1 /*
2 * Copyright (c) 1997, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/systemDictionary.hpp"
27 #include "compiler/compileLog.hpp"
28 #include "memory/allocation.inline.hpp"
29 #include "oops/objArrayKlass.hpp"
30 #include "opto/addnode.hpp"
31 #include "opto/arraycopynode.hpp"
32 #include "opto/cfgnode.hpp"
33 #include "opto/compile.hpp"
34 #include "opto/connode.hpp"
35 #include "opto/convertnode.hpp"
36 #include "opto/loopnode.hpp"
37 #include "opto/machnode.hpp"
38 #include "opto/matcher.hpp"
39 #include "opto/memnode.hpp"
40 #include "opto/mulnode.hpp"
41 #include "opto/narrowptrnode.hpp"
42 #include "opto/phaseX.hpp"
43 #include "opto/regmask.hpp"
44 #include "utilities/copy.hpp"
45
46 // Portions of code courtesy of Clifford Click
47
48 // Optimization - Graph Style
49
50 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st);
51
52 //=============================================================================
53 uint MemNode::size_of() const { return sizeof(*this); }
54
55 const TypePtr *MemNode::adr_type() const {
56 Node* adr = in(Address);
57 if (adr == NULL) return NULL; // node is dead
58 const TypePtr* cross_check = NULL;
59 DEBUG_ONLY(cross_check = _adr_type);
60 return calculate_adr_type(adr->bottom_type(), cross_check);
61 }
62
63 #ifndef PRODUCT
64 void MemNode::dump_spec(outputStream *st) const {
65 if (in(Address) == NULL) return; // node is dead
66 #ifndef ASSERT
67 // fake the missing field
68 const TypePtr* _adr_type = NULL;
69 if (in(Address) != NULL)
70 _adr_type = in(Address)->bottom_type()->isa_ptr();
71 #endif
72 dump_adr_type(this, _adr_type, st);
73
74 Compile* C = Compile::current();
75 if( C->alias_type(_adr_type)->is_volatile() )
76 st->print(" Volatile!");
77 }
78
79 void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) {
80 st->print(" @");
81 if (adr_type == NULL) {
82 st->print("NULL");
83 } else {
84 adr_type->dump_on(st);
85 Compile* C = Compile::current();
86 Compile::AliasType* atp = NULL;
87 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type);
88 if (atp == NULL)
89 st->print(", idx=?\?;");
90 else if (atp->index() == Compile::AliasIdxBot)
91 st->print(", idx=Bot;");
92 else if (atp->index() == Compile::AliasIdxTop)
93 st->print(", idx=Top;");
94 else if (atp->index() == Compile::AliasIdxRaw)
95 st->print(", idx=Raw;");
96 else {
97 ciField* field = atp->field();
98 if (field) {
99 st->print(", name=");
100 field->print_name_on(st);
101 }
102 st->print(", idx=%d;", atp->index());
103 }
104 }
105 }
106
107 extern void print_alias_types();
108
109 #endif
110
111 static bool membar_for_arraycopy_helper(const TypeOopPtr *t_oop, MergeMemNode* mm, PhaseTransform *phase) {
112 if (mm->memory_at(Compile::AliasIdxRaw)->is_Proj()) {
113 Node* n = mm->memory_at(Compile::AliasIdxRaw)->in(0);
114 if ((n->is_ArrayCopy() && n->as_ArrayCopy()->may_modify(t_oop, phase)) ||
115 (n->is_CallLeaf() && n->as_CallLeaf()->may_modify(t_oop, phase))) {
116 return true;
117 }
118 }
119 return false;
120 }
121
122 static bool membar_for_arraycopy(const TypeOopPtr *t_oop, MemBarNode* mb, PhaseTransform *phase) {
123 Node* mem = mb->in(TypeFunc::Memory);
124 if (mem->is_MergeMem()) {
125 return membar_for_arraycopy_helper(t_oop, mem->as_MergeMem(), phase);
126 } else if (mem->is_Phi()) {
127 // after macro expansion of an ArrayCopyNode we may have a Phi
128 for (uint i = 1; i < mem->req(); i++) {
129 if (mem->in(i) != NULL && mem->in(i)->is_MergeMem() && membar_for_arraycopy_helper(t_oop, mem->in(i)->as_MergeMem(), phase)) {
130 return true;
131 }
132 }
133 }
134 return false;
135 }
136
137 Node *MemNode::optimize_simple_memory_chain(Node *mchain, const TypeOopPtr *t_oop, Node *load, PhaseGVN *phase) {
138 assert((t_oop != NULL), "sanity");
139 bool is_instance = t_oop->is_known_instance_field();
140 bool is_boxed_value_load = t_oop->is_ptr_to_boxed_value() &&
141 (load != NULL) && load->is_Load() &&
142 (phase->is_IterGVN() != NULL);
143 if (!(is_instance || is_boxed_value_load))
144 return mchain; // don't try to optimize non-instance types
145 uint instance_id = t_oop->instance_id();
146 Node *start_mem = phase->C->start()->proj_out(TypeFunc::Memory);
147 Node *prev = NULL;
148 Node *result = mchain;
149 while (prev != result) {
150 prev = result;
151 if (result == start_mem)
152 break; // hit one of our sentinels
153 // skip over a call which does not affect this memory slice
154 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {
155 Node *proj_in = result->in(0);
156 if (proj_in->is_Allocate() && proj_in->_idx == instance_id) {
157 break; // hit one of our sentinels
158 } else if (proj_in->is_Call()) {
159 // ArrayCopyNodes processed here as well
160 CallNode *call = proj_in->as_Call();
161 if (!call->may_modify(t_oop, phase)) { // returns false for instances
162 result = call->in(TypeFunc::Memory);
163 }
164 } else if (proj_in->is_Initialize()) {
165 AllocateNode* alloc = proj_in->as_Initialize()->allocation();
166 // Stop if this is the initialization for the object instance which
167 // contains this memory slice, otherwise skip over it.
168 if ((alloc == NULL) || (alloc->_idx == instance_id)) {
169 break;
170 }
171 if (is_instance) {
172 result = proj_in->in(TypeFunc::Memory);
173 } else if (is_boxed_value_load) {
174 Node* klass = alloc->in(AllocateNode::KlassNode);
175 const TypeKlassPtr* tklass = phase->type(klass)->is_klassptr();
176 if (tklass->klass_is_exact() && !tklass->klass()->equals(t_oop->klass())) {
177 result = proj_in->in(TypeFunc::Memory); // not related allocation
178 }
179 }
180 } else if (proj_in->is_MemBar()) {
181 if (membar_for_arraycopy(t_oop, proj_in->as_MemBar(), phase)) {
182 break;
183 }
184 result = proj_in->in(TypeFunc::Memory);
185 } else {
186 assert(false, "unexpected projection");
187 }
188 } else if (result->is_ClearArray()) {
189 if (!is_instance || !ClearArrayNode::step_through(&result, instance_id, phase)) {
190 // Can not bypass initialization of the instance
191 // we are looking for.
192 break;
193 }
194 // Otherwise skip it (the call updated 'result' value).
195 } else if (result->is_MergeMem()) {
196 result = step_through_mergemem(phase, result->as_MergeMem(), t_oop, NULL, tty);
197 }
198 }
199 return result;
200 }
201
202 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, Node *load, PhaseGVN *phase) {
203 const TypeOopPtr* t_oop = t_adr->isa_oopptr();
204 if (t_oop == NULL)
205 return mchain; // don't try to optimize non-oop types
206 Node* result = optimize_simple_memory_chain(mchain, t_oop, load, phase);
207 bool is_instance = t_oop->is_known_instance_field();
208 PhaseIterGVN *igvn = phase->is_IterGVN();
209 if (is_instance && igvn != NULL && result->is_Phi()) {
210 PhiNode *mphi = result->as_Phi();
211 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
212 const TypePtr *t = mphi->adr_type();
213 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
214 t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
215 t->is_oopptr()->cast_to_exactness(true)
216 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
217 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop) {
218 // clone the Phi with our address type
219 result = mphi->split_out_instance(t_adr, igvn);
220 } else {
221 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain");
222 }
223 }
224 return result;
225 }
226
227 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) {
228 uint alias_idx = phase->C->get_alias_index(tp);
229 Node *mem = mmem;
230 #ifdef ASSERT
231 {
232 // Check that current type is consistent with the alias index used during graph construction
233 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
234 bool consistent = adr_check == NULL || adr_check->empty() ||
235 phase->C->must_alias(adr_check, alias_idx );
236 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
237 if( !consistent && adr_check != NULL && !adr_check->empty() &&
238 tp->isa_aryptr() && tp->offset() == Type::OffsetBot &&
239 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot &&
240 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() ||
241 adr_check->offset() == oopDesc::klass_offset_in_bytes() ||
242 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) {
243 // don't assert if it is dead code.
244 consistent = true;
245 }
246 if( !consistent ) {
247 st->print("alias_idx==%d, adr_check==", alias_idx);
248 if( adr_check == NULL ) {
249 st->print("NULL");
250 } else {
251 adr_check->dump();
252 }
253 st->cr();
254 print_alias_types();
255 assert(consistent, "adr_check must match alias idx");
256 }
257 }
258 #endif
259 // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally
260 // means an array I have not precisely typed yet. Do not do any
261 // alias stuff with it any time soon.
262 const TypeOopPtr *toop = tp->isa_oopptr();
263 if( tp->base() != Type::AnyPtr &&
264 !(toop &&
265 toop->klass() != NULL &&
266 toop->klass()->is_java_lang_Object() &&
267 toop->offset() == Type::OffsetBot) ) {
268 // compress paths and change unreachable cycles to TOP
269 // If not, we can update the input infinitely along a MergeMem cycle
270 // Equivalent code in PhiNode::Ideal
271 Node* m = phase->transform(mmem);
272 // If transformed to a MergeMem, get the desired slice
273 // Otherwise the returned node represents memory for every slice
274 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
275 // Update input if it is progress over what we have now
276 }
277 return mem;
278 }
279
280 //--------------------------Ideal_common---------------------------------------
281 // Look for degenerate control and memory inputs. Bypass MergeMem inputs.
282 // Unhook non-raw memories from complete (macro-expanded) initializations.
283 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
284 // If our control input is a dead region, kill all below the region
285 Node *ctl = in(MemNode::Control);
286 if (ctl && remove_dead_region(phase, can_reshape))
287 return this;
288 ctl = in(MemNode::Control);
289 // Don't bother trying to transform a dead node
290 if (ctl && ctl->is_top()) return NodeSentinel;
291
292 PhaseIterGVN *igvn = phase->is_IterGVN();
293 // Wait if control on the worklist.
294 if (ctl && can_reshape && igvn != NULL) {
295 Node* bol = NULL;
296 Node* cmp = NULL;
297 if (ctl->in(0)->is_If()) {
298 assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity");
299 bol = ctl->in(0)->in(1);
300 if (bol->is_Bool())
301 cmp = ctl->in(0)->in(1)->in(1);
302 }
303 if (igvn->_worklist.member(ctl) ||
304 (bol != NULL && igvn->_worklist.member(bol)) ||
305 (cmp != NULL && igvn->_worklist.member(cmp)) ) {
306 // This control path may be dead.
307 // Delay this memory node transformation until the control is processed.
308 phase->is_IterGVN()->_worklist.push(this);
309 return NodeSentinel; // caller will return NULL
310 }
311 }
312 // Ignore if memory is dead, or self-loop
313 Node *mem = in(MemNode::Memory);
314 if (phase->type( mem ) == Type::TOP) return NodeSentinel; // caller will return NULL
315 assert(mem != this, "dead loop in MemNode::Ideal");
316
317 if (can_reshape && igvn != NULL && igvn->_worklist.member(mem)) {
318 // This memory slice may be dead.
319 // Delay this mem node transformation until the memory is processed.
320 phase->is_IterGVN()->_worklist.push(this);
321 return NodeSentinel; // caller will return NULL
322 }
323
324 Node *address = in(MemNode::Address);
325 const Type *t_adr = phase->type(address);
326 if (t_adr == Type::TOP) return NodeSentinel; // caller will return NULL
327
328 if (can_reshape && igvn != NULL &&
329 (igvn->_worklist.member(address) ||
330 igvn->_worklist.size() > 0 && (t_adr != adr_type())) ) {
331 // The address's base and type may change when the address is processed.
332 // Delay this mem node transformation until the address is processed.
333 phase->is_IterGVN()->_worklist.push(this);
334 return NodeSentinel; // caller will return NULL
335 }
336
337 // Do NOT remove or optimize the next lines: ensure a new alias index
338 // is allocated for an oop pointer type before Escape Analysis.
339 // Note: C++ will not remove it since the call has side effect.
340 if (t_adr->isa_oopptr()) {
341 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr());
342 }
343
344 Node* base = NULL;
345 if (address->is_AddP()) {
346 base = address->in(AddPNode::Base);
347 }
348 if (base != NULL && phase->type(base)->higher_equal(TypePtr::NULL_PTR) &&
349 !t_adr->isa_rawptr()) {
350 // Note: raw address has TOP base and top->higher_equal(TypePtr::NULL_PTR) is true.
351 // Skip this node optimization if its address has TOP base.
352 return NodeSentinel; // caller will return NULL
353 }
354
355 // Avoid independent memory operations
356 Node* old_mem = mem;
357
358 // The code which unhooks non-raw memories from complete (macro-expanded)
359 // initializations was removed. After macro-expansion all stores catched
360 // by Initialize node became raw stores and there is no information
361 // which memory slices they modify. So it is unsafe to move any memory
362 // operation above these stores. Also in most cases hooked non-raw memories
363 // were already unhooked by using information from detect_ptr_independence()
364 // and find_previous_store().
365
366 if (mem->is_MergeMem()) {
367 MergeMemNode* mmem = mem->as_MergeMem();
368 const TypePtr *tp = t_adr->is_ptr();
369
370 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
371 }
372
373 if (mem != old_mem) {
374 set_req(MemNode::Memory, mem);
375 if (can_reshape && old_mem->outcnt() == 0) {
376 igvn->_worklist.push(old_mem);
377 }
378 if (phase->type( mem ) == Type::TOP) return NodeSentinel;
379 return this;
380 }
381
382 // let the subclass continue analyzing...
383 return NULL;
384 }
385
386 // Helper function for proving some simple control dominations.
387 // Attempt to prove that all control inputs of 'dom' dominate 'sub'.
388 // Already assumes that 'dom' is available at 'sub', and that 'sub'
389 // is not a constant (dominated by the method's StartNode).
390 // Used by MemNode::find_previous_store to prove that the
391 // control input of a memory operation predates (dominates)
392 // an allocation it wants to look past.
393 bool MemNode::all_controls_dominate(Node* dom, Node* sub) {
394 if (dom == NULL || dom->is_top() || sub == NULL || sub->is_top())
395 return false; // Conservative answer for dead code
396
397 // Check 'dom'. Skip Proj and CatchProj nodes.
398 dom = dom->find_exact_control(dom);
399 if (dom == NULL || dom->is_top())
400 return false; // Conservative answer for dead code
401
402 if (dom == sub) {
403 // For the case when, for example, 'sub' is Initialize and the original
404 // 'dom' is Proj node of the 'sub'.
405 return false;
406 }
407
408 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub)
409 return true;
410
411 // 'dom' dominates 'sub' if its control edge and control edges
412 // of all its inputs dominate or equal to sub's control edge.
413
414 // Currently 'sub' is either Allocate, Initialize or Start nodes.
415 // Or Region for the check in LoadNode::Ideal();
416 // 'sub' should have sub->in(0) != NULL.
417 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() ||
418 sub->is_Region() || sub->is_Call(), "expecting only these nodes");
419
420 // Get control edge of 'sub'.
421 Node* orig_sub = sub;
422 sub = sub->find_exact_control(sub->in(0));
423 if (sub == NULL || sub->is_top())
424 return false; // Conservative answer for dead code
425
426 assert(sub->is_CFG(), "expecting control");
427
428 if (sub == dom)
429 return true;
430
431 if (sub->is_Start() || sub->is_Root())
432 return false;
433
434 {
435 // Check all control edges of 'dom'.
436
437 ResourceMark rm;
438 Arena* arena = Thread::current()->resource_area();
439 Node_List nlist(arena);
440 Unique_Node_List dom_list(arena);
441
442 dom_list.push(dom);
443 bool only_dominating_controls = false;
444
445 for (uint next = 0; next < dom_list.size(); next++) {
446 Node* n = dom_list.at(next);
447 if (n == orig_sub)
448 return false; // One of dom's inputs dominated by sub.
449 if (!n->is_CFG() && n->pinned()) {
450 // Check only own control edge for pinned non-control nodes.
451 n = n->find_exact_control(n->in(0));
452 if (n == NULL || n->is_top())
453 return false; // Conservative answer for dead code
454 assert(n->is_CFG(), "expecting control");
455 dom_list.push(n);
456 } else if (n->is_Con() || n->is_Start() || n->is_Root()) {
457 only_dominating_controls = true;
458 } else if (n->is_CFG()) {
459 if (n->dominates(sub, nlist))
460 only_dominating_controls = true;
461 else
462 return false;
463 } else {
464 // First, own control edge.
465 Node* m = n->find_exact_control(n->in(0));
466 if (m != NULL) {
467 if (m->is_top())
468 return false; // Conservative answer for dead code
469 dom_list.push(m);
470 }
471 // Now, the rest of edges.
472 uint cnt = n->req();
473 for (uint i = 1; i < cnt; i++) {
474 m = n->find_exact_control(n->in(i));
475 if (m == NULL || m->is_top())
476 continue;
477 dom_list.push(m);
478 }
479 }
480 }
481 return only_dominating_controls;
482 }
483 }
484
485 //---------------------detect_ptr_independence---------------------------------
486 // Used by MemNode::find_previous_store to prove that two base
487 // pointers are never equal.
488 // The pointers are accompanied by their associated allocations,
489 // if any, which have been previously discovered by the caller.
490 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
491 Node* p2, AllocateNode* a2,
492 PhaseTransform* phase) {
493 // Attempt to prove that these two pointers cannot be aliased.
494 // They may both manifestly be allocations, and they should differ.
495 // Or, if they are not both allocations, they can be distinct constants.
496 // Otherwise, one is an allocation and the other a pre-existing value.
497 if (a1 == NULL && a2 == NULL) { // neither an allocation
498 return (p1 != p2) && p1->is_Con() && p2->is_Con();
499 } else if (a1 != NULL && a2 != NULL) { // both allocations
500 return (a1 != a2);
501 } else if (a1 != NULL) { // one allocation a1
502 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.)
503 return all_controls_dominate(p2, a1);
504 } else { //(a2 != NULL) // one allocation a2
505 return all_controls_dominate(p1, a2);
506 }
507 return false;
508 }
509
510
511 // Find an arraycopy that must have set (can_see_stored_value=true) or
512 // could have set (can_see_stored_value=false) the value for this load
513 Node* LoadNode::find_previous_arraycopy(PhaseTransform* phase, Node* ld_alloc, Node*& mem, bool can_see_stored_value) const {
514 if (mem->is_Proj() && mem->in(0) != NULL && (mem->in(0)->Opcode() == Op_MemBarStoreStore ||
515 mem->in(0)->Opcode() == Op_MemBarCPUOrder)) {
516 Node* mb = mem->in(0);
517 if (mb->in(0) != NULL && mb->in(0)->is_Proj() &&
518 mb->in(0)->in(0) != NULL && mb->in(0)->in(0)->is_ArrayCopy()) {
519 ArrayCopyNode* ac = mb->in(0)->in(0)->as_ArrayCopy();
520 if (ac->is_clonebasic()) {
521 intptr_t offset;
522 AllocateNode* alloc = AllocateNode::Ideal_allocation(ac->in(ArrayCopyNode::Dest), phase, offset);
523 assert(alloc != NULL && alloc->initialization()->is_complete_with_arraycopy(), "broken allocation");
524 if (alloc == ld_alloc) {
525 return ac;
526 }
527 }
528 }
529 } else if (mem->is_Proj() && mem->in(0) != NULL && mem->in(0)->is_ArrayCopy()) {
530 ArrayCopyNode* ac = mem->in(0)->as_ArrayCopy();
531
532 if (ac->is_arraycopy_validated() ||
533 ac->is_copyof_validated() ||
534 ac->is_copyofrange_validated()) {
535 Node* ld_addp = in(MemNode::Address);
536 if (ld_addp->is_AddP()) {
537 Node* ld_base = ld_addp->in(AddPNode::Address);
538 Node* ld_offs = ld_addp->in(AddPNode::Offset);
539
540 Node* dest = ac->in(ArrayCopyNode::Dest);
541
542 if (dest == ld_base) {
543 Node* src_pos = ac->in(ArrayCopyNode::SrcPos);
544 Node* dest_pos = ac->in(ArrayCopyNode::DestPos);
545 Node* len = ac->in(ArrayCopyNode::Length);
546
547 const TypeInt *dest_pos_t = phase->type(dest_pos)->isa_int();
548 const TypeX *ld_offs_t = phase->type(ld_offs)->isa_intptr_t();
549 const TypeInt *len_t = phase->type(len)->isa_int();
550 const TypeAryPtr* ary_t = phase->type(dest)->isa_aryptr();
551
552 if (dest_pos_t != NULL && ld_offs_t != NULL && len_t != NULL && ary_t != NULL) {
553 BasicType ary_elem = ary_t->klass()->as_array_klass()->element_type()->basic_type();
554 uint header = arrayOopDesc::base_offset_in_bytes(ary_elem);
555 uint elemsize = type2aelembytes(ary_elem);
556
557 intptr_t dest_pos_plus_len_lo = (((intptr_t)dest_pos_t->_lo) + len_t->_lo) * elemsize + header;
558 intptr_t dest_pos_plus_len_hi = (((intptr_t)dest_pos_t->_hi) + len_t->_hi) * elemsize + header;
559 intptr_t dest_pos_lo = ((intptr_t)dest_pos_t->_lo) * elemsize + header;
560 intptr_t dest_pos_hi = ((intptr_t)dest_pos_t->_hi) * elemsize + header;
561
562 if (can_see_stored_value) {
563 if (ld_offs_t->_lo >= dest_pos_hi && ld_offs_t->_hi < dest_pos_plus_len_lo) {
564 return ac;
565 }
566 } else {
567 if (ld_offs_t->_hi < dest_pos_lo || ld_offs_t->_lo >= dest_pos_plus_len_hi) {
568 mem = ac->in(TypeFunc::Memory);
569 }
570 return ac;
571 }
572 }
573 }
574 }
575 }
576 }
577 return NULL;
578 }
579
580 // The logic for reordering loads and stores uses four steps:
581 // (a) Walk carefully past stores and initializations which we
582 // can prove are independent of this load.
583 // (b) Observe that the next memory state makes an exact match
584 // with self (load or store), and locate the relevant store.
585 // (c) Ensure that, if we were to wire self directly to the store,
586 // the optimizer would fold it up somehow.
587 // (d) Do the rewiring, and return, depending on some other part of
588 // the optimizer to fold up the load.
589 // This routine handles steps (a) and (b). Steps (c) and (d) are
590 // specific to loads and stores, so they are handled by the callers.
591 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.)
592 //
593 Node* MemNode::find_previous_store(PhaseTransform* phase) {
594 Node* ctrl = in(MemNode::Control);
595 Node* adr = in(MemNode::Address);
596 intptr_t offset = 0;
597 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
598 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase);
599
600 if (offset == Type::OffsetBot)
601 return NULL; // cannot unalias unless there are precise offsets
602
603 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr();
604
605 intptr_t size_in_bytes = memory_size();
606
607 Node* mem = in(MemNode::Memory); // start searching here...
608
609 int cnt = 50; // Cycle limiter
610 for (;;) { // While we can dance past unrelated stores...
611 if (--cnt < 0) break; // Caught in cycle or a complicated dance?
612
613 Node* prev = mem;
614 if (mem->is_Store()) {
615 Node* st_adr = mem->in(MemNode::Address);
616 intptr_t st_offset = 0;
617 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
618 if (st_base == NULL)
619 break; // inscrutable pointer
620 if (st_offset != offset && st_offset != Type::OffsetBot) {
621 const int MAX_STORE = BytesPerLong;
622 if (st_offset >= offset + size_in_bytes ||
623 st_offset <= offset - MAX_STORE ||
624 st_offset <= offset - mem->as_Store()->memory_size()) {
625 // Success: The offsets are provably independent.
626 // (You may ask, why not just test st_offset != offset and be done?
627 // The answer is that stores of different sizes can co-exist
628 // in the same sequence of RawMem effects. We sometimes initialize
629 // a whole 'tile' of array elements with a single jint or jlong.)
630 mem = mem->in(MemNode::Memory);
631 continue; // (a) advance through independent store memory
632 }
633 }
634 if (st_base != base &&
635 detect_ptr_independence(base, alloc,
636 st_base,
637 AllocateNode::Ideal_allocation(st_base, phase),
638 phase)) {
639 // Success: The bases are provably independent.
640 mem = mem->in(MemNode::Memory);
641 continue; // (a) advance through independent store memory
642 }
643
644 // (b) At this point, if the bases or offsets do not agree, we lose,
645 // since we have not managed to prove 'this' and 'mem' independent.
646 if (st_base == base && st_offset == offset) {
647 return mem; // let caller handle steps (c), (d)
648 }
649
650 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
651 InitializeNode* st_init = mem->in(0)->as_Initialize();
652 AllocateNode* st_alloc = st_init->allocation();
653 if (st_alloc == NULL)
654 break; // something degenerated
655 bool known_identical = false;
656 bool known_independent = false;
657 if (alloc == st_alloc)
658 known_identical = true;
659 else if (alloc != NULL)
660 known_independent = true;
661 else if (all_controls_dominate(this, st_alloc))
662 known_independent = true;
663
664 if (known_independent) {
665 // The bases are provably independent: Either they are
666 // manifestly distinct allocations, or else the control
667 // of this load dominates the store's allocation.
668 int alias_idx = phase->C->get_alias_index(adr_type());
669 if (alias_idx == Compile::AliasIdxRaw) {
670 mem = st_alloc->in(TypeFunc::Memory);
671 } else {
672 mem = st_init->memory(alias_idx);
673 }
674 continue; // (a) advance through independent store memory
675 }
676
677 // (b) at this point, if we are not looking at a store initializing
678 // the same allocation we are loading from, we lose.
679 if (known_identical) {
680 // From caller, can_see_stored_value will consult find_captured_store.
681 return mem; // let caller handle steps (c), (d)
682 }
683
684 } else if (find_previous_arraycopy(phase, alloc, mem, false) != NULL) {
685 if (prev != mem) {
686 // Found an arraycopy but it doesn't affect that load
687 continue;
688 }
689 // Found an arraycopy that may affect that load
690 return mem;
691 } else if (addr_t != NULL && addr_t->is_known_instance_field()) {
692 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
693 if (mem->is_Proj() && mem->in(0)->is_Call()) {
694 // ArrayCopyNodes processed here as well.
695 CallNode *call = mem->in(0)->as_Call();
696 if (!call->may_modify(addr_t, phase)) {
697 mem = call->in(TypeFunc::Memory);
698 continue; // (a) advance through independent call memory
699 }
700 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) {
701 if (membar_for_arraycopy(addr_t, mem->in(0)->as_MemBar(), phase)) {
702 break;
703 }
704 mem = mem->in(0)->in(TypeFunc::Memory);
705 continue; // (a) advance through independent MemBar memory
706 } else if (mem->is_ClearArray()) {
707 if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) {
708 // (the call updated 'mem' value)
709 continue; // (a) advance through independent allocation memory
710 } else {
711 // Can not bypass initialization of the instance
712 // we are looking for.
713 return mem;
714 }
715 } else if (mem->is_MergeMem()) {
716 int alias_idx = phase->C->get_alias_index(adr_type());
717 mem = mem->as_MergeMem()->memory_at(alias_idx);
718 continue; // (a) advance through independent MergeMem memory
719 }
720 }
721
722 // Unless there is an explicit 'continue', we must bail out here,
723 // because 'mem' is an inscrutable memory state (e.g., a call).
724 break;
725 }
726
727 return NULL; // bail out
728 }
729
730 //----------------------calculate_adr_type-------------------------------------
731 // Helper function. Notices when the given type of address hits top or bottom.
732 // Also, asserts a cross-check of the type against the expected address type.
733 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
734 if (t == Type::TOP) return NULL; // does not touch memory any more?
735 #ifdef PRODUCT
736 cross_check = NULL;
737 #else
738 if (!VerifyAliases || is_error_reported() || Node::in_dump()) cross_check = NULL;
739 #endif
740 const TypePtr* tp = t->isa_ptr();
741 if (tp == NULL) {
742 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
743 return TypePtr::BOTTOM; // touches lots of memory
744 } else {
745 #ifdef ASSERT
746 // %%%% [phh] We don't check the alias index if cross_check is
747 // TypeRawPtr::BOTTOM. Needs to be investigated.
748 if (cross_check != NULL &&
749 cross_check != TypePtr::BOTTOM &&
750 cross_check != TypeRawPtr::BOTTOM) {
751 // Recheck the alias index, to see if it has changed (due to a bug).
752 Compile* C = Compile::current();
753 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
754 "must stay in the original alias category");
755 // The type of the address must be contained in the adr_type,
756 // disregarding "null"-ness.
757 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
758 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
759 assert(cross_check->meet(tp_notnull) == cross_check->remove_speculative(),
760 "real address must not escape from expected memory type");
761 }
762 #endif
763 return tp;
764 }
765 }
766
767 //=============================================================================
768 // Should LoadNode::Ideal() attempt to remove control edges?
769 bool LoadNode::can_remove_control() const {
770 return true;
771 }
772 uint LoadNode::size_of() const { return sizeof(*this); }
773 uint LoadNode::cmp( const Node &n ) const
774 { return !Type::cmp( _type, ((LoadNode&)n)._type ); }
775 const Type *LoadNode::bottom_type() const { return _type; }
776 uint LoadNode::ideal_reg() const {
777 return _type->ideal_reg();
778 }
779
780 #ifndef PRODUCT
781 void LoadNode::dump_spec(outputStream *st) const {
782 MemNode::dump_spec(st);
783 if( !Verbose && !WizardMode ) {
784 // standard dump does this in Verbose and WizardMode
785 st->print(" #"); _type->dump_on(st);
786 }
787 if (!_depends_only_on_test) {
788 st->print(" (does not depend only on test)");
789 }
790 }
791 #endif
792
793 #ifdef ASSERT
794 //----------------------------is_immutable_value-------------------------------
795 // Helper function to allow a raw load without control edge for some cases
796 bool LoadNode::is_immutable_value(Node* adr) {
797 return (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() &&
798 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal &&
799 (adr->in(AddPNode::Offset)->find_intptr_t_con(-1) ==
800 in_bytes(JavaThread::osthread_offset())));
801 }
802 #endif
803
804 //----------------------------LoadNode::make-----------------------------------
805 // Polymorphic factory method:
806 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) {
807 Compile* C = gvn.C;
808
809 // sanity check the alias category against the created node type
810 assert(!(adr_type->isa_oopptr() &&
811 adr_type->offset() == oopDesc::klass_offset_in_bytes()),
812 "use LoadKlassNode instead");
813 assert(!(adr_type->isa_aryptr() &&
814 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
815 "use LoadRangeNode instead");
816 // Check control edge of raw loads
817 assert( ctl != NULL || C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
818 // oop will be recorded in oop map if load crosses safepoint
819 rt->isa_oopptr() || is_immutable_value(adr),
820 "raw memory operations should have control edge");
821 switch (bt) {
822 case T_BOOLEAN: return new LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency);
823 case T_BYTE: return new LoadBNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency);
824 case T_INT: return new LoadINode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency);
825 case T_CHAR: return new LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency);
826 case T_SHORT: return new LoadSNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency);
827 case T_LONG: return new LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency);
828 case T_FLOAT: return new LoadFNode (ctl, mem, adr, adr_type, rt, mo, control_dependency);
829 case T_DOUBLE: return new LoadDNode (ctl, mem, adr, adr_type, rt, mo, control_dependency);
830 case T_ADDRESS: return new LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency);
831 case T_OBJECT:
832 #ifdef _LP64
833 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
834 Node* load = gvn.transform(new LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo, control_dependency));
835 return new DecodeNNode(load, load->bottom_type()->make_ptr());
836 } else
837 #endif
838 {
839 assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop");
840 return new LoadPNode(ctl, mem, adr, adr_type, rt->is_oopptr(), mo, control_dependency);
841 }
842 }
843 ShouldNotReachHere();
844 return (LoadNode*)NULL;
845 }
846
847 LoadLNode* LoadLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo, ControlDependency control_dependency) {
848 bool require_atomic = true;
849 return new LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency, require_atomic);
850 }
851
852 LoadDNode* LoadDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo, ControlDependency control_dependency) {
853 bool require_atomic = true;
854 return new LoadDNode(ctl, mem, adr, adr_type, rt, mo, control_dependency, require_atomic);
855 }
856
857
858
859 //------------------------------hash-------------------------------------------
860 uint LoadNode::hash() const {
861 // unroll addition of interesting fields
862 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
863 }
864
865 static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) {
866 if ((atp != NULL) && (atp->index() >= Compile::AliasIdxRaw)) {
867 bool non_volatile = (atp->field() != NULL) && !atp->field()->is_volatile();
868 bool is_stable_ary = FoldStableValues &&
869 (tp != NULL) && (tp->isa_aryptr() != NULL) &&
870 tp->isa_aryptr()->is_stable();
871
872 return (eliminate_boxing && non_volatile) || is_stable_ary;
873 }
874
875 return false;
876 }
877
878 // Is the value loaded previously stored by an arraycopy? If so return
879 // a load node that reads from the source array so we may be able to
880 // optimize out the ArrayCopy node later.
881 Node* MemNode::can_see_arraycopy_value(Node* st, PhaseTransform* phase) const {
882 Node* ld_adr = in(MemNode::Address);
883 intptr_t ld_off = 0;
884 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
885 Node* ac = find_previous_arraycopy(phase, ld_alloc, st, true);
886 if (ac != NULL) {
887 assert(ac->is_ArrayCopy(), "what kind of node can this be?");
888 assert(is_Load(), "only for loads");
889
890 if (ac->as_ArrayCopy()->is_clonebasic()) {
891 assert(ld_alloc != NULL, "need an alloc");
892 Node* ld = clone();
893 Node* addp = in(MemNode::Address)->clone();
894 assert(addp->is_AddP(), "address must be addp");
895 assert(addp->in(AddPNode::Base) == ac->in(ArrayCopyNode::Dest)->in(AddPNode::Base), "strange pattern");
896 assert(addp->in(AddPNode::Address) == ac->in(ArrayCopyNode::Dest)->in(AddPNode::Address), "strange pattern");
897 addp->set_req(AddPNode::Base, ac->in(ArrayCopyNode::Src)->in(AddPNode::Base));
898 addp->set_req(AddPNode::Address, ac->in(ArrayCopyNode::Src)->in(AddPNode::Address));
899 ld->set_req(MemNode::Address, phase->transform(addp));
900 if (in(0) != NULL) {
901 assert(ld_alloc->in(0) != NULL, "alloc must have control");
902 ld->set_req(0, ld_alloc->in(0));
903 }
904 return ld;
905 } else {
906 Node* ld = clone();
907 Node* addp = in(MemNode::Address)->clone();
908 assert(addp->in(AddPNode::Base) == addp->in(AddPNode::Address), "should be");
909 addp->set_req(AddPNode::Base, ac->in(ArrayCopyNode::Src));
910 addp->set_req(AddPNode::Address, ac->in(ArrayCopyNode::Src));
911
912 const TypeAryPtr* ary_t = phase->type(in(MemNode::Address))->isa_aryptr();
913 BasicType ary_elem = ary_t->klass()->as_array_klass()->element_type()->basic_type();
914 uint header = arrayOopDesc::base_offset_in_bytes(ary_elem);
915 uint shift = exact_log2(type2aelembytes(ary_elem));
916
917 Node* diff = phase->transform(new SubINode(ac->in(ArrayCopyNode::SrcPos), ac->in(ArrayCopyNode::DestPos)));
918 #ifdef _LP64
919 diff = phase->transform(new ConvI2LNode(diff));
920 #endif
921 diff = phase->transform(new LShiftXNode(diff, phase->intcon(shift)));
922
923 Node* offset = phase->transform(new AddXNode(addp->in(AddPNode::Offset), diff));
924 addp->set_req(AddPNode::Offset, offset);
925 ld->set_req(MemNode::Address, phase->transform(addp));
926
927 if (in(0) != NULL) {
928 assert(ac->in(0) != NULL, "alloc must have control");
929 ld->set_req(0, ac->in(0));
930 }
931 return ld;
932 }
933 }
934 return NULL;
935 }
936
937
938 //---------------------------can_see_stored_value------------------------------
939 // This routine exists to make sure this set of tests is done the same
940 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
941 // will change the graph shape in a way which makes memory alive twice at the
942 // same time (uses the Oracle model of aliasing), then some
943 // LoadXNode::Identity will fold things back to the equivalence-class model
944 // of aliasing.
945 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const {
946 Node* ld_adr = in(MemNode::Address);
947 intptr_t ld_off = 0;
948 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
949 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
950 Compile::AliasType* atp = (tp != NULL) ? phase->C->alias_type(tp) : NULL;
951 // This is more general than load from boxing objects.
952 if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) {
953 uint alias_idx = atp->index();
954 bool final = !atp->is_rewritable();
955 Node* result = NULL;
956 Node* current = st;
957 // Skip through chains of MemBarNodes checking the MergeMems for
958 // new states for the slice of this load. Stop once any other
959 // kind of node is encountered. Loads from final memory can skip
960 // through any kind of MemBar but normal loads shouldn't skip
961 // through MemBarAcquire since the could allow them to move out of
962 // a synchronized region.
963 while (current->is_Proj()) {
964 int opc = current->in(0)->Opcode();
965 if ((final && (opc == Op_MemBarAcquire ||
966 opc == Op_MemBarAcquireLock ||
967 opc == Op_LoadFence)) ||
968 opc == Op_MemBarRelease ||
969 opc == Op_StoreFence ||
970 opc == Op_MemBarReleaseLock ||
971 opc == Op_MemBarStoreStore ||
972 opc == Op_MemBarCPUOrder) {
973 Node* mem = current->in(0)->in(TypeFunc::Memory);
974 if (mem->is_MergeMem()) {
975 MergeMemNode* merge = mem->as_MergeMem();
976 Node* new_st = merge->memory_at(alias_idx);
977 if (new_st == merge->base_memory()) {
978 // Keep searching
979 current = new_st;
980 continue;
981 }
982 // Save the new memory state for the slice and fall through
983 // to exit.
984 result = new_st;
985 }
986 }
987 break;
988 }
989 if (result != NULL) {
990 st = result;
991 }
992 }
993
994 // Loop around twice in the case Load -> Initialize -> Store.
995 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
996 for (int trip = 0; trip <= 1; trip++) {
997
998 if (st->is_Store()) {
999 Node* st_adr = st->in(MemNode::Address);
1000 if (!phase->eqv(st_adr, ld_adr)) {
1001 // Try harder before giving up... Match raw and non-raw pointers.
1002 intptr_t st_off = 0;
1003 AllocateNode* alloc = AllocateNode::Ideal_allocation(st_adr, phase, st_off);
1004 if (alloc == NULL) return NULL;
1005 if (alloc != ld_alloc) return NULL;
1006 if (ld_off != st_off) return NULL;
1007 // At this point we have proven something like this setup:
1008 // A = Allocate(...)
1009 // L = LoadQ(, AddP(CastPP(, A.Parm),, #Off))
1010 // S = StoreQ(, AddP(, A.Parm , #Off), V)
1011 // (Actually, we haven't yet proven the Q's are the same.)
1012 // In other words, we are loading from a casted version of
1013 // the same pointer-and-offset that we stored to.
1014 // Thus, we are able to replace L by V.
1015 }
1016 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
1017 if (store_Opcode() != st->Opcode())
1018 return NULL;
1019 return st->in(MemNode::ValueIn);
1020 }
1021
1022 // A load from a freshly-created object always returns zero.
1023 // (This can happen after LoadNode::Ideal resets the load's memory input
1024 // to find_captured_store, which returned InitializeNode::zero_memory.)
1025 if (st->is_Proj() && st->in(0)->is_Allocate() &&
1026 (st->in(0) == ld_alloc) &&
1027 (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) {
1028 // return a zero value for the load's basic type
1029 // (This is one of the few places where a generic PhaseTransform
1030 // can create new nodes. Think of it as lazily manifesting
1031 // virtually pre-existing constants.)
1032 return phase->zerocon(memory_type());
1033 }
1034
1035 // A load from an initialization barrier can match a captured store.
1036 if (st->is_Proj() && st->in(0)->is_Initialize()) {
1037 InitializeNode* init = st->in(0)->as_Initialize();
1038 AllocateNode* alloc = init->allocation();
1039 if ((alloc != NULL) && (alloc == ld_alloc)) {
1040 // examine a captured store value
1041 st = init->find_captured_store(ld_off, memory_size(), phase);
1042 if (st != NULL) {
1043 continue; // take one more trip around
1044 }
1045 }
1046 }
1047
1048 // Load boxed value from result of valueOf() call is input parameter.
1049 if (this->is_Load() && ld_adr->is_AddP() &&
1050 (tp != NULL) && tp->is_ptr_to_boxed_value()) {
1051 intptr_t ignore = 0;
1052 Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore);
1053 if (base != NULL && base->is_Proj() &&
1054 base->as_Proj()->_con == TypeFunc::Parms &&
1055 base->in(0)->is_CallStaticJava() &&
1056 base->in(0)->as_CallStaticJava()->is_boxing_method()) {
1057 return base->in(0)->in(TypeFunc::Parms);
1058 }
1059 }
1060
1061 break;
1062 }
1063
1064 return NULL;
1065 }
1066
1067 //----------------------is_instance_field_load_with_local_phi------------------
1068 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
1069 if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl &&
1070 in(Address)->is_AddP() ) {
1071 const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr();
1072 // Only instances and boxed values.
1073 if( t_oop != NULL &&
1074 (t_oop->is_ptr_to_boxed_value() ||
1075 t_oop->is_known_instance_field()) &&
1076 t_oop->offset() != Type::OffsetBot &&
1077 t_oop->offset() != Type::OffsetTop) {
1078 return true;
1079 }
1080 }
1081 return false;
1082 }
1083
1084 //------------------------------Identity---------------------------------------
1085 // Loads are identity if previous store is to same address
1086 Node *LoadNode::Identity( PhaseTransform *phase ) {
1087 // If the previous store-maker is the right kind of Store, and the store is
1088 // to the same address, then we are equal to the value stored.
1089 Node* mem = in(Memory);
1090 Node* value = can_see_stored_value(mem, phase);
1091 if( value ) {
1092 // byte, short & char stores truncate naturally.
1093 // A load has to load the truncated value which requires
1094 // some sort of masking operation and that requires an
1095 // Ideal call instead of an Identity call.
1096 if (memory_size() < BytesPerInt) {
1097 // If the input to the store does not fit with the load's result type,
1098 // it must be truncated via an Ideal call.
1099 if (!phase->type(value)->higher_equal(phase->type(this)))
1100 return this;
1101 }
1102 // (This works even when value is a Con, but LoadNode::Value
1103 // usually runs first, producing the singleton type of the Con.)
1104 return value;
1105 }
1106
1107 // Search for an existing data phi which was generated before for the same
1108 // instance's field to avoid infinite generation of phis in a loop.
1109 Node *region = mem->in(0);
1110 if (is_instance_field_load_with_local_phi(region)) {
1111 const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr();
1112 int this_index = phase->C->get_alias_index(addr_t);
1113 int this_offset = addr_t->offset();
1114 int this_iid = addr_t->instance_id();
1115 if (!addr_t->is_known_instance() &&
1116 addr_t->is_ptr_to_boxed_value()) {
1117 // Use _idx of address base (could be Phi node) for boxed values.
1118 intptr_t ignore = 0;
1119 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1120 this_iid = base->_idx;
1121 }
1122 const Type* this_type = bottom_type();
1123 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1124 Node* phi = region->fast_out(i);
1125 if (phi->is_Phi() && phi != mem &&
1126 phi->as_Phi()->is_same_inst_field(this_type, this_iid, this_index, this_offset)) {
1127 return phi;
1128 }
1129 }
1130 }
1131
1132 return this;
1133 }
1134
1135 // We're loading from an object which has autobox behaviour.
1136 // If this object is result of a valueOf call we'll have a phi
1137 // merging a newly allocated object and a load from the cache.
1138 // We want to replace this load with the original incoming
1139 // argument to the valueOf call.
1140 Node* LoadNode::eliminate_autobox(PhaseGVN* phase) {
1141 assert(phase->C->eliminate_boxing(), "sanity");
1142 intptr_t ignore = 0;
1143 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1144 if ((base == NULL) || base->is_Phi()) {
1145 // Push the loads from the phi that comes from valueOf up
1146 // through it to allow elimination of the loads and the recovery
1147 // of the original value. It is done in split_through_phi().
1148 return NULL;
1149 } else if (base->is_Load() ||
1150 base->is_DecodeN() && base->in(1)->is_Load()) {
1151 // Eliminate the load of boxed value for integer types from the cache
1152 // array by deriving the value from the index into the array.
1153 // Capture the offset of the load and then reverse the computation.
1154
1155 // Get LoadN node which loads a boxing object from 'cache' array.
1156 if (base->is_DecodeN()) {
1157 base = base->in(1);
1158 }
1159 if (!base->in(Address)->is_AddP()) {
1160 return NULL; // Complex address
1161 }
1162 AddPNode* address = base->in(Address)->as_AddP();
1163 Node* cache_base = address->in(AddPNode::Base);
1164 if ((cache_base != NULL) && cache_base->is_DecodeN()) {
1165 // Get ConP node which is static 'cache' field.
1166 cache_base = cache_base->in(1);
1167 }
1168 if ((cache_base != NULL) && cache_base->is_Con()) {
1169 const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr();
1170 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1171 Node* elements[4];
1172 int shift = exact_log2(type2aelembytes(T_OBJECT));
1173 int count = address->unpack_offsets(elements, ARRAY_SIZE(elements));
1174 if ((count > 0) && elements[0]->is_Con() &&
1175 ((count == 1) ||
1176 (count == 2) && elements[1]->Opcode() == Op_LShiftX &&
1177 elements[1]->in(2) == phase->intcon(shift))) {
1178 ciObjArray* array = base_type->const_oop()->as_obj_array();
1179 // Fetch the box object cache[0] at the base of the array and get its value
1180 ciInstance* box = array->obj_at(0)->as_instance();
1181 ciInstanceKlass* ik = box->klass()->as_instance_klass();
1182 assert(ik->is_box_klass(), "sanity");
1183 assert(ik->nof_nonstatic_fields() == 1, "change following code");
1184 if (ik->nof_nonstatic_fields() == 1) {
1185 // This should be true nonstatic_field_at requires calling
1186 // nof_nonstatic_fields so check it anyway
1187 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1188 BasicType bt = c.basic_type();
1189 // Only integer types have boxing cache.
1190 assert(bt == T_BOOLEAN || bt == T_CHAR ||
1191 bt == T_BYTE || bt == T_SHORT ||
1192 bt == T_INT || bt == T_LONG, err_msg_res("wrong type = %s", type2name(bt)));
1193 jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int();
1194 if (cache_low != (int)cache_low) {
1195 return NULL; // should not happen since cache is array indexed by value
1196 }
1197 jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift);
1198 if (offset != (int)offset) {
1199 return NULL; // should not happen since cache is array indexed by value
1200 }
1201 // Add up all the offsets making of the address of the load
1202 Node* result = elements[0];
1203 for (int i = 1; i < count; i++) {
1204 result = phase->transform(new AddXNode(result, elements[i]));
1205 }
1206 // Remove the constant offset from the address and then
1207 result = phase->transform(new AddXNode(result, phase->MakeConX(-(int)offset)));
1208 // remove the scaling of the offset to recover the original index.
1209 if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) {
1210 // Peel the shift off directly but wrap it in a dummy node
1211 // since Ideal can't return existing nodes
1212 result = new RShiftXNode(result->in(1), phase->intcon(0));
1213 } else if (result->is_Add() && result->in(2)->is_Con() &&
1214 result->in(1)->Opcode() == Op_LShiftX &&
1215 result->in(1)->in(2) == phase->intcon(shift)) {
1216 // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z)
1217 // but for boxing cache access we know that X<<Z will not overflow
1218 // (there is range check) so we do this optimizatrion by hand here.
1219 Node* add_con = new RShiftXNode(result->in(2), phase->intcon(shift));
1220 result = new AddXNode(result->in(1)->in(1), phase->transform(add_con));
1221 } else {
1222 result = new RShiftXNode(result, phase->intcon(shift));
1223 }
1224 #ifdef _LP64
1225 if (bt != T_LONG) {
1226 result = new ConvL2INode(phase->transform(result));
1227 }
1228 #else
1229 if (bt == T_LONG) {
1230 result = new ConvI2LNode(phase->transform(result));
1231 }
1232 #endif
1233 // Boxing/unboxing can be done from signed & unsigned loads (e.g. LoadUB -> ... -> LoadB pair).
1234 // Need to preserve unboxing load type if it is unsigned.
1235 switch(this->Opcode()) {
1236 case Op_LoadUB:
1237 result = new AndINode(phase->transform(result), phase->intcon(0xFF));
1238 break;
1239 case Op_LoadUS:
1240 result = new AndINode(phase->transform(result), phase->intcon(0xFFFF));
1241 break;
1242 }
1243 return result;
1244 }
1245 }
1246 }
1247 }
1248 }
1249 return NULL;
1250 }
1251
1252 static bool stable_phi(PhiNode* phi, PhaseGVN *phase) {
1253 Node* region = phi->in(0);
1254 if (region == NULL) {
1255 return false; // Wait stable graph
1256 }
1257 uint cnt = phi->req();
1258 for (uint i = 1; i < cnt; i++) {
1259 Node* rc = region->in(i);
1260 if (rc == NULL || phase->type(rc) == Type::TOP)
1261 return false; // Wait stable graph
1262 Node* in = phi->in(i);
1263 if (in == NULL || phase->type(in) == Type::TOP)
1264 return false; // Wait stable graph
1265 }
1266 return true;
1267 }
1268 //------------------------------split_through_phi------------------------------
1269 // Split instance or boxed field load through Phi.
1270 Node *LoadNode::split_through_phi(PhaseGVN *phase) {
1271 Node* mem = in(Memory);
1272 Node* address = in(Address);
1273 const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr();
1274
1275 assert((t_oop != NULL) &&
1276 (t_oop->is_known_instance_field() ||
1277 t_oop->is_ptr_to_boxed_value()), "invalide conditions");
1278
1279 Compile* C = phase->C;
1280 intptr_t ignore = 0;
1281 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1282 bool base_is_phi = (base != NULL) && base->is_Phi();
1283 bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() &&
1284 (base != NULL) && (base == address->in(AddPNode::Base)) &&
1285 phase->type(base)->higher_equal(TypePtr::NOTNULL);
1286
1287 if (!((mem->is_Phi() || base_is_phi) &&
1288 (load_boxed_values || t_oop->is_known_instance_field()))) {
1289 return NULL; // memory is not Phi
1290 }
1291
1292 if (mem->is_Phi()) {
1293 if (!stable_phi(mem->as_Phi(), phase)) {
1294 return NULL; // Wait stable graph
1295 }
1296 uint cnt = mem->req();
1297 // Check for loop invariant memory.
1298 if (cnt == 3) {
1299 for (uint i = 1; i < cnt; i++) {
1300 Node* in = mem->in(i);
1301 Node* m = optimize_memory_chain(in, t_oop, this, phase);
1302 if (m == mem) {
1303 set_req(Memory, mem->in(cnt - i));
1304 return this; // made change
1305 }
1306 }
1307 }
1308 }
1309 if (base_is_phi) {
1310 if (!stable_phi(base->as_Phi(), phase)) {
1311 return NULL; // Wait stable graph
1312 }
1313 uint cnt = base->req();
1314 // Check for loop invariant memory.
1315 if (cnt == 3) {
1316 for (uint i = 1; i < cnt; i++) {
1317 if (base->in(i) == base) {
1318 return NULL; // Wait stable graph
1319 }
1320 }
1321 }
1322 }
1323
1324 bool load_boxed_phi = load_boxed_values && base_is_phi && (base->in(0) == mem->in(0));
1325
1326 // Split through Phi (see original code in loopopts.cpp).
1327 assert(C->have_alias_type(t_oop), "instance should have alias type");
1328
1329 // Do nothing here if Identity will find a value
1330 // (to avoid infinite chain of value phis generation).
1331 if (!phase->eqv(this, this->Identity(phase)))
1332 return NULL;
1333
1334 // Select Region to split through.
1335 Node* region;
1336 if (!base_is_phi) {
1337 assert(mem->is_Phi(), "sanity");
1338 region = mem->in(0);
1339 // Skip if the region dominates some control edge of the address.
1340 if (!MemNode::all_controls_dominate(address, region))
1341 return NULL;
1342 } else if (!mem->is_Phi()) {
1343 assert(base_is_phi, "sanity");
1344 region = base->in(0);
1345 // Skip if the region dominates some control edge of the memory.
1346 if (!MemNode::all_controls_dominate(mem, region))
1347 return NULL;
1348 } else if (base->in(0) != mem->in(0)) {
1349 assert(base_is_phi && mem->is_Phi(), "sanity");
1350 if (MemNode::all_controls_dominate(mem, base->in(0))) {
1351 region = base->in(0);
1352 } else if (MemNode::all_controls_dominate(address, mem->in(0))) {
1353 region = mem->in(0);
1354 } else {
1355 return NULL; // complex graph
1356 }
1357 } else {
1358 assert(base->in(0) == mem->in(0), "sanity");
1359 region = mem->in(0);
1360 }
1361
1362 const Type* this_type = this->bottom_type();
1363 int this_index = C->get_alias_index(t_oop);
1364 int this_offset = t_oop->offset();
1365 int this_iid = t_oop->instance_id();
1366 if (!t_oop->is_known_instance() && load_boxed_values) {
1367 // Use _idx of address base for boxed values.
1368 this_iid = base->_idx;
1369 }
1370 PhaseIterGVN* igvn = phase->is_IterGVN();
1371 Node* phi = new PhiNode(region, this_type, NULL, this_iid, this_index, this_offset);
1372 for (uint i = 1; i < region->req(); i++) {
1373 Node* x;
1374 Node* the_clone = NULL;
1375 if (region->in(i) == C->top()) {
1376 x = C->top(); // Dead path? Use a dead data op
1377 } else {
1378 x = this->clone(); // Else clone up the data op
1379 the_clone = x; // Remember for possible deletion.
1380 // Alter data node to use pre-phi inputs
1381 if (this->in(0) == region) {
1382 x->set_req(0, region->in(i));
1383 } else {
1384 x->set_req(0, NULL);
1385 }
1386 if (mem->is_Phi() && (mem->in(0) == region)) {
1387 x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone.
1388 }
1389 if (address->is_Phi() && address->in(0) == region) {
1390 x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone
1391 }
1392 if (base_is_phi && (base->in(0) == region)) {
1393 Node* base_x = base->in(i); // Clone address for loads from boxed objects.
1394 Node* adr_x = phase->transform(new AddPNode(base_x,base_x,address->in(AddPNode::Offset)));
1395 x->set_req(Address, adr_x);
1396 }
1397 }
1398 // Check for a 'win' on some paths
1399 const Type *t = x->Value(igvn);
1400
1401 bool singleton = t->singleton();
1402
1403 // See comments in PhaseIdealLoop::split_thru_phi().
1404 if (singleton && t == Type::TOP) {
1405 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1406 }
1407
1408 if (singleton) {
1409 x = igvn->makecon(t);
1410 } else {
1411 // We now call Identity to try to simplify the cloned node.
1412 // Note that some Identity methods call phase->type(this).
1413 // Make sure that the type array is big enough for
1414 // our new node, even though we may throw the node away.
1415 // (This tweaking with igvn only works because x is a new node.)
1416 igvn->set_type(x, t);
1417 // If x is a TypeNode, capture any more-precise type permanently into Node
1418 // otherwise it will be not updated during igvn->transform since
1419 // igvn->type(x) is set to x->Value() already.
1420 x->raise_bottom_type(t);
1421 Node *y = x->Identity(igvn);
1422 if (y != x) {
1423 x = y;
1424 } else {
1425 y = igvn->hash_find_insert(x);
1426 if (y) {
1427 x = y;
1428 } else {
1429 // Else x is a new node we are keeping
1430 // We do not need register_new_node_with_optimizer
1431 // because set_type has already been called.
1432 igvn->_worklist.push(x);
1433 }
1434 }
1435 }
1436 if (x != the_clone && the_clone != NULL) {
1437 igvn->remove_dead_node(the_clone);
1438 }
1439 phi->set_req(i, x);
1440 }
1441 // Record Phi
1442 igvn->register_new_node_with_optimizer(phi);
1443 return phi;
1444 }
1445
1446 //------------------------------Ideal------------------------------------------
1447 // If the load is from Field memory and the pointer is non-null, it might be possible to
1448 // zero out the control input.
1449 // If the offset is constant and the base is an object allocation,
1450 // try to hook me up to the exact initializing store.
1451 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1452 Node* p = MemNode::Ideal_common(phase, can_reshape);
1453 if (p) return (p == NodeSentinel) ? NULL : p;
1454
1455 Node* ctrl = in(MemNode::Control);
1456 Node* address = in(MemNode::Address);
1457 bool progress = false;
1458
1459 // Skip up past a SafePoint control. Cannot do this for Stores because
1460 // pointer stores & cardmarks must stay on the same side of a SafePoint.
1461 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint &&
1462 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw ) {
1463 ctrl = ctrl->in(0);
1464 set_req(MemNode::Control,ctrl);
1465 progress = true;
1466 }
1467
1468 intptr_t ignore = 0;
1469 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1470 if (base != NULL
1471 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
1472 // Check for useless control edge in some common special cases
1473 if (in(MemNode::Control) != NULL
1474 && can_remove_control()
1475 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1476 && all_controls_dominate(base, phase->C->start())) {
1477 // A method-invariant, non-null address (constant or 'this' argument).
1478 set_req(MemNode::Control, NULL);
1479 progress = true;
1480 }
1481 }
1482
1483 Node* mem = in(MemNode::Memory);
1484 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1485
1486 if (can_reshape && (addr_t != NULL)) {
1487 // try to optimize our memory input
1488 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase);
1489 if (opt_mem != mem) {
1490 set_req(MemNode::Memory, opt_mem);
1491 if (phase->type( opt_mem ) == Type::TOP) return NULL;
1492 return this;
1493 }
1494 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1495 if ((t_oop != NULL) &&
1496 (t_oop->is_known_instance_field() ||
1497 t_oop->is_ptr_to_boxed_value())) {
1498 PhaseIterGVN *igvn = phase->is_IterGVN();
1499 if (igvn != NULL && igvn->_worklist.member(opt_mem)) {
1500 // Delay this transformation until memory Phi is processed.
1501 phase->is_IterGVN()->_worklist.push(this);
1502 return NULL;
1503 }
1504 // Split instance field load through Phi.
1505 Node* result = split_through_phi(phase);
1506 if (result != NULL) return result;
1507
1508 if (t_oop->is_ptr_to_boxed_value()) {
1509 Node* result = eliminate_autobox(phase);
1510 if (result != NULL) return result;
1511 }
1512 }
1513 }
1514
1515 // Is there a dominating load that loads the same value? Leave
1516 // anything that is not a load of a field/array element (like
1517 // barriers etc.) alone
1518 if (in(0) != NULL && adr_type() != TypeRawPtr::BOTTOM && can_reshape) {
1519 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) {
1520 Node *use = mem->fast_out(i);
1521 if (use != this &&
1522 use->Opcode() == Opcode() &&
1523 use->in(0) != NULL &&
1524 use->in(0) != in(0) &&
1525 use->in(Address) == in(Address)) {
1526 Node* ctl = in(0);
1527 for (int i = 0; i < 10 && ctl != NULL; i++) {
1528 ctl = IfNode::up_one_dom(ctl);
1529 if (ctl == use->in(0)) {
1530 set_req(0, use->in(0));
1531 return this;
1532 }
1533 }
1534 }
1535 }
1536 }
1537
1538 // Check for prior store with a different base or offset; make Load
1539 // independent. Skip through any number of them. Bail out if the stores
1540 // are in an endless dead cycle and report no progress. This is a key
1541 // transform for Reflection. However, if after skipping through the Stores
1542 // we can't then fold up against a prior store do NOT do the transform as
1543 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
1544 // array memory alive twice: once for the hoisted Load and again after the
1545 // bypassed Store. This situation only works if EVERYBODY who does
1546 // anti-dependence work knows how to bypass. I.e. we need all
1547 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
1548 // the alias index stuff. So instead, peek through Stores and IFF we can
1549 // fold up, do so.
1550 Node* prev_mem = find_previous_store(phase);
1551 if (prev_mem != NULL) {
1552 Node* value = can_see_arraycopy_value(prev_mem, phase);
1553 if (value != NULL) {
1554 return value;
1555 }
1556 }
1557 // Steps (a), (b): Walk past independent stores to find an exact match.
1558 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) {
1559 // (c) See if we can fold up on the spot, but don't fold up here.
1560 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
1561 // just return a prior value, which is done by Identity calls.
1562 if (can_see_stored_value(prev_mem, phase)) {
1563 // Make ready for step (d):
1564 set_req(MemNode::Memory, prev_mem);
1565 return this;
1566 }
1567 }
1568
1569 return progress ? this : NULL;
1570 }
1571
1572 // Helper to recognize certain Klass fields which are invariant across
1573 // some group of array types (e.g., int[] or all T[] where T < Object).
1574 const Type*
1575 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1576 ciKlass* klass) const {
1577 if (tkls->offset() == in_bytes(Klass::modifier_flags_offset())) {
1578 // The field is Klass::_modifier_flags. Return its (constant) value.
1579 // (Folds up the 2nd indirection in aClassConstant.getModifiers().)
1580 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags");
1581 return TypeInt::make(klass->modifier_flags());
1582 }
1583 if (tkls->offset() == in_bytes(Klass::access_flags_offset())) {
1584 // The field is Klass::_access_flags. Return its (constant) value.
1585 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1586 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags");
1587 return TypeInt::make(klass->access_flags());
1588 }
1589 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) {
1590 // The field is Klass::_layout_helper. Return its constant value if known.
1591 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper");
1592 return TypeInt::make(klass->layout_helper());
1593 }
1594
1595 // No match.
1596 return NULL;
1597 }
1598
1599 // Try to constant-fold a stable array element.
1600 static const Type* fold_stable_ary_elem(const TypeAryPtr* ary, int off, BasicType loadbt) {
1601 assert(ary->const_oop(), "array should be constant");
1602 assert(ary->is_stable(), "array should be stable");
1603
1604 // Decode the results of GraphKit::array_element_address.
1605 ciArray* aobj = ary->const_oop()->as_array();
1606 ciConstant con = aobj->element_value_by_offset(off);
1607
1608 if (con.basic_type() != T_ILLEGAL && !con.is_null_or_zero()) {
1609 const Type* con_type = Type::make_from_constant(con);
1610 if (con_type != NULL) {
1611 if (con_type->isa_aryptr()) {
1612 // Join with the array element type, in case it is also stable.
1613 int dim = ary->stable_dimension();
1614 con_type = con_type->is_aryptr()->cast_to_stable(true, dim-1);
1615 }
1616 if (loadbt == T_NARROWOOP && con_type->isa_oopptr()) {
1617 con_type = con_type->make_narrowoop();
1618 }
1619 #ifndef PRODUCT
1620 if (TraceIterativeGVN) {
1621 tty->print("FoldStableValues: array element [off=%d]: con_type=", off);
1622 con_type->dump(); tty->cr();
1623 }
1624 #endif //PRODUCT
1625 return con_type;
1626 }
1627 }
1628 return NULL;
1629 }
1630
1631 //------------------------------Value-----------------------------------------
1632 const Type *LoadNode::Value( PhaseTransform *phase ) const {
1633 // Either input is TOP ==> the result is TOP
1634 Node* mem = in(MemNode::Memory);
1635 const Type *t1 = phase->type(mem);
1636 if (t1 == Type::TOP) return Type::TOP;
1637 Node* adr = in(MemNode::Address);
1638 const TypePtr* tp = phase->type(adr)->isa_ptr();
1639 if (tp == NULL || tp->empty()) return Type::TOP;
1640 int off = tp->offset();
1641 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
1642 Compile* C = phase->C;
1643
1644 // Try to guess loaded type from pointer type
1645 if (tp->isa_aryptr()) {
1646 const TypeAryPtr* ary = tp->is_aryptr();
1647 const Type* t = ary->elem();
1648
1649 // Determine whether the reference is beyond the header or not, by comparing
1650 // the offset against the offset of the start of the array's data.
1651 // Different array types begin at slightly different offsets (12 vs. 16).
1652 // We choose T_BYTE as an example base type that is least restrictive
1653 // as to alignment, which will therefore produce the smallest
1654 // possible base offset.
1655 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
1656 const bool off_beyond_header = ((uint)off >= (uint)min_base_off);
1657
1658 // Try to constant-fold a stable array element.
1659 if (FoldStableValues && ary->is_stable() && ary->const_oop() != NULL) {
1660 // Make sure the reference is not into the header and the offset is constant
1661 if (off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) {
1662 const Type* con_type = fold_stable_ary_elem(ary, off, memory_type());
1663 if (con_type != NULL) {
1664 return con_type;
1665 }
1666 }
1667 }
1668
1669 // Don't do this for integer types. There is only potential profit if
1670 // the element type t is lower than _type; that is, for int types, if _type is
1671 // more restrictive than t. This only happens here if one is short and the other
1672 // char (both 16 bits), and in those cases we've made an intentional decision
1673 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
1674 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
1675 //
1676 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
1677 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
1678 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
1679 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
1680 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
1681 // In fact, that could have been the original type of p1, and p1 could have
1682 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
1683 // expression (LShiftL quux 3) independently optimized to the constant 8.
1684 if ((t->isa_int() == NULL) && (t->isa_long() == NULL)
1685 && (_type->isa_vect() == NULL)
1686 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
1687 // t might actually be lower than _type, if _type is a unique
1688 // concrete subclass of abstract class t.
1689 if (off_beyond_header) { // is the offset beyond the header?
1690 const Type* jt = t->join_speculative(_type);
1691 // In any case, do not allow the join, per se, to empty out the type.
1692 if (jt->empty() && !t->empty()) {
1693 // This can happen if a interface-typed array narrows to a class type.
1694 jt = _type;
1695 }
1696 #ifdef ASSERT
1697 if (phase->C->eliminate_boxing() && adr->is_AddP()) {
1698 // The pointers in the autobox arrays are always non-null
1699 Node* base = adr->in(AddPNode::Base);
1700 if ((base != NULL) && base->is_DecodeN()) {
1701 // Get LoadN node which loads IntegerCache.cache field
1702 base = base->in(1);
1703 }
1704 if ((base != NULL) && base->is_Con()) {
1705 const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr();
1706 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1707 // It could be narrow oop
1708 assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity");
1709 }
1710 }
1711 }
1712 #endif
1713 return jt;
1714 }
1715 }
1716 } else if (tp->base() == Type::InstPtr) {
1717 ciEnv* env = C->env();
1718 const TypeInstPtr* tinst = tp->is_instptr();
1719 ciKlass* klass = tinst->klass();
1720 assert( off != Type::OffsetBot ||
1721 // arrays can be cast to Objects
1722 tp->is_oopptr()->klass()->is_java_lang_Object() ||
1723 // unsafe field access may not have a constant offset
1724 C->has_unsafe_access(),
1725 "Field accesses must be precise" );
1726 // For oop loads, we expect the _type to be precise
1727 if (klass == env->String_klass() &&
1728 adr->is_AddP() && off != Type::OffsetBot) {
1729 // For constant Strings treat the final fields as compile time constants.
1730 Node* base = adr->in(AddPNode::Base);
1731 const TypeOopPtr* t = phase->type(base)->isa_oopptr();
1732 if (t != NULL && t->singleton()) {
1733 ciField* field = env->String_klass()->get_field_by_offset(off, false);
1734 if (field != NULL && field->is_final()) {
1735 ciObject* string = t->const_oop();
1736 ciConstant constant = string->as_instance()->field_value(field);
1737 if (constant.basic_type() == T_INT) {
1738 return TypeInt::make(constant.as_int());
1739 } else if (constant.basic_type() == T_ARRAY) {
1740 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
1741 return TypeNarrowOop::make_from_constant(constant.as_object(), true);
1742 } else {
1743 return TypeOopPtr::make_from_constant(constant.as_object(), true);
1744 }
1745 }
1746 }
1747 }
1748 }
1749 // Optimizations for constant objects
1750 ciObject* const_oop = tinst->const_oop();
1751 if (const_oop != NULL) {
1752 // For constant Boxed value treat the target field as a compile time constant.
1753 if (tinst->is_ptr_to_boxed_value()) {
1754 return tinst->get_const_boxed_value();
1755 } else
1756 // For constant CallSites treat the target field as a compile time constant.
1757 if (const_oop->is_call_site()) {
1758 ciCallSite* call_site = const_oop->as_call_site();
1759 ciField* field = call_site->klass()->as_instance_klass()->get_field_by_offset(off, /*is_static=*/ false);
1760 if (field != NULL && field->is_call_site_target()) {
1761 ciMethodHandle* target = call_site->get_target();
1762 if (target != NULL) { // just in case
1763 ciConstant constant(T_OBJECT, target);
1764 const Type* t;
1765 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
1766 t = TypeNarrowOop::make_from_constant(constant.as_object(), true);
1767 } else {
1768 t = TypeOopPtr::make_from_constant(constant.as_object(), true);
1769 }
1770 // Add a dependence for invalidation of the optimization.
1771 if (!call_site->is_constant_call_site()) {
1772 C->dependencies()->assert_call_site_target_value(call_site, target);
1773 }
1774 return t;
1775 }
1776 }
1777 }
1778 }
1779 } else if (tp->base() == Type::KlassPtr) {
1780 assert( off != Type::OffsetBot ||
1781 // arrays can be cast to Objects
1782 tp->is_klassptr()->klass()->is_java_lang_Object() ||
1783 // also allow array-loading from the primary supertype
1784 // array during subtype checks
1785 Opcode() == Op_LoadKlass,
1786 "Field accesses must be precise" );
1787 // For klass/static loads, we expect the _type to be precise
1788 }
1789
1790 const TypeKlassPtr *tkls = tp->isa_klassptr();
1791 if (tkls != NULL && !StressReflectiveCode) {
1792 ciKlass* klass = tkls->klass();
1793 if (klass->is_loaded() && tkls->klass_is_exact()) {
1794 // We are loading a field from a Klass metaobject whose identity
1795 // is known at compile time (the type is "exact" or "precise").
1796 // Check for fields we know are maintained as constants by the VM.
1797 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) {
1798 // The field is Klass::_super_check_offset. Return its (constant) value.
1799 // (Folds up type checking code.)
1800 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
1801 return TypeInt::make(klass->super_check_offset());
1802 }
1803 // Compute index into primary_supers array
1804 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1805 // Check for overflowing; use unsigned compare to handle the negative case.
1806 if( depth < ciKlass::primary_super_limit() ) {
1807 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1808 // (Folds up type checking code.)
1809 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1810 ciKlass *ss = klass->super_of_depth(depth);
1811 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1812 }
1813 const Type* aift = load_array_final_field(tkls, klass);
1814 if (aift != NULL) return aift;
1815 if (tkls->offset() == in_bytes(Klass::java_mirror_offset())) {
1816 // The field is Klass::_java_mirror. Return its (constant) value.
1817 // (Folds up the 2nd indirection in anObjConstant.getClass().)
1818 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
1819 return TypeInstPtr::make(klass->java_mirror());
1820 }
1821 }
1822
1823 // We can still check if we are loading from the primary_supers array at a
1824 // shallow enough depth. Even though the klass is not exact, entries less
1825 // than or equal to its super depth are correct.
1826 if (klass->is_loaded() ) {
1827 ciType *inner = klass;
1828 while( inner->is_obj_array_klass() )
1829 inner = inner->as_obj_array_klass()->base_element_type();
1830 if( inner->is_instance_klass() &&
1831 !inner->as_instance_klass()->flags().is_interface() ) {
1832 // Compute index into primary_supers array
1833 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1834 // Check for overflowing; use unsigned compare to handle the negative case.
1835 if( depth < ciKlass::primary_super_limit() &&
1836 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case
1837 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1838 // (Folds up type checking code.)
1839 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1840 ciKlass *ss = klass->super_of_depth(depth);
1841 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1842 }
1843 }
1844 }
1845
1846 // If the type is enough to determine that the thing is not an array,
1847 // we can give the layout_helper a positive interval type.
1848 // This will help short-circuit some reflective code.
1849 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())
1850 && !klass->is_array_klass() // not directly typed as an array
1851 && !klass->is_interface() // specifically not Serializable & Cloneable
1852 && !klass->is_java_lang_Object() // not the supertype of all T[]
1853 ) {
1854 // Note: When interfaces are reliable, we can narrow the interface
1855 // test to (klass != Serializable && klass != Cloneable).
1856 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
1857 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
1858 // The key property of this type is that it folds up tests
1859 // for array-ness, since it proves that the layout_helper is positive.
1860 // Thus, a generic value like the basic object layout helper works fine.
1861 return TypeInt::make(min_size, max_jint, Type::WidenMin);
1862 }
1863 }
1864
1865 // If we are loading from a freshly-allocated object, produce a zero,
1866 // if the load is provably beyond the header of the object.
1867 // (Also allow a variable load from a fresh array to produce zero.)
1868 const TypeOopPtr *tinst = tp->isa_oopptr();
1869 bool is_instance = (tinst != NULL) && tinst->is_known_instance_field();
1870 bool is_boxed_value = (tinst != NULL) && tinst->is_ptr_to_boxed_value();
1871 if (ReduceFieldZeroing || is_instance || is_boxed_value) {
1872 Node* value = can_see_stored_value(mem,phase);
1873 if (value != NULL && value->is_Con()) {
1874 assert(value->bottom_type()->higher_equal(_type),"sanity");
1875 return value->bottom_type();
1876 }
1877 }
1878
1879 if (is_instance) {
1880 // If we have an instance type and our memory input is the
1881 // programs's initial memory state, there is no matching store,
1882 // so just return a zero of the appropriate type
1883 Node *mem = in(MemNode::Memory);
1884 if (mem->is_Parm() && mem->in(0)->is_Start()) {
1885 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
1886 return Type::get_zero_type(_type->basic_type());
1887 }
1888 }
1889 return _type;
1890 }
1891
1892 //------------------------------match_edge-------------------------------------
1893 // Do we Match on this edge index or not? Match only the address.
1894 uint LoadNode::match_edge(uint idx) const {
1895 return idx == MemNode::Address;
1896 }
1897
1898 //--------------------------LoadBNode::Ideal--------------------------------------
1899 //
1900 // If the previous store is to the same address as this load,
1901 // and the value stored was larger than a byte, replace this load
1902 // with the value stored truncated to a byte. If no truncation is
1903 // needed, the replacement is done in LoadNode::Identity().
1904 //
1905 Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1906 Node* mem = in(MemNode::Memory);
1907 Node* value = can_see_stored_value(mem,phase);
1908 if( value && !phase->type(value)->higher_equal( _type ) ) {
1909 Node *result = phase->transform( new LShiftINode(value, phase->intcon(24)) );
1910 return new RShiftINode(result, phase->intcon(24));
1911 }
1912 // Identity call will handle the case where truncation is not needed.
1913 return LoadNode::Ideal(phase, can_reshape);
1914 }
1915
1916 const Type* LoadBNode::Value(PhaseTransform *phase) const {
1917 Node* mem = in(MemNode::Memory);
1918 Node* value = can_see_stored_value(mem,phase);
1919 if (value != NULL && value->is_Con() &&
1920 !value->bottom_type()->higher_equal(_type)) {
1921 // If the input to the store does not fit with the load's result type,
1922 // it must be truncated. We can't delay until Ideal call since
1923 // a singleton Value is needed for split_thru_phi optimization.
1924 int con = value->get_int();
1925 return TypeInt::make((con << 24) >> 24);
1926 }
1927 return LoadNode::Value(phase);
1928 }
1929
1930 //--------------------------LoadUBNode::Ideal-------------------------------------
1931 //
1932 // If the previous store is to the same address as this load,
1933 // and the value stored was larger than a byte, replace this load
1934 // with the value stored truncated to a byte. If no truncation is
1935 // needed, the replacement is done in LoadNode::Identity().
1936 //
1937 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
1938 Node* mem = in(MemNode::Memory);
1939 Node* value = can_see_stored_value(mem, phase);
1940 if (value && !phase->type(value)->higher_equal(_type))
1941 return new AndINode(value, phase->intcon(0xFF));
1942 // Identity call will handle the case where truncation is not needed.
1943 return LoadNode::Ideal(phase, can_reshape);
1944 }
1945
1946 const Type* LoadUBNode::Value(PhaseTransform *phase) const {
1947 Node* mem = in(MemNode::Memory);
1948 Node* value = can_see_stored_value(mem,phase);
1949 if (value != NULL && value->is_Con() &&
1950 !value->bottom_type()->higher_equal(_type)) {
1951 // If the input to the store does not fit with the load's result type,
1952 // it must be truncated. We can't delay until Ideal call since
1953 // a singleton Value is needed for split_thru_phi optimization.
1954 int con = value->get_int();
1955 return TypeInt::make(con & 0xFF);
1956 }
1957 return LoadNode::Value(phase);
1958 }
1959
1960 //--------------------------LoadUSNode::Ideal-------------------------------------
1961 //
1962 // If the previous store is to the same address as this load,
1963 // and the value stored was larger than a char, replace this load
1964 // with the value stored truncated to a char. If no truncation is
1965 // needed, the replacement is done in LoadNode::Identity().
1966 //
1967 Node *LoadUSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1968 Node* mem = in(MemNode::Memory);
1969 Node* value = can_see_stored_value(mem,phase);
1970 if( value && !phase->type(value)->higher_equal( _type ) )
1971 return new AndINode(value,phase->intcon(0xFFFF));
1972 // Identity call will handle the case where truncation is not needed.
1973 return LoadNode::Ideal(phase, can_reshape);
1974 }
1975
1976 const Type* LoadUSNode::Value(PhaseTransform *phase) const {
1977 Node* mem = in(MemNode::Memory);
1978 Node* value = can_see_stored_value(mem,phase);
1979 if (value != NULL && value->is_Con() &&
1980 !value->bottom_type()->higher_equal(_type)) {
1981 // If the input to the store does not fit with the load's result type,
1982 // it must be truncated. We can't delay until Ideal call since
1983 // a singleton Value is needed for split_thru_phi optimization.
1984 int con = value->get_int();
1985 return TypeInt::make(con & 0xFFFF);
1986 }
1987 return LoadNode::Value(phase);
1988 }
1989
1990 //--------------------------LoadSNode::Ideal--------------------------------------
1991 //
1992 // If the previous store is to the same address as this load,
1993 // and the value stored was larger than a short, replace this load
1994 // with the value stored truncated to a short. If no truncation is
1995 // needed, the replacement is done in LoadNode::Identity().
1996 //
1997 Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1998 Node* mem = in(MemNode::Memory);
1999 Node* value = can_see_stored_value(mem,phase);
2000 if( value && !phase->type(value)->higher_equal( _type ) ) {
2001 Node *result = phase->transform( new LShiftINode(value, phase->intcon(16)) );
2002 return new RShiftINode(result, phase->intcon(16));
2003 }
2004 // Identity call will handle the case where truncation is not needed.
2005 return LoadNode::Ideal(phase, can_reshape);
2006 }
2007
2008 const Type* LoadSNode::Value(PhaseTransform *phase) const {
2009 Node* mem = in(MemNode::Memory);
2010 Node* value = can_see_stored_value(mem,phase);
2011 if (value != NULL && value->is_Con() &&
2012 !value->bottom_type()->higher_equal(_type)) {
2013 // If the input to the store does not fit with the load's result type,
2014 // it must be truncated. We can't delay until Ideal call since
2015 // a singleton Value is needed for split_thru_phi optimization.
2016 int con = value->get_int();
2017 return TypeInt::make((con << 16) >> 16);
2018 }
2019 return LoadNode::Value(phase);
2020 }
2021
2022 //=============================================================================
2023 //----------------------------LoadKlassNode::make------------------------------
2024 // Polymorphic factory method:
2025 Node* LoadKlassNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* at, const TypeKlassPtr* tk) {
2026 // sanity check the alias category against the created node type
2027 const TypePtr *adr_type = adr->bottom_type()->isa_ptr();
2028 assert(adr_type != NULL, "expecting TypeKlassPtr");
2029 #ifdef _LP64
2030 if (adr_type->is_ptr_to_narrowklass()) {
2031 assert(UseCompressedClassPointers, "no compressed klasses");
2032 Node* load_klass = gvn.transform(new LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowklass(), MemNode::unordered));
2033 return new DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr());
2034 }
2035 #endif
2036 assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
2037 return new LoadKlassNode(ctl, mem, adr, at, tk, MemNode::unordered);
2038 }
2039
2040 //------------------------------Value------------------------------------------
2041 const Type *LoadKlassNode::Value( PhaseTransform *phase ) const {
2042 return klass_value_common(phase);
2043 }
2044
2045 // In most cases, LoadKlassNode does not have the control input set. If the control
2046 // input is set, it must not be removed (by LoadNode::Ideal()).
2047 bool LoadKlassNode::can_remove_control() const {
2048 return false;
2049 }
2050
2051 const Type *LoadNode::klass_value_common( PhaseTransform *phase ) const {
2052 // Either input is TOP ==> the result is TOP
2053 const Type *t1 = phase->type( in(MemNode::Memory) );
2054 if (t1 == Type::TOP) return Type::TOP;
2055 Node *adr = in(MemNode::Address);
2056 const Type *t2 = phase->type( adr );
2057 if (t2 == Type::TOP) return Type::TOP;
2058 const TypePtr *tp = t2->is_ptr();
2059 if (TypePtr::above_centerline(tp->ptr()) ||
2060 tp->ptr() == TypePtr::Null) return Type::TOP;
2061
2062 // Return a more precise klass, if possible
2063 const TypeInstPtr *tinst = tp->isa_instptr();
2064 if (tinst != NULL) {
2065 ciInstanceKlass* ik = tinst->klass()->as_instance_klass();
2066 int offset = tinst->offset();
2067 if (ik == phase->C->env()->Class_klass()
2068 && (offset == java_lang_Class::klass_offset_in_bytes() ||
2069 offset == java_lang_Class::array_klass_offset_in_bytes())) {
2070 // We are loading a special hidden field from a Class mirror object,
2071 // the field which points to the VM's Klass metaobject.
2072 ciType* t = tinst->java_mirror_type();
2073 // java_mirror_type returns non-null for compile-time Class constants.
2074 if (t != NULL) {
2075 // constant oop => constant klass
2076 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
2077 if (t->is_void()) {
2078 // We cannot create a void array. Since void is a primitive type return null
2079 // klass. Users of this result need to do a null check on the returned klass.
2080 return TypePtr::NULL_PTR;
2081 }
2082 return TypeKlassPtr::make(ciArrayKlass::make(t));
2083 }
2084 if (!t->is_klass()) {
2085 // a primitive Class (e.g., int.class) has NULL for a klass field
2086 return TypePtr::NULL_PTR;
2087 }
2088 // (Folds up the 1st indirection in aClassConstant.getModifiers().)
2089 return TypeKlassPtr::make(t->as_klass());
2090 }
2091 // non-constant mirror, so we can't tell what's going on
2092 }
2093 if( !ik->is_loaded() )
2094 return _type; // Bail out if not loaded
2095 if (offset == oopDesc::klass_offset_in_bytes()) {
2096 if (tinst->klass_is_exact()) {
2097 return TypeKlassPtr::make(ik);
2098 }
2099 // See if we can become precise: no subklasses and no interface
2100 // (Note: We need to support verified interfaces.)
2101 if (!ik->is_interface() && !ik->has_subklass()) {
2102 //assert(!UseExactTypes, "this code should be useless with exact types");
2103 // Add a dependence; if any subclass added we need to recompile
2104 if (!ik->is_final()) {
2105 // %%% should use stronger assert_unique_concrete_subtype instead
2106 phase->C->dependencies()->assert_leaf_type(ik);
2107 }
2108 // Return precise klass
2109 return TypeKlassPtr::make(ik);
2110 }
2111
2112 // Return root of possible klass
2113 return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/);
2114 }
2115 }
2116
2117 // Check for loading klass from an array
2118 const TypeAryPtr *tary = tp->isa_aryptr();
2119 if( tary != NULL ) {
2120 ciKlass *tary_klass = tary->klass();
2121 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP
2122 && tary->offset() == oopDesc::klass_offset_in_bytes()) {
2123 if (tary->klass_is_exact()) {
2124 return TypeKlassPtr::make(tary_klass);
2125 }
2126 ciArrayKlass *ak = tary->klass()->as_array_klass();
2127 // If the klass is an object array, we defer the question to the
2128 // array component klass.
2129 if( ak->is_obj_array_klass() ) {
2130 assert( ak->is_loaded(), "" );
2131 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass();
2132 if( base_k->is_loaded() && base_k->is_instance_klass() ) {
2133 ciInstanceKlass* ik = base_k->as_instance_klass();
2134 // See if we can become precise: no subklasses and no interface
2135 if (!ik->is_interface() && !ik->has_subklass()) {
2136 //assert(!UseExactTypes, "this code should be useless with exact types");
2137 // Add a dependence; if any subclass added we need to recompile
2138 if (!ik->is_final()) {
2139 phase->C->dependencies()->assert_leaf_type(ik);
2140 }
2141 // Return precise array klass
2142 return TypeKlassPtr::make(ak);
2143 }
2144 }
2145 return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/);
2146 } else { // Found a type-array?
2147 //assert(!UseExactTypes, "this code should be useless with exact types");
2148 assert( ak->is_type_array_klass(), "" );
2149 return TypeKlassPtr::make(ak); // These are always precise
2150 }
2151 }
2152 }
2153
2154 // Check for loading klass from an array klass
2155 const TypeKlassPtr *tkls = tp->isa_klassptr();
2156 if (tkls != NULL && !StressReflectiveCode) {
2157 ciKlass* klass = tkls->klass();
2158 if( !klass->is_loaded() )
2159 return _type; // Bail out if not loaded
2160 if( klass->is_obj_array_klass() &&
2161 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) {
2162 ciKlass* elem = klass->as_obj_array_klass()->element_klass();
2163 // // Always returning precise element type is incorrect,
2164 // // e.g., element type could be object and array may contain strings
2165 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
2166
2167 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
2168 // according to the element type's subclassing.
2169 return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/);
2170 }
2171 if( klass->is_instance_klass() && tkls->klass_is_exact() &&
2172 tkls->offset() == in_bytes(Klass::super_offset())) {
2173 ciKlass* sup = klass->as_instance_klass()->super();
2174 // The field is Klass::_super. Return its (constant) value.
2175 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
2176 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR;
2177 }
2178 }
2179
2180 // Bailout case
2181 return LoadNode::Value(phase);
2182 }
2183
2184 //------------------------------Identity---------------------------------------
2185 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
2186 // Also feed through the klass in Allocate(...klass...)._klass.
2187 Node* LoadKlassNode::Identity( PhaseTransform *phase ) {
2188 return klass_identity_common(phase);
2189 }
2190
2191 Node* LoadNode::klass_identity_common(PhaseTransform *phase ) {
2192 Node* x = LoadNode::Identity(phase);
2193 if (x != this) return x;
2194
2195 // Take apart the address into an oop and and offset.
2196 // Return 'this' if we cannot.
2197 Node* adr = in(MemNode::Address);
2198 intptr_t offset = 0;
2199 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2200 if (base == NULL) return this;
2201 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
2202 if (toop == NULL) return this;
2203
2204 // We can fetch the klass directly through an AllocateNode.
2205 // This works even if the klass is not constant (clone or newArray).
2206 if (offset == oopDesc::klass_offset_in_bytes()) {
2207 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
2208 if (allocated_klass != NULL) {
2209 return allocated_klass;
2210 }
2211 }
2212
2213 // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*.
2214 // See inline_native_Class_query for occurrences of these patterns.
2215 // Java Example: x.getClass().isAssignableFrom(y)
2216 //
2217 // This improves reflective code, often making the Class
2218 // mirror go completely dead. (Current exception: Class
2219 // mirrors may appear in debug info, but we could clean them out by
2220 // introducing a new debug info operator for Klass*.java_mirror).
2221 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass()
2222 && offset == java_lang_Class::klass_offset_in_bytes()) {
2223 // We are loading a special hidden field from a Class mirror,
2224 // the field which points to its Klass or ArrayKlass metaobject.
2225 if (base->is_Load()) {
2226 Node* adr2 = base->in(MemNode::Address);
2227 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2228 if (tkls != NULL && !tkls->empty()
2229 && (tkls->klass()->is_instance_klass() ||
2230 tkls->klass()->is_array_klass())
2231 && adr2->is_AddP()
2232 ) {
2233 int mirror_field = in_bytes(Klass::java_mirror_offset());
2234 if (tkls->offset() == mirror_field) {
2235 return adr2->in(AddPNode::Base);
2236 }
2237 }
2238 }
2239 }
2240
2241 return this;
2242 }
2243
2244
2245 //------------------------------Value------------------------------------------
2246 const Type *LoadNKlassNode::Value( PhaseTransform *phase ) const {
2247 const Type *t = klass_value_common(phase);
2248 if (t == Type::TOP)
2249 return t;
2250
2251 return t->make_narrowklass();
2252 }
2253
2254 //------------------------------Identity---------------------------------------
2255 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
2256 // Also feed through the klass in Allocate(...klass...)._klass.
2257 Node* LoadNKlassNode::Identity( PhaseTransform *phase ) {
2258 Node *x = klass_identity_common(phase);
2259
2260 const Type *t = phase->type( x );
2261 if( t == Type::TOP ) return x;
2262 if( t->isa_narrowklass()) return x;
2263 assert (!t->isa_narrowoop(), "no narrow oop here");
2264
2265 return phase->transform(new EncodePKlassNode(x, t->make_narrowklass()));
2266 }
2267
2268 //------------------------------Value-----------------------------------------
2269 const Type *LoadRangeNode::Value( PhaseTransform *phase ) const {
2270 // Either input is TOP ==> the result is TOP
2271 const Type *t1 = phase->type( in(MemNode::Memory) );
2272 if( t1 == Type::TOP ) return Type::TOP;
2273 Node *adr = in(MemNode::Address);
2274 const Type *t2 = phase->type( adr );
2275 if( t2 == Type::TOP ) return Type::TOP;
2276 const TypePtr *tp = t2->is_ptr();
2277 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
2278 const TypeAryPtr *tap = tp->isa_aryptr();
2279 if( !tap ) return _type;
2280 return tap->size();
2281 }
2282
2283 //-------------------------------Ideal---------------------------------------
2284 // Feed through the length in AllocateArray(...length...)._length.
2285 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2286 Node* p = MemNode::Ideal_common(phase, can_reshape);
2287 if (p) return (p == NodeSentinel) ? NULL : p;
2288
2289 // Take apart the address into an oop and and offset.
2290 // Return 'this' if we cannot.
2291 Node* adr = in(MemNode::Address);
2292 intptr_t offset = 0;
2293 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2294 if (base == NULL) return NULL;
2295 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2296 if (tary == NULL) return NULL;
2297
2298 // We can fetch the length directly through an AllocateArrayNode.
2299 // This works even if the length is not constant (clone or newArray).
2300 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2301 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2302 if (alloc != NULL) {
2303 Node* allocated_length = alloc->Ideal_length();
2304 Node* len = alloc->make_ideal_length(tary, phase);
2305 if (allocated_length != len) {
2306 // New CastII improves on this.
2307 return len;
2308 }
2309 }
2310 }
2311
2312 return NULL;
2313 }
2314
2315 //------------------------------Identity---------------------------------------
2316 // Feed through the length in AllocateArray(...length...)._length.
2317 Node* LoadRangeNode::Identity( PhaseTransform *phase ) {
2318 Node* x = LoadINode::Identity(phase);
2319 if (x != this) return x;
2320
2321 // Take apart the address into an oop and and offset.
2322 // Return 'this' if we cannot.
2323 Node* adr = in(MemNode::Address);
2324 intptr_t offset = 0;
2325 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2326 if (base == NULL) return this;
2327 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2328 if (tary == NULL) return this;
2329
2330 // We can fetch the length directly through an AllocateArrayNode.
2331 // This works even if the length is not constant (clone or newArray).
2332 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2333 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2334 if (alloc != NULL) {
2335 Node* allocated_length = alloc->Ideal_length();
2336 // Do not allow make_ideal_length to allocate a CastII node.
2337 Node* len = alloc->make_ideal_length(tary, phase, false);
2338 if (allocated_length == len) {
2339 // Return allocated_length only if it would not be improved by a CastII.
2340 return allocated_length;
2341 }
2342 }
2343 }
2344
2345 return this;
2346
2347 }
2348
2349 //=============================================================================
2350 //---------------------------StoreNode::make-----------------------------------
2351 // Polymorphic factory method:
2352 StoreNode* StoreNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt, MemOrd mo) {
2353 assert((mo == unordered || mo == release), "unexpected");
2354 Compile* C = gvn.C;
2355 assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2356 ctl != NULL, "raw memory operations should have control edge");
2357
2358 switch (bt) {
2359 case T_BOOLEAN:
2360 case T_BYTE: return new StoreBNode(ctl, mem, adr, adr_type, val, mo);
2361 case T_INT: return new StoreINode(ctl, mem, adr, adr_type, val, mo);
2362 case T_CHAR:
2363 case T_SHORT: return new StoreCNode(ctl, mem, adr, adr_type, val, mo);
2364 case T_LONG: return new StoreLNode(ctl, mem, adr, adr_type, val, mo);
2365 case T_FLOAT: return new StoreFNode(ctl, mem, adr, adr_type, val, mo);
2366 case T_DOUBLE: return new StoreDNode(ctl, mem, adr, adr_type, val, mo);
2367 case T_METADATA:
2368 case T_ADDRESS:
2369 case T_OBJECT:
2370 #ifdef _LP64
2371 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
2372 val = gvn.transform(new EncodePNode(val, val->bottom_type()->make_narrowoop()));
2373 return new StoreNNode(ctl, mem, adr, adr_type, val, mo);
2374 } else if (adr->bottom_type()->is_ptr_to_narrowklass() ||
2375 (UseCompressedClassPointers && val->bottom_type()->isa_klassptr() &&
2376 adr->bottom_type()->isa_rawptr())) {
2377 val = gvn.transform(new EncodePKlassNode(val, val->bottom_type()->make_narrowklass()));
2378 return new StoreNKlassNode(ctl, mem, adr, adr_type, val, mo);
2379 }
2380 #endif
2381 {
2382 return new StorePNode(ctl, mem, adr, adr_type, val, mo);
2383 }
2384 }
2385 ShouldNotReachHere();
2386 return (StoreNode*)NULL;
2387 }
2388
2389 StoreLNode* StoreLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
2390 bool require_atomic = true;
2391 return new StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
2392 }
2393
2394 StoreDNode* StoreDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
2395 bool require_atomic = true;
2396 return new StoreDNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
2397 }
2398
2399
2400 //--------------------------bottom_type----------------------------------------
2401 const Type *StoreNode::bottom_type() const {
2402 return Type::MEMORY;
2403 }
2404
2405 //------------------------------hash-------------------------------------------
2406 uint StoreNode::hash() const {
2407 // unroll addition of interesting fields
2408 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2409
2410 // Since they are not commoned, do not hash them:
2411 return NO_HASH;
2412 }
2413
2414 //------------------------------Ideal------------------------------------------
2415 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
2416 // When a store immediately follows a relevant allocation/initialization,
2417 // try to capture it into the initialization, or hoist it above.
2418 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2419 Node* p = MemNode::Ideal_common(phase, can_reshape);
2420 if (p) return (p == NodeSentinel) ? NULL : p;
2421
2422 Node* mem = in(MemNode::Memory);
2423 Node* address = in(MemNode::Address);
2424
2425 // Back-to-back stores to same address? Fold em up. Generally
2426 // unsafe if I have intervening uses... Also disallowed for StoreCM
2427 // since they must follow each StoreP operation. Redundant StoreCMs
2428 // are eliminated just before matching in final_graph_reshape.
2429 if (mem->is_Store() && mem->in(MemNode::Address)->eqv_uncast(address) &&
2430 mem->Opcode() != Op_StoreCM) {
2431 // Looking at a dead closed cycle of memory?
2432 assert(mem != mem->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
2433
2434 assert(Opcode() == mem->Opcode() ||
2435 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw,
2436 "no mismatched stores, except on raw memory");
2437
2438 if (mem->outcnt() == 1 && // check for intervening uses
2439 mem->as_Store()->memory_size() <= this->memory_size()) {
2440 // If anybody other than 'this' uses 'mem', we cannot fold 'mem' away.
2441 // For example, 'mem' might be the final state at a conditional return.
2442 // Or, 'mem' might be used by some node which is live at the same time
2443 // 'this' is live, which might be unschedulable. So, require exactly
2444 // ONE user, the 'this' store, until such time as we clone 'mem' for
2445 // each of 'mem's uses (thus making the exactly-1-user-rule hold true).
2446 if (can_reshape) { // (%%% is this an anachronism?)
2447 set_req_X(MemNode::Memory, mem->in(MemNode::Memory),
2448 phase->is_IterGVN());
2449 } else {
2450 // It's OK to do this in the parser, since DU info is always accurate,
2451 // and the parser always refers to nodes via SafePointNode maps.
2452 set_req(MemNode::Memory, mem->in(MemNode::Memory));
2453 }
2454 return this;
2455 }
2456 }
2457
2458 // Capture an unaliased, unconditional, simple store into an initializer.
2459 // Or, if it is independent of the allocation, hoist it above the allocation.
2460 if (ReduceFieldZeroing && /*can_reshape &&*/
2461 mem->is_Proj() && mem->in(0)->is_Initialize()) {
2462 InitializeNode* init = mem->in(0)->as_Initialize();
2463 intptr_t offset = init->can_capture_store(this, phase, can_reshape);
2464 if (offset > 0) {
2465 Node* moved = init->capture_store(this, offset, phase, can_reshape);
2466 // If the InitializeNode captured me, it made a raw copy of me,
2467 // and I need to disappear.
2468 if (moved != NULL) {
2469 // %%% hack to ensure that Ideal returns a new node:
2470 mem = MergeMemNode::make(mem);
2471 return mem; // fold me away
2472 }
2473 }
2474 }
2475
2476 return NULL; // No further progress
2477 }
2478
2479 //------------------------------Value-----------------------------------------
2480 const Type *StoreNode::Value( PhaseTransform *phase ) const {
2481 // Either input is TOP ==> the result is TOP
2482 const Type *t1 = phase->type( in(MemNode::Memory) );
2483 if( t1 == Type::TOP ) return Type::TOP;
2484 const Type *t2 = phase->type( in(MemNode::Address) );
2485 if( t2 == Type::TOP ) return Type::TOP;
2486 const Type *t3 = phase->type( in(MemNode::ValueIn) );
2487 if( t3 == Type::TOP ) return Type::TOP;
2488 return Type::MEMORY;
2489 }
2490
2491 //------------------------------Identity---------------------------------------
2492 // Remove redundant stores:
2493 // Store(m, p, Load(m, p)) changes to m.
2494 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
2495 Node *StoreNode::Identity( PhaseTransform *phase ) {
2496 Node* mem = in(MemNode::Memory);
2497 Node* adr = in(MemNode::Address);
2498 Node* val = in(MemNode::ValueIn);
2499
2500 // Load then Store? Then the Store is useless
2501 if (val->is_Load() &&
2502 val->in(MemNode::Address)->eqv_uncast(adr) &&
2503 val->in(MemNode::Memory )->eqv_uncast(mem) &&
2504 val->as_Load()->store_Opcode() == Opcode()) {
2505 return mem;
2506 }
2507
2508 // Two stores in a row of the same value?
2509 if (mem->is_Store() &&
2510 mem->in(MemNode::Address)->eqv_uncast(adr) &&
2511 mem->in(MemNode::ValueIn)->eqv_uncast(val) &&
2512 mem->Opcode() == Opcode()) {
2513 return mem;
2514 }
2515
2516 // Store of zero anywhere into a freshly-allocated object?
2517 // Then the store is useless.
2518 // (It must already have been captured by the InitializeNode.)
2519 if (ReduceFieldZeroing && phase->type(val)->is_zero_type()) {
2520 // a newly allocated object is already all-zeroes everywhere
2521 if (mem->is_Proj() && mem->in(0)->is_Allocate()) {
2522 return mem;
2523 }
2524
2525 // the store may also apply to zero-bits in an earlier object
2526 Node* prev_mem = find_previous_store(phase);
2527 // Steps (a), (b): Walk past independent stores to find an exact match.
2528 if (prev_mem != NULL) {
2529 Node* prev_val = can_see_stored_value(prev_mem, phase);
2530 if (prev_val != NULL && phase->eqv(prev_val, val)) {
2531 // prev_val and val might differ by a cast; it would be good
2532 // to keep the more informative of the two.
2533 return mem;
2534 }
2535 }
2536 }
2537
2538 return this;
2539 }
2540
2541 //------------------------------match_edge-------------------------------------
2542 // Do we Match on this edge index or not? Match only memory & value
2543 uint StoreNode::match_edge(uint idx) const {
2544 return idx == MemNode::Address || idx == MemNode::ValueIn;
2545 }
2546
2547 //------------------------------cmp--------------------------------------------
2548 // Do not common stores up together. They generally have to be split
2549 // back up anyways, so do not bother.
2550 uint StoreNode::cmp( const Node &n ) const {
2551 return (&n == this); // Always fail except on self
2552 }
2553
2554 //------------------------------Ideal_masked_input-----------------------------
2555 // Check for a useless mask before a partial-word store
2556 // (StoreB ... (AndI valIn conIa) )
2557 // If (conIa & mask == mask) this simplifies to
2558 // (StoreB ... (valIn) )
2559 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
2560 Node *val = in(MemNode::ValueIn);
2561 if( val->Opcode() == Op_AndI ) {
2562 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2563 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
2564 set_req(MemNode::ValueIn, val->in(1));
2565 return this;
2566 }
2567 }
2568 return NULL;
2569 }
2570
2571
2572 //------------------------------Ideal_sign_extended_input----------------------
2573 // Check for useless sign-extension before a partial-word store
2574 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) )
2575 // If (conIL == conIR && conIR <= num_bits) this simplifies to
2576 // (StoreB ... (valIn) )
2577 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) {
2578 Node *val = in(MemNode::ValueIn);
2579 if( val->Opcode() == Op_RShiftI ) {
2580 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2581 if( t && t->is_con() && (t->get_con() <= num_bits) ) {
2582 Node *shl = val->in(1);
2583 if( shl->Opcode() == Op_LShiftI ) {
2584 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int();
2585 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) {
2586 set_req(MemNode::ValueIn, shl->in(1));
2587 return this;
2588 }
2589 }
2590 }
2591 }
2592 return NULL;
2593 }
2594
2595 //------------------------------value_never_loaded-----------------------------------
2596 // Determine whether there are any possible loads of the value stored.
2597 // For simplicity, we actually check if there are any loads from the
2598 // address stored to, not just for loads of the value stored by this node.
2599 //
2600 bool StoreNode::value_never_loaded( PhaseTransform *phase) const {
2601 Node *adr = in(Address);
2602 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
2603 if (adr_oop == NULL)
2604 return false;
2605 if (!adr_oop->is_known_instance_field())
2606 return false; // if not a distinct instance, there may be aliases of the address
2607 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
2608 Node *use = adr->fast_out(i);
2609 if (use->is_Load() || use->is_LoadStore()) {
2610 return false;
2611 }
2612 }
2613 return true;
2614 }
2615
2616 //=============================================================================
2617 //------------------------------Ideal------------------------------------------
2618 // If the store is from an AND mask that leaves the low bits untouched, then
2619 // we can skip the AND operation. If the store is from a sign-extension
2620 // (a left shift, then right shift) we can skip both.
2621 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
2622 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
2623 if( progress != NULL ) return progress;
2624
2625 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
2626 if( progress != NULL ) return progress;
2627
2628 // Finally check the default case
2629 return StoreNode::Ideal(phase, can_reshape);
2630 }
2631
2632 //=============================================================================
2633 //------------------------------Ideal------------------------------------------
2634 // If the store is from an AND mask that leaves the low bits untouched, then
2635 // we can skip the AND operation
2636 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
2637 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
2638 if( progress != NULL ) return progress;
2639
2640 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
2641 if( progress != NULL ) return progress;
2642
2643 // Finally check the default case
2644 return StoreNode::Ideal(phase, can_reshape);
2645 }
2646
2647 //=============================================================================
2648 //------------------------------Identity---------------------------------------
2649 Node *StoreCMNode::Identity( PhaseTransform *phase ) {
2650 // No need to card mark when storing a null ptr
2651 Node* my_store = in(MemNode::OopStore);
2652 if (my_store->is_Store()) {
2653 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) );
2654 if( t1 == TypePtr::NULL_PTR ) {
2655 return in(MemNode::Memory);
2656 }
2657 }
2658 return this;
2659 }
2660
2661 //=============================================================================
2662 //------------------------------Ideal---------------------------------------
2663 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){
2664 Node* progress = StoreNode::Ideal(phase, can_reshape);
2665 if (progress != NULL) return progress;
2666
2667 Node* my_store = in(MemNode::OopStore);
2668 if (my_store->is_MergeMem()) {
2669 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx());
2670 set_req(MemNode::OopStore, mem);
2671 return this;
2672 }
2673
2674 return NULL;
2675 }
2676
2677 //------------------------------Value-----------------------------------------
2678 const Type *StoreCMNode::Value( PhaseTransform *phase ) const {
2679 // Either input is TOP ==> the result is TOP
2680 const Type *t = phase->type( in(MemNode::Memory) );
2681 if( t == Type::TOP ) return Type::TOP;
2682 t = phase->type( in(MemNode::Address) );
2683 if( t == Type::TOP ) return Type::TOP;
2684 t = phase->type( in(MemNode::ValueIn) );
2685 if( t == Type::TOP ) return Type::TOP;
2686 // If extra input is TOP ==> the result is TOP
2687 t = phase->type( in(MemNode::OopStore) );
2688 if( t == Type::TOP ) return Type::TOP;
2689
2690 return StoreNode::Value( phase );
2691 }
2692
2693
2694 //=============================================================================
2695 //----------------------------------SCMemProjNode------------------------------
2696 const Type * SCMemProjNode::Value( PhaseTransform *phase ) const
2697 {
2698 return bottom_type();
2699 }
2700
2701 //=============================================================================
2702 //----------------------------------LoadStoreNode------------------------------
2703 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required )
2704 : Node(required),
2705 _type(rt),
2706 _adr_type(at)
2707 {
2708 init_req(MemNode::Control, c );
2709 init_req(MemNode::Memory , mem);
2710 init_req(MemNode::Address, adr);
2711 init_req(MemNode::ValueIn, val);
2712 init_class_id(Class_LoadStore);
2713 }
2714
2715 uint LoadStoreNode::ideal_reg() const {
2716 return _type->ideal_reg();
2717 }
2718
2719 bool LoadStoreNode::result_not_used() const {
2720 for( DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++ ) {
2721 Node *x = fast_out(i);
2722 if (x->Opcode() == Op_SCMemProj) continue;
2723 return false;
2724 }
2725 return true;
2726 }
2727
2728 uint LoadStoreNode::size_of() const { return sizeof(*this); }
2729
2730 //=============================================================================
2731 //----------------------------------LoadStoreConditionalNode--------------------
2732 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, NULL, TypeInt::BOOL, 5) {
2733 init_req(ExpectedIn, ex );
2734 }
2735
2736 //=============================================================================
2737 //-------------------------------adr_type--------------------------------------
2738 const TypePtr* ClearArrayNode::adr_type() const {
2739 Node *adr = in(3);
2740 if (adr == NULL) return NULL; // node is dead
2741 return MemNode::calculate_adr_type(adr->bottom_type());
2742 }
2743
2744 //------------------------------match_edge-------------------------------------
2745 // Do we Match on this edge index or not? Do not match memory
2746 uint ClearArrayNode::match_edge(uint idx) const {
2747 return idx > 1;
2748 }
2749
2750 //------------------------------Identity---------------------------------------
2751 // Clearing a zero length array does nothing
2752 Node *ClearArrayNode::Identity( PhaseTransform *phase ) {
2753 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
2754 }
2755
2756 //------------------------------Idealize---------------------------------------
2757 // Clearing a short array is faster with stores
2758 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape){
2759 const int unit = BytesPerLong;
2760 const TypeX* t = phase->type(in(2))->isa_intptr_t();
2761 if (!t) return NULL;
2762 if (!t->is_con()) return NULL;
2763 intptr_t raw_count = t->get_con();
2764 intptr_t size = raw_count;
2765 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
2766 // Clearing nothing uses the Identity call.
2767 // Negative clears are possible on dead ClearArrays
2768 // (see jck test stmt114.stmt11402.val).
2769 if (size <= 0 || size % unit != 0) return NULL;
2770 intptr_t count = size / unit;
2771 // Length too long; use fast hardware clear
2772 if (size > Matcher::init_array_short_size) return NULL;
2773 Node *mem = in(1);
2774 if( phase->type(mem)==Type::TOP ) return NULL;
2775 Node *adr = in(3);
2776 const Type* at = phase->type(adr);
2777 if( at==Type::TOP ) return NULL;
2778 const TypePtr* atp = at->isa_ptr();
2779 // adjust atp to be the correct array element address type
2780 if (atp == NULL) atp = TypePtr::BOTTOM;
2781 else atp = atp->add_offset(Type::OffsetBot);
2782 // Get base for derived pointer purposes
2783 if( adr->Opcode() != Op_AddP ) Unimplemented();
2784 Node *base = adr->in(1);
2785
2786 Node *zero = phase->makecon(TypeLong::ZERO);
2787 Node *off = phase->MakeConX(BytesPerLong);
2788 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
2789 count--;
2790 while( count-- ) {
2791 mem = phase->transform(mem);
2792 adr = phase->transform(new AddPNode(base,adr,off));
2793 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
2794 }
2795 return mem;
2796 }
2797
2798 //----------------------------step_through----------------------------------
2799 // Return allocation input memory edge if it is different instance
2800 // or itself if it is the one we are looking for.
2801 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) {
2802 Node* n = *np;
2803 assert(n->is_ClearArray(), "sanity");
2804 intptr_t offset;
2805 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
2806 // This method is called only before Allocate nodes are expanded
2807 // during macro nodes expansion. Before that ClearArray nodes are
2808 // only generated in PhaseMacroExpand::generate_arraycopy() (before
2809 // Allocate nodes are expanded) which follows allocations.
2810 assert(alloc != NULL, "should have allocation");
2811 if (alloc->_idx == instance_id) {
2812 // Can not bypass initialization of the instance we are looking for.
2813 return false;
2814 }
2815 // Otherwise skip it.
2816 InitializeNode* init = alloc->initialization();
2817 if (init != NULL)
2818 *np = init->in(TypeFunc::Memory);
2819 else
2820 *np = alloc->in(TypeFunc::Memory);
2821 return true;
2822 }
2823
2824 //----------------------------clear_memory-------------------------------------
2825 // Generate code to initialize object storage to zero.
2826 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2827 intptr_t start_offset,
2828 Node* end_offset,
2829 PhaseGVN* phase) {
2830 intptr_t offset = start_offset;
2831
2832 int unit = BytesPerLong;
2833 if ((offset % unit) != 0) {
2834 Node* adr = new AddPNode(dest, dest, phase->MakeConX(offset));
2835 adr = phase->transform(adr);
2836 const TypePtr* atp = TypeRawPtr::BOTTOM;
2837 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
2838 mem = phase->transform(mem);
2839 offset += BytesPerInt;
2840 }
2841 assert((offset % unit) == 0, "");
2842
2843 // Initialize the remaining stuff, if any, with a ClearArray.
2844 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase);
2845 }
2846
2847 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2848 Node* start_offset,
2849 Node* end_offset,
2850 PhaseGVN* phase) {
2851 if (start_offset == end_offset) {
2852 // nothing to do
2853 return mem;
2854 }
2855
2856 int unit = BytesPerLong;
2857 Node* zbase = start_offset;
2858 Node* zend = end_offset;
2859
2860 // Scale to the unit required by the CPU:
2861 if (!Matcher::init_array_count_is_in_bytes) {
2862 Node* shift = phase->intcon(exact_log2(unit));
2863 zbase = phase->transform(new URShiftXNode(zbase, shift) );
2864 zend = phase->transform(new URShiftXNode(zend, shift) );
2865 }
2866
2867 // Bulk clear double-words
2868 Node* zsize = phase->transform(new SubXNode(zend, zbase) );
2869 Node* adr = phase->transform(new AddPNode(dest, dest, start_offset) );
2870 mem = new ClearArrayNode(ctl, mem, zsize, adr);
2871 return phase->transform(mem);
2872 }
2873
2874 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2875 intptr_t start_offset,
2876 intptr_t end_offset,
2877 PhaseGVN* phase) {
2878 if (start_offset == end_offset) {
2879 // nothing to do
2880 return mem;
2881 }
2882
2883 assert((end_offset % BytesPerInt) == 0, "odd end offset");
2884 intptr_t done_offset = end_offset;
2885 if ((done_offset % BytesPerLong) != 0) {
2886 done_offset -= BytesPerInt;
2887 }
2888 if (done_offset > start_offset) {
2889 mem = clear_memory(ctl, mem, dest,
2890 start_offset, phase->MakeConX(done_offset), phase);
2891 }
2892 if (done_offset < end_offset) { // emit the final 32-bit store
2893 Node* adr = new AddPNode(dest, dest, phase->MakeConX(done_offset));
2894 adr = phase->transform(adr);
2895 const TypePtr* atp = TypeRawPtr::BOTTOM;
2896 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
2897 mem = phase->transform(mem);
2898 done_offset += BytesPerInt;
2899 }
2900 assert(done_offset == end_offset, "");
2901 return mem;
2902 }
2903
2904 //=============================================================================
2905 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
2906 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)),
2907 _adr_type(C->get_adr_type(alias_idx))
2908 {
2909 init_class_id(Class_MemBar);
2910 Node* top = C->top();
2911 init_req(TypeFunc::I_O,top);
2912 init_req(TypeFunc::FramePtr,top);
2913 init_req(TypeFunc::ReturnAdr,top);
2914 if (precedent != NULL)
2915 init_req(TypeFunc::Parms, precedent);
2916 }
2917
2918 //------------------------------cmp--------------------------------------------
2919 uint MemBarNode::hash() const { return NO_HASH; }
2920 uint MemBarNode::cmp( const Node &n ) const {
2921 return (&n == this); // Always fail except on self
2922 }
2923
2924 //------------------------------make-------------------------------------------
2925 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
2926 switch (opcode) {
2927 case Op_MemBarAcquire: return new MemBarAcquireNode(C, atp, pn);
2928 case Op_LoadFence: return new LoadFenceNode(C, atp, pn);
2929 case Op_MemBarRelease: return new MemBarReleaseNode(C, atp, pn);
2930 case Op_StoreFence: return new StoreFenceNode(C, atp, pn);
2931 case Op_MemBarAcquireLock: return new MemBarAcquireLockNode(C, atp, pn);
2932 case Op_MemBarReleaseLock: return new MemBarReleaseLockNode(C, atp, pn);
2933 case Op_MemBarVolatile: return new MemBarVolatileNode(C, atp, pn);
2934 case Op_MemBarCPUOrder: return new MemBarCPUOrderNode(C, atp, pn);
2935 case Op_Initialize: return new InitializeNode(C, atp, pn);
2936 case Op_MemBarStoreStore: return new MemBarStoreStoreNode(C, atp, pn);
2937 default: ShouldNotReachHere(); return NULL;
2938 }
2939 }
2940
2941 //------------------------------Ideal------------------------------------------
2942 // Return a node which is more "ideal" than the current node. Strip out
2943 // control copies
2944 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2945 if (remove_dead_region(phase, can_reshape)) return this;
2946 // Don't bother trying to transform a dead node
2947 if (in(0) && in(0)->is_top()) {
2948 return NULL;
2949 }
2950
2951 bool progress = false;
2952 // Eliminate volatile MemBars for scalar replaced objects.
2953 if (can_reshape && req() == (Precedent+1)) {
2954 bool eliminate = false;
2955 int opc = Opcode();
2956 if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) {
2957 // Volatile field loads and stores.
2958 Node* my_mem = in(MemBarNode::Precedent);
2959 // The MembarAquire may keep an unused LoadNode alive through the Precedent edge
2960 if ((my_mem != NULL) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) {
2961 // if the Precedent is a decodeN and its input (a Load) is used at more than one place,
2962 // replace this Precedent (decodeN) with the Load instead.
2963 if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1)) {
2964 Node* load_node = my_mem->in(1);
2965 set_req(MemBarNode::Precedent, load_node);
2966 phase->is_IterGVN()->_worklist.push(my_mem);
2967 my_mem = load_node;
2968 } else {
2969 assert(my_mem->unique_out() == this, "sanity");
2970 del_req(Precedent);
2971 phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later
2972 my_mem = NULL;
2973 }
2974 progress = true;
2975 }
2976 if (my_mem != NULL && my_mem->is_Mem()) {
2977 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
2978 // Check for scalar replaced object reference.
2979 if( t_oop != NULL && t_oop->is_known_instance_field() &&
2980 t_oop->offset() != Type::OffsetBot &&
2981 t_oop->offset() != Type::OffsetTop) {
2982 eliminate = true;
2983 }
2984 }
2985 } else if (opc == Op_MemBarRelease) {
2986 // Final field stores.
2987 Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent), phase);
2988 if ((alloc != NULL) && alloc->is_Allocate() &&
2989 alloc->as_Allocate()->_is_non_escaping) {
2990 // The allocated object does not escape.
2991 eliminate = true;
2992 }
2993 }
2994 if (eliminate) {
2995 // Replace MemBar projections by its inputs.
2996 PhaseIterGVN* igvn = phase->is_IterGVN();
2997 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
2998 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
2999 // Must return either the original node (now dead) or a new node
3000 // (Do not return a top here, since that would break the uniqueness of top.)
3001 return new ConINode(TypeInt::ZERO);
3002 }
3003 }
3004 return progress ? this : NULL;
3005 }
3006
3007 //------------------------------Value------------------------------------------
3008 const Type *MemBarNode::Value( PhaseTransform *phase ) const {
3009 if( !in(0) ) return Type::TOP;
3010 if( phase->type(in(0)) == Type::TOP )
3011 return Type::TOP;
3012 return TypeTuple::MEMBAR;
3013 }
3014
3015 //------------------------------match------------------------------------------
3016 // Construct projections for memory.
3017 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) {
3018 switch (proj->_con) {
3019 case TypeFunc::Control:
3020 case TypeFunc::Memory:
3021 return new MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
3022 }
3023 ShouldNotReachHere();
3024 return NULL;
3025 }
3026
3027 //===========================InitializeNode====================================
3028 // SUMMARY:
3029 // This node acts as a memory barrier on raw memory, after some raw stores.
3030 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
3031 // The Initialize can 'capture' suitably constrained stores as raw inits.
3032 // It can coalesce related raw stores into larger units (called 'tiles').
3033 // It can avoid zeroing new storage for memory units which have raw inits.
3034 // At macro-expansion, it is marked 'complete', and does not optimize further.
3035 //
3036 // EXAMPLE:
3037 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
3038 // ctl = incoming control; mem* = incoming memory
3039 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
3040 // First allocate uninitialized memory and fill in the header:
3041 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
3042 // ctl := alloc.Control; mem* := alloc.Memory*
3043 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
3044 // Then initialize to zero the non-header parts of the raw memory block:
3045 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
3046 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
3047 // After the initialize node executes, the object is ready for service:
3048 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
3049 // Suppose its body is immediately initialized as {1,2}:
3050 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3051 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3052 // mem.SLICE(#short[*]) := store2
3053 //
3054 // DETAILS:
3055 // An InitializeNode collects and isolates object initialization after
3056 // an AllocateNode and before the next possible safepoint. As a
3057 // memory barrier (MemBarNode), it keeps critical stores from drifting
3058 // down past any safepoint or any publication of the allocation.
3059 // Before this barrier, a newly-allocated object may have uninitialized bits.
3060 // After this barrier, it may be treated as a real oop, and GC is allowed.
3061 //
3062 // The semantics of the InitializeNode include an implicit zeroing of
3063 // the new object from object header to the end of the object.
3064 // (The object header and end are determined by the AllocateNode.)
3065 //
3066 // Certain stores may be added as direct inputs to the InitializeNode.
3067 // These stores must update raw memory, and they must be to addresses
3068 // derived from the raw address produced by AllocateNode, and with
3069 // a constant offset. They must be ordered by increasing offset.
3070 // The first one is at in(RawStores), the last at in(req()-1).
3071 // Unlike most memory operations, they are not linked in a chain,
3072 // but are displayed in parallel as users of the rawmem output of
3073 // the allocation.
3074 //
3075 // (See comments in InitializeNode::capture_store, which continue
3076 // the example given above.)
3077 //
3078 // When the associated Allocate is macro-expanded, the InitializeNode
3079 // may be rewritten to optimize collected stores. A ClearArrayNode
3080 // may also be created at that point to represent any required zeroing.
3081 // The InitializeNode is then marked 'complete', prohibiting further
3082 // capturing of nearby memory operations.
3083 //
3084 // During macro-expansion, all captured initializations which store
3085 // constant values of 32 bits or smaller are coalesced (if advantageous)
3086 // into larger 'tiles' 32 or 64 bits. This allows an object to be
3087 // initialized in fewer memory operations. Memory words which are
3088 // covered by neither tiles nor non-constant stores are pre-zeroed
3089 // by explicit stores of zero. (The code shape happens to do all
3090 // zeroing first, then all other stores, with both sequences occurring
3091 // in order of ascending offsets.)
3092 //
3093 // Alternatively, code may be inserted between an AllocateNode and its
3094 // InitializeNode, to perform arbitrary initialization of the new object.
3095 // E.g., the object copying intrinsics insert complex data transfers here.
3096 // The initialization must then be marked as 'complete' disable the
3097 // built-in zeroing semantics and the collection of initializing stores.
3098 //
3099 // While an InitializeNode is incomplete, reads from the memory state
3100 // produced by it are optimizable if they match the control edge and
3101 // new oop address associated with the allocation/initialization.
3102 // They return a stored value (if the offset matches) or else zero.
3103 // A write to the memory state, if it matches control and address,
3104 // and if it is to a constant offset, may be 'captured' by the
3105 // InitializeNode. It is cloned as a raw memory operation and rewired
3106 // inside the initialization, to the raw oop produced by the allocation.
3107 // Operations on addresses which are provably distinct (e.g., to
3108 // other AllocateNodes) are allowed to bypass the initialization.
3109 //
3110 // The effect of all this is to consolidate object initialization
3111 // (both arrays and non-arrays, both piecewise and bulk) into a
3112 // single location, where it can be optimized as a unit.
3113 //
3114 // Only stores with an offset less than TrackedInitializationLimit words
3115 // will be considered for capture by an InitializeNode. This puts a
3116 // reasonable limit on the complexity of optimized initializations.
3117
3118 //---------------------------InitializeNode------------------------------------
3119 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
3120 : _is_complete(Incomplete), _does_not_escape(false),
3121 MemBarNode(C, adr_type, rawoop)
3122 {
3123 init_class_id(Class_Initialize);
3124
3125 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
3126 assert(in(RawAddress) == rawoop, "proper init");
3127 // Note: allocation() can be NULL, for secondary initialization barriers
3128 }
3129
3130 // Since this node is not matched, it will be processed by the
3131 // register allocator. Declare that there are no constraints
3132 // on the allocation of the RawAddress edge.
3133 const RegMask &InitializeNode::in_RegMask(uint idx) const {
3134 // This edge should be set to top, by the set_complete. But be conservative.
3135 if (idx == InitializeNode::RawAddress)
3136 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
3137 return RegMask::Empty;
3138 }
3139
3140 Node* InitializeNode::memory(uint alias_idx) {
3141 Node* mem = in(Memory);
3142 if (mem->is_MergeMem()) {
3143 return mem->as_MergeMem()->memory_at(alias_idx);
3144 } else {
3145 // incoming raw memory is not split
3146 return mem;
3147 }
3148 }
3149
3150 bool InitializeNode::is_non_zero() {
3151 if (is_complete()) return false;
3152 remove_extra_zeroes();
3153 return (req() > RawStores);
3154 }
3155
3156 void InitializeNode::set_complete(PhaseGVN* phase) {
3157 assert(!is_complete(), "caller responsibility");
3158 _is_complete = Complete;
3159
3160 // After this node is complete, it contains a bunch of
3161 // raw-memory initializations. There is no need for
3162 // it to have anything to do with non-raw memory effects.
3163 // Therefore, tell all non-raw users to re-optimize themselves,
3164 // after skipping the memory effects of this initialization.
3165 PhaseIterGVN* igvn = phase->is_IterGVN();
3166 if (igvn) igvn->add_users_to_worklist(this);
3167 }
3168
3169 // convenience function
3170 // return false if the init contains any stores already
3171 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
3172 InitializeNode* init = initialization();
3173 if (init == NULL || init->is_complete()) return false;
3174 init->remove_extra_zeroes();
3175 // for now, if this allocation has already collected any inits, bail:
3176 if (init->is_non_zero()) return false;
3177 init->set_complete(phase);
3178 return true;
3179 }
3180
3181 void InitializeNode::remove_extra_zeroes() {
3182 if (req() == RawStores) return;
3183 Node* zmem = zero_memory();
3184 uint fill = RawStores;
3185 for (uint i = fill; i < req(); i++) {
3186 Node* n = in(i);
3187 if (n->is_top() || n == zmem) continue; // skip
3188 if (fill < i) set_req(fill, n); // compact
3189 ++fill;
3190 }
3191 // delete any empty spaces created:
3192 while (fill < req()) {
3193 del_req(fill);
3194 }
3195 }
3196
3197 // Helper for remembering which stores go with which offsets.
3198 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) {
3199 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
3200 intptr_t offset = -1;
3201 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
3202 phase, offset);
3203 if (base == NULL) return -1; // something is dead,
3204 if (offset < 0) return -1; // dead, dead
3205 return offset;
3206 }
3207
3208 // Helper for proving that an initialization expression is
3209 // "simple enough" to be folded into an object initialization.
3210 // Attempts to prove that a store's initial value 'n' can be captured
3211 // within the initialization without creating a vicious cycle, such as:
3212 // { Foo p = new Foo(); p.next = p; }
3213 // True for constants and parameters and small combinations thereof.
3214 bool InitializeNode::detect_init_independence(Node* n, int& count) {
3215 if (n == NULL) return true; // (can this really happen?)
3216 if (n->is_Proj()) n = n->in(0);
3217 if (n == this) return false; // found a cycle
3218 if (n->is_Con()) return true;
3219 if (n->is_Start()) return true; // params, etc., are OK
3220 if (n->is_Root()) return true; // even better
3221
3222 Node* ctl = n->in(0);
3223 if (ctl != NULL && !ctl->is_top()) {
3224 if (ctl->is_Proj()) ctl = ctl->in(0);
3225 if (ctl == this) return false;
3226
3227 // If we already know that the enclosing memory op is pinned right after
3228 // the init, then any control flow that the store has picked up
3229 // must have preceded the init, or else be equal to the init.
3230 // Even after loop optimizations (which might change control edges)
3231 // a store is never pinned *before* the availability of its inputs.
3232 if (!MemNode::all_controls_dominate(n, this))
3233 return false; // failed to prove a good control
3234 }
3235
3236 // Check data edges for possible dependencies on 'this'.
3237 if ((count += 1) > 20) return false; // complexity limit
3238 for (uint i = 1; i < n->req(); i++) {
3239 Node* m = n->in(i);
3240 if (m == NULL || m == n || m->is_top()) continue;
3241 uint first_i = n->find_edge(m);
3242 if (i != first_i) continue; // process duplicate edge just once
3243 if (!detect_init_independence(m, count)) {
3244 return false;
3245 }
3246 }
3247
3248 return true;
3249 }
3250
3251 // Here are all the checks a Store must pass before it can be moved into
3252 // an initialization. Returns zero if a check fails.
3253 // On success, returns the (constant) offset to which the store applies,
3254 // within the initialized memory.
3255 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase, bool can_reshape) {
3256 const int FAIL = 0;
3257 if (st->req() != MemNode::ValueIn + 1)
3258 return FAIL; // an inscrutable StoreNode (card mark?)
3259 Node* ctl = st->in(MemNode::Control);
3260 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this))
3261 return FAIL; // must be unconditional after the initialization
3262 Node* mem = st->in(MemNode::Memory);
3263 if (!(mem->is_Proj() && mem->in(0) == this))
3264 return FAIL; // must not be preceded by other stores
3265 Node* adr = st->in(MemNode::Address);
3266 intptr_t offset;
3267 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
3268 if (alloc == NULL)
3269 return FAIL; // inscrutable address
3270 if (alloc != allocation())
3271 return FAIL; // wrong allocation! (store needs to float up)
3272 Node* val = st->in(MemNode::ValueIn);
3273 int complexity_count = 0;
3274 if (!detect_init_independence(val, complexity_count))
3275 return FAIL; // stored value must be 'simple enough'
3276
3277 // The Store can be captured only if nothing after the allocation
3278 // and before the Store is using the memory location that the store
3279 // overwrites.
3280 bool failed = false;
3281 // If is_complete_with_arraycopy() is true the shape of the graph is
3282 // well defined and is safe so no need for extra checks.
3283 if (!is_complete_with_arraycopy()) {
3284 // We are going to look at each use of the memory state following
3285 // the allocation to make sure nothing reads the memory that the
3286 // Store writes.
3287 const TypePtr* t_adr = phase->type(adr)->isa_ptr();
3288 int alias_idx = phase->C->get_alias_index(t_adr);
3289 ResourceMark rm;
3290 Unique_Node_List mems;
3291 mems.push(mem);
3292 Node* unique_merge = NULL;
3293 for (uint next = 0; next < mems.size(); ++next) {
3294 Node *m = mems.at(next);
3295 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
3296 Node *n = m->fast_out(j);
3297 if (n->outcnt() == 0) {
3298 continue;
3299 }
3300 if (n == st) {
3301 continue;
3302 } else if (n->in(0) != NULL && n->in(0) != ctl) {
3303 // If the control of this use is different from the control
3304 // of the Store which is right after the InitializeNode then
3305 // this node cannot be between the InitializeNode and the
3306 // Store.
3307 continue;
3308 } else if (n->is_MergeMem()) {
3309 if (n->as_MergeMem()->memory_at(alias_idx) == m) {
3310 // We can hit a MergeMemNode (that will likely go away
3311 // later) that is a direct use of the memory state
3312 // following the InitializeNode on the same slice as the
3313 // store node that we'd like to capture. We need to check
3314 // the uses of the MergeMemNode.
3315 mems.push(n);
3316 }
3317 } else if (n->is_Mem()) {
3318 Node* other_adr = n->in(MemNode::Address);
3319 if (other_adr == adr) {
3320 failed = true;
3321 break;
3322 } else {
3323 const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr();
3324 if (other_t_adr != NULL) {
3325 int other_alias_idx = phase->C->get_alias_index(other_t_adr);
3326 if (other_alias_idx == alias_idx) {
3327 // A load from the same memory slice as the store right
3328 // after the InitializeNode. We check the control of the
3329 // object/array that is loaded from. If it's the same as
3330 // the store control then we cannot capture the store.
3331 assert(!n->is_Store(), "2 stores to same slice on same control?");
3332 Node* base = other_adr;
3333 assert(base->is_AddP(), err_msg_res("should be addp but is %s", base->Name()));
3334 base = base->in(AddPNode::Base);
3335 if (base != NULL) {
3336 base = base->uncast();
3337 if (base->is_Proj() && base->in(0) == alloc) {
3338 failed = true;
3339 break;
3340 }
3341 }
3342 }
3343 }
3344 }
3345 } else {
3346 failed = true;
3347 break;
3348 }
3349 }
3350 }
3351 }
3352 if (failed) {
3353 if (!can_reshape) {
3354 // We decided we couldn't capture the store during parsing. We
3355 // should try again during the next IGVN once the graph is
3356 // cleaner.
3357 phase->C->record_for_igvn(st);
3358 }
3359 return FAIL;
3360 }
3361
3362 return offset; // success
3363 }
3364
3365 // Find the captured store in(i) which corresponds to the range
3366 // [start..start+size) in the initialized object.
3367 // If there is one, return its index i. If there isn't, return the
3368 // negative of the index where it should be inserted.
3369 // Return 0 if the queried range overlaps an initialization boundary
3370 // or if dead code is encountered.
3371 // If size_in_bytes is zero, do not bother with overlap checks.
3372 int InitializeNode::captured_store_insertion_point(intptr_t start,
3373 int size_in_bytes,
3374 PhaseTransform* phase) {
3375 const int FAIL = 0, MAX_STORE = BytesPerLong;
3376
3377 if (is_complete())
3378 return FAIL; // arraycopy got here first; punt
3379
3380 assert(allocation() != NULL, "must be present");
3381
3382 // no negatives, no header fields:
3383 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
3384
3385 // after a certain size, we bail out on tracking all the stores:
3386 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3387 if (start >= ti_limit) return FAIL;
3388
3389 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
3390 if (i >= limit) return -(int)i; // not found; here is where to put it
3391
3392 Node* st = in(i);
3393 intptr_t st_off = get_store_offset(st, phase);
3394 if (st_off < 0) {
3395 if (st != zero_memory()) {
3396 return FAIL; // bail out if there is dead garbage
3397 }
3398 } else if (st_off > start) {
3399 // ...we are done, since stores are ordered
3400 if (st_off < start + size_in_bytes) {
3401 return FAIL; // the next store overlaps
3402 }
3403 return -(int)i; // not found; here is where to put it
3404 } else if (st_off < start) {
3405 if (size_in_bytes != 0 &&
3406 start < st_off + MAX_STORE &&
3407 start < st_off + st->as_Store()->memory_size()) {
3408 return FAIL; // the previous store overlaps
3409 }
3410 } else {
3411 if (size_in_bytes != 0 &&
3412 st->as_Store()->memory_size() != size_in_bytes) {
3413 return FAIL; // mismatched store size
3414 }
3415 return i;
3416 }
3417
3418 ++i;
3419 }
3420 }
3421
3422 // Look for a captured store which initializes at the offset 'start'
3423 // with the given size. If there is no such store, and no other
3424 // initialization interferes, then return zero_memory (the memory
3425 // projection of the AllocateNode).
3426 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
3427 PhaseTransform* phase) {
3428 assert(stores_are_sane(phase), "");
3429 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3430 if (i == 0) {
3431 return NULL; // something is dead
3432 } else if (i < 0) {
3433 return zero_memory(); // just primordial zero bits here
3434 } else {
3435 Node* st = in(i); // here is the store at this position
3436 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
3437 return st;
3438 }
3439 }
3440
3441 // Create, as a raw pointer, an address within my new object at 'offset'.
3442 Node* InitializeNode::make_raw_address(intptr_t offset,
3443 PhaseTransform* phase) {
3444 Node* addr = in(RawAddress);
3445 if (offset != 0) {
3446 Compile* C = phase->C;
3447 addr = phase->transform( new AddPNode(C->top(), addr,
3448 phase->MakeConX(offset)) );
3449 }
3450 return addr;
3451 }
3452
3453 // Clone the given store, converting it into a raw store
3454 // initializing a field or element of my new object.
3455 // Caller is responsible for retiring the original store,
3456 // with subsume_node or the like.
3457 //
3458 // From the example above InitializeNode::InitializeNode,
3459 // here are the old stores to be captured:
3460 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3461 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3462 //
3463 // Here is the changed code; note the extra edges on init:
3464 // alloc = (Allocate ...)
3465 // rawoop = alloc.RawAddress
3466 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
3467 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
3468 // init = (Initialize alloc.Control alloc.Memory rawoop
3469 // rawstore1 rawstore2)
3470 //
3471 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
3472 PhaseTransform* phase, bool can_reshape) {
3473 assert(stores_are_sane(phase), "");
3474
3475 if (start < 0) return NULL;
3476 assert(can_capture_store(st, phase, can_reshape) == start, "sanity");
3477
3478 Compile* C = phase->C;
3479 int size_in_bytes = st->memory_size();
3480 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3481 if (i == 0) return NULL; // bail out
3482 Node* prev_mem = NULL; // raw memory for the captured store
3483 if (i > 0) {
3484 prev_mem = in(i); // there is a pre-existing store under this one
3485 set_req(i, C->top()); // temporarily disconnect it
3486 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
3487 } else {
3488 i = -i; // no pre-existing store
3489 prev_mem = zero_memory(); // a slice of the newly allocated object
3490 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
3491 set_req(--i, C->top()); // reuse this edge; it has been folded away
3492 else
3493 ins_req(i, C->top()); // build a new edge
3494 }
3495 Node* new_st = st->clone();
3496 new_st->set_req(MemNode::Control, in(Control));
3497 new_st->set_req(MemNode::Memory, prev_mem);
3498 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
3499 new_st = phase->transform(new_st);
3500
3501 // At this point, new_st might have swallowed a pre-existing store
3502 // at the same offset, or perhaps new_st might have disappeared,
3503 // if it redundantly stored the same value (or zero to fresh memory).
3504
3505 // In any case, wire it in:
3506 phase->igvn_rehash_node_delayed(this);
3507 set_req(i, new_st);
3508
3509 // The caller may now kill the old guy.
3510 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
3511 assert(check_st == new_st || check_st == NULL, "must be findable");
3512 assert(!is_complete(), "");
3513 return new_st;
3514 }
3515
3516 static bool store_constant(jlong* tiles, int num_tiles,
3517 intptr_t st_off, int st_size,
3518 jlong con) {
3519 if ((st_off & (st_size-1)) != 0)
3520 return false; // strange store offset (assume size==2**N)
3521 address addr = (address)tiles + st_off;
3522 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
3523 switch (st_size) {
3524 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
3525 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
3526 case sizeof(jint): *(jint*) addr = (jint) con; break;
3527 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
3528 default: return false; // strange store size (detect size!=2**N here)
3529 }
3530 return true; // return success to caller
3531 }
3532
3533 // Coalesce subword constants into int constants and possibly
3534 // into long constants. The goal, if the CPU permits,
3535 // is to initialize the object with a small number of 64-bit tiles.
3536 // Also, convert floating-point constants to bit patterns.
3537 // Non-constants are not relevant to this pass.
3538 //
3539 // In terms of the running example on InitializeNode::InitializeNode
3540 // and InitializeNode::capture_store, here is the transformation
3541 // of rawstore1 and rawstore2 into rawstore12:
3542 // alloc = (Allocate ...)
3543 // rawoop = alloc.RawAddress
3544 // tile12 = 0x00010002
3545 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
3546 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
3547 //
3548 void
3549 InitializeNode::coalesce_subword_stores(intptr_t header_size,
3550 Node* size_in_bytes,
3551 PhaseGVN* phase) {
3552 Compile* C = phase->C;
3553
3554 assert(stores_are_sane(phase), "");
3555 // Note: After this pass, they are not completely sane,
3556 // since there may be some overlaps.
3557
3558 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
3559
3560 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3561 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
3562 size_limit = MIN2(size_limit, ti_limit);
3563 size_limit = align_size_up(size_limit, BytesPerLong);
3564 int num_tiles = size_limit / BytesPerLong;
3565
3566 // allocate space for the tile map:
3567 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
3568 jlong tiles_buf[small_len];
3569 Node* nodes_buf[small_len];
3570 jlong inits_buf[small_len];
3571 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
3572 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3573 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
3574 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
3575 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
3576 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3577 // tiles: exact bitwise model of all primitive constants
3578 // nodes: last constant-storing node subsumed into the tiles model
3579 // inits: which bytes (in each tile) are touched by any initializations
3580
3581 //// Pass A: Fill in the tile model with any relevant stores.
3582
3583 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
3584 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
3585 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
3586 Node* zmem = zero_memory(); // initially zero memory state
3587 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3588 Node* st = in(i);
3589 intptr_t st_off = get_store_offset(st, phase);
3590
3591 // Figure out the store's offset and constant value:
3592 if (st_off < header_size) continue; //skip (ignore header)
3593 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
3594 int st_size = st->as_Store()->memory_size();
3595 if (st_off + st_size > size_limit) break;
3596
3597 // Record which bytes are touched, whether by constant or not.
3598 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
3599 continue; // skip (strange store size)
3600
3601 const Type* val = phase->type(st->in(MemNode::ValueIn));
3602 if (!val->singleton()) continue; //skip (non-con store)
3603 BasicType type = val->basic_type();
3604
3605 jlong con = 0;
3606 switch (type) {
3607 case T_INT: con = val->is_int()->get_con(); break;
3608 case T_LONG: con = val->is_long()->get_con(); break;
3609 case T_FLOAT: con = jint_cast(val->getf()); break;
3610 case T_DOUBLE: con = jlong_cast(val->getd()); break;
3611 default: continue; //skip (odd store type)
3612 }
3613
3614 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
3615 st->Opcode() == Op_StoreL) {
3616 continue; // This StoreL is already optimal.
3617 }
3618
3619 // Store down the constant.
3620 store_constant(tiles, num_tiles, st_off, st_size, con);
3621
3622 intptr_t j = st_off >> LogBytesPerLong;
3623
3624 if (type == T_INT && st_size == BytesPerInt
3625 && (st_off & BytesPerInt) == BytesPerInt) {
3626 jlong lcon = tiles[j];
3627 if (!Matcher::isSimpleConstant64(lcon) &&
3628 st->Opcode() == Op_StoreI) {
3629 // This StoreI is already optimal by itself.
3630 jint* intcon = (jint*) &tiles[j];
3631 intcon[1] = 0; // undo the store_constant()
3632
3633 // If the previous store is also optimal by itself, back up and
3634 // undo the action of the previous loop iteration... if we can.
3635 // But if we can't, just let the previous half take care of itself.
3636 st = nodes[j];
3637 st_off -= BytesPerInt;
3638 con = intcon[0];
3639 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) {
3640 assert(st_off >= header_size, "still ignoring header");
3641 assert(get_store_offset(st, phase) == st_off, "must be");
3642 assert(in(i-1) == zmem, "must be");
3643 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
3644 assert(con == tcon->is_int()->get_con(), "must be");
3645 // Undo the effects of the previous loop trip, which swallowed st:
3646 intcon[0] = 0; // undo store_constant()
3647 set_req(i-1, st); // undo set_req(i, zmem)
3648 nodes[j] = NULL; // undo nodes[j] = st
3649 --old_subword; // undo ++old_subword
3650 }
3651 continue; // This StoreI is already optimal.
3652 }
3653 }
3654
3655 // This store is not needed.
3656 set_req(i, zmem);
3657 nodes[j] = st; // record for the moment
3658 if (st_size < BytesPerLong) // something has changed
3659 ++old_subword; // includes int/float, but who's counting...
3660 else ++old_long;
3661 }
3662
3663 if ((old_subword + old_long) == 0)
3664 return; // nothing more to do
3665
3666 //// Pass B: Convert any non-zero tiles into optimal constant stores.
3667 // Be sure to insert them before overlapping non-constant stores.
3668 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
3669 for (int j = 0; j < num_tiles; j++) {
3670 jlong con = tiles[j];
3671 jlong init = inits[j];
3672 if (con == 0) continue;
3673 jint con0, con1; // split the constant, address-wise
3674 jint init0, init1; // split the init map, address-wise
3675 { union { jlong con; jint intcon[2]; } u;
3676 u.con = con;
3677 con0 = u.intcon[0];
3678 con1 = u.intcon[1];
3679 u.con = init;
3680 init0 = u.intcon[0];
3681 init1 = u.intcon[1];
3682 }
3683
3684 Node* old = nodes[j];
3685 assert(old != NULL, "need the prior store");
3686 intptr_t offset = (j * BytesPerLong);
3687
3688 bool split = !Matcher::isSimpleConstant64(con);
3689
3690 if (offset < header_size) {
3691 assert(offset + BytesPerInt >= header_size, "second int counts");
3692 assert(*(jint*)&tiles[j] == 0, "junk in header");
3693 split = true; // only the second word counts
3694 // Example: int a[] = { 42 ... }
3695 } else if (con0 == 0 && init0 == -1) {
3696 split = true; // first word is covered by full inits
3697 // Example: int a[] = { ... foo(), 42 ... }
3698 } else if (con1 == 0 && init1 == -1) {
3699 split = true; // second word is covered by full inits
3700 // Example: int a[] = { ... 42, foo() ... }
3701 }
3702
3703 // Here's a case where init0 is neither 0 nor -1:
3704 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
3705 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
3706 // In this case the tile is not split; it is (jlong)42.
3707 // The big tile is stored down, and then the foo() value is inserted.
3708 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
3709
3710 Node* ctl = old->in(MemNode::Control);
3711 Node* adr = make_raw_address(offset, phase);
3712 const TypePtr* atp = TypeRawPtr::BOTTOM;
3713
3714 // One or two coalesced stores to plop down.
3715 Node* st[2];
3716 intptr_t off[2];
3717 int nst = 0;
3718 if (!split) {
3719 ++new_long;
3720 off[nst] = offset;
3721 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3722 phase->longcon(con), T_LONG, MemNode::unordered);
3723 } else {
3724 // Omit either if it is a zero.
3725 if (con0 != 0) {
3726 ++new_int;
3727 off[nst] = offset;
3728 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3729 phase->intcon(con0), T_INT, MemNode::unordered);
3730 }
3731 if (con1 != 0) {
3732 ++new_int;
3733 offset += BytesPerInt;
3734 adr = make_raw_address(offset, phase);
3735 off[nst] = offset;
3736 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3737 phase->intcon(con1), T_INT, MemNode::unordered);
3738 }
3739 }
3740
3741 // Insert second store first, then the first before the second.
3742 // Insert each one just before any overlapping non-constant stores.
3743 while (nst > 0) {
3744 Node* st1 = st[--nst];
3745 C->copy_node_notes_to(st1, old);
3746 st1 = phase->transform(st1);
3747 offset = off[nst];
3748 assert(offset >= header_size, "do not smash header");
3749 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
3750 guarantee(ins_idx != 0, "must re-insert constant store");
3751 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
3752 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
3753 set_req(--ins_idx, st1);
3754 else
3755 ins_req(ins_idx, st1);
3756 }
3757 }
3758
3759 if (PrintCompilation && WizardMode)
3760 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
3761 old_subword, old_long, new_int, new_long);
3762 if (C->log() != NULL)
3763 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
3764 old_subword, old_long, new_int, new_long);
3765
3766 // Clean up any remaining occurrences of zmem:
3767 remove_extra_zeroes();
3768 }
3769
3770 // Explore forward from in(start) to find the first fully initialized
3771 // word, and return its offset. Skip groups of subword stores which
3772 // together initialize full words. If in(start) is itself part of a
3773 // fully initialized word, return the offset of in(start). If there
3774 // are no following full-word stores, or if something is fishy, return
3775 // a negative value.
3776 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
3777 int int_map = 0;
3778 intptr_t int_map_off = 0;
3779 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
3780
3781 for (uint i = start, limit = req(); i < limit; i++) {
3782 Node* st = in(i);
3783
3784 intptr_t st_off = get_store_offset(st, phase);
3785 if (st_off < 0) break; // return conservative answer
3786
3787 int st_size = st->as_Store()->memory_size();
3788 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
3789 return st_off; // we found a complete word init
3790 }
3791
3792 // update the map:
3793
3794 intptr_t this_int_off = align_size_down(st_off, BytesPerInt);
3795 if (this_int_off != int_map_off) {
3796 // reset the map:
3797 int_map = 0;
3798 int_map_off = this_int_off;
3799 }
3800
3801 int subword_off = st_off - this_int_off;
3802 int_map |= right_n_bits(st_size) << subword_off;
3803 if ((int_map & FULL_MAP) == FULL_MAP) {
3804 return this_int_off; // we found a complete word init
3805 }
3806
3807 // Did this store hit or cross the word boundary?
3808 intptr_t next_int_off = align_size_down(st_off + st_size, BytesPerInt);
3809 if (next_int_off == this_int_off + BytesPerInt) {
3810 // We passed the current int, without fully initializing it.
3811 int_map_off = next_int_off;
3812 int_map >>= BytesPerInt;
3813 } else if (next_int_off > this_int_off + BytesPerInt) {
3814 // We passed the current and next int.
3815 return this_int_off + BytesPerInt;
3816 }
3817 }
3818
3819 return -1;
3820 }
3821
3822
3823 // Called when the associated AllocateNode is expanded into CFG.
3824 // At this point, we may perform additional optimizations.
3825 // Linearize the stores by ascending offset, to make memory
3826 // activity as coherent as possible.
3827 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
3828 intptr_t header_size,
3829 Node* size_in_bytes,
3830 PhaseGVN* phase) {
3831 assert(!is_complete(), "not already complete");
3832 assert(stores_are_sane(phase), "");
3833 assert(allocation() != NULL, "must be present");
3834
3835 remove_extra_zeroes();
3836
3837 if (ReduceFieldZeroing || ReduceBulkZeroing)
3838 // reduce instruction count for common initialization patterns
3839 coalesce_subword_stores(header_size, size_in_bytes, phase);
3840
3841 Node* zmem = zero_memory(); // initially zero memory state
3842 Node* inits = zmem; // accumulating a linearized chain of inits
3843 #ifdef ASSERT
3844 intptr_t first_offset = allocation()->minimum_header_size();
3845 intptr_t last_init_off = first_offset; // previous init offset
3846 intptr_t last_init_end = first_offset; // previous init offset+size
3847 intptr_t last_tile_end = first_offset; // previous tile offset+size
3848 #endif
3849 intptr_t zeroes_done = header_size;
3850
3851 bool do_zeroing = true; // we might give up if inits are very sparse
3852 int big_init_gaps = 0; // how many large gaps have we seen?
3853
3854 if (ZeroTLAB) do_zeroing = false;
3855 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
3856
3857 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3858 Node* st = in(i);
3859 intptr_t st_off = get_store_offset(st, phase);
3860 if (st_off < 0)
3861 break; // unknown junk in the inits
3862 if (st->in(MemNode::Memory) != zmem)
3863 break; // complicated store chains somehow in list
3864
3865 int st_size = st->as_Store()->memory_size();
3866 intptr_t next_init_off = st_off + st_size;
3867
3868 if (do_zeroing && zeroes_done < next_init_off) {
3869 // See if this store needs a zero before it or under it.
3870 intptr_t zeroes_needed = st_off;
3871
3872 if (st_size < BytesPerInt) {
3873 // Look for subword stores which only partially initialize words.
3874 // If we find some, we must lay down some word-level zeroes first,
3875 // underneath the subword stores.
3876 //
3877 // Examples:
3878 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
3879 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
3880 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
3881 //
3882 // Note: coalesce_subword_stores may have already done this,
3883 // if it was prompted by constant non-zero subword initializers.
3884 // But this case can still arise with non-constant stores.
3885
3886 intptr_t next_full_store = find_next_fullword_store(i, phase);
3887
3888 // In the examples above:
3889 // in(i) p q r s x y z
3890 // st_off 12 13 14 15 12 13 14
3891 // st_size 1 1 1 1 1 1 1
3892 // next_full_s. 12 16 16 16 16 16 16
3893 // z's_done 12 16 16 16 12 16 12
3894 // z's_needed 12 16 16 16 16 16 16
3895 // zsize 0 0 0 0 4 0 4
3896 if (next_full_store < 0) {
3897 // Conservative tack: Zero to end of current word.
3898 zeroes_needed = align_size_up(zeroes_needed, BytesPerInt);
3899 } else {
3900 // Zero to beginning of next fully initialized word.
3901 // Or, don't zero at all, if we are already in that word.
3902 assert(next_full_store >= zeroes_needed, "must go forward");
3903 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
3904 zeroes_needed = next_full_store;
3905 }
3906 }
3907
3908 if (zeroes_needed > zeroes_done) {
3909 intptr_t zsize = zeroes_needed - zeroes_done;
3910 // Do some incremental zeroing on rawmem, in parallel with inits.
3911 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3912 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3913 zeroes_done, zeroes_needed,
3914 phase);
3915 zeroes_done = zeroes_needed;
3916 if (zsize > Matcher::init_array_short_size && ++big_init_gaps > 2)
3917 do_zeroing = false; // leave the hole, next time
3918 }
3919 }
3920
3921 // Collect the store and move on:
3922 st->set_req(MemNode::Memory, inits);
3923 inits = st; // put it on the linearized chain
3924 set_req(i, zmem); // unhook from previous position
3925
3926 if (zeroes_done == st_off)
3927 zeroes_done = next_init_off;
3928
3929 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
3930
3931 #ifdef ASSERT
3932 // Various order invariants. Weaker than stores_are_sane because
3933 // a large constant tile can be filled in by smaller non-constant stores.
3934 assert(st_off >= last_init_off, "inits do not reverse");
3935 last_init_off = st_off;
3936 const Type* val = NULL;
3937 if (st_size >= BytesPerInt &&
3938 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
3939 (int)val->basic_type() < (int)T_OBJECT) {
3940 assert(st_off >= last_tile_end, "tiles do not overlap");
3941 assert(st_off >= last_init_end, "tiles do not overwrite inits");
3942 last_tile_end = MAX2(last_tile_end, next_init_off);
3943 } else {
3944 intptr_t st_tile_end = align_size_up(next_init_off, BytesPerLong);
3945 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
3946 assert(st_off >= last_init_end, "inits do not overlap");
3947 last_init_end = next_init_off; // it's a non-tile
3948 }
3949 #endif //ASSERT
3950 }
3951
3952 remove_extra_zeroes(); // clear out all the zmems left over
3953 add_req(inits);
3954
3955 if (!ZeroTLAB) {
3956 // If anything remains to be zeroed, zero it all now.
3957 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3958 // if it is the last unused 4 bytes of an instance, forget about it
3959 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
3960 if (zeroes_done + BytesPerLong >= size_limit) {
3961 assert(allocation() != NULL, "");
3962 if (allocation()->Opcode() == Op_Allocate) {
3963 Node* klass_node = allocation()->in(AllocateNode::KlassNode);
3964 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass();
3965 if (zeroes_done == k->layout_helper())
3966 zeroes_done = size_limit;
3967 }
3968 }
3969 if (zeroes_done < size_limit) {
3970 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3971 zeroes_done, size_in_bytes, phase);
3972 }
3973 }
3974
3975 set_complete(phase);
3976 return rawmem;
3977 }
3978
3979
3980 #ifdef ASSERT
3981 bool InitializeNode::stores_are_sane(PhaseTransform* phase) {
3982 if (is_complete())
3983 return true; // stores could be anything at this point
3984 assert(allocation() != NULL, "must be present");
3985 intptr_t last_off = allocation()->minimum_header_size();
3986 for (uint i = InitializeNode::RawStores; i < req(); i++) {
3987 Node* st = in(i);
3988 intptr_t st_off = get_store_offset(st, phase);
3989 if (st_off < 0) continue; // ignore dead garbage
3990 if (last_off > st_off) {
3991 tty->print_cr("*** bad store offset at %d: " INTX_FORMAT " > " INTX_FORMAT, i, last_off, st_off);
3992 this->dump(2);
3993 assert(false, "ascending store offsets");
3994 return false;
3995 }
3996 last_off = st_off + st->as_Store()->memory_size();
3997 }
3998 return true;
3999 }
4000 #endif //ASSERT
4001
4002
4003
4004
4005 //============================MergeMemNode=====================================
4006 //
4007 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
4008 // contributing store or call operations. Each contributor provides the memory
4009 // state for a particular "alias type" (see Compile::alias_type). For example,
4010 // if a MergeMem has an input X for alias category #6, then any memory reference
4011 // to alias category #6 may use X as its memory state input, as an exact equivalent
4012 // to using the MergeMem as a whole.
4013 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
4014 //
4015 // (Here, the <N> notation gives the index of the relevant adr_type.)
4016 //
4017 // In one special case (and more cases in the future), alias categories overlap.
4018 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
4019 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
4020 // it is exactly equivalent to that state W:
4021 // MergeMem(<Bot>: W) <==> W
4022 //
4023 // Usually, the merge has more than one input. In that case, where inputs
4024 // overlap (i.e., one is Bot), the narrower alias type determines the memory
4025 // state for that type, and the wider alias type (Bot) fills in everywhere else:
4026 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
4027 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
4028 //
4029 // A merge can take a "wide" memory state as one of its narrow inputs.
4030 // This simply means that the merge observes out only the relevant parts of
4031 // the wide input. That is, wide memory states arriving at narrow merge inputs
4032 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
4033 //
4034 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
4035 // and that memory slices "leak through":
4036 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
4037 //
4038 // But, in such a cascade, repeated memory slices can "block the leak":
4039 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
4040 //
4041 // In the last example, Y is not part of the combined memory state of the
4042 // outermost MergeMem. The system must, of course, prevent unschedulable
4043 // memory states from arising, so you can be sure that the state Y is somehow
4044 // a precursor to state Y'.
4045 //
4046 //
4047 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
4048 // of each MergeMemNode array are exactly the numerical alias indexes, including
4049 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
4050 // Compile::alias_type (and kin) produce and manage these indexes.
4051 //
4052 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
4053 // (Note that this provides quick access to the top node inside MergeMem methods,
4054 // without the need to reach out via TLS to Compile::current.)
4055 //
4056 // As a consequence of what was just described, a MergeMem that represents a full
4057 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
4058 // containing all alias categories.
4059 //
4060 // MergeMem nodes never (?) have control inputs, so in(0) is NULL.
4061 //
4062 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
4063 // a memory state for the alias type <N>, or else the top node, meaning that
4064 // there is no particular input for that alias type. Note that the length of
4065 // a MergeMem is variable, and may be extended at any time to accommodate new
4066 // memory states at larger alias indexes. When merges grow, they are of course
4067 // filled with "top" in the unused in() positions.
4068 //
4069 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
4070 // (Top was chosen because it works smoothly with passes like GCM.)
4071 //
4072 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
4073 // the type of random VM bits like TLS references.) Since it is always the
4074 // first non-Bot memory slice, some low-level loops use it to initialize an
4075 // index variable: for (i = AliasIdxRaw; i < req(); i++).
4076 //
4077 //
4078 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
4079 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
4080 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
4081 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
4082 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
4083 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
4084 //
4085 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
4086 // really that different from the other memory inputs. An abbreviation called
4087 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
4088 //
4089 //
4090 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
4091 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
4092 // that "emerges though" the base memory will be marked as excluding the alias types
4093 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
4094 //
4095 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
4096 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
4097 //
4098 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
4099 // (It is currently unimplemented.) As you can see, the resulting merge is
4100 // actually a disjoint union of memory states, rather than an overlay.
4101 //
4102
4103 //------------------------------MergeMemNode-----------------------------------
4104 Node* MergeMemNode::make_empty_memory() {
4105 Node* empty_memory = (Node*) Compile::current()->top();
4106 assert(empty_memory->is_top(), "correct sentinel identity");
4107 return empty_memory;
4108 }
4109
4110 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
4111 init_class_id(Class_MergeMem);
4112 // all inputs are nullified in Node::Node(int)
4113 // set_input(0, NULL); // no control input
4114
4115 // Initialize the edges uniformly to top, for starters.
4116 Node* empty_mem = make_empty_memory();
4117 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
4118 init_req(i,empty_mem);
4119 }
4120 assert(empty_memory() == empty_mem, "");
4121
4122 if( new_base != NULL && new_base->is_MergeMem() ) {
4123 MergeMemNode* mdef = new_base->as_MergeMem();
4124 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
4125 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
4126 mms.set_memory(mms.memory2());
4127 }
4128 assert(base_memory() == mdef->base_memory(), "");
4129 } else {
4130 set_base_memory(new_base);
4131 }
4132 }
4133
4134 // Make a new, untransformed MergeMem with the same base as 'mem'.
4135 // If mem is itself a MergeMem, populate the result with the same edges.
4136 MergeMemNode* MergeMemNode::make(Node* mem) {
4137 return new MergeMemNode(mem);
4138 }
4139
4140 //------------------------------cmp--------------------------------------------
4141 uint MergeMemNode::hash() const { return NO_HASH; }
4142 uint MergeMemNode::cmp( const Node &n ) const {
4143 return (&n == this); // Always fail except on self
4144 }
4145
4146 //------------------------------Identity---------------------------------------
4147 Node* MergeMemNode::Identity(PhaseTransform *phase) {
4148 // Identity if this merge point does not record any interesting memory
4149 // disambiguations.
4150 Node* base_mem = base_memory();
4151 Node* empty_mem = empty_memory();
4152 if (base_mem != empty_mem) { // Memory path is not dead?
4153 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4154 Node* mem = in(i);
4155 if (mem != empty_mem && mem != base_mem) {
4156 return this; // Many memory splits; no change
4157 }
4158 }
4159 }
4160 return base_mem; // No memory splits; ID on the one true input
4161 }
4162
4163 //------------------------------Ideal------------------------------------------
4164 // This method is invoked recursively on chains of MergeMem nodes
4165 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4166 // Remove chain'd MergeMems
4167 //
4168 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
4169 // relative to the "in(Bot)". Since we are patching both at the same time,
4170 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
4171 // but rewrite each "in(i)" relative to the new "in(Bot)".
4172 Node *progress = NULL;
4173
4174
4175 Node* old_base = base_memory();
4176 Node* empty_mem = empty_memory();
4177 if (old_base == empty_mem)
4178 return NULL; // Dead memory path.
4179
4180 MergeMemNode* old_mbase;
4181 if (old_base != NULL && old_base->is_MergeMem())
4182 old_mbase = old_base->as_MergeMem();
4183 else
4184 old_mbase = NULL;
4185 Node* new_base = old_base;
4186
4187 // simplify stacked MergeMems in base memory
4188 if (old_mbase) new_base = old_mbase->base_memory();
4189
4190 // the base memory might contribute new slices beyond my req()
4191 if (old_mbase) grow_to_match(old_mbase);
4192
4193 // Look carefully at the base node if it is a phi.
4194 PhiNode* phi_base;
4195 if (new_base != NULL && new_base->is_Phi())
4196 phi_base = new_base->as_Phi();
4197 else
4198 phi_base = NULL;
4199
4200 Node* phi_reg = NULL;
4201 uint phi_len = (uint)-1;
4202 if (phi_base != NULL && !phi_base->is_copy()) {
4203 // do not examine phi if degraded to a copy
4204 phi_reg = phi_base->region();
4205 phi_len = phi_base->req();
4206 // see if the phi is unfinished
4207 for (uint i = 1; i < phi_len; i++) {
4208 if (phi_base->in(i) == NULL) {
4209 // incomplete phi; do not look at it yet!
4210 phi_reg = NULL;
4211 phi_len = (uint)-1;
4212 break;
4213 }
4214 }
4215 }
4216
4217 // Note: We do not call verify_sparse on entry, because inputs
4218 // can normalize to the base_memory via subsume_node or similar
4219 // mechanisms. This method repairs that damage.
4220
4221 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
4222
4223 // Look at each slice.
4224 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4225 Node* old_in = in(i);
4226 // calculate the old memory value
4227 Node* old_mem = old_in;
4228 if (old_mem == empty_mem) old_mem = old_base;
4229 assert(old_mem == memory_at(i), "");
4230
4231 // maybe update (reslice) the old memory value
4232
4233 // simplify stacked MergeMems
4234 Node* new_mem = old_mem;
4235 MergeMemNode* old_mmem;
4236 if (old_mem != NULL && old_mem->is_MergeMem())
4237 old_mmem = old_mem->as_MergeMem();
4238 else
4239 old_mmem = NULL;
4240 if (old_mmem == this) {
4241 // This can happen if loops break up and safepoints disappear.
4242 // A merge of BotPtr (default) with a RawPtr memory derived from a
4243 // safepoint can be rewritten to a merge of the same BotPtr with
4244 // the BotPtr phi coming into the loop. If that phi disappears
4245 // also, we can end up with a self-loop of the mergemem.
4246 // In general, if loops degenerate and memory effects disappear,
4247 // a mergemem can be left looking at itself. This simply means
4248 // that the mergemem's default should be used, since there is
4249 // no longer any apparent effect on this slice.
4250 // Note: If a memory slice is a MergeMem cycle, it is unreachable
4251 // from start. Update the input to TOP.
4252 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
4253 }
4254 else if (old_mmem != NULL) {
4255 new_mem = old_mmem->memory_at(i);
4256 }
4257 // else preceding memory was not a MergeMem
4258
4259 // replace equivalent phis (unfortunately, they do not GVN together)
4260 if (new_mem != NULL && new_mem != new_base &&
4261 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) {
4262 if (new_mem->is_Phi()) {
4263 PhiNode* phi_mem = new_mem->as_Phi();
4264 for (uint i = 1; i < phi_len; i++) {
4265 if (phi_base->in(i) != phi_mem->in(i)) {
4266 phi_mem = NULL;
4267 break;
4268 }
4269 }
4270 if (phi_mem != NULL) {
4271 // equivalent phi nodes; revert to the def
4272 new_mem = new_base;
4273 }
4274 }
4275 }
4276
4277 // maybe store down a new value
4278 Node* new_in = new_mem;
4279 if (new_in == new_base) new_in = empty_mem;
4280
4281 if (new_in != old_in) {
4282 // Warning: Do not combine this "if" with the previous "if"
4283 // A memory slice might have be be rewritten even if it is semantically
4284 // unchanged, if the base_memory value has changed.
4285 set_req(i, new_in);
4286 progress = this; // Report progress
4287 }
4288 }
4289
4290 if (new_base != old_base) {
4291 set_req(Compile::AliasIdxBot, new_base);
4292 // Don't use set_base_memory(new_base), because we need to update du.
4293 assert(base_memory() == new_base, "");
4294 progress = this;
4295 }
4296
4297 if( base_memory() == this ) {
4298 // a self cycle indicates this memory path is dead
4299 set_req(Compile::AliasIdxBot, empty_mem);
4300 }
4301
4302 // Resolve external cycles by calling Ideal on a MergeMem base_memory
4303 // Recursion must occur after the self cycle check above
4304 if( base_memory()->is_MergeMem() ) {
4305 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
4306 Node *m = phase->transform(new_mbase); // Rollup any cycles
4307 if( m != NULL && (m->is_top() ||
4308 m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem) ) {
4309 // propagate rollup of dead cycle to self
4310 set_req(Compile::AliasIdxBot, empty_mem);
4311 }
4312 }
4313
4314 if( base_memory() == empty_mem ) {
4315 progress = this;
4316 // Cut inputs during Parse phase only.
4317 // During Optimize phase a dead MergeMem node will be subsumed by Top.
4318 if( !can_reshape ) {
4319 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4320 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
4321 }
4322 }
4323 }
4324
4325 if( !progress && base_memory()->is_Phi() && can_reshape ) {
4326 // Check if PhiNode::Ideal's "Split phis through memory merges"
4327 // transform should be attempted. Look for this->phi->this cycle.
4328 uint merge_width = req();
4329 if (merge_width > Compile::AliasIdxRaw) {
4330 PhiNode* phi = base_memory()->as_Phi();
4331 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
4332 if (phi->in(i) == this) {
4333 phase->is_IterGVN()->_worklist.push(phi);
4334 break;
4335 }
4336 }
4337 }
4338 }
4339
4340 assert(progress || verify_sparse(), "please, no dups of base");
4341 return progress;
4342 }
4343
4344 //-------------------------set_base_memory-------------------------------------
4345 void MergeMemNode::set_base_memory(Node *new_base) {
4346 Node* empty_mem = empty_memory();
4347 set_req(Compile::AliasIdxBot, new_base);
4348 assert(memory_at(req()) == new_base, "must set default memory");
4349 // Clear out other occurrences of new_base:
4350 if (new_base != empty_mem) {
4351 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4352 if (in(i) == new_base) set_req(i, empty_mem);
4353 }
4354 }
4355 }
4356
4357 //------------------------------out_RegMask------------------------------------
4358 const RegMask &MergeMemNode::out_RegMask() const {
4359 return RegMask::Empty;
4360 }
4361
4362 //------------------------------dump_spec--------------------------------------
4363 #ifndef PRODUCT
4364 void MergeMemNode::dump_spec(outputStream *st) const {
4365 st->print(" {");
4366 Node* base_mem = base_memory();
4367 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
4368 Node* mem = (in(i) != NULL) ? memory_at(i) : base_mem;
4369 if (mem == base_mem) { st->print(" -"); continue; }
4370 st->print( " N%d:", mem->_idx );
4371 Compile::current()->get_adr_type(i)->dump_on(st);
4372 }
4373 st->print(" }");
4374 }
4375 #endif // !PRODUCT
4376
4377
4378 #ifdef ASSERT
4379 static bool might_be_same(Node* a, Node* b) {
4380 if (a == b) return true;
4381 if (!(a->is_Phi() || b->is_Phi())) return false;
4382 // phis shift around during optimization
4383 return true; // pretty stupid...
4384 }
4385
4386 // verify a narrow slice (either incoming or outgoing)
4387 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
4388 if (!VerifyAliases) return; // don't bother to verify unless requested
4389 if (is_error_reported()) return; // muzzle asserts when debugging an error
4390 if (Node::in_dump()) return; // muzzle asserts when printing
4391 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
4392 assert(n != NULL, "");
4393 // Elide intervening MergeMem's
4394 while (n->is_MergeMem()) {
4395 n = n->as_MergeMem()->memory_at(alias_idx);
4396 }
4397 Compile* C = Compile::current();
4398 const TypePtr* n_adr_type = n->adr_type();
4399 if (n == m->empty_memory()) {
4400 // Implicit copy of base_memory()
4401 } else if (n_adr_type != TypePtr::BOTTOM) {
4402 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type");
4403 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
4404 } else {
4405 // A few places like make_runtime_call "know" that VM calls are narrow,
4406 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
4407 bool expected_wide_mem = false;
4408 if (n == m->base_memory()) {
4409 expected_wide_mem = true;
4410 } else if (alias_idx == Compile::AliasIdxRaw ||
4411 n == m->memory_at(Compile::AliasIdxRaw)) {
4412 expected_wide_mem = true;
4413 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
4414 // memory can "leak through" calls on channels that
4415 // are write-once. Allow this also.
4416 expected_wide_mem = true;
4417 }
4418 assert(expected_wide_mem, "expected narrow slice replacement");
4419 }
4420 }
4421 #else // !ASSERT
4422 #define verify_memory_slice(m,i,n) (void)(0) // PRODUCT version is no-op
4423 #endif
4424
4425
4426 //-----------------------------memory_at---------------------------------------
4427 Node* MergeMemNode::memory_at(uint alias_idx) const {
4428 assert(alias_idx >= Compile::AliasIdxRaw ||
4429 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0,
4430 "must avoid base_memory and AliasIdxTop");
4431
4432 // Otherwise, it is a narrow slice.
4433 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
4434 Compile *C = Compile::current();
4435 if (is_empty_memory(n)) {
4436 // the array is sparse; empty slots are the "top" node
4437 n = base_memory();
4438 assert(Node::in_dump()
4439 || n == NULL || n->bottom_type() == Type::TOP
4440 || n->adr_type() == NULL // address is TOP
4441 || n->adr_type() == TypePtr::BOTTOM
4442 || n->adr_type() == TypeRawPtr::BOTTOM
4443 || Compile::current()->AliasLevel() == 0,
4444 "must be a wide memory");
4445 // AliasLevel == 0 if we are organizing the memory states manually.
4446 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
4447 } else {
4448 // make sure the stored slice is sane
4449 #ifdef ASSERT
4450 if (is_error_reported() || Node::in_dump()) {
4451 } else if (might_be_same(n, base_memory())) {
4452 // Give it a pass: It is a mostly harmless repetition of the base.
4453 // This can arise normally from node subsumption during optimization.
4454 } else {
4455 verify_memory_slice(this, alias_idx, n);
4456 }
4457 #endif
4458 }
4459 return n;
4460 }
4461
4462 //---------------------------set_memory_at-------------------------------------
4463 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
4464 verify_memory_slice(this, alias_idx, n);
4465 Node* empty_mem = empty_memory();
4466 if (n == base_memory()) n = empty_mem; // collapse default
4467 uint need_req = alias_idx+1;
4468 if (req() < need_req) {
4469 if (n == empty_mem) return; // already the default, so do not grow me
4470 // grow the sparse array
4471 do {
4472 add_req(empty_mem);
4473 } while (req() < need_req);
4474 }
4475 set_req( alias_idx, n );
4476 }
4477
4478
4479
4480 //--------------------------iteration_setup------------------------------------
4481 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
4482 if (other != NULL) {
4483 grow_to_match(other);
4484 // invariant: the finite support of mm2 is within mm->req()
4485 #ifdef ASSERT
4486 for (uint i = req(); i < other->req(); i++) {
4487 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
4488 }
4489 #endif
4490 }
4491 // Replace spurious copies of base_memory by top.
4492 Node* base_mem = base_memory();
4493 if (base_mem != NULL && !base_mem->is_top()) {
4494 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
4495 if (in(i) == base_mem)
4496 set_req(i, empty_memory());
4497 }
4498 }
4499 }
4500
4501 //---------------------------grow_to_match-------------------------------------
4502 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
4503 Node* empty_mem = empty_memory();
4504 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
4505 // look for the finite support of the other memory
4506 for (uint i = other->req(); --i >= req(); ) {
4507 if (other->in(i) != empty_mem) {
4508 uint new_len = i+1;
4509 while (req() < new_len) add_req(empty_mem);
4510 break;
4511 }
4512 }
4513 }
4514
4515 //---------------------------verify_sparse-------------------------------------
4516 #ifndef PRODUCT
4517 bool MergeMemNode::verify_sparse() const {
4518 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
4519 Node* base_mem = base_memory();
4520 // The following can happen in degenerate cases, since empty==top.
4521 if (is_empty_memory(base_mem)) return true;
4522 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4523 assert(in(i) != NULL, "sane slice");
4524 if (in(i) == base_mem) return false; // should have been the sentinel value!
4525 }
4526 return true;
4527 }
4528
4529 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
4530 Node* n;
4531 n = mm->in(idx);
4532 if (mem == n) return true; // might be empty_memory()
4533 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
4534 if (mem == n) return true;
4535 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) {
4536 if (mem == n) return true;
4537 if (n == NULL) break;
4538 }
4539 return false;
4540 }
4541 #endif // !PRODUCT