2445 const Type *t2 = phase->type( in(MemNode::Address) );
2446 if( t2 == Type::TOP ) return Type::TOP;
2447 const Type *t3 = phase->type( in(MemNode::ValueIn) );
2448 if( t3 == Type::TOP ) return Type::TOP;
2449 return Type::MEMORY;
2450 }
2451
2452 //------------------------------Identity---------------------------------------
2453 // Remove redundant stores:
2454 // Store(m, p, Load(m, p)) changes to m.
2455 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
2456 Node *StoreNode::Identity( PhaseTransform *phase ) {
2457 Node* mem = in(MemNode::Memory);
2458 Node* adr = in(MemNode::Address);
2459 Node* val = in(MemNode::ValueIn);
2460
2461 // Load then Store? Then the Store is useless
2462 if (val->is_Load() &&
2463 val->in(MemNode::Address)->eqv_uncast(adr) &&
2464 val->in(MemNode::Memory )->eqv_uncast(mem) &&
2465 val->as_Load()->store_Opcode() == Opcode()) {
2466 return mem;
2467 }
2468
2469 // Two stores in a row of the same value?
2470 if (mem->is_Store() &&
2471 mem->in(MemNode::Address)->eqv_uncast(adr) &&
2472 mem->in(MemNode::ValueIn)->eqv_uncast(val) &&
2473 mem->Opcode() == Opcode()) {
2474 return mem;
2475 }
2476
2477 // Store of zero anywhere into a freshly-allocated object?
2478 // Then the store is useless.
2479 // (It must already have been captured by the InitializeNode.)
2480 if (ReduceFieldZeroing && phase->type(val)->is_zero_type()) {
2481 // a newly allocated object is already all-zeroes everywhere
2482 if (mem->is_Proj() && mem->in(0)->is_Allocate()) {
2483 return mem;
2484 }
2485
2486 // the store may also apply to zero-bits in an earlier object
2487 Node* prev_mem = find_previous_store(phase);
2488 // Steps (a), (b): Walk past independent stores to find an exact match.
2489 if (prev_mem != NULL) {
2490 Node* prev_val = can_see_stored_value(prev_mem, phase);
2491 if (prev_val != NULL && phase->eqv(prev_val, val)) {
2492 // prev_val and val might differ by a cast; it would be good
2493 // to keep the more informative of the two.
2494 return mem;
2495 }
2496 }
2497 }
2498
2499 return this;
2500 }
2501
2502 //------------------------------match_edge-------------------------------------
2503 // Do we Match on this edge index or not? Match only memory & value
2504 uint StoreNode::match_edge(uint idx) const {
2505 return idx == MemNode::Address || idx == MemNode::ValueIn;
2506 }
2507
2508 //------------------------------cmp--------------------------------------------
2509 // Do not common stores up together. They generally have to be split
2510 // back up anyways, so do not bother.
2511 uint StoreNode::cmp( const Node &n ) const {
2512 return (&n == this); // Always fail except on self
2513 }
2514
2515 //------------------------------Ideal_masked_input-----------------------------
2516 // Check for a useless mask before a partial-word store
2517 // (StoreB ... (AndI valIn conIa) )
2518 // If (conIa & mask == mask) this simplifies to
2519 // (StoreB ... (valIn) )
2520 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
2521 Node *val = in(MemNode::ValueIn);
2522 if( val->Opcode() == Op_AndI ) {
2523 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2524 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
2525 set_req(MemNode::ValueIn, val->in(1));
2526 return this;
2527 }
2528 }
2529 return NULL;
2530 }
2531
2532
2533 //------------------------------Ideal_sign_extended_input----------------------
2534 // Check for useless sign-extension before a partial-word store
2535 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) )
2536 // If (conIL == conIR && conIR <= num_bits) this simplifies to
2537 // (StoreB ... (valIn) )
2538 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) {
2539 Node *val = in(MemNode::ValueIn);
2540 if( val->Opcode() == Op_RShiftI ) {
2541 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2542 if( t && t->is_con() && (t->get_con() <= num_bits) ) {
2543 Node *shl = val->in(1);
2544 if( shl->Opcode() == Op_LShiftI ) {
2545 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int();
2546 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) {
2547 set_req(MemNode::ValueIn, shl->in(1));
2548 return this;
2549 }
2550 }
2551 }
2552 }
2553 return NULL;
2554 }
2555
2556 //------------------------------value_never_loaded-----------------------------------
2557 // Determine whether there are any possible loads of the value stored.
2558 // For simplicity, we actually check if there are any loads from the
2559 // address stored to, not just for loads of the value stored by this node.
2560 //
2561 bool StoreNode::value_never_loaded( PhaseTransform *phase) const {
2562 Node *adr = in(Address);
2563 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
2564 if (adr_oop == NULL)
2565 return false;
2566 if (!adr_oop->is_known_instance_field())
2567 return false; // if not a distinct instance, there may be aliases of the address
2568 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
2569 Node *use = adr->fast_out(i);
2570 if (use->is_Load() || use->is_LoadStore()) {
2571 return false;
2572 }
2573 }
2574 return true;
2575 }
2576
2577 //=============================================================================
2578 //------------------------------Ideal------------------------------------------
2579 // If the store is from an AND mask that leaves the low bits untouched, then
2580 // we can skip the AND operation. If the store is from a sign-extension
2581 // (a left shift, then right shift) we can skip both.
2582 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
2583 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
2584 if( progress != NULL ) return progress;
2585
2586 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
2587 if( progress != NULL ) return progress;
2588
2589 // Finally check the default case
2590 return StoreNode::Ideal(phase, can_reshape);
2591 }
2592
2593 //=============================================================================
2594 //------------------------------Ideal------------------------------------------
2595 // If the store is from an AND mask that leaves the low bits untouched, then
2596 // we can skip the AND operation
2597 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
2598 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
2599 if( progress != NULL ) return progress;
2600
2601 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
2602 if( progress != NULL ) return progress;
2603
2604 // Finally check the default case
2605 return StoreNode::Ideal(phase, can_reshape);
2606 }
2607
2608 //=============================================================================
2609 //------------------------------Identity---------------------------------------
2610 Node *StoreCMNode::Identity( PhaseTransform *phase ) {
2611 // No need to card mark when storing a null ptr
2612 Node* my_store = in(MemNode::OopStore);
2613 if (my_store->is_Store()) {
2614 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) );
2615 if( t1 == TypePtr::NULL_PTR ) {
2616 return in(MemNode::Memory);
2617 }
2618 }
2619 return this;
2620 }
2621
2622 //=============================================================================
2623 //------------------------------Ideal---------------------------------------
2624 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){
2625 Node* progress = StoreNode::Ideal(phase, can_reshape);
2626 if (progress != NULL) return progress;
2627
2628 Node* my_store = in(MemNode::OopStore);
2629 if (my_store->is_MergeMem()) {
2630 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx());
2631 set_req(MemNode::OopStore, mem);
2632 return this;
2633 }
2634
2635 return NULL;
2636 }
2637
2638 //------------------------------Value-----------------------------------------
2639 const Type *StoreCMNode::Value( PhaseTransform *phase ) const {
2640 // Either input is TOP ==> the result is TOP
2641 const Type *t = phase->type( in(MemNode::Memory) );
2642 if( t == Type::TOP ) return Type::TOP;
2643 t = phase->type( in(MemNode::Address) );
2644 if( t == Type::TOP ) return Type::TOP;
2645 t = phase->type( in(MemNode::ValueIn) );
2646 if( t == Type::TOP ) return Type::TOP;
2647 // If extra input is TOP ==> the result is TOP
2648 t = phase->type( in(MemNode::OopStore) );
2649 if( t == Type::TOP ) return Type::TOP;
2650
2651 return StoreNode::Value( phase );
2652 }
2653
2654
2655 //=============================================================================
2656 //----------------------------------SCMemProjNode------------------------------
2657 const Type * SCMemProjNode::Value( PhaseTransform *phase ) const
2658 {
2659 return bottom_type();
2660 }
2661
2662 //=============================================================================
2663 //----------------------------------LoadStoreNode------------------------------
2664 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required )
2665 : Node(required),
2666 _type(rt),
2667 _adr_type(at)
2668 {
2669 init_req(MemNode::Control, c );
2670 init_req(MemNode::Memory , mem);
2671 init_req(MemNode::Address, adr);
2672 init_req(MemNode::ValueIn, val);
2673 init_class_id(Class_LoadStore);
2674 }
2675
2676 uint LoadStoreNode::ideal_reg() const {
2677 return _type->ideal_reg();
2678 }
2679
2680 bool LoadStoreNode::result_not_used() const {
2681 for( DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++ ) {
2682 Node *x = fast_out(i);
2683 if (x->Opcode() == Op_SCMemProj) continue;
2684 return false;
2685 }
2686 return true;
2687 }
2688
2689 uint LoadStoreNode::size_of() const { return sizeof(*this); }
2690
2691 //=============================================================================
2692 //----------------------------------LoadStoreConditionalNode--------------------
2693 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, NULL, TypeInt::BOOL, 5) {
2694 init_req(ExpectedIn, ex );
2695 }
2696
2697 //=============================================================================
2698 //-------------------------------adr_type--------------------------------------
2699 const TypePtr* ClearArrayNode::adr_type() const {
2700 Node *adr = in(3);
2701 if (adr == NULL) return NULL; // node is dead
2702 return MemNode::calculate_adr_type(adr->bottom_type());
2703 }
2704
2705 //------------------------------match_edge-------------------------------------
2706 // Do we Match on this edge index or not? Do not match memory
2707 uint ClearArrayNode::match_edge(uint idx) const {
2708 return idx > 1;
2709 }
2710
2711 //------------------------------Identity---------------------------------------
2712 // Clearing a zero length array does nothing
2713 Node *ClearArrayNode::Identity( PhaseTransform *phase ) {
2714 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
2715 }
2716
2717 //------------------------------Idealize---------------------------------------
2718 // Clearing a short array is faster with stores
2719 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape){
2720 const int unit = BytesPerLong;
2721 const TypeX* t = phase->type(in(2))->isa_intptr_t();
2722 if (!t) return NULL;
2723 if (!t->is_con()) return NULL;
2724 intptr_t raw_count = t->get_con();
2725 intptr_t size = raw_count;
2726 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
2727 // Clearing nothing uses the Identity call.
2728 // Negative clears are possible on dead ClearArrays
2729 // (see jck test stmt114.stmt11402.val).
2730 if (size <= 0 || size % unit != 0) return NULL;
2731 intptr_t count = size / unit;
2732 // Length too long; use fast hardware clear
2733 if (size > Matcher::init_array_short_size) return NULL;
2734 Node *mem = in(1);
2735 if( phase->type(mem)==Type::TOP ) return NULL;
2736 Node *adr = in(3);
2737 const Type* at = phase->type(adr);
2738 if( at==Type::TOP ) return NULL;
2739 const TypePtr* atp = at->isa_ptr();
2740 // adjust atp to be the correct array element address type
2741 if (atp == NULL) atp = TypePtr::BOTTOM;
2742 else atp = atp->add_offset(Type::OffsetBot);
2743 // Get base for derived pointer purposes
2744 if( adr->Opcode() != Op_AddP ) Unimplemented();
2745 Node *base = adr->in(1);
2746
2747 Node *zero = phase->makecon(TypeLong::ZERO);
2748 Node *off = phase->MakeConX(BytesPerLong);
2749 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
2750 count--;
2751 while( count-- ) {
2752 mem = phase->transform(mem);
2753 adr = phase->transform(new AddPNode(base,adr,off));
2754 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
2755 }
2756 return mem;
2757 }
2758
2759 //----------------------------step_through----------------------------------
2760 // Return allocation input memory edge if it is different instance
2761 // or itself if it is the one we are looking for.
2762 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) {
2763 Node* n = *np;
2764 assert(n->is_ClearArray(), "sanity");
2765 intptr_t offset;
2766 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
2767 // This method is called only before Allocate nodes are expanded
2768 // during macro nodes expansion. Before that ClearArray nodes are
2769 // only generated in PhaseMacroExpand::generate_arraycopy() (before
2770 // Allocate nodes are expanded) which follows allocations.
2771 assert(alloc != NULL, "should have allocation");
2772 if (alloc->_idx == instance_id) {
2773 // Can not bypass initialization of the instance we are looking for.
2774 return false;
2775 }
2776 // Otherwise skip it.
2777 InitializeNode* init = alloc->initialization();
2778 if (init != NULL)
2779 *np = init->in(TypeFunc::Memory);
2780 else
2781 *np = alloc->in(TypeFunc::Memory);
2782 return true;
2783 }
2784
2785 //----------------------------clear_memory-------------------------------------
2786 // Generate code to initialize object storage to zero.
2787 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2788 intptr_t start_offset,
2789 Node* end_offset,
2790 PhaseGVN* phase) {
2791 intptr_t offset = start_offset;
2792
2793 int unit = BytesPerLong;
2794 if ((offset % unit) != 0) {
2795 Node* adr = new AddPNode(dest, dest, phase->MakeConX(offset));
2796 adr = phase->transform(adr);
2797 const TypePtr* atp = TypeRawPtr::BOTTOM;
2798 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
2799 mem = phase->transform(mem);
2800 offset += BytesPerInt;
2801 }
2802 assert((offset % unit) == 0, "");
2803
2804 // Initialize the remaining stuff, if any, with a ClearArray.
2805 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase);
2806 }
2807
2808 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2809 Node* start_offset,
2810 Node* end_offset,
2811 PhaseGVN* phase) {
2812 if (start_offset == end_offset) {
2813 // nothing to do
2814 return mem;
2815 }
2816
2817 int unit = BytesPerLong;
2818 Node* zbase = start_offset;
2819 Node* zend = end_offset;
2820
2821 // Scale to the unit required by the CPU:
2822 if (!Matcher::init_array_count_is_in_bytes) {
2823 Node* shift = phase->intcon(exact_log2(unit));
2824 zbase = phase->transform(new URShiftXNode(zbase, shift) );
2825 zend = phase->transform(new URShiftXNode(zend, shift) );
2826 }
2827
2828 // Bulk clear double-words
2829 Node* zsize = phase->transform(new SubXNode(zend, zbase) );
2830 Node* adr = phase->transform(new AddPNode(dest, dest, start_offset) );
2831 mem = new ClearArrayNode(ctl, mem, zsize, adr);
2832 return phase->transform(mem);
2833 }
2834
2835 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2836 intptr_t start_offset,
2837 intptr_t end_offset,
2838 PhaseGVN* phase) {
2839 if (start_offset == end_offset) {
2840 // nothing to do
2841 return mem;
2842 }
2843
2844 assert((end_offset % BytesPerInt) == 0, "odd end offset");
2845 intptr_t done_offset = end_offset;
2846 if ((done_offset % BytesPerLong) != 0) {
2847 done_offset -= BytesPerInt;
2848 }
2849 if (done_offset > start_offset) {
2850 mem = clear_memory(ctl, mem, dest,
2851 start_offset, phase->MakeConX(done_offset), phase);
2852 }
2853 if (done_offset < end_offset) { // emit the final 32-bit store
2854 Node* adr = new AddPNode(dest, dest, phase->MakeConX(done_offset));
2855 adr = phase->transform(adr);
2856 const TypePtr* atp = TypeRawPtr::BOTTOM;
2857 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
2858 mem = phase->transform(mem);
2859 done_offset += BytesPerInt;
2860 }
2861 assert(done_offset == end_offset, "");
2862 return mem;
2863 }
2864
2865 //=============================================================================
2866 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
2867 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)),
2868 _adr_type(C->get_adr_type(alias_idx))
2869 {
2870 init_class_id(Class_MemBar);
2871 Node* top = C->top();
2872 init_req(TypeFunc::I_O,top);
2873 init_req(TypeFunc::FramePtr,top);
2874 init_req(TypeFunc::ReturnAdr,top);
2875 if (precedent != NULL)
2876 init_req(TypeFunc::Parms, precedent);
2877 }
2878
2879 //------------------------------cmp--------------------------------------------
2880 uint MemBarNode::hash() const { return NO_HASH; }
2881 uint MemBarNode::cmp( const Node &n ) const {
2882 return (&n == this); // Always fail except on self
2883 }
2884
2885 //------------------------------make-------------------------------------------
2886 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
2887 switch (opcode) {
2888 case Op_MemBarAcquire: return new MemBarAcquireNode(C, atp, pn);
2889 case Op_LoadFence: return new LoadFenceNode(C, atp, pn);
2890 case Op_MemBarRelease: return new MemBarReleaseNode(C, atp, pn);
2891 case Op_StoreFence: return new StoreFenceNode(C, atp, pn);
2892 case Op_MemBarAcquireLock: return new MemBarAcquireLockNode(C, atp, pn);
2893 case Op_MemBarReleaseLock: return new MemBarReleaseLockNode(C, atp, pn);
2894 case Op_MemBarVolatile: return new MemBarVolatileNode(C, atp, pn);
2895 case Op_MemBarCPUOrder: return new MemBarCPUOrderNode(C, atp, pn);
2896 case Op_Initialize: return new InitializeNode(C, atp, pn);
2897 case Op_MemBarStoreStore: return new MemBarStoreStoreNode(C, atp, pn);
2898 default: ShouldNotReachHere(); return NULL;
2899 }
2900 }
2901
2902 //------------------------------Ideal------------------------------------------
2903 // Return a node which is more "ideal" than the current node. Strip out
2904 // control copies
2905 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2906 if (remove_dead_region(phase, can_reshape)) return this;
2907 // Don't bother trying to transform a dead node
2908 if (in(0) && in(0)->is_top()) {
2909 return NULL;
2910 }
2911
2912 bool progress = false;
2913 // Eliminate volatile MemBars for scalar replaced objects.
2914 if (can_reshape && req() == (Precedent+1)) {
2915 bool eliminate = false;
2916 int opc = Opcode();
2917 if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) {
2918 // Volatile field loads and stores.
2919 Node* my_mem = in(MemBarNode::Precedent);
2920 // The MembarAquire may keep an unused LoadNode alive through the Precedent edge
2921 if ((my_mem != NULL) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) {
2922 // if the Precedent is a decodeN and its input (a Load) is used at more than one place,
2923 // replace this Precedent (decodeN) with the Load instead.
2924 if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1)) {
2925 Node* load_node = my_mem->in(1);
2926 set_req(MemBarNode::Precedent, load_node);
2927 phase->is_IterGVN()->_worklist.push(my_mem);
2928 my_mem = load_node;
2929 } else {
2930 assert(my_mem->unique_out() == this, "sanity");
2931 del_req(Precedent);
2932 phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later
2933 my_mem = NULL;
2934 }
2935 progress = true;
2936 }
2937 if (my_mem != NULL && my_mem->is_Mem()) {
2938 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
2939 // Check for scalar replaced object reference.
2940 if( t_oop != NULL && t_oop->is_known_instance_field() &&
2941 t_oop->offset() != Type::OffsetBot &&
2942 t_oop->offset() != Type::OffsetTop) {
2943 eliminate = true;
2944 }
2945 }
2946 } else if (opc == Op_MemBarRelease) {
2947 // Final field stores.
2948 Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent), phase);
2949 if ((alloc != NULL) && alloc->is_Allocate() &&
2950 alloc->as_Allocate()->_is_non_escaping) {
2951 // The allocated object does not escape.
2952 eliminate = true;
2953 }
2954 }
2955 if (eliminate) {
2956 // Replace MemBar projections by its inputs.
2957 PhaseIterGVN* igvn = phase->is_IterGVN();
2958 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
2959 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
2960 // Must return either the original node (now dead) or a new node
2961 // (Do not return a top here, since that would break the uniqueness of top.)
2962 return new ConINode(TypeInt::ZERO);
2963 }
2964 }
2965 return progress ? this : NULL;
2966 }
2967
2968 //------------------------------Value------------------------------------------
2969 const Type *MemBarNode::Value( PhaseTransform *phase ) const {
2970 if( !in(0) ) return Type::TOP;
2971 if( phase->type(in(0)) == Type::TOP )
2972 return Type::TOP;
2973 return TypeTuple::MEMBAR;
2974 }
2975
2976 //------------------------------match------------------------------------------
2977 // Construct projections for memory.
2978 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) {
2979 switch (proj->_con) {
2980 case TypeFunc::Control:
2981 case TypeFunc::Memory:
2982 return new MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
2983 }
2984 ShouldNotReachHere();
2985 return NULL;
2986 }
2987
2988 //===========================InitializeNode====================================
2989 // SUMMARY:
2990 // This node acts as a memory barrier on raw memory, after some raw stores.
2991 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
2992 // The Initialize can 'capture' suitably constrained stores as raw inits.
2993 // It can coalesce related raw stores into larger units (called 'tiles').
2994 // It can avoid zeroing new storage for memory units which have raw inits.
2995 // At macro-expansion, it is marked 'complete', and does not optimize further.
2996 //
2997 // EXAMPLE:
2998 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
2999 // ctl = incoming control; mem* = incoming memory
3000 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
3001 // First allocate uninitialized memory and fill in the header:
3002 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
3003 // ctl := alloc.Control; mem* := alloc.Memory*
3004 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
3005 // Then initialize to zero the non-header parts of the raw memory block:
3006 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
3007 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
3008 // After the initialize node executes, the object is ready for service:
3009 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
3010 // Suppose its body is immediately initialized as {1,2}:
3011 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3012 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3013 // mem.SLICE(#short[*]) := store2
3014 //
3015 // DETAILS:
3016 // An InitializeNode collects and isolates object initialization after
3017 // an AllocateNode and before the next possible safepoint. As a
3018 // memory barrier (MemBarNode), it keeps critical stores from drifting
3019 // down past any safepoint or any publication of the allocation.
3020 // Before this barrier, a newly-allocated object may have uninitialized bits.
3021 // After this barrier, it may be treated as a real oop, and GC is allowed.
3022 //
3023 // The semantics of the InitializeNode include an implicit zeroing of
3024 // the new object from object header to the end of the object.
3025 // (The object header and end are determined by the AllocateNode.)
3026 //
3027 // Certain stores may be added as direct inputs to the InitializeNode.
3028 // These stores must update raw memory, and they must be to addresses
3029 // derived from the raw address produced by AllocateNode, and with
3030 // a constant offset. They must be ordered by increasing offset.
3031 // The first one is at in(RawStores), the last at in(req()-1).
3032 // Unlike most memory operations, they are not linked in a chain,
3033 // but are displayed in parallel as users of the rawmem output of
3034 // the allocation.
3035 //
3036 // (See comments in InitializeNode::capture_store, which continue
3037 // the example given above.)
3038 //
3039 // When the associated Allocate is macro-expanded, the InitializeNode
3040 // may be rewritten to optimize collected stores. A ClearArrayNode
3041 // may also be created at that point to represent any required zeroing.
3042 // The InitializeNode is then marked 'complete', prohibiting further
3043 // capturing of nearby memory operations.
3044 //
3045 // During macro-expansion, all captured initializations which store
3046 // constant values of 32 bits or smaller are coalesced (if advantageous)
3047 // into larger 'tiles' 32 or 64 bits. This allows an object to be
3048 // initialized in fewer memory operations. Memory words which are
3049 // covered by neither tiles nor non-constant stores are pre-zeroed
3050 // by explicit stores of zero. (The code shape happens to do all
3051 // zeroing first, then all other stores, with both sequences occurring
3052 // in order of ascending offsets.)
3053 //
3054 // Alternatively, code may be inserted between an AllocateNode and its
3055 // InitializeNode, to perform arbitrary initialization of the new object.
3056 // E.g., the object copying intrinsics insert complex data transfers here.
3057 // The initialization must then be marked as 'complete' disable the
3058 // built-in zeroing semantics and the collection of initializing stores.
3059 //
3060 // While an InitializeNode is incomplete, reads from the memory state
3061 // produced by it are optimizable if they match the control edge and
3062 // new oop address associated with the allocation/initialization.
3063 // They return a stored value (if the offset matches) or else zero.
3064 // A write to the memory state, if it matches control and address,
3065 // and if it is to a constant offset, may be 'captured' by the
3066 // InitializeNode. It is cloned as a raw memory operation and rewired
3067 // inside the initialization, to the raw oop produced by the allocation.
3068 // Operations on addresses which are provably distinct (e.g., to
3069 // other AllocateNodes) are allowed to bypass the initialization.
3070 //
3071 // The effect of all this is to consolidate object initialization
3072 // (both arrays and non-arrays, both piecewise and bulk) into a
3073 // single location, where it can be optimized as a unit.
3074 //
3075 // Only stores with an offset less than TrackedInitializationLimit words
3076 // will be considered for capture by an InitializeNode. This puts a
3077 // reasonable limit on the complexity of optimized initializations.
3078
3079 //---------------------------InitializeNode------------------------------------
3080 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
3081 : _is_complete(Incomplete), _does_not_escape(false),
3082 MemBarNode(C, adr_type, rawoop)
3083 {
3084 init_class_id(Class_Initialize);
3085
3086 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
3087 assert(in(RawAddress) == rawoop, "proper init");
3088 // Note: allocation() can be NULL, for secondary initialization barriers
3089 }
3090
3091 // Since this node is not matched, it will be processed by the
3092 // register allocator. Declare that there are no constraints
3093 // on the allocation of the RawAddress edge.
3094 const RegMask &InitializeNode::in_RegMask(uint idx) const {
3095 // This edge should be set to top, by the set_complete. But be conservative.
3096 if (idx == InitializeNode::RawAddress)
3097 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
3098 return RegMask::Empty;
3099 }
3100
3101 Node* InitializeNode::memory(uint alias_idx) {
3102 Node* mem = in(Memory);
3103 if (mem->is_MergeMem()) {
3104 return mem->as_MergeMem()->memory_at(alias_idx);
3105 } else {
3106 // incoming raw memory is not split
3107 return mem;
3108 }
3109 }
3110
3111 bool InitializeNode::is_non_zero() {
3112 if (is_complete()) return false;
3113 remove_extra_zeroes();
3114 return (req() > RawStores);
3115 }
3116
3117 void InitializeNode::set_complete(PhaseGVN* phase) {
3118 assert(!is_complete(), "caller responsibility");
3119 _is_complete = Complete;
3120
3121 // After this node is complete, it contains a bunch of
3122 // raw-memory initializations. There is no need for
3123 // it to have anything to do with non-raw memory effects.
3124 // Therefore, tell all non-raw users to re-optimize themselves,
3125 // after skipping the memory effects of this initialization.
3126 PhaseIterGVN* igvn = phase->is_IterGVN();
3127 if (igvn) igvn->add_users_to_worklist(this);
3128 }
3129
3130 // convenience function
3131 // return false if the init contains any stores already
3132 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
3133 InitializeNode* init = initialization();
3134 if (init == NULL || init->is_complete()) return false;
3135 init->remove_extra_zeroes();
3136 // for now, if this allocation has already collected any inits, bail:
3137 if (init->is_non_zero()) return false;
3138 init->set_complete(phase);
3139 return true;
3140 }
3141
3142 void InitializeNode::remove_extra_zeroes() {
3143 if (req() == RawStores) return;
3144 Node* zmem = zero_memory();
3145 uint fill = RawStores;
3146 for (uint i = fill; i < req(); i++) {
3147 Node* n = in(i);
3148 if (n->is_top() || n == zmem) continue; // skip
3149 if (fill < i) set_req(fill, n); // compact
3150 ++fill;
3151 }
3152 // delete any empty spaces created:
3153 while (fill < req()) {
3154 del_req(fill);
3155 }
3156 }
3157
3158 // Helper for remembering which stores go with which offsets.
3159 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) {
3160 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
3161 intptr_t offset = -1;
3162 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
3163 phase, offset);
3164 if (base == NULL) return -1; // something is dead,
3165 if (offset < 0) return -1; // dead, dead
3166 return offset;
3167 }
3168
3169 // Helper for proving that an initialization expression is
3170 // "simple enough" to be folded into an object initialization.
3171 // Attempts to prove that a store's initial value 'n' can be captured
3172 // within the initialization without creating a vicious cycle, such as:
3173 // { Foo p = new Foo(); p.next = p; }
3174 // True for constants and parameters and small combinations thereof.
3175 bool InitializeNode::detect_init_independence(Node* n, int& count) {
3176 if (n == NULL) return true; // (can this really happen?)
3177 if (n->is_Proj()) n = n->in(0);
3178 if (n == this) return false; // found a cycle
3179 if (n->is_Con()) return true;
3180 if (n->is_Start()) return true; // params, etc., are OK
3181 if (n->is_Root()) return true; // even better
3182
3183 Node* ctl = n->in(0);
3184 if (ctl != NULL && !ctl->is_top()) {
3185 if (ctl->is_Proj()) ctl = ctl->in(0);
3186 if (ctl == this) return false;
3187
3188 // If we already know that the enclosing memory op is pinned right after
3189 // the init, then any control flow that the store has picked up
3190 // must have preceded the init, or else be equal to the init.
3191 // Even after loop optimizations (which might change control edges)
3192 // a store is never pinned *before* the availability of its inputs.
3193 if (!MemNode::all_controls_dominate(n, this))
3194 return false; // failed to prove a good control
3195 }
3196
3197 // Check data edges for possible dependencies on 'this'.
3198 if ((count += 1) > 20) return false; // complexity limit
3199 for (uint i = 1; i < n->req(); i++) {
3200 Node* m = n->in(i);
3201 if (m == NULL || m == n || m->is_top()) continue;
3202 uint first_i = n->find_edge(m);
3203 if (i != first_i) continue; // process duplicate edge just once
3204 if (!detect_init_independence(m, count)) {
3205 return false;
3206 }
3207 }
3208
3209 return true;
3210 }
3211
3212 // Here are all the checks a Store must pass before it can be moved into
3213 // an initialization. Returns zero if a check fails.
3214 // On success, returns the (constant) offset to which the store applies,
3215 // within the initialized memory.
3216 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase, bool can_reshape) {
3217 const int FAIL = 0;
3218 if (st->req() != MemNode::ValueIn + 1)
3219 return FAIL; // an inscrutable StoreNode (card mark?)
3220 Node* ctl = st->in(MemNode::Control);
3221 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this))
3222 return FAIL; // must be unconditional after the initialization
3223 Node* mem = st->in(MemNode::Memory);
3224 if (!(mem->is_Proj() && mem->in(0) == this))
3225 return FAIL; // must not be preceded by other stores
3226 Node* adr = st->in(MemNode::Address);
3227 intptr_t offset;
3228 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
3229 if (alloc == NULL)
3230 return FAIL; // inscrutable address
3231 if (alloc != allocation())
3232 return FAIL; // wrong allocation! (store needs to float up)
3233 Node* val = st->in(MemNode::ValueIn);
3234 int complexity_count = 0;
3235 if (!detect_init_independence(val, complexity_count))
3236 return FAIL; // stored value must be 'simple enough'
3237
3238 // The Store can be captured only if nothing after the allocation
3239 // and before the Store is using the memory location that the store
3240 // overwrites.
3241 bool failed = false;
3242 // If is_complete_with_arraycopy() is true the shape of the graph is
3243 // well defined and is safe so no need for extra checks.
3244 if (!is_complete_with_arraycopy()) {
3245 // We are going to look at each use of the memory state following
3246 // the allocation to make sure nothing reads the memory that the
3247 // Store writes.
3248 const TypePtr* t_adr = phase->type(adr)->isa_ptr();
3249 int alias_idx = phase->C->get_alias_index(t_adr);
3250 ResourceMark rm;
3251 Unique_Node_List mems;
3252 mems.push(mem);
3253 Node* unique_merge = NULL;
3254 for (uint next = 0; next < mems.size(); ++next) {
3255 Node *m = mems.at(next);
3256 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
3257 Node *n = m->fast_out(j);
3258 if (n->outcnt() == 0) {
3259 continue;
3260 }
3261 if (n == st) {
3262 continue;
3263 } else if (n->in(0) != NULL && n->in(0) != ctl) {
3264 // If the control of this use is different from the control
3265 // of the Store which is right after the InitializeNode then
3266 // this node cannot be between the InitializeNode and the
3267 // Store.
3268 continue;
3269 } else if (n->is_MergeMem()) {
3270 if (n->as_MergeMem()->memory_at(alias_idx) == m) {
3271 // We can hit a MergeMemNode (that will likely go away
3272 // later) that is a direct use of the memory state
3273 // following the InitializeNode on the same slice as the
3274 // store node that we'd like to capture. We need to check
3275 // the uses of the MergeMemNode.
3276 mems.push(n);
3277 }
3278 } else if (n->is_Mem()) {
3279 Node* other_adr = n->in(MemNode::Address);
3280 if (other_adr == adr) {
3281 failed = true;
3282 break;
3283 } else {
3284 const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr();
3285 if (other_t_adr != NULL) {
3286 int other_alias_idx = phase->C->get_alias_index(other_t_adr);
3287 if (other_alias_idx == alias_idx) {
3288 // A load from the same memory slice as the store right
3289 // after the InitializeNode. We check the control of the
3290 // object/array that is loaded from. If it's the same as
3291 // the store control then we cannot capture the store.
3292 assert(!n->is_Store(), "2 stores to same slice on same control?");
3293 Node* base = other_adr;
3294 assert(base->is_AddP(), err_msg_res("should be addp but is %s", base->Name()));
3295 base = base->in(AddPNode::Base);
3296 if (base != NULL) {
3297 base = base->uncast();
3298 if (base->is_Proj() && base->in(0) == alloc) {
3299 failed = true;
3300 break;
3301 }
3302 }
3303 }
3304 }
3305 }
3306 } else {
3307 failed = true;
3308 break;
3309 }
3310 }
3311 }
3312 }
3313 if (failed) {
3314 if (!can_reshape) {
3315 // We decided we couldn't capture the store during parsing. We
3316 // should try again during the next IGVN once the graph is
3317 // cleaner.
3318 phase->C->record_for_igvn(st);
3319 }
3320 return FAIL;
3321 }
3322
3323 return offset; // success
3324 }
3325
3326 // Find the captured store in(i) which corresponds to the range
3327 // [start..start+size) in the initialized object.
3328 // If there is one, return its index i. If there isn't, return the
3329 // negative of the index where it should be inserted.
3330 // Return 0 if the queried range overlaps an initialization boundary
3331 // or if dead code is encountered.
3332 // If size_in_bytes is zero, do not bother with overlap checks.
3333 int InitializeNode::captured_store_insertion_point(intptr_t start,
3334 int size_in_bytes,
3335 PhaseTransform* phase) {
3336 const int FAIL = 0, MAX_STORE = BytesPerLong;
3337
3338 if (is_complete())
3339 return FAIL; // arraycopy got here first; punt
3340
3341 assert(allocation() != NULL, "must be present");
3342
3343 // no negatives, no header fields:
3344 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
3345
3346 // after a certain size, we bail out on tracking all the stores:
3347 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3348 if (start >= ti_limit) return FAIL;
3349
3350 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
3351 if (i >= limit) return -(int)i; // not found; here is where to put it
3352
3353 Node* st = in(i);
3354 intptr_t st_off = get_store_offset(st, phase);
3355 if (st_off < 0) {
3356 if (st != zero_memory()) {
3357 return FAIL; // bail out if there is dead garbage
3358 }
3359 } else if (st_off > start) {
3360 // ...we are done, since stores are ordered
3361 if (st_off < start + size_in_bytes) {
3362 return FAIL; // the next store overlaps
3363 }
3364 return -(int)i; // not found; here is where to put it
3365 } else if (st_off < start) {
3366 if (size_in_bytes != 0 &&
3367 start < st_off + MAX_STORE &&
3368 start < st_off + st->as_Store()->memory_size()) {
3369 return FAIL; // the previous store overlaps
3370 }
3371 } else {
3372 if (size_in_bytes != 0 &&
3373 st->as_Store()->memory_size() != size_in_bytes) {
3374 return FAIL; // mismatched store size
3375 }
3376 return i;
3377 }
3378
3379 ++i;
3380 }
3381 }
3382
3383 // Look for a captured store which initializes at the offset 'start'
3384 // with the given size. If there is no such store, and no other
3385 // initialization interferes, then return zero_memory (the memory
3386 // projection of the AllocateNode).
3387 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
3388 PhaseTransform* phase) {
3389 assert(stores_are_sane(phase), "");
3390 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3391 if (i == 0) {
3392 return NULL; // something is dead
3393 } else if (i < 0) {
3394 return zero_memory(); // just primordial zero bits here
3395 } else {
3396 Node* st = in(i); // here is the store at this position
3397 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
3398 return st;
3399 }
3400 }
3401
3402 // Create, as a raw pointer, an address within my new object at 'offset'.
3403 Node* InitializeNode::make_raw_address(intptr_t offset,
3404 PhaseTransform* phase) {
3405 Node* addr = in(RawAddress);
3406 if (offset != 0) {
3407 Compile* C = phase->C;
3408 addr = phase->transform( new AddPNode(C->top(), addr,
3409 phase->MakeConX(offset)) );
3410 }
3411 return addr;
3412 }
3413
3414 // Clone the given store, converting it into a raw store
3415 // initializing a field or element of my new object.
3416 // Caller is responsible for retiring the original store,
3417 // with subsume_node or the like.
3418 //
3419 // From the example above InitializeNode::InitializeNode,
3420 // here are the old stores to be captured:
3421 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3422 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3423 //
3424 // Here is the changed code; note the extra edges on init:
3425 // alloc = (Allocate ...)
3426 // rawoop = alloc.RawAddress
3427 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
3428 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
3429 // init = (Initialize alloc.Control alloc.Memory rawoop
3430 // rawstore1 rawstore2)
3431 //
3432 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
3433 PhaseTransform* phase, bool can_reshape) {
3434 assert(stores_are_sane(phase), "");
3435
3436 if (start < 0) return NULL;
3437 assert(can_capture_store(st, phase, can_reshape) == start, "sanity");
3438
3439 Compile* C = phase->C;
3440 int size_in_bytes = st->memory_size();
3441 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3442 if (i == 0) return NULL; // bail out
3443 Node* prev_mem = NULL; // raw memory for the captured store
3444 if (i > 0) {
3445 prev_mem = in(i); // there is a pre-existing store under this one
3446 set_req(i, C->top()); // temporarily disconnect it
3447 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
3448 } else {
3449 i = -i; // no pre-existing store
3450 prev_mem = zero_memory(); // a slice of the newly allocated object
3451 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
3452 set_req(--i, C->top()); // reuse this edge; it has been folded away
3453 else
3454 ins_req(i, C->top()); // build a new edge
3455 }
3456 Node* new_st = st->clone();
3457 new_st->set_req(MemNode::Control, in(Control));
3458 new_st->set_req(MemNode::Memory, prev_mem);
3459 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
3460 new_st = phase->transform(new_st);
3461
3462 // At this point, new_st might have swallowed a pre-existing store
3463 // at the same offset, or perhaps new_st might have disappeared,
3464 // if it redundantly stored the same value (or zero to fresh memory).
3465
3466 // In any case, wire it in:
3467 phase->igvn_rehash_node_delayed(this);
3468 set_req(i, new_st);
3469
3470 // The caller may now kill the old guy.
3471 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
3472 assert(check_st == new_st || check_st == NULL, "must be findable");
3473 assert(!is_complete(), "");
3474 return new_st;
3475 }
3476
3477 static bool store_constant(jlong* tiles, int num_tiles,
3478 intptr_t st_off, int st_size,
3479 jlong con) {
3480 if ((st_off & (st_size-1)) != 0)
3481 return false; // strange store offset (assume size==2**N)
3482 address addr = (address)tiles + st_off;
3483 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
3484 switch (st_size) {
3485 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
3486 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
3487 case sizeof(jint): *(jint*) addr = (jint) con; break;
3488 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
3489 default: return false; // strange store size (detect size!=2**N here)
3490 }
3491 return true; // return success to caller
3492 }
3493
3494 // Coalesce subword constants into int constants and possibly
3495 // into long constants. The goal, if the CPU permits,
3496 // is to initialize the object with a small number of 64-bit tiles.
3497 // Also, convert floating-point constants to bit patterns.
3498 // Non-constants are not relevant to this pass.
3499 //
3500 // In terms of the running example on InitializeNode::InitializeNode
3501 // and InitializeNode::capture_store, here is the transformation
3502 // of rawstore1 and rawstore2 into rawstore12:
3503 // alloc = (Allocate ...)
3504 // rawoop = alloc.RawAddress
3505 // tile12 = 0x00010002
3506 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
3507 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
3508 //
3509 void
3510 InitializeNode::coalesce_subword_stores(intptr_t header_size,
3511 Node* size_in_bytes,
3512 PhaseGVN* phase) {
3513 Compile* C = phase->C;
3514
3515 assert(stores_are_sane(phase), "");
3516 // Note: After this pass, they are not completely sane,
3517 // since there may be some overlaps.
3518
3519 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
3520
3521 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3522 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
3523 size_limit = MIN2(size_limit, ti_limit);
3524 size_limit = align_size_up(size_limit, BytesPerLong);
3525 int num_tiles = size_limit / BytesPerLong;
3526
3527 // allocate space for the tile map:
3528 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
3529 jlong tiles_buf[small_len];
3530 Node* nodes_buf[small_len];
3531 jlong inits_buf[small_len];
3532 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
3533 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3534 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
3535 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
3536 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
3537 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3538 // tiles: exact bitwise model of all primitive constants
3539 // nodes: last constant-storing node subsumed into the tiles model
3540 // inits: which bytes (in each tile) are touched by any initializations
3541
3542 //// Pass A: Fill in the tile model with any relevant stores.
3543
3544 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
3545 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
3546 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
3547 Node* zmem = zero_memory(); // initially zero memory state
3548 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3549 Node* st = in(i);
3550 intptr_t st_off = get_store_offset(st, phase);
3551
3552 // Figure out the store's offset and constant value:
3553 if (st_off < header_size) continue; //skip (ignore header)
3554 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
3555 int st_size = st->as_Store()->memory_size();
3556 if (st_off + st_size > size_limit) break;
3557
3558 // Record which bytes are touched, whether by constant or not.
3559 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
3560 continue; // skip (strange store size)
3561
3562 const Type* val = phase->type(st->in(MemNode::ValueIn));
3563 if (!val->singleton()) continue; //skip (non-con store)
3564 BasicType type = val->basic_type();
3565
3566 jlong con = 0;
3567 switch (type) {
3568 case T_INT: con = val->is_int()->get_con(); break;
3569 case T_LONG: con = val->is_long()->get_con(); break;
3570 case T_FLOAT: con = jint_cast(val->getf()); break;
3571 case T_DOUBLE: con = jlong_cast(val->getd()); break;
3572 default: continue; //skip (odd store type)
3573 }
3574
3575 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
3576 st->Opcode() == Op_StoreL) {
3577 continue; // This StoreL is already optimal.
3578 }
3579
3580 // Store down the constant.
3581 store_constant(tiles, num_tiles, st_off, st_size, con);
3582
3583 intptr_t j = st_off >> LogBytesPerLong;
3584
3585 if (type == T_INT && st_size == BytesPerInt
3586 && (st_off & BytesPerInt) == BytesPerInt) {
3587 jlong lcon = tiles[j];
3588 if (!Matcher::isSimpleConstant64(lcon) &&
3589 st->Opcode() == Op_StoreI) {
3590 // This StoreI is already optimal by itself.
3591 jint* intcon = (jint*) &tiles[j];
3592 intcon[1] = 0; // undo the store_constant()
3593
3594 // If the previous store is also optimal by itself, back up and
3595 // undo the action of the previous loop iteration... if we can.
3596 // But if we can't, just let the previous half take care of itself.
3597 st = nodes[j];
3598 st_off -= BytesPerInt;
3599 con = intcon[0];
3600 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) {
3601 assert(st_off >= header_size, "still ignoring header");
3602 assert(get_store_offset(st, phase) == st_off, "must be");
3603 assert(in(i-1) == zmem, "must be");
3604 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
3605 assert(con == tcon->is_int()->get_con(), "must be");
3606 // Undo the effects of the previous loop trip, which swallowed st:
3607 intcon[0] = 0; // undo store_constant()
3608 set_req(i-1, st); // undo set_req(i, zmem)
3609 nodes[j] = NULL; // undo nodes[j] = st
3610 --old_subword; // undo ++old_subword
3611 }
3612 continue; // This StoreI is already optimal.
3613 }
3614 }
3615
3616 // This store is not needed.
3617 set_req(i, zmem);
3618 nodes[j] = st; // record for the moment
3619 if (st_size < BytesPerLong) // something has changed
3620 ++old_subword; // includes int/float, but who's counting...
3621 else ++old_long;
3622 }
3623
3624 if ((old_subword + old_long) == 0)
3625 return; // nothing more to do
3626
3627 //// Pass B: Convert any non-zero tiles into optimal constant stores.
3628 // Be sure to insert them before overlapping non-constant stores.
3629 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
3630 for (int j = 0; j < num_tiles; j++) {
3631 jlong con = tiles[j];
3632 jlong init = inits[j];
3633 if (con == 0) continue;
3634 jint con0, con1; // split the constant, address-wise
3635 jint init0, init1; // split the init map, address-wise
3636 { union { jlong con; jint intcon[2]; } u;
3637 u.con = con;
3638 con0 = u.intcon[0];
3639 con1 = u.intcon[1];
3640 u.con = init;
3641 init0 = u.intcon[0];
3642 init1 = u.intcon[1];
3643 }
3644
3645 Node* old = nodes[j];
3646 assert(old != NULL, "need the prior store");
3647 intptr_t offset = (j * BytesPerLong);
3648
3649 bool split = !Matcher::isSimpleConstant64(con);
3650
3651 if (offset < header_size) {
3652 assert(offset + BytesPerInt >= header_size, "second int counts");
3653 assert(*(jint*)&tiles[j] == 0, "junk in header");
3654 split = true; // only the second word counts
3655 // Example: int a[] = { 42 ... }
3656 } else if (con0 == 0 && init0 == -1) {
3657 split = true; // first word is covered by full inits
3658 // Example: int a[] = { ... foo(), 42 ... }
3659 } else if (con1 == 0 && init1 == -1) {
3660 split = true; // second word is covered by full inits
3661 // Example: int a[] = { ... 42, foo() ... }
3662 }
3663
3664 // Here's a case where init0 is neither 0 nor -1:
3665 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
3666 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
3667 // In this case the tile is not split; it is (jlong)42.
3668 // The big tile is stored down, and then the foo() value is inserted.
3669 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
3670
3671 Node* ctl = old->in(MemNode::Control);
3672 Node* adr = make_raw_address(offset, phase);
3673 const TypePtr* atp = TypeRawPtr::BOTTOM;
3674
3675 // One or two coalesced stores to plop down.
3676 Node* st[2];
3677 intptr_t off[2];
3678 int nst = 0;
3679 if (!split) {
3680 ++new_long;
3681 off[nst] = offset;
3682 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3683 phase->longcon(con), T_LONG, MemNode::unordered);
3684 } else {
3685 // Omit either if it is a zero.
3686 if (con0 != 0) {
3687 ++new_int;
3688 off[nst] = offset;
3689 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3690 phase->intcon(con0), T_INT, MemNode::unordered);
3691 }
3692 if (con1 != 0) {
3693 ++new_int;
3694 offset += BytesPerInt;
3695 adr = make_raw_address(offset, phase);
3696 off[nst] = offset;
3697 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3698 phase->intcon(con1), T_INT, MemNode::unordered);
3699 }
3700 }
3701
3702 // Insert second store first, then the first before the second.
3703 // Insert each one just before any overlapping non-constant stores.
3704 while (nst > 0) {
3705 Node* st1 = st[--nst];
3706 C->copy_node_notes_to(st1, old);
3707 st1 = phase->transform(st1);
3708 offset = off[nst];
3709 assert(offset >= header_size, "do not smash header");
3710 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
3711 guarantee(ins_idx != 0, "must re-insert constant store");
3712 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
3713 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
3714 set_req(--ins_idx, st1);
3715 else
3716 ins_req(ins_idx, st1);
3717 }
3718 }
3719
3720 if (PrintCompilation && WizardMode)
3721 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
3722 old_subword, old_long, new_int, new_long);
3723 if (C->log() != NULL)
3724 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
3725 old_subword, old_long, new_int, new_long);
3726
3727 // Clean up any remaining occurrences of zmem:
3728 remove_extra_zeroes();
3729 }
3730
3731 // Explore forward from in(start) to find the first fully initialized
3732 // word, and return its offset. Skip groups of subword stores which
3733 // together initialize full words. If in(start) is itself part of a
3734 // fully initialized word, return the offset of in(start). If there
3735 // are no following full-word stores, or if something is fishy, return
3736 // a negative value.
3737 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
3738 int int_map = 0;
3739 intptr_t int_map_off = 0;
3740 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
3741
3742 for (uint i = start, limit = req(); i < limit; i++) {
3743 Node* st = in(i);
3744
3745 intptr_t st_off = get_store_offset(st, phase);
3746 if (st_off < 0) break; // return conservative answer
3747
3748 int st_size = st->as_Store()->memory_size();
3749 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
3750 return st_off; // we found a complete word init
3751 }
3752
3753 // update the map:
3754
3755 intptr_t this_int_off = align_size_down(st_off, BytesPerInt);
3756 if (this_int_off != int_map_off) {
3757 // reset the map:
3758 int_map = 0;
3759 int_map_off = this_int_off;
3760 }
3761
3762 int subword_off = st_off - this_int_off;
3763 int_map |= right_n_bits(st_size) << subword_off;
3764 if ((int_map & FULL_MAP) == FULL_MAP) {
3765 return this_int_off; // we found a complete word init
3766 }
3767
3768 // Did this store hit or cross the word boundary?
3769 intptr_t next_int_off = align_size_down(st_off + st_size, BytesPerInt);
3770 if (next_int_off == this_int_off + BytesPerInt) {
3771 // We passed the current int, without fully initializing it.
3772 int_map_off = next_int_off;
3773 int_map >>= BytesPerInt;
3774 } else if (next_int_off > this_int_off + BytesPerInt) {
3775 // We passed the current and next int.
3776 return this_int_off + BytesPerInt;
3777 }
3778 }
3779
3780 return -1;
3781 }
3782
3783
3784 // Called when the associated AllocateNode is expanded into CFG.
3785 // At this point, we may perform additional optimizations.
3786 // Linearize the stores by ascending offset, to make memory
3787 // activity as coherent as possible.
3788 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
3789 intptr_t header_size,
3790 Node* size_in_bytes,
3791 PhaseGVN* phase) {
3792 assert(!is_complete(), "not already complete");
3793 assert(stores_are_sane(phase), "");
3794 assert(allocation() != NULL, "must be present");
3795
3796 remove_extra_zeroes();
3797
3798 if (ReduceFieldZeroing || ReduceBulkZeroing)
3799 // reduce instruction count for common initialization patterns
3800 coalesce_subword_stores(header_size, size_in_bytes, phase);
3801
3802 Node* zmem = zero_memory(); // initially zero memory state
3803 Node* inits = zmem; // accumulating a linearized chain of inits
3804 #ifdef ASSERT
3805 intptr_t first_offset = allocation()->minimum_header_size();
3806 intptr_t last_init_off = first_offset; // previous init offset
3807 intptr_t last_init_end = first_offset; // previous init offset+size
3808 intptr_t last_tile_end = first_offset; // previous tile offset+size
3809 #endif
3810 intptr_t zeroes_done = header_size;
3811
3812 bool do_zeroing = true; // we might give up if inits are very sparse
3813 int big_init_gaps = 0; // how many large gaps have we seen?
3814
3815 if (ZeroTLAB) do_zeroing = false;
3816 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
3817
3818 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3819 Node* st = in(i);
3820 intptr_t st_off = get_store_offset(st, phase);
3821 if (st_off < 0)
3822 break; // unknown junk in the inits
3823 if (st->in(MemNode::Memory) != zmem)
3824 break; // complicated store chains somehow in list
3825
3826 int st_size = st->as_Store()->memory_size();
3827 intptr_t next_init_off = st_off + st_size;
3828
3829 if (do_zeroing && zeroes_done < next_init_off) {
3830 // See if this store needs a zero before it or under it.
3831 intptr_t zeroes_needed = st_off;
3832
3833 if (st_size < BytesPerInt) {
3834 // Look for subword stores which only partially initialize words.
3835 // If we find some, we must lay down some word-level zeroes first,
3836 // underneath the subword stores.
3837 //
3838 // Examples:
3839 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
3840 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
3841 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
3842 //
3843 // Note: coalesce_subword_stores may have already done this,
3844 // if it was prompted by constant non-zero subword initializers.
3845 // But this case can still arise with non-constant stores.
3846
3847 intptr_t next_full_store = find_next_fullword_store(i, phase);
3848
3849 // In the examples above:
3850 // in(i) p q r s x y z
3851 // st_off 12 13 14 15 12 13 14
3852 // st_size 1 1 1 1 1 1 1
3853 // next_full_s. 12 16 16 16 16 16 16
3854 // z's_done 12 16 16 16 12 16 12
3855 // z's_needed 12 16 16 16 16 16 16
3856 // zsize 0 0 0 0 4 0 4
3857 if (next_full_store < 0) {
3858 // Conservative tack: Zero to end of current word.
3859 zeroes_needed = align_size_up(zeroes_needed, BytesPerInt);
3860 } else {
3861 // Zero to beginning of next fully initialized word.
3862 // Or, don't zero at all, if we are already in that word.
3863 assert(next_full_store >= zeroes_needed, "must go forward");
3864 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
3865 zeroes_needed = next_full_store;
3866 }
3867 }
3868
3869 if (zeroes_needed > zeroes_done) {
3870 intptr_t zsize = zeroes_needed - zeroes_done;
3871 // Do some incremental zeroing on rawmem, in parallel with inits.
3872 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3873 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3874 zeroes_done, zeroes_needed,
3875 phase);
3876 zeroes_done = zeroes_needed;
3877 if (zsize > Matcher::init_array_short_size && ++big_init_gaps > 2)
3878 do_zeroing = false; // leave the hole, next time
3879 }
3880 }
3881
3882 // Collect the store and move on:
3883 st->set_req(MemNode::Memory, inits);
3884 inits = st; // put it on the linearized chain
3885 set_req(i, zmem); // unhook from previous position
3886
3887 if (zeroes_done == st_off)
3888 zeroes_done = next_init_off;
3889
3890 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
3891
3892 #ifdef ASSERT
3893 // Various order invariants. Weaker than stores_are_sane because
3894 // a large constant tile can be filled in by smaller non-constant stores.
3895 assert(st_off >= last_init_off, "inits do not reverse");
3896 last_init_off = st_off;
3897 const Type* val = NULL;
3898 if (st_size >= BytesPerInt &&
3899 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
3900 (int)val->basic_type() < (int)T_OBJECT) {
3901 assert(st_off >= last_tile_end, "tiles do not overlap");
3902 assert(st_off >= last_init_end, "tiles do not overwrite inits");
3903 last_tile_end = MAX2(last_tile_end, next_init_off);
3904 } else {
3905 intptr_t st_tile_end = align_size_up(next_init_off, BytesPerLong);
3906 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
3907 assert(st_off >= last_init_end, "inits do not overlap");
3908 last_init_end = next_init_off; // it's a non-tile
3909 }
3910 #endif //ASSERT
3911 }
3912
3913 remove_extra_zeroes(); // clear out all the zmems left over
3914 add_req(inits);
3915
3916 if (!ZeroTLAB) {
3917 // If anything remains to be zeroed, zero it all now.
3918 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3919 // if it is the last unused 4 bytes of an instance, forget about it
3920 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
3921 if (zeroes_done + BytesPerLong >= size_limit) {
3922 assert(allocation() != NULL, "");
3923 if (allocation()->Opcode() == Op_Allocate) {
3924 Node* klass_node = allocation()->in(AllocateNode::KlassNode);
3925 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass();
3926 if (zeroes_done == k->layout_helper())
3927 zeroes_done = size_limit;
3928 }
3929 }
3930 if (zeroes_done < size_limit) {
3931 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3932 zeroes_done, size_in_bytes, phase);
3933 }
3934 }
3935
3936 set_complete(phase);
3937 return rawmem;
3938 }
3939
3940
3941 #ifdef ASSERT
3942 bool InitializeNode::stores_are_sane(PhaseTransform* phase) {
3943 if (is_complete())
3944 return true; // stores could be anything at this point
3945 assert(allocation() != NULL, "must be present");
3946 intptr_t last_off = allocation()->minimum_header_size();
3947 for (uint i = InitializeNode::RawStores; i < req(); i++) {
3948 Node* st = in(i);
3949 intptr_t st_off = get_store_offset(st, phase);
3950 if (st_off < 0) continue; // ignore dead garbage
3951 if (last_off > st_off) {
3952 tty->print_cr("*** bad store offset at %d: " INTX_FORMAT " > " INTX_FORMAT, i, last_off, st_off);
3953 this->dump(2);
3954 assert(false, "ascending store offsets");
3955 return false;
3956 }
3957 last_off = st_off + st->as_Store()->memory_size();
3958 }
3959 return true;
3960 }
3961 #endif //ASSERT
3962
3963
3964
3965
3966 //============================MergeMemNode=====================================
3967 //
3968 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
3969 // contributing store or call operations. Each contributor provides the memory
3970 // state for a particular "alias type" (see Compile::alias_type). For example,
3971 // if a MergeMem has an input X for alias category #6, then any memory reference
3972 // to alias category #6 may use X as its memory state input, as an exact equivalent
3973 // to using the MergeMem as a whole.
3974 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
3975 //
3976 // (Here, the <N> notation gives the index of the relevant adr_type.)
3977 //
3978 // In one special case (and more cases in the future), alias categories overlap.
3979 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
3980 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
3981 // it is exactly equivalent to that state W:
3982 // MergeMem(<Bot>: W) <==> W
3983 //
3984 // Usually, the merge has more than one input. In that case, where inputs
3985 // overlap (i.e., one is Bot), the narrower alias type determines the memory
3986 // state for that type, and the wider alias type (Bot) fills in everywhere else:
3987 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
3988 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
3989 //
3990 // A merge can take a "wide" memory state as one of its narrow inputs.
3991 // This simply means that the merge observes out only the relevant parts of
3992 // the wide input. That is, wide memory states arriving at narrow merge inputs
3993 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
3994 //
3995 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
3996 // and that memory slices "leak through":
3997 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
3998 //
3999 // But, in such a cascade, repeated memory slices can "block the leak":
4000 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
4001 //
4002 // In the last example, Y is not part of the combined memory state of the
4003 // outermost MergeMem. The system must, of course, prevent unschedulable
4004 // memory states from arising, so you can be sure that the state Y is somehow
4005 // a precursor to state Y'.
4006 //
4007 //
4008 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
4009 // of each MergeMemNode array are exactly the numerical alias indexes, including
4010 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
4011 // Compile::alias_type (and kin) produce and manage these indexes.
4012 //
4013 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
4014 // (Note that this provides quick access to the top node inside MergeMem methods,
4015 // without the need to reach out via TLS to Compile::current.)
4016 //
4017 // As a consequence of what was just described, a MergeMem that represents a full
4018 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
4019 // containing all alias categories.
4020 //
4021 // MergeMem nodes never (?) have control inputs, so in(0) is NULL.
4022 //
4023 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
4024 // a memory state for the alias type <N>, or else the top node, meaning that
4025 // there is no particular input for that alias type. Note that the length of
4026 // a MergeMem is variable, and may be extended at any time to accommodate new
4027 // memory states at larger alias indexes. When merges grow, they are of course
4028 // filled with "top" in the unused in() positions.
4029 //
4030 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
4031 // (Top was chosen because it works smoothly with passes like GCM.)
4032 //
4033 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
4034 // the type of random VM bits like TLS references.) Since it is always the
4035 // first non-Bot memory slice, some low-level loops use it to initialize an
4036 // index variable: for (i = AliasIdxRaw; i < req(); i++).
4037 //
4038 //
4039 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
4040 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
4041 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
4042 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
4043 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
4044 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
4045 //
4046 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
4047 // really that different from the other memory inputs. An abbreviation called
4048 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
4049 //
4050 //
4051 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
4052 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
4053 // that "emerges though" the base memory will be marked as excluding the alias types
4054 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
4055 //
4056 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
4057 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
4058 //
4059 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
4060 // (It is currently unimplemented.) As you can see, the resulting merge is
4061 // actually a disjoint union of memory states, rather than an overlay.
4062 //
4063
4064 //------------------------------MergeMemNode-----------------------------------
4065 Node* MergeMemNode::make_empty_memory() {
4066 Node* empty_memory = (Node*) Compile::current()->top();
4067 assert(empty_memory->is_top(), "correct sentinel identity");
4068 return empty_memory;
4069 }
4070
4071 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
4072 init_class_id(Class_MergeMem);
4073 // all inputs are nullified in Node::Node(int)
4074 // set_input(0, NULL); // no control input
4075
4076 // Initialize the edges uniformly to top, for starters.
4077 Node* empty_mem = make_empty_memory();
4078 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
4079 init_req(i,empty_mem);
4080 }
4081 assert(empty_memory() == empty_mem, "");
4082
4083 if( new_base != NULL && new_base->is_MergeMem() ) {
4084 MergeMemNode* mdef = new_base->as_MergeMem();
4085 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
4086 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
4087 mms.set_memory(mms.memory2());
4088 }
4089 assert(base_memory() == mdef->base_memory(), "");
4090 } else {
4091 set_base_memory(new_base);
4092 }
4093 }
4094
4095 // Make a new, untransformed MergeMem with the same base as 'mem'.
4096 // If mem is itself a MergeMem, populate the result with the same edges.
4097 MergeMemNode* MergeMemNode::make(Node* mem) {
4098 return new MergeMemNode(mem);
4099 }
4100
4101 //------------------------------cmp--------------------------------------------
4102 uint MergeMemNode::hash() const { return NO_HASH; }
4103 uint MergeMemNode::cmp( const Node &n ) const {
4104 return (&n == this); // Always fail except on self
4105 }
4106
4107 //------------------------------Identity---------------------------------------
4108 Node* MergeMemNode::Identity(PhaseTransform *phase) {
4109 // Identity if this merge point does not record any interesting memory
4110 // disambiguations.
4111 Node* base_mem = base_memory();
4112 Node* empty_mem = empty_memory();
4113 if (base_mem != empty_mem) { // Memory path is not dead?
4114 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4115 Node* mem = in(i);
4116 if (mem != empty_mem && mem != base_mem) {
4117 return this; // Many memory splits; no change
4118 }
4119 }
4120 }
4121 return base_mem; // No memory splits; ID on the one true input
4122 }
4123
4124 //------------------------------Ideal------------------------------------------
4125 // This method is invoked recursively on chains of MergeMem nodes
4126 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4127 // Remove chain'd MergeMems
4128 //
4129 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
4130 // relative to the "in(Bot)". Since we are patching both at the same time,
4131 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
4132 // but rewrite each "in(i)" relative to the new "in(Bot)".
4133 Node *progress = NULL;
4134
4135
4136 Node* old_base = base_memory();
4137 Node* empty_mem = empty_memory();
4138 if (old_base == empty_mem)
4139 return NULL; // Dead memory path.
4140
4141 MergeMemNode* old_mbase;
4142 if (old_base != NULL && old_base->is_MergeMem())
4143 old_mbase = old_base->as_MergeMem();
4144 else
4145 old_mbase = NULL;
4146 Node* new_base = old_base;
4147
4148 // simplify stacked MergeMems in base memory
4149 if (old_mbase) new_base = old_mbase->base_memory();
4150
4151 // the base memory might contribute new slices beyond my req()
4152 if (old_mbase) grow_to_match(old_mbase);
4153
4154 // Look carefully at the base node if it is a phi.
4155 PhiNode* phi_base;
4156 if (new_base != NULL && new_base->is_Phi())
4157 phi_base = new_base->as_Phi();
4158 else
4159 phi_base = NULL;
4160
4161 Node* phi_reg = NULL;
4162 uint phi_len = (uint)-1;
4163 if (phi_base != NULL && !phi_base->is_copy()) {
4164 // do not examine phi if degraded to a copy
4165 phi_reg = phi_base->region();
4166 phi_len = phi_base->req();
4167 // see if the phi is unfinished
4168 for (uint i = 1; i < phi_len; i++) {
4169 if (phi_base->in(i) == NULL) {
4170 // incomplete phi; do not look at it yet!
4171 phi_reg = NULL;
4172 phi_len = (uint)-1;
4173 break;
4174 }
4175 }
4176 }
4177
4178 // Note: We do not call verify_sparse on entry, because inputs
4179 // can normalize to the base_memory via subsume_node or similar
4180 // mechanisms. This method repairs that damage.
4181
4182 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
4183
4184 // Look at each slice.
4185 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4186 Node* old_in = in(i);
4187 // calculate the old memory value
4188 Node* old_mem = old_in;
4189 if (old_mem == empty_mem) old_mem = old_base;
4190 assert(old_mem == memory_at(i), "");
4191
4192 // maybe update (reslice) the old memory value
4193
4194 // simplify stacked MergeMems
4195 Node* new_mem = old_mem;
4196 MergeMemNode* old_mmem;
4197 if (old_mem != NULL && old_mem->is_MergeMem())
4198 old_mmem = old_mem->as_MergeMem();
4199 else
4200 old_mmem = NULL;
4201 if (old_mmem == this) {
4202 // This can happen if loops break up and safepoints disappear.
4203 // A merge of BotPtr (default) with a RawPtr memory derived from a
4204 // safepoint can be rewritten to a merge of the same BotPtr with
4205 // the BotPtr phi coming into the loop. If that phi disappears
4206 // also, we can end up with a self-loop of the mergemem.
4207 // In general, if loops degenerate and memory effects disappear,
4208 // a mergemem can be left looking at itself. This simply means
4209 // that the mergemem's default should be used, since there is
4210 // no longer any apparent effect on this slice.
4211 // Note: If a memory slice is a MergeMem cycle, it is unreachable
4212 // from start. Update the input to TOP.
4213 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
4214 }
4215 else if (old_mmem != NULL) {
4216 new_mem = old_mmem->memory_at(i);
4217 }
4218 // else preceding memory was not a MergeMem
4219
4220 // replace equivalent phis (unfortunately, they do not GVN together)
4221 if (new_mem != NULL && new_mem != new_base &&
4222 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) {
4223 if (new_mem->is_Phi()) {
4224 PhiNode* phi_mem = new_mem->as_Phi();
4225 for (uint i = 1; i < phi_len; i++) {
4226 if (phi_base->in(i) != phi_mem->in(i)) {
4227 phi_mem = NULL;
4228 break;
4229 }
4230 }
4231 if (phi_mem != NULL) {
4232 // equivalent phi nodes; revert to the def
4233 new_mem = new_base;
4234 }
4235 }
4236 }
4237
4238 // maybe store down a new value
4239 Node* new_in = new_mem;
4240 if (new_in == new_base) new_in = empty_mem;
4241
4242 if (new_in != old_in) {
4243 // Warning: Do not combine this "if" with the previous "if"
4244 // A memory slice might have be be rewritten even if it is semantically
4245 // unchanged, if the base_memory value has changed.
4246 set_req(i, new_in);
4247 progress = this; // Report progress
4248 }
4249 }
4250
4251 if (new_base != old_base) {
4252 set_req(Compile::AliasIdxBot, new_base);
4253 // Don't use set_base_memory(new_base), because we need to update du.
4254 assert(base_memory() == new_base, "");
4255 progress = this;
4256 }
4257
4258 if( base_memory() == this ) {
4259 // a self cycle indicates this memory path is dead
4260 set_req(Compile::AliasIdxBot, empty_mem);
4261 }
4262
4263 // Resolve external cycles by calling Ideal on a MergeMem base_memory
4264 // Recursion must occur after the self cycle check above
4265 if( base_memory()->is_MergeMem() ) {
4266 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
4267 Node *m = phase->transform(new_mbase); // Rollup any cycles
4268 if( m != NULL && (m->is_top() ||
4269 m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem) ) {
4270 // propagate rollup of dead cycle to self
4271 set_req(Compile::AliasIdxBot, empty_mem);
4272 }
4273 }
4274
4275 if( base_memory() == empty_mem ) {
4276 progress = this;
4277 // Cut inputs during Parse phase only.
4278 // During Optimize phase a dead MergeMem node will be subsumed by Top.
4279 if( !can_reshape ) {
4280 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4281 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
4282 }
4283 }
4284 }
4285
4286 if( !progress && base_memory()->is_Phi() && can_reshape ) {
4287 // Check if PhiNode::Ideal's "Split phis through memory merges"
4288 // transform should be attempted. Look for this->phi->this cycle.
4289 uint merge_width = req();
4290 if (merge_width > Compile::AliasIdxRaw) {
4291 PhiNode* phi = base_memory()->as_Phi();
4292 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
4293 if (phi->in(i) == this) {
4294 phase->is_IterGVN()->_worklist.push(phi);
4295 break;
4296 }
4297 }
4298 }
4299 }
4300
4301 assert(progress || verify_sparse(), "please, no dups of base");
4302 return progress;
4303 }
4304
4305 //-------------------------set_base_memory-------------------------------------
4306 void MergeMemNode::set_base_memory(Node *new_base) {
4307 Node* empty_mem = empty_memory();
4308 set_req(Compile::AliasIdxBot, new_base);
4309 assert(memory_at(req()) == new_base, "must set default memory");
4310 // Clear out other occurrences of new_base:
4311 if (new_base != empty_mem) {
4312 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4313 if (in(i) == new_base) set_req(i, empty_mem);
4314 }
4315 }
4316 }
4317
4318 //------------------------------out_RegMask------------------------------------
4319 const RegMask &MergeMemNode::out_RegMask() const {
4320 return RegMask::Empty;
4321 }
4322
4323 //------------------------------dump_spec--------------------------------------
4324 #ifndef PRODUCT
4325 void MergeMemNode::dump_spec(outputStream *st) const {
4326 st->print(" {");
4327 Node* base_mem = base_memory();
4328 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
4329 Node* mem = (in(i) != NULL) ? memory_at(i) : base_mem;
4330 if (mem == base_mem) { st->print(" -"); continue; }
4331 st->print( " N%d:", mem->_idx );
4332 Compile::current()->get_adr_type(i)->dump_on(st);
4333 }
4334 st->print(" }");
4335 }
4336 #endif // !PRODUCT
4337
4338
4339 #ifdef ASSERT
4340 static bool might_be_same(Node* a, Node* b) {
4341 if (a == b) return true;
4342 if (!(a->is_Phi() || b->is_Phi())) return false;
4343 // phis shift around during optimization
4344 return true; // pretty stupid...
4345 }
4346
4347 // verify a narrow slice (either incoming or outgoing)
4348 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
4349 if (!VerifyAliases) return; // don't bother to verify unless requested
4350 if (is_error_reported()) return; // muzzle asserts when debugging an error
4351 if (Node::in_dump()) return; // muzzle asserts when printing
4352 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
4353 assert(n != NULL, "");
4354 // Elide intervening MergeMem's
4355 while (n->is_MergeMem()) {
4356 n = n->as_MergeMem()->memory_at(alias_idx);
4357 }
4358 Compile* C = Compile::current();
4359 const TypePtr* n_adr_type = n->adr_type();
4360 if (n == m->empty_memory()) {
4361 // Implicit copy of base_memory()
4362 } else if (n_adr_type != TypePtr::BOTTOM) {
4363 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type");
4364 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
4365 } else {
4366 // A few places like make_runtime_call "know" that VM calls are narrow,
4367 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
4368 bool expected_wide_mem = false;
4369 if (n == m->base_memory()) {
4370 expected_wide_mem = true;
4371 } else if (alias_idx == Compile::AliasIdxRaw ||
4372 n == m->memory_at(Compile::AliasIdxRaw)) {
4373 expected_wide_mem = true;
4374 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
4375 // memory can "leak through" calls on channels that
4376 // are write-once. Allow this also.
4377 expected_wide_mem = true;
4378 }
4379 assert(expected_wide_mem, "expected narrow slice replacement");
4380 }
4381 }
4382 #else // !ASSERT
4383 #define verify_memory_slice(m,i,n) (void)(0) // PRODUCT version is no-op
4384 #endif
4385
4386
4387 //-----------------------------memory_at---------------------------------------
4388 Node* MergeMemNode::memory_at(uint alias_idx) const {
4389 assert(alias_idx >= Compile::AliasIdxRaw ||
4390 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0,
4391 "must avoid base_memory and AliasIdxTop");
4392
4393 // Otherwise, it is a narrow slice.
4394 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
4395 Compile *C = Compile::current();
4396 if (is_empty_memory(n)) {
4397 // the array is sparse; empty slots are the "top" node
4398 n = base_memory();
4399 assert(Node::in_dump()
4400 || n == NULL || n->bottom_type() == Type::TOP
4401 || n->adr_type() == NULL // address is TOP
4402 || n->adr_type() == TypePtr::BOTTOM
4403 || n->adr_type() == TypeRawPtr::BOTTOM
4404 || Compile::current()->AliasLevel() == 0,
4405 "must be a wide memory");
4406 // AliasLevel == 0 if we are organizing the memory states manually.
4407 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
4408 } else {
4409 // make sure the stored slice is sane
4410 #ifdef ASSERT
4411 if (is_error_reported() || Node::in_dump()) {
4412 } else if (might_be_same(n, base_memory())) {
4413 // Give it a pass: It is a mostly harmless repetition of the base.
4414 // This can arise normally from node subsumption during optimization.
4415 } else {
4416 verify_memory_slice(this, alias_idx, n);
4417 }
4418 #endif
4419 }
4420 return n;
4421 }
4422
4423 //---------------------------set_memory_at-------------------------------------
4424 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
4425 verify_memory_slice(this, alias_idx, n);
4426 Node* empty_mem = empty_memory();
4427 if (n == base_memory()) n = empty_mem; // collapse default
4428 uint need_req = alias_idx+1;
4429 if (req() < need_req) {
4430 if (n == empty_mem) return; // already the default, so do not grow me
4431 // grow the sparse array
4432 do {
4433 add_req(empty_mem);
4434 } while (req() < need_req);
4435 }
4436 set_req( alias_idx, n );
4437 }
4438
4439
4440
4441 //--------------------------iteration_setup------------------------------------
4442 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
4443 if (other != NULL) {
4444 grow_to_match(other);
4445 // invariant: the finite support of mm2 is within mm->req()
4446 #ifdef ASSERT
4447 for (uint i = req(); i < other->req(); i++) {
4448 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
4449 }
4450 #endif
4451 }
4452 // Replace spurious copies of base_memory by top.
4453 Node* base_mem = base_memory();
4454 if (base_mem != NULL && !base_mem->is_top()) {
4455 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
4456 if (in(i) == base_mem)
4457 set_req(i, empty_memory());
4458 }
4459 }
4460 }
4461
4462 //---------------------------grow_to_match-------------------------------------
4463 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
4464 Node* empty_mem = empty_memory();
4465 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
4466 // look for the finite support of the other memory
4467 for (uint i = other->req(); --i >= req(); ) {
4468 if (other->in(i) != empty_mem) {
4469 uint new_len = i+1;
4470 while (req() < new_len) add_req(empty_mem);
4471 break;
4472 }
4473 }
4474 }
4475
4476 //---------------------------verify_sparse-------------------------------------
4477 #ifndef PRODUCT
4478 bool MergeMemNode::verify_sparse() const {
4479 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
4480 Node* base_mem = base_memory();
4481 // The following can happen in degenerate cases, since empty==top.
4482 if (is_empty_memory(base_mem)) return true;
4483 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4484 assert(in(i) != NULL, "sane slice");
4485 if (in(i) == base_mem) return false; // should have been the sentinel value!
4486 }
4487 return true;
4488 }
4489
4490 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
4491 Node* n;
4492 n = mm->in(idx);
4493 if (mem == n) return true; // might be empty_memory()
4494 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
4495 if (mem == n) return true;
4496 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) {
4497 if (mem == n) return true;
4498 if (n == NULL) break;
4499 }
4500 return false;
4501 }
4502 #endif // !PRODUCT