1 /*
2 * Copyright (c) 1997, 2016, 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/cfgnode.hpp"
32 #include "opto/compile.hpp"
33 #include "opto/connode.hpp"
34 #include "opto/loopnode.hpp"
35 #include "opto/machnode.hpp"
36 #include "opto/matcher.hpp"
37 #include "opto/memnode.hpp"
38 #include "opto/mulnode.hpp"
39 #include "opto/phaseX.hpp"
40 #include "opto/regmask.hpp"
41
42 // Portions of code courtesy of Clifford Click
43
44 // Optimization - Graph Style
45
46 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st);
47
48 //=============================================================================
49 uint MemNode::size_of() const { return sizeof(*this); }
50
51 const TypePtr *MemNode::adr_type() const {
52 Node* adr = in(Address);
53 const TypePtr* cross_check = NULL;
54 DEBUG_ONLY(cross_check = _adr_type);
55 return calculate_adr_type(adr->bottom_type(), cross_check);
56 }
57
58 #ifndef PRODUCT
59 void MemNode::dump_spec(outputStream *st) const {
60 if (in(Address) == NULL) return; // node is dead
61 #ifndef ASSERT
62 // fake the missing field
63 const TypePtr* _adr_type = NULL;
64 if (in(Address) != NULL)
65 _adr_type = in(Address)->bottom_type()->isa_ptr();
66 #endif
67 dump_adr_type(this, _adr_type, st);
68
69 Compile* C = Compile::current();
70 if( C->alias_type(_adr_type)->is_volatile() )
71 st->print(" Volatile!");
72 }
73
74 void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) {
75 st->print(" @");
76 if (adr_type == NULL) {
77 st->print("NULL");
78 } else {
79 adr_type->dump_on(st);
80 Compile* C = Compile::current();
81 Compile::AliasType* atp = NULL;
82 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type);
83 if (atp == NULL)
84 st->print(", idx=?\?;");
85 else if (atp->index() == Compile::AliasIdxBot)
86 st->print(", idx=Bot;");
87 else if (atp->index() == Compile::AliasIdxTop)
88 st->print(", idx=Top;");
89 else if (atp->index() == Compile::AliasIdxRaw)
90 st->print(", idx=Raw;");
91 else {
92 ciField* field = atp->field();
93 if (field) {
94 st->print(", name=");
95 field->print_name_on(st);
96 }
97 st->print(", idx=%d;", atp->index());
98 }
99 }
100 }
101
102 extern void print_alias_types();
103
104 #endif
105
106 Node *MemNode::optimize_simple_memory_chain(Node *mchain, const TypePtr *t_adr, PhaseGVN *phase) {
107 const TypeOopPtr *tinst = t_adr->isa_oopptr();
108 if (tinst == NULL || !tinst->is_known_instance_field())
109 return mchain; // don't try to optimize non-instance types
110 uint instance_id = tinst->instance_id();
111 Node *start_mem = phase->C->start()->proj_out(TypeFunc::Memory);
112 Node *prev = NULL;
113 Node *result = mchain;
114 while (prev != result) {
115 prev = result;
116 if (result == start_mem)
117 break; // hit one of our sentinels
118 // skip over a call which does not affect this memory slice
119 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {
120 Node *proj_in = result->in(0);
121 if (proj_in->is_Allocate() && proj_in->_idx == instance_id) {
122 break; // hit one of our sentinels
123 } else if (proj_in->is_Call()) {
124 CallNode *call = proj_in->as_Call();
125 if (!call->may_modify(t_adr, phase)) {
126 result = call->in(TypeFunc::Memory);
127 }
128 } else if (proj_in->is_Initialize()) {
129 AllocateNode* alloc = proj_in->as_Initialize()->allocation();
130 // Stop if this is the initialization for the object instance which
131 // which contains this memory slice, otherwise skip over it.
132 if (alloc != NULL && alloc->_idx != instance_id) {
133 result = proj_in->in(TypeFunc::Memory);
134 }
135 } else if (proj_in->is_MemBar()) {
136 result = proj_in->in(TypeFunc::Memory);
137 } else {
138 assert(false, "unexpected projection");
139 }
140 } else if (result->is_ClearArray()) {
141 if (!ClearArrayNode::step_through(&result, instance_id, phase)) {
142 // Can not bypass initialization of the instance
143 // we are looking for.
144 break;
145 }
146 // Otherwise skip it (the call updated 'result' value).
147 } else if (result->is_MergeMem()) {
148 result = step_through_mergemem(phase, result->as_MergeMem(), t_adr, NULL, tty);
149 }
150 }
151 return result;
152 }
153
154 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, PhaseGVN *phase) {
155 const TypeOopPtr *t_oop = t_adr->isa_oopptr();
156 bool is_instance = (t_oop != NULL) && t_oop->is_known_instance_field();
157 PhaseIterGVN *igvn = phase->is_IterGVN();
158 Node *result = mchain;
159 result = optimize_simple_memory_chain(result, t_adr, phase);
160 if (is_instance && igvn != NULL && result->is_Phi()) {
161 PhiNode *mphi = result->as_Phi();
162 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
163 const TypePtr *t = mphi->adr_type();
164 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
165 t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
166 t->is_oopptr()->cast_to_exactness(true)
167 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
168 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop) {
169 // clone the Phi with our address type
170 result = mphi->split_out_instance(t_adr, igvn);
171 } else {
172 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain");
173 }
174 }
175 return result;
176 }
177
178 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) {
179 uint alias_idx = phase->C->get_alias_index(tp);
180 Node *mem = mmem;
181 #ifdef ASSERT
182 {
183 // Check that current type is consistent with the alias index used during graph construction
184 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
185 bool consistent = adr_check == NULL || adr_check->empty() ||
186 phase->C->must_alias(adr_check, alias_idx );
187 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
188 if( !consistent && adr_check != NULL && !adr_check->empty() &&
189 tp->isa_aryptr() && tp->offset() == Type::OffsetBot &&
190 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot &&
191 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() ||
192 adr_check->offset() == oopDesc::klass_offset_in_bytes() ||
193 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) {
194 // don't assert if it is dead code.
195 consistent = true;
196 }
197 if( !consistent ) {
198 st->print("alias_idx==%d, adr_check==", alias_idx);
199 if( adr_check == NULL ) {
200 st->print("NULL");
201 } else {
202 adr_check->dump();
203 }
204 st->cr();
205 print_alias_types();
206 assert(consistent, "adr_check must match alias idx");
207 }
208 }
209 #endif
210 // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally
211 // means an array I have not precisely typed yet. Do not do any
212 // alias stuff with it any time soon.
213 const TypeOopPtr *toop = tp->isa_oopptr();
214 if( tp->base() != Type::AnyPtr &&
215 !(toop &&
216 toop->klass() != NULL &&
217 toop->klass()->is_java_lang_Object() &&
218 toop->offset() == Type::OffsetBot) ) {
219 // compress paths and change unreachable cycles to TOP
220 // If not, we can update the input infinitely along a MergeMem cycle
221 // Equivalent code in PhiNode::Ideal
222 Node* m = phase->transform(mmem);
223 // If transformed to a MergeMem, get the desired slice
224 // Otherwise the returned node represents memory for every slice
225 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
226 // Update input if it is progress over what we have now
227 }
228 return mem;
229 }
230
231 //--------------------------Ideal_common---------------------------------------
232 // Look for degenerate control and memory inputs. Bypass MergeMem inputs.
233 // Unhook non-raw memories from complete (macro-expanded) initializations.
234 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
235 // If our control input is a dead region, kill all below the region
236 Node *ctl = in(MemNode::Control);
237 if (ctl && remove_dead_region(phase, can_reshape))
238 return this;
239 ctl = in(MemNode::Control);
240 // Don't bother trying to transform a dead node
241 if( ctl && ctl->is_top() ) return NodeSentinel;
242
243 PhaseIterGVN *igvn = phase->is_IterGVN();
244 // Wait if control on the worklist.
245 if (ctl && can_reshape && igvn != NULL) {
246 Node* bol = NULL;
247 Node* cmp = NULL;
248 if (ctl->in(0)->is_If()) {
249 assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity");
250 bol = ctl->in(0)->in(1);
251 if (bol->is_Bool())
252 cmp = ctl->in(0)->in(1)->in(1);
253 }
254 if (igvn->_worklist.member(ctl) ||
255 (bol != NULL && igvn->_worklist.member(bol)) ||
256 (cmp != NULL && igvn->_worklist.member(cmp)) ) {
257 // This control path may be dead.
258 // Delay this memory node transformation until the control is processed.
259 phase->is_IterGVN()->_worklist.push(this);
260 return NodeSentinel; // caller will return NULL
261 }
262 }
263 // Ignore if memory is dead, or self-loop
264 Node *mem = in(MemNode::Memory);
265 if( phase->type( mem ) == Type::TOP ) return NodeSentinel; // caller will return NULL
266 assert( mem != this, "dead loop in MemNode::Ideal" );
267
268 if (can_reshape && igvn != NULL && igvn->_worklist.member(mem)) {
269 // This memory slice may be dead.
270 // Delay this mem node transformation until the memory is processed.
271 phase->is_IterGVN()->_worklist.push(this);
272 return NodeSentinel; // caller will return NULL
273 }
274
275 Node *address = in(MemNode::Address);
276 const Type *t_adr = phase->type( address );
277 if( t_adr == Type::TOP ) return NodeSentinel; // caller will return NULL
278
279 if( can_reshape && igvn != NULL &&
280 (igvn->_worklist.member(address) ||
281 igvn->_worklist.size() > 0 && (phase->type(address) != adr_type())) ) {
282 // The address's base and type may change when the address is processed.
283 // Delay this mem node transformation until the address is processed.
284 phase->is_IterGVN()->_worklist.push(this);
285 return NodeSentinel; // caller will return NULL
286 }
287
288 // Do NOT remove or optimize the next lines: ensure a new alias index
289 // is allocated for an oop pointer type before Escape Analysis.
290 // Note: C++ will not remove it since the call has side effect.
291 if ( t_adr->isa_oopptr() ) {
292 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr());
293 }
294
295 #ifdef ASSERT
296 Node* base = NULL;
297 if (address->is_AddP())
298 base = address->in(AddPNode::Base);
299 assert(base == NULL || t_adr->isa_rawptr() ||
300 !phase->type(base)->higher_equal(TypePtr::NULL_PTR), "NULL+offs not RAW address?");
301 #endif
302
303 // Avoid independent memory operations
304 Node* old_mem = mem;
305
306 // The code which unhooks non-raw memories from complete (macro-expanded)
307 // initializations was removed. After macro-expansion all stores catched
308 // by Initialize node became raw stores and there is no information
309 // which memory slices they modify. So it is unsafe to move any memory
310 // operation above these stores. Also in most cases hooked non-raw memories
311 // were already unhooked by using information from detect_ptr_independence()
312 // and find_previous_store().
313
314 if (mem->is_MergeMem()) {
315 MergeMemNode* mmem = mem->as_MergeMem();
316 const TypePtr *tp = t_adr->is_ptr();
317
318 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
319 }
320
321 if (mem != old_mem) {
322 set_req(MemNode::Memory, mem);
323 if (phase->type( mem ) == Type::TOP) return NodeSentinel;
324 return this;
325 }
326
327 // let the subclass continue analyzing...
328 return NULL;
329 }
330
331 // Helper function for proving some simple control dominations.
332 // Attempt to prove that all control inputs of 'dom' dominate 'sub'.
333 // Already assumes that 'dom' is available at 'sub', and that 'sub'
334 // is not a constant (dominated by the method's StartNode).
335 // Used by MemNode::find_previous_store to prove that the
336 // control input of a memory operation predates (dominates)
337 // an allocation it wants to look past.
338 bool MemNode::all_controls_dominate(Node* dom, Node* sub) {
339 if (dom == NULL || dom->is_top() || sub == NULL || sub->is_top())
340 return false; // Conservative answer for dead code
341
342 // Check 'dom'. Skip Proj and CatchProj nodes.
343 dom = dom->find_exact_control(dom);
344 if (dom == NULL || dom->is_top())
345 return false; // Conservative answer for dead code
346
347 if (dom == sub) {
348 // For the case when, for example, 'sub' is Initialize and the original
349 // 'dom' is Proj node of the 'sub'.
350 return false;
351 }
352
353 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub)
354 return true;
355
356 // 'dom' dominates 'sub' if its control edge and control edges
357 // of all its inputs dominate or equal to sub's control edge.
358
359 // Currently 'sub' is either Allocate, Initialize or Start nodes.
360 // Or Region for the check in LoadNode::Ideal();
361 // 'sub' should have sub->in(0) != NULL.
362 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() ||
363 sub->is_Region(), "expecting only these nodes");
364
365 // Get control edge of 'sub'.
366 Node* orig_sub = sub;
367 sub = sub->find_exact_control(sub->in(0));
368 if (sub == NULL || sub->is_top())
369 return false; // Conservative answer for dead code
370
371 assert(sub->is_CFG(), "expecting control");
372
373 if (sub == dom)
374 return true;
375
376 if (sub->is_Start() || sub->is_Root())
377 return false;
378
379 {
380 // Check all control edges of 'dom'.
381
382 ResourceMark rm;
383 Arena* arena = Thread::current()->resource_area();
384 Node_List nlist(arena);
385 Unique_Node_List dom_list(arena);
386
387 dom_list.push(dom);
388 bool only_dominating_controls = false;
389
390 for (uint next = 0; next < dom_list.size(); next++) {
391 Node* n = dom_list.at(next);
392 if (n == orig_sub)
393 return false; // One of dom's inputs dominated by sub.
394 if (!n->is_CFG() && n->pinned()) {
395 // Check only own control edge for pinned non-control nodes.
396 n = n->find_exact_control(n->in(0));
397 if (n == NULL || n->is_top())
398 return false; // Conservative answer for dead code
399 assert(n->is_CFG(), "expecting control");
400 dom_list.push(n);
401 } else if (n->is_Con() || n->is_Start() || n->is_Root()) {
402 only_dominating_controls = true;
403 } else if (n->is_CFG()) {
404 if (n->dominates(sub, nlist))
405 only_dominating_controls = true;
406 else
407 return false;
408 } else {
409 // First, own control edge.
410 Node* m = n->find_exact_control(n->in(0));
411 if (m != NULL) {
412 if (m->is_top())
413 return false; // Conservative answer for dead code
414 dom_list.push(m);
415 }
416 // Now, the rest of edges.
417 uint cnt = n->req();
418 for (uint i = 1; i < cnt; i++) {
419 m = n->find_exact_control(n->in(i));
420 if (m == NULL || m->is_top())
421 continue;
422 dom_list.push(m);
423 }
424 }
425 }
426 return only_dominating_controls;
427 }
428 }
429
430 //---------------------detect_ptr_independence---------------------------------
431 // Used by MemNode::find_previous_store to prove that two base
432 // pointers are never equal.
433 // The pointers are accompanied by their associated allocations,
434 // if any, which have been previously discovered by the caller.
435 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
436 Node* p2, AllocateNode* a2,
437 PhaseTransform* phase) {
438 // Attempt to prove that these two pointers cannot be aliased.
439 // They may both manifestly be allocations, and they should differ.
440 // Or, if they are not both allocations, they can be distinct constants.
441 // Otherwise, one is an allocation and the other a pre-existing value.
442 if (a1 == NULL && a2 == NULL) { // neither an allocation
443 return (p1 != p2) && p1->is_Con() && p2->is_Con();
444 } else if (a1 != NULL && a2 != NULL) { // both allocations
445 return (a1 != a2);
446 } else if (a1 != NULL) { // one allocation a1
447 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.)
448 return all_controls_dominate(p2, a1);
449 } else { //(a2 != NULL) // one allocation a2
450 return all_controls_dominate(p1, a2);
451 }
452 return false;
453 }
454
455
456 // The logic for reordering loads and stores uses four steps:
457 // (a) Walk carefully past stores and initializations which we
458 // can prove are independent of this load.
459 // (b) Observe that the next memory state makes an exact match
460 // with self (load or store), and locate the relevant store.
461 // (c) Ensure that, if we were to wire self directly to the store,
462 // the optimizer would fold it up somehow.
463 // (d) Do the rewiring, and return, depending on some other part of
464 // the optimizer to fold up the load.
465 // This routine handles steps (a) and (b). Steps (c) and (d) are
466 // specific to loads and stores, so they are handled by the callers.
467 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.)
468 //
469 Node* MemNode::find_previous_store(PhaseTransform* phase) {
470 Node* ctrl = in(MemNode::Control);
471 Node* adr = in(MemNode::Address);
472 intptr_t offset = 0;
473 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
474 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase);
475
476 if (offset == Type::OffsetBot)
477 return NULL; // cannot unalias unless there are precise offsets
478
479 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr();
480
481 intptr_t size_in_bytes = memory_size();
482
483 Node* mem = in(MemNode::Memory); // start searching here...
484
485 int cnt = 50; // Cycle limiter
486 for (;;) { // While we can dance past unrelated stores...
487 if (--cnt < 0) break; // Caught in cycle or a complicated dance?
488
489 if (mem->is_Store()) {
490 Node* st_adr = mem->in(MemNode::Address);
491 intptr_t st_offset = 0;
492 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
493 if (st_base == NULL)
494 break; // inscrutable pointer
495 if (st_offset != offset && st_offset != Type::OffsetBot) {
496 const int MAX_STORE = BytesPerLong;
497 if (st_offset >= offset + size_in_bytes ||
498 st_offset <= offset - MAX_STORE ||
499 st_offset <= offset - mem->as_Store()->memory_size()) {
500 // Success: The offsets are provably independent.
501 // (You may ask, why not just test st_offset != offset and be done?
502 // The answer is that stores of different sizes can co-exist
503 // in the same sequence of RawMem effects. We sometimes initialize
504 // a whole 'tile' of array elements with a single jint or jlong.)
505 mem = mem->in(MemNode::Memory);
506 continue; // (a) advance through independent store memory
507 }
508 }
509 if (st_base != base &&
510 detect_ptr_independence(base, alloc,
511 st_base,
512 AllocateNode::Ideal_allocation(st_base, phase),
513 phase)) {
514 // Success: The bases are provably independent.
515 mem = mem->in(MemNode::Memory);
516 continue; // (a) advance through independent store memory
517 }
518
519 // (b) At this point, if the bases or offsets do not agree, we lose,
520 // since we have not managed to prove 'this' and 'mem' independent.
521 if (st_base == base && st_offset == offset) {
522 return mem; // let caller handle steps (c), (d)
523 }
524
525 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
526 InitializeNode* st_init = mem->in(0)->as_Initialize();
527 AllocateNode* st_alloc = st_init->allocation();
528 if (st_alloc == NULL)
529 break; // something degenerated
530 bool known_identical = false;
531 bool known_independent = false;
532 if (alloc == st_alloc)
533 known_identical = true;
534 else if (alloc != NULL)
535 known_independent = true;
536 else if (all_controls_dominate(this, st_alloc))
537 known_independent = true;
538
539 if (known_independent) {
540 // The bases are provably independent: Either they are
541 // manifestly distinct allocations, or else the control
542 // of this load dominates the store's allocation.
543 int alias_idx = phase->C->get_alias_index(adr_type());
544 if (alias_idx == Compile::AliasIdxRaw) {
545 mem = st_alloc->in(TypeFunc::Memory);
546 } else {
547 mem = st_init->memory(alias_idx);
548 }
549 continue; // (a) advance through independent store memory
550 }
551
552 // (b) at this point, if we are not looking at a store initializing
553 // the same allocation we are loading from, we lose.
554 if (known_identical) {
555 // From caller, can_see_stored_value will consult find_captured_store.
556 return mem; // let caller handle steps (c), (d)
557 }
558
559 } else if (addr_t != NULL && addr_t->is_known_instance_field()) {
560 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
561 if (mem->is_Proj() && mem->in(0)->is_Call()) {
562 CallNode *call = mem->in(0)->as_Call();
563 if (!call->may_modify(addr_t, phase)) {
564 mem = call->in(TypeFunc::Memory);
565 continue; // (a) advance through independent call memory
566 }
567 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) {
568 mem = mem->in(0)->in(TypeFunc::Memory);
569 continue; // (a) advance through independent MemBar memory
570 } else if (mem->is_ClearArray()) {
571 if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) {
572 // (the call updated 'mem' value)
573 continue; // (a) advance through independent allocation memory
574 } else {
575 // Can not bypass initialization of the instance
576 // we are looking for.
577 return mem;
578 }
579 } else if (mem->is_MergeMem()) {
580 int alias_idx = phase->C->get_alias_index(adr_type());
581 mem = mem->as_MergeMem()->memory_at(alias_idx);
582 continue; // (a) advance through independent MergeMem memory
583 }
584 }
585
586 // Unless there is an explicit 'continue', we must bail out here,
587 // because 'mem' is an inscrutable memory state (e.g., a call).
588 break;
589 }
590
591 return NULL; // bail out
592 }
593
594 //----------------------calculate_adr_type-------------------------------------
595 // Helper function. Notices when the given type of address hits top or bottom.
596 // Also, asserts a cross-check of the type against the expected address type.
597 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
598 if (t == Type::TOP) return NULL; // does not touch memory any more?
599 #ifdef PRODUCT
600 cross_check = NULL;
601 #else
602 if (!VerifyAliases || is_error_reported() || Node::in_dump()) cross_check = NULL;
603 #endif
604 const TypePtr* tp = t->isa_ptr();
605 if (tp == NULL) {
606 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
607 return TypePtr::BOTTOM; // touches lots of memory
608 } else {
609 #ifdef ASSERT
610 // %%%% [phh] We don't check the alias index if cross_check is
611 // TypeRawPtr::BOTTOM. Needs to be investigated.
612 if (cross_check != NULL &&
613 cross_check != TypePtr::BOTTOM &&
614 cross_check != TypeRawPtr::BOTTOM) {
615 // Recheck the alias index, to see if it has changed (due to a bug).
616 Compile* C = Compile::current();
617 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
618 "must stay in the original alias category");
619 // The type of the address must be contained in the adr_type,
620 // disregarding "null"-ness.
621 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
622 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
623 assert(cross_check->meet(tp_notnull) == cross_check,
624 "real address must not escape from expected memory type");
625 }
626 #endif
627 return tp;
628 }
629 }
630
631 //------------------------adr_phi_is_loop_invariant----------------------------
632 // A helper function for Ideal_DU_postCCP to check if a Phi in a counted
633 // loop is loop invariant. Make a quick traversal of Phi and associated
634 // CastPP nodes, looking to see if they are a closed group within the loop.
635 bool MemNode::adr_phi_is_loop_invariant(Node* adr_phi, Node* cast) {
636 // The idea is that the phi-nest must boil down to only CastPP nodes
637 // with the same data. This implies that any path into the loop already
638 // includes such a CastPP, and so the original cast, whatever its input,
639 // must be covered by an equivalent cast, with an earlier control input.
640 ResourceMark rm;
641
642 // The loop entry input of the phi should be the unique dominating
643 // node for every Phi/CastPP in the loop.
644 Unique_Node_List closure;
645 closure.push(adr_phi->in(LoopNode::EntryControl));
646
647 // Add the phi node and the cast to the worklist.
648 Unique_Node_List worklist;
649 worklist.push(adr_phi);
650 if( cast != NULL ){
651 if( !cast->is_ConstraintCast() ) return false;
652 worklist.push(cast);
653 }
654
655 // Begin recursive walk of phi nodes.
656 while( worklist.size() ){
657 // Take a node off the worklist
658 Node *n = worklist.pop();
659 if( !closure.member(n) ){
660 // Add it to the closure.
661 closure.push(n);
662 // Make a sanity check to ensure we don't waste too much time here.
663 if( closure.size() > 20) return false;
664 // This node is OK if:
665 // - it is a cast of an identical value
666 // - or it is a phi node (then we add its inputs to the worklist)
667 // Otherwise, the node is not OK, and we presume the cast is not invariant
668 if( n->is_ConstraintCast() ){
669 worklist.push(n->in(1));
670 } else if( n->is_Phi() ) {
671 for( uint i = 1; i < n->req(); i++ ) {
672 worklist.push(n->in(i));
673 }
674 } else {
675 return false;
676 }
677 }
678 }
679
680 // Quit when the worklist is empty, and we've found no offending nodes.
681 return true;
682 }
683
684 //------------------------------Ideal_DU_postCCP-------------------------------
685 // Find any cast-away of null-ness and keep its control. Null cast-aways are
686 // going away in this pass and we need to make this memory op depend on the
687 // gating null check.
688 Node *MemNode::Ideal_DU_postCCP( PhaseCCP *ccp ) {
689 return Ideal_common_DU_postCCP(ccp, this, in(MemNode::Address));
690 }
691
692 // I tried to leave the CastPP's in. This makes the graph more accurate in
693 // some sense; we get to keep around the knowledge that an oop is not-null
694 // after some test. Alas, the CastPP's interfere with GVN (some values are
695 // the regular oop, some are the CastPP of the oop, all merge at Phi's which
696 // cannot collapse, etc). This cost us 10% on SpecJVM, even when I removed
697 // some of the more trivial cases in the optimizer. Removing more useless
698 // Phi's started allowing Loads to illegally float above null checks. I gave
699 // up on this approach. CNC 10/20/2000
700 // This static method may be called not from MemNode (EncodePNode calls it).
701 // Only the control edge of the node 'n' might be updated.
702 Node *MemNode::Ideal_common_DU_postCCP( PhaseCCP *ccp, Node* n, Node* adr ) {
703 Node *skipped_cast = NULL;
704 // Need a null check? Regular static accesses do not because they are
705 // from constant addresses. Array ops are gated by the range check (which
706 // always includes a NULL check). Just check field ops.
707 if( n->in(MemNode::Control) == NULL ) {
708 // Scan upwards for the highest location we can place this memory op.
709 while( true ) {
710 switch( adr->Opcode() ) {
711
712 case Op_AddP: // No change to NULL-ness, so peek thru AddP's
713 adr = adr->in(AddPNode::Base);
714 continue;
715
716 case Op_DecodeN: // No change to NULL-ness, so peek thru
717 adr = adr->in(1);
718 continue;
719
720 case Op_EncodeP:
721 // EncodeP node's control edge could be set by this method
722 // when EncodeP node depends on CastPP node.
723 //
724 // Use its control edge for memory op because EncodeP may go away
725 // later when it is folded with following or preceding DecodeN node.
726 if (adr->in(0) == NULL) {
727 // Keep looking for cast nodes.
728 adr = adr->in(1);
729 continue;
730 }
731 ccp->hash_delete(n);
732 n->set_req(MemNode::Control, adr->in(0));
733 ccp->hash_insert(n);
734 return n;
735
736 case Op_CastPP:
737 // If the CastPP is useless, just peek on through it.
738 if( ccp->type(adr) == ccp->type(adr->in(1)) ) {
739 // Remember the cast that we've peeked though. If we peek
740 // through more than one, then we end up remembering the highest
741 // one, that is, if in a loop, the one closest to the top.
742 skipped_cast = adr;
743 adr = adr->in(1);
744 continue;
745 }
746 // CastPP is going away in this pass! We need this memory op to be
747 // control-dependent on the test that is guarding the CastPP.
748 ccp->hash_delete(n);
749 n->set_req(MemNode::Control, adr->in(0));
750 ccp->hash_insert(n);
751 return n;
752
753 case Op_Phi:
754 // Attempt to float above a Phi to some dominating point.
755 if (adr->in(0) != NULL && adr->in(0)->is_CountedLoop()) {
756 // If we've already peeked through a Cast (which could have set the
757 // control), we can't float above a Phi, because the skipped Cast
758 // may not be loop invariant.
759 if (adr_phi_is_loop_invariant(adr, skipped_cast)) {
760 adr = adr->in(1);
761 continue;
762 }
763 }
764
765 // Intentional fallthrough!
766
767 // No obvious dominating point. The mem op is pinned below the Phi
768 // by the Phi itself. If the Phi goes away (no true value is merged)
769 // then the mem op can float, but not indefinitely. It must be pinned
770 // behind the controls leading to the Phi.
771 case Op_CheckCastPP:
772 // These usually stick around to change address type, however a
773 // useless one can be elided and we still need to pick up a control edge
774 if (adr->in(0) == NULL) {
775 // This CheckCastPP node has NO control and is likely useless. But we
776 // need check further up the ancestor chain for a control input to keep
777 // the node in place. 4959717.
778 skipped_cast = adr;
779 adr = adr->in(1);
780 continue;
781 }
782 ccp->hash_delete(n);
783 n->set_req(MemNode::Control, adr->in(0));
784 ccp->hash_insert(n);
785 return n;
786
787 // List of "safe" opcodes; those that implicitly block the memory
788 // op below any null check.
789 case Op_CastX2P: // no null checks on native pointers
790 case Op_Parm: // 'this' pointer is not null
791 case Op_LoadP: // Loading from within a klass
792 case Op_LoadN: // Loading from within a klass
793 case Op_LoadKlass: // Loading from within a klass
794 case Op_LoadNKlass: // Loading from within a klass
795 case Op_ConP: // Loading from a klass
796 case Op_ConN: // Loading from a klass
797 case Op_CreateEx: // Sucking up the guts of an exception oop
798 case Op_Con: // Reading from TLS
799 case Op_CMoveP: // CMoveP is pinned
800 case Op_CMoveN: // CMoveN is pinned
801 break; // No progress
802
803 case Op_Proj: // Direct call to an allocation routine
804 case Op_SCMemProj: // Memory state from store conditional ops
805 #ifdef ASSERT
806 {
807 assert(adr->as_Proj()->_con == TypeFunc::Parms, "must be return value");
808 const Node* call = adr->in(0);
809 if (call->is_CallJava()) {
810 const CallJavaNode* call_java = call->as_CallJava();
811 const TypeTuple *r = call_java->tf()->range();
812 assert(r->cnt() > TypeFunc::Parms, "must return value");
813 const Type* ret_type = r->field_at(TypeFunc::Parms);
814 assert(ret_type && ret_type->isa_ptr(), "must return pointer");
815 // We further presume that this is one of
816 // new_instance_Java, new_array_Java, or
817 // the like, but do not assert for this.
818 } else if (call->is_Allocate()) {
819 // similar case to new_instance_Java, etc.
820 } else if (!call->is_CallLeaf()) {
821 // Projections from fetch_oop (OSR) are allowed as well.
822 ShouldNotReachHere();
823 }
824 }
825 #endif
826 break;
827 default:
828 ShouldNotReachHere();
829 }
830 break;
831 }
832 }
833
834 return NULL; // No progress
835 }
836
837
838 //=============================================================================
839 uint LoadNode::size_of() const { return sizeof(*this); }
840 uint LoadNode::cmp( const Node &n ) const
841 { return !Type::cmp( _type, ((LoadNode&)n)._type ); }
842 const Type *LoadNode::bottom_type() const { return _type; }
843 uint LoadNode::ideal_reg() const {
844 return Matcher::base2reg[_type->base()];
845 }
846
847 #ifndef PRODUCT
848 void LoadNode::dump_spec(outputStream *st) const {
849 MemNode::dump_spec(st);
850 if( !Verbose && !WizardMode ) {
851 // standard dump does this in Verbose and WizardMode
852 st->print(" #"); _type->dump_on(st);
853 }
854 }
855 #endif
856
857 #ifdef ASSERT
858 //----------------------------is_immutable_value-------------------------------
859 // Helper function to allow a raw load without control edge for some cases
860 bool LoadNode::is_immutable_value(Node* adr) {
861 return (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() &&
862 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal &&
863 (adr->in(AddPNode::Offset)->find_intptr_t_con(-1) ==
864 in_bytes(JavaThread::osthread_offset())));
865 }
866 #endif
867
868 //----------------------------LoadNode::make-----------------------------------
869 // Polymorphic factory method:
870 Node *LoadNode::make( PhaseGVN& gvn, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt ) {
871 Compile* C = gvn.C;
872
873 // sanity check the alias category against the created node type
874 assert(!(adr_type->isa_oopptr() &&
875 adr_type->offset() == oopDesc::klass_offset_in_bytes()),
876 "use LoadKlassNode instead");
877 assert(!(adr_type->isa_aryptr() &&
878 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
879 "use LoadRangeNode instead");
880 // Check control edge of raw loads
881 assert( ctl != NULL || C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
882 // oop will be recorded in oop map if load crosses safepoint
883 rt->isa_oopptr() || is_immutable_value(adr),
884 "raw memory operations should have control edge");
885 switch (bt) {
886 case T_BOOLEAN: return new (C) LoadUBNode(ctl, mem, adr, adr_type, rt->is_int() );
887 case T_BYTE: return new (C) LoadBNode (ctl, mem, adr, adr_type, rt->is_int() );
888 case T_INT: return new (C) LoadINode (ctl, mem, adr, adr_type, rt->is_int() );
889 case T_CHAR: return new (C) LoadUSNode(ctl, mem, adr, adr_type, rt->is_int() );
890 case T_SHORT: return new (C) LoadSNode (ctl, mem, adr, adr_type, rt->is_int() );
891 case T_LONG: return new (C) LoadLNode (ctl, mem, adr, adr_type, rt->is_long() );
892 case T_FLOAT: return new (C) LoadFNode (ctl, mem, adr, adr_type, rt );
893 case T_DOUBLE: return new (C) LoadDNode (ctl, mem, adr, adr_type, rt );
894 case T_ADDRESS: return new (C) LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr() );
895 case T_OBJECT:
896 #ifdef _LP64
897 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
898 Node* load = gvn.transform(new (C) LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop()));
899 return new (C) DecodeNNode(load, load->bottom_type()->make_ptr());
900 } else
901 #endif
902 {
903 assert(!adr->bottom_type()->is_ptr_to_narrowoop(), "should have got back a narrow oop");
904 return new (C) LoadPNode(ctl, mem, adr, adr_type, rt->is_oopptr());
905 }
906 }
907 ShouldNotReachHere();
908 return (LoadNode*)NULL;
909 }
910
911 LoadLNode* LoadLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt) {
912 bool require_atomic = true;
913 return new (C) LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), require_atomic);
914 }
915
916
917
918
919 //------------------------------hash-------------------------------------------
920 uint LoadNode::hash() const {
921 // unroll addition of interesting fields
922 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
923 }
924
925 //---------------------------can_see_stored_value------------------------------
926 // This routine exists to make sure this set of tests is done the same
927 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
928 // will change the graph shape in a way which makes memory alive twice at the
929 // same time (uses the Oracle model of aliasing), then some
930 // LoadXNode::Identity will fold things back to the equivalence-class model
931 // of aliasing.
932 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const {
933 Node* ld_adr = in(MemNode::Address);
934
935 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
936 Compile::AliasType* atp = tp != NULL ? phase->C->alias_type(tp) : NULL;
937 if (EliminateAutoBox && atp != NULL && atp->index() >= Compile::AliasIdxRaw &&
938 atp->field() != NULL && !atp->field()->is_volatile()) {
939 uint alias_idx = atp->index();
940 bool final = atp->field()->is_final();
941 Node* result = NULL;
942 Node* current = st;
943 // Skip through chains of MemBarNodes checking the MergeMems for
944 // new states for the slice of this load. Stop once any other
945 // kind of node is encountered. Loads from final memory can skip
946 // through any kind of MemBar but normal loads shouldn't skip
947 // through MemBarAcquire since the could allow them to move out of
948 // a synchronized region.
949 while (current->is_Proj()) {
950 int opc = current->in(0)->Opcode();
951 if ((final && (opc == Op_MemBarAcquire || opc == Op_MemBarAcquireLock)) ||
952 opc == Op_MemBarRelease || opc == Op_MemBarCPUOrder ||
953 opc == Op_MemBarReleaseLock) {
954 Node* mem = current->in(0)->in(TypeFunc::Memory);
955 if (mem->is_MergeMem()) {
956 MergeMemNode* merge = mem->as_MergeMem();
957 Node* new_st = merge->memory_at(alias_idx);
958 if (new_st == merge->base_memory()) {
959 // Keep searching
960 current = merge->base_memory();
961 continue;
962 }
963 // Save the new memory state for the slice and fall through
964 // to exit.
965 result = new_st;
966 }
967 }
968 break;
969 }
970 if (result != NULL) {
971 st = result;
972 }
973 }
974
975
976 // Loop around twice in the case Load -> Initialize -> Store.
977 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
978 for (int trip = 0; trip <= 1; trip++) {
979
980 if (st->is_Store()) {
981 Node* st_adr = st->in(MemNode::Address);
982 if (!phase->eqv(st_adr, ld_adr)) {
983 // Try harder before giving up... Match raw and non-raw pointers.
984 intptr_t st_off = 0;
985 AllocateNode* alloc = AllocateNode::Ideal_allocation(st_adr, phase, st_off);
986 if (alloc == NULL) return NULL;
987 intptr_t ld_off = 0;
988 AllocateNode* allo2 = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
989 if (alloc != allo2) return NULL;
990 if (ld_off != st_off) return NULL;
991 // At this point we have proven something like this setup:
992 // A = Allocate(...)
993 // L = LoadQ(, AddP(CastPP(, A.Parm),, #Off))
994 // S = StoreQ(, AddP(, A.Parm , #Off), V)
995 // (Actually, we haven't yet proven the Q's are the same.)
996 // In other words, we are loading from a casted version of
997 // the same pointer-and-offset that we stored to.
998 // Thus, we are able to replace L by V.
999 }
1000 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
1001 if (store_Opcode() != st->Opcode())
1002 return NULL;
1003 return st->in(MemNode::ValueIn);
1004 }
1005
1006 intptr_t offset = 0; // scratch
1007
1008 // A load from a freshly-created object always returns zero.
1009 // (This can happen after LoadNode::Ideal resets the load's memory input
1010 // to find_captured_store, which returned InitializeNode::zero_memory.)
1011 if (st->is_Proj() && st->in(0)->is_Allocate() &&
1012 st->in(0) == AllocateNode::Ideal_allocation(ld_adr, phase, offset) &&
1013 offset >= st->in(0)->as_Allocate()->minimum_header_size()) {
1014 // return a zero value for the load's basic type
1015 // (This is one of the few places where a generic PhaseTransform
1016 // can create new nodes. Think of it as lazily manifesting
1017 // virtually pre-existing constants.)
1018 return phase->zerocon(memory_type());
1019 }
1020
1021 // A load from an initialization barrier can match a captured store.
1022 if (st->is_Proj() && st->in(0)->is_Initialize()) {
1023 InitializeNode* init = st->in(0)->as_Initialize();
1024 AllocateNode* alloc = init->allocation();
1025 if (alloc != NULL &&
1026 alloc == AllocateNode::Ideal_allocation(ld_adr, phase, offset)) {
1027 // examine a captured store value
1028 st = init->find_captured_store(offset, memory_size(), phase);
1029 if (st != NULL)
1030 continue; // take one more trip around
1031 }
1032 }
1033
1034 break;
1035 }
1036
1037 return NULL;
1038 }
1039
1040 //----------------------is_instance_field_load_with_local_phi------------------
1041 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
1042 if( in(MemNode::Memory)->is_Phi() && in(MemNode::Memory)->in(0) == ctrl &&
1043 in(MemNode::Address)->is_AddP() ) {
1044 const TypeOopPtr* t_oop = in(MemNode::Address)->bottom_type()->isa_oopptr();
1045 // Only instances.
1046 if( t_oop != NULL && t_oop->is_known_instance_field() &&
1047 t_oop->offset() != Type::OffsetBot &&
1048 t_oop->offset() != Type::OffsetTop) {
1049 return true;
1050 }
1051 }
1052 return false;
1053 }
1054
1055 //------------------------------Identity---------------------------------------
1056 // Loads are identity if previous store is to same address
1057 Node *LoadNode::Identity( PhaseTransform *phase ) {
1058 // If the previous store-maker is the right kind of Store, and the store is
1059 // to the same address, then we are equal to the value stored.
1060 Node* mem = in(MemNode::Memory);
1061 Node* value = can_see_stored_value(mem, phase);
1062 if( value ) {
1063 // byte, short & char stores truncate naturally.
1064 // A load has to load the truncated value which requires
1065 // some sort of masking operation and that requires an
1066 // Ideal call instead of an Identity call.
1067 if (memory_size() < BytesPerInt) {
1068 // If the input to the store does not fit with the load's result type,
1069 // it must be truncated via an Ideal call.
1070 if (!phase->type(value)->higher_equal(phase->type(this)))
1071 return this;
1072 }
1073 // (This works even when value is a Con, but LoadNode::Value
1074 // usually runs first, producing the singleton type of the Con.)
1075 return value;
1076 }
1077
1078 // Search for an existing data phi which was generated before for the same
1079 // instance's field to avoid infinite generation of phis in a loop.
1080 Node *region = mem->in(0);
1081 if (is_instance_field_load_with_local_phi(region)) {
1082 const TypePtr *addr_t = in(MemNode::Address)->bottom_type()->isa_ptr();
1083 int this_index = phase->C->get_alias_index(addr_t);
1084 int this_offset = addr_t->offset();
1085 int this_id = addr_t->is_oopptr()->instance_id();
1086 const Type* this_type = bottom_type();
1087 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1088 Node* phi = region->fast_out(i);
1089 if (phi->is_Phi() && phi != mem &&
1090 phi->as_Phi()->is_same_inst_field(this_type, this_id, this_index, this_offset)) {
1091 return phi;
1092 }
1093 }
1094 }
1095
1096 return this;
1097 }
1098
1099
1100 // Returns true if the AliasType refers to the field that holds the
1101 // cached box array. Currently only handles the IntegerCache case.
1102 static bool is_autobox_cache(Compile::AliasType* atp) {
1103 if (atp != NULL && atp->field() != NULL) {
1104 ciField* field = atp->field();
1105 ciSymbol* klass = field->holder()->name();
1106 if (field->name() == ciSymbol::cache_field_name() &&
1107 field->holder()->uses_default_loader() &&
1108 klass == ciSymbol::java_lang_Integer_IntegerCache()) {
1109 return true;
1110 }
1111 }
1112 return false;
1113 }
1114
1115 // Fetch the base value in the autobox array
1116 static bool fetch_autobox_base(Compile::AliasType* atp, int& cache_offset) {
1117 if (atp != NULL && atp->field() != NULL) {
1118 ciField* field = atp->field();
1119 ciSymbol* klass = field->holder()->name();
1120 if (field->name() == ciSymbol::cache_field_name() &&
1121 field->holder()->uses_default_loader() &&
1122 klass == ciSymbol::java_lang_Integer_IntegerCache()) {
1123 assert(field->is_constant(), "what?");
1124 ciObjArray* array = field->constant_value().as_object()->as_obj_array();
1125 // Fetch the box object at the base of the array and get its value
1126 ciInstance* box = array->obj_at(0)->as_instance();
1127 ciInstanceKlass* ik = box->klass()->as_instance_klass();
1128 if (ik->nof_nonstatic_fields() == 1) {
1129 // This should be true nonstatic_field_at requires calling
1130 // nof_nonstatic_fields so check it anyway
1131 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1132 cache_offset = c.as_int();
1133 }
1134 return true;
1135 }
1136 }
1137 return false;
1138 }
1139
1140 // Returns true if the AliasType refers to the value field of an
1141 // autobox object. Currently only handles Integer.
1142 static bool is_autobox_object(Compile::AliasType* atp) {
1143 if (atp != NULL && atp->field() != NULL) {
1144 ciField* field = atp->field();
1145 ciSymbol* klass = field->holder()->name();
1146 if (field->name() == ciSymbol::value_name() &&
1147 field->holder()->uses_default_loader() &&
1148 klass == ciSymbol::java_lang_Integer()) {
1149 return true;
1150 }
1151 }
1152 return false;
1153 }
1154
1155
1156 // We're loading from an object which has autobox behaviour.
1157 // If this object is result of a valueOf call we'll have a phi
1158 // merging a newly allocated object and a load from the cache.
1159 // We want to replace this load with the original incoming
1160 // argument to the valueOf call.
1161 Node* LoadNode::eliminate_autobox(PhaseGVN* phase) {
1162 Node* base = in(Address)->in(AddPNode::Base);
1163 if (base->is_Phi() && base->req() == 3) {
1164 AllocateNode* allocation = NULL;
1165 int allocation_index = -1;
1166 int load_index = -1;
1167 for (uint i = 1; i < base->req(); i++) {
1168 allocation = AllocateNode::Ideal_allocation(base->in(i), phase);
1169 if (allocation != NULL) {
1170 allocation_index = i;
1171 load_index = 3 - allocation_index;
1172 break;
1173 }
1174 }
1175 bool has_load = ( allocation != NULL &&
1176 (base->in(load_index)->is_Load() ||
1177 base->in(load_index)->is_DecodeN() &&
1178 base->in(load_index)->in(1)->is_Load()) );
1179 if (has_load && in(Memory)->is_Phi() && in(Memory)->in(0) == base->in(0)) {
1180 // Push the loads from the phi that comes from valueOf up
1181 // through it to allow elimination of the loads and the recovery
1182 // of the original value.
1183 Node* mem_phi = in(Memory);
1184 Node* offset = in(Address)->in(AddPNode::Offset);
1185 Node* region = base->in(0);
1186
1187 Node* in1 = clone();
1188 Node* in1_addr = in1->in(Address)->clone();
1189 in1_addr->set_req(AddPNode::Base, base->in(allocation_index));
1190 in1_addr->set_req(AddPNode::Address, base->in(allocation_index));
1191 in1_addr->set_req(AddPNode::Offset, offset);
1192 in1->set_req(0, region->in(allocation_index));
1193 in1->set_req(Address, in1_addr);
1194 in1->set_req(Memory, mem_phi->in(allocation_index));
1195
1196 Node* in2 = clone();
1197 Node* in2_addr = in2->in(Address)->clone();
1198 in2_addr->set_req(AddPNode::Base, base->in(load_index));
1199 in2_addr->set_req(AddPNode::Address, base->in(load_index));
1200 in2_addr->set_req(AddPNode::Offset, offset);
1201 in2->set_req(0, region->in(load_index));
1202 in2->set_req(Address, in2_addr);
1203 in2->set_req(Memory, mem_phi->in(load_index));
1204
1205 in1_addr = phase->transform(in1_addr);
1206 in1 = phase->transform(in1);
1207 in2_addr = phase->transform(in2_addr);
1208 in2 = phase->transform(in2);
1209
1210 PhiNode* result = PhiNode::make_blank(region, this);
1211 result->set_req(allocation_index, in1);
1212 result->set_req(load_index, in2);
1213 return result;
1214 }
1215 } else if (base->is_Load() ||
1216 base->is_DecodeN() && base->in(1)->is_Load()) {
1217 if (base->is_DecodeN()) {
1218 // Get LoadN node which loads cached Integer object
1219 base = base->in(1);
1220 }
1221 // Eliminate the load of Integer.value for integers from the cache
1222 // array by deriving the value from the index into the array.
1223 // Capture the offset of the load and then reverse the computation.
1224 Node* load_base = base->in(Address)->in(AddPNode::Base);
1225 if (load_base->is_DecodeN()) {
1226 // Get LoadN node which loads IntegerCache.cache field
1227 load_base = load_base->in(1);
1228 }
1229 if (load_base != NULL) {
1230 Compile::AliasType* atp = phase->C->alias_type(load_base->adr_type());
1231 intptr_t cache_offset;
1232 int shift = -1;
1233 Node* cache = NULL;
1234 if (is_autobox_cache(atp)) {
1235 shift = exact_log2(type2aelembytes(T_OBJECT));
1236 cache = AddPNode::Ideal_base_and_offset(load_base->in(Address), phase, cache_offset);
1237 }
1238 if (cache != NULL && base->in(Address)->is_AddP()) {
1239 Node* elements[4];
1240 int count = base->in(Address)->as_AddP()->unpack_offsets(elements, ARRAY_SIZE(elements));
1241 int cache_low;
1242 if (count > 0 && fetch_autobox_base(atp, cache_low)) {
1243 int offset = arrayOopDesc::base_offset_in_bytes(memory_type()) - (cache_low << shift);
1244 // Add up all the offsets making of the address of the load
1245 Node* result = elements[0];
1246 for (int i = 1; i < count; i++) {
1247 result = phase->transform(new (phase->C) AddXNode(result, elements[i]));
1248 }
1249 // Remove the constant offset from the address and then
1250 // remove the scaling of the offset to recover the original index.
1251 result = phase->transform(new (phase->C) AddXNode(result, phase->MakeConX(-offset)));
1252 if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) {
1253 // Peel the shift off directly but wrap it in a dummy node
1254 // since Ideal can't return existing nodes
1255 result = new (phase->C) RShiftXNode(result->in(1), phase->intcon(0));
1256 } else {
1257 result = new (phase->C) RShiftXNode(result, phase->intcon(shift));
1258 }
1259 #ifdef _LP64
1260 result = new (phase->C) ConvL2INode(phase->transform(result));
1261 #endif
1262 return result;
1263 }
1264 }
1265 }
1266 }
1267 return NULL;
1268 }
1269
1270 //------------------------------split_through_phi------------------------------
1271 // Split instance field load through Phi.
1272 Node *LoadNode::split_through_phi(PhaseGVN *phase) {
1273 Node* mem = in(MemNode::Memory);
1274 Node* address = in(MemNode::Address);
1275 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1276 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1277
1278 assert(mem->is_Phi() && (t_oop != NULL) &&
1279 t_oop->is_known_instance_field(), "invalide conditions");
1280
1281 Node *region = mem->in(0);
1282 if (region == NULL) {
1283 return NULL; // Wait stable graph
1284 }
1285 uint cnt = mem->req();
1286 for (uint i = 1; i < cnt; i++) {
1287 Node* rc = region->in(i);
1288 if (rc == NULL || phase->type(rc) == Type::TOP)
1289 return NULL; // Wait stable graph
1290 Node *in = mem->in(i);
1291 if (in == NULL) {
1292 return NULL; // Wait stable graph
1293 }
1294 }
1295 // Check for loop invariant.
1296 if (cnt == 3) {
1297 for (uint i = 1; i < cnt; i++) {
1298 Node *in = mem->in(i);
1299 Node* m = MemNode::optimize_memory_chain(in, addr_t, phase);
1300 if (m == mem) {
1301 set_req(MemNode::Memory, mem->in(cnt - i)); // Skip this phi.
1302 return this;
1303 }
1304 }
1305 }
1306 // Split through Phi (see original code in loopopts.cpp).
1307 assert(phase->C->have_alias_type(addr_t), "instance should have alias type");
1308
1309 // Do nothing here if Identity will find a value
1310 // (to avoid infinite chain of value phis generation).
1311 if (!phase->eqv(this, this->Identity(phase)))
1312 return NULL;
1313
1314 // Skip the split if the region dominates some control edge of the address.
1315 if (!MemNode::all_controls_dominate(address, region))
1316 return NULL;
1317
1318 const Type* this_type = this->bottom_type();
1319 int this_index = phase->C->get_alias_index(addr_t);
1320 int this_offset = addr_t->offset();
1321 int this_iid = addr_t->is_oopptr()->instance_id();
1322 PhaseIterGVN *igvn = phase->is_IterGVN();
1323 Node *phi = new (igvn->C) 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) == phase->C->top()) {
1328 x = phase->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 for (uint j = 1; j < this->req(); j++) {
1339 Node *in = this->in(j);
1340 if (in->is_Phi() && in->in(0) == region)
1341 x->set_req(j, in->in(i)); // Use pre-Phi input for the clone
1342 }
1343 }
1344 // Check for a 'win' on some paths
1345 const Type *t = x->Value(igvn);
1346
1347 bool singleton = t->singleton();
1348
1349 // See comments in PhaseIdealLoop::split_thru_phi().
1350 if (singleton && t == Type::TOP) {
1351 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1352 }
1353
1354 if (singleton) {
1355 x = igvn->makecon(t);
1356 } else {
1357 // We now call Identity to try to simplify the cloned node.
1358 // Note that some Identity methods call phase->type(this).
1359 // Make sure that the type array is big enough for
1360 // our new node, even though we may throw the node away.
1361 // (This tweaking with igvn only works because x is a new node.)
1362 igvn->set_type(x, t);
1363 // If x is a TypeNode, capture any more-precise type permanently into Node
1364 // otherwise it will be not updated during igvn->transform since
1365 // igvn->type(x) is set to x->Value() already.
1366 x->raise_bottom_type(t);
1367 Node *y = x->Identity(igvn);
1368 if (y != x) {
1369 x = y;
1370 } else {
1371 y = igvn->hash_find(x);
1372 if (y) {
1373 x = y;
1374 } else {
1375 // Else x is a new node we are keeping
1376 // We do not need register_new_node_with_optimizer
1377 // because set_type has already been called.
1378 igvn->_worklist.push(x);
1379 }
1380 }
1381 }
1382 if (x != the_clone && the_clone != NULL)
1383 igvn->remove_dead_node(the_clone);
1384 phi->set_req(i, x);
1385 }
1386 // Record Phi
1387 igvn->register_new_node_with_optimizer(phi);
1388 return phi;
1389 }
1390
1391 //------------------------------Ideal------------------------------------------
1392 // If the load is from Field memory and the pointer is non-null, we can
1393 // zero out the control input.
1394 // If the offset is constant and the base is an object allocation,
1395 // try to hook me up to the exact initializing store.
1396 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1397 Node* p = MemNode::Ideal_common(phase, can_reshape);
1398 if (p) return (p == NodeSentinel) ? NULL : p;
1399
1400 Node* ctrl = in(MemNode::Control);
1401 Node* address = in(MemNode::Address);
1402
1403 // Skip up past a SafePoint control. Cannot do this for Stores because
1404 // pointer stores & cardmarks must stay on the same side of a SafePoint.
1405 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint &&
1406 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw ) {
1407 ctrl = ctrl->in(0);
1408 set_req(MemNode::Control,ctrl);
1409 }
1410
1411 intptr_t ignore = 0;
1412 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1413 if (base != NULL
1414 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
1415 // Check for useless control edge in some common special cases
1416 if (in(MemNode::Control) != NULL
1417 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1418 && all_controls_dominate(base, phase->C->start())) {
1419 // A method-invariant, non-null address (constant or 'this' argument).
1420 set_req(MemNode::Control, NULL);
1421 }
1422
1423 if (EliminateAutoBox && can_reshape) {
1424 assert(!phase->type(base)->higher_equal(TypePtr::NULL_PTR), "the autobox pointer should be non-null");
1425 Compile::AliasType* atp = phase->C->alias_type(adr_type());
1426 if (is_autobox_object(atp)) {
1427 Node* result = eliminate_autobox(phase);
1428 if (result != NULL) return result;
1429 }
1430 }
1431 }
1432
1433 Node* mem = in(MemNode::Memory);
1434 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1435
1436 if (addr_t != NULL) {
1437 // try to optimize our memory input
1438 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, phase);
1439 if (opt_mem != mem) {
1440 set_req(MemNode::Memory, opt_mem);
1441 if (phase->type( opt_mem ) == Type::TOP) return NULL;
1442 return this;
1443 }
1444 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1445 if (can_reshape && opt_mem->is_Phi() &&
1446 (t_oop != NULL) && t_oop->is_known_instance_field()) {
1447 PhaseIterGVN *igvn = phase->is_IterGVN();
1448 if (igvn != NULL && igvn->_worklist.member(opt_mem)) {
1449 // Delay this transformation until memory Phi is processed.
1450 phase->is_IterGVN()->_worklist.push(this);
1451 return NULL;
1452 }
1453 // Split instance field load through Phi.
1454 Node* result = split_through_phi(phase);
1455 if (result != NULL) return result;
1456 }
1457 }
1458
1459 // Check for prior store with a different base or offset; make Load
1460 // independent. Skip through any number of them. Bail out if the stores
1461 // are in an endless dead cycle and report no progress. This is a key
1462 // transform for Reflection. However, if after skipping through the Stores
1463 // we can't then fold up against a prior store do NOT do the transform as
1464 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
1465 // array memory alive twice: once for the hoisted Load and again after the
1466 // bypassed Store. This situation only works if EVERYBODY who does
1467 // anti-dependence work knows how to bypass. I.e. we need all
1468 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
1469 // the alias index stuff. So instead, peek through Stores and IFF we can
1470 // fold up, do so.
1471 Node* prev_mem = find_previous_store(phase);
1472 // Steps (a), (b): Walk past independent stores to find an exact match.
1473 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) {
1474 // (c) See if we can fold up on the spot, but don't fold up here.
1475 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
1476 // just return a prior value, which is done by Identity calls.
1477 if (can_see_stored_value(prev_mem, phase)) {
1478 // Make ready for step (d):
1479 set_req(MemNode::Memory, prev_mem);
1480 return this;
1481 }
1482 }
1483
1484 return NULL; // No further progress
1485 }
1486
1487 // Helper to recognize certain Klass fields which are invariant across
1488 // some group of array types (e.g., int[] or all T[] where T < Object).
1489 const Type*
1490 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1491 ciKlass* klass) const {
1492 if (tkls->offset() == in_bytes(Klass::modifier_flags_offset())) {
1493 // The field is Klass::_modifier_flags. Return its (constant) value.
1494 // (Folds up the 2nd indirection in aClassConstant.getModifiers().)
1495 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags");
1496 return TypeInt::make(klass->modifier_flags());
1497 }
1498 if (tkls->offset() == in_bytes(Klass::access_flags_offset())) {
1499 // The field is Klass::_access_flags. Return its (constant) value.
1500 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1501 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags");
1502 return TypeInt::make(klass->access_flags());
1503 }
1504 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) {
1505 // The field is Klass::_layout_helper. Return its constant value if known.
1506 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper");
1507 return TypeInt::make(klass->layout_helper());
1508 }
1509
1510 // No match.
1511 return NULL;
1512 }
1513
1514 //------------------------------Value-----------------------------------------
1515 const Type *LoadNode::Value( PhaseTransform *phase ) const {
1516 // Either input is TOP ==> the result is TOP
1517 Node* mem = in(MemNode::Memory);
1518 const Type *t1 = phase->type(mem);
1519 if (t1 == Type::TOP) return Type::TOP;
1520 Node* adr = in(MemNode::Address);
1521 const TypePtr* tp = phase->type(adr)->isa_ptr();
1522 if (tp == NULL || tp->empty()) return Type::TOP;
1523 int off = tp->offset();
1524 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
1525 Compile* C = phase->C;
1526
1527 // Try to guess loaded type from pointer type
1528 if (tp->base() == Type::AryPtr) {
1529 const Type *t = tp->is_aryptr()->elem();
1530 // Don't do this for integer types. There is only potential profit if
1531 // the element type t is lower than _type; that is, for int types, if _type is
1532 // more restrictive than t. This only happens here if one is short and the other
1533 // char (both 16 bits), and in those cases we've made an intentional decision
1534 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
1535 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
1536 //
1537 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
1538 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
1539 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
1540 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
1541 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
1542 // In fact, that could have been the original type of p1, and p1 could have
1543 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
1544 // expression (LShiftL quux 3) independently optimized to the constant 8.
1545 if ((t->isa_int() == NULL) && (t->isa_long() == NULL)
1546 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
1547 // t might actually be lower than _type, if _type is a unique
1548 // concrete subclass of abstract class t.
1549 // Make sure the reference is not into the header, by comparing
1550 // the offset against the offset of the start of the array's data.
1551 // Different array types begin at slightly different offsets (12 vs. 16).
1552 // We choose T_BYTE as an example base type that is least restrictive
1553 // as to alignment, which will therefore produce the smallest
1554 // possible base offset.
1555 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
1556 if ((uint)off >= (uint)min_base_off) { // is the offset beyond the header?
1557 const Type* jt = t->join(_type);
1558 // In any case, do not allow the join, per se, to empty out the type.
1559 if (jt->empty() && !t->empty()) {
1560 // This can happen if a interface-typed array narrows to a class type.
1561 jt = _type;
1562 }
1563
1564 if (EliminateAutoBox && adr->is_AddP()) {
1565 // The pointers in the autobox arrays are always non-null
1566 Node* base = adr->in(AddPNode::Base);
1567 if (base != NULL &&
1568 !phase->type(base)->higher_equal(TypePtr::NULL_PTR)) {
1569 Compile::AliasType* atp = C->alias_type(base->adr_type());
1570 if (is_autobox_cache(atp)) {
1571 return jt->join(TypePtr::NOTNULL)->is_ptr();
1572 }
1573 }
1574 }
1575 return jt;
1576 }
1577 }
1578 } else if (tp->base() == Type::InstPtr) {
1579 ciEnv* env = C->env();
1580 const TypeInstPtr* tinst = tp->is_instptr();
1581 ciKlass* klass = tinst->klass();
1582 assert( off != Type::OffsetBot ||
1583 // arrays can be cast to Objects
1584 tp->is_oopptr()->klass()->is_java_lang_Object() ||
1585 // unsafe field access may not have a constant offset
1586 C->has_unsafe_access(),
1587 "Field accesses must be precise" );
1588 // For oop loads, we expect the _type to be precise
1589 if (klass == env->String_klass() &&
1590 adr->is_AddP() && off != Type::OffsetBot) {
1591 // For constant Strings treat the final fields as compile time constants.
1592 Node* base = adr->in(AddPNode::Base);
1593 const TypeOopPtr* t = phase->type(base)->isa_oopptr();
1594 if (t != NULL && t->singleton()) {
1595 ciField* field = env->String_klass()->get_field_by_offset(off, false);
1596 if (field != NULL && field->is_final()) {
1597 ciObject* string = t->const_oop();
1598 ciConstant constant = string->as_instance()->field_value(field);
1599 if (constant.basic_type() == T_INT) {
1600 return TypeInt::make(constant.as_int());
1601 } else if (constant.basic_type() == T_ARRAY) {
1602 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
1603 return TypeNarrowOop::make_from_constant(constant.as_object(), true);
1604 } else {
1605 return TypeOopPtr::make_from_constant(constant.as_object(), true);
1606 }
1607 }
1608 }
1609 }
1610 }
1611 // Optimizations for constant objects
1612 ciObject* const_oop = tinst->const_oop();
1613 if (const_oop != NULL) {
1614 // For constant CallSites treat the target field as a compile time constant.
1615 if (const_oop->is_call_site()) {
1616 ciCallSite* call_site = const_oop->as_call_site();
1617 ciField* field = call_site->klass()->as_instance_klass()->get_field_by_offset(off, /*is_static=*/ false);
1618 if (field != NULL && field->is_call_site_target()) {
1619 ciMethodHandle* target = call_site->get_target();
1620 if (target != NULL) { // just in case
1621 ciConstant constant(T_OBJECT, target);
1622 const Type* t;
1623 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
1624 t = TypeNarrowOop::make_from_constant(constant.as_object(), true);
1625 } else {
1626 t = TypeOopPtr::make_from_constant(constant.as_object(), true);
1627 }
1628 // Add a dependence for invalidation of the optimization.
1629 if (!call_site->is_constant_call_site()) {
1630 C->dependencies()->assert_call_site_target_value(call_site, target);
1631 }
1632 return t;
1633 }
1634 }
1635 }
1636 }
1637 } else if (tp->base() == Type::KlassPtr) {
1638 assert( off != Type::OffsetBot ||
1639 // arrays can be cast to Objects
1640 tp->is_klassptr()->klass()->is_java_lang_Object() ||
1641 // also allow array-loading from the primary supertype
1642 // array during subtype checks
1643 Opcode() == Op_LoadKlass,
1644 "Field accesses must be precise" );
1645 // For klass/static loads, we expect the _type to be precise
1646 }
1647
1648 const TypeKlassPtr *tkls = tp->isa_klassptr();
1649 if (tkls != NULL && !StressReflectiveCode) {
1650 ciKlass* klass = tkls->klass();
1651 if (klass->is_loaded() && tkls->klass_is_exact()) {
1652 // We are loading a field from a Klass metaobject whose identity
1653 // is known at compile time (the type is "exact" or "precise").
1654 // Check for fields we know are maintained as constants by the VM.
1655 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) {
1656 // The field is Klass::_super_check_offset. Return its (constant) value.
1657 // (Folds up type checking code.)
1658 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
1659 return TypeInt::make(klass->super_check_offset());
1660 }
1661 // Compute index into primary_supers array
1662 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(klassOop);
1663 // Check for overflowing; use unsigned compare to handle the negative case.
1664 if( depth < ciKlass::primary_super_limit() ) {
1665 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1666 // (Folds up type checking code.)
1667 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1668 ciKlass *ss = klass->super_of_depth(depth);
1669 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1670 }
1671 const Type* aift = load_array_final_field(tkls, klass);
1672 if (aift != NULL) return aift;
1673 if (tkls->offset() == in_bytes(arrayKlass::component_mirror_offset())
1674 && klass->is_array_klass()) {
1675 // The field is arrayKlass::_component_mirror. Return its (constant) value.
1676 // (Folds up aClassConstant.getComponentType, common in Arrays.copyOf.)
1677 assert(Opcode() == Op_LoadP, "must load an oop from _component_mirror");
1678 return TypeInstPtr::make(klass->as_array_klass()->component_mirror());
1679 }
1680 if (tkls->offset() == in_bytes(Klass::java_mirror_offset())) {
1681 // The field is Klass::_java_mirror. Return its (constant) value.
1682 // (Folds up the 2nd indirection in anObjConstant.getClass().)
1683 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
1684 return TypeInstPtr::make(klass->java_mirror());
1685 }
1686 }
1687
1688 // We can still check if we are loading from the primary_supers array at a
1689 // shallow enough depth. Even though the klass is not exact, entries less
1690 // than or equal to its super depth are correct.
1691 if (klass->is_loaded() ) {
1692 ciType *inner = klass->klass();
1693 while( inner->is_obj_array_klass() )
1694 inner = inner->as_obj_array_klass()->base_element_type();
1695 if( inner->is_instance_klass() &&
1696 !inner->as_instance_klass()->flags().is_interface() ) {
1697 // Compute index into primary_supers array
1698 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(klassOop);
1699 // Check for overflowing; use unsigned compare to handle the negative case.
1700 if( depth < ciKlass::primary_super_limit() &&
1701 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case
1702 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1703 // (Folds up type checking code.)
1704 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1705 ciKlass *ss = klass->super_of_depth(depth);
1706 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1707 }
1708 }
1709 }
1710
1711 // If the type is enough to determine that the thing is not an array,
1712 // we can give the layout_helper a positive interval type.
1713 // This will help short-circuit some reflective code.
1714 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())
1715 && !klass->is_array_klass() // not directly typed as an array
1716 && !klass->is_interface() // specifically not Serializable & Cloneable
1717 && !klass->is_java_lang_Object() // not the supertype of all T[]
1718 ) {
1719 // Note: When interfaces are reliable, we can narrow the interface
1720 // test to (klass != Serializable && klass != Cloneable).
1721 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
1722 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
1723 // The key property of this type is that it folds up tests
1724 // for array-ness, since it proves that the layout_helper is positive.
1725 // Thus, a generic value like the basic object layout helper works fine.
1726 return TypeInt::make(min_size, max_jint, Type::WidenMin);
1727 }
1728 }
1729
1730 // If we are loading from a freshly-allocated object, produce a zero,
1731 // if the load is provably beyond the header of the object.
1732 // (Also allow a variable load from a fresh array to produce zero.)
1733 const TypeOopPtr *tinst = tp->isa_oopptr();
1734 bool is_instance = (tinst != NULL) && tinst->is_known_instance_field();
1735 if (ReduceFieldZeroing || is_instance) {
1736 Node* value = can_see_stored_value(mem,phase);
1737 if (value != NULL && value->is_Con()) {
1738 assert(value->bottom_type()->higher_equal(_type),"sanity");
1739 return value->bottom_type();
1740 }
1741 }
1742
1743 if (is_instance) {
1744 // If we have an instance type and our memory input is the
1745 // programs's initial memory state, there is no matching store,
1746 // so just return a zero of the appropriate type
1747 Node *mem = in(MemNode::Memory);
1748 if (mem->is_Parm() && mem->in(0)->is_Start()) {
1749 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
1750 return Type::get_zero_type(_type->basic_type());
1751 }
1752 }
1753 return _type;
1754 }
1755
1756 //------------------------------match_edge-------------------------------------
1757 // Do we Match on this edge index or not? Match only the address.
1758 uint LoadNode::match_edge(uint idx) const {
1759 return idx == MemNode::Address;
1760 }
1761
1762 //--------------------------LoadBNode::Ideal--------------------------------------
1763 //
1764 // If the previous store is to the same address as this load,
1765 // and the value stored was larger than a byte, replace this load
1766 // with the value stored truncated to a byte. If no truncation is
1767 // needed, the replacement is done in LoadNode::Identity().
1768 //
1769 Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1770 Node* mem = in(MemNode::Memory);
1771 Node* value = can_see_stored_value(mem,phase);
1772 if( value && !phase->type(value)->higher_equal( _type ) ) {
1773 Node *result = phase->transform( new (phase->C) LShiftINode(value, phase->intcon(24)) );
1774 return new (phase->C) RShiftINode(result, phase->intcon(24));
1775 }
1776 // Identity call will handle the case where truncation is not needed.
1777 return LoadNode::Ideal(phase, can_reshape);
1778 }
1779
1780 const Type* LoadBNode::Value(PhaseTransform *phase) const {
1781 Node* mem = in(MemNode::Memory);
1782 Node* value = can_see_stored_value(mem,phase);
1783 if (value != NULL && value->is_Con() &&
1784 !value->bottom_type()->higher_equal(_type)) {
1785 // If the input to the store does not fit with the load's result type,
1786 // it must be truncated. We can't delay until Ideal call since
1787 // a singleton Value is needed for split_thru_phi optimization.
1788 int con = value->get_int();
1789 return TypeInt::make((con << 24) >> 24);
1790 }
1791 return LoadNode::Value(phase);
1792 }
1793
1794 //--------------------------LoadUBNode::Ideal-------------------------------------
1795 //
1796 // If the previous store is to the same address as this load,
1797 // and the value stored was larger than a byte, replace this load
1798 // with the value stored truncated to a byte. If no truncation is
1799 // needed, the replacement is done in LoadNode::Identity().
1800 //
1801 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
1802 Node* mem = in(MemNode::Memory);
1803 Node* value = can_see_stored_value(mem, phase);
1804 if (value && !phase->type(value)->higher_equal(_type))
1805 return new (phase->C) AndINode(value, phase->intcon(0xFF));
1806 // Identity call will handle the case where truncation is not needed.
1807 return LoadNode::Ideal(phase, can_reshape);
1808 }
1809
1810 const Type* LoadUBNode::Value(PhaseTransform *phase) const {
1811 Node* mem = in(MemNode::Memory);
1812 Node* value = can_see_stored_value(mem,phase);
1813 if (value != NULL && value->is_Con() &&
1814 !value->bottom_type()->higher_equal(_type)) {
1815 // If the input to the store does not fit with the load's result type,
1816 // it must be truncated. We can't delay until Ideal call since
1817 // a singleton Value is needed for split_thru_phi optimization.
1818 int con = value->get_int();
1819 return TypeInt::make(con & 0xFF);
1820 }
1821 return LoadNode::Value(phase);
1822 }
1823
1824 //--------------------------LoadUSNode::Ideal-------------------------------------
1825 //
1826 // If the previous store is to the same address as this load,
1827 // and the value stored was larger than a char, replace this load
1828 // with the value stored truncated to a char. If no truncation is
1829 // needed, the replacement is done in LoadNode::Identity().
1830 //
1831 Node *LoadUSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1832 Node* mem = in(MemNode::Memory);
1833 Node* value = can_see_stored_value(mem,phase);
1834 if( value && !phase->type(value)->higher_equal( _type ) )
1835 return new (phase->C) AndINode(value,phase->intcon(0xFFFF));
1836 // Identity call will handle the case where truncation is not needed.
1837 return LoadNode::Ideal(phase, can_reshape);
1838 }
1839
1840 const Type* LoadUSNode::Value(PhaseTransform *phase) const {
1841 Node* mem = in(MemNode::Memory);
1842 Node* value = can_see_stored_value(mem,phase);
1843 if (value != NULL && value->is_Con() &&
1844 !value->bottom_type()->higher_equal(_type)) {
1845 // If the input to the store does not fit with the load's result type,
1846 // it must be truncated. We can't delay until Ideal call since
1847 // a singleton Value is needed for split_thru_phi optimization.
1848 int con = value->get_int();
1849 return TypeInt::make(con & 0xFFFF);
1850 }
1851 return LoadNode::Value(phase);
1852 }
1853
1854 //--------------------------LoadSNode::Ideal--------------------------------------
1855 //
1856 // If the previous store is to the same address as this load,
1857 // and the value stored was larger than a short, replace this load
1858 // with the value stored truncated to a short. If no truncation is
1859 // needed, the replacement is done in LoadNode::Identity().
1860 //
1861 Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1862 Node* mem = in(MemNode::Memory);
1863 Node* value = can_see_stored_value(mem,phase);
1864 if( value && !phase->type(value)->higher_equal( _type ) ) {
1865 Node *result = phase->transform( new (phase->C) LShiftINode(value, phase->intcon(16)) );
1866 return new (phase->C) RShiftINode(result, phase->intcon(16));
1867 }
1868 // Identity call will handle the case where truncation is not needed.
1869 return LoadNode::Ideal(phase, can_reshape);
1870 }
1871
1872 const Type* LoadSNode::Value(PhaseTransform *phase) const {
1873 Node* mem = in(MemNode::Memory);
1874 Node* value = can_see_stored_value(mem,phase);
1875 if (value != NULL && value->is_Con() &&
1876 !value->bottom_type()->higher_equal(_type)) {
1877 // If the input to the store does not fit with the load's result type,
1878 // it must be truncated. We can't delay until Ideal call since
1879 // a singleton Value is needed for split_thru_phi optimization.
1880 int con = value->get_int();
1881 return TypeInt::make((con << 16) >> 16);
1882 }
1883 return LoadNode::Value(phase);
1884 }
1885
1886 //=============================================================================
1887 //----------------------------LoadKlassNode::make------------------------------
1888 // Polymorphic factory method:
1889 Node *LoadKlassNode::make( PhaseGVN& gvn, Node *mem, Node *adr, const TypePtr* at, const TypeKlassPtr *tk ) {
1890 Compile* C = gvn.C;
1891 Node *ctl = NULL;
1892 // sanity check the alias category against the created node type
1893 const TypeOopPtr *adr_type = adr->bottom_type()->isa_oopptr();
1894 assert(adr_type != NULL, "expecting TypeOopPtr");
1895 #ifdef _LP64
1896 if (adr_type->is_ptr_to_narrowoop()) {
1897 Node* load_klass = gvn.transform(new (C) LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowoop()));
1898 return new (C) DecodeNNode(load_klass, load_klass->bottom_type()->make_ptr());
1899 }
1900 #endif
1901 assert(!adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
1902 return new (C) LoadKlassNode(ctl, mem, adr, at, tk);
1903 }
1904
1905 //------------------------------Value------------------------------------------
1906 const Type *LoadKlassNode::Value( PhaseTransform *phase ) const {
1907 return klass_value_common(phase);
1908 }
1909
1910 const Type *LoadNode::klass_value_common( PhaseTransform *phase ) const {
1911 // Either input is TOP ==> the result is TOP
1912 const Type *t1 = phase->type( in(MemNode::Memory) );
1913 if (t1 == Type::TOP) return Type::TOP;
1914 Node *adr = in(MemNode::Address);
1915 const Type *t2 = phase->type( adr );
1916 if (t2 == Type::TOP) return Type::TOP;
1917 const TypePtr *tp = t2->is_ptr();
1918 if (TypePtr::above_centerline(tp->ptr()) ||
1919 tp->ptr() == TypePtr::Null) return Type::TOP;
1920
1921 // Return a more precise klass, if possible
1922 const TypeInstPtr *tinst = tp->isa_instptr();
1923 if (tinst != NULL) {
1924 ciInstanceKlass* ik = tinst->klass()->as_instance_klass();
1925 int offset = tinst->offset();
1926 if (ik == phase->C->env()->Class_klass()
1927 && (offset == java_lang_Class::klass_offset_in_bytes() ||
1928 offset == java_lang_Class::array_klass_offset_in_bytes())) {
1929 // We are loading a special hidden field from a Class mirror object,
1930 // the field which points to the VM's Klass metaobject.
1931 ciType* t = tinst->java_mirror_type();
1932 // java_mirror_type returns non-null for compile-time Class constants.
1933 if (t != NULL) {
1934 // constant oop => constant klass
1935 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
1936 return TypeKlassPtr::make(ciArrayKlass::make(t));
1937 }
1938 if (!t->is_klass()) {
1939 // a primitive Class (e.g., int.class) has NULL for a klass field
1940 return TypePtr::NULL_PTR;
1941 }
1942 // (Folds up the 1st indirection in aClassConstant.getModifiers().)
1943 return TypeKlassPtr::make(t->as_klass());
1944 }
1945 // non-constant mirror, so we can't tell what's going on
1946 }
1947 if( !ik->is_loaded() )
1948 return _type; // Bail out if not loaded
1949 if (offset == oopDesc::klass_offset_in_bytes()) {
1950 if (tinst->klass_is_exact()) {
1951 return TypeKlassPtr::make(ik);
1952 }
1953 // See if we can become precise: no subklasses and no interface
1954 // (Note: We need to support verified interfaces.)
1955 if (!ik->is_interface() && !ik->has_subklass()) {
1956 //assert(!UseExactTypes, "this code should be useless with exact types");
1957 // Add a dependence; if any subclass added we need to recompile
1958 if (!ik->is_final()) {
1959 // %%% should use stronger assert_unique_concrete_subtype instead
1960 phase->C->dependencies()->assert_leaf_type(ik);
1961 }
1962 // Return precise klass
1963 return TypeKlassPtr::make(ik);
1964 }
1965
1966 // Return root of possible klass
1967 return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/);
1968 }
1969 }
1970
1971 // Check for loading klass from an array
1972 const TypeAryPtr *tary = tp->isa_aryptr();
1973 if( tary != NULL ) {
1974 ciKlass *tary_klass = tary->klass();
1975 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP
1976 && tary->offset() == oopDesc::klass_offset_in_bytes()) {
1977 if (tary->klass_is_exact()) {
1978 return TypeKlassPtr::make(tary_klass);
1979 }
1980 ciArrayKlass *ak = tary->klass()->as_array_klass();
1981 // If the klass is an object array, we defer the question to the
1982 // array component klass.
1983 if( ak->is_obj_array_klass() ) {
1984 assert( ak->is_loaded(), "" );
1985 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass();
1986 if( base_k->is_loaded() && base_k->is_instance_klass() ) {
1987 ciInstanceKlass* ik = base_k->as_instance_klass();
1988 // See if we can become precise: no subklasses and no interface
1989 if (!ik->is_interface() && !ik->has_subklass()) {
1990 //assert(!UseExactTypes, "this code should be useless with exact types");
1991 // Add a dependence; if any subclass added we need to recompile
1992 if (!ik->is_final()) {
1993 phase->C->dependencies()->assert_leaf_type(ik);
1994 }
1995 // Return precise array klass
1996 return TypeKlassPtr::make(ak);
1997 }
1998 }
1999 return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/);
2000 } else { // Found a type-array?
2001 //assert(!UseExactTypes, "this code should be useless with exact types");
2002 assert( ak->is_type_array_klass(), "" );
2003 return TypeKlassPtr::make(ak); // These are always precise
2004 }
2005 }
2006 }
2007
2008 // Check for loading klass from an array klass
2009 const TypeKlassPtr *tkls = tp->isa_klassptr();
2010 if (tkls != NULL && !StressReflectiveCode) {
2011 ciKlass* klass = tkls->klass();
2012 if( !klass->is_loaded() )
2013 return _type; // Bail out if not loaded
2014 if( klass->is_obj_array_klass() &&
2015 tkls->offset() == in_bytes(objArrayKlass::element_klass_offset())) {
2016 ciKlass* elem = klass->as_obj_array_klass()->element_klass();
2017 // // Always returning precise element type is incorrect,
2018 // // e.g., element type could be object and array may contain strings
2019 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
2020
2021 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
2022 // according to the element type's subclassing.
2023 return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/);
2024 }
2025 if( klass->is_instance_klass() && tkls->klass_is_exact() &&
2026 tkls->offset() == in_bytes(Klass::super_offset())) {
2027 ciKlass* sup = klass->as_instance_klass()->super();
2028 // The field is Klass::_super. Return its (constant) value.
2029 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
2030 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR;
2031 }
2032 }
2033
2034 // Bailout case
2035 return LoadNode::Value(phase);
2036 }
2037
2038 //------------------------------Identity---------------------------------------
2039 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
2040 // Also feed through the klass in Allocate(...klass...)._klass.
2041 Node* LoadKlassNode::Identity( PhaseTransform *phase ) {
2042 return klass_identity_common(phase);
2043 }
2044
2045 Node* LoadNode::klass_identity_common(PhaseTransform *phase ) {
2046 Node* x = LoadNode::Identity(phase);
2047 if (x != this) return x;
2048
2049 // Take apart the address into an oop and and offset.
2050 // Return 'this' if we cannot.
2051 Node* adr = in(MemNode::Address);
2052 intptr_t offset = 0;
2053 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2054 if (base == NULL) return this;
2055 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
2056 if (toop == NULL) return this;
2057
2058 // We can fetch the klass directly through an AllocateNode.
2059 // This works even if the klass is not constant (clone or newArray).
2060 if (offset == oopDesc::klass_offset_in_bytes()) {
2061 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
2062 if (allocated_klass != NULL) {
2063 return allocated_klass;
2064 }
2065 }
2066
2067 // Simplify k.java_mirror.as_klass to plain k, where k is a klassOop.
2068 // Simplify ak.component_mirror.array_klass to plain ak, ak an arrayKlass.
2069 // See inline_native_Class_query for occurrences of these patterns.
2070 // Java Example: x.getClass().isAssignableFrom(y)
2071 // Java Example: Array.newInstance(x.getClass().getComponentType(), n)
2072 //
2073 // This improves reflective code, often making the Class
2074 // mirror go completely dead. (Current exception: Class
2075 // mirrors may appear in debug info, but we could clean them out by
2076 // introducing a new debug info operator for klassOop.java_mirror).
2077 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass()
2078 && (offset == java_lang_Class::klass_offset_in_bytes() ||
2079 offset == java_lang_Class::array_klass_offset_in_bytes())) {
2080 // We are loading a special hidden field from a Class mirror,
2081 // the field which points to its Klass or arrayKlass metaobject.
2082 if (base->is_Load()) {
2083 Node* adr2 = base->in(MemNode::Address);
2084 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2085 if (tkls != NULL && !tkls->empty()
2086 && (tkls->klass()->is_instance_klass() ||
2087 tkls->klass()->is_array_klass())
2088 && adr2->is_AddP()
2089 ) {
2090 int mirror_field = in_bytes(Klass::java_mirror_offset());
2091 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
2092 mirror_field = in_bytes(arrayKlass::component_mirror_offset());
2093 }
2094 if (tkls->offset() == mirror_field) {
2095 return adr2->in(AddPNode::Base);
2096 }
2097 }
2098 }
2099 }
2100
2101 return this;
2102 }
2103
2104
2105 //------------------------------Value------------------------------------------
2106 const Type *LoadNKlassNode::Value( PhaseTransform *phase ) const {
2107 const Type *t = klass_value_common(phase);
2108 if (t == Type::TOP)
2109 return t;
2110
2111 return t->make_narrowoop();
2112 }
2113
2114 //------------------------------Identity---------------------------------------
2115 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
2116 // Also feed through the klass in Allocate(...klass...)._klass.
2117 Node* LoadNKlassNode::Identity( PhaseTransform *phase ) {
2118 Node *x = klass_identity_common(phase);
2119
2120 const Type *t = phase->type( x );
2121 if( t == Type::TOP ) return x;
2122 if( t->isa_narrowoop()) return x;
2123
2124 return phase->transform(new (phase->C) EncodePNode(x, t->make_narrowoop()));
2125 }
2126
2127 //------------------------------Value-----------------------------------------
2128 const Type *LoadRangeNode::Value( PhaseTransform *phase ) const {
2129 // Either input is TOP ==> the result is TOP
2130 const Type *t1 = phase->type( in(MemNode::Memory) );
2131 if( t1 == Type::TOP ) return Type::TOP;
2132 Node *adr = in(MemNode::Address);
2133 const Type *t2 = phase->type( adr );
2134 if( t2 == Type::TOP ) return Type::TOP;
2135 const TypePtr *tp = t2->is_ptr();
2136 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
2137 const TypeAryPtr *tap = tp->isa_aryptr();
2138 if( !tap ) return _type;
2139 return tap->size();
2140 }
2141
2142 //-------------------------------Ideal---------------------------------------
2143 // Feed through the length in AllocateArray(...length...)._length.
2144 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2145 Node* p = MemNode::Ideal_common(phase, can_reshape);
2146 if (p) return (p == NodeSentinel) ? NULL : p;
2147
2148 // Take apart the address into an oop and and offset.
2149 // Return 'this' if we cannot.
2150 Node* adr = in(MemNode::Address);
2151 intptr_t offset = 0;
2152 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2153 if (base == NULL) return NULL;
2154 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2155 if (tary == NULL) return NULL;
2156
2157 // We can fetch the length directly through an AllocateArrayNode.
2158 // This works even if the length is not constant (clone or newArray).
2159 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2160 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2161 if (alloc != NULL) {
2162 Node* allocated_length = alloc->Ideal_length();
2163 Node* len = alloc->make_ideal_length(tary, phase);
2164 if (allocated_length != len) {
2165 // New CastII improves on this.
2166 return len;
2167 }
2168 }
2169 }
2170
2171 return NULL;
2172 }
2173
2174 //------------------------------Identity---------------------------------------
2175 // Feed through the length in AllocateArray(...length...)._length.
2176 Node* LoadRangeNode::Identity( PhaseTransform *phase ) {
2177 Node* x = LoadINode::Identity(phase);
2178 if (x != this) return x;
2179
2180 // Take apart the address into an oop and and offset.
2181 // Return 'this' if we cannot.
2182 Node* adr = in(MemNode::Address);
2183 intptr_t offset = 0;
2184 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2185 if (base == NULL) return this;
2186 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2187 if (tary == NULL) return this;
2188
2189 // We can fetch the length directly through an AllocateArrayNode.
2190 // This works even if the length is not constant (clone or newArray).
2191 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2192 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2193 if (alloc != NULL) {
2194 Node* allocated_length = alloc->Ideal_length();
2195 // Do not allow make_ideal_length to allocate a CastII node.
2196 Node* len = alloc->make_ideal_length(tary, phase, false);
2197 if (allocated_length == len) {
2198 // Return allocated_length only if it would not be improved by a CastII.
2199 return allocated_length;
2200 }
2201 }
2202 }
2203
2204 return this;
2205
2206 }
2207
2208 //=============================================================================
2209 //---------------------------StoreNode::make-----------------------------------
2210 // Polymorphic factory method:
2211 StoreNode* StoreNode::make( PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt ) {
2212 Compile* C = gvn.C;
2213 assert( C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2214 ctl != NULL, "raw memory operations should have control edge");
2215
2216 switch (bt) {
2217 case T_BOOLEAN: val = gvn.transform(new (C) AndINode(val, gvn.intcon(0x1))); // Fall through to T_BYTE case
2218 case T_BYTE: return new (C) StoreBNode(ctl, mem, adr, adr_type, val);
2219 case T_INT: return new (C) StoreINode(ctl, mem, adr, adr_type, val);
2220 case T_CHAR:
2221 case T_SHORT: return new (C) StoreCNode(ctl, mem, adr, adr_type, val);
2222 case T_LONG: return new (C) StoreLNode(ctl, mem, adr, adr_type, val);
2223 case T_FLOAT: return new (C) StoreFNode(ctl, mem, adr, adr_type, val);
2224 case T_DOUBLE: return new (C) StoreDNode(ctl, mem, adr, adr_type, val);
2225 case T_ADDRESS:
2226 case T_OBJECT:
2227 #ifdef _LP64
2228 if (adr->bottom_type()->is_ptr_to_narrowoop() ||
2229 (UseCompressedOops && val->bottom_type()->isa_klassptr() &&
2230 adr->bottom_type()->isa_rawptr())) {
2231 val = gvn.transform(new (C) EncodePNode(val, val->bottom_type()->make_narrowoop()));
2232 return new (C) StoreNNode(ctl, mem, adr, adr_type, val);
2233 } else
2234 #endif
2235 {
2236 return new (C) StorePNode(ctl, mem, adr, adr_type, val);
2237 }
2238 }
2239 ShouldNotReachHere();
2240 return (StoreNode*)NULL;
2241 }
2242
2243 StoreLNode* StoreLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val) {
2244 bool require_atomic = true;
2245 return new (C) StoreLNode(ctl, mem, adr, adr_type, val, require_atomic);
2246 }
2247
2248
2249 //--------------------------bottom_type----------------------------------------
2250 const Type *StoreNode::bottom_type() const {
2251 return Type::MEMORY;
2252 }
2253
2254 //------------------------------hash-------------------------------------------
2255 uint StoreNode::hash() const {
2256 // unroll addition of interesting fields
2257 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2258
2259 // Since they are not commoned, do not hash them:
2260 return NO_HASH;
2261 }
2262
2263 //------------------------------Ideal------------------------------------------
2264 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
2265 // When a store immediately follows a relevant allocation/initialization,
2266 // try to capture it into the initialization, or hoist it above.
2267 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2268 Node* p = MemNode::Ideal_common(phase, can_reshape);
2269 if (p) return (p == NodeSentinel) ? NULL : p;
2270
2271 Node* mem = in(MemNode::Memory);
2272 Node* address = in(MemNode::Address);
2273
2274 // Back-to-back stores to same address? Fold em up. Generally
2275 // unsafe if I have intervening uses... Also disallowed for StoreCM
2276 // since they must follow each StoreP operation. Redundant StoreCMs
2277 // are eliminated just before matching in final_graph_reshape.
2278 if (mem->is_Store() && mem->in(MemNode::Address)->eqv_uncast(address) &&
2279 mem->Opcode() != Op_StoreCM) {
2280 // Looking at a dead closed cycle of memory?
2281 assert(mem != mem->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
2282
2283 assert(Opcode() == mem->Opcode() ||
2284 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw,
2285 "no mismatched stores, except on raw memory");
2286
2287 if (mem->outcnt() == 1 && // check for intervening uses
2288 mem->as_Store()->memory_size() <= this->memory_size()) {
2289 // If anybody other than 'this' uses 'mem', we cannot fold 'mem' away.
2290 // For example, 'mem' might be the final state at a conditional return.
2291 // Or, 'mem' might be used by some node which is live at the same time
2292 // 'this' is live, which might be unschedulable. So, require exactly
2293 // ONE user, the 'this' store, until such time as we clone 'mem' for
2294 // each of 'mem's uses (thus making the exactly-1-user-rule hold true).
2295 if (can_reshape) { // (%%% is this an anachronism?)
2296 set_req_X(MemNode::Memory, mem->in(MemNode::Memory),
2297 phase->is_IterGVN());
2298 } else {
2299 // It's OK to do this in the parser, since DU info is always accurate,
2300 // and the parser always refers to nodes via SafePointNode maps.
2301 set_req(MemNode::Memory, mem->in(MemNode::Memory));
2302 }
2303 return this;
2304 }
2305 }
2306
2307 // Capture an unaliased, unconditional, simple store into an initializer.
2308 // Or, if it is independent of the allocation, hoist it above the allocation.
2309 if (ReduceFieldZeroing && /*can_reshape &&*/
2310 mem->is_Proj() && mem->in(0)->is_Initialize()) {
2311 InitializeNode* init = mem->in(0)->as_Initialize();
2312 intptr_t offset = init->can_capture_store(this, phase);
2313 if (offset > 0) {
2314 Node* moved = init->capture_store(this, offset, phase);
2315 // If the InitializeNode captured me, it made a raw copy of me,
2316 // and I need to disappear.
2317 if (moved != NULL) {
2318 // %%% hack to ensure that Ideal returns a new node:
2319 mem = MergeMemNode::make(phase->C, mem);
2320 return mem; // fold me away
2321 }
2322 }
2323 }
2324
2325 return NULL; // No further progress
2326 }
2327
2328 //------------------------------Value-----------------------------------------
2329 const Type *StoreNode::Value( PhaseTransform *phase ) const {
2330 // Either input is TOP ==> the result is TOP
2331 const Type *t1 = phase->type( in(MemNode::Memory) );
2332 if( t1 == Type::TOP ) return Type::TOP;
2333 const Type *t2 = phase->type( in(MemNode::Address) );
2334 if( t2 == Type::TOP ) return Type::TOP;
2335 const Type *t3 = phase->type( in(MemNode::ValueIn) );
2336 if( t3 == Type::TOP ) return Type::TOP;
2337 return Type::MEMORY;
2338 }
2339
2340 //------------------------------Identity---------------------------------------
2341 // Remove redundant stores:
2342 // Store(m, p, Load(m, p)) changes to m.
2343 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
2344 Node *StoreNode::Identity( PhaseTransform *phase ) {
2345 Node* mem = in(MemNode::Memory);
2346 Node* adr = in(MemNode::Address);
2347 Node* val = in(MemNode::ValueIn);
2348
2349 // Load then Store? Then the Store is useless
2350 if (val->is_Load() &&
2351 val->in(MemNode::Address)->eqv_uncast(adr) &&
2352 val->in(MemNode::Memory )->eqv_uncast(mem) &&
2353 val->as_Load()->store_Opcode() == Opcode()) {
2354 return mem;
2355 }
2356
2357 // Two stores in a row of the same value?
2358 if (mem->is_Store() &&
2359 mem->in(MemNode::Address)->eqv_uncast(adr) &&
2360 mem->in(MemNode::ValueIn)->eqv_uncast(val) &&
2361 mem->Opcode() == Opcode()) {
2362 return mem;
2363 }
2364
2365 // Store of zero anywhere into a freshly-allocated object?
2366 // Then the store is useless.
2367 // (It must already have been captured by the InitializeNode.)
2368 if (ReduceFieldZeroing && phase->type(val)->is_zero_type()) {
2369 // a newly allocated object is already all-zeroes everywhere
2370 if (mem->is_Proj() && mem->in(0)->is_Allocate()) {
2371 return mem;
2372 }
2373
2374 // the store may also apply to zero-bits in an earlier object
2375 Node* prev_mem = find_previous_store(phase);
2376 // Steps (a), (b): Walk past independent stores to find an exact match.
2377 if (prev_mem != NULL) {
2378 Node* prev_val = can_see_stored_value(prev_mem, phase);
2379 if (prev_val != NULL && phase->eqv(prev_val, val)) {
2380 // prev_val and val might differ by a cast; it would be good
2381 // to keep the more informative of the two.
2382 return mem;
2383 }
2384 }
2385 }
2386
2387 return this;
2388 }
2389
2390 //------------------------------match_edge-------------------------------------
2391 // Do we Match on this edge index or not? Match only memory & value
2392 uint StoreNode::match_edge(uint idx) const {
2393 return idx == MemNode::Address || idx == MemNode::ValueIn;
2394 }
2395
2396 //------------------------------cmp--------------------------------------------
2397 // Do not common stores up together. They generally have to be split
2398 // back up anyways, so do not bother.
2399 uint StoreNode::cmp( const Node &n ) const {
2400 return (&n == this); // Always fail except on self
2401 }
2402
2403 //------------------------------Ideal_masked_input-----------------------------
2404 // Check for a useless mask before a partial-word store
2405 // (StoreB ... (AndI valIn conIa) )
2406 // If (conIa & mask == mask) this simplifies to
2407 // (StoreB ... (valIn) )
2408 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
2409 Node *val = in(MemNode::ValueIn);
2410 if( val->Opcode() == Op_AndI ) {
2411 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2412 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
2413 set_req(MemNode::ValueIn, val->in(1));
2414 return this;
2415 }
2416 }
2417 return NULL;
2418 }
2419
2420
2421 //------------------------------Ideal_sign_extended_input----------------------
2422 // Check for useless sign-extension before a partial-word store
2423 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) )
2424 // If (conIL == conIR && conIR <= num_bits) this simplifies to
2425 // (StoreB ... (valIn) )
2426 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) {
2427 Node *val = in(MemNode::ValueIn);
2428 if( val->Opcode() == Op_RShiftI ) {
2429 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2430 if( t && t->is_con() && (t->get_con() <= num_bits) ) {
2431 Node *shl = val->in(1);
2432 if( shl->Opcode() == Op_LShiftI ) {
2433 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int();
2434 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) {
2435 set_req(MemNode::ValueIn, shl->in(1));
2436 return this;
2437 }
2438 }
2439 }
2440 }
2441 return NULL;
2442 }
2443
2444 //------------------------------value_never_loaded-----------------------------------
2445 // Determine whether there are any possible loads of the value stored.
2446 // For simplicity, we actually check if there are any loads from the
2447 // address stored to, not just for loads of the value stored by this node.
2448 //
2449 bool StoreNode::value_never_loaded( PhaseTransform *phase) const {
2450 Node *adr = in(Address);
2451 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
2452 if (adr_oop == NULL)
2453 return false;
2454 if (!adr_oop->is_known_instance_field())
2455 return false; // if not a distinct instance, there may be aliases of the address
2456 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
2457 Node *use = adr->fast_out(i);
2458 int opc = use->Opcode();
2459 if (use->is_Load() || use->is_LoadStore()) {
2460 return false;
2461 }
2462 }
2463 return true;
2464 }
2465
2466 //=============================================================================
2467 //------------------------------Ideal------------------------------------------
2468 // If the store is from an AND mask that leaves the low bits untouched, then
2469 // we can skip the AND operation. If the store is from a sign-extension
2470 // (a left shift, then right shift) we can skip both.
2471 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
2472 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
2473 if( progress != NULL ) return progress;
2474
2475 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
2476 if( progress != NULL ) return progress;
2477
2478 // Finally check the default case
2479 return StoreNode::Ideal(phase, can_reshape);
2480 }
2481
2482 //=============================================================================
2483 //------------------------------Ideal------------------------------------------
2484 // If the store is from an AND mask that leaves the low bits untouched, then
2485 // we can skip the AND operation
2486 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
2487 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
2488 if( progress != NULL ) return progress;
2489
2490 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
2491 if( progress != NULL ) return progress;
2492
2493 // Finally check the default case
2494 return StoreNode::Ideal(phase, can_reshape);
2495 }
2496
2497 //=============================================================================
2498 //------------------------------Identity---------------------------------------
2499 Node *StoreCMNode::Identity( PhaseTransform *phase ) {
2500 // No need to card mark when storing a null ptr
2501 Node* my_store = in(MemNode::OopStore);
2502 if (my_store->is_Store()) {
2503 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) );
2504 if( t1 == TypePtr::NULL_PTR ) {
2505 return in(MemNode::Memory);
2506 }
2507 }
2508 return this;
2509 }
2510
2511 //=============================================================================
2512 //------------------------------Ideal---------------------------------------
2513 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){
2514 Node* progress = StoreNode::Ideal(phase, can_reshape);
2515 if (progress != NULL) return progress;
2516
2517 Node* my_store = in(MemNode::OopStore);
2518 if (my_store->is_MergeMem()) {
2519 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx());
2520 set_req(MemNode::OopStore, mem);
2521 return this;
2522 }
2523
2524 return NULL;
2525 }
2526
2527 //------------------------------Value-----------------------------------------
2528 const Type *StoreCMNode::Value( PhaseTransform *phase ) const {
2529 // Either input is TOP ==> the result is TOP
2530 const Type *t = phase->type( in(MemNode::Memory) );
2531 if( t == Type::TOP ) return Type::TOP;
2532 t = phase->type( in(MemNode::Address) );
2533 if( t == Type::TOP ) return Type::TOP;
2534 t = phase->type( in(MemNode::ValueIn) );
2535 if( t == Type::TOP ) return Type::TOP;
2536 // If extra input is TOP ==> the result is TOP
2537 t = phase->type( in(MemNode::OopStore) );
2538 if( t == Type::TOP ) return Type::TOP;
2539
2540 return StoreNode::Value( phase );
2541 }
2542
2543
2544 //=============================================================================
2545 //----------------------------------SCMemProjNode------------------------------
2546 const Type * SCMemProjNode::Value( PhaseTransform *phase ) const
2547 {
2548 return bottom_type();
2549 }
2550
2551 //=============================================================================
2552 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : Node(5) {
2553 init_req(MemNode::Control, c );
2554 init_req(MemNode::Memory , mem);
2555 init_req(MemNode::Address, adr);
2556 init_req(MemNode::ValueIn, val);
2557 init_req( ExpectedIn, ex );
2558 init_class_id(Class_LoadStore);
2559
2560 }
2561
2562 //=============================================================================
2563 //-------------------------------adr_type--------------------------------------
2564 // Do we Match on this edge index or not? Do not match memory
2565 const TypePtr* ClearArrayNode::adr_type() const {
2566 Node *adr = in(3);
2567 return MemNode::calculate_adr_type(adr->bottom_type());
2568 }
2569
2570 //------------------------------match_edge-------------------------------------
2571 // Do we Match on this edge index or not? Do not match memory
2572 uint ClearArrayNode::match_edge(uint idx) const {
2573 return idx > 1;
2574 }
2575
2576 //------------------------------Identity---------------------------------------
2577 // Clearing a zero length array does nothing
2578 Node *ClearArrayNode::Identity( PhaseTransform *phase ) {
2579 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
2580 }
2581
2582 //------------------------------Idealize---------------------------------------
2583 // Clearing a short array is faster with stores
2584 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape){
2585 const int unit = BytesPerLong;
2586 const TypeX* t = phase->type(in(2))->isa_intptr_t();
2587 if (!t) return NULL;
2588 if (!t->is_con()) return NULL;
2589 intptr_t raw_count = t->get_con();
2590 intptr_t size = raw_count;
2591 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
2592 // Clearing nothing uses the Identity call.
2593 // Negative clears are possible on dead ClearArrays
2594 // (see jck test stmt114.stmt11402.val).
2595 if (size <= 0 || size % unit != 0) return NULL;
2596 intptr_t count = size / unit;
2597 // Length too long; use fast hardware clear
2598 if (size > Matcher::init_array_short_size) return NULL;
2599 Node *mem = in(1);
2600 if( phase->type(mem)==Type::TOP ) return NULL;
2601 Node *adr = in(3);
2602 const Type* at = phase->type(adr);
2603 if( at==Type::TOP ) return NULL;
2604 const TypePtr* atp = at->isa_ptr();
2605 // adjust atp to be the correct array element address type
2606 if (atp == NULL) atp = TypePtr::BOTTOM;
2607 else atp = atp->add_offset(Type::OffsetBot);
2608 // Get base for derived pointer purposes
2609 if( adr->Opcode() != Op_AddP ) Unimplemented();
2610 Node *base = adr->in(1);
2611
2612 Node *zero = phase->makecon(TypeLong::ZERO);
2613 Node *off = phase->MakeConX(BytesPerLong);
2614 mem = new (phase->C) StoreLNode(in(0),mem,adr,atp,zero);
2615 count--;
2616 while( count-- ) {
2617 mem = phase->transform(mem);
2618 adr = phase->transform(new (phase->C) AddPNode(base,adr,off));
2619 mem = new (phase->C) StoreLNode(in(0),mem,adr,atp,zero);
2620 }
2621 return mem;
2622 }
2623
2624 //----------------------------step_through----------------------------------
2625 // Return allocation input memory edge if it is different instance
2626 // or itself if it is the one we are looking for.
2627 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) {
2628 Node* n = *np;
2629 assert(n->is_ClearArray(), "sanity");
2630 intptr_t offset;
2631 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
2632 // This method is called only before Allocate nodes are expanded during
2633 // macro nodes expansion. Before that ClearArray nodes are only generated
2634 // in LibraryCallKit::generate_arraycopy() which follows allocations.
2635 assert(alloc != NULL, "should have allocation");
2636 if (alloc->_idx == instance_id) {
2637 // Can not bypass initialization of the instance we are looking for.
2638 return false;
2639 }
2640 // Otherwise skip it.
2641 InitializeNode* init = alloc->initialization();
2642 if (init != NULL)
2643 *np = init->in(TypeFunc::Memory);
2644 else
2645 *np = alloc->in(TypeFunc::Memory);
2646 return true;
2647 }
2648
2649 //----------------------------clear_memory-------------------------------------
2650 // Generate code to initialize object storage to zero.
2651 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2652 intptr_t start_offset,
2653 Node* end_offset,
2654 PhaseGVN* phase) {
2655 Compile* C = phase->C;
2656 intptr_t offset = start_offset;
2657
2658 int unit = BytesPerLong;
2659 if ((offset % unit) != 0) {
2660 Node* adr = new (C) AddPNode(dest, dest, phase->MakeConX(offset));
2661 adr = phase->transform(adr);
2662 const TypePtr* atp = TypeRawPtr::BOTTOM;
2663 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT);
2664 mem = phase->transform(mem);
2665 offset += BytesPerInt;
2666 }
2667 assert((offset % unit) == 0, "");
2668
2669 // Initialize the remaining stuff, if any, with a ClearArray.
2670 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase);
2671 }
2672
2673 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2674 Node* start_offset,
2675 Node* end_offset,
2676 PhaseGVN* phase) {
2677 if (start_offset == end_offset) {
2678 // nothing to do
2679 return mem;
2680 }
2681
2682 Compile* C = phase->C;
2683 int unit = BytesPerLong;
2684 Node* zbase = start_offset;
2685 Node* zend = end_offset;
2686
2687 // Scale to the unit required by the CPU:
2688 if (!Matcher::init_array_count_is_in_bytes) {
2689 Node* shift = phase->intcon(exact_log2(unit));
2690 zbase = phase->transform( new(C) URShiftXNode(zbase, shift) );
2691 zend = phase->transform( new(C) URShiftXNode(zend, shift) );
2692 }
2693
2694 Node* zsize = phase->transform( new(C) SubXNode(zend, zbase) );
2695 Node* zinit = phase->zerocon((unit == BytesPerLong) ? T_LONG : T_INT);
2696
2697 // Bulk clear double-words
2698 Node* adr = phase->transform( new(C) AddPNode(dest, dest, start_offset) );
2699 mem = new (C) ClearArrayNode(ctl, mem, zsize, adr);
2700 return phase->transform(mem);
2701 }
2702
2703 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2704 intptr_t start_offset,
2705 intptr_t end_offset,
2706 PhaseGVN* phase) {
2707 if (start_offset == end_offset) {
2708 // nothing to do
2709 return mem;
2710 }
2711
2712 Compile* C = phase->C;
2713 assert((end_offset % BytesPerInt) == 0, "odd end offset");
2714 intptr_t done_offset = end_offset;
2715 if ((done_offset % BytesPerLong) != 0) {
2716 done_offset -= BytesPerInt;
2717 }
2718 if (done_offset > start_offset) {
2719 mem = clear_memory(ctl, mem, dest,
2720 start_offset, phase->MakeConX(done_offset), phase);
2721 }
2722 if (done_offset < end_offset) { // emit the final 32-bit store
2723 Node* adr = new (C) AddPNode(dest, dest, phase->MakeConX(done_offset));
2724 adr = phase->transform(adr);
2725 const TypePtr* atp = TypeRawPtr::BOTTOM;
2726 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT);
2727 mem = phase->transform(mem);
2728 done_offset += BytesPerInt;
2729 }
2730 assert(done_offset == end_offset, "");
2731 return mem;
2732 }
2733
2734 //=============================================================================
2735 // Do not match memory edge.
2736 uint StrIntrinsicNode::match_edge(uint idx) const {
2737 return idx == 2 || idx == 3;
2738 }
2739
2740 //------------------------------Ideal------------------------------------------
2741 // Return a node which is more "ideal" than the current node. Strip out
2742 // control copies
2743 Node *StrIntrinsicNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2744 if (remove_dead_region(phase, can_reshape)) return this;
2745 // Don't bother trying to transform a dead node
2746 if (in(0) && in(0)->is_top()) return NULL;
2747
2748 if (can_reshape) {
2749 Node* mem = phase->transform(in(MemNode::Memory));
2750 // If transformed to a MergeMem, get the desired slice
2751 uint alias_idx = phase->C->get_alias_index(adr_type());
2752 mem = mem->is_MergeMem() ? mem->as_MergeMem()->memory_at(alias_idx) : mem;
2753 if (mem != in(MemNode::Memory)) {
2754 set_req(MemNode::Memory, mem);
2755 return this;
2756 }
2757 }
2758 return NULL;
2759 }
2760
2761 //------------------------------Value------------------------------------------
2762 const Type *StrIntrinsicNode::Value( PhaseTransform *phase ) const {
2763 if (in(0) && phase->type(in(0)) == Type::TOP) return Type::TOP;
2764 return bottom_type();
2765 }
2766
2767 //=============================================================================
2768 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
2769 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)),
2770 _adr_type(C->get_adr_type(alias_idx))
2771 {
2772 init_class_id(Class_MemBar);
2773 Node* top = C->top();
2774 init_req(TypeFunc::I_O,top);
2775 init_req(TypeFunc::FramePtr,top);
2776 init_req(TypeFunc::ReturnAdr,top);
2777 if (precedent != NULL)
2778 init_req(TypeFunc::Parms, precedent);
2779 }
2780
2781 //------------------------------cmp--------------------------------------------
2782 uint MemBarNode::hash() const { return NO_HASH; }
2783 uint MemBarNode::cmp( const Node &n ) const {
2784 return (&n == this); // Always fail except on self
2785 }
2786
2787 //------------------------------make-------------------------------------------
2788 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
2789 switch (opcode) {
2790 case Op_MemBarAcquire: return new(C) MemBarAcquireNode(C, atp, pn);
2791 case Op_MemBarRelease: return new(C) MemBarReleaseNode(C, atp, pn);
2792 case Op_MemBarAcquireLock: return new(C) MemBarAcquireLockNode(C, atp, pn);
2793 case Op_MemBarReleaseLock: return new(C) MemBarReleaseLockNode(C, atp, pn);
2794 case Op_MemBarVolatile: return new(C) MemBarVolatileNode(C, atp, pn);
2795 case Op_MemBarCPUOrder: return new(C) MemBarCPUOrderNode(C, atp, pn);
2796 case Op_Initialize: return new(C) InitializeNode(C, atp, pn);
2797 case Op_MemBarStoreStore: return new(C) MemBarStoreStoreNode(C, atp, pn);
2798 default: ShouldNotReachHere(); return NULL;
2799 }
2800 }
2801
2802 //------------------------------Ideal------------------------------------------
2803 // Return a node which is more "ideal" than the current node. Strip out
2804 // control copies
2805 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2806 if (remove_dead_region(phase, can_reshape)) return this;
2807 // Don't bother trying to transform a dead node
2808 if (in(0) && in(0)->is_top()) return NULL;
2809
2810 // Eliminate volatile MemBars for scalar replaced objects.
2811 if (can_reshape && req() == (Precedent+1) &&
2812 (Opcode() == Op_MemBarAcquire || Opcode() == Op_MemBarVolatile)) {
2813 // Volatile field loads and stores.
2814 Node* my_mem = in(MemBarNode::Precedent);
2815 if (my_mem != NULL && my_mem->is_Mem()) {
2816 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
2817 // Check for scalar replaced object reference.
2818 if( t_oop != NULL && t_oop->is_known_instance_field() &&
2819 t_oop->offset() != Type::OffsetBot &&
2820 t_oop->offset() != Type::OffsetTop) {
2821 // Replace MemBar projections by its inputs.
2822 PhaseIterGVN* igvn = phase->is_IterGVN();
2823 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
2824 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
2825 // Must return either the original node (now dead) or a new node
2826 // (Do not return a top here, since that would break the uniqueness of top.)
2827 return new (phase->C) ConINode(TypeInt::ZERO);
2828 }
2829 }
2830 }
2831 return NULL;
2832 }
2833
2834 //------------------------------Value------------------------------------------
2835 const Type *MemBarNode::Value( PhaseTransform *phase ) const {
2836 if( !in(0) ) return Type::TOP;
2837 if( phase->type(in(0)) == Type::TOP )
2838 return Type::TOP;
2839 return TypeTuple::MEMBAR;
2840 }
2841
2842 //------------------------------match------------------------------------------
2843 // Construct projections for memory.
2844 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) {
2845 switch (proj->_con) {
2846 case TypeFunc::Control:
2847 case TypeFunc::Memory:
2848 return new (m->C) MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
2849 }
2850 ShouldNotReachHere();
2851 return NULL;
2852 }
2853
2854 //===========================InitializeNode====================================
2855 // SUMMARY:
2856 // This node acts as a memory barrier on raw memory, after some raw stores.
2857 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
2858 // The Initialize can 'capture' suitably constrained stores as raw inits.
2859 // It can coalesce related raw stores into larger units (called 'tiles').
2860 // It can avoid zeroing new storage for memory units which have raw inits.
2861 // At macro-expansion, it is marked 'complete', and does not optimize further.
2862 //
2863 // EXAMPLE:
2864 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
2865 // ctl = incoming control; mem* = incoming memory
2866 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
2867 // First allocate uninitialized memory and fill in the header:
2868 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
2869 // ctl := alloc.Control; mem* := alloc.Memory*
2870 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
2871 // Then initialize to zero the non-header parts of the raw memory block:
2872 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
2873 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
2874 // After the initialize node executes, the object is ready for service:
2875 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
2876 // Suppose its body is immediately initialized as {1,2}:
2877 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
2878 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
2879 // mem.SLICE(#short[*]) := store2
2880 //
2881 // DETAILS:
2882 // An InitializeNode collects and isolates object initialization after
2883 // an AllocateNode and before the next possible safepoint. As a
2884 // memory barrier (MemBarNode), it keeps critical stores from drifting
2885 // down past any safepoint or any publication of the allocation.
2886 // Before this barrier, a newly-allocated object may have uninitialized bits.
2887 // After this barrier, it may be treated as a real oop, and GC is allowed.
2888 //
2889 // The semantics of the InitializeNode include an implicit zeroing of
2890 // the new object from object header to the end of the object.
2891 // (The object header and end are determined by the AllocateNode.)
2892 //
2893 // Certain stores may be added as direct inputs to the InitializeNode.
2894 // These stores must update raw memory, and they must be to addresses
2895 // derived from the raw address produced by AllocateNode, and with
2896 // a constant offset. They must be ordered by increasing offset.
2897 // The first one is at in(RawStores), the last at in(req()-1).
2898 // Unlike most memory operations, they are not linked in a chain,
2899 // but are displayed in parallel as users of the rawmem output of
2900 // the allocation.
2901 //
2902 // (See comments in InitializeNode::capture_store, which continue
2903 // the example given above.)
2904 //
2905 // When the associated Allocate is macro-expanded, the InitializeNode
2906 // may be rewritten to optimize collected stores. A ClearArrayNode
2907 // may also be created at that point to represent any required zeroing.
2908 // The InitializeNode is then marked 'complete', prohibiting further
2909 // capturing of nearby memory operations.
2910 //
2911 // During macro-expansion, all captured initializations which store
2912 // constant values of 32 bits or smaller are coalesced (if advantageous)
2913 // into larger 'tiles' 32 or 64 bits. This allows an object to be
2914 // initialized in fewer memory operations. Memory words which are
2915 // covered by neither tiles nor non-constant stores are pre-zeroed
2916 // by explicit stores of zero. (The code shape happens to do all
2917 // zeroing first, then all other stores, with both sequences occurring
2918 // in order of ascending offsets.)
2919 //
2920 // Alternatively, code may be inserted between an AllocateNode and its
2921 // InitializeNode, to perform arbitrary initialization of the new object.
2922 // E.g., the object copying intrinsics insert complex data transfers here.
2923 // The initialization must then be marked as 'complete' disable the
2924 // built-in zeroing semantics and the collection of initializing stores.
2925 //
2926 // While an InitializeNode is incomplete, reads from the memory state
2927 // produced by it are optimizable if they match the control edge and
2928 // new oop address associated with the allocation/initialization.
2929 // They return a stored value (if the offset matches) or else zero.
2930 // A write to the memory state, if it matches control and address,
2931 // and if it is to a constant offset, may be 'captured' by the
2932 // InitializeNode. It is cloned as a raw memory operation and rewired
2933 // inside the initialization, to the raw oop produced by the allocation.
2934 // Operations on addresses which are provably distinct (e.g., to
2935 // other AllocateNodes) are allowed to bypass the initialization.
2936 //
2937 // The effect of all this is to consolidate object initialization
2938 // (both arrays and non-arrays, both piecewise and bulk) into a
2939 // single location, where it can be optimized as a unit.
2940 //
2941 // Only stores with an offset less than TrackedInitializationLimit words
2942 // will be considered for capture by an InitializeNode. This puts a
2943 // reasonable limit on the complexity of optimized initializations.
2944
2945 //---------------------------InitializeNode------------------------------------
2946 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
2947 : _is_complete(Incomplete), _does_not_escape(false),
2948 MemBarNode(C, adr_type, rawoop)
2949 {
2950 init_class_id(Class_Initialize);
2951
2952 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
2953 assert(in(RawAddress) == rawoop, "proper init");
2954 // Note: allocation() can be NULL, for secondary initialization barriers
2955 }
2956
2957 // Since this node is not matched, it will be processed by the
2958 // register allocator. Declare that there are no constraints
2959 // on the allocation of the RawAddress edge.
2960 const RegMask &InitializeNode::in_RegMask(uint idx) const {
2961 // This edge should be set to top, by the set_complete. But be conservative.
2962 if (idx == InitializeNode::RawAddress)
2963 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
2964 return RegMask::Empty;
2965 }
2966
2967 Node* InitializeNode::memory(uint alias_idx) {
2968 Node* mem = in(Memory);
2969 if (mem->is_MergeMem()) {
2970 return mem->as_MergeMem()->memory_at(alias_idx);
2971 } else {
2972 // incoming raw memory is not split
2973 return mem;
2974 }
2975 }
2976
2977 bool InitializeNode::is_non_zero() {
2978 if (is_complete()) return false;
2979 remove_extra_zeroes();
2980 return (req() > RawStores);
2981 }
2982
2983 void InitializeNode::set_complete(PhaseGVN* phase) {
2984 assert(!is_complete(), "caller responsibility");
2985 _is_complete = Complete;
2986
2987 // After this node is complete, it contains a bunch of
2988 // raw-memory initializations. There is no need for
2989 // it to have anything to do with non-raw memory effects.
2990 // Therefore, tell all non-raw users to re-optimize themselves,
2991 // after skipping the memory effects of this initialization.
2992 PhaseIterGVN* igvn = phase->is_IterGVN();
2993 if (igvn) igvn->add_users_to_worklist(this);
2994 }
2995
2996 // convenience function
2997 // return false if the init contains any stores already
2998 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
2999 InitializeNode* init = initialization();
3000 if (init == NULL || init->is_complete()) return false;
3001 init->remove_extra_zeroes();
3002 // for now, if this allocation has already collected any inits, bail:
3003 if (init->is_non_zero()) return false;
3004 init->set_complete(phase);
3005 return true;
3006 }
3007
3008 void InitializeNode::remove_extra_zeroes() {
3009 if (req() == RawStores) return;
3010 Node* zmem = zero_memory();
3011 uint fill = RawStores;
3012 for (uint i = fill; i < req(); i++) {
3013 Node* n = in(i);
3014 if (n->is_top() || n == zmem) continue; // skip
3015 if (fill < i) set_req(fill, n); // compact
3016 ++fill;
3017 }
3018 // delete any empty spaces created:
3019 while (fill < req()) {
3020 del_req(fill);
3021 }
3022 }
3023
3024 // Helper for remembering which stores go with which offsets.
3025 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) {
3026 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
3027 intptr_t offset = -1;
3028 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
3029 phase, offset);
3030 if (base == NULL) return -1; // something is dead,
3031 if (offset < 0) return -1; // dead, dead
3032 return offset;
3033 }
3034
3035 // Helper for proving that an initialization expression is
3036 // "simple enough" to be folded into an object initialization.
3037 // Attempts to prove that a store's initial value 'n' can be captured
3038 // within the initialization without creating a vicious cycle, such as:
3039 // { Foo p = new Foo(); p.next = p; }
3040 // True for constants and parameters and small combinations thereof.
3041 bool InitializeNode::detect_init_independence(Node* n,
3042 bool st_is_pinned,
3043 int& count) {
3044 if (n == NULL) return true; // (can this really happen?)
3045 if (n->is_Proj()) n = n->in(0);
3046 if (n == this) return false; // found a cycle
3047 if (n->is_Con()) return true;
3048 if (n->is_Start()) return true; // params, etc., are OK
3049 if (n->is_Root()) return true; // even better
3050
3051 Node* ctl = n->in(0);
3052 if (ctl != NULL && !ctl->is_top()) {
3053 if (ctl->is_Proj()) ctl = ctl->in(0);
3054 if (ctl == this) return false;
3055
3056 // If we already know that the enclosing memory op is pinned right after
3057 // the init, then any control flow that the store has picked up
3058 // must have preceded the init, or else be equal to the init.
3059 // Even after loop optimizations (which might change control edges)
3060 // a store is never pinned *before* the availability of its inputs.
3061 if (!MemNode::all_controls_dominate(n, this))
3062 return false; // failed to prove a good control
3063
3064 }
3065
3066 // Check data edges for possible dependencies on 'this'.
3067 if ((count += 1) > 20) return false; // complexity limit
3068 for (uint i = 1; i < n->req(); i++) {
3069 Node* m = n->in(i);
3070 if (m == NULL || m == n || m->is_top()) continue;
3071 uint first_i = n->find_edge(m);
3072 if (i != first_i) continue; // process duplicate edge just once
3073 if (!detect_init_independence(m, st_is_pinned, count)) {
3074 return false;
3075 }
3076 }
3077
3078 return true;
3079 }
3080
3081 // Here are all the checks a Store must pass before it can be moved into
3082 // an initialization. Returns zero if a check fails.
3083 // On success, returns the (constant) offset to which the store applies,
3084 // within the initialized memory.
3085 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase) {
3086 const int FAIL = 0;
3087 if (st->req() != MemNode::ValueIn + 1)
3088 return FAIL; // an inscrutable StoreNode (card mark?)
3089 Node* ctl = st->in(MemNode::Control);
3090 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this))
3091 return FAIL; // must be unconditional after the initialization
3092 Node* mem = st->in(MemNode::Memory);
3093 if (!(mem->is_Proj() && mem->in(0) == this))
3094 return FAIL; // must not be preceded by other stores
3095 Node* adr = st->in(MemNode::Address);
3096 intptr_t offset;
3097 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
3098 if (alloc == NULL)
3099 return FAIL; // inscrutable address
3100 if (alloc != allocation())
3101 return FAIL; // wrong allocation! (store needs to float up)
3102 Node* val = st->in(MemNode::ValueIn);
3103 int complexity_count = 0;
3104 if (!detect_init_independence(val, true, complexity_count))
3105 return FAIL; // stored value must be 'simple enough'
3106
3107 return offset; // success
3108 }
3109
3110 // Find the captured store in(i) which corresponds to the range
3111 // [start..start+size) in the initialized object.
3112 // If there is one, return its index i. If there isn't, return the
3113 // negative of the index where it should be inserted.
3114 // Return 0 if the queried range overlaps an initialization boundary
3115 // or if dead code is encountered.
3116 // If size_in_bytes is zero, do not bother with overlap checks.
3117 int InitializeNode::captured_store_insertion_point(intptr_t start,
3118 int size_in_bytes,
3119 PhaseTransform* phase) {
3120 const int FAIL = 0, MAX_STORE = BytesPerLong;
3121
3122 if (is_complete())
3123 return FAIL; // arraycopy got here first; punt
3124
3125 assert(allocation() != NULL, "must be present");
3126
3127 // no negatives, no header fields:
3128 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
3129
3130 // after a certain size, we bail out on tracking all the stores:
3131 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3132 if (start >= ti_limit) return FAIL;
3133
3134 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
3135 if (i >= limit) return -(int)i; // not found; here is where to put it
3136
3137 Node* st = in(i);
3138 intptr_t st_off = get_store_offset(st, phase);
3139 if (st_off < 0) {
3140 if (st != zero_memory()) {
3141 return FAIL; // bail out if there is dead garbage
3142 }
3143 } else if (st_off > start) {
3144 // ...we are done, since stores are ordered
3145 if (st_off < start + size_in_bytes) {
3146 return FAIL; // the next store overlaps
3147 }
3148 return -(int)i; // not found; here is where to put it
3149 } else if (st_off < start) {
3150 if (size_in_bytes != 0 &&
3151 start < st_off + MAX_STORE &&
3152 start < st_off + st->as_Store()->memory_size()) {
3153 return FAIL; // the previous store overlaps
3154 }
3155 } else {
3156 if (size_in_bytes != 0 &&
3157 st->as_Store()->memory_size() != size_in_bytes) {
3158 return FAIL; // mismatched store size
3159 }
3160 return i;
3161 }
3162
3163 ++i;
3164 }
3165 }
3166
3167 // Look for a captured store which initializes at the offset 'start'
3168 // with the given size. If there is no such store, and no other
3169 // initialization interferes, then return zero_memory (the memory
3170 // projection of the AllocateNode).
3171 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
3172 PhaseTransform* phase) {
3173 assert(stores_are_sane(phase), "");
3174 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3175 if (i == 0) {
3176 return NULL; // something is dead
3177 } else if (i < 0) {
3178 return zero_memory(); // just primordial zero bits here
3179 } else {
3180 Node* st = in(i); // here is the store at this position
3181 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
3182 return st;
3183 }
3184 }
3185
3186 // Create, as a raw pointer, an address within my new object at 'offset'.
3187 Node* InitializeNode::make_raw_address(intptr_t offset,
3188 PhaseTransform* phase) {
3189 Node* addr = in(RawAddress);
3190 if (offset != 0) {
3191 Compile* C = phase->C;
3192 addr = phase->transform( new (C) AddPNode(C->top(), addr,
3193 phase->MakeConX(offset)) );
3194 }
3195 return addr;
3196 }
3197
3198 // Clone the given store, converting it into a raw store
3199 // initializing a field or element of my new object.
3200 // Caller is responsible for retiring the original store,
3201 // with subsume_node or the like.
3202 //
3203 // From the example above InitializeNode::InitializeNode,
3204 // here are the old stores to be captured:
3205 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3206 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3207 //
3208 // Here is the changed code; note the extra edges on init:
3209 // alloc = (Allocate ...)
3210 // rawoop = alloc.RawAddress
3211 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
3212 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
3213 // init = (Initialize alloc.Control alloc.Memory rawoop
3214 // rawstore1 rawstore2)
3215 //
3216 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
3217 PhaseTransform* phase) {
3218 assert(stores_are_sane(phase), "");
3219
3220 if (start < 0) return NULL;
3221 assert(can_capture_store(st, phase) == start, "sanity");
3222
3223 Compile* C = phase->C;
3224 int size_in_bytes = st->memory_size();
3225 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3226 if (i == 0) return NULL; // bail out
3227 Node* prev_mem = NULL; // raw memory for the captured store
3228 if (i > 0) {
3229 prev_mem = in(i); // there is a pre-existing store under this one
3230 set_req(i, C->top()); // temporarily disconnect it
3231 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
3232 } else {
3233 i = -i; // no pre-existing store
3234 prev_mem = zero_memory(); // a slice of the newly allocated object
3235 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
3236 set_req(--i, C->top()); // reuse this edge; it has been folded away
3237 else
3238 ins_req(i, C->top()); // build a new edge
3239 }
3240 Node* new_st = st->clone();
3241 new_st->set_req(MemNode::Control, in(Control));
3242 new_st->set_req(MemNode::Memory, prev_mem);
3243 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
3244 new_st = phase->transform(new_st);
3245
3246 // At this point, new_st might have swallowed a pre-existing store
3247 // at the same offset, or perhaps new_st might have disappeared,
3248 // if it redundantly stored the same value (or zero to fresh memory).
3249
3250 // In any case, wire it in:
3251 set_req(i, new_st);
3252
3253 // The caller may now kill the old guy.
3254 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
3255 assert(check_st == new_st || check_st == NULL, "must be findable");
3256 assert(!is_complete(), "");
3257 return new_st;
3258 }
3259
3260 static bool store_constant(jlong* tiles, int num_tiles,
3261 intptr_t st_off, int st_size,
3262 jlong con) {
3263 if ((st_off & (st_size-1)) != 0)
3264 return false; // strange store offset (assume size==2**N)
3265 address addr = (address)tiles + st_off;
3266 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
3267 switch (st_size) {
3268 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
3269 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
3270 case sizeof(jint): *(jint*) addr = (jint) con; break;
3271 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
3272 default: return false; // strange store size (detect size!=2**N here)
3273 }
3274 return true; // return success to caller
3275 }
3276
3277 // Coalesce subword constants into int constants and possibly
3278 // into long constants. The goal, if the CPU permits,
3279 // is to initialize the object with a small number of 64-bit tiles.
3280 // Also, convert floating-point constants to bit patterns.
3281 // Non-constants are not relevant to this pass.
3282 //
3283 // In terms of the running example on InitializeNode::InitializeNode
3284 // and InitializeNode::capture_store, here is the transformation
3285 // of rawstore1 and rawstore2 into rawstore12:
3286 // alloc = (Allocate ...)
3287 // rawoop = alloc.RawAddress
3288 // tile12 = 0x00010002
3289 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
3290 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
3291 //
3292 void
3293 InitializeNode::coalesce_subword_stores(intptr_t header_size,
3294 Node* size_in_bytes,
3295 PhaseGVN* phase) {
3296 Compile* C = phase->C;
3297
3298 assert(stores_are_sane(phase), "");
3299 // Note: After this pass, they are not completely sane,
3300 // since there may be some overlaps.
3301
3302 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
3303
3304 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3305 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
3306 size_limit = MIN2(size_limit, ti_limit);
3307 size_limit = align_size_up(size_limit, BytesPerLong);
3308 int num_tiles = size_limit / BytesPerLong;
3309
3310 // allocate space for the tile map:
3311 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
3312 jlong tiles_buf[small_len];
3313 Node* nodes_buf[small_len];
3314 jlong inits_buf[small_len];
3315 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
3316 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3317 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
3318 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
3319 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
3320 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3321 // tiles: exact bitwise model of all primitive constants
3322 // nodes: last constant-storing node subsumed into the tiles model
3323 // inits: which bytes (in each tile) are touched by any initializations
3324
3325 //// Pass A: Fill in the tile model with any relevant stores.
3326
3327 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
3328 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
3329 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
3330 Node* zmem = zero_memory(); // initially zero memory state
3331 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3332 Node* st = in(i);
3333 intptr_t st_off = get_store_offset(st, phase);
3334
3335 // Figure out the store's offset and constant value:
3336 if (st_off < header_size) continue; //skip (ignore header)
3337 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
3338 int st_size = st->as_Store()->memory_size();
3339 if (st_off + st_size > size_limit) break;
3340
3341 // Record which bytes are touched, whether by constant or not.
3342 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
3343 continue; // skip (strange store size)
3344
3345 const Type* val = phase->type(st->in(MemNode::ValueIn));
3346 if (!val->singleton()) continue; //skip (non-con store)
3347 BasicType type = val->basic_type();
3348
3349 jlong con = 0;
3350 switch (type) {
3351 case T_INT: con = val->is_int()->get_con(); break;
3352 case T_LONG: con = val->is_long()->get_con(); break;
3353 case T_FLOAT: con = jint_cast(val->getf()); break;
3354 case T_DOUBLE: con = jlong_cast(val->getd()); break;
3355 default: continue; //skip (odd store type)
3356 }
3357
3358 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
3359 st->Opcode() == Op_StoreL) {
3360 continue; // This StoreL is already optimal.
3361 }
3362
3363 // Store down the constant.
3364 store_constant(tiles, num_tiles, st_off, st_size, con);
3365
3366 intptr_t j = st_off >> LogBytesPerLong;
3367
3368 if (type == T_INT && st_size == BytesPerInt
3369 && (st_off & BytesPerInt) == BytesPerInt) {
3370 jlong lcon = tiles[j];
3371 if (!Matcher::isSimpleConstant64(lcon) &&
3372 st->Opcode() == Op_StoreI) {
3373 // This StoreI is already optimal by itself.
3374 jint* intcon = (jint*) &tiles[j];
3375 intcon[1] = 0; // undo the store_constant()
3376
3377 // If the previous store is also optimal by itself, back up and
3378 // undo the action of the previous loop iteration... if we can.
3379 // But if we can't, just let the previous half take care of itself.
3380 st = nodes[j];
3381 st_off -= BytesPerInt;
3382 con = intcon[0];
3383 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) {
3384 assert(st_off >= header_size, "still ignoring header");
3385 assert(get_store_offset(st, phase) == st_off, "must be");
3386 assert(in(i-1) == zmem, "must be");
3387 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
3388 assert(con == tcon->is_int()->get_con(), "must be");
3389 // Undo the effects of the previous loop trip, which swallowed st:
3390 intcon[0] = 0; // undo store_constant()
3391 set_req(i-1, st); // undo set_req(i, zmem)
3392 nodes[j] = NULL; // undo nodes[j] = st
3393 --old_subword; // undo ++old_subword
3394 }
3395 continue; // This StoreI is already optimal.
3396 }
3397 }
3398
3399 // This store is not needed.
3400 set_req(i, zmem);
3401 nodes[j] = st; // record for the moment
3402 if (st_size < BytesPerLong) // something has changed
3403 ++old_subword; // includes int/float, but who's counting...
3404 else ++old_long;
3405 }
3406
3407 if ((old_subword + old_long) == 0)
3408 return; // nothing more to do
3409
3410 //// Pass B: Convert any non-zero tiles into optimal constant stores.
3411 // Be sure to insert them before overlapping non-constant stores.
3412 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
3413 for (int j = 0; j < num_tiles; j++) {
3414 jlong con = tiles[j];
3415 jlong init = inits[j];
3416 if (con == 0) continue;
3417 jint con0, con1; // split the constant, address-wise
3418 jint init0, init1; // split the init map, address-wise
3419 { union { jlong con; jint intcon[2]; } u;
3420 u.con = con;
3421 con0 = u.intcon[0];
3422 con1 = u.intcon[1];
3423 u.con = init;
3424 init0 = u.intcon[0];
3425 init1 = u.intcon[1];
3426 }
3427
3428 Node* old = nodes[j];
3429 assert(old != NULL, "need the prior store");
3430 intptr_t offset = (j * BytesPerLong);
3431
3432 bool split = !Matcher::isSimpleConstant64(con);
3433
3434 if (offset < header_size) {
3435 assert(offset + BytesPerInt >= header_size, "second int counts");
3436 assert(*(jint*)&tiles[j] == 0, "junk in header");
3437 split = true; // only the second word counts
3438 // Example: int a[] = { 42 ... }
3439 } else if (con0 == 0 && init0 == -1) {
3440 split = true; // first word is covered by full inits
3441 // Example: int a[] = { ... foo(), 42 ... }
3442 } else if (con1 == 0 && init1 == -1) {
3443 split = true; // second word is covered by full inits
3444 // Example: int a[] = { ... 42, foo() ... }
3445 }
3446
3447 // Here's a case where init0 is neither 0 nor -1:
3448 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
3449 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
3450 // In this case the tile is not split; it is (jlong)42.
3451 // The big tile is stored down, and then the foo() value is inserted.
3452 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
3453
3454 Node* ctl = old->in(MemNode::Control);
3455 Node* adr = make_raw_address(offset, phase);
3456 const TypePtr* atp = TypeRawPtr::BOTTOM;
3457
3458 // One or two coalesced stores to plop down.
3459 Node* st[2];
3460 intptr_t off[2];
3461 int nst = 0;
3462 if (!split) {
3463 ++new_long;
3464 off[nst] = offset;
3465 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3466 phase->longcon(con), T_LONG);
3467 } else {
3468 // Omit either if it is a zero.
3469 if (con0 != 0) {
3470 ++new_int;
3471 off[nst] = offset;
3472 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3473 phase->intcon(con0), T_INT);
3474 }
3475 if (con1 != 0) {
3476 ++new_int;
3477 offset += BytesPerInt;
3478 adr = make_raw_address(offset, phase);
3479 off[nst] = offset;
3480 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3481 phase->intcon(con1), T_INT);
3482 }
3483 }
3484
3485 // Insert second store first, then the first before the second.
3486 // Insert each one just before any overlapping non-constant stores.
3487 while (nst > 0) {
3488 Node* st1 = st[--nst];
3489 C->copy_node_notes_to(st1, old);
3490 st1 = phase->transform(st1);
3491 offset = off[nst];
3492 assert(offset >= header_size, "do not smash header");
3493 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
3494 guarantee(ins_idx != 0, "must re-insert constant store");
3495 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
3496 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
3497 set_req(--ins_idx, st1);
3498 else
3499 ins_req(ins_idx, st1);
3500 }
3501 }
3502
3503 if (PrintCompilation && WizardMode)
3504 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
3505 old_subword, old_long, new_int, new_long);
3506 if (C->log() != NULL)
3507 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
3508 old_subword, old_long, new_int, new_long);
3509
3510 // Clean up any remaining occurrences of zmem:
3511 remove_extra_zeroes();
3512 }
3513
3514 // Explore forward from in(start) to find the first fully initialized
3515 // word, and return its offset. Skip groups of subword stores which
3516 // together initialize full words. If in(start) is itself part of a
3517 // fully initialized word, return the offset of in(start). If there
3518 // are no following full-word stores, or if something is fishy, return
3519 // a negative value.
3520 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
3521 int int_map = 0;
3522 intptr_t int_map_off = 0;
3523 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
3524
3525 for (uint i = start, limit = req(); i < limit; i++) {
3526 Node* st = in(i);
3527
3528 intptr_t st_off = get_store_offset(st, phase);
3529 if (st_off < 0) break; // return conservative answer
3530
3531 int st_size = st->as_Store()->memory_size();
3532 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
3533 return st_off; // we found a complete word init
3534 }
3535
3536 // update the map:
3537
3538 intptr_t this_int_off = align_size_down(st_off, BytesPerInt);
3539 if (this_int_off != int_map_off) {
3540 // reset the map:
3541 int_map = 0;
3542 int_map_off = this_int_off;
3543 }
3544
3545 int subword_off = st_off - this_int_off;
3546 int_map |= right_n_bits(st_size) << subword_off;
3547 if ((int_map & FULL_MAP) == FULL_MAP) {
3548 return this_int_off; // we found a complete word init
3549 }
3550
3551 // Did this store hit or cross the word boundary?
3552 intptr_t next_int_off = align_size_down(st_off + st_size, BytesPerInt);
3553 if (next_int_off == this_int_off + BytesPerInt) {
3554 // We passed the current int, without fully initializing it.
3555 int_map_off = next_int_off;
3556 int_map >>= BytesPerInt;
3557 } else if (next_int_off > this_int_off + BytesPerInt) {
3558 // We passed the current and next int.
3559 return this_int_off + BytesPerInt;
3560 }
3561 }
3562
3563 return -1;
3564 }
3565
3566
3567 // Called when the associated AllocateNode is expanded into CFG.
3568 // At this point, we may perform additional optimizations.
3569 // Linearize the stores by ascending offset, to make memory
3570 // activity as coherent as possible.
3571 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
3572 intptr_t header_size,
3573 Node* size_in_bytes,
3574 PhaseGVN* phase) {
3575 assert(!is_complete(), "not already complete");
3576 assert(stores_are_sane(phase), "");
3577 assert(allocation() != NULL, "must be present");
3578
3579 remove_extra_zeroes();
3580
3581 if (ReduceFieldZeroing || ReduceBulkZeroing)
3582 // reduce instruction count for common initialization patterns
3583 coalesce_subword_stores(header_size, size_in_bytes, phase);
3584
3585 Node* zmem = zero_memory(); // initially zero memory state
3586 Node* inits = zmem; // accumulating a linearized chain of inits
3587 #ifdef ASSERT
3588 intptr_t first_offset = allocation()->minimum_header_size();
3589 intptr_t last_init_off = first_offset; // previous init offset
3590 intptr_t last_init_end = first_offset; // previous init offset+size
3591 intptr_t last_tile_end = first_offset; // previous tile offset+size
3592 #endif
3593 intptr_t zeroes_done = header_size;
3594
3595 bool do_zeroing = true; // we might give up if inits are very sparse
3596 int big_init_gaps = 0; // how many large gaps have we seen?
3597
3598 if (ZeroTLAB) do_zeroing = false;
3599 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
3600
3601 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3602 Node* st = in(i);
3603 intptr_t st_off = get_store_offset(st, phase);
3604 if (st_off < 0)
3605 break; // unknown junk in the inits
3606 if (st->in(MemNode::Memory) != zmem)
3607 break; // complicated store chains somehow in list
3608
3609 int st_size = st->as_Store()->memory_size();
3610 intptr_t next_init_off = st_off + st_size;
3611
3612 if (do_zeroing && zeroes_done < next_init_off) {
3613 // See if this store needs a zero before it or under it.
3614 intptr_t zeroes_needed = st_off;
3615
3616 if (st_size < BytesPerInt) {
3617 // Look for subword stores which only partially initialize words.
3618 // If we find some, we must lay down some word-level zeroes first,
3619 // underneath the subword stores.
3620 //
3621 // Examples:
3622 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
3623 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
3624 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
3625 //
3626 // Note: coalesce_subword_stores may have already done this,
3627 // if it was prompted by constant non-zero subword initializers.
3628 // But this case can still arise with non-constant stores.
3629
3630 intptr_t next_full_store = find_next_fullword_store(i, phase);
3631
3632 // In the examples above:
3633 // in(i) p q r s x y z
3634 // st_off 12 13 14 15 12 13 14
3635 // st_size 1 1 1 1 1 1 1
3636 // next_full_s. 12 16 16 16 16 16 16
3637 // z's_done 12 16 16 16 12 16 12
3638 // z's_needed 12 16 16 16 16 16 16
3639 // zsize 0 0 0 0 4 0 4
3640 if (next_full_store < 0) {
3641 // Conservative tack: Zero to end of current word.
3642 zeroes_needed = align_size_up(zeroes_needed, BytesPerInt);
3643 } else {
3644 // Zero to beginning of next fully initialized word.
3645 // Or, don't zero at all, if we are already in that word.
3646 assert(next_full_store >= zeroes_needed, "must go forward");
3647 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
3648 zeroes_needed = next_full_store;
3649 }
3650 }
3651
3652 if (zeroes_needed > zeroes_done) {
3653 intptr_t zsize = zeroes_needed - zeroes_done;
3654 // Do some incremental zeroing on rawmem, in parallel with inits.
3655 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3656 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3657 zeroes_done, zeroes_needed,
3658 phase);
3659 zeroes_done = zeroes_needed;
3660 if (zsize > Matcher::init_array_short_size && ++big_init_gaps > 2)
3661 do_zeroing = false; // leave the hole, next time
3662 }
3663 }
3664
3665 // Collect the store and move on:
3666 st->set_req(MemNode::Memory, inits);
3667 inits = st; // put it on the linearized chain
3668 set_req(i, zmem); // unhook from previous position
3669
3670 if (zeroes_done == st_off)
3671 zeroes_done = next_init_off;
3672
3673 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
3674
3675 #ifdef ASSERT
3676 // Various order invariants. Weaker than stores_are_sane because
3677 // a large constant tile can be filled in by smaller non-constant stores.
3678 assert(st_off >= last_init_off, "inits do not reverse");
3679 last_init_off = st_off;
3680 const Type* val = NULL;
3681 if (st_size >= BytesPerInt &&
3682 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
3683 (int)val->basic_type() < (int)T_OBJECT) {
3684 assert(st_off >= last_tile_end, "tiles do not overlap");
3685 assert(st_off >= last_init_end, "tiles do not overwrite inits");
3686 last_tile_end = MAX2(last_tile_end, next_init_off);
3687 } else {
3688 intptr_t st_tile_end = align_size_up(next_init_off, BytesPerLong);
3689 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
3690 assert(st_off >= last_init_end, "inits do not overlap");
3691 last_init_end = next_init_off; // it's a non-tile
3692 }
3693 #endif //ASSERT
3694 }
3695
3696 remove_extra_zeroes(); // clear out all the zmems left over
3697 add_req(inits);
3698
3699 if (!ZeroTLAB) {
3700 // If anything remains to be zeroed, zero it all now.
3701 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3702 // if it is the last unused 4 bytes of an instance, forget about it
3703 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
3704 if (zeroes_done + BytesPerLong >= size_limit) {
3705 assert(allocation() != NULL, "");
3706 if (allocation()->Opcode() == Op_Allocate) {
3707 Node* klass_node = allocation()->in(AllocateNode::KlassNode);
3708 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass();
3709 if (zeroes_done == k->layout_helper())
3710 zeroes_done = size_limit;
3711 }
3712 }
3713 if (zeroes_done < size_limit) {
3714 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3715 zeroes_done, size_in_bytes, phase);
3716 }
3717 }
3718
3719 set_complete(phase);
3720 return rawmem;
3721 }
3722
3723
3724 #ifdef ASSERT
3725 bool InitializeNode::stores_are_sane(PhaseTransform* phase) {
3726 if (is_complete())
3727 return true; // stores could be anything at this point
3728 assert(allocation() != NULL, "must be present");
3729 intptr_t last_off = allocation()->minimum_header_size();
3730 for (uint i = InitializeNode::RawStores; i < req(); i++) {
3731 Node* st = in(i);
3732 intptr_t st_off = get_store_offset(st, phase);
3733 if (st_off < 0) continue; // ignore dead garbage
3734 if (last_off > st_off) {
3735 tty->print_cr("*** bad store offset at %d: %d > %d", i, last_off, st_off);
3736 this->dump(2);
3737 assert(false, "ascending store offsets");
3738 return false;
3739 }
3740 last_off = st_off + st->as_Store()->memory_size();
3741 }
3742 return true;
3743 }
3744 #endif //ASSERT
3745
3746
3747
3748
3749 //============================MergeMemNode=====================================
3750 //
3751 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
3752 // contributing store or call operations. Each contributor provides the memory
3753 // state for a particular "alias type" (see Compile::alias_type). For example,
3754 // if a MergeMem has an input X for alias category #6, then any memory reference
3755 // to alias category #6 may use X as its memory state input, as an exact equivalent
3756 // to using the MergeMem as a whole.
3757 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
3758 //
3759 // (Here, the <N> notation gives the index of the relevant adr_type.)
3760 //
3761 // In one special case (and more cases in the future), alias categories overlap.
3762 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
3763 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
3764 // it is exactly equivalent to that state W:
3765 // MergeMem(<Bot>: W) <==> W
3766 //
3767 // Usually, the merge has more than one input. In that case, where inputs
3768 // overlap (i.e., one is Bot), the narrower alias type determines the memory
3769 // state for that type, and the wider alias type (Bot) fills in everywhere else:
3770 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
3771 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
3772 //
3773 // A merge can take a "wide" memory state as one of its narrow inputs.
3774 // This simply means that the merge observes out only the relevant parts of
3775 // the wide input. That is, wide memory states arriving at narrow merge inputs
3776 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
3777 //
3778 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
3779 // and that memory slices "leak through":
3780 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
3781 //
3782 // But, in such a cascade, repeated memory slices can "block the leak":
3783 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
3784 //
3785 // In the last example, Y is not part of the combined memory state of the
3786 // outermost MergeMem. The system must, of course, prevent unschedulable
3787 // memory states from arising, so you can be sure that the state Y is somehow
3788 // a precursor to state Y'.
3789 //
3790 //
3791 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
3792 // of each MergeMemNode array are exactly the numerical alias indexes, including
3793 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
3794 // Compile::alias_type (and kin) produce and manage these indexes.
3795 //
3796 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
3797 // (Note that this provides quick access to the top node inside MergeMem methods,
3798 // without the need to reach out via TLS to Compile::current.)
3799 //
3800 // As a consequence of what was just described, a MergeMem that represents a full
3801 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
3802 // containing all alias categories.
3803 //
3804 // MergeMem nodes never (?) have control inputs, so in(0) is NULL.
3805 //
3806 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
3807 // a memory state for the alias type <N>, or else the top node, meaning that
3808 // there is no particular input for that alias type. Note that the length of
3809 // a MergeMem is variable, and may be extended at any time to accommodate new
3810 // memory states at larger alias indexes. When merges grow, they are of course
3811 // filled with "top" in the unused in() positions.
3812 //
3813 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
3814 // (Top was chosen because it works smoothly with passes like GCM.)
3815 //
3816 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
3817 // the type of random VM bits like TLS references.) Since it is always the
3818 // first non-Bot memory slice, some low-level loops use it to initialize an
3819 // index variable: for (i = AliasIdxRaw; i < req(); i++).
3820 //
3821 //
3822 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
3823 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
3824 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
3825 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
3826 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
3827 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
3828 //
3829 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
3830 // really that different from the other memory inputs. An abbreviation called
3831 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
3832 //
3833 //
3834 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
3835 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
3836 // that "emerges though" the base memory will be marked as excluding the alias types
3837 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
3838 //
3839 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
3840 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
3841 //
3842 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
3843 // (It is currently unimplemented.) As you can see, the resulting merge is
3844 // actually a disjoint union of memory states, rather than an overlay.
3845 //
3846
3847 //------------------------------MergeMemNode-----------------------------------
3848 Node* MergeMemNode::make_empty_memory() {
3849 Node* empty_memory = (Node*) Compile::current()->top();
3850 assert(empty_memory->is_top(), "correct sentinel identity");
3851 return empty_memory;
3852 }
3853
3854 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
3855 init_class_id(Class_MergeMem);
3856 // all inputs are nullified in Node::Node(int)
3857 // set_input(0, NULL); // no control input
3858
3859 // Initialize the edges uniformly to top, for starters.
3860 Node* empty_mem = make_empty_memory();
3861 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
3862 init_req(i,empty_mem);
3863 }
3864 assert(empty_memory() == empty_mem, "");
3865
3866 if( new_base != NULL && new_base->is_MergeMem() ) {
3867 MergeMemNode* mdef = new_base->as_MergeMem();
3868 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
3869 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
3870 mms.set_memory(mms.memory2());
3871 }
3872 assert(base_memory() == mdef->base_memory(), "");
3873 } else {
3874 set_base_memory(new_base);
3875 }
3876 }
3877
3878 // Make a new, untransformed MergeMem with the same base as 'mem'.
3879 // If mem is itself a MergeMem, populate the result with the same edges.
3880 MergeMemNode* MergeMemNode::make(Compile* C, Node* mem) {
3881 return new(C) MergeMemNode(mem);
3882 }
3883
3884 //------------------------------cmp--------------------------------------------
3885 uint MergeMemNode::hash() const { return NO_HASH; }
3886 uint MergeMemNode::cmp( const Node &n ) const {
3887 return (&n == this); // Always fail except on self
3888 }
3889
3890 //------------------------------Identity---------------------------------------
3891 Node* MergeMemNode::Identity(PhaseTransform *phase) {
3892 // Identity if this merge point does not record any interesting memory
3893 // disambiguations.
3894 Node* base_mem = base_memory();
3895 Node* empty_mem = empty_memory();
3896 if (base_mem != empty_mem) { // Memory path is not dead?
3897 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3898 Node* mem = in(i);
3899 if (mem != empty_mem && mem != base_mem) {
3900 return this; // Many memory splits; no change
3901 }
3902 }
3903 }
3904 return base_mem; // No memory splits; ID on the one true input
3905 }
3906
3907 //------------------------------Ideal------------------------------------------
3908 // This method is invoked recursively on chains of MergeMem nodes
3909 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3910 // Remove chain'd MergeMems
3911 //
3912 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
3913 // relative to the "in(Bot)". Since we are patching both at the same time,
3914 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
3915 // but rewrite each "in(i)" relative to the new "in(Bot)".
3916 Node *progress = NULL;
3917
3918
3919 Node* old_base = base_memory();
3920 Node* empty_mem = empty_memory();
3921 if (old_base == empty_mem)
3922 return NULL; // Dead memory path.
3923
3924 MergeMemNode* old_mbase;
3925 if (old_base != NULL && old_base->is_MergeMem())
3926 old_mbase = old_base->as_MergeMem();
3927 else
3928 old_mbase = NULL;
3929 Node* new_base = old_base;
3930
3931 // simplify stacked MergeMems in base memory
3932 if (old_mbase) new_base = old_mbase->base_memory();
3933
3934 // the base memory might contribute new slices beyond my req()
3935 if (old_mbase) grow_to_match(old_mbase);
3936
3937 // Look carefully at the base node if it is a phi.
3938 PhiNode* phi_base;
3939 if (new_base != NULL && new_base->is_Phi())
3940 phi_base = new_base->as_Phi();
3941 else
3942 phi_base = NULL;
3943
3944 Node* phi_reg = NULL;
3945 uint phi_len = (uint)-1;
3946 if (phi_base != NULL && !phi_base->is_copy()) {
3947 // do not examine phi if degraded to a copy
3948 phi_reg = phi_base->region();
3949 phi_len = phi_base->req();
3950 // see if the phi is unfinished
3951 for (uint i = 1; i < phi_len; i++) {
3952 if (phi_base->in(i) == NULL) {
3953 // incomplete phi; do not look at it yet!
3954 phi_reg = NULL;
3955 phi_len = (uint)-1;
3956 break;
3957 }
3958 }
3959 }
3960
3961 // Note: We do not call verify_sparse on entry, because inputs
3962 // can normalize to the base_memory via subsume_node or similar
3963 // mechanisms. This method repairs that damage.
3964
3965 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
3966
3967 // Look at each slice.
3968 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3969 Node* old_in = in(i);
3970 // calculate the old memory value
3971 Node* old_mem = old_in;
3972 if (old_mem == empty_mem) old_mem = old_base;
3973 assert(old_mem == memory_at(i), "");
3974
3975 // maybe update (reslice) the old memory value
3976
3977 // simplify stacked MergeMems
3978 Node* new_mem = old_mem;
3979 MergeMemNode* old_mmem;
3980 if (old_mem != NULL && old_mem->is_MergeMem())
3981 old_mmem = old_mem->as_MergeMem();
3982 else
3983 old_mmem = NULL;
3984 if (old_mmem == this) {
3985 // This can happen if loops break up and safepoints disappear.
3986 // A merge of BotPtr (default) with a RawPtr memory derived from a
3987 // safepoint can be rewritten to a merge of the same BotPtr with
3988 // the BotPtr phi coming into the loop. If that phi disappears
3989 // also, we can end up with a self-loop of the mergemem.
3990 // In general, if loops degenerate and memory effects disappear,
3991 // a mergemem can be left looking at itself. This simply means
3992 // that the mergemem's default should be used, since there is
3993 // no longer any apparent effect on this slice.
3994 // Note: If a memory slice is a MergeMem cycle, it is unreachable
3995 // from start. Update the input to TOP.
3996 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
3997 }
3998 else if (old_mmem != NULL) {
3999 new_mem = old_mmem->memory_at(i);
4000 }
4001 // else preceding memory was not a MergeMem
4002
4003 // replace equivalent phis (unfortunately, they do not GVN together)
4004 if (new_mem != NULL && new_mem != new_base &&
4005 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) {
4006 if (new_mem->is_Phi()) {
4007 PhiNode* phi_mem = new_mem->as_Phi();
4008 for (uint i = 1; i < phi_len; i++) {
4009 if (phi_base->in(i) != phi_mem->in(i)) {
4010 phi_mem = NULL;
4011 break;
4012 }
4013 }
4014 if (phi_mem != NULL) {
4015 // equivalent phi nodes; revert to the def
4016 new_mem = new_base;
4017 }
4018 }
4019 }
4020
4021 // maybe store down a new value
4022 Node* new_in = new_mem;
4023 if (new_in == new_base) new_in = empty_mem;
4024
4025 if (new_in != old_in) {
4026 // Warning: Do not combine this "if" with the previous "if"
4027 // A memory slice might have be be rewritten even if it is semantically
4028 // unchanged, if the base_memory value has changed.
4029 set_req(i, new_in);
4030 progress = this; // Report progress
4031 }
4032 }
4033
4034 if (new_base != old_base) {
4035 set_req(Compile::AliasIdxBot, new_base);
4036 // Don't use set_base_memory(new_base), because we need to update du.
4037 assert(base_memory() == new_base, "");
4038 progress = this;
4039 }
4040
4041 if( base_memory() == this ) {
4042 // a self cycle indicates this memory path is dead
4043 set_req(Compile::AliasIdxBot, empty_mem);
4044 }
4045
4046 // Resolve external cycles by calling Ideal on a MergeMem base_memory
4047 // Recursion must occur after the self cycle check above
4048 if( base_memory()->is_MergeMem() ) {
4049 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
4050 Node *m = phase->transform(new_mbase); // Rollup any cycles
4051 if( m != NULL && (m->is_top() ||
4052 m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem) ) {
4053 // propagate rollup of dead cycle to self
4054 set_req(Compile::AliasIdxBot, empty_mem);
4055 }
4056 }
4057
4058 if( base_memory() == empty_mem ) {
4059 progress = this;
4060 // Cut inputs during Parse phase only.
4061 // During Optimize phase a dead MergeMem node will be subsumed by Top.
4062 if( !can_reshape ) {
4063 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4064 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
4065 }
4066 }
4067 }
4068
4069 if( !progress && base_memory()->is_Phi() && can_reshape ) {
4070 // Check if PhiNode::Ideal's "Split phis through memory merges"
4071 // transform should be attempted. Look for this->phi->this cycle.
4072 uint merge_width = req();
4073 if (merge_width > Compile::AliasIdxRaw) {
4074 PhiNode* phi = base_memory()->as_Phi();
4075 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
4076 if (phi->in(i) == this) {
4077 phase->is_IterGVN()->_worklist.push(phi);
4078 break;
4079 }
4080 }
4081 }
4082 }
4083
4084 assert(progress || verify_sparse(), "please, no dups of base");
4085 return progress;
4086 }
4087
4088 //-------------------------set_base_memory-------------------------------------
4089 void MergeMemNode::set_base_memory(Node *new_base) {
4090 Node* empty_mem = empty_memory();
4091 set_req(Compile::AliasIdxBot, new_base);
4092 assert(memory_at(req()) == new_base, "must set default memory");
4093 // Clear out other occurrences of new_base:
4094 if (new_base != empty_mem) {
4095 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4096 if (in(i) == new_base) set_req(i, empty_mem);
4097 }
4098 }
4099 }
4100
4101 //------------------------------out_RegMask------------------------------------
4102 const RegMask &MergeMemNode::out_RegMask() const {
4103 return RegMask::Empty;
4104 }
4105
4106 //------------------------------dump_spec--------------------------------------
4107 #ifndef PRODUCT
4108 void MergeMemNode::dump_spec(outputStream *st) const {
4109 st->print(" {");
4110 Node* base_mem = base_memory();
4111 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
4112 Node* mem = memory_at(i);
4113 if (mem == base_mem) { st->print(" -"); continue; }
4114 st->print( " N%d:", mem->_idx );
4115 Compile::current()->get_adr_type(i)->dump_on(st);
4116 }
4117 st->print(" }");
4118 }
4119 #endif // !PRODUCT
4120
4121
4122 #ifdef ASSERT
4123 static bool might_be_same(Node* a, Node* b) {
4124 if (a == b) return true;
4125 if (!(a->is_Phi() || b->is_Phi())) return false;
4126 // phis shift around during optimization
4127 return true; // pretty stupid...
4128 }
4129
4130 // verify a narrow slice (either incoming or outgoing)
4131 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
4132 if (!VerifyAliases) return; // don't bother to verify unless requested
4133 if (is_error_reported()) return; // muzzle asserts when debugging an error
4134 if (Node::in_dump()) return; // muzzle asserts when printing
4135 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
4136 assert(n != NULL, "");
4137 // Elide intervening MergeMem's
4138 while (n->is_MergeMem()) {
4139 n = n->as_MergeMem()->memory_at(alias_idx);
4140 }
4141 Compile* C = Compile::current();
4142 const TypePtr* n_adr_type = n->adr_type();
4143 if (n == m->empty_memory()) {
4144 // Implicit copy of base_memory()
4145 } else if (n_adr_type != TypePtr::BOTTOM) {
4146 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type");
4147 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
4148 } else {
4149 // A few places like make_runtime_call "know" that VM calls are narrow,
4150 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
4151 bool expected_wide_mem = false;
4152 if (n == m->base_memory()) {
4153 expected_wide_mem = true;
4154 } else if (alias_idx == Compile::AliasIdxRaw ||
4155 n == m->memory_at(Compile::AliasIdxRaw)) {
4156 expected_wide_mem = true;
4157 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
4158 // memory can "leak through" calls on channels that
4159 // are write-once. Allow this also.
4160 expected_wide_mem = true;
4161 }
4162 assert(expected_wide_mem, "expected narrow slice replacement");
4163 }
4164 }
4165 #else // !ASSERT
4166 #define verify_memory_slice(m,i,n) (0) // PRODUCT version is no-op
4167 #endif
4168
4169
4170 //-----------------------------memory_at---------------------------------------
4171 Node* MergeMemNode::memory_at(uint alias_idx) const {
4172 assert(alias_idx >= Compile::AliasIdxRaw ||
4173 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0,
4174 "must avoid base_memory and AliasIdxTop");
4175
4176 // Otherwise, it is a narrow slice.
4177 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
4178 Compile *C = Compile::current();
4179 if (is_empty_memory(n)) {
4180 // the array is sparse; empty slots are the "top" node
4181 n = base_memory();
4182 assert(Node::in_dump()
4183 || n == NULL || n->bottom_type() == Type::TOP
4184 || n->adr_type() == NULL // address is TOP
4185 || n->adr_type() == TypePtr::BOTTOM
4186 || n->adr_type() == TypeRawPtr::BOTTOM
4187 || Compile::current()->AliasLevel() == 0,
4188 "must be a wide memory");
4189 // AliasLevel == 0 if we are organizing the memory states manually.
4190 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
4191 } else {
4192 // make sure the stored slice is sane
4193 #ifdef ASSERT
4194 if (is_error_reported() || Node::in_dump()) {
4195 } else if (might_be_same(n, base_memory())) {
4196 // Give it a pass: It is a mostly harmless repetition of the base.
4197 // This can arise normally from node subsumption during optimization.
4198 } else {
4199 verify_memory_slice(this, alias_idx, n);
4200 }
4201 #endif
4202 }
4203 return n;
4204 }
4205
4206 //---------------------------set_memory_at-------------------------------------
4207 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
4208 verify_memory_slice(this, alias_idx, n);
4209 Node* empty_mem = empty_memory();
4210 if (n == base_memory()) n = empty_mem; // collapse default
4211 uint need_req = alias_idx+1;
4212 if (req() < need_req) {
4213 if (n == empty_mem) return; // already the default, so do not grow me
4214 // grow the sparse array
4215 do {
4216 add_req(empty_mem);
4217 } while (req() < need_req);
4218 }
4219 set_req( alias_idx, n );
4220 }
4221
4222
4223
4224 //--------------------------iteration_setup------------------------------------
4225 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
4226 if (other != NULL) {
4227 grow_to_match(other);
4228 // invariant: the finite support of mm2 is within mm->req()
4229 #ifdef ASSERT
4230 for (uint i = req(); i < other->req(); i++) {
4231 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
4232 }
4233 #endif
4234 }
4235 // Replace spurious copies of base_memory by top.
4236 Node* base_mem = base_memory();
4237 if (base_mem != NULL && !base_mem->is_top()) {
4238 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
4239 if (in(i) == base_mem)
4240 set_req(i, empty_memory());
4241 }
4242 }
4243 }
4244
4245 //---------------------------grow_to_match-------------------------------------
4246 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
4247 Node* empty_mem = empty_memory();
4248 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
4249 // look for the finite support of the other memory
4250 for (uint i = other->req(); --i >= req(); ) {
4251 if (other->in(i) != empty_mem) {
4252 uint new_len = i+1;
4253 while (req() < new_len) add_req(empty_mem);
4254 break;
4255 }
4256 }
4257 }
4258
4259 //---------------------------verify_sparse-------------------------------------
4260 #ifndef PRODUCT
4261 bool MergeMemNode::verify_sparse() const {
4262 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
4263 Node* base_mem = base_memory();
4264 // The following can happen in degenerate cases, since empty==top.
4265 if (is_empty_memory(base_mem)) return true;
4266 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4267 assert(in(i) != NULL, "sane slice");
4268 if (in(i) == base_mem) return false; // should have been the sentinel value!
4269 }
4270 return true;
4271 }
4272
4273 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
4274 Node* n;
4275 n = mm->in(idx);
4276 if (mem == n) return true; // might be empty_memory()
4277 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
4278 if (mem == n) return true;
4279 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) {
4280 if (mem == n) return true;
4281 if (n == NULL) break;
4282 }
4283 return false;
4284 }
4285 #endif // !PRODUCT