Thu, 24 May 2018 19:26:50 +0800
#7046 C2 supports long branch
Contributed-by: fujie
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.
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23 */
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"
42 // Portions of code courtesy of Clifford Click
44 // Optimization - Graph Style
46 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st);
48 //=============================================================================
49 uint MemNode::size_of() const { return sizeof(*this); }
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 }
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);
69 Compile* C = Compile::current();
70 if (C->alias_type(_adr_type)->is_volatile()) {
71 st->print(" Volatile!");
72 }
73 if (_unaligned_access) {
74 st->print(" unaligned");
75 }
76 if (_mismatched_access) {
77 st->print(" mismatched");
78 }
79 }
81 void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) {
82 st->print(" @");
83 if (adr_type == NULL) {
84 st->print("NULL");
85 } else {
86 adr_type->dump_on(st);
87 Compile* C = Compile::current();
88 Compile::AliasType* atp = NULL;
89 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type);
90 if (atp == NULL)
91 st->print(", idx=?\?;");
92 else if (atp->index() == Compile::AliasIdxBot)
93 st->print(", idx=Bot;");
94 else if (atp->index() == Compile::AliasIdxTop)
95 st->print(", idx=Top;");
96 else if (atp->index() == Compile::AliasIdxRaw)
97 st->print(", idx=Raw;");
98 else {
99 ciField* field = atp->field();
100 if (field) {
101 st->print(", name=");
102 field->print_name_on(st);
103 }
104 st->print(", idx=%d;", atp->index());
105 }
106 }
107 }
109 extern void print_alias_types();
111 #endif
113 Node *MemNode::optimize_simple_memory_chain(Node *mchain, const TypeOopPtr *t_oop, Node *load, PhaseGVN *phase) {
114 assert((t_oop != NULL), "sanity");
115 bool is_instance = t_oop->is_known_instance_field();
116 bool is_boxed_value_load = t_oop->is_ptr_to_boxed_value() &&
117 (load != NULL) && load->is_Load() &&
118 (phase->is_IterGVN() != NULL);
119 if (!(is_instance || is_boxed_value_load))
120 return mchain; // don't try to optimize non-instance types
121 uint instance_id = t_oop->instance_id();
122 Node *start_mem = phase->C->start()->proj_out(TypeFunc::Memory);
123 Node *prev = NULL;
124 Node *result = mchain;
125 while (prev != result) {
126 prev = result;
127 if (result == start_mem)
128 break; // hit one of our sentinels
129 // skip over a call which does not affect this memory slice
130 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {
131 Node *proj_in = result->in(0);
132 if (proj_in->is_Allocate() && proj_in->_idx == instance_id) {
133 break; // hit one of our sentinels
134 } else if (proj_in->is_Call()) {
135 CallNode *call = proj_in->as_Call();
136 if (!call->may_modify(t_oop, phase)) { // returns false for instances
137 result = call->in(TypeFunc::Memory);
138 }
139 } else if (proj_in->is_Initialize()) {
140 AllocateNode* alloc = proj_in->as_Initialize()->allocation();
141 // Stop if this is the initialization for the object instance which
142 // which contains this memory slice, otherwise skip over it.
143 if ((alloc == NULL) || (alloc->_idx == instance_id)) {
144 break;
145 }
146 if (is_instance) {
147 result = proj_in->in(TypeFunc::Memory);
148 } else if (is_boxed_value_load) {
149 Node* klass = alloc->in(AllocateNode::KlassNode);
150 const TypeKlassPtr* tklass = phase->type(klass)->is_klassptr();
151 if (tklass->klass_is_exact() && !tklass->klass()->equals(t_oop->klass())) {
152 result = proj_in->in(TypeFunc::Memory); // not related allocation
153 }
154 }
155 } else if (proj_in->is_MemBar()) {
156 result = proj_in->in(TypeFunc::Memory);
157 } else {
158 assert(false, "unexpected projection");
159 }
160 } else if (result->is_ClearArray()) {
161 if (!is_instance || !ClearArrayNode::step_through(&result, instance_id, phase)) {
162 // Can not bypass initialization of the instance
163 // we are looking for.
164 break;
165 }
166 // Otherwise skip it (the call updated 'result' value).
167 } else if (result->is_MergeMem()) {
168 result = step_through_mergemem(phase, result->as_MergeMem(), t_oop, NULL, tty);
169 }
170 }
171 return result;
172 }
174 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, Node *load, PhaseGVN *phase) {
175 const TypeOopPtr* t_oop = t_adr->isa_oopptr();
176 if (t_oop == NULL)
177 return mchain; // don't try to optimize non-oop types
178 Node* result = optimize_simple_memory_chain(mchain, t_oop, load, phase);
179 bool is_instance = t_oop->is_known_instance_field();
180 PhaseIterGVN *igvn = phase->is_IterGVN();
181 if (is_instance && igvn != NULL && result->is_Phi()) {
182 PhiNode *mphi = result->as_Phi();
183 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
184 const TypePtr *t = mphi->adr_type();
185 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
186 t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
187 t->is_oopptr()->cast_to_exactness(true)
188 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
189 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop) {
190 // clone the Phi with our address type
191 result = mphi->split_out_instance(t_adr, igvn);
192 } else {
193 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain");
194 }
195 }
196 return result;
197 }
199 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) {
200 uint alias_idx = phase->C->get_alias_index(tp);
201 Node *mem = mmem;
202 #ifdef ASSERT
203 {
204 // Check that current type is consistent with the alias index used during graph construction
205 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
206 bool consistent = adr_check == NULL || adr_check->empty() ||
207 phase->C->must_alias(adr_check, alias_idx );
208 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
209 if( !consistent && adr_check != NULL && !adr_check->empty() &&
210 tp->isa_aryptr() && tp->offset() == Type::OffsetBot &&
211 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot &&
212 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() ||
213 adr_check->offset() == oopDesc::klass_offset_in_bytes() ||
214 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) {
215 // don't assert if it is dead code.
216 consistent = true;
217 }
218 if( !consistent ) {
219 st->print("alias_idx==%d, adr_check==", alias_idx);
220 if( adr_check == NULL ) {
221 st->print("NULL");
222 } else {
223 adr_check->dump();
224 }
225 st->cr();
226 print_alias_types();
227 assert(consistent, "adr_check must match alias idx");
228 }
229 }
230 #endif
231 // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally
232 // means an array I have not precisely typed yet. Do not do any
233 // alias stuff with it any time soon.
234 const TypeOopPtr *toop = tp->isa_oopptr();
235 if( tp->base() != Type::AnyPtr &&
236 !(toop &&
237 toop->klass() != NULL &&
238 toop->klass()->is_java_lang_Object() &&
239 toop->offset() == Type::OffsetBot) ) {
240 // compress paths and change unreachable cycles to TOP
241 // If not, we can update the input infinitely along a MergeMem cycle
242 // Equivalent code in PhiNode::Ideal
243 Node* m = phase->transform(mmem);
244 // If transformed to a MergeMem, get the desired slice
245 // Otherwise the returned node represents memory for every slice
246 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
247 // Update input if it is progress over what we have now
248 }
249 return mem;
250 }
252 //--------------------------Ideal_common---------------------------------------
253 // Look for degenerate control and memory inputs. Bypass MergeMem inputs.
254 // Unhook non-raw memories from complete (macro-expanded) initializations.
255 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
256 // If our control input is a dead region, kill all below the region
257 Node *ctl = in(MemNode::Control);
258 if (ctl && remove_dead_region(phase, can_reshape))
259 return this;
260 ctl = in(MemNode::Control);
261 // Don't bother trying to transform a dead node
262 if (ctl && ctl->is_top()) return NodeSentinel;
264 PhaseIterGVN *igvn = phase->is_IterGVN();
265 // Wait if control on the worklist.
266 if (ctl && can_reshape && igvn != NULL) {
267 Node* bol = NULL;
268 Node* cmp = NULL;
269 if (ctl->in(0)->is_If()) {
270 assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity");
271 bol = ctl->in(0)->in(1);
272 if (bol->is_Bool())
273 cmp = ctl->in(0)->in(1)->in(1);
274 }
275 if (igvn->_worklist.member(ctl) ||
276 (bol != NULL && igvn->_worklist.member(bol)) ||
277 (cmp != NULL && igvn->_worklist.member(cmp)) ) {
278 // This control path may be dead.
279 // Delay this memory node transformation until the control is processed.
280 phase->is_IterGVN()->_worklist.push(this);
281 return NodeSentinel; // caller will return NULL
282 }
283 }
284 // Ignore if memory is dead, or self-loop
285 Node *mem = in(MemNode::Memory);
286 if (phase->type( mem ) == Type::TOP) return NodeSentinel; // caller will return NULL
287 assert(mem != this, "dead loop in MemNode::Ideal");
289 if (can_reshape && igvn != NULL && igvn->_worklist.member(mem)) {
290 // This memory slice may be dead.
291 // Delay this mem node transformation until the memory is processed.
292 phase->is_IterGVN()->_worklist.push(this);
293 return NodeSentinel; // caller will return NULL
294 }
296 Node *address = in(MemNode::Address);
297 const Type *t_adr = phase->type(address);
298 if (t_adr == Type::TOP) return NodeSentinel; // caller will return NULL
300 if (can_reshape && igvn != NULL &&
301 (igvn->_worklist.member(address) ||
302 igvn->_worklist.size() > 0 && (t_adr != adr_type())) ) {
303 // The address's base and type may change when the address is processed.
304 // Delay this mem node transformation until the address is processed.
305 phase->is_IterGVN()->_worklist.push(this);
306 return NodeSentinel; // caller will return NULL
307 }
309 // Do NOT remove or optimize the next lines: ensure a new alias index
310 // is allocated for an oop pointer type before Escape Analysis.
311 // Note: C++ will not remove it since the call has side effect.
312 if (t_adr->isa_oopptr()) {
313 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr());
314 }
316 Node* base = NULL;
317 if (address->is_AddP()) {
318 base = address->in(AddPNode::Base);
319 }
320 if (base != NULL && phase->type(base)->higher_equal(TypePtr::NULL_PTR) &&
321 !t_adr->isa_rawptr()) {
322 // Note: raw address has TOP base and top->higher_equal(TypePtr::NULL_PTR) is true.
323 // Skip this node optimization if its address has TOP base.
324 return NodeSentinel; // caller will return NULL
325 }
327 // Avoid independent memory operations
328 Node* old_mem = mem;
330 // The code which unhooks non-raw memories from complete (macro-expanded)
331 // initializations was removed. After macro-expansion all stores catched
332 // by Initialize node became raw stores and there is no information
333 // which memory slices they modify. So it is unsafe to move any memory
334 // operation above these stores. Also in most cases hooked non-raw memories
335 // were already unhooked by using information from detect_ptr_independence()
336 // and find_previous_store().
338 if (mem->is_MergeMem()) {
339 MergeMemNode* mmem = mem->as_MergeMem();
340 const TypePtr *tp = t_adr->is_ptr();
342 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
343 }
345 if (mem != old_mem) {
346 set_req(MemNode::Memory, mem);
347 if (can_reshape && old_mem->outcnt() == 0) {
348 igvn->_worklist.push(old_mem);
349 }
350 if (phase->type( mem ) == Type::TOP) return NodeSentinel;
351 return this;
352 }
354 // let the subclass continue analyzing...
355 return NULL;
356 }
358 // Helper function for proving some simple control dominations.
359 // Attempt to prove that all control inputs of 'dom' dominate 'sub'.
360 // Already assumes that 'dom' is available at 'sub', and that 'sub'
361 // is not a constant (dominated by the method's StartNode).
362 // Used by MemNode::find_previous_store to prove that the
363 // control input of a memory operation predates (dominates)
364 // an allocation it wants to look past.
365 bool MemNode::all_controls_dominate(Node* dom, Node* sub) {
366 if (dom == NULL || dom->is_top() || sub == NULL || sub->is_top())
367 return false; // Conservative answer for dead code
369 // Check 'dom'. Skip Proj and CatchProj nodes.
370 dom = dom->find_exact_control(dom);
371 if (dom == NULL || dom->is_top())
372 return false; // Conservative answer for dead code
374 if (dom == sub) {
375 // For the case when, for example, 'sub' is Initialize and the original
376 // 'dom' is Proj node of the 'sub'.
377 return false;
378 }
380 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub)
381 return true;
383 // 'dom' dominates 'sub' if its control edge and control edges
384 // of all its inputs dominate or equal to sub's control edge.
386 // Currently 'sub' is either Allocate, Initialize or Start nodes.
387 // Or Region for the check in LoadNode::Ideal();
388 // 'sub' should have sub->in(0) != NULL.
389 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() ||
390 sub->is_Region() || sub->is_Call(), "expecting only these nodes");
392 // Get control edge of 'sub'.
393 Node* orig_sub = sub;
394 sub = sub->find_exact_control(sub->in(0));
395 if (sub == NULL || sub->is_top())
396 return false; // Conservative answer for dead code
398 assert(sub->is_CFG(), "expecting control");
400 if (sub == dom)
401 return true;
403 if (sub->is_Start() || sub->is_Root())
404 return false;
406 {
407 // Check all control edges of 'dom'.
409 ResourceMark rm;
410 Arena* arena = Thread::current()->resource_area();
411 Node_List nlist(arena);
412 Unique_Node_List dom_list(arena);
414 dom_list.push(dom);
415 bool only_dominating_controls = false;
417 for (uint next = 0; next < dom_list.size(); next++) {
418 Node* n = dom_list.at(next);
419 if (n == orig_sub)
420 return false; // One of dom's inputs dominated by sub.
421 if (!n->is_CFG() && n->pinned()) {
422 // Check only own control edge for pinned non-control nodes.
423 n = n->find_exact_control(n->in(0));
424 if (n == NULL || n->is_top())
425 return false; // Conservative answer for dead code
426 assert(n->is_CFG(), "expecting control");
427 dom_list.push(n);
428 } else if (n->is_Con() || n->is_Start() || n->is_Root()) {
429 only_dominating_controls = true;
430 } else if (n->is_CFG()) {
431 if (n->dominates(sub, nlist))
432 only_dominating_controls = true;
433 else
434 return false;
435 } else {
436 // First, own control edge.
437 Node* m = n->find_exact_control(n->in(0));
438 if (m != NULL) {
439 if (m->is_top())
440 return false; // Conservative answer for dead code
441 dom_list.push(m);
442 }
443 // Now, the rest of edges.
444 uint cnt = n->req();
445 for (uint i = 1; i < cnt; i++) {
446 m = n->find_exact_control(n->in(i));
447 if (m == NULL || m->is_top())
448 continue;
449 dom_list.push(m);
450 }
451 }
452 }
453 return only_dominating_controls;
454 }
455 }
457 //---------------------detect_ptr_independence---------------------------------
458 // Used by MemNode::find_previous_store to prove that two base
459 // pointers are never equal.
460 // The pointers are accompanied by their associated allocations,
461 // if any, which have been previously discovered by the caller.
462 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
463 Node* p2, AllocateNode* a2,
464 PhaseTransform* phase) {
465 // Attempt to prove that these two pointers cannot be aliased.
466 // They may both manifestly be allocations, and they should differ.
467 // Or, if they are not both allocations, they can be distinct constants.
468 // Otherwise, one is an allocation and the other a pre-existing value.
469 if (a1 == NULL && a2 == NULL) { // neither an allocation
470 return (p1 != p2) && p1->is_Con() && p2->is_Con();
471 } else if (a1 != NULL && a2 != NULL) { // both allocations
472 return (a1 != a2);
473 } else if (a1 != NULL) { // one allocation a1
474 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.)
475 return all_controls_dominate(p2, a1);
476 } else { //(a2 != NULL) // one allocation a2
477 return all_controls_dominate(p1, a2);
478 }
479 return false;
480 }
483 // The logic for reordering loads and stores uses four steps:
484 // (a) Walk carefully past stores and initializations which we
485 // can prove are independent of this load.
486 // (b) Observe that the next memory state makes an exact match
487 // with self (load or store), and locate the relevant store.
488 // (c) Ensure that, if we were to wire self directly to the store,
489 // the optimizer would fold it up somehow.
490 // (d) Do the rewiring, and return, depending on some other part of
491 // the optimizer to fold up the load.
492 // This routine handles steps (a) and (b). Steps (c) and (d) are
493 // specific to loads and stores, so they are handled by the callers.
494 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.)
495 //
496 Node* MemNode::find_previous_store(PhaseTransform* phase) {
497 Node* ctrl = in(MemNode::Control);
498 Node* adr = in(MemNode::Address);
499 intptr_t offset = 0;
500 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
501 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase);
503 if (offset == Type::OffsetBot)
504 return NULL; // cannot unalias unless there are precise offsets
506 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr();
508 intptr_t size_in_bytes = memory_size();
510 Node* mem = in(MemNode::Memory); // start searching here...
512 int cnt = 50; // Cycle limiter
513 for (;;) { // While we can dance past unrelated stores...
514 if (--cnt < 0) break; // Caught in cycle or a complicated dance?
516 if (mem->is_Store()) {
517 Node* st_adr = mem->in(MemNode::Address);
518 intptr_t st_offset = 0;
519 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
520 if (st_base == NULL)
521 break; // inscrutable pointer
522 if (st_offset != offset && st_offset != Type::OffsetBot) {
523 const int MAX_STORE = BytesPerLong;
524 if (st_offset >= offset + size_in_bytes ||
525 st_offset <= offset - MAX_STORE ||
526 st_offset <= offset - mem->as_Store()->memory_size()) {
527 // Success: The offsets are provably independent.
528 // (You may ask, why not just test st_offset != offset and be done?
529 // The answer is that stores of different sizes can co-exist
530 // in the same sequence of RawMem effects. We sometimes initialize
531 // a whole 'tile' of array elements with a single jint or jlong.)
532 mem = mem->in(MemNode::Memory);
533 continue; // (a) advance through independent store memory
534 }
535 }
536 if (st_base != base &&
537 detect_ptr_independence(base, alloc,
538 st_base,
539 AllocateNode::Ideal_allocation(st_base, phase),
540 phase)) {
541 // Success: The bases are provably independent.
542 mem = mem->in(MemNode::Memory);
543 continue; // (a) advance through independent store memory
544 }
546 // (b) At this point, if the bases or offsets do not agree, we lose,
547 // since we have not managed to prove 'this' and 'mem' independent.
548 if (st_base == base && st_offset == offset) {
549 return mem; // let caller handle steps (c), (d)
550 }
552 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
553 InitializeNode* st_init = mem->in(0)->as_Initialize();
554 AllocateNode* st_alloc = st_init->allocation();
555 if (st_alloc == NULL)
556 break; // something degenerated
557 bool known_identical = false;
558 bool known_independent = false;
559 if (alloc == st_alloc)
560 known_identical = true;
561 else if (alloc != NULL)
562 known_independent = true;
563 else if (all_controls_dominate(this, st_alloc))
564 known_independent = true;
566 if (known_independent) {
567 // The bases are provably independent: Either they are
568 // manifestly distinct allocations, or else the control
569 // of this load dominates the store's allocation.
570 int alias_idx = phase->C->get_alias_index(adr_type());
571 if (alias_idx == Compile::AliasIdxRaw) {
572 mem = st_alloc->in(TypeFunc::Memory);
573 } else {
574 mem = st_init->memory(alias_idx);
575 }
576 continue; // (a) advance through independent store memory
577 }
579 // (b) at this point, if we are not looking at a store initializing
580 // the same allocation we are loading from, we lose.
581 if (known_identical) {
582 // From caller, can_see_stored_value will consult find_captured_store.
583 return mem; // let caller handle steps (c), (d)
584 }
586 } else if (addr_t != NULL && addr_t->is_known_instance_field()) {
587 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
588 if (mem->is_Proj() && mem->in(0)->is_Call()) {
589 CallNode *call = mem->in(0)->as_Call();
590 if (!call->may_modify(addr_t, phase)) {
591 mem = call->in(TypeFunc::Memory);
592 continue; // (a) advance through independent call memory
593 }
594 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) {
595 mem = mem->in(0)->in(TypeFunc::Memory);
596 continue; // (a) advance through independent MemBar memory
597 } else if (mem->is_ClearArray()) {
598 if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) {
599 // (the call updated 'mem' value)
600 continue; // (a) advance through independent allocation memory
601 } else {
602 // Can not bypass initialization of the instance
603 // we are looking for.
604 return mem;
605 }
606 } else if (mem->is_MergeMem()) {
607 int alias_idx = phase->C->get_alias_index(adr_type());
608 mem = mem->as_MergeMem()->memory_at(alias_idx);
609 continue; // (a) advance through independent MergeMem memory
610 }
611 }
613 // Unless there is an explicit 'continue', we must bail out here,
614 // because 'mem' is an inscrutable memory state (e.g., a call).
615 break;
616 }
618 return NULL; // bail out
619 }
621 //----------------------calculate_adr_type-------------------------------------
622 // Helper function. Notices when the given type of address hits top or bottom.
623 // Also, asserts a cross-check of the type against the expected address type.
624 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
625 if (t == Type::TOP) return NULL; // does not touch memory any more?
626 #ifdef PRODUCT
627 cross_check = NULL;
628 #else
629 if (!VerifyAliases || is_error_reported() || Node::in_dump()) cross_check = NULL;
630 #endif
631 const TypePtr* tp = t->isa_ptr();
632 if (tp == NULL) {
633 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
634 return TypePtr::BOTTOM; // touches lots of memory
635 } else {
636 #ifdef ASSERT
637 // %%%% [phh] We don't check the alias index if cross_check is
638 // TypeRawPtr::BOTTOM. Needs to be investigated.
639 if (cross_check != NULL &&
640 cross_check != TypePtr::BOTTOM &&
641 cross_check != TypeRawPtr::BOTTOM) {
642 // Recheck the alias index, to see if it has changed (due to a bug).
643 Compile* C = Compile::current();
644 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
645 "must stay in the original alias category");
646 // The type of the address must be contained in the adr_type,
647 // disregarding "null"-ness.
648 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
649 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
650 assert(cross_check->meet(tp_notnull) == cross_check->remove_speculative(),
651 "real address must not escape from expected memory type");
652 }
653 #endif
654 return tp;
655 }
656 }
658 //------------------------adr_phi_is_loop_invariant----------------------------
659 // A helper function for Ideal_DU_postCCP to check if a Phi in a counted
660 // loop is loop invariant. Make a quick traversal of Phi and associated
661 // CastPP nodes, looking to see if they are a closed group within the loop.
662 bool MemNode::adr_phi_is_loop_invariant(Node* adr_phi, Node* cast) {
663 // The idea is that the phi-nest must boil down to only CastPP nodes
664 // with the same data. This implies that any path into the loop already
665 // includes such a CastPP, and so the original cast, whatever its input,
666 // must be covered by an equivalent cast, with an earlier control input.
667 ResourceMark rm;
669 // The loop entry input of the phi should be the unique dominating
670 // node for every Phi/CastPP in the loop.
671 Unique_Node_List closure;
672 closure.push(adr_phi->in(LoopNode::EntryControl));
674 // Add the phi node and the cast to the worklist.
675 Unique_Node_List worklist;
676 worklist.push(adr_phi);
677 if( cast != NULL ){
678 if( !cast->is_ConstraintCast() ) return false;
679 worklist.push(cast);
680 }
682 // Begin recursive walk of phi nodes.
683 while( worklist.size() ){
684 // Take a node off the worklist
685 Node *n = worklist.pop();
686 if( !closure.member(n) ){
687 // Add it to the closure.
688 closure.push(n);
689 // Make a sanity check to ensure we don't waste too much time here.
690 if( closure.size() > 20) return false;
691 // This node is OK if:
692 // - it is a cast of an identical value
693 // - or it is a phi node (then we add its inputs to the worklist)
694 // Otherwise, the node is not OK, and we presume the cast is not invariant
695 if( n->is_ConstraintCast() ){
696 worklist.push(n->in(1));
697 } else if( n->is_Phi() ) {
698 for( uint i = 1; i < n->req(); i++ ) {
699 worklist.push(n->in(i));
700 }
701 } else {
702 return false;
703 }
704 }
705 }
707 // Quit when the worklist is empty, and we've found no offending nodes.
708 return true;
709 }
711 //------------------------------Ideal_DU_postCCP-------------------------------
712 // Find any cast-away of null-ness and keep its control. Null cast-aways are
713 // going away in this pass and we need to make this memory op depend on the
714 // gating null check.
715 Node *MemNode::Ideal_DU_postCCP( PhaseCCP *ccp ) {
716 return Ideal_common_DU_postCCP(ccp, this, in(MemNode::Address));
717 }
719 // I tried to leave the CastPP's in. This makes the graph more accurate in
720 // some sense; we get to keep around the knowledge that an oop is not-null
721 // after some test. Alas, the CastPP's interfere with GVN (some values are
722 // the regular oop, some are the CastPP of the oop, all merge at Phi's which
723 // cannot collapse, etc). This cost us 10% on SpecJVM, even when I removed
724 // some of the more trivial cases in the optimizer. Removing more useless
725 // Phi's started allowing Loads to illegally float above null checks. I gave
726 // up on this approach. CNC 10/20/2000
727 // This static method may be called not from MemNode (EncodePNode calls it).
728 // Only the control edge of the node 'n' might be updated.
729 Node *MemNode::Ideal_common_DU_postCCP( PhaseCCP *ccp, Node* n, Node* adr ) {
730 Node *skipped_cast = NULL;
731 // Need a null check? Regular static accesses do not because they are
732 // from constant addresses. Array ops are gated by the range check (which
733 // always includes a NULL check). Just check field ops.
734 if( n->in(MemNode::Control) == NULL ) {
735 // Scan upwards for the highest location we can place this memory op.
736 while( true ) {
737 switch( adr->Opcode() ) {
739 case Op_AddP: // No change to NULL-ness, so peek thru AddP's
740 adr = adr->in(AddPNode::Base);
741 continue;
743 case Op_DecodeN: // No change to NULL-ness, so peek thru
744 case Op_DecodeNKlass:
745 adr = adr->in(1);
746 continue;
748 case Op_EncodeP:
749 case Op_EncodePKlass:
750 // EncodeP node's control edge could be set by this method
751 // when EncodeP node depends on CastPP node.
752 //
753 // Use its control edge for memory op because EncodeP may go away
754 // later when it is folded with following or preceding DecodeN node.
755 if (adr->in(0) == NULL) {
756 // Keep looking for cast nodes.
757 adr = adr->in(1);
758 continue;
759 }
760 ccp->hash_delete(n);
761 n->set_req(MemNode::Control, adr->in(0));
762 ccp->hash_insert(n);
763 return n;
765 case Op_CastPP:
766 // If the CastPP is useless, just peek on through it.
767 if( ccp->type(adr) == ccp->type(adr->in(1)) ) {
768 // Remember the cast that we've peeked though. If we peek
769 // through more than one, then we end up remembering the highest
770 // one, that is, if in a loop, the one closest to the top.
771 skipped_cast = adr;
772 adr = adr->in(1);
773 continue;
774 }
775 // CastPP is going away in this pass! We need this memory op to be
776 // control-dependent on the test that is guarding the CastPP.
777 ccp->hash_delete(n);
778 n->set_req(MemNode::Control, adr->in(0));
779 ccp->hash_insert(n);
780 return n;
782 case Op_Phi:
783 // Attempt to float above a Phi to some dominating point.
784 if (adr->in(0) != NULL && adr->in(0)->is_CountedLoop()) {
785 // If we've already peeked through a Cast (which could have set the
786 // control), we can't float above a Phi, because the skipped Cast
787 // may not be loop invariant.
788 if (adr_phi_is_loop_invariant(adr, skipped_cast)) {
789 adr = adr->in(1);
790 continue;
791 }
792 }
794 // Intentional fallthrough!
796 // No obvious dominating point. The mem op is pinned below the Phi
797 // by the Phi itself. If the Phi goes away (no true value is merged)
798 // then the mem op can float, but not indefinitely. It must be pinned
799 // behind the controls leading to the Phi.
800 case Op_CheckCastPP:
801 // These usually stick around to change address type, however a
802 // useless one can be elided and we still need to pick up a control edge
803 if (adr->in(0) == NULL) {
804 // This CheckCastPP node has NO control and is likely useless. But we
805 // need check further up the ancestor chain for a control input to keep
806 // the node in place. 4959717.
807 skipped_cast = adr;
808 adr = adr->in(1);
809 continue;
810 }
811 ccp->hash_delete(n);
812 n->set_req(MemNode::Control, adr->in(0));
813 ccp->hash_insert(n);
814 return n;
816 // List of "safe" opcodes; those that implicitly block the memory
817 // op below any null check.
818 case Op_CastX2P: // no null checks on native pointers
819 case Op_Parm: // 'this' pointer is not null
820 case Op_LoadP: // Loading from within a klass
821 case Op_LoadN: // Loading from within a klass
822 case Op_LoadKlass: // Loading from within a klass
823 case Op_LoadNKlass: // Loading from within a klass
824 case Op_ConP: // Loading from a klass
825 case Op_ConN: // Loading from a klass
826 case Op_ConNKlass: // Loading from a klass
827 case Op_CreateEx: // Sucking up the guts of an exception oop
828 case Op_Con: // Reading from TLS
829 case Op_CMoveP: // CMoveP is pinned
830 case Op_CMoveN: // CMoveN is pinned
831 break; // No progress
833 case Op_Proj: // Direct call to an allocation routine
834 case Op_SCMemProj: // Memory state from store conditional ops
835 #ifdef ASSERT
836 {
837 assert(adr->as_Proj()->_con == TypeFunc::Parms, "must be return value");
838 const Node* call = adr->in(0);
839 if (call->is_CallJava()) {
840 const CallJavaNode* call_java = call->as_CallJava();
841 const TypeTuple *r = call_java->tf()->range();
842 assert(r->cnt() > TypeFunc::Parms, "must return value");
843 const Type* ret_type = r->field_at(TypeFunc::Parms);
844 assert(ret_type && ret_type->isa_ptr(), "must return pointer");
845 // We further presume that this is one of
846 // new_instance_Java, new_array_Java, or
847 // the like, but do not assert for this.
848 } else if (call->is_Allocate()) {
849 // similar case to new_instance_Java, etc.
850 } else if (!call->is_CallLeaf()) {
851 // Projections from fetch_oop (OSR) are allowed as well.
852 ShouldNotReachHere();
853 }
854 }
855 #endif
856 break;
857 default:
858 ShouldNotReachHere();
859 }
860 break;
861 }
862 }
864 return NULL; // No progress
865 }
868 //=============================================================================
869 // Should LoadNode::Ideal() attempt to remove control edges?
870 bool LoadNode::can_remove_control() const {
871 return true;
872 }
873 uint LoadNode::size_of() const { return sizeof(*this); }
874 uint LoadNode::cmp( const Node &n ) const
875 { return !Type::cmp( _type, ((LoadNode&)n)._type ); }
876 const Type *LoadNode::bottom_type() const { return _type; }
877 uint LoadNode::ideal_reg() const {
878 return _type->ideal_reg();
879 }
881 #ifndef PRODUCT
882 void LoadNode::dump_spec(outputStream *st) const {
883 MemNode::dump_spec(st);
884 if( !Verbose && !WizardMode ) {
885 // standard dump does this in Verbose and WizardMode
886 st->print(" #"); _type->dump_on(st);
887 }
888 if (!_depends_only_on_test) {
889 st->print(" (does not depend only on test)");
890 }
891 }
892 #endif
894 #ifdef ASSERT
895 //----------------------------is_immutable_value-------------------------------
896 // Helper function to allow a raw load without control edge for some cases
897 bool LoadNode::is_immutable_value(Node* adr) {
898 return (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() &&
899 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal &&
900 (adr->in(AddPNode::Offset)->find_intptr_t_con(-1) ==
901 in_bytes(JavaThread::osthread_offset())));
902 }
903 #endif
905 //----------------------------LoadNode::make-----------------------------------
906 // Polymorphic factory method:
907 Node *LoadNode::make(PhaseGVN& gvn, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt, MemOrd mo, ControlDependency control_dependency) {
908 Compile* C = gvn.C;
910 // sanity check the alias category against the created node type
911 assert(!(adr_type->isa_oopptr() &&
912 adr_type->offset() == oopDesc::klass_offset_in_bytes()),
913 "use LoadKlassNode instead");
914 assert(!(adr_type->isa_aryptr() &&
915 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
916 "use LoadRangeNode instead");
917 // Check control edge of raw loads
918 assert( ctl != NULL || C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
919 // oop will be recorded in oop map if load crosses safepoint
920 rt->isa_oopptr() || is_immutable_value(adr),
921 "raw memory operations should have control edge");
922 switch (bt) {
923 case T_BOOLEAN: return new (C) LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency);
924 case T_BYTE: return new (C) LoadBNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency);
925 case T_INT: return new (C) LoadINode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency);
926 case T_CHAR: return new (C) LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency);
927 case T_SHORT: return new (C) LoadSNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency);
928 case T_LONG: return new (C) LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency);
929 case T_FLOAT: return new (C) LoadFNode (ctl, mem, adr, adr_type, rt, mo, control_dependency);
930 case T_DOUBLE: return new (C) LoadDNode (ctl, mem, adr, adr_type, rt, mo, control_dependency);
931 case T_ADDRESS: return new (C) LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency);
932 case T_OBJECT:
933 #ifdef _LP64
934 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
935 Node* load = gvn.transform(new (C) LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo, control_dependency));
936 return new (C) DecodeNNode(load, load->bottom_type()->make_ptr());
937 } else
938 #endif
939 {
940 assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop");
941 return new (C) LoadPNode(ctl, mem, adr, adr_type, rt->is_oopptr(), mo, control_dependency);
942 }
943 }
944 ShouldNotReachHere();
945 return (LoadNode*)NULL;
946 }
948 LoadLNode* LoadLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo, ControlDependency control_dependency) {
949 bool require_atomic = true;
950 return new (C) LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency, require_atomic);
951 }
953 LoadDNode* LoadDNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo, ControlDependency control_dependency) {
954 bool require_atomic = true;
955 return new (C) LoadDNode(ctl, mem, adr, adr_type, rt, mo, control_dependency, require_atomic);
956 }
960 //------------------------------hash-------------------------------------------
961 uint LoadNode::hash() const {
962 // unroll addition of interesting fields
963 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
964 }
966 static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) {
967 if ((atp != NULL) && (atp->index() >= Compile::AliasIdxRaw)) {
968 bool non_volatile = (atp->field() != NULL) && !atp->field()->is_volatile();
969 bool is_stable_ary = FoldStableValues &&
970 (tp != NULL) && (tp->isa_aryptr() != NULL) &&
971 tp->isa_aryptr()->is_stable();
973 return (eliminate_boxing && non_volatile) || is_stable_ary;
974 }
976 return false;
977 }
979 //---------------------------can_see_stored_value------------------------------
980 // This routine exists to make sure this set of tests is done the same
981 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
982 // will change the graph shape in a way which makes memory alive twice at the
983 // same time (uses the Oracle model of aliasing), then some
984 // LoadXNode::Identity will fold things back to the equivalence-class model
985 // of aliasing.
986 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const {
987 Node* ld_adr = in(MemNode::Address);
988 intptr_t ld_off = 0;
989 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
990 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
991 Compile::AliasType* atp = (tp != NULL) ? phase->C->alias_type(tp) : NULL;
992 // This is more general than load from boxing objects.
993 if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) {
994 uint alias_idx = atp->index();
995 bool final = !atp->is_rewritable();
996 Node* result = NULL;
997 Node* current = st;
998 // Skip through chains of MemBarNodes checking the MergeMems for
999 // new states for the slice of this load. Stop once any other
1000 // kind of node is encountered. Loads from final memory can skip
1001 // through any kind of MemBar but normal loads shouldn't skip
1002 // through MemBarAcquire since the could allow them to move out of
1003 // a synchronized region.
1004 while (current->is_Proj()) {
1005 int opc = current->in(0)->Opcode();
1006 if ((final && (opc == Op_MemBarAcquire ||
1007 opc == Op_MemBarAcquireLock ||
1008 opc == Op_LoadFence)) ||
1009 opc == Op_MemBarRelease ||
1010 opc == Op_StoreFence ||
1011 opc == Op_MemBarReleaseLock ||
1012 opc == Op_MemBarCPUOrder) {
1013 Node* mem = current->in(0)->in(TypeFunc::Memory);
1014 if (mem->is_MergeMem()) {
1015 MergeMemNode* merge = mem->as_MergeMem();
1016 Node* new_st = merge->memory_at(alias_idx);
1017 if (new_st == merge->base_memory()) {
1018 // Keep searching
1019 current = new_st;
1020 continue;
1021 }
1022 // Save the new memory state for the slice and fall through
1023 // to exit.
1024 result = new_st;
1025 }
1026 }
1027 break;
1028 }
1029 if (result != NULL) {
1030 st = result;
1031 }
1032 }
1034 // Loop around twice in the case Load -> Initialize -> Store.
1035 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
1036 for (int trip = 0; trip <= 1; trip++) {
1038 if (st->is_Store()) {
1039 Node* st_adr = st->in(MemNode::Address);
1040 if (!phase->eqv(st_adr, ld_adr)) {
1041 // Try harder before giving up... Match raw and non-raw pointers.
1042 intptr_t st_off = 0;
1043 AllocateNode* alloc = AllocateNode::Ideal_allocation(st_adr, phase, st_off);
1044 if (alloc == NULL) return NULL;
1045 if (alloc != ld_alloc) return NULL;
1046 if (ld_off != st_off) return NULL;
1047 // At this point we have proven something like this setup:
1048 // A = Allocate(...)
1049 // L = LoadQ(, AddP(CastPP(, A.Parm),, #Off))
1050 // S = StoreQ(, AddP(, A.Parm , #Off), V)
1051 // (Actually, we haven't yet proven the Q's are the same.)
1052 // In other words, we are loading from a casted version of
1053 // the same pointer-and-offset that we stored to.
1054 // Thus, we are able to replace L by V.
1055 }
1056 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
1057 if (store_Opcode() != st->Opcode())
1058 return NULL;
1059 return st->in(MemNode::ValueIn);
1060 }
1062 // A load from a freshly-created object always returns zero.
1063 // (This can happen after LoadNode::Ideal resets the load's memory input
1064 // to find_captured_store, which returned InitializeNode::zero_memory.)
1065 if (st->is_Proj() && st->in(0)->is_Allocate() &&
1066 (st->in(0) == ld_alloc) &&
1067 (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) {
1068 // return a zero value for the load's basic type
1069 // (This is one of the few places where a generic PhaseTransform
1070 // can create new nodes. Think of it as lazily manifesting
1071 // virtually pre-existing constants.)
1072 return phase->zerocon(memory_type());
1073 }
1075 // A load from an initialization barrier can match a captured store.
1076 if (st->is_Proj() && st->in(0)->is_Initialize()) {
1077 InitializeNode* init = st->in(0)->as_Initialize();
1078 AllocateNode* alloc = init->allocation();
1079 if ((alloc != NULL) && (alloc == ld_alloc)) {
1080 // examine a captured store value
1081 st = init->find_captured_store(ld_off, memory_size(), phase);
1082 if (st != NULL)
1083 continue; // take one more trip around
1084 }
1085 }
1087 // Load boxed value from result of valueOf() call is input parameter.
1088 if (this->is_Load() && ld_adr->is_AddP() &&
1089 (tp != NULL) && tp->is_ptr_to_boxed_value()) {
1090 intptr_t ignore = 0;
1091 Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore);
1092 if (base != NULL && base->is_Proj() &&
1093 base->as_Proj()->_con == TypeFunc::Parms &&
1094 base->in(0)->is_CallStaticJava() &&
1095 base->in(0)->as_CallStaticJava()->is_boxing_method()) {
1096 return base->in(0)->in(TypeFunc::Parms);
1097 }
1098 }
1100 break;
1101 }
1103 return NULL;
1104 }
1106 //----------------------is_instance_field_load_with_local_phi------------------
1107 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
1108 if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl &&
1109 in(Address)->is_AddP() ) {
1110 const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr();
1111 // Only instances and boxed values.
1112 if( t_oop != NULL &&
1113 (t_oop->is_ptr_to_boxed_value() ||
1114 t_oop->is_known_instance_field()) &&
1115 t_oop->offset() != Type::OffsetBot &&
1116 t_oop->offset() != Type::OffsetTop) {
1117 return true;
1118 }
1119 }
1120 return false;
1121 }
1123 //------------------------------Identity---------------------------------------
1124 // Loads are identity if previous store is to same address
1125 Node *LoadNode::Identity( PhaseTransform *phase ) {
1126 // If the previous store-maker is the right kind of Store, and the store is
1127 // to the same address, then we are equal to the value stored.
1128 Node* mem = in(Memory);
1129 Node* value = can_see_stored_value(mem, phase);
1130 if( value ) {
1131 // byte, short & char stores truncate naturally.
1132 // A load has to load the truncated value which requires
1133 // some sort of masking operation and that requires an
1134 // Ideal call instead of an Identity call.
1135 if (memory_size() < BytesPerInt) {
1136 // If the input to the store does not fit with the load's result type,
1137 // it must be truncated via an Ideal call.
1138 if (!phase->type(value)->higher_equal(phase->type(this)))
1139 return this;
1140 }
1141 // (This works even when value is a Con, but LoadNode::Value
1142 // usually runs first, producing the singleton type of the Con.)
1143 return value;
1144 }
1146 // Search for an existing data phi which was generated before for the same
1147 // instance's field to avoid infinite generation of phis in a loop.
1148 Node *region = mem->in(0);
1149 if (is_instance_field_load_with_local_phi(region)) {
1150 const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr();
1151 int this_index = phase->C->get_alias_index(addr_t);
1152 int this_offset = addr_t->offset();
1153 int this_iid = addr_t->instance_id();
1154 if (!addr_t->is_known_instance() &&
1155 addr_t->is_ptr_to_boxed_value()) {
1156 // Use _idx of address base (could be Phi node) for boxed values.
1157 intptr_t ignore = 0;
1158 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1159 if (base == NULL) {
1160 return this;
1161 }
1162 this_iid = base->_idx;
1163 }
1164 const Type* this_type = bottom_type();
1165 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1166 Node* phi = region->fast_out(i);
1167 if (phi->is_Phi() && phi != mem &&
1168 phi->as_Phi()->is_same_inst_field(this_type, (int)mem->_idx, this_iid, this_index, this_offset)) {
1169 return phi;
1170 }
1171 }
1172 }
1174 return this;
1175 }
1177 // We're loading from an object which has autobox behaviour.
1178 // If this object is result of a valueOf call we'll have a phi
1179 // merging a newly allocated object and a load from the cache.
1180 // We want to replace this load with the original incoming
1181 // argument to the valueOf call.
1182 Node* LoadNode::eliminate_autobox(PhaseGVN* phase) {
1183 assert(phase->C->eliminate_boxing(), "sanity");
1184 intptr_t ignore = 0;
1185 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1186 if ((base == NULL) || base->is_Phi()) {
1187 // Push the loads from the phi that comes from valueOf up
1188 // through it to allow elimination of the loads and the recovery
1189 // of the original value. It is done in split_through_phi().
1190 return NULL;
1191 } else if (base->is_Load() ||
1192 base->is_DecodeN() && base->in(1)->is_Load()) {
1193 // Eliminate the load of boxed value for integer types from the cache
1194 // array by deriving the value from the index into the array.
1195 // Capture the offset of the load and then reverse the computation.
1197 // Get LoadN node which loads a boxing object from 'cache' array.
1198 if (base->is_DecodeN()) {
1199 base = base->in(1);
1200 }
1201 if (!base->in(Address)->is_AddP()) {
1202 return NULL; // Complex address
1203 }
1204 AddPNode* address = base->in(Address)->as_AddP();
1205 Node* cache_base = address->in(AddPNode::Base);
1206 if ((cache_base != NULL) && cache_base->is_DecodeN()) {
1207 // Get ConP node which is static 'cache' field.
1208 cache_base = cache_base->in(1);
1209 }
1210 if ((cache_base != NULL) && cache_base->is_Con()) {
1211 const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr();
1212 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1213 Node* elements[4];
1214 int shift = exact_log2(type2aelembytes(T_OBJECT));
1215 int count = address->unpack_offsets(elements, ARRAY_SIZE(elements));
1216 if ((count > 0) && elements[0]->is_Con() &&
1217 ((count == 1) ||
1218 (count == 2) && elements[1]->Opcode() == Op_LShiftX &&
1219 elements[1]->in(2) == phase->intcon(shift))) {
1220 ciObjArray* array = base_type->const_oop()->as_obj_array();
1221 // Fetch the box object cache[0] at the base of the array and get its value
1222 ciInstance* box = array->obj_at(0)->as_instance();
1223 ciInstanceKlass* ik = box->klass()->as_instance_klass();
1224 assert(ik->is_box_klass(), "sanity");
1225 assert(ik->nof_nonstatic_fields() == 1, "change following code");
1226 if (ik->nof_nonstatic_fields() == 1) {
1227 // This should be true nonstatic_field_at requires calling
1228 // nof_nonstatic_fields so check it anyway
1229 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1230 BasicType bt = c.basic_type();
1231 // Only integer types have boxing cache.
1232 assert(bt == T_BOOLEAN || bt == T_CHAR ||
1233 bt == T_BYTE || bt == T_SHORT ||
1234 bt == T_INT || bt == T_LONG, err_msg_res("wrong type = %s", type2name(bt)));
1235 jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int();
1236 if (cache_low != (int)cache_low) {
1237 return NULL; // should not happen since cache is array indexed by value
1238 }
1239 jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift);
1240 if (offset != (int)offset) {
1241 return NULL; // should not happen since cache is array indexed by value
1242 }
1243 // Add up all the offsets making of the address of the load
1244 Node* result = elements[0];
1245 for (int i = 1; i < count; i++) {
1246 result = phase->transform(new (phase->C) AddXNode(result, elements[i]));
1247 }
1248 // Remove the constant offset from the address and then
1249 result = phase->transform(new (phase->C) AddXNode(result, phase->MakeConX(-(int)offset)));
1250 // remove the scaling of the offset to recover the original index.
1251 if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) {
1252 // Peel the shift off directly but wrap it in a dummy node
1253 // since Ideal can't return existing nodes
1254 result = new (phase->C) RShiftXNode(result->in(1), phase->intcon(0));
1255 } else if (result->is_Add() && result->in(2)->is_Con() &&
1256 result->in(1)->Opcode() == Op_LShiftX &&
1257 result->in(1)->in(2) == phase->intcon(shift)) {
1258 // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z)
1259 // but for boxing cache access we know that X<<Z will not overflow
1260 // (there is range check) so we do this optimizatrion by hand here.
1261 Node* add_con = new (phase->C) RShiftXNode(result->in(2), phase->intcon(shift));
1262 result = new (phase->C) AddXNode(result->in(1)->in(1), phase->transform(add_con));
1263 } else {
1264 result = new (phase->C) RShiftXNode(result, phase->intcon(shift));
1265 }
1266 #ifdef _LP64
1267 if (bt != T_LONG) {
1268 result = new (phase->C) ConvL2INode(phase->transform(result));
1269 }
1270 #else
1271 if (bt == T_LONG) {
1272 result = new (phase->C) ConvI2LNode(phase->transform(result));
1273 }
1274 #endif
1275 // Boxing/unboxing can be done from signed & unsigned loads (e.g. LoadUB -> ... -> LoadB pair).
1276 // Need to preserve unboxing load type if it is unsigned.
1277 switch(this->Opcode()) {
1278 case Op_LoadUB:
1279 result = new (phase->C) AndINode(phase->transform(result), phase->intcon(0xFF));
1280 break;
1281 case Op_LoadUS:
1282 result = new (phase->C) AndINode(phase->transform(result), phase->intcon(0xFFFF));
1283 break;
1284 }
1285 return result;
1286 }
1287 }
1288 }
1289 }
1290 }
1291 return NULL;
1292 }
1294 static bool stable_phi(PhiNode* phi, PhaseGVN *phase) {
1295 Node* region = phi->in(0);
1296 if (region == NULL) {
1297 return false; // Wait stable graph
1298 }
1299 uint cnt = phi->req();
1300 for (uint i = 1; i < cnt; i++) {
1301 Node* rc = region->in(i);
1302 if (rc == NULL || phase->type(rc) == Type::TOP)
1303 return false; // Wait stable graph
1304 Node* in = phi->in(i);
1305 if (in == NULL || phase->type(in) == Type::TOP)
1306 return false; // Wait stable graph
1307 }
1308 return true;
1309 }
1310 //------------------------------split_through_phi------------------------------
1311 // Split instance or boxed field load through Phi.
1312 Node *LoadNode::split_through_phi(PhaseGVN *phase) {
1313 Node* mem = in(Memory);
1314 Node* address = in(Address);
1315 const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr();
1317 assert((t_oop != NULL) &&
1318 (t_oop->is_known_instance_field() ||
1319 t_oop->is_ptr_to_boxed_value()), "invalide conditions");
1321 Compile* C = phase->C;
1322 intptr_t ignore = 0;
1323 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1324 bool base_is_phi = (base != NULL) && base->is_Phi();
1325 bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() &&
1326 (base != NULL) && (base == address->in(AddPNode::Base)) &&
1327 phase->type(base)->higher_equal(TypePtr::NOTNULL);
1329 if (!((mem->is_Phi() || base_is_phi) &&
1330 (load_boxed_values || t_oop->is_known_instance_field()))) {
1331 return NULL; // memory is not Phi
1332 }
1334 if (mem->is_Phi()) {
1335 if (!stable_phi(mem->as_Phi(), phase)) {
1336 return NULL; // Wait stable graph
1337 }
1338 uint cnt = mem->req();
1339 // Check for loop invariant memory.
1340 if (cnt == 3) {
1341 for (uint i = 1; i < cnt; i++) {
1342 Node* in = mem->in(i);
1343 Node* m = optimize_memory_chain(in, t_oop, this, phase);
1344 if (m == mem) {
1345 set_req(Memory, mem->in(cnt - i));
1346 return this; // made change
1347 }
1348 }
1349 }
1350 }
1351 if (base_is_phi) {
1352 if (!stable_phi(base->as_Phi(), phase)) {
1353 return NULL; // Wait stable graph
1354 }
1355 uint cnt = base->req();
1356 // Check for loop invariant memory.
1357 if (cnt == 3) {
1358 for (uint i = 1; i < cnt; i++) {
1359 if (base->in(i) == base) {
1360 return NULL; // Wait stable graph
1361 }
1362 }
1363 }
1364 }
1366 bool load_boxed_phi = load_boxed_values && base_is_phi && (base->in(0) == mem->in(0));
1368 // Split through Phi (see original code in loopopts.cpp).
1369 assert(C->have_alias_type(t_oop), "instance should have alias type");
1371 // Do nothing here if Identity will find a value
1372 // (to avoid infinite chain of value phis generation).
1373 if (!phase->eqv(this, this->Identity(phase)))
1374 return NULL;
1376 // Select Region to split through.
1377 Node* region;
1378 if (!base_is_phi) {
1379 assert(mem->is_Phi(), "sanity");
1380 region = mem->in(0);
1381 // Skip if the region dominates some control edge of the address.
1382 if (!MemNode::all_controls_dominate(address, region))
1383 return NULL;
1384 } else if (!mem->is_Phi()) {
1385 assert(base_is_phi, "sanity");
1386 region = base->in(0);
1387 // Skip if the region dominates some control edge of the memory.
1388 if (!MemNode::all_controls_dominate(mem, region))
1389 return NULL;
1390 } else if (base->in(0) != mem->in(0)) {
1391 assert(base_is_phi && mem->is_Phi(), "sanity");
1392 if (MemNode::all_controls_dominate(mem, base->in(0))) {
1393 region = base->in(0);
1394 } else if (MemNode::all_controls_dominate(address, mem->in(0))) {
1395 region = mem->in(0);
1396 } else {
1397 return NULL; // complex graph
1398 }
1399 } else {
1400 assert(base->in(0) == mem->in(0), "sanity");
1401 region = mem->in(0);
1402 }
1404 const Type* this_type = this->bottom_type();
1405 int this_index = C->get_alias_index(t_oop);
1406 int this_offset = t_oop->offset();
1407 int this_iid = t_oop->instance_id();
1408 if (!t_oop->is_known_instance() && load_boxed_values) {
1409 // Use _idx of address base for boxed values.
1410 this_iid = base->_idx;
1411 }
1412 PhaseIterGVN* igvn = phase->is_IterGVN();
1413 Node* phi = new (C) PhiNode(region, this_type, NULL, mem->_idx, this_iid, this_index, this_offset);
1414 for (uint i = 1; i < region->req(); i++) {
1415 Node* x;
1416 Node* the_clone = NULL;
1417 if (region->in(i) == C->top()) {
1418 x = C->top(); // Dead path? Use a dead data op
1419 } else {
1420 x = this->clone(); // Else clone up the data op
1421 the_clone = x; // Remember for possible deletion.
1422 // Alter data node to use pre-phi inputs
1423 if (this->in(0) == region) {
1424 x->set_req(0, region->in(i));
1425 } else {
1426 x->set_req(0, NULL);
1427 }
1428 if (mem->is_Phi() && (mem->in(0) == region)) {
1429 x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone.
1430 }
1431 if (address->is_Phi() && address->in(0) == region) {
1432 x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone
1433 }
1434 if (base_is_phi && (base->in(0) == region)) {
1435 Node* base_x = base->in(i); // Clone address for loads from boxed objects.
1436 Node* adr_x = phase->transform(new (C) AddPNode(base_x,base_x,address->in(AddPNode::Offset)));
1437 x->set_req(Address, adr_x);
1438 }
1439 }
1440 // Check for a 'win' on some paths
1441 const Type *t = x->Value(igvn);
1443 bool singleton = t->singleton();
1445 // See comments in PhaseIdealLoop::split_thru_phi().
1446 if (singleton && t == Type::TOP) {
1447 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1448 }
1450 if (singleton) {
1451 x = igvn->makecon(t);
1452 } else {
1453 // We now call Identity to try to simplify the cloned node.
1454 // Note that some Identity methods call phase->type(this).
1455 // Make sure that the type array is big enough for
1456 // our new node, even though we may throw the node away.
1457 // (This tweaking with igvn only works because x is a new node.)
1458 igvn->set_type(x, t);
1459 // If x is a TypeNode, capture any more-precise type permanently into Node
1460 // otherwise it will be not updated during igvn->transform since
1461 // igvn->type(x) is set to x->Value() already.
1462 x->raise_bottom_type(t);
1463 Node *y = x->Identity(igvn);
1464 if (y != x) {
1465 x = y;
1466 } else {
1467 y = igvn->hash_find_insert(x);
1468 if (y) {
1469 x = y;
1470 } else {
1471 // Else x is a new node we are keeping
1472 // We do not need register_new_node_with_optimizer
1473 // because set_type has already been called.
1474 igvn->_worklist.push(x);
1475 }
1476 }
1477 }
1478 if (x != the_clone && the_clone != NULL) {
1479 igvn->remove_dead_node(the_clone);
1480 }
1481 phi->set_req(i, x);
1482 }
1483 // Record Phi
1484 igvn->register_new_node_with_optimizer(phi);
1485 return phi;
1486 }
1488 //------------------------------Ideal------------------------------------------
1489 // If the load is from Field memory and the pointer is non-null, it might be possible to
1490 // zero out the control input.
1491 // If the offset is constant and the base is an object allocation,
1492 // try to hook me up to the exact initializing store.
1493 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1494 Node* p = MemNode::Ideal_common(phase, can_reshape);
1495 if (p) return (p == NodeSentinel) ? NULL : p;
1497 Node* ctrl = in(MemNode::Control);
1498 Node* address = in(MemNode::Address);
1500 // Skip up past a SafePoint control. Cannot do this for Stores because
1501 // pointer stores & cardmarks must stay on the same side of a SafePoint.
1502 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint &&
1503 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw ) {
1504 ctrl = ctrl->in(0);
1505 set_req(MemNode::Control,ctrl);
1506 }
1508 intptr_t ignore = 0;
1509 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1510 if (base != NULL
1511 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
1512 // Check for useless control edge in some common special cases
1513 if (in(MemNode::Control) != NULL
1514 && can_remove_control()
1515 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1516 && all_controls_dominate(base, phase->C->start())) {
1517 // A method-invariant, non-null address (constant or 'this' argument).
1518 set_req(MemNode::Control, NULL);
1519 }
1520 }
1522 Node* mem = in(MemNode::Memory);
1523 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1525 if (can_reshape && (addr_t != NULL)) {
1526 // try to optimize our memory input
1527 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase);
1528 if (opt_mem != mem) {
1529 set_req(MemNode::Memory, opt_mem);
1530 if (phase->type( opt_mem ) == Type::TOP) return NULL;
1531 return this;
1532 }
1533 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1534 if ((t_oop != NULL) &&
1535 (t_oop->is_known_instance_field() ||
1536 t_oop->is_ptr_to_boxed_value())) {
1537 PhaseIterGVN *igvn = phase->is_IterGVN();
1538 if (igvn != NULL && igvn->_worklist.member(opt_mem)) {
1539 // Delay this transformation until memory Phi is processed.
1540 phase->is_IterGVN()->_worklist.push(this);
1541 return NULL;
1542 }
1543 // Split instance field load through Phi.
1544 Node* result = split_through_phi(phase);
1545 if (result != NULL) return result;
1547 if (t_oop->is_ptr_to_boxed_value()) {
1548 Node* result = eliminate_autobox(phase);
1549 if (result != NULL) return result;
1550 }
1551 }
1552 }
1554 // Check for prior store with a different base or offset; make Load
1555 // independent. Skip through any number of them. Bail out if the stores
1556 // are in an endless dead cycle and report no progress. This is a key
1557 // transform for Reflection. However, if after skipping through the Stores
1558 // we can't then fold up against a prior store do NOT do the transform as
1559 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
1560 // array memory alive twice: once for the hoisted Load and again after the
1561 // bypassed Store. This situation only works if EVERYBODY who does
1562 // anti-dependence work knows how to bypass. I.e. we need all
1563 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
1564 // the alias index stuff. So instead, peek through Stores and IFF we can
1565 // fold up, do so.
1566 Node* prev_mem = find_previous_store(phase);
1567 // Steps (a), (b): Walk past independent stores to find an exact match.
1568 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) {
1569 // (c) See if we can fold up on the spot, but don't fold up here.
1570 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
1571 // just return a prior value, which is done by Identity calls.
1572 if (can_see_stored_value(prev_mem, phase)) {
1573 // Make ready for step (d):
1574 set_req(MemNode::Memory, prev_mem);
1575 return this;
1576 }
1577 }
1579 return NULL; // No further progress
1580 }
1582 // Helper to recognize certain Klass fields which are invariant across
1583 // some group of array types (e.g., int[] or all T[] where T < Object).
1584 const Type*
1585 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1586 ciKlass* klass) const {
1587 if (tkls->offset() == in_bytes(Klass::modifier_flags_offset())) {
1588 // The field is Klass::_modifier_flags. Return its (constant) value.
1589 // (Folds up the 2nd indirection in aClassConstant.getModifiers().)
1590 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags");
1591 return TypeInt::make(klass->modifier_flags());
1592 }
1593 if (tkls->offset() == in_bytes(Klass::access_flags_offset())) {
1594 // The field is Klass::_access_flags. Return its (constant) value.
1595 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1596 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags");
1597 return TypeInt::make(klass->access_flags());
1598 }
1599 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) {
1600 // The field is Klass::_layout_helper. Return its constant value if known.
1601 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper");
1602 return TypeInt::make(klass->layout_helper());
1603 }
1605 // No match.
1606 return NULL;
1607 }
1609 // Try to constant-fold a stable array element.
1610 static const Type* fold_stable_ary_elem(const TypeAryPtr* ary, int off, BasicType loadbt) {
1611 assert(ary->const_oop(), "array should be constant");
1612 assert(ary->is_stable(), "array should be stable");
1614 // Decode the results of GraphKit::array_element_address.
1615 ciArray* aobj = ary->const_oop()->as_array();
1616 ciConstant con = aobj->element_value_by_offset(off);
1618 if (con.basic_type() != T_ILLEGAL && !con.is_null_or_zero()) {
1619 const Type* con_type = Type::make_from_constant(con);
1620 if (con_type != NULL) {
1621 if (con_type->isa_aryptr()) {
1622 // Join with the array element type, in case it is also stable.
1623 int dim = ary->stable_dimension();
1624 con_type = con_type->is_aryptr()->cast_to_stable(true, dim-1);
1625 }
1626 if (loadbt == T_NARROWOOP && con_type->isa_oopptr()) {
1627 con_type = con_type->make_narrowoop();
1628 }
1629 #ifndef PRODUCT
1630 if (TraceIterativeGVN) {
1631 tty->print("FoldStableValues: array element [off=%d]: con_type=", off);
1632 con_type->dump(); tty->cr();
1633 }
1634 #endif //PRODUCT
1635 return con_type;
1636 }
1637 }
1638 return NULL;
1639 }
1641 //------------------------------Value-----------------------------------------
1642 const Type *LoadNode::Value( PhaseTransform *phase ) const {
1643 // Either input is TOP ==> the result is TOP
1644 Node* mem = in(MemNode::Memory);
1645 const Type *t1 = phase->type(mem);
1646 if (t1 == Type::TOP) return Type::TOP;
1647 Node* adr = in(MemNode::Address);
1648 const TypePtr* tp = phase->type(adr)->isa_ptr();
1649 if (tp == NULL || tp->empty()) return Type::TOP;
1650 int off = tp->offset();
1651 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
1652 Compile* C = phase->C;
1654 // Try to guess loaded type from pointer type
1655 if (tp->isa_aryptr()) {
1656 const TypeAryPtr* ary = tp->is_aryptr();
1657 const Type* t = ary->elem();
1659 // Determine whether the reference is beyond the header or not, by comparing
1660 // the offset against the offset of the start of the array's data.
1661 // Different array types begin at slightly different offsets (12 vs. 16).
1662 // We choose T_BYTE as an example base type that is least restrictive
1663 // as to alignment, which will therefore produce the smallest
1664 // possible base offset.
1665 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
1666 const bool off_beyond_header = ((uint)off >= (uint)min_base_off);
1668 // Try to constant-fold a stable array element.
1669 if (FoldStableValues && ary->is_stable() && ary->const_oop() != NULL) {
1670 // Make sure the reference is not into the header and the offset is constant
1671 if (off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) {
1672 const Type* con_type = fold_stable_ary_elem(ary, off, memory_type());
1673 if (con_type != NULL) {
1674 return con_type;
1675 }
1676 }
1677 }
1679 // Don't do this for integer types. There is only potential profit if
1680 // the element type t is lower than _type; that is, for int types, if _type is
1681 // more restrictive than t. This only happens here if one is short and the other
1682 // char (both 16 bits), and in those cases we've made an intentional decision
1683 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
1684 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
1685 //
1686 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
1687 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
1688 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
1689 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
1690 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
1691 // In fact, that could have been the original type of p1, and p1 could have
1692 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
1693 // expression (LShiftL quux 3) independently optimized to the constant 8.
1694 if ((t->isa_int() == NULL) && (t->isa_long() == NULL)
1695 && (_type->isa_vect() == NULL)
1696 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
1697 // t might actually be lower than _type, if _type is a unique
1698 // concrete subclass of abstract class t.
1699 if (off_beyond_header) { // is the offset beyond the header?
1700 const Type* jt = t->join_speculative(_type);
1701 // In any case, do not allow the join, per se, to empty out the type.
1702 if (jt->empty() && !t->empty()) {
1703 // This can happen if a interface-typed array narrows to a class type.
1704 jt = _type;
1705 }
1706 #ifdef ASSERT
1707 if (phase->C->eliminate_boxing() && adr->is_AddP()) {
1708 // The pointers in the autobox arrays are always non-null
1709 Node* base = adr->in(AddPNode::Base);
1710 if ((base != NULL) && base->is_DecodeN()) {
1711 // Get LoadN node which loads IntegerCache.cache field
1712 base = base->in(1);
1713 }
1714 if ((base != NULL) && base->is_Con()) {
1715 const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr();
1716 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1717 // It could be narrow oop
1718 assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity");
1719 }
1720 }
1721 }
1722 #endif
1723 return jt;
1724 }
1725 }
1726 } else if (tp->base() == Type::InstPtr) {
1727 ciEnv* env = C->env();
1728 const TypeInstPtr* tinst = tp->is_instptr();
1729 ciKlass* klass = tinst->klass();
1730 assert( off != Type::OffsetBot ||
1731 // arrays can be cast to Objects
1732 tp->is_oopptr()->klass()->is_java_lang_Object() ||
1733 // unsafe field access may not have a constant offset
1734 C->has_unsafe_access(),
1735 "Field accesses must be precise" );
1736 // For oop loads, we expect the _type to be precise
1737 if (klass == env->String_klass() &&
1738 adr->is_AddP() && off != Type::OffsetBot) {
1739 // For constant Strings treat the final fields as compile time constants.
1740 Node* base = adr->in(AddPNode::Base);
1741 const TypeOopPtr* t = phase->type(base)->isa_oopptr();
1742 if (t != NULL && t->singleton()) {
1743 ciField* field = env->String_klass()->get_field_by_offset(off, false);
1744 if (field != NULL && field->is_final()) {
1745 ciObject* string = t->const_oop();
1746 ciConstant constant = string->as_instance()->field_value(field);
1747 if (constant.basic_type() == T_INT) {
1748 return TypeInt::make(constant.as_int());
1749 } else if (constant.basic_type() == T_ARRAY) {
1750 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
1751 return TypeNarrowOop::make_from_constant(constant.as_object(), true);
1752 } else {
1753 return TypeOopPtr::make_from_constant(constant.as_object(), true);
1754 }
1755 }
1756 }
1757 }
1758 }
1759 // Optimizations for constant objects
1760 ciObject* const_oop = tinst->const_oop();
1761 if (const_oop != NULL) {
1762 // For constant Boxed value treat the target field as a compile time constant.
1763 if (tinst->is_ptr_to_boxed_value()) {
1764 return tinst->get_const_boxed_value();
1765 } else
1766 // For constant CallSites treat the target field as a compile time constant.
1767 if (const_oop->is_call_site()) {
1768 ciCallSite* call_site = const_oop->as_call_site();
1769 ciField* field = call_site->klass()->as_instance_klass()->get_field_by_offset(off, /*is_static=*/ false);
1770 if (field != NULL && field->is_call_site_target()) {
1771 ciMethodHandle* target = call_site->get_target();
1772 if (target != NULL) { // just in case
1773 ciConstant constant(T_OBJECT, target);
1774 const Type* t;
1775 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
1776 t = TypeNarrowOop::make_from_constant(constant.as_object(), true);
1777 } else {
1778 t = TypeOopPtr::make_from_constant(constant.as_object(), true);
1779 }
1780 // Add a dependence for invalidation of the optimization.
1781 if (!call_site->is_constant_call_site()) {
1782 C->dependencies()->assert_call_site_target_value(call_site, target);
1783 }
1784 return t;
1785 }
1786 }
1787 }
1788 }
1789 } else if (tp->base() == Type::KlassPtr) {
1790 assert( off != Type::OffsetBot ||
1791 // arrays can be cast to Objects
1792 tp->is_klassptr()->klass()->is_java_lang_Object() ||
1793 // also allow array-loading from the primary supertype
1794 // array during subtype checks
1795 Opcode() == Op_LoadKlass,
1796 "Field accesses must be precise" );
1797 // For klass/static loads, we expect the _type to be precise
1798 }
1800 const TypeKlassPtr *tkls = tp->isa_klassptr();
1801 if (tkls != NULL && !StressReflectiveCode) {
1802 ciKlass* klass = tkls->klass();
1803 if (klass->is_loaded() && tkls->klass_is_exact()) {
1804 // We are loading a field from a Klass metaobject whose identity
1805 // is known at compile time (the type is "exact" or "precise").
1806 // Check for fields we know are maintained as constants by the VM.
1807 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) {
1808 // The field is Klass::_super_check_offset. Return its (constant) value.
1809 // (Folds up type checking code.)
1810 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
1811 return TypeInt::make(klass->super_check_offset());
1812 }
1813 // Compute index into primary_supers array
1814 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1815 // Check for overflowing; use unsigned compare to handle the negative case.
1816 if( depth < ciKlass::primary_super_limit() ) {
1817 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1818 // (Folds up type checking code.)
1819 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1820 ciKlass *ss = klass->super_of_depth(depth);
1821 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1822 }
1823 const Type* aift = load_array_final_field(tkls, klass);
1824 if (aift != NULL) return aift;
1825 if (tkls->offset() == in_bytes(ArrayKlass::component_mirror_offset())
1826 && klass->is_array_klass()) {
1827 // The field is ArrayKlass::_component_mirror. Return its (constant) value.
1828 // (Folds up aClassConstant.getComponentType, common in Arrays.copyOf.)
1829 assert(Opcode() == Op_LoadP, "must load an oop from _component_mirror");
1830 return TypeInstPtr::make(klass->as_array_klass()->component_mirror());
1831 }
1832 if (tkls->offset() == in_bytes(Klass::java_mirror_offset())) {
1833 // The field is Klass::_java_mirror. Return its (constant) value.
1834 // (Folds up the 2nd indirection in anObjConstant.getClass().)
1835 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
1836 return TypeInstPtr::make(klass->java_mirror());
1837 }
1838 }
1840 // We can still check if we are loading from the primary_supers array at a
1841 // shallow enough depth. Even though the klass is not exact, entries less
1842 // than or equal to its super depth are correct.
1843 if (klass->is_loaded() ) {
1844 ciType *inner = klass;
1845 while( inner->is_obj_array_klass() )
1846 inner = inner->as_obj_array_klass()->base_element_type();
1847 if( inner->is_instance_klass() &&
1848 !inner->as_instance_klass()->flags().is_interface() ) {
1849 // Compute index into primary_supers array
1850 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1851 // Check for overflowing; use unsigned compare to handle the negative case.
1852 if( depth < ciKlass::primary_super_limit() &&
1853 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case
1854 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1855 // (Folds up type checking code.)
1856 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1857 ciKlass *ss = klass->super_of_depth(depth);
1858 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1859 }
1860 }
1861 }
1863 // If the type is enough to determine that the thing is not an array,
1864 // we can give the layout_helper a positive interval type.
1865 // This will help short-circuit some reflective code.
1866 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())
1867 && !klass->is_array_klass() // not directly typed as an array
1868 && !klass->is_interface() // specifically not Serializable & Cloneable
1869 && !klass->is_java_lang_Object() // not the supertype of all T[]
1870 ) {
1871 // Note: When interfaces are reliable, we can narrow the interface
1872 // test to (klass != Serializable && klass != Cloneable).
1873 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
1874 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
1875 // The key property of this type is that it folds up tests
1876 // for array-ness, since it proves that the layout_helper is positive.
1877 // Thus, a generic value like the basic object layout helper works fine.
1878 return TypeInt::make(min_size, max_jint, Type::WidenMin);
1879 }
1880 }
1882 // If we are loading from a freshly-allocated object, produce a zero,
1883 // if the load is provably beyond the header of the object.
1884 // (Also allow a variable load from a fresh array to produce zero.)
1885 const TypeOopPtr *tinst = tp->isa_oopptr();
1886 bool is_instance = (tinst != NULL) && tinst->is_known_instance_field();
1887 bool is_boxed_value = (tinst != NULL) && tinst->is_ptr_to_boxed_value();
1888 if (ReduceFieldZeroing || is_instance || is_boxed_value) {
1889 Node* value = can_see_stored_value(mem,phase);
1890 if (value != NULL && value->is_Con()) {
1891 assert(value->bottom_type()->higher_equal(_type),"sanity");
1892 return value->bottom_type();
1893 }
1894 }
1896 if (is_instance) {
1897 // If we have an instance type and our memory input is the
1898 // programs's initial memory state, there is no matching store,
1899 // so just return a zero of the appropriate type
1900 Node *mem = in(MemNode::Memory);
1901 if (mem->is_Parm() && mem->in(0)->is_Start()) {
1902 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
1903 return Type::get_zero_type(_type->basic_type());
1904 }
1905 }
1906 return _type;
1907 }
1909 //------------------------------match_edge-------------------------------------
1910 // Do we Match on this edge index or not? Match only the address.
1911 uint LoadNode::match_edge(uint idx) const {
1912 return idx == MemNode::Address;
1913 }
1915 //--------------------------LoadBNode::Ideal--------------------------------------
1916 //
1917 // If the previous store is to the same address as this load,
1918 // and the value stored was larger than a byte, replace this load
1919 // with the value stored truncated to a byte. If no truncation is
1920 // needed, the replacement is done in LoadNode::Identity().
1921 //
1922 Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1923 Node* mem = in(MemNode::Memory);
1924 Node* value = can_see_stored_value(mem,phase);
1925 if( value && !phase->type(value)->higher_equal( _type ) ) {
1926 Node *result = phase->transform( new (phase->C) LShiftINode(value, phase->intcon(24)) );
1927 return new (phase->C) RShiftINode(result, phase->intcon(24));
1928 }
1929 // Identity call will handle the case where truncation is not needed.
1930 return LoadNode::Ideal(phase, can_reshape);
1931 }
1933 const Type* LoadBNode::Value(PhaseTransform *phase) const {
1934 Node* mem = in(MemNode::Memory);
1935 Node* value = can_see_stored_value(mem,phase);
1936 if (value != NULL && value->is_Con() &&
1937 !value->bottom_type()->higher_equal(_type)) {
1938 // If the input to the store does not fit with the load's result type,
1939 // it must be truncated. We can't delay until Ideal call since
1940 // a singleton Value is needed for split_thru_phi optimization.
1941 int con = value->get_int();
1942 return TypeInt::make((con << 24) >> 24);
1943 }
1944 return LoadNode::Value(phase);
1945 }
1947 //--------------------------LoadUBNode::Ideal-------------------------------------
1948 //
1949 // If the previous store is to the same address as this load,
1950 // and the value stored was larger than a byte, replace this load
1951 // with the value stored truncated to a byte. If no truncation is
1952 // needed, the replacement is done in LoadNode::Identity().
1953 //
1954 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
1955 Node* mem = in(MemNode::Memory);
1956 Node* value = can_see_stored_value(mem, phase);
1957 if (value && !phase->type(value)->higher_equal(_type))
1958 return new (phase->C) AndINode(value, phase->intcon(0xFF));
1959 // Identity call will handle the case where truncation is not needed.
1960 return LoadNode::Ideal(phase, can_reshape);
1961 }
1963 const Type* LoadUBNode::Value(PhaseTransform *phase) const {
1964 Node* mem = in(MemNode::Memory);
1965 Node* value = can_see_stored_value(mem,phase);
1966 if (value != NULL && value->is_Con() &&
1967 !value->bottom_type()->higher_equal(_type)) {
1968 // If the input to the store does not fit with the load's result type,
1969 // it must be truncated. We can't delay until Ideal call since
1970 // a singleton Value is needed for split_thru_phi optimization.
1971 int con = value->get_int();
1972 return TypeInt::make(con & 0xFF);
1973 }
1974 return LoadNode::Value(phase);
1975 }
1977 //--------------------------LoadUSNode::Ideal-------------------------------------
1978 //
1979 // If the previous store is to the same address as this load,
1980 // and the value stored was larger than a char, replace this load
1981 // with the value stored truncated to a char. If no truncation is
1982 // needed, the replacement is done in LoadNode::Identity().
1983 //
1984 Node *LoadUSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1985 Node* mem = in(MemNode::Memory);
1986 Node* value = can_see_stored_value(mem,phase);
1987 if( value && !phase->type(value)->higher_equal( _type ) )
1988 return new (phase->C) AndINode(value,phase->intcon(0xFFFF));
1989 // Identity call will handle the case where truncation is not needed.
1990 return LoadNode::Ideal(phase, can_reshape);
1991 }
1993 const Type* LoadUSNode::Value(PhaseTransform *phase) const {
1994 Node* mem = in(MemNode::Memory);
1995 Node* value = can_see_stored_value(mem,phase);
1996 if (value != NULL && value->is_Con() &&
1997 !value->bottom_type()->higher_equal(_type)) {
1998 // If the input to the store does not fit with the load's result type,
1999 // it must be truncated. We can't delay until Ideal call since
2000 // a singleton Value is needed for split_thru_phi optimization.
2001 int con = value->get_int();
2002 return TypeInt::make(con & 0xFFFF);
2003 }
2004 return LoadNode::Value(phase);
2005 }
2007 //--------------------------LoadSNode::Ideal--------------------------------------
2008 //
2009 // If the previous store is to the same address as this load,
2010 // and the value stored was larger than a short, replace this load
2011 // with the value stored truncated to a short. If no truncation is
2012 // needed, the replacement is done in LoadNode::Identity().
2013 //
2014 Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2015 Node* mem = in(MemNode::Memory);
2016 Node* value = can_see_stored_value(mem,phase);
2017 if( value && !phase->type(value)->higher_equal( _type ) ) {
2018 Node *result = phase->transform( new (phase->C) LShiftINode(value, phase->intcon(16)) );
2019 return new (phase->C) RShiftINode(result, phase->intcon(16));
2020 }
2021 // Identity call will handle the case where truncation is not needed.
2022 return LoadNode::Ideal(phase, can_reshape);
2023 }
2025 const Type* LoadSNode::Value(PhaseTransform *phase) const {
2026 Node* mem = in(MemNode::Memory);
2027 Node* value = can_see_stored_value(mem,phase);
2028 if (value != NULL && value->is_Con() &&
2029 !value->bottom_type()->higher_equal(_type)) {
2030 // If the input to the store does not fit with the load's result type,
2031 // it must be truncated. We can't delay until Ideal call since
2032 // a singleton Value is needed for split_thru_phi optimization.
2033 int con = value->get_int();
2034 return TypeInt::make((con << 16) >> 16);
2035 }
2036 return LoadNode::Value(phase);
2037 }
2039 //=============================================================================
2040 //----------------------------LoadKlassNode::make------------------------------
2041 // Polymorphic factory method:
2042 Node* LoadKlassNode::make(PhaseGVN& gvn, Node* ctl, Node *mem, Node *adr, const TypePtr* at, const TypeKlassPtr *tk) {
2043 Compile* C = gvn.C;
2044 // sanity check the alias category against the created node type
2045 const TypePtr *adr_type = adr->bottom_type()->isa_ptr();
2046 assert(adr_type != NULL, "expecting TypeKlassPtr");
2047 #ifdef _LP64
2048 if (adr_type->is_ptr_to_narrowklass()) {
2049 assert(UseCompressedClassPointers, "no compressed klasses");
2050 Node* load_klass = gvn.transform(new (C) LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowklass(), MemNode::unordered));
2051 return new (C) DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr());
2052 }
2053 #endif
2054 assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
2055 return new (C) LoadKlassNode(ctl, mem, adr, at, tk, MemNode::unordered);
2056 }
2058 //------------------------------Value------------------------------------------
2059 const Type *LoadKlassNode::Value( PhaseTransform *phase ) const {
2060 return klass_value_common(phase);
2061 }
2063 // In most cases, LoadKlassNode does not have the control input set. If the control
2064 // input is set, it must not be removed (by LoadNode::Ideal()).
2065 bool LoadKlassNode::can_remove_control() const {
2066 return false;
2067 }
2069 const Type *LoadNode::klass_value_common( PhaseTransform *phase ) const {
2070 // Either input is TOP ==> the result is TOP
2071 const Type *t1 = phase->type( in(MemNode::Memory) );
2072 if (t1 == Type::TOP) return Type::TOP;
2073 Node *adr = in(MemNode::Address);
2074 const Type *t2 = phase->type( adr );
2075 if (t2 == Type::TOP) return Type::TOP;
2076 const TypePtr *tp = t2->is_ptr();
2077 if (TypePtr::above_centerline(tp->ptr()) ||
2078 tp->ptr() == TypePtr::Null) return Type::TOP;
2080 // Return a more precise klass, if possible
2081 const TypeInstPtr *tinst = tp->isa_instptr();
2082 if (tinst != NULL) {
2083 ciInstanceKlass* ik = tinst->klass()->as_instance_klass();
2084 int offset = tinst->offset();
2085 if (ik == phase->C->env()->Class_klass()
2086 && (offset == java_lang_Class::klass_offset_in_bytes() ||
2087 offset == java_lang_Class::array_klass_offset_in_bytes())) {
2088 // We are loading a special hidden field from a Class mirror object,
2089 // the field which points to the VM's Klass metaobject.
2090 ciType* t = tinst->java_mirror_type();
2091 // java_mirror_type returns non-null for compile-time Class constants.
2092 if (t != NULL) {
2093 // constant oop => constant klass
2094 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
2095 if (t->is_void()) {
2096 // We cannot create a void array. Since void is a primitive type return null
2097 // klass. Users of this result need to do a null check on the returned klass.
2098 return TypePtr::NULL_PTR;
2099 }
2100 return TypeKlassPtr::make(ciArrayKlass::make(t));
2101 }
2102 if (!t->is_klass()) {
2103 // a primitive Class (e.g., int.class) has NULL for a klass field
2104 return TypePtr::NULL_PTR;
2105 }
2106 // (Folds up the 1st indirection in aClassConstant.getModifiers().)
2107 return TypeKlassPtr::make(t->as_klass());
2108 }
2109 // non-constant mirror, so we can't tell what's going on
2110 }
2111 if( !ik->is_loaded() )
2112 return _type; // Bail out if not loaded
2113 if (offset == oopDesc::klass_offset_in_bytes()) {
2114 if (tinst->klass_is_exact()) {
2115 return TypeKlassPtr::make(ik);
2116 }
2117 // See if we can become precise: no subklasses and no interface
2118 // (Note: We need to support verified interfaces.)
2119 if (!ik->is_interface() && !ik->has_subklass()) {
2120 //assert(!UseExactTypes, "this code should be useless with exact types");
2121 // Add a dependence; if any subclass added we need to recompile
2122 if (!ik->is_final()) {
2123 // %%% should use stronger assert_unique_concrete_subtype instead
2124 phase->C->dependencies()->assert_leaf_type(ik);
2125 }
2126 // Return precise klass
2127 return TypeKlassPtr::make(ik);
2128 }
2130 // Return root of possible klass
2131 return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/);
2132 }
2133 }
2135 // Check for loading klass from an array
2136 const TypeAryPtr *tary = tp->isa_aryptr();
2137 if( tary != NULL ) {
2138 ciKlass *tary_klass = tary->klass();
2139 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP
2140 && tary->offset() == oopDesc::klass_offset_in_bytes()) {
2141 if (tary->klass_is_exact()) {
2142 return TypeKlassPtr::make(tary_klass);
2143 }
2144 ciArrayKlass *ak = tary->klass()->as_array_klass();
2145 // If the klass is an object array, we defer the question to the
2146 // array component klass.
2147 if( ak->is_obj_array_klass() ) {
2148 assert( ak->is_loaded(), "" );
2149 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass();
2150 if( base_k->is_loaded() && base_k->is_instance_klass() ) {
2151 ciInstanceKlass* ik = base_k->as_instance_klass();
2152 // See if we can become precise: no subklasses and no interface
2153 if (!ik->is_interface() && !ik->has_subklass()) {
2154 //assert(!UseExactTypes, "this code should be useless with exact types");
2155 // Add a dependence; if any subclass added we need to recompile
2156 if (!ik->is_final()) {
2157 phase->C->dependencies()->assert_leaf_type(ik);
2158 }
2159 // Return precise array klass
2160 return TypeKlassPtr::make(ak);
2161 }
2162 }
2163 return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/);
2164 } else { // Found a type-array?
2165 //assert(!UseExactTypes, "this code should be useless with exact types");
2166 assert( ak->is_type_array_klass(), "" );
2167 return TypeKlassPtr::make(ak); // These are always precise
2168 }
2169 }
2170 }
2172 // Check for loading klass from an array klass
2173 const TypeKlassPtr *tkls = tp->isa_klassptr();
2174 if (tkls != NULL && !StressReflectiveCode) {
2175 ciKlass* klass = tkls->klass();
2176 if( !klass->is_loaded() )
2177 return _type; // Bail out if not loaded
2178 if( klass->is_obj_array_klass() &&
2179 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) {
2180 ciKlass* elem = klass->as_obj_array_klass()->element_klass();
2181 // // Always returning precise element type is incorrect,
2182 // // e.g., element type could be object and array may contain strings
2183 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
2185 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
2186 // according to the element type's subclassing.
2187 return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/);
2188 }
2189 if( klass->is_instance_klass() && tkls->klass_is_exact() &&
2190 tkls->offset() == in_bytes(Klass::super_offset())) {
2191 ciKlass* sup = klass->as_instance_klass()->super();
2192 // The field is Klass::_super. Return its (constant) value.
2193 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
2194 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR;
2195 }
2196 }
2198 // Bailout case
2199 return LoadNode::Value(phase);
2200 }
2202 //------------------------------Identity---------------------------------------
2203 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
2204 // Also feed through the klass in Allocate(...klass...)._klass.
2205 Node* LoadKlassNode::Identity( PhaseTransform *phase ) {
2206 return klass_identity_common(phase);
2207 }
2209 Node* LoadNode::klass_identity_common(PhaseTransform *phase ) {
2210 Node* x = LoadNode::Identity(phase);
2211 if (x != this) return x;
2213 // Take apart the address into an oop and and offset.
2214 // Return 'this' if we cannot.
2215 Node* adr = in(MemNode::Address);
2216 intptr_t offset = 0;
2217 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2218 if (base == NULL) return this;
2219 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
2220 if (toop == NULL) return this;
2222 // We can fetch the klass directly through an AllocateNode.
2223 // This works even if the klass is not constant (clone or newArray).
2224 if (offset == oopDesc::klass_offset_in_bytes()) {
2225 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
2226 if (allocated_klass != NULL) {
2227 return allocated_klass;
2228 }
2229 }
2231 // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*.
2232 // Simplify ak.component_mirror.array_klass to plain ak, ak an ArrayKlass.
2233 // See inline_native_Class_query for occurrences of these patterns.
2234 // Java Example: x.getClass().isAssignableFrom(y)
2235 // Java Example: Array.newInstance(x.getClass().getComponentType(), n)
2236 //
2237 // This improves reflective code, often making the Class
2238 // mirror go completely dead. (Current exception: Class
2239 // mirrors may appear in debug info, but we could clean them out by
2240 // introducing a new debug info operator for Klass*.java_mirror).
2241 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass()
2242 && (offset == java_lang_Class::klass_offset_in_bytes() ||
2243 offset == java_lang_Class::array_klass_offset_in_bytes())) {
2244 // We are loading a special hidden field from a Class mirror,
2245 // the field which points to its Klass or ArrayKlass metaobject.
2246 if (base->is_Load()) {
2247 Node* adr2 = base->in(MemNode::Address);
2248 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2249 if (tkls != NULL && !tkls->empty()
2250 && (tkls->klass()->is_instance_klass() ||
2251 tkls->klass()->is_array_klass())
2252 && adr2->is_AddP()
2253 ) {
2254 int mirror_field = in_bytes(Klass::java_mirror_offset());
2255 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
2256 mirror_field = in_bytes(ArrayKlass::component_mirror_offset());
2257 }
2258 if (tkls->offset() == mirror_field) {
2259 return adr2->in(AddPNode::Base);
2260 }
2261 }
2262 }
2263 }
2265 return this;
2266 }
2269 //------------------------------Value------------------------------------------
2270 const Type *LoadNKlassNode::Value( PhaseTransform *phase ) const {
2271 const Type *t = klass_value_common(phase);
2272 if (t == Type::TOP)
2273 return t;
2275 return t->make_narrowklass();
2276 }
2278 //------------------------------Identity---------------------------------------
2279 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
2280 // Also feed through the klass in Allocate(...klass...)._klass.
2281 Node* LoadNKlassNode::Identity( PhaseTransform *phase ) {
2282 Node *x = klass_identity_common(phase);
2284 const Type *t = phase->type( x );
2285 if( t == Type::TOP ) return x;
2286 if( t->isa_narrowklass()) return x;
2287 assert (!t->isa_narrowoop(), "no narrow oop here");
2289 return phase->transform(new (phase->C) EncodePKlassNode(x, t->make_narrowklass()));
2290 }
2292 //------------------------------Value-----------------------------------------
2293 const Type *LoadRangeNode::Value( PhaseTransform *phase ) const {
2294 // Either input is TOP ==> the result is TOP
2295 const Type *t1 = phase->type( in(MemNode::Memory) );
2296 if( t1 == Type::TOP ) return Type::TOP;
2297 Node *adr = in(MemNode::Address);
2298 const Type *t2 = phase->type( adr );
2299 if( t2 == Type::TOP ) return Type::TOP;
2300 const TypePtr *tp = t2->is_ptr();
2301 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
2302 const TypeAryPtr *tap = tp->isa_aryptr();
2303 if( !tap ) return _type;
2304 return tap->size();
2305 }
2307 //-------------------------------Ideal---------------------------------------
2308 // Feed through the length in AllocateArray(...length...)._length.
2309 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2310 Node* p = MemNode::Ideal_common(phase, can_reshape);
2311 if (p) return (p == NodeSentinel) ? NULL : p;
2313 // Take apart the address into an oop and and offset.
2314 // Return 'this' if we cannot.
2315 Node* adr = in(MemNode::Address);
2316 intptr_t offset = 0;
2317 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2318 if (base == NULL) return NULL;
2319 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2320 if (tary == NULL) return NULL;
2322 // We can fetch the length directly through an AllocateArrayNode.
2323 // This works even if the length is not constant (clone or newArray).
2324 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2325 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2326 if (alloc != NULL) {
2327 Node* allocated_length = alloc->Ideal_length();
2328 Node* len = alloc->make_ideal_length(tary, phase);
2329 if (allocated_length != len) {
2330 // New CastII improves on this.
2331 return len;
2332 }
2333 }
2334 }
2336 return NULL;
2337 }
2339 //------------------------------Identity---------------------------------------
2340 // Feed through the length in AllocateArray(...length...)._length.
2341 Node* LoadRangeNode::Identity( PhaseTransform *phase ) {
2342 Node* x = LoadINode::Identity(phase);
2343 if (x != this) return x;
2345 // Take apart the address into an oop and and offset.
2346 // Return 'this' if we cannot.
2347 Node* adr = in(MemNode::Address);
2348 intptr_t offset = 0;
2349 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2350 if (base == NULL) return this;
2351 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2352 if (tary == NULL) return this;
2354 // We can fetch the length directly through an AllocateArrayNode.
2355 // This works even if the length is not constant (clone or newArray).
2356 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2357 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2358 if (alloc != NULL) {
2359 Node* allocated_length = alloc->Ideal_length();
2360 // Do not allow make_ideal_length to allocate a CastII node.
2361 Node* len = alloc->make_ideal_length(tary, phase, false);
2362 if (allocated_length == len) {
2363 // Return allocated_length only if it would not be improved by a CastII.
2364 return allocated_length;
2365 }
2366 }
2367 }
2369 return this;
2371 }
2373 //=============================================================================
2374 //---------------------------StoreNode::make-----------------------------------
2375 // Polymorphic factory method:
2376 StoreNode* StoreNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt, MemOrd mo) {
2377 assert((mo == unordered || mo == release), "unexpected");
2378 Compile* C = gvn.C;
2379 assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2380 ctl != NULL, "raw memory operations should have control edge");
2382 switch (bt) {
2383 case T_BOOLEAN: val = gvn.transform(new (C) AndINode(val, gvn.intcon(0x1))); // Fall through to T_BYTE case
2384 case T_BYTE: return new (C) StoreBNode(ctl, mem, adr, adr_type, val, mo);
2385 case T_INT: return new (C) StoreINode(ctl, mem, adr, adr_type, val, mo);
2386 case T_CHAR:
2387 case T_SHORT: return new (C) StoreCNode(ctl, mem, adr, adr_type, val, mo);
2388 case T_LONG: return new (C) StoreLNode(ctl, mem, adr, adr_type, val, mo);
2389 case T_FLOAT: return new (C) StoreFNode(ctl, mem, adr, adr_type, val, mo);
2390 case T_DOUBLE: return new (C) StoreDNode(ctl, mem, adr, adr_type, val, mo);
2391 case T_METADATA:
2392 case T_ADDRESS:
2393 case T_OBJECT:
2394 #ifdef _LP64
2395 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
2396 val = gvn.transform(new (C) EncodePNode(val, val->bottom_type()->make_narrowoop()));
2397 return new (C) StoreNNode(ctl, mem, adr, adr_type, val, mo);
2398 } else if (adr->bottom_type()->is_ptr_to_narrowklass() ||
2399 (UseCompressedClassPointers && val->bottom_type()->isa_klassptr() &&
2400 adr->bottom_type()->isa_rawptr())) {
2401 val = gvn.transform(new (C) EncodePKlassNode(val, val->bottom_type()->make_narrowklass()));
2402 return new (C) StoreNKlassNode(ctl, mem, adr, adr_type, val, mo);
2403 }
2404 #endif
2405 {
2406 return new (C) StorePNode(ctl, mem, adr, adr_type, val, mo);
2407 }
2408 }
2409 ShouldNotReachHere();
2410 return (StoreNode*)NULL;
2411 }
2413 StoreLNode* StoreLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
2414 bool require_atomic = true;
2415 return new (C) StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
2416 }
2418 StoreDNode* StoreDNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
2419 bool require_atomic = true;
2420 return new (C) StoreDNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
2421 }
2424 //--------------------------bottom_type----------------------------------------
2425 const Type *StoreNode::bottom_type() const {
2426 return Type::MEMORY;
2427 }
2429 //------------------------------hash-------------------------------------------
2430 uint StoreNode::hash() const {
2431 // unroll addition of interesting fields
2432 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2434 // Since they are not commoned, do not hash them:
2435 return NO_HASH;
2436 }
2438 //------------------------------Ideal------------------------------------------
2439 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
2440 // When a store immediately follows a relevant allocation/initialization,
2441 // try to capture it into the initialization, or hoist it above.
2442 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2443 Node* p = MemNode::Ideal_common(phase, can_reshape);
2444 if (p) return (p == NodeSentinel) ? NULL : p;
2446 Node* mem = in(MemNode::Memory);
2447 Node* address = in(MemNode::Address);
2449 // Back-to-back stores to same address? Fold em up. Generally
2450 // unsafe if I have intervening uses... Also disallowed for StoreCM
2451 // since they must follow each StoreP operation. Redundant StoreCMs
2452 // are eliminated just before matching in final_graph_reshape.
2453 if (mem->is_Store() && mem->in(MemNode::Address)->eqv_uncast(address) &&
2454 mem->Opcode() != Op_StoreCM) {
2455 // Looking at a dead closed cycle of memory?
2456 assert(mem != mem->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
2458 assert(Opcode() == mem->Opcode() ||
2459 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw,
2460 "no mismatched stores, except on raw memory");
2462 if (mem->outcnt() == 1 && // check for intervening uses
2463 mem->as_Store()->memory_size() <= this->memory_size()) {
2464 // If anybody other than 'this' uses 'mem', we cannot fold 'mem' away.
2465 // For example, 'mem' might be the final state at a conditional return.
2466 // Or, 'mem' might be used by some node which is live at the same time
2467 // 'this' is live, which might be unschedulable. So, require exactly
2468 // ONE user, the 'this' store, until such time as we clone 'mem' for
2469 // each of 'mem's uses (thus making the exactly-1-user-rule hold true).
2470 if (can_reshape) { // (%%% is this an anachronism?)
2471 set_req_X(MemNode::Memory, mem->in(MemNode::Memory),
2472 phase->is_IterGVN());
2473 } else {
2474 // It's OK to do this in the parser, since DU info is always accurate,
2475 // and the parser always refers to nodes via SafePointNode maps.
2476 set_req(MemNode::Memory, mem->in(MemNode::Memory));
2477 }
2478 return this;
2479 }
2480 }
2482 // Capture an unaliased, unconditional, simple store into an initializer.
2483 // Or, if it is independent of the allocation, hoist it above the allocation.
2484 if (ReduceFieldZeroing && /*can_reshape &&*/
2485 mem->is_Proj() && mem->in(0)->is_Initialize()) {
2486 InitializeNode* init = mem->in(0)->as_Initialize();
2487 intptr_t offset = init->can_capture_store(this, phase, can_reshape);
2488 if (offset > 0) {
2489 Node* moved = init->capture_store(this, offset, phase, can_reshape);
2490 // If the InitializeNode captured me, it made a raw copy of me,
2491 // and I need to disappear.
2492 if (moved != NULL) {
2493 // %%% hack to ensure that Ideal returns a new node:
2494 mem = MergeMemNode::make(phase->C, mem);
2495 return mem; // fold me away
2496 }
2497 }
2498 }
2500 return NULL; // No further progress
2501 }
2503 //------------------------------Value-----------------------------------------
2504 const Type *StoreNode::Value( PhaseTransform *phase ) const {
2505 // Either input is TOP ==> the result is TOP
2506 const Type *t1 = phase->type( in(MemNode::Memory) );
2507 if( t1 == Type::TOP ) return Type::TOP;
2508 const Type *t2 = phase->type( in(MemNode::Address) );
2509 if( t2 == Type::TOP ) return Type::TOP;
2510 const Type *t3 = phase->type( in(MemNode::ValueIn) );
2511 if( t3 == Type::TOP ) return Type::TOP;
2512 return Type::MEMORY;
2513 }
2515 //------------------------------Identity---------------------------------------
2516 // Remove redundant stores:
2517 // Store(m, p, Load(m, p)) changes to m.
2518 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
2519 Node *StoreNode::Identity( PhaseTransform *phase ) {
2520 Node* mem = in(MemNode::Memory);
2521 Node* adr = in(MemNode::Address);
2522 Node* val = in(MemNode::ValueIn);
2524 // Load then Store? Then the Store is useless
2525 if (val->is_Load() &&
2526 val->in(MemNode::Address)->eqv_uncast(adr) &&
2527 val->in(MemNode::Memory )->eqv_uncast(mem) &&
2528 val->as_Load()->store_Opcode() == Opcode()) {
2529 return mem;
2530 }
2532 // Two stores in a row of the same value?
2533 if (mem->is_Store() &&
2534 mem->in(MemNode::Address)->eqv_uncast(adr) &&
2535 mem->in(MemNode::ValueIn)->eqv_uncast(val) &&
2536 mem->Opcode() == Opcode()) {
2537 return mem;
2538 }
2540 // Store of zero anywhere into a freshly-allocated object?
2541 // Then the store is useless.
2542 // (It must already have been captured by the InitializeNode.)
2543 if (ReduceFieldZeroing && phase->type(val)->is_zero_type()) {
2544 // a newly allocated object is already all-zeroes everywhere
2545 if (mem->is_Proj() && mem->in(0)->is_Allocate()) {
2546 return mem;
2547 }
2549 // the store may also apply to zero-bits in an earlier object
2550 Node* prev_mem = find_previous_store(phase);
2551 // Steps (a), (b): Walk past independent stores to find an exact match.
2552 if (prev_mem != NULL) {
2553 Node* prev_val = can_see_stored_value(prev_mem, phase);
2554 if (prev_val != NULL && phase->eqv(prev_val, val)) {
2555 // prev_val and val might differ by a cast; it would be good
2556 // to keep the more informative of the two.
2557 return mem;
2558 }
2559 }
2560 }
2562 return this;
2563 }
2565 //------------------------------match_edge-------------------------------------
2566 // Do we Match on this edge index or not? Match only memory & value
2567 uint StoreNode::match_edge(uint idx) const {
2568 return idx == MemNode::Address || idx == MemNode::ValueIn;
2569 }
2571 //------------------------------cmp--------------------------------------------
2572 // Do not common stores up together. They generally have to be split
2573 // back up anyways, so do not bother.
2574 uint StoreNode::cmp( const Node &n ) const {
2575 return (&n == this); // Always fail except on self
2576 }
2578 //------------------------------Ideal_masked_input-----------------------------
2579 // Check for a useless mask before a partial-word store
2580 // (StoreB ... (AndI valIn conIa) )
2581 // If (conIa & mask == mask) this simplifies to
2582 // (StoreB ... (valIn) )
2583 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
2584 Node *val = in(MemNode::ValueIn);
2585 if( val->Opcode() == Op_AndI ) {
2586 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2587 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
2588 set_req(MemNode::ValueIn, val->in(1));
2589 return this;
2590 }
2591 }
2592 return NULL;
2593 }
2596 //------------------------------Ideal_sign_extended_input----------------------
2597 // Check for useless sign-extension before a partial-word store
2598 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) )
2599 // If (conIL == conIR && conIR <= num_bits) this simplifies to
2600 // (StoreB ... (valIn) )
2601 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) {
2602 Node *val = in(MemNode::ValueIn);
2603 if( val->Opcode() == Op_RShiftI ) {
2604 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2605 if( t && t->is_con() && (t->get_con() <= num_bits) ) {
2606 Node *shl = val->in(1);
2607 if( shl->Opcode() == Op_LShiftI ) {
2608 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int();
2609 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) {
2610 set_req(MemNode::ValueIn, shl->in(1));
2611 return this;
2612 }
2613 }
2614 }
2615 }
2616 return NULL;
2617 }
2619 //------------------------------value_never_loaded-----------------------------------
2620 // Determine whether there are any possible loads of the value stored.
2621 // For simplicity, we actually check if there are any loads from the
2622 // address stored to, not just for loads of the value stored by this node.
2623 //
2624 bool StoreNode::value_never_loaded( PhaseTransform *phase) const {
2625 Node *adr = in(Address);
2626 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
2627 if (adr_oop == NULL)
2628 return false;
2629 if (!adr_oop->is_known_instance_field())
2630 return false; // if not a distinct instance, there may be aliases of the address
2631 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
2632 Node *use = adr->fast_out(i);
2633 int opc = use->Opcode();
2634 if (use->is_Load() || use->is_LoadStore()) {
2635 return false;
2636 }
2637 }
2638 return true;
2639 }
2641 //=============================================================================
2642 //------------------------------Ideal------------------------------------------
2643 // If the store is from an AND mask that leaves the low bits untouched, then
2644 // we can skip the AND operation. If the store is from a sign-extension
2645 // (a left shift, then right shift) we can skip both.
2646 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
2647 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
2648 if( progress != NULL ) return progress;
2650 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
2651 if( progress != NULL ) return progress;
2653 // Finally check the default case
2654 return StoreNode::Ideal(phase, can_reshape);
2655 }
2657 //=============================================================================
2658 //------------------------------Ideal------------------------------------------
2659 // If the store is from an AND mask that leaves the low bits untouched, then
2660 // we can skip the AND operation
2661 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
2662 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
2663 if( progress != NULL ) return progress;
2665 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
2666 if( progress != NULL ) return progress;
2668 // Finally check the default case
2669 return StoreNode::Ideal(phase, can_reshape);
2670 }
2672 //=============================================================================
2673 //------------------------------Identity---------------------------------------
2674 Node *StoreCMNode::Identity( PhaseTransform *phase ) {
2675 // No need to card mark when storing a null ptr
2676 Node* my_store = in(MemNode::OopStore);
2677 if (my_store->is_Store()) {
2678 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) );
2679 if( t1 == TypePtr::NULL_PTR ) {
2680 return in(MemNode::Memory);
2681 }
2682 }
2683 return this;
2684 }
2686 //=============================================================================
2687 //------------------------------Ideal---------------------------------------
2688 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){
2689 Node* progress = StoreNode::Ideal(phase, can_reshape);
2690 if (progress != NULL) return progress;
2692 Node* my_store = in(MemNode::OopStore);
2693 if (my_store->is_MergeMem()) {
2694 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx());
2695 set_req(MemNode::OopStore, mem);
2696 return this;
2697 }
2699 return NULL;
2700 }
2702 //------------------------------Value-----------------------------------------
2703 const Type *StoreCMNode::Value( PhaseTransform *phase ) const {
2704 // Either input is TOP ==> the result is TOP
2705 const Type *t = phase->type( in(MemNode::Memory) );
2706 if( t == Type::TOP ) return Type::TOP;
2707 t = phase->type( in(MemNode::Address) );
2708 if( t == Type::TOP ) return Type::TOP;
2709 t = phase->type( in(MemNode::ValueIn) );
2710 if( t == Type::TOP ) return Type::TOP;
2711 // If extra input is TOP ==> the result is TOP
2712 t = phase->type( in(MemNode::OopStore) );
2713 if( t == Type::TOP ) return Type::TOP;
2715 return StoreNode::Value( phase );
2716 }
2719 //=============================================================================
2720 //----------------------------------SCMemProjNode------------------------------
2721 const Type * SCMemProjNode::Value( PhaseTransform *phase ) const
2722 {
2723 return bottom_type();
2724 }
2726 //=============================================================================
2727 //----------------------------------LoadStoreNode------------------------------
2728 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required )
2729 : Node(required),
2730 _type(rt),
2731 _adr_type(at)
2732 {
2733 init_req(MemNode::Control, c );
2734 init_req(MemNode::Memory , mem);
2735 init_req(MemNode::Address, adr);
2736 init_req(MemNode::ValueIn, val);
2737 init_class_id(Class_LoadStore);
2738 }
2740 uint LoadStoreNode::ideal_reg() const {
2741 return _type->ideal_reg();
2742 }
2744 bool LoadStoreNode::result_not_used() const {
2745 for( DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++ ) {
2746 Node *x = fast_out(i);
2747 if (x->Opcode() == Op_SCMemProj) continue;
2748 return false;
2749 }
2750 return true;
2751 }
2753 uint LoadStoreNode::size_of() const { return sizeof(*this); }
2755 //=============================================================================
2756 //----------------------------------LoadStoreConditionalNode--------------------
2757 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, NULL, TypeInt::BOOL, 5) {
2758 init_req(ExpectedIn, ex );
2759 }
2761 //=============================================================================
2762 //-------------------------------adr_type--------------------------------------
2763 // Do we Match on this edge index or not? Do not match memory
2764 const TypePtr* ClearArrayNode::adr_type() const {
2765 Node *adr = in(3);
2766 return MemNode::calculate_adr_type(adr->bottom_type());
2767 }
2769 //------------------------------match_edge-------------------------------------
2770 // Do we Match on this edge index or not? Do not match memory
2771 uint ClearArrayNode::match_edge(uint idx) const {
2772 return idx > 1;
2773 }
2775 //------------------------------Identity---------------------------------------
2776 // Clearing a zero length array does nothing
2777 Node *ClearArrayNode::Identity( PhaseTransform *phase ) {
2778 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
2779 }
2781 //------------------------------Idealize---------------------------------------
2782 // Clearing a short array is faster with stores
2783 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape){
2784 const int unit = BytesPerLong;
2785 const TypeX* t = phase->type(in(2))->isa_intptr_t();
2786 if (!t) return NULL;
2787 if (!t->is_con()) return NULL;
2788 intptr_t raw_count = t->get_con();
2789 intptr_t size = raw_count;
2790 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
2791 // Clearing nothing uses the Identity call.
2792 // Negative clears are possible on dead ClearArrays
2793 // (see jck test stmt114.stmt11402.val).
2794 if (size <= 0 || size % unit != 0) return NULL;
2795 intptr_t count = size / unit;
2796 // Length too long; use fast hardware clear
2797 if (size > Matcher::init_array_short_size) return NULL;
2798 Node *mem = in(1);
2799 if( phase->type(mem)==Type::TOP ) return NULL;
2800 Node *adr = in(3);
2801 const Type* at = phase->type(adr);
2802 if( at==Type::TOP ) return NULL;
2803 const TypePtr* atp = at->isa_ptr();
2804 // adjust atp to be the correct array element address type
2805 if (atp == NULL) atp = TypePtr::BOTTOM;
2806 else atp = atp->add_offset(Type::OffsetBot);
2807 // Get base for derived pointer purposes
2808 if( adr->Opcode() != Op_AddP ) Unimplemented();
2809 Node *base = adr->in(1);
2811 Node *zero = phase->makecon(TypeLong::ZERO);
2812 Node *off = phase->MakeConX(BytesPerLong);
2813 mem = new (phase->C) StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
2814 count--;
2815 while( count-- ) {
2816 mem = phase->transform(mem);
2817 adr = phase->transform(new (phase->C) AddPNode(base,adr,off));
2818 mem = new (phase->C) StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
2819 }
2820 return mem;
2821 }
2823 //----------------------------step_through----------------------------------
2824 // Return allocation input memory edge if it is different instance
2825 // or itself if it is the one we are looking for.
2826 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) {
2827 Node* n = *np;
2828 assert(n->is_ClearArray(), "sanity");
2829 intptr_t offset;
2830 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
2831 // This method is called only before Allocate nodes are expanded during
2832 // macro nodes expansion. Before that ClearArray nodes are only generated
2833 // in LibraryCallKit::generate_arraycopy() which follows allocations.
2834 assert(alloc != NULL, "should have allocation");
2835 if (alloc->_idx == instance_id) {
2836 // Can not bypass initialization of the instance we are looking for.
2837 return false;
2838 }
2839 // Otherwise skip it.
2840 InitializeNode* init = alloc->initialization();
2841 if (init != NULL)
2842 *np = init->in(TypeFunc::Memory);
2843 else
2844 *np = alloc->in(TypeFunc::Memory);
2845 return true;
2846 }
2848 //----------------------------clear_memory-------------------------------------
2849 // Generate code to initialize object storage to zero.
2850 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2851 intptr_t start_offset,
2852 Node* end_offset,
2853 PhaseGVN* phase) {
2854 Compile* C = phase->C;
2855 intptr_t offset = start_offset;
2857 int unit = BytesPerLong;
2858 if ((offset % unit) != 0) {
2859 Node* adr = new (C) AddPNode(dest, dest, phase->MakeConX(offset));
2860 adr = phase->transform(adr);
2861 const TypePtr* atp = TypeRawPtr::BOTTOM;
2862 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
2863 mem = phase->transform(mem);
2864 offset += BytesPerInt;
2865 }
2866 assert((offset % unit) == 0, "");
2868 // Initialize the remaining stuff, if any, with a ClearArray.
2869 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase);
2870 }
2872 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2873 Node* start_offset,
2874 Node* end_offset,
2875 PhaseGVN* phase) {
2876 if (start_offset == end_offset) {
2877 // nothing to do
2878 return mem;
2879 }
2881 Compile* C = phase->C;
2882 int unit = BytesPerLong;
2883 Node* zbase = start_offset;
2884 Node* zend = end_offset;
2886 // Scale to the unit required by the CPU:
2887 if (!Matcher::init_array_count_is_in_bytes) {
2888 Node* shift = phase->intcon(exact_log2(unit));
2889 zbase = phase->transform( new(C) URShiftXNode(zbase, shift) );
2890 zend = phase->transform( new(C) URShiftXNode(zend, shift) );
2891 }
2893 // Bulk clear double-words
2894 Node* zsize = phase->transform( new(C) SubXNode(zend, zbase) );
2895 Node* adr = phase->transform( new(C) AddPNode(dest, dest, start_offset) );
2896 mem = new (C) ClearArrayNode(ctl, mem, zsize, adr);
2897 return phase->transform(mem);
2898 }
2900 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2901 intptr_t start_offset,
2902 intptr_t end_offset,
2903 PhaseGVN* phase) {
2904 if (start_offset == end_offset) {
2905 // nothing to do
2906 return mem;
2907 }
2909 Compile* C = phase->C;
2910 assert((end_offset % BytesPerInt) == 0, "odd end offset");
2911 intptr_t done_offset = end_offset;
2912 if ((done_offset % BytesPerLong) != 0) {
2913 done_offset -= BytesPerInt;
2914 }
2915 if (done_offset > start_offset) {
2916 mem = clear_memory(ctl, mem, dest,
2917 start_offset, phase->MakeConX(done_offset), phase);
2918 }
2919 if (done_offset < end_offset) { // emit the final 32-bit store
2920 Node* adr = new (C) AddPNode(dest, dest, phase->MakeConX(done_offset));
2921 adr = phase->transform(adr);
2922 const TypePtr* atp = TypeRawPtr::BOTTOM;
2923 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
2924 mem = phase->transform(mem);
2925 done_offset += BytesPerInt;
2926 }
2927 assert(done_offset == end_offset, "");
2928 return mem;
2929 }
2931 //=============================================================================
2932 // Do not match memory edge.
2933 uint StrIntrinsicNode::match_edge(uint idx) const {
2934 return idx == 2 || idx == 3;
2935 }
2937 //------------------------------Ideal------------------------------------------
2938 // Return a node which is more "ideal" than the current node. Strip out
2939 // control copies
2940 Node *StrIntrinsicNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2941 if (remove_dead_region(phase, can_reshape)) return this;
2942 // Don't bother trying to transform a dead node
2943 if (in(0) && in(0)->is_top()) return NULL;
2945 if (can_reshape) {
2946 Node* mem = phase->transform(in(MemNode::Memory));
2947 // If transformed to a MergeMem, get the desired slice
2948 uint alias_idx = phase->C->get_alias_index(adr_type());
2949 mem = mem->is_MergeMem() ? mem->as_MergeMem()->memory_at(alias_idx) : mem;
2950 if (mem != in(MemNode::Memory)) {
2951 set_req(MemNode::Memory, mem);
2952 return this;
2953 }
2954 }
2955 return NULL;
2956 }
2958 //------------------------------Value------------------------------------------
2959 const Type *StrIntrinsicNode::Value( PhaseTransform *phase ) const {
2960 if (in(0) && phase->type(in(0)) == Type::TOP) return Type::TOP;
2961 return bottom_type();
2962 }
2964 //=============================================================================
2965 //------------------------------match_edge-------------------------------------
2966 // Do not match memory edge
2967 uint EncodeISOArrayNode::match_edge(uint idx) const {
2968 return idx == 2 || idx == 3; // EncodeISOArray src (Binary dst len)
2969 }
2971 //------------------------------Ideal------------------------------------------
2972 // Return a node which is more "ideal" than the current node. Strip out
2973 // control copies
2974 Node *EncodeISOArrayNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2975 return remove_dead_region(phase, can_reshape) ? this : NULL;
2976 }
2978 //------------------------------Value------------------------------------------
2979 const Type *EncodeISOArrayNode::Value(PhaseTransform *phase) const {
2980 if (in(0) && phase->type(in(0)) == Type::TOP) return Type::TOP;
2981 return bottom_type();
2982 }
2984 //=============================================================================
2985 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
2986 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)),
2987 _adr_type(C->get_adr_type(alias_idx))
2988 {
2989 init_class_id(Class_MemBar);
2990 Node* top = C->top();
2991 init_req(TypeFunc::I_O,top);
2992 init_req(TypeFunc::FramePtr,top);
2993 init_req(TypeFunc::ReturnAdr,top);
2994 if (precedent != NULL)
2995 init_req(TypeFunc::Parms, precedent);
2996 }
2998 //------------------------------cmp--------------------------------------------
2999 uint MemBarNode::hash() const { return NO_HASH; }
3000 uint MemBarNode::cmp( const Node &n ) const {
3001 return (&n == this); // Always fail except on self
3002 }
3004 //------------------------------make-------------------------------------------
3005 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
3006 switch (opcode) {
3007 case Op_MemBarAcquire: return new(C) MemBarAcquireNode(C, atp, pn);
3008 case Op_LoadFence: return new(C) LoadFenceNode(C, atp, pn);
3009 case Op_MemBarRelease: return new(C) MemBarReleaseNode(C, atp, pn);
3010 case Op_StoreFence: return new(C) StoreFenceNode(C, atp, pn);
3011 case Op_MemBarAcquireLock: return new(C) MemBarAcquireLockNode(C, atp, pn);
3012 case Op_MemBarReleaseLock: return new(C) MemBarReleaseLockNode(C, atp, pn);
3013 case Op_MemBarVolatile: return new(C) MemBarVolatileNode(C, atp, pn);
3014 case Op_MemBarCPUOrder: return new(C) MemBarCPUOrderNode(C, atp, pn);
3015 case Op_Initialize: return new(C) InitializeNode(C, atp, pn);
3016 case Op_MemBarStoreStore: return new(C) MemBarStoreStoreNode(C, atp, pn);
3017 default: ShouldNotReachHere(); return NULL;
3018 }
3019 }
3021 //------------------------------Ideal------------------------------------------
3022 // Return a node which is more "ideal" than the current node. Strip out
3023 // control copies
3024 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3025 if (remove_dead_region(phase, can_reshape)) return this;
3026 // Don't bother trying to transform a dead node
3027 if (in(0) && in(0)->is_top()) {
3028 return NULL;
3029 }
3031 // Eliminate volatile MemBars for scalar replaced objects.
3032 if (can_reshape && req() == (Precedent+1)) {
3033 bool eliminate = false;
3034 int opc = Opcode();
3035 if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) {
3036 // Volatile field loads and stores.
3037 Node* my_mem = in(MemBarNode::Precedent);
3038 // The MembarAquire may keep an unused LoadNode alive through the Precedent edge
3039 if ((my_mem != NULL) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) {
3040 // if the Precedent is a decodeN and its input (a Load) is used at more than one place,
3041 // replace this Precedent (decodeN) with the Load instead.
3042 if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1)) {
3043 Node* load_node = my_mem->in(1);
3044 set_req(MemBarNode::Precedent, load_node);
3045 phase->is_IterGVN()->_worklist.push(my_mem);
3046 my_mem = load_node;
3047 } else {
3048 assert(my_mem->unique_out() == this, "sanity");
3049 del_req(Precedent);
3050 phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later
3051 my_mem = NULL;
3052 }
3053 }
3054 if (my_mem != NULL && my_mem->is_Mem()) {
3055 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
3056 // Check for scalar replaced object reference.
3057 if( t_oop != NULL && t_oop->is_known_instance_field() &&
3058 t_oop->offset() != Type::OffsetBot &&
3059 t_oop->offset() != Type::OffsetTop) {
3060 eliminate = true;
3061 }
3062 }
3063 } else if (opc == Op_MemBarRelease) {
3064 // Final field stores.
3065 Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent), phase);
3066 if ((alloc != NULL) && alloc->is_Allocate() &&
3067 alloc->as_Allocate()->_is_non_escaping) {
3068 // The allocated object does not escape.
3069 eliminate = true;
3070 }
3071 }
3072 if (eliminate) {
3073 // Replace MemBar projections by its inputs.
3074 PhaseIterGVN* igvn = phase->is_IterGVN();
3075 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
3076 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
3077 // Must return either the original node (now dead) or a new node
3078 // (Do not return a top here, since that would break the uniqueness of top.)
3079 return new (phase->C) ConINode(TypeInt::ZERO);
3080 }
3081 }
3082 return NULL;
3083 }
3085 //------------------------------Value------------------------------------------
3086 const Type *MemBarNode::Value( PhaseTransform *phase ) const {
3087 if( !in(0) ) return Type::TOP;
3088 if( phase->type(in(0)) == Type::TOP )
3089 return Type::TOP;
3090 return TypeTuple::MEMBAR;
3091 }
3093 //------------------------------match------------------------------------------
3094 // Construct projections for memory.
3095 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) {
3096 switch (proj->_con) {
3097 case TypeFunc::Control:
3098 case TypeFunc::Memory:
3099 return new (m->C) MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
3100 }
3101 ShouldNotReachHere();
3102 return NULL;
3103 }
3105 //===========================InitializeNode====================================
3106 // SUMMARY:
3107 // This node acts as a memory barrier on raw memory, after some raw stores.
3108 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
3109 // The Initialize can 'capture' suitably constrained stores as raw inits.
3110 // It can coalesce related raw stores into larger units (called 'tiles').
3111 // It can avoid zeroing new storage for memory units which have raw inits.
3112 // At macro-expansion, it is marked 'complete', and does not optimize further.
3113 //
3114 // EXAMPLE:
3115 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
3116 // ctl = incoming control; mem* = incoming memory
3117 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
3118 // First allocate uninitialized memory and fill in the header:
3119 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
3120 // ctl := alloc.Control; mem* := alloc.Memory*
3121 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
3122 // Then initialize to zero the non-header parts of the raw memory block:
3123 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
3124 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
3125 // After the initialize node executes, the object is ready for service:
3126 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
3127 // Suppose its body is immediately initialized as {1,2}:
3128 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3129 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3130 // mem.SLICE(#short[*]) := store2
3131 //
3132 // DETAILS:
3133 // An InitializeNode collects and isolates object initialization after
3134 // an AllocateNode and before the next possible safepoint. As a
3135 // memory barrier (MemBarNode), it keeps critical stores from drifting
3136 // down past any safepoint or any publication of the allocation.
3137 // Before this barrier, a newly-allocated object may have uninitialized bits.
3138 // After this barrier, it may be treated as a real oop, and GC is allowed.
3139 //
3140 // The semantics of the InitializeNode include an implicit zeroing of
3141 // the new object from object header to the end of the object.
3142 // (The object header and end are determined by the AllocateNode.)
3143 //
3144 // Certain stores may be added as direct inputs to the InitializeNode.
3145 // These stores must update raw memory, and they must be to addresses
3146 // derived from the raw address produced by AllocateNode, and with
3147 // a constant offset. They must be ordered by increasing offset.
3148 // The first one is at in(RawStores), the last at in(req()-1).
3149 // Unlike most memory operations, they are not linked in a chain,
3150 // but are displayed in parallel as users of the rawmem output of
3151 // the allocation.
3152 //
3153 // (See comments in InitializeNode::capture_store, which continue
3154 // the example given above.)
3155 //
3156 // When the associated Allocate is macro-expanded, the InitializeNode
3157 // may be rewritten to optimize collected stores. A ClearArrayNode
3158 // may also be created at that point to represent any required zeroing.
3159 // The InitializeNode is then marked 'complete', prohibiting further
3160 // capturing of nearby memory operations.
3161 //
3162 // During macro-expansion, all captured initializations which store
3163 // constant values of 32 bits or smaller are coalesced (if advantageous)
3164 // into larger 'tiles' 32 or 64 bits. This allows an object to be
3165 // initialized in fewer memory operations. Memory words which are
3166 // covered by neither tiles nor non-constant stores are pre-zeroed
3167 // by explicit stores of zero. (The code shape happens to do all
3168 // zeroing first, then all other stores, with both sequences occurring
3169 // in order of ascending offsets.)
3170 //
3171 // Alternatively, code may be inserted between an AllocateNode and its
3172 // InitializeNode, to perform arbitrary initialization of the new object.
3173 // E.g., the object copying intrinsics insert complex data transfers here.
3174 // The initialization must then be marked as 'complete' disable the
3175 // built-in zeroing semantics and the collection of initializing stores.
3176 //
3177 // While an InitializeNode is incomplete, reads from the memory state
3178 // produced by it are optimizable if they match the control edge and
3179 // new oop address associated with the allocation/initialization.
3180 // They return a stored value (if the offset matches) or else zero.
3181 // A write to the memory state, if it matches control and address,
3182 // and if it is to a constant offset, may be 'captured' by the
3183 // InitializeNode. It is cloned as a raw memory operation and rewired
3184 // inside the initialization, to the raw oop produced by the allocation.
3185 // Operations on addresses which are provably distinct (e.g., to
3186 // other AllocateNodes) are allowed to bypass the initialization.
3187 //
3188 // The effect of all this is to consolidate object initialization
3189 // (both arrays and non-arrays, both piecewise and bulk) into a
3190 // single location, where it can be optimized as a unit.
3191 //
3192 // Only stores with an offset less than TrackedInitializationLimit words
3193 // will be considered for capture by an InitializeNode. This puts a
3194 // reasonable limit on the complexity of optimized initializations.
3196 //---------------------------InitializeNode------------------------------------
3197 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
3198 : _is_complete(Incomplete), _does_not_escape(false),
3199 MemBarNode(C, adr_type, rawoop)
3200 {
3201 init_class_id(Class_Initialize);
3203 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
3204 assert(in(RawAddress) == rawoop, "proper init");
3205 // Note: allocation() can be NULL, for secondary initialization barriers
3206 }
3208 // Since this node is not matched, it will be processed by the
3209 // register allocator. Declare that there are no constraints
3210 // on the allocation of the RawAddress edge.
3211 const RegMask &InitializeNode::in_RegMask(uint idx) const {
3212 // This edge should be set to top, by the set_complete. But be conservative.
3213 if (idx == InitializeNode::RawAddress)
3214 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
3215 return RegMask::Empty;
3216 }
3218 Node* InitializeNode::memory(uint alias_idx) {
3219 Node* mem = in(Memory);
3220 if (mem->is_MergeMem()) {
3221 return mem->as_MergeMem()->memory_at(alias_idx);
3222 } else {
3223 // incoming raw memory is not split
3224 return mem;
3225 }
3226 }
3228 bool InitializeNode::is_non_zero() {
3229 if (is_complete()) return false;
3230 remove_extra_zeroes();
3231 return (req() > RawStores);
3232 }
3234 void InitializeNode::set_complete(PhaseGVN* phase) {
3235 assert(!is_complete(), "caller responsibility");
3236 _is_complete = Complete;
3238 // After this node is complete, it contains a bunch of
3239 // raw-memory initializations. There is no need for
3240 // it to have anything to do with non-raw memory effects.
3241 // Therefore, tell all non-raw users to re-optimize themselves,
3242 // after skipping the memory effects of this initialization.
3243 PhaseIterGVN* igvn = phase->is_IterGVN();
3244 if (igvn) igvn->add_users_to_worklist(this);
3245 }
3247 // convenience function
3248 // return false if the init contains any stores already
3249 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
3250 InitializeNode* init = initialization();
3251 if (init == NULL || init->is_complete()) return false;
3252 init->remove_extra_zeroes();
3253 // for now, if this allocation has already collected any inits, bail:
3254 if (init->is_non_zero()) return false;
3255 init->set_complete(phase);
3256 return true;
3257 }
3259 void InitializeNode::remove_extra_zeroes() {
3260 if (req() == RawStores) return;
3261 Node* zmem = zero_memory();
3262 uint fill = RawStores;
3263 for (uint i = fill; i < req(); i++) {
3264 Node* n = in(i);
3265 if (n->is_top() || n == zmem) continue; // skip
3266 if (fill < i) set_req(fill, n); // compact
3267 ++fill;
3268 }
3269 // delete any empty spaces created:
3270 while (fill < req()) {
3271 del_req(fill);
3272 }
3273 }
3275 // Helper for remembering which stores go with which offsets.
3276 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) {
3277 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
3278 intptr_t offset = -1;
3279 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
3280 phase, offset);
3281 if (base == NULL) return -1; // something is dead,
3282 if (offset < 0) return -1; // dead, dead
3283 return offset;
3284 }
3286 // Helper for proving that an initialization expression is
3287 // "simple enough" to be folded into an object initialization.
3288 // Attempts to prove that a store's initial value 'n' can be captured
3289 // within the initialization without creating a vicious cycle, such as:
3290 // { Foo p = new Foo(); p.next = p; }
3291 // True for constants and parameters and small combinations thereof.
3292 bool InitializeNode::detect_init_independence(Node* n, int& count) {
3293 if (n == NULL) return true; // (can this really happen?)
3294 if (n->is_Proj()) n = n->in(0);
3295 if (n == this) return false; // found a cycle
3296 if (n->is_Con()) return true;
3297 if (n->is_Start()) return true; // params, etc., are OK
3298 if (n->is_Root()) return true; // even better
3300 Node* ctl = n->in(0);
3301 if (ctl != NULL && !ctl->is_top()) {
3302 if (ctl->is_Proj()) ctl = ctl->in(0);
3303 if (ctl == this) return false;
3305 // If we already know that the enclosing memory op is pinned right after
3306 // the init, then any control flow that the store has picked up
3307 // must have preceded the init, or else be equal to the init.
3308 // Even after loop optimizations (which might change control edges)
3309 // a store is never pinned *before* the availability of its inputs.
3310 if (!MemNode::all_controls_dominate(n, this))
3311 return false; // failed to prove a good control
3312 }
3314 // Check data edges for possible dependencies on 'this'.
3315 if ((count += 1) > 20) return false; // complexity limit
3316 for (uint i = 1; i < n->req(); i++) {
3317 Node* m = n->in(i);
3318 if (m == NULL || m == n || m->is_top()) continue;
3319 uint first_i = n->find_edge(m);
3320 if (i != first_i) continue; // process duplicate edge just once
3321 if (!detect_init_independence(m, count)) {
3322 return false;
3323 }
3324 }
3326 return true;
3327 }
3329 // Here are all the checks a Store must pass before it can be moved into
3330 // an initialization. Returns zero if a check fails.
3331 // On success, returns the (constant) offset to which the store applies,
3332 // within the initialized memory.
3333 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase, bool can_reshape) {
3334 const int FAIL = 0;
3335 if (st->is_unaligned_access()) {
3336 return FAIL;
3337 }
3338 if (st->req() != MemNode::ValueIn + 1)
3339 return FAIL; // an inscrutable StoreNode (card mark?)
3340 Node* ctl = st->in(MemNode::Control);
3341 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this))
3342 return FAIL; // must be unconditional after the initialization
3343 Node* mem = st->in(MemNode::Memory);
3344 if (!(mem->is_Proj() && mem->in(0) == this))
3345 return FAIL; // must not be preceded by other stores
3346 Node* adr = st->in(MemNode::Address);
3347 intptr_t offset;
3348 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
3349 if (alloc == NULL)
3350 return FAIL; // inscrutable address
3351 if (alloc != allocation())
3352 return FAIL; // wrong allocation! (store needs to float up)
3353 Node* val = st->in(MemNode::ValueIn);
3354 int complexity_count = 0;
3355 if (!detect_init_independence(val, complexity_count))
3356 return FAIL; // stored value must be 'simple enough'
3358 // The Store can be captured only if nothing after the allocation
3359 // and before the Store is using the memory location that the store
3360 // overwrites.
3361 bool failed = false;
3362 // If is_complete_with_arraycopy() is true the shape of the graph is
3363 // well defined and is safe so no need for extra checks.
3364 if (!is_complete_with_arraycopy()) {
3365 // We are going to look at each use of the memory state following
3366 // the allocation to make sure nothing reads the memory that the
3367 // Store writes.
3368 const TypePtr* t_adr = phase->type(adr)->isa_ptr();
3369 int alias_idx = phase->C->get_alias_index(t_adr);
3370 ResourceMark rm;
3371 Unique_Node_List mems;
3372 mems.push(mem);
3373 Node* unique_merge = NULL;
3374 for (uint next = 0; next < mems.size(); ++next) {
3375 Node *m = mems.at(next);
3376 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
3377 Node *n = m->fast_out(j);
3378 if (n->outcnt() == 0) {
3379 continue;
3380 }
3381 if (n == st) {
3382 continue;
3383 } else if (n->in(0) != NULL && n->in(0) != ctl) {
3384 // If the control of this use is different from the control
3385 // of the Store which is right after the InitializeNode then
3386 // this node cannot be between the InitializeNode and the
3387 // Store.
3388 continue;
3389 } else if (n->is_MergeMem()) {
3390 if (n->as_MergeMem()->memory_at(alias_idx) == m) {
3391 // We can hit a MergeMemNode (that will likely go away
3392 // later) that is a direct use of the memory state
3393 // following the InitializeNode on the same slice as the
3394 // store node that we'd like to capture. We need to check
3395 // the uses of the MergeMemNode.
3396 mems.push(n);
3397 }
3398 } else if (n->is_Mem()) {
3399 Node* other_adr = n->in(MemNode::Address);
3400 if (other_adr == adr) {
3401 failed = true;
3402 break;
3403 } else {
3404 const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr();
3405 if (other_t_adr != NULL) {
3406 int other_alias_idx = phase->C->get_alias_index(other_t_adr);
3407 if (other_alias_idx == alias_idx) {
3408 // A load from the same memory slice as the store right
3409 // after the InitializeNode. We check the control of the
3410 // object/array that is loaded from. If it's the same as
3411 // the store control then we cannot capture the store.
3412 assert(!n->is_Store(), "2 stores to same slice on same control?");
3413 Node* base = other_adr;
3414 assert(base->is_AddP(), err_msg_res("should be addp but is %s", base->Name()));
3415 base = base->in(AddPNode::Base);
3416 if (base != NULL) {
3417 base = base->uncast();
3418 if (base->is_Proj() && base->in(0) == alloc) {
3419 failed = true;
3420 break;
3421 }
3422 }
3423 }
3424 }
3425 }
3426 } else {
3427 failed = true;
3428 break;
3429 }
3430 }
3431 }
3432 }
3433 if (failed) {
3434 if (!can_reshape) {
3435 // We decided we couldn't capture the store during parsing. We
3436 // should try again during the next IGVN once the graph is
3437 // cleaner.
3438 phase->C->record_for_igvn(st);
3439 }
3440 return FAIL;
3441 }
3443 return offset; // success
3444 }
3446 // Find the captured store in(i) which corresponds to the range
3447 // [start..start+size) in the initialized object.
3448 // If there is one, return its index i. If there isn't, return the
3449 // negative of the index where it should be inserted.
3450 // Return 0 if the queried range overlaps an initialization boundary
3451 // or if dead code is encountered.
3452 // If size_in_bytes is zero, do not bother with overlap checks.
3453 int InitializeNode::captured_store_insertion_point(intptr_t start,
3454 int size_in_bytes,
3455 PhaseTransform* phase) {
3456 const int FAIL = 0, MAX_STORE = BytesPerLong;
3458 if (is_complete())
3459 return FAIL; // arraycopy got here first; punt
3461 assert(allocation() != NULL, "must be present");
3463 // no negatives, no header fields:
3464 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
3466 // after a certain size, we bail out on tracking all the stores:
3467 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3468 if (start >= ti_limit) return FAIL;
3470 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
3471 if (i >= limit) return -(int)i; // not found; here is where to put it
3473 Node* st = in(i);
3474 intptr_t st_off = get_store_offset(st, phase);
3475 if (st_off < 0) {
3476 if (st != zero_memory()) {
3477 return FAIL; // bail out if there is dead garbage
3478 }
3479 } else if (st_off > start) {
3480 // ...we are done, since stores are ordered
3481 if (st_off < start + size_in_bytes) {
3482 return FAIL; // the next store overlaps
3483 }
3484 return -(int)i; // not found; here is where to put it
3485 } else if (st_off < start) {
3486 if (size_in_bytes != 0 &&
3487 start < st_off + MAX_STORE &&
3488 start < st_off + st->as_Store()->memory_size()) {
3489 return FAIL; // the previous store overlaps
3490 }
3491 } else {
3492 if (size_in_bytes != 0 &&
3493 st->as_Store()->memory_size() != size_in_bytes) {
3494 return FAIL; // mismatched store size
3495 }
3496 return i;
3497 }
3499 ++i;
3500 }
3501 }
3503 // Look for a captured store which initializes at the offset 'start'
3504 // with the given size. If there is no such store, and no other
3505 // initialization interferes, then return zero_memory (the memory
3506 // projection of the AllocateNode).
3507 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
3508 PhaseTransform* phase) {
3509 assert(stores_are_sane(phase), "");
3510 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3511 if (i == 0) {
3512 return NULL; // something is dead
3513 } else if (i < 0) {
3514 return zero_memory(); // just primordial zero bits here
3515 } else {
3516 Node* st = in(i); // here is the store at this position
3517 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
3518 return st;
3519 }
3520 }
3522 // Create, as a raw pointer, an address within my new object at 'offset'.
3523 Node* InitializeNode::make_raw_address(intptr_t offset,
3524 PhaseTransform* phase) {
3525 Node* addr = in(RawAddress);
3526 if (offset != 0) {
3527 Compile* C = phase->C;
3528 addr = phase->transform( new (C) AddPNode(C->top(), addr,
3529 phase->MakeConX(offset)) );
3530 }
3531 return addr;
3532 }
3534 // Clone the given store, converting it into a raw store
3535 // initializing a field or element of my new object.
3536 // Caller is responsible for retiring the original store,
3537 // with subsume_node or the like.
3538 //
3539 // From the example above InitializeNode::InitializeNode,
3540 // here are the old stores to be captured:
3541 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3542 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3543 //
3544 // Here is the changed code; note the extra edges on init:
3545 // alloc = (Allocate ...)
3546 // rawoop = alloc.RawAddress
3547 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
3548 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
3549 // init = (Initialize alloc.Control alloc.Memory rawoop
3550 // rawstore1 rawstore2)
3551 //
3552 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
3553 PhaseTransform* phase, bool can_reshape) {
3554 assert(stores_are_sane(phase), "");
3556 if (start < 0) return NULL;
3557 assert(can_capture_store(st, phase, can_reshape) == start, "sanity");
3559 Compile* C = phase->C;
3560 int size_in_bytes = st->memory_size();
3561 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3562 if (i == 0) return NULL; // bail out
3563 Node* prev_mem = NULL; // raw memory for the captured store
3564 if (i > 0) {
3565 prev_mem = in(i); // there is a pre-existing store under this one
3566 set_req(i, C->top()); // temporarily disconnect it
3567 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
3568 } else {
3569 i = -i; // no pre-existing store
3570 prev_mem = zero_memory(); // a slice of the newly allocated object
3571 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
3572 set_req(--i, C->top()); // reuse this edge; it has been folded away
3573 else
3574 ins_req(i, C->top()); // build a new edge
3575 }
3576 Node* new_st = st->clone();
3577 new_st->set_req(MemNode::Control, in(Control));
3578 new_st->set_req(MemNode::Memory, prev_mem);
3579 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
3580 new_st = phase->transform(new_st);
3582 // At this point, new_st might have swallowed a pre-existing store
3583 // at the same offset, or perhaps new_st might have disappeared,
3584 // if it redundantly stored the same value (or zero to fresh memory).
3586 // In any case, wire it in:
3587 set_req(i, new_st);
3589 // The caller may now kill the old guy.
3590 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
3591 assert(check_st == new_st || check_st == NULL, "must be findable");
3592 assert(!is_complete(), "");
3593 return new_st;
3594 }
3596 static bool store_constant(jlong* tiles, int num_tiles,
3597 intptr_t st_off, int st_size,
3598 jlong con) {
3599 if ((st_off & (st_size-1)) != 0)
3600 return false; // strange store offset (assume size==2**N)
3601 address addr = (address)tiles + st_off;
3602 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
3603 switch (st_size) {
3604 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
3605 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
3606 case sizeof(jint): *(jint*) addr = (jint) con; break;
3607 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
3608 default: return false; // strange store size (detect size!=2**N here)
3609 }
3610 return true; // return success to caller
3611 }
3613 // Coalesce subword constants into int constants and possibly
3614 // into long constants. The goal, if the CPU permits,
3615 // is to initialize the object with a small number of 64-bit tiles.
3616 // Also, convert floating-point constants to bit patterns.
3617 // Non-constants are not relevant to this pass.
3618 //
3619 // In terms of the running example on InitializeNode::InitializeNode
3620 // and InitializeNode::capture_store, here is the transformation
3621 // of rawstore1 and rawstore2 into rawstore12:
3622 // alloc = (Allocate ...)
3623 // rawoop = alloc.RawAddress
3624 // tile12 = 0x00010002
3625 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
3626 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
3627 //
3628 void
3629 InitializeNode::coalesce_subword_stores(intptr_t header_size,
3630 Node* size_in_bytes,
3631 PhaseGVN* phase) {
3632 Compile* C = phase->C;
3634 assert(stores_are_sane(phase), "");
3635 // Note: After this pass, they are not completely sane,
3636 // since there may be some overlaps.
3638 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
3640 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3641 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
3642 size_limit = MIN2(size_limit, ti_limit);
3643 size_limit = align_size_up(size_limit, BytesPerLong);
3644 int num_tiles = size_limit / BytesPerLong;
3646 // allocate space for the tile map:
3647 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
3648 jlong tiles_buf[small_len];
3649 Node* nodes_buf[small_len];
3650 jlong inits_buf[small_len];
3651 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
3652 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3653 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
3654 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
3655 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
3656 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3657 // tiles: exact bitwise model of all primitive constants
3658 // nodes: last constant-storing node subsumed into the tiles model
3659 // inits: which bytes (in each tile) are touched by any initializations
3661 //// Pass A: Fill in the tile model with any relevant stores.
3663 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
3664 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
3665 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
3666 Node* zmem = zero_memory(); // initially zero memory state
3667 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3668 Node* st = in(i);
3669 intptr_t st_off = get_store_offset(st, phase);
3671 // Figure out the store's offset and constant value:
3672 if (st_off < header_size) continue; //skip (ignore header)
3673 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
3674 int st_size = st->as_Store()->memory_size();
3675 if (st_off + st_size > size_limit) break;
3677 // Record which bytes are touched, whether by constant or not.
3678 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
3679 continue; // skip (strange store size)
3681 const Type* val = phase->type(st->in(MemNode::ValueIn));
3682 if (!val->singleton()) continue; //skip (non-con store)
3683 BasicType type = val->basic_type();
3685 jlong con = 0;
3686 switch (type) {
3687 case T_INT: con = val->is_int()->get_con(); break;
3688 case T_LONG: con = val->is_long()->get_con(); break;
3689 case T_FLOAT: con = jint_cast(val->getf()); break;
3690 case T_DOUBLE: con = jlong_cast(val->getd()); break;
3691 default: continue; //skip (odd store type)
3692 }
3694 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
3695 st->Opcode() == Op_StoreL) {
3696 continue; // This StoreL is already optimal.
3697 }
3699 // Store down the constant.
3700 store_constant(tiles, num_tiles, st_off, st_size, con);
3702 intptr_t j = st_off >> LogBytesPerLong;
3704 if (type == T_INT && st_size == BytesPerInt
3705 && (st_off & BytesPerInt) == BytesPerInt) {
3706 jlong lcon = tiles[j];
3707 if (!Matcher::isSimpleConstant64(lcon) &&
3708 st->Opcode() == Op_StoreI) {
3709 // This StoreI is already optimal by itself.
3710 jint* intcon = (jint*) &tiles[j];
3711 intcon[1] = 0; // undo the store_constant()
3713 // If the previous store is also optimal by itself, back up and
3714 // undo the action of the previous loop iteration... if we can.
3715 // But if we can't, just let the previous half take care of itself.
3716 st = nodes[j];
3717 st_off -= BytesPerInt;
3718 con = intcon[0];
3719 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) {
3720 assert(st_off >= header_size, "still ignoring header");
3721 assert(get_store_offset(st, phase) == st_off, "must be");
3722 assert(in(i-1) == zmem, "must be");
3723 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
3724 assert(con == tcon->is_int()->get_con(), "must be");
3725 // Undo the effects of the previous loop trip, which swallowed st:
3726 intcon[0] = 0; // undo store_constant()
3727 set_req(i-1, st); // undo set_req(i, zmem)
3728 nodes[j] = NULL; // undo nodes[j] = st
3729 --old_subword; // undo ++old_subword
3730 }
3731 continue; // This StoreI is already optimal.
3732 }
3733 }
3735 // This store is not needed.
3736 set_req(i, zmem);
3737 nodes[j] = st; // record for the moment
3738 if (st_size < BytesPerLong) // something has changed
3739 ++old_subword; // includes int/float, but who's counting...
3740 else ++old_long;
3741 }
3743 if ((old_subword + old_long) == 0)
3744 return; // nothing more to do
3746 //// Pass B: Convert any non-zero tiles into optimal constant stores.
3747 // Be sure to insert them before overlapping non-constant stores.
3748 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
3749 for (int j = 0; j < num_tiles; j++) {
3750 jlong con = tiles[j];
3751 jlong init = inits[j];
3752 if (con == 0) continue;
3753 jint con0, con1; // split the constant, address-wise
3754 jint init0, init1; // split the init map, address-wise
3755 { union { jlong con; jint intcon[2]; } u;
3756 u.con = con;
3757 con0 = u.intcon[0];
3758 con1 = u.intcon[1];
3759 u.con = init;
3760 init0 = u.intcon[0];
3761 init1 = u.intcon[1];
3762 }
3764 Node* old = nodes[j];
3765 assert(old != NULL, "need the prior store");
3766 intptr_t offset = (j * BytesPerLong);
3768 bool split = !Matcher::isSimpleConstant64(con);
3770 if (offset < header_size) {
3771 assert(offset + BytesPerInt >= header_size, "second int counts");
3772 assert(*(jint*)&tiles[j] == 0, "junk in header");
3773 split = true; // only the second word counts
3774 // Example: int a[] = { 42 ... }
3775 } else if (con0 == 0 && init0 == -1) {
3776 split = true; // first word is covered by full inits
3777 // Example: int a[] = { ... foo(), 42 ... }
3778 } else if (con1 == 0 && init1 == -1) {
3779 split = true; // second word is covered by full inits
3780 // Example: int a[] = { ... 42, foo() ... }
3781 }
3783 // Here's a case where init0 is neither 0 nor -1:
3784 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
3785 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
3786 // In this case the tile is not split; it is (jlong)42.
3787 // The big tile is stored down, and then the foo() value is inserted.
3788 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
3790 Node* ctl = old->in(MemNode::Control);
3791 Node* adr = make_raw_address(offset, phase);
3792 const TypePtr* atp = TypeRawPtr::BOTTOM;
3794 // One or two coalesced stores to plop down.
3795 Node* st[2];
3796 intptr_t off[2];
3797 int nst = 0;
3798 if (!split) {
3799 ++new_long;
3800 off[nst] = offset;
3801 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3802 phase->longcon(con), T_LONG, MemNode::unordered);
3803 } else {
3804 // Omit either if it is a zero.
3805 if (con0 != 0) {
3806 ++new_int;
3807 off[nst] = offset;
3808 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3809 phase->intcon(con0), T_INT, MemNode::unordered);
3810 }
3811 if (con1 != 0) {
3812 ++new_int;
3813 offset += BytesPerInt;
3814 adr = make_raw_address(offset, phase);
3815 off[nst] = offset;
3816 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3817 phase->intcon(con1), T_INT, MemNode::unordered);
3818 }
3819 }
3821 // Insert second store first, then the first before the second.
3822 // Insert each one just before any overlapping non-constant stores.
3823 while (nst > 0) {
3824 Node* st1 = st[--nst];
3825 C->copy_node_notes_to(st1, old);
3826 st1 = phase->transform(st1);
3827 offset = off[nst];
3828 assert(offset >= header_size, "do not smash header");
3829 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
3830 guarantee(ins_idx != 0, "must re-insert constant store");
3831 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
3832 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
3833 set_req(--ins_idx, st1);
3834 else
3835 ins_req(ins_idx, st1);
3836 }
3837 }
3839 if (PrintCompilation && WizardMode)
3840 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
3841 old_subword, old_long, new_int, new_long);
3842 if (C->log() != NULL)
3843 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
3844 old_subword, old_long, new_int, new_long);
3846 // Clean up any remaining occurrences of zmem:
3847 remove_extra_zeroes();
3848 }
3850 // Explore forward from in(start) to find the first fully initialized
3851 // word, and return its offset. Skip groups of subword stores which
3852 // together initialize full words. If in(start) is itself part of a
3853 // fully initialized word, return the offset of in(start). If there
3854 // are no following full-word stores, or if something is fishy, return
3855 // a negative value.
3856 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
3857 int int_map = 0;
3858 intptr_t int_map_off = 0;
3859 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
3861 for (uint i = start, limit = req(); i < limit; i++) {
3862 Node* st = in(i);
3864 intptr_t st_off = get_store_offset(st, phase);
3865 if (st_off < 0) break; // return conservative answer
3867 int st_size = st->as_Store()->memory_size();
3868 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
3869 return st_off; // we found a complete word init
3870 }
3872 // update the map:
3874 intptr_t this_int_off = align_size_down(st_off, BytesPerInt);
3875 if (this_int_off != int_map_off) {
3876 // reset the map:
3877 int_map = 0;
3878 int_map_off = this_int_off;
3879 }
3881 int subword_off = st_off - this_int_off;
3882 int_map |= right_n_bits(st_size) << subword_off;
3883 if ((int_map & FULL_MAP) == FULL_MAP) {
3884 return this_int_off; // we found a complete word init
3885 }
3887 // Did this store hit or cross the word boundary?
3888 intptr_t next_int_off = align_size_down(st_off + st_size, BytesPerInt);
3889 if (next_int_off == this_int_off + BytesPerInt) {
3890 // We passed the current int, without fully initializing it.
3891 int_map_off = next_int_off;
3892 int_map >>= BytesPerInt;
3893 } else if (next_int_off > this_int_off + BytesPerInt) {
3894 // We passed the current and next int.
3895 return this_int_off + BytesPerInt;
3896 }
3897 }
3899 return -1;
3900 }
3903 // Called when the associated AllocateNode is expanded into CFG.
3904 // At this point, we may perform additional optimizations.
3905 // Linearize the stores by ascending offset, to make memory
3906 // activity as coherent as possible.
3907 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
3908 intptr_t header_size,
3909 Node* size_in_bytes,
3910 PhaseGVN* phase) {
3911 assert(!is_complete(), "not already complete");
3912 assert(stores_are_sane(phase), "");
3913 assert(allocation() != NULL, "must be present");
3915 remove_extra_zeroes();
3917 if (ReduceFieldZeroing || ReduceBulkZeroing)
3918 // reduce instruction count for common initialization patterns
3919 coalesce_subword_stores(header_size, size_in_bytes, phase);
3921 Node* zmem = zero_memory(); // initially zero memory state
3922 Node* inits = zmem; // accumulating a linearized chain of inits
3923 #ifdef ASSERT
3924 intptr_t first_offset = allocation()->minimum_header_size();
3925 intptr_t last_init_off = first_offset; // previous init offset
3926 intptr_t last_init_end = first_offset; // previous init offset+size
3927 intptr_t last_tile_end = first_offset; // previous tile offset+size
3928 #endif
3929 intptr_t zeroes_done = header_size;
3931 bool do_zeroing = true; // we might give up if inits are very sparse
3932 int big_init_gaps = 0; // how many large gaps have we seen?
3934 if (ZeroTLAB) do_zeroing = false;
3935 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
3937 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3938 Node* st = in(i);
3939 intptr_t st_off = get_store_offset(st, phase);
3940 if (st_off < 0)
3941 break; // unknown junk in the inits
3942 if (st->in(MemNode::Memory) != zmem)
3943 break; // complicated store chains somehow in list
3945 int st_size = st->as_Store()->memory_size();
3946 intptr_t next_init_off = st_off + st_size;
3948 if (do_zeroing && zeroes_done < next_init_off) {
3949 // See if this store needs a zero before it or under it.
3950 intptr_t zeroes_needed = st_off;
3952 if (st_size < BytesPerInt) {
3953 // Look for subword stores which only partially initialize words.
3954 // If we find some, we must lay down some word-level zeroes first,
3955 // underneath the subword stores.
3956 //
3957 // Examples:
3958 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
3959 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
3960 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
3961 //
3962 // Note: coalesce_subword_stores may have already done this,
3963 // if it was prompted by constant non-zero subword initializers.
3964 // But this case can still arise with non-constant stores.
3966 intptr_t next_full_store = find_next_fullword_store(i, phase);
3968 // In the examples above:
3969 // in(i) p q r s x y z
3970 // st_off 12 13 14 15 12 13 14
3971 // st_size 1 1 1 1 1 1 1
3972 // next_full_s. 12 16 16 16 16 16 16
3973 // z's_done 12 16 16 16 12 16 12
3974 // z's_needed 12 16 16 16 16 16 16
3975 // zsize 0 0 0 0 4 0 4
3976 if (next_full_store < 0) {
3977 // Conservative tack: Zero to end of current word.
3978 zeroes_needed = align_size_up(zeroes_needed, BytesPerInt);
3979 } else {
3980 // Zero to beginning of next fully initialized word.
3981 // Or, don't zero at all, if we are already in that word.
3982 assert(next_full_store >= zeroes_needed, "must go forward");
3983 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
3984 zeroes_needed = next_full_store;
3985 }
3986 }
3988 if (zeroes_needed > zeroes_done) {
3989 intptr_t zsize = zeroes_needed - zeroes_done;
3990 // Do some incremental zeroing on rawmem, in parallel with inits.
3991 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3992 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3993 zeroes_done, zeroes_needed,
3994 phase);
3995 zeroes_done = zeroes_needed;
3996 if (zsize > Matcher::init_array_short_size && ++big_init_gaps > 2)
3997 do_zeroing = false; // leave the hole, next time
3998 }
3999 }
4001 // Collect the store and move on:
4002 st->set_req(MemNode::Memory, inits);
4003 inits = st; // put it on the linearized chain
4004 set_req(i, zmem); // unhook from previous position
4006 if (zeroes_done == st_off)
4007 zeroes_done = next_init_off;
4009 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
4011 #ifdef ASSERT
4012 // Various order invariants. Weaker than stores_are_sane because
4013 // a large constant tile can be filled in by smaller non-constant stores.
4014 assert(st_off >= last_init_off, "inits do not reverse");
4015 last_init_off = st_off;
4016 const Type* val = NULL;
4017 if (st_size >= BytesPerInt &&
4018 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
4019 (int)val->basic_type() < (int)T_OBJECT) {
4020 assert(st_off >= last_tile_end, "tiles do not overlap");
4021 assert(st_off >= last_init_end, "tiles do not overwrite inits");
4022 last_tile_end = MAX2(last_tile_end, next_init_off);
4023 } else {
4024 intptr_t st_tile_end = align_size_up(next_init_off, BytesPerLong);
4025 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
4026 assert(st_off >= last_init_end, "inits do not overlap");
4027 last_init_end = next_init_off; // it's a non-tile
4028 }
4029 #endif //ASSERT
4030 }
4032 remove_extra_zeroes(); // clear out all the zmems left over
4033 add_req(inits);
4035 if (!ZeroTLAB) {
4036 // If anything remains to be zeroed, zero it all now.
4037 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
4038 // if it is the last unused 4 bytes of an instance, forget about it
4039 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
4040 if (zeroes_done + BytesPerLong >= size_limit) {
4041 AllocateNode* alloc = allocation();
4042 assert(alloc != NULL, "must be present");
4043 if (alloc != NULL && alloc->Opcode() == Op_Allocate) {
4044 Node* klass_node = alloc->in(AllocateNode::KlassNode);
4045 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass();
4046 if (zeroes_done == k->layout_helper())
4047 zeroes_done = size_limit;
4048 }
4049 }
4050 if (zeroes_done < size_limit) {
4051 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
4052 zeroes_done, size_in_bytes, phase);
4053 }
4054 }
4056 set_complete(phase);
4057 return rawmem;
4058 }
4061 #ifdef ASSERT
4062 bool InitializeNode::stores_are_sane(PhaseTransform* phase) {
4063 if (is_complete())
4064 return true; // stores could be anything at this point
4065 assert(allocation() != NULL, "must be present");
4066 intptr_t last_off = allocation()->minimum_header_size();
4067 for (uint i = InitializeNode::RawStores; i < req(); i++) {
4068 Node* st = in(i);
4069 intptr_t st_off = get_store_offset(st, phase);
4070 if (st_off < 0) continue; // ignore dead garbage
4071 if (last_off > st_off) {
4072 tty->print_cr("*** bad store offset at %d: " INTX_FORMAT " > " INTX_FORMAT, i, last_off, st_off);
4073 this->dump(2);
4074 assert(false, "ascending store offsets");
4075 return false;
4076 }
4077 last_off = st_off + st->as_Store()->memory_size();
4078 }
4079 return true;
4080 }
4081 #endif //ASSERT
4086 //============================MergeMemNode=====================================
4087 //
4088 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
4089 // contributing store or call operations. Each contributor provides the memory
4090 // state for a particular "alias type" (see Compile::alias_type). For example,
4091 // if a MergeMem has an input X for alias category #6, then any memory reference
4092 // to alias category #6 may use X as its memory state input, as an exact equivalent
4093 // to using the MergeMem as a whole.
4094 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
4095 //
4096 // (Here, the <N> notation gives the index of the relevant adr_type.)
4097 //
4098 // In one special case (and more cases in the future), alias categories overlap.
4099 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
4100 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
4101 // it is exactly equivalent to that state W:
4102 // MergeMem(<Bot>: W) <==> W
4103 //
4104 // Usually, the merge has more than one input. In that case, where inputs
4105 // overlap (i.e., one is Bot), the narrower alias type determines the memory
4106 // state for that type, and the wider alias type (Bot) fills in everywhere else:
4107 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
4108 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
4109 //
4110 // A merge can take a "wide" memory state as one of its narrow inputs.
4111 // This simply means that the merge observes out only the relevant parts of
4112 // the wide input. That is, wide memory states arriving at narrow merge inputs
4113 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
4114 //
4115 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
4116 // and that memory slices "leak through":
4117 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
4118 //
4119 // But, in such a cascade, repeated memory slices can "block the leak":
4120 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
4121 //
4122 // In the last example, Y is not part of the combined memory state of the
4123 // outermost MergeMem. The system must, of course, prevent unschedulable
4124 // memory states from arising, so you can be sure that the state Y is somehow
4125 // a precursor to state Y'.
4126 //
4127 //
4128 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
4129 // of each MergeMemNode array are exactly the numerical alias indexes, including
4130 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
4131 // Compile::alias_type (and kin) produce and manage these indexes.
4132 //
4133 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
4134 // (Note that this provides quick access to the top node inside MergeMem methods,
4135 // without the need to reach out via TLS to Compile::current.)
4136 //
4137 // As a consequence of what was just described, a MergeMem that represents a full
4138 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
4139 // containing all alias categories.
4140 //
4141 // MergeMem nodes never (?) have control inputs, so in(0) is NULL.
4142 //
4143 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
4144 // a memory state for the alias type <N>, or else the top node, meaning that
4145 // there is no particular input for that alias type. Note that the length of
4146 // a MergeMem is variable, and may be extended at any time to accommodate new
4147 // memory states at larger alias indexes. When merges grow, they are of course
4148 // filled with "top" in the unused in() positions.
4149 //
4150 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
4151 // (Top was chosen because it works smoothly with passes like GCM.)
4152 //
4153 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
4154 // the type of random VM bits like TLS references.) Since it is always the
4155 // first non-Bot memory slice, some low-level loops use it to initialize an
4156 // index variable: for (i = AliasIdxRaw; i < req(); i++).
4157 //
4158 //
4159 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
4160 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
4161 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
4162 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
4163 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
4164 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
4165 //
4166 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
4167 // really that different from the other memory inputs. An abbreviation called
4168 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
4169 //
4170 //
4171 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
4172 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
4173 // that "emerges though" the base memory will be marked as excluding the alias types
4174 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
4175 //
4176 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
4177 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
4178 //
4179 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
4180 // (It is currently unimplemented.) As you can see, the resulting merge is
4181 // actually a disjoint union of memory states, rather than an overlay.
4182 //
4184 //------------------------------MergeMemNode-----------------------------------
4185 Node* MergeMemNode::make_empty_memory() {
4186 Node* empty_memory = (Node*) Compile::current()->top();
4187 assert(empty_memory->is_top(), "correct sentinel identity");
4188 return empty_memory;
4189 }
4191 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
4192 init_class_id(Class_MergeMem);
4193 // all inputs are nullified in Node::Node(int)
4194 // set_input(0, NULL); // no control input
4196 // Initialize the edges uniformly to top, for starters.
4197 Node* empty_mem = make_empty_memory();
4198 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
4199 init_req(i,empty_mem);
4200 }
4201 assert(empty_memory() == empty_mem, "");
4203 if( new_base != NULL && new_base->is_MergeMem() ) {
4204 MergeMemNode* mdef = new_base->as_MergeMem();
4205 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
4206 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
4207 mms.set_memory(mms.memory2());
4208 }
4209 assert(base_memory() == mdef->base_memory(), "");
4210 } else {
4211 set_base_memory(new_base);
4212 }
4213 }
4215 // Make a new, untransformed MergeMem with the same base as 'mem'.
4216 // If mem is itself a MergeMem, populate the result with the same edges.
4217 MergeMemNode* MergeMemNode::make(Compile* C, Node* mem) {
4218 return new(C) MergeMemNode(mem);
4219 }
4221 //------------------------------cmp--------------------------------------------
4222 uint MergeMemNode::hash() const { return NO_HASH; }
4223 uint MergeMemNode::cmp( const Node &n ) const {
4224 return (&n == this); // Always fail except on self
4225 }
4227 //------------------------------Identity---------------------------------------
4228 Node* MergeMemNode::Identity(PhaseTransform *phase) {
4229 // Identity if this merge point does not record any interesting memory
4230 // disambiguations.
4231 Node* base_mem = base_memory();
4232 Node* empty_mem = empty_memory();
4233 if (base_mem != empty_mem) { // Memory path is not dead?
4234 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4235 Node* mem = in(i);
4236 if (mem != empty_mem && mem != base_mem) {
4237 return this; // Many memory splits; no change
4238 }
4239 }
4240 }
4241 return base_mem; // No memory splits; ID on the one true input
4242 }
4244 //------------------------------Ideal------------------------------------------
4245 // This method is invoked recursively on chains of MergeMem nodes
4246 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4247 // Remove chain'd MergeMems
4248 //
4249 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
4250 // relative to the "in(Bot)". Since we are patching both at the same time,
4251 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
4252 // but rewrite each "in(i)" relative to the new "in(Bot)".
4253 Node *progress = NULL;
4256 Node* old_base = base_memory();
4257 Node* empty_mem = empty_memory();
4258 if (old_base == empty_mem)
4259 return NULL; // Dead memory path.
4261 MergeMemNode* old_mbase;
4262 if (old_base != NULL && old_base->is_MergeMem())
4263 old_mbase = old_base->as_MergeMem();
4264 else
4265 old_mbase = NULL;
4266 Node* new_base = old_base;
4268 // simplify stacked MergeMems in base memory
4269 if (old_mbase) new_base = old_mbase->base_memory();
4271 // the base memory might contribute new slices beyond my req()
4272 if (old_mbase) grow_to_match(old_mbase);
4274 // Look carefully at the base node if it is a phi.
4275 PhiNode* phi_base;
4276 if (new_base != NULL && new_base->is_Phi())
4277 phi_base = new_base->as_Phi();
4278 else
4279 phi_base = NULL;
4281 Node* phi_reg = NULL;
4282 uint phi_len = (uint)-1;
4283 if (phi_base != NULL && !phi_base->is_copy()) {
4284 // do not examine phi if degraded to a copy
4285 phi_reg = phi_base->region();
4286 phi_len = phi_base->req();
4287 // see if the phi is unfinished
4288 for (uint i = 1; i < phi_len; i++) {
4289 if (phi_base->in(i) == NULL) {
4290 // incomplete phi; do not look at it yet!
4291 phi_reg = NULL;
4292 phi_len = (uint)-1;
4293 break;
4294 }
4295 }
4296 }
4298 // Note: We do not call verify_sparse on entry, because inputs
4299 // can normalize to the base_memory via subsume_node or similar
4300 // mechanisms. This method repairs that damage.
4302 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
4304 // Look at each slice.
4305 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4306 Node* old_in = in(i);
4307 // calculate the old memory value
4308 Node* old_mem = old_in;
4309 if (old_mem == empty_mem) old_mem = old_base;
4310 assert(old_mem == memory_at(i), "");
4312 // maybe update (reslice) the old memory value
4314 // simplify stacked MergeMems
4315 Node* new_mem = old_mem;
4316 MergeMemNode* old_mmem;
4317 if (old_mem != NULL && old_mem->is_MergeMem())
4318 old_mmem = old_mem->as_MergeMem();
4319 else
4320 old_mmem = NULL;
4321 if (old_mmem == this) {
4322 // This can happen if loops break up and safepoints disappear.
4323 // A merge of BotPtr (default) with a RawPtr memory derived from a
4324 // safepoint can be rewritten to a merge of the same BotPtr with
4325 // the BotPtr phi coming into the loop. If that phi disappears
4326 // also, we can end up with a self-loop of the mergemem.
4327 // In general, if loops degenerate and memory effects disappear,
4328 // a mergemem can be left looking at itself. This simply means
4329 // that the mergemem's default should be used, since there is
4330 // no longer any apparent effect on this slice.
4331 // Note: If a memory slice is a MergeMem cycle, it is unreachable
4332 // from start. Update the input to TOP.
4333 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
4334 }
4335 else if (old_mmem != NULL) {
4336 new_mem = old_mmem->memory_at(i);
4337 }
4338 // else preceding memory was not a MergeMem
4340 // replace equivalent phis (unfortunately, they do not GVN together)
4341 if (new_mem != NULL && new_mem != new_base &&
4342 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) {
4343 if (new_mem->is_Phi()) {
4344 PhiNode* phi_mem = new_mem->as_Phi();
4345 for (uint i = 1; i < phi_len; i++) {
4346 if (phi_base->in(i) != phi_mem->in(i)) {
4347 phi_mem = NULL;
4348 break;
4349 }
4350 }
4351 if (phi_mem != NULL) {
4352 // equivalent phi nodes; revert to the def
4353 new_mem = new_base;
4354 }
4355 }
4356 }
4358 // maybe store down a new value
4359 Node* new_in = new_mem;
4360 if (new_in == new_base) new_in = empty_mem;
4362 if (new_in != old_in) {
4363 // Warning: Do not combine this "if" with the previous "if"
4364 // A memory slice might have be be rewritten even if it is semantically
4365 // unchanged, if the base_memory value has changed.
4366 set_req(i, new_in);
4367 progress = this; // Report progress
4368 }
4369 }
4371 if (new_base != old_base) {
4372 set_req(Compile::AliasIdxBot, new_base);
4373 // Don't use set_base_memory(new_base), because we need to update du.
4374 assert(base_memory() == new_base, "");
4375 progress = this;
4376 }
4378 if( base_memory() == this ) {
4379 // a self cycle indicates this memory path is dead
4380 set_req(Compile::AliasIdxBot, empty_mem);
4381 }
4383 // Resolve external cycles by calling Ideal on a MergeMem base_memory
4384 // Recursion must occur after the self cycle check above
4385 if( base_memory()->is_MergeMem() ) {
4386 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
4387 Node *m = phase->transform(new_mbase); // Rollup any cycles
4388 if( m != NULL && (m->is_top() ||
4389 m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem) ) {
4390 // propagate rollup of dead cycle to self
4391 set_req(Compile::AliasIdxBot, empty_mem);
4392 }
4393 }
4395 if( base_memory() == empty_mem ) {
4396 progress = this;
4397 // Cut inputs during Parse phase only.
4398 // During Optimize phase a dead MergeMem node will be subsumed by Top.
4399 if( !can_reshape ) {
4400 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4401 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
4402 }
4403 }
4404 }
4406 if( !progress && base_memory()->is_Phi() && can_reshape ) {
4407 // Check if PhiNode::Ideal's "Split phis through memory merges"
4408 // transform should be attempted. Look for this->phi->this cycle.
4409 uint merge_width = req();
4410 if (merge_width > Compile::AliasIdxRaw) {
4411 PhiNode* phi = base_memory()->as_Phi();
4412 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
4413 if (phi->in(i) == this) {
4414 phase->is_IterGVN()->_worklist.push(phi);
4415 break;
4416 }
4417 }
4418 }
4419 }
4421 assert(progress || verify_sparse(), "please, no dups of base");
4422 return progress;
4423 }
4425 //-------------------------set_base_memory-------------------------------------
4426 void MergeMemNode::set_base_memory(Node *new_base) {
4427 Node* empty_mem = empty_memory();
4428 set_req(Compile::AliasIdxBot, new_base);
4429 assert(memory_at(req()) == new_base, "must set default memory");
4430 // Clear out other occurrences of new_base:
4431 if (new_base != empty_mem) {
4432 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4433 if (in(i) == new_base) set_req(i, empty_mem);
4434 }
4435 }
4436 }
4438 //------------------------------out_RegMask------------------------------------
4439 const RegMask &MergeMemNode::out_RegMask() const {
4440 return RegMask::Empty;
4441 }
4443 //------------------------------dump_spec--------------------------------------
4444 #ifndef PRODUCT
4445 void MergeMemNode::dump_spec(outputStream *st) const {
4446 st->print(" {");
4447 Node* base_mem = base_memory();
4448 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
4449 Node* mem = memory_at(i);
4450 if (mem == base_mem) { st->print(" -"); continue; }
4451 st->print( " N%d:", mem->_idx );
4452 Compile::current()->get_adr_type(i)->dump_on(st);
4453 }
4454 st->print(" }");
4455 }
4456 #endif // !PRODUCT
4459 #ifdef ASSERT
4460 static bool might_be_same(Node* a, Node* b) {
4461 if (a == b) return true;
4462 if (!(a->is_Phi() || b->is_Phi())) return false;
4463 // phis shift around during optimization
4464 return true; // pretty stupid...
4465 }
4467 // verify a narrow slice (either incoming or outgoing)
4468 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
4469 if (!VerifyAliases) return; // don't bother to verify unless requested
4470 if (is_error_reported()) return; // muzzle asserts when debugging an error
4471 if (Node::in_dump()) return; // muzzle asserts when printing
4472 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
4473 assert(n != NULL, "");
4474 // Elide intervening MergeMem's
4475 while (n->is_MergeMem()) {
4476 n = n->as_MergeMem()->memory_at(alias_idx);
4477 }
4478 Compile* C = Compile::current();
4479 const TypePtr* n_adr_type = n->adr_type();
4480 if (n == m->empty_memory()) {
4481 // Implicit copy of base_memory()
4482 } else if (n_adr_type != TypePtr::BOTTOM) {
4483 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type");
4484 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
4485 } else {
4486 // A few places like make_runtime_call "know" that VM calls are narrow,
4487 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
4488 bool expected_wide_mem = false;
4489 if (n == m->base_memory()) {
4490 expected_wide_mem = true;
4491 } else if (alias_idx == Compile::AliasIdxRaw ||
4492 n == m->memory_at(Compile::AliasIdxRaw)) {
4493 expected_wide_mem = true;
4494 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
4495 // memory can "leak through" calls on channels that
4496 // are write-once. Allow this also.
4497 expected_wide_mem = true;
4498 }
4499 assert(expected_wide_mem, "expected narrow slice replacement");
4500 }
4501 }
4502 #else // !ASSERT
4503 #define verify_memory_slice(m,i,n) (void)(0) // PRODUCT version is no-op
4504 #endif
4507 //-----------------------------memory_at---------------------------------------
4508 Node* MergeMemNode::memory_at(uint alias_idx) const {
4509 assert(alias_idx >= Compile::AliasIdxRaw ||
4510 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0,
4511 "must avoid base_memory and AliasIdxTop");
4513 // Otherwise, it is a narrow slice.
4514 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
4515 Compile *C = Compile::current();
4516 if (is_empty_memory(n)) {
4517 // the array is sparse; empty slots are the "top" node
4518 n = base_memory();
4519 assert(Node::in_dump()
4520 || n == NULL || n->bottom_type() == Type::TOP
4521 || n->adr_type() == NULL // address is TOP
4522 || n->adr_type() == TypePtr::BOTTOM
4523 || n->adr_type() == TypeRawPtr::BOTTOM
4524 || Compile::current()->AliasLevel() == 0,
4525 "must be a wide memory");
4526 // AliasLevel == 0 if we are organizing the memory states manually.
4527 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
4528 } else {
4529 // make sure the stored slice is sane
4530 #ifdef ASSERT
4531 if (is_error_reported() || Node::in_dump()) {
4532 } else if (might_be_same(n, base_memory())) {
4533 // Give it a pass: It is a mostly harmless repetition of the base.
4534 // This can arise normally from node subsumption during optimization.
4535 } else {
4536 verify_memory_slice(this, alias_idx, n);
4537 }
4538 #endif
4539 }
4540 return n;
4541 }
4543 //---------------------------set_memory_at-------------------------------------
4544 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
4545 verify_memory_slice(this, alias_idx, n);
4546 Node* empty_mem = empty_memory();
4547 if (n == base_memory()) n = empty_mem; // collapse default
4548 uint need_req = alias_idx+1;
4549 if (req() < need_req) {
4550 if (n == empty_mem) return; // already the default, so do not grow me
4551 // grow the sparse array
4552 do {
4553 add_req(empty_mem);
4554 } while (req() < need_req);
4555 }
4556 set_req( alias_idx, n );
4557 }
4561 //--------------------------iteration_setup------------------------------------
4562 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
4563 if (other != NULL) {
4564 grow_to_match(other);
4565 // invariant: the finite support of mm2 is within mm->req()
4566 #ifdef ASSERT
4567 for (uint i = req(); i < other->req(); i++) {
4568 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
4569 }
4570 #endif
4571 }
4572 // Replace spurious copies of base_memory by top.
4573 Node* base_mem = base_memory();
4574 if (base_mem != NULL && !base_mem->is_top()) {
4575 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
4576 if (in(i) == base_mem)
4577 set_req(i, empty_memory());
4578 }
4579 }
4580 }
4582 //---------------------------grow_to_match-------------------------------------
4583 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
4584 Node* empty_mem = empty_memory();
4585 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
4586 // look for the finite support of the other memory
4587 for (uint i = other->req(); --i >= req(); ) {
4588 if (other->in(i) != empty_mem) {
4589 uint new_len = i+1;
4590 while (req() < new_len) add_req(empty_mem);
4591 break;
4592 }
4593 }
4594 }
4596 //---------------------------verify_sparse-------------------------------------
4597 #ifndef PRODUCT
4598 bool MergeMemNode::verify_sparse() const {
4599 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
4600 Node* base_mem = base_memory();
4601 // The following can happen in degenerate cases, since empty==top.
4602 if (is_empty_memory(base_mem)) return true;
4603 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4604 assert(in(i) != NULL, "sane slice");
4605 if (in(i) == base_mem) return false; // should have been the sentinel value!
4606 }
4607 return true;
4608 }
4610 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
4611 Node* n;
4612 n = mm->in(idx);
4613 if (mem == n) return true; // might be empty_memory()
4614 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
4615 if (mem == n) return true;
4616 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) {
4617 if (mem == n) return true;
4618 if (n == NULL) break;
4619 }
4620 return false;
4621 }
4622 #endif // !PRODUCT