1 /* 2 * Copyright (c) 2011, 2013, 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 "opto/loopnode.hpp" 27 #include "opto/addnode.hpp" 28 #include "opto/callnode.hpp" 29 #include "opto/connode.hpp" 30 #include "opto/loopnode.hpp" 31 #include "opto/mulnode.hpp" 32 #include "opto/rootnode.hpp" 33 #include "opto/subnode.hpp" 34 35 /* 36 * The general idea of Loop Predication is to insert a predicate on the entry 37 * path to a loop, and raise a uncommon trap if the check of the condition fails. 38 * The condition checks are promoted from inside the loop body, and thus 39 * the checks inside the loop could be eliminated. Currently, loop predication 40 * optimization has been applied to remove array range check and loop invariant 41 * checks (such as null checks). 42 */ 43 44 //-------------------------------register_control------------------------- 45 void PhaseIdealLoop::register_control(Node* n, IdealLoopTree *loop, Node* pred) { 46 assert(n->is_CFG(), "must be control node"); 47 _igvn.register_new_node_with_optimizer(n); 48 loop->_body.push(n); 49 set_loop(n, loop); 50 // When called from beautify_loops() idom is not constructed yet. 51 if (_idom != NULL) { 52 set_idom(n, pred, dom_depth(pred)); 53 } 54 } 55 56 //------------------------------create_new_if_for_predicate------------------------ 57 // create a new if above the uct_if_pattern for the predicate to be promoted. 58 // 59 // before after 60 // ---------- ---------- 61 // ctrl ctrl 62 // | | 63 // | | 64 // v v 65 // iff new_iff 66 // / \ / \ 67 // / \ / \ 68 // v v v v 69 // uncommon_proj cont_proj if_uct if_cont 70 // \ | | | | 71 // \ | | | | 72 // v v v | v 73 // rgn loop | iff 74 // | | / \ 75 // | | / \ 76 // v | v v 77 // uncommon_trap | uncommon_proj cont_proj 78 // \ \ | | 79 // \ \ | | 80 // v v v v 81 // rgn loop 82 // | 83 // | 84 // v 85 // uncommon_trap 86 // 87 // 88 // We will create a region to guard the uct call if there is no one there. 89 // The true projecttion (if_cont) of the new_iff is returned. 90 // This code is also used to clone predicates to clonned loops. 91 ProjNode* PhaseIdealLoop::create_new_if_for_predicate(ProjNode* cont_proj, Node* new_entry, 92 Deoptimization::DeoptReason reason) { 93 assert(cont_proj->is_uncommon_trap_if_pattern(reason), "must be a uct if pattern!"); 94 IfNode* iff = cont_proj->in(0)->as_If(); 95 96 ProjNode *uncommon_proj = iff->proj_out(1 - cont_proj->_con); 97 Node *rgn = uncommon_proj->unique_ctrl_out(); 98 assert(rgn->is_Region() || rgn->is_Call(), "must be a region or call uct"); 99 100 uint proj_index = 1; // region's edge corresponding to uncommon_proj 101 if (!rgn->is_Region()) { // create a region to guard the call 102 assert(rgn->is_Call(), "must be call uct"); 103 CallNode* call = rgn->as_Call(); 104 IdealLoopTree* loop = get_loop(call); 105 rgn = new (C) RegionNode(1); 106 rgn->add_req(uncommon_proj); 107 register_control(rgn, loop, uncommon_proj); 108 _igvn.hash_delete(call); 109 call->set_req(0, rgn); 110 // When called from beautify_loops() idom is not constructed yet. 111 if (_idom != NULL) { 112 set_idom(call, rgn, dom_depth(rgn)); 113 } 114 } else { 115 // Find region's edge corresponding to uncommon_proj 116 for (; proj_index < rgn->req(); proj_index++) 117 if (rgn->in(proj_index) == uncommon_proj) break; 118 assert(proj_index < rgn->req(), "sanity"); 119 } 120 121 Node* entry = iff->in(0); 122 if (new_entry != NULL) { 123 // Clonning the predicate to new location. 124 entry = new_entry; 125 } 126 // Create new_iff 127 IdealLoopTree* lp = get_loop(entry); 128 IfNode *new_iff = iff->clone()->as_If(); 129 new_iff->set_req(0, entry); 130 register_control(new_iff, lp, entry); 131 Node *if_cont = new (C) IfTrueNode(new_iff); 132 Node *if_uct = new (C) IfFalseNode(new_iff); 133 if (cont_proj->is_IfFalse()) { 134 // Swap 135 Node* tmp = if_uct; if_uct = if_cont; if_cont = tmp; 136 } 137 register_control(if_cont, lp, new_iff); 138 register_control(if_uct, get_loop(rgn), new_iff); 139 140 // if_uct to rgn 141 _igvn.hash_delete(rgn); 142 rgn->add_req(if_uct); 143 // When called from beautify_loops() idom is not constructed yet. 144 if (_idom != NULL) { 145 Node* ridom = idom(rgn); 146 Node* nrdom = dom_lca(ridom, new_iff); 147 set_idom(rgn, nrdom, dom_depth(rgn)); 148 } 149 150 // If rgn has phis add new edges which has the same 151 // value as on original uncommon_proj pass. 152 assert(rgn->in(rgn->req() -1) == if_uct, "new edge should be last"); 153 bool has_phi = false; 154 for (DUIterator_Fast imax, i = rgn->fast_outs(imax); i < imax; i++) { 155 Node* use = rgn->fast_out(i); 156 if (use->is_Phi() && use->outcnt() > 0) { 157 assert(use->in(0) == rgn, ""); 158 _igvn.rehash_node_delayed(use); 159 use->add_req(use->in(proj_index)); 160 has_phi = true; 161 } 162 } 163 assert(!has_phi || rgn->req() > 3, "no phis when region is created"); 164 165 if (new_entry == NULL) { 166 // Attach if_cont to iff 167 _igvn.hash_delete(iff); 168 iff->set_req(0, if_cont); 169 if (_idom != NULL) { 170 set_idom(iff, if_cont, dom_depth(iff)); 171 } 172 } 173 return if_cont->as_Proj(); 174 } 175 176 //------------------------------create_new_if_for_predicate------------------------ 177 // Create a new if below new_entry for the predicate to be cloned (IGVN optimization) 178 ProjNode* PhaseIterGVN::create_new_if_for_predicate(ProjNode* cont_proj, Node* new_entry, 179 Deoptimization::DeoptReason reason) { 180 assert(new_entry != 0, "only used for clone predicate"); 181 assert(cont_proj->is_uncommon_trap_if_pattern(reason), "must be a uct if pattern!"); 182 IfNode* iff = cont_proj->in(0)->as_If(); 183 184 ProjNode *uncommon_proj = iff->proj_out(1 - cont_proj->_con); 185 Node *rgn = uncommon_proj->unique_ctrl_out(); 186 assert(rgn->is_Region() || rgn->is_Call(), "must be a region or call uct"); 187 188 uint proj_index = 1; // region's edge corresponding to uncommon_proj 189 if (!rgn->is_Region()) { // create a region to guard the call 190 assert(rgn->is_Call(), "must be call uct"); 191 CallNode* call = rgn->as_Call(); 192 rgn = new (C) RegionNode(1); 193 register_new_node_with_optimizer(rgn); 194 rgn->add_req(uncommon_proj); 195 hash_delete(call); 196 call->set_req(0, rgn); 197 } else { 198 // Find region's edge corresponding to uncommon_proj 199 for (; proj_index < rgn->req(); proj_index++) 200 if (rgn->in(proj_index) == uncommon_proj) break; 201 assert(proj_index < rgn->req(), "sanity"); 202 } 203 204 // Create new_iff in new location. 205 IfNode *new_iff = iff->clone()->as_If(); 206 new_iff->set_req(0, new_entry); 207 208 register_new_node_with_optimizer(new_iff); 209 Node *if_cont = new (C) IfTrueNode(new_iff); 210 Node *if_uct = new (C) IfFalseNode(new_iff); 211 if (cont_proj->is_IfFalse()) { 212 // Swap 213 Node* tmp = if_uct; if_uct = if_cont; if_cont = tmp; 214 } 215 register_new_node_with_optimizer(if_cont); 216 register_new_node_with_optimizer(if_uct); 217 218 // if_uct to rgn 219 hash_delete(rgn); 220 rgn->add_req(if_uct); 221 222 // If rgn has phis add corresponding new edges which has the same 223 // value as on original uncommon_proj pass. 224 assert(rgn->in(rgn->req() -1) == if_uct, "new edge should be last"); 225 bool has_phi = false; 226 for (DUIterator_Fast imax, i = rgn->fast_outs(imax); i < imax; i++) { 227 Node* use = rgn->fast_out(i); 228 if (use->is_Phi() && use->outcnt() > 0) { 229 rehash_node_delayed(use); 230 use->add_req(use->in(proj_index)); 231 has_phi = true; 232 } 233 } 234 assert(!has_phi || rgn->req() > 3, "no phis when region is created"); 235 236 return if_cont->as_Proj(); 237 } 238 239 //--------------------------clone_predicate----------------------- 240 ProjNode* PhaseIdealLoop::clone_predicate(ProjNode* predicate_proj, Node* new_entry, 241 Deoptimization::DeoptReason reason, 242 PhaseIdealLoop* loop_phase, 243 PhaseIterGVN* igvn) { 244 ProjNode* new_predicate_proj; 245 if (loop_phase != NULL) { 246 new_predicate_proj = loop_phase->create_new_if_for_predicate(predicate_proj, new_entry, reason); 247 } else { 248 new_predicate_proj = igvn->create_new_if_for_predicate(predicate_proj, new_entry, reason); 249 } 250 IfNode* iff = new_predicate_proj->in(0)->as_If(); 251 Node* ctrl = iff->in(0); 252 253 // Match original condition since predicate's projections could be swapped. 254 assert(predicate_proj->in(0)->in(1)->in(1)->Opcode()==Op_Opaque1, "must be"); 255 Node* opq = new (igvn->C) Opaque1Node(igvn->C, predicate_proj->in(0)->in(1)->in(1)->in(1)); 256 igvn->C->add_predicate_opaq(opq); 257 258 Node* bol = new (igvn->C) Conv2BNode(opq); 259 if (loop_phase != NULL) { 260 loop_phase->register_new_node(opq, ctrl); 261 loop_phase->register_new_node(bol, ctrl); 262 } else { 263 igvn->register_new_node_with_optimizer(opq); 264 igvn->register_new_node_with_optimizer(bol); 265 } 266 igvn->hash_delete(iff); 267 iff->set_req(1, bol); 268 return new_predicate_proj; 269 } 270 271 272 //--------------------------clone_loop_predicates----------------------- 273 // Interface from IGVN 274 Node* PhaseIterGVN::clone_loop_predicates(Node* old_entry, Node* new_entry, bool clone_limit_check) { 275 return PhaseIdealLoop::clone_loop_predicates(old_entry, new_entry, clone_limit_check, NULL, this); 276 } 277 278 // Interface from PhaseIdealLoop 279 Node* PhaseIdealLoop::clone_loop_predicates(Node* old_entry, Node* new_entry, bool clone_limit_check) { 280 return clone_loop_predicates(old_entry, new_entry, clone_limit_check, this, &this->_igvn); 281 } 282 283 // Clone loop predicates to cloned loops (peeled, unswitched, split_if). 284 Node* PhaseIdealLoop::clone_loop_predicates(Node* old_entry, Node* new_entry, 285 bool clone_limit_check, 286 PhaseIdealLoop* loop_phase, 287 PhaseIterGVN* igvn) { 288 #ifdef ASSERT 289 if (new_entry == NULL || !(new_entry->is_Proj() || new_entry->is_Region() || new_entry->is_SafePoint())) { 290 if (new_entry != NULL) 291 new_entry->dump(); 292 assert(false, "not IfTrue, IfFalse, Region or SafePoint"); 293 } 294 #endif 295 // Search original predicates 296 Node* entry = old_entry; 297 ProjNode* limit_check_proj = NULL; 298 if (LoopLimitCheck) { 299 limit_check_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check); 300 if (limit_check_proj != NULL) { 301 entry = entry->in(0)->in(0); 302 } 303 } 304 if (UseLoopPredicate) { 305 ProjNode* predicate_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate); 306 if (predicate_proj != NULL) { // right pattern that can be used by loop predication 307 // clone predicate 308 new_entry = clone_predicate(predicate_proj, new_entry, 309 Deoptimization::Reason_predicate, 310 loop_phase, igvn); 311 assert(new_entry != NULL && new_entry->is_Proj(), "IfTrue or IfFalse after clone predicate"); 312 if (TraceLoopPredicate) { 313 tty->print("Loop Predicate cloned: "); 314 debug_only( new_entry->in(0)->dump(); ) 315 } 316 } 317 } 318 if (limit_check_proj != NULL && clone_limit_check) { 319 // Clone loop limit check last to insert it before loop. 320 // Don't clone a limit check which was already finalized 321 // for this counted loop (only one limit check is needed). 322 new_entry = clone_predicate(limit_check_proj, new_entry, 323 Deoptimization::Reason_loop_limit_check, 324 loop_phase, igvn); 325 assert(new_entry != NULL && new_entry->is_Proj(), "IfTrue or IfFalse after clone limit check"); 326 if (TraceLoopLimitCheck) { 327 tty->print("Loop Limit Check cloned: "); 328 debug_only( new_entry->in(0)->dump(); ) 329 } 330 } 331 return new_entry; 332 } 333 334 //--------------------------skip_loop_predicates------------------------------ 335 // Skip related predicates. 336 Node* PhaseIdealLoop::skip_loop_predicates(Node* entry) { 337 Node* predicate = NULL; 338 if (LoopLimitCheck) { 339 predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check); 340 if (predicate != NULL) { 341 entry = entry->in(0)->in(0); 342 } 343 } 344 if (UseLoopPredicate) { 345 predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate); 346 if (predicate != NULL) { // right pattern that can be used by loop predication 347 IfNode* iff = entry->in(0)->as_If(); 348 ProjNode* uncommon_proj = iff->proj_out(1 - entry->as_Proj()->_con); 349 Node* rgn = uncommon_proj->unique_ctrl_out(); 350 assert(rgn->is_Region() || rgn->is_Call(), "must be a region or call uct"); 351 entry = entry->in(0)->in(0); 352 while (entry != NULL && entry->is_Proj() && entry->in(0)->is_If()) { 353 uncommon_proj = entry->in(0)->as_If()->proj_out(1 - entry->as_Proj()->_con); 354 if (uncommon_proj->unique_ctrl_out() != rgn) 355 break; 356 entry = entry->in(0)->in(0); 357 } 358 } 359 } 360 return entry; 361 } 362 363 //--------------------------find_predicate_insertion_point------------------- 364 // Find a good location to insert a predicate 365 ProjNode* PhaseIdealLoop::find_predicate_insertion_point(Node* start_c, Deoptimization::DeoptReason reason) { 366 if (start_c == NULL || !start_c->is_Proj()) 367 return NULL; 368 if (start_c->as_Proj()->is_uncommon_trap_if_pattern(reason)) { 369 return start_c->as_Proj(); 370 } 371 return NULL; 372 } 373 374 //--------------------------find_predicate------------------------------------ 375 // Find a predicate 376 Node* PhaseIdealLoop::find_predicate(Node* entry) { 377 Node* predicate = NULL; 378 if (LoopLimitCheck) { 379 predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check); 380 if (predicate != NULL) { // right pattern that can be used by loop predication 381 return entry; 382 } 383 } 384 if (UseLoopPredicate) { 385 predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate); 386 if (predicate != NULL) { // right pattern that can be used by loop predication 387 return entry; 388 } 389 } 390 return NULL; 391 } 392 393 //------------------------------Invariance----------------------------------- 394 // Helper class for loop_predication_impl to compute invariance on the fly and 395 // clone invariants. 396 class Invariance : public StackObj { 397 VectorSet _visited, _invariant; 398 Node_Stack _stack; 399 VectorSet _clone_visited; 400 Node_List _old_new; // map of old to new (clone) 401 IdealLoopTree* _lpt; 402 PhaseIdealLoop* _phase; 403 404 // Helper function to set up the invariance for invariance computation 405 // If n is a known invariant, set up directly. Otherwise, look up the 406 // the possibility to push n onto the stack for further processing. 407 void visit(Node* use, Node* n) { 408 if (_lpt->is_invariant(n)) { // known invariant 409 _invariant.set(n->_idx); 410 } else if (!n->is_CFG()) { 411 Node *n_ctrl = _phase->ctrl_or_self(n); 412 Node *u_ctrl = _phase->ctrl_or_self(use); // self if use is a CFG 413 if (_phase->is_dominator(n_ctrl, u_ctrl)) { 414 _stack.push(n, n->in(0) == NULL ? 1 : 0); 415 } 416 } 417 } 418 419 // Compute invariance for "the_node" and (possibly) all its inputs recursively 420 // on the fly 421 void compute_invariance(Node* n) { 422 assert(_visited.test(n->_idx), "must be"); 423 visit(n, n); 424 while (_stack.is_nonempty()) { 425 Node* n = _stack.node(); 426 uint idx = _stack.index(); 427 if (idx == n->req()) { // all inputs are processed 428 _stack.pop(); 429 // n is invariant if it's inputs are all invariant 430 bool all_inputs_invariant = true; 431 for (uint i = 0; i < n->req(); i++) { 432 Node* in = n->in(i); 433 if (in == NULL) continue; 434 assert(_visited.test(in->_idx), "must have visited input"); 435 if (!_invariant.test(in->_idx)) { // bad guy 436 all_inputs_invariant = false; 437 break; 438 } 439 } 440 if (all_inputs_invariant) { 441 _invariant.set(n->_idx); // I am a invariant too 442 } 443 } else { // process next input 444 _stack.set_index(idx + 1); 445 Node* m = n->in(idx); 446 if (m != NULL && !_visited.test_set(m->_idx)) { 447 visit(n, m); 448 } 449 } 450 } 451 } 452 453 // Helper function to set up _old_new map for clone_nodes. 454 // If n is a known invariant, set up directly ("clone" of n == n). 455 // Otherwise, push n onto the stack for real cloning. 456 void clone_visit(Node* n) { 457 assert(_invariant.test(n->_idx), "must be invariant"); 458 if (_lpt->is_invariant(n)) { // known invariant 459 _old_new.map(n->_idx, n); 460 } else { // to be cloned 461 assert(!n->is_CFG(), "should not see CFG here"); 462 _stack.push(n, n->in(0) == NULL ? 1 : 0); 463 } 464 } 465 466 // Clone "n" and (possibly) all its inputs recursively 467 void clone_nodes(Node* n, Node* ctrl) { 468 clone_visit(n); 469 while (_stack.is_nonempty()) { 470 Node* n = _stack.node(); 471 uint idx = _stack.index(); 472 if (idx == n->req()) { // all inputs processed, clone n! 473 _stack.pop(); 474 // clone invariant node 475 Node* n_cl = n->clone(); 476 _old_new.map(n->_idx, n_cl); 477 _phase->register_new_node(n_cl, ctrl); 478 for (uint i = 0; i < n->req(); i++) { 479 Node* in = n_cl->in(i); 480 if (in == NULL) continue; 481 n_cl->set_req(i, _old_new[in->_idx]); 482 } 483 } else { // process next input 484 _stack.set_index(idx + 1); 485 Node* m = n->in(idx); 486 if (m != NULL && !_clone_visited.test_set(m->_idx)) { 487 clone_visit(m); // visit the input 488 } 489 } 490 } 491 } 492 493 public: 494 Invariance(Arena* area, IdealLoopTree* lpt) : 495 _lpt(lpt), _phase(lpt->_phase), 496 _visited(area), _invariant(area), _stack(area, 10 /* guess */), 497 _clone_visited(area), _old_new(area) 498 {} 499 500 // Map old to n for invariance computation and clone 501 void map_ctrl(Node* old, Node* n) { 502 assert(old->is_CFG() && n->is_CFG(), "must be"); 503 _old_new.map(old->_idx, n); // "clone" of old is n 504 _invariant.set(old->_idx); // old is invariant 505 _clone_visited.set(old->_idx); 506 } 507 508 // Driver function to compute invariance 509 bool is_invariant(Node* n) { 510 if (!_visited.test_set(n->_idx)) 511 compute_invariance(n); 512 return (_invariant.test(n->_idx) != 0); 513 } 514 515 // Driver function to clone invariant 516 Node* clone(Node* n, Node* ctrl) { 517 assert(ctrl->is_CFG(), "must be"); 518 assert(_invariant.test(n->_idx), "must be an invariant"); 519 if (!_clone_visited.test(n->_idx)) 520 clone_nodes(n, ctrl); 521 return _old_new[n->_idx]; 522 } 523 }; 524 525 //------------------------------is_range_check_if ----------------------------------- 526 // Returns true if the predicate of iff is in "scale*iv + offset u< load_range(ptr)" format 527 // Note: this function is particularly designed for loop predication. We require load_range 528 // and offset to be loop invariant computed on the fly by "invar" 529 bool IdealLoopTree::is_range_check_if(IfNode *iff, PhaseIdealLoop *phase, Invariance& invar) const { 530 if (!is_loop_exit(iff)) { 531 return false; 532 } 533 if (!iff->in(1)->is_Bool()) { 534 return false; 535 } 536 const BoolNode *bol = iff->in(1)->as_Bool(); 537 if (bol->_test._test != BoolTest::lt) { 538 return false; 539 } 540 if (!bol->in(1)->is_Cmp()) { 541 return false; 542 } 543 const CmpNode *cmp = bol->in(1)->as_Cmp(); 544 if (cmp->Opcode() != Op_CmpU) { 545 return false; 546 } 547 Node* range = cmp->in(2); 548 if (range->Opcode() != Op_LoadRange) { 549 const TypeInt* tint = phase->_igvn.type(range)->isa_int(); 550 if (tint == NULL || tint->empty() || tint->_lo < 0) { 551 // Allow predication on positive values that aren't LoadRanges. 552 // This allows optimization of loops where the length of the 553 // array is a known value and doesn't need to be loaded back 554 // from the array. 555 return false; 556 } 557 } 558 if (!invar.is_invariant(range)) { 559 return false; 560 } 561 Node *iv = _head->as_CountedLoop()->phi(); 562 int scale = 0; 563 Node *offset = NULL; 564 if (!phase->is_scaled_iv_plus_offset(cmp->in(1), iv, &scale, &offset)) { 565 return false; 566 } 567 if (offset && !invar.is_invariant(offset)) { // offset must be invariant 568 return false; 569 } 570 return true; 571 } 572 573 //------------------------------rc_predicate----------------------------------- 574 // Create a range check predicate 575 // 576 // for (i = init; i < limit; i += stride) { 577 // a[scale*i+offset] 578 // } 579 // 580 // Compute max(scale*i + offset) for init <= i < limit and build the predicate 581 // as "max(scale*i + offset) u< a.length". 582 // 583 // There are two cases for max(scale*i + offset): 584 // (1) stride*scale > 0 585 // max(scale*i + offset) = scale*(limit-stride) + offset 586 // (2) stride*scale < 0 587 // max(scale*i + offset) = scale*init + offset 588 BoolNode* PhaseIdealLoop::rc_predicate(IdealLoopTree *loop, Node* ctrl, 589 int scale, Node* offset, 590 Node* init, Node* limit, Node* stride, 591 Node* range, bool upper) { 592 stringStream* predString = NULL; 593 if (TraceLoopPredicate) { 594 predString = new stringStream(); 595 predString->print("rc_predicate "); 596 } 597 598 Node* max_idx_expr = init; 599 int stride_con = stride->get_int(); 600 if ((stride_con > 0) == (scale > 0) == upper) { 601 if (LoopLimitCheck) { 602 // With LoopLimitCheck limit is not exact. 603 // Calculate exact limit here. 604 // Note, counted loop's test is '<' or '>'. 605 limit = exact_limit(loop); 606 max_idx_expr = new (C) SubINode(limit, stride); 607 register_new_node(max_idx_expr, ctrl); 608 if (TraceLoopPredicate) predString->print("(limit - stride) "); 609 } else { 610 max_idx_expr = new (C) SubINode(limit, stride); 611 register_new_node(max_idx_expr, ctrl); 612 if (TraceLoopPredicate) predString->print("(limit - stride) "); 613 } 614 } else { 615 if (TraceLoopPredicate) predString->print("init "); 616 } 617 618 if (scale != 1) { 619 ConNode* con_scale = _igvn.intcon(scale); 620 max_idx_expr = new (C) MulINode(max_idx_expr, con_scale); 621 register_new_node(max_idx_expr, ctrl); 622 if (TraceLoopPredicate) predString->print("* %d ", scale); 623 } 624 625 if (offset && (!offset->is_Con() || offset->get_int() != 0)){ 626 max_idx_expr = new (C) AddINode(max_idx_expr, offset); 627 register_new_node(max_idx_expr, ctrl); 628 if (TraceLoopPredicate) 629 if (offset->is_Con()) predString->print("+ %d ", offset->get_int()); 630 else predString->print("+ offset "); 631 } 632 633 CmpUNode* cmp = new (C) CmpUNode(max_idx_expr, range); 634 register_new_node(cmp, ctrl); 635 BoolNode* bol = new (C) BoolNode(cmp, BoolTest::lt); 636 register_new_node(bol, ctrl); 637 638 if (TraceLoopPredicate) { 639 predString->print_cr("<u range"); 640 tty->print(predString->as_string()); 641 } 642 return bol; 643 } 644 645 //------------------------------ loop_predication_impl-------------------------- 646 // Insert loop predicates for null checks and range checks 647 bool PhaseIdealLoop::loop_predication_impl(IdealLoopTree *loop) { 648 if (!UseLoopPredicate) return false; 649 650 if (!loop->_head->is_Loop()) { 651 // Could be a simple region when irreducible loops are present. 652 return false; 653 } 654 LoopNode* head = loop->_head->as_Loop(); 655 656 if (head->unique_ctrl_out()->Opcode() == Op_NeverBranch) { 657 // do nothing for infinite loops 658 return false; 659 } 660 661 CountedLoopNode *cl = NULL; 662 if (head->is_valid_counted_loop()) { 663 cl = head->as_CountedLoop(); 664 // do nothing for iteration-splitted loops 665 if (!cl->is_normal_loop()) return false; 666 // Avoid RCE if Counted loop's test is '!='. 667 BoolTest::mask bt = cl->loopexit()->test_trip(); 668 if (bt != BoolTest::lt && bt != BoolTest::gt) 669 cl = NULL; 670 } 671 672 Node* entry = head->in(LoopNode::EntryControl); 673 ProjNode *predicate_proj = NULL; 674 // Loop limit check predicate should be near the loop. 675 if (LoopLimitCheck) { 676 predicate_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check); 677 if (predicate_proj != NULL) 678 entry = predicate_proj->in(0)->in(0); 679 } 680 681 predicate_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate); 682 if (!predicate_proj) { 683 #ifndef PRODUCT 684 if (TraceLoopPredicate) { 685 tty->print("missing predicate:"); 686 loop->dump_head(); 687 head->dump(1); 688 } 689 #endif 690 return false; 691 } 692 ConNode* zero = _igvn.intcon(0); 693 set_ctrl(zero, C->root()); 694 695 ResourceArea *area = Thread::current()->resource_area(); 696 Invariance invar(area, loop); 697 698 // Create list of if-projs such that a newer proj dominates all older 699 // projs in the list, and they all dominate loop->tail() 700 Node_List if_proj_list(area); 701 Node *current_proj = loop->tail(); //start from tail 702 while (current_proj != head) { 703 if (loop == get_loop(current_proj) && // still in the loop ? 704 current_proj->is_Proj() && // is a projection ? 705 current_proj->in(0)->Opcode() == Op_If) { // is a if projection ? 706 if_proj_list.push(current_proj); 707 } 708 current_proj = idom(current_proj); 709 } 710 711 bool hoisted = false; // true if at least one proj is promoted 712 while (if_proj_list.size() > 0) { 713 // Following are changed to nonnull when a predicate can be hoisted 714 ProjNode* new_predicate_proj = NULL; 715 716 ProjNode* proj = if_proj_list.pop()->as_Proj(); 717 IfNode* iff = proj->in(0)->as_If(); 718 719 if (!proj->is_uncommon_trap_if_pattern(Deoptimization::Reason_none)) { 720 if (loop->is_loop_exit(iff)) { 721 // stop processing the remaining projs in the list because the execution of them 722 // depends on the condition of "iff" (iff->in(1)). 723 break; 724 } else { 725 // Both arms are inside the loop. There are two cases: 726 // (1) there is one backward branch. In this case, any remaining proj 727 // in the if_proj list post-dominates "iff". So, the condition of "iff" 728 // does not determine the execution the remining projs directly, and we 729 // can safely continue. 730 // (2) both arms are forwarded, i.e. a diamond shape. In this case, "proj" 731 // does not dominate loop->tail(), so it can not be in the if_proj list. 732 continue; 733 } 734 } 735 736 Node* test = iff->in(1); 737 if (!test->is_Bool()){ //Conv2B, ... 738 continue; 739 } 740 BoolNode* bol = test->as_Bool(); 741 if (invar.is_invariant(bol)) { 742 // Invariant test 743 new_predicate_proj = create_new_if_for_predicate(predicate_proj, NULL, 744 Deoptimization::Reason_predicate); 745 Node* ctrl = new_predicate_proj->in(0)->as_If()->in(0); 746 BoolNode* new_predicate_bol = invar.clone(bol, ctrl)->as_Bool(); 747 748 // Negate test if necessary 749 bool negated = false; 750 if (proj->_con != predicate_proj->_con) { 751 new_predicate_bol = new (C) BoolNode(new_predicate_bol->in(1), new_predicate_bol->_test.negate()); 752 register_new_node(new_predicate_bol, ctrl); 753 negated = true; 754 } 755 IfNode* new_predicate_iff = new_predicate_proj->in(0)->as_If(); 756 _igvn.hash_delete(new_predicate_iff); 757 new_predicate_iff->set_req(1, new_predicate_bol); 758 #ifndef PRODUCT 759 if (TraceLoopPredicate) { 760 tty->print("Predicate invariant if%s: %d ", negated ? " negated" : "", new_predicate_iff->_idx); 761 loop->dump_head(); 762 } else if (TraceLoopOpts) { 763 tty->print("Predicate IC "); 764 loop->dump_head(); 765 } 766 #endif 767 } else if ((cl != NULL) && (proj->_con == predicate_proj->_con) && 768 loop->is_range_check_if(iff, this, invar)) { 769 770 // Range check for counted loops 771 const Node* cmp = bol->in(1)->as_Cmp(); 772 Node* idx = cmp->in(1); 773 assert(!invar.is_invariant(idx), "index is variant"); 774 Node* rng = cmp->in(2); 775 assert(rng->Opcode() == Op_LoadRange || _igvn.type(rng)->is_int() >= 0, "must be"); 776 assert(invar.is_invariant(rng), "range must be invariant"); 777 int scale = 1; 778 Node* offset = zero; 779 bool ok = is_scaled_iv_plus_offset(idx, cl->phi(), &scale, &offset); 780 assert(ok, "must be index expression"); 781 782 Node* init = cl->init_trip(); 783 Node* limit = cl->limit(); 784 Node* stride = cl->stride(); 785 786 // Build if's for the upper and lower bound tests. The 787 // lower_bound test will dominate the upper bound test and all 788 // cloned or created nodes will use the lower bound test as 789 // their declared control. 790 ProjNode* lower_bound_proj = create_new_if_for_predicate(predicate_proj, NULL, Deoptimization::Reason_predicate); 791 ProjNode* upper_bound_proj = create_new_if_for_predicate(predicate_proj, NULL, Deoptimization::Reason_predicate); 792 assert(upper_bound_proj->in(0)->as_If()->in(0) == lower_bound_proj, "should dominate"); 793 Node *ctrl = lower_bound_proj->in(0)->as_If()->in(0); 794 795 // Perform cloning to keep Invariance state correct since the 796 // late schedule will place invariant things in the loop. 797 rng = invar.clone(rng, ctrl); 798 if (offset && offset != zero) { 799 assert(invar.is_invariant(offset), "offset must be loop invariant"); 800 offset = invar.clone(offset, ctrl); 801 } 802 803 // Test the lower bound 804 Node* lower_bound_bol = rc_predicate(loop, ctrl, scale, offset, init, limit, stride, rng, false); 805 IfNode* lower_bound_iff = lower_bound_proj->in(0)->as_If(); 806 _igvn.hash_delete(lower_bound_iff); 807 lower_bound_iff->set_req(1, lower_bound_bol); 808 if (TraceLoopPredicate) tty->print_cr("lower bound check if: %d", lower_bound_iff->_idx); 809 810 // Test the upper bound 811 Node* upper_bound_bol = rc_predicate(loop, lower_bound_proj, scale, offset, init, limit, stride, rng, true); 812 IfNode* upper_bound_iff = upper_bound_proj->in(0)->as_If(); 813 _igvn.hash_delete(upper_bound_iff); 814 upper_bound_iff->set_req(1, upper_bound_bol); 815 if (TraceLoopPredicate) tty->print_cr("upper bound check if: %d", lower_bound_iff->_idx); 816 817 // Fall through into rest of the clean up code which will move 818 // any dependent nodes onto the upper bound test. 819 new_predicate_proj = upper_bound_proj; 820 821 #ifndef PRODUCT 822 if (TraceLoopOpts && !TraceLoopPredicate) { 823 tty->print("Predicate RC "); 824 loop->dump_head(); 825 } 826 #endif 827 } else { 828 // Loop variant check (for example, range check in non-counted loop) 829 // with uncommon trap. 830 continue; 831 } 832 assert(new_predicate_proj != NULL, "sanity"); 833 // Success - attach condition (new_predicate_bol) to predicate if 834 invar.map_ctrl(proj, new_predicate_proj); // so that invariance test can be appropriate 835 836 // Eliminate the old If in the loop body 837 dominated_by( new_predicate_proj, iff, proj->_con != new_predicate_proj->_con ); 838 839 hoisted = true; 840 C->set_major_progress(); 841 } // end while 842 843 #ifndef PRODUCT 844 // report that the loop predication has been actually performed 845 // for this loop 846 if (TraceLoopPredicate && hoisted) { 847 tty->print("Loop Predication Performed:"); 848 loop->dump_head(); 849 } 850 #endif 851 852 return hoisted; 853 } 854 855 //------------------------------loop_predication-------------------------------- 856 // driver routine for loop predication optimization 857 bool IdealLoopTree::loop_predication( PhaseIdealLoop *phase) { 858 bool hoisted = false; 859 // Recursively promote predicates 860 if (_child) { 861 hoisted = _child->loop_predication( phase); 862 } 863 864 // self 865 if (!_irreducible && !tail()->is_top()) { 866 hoisted |= phase->loop_predication_impl(this); 867 } 868 869 if (_next) { //sibling 870 hoisted |= _next->loop_predication( phase); 871 } 872 873 return hoisted; 874 }