Wed, 18 Sep 2013 14:34:56 -0700
8024342: PPC64 (part 111): Support for C calling conventions that require 64-bit ints.
Summary: Some platforms, as ppc and s390x/zArch require that 32-bit ints are passed as 64-bit values to C functions. This change adds support to adapt the signature and to issue proper casts to c2-compiled stubs. The functions are used in generate_native_wrapper(). Adapt signature used by the compiler as in PhaseIdealLoop::intrinsify_fill().
Reviewed-by: kvn
1 /*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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25 #include "precompiled.hpp"
26 #include "classfile/systemDictionary.hpp"
27 #include "compiler/compileLog.hpp"
28 #include "memory/allocation.inline.hpp"
29 #include "oops/objArrayKlass.hpp"
30 #include "opto/addnode.hpp"
31 #include "opto/cfgnode.hpp"
32 #include "opto/compile.hpp"
33 #include "opto/connode.hpp"
34 #include "opto/loopnode.hpp"
35 #include "opto/machnode.hpp"
36 #include "opto/matcher.hpp"
37 #include "opto/memnode.hpp"
38 #include "opto/mulnode.hpp"
39 #include "opto/phaseX.hpp"
40 #include "opto/regmask.hpp"
42 // Portions of code courtesy of Clifford Click
44 // Optimization - Graph Style
46 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st);
48 //=============================================================================
49 uint MemNode::size_of() const { return sizeof(*this); }
51 const TypePtr *MemNode::adr_type() const {
52 Node* adr = in(Address);
53 const TypePtr* cross_check = NULL;
54 DEBUG_ONLY(cross_check = _adr_type);
55 return calculate_adr_type(adr->bottom_type(), cross_check);
56 }
58 #ifndef PRODUCT
59 void MemNode::dump_spec(outputStream *st) const {
60 if (in(Address) == NULL) return; // node is dead
61 #ifndef ASSERT
62 // fake the missing field
63 const TypePtr* _adr_type = NULL;
64 if (in(Address) != NULL)
65 _adr_type = in(Address)->bottom_type()->isa_ptr();
66 #endif
67 dump_adr_type(this, _adr_type, st);
69 Compile* C = Compile::current();
70 if( C->alias_type(_adr_type)->is_volatile() )
71 st->print(" Volatile!");
72 }
74 void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) {
75 st->print(" @");
76 if (adr_type == NULL) {
77 st->print("NULL");
78 } else {
79 adr_type->dump_on(st);
80 Compile* C = Compile::current();
81 Compile::AliasType* atp = NULL;
82 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type);
83 if (atp == NULL)
84 st->print(", idx=?\?;");
85 else if (atp->index() == Compile::AliasIdxBot)
86 st->print(", idx=Bot;");
87 else if (atp->index() == Compile::AliasIdxTop)
88 st->print(", idx=Top;");
89 else if (atp->index() == Compile::AliasIdxRaw)
90 st->print(", idx=Raw;");
91 else {
92 ciField* field = atp->field();
93 if (field) {
94 st->print(", name=");
95 field->print_name_on(st);
96 }
97 st->print(", idx=%d;", atp->index());
98 }
99 }
100 }
102 extern void print_alias_types();
104 #endif
106 Node *MemNode::optimize_simple_memory_chain(Node *mchain, const TypeOopPtr *t_oop, Node *load, PhaseGVN *phase) {
107 assert((t_oop != NULL), "sanity");
108 bool is_instance = t_oop->is_known_instance_field();
109 bool is_boxed_value_load = t_oop->is_ptr_to_boxed_value() &&
110 (load != NULL) && load->is_Load() &&
111 (phase->is_IterGVN() != NULL);
112 if (!(is_instance || is_boxed_value_load))
113 return mchain; // don't try to optimize non-instance types
114 uint instance_id = t_oop->instance_id();
115 Node *start_mem = phase->C->start()->proj_out(TypeFunc::Memory);
116 Node *prev = NULL;
117 Node *result = mchain;
118 while (prev != result) {
119 prev = result;
120 if (result == start_mem)
121 break; // hit one of our sentinels
122 // skip over a call which does not affect this memory slice
123 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {
124 Node *proj_in = result->in(0);
125 if (proj_in->is_Allocate() && proj_in->_idx == instance_id) {
126 break; // hit one of our sentinels
127 } else if (proj_in->is_Call()) {
128 CallNode *call = proj_in->as_Call();
129 if (!call->may_modify(t_oop, phase)) { // returns false for instances
130 result = call->in(TypeFunc::Memory);
131 }
132 } else if (proj_in->is_Initialize()) {
133 AllocateNode* alloc = proj_in->as_Initialize()->allocation();
134 // Stop if this is the initialization for the object instance which
135 // which contains this memory slice, otherwise skip over it.
136 if ((alloc == NULL) || (alloc->_idx == instance_id)) {
137 break;
138 }
139 if (is_instance) {
140 result = proj_in->in(TypeFunc::Memory);
141 } else if (is_boxed_value_load) {
142 Node* klass = alloc->in(AllocateNode::KlassNode);
143 const TypeKlassPtr* tklass = phase->type(klass)->is_klassptr();
144 if (tklass->klass_is_exact() && !tklass->klass()->equals(t_oop->klass())) {
145 result = proj_in->in(TypeFunc::Memory); // not related allocation
146 }
147 }
148 } else if (proj_in->is_MemBar()) {
149 result = proj_in->in(TypeFunc::Memory);
150 } else {
151 assert(false, "unexpected projection");
152 }
153 } else if (result->is_ClearArray()) {
154 if (!is_instance || !ClearArrayNode::step_through(&result, instance_id, phase)) {
155 // Can not bypass initialization of the instance
156 // we are looking for.
157 break;
158 }
159 // Otherwise skip it (the call updated 'result' value).
160 } else if (result->is_MergeMem()) {
161 result = step_through_mergemem(phase, result->as_MergeMem(), t_oop, NULL, tty);
162 }
163 }
164 return result;
165 }
167 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, Node *load, PhaseGVN *phase) {
168 const TypeOopPtr* t_oop = t_adr->isa_oopptr();
169 if (t_oop == NULL)
170 return mchain; // don't try to optimize non-oop types
171 Node* result = optimize_simple_memory_chain(mchain, t_oop, load, phase);
172 bool is_instance = t_oop->is_known_instance_field();
173 PhaseIterGVN *igvn = phase->is_IterGVN();
174 if (is_instance && igvn != NULL && result->is_Phi()) {
175 PhiNode *mphi = result->as_Phi();
176 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
177 const TypePtr *t = mphi->adr_type();
178 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
179 t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
180 t->is_oopptr()->cast_to_exactness(true)
181 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
182 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop) {
183 // clone the Phi with our address type
184 result = mphi->split_out_instance(t_adr, igvn);
185 } else {
186 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain");
187 }
188 }
189 return result;
190 }
192 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) {
193 uint alias_idx = phase->C->get_alias_index(tp);
194 Node *mem = mmem;
195 #ifdef ASSERT
196 {
197 // Check that current type is consistent with the alias index used during graph construction
198 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
199 bool consistent = adr_check == NULL || adr_check->empty() ||
200 phase->C->must_alias(adr_check, alias_idx );
201 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
202 if( !consistent && adr_check != NULL && !adr_check->empty() &&
203 tp->isa_aryptr() && tp->offset() == Type::OffsetBot &&
204 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot &&
205 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() ||
206 adr_check->offset() == oopDesc::klass_offset_in_bytes() ||
207 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) {
208 // don't assert if it is dead code.
209 consistent = true;
210 }
211 if( !consistent ) {
212 st->print("alias_idx==%d, adr_check==", alias_idx);
213 if( adr_check == NULL ) {
214 st->print("NULL");
215 } else {
216 adr_check->dump();
217 }
218 st->cr();
219 print_alias_types();
220 assert(consistent, "adr_check must match alias idx");
221 }
222 }
223 #endif
224 // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally
225 // means an array I have not precisely typed yet. Do not do any
226 // alias stuff with it any time soon.
227 const TypeOopPtr *toop = tp->isa_oopptr();
228 if( tp->base() != Type::AnyPtr &&
229 !(toop &&
230 toop->klass() != NULL &&
231 toop->klass()->is_java_lang_Object() &&
232 toop->offset() == Type::OffsetBot) ) {
233 // compress paths and change unreachable cycles to TOP
234 // If not, we can update the input infinitely along a MergeMem cycle
235 // Equivalent code in PhiNode::Ideal
236 Node* m = phase->transform(mmem);
237 // If transformed to a MergeMem, get the desired slice
238 // Otherwise the returned node represents memory for every slice
239 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
240 // Update input if it is progress over what we have now
241 }
242 return mem;
243 }
245 //--------------------------Ideal_common---------------------------------------
246 // Look for degenerate control and memory inputs. Bypass MergeMem inputs.
247 // Unhook non-raw memories from complete (macro-expanded) initializations.
248 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
249 // If our control input is a dead region, kill all below the region
250 Node *ctl = in(MemNode::Control);
251 if (ctl && remove_dead_region(phase, can_reshape))
252 return this;
253 ctl = in(MemNode::Control);
254 // Don't bother trying to transform a dead node
255 if (ctl && ctl->is_top()) return NodeSentinel;
257 PhaseIterGVN *igvn = phase->is_IterGVN();
258 // Wait if control on the worklist.
259 if (ctl && can_reshape && igvn != NULL) {
260 Node* bol = NULL;
261 Node* cmp = NULL;
262 if (ctl->in(0)->is_If()) {
263 assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity");
264 bol = ctl->in(0)->in(1);
265 if (bol->is_Bool())
266 cmp = ctl->in(0)->in(1)->in(1);
267 }
268 if (igvn->_worklist.member(ctl) ||
269 (bol != NULL && igvn->_worklist.member(bol)) ||
270 (cmp != NULL && igvn->_worklist.member(cmp)) ) {
271 // This control path may be dead.
272 // Delay this memory node transformation until the control is processed.
273 phase->is_IterGVN()->_worklist.push(this);
274 return NodeSentinel; // caller will return NULL
275 }
276 }
277 // Ignore if memory is dead, or self-loop
278 Node *mem = in(MemNode::Memory);
279 if (phase->type( mem ) == Type::TOP) return NodeSentinel; // caller will return NULL
280 assert(mem != this, "dead loop in MemNode::Ideal");
282 if (can_reshape && igvn != NULL && igvn->_worklist.member(mem)) {
283 // This memory slice may be dead.
284 // Delay this mem node transformation until the memory is processed.
285 phase->is_IterGVN()->_worklist.push(this);
286 return NodeSentinel; // caller will return NULL
287 }
289 Node *address = in(MemNode::Address);
290 const Type *t_adr = phase->type(address);
291 if (t_adr == Type::TOP) return NodeSentinel; // caller will return NULL
293 if (can_reshape && igvn != NULL &&
294 (igvn->_worklist.member(address) ||
295 igvn->_worklist.size() > 0 && (t_adr != adr_type())) ) {
296 // The address's base and type may change when the address is processed.
297 // Delay this mem node transformation until the address is processed.
298 phase->is_IterGVN()->_worklist.push(this);
299 return NodeSentinel; // caller will return NULL
300 }
302 // Do NOT remove or optimize the next lines: ensure a new alias index
303 // is allocated for an oop pointer type before Escape Analysis.
304 // Note: C++ will not remove it since the call has side effect.
305 if (t_adr->isa_oopptr()) {
306 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr());
307 }
309 #ifdef ASSERT
310 Node* base = NULL;
311 if (address->is_AddP())
312 base = address->in(AddPNode::Base);
313 if (base != NULL && phase->type(base)->higher_equal(TypePtr::NULL_PTR) &&
314 !t_adr->isa_rawptr()) {
315 // Note: raw address has TOP base and top->higher_equal(TypePtr::NULL_PTR) is true.
316 Compile* C = phase->C;
317 tty->cr();
318 tty->print_cr("===== NULL+offs not RAW address =====");
319 if (C->is_dead_node(this->_idx)) tty->print_cr("'this' is dead");
320 if ((ctl != NULL) && C->is_dead_node(ctl->_idx)) tty->print_cr("'ctl' is dead");
321 if (C->is_dead_node(mem->_idx)) tty->print_cr("'mem' is dead");
322 if (C->is_dead_node(address->_idx)) tty->print_cr("'address' is dead");
323 if (C->is_dead_node(base->_idx)) tty->print_cr("'base' is dead");
324 tty->cr();
325 base->dump(1);
326 tty->cr();
327 this->dump(2);
328 tty->print("this->adr_type(): "); adr_type()->dump(); tty->cr();
329 tty->print("phase->type(address): "); t_adr->dump(); tty->cr();
330 tty->print("phase->type(base): "); phase->type(address)->dump(); tty->cr();
331 tty->cr();
332 }
333 assert(base == NULL || t_adr->isa_rawptr() ||
334 !phase->type(base)->higher_equal(TypePtr::NULL_PTR), "NULL+offs not RAW address?");
335 #endif
337 // Avoid independent memory operations
338 Node* old_mem = mem;
340 // The code which unhooks non-raw memories from complete (macro-expanded)
341 // initializations was removed. After macro-expansion all stores catched
342 // by Initialize node became raw stores and there is no information
343 // which memory slices they modify. So it is unsafe to move any memory
344 // operation above these stores. Also in most cases hooked non-raw memories
345 // were already unhooked by using information from detect_ptr_independence()
346 // and find_previous_store().
348 if (mem->is_MergeMem()) {
349 MergeMemNode* mmem = mem->as_MergeMem();
350 const TypePtr *tp = t_adr->is_ptr();
352 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
353 }
355 if (mem != old_mem) {
356 set_req(MemNode::Memory, mem);
357 if (can_reshape && old_mem->outcnt() == 0) {
358 igvn->_worklist.push(old_mem);
359 }
360 if (phase->type( mem ) == Type::TOP) return NodeSentinel;
361 return this;
362 }
364 // let the subclass continue analyzing...
365 return NULL;
366 }
368 // Helper function for proving some simple control dominations.
369 // Attempt to prove that all control inputs of 'dom' dominate 'sub'.
370 // Already assumes that 'dom' is available at 'sub', and that 'sub'
371 // is not a constant (dominated by the method's StartNode).
372 // Used by MemNode::find_previous_store to prove that the
373 // control input of a memory operation predates (dominates)
374 // an allocation it wants to look past.
375 bool MemNode::all_controls_dominate(Node* dom, Node* sub) {
376 if (dom == NULL || dom->is_top() || sub == NULL || sub->is_top())
377 return false; // Conservative answer for dead code
379 // Check 'dom'. Skip Proj and CatchProj nodes.
380 dom = dom->find_exact_control(dom);
381 if (dom == NULL || dom->is_top())
382 return false; // Conservative answer for dead code
384 if (dom == sub) {
385 // For the case when, for example, 'sub' is Initialize and the original
386 // 'dom' is Proj node of the 'sub'.
387 return false;
388 }
390 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub)
391 return true;
393 // 'dom' dominates 'sub' if its control edge and control edges
394 // of all its inputs dominate or equal to sub's control edge.
396 // Currently 'sub' is either Allocate, Initialize or Start nodes.
397 // Or Region for the check in LoadNode::Ideal();
398 // 'sub' should have sub->in(0) != NULL.
399 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() ||
400 sub->is_Region() || sub->is_Call(), "expecting only these nodes");
402 // Get control edge of 'sub'.
403 Node* orig_sub = sub;
404 sub = sub->find_exact_control(sub->in(0));
405 if (sub == NULL || sub->is_top())
406 return false; // Conservative answer for dead code
408 assert(sub->is_CFG(), "expecting control");
410 if (sub == dom)
411 return true;
413 if (sub->is_Start() || sub->is_Root())
414 return false;
416 {
417 // Check all control edges of 'dom'.
419 ResourceMark rm;
420 Arena* arena = Thread::current()->resource_area();
421 Node_List nlist(arena);
422 Unique_Node_List dom_list(arena);
424 dom_list.push(dom);
425 bool only_dominating_controls = false;
427 for (uint next = 0; next < dom_list.size(); next++) {
428 Node* n = dom_list.at(next);
429 if (n == orig_sub)
430 return false; // One of dom's inputs dominated by sub.
431 if (!n->is_CFG() && n->pinned()) {
432 // Check only own control edge for pinned non-control nodes.
433 n = n->find_exact_control(n->in(0));
434 if (n == NULL || n->is_top())
435 return false; // Conservative answer for dead code
436 assert(n->is_CFG(), "expecting control");
437 dom_list.push(n);
438 } else if (n->is_Con() || n->is_Start() || n->is_Root()) {
439 only_dominating_controls = true;
440 } else if (n->is_CFG()) {
441 if (n->dominates(sub, nlist))
442 only_dominating_controls = true;
443 else
444 return false;
445 } else {
446 // First, own control edge.
447 Node* m = n->find_exact_control(n->in(0));
448 if (m != NULL) {
449 if (m->is_top())
450 return false; // Conservative answer for dead code
451 dom_list.push(m);
452 }
453 // Now, the rest of edges.
454 uint cnt = n->req();
455 for (uint i = 1; i < cnt; i++) {
456 m = n->find_exact_control(n->in(i));
457 if (m == NULL || m->is_top())
458 continue;
459 dom_list.push(m);
460 }
461 }
462 }
463 return only_dominating_controls;
464 }
465 }
467 //---------------------detect_ptr_independence---------------------------------
468 // Used by MemNode::find_previous_store to prove that two base
469 // pointers are never equal.
470 // The pointers are accompanied by their associated allocations,
471 // if any, which have been previously discovered by the caller.
472 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
473 Node* p2, AllocateNode* a2,
474 PhaseTransform* phase) {
475 // Attempt to prove that these two pointers cannot be aliased.
476 // They may both manifestly be allocations, and they should differ.
477 // Or, if they are not both allocations, they can be distinct constants.
478 // Otherwise, one is an allocation and the other a pre-existing value.
479 if (a1 == NULL && a2 == NULL) { // neither an allocation
480 return (p1 != p2) && p1->is_Con() && p2->is_Con();
481 } else if (a1 != NULL && a2 != NULL) { // both allocations
482 return (a1 != a2);
483 } else if (a1 != NULL) { // one allocation a1
484 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.)
485 return all_controls_dominate(p2, a1);
486 } else { //(a2 != NULL) // one allocation a2
487 return all_controls_dominate(p1, a2);
488 }
489 return false;
490 }
493 // The logic for reordering loads and stores uses four steps:
494 // (a) Walk carefully past stores and initializations which we
495 // can prove are independent of this load.
496 // (b) Observe that the next memory state makes an exact match
497 // with self (load or store), and locate the relevant store.
498 // (c) Ensure that, if we were to wire self directly to the store,
499 // the optimizer would fold it up somehow.
500 // (d) Do the rewiring, and return, depending on some other part of
501 // the optimizer to fold up the load.
502 // This routine handles steps (a) and (b). Steps (c) and (d) are
503 // specific to loads and stores, so they are handled by the callers.
504 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.)
505 //
506 Node* MemNode::find_previous_store(PhaseTransform* phase) {
507 Node* ctrl = in(MemNode::Control);
508 Node* adr = in(MemNode::Address);
509 intptr_t offset = 0;
510 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
511 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase);
513 if (offset == Type::OffsetBot)
514 return NULL; // cannot unalias unless there are precise offsets
516 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr();
518 intptr_t size_in_bytes = memory_size();
520 Node* mem = in(MemNode::Memory); // start searching here...
522 int cnt = 50; // Cycle limiter
523 for (;;) { // While we can dance past unrelated stores...
524 if (--cnt < 0) break; // Caught in cycle or a complicated dance?
526 if (mem->is_Store()) {
527 Node* st_adr = mem->in(MemNode::Address);
528 intptr_t st_offset = 0;
529 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
530 if (st_base == NULL)
531 break; // inscrutable pointer
532 if (st_offset != offset && st_offset != Type::OffsetBot) {
533 const int MAX_STORE = BytesPerLong;
534 if (st_offset >= offset + size_in_bytes ||
535 st_offset <= offset - MAX_STORE ||
536 st_offset <= offset - mem->as_Store()->memory_size()) {
537 // Success: The offsets are provably independent.
538 // (You may ask, why not just test st_offset != offset and be done?
539 // The answer is that stores of different sizes can co-exist
540 // in the same sequence of RawMem effects. We sometimes initialize
541 // a whole 'tile' of array elements with a single jint or jlong.)
542 mem = mem->in(MemNode::Memory);
543 continue; // (a) advance through independent store memory
544 }
545 }
546 if (st_base != base &&
547 detect_ptr_independence(base, alloc,
548 st_base,
549 AllocateNode::Ideal_allocation(st_base, phase),
550 phase)) {
551 // Success: The bases are provably independent.
552 mem = mem->in(MemNode::Memory);
553 continue; // (a) advance through independent store memory
554 }
556 // (b) At this point, if the bases or offsets do not agree, we lose,
557 // since we have not managed to prove 'this' and 'mem' independent.
558 if (st_base == base && st_offset == offset) {
559 return mem; // let caller handle steps (c), (d)
560 }
562 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
563 InitializeNode* st_init = mem->in(0)->as_Initialize();
564 AllocateNode* st_alloc = st_init->allocation();
565 if (st_alloc == NULL)
566 break; // something degenerated
567 bool known_identical = false;
568 bool known_independent = false;
569 if (alloc == st_alloc)
570 known_identical = true;
571 else if (alloc != NULL)
572 known_independent = true;
573 else if (all_controls_dominate(this, st_alloc))
574 known_independent = true;
576 if (known_independent) {
577 // The bases are provably independent: Either they are
578 // manifestly distinct allocations, or else the control
579 // of this load dominates the store's allocation.
580 int alias_idx = phase->C->get_alias_index(adr_type());
581 if (alias_idx == Compile::AliasIdxRaw) {
582 mem = st_alloc->in(TypeFunc::Memory);
583 } else {
584 mem = st_init->memory(alias_idx);
585 }
586 continue; // (a) advance through independent store memory
587 }
589 // (b) at this point, if we are not looking at a store initializing
590 // the same allocation we are loading from, we lose.
591 if (known_identical) {
592 // From caller, can_see_stored_value will consult find_captured_store.
593 return mem; // let caller handle steps (c), (d)
594 }
596 } else if (addr_t != NULL && addr_t->is_known_instance_field()) {
597 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
598 if (mem->is_Proj() && mem->in(0)->is_Call()) {
599 CallNode *call = mem->in(0)->as_Call();
600 if (!call->may_modify(addr_t, phase)) {
601 mem = call->in(TypeFunc::Memory);
602 continue; // (a) advance through independent call memory
603 }
604 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) {
605 mem = mem->in(0)->in(TypeFunc::Memory);
606 continue; // (a) advance through independent MemBar memory
607 } else if (mem->is_ClearArray()) {
608 if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) {
609 // (the call updated 'mem' value)
610 continue; // (a) advance through independent allocation memory
611 } else {
612 // Can not bypass initialization of the instance
613 // we are looking for.
614 return mem;
615 }
616 } else if (mem->is_MergeMem()) {
617 int alias_idx = phase->C->get_alias_index(adr_type());
618 mem = mem->as_MergeMem()->memory_at(alias_idx);
619 continue; // (a) advance through independent MergeMem memory
620 }
621 }
623 // Unless there is an explicit 'continue', we must bail out here,
624 // because 'mem' is an inscrutable memory state (e.g., a call).
625 break;
626 }
628 return NULL; // bail out
629 }
631 //----------------------calculate_adr_type-------------------------------------
632 // Helper function. Notices when the given type of address hits top or bottom.
633 // Also, asserts a cross-check of the type against the expected address type.
634 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
635 if (t == Type::TOP) return NULL; // does not touch memory any more?
636 #ifdef PRODUCT
637 cross_check = NULL;
638 #else
639 if (!VerifyAliases || is_error_reported() || Node::in_dump()) cross_check = NULL;
640 #endif
641 const TypePtr* tp = t->isa_ptr();
642 if (tp == NULL) {
643 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
644 return TypePtr::BOTTOM; // touches lots of memory
645 } else {
646 #ifdef ASSERT
647 // %%%% [phh] We don't check the alias index if cross_check is
648 // TypeRawPtr::BOTTOM. Needs to be investigated.
649 if (cross_check != NULL &&
650 cross_check != TypePtr::BOTTOM &&
651 cross_check != TypeRawPtr::BOTTOM) {
652 // Recheck the alias index, to see if it has changed (due to a bug).
653 Compile* C = Compile::current();
654 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
655 "must stay in the original alias category");
656 // The type of the address must be contained in the adr_type,
657 // disregarding "null"-ness.
658 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
659 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
660 assert(cross_check->meet(tp_notnull) == cross_check,
661 "real address must not escape from expected memory type");
662 }
663 #endif
664 return tp;
665 }
666 }
668 //------------------------adr_phi_is_loop_invariant----------------------------
669 // A helper function for Ideal_DU_postCCP to check if a Phi in a counted
670 // loop is loop invariant. Make a quick traversal of Phi and associated
671 // CastPP nodes, looking to see if they are a closed group within the loop.
672 bool MemNode::adr_phi_is_loop_invariant(Node* adr_phi, Node* cast) {
673 // The idea is that the phi-nest must boil down to only CastPP nodes
674 // with the same data. This implies that any path into the loop already
675 // includes such a CastPP, and so the original cast, whatever its input,
676 // must be covered by an equivalent cast, with an earlier control input.
677 ResourceMark rm;
679 // The loop entry input of the phi should be the unique dominating
680 // node for every Phi/CastPP in the loop.
681 Unique_Node_List closure;
682 closure.push(adr_phi->in(LoopNode::EntryControl));
684 // Add the phi node and the cast to the worklist.
685 Unique_Node_List worklist;
686 worklist.push(adr_phi);
687 if( cast != NULL ){
688 if( !cast->is_ConstraintCast() ) return false;
689 worklist.push(cast);
690 }
692 // Begin recursive walk of phi nodes.
693 while( worklist.size() ){
694 // Take a node off the worklist
695 Node *n = worklist.pop();
696 if( !closure.member(n) ){
697 // Add it to the closure.
698 closure.push(n);
699 // Make a sanity check to ensure we don't waste too much time here.
700 if( closure.size() > 20) return false;
701 // This node is OK if:
702 // - it is a cast of an identical value
703 // - or it is a phi node (then we add its inputs to the worklist)
704 // Otherwise, the node is not OK, and we presume the cast is not invariant
705 if( n->is_ConstraintCast() ){
706 worklist.push(n->in(1));
707 } else if( n->is_Phi() ) {
708 for( uint i = 1; i < n->req(); i++ ) {
709 worklist.push(n->in(i));
710 }
711 } else {
712 return false;
713 }
714 }
715 }
717 // Quit when the worklist is empty, and we've found no offending nodes.
718 return true;
719 }
721 //------------------------------Ideal_DU_postCCP-------------------------------
722 // Find any cast-away of null-ness and keep its control. Null cast-aways are
723 // going away in this pass and we need to make this memory op depend on the
724 // gating null check.
725 Node *MemNode::Ideal_DU_postCCP( PhaseCCP *ccp ) {
726 return Ideal_common_DU_postCCP(ccp, this, in(MemNode::Address));
727 }
729 // I tried to leave the CastPP's in. This makes the graph more accurate in
730 // some sense; we get to keep around the knowledge that an oop is not-null
731 // after some test. Alas, the CastPP's interfere with GVN (some values are
732 // the regular oop, some are the CastPP of the oop, all merge at Phi's which
733 // cannot collapse, etc). This cost us 10% on SpecJVM, even when I removed
734 // some of the more trivial cases in the optimizer. Removing more useless
735 // Phi's started allowing Loads to illegally float above null checks. I gave
736 // up on this approach. CNC 10/20/2000
737 // This static method may be called not from MemNode (EncodePNode calls it).
738 // Only the control edge of the node 'n' might be updated.
739 Node *MemNode::Ideal_common_DU_postCCP( PhaseCCP *ccp, Node* n, Node* adr ) {
740 Node *skipped_cast = NULL;
741 // Need a null check? Regular static accesses do not because they are
742 // from constant addresses. Array ops are gated by the range check (which
743 // always includes a NULL check). Just check field ops.
744 if( n->in(MemNode::Control) == NULL ) {
745 // Scan upwards for the highest location we can place this memory op.
746 while( true ) {
747 switch( adr->Opcode() ) {
749 case Op_AddP: // No change to NULL-ness, so peek thru AddP's
750 adr = adr->in(AddPNode::Base);
751 continue;
753 case Op_DecodeN: // No change to NULL-ness, so peek thru
754 case Op_DecodeNKlass:
755 adr = adr->in(1);
756 continue;
758 case Op_EncodeP:
759 case Op_EncodePKlass:
760 // EncodeP node's control edge could be set by this method
761 // when EncodeP node depends on CastPP node.
762 //
763 // Use its control edge for memory op because EncodeP may go away
764 // later when it is folded with following or preceding DecodeN node.
765 if (adr->in(0) == NULL) {
766 // Keep looking for cast nodes.
767 adr = adr->in(1);
768 continue;
769 }
770 ccp->hash_delete(n);
771 n->set_req(MemNode::Control, adr->in(0));
772 ccp->hash_insert(n);
773 return n;
775 case Op_CastPP:
776 // If the CastPP is useless, just peek on through it.
777 if( ccp->type(adr) == ccp->type(adr->in(1)) ) {
778 // Remember the cast that we've peeked though. If we peek
779 // through more than one, then we end up remembering the highest
780 // one, that is, if in a loop, the one closest to the top.
781 skipped_cast = adr;
782 adr = adr->in(1);
783 continue;
784 }
785 // CastPP is going away in this pass! We need this memory op to be
786 // control-dependent on the test that is guarding the CastPP.
787 ccp->hash_delete(n);
788 n->set_req(MemNode::Control, adr->in(0));
789 ccp->hash_insert(n);
790 return n;
792 case Op_Phi:
793 // Attempt to float above a Phi to some dominating point.
794 if (adr->in(0) != NULL && adr->in(0)->is_CountedLoop()) {
795 // If we've already peeked through a Cast (which could have set the
796 // control), we can't float above a Phi, because the skipped Cast
797 // may not be loop invariant.
798 if (adr_phi_is_loop_invariant(adr, skipped_cast)) {
799 adr = adr->in(1);
800 continue;
801 }
802 }
804 // Intentional fallthrough!
806 // No obvious dominating point. The mem op is pinned below the Phi
807 // by the Phi itself. If the Phi goes away (no true value is merged)
808 // then the mem op can float, but not indefinitely. It must be pinned
809 // behind the controls leading to the Phi.
810 case Op_CheckCastPP:
811 // These usually stick around to change address type, however a
812 // useless one can be elided and we still need to pick up a control edge
813 if (adr->in(0) == NULL) {
814 // This CheckCastPP node has NO control and is likely useless. But we
815 // need check further up the ancestor chain for a control input to keep
816 // the node in place. 4959717.
817 skipped_cast = adr;
818 adr = adr->in(1);
819 continue;
820 }
821 ccp->hash_delete(n);
822 n->set_req(MemNode::Control, adr->in(0));
823 ccp->hash_insert(n);
824 return n;
826 // List of "safe" opcodes; those that implicitly block the memory
827 // op below any null check.
828 case Op_CastX2P: // no null checks on native pointers
829 case Op_Parm: // 'this' pointer is not null
830 case Op_LoadP: // Loading from within a klass
831 case Op_LoadN: // Loading from within a klass
832 case Op_LoadKlass: // Loading from within a klass
833 case Op_LoadNKlass: // Loading from within a klass
834 case Op_ConP: // Loading from a klass
835 case Op_ConN: // Loading from a klass
836 case Op_ConNKlass: // Loading from a klass
837 case Op_CreateEx: // Sucking up the guts of an exception oop
838 case Op_Con: // Reading from TLS
839 case Op_CMoveP: // CMoveP is pinned
840 case Op_CMoveN: // CMoveN is pinned
841 break; // No progress
843 case Op_Proj: // Direct call to an allocation routine
844 case Op_SCMemProj: // Memory state from store conditional ops
845 #ifdef ASSERT
846 {
847 assert(adr->as_Proj()->_con == TypeFunc::Parms, "must be return value");
848 const Node* call = adr->in(0);
849 if (call->is_CallJava()) {
850 const CallJavaNode* call_java = call->as_CallJava();
851 const TypeTuple *r = call_java->tf()->range();
852 assert(r->cnt() > TypeFunc::Parms, "must return value");
853 const Type* ret_type = r->field_at(TypeFunc::Parms);
854 assert(ret_type && ret_type->isa_ptr(), "must return pointer");
855 // We further presume that this is one of
856 // new_instance_Java, new_array_Java, or
857 // the like, but do not assert for this.
858 } else if (call->is_Allocate()) {
859 // similar case to new_instance_Java, etc.
860 } else if (!call->is_CallLeaf()) {
861 // Projections from fetch_oop (OSR) are allowed as well.
862 ShouldNotReachHere();
863 }
864 }
865 #endif
866 break;
867 default:
868 ShouldNotReachHere();
869 }
870 break;
871 }
872 }
874 return NULL; // No progress
875 }
878 //=============================================================================
879 uint LoadNode::size_of() const { return sizeof(*this); }
880 uint LoadNode::cmp( const Node &n ) const
881 { return !Type::cmp( _type, ((LoadNode&)n)._type ); }
882 const Type *LoadNode::bottom_type() const { return _type; }
883 uint LoadNode::ideal_reg() const {
884 return _type->ideal_reg();
885 }
887 #ifndef PRODUCT
888 void LoadNode::dump_spec(outputStream *st) const {
889 MemNode::dump_spec(st);
890 if( !Verbose && !WizardMode ) {
891 // standard dump does this in Verbose and WizardMode
892 st->print(" #"); _type->dump_on(st);
893 }
894 }
895 #endif
897 #ifdef ASSERT
898 //----------------------------is_immutable_value-------------------------------
899 // Helper function to allow a raw load without control edge for some cases
900 bool LoadNode::is_immutable_value(Node* adr) {
901 return (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() &&
902 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal &&
903 (adr->in(AddPNode::Offset)->find_intptr_t_con(-1) ==
904 in_bytes(JavaThread::osthread_offset())));
905 }
906 #endif
908 //----------------------------LoadNode::make-----------------------------------
909 // Polymorphic factory method:
910 Node *LoadNode::make( PhaseGVN& gvn, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt ) {
911 Compile* C = gvn.C;
913 // sanity check the alias category against the created node type
914 assert(!(adr_type->isa_oopptr() &&
915 adr_type->offset() == oopDesc::klass_offset_in_bytes()),
916 "use LoadKlassNode instead");
917 assert(!(adr_type->isa_aryptr() &&
918 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
919 "use LoadRangeNode instead");
920 // Check control edge of raw loads
921 assert( ctl != NULL || C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
922 // oop will be recorded in oop map if load crosses safepoint
923 rt->isa_oopptr() || is_immutable_value(adr),
924 "raw memory operations should have control edge");
925 switch (bt) {
926 case T_BOOLEAN: return new (C) LoadUBNode(ctl, mem, adr, adr_type, rt->is_int() );
927 case T_BYTE: return new (C) LoadBNode (ctl, mem, adr, adr_type, rt->is_int() );
928 case T_INT: return new (C) LoadINode (ctl, mem, adr, adr_type, rt->is_int() );
929 case T_CHAR: return new (C) LoadUSNode(ctl, mem, adr, adr_type, rt->is_int() );
930 case T_SHORT: return new (C) LoadSNode (ctl, mem, adr, adr_type, rt->is_int() );
931 case T_LONG: return new (C) LoadLNode (ctl, mem, adr, adr_type, rt->is_long() );
932 case T_FLOAT: return new (C) LoadFNode (ctl, mem, adr, adr_type, rt );
933 case T_DOUBLE: return new (C) LoadDNode (ctl, mem, adr, adr_type, rt );
934 case T_ADDRESS: return new (C) LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr() );
935 case T_OBJECT:
936 #ifdef _LP64
937 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
938 Node* load = gvn.transform(new (C) LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop()));
939 return new (C) DecodeNNode(load, load->bottom_type()->make_ptr());
940 } else
941 #endif
942 {
943 assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop");
944 return new (C) LoadPNode(ctl, mem, adr, adr_type, rt->is_oopptr());
945 }
946 }
947 ShouldNotReachHere();
948 return (LoadNode*)NULL;
949 }
951 LoadLNode* LoadLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt) {
952 bool require_atomic = true;
953 return new (C) LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), require_atomic);
954 }
959 //------------------------------hash-------------------------------------------
960 uint LoadNode::hash() const {
961 // unroll addition of interesting fields
962 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
963 }
965 //---------------------------can_see_stored_value------------------------------
966 // This routine exists to make sure this set of tests is done the same
967 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
968 // will change the graph shape in a way which makes memory alive twice at the
969 // same time (uses the Oracle model of aliasing), then some
970 // LoadXNode::Identity will fold things back to the equivalence-class model
971 // of aliasing.
972 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const {
973 Node* ld_adr = in(MemNode::Address);
974 intptr_t ld_off = 0;
975 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
976 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
977 Compile::AliasType* atp = (tp != NULL) ? phase->C->alias_type(tp) : NULL;
978 // This is more general than load from boxing objects.
979 if (phase->C->eliminate_boxing() && (atp != NULL) &&
980 (atp->index() >= Compile::AliasIdxRaw) &&
981 (atp->field() != NULL) && !atp->field()->is_volatile()) {
982 uint alias_idx = atp->index();
983 bool final = atp->field()->is_final();
984 Node* result = NULL;
985 Node* current = st;
986 // Skip through chains of MemBarNodes checking the MergeMems for
987 // new states for the slice of this load. Stop once any other
988 // kind of node is encountered. Loads from final memory can skip
989 // through any kind of MemBar but normal loads shouldn't skip
990 // through MemBarAcquire since the could allow them to move out of
991 // a synchronized region.
992 while (current->is_Proj()) {
993 int opc = current->in(0)->Opcode();
994 if ((final && (opc == Op_MemBarAcquire || opc == Op_MemBarAcquireLock)) ||
995 opc == Op_MemBarRelease || opc == Op_MemBarCPUOrder ||
996 opc == Op_MemBarReleaseLock) {
997 Node* mem = current->in(0)->in(TypeFunc::Memory);
998 if (mem->is_MergeMem()) {
999 MergeMemNode* merge = mem->as_MergeMem();
1000 Node* new_st = merge->memory_at(alias_idx);
1001 if (new_st == merge->base_memory()) {
1002 // Keep searching
1003 current = new_st;
1004 continue;
1005 }
1006 // Save the new memory state for the slice and fall through
1007 // to exit.
1008 result = new_st;
1009 }
1010 }
1011 break;
1012 }
1013 if (result != NULL) {
1014 st = result;
1015 }
1016 }
1019 // Loop around twice in the case Load -> Initialize -> Store.
1020 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
1021 for (int trip = 0; trip <= 1; trip++) {
1023 if (st->is_Store()) {
1024 Node* st_adr = st->in(MemNode::Address);
1025 if (!phase->eqv(st_adr, ld_adr)) {
1026 // Try harder before giving up... Match raw and non-raw pointers.
1027 intptr_t st_off = 0;
1028 AllocateNode* alloc = AllocateNode::Ideal_allocation(st_adr, phase, st_off);
1029 if (alloc == NULL) return NULL;
1030 if (alloc != ld_alloc) return NULL;
1031 if (ld_off != st_off) return NULL;
1032 // At this point we have proven something like this setup:
1033 // A = Allocate(...)
1034 // L = LoadQ(, AddP(CastPP(, A.Parm),, #Off))
1035 // S = StoreQ(, AddP(, A.Parm , #Off), V)
1036 // (Actually, we haven't yet proven the Q's are the same.)
1037 // In other words, we are loading from a casted version of
1038 // the same pointer-and-offset that we stored to.
1039 // Thus, we are able to replace L by V.
1040 }
1041 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
1042 if (store_Opcode() != st->Opcode())
1043 return NULL;
1044 return st->in(MemNode::ValueIn);
1045 }
1047 // A load from a freshly-created object always returns zero.
1048 // (This can happen after LoadNode::Ideal resets the load's memory input
1049 // to find_captured_store, which returned InitializeNode::zero_memory.)
1050 if (st->is_Proj() && st->in(0)->is_Allocate() &&
1051 (st->in(0) == ld_alloc) &&
1052 (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) {
1053 // return a zero value for the load's basic type
1054 // (This is one of the few places where a generic PhaseTransform
1055 // can create new nodes. Think of it as lazily manifesting
1056 // virtually pre-existing constants.)
1057 return phase->zerocon(memory_type());
1058 }
1060 // A load from an initialization barrier can match a captured store.
1061 if (st->is_Proj() && st->in(0)->is_Initialize()) {
1062 InitializeNode* init = st->in(0)->as_Initialize();
1063 AllocateNode* alloc = init->allocation();
1064 if ((alloc != NULL) && (alloc == ld_alloc)) {
1065 // examine a captured store value
1066 st = init->find_captured_store(ld_off, memory_size(), phase);
1067 if (st != NULL)
1068 continue; // take one more trip around
1069 }
1070 }
1072 // Load boxed value from result of valueOf() call is input parameter.
1073 if (this->is_Load() && ld_adr->is_AddP() &&
1074 (tp != NULL) && tp->is_ptr_to_boxed_value()) {
1075 intptr_t ignore = 0;
1076 Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore);
1077 if (base != NULL && base->is_Proj() &&
1078 base->as_Proj()->_con == TypeFunc::Parms &&
1079 base->in(0)->is_CallStaticJava() &&
1080 base->in(0)->as_CallStaticJava()->is_boxing_method()) {
1081 return base->in(0)->in(TypeFunc::Parms);
1082 }
1083 }
1085 break;
1086 }
1088 return NULL;
1089 }
1091 //----------------------is_instance_field_load_with_local_phi------------------
1092 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
1093 if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl &&
1094 in(Address)->is_AddP() ) {
1095 const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr();
1096 // Only instances and boxed values.
1097 if( t_oop != NULL &&
1098 (t_oop->is_ptr_to_boxed_value() ||
1099 t_oop->is_known_instance_field()) &&
1100 t_oop->offset() != Type::OffsetBot &&
1101 t_oop->offset() != Type::OffsetTop) {
1102 return true;
1103 }
1104 }
1105 return false;
1106 }
1108 //------------------------------Identity---------------------------------------
1109 // Loads are identity if previous store is to same address
1110 Node *LoadNode::Identity( PhaseTransform *phase ) {
1111 // If the previous store-maker is the right kind of Store, and the store is
1112 // to the same address, then we are equal to the value stored.
1113 Node* mem = in(Memory);
1114 Node* value = can_see_stored_value(mem, phase);
1115 if( value ) {
1116 // byte, short & char stores truncate naturally.
1117 // A load has to load the truncated value which requires
1118 // some sort of masking operation and that requires an
1119 // Ideal call instead of an Identity call.
1120 if (memory_size() < BytesPerInt) {
1121 // If the input to the store does not fit with the load's result type,
1122 // it must be truncated via an Ideal call.
1123 if (!phase->type(value)->higher_equal(phase->type(this)))
1124 return this;
1125 }
1126 // (This works even when value is a Con, but LoadNode::Value
1127 // usually runs first, producing the singleton type of the Con.)
1128 return value;
1129 }
1131 // Search for an existing data phi which was generated before for the same
1132 // instance's field to avoid infinite generation of phis in a loop.
1133 Node *region = mem->in(0);
1134 if (is_instance_field_load_with_local_phi(region)) {
1135 const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr();
1136 int this_index = phase->C->get_alias_index(addr_t);
1137 int this_offset = addr_t->offset();
1138 int this_iid = addr_t->instance_id();
1139 if (!addr_t->is_known_instance() &&
1140 addr_t->is_ptr_to_boxed_value()) {
1141 // Use _idx of address base (could be Phi node) for boxed values.
1142 intptr_t ignore = 0;
1143 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1144 this_iid = base->_idx;
1145 }
1146 const Type* this_type = bottom_type();
1147 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1148 Node* phi = region->fast_out(i);
1149 if (phi->is_Phi() && phi != mem &&
1150 phi->as_Phi()->is_same_inst_field(this_type, this_iid, this_index, this_offset)) {
1151 return phi;
1152 }
1153 }
1154 }
1156 return this;
1157 }
1159 // We're loading from an object which has autobox behaviour.
1160 // If this object is result of a valueOf call we'll have a phi
1161 // merging a newly allocated object and a load from the cache.
1162 // We want to replace this load with the original incoming
1163 // argument to the valueOf call.
1164 Node* LoadNode::eliminate_autobox(PhaseGVN* phase) {
1165 assert(phase->C->eliminate_boxing(), "sanity");
1166 intptr_t ignore = 0;
1167 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1168 if ((base == NULL) || base->is_Phi()) {
1169 // Push the loads from the phi that comes from valueOf up
1170 // through it to allow elimination of the loads and the recovery
1171 // of the original value. It is done in split_through_phi().
1172 return NULL;
1173 } else if (base->is_Load() ||
1174 base->is_DecodeN() && base->in(1)->is_Load()) {
1175 // Eliminate the load of boxed value for integer types from the cache
1176 // array by deriving the value from the index into the array.
1177 // Capture the offset of the load and then reverse the computation.
1179 // Get LoadN node which loads a boxing object from 'cache' array.
1180 if (base->is_DecodeN()) {
1181 base = base->in(1);
1182 }
1183 if (!base->in(Address)->is_AddP()) {
1184 return NULL; // Complex address
1185 }
1186 AddPNode* address = base->in(Address)->as_AddP();
1187 Node* cache_base = address->in(AddPNode::Base);
1188 if ((cache_base != NULL) && cache_base->is_DecodeN()) {
1189 // Get ConP node which is static 'cache' field.
1190 cache_base = cache_base->in(1);
1191 }
1192 if ((cache_base != NULL) && cache_base->is_Con()) {
1193 const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr();
1194 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1195 Node* elements[4];
1196 int shift = exact_log2(type2aelembytes(T_OBJECT));
1197 int count = address->unpack_offsets(elements, ARRAY_SIZE(elements));
1198 if ((count > 0) && elements[0]->is_Con() &&
1199 ((count == 1) ||
1200 (count == 2) && elements[1]->Opcode() == Op_LShiftX &&
1201 elements[1]->in(2) == phase->intcon(shift))) {
1202 ciObjArray* array = base_type->const_oop()->as_obj_array();
1203 // Fetch the box object cache[0] at the base of the array and get its value
1204 ciInstance* box = array->obj_at(0)->as_instance();
1205 ciInstanceKlass* ik = box->klass()->as_instance_klass();
1206 assert(ik->is_box_klass(), "sanity");
1207 assert(ik->nof_nonstatic_fields() == 1, "change following code");
1208 if (ik->nof_nonstatic_fields() == 1) {
1209 // This should be true nonstatic_field_at requires calling
1210 // nof_nonstatic_fields so check it anyway
1211 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1212 BasicType bt = c.basic_type();
1213 // Only integer types have boxing cache.
1214 assert(bt == T_BOOLEAN || bt == T_CHAR ||
1215 bt == T_BYTE || bt == T_SHORT ||
1216 bt == T_INT || bt == T_LONG, err_msg_res("wrong type = %s", type2name(bt)));
1217 jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int();
1218 if (cache_low != (int)cache_low) {
1219 return NULL; // should not happen since cache is array indexed by value
1220 }
1221 jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift);
1222 if (offset != (int)offset) {
1223 return NULL; // should not happen since cache is array indexed by value
1224 }
1225 // Add up all the offsets making of the address of the load
1226 Node* result = elements[0];
1227 for (int i = 1; i < count; i++) {
1228 result = phase->transform(new (phase->C) AddXNode(result, elements[i]));
1229 }
1230 // Remove the constant offset from the address and then
1231 result = phase->transform(new (phase->C) AddXNode(result, phase->MakeConX(-(int)offset)));
1232 // remove the scaling of the offset to recover the original index.
1233 if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) {
1234 // Peel the shift off directly but wrap it in a dummy node
1235 // since Ideal can't return existing nodes
1236 result = new (phase->C) RShiftXNode(result->in(1), phase->intcon(0));
1237 } else if (result->is_Add() && result->in(2)->is_Con() &&
1238 result->in(1)->Opcode() == Op_LShiftX &&
1239 result->in(1)->in(2) == phase->intcon(shift)) {
1240 // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z)
1241 // but for boxing cache access we know that X<<Z will not overflow
1242 // (there is range check) so we do this optimizatrion by hand here.
1243 Node* add_con = new (phase->C) RShiftXNode(result->in(2), phase->intcon(shift));
1244 result = new (phase->C) AddXNode(result->in(1)->in(1), phase->transform(add_con));
1245 } else {
1246 result = new (phase->C) RShiftXNode(result, phase->intcon(shift));
1247 }
1248 #ifdef _LP64
1249 if (bt != T_LONG) {
1250 result = new (phase->C) ConvL2INode(phase->transform(result));
1251 }
1252 #else
1253 if (bt == T_LONG) {
1254 result = new (phase->C) ConvI2LNode(phase->transform(result));
1255 }
1256 #endif
1257 return result;
1258 }
1259 }
1260 }
1261 }
1262 }
1263 return NULL;
1264 }
1266 static bool stable_phi(PhiNode* phi, PhaseGVN *phase) {
1267 Node* region = phi->in(0);
1268 if (region == NULL) {
1269 return false; // Wait stable graph
1270 }
1271 uint cnt = phi->req();
1272 for (uint i = 1; i < cnt; i++) {
1273 Node* rc = region->in(i);
1274 if (rc == NULL || phase->type(rc) == Type::TOP)
1275 return false; // Wait stable graph
1276 Node* in = phi->in(i);
1277 if (in == NULL || phase->type(in) == Type::TOP)
1278 return false; // Wait stable graph
1279 }
1280 return true;
1281 }
1282 //------------------------------split_through_phi------------------------------
1283 // Split instance or boxed field load through Phi.
1284 Node *LoadNode::split_through_phi(PhaseGVN *phase) {
1285 Node* mem = in(Memory);
1286 Node* address = in(Address);
1287 const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr();
1289 assert((t_oop != NULL) &&
1290 (t_oop->is_known_instance_field() ||
1291 t_oop->is_ptr_to_boxed_value()), "invalide conditions");
1293 Compile* C = phase->C;
1294 intptr_t ignore = 0;
1295 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1296 bool base_is_phi = (base != NULL) && base->is_Phi();
1297 bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() &&
1298 (base != NULL) && (base == address->in(AddPNode::Base)) &&
1299 phase->type(base)->higher_equal(TypePtr::NOTNULL);
1301 if (!((mem->is_Phi() || base_is_phi) &&
1302 (load_boxed_values || t_oop->is_known_instance_field()))) {
1303 return NULL; // memory is not Phi
1304 }
1306 if (mem->is_Phi()) {
1307 if (!stable_phi(mem->as_Phi(), phase)) {
1308 return NULL; // Wait stable graph
1309 }
1310 uint cnt = mem->req();
1311 // Check for loop invariant memory.
1312 if (cnt == 3) {
1313 for (uint i = 1; i < cnt; i++) {
1314 Node* in = mem->in(i);
1315 Node* m = optimize_memory_chain(in, t_oop, this, phase);
1316 if (m == mem) {
1317 set_req(Memory, mem->in(cnt - i));
1318 return this; // made change
1319 }
1320 }
1321 }
1322 }
1323 if (base_is_phi) {
1324 if (!stable_phi(base->as_Phi(), phase)) {
1325 return NULL; // Wait stable graph
1326 }
1327 uint cnt = base->req();
1328 // Check for loop invariant memory.
1329 if (cnt == 3) {
1330 for (uint i = 1; i < cnt; i++) {
1331 if (base->in(i) == base) {
1332 return NULL; // Wait stable graph
1333 }
1334 }
1335 }
1336 }
1338 bool load_boxed_phi = load_boxed_values && base_is_phi && (base->in(0) == mem->in(0));
1340 // Split through Phi (see original code in loopopts.cpp).
1341 assert(C->have_alias_type(t_oop), "instance should have alias type");
1343 // Do nothing here if Identity will find a value
1344 // (to avoid infinite chain of value phis generation).
1345 if (!phase->eqv(this, this->Identity(phase)))
1346 return NULL;
1348 // Select Region to split through.
1349 Node* region;
1350 if (!base_is_phi) {
1351 assert(mem->is_Phi(), "sanity");
1352 region = mem->in(0);
1353 // Skip if the region dominates some control edge of the address.
1354 if (!MemNode::all_controls_dominate(address, region))
1355 return NULL;
1356 } else if (!mem->is_Phi()) {
1357 assert(base_is_phi, "sanity");
1358 region = base->in(0);
1359 // Skip if the region dominates some control edge of the memory.
1360 if (!MemNode::all_controls_dominate(mem, region))
1361 return NULL;
1362 } else if (base->in(0) != mem->in(0)) {
1363 assert(base_is_phi && mem->is_Phi(), "sanity");
1364 if (MemNode::all_controls_dominate(mem, base->in(0))) {
1365 region = base->in(0);
1366 } else if (MemNode::all_controls_dominate(address, mem->in(0))) {
1367 region = mem->in(0);
1368 } else {
1369 return NULL; // complex graph
1370 }
1371 } else {
1372 assert(base->in(0) == mem->in(0), "sanity");
1373 region = mem->in(0);
1374 }
1376 const Type* this_type = this->bottom_type();
1377 int this_index = C->get_alias_index(t_oop);
1378 int this_offset = t_oop->offset();
1379 int this_iid = t_oop->instance_id();
1380 if (!t_oop->is_known_instance() && load_boxed_values) {
1381 // Use _idx of address base for boxed values.
1382 this_iid = base->_idx;
1383 }
1384 PhaseIterGVN* igvn = phase->is_IterGVN();
1385 Node* phi = new (C) PhiNode(region, this_type, NULL, this_iid, this_index, this_offset);
1386 for (uint i = 1; i < region->req(); i++) {
1387 Node* x;
1388 Node* the_clone = NULL;
1389 if (region->in(i) == C->top()) {
1390 x = C->top(); // Dead path? Use a dead data op
1391 } else {
1392 x = this->clone(); // Else clone up the data op
1393 the_clone = x; // Remember for possible deletion.
1394 // Alter data node to use pre-phi inputs
1395 if (this->in(0) == region) {
1396 x->set_req(0, region->in(i));
1397 } else {
1398 x->set_req(0, NULL);
1399 }
1400 if (mem->is_Phi() && (mem->in(0) == region)) {
1401 x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone.
1402 }
1403 if (address->is_Phi() && address->in(0) == region) {
1404 x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone
1405 }
1406 if (base_is_phi && (base->in(0) == region)) {
1407 Node* base_x = base->in(i); // Clone address for loads from boxed objects.
1408 Node* adr_x = phase->transform(new (C) AddPNode(base_x,base_x,address->in(AddPNode::Offset)));
1409 x->set_req(Address, adr_x);
1410 }
1411 }
1412 // Check for a 'win' on some paths
1413 const Type *t = x->Value(igvn);
1415 bool singleton = t->singleton();
1417 // See comments in PhaseIdealLoop::split_thru_phi().
1418 if (singleton && t == Type::TOP) {
1419 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1420 }
1422 if (singleton) {
1423 x = igvn->makecon(t);
1424 } else {
1425 // We now call Identity to try to simplify the cloned node.
1426 // Note that some Identity methods call phase->type(this).
1427 // Make sure that the type array is big enough for
1428 // our new node, even though we may throw the node away.
1429 // (This tweaking with igvn only works because x is a new node.)
1430 igvn->set_type(x, t);
1431 // If x is a TypeNode, capture any more-precise type permanently into Node
1432 // otherwise it will be not updated during igvn->transform since
1433 // igvn->type(x) is set to x->Value() already.
1434 x->raise_bottom_type(t);
1435 Node *y = x->Identity(igvn);
1436 if (y != x) {
1437 x = y;
1438 } else {
1439 y = igvn->hash_find_insert(x);
1440 if (y) {
1441 x = y;
1442 } else {
1443 // Else x is a new node we are keeping
1444 // We do not need register_new_node_with_optimizer
1445 // because set_type has already been called.
1446 igvn->_worklist.push(x);
1447 }
1448 }
1449 }
1450 if (x != the_clone && the_clone != NULL) {
1451 igvn->remove_dead_node(the_clone);
1452 }
1453 phi->set_req(i, x);
1454 }
1455 // Record Phi
1456 igvn->register_new_node_with_optimizer(phi);
1457 return phi;
1458 }
1460 //------------------------------Ideal------------------------------------------
1461 // If the load is from Field memory and the pointer is non-null, we can
1462 // zero out the control input.
1463 // If the offset is constant and the base is an object allocation,
1464 // try to hook me up to the exact initializing store.
1465 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1466 Node* p = MemNode::Ideal_common(phase, can_reshape);
1467 if (p) return (p == NodeSentinel) ? NULL : p;
1469 Node* ctrl = in(MemNode::Control);
1470 Node* address = in(MemNode::Address);
1472 // Skip up past a SafePoint control. Cannot do this for Stores because
1473 // pointer stores & cardmarks must stay on the same side of a SafePoint.
1474 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint &&
1475 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw ) {
1476 ctrl = ctrl->in(0);
1477 set_req(MemNode::Control,ctrl);
1478 }
1480 intptr_t ignore = 0;
1481 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1482 if (base != NULL
1483 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
1484 // Check for useless control edge in some common special cases
1485 if (in(MemNode::Control) != NULL
1486 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1487 && all_controls_dominate(base, phase->C->start())) {
1488 // A method-invariant, non-null address (constant or 'this' argument).
1489 set_req(MemNode::Control, NULL);
1490 }
1491 }
1493 Node* mem = in(MemNode::Memory);
1494 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1496 if (can_reshape && (addr_t != NULL)) {
1497 // try to optimize our memory input
1498 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase);
1499 if (opt_mem != mem) {
1500 set_req(MemNode::Memory, opt_mem);
1501 if (phase->type( opt_mem ) == Type::TOP) return NULL;
1502 return this;
1503 }
1504 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1505 if ((t_oop != NULL) &&
1506 (t_oop->is_known_instance_field() ||
1507 t_oop->is_ptr_to_boxed_value())) {
1508 PhaseIterGVN *igvn = phase->is_IterGVN();
1509 if (igvn != NULL && igvn->_worklist.member(opt_mem)) {
1510 // Delay this transformation until memory Phi is processed.
1511 phase->is_IterGVN()->_worklist.push(this);
1512 return NULL;
1513 }
1514 // Split instance field load through Phi.
1515 Node* result = split_through_phi(phase);
1516 if (result != NULL) return result;
1518 if (t_oop->is_ptr_to_boxed_value()) {
1519 Node* result = eliminate_autobox(phase);
1520 if (result != NULL) return result;
1521 }
1522 }
1523 }
1525 // Check for prior store with a different base or offset; make Load
1526 // independent. Skip through any number of them. Bail out if the stores
1527 // are in an endless dead cycle and report no progress. This is a key
1528 // transform for Reflection. However, if after skipping through the Stores
1529 // we can't then fold up against a prior store do NOT do the transform as
1530 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
1531 // array memory alive twice: once for the hoisted Load and again after the
1532 // bypassed Store. This situation only works if EVERYBODY who does
1533 // anti-dependence work knows how to bypass. I.e. we need all
1534 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
1535 // the alias index stuff. So instead, peek through Stores and IFF we can
1536 // fold up, do so.
1537 Node* prev_mem = find_previous_store(phase);
1538 // Steps (a), (b): Walk past independent stores to find an exact match.
1539 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) {
1540 // (c) See if we can fold up on the spot, but don't fold up here.
1541 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
1542 // just return a prior value, which is done by Identity calls.
1543 if (can_see_stored_value(prev_mem, phase)) {
1544 // Make ready for step (d):
1545 set_req(MemNode::Memory, prev_mem);
1546 return this;
1547 }
1548 }
1550 return NULL; // No further progress
1551 }
1553 // Helper to recognize certain Klass fields which are invariant across
1554 // some group of array types (e.g., int[] or all T[] where T < Object).
1555 const Type*
1556 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1557 ciKlass* klass) const {
1558 if (tkls->offset() == in_bytes(Klass::modifier_flags_offset())) {
1559 // The field is Klass::_modifier_flags. Return its (constant) value.
1560 // (Folds up the 2nd indirection in aClassConstant.getModifiers().)
1561 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags");
1562 return TypeInt::make(klass->modifier_flags());
1563 }
1564 if (tkls->offset() == in_bytes(Klass::access_flags_offset())) {
1565 // The field is Klass::_access_flags. Return its (constant) value.
1566 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1567 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags");
1568 return TypeInt::make(klass->access_flags());
1569 }
1570 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) {
1571 // The field is Klass::_layout_helper. Return its constant value if known.
1572 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper");
1573 return TypeInt::make(klass->layout_helper());
1574 }
1576 // No match.
1577 return NULL;
1578 }
1580 //------------------------------Value-----------------------------------------
1581 const Type *LoadNode::Value( PhaseTransform *phase ) const {
1582 // Either input is TOP ==> the result is TOP
1583 Node* mem = in(MemNode::Memory);
1584 const Type *t1 = phase->type(mem);
1585 if (t1 == Type::TOP) return Type::TOP;
1586 Node* adr = in(MemNode::Address);
1587 const TypePtr* tp = phase->type(adr)->isa_ptr();
1588 if (tp == NULL || tp->empty()) return Type::TOP;
1589 int off = tp->offset();
1590 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
1591 Compile* C = phase->C;
1593 // Try to guess loaded type from pointer type
1594 if (tp->base() == Type::AryPtr) {
1595 const Type *t = tp->is_aryptr()->elem();
1596 // Don't do this for integer types. There is only potential profit if
1597 // the element type t is lower than _type; that is, for int types, if _type is
1598 // more restrictive than t. This only happens here if one is short and the other
1599 // char (both 16 bits), and in those cases we've made an intentional decision
1600 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
1601 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
1602 //
1603 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
1604 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
1605 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
1606 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
1607 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
1608 // In fact, that could have been the original type of p1, and p1 could have
1609 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
1610 // expression (LShiftL quux 3) independently optimized to the constant 8.
1611 if ((t->isa_int() == NULL) && (t->isa_long() == NULL)
1612 && (_type->isa_vect() == NULL)
1613 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
1614 // t might actually be lower than _type, if _type is a unique
1615 // concrete subclass of abstract class t.
1616 // Make sure the reference is not into the header, by comparing
1617 // the offset against the offset of the start of the array's data.
1618 // Different array types begin at slightly different offsets (12 vs. 16).
1619 // We choose T_BYTE as an example base type that is least restrictive
1620 // as to alignment, which will therefore produce the smallest
1621 // possible base offset.
1622 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
1623 if ((uint)off >= (uint)min_base_off) { // is the offset beyond the header?
1624 const Type* jt = t->join(_type);
1625 // In any case, do not allow the join, per se, to empty out the type.
1626 if (jt->empty() && !t->empty()) {
1627 // This can happen if a interface-typed array narrows to a class type.
1628 jt = _type;
1629 }
1630 #ifdef ASSERT
1631 if (phase->C->eliminate_boxing() && adr->is_AddP()) {
1632 // The pointers in the autobox arrays are always non-null
1633 Node* base = adr->in(AddPNode::Base);
1634 if ((base != NULL) && base->is_DecodeN()) {
1635 // Get LoadN node which loads IntegerCache.cache field
1636 base = base->in(1);
1637 }
1638 if ((base != NULL) && base->is_Con()) {
1639 const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr();
1640 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1641 // It could be narrow oop
1642 assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity");
1643 }
1644 }
1645 }
1646 #endif
1647 return jt;
1648 }
1649 }
1650 } else if (tp->base() == Type::InstPtr) {
1651 ciEnv* env = C->env();
1652 const TypeInstPtr* tinst = tp->is_instptr();
1653 ciKlass* klass = tinst->klass();
1654 assert( off != Type::OffsetBot ||
1655 // arrays can be cast to Objects
1656 tp->is_oopptr()->klass()->is_java_lang_Object() ||
1657 // unsafe field access may not have a constant offset
1658 C->has_unsafe_access(),
1659 "Field accesses must be precise" );
1660 // For oop loads, we expect the _type to be precise
1661 if (klass == env->String_klass() &&
1662 adr->is_AddP() && off != Type::OffsetBot) {
1663 // For constant Strings treat the final fields as compile time constants.
1664 Node* base = adr->in(AddPNode::Base);
1665 const TypeOopPtr* t = phase->type(base)->isa_oopptr();
1666 if (t != NULL && t->singleton()) {
1667 ciField* field = env->String_klass()->get_field_by_offset(off, false);
1668 if (field != NULL && field->is_final()) {
1669 ciObject* string = t->const_oop();
1670 ciConstant constant = string->as_instance()->field_value(field);
1671 if (constant.basic_type() == T_INT) {
1672 return TypeInt::make(constant.as_int());
1673 } else if (constant.basic_type() == T_ARRAY) {
1674 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
1675 return TypeNarrowOop::make_from_constant(constant.as_object(), true);
1676 } else {
1677 return TypeOopPtr::make_from_constant(constant.as_object(), true);
1678 }
1679 }
1680 }
1681 }
1682 }
1683 // Optimizations for constant objects
1684 ciObject* const_oop = tinst->const_oop();
1685 if (const_oop != NULL) {
1686 // For constant Boxed value treat the target field as a compile time constant.
1687 if (tinst->is_ptr_to_boxed_value()) {
1688 return tinst->get_const_boxed_value();
1689 } else
1690 // For constant CallSites treat the target field as a compile time constant.
1691 if (const_oop->is_call_site()) {
1692 ciCallSite* call_site = const_oop->as_call_site();
1693 ciField* field = call_site->klass()->as_instance_klass()->get_field_by_offset(off, /*is_static=*/ false);
1694 if (field != NULL && field->is_call_site_target()) {
1695 ciMethodHandle* target = call_site->get_target();
1696 if (target != NULL) { // just in case
1697 ciConstant constant(T_OBJECT, target);
1698 const Type* t;
1699 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
1700 t = TypeNarrowOop::make_from_constant(constant.as_object(), true);
1701 } else {
1702 t = TypeOopPtr::make_from_constant(constant.as_object(), true);
1703 }
1704 // Add a dependence for invalidation of the optimization.
1705 if (!call_site->is_constant_call_site()) {
1706 C->dependencies()->assert_call_site_target_value(call_site, target);
1707 }
1708 return t;
1709 }
1710 }
1711 }
1712 }
1713 } else if (tp->base() == Type::KlassPtr) {
1714 assert( off != Type::OffsetBot ||
1715 // arrays can be cast to Objects
1716 tp->is_klassptr()->klass()->is_java_lang_Object() ||
1717 // also allow array-loading from the primary supertype
1718 // array during subtype checks
1719 Opcode() == Op_LoadKlass,
1720 "Field accesses must be precise" );
1721 // For klass/static loads, we expect the _type to be precise
1722 }
1724 const TypeKlassPtr *tkls = tp->isa_klassptr();
1725 if (tkls != NULL && !StressReflectiveCode) {
1726 ciKlass* klass = tkls->klass();
1727 if (klass->is_loaded() && tkls->klass_is_exact()) {
1728 // We are loading a field from a Klass metaobject whose identity
1729 // is known at compile time (the type is "exact" or "precise").
1730 // Check for fields we know are maintained as constants by the VM.
1731 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) {
1732 // The field is Klass::_super_check_offset. Return its (constant) value.
1733 // (Folds up type checking code.)
1734 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
1735 return TypeInt::make(klass->super_check_offset());
1736 }
1737 // Compute index into primary_supers array
1738 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1739 // Check for overflowing; use unsigned compare to handle the negative case.
1740 if( depth < ciKlass::primary_super_limit() ) {
1741 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1742 // (Folds up type checking code.)
1743 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1744 ciKlass *ss = klass->super_of_depth(depth);
1745 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1746 }
1747 const Type* aift = load_array_final_field(tkls, klass);
1748 if (aift != NULL) return aift;
1749 if (tkls->offset() == in_bytes(ArrayKlass::component_mirror_offset())
1750 && klass->is_array_klass()) {
1751 // The field is ArrayKlass::_component_mirror. Return its (constant) value.
1752 // (Folds up aClassConstant.getComponentType, common in Arrays.copyOf.)
1753 assert(Opcode() == Op_LoadP, "must load an oop from _component_mirror");
1754 return TypeInstPtr::make(klass->as_array_klass()->component_mirror());
1755 }
1756 if (tkls->offset() == in_bytes(Klass::java_mirror_offset())) {
1757 // The field is Klass::_java_mirror. Return its (constant) value.
1758 // (Folds up the 2nd indirection in anObjConstant.getClass().)
1759 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
1760 return TypeInstPtr::make(klass->java_mirror());
1761 }
1762 }
1764 // We can still check if we are loading from the primary_supers array at a
1765 // shallow enough depth. Even though the klass is not exact, entries less
1766 // than or equal to its super depth are correct.
1767 if (klass->is_loaded() ) {
1768 ciType *inner = klass;
1769 while( inner->is_obj_array_klass() )
1770 inner = inner->as_obj_array_klass()->base_element_type();
1771 if( inner->is_instance_klass() &&
1772 !inner->as_instance_klass()->flags().is_interface() ) {
1773 // Compute index into primary_supers array
1774 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1775 // Check for overflowing; use unsigned compare to handle the negative case.
1776 if( depth < ciKlass::primary_super_limit() &&
1777 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case
1778 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1779 // (Folds up type checking code.)
1780 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1781 ciKlass *ss = klass->super_of_depth(depth);
1782 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1783 }
1784 }
1785 }
1787 // If the type is enough to determine that the thing is not an array,
1788 // we can give the layout_helper a positive interval type.
1789 // This will help short-circuit some reflective code.
1790 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())
1791 && !klass->is_array_klass() // not directly typed as an array
1792 && !klass->is_interface() // specifically not Serializable & Cloneable
1793 && !klass->is_java_lang_Object() // not the supertype of all T[]
1794 ) {
1795 // Note: When interfaces are reliable, we can narrow the interface
1796 // test to (klass != Serializable && klass != Cloneable).
1797 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
1798 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
1799 // The key property of this type is that it folds up tests
1800 // for array-ness, since it proves that the layout_helper is positive.
1801 // Thus, a generic value like the basic object layout helper works fine.
1802 return TypeInt::make(min_size, max_jint, Type::WidenMin);
1803 }
1804 }
1806 // If we are loading from a freshly-allocated object, produce a zero,
1807 // if the load is provably beyond the header of the object.
1808 // (Also allow a variable load from a fresh array to produce zero.)
1809 const TypeOopPtr *tinst = tp->isa_oopptr();
1810 bool is_instance = (tinst != NULL) && tinst->is_known_instance_field();
1811 bool is_boxed_value = (tinst != NULL) && tinst->is_ptr_to_boxed_value();
1812 if (ReduceFieldZeroing || is_instance || is_boxed_value) {
1813 Node* value = can_see_stored_value(mem,phase);
1814 if (value != NULL && value->is_Con()) {
1815 assert(value->bottom_type()->higher_equal(_type),"sanity");
1816 return value->bottom_type();
1817 }
1818 }
1820 if (is_instance) {
1821 // If we have an instance type and our memory input is the
1822 // programs's initial memory state, there is no matching store,
1823 // so just return a zero of the appropriate type
1824 Node *mem = in(MemNode::Memory);
1825 if (mem->is_Parm() && mem->in(0)->is_Start()) {
1826 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
1827 return Type::get_zero_type(_type->basic_type());
1828 }
1829 }
1830 return _type;
1831 }
1833 //------------------------------match_edge-------------------------------------
1834 // Do we Match on this edge index or not? Match only the address.
1835 uint LoadNode::match_edge(uint idx) const {
1836 return idx == MemNode::Address;
1837 }
1839 //--------------------------LoadBNode::Ideal--------------------------------------
1840 //
1841 // If the previous store is to the same address as this load,
1842 // and the value stored was larger than a byte, replace this load
1843 // with the value stored truncated to a byte. If no truncation is
1844 // needed, the replacement is done in LoadNode::Identity().
1845 //
1846 Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1847 Node* mem = in(MemNode::Memory);
1848 Node* value = can_see_stored_value(mem,phase);
1849 if( value && !phase->type(value)->higher_equal( _type ) ) {
1850 Node *result = phase->transform( new (phase->C) LShiftINode(value, phase->intcon(24)) );
1851 return new (phase->C) RShiftINode(result, phase->intcon(24));
1852 }
1853 // Identity call will handle the case where truncation is not needed.
1854 return LoadNode::Ideal(phase, can_reshape);
1855 }
1857 const Type* LoadBNode::Value(PhaseTransform *phase) const {
1858 Node* mem = in(MemNode::Memory);
1859 Node* value = can_see_stored_value(mem,phase);
1860 if (value != NULL && value->is_Con() &&
1861 !value->bottom_type()->higher_equal(_type)) {
1862 // If the input to the store does not fit with the load's result type,
1863 // it must be truncated. We can't delay until Ideal call since
1864 // a singleton Value is needed for split_thru_phi optimization.
1865 int con = value->get_int();
1866 return TypeInt::make((con << 24) >> 24);
1867 }
1868 return LoadNode::Value(phase);
1869 }
1871 //--------------------------LoadUBNode::Ideal-------------------------------------
1872 //
1873 // If the previous store is to the same address as this load,
1874 // and the value stored was larger than a byte, replace this load
1875 // with the value stored truncated to a byte. If no truncation is
1876 // needed, the replacement is done in LoadNode::Identity().
1877 //
1878 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
1879 Node* mem = in(MemNode::Memory);
1880 Node* value = can_see_stored_value(mem, phase);
1881 if (value && !phase->type(value)->higher_equal(_type))
1882 return new (phase->C) AndINode(value, phase->intcon(0xFF));
1883 // Identity call will handle the case where truncation is not needed.
1884 return LoadNode::Ideal(phase, can_reshape);
1885 }
1887 const Type* LoadUBNode::Value(PhaseTransform *phase) const {
1888 Node* mem = in(MemNode::Memory);
1889 Node* value = can_see_stored_value(mem,phase);
1890 if (value != NULL && value->is_Con() &&
1891 !value->bottom_type()->higher_equal(_type)) {
1892 // If the input to the store does not fit with the load's result type,
1893 // it must be truncated. We can't delay until Ideal call since
1894 // a singleton Value is needed for split_thru_phi optimization.
1895 int con = value->get_int();
1896 return TypeInt::make(con & 0xFF);
1897 }
1898 return LoadNode::Value(phase);
1899 }
1901 //--------------------------LoadUSNode::Ideal-------------------------------------
1902 //
1903 // If the previous store is to the same address as this load,
1904 // and the value stored was larger than a char, replace this load
1905 // with the value stored truncated to a char. If no truncation is
1906 // needed, the replacement is done in LoadNode::Identity().
1907 //
1908 Node *LoadUSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1909 Node* mem = in(MemNode::Memory);
1910 Node* value = can_see_stored_value(mem,phase);
1911 if( value && !phase->type(value)->higher_equal( _type ) )
1912 return new (phase->C) AndINode(value,phase->intcon(0xFFFF));
1913 // Identity call will handle the case where truncation is not needed.
1914 return LoadNode::Ideal(phase, can_reshape);
1915 }
1917 const Type* LoadUSNode::Value(PhaseTransform *phase) const {
1918 Node* mem = in(MemNode::Memory);
1919 Node* value = can_see_stored_value(mem,phase);
1920 if (value != NULL && value->is_Con() &&
1921 !value->bottom_type()->higher_equal(_type)) {
1922 // If the input to the store does not fit with the load's result type,
1923 // it must be truncated. We can't delay until Ideal call since
1924 // a singleton Value is needed for split_thru_phi optimization.
1925 int con = value->get_int();
1926 return TypeInt::make(con & 0xFFFF);
1927 }
1928 return LoadNode::Value(phase);
1929 }
1931 //--------------------------LoadSNode::Ideal--------------------------------------
1932 //
1933 // If the previous store is to the same address as this load,
1934 // and the value stored was larger than a short, replace this load
1935 // with the value stored truncated to a short. If no truncation is
1936 // needed, the replacement is done in LoadNode::Identity().
1937 //
1938 Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1939 Node* mem = in(MemNode::Memory);
1940 Node* value = can_see_stored_value(mem,phase);
1941 if( value && !phase->type(value)->higher_equal( _type ) ) {
1942 Node *result = phase->transform( new (phase->C) LShiftINode(value, phase->intcon(16)) );
1943 return new (phase->C) RShiftINode(result, phase->intcon(16));
1944 }
1945 // Identity call will handle the case where truncation is not needed.
1946 return LoadNode::Ideal(phase, can_reshape);
1947 }
1949 const Type* LoadSNode::Value(PhaseTransform *phase) const {
1950 Node* mem = in(MemNode::Memory);
1951 Node* value = can_see_stored_value(mem,phase);
1952 if (value != NULL && value->is_Con() &&
1953 !value->bottom_type()->higher_equal(_type)) {
1954 // If the input to the store does not fit with the load's result type,
1955 // it must be truncated. We can't delay until Ideal call since
1956 // a singleton Value is needed for split_thru_phi optimization.
1957 int con = value->get_int();
1958 return TypeInt::make((con << 16) >> 16);
1959 }
1960 return LoadNode::Value(phase);
1961 }
1963 //=============================================================================
1964 //----------------------------LoadKlassNode::make------------------------------
1965 // Polymorphic factory method:
1966 Node *LoadKlassNode::make( PhaseGVN& gvn, Node *mem, Node *adr, const TypePtr* at, const TypeKlassPtr *tk ) {
1967 Compile* C = gvn.C;
1968 Node *ctl = NULL;
1969 // sanity check the alias category against the created node type
1970 const TypePtr *adr_type = adr->bottom_type()->isa_ptr();
1971 assert(adr_type != NULL, "expecting TypeKlassPtr");
1972 #ifdef _LP64
1973 if (adr_type->is_ptr_to_narrowklass()) {
1974 assert(UseCompressedKlassPointers, "no compressed klasses");
1975 Node* load_klass = gvn.transform(new (C) LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowklass()));
1976 return new (C) DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr());
1977 }
1978 #endif
1979 assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
1980 return new (C) LoadKlassNode(ctl, mem, adr, at, tk);
1981 }
1983 //------------------------------Value------------------------------------------
1984 const Type *LoadKlassNode::Value( PhaseTransform *phase ) const {
1985 return klass_value_common(phase);
1986 }
1988 const Type *LoadNode::klass_value_common( PhaseTransform *phase ) const {
1989 // Either input is TOP ==> the result is TOP
1990 const Type *t1 = phase->type( in(MemNode::Memory) );
1991 if (t1 == Type::TOP) return Type::TOP;
1992 Node *adr = in(MemNode::Address);
1993 const Type *t2 = phase->type( adr );
1994 if (t2 == Type::TOP) return Type::TOP;
1995 const TypePtr *tp = t2->is_ptr();
1996 if (TypePtr::above_centerline(tp->ptr()) ||
1997 tp->ptr() == TypePtr::Null) return Type::TOP;
1999 // Return a more precise klass, if possible
2000 const TypeInstPtr *tinst = tp->isa_instptr();
2001 if (tinst != NULL) {
2002 ciInstanceKlass* ik = tinst->klass()->as_instance_klass();
2003 int offset = tinst->offset();
2004 if (ik == phase->C->env()->Class_klass()
2005 && (offset == java_lang_Class::klass_offset_in_bytes() ||
2006 offset == java_lang_Class::array_klass_offset_in_bytes())) {
2007 // We are loading a special hidden field from a Class mirror object,
2008 // the field which points to the VM's Klass metaobject.
2009 ciType* t = tinst->java_mirror_type();
2010 // java_mirror_type returns non-null for compile-time Class constants.
2011 if (t != NULL) {
2012 // constant oop => constant klass
2013 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
2014 return TypeKlassPtr::make(ciArrayKlass::make(t));
2015 }
2016 if (!t->is_klass()) {
2017 // a primitive Class (e.g., int.class) has NULL for a klass field
2018 return TypePtr::NULL_PTR;
2019 }
2020 // (Folds up the 1st indirection in aClassConstant.getModifiers().)
2021 return TypeKlassPtr::make(t->as_klass());
2022 }
2023 // non-constant mirror, so we can't tell what's going on
2024 }
2025 if( !ik->is_loaded() )
2026 return _type; // Bail out if not loaded
2027 if (offset == oopDesc::klass_offset_in_bytes()) {
2028 if (tinst->klass_is_exact()) {
2029 return TypeKlassPtr::make(ik);
2030 }
2031 // See if we can become precise: no subklasses and no interface
2032 // (Note: We need to support verified interfaces.)
2033 if (!ik->is_interface() && !ik->has_subklass()) {
2034 //assert(!UseExactTypes, "this code should be useless with exact types");
2035 // Add a dependence; if any subclass added we need to recompile
2036 if (!ik->is_final()) {
2037 // %%% should use stronger assert_unique_concrete_subtype instead
2038 phase->C->dependencies()->assert_leaf_type(ik);
2039 }
2040 // Return precise klass
2041 return TypeKlassPtr::make(ik);
2042 }
2044 // Return root of possible klass
2045 return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/);
2046 }
2047 }
2049 // Check for loading klass from an array
2050 const TypeAryPtr *tary = tp->isa_aryptr();
2051 if( tary != NULL ) {
2052 ciKlass *tary_klass = tary->klass();
2053 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP
2054 && tary->offset() == oopDesc::klass_offset_in_bytes()) {
2055 if (tary->klass_is_exact()) {
2056 return TypeKlassPtr::make(tary_klass);
2057 }
2058 ciArrayKlass *ak = tary->klass()->as_array_klass();
2059 // If the klass is an object array, we defer the question to the
2060 // array component klass.
2061 if( ak->is_obj_array_klass() ) {
2062 assert( ak->is_loaded(), "" );
2063 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass();
2064 if( base_k->is_loaded() && base_k->is_instance_klass() ) {
2065 ciInstanceKlass* ik = base_k->as_instance_klass();
2066 // See if we can become precise: no subklasses and no interface
2067 if (!ik->is_interface() && !ik->has_subklass()) {
2068 //assert(!UseExactTypes, "this code should be useless with exact types");
2069 // Add a dependence; if any subclass added we need to recompile
2070 if (!ik->is_final()) {
2071 phase->C->dependencies()->assert_leaf_type(ik);
2072 }
2073 // Return precise array klass
2074 return TypeKlassPtr::make(ak);
2075 }
2076 }
2077 return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/);
2078 } else { // Found a type-array?
2079 //assert(!UseExactTypes, "this code should be useless with exact types");
2080 assert( ak->is_type_array_klass(), "" );
2081 return TypeKlassPtr::make(ak); // These are always precise
2082 }
2083 }
2084 }
2086 // Check for loading klass from an array klass
2087 const TypeKlassPtr *tkls = tp->isa_klassptr();
2088 if (tkls != NULL && !StressReflectiveCode) {
2089 ciKlass* klass = tkls->klass();
2090 if( !klass->is_loaded() )
2091 return _type; // Bail out if not loaded
2092 if( klass->is_obj_array_klass() &&
2093 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) {
2094 ciKlass* elem = klass->as_obj_array_klass()->element_klass();
2095 // // Always returning precise element type is incorrect,
2096 // // e.g., element type could be object and array may contain strings
2097 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
2099 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
2100 // according to the element type's subclassing.
2101 return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/);
2102 }
2103 if( klass->is_instance_klass() && tkls->klass_is_exact() &&
2104 tkls->offset() == in_bytes(Klass::super_offset())) {
2105 ciKlass* sup = klass->as_instance_klass()->super();
2106 // The field is Klass::_super. Return its (constant) value.
2107 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
2108 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR;
2109 }
2110 }
2112 // Bailout case
2113 return LoadNode::Value(phase);
2114 }
2116 //------------------------------Identity---------------------------------------
2117 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
2118 // Also feed through the klass in Allocate(...klass...)._klass.
2119 Node* LoadKlassNode::Identity( PhaseTransform *phase ) {
2120 return klass_identity_common(phase);
2121 }
2123 Node* LoadNode::klass_identity_common(PhaseTransform *phase ) {
2124 Node* x = LoadNode::Identity(phase);
2125 if (x != this) return x;
2127 // Take apart the address into an oop and and offset.
2128 // Return 'this' if we cannot.
2129 Node* adr = in(MemNode::Address);
2130 intptr_t offset = 0;
2131 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2132 if (base == NULL) return this;
2133 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
2134 if (toop == NULL) return this;
2136 // We can fetch the klass directly through an AllocateNode.
2137 // This works even if the klass is not constant (clone or newArray).
2138 if (offset == oopDesc::klass_offset_in_bytes()) {
2139 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
2140 if (allocated_klass != NULL) {
2141 return allocated_klass;
2142 }
2143 }
2145 // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*.
2146 // Simplify ak.component_mirror.array_klass to plain ak, ak an ArrayKlass.
2147 // See inline_native_Class_query for occurrences of these patterns.
2148 // Java Example: x.getClass().isAssignableFrom(y)
2149 // Java Example: Array.newInstance(x.getClass().getComponentType(), n)
2150 //
2151 // This improves reflective code, often making the Class
2152 // mirror go completely dead. (Current exception: Class
2153 // mirrors may appear in debug info, but we could clean them out by
2154 // introducing a new debug info operator for Klass*.java_mirror).
2155 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass()
2156 && (offset == java_lang_Class::klass_offset_in_bytes() ||
2157 offset == java_lang_Class::array_klass_offset_in_bytes())) {
2158 // We are loading a special hidden field from a Class mirror,
2159 // the field which points to its Klass or ArrayKlass metaobject.
2160 if (base->is_Load()) {
2161 Node* adr2 = base->in(MemNode::Address);
2162 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2163 if (tkls != NULL && !tkls->empty()
2164 && (tkls->klass()->is_instance_klass() ||
2165 tkls->klass()->is_array_klass())
2166 && adr2->is_AddP()
2167 ) {
2168 int mirror_field = in_bytes(Klass::java_mirror_offset());
2169 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
2170 mirror_field = in_bytes(ArrayKlass::component_mirror_offset());
2171 }
2172 if (tkls->offset() == mirror_field) {
2173 return adr2->in(AddPNode::Base);
2174 }
2175 }
2176 }
2177 }
2179 return this;
2180 }
2183 //------------------------------Value------------------------------------------
2184 const Type *LoadNKlassNode::Value( PhaseTransform *phase ) const {
2185 const Type *t = klass_value_common(phase);
2186 if (t == Type::TOP)
2187 return t;
2189 return t->make_narrowklass();
2190 }
2192 //------------------------------Identity---------------------------------------
2193 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
2194 // Also feed through the klass in Allocate(...klass...)._klass.
2195 Node* LoadNKlassNode::Identity( PhaseTransform *phase ) {
2196 Node *x = klass_identity_common(phase);
2198 const Type *t = phase->type( x );
2199 if( t == Type::TOP ) return x;
2200 if( t->isa_narrowklass()) return x;
2201 assert (!t->isa_narrowoop(), "no narrow oop here");
2203 return phase->transform(new (phase->C) EncodePKlassNode(x, t->make_narrowklass()));
2204 }
2206 //------------------------------Value-----------------------------------------
2207 const Type *LoadRangeNode::Value( PhaseTransform *phase ) const {
2208 // Either input is TOP ==> the result is TOP
2209 const Type *t1 = phase->type( in(MemNode::Memory) );
2210 if( t1 == Type::TOP ) return Type::TOP;
2211 Node *adr = in(MemNode::Address);
2212 const Type *t2 = phase->type( adr );
2213 if( t2 == Type::TOP ) return Type::TOP;
2214 const TypePtr *tp = t2->is_ptr();
2215 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
2216 const TypeAryPtr *tap = tp->isa_aryptr();
2217 if( !tap ) return _type;
2218 return tap->size();
2219 }
2221 //-------------------------------Ideal---------------------------------------
2222 // Feed through the length in AllocateArray(...length...)._length.
2223 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2224 Node* p = MemNode::Ideal_common(phase, can_reshape);
2225 if (p) return (p == NodeSentinel) ? NULL : p;
2227 // Take apart the address into an oop and and offset.
2228 // Return 'this' if we cannot.
2229 Node* adr = in(MemNode::Address);
2230 intptr_t offset = 0;
2231 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2232 if (base == NULL) return NULL;
2233 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2234 if (tary == NULL) return NULL;
2236 // We can fetch the length directly through an AllocateArrayNode.
2237 // This works even if the length is not constant (clone or newArray).
2238 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2239 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2240 if (alloc != NULL) {
2241 Node* allocated_length = alloc->Ideal_length();
2242 Node* len = alloc->make_ideal_length(tary, phase);
2243 if (allocated_length != len) {
2244 // New CastII improves on this.
2245 return len;
2246 }
2247 }
2248 }
2250 return NULL;
2251 }
2253 //------------------------------Identity---------------------------------------
2254 // Feed through the length in AllocateArray(...length...)._length.
2255 Node* LoadRangeNode::Identity( PhaseTransform *phase ) {
2256 Node* x = LoadINode::Identity(phase);
2257 if (x != this) return x;
2259 // Take apart the address into an oop and and offset.
2260 // Return 'this' if we cannot.
2261 Node* adr = in(MemNode::Address);
2262 intptr_t offset = 0;
2263 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2264 if (base == NULL) return this;
2265 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2266 if (tary == NULL) return this;
2268 // We can fetch the length directly through an AllocateArrayNode.
2269 // This works even if the length is not constant (clone or newArray).
2270 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2271 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2272 if (alloc != NULL) {
2273 Node* allocated_length = alloc->Ideal_length();
2274 // Do not allow make_ideal_length to allocate a CastII node.
2275 Node* len = alloc->make_ideal_length(tary, phase, false);
2276 if (allocated_length == len) {
2277 // Return allocated_length only if it would not be improved by a CastII.
2278 return allocated_length;
2279 }
2280 }
2281 }
2283 return this;
2285 }
2287 //=============================================================================
2288 //---------------------------StoreNode::make-----------------------------------
2289 // Polymorphic factory method:
2290 StoreNode* StoreNode::make( PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt ) {
2291 Compile* C = gvn.C;
2292 assert( C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2293 ctl != NULL, "raw memory operations should have control edge");
2295 switch (bt) {
2296 case T_BOOLEAN:
2297 case T_BYTE: return new (C) StoreBNode(ctl, mem, adr, adr_type, val);
2298 case T_INT: return new (C) StoreINode(ctl, mem, adr, adr_type, val);
2299 case T_CHAR:
2300 case T_SHORT: return new (C) StoreCNode(ctl, mem, adr, adr_type, val);
2301 case T_LONG: return new (C) StoreLNode(ctl, mem, adr, adr_type, val);
2302 case T_FLOAT: return new (C) StoreFNode(ctl, mem, adr, adr_type, val);
2303 case T_DOUBLE: return new (C) StoreDNode(ctl, mem, adr, adr_type, val);
2304 case T_METADATA:
2305 case T_ADDRESS:
2306 case T_OBJECT:
2307 #ifdef _LP64
2308 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
2309 val = gvn.transform(new (C) EncodePNode(val, val->bottom_type()->make_narrowoop()));
2310 return new (C) StoreNNode(ctl, mem, adr, adr_type, val);
2311 } else if (adr->bottom_type()->is_ptr_to_narrowklass() ||
2312 (UseCompressedKlassPointers && val->bottom_type()->isa_klassptr() &&
2313 adr->bottom_type()->isa_rawptr())) {
2314 val = gvn.transform(new (C) EncodePKlassNode(val, val->bottom_type()->make_narrowklass()));
2315 return new (C) StoreNKlassNode(ctl, mem, adr, adr_type, val);
2316 }
2317 #endif
2318 {
2319 return new (C) StorePNode(ctl, mem, adr, adr_type, val);
2320 }
2321 }
2322 ShouldNotReachHere();
2323 return (StoreNode*)NULL;
2324 }
2326 StoreLNode* StoreLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val) {
2327 bool require_atomic = true;
2328 return new (C) StoreLNode(ctl, mem, adr, adr_type, val, require_atomic);
2329 }
2332 //--------------------------bottom_type----------------------------------------
2333 const Type *StoreNode::bottom_type() const {
2334 return Type::MEMORY;
2335 }
2337 //------------------------------hash-------------------------------------------
2338 uint StoreNode::hash() const {
2339 // unroll addition of interesting fields
2340 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2342 // Since they are not commoned, do not hash them:
2343 return NO_HASH;
2344 }
2346 //------------------------------Ideal------------------------------------------
2347 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
2348 // When a store immediately follows a relevant allocation/initialization,
2349 // try to capture it into the initialization, or hoist it above.
2350 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2351 Node* p = MemNode::Ideal_common(phase, can_reshape);
2352 if (p) return (p == NodeSentinel) ? NULL : p;
2354 Node* mem = in(MemNode::Memory);
2355 Node* address = in(MemNode::Address);
2357 // Back-to-back stores to same address? Fold em up. Generally
2358 // unsafe if I have intervening uses... Also disallowed for StoreCM
2359 // since they must follow each StoreP operation. Redundant StoreCMs
2360 // are eliminated just before matching in final_graph_reshape.
2361 if (mem->is_Store() && mem->in(MemNode::Address)->eqv_uncast(address) &&
2362 mem->Opcode() != Op_StoreCM) {
2363 // Looking at a dead closed cycle of memory?
2364 assert(mem != mem->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
2366 assert(Opcode() == mem->Opcode() ||
2367 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw,
2368 "no mismatched stores, except on raw memory");
2370 if (mem->outcnt() == 1 && // check for intervening uses
2371 mem->as_Store()->memory_size() <= this->memory_size()) {
2372 // If anybody other than 'this' uses 'mem', we cannot fold 'mem' away.
2373 // For example, 'mem' might be the final state at a conditional return.
2374 // Or, 'mem' might be used by some node which is live at the same time
2375 // 'this' is live, which might be unschedulable. So, require exactly
2376 // ONE user, the 'this' store, until such time as we clone 'mem' for
2377 // each of 'mem's uses (thus making the exactly-1-user-rule hold true).
2378 if (can_reshape) { // (%%% is this an anachronism?)
2379 set_req_X(MemNode::Memory, mem->in(MemNode::Memory),
2380 phase->is_IterGVN());
2381 } else {
2382 // It's OK to do this in the parser, since DU info is always accurate,
2383 // and the parser always refers to nodes via SafePointNode maps.
2384 set_req(MemNode::Memory, mem->in(MemNode::Memory));
2385 }
2386 return this;
2387 }
2388 }
2390 // Capture an unaliased, unconditional, simple store into an initializer.
2391 // Or, if it is independent of the allocation, hoist it above the allocation.
2392 if (ReduceFieldZeroing && /*can_reshape &&*/
2393 mem->is_Proj() && mem->in(0)->is_Initialize()) {
2394 InitializeNode* init = mem->in(0)->as_Initialize();
2395 intptr_t offset = init->can_capture_store(this, phase, can_reshape);
2396 if (offset > 0) {
2397 Node* moved = init->capture_store(this, offset, phase, can_reshape);
2398 // If the InitializeNode captured me, it made a raw copy of me,
2399 // and I need to disappear.
2400 if (moved != NULL) {
2401 // %%% hack to ensure that Ideal returns a new node:
2402 mem = MergeMemNode::make(phase->C, mem);
2403 return mem; // fold me away
2404 }
2405 }
2406 }
2408 return NULL; // No further progress
2409 }
2411 //------------------------------Value-----------------------------------------
2412 const Type *StoreNode::Value( PhaseTransform *phase ) const {
2413 // Either input is TOP ==> the result is TOP
2414 const Type *t1 = phase->type( in(MemNode::Memory) );
2415 if( t1 == Type::TOP ) return Type::TOP;
2416 const Type *t2 = phase->type( in(MemNode::Address) );
2417 if( t2 == Type::TOP ) return Type::TOP;
2418 const Type *t3 = phase->type( in(MemNode::ValueIn) );
2419 if( t3 == Type::TOP ) return Type::TOP;
2420 return Type::MEMORY;
2421 }
2423 //------------------------------Identity---------------------------------------
2424 // Remove redundant stores:
2425 // Store(m, p, Load(m, p)) changes to m.
2426 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
2427 Node *StoreNode::Identity( PhaseTransform *phase ) {
2428 Node* mem = in(MemNode::Memory);
2429 Node* adr = in(MemNode::Address);
2430 Node* val = in(MemNode::ValueIn);
2432 // Load then Store? Then the Store is useless
2433 if (val->is_Load() &&
2434 val->in(MemNode::Address)->eqv_uncast(adr) &&
2435 val->in(MemNode::Memory )->eqv_uncast(mem) &&
2436 val->as_Load()->store_Opcode() == Opcode()) {
2437 return mem;
2438 }
2440 // Two stores in a row of the same value?
2441 if (mem->is_Store() &&
2442 mem->in(MemNode::Address)->eqv_uncast(adr) &&
2443 mem->in(MemNode::ValueIn)->eqv_uncast(val) &&
2444 mem->Opcode() == Opcode()) {
2445 return mem;
2446 }
2448 // Store of zero anywhere into a freshly-allocated object?
2449 // Then the store is useless.
2450 // (It must already have been captured by the InitializeNode.)
2451 if (ReduceFieldZeroing && phase->type(val)->is_zero_type()) {
2452 // a newly allocated object is already all-zeroes everywhere
2453 if (mem->is_Proj() && mem->in(0)->is_Allocate()) {
2454 return mem;
2455 }
2457 // the store may also apply to zero-bits in an earlier object
2458 Node* prev_mem = find_previous_store(phase);
2459 // Steps (a), (b): Walk past independent stores to find an exact match.
2460 if (prev_mem != NULL) {
2461 Node* prev_val = can_see_stored_value(prev_mem, phase);
2462 if (prev_val != NULL && phase->eqv(prev_val, val)) {
2463 // prev_val and val might differ by a cast; it would be good
2464 // to keep the more informative of the two.
2465 return mem;
2466 }
2467 }
2468 }
2470 return this;
2471 }
2473 //------------------------------match_edge-------------------------------------
2474 // Do we Match on this edge index or not? Match only memory & value
2475 uint StoreNode::match_edge(uint idx) const {
2476 return idx == MemNode::Address || idx == MemNode::ValueIn;
2477 }
2479 //------------------------------cmp--------------------------------------------
2480 // Do not common stores up together. They generally have to be split
2481 // back up anyways, so do not bother.
2482 uint StoreNode::cmp( const Node &n ) const {
2483 return (&n == this); // Always fail except on self
2484 }
2486 //------------------------------Ideal_masked_input-----------------------------
2487 // Check for a useless mask before a partial-word store
2488 // (StoreB ... (AndI valIn conIa) )
2489 // If (conIa & mask == mask) this simplifies to
2490 // (StoreB ... (valIn) )
2491 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
2492 Node *val = in(MemNode::ValueIn);
2493 if( val->Opcode() == Op_AndI ) {
2494 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2495 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
2496 set_req(MemNode::ValueIn, val->in(1));
2497 return this;
2498 }
2499 }
2500 return NULL;
2501 }
2504 //------------------------------Ideal_sign_extended_input----------------------
2505 // Check for useless sign-extension before a partial-word store
2506 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) )
2507 // If (conIL == conIR && conIR <= num_bits) this simplifies to
2508 // (StoreB ... (valIn) )
2509 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) {
2510 Node *val = in(MemNode::ValueIn);
2511 if( val->Opcode() == Op_RShiftI ) {
2512 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2513 if( t && t->is_con() && (t->get_con() <= num_bits) ) {
2514 Node *shl = val->in(1);
2515 if( shl->Opcode() == Op_LShiftI ) {
2516 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int();
2517 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) {
2518 set_req(MemNode::ValueIn, shl->in(1));
2519 return this;
2520 }
2521 }
2522 }
2523 }
2524 return NULL;
2525 }
2527 //------------------------------value_never_loaded-----------------------------------
2528 // Determine whether there are any possible loads of the value stored.
2529 // For simplicity, we actually check if there are any loads from the
2530 // address stored to, not just for loads of the value stored by this node.
2531 //
2532 bool StoreNode::value_never_loaded( PhaseTransform *phase) const {
2533 Node *adr = in(Address);
2534 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
2535 if (adr_oop == NULL)
2536 return false;
2537 if (!adr_oop->is_known_instance_field())
2538 return false; // if not a distinct instance, there may be aliases of the address
2539 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
2540 Node *use = adr->fast_out(i);
2541 int opc = use->Opcode();
2542 if (use->is_Load() || use->is_LoadStore()) {
2543 return false;
2544 }
2545 }
2546 return true;
2547 }
2549 //=============================================================================
2550 //------------------------------Ideal------------------------------------------
2551 // If the store is from an AND mask that leaves the low bits untouched, then
2552 // we can skip the AND operation. If the store is from a sign-extension
2553 // (a left shift, then right shift) we can skip both.
2554 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
2555 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
2556 if( progress != NULL ) return progress;
2558 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
2559 if( progress != NULL ) return progress;
2561 // Finally check the default case
2562 return StoreNode::Ideal(phase, can_reshape);
2563 }
2565 //=============================================================================
2566 //------------------------------Ideal------------------------------------------
2567 // If the store is from an AND mask that leaves the low bits untouched, then
2568 // we can skip the AND operation
2569 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
2570 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
2571 if( progress != NULL ) return progress;
2573 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
2574 if( progress != NULL ) return progress;
2576 // Finally check the default case
2577 return StoreNode::Ideal(phase, can_reshape);
2578 }
2580 //=============================================================================
2581 //------------------------------Identity---------------------------------------
2582 Node *StoreCMNode::Identity( PhaseTransform *phase ) {
2583 // No need to card mark when storing a null ptr
2584 Node* my_store = in(MemNode::OopStore);
2585 if (my_store->is_Store()) {
2586 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) );
2587 if( t1 == TypePtr::NULL_PTR ) {
2588 return in(MemNode::Memory);
2589 }
2590 }
2591 return this;
2592 }
2594 //=============================================================================
2595 //------------------------------Ideal---------------------------------------
2596 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){
2597 Node* progress = StoreNode::Ideal(phase, can_reshape);
2598 if (progress != NULL) return progress;
2600 Node* my_store = in(MemNode::OopStore);
2601 if (my_store->is_MergeMem()) {
2602 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx());
2603 set_req(MemNode::OopStore, mem);
2604 return this;
2605 }
2607 return NULL;
2608 }
2610 //------------------------------Value-----------------------------------------
2611 const Type *StoreCMNode::Value( PhaseTransform *phase ) const {
2612 // Either input is TOP ==> the result is TOP
2613 const Type *t = phase->type( in(MemNode::Memory) );
2614 if( t == Type::TOP ) return Type::TOP;
2615 t = phase->type( in(MemNode::Address) );
2616 if( t == Type::TOP ) return Type::TOP;
2617 t = phase->type( in(MemNode::ValueIn) );
2618 if( t == Type::TOP ) return Type::TOP;
2619 // If extra input is TOP ==> the result is TOP
2620 t = phase->type( in(MemNode::OopStore) );
2621 if( t == Type::TOP ) return Type::TOP;
2623 return StoreNode::Value( phase );
2624 }
2627 //=============================================================================
2628 //----------------------------------SCMemProjNode------------------------------
2629 const Type * SCMemProjNode::Value( PhaseTransform *phase ) const
2630 {
2631 return bottom_type();
2632 }
2634 //=============================================================================
2635 //----------------------------------LoadStoreNode------------------------------
2636 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required )
2637 : Node(required),
2638 _type(rt),
2639 _adr_type(at)
2640 {
2641 init_req(MemNode::Control, c );
2642 init_req(MemNode::Memory , mem);
2643 init_req(MemNode::Address, adr);
2644 init_req(MemNode::ValueIn, val);
2645 init_class_id(Class_LoadStore);
2646 }
2648 uint LoadStoreNode::ideal_reg() const {
2649 return _type->ideal_reg();
2650 }
2652 bool LoadStoreNode::result_not_used() const {
2653 for( DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++ ) {
2654 Node *x = fast_out(i);
2655 if (x->Opcode() == Op_SCMemProj) continue;
2656 return false;
2657 }
2658 return true;
2659 }
2661 uint LoadStoreNode::size_of() const { return sizeof(*this); }
2663 //=============================================================================
2664 //----------------------------------LoadStoreConditionalNode--------------------
2665 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, NULL, TypeInt::BOOL, 5) {
2666 init_req(ExpectedIn, ex );
2667 }
2669 //=============================================================================
2670 //-------------------------------adr_type--------------------------------------
2671 // Do we Match on this edge index or not? Do not match memory
2672 const TypePtr* ClearArrayNode::adr_type() const {
2673 Node *adr = in(3);
2674 return MemNode::calculate_adr_type(adr->bottom_type());
2675 }
2677 //------------------------------match_edge-------------------------------------
2678 // Do we Match on this edge index or not? Do not match memory
2679 uint ClearArrayNode::match_edge(uint idx) const {
2680 return idx > 1;
2681 }
2683 //------------------------------Identity---------------------------------------
2684 // Clearing a zero length array does nothing
2685 Node *ClearArrayNode::Identity( PhaseTransform *phase ) {
2686 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
2687 }
2689 //------------------------------Idealize---------------------------------------
2690 // Clearing a short array is faster with stores
2691 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape){
2692 const int unit = BytesPerLong;
2693 const TypeX* t = phase->type(in(2))->isa_intptr_t();
2694 if (!t) return NULL;
2695 if (!t->is_con()) return NULL;
2696 intptr_t raw_count = t->get_con();
2697 intptr_t size = raw_count;
2698 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
2699 // Clearing nothing uses the Identity call.
2700 // Negative clears are possible on dead ClearArrays
2701 // (see jck test stmt114.stmt11402.val).
2702 if (size <= 0 || size % unit != 0) return NULL;
2703 intptr_t count = size / unit;
2704 // Length too long; use fast hardware clear
2705 if (size > Matcher::init_array_short_size) return NULL;
2706 Node *mem = in(1);
2707 if( phase->type(mem)==Type::TOP ) return NULL;
2708 Node *adr = in(3);
2709 const Type* at = phase->type(adr);
2710 if( at==Type::TOP ) return NULL;
2711 const TypePtr* atp = at->isa_ptr();
2712 // adjust atp to be the correct array element address type
2713 if (atp == NULL) atp = TypePtr::BOTTOM;
2714 else atp = atp->add_offset(Type::OffsetBot);
2715 // Get base for derived pointer purposes
2716 if( adr->Opcode() != Op_AddP ) Unimplemented();
2717 Node *base = adr->in(1);
2719 Node *zero = phase->makecon(TypeLong::ZERO);
2720 Node *off = phase->MakeConX(BytesPerLong);
2721 mem = new (phase->C) StoreLNode(in(0),mem,adr,atp,zero);
2722 count--;
2723 while( count-- ) {
2724 mem = phase->transform(mem);
2725 adr = phase->transform(new (phase->C) AddPNode(base,adr,off));
2726 mem = new (phase->C) StoreLNode(in(0),mem,adr,atp,zero);
2727 }
2728 return mem;
2729 }
2731 //----------------------------step_through----------------------------------
2732 // Return allocation input memory edge if it is different instance
2733 // or itself if it is the one we are looking for.
2734 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) {
2735 Node* n = *np;
2736 assert(n->is_ClearArray(), "sanity");
2737 intptr_t offset;
2738 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
2739 // This method is called only before Allocate nodes are expanded during
2740 // macro nodes expansion. Before that ClearArray nodes are only generated
2741 // in LibraryCallKit::generate_arraycopy() which follows allocations.
2742 assert(alloc != NULL, "should have allocation");
2743 if (alloc->_idx == instance_id) {
2744 // Can not bypass initialization of the instance we are looking for.
2745 return false;
2746 }
2747 // Otherwise skip it.
2748 InitializeNode* init = alloc->initialization();
2749 if (init != NULL)
2750 *np = init->in(TypeFunc::Memory);
2751 else
2752 *np = alloc->in(TypeFunc::Memory);
2753 return true;
2754 }
2756 //----------------------------clear_memory-------------------------------------
2757 // Generate code to initialize object storage to zero.
2758 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2759 intptr_t start_offset,
2760 Node* end_offset,
2761 PhaseGVN* phase) {
2762 Compile* C = phase->C;
2763 intptr_t offset = start_offset;
2765 int unit = BytesPerLong;
2766 if ((offset % unit) != 0) {
2767 Node* adr = new (C) AddPNode(dest, dest, phase->MakeConX(offset));
2768 adr = phase->transform(adr);
2769 const TypePtr* atp = TypeRawPtr::BOTTOM;
2770 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT);
2771 mem = phase->transform(mem);
2772 offset += BytesPerInt;
2773 }
2774 assert((offset % unit) == 0, "");
2776 // Initialize the remaining stuff, if any, with a ClearArray.
2777 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase);
2778 }
2780 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2781 Node* start_offset,
2782 Node* end_offset,
2783 PhaseGVN* phase) {
2784 if (start_offset == end_offset) {
2785 // nothing to do
2786 return mem;
2787 }
2789 Compile* C = phase->C;
2790 int unit = BytesPerLong;
2791 Node* zbase = start_offset;
2792 Node* zend = end_offset;
2794 // Scale to the unit required by the CPU:
2795 if (!Matcher::init_array_count_is_in_bytes) {
2796 Node* shift = phase->intcon(exact_log2(unit));
2797 zbase = phase->transform( new(C) URShiftXNode(zbase, shift) );
2798 zend = phase->transform( new(C) URShiftXNode(zend, shift) );
2799 }
2801 // Bulk clear double-words
2802 Node* zsize = phase->transform( new(C) SubXNode(zend, zbase) );
2803 Node* adr = phase->transform( new(C) AddPNode(dest, dest, start_offset) );
2804 mem = new (C) ClearArrayNode(ctl, mem, zsize, adr);
2805 return phase->transform(mem);
2806 }
2808 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2809 intptr_t start_offset,
2810 intptr_t end_offset,
2811 PhaseGVN* phase) {
2812 if (start_offset == end_offset) {
2813 // nothing to do
2814 return mem;
2815 }
2817 Compile* C = phase->C;
2818 assert((end_offset % BytesPerInt) == 0, "odd end offset");
2819 intptr_t done_offset = end_offset;
2820 if ((done_offset % BytesPerLong) != 0) {
2821 done_offset -= BytesPerInt;
2822 }
2823 if (done_offset > start_offset) {
2824 mem = clear_memory(ctl, mem, dest,
2825 start_offset, phase->MakeConX(done_offset), phase);
2826 }
2827 if (done_offset < end_offset) { // emit the final 32-bit store
2828 Node* adr = new (C) AddPNode(dest, dest, phase->MakeConX(done_offset));
2829 adr = phase->transform(adr);
2830 const TypePtr* atp = TypeRawPtr::BOTTOM;
2831 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT);
2832 mem = phase->transform(mem);
2833 done_offset += BytesPerInt;
2834 }
2835 assert(done_offset == end_offset, "");
2836 return mem;
2837 }
2839 //=============================================================================
2840 // Do not match memory edge.
2841 uint StrIntrinsicNode::match_edge(uint idx) const {
2842 return idx == 2 || idx == 3;
2843 }
2845 //------------------------------Ideal------------------------------------------
2846 // Return a node which is more "ideal" than the current node. Strip out
2847 // control copies
2848 Node *StrIntrinsicNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2849 if (remove_dead_region(phase, can_reshape)) return this;
2850 // Don't bother trying to transform a dead node
2851 if (in(0) && in(0)->is_top()) return NULL;
2853 if (can_reshape) {
2854 Node* mem = phase->transform(in(MemNode::Memory));
2855 // If transformed to a MergeMem, get the desired slice
2856 uint alias_idx = phase->C->get_alias_index(adr_type());
2857 mem = mem->is_MergeMem() ? mem->as_MergeMem()->memory_at(alias_idx) : mem;
2858 if (mem != in(MemNode::Memory)) {
2859 set_req(MemNode::Memory, mem);
2860 return this;
2861 }
2862 }
2863 return NULL;
2864 }
2866 //------------------------------Value------------------------------------------
2867 const Type *StrIntrinsicNode::Value( PhaseTransform *phase ) const {
2868 if (in(0) && phase->type(in(0)) == Type::TOP) return Type::TOP;
2869 return bottom_type();
2870 }
2872 //=============================================================================
2873 //------------------------------match_edge-------------------------------------
2874 // Do not match memory edge
2875 uint EncodeISOArrayNode::match_edge(uint idx) const {
2876 return idx == 2 || idx == 3; // EncodeISOArray src (Binary dst len)
2877 }
2879 //------------------------------Ideal------------------------------------------
2880 // Return a node which is more "ideal" than the current node. Strip out
2881 // control copies
2882 Node *EncodeISOArrayNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2883 return remove_dead_region(phase, can_reshape) ? this : NULL;
2884 }
2886 //------------------------------Value------------------------------------------
2887 const Type *EncodeISOArrayNode::Value(PhaseTransform *phase) const {
2888 if (in(0) && phase->type(in(0)) == Type::TOP) return Type::TOP;
2889 return bottom_type();
2890 }
2892 //=============================================================================
2893 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
2894 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)),
2895 _adr_type(C->get_adr_type(alias_idx))
2896 {
2897 init_class_id(Class_MemBar);
2898 Node* top = C->top();
2899 init_req(TypeFunc::I_O,top);
2900 init_req(TypeFunc::FramePtr,top);
2901 init_req(TypeFunc::ReturnAdr,top);
2902 if (precedent != NULL)
2903 init_req(TypeFunc::Parms, precedent);
2904 }
2906 //------------------------------cmp--------------------------------------------
2907 uint MemBarNode::hash() const { return NO_HASH; }
2908 uint MemBarNode::cmp( const Node &n ) const {
2909 return (&n == this); // Always fail except on self
2910 }
2912 //------------------------------make-------------------------------------------
2913 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
2914 switch (opcode) {
2915 case Op_MemBarAcquire: return new(C) MemBarAcquireNode(C, atp, pn);
2916 case Op_MemBarRelease: return new(C) MemBarReleaseNode(C, atp, pn);
2917 case Op_MemBarAcquireLock: return new(C) MemBarAcquireLockNode(C, atp, pn);
2918 case Op_MemBarReleaseLock: return new(C) MemBarReleaseLockNode(C, atp, pn);
2919 case Op_MemBarVolatile: return new(C) MemBarVolatileNode(C, atp, pn);
2920 case Op_MemBarCPUOrder: return new(C) MemBarCPUOrderNode(C, atp, pn);
2921 case Op_Initialize: return new(C) InitializeNode(C, atp, pn);
2922 case Op_MemBarStoreStore: return new(C) MemBarStoreStoreNode(C, atp, pn);
2923 default: ShouldNotReachHere(); return NULL;
2924 }
2925 }
2927 //------------------------------Ideal------------------------------------------
2928 // Return a node which is more "ideal" than the current node. Strip out
2929 // control copies
2930 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2931 if (remove_dead_region(phase, can_reshape)) return this;
2932 // Don't bother trying to transform a dead node
2933 if (in(0) && in(0)->is_top()) {
2934 return NULL;
2935 }
2937 // Eliminate volatile MemBars for scalar replaced objects.
2938 if (can_reshape && req() == (Precedent+1)) {
2939 bool eliminate = false;
2940 int opc = Opcode();
2941 if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) {
2942 // Volatile field loads and stores.
2943 Node* my_mem = in(MemBarNode::Precedent);
2944 // The MembarAquire may keep an unused LoadNode alive through the Precedent edge
2945 if ((my_mem != NULL) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) {
2946 // if the Precedent is a decodeN and its input (a Load) is used at more than one place,
2947 // replace this Precedent (decodeN) with the Load instead.
2948 if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1)) {
2949 Node* load_node = my_mem->in(1);
2950 set_req(MemBarNode::Precedent, load_node);
2951 phase->is_IterGVN()->_worklist.push(my_mem);
2952 my_mem = load_node;
2953 } else {
2954 assert(my_mem->unique_out() == this, "sanity");
2955 del_req(Precedent);
2956 phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later
2957 my_mem = NULL;
2958 }
2959 }
2960 if (my_mem != NULL && my_mem->is_Mem()) {
2961 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
2962 // Check for scalar replaced object reference.
2963 if( t_oop != NULL && t_oop->is_known_instance_field() &&
2964 t_oop->offset() != Type::OffsetBot &&
2965 t_oop->offset() != Type::OffsetTop) {
2966 eliminate = true;
2967 }
2968 }
2969 } else if (opc == Op_MemBarRelease) {
2970 // Final field stores.
2971 Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent), phase);
2972 if ((alloc != NULL) && alloc->is_Allocate() &&
2973 alloc->as_Allocate()->_is_non_escaping) {
2974 // The allocated object does not escape.
2975 eliminate = true;
2976 }
2977 }
2978 if (eliminate) {
2979 // Replace MemBar projections by its inputs.
2980 PhaseIterGVN* igvn = phase->is_IterGVN();
2981 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
2982 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
2983 // Must return either the original node (now dead) or a new node
2984 // (Do not return a top here, since that would break the uniqueness of top.)
2985 return new (phase->C) ConINode(TypeInt::ZERO);
2986 }
2987 }
2988 return NULL;
2989 }
2991 //------------------------------Value------------------------------------------
2992 const Type *MemBarNode::Value( PhaseTransform *phase ) const {
2993 if( !in(0) ) return Type::TOP;
2994 if( phase->type(in(0)) == Type::TOP )
2995 return Type::TOP;
2996 return TypeTuple::MEMBAR;
2997 }
2999 //------------------------------match------------------------------------------
3000 // Construct projections for memory.
3001 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) {
3002 switch (proj->_con) {
3003 case TypeFunc::Control:
3004 case TypeFunc::Memory:
3005 return new (m->C) MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
3006 }
3007 ShouldNotReachHere();
3008 return NULL;
3009 }
3011 //===========================InitializeNode====================================
3012 // SUMMARY:
3013 // This node acts as a memory barrier on raw memory, after some raw stores.
3014 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
3015 // The Initialize can 'capture' suitably constrained stores as raw inits.
3016 // It can coalesce related raw stores into larger units (called 'tiles').
3017 // It can avoid zeroing new storage for memory units which have raw inits.
3018 // At macro-expansion, it is marked 'complete', and does not optimize further.
3019 //
3020 // EXAMPLE:
3021 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
3022 // ctl = incoming control; mem* = incoming memory
3023 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
3024 // First allocate uninitialized memory and fill in the header:
3025 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
3026 // ctl := alloc.Control; mem* := alloc.Memory*
3027 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
3028 // Then initialize to zero the non-header parts of the raw memory block:
3029 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
3030 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
3031 // After the initialize node executes, the object is ready for service:
3032 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
3033 // Suppose its body is immediately initialized as {1,2}:
3034 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3035 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3036 // mem.SLICE(#short[*]) := store2
3037 //
3038 // DETAILS:
3039 // An InitializeNode collects and isolates object initialization after
3040 // an AllocateNode and before the next possible safepoint. As a
3041 // memory barrier (MemBarNode), it keeps critical stores from drifting
3042 // down past any safepoint or any publication of the allocation.
3043 // Before this barrier, a newly-allocated object may have uninitialized bits.
3044 // After this barrier, it may be treated as a real oop, and GC is allowed.
3045 //
3046 // The semantics of the InitializeNode include an implicit zeroing of
3047 // the new object from object header to the end of the object.
3048 // (The object header and end are determined by the AllocateNode.)
3049 //
3050 // Certain stores may be added as direct inputs to the InitializeNode.
3051 // These stores must update raw memory, and they must be to addresses
3052 // derived from the raw address produced by AllocateNode, and with
3053 // a constant offset. They must be ordered by increasing offset.
3054 // The first one is at in(RawStores), the last at in(req()-1).
3055 // Unlike most memory operations, they are not linked in a chain,
3056 // but are displayed in parallel as users of the rawmem output of
3057 // the allocation.
3058 //
3059 // (See comments in InitializeNode::capture_store, which continue
3060 // the example given above.)
3061 //
3062 // When the associated Allocate is macro-expanded, the InitializeNode
3063 // may be rewritten to optimize collected stores. A ClearArrayNode
3064 // may also be created at that point to represent any required zeroing.
3065 // The InitializeNode is then marked 'complete', prohibiting further
3066 // capturing of nearby memory operations.
3067 //
3068 // During macro-expansion, all captured initializations which store
3069 // constant values of 32 bits or smaller are coalesced (if advantageous)
3070 // into larger 'tiles' 32 or 64 bits. This allows an object to be
3071 // initialized in fewer memory operations. Memory words which are
3072 // covered by neither tiles nor non-constant stores are pre-zeroed
3073 // by explicit stores of zero. (The code shape happens to do all
3074 // zeroing first, then all other stores, with both sequences occurring
3075 // in order of ascending offsets.)
3076 //
3077 // Alternatively, code may be inserted between an AllocateNode and its
3078 // InitializeNode, to perform arbitrary initialization of the new object.
3079 // E.g., the object copying intrinsics insert complex data transfers here.
3080 // The initialization must then be marked as 'complete' disable the
3081 // built-in zeroing semantics and the collection of initializing stores.
3082 //
3083 // While an InitializeNode is incomplete, reads from the memory state
3084 // produced by it are optimizable if they match the control edge and
3085 // new oop address associated with the allocation/initialization.
3086 // They return a stored value (if the offset matches) or else zero.
3087 // A write to the memory state, if it matches control and address,
3088 // and if it is to a constant offset, may be 'captured' by the
3089 // InitializeNode. It is cloned as a raw memory operation and rewired
3090 // inside the initialization, to the raw oop produced by the allocation.
3091 // Operations on addresses which are provably distinct (e.g., to
3092 // other AllocateNodes) are allowed to bypass the initialization.
3093 //
3094 // The effect of all this is to consolidate object initialization
3095 // (both arrays and non-arrays, both piecewise and bulk) into a
3096 // single location, where it can be optimized as a unit.
3097 //
3098 // Only stores with an offset less than TrackedInitializationLimit words
3099 // will be considered for capture by an InitializeNode. This puts a
3100 // reasonable limit on the complexity of optimized initializations.
3102 //---------------------------InitializeNode------------------------------------
3103 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
3104 : _is_complete(Incomplete), _does_not_escape(false),
3105 MemBarNode(C, adr_type, rawoop)
3106 {
3107 init_class_id(Class_Initialize);
3109 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
3110 assert(in(RawAddress) == rawoop, "proper init");
3111 // Note: allocation() can be NULL, for secondary initialization barriers
3112 }
3114 // Since this node is not matched, it will be processed by the
3115 // register allocator. Declare that there are no constraints
3116 // on the allocation of the RawAddress edge.
3117 const RegMask &InitializeNode::in_RegMask(uint idx) const {
3118 // This edge should be set to top, by the set_complete. But be conservative.
3119 if (idx == InitializeNode::RawAddress)
3120 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
3121 return RegMask::Empty;
3122 }
3124 Node* InitializeNode::memory(uint alias_idx) {
3125 Node* mem = in(Memory);
3126 if (mem->is_MergeMem()) {
3127 return mem->as_MergeMem()->memory_at(alias_idx);
3128 } else {
3129 // incoming raw memory is not split
3130 return mem;
3131 }
3132 }
3134 bool InitializeNode::is_non_zero() {
3135 if (is_complete()) return false;
3136 remove_extra_zeroes();
3137 return (req() > RawStores);
3138 }
3140 void InitializeNode::set_complete(PhaseGVN* phase) {
3141 assert(!is_complete(), "caller responsibility");
3142 _is_complete = Complete;
3144 // After this node is complete, it contains a bunch of
3145 // raw-memory initializations. There is no need for
3146 // it to have anything to do with non-raw memory effects.
3147 // Therefore, tell all non-raw users to re-optimize themselves,
3148 // after skipping the memory effects of this initialization.
3149 PhaseIterGVN* igvn = phase->is_IterGVN();
3150 if (igvn) igvn->add_users_to_worklist(this);
3151 }
3153 // convenience function
3154 // return false if the init contains any stores already
3155 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
3156 InitializeNode* init = initialization();
3157 if (init == NULL || init->is_complete()) return false;
3158 init->remove_extra_zeroes();
3159 // for now, if this allocation has already collected any inits, bail:
3160 if (init->is_non_zero()) return false;
3161 init->set_complete(phase);
3162 return true;
3163 }
3165 void InitializeNode::remove_extra_zeroes() {
3166 if (req() == RawStores) return;
3167 Node* zmem = zero_memory();
3168 uint fill = RawStores;
3169 for (uint i = fill; i < req(); i++) {
3170 Node* n = in(i);
3171 if (n->is_top() || n == zmem) continue; // skip
3172 if (fill < i) set_req(fill, n); // compact
3173 ++fill;
3174 }
3175 // delete any empty spaces created:
3176 while (fill < req()) {
3177 del_req(fill);
3178 }
3179 }
3181 // Helper for remembering which stores go with which offsets.
3182 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) {
3183 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
3184 intptr_t offset = -1;
3185 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
3186 phase, offset);
3187 if (base == NULL) return -1; // something is dead,
3188 if (offset < 0) return -1; // dead, dead
3189 return offset;
3190 }
3192 // Helper for proving that an initialization expression is
3193 // "simple enough" to be folded into an object initialization.
3194 // Attempts to prove that a store's initial value 'n' can be captured
3195 // within the initialization without creating a vicious cycle, such as:
3196 // { Foo p = new Foo(); p.next = p; }
3197 // True for constants and parameters and small combinations thereof.
3198 bool InitializeNode::detect_init_independence(Node* n, int& count) {
3199 if (n == NULL) return true; // (can this really happen?)
3200 if (n->is_Proj()) n = n->in(0);
3201 if (n == this) return false; // found a cycle
3202 if (n->is_Con()) return true;
3203 if (n->is_Start()) return true; // params, etc., are OK
3204 if (n->is_Root()) return true; // even better
3206 Node* ctl = n->in(0);
3207 if (ctl != NULL && !ctl->is_top()) {
3208 if (ctl->is_Proj()) ctl = ctl->in(0);
3209 if (ctl == this) return false;
3211 // If we already know that the enclosing memory op is pinned right after
3212 // the init, then any control flow that the store has picked up
3213 // must have preceded the init, or else be equal to the init.
3214 // Even after loop optimizations (which might change control edges)
3215 // a store is never pinned *before* the availability of its inputs.
3216 if (!MemNode::all_controls_dominate(n, this))
3217 return false; // failed to prove a good control
3218 }
3220 // Check data edges for possible dependencies on 'this'.
3221 if ((count += 1) > 20) return false; // complexity limit
3222 for (uint i = 1; i < n->req(); i++) {
3223 Node* m = n->in(i);
3224 if (m == NULL || m == n || m->is_top()) continue;
3225 uint first_i = n->find_edge(m);
3226 if (i != first_i) continue; // process duplicate edge just once
3227 if (!detect_init_independence(m, count)) {
3228 return false;
3229 }
3230 }
3232 return true;
3233 }
3235 // Here are all the checks a Store must pass before it can be moved into
3236 // an initialization. Returns zero if a check fails.
3237 // On success, returns the (constant) offset to which the store applies,
3238 // within the initialized memory.
3239 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase, bool can_reshape) {
3240 const int FAIL = 0;
3241 if (st->req() != MemNode::ValueIn + 1)
3242 return FAIL; // an inscrutable StoreNode (card mark?)
3243 Node* ctl = st->in(MemNode::Control);
3244 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this))
3245 return FAIL; // must be unconditional after the initialization
3246 Node* mem = st->in(MemNode::Memory);
3247 if (!(mem->is_Proj() && mem->in(0) == this))
3248 return FAIL; // must not be preceded by other stores
3249 Node* adr = st->in(MemNode::Address);
3250 intptr_t offset;
3251 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
3252 if (alloc == NULL)
3253 return FAIL; // inscrutable address
3254 if (alloc != allocation())
3255 return FAIL; // wrong allocation! (store needs to float up)
3256 Node* val = st->in(MemNode::ValueIn);
3257 int complexity_count = 0;
3258 if (!detect_init_independence(val, complexity_count))
3259 return FAIL; // stored value must be 'simple enough'
3261 // The Store can be captured only if nothing after the allocation
3262 // and before the Store is using the memory location that the store
3263 // overwrites.
3264 bool failed = false;
3265 // If is_complete_with_arraycopy() is true the shape of the graph is
3266 // well defined and is safe so no need for extra checks.
3267 if (!is_complete_with_arraycopy()) {
3268 // We are going to look at each use of the memory state following
3269 // the allocation to make sure nothing reads the memory that the
3270 // Store writes.
3271 const TypePtr* t_adr = phase->type(adr)->isa_ptr();
3272 int alias_idx = phase->C->get_alias_index(t_adr);
3273 ResourceMark rm;
3274 Unique_Node_List mems;
3275 mems.push(mem);
3276 Node* unique_merge = NULL;
3277 for (uint next = 0; next < mems.size(); ++next) {
3278 Node *m = mems.at(next);
3279 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
3280 Node *n = m->fast_out(j);
3281 if (n->outcnt() == 0) {
3282 continue;
3283 }
3284 if (n == st) {
3285 continue;
3286 } else if (n->in(0) != NULL && n->in(0) != ctl) {
3287 // If the control of this use is different from the control
3288 // of the Store which is right after the InitializeNode then
3289 // this node cannot be between the InitializeNode and the
3290 // Store.
3291 continue;
3292 } else if (n->is_MergeMem()) {
3293 if (n->as_MergeMem()->memory_at(alias_idx) == m) {
3294 // We can hit a MergeMemNode (that will likely go away
3295 // later) that is a direct use of the memory state
3296 // following the InitializeNode on the same slice as the
3297 // store node that we'd like to capture. We need to check
3298 // the uses of the MergeMemNode.
3299 mems.push(n);
3300 }
3301 } else if (n->is_Mem()) {
3302 Node* other_adr = n->in(MemNode::Address);
3303 if (other_adr == adr) {
3304 failed = true;
3305 break;
3306 } else {
3307 const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr();
3308 if (other_t_adr != NULL) {
3309 int other_alias_idx = phase->C->get_alias_index(other_t_adr);
3310 if (other_alias_idx == alias_idx) {
3311 // A load from the same memory slice as the store right
3312 // after the InitializeNode. We check the control of the
3313 // object/array that is loaded from. If it's the same as
3314 // the store control then we cannot capture the store.
3315 assert(!n->is_Store(), "2 stores to same slice on same control?");
3316 Node* base = other_adr;
3317 assert(base->is_AddP(), err_msg_res("should be addp but is %s", base->Name()));
3318 base = base->in(AddPNode::Base);
3319 if (base != NULL) {
3320 base = base->uncast();
3321 if (base->is_Proj() && base->in(0) == alloc) {
3322 failed = true;
3323 break;
3324 }
3325 }
3326 }
3327 }
3328 }
3329 } else {
3330 failed = true;
3331 break;
3332 }
3333 }
3334 }
3335 }
3336 if (failed) {
3337 if (!can_reshape) {
3338 // We decided we couldn't capture the store during parsing. We
3339 // should try again during the next IGVN once the graph is
3340 // cleaner.
3341 phase->C->record_for_igvn(st);
3342 }
3343 return FAIL;
3344 }
3346 return offset; // success
3347 }
3349 // Find the captured store in(i) which corresponds to the range
3350 // [start..start+size) in the initialized object.
3351 // If there is one, return its index i. If there isn't, return the
3352 // negative of the index where it should be inserted.
3353 // Return 0 if the queried range overlaps an initialization boundary
3354 // or if dead code is encountered.
3355 // If size_in_bytes is zero, do not bother with overlap checks.
3356 int InitializeNode::captured_store_insertion_point(intptr_t start,
3357 int size_in_bytes,
3358 PhaseTransform* phase) {
3359 const int FAIL = 0, MAX_STORE = BytesPerLong;
3361 if (is_complete())
3362 return FAIL; // arraycopy got here first; punt
3364 assert(allocation() != NULL, "must be present");
3366 // no negatives, no header fields:
3367 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
3369 // after a certain size, we bail out on tracking all the stores:
3370 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3371 if (start >= ti_limit) return FAIL;
3373 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
3374 if (i >= limit) return -(int)i; // not found; here is where to put it
3376 Node* st = in(i);
3377 intptr_t st_off = get_store_offset(st, phase);
3378 if (st_off < 0) {
3379 if (st != zero_memory()) {
3380 return FAIL; // bail out if there is dead garbage
3381 }
3382 } else if (st_off > start) {
3383 // ...we are done, since stores are ordered
3384 if (st_off < start + size_in_bytes) {
3385 return FAIL; // the next store overlaps
3386 }
3387 return -(int)i; // not found; here is where to put it
3388 } else if (st_off < start) {
3389 if (size_in_bytes != 0 &&
3390 start < st_off + MAX_STORE &&
3391 start < st_off + st->as_Store()->memory_size()) {
3392 return FAIL; // the previous store overlaps
3393 }
3394 } else {
3395 if (size_in_bytes != 0 &&
3396 st->as_Store()->memory_size() != size_in_bytes) {
3397 return FAIL; // mismatched store size
3398 }
3399 return i;
3400 }
3402 ++i;
3403 }
3404 }
3406 // Look for a captured store which initializes at the offset 'start'
3407 // with the given size. If there is no such store, and no other
3408 // initialization interferes, then return zero_memory (the memory
3409 // projection of the AllocateNode).
3410 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
3411 PhaseTransform* phase) {
3412 assert(stores_are_sane(phase), "");
3413 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3414 if (i == 0) {
3415 return NULL; // something is dead
3416 } else if (i < 0) {
3417 return zero_memory(); // just primordial zero bits here
3418 } else {
3419 Node* st = in(i); // here is the store at this position
3420 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
3421 return st;
3422 }
3423 }
3425 // Create, as a raw pointer, an address within my new object at 'offset'.
3426 Node* InitializeNode::make_raw_address(intptr_t offset,
3427 PhaseTransform* phase) {
3428 Node* addr = in(RawAddress);
3429 if (offset != 0) {
3430 Compile* C = phase->C;
3431 addr = phase->transform( new (C) AddPNode(C->top(), addr,
3432 phase->MakeConX(offset)) );
3433 }
3434 return addr;
3435 }
3437 // Clone the given store, converting it into a raw store
3438 // initializing a field or element of my new object.
3439 // Caller is responsible for retiring the original store,
3440 // with subsume_node or the like.
3441 //
3442 // From the example above InitializeNode::InitializeNode,
3443 // here are the old stores to be captured:
3444 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3445 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3446 //
3447 // Here is the changed code; note the extra edges on init:
3448 // alloc = (Allocate ...)
3449 // rawoop = alloc.RawAddress
3450 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
3451 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
3452 // init = (Initialize alloc.Control alloc.Memory rawoop
3453 // rawstore1 rawstore2)
3454 //
3455 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
3456 PhaseTransform* phase, bool can_reshape) {
3457 assert(stores_are_sane(phase), "");
3459 if (start < 0) return NULL;
3460 assert(can_capture_store(st, phase, can_reshape) == start, "sanity");
3462 Compile* C = phase->C;
3463 int size_in_bytes = st->memory_size();
3464 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3465 if (i == 0) return NULL; // bail out
3466 Node* prev_mem = NULL; // raw memory for the captured store
3467 if (i > 0) {
3468 prev_mem = in(i); // there is a pre-existing store under this one
3469 set_req(i, C->top()); // temporarily disconnect it
3470 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
3471 } else {
3472 i = -i; // no pre-existing store
3473 prev_mem = zero_memory(); // a slice of the newly allocated object
3474 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
3475 set_req(--i, C->top()); // reuse this edge; it has been folded away
3476 else
3477 ins_req(i, C->top()); // build a new edge
3478 }
3479 Node* new_st = st->clone();
3480 new_st->set_req(MemNode::Control, in(Control));
3481 new_st->set_req(MemNode::Memory, prev_mem);
3482 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
3483 new_st = phase->transform(new_st);
3485 // At this point, new_st might have swallowed a pre-existing store
3486 // at the same offset, or perhaps new_st might have disappeared,
3487 // if it redundantly stored the same value (or zero to fresh memory).
3489 // In any case, wire it in:
3490 set_req(i, new_st);
3492 // The caller may now kill the old guy.
3493 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
3494 assert(check_st == new_st || check_st == NULL, "must be findable");
3495 assert(!is_complete(), "");
3496 return new_st;
3497 }
3499 static bool store_constant(jlong* tiles, int num_tiles,
3500 intptr_t st_off, int st_size,
3501 jlong con) {
3502 if ((st_off & (st_size-1)) != 0)
3503 return false; // strange store offset (assume size==2**N)
3504 address addr = (address)tiles + st_off;
3505 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
3506 switch (st_size) {
3507 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
3508 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
3509 case sizeof(jint): *(jint*) addr = (jint) con; break;
3510 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
3511 default: return false; // strange store size (detect size!=2**N here)
3512 }
3513 return true; // return success to caller
3514 }
3516 // Coalesce subword constants into int constants and possibly
3517 // into long constants. The goal, if the CPU permits,
3518 // is to initialize the object with a small number of 64-bit tiles.
3519 // Also, convert floating-point constants to bit patterns.
3520 // Non-constants are not relevant to this pass.
3521 //
3522 // In terms of the running example on InitializeNode::InitializeNode
3523 // and InitializeNode::capture_store, here is the transformation
3524 // of rawstore1 and rawstore2 into rawstore12:
3525 // alloc = (Allocate ...)
3526 // rawoop = alloc.RawAddress
3527 // tile12 = 0x00010002
3528 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
3529 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
3530 //
3531 void
3532 InitializeNode::coalesce_subword_stores(intptr_t header_size,
3533 Node* size_in_bytes,
3534 PhaseGVN* phase) {
3535 Compile* C = phase->C;
3537 assert(stores_are_sane(phase), "");
3538 // Note: After this pass, they are not completely sane,
3539 // since there may be some overlaps.
3541 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
3543 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3544 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
3545 size_limit = MIN2(size_limit, ti_limit);
3546 size_limit = align_size_up(size_limit, BytesPerLong);
3547 int num_tiles = size_limit / BytesPerLong;
3549 // allocate space for the tile map:
3550 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
3551 jlong tiles_buf[small_len];
3552 Node* nodes_buf[small_len];
3553 jlong inits_buf[small_len];
3554 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
3555 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3556 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
3557 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
3558 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
3559 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3560 // tiles: exact bitwise model of all primitive constants
3561 // nodes: last constant-storing node subsumed into the tiles model
3562 // inits: which bytes (in each tile) are touched by any initializations
3564 //// Pass A: Fill in the tile model with any relevant stores.
3566 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
3567 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
3568 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
3569 Node* zmem = zero_memory(); // initially zero memory state
3570 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3571 Node* st = in(i);
3572 intptr_t st_off = get_store_offset(st, phase);
3574 // Figure out the store's offset and constant value:
3575 if (st_off < header_size) continue; //skip (ignore header)
3576 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
3577 int st_size = st->as_Store()->memory_size();
3578 if (st_off + st_size > size_limit) break;
3580 // Record which bytes are touched, whether by constant or not.
3581 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
3582 continue; // skip (strange store size)
3584 const Type* val = phase->type(st->in(MemNode::ValueIn));
3585 if (!val->singleton()) continue; //skip (non-con store)
3586 BasicType type = val->basic_type();
3588 jlong con = 0;
3589 switch (type) {
3590 case T_INT: con = val->is_int()->get_con(); break;
3591 case T_LONG: con = val->is_long()->get_con(); break;
3592 case T_FLOAT: con = jint_cast(val->getf()); break;
3593 case T_DOUBLE: con = jlong_cast(val->getd()); break;
3594 default: continue; //skip (odd store type)
3595 }
3597 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
3598 st->Opcode() == Op_StoreL) {
3599 continue; // This StoreL is already optimal.
3600 }
3602 // Store down the constant.
3603 store_constant(tiles, num_tiles, st_off, st_size, con);
3605 intptr_t j = st_off >> LogBytesPerLong;
3607 if (type == T_INT && st_size == BytesPerInt
3608 && (st_off & BytesPerInt) == BytesPerInt) {
3609 jlong lcon = tiles[j];
3610 if (!Matcher::isSimpleConstant64(lcon) &&
3611 st->Opcode() == Op_StoreI) {
3612 // This StoreI is already optimal by itself.
3613 jint* intcon = (jint*) &tiles[j];
3614 intcon[1] = 0; // undo the store_constant()
3616 // If the previous store is also optimal by itself, back up and
3617 // undo the action of the previous loop iteration... if we can.
3618 // But if we can't, just let the previous half take care of itself.
3619 st = nodes[j];
3620 st_off -= BytesPerInt;
3621 con = intcon[0];
3622 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) {
3623 assert(st_off >= header_size, "still ignoring header");
3624 assert(get_store_offset(st, phase) == st_off, "must be");
3625 assert(in(i-1) == zmem, "must be");
3626 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
3627 assert(con == tcon->is_int()->get_con(), "must be");
3628 // Undo the effects of the previous loop trip, which swallowed st:
3629 intcon[0] = 0; // undo store_constant()
3630 set_req(i-1, st); // undo set_req(i, zmem)
3631 nodes[j] = NULL; // undo nodes[j] = st
3632 --old_subword; // undo ++old_subword
3633 }
3634 continue; // This StoreI is already optimal.
3635 }
3636 }
3638 // This store is not needed.
3639 set_req(i, zmem);
3640 nodes[j] = st; // record for the moment
3641 if (st_size < BytesPerLong) // something has changed
3642 ++old_subword; // includes int/float, but who's counting...
3643 else ++old_long;
3644 }
3646 if ((old_subword + old_long) == 0)
3647 return; // nothing more to do
3649 //// Pass B: Convert any non-zero tiles into optimal constant stores.
3650 // Be sure to insert them before overlapping non-constant stores.
3651 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
3652 for (int j = 0; j < num_tiles; j++) {
3653 jlong con = tiles[j];
3654 jlong init = inits[j];
3655 if (con == 0) continue;
3656 jint con0, con1; // split the constant, address-wise
3657 jint init0, init1; // split the init map, address-wise
3658 { union { jlong con; jint intcon[2]; } u;
3659 u.con = con;
3660 con0 = u.intcon[0];
3661 con1 = u.intcon[1];
3662 u.con = init;
3663 init0 = u.intcon[0];
3664 init1 = u.intcon[1];
3665 }
3667 Node* old = nodes[j];
3668 assert(old != NULL, "need the prior store");
3669 intptr_t offset = (j * BytesPerLong);
3671 bool split = !Matcher::isSimpleConstant64(con);
3673 if (offset < header_size) {
3674 assert(offset + BytesPerInt >= header_size, "second int counts");
3675 assert(*(jint*)&tiles[j] == 0, "junk in header");
3676 split = true; // only the second word counts
3677 // Example: int a[] = { 42 ... }
3678 } else if (con0 == 0 && init0 == -1) {
3679 split = true; // first word is covered by full inits
3680 // Example: int a[] = { ... foo(), 42 ... }
3681 } else if (con1 == 0 && init1 == -1) {
3682 split = true; // second word is covered by full inits
3683 // Example: int a[] = { ... 42, foo() ... }
3684 }
3686 // Here's a case where init0 is neither 0 nor -1:
3687 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
3688 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
3689 // In this case the tile is not split; it is (jlong)42.
3690 // The big tile is stored down, and then the foo() value is inserted.
3691 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
3693 Node* ctl = old->in(MemNode::Control);
3694 Node* adr = make_raw_address(offset, phase);
3695 const TypePtr* atp = TypeRawPtr::BOTTOM;
3697 // One or two coalesced stores to plop down.
3698 Node* st[2];
3699 intptr_t off[2];
3700 int nst = 0;
3701 if (!split) {
3702 ++new_long;
3703 off[nst] = offset;
3704 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3705 phase->longcon(con), T_LONG);
3706 } else {
3707 // Omit either if it is a zero.
3708 if (con0 != 0) {
3709 ++new_int;
3710 off[nst] = offset;
3711 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3712 phase->intcon(con0), T_INT);
3713 }
3714 if (con1 != 0) {
3715 ++new_int;
3716 offset += BytesPerInt;
3717 adr = make_raw_address(offset, phase);
3718 off[nst] = offset;
3719 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3720 phase->intcon(con1), T_INT);
3721 }
3722 }
3724 // Insert second store first, then the first before the second.
3725 // Insert each one just before any overlapping non-constant stores.
3726 while (nst > 0) {
3727 Node* st1 = st[--nst];
3728 C->copy_node_notes_to(st1, old);
3729 st1 = phase->transform(st1);
3730 offset = off[nst];
3731 assert(offset >= header_size, "do not smash header");
3732 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
3733 guarantee(ins_idx != 0, "must re-insert constant store");
3734 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
3735 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
3736 set_req(--ins_idx, st1);
3737 else
3738 ins_req(ins_idx, st1);
3739 }
3740 }
3742 if (PrintCompilation && WizardMode)
3743 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
3744 old_subword, old_long, new_int, new_long);
3745 if (C->log() != NULL)
3746 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
3747 old_subword, old_long, new_int, new_long);
3749 // Clean up any remaining occurrences of zmem:
3750 remove_extra_zeroes();
3751 }
3753 // Explore forward from in(start) to find the first fully initialized
3754 // word, and return its offset. Skip groups of subword stores which
3755 // together initialize full words. If in(start) is itself part of a
3756 // fully initialized word, return the offset of in(start). If there
3757 // are no following full-word stores, or if something is fishy, return
3758 // a negative value.
3759 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
3760 int int_map = 0;
3761 intptr_t int_map_off = 0;
3762 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
3764 for (uint i = start, limit = req(); i < limit; i++) {
3765 Node* st = in(i);
3767 intptr_t st_off = get_store_offset(st, phase);
3768 if (st_off < 0) break; // return conservative answer
3770 int st_size = st->as_Store()->memory_size();
3771 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
3772 return st_off; // we found a complete word init
3773 }
3775 // update the map:
3777 intptr_t this_int_off = align_size_down(st_off, BytesPerInt);
3778 if (this_int_off != int_map_off) {
3779 // reset the map:
3780 int_map = 0;
3781 int_map_off = this_int_off;
3782 }
3784 int subword_off = st_off - this_int_off;
3785 int_map |= right_n_bits(st_size) << subword_off;
3786 if ((int_map & FULL_MAP) == FULL_MAP) {
3787 return this_int_off; // we found a complete word init
3788 }
3790 // Did this store hit or cross the word boundary?
3791 intptr_t next_int_off = align_size_down(st_off + st_size, BytesPerInt);
3792 if (next_int_off == this_int_off + BytesPerInt) {
3793 // We passed the current int, without fully initializing it.
3794 int_map_off = next_int_off;
3795 int_map >>= BytesPerInt;
3796 } else if (next_int_off > this_int_off + BytesPerInt) {
3797 // We passed the current and next int.
3798 return this_int_off + BytesPerInt;
3799 }
3800 }
3802 return -1;
3803 }
3806 // Called when the associated AllocateNode is expanded into CFG.
3807 // At this point, we may perform additional optimizations.
3808 // Linearize the stores by ascending offset, to make memory
3809 // activity as coherent as possible.
3810 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
3811 intptr_t header_size,
3812 Node* size_in_bytes,
3813 PhaseGVN* phase) {
3814 assert(!is_complete(), "not already complete");
3815 assert(stores_are_sane(phase), "");
3816 assert(allocation() != NULL, "must be present");
3818 remove_extra_zeroes();
3820 if (ReduceFieldZeroing || ReduceBulkZeroing)
3821 // reduce instruction count for common initialization patterns
3822 coalesce_subword_stores(header_size, size_in_bytes, phase);
3824 Node* zmem = zero_memory(); // initially zero memory state
3825 Node* inits = zmem; // accumulating a linearized chain of inits
3826 #ifdef ASSERT
3827 intptr_t first_offset = allocation()->minimum_header_size();
3828 intptr_t last_init_off = first_offset; // previous init offset
3829 intptr_t last_init_end = first_offset; // previous init offset+size
3830 intptr_t last_tile_end = first_offset; // previous tile offset+size
3831 #endif
3832 intptr_t zeroes_done = header_size;
3834 bool do_zeroing = true; // we might give up if inits are very sparse
3835 int big_init_gaps = 0; // how many large gaps have we seen?
3837 if (ZeroTLAB) do_zeroing = false;
3838 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
3840 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3841 Node* st = in(i);
3842 intptr_t st_off = get_store_offset(st, phase);
3843 if (st_off < 0)
3844 break; // unknown junk in the inits
3845 if (st->in(MemNode::Memory) != zmem)
3846 break; // complicated store chains somehow in list
3848 int st_size = st->as_Store()->memory_size();
3849 intptr_t next_init_off = st_off + st_size;
3851 if (do_zeroing && zeroes_done < next_init_off) {
3852 // See if this store needs a zero before it or under it.
3853 intptr_t zeroes_needed = st_off;
3855 if (st_size < BytesPerInt) {
3856 // Look for subword stores which only partially initialize words.
3857 // If we find some, we must lay down some word-level zeroes first,
3858 // underneath the subword stores.
3859 //
3860 // Examples:
3861 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
3862 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
3863 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
3864 //
3865 // Note: coalesce_subword_stores may have already done this,
3866 // if it was prompted by constant non-zero subword initializers.
3867 // But this case can still arise with non-constant stores.
3869 intptr_t next_full_store = find_next_fullword_store(i, phase);
3871 // In the examples above:
3872 // in(i) p q r s x y z
3873 // st_off 12 13 14 15 12 13 14
3874 // st_size 1 1 1 1 1 1 1
3875 // next_full_s. 12 16 16 16 16 16 16
3876 // z's_done 12 16 16 16 12 16 12
3877 // z's_needed 12 16 16 16 16 16 16
3878 // zsize 0 0 0 0 4 0 4
3879 if (next_full_store < 0) {
3880 // Conservative tack: Zero to end of current word.
3881 zeroes_needed = align_size_up(zeroes_needed, BytesPerInt);
3882 } else {
3883 // Zero to beginning of next fully initialized word.
3884 // Or, don't zero at all, if we are already in that word.
3885 assert(next_full_store >= zeroes_needed, "must go forward");
3886 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
3887 zeroes_needed = next_full_store;
3888 }
3889 }
3891 if (zeroes_needed > zeroes_done) {
3892 intptr_t zsize = zeroes_needed - zeroes_done;
3893 // Do some incremental zeroing on rawmem, in parallel with inits.
3894 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3895 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3896 zeroes_done, zeroes_needed,
3897 phase);
3898 zeroes_done = zeroes_needed;
3899 if (zsize > Matcher::init_array_short_size && ++big_init_gaps > 2)
3900 do_zeroing = false; // leave the hole, next time
3901 }
3902 }
3904 // Collect the store and move on:
3905 st->set_req(MemNode::Memory, inits);
3906 inits = st; // put it on the linearized chain
3907 set_req(i, zmem); // unhook from previous position
3909 if (zeroes_done == st_off)
3910 zeroes_done = next_init_off;
3912 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
3914 #ifdef ASSERT
3915 // Various order invariants. Weaker than stores_are_sane because
3916 // a large constant tile can be filled in by smaller non-constant stores.
3917 assert(st_off >= last_init_off, "inits do not reverse");
3918 last_init_off = st_off;
3919 const Type* val = NULL;
3920 if (st_size >= BytesPerInt &&
3921 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
3922 (int)val->basic_type() < (int)T_OBJECT) {
3923 assert(st_off >= last_tile_end, "tiles do not overlap");
3924 assert(st_off >= last_init_end, "tiles do not overwrite inits");
3925 last_tile_end = MAX2(last_tile_end, next_init_off);
3926 } else {
3927 intptr_t st_tile_end = align_size_up(next_init_off, BytesPerLong);
3928 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
3929 assert(st_off >= last_init_end, "inits do not overlap");
3930 last_init_end = next_init_off; // it's a non-tile
3931 }
3932 #endif //ASSERT
3933 }
3935 remove_extra_zeroes(); // clear out all the zmems left over
3936 add_req(inits);
3938 if (!ZeroTLAB) {
3939 // If anything remains to be zeroed, zero it all now.
3940 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3941 // if it is the last unused 4 bytes of an instance, forget about it
3942 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
3943 if (zeroes_done + BytesPerLong >= size_limit) {
3944 assert(allocation() != NULL, "");
3945 if (allocation()->Opcode() == Op_Allocate) {
3946 Node* klass_node = allocation()->in(AllocateNode::KlassNode);
3947 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass();
3948 if (zeroes_done == k->layout_helper())
3949 zeroes_done = size_limit;
3950 }
3951 }
3952 if (zeroes_done < size_limit) {
3953 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3954 zeroes_done, size_in_bytes, phase);
3955 }
3956 }
3958 set_complete(phase);
3959 return rawmem;
3960 }
3963 #ifdef ASSERT
3964 bool InitializeNode::stores_are_sane(PhaseTransform* phase) {
3965 if (is_complete())
3966 return true; // stores could be anything at this point
3967 assert(allocation() != NULL, "must be present");
3968 intptr_t last_off = allocation()->minimum_header_size();
3969 for (uint i = InitializeNode::RawStores; i < req(); i++) {
3970 Node* st = in(i);
3971 intptr_t st_off = get_store_offset(st, phase);
3972 if (st_off < 0) continue; // ignore dead garbage
3973 if (last_off > st_off) {
3974 tty->print_cr("*** bad store offset at %d: %d > %d", i, last_off, st_off);
3975 this->dump(2);
3976 assert(false, "ascending store offsets");
3977 return false;
3978 }
3979 last_off = st_off + st->as_Store()->memory_size();
3980 }
3981 return true;
3982 }
3983 #endif //ASSERT
3988 //============================MergeMemNode=====================================
3989 //
3990 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
3991 // contributing store or call operations. Each contributor provides the memory
3992 // state for a particular "alias type" (see Compile::alias_type). For example,
3993 // if a MergeMem has an input X for alias category #6, then any memory reference
3994 // to alias category #6 may use X as its memory state input, as an exact equivalent
3995 // to using the MergeMem as a whole.
3996 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
3997 //
3998 // (Here, the <N> notation gives the index of the relevant adr_type.)
3999 //
4000 // In one special case (and more cases in the future), alias categories overlap.
4001 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
4002 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
4003 // it is exactly equivalent to that state W:
4004 // MergeMem(<Bot>: W) <==> W
4005 //
4006 // Usually, the merge has more than one input. In that case, where inputs
4007 // overlap (i.e., one is Bot), the narrower alias type determines the memory
4008 // state for that type, and the wider alias type (Bot) fills in everywhere else:
4009 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
4010 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
4011 //
4012 // A merge can take a "wide" memory state as one of its narrow inputs.
4013 // This simply means that the merge observes out only the relevant parts of
4014 // the wide input. That is, wide memory states arriving at narrow merge inputs
4015 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
4016 //
4017 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
4018 // and that memory slices "leak through":
4019 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
4020 //
4021 // But, in such a cascade, repeated memory slices can "block the leak":
4022 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
4023 //
4024 // In the last example, Y is not part of the combined memory state of the
4025 // outermost MergeMem. The system must, of course, prevent unschedulable
4026 // memory states from arising, so you can be sure that the state Y is somehow
4027 // a precursor to state Y'.
4028 //
4029 //
4030 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
4031 // of each MergeMemNode array are exactly the numerical alias indexes, including
4032 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
4033 // Compile::alias_type (and kin) produce and manage these indexes.
4034 //
4035 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
4036 // (Note that this provides quick access to the top node inside MergeMem methods,
4037 // without the need to reach out via TLS to Compile::current.)
4038 //
4039 // As a consequence of what was just described, a MergeMem that represents a full
4040 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
4041 // containing all alias categories.
4042 //
4043 // MergeMem nodes never (?) have control inputs, so in(0) is NULL.
4044 //
4045 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
4046 // a memory state for the alias type <N>, or else the top node, meaning that
4047 // there is no particular input for that alias type. Note that the length of
4048 // a MergeMem is variable, and may be extended at any time to accommodate new
4049 // memory states at larger alias indexes. When merges grow, they are of course
4050 // filled with "top" in the unused in() positions.
4051 //
4052 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
4053 // (Top was chosen because it works smoothly with passes like GCM.)
4054 //
4055 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
4056 // the type of random VM bits like TLS references.) Since it is always the
4057 // first non-Bot memory slice, some low-level loops use it to initialize an
4058 // index variable: for (i = AliasIdxRaw; i < req(); i++).
4059 //
4060 //
4061 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
4062 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
4063 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
4064 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
4065 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
4066 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
4067 //
4068 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
4069 // really that different from the other memory inputs. An abbreviation called
4070 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
4071 //
4072 //
4073 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
4074 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
4075 // that "emerges though" the base memory will be marked as excluding the alias types
4076 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
4077 //
4078 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
4079 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
4080 //
4081 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
4082 // (It is currently unimplemented.) As you can see, the resulting merge is
4083 // actually a disjoint union of memory states, rather than an overlay.
4084 //
4086 //------------------------------MergeMemNode-----------------------------------
4087 Node* MergeMemNode::make_empty_memory() {
4088 Node* empty_memory = (Node*) Compile::current()->top();
4089 assert(empty_memory->is_top(), "correct sentinel identity");
4090 return empty_memory;
4091 }
4093 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
4094 init_class_id(Class_MergeMem);
4095 // all inputs are nullified in Node::Node(int)
4096 // set_input(0, NULL); // no control input
4098 // Initialize the edges uniformly to top, for starters.
4099 Node* empty_mem = make_empty_memory();
4100 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
4101 init_req(i,empty_mem);
4102 }
4103 assert(empty_memory() == empty_mem, "");
4105 if( new_base != NULL && new_base->is_MergeMem() ) {
4106 MergeMemNode* mdef = new_base->as_MergeMem();
4107 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
4108 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
4109 mms.set_memory(mms.memory2());
4110 }
4111 assert(base_memory() == mdef->base_memory(), "");
4112 } else {
4113 set_base_memory(new_base);
4114 }
4115 }
4117 // Make a new, untransformed MergeMem with the same base as 'mem'.
4118 // If mem is itself a MergeMem, populate the result with the same edges.
4119 MergeMemNode* MergeMemNode::make(Compile* C, Node* mem) {
4120 return new(C) MergeMemNode(mem);
4121 }
4123 //------------------------------cmp--------------------------------------------
4124 uint MergeMemNode::hash() const { return NO_HASH; }
4125 uint MergeMemNode::cmp( const Node &n ) const {
4126 return (&n == this); // Always fail except on self
4127 }
4129 //------------------------------Identity---------------------------------------
4130 Node* MergeMemNode::Identity(PhaseTransform *phase) {
4131 // Identity if this merge point does not record any interesting memory
4132 // disambiguations.
4133 Node* base_mem = base_memory();
4134 Node* empty_mem = empty_memory();
4135 if (base_mem != empty_mem) { // Memory path is not dead?
4136 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4137 Node* mem = in(i);
4138 if (mem != empty_mem && mem != base_mem) {
4139 return this; // Many memory splits; no change
4140 }
4141 }
4142 }
4143 return base_mem; // No memory splits; ID on the one true input
4144 }
4146 //------------------------------Ideal------------------------------------------
4147 // This method is invoked recursively on chains of MergeMem nodes
4148 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4149 // Remove chain'd MergeMems
4150 //
4151 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
4152 // relative to the "in(Bot)". Since we are patching both at the same time,
4153 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
4154 // but rewrite each "in(i)" relative to the new "in(Bot)".
4155 Node *progress = NULL;
4158 Node* old_base = base_memory();
4159 Node* empty_mem = empty_memory();
4160 if (old_base == empty_mem)
4161 return NULL; // Dead memory path.
4163 MergeMemNode* old_mbase;
4164 if (old_base != NULL && old_base->is_MergeMem())
4165 old_mbase = old_base->as_MergeMem();
4166 else
4167 old_mbase = NULL;
4168 Node* new_base = old_base;
4170 // simplify stacked MergeMems in base memory
4171 if (old_mbase) new_base = old_mbase->base_memory();
4173 // the base memory might contribute new slices beyond my req()
4174 if (old_mbase) grow_to_match(old_mbase);
4176 // Look carefully at the base node if it is a phi.
4177 PhiNode* phi_base;
4178 if (new_base != NULL && new_base->is_Phi())
4179 phi_base = new_base->as_Phi();
4180 else
4181 phi_base = NULL;
4183 Node* phi_reg = NULL;
4184 uint phi_len = (uint)-1;
4185 if (phi_base != NULL && !phi_base->is_copy()) {
4186 // do not examine phi if degraded to a copy
4187 phi_reg = phi_base->region();
4188 phi_len = phi_base->req();
4189 // see if the phi is unfinished
4190 for (uint i = 1; i < phi_len; i++) {
4191 if (phi_base->in(i) == NULL) {
4192 // incomplete phi; do not look at it yet!
4193 phi_reg = NULL;
4194 phi_len = (uint)-1;
4195 break;
4196 }
4197 }
4198 }
4200 // Note: We do not call verify_sparse on entry, because inputs
4201 // can normalize to the base_memory via subsume_node or similar
4202 // mechanisms. This method repairs that damage.
4204 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
4206 // Look at each slice.
4207 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4208 Node* old_in = in(i);
4209 // calculate the old memory value
4210 Node* old_mem = old_in;
4211 if (old_mem == empty_mem) old_mem = old_base;
4212 assert(old_mem == memory_at(i), "");
4214 // maybe update (reslice) the old memory value
4216 // simplify stacked MergeMems
4217 Node* new_mem = old_mem;
4218 MergeMemNode* old_mmem;
4219 if (old_mem != NULL && old_mem->is_MergeMem())
4220 old_mmem = old_mem->as_MergeMem();
4221 else
4222 old_mmem = NULL;
4223 if (old_mmem == this) {
4224 // This can happen if loops break up and safepoints disappear.
4225 // A merge of BotPtr (default) with a RawPtr memory derived from a
4226 // safepoint can be rewritten to a merge of the same BotPtr with
4227 // the BotPtr phi coming into the loop. If that phi disappears
4228 // also, we can end up with a self-loop of the mergemem.
4229 // In general, if loops degenerate and memory effects disappear,
4230 // a mergemem can be left looking at itself. This simply means
4231 // that the mergemem's default should be used, since there is
4232 // no longer any apparent effect on this slice.
4233 // Note: If a memory slice is a MergeMem cycle, it is unreachable
4234 // from start. Update the input to TOP.
4235 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
4236 }
4237 else if (old_mmem != NULL) {
4238 new_mem = old_mmem->memory_at(i);
4239 }
4240 // else preceding memory was not a MergeMem
4242 // replace equivalent phis (unfortunately, they do not GVN together)
4243 if (new_mem != NULL && new_mem != new_base &&
4244 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) {
4245 if (new_mem->is_Phi()) {
4246 PhiNode* phi_mem = new_mem->as_Phi();
4247 for (uint i = 1; i < phi_len; i++) {
4248 if (phi_base->in(i) != phi_mem->in(i)) {
4249 phi_mem = NULL;
4250 break;
4251 }
4252 }
4253 if (phi_mem != NULL) {
4254 // equivalent phi nodes; revert to the def
4255 new_mem = new_base;
4256 }
4257 }
4258 }
4260 // maybe store down a new value
4261 Node* new_in = new_mem;
4262 if (new_in == new_base) new_in = empty_mem;
4264 if (new_in != old_in) {
4265 // Warning: Do not combine this "if" with the previous "if"
4266 // A memory slice might have be be rewritten even if it is semantically
4267 // unchanged, if the base_memory value has changed.
4268 set_req(i, new_in);
4269 progress = this; // Report progress
4270 }
4271 }
4273 if (new_base != old_base) {
4274 set_req(Compile::AliasIdxBot, new_base);
4275 // Don't use set_base_memory(new_base), because we need to update du.
4276 assert(base_memory() == new_base, "");
4277 progress = this;
4278 }
4280 if( base_memory() == this ) {
4281 // a self cycle indicates this memory path is dead
4282 set_req(Compile::AliasIdxBot, empty_mem);
4283 }
4285 // Resolve external cycles by calling Ideal on a MergeMem base_memory
4286 // Recursion must occur after the self cycle check above
4287 if( base_memory()->is_MergeMem() ) {
4288 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
4289 Node *m = phase->transform(new_mbase); // Rollup any cycles
4290 if( m != NULL && (m->is_top() ||
4291 m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem) ) {
4292 // propagate rollup of dead cycle to self
4293 set_req(Compile::AliasIdxBot, empty_mem);
4294 }
4295 }
4297 if( base_memory() == empty_mem ) {
4298 progress = this;
4299 // Cut inputs during Parse phase only.
4300 // During Optimize phase a dead MergeMem node will be subsumed by Top.
4301 if( !can_reshape ) {
4302 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4303 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
4304 }
4305 }
4306 }
4308 if( !progress && base_memory()->is_Phi() && can_reshape ) {
4309 // Check if PhiNode::Ideal's "Split phis through memory merges"
4310 // transform should be attempted. Look for this->phi->this cycle.
4311 uint merge_width = req();
4312 if (merge_width > Compile::AliasIdxRaw) {
4313 PhiNode* phi = base_memory()->as_Phi();
4314 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
4315 if (phi->in(i) == this) {
4316 phase->is_IterGVN()->_worklist.push(phi);
4317 break;
4318 }
4319 }
4320 }
4321 }
4323 assert(progress || verify_sparse(), "please, no dups of base");
4324 return progress;
4325 }
4327 //-------------------------set_base_memory-------------------------------------
4328 void MergeMemNode::set_base_memory(Node *new_base) {
4329 Node* empty_mem = empty_memory();
4330 set_req(Compile::AliasIdxBot, new_base);
4331 assert(memory_at(req()) == new_base, "must set default memory");
4332 // Clear out other occurrences of new_base:
4333 if (new_base != empty_mem) {
4334 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4335 if (in(i) == new_base) set_req(i, empty_mem);
4336 }
4337 }
4338 }
4340 //------------------------------out_RegMask------------------------------------
4341 const RegMask &MergeMemNode::out_RegMask() const {
4342 return RegMask::Empty;
4343 }
4345 //------------------------------dump_spec--------------------------------------
4346 #ifndef PRODUCT
4347 void MergeMemNode::dump_spec(outputStream *st) const {
4348 st->print(" {");
4349 Node* base_mem = base_memory();
4350 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
4351 Node* mem = memory_at(i);
4352 if (mem == base_mem) { st->print(" -"); continue; }
4353 st->print( " N%d:", mem->_idx );
4354 Compile::current()->get_adr_type(i)->dump_on(st);
4355 }
4356 st->print(" }");
4357 }
4358 #endif // !PRODUCT
4361 #ifdef ASSERT
4362 static bool might_be_same(Node* a, Node* b) {
4363 if (a == b) return true;
4364 if (!(a->is_Phi() || b->is_Phi())) return false;
4365 // phis shift around during optimization
4366 return true; // pretty stupid...
4367 }
4369 // verify a narrow slice (either incoming or outgoing)
4370 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
4371 if (!VerifyAliases) return; // don't bother to verify unless requested
4372 if (is_error_reported()) return; // muzzle asserts when debugging an error
4373 if (Node::in_dump()) return; // muzzle asserts when printing
4374 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
4375 assert(n != NULL, "");
4376 // Elide intervening MergeMem's
4377 while (n->is_MergeMem()) {
4378 n = n->as_MergeMem()->memory_at(alias_idx);
4379 }
4380 Compile* C = Compile::current();
4381 const TypePtr* n_adr_type = n->adr_type();
4382 if (n == m->empty_memory()) {
4383 // Implicit copy of base_memory()
4384 } else if (n_adr_type != TypePtr::BOTTOM) {
4385 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type");
4386 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
4387 } else {
4388 // A few places like make_runtime_call "know" that VM calls are narrow,
4389 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
4390 bool expected_wide_mem = false;
4391 if (n == m->base_memory()) {
4392 expected_wide_mem = true;
4393 } else if (alias_idx == Compile::AliasIdxRaw ||
4394 n == m->memory_at(Compile::AliasIdxRaw)) {
4395 expected_wide_mem = true;
4396 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
4397 // memory can "leak through" calls on channels that
4398 // are write-once. Allow this also.
4399 expected_wide_mem = true;
4400 }
4401 assert(expected_wide_mem, "expected narrow slice replacement");
4402 }
4403 }
4404 #else // !ASSERT
4405 #define verify_memory_slice(m,i,n) (void)(0) // PRODUCT version is no-op
4406 #endif
4409 //-----------------------------memory_at---------------------------------------
4410 Node* MergeMemNode::memory_at(uint alias_idx) const {
4411 assert(alias_idx >= Compile::AliasIdxRaw ||
4412 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0,
4413 "must avoid base_memory and AliasIdxTop");
4415 // Otherwise, it is a narrow slice.
4416 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
4417 Compile *C = Compile::current();
4418 if (is_empty_memory(n)) {
4419 // the array is sparse; empty slots are the "top" node
4420 n = base_memory();
4421 assert(Node::in_dump()
4422 || n == NULL || n->bottom_type() == Type::TOP
4423 || n->adr_type() == NULL // address is TOP
4424 || n->adr_type() == TypePtr::BOTTOM
4425 || n->adr_type() == TypeRawPtr::BOTTOM
4426 || Compile::current()->AliasLevel() == 0,
4427 "must be a wide memory");
4428 // AliasLevel == 0 if we are organizing the memory states manually.
4429 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
4430 } else {
4431 // make sure the stored slice is sane
4432 #ifdef ASSERT
4433 if (is_error_reported() || Node::in_dump()) {
4434 } else if (might_be_same(n, base_memory())) {
4435 // Give it a pass: It is a mostly harmless repetition of the base.
4436 // This can arise normally from node subsumption during optimization.
4437 } else {
4438 verify_memory_slice(this, alias_idx, n);
4439 }
4440 #endif
4441 }
4442 return n;
4443 }
4445 //---------------------------set_memory_at-------------------------------------
4446 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
4447 verify_memory_slice(this, alias_idx, n);
4448 Node* empty_mem = empty_memory();
4449 if (n == base_memory()) n = empty_mem; // collapse default
4450 uint need_req = alias_idx+1;
4451 if (req() < need_req) {
4452 if (n == empty_mem) return; // already the default, so do not grow me
4453 // grow the sparse array
4454 do {
4455 add_req(empty_mem);
4456 } while (req() < need_req);
4457 }
4458 set_req( alias_idx, n );
4459 }
4463 //--------------------------iteration_setup------------------------------------
4464 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
4465 if (other != NULL) {
4466 grow_to_match(other);
4467 // invariant: the finite support of mm2 is within mm->req()
4468 #ifdef ASSERT
4469 for (uint i = req(); i < other->req(); i++) {
4470 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
4471 }
4472 #endif
4473 }
4474 // Replace spurious copies of base_memory by top.
4475 Node* base_mem = base_memory();
4476 if (base_mem != NULL && !base_mem->is_top()) {
4477 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
4478 if (in(i) == base_mem)
4479 set_req(i, empty_memory());
4480 }
4481 }
4482 }
4484 //---------------------------grow_to_match-------------------------------------
4485 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
4486 Node* empty_mem = empty_memory();
4487 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
4488 // look for the finite support of the other memory
4489 for (uint i = other->req(); --i >= req(); ) {
4490 if (other->in(i) != empty_mem) {
4491 uint new_len = i+1;
4492 while (req() < new_len) add_req(empty_mem);
4493 break;
4494 }
4495 }
4496 }
4498 //---------------------------verify_sparse-------------------------------------
4499 #ifndef PRODUCT
4500 bool MergeMemNode::verify_sparse() const {
4501 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
4502 Node* base_mem = base_memory();
4503 // The following can happen in degenerate cases, since empty==top.
4504 if (is_empty_memory(base_mem)) return true;
4505 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4506 assert(in(i) != NULL, "sane slice");
4507 if (in(i) == base_mem) return false; // should have been the sentinel value!
4508 }
4509 return true;
4510 }
4512 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
4513 Node* n;
4514 n = mm->in(idx);
4515 if (mem == n) return true; // might be empty_memory()
4516 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
4517 if (mem == n) return true;
4518 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) {
4519 if (mem == n) return true;
4520 if (n == NULL) break;
4521 }
4522 return false;
4523 }
4524 #endif // !PRODUCT