1 /* 2 * Copyright (c) 2011, 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 //-------------------------------is_uncommon_trap_proj---------------------------- 45 // Return true if proj is the form of "proj->[region->..]call_uct" 46 bool PhaseIdealLoop::is_uncommon_trap_proj(ProjNode* proj, Deoptimization::DeoptReason reason) { 47 int path_limit = 10; 48 assert(proj, "invalid argument"); 49 Node* out = proj; 50 for (int ct = 0; ct < path_limit; ct++) { 51 out = out->unique_ctrl_out(); 52 if (out == NULL) 53 return false; 54 if (out->is_CallStaticJava()) { 55 int req = out->as_CallStaticJava()->uncommon_trap_request(); 56 if (req != 0) { 57 Deoptimization::DeoptReason trap_reason = Deoptimization::trap_request_reason(req); 58 if (trap_reason == reason || reason == Deoptimization::Reason_none) { 59 return true; 60 } 61 } 62 return false; // don't do further after call 63 } 64 if (out->Opcode() != Op_Region) 65 return false; 66 } 67 return false; 68 } 69 70 //-------------------------------is_uncommon_trap_if_pattern------------------------- 71 // Return true for "if(test)-> proj -> ... 72 // | 73 // V 74 // other_proj->[region->..]call_uct" 75 // 76 // "must_reason_predicate" means the uct reason must be Reason_predicate 77 bool PhaseIdealLoop::is_uncommon_trap_if_pattern(ProjNode *proj, Deoptimization::DeoptReason reason) { 78 Node *in0 = proj->in(0); 79 if (!in0->is_If()) return false; 80 // Variation of a dead If node. 81 if (in0->outcnt() < 2) return false; 82 IfNode* iff = in0->as_If(); 83 84 // we need "If(Conv2B(Opaque1(...)))" pattern for reason_predicate 85 if (reason != Deoptimization::Reason_none) { 86 if (iff->in(1)->Opcode() != Op_Conv2B || 87 iff->in(1)->in(1)->Opcode() != Op_Opaque1) { 88 return false; 89 } 90 } 91 92 ProjNode* other_proj = iff->proj_out(1-proj->_con)->as_Proj(); 93 if (is_uncommon_trap_proj(other_proj, reason)) { 94 assert(reason == Deoptimization::Reason_none || 95 Compile::current()->is_predicate_opaq(iff->in(1)->in(1)), "should be on the list"); 96 return true; 97 } 98 return false; 99 } 100 101 //-------------------------------register_control------------------------- 102 void PhaseIdealLoop::register_control(Node* n, IdealLoopTree *loop, Node* pred) { 103 assert(n->is_CFG(), "must be control node"); 104 _igvn.register_new_node_with_optimizer(n); 105 loop->_body.push(n); 106 set_loop(n, loop); 107 // When called from beautify_loops() idom is not constructed yet. 108 if (_idom != NULL) { 109 set_idom(n, pred, dom_depth(pred)); 110 } 111 } 112 113 //------------------------------create_new_if_for_predicate------------------------ 114 // create a new if above the uct_if_pattern for the predicate to be promoted. 115 // 116 // before after 117 // ---------- ---------- 118 // ctrl ctrl 119 // | | 120 // | | 121 // v v 122 // iff new_iff 123 // / \ / \ 124 // / \ / \ 125 // v v v v 126 // uncommon_proj cont_proj if_uct if_cont 127 // \ | | | | 128 // \ | | | | 129 // v v v | v 130 // rgn loop | iff 131 // | | / \ 132 // | | / \ 133 // v | v v 134 // uncommon_trap | uncommon_proj cont_proj 135 // \ \ | | 136 // \ \ | | 137 // v v v v 138 // rgn loop 139 // | 140 // | 141 // v 142 // uncommon_trap 143 // 144 // 145 // We will create a region to guard the uct call if there is no one there. 146 // The true projecttion (if_cont) of the new_iff is returned. 147 // This code is also used to clone predicates to clonned loops. 148 ProjNode* PhaseIdealLoop::create_new_if_for_predicate(ProjNode* cont_proj, Node* new_entry, 149 Deoptimization::DeoptReason reason) { 150 assert(is_uncommon_trap_if_pattern(cont_proj, reason), "must be a uct if pattern!"); 151 IfNode* iff = cont_proj->in(0)->as_If(); 152 153 ProjNode *uncommon_proj = iff->proj_out(1 - cont_proj->_con); 154 Node *rgn = uncommon_proj->unique_ctrl_out(); 155 assert(rgn->is_Region() || rgn->is_Call(), "must be a region or call uct"); 156 157 uint proj_index = 1; // region's edge corresponding to uncommon_proj 158 if (!rgn->is_Region()) { // create a region to guard the call 159 assert(rgn->is_Call(), "must be call uct"); 160 CallNode* call = rgn->as_Call(); 161 IdealLoopTree* loop = get_loop(call); 162 rgn = new (C, 1) RegionNode(1); 163 rgn->add_req(uncommon_proj); 164 register_control(rgn, loop, uncommon_proj); 165 _igvn.hash_delete(call); 166 call->set_req(0, rgn); 167 // When called from beautify_loops() idom is not constructed yet. 168 if (_idom != NULL) { 169 set_idom(call, rgn, dom_depth(rgn)); 170 } 171 } else { 172 // Find region's edge corresponding to uncommon_proj 173 for (; proj_index < rgn->req(); proj_index++) 174 if (rgn->in(proj_index) == uncommon_proj) break; 175 assert(proj_index < rgn->req(), "sanity"); 176 } 177 178 Node* entry = iff->in(0); 179 if (new_entry != NULL) { 180 // Clonning the predicate to new location. 181 entry = new_entry; 182 } 183 // Create new_iff 184 IdealLoopTree* lp = get_loop(entry); 185 IfNode *new_iff = iff->clone()->as_If(); 186 new_iff->set_req(0, entry); 187 register_control(new_iff, lp, entry); 188 Node *if_cont = new (C, 1) IfTrueNode(new_iff); 189 Node *if_uct = new (C, 1) IfFalseNode(new_iff); 190 if (cont_proj->is_IfFalse()) { 191 // Swap 192 Node* tmp = if_uct; if_uct = if_cont; if_cont = tmp; 193 } 194 register_control(if_cont, lp, new_iff); 195 register_control(if_uct, get_loop(rgn), new_iff); 196 197 // if_uct to rgn 198 _igvn.hash_delete(rgn); 199 rgn->add_req(if_uct); 200 // When called from beautify_loops() idom is not constructed yet. 201 if (_idom != NULL) { 202 Node* ridom = idom(rgn); 203 Node* nrdom = dom_lca(ridom, new_iff); 204 set_idom(rgn, nrdom, dom_depth(rgn)); 205 } 206 207 // If rgn has phis add new edges which has the same 208 // value as on original uncommon_proj pass. 209 assert(rgn->in(rgn->req() -1) == if_uct, "new edge should be last"); 210 bool has_phi = false; 211 for (DUIterator_Fast imax, i = rgn->fast_outs(imax); i < imax; i++) { 212 Node* use = rgn->fast_out(i); 213 if (use->is_Phi() && use->outcnt() > 0) { 214 assert(use->in(0) == rgn, ""); 215 _igvn.hash_delete(use); 216 use->add_req(use->in(proj_index)); 217 _igvn._worklist.push(use); 218 has_phi = true; 219 } 220 } 221 assert(!has_phi || rgn->req() > 3, "no phis when region is created"); 222 223 if (new_entry == NULL) { 224 // Attach if_cont to iff 225 _igvn.hash_delete(iff); 226 iff->set_req(0, if_cont); 227 if (_idom != NULL) { 228 set_idom(iff, if_cont, dom_depth(iff)); 229 } 230 } 231 return if_cont->as_Proj(); 232 } 233 234 //------------------------------create_new_if_for_predicate------------------------ 235 // Create a new if below new_entry for the predicate to be cloned (IGVN optimization) 236 ProjNode* PhaseIterGVN::create_new_if_for_predicate(ProjNode* cont_proj, Node* new_entry, 237 Deoptimization::DeoptReason reason) { 238 assert(new_entry != 0, "only used for clone predicate"); 239 assert(PhaseIdealLoop::is_uncommon_trap_if_pattern(cont_proj, reason), "must be a uct if pattern!"); 240 IfNode* iff = cont_proj->in(0)->as_If(); 241 242 ProjNode *uncommon_proj = iff->proj_out(1 - cont_proj->_con); 243 Node *rgn = uncommon_proj->unique_ctrl_out(); 244 assert(rgn->is_Region() || rgn->is_Call(), "must be a region or call uct"); 245 246 uint proj_index = 1; // region's edge corresponding to uncommon_proj 247 if (!rgn->is_Region()) { // create a region to guard the call 248 assert(rgn->is_Call(), "must be call uct"); 249 CallNode* call = rgn->as_Call(); 250 rgn = new (C, 1) RegionNode(1); 251 register_new_node_with_optimizer(rgn); 252 rgn->add_req(uncommon_proj); 253 hash_delete(call); 254 call->set_req(0, rgn); 255 } else { 256 // Find region's edge corresponding to uncommon_proj 257 for (; proj_index < rgn->req(); proj_index++) 258 if (rgn->in(proj_index) == uncommon_proj) break; 259 assert(proj_index < rgn->req(), "sanity"); 260 } 261 262 // Create new_iff in new location. 263 IfNode *new_iff = iff->clone()->as_If(); 264 new_iff->set_req(0, new_entry); 265 266 register_new_node_with_optimizer(new_iff); 267 Node *if_cont = new (C, 1) IfTrueNode(new_iff); 268 Node *if_uct = new (C, 1) IfFalseNode(new_iff); 269 if (cont_proj->is_IfFalse()) { 270 // Swap 271 Node* tmp = if_uct; if_uct = if_cont; if_cont = tmp; 272 } 273 register_new_node_with_optimizer(if_cont); 274 register_new_node_with_optimizer(if_uct); 275 276 // if_uct to rgn 277 hash_delete(rgn); 278 rgn->add_req(if_uct); 279 280 // If rgn has phis add corresponding new edges which has the same 281 // value as on original uncommon_proj pass. 282 assert(rgn->in(rgn->req() -1) == if_uct, "new edge should be last"); 283 bool has_phi = false; 284 for (DUIterator_Fast imax, i = rgn->fast_outs(imax); i < imax; i++) { 285 Node* use = rgn->fast_out(i); 286 if (use->is_Phi() && use->outcnt() > 0) { 287 hash_delete(use); 288 use->add_req(use->in(proj_index)); 289 _worklist.push(use); 290 has_phi = true; 291 } 292 } 293 assert(!has_phi || rgn->req() > 3, "no phis when region is created"); 294 295 return if_cont->as_Proj(); 296 } 297 298 //--------------------------clone_predicate----------------------- 299 ProjNode* PhaseIdealLoop::clone_predicate(ProjNode* predicate_proj, Node* new_entry, 300 Deoptimization::DeoptReason reason, 301 PhaseIdealLoop* loop_phase, 302 PhaseIterGVN* igvn) { 303 ProjNode* new_predicate_proj; 304 if (loop_phase != NULL) { 305 new_predicate_proj = loop_phase->create_new_if_for_predicate(predicate_proj, new_entry, reason); 306 } else { 307 new_predicate_proj = igvn->create_new_if_for_predicate(predicate_proj, new_entry, reason); 308 } 309 IfNode* iff = new_predicate_proj->in(0)->as_If(); 310 Node* ctrl = iff->in(0); 311 312 // Match original condition since predicate's projections could be swapped. 313 assert(predicate_proj->in(0)->in(1)->in(1)->Opcode()==Op_Opaque1, "must be"); 314 Node* opq = new (igvn->C, 2) Opaque1Node(igvn->C, predicate_proj->in(0)->in(1)->in(1)->in(1)); 315 igvn->C->add_predicate_opaq(opq); 316 317 Node* bol = new (igvn->C, 2) Conv2BNode(opq); 318 if (loop_phase != NULL) { 319 loop_phase->register_new_node(opq, ctrl); 320 loop_phase->register_new_node(bol, ctrl); 321 } else { 322 igvn->register_new_node_with_optimizer(opq); 323 igvn->register_new_node_with_optimizer(bol); 324 } 325 igvn->hash_delete(iff); 326 iff->set_req(1, bol); 327 return new_predicate_proj; 328 } 329 330 331 //--------------------------clone_loop_predicates----------------------- 332 // Interface from IGVN 333 Node* PhaseIterGVN::clone_loop_predicates(Node* old_entry, Node* new_entry, bool clone_limit_check) { 334 return PhaseIdealLoop::clone_loop_predicates(old_entry, new_entry, clone_limit_check, NULL, this); 335 } 336 337 // Interface from PhaseIdealLoop 338 Node* PhaseIdealLoop::clone_loop_predicates(Node* old_entry, Node* new_entry, bool clone_limit_check) { 339 return clone_loop_predicates(old_entry, new_entry, clone_limit_check, this, &this->_igvn); 340 } 341 342 // Clone loop predicates to cloned loops (peeled, unswitched, split_if). 343 Node* PhaseIdealLoop::clone_loop_predicates(Node* old_entry, Node* new_entry, 344 bool clone_limit_check, 345 PhaseIdealLoop* loop_phase, 346 PhaseIterGVN* igvn) { 347 #ifdef ASSERT 348 if (new_entry == NULL || !(new_entry->is_Proj() || new_entry->is_Region() || new_entry->is_SafePoint())) { 349 if (new_entry != NULL) 350 new_entry->dump(); 351 assert(false, "not IfTrue, IfFalse, Region or SafePoint"); 352 } 353 #endif 354 // Search original predicates 355 Node* entry = old_entry; 356 ProjNode* limit_check_proj = NULL; 357 if (LoopLimitCheck) { 358 limit_check_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check); 359 if (limit_check_proj != NULL) { 360 entry = entry->in(0)->in(0); 361 } 362 } 363 if (UseLoopPredicate) { 364 ProjNode* predicate_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate); 365 if (predicate_proj != NULL) { // right pattern that can be used by loop predication 366 // clone predicate 367 new_entry = clone_predicate(predicate_proj, new_entry, 368 Deoptimization::Reason_predicate, 369 loop_phase, igvn); 370 assert(new_entry != NULL && new_entry->is_Proj(), "IfTrue or IfFalse after clone predicate"); 371 if (TraceLoopPredicate) { 372 tty->print("Loop Predicate cloned: "); 373 debug_only( new_entry->in(0)->dump(); ) 374 } 375 } 376 } 377 if (limit_check_proj != NULL && clone_limit_check) { 378 // Clone loop limit check last to insert it before loop. 379 // Don't clone a limit check which was already finalized 380 // for this counted loop (only one limit check is needed). 381 new_entry = clone_predicate(limit_check_proj, new_entry, 382 Deoptimization::Reason_loop_limit_check, 383 loop_phase, igvn); 384 assert(new_entry != NULL && new_entry->is_Proj(), "IfTrue or IfFalse after clone limit check"); 385 if (TraceLoopLimitCheck) { 386 tty->print("Loop Limit Check cloned: "); 387 debug_only( new_entry->in(0)->dump(); ) 388 } 389 } 390 return new_entry; 391 } 392 393 //--------------------------skip_loop_predicates------------------------------ 394 // Skip related predicates. 395 Node* PhaseIdealLoop::skip_loop_predicates(Node* entry) { 396 Node* predicate = NULL; 397 if (LoopLimitCheck) { 398 predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check); 399 if (predicate != NULL) { 400 entry = entry->in(0)->in(0); 401 } 402 } 403 if (UseLoopPredicate) { 404 predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate); 405 if (predicate != NULL) { // right pattern that can be used by loop predication 406 IfNode* iff = entry->in(0)->as_If(); 407 ProjNode* uncommon_proj = iff->proj_out(1 - entry->as_Proj()->_con); 408 Node* rgn = uncommon_proj->unique_ctrl_out(); 409 assert(rgn->is_Region() || rgn->is_Call(), "must be a region or call uct"); 410 entry = entry->in(0)->in(0); 411 while (entry != NULL && entry->is_Proj() && entry->in(0)->is_If()) { 412 uncommon_proj = entry->in(0)->as_If()->proj_out(1 - entry->as_Proj()->_con); 413 if (uncommon_proj->unique_ctrl_out() != rgn) 414 break; 415 entry = entry->in(0)->in(0); 416 } 417 } 418 } 419 return entry; 420 } 421 422 //--------------------------find_predicate_insertion_point------------------- 423 // Find a good location to insert a predicate 424 ProjNode* PhaseIdealLoop::find_predicate_insertion_point(Node* start_c, Deoptimization::DeoptReason reason) { 425 if (start_c == NULL || !start_c->is_Proj()) 426 return NULL; 427 if (is_uncommon_trap_if_pattern(start_c->as_Proj(), reason)) { 428 return start_c->as_Proj(); 429 } 430 return NULL; 431 } 432 433 //--------------------------find_predicate------------------------------------ 434 // Find a predicate 435 Node* PhaseIdealLoop::find_predicate(Node* entry) { 436 Node* predicate = NULL; 437 if (LoopLimitCheck) { 438 predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check); 439 if (predicate != NULL) { // right pattern that can be used by loop predication 440 return entry; 441 } 442 } 443 if (UseLoopPredicate) { 444 predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate); 445 if (predicate != NULL) { // right pattern that can be used by loop predication 446 return entry; 447 } 448 } 449 return NULL; 450 } 451 452 //------------------------------Invariance----------------------------------- 453 // Helper class for loop_predication_impl to compute invariance on the fly and 454 // clone invariants. 455 class Invariance : public StackObj { 456 VectorSet _visited, _invariant; 457 Node_Stack _stack; 458 VectorSet _clone_visited; 459 Node_List _old_new; // map of old to new (clone) 460 IdealLoopTree* _lpt; 461 PhaseIdealLoop* _phase; 462 463 // Helper function to set up the invariance for invariance computation 464 // If n is a known invariant, set up directly. Otherwise, look up the 465 // the possibility to push n onto the stack for further processing. 466 void visit(Node* use, Node* n) { 467 if (_lpt->is_invariant(n)) { // known invariant 468 _invariant.set(n->_idx); 469 } else if (!n->is_CFG()) { 470 Node *n_ctrl = _phase->ctrl_or_self(n); 471 Node *u_ctrl = _phase->ctrl_or_self(use); // self if use is a CFG 472 if (_phase->is_dominator(n_ctrl, u_ctrl)) { 473 _stack.push(n, n->in(0) == NULL ? 1 : 0); 474 } 475 } 476 } 477 478 // Compute invariance for "the_node" and (possibly) all its inputs recursively 479 // on the fly 480 void compute_invariance(Node* n) { 481 assert(_visited.test(n->_idx), "must be"); 482 visit(n, n); 483 while (_stack.is_nonempty()) { 484 Node* n = _stack.node(); 485 uint idx = _stack.index(); 486 if (idx == n->req()) { // all inputs are processed 487 _stack.pop(); 488 // n is invariant if it's inputs are all invariant 489 bool all_inputs_invariant = true; 490 for (uint i = 0; i < n->req(); i++) { 491 Node* in = n->in(i); 492 if (in == NULL) continue; 493 assert(_visited.test(in->_idx), "must have visited input"); 494 if (!_invariant.test(in->_idx)) { // bad guy 495 all_inputs_invariant = false; 496 break; 497 } 498 } 499 if (all_inputs_invariant) { 500 _invariant.set(n->_idx); // I am a invariant too 501 } 502 } else { // process next input 503 _stack.set_index(idx + 1); 504 Node* m = n->in(idx); 505 if (m != NULL && !_visited.test_set(m->_idx)) { 506 visit(n, m); 507 } 508 } 509 } 510 } 511 512 // Helper function to set up _old_new map for clone_nodes. 513 // If n is a known invariant, set up directly ("clone" of n == n). 514 // Otherwise, push n onto the stack for real cloning. 515 void clone_visit(Node* n) { 516 assert(_invariant.test(n->_idx), "must be invariant"); 517 if (_lpt->is_invariant(n)) { // known invariant 518 _old_new.map(n->_idx, n); 519 } else { // to be cloned 520 assert(!n->is_CFG(), "should not see CFG here"); 521 _stack.push(n, n->in(0) == NULL ? 1 : 0); 522 } 523 } 524 525 // Clone "n" and (possibly) all its inputs recursively 526 void clone_nodes(Node* n, Node* ctrl) { 527 clone_visit(n); 528 while (_stack.is_nonempty()) { 529 Node* n = _stack.node(); 530 uint idx = _stack.index(); 531 if (idx == n->req()) { // all inputs processed, clone n! 532 _stack.pop(); 533 // clone invariant node 534 Node* n_cl = n->clone(); 535 _old_new.map(n->_idx, n_cl); 536 _phase->register_new_node(n_cl, ctrl); 537 for (uint i = 0; i < n->req(); i++) { 538 Node* in = n_cl->in(i); 539 if (in == NULL) continue; 540 n_cl->set_req(i, _old_new[in->_idx]); 541 } 542 } else { // process next input 543 _stack.set_index(idx + 1); 544 Node* m = n->in(idx); 545 if (m != NULL && !_clone_visited.test_set(m->_idx)) { 546 clone_visit(m); // visit the input 547 } 548 } 549 } 550 } 551 552 public: 553 Invariance(Arena* area, IdealLoopTree* lpt) : 554 _lpt(lpt), _phase(lpt->_phase), 555 _visited(area), _invariant(area), _stack(area, 10 /* guess */), 556 _clone_visited(area), _old_new(area) 557 {} 558 559 // Map old to n for invariance computation and clone 560 void map_ctrl(Node* old, Node* n) { 561 assert(old->is_CFG() && n->is_CFG(), "must be"); 562 _old_new.map(old->_idx, n); // "clone" of old is n 563 _invariant.set(old->_idx); // old is invariant 564 _clone_visited.set(old->_idx); 565 } 566 567 // Driver function to compute invariance 568 bool is_invariant(Node* n) { 569 if (!_visited.test_set(n->_idx)) 570 compute_invariance(n); 571 return (_invariant.test(n->_idx) != 0); 572 } 573 574 // Driver function to clone invariant 575 Node* clone(Node* n, Node* ctrl) { 576 assert(ctrl->is_CFG(), "must be"); 577 assert(_invariant.test(n->_idx), "must be an invariant"); 578 if (!_clone_visited.test(n->_idx)) 579 clone_nodes(n, ctrl); 580 return _old_new[n->_idx]; 581 } 582 }; 583 584 //------------------------------is_range_check_if ----------------------------------- 585 // Returns true if the predicate of iff is in "scale*iv + offset u< load_range(ptr)" format 586 // Note: this function is particularly designed for loop predication. We require load_range 587 // and offset to be loop invariant computed on the fly by "invar" 588 bool IdealLoopTree::is_range_check_if(IfNode *iff, PhaseIdealLoop *phase, Invariance& invar) const { 589 if (!is_loop_exit(iff)) { 590 return false; 591 } 592 if (!iff->in(1)->is_Bool()) { 593 return false; 594 } 595 const BoolNode *bol = iff->in(1)->as_Bool(); 596 if (bol->_test._test != BoolTest::lt) { 597 return false; 598 } 599 if (!bol->in(1)->is_Cmp()) { 600 return false; 601 } 602 const CmpNode *cmp = bol->in(1)->as_Cmp(); 603 if (cmp->Opcode() != Op_CmpU) { 604 return false; 605 } 606 Node* range = cmp->in(2); 607 if (range->Opcode() != Op_LoadRange) { 608 const TypeInt* tint = phase->_igvn.type(range)->isa_int(); 609 if (tint == NULL || tint->empty() || tint->_lo < 0) { 610 // Allow predication on positive values that aren't LoadRanges. 611 // This allows optimization of loops where the length of the 612 // array is a known value and doesn't need to be loaded back 613 // from the array. 614 return false; 615 } 616 } 617 if (!invar.is_invariant(range)) { 618 return false; 619 } 620 Node *iv = _head->as_CountedLoop()->phi(); 621 int scale = 0; 622 Node *offset = NULL; 623 if (!phase->is_scaled_iv_plus_offset(cmp->in(1), iv, &scale, &offset)) { 624 return false; 625 } 626 if (offset && !invar.is_invariant(offset)) { // offset must be invariant 627 return false; 628 } 629 return true; 630 } 631 632 //------------------------------rc_predicate----------------------------------- 633 // Create a range check predicate 634 // 635 // for (i = init; i < limit; i += stride) { 636 // a[scale*i+offset] 637 // } 638 // 639 // Compute max(scale*i + offset) for init <= i < limit and build the predicate 640 // as "max(scale*i + offset) u< a.length". 641 // 642 // There are two cases for max(scale*i + offset): 643 // (1) stride*scale > 0 644 // max(scale*i + offset) = scale*(limit-stride) + offset 645 // (2) stride*scale < 0 646 // max(scale*i + offset) = scale*init + offset 647 BoolNode* PhaseIdealLoop::rc_predicate(IdealLoopTree *loop, Node* ctrl, 648 int scale, Node* offset, 649 Node* init, Node* limit, Node* stride, 650 Node* range, bool upper) { 651 stringStream* predString = NULL; 652 if (TraceLoopPredicate) { 653 predString = new stringStream(); 654 predString->print("rc_predicate "); 655 } 656 657 Node* max_idx_expr = init; 658 int stride_con = stride->get_int(); 659 if ((stride_con > 0) == (scale > 0) == upper) { 660 if (LoopLimitCheck) { 661 // With LoopLimitCheck limit is not exact. 662 // Calculate exact limit here. 663 // Note, counted loop's test is '<' or '>'. 664 limit = exact_limit(loop); 665 max_idx_expr = new (C, 3) SubINode(limit, stride); 666 register_new_node(max_idx_expr, ctrl); 667 if (TraceLoopPredicate) predString->print("(limit - stride) "); 668 } else { 669 max_idx_expr = new (C, 3) SubINode(limit, stride); 670 register_new_node(max_idx_expr, ctrl); 671 if (TraceLoopPredicate) predString->print("(limit - stride) "); 672 } 673 } else { 674 if (TraceLoopPredicate) predString->print("init "); 675 } 676 677 if (scale != 1) { 678 ConNode* con_scale = _igvn.intcon(scale); 679 max_idx_expr = new (C, 3) MulINode(max_idx_expr, con_scale); 680 register_new_node(max_idx_expr, ctrl); 681 if (TraceLoopPredicate) predString->print("* %d ", scale); 682 } 683 684 if (offset && (!offset->is_Con() || offset->get_int() != 0)){ 685 max_idx_expr = new (C, 3) AddINode(max_idx_expr, offset); 686 register_new_node(max_idx_expr, ctrl); 687 if (TraceLoopPredicate) 688 if (offset->is_Con()) predString->print("+ %d ", offset->get_int()); 689 else predString->print("+ offset "); 690 } 691 692 CmpUNode* cmp = new (C, 3) CmpUNode(max_idx_expr, range); 693 register_new_node(cmp, ctrl); 694 BoolNode* bol = new (C, 2) BoolNode(cmp, BoolTest::lt); 695 register_new_node(bol, ctrl); 696 697 if (TraceLoopPredicate) { 698 predString->print_cr("<u range"); 699 tty->print(predString->as_string()); 700 } 701 return bol; 702 } 703 704 //------------------------------ loop_predication_impl-------------------------- 705 // Insert loop predicates for null checks and range checks 706 bool PhaseIdealLoop::loop_predication_impl(IdealLoopTree *loop) { 707 if (!UseLoopPredicate) return false; 708 709 if (!loop->_head->is_Loop()) { 710 // Could be a simple region when irreducible loops are present. 711 return false; 712 } 713 LoopNode* head = loop->_head->as_Loop(); 714 715 if (head->unique_ctrl_out()->Opcode() == Op_NeverBranch) { 716 // do nothing for infinite loops 717 return false; 718 } 719 720 CountedLoopNode *cl = NULL; 721 if (head->is_CountedLoop()) { 722 cl = head->as_CountedLoop(); 723 // do nothing for iteration-splitted loops 724 if (!cl->is_normal_loop()) return false; 725 // Avoid RCE if Counted loop's test is '!='. 726 BoolTest::mask bt = cl->loopexit()->test_trip(); 727 if (bt != BoolTest::lt && bt != BoolTest::gt) 728 cl = NULL; 729 } 730 731 Node* entry = head->in(LoopNode::EntryControl); 732 ProjNode *predicate_proj = NULL; 733 // Loop limit check predicate should be near the loop. 734 if (LoopLimitCheck) { 735 predicate_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check); 736 if (predicate_proj != NULL) 737 entry = predicate_proj->in(0)->in(0); 738 } 739 740 predicate_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate); 741 if (!predicate_proj) { 742 #ifndef PRODUCT 743 if (TraceLoopPredicate) { 744 tty->print("missing predicate:"); 745 loop->dump_head(); 746 head->dump(1); 747 } 748 #endif 749 return false; 750 } 751 ConNode* zero = _igvn.intcon(0); 752 set_ctrl(zero, C->root()); 753 754 ResourceArea *area = Thread::current()->resource_area(); 755 Invariance invar(area, loop); 756 757 // Create list of if-projs such that a newer proj dominates all older 758 // projs in the list, and they all dominate loop->tail() 759 Node_List if_proj_list(area); 760 Node *current_proj = loop->tail(); //start from tail 761 while (current_proj != head) { 762 if (loop == get_loop(current_proj) && // still in the loop ? 763 current_proj->is_Proj() && // is a projection ? 764 current_proj->in(0)->Opcode() == Op_If) { // is a if projection ? 765 if_proj_list.push(current_proj); 766 } 767 current_proj = idom(current_proj); 768 } 769 770 bool hoisted = false; // true if at least one proj is promoted 771 while (if_proj_list.size() > 0) { 772 // Following are changed to nonnull when a predicate can be hoisted 773 ProjNode* new_predicate_proj = NULL; 774 775 ProjNode* proj = if_proj_list.pop()->as_Proj(); 776 IfNode* iff = proj->in(0)->as_If(); 777 778 if (!is_uncommon_trap_if_pattern(proj, Deoptimization::Reason_none)) { 779 if (loop->is_loop_exit(iff)) { 780 // stop processing the remaining projs in the list because the execution of them 781 // depends on the condition of "iff" (iff->in(1)). 782 break; 783 } else { 784 // Both arms are inside the loop. There are two cases: 785 // (1) there is one backward branch. In this case, any remaining proj 786 // in the if_proj list post-dominates "iff". So, the condition of "iff" 787 // does not determine the execution the remining projs directly, and we 788 // can safely continue. 789 // (2) both arms are forwarded, i.e. a diamond shape. In this case, "proj" 790 // does not dominate loop->tail(), so it can not be in the if_proj list. 791 continue; 792 } 793 } 794 795 Node* test = iff->in(1); 796 if (!test->is_Bool()){ //Conv2B, ... 797 continue; 798 } 799 BoolNode* bol = test->as_Bool(); 800 if (invar.is_invariant(bol)) { 801 // Invariant test 802 new_predicate_proj = create_new_if_for_predicate(predicate_proj, NULL, 803 Deoptimization::Reason_predicate); 804 Node* ctrl = new_predicate_proj->in(0)->as_If()->in(0); 805 BoolNode* new_predicate_bol = invar.clone(bol, ctrl)->as_Bool(); 806 807 // Negate test if necessary 808 bool negated = false; 809 if (proj->_con != predicate_proj->_con) { 810 new_predicate_bol = new (C, 2) BoolNode(new_predicate_bol->in(1), new_predicate_bol->_test.negate()); 811 register_new_node(new_predicate_bol, ctrl); 812 negated = true; 813 } 814 IfNode* new_predicate_iff = new_predicate_proj->in(0)->as_If(); 815 _igvn.hash_delete(new_predicate_iff); 816 new_predicate_iff->set_req(1, new_predicate_bol); 817 #ifndef PRODUCT 818 if (TraceLoopPredicate) { 819 tty->print("Predicate invariant if%s: %d ", negated ? " negated" : "", new_predicate_iff->_idx); 820 loop->dump_head(); 821 } else if (TraceLoopOpts) { 822 tty->print("Predicate IC "); 823 loop->dump_head(); 824 } 825 #endif 826 } else if (cl != NULL && loop->is_range_check_if(iff, this, invar)) { 827 assert(proj->_con == predicate_proj->_con, "must match"); 828 829 // Range check for counted loops 830 const Node* cmp = bol->in(1)->as_Cmp(); 831 Node* idx = cmp->in(1); 832 assert(!invar.is_invariant(idx), "index is variant"); 833 Node* rng = cmp->in(2); 834 assert(rng->Opcode() == Op_LoadRange || _igvn.type(rng)->is_int() >= 0, "must be"); 835 assert(invar.is_invariant(rng), "range must be invariant"); 836 int scale = 1; 837 Node* offset = zero; 838 bool ok = is_scaled_iv_plus_offset(idx, cl->phi(), &scale, &offset); 839 assert(ok, "must be index expression"); 840 841 Node* init = cl->init_trip(); 842 Node* limit = cl->limit(); 843 Node* stride = cl->stride(); 844 845 // Build if's for the upper and lower bound tests. The 846 // lower_bound test will dominate the upper bound test and all 847 // cloned or created nodes will use the lower bound test as 848 // their declared control. 849 ProjNode* lower_bound_proj = create_new_if_for_predicate(predicate_proj, NULL, Deoptimization::Reason_predicate); 850 ProjNode* upper_bound_proj = create_new_if_for_predicate(predicate_proj, NULL, Deoptimization::Reason_predicate); 851 assert(upper_bound_proj->in(0)->as_If()->in(0) == lower_bound_proj, "should dominate"); 852 Node *ctrl = lower_bound_proj->in(0)->as_If()->in(0); 853 854 // Perform cloning to keep Invariance state correct since the 855 // late schedule will place invariant things in the loop. 856 rng = invar.clone(rng, ctrl); 857 if (offset && offset != zero) { 858 assert(invar.is_invariant(offset), "offset must be loop invariant"); 859 offset = invar.clone(offset, ctrl); 860 } 861 862 // Test the lower bound 863 Node* lower_bound_bol = rc_predicate(loop, ctrl, scale, offset, init, limit, stride, rng, false); 864 IfNode* lower_bound_iff = lower_bound_proj->in(0)->as_If(); 865 _igvn.hash_delete(lower_bound_iff); 866 lower_bound_iff->set_req(1, lower_bound_bol); 867 if (TraceLoopPredicate) tty->print_cr("lower bound check if: %d", lower_bound_iff->_idx); 868 869 // Test the upper bound 870 Node* upper_bound_bol = rc_predicate(loop, lower_bound_proj, scale, offset, init, limit, stride, rng, true); 871 IfNode* upper_bound_iff = upper_bound_proj->in(0)->as_If(); 872 _igvn.hash_delete(upper_bound_iff); 873 upper_bound_iff->set_req(1, upper_bound_bol); 874 if (TraceLoopPredicate) tty->print_cr("upper bound check if: %d", lower_bound_iff->_idx); 875 876 // Fall through into rest of the clean up code which will move 877 // any dependent nodes onto the upper bound test. 878 new_predicate_proj = upper_bound_proj; 879 880 #ifndef PRODUCT 881 if (TraceLoopOpts && !TraceLoopPredicate) { 882 tty->print("Predicate RC "); 883 loop->dump_head(); 884 } 885 #endif 886 } else { 887 // Loop variant check (for example, range check in non-counted loop) 888 // with uncommon trap. 889 continue; 890 } 891 assert(new_predicate_proj != NULL, "sanity"); 892 // Success - attach condition (new_predicate_bol) to predicate if 893 invar.map_ctrl(proj, new_predicate_proj); // so that invariance test can be appropriate 894 895 // Eliminate the old If in the loop body 896 dominated_by( new_predicate_proj, iff, proj->_con != new_predicate_proj->_con ); 897 898 hoisted = true; 899 C->set_major_progress(); 900 } // end while 901 902 #ifndef PRODUCT 903 // report that the loop predication has been actually performed 904 // for this loop 905 if (TraceLoopPredicate && hoisted) { 906 tty->print("Loop Predication Performed:"); 907 loop->dump_head(); 908 } 909 #endif 910 911 return hoisted; 912 } 913 914 //------------------------------loop_predication-------------------------------- 915 // driver routine for loop predication optimization 916 bool IdealLoopTree::loop_predication( PhaseIdealLoop *phase) { 917 bool hoisted = false; 918 // Recursively promote predicates 919 if (_child) { 920 hoisted = _child->loop_predication( phase); 921 } 922 923 // self 924 if (!_irreducible && !tail()->is_top()) { 925 hoisted |= phase->loop_predication_impl(this); 926 } 927 928 if (_next) { //sibling 929 hoisted |= _next->loop_predication( phase); 930 } 931 932 return hoisted; 933 }