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 //--------------------------move_predicate----------------------- 331 // Cut predicate from old place and move it to new. 332 ProjNode* PhaseIdealLoop::move_predicate(ProjNode* predicate_proj, Node* new_entry, 333 Deoptimization::DeoptReason reason, 334 PhaseIdealLoop* loop_phase, 335 PhaseIterGVN* igvn) { 336 assert(new_entry != NULL, "must be"); 337 assert(predicate_proj->in(0)->in(1)->in(1)->Opcode()==Op_Opaque1, "must be"); 338 IfNode* iff = predicate_proj->in(0)->as_If(); 339 Node* old_entry = iff->in(0); 340 341 // Cut predicate from old place. 342 Node* old = predicate_proj; 343 igvn->_worklist.push(old); 344 for (DUIterator_Last imin, i = old->last_outs(imin); i >= imin;) { 345 Node* use = old->last_out(i); // for each use... 346 igvn->hash_delete(use); 347 igvn->_worklist.push(use); 348 // Update use-def info 349 uint uses_found = 0; 350 for (uint j = 0; j < use->req(); j++) { 351 if (use->in(j) == old) { 352 use->set_req(j, old_entry); 353 uses_found++; 354 if (loop_phase != NULL) { 355 if (use->is_CFG()) { 356 // When called from beautify_loops() idom is not constructed yet. 357 if (loop_phase->_idom != NULL) 358 loop_phase->set_idom(use, old_entry, loop_phase->dom_depth(use)); 359 } else { 360 loop_phase->set_ctrl(use, old_entry); 361 } 362 } 363 } 364 } 365 i -= uses_found; // we deleted 1 or more copies of this edge 366 } 367 368 // Move predicate. 369 igvn->hash_delete(iff); 370 iff->set_req(0, new_entry); 371 igvn->_worklist.push(iff); 372 373 if (loop_phase != NULL) { 374 // Fix up idom and ctrl. 375 loop_phase->set_ctrl(iff->in(1), new_entry); 376 loop_phase->set_ctrl(iff->in(1)->in(1), new_entry); 377 // When called from beautify_loops() idom is not constructed yet. 378 if (loop_phase->_idom != NULL) 379 loop_phase->set_idom(iff, new_entry, loop_phase->dom_depth(iff)); 380 } 381 382 return predicate_proj; 383 } 384 385 //--------------------------clone_loop_predicates----------------------- 386 // Interface from IGVN 387 Node* PhaseIterGVN::clone_loop_predicates(Node* old_entry, Node* new_entry, bool clone_limit_check) { 388 return PhaseIdealLoop::clone_loop_predicates(old_entry, new_entry, false, clone_limit_check, NULL, this); 389 } 390 Node* PhaseIterGVN::move_loop_predicates(Node* old_entry, Node* new_entry, bool clone_limit_check) { 391 return PhaseIdealLoop::clone_loop_predicates(old_entry, new_entry, true, clone_limit_check, NULL, this); 392 } 393 394 // Interface from PhaseIdealLoop 395 Node* PhaseIdealLoop::clone_loop_predicates(Node* old_entry, Node* new_entry, bool clone_limit_check) { 396 return clone_loop_predicates(old_entry, new_entry, false, clone_limit_check, this, &this->_igvn); 397 } 398 Node* PhaseIdealLoop::move_loop_predicates(Node* old_entry, Node* new_entry, bool clone_limit_check) { 399 return clone_loop_predicates(old_entry, new_entry, true, clone_limit_check, this, &this->_igvn); 400 } 401 402 // Clone loop predicates to cloned loops (peeled, unswitched, split_if). 403 Node* PhaseIdealLoop::clone_loop_predicates(Node* old_entry, Node* new_entry, 404 bool move_predicates, 405 bool clone_limit_check, 406 PhaseIdealLoop* loop_phase, 407 PhaseIterGVN* igvn) { 408 #ifdef ASSERT 409 if (new_entry == NULL || !(new_entry->is_Proj() || new_entry->is_Region() || new_entry->is_SafePoint())) { 410 if (new_entry != NULL) 411 new_entry->dump(); 412 assert(false, "not IfTrue, IfFalse, Region or SafePoint"); 413 } 414 #endif 415 // Search original predicates 416 Node* entry = old_entry; 417 ProjNode* limit_check_proj = NULL; 418 if (LoopLimitCheck) { 419 limit_check_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check); 420 if (limit_check_proj != NULL) { 421 entry = entry->in(0)->in(0); 422 } 423 } 424 if (UseLoopPredicate) { 425 ProjNode* predicate_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate); 426 if (predicate_proj != NULL) { // right pattern that can be used by loop predication 427 if (move_predicates) { 428 new_entry = move_predicate(predicate_proj, new_entry, 429 Deoptimization::Reason_predicate, 430 loop_phase, igvn); 431 assert(new_entry == predicate_proj, "old predicate fall through projection"); 432 } else { 433 // clone predicate 434 new_entry = clone_predicate(predicate_proj, new_entry, 435 Deoptimization::Reason_predicate, 436 loop_phase, igvn); 437 assert(new_entry != NULL && new_entry->is_Proj(), "IfTrue or IfFalse after clone predicate"); 438 } 439 if (TraceLoopPredicate) { 440 tty->print_cr("Loop Predicate %s: ", move_predicates ? "moved" : "cloned"); 441 debug_only( new_entry->in(0)->dump(); ) 442 } 443 } 444 } 445 if (limit_check_proj != NULL && clone_limit_check) { 446 // Clone loop limit check last to insert it before loop. 447 // Don't clone a limit check which was already finalized 448 // for this counted loop (only one limit check is needed). 449 if (move_predicates) { 450 new_entry = move_predicate(limit_check_proj, new_entry, 451 Deoptimization::Reason_loop_limit_check, 452 loop_phase, igvn); 453 assert(new_entry == limit_check_proj, "old limit check fall through projection"); 454 } else { 455 new_entry = clone_predicate(limit_check_proj, new_entry, 456 Deoptimization::Reason_loop_limit_check, 457 loop_phase, igvn); 458 assert(new_entry != NULL && new_entry->is_Proj(), "IfTrue or IfFalse after clone limit check"); 459 } 460 if (TraceLoopLimitCheck) { 461 tty->print_cr("Loop Limit Check %s: ", move_predicates ? "moved" : "cloned"); 462 debug_only( new_entry->in(0)->dump(); ) 463 } 464 } 465 return new_entry; 466 } 467 468 //--------------------------eliminate_loop_predicates----------------------- 469 void PhaseIdealLoop::eliminate_loop_predicates(Node* entry) { 470 if (LoopLimitCheck) { 471 Node* predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check); 472 if (predicate != NULL) { 473 entry = entry->in(0)->in(0); 474 } 475 } 476 if (UseLoopPredicate) { 477 ProjNode* predicate_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate); 478 if (predicate_proj != NULL) { // right pattern that can be used by loop predication 479 Node* n = entry->in(0)->in(1)->in(1); 480 assert(n->Opcode()==Op_Opaque1, "must be"); 481 // Remove Opaque1 node from predicates list. 482 // IGVN will remove this predicate check. 483 _igvn.replace_node(n, n->in(1)); 484 } 485 } 486 } 487 488 //--------------------------skip_loop_predicates------------------------------ 489 // Skip related predicates. 490 Node* PhaseIdealLoop::skip_loop_predicates(Node* entry) { 491 Node* predicate = NULL; 492 if (LoopLimitCheck) { 493 predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check); 494 if (predicate != NULL) { 495 entry = entry->in(0)->in(0); 496 } 497 } 498 if (UseLoopPredicate) { 499 predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate); 500 if (predicate != NULL) { // right pattern that can be used by loop predication 501 IfNode* iff = entry->in(0)->as_If(); 502 ProjNode* uncommon_proj = iff->proj_out(1 - entry->as_Proj()->_con); 503 Node* rgn = uncommon_proj->unique_ctrl_out(); 504 assert(rgn->is_Region() || rgn->is_Call(), "must be a region or call uct"); 505 entry = entry->in(0)->in(0); 506 while (entry != NULL && entry->is_Proj() && entry->in(0)->is_If()) { 507 uncommon_proj = entry->in(0)->as_If()->proj_out(1 - entry->as_Proj()->_con); 508 if (uncommon_proj->unique_ctrl_out() != rgn) 509 break; 510 entry = entry->in(0)->in(0); 511 } 512 } 513 } 514 return entry; 515 } 516 517 //--------------------------find_predicate_insertion_point------------------- 518 // Find a good location to insert a predicate 519 ProjNode* PhaseIdealLoop::find_predicate_insertion_point(Node* start_c, Deoptimization::DeoptReason reason) { 520 if (start_c == NULL || !start_c->is_Proj()) 521 return NULL; 522 if (is_uncommon_trap_if_pattern(start_c->as_Proj(), reason)) { 523 return start_c->as_Proj(); 524 } 525 return NULL; 526 } 527 528 //--------------------------find_predicate------------------------------------ 529 // Find a predicate 530 Node* PhaseIdealLoop::find_predicate(Node* entry) { 531 Node* predicate = NULL; 532 if (LoopLimitCheck) { 533 predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check); 534 if (predicate != NULL) { // right pattern that can be used by loop predication 535 return entry; 536 } 537 } 538 if (UseLoopPredicate) { 539 predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate); 540 if (predicate != NULL) { // right pattern that can be used by loop predication 541 return entry; 542 } 543 } 544 return NULL; 545 } 546 547 //------------------------------Invariance----------------------------------- 548 // Helper class for loop_predication_impl to compute invariance on the fly and 549 // clone invariants. 550 class Invariance : public StackObj { 551 VectorSet _visited, _invariant; 552 Node_Stack _stack; 553 VectorSet _clone_visited; 554 Node_List _old_new; // map of old to new (clone) 555 IdealLoopTree* _lpt; 556 PhaseIdealLoop* _phase; 557 558 // Helper function to set up the invariance for invariance computation 559 // If n is a known invariant, set up directly. Otherwise, look up the 560 // the possibility to push n onto the stack for further processing. 561 void visit(Node* use, Node* n) { 562 if (_lpt->is_invariant(n)) { // known invariant 563 _invariant.set(n->_idx); 564 } else if (!n->is_CFG()) { 565 Node *n_ctrl = _phase->ctrl_or_self(n); 566 Node *u_ctrl = _phase->ctrl_or_self(use); // self if use is a CFG 567 if (_phase->is_dominator(n_ctrl, u_ctrl)) { 568 _stack.push(n, n->in(0) == NULL ? 1 : 0); 569 } 570 } 571 } 572 573 // Compute invariance for "the_node" and (possibly) all its inputs recursively 574 // on the fly 575 void compute_invariance(Node* n) { 576 assert(_visited.test(n->_idx), "must be"); 577 visit(n, n); 578 while (_stack.is_nonempty()) { 579 Node* n = _stack.node(); 580 uint idx = _stack.index(); 581 if (idx == n->req()) { // all inputs are processed 582 _stack.pop(); 583 // n is invariant if it's inputs are all invariant 584 bool all_inputs_invariant = true; 585 for (uint i = 0; i < n->req(); i++) { 586 Node* in = n->in(i); 587 if (in == NULL) continue; 588 assert(_visited.test(in->_idx), "must have visited input"); 589 if (!_invariant.test(in->_idx)) { // bad guy 590 all_inputs_invariant = false; 591 break; 592 } 593 } 594 if (all_inputs_invariant) { 595 _invariant.set(n->_idx); // I am a invariant too 596 } 597 } else { // process next input 598 _stack.set_index(idx + 1); 599 Node* m = n->in(idx); 600 if (m != NULL && !_visited.test_set(m->_idx)) { 601 visit(n, m); 602 } 603 } 604 } 605 } 606 607 // Helper function to set up _old_new map for clone_nodes. 608 // If n is a known invariant, set up directly ("clone" of n == n). 609 // Otherwise, push n onto the stack for real cloning. 610 void clone_visit(Node* n) { 611 assert(_invariant.test(n->_idx), "must be invariant"); 612 if (_lpt->is_invariant(n)) { // known invariant 613 _old_new.map(n->_idx, n); 614 } else { // to be cloned 615 assert(!n->is_CFG(), "should not see CFG here"); 616 _stack.push(n, n->in(0) == NULL ? 1 : 0); 617 } 618 } 619 620 // Clone "n" and (possibly) all its inputs recursively 621 void clone_nodes(Node* n, Node* ctrl) { 622 clone_visit(n); 623 while (_stack.is_nonempty()) { 624 Node* n = _stack.node(); 625 uint idx = _stack.index(); 626 if (idx == n->req()) { // all inputs processed, clone n! 627 _stack.pop(); 628 // clone invariant node 629 Node* n_cl = n->clone(); 630 _old_new.map(n->_idx, n_cl); 631 _phase->register_new_node(n_cl, ctrl); 632 for (uint i = 0; i < n->req(); i++) { 633 Node* in = n_cl->in(i); 634 if (in == NULL) continue; 635 n_cl->set_req(i, _old_new[in->_idx]); 636 } 637 } else { // process next input 638 _stack.set_index(idx + 1); 639 Node* m = n->in(idx); 640 if (m != NULL && !_clone_visited.test_set(m->_idx)) { 641 clone_visit(m); // visit the input 642 } 643 } 644 } 645 } 646 647 public: 648 Invariance(Arena* area, IdealLoopTree* lpt) : 649 _lpt(lpt), _phase(lpt->_phase), 650 _visited(area), _invariant(area), _stack(area, 10 /* guess */), 651 _clone_visited(area), _old_new(area) 652 {} 653 654 // Map old to n for invariance computation and clone 655 void map_ctrl(Node* old, Node* n) { 656 assert(old->is_CFG() && n->is_CFG(), "must be"); 657 _old_new.map(old->_idx, n); // "clone" of old is n 658 _invariant.set(old->_idx); // old is invariant 659 _clone_visited.set(old->_idx); 660 } 661 662 // Driver function to compute invariance 663 bool is_invariant(Node* n) { 664 if (!_visited.test_set(n->_idx)) 665 compute_invariance(n); 666 return (_invariant.test(n->_idx) != 0); 667 } 668 669 // Driver function to clone invariant 670 Node* clone(Node* n, Node* ctrl) { 671 assert(ctrl->is_CFG(), "must be"); 672 assert(_invariant.test(n->_idx), "must be an invariant"); 673 if (!_clone_visited.test(n->_idx)) 674 clone_nodes(n, ctrl); 675 return _old_new[n->_idx]; 676 } 677 }; 678 679 //------------------------------is_range_check_if ----------------------------------- 680 // Returns true if the predicate of iff is in "scale*iv + offset u< load_range(ptr)" format 681 // Note: this function is particularly designed for loop predication. We require load_range 682 // and offset to be loop invariant computed on the fly by "invar" 683 bool IdealLoopTree::is_range_check_if(IfNode *iff, PhaseIdealLoop *phase, Invariance& invar) const { 684 if (!is_loop_exit(iff)) { 685 return false; 686 } 687 if (!iff->in(1)->is_Bool()) { 688 return false; 689 } 690 const BoolNode *bol = iff->in(1)->as_Bool(); 691 if (bol->_test._test != BoolTest::lt) { 692 return false; 693 } 694 if (!bol->in(1)->is_Cmp()) { 695 return false; 696 } 697 const CmpNode *cmp = bol->in(1)->as_Cmp(); 698 if (cmp->Opcode() != Op_CmpU) { 699 return false; 700 } 701 Node* range = cmp->in(2); 702 if (range->Opcode() != Op_LoadRange) { 703 const TypeInt* tint = phase->_igvn.type(range)->isa_int(); 704 if (tint == NULL || tint->empty() || tint->_lo < 0) { 705 // Allow predication on positive values that aren't LoadRanges. 706 // This allows optimization of loops where the length of the 707 // array is a known value and doesn't need to be loaded back 708 // from the array. 709 return false; 710 } 711 } 712 if (!invar.is_invariant(range)) { 713 return false; 714 } 715 Node *iv = _head->as_CountedLoop()->phi(); 716 int scale = 0; 717 Node *offset = NULL; 718 if (!phase->is_scaled_iv_plus_offset(cmp->in(1), iv, &scale, &offset)) { 719 return false; 720 } 721 if (offset && !invar.is_invariant(offset)) { // offset must be invariant 722 return false; 723 } 724 return true; 725 } 726 727 //------------------------------rc_predicate----------------------------------- 728 // Create a range check predicate 729 // 730 // for (i = init; i < limit; i += stride) { 731 // a[scale*i+offset] 732 // } 733 // 734 // Compute max(scale*i + offset) for init <= i < limit and build the predicate 735 // as "max(scale*i + offset) u< a.length". 736 // 737 // There are two cases for max(scale*i + offset): 738 // (1) stride*scale > 0 739 // max(scale*i + offset) = scale*(limit-stride) + offset 740 // (2) stride*scale < 0 741 // max(scale*i + offset) = scale*init + offset 742 BoolNode* PhaseIdealLoop::rc_predicate(IdealLoopTree *loop, Node* ctrl, 743 int scale, Node* offset, 744 Node* init, Node* limit, Node* stride, 745 Node* range, bool upper) { 746 stringStream* predString = NULL; 747 if (TraceLoopPredicate) { 748 predString = new stringStream(); 749 predString->print("rc_predicate "); 750 } 751 752 Node* max_idx_expr = init; 753 int stride_con = stride->get_int(); 754 if ((stride_con > 0) == (scale > 0) == upper) { 755 if (LoopLimitCheck) { 756 // With LoopLimitCheck limit is not exact. 757 // Calculate exact limit here. 758 // Note, counted loop's test is '<' or '>'. 759 limit = exact_limit(loop); 760 max_idx_expr = new (C, 3) SubINode(limit, stride); 761 register_new_node(max_idx_expr, ctrl); 762 if (TraceLoopPredicate) predString->print("(limit - stride) "); 763 } else { 764 max_idx_expr = new (C, 3) SubINode(limit, stride); 765 register_new_node(max_idx_expr, ctrl); 766 if (TraceLoopPredicate) predString->print("(limit - stride) "); 767 } 768 } else { 769 if (TraceLoopPredicate) predString->print("init "); 770 } 771 772 if (scale != 1) { 773 ConNode* con_scale = _igvn.intcon(scale); 774 max_idx_expr = new (C, 3) MulINode(max_idx_expr, con_scale); 775 register_new_node(max_idx_expr, ctrl); 776 if (TraceLoopPredicate) predString->print("* %d ", scale); 777 } 778 779 if (offset && (!offset->is_Con() || offset->get_int() != 0)){ 780 max_idx_expr = new (C, 3) AddINode(max_idx_expr, offset); 781 register_new_node(max_idx_expr, ctrl); 782 if (TraceLoopPredicate) 783 if (offset->is_Con()) predString->print("+ %d ", offset->get_int()); 784 else predString->print("+ offset "); 785 } 786 787 CmpUNode* cmp = new (C, 3) CmpUNode(max_idx_expr, range); 788 register_new_node(cmp, ctrl); 789 BoolNode* bol = new (C, 2) BoolNode(cmp, BoolTest::lt); 790 register_new_node(bol, ctrl); 791 792 if (TraceLoopPredicate) { 793 predString->print_cr("<u range"); 794 tty->print(predString->as_string()); 795 } 796 return bol; 797 } 798 799 //------------------------------ loop_predication_impl-------------------------- 800 // Insert loop predicates for null checks and range checks 801 bool PhaseIdealLoop::loop_predication_impl(IdealLoopTree *loop) { 802 if (!UseLoopPredicate) return false; 803 804 if (!loop->_head->is_Loop()) { 805 // Could be a simple region when irreducible loops are present. 806 return false; 807 } 808 LoopNode* head = loop->_head->as_Loop(); 809 810 if (head->unique_ctrl_out()->Opcode() == Op_NeverBranch) { 811 // do nothing for infinite loops 812 return false; 813 } 814 815 CountedLoopNode *cl = NULL; 816 if (head->is_CountedLoop()) { 817 cl = head->as_CountedLoop(); 818 // do nothing for iteration-splitted loops 819 if (!cl->is_normal_loop()) return false; 820 } 821 822 Node* entry = head->in(LoopNode::EntryControl); 823 ProjNode *predicate_proj = NULL; 824 // Loop limit check predicate should be near the loop. 825 if (LoopLimitCheck) { 826 predicate_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check); 827 if (predicate_proj != NULL) 828 entry = predicate_proj->in(0)->in(0); 829 } 830 831 predicate_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate); 832 if (!predicate_proj) { 833 #ifndef PRODUCT 834 if (TraceLoopPredicate) { 835 tty->print("missing predicate:"); 836 loop->dump_head(); 837 head->dump(1); 838 } 839 #endif 840 return false; 841 } 842 ConNode* zero = _igvn.intcon(0); 843 set_ctrl(zero, C->root()); 844 845 ResourceArea *area = Thread::current()->resource_area(); 846 Invariance invar(area, loop); 847 848 // Create list of if-projs such that a newer proj dominates all older 849 // projs in the list, and they all dominate loop->tail() 850 Node_List if_proj_list(area); 851 Node *current_proj = loop->tail(); //start from tail 852 while (current_proj != head) { 853 if (loop == get_loop(current_proj) && // still in the loop ? 854 current_proj->is_Proj() && // is a projection ? 855 current_proj->in(0)->Opcode() == Op_If) { // is a if projection ? 856 if_proj_list.push(current_proj); 857 } 858 current_proj = idom(current_proj); 859 } 860 861 bool hoisted = false; // true if at least one proj is promoted 862 while (if_proj_list.size() > 0) { 863 // Following are changed to nonnull when a predicate can be hoisted 864 ProjNode* new_predicate_proj = NULL; 865 866 ProjNode* proj = if_proj_list.pop()->as_Proj(); 867 IfNode* iff = proj->in(0)->as_If(); 868 869 if (!is_uncommon_trap_if_pattern(proj, Deoptimization::Reason_none)) { 870 if (loop->is_loop_exit(iff)) { 871 // stop processing the remaining projs in the list because the execution of them 872 // depends on the condition of "iff" (iff->in(1)). 873 break; 874 } else { 875 // Both arms are inside the loop. There are two cases: 876 // (1) there is one backward branch. In this case, any remaining proj 877 // in the if_proj list post-dominates "iff". So, the condition of "iff" 878 // does not determine the execution the remining projs directly, and we 879 // can safely continue. 880 // (2) both arms are forwarded, i.e. a diamond shape. In this case, "proj" 881 // does not dominate loop->tail(), so it can not be in the if_proj list. 882 continue; 883 } 884 } 885 886 Node* test = iff->in(1); 887 if (!test->is_Bool()){ //Conv2B, ... 888 continue; 889 } 890 BoolNode* bol = test->as_Bool(); 891 if (invar.is_invariant(bol)) { 892 // Invariant test 893 new_predicate_proj = create_new_if_for_predicate(predicate_proj, NULL, 894 Deoptimization::Reason_predicate); 895 Node* ctrl = new_predicate_proj->in(0)->as_If()->in(0); 896 BoolNode* new_predicate_bol = invar.clone(bol, ctrl)->as_Bool(); 897 898 // Negate test if necessary 899 bool negated = false; 900 if (proj->_con != predicate_proj->_con) { 901 new_predicate_bol = new (C, 2) BoolNode(new_predicate_bol->in(1), new_predicate_bol->_test.negate()); 902 register_new_node(new_predicate_bol, ctrl); 903 negated = true; 904 } 905 IfNode* new_predicate_iff = new_predicate_proj->in(0)->as_If(); 906 _igvn.hash_delete(new_predicate_iff); 907 new_predicate_iff->set_req(1, new_predicate_bol); 908 #ifndef PRODUCT 909 if (TraceLoopPredicate) { 910 tty->print("Predicate invariant if%s: %d ", negated ? " negated" : "", new_predicate_iff->_idx); 911 loop->dump_head(); 912 } else if (TraceLoopOpts) { 913 tty->print("Predicate IC "); 914 loop->dump_head(); 915 } 916 #endif 917 } else if (cl != NULL && loop->is_range_check_if(iff, this, invar)) { 918 assert(proj->_con == predicate_proj->_con, "must match"); 919 920 // Range check for counted loops 921 const Node* cmp = bol->in(1)->as_Cmp(); 922 Node* idx = cmp->in(1); 923 assert(!invar.is_invariant(idx), "index is variant"); 924 Node* rng = cmp->in(2); 925 assert(rng->Opcode() == Op_LoadRange || _igvn.type(rng)->is_int() >= 0, "must be"); 926 assert(invar.is_invariant(rng), "range must be invariant"); 927 int scale = 1; 928 Node* offset = zero; 929 bool ok = is_scaled_iv_plus_offset(idx, cl->phi(), &scale, &offset); 930 assert(ok, "must be index expression"); 931 932 Node* init = cl->init_trip(); 933 Node* limit = cl->limit(); 934 Node* stride = cl->stride(); 935 936 // Build if's for the upper and lower bound tests. The 937 // lower_bound test will dominate the upper bound test and all 938 // cloned or created nodes will use the lower bound test as 939 // their declared control. 940 ProjNode* lower_bound_proj = create_new_if_for_predicate(predicate_proj, NULL, Deoptimization::Reason_predicate); 941 ProjNode* upper_bound_proj = create_new_if_for_predicate(predicate_proj, NULL, Deoptimization::Reason_predicate); 942 assert(upper_bound_proj->in(0)->as_If()->in(0) == lower_bound_proj, "should dominate"); 943 Node *ctrl = lower_bound_proj->in(0)->as_If()->in(0); 944 945 // Perform cloning to keep Invariance state correct since the 946 // late schedule will place invariant things in the loop. 947 rng = invar.clone(rng, ctrl); 948 if (offset && offset != zero) { 949 assert(invar.is_invariant(offset), "offset must be loop invariant"); 950 offset = invar.clone(offset, ctrl); 951 } 952 953 // Test the lower bound 954 Node* lower_bound_bol = rc_predicate(loop, ctrl, scale, offset, init, limit, stride, rng, false); 955 IfNode* lower_bound_iff = lower_bound_proj->in(0)->as_If(); 956 _igvn.hash_delete(lower_bound_iff); 957 lower_bound_iff->set_req(1, lower_bound_bol); 958 if (TraceLoopPredicate) tty->print_cr("lower bound check if: %d", lower_bound_iff->_idx); 959 960 // Test the upper bound 961 Node* upper_bound_bol = rc_predicate(loop, ctrl, scale, offset, init, limit, stride, rng, true); 962 IfNode* upper_bound_iff = upper_bound_proj->in(0)->as_If(); 963 _igvn.hash_delete(upper_bound_iff); 964 upper_bound_iff->set_req(1, upper_bound_bol); 965 if (TraceLoopPredicate) tty->print_cr("upper bound check if: %d", lower_bound_iff->_idx); 966 967 // Fall through into rest of the clean up code which will move 968 // any dependent nodes onto the upper bound test. 969 new_predicate_proj = upper_bound_proj; 970 971 #ifndef PRODUCT 972 if (TraceLoopOpts && !TraceLoopPredicate) { 973 tty->print("Predicate RC "); 974 loop->dump_head(); 975 } 976 #endif 977 } else { 978 // Loop variant check (for example, range check in non-counted loop) 979 // with uncommon trap. 980 continue; 981 } 982 assert(new_predicate_proj != NULL, "sanity"); 983 // Success - attach condition (new_predicate_bol) to predicate if 984 invar.map_ctrl(proj, new_predicate_proj); // so that invariance test can be appropriate 985 986 // Eliminate the old If in the loop body 987 dominated_by( new_predicate_proj, iff, proj->_con != new_predicate_proj->_con ); 988 989 hoisted = true; 990 C->set_major_progress(); 991 } // end while 992 993 #ifndef PRODUCT 994 // report that the loop predication has been actually performed 995 // for this loop 996 if (TraceLoopPredicate && hoisted) { 997 tty->print("Loop Predication Performed:"); 998 loop->dump_head(); 999 } 1000 #endif 1001 1002 return hoisted; 1003 } 1004 1005 //------------------------------loop_predication-------------------------------- 1006 // driver routine for loop predication optimization 1007 bool IdealLoopTree::loop_predication( PhaseIdealLoop *phase) { 1008 bool hoisted = false; 1009 // Recursively promote predicates 1010 if (_child) { 1011 hoisted = _child->loop_predication( phase); 1012 } 1013 1014 // self 1015 if (!_irreducible && !tail()->is_top()) { 1016 hoisted |= phase->loop_predication_impl(this); 1017 } 1018 1019 if (_next) { //sibling 1020 hoisted |= _next->loop_predication( phase); 1021 } 1022 1023 return hoisted; 1024 }