1 /* 2 * Copyright (c) 1997, 2015, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "classfile/systemDictionary.hpp" 27 #include "compiler/compileLog.hpp" 28 #include "memory/allocation.inline.hpp" 29 #include "oops/objArrayKlass.hpp" 30 #include "opto/addnode.hpp" 31 #include "opto/arraycopynode.hpp" 32 #include "opto/cfgnode.hpp" 33 #include "opto/compile.hpp" 34 #include "opto/connode.hpp" 35 #include "opto/convertnode.hpp" 36 #include "opto/loopnode.hpp" 37 #include "opto/machnode.hpp" 38 #include "opto/matcher.hpp" 39 #include "opto/memnode.hpp" 40 #include "opto/mulnode.hpp" 41 #include "opto/narrowptrnode.hpp" 42 #include "opto/phaseX.hpp" 43 #include "opto/regmask.hpp" 44 #include "utilities/copy.hpp" 45 46 // Portions of code courtesy of Clifford Click 47 48 // Optimization - Graph Style 49 50 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st); 51 52 //============================================================================= 53 uint MemNode::size_of() const { return sizeof(*this); } 54 55 const TypePtr *MemNode::adr_type() const { 56 Node* adr = in(Address); 57 if (adr == NULL) return NULL; // node is dead 58 const TypePtr* cross_check = NULL; 59 DEBUG_ONLY(cross_check = _adr_type); 60 return calculate_adr_type(adr->bottom_type(), cross_check); 61 } 62 63 #ifndef PRODUCT 64 void MemNode::dump_spec(outputStream *st) const { 65 if (in(Address) == NULL) return; // node is dead 66 #ifndef ASSERT 67 // fake the missing field 68 const TypePtr* _adr_type = NULL; 69 if (in(Address) != NULL) 70 _adr_type = in(Address)->bottom_type()->isa_ptr(); 71 #endif 72 dump_adr_type(this, _adr_type, st); 73 74 Compile* C = Compile::current(); 75 if( C->alias_type(_adr_type)->is_volatile() ) 76 st->print(" Volatile!"); 77 } 78 79 void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) { 80 st->print(" @"); 81 if (adr_type == NULL) { 82 st->print("NULL"); 83 } else { 84 adr_type->dump_on(st); 85 Compile* C = Compile::current(); 86 Compile::AliasType* atp = NULL; 87 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type); 88 if (atp == NULL) 89 st->print(", idx=?\?;"); 90 else if (atp->index() == Compile::AliasIdxBot) 91 st->print(", idx=Bot;"); 92 else if (atp->index() == Compile::AliasIdxTop) 93 st->print(", idx=Top;"); 94 else if (atp->index() == Compile::AliasIdxRaw) 95 st->print(", idx=Raw;"); 96 else { 97 ciField* field = atp->field(); 98 if (field) { 99 st->print(", name="); 100 field->print_name_on(st); 101 } 102 st->print(", idx=%d;", atp->index()); 103 } 104 } 105 } 106 107 extern void print_alias_types(); 108 109 #endif 110 111 static bool membar_for_arraycopy_helper(const TypeOopPtr *t_oop, Node* n, PhaseTransform *phase) { 112 if (n->is_Proj()) { 113 n = n->in(0); 114 if (n->is_Call() && n->as_Call()->may_modify(t_oop, phase)) { 115 return true; 116 } 117 } 118 return false; 119 } 120 121 static bool membar_for_arraycopy(const TypeOopPtr *t_oop, MemBarNode* mb, PhaseTransform *phase) { 122 Node* mem = mb->in(TypeFunc::Memory); 123 124 if (mem->is_MergeMem()) { 125 Node* n = mem->as_MergeMem()->memory_at(Compile::AliasIdxRaw); 126 if (membar_for_arraycopy_helper(t_oop, n, phase)) { 127 return true; 128 } else if (n->is_Phi()) { 129 for (uint i = 1; i < n->req(); i++) { 130 if (n->in(i) != NULL) { 131 if (membar_for_arraycopy_helper(t_oop, n->in(i), phase)) { 132 return true; 133 } 134 } 135 } 136 } 137 } 138 139 return false; 140 } 141 142 Node *MemNode::optimize_simple_memory_chain(Node *mchain, const TypeOopPtr *t_oop, Node *load, PhaseGVN *phase) { 143 assert((t_oop != NULL), "sanity"); 144 bool is_instance = t_oop->is_known_instance_field(); 145 bool is_boxed_value_load = t_oop->is_ptr_to_boxed_value() && 146 (load != NULL) && load->is_Load() && 147 (phase->is_IterGVN() != NULL); 148 if (!(is_instance || is_boxed_value_load)) 149 return mchain; // don't try to optimize non-instance types 150 uint instance_id = t_oop->instance_id(); 151 Node *start_mem = phase->C->start()->proj_out(TypeFunc::Memory); 152 Node *prev = NULL; 153 Node *result = mchain; 154 while (prev != result) { 155 prev = result; 156 if (result == start_mem) 157 break; // hit one of our sentinels 158 // skip over a call which does not affect this memory slice 159 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) { 160 Node *proj_in = result->in(0); 161 if (proj_in->is_Allocate() && proj_in->_idx == instance_id) { 162 break; // hit one of our sentinels 163 } else if (proj_in->is_Call()) { 164 // ArrayCopyNodes processed here as well 165 CallNode *call = proj_in->as_Call(); 166 if (!call->may_modify(t_oop, phase)) { // returns false for instances 167 result = call->in(TypeFunc::Memory); 168 } 169 } else if (proj_in->is_Initialize()) { 170 AllocateNode* alloc = proj_in->as_Initialize()->allocation(); 171 // Stop if this is the initialization for the object instance which 172 // contains this memory slice, otherwise skip over it. 173 if ((alloc == NULL) || (alloc->_idx == instance_id)) { 174 break; 175 } 176 if (is_instance) { 177 result = proj_in->in(TypeFunc::Memory); 178 } else if (is_boxed_value_load) { 179 Node* klass = alloc->in(AllocateNode::KlassNode); 180 const TypeKlassPtr* tklass = phase->type(klass)->is_klassptr(); 181 if (tklass->klass_is_exact() && !tklass->klass()->equals(t_oop->klass())) { 182 result = proj_in->in(TypeFunc::Memory); // not related allocation 183 } 184 } 185 } else if (proj_in->is_MemBar()) { 186 if (membar_for_arraycopy(t_oop, proj_in->as_MemBar(), phase)) { 187 break; 188 } 189 result = proj_in->in(TypeFunc::Memory); 190 } else { 191 assert(false, "unexpected projection"); 192 } 193 } else if (result->is_ClearArray()) { 194 if (!is_instance || !ClearArrayNode::step_through(&result, instance_id, phase)) { 195 // Can not bypass initialization of the instance 196 // we are looking for. 197 break; 198 } 199 // Otherwise skip it (the call updated 'result' value). 200 } else if (result->is_MergeMem()) { 201 result = step_through_mergemem(phase, result->as_MergeMem(), t_oop, NULL, tty); 202 } 203 } 204 return result; 205 } 206 207 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, Node *load, PhaseGVN *phase) { 208 const TypeOopPtr* t_oop = t_adr->isa_oopptr(); 209 if (t_oop == NULL) 210 return mchain; // don't try to optimize non-oop types 211 Node* result = optimize_simple_memory_chain(mchain, t_oop, load, phase); 212 bool is_instance = t_oop->is_known_instance_field(); 213 PhaseIterGVN *igvn = phase->is_IterGVN(); 214 if (is_instance && igvn != NULL && result->is_Phi()) { 215 PhiNode *mphi = result->as_Phi(); 216 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required"); 217 const TypePtr *t = mphi->adr_type(); 218 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM || 219 t->isa_oopptr() && !t->is_oopptr()->is_known_instance() && 220 t->is_oopptr()->cast_to_exactness(true) 221 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr()) 222 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop) { 223 // clone the Phi with our address type 224 result = mphi->split_out_instance(t_adr, igvn); 225 } else { 226 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain"); 227 } 228 } 229 return result; 230 } 231 232 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) { 233 uint alias_idx = phase->C->get_alias_index(tp); 234 Node *mem = mmem; 235 #ifdef ASSERT 236 { 237 // Check that current type is consistent with the alias index used during graph construction 238 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx"); 239 bool consistent = adr_check == NULL || adr_check->empty() || 240 phase->C->must_alias(adr_check, alias_idx ); 241 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3] 242 if( !consistent && adr_check != NULL && !adr_check->empty() && 243 tp->isa_aryptr() && tp->offset() == Type::OffsetBot && 244 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot && 245 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() || 246 adr_check->offset() == oopDesc::klass_offset_in_bytes() || 247 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) { 248 // don't assert if it is dead code. 249 consistent = true; 250 } 251 if( !consistent ) { 252 st->print("alias_idx==%d, adr_check==", alias_idx); 253 if( adr_check == NULL ) { 254 st->print("NULL"); 255 } else { 256 adr_check->dump(); 257 } 258 st->cr(); 259 print_alias_types(); 260 assert(consistent, "adr_check must match alias idx"); 261 } 262 } 263 #endif 264 // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally 265 // means an array I have not precisely typed yet. Do not do any 266 // alias stuff with it any time soon. 267 const TypeOopPtr *toop = tp->isa_oopptr(); 268 if( tp->base() != Type::AnyPtr && 269 !(toop && 270 toop->klass() != NULL && 271 toop->klass()->is_java_lang_Object() && 272 toop->offset() == Type::OffsetBot) ) { 273 // compress paths and change unreachable cycles to TOP 274 // If not, we can update the input infinitely along a MergeMem cycle 275 // Equivalent code in PhiNode::Ideal 276 Node* m = phase->transform(mmem); 277 // If transformed to a MergeMem, get the desired slice 278 // Otherwise the returned node represents memory for every slice 279 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m; 280 // Update input if it is progress over what we have now 281 } 282 return mem; 283 } 284 285 //--------------------------Ideal_common--------------------------------------- 286 // Look for degenerate control and memory inputs. Bypass MergeMem inputs. 287 // Unhook non-raw memories from complete (macro-expanded) initializations. 288 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) { 289 // If our control input is a dead region, kill all below the region 290 Node *ctl = in(MemNode::Control); 291 if (ctl && remove_dead_region(phase, can_reshape)) 292 return this; 293 ctl = in(MemNode::Control); 294 // Don't bother trying to transform a dead node 295 if (ctl && ctl->is_top()) return NodeSentinel; 296 297 PhaseIterGVN *igvn = phase->is_IterGVN(); 298 // Wait if control on the worklist. 299 if (ctl && can_reshape && igvn != NULL) { 300 Node* bol = NULL; 301 Node* cmp = NULL; 302 if (ctl->in(0)->is_If()) { 303 assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity"); 304 bol = ctl->in(0)->in(1); 305 if (bol->is_Bool()) 306 cmp = ctl->in(0)->in(1)->in(1); 307 } 308 if (igvn->_worklist.member(ctl) || 309 (bol != NULL && igvn->_worklist.member(bol)) || 310 (cmp != NULL && igvn->_worklist.member(cmp)) ) { 311 // This control path may be dead. 312 // Delay this memory node transformation until the control is processed. 313 phase->is_IterGVN()->_worklist.push(this); 314 return NodeSentinel; // caller will return NULL 315 } 316 } 317 // Ignore if memory is dead, or self-loop 318 Node *mem = in(MemNode::Memory); 319 if (phase->type( mem ) == Type::TOP) return NodeSentinel; // caller will return NULL 320 assert(mem != this, "dead loop in MemNode::Ideal"); 321 322 if (can_reshape && igvn != NULL && igvn->_worklist.member(mem)) { 323 // This memory slice may be dead. 324 // Delay this mem node transformation until the memory is processed. 325 phase->is_IterGVN()->_worklist.push(this); 326 return NodeSentinel; // caller will return NULL 327 } 328 329 Node *address = in(MemNode::Address); 330 const Type *t_adr = phase->type(address); 331 if (t_adr == Type::TOP) return NodeSentinel; // caller will return NULL 332 333 if (can_reshape && igvn != NULL && 334 (igvn->_worklist.member(address) || 335 igvn->_worklist.size() > 0 && (t_adr != adr_type())) ) { 336 // The address's base and type may change when the address is processed. 337 // Delay this mem node transformation until the address is processed. 338 phase->is_IterGVN()->_worklist.push(this); 339 return NodeSentinel; // caller will return NULL 340 } 341 342 // Do NOT remove or optimize the next lines: ensure a new alias index 343 // is allocated for an oop pointer type before Escape Analysis. 344 // Note: C++ will not remove it since the call has side effect. 345 if (t_adr->isa_oopptr()) { 346 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr()); 347 } 348 349 Node* base = NULL; 350 if (address->is_AddP()) { 351 base = address->in(AddPNode::Base); 352 } 353 if (base != NULL && phase->type(base)->higher_equal(TypePtr::NULL_PTR) && 354 !t_adr->isa_rawptr()) { 355 // Note: raw address has TOP base and top->higher_equal(TypePtr::NULL_PTR) is true. 356 // Skip this node optimization if its address has TOP base. 357 return NodeSentinel; // caller will return NULL 358 } 359 360 // Avoid independent memory operations 361 Node* old_mem = mem; 362 363 // The code which unhooks non-raw memories from complete (macro-expanded) 364 // initializations was removed. After macro-expansion all stores catched 365 // by Initialize node became raw stores and there is no information 366 // which memory slices they modify. So it is unsafe to move any memory 367 // operation above these stores. Also in most cases hooked non-raw memories 368 // were already unhooked by using information from detect_ptr_independence() 369 // and find_previous_store(). 370 371 if (mem->is_MergeMem()) { 372 MergeMemNode* mmem = mem->as_MergeMem(); 373 const TypePtr *tp = t_adr->is_ptr(); 374 375 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty); 376 } 377 378 if (mem != old_mem) { 379 set_req(MemNode::Memory, mem); 380 if (can_reshape && old_mem->outcnt() == 0) { 381 igvn->_worklist.push(old_mem); 382 } 383 if (phase->type( mem ) == Type::TOP) return NodeSentinel; 384 return this; 385 } 386 387 // let the subclass continue analyzing... 388 return NULL; 389 } 390 391 // Helper function for proving some simple control dominations. 392 // Attempt to prove that all control inputs of 'dom' dominate 'sub'. 393 // Already assumes that 'dom' is available at 'sub', and that 'sub' 394 // is not a constant (dominated by the method's StartNode). 395 // Used by MemNode::find_previous_store to prove that the 396 // control input of a memory operation predates (dominates) 397 // an allocation it wants to look past. 398 bool MemNode::all_controls_dominate(Node* dom, Node* sub) { 399 if (dom == NULL || dom->is_top() || sub == NULL || sub->is_top()) 400 return false; // Conservative answer for dead code 401 402 // Check 'dom'. Skip Proj and CatchProj nodes. 403 dom = dom->find_exact_control(dom); 404 if (dom == NULL || dom->is_top()) 405 return false; // Conservative answer for dead code 406 407 if (dom == sub) { 408 // For the case when, for example, 'sub' is Initialize and the original 409 // 'dom' is Proj node of the 'sub'. 410 return false; 411 } 412 413 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub) 414 return true; 415 416 // 'dom' dominates 'sub' if its control edge and control edges 417 // of all its inputs dominate or equal to sub's control edge. 418 419 // Currently 'sub' is either Allocate, Initialize or Start nodes. 420 // Or Region for the check in LoadNode::Ideal(); 421 // 'sub' should have sub->in(0) != NULL. 422 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() || 423 sub->is_Region() || sub->is_Call(), "expecting only these nodes"); 424 425 // Get control edge of 'sub'. 426 Node* orig_sub = sub; 427 sub = sub->find_exact_control(sub->in(0)); 428 if (sub == NULL || sub->is_top()) 429 return false; // Conservative answer for dead code 430 431 assert(sub->is_CFG(), "expecting control"); 432 433 if (sub == dom) 434 return true; 435 436 if (sub->is_Start() || sub->is_Root()) 437 return false; 438 439 { 440 // Check all control edges of 'dom'. 441 442 ResourceMark rm; 443 Arena* arena = Thread::current()->resource_area(); 444 Node_List nlist(arena); 445 Unique_Node_List dom_list(arena); 446 447 dom_list.push(dom); 448 bool only_dominating_controls = false; 449 450 for (uint next = 0; next < dom_list.size(); next++) { 451 Node* n = dom_list.at(next); 452 if (n == orig_sub) 453 return false; // One of dom's inputs dominated by sub. 454 if (!n->is_CFG() && n->pinned()) { 455 // Check only own control edge for pinned non-control nodes. 456 n = n->find_exact_control(n->in(0)); 457 if (n == NULL || n->is_top()) 458 return false; // Conservative answer for dead code 459 assert(n->is_CFG(), "expecting control"); 460 dom_list.push(n); 461 } else if (n->is_Con() || n->is_Start() || n->is_Root()) { 462 only_dominating_controls = true; 463 } else if (n->is_CFG()) { 464 if (n->dominates(sub, nlist)) 465 only_dominating_controls = true; 466 else 467 return false; 468 } else { 469 // First, own control edge. 470 Node* m = n->find_exact_control(n->in(0)); 471 if (m != NULL) { 472 if (m->is_top()) 473 return false; // Conservative answer for dead code 474 dom_list.push(m); 475 } 476 // Now, the rest of edges. 477 uint cnt = n->req(); 478 for (uint i = 1; i < cnt; i++) { 479 m = n->find_exact_control(n->in(i)); 480 if (m == NULL || m->is_top()) 481 continue; 482 dom_list.push(m); 483 } 484 } 485 } 486 return only_dominating_controls; 487 } 488 } 489 490 //---------------------detect_ptr_independence--------------------------------- 491 // Used by MemNode::find_previous_store to prove that two base 492 // pointers are never equal. 493 // The pointers are accompanied by their associated allocations, 494 // if any, which have been previously discovered by the caller. 495 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1, 496 Node* p2, AllocateNode* a2, 497 PhaseTransform* phase) { 498 // Attempt to prove that these two pointers cannot be aliased. 499 // They may both manifestly be allocations, and they should differ. 500 // Or, if they are not both allocations, they can be distinct constants. 501 // Otherwise, one is an allocation and the other a pre-existing value. 502 if (a1 == NULL && a2 == NULL) { // neither an allocation 503 return (p1 != p2) && p1->is_Con() && p2->is_Con(); 504 } else if (a1 != NULL && a2 != NULL) { // both allocations 505 return (a1 != a2); 506 } else if (a1 != NULL) { // one allocation a1 507 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.) 508 return all_controls_dominate(p2, a1); 509 } else { //(a2 != NULL) // one allocation a2 510 return all_controls_dominate(p1, a2); 511 } 512 return false; 513 } 514 515 516 // Find an arraycopy that must have set (can_see_stored_value=true) or 517 // could have set (can_see_stored_value=false) the value for this load 518 Node* LoadNode::find_previous_arraycopy(PhaseTransform* phase, Node* ld_alloc, Node*& mem, bool can_see_stored_value) const { 519 if (mem->is_Proj() && mem->in(0) != NULL && (mem->in(0)->Opcode() == Op_MemBarStoreStore || 520 mem->in(0)->Opcode() == Op_MemBarCPUOrder)) { 521 Node* mb = mem->in(0); 522 if (mb->in(0) != NULL && mb->in(0)->is_Proj() && 523 mb->in(0)->in(0) != NULL && mb->in(0)->in(0)->is_ArrayCopy()) { 524 ArrayCopyNode* ac = mb->in(0)->in(0)->as_ArrayCopy(); 525 if (ac->is_clonebasic()) { 526 intptr_t offset; 527 AllocateNode* alloc = AllocateNode::Ideal_allocation(ac->in(ArrayCopyNode::Dest), phase, offset); 528 assert(alloc != NULL && alloc->initialization()->is_complete_with_arraycopy(), "broken allocation"); 529 if (alloc == ld_alloc) { 530 return ac; 531 } 532 } 533 } 534 } else if (mem->is_Proj() && mem->in(0) != NULL && mem->in(0)->is_ArrayCopy()) { 535 ArrayCopyNode* ac = mem->in(0)->as_ArrayCopy(); 536 537 if (ac->is_arraycopy_validated() || 538 ac->is_copyof_validated() || 539 ac->is_copyofrange_validated()) { 540 Node* ld_addp = in(MemNode::Address); 541 if (ld_addp->is_AddP()) { 542 Node* ld_base = ld_addp->in(AddPNode::Address); 543 Node* ld_offs = ld_addp->in(AddPNode::Offset); 544 545 Node* dest = ac->in(ArrayCopyNode::Dest); 546 547 if (dest == ld_base) { 548 Node* src_pos = ac->in(ArrayCopyNode::SrcPos); 549 Node* dest_pos = ac->in(ArrayCopyNode::DestPos); 550 Node* len = ac->in(ArrayCopyNode::Length); 551 552 const TypeInt *dest_pos_t = phase->type(dest_pos)->isa_int(); 553 const TypeX *ld_offs_t = phase->type(ld_offs)->isa_intptr_t(); 554 const TypeInt *len_t = phase->type(len)->isa_int(); 555 const TypeAryPtr* ary_t = phase->type(dest)->isa_aryptr(); 556 557 if (dest_pos_t != NULL && ld_offs_t != NULL && len_t != NULL && ary_t != NULL) { 558 BasicType ary_elem = ary_t->klass()->as_array_klass()->element_type()->basic_type(); 559 uint header = arrayOopDesc::base_offset_in_bytes(ary_elem); 560 uint elemsize = type2aelembytes(ary_elem); 561 562 intptr_t dest_pos_plus_len_lo = (((intptr_t)dest_pos_t->_lo) + len_t->_lo) * elemsize + header; 563 intptr_t dest_pos_plus_len_hi = (((intptr_t)dest_pos_t->_hi) + len_t->_hi) * elemsize + header; 564 intptr_t dest_pos_lo = ((intptr_t)dest_pos_t->_lo) * elemsize + header; 565 intptr_t dest_pos_hi = ((intptr_t)dest_pos_t->_hi) * elemsize + header; 566 567 if (can_see_stored_value) { 568 if (ld_offs_t->_lo >= dest_pos_hi && ld_offs_t->_hi < dest_pos_plus_len_lo) { 569 return ac; 570 } 571 } else { 572 if (ld_offs_t->_hi < dest_pos_lo || ld_offs_t->_lo >= dest_pos_plus_len_hi) { 573 mem = ac->in(TypeFunc::Memory); 574 } 575 return ac; 576 } 577 } 578 } 579 } 580 } 581 } 582 return NULL; 583 } 584 585 // The logic for reordering loads and stores uses four steps: 586 // (a) Walk carefully past stores and initializations which we 587 // can prove are independent of this load. 588 // (b) Observe that the next memory state makes an exact match 589 // with self (load or store), and locate the relevant store. 590 // (c) Ensure that, if we were to wire self directly to the store, 591 // the optimizer would fold it up somehow. 592 // (d) Do the rewiring, and return, depending on some other part of 593 // the optimizer to fold up the load. 594 // This routine handles steps (a) and (b). Steps (c) and (d) are 595 // specific to loads and stores, so they are handled by the callers. 596 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.) 597 // 598 Node* MemNode::find_previous_store(PhaseTransform* phase) { 599 Node* ctrl = in(MemNode::Control); 600 Node* adr = in(MemNode::Address); 601 intptr_t offset = 0; 602 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 603 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase); 604 605 if (offset == Type::OffsetBot) 606 return NULL; // cannot unalias unless there are precise offsets 607 608 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr(); 609 610 intptr_t size_in_bytes = memory_size(); 611 612 Node* mem = in(MemNode::Memory); // start searching here... 613 614 int cnt = 50; // Cycle limiter 615 for (;;) { // While we can dance past unrelated stores... 616 if (--cnt < 0) break; // Caught in cycle or a complicated dance? 617 618 Node* prev = mem; 619 if (mem->is_Store()) { 620 Node* st_adr = mem->in(MemNode::Address); 621 intptr_t st_offset = 0; 622 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset); 623 if (st_base == NULL) 624 break; // inscrutable pointer 625 if (st_offset != offset && st_offset != Type::OffsetBot) { 626 const int MAX_STORE = BytesPerLong; 627 if (st_offset >= offset + size_in_bytes || 628 st_offset <= offset - MAX_STORE || 629 st_offset <= offset - mem->as_Store()->memory_size()) { 630 // Success: The offsets are provably independent. 631 // (You may ask, why not just test st_offset != offset and be done? 632 // The answer is that stores of different sizes can co-exist 633 // in the same sequence of RawMem effects. We sometimes initialize 634 // a whole 'tile' of array elements with a single jint or jlong.) 635 mem = mem->in(MemNode::Memory); 636 continue; // (a) advance through independent store memory 637 } 638 } 639 if (st_base != base && 640 detect_ptr_independence(base, alloc, 641 st_base, 642 AllocateNode::Ideal_allocation(st_base, phase), 643 phase)) { 644 // Success: The bases are provably independent. 645 mem = mem->in(MemNode::Memory); 646 continue; // (a) advance through independent store memory 647 } 648 649 // (b) At this point, if the bases or offsets do not agree, we lose, 650 // since we have not managed to prove 'this' and 'mem' independent. 651 if (st_base == base && st_offset == offset) { 652 return mem; // let caller handle steps (c), (d) 653 } 654 655 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) { 656 InitializeNode* st_init = mem->in(0)->as_Initialize(); 657 AllocateNode* st_alloc = st_init->allocation(); 658 if (st_alloc == NULL) 659 break; // something degenerated 660 bool known_identical = false; 661 bool known_independent = false; 662 if (alloc == st_alloc) 663 known_identical = true; 664 else if (alloc != NULL) 665 known_independent = true; 666 else if (all_controls_dominate(this, st_alloc)) 667 known_independent = true; 668 669 if (known_independent) { 670 // The bases are provably independent: Either they are 671 // manifestly distinct allocations, or else the control 672 // of this load dominates the store's allocation. 673 int alias_idx = phase->C->get_alias_index(adr_type()); 674 if (alias_idx == Compile::AliasIdxRaw) { 675 mem = st_alloc->in(TypeFunc::Memory); 676 } else { 677 mem = st_init->memory(alias_idx); 678 } 679 continue; // (a) advance through independent store memory 680 } 681 682 // (b) at this point, if we are not looking at a store initializing 683 // the same allocation we are loading from, we lose. 684 if (known_identical) { 685 // From caller, can_see_stored_value will consult find_captured_store. 686 return mem; // let caller handle steps (c), (d) 687 } 688 689 } else if (find_previous_arraycopy(phase, alloc, mem, false) != NULL) { 690 if (prev != mem) { 691 // Found an arraycopy but it doesn't affect that load 692 continue; 693 } 694 // Found an arraycopy that may affect that load 695 return mem; 696 } else if (addr_t != NULL && addr_t->is_known_instance_field()) { 697 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN. 698 if (mem->is_Proj() && mem->in(0)->is_Call()) { 699 // ArrayCopyNodes processed here as well. 700 CallNode *call = mem->in(0)->as_Call(); 701 if (!call->may_modify(addr_t, phase)) { 702 mem = call->in(TypeFunc::Memory); 703 continue; // (a) advance through independent call memory 704 } 705 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) { 706 if (membar_for_arraycopy(addr_t, mem->in(0)->as_MemBar(), phase)) { 707 break; 708 } 709 mem = mem->in(0)->in(TypeFunc::Memory); 710 continue; // (a) advance through independent MemBar memory 711 } else if (mem->is_ClearArray()) { 712 if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) { 713 // (the call updated 'mem' value) 714 continue; // (a) advance through independent allocation memory 715 } else { 716 // Can not bypass initialization of the instance 717 // we are looking for. 718 return mem; 719 } 720 } else if (mem->is_MergeMem()) { 721 int alias_idx = phase->C->get_alias_index(adr_type()); 722 mem = mem->as_MergeMem()->memory_at(alias_idx); 723 continue; // (a) advance through independent MergeMem memory 724 } 725 } 726 727 // Unless there is an explicit 'continue', we must bail out here, 728 // because 'mem' is an inscrutable memory state (e.g., a call). 729 break; 730 } 731 732 return NULL; // bail out 733 } 734 735 //----------------------calculate_adr_type------------------------------------- 736 // Helper function. Notices when the given type of address hits top or bottom. 737 // Also, asserts a cross-check of the type against the expected address type. 738 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) { 739 if (t == Type::TOP) return NULL; // does not touch memory any more? 740 #ifdef PRODUCT 741 cross_check = NULL; 742 #else 743 if (!VerifyAliases || is_error_reported() || Node::in_dump()) cross_check = NULL; 744 #endif 745 const TypePtr* tp = t->isa_ptr(); 746 if (tp == NULL) { 747 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide"); 748 return TypePtr::BOTTOM; // touches lots of memory 749 } else { 750 #ifdef ASSERT 751 // %%%% [phh] We don't check the alias index if cross_check is 752 // TypeRawPtr::BOTTOM. Needs to be investigated. 753 if (cross_check != NULL && 754 cross_check != TypePtr::BOTTOM && 755 cross_check != TypeRawPtr::BOTTOM) { 756 // Recheck the alias index, to see if it has changed (due to a bug). 757 Compile* C = Compile::current(); 758 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp), 759 "must stay in the original alias category"); 760 // The type of the address must be contained in the adr_type, 761 // disregarding "null"-ness. 762 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.) 763 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr(); 764 assert(cross_check->meet(tp_notnull) == cross_check->remove_speculative(), 765 "real address must not escape from expected memory type"); 766 } 767 #endif 768 return tp; 769 } 770 } 771 772 //============================================================================= 773 // Should LoadNode::Ideal() attempt to remove control edges? 774 bool LoadNode::can_remove_control() const { 775 return true; 776 } 777 uint LoadNode::size_of() const { return sizeof(*this); } 778 uint LoadNode::cmp( const Node &n ) const 779 { return !Type::cmp( _type, ((LoadNode&)n)._type ); } 780 const Type *LoadNode::bottom_type() const { return _type; } 781 uint LoadNode::ideal_reg() const { 782 return _type->ideal_reg(); 783 } 784 785 #ifndef PRODUCT 786 void LoadNode::dump_spec(outputStream *st) const { 787 MemNode::dump_spec(st); 788 if( !Verbose && !WizardMode ) { 789 // standard dump does this in Verbose and WizardMode 790 st->print(" #"); _type->dump_on(st); 791 } 792 if (!_depends_only_on_test) { 793 st->print(" (does not depend only on test)"); 794 } 795 } 796 #endif 797 798 #ifdef ASSERT 799 //----------------------------is_immutable_value------------------------------- 800 // Helper function to allow a raw load without control edge for some cases 801 bool LoadNode::is_immutable_value(Node* adr) { 802 return (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() && 803 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal && 804 (adr->in(AddPNode::Offset)->find_intptr_t_con(-1) == 805 in_bytes(JavaThread::osthread_offset()))); 806 } 807 #endif 808 809 //----------------------------LoadNode::make----------------------------------- 810 // Polymorphic factory method: 811 Node *LoadNode::make(PhaseGVN& gvn, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt, MemOrd mo, ControlDependency control_dependency) { 812 Compile* C = gvn.C; 813 814 // sanity check the alias category against the created node type 815 assert(!(adr_type->isa_oopptr() && 816 adr_type->offset() == oopDesc::klass_offset_in_bytes()), 817 "use LoadKlassNode instead"); 818 assert(!(adr_type->isa_aryptr() && 819 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()), 820 "use LoadRangeNode instead"); 821 // Check control edge of raw loads 822 assert( ctl != NULL || C->get_alias_index(adr_type) != Compile::AliasIdxRaw || 823 // oop will be recorded in oop map if load crosses safepoint 824 rt->isa_oopptr() || is_immutable_value(adr), 825 "raw memory operations should have control edge"); 826 switch (bt) { 827 case T_BOOLEAN: return new LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); 828 case T_BYTE: return new LoadBNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); 829 case T_INT: return new LoadINode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); 830 case T_CHAR: return new LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); 831 case T_SHORT: return new LoadSNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); 832 case T_LONG: return new LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency); 833 case T_FLOAT: return new LoadFNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); 834 case T_DOUBLE: return new LoadDNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); 835 case T_ADDRESS: return new LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency); 836 case T_OBJECT: 837 #ifdef _LP64 838 if (adr->bottom_type()->is_ptr_to_narrowoop()) { 839 Node* load = gvn.transform(new LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo, control_dependency)); 840 return new DecodeNNode(load, load->bottom_type()->make_ptr()); 841 } else 842 #endif 843 { 844 assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop"); 845 return new LoadPNode(ctl, mem, adr, adr_type, rt->is_oopptr(), mo, control_dependency); 846 } 847 } 848 ShouldNotReachHere(); 849 return (LoadNode*)NULL; 850 } 851 852 LoadLNode* LoadLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo, ControlDependency control_dependency) { 853 bool require_atomic = true; 854 return new LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency, require_atomic); 855 } 856 857 LoadDNode* LoadDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo, ControlDependency control_dependency) { 858 bool require_atomic = true; 859 return new LoadDNode(ctl, mem, adr, adr_type, rt, mo, control_dependency, require_atomic); 860 } 861 862 863 864 //------------------------------hash------------------------------------------- 865 uint LoadNode::hash() const { 866 // unroll addition of interesting fields 867 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address); 868 } 869 870 static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) { 871 if ((atp != NULL) && (atp->index() >= Compile::AliasIdxRaw)) { 872 bool non_volatile = (atp->field() != NULL) && !atp->field()->is_volatile(); 873 bool is_stable_ary = FoldStableValues && 874 (tp != NULL) && (tp->isa_aryptr() != NULL) && 875 tp->isa_aryptr()->is_stable(); 876 877 return (eliminate_boxing && non_volatile) || is_stable_ary; 878 } 879 880 return false; 881 } 882 883 // Is the value loaded previously stored by an arraycopy? If so return 884 // a load node that reads from the source array so we may be able to 885 // optimize out the ArrayCopy node later. 886 Node* MemNode::can_see_arraycopy_value(Node* st, PhaseTransform* phase) const { 887 Node* ld_adr = in(MemNode::Address); 888 intptr_t ld_off = 0; 889 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off); 890 Node* ac = find_previous_arraycopy(phase, ld_alloc, st, true); 891 if (ac != NULL) { 892 assert(ac->is_ArrayCopy(), "what kind of node can this be?"); 893 assert(is_Load(), "only for loads"); 894 895 if (ac->as_ArrayCopy()->is_clonebasic()) { 896 assert(ld_alloc != NULL, "need an alloc"); 897 Node* ld = clone(); 898 Node* addp = in(MemNode::Address)->clone(); 899 assert(addp->is_AddP(), "address must be addp"); 900 assert(addp->in(AddPNode::Base) == ac->in(ArrayCopyNode::Dest)->in(AddPNode::Base), "strange pattern"); 901 assert(addp->in(AddPNode::Address) == ac->in(ArrayCopyNode::Dest)->in(AddPNode::Address), "strange pattern"); 902 addp->set_req(AddPNode::Base, ac->in(ArrayCopyNode::Src)->in(AddPNode::Base)); 903 addp->set_req(AddPNode::Address, ac->in(ArrayCopyNode::Src)->in(AddPNode::Address)); 904 ld->set_req(MemNode::Address, phase->transform(addp)); 905 if (in(0) != NULL) { 906 assert(ld_alloc->in(0) != NULL, "alloc must have control"); 907 ld->set_req(0, ld_alloc->in(0)); 908 } 909 return ld; 910 } else { 911 Node* ld = clone(); 912 Node* addp = in(MemNode::Address)->clone(); 913 assert(addp->in(AddPNode::Base) == addp->in(AddPNode::Address), "should be"); 914 addp->set_req(AddPNode::Base, ac->in(ArrayCopyNode::Src)); 915 addp->set_req(AddPNode::Address, ac->in(ArrayCopyNode::Src)); 916 917 const TypeAryPtr* ary_t = phase->type(in(MemNode::Address))->isa_aryptr(); 918 BasicType ary_elem = ary_t->klass()->as_array_klass()->element_type()->basic_type(); 919 uint header = arrayOopDesc::base_offset_in_bytes(ary_elem); 920 uint shift = exact_log2(type2aelembytes(ary_elem)); 921 922 Node* diff = phase->transform(new SubINode(ac->in(ArrayCopyNode::SrcPos), ac->in(ArrayCopyNode::DestPos))); 923 #ifdef _LP64 924 diff = phase->transform(new ConvI2LNode(diff)); 925 #endif 926 diff = phase->transform(new LShiftXNode(diff, phase->intcon(shift))); 927 928 Node* offset = phase->transform(new AddXNode(addp->in(AddPNode::Offset), diff)); 929 addp->set_req(AddPNode::Offset, offset); 930 ld->set_req(MemNode::Address, phase->transform(addp)); 931 932 if (in(0) != NULL) { 933 assert(ac->in(0) != NULL, "alloc must have control"); 934 ld->set_req(0, ac->in(0)); 935 } 936 return ld; 937 } 938 } 939 return NULL; 940 } 941 942 943 //---------------------------can_see_stored_value------------------------------ 944 // This routine exists to make sure this set of tests is done the same 945 // everywhere. We need to make a coordinated change: first LoadNode::Ideal 946 // will change the graph shape in a way which makes memory alive twice at the 947 // same time (uses the Oracle model of aliasing), then some 948 // LoadXNode::Identity will fold things back to the equivalence-class model 949 // of aliasing. 950 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const { 951 Node* ld_adr = in(MemNode::Address); 952 intptr_t ld_off = 0; 953 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off); 954 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr(); 955 Compile::AliasType* atp = (tp != NULL) ? phase->C->alias_type(tp) : NULL; 956 // This is more general than load from boxing objects. 957 if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) { 958 uint alias_idx = atp->index(); 959 bool final = !atp->is_rewritable(); 960 Node* result = NULL; 961 Node* current = st; 962 // Skip through chains of MemBarNodes checking the MergeMems for 963 // new states for the slice of this load. Stop once any other 964 // kind of node is encountered. Loads from final memory can skip 965 // through any kind of MemBar but normal loads shouldn't skip 966 // through MemBarAcquire since the could allow them to move out of 967 // a synchronized region. 968 while (current->is_Proj()) { 969 int opc = current->in(0)->Opcode(); 970 if ((final && (opc == Op_MemBarAcquire || 971 opc == Op_MemBarAcquireLock || 972 opc == Op_LoadFence)) || 973 opc == Op_MemBarRelease || 974 opc == Op_StoreFence || 975 opc == Op_MemBarReleaseLock || 976 opc == Op_MemBarStoreStore || 977 opc == Op_MemBarCPUOrder) { 978 Node* mem = current->in(0)->in(TypeFunc::Memory); 979 if (mem->is_MergeMem()) { 980 MergeMemNode* merge = mem->as_MergeMem(); 981 Node* new_st = merge->memory_at(alias_idx); 982 if (new_st == merge->base_memory()) { 983 // Keep searching 984 current = new_st; 985 continue; 986 } 987 // Save the new memory state for the slice and fall through 988 // to exit. 989 result = new_st; 990 } 991 } 992 break; 993 } 994 if (result != NULL) { 995 st = result; 996 } 997 } 998 999 // Loop around twice in the case Load -> Initialize -> Store. 1000 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.) 1001 for (int trip = 0; trip <= 1; trip++) { 1002 1003 if (st->is_Store()) { 1004 Node* st_adr = st->in(MemNode::Address); 1005 if (!phase->eqv(st_adr, ld_adr)) { 1006 // Try harder before giving up... Match raw and non-raw pointers. 1007 intptr_t st_off = 0; 1008 AllocateNode* alloc = AllocateNode::Ideal_allocation(st_adr, phase, st_off); 1009 if (alloc == NULL) return NULL; 1010 if (alloc != ld_alloc) return NULL; 1011 if (ld_off != st_off) return NULL; 1012 // At this point we have proven something like this setup: 1013 // A = Allocate(...) 1014 // L = LoadQ(, AddP(CastPP(, A.Parm),, #Off)) 1015 // S = StoreQ(, AddP(, A.Parm , #Off), V) 1016 // (Actually, we haven't yet proven the Q's are the same.) 1017 // In other words, we are loading from a casted version of 1018 // the same pointer-and-offset that we stored to. 1019 // Thus, we are able to replace L by V. 1020 } 1021 // Now prove that we have a LoadQ matched to a StoreQ, for some Q. 1022 if (store_Opcode() != st->Opcode()) 1023 return NULL; 1024 return st->in(MemNode::ValueIn); 1025 } 1026 1027 // A load from a freshly-created object always returns zero. 1028 // (This can happen after LoadNode::Ideal resets the load's memory input 1029 // to find_captured_store, which returned InitializeNode::zero_memory.) 1030 if (st->is_Proj() && st->in(0)->is_Allocate() && 1031 (st->in(0) == ld_alloc) && 1032 (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) { 1033 // return a zero value for the load's basic type 1034 // (This is one of the few places where a generic PhaseTransform 1035 // can create new nodes. Think of it as lazily manifesting 1036 // virtually pre-existing constants.) 1037 return phase->zerocon(memory_type()); 1038 } 1039 1040 // A load from an initialization barrier can match a captured store. 1041 if (st->is_Proj() && st->in(0)->is_Initialize()) { 1042 InitializeNode* init = st->in(0)->as_Initialize(); 1043 AllocateNode* alloc = init->allocation(); 1044 if ((alloc != NULL) && (alloc == ld_alloc)) { 1045 // examine a captured store value 1046 st = init->find_captured_store(ld_off, memory_size(), phase); 1047 if (st != NULL) { 1048 continue; // take one more trip around 1049 } 1050 } 1051 } 1052 1053 // Load boxed value from result of valueOf() call is input parameter. 1054 if (this->is_Load() && ld_adr->is_AddP() && 1055 (tp != NULL) && tp->is_ptr_to_boxed_value()) { 1056 intptr_t ignore = 0; 1057 Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore); 1058 if (base != NULL && base->is_Proj() && 1059 base->as_Proj()->_con == TypeFunc::Parms && 1060 base->in(0)->is_CallStaticJava() && 1061 base->in(0)->as_CallStaticJava()->is_boxing_method()) { 1062 return base->in(0)->in(TypeFunc::Parms); 1063 } 1064 } 1065 1066 break; 1067 } 1068 1069 return NULL; 1070 } 1071 1072 //----------------------is_instance_field_load_with_local_phi------------------ 1073 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) { 1074 if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl && 1075 in(Address)->is_AddP() ) { 1076 const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr(); 1077 // Only instances and boxed values. 1078 if( t_oop != NULL && 1079 (t_oop->is_ptr_to_boxed_value() || 1080 t_oop->is_known_instance_field()) && 1081 t_oop->offset() != Type::OffsetBot && 1082 t_oop->offset() != Type::OffsetTop) { 1083 return true; 1084 } 1085 } 1086 return false; 1087 } 1088 1089 //------------------------------Identity--------------------------------------- 1090 // Loads are identity if previous store is to same address 1091 Node *LoadNode::Identity( PhaseTransform *phase ) { 1092 // If the previous store-maker is the right kind of Store, and the store is 1093 // to the same address, then we are equal to the value stored. 1094 Node* mem = in(Memory); 1095 Node* value = can_see_stored_value(mem, phase); 1096 if( value ) { 1097 // byte, short & char stores truncate naturally. 1098 // A load has to load the truncated value which requires 1099 // some sort of masking operation and that requires an 1100 // Ideal call instead of an Identity call. 1101 if (memory_size() < BytesPerInt) { 1102 // If the input to the store does not fit with the load's result type, 1103 // it must be truncated via an Ideal call. 1104 if (!phase->type(value)->higher_equal(phase->type(this))) 1105 return this; 1106 } 1107 // (This works even when value is a Con, but LoadNode::Value 1108 // usually runs first, producing the singleton type of the Con.) 1109 return value; 1110 } 1111 1112 // Search for an existing data phi which was generated before for the same 1113 // instance's field to avoid infinite generation of phis in a loop. 1114 Node *region = mem->in(0); 1115 if (is_instance_field_load_with_local_phi(region)) { 1116 const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr(); 1117 int this_index = phase->C->get_alias_index(addr_t); 1118 int this_offset = addr_t->offset(); 1119 int this_iid = addr_t->instance_id(); 1120 if (!addr_t->is_known_instance() && 1121 addr_t->is_ptr_to_boxed_value()) { 1122 // Use _idx of address base (could be Phi node) for boxed values. 1123 intptr_t ignore = 0; 1124 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore); 1125 this_iid = base->_idx; 1126 } 1127 const Type* this_type = bottom_type(); 1128 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) { 1129 Node* phi = region->fast_out(i); 1130 if (phi->is_Phi() && phi != mem && 1131 phi->as_Phi()->is_same_inst_field(this_type, this_iid, this_index, this_offset)) { 1132 return phi; 1133 } 1134 } 1135 } 1136 1137 return this; 1138 } 1139 1140 // We're loading from an object which has autobox behaviour. 1141 // If this object is result of a valueOf call we'll have a phi 1142 // merging a newly allocated object and a load from the cache. 1143 // We want to replace this load with the original incoming 1144 // argument to the valueOf call. 1145 Node* LoadNode::eliminate_autobox(PhaseGVN* phase) { 1146 assert(phase->C->eliminate_boxing(), "sanity"); 1147 intptr_t ignore = 0; 1148 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore); 1149 if ((base == NULL) || base->is_Phi()) { 1150 // Push the loads from the phi that comes from valueOf up 1151 // through it to allow elimination of the loads and the recovery 1152 // of the original value. It is done in split_through_phi(). 1153 return NULL; 1154 } else if (base->is_Load() || 1155 base->is_DecodeN() && base->in(1)->is_Load()) { 1156 // Eliminate the load of boxed value for integer types from the cache 1157 // array by deriving the value from the index into the array. 1158 // Capture the offset of the load and then reverse the computation. 1159 1160 // Get LoadN node which loads a boxing object from 'cache' array. 1161 if (base->is_DecodeN()) { 1162 base = base->in(1); 1163 } 1164 if (!base->in(Address)->is_AddP()) { 1165 return NULL; // Complex address 1166 } 1167 AddPNode* address = base->in(Address)->as_AddP(); 1168 Node* cache_base = address->in(AddPNode::Base); 1169 if ((cache_base != NULL) && cache_base->is_DecodeN()) { 1170 // Get ConP node which is static 'cache' field. 1171 cache_base = cache_base->in(1); 1172 } 1173 if ((cache_base != NULL) && cache_base->is_Con()) { 1174 const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr(); 1175 if ((base_type != NULL) && base_type->is_autobox_cache()) { 1176 Node* elements[4]; 1177 int shift = exact_log2(type2aelembytes(T_OBJECT)); 1178 int count = address->unpack_offsets(elements, ARRAY_SIZE(elements)); 1179 if ((count > 0) && elements[0]->is_Con() && 1180 ((count == 1) || 1181 (count == 2) && elements[1]->Opcode() == Op_LShiftX && 1182 elements[1]->in(2) == phase->intcon(shift))) { 1183 ciObjArray* array = base_type->const_oop()->as_obj_array(); 1184 // Fetch the box object cache[0] at the base of the array and get its value 1185 ciInstance* box = array->obj_at(0)->as_instance(); 1186 ciInstanceKlass* ik = box->klass()->as_instance_klass(); 1187 assert(ik->is_box_klass(), "sanity"); 1188 assert(ik->nof_nonstatic_fields() == 1, "change following code"); 1189 if (ik->nof_nonstatic_fields() == 1) { 1190 // This should be true nonstatic_field_at requires calling 1191 // nof_nonstatic_fields so check it anyway 1192 ciConstant c = box->field_value(ik->nonstatic_field_at(0)); 1193 BasicType bt = c.basic_type(); 1194 // Only integer types have boxing cache. 1195 assert(bt == T_BOOLEAN || bt == T_CHAR || 1196 bt == T_BYTE || bt == T_SHORT || 1197 bt == T_INT || bt == T_LONG, err_msg_res("wrong type = %s", type2name(bt))); 1198 jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int(); 1199 if (cache_low != (int)cache_low) { 1200 return NULL; // should not happen since cache is array indexed by value 1201 } 1202 jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift); 1203 if (offset != (int)offset) { 1204 return NULL; // should not happen since cache is array indexed by value 1205 } 1206 // Add up all the offsets making of the address of the load 1207 Node* result = elements[0]; 1208 for (int i = 1; i < count; i++) { 1209 result = phase->transform(new AddXNode(result, elements[i])); 1210 } 1211 // Remove the constant offset from the address and then 1212 result = phase->transform(new AddXNode(result, phase->MakeConX(-(int)offset))); 1213 // remove the scaling of the offset to recover the original index. 1214 if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) { 1215 // Peel the shift off directly but wrap it in a dummy node 1216 // since Ideal can't return existing nodes 1217 result = new RShiftXNode(result->in(1), phase->intcon(0)); 1218 } else if (result->is_Add() && result->in(2)->is_Con() && 1219 result->in(1)->Opcode() == Op_LShiftX && 1220 result->in(1)->in(2) == phase->intcon(shift)) { 1221 // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z) 1222 // but for boxing cache access we know that X<<Z will not overflow 1223 // (there is range check) so we do this optimizatrion by hand here. 1224 Node* add_con = new RShiftXNode(result->in(2), phase->intcon(shift)); 1225 result = new AddXNode(result->in(1)->in(1), phase->transform(add_con)); 1226 } else { 1227 result = new RShiftXNode(result, phase->intcon(shift)); 1228 } 1229 #ifdef _LP64 1230 if (bt != T_LONG) { 1231 result = new ConvL2INode(phase->transform(result)); 1232 } 1233 #else 1234 if (bt == T_LONG) { 1235 result = new ConvI2LNode(phase->transform(result)); 1236 } 1237 #endif 1238 // Boxing/unboxing can be done from signed & unsigned loads (e.g. LoadUB -> ... -> LoadB pair). 1239 // Need to preserve unboxing load type if it is unsigned. 1240 switch(this->Opcode()) { 1241 case Op_LoadUB: 1242 result = new AndINode(phase->transform(result), phase->intcon(0xFF)); 1243 break; 1244 case Op_LoadUS: 1245 result = new AndINode(phase->transform(result), phase->intcon(0xFFFF)); 1246 break; 1247 } 1248 return result; 1249 } 1250 } 1251 } 1252 } 1253 } 1254 return NULL; 1255 } 1256 1257 static bool stable_phi(PhiNode* phi, PhaseGVN *phase) { 1258 Node* region = phi->in(0); 1259 if (region == NULL) { 1260 return false; // Wait stable graph 1261 } 1262 uint cnt = phi->req(); 1263 for (uint i = 1; i < cnt; i++) { 1264 Node* rc = region->in(i); 1265 if (rc == NULL || phase->type(rc) == Type::TOP) 1266 return false; // Wait stable graph 1267 Node* in = phi->in(i); 1268 if (in == NULL || phase->type(in) == Type::TOP) 1269 return false; // Wait stable graph 1270 } 1271 return true; 1272 } 1273 //------------------------------split_through_phi------------------------------ 1274 // Split instance or boxed field load through Phi. 1275 Node *LoadNode::split_through_phi(PhaseGVN *phase) { 1276 Node* mem = in(Memory); 1277 Node* address = in(Address); 1278 const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr(); 1279 1280 assert((t_oop != NULL) && 1281 (t_oop->is_known_instance_field() || 1282 t_oop->is_ptr_to_boxed_value()), "invalide conditions"); 1283 1284 Compile* C = phase->C; 1285 intptr_t ignore = 0; 1286 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore); 1287 bool base_is_phi = (base != NULL) && base->is_Phi(); 1288 bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() && 1289 (base != NULL) && (base == address->in(AddPNode::Base)) && 1290 phase->type(base)->higher_equal(TypePtr::NOTNULL); 1291 1292 if (!((mem->is_Phi() || base_is_phi) && 1293 (load_boxed_values || t_oop->is_known_instance_field()))) { 1294 return NULL; // memory is not Phi 1295 } 1296 1297 if (mem->is_Phi()) { 1298 if (!stable_phi(mem->as_Phi(), phase)) { 1299 return NULL; // Wait stable graph 1300 } 1301 uint cnt = mem->req(); 1302 // Check for loop invariant memory. 1303 if (cnt == 3) { 1304 for (uint i = 1; i < cnt; i++) { 1305 Node* in = mem->in(i); 1306 Node* m = optimize_memory_chain(in, t_oop, this, phase); 1307 if (m == mem) { 1308 set_req(Memory, mem->in(cnt - i)); 1309 return this; // made change 1310 } 1311 } 1312 } 1313 } 1314 if (base_is_phi) { 1315 if (!stable_phi(base->as_Phi(), phase)) { 1316 return NULL; // Wait stable graph 1317 } 1318 uint cnt = base->req(); 1319 // Check for loop invariant memory. 1320 if (cnt == 3) { 1321 for (uint i = 1; i < cnt; i++) { 1322 if (base->in(i) == base) { 1323 return NULL; // Wait stable graph 1324 } 1325 } 1326 } 1327 } 1328 1329 bool load_boxed_phi = load_boxed_values && base_is_phi && (base->in(0) == mem->in(0)); 1330 1331 // Split through Phi (see original code in loopopts.cpp). 1332 assert(C->have_alias_type(t_oop), "instance should have alias type"); 1333 1334 // Do nothing here if Identity will find a value 1335 // (to avoid infinite chain of value phis generation). 1336 if (!phase->eqv(this, this->Identity(phase))) 1337 return NULL; 1338 1339 // Select Region to split through. 1340 Node* region; 1341 if (!base_is_phi) { 1342 assert(mem->is_Phi(), "sanity"); 1343 region = mem->in(0); 1344 // Skip if the region dominates some control edge of the address. 1345 if (!MemNode::all_controls_dominate(address, region)) 1346 return NULL; 1347 } else if (!mem->is_Phi()) { 1348 assert(base_is_phi, "sanity"); 1349 region = base->in(0); 1350 // Skip if the region dominates some control edge of the memory. 1351 if (!MemNode::all_controls_dominate(mem, region)) 1352 return NULL; 1353 } else if (base->in(0) != mem->in(0)) { 1354 assert(base_is_phi && mem->is_Phi(), "sanity"); 1355 if (MemNode::all_controls_dominate(mem, base->in(0))) { 1356 region = base->in(0); 1357 } else if (MemNode::all_controls_dominate(address, mem->in(0))) { 1358 region = mem->in(0); 1359 } else { 1360 return NULL; // complex graph 1361 } 1362 } else { 1363 assert(base->in(0) == mem->in(0), "sanity"); 1364 region = mem->in(0); 1365 } 1366 1367 const Type* this_type = this->bottom_type(); 1368 int this_index = C->get_alias_index(t_oop); 1369 int this_offset = t_oop->offset(); 1370 int this_iid = t_oop->instance_id(); 1371 if (!t_oop->is_known_instance() && load_boxed_values) { 1372 // Use _idx of address base for boxed values. 1373 this_iid = base->_idx; 1374 } 1375 PhaseIterGVN* igvn = phase->is_IterGVN(); 1376 Node* phi = new PhiNode(region, this_type, NULL, this_iid, this_index, this_offset); 1377 for (uint i = 1; i < region->req(); i++) { 1378 Node* x; 1379 Node* the_clone = NULL; 1380 if (region->in(i) == C->top()) { 1381 x = C->top(); // Dead path? Use a dead data op 1382 } else { 1383 x = this->clone(); // Else clone up the data op 1384 the_clone = x; // Remember for possible deletion. 1385 // Alter data node to use pre-phi inputs 1386 if (this->in(0) == region) { 1387 x->set_req(0, region->in(i)); 1388 } else { 1389 x->set_req(0, NULL); 1390 } 1391 if (mem->is_Phi() && (mem->in(0) == region)) { 1392 x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone. 1393 } 1394 if (address->is_Phi() && address->in(0) == region) { 1395 x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone 1396 } 1397 if (base_is_phi && (base->in(0) == region)) { 1398 Node* base_x = base->in(i); // Clone address for loads from boxed objects. 1399 Node* adr_x = phase->transform(new AddPNode(base_x,base_x,address->in(AddPNode::Offset))); 1400 x->set_req(Address, adr_x); 1401 } 1402 } 1403 // Check for a 'win' on some paths 1404 const Type *t = x->Value(igvn); 1405 1406 bool singleton = t->singleton(); 1407 1408 // See comments in PhaseIdealLoop::split_thru_phi(). 1409 if (singleton && t == Type::TOP) { 1410 singleton &= region->is_Loop() && (i != LoopNode::EntryControl); 1411 } 1412 1413 if (singleton) { 1414 x = igvn->makecon(t); 1415 } else { 1416 // We now call Identity to try to simplify the cloned node. 1417 // Note that some Identity methods call phase->type(this). 1418 // Make sure that the type array is big enough for 1419 // our new node, even though we may throw the node away. 1420 // (This tweaking with igvn only works because x is a new node.) 1421 igvn->set_type(x, t); 1422 // If x is a TypeNode, capture any more-precise type permanently into Node 1423 // otherwise it will be not updated during igvn->transform since 1424 // igvn->type(x) is set to x->Value() already. 1425 x->raise_bottom_type(t); 1426 Node *y = x->Identity(igvn); 1427 if (y != x) { 1428 x = y; 1429 } else { 1430 y = igvn->hash_find_insert(x); 1431 if (y) { 1432 x = y; 1433 } else { 1434 // Else x is a new node we are keeping 1435 // We do not need register_new_node_with_optimizer 1436 // because set_type has already been called. 1437 igvn->_worklist.push(x); 1438 } 1439 } 1440 } 1441 if (x != the_clone && the_clone != NULL) { 1442 igvn->remove_dead_node(the_clone); 1443 } 1444 phi->set_req(i, x); 1445 } 1446 // Record Phi 1447 igvn->register_new_node_with_optimizer(phi); 1448 return phi; 1449 } 1450 1451 //------------------------------Ideal------------------------------------------ 1452 // If the load is from Field memory and the pointer is non-null, it might be possible to 1453 // zero out the control input. 1454 // If the offset is constant and the base is an object allocation, 1455 // try to hook me up to the exact initializing store. 1456 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1457 Node* p = MemNode::Ideal_common(phase, can_reshape); 1458 if (p) return (p == NodeSentinel) ? NULL : p; 1459 1460 Node* ctrl = in(MemNode::Control); 1461 Node* address = in(MemNode::Address); 1462 bool progress = false; 1463 1464 // Skip up past a SafePoint control. Cannot do this for Stores because 1465 // pointer stores & cardmarks must stay on the same side of a SafePoint. 1466 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint && 1467 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw ) { 1468 ctrl = ctrl->in(0); 1469 set_req(MemNode::Control,ctrl); 1470 progress = true; 1471 } 1472 1473 intptr_t ignore = 0; 1474 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore); 1475 if (base != NULL 1476 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) { 1477 // Check for useless control edge in some common special cases 1478 if (in(MemNode::Control) != NULL 1479 && can_remove_control() 1480 && phase->type(base)->higher_equal(TypePtr::NOTNULL) 1481 && all_controls_dominate(base, phase->C->start())) { 1482 // A method-invariant, non-null address (constant or 'this' argument). 1483 set_req(MemNode::Control, NULL); 1484 progress = true; 1485 } 1486 } 1487 1488 Node* mem = in(MemNode::Memory); 1489 const TypePtr *addr_t = phase->type(address)->isa_ptr(); 1490 1491 if (can_reshape && (addr_t != NULL)) { 1492 // try to optimize our memory input 1493 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase); 1494 if (opt_mem != mem) { 1495 set_req(MemNode::Memory, opt_mem); 1496 if (phase->type( opt_mem ) == Type::TOP) return NULL; 1497 return this; 1498 } 1499 const TypeOopPtr *t_oop = addr_t->isa_oopptr(); 1500 if ((t_oop != NULL) && 1501 (t_oop->is_known_instance_field() || 1502 t_oop->is_ptr_to_boxed_value())) { 1503 PhaseIterGVN *igvn = phase->is_IterGVN(); 1504 if (igvn != NULL && igvn->_worklist.member(opt_mem)) { 1505 // Delay this transformation until memory Phi is processed. 1506 phase->is_IterGVN()->_worklist.push(this); 1507 return NULL; 1508 } 1509 // Split instance field load through Phi. 1510 Node* result = split_through_phi(phase); 1511 if (result != NULL) return result; 1512 1513 if (t_oop->is_ptr_to_boxed_value()) { 1514 Node* result = eliminate_autobox(phase); 1515 if (result != NULL) return result; 1516 } 1517 } 1518 } 1519 1520 // Is there a dominating load that loads the same value? Leave 1521 // anything that is not a load of a field/array element (like 1522 // barriers etc.) alone 1523 if (in(0) != NULL && adr_type() != TypeRawPtr::BOTTOM && can_reshape) { 1524 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) { 1525 Node *use = mem->fast_out(i); 1526 if (use != this && 1527 use->Opcode() == Opcode() && 1528 use->in(0) != NULL && 1529 use->in(0) != in(0) && 1530 use->in(Address) == in(Address)) { 1531 Node* ctl = in(0); 1532 for (int i = 0; i < 10 && ctl != NULL; i++) { 1533 ctl = IfNode::up_one_dom(ctl); 1534 if (ctl == use->in(0)) { 1535 set_req(0, use->in(0)); 1536 return this; 1537 } 1538 } 1539 } 1540 } 1541 } 1542 1543 // Check for prior store with a different base or offset; make Load 1544 // independent. Skip through any number of them. Bail out if the stores 1545 // are in an endless dead cycle and report no progress. This is a key 1546 // transform for Reflection. However, if after skipping through the Stores 1547 // we can't then fold up against a prior store do NOT do the transform as 1548 // this amounts to using the 'Oracle' model of aliasing. It leaves the same 1549 // array memory alive twice: once for the hoisted Load and again after the 1550 // bypassed Store. This situation only works if EVERYBODY who does 1551 // anti-dependence work knows how to bypass. I.e. we need all 1552 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is 1553 // the alias index stuff. So instead, peek through Stores and IFF we can 1554 // fold up, do so. 1555 Node* prev_mem = find_previous_store(phase); 1556 if (prev_mem != NULL) { 1557 Node* value = can_see_arraycopy_value(prev_mem, phase); 1558 if (value != NULL) { 1559 return value; 1560 } 1561 } 1562 // Steps (a), (b): Walk past independent stores to find an exact match. 1563 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) { 1564 // (c) See if we can fold up on the spot, but don't fold up here. 1565 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or 1566 // just return a prior value, which is done by Identity calls. 1567 if (can_see_stored_value(prev_mem, phase)) { 1568 // Make ready for step (d): 1569 set_req(MemNode::Memory, prev_mem); 1570 return this; 1571 } 1572 } 1573 1574 return progress ? this : NULL; 1575 } 1576 1577 // Helper to recognize certain Klass fields which are invariant across 1578 // some group of array types (e.g., int[] or all T[] where T < Object). 1579 const Type* 1580 LoadNode::load_array_final_field(const TypeKlassPtr *tkls, 1581 ciKlass* klass) const { 1582 if (tkls->offset() == in_bytes(Klass::modifier_flags_offset())) { 1583 // The field is Klass::_modifier_flags. Return its (constant) value. 1584 // (Folds up the 2nd indirection in aClassConstant.getModifiers().) 1585 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags"); 1586 return TypeInt::make(klass->modifier_flags()); 1587 } 1588 if (tkls->offset() == in_bytes(Klass::access_flags_offset())) { 1589 // The field is Klass::_access_flags. Return its (constant) value. 1590 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).) 1591 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags"); 1592 return TypeInt::make(klass->access_flags()); 1593 } 1594 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) { 1595 // The field is Klass::_layout_helper. Return its constant value if known. 1596 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper"); 1597 return TypeInt::make(klass->layout_helper()); 1598 } 1599 1600 // No match. 1601 return NULL; 1602 } 1603 1604 // Try to constant-fold a stable array element. 1605 static const Type* fold_stable_ary_elem(const TypeAryPtr* ary, int off, BasicType loadbt) { 1606 assert(ary->const_oop(), "array should be constant"); 1607 assert(ary->is_stable(), "array should be stable"); 1608 1609 // Decode the results of GraphKit::array_element_address. 1610 ciArray* aobj = ary->const_oop()->as_array(); 1611 ciConstant con = aobj->element_value_by_offset(off); 1612 1613 if (con.basic_type() != T_ILLEGAL && !con.is_null_or_zero()) { 1614 const Type* con_type = Type::make_from_constant(con); 1615 if (con_type != NULL) { 1616 if (con_type->isa_aryptr()) { 1617 // Join with the array element type, in case it is also stable. 1618 int dim = ary->stable_dimension(); 1619 con_type = con_type->is_aryptr()->cast_to_stable(true, dim-1); 1620 } 1621 if (loadbt == T_NARROWOOP && con_type->isa_oopptr()) { 1622 con_type = con_type->make_narrowoop(); 1623 } 1624 #ifndef PRODUCT 1625 if (TraceIterativeGVN) { 1626 tty->print("FoldStableValues: array element [off=%d]: con_type=", off); 1627 con_type->dump(); tty->cr(); 1628 } 1629 #endif //PRODUCT 1630 return con_type; 1631 } 1632 } 1633 return NULL; 1634 } 1635 1636 //------------------------------Value----------------------------------------- 1637 const Type *LoadNode::Value( PhaseTransform *phase ) const { 1638 // Either input is TOP ==> the result is TOP 1639 Node* mem = in(MemNode::Memory); 1640 const Type *t1 = phase->type(mem); 1641 if (t1 == Type::TOP) return Type::TOP; 1642 Node* adr = in(MemNode::Address); 1643 const TypePtr* tp = phase->type(adr)->isa_ptr(); 1644 if (tp == NULL || tp->empty()) return Type::TOP; 1645 int off = tp->offset(); 1646 assert(off != Type::OffsetTop, "case covered by TypePtr::empty"); 1647 Compile* C = phase->C; 1648 1649 // Try to guess loaded type from pointer type 1650 if (tp->isa_aryptr()) { 1651 const TypeAryPtr* ary = tp->is_aryptr(); 1652 const Type* t = ary->elem(); 1653 1654 // Determine whether the reference is beyond the header or not, by comparing 1655 // the offset against the offset of the start of the array's data. 1656 // Different array types begin at slightly different offsets (12 vs. 16). 1657 // We choose T_BYTE as an example base type that is least restrictive 1658 // as to alignment, which will therefore produce the smallest 1659 // possible base offset. 1660 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE); 1661 const bool off_beyond_header = ((uint)off >= (uint)min_base_off); 1662 1663 // Try to constant-fold a stable array element. 1664 if (FoldStableValues && ary->is_stable() && ary->const_oop() != NULL) { 1665 // Make sure the reference is not into the header and the offset is constant 1666 if (off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) { 1667 const Type* con_type = fold_stable_ary_elem(ary, off, memory_type()); 1668 if (con_type != NULL) { 1669 return con_type; 1670 } 1671 } 1672 } 1673 1674 // Don't do this for integer types. There is only potential profit if 1675 // the element type t is lower than _type; that is, for int types, if _type is 1676 // more restrictive than t. This only happens here if one is short and the other 1677 // char (both 16 bits), and in those cases we've made an intentional decision 1678 // to use one kind of load over the other. See AndINode::Ideal and 4965907. 1679 // Also, do not try to narrow the type for a LoadKlass, regardless of offset. 1680 // 1681 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8)) 1682 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier 1683 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been 1684 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed, 1685 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any. 1686 // In fact, that could have been the original type of p1, and p1 could have 1687 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the 1688 // expression (LShiftL quux 3) independently optimized to the constant 8. 1689 if ((t->isa_int() == NULL) && (t->isa_long() == NULL) 1690 && (_type->isa_vect() == NULL) 1691 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) { 1692 // t might actually be lower than _type, if _type is a unique 1693 // concrete subclass of abstract class t. 1694 if (off_beyond_header) { // is the offset beyond the header? 1695 const Type* jt = t->join_speculative(_type); 1696 // In any case, do not allow the join, per se, to empty out the type. 1697 if (jt->empty() && !t->empty()) { 1698 // This can happen if a interface-typed array narrows to a class type. 1699 jt = _type; 1700 } 1701 #ifdef ASSERT 1702 if (phase->C->eliminate_boxing() && adr->is_AddP()) { 1703 // The pointers in the autobox arrays are always non-null 1704 Node* base = adr->in(AddPNode::Base); 1705 if ((base != NULL) && base->is_DecodeN()) { 1706 // Get LoadN node which loads IntegerCache.cache field 1707 base = base->in(1); 1708 } 1709 if ((base != NULL) && base->is_Con()) { 1710 const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr(); 1711 if ((base_type != NULL) && base_type->is_autobox_cache()) { 1712 // It could be narrow oop 1713 assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity"); 1714 } 1715 } 1716 } 1717 #endif 1718 return jt; 1719 } 1720 } 1721 } else if (tp->base() == Type::InstPtr) { 1722 ciEnv* env = C->env(); 1723 const TypeInstPtr* tinst = tp->is_instptr(); 1724 ciKlass* klass = tinst->klass(); 1725 assert( off != Type::OffsetBot || 1726 // arrays can be cast to Objects 1727 tp->is_oopptr()->klass()->is_java_lang_Object() || 1728 // unsafe field access may not have a constant offset 1729 C->has_unsafe_access(), 1730 "Field accesses must be precise" ); 1731 // For oop loads, we expect the _type to be precise 1732 if (klass == env->String_klass() && 1733 adr->is_AddP() && off != Type::OffsetBot) { 1734 // For constant Strings treat the final fields as compile time constants. 1735 Node* base = adr->in(AddPNode::Base); 1736 const TypeOopPtr* t = phase->type(base)->isa_oopptr(); 1737 if (t != NULL && t->singleton()) { 1738 ciField* field = env->String_klass()->get_field_by_offset(off, false); 1739 if (field != NULL && field->is_final()) { 1740 ciObject* string = t->const_oop(); 1741 ciConstant constant = string->as_instance()->field_value(field); 1742 if (constant.basic_type() == T_INT) { 1743 return TypeInt::make(constant.as_int()); 1744 } else if (constant.basic_type() == T_ARRAY) { 1745 if (adr->bottom_type()->is_ptr_to_narrowoop()) { 1746 return TypeNarrowOop::make_from_constant(constant.as_object(), true); 1747 } else { 1748 return TypeOopPtr::make_from_constant(constant.as_object(), true); 1749 } 1750 } 1751 } 1752 } 1753 } 1754 // Optimizations for constant objects 1755 ciObject* const_oop = tinst->const_oop(); 1756 if (const_oop != NULL) { 1757 // For constant Boxed value treat the target field as a compile time constant. 1758 if (tinst->is_ptr_to_boxed_value()) { 1759 return tinst->get_const_boxed_value(); 1760 } else 1761 // For constant CallSites treat the target field as a compile time constant. 1762 if (const_oop->is_call_site()) { 1763 ciCallSite* call_site = const_oop->as_call_site(); 1764 ciField* field = call_site->klass()->as_instance_klass()->get_field_by_offset(off, /*is_static=*/ false); 1765 if (field != NULL && field->is_call_site_target()) { 1766 ciMethodHandle* target = call_site->get_target(); 1767 if (target != NULL) { // just in case 1768 ciConstant constant(T_OBJECT, target); 1769 const Type* t; 1770 if (adr->bottom_type()->is_ptr_to_narrowoop()) { 1771 t = TypeNarrowOop::make_from_constant(constant.as_object(), true); 1772 } else { 1773 t = TypeOopPtr::make_from_constant(constant.as_object(), true); 1774 } 1775 // Add a dependence for invalidation of the optimization. 1776 if (!call_site->is_constant_call_site()) { 1777 C->dependencies()->assert_call_site_target_value(call_site, target); 1778 } 1779 return t; 1780 } 1781 } 1782 } 1783 } 1784 } else if (tp->base() == Type::KlassPtr) { 1785 assert( off != Type::OffsetBot || 1786 // arrays can be cast to Objects 1787 tp->is_klassptr()->klass()->is_java_lang_Object() || 1788 // also allow array-loading from the primary supertype 1789 // array during subtype checks 1790 Opcode() == Op_LoadKlass, 1791 "Field accesses must be precise" ); 1792 // For klass/static loads, we expect the _type to be precise 1793 } 1794 1795 const TypeKlassPtr *tkls = tp->isa_klassptr(); 1796 if (tkls != NULL && !StressReflectiveCode) { 1797 ciKlass* klass = tkls->klass(); 1798 if (klass->is_loaded() && tkls->klass_is_exact()) { 1799 // We are loading a field from a Klass metaobject whose identity 1800 // is known at compile time (the type is "exact" or "precise"). 1801 // Check for fields we know are maintained as constants by the VM. 1802 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) { 1803 // The field is Klass::_super_check_offset. Return its (constant) value. 1804 // (Folds up type checking code.) 1805 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset"); 1806 return TypeInt::make(klass->super_check_offset()); 1807 } 1808 // Compute index into primary_supers array 1809 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*); 1810 // Check for overflowing; use unsigned compare to handle the negative case. 1811 if( depth < ciKlass::primary_super_limit() ) { 1812 // The field is an element of Klass::_primary_supers. Return its (constant) value. 1813 // (Folds up type checking code.) 1814 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers"); 1815 ciKlass *ss = klass->super_of_depth(depth); 1816 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR; 1817 } 1818 const Type* aift = load_array_final_field(tkls, klass); 1819 if (aift != NULL) return aift; 1820 if (tkls->offset() == in_bytes(Klass::java_mirror_offset())) { 1821 // The field is Klass::_java_mirror. Return its (constant) value. 1822 // (Folds up the 2nd indirection in anObjConstant.getClass().) 1823 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror"); 1824 return TypeInstPtr::make(klass->java_mirror()); 1825 } 1826 } 1827 1828 // We can still check if we are loading from the primary_supers array at a 1829 // shallow enough depth. Even though the klass is not exact, entries less 1830 // than or equal to its super depth are correct. 1831 if (klass->is_loaded() ) { 1832 ciType *inner = klass; 1833 while( inner->is_obj_array_klass() ) 1834 inner = inner->as_obj_array_klass()->base_element_type(); 1835 if( inner->is_instance_klass() && 1836 !inner->as_instance_klass()->flags().is_interface() ) { 1837 // Compute index into primary_supers array 1838 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*); 1839 // Check for overflowing; use unsigned compare to handle the negative case. 1840 if( depth < ciKlass::primary_super_limit() && 1841 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case 1842 // The field is an element of Klass::_primary_supers. Return its (constant) value. 1843 // (Folds up type checking code.) 1844 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers"); 1845 ciKlass *ss = klass->super_of_depth(depth); 1846 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR; 1847 } 1848 } 1849 } 1850 1851 // If the type is enough to determine that the thing is not an array, 1852 // we can give the layout_helper a positive interval type. 1853 // This will help short-circuit some reflective code. 1854 if (tkls->offset() == in_bytes(Klass::layout_helper_offset()) 1855 && !klass->is_array_klass() // not directly typed as an array 1856 && !klass->is_interface() // specifically not Serializable & Cloneable 1857 && !klass->is_java_lang_Object() // not the supertype of all T[] 1858 ) { 1859 // Note: When interfaces are reliable, we can narrow the interface 1860 // test to (klass != Serializable && klass != Cloneable). 1861 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper"); 1862 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false); 1863 // The key property of this type is that it folds up tests 1864 // for array-ness, since it proves that the layout_helper is positive. 1865 // Thus, a generic value like the basic object layout helper works fine. 1866 return TypeInt::make(min_size, max_jint, Type::WidenMin); 1867 } 1868 } 1869 1870 // If we are loading from a freshly-allocated object, produce a zero, 1871 // if the load is provably beyond the header of the object. 1872 // (Also allow a variable load from a fresh array to produce zero.) 1873 const TypeOopPtr *tinst = tp->isa_oopptr(); 1874 bool is_instance = (tinst != NULL) && tinst->is_known_instance_field(); 1875 bool is_boxed_value = (tinst != NULL) && tinst->is_ptr_to_boxed_value(); 1876 if (ReduceFieldZeroing || is_instance || is_boxed_value) { 1877 Node* value = can_see_stored_value(mem,phase); 1878 if (value != NULL && value->is_Con()) { 1879 assert(value->bottom_type()->higher_equal(_type),"sanity"); 1880 return value->bottom_type(); 1881 } 1882 } 1883 1884 if (is_instance) { 1885 // If we have an instance type and our memory input is the 1886 // programs's initial memory state, there is no matching store, 1887 // so just return a zero of the appropriate type 1888 Node *mem = in(MemNode::Memory); 1889 if (mem->is_Parm() && mem->in(0)->is_Start()) { 1890 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm"); 1891 return Type::get_zero_type(_type->basic_type()); 1892 } 1893 } 1894 return _type; 1895 } 1896 1897 //------------------------------match_edge------------------------------------- 1898 // Do we Match on this edge index or not? Match only the address. 1899 uint LoadNode::match_edge(uint idx) const { 1900 return idx == MemNode::Address; 1901 } 1902 1903 //--------------------------LoadBNode::Ideal-------------------------------------- 1904 // 1905 // If the previous store is to the same address as this load, 1906 // and the value stored was larger than a byte, replace this load 1907 // with the value stored truncated to a byte. If no truncation is 1908 // needed, the replacement is done in LoadNode::Identity(). 1909 // 1910 Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1911 Node* mem = in(MemNode::Memory); 1912 Node* value = can_see_stored_value(mem,phase); 1913 if( value && !phase->type(value)->higher_equal( _type ) ) { 1914 Node *result = phase->transform( new LShiftINode(value, phase->intcon(24)) ); 1915 return new RShiftINode(result, phase->intcon(24)); 1916 } 1917 // Identity call will handle the case where truncation is not needed. 1918 return LoadNode::Ideal(phase, can_reshape); 1919 } 1920 1921 const Type* LoadBNode::Value(PhaseTransform *phase) const { 1922 Node* mem = in(MemNode::Memory); 1923 Node* value = can_see_stored_value(mem,phase); 1924 if (value != NULL && value->is_Con() && 1925 !value->bottom_type()->higher_equal(_type)) { 1926 // If the input to the store does not fit with the load's result type, 1927 // it must be truncated. We can't delay until Ideal call since 1928 // a singleton Value is needed for split_thru_phi optimization. 1929 int con = value->get_int(); 1930 return TypeInt::make((con << 24) >> 24); 1931 } 1932 return LoadNode::Value(phase); 1933 } 1934 1935 //--------------------------LoadUBNode::Ideal------------------------------------- 1936 // 1937 // If the previous store is to the same address as this load, 1938 // and the value stored was larger than a byte, replace this load 1939 // with the value stored truncated to a byte. If no truncation is 1940 // needed, the replacement is done in LoadNode::Identity(). 1941 // 1942 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) { 1943 Node* mem = in(MemNode::Memory); 1944 Node* value = can_see_stored_value(mem, phase); 1945 if (value && !phase->type(value)->higher_equal(_type)) 1946 return new AndINode(value, phase->intcon(0xFF)); 1947 // Identity call will handle the case where truncation is not needed. 1948 return LoadNode::Ideal(phase, can_reshape); 1949 } 1950 1951 const Type* LoadUBNode::Value(PhaseTransform *phase) const { 1952 Node* mem = in(MemNode::Memory); 1953 Node* value = can_see_stored_value(mem,phase); 1954 if (value != NULL && value->is_Con() && 1955 !value->bottom_type()->higher_equal(_type)) { 1956 // If the input to the store does not fit with the load's result type, 1957 // it must be truncated. We can't delay until Ideal call since 1958 // a singleton Value is needed for split_thru_phi optimization. 1959 int con = value->get_int(); 1960 return TypeInt::make(con & 0xFF); 1961 } 1962 return LoadNode::Value(phase); 1963 } 1964 1965 //--------------------------LoadUSNode::Ideal------------------------------------- 1966 // 1967 // If the previous store is to the same address as this load, 1968 // and the value stored was larger than a char, replace this load 1969 // with the value stored truncated to a char. If no truncation is 1970 // needed, the replacement is done in LoadNode::Identity(). 1971 // 1972 Node *LoadUSNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1973 Node* mem = in(MemNode::Memory); 1974 Node* value = can_see_stored_value(mem,phase); 1975 if( value && !phase->type(value)->higher_equal( _type ) ) 1976 return new AndINode(value,phase->intcon(0xFFFF)); 1977 // Identity call will handle the case where truncation is not needed. 1978 return LoadNode::Ideal(phase, can_reshape); 1979 } 1980 1981 const Type* LoadUSNode::Value(PhaseTransform *phase) const { 1982 Node* mem = in(MemNode::Memory); 1983 Node* value = can_see_stored_value(mem,phase); 1984 if (value != NULL && value->is_Con() && 1985 !value->bottom_type()->higher_equal(_type)) { 1986 // If the input to the store does not fit with the load's result type, 1987 // it must be truncated. We can't delay until Ideal call since 1988 // a singleton Value is needed for split_thru_phi optimization. 1989 int con = value->get_int(); 1990 return TypeInt::make(con & 0xFFFF); 1991 } 1992 return LoadNode::Value(phase); 1993 } 1994 1995 //--------------------------LoadSNode::Ideal-------------------------------------- 1996 // 1997 // If the previous store is to the same address as this load, 1998 // and the value stored was larger than a short, replace this load 1999 // with the value stored truncated to a short. If no truncation is 2000 // needed, the replacement is done in LoadNode::Identity(). 2001 // 2002 Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2003 Node* mem = in(MemNode::Memory); 2004 Node* value = can_see_stored_value(mem,phase); 2005 if( value && !phase->type(value)->higher_equal( _type ) ) { 2006 Node *result = phase->transform( new LShiftINode(value, phase->intcon(16)) ); 2007 return new RShiftINode(result, phase->intcon(16)); 2008 } 2009 // Identity call will handle the case where truncation is not needed. 2010 return LoadNode::Ideal(phase, can_reshape); 2011 } 2012 2013 const Type* LoadSNode::Value(PhaseTransform *phase) const { 2014 Node* mem = in(MemNode::Memory); 2015 Node* value = can_see_stored_value(mem,phase); 2016 if (value != NULL && value->is_Con() && 2017 !value->bottom_type()->higher_equal(_type)) { 2018 // If the input to the store does not fit with the load's result type, 2019 // it must be truncated. We can't delay until Ideal call since 2020 // a singleton Value is needed for split_thru_phi optimization. 2021 int con = value->get_int(); 2022 return TypeInt::make((con << 16) >> 16); 2023 } 2024 return LoadNode::Value(phase); 2025 } 2026 2027 //============================================================================= 2028 //----------------------------LoadKlassNode::make------------------------------ 2029 // Polymorphic factory method: 2030 Node* LoadKlassNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* at, const TypeKlassPtr* tk) { 2031 // sanity check the alias category against the created node type 2032 const TypePtr *adr_type = adr->bottom_type()->isa_ptr(); 2033 assert(adr_type != NULL, "expecting TypeKlassPtr"); 2034 #ifdef _LP64 2035 if (adr_type->is_ptr_to_narrowklass()) { 2036 assert(UseCompressedClassPointers, "no compressed klasses"); 2037 Node* load_klass = gvn.transform(new LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowklass(), MemNode::unordered)); 2038 return new DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr()); 2039 } 2040 #endif 2041 assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop"); 2042 return new LoadKlassNode(ctl, mem, adr, at, tk, MemNode::unordered); 2043 } 2044 2045 //------------------------------Value------------------------------------------ 2046 const Type *LoadKlassNode::Value( PhaseTransform *phase ) const { 2047 return klass_value_common(phase); 2048 } 2049 2050 // In most cases, LoadKlassNode does not have the control input set. If the control 2051 // input is set, it must not be removed (by LoadNode::Ideal()). 2052 bool LoadKlassNode::can_remove_control() const { 2053 return false; 2054 } 2055 2056 const Type *LoadNode::klass_value_common( PhaseTransform *phase ) const { 2057 // Either input is TOP ==> the result is TOP 2058 const Type *t1 = phase->type( in(MemNode::Memory) ); 2059 if (t1 == Type::TOP) return Type::TOP; 2060 Node *adr = in(MemNode::Address); 2061 const Type *t2 = phase->type( adr ); 2062 if (t2 == Type::TOP) return Type::TOP; 2063 const TypePtr *tp = t2->is_ptr(); 2064 if (TypePtr::above_centerline(tp->ptr()) || 2065 tp->ptr() == TypePtr::Null) return Type::TOP; 2066 2067 // Return a more precise klass, if possible 2068 const TypeInstPtr *tinst = tp->isa_instptr(); 2069 if (tinst != NULL) { 2070 ciInstanceKlass* ik = tinst->klass()->as_instance_klass(); 2071 int offset = tinst->offset(); 2072 if (ik == phase->C->env()->Class_klass() 2073 && (offset == java_lang_Class::klass_offset_in_bytes() || 2074 offset == java_lang_Class::array_klass_offset_in_bytes())) { 2075 // We are loading a special hidden field from a Class mirror object, 2076 // the field which points to the VM's Klass metaobject. 2077 ciType* t = tinst->java_mirror_type(); 2078 // java_mirror_type returns non-null for compile-time Class constants. 2079 if (t != NULL) { 2080 // constant oop => constant klass 2081 if (offset == java_lang_Class::array_klass_offset_in_bytes()) { 2082 if (t->is_void()) { 2083 // We cannot create a void array. Since void is a primitive type return null 2084 // klass. Users of this result need to do a null check on the returned klass. 2085 return TypePtr::NULL_PTR; 2086 } 2087 return TypeKlassPtr::make(ciArrayKlass::make(t)); 2088 } 2089 if (!t->is_klass()) { 2090 // a primitive Class (e.g., int.class) has NULL for a klass field 2091 return TypePtr::NULL_PTR; 2092 } 2093 // (Folds up the 1st indirection in aClassConstant.getModifiers().) 2094 return TypeKlassPtr::make(t->as_klass()); 2095 } 2096 // non-constant mirror, so we can't tell what's going on 2097 } 2098 if( !ik->is_loaded() ) 2099 return _type; // Bail out if not loaded 2100 if (offset == oopDesc::klass_offset_in_bytes()) { 2101 if (tinst->klass_is_exact()) { 2102 return TypeKlassPtr::make(ik); 2103 } 2104 // See if we can become precise: no subklasses and no interface 2105 // (Note: We need to support verified interfaces.) 2106 if (!ik->is_interface() && !ik->has_subklass()) { 2107 //assert(!UseExactTypes, "this code should be useless with exact types"); 2108 // Add a dependence; if any subclass added we need to recompile 2109 if (!ik->is_final()) { 2110 // %%% should use stronger assert_unique_concrete_subtype instead 2111 phase->C->dependencies()->assert_leaf_type(ik); 2112 } 2113 // Return precise klass 2114 return TypeKlassPtr::make(ik); 2115 } 2116 2117 // Return root of possible klass 2118 return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/); 2119 } 2120 } 2121 2122 // Check for loading klass from an array 2123 const TypeAryPtr *tary = tp->isa_aryptr(); 2124 if( tary != NULL ) { 2125 ciKlass *tary_klass = tary->klass(); 2126 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP 2127 && tary->offset() == oopDesc::klass_offset_in_bytes()) { 2128 if (tary->klass_is_exact()) { 2129 return TypeKlassPtr::make(tary_klass); 2130 } 2131 ciArrayKlass *ak = tary->klass()->as_array_klass(); 2132 // If the klass is an object array, we defer the question to the 2133 // array component klass. 2134 if( ak->is_obj_array_klass() ) { 2135 assert( ak->is_loaded(), "" ); 2136 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass(); 2137 if( base_k->is_loaded() && base_k->is_instance_klass() ) { 2138 ciInstanceKlass* ik = base_k->as_instance_klass(); 2139 // See if we can become precise: no subklasses and no interface 2140 if (!ik->is_interface() && !ik->has_subklass()) { 2141 //assert(!UseExactTypes, "this code should be useless with exact types"); 2142 // Add a dependence; if any subclass added we need to recompile 2143 if (!ik->is_final()) { 2144 phase->C->dependencies()->assert_leaf_type(ik); 2145 } 2146 // Return precise array klass 2147 return TypeKlassPtr::make(ak); 2148 } 2149 } 2150 return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/); 2151 } else { // Found a type-array? 2152 //assert(!UseExactTypes, "this code should be useless with exact types"); 2153 assert( ak->is_type_array_klass(), "" ); 2154 return TypeKlassPtr::make(ak); // These are always precise 2155 } 2156 } 2157 } 2158 2159 // Check for loading klass from an array klass 2160 const TypeKlassPtr *tkls = tp->isa_klassptr(); 2161 if (tkls != NULL && !StressReflectiveCode) { 2162 ciKlass* klass = tkls->klass(); 2163 if( !klass->is_loaded() ) 2164 return _type; // Bail out if not loaded 2165 if( klass->is_obj_array_klass() && 2166 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) { 2167 ciKlass* elem = klass->as_obj_array_klass()->element_klass(); 2168 // // Always returning precise element type is incorrect, 2169 // // e.g., element type could be object and array may contain strings 2170 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0); 2171 2172 // The array's TypeKlassPtr was declared 'precise' or 'not precise' 2173 // according to the element type's subclassing. 2174 return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/); 2175 } 2176 if( klass->is_instance_klass() && tkls->klass_is_exact() && 2177 tkls->offset() == in_bytes(Klass::super_offset())) { 2178 ciKlass* sup = klass->as_instance_klass()->super(); 2179 // The field is Klass::_super. Return its (constant) value. 2180 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().) 2181 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR; 2182 } 2183 } 2184 2185 // Bailout case 2186 return LoadNode::Value(phase); 2187 } 2188 2189 //------------------------------Identity--------------------------------------- 2190 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k. 2191 // Also feed through the klass in Allocate(...klass...)._klass. 2192 Node* LoadKlassNode::Identity( PhaseTransform *phase ) { 2193 return klass_identity_common(phase); 2194 } 2195 2196 Node* LoadNode::klass_identity_common(PhaseTransform *phase ) { 2197 Node* x = LoadNode::Identity(phase); 2198 if (x != this) return x; 2199 2200 // Take apart the address into an oop and and offset. 2201 // Return 'this' if we cannot. 2202 Node* adr = in(MemNode::Address); 2203 intptr_t offset = 0; 2204 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 2205 if (base == NULL) return this; 2206 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr(); 2207 if (toop == NULL) return this; 2208 2209 // We can fetch the klass directly through an AllocateNode. 2210 // This works even if the klass is not constant (clone or newArray). 2211 if (offset == oopDesc::klass_offset_in_bytes()) { 2212 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase); 2213 if (allocated_klass != NULL) { 2214 return allocated_klass; 2215 } 2216 } 2217 2218 // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*. 2219 // See inline_native_Class_query for occurrences of these patterns. 2220 // Java Example: x.getClass().isAssignableFrom(y) 2221 // 2222 // This improves reflective code, often making the Class 2223 // mirror go completely dead. (Current exception: Class 2224 // mirrors may appear in debug info, but we could clean them out by 2225 // introducing a new debug info operator for Klass*.java_mirror). 2226 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass() 2227 && offset == java_lang_Class::klass_offset_in_bytes()) { 2228 // We are loading a special hidden field from a Class mirror, 2229 // the field which points to its Klass or ArrayKlass metaobject. 2230 if (base->is_Load()) { 2231 Node* adr2 = base->in(MemNode::Address); 2232 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr(); 2233 if (tkls != NULL && !tkls->empty() 2234 && (tkls->klass()->is_instance_klass() || 2235 tkls->klass()->is_array_klass()) 2236 && adr2->is_AddP() 2237 ) { 2238 int mirror_field = in_bytes(Klass::java_mirror_offset()); 2239 if (tkls->offset() == mirror_field) { 2240 return adr2->in(AddPNode::Base); 2241 } 2242 } 2243 } 2244 } 2245 2246 return this; 2247 } 2248 2249 2250 //------------------------------Value------------------------------------------ 2251 const Type *LoadNKlassNode::Value( PhaseTransform *phase ) const { 2252 const Type *t = klass_value_common(phase); 2253 if (t == Type::TOP) 2254 return t; 2255 2256 return t->make_narrowklass(); 2257 } 2258 2259 //------------------------------Identity--------------------------------------- 2260 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k. 2261 // Also feed through the klass in Allocate(...klass...)._klass. 2262 Node* LoadNKlassNode::Identity( PhaseTransform *phase ) { 2263 Node *x = klass_identity_common(phase); 2264 2265 const Type *t = phase->type( x ); 2266 if( t == Type::TOP ) return x; 2267 if( t->isa_narrowklass()) return x; 2268 assert (!t->isa_narrowoop(), "no narrow oop here"); 2269 2270 return phase->transform(new EncodePKlassNode(x, t->make_narrowklass())); 2271 } 2272 2273 //------------------------------Value----------------------------------------- 2274 const Type *LoadRangeNode::Value( PhaseTransform *phase ) const { 2275 // Either input is TOP ==> the result is TOP 2276 const Type *t1 = phase->type( in(MemNode::Memory) ); 2277 if( t1 == Type::TOP ) return Type::TOP; 2278 Node *adr = in(MemNode::Address); 2279 const Type *t2 = phase->type( adr ); 2280 if( t2 == Type::TOP ) return Type::TOP; 2281 const TypePtr *tp = t2->is_ptr(); 2282 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP; 2283 const TypeAryPtr *tap = tp->isa_aryptr(); 2284 if( !tap ) return _type; 2285 return tap->size(); 2286 } 2287 2288 //-------------------------------Ideal--------------------------------------- 2289 // Feed through the length in AllocateArray(...length...)._length. 2290 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2291 Node* p = MemNode::Ideal_common(phase, can_reshape); 2292 if (p) return (p == NodeSentinel) ? NULL : p; 2293 2294 // Take apart the address into an oop and and offset. 2295 // Return 'this' if we cannot. 2296 Node* adr = in(MemNode::Address); 2297 intptr_t offset = 0; 2298 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 2299 if (base == NULL) return NULL; 2300 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr(); 2301 if (tary == NULL) return NULL; 2302 2303 // We can fetch the length directly through an AllocateArrayNode. 2304 // This works even if the length is not constant (clone or newArray). 2305 if (offset == arrayOopDesc::length_offset_in_bytes()) { 2306 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase); 2307 if (alloc != NULL) { 2308 Node* allocated_length = alloc->Ideal_length(); 2309 Node* len = alloc->make_ideal_length(tary, phase); 2310 if (allocated_length != len) { 2311 // New CastII improves on this. 2312 return len; 2313 } 2314 } 2315 } 2316 2317 return NULL; 2318 } 2319 2320 //------------------------------Identity--------------------------------------- 2321 // Feed through the length in AllocateArray(...length...)._length. 2322 Node* LoadRangeNode::Identity( PhaseTransform *phase ) { 2323 Node* x = LoadINode::Identity(phase); 2324 if (x != this) return x; 2325 2326 // Take apart the address into an oop and and offset. 2327 // Return 'this' if we cannot. 2328 Node* adr = in(MemNode::Address); 2329 intptr_t offset = 0; 2330 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset); 2331 if (base == NULL) return this; 2332 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr(); 2333 if (tary == NULL) return this; 2334 2335 // We can fetch the length directly through an AllocateArrayNode. 2336 // This works even if the length is not constant (clone or newArray). 2337 if (offset == arrayOopDesc::length_offset_in_bytes()) { 2338 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase); 2339 if (alloc != NULL) { 2340 Node* allocated_length = alloc->Ideal_length(); 2341 // Do not allow make_ideal_length to allocate a CastII node. 2342 Node* len = alloc->make_ideal_length(tary, phase, false); 2343 if (allocated_length == len) { 2344 // Return allocated_length only if it would not be improved by a CastII. 2345 return allocated_length; 2346 } 2347 } 2348 } 2349 2350 return this; 2351 2352 } 2353 2354 //============================================================================= 2355 //---------------------------StoreNode::make----------------------------------- 2356 // Polymorphic factory method: 2357 StoreNode* StoreNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt, MemOrd mo) { 2358 assert((mo == unordered || mo == release), "unexpected"); 2359 Compile* C = gvn.C; 2360 assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw || 2361 ctl != NULL, "raw memory operations should have control edge"); 2362 2363 switch (bt) { 2364 case T_BOOLEAN: 2365 case T_BYTE: return new StoreBNode(ctl, mem, adr, adr_type, val, mo); 2366 case T_INT: return new StoreINode(ctl, mem, adr, adr_type, val, mo); 2367 case T_CHAR: 2368 case T_SHORT: return new StoreCNode(ctl, mem, adr, adr_type, val, mo); 2369 case T_LONG: return new StoreLNode(ctl, mem, adr, adr_type, val, mo); 2370 case T_FLOAT: return new StoreFNode(ctl, mem, adr, adr_type, val, mo); 2371 case T_DOUBLE: return new StoreDNode(ctl, mem, adr, adr_type, val, mo); 2372 case T_METADATA: 2373 case T_ADDRESS: 2374 case T_OBJECT: 2375 #ifdef _LP64 2376 if (adr->bottom_type()->is_ptr_to_narrowoop()) { 2377 val = gvn.transform(new EncodePNode(val, val->bottom_type()->make_narrowoop())); 2378 return new StoreNNode(ctl, mem, adr, adr_type, val, mo); 2379 } else if (adr->bottom_type()->is_ptr_to_narrowklass() || 2380 (UseCompressedClassPointers && val->bottom_type()->isa_klassptr() && 2381 adr->bottom_type()->isa_rawptr())) { 2382 val = gvn.transform(new EncodePKlassNode(val, val->bottom_type()->make_narrowklass())); 2383 return new StoreNKlassNode(ctl, mem, adr, adr_type, val, mo); 2384 } 2385 #endif 2386 { 2387 return new StorePNode(ctl, mem, adr, adr_type, val, mo); 2388 } 2389 } 2390 ShouldNotReachHere(); 2391 return (StoreNode*)NULL; 2392 } 2393 2394 StoreLNode* StoreLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) { 2395 bool require_atomic = true; 2396 return new StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic); 2397 } 2398 2399 StoreDNode* StoreDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) { 2400 bool require_atomic = true; 2401 return new StoreDNode(ctl, mem, adr, adr_type, val, mo, require_atomic); 2402 } 2403 2404 2405 //--------------------------bottom_type---------------------------------------- 2406 const Type *StoreNode::bottom_type() const { 2407 return Type::MEMORY; 2408 } 2409 2410 //------------------------------hash------------------------------------------- 2411 uint StoreNode::hash() const { 2412 // unroll addition of interesting fields 2413 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn); 2414 2415 // Since they are not commoned, do not hash them: 2416 return NO_HASH; 2417 } 2418 2419 //------------------------------Ideal------------------------------------------ 2420 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x). 2421 // When a store immediately follows a relevant allocation/initialization, 2422 // try to capture it into the initialization, or hoist it above. 2423 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2424 Node* p = MemNode::Ideal_common(phase, can_reshape); 2425 if (p) return (p == NodeSentinel) ? NULL : p; 2426 2427 Node* mem = in(MemNode::Memory); 2428 Node* address = in(MemNode::Address); 2429 2430 // Back-to-back stores to same address? Fold em up. Generally 2431 // unsafe if I have intervening uses... Also disallowed for StoreCM 2432 // since they must follow each StoreP operation. Redundant StoreCMs 2433 // are eliminated just before matching in final_graph_reshape. 2434 if (mem->is_Store() && mem->in(MemNode::Address)->eqv_uncast(address) && 2435 mem->Opcode() != Op_StoreCM) { 2436 // Looking at a dead closed cycle of memory? 2437 assert(mem != mem->in(MemNode::Memory), "dead loop in StoreNode::Ideal"); 2438 2439 assert(Opcode() == mem->Opcode() || 2440 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw, 2441 "no mismatched stores, except on raw memory"); 2442 2443 if (mem->outcnt() == 1 && // check for intervening uses 2444 mem->as_Store()->memory_size() <= this->memory_size()) { 2445 // If anybody other than 'this' uses 'mem', we cannot fold 'mem' away. 2446 // For example, 'mem' might be the final state at a conditional return. 2447 // Or, 'mem' might be used by some node which is live at the same time 2448 // 'this' is live, which might be unschedulable. So, require exactly 2449 // ONE user, the 'this' store, until such time as we clone 'mem' for 2450 // each of 'mem's uses (thus making the exactly-1-user-rule hold true). 2451 if (can_reshape) { // (%%% is this an anachronism?) 2452 set_req_X(MemNode::Memory, mem->in(MemNode::Memory), 2453 phase->is_IterGVN()); 2454 } else { 2455 // It's OK to do this in the parser, since DU info is always accurate, 2456 // and the parser always refers to nodes via SafePointNode maps. 2457 set_req(MemNode::Memory, mem->in(MemNode::Memory)); 2458 } 2459 return this; 2460 } 2461 } 2462 2463 // Capture an unaliased, unconditional, simple store into an initializer. 2464 // Or, if it is independent of the allocation, hoist it above the allocation. 2465 if (ReduceFieldZeroing && /*can_reshape &&*/ 2466 mem->is_Proj() && mem->in(0)->is_Initialize()) { 2467 InitializeNode* init = mem->in(0)->as_Initialize(); 2468 intptr_t offset = init->can_capture_store(this, phase, can_reshape); 2469 if (offset > 0) { 2470 Node* moved = init->capture_store(this, offset, phase, can_reshape); 2471 // If the InitializeNode captured me, it made a raw copy of me, 2472 // and I need to disappear. 2473 if (moved != NULL) { 2474 // %%% hack to ensure that Ideal returns a new node: 2475 mem = MergeMemNode::make(mem); 2476 return mem; // fold me away 2477 } 2478 } 2479 } 2480 2481 return NULL; // No further progress 2482 } 2483 2484 //------------------------------Value----------------------------------------- 2485 const Type *StoreNode::Value( PhaseTransform *phase ) const { 2486 // Either input is TOP ==> the result is TOP 2487 const Type *t1 = phase->type( in(MemNode::Memory) ); 2488 if( t1 == Type::TOP ) return Type::TOP; 2489 const Type *t2 = phase->type( in(MemNode::Address) ); 2490 if( t2 == Type::TOP ) return Type::TOP; 2491 const Type *t3 = phase->type( in(MemNode::ValueIn) ); 2492 if( t3 == Type::TOP ) return Type::TOP; 2493 return Type::MEMORY; 2494 } 2495 2496 //------------------------------Identity--------------------------------------- 2497 // Remove redundant stores: 2498 // Store(m, p, Load(m, p)) changes to m. 2499 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x). 2500 Node *StoreNode::Identity( PhaseTransform *phase ) { 2501 Node* mem = in(MemNode::Memory); 2502 Node* adr = in(MemNode::Address); 2503 Node* val = in(MemNode::ValueIn); 2504 2505 // Load then Store? Then the Store is useless 2506 if (val->is_Load() && 2507 val->in(MemNode::Address)->eqv_uncast(adr) && 2508 val->in(MemNode::Memory )->eqv_uncast(mem) && 2509 val->as_Load()->store_Opcode() == Opcode()) { 2510 return mem; 2511 } 2512 2513 // Two stores in a row of the same value? 2514 if (mem->is_Store() && 2515 mem->in(MemNode::Address)->eqv_uncast(adr) && 2516 mem->in(MemNode::ValueIn)->eqv_uncast(val) && 2517 mem->Opcode() == Opcode()) { 2518 return mem; 2519 } 2520 2521 // Store of zero anywhere into a freshly-allocated object? 2522 // Then the store is useless. 2523 // (It must already have been captured by the InitializeNode.) 2524 if (ReduceFieldZeroing && phase->type(val)->is_zero_type()) { 2525 // a newly allocated object is already all-zeroes everywhere 2526 if (mem->is_Proj() && mem->in(0)->is_Allocate()) { 2527 return mem; 2528 } 2529 2530 // the store may also apply to zero-bits in an earlier object 2531 Node* prev_mem = find_previous_store(phase); 2532 // Steps (a), (b): Walk past independent stores to find an exact match. 2533 if (prev_mem != NULL) { 2534 Node* prev_val = can_see_stored_value(prev_mem, phase); 2535 if (prev_val != NULL && phase->eqv(prev_val, val)) { 2536 // prev_val and val might differ by a cast; it would be good 2537 // to keep the more informative of the two. 2538 return mem; 2539 } 2540 } 2541 } 2542 2543 return this; 2544 } 2545 2546 //------------------------------match_edge------------------------------------- 2547 // Do we Match on this edge index or not? Match only memory & value 2548 uint StoreNode::match_edge(uint idx) const { 2549 return idx == MemNode::Address || idx == MemNode::ValueIn; 2550 } 2551 2552 //------------------------------cmp-------------------------------------------- 2553 // Do not common stores up together. They generally have to be split 2554 // back up anyways, so do not bother. 2555 uint StoreNode::cmp( const Node &n ) const { 2556 return (&n == this); // Always fail except on self 2557 } 2558 2559 //------------------------------Ideal_masked_input----------------------------- 2560 // Check for a useless mask before a partial-word store 2561 // (StoreB ... (AndI valIn conIa) ) 2562 // If (conIa & mask == mask) this simplifies to 2563 // (StoreB ... (valIn) ) 2564 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) { 2565 Node *val = in(MemNode::ValueIn); 2566 if( val->Opcode() == Op_AndI ) { 2567 const TypeInt *t = phase->type( val->in(2) )->isa_int(); 2568 if( t && t->is_con() && (t->get_con() & mask) == mask ) { 2569 set_req(MemNode::ValueIn, val->in(1)); 2570 return this; 2571 } 2572 } 2573 return NULL; 2574 } 2575 2576 2577 //------------------------------Ideal_sign_extended_input---------------------- 2578 // Check for useless sign-extension before a partial-word store 2579 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) ) 2580 // If (conIL == conIR && conIR <= num_bits) this simplifies to 2581 // (StoreB ... (valIn) ) 2582 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) { 2583 Node *val = in(MemNode::ValueIn); 2584 if( val->Opcode() == Op_RShiftI ) { 2585 const TypeInt *t = phase->type( val->in(2) )->isa_int(); 2586 if( t && t->is_con() && (t->get_con() <= num_bits) ) { 2587 Node *shl = val->in(1); 2588 if( shl->Opcode() == Op_LShiftI ) { 2589 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int(); 2590 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) { 2591 set_req(MemNode::ValueIn, shl->in(1)); 2592 return this; 2593 } 2594 } 2595 } 2596 } 2597 return NULL; 2598 } 2599 2600 //------------------------------value_never_loaded----------------------------------- 2601 // Determine whether there are any possible loads of the value stored. 2602 // For simplicity, we actually check if there are any loads from the 2603 // address stored to, not just for loads of the value stored by this node. 2604 // 2605 bool StoreNode::value_never_loaded( PhaseTransform *phase) const { 2606 Node *adr = in(Address); 2607 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr(); 2608 if (adr_oop == NULL) 2609 return false; 2610 if (!adr_oop->is_known_instance_field()) 2611 return false; // if not a distinct instance, there may be aliases of the address 2612 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) { 2613 Node *use = adr->fast_out(i); 2614 if (use->is_Load() || use->is_LoadStore()) { 2615 return false; 2616 } 2617 } 2618 return true; 2619 } 2620 2621 //============================================================================= 2622 //------------------------------Ideal------------------------------------------ 2623 // If the store is from an AND mask that leaves the low bits untouched, then 2624 // we can skip the AND operation. If the store is from a sign-extension 2625 // (a left shift, then right shift) we can skip both. 2626 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){ 2627 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF); 2628 if( progress != NULL ) return progress; 2629 2630 progress = StoreNode::Ideal_sign_extended_input(phase, 24); 2631 if( progress != NULL ) return progress; 2632 2633 // Finally check the default case 2634 return StoreNode::Ideal(phase, can_reshape); 2635 } 2636 2637 //============================================================================= 2638 //------------------------------Ideal------------------------------------------ 2639 // If the store is from an AND mask that leaves the low bits untouched, then 2640 // we can skip the AND operation 2641 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){ 2642 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF); 2643 if( progress != NULL ) return progress; 2644 2645 progress = StoreNode::Ideal_sign_extended_input(phase, 16); 2646 if( progress != NULL ) return progress; 2647 2648 // Finally check the default case 2649 return StoreNode::Ideal(phase, can_reshape); 2650 } 2651 2652 //============================================================================= 2653 //------------------------------Identity--------------------------------------- 2654 Node *StoreCMNode::Identity( PhaseTransform *phase ) { 2655 // No need to card mark when storing a null ptr 2656 Node* my_store = in(MemNode::OopStore); 2657 if (my_store->is_Store()) { 2658 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) ); 2659 if( t1 == TypePtr::NULL_PTR ) { 2660 return in(MemNode::Memory); 2661 } 2662 } 2663 return this; 2664 } 2665 2666 //============================================================================= 2667 //------------------------------Ideal--------------------------------------- 2668 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){ 2669 Node* progress = StoreNode::Ideal(phase, can_reshape); 2670 if (progress != NULL) return progress; 2671 2672 Node* my_store = in(MemNode::OopStore); 2673 if (my_store->is_MergeMem()) { 2674 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx()); 2675 set_req(MemNode::OopStore, mem); 2676 return this; 2677 } 2678 2679 return NULL; 2680 } 2681 2682 //------------------------------Value----------------------------------------- 2683 const Type *StoreCMNode::Value( PhaseTransform *phase ) const { 2684 // Either input is TOP ==> the result is TOP 2685 const Type *t = phase->type( in(MemNode::Memory) ); 2686 if( t == Type::TOP ) return Type::TOP; 2687 t = phase->type( in(MemNode::Address) ); 2688 if( t == Type::TOP ) return Type::TOP; 2689 t = phase->type( in(MemNode::ValueIn) ); 2690 if( t == Type::TOP ) return Type::TOP; 2691 // If extra input is TOP ==> the result is TOP 2692 t = phase->type( in(MemNode::OopStore) ); 2693 if( t == Type::TOP ) return Type::TOP; 2694 2695 return StoreNode::Value( phase ); 2696 } 2697 2698 2699 //============================================================================= 2700 //----------------------------------SCMemProjNode------------------------------ 2701 const Type * SCMemProjNode::Value( PhaseTransform *phase ) const 2702 { 2703 return bottom_type(); 2704 } 2705 2706 //============================================================================= 2707 //----------------------------------LoadStoreNode------------------------------ 2708 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required ) 2709 : Node(required), 2710 _type(rt), 2711 _adr_type(at) 2712 { 2713 init_req(MemNode::Control, c ); 2714 init_req(MemNode::Memory , mem); 2715 init_req(MemNode::Address, adr); 2716 init_req(MemNode::ValueIn, val); 2717 init_class_id(Class_LoadStore); 2718 } 2719 2720 uint LoadStoreNode::ideal_reg() const { 2721 return _type->ideal_reg(); 2722 } 2723 2724 bool LoadStoreNode::result_not_used() const { 2725 for( DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++ ) { 2726 Node *x = fast_out(i); 2727 if (x->Opcode() == Op_SCMemProj) continue; 2728 return false; 2729 } 2730 return true; 2731 } 2732 2733 uint LoadStoreNode::size_of() const { return sizeof(*this); } 2734 2735 //============================================================================= 2736 //----------------------------------LoadStoreConditionalNode-------------------- 2737 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, NULL, TypeInt::BOOL, 5) { 2738 init_req(ExpectedIn, ex ); 2739 } 2740 2741 //============================================================================= 2742 //-------------------------------adr_type-------------------------------------- 2743 const TypePtr* ClearArrayNode::adr_type() const { 2744 Node *adr = in(3); 2745 if (adr == NULL) return NULL; // node is dead 2746 return MemNode::calculate_adr_type(adr->bottom_type()); 2747 } 2748 2749 //------------------------------match_edge------------------------------------- 2750 // Do we Match on this edge index or not? Do not match memory 2751 uint ClearArrayNode::match_edge(uint idx) const { 2752 return idx > 1; 2753 } 2754 2755 //------------------------------Identity--------------------------------------- 2756 // Clearing a zero length array does nothing 2757 Node *ClearArrayNode::Identity( PhaseTransform *phase ) { 2758 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this; 2759 } 2760 2761 //------------------------------Idealize--------------------------------------- 2762 // Clearing a short array is faster with stores 2763 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape){ 2764 const int unit = BytesPerLong; 2765 const TypeX* t = phase->type(in(2))->isa_intptr_t(); 2766 if (!t) return NULL; 2767 if (!t->is_con()) return NULL; 2768 intptr_t raw_count = t->get_con(); 2769 intptr_t size = raw_count; 2770 if (!Matcher::init_array_count_is_in_bytes) size *= unit; 2771 // Clearing nothing uses the Identity call. 2772 // Negative clears are possible on dead ClearArrays 2773 // (see jck test stmt114.stmt11402.val). 2774 if (size <= 0 || size % unit != 0) return NULL; 2775 intptr_t count = size / unit; 2776 // Length too long; use fast hardware clear 2777 if (size > Matcher::init_array_short_size) return NULL; 2778 Node *mem = in(1); 2779 if( phase->type(mem)==Type::TOP ) return NULL; 2780 Node *adr = in(3); 2781 const Type* at = phase->type(adr); 2782 if( at==Type::TOP ) return NULL; 2783 const TypePtr* atp = at->isa_ptr(); 2784 // adjust atp to be the correct array element address type 2785 if (atp == NULL) atp = TypePtr::BOTTOM; 2786 else atp = atp->add_offset(Type::OffsetBot); 2787 // Get base for derived pointer purposes 2788 if( adr->Opcode() != Op_AddP ) Unimplemented(); 2789 Node *base = adr->in(1); 2790 2791 Node *zero = phase->makecon(TypeLong::ZERO); 2792 Node *off = phase->MakeConX(BytesPerLong); 2793 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false); 2794 count--; 2795 while( count-- ) { 2796 mem = phase->transform(mem); 2797 adr = phase->transform(new AddPNode(base,adr,off)); 2798 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false); 2799 } 2800 return mem; 2801 } 2802 2803 //----------------------------step_through---------------------------------- 2804 // Return allocation input memory edge if it is different instance 2805 // or itself if it is the one we are looking for. 2806 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) { 2807 Node* n = *np; 2808 assert(n->is_ClearArray(), "sanity"); 2809 intptr_t offset; 2810 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset); 2811 // This method is called only before Allocate nodes are expanded 2812 // during macro nodes expansion. Before that ClearArray nodes are 2813 // only generated in PhaseMacroExpand::generate_arraycopy() (before 2814 // Allocate nodes are expanded) which follows allocations. 2815 assert(alloc != NULL, "should have allocation"); 2816 if (alloc->_idx == instance_id) { 2817 // Can not bypass initialization of the instance we are looking for. 2818 return false; 2819 } 2820 // Otherwise skip it. 2821 InitializeNode* init = alloc->initialization(); 2822 if (init != NULL) 2823 *np = init->in(TypeFunc::Memory); 2824 else 2825 *np = alloc->in(TypeFunc::Memory); 2826 return true; 2827 } 2828 2829 //----------------------------clear_memory------------------------------------- 2830 // Generate code to initialize object storage to zero. 2831 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest, 2832 intptr_t start_offset, 2833 Node* end_offset, 2834 PhaseGVN* phase) { 2835 intptr_t offset = start_offset; 2836 2837 int unit = BytesPerLong; 2838 if ((offset % unit) != 0) { 2839 Node* adr = new AddPNode(dest, dest, phase->MakeConX(offset)); 2840 adr = phase->transform(adr); 2841 const TypePtr* atp = TypeRawPtr::BOTTOM; 2842 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered); 2843 mem = phase->transform(mem); 2844 offset += BytesPerInt; 2845 } 2846 assert((offset % unit) == 0, ""); 2847 2848 // Initialize the remaining stuff, if any, with a ClearArray. 2849 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase); 2850 } 2851 2852 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest, 2853 Node* start_offset, 2854 Node* end_offset, 2855 PhaseGVN* phase) { 2856 if (start_offset == end_offset) { 2857 // nothing to do 2858 return mem; 2859 } 2860 2861 int unit = BytesPerLong; 2862 Node* zbase = start_offset; 2863 Node* zend = end_offset; 2864 2865 // Scale to the unit required by the CPU: 2866 if (!Matcher::init_array_count_is_in_bytes) { 2867 Node* shift = phase->intcon(exact_log2(unit)); 2868 zbase = phase->transform(new URShiftXNode(zbase, shift) ); 2869 zend = phase->transform(new URShiftXNode(zend, shift) ); 2870 } 2871 2872 // Bulk clear double-words 2873 Node* zsize = phase->transform(new SubXNode(zend, zbase) ); 2874 Node* adr = phase->transform(new AddPNode(dest, dest, start_offset) ); 2875 mem = new ClearArrayNode(ctl, mem, zsize, adr); 2876 return phase->transform(mem); 2877 } 2878 2879 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest, 2880 intptr_t start_offset, 2881 intptr_t end_offset, 2882 PhaseGVN* phase) { 2883 if (start_offset == end_offset) { 2884 // nothing to do 2885 return mem; 2886 } 2887 2888 assert((end_offset % BytesPerInt) == 0, "odd end offset"); 2889 intptr_t done_offset = end_offset; 2890 if ((done_offset % BytesPerLong) != 0) { 2891 done_offset -= BytesPerInt; 2892 } 2893 if (done_offset > start_offset) { 2894 mem = clear_memory(ctl, mem, dest, 2895 start_offset, phase->MakeConX(done_offset), phase); 2896 } 2897 if (done_offset < end_offset) { // emit the final 32-bit store 2898 Node* adr = new AddPNode(dest, dest, phase->MakeConX(done_offset)); 2899 adr = phase->transform(adr); 2900 const TypePtr* atp = TypeRawPtr::BOTTOM; 2901 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered); 2902 mem = phase->transform(mem); 2903 done_offset += BytesPerInt; 2904 } 2905 assert(done_offset == end_offset, ""); 2906 return mem; 2907 } 2908 2909 //============================================================================= 2910 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent) 2911 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)), 2912 _adr_type(C->get_adr_type(alias_idx)) 2913 { 2914 init_class_id(Class_MemBar); 2915 Node* top = C->top(); 2916 init_req(TypeFunc::I_O,top); 2917 init_req(TypeFunc::FramePtr,top); 2918 init_req(TypeFunc::ReturnAdr,top); 2919 if (precedent != NULL) 2920 init_req(TypeFunc::Parms, precedent); 2921 } 2922 2923 //------------------------------cmp-------------------------------------------- 2924 uint MemBarNode::hash() const { return NO_HASH; } 2925 uint MemBarNode::cmp( const Node &n ) const { 2926 return (&n == this); // Always fail except on self 2927 } 2928 2929 //------------------------------make------------------------------------------- 2930 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) { 2931 switch (opcode) { 2932 case Op_MemBarAcquire: return new MemBarAcquireNode(C, atp, pn); 2933 case Op_LoadFence: return new LoadFenceNode(C, atp, pn); 2934 case Op_MemBarRelease: return new MemBarReleaseNode(C, atp, pn); 2935 case Op_StoreFence: return new StoreFenceNode(C, atp, pn); 2936 case Op_MemBarAcquireLock: return new MemBarAcquireLockNode(C, atp, pn); 2937 case Op_MemBarReleaseLock: return new MemBarReleaseLockNode(C, atp, pn); 2938 case Op_MemBarVolatile: return new MemBarVolatileNode(C, atp, pn); 2939 case Op_MemBarCPUOrder: return new MemBarCPUOrderNode(C, atp, pn); 2940 case Op_Initialize: return new InitializeNode(C, atp, pn); 2941 case Op_MemBarStoreStore: return new MemBarStoreStoreNode(C, atp, pn); 2942 default: ShouldNotReachHere(); return NULL; 2943 } 2944 } 2945 2946 //------------------------------Ideal------------------------------------------ 2947 // Return a node which is more "ideal" than the current node. Strip out 2948 // control copies 2949 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2950 if (remove_dead_region(phase, can_reshape)) return this; 2951 // Don't bother trying to transform a dead node 2952 if (in(0) && in(0)->is_top()) { 2953 return NULL; 2954 } 2955 2956 bool progress = false; 2957 // Eliminate volatile MemBars for scalar replaced objects. 2958 if (can_reshape && req() == (Precedent+1)) { 2959 bool eliminate = false; 2960 int opc = Opcode(); 2961 if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) { 2962 // Volatile field loads and stores. 2963 Node* my_mem = in(MemBarNode::Precedent); 2964 // The MembarAquire may keep an unused LoadNode alive through the Precedent edge 2965 if ((my_mem != NULL) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) { 2966 // if the Precedent is a decodeN and its input (a Load) is used at more than one place, 2967 // replace this Precedent (decodeN) with the Load instead. 2968 if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1)) { 2969 Node* load_node = my_mem->in(1); 2970 set_req(MemBarNode::Precedent, load_node); 2971 phase->is_IterGVN()->_worklist.push(my_mem); 2972 my_mem = load_node; 2973 } else { 2974 assert(my_mem->unique_out() == this, "sanity"); 2975 del_req(Precedent); 2976 phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later 2977 my_mem = NULL; 2978 } 2979 progress = true; 2980 } 2981 if (my_mem != NULL && my_mem->is_Mem()) { 2982 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr(); 2983 // Check for scalar replaced object reference. 2984 if( t_oop != NULL && t_oop->is_known_instance_field() && 2985 t_oop->offset() != Type::OffsetBot && 2986 t_oop->offset() != Type::OffsetTop) { 2987 eliminate = true; 2988 } 2989 } 2990 } else if (opc == Op_MemBarRelease) { 2991 // Final field stores. 2992 Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent), phase); 2993 if ((alloc != NULL) && alloc->is_Allocate() && 2994 alloc->as_Allocate()->_is_non_escaping) { 2995 // The allocated object does not escape. 2996 eliminate = true; 2997 } 2998 } 2999 if (eliminate) { 3000 // Replace MemBar projections by its inputs. 3001 PhaseIterGVN* igvn = phase->is_IterGVN(); 3002 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory)); 3003 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control)); 3004 // Must return either the original node (now dead) or a new node 3005 // (Do not return a top here, since that would break the uniqueness of top.) 3006 return new ConINode(TypeInt::ZERO); 3007 } 3008 } 3009 return progress ? this : NULL; 3010 } 3011 3012 //------------------------------Value------------------------------------------ 3013 const Type *MemBarNode::Value( PhaseTransform *phase ) const { 3014 if( !in(0) ) return Type::TOP; 3015 if( phase->type(in(0)) == Type::TOP ) 3016 return Type::TOP; 3017 return TypeTuple::MEMBAR; 3018 } 3019 3020 //------------------------------match------------------------------------------ 3021 // Construct projections for memory. 3022 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) { 3023 switch (proj->_con) { 3024 case TypeFunc::Control: 3025 case TypeFunc::Memory: 3026 return new MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj); 3027 } 3028 ShouldNotReachHere(); 3029 return NULL; 3030 } 3031 3032 //===========================InitializeNode==================================== 3033 // SUMMARY: 3034 // This node acts as a memory barrier on raw memory, after some raw stores. 3035 // The 'cooked' oop value feeds from the Initialize, not the Allocation. 3036 // The Initialize can 'capture' suitably constrained stores as raw inits. 3037 // It can coalesce related raw stores into larger units (called 'tiles'). 3038 // It can avoid zeroing new storage for memory units which have raw inits. 3039 // At macro-expansion, it is marked 'complete', and does not optimize further. 3040 // 3041 // EXAMPLE: 3042 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine. 3043 // ctl = incoming control; mem* = incoming memory 3044 // (Note: A star * on a memory edge denotes I/O and other standard edges.) 3045 // First allocate uninitialized memory and fill in the header: 3046 // alloc = (Allocate ctl mem* 16 #short[].klass ...) 3047 // ctl := alloc.Control; mem* := alloc.Memory* 3048 // rawmem = alloc.Memory; rawoop = alloc.RawAddress 3049 // Then initialize to zero the non-header parts of the raw memory block: 3050 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress) 3051 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory 3052 // After the initialize node executes, the object is ready for service: 3053 // oop := (CheckCastPP init.Control alloc.RawAddress #short[]) 3054 // Suppose its body is immediately initialized as {1,2}: 3055 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1) 3056 // store2 = (StoreC init.Control store1 (+ oop 14) 2) 3057 // mem.SLICE(#short[*]) := store2 3058 // 3059 // DETAILS: 3060 // An InitializeNode collects and isolates object initialization after 3061 // an AllocateNode and before the next possible safepoint. As a 3062 // memory barrier (MemBarNode), it keeps critical stores from drifting 3063 // down past any safepoint or any publication of the allocation. 3064 // Before this barrier, a newly-allocated object may have uninitialized bits. 3065 // After this barrier, it may be treated as a real oop, and GC is allowed. 3066 // 3067 // The semantics of the InitializeNode include an implicit zeroing of 3068 // the new object from object header to the end of the object. 3069 // (The object header and end are determined by the AllocateNode.) 3070 // 3071 // Certain stores may be added as direct inputs to the InitializeNode. 3072 // These stores must update raw memory, and they must be to addresses 3073 // derived from the raw address produced by AllocateNode, and with 3074 // a constant offset. They must be ordered by increasing offset. 3075 // The first one is at in(RawStores), the last at in(req()-1). 3076 // Unlike most memory operations, they are not linked in a chain, 3077 // but are displayed in parallel as users of the rawmem output of 3078 // the allocation. 3079 // 3080 // (See comments in InitializeNode::capture_store, which continue 3081 // the example given above.) 3082 // 3083 // When the associated Allocate is macro-expanded, the InitializeNode 3084 // may be rewritten to optimize collected stores. A ClearArrayNode 3085 // may also be created at that point to represent any required zeroing. 3086 // The InitializeNode is then marked 'complete', prohibiting further 3087 // capturing of nearby memory operations. 3088 // 3089 // During macro-expansion, all captured initializations which store 3090 // constant values of 32 bits or smaller are coalesced (if advantageous) 3091 // into larger 'tiles' 32 or 64 bits. This allows an object to be 3092 // initialized in fewer memory operations. Memory words which are 3093 // covered by neither tiles nor non-constant stores are pre-zeroed 3094 // by explicit stores of zero. (The code shape happens to do all 3095 // zeroing first, then all other stores, with both sequences occurring 3096 // in order of ascending offsets.) 3097 // 3098 // Alternatively, code may be inserted between an AllocateNode and its 3099 // InitializeNode, to perform arbitrary initialization of the new object. 3100 // E.g., the object copying intrinsics insert complex data transfers here. 3101 // The initialization must then be marked as 'complete' disable the 3102 // built-in zeroing semantics and the collection of initializing stores. 3103 // 3104 // While an InitializeNode is incomplete, reads from the memory state 3105 // produced by it are optimizable if they match the control edge and 3106 // new oop address associated with the allocation/initialization. 3107 // They return a stored value (if the offset matches) or else zero. 3108 // A write to the memory state, if it matches control and address, 3109 // and if it is to a constant offset, may be 'captured' by the 3110 // InitializeNode. It is cloned as a raw memory operation and rewired 3111 // inside the initialization, to the raw oop produced by the allocation. 3112 // Operations on addresses which are provably distinct (e.g., to 3113 // other AllocateNodes) are allowed to bypass the initialization. 3114 // 3115 // The effect of all this is to consolidate object initialization 3116 // (both arrays and non-arrays, both piecewise and bulk) into a 3117 // single location, where it can be optimized as a unit. 3118 // 3119 // Only stores with an offset less than TrackedInitializationLimit words 3120 // will be considered for capture by an InitializeNode. This puts a 3121 // reasonable limit on the complexity of optimized initializations. 3122 3123 //---------------------------InitializeNode------------------------------------ 3124 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop) 3125 : _is_complete(Incomplete), _does_not_escape(false), 3126 MemBarNode(C, adr_type, rawoop) 3127 { 3128 init_class_id(Class_Initialize); 3129 3130 assert(adr_type == Compile::AliasIdxRaw, "only valid atp"); 3131 assert(in(RawAddress) == rawoop, "proper init"); 3132 // Note: allocation() can be NULL, for secondary initialization barriers 3133 } 3134 3135 // Since this node is not matched, it will be processed by the 3136 // register allocator. Declare that there are no constraints 3137 // on the allocation of the RawAddress edge. 3138 const RegMask &InitializeNode::in_RegMask(uint idx) const { 3139 // This edge should be set to top, by the set_complete. But be conservative. 3140 if (idx == InitializeNode::RawAddress) 3141 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]); 3142 return RegMask::Empty; 3143 } 3144 3145 Node* InitializeNode::memory(uint alias_idx) { 3146 Node* mem = in(Memory); 3147 if (mem->is_MergeMem()) { 3148 return mem->as_MergeMem()->memory_at(alias_idx); 3149 } else { 3150 // incoming raw memory is not split 3151 return mem; 3152 } 3153 } 3154 3155 bool InitializeNode::is_non_zero() { 3156 if (is_complete()) return false; 3157 remove_extra_zeroes(); 3158 return (req() > RawStores); 3159 } 3160 3161 void InitializeNode::set_complete(PhaseGVN* phase) { 3162 assert(!is_complete(), "caller responsibility"); 3163 _is_complete = Complete; 3164 3165 // After this node is complete, it contains a bunch of 3166 // raw-memory initializations. There is no need for 3167 // it to have anything to do with non-raw memory effects. 3168 // Therefore, tell all non-raw users to re-optimize themselves, 3169 // after skipping the memory effects of this initialization. 3170 PhaseIterGVN* igvn = phase->is_IterGVN(); 3171 if (igvn) igvn->add_users_to_worklist(this); 3172 } 3173 3174 // convenience function 3175 // return false if the init contains any stores already 3176 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) { 3177 InitializeNode* init = initialization(); 3178 if (init == NULL || init->is_complete()) return false; 3179 init->remove_extra_zeroes(); 3180 // for now, if this allocation has already collected any inits, bail: 3181 if (init->is_non_zero()) return false; 3182 init->set_complete(phase); 3183 return true; 3184 } 3185 3186 void InitializeNode::remove_extra_zeroes() { 3187 if (req() == RawStores) return; 3188 Node* zmem = zero_memory(); 3189 uint fill = RawStores; 3190 for (uint i = fill; i < req(); i++) { 3191 Node* n = in(i); 3192 if (n->is_top() || n == zmem) continue; // skip 3193 if (fill < i) set_req(fill, n); // compact 3194 ++fill; 3195 } 3196 // delete any empty spaces created: 3197 while (fill < req()) { 3198 del_req(fill); 3199 } 3200 } 3201 3202 // Helper for remembering which stores go with which offsets. 3203 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) { 3204 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node 3205 intptr_t offset = -1; 3206 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address), 3207 phase, offset); 3208 if (base == NULL) return -1; // something is dead, 3209 if (offset < 0) return -1; // dead, dead 3210 return offset; 3211 } 3212 3213 // Helper for proving that an initialization expression is 3214 // "simple enough" to be folded into an object initialization. 3215 // Attempts to prove that a store's initial value 'n' can be captured 3216 // within the initialization without creating a vicious cycle, such as: 3217 // { Foo p = new Foo(); p.next = p; } 3218 // True for constants and parameters and small combinations thereof. 3219 bool InitializeNode::detect_init_independence(Node* n, int& count) { 3220 if (n == NULL) return true; // (can this really happen?) 3221 if (n->is_Proj()) n = n->in(0); 3222 if (n == this) return false; // found a cycle 3223 if (n->is_Con()) return true; 3224 if (n->is_Start()) return true; // params, etc., are OK 3225 if (n->is_Root()) return true; // even better 3226 3227 Node* ctl = n->in(0); 3228 if (ctl != NULL && !ctl->is_top()) { 3229 if (ctl->is_Proj()) ctl = ctl->in(0); 3230 if (ctl == this) return false; 3231 3232 // If we already know that the enclosing memory op is pinned right after 3233 // the init, then any control flow that the store has picked up 3234 // must have preceded the init, or else be equal to the init. 3235 // Even after loop optimizations (which might change control edges) 3236 // a store is never pinned *before* the availability of its inputs. 3237 if (!MemNode::all_controls_dominate(n, this)) 3238 return false; // failed to prove a good control 3239 } 3240 3241 // Check data edges for possible dependencies on 'this'. 3242 if ((count += 1) > 20) return false; // complexity limit 3243 for (uint i = 1; i < n->req(); i++) { 3244 Node* m = n->in(i); 3245 if (m == NULL || m == n || m->is_top()) continue; 3246 uint first_i = n->find_edge(m); 3247 if (i != first_i) continue; // process duplicate edge just once 3248 if (!detect_init_independence(m, count)) { 3249 return false; 3250 } 3251 } 3252 3253 return true; 3254 } 3255 3256 // Here are all the checks a Store must pass before it can be moved into 3257 // an initialization. Returns zero if a check fails. 3258 // On success, returns the (constant) offset to which the store applies, 3259 // within the initialized memory. 3260 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase, bool can_reshape) { 3261 const int FAIL = 0; 3262 if (st->req() != MemNode::ValueIn + 1) 3263 return FAIL; // an inscrutable StoreNode (card mark?) 3264 Node* ctl = st->in(MemNode::Control); 3265 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this)) 3266 return FAIL; // must be unconditional after the initialization 3267 Node* mem = st->in(MemNode::Memory); 3268 if (!(mem->is_Proj() && mem->in(0) == this)) 3269 return FAIL; // must not be preceded by other stores 3270 Node* adr = st->in(MemNode::Address); 3271 intptr_t offset; 3272 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset); 3273 if (alloc == NULL) 3274 return FAIL; // inscrutable address 3275 if (alloc != allocation()) 3276 return FAIL; // wrong allocation! (store needs to float up) 3277 Node* val = st->in(MemNode::ValueIn); 3278 int complexity_count = 0; 3279 if (!detect_init_independence(val, complexity_count)) 3280 return FAIL; // stored value must be 'simple enough' 3281 3282 // The Store can be captured only if nothing after the allocation 3283 // and before the Store is using the memory location that the store 3284 // overwrites. 3285 bool failed = false; 3286 // If is_complete_with_arraycopy() is true the shape of the graph is 3287 // well defined and is safe so no need for extra checks. 3288 if (!is_complete_with_arraycopy()) { 3289 // We are going to look at each use of the memory state following 3290 // the allocation to make sure nothing reads the memory that the 3291 // Store writes. 3292 const TypePtr* t_adr = phase->type(adr)->isa_ptr(); 3293 int alias_idx = phase->C->get_alias_index(t_adr); 3294 ResourceMark rm; 3295 Unique_Node_List mems; 3296 mems.push(mem); 3297 Node* unique_merge = NULL; 3298 for (uint next = 0; next < mems.size(); ++next) { 3299 Node *m = mems.at(next); 3300 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) { 3301 Node *n = m->fast_out(j); 3302 if (n->outcnt() == 0) { 3303 continue; 3304 } 3305 if (n == st) { 3306 continue; 3307 } else if (n->in(0) != NULL && n->in(0) != ctl) { 3308 // If the control of this use is different from the control 3309 // of the Store which is right after the InitializeNode then 3310 // this node cannot be between the InitializeNode and the 3311 // Store. 3312 continue; 3313 } else if (n->is_MergeMem()) { 3314 if (n->as_MergeMem()->memory_at(alias_idx) == m) { 3315 // We can hit a MergeMemNode (that will likely go away 3316 // later) that is a direct use of the memory state 3317 // following the InitializeNode on the same slice as the 3318 // store node that we'd like to capture. We need to check 3319 // the uses of the MergeMemNode. 3320 mems.push(n); 3321 } 3322 } else if (n->is_Mem()) { 3323 Node* other_adr = n->in(MemNode::Address); 3324 if (other_adr == adr) { 3325 failed = true; 3326 break; 3327 } else { 3328 const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr(); 3329 if (other_t_adr != NULL) { 3330 int other_alias_idx = phase->C->get_alias_index(other_t_adr); 3331 if (other_alias_idx == alias_idx) { 3332 // A load from the same memory slice as the store right 3333 // after the InitializeNode. We check the control of the 3334 // object/array that is loaded from. If it's the same as 3335 // the store control then we cannot capture the store. 3336 assert(!n->is_Store(), "2 stores to same slice on same control?"); 3337 Node* base = other_adr; 3338 assert(base->is_AddP(), err_msg_res("should be addp but is %s", base->Name())); 3339 base = base->in(AddPNode::Base); 3340 if (base != NULL) { 3341 base = base->uncast(); 3342 if (base->is_Proj() && base->in(0) == alloc) { 3343 failed = true; 3344 break; 3345 } 3346 } 3347 } 3348 } 3349 } 3350 } else { 3351 failed = true; 3352 break; 3353 } 3354 } 3355 } 3356 } 3357 if (failed) { 3358 if (!can_reshape) { 3359 // We decided we couldn't capture the store during parsing. We 3360 // should try again during the next IGVN once the graph is 3361 // cleaner. 3362 phase->C->record_for_igvn(st); 3363 } 3364 return FAIL; 3365 } 3366 3367 return offset; // success 3368 } 3369 3370 // Find the captured store in(i) which corresponds to the range 3371 // [start..start+size) in the initialized object. 3372 // If there is one, return its index i. If there isn't, return the 3373 // negative of the index where it should be inserted. 3374 // Return 0 if the queried range overlaps an initialization boundary 3375 // or if dead code is encountered. 3376 // If size_in_bytes is zero, do not bother with overlap checks. 3377 int InitializeNode::captured_store_insertion_point(intptr_t start, 3378 int size_in_bytes, 3379 PhaseTransform* phase) { 3380 const int FAIL = 0, MAX_STORE = BytesPerLong; 3381 3382 if (is_complete()) 3383 return FAIL; // arraycopy got here first; punt 3384 3385 assert(allocation() != NULL, "must be present"); 3386 3387 // no negatives, no header fields: 3388 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL; 3389 3390 // after a certain size, we bail out on tracking all the stores: 3391 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize); 3392 if (start >= ti_limit) return FAIL; 3393 3394 for (uint i = InitializeNode::RawStores, limit = req(); ; ) { 3395 if (i >= limit) return -(int)i; // not found; here is where to put it 3396 3397 Node* st = in(i); 3398 intptr_t st_off = get_store_offset(st, phase); 3399 if (st_off < 0) { 3400 if (st != zero_memory()) { 3401 return FAIL; // bail out if there is dead garbage 3402 } 3403 } else if (st_off > start) { 3404 // ...we are done, since stores are ordered 3405 if (st_off < start + size_in_bytes) { 3406 return FAIL; // the next store overlaps 3407 } 3408 return -(int)i; // not found; here is where to put it 3409 } else if (st_off < start) { 3410 if (size_in_bytes != 0 && 3411 start < st_off + MAX_STORE && 3412 start < st_off + st->as_Store()->memory_size()) { 3413 return FAIL; // the previous store overlaps 3414 } 3415 } else { 3416 if (size_in_bytes != 0 && 3417 st->as_Store()->memory_size() != size_in_bytes) { 3418 return FAIL; // mismatched store size 3419 } 3420 return i; 3421 } 3422 3423 ++i; 3424 } 3425 } 3426 3427 // Look for a captured store which initializes at the offset 'start' 3428 // with the given size. If there is no such store, and no other 3429 // initialization interferes, then return zero_memory (the memory 3430 // projection of the AllocateNode). 3431 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes, 3432 PhaseTransform* phase) { 3433 assert(stores_are_sane(phase), ""); 3434 int i = captured_store_insertion_point(start, size_in_bytes, phase); 3435 if (i == 0) { 3436 return NULL; // something is dead 3437 } else if (i < 0) { 3438 return zero_memory(); // just primordial zero bits here 3439 } else { 3440 Node* st = in(i); // here is the store at this position 3441 assert(get_store_offset(st->as_Store(), phase) == start, "sanity"); 3442 return st; 3443 } 3444 } 3445 3446 // Create, as a raw pointer, an address within my new object at 'offset'. 3447 Node* InitializeNode::make_raw_address(intptr_t offset, 3448 PhaseTransform* phase) { 3449 Node* addr = in(RawAddress); 3450 if (offset != 0) { 3451 Compile* C = phase->C; 3452 addr = phase->transform( new AddPNode(C->top(), addr, 3453 phase->MakeConX(offset)) ); 3454 } 3455 return addr; 3456 } 3457 3458 // Clone the given store, converting it into a raw store 3459 // initializing a field or element of my new object. 3460 // Caller is responsible for retiring the original store, 3461 // with subsume_node or the like. 3462 // 3463 // From the example above InitializeNode::InitializeNode, 3464 // here are the old stores to be captured: 3465 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1) 3466 // store2 = (StoreC init.Control store1 (+ oop 14) 2) 3467 // 3468 // Here is the changed code; note the extra edges on init: 3469 // alloc = (Allocate ...) 3470 // rawoop = alloc.RawAddress 3471 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1) 3472 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2) 3473 // init = (Initialize alloc.Control alloc.Memory rawoop 3474 // rawstore1 rawstore2) 3475 // 3476 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start, 3477 PhaseTransform* phase, bool can_reshape) { 3478 assert(stores_are_sane(phase), ""); 3479 3480 if (start < 0) return NULL; 3481 assert(can_capture_store(st, phase, can_reshape) == start, "sanity"); 3482 3483 Compile* C = phase->C; 3484 int size_in_bytes = st->memory_size(); 3485 int i = captured_store_insertion_point(start, size_in_bytes, phase); 3486 if (i == 0) return NULL; // bail out 3487 Node* prev_mem = NULL; // raw memory for the captured store 3488 if (i > 0) { 3489 prev_mem = in(i); // there is a pre-existing store under this one 3490 set_req(i, C->top()); // temporarily disconnect it 3491 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect. 3492 } else { 3493 i = -i; // no pre-existing store 3494 prev_mem = zero_memory(); // a slice of the newly allocated object 3495 if (i > InitializeNode::RawStores && in(i-1) == prev_mem) 3496 set_req(--i, C->top()); // reuse this edge; it has been folded away 3497 else 3498 ins_req(i, C->top()); // build a new edge 3499 } 3500 Node* new_st = st->clone(); 3501 new_st->set_req(MemNode::Control, in(Control)); 3502 new_st->set_req(MemNode::Memory, prev_mem); 3503 new_st->set_req(MemNode::Address, make_raw_address(start, phase)); 3504 new_st = phase->transform(new_st); 3505 3506 // At this point, new_st might have swallowed a pre-existing store 3507 // at the same offset, or perhaps new_st might have disappeared, 3508 // if it redundantly stored the same value (or zero to fresh memory). 3509 3510 // In any case, wire it in: 3511 phase->igvn_rehash_node_delayed(this); 3512 set_req(i, new_st); 3513 3514 // The caller may now kill the old guy. 3515 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase)); 3516 assert(check_st == new_st || check_st == NULL, "must be findable"); 3517 assert(!is_complete(), ""); 3518 return new_st; 3519 } 3520 3521 static bool store_constant(jlong* tiles, int num_tiles, 3522 intptr_t st_off, int st_size, 3523 jlong con) { 3524 if ((st_off & (st_size-1)) != 0) 3525 return false; // strange store offset (assume size==2**N) 3526 address addr = (address)tiles + st_off; 3527 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob"); 3528 switch (st_size) { 3529 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break; 3530 case sizeof(jchar): *(jchar*) addr = (jchar) con; break; 3531 case sizeof(jint): *(jint*) addr = (jint) con; break; 3532 case sizeof(jlong): *(jlong*) addr = (jlong) con; break; 3533 default: return false; // strange store size (detect size!=2**N here) 3534 } 3535 return true; // return success to caller 3536 } 3537 3538 // Coalesce subword constants into int constants and possibly 3539 // into long constants. The goal, if the CPU permits, 3540 // is to initialize the object with a small number of 64-bit tiles. 3541 // Also, convert floating-point constants to bit patterns. 3542 // Non-constants are not relevant to this pass. 3543 // 3544 // In terms of the running example on InitializeNode::InitializeNode 3545 // and InitializeNode::capture_store, here is the transformation 3546 // of rawstore1 and rawstore2 into rawstore12: 3547 // alloc = (Allocate ...) 3548 // rawoop = alloc.RawAddress 3549 // tile12 = 0x00010002 3550 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12) 3551 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12) 3552 // 3553 void 3554 InitializeNode::coalesce_subword_stores(intptr_t header_size, 3555 Node* size_in_bytes, 3556 PhaseGVN* phase) { 3557 Compile* C = phase->C; 3558 3559 assert(stores_are_sane(phase), ""); 3560 // Note: After this pass, they are not completely sane, 3561 // since there may be some overlaps. 3562 3563 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0; 3564 3565 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize); 3566 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit); 3567 size_limit = MIN2(size_limit, ti_limit); 3568 size_limit = align_size_up(size_limit, BytesPerLong); 3569 int num_tiles = size_limit / BytesPerLong; 3570 3571 // allocate space for the tile map: 3572 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small 3573 jlong tiles_buf[small_len]; 3574 Node* nodes_buf[small_len]; 3575 jlong inits_buf[small_len]; 3576 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0] 3577 : NEW_RESOURCE_ARRAY(jlong, num_tiles)); 3578 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0] 3579 : NEW_RESOURCE_ARRAY(Node*, num_tiles)); 3580 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0] 3581 : NEW_RESOURCE_ARRAY(jlong, num_tiles)); 3582 // tiles: exact bitwise model of all primitive constants 3583 // nodes: last constant-storing node subsumed into the tiles model 3584 // inits: which bytes (in each tile) are touched by any initializations 3585 3586 //// Pass A: Fill in the tile model with any relevant stores. 3587 3588 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles); 3589 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles); 3590 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles); 3591 Node* zmem = zero_memory(); // initially zero memory state 3592 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) { 3593 Node* st = in(i); 3594 intptr_t st_off = get_store_offset(st, phase); 3595 3596 // Figure out the store's offset and constant value: 3597 if (st_off < header_size) continue; //skip (ignore header) 3598 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain) 3599 int st_size = st->as_Store()->memory_size(); 3600 if (st_off + st_size > size_limit) break; 3601 3602 // Record which bytes are touched, whether by constant or not. 3603 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1)) 3604 continue; // skip (strange store size) 3605 3606 const Type* val = phase->type(st->in(MemNode::ValueIn)); 3607 if (!val->singleton()) continue; //skip (non-con store) 3608 BasicType type = val->basic_type(); 3609 3610 jlong con = 0; 3611 switch (type) { 3612 case T_INT: con = val->is_int()->get_con(); break; 3613 case T_LONG: con = val->is_long()->get_con(); break; 3614 case T_FLOAT: con = jint_cast(val->getf()); break; 3615 case T_DOUBLE: con = jlong_cast(val->getd()); break; 3616 default: continue; //skip (odd store type) 3617 } 3618 3619 if (type == T_LONG && Matcher::isSimpleConstant64(con) && 3620 st->Opcode() == Op_StoreL) { 3621 continue; // This StoreL is already optimal. 3622 } 3623 3624 // Store down the constant. 3625 store_constant(tiles, num_tiles, st_off, st_size, con); 3626 3627 intptr_t j = st_off >> LogBytesPerLong; 3628 3629 if (type == T_INT && st_size == BytesPerInt 3630 && (st_off & BytesPerInt) == BytesPerInt) { 3631 jlong lcon = tiles[j]; 3632 if (!Matcher::isSimpleConstant64(lcon) && 3633 st->Opcode() == Op_StoreI) { 3634 // This StoreI is already optimal by itself. 3635 jint* intcon = (jint*) &tiles[j]; 3636 intcon[1] = 0; // undo the store_constant() 3637 3638 // If the previous store is also optimal by itself, back up and 3639 // undo the action of the previous loop iteration... if we can. 3640 // But if we can't, just let the previous half take care of itself. 3641 st = nodes[j]; 3642 st_off -= BytesPerInt; 3643 con = intcon[0]; 3644 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) { 3645 assert(st_off >= header_size, "still ignoring header"); 3646 assert(get_store_offset(st, phase) == st_off, "must be"); 3647 assert(in(i-1) == zmem, "must be"); 3648 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn))); 3649 assert(con == tcon->is_int()->get_con(), "must be"); 3650 // Undo the effects of the previous loop trip, which swallowed st: 3651 intcon[0] = 0; // undo store_constant() 3652 set_req(i-1, st); // undo set_req(i, zmem) 3653 nodes[j] = NULL; // undo nodes[j] = st 3654 --old_subword; // undo ++old_subword 3655 } 3656 continue; // This StoreI is already optimal. 3657 } 3658 } 3659 3660 // This store is not needed. 3661 set_req(i, zmem); 3662 nodes[j] = st; // record for the moment 3663 if (st_size < BytesPerLong) // something has changed 3664 ++old_subword; // includes int/float, but who's counting... 3665 else ++old_long; 3666 } 3667 3668 if ((old_subword + old_long) == 0) 3669 return; // nothing more to do 3670 3671 //// Pass B: Convert any non-zero tiles into optimal constant stores. 3672 // Be sure to insert them before overlapping non-constant stores. 3673 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.) 3674 for (int j = 0; j < num_tiles; j++) { 3675 jlong con = tiles[j]; 3676 jlong init = inits[j]; 3677 if (con == 0) continue; 3678 jint con0, con1; // split the constant, address-wise 3679 jint init0, init1; // split the init map, address-wise 3680 { union { jlong con; jint intcon[2]; } u; 3681 u.con = con; 3682 con0 = u.intcon[0]; 3683 con1 = u.intcon[1]; 3684 u.con = init; 3685 init0 = u.intcon[0]; 3686 init1 = u.intcon[1]; 3687 } 3688 3689 Node* old = nodes[j]; 3690 assert(old != NULL, "need the prior store"); 3691 intptr_t offset = (j * BytesPerLong); 3692 3693 bool split = !Matcher::isSimpleConstant64(con); 3694 3695 if (offset < header_size) { 3696 assert(offset + BytesPerInt >= header_size, "second int counts"); 3697 assert(*(jint*)&tiles[j] == 0, "junk in header"); 3698 split = true; // only the second word counts 3699 // Example: int a[] = { 42 ... } 3700 } else if (con0 == 0 && init0 == -1) { 3701 split = true; // first word is covered by full inits 3702 // Example: int a[] = { ... foo(), 42 ... } 3703 } else if (con1 == 0 && init1 == -1) { 3704 split = true; // second word is covered by full inits 3705 // Example: int a[] = { ... 42, foo() ... } 3706 } 3707 3708 // Here's a case where init0 is neither 0 nor -1: 3709 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... } 3710 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF. 3711 // In this case the tile is not split; it is (jlong)42. 3712 // The big tile is stored down, and then the foo() value is inserted. 3713 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.) 3714 3715 Node* ctl = old->in(MemNode::Control); 3716 Node* adr = make_raw_address(offset, phase); 3717 const TypePtr* atp = TypeRawPtr::BOTTOM; 3718 3719 // One or two coalesced stores to plop down. 3720 Node* st[2]; 3721 intptr_t off[2]; 3722 int nst = 0; 3723 if (!split) { 3724 ++new_long; 3725 off[nst] = offset; 3726 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp, 3727 phase->longcon(con), T_LONG, MemNode::unordered); 3728 } else { 3729 // Omit either if it is a zero. 3730 if (con0 != 0) { 3731 ++new_int; 3732 off[nst] = offset; 3733 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp, 3734 phase->intcon(con0), T_INT, MemNode::unordered); 3735 } 3736 if (con1 != 0) { 3737 ++new_int; 3738 offset += BytesPerInt; 3739 adr = make_raw_address(offset, phase); 3740 off[nst] = offset; 3741 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp, 3742 phase->intcon(con1), T_INT, MemNode::unordered); 3743 } 3744 } 3745 3746 // Insert second store first, then the first before the second. 3747 // Insert each one just before any overlapping non-constant stores. 3748 while (nst > 0) { 3749 Node* st1 = st[--nst]; 3750 C->copy_node_notes_to(st1, old); 3751 st1 = phase->transform(st1); 3752 offset = off[nst]; 3753 assert(offset >= header_size, "do not smash header"); 3754 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase); 3755 guarantee(ins_idx != 0, "must re-insert constant store"); 3756 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap 3757 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem) 3758 set_req(--ins_idx, st1); 3759 else 3760 ins_req(ins_idx, st1); 3761 } 3762 } 3763 3764 if (PrintCompilation && WizardMode) 3765 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long", 3766 old_subword, old_long, new_int, new_long); 3767 if (C->log() != NULL) 3768 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'", 3769 old_subword, old_long, new_int, new_long); 3770 3771 // Clean up any remaining occurrences of zmem: 3772 remove_extra_zeroes(); 3773 } 3774 3775 // Explore forward from in(start) to find the first fully initialized 3776 // word, and return its offset. Skip groups of subword stores which 3777 // together initialize full words. If in(start) is itself part of a 3778 // fully initialized word, return the offset of in(start). If there 3779 // are no following full-word stores, or if something is fishy, return 3780 // a negative value. 3781 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) { 3782 int int_map = 0; 3783 intptr_t int_map_off = 0; 3784 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for 3785 3786 for (uint i = start, limit = req(); i < limit; i++) { 3787 Node* st = in(i); 3788 3789 intptr_t st_off = get_store_offset(st, phase); 3790 if (st_off < 0) break; // return conservative answer 3791 3792 int st_size = st->as_Store()->memory_size(); 3793 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) { 3794 return st_off; // we found a complete word init 3795 } 3796 3797 // update the map: 3798 3799 intptr_t this_int_off = align_size_down(st_off, BytesPerInt); 3800 if (this_int_off != int_map_off) { 3801 // reset the map: 3802 int_map = 0; 3803 int_map_off = this_int_off; 3804 } 3805 3806 int subword_off = st_off - this_int_off; 3807 int_map |= right_n_bits(st_size) << subword_off; 3808 if ((int_map & FULL_MAP) == FULL_MAP) { 3809 return this_int_off; // we found a complete word init 3810 } 3811 3812 // Did this store hit or cross the word boundary? 3813 intptr_t next_int_off = align_size_down(st_off + st_size, BytesPerInt); 3814 if (next_int_off == this_int_off + BytesPerInt) { 3815 // We passed the current int, without fully initializing it. 3816 int_map_off = next_int_off; 3817 int_map >>= BytesPerInt; 3818 } else if (next_int_off > this_int_off + BytesPerInt) { 3819 // We passed the current and next int. 3820 return this_int_off + BytesPerInt; 3821 } 3822 } 3823 3824 return -1; 3825 } 3826 3827 3828 // Called when the associated AllocateNode is expanded into CFG. 3829 // At this point, we may perform additional optimizations. 3830 // Linearize the stores by ascending offset, to make memory 3831 // activity as coherent as possible. 3832 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr, 3833 intptr_t header_size, 3834 Node* size_in_bytes, 3835 PhaseGVN* phase) { 3836 assert(!is_complete(), "not already complete"); 3837 assert(stores_are_sane(phase), ""); 3838 assert(allocation() != NULL, "must be present"); 3839 3840 remove_extra_zeroes(); 3841 3842 if (ReduceFieldZeroing || ReduceBulkZeroing) 3843 // reduce instruction count for common initialization patterns 3844 coalesce_subword_stores(header_size, size_in_bytes, phase); 3845 3846 Node* zmem = zero_memory(); // initially zero memory state 3847 Node* inits = zmem; // accumulating a linearized chain of inits 3848 #ifdef ASSERT 3849 intptr_t first_offset = allocation()->minimum_header_size(); 3850 intptr_t last_init_off = first_offset; // previous init offset 3851 intptr_t last_init_end = first_offset; // previous init offset+size 3852 intptr_t last_tile_end = first_offset; // previous tile offset+size 3853 #endif 3854 intptr_t zeroes_done = header_size; 3855 3856 bool do_zeroing = true; // we might give up if inits are very sparse 3857 int big_init_gaps = 0; // how many large gaps have we seen? 3858 3859 if (ZeroTLAB) do_zeroing = false; 3860 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false; 3861 3862 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) { 3863 Node* st = in(i); 3864 intptr_t st_off = get_store_offset(st, phase); 3865 if (st_off < 0) 3866 break; // unknown junk in the inits 3867 if (st->in(MemNode::Memory) != zmem) 3868 break; // complicated store chains somehow in list 3869 3870 int st_size = st->as_Store()->memory_size(); 3871 intptr_t next_init_off = st_off + st_size; 3872 3873 if (do_zeroing && zeroes_done < next_init_off) { 3874 // See if this store needs a zero before it or under it. 3875 intptr_t zeroes_needed = st_off; 3876 3877 if (st_size < BytesPerInt) { 3878 // Look for subword stores which only partially initialize words. 3879 // If we find some, we must lay down some word-level zeroes first, 3880 // underneath the subword stores. 3881 // 3882 // Examples: 3883 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s 3884 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y 3885 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z 3886 // 3887 // Note: coalesce_subword_stores may have already done this, 3888 // if it was prompted by constant non-zero subword initializers. 3889 // But this case can still arise with non-constant stores. 3890 3891 intptr_t next_full_store = find_next_fullword_store(i, phase); 3892 3893 // In the examples above: 3894 // in(i) p q r s x y z 3895 // st_off 12 13 14 15 12 13 14 3896 // st_size 1 1 1 1 1 1 1 3897 // next_full_s. 12 16 16 16 16 16 16 3898 // z's_done 12 16 16 16 12 16 12 3899 // z's_needed 12 16 16 16 16 16 16 3900 // zsize 0 0 0 0 4 0 4 3901 if (next_full_store < 0) { 3902 // Conservative tack: Zero to end of current word. 3903 zeroes_needed = align_size_up(zeroes_needed, BytesPerInt); 3904 } else { 3905 // Zero to beginning of next fully initialized word. 3906 // Or, don't zero at all, if we are already in that word. 3907 assert(next_full_store >= zeroes_needed, "must go forward"); 3908 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary"); 3909 zeroes_needed = next_full_store; 3910 } 3911 } 3912 3913 if (zeroes_needed > zeroes_done) { 3914 intptr_t zsize = zeroes_needed - zeroes_done; 3915 // Do some incremental zeroing on rawmem, in parallel with inits. 3916 zeroes_done = align_size_down(zeroes_done, BytesPerInt); 3917 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr, 3918 zeroes_done, zeroes_needed, 3919 phase); 3920 zeroes_done = zeroes_needed; 3921 if (zsize > Matcher::init_array_short_size && ++big_init_gaps > 2) 3922 do_zeroing = false; // leave the hole, next time 3923 } 3924 } 3925 3926 // Collect the store and move on: 3927 st->set_req(MemNode::Memory, inits); 3928 inits = st; // put it on the linearized chain 3929 set_req(i, zmem); // unhook from previous position 3930 3931 if (zeroes_done == st_off) 3932 zeroes_done = next_init_off; 3933 3934 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any"); 3935 3936 #ifdef ASSERT 3937 // Various order invariants. Weaker than stores_are_sane because 3938 // a large constant tile can be filled in by smaller non-constant stores. 3939 assert(st_off >= last_init_off, "inits do not reverse"); 3940 last_init_off = st_off; 3941 const Type* val = NULL; 3942 if (st_size >= BytesPerInt && 3943 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() && 3944 (int)val->basic_type() < (int)T_OBJECT) { 3945 assert(st_off >= last_tile_end, "tiles do not overlap"); 3946 assert(st_off >= last_init_end, "tiles do not overwrite inits"); 3947 last_tile_end = MAX2(last_tile_end, next_init_off); 3948 } else { 3949 intptr_t st_tile_end = align_size_up(next_init_off, BytesPerLong); 3950 assert(st_tile_end >= last_tile_end, "inits stay with tiles"); 3951 assert(st_off >= last_init_end, "inits do not overlap"); 3952 last_init_end = next_init_off; // it's a non-tile 3953 } 3954 #endif //ASSERT 3955 } 3956 3957 remove_extra_zeroes(); // clear out all the zmems left over 3958 add_req(inits); 3959 3960 if (!ZeroTLAB) { 3961 // If anything remains to be zeroed, zero it all now. 3962 zeroes_done = align_size_down(zeroes_done, BytesPerInt); 3963 // if it is the last unused 4 bytes of an instance, forget about it 3964 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint); 3965 if (zeroes_done + BytesPerLong >= size_limit) { 3966 assert(allocation() != NULL, ""); 3967 if (allocation()->Opcode() == Op_Allocate) { 3968 Node* klass_node = allocation()->in(AllocateNode::KlassNode); 3969 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass(); 3970 if (zeroes_done == k->layout_helper()) 3971 zeroes_done = size_limit; 3972 } 3973 } 3974 if (zeroes_done < size_limit) { 3975 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr, 3976 zeroes_done, size_in_bytes, phase); 3977 } 3978 } 3979 3980 set_complete(phase); 3981 return rawmem; 3982 } 3983 3984 3985 #ifdef ASSERT 3986 bool InitializeNode::stores_are_sane(PhaseTransform* phase) { 3987 if (is_complete()) 3988 return true; // stores could be anything at this point 3989 assert(allocation() != NULL, "must be present"); 3990 intptr_t last_off = allocation()->minimum_header_size(); 3991 for (uint i = InitializeNode::RawStores; i < req(); i++) { 3992 Node* st = in(i); 3993 intptr_t st_off = get_store_offset(st, phase); 3994 if (st_off < 0) continue; // ignore dead garbage 3995 if (last_off > st_off) { 3996 tty->print_cr("*** bad store offset at %d: " INTX_FORMAT " > " INTX_FORMAT, i, last_off, st_off); 3997 this->dump(2); 3998 assert(false, "ascending store offsets"); 3999 return false; 4000 } 4001 last_off = st_off + st->as_Store()->memory_size(); 4002 } 4003 return true; 4004 } 4005 #endif //ASSERT 4006 4007 4008 4009 4010 //============================MergeMemNode===================================== 4011 // 4012 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several 4013 // contributing store or call operations. Each contributor provides the memory 4014 // state for a particular "alias type" (see Compile::alias_type). For example, 4015 // if a MergeMem has an input X for alias category #6, then any memory reference 4016 // to alias category #6 may use X as its memory state input, as an exact equivalent 4017 // to using the MergeMem as a whole. 4018 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p) 4019 // 4020 // (Here, the <N> notation gives the index of the relevant adr_type.) 4021 // 4022 // In one special case (and more cases in the future), alias categories overlap. 4023 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory 4024 // states. Therefore, if a MergeMem has only one contributing input W for Bot, 4025 // it is exactly equivalent to that state W: 4026 // MergeMem(<Bot>: W) <==> W 4027 // 4028 // Usually, the merge has more than one input. In that case, where inputs 4029 // overlap (i.e., one is Bot), the narrower alias type determines the memory 4030 // state for that type, and the wider alias type (Bot) fills in everywhere else: 4031 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p) 4032 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p) 4033 // 4034 // A merge can take a "wide" memory state as one of its narrow inputs. 4035 // This simply means that the merge observes out only the relevant parts of 4036 // the wide input. That is, wide memory states arriving at narrow merge inputs 4037 // are implicitly "filtered" or "sliced" as necessary. (This is rare.) 4038 // 4039 // These rules imply that MergeMem nodes may cascade (via their <Bot> links), 4040 // and that memory slices "leak through": 4041 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y) 4042 // 4043 // But, in such a cascade, repeated memory slices can "block the leak": 4044 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y') 4045 // 4046 // In the last example, Y is not part of the combined memory state of the 4047 // outermost MergeMem. The system must, of course, prevent unschedulable 4048 // memory states from arising, so you can be sure that the state Y is somehow 4049 // a precursor to state Y'. 4050 // 4051 // 4052 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array 4053 // of each MergeMemNode array are exactly the numerical alias indexes, including 4054 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions 4055 // Compile::alias_type (and kin) produce and manage these indexes. 4056 // 4057 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node. 4058 // (Note that this provides quick access to the top node inside MergeMem methods, 4059 // without the need to reach out via TLS to Compile::current.) 4060 // 4061 // As a consequence of what was just described, a MergeMem that represents a full 4062 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state, 4063 // containing all alias categories. 4064 // 4065 // MergeMem nodes never (?) have control inputs, so in(0) is NULL. 4066 // 4067 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either 4068 // a memory state for the alias type <N>, or else the top node, meaning that 4069 // there is no particular input for that alias type. Note that the length of 4070 // a MergeMem is variable, and may be extended at any time to accommodate new 4071 // memory states at larger alias indexes. When merges grow, they are of course 4072 // filled with "top" in the unused in() positions. 4073 // 4074 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable. 4075 // (Top was chosen because it works smoothly with passes like GCM.) 4076 // 4077 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is 4078 // the type of random VM bits like TLS references.) Since it is always the 4079 // first non-Bot memory slice, some low-level loops use it to initialize an 4080 // index variable: for (i = AliasIdxRaw; i < req(); i++). 4081 // 4082 // 4083 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns 4084 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns 4085 // the memory state for alias type <N>, or (if there is no particular slice at <N>, 4086 // it returns the base memory. To prevent bugs, memory_at does not accept <Top> 4087 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over 4088 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited. 4089 // 4090 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't 4091 // really that different from the other memory inputs. An abbreviation called 4092 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy. 4093 // 4094 // 4095 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent 4096 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi 4097 // that "emerges though" the base memory will be marked as excluding the alias types 4098 // of the other (narrow-memory) copies which "emerged through" the narrow edges: 4099 // 4100 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y)) 4101 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y)) 4102 // 4103 // This strange "subtraction" effect is necessary to ensure IGVN convergence. 4104 // (It is currently unimplemented.) As you can see, the resulting merge is 4105 // actually a disjoint union of memory states, rather than an overlay. 4106 // 4107 4108 //------------------------------MergeMemNode----------------------------------- 4109 Node* MergeMemNode::make_empty_memory() { 4110 Node* empty_memory = (Node*) Compile::current()->top(); 4111 assert(empty_memory->is_top(), "correct sentinel identity"); 4112 return empty_memory; 4113 } 4114 4115 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) { 4116 init_class_id(Class_MergeMem); 4117 // all inputs are nullified in Node::Node(int) 4118 // set_input(0, NULL); // no control input 4119 4120 // Initialize the edges uniformly to top, for starters. 4121 Node* empty_mem = make_empty_memory(); 4122 for (uint i = Compile::AliasIdxTop; i < req(); i++) { 4123 init_req(i,empty_mem); 4124 } 4125 assert(empty_memory() == empty_mem, ""); 4126 4127 if( new_base != NULL && new_base->is_MergeMem() ) { 4128 MergeMemNode* mdef = new_base->as_MergeMem(); 4129 assert(mdef->empty_memory() == empty_mem, "consistent sentinels"); 4130 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) { 4131 mms.set_memory(mms.memory2()); 4132 } 4133 assert(base_memory() == mdef->base_memory(), ""); 4134 } else { 4135 set_base_memory(new_base); 4136 } 4137 } 4138 4139 // Make a new, untransformed MergeMem with the same base as 'mem'. 4140 // If mem is itself a MergeMem, populate the result with the same edges. 4141 MergeMemNode* MergeMemNode::make(Node* mem) { 4142 return new MergeMemNode(mem); 4143 } 4144 4145 //------------------------------cmp-------------------------------------------- 4146 uint MergeMemNode::hash() const { return NO_HASH; } 4147 uint MergeMemNode::cmp( const Node &n ) const { 4148 return (&n == this); // Always fail except on self 4149 } 4150 4151 //------------------------------Identity--------------------------------------- 4152 Node* MergeMemNode::Identity(PhaseTransform *phase) { 4153 // Identity if this merge point does not record any interesting memory 4154 // disambiguations. 4155 Node* base_mem = base_memory(); 4156 Node* empty_mem = empty_memory(); 4157 if (base_mem != empty_mem) { // Memory path is not dead? 4158 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 4159 Node* mem = in(i); 4160 if (mem != empty_mem && mem != base_mem) { 4161 return this; // Many memory splits; no change 4162 } 4163 } 4164 } 4165 return base_mem; // No memory splits; ID on the one true input 4166 } 4167 4168 //------------------------------Ideal------------------------------------------ 4169 // This method is invoked recursively on chains of MergeMem nodes 4170 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) { 4171 // Remove chain'd MergeMems 4172 // 4173 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted 4174 // relative to the "in(Bot)". Since we are patching both at the same time, 4175 // we have to be careful to read each "in(i)" relative to the old "in(Bot)", 4176 // but rewrite each "in(i)" relative to the new "in(Bot)". 4177 Node *progress = NULL; 4178 4179 4180 Node* old_base = base_memory(); 4181 Node* empty_mem = empty_memory(); 4182 if (old_base == empty_mem) 4183 return NULL; // Dead memory path. 4184 4185 MergeMemNode* old_mbase; 4186 if (old_base != NULL && old_base->is_MergeMem()) 4187 old_mbase = old_base->as_MergeMem(); 4188 else 4189 old_mbase = NULL; 4190 Node* new_base = old_base; 4191 4192 // simplify stacked MergeMems in base memory 4193 if (old_mbase) new_base = old_mbase->base_memory(); 4194 4195 // the base memory might contribute new slices beyond my req() 4196 if (old_mbase) grow_to_match(old_mbase); 4197 4198 // Look carefully at the base node if it is a phi. 4199 PhiNode* phi_base; 4200 if (new_base != NULL && new_base->is_Phi()) 4201 phi_base = new_base->as_Phi(); 4202 else 4203 phi_base = NULL; 4204 4205 Node* phi_reg = NULL; 4206 uint phi_len = (uint)-1; 4207 if (phi_base != NULL && !phi_base->is_copy()) { 4208 // do not examine phi if degraded to a copy 4209 phi_reg = phi_base->region(); 4210 phi_len = phi_base->req(); 4211 // see if the phi is unfinished 4212 for (uint i = 1; i < phi_len; i++) { 4213 if (phi_base->in(i) == NULL) { 4214 // incomplete phi; do not look at it yet! 4215 phi_reg = NULL; 4216 phi_len = (uint)-1; 4217 break; 4218 } 4219 } 4220 } 4221 4222 // Note: We do not call verify_sparse on entry, because inputs 4223 // can normalize to the base_memory via subsume_node or similar 4224 // mechanisms. This method repairs that damage. 4225 4226 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels"); 4227 4228 // Look at each slice. 4229 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 4230 Node* old_in = in(i); 4231 // calculate the old memory value 4232 Node* old_mem = old_in; 4233 if (old_mem == empty_mem) old_mem = old_base; 4234 assert(old_mem == memory_at(i), ""); 4235 4236 // maybe update (reslice) the old memory value 4237 4238 // simplify stacked MergeMems 4239 Node* new_mem = old_mem; 4240 MergeMemNode* old_mmem; 4241 if (old_mem != NULL && old_mem->is_MergeMem()) 4242 old_mmem = old_mem->as_MergeMem(); 4243 else 4244 old_mmem = NULL; 4245 if (old_mmem == this) { 4246 // This can happen if loops break up and safepoints disappear. 4247 // A merge of BotPtr (default) with a RawPtr memory derived from a 4248 // safepoint can be rewritten to a merge of the same BotPtr with 4249 // the BotPtr phi coming into the loop. If that phi disappears 4250 // also, we can end up with a self-loop of the mergemem. 4251 // In general, if loops degenerate and memory effects disappear, 4252 // a mergemem can be left looking at itself. This simply means 4253 // that the mergemem's default should be used, since there is 4254 // no longer any apparent effect on this slice. 4255 // Note: If a memory slice is a MergeMem cycle, it is unreachable 4256 // from start. Update the input to TOP. 4257 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base; 4258 } 4259 else if (old_mmem != NULL) { 4260 new_mem = old_mmem->memory_at(i); 4261 } 4262 // else preceding memory was not a MergeMem 4263 4264 // replace equivalent phis (unfortunately, they do not GVN together) 4265 if (new_mem != NULL && new_mem != new_base && 4266 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) { 4267 if (new_mem->is_Phi()) { 4268 PhiNode* phi_mem = new_mem->as_Phi(); 4269 for (uint i = 1; i < phi_len; i++) { 4270 if (phi_base->in(i) != phi_mem->in(i)) { 4271 phi_mem = NULL; 4272 break; 4273 } 4274 } 4275 if (phi_mem != NULL) { 4276 // equivalent phi nodes; revert to the def 4277 new_mem = new_base; 4278 } 4279 } 4280 } 4281 4282 // maybe store down a new value 4283 Node* new_in = new_mem; 4284 if (new_in == new_base) new_in = empty_mem; 4285 4286 if (new_in != old_in) { 4287 // Warning: Do not combine this "if" with the previous "if" 4288 // A memory slice might have be be rewritten even if it is semantically 4289 // unchanged, if the base_memory value has changed. 4290 set_req(i, new_in); 4291 progress = this; // Report progress 4292 } 4293 } 4294 4295 if (new_base != old_base) { 4296 set_req(Compile::AliasIdxBot, new_base); 4297 // Don't use set_base_memory(new_base), because we need to update du. 4298 assert(base_memory() == new_base, ""); 4299 progress = this; 4300 } 4301 4302 if( base_memory() == this ) { 4303 // a self cycle indicates this memory path is dead 4304 set_req(Compile::AliasIdxBot, empty_mem); 4305 } 4306 4307 // Resolve external cycles by calling Ideal on a MergeMem base_memory 4308 // Recursion must occur after the self cycle check above 4309 if( base_memory()->is_MergeMem() ) { 4310 MergeMemNode *new_mbase = base_memory()->as_MergeMem(); 4311 Node *m = phase->transform(new_mbase); // Rollup any cycles 4312 if( m != NULL && (m->is_top() || 4313 m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem) ) { 4314 // propagate rollup of dead cycle to self 4315 set_req(Compile::AliasIdxBot, empty_mem); 4316 } 4317 } 4318 4319 if( base_memory() == empty_mem ) { 4320 progress = this; 4321 // Cut inputs during Parse phase only. 4322 // During Optimize phase a dead MergeMem node will be subsumed by Top. 4323 if( !can_reshape ) { 4324 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 4325 if( in(i) != empty_mem ) { set_req(i, empty_mem); } 4326 } 4327 } 4328 } 4329 4330 if( !progress && base_memory()->is_Phi() && can_reshape ) { 4331 // Check if PhiNode::Ideal's "Split phis through memory merges" 4332 // transform should be attempted. Look for this->phi->this cycle. 4333 uint merge_width = req(); 4334 if (merge_width > Compile::AliasIdxRaw) { 4335 PhiNode* phi = base_memory()->as_Phi(); 4336 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in 4337 if (phi->in(i) == this) { 4338 phase->is_IterGVN()->_worklist.push(phi); 4339 break; 4340 } 4341 } 4342 } 4343 } 4344 4345 assert(progress || verify_sparse(), "please, no dups of base"); 4346 return progress; 4347 } 4348 4349 //-------------------------set_base_memory------------------------------------- 4350 void MergeMemNode::set_base_memory(Node *new_base) { 4351 Node* empty_mem = empty_memory(); 4352 set_req(Compile::AliasIdxBot, new_base); 4353 assert(memory_at(req()) == new_base, "must set default memory"); 4354 // Clear out other occurrences of new_base: 4355 if (new_base != empty_mem) { 4356 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 4357 if (in(i) == new_base) set_req(i, empty_mem); 4358 } 4359 } 4360 } 4361 4362 //------------------------------out_RegMask------------------------------------ 4363 const RegMask &MergeMemNode::out_RegMask() const { 4364 return RegMask::Empty; 4365 } 4366 4367 //------------------------------dump_spec-------------------------------------- 4368 #ifndef PRODUCT 4369 void MergeMemNode::dump_spec(outputStream *st) const { 4370 st->print(" {"); 4371 Node* base_mem = base_memory(); 4372 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) { 4373 Node* mem = (in(i) != NULL) ? memory_at(i) : base_mem; 4374 if (mem == base_mem) { st->print(" -"); continue; } 4375 st->print( " N%d:", mem->_idx ); 4376 Compile::current()->get_adr_type(i)->dump_on(st); 4377 } 4378 st->print(" }"); 4379 } 4380 #endif // !PRODUCT 4381 4382 4383 #ifdef ASSERT 4384 static bool might_be_same(Node* a, Node* b) { 4385 if (a == b) return true; 4386 if (!(a->is_Phi() || b->is_Phi())) return false; 4387 // phis shift around during optimization 4388 return true; // pretty stupid... 4389 } 4390 4391 // verify a narrow slice (either incoming or outgoing) 4392 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) { 4393 if (!VerifyAliases) return; // don't bother to verify unless requested 4394 if (is_error_reported()) return; // muzzle asserts when debugging an error 4395 if (Node::in_dump()) return; // muzzle asserts when printing 4396 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel"); 4397 assert(n != NULL, ""); 4398 // Elide intervening MergeMem's 4399 while (n->is_MergeMem()) { 4400 n = n->as_MergeMem()->memory_at(alias_idx); 4401 } 4402 Compile* C = Compile::current(); 4403 const TypePtr* n_adr_type = n->adr_type(); 4404 if (n == m->empty_memory()) { 4405 // Implicit copy of base_memory() 4406 } else if (n_adr_type != TypePtr::BOTTOM) { 4407 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type"); 4408 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice"); 4409 } else { 4410 // A few places like make_runtime_call "know" that VM calls are narrow, 4411 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM. 4412 bool expected_wide_mem = false; 4413 if (n == m->base_memory()) { 4414 expected_wide_mem = true; 4415 } else if (alias_idx == Compile::AliasIdxRaw || 4416 n == m->memory_at(Compile::AliasIdxRaw)) { 4417 expected_wide_mem = true; 4418 } else if (!C->alias_type(alias_idx)->is_rewritable()) { 4419 // memory can "leak through" calls on channels that 4420 // are write-once. Allow this also. 4421 expected_wide_mem = true; 4422 } 4423 assert(expected_wide_mem, "expected narrow slice replacement"); 4424 } 4425 } 4426 #else // !ASSERT 4427 #define verify_memory_slice(m,i,n) (void)(0) // PRODUCT version is no-op 4428 #endif 4429 4430 4431 //-----------------------------memory_at--------------------------------------- 4432 Node* MergeMemNode::memory_at(uint alias_idx) const { 4433 assert(alias_idx >= Compile::AliasIdxRaw || 4434 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0, 4435 "must avoid base_memory and AliasIdxTop"); 4436 4437 // Otherwise, it is a narrow slice. 4438 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory(); 4439 Compile *C = Compile::current(); 4440 if (is_empty_memory(n)) { 4441 // the array is sparse; empty slots are the "top" node 4442 n = base_memory(); 4443 assert(Node::in_dump() 4444 || n == NULL || n->bottom_type() == Type::TOP 4445 || n->adr_type() == NULL // address is TOP 4446 || n->adr_type() == TypePtr::BOTTOM 4447 || n->adr_type() == TypeRawPtr::BOTTOM 4448 || Compile::current()->AliasLevel() == 0, 4449 "must be a wide memory"); 4450 // AliasLevel == 0 if we are organizing the memory states manually. 4451 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM. 4452 } else { 4453 // make sure the stored slice is sane 4454 #ifdef ASSERT 4455 if (is_error_reported() || Node::in_dump()) { 4456 } else if (might_be_same(n, base_memory())) { 4457 // Give it a pass: It is a mostly harmless repetition of the base. 4458 // This can arise normally from node subsumption during optimization. 4459 } else { 4460 verify_memory_slice(this, alias_idx, n); 4461 } 4462 #endif 4463 } 4464 return n; 4465 } 4466 4467 //---------------------------set_memory_at------------------------------------- 4468 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) { 4469 verify_memory_slice(this, alias_idx, n); 4470 Node* empty_mem = empty_memory(); 4471 if (n == base_memory()) n = empty_mem; // collapse default 4472 uint need_req = alias_idx+1; 4473 if (req() < need_req) { 4474 if (n == empty_mem) return; // already the default, so do not grow me 4475 // grow the sparse array 4476 do { 4477 add_req(empty_mem); 4478 } while (req() < need_req); 4479 } 4480 set_req( alias_idx, n ); 4481 } 4482 4483 4484 4485 //--------------------------iteration_setup------------------------------------ 4486 void MergeMemNode::iteration_setup(const MergeMemNode* other) { 4487 if (other != NULL) { 4488 grow_to_match(other); 4489 // invariant: the finite support of mm2 is within mm->req() 4490 #ifdef ASSERT 4491 for (uint i = req(); i < other->req(); i++) { 4492 assert(other->is_empty_memory(other->in(i)), "slice left uncovered"); 4493 } 4494 #endif 4495 } 4496 // Replace spurious copies of base_memory by top. 4497 Node* base_mem = base_memory(); 4498 if (base_mem != NULL && !base_mem->is_top()) { 4499 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) { 4500 if (in(i) == base_mem) 4501 set_req(i, empty_memory()); 4502 } 4503 } 4504 } 4505 4506 //---------------------------grow_to_match------------------------------------- 4507 void MergeMemNode::grow_to_match(const MergeMemNode* other) { 4508 Node* empty_mem = empty_memory(); 4509 assert(other->is_empty_memory(empty_mem), "consistent sentinels"); 4510 // look for the finite support of the other memory 4511 for (uint i = other->req(); --i >= req(); ) { 4512 if (other->in(i) != empty_mem) { 4513 uint new_len = i+1; 4514 while (req() < new_len) add_req(empty_mem); 4515 break; 4516 } 4517 } 4518 } 4519 4520 //---------------------------verify_sparse------------------------------------- 4521 #ifndef PRODUCT 4522 bool MergeMemNode::verify_sparse() const { 4523 assert(is_empty_memory(make_empty_memory()), "sane sentinel"); 4524 Node* base_mem = base_memory(); 4525 // The following can happen in degenerate cases, since empty==top. 4526 if (is_empty_memory(base_mem)) return true; 4527 for (uint i = Compile::AliasIdxRaw; i < req(); i++) { 4528 assert(in(i) != NULL, "sane slice"); 4529 if (in(i) == base_mem) return false; // should have been the sentinel value! 4530 } 4531 return true; 4532 } 4533 4534 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) { 4535 Node* n; 4536 n = mm->in(idx); 4537 if (mem == n) return true; // might be empty_memory() 4538 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx); 4539 if (mem == n) return true; 4540 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) { 4541 if (mem == n) return true; 4542 if (n == NULL) break; 4543 } 4544 return false; 4545 } 4546 #endif // !PRODUCT