1 /* 2 * Copyright (c) 1998, 2024, 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 "ci/ciMethodData.hpp" 27 #include "compiler/compileLog.hpp" 28 #include "gc/shared/barrierSet.hpp" 29 #include "gc/shared/c2/barrierSetC2.hpp" 30 #include "libadt/vectset.hpp" 31 #include "memory/allocation.inline.hpp" 32 #include "memory/resourceArea.hpp" 33 #include "opto/addnode.hpp" 34 #include "opto/arraycopynode.hpp" 35 #include "opto/callnode.hpp" 36 #include "opto/castnode.hpp" 37 #include "opto/connode.hpp" 38 #include "opto/convertnode.hpp" 39 #include "opto/divnode.hpp" 40 #include "opto/idealGraphPrinter.hpp" 41 #include "opto/loopnode.hpp" 42 #include "opto/movenode.hpp" 43 #include "opto/mulnode.hpp" 44 #include "opto/opaquenode.hpp" 45 #include "opto/predicates.hpp" 46 #include "opto/rootnode.hpp" 47 #include "opto/runtime.hpp" 48 #include "opto/vectorization.hpp" 49 #include "runtime/sharedRuntime.hpp" 50 #include "utilities/checkedCast.hpp" 51 #include "utilities/powerOfTwo.hpp" 52 53 //============================================================================= 54 //--------------------------is_cloop_ind_var----------------------------------- 55 // Determine if a node is a counted loop induction variable. 56 // NOTE: The method is declared in "node.hpp". 57 bool Node::is_cloop_ind_var() const { 58 return (is_Phi() && 59 as_Phi()->region()->is_CountedLoop() && 60 as_Phi()->region()->as_CountedLoop()->phi() == this); 61 } 62 63 //============================================================================= 64 //------------------------------dump_spec-------------------------------------- 65 // Dump special per-node info 66 #ifndef PRODUCT 67 void LoopNode::dump_spec(outputStream *st) const { 68 RegionNode::dump_spec(st); 69 if (is_inner_loop()) st->print( "inner " ); 70 if (is_partial_peel_loop()) st->print( "partial_peel " ); 71 if (partial_peel_has_failed()) st->print( "partial_peel_failed " ); 72 } 73 #endif 74 75 //------------------------------is_valid_counted_loop------------------------- 76 bool LoopNode::is_valid_counted_loop(BasicType bt) const { 77 if (is_BaseCountedLoop() && as_BaseCountedLoop()->bt() == bt) { 78 BaseCountedLoopNode* l = as_BaseCountedLoop(); 79 BaseCountedLoopEndNode* le = l->loopexit_or_null(); 80 if (le != nullptr && 81 le->proj_out_or_null(1 /* true */) == l->in(LoopNode::LoopBackControl)) { 82 Node* phi = l->phi(); 83 Node* exit = le->proj_out_or_null(0 /* false */); 84 if (exit != nullptr && exit->Opcode() == Op_IfFalse && 85 phi != nullptr && phi->is_Phi() && 86 phi->in(LoopNode::LoopBackControl) == l->incr() && 87 le->loopnode() == l && le->stride_is_con()) { 88 return true; 89 } 90 } 91 } 92 return false; 93 } 94 95 //------------------------------get_early_ctrl--------------------------------- 96 // Compute earliest legal control 97 Node *PhaseIdealLoop::get_early_ctrl( Node *n ) { 98 assert( !n->is_Phi() && !n->is_CFG(), "this code only handles data nodes" ); 99 uint i; 100 Node *early; 101 if (n->in(0) && !n->is_expensive()) { 102 early = n->in(0); 103 if (!early->is_CFG()) // Might be a non-CFG multi-def 104 early = get_ctrl(early); // So treat input as a straight data input 105 i = 1; 106 } else { 107 early = get_ctrl(n->in(1)); 108 i = 2; 109 } 110 uint e_d = dom_depth(early); 111 assert( early, "" ); 112 for (; i < n->req(); i++) { 113 Node *cin = get_ctrl(n->in(i)); 114 assert( cin, "" ); 115 // Keep deepest dominator depth 116 uint c_d = dom_depth(cin); 117 if (c_d > e_d) { // Deeper guy? 118 early = cin; // Keep deepest found so far 119 e_d = c_d; 120 } else if (c_d == e_d && // Same depth? 121 early != cin) { // If not equal, must use slower algorithm 122 // If same depth but not equal, one _must_ dominate the other 123 // and we want the deeper (i.e., dominated) guy. 124 Node *n1 = early; 125 Node *n2 = cin; 126 while (1) { 127 n1 = idom(n1); // Walk up until break cycle 128 n2 = idom(n2); 129 if (n1 == cin || // Walked early up to cin 130 dom_depth(n2) < c_d) 131 break; // early is deeper; keep him 132 if (n2 == early || // Walked cin up to early 133 dom_depth(n1) < c_d) { 134 early = cin; // cin is deeper; keep him 135 break; 136 } 137 } 138 e_d = dom_depth(early); // Reset depth register cache 139 } 140 } 141 142 // Return earliest legal location 143 assert(early == find_non_split_ctrl(early), "unexpected early control"); 144 145 if (n->is_expensive() && !_verify_only && !_verify_me) { 146 assert(n->in(0), "should have control input"); 147 early = get_early_ctrl_for_expensive(n, early); 148 } 149 150 return early; 151 } 152 153 //------------------------------get_early_ctrl_for_expensive--------------------------------- 154 // Move node up the dominator tree as high as legal while still beneficial 155 Node *PhaseIdealLoop::get_early_ctrl_for_expensive(Node *n, Node* earliest) { 156 assert(n->in(0) && n->is_expensive(), "expensive node with control input here"); 157 assert(OptimizeExpensiveOps, "optimization off?"); 158 159 Node* ctl = n->in(0); 160 assert(ctl->is_CFG(), "expensive input 0 must be cfg"); 161 uint min_dom_depth = dom_depth(earliest); 162 #ifdef ASSERT 163 if (!is_dominator(ctl, earliest) && !is_dominator(earliest, ctl)) { 164 dump_bad_graph("Bad graph detected in get_early_ctrl_for_expensive", n, earliest, ctl); 165 assert(false, "Bad graph detected in get_early_ctrl_for_expensive"); 166 } 167 #endif 168 if (dom_depth(ctl) < min_dom_depth) { 169 return earliest; 170 } 171 172 while (1) { 173 Node *next = ctl; 174 // Moving the node out of a loop on the projection of a If 175 // confuses loop predication. So once we hit a Loop in a If branch 176 // that doesn't branch to an UNC, we stop. The code that process 177 // expensive nodes will notice the loop and skip over it to try to 178 // move the node further up. 179 if (ctl->is_CountedLoop() && ctl->in(1) != nullptr && ctl->in(1)->in(0) != nullptr && ctl->in(1)->in(0)->is_If()) { 180 if (!ctl->in(1)->as_Proj()->is_uncommon_trap_if_pattern()) { 181 break; 182 } 183 next = idom(ctl->in(1)->in(0)); 184 } else if (ctl->is_Proj()) { 185 // We only move it up along a projection if the projection is 186 // the single control projection for its parent: same code path, 187 // if it's a If with UNC or fallthrough of a call. 188 Node* parent_ctl = ctl->in(0); 189 if (parent_ctl == nullptr) { 190 break; 191 } else if (parent_ctl->is_CountedLoopEnd() && parent_ctl->as_CountedLoopEnd()->loopnode() != nullptr) { 192 next = parent_ctl->as_CountedLoopEnd()->loopnode()->init_control(); 193 } else if (parent_ctl->is_If()) { 194 if (!ctl->as_Proj()->is_uncommon_trap_if_pattern()) { 195 break; 196 } 197 assert(idom(ctl) == parent_ctl, "strange"); 198 next = idom(parent_ctl); 199 } else if (ctl->is_CatchProj()) { 200 if (ctl->as_Proj()->_con != CatchProjNode::fall_through_index) { 201 break; 202 } 203 assert(parent_ctl->in(0)->in(0)->is_Call(), "strange graph"); 204 next = parent_ctl->in(0)->in(0)->in(0); 205 } else { 206 // Check if parent control has a single projection (this 207 // control is the only possible successor of the parent 208 // control). If so, we can try to move the node above the 209 // parent control. 210 int nb_ctl_proj = 0; 211 for (DUIterator_Fast imax, i = parent_ctl->fast_outs(imax); i < imax; i++) { 212 Node *p = parent_ctl->fast_out(i); 213 if (p->is_Proj() && p->is_CFG()) { 214 nb_ctl_proj++; 215 if (nb_ctl_proj > 1) { 216 break; 217 } 218 } 219 } 220 221 if (nb_ctl_proj > 1) { 222 break; 223 } 224 assert(parent_ctl->is_Start() || parent_ctl->is_MemBar() || parent_ctl->is_Call() || 225 BarrierSet::barrier_set()->barrier_set_c2()->is_gc_barrier_node(parent_ctl), "unexpected node"); 226 assert(idom(ctl) == parent_ctl, "strange"); 227 next = idom(parent_ctl); 228 } 229 } else { 230 next = idom(ctl); 231 } 232 if (next->is_Root() || next->is_Start() || dom_depth(next) < min_dom_depth) { 233 break; 234 } 235 ctl = next; 236 } 237 238 if (ctl != n->in(0)) { 239 _igvn.replace_input_of(n, 0, ctl); 240 _igvn.hash_insert(n); 241 } 242 243 return ctl; 244 } 245 246 247 //------------------------------set_early_ctrl--------------------------------- 248 // Set earliest legal control 249 void PhaseIdealLoop::set_early_ctrl(Node* n, bool update_body) { 250 Node *early = get_early_ctrl(n); 251 252 // Record earliest legal location 253 set_ctrl(n, early); 254 IdealLoopTree *loop = get_loop(early); 255 if (update_body && loop->_child == nullptr) { 256 loop->_body.push(n); 257 } 258 } 259 260 //------------------------------set_subtree_ctrl------------------------------- 261 // set missing _ctrl entries on new nodes 262 void PhaseIdealLoop::set_subtree_ctrl(Node* n, bool update_body) { 263 // Already set? Get out. 264 if (_loop_or_ctrl[n->_idx]) return; 265 // Recursively set _loop_or_ctrl array to indicate where the Node goes 266 uint i; 267 for (i = 0; i < n->req(); ++i) { 268 Node *m = n->in(i); 269 if (m && m != C->root()) { 270 set_subtree_ctrl(m, update_body); 271 } 272 } 273 274 // Fixup self 275 set_early_ctrl(n, update_body); 276 } 277 278 IdealLoopTree* PhaseIdealLoop::insert_outer_loop(IdealLoopTree* loop, LoopNode* outer_l, Node* outer_ift) { 279 IdealLoopTree* outer_ilt = new IdealLoopTree(this, outer_l, outer_ift); 280 IdealLoopTree* parent = loop->_parent; 281 IdealLoopTree* sibling = parent->_child; 282 if (sibling == loop) { 283 parent->_child = outer_ilt; 284 } else { 285 while (sibling->_next != loop) { 286 sibling = sibling->_next; 287 } 288 sibling->_next = outer_ilt; 289 } 290 outer_ilt->_next = loop->_next; 291 outer_ilt->_parent = parent; 292 outer_ilt->_child = loop; 293 outer_ilt->_nest = loop->_nest; 294 loop->_parent = outer_ilt; 295 loop->_next = nullptr; 296 loop->_nest++; 297 assert(loop->_nest <= SHRT_MAX, "sanity"); 298 return outer_ilt; 299 } 300 301 // Create a skeleton strip mined outer loop: a Loop head before the 302 // inner strip mined loop, a safepoint and an exit condition guarded 303 // by an opaque node after the inner strip mined loop with a backedge 304 // to the loop head. The inner strip mined loop is left as it is. Only 305 // once loop optimizations are over, do we adjust the inner loop exit 306 // condition to limit its number of iterations, set the outer loop 307 // exit condition and add Phis to the outer loop head. Some loop 308 // optimizations that operate on the inner strip mined loop need to be 309 // aware of the outer strip mined loop: loop unswitching needs to 310 // clone the outer loop as well as the inner, unrolling needs to only 311 // clone the inner loop etc. No optimizations need to change the outer 312 // strip mined loop as it is only a skeleton. 313 IdealLoopTree* PhaseIdealLoop::create_outer_strip_mined_loop(BoolNode *test, Node *cmp, Node *init_control, 314 IdealLoopTree* loop, float cl_prob, float le_fcnt, 315 Node*& entry_control, Node*& iffalse) { 316 Node* outer_test = _igvn.intcon(0); 317 set_ctrl(outer_test, C->root()); 318 Node *orig = iffalse; 319 iffalse = iffalse->clone(); 320 _igvn.register_new_node_with_optimizer(iffalse); 321 set_idom(iffalse, idom(orig), dom_depth(orig)); 322 323 IfNode *outer_le = new OuterStripMinedLoopEndNode(iffalse, outer_test, cl_prob, le_fcnt); 324 Node *outer_ift = new IfTrueNode (outer_le); 325 Node* outer_iff = orig; 326 _igvn.replace_input_of(outer_iff, 0, outer_le); 327 328 LoopNode *outer_l = new OuterStripMinedLoopNode(C, init_control, outer_ift); 329 entry_control = outer_l; 330 331 IdealLoopTree* outer_ilt = insert_outer_loop(loop, outer_l, outer_ift); 332 333 set_loop(iffalse, outer_ilt); 334 // When this code runs, loop bodies have not yet been populated. 335 const bool body_populated = false; 336 register_control(outer_le, outer_ilt, iffalse, body_populated); 337 register_control(outer_ift, outer_ilt, outer_le, body_populated); 338 set_idom(outer_iff, outer_le, dom_depth(outer_le)); 339 _igvn.register_new_node_with_optimizer(outer_l); 340 set_loop(outer_l, outer_ilt); 341 set_idom(outer_l, init_control, dom_depth(init_control)+1); 342 343 return outer_ilt; 344 } 345 346 void PhaseIdealLoop::insert_loop_limit_check_predicate(ParsePredicateSuccessProj* loop_limit_check_parse_proj, 347 Node* cmp_limit, Node* bol) { 348 assert(loop_limit_check_parse_proj->in(0)->is_ParsePredicate(), "must be parse predicate"); 349 Node* new_predicate_proj = create_new_if_for_predicate(loop_limit_check_parse_proj, nullptr, 350 Deoptimization::Reason_loop_limit_check, 351 Op_If); 352 Node* iff = new_predicate_proj->in(0); 353 cmp_limit = _igvn.register_new_node_with_optimizer(cmp_limit); 354 bol = _igvn.register_new_node_with_optimizer(bol); 355 set_subtree_ctrl(bol, false); 356 _igvn.replace_input_of(iff, 1, bol); 357 358 #ifndef PRODUCT 359 // report that the loop predication has been actually performed 360 // for this loop 361 if (TraceLoopLimitCheck) { 362 tty->print_cr("Counted Loop Limit Check generated:"); 363 debug_only( bol->dump(2); ) 364 } 365 #endif 366 } 367 368 Node* PhaseIdealLoop::loop_exit_control(Node* x, IdealLoopTree* loop) { 369 // Counted loop head must be a good RegionNode with only 3 not null 370 // control input edges: Self, Entry, LoopBack. 371 if (x->in(LoopNode::Self) == nullptr || x->req() != 3 || loop->_irreducible) { 372 return nullptr; 373 } 374 Node *init_control = x->in(LoopNode::EntryControl); 375 Node *back_control = x->in(LoopNode::LoopBackControl); 376 if (init_control == nullptr || back_control == nullptr) { // Partially dead 377 return nullptr; 378 } 379 // Must also check for TOP when looking for a dead loop 380 if (init_control->is_top() || back_control->is_top()) { 381 return nullptr; 382 } 383 384 // Allow funny placement of Safepoint 385 if (back_control->Opcode() == Op_SafePoint) { 386 back_control = back_control->in(TypeFunc::Control); 387 } 388 389 // Controlling test for loop 390 Node *iftrue = back_control; 391 uint iftrue_op = iftrue->Opcode(); 392 if (iftrue_op != Op_IfTrue && 393 iftrue_op != Op_IfFalse) { 394 // I have a weird back-control. Probably the loop-exit test is in 395 // the middle of the loop and I am looking at some trailing control-flow 396 // merge point. To fix this I would have to partially peel the loop. 397 return nullptr; // Obscure back-control 398 } 399 400 // Get boolean guarding loop-back test 401 Node *iff = iftrue->in(0); 402 if (get_loop(iff) != loop || !iff->in(1)->is_Bool()) { 403 return nullptr; 404 } 405 return iftrue; 406 } 407 408 Node* PhaseIdealLoop::loop_exit_test(Node* back_control, IdealLoopTree* loop, Node*& incr, Node*& limit, BoolTest::mask& bt, float& cl_prob) { 409 Node* iftrue = back_control; 410 uint iftrue_op = iftrue->Opcode(); 411 Node* iff = iftrue->in(0); 412 BoolNode* test = iff->in(1)->as_Bool(); 413 bt = test->_test._test; 414 cl_prob = iff->as_If()->_prob; 415 if (iftrue_op == Op_IfFalse) { 416 bt = BoolTest(bt).negate(); 417 cl_prob = 1.0 - cl_prob; 418 } 419 // Get backedge compare 420 Node* cmp = test->in(1); 421 if (!cmp->is_Cmp()) { 422 return nullptr; 423 } 424 425 // Find the trip-counter increment & limit. Limit must be loop invariant. 426 incr = cmp->in(1); 427 limit = cmp->in(2); 428 429 // --------- 430 // need 'loop()' test to tell if limit is loop invariant 431 // --------- 432 433 if (!is_member(loop, get_ctrl(incr))) { // Swapped trip counter and limit? 434 Node* tmp = incr; // Then reverse order into the CmpI 435 incr = limit; 436 limit = tmp; 437 bt = BoolTest(bt).commute(); // And commute the exit test 438 } 439 if (is_member(loop, get_ctrl(limit))) { // Limit must be loop-invariant 440 return nullptr; 441 } 442 if (!is_member(loop, get_ctrl(incr))) { // Trip counter must be loop-variant 443 return nullptr; 444 } 445 return cmp; 446 } 447 448 Node* PhaseIdealLoop::loop_iv_incr(Node* incr, Node* x, IdealLoopTree* loop, Node*& phi_incr) { 449 if (incr->is_Phi()) { 450 if (incr->as_Phi()->region() != x || incr->req() != 3) { 451 return nullptr; // Not simple trip counter expression 452 } 453 phi_incr = incr; 454 incr = phi_incr->in(LoopNode::LoopBackControl); // Assume incr is on backedge of Phi 455 if (!is_member(loop, get_ctrl(incr))) { // Trip counter must be loop-variant 456 return nullptr; 457 } 458 } 459 return incr; 460 } 461 462 Node* PhaseIdealLoop::loop_iv_stride(Node* incr, IdealLoopTree* loop, Node*& xphi) { 463 assert(incr->Opcode() == Op_AddI || incr->Opcode() == Op_AddL, "caller resp."); 464 // Get merge point 465 xphi = incr->in(1); 466 Node *stride = incr->in(2); 467 if (!stride->is_Con()) { // Oops, swap these 468 if (!xphi->is_Con()) { // Is the other guy a constant? 469 return nullptr; // Nope, unknown stride, bail out 470 } 471 Node *tmp = xphi; // 'incr' is commutative, so ok to swap 472 xphi = stride; 473 stride = tmp; 474 } 475 return stride; 476 } 477 478 PhiNode* PhaseIdealLoop::loop_iv_phi(Node* xphi, Node* phi_incr, Node* x, IdealLoopTree* loop) { 479 if (!xphi->is_Phi()) { 480 return nullptr; // Too much math on the trip counter 481 } 482 if (phi_incr != nullptr && phi_incr != xphi) { 483 return nullptr; 484 } 485 PhiNode *phi = xphi->as_Phi(); 486 487 // Phi must be of loop header; backedge must wrap to increment 488 if (phi->region() != x) { 489 return nullptr; 490 } 491 return phi; 492 } 493 494 static int check_stride_overflow(jlong final_correction, const TypeInteger* limit_t, BasicType bt) { 495 if (final_correction > 0) { 496 if (limit_t->lo_as_long() > (max_signed_integer(bt) - final_correction)) { 497 return -1; 498 } 499 if (limit_t->hi_as_long() > (max_signed_integer(bt) - final_correction)) { 500 return 1; 501 } 502 } else { 503 if (limit_t->hi_as_long() < (min_signed_integer(bt) - final_correction)) { 504 return -1; 505 } 506 if (limit_t->lo_as_long() < (min_signed_integer(bt) - final_correction)) { 507 return 1; 508 } 509 } 510 return 0; 511 } 512 513 static bool condition_stride_ok(BoolTest::mask bt, jlong stride_con) { 514 // If the condition is inverted and we will be rolling 515 // through MININT to MAXINT, then bail out. 516 if (bt == BoolTest::eq || // Bail out, but this loop trips at most twice! 517 // Odd stride 518 (bt == BoolTest::ne && stride_con != 1 && stride_con != -1) || 519 // Count down loop rolls through MAXINT 520 ((bt == BoolTest::le || bt == BoolTest::lt) && stride_con < 0) || 521 // Count up loop rolls through MININT 522 ((bt == BoolTest::ge || bt == BoolTest::gt) && stride_con > 0)) { 523 return false; // Bail out 524 } 525 return true; 526 } 527 528 Node* PhaseIdealLoop::loop_nest_replace_iv(Node* iv_to_replace, Node* inner_iv, Node* outer_phi, Node* inner_head, 529 BasicType bt) { 530 Node* iv_as_long; 531 if (bt == T_LONG) { 532 iv_as_long = new ConvI2LNode(inner_iv, TypeLong::INT); 533 register_new_node(iv_as_long, inner_head); 534 } else { 535 iv_as_long = inner_iv; 536 } 537 Node* iv_replacement = AddNode::make(outer_phi, iv_as_long, bt); 538 register_new_node(iv_replacement, inner_head); 539 for (DUIterator_Last imin, i = iv_to_replace->last_outs(imin); i >= imin;) { 540 Node* u = iv_to_replace->last_out(i); 541 #ifdef ASSERT 542 if (!is_dominator(inner_head, ctrl_or_self(u))) { 543 assert(u->is_Phi(), "should be a Phi"); 544 for (uint j = 1; j < u->req(); j++) { 545 if (u->in(j) == iv_to_replace) { 546 assert(is_dominator(inner_head, u->in(0)->in(j)), "iv use above loop?"); 547 } 548 } 549 } 550 #endif 551 _igvn.rehash_node_delayed(u); 552 int nb = u->replace_edge(iv_to_replace, iv_replacement, &_igvn); 553 i -= nb; 554 } 555 return iv_replacement; 556 } 557 558 // Add a Parse Predicate with an uncommon trap on the failing/false path. Normal control will continue on the true path. 559 void PhaseIdealLoop::add_parse_predicate(Deoptimization::DeoptReason reason, Node* inner_head, IdealLoopTree* loop, 560 SafePointNode* sfpt) { 561 if (!C->too_many_traps(reason)) { 562 ParsePredicateNode* parse_predicate = new ParsePredicateNode(inner_head->in(LoopNode::EntryControl), reason, &_igvn); 563 register_control(parse_predicate, loop, inner_head->in(LoopNode::EntryControl)); 564 Node* if_false = new IfFalseNode(parse_predicate); 565 register_control(if_false, _ltree_root, parse_predicate); 566 Node* if_true = new IfTrueNode(parse_predicate); 567 register_control(if_true, loop, parse_predicate); 568 569 int trap_request = Deoptimization::make_trap_request(reason, Deoptimization::Action_maybe_recompile); 570 address call_addr = SharedRuntime::uncommon_trap_blob()->entry_point(); 571 const TypePtr* no_memory_effects = nullptr; 572 JVMState* jvms = sfpt->jvms(); 573 CallNode* unc = new CallStaticJavaNode(OptoRuntime::uncommon_trap_Type(), call_addr, "uncommon_trap", 574 no_memory_effects); 575 576 Node* mem = nullptr; 577 Node* i_o = nullptr; 578 if (sfpt->is_Call()) { 579 mem = sfpt->proj_out(TypeFunc::Memory); 580 i_o = sfpt->proj_out(TypeFunc::I_O); 581 } else { 582 mem = sfpt->memory(); 583 i_o = sfpt->i_o(); 584 } 585 586 Node *frame = new ParmNode(C->start(), TypeFunc::FramePtr); 587 register_new_node(frame, C->start()); 588 Node *ret = new ParmNode(C->start(), TypeFunc::ReturnAdr); 589 register_new_node(ret, C->start()); 590 591 unc->init_req(TypeFunc::Control, if_false); 592 unc->init_req(TypeFunc::I_O, i_o); 593 unc->init_req(TypeFunc::Memory, mem); // may gc ptrs 594 unc->init_req(TypeFunc::FramePtr, frame); 595 unc->init_req(TypeFunc::ReturnAdr, ret); 596 unc->init_req(TypeFunc::Parms+0, _igvn.intcon(trap_request)); 597 unc->set_cnt(PROB_UNLIKELY_MAG(4)); 598 unc->copy_call_debug_info(&_igvn, sfpt); 599 600 for (uint i = TypeFunc::Parms; i < unc->req(); i++) { 601 set_subtree_ctrl(unc->in(i), false); 602 } 603 register_control(unc, _ltree_root, if_false); 604 605 Node* ctrl = new ProjNode(unc, TypeFunc::Control); 606 register_control(ctrl, _ltree_root, unc); 607 Node* halt = new HaltNode(ctrl, frame, "uncommon trap returned which should never happen" PRODUCT_ONLY(COMMA /*reachable*/false)); 608 register_control(halt, _ltree_root, ctrl); 609 _igvn.add_input_to(C->root(), halt); 610 611 _igvn.replace_input_of(inner_head, LoopNode::EntryControl, if_true); 612 set_idom(inner_head, if_true, dom_depth(inner_head)); 613 } 614 } 615 616 // Find a safepoint node that dominates the back edge. We need a 617 // SafePointNode so we can use its jvm state to create empty 618 // predicates. 619 static bool no_side_effect_since_safepoint(Compile* C, Node* x, Node* mem, MergeMemNode* mm, PhaseIdealLoop* phase) { 620 SafePointNode* safepoint = nullptr; 621 for (DUIterator_Fast imax, i = x->fast_outs(imax); i < imax; i++) { 622 Node* u = x->fast_out(i); 623 if (u->is_memory_phi()) { 624 Node* m = u->in(LoopNode::LoopBackControl); 625 if (u->adr_type() == TypePtr::BOTTOM) { 626 if (m->is_MergeMem() && mem->is_MergeMem()) { 627 if (m != mem DEBUG_ONLY(|| true)) { 628 // MergeMemStream can modify m, for example to adjust the length to mem. 629 // This is unfortunate, and probably unnecessary. But as it is, we need 630 // to add m to the igvn worklist, else we may have a modified node that 631 // is not on the igvn worklist. 632 phase->igvn()._worklist.push(m); 633 for (MergeMemStream mms(m->as_MergeMem(), mem->as_MergeMem()); mms.next_non_empty2(); ) { 634 if (!mms.is_empty()) { 635 if (mms.memory() != mms.memory2()) { 636 return false; 637 } 638 #ifdef ASSERT 639 if (mms.alias_idx() != Compile::AliasIdxBot) { 640 mm->set_memory_at(mms.alias_idx(), mem->as_MergeMem()->base_memory()); 641 } 642 #endif 643 } 644 } 645 } 646 } else if (mem->is_MergeMem()) { 647 if (m != mem->as_MergeMem()->base_memory()) { 648 return false; 649 } 650 } else { 651 return false; 652 } 653 } else { 654 if (mem->is_MergeMem()) { 655 if (m != mem->as_MergeMem()->memory_at(C->get_alias_index(u->adr_type()))) { 656 return false; 657 } 658 #ifdef ASSERT 659 mm->set_memory_at(C->get_alias_index(u->adr_type()), mem->as_MergeMem()->base_memory()); 660 #endif 661 } else { 662 if (m != mem) { 663 return false; 664 } 665 } 666 } 667 } 668 } 669 return true; 670 } 671 672 SafePointNode* PhaseIdealLoop::find_safepoint(Node* back_control, Node* x, IdealLoopTree* loop) { 673 IfNode* exit_test = back_control->in(0)->as_If(); 674 SafePointNode* safepoint = nullptr; 675 if (exit_test->in(0)->is_SafePoint() && exit_test->in(0)->outcnt() == 1) { 676 safepoint = exit_test->in(0)->as_SafePoint(); 677 } else { 678 Node* c = back_control; 679 while (c != x && c->Opcode() != Op_SafePoint) { 680 c = idom(c); 681 } 682 683 if (c->Opcode() == Op_SafePoint) { 684 safepoint = c->as_SafePoint(); 685 } 686 687 if (safepoint == nullptr) { 688 return nullptr; 689 } 690 691 Node* mem = safepoint->in(TypeFunc::Memory); 692 693 // We can only use that safepoint if there's no side effect between the backedge and the safepoint. 694 695 // mm is used for book keeping 696 MergeMemNode* mm = nullptr; 697 #ifdef ASSERT 698 if (mem->is_MergeMem()) { 699 mm = mem->clone()->as_MergeMem(); 700 _igvn._worklist.push(mm); 701 for (MergeMemStream mms(mem->as_MergeMem()); mms.next_non_empty(); ) { 702 if (mms.alias_idx() != Compile::AliasIdxBot && loop != get_loop(ctrl_or_self(mms.memory()))) { 703 mm->set_memory_at(mms.alias_idx(), mem->as_MergeMem()->base_memory()); 704 } 705 } 706 } 707 #endif 708 if (!no_side_effect_since_safepoint(C, x, mem, mm, this)) { 709 safepoint = nullptr; 710 } else { 711 assert(mm == nullptr|| _igvn.transform(mm) == mem->as_MergeMem()->base_memory(), "all memory state should have been processed"); 712 } 713 #ifdef ASSERT 714 if (mm != nullptr) { 715 _igvn.remove_dead_node(mm); 716 } 717 #endif 718 } 719 return safepoint; 720 } 721 722 // If the loop has the shape of a counted loop but with a long 723 // induction variable, transform the loop in a loop nest: an inner 724 // loop that iterates for at most max int iterations with an integer 725 // induction variable and an outer loop that iterates over the full 726 // range of long values from the initial loop in (at most) max int 727 // steps. That is: 728 // 729 // x: for (long phi = init; phi < limit; phi += stride) { 730 // // phi := Phi(L, init, incr) 731 // // incr := AddL(phi, longcon(stride)) 732 // long incr = phi + stride; 733 // ... use phi and incr ... 734 // } 735 // 736 // OR: 737 // 738 // x: for (long phi = init; (phi += stride) < limit; ) { 739 // // phi := Phi(L, AddL(init, stride), incr) 740 // // incr := AddL(phi, longcon(stride)) 741 // long incr = phi + stride; 742 // ... use phi and (phi + stride) ... 743 // } 744 // 745 // ==transform=> 746 // 747 // const ulong inner_iters_limit = INT_MAX - stride - 1; //near 0x7FFFFFF0 748 // assert(stride <= inner_iters_limit); // else abort transform 749 // assert((extralong)limit + stride <= LONG_MAX); // else deopt 750 // outer_head: for (long outer_phi = init;;) { 751 // // outer_phi := Phi(outer_head, init, AddL(outer_phi, I2L(inner_phi))) 752 // ulong inner_iters_max = (ulong) MAX(0, ((extralong)limit + stride - outer_phi)); 753 // long inner_iters_actual = MIN(inner_iters_limit, inner_iters_max); 754 // assert(inner_iters_actual == (int)inner_iters_actual); 755 // int inner_phi, inner_incr; 756 // x: for (inner_phi = 0;; inner_phi = inner_incr) { 757 // // inner_phi := Phi(x, intcon(0), inner_incr) 758 // // inner_incr := AddI(inner_phi, intcon(stride)) 759 // inner_incr = inner_phi + stride; 760 // if (inner_incr < inner_iters_actual) { 761 // ... use phi=>(outer_phi+inner_phi) ... 762 // continue; 763 // } 764 // else break; 765 // } 766 // if ((outer_phi+inner_phi) < limit) //OR (outer_phi+inner_incr) < limit 767 // continue; 768 // else break; 769 // } 770 // 771 // The same logic is used to transform an int counted loop that contains long range checks into a loop nest of 2 int 772 // loops with long range checks transformed to int range checks in the inner loop. 773 bool PhaseIdealLoop::create_loop_nest(IdealLoopTree* loop, Node_List &old_new) { 774 Node* x = loop->_head; 775 // Only for inner loops 776 if (loop->_child != nullptr || !x->is_BaseCountedLoop() || x->as_Loop()->is_loop_nest_outer_loop()) { 777 return false; 778 } 779 780 if (x->is_CountedLoop() && !x->as_CountedLoop()->is_main_loop() && !x->as_CountedLoop()->is_normal_loop()) { 781 return false; 782 } 783 784 BaseCountedLoopNode* head = x->as_BaseCountedLoop(); 785 BasicType bt = x->as_BaseCountedLoop()->bt(); 786 787 check_counted_loop_shape(loop, x, bt); 788 789 #ifndef PRODUCT 790 if (bt == T_LONG) { 791 Atomic::inc(&_long_loop_candidates); 792 } 793 #endif 794 795 jlong stride_con_long = head->stride_con(); 796 assert(stride_con_long != 0, "missed some peephole opt"); 797 // We can't iterate for more than max int at a time. 798 if (stride_con_long != (jint)stride_con_long || stride_con_long == min_jint) { 799 assert(bt == T_LONG, "only for long loops"); 800 return false; 801 } 802 jint stride_con = checked_cast<jint>(stride_con_long); 803 // The number of iterations for the integer count loop: guarantee no 804 // overflow: max_jint - stride_con max. -1 so there's no need for a 805 // loop limit check if the exit test is <= or >=. 806 int iters_limit = max_jint - ABS(stride_con) - 1; 807 #ifdef ASSERT 808 if (bt == T_LONG && StressLongCountedLoop > 0) { 809 iters_limit = iters_limit / StressLongCountedLoop; 810 } 811 #endif 812 // At least 2 iterations so counted loop construction doesn't fail 813 if (iters_limit/ABS(stride_con) < 2) { 814 return false; 815 } 816 817 PhiNode* phi = head->phi()->as_Phi(); 818 Node* incr = head->incr(); 819 820 Node* back_control = head->in(LoopNode::LoopBackControl); 821 822 // data nodes on back branch not supported 823 if (back_control->outcnt() > 1) { 824 return false; 825 } 826 827 Node* limit = head->limit(); 828 // We'll need to use the loop limit before the inner loop is entered 829 if (!is_dominator(get_ctrl(limit), x)) { 830 return false; 831 } 832 833 IfNode* exit_test = head->loopexit(); 834 835 assert(back_control->Opcode() == Op_IfTrue, "wrong projection for back edge"); 836 837 Node_List range_checks; 838 iters_limit = extract_long_range_checks(loop, stride_con, iters_limit, phi, range_checks); 839 840 if (bt == T_INT) { 841 // The only purpose of creating a loop nest is to handle long range checks. If there are none, do not proceed further. 842 if (range_checks.size() == 0) { 843 return false; 844 } 845 } 846 847 // Take what we know about the number of iterations of the long counted loop into account when computing the limit of 848 // the inner loop. 849 const Node* init = head->init_trip(); 850 const TypeInteger* lo = _igvn.type(init)->is_integer(bt); 851 const TypeInteger* hi = _igvn.type(limit)->is_integer(bt); 852 if (stride_con < 0) { 853 swap(lo, hi); 854 } 855 if (hi->hi_as_long() <= lo->lo_as_long()) { 856 // not a loop after all 857 return false; 858 } 859 860 if (range_checks.size() > 0) { 861 // This transformation requires peeling one iteration. Also, if it has range checks and they are eliminated by Loop 862 // Predication, then 2 Hoisted Check Predicates are added for one range check. Finally, transforming a long range 863 // check requires extra logic to be executed before the loop is entered and for the outer loop. As a result, the 864 // transformations can't pay off for a small number of iterations: roughly, if the loop runs for 3 iterations, it's 865 // going to execute as many range checks once transformed with range checks eliminated (1 peeled iteration with 866 // range checks + 2 predicates per range checks) as it would have not transformed. It also has to pay for the extra 867 // logic on loop entry and for the outer loop. 868 loop->compute_trip_count(this); 869 if (head->is_CountedLoop() && head->as_CountedLoop()->has_exact_trip_count()) { 870 if (head->as_CountedLoop()->trip_count() <= 3) { 871 return false; 872 } 873 } else { 874 loop->compute_profile_trip_cnt(this); 875 if (!head->is_profile_trip_failed() && head->profile_trip_cnt() <= 3) { 876 return false; 877 } 878 } 879 } 880 881 julong orig_iters = (julong)hi->hi_as_long() - lo->lo_as_long(); 882 iters_limit = checked_cast<int>(MIN2((julong)iters_limit, orig_iters)); 883 884 // We need a safepoint to insert Parse Predicates for the inner loop. 885 SafePointNode* safepoint; 886 if (bt == T_INT && head->as_CountedLoop()->is_strip_mined()) { 887 // Loop is strip mined: use the safepoint of the outer strip mined loop 888 OuterStripMinedLoopNode* outer_loop = head->as_CountedLoop()->outer_loop(); 889 assert(outer_loop != nullptr, "no outer loop"); 890 safepoint = outer_loop->outer_safepoint(); 891 outer_loop->transform_to_counted_loop(&_igvn, this); 892 exit_test = head->loopexit(); 893 } else { 894 safepoint = find_safepoint(back_control, x, loop); 895 } 896 897 Node* exit_branch = exit_test->proj_out(false); 898 Node* entry_control = head->in(LoopNode::EntryControl); 899 900 // Clone the control flow of the loop to build an outer loop 901 Node* outer_back_branch = back_control->clone(); 902 Node* outer_exit_test = new IfNode(exit_test->in(0), exit_test->in(1), exit_test->_prob, exit_test->_fcnt); 903 Node* inner_exit_branch = exit_branch->clone(); 904 905 LoopNode* outer_head = new LoopNode(entry_control, outer_back_branch); 906 IdealLoopTree* outer_ilt = insert_outer_loop(loop, outer_head, outer_back_branch); 907 908 const bool body_populated = true; 909 register_control(outer_head, outer_ilt, entry_control, body_populated); 910 911 _igvn.register_new_node_with_optimizer(inner_exit_branch); 912 set_loop(inner_exit_branch, outer_ilt); 913 set_idom(inner_exit_branch, exit_test, dom_depth(exit_branch)); 914 915 outer_exit_test->set_req(0, inner_exit_branch); 916 register_control(outer_exit_test, outer_ilt, inner_exit_branch, body_populated); 917 918 _igvn.replace_input_of(exit_branch, 0, outer_exit_test); 919 set_idom(exit_branch, outer_exit_test, dom_depth(exit_branch)); 920 921 outer_back_branch->set_req(0, outer_exit_test); 922 register_control(outer_back_branch, outer_ilt, outer_exit_test, body_populated); 923 924 _igvn.replace_input_of(x, LoopNode::EntryControl, outer_head); 925 set_idom(x, outer_head, dom_depth(x)); 926 927 // add an iv phi to the outer loop and use it to compute the inner 928 // loop iteration limit 929 Node* outer_phi = phi->clone(); 930 outer_phi->set_req(0, outer_head); 931 register_new_node(outer_phi, outer_head); 932 933 Node* inner_iters_max = nullptr; 934 if (stride_con > 0) { 935 inner_iters_max = MaxNode::max_diff_with_zero(limit, outer_phi, TypeInteger::bottom(bt), _igvn); 936 } else { 937 inner_iters_max = MaxNode::max_diff_with_zero(outer_phi, limit, TypeInteger::bottom(bt), _igvn); 938 } 939 940 Node* inner_iters_limit = _igvn.integercon(iters_limit, bt); 941 // inner_iters_max may not fit in a signed integer (iterating from 942 // Long.MIN_VALUE to Long.MAX_VALUE for instance). Use an unsigned 943 // min. 944 const TypeInteger* inner_iters_actual_range = TypeInteger::make(0, iters_limit, Type::WidenMin, bt); 945 Node* inner_iters_actual = MaxNode::unsigned_min(inner_iters_max, inner_iters_limit, inner_iters_actual_range, _igvn); 946 947 Node* inner_iters_actual_int; 948 if (bt == T_LONG) { 949 inner_iters_actual_int = new ConvL2INode(inner_iters_actual); 950 _igvn.register_new_node_with_optimizer(inner_iters_actual_int); 951 // When the inner loop is transformed to a counted loop, a loop limit check is not expected to be needed because 952 // the loop limit is less or equal to max_jint - stride - 1 (if stride is positive but a similar argument exists for 953 // a negative stride). We add a CastII here to guarantee that, when the counted loop is created in a subsequent loop 954 // opts pass, an accurate range of values for the limits is found. 955 const TypeInt* inner_iters_actual_int_range = TypeInt::make(0, iters_limit, Type::WidenMin); 956 inner_iters_actual_int = new CastIINode(outer_head, inner_iters_actual_int, inner_iters_actual_int_range, ConstraintCastNode::UnconditionalDependency); 957 _igvn.register_new_node_with_optimizer(inner_iters_actual_int); 958 } else { 959 inner_iters_actual_int = inner_iters_actual; 960 } 961 962 Node* int_zero = _igvn.intcon(0); 963 set_ctrl(int_zero, C->root()); 964 if (stride_con < 0) { 965 inner_iters_actual_int = new SubINode(int_zero, inner_iters_actual_int); 966 _igvn.register_new_node_with_optimizer(inner_iters_actual_int); 967 } 968 969 // Clone the iv data nodes as an integer iv 970 Node* int_stride = _igvn.intcon(stride_con); 971 set_ctrl(int_stride, C->root()); 972 Node* inner_phi = new PhiNode(x->in(0), TypeInt::INT); 973 Node* inner_incr = new AddINode(inner_phi, int_stride); 974 Node* inner_cmp = nullptr; 975 inner_cmp = new CmpINode(inner_incr, inner_iters_actual_int); 976 Node* inner_bol = new BoolNode(inner_cmp, exit_test->in(1)->as_Bool()->_test._test); 977 inner_phi->set_req(LoopNode::EntryControl, int_zero); 978 inner_phi->set_req(LoopNode::LoopBackControl, inner_incr); 979 register_new_node(inner_phi, x); 980 register_new_node(inner_incr, x); 981 register_new_node(inner_cmp, x); 982 register_new_node(inner_bol, x); 983 984 _igvn.replace_input_of(exit_test, 1, inner_bol); 985 986 // Clone inner loop phis to outer loop 987 for (uint i = 0; i < head->outcnt(); i++) { 988 Node* u = head->raw_out(i); 989 if (u->is_Phi() && u != inner_phi && u != phi) { 990 assert(u->in(0) == head, "inconsistent"); 991 Node* clone = u->clone(); 992 clone->set_req(0, outer_head); 993 register_new_node(clone, outer_head); 994 _igvn.replace_input_of(u, LoopNode::EntryControl, clone); 995 } 996 } 997 998 // Replace inner loop long iv phi as inner loop int iv phi + outer 999 // loop iv phi 1000 Node* iv_add = loop_nest_replace_iv(phi, inner_phi, outer_phi, head, bt); 1001 1002 set_subtree_ctrl(inner_iters_actual_int, body_populated); 1003 1004 LoopNode* inner_head = create_inner_head(loop, head, exit_test); 1005 1006 // Summary of steps from initial loop to loop nest: 1007 // 1008 // == old IR nodes => 1009 // 1010 // entry_control: {...} 1011 // x: 1012 // for (long phi = init;;) { 1013 // // phi := Phi(x, init, incr) 1014 // // incr := AddL(phi, longcon(stride)) 1015 // exit_test: 1016 // if (phi < limit) 1017 // back_control: fallthrough; 1018 // else 1019 // exit_branch: break; 1020 // long incr = phi + stride; 1021 // ... use phi and incr ... 1022 // phi = incr; 1023 // } 1024 // 1025 // == new IR nodes (just before final peel) => 1026 // 1027 // entry_control: {...} 1028 // long adjusted_limit = limit + stride; //because phi_incr != nullptr 1029 // assert(!limit_check_required || (extralong)limit + stride == adjusted_limit); // else deopt 1030 // ulong inner_iters_limit = max_jint - ABS(stride) - 1; //near 0x7FFFFFF0 1031 // outer_head: 1032 // for (long outer_phi = init;;) { 1033 // // outer_phi := phi->clone(), in(0):=outer_head, => Phi(outer_head, init, incr) 1034 // // REPLACE phi => AddL(outer_phi, I2L(inner_phi)) 1035 // // REPLACE incr => AddL(outer_phi, I2L(inner_incr)) 1036 // // SO THAT outer_phi := Phi(outer_head, init, AddL(outer_phi, I2L(inner_incr))) 1037 // ulong inner_iters_max = (ulong) MAX(0, ((extralong)adjusted_limit - outer_phi) * SGN(stride)); 1038 // int inner_iters_actual_int = (int) MIN(inner_iters_limit, inner_iters_max) * SGN(stride); 1039 // inner_head: x: //in(1) := outer_head 1040 // int inner_phi; 1041 // for (inner_phi = 0;;) { 1042 // // inner_phi := Phi(x, intcon(0), inner_phi + stride) 1043 // int inner_incr = inner_phi + stride; 1044 // bool inner_bol = (inner_incr < inner_iters_actual_int); 1045 // exit_test: //exit_test->in(1) := inner_bol; 1046 // if (inner_bol) // WAS (phi < limit) 1047 // back_control: fallthrough; 1048 // else 1049 // inner_exit_branch: break; //exit_branch->clone() 1050 // ... use phi=>(outer_phi+inner_phi) ... 1051 // inner_phi = inner_phi + stride; // inner_incr 1052 // } 1053 // outer_exit_test: //exit_test->clone(), in(0):=inner_exit_branch 1054 // if ((outer_phi+inner_phi) < limit) // WAS (phi < limit) 1055 // outer_back_branch: fallthrough; //back_control->clone(), in(0):=outer_exit_test 1056 // else 1057 // exit_branch: break; //in(0) := outer_exit_test 1058 // } 1059 1060 if (bt == T_INT) { 1061 outer_phi = new ConvI2LNode(outer_phi); 1062 register_new_node(outer_phi, outer_head); 1063 } 1064 1065 transform_long_range_checks(stride_con, range_checks, outer_phi, inner_iters_actual_int, 1066 inner_phi, iv_add, inner_head); 1067 // Peel one iteration of the loop and use the safepoint at the end 1068 // of the peeled iteration to insert Parse Predicates. If no well 1069 // positioned safepoint peel to guarantee a safepoint in the outer 1070 // loop. 1071 if (safepoint != nullptr || !loop->_has_call) { 1072 old_new.clear(); 1073 do_peeling(loop, old_new); 1074 } else { 1075 C->set_major_progress(); 1076 } 1077 1078 if (safepoint != nullptr) { 1079 SafePointNode* cloned_sfpt = old_new[safepoint->_idx]->as_SafePoint(); 1080 1081 if (UseLoopPredicate) { 1082 add_parse_predicate(Deoptimization::Reason_predicate, inner_head, outer_ilt, cloned_sfpt); 1083 } 1084 if (UseProfiledLoopPredicate) { 1085 add_parse_predicate(Deoptimization::Reason_profile_predicate, inner_head, outer_ilt, cloned_sfpt); 1086 } 1087 add_parse_predicate(Deoptimization::Reason_loop_limit_check, inner_head, outer_ilt, cloned_sfpt); 1088 } 1089 1090 #ifndef PRODUCT 1091 if (bt == T_LONG) { 1092 Atomic::inc(&_long_loop_nests); 1093 } 1094 #endif 1095 1096 inner_head->mark_loop_nest_inner_loop(); 1097 outer_head->mark_loop_nest_outer_loop(); 1098 1099 return true; 1100 } 1101 1102 int PhaseIdealLoop::extract_long_range_checks(const IdealLoopTree* loop, jint stride_con, int iters_limit, PhiNode* phi, 1103 Node_List& range_checks) { 1104 const jlong min_iters = 2; 1105 jlong reduced_iters_limit = iters_limit; 1106 jlong original_iters_limit = iters_limit; 1107 for (uint i = 0; i < loop->_body.size(); i++) { 1108 Node* c = loop->_body.at(i); 1109 if (c->is_IfProj() && c->in(0)->is_RangeCheck()) { 1110 IfProjNode* if_proj = c->as_IfProj(); 1111 CallStaticJavaNode* call = if_proj->is_uncommon_trap_if_pattern(); 1112 if (call != nullptr) { 1113 Node* range = nullptr; 1114 Node* offset = nullptr; 1115 jlong scale = 0; 1116 if (loop->is_range_check_if(if_proj, this, T_LONG, phi, range, offset, scale) && 1117 loop->is_invariant(range) && loop->is_invariant(offset) && 1118 scale != min_jlong && 1119 original_iters_limit / ABS(scale) >= min_iters * ABS(stride_con)) { 1120 assert(scale == (jint)scale, "scale should be an int"); 1121 reduced_iters_limit = MIN2(reduced_iters_limit, original_iters_limit/ABS(scale)); 1122 range_checks.push(c); 1123 } 1124 } 1125 } 1126 } 1127 1128 return checked_cast<int>(reduced_iters_limit); 1129 } 1130 1131 // One execution of the inner loop covers a sub-range of the entire iteration range of the loop: [A,Z), aka [A=init, 1132 // Z=limit). If the loop has at least one trip (which is the case here), the iteration variable i always takes A as its 1133 // first value, followed by A+S (S is the stride), next A+2S, etc. The limit is exclusive, so that the final value B of 1134 // i is never Z. It will be B=Z-1 if S=1, or B=Z+1 if S=-1. 1135 1136 // If |S|>1 the formula for the last value B would require a floor operation, specifically B=floor((Z-sgn(S)-A)/S)*S+A, 1137 // which is B=Z-sgn(S)U for some U in [1,|S|]. So when S>0, i ranges as i:[A,Z) or i:[A,B=Z-U], or else (in reverse) 1138 // as i:(Z,A] or i:[B=Z+U,A]. It will become important to reason about this inclusive range [A,B] or [B,A]. 1139 1140 // Within the loop there may be many range checks. Each such range check (R.C.) is of the form 0 <= i*K+L < R, where K 1141 // is a scale factor applied to the loop iteration variable i, and L is some offset; K, L, and R are loop-invariant. 1142 // Because R is never negative (see below), this check can always be simplified to an unsigned check i*K+L <u R. 1143 1144 // When a long loop over a 64-bit variable i (outer_iv) is decomposed into a series of shorter sub-loops over a 32-bit 1145 // variable j (inner_iv), j ranges over a shorter interval j:[0,B_2] or [0,Z_2) (assuming S > 0), where the limit is 1146 // chosen to prevent various cases of 32-bit overflow (including multiplications j*K below). In the sub-loop the 1147 // logical value i is offset from j by a 64-bit constant C, so i ranges in i:C+[0,Z_2). 1148 1149 // For S<0, j ranges (in reverse!) through j:[-|B_2|,0] or (-|Z_2|,0]. For either sign of S, we can say i=j+C and j 1150 // ranges through 32-bit ranges [A_2,B_2] or [B_2,A_2] (A_2=0 of course). 1151 1152 // The disjoint union of all the C+[A_2,B_2] ranges from the sub-loops must be identical to the whole range [A,B]. 1153 // Assuming S>0, the first C must be A itself, and the next C value is the previous C+B_2, plus S. If |S|=1, the next 1154 // C value is also the previous C+Z_2. In each sub-loop, j counts from j=A_2=0 and i counts from C+0 and exits at 1155 // j=B_2 (i=C+B_2), just before it gets to i=C+Z_2. Both i and j count up (from C and 0) if S>0; otherwise they count 1156 // down (from C and 0 again). 1157 1158 // Returning to range checks, we see that each i*K+L <u R expands to (C+j)*K+L <u R, or j*K+Q <u R, where Q=(C*K+L). 1159 // (Recall that K and L and R are loop-invariant scale, offset and range values for a particular R.C.) This is still a 1160 // 64-bit comparison, so the range check elimination logic will not apply to it. (The R.C.E. transforms operate only on 1161 // 32-bit indexes and comparisons, because they use 64-bit temporary values to avoid overflow; see 1162 // PhaseIdealLoop::add_constraint.) 1163 1164 // We must transform this comparison so that it gets the same answer, but by means of a 32-bit R.C. (using j not i) of 1165 // the form j*K+L_2 <u32 R_2. Note that L_2 and R_2 must be loop-invariant, but only with respect to the sub-loop. Thus, the 1166 // problem reduces to computing values for L_2 and R_2 (for each R.C. in the loop) in the loop header for the sub-loop. 1167 // Then the standard R.C.E. transforms can take those as inputs and further compute the necessary minimum and maximum 1168 // values for the 32-bit counter j within which the range checks can be eliminated. 1169 1170 // So, given j*K+Q <u R, we need to find some j*K+L_2 <u32 R_2, where L_2 and R_2 fit in 32 bits, and the 32-bit operations do 1171 // not overflow. We also need to cover the cases where i*K+L (= j*K+Q) overflows to a 64-bit negative, since that is 1172 // allowed as an input to the R.C., as long as the R.C. as a whole fails. 1173 1174 // If 32-bit multiplication j*K might overflow, we adjust the sub-loop limit Z_2 closer to zero to reduce j's range. 1175 1176 // For each R.C. j*K+Q <u32 R, the range of mathematical values of j*K+Q in the sub-loop is [Q_min, Q_max], where 1177 // Q_min=Q and Q_max=B_2*K+Q (if S>0 and K>0), Q_min=A_2*K+Q and Q_max=Q (if S<0 and K>0), 1178 // Q_min=B_2*K+Q and Q_max=Q if (S>0 and K<0), Q_min=Q and Q_max=A_2*K+Q (if S<0 and K<0) 1179 1180 // Note that the first R.C. value is always Q=(S*K>0 ? Q_min : Q_max). Also Q_{min,max} = Q + {min,max}(A_2*K,B_2*K). 1181 // If S*K>0 then, as the loop iterations progress, each R.C. value i*K+L = j*K+Q goes up from Q=Q_min towards Q_max. 1182 // If S*K<0 then j*K+Q starts at Q=Q_max and goes down towards Q_min. 1183 1184 // Case A: Some Negatives (but no overflow). 1185 // Number line: 1186 // |s64_min . . . 0 . . . s64_max| 1187 // | . Q_min..Q_max . 0 . . . . | s64 negative 1188 // | . . . . R=0 R< R< R< R< | (against R values) 1189 // | . . . Q_min..0..Q_max . . . | small mixed 1190 // | . . . . R R R< R< R< | (against R values) 1191 // 1192 // R values which are out of range (>Q_max+1) are reduced to max(0,Q_max+1). They are marked on the number line as R<. 1193 // 1194 // So, if Q_min <s64 0, then use this test: 1195 // j*K + s32_trunc(Q_min) <u32 clamp(R, 0, Q_max+1) if S*K>0 (R.C.E. steps upward) 1196 // j*K + s32_trunc(Q_max) <u32 clamp(R, 0, Q_max+1) if S*K<0 (R.C.E. steps downward) 1197 // Both formulas reduce to adding j*K to the 32-bit truncated value of the first R.C. expression value, Q: 1198 // j*K + s32_trunc(Q) <u32 clamp(R, 0, Q_max+1) for all S,K 1199 1200 // If the 32-bit truncation loses information, no harm is done, since certainly the clamp also will return R_2=zero. 1201 1202 // Case B: No Negatives. 1203 // Number line: 1204 // |s64_min . . . 0 . . . s64_max| 1205 // | . . . . 0 Q_min..Q_max . . | small positive 1206 // | . . . . R> R R R< R< | (against R values) 1207 // | . . . . 0 . Q_min..Q_max . | s64 positive 1208 // | . . . . R> R> R R R< | (against R values) 1209 // 1210 // R values which are out of range (<Q_min or >Q_max+1) are reduced as marked: R> up to Q_min, R< down to Q_max+1. 1211 // Then the whole comparison is shifted left by Q_min, so it can take place at zero, which is a nice 32-bit value. 1212 // 1213 // So, if both Q_min, Q_max+1 >=s64 0, then use this test: 1214 // j*K + 0 <u32 clamp(R, Q_min, Q_max+1) - Q_min if S*K>0 1215 // More generally: 1216 // j*K + Q - Q_min <u32 clamp(R, Q_min, Q_max+1) - Q_min for all S,K 1217 1218 // Case C: Overflow in the 64-bit domain 1219 // Number line: 1220 // |..Q_max-2^64 . . 0 . . . Q_min..| s64 overflow 1221 // | . . . . R> R> R> R> R | (against R values) 1222 // 1223 // In this case, Q_min >s64 Q_max+1, even though the mathematical values of Q_min and Q_max+1 are correctly ordered. 1224 // The formulas from the previous case can be used, except that the bad upper bound Q_max is replaced by max_jlong. 1225 // (In fact, we could use any replacement bound from R to max_jlong inclusive, as the input to the clamp function.) 1226 // 1227 // So if Q_min >=s64 0 but Q_max+1 <s64 0, use this test: 1228 // j*K + 0 <u32 clamp(R, Q_min, max_jlong) - Q_min if S*K>0 1229 // More generally: 1230 // j*K + Q - Q_min <u32 clamp(R, Q_min, max_jlong) - Q_min for all S,K 1231 // 1232 // Dropping the bad bound means only Q_min is used to reduce the range of R: 1233 // j*K + Q - Q_min <u32 max(Q_min, R) - Q_min for all S,K 1234 // 1235 // Here the clamp function is a 64-bit min/max that reduces the dynamic range of its R operand to the required [L,H]: 1236 // clamp(X, L, H) := max(L, min(X, H)) 1237 // When degenerately L > H, it returns L not H. 1238 // 1239 // All of the formulas above can be merged into a single one: 1240 // L_clamp = Q_min < 0 ? 0 : Q_min --whether and how far to left-shift 1241 // H_clamp = Q_max+1 < Q_min ? max_jlong : Q_max+1 1242 // = Q_max+1 < 0 && Q_min >= 0 ? max_jlong : Q_max+1 1243 // Q_first = Q = (S*K>0 ? Q_min : Q_max) = (C*K+L) 1244 // R_clamp = clamp(R, L_clamp, H_clamp) --reduced dynamic range 1245 // replacement R.C.: 1246 // j*K + Q_first - L_clamp <u32 R_clamp - L_clamp 1247 // or equivalently: 1248 // j*K + L_2 <u32 R_2 1249 // where 1250 // L_2 = Q_first - L_clamp 1251 // R_2 = R_clamp - L_clamp 1252 // 1253 // Note on why R is never negative: 1254 // 1255 // Various details of this transformation would break badly if R could be negative, so this transformation only 1256 // operates after obtaining hard evidence that R<0 is impossible. For example, if R comes from a LoadRange node, we 1257 // know R cannot be negative. For explicit checks (of both int and long) a proof is constructed in 1258 // inline_preconditions_checkIndex, which triggers an uncommon trap if R<0, then wraps R in a ConstraintCastNode with a 1259 // non-negative type. Later on, when IdealLoopTree::is_range_check_if looks for an optimizable R.C., it checks that 1260 // the type of that R node is non-negative. Any "wild" R node that could be negative is not treated as an optimizable 1261 // R.C., but R values from a.length and inside checkIndex are good to go. 1262 // 1263 void PhaseIdealLoop::transform_long_range_checks(int stride_con, const Node_List &range_checks, Node* outer_phi, 1264 Node* inner_iters_actual_int, Node* inner_phi, 1265 Node* iv_add, LoopNode* inner_head) { 1266 Node* long_zero = _igvn.longcon(0); 1267 set_ctrl(long_zero, C->root()); 1268 Node* int_zero = _igvn.intcon(0); 1269 set_ctrl(int_zero, this->C->root()); 1270 Node* long_one = _igvn.longcon(1); 1271 set_ctrl(long_one, this->C->root()); 1272 Node* int_stride = _igvn.intcon(checked_cast<int>(stride_con)); 1273 set_ctrl(int_stride, this->C->root()); 1274 1275 for (uint i = 0; i < range_checks.size(); i++) { 1276 ProjNode* proj = range_checks.at(i)->as_Proj(); 1277 ProjNode* unc_proj = proj->other_if_proj(); 1278 RangeCheckNode* rc = proj->in(0)->as_RangeCheck(); 1279 jlong scale = 0; 1280 Node* offset = nullptr; 1281 Node* rc_bol = rc->in(1); 1282 Node* rc_cmp = rc_bol->in(1); 1283 if (rc_cmp->Opcode() == Op_CmpU) { 1284 // could be shared and have already been taken care of 1285 continue; 1286 } 1287 bool short_scale = false; 1288 bool ok = is_scaled_iv_plus_offset(rc_cmp->in(1), iv_add, T_LONG, &scale, &offset, &short_scale); 1289 assert(ok, "inconsistent: was tested before"); 1290 Node* range = rc_cmp->in(2); 1291 Node* c = rc->in(0); 1292 Node* entry_control = inner_head->in(LoopNode::EntryControl); 1293 1294 Node* R = range; 1295 Node* K = _igvn.longcon(scale); 1296 set_ctrl(K, this->C->root()); 1297 1298 Node* L = offset; 1299 1300 if (short_scale) { 1301 // This converts: 1302 // (int)i*K + L <u64 R 1303 // with K an int into: 1304 // i*(long)K + L <u64 unsigned_min((long)max_jint + L + 1, R) 1305 // to protect against an overflow of (int)i*K 1306 // 1307 // Because if (int)i*K overflows, there are K,L where: 1308 // (int)i*K + L <u64 R is false because (int)i*K+L overflows to a negative which becomes a huge u64 value. 1309 // But if i*(long)K + L is >u64 (long)max_jint and still is <u64 R, then 1310 // i*(long)K + L <u64 R is true. 1311 // 1312 // As a consequence simply converting i*K + L <u64 R to i*(long)K + L <u64 R could cause incorrect execution. 1313 // 1314 // It's always true that: 1315 // (int)i*K <u64 (long)max_jint + 1 1316 // which implies (int)i*K + L <u64 (long)max_jint + 1 + L 1317 // As a consequence: 1318 // i*(long)K + L <u64 unsigned_min((long)max_jint + L + 1, R) 1319 // is always false in case of overflow of i*K 1320 // 1321 // Note, there are also K,L where i*K overflows and 1322 // i*K + L <u64 R is true, but 1323 // i*(long)K + L <u64 unsigned_min((long)max_jint + L + 1, R) is false 1324 // So this transformation could cause spurious deoptimizations and failed range check elimination 1325 // (but not incorrect execution) for unlikely corner cases with overflow. 1326 // If this causes problems in practice, we could maybe direct execution to a post-loop, instead of deoptimizing. 1327 Node* max_jint_plus_one_long = _igvn.longcon((jlong)max_jint + 1); 1328 set_ctrl(max_jint_plus_one_long, C->root()); 1329 Node* max_range = new AddLNode(max_jint_plus_one_long, L); 1330 register_new_node(max_range, entry_control); 1331 R = MaxNode::unsigned_min(R, max_range, TypeLong::POS, _igvn); 1332 set_subtree_ctrl(R, true); 1333 } 1334 1335 Node* C = outer_phi; 1336 1337 // Start with 64-bit values: 1338 // i*K + L <u64 R 1339 // (C+j)*K + L <u64 R 1340 // j*K + Q <u64 R where Q = Q_first = C*K+L 1341 Node* Q_first = new MulLNode(C, K); 1342 register_new_node(Q_first, entry_control); 1343 Q_first = new AddLNode(Q_first, L); 1344 register_new_node(Q_first, entry_control); 1345 1346 // Compute endpoints of the range of values j*K + Q. 1347 // Q_min = (j=0)*K + Q; Q_max = (j=B_2)*K + Q 1348 Node* Q_min = Q_first; 1349 1350 // Compute the exact ending value B_2 (which is really A_2 if S < 0) 1351 Node* B_2 = new LoopLimitNode(this->C, int_zero, inner_iters_actual_int, int_stride); 1352 register_new_node(B_2, entry_control); 1353 B_2 = new SubINode(B_2, int_stride); 1354 register_new_node(B_2, entry_control); 1355 B_2 = new ConvI2LNode(B_2); 1356 register_new_node(B_2, entry_control); 1357 1358 Node* Q_max = new MulLNode(B_2, K); 1359 register_new_node(Q_max, entry_control); 1360 Q_max = new AddLNode(Q_max, Q_first); 1361 register_new_node(Q_max, entry_control); 1362 1363 if (scale * stride_con < 0) { 1364 swap(Q_min, Q_max); 1365 } 1366 // Now, mathematically, Q_max > Q_min, and they are close enough so that (Q_max-Q_min) fits in 32 bits. 1367 1368 // L_clamp = Q_min < 0 ? 0 : Q_min 1369 Node* Q_min_cmp = new CmpLNode(Q_min, long_zero); 1370 register_new_node(Q_min_cmp, entry_control); 1371 Node* Q_min_bool = new BoolNode(Q_min_cmp, BoolTest::lt); 1372 register_new_node(Q_min_bool, entry_control); 1373 Node* L_clamp = new CMoveLNode(Q_min_bool, Q_min, long_zero, TypeLong::LONG); 1374 register_new_node(L_clamp, entry_control); 1375 // (This could also be coded bitwise as L_clamp = Q_min & ~(Q_min>>63).) 1376 1377 Node* Q_max_plus_one = new AddLNode(Q_max, long_one); 1378 register_new_node(Q_max_plus_one, entry_control); 1379 1380 // H_clamp = Q_max+1 < Q_min ? max_jlong : Q_max+1 1381 // (Because Q_min and Q_max are close, the overflow check could also be encoded as Q_max+1 < 0 & Q_min >= 0.) 1382 Node* max_jlong_long = _igvn.longcon(max_jlong); 1383 set_ctrl(max_jlong_long, this->C->root()); 1384 Node* Q_max_cmp = new CmpLNode(Q_max_plus_one, Q_min); 1385 register_new_node(Q_max_cmp, entry_control); 1386 Node* Q_max_bool = new BoolNode(Q_max_cmp, BoolTest::lt); 1387 register_new_node(Q_max_bool, entry_control); 1388 Node* H_clamp = new CMoveLNode(Q_max_bool, Q_max_plus_one, max_jlong_long, TypeLong::LONG); 1389 register_new_node(H_clamp, entry_control); 1390 // (This could also be coded bitwise as H_clamp = ((Q_max+1)<<1 | M)>>>1 where M = (Q_max+1)>>63 & ~Q_min>>63.) 1391 1392 // R_2 = clamp(R, L_clamp, H_clamp) - L_clamp 1393 // that is: R_2 = clamp(R, L_clamp=0, H_clamp=Q_max) if Q_min < 0 1394 // or else: R_2 = clamp(R, L_clamp, H_clamp) - Q_min if Q_min >= 0 1395 // and also: R_2 = clamp(R, L_clamp, Q_max+1) - L_clamp if Q_min < Q_max+1 (no overflow) 1396 // or else: R_2 = clamp(R, L_clamp, *no limit*)- L_clamp if Q_max+1 < Q_min (overflow) 1397 Node* R_2 = clamp(R, L_clamp, H_clamp); 1398 R_2 = new SubLNode(R_2, L_clamp); 1399 register_new_node(R_2, entry_control); 1400 R_2 = new ConvL2INode(R_2, TypeInt::POS); 1401 register_new_node(R_2, entry_control); 1402 1403 // L_2 = Q_first - L_clamp 1404 // We are subtracting L_clamp from both sides of the <u32 comparison. 1405 // If S*K>0, then Q_first == 0 and the R.C. expression at -L_clamp and steps upward to Q_max-L_clamp. 1406 // If S*K<0, then Q_first != 0 and the R.C. expression starts high and steps downward to Q_min-L_clamp. 1407 Node* L_2 = new SubLNode(Q_first, L_clamp); 1408 register_new_node(L_2, entry_control); 1409 L_2 = new ConvL2INode(L_2, TypeInt::INT); 1410 register_new_node(L_2, entry_control); 1411 1412 // Transform the range check using the computed values L_2/R_2 1413 // from: i*K + L <u64 R 1414 // to: j*K + L_2 <u32 R_2 1415 // that is: 1416 // (j*K + Q_first) - L_clamp <u32 clamp(R, L_clamp, H_clamp) - L_clamp 1417 K = _igvn.intcon(checked_cast<int>(scale)); 1418 set_ctrl(K, this->C->root()); 1419 Node* scaled_iv = new MulINode(inner_phi, K); 1420 register_new_node(scaled_iv, c); 1421 Node* scaled_iv_plus_offset = new AddINode(scaled_iv, L_2); 1422 register_new_node(scaled_iv_plus_offset, c); 1423 1424 Node* new_rc_cmp = new CmpUNode(scaled_iv_plus_offset, R_2); 1425 register_new_node(new_rc_cmp, c); 1426 1427 _igvn.replace_input_of(rc_bol, 1, new_rc_cmp); 1428 } 1429 } 1430 1431 Node* PhaseIdealLoop::clamp(Node* R, Node* L, Node* H) { 1432 Node* min = MaxNode::signed_min(R, H, TypeLong::LONG, _igvn); 1433 set_subtree_ctrl(min, true); 1434 Node* max = MaxNode::signed_max(L, min, TypeLong::LONG, _igvn); 1435 set_subtree_ctrl(max, true); 1436 return max; 1437 } 1438 1439 LoopNode* PhaseIdealLoop::create_inner_head(IdealLoopTree* loop, BaseCountedLoopNode* head, 1440 IfNode* exit_test) { 1441 LoopNode* new_inner_head = new LoopNode(head->in(1), head->in(2)); 1442 IfNode* new_inner_exit = new IfNode(exit_test->in(0), exit_test->in(1), exit_test->_prob, exit_test->_fcnt); 1443 _igvn.register_new_node_with_optimizer(new_inner_head); 1444 _igvn.register_new_node_with_optimizer(new_inner_exit); 1445 loop->_body.push(new_inner_head); 1446 loop->_body.push(new_inner_exit); 1447 loop->_body.yank(head); 1448 loop->_body.yank(exit_test); 1449 set_loop(new_inner_head, loop); 1450 set_loop(new_inner_exit, loop); 1451 set_idom(new_inner_head, idom(head), dom_depth(head)); 1452 set_idom(new_inner_exit, idom(exit_test), dom_depth(exit_test)); 1453 lazy_replace(head, new_inner_head); 1454 lazy_replace(exit_test, new_inner_exit); 1455 loop->_head = new_inner_head; 1456 return new_inner_head; 1457 } 1458 1459 #ifdef ASSERT 1460 void PhaseIdealLoop::check_counted_loop_shape(IdealLoopTree* loop, Node* x, BasicType bt) { 1461 Node* back_control = loop_exit_control(x, loop); 1462 assert(back_control != nullptr, "no back control"); 1463 1464 BoolTest::mask mask = BoolTest::illegal; 1465 float cl_prob = 0; 1466 Node* incr = nullptr; 1467 Node* limit = nullptr; 1468 1469 Node* cmp = loop_exit_test(back_control, loop, incr, limit, mask, cl_prob); 1470 assert(cmp != nullptr && cmp->Opcode() == Op_Cmp(bt), "no exit test"); 1471 1472 Node* phi_incr = nullptr; 1473 incr = loop_iv_incr(incr, x, loop, phi_incr); 1474 assert(incr != nullptr && incr->Opcode() == Op_Add(bt), "no incr"); 1475 1476 Node* xphi = nullptr; 1477 Node* stride = loop_iv_stride(incr, loop, xphi); 1478 1479 assert(stride != nullptr, "no stride"); 1480 1481 PhiNode* phi = loop_iv_phi(xphi, phi_incr, x, loop); 1482 1483 assert(phi != nullptr && phi->in(LoopNode::LoopBackControl) == incr, "No phi"); 1484 1485 jlong stride_con = stride->get_integer_as_long(bt); 1486 1487 assert(condition_stride_ok(mask, stride_con), "illegal condition"); 1488 1489 assert(mask != BoolTest::ne, "unexpected condition"); 1490 assert(phi_incr == nullptr, "bad loop shape"); 1491 assert(cmp->in(1) == incr, "bad exit test shape"); 1492 1493 // Safepoint on backedge not supported 1494 assert(x->in(LoopNode::LoopBackControl)->Opcode() != Op_SafePoint, "no safepoint on backedge"); 1495 } 1496 #endif 1497 1498 #ifdef ASSERT 1499 // convert an int counted loop to a long counted to stress handling of 1500 // long counted loops 1501 bool PhaseIdealLoop::convert_to_long_loop(Node* cmp, Node* phi, IdealLoopTree* loop) { 1502 Unique_Node_List iv_nodes; 1503 Node_List old_new; 1504 iv_nodes.push(cmp); 1505 bool failed = false; 1506 1507 for (uint i = 0; i < iv_nodes.size() && !failed; i++) { 1508 Node* n = iv_nodes.at(i); 1509 switch(n->Opcode()) { 1510 case Op_Phi: { 1511 Node* clone = new PhiNode(n->in(0), TypeLong::LONG); 1512 old_new.map(n->_idx, clone); 1513 break; 1514 } 1515 case Op_CmpI: { 1516 Node* clone = new CmpLNode(nullptr, nullptr); 1517 old_new.map(n->_idx, clone); 1518 break; 1519 } 1520 case Op_AddI: { 1521 Node* clone = new AddLNode(nullptr, nullptr); 1522 old_new.map(n->_idx, clone); 1523 break; 1524 } 1525 case Op_CastII: { 1526 failed = true; 1527 break; 1528 } 1529 default: 1530 DEBUG_ONLY(n->dump()); 1531 fatal("unexpected"); 1532 } 1533 1534 for (uint i = 1; i < n->req(); i++) { 1535 Node* in = n->in(i); 1536 if (in == nullptr) { 1537 continue; 1538 } 1539 if (loop->is_member(get_loop(get_ctrl(in)))) { 1540 iv_nodes.push(in); 1541 } 1542 } 1543 } 1544 1545 if (failed) { 1546 for (uint i = 0; i < iv_nodes.size(); i++) { 1547 Node* n = iv_nodes.at(i); 1548 Node* clone = old_new[n->_idx]; 1549 if (clone != nullptr) { 1550 _igvn.remove_dead_node(clone); 1551 } 1552 } 1553 return false; 1554 } 1555 1556 for (uint i = 0; i < iv_nodes.size(); i++) { 1557 Node* n = iv_nodes.at(i); 1558 Node* clone = old_new[n->_idx]; 1559 for (uint i = 1; i < n->req(); i++) { 1560 Node* in = n->in(i); 1561 if (in == nullptr) { 1562 continue; 1563 } 1564 Node* in_clone = old_new[in->_idx]; 1565 if (in_clone == nullptr) { 1566 assert(_igvn.type(in)->isa_int(), ""); 1567 in_clone = new ConvI2LNode(in); 1568 _igvn.register_new_node_with_optimizer(in_clone); 1569 set_subtree_ctrl(in_clone, false); 1570 } 1571 if (in_clone->in(0) == nullptr) { 1572 in_clone->set_req(0, C->top()); 1573 clone->set_req(i, in_clone); 1574 in_clone->set_req(0, nullptr); 1575 } else { 1576 clone->set_req(i, in_clone); 1577 } 1578 } 1579 _igvn.register_new_node_with_optimizer(clone); 1580 } 1581 set_ctrl(old_new[phi->_idx], phi->in(0)); 1582 1583 for (uint i = 0; i < iv_nodes.size(); i++) { 1584 Node* n = iv_nodes.at(i); 1585 Node* clone = old_new[n->_idx]; 1586 set_subtree_ctrl(clone, false); 1587 Node* m = n->Opcode() == Op_CmpI ? clone : nullptr; 1588 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) { 1589 Node* u = n->fast_out(i); 1590 if (iv_nodes.member(u)) { 1591 continue; 1592 } 1593 if (m == nullptr) { 1594 m = new ConvL2INode(clone); 1595 _igvn.register_new_node_with_optimizer(m); 1596 set_subtree_ctrl(m, false); 1597 } 1598 _igvn.rehash_node_delayed(u); 1599 int nb = u->replace_edge(n, m, &_igvn); 1600 --i, imax -= nb; 1601 } 1602 } 1603 return true; 1604 } 1605 #endif 1606 1607 //------------------------------is_counted_loop-------------------------------- 1608 bool PhaseIdealLoop::is_counted_loop(Node* x, IdealLoopTree*&loop, BasicType iv_bt) { 1609 PhaseGVN *gvn = &_igvn; 1610 1611 Node* back_control = loop_exit_control(x, loop); 1612 if (back_control == nullptr) { 1613 return false; 1614 } 1615 1616 BoolTest::mask bt = BoolTest::illegal; 1617 float cl_prob = 0; 1618 Node* incr = nullptr; 1619 Node* limit = nullptr; 1620 Node* cmp = loop_exit_test(back_control, loop, incr, limit, bt, cl_prob); 1621 if (cmp == nullptr || cmp->Opcode() != Op_Cmp(iv_bt)) { 1622 return false; // Avoid pointer & float & 64-bit compares 1623 } 1624 1625 // Trip-counter increment must be commutative & associative. 1626 if (incr->Opcode() == Op_Cast(iv_bt)) { 1627 incr = incr->in(1); 1628 } 1629 1630 Node* phi_incr = nullptr; 1631 incr = loop_iv_incr(incr, x, loop, phi_incr); 1632 if (incr == nullptr) { 1633 return false; 1634 } 1635 1636 Node* trunc1 = nullptr; 1637 Node* trunc2 = nullptr; 1638 const TypeInteger* iv_trunc_t = nullptr; 1639 Node* orig_incr = incr; 1640 if (!(incr = CountedLoopNode::match_incr_with_optional_truncation(incr, &trunc1, &trunc2, &iv_trunc_t, iv_bt))) { 1641 return false; // Funny increment opcode 1642 } 1643 assert(incr->Opcode() == Op_Add(iv_bt), "wrong increment code"); 1644 1645 Node* xphi = nullptr; 1646 Node* stride = loop_iv_stride(incr, loop, xphi); 1647 1648 if (stride == nullptr) { 1649 return false; 1650 } 1651 1652 if (xphi->Opcode() == Op_Cast(iv_bt)) { 1653 xphi = xphi->in(1); 1654 } 1655 1656 // Stride must be constant 1657 jlong stride_con = stride->get_integer_as_long(iv_bt); 1658 assert(stride_con != 0, "missed some peephole opt"); 1659 1660 PhiNode* phi = loop_iv_phi(xphi, phi_incr, x, loop); 1661 1662 if (phi == nullptr || 1663 (trunc1 == nullptr && phi->in(LoopNode::LoopBackControl) != incr) || 1664 (trunc1 != nullptr && phi->in(LoopNode::LoopBackControl) != trunc1)) { 1665 return false; 1666 } 1667 1668 Node* iftrue = back_control; 1669 uint iftrue_op = iftrue->Opcode(); 1670 Node* iff = iftrue->in(0); 1671 BoolNode* test = iff->in(1)->as_Bool(); 1672 1673 const TypeInteger* limit_t = gvn->type(limit)->is_integer(iv_bt); 1674 if (trunc1 != nullptr) { 1675 // When there is a truncation, we must be sure that after the truncation 1676 // the trip counter will end up higher than the limit, otherwise we are looking 1677 // at an endless loop. Can happen with range checks. 1678 1679 // Example: 1680 // int i = 0; 1681 // while (true) 1682 // sum + = array[i]; 1683 // i++; 1684 // i = i && 0x7fff; 1685 // } 1686 // 1687 // If the array is shorter than 0x8000 this exits through a AIOOB 1688 // - Counted loop transformation is ok 1689 // If the array is longer then this is an endless loop 1690 // - No transformation can be done. 1691 1692 const TypeInteger* incr_t = gvn->type(orig_incr)->is_integer(iv_bt); 1693 if (limit_t->hi_as_long() > incr_t->hi_as_long()) { 1694 // if the limit can have a higher value than the increment (before the phi) 1695 return false; 1696 } 1697 } 1698 1699 Node *init_trip = phi->in(LoopNode::EntryControl); 1700 1701 // If iv trunc type is smaller than int, check for possible wrap. 1702 if (!TypeInteger::bottom(iv_bt)->higher_equal(iv_trunc_t)) { 1703 assert(trunc1 != nullptr, "must have found some truncation"); 1704 1705 // Get a better type for the phi (filtered thru if's) 1706 const TypeInteger* phi_ft = filtered_type(phi); 1707 1708 // Can iv take on a value that will wrap? 1709 // 1710 // Ensure iv's limit is not within "stride" of the wrap value. 1711 // 1712 // Example for "short" type 1713 // Truncation ensures value is in the range -32768..32767 (iv_trunc_t) 1714 // If the stride is +10, then the last value of the induction 1715 // variable before the increment (phi_ft->_hi) must be 1716 // <= 32767 - 10 and (phi_ft->_lo) must be >= -32768 to 1717 // ensure no truncation occurs after the increment. 1718 1719 if (stride_con > 0) { 1720 if (iv_trunc_t->hi_as_long() - phi_ft->hi_as_long() < stride_con || 1721 iv_trunc_t->lo_as_long() > phi_ft->lo_as_long()) { 1722 return false; // truncation may occur 1723 } 1724 } else if (stride_con < 0) { 1725 if (iv_trunc_t->lo_as_long() - phi_ft->lo_as_long() > stride_con || 1726 iv_trunc_t->hi_as_long() < phi_ft->hi_as_long()) { 1727 return false; // truncation may occur 1728 } 1729 } 1730 // No possibility of wrap so truncation can be discarded 1731 // Promote iv type to Int 1732 } else { 1733 assert(trunc1 == nullptr && trunc2 == nullptr, "no truncation for int"); 1734 } 1735 1736 if (!condition_stride_ok(bt, stride_con)) { 1737 return false; 1738 } 1739 1740 const TypeInteger* init_t = gvn->type(init_trip)->is_integer(iv_bt); 1741 1742 if (stride_con > 0) { 1743 if (init_t->lo_as_long() > max_signed_integer(iv_bt) - stride_con) { 1744 return false; // cyclic loop 1745 } 1746 } else { 1747 if (init_t->hi_as_long() < min_signed_integer(iv_bt) - stride_con) { 1748 return false; // cyclic loop 1749 } 1750 } 1751 1752 if (phi_incr != nullptr && bt != BoolTest::ne) { 1753 // check if there is a possibility of IV overflowing after the first increment 1754 if (stride_con > 0) { 1755 if (init_t->hi_as_long() > max_signed_integer(iv_bt) - stride_con) { 1756 return false; 1757 } 1758 } else { 1759 if (init_t->lo_as_long() < min_signed_integer(iv_bt) - stride_con) { 1760 return false; 1761 } 1762 } 1763 } 1764 1765 // ================================================= 1766 // ---- SUCCESS! Found A Trip-Counted Loop! ----- 1767 // 1768 1769 if (x->Opcode() == Op_Region) { 1770 // x has not yet been transformed to Loop or LongCountedLoop. 1771 // This should only happen if we are inside an infinite loop. 1772 // It happens like this: 1773 // build_loop_tree -> do not attach infinite loop and nested loops 1774 // beautify_loops -> does not transform the infinite and nested loops to LoopNode, because not attached yet 1775 // build_loop_tree -> find and attach infinite and nested loops 1776 // counted_loop -> nested Regions are not yet transformed to LoopNodes, we land here 1777 assert(x->as_Region()->is_in_infinite_subgraph(), 1778 "x can only be a Region and not Loop if inside infinite loop"); 1779 // Come back later when Region is transformed to LoopNode 1780 return false; 1781 } 1782 1783 assert(x->Opcode() == Op_Loop || x->Opcode() == Op_LongCountedLoop, "regular loops only"); 1784 C->print_method(PHASE_BEFORE_CLOOPS, 3); 1785 1786 // =================================================== 1787 // We can only convert this loop to a counted loop if we can guarantee that the iv phi will never overflow at runtime. 1788 // This is an implicit assumption taken by some loop optimizations. We therefore must ensure this property at all cost. 1789 // At this point, we've already excluded some trivial cases where an overflow could have been proven statically. 1790 // But even though we cannot prove that an overflow will *not* happen, we still want to speculatively convert this loop 1791 // to a counted loop. This can be achieved by adding additional iv phi overflow checks before the loop. If they fail, 1792 // we trap and resume execution before the loop without having executed any iteration of the loop, yet. 1793 // 1794 // These additional iv phi overflow checks can be inserted as Loop Limit Check Predicates above the Loop Limit Check 1795 // Parse Predicate which captures a JVM state just before the entry of the loop. If there is no such Parse Predicate, 1796 // we cannot generate a Loop Limit Check Predicate and thus cannot speculatively convert the loop to a counted loop. 1797 // 1798 // In the following, we only focus on int loops with stride > 0 to keep things simple. The argumentation and proof 1799 // for stride < 0 is analogously. For long loops, we would replace max_int with max_long. 1800 // 1801 // 1802 // The loop to be converted does not always need to have the often used shape: 1803 // 1804 // i = init 1805 // i = init loop: 1806 // do { ... 1807 // // ... equivalent i+=stride 1808 // i+=stride <==> if (i < limit) 1809 // } while (i < limit); goto loop 1810 // exit: 1811 // ... 1812 // 1813 // where the loop exit check uses the post-incremented iv phi and a '<'-operator. 1814 // 1815 // We could also have '<='-operator (or '>='-operator for negative strides) or use the pre-incremented iv phi value 1816 // in the loop exit check: 1817 // 1818 // i = init 1819 // loop: 1820 // ... 1821 // if (i <= limit) 1822 // i+=stride 1823 // goto loop 1824 // exit: 1825 // ... 1826 // 1827 // Let's define the following terms: 1828 // - iv_pre_i: The pre-incremented iv phi before the i-th iteration. 1829 // - iv_post_i: The post-incremented iv phi after the i-th iteration. 1830 // 1831 // The iv_pre_i and iv_post_i have the following relation: 1832 // iv_pre_i + stride = iv_post_i 1833 // 1834 // When converting a loop to a counted loop, we want to have a canonicalized loop exit check of the form: 1835 // iv_post_i < adjusted_limit 1836 // 1837 // If that is not the case, we need to canonicalize the loop exit check by using different values for adjusted_limit: 1838 // (LE1) iv_post_i < limit: Already canonicalized. We can directly use limit as adjusted_limit. 1839 // -> adjusted_limit = limit. 1840 // (LE2) iv_post_i <= limit: 1841 // iv_post_i < limit + 1 1842 // -> adjusted limit = limit + 1 1843 // (LE3) iv_pre_i < limit: 1844 // iv_pre_i + stride < limit + stride 1845 // iv_post_i < limit + stride 1846 // -> adjusted_limit = limit + stride 1847 // (LE4) iv_pre_i <= limit: 1848 // iv_pre_i < limit + 1 1849 // iv_pre_i + stride < limit + stride + 1 1850 // iv_post_i < limit + stride + 1 1851 // -> adjusted_limit = limit + stride + 1 1852 // 1853 // Note that: 1854 // (AL) limit <= adjusted_limit. 1855 // 1856 // The following loop invariant has to hold for counted loops with n iterations (i.e. loop exit check true after n-th 1857 // loop iteration) and a canonicalized loop exit check to guarantee that no iv_post_i over- or underflows: 1858 // (INV) For i = 1..n, min_int <= iv_post_i <= max_int 1859 // 1860 // To prove (INV), we require the following two conditions/assumptions: 1861 // (i): adjusted_limit - 1 + stride <= max_int 1862 // (ii): init < limit 1863 // 1864 // If we can prove (INV), we know that there can be no over- or underflow of any iv phi value. We prove (INV) by 1865 // induction by assuming (i) and (ii). 1866 // 1867 // Proof by Induction 1868 // ------------------ 1869 // > Base case (i = 1): We show that (INV) holds after the first iteration: 1870 // min_int <= iv_post_1 = init + stride <= max_int 1871 // Proof: 1872 // First, we note that (ii) implies 1873 // (iii) init <= limit - 1 1874 // max_int >= adjusted_limit - 1 + stride [using (i)] 1875 // >= limit - 1 + stride [using (AL)] 1876 // >= init + stride [using (iii)] 1877 // >= min_int [using stride > 0, no underflow] 1878 // Thus, no overflow happens after the first iteration and (INV) holds for i = 1. 1879 // 1880 // Note that to prove the base case we need (i) and (ii). 1881 // 1882 // > Induction Hypothesis (i = j, j > 1): Assume that (INV) holds after the j-th iteration: 1883 // min_int <= iv_post_j <= max_int 1884 // > Step case (i = j + 1): We show that (INV) also holds after the j+1-th iteration: 1885 // min_int <= iv_post_{j+1} = iv_post_j + stride <= max_int 1886 // Proof: 1887 // If iv_post_j >= adjusted_limit: 1888 // We exit the loop after the j-th iteration, and we don't execute the j+1-th iteration anymore. Thus, there is 1889 // also no iv_{j+1}. Since (INV) holds for iv_j, there is nothing left to prove. 1890 // If iv_post_j < adjusted_limit: 1891 // First, we note that: 1892 // (iv) iv_post_j <= adjusted_limit - 1 1893 // max_int >= adjusted_limit - 1 + stride [using (i)] 1894 // >= iv_post_j + stride [using (iv)] 1895 // >= min_int [using stride > 0, no underflow] 1896 // 1897 // Note that to prove the step case we only need (i). 1898 // 1899 // Thus, by assuming (i) and (ii), we proved (INV). 1900 // 1901 // 1902 // It is therefore enough to add the following two Loop Limit Check Predicates to check assumptions (i) and (ii): 1903 // 1904 // (1) Loop Limit Check Predicate for (i): 1905 // Using (i): adjusted_limit - 1 + stride <= max_int 1906 // 1907 // This condition is now restated to use limit instead of adjusted_limit: 1908 // 1909 // To prevent an overflow of adjusted_limit -1 + stride itself, we rewrite this check to 1910 // max_int - stride + 1 >= adjusted_limit 1911 // We can merge the two constants into 1912 // canonicalized_correction = stride - 1 1913 // which gives us 1914 // max_int - canonicalized_correction >= adjusted_limit 1915 // 1916 // To directly use limit instead of adjusted_limit in the predicate condition, we split adjusted_limit into: 1917 // adjusted_limit = limit + limit_correction 1918 // Since stride > 0 and limit_correction <= stride + 1, we can restate this with no over- or underflow into: 1919 // max_int - canonicalized_correction - limit_correction >= limit 1920 // Since canonicalized_correction and limit_correction are both constants, we can replace them with a new constant: 1921 // final_correction = canonicalized_correction + limit_correction 1922 // which gives us: 1923 // 1924 // Final predicate condition: 1925 // max_int - final_correction >= limit 1926 // 1927 // (2) Loop Limit Check Predicate for (ii): 1928 // Using (ii): init < limit 1929 // 1930 // This Loop Limit Check Predicate is not required if we can prove at compile time that either: 1931 // (2.1) type(init) < type(limit) 1932 // In this case, we know: 1933 // all possible values of init < all possible values of limit 1934 // and we can skip the predicate. 1935 // 1936 // (2.2) init < limit is already checked before (i.e. found as a dominating check) 1937 // In this case, we do not need to re-check the condition and can skip the predicate. 1938 // This is often found for while- and for-loops which have the following shape: 1939 // 1940 // if (init < limit) { // Dominating test. Do not need the Loop Limit Check Predicate below. 1941 // i = init; 1942 // if (init >= limit) { trap(); } // Here we would insert the Loop Limit Check Predicate 1943 // do { 1944 // i += stride; 1945 // } while (i < limit); 1946 // } 1947 // 1948 // (2.3) init + stride <= max_int 1949 // In this case, there is no overflow of the iv phi after the first loop iteration. 1950 // In the proof of the base case above we showed that init + stride <= max_int by using assumption (ii): 1951 // init < limit 1952 // In the proof of the step case above, we did not need (ii) anymore. Therefore, if we already know at 1953 // compile time that init + stride <= max_int then we have trivially proven the base case and that 1954 // there is no overflow of the iv phi after the first iteration. In this case, we don't need to check (ii) 1955 // again and can skip the predicate. 1956 1957 1958 // Accounting for (LE3) and (LE4) where we use pre-incremented phis in the loop exit check. 1959 const jlong limit_correction_for_pre_iv_exit_check = (phi_incr != nullptr) ? stride_con : 0; 1960 1961 // Accounting for (LE2) and (LE4) where we use <= or >= in the loop exit check. 1962 const bool includes_limit = (bt == BoolTest::le || bt == BoolTest::ge); 1963 const jlong limit_correction_for_le_ge_exit_check = (includes_limit ? (stride_con > 0 ? 1 : -1) : 0); 1964 1965 const jlong limit_correction = limit_correction_for_pre_iv_exit_check + limit_correction_for_le_ge_exit_check; 1966 const jlong canonicalized_correction = stride_con + (stride_con > 0 ? -1 : 1); 1967 const jlong final_correction = canonicalized_correction + limit_correction; 1968 1969 int sov = check_stride_overflow(final_correction, limit_t, iv_bt); 1970 Node* init_control = x->in(LoopNode::EntryControl); 1971 1972 // If sov==0, limit's type always satisfies the condition, for 1973 // example, when it is an array length. 1974 if (sov != 0) { 1975 if (sov < 0) { 1976 return false; // Bailout: integer overflow is certain. 1977 } 1978 // (1) Loop Limit Check Predicate is required because we could not statically prove that 1979 // limit + final_correction = adjusted_limit - 1 + stride <= max_int 1980 assert(!x->as_Loop()->is_loop_nest_inner_loop(), "loop was transformed"); 1981 const Predicates predicates(init_control); 1982 const PredicateBlock* loop_limit_check_predicate_block = predicates.loop_limit_check_predicate_block(); 1983 if (!loop_limit_check_predicate_block->has_parse_predicate()) { 1984 // The Loop Limit Check Parse Predicate is not generated if this method trapped here before. 1985 #ifdef ASSERT 1986 if (TraceLoopLimitCheck) { 1987 tty->print("Missing Loop Limit Check Parse Predicate:"); 1988 loop->dump_head(); 1989 x->dump(1); 1990 } 1991 #endif 1992 return false; 1993 } 1994 1995 ParsePredicateNode* loop_limit_check_parse_predicate = loop_limit_check_predicate_block->parse_predicate(); 1996 if (!is_dominator(get_ctrl(limit), loop_limit_check_parse_predicate->in(0))) { 1997 return false; 1998 } 1999 2000 Node* cmp_limit; 2001 Node* bol; 2002 2003 if (stride_con > 0) { 2004 cmp_limit = CmpNode::make(limit, _igvn.integercon(max_signed_integer(iv_bt) - final_correction, iv_bt), iv_bt); 2005 bol = new BoolNode(cmp_limit, BoolTest::le); 2006 } else { 2007 cmp_limit = CmpNode::make(limit, _igvn.integercon(min_signed_integer(iv_bt) - final_correction, iv_bt), iv_bt); 2008 bol = new BoolNode(cmp_limit, BoolTest::ge); 2009 } 2010 2011 insert_loop_limit_check_predicate(init_control->as_IfTrue(), cmp_limit, bol); 2012 } 2013 2014 // (2.3) 2015 const bool init_plus_stride_could_overflow = 2016 (stride_con > 0 && init_t->hi_as_long() > max_signed_integer(iv_bt) - stride_con) || 2017 (stride_con < 0 && init_t->lo_as_long() < min_signed_integer(iv_bt) - stride_con); 2018 // (2.1) 2019 const bool init_gte_limit = (stride_con > 0 && init_t->hi_as_long() >= limit_t->lo_as_long()) || 2020 (stride_con < 0 && init_t->lo_as_long() <= limit_t->hi_as_long()); 2021 2022 if (init_gte_limit && // (2.1) 2023 ((bt == BoolTest::ne || init_plus_stride_could_overflow) && // (2.3) 2024 !has_dominating_loop_limit_check(init_trip, limit, stride_con, iv_bt, init_control))) { // (2.2) 2025 // (2) Iteration Loop Limit Check Predicate is required because neither (2.1), (2.2), nor (2.3) holds. 2026 // We use the following condition: 2027 // - stride > 0: init < limit 2028 // - stride < 0: init > limit 2029 // 2030 // This predicate is always required if we have a non-equal-operator in the loop exit check (where stride = 1 is 2031 // a requirement). We transform the loop exit check by using a less-than-operator. By doing so, we must always 2032 // check that init < limit. Otherwise, we could have a different number of iterations at runtime. 2033 2034 const Predicates predicates(init_control); 2035 const PredicateBlock* loop_limit_check_predicate_block = predicates.loop_limit_check_predicate_block(); 2036 if (!loop_limit_check_predicate_block->has_parse_predicate()) { 2037 // The Loop Limit Check Parse Predicate is not generated if this method trapped here before. 2038 #ifdef ASSERT 2039 if (TraceLoopLimitCheck) { 2040 tty->print("Missing Loop Limit Check Parse Predicate:"); 2041 loop->dump_head(); 2042 x->dump(1); 2043 } 2044 #endif 2045 return false; 2046 } 2047 2048 ParsePredicateNode* loop_limit_check_parse_predicate = loop_limit_check_predicate_block->parse_predicate(); 2049 Node* parse_predicate_entry = loop_limit_check_parse_predicate->in(0); 2050 if (!is_dominator(get_ctrl(limit), parse_predicate_entry) || 2051 !is_dominator(get_ctrl(init_trip), parse_predicate_entry)) { 2052 return false; 2053 } 2054 2055 Node* cmp_limit; 2056 Node* bol; 2057 2058 if (stride_con > 0) { 2059 cmp_limit = CmpNode::make(init_trip, limit, iv_bt); 2060 bol = new BoolNode(cmp_limit, BoolTest::lt); 2061 } else { 2062 cmp_limit = CmpNode::make(init_trip, limit, iv_bt); 2063 bol = new BoolNode(cmp_limit, BoolTest::gt); 2064 } 2065 2066 insert_loop_limit_check_predicate(init_control->as_IfTrue(), cmp_limit, bol); 2067 } 2068 2069 if (bt == BoolTest::ne) { 2070 // Now we need to canonicalize the loop condition if it is 'ne'. 2071 assert(stride_con == 1 || stride_con == -1, "simple increment only - checked before"); 2072 if (stride_con > 0) { 2073 // 'ne' can be replaced with 'lt' only when init < limit. This is ensured by the inserted predicate above. 2074 bt = BoolTest::lt; 2075 } else { 2076 assert(stride_con < 0, "must be"); 2077 // 'ne' can be replaced with 'gt' only when init > limit. This is ensured by the inserted predicate above. 2078 bt = BoolTest::gt; 2079 } 2080 } 2081 2082 Node* sfpt = nullptr; 2083 if (loop->_child == nullptr) { 2084 sfpt = find_safepoint(back_control, x, loop); 2085 } else { 2086 sfpt = iff->in(0); 2087 if (sfpt->Opcode() != Op_SafePoint) { 2088 sfpt = nullptr; 2089 } 2090 } 2091 2092 if (x->in(LoopNode::LoopBackControl)->Opcode() == Op_SafePoint) { 2093 Node* backedge_sfpt = x->in(LoopNode::LoopBackControl); 2094 if (((iv_bt == T_INT && LoopStripMiningIter != 0) || 2095 iv_bt == T_LONG) && 2096 sfpt == nullptr) { 2097 // Leaving the safepoint on the backedge and creating a 2098 // CountedLoop will confuse optimizations. We can't move the 2099 // safepoint around because its jvm state wouldn't match a new 2100 // location. Give up on that loop. 2101 return false; 2102 } 2103 if (is_deleteable_safept(backedge_sfpt)) { 2104 lazy_replace(backedge_sfpt, iftrue); 2105 if (loop->_safepts != nullptr) { 2106 loop->_safepts->yank(backedge_sfpt); 2107 } 2108 loop->_tail = iftrue; 2109 } 2110 } 2111 2112 2113 #ifdef ASSERT 2114 if (iv_bt == T_INT && 2115 !x->as_Loop()->is_loop_nest_inner_loop() && 2116 StressLongCountedLoop > 0 && 2117 trunc1 == nullptr && 2118 convert_to_long_loop(cmp, phi, loop)) { 2119 return false; 2120 } 2121 #endif 2122 2123 Node* adjusted_limit = limit; 2124 if (phi_incr != nullptr) { 2125 // If compare points directly to the phi we need to adjust 2126 // the compare so that it points to the incr. Limit have 2127 // to be adjusted to keep trip count the same and we 2128 // should avoid int overflow. 2129 // 2130 // i = init; do {} while(i++ < limit); 2131 // is converted to 2132 // i = init; do {} while(++i < limit+1); 2133 // 2134 adjusted_limit = gvn->transform(AddNode::make(limit, stride, iv_bt)); 2135 } 2136 2137 if (includes_limit) { 2138 // The limit check guaranties that 'limit <= (max_jint - stride)' so 2139 // we can convert 'i <= limit' to 'i < limit+1' since stride != 0. 2140 // 2141 Node* one = (stride_con > 0) ? gvn->integercon( 1, iv_bt) : gvn->integercon(-1, iv_bt); 2142 adjusted_limit = gvn->transform(AddNode::make(adjusted_limit, one, iv_bt)); 2143 if (bt == BoolTest::le) 2144 bt = BoolTest::lt; 2145 else if (bt == BoolTest::ge) 2146 bt = BoolTest::gt; 2147 else 2148 ShouldNotReachHere(); 2149 } 2150 set_subtree_ctrl(adjusted_limit, false); 2151 2152 // Build a canonical trip test. 2153 // Clone code, as old values may be in use. 2154 incr = incr->clone(); 2155 incr->set_req(1,phi); 2156 incr->set_req(2,stride); 2157 incr = _igvn.register_new_node_with_optimizer(incr); 2158 set_early_ctrl(incr, false); 2159 _igvn.rehash_node_delayed(phi); 2160 phi->set_req_X( LoopNode::LoopBackControl, incr, &_igvn ); 2161 2162 // If phi type is more restrictive than Int, raise to 2163 // Int to prevent (almost) infinite recursion in igvn 2164 // which can only handle integer types for constants or minint..maxint. 2165 if (!TypeInteger::bottom(iv_bt)->higher_equal(phi->bottom_type())) { 2166 Node* nphi = PhiNode::make(phi->in(0), phi->in(LoopNode::EntryControl), TypeInteger::bottom(iv_bt)); 2167 nphi->set_req(LoopNode::LoopBackControl, phi->in(LoopNode::LoopBackControl)); 2168 nphi = _igvn.register_new_node_with_optimizer(nphi); 2169 set_ctrl(nphi, get_ctrl(phi)); 2170 _igvn.replace_node(phi, nphi); 2171 phi = nphi->as_Phi(); 2172 } 2173 cmp = cmp->clone(); 2174 cmp->set_req(1,incr); 2175 cmp->set_req(2, adjusted_limit); 2176 cmp = _igvn.register_new_node_with_optimizer(cmp); 2177 set_ctrl(cmp, iff->in(0)); 2178 2179 test = test->clone()->as_Bool(); 2180 (*(BoolTest*)&test->_test)._test = bt; 2181 test->set_req(1,cmp); 2182 _igvn.register_new_node_with_optimizer(test); 2183 set_ctrl(test, iff->in(0)); 2184 2185 // Replace the old IfNode with a new LoopEndNode 2186 Node *lex = _igvn.register_new_node_with_optimizer(BaseCountedLoopEndNode::make(iff->in(0), test, cl_prob, iff->as_If()->_fcnt, iv_bt)); 2187 IfNode *le = lex->as_If(); 2188 uint dd = dom_depth(iff); 2189 set_idom(le, le->in(0), dd); // Update dominance for loop exit 2190 set_loop(le, loop); 2191 2192 // Get the loop-exit control 2193 Node *iffalse = iff->as_If()->proj_out(!(iftrue_op == Op_IfTrue)); 2194 2195 // Need to swap loop-exit and loop-back control? 2196 if (iftrue_op == Op_IfFalse) { 2197 Node *ift2=_igvn.register_new_node_with_optimizer(new IfTrueNode (le)); 2198 Node *iff2=_igvn.register_new_node_with_optimizer(new IfFalseNode(le)); 2199 2200 loop->_tail = back_control = ift2; 2201 set_loop(ift2, loop); 2202 set_loop(iff2, get_loop(iffalse)); 2203 2204 // Lazy update of 'get_ctrl' mechanism. 2205 lazy_replace(iffalse, iff2); 2206 lazy_replace(iftrue, ift2); 2207 2208 // Swap names 2209 iffalse = iff2; 2210 iftrue = ift2; 2211 } else { 2212 _igvn.rehash_node_delayed(iffalse); 2213 _igvn.rehash_node_delayed(iftrue); 2214 iffalse->set_req_X( 0, le, &_igvn ); 2215 iftrue ->set_req_X( 0, le, &_igvn ); 2216 } 2217 2218 set_idom(iftrue, le, dd+1); 2219 set_idom(iffalse, le, dd+1); 2220 assert(iff->outcnt() == 0, "should be dead now"); 2221 lazy_replace( iff, le ); // fix 'get_ctrl' 2222 2223 Node* entry_control = init_control; 2224 bool strip_mine_loop = iv_bt == T_INT && 2225 loop->_child == nullptr && 2226 sfpt != nullptr && 2227 !loop->_has_call && 2228 is_deleteable_safept(sfpt); 2229 IdealLoopTree* outer_ilt = nullptr; 2230 if (strip_mine_loop) { 2231 outer_ilt = create_outer_strip_mined_loop(test, cmp, init_control, loop, 2232 cl_prob, le->_fcnt, entry_control, 2233 iffalse); 2234 } 2235 2236 // Now setup a new CountedLoopNode to replace the existing LoopNode 2237 BaseCountedLoopNode *l = BaseCountedLoopNode::make(entry_control, back_control, iv_bt); 2238 l->set_unswitch_count(x->as_Loop()->unswitch_count()); // Preserve 2239 // The following assert is approximately true, and defines the intention 2240 // of can_be_counted_loop. It fails, however, because phase->type 2241 // is not yet initialized for this loop and its parts. 2242 //assert(l->can_be_counted_loop(this), "sanity"); 2243 _igvn.register_new_node_with_optimizer(l); 2244 set_loop(l, loop); 2245 loop->_head = l; 2246 // Fix all data nodes placed at the old loop head. 2247 // Uses the lazy-update mechanism of 'get_ctrl'. 2248 lazy_replace( x, l ); 2249 set_idom(l, entry_control, dom_depth(entry_control) + 1); 2250 2251 if (iv_bt == T_INT && (LoopStripMiningIter == 0 || strip_mine_loop)) { 2252 // Check for immediately preceding SafePoint and remove 2253 if (sfpt != nullptr && (strip_mine_loop || is_deleteable_safept(sfpt))) { 2254 if (strip_mine_loop) { 2255 Node* outer_le = outer_ilt->_tail->in(0); 2256 Node* sfpt_clone = sfpt->clone(); 2257 sfpt_clone->set_req(0, iffalse); 2258 outer_le->set_req(0, sfpt_clone); 2259 2260 Node* polladdr = sfpt_clone->in(TypeFunc::Parms); 2261 if (polladdr != nullptr && polladdr->is_Load()) { 2262 // Polling load should be pinned outside inner loop. 2263 Node* new_polladdr = polladdr->clone(); 2264 new_polladdr->set_req(0, iffalse); 2265 _igvn.register_new_node_with_optimizer(new_polladdr, polladdr); 2266 set_ctrl(new_polladdr, iffalse); 2267 sfpt_clone->set_req(TypeFunc::Parms, new_polladdr); 2268 } 2269 // When this code runs, loop bodies have not yet been populated. 2270 const bool body_populated = false; 2271 register_control(sfpt_clone, outer_ilt, iffalse, body_populated); 2272 set_idom(outer_le, sfpt_clone, dom_depth(sfpt_clone)); 2273 } 2274 lazy_replace(sfpt, sfpt->in(TypeFunc::Control)); 2275 if (loop->_safepts != nullptr) { 2276 loop->_safepts->yank(sfpt); 2277 } 2278 } 2279 } 2280 2281 #ifdef ASSERT 2282 assert(l->is_valid_counted_loop(iv_bt), "counted loop shape is messed up"); 2283 assert(l == loop->_head && l->phi() == phi && l->loopexit_or_null() == lex, "" ); 2284 #endif 2285 #ifndef PRODUCT 2286 if (TraceLoopOpts) { 2287 tty->print("Counted "); 2288 loop->dump_head(); 2289 } 2290 #endif 2291 2292 C->print_method(PHASE_AFTER_CLOOPS, 3); 2293 2294 // Capture bounds of the loop in the induction variable Phi before 2295 // subsequent transformation (iteration splitting) obscures the 2296 // bounds 2297 l->phi()->as_Phi()->set_type(l->phi()->Value(&_igvn)); 2298 2299 if (strip_mine_loop) { 2300 l->mark_strip_mined(); 2301 l->verify_strip_mined(1); 2302 outer_ilt->_head->as_Loop()->verify_strip_mined(1); 2303 loop = outer_ilt; 2304 } 2305 2306 #ifndef PRODUCT 2307 if (x->as_Loop()->is_loop_nest_inner_loop() && iv_bt == T_LONG) { 2308 Atomic::inc(&_long_loop_counted_loops); 2309 } 2310 #endif 2311 if (iv_bt == T_LONG && x->as_Loop()->is_loop_nest_outer_loop()) { 2312 l->mark_loop_nest_outer_loop(); 2313 } 2314 2315 return true; 2316 } 2317 2318 // Check if there is a dominating loop limit check of the form 'init < limit' starting at the loop entry. 2319 // If there is one, then we do not need to create an additional Loop Limit Check Predicate. 2320 bool PhaseIdealLoop::has_dominating_loop_limit_check(Node* init_trip, Node* limit, const jlong stride_con, 2321 const BasicType iv_bt, Node* loop_entry) { 2322 // Eagerly call transform() on the Cmp and Bool node to common them up if possible. This is required in order to 2323 // successfully find a dominated test with the If node below. 2324 Node* cmp_limit; 2325 Node* bol; 2326 if (stride_con > 0) { 2327 cmp_limit = _igvn.transform(CmpNode::make(init_trip, limit, iv_bt)); 2328 bol = _igvn.transform(new BoolNode(cmp_limit, BoolTest::lt)); 2329 } else { 2330 cmp_limit = _igvn.transform(CmpNode::make(init_trip, limit, iv_bt)); 2331 bol = _igvn.transform(new BoolNode(cmp_limit, BoolTest::gt)); 2332 } 2333 2334 // Check if there is already a dominating init < limit check. If so, we do not need a Loop Limit Check Predicate. 2335 IfNode* iff = new IfNode(loop_entry, bol, PROB_MIN, COUNT_UNKNOWN); 2336 // Also add fake IfProj nodes in order to call transform() on the newly created IfNode. 2337 IfFalseNode* if_false = new IfFalseNode(iff); 2338 IfTrueNode* if_true = new IfTrueNode(iff); 2339 Node* dominated_iff = _igvn.transform(iff); 2340 // ConI node? Found dominating test (IfNode::dominated_by() returns a ConI node). 2341 const bool found_dominating_test = dominated_iff != nullptr && dominated_iff->is_ConI(); 2342 2343 // Kill the If with its projections again in the next IGVN round by cutting it off from the graph. 2344 _igvn.replace_input_of(iff, 0, C->top()); 2345 _igvn.replace_input_of(iff, 1, C->top()); 2346 return found_dominating_test; 2347 } 2348 2349 //----------------------exact_limit------------------------------------------- 2350 Node* PhaseIdealLoop::exact_limit( IdealLoopTree *loop ) { 2351 assert(loop->_head->is_CountedLoop(), ""); 2352 CountedLoopNode *cl = loop->_head->as_CountedLoop(); 2353 assert(cl->is_valid_counted_loop(T_INT), ""); 2354 2355 if (cl->stride_con() == 1 || 2356 cl->stride_con() == -1 || 2357 cl->limit()->Opcode() == Op_LoopLimit) { 2358 // Old code has exact limit (it could be incorrect in case of int overflow). 2359 // Loop limit is exact with stride == 1. And loop may already have exact limit. 2360 return cl->limit(); 2361 } 2362 Node *limit = nullptr; 2363 #ifdef ASSERT 2364 BoolTest::mask bt = cl->loopexit()->test_trip(); 2365 assert(bt == BoolTest::lt || bt == BoolTest::gt, "canonical test is expected"); 2366 #endif 2367 if (cl->has_exact_trip_count()) { 2368 // Simple case: loop has constant boundaries. 2369 // Use jlongs to avoid integer overflow. 2370 int stride_con = cl->stride_con(); 2371 jlong init_con = cl->init_trip()->get_int(); 2372 jlong limit_con = cl->limit()->get_int(); 2373 julong trip_cnt = cl->trip_count(); 2374 jlong final_con = init_con + trip_cnt*stride_con; 2375 int final_int = (int)final_con; 2376 // The final value should be in integer range since the loop 2377 // is counted and the limit was checked for overflow. 2378 assert(final_con == (jlong)final_int, "final value should be integer"); 2379 limit = _igvn.intcon(final_int); 2380 } else { 2381 // Create new LoopLimit node to get exact limit (final iv value). 2382 limit = new LoopLimitNode(C, cl->init_trip(), cl->limit(), cl->stride()); 2383 register_new_node(limit, cl->in(LoopNode::EntryControl)); 2384 } 2385 assert(limit != nullptr, "sanity"); 2386 return limit; 2387 } 2388 2389 //------------------------------Ideal------------------------------------------ 2390 // Return a node which is more "ideal" than the current node. 2391 // Attempt to convert into a counted-loop. 2392 Node *LoopNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2393 if (!can_be_counted_loop(phase) && !is_OuterStripMinedLoop()) { 2394 phase->C->set_major_progress(); 2395 } 2396 return RegionNode::Ideal(phase, can_reshape); 2397 } 2398 2399 #ifdef ASSERT 2400 void LoopNode::verify_strip_mined(int expect_skeleton) const { 2401 const OuterStripMinedLoopNode* outer = nullptr; 2402 const CountedLoopNode* inner = nullptr; 2403 if (is_strip_mined()) { 2404 if (!is_valid_counted_loop(T_INT)) { 2405 return; // Skip malformed counted loop 2406 } 2407 assert(is_CountedLoop(), "no Loop should be marked strip mined"); 2408 inner = as_CountedLoop(); 2409 outer = inner->in(LoopNode::EntryControl)->as_OuterStripMinedLoop(); 2410 } else if (is_OuterStripMinedLoop()) { 2411 outer = this->as_OuterStripMinedLoop(); 2412 inner = outer->unique_ctrl_out()->as_CountedLoop(); 2413 assert(inner->is_valid_counted_loop(T_INT) && inner->is_strip_mined(), "OuterStripMinedLoop should have been removed"); 2414 assert(!is_strip_mined(), "outer loop shouldn't be marked strip mined"); 2415 } 2416 if (inner != nullptr || outer != nullptr) { 2417 assert(inner != nullptr && outer != nullptr, "missing loop in strip mined nest"); 2418 Node* outer_tail = outer->in(LoopNode::LoopBackControl); 2419 Node* outer_le = outer_tail->in(0); 2420 assert(outer_le->Opcode() == Op_OuterStripMinedLoopEnd, "tail of outer loop should be an If"); 2421 Node* sfpt = outer_le->in(0); 2422 assert(sfpt->Opcode() == Op_SafePoint, "where's the safepoint?"); 2423 Node* inner_out = sfpt->in(0); 2424 CountedLoopEndNode* cle = inner_out->in(0)->as_CountedLoopEnd(); 2425 assert(cle == inner->loopexit_or_null(), "mismatch"); 2426 bool has_skeleton = outer_le->in(1)->bottom_type()->singleton() && outer_le->in(1)->bottom_type()->is_int()->get_con() == 0; 2427 if (has_skeleton) { 2428 assert(expect_skeleton == 1 || expect_skeleton == -1, "unexpected skeleton node"); 2429 assert(outer->outcnt() == 2, "only control nodes"); 2430 } else { 2431 assert(expect_skeleton == 0 || expect_skeleton == -1, "no skeleton node?"); 2432 uint phis = 0; 2433 uint be_loads = 0; 2434 Node* be = inner->in(LoopNode::LoopBackControl); 2435 for (DUIterator_Fast imax, i = inner->fast_outs(imax); i < imax; i++) { 2436 Node* u = inner->fast_out(i); 2437 if (u->is_Phi()) { 2438 phis++; 2439 for (DUIterator_Fast jmax, j = be->fast_outs(jmax); j < jmax; j++) { 2440 Node* n = be->fast_out(j); 2441 if (n->is_Load()) { 2442 assert(n->in(0) == be || n->find_prec_edge(be) > 0, "should be on the backedge"); 2443 do { 2444 n = n->raw_out(0); 2445 } while (!n->is_Phi()); 2446 if (n == u) { 2447 be_loads++; 2448 break; 2449 } 2450 } 2451 } 2452 } 2453 } 2454 assert(be_loads <= phis, "wrong number phis that depends on a pinned load"); 2455 for (DUIterator_Fast imax, i = outer->fast_outs(imax); i < imax; i++) { 2456 Node* u = outer->fast_out(i); 2457 assert(u == outer || u == inner || u->is_Phi(), "nothing between inner and outer loop"); 2458 } 2459 uint stores = 0; 2460 for (DUIterator_Fast imax, i = inner_out->fast_outs(imax); i < imax; i++) { 2461 Node* u = inner_out->fast_out(i); 2462 if (u->is_Store()) { 2463 stores++; 2464 } 2465 } 2466 // Late optimization of loads on backedge can cause Phi of outer loop to be eliminated but Phi of inner loop is 2467 // not guaranteed to be optimized out. 2468 assert(outer->outcnt() >= phis + 2 - be_loads && outer->outcnt() <= phis + 2 + stores + 1, "only phis"); 2469 } 2470 assert(sfpt->outcnt() == 1, "no data node"); 2471 assert(outer_tail->outcnt() == 1 || !has_skeleton, "no data node"); 2472 } 2473 } 2474 #endif 2475 2476 //============================================================================= 2477 //------------------------------Ideal------------------------------------------ 2478 // Return a node which is more "ideal" than the current node. 2479 // Attempt to convert into a counted-loop. 2480 Node *CountedLoopNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2481 return RegionNode::Ideal(phase, can_reshape); 2482 } 2483 2484 //------------------------------dump_spec-------------------------------------- 2485 // Dump special per-node info 2486 #ifndef PRODUCT 2487 void CountedLoopNode::dump_spec(outputStream *st) const { 2488 LoopNode::dump_spec(st); 2489 if (stride_is_con()) { 2490 st->print("stride: %d ",stride_con()); 2491 } 2492 if (is_pre_loop ()) st->print("pre of N%d" , _main_idx); 2493 if (is_main_loop()) st->print("main of N%d", _idx); 2494 if (is_post_loop()) st->print("post of N%d", _main_idx); 2495 if (is_strip_mined()) st->print(" strip mined"); 2496 } 2497 #endif 2498 2499 //============================================================================= 2500 jlong BaseCountedLoopEndNode::stride_con() const { 2501 return stride()->bottom_type()->is_integer(bt())->get_con_as_long(bt()); 2502 } 2503 2504 2505 BaseCountedLoopEndNode* BaseCountedLoopEndNode::make(Node* control, Node* test, float prob, float cnt, BasicType bt) { 2506 if (bt == T_INT) { 2507 return new CountedLoopEndNode(control, test, prob, cnt); 2508 } 2509 assert(bt == T_LONG, "unsupported"); 2510 return new LongCountedLoopEndNode(control, test, prob, cnt); 2511 } 2512 2513 //============================================================================= 2514 //------------------------------Value----------------------------------------- 2515 const Type* LoopLimitNode::Value(PhaseGVN* phase) const { 2516 const Type* init_t = phase->type(in(Init)); 2517 const Type* limit_t = phase->type(in(Limit)); 2518 const Type* stride_t = phase->type(in(Stride)); 2519 // Either input is TOP ==> the result is TOP 2520 if (init_t == Type::TOP) return Type::TOP; 2521 if (limit_t == Type::TOP) return Type::TOP; 2522 if (stride_t == Type::TOP) return Type::TOP; 2523 2524 int stride_con = stride_t->is_int()->get_con(); 2525 if (stride_con == 1) 2526 return bottom_type(); // Identity 2527 2528 if (init_t->is_int()->is_con() && limit_t->is_int()->is_con()) { 2529 // Use jlongs to avoid integer overflow. 2530 jlong init_con = init_t->is_int()->get_con(); 2531 jlong limit_con = limit_t->is_int()->get_con(); 2532 int stride_m = stride_con - (stride_con > 0 ? 1 : -1); 2533 jlong trip_count = (limit_con - init_con + stride_m)/stride_con; 2534 jlong final_con = init_con + stride_con*trip_count; 2535 int final_int = (int)final_con; 2536 // The final value should be in integer range since the loop 2537 // is counted and the limit was checked for overflow. 2538 // Assert checks for overflow only if all input nodes are ConINodes, as during CCP 2539 // there might be a temporary overflow from PhiNodes see JDK-8309266 2540 assert((in(Init)->is_ConI() && in(Limit)->is_ConI() && in(Stride)->is_ConI()) ? final_con == (jlong)final_int : true, "final value should be integer"); 2541 if (final_con == (jlong)final_int) { 2542 return TypeInt::make(final_int); 2543 } else { 2544 return bottom_type(); 2545 } 2546 } 2547 2548 return bottom_type(); // TypeInt::INT 2549 } 2550 2551 //------------------------------Ideal------------------------------------------ 2552 // Return a node which is more "ideal" than the current node. 2553 Node *LoopLimitNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2554 if (phase->type(in(Init)) == Type::TOP || 2555 phase->type(in(Limit)) == Type::TOP || 2556 phase->type(in(Stride)) == Type::TOP) 2557 return nullptr; // Dead 2558 2559 int stride_con = phase->type(in(Stride))->is_int()->get_con(); 2560 if (stride_con == 1) 2561 return nullptr; // Identity 2562 2563 if (in(Init)->is_Con() && in(Limit)->is_Con()) 2564 return nullptr; // Value 2565 2566 // Delay following optimizations until all loop optimizations 2567 // done to keep Ideal graph simple. 2568 if (!can_reshape || !phase->C->post_loop_opts_phase()) { 2569 return nullptr; 2570 } 2571 2572 const TypeInt* init_t = phase->type(in(Init) )->is_int(); 2573 const TypeInt* limit_t = phase->type(in(Limit))->is_int(); 2574 int stride_p; 2575 jlong lim, ini; 2576 julong max; 2577 if (stride_con > 0) { 2578 stride_p = stride_con; 2579 lim = limit_t->_hi; 2580 ini = init_t->_lo; 2581 max = (julong)max_jint; 2582 } else { 2583 stride_p = -stride_con; 2584 lim = init_t->_hi; 2585 ini = limit_t->_lo; 2586 max = (julong)min_jint; 2587 } 2588 julong range = lim - ini + stride_p; 2589 if (range <= max) { 2590 // Convert to integer expression if it is not overflow. 2591 Node* stride_m = phase->intcon(stride_con - (stride_con > 0 ? 1 : -1)); 2592 Node *range = phase->transform(new SubINode(in(Limit), in(Init))); 2593 Node *bias = phase->transform(new AddINode(range, stride_m)); 2594 Node *trip = phase->transform(new DivINode(0, bias, in(Stride))); 2595 Node *span = phase->transform(new MulINode(trip, in(Stride))); 2596 return new AddINode(span, in(Init)); // exact limit 2597 } 2598 2599 if (is_power_of_2(stride_p) || // divisor is 2^n 2600 !Matcher::has_match_rule(Op_LoopLimit)) { // or no specialized Mach node? 2601 // Convert to long expression to avoid integer overflow 2602 // and let igvn optimizer convert this division. 2603 // 2604 Node* init = phase->transform( new ConvI2LNode(in(Init))); 2605 Node* limit = phase->transform( new ConvI2LNode(in(Limit))); 2606 Node* stride = phase->longcon(stride_con); 2607 Node* stride_m = phase->longcon(stride_con - (stride_con > 0 ? 1 : -1)); 2608 2609 Node *range = phase->transform(new SubLNode(limit, init)); 2610 Node *bias = phase->transform(new AddLNode(range, stride_m)); 2611 Node *span; 2612 if (stride_con > 0 && is_power_of_2(stride_p)) { 2613 // bias >= 0 if stride >0, so if stride is 2^n we can use &(-stride) 2614 // and avoid generating rounding for division. Zero trip guard should 2615 // guarantee that init < limit but sometimes the guard is missing and 2616 // we can get situation when init > limit. Note, for the empty loop 2617 // optimization zero trip guard is generated explicitly which leaves 2618 // only RCE predicate where exact limit is used and the predicate 2619 // will simply fail forcing recompilation. 2620 Node* neg_stride = phase->longcon(-stride_con); 2621 span = phase->transform(new AndLNode(bias, neg_stride)); 2622 } else { 2623 Node *trip = phase->transform(new DivLNode(0, bias, stride)); 2624 span = phase->transform(new MulLNode(trip, stride)); 2625 } 2626 // Convert back to int 2627 Node *span_int = phase->transform(new ConvL2INode(span)); 2628 return new AddINode(span_int, in(Init)); // exact limit 2629 } 2630 2631 return nullptr; // No progress 2632 } 2633 2634 //------------------------------Identity--------------------------------------- 2635 // If stride == 1 return limit node. 2636 Node* LoopLimitNode::Identity(PhaseGVN* phase) { 2637 int stride_con = phase->type(in(Stride))->is_int()->get_con(); 2638 if (stride_con == 1 || stride_con == -1) 2639 return in(Limit); 2640 return this; 2641 } 2642 2643 //============================================================================= 2644 //----------------------match_incr_with_optional_truncation-------------------- 2645 // Match increment with optional truncation: 2646 // CHAR: (i+1)&0x7fff, BYTE: ((i+1)<<8)>>8, or SHORT: ((i+1)<<16)>>16 2647 // Return null for failure. Success returns the increment node. 2648 Node* CountedLoopNode::match_incr_with_optional_truncation(Node* expr, Node** trunc1, Node** trunc2, 2649 const TypeInteger** trunc_type, 2650 BasicType bt) { 2651 // Quick cutouts: 2652 if (expr == nullptr || expr->req() != 3) return nullptr; 2653 2654 Node *t1 = nullptr; 2655 Node *t2 = nullptr; 2656 Node* n1 = expr; 2657 int n1op = n1->Opcode(); 2658 const TypeInteger* trunc_t = TypeInteger::bottom(bt); 2659 2660 if (bt == T_INT) { 2661 // Try to strip (n1 & M) or (n1 << N >> N) from n1. 2662 if (n1op == Op_AndI && 2663 n1->in(2)->is_Con() && 2664 n1->in(2)->bottom_type()->is_int()->get_con() == 0x7fff) { 2665 // %%% This check should match any mask of 2**K-1. 2666 t1 = n1; 2667 n1 = t1->in(1); 2668 n1op = n1->Opcode(); 2669 trunc_t = TypeInt::CHAR; 2670 } else if (n1op == Op_RShiftI && 2671 n1->in(1) != nullptr && 2672 n1->in(1)->Opcode() == Op_LShiftI && 2673 n1->in(2) == n1->in(1)->in(2) && 2674 n1->in(2)->is_Con()) { 2675 jint shift = n1->in(2)->bottom_type()->is_int()->get_con(); 2676 // %%% This check should match any shift in [1..31]. 2677 if (shift == 16 || shift == 8) { 2678 t1 = n1; 2679 t2 = t1->in(1); 2680 n1 = t2->in(1); 2681 n1op = n1->Opcode(); 2682 if (shift == 16) { 2683 trunc_t = TypeInt::SHORT; 2684 } else if (shift == 8) { 2685 trunc_t = TypeInt::BYTE; 2686 } 2687 } 2688 } 2689 } 2690 2691 // If (maybe after stripping) it is an AddI, we won: 2692 if (n1op == Op_Add(bt)) { 2693 *trunc1 = t1; 2694 *trunc2 = t2; 2695 *trunc_type = trunc_t; 2696 return n1; 2697 } 2698 2699 // failed 2700 return nullptr; 2701 } 2702 2703 LoopNode* CountedLoopNode::skip_strip_mined(int expect_skeleton) { 2704 if (is_strip_mined() && in(EntryControl) != nullptr && in(EntryControl)->is_OuterStripMinedLoop()) { 2705 verify_strip_mined(expect_skeleton); 2706 return in(EntryControl)->as_Loop(); 2707 } 2708 return this; 2709 } 2710 2711 OuterStripMinedLoopNode* CountedLoopNode::outer_loop() const { 2712 assert(is_strip_mined(), "not a strip mined loop"); 2713 Node* c = in(EntryControl); 2714 if (c == nullptr || c->is_top() || !c->is_OuterStripMinedLoop()) { 2715 return nullptr; 2716 } 2717 return c->as_OuterStripMinedLoop(); 2718 } 2719 2720 IfTrueNode* OuterStripMinedLoopNode::outer_loop_tail() const { 2721 Node* c = in(LoopBackControl); 2722 if (c == nullptr || c->is_top()) { 2723 return nullptr; 2724 } 2725 return c->as_IfTrue(); 2726 } 2727 2728 IfTrueNode* CountedLoopNode::outer_loop_tail() const { 2729 LoopNode* l = outer_loop(); 2730 if (l == nullptr) { 2731 return nullptr; 2732 } 2733 return l->outer_loop_tail(); 2734 } 2735 2736 OuterStripMinedLoopEndNode* OuterStripMinedLoopNode::outer_loop_end() const { 2737 IfTrueNode* proj = outer_loop_tail(); 2738 if (proj == nullptr) { 2739 return nullptr; 2740 } 2741 Node* c = proj->in(0); 2742 if (c == nullptr || c->is_top() || c->outcnt() != 2) { 2743 return nullptr; 2744 } 2745 return c->as_OuterStripMinedLoopEnd(); 2746 } 2747 2748 OuterStripMinedLoopEndNode* CountedLoopNode::outer_loop_end() const { 2749 LoopNode* l = outer_loop(); 2750 if (l == nullptr) { 2751 return nullptr; 2752 } 2753 return l->outer_loop_end(); 2754 } 2755 2756 IfFalseNode* OuterStripMinedLoopNode::outer_loop_exit() const { 2757 IfNode* le = outer_loop_end(); 2758 if (le == nullptr) { 2759 return nullptr; 2760 } 2761 Node* c = le->proj_out_or_null(false); 2762 if (c == nullptr) { 2763 return nullptr; 2764 } 2765 return c->as_IfFalse(); 2766 } 2767 2768 IfFalseNode* CountedLoopNode::outer_loop_exit() const { 2769 LoopNode* l = outer_loop(); 2770 if (l == nullptr) { 2771 return nullptr; 2772 } 2773 return l->outer_loop_exit(); 2774 } 2775 2776 SafePointNode* OuterStripMinedLoopNode::outer_safepoint() const { 2777 IfNode* le = outer_loop_end(); 2778 if (le == nullptr) { 2779 return nullptr; 2780 } 2781 Node* c = le->in(0); 2782 if (c == nullptr || c->is_top()) { 2783 return nullptr; 2784 } 2785 assert(c->Opcode() == Op_SafePoint, "broken outer loop"); 2786 return c->as_SafePoint(); 2787 } 2788 2789 SafePointNode* CountedLoopNode::outer_safepoint() const { 2790 LoopNode* l = outer_loop(); 2791 if (l == nullptr) { 2792 return nullptr; 2793 } 2794 return l->outer_safepoint(); 2795 } 2796 2797 Node* CountedLoopNode::skip_assertion_predicates_with_halt() { 2798 Node* ctrl = in(LoopNode::EntryControl); 2799 if (is_main_loop()) { 2800 ctrl = skip_strip_mined()->in(LoopNode::EntryControl); 2801 } 2802 if (is_main_loop() || is_post_loop()) { 2803 AssertionPredicatesWithHalt assertion_predicates(ctrl); 2804 return assertion_predicates.entry(); 2805 } 2806 return ctrl; 2807 } 2808 2809 2810 int CountedLoopNode::stride_con() const { 2811 CountedLoopEndNode* cle = loopexit_or_null(); 2812 return cle != nullptr ? cle->stride_con() : 0; 2813 } 2814 2815 BaseCountedLoopNode* BaseCountedLoopNode::make(Node* entry, Node* backedge, BasicType bt) { 2816 if (bt == T_INT) { 2817 return new CountedLoopNode(entry, backedge); 2818 } 2819 assert(bt == T_LONG, "unsupported"); 2820 return new LongCountedLoopNode(entry, backedge); 2821 } 2822 2823 void OuterStripMinedLoopNode::fix_sunk_stores(CountedLoopEndNode* inner_cle, LoopNode* inner_cl, PhaseIterGVN* igvn, 2824 PhaseIdealLoop* iloop) { 2825 Node* cle_out = inner_cle->proj_out(false); 2826 Node* cle_tail = inner_cle->proj_out(true); 2827 if (cle_out->outcnt() > 1) { 2828 // Look for chains of stores that were sunk 2829 // out of the inner loop and are in the outer loop 2830 for (DUIterator_Fast imax, i = cle_out->fast_outs(imax); i < imax; i++) { 2831 Node* u = cle_out->fast_out(i); 2832 if (u->is_Store()) { 2833 int alias_idx = igvn->C->get_alias_index(u->adr_type()); 2834 Node* first = u; 2835 for (;;) { 2836 Node* next = first->in(MemNode::Memory); 2837 if (!next->is_Store() || next->in(0) != cle_out) { 2838 break; 2839 } 2840 assert(igvn->C->get_alias_index(next->adr_type()) == alias_idx, ""); 2841 first = next; 2842 } 2843 Node* last = u; 2844 for (;;) { 2845 Node* next = nullptr; 2846 for (DUIterator_Fast jmax, j = last->fast_outs(jmax); j < jmax; j++) { 2847 Node* uu = last->fast_out(j); 2848 if (uu->is_Store() && uu->in(0) == cle_out) { 2849 assert(next == nullptr, "only one in the outer loop"); 2850 next = uu; 2851 assert(igvn->C->get_alias_index(next->adr_type()) == alias_idx, ""); 2852 } 2853 } 2854 if (next == nullptr) { 2855 break; 2856 } 2857 last = next; 2858 } 2859 Node* phi = nullptr; 2860 for (DUIterator_Fast jmax, j = inner_cl->fast_outs(jmax); j < jmax; j++) { 2861 Node* uu = inner_cl->fast_out(j); 2862 if (uu->is_Phi()) { 2863 Node* be = uu->in(LoopNode::LoopBackControl); 2864 if (be->is_Store() && be->in(0) == inner_cl->in(LoopNode::LoopBackControl)) { 2865 assert(igvn->C->get_alias_index(uu->adr_type()) != alias_idx && igvn->C->get_alias_index(uu->adr_type()) != Compile::AliasIdxBot, "unexpected store"); 2866 } 2867 if (be == last || be == first->in(MemNode::Memory)) { 2868 assert(igvn->C->get_alias_index(uu->adr_type()) == alias_idx || igvn->C->get_alias_index(uu->adr_type()) == Compile::AliasIdxBot, "unexpected alias"); 2869 assert(phi == nullptr, "only one phi"); 2870 phi = uu; 2871 } 2872 } 2873 } 2874 #ifdef ASSERT 2875 for (DUIterator_Fast jmax, j = inner_cl->fast_outs(jmax); j < jmax; j++) { 2876 Node* uu = inner_cl->fast_out(j); 2877 if (uu->is_memory_phi()) { 2878 if (uu->adr_type() == igvn->C->get_adr_type(igvn->C->get_alias_index(u->adr_type()))) { 2879 assert(phi == uu, "what's that phi?"); 2880 } else if (uu->adr_type() == TypePtr::BOTTOM) { 2881 Node* n = uu->in(LoopNode::LoopBackControl); 2882 uint limit = igvn->C->live_nodes(); 2883 uint i = 0; 2884 while (n != uu) { 2885 i++; 2886 assert(i < limit, "infinite loop"); 2887 if (n->is_Proj()) { 2888 n = n->in(0); 2889 } else if (n->is_SafePoint() || n->is_MemBar()) { 2890 n = n->in(TypeFunc::Memory); 2891 } else if (n->is_Phi()) { 2892 n = n->in(1); 2893 } else if (n->is_MergeMem()) { 2894 n = n->as_MergeMem()->memory_at(igvn->C->get_alias_index(u->adr_type())); 2895 } else if (n->is_Store() || n->is_LoadStore() || n->is_ClearArray()) { 2896 n = n->in(MemNode::Memory); 2897 } else { 2898 n->dump(); 2899 ShouldNotReachHere(); 2900 } 2901 } 2902 } 2903 } 2904 } 2905 #endif 2906 if (phi == nullptr) { 2907 // If an entire chains was sunk, the 2908 // inner loop has no phi for that memory 2909 // slice, create one for the outer loop 2910 phi = PhiNode::make(inner_cl, first->in(MemNode::Memory), Type::MEMORY, 2911 igvn->C->get_adr_type(igvn->C->get_alias_index(u->adr_type()))); 2912 phi->set_req(LoopNode::LoopBackControl, last); 2913 phi = register_new_node(phi, inner_cl, igvn, iloop); 2914 igvn->replace_input_of(first, MemNode::Memory, phi); 2915 } else { 2916 // Or fix the outer loop fix to include 2917 // that chain of stores. 2918 Node* be = phi->in(LoopNode::LoopBackControl); 2919 assert(!(be->is_Store() && be->in(0) == inner_cl->in(LoopNode::LoopBackControl)), "store on the backedge + sunk stores: unsupported"); 2920 if (be == first->in(MemNode::Memory)) { 2921 if (be == phi->in(LoopNode::LoopBackControl)) { 2922 igvn->replace_input_of(phi, LoopNode::LoopBackControl, last); 2923 } else { 2924 igvn->replace_input_of(be, MemNode::Memory, last); 2925 } 2926 } else { 2927 #ifdef ASSERT 2928 if (be == phi->in(LoopNode::LoopBackControl)) { 2929 assert(phi->in(LoopNode::LoopBackControl) == last, ""); 2930 } else { 2931 assert(be->in(MemNode::Memory) == last, ""); 2932 } 2933 #endif 2934 } 2935 } 2936 } 2937 } 2938 } 2939 } 2940 2941 void OuterStripMinedLoopNode::adjust_strip_mined_loop(PhaseIterGVN* igvn) { 2942 // Look for the outer & inner strip mined loop, reduce number of 2943 // iterations of the inner loop, set exit condition of outer loop, 2944 // construct required phi nodes for outer loop. 2945 CountedLoopNode* inner_cl = unique_ctrl_out()->as_CountedLoop(); 2946 assert(inner_cl->is_strip_mined(), "inner loop should be strip mined"); 2947 if (LoopStripMiningIter == 0) { 2948 remove_outer_loop_and_safepoint(igvn); 2949 return; 2950 } 2951 if (LoopStripMiningIter == 1) { 2952 transform_to_counted_loop(igvn, nullptr); 2953 return; 2954 } 2955 Node* inner_iv_phi = inner_cl->phi(); 2956 if (inner_iv_phi == nullptr) { 2957 IfNode* outer_le = outer_loop_end(); 2958 Node* iff = igvn->transform(new IfNode(outer_le->in(0), outer_le->in(1), outer_le->_prob, outer_le->_fcnt)); 2959 igvn->replace_node(outer_le, iff); 2960 inner_cl->clear_strip_mined(); 2961 return; 2962 } 2963 CountedLoopEndNode* inner_cle = inner_cl->loopexit(); 2964 2965 int stride = inner_cl->stride_con(); 2966 // For a min int stride, LoopStripMiningIter * stride overflows the int range for all values of LoopStripMiningIter 2967 // except 0 or 1. Those values are handled early on in this method and causes the method to return. So for a min int 2968 // stride, the method is guaranteed to return at the next check below. 2969 jlong scaled_iters_long = ((jlong)LoopStripMiningIter) * ABS((jlong)stride); 2970 int scaled_iters = (int)scaled_iters_long; 2971 if ((jlong)scaled_iters != scaled_iters_long) { 2972 // Remove outer loop and safepoint (too few iterations) 2973 remove_outer_loop_and_safepoint(igvn); 2974 return; 2975 } 2976 jlong short_scaled_iters = LoopStripMiningIterShortLoop * ABS(stride); 2977 const TypeInt* inner_iv_t = igvn->type(inner_iv_phi)->is_int(); 2978 jlong iter_estimate = (jlong)inner_iv_t->_hi - (jlong)inner_iv_t->_lo; 2979 assert(iter_estimate > 0, "broken"); 2980 if (iter_estimate <= short_scaled_iters) { 2981 // Remove outer loop and safepoint: loop executes less than LoopStripMiningIterShortLoop 2982 remove_outer_loop_and_safepoint(igvn); 2983 return; 2984 } 2985 if (iter_estimate <= scaled_iters_long) { 2986 // We would only go through one iteration of 2987 // the outer loop: drop the outer loop but 2988 // keep the safepoint so we don't run for 2989 // too long without a safepoint 2990 IfNode* outer_le = outer_loop_end(); 2991 Node* iff = igvn->transform(new IfNode(outer_le->in(0), outer_le->in(1), outer_le->_prob, outer_le->_fcnt)); 2992 igvn->replace_node(outer_le, iff); 2993 inner_cl->clear_strip_mined(); 2994 return; 2995 } 2996 2997 Node* cle_tail = inner_cle->proj_out(true); 2998 ResourceMark rm; 2999 Node_List old_new; 3000 if (cle_tail->outcnt() > 1) { 3001 // Look for nodes on backedge of inner loop and clone them 3002 Unique_Node_List backedge_nodes; 3003 for (DUIterator_Fast imax, i = cle_tail->fast_outs(imax); i < imax; i++) { 3004 Node* u = cle_tail->fast_out(i); 3005 if (u != inner_cl) { 3006 assert(!u->is_CFG(), "control flow on the backedge?"); 3007 backedge_nodes.push(u); 3008 } 3009 } 3010 uint last = igvn->C->unique(); 3011 for (uint next = 0; next < backedge_nodes.size(); next++) { 3012 Node* n = backedge_nodes.at(next); 3013 old_new.map(n->_idx, n->clone()); 3014 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) { 3015 Node* u = n->fast_out(i); 3016 assert(!u->is_CFG(), "broken"); 3017 if (u->_idx >= last) { 3018 continue; 3019 } 3020 if (!u->is_Phi()) { 3021 backedge_nodes.push(u); 3022 } else { 3023 assert(u->in(0) == inner_cl, "strange phi on the backedge"); 3024 } 3025 } 3026 } 3027 // Put the clones on the outer loop backedge 3028 Node* le_tail = outer_loop_tail(); 3029 for (uint next = 0; next < backedge_nodes.size(); next++) { 3030 Node *n = old_new[backedge_nodes.at(next)->_idx]; 3031 for (uint i = 1; i < n->req(); i++) { 3032 if (n->in(i) != nullptr && old_new[n->in(i)->_idx] != nullptr) { 3033 n->set_req(i, old_new[n->in(i)->_idx]); 3034 } 3035 } 3036 if (n->in(0) != nullptr && n->in(0) == cle_tail) { 3037 n->set_req(0, le_tail); 3038 } 3039 igvn->register_new_node_with_optimizer(n); 3040 } 3041 } 3042 3043 Node* iv_phi = nullptr; 3044 // Make a clone of each phi in the inner loop 3045 // for the outer loop 3046 for (uint i = 0; i < inner_cl->outcnt(); i++) { 3047 Node* u = inner_cl->raw_out(i); 3048 if (u->is_Phi()) { 3049 assert(u->in(0) == inner_cl, "inconsistent"); 3050 Node* phi = u->clone(); 3051 phi->set_req(0, this); 3052 Node* be = old_new[phi->in(LoopNode::LoopBackControl)->_idx]; 3053 if (be != nullptr) { 3054 phi->set_req(LoopNode::LoopBackControl, be); 3055 } 3056 phi = igvn->transform(phi); 3057 igvn->replace_input_of(u, LoopNode::EntryControl, phi); 3058 if (u == inner_iv_phi) { 3059 iv_phi = phi; 3060 } 3061 } 3062 } 3063 3064 if (iv_phi != nullptr) { 3065 // Now adjust the inner loop's exit condition 3066 Node* limit = inner_cl->limit(); 3067 // If limit < init for stride > 0 (or limit > init for stride < 0), 3068 // the loop body is run only once. Given limit - init (init - limit resp.) 3069 // would be negative, the unsigned comparison below would cause 3070 // the loop body to be run for LoopStripMiningIter. 3071 Node* max = nullptr; 3072 if (stride > 0) { 3073 max = MaxNode::max_diff_with_zero(limit, iv_phi, TypeInt::INT, *igvn); 3074 } else { 3075 max = MaxNode::max_diff_with_zero(iv_phi, limit, TypeInt::INT, *igvn); 3076 } 3077 // sub is positive and can be larger than the max signed int 3078 // value. Use an unsigned min. 3079 Node* const_iters = igvn->intcon(scaled_iters); 3080 Node* min = MaxNode::unsigned_min(max, const_iters, TypeInt::make(0, scaled_iters, Type::WidenMin), *igvn); 3081 // min is the number of iterations for the next inner loop execution: 3082 // unsigned_min(max(limit - iv_phi, 0), scaled_iters) if stride > 0 3083 // unsigned_min(max(iv_phi - limit, 0), scaled_iters) if stride < 0 3084 3085 Node* new_limit = nullptr; 3086 if (stride > 0) { 3087 new_limit = igvn->transform(new AddINode(min, iv_phi)); 3088 } else { 3089 new_limit = igvn->transform(new SubINode(iv_phi, min)); 3090 } 3091 Node* inner_cmp = inner_cle->cmp_node(); 3092 Node* inner_bol = inner_cle->in(CountedLoopEndNode::TestValue); 3093 Node* outer_bol = inner_bol; 3094 // cmp node for inner loop may be shared 3095 inner_cmp = inner_cmp->clone(); 3096 inner_cmp->set_req(2, new_limit); 3097 inner_bol = inner_bol->clone(); 3098 inner_bol->set_req(1, igvn->transform(inner_cmp)); 3099 igvn->replace_input_of(inner_cle, CountedLoopEndNode::TestValue, igvn->transform(inner_bol)); 3100 // Set the outer loop's exit condition too 3101 igvn->replace_input_of(outer_loop_end(), 1, outer_bol); 3102 } else { 3103 assert(false, "should be able to adjust outer loop"); 3104 IfNode* outer_le = outer_loop_end(); 3105 Node* iff = igvn->transform(new IfNode(outer_le->in(0), outer_le->in(1), outer_le->_prob, outer_le->_fcnt)); 3106 igvn->replace_node(outer_le, iff); 3107 inner_cl->clear_strip_mined(); 3108 } 3109 } 3110 3111 void OuterStripMinedLoopNode::transform_to_counted_loop(PhaseIterGVN* igvn, PhaseIdealLoop* iloop) { 3112 CountedLoopNode* inner_cl = unique_ctrl_out()->as_CountedLoop(); 3113 CountedLoopEndNode* cle = inner_cl->loopexit(); 3114 Node* inner_test = cle->in(1); 3115 IfNode* outer_le = outer_loop_end(); 3116 CountedLoopEndNode* inner_cle = inner_cl->loopexit(); 3117 Node* safepoint = outer_safepoint(); 3118 3119 fix_sunk_stores(inner_cle, inner_cl, igvn, iloop); 3120 3121 // make counted loop exit test always fail 3122 ConINode* zero = igvn->intcon(0); 3123 if (iloop != nullptr) { 3124 iloop->set_ctrl(zero, igvn->C->root()); 3125 } 3126 igvn->replace_input_of(cle, 1, zero); 3127 // replace outer loop end with CountedLoopEndNode with formers' CLE's exit test 3128 Node* new_end = new CountedLoopEndNode(outer_le->in(0), inner_test, cle->_prob, cle->_fcnt); 3129 register_control(new_end, inner_cl, outer_le->in(0), igvn, iloop); 3130 if (iloop == nullptr) { 3131 igvn->replace_node(outer_le, new_end); 3132 } else { 3133 iloop->lazy_replace(outer_le, new_end); 3134 } 3135 // the backedge of the inner loop must be rewired to the new loop end 3136 Node* backedge = cle->proj_out(true); 3137 igvn->replace_input_of(backedge, 0, new_end); 3138 if (iloop != nullptr) { 3139 iloop->set_idom(backedge, new_end, iloop->dom_depth(new_end) + 1); 3140 } 3141 // make the outer loop go away 3142 igvn->replace_input_of(in(LoopBackControl), 0, igvn->C->top()); 3143 igvn->replace_input_of(this, LoopBackControl, igvn->C->top()); 3144 inner_cl->clear_strip_mined(); 3145 if (iloop != nullptr) { 3146 Unique_Node_List wq; 3147 wq.push(safepoint); 3148 3149 IdealLoopTree* outer_loop_ilt = iloop->get_loop(this); 3150 IdealLoopTree* loop = iloop->get_loop(inner_cl); 3151 3152 for (uint i = 0; i < wq.size(); i++) { 3153 Node* n = wq.at(i); 3154 for (uint j = 0; j < n->req(); ++j) { 3155 Node* in = n->in(j); 3156 if (in == nullptr || in->is_CFG()) { 3157 continue; 3158 } 3159 if (iloop->get_loop(iloop->get_ctrl(in)) != outer_loop_ilt) { 3160 continue; 3161 } 3162 assert(!loop->_body.contains(in), ""); 3163 loop->_body.push(in); 3164 wq.push(in); 3165 } 3166 } 3167 iloop->set_loop(safepoint, loop); 3168 loop->_body.push(safepoint); 3169 iloop->set_loop(safepoint->in(0), loop); 3170 loop->_body.push(safepoint->in(0)); 3171 outer_loop_ilt->_tail = igvn->C->top(); 3172 } 3173 } 3174 3175 void OuterStripMinedLoopNode::remove_outer_loop_and_safepoint(PhaseIterGVN* igvn) const { 3176 CountedLoopNode* inner_cl = unique_ctrl_out()->as_CountedLoop(); 3177 Node* outer_sfpt = outer_safepoint(); 3178 Node* outer_out = outer_loop_exit(); 3179 igvn->replace_node(outer_out, outer_sfpt->in(0)); 3180 igvn->replace_input_of(outer_sfpt, 0, igvn->C->top()); 3181 inner_cl->clear_strip_mined(); 3182 } 3183 3184 Node* OuterStripMinedLoopNode::register_new_node(Node* node, LoopNode* ctrl, PhaseIterGVN* igvn, PhaseIdealLoop* iloop) { 3185 if (iloop == nullptr) { 3186 return igvn->transform(node); 3187 } 3188 iloop->register_new_node(node, ctrl); 3189 return node; 3190 } 3191 3192 Node* OuterStripMinedLoopNode::register_control(Node* node, Node* loop, Node* idom, PhaseIterGVN* igvn, 3193 PhaseIdealLoop* iloop) { 3194 if (iloop == nullptr) { 3195 return igvn->transform(node); 3196 } 3197 iloop->register_control(node, iloop->get_loop(loop), idom); 3198 return node; 3199 } 3200 3201 const Type* OuterStripMinedLoopEndNode::Value(PhaseGVN* phase) const { 3202 if (!in(0)) return Type::TOP; 3203 if (phase->type(in(0)) == Type::TOP) 3204 return Type::TOP; 3205 3206 // Until expansion, the loop end condition is not set so this should not constant fold. 3207 if (is_expanded(phase)) { 3208 return IfNode::Value(phase); 3209 } 3210 3211 return TypeTuple::IFBOTH; 3212 } 3213 3214 bool OuterStripMinedLoopEndNode::is_expanded(PhaseGVN *phase) const { 3215 // The outer strip mined loop head only has Phi uses after expansion 3216 if (phase->is_IterGVN()) { 3217 Node* backedge = proj_out_or_null(true); 3218 if (backedge != nullptr) { 3219 Node* head = backedge->unique_ctrl_out_or_null(); 3220 if (head != nullptr && head->is_OuterStripMinedLoop()) { 3221 if (head->find_out_with(Op_Phi) != nullptr) { 3222 return true; 3223 } 3224 } 3225 } 3226 } 3227 return false; 3228 } 3229 3230 Node *OuterStripMinedLoopEndNode::Ideal(PhaseGVN *phase, bool can_reshape) { 3231 if (remove_dead_region(phase, can_reshape)) return this; 3232 3233 return nullptr; 3234 } 3235 3236 //------------------------------filtered_type-------------------------------- 3237 // Return a type based on condition control flow 3238 // A successful return will be a type that is restricted due 3239 // to a series of dominating if-tests, such as: 3240 // if (i < 10) { 3241 // if (i > 0) { 3242 // here: "i" type is [1..10) 3243 // } 3244 // } 3245 // or a control flow merge 3246 // if (i < 10) { 3247 // do { 3248 // phi( , ) -- at top of loop type is [min_int..10) 3249 // i = ? 3250 // } while ( i < 10) 3251 // 3252 const TypeInt* PhaseIdealLoop::filtered_type( Node *n, Node* n_ctrl) { 3253 assert(n && n->bottom_type()->is_int(), "must be int"); 3254 const TypeInt* filtered_t = nullptr; 3255 if (!n->is_Phi()) { 3256 assert(n_ctrl != nullptr || n_ctrl == C->top(), "valid control"); 3257 filtered_t = filtered_type_from_dominators(n, n_ctrl); 3258 3259 } else { 3260 Node* phi = n->as_Phi(); 3261 Node* region = phi->in(0); 3262 assert(n_ctrl == nullptr || n_ctrl == region, "ctrl parameter must be region"); 3263 if (region && region != C->top()) { 3264 for (uint i = 1; i < phi->req(); i++) { 3265 Node* val = phi->in(i); 3266 Node* use_c = region->in(i); 3267 const TypeInt* val_t = filtered_type_from_dominators(val, use_c); 3268 if (val_t != nullptr) { 3269 if (filtered_t == nullptr) { 3270 filtered_t = val_t; 3271 } else { 3272 filtered_t = filtered_t->meet(val_t)->is_int(); 3273 } 3274 } 3275 } 3276 } 3277 } 3278 const TypeInt* n_t = _igvn.type(n)->is_int(); 3279 if (filtered_t != nullptr) { 3280 n_t = n_t->join(filtered_t)->is_int(); 3281 } 3282 return n_t; 3283 } 3284 3285 3286 //------------------------------filtered_type_from_dominators-------------------------------- 3287 // Return a possibly more restrictive type for val based on condition control flow of dominators 3288 const TypeInt* PhaseIdealLoop::filtered_type_from_dominators( Node* val, Node *use_ctrl) { 3289 if (val->is_Con()) { 3290 return val->bottom_type()->is_int(); 3291 } 3292 uint if_limit = 10; // Max number of dominating if's visited 3293 const TypeInt* rtn_t = nullptr; 3294 3295 if (use_ctrl && use_ctrl != C->top()) { 3296 Node* val_ctrl = get_ctrl(val); 3297 uint val_dom_depth = dom_depth(val_ctrl); 3298 Node* pred = use_ctrl; 3299 uint if_cnt = 0; 3300 while (if_cnt < if_limit) { 3301 if ((pred->Opcode() == Op_IfTrue || pred->Opcode() == Op_IfFalse)) { 3302 if_cnt++; 3303 const TypeInt* if_t = IfNode::filtered_int_type(&_igvn, val, pred); 3304 if (if_t != nullptr) { 3305 if (rtn_t == nullptr) { 3306 rtn_t = if_t; 3307 } else { 3308 rtn_t = rtn_t->join(if_t)->is_int(); 3309 } 3310 } 3311 } 3312 pred = idom(pred); 3313 if (pred == nullptr || pred == C->top()) { 3314 break; 3315 } 3316 // Stop if going beyond definition block of val 3317 if (dom_depth(pred) < val_dom_depth) { 3318 break; 3319 } 3320 } 3321 } 3322 return rtn_t; 3323 } 3324 3325 3326 //------------------------------dump_spec-------------------------------------- 3327 // Dump special per-node info 3328 #ifndef PRODUCT 3329 void CountedLoopEndNode::dump_spec(outputStream *st) const { 3330 if( in(TestValue) != nullptr && in(TestValue)->is_Bool() ) { 3331 BoolTest bt( test_trip()); // Added this for g++. 3332 3333 st->print("["); 3334 bt.dump_on(st); 3335 st->print("]"); 3336 } 3337 st->print(" "); 3338 IfNode::dump_spec(st); 3339 } 3340 #endif 3341 3342 //============================================================================= 3343 //------------------------------is_member-------------------------------------- 3344 // Is 'l' a member of 'this'? 3345 bool IdealLoopTree::is_member(const IdealLoopTree *l) const { 3346 while( l->_nest > _nest ) l = l->_parent; 3347 return l == this; 3348 } 3349 3350 //------------------------------set_nest--------------------------------------- 3351 // Set loop tree nesting depth. Accumulate _has_call bits. 3352 int IdealLoopTree::set_nest( uint depth ) { 3353 assert(depth <= SHRT_MAX, "sanity"); 3354 _nest = depth; 3355 int bits = _has_call; 3356 if( _child ) bits |= _child->set_nest(depth+1); 3357 if( bits ) _has_call = 1; 3358 if( _next ) bits |= _next ->set_nest(depth ); 3359 return bits; 3360 } 3361 3362 //------------------------------split_fall_in---------------------------------- 3363 // Split out multiple fall-in edges from the loop header. Move them to a 3364 // private RegionNode before the loop. This becomes the loop landing pad. 3365 void IdealLoopTree::split_fall_in( PhaseIdealLoop *phase, int fall_in_cnt ) { 3366 PhaseIterGVN &igvn = phase->_igvn; 3367 uint i; 3368 3369 // Make a new RegionNode to be the landing pad. 3370 RegionNode* landing_pad = new RegionNode(fall_in_cnt + 1); 3371 phase->set_loop(landing_pad,_parent); 3372 // If _head was irreducible loop entry, landing_pad may now be too 3373 landing_pad->set_loop_status(_head->as_Region()->loop_status()); 3374 // Gather all the fall-in control paths into the landing pad 3375 uint icnt = fall_in_cnt; 3376 uint oreq = _head->req(); 3377 for( i = oreq-1; i>0; i-- ) 3378 if( !phase->is_member( this, _head->in(i) ) ) 3379 landing_pad->set_req(icnt--,_head->in(i)); 3380 3381 // Peel off PhiNode edges as well 3382 for (DUIterator_Fast jmax, j = _head->fast_outs(jmax); j < jmax; j++) { 3383 Node *oj = _head->fast_out(j); 3384 if( oj->is_Phi() ) { 3385 PhiNode* old_phi = oj->as_Phi(); 3386 assert( old_phi->region() == _head, "" ); 3387 igvn.hash_delete(old_phi); // Yank from hash before hacking edges 3388 Node *p = PhiNode::make_blank(landing_pad, old_phi); 3389 uint icnt = fall_in_cnt; 3390 for( i = oreq-1; i>0; i-- ) { 3391 if( !phase->is_member( this, _head->in(i) ) ) { 3392 p->init_req(icnt--, old_phi->in(i)); 3393 // Go ahead and clean out old edges from old phi 3394 old_phi->del_req(i); 3395 } 3396 } 3397 // Search for CSE's here, because ZKM.jar does a lot of 3398 // loop hackery and we need to be a little incremental 3399 // with the CSE to avoid O(N^2) node blow-up. 3400 Node *p2 = igvn.hash_find_insert(p); // Look for a CSE 3401 if( p2 ) { // Found CSE 3402 p->destruct(&igvn); // Recover useless new node 3403 p = p2; // Use old node 3404 } else { 3405 igvn.register_new_node_with_optimizer(p, old_phi); 3406 } 3407 // Make old Phi refer to new Phi. 3408 old_phi->add_req(p); 3409 // Check for the special case of making the old phi useless and 3410 // disappear it. In JavaGrande I have a case where this useless 3411 // Phi is the loop limit and prevents recognizing a CountedLoop 3412 // which in turn prevents removing an empty loop. 3413 Node *id_old_phi = old_phi->Identity(&igvn); 3414 if( id_old_phi != old_phi ) { // Found a simple identity? 3415 // Note that I cannot call 'replace_node' here, because 3416 // that will yank the edge from old_phi to the Region and 3417 // I'm mid-iteration over the Region's uses. 3418 for (DUIterator_Last imin, i = old_phi->last_outs(imin); i >= imin; ) { 3419 Node* use = old_phi->last_out(i); 3420 igvn.rehash_node_delayed(use); 3421 uint uses_found = 0; 3422 for (uint j = 0; j < use->len(); j++) { 3423 if (use->in(j) == old_phi) { 3424 if (j < use->req()) use->set_req (j, id_old_phi); 3425 else use->set_prec(j, id_old_phi); 3426 uses_found++; 3427 } 3428 } 3429 i -= uses_found; // we deleted 1 or more copies of this edge 3430 } 3431 } 3432 igvn._worklist.push(old_phi); 3433 } 3434 } 3435 // Finally clean out the fall-in edges from the RegionNode 3436 for( i = oreq-1; i>0; i-- ) { 3437 if( !phase->is_member( this, _head->in(i) ) ) { 3438 _head->del_req(i); 3439 } 3440 } 3441 igvn.rehash_node_delayed(_head); 3442 // Transform landing pad 3443 igvn.register_new_node_with_optimizer(landing_pad, _head); 3444 // Insert landing pad into the header 3445 _head->add_req(landing_pad); 3446 } 3447 3448 //------------------------------split_outer_loop------------------------------- 3449 // Split out the outermost loop from this shared header. 3450 void IdealLoopTree::split_outer_loop( PhaseIdealLoop *phase ) { 3451 PhaseIterGVN &igvn = phase->_igvn; 3452 3453 // Find index of outermost loop; it should also be my tail. 3454 uint outer_idx = 1; 3455 while( _head->in(outer_idx) != _tail ) outer_idx++; 3456 3457 // Make a LoopNode for the outermost loop. 3458 Node *ctl = _head->in(LoopNode::EntryControl); 3459 Node *outer = new LoopNode( ctl, _head->in(outer_idx) ); 3460 outer = igvn.register_new_node_with_optimizer(outer, _head); 3461 phase->set_created_loop_node(); 3462 3463 // Outermost loop falls into '_head' loop 3464 _head->set_req(LoopNode::EntryControl, outer); 3465 _head->del_req(outer_idx); 3466 // Split all the Phis up between '_head' loop and 'outer' loop. 3467 for (DUIterator_Fast jmax, j = _head->fast_outs(jmax); j < jmax; j++) { 3468 Node *out = _head->fast_out(j); 3469 if( out->is_Phi() ) { 3470 PhiNode *old_phi = out->as_Phi(); 3471 assert( old_phi->region() == _head, "" ); 3472 Node *phi = PhiNode::make_blank(outer, old_phi); 3473 phi->init_req(LoopNode::EntryControl, old_phi->in(LoopNode::EntryControl)); 3474 phi->init_req(LoopNode::LoopBackControl, old_phi->in(outer_idx)); 3475 phi = igvn.register_new_node_with_optimizer(phi, old_phi); 3476 // Make old Phi point to new Phi on the fall-in path 3477 igvn.replace_input_of(old_phi, LoopNode::EntryControl, phi); 3478 old_phi->del_req(outer_idx); 3479 } 3480 } 3481 3482 // Use the new loop head instead of the old shared one 3483 _head = outer; 3484 phase->set_loop(_head, this); 3485 } 3486 3487 //------------------------------fix_parent------------------------------------- 3488 static void fix_parent( IdealLoopTree *loop, IdealLoopTree *parent ) { 3489 loop->_parent = parent; 3490 if( loop->_child ) fix_parent( loop->_child, loop ); 3491 if( loop->_next ) fix_parent( loop->_next , parent ); 3492 } 3493 3494 //------------------------------estimate_path_freq----------------------------- 3495 static float estimate_path_freq( Node *n ) { 3496 // Try to extract some path frequency info 3497 IfNode *iff; 3498 for( int i = 0; i < 50; i++ ) { // Skip through a bunch of uncommon tests 3499 uint nop = n->Opcode(); 3500 if( nop == Op_SafePoint ) { // Skip any safepoint 3501 n = n->in(0); 3502 continue; 3503 } 3504 if( nop == Op_CatchProj ) { // Get count from a prior call 3505 // Assume call does not always throw exceptions: means the call-site 3506 // count is also the frequency of the fall-through path. 3507 assert( n->is_CatchProj(), "" ); 3508 if( ((CatchProjNode*)n)->_con != CatchProjNode::fall_through_index ) 3509 return 0.0f; // Assume call exception path is rare 3510 Node *call = n->in(0)->in(0)->in(0); 3511 assert( call->is_Call(), "expect a call here" ); 3512 const JVMState *jvms = ((CallNode*)call)->jvms(); 3513 ciMethodData* methodData = jvms->method()->method_data(); 3514 if (!methodData->is_mature()) return 0.0f; // No call-site data 3515 ciProfileData* data = methodData->bci_to_data(jvms->bci()); 3516 if ((data == nullptr) || !data->is_CounterData()) { 3517 // no call profile available, try call's control input 3518 n = n->in(0); 3519 continue; 3520 } 3521 return data->as_CounterData()->count()/FreqCountInvocations; 3522 } 3523 // See if there's a gating IF test 3524 Node *n_c = n->in(0); 3525 if( !n_c->is_If() ) break; // No estimate available 3526 iff = n_c->as_If(); 3527 if( iff->_fcnt != COUNT_UNKNOWN ) // Have a valid count? 3528 // Compute how much count comes on this path 3529 return ((nop == Op_IfTrue) ? iff->_prob : 1.0f - iff->_prob) * iff->_fcnt; 3530 // Have no count info. Skip dull uncommon-trap like branches. 3531 if( (nop == Op_IfTrue && iff->_prob < PROB_LIKELY_MAG(5)) || 3532 (nop == Op_IfFalse && iff->_prob > PROB_UNLIKELY_MAG(5)) ) 3533 break; 3534 // Skip through never-taken branch; look for a real loop exit. 3535 n = iff->in(0); 3536 } 3537 return 0.0f; // No estimate available 3538 } 3539 3540 //------------------------------merge_many_backedges--------------------------- 3541 // Merge all the backedges from the shared header into a private Region. 3542 // Feed that region as the one backedge to this loop. 3543 void IdealLoopTree::merge_many_backedges( PhaseIdealLoop *phase ) { 3544 uint i; 3545 3546 // Scan for the top 2 hottest backedges 3547 float hotcnt = 0.0f; 3548 float warmcnt = 0.0f; 3549 uint hot_idx = 0; 3550 // Loop starts at 2 because slot 1 is the fall-in path 3551 for( i = 2; i < _head->req(); i++ ) { 3552 float cnt = estimate_path_freq(_head->in(i)); 3553 if( cnt > hotcnt ) { // Grab hottest path 3554 warmcnt = hotcnt; 3555 hotcnt = cnt; 3556 hot_idx = i; 3557 } else if( cnt > warmcnt ) { // And 2nd hottest path 3558 warmcnt = cnt; 3559 } 3560 } 3561 3562 // See if the hottest backedge is worthy of being an inner loop 3563 // by being much hotter than the next hottest backedge. 3564 if( hotcnt <= 0.0001 || 3565 hotcnt < 2.0*warmcnt ) hot_idx = 0;// No hot backedge 3566 3567 // Peel out the backedges into a private merge point; peel 3568 // them all except optionally hot_idx. 3569 PhaseIterGVN &igvn = phase->_igvn; 3570 3571 Node *hot_tail = nullptr; 3572 // Make a Region for the merge point 3573 Node *r = new RegionNode(1); 3574 for( i = 2; i < _head->req(); i++ ) { 3575 if( i != hot_idx ) 3576 r->add_req( _head->in(i) ); 3577 else hot_tail = _head->in(i); 3578 } 3579 igvn.register_new_node_with_optimizer(r, _head); 3580 // Plug region into end of loop _head, followed by hot_tail 3581 while( _head->req() > 3 ) _head->del_req( _head->req()-1 ); 3582 igvn.replace_input_of(_head, 2, r); 3583 if( hot_idx ) _head->add_req(hot_tail); 3584 3585 // Split all the Phis up between '_head' loop and the Region 'r' 3586 for (DUIterator_Fast jmax, j = _head->fast_outs(jmax); j < jmax; j++) { 3587 Node *out = _head->fast_out(j); 3588 if( out->is_Phi() ) { 3589 PhiNode* n = out->as_Phi(); 3590 igvn.hash_delete(n); // Delete from hash before hacking edges 3591 Node *hot_phi = nullptr; 3592 Node *phi = new PhiNode(r, n->type(), n->adr_type()); 3593 // Check all inputs for the ones to peel out 3594 uint j = 1; 3595 for( uint i = 2; i < n->req(); i++ ) { 3596 if( i != hot_idx ) 3597 phi->set_req( j++, n->in(i) ); 3598 else hot_phi = n->in(i); 3599 } 3600 // Register the phi but do not transform until whole place transforms 3601 igvn.register_new_node_with_optimizer(phi, n); 3602 // Add the merge phi to the old Phi 3603 while( n->req() > 3 ) n->del_req( n->req()-1 ); 3604 igvn.replace_input_of(n, 2, phi); 3605 if( hot_idx ) n->add_req(hot_phi); 3606 } 3607 } 3608 3609 3610 // Insert a new IdealLoopTree inserted below me. Turn it into a clone 3611 // of self loop tree. Turn self into a loop headed by _head and with 3612 // tail being the new merge point. 3613 IdealLoopTree *ilt = new IdealLoopTree( phase, _head, _tail ); 3614 phase->set_loop(_tail,ilt); // Adjust tail 3615 _tail = r; // Self's tail is new merge point 3616 phase->set_loop(r,this); 3617 ilt->_child = _child; // New guy has my children 3618 _child = ilt; // Self has new guy as only child 3619 ilt->_parent = this; // new guy has self for parent 3620 ilt->_nest = _nest; // Same nesting depth (for now) 3621 3622 // Starting with 'ilt', look for child loop trees using the same shared 3623 // header. Flatten these out; they will no longer be loops in the end. 3624 IdealLoopTree **pilt = &_child; 3625 while( ilt ) { 3626 if( ilt->_head == _head ) { 3627 uint i; 3628 for( i = 2; i < _head->req(); i++ ) 3629 if( _head->in(i) == ilt->_tail ) 3630 break; // Still a loop 3631 if( i == _head->req() ) { // No longer a loop 3632 // Flatten ilt. Hang ilt's "_next" list from the end of 3633 // ilt's '_child' list. Move the ilt's _child up to replace ilt. 3634 IdealLoopTree **cp = &ilt->_child; 3635 while( *cp ) cp = &(*cp)->_next; // Find end of child list 3636 *cp = ilt->_next; // Hang next list at end of child list 3637 *pilt = ilt->_child; // Move child up to replace ilt 3638 ilt->_head = nullptr; // Flag as a loop UNIONED into parent 3639 ilt = ilt->_child; // Repeat using new ilt 3640 continue; // do not advance over ilt->_child 3641 } 3642 assert( ilt->_tail == hot_tail, "expected to only find the hot inner loop here" ); 3643 phase->set_loop(_head,ilt); 3644 } 3645 pilt = &ilt->_child; // Advance to next 3646 ilt = *pilt; 3647 } 3648 3649 if( _child ) fix_parent( _child, this ); 3650 } 3651 3652 //------------------------------beautify_loops--------------------------------- 3653 // Split shared headers and insert loop landing pads. 3654 // Insert a LoopNode to replace the RegionNode. 3655 // Return TRUE if loop tree is structurally changed. 3656 bool IdealLoopTree::beautify_loops( PhaseIdealLoop *phase ) { 3657 bool result = false; 3658 // Cache parts in locals for easy 3659 PhaseIterGVN &igvn = phase->_igvn; 3660 3661 igvn.hash_delete(_head); // Yank from hash before hacking edges 3662 3663 // Check for multiple fall-in paths. Peel off a landing pad if need be. 3664 int fall_in_cnt = 0; 3665 for( uint i = 1; i < _head->req(); i++ ) 3666 if( !phase->is_member( this, _head->in(i) ) ) 3667 fall_in_cnt++; 3668 assert( fall_in_cnt, "at least 1 fall-in path" ); 3669 if( fall_in_cnt > 1 ) // Need a loop landing pad to merge fall-ins 3670 split_fall_in( phase, fall_in_cnt ); 3671 3672 // Swap inputs to the _head and all Phis to move the fall-in edge to 3673 // the left. 3674 fall_in_cnt = 1; 3675 while( phase->is_member( this, _head->in(fall_in_cnt) ) ) 3676 fall_in_cnt++; 3677 if( fall_in_cnt > 1 ) { 3678 // Since I am just swapping inputs I do not need to update def-use info 3679 Node *tmp = _head->in(1); 3680 igvn.rehash_node_delayed(_head); 3681 _head->set_req( 1, _head->in(fall_in_cnt) ); 3682 _head->set_req( fall_in_cnt, tmp ); 3683 // Swap also all Phis 3684 for (DUIterator_Fast imax, i = _head->fast_outs(imax); i < imax; i++) { 3685 Node* phi = _head->fast_out(i); 3686 if( phi->is_Phi() ) { 3687 igvn.rehash_node_delayed(phi); // Yank from hash before hacking edges 3688 tmp = phi->in(1); 3689 phi->set_req( 1, phi->in(fall_in_cnt) ); 3690 phi->set_req( fall_in_cnt, tmp ); 3691 } 3692 } 3693 } 3694 assert( !phase->is_member( this, _head->in(1) ), "left edge is fall-in" ); 3695 assert( phase->is_member( this, _head->in(2) ), "right edge is loop" ); 3696 3697 // If I am a shared header (multiple backedges), peel off the many 3698 // backedges into a private merge point and use the merge point as 3699 // the one true backedge. 3700 if (_head->req() > 3) { 3701 // Merge the many backedges into a single backedge but leave 3702 // the hottest backedge as separate edge for the following peel. 3703 if (!_irreducible) { 3704 merge_many_backedges( phase ); 3705 } 3706 3707 // When recursively beautify my children, split_fall_in can change 3708 // loop tree structure when I am an irreducible loop. Then the head 3709 // of my children has a req() not bigger than 3. Here we need to set 3710 // result to true to catch that case in order to tell the caller to 3711 // rebuild loop tree. See issue JDK-8244407 for details. 3712 result = true; 3713 } 3714 3715 // If I have one hot backedge, peel off myself loop. 3716 // I better be the outermost loop. 3717 if (_head->req() > 3 && !_irreducible) { 3718 split_outer_loop( phase ); 3719 result = true; 3720 3721 } else if (!_head->is_Loop() && !_irreducible) { 3722 // Make a new LoopNode to replace the old loop head 3723 Node *l = new LoopNode( _head->in(1), _head->in(2) ); 3724 l = igvn.register_new_node_with_optimizer(l, _head); 3725 phase->set_created_loop_node(); 3726 // Go ahead and replace _head 3727 phase->_igvn.replace_node( _head, l ); 3728 _head = l; 3729 phase->set_loop(_head, this); 3730 } 3731 3732 // Now recursively beautify nested loops 3733 if( _child ) result |= _child->beautify_loops( phase ); 3734 if( _next ) result |= _next ->beautify_loops( phase ); 3735 return result; 3736 } 3737 3738 //------------------------------allpaths_check_safepts---------------------------- 3739 // Allpaths backwards scan. Starting at the head, traversing all backedges, and the body. Terminating each path at first 3740 // safepoint encountered. Helper for check_safepts. 3741 void IdealLoopTree::allpaths_check_safepts(VectorSet &visited, Node_List &stack) { 3742 assert(stack.size() == 0, "empty stack"); 3743 stack.push(_head); 3744 visited.clear(); 3745 visited.set(_head->_idx); 3746 while (stack.size() > 0) { 3747 Node* n = stack.pop(); 3748 if (n->is_Call() && n->as_Call()->guaranteed_safepoint()) { 3749 // Terminate this path 3750 } else if (n->Opcode() == Op_SafePoint) { 3751 if (_phase->get_loop(n) != this) { 3752 if (_required_safept == nullptr) _required_safept = new Node_List(); 3753 // save the first we run into on that path: closest to the tail if the head has a single backedge 3754 _required_safept->push(n); 3755 } 3756 // Terminate this path 3757 } else { 3758 uint start = n->is_Region() ? 1 : 0; 3759 uint end = n->is_Region() && (!n->is_Loop() || n == _head) ? n->req() : start + 1; 3760 for (uint i = start; i < end; i++) { 3761 Node* in = n->in(i); 3762 assert(in->is_CFG(), "must be"); 3763 if (!visited.test_set(in->_idx) && is_member(_phase->get_loop(in))) { 3764 stack.push(in); 3765 } 3766 } 3767 } 3768 } 3769 } 3770 3771 //------------------------------check_safepts---------------------------- 3772 // Given dominators, try to find loops with calls that must always be 3773 // executed (call dominates loop tail). These loops do not need non-call 3774 // safepoints (ncsfpt). 3775 // 3776 // A complication is that a safepoint in a inner loop may be needed 3777 // by an outer loop. In the following, the inner loop sees it has a 3778 // call (block 3) on every path from the head (block 2) to the 3779 // backedge (arc 3->2). So it deletes the ncsfpt (non-call safepoint) 3780 // in block 2, _but_ this leaves the outer loop without a safepoint. 3781 // 3782 // entry 0 3783 // | 3784 // v 3785 // outer 1,2 +->1 3786 // | | 3787 // | v 3788 // | 2<---+ ncsfpt in 2 3789 // |_/|\ | 3790 // | v | 3791 // inner 2,3 / 3 | call in 3 3792 // / | | 3793 // v +--+ 3794 // exit 4 3795 // 3796 // 3797 // This method creates a list (_required_safept) of ncsfpt nodes that must 3798 // be protected is created for each loop. When a ncsfpt maybe deleted, it 3799 // is first looked for in the lists for the outer loops of the current loop. 3800 // 3801 // The insights into the problem: 3802 // A) counted loops are okay 3803 // B) innermost loops are okay (only an inner loop can delete 3804 // a ncsfpt needed by an outer loop) 3805 // C) a loop is immune from an inner loop deleting a safepoint 3806 // if the loop has a call on the idom-path 3807 // D) a loop is also immune if it has a ncsfpt (non-call safepoint) on the 3808 // idom-path that is not in a nested loop 3809 // E) otherwise, an ncsfpt on the idom-path that is nested in an inner 3810 // loop needs to be prevented from deletion by an inner loop 3811 // 3812 // There are two analyses: 3813 // 1) The first, and cheaper one, scans the loop body from 3814 // tail to head following the idom (immediate dominator) 3815 // chain, looking for the cases (C,D,E) above. 3816 // Since inner loops are scanned before outer loops, there is summary 3817 // information about inner loops. Inner loops can be skipped over 3818 // when the tail of an inner loop is encountered. 3819 // 3820 // 2) The second, invoked if the first fails to find a call or ncsfpt on 3821 // the idom path (which is rare), scans all predecessor control paths 3822 // from the tail to the head, terminating a path when a call or sfpt 3823 // is encountered, to find the ncsfpt's that are closest to the tail. 3824 // 3825 void IdealLoopTree::check_safepts(VectorSet &visited, Node_List &stack) { 3826 // Bottom up traversal 3827 IdealLoopTree* ch = _child; 3828 if (_child) _child->check_safepts(visited, stack); 3829 if (_next) _next ->check_safepts(visited, stack); 3830 3831 if (!_head->is_CountedLoop() && !_has_sfpt && _parent != nullptr) { 3832 bool has_call = false; // call on dom-path 3833 bool has_local_ncsfpt = false; // ncsfpt on dom-path at this loop depth 3834 Node* nonlocal_ncsfpt = nullptr; // ncsfpt on dom-path at a deeper depth 3835 if (!_irreducible) { 3836 // Scan the dom-path nodes from tail to head 3837 for (Node* n = tail(); n != _head; n = _phase->idom(n)) { 3838 if (n->is_Call() && n->as_Call()->guaranteed_safepoint()) { 3839 has_call = true; 3840 _has_sfpt = 1; // Then no need for a safept! 3841 break; 3842 } else if (n->Opcode() == Op_SafePoint) { 3843 if (_phase->get_loop(n) == this) { 3844 has_local_ncsfpt = true; 3845 break; 3846 } 3847 if (nonlocal_ncsfpt == nullptr) { 3848 nonlocal_ncsfpt = n; // save the one closest to the tail 3849 } 3850 } else { 3851 IdealLoopTree* nlpt = _phase->get_loop(n); 3852 if (this != nlpt) { 3853 // If at an inner loop tail, see if the inner loop has already 3854 // recorded seeing a call on the dom-path (and stop.) If not, 3855 // jump to the head of the inner loop. 3856 assert(is_member(nlpt), "nested loop"); 3857 Node* tail = nlpt->_tail; 3858 if (tail->in(0)->is_If()) tail = tail->in(0); 3859 if (n == tail) { 3860 // If inner loop has call on dom-path, so does outer loop 3861 if (nlpt->_has_sfpt) { 3862 has_call = true; 3863 _has_sfpt = 1; 3864 break; 3865 } 3866 // Skip to head of inner loop 3867 assert(_phase->is_dominator(_head, nlpt->_head), "inner head dominated by outer head"); 3868 n = nlpt->_head; 3869 if (_head == n) { 3870 // this and nlpt (inner loop) have the same loop head. This should not happen because 3871 // during beautify_loops we call merge_many_backedges. However, infinite loops may not 3872 // have been attached to the loop-tree during build_loop_tree before beautify_loops, 3873 // but then attached in the build_loop_tree afterwards, and so still have unmerged 3874 // backedges. Check if we are indeed in an infinite subgraph, and terminate the scan, 3875 // since we have reached the loop head of this. 3876 assert(_head->as_Region()->is_in_infinite_subgraph(), 3877 "only expect unmerged backedges in infinite loops"); 3878 break; 3879 } 3880 } 3881 } 3882 } 3883 } 3884 } 3885 // Record safept's that this loop needs preserved when an 3886 // inner loop attempts to delete it's safepoints. 3887 if (_child != nullptr && !has_call && !has_local_ncsfpt) { 3888 if (nonlocal_ncsfpt != nullptr) { 3889 if (_required_safept == nullptr) _required_safept = new Node_List(); 3890 _required_safept->push(nonlocal_ncsfpt); 3891 } else { 3892 // Failed to find a suitable safept on the dom-path. Now use 3893 // an all paths walk from tail to head, looking for safepoints to preserve. 3894 allpaths_check_safepts(visited, stack); 3895 } 3896 } 3897 } 3898 } 3899 3900 //---------------------------is_deleteable_safept---------------------------- 3901 // Is safept not required by an outer loop? 3902 bool PhaseIdealLoop::is_deleteable_safept(Node* sfpt) { 3903 assert(sfpt->Opcode() == Op_SafePoint, ""); 3904 IdealLoopTree* lp = get_loop(sfpt)->_parent; 3905 while (lp != nullptr) { 3906 Node_List* sfpts = lp->_required_safept; 3907 if (sfpts != nullptr) { 3908 for (uint i = 0; i < sfpts->size(); i++) { 3909 if (sfpt == sfpts->at(i)) 3910 return false; 3911 } 3912 } 3913 lp = lp->_parent; 3914 } 3915 return true; 3916 } 3917 3918 //---------------------------replace_parallel_iv------------------------------- 3919 // Replace parallel induction variable (parallel to trip counter) 3920 void PhaseIdealLoop::replace_parallel_iv(IdealLoopTree *loop) { 3921 assert(loop->_head->is_CountedLoop(), ""); 3922 CountedLoopNode *cl = loop->_head->as_CountedLoop(); 3923 if (!cl->is_valid_counted_loop(T_INT)) { 3924 return; // skip malformed counted loop 3925 } 3926 Node *incr = cl->incr(); 3927 if (incr == nullptr) { 3928 return; // Dead loop? 3929 } 3930 Node *init = cl->init_trip(); 3931 Node *phi = cl->phi(); 3932 int stride_con = cl->stride_con(); 3933 3934 // Visit all children, looking for Phis 3935 for (DUIterator i = cl->outs(); cl->has_out(i); i++) { 3936 Node *out = cl->out(i); 3937 // Look for other phis (secondary IVs). Skip dead ones 3938 if (!out->is_Phi() || out == phi || !has_node(out)) { 3939 continue; 3940 } 3941 3942 PhiNode* phi2 = out->as_Phi(); 3943 Node* incr2 = phi2->in(LoopNode::LoopBackControl); 3944 // Look for induction variables of the form: X += constant 3945 if (phi2->region() != loop->_head || 3946 incr2->req() != 3 || 3947 incr2->in(1)->uncast() != phi2 || 3948 incr2 == incr || 3949 incr2->Opcode() != Op_AddI || 3950 !incr2->in(2)->is_Con()) { 3951 continue; 3952 } 3953 3954 if (incr2->in(1)->is_ConstraintCast() && 3955 !(incr2->in(1)->in(0)->is_IfProj() && incr2->in(1)->in(0)->in(0)->is_RangeCheck())) { 3956 // Skip AddI->CastII->Phi case if CastII is not controlled by local RangeCheck 3957 continue; 3958 } 3959 // Check for parallel induction variable (parallel to trip counter) 3960 // via an affine function. In particular, count-down loops with 3961 // count-up array indices are common. We only RCE references off 3962 // the trip-counter, so we need to convert all these to trip-counter 3963 // expressions. 3964 Node* init2 = phi2->in(LoopNode::EntryControl); 3965 int stride_con2 = incr2->in(2)->get_int(); 3966 3967 // The ratio of the two strides cannot be represented as an int 3968 // if stride_con2 is min_int and stride_con is -1. 3969 if (stride_con2 == min_jint && stride_con == -1) { 3970 continue; 3971 } 3972 3973 // The general case here gets a little tricky. We want to find the 3974 // GCD of all possible parallel IV's and make a new IV using this 3975 // GCD for the loop. Then all possible IVs are simple multiples of 3976 // the GCD. In practice, this will cover very few extra loops. 3977 // Instead we require 'stride_con2' to be a multiple of 'stride_con', 3978 // where +/-1 is the common case, but other integer multiples are 3979 // also easy to handle. 3980 int ratio_con = stride_con2/stride_con; 3981 3982 if ((ratio_con * stride_con) == stride_con2) { // Check for exact 3983 #ifndef PRODUCT 3984 if (TraceLoopOpts) { 3985 tty->print("Parallel IV: %d ", phi2->_idx); 3986 loop->dump_head(); 3987 } 3988 #endif 3989 // Convert to using the trip counter. The parallel induction 3990 // variable differs from the trip counter by a loop-invariant 3991 // amount, the difference between their respective initial values. 3992 // It is scaled by the 'ratio_con'. 3993 Node* ratio = _igvn.intcon(ratio_con); 3994 set_ctrl(ratio, C->root()); 3995 Node* ratio_init = new MulINode(init, ratio); 3996 _igvn.register_new_node_with_optimizer(ratio_init, init); 3997 set_early_ctrl(ratio_init, false); 3998 Node* diff = new SubINode(init2, ratio_init); 3999 _igvn.register_new_node_with_optimizer(diff, init2); 4000 set_early_ctrl(diff, false); 4001 Node* ratio_idx = new MulINode(phi, ratio); 4002 _igvn.register_new_node_with_optimizer(ratio_idx, phi); 4003 set_ctrl(ratio_idx, cl); 4004 Node* add = new AddINode(ratio_idx, diff); 4005 _igvn.register_new_node_with_optimizer(add); 4006 set_ctrl(add, cl); 4007 _igvn.replace_node( phi2, add ); 4008 // Sometimes an induction variable is unused 4009 if (add->outcnt() == 0) { 4010 _igvn.remove_dead_node(add); 4011 } 4012 --i; // deleted this phi; rescan starting with next position 4013 continue; 4014 } 4015 } 4016 } 4017 4018 void IdealLoopTree::remove_safepoints(PhaseIdealLoop* phase, bool keep_one) { 4019 Node* keep = nullptr; 4020 if (keep_one) { 4021 // Look for a safepoint on the idom-path. 4022 for (Node* i = tail(); i != _head; i = phase->idom(i)) { 4023 if (i->Opcode() == Op_SafePoint && phase->get_loop(i) == this) { 4024 keep = i; 4025 break; // Found one 4026 } 4027 } 4028 } 4029 4030 // Don't remove any safepoints if it is requested to keep a single safepoint and 4031 // no safepoint was found on idom-path. It is not safe to remove any safepoint 4032 // in this case since there's no safepoint dominating all paths in the loop body. 4033 bool prune = !keep_one || keep != nullptr; 4034 4035 // Delete other safepoints in this loop. 4036 Node_List* sfpts = _safepts; 4037 if (prune && sfpts != nullptr) { 4038 assert(keep == nullptr || keep->Opcode() == Op_SafePoint, "not safepoint"); 4039 for (uint i = 0; i < sfpts->size(); i++) { 4040 Node* n = sfpts->at(i); 4041 assert(phase->get_loop(n) == this, ""); 4042 if (n != keep && phase->is_deleteable_safept(n)) { 4043 phase->lazy_replace(n, n->in(TypeFunc::Control)); 4044 } 4045 } 4046 } 4047 } 4048 4049 //------------------------------counted_loop----------------------------------- 4050 // Convert to counted loops where possible 4051 void IdealLoopTree::counted_loop( PhaseIdealLoop *phase ) { 4052 4053 // For grins, set the inner-loop flag here 4054 if (!_child) { 4055 if (_head->is_Loop()) _head->as_Loop()->set_inner_loop(); 4056 } 4057 4058 IdealLoopTree* loop = this; 4059 if (_head->is_CountedLoop() || 4060 phase->is_counted_loop(_head, loop, T_INT)) { 4061 4062 if (LoopStripMiningIter == 0 || _head->as_CountedLoop()->is_strip_mined()) { 4063 // Indicate we do not need a safepoint here 4064 _has_sfpt = 1; 4065 } 4066 4067 // Remove safepoints 4068 bool keep_one_sfpt = !(_has_call || _has_sfpt); 4069 remove_safepoints(phase, keep_one_sfpt); 4070 4071 // Look for induction variables 4072 phase->replace_parallel_iv(this); 4073 } else if (_head->is_LongCountedLoop() || 4074 phase->is_counted_loop(_head, loop, T_LONG)) { 4075 remove_safepoints(phase, true); 4076 } else { 4077 assert(!_head->is_Loop() || !_head->as_Loop()->is_loop_nest_inner_loop(), "transformation to counted loop should not fail"); 4078 if (_parent != nullptr && !_irreducible) { 4079 // Not a counted loop. Keep one safepoint. 4080 bool keep_one_sfpt = true; 4081 remove_safepoints(phase, keep_one_sfpt); 4082 } 4083 } 4084 4085 // Recursively 4086 assert(loop->_child != this || (loop->_head->as_Loop()->is_OuterStripMinedLoop() && _head->as_CountedLoop()->is_strip_mined()), "what kind of loop was added?"); 4087 assert(loop->_child != this || (loop->_child->_child == nullptr && loop->_child->_next == nullptr), "would miss some loops"); 4088 if (loop->_child && loop->_child != this) loop->_child->counted_loop(phase); 4089 if (loop->_next) loop->_next ->counted_loop(phase); 4090 } 4091 4092 4093 // The Estimated Loop Clone Size: 4094 // CloneFactor * (~112% * BodySize + BC) + CC + FanOutTerm, 4095 // where BC and CC are totally ad-hoc/magic "body" and "clone" constants, 4096 // respectively, used to ensure that the node usage estimates made are on the 4097 // safe side, for the most part. The FanOutTerm is an attempt to estimate the 4098 // possible additional/excessive nodes generated due to data and control flow 4099 // merging, for edges reaching outside the loop. 4100 uint IdealLoopTree::est_loop_clone_sz(uint factor) const { 4101 4102 precond(0 < factor && factor < 16); 4103 4104 uint const bc = 13; 4105 uint const cc = 17; 4106 uint const sz = _body.size() + (_body.size() + 7) / 2; 4107 uint estimate = factor * (sz + bc) + cc; 4108 4109 assert((estimate - cc) / factor == sz + bc, "overflow"); 4110 4111 return estimate + est_loop_flow_merge_sz(); 4112 } 4113 4114 // The Estimated Loop (full-) Unroll Size: 4115 // UnrollFactor * (~106% * BodySize) + CC + FanOutTerm, 4116 // where CC is a (totally) ad-hoc/magic "clone" constant, used to ensure that 4117 // node usage estimates made are on the safe side, for the most part. This is 4118 // a "light" version of the loop clone size calculation (above), based on the 4119 // assumption that most of the loop-construct overhead will be unraveled when 4120 // (fully) unrolled. Defined for unroll factors larger or equal to one (>=1), 4121 // including an overflow check and returning UINT_MAX in case of an overflow. 4122 uint IdealLoopTree::est_loop_unroll_sz(uint factor) const { 4123 4124 precond(factor > 0); 4125 4126 // Take into account that after unroll conjoined heads and tails will fold. 4127 uint const b0 = _body.size() - EMPTY_LOOP_SIZE; 4128 uint const cc = 7; 4129 uint const sz = b0 + (b0 + 15) / 16; 4130 uint estimate = factor * sz + cc; 4131 4132 if ((estimate - cc) / factor != sz) { 4133 return UINT_MAX; 4134 } 4135 4136 return estimate + est_loop_flow_merge_sz(); 4137 } 4138 4139 // Estimate the growth effect (in nodes) of merging control and data flow when 4140 // cloning a loop body, based on the amount of control and data flow reaching 4141 // outside of the (current) loop body. 4142 uint IdealLoopTree::est_loop_flow_merge_sz() const { 4143 4144 uint ctrl_edge_out_cnt = 0; 4145 uint data_edge_out_cnt = 0; 4146 4147 for (uint i = 0; i < _body.size(); i++) { 4148 Node* node = _body.at(i); 4149 uint outcnt = node->outcnt(); 4150 4151 for (uint k = 0; k < outcnt; k++) { 4152 Node* out = node->raw_out(k); 4153 if (out == nullptr) continue; 4154 if (out->is_CFG()) { 4155 if (!is_member(_phase->get_loop(out))) { 4156 ctrl_edge_out_cnt++; 4157 } 4158 } else if (_phase->has_ctrl(out)) { 4159 Node* ctrl = _phase->get_ctrl(out); 4160 assert(ctrl != nullptr, "must be"); 4161 assert(ctrl->is_CFG(), "must be"); 4162 if (!is_member(_phase->get_loop(ctrl))) { 4163 data_edge_out_cnt++; 4164 } 4165 } 4166 } 4167 } 4168 // Use data and control count (x2.0) in estimate iff both are > 0. This is 4169 // a rather pessimistic estimate for the most part, in particular for some 4170 // complex loops, but still not enough to capture all loops. 4171 if (ctrl_edge_out_cnt > 0 && data_edge_out_cnt > 0) { 4172 return 2 * (ctrl_edge_out_cnt + data_edge_out_cnt); 4173 } 4174 return 0; 4175 } 4176 4177 #ifndef PRODUCT 4178 //------------------------------dump_head-------------------------------------- 4179 // Dump 1 liner for loop header info 4180 void IdealLoopTree::dump_head() { 4181 tty->sp(2 * _nest); 4182 tty->print("Loop: N%d/N%d ", _head->_idx, _tail->_idx); 4183 if (_irreducible) tty->print(" IRREDUCIBLE"); 4184 Node* entry = _head->is_Loop() ? _head->as_Loop()->skip_strip_mined(-1)->in(LoopNode::EntryControl) 4185 : _head->in(LoopNode::EntryControl); 4186 const Predicates predicates(entry); 4187 if (predicates.loop_limit_check_predicate_block()->is_non_empty()) { 4188 tty->print(" limit_check"); 4189 } 4190 if (UseProfiledLoopPredicate && predicates.profiled_loop_predicate_block()->is_non_empty()) { 4191 tty->print(" profile_predicated"); 4192 } 4193 if (UseLoopPredicate && predicates.loop_predicate_block()->is_non_empty()) { 4194 tty->print(" predicated"); 4195 } 4196 if (_head->is_CountedLoop()) { 4197 CountedLoopNode *cl = _head->as_CountedLoop(); 4198 tty->print(" counted"); 4199 4200 Node* init_n = cl->init_trip(); 4201 if (init_n != nullptr && init_n->is_Con()) 4202 tty->print(" [%d,", cl->init_trip()->get_int()); 4203 else 4204 tty->print(" [int,"); 4205 Node* limit_n = cl->limit(); 4206 if (limit_n != nullptr && limit_n->is_Con()) 4207 tty->print("%d),", cl->limit()->get_int()); 4208 else 4209 tty->print("int),"); 4210 int stride_con = cl->stride_con(); 4211 if (stride_con > 0) tty->print("+"); 4212 tty->print("%d", stride_con); 4213 4214 tty->print(" (%0.f iters) ", cl->profile_trip_cnt()); 4215 4216 if (cl->is_pre_loop ()) tty->print(" pre" ); 4217 if (cl->is_main_loop()) tty->print(" main"); 4218 if (cl->is_post_loop()) tty->print(" post"); 4219 if (cl->is_vectorized_loop()) tty->print(" vector"); 4220 if (range_checks_present()) tty->print(" rc "); 4221 } 4222 if (_has_call) tty->print(" has_call"); 4223 if (_has_sfpt) tty->print(" has_sfpt"); 4224 if (_rce_candidate) tty->print(" rce"); 4225 if (_safepts != nullptr && _safepts->size() > 0) { 4226 tty->print(" sfpts={"); _safepts->dump_simple(); tty->print(" }"); 4227 } 4228 if (_required_safept != nullptr && _required_safept->size() > 0) { 4229 tty->print(" req={"); _required_safept->dump_simple(); tty->print(" }"); 4230 } 4231 if (Verbose) { 4232 tty->print(" body={"); _body.dump_simple(); tty->print(" }"); 4233 } 4234 if (_head->is_Loop() && _head->as_Loop()->is_strip_mined()) { 4235 tty->print(" strip_mined"); 4236 } 4237 tty->cr(); 4238 } 4239 4240 //------------------------------dump------------------------------------------- 4241 // Dump loops by loop tree 4242 void IdealLoopTree::dump() { 4243 dump_head(); 4244 if (_child) _child->dump(); 4245 if (_next) _next ->dump(); 4246 } 4247 4248 #endif 4249 4250 static void log_loop_tree_helper(IdealLoopTree* root, IdealLoopTree* loop, CompileLog* log) { 4251 if (loop == root) { 4252 if (loop->_child != nullptr) { 4253 log->begin_head("loop_tree"); 4254 log->end_head(); 4255 log_loop_tree_helper(root, loop->_child, log); 4256 log->tail("loop_tree"); 4257 assert(loop->_next == nullptr, "what?"); 4258 } 4259 } else if (loop != nullptr) { 4260 Node* head = loop->_head; 4261 log->begin_head("loop idx='%d'", head->_idx); 4262 if (loop->_irreducible) log->print(" irreducible='1'"); 4263 if (head->is_Loop()) { 4264 if (head->as_Loop()->is_inner_loop()) log->print(" inner_loop='1'"); 4265 if (head->as_Loop()->is_partial_peel_loop()) log->print(" partial_peel_loop='1'"); 4266 } else if (head->is_CountedLoop()) { 4267 CountedLoopNode* cl = head->as_CountedLoop(); 4268 if (cl->is_pre_loop()) log->print(" pre_loop='%d'", cl->main_idx()); 4269 if (cl->is_main_loop()) log->print(" main_loop='%d'", cl->_idx); 4270 if (cl->is_post_loop()) log->print(" post_loop='%d'", cl->main_idx()); 4271 } 4272 log->end_head(); 4273 log_loop_tree_helper(root, loop->_child, log); 4274 log->tail("loop"); 4275 log_loop_tree_helper(root, loop->_next, log); 4276 } 4277 } 4278 4279 void PhaseIdealLoop::log_loop_tree() { 4280 if (C->log() != nullptr) { 4281 log_loop_tree_helper(_ltree_root, _ltree_root, C->log()); 4282 } 4283 } 4284 4285 // Eliminate all Parse and Template Assertion Predicates that are not associated with a loop anymore. The eliminated 4286 // predicates will be removed during the next round of IGVN. 4287 void PhaseIdealLoop::eliminate_useless_predicates() { 4288 if (C->parse_predicate_count() == 0 && C->template_assertion_predicate_count() == 0) { 4289 return; // No predicates left. 4290 } 4291 4292 eliminate_useless_parse_predicates(); 4293 eliminate_useless_template_assertion_predicates(); 4294 } 4295 4296 // Eliminate all Parse Predicates that do not belong to a loop anymore by marking them useless. These will be removed 4297 // during the next round of IGVN. 4298 void PhaseIdealLoop::eliminate_useless_parse_predicates() { 4299 mark_all_parse_predicates_useless(); 4300 if (C->has_loops()) { 4301 mark_loop_associated_parse_predicates_useful(); 4302 } 4303 add_useless_parse_predicates_to_igvn_worklist(); 4304 } 4305 4306 void PhaseIdealLoop::mark_all_parse_predicates_useless() const { 4307 for (int i = 0; i < C->parse_predicate_count(); i++) { 4308 C->parse_predicate(i)->mark_useless(); 4309 } 4310 } 4311 4312 void PhaseIdealLoop::mark_loop_associated_parse_predicates_useful() { 4313 for (LoopTreeIterator iterator(_ltree_root); !iterator.done(); iterator.next()) { 4314 IdealLoopTree* loop = iterator.current(); 4315 if (loop->can_apply_loop_predication()) { 4316 mark_useful_parse_predicates_for_loop(loop); 4317 } 4318 } 4319 } 4320 4321 void PhaseIdealLoop::mark_useful_parse_predicates_for_loop(IdealLoopTree* loop) { 4322 Node* entry = loop->_head->as_Loop()->skip_strip_mined()->in(LoopNode::EntryControl); 4323 const Predicates predicates(entry); 4324 ParsePredicateIterator iterator(predicates); 4325 while (iterator.has_next()) { 4326 iterator.next()->mark_useful(); 4327 } 4328 } 4329 4330 void PhaseIdealLoop::add_useless_parse_predicates_to_igvn_worklist() { 4331 for (int i = 0; i < C->parse_predicate_count(); i++) { 4332 ParsePredicateNode* parse_predicate_node = C->parse_predicate(i); 4333 if (parse_predicate_node->is_useless()) { 4334 _igvn._worklist.push(parse_predicate_node); 4335 } 4336 } 4337 } 4338 4339 4340 // Eliminate all Template Assertion Predicates that do not belong to their originally associated loop anymore by 4341 // replacing the Opaque4 node of the If node with true. These nodes will be removed during the next round of IGVN. 4342 void PhaseIdealLoop::eliminate_useless_template_assertion_predicates() { 4343 Unique_Node_List useful_predicates; 4344 if (C->has_loops()) { 4345 collect_useful_template_assertion_predicates(useful_predicates); 4346 } 4347 eliminate_useless_template_assertion_predicates(useful_predicates); 4348 } 4349 4350 void PhaseIdealLoop::collect_useful_template_assertion_predicates(Unique_Node_List& useful_predicates) { 4351 for (LoopTreeIterator iterator(_ltree_root); !iterator.done(); iterator.next()) { 4352 IdealLoopTree* loop = iterator.current(); 4353 if (loop->can_apply_loop_predication()) { 4354 collect_useful_template_assertion_predicates_for_loop(loop, useful_predicates); 4355 } 4356 } 4357 } 4358 4359 void PhaseIdealLoop::collect_useful_template_assertion_predicates_for_loop(IdealLoopTree* loop, 4360 Unique_Node_List &useful_predicates) { 4361 Node* entry = loop->_head->as_Loop()->skip_strip_mined()->in(LoopNode::EntryControl); 4362 const Predicates predicates(entry); 4363 if (UseProfiledLoopPredicate) { 4364 const PredicateBlock* profiled_loop_predicate_block = predicates.profiled_loop_predicate_block(); 4365 if (profiled_loop_predicate_block->has_parse_predicate()) { 4366 IfProjNode* parse_predicate_proj = profiled_loop_predicate_block->parse_predicate_success_proj(); 4367 get_assertion_predicates(parse_predicate_proj, useful_predicates, true); 4368 } 4369 } 4370 4371 if (UseLoopPredicate) { 4372 const PredicateBlock* loop_predicate_block = predicates.loop_predicate_block(); 4373 if (loop_predicate_block->has_parse_predicate()) { 4374 IfProjNode* parse_predicate_proj = loop_predicate_block->parse_predicate_success_proj(); 4375 get_assertion_predicates(parse_predicate_proj, useful_predicates, true); 4376 } 4377 } 4378 } 4379 4380 void PhaseIdealLoop::eliminate_useless_template_assertion_predicates(Unique_Node_List& useful_predicates) { 4381 for (int i = C->template_assertion_predicate_count(); i > 0; i--) { 4382 Node* opaque4 = C->template_assertion_predicate_opaq_node(i - 1); 4383 assert(opaque4->Opcode() == Op_Opaque4, "must be"); 4384 if (!useful_predicates.member(opaque4)) { // not in the useful list 4385 _igvn.replace_node(opaque4, opaque4->in(2)); 4386 } 4387 } 4388 } 4389 4390 // If a post or main loop is removed due to an assert predicate, the opaque that guards the loop is not needed anymore 4391 void PhaseIdealLoop::eliminate_useless_zero_trip_guard() { 4392 if (_zero_trip_guard_opaque_nodes.size() == 0) { 4393 return; 4394 } 4395 Unique_Node_List useful_zero_trip_guard_opaques_nodes; 4396 for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) { 4397 IdealLoopTree* lpt = iter.current(); 4398 if (lpt->_child == nullptr && lpt->is_counted()) { 4399 CountedLoopNode* head = lpt->_head->as_CountedLoop(); 4400 Node* opaque = head->is_canonical_loop_entry(); 4401 if (opaque != nullptr) { 4402 useful_zero_trip_guard_opaques_nodes.push(opaque); 4403 } 4404 } 4405 } 4406 for (uint i = 0; i < _zero_trip_guard_opaque_nodes.size(); ++i) { 4407 OpaqueZeroTripGuardNode* opaque = ((OpaqueZeroTripGuardNode*)_zero_trip_guard_opaque_nodes.at(i)); 4408 DEBUG_ONLY(CountedLoopNode* guarded_loop = opaque->guarded_loop()); 4409 if (!useful_zero_trip_guard_opaques_nodes.member(opaque)) { 4410 IfNode* iff = opaque->if_node(); 4411 IdealLoopTree* loop = get_loop(iff); 4412 while (loop != _ltree_root && loop != nullptr) { 4413 loop = loop->_parent; 4414 } 4415 if (loop == nullptr) { 4416 // unreachable from _ltree_root: zero trip guard is in a newly discovered infinite loop. 4417 // We can't tell if the opaque node is useful or not 4418 assert(guarded_loop == nullptr || guarded_loop->is_in_infinite_subgraph(), ""); 4419 } else { 4420 assert(guarded_loop == nullptr, ""); 4421 this->_igvn.replace_node(opaque, opaque->in(1)); 4422 } 4423 } else { 4424 assert(guarded_loop != nullptr, ""); 4425 } 4426 } 4427 } 4428 4429 //------------------------process_expensive_nodes----------------------------- 4430 // Expensive nodes have their control input set to prevent the GVN 4431 // from commoning them and as a result forcing the resulting node to 4432 // be in a more frequent path. Use CFG information here, to change the 4433 // control inputs so that some expensive nodes can be commoned while 4434 // not executed more frequently. 4435 bool PhaseIdealLoop::process_expensive_nodes() { 4436 assert(OptimizeExpensiveOps, "optimization off?"); 4437 4438 // Sort nodes to bring similar nodes together 4439 C->sort_expensive_nodes(); 4440 4441 bool progress = false; 4442 4443 for (int i = 0; i < C->expensive_count(); ) { 4444 Node* n = C->expensive_node(i); 4445 int start = i; 4446 // Find nodes similar to n 4447 i++; 4448 for (; i < C->expensive_count() && Compile::cmp_expensive_nodes(n, C->expensive_node(i)) == 0; i++); 4449 int end = i; 4450 // And compare them two by two 4451 for (int j = start; j < end; j++) { 4452 Node* n1 = C->expensive_node(j); 4453 if (is_node_unreachable(n1)) { 4454 continue; 4455 } 4456 for (int k = j+1; k < end; k++) { 4457 Node* n2 = C->expensive_node(k); 4458 if (is_node_unreachable(n2)) { 4459 continue; 4460 } 4461 4462 assert(n1 != n2, "should be pair of nodes"); 4463 4464 Node* c1 = n1->in(0); 4465 Node* c2 = n2->in(0); 4466 4467 Node* parent_c1 = c1; 4468 Node* parent_c2 = c2; 4469 4470 // The call to get_early_ctrl_for_expensive() moves the 4471 // expensive nodes up but stops at loops that are in a if 4472 // branch. See whether we can exit the loop and move above the 4473 // If. 4474 if (c1->is_Loop()) { 4475 parent_c1 = c1->in(1); 4476 } 4477 if (c2->is_Loop()) { 4478 parent_c2 = c2->in(1); 4479 } 4480 4481 if (parent_c1 == parent_c2) { 4482 _igvn._worklist.push(n1); 4483 _igvn._worklist.push(n2); 4484 continue; 4485 } 4486 4487 // Look for identical expensive node up the dominator chain. 4488 if (is_dominator(c1, c2)) { 4489 c2 = c1; 4490 } else if (is_dominator(c2, c1)) { 4491 c1 = c2; 4492 } else if (parent_c1->is_Proj() && parent_c1->in(0)->is_If() && 4493 parent_c2->is_Proj() && parent_c1->in(0) == parent_c2->in(0)) { 4494 // Both branches have the same expensive node so move it up 4495 // before the if. 4496 c1 = c2 = idom(parent_c1->in(0)); 4497 } 4498 // Do the actual moves 4499 if (n1->in(0) != c1) { 4500 _igvn.replace_input_of(n1, 0, c1); 4501 progress = true; 4502 } 4503 if (n2->in(0) != c2) { 4504 _igvn.replace_input_of(n2, 0, c2); 4505 progress = true; 4506 } 4507 } 4508 } 4509 } 4510 4511 return progress; 4512 } 4513 4514 #ifdef ASSERT 4515 // Goes over all children of the root of the loop tree. Check if any of them have a path 4516 // down to Root, that does not go via a NeverBranch exit. 4517 bool PhaseIdealLoop::only_has_infinite_loops() { 4518 ResourceMark rm; 4519 Unique_Node_List worklist; 4520 // start traversal at all loop heads of first-level loops 4521 for (IdealLoopTree* l = _ltree_root->_child; l != nullptr; l = l->_next) { 4522 Node* head = l->_head; 4523 assert(head->is_Region(), ""); 4524 worklist.push(head); 4525 } 4526 return RegionNode::are_all_nodes_in_infinite_subgraph(worklist); 4527 } 4528 #endif 4529 4530 4531 //============================================================================= 4532 //----------------------------build_and_optimize------------------------------- 4533 // Create a PhaseLoop. Build the ideal Loop tree. Map each Ideal Node to 4534 // its corresponding LoopNode. If 'optimize' is true, do some loop cleanups. 4535 void PhaseIdealLoop::build_and_optimize() { 4536 assert(!C->post_loop_opts_phase(), "no loop opts allowed"); 4537 4538 bool do_split_ifs = (_mode == LoopOptsDefault); 4539 bool skip_loop_opts = (_mode == LoopOptsNone); 4540 bool do_max_unroll = (_mode == LoopOptsMaxUnroll); 4541 4542 4543 int old_progress = C->major_progress(); 4544 uint orig_worklist_size = _igvn._worklist.size(); 4545 4546 // Reset major-progress flag for the driver's heuristics 4547 C->clear_major_progress(); 4548 4549 #ifndef PRODUCT 4550 // Capture for later assert 4551 uint unique = C->unique(); 4552 _loop_invokes++; 4553 _loop_work += unique; 4554 #endif 4555 4556 // True if the method has at least 1 irreducible loop 4557 _has_irreducible_loops = false; 4558 4559 _created_loop_node = false; 4560 4561 VectorSet visited; 4562 // Pre-grow the mapping from Nodes to IdealLoopTrees. 4563 _loop_or_ctrl.map(C->unique(), nullptr); 4564 memset(_loop_or_ctrl.adr(), 0, wordSize * C->unique()); 4565 4566 // Pre-build the top-level outermost loop tree entry 4567 _ltree_root = new IdealLoopTree( this, C->root(), C->root() ); 4568 // Do not need a safepoint at the top level 4569 _ltree_root->_has_sfpt = 1; 4570 4571 // Initialize Dominators. 4572 // Checked in clone_loop_predicate() during beautify_loops(). 4573 _idom_size = 0; 4574 _idom = nullptr; 4575 _dom_depth = nullptr; 4576 _dom_stk = nullptr; 4577 4578 // Empty pre-order array 4579 allocate_preorders(); 4580 4581 // Build a loop tree on the fly. Build a mapping from CFG nodes to 4582 // IdealLoopTree entries. Data nodes are NOT walked. 4583 build_loop_tree(); 4584 // Check for bailout, and return 4585 if (C->failing()) { 4586 return; 4587 } 4588 4589 // Verify that the has_loops() flag set at parse time is consistent 4590 // with the just built loop tree. With infinite loops, it could be 4591 // that one pass of loop opts only finds infinite loops, clears the 4592 // has_loops() flag but adds NeverBranch nodes so the next loop opts 4593 // verification pass finds a non empty loop tree. When the back edge 4594 // is an exception edge, parsing doesn't set has_loops(). 4595 assert(_ltree_root->_child == nullptr || C->has_loops() || only_has_infinite_loops() || C->has_exception_backedge(), "parsing found no loops but there are some"); 4596 // No loops after all 4597 if( !_ltree_root->_child && !_verify_only ) C->set_has_loops(false); 4598 4599 // There should always be an outer loop containing the Root and Return nodes. 4600 // If not, we have a degenerate empty program. Bail out in this case. 4601 if (!has_node(C->root())) { 4602 if (!_verify_only) { 4603 C->clear_major_progress(); 4604 assert(false, "empty program detected during loop optimization"); 4605 C->record_method_not_compilable("empty program detected during loop optimization"); 4606 } 4607 return; 4608 } 4609 4610 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2(); 4611 // Nothing to do, so get out 4612 bool stop_early = !C->has_loops() && !skip_loop_opts && !do_split_ifs && !do_max_unroll && !_verify_me && 4613 !_verify_only && !bs->is_gc_specific_loop_opts_pass(_mode); 4614 bool do_expensive_nodes = C->should_optimize_expensive_nodes(_igvn); 4615 bool strip_mined_loops_expanded = bs->strip_mined_loops_expanded(_mode); 4616 if (stop_early && !do_expensive_nodes) { 4617 return; 4618 } 4619 4620 // Set loop nesting depth 4621 _ltree_root->set_nest( 0 ); 4622 4623 // Split shared headers and insert loop landing pads. 4624 // Do not bother doing this on the Root loop of course. 4625 if( !_verify_me && !_verify_only && _ltree_root->_child ) { 4626 C->print_method(PHASE_BEFORE_BEAUTIFY_LOOPS, 3); 4627 if( _ltree_root->_child->beautify_loops( this ) ) { 4628 // Re-build loop tree! 4629 _ltree_root->_child = nullptr; 4630 _loop_or_ctrl.clear(); 4631 reallocate_preorders(); 4632 build_loop_tree(); 4633 // Check for bailout, and return 4634 if (C->failing()) { 4635 return; 4636 } 4637 // Reset loop nesting depth 4638 _ltree_root->set_nest( 0 ); 4639 4640 C->print_method(PHASE_AFTER_BEAUTIFY_LOOPS, 3); 4641 } 4642 } 4643 4644 // Build Dominators for elision of null checks & loop finding. 4645 // Since nodes do not have a slot for immediate dominator, make 4646 // a persistent side array for that info indexed on node->_idx. 4647 _idom_size = C->unique(); 4648 _idom = NEW_RESOURCE_ARRAY( Node*, _idom_size ); 4649 _dom_depth = NEW_RESOURCE_ARRAY( uint, _idom_size ); 4650 _dom_stk = nullptr; // Allocated on demand in recompute_dom_depth 4651 memset( _dom_depth, 0, _idom_size * sizeof(uint) ); 4652 4653 Dominators(); 4654 4655 if (!_verify_only) { 4656 // As a side effect, Dominators removed any unreachable CFG paths 4657 // into RegionNodes. It doesn't do this test against Root, so 4658 // we do it here. 4659 for( uint i = 1; i < C->root()->req(); i++ ) { 4660 if (!_loop_or_ctrl[C->root()->in(i)->_idx]) { // Dead path into Root? 4661 _igvn.delete_input_of(C->root(), i); 4662 i--; // Rerun same iteration on compressed edges 4663 } 4664 } 4665 4666 // Given dominators, try to find inner loops with calls that must 4667 // always be executed (call dominates loop tail). These loops do 4668 // not need a separate safepoint. 4669 Node_List cisstack; 4670 _ltree_root->check_safepts(visited, cisstack); 4671 } 4672 4673 // Walk the DATA nodes and place into loops. Find earliest control 4674 // node. For CFG nodes, the _loop_or_ctrl array starts out and remains 4675 // holding the associated IdealLoopTree pointer. For DATA nodes, the 4676 // _loop_or_ctrl array holds the earliest legal controlling CFG node. 4677 4678 // Allocate stack with enough space to avoid frequent realloc 4679 int stack_size = (C->live_nodes() >> 1) + 16; // (live_nodes>>1)+16 from Java2D stats 4680 Node_Stack nstack(stack_size); 4681 4682 visited.clear(); 4683 Node_List worklist; 4684 // Don't need C->root() on worklist since 4685 // it will be processed among C->top() inputs 4686 worklist.push(C->top()); 4687 visited.set(C->top()->_idx); // Set C->top() as visited now 4688 build_loop_early( visited, worklist, nstack ); 4689 4690 // Given early legal placement, try finding counted loops. This placement 4691 // is good enough to discover most loop invariants. 4692 if (!_verify_me && !_verify_only && !strip_mined_loops_expanded) { 4693 _ltree_root->counted_loop( this ); 4694 } 4695 4696 // Find latest loop placement. Find ideal loop placement. 4697 visited.clear(); 4698 init_dom_lca_tags(); 4699 // Need C->root() on worklist when processing outs 4700 worklist.push(C->root()); 4701 NOT_PRODUCT( C->verify_graph_edges(); ) 4702 worklist.push(C->top()); 4703 build_loop_late( visited, worklist, nstack ); 4704 if (C->failing()) { return; } 4705 4706 if (_verify_only) { 4707 C->restore_major_progress(old_progress); 4708 assert(C->unique() == unique, "verification _mode made Nodes? ? ?"); 4709 assert(_igvn._worklist.size() == orig_worklist_size, "shouldn't push anything"); 4710 return; 4711 } 4712 4713 // clear out the dead code after build_loop_late 4714 while (_deadlist.size()) { 4715 _igvn.remove_globally_dead_node(_deadlist.pop()); 4716 } 4717 4718 eliminate_useless_zero_trip_guard(); 4719 4720 if (stop_early) { 4721 assert(do_expensive_nodes, "why are we here?"); 4722 if (process_expensive_nodes()) { 4723 // If we made some progress when processing expensive nodes then 4724 // the IGVN may modify the graph in a way that will allow us to 4725 // make some more progress: we need to try processing expensive 4726 // nodes again. 4727 C->set_major_progress(); 4728 } 4729 return; 4730 } 4731 4732 // Some parser-inserted loop predicates could never be used by loop 4733 // predication or they were moved away from loop during some optimizations. 4734 // For example, peeling. Eliminate them before next loop optimizations. 4735 eliminate_useless_predicates(); 4736 4737 #ifndef PRODUCT 4738 C->verify_graph_edges(); 4739 if (_verify_me) { // Nested verify pass? 4740 // Check to see if the verify _mode is broken 4741 assert(C->unique() == unique, "non-optimize _mode made Nodes? ? ?"); 4742 return; 4743 } 4744 DEBUG_ONLY( if (VerifyLoopOptimizations) { verify(); } ); 4745 if (TraceLoopOpts && C->has_loops()) { 4746 _ltree_root->dump(); 4747 } 4748 #endif 4749 4750 if (skip_loop_opts) { 4751 C->restore_major_progress(old_progress); 4752 return; 4753 } 4754 4755 if (do_max_unroll) { 4756 for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) { 4757 IdealLoopTree* lpt = iter.current(); 4758 if (lpt->is_innermost() && lpt->_allow_optimizations && !lpt->_has_call && lpt->is_counted()) { 4759 lpt->compute_trip_count(this); 4760 if (!lpt->do_one_iteration_loop(this) && 4761 !lpt->do_remove_empty_loop(this)) { 4762 AutoNodeBudget node_budget(this); 4763 if (lpt->_head->as_CountedLoop()->is_normal_loop() && 4764 lpt->policy_maximally_unroll(this)) { 4765 memset( worklist.adr(), 0, worklist.max()*sizeof(Node*) ); 4766 do_maximally_unroll(lpt, worklist); 4767 } 4768 } 4769 } 4770 } 4771 4772 C->restore_major_progress(old_progress); 4773 return; 4774 } 4775 4776 if (bs->optimize_loops(this, _mode, visited, nstack, worklist)) { 4777 return; 4778 } 4779 4780 if (ReassociateInvariants && !C->major_progress()) { 4781 // Reassociate invariants and prep for split_thru_phi 4782 for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) { 4783 IdealLoopTree* lpt = iter.current(); 4784 if (!lpt->is_loop()) { 4785 continue; 4786 } 4787 Node* head = lpt->_head; 4788 if (!head->is_BaseCountedLoop() || !lpt->is_innermost()) continue; 4789 4790 // check for vectorized loops, any reassociation of invariants was already done 4791 if (head->is_CountedLoop()) { 4792 if (head->as_CountedLoop()->is_unroll_only()) { 4793 continue; 4794 } else { 4795 AutoNodeBudget node_budget(this); 4796 lpt->reassociate_invariants(this); 4797 } 4798 } 4799 // Because RCE opportunities can be masked by split_thru_phi, 4800 // look for RCE candidates and inhibit split_thru_phi 4801 // on just their loop-phi's for this pass of loop opts 4802 if (SplitIfBlocks && do_split_ifs && 4803 head->as_BaseCountedLoop()->is_valid_counted_loop(head->as_BaseCountedLoop()->bt()) && 4804 (lpt->policy_range_check(this, true, T_LONG) || 4805 (head->is_CountedLoop() && lpt->policy_range_check(this, true, T_INT)))) { 4806 lpt->_rce_candidate = 1; // = true 4807 } 4808 } 4809 } 4810 4811 // Check for aggressive application of split-if and other transforms 4812 // that require basic-block info (like cloning through Phi's) 4813 if (!C->major_progress() && SplitIfBlocks && do_split_ifs) { 4814 visited.clear(); 4815 split_if_with_blocks( visited, nstack); 4816 DEBUG_ONLY( if (VerifyLoopOptimizations) { verify(); } ); 4817 } 4818 4819 if (!C->major_progress() && do_expensive_nodes && process_expensive_nodes()) { 4820 C->set_major_progress(); 4821 } 4822 4823 // Perform loop predication before iteration splitting 4824 if (UseLoopPredicate && C->has_loops() && !C->major_progress() && (C->parse_predicate_count() > 0)) { 4825 _ltree_root->_child->loop_predication(this); 4826 } 4827 4828 if (OptimizeFill && UseLoopPredicate && C->has_loops() && !C->major_progress()) { 4829 if (do_intrinsify_fill()) { 4830 C->set_major_progress(); 4831 } 4832 } 4833 4834 // Perform iteration-splitting on inner loops. Split iterations to avoid 4835 // range checks or one-shot null checks. 4836 4837 // If split-if's didn't hack the graph too bad (no CFG changes) 4838 // then do loop opts. 4839 if (C->has_loops() && !C->major_progress()) { 4840 memset( worklist.adr(), 0, worklist.max()*sizeof(Node*) ); 4841 _ltree_root->_child->iteration_split( this, worklist ); 4842 // No verify after peeling! GCM has hoisted code out of the loop. 4843 // After peeling, the hoisted code could sink inside the peeled area. 4844 // The peeling code does not try to recompute the best location for 4845 // all the code before the peeled area, so the verify pass will always 4846 // complain about it. 4847 } 4848 4849 // Check for bailout, and return 4850 if (C->failing()) { 4851 return; 4852 } 4853 4854 // Do verify graph edges in any case 4855 NOT_PRODUCT( C->verify_graph_edges(); ); 4856 4857 if (!do_split_ifs) { 4858 // We saw major progress in Split-If to get here. We forced a 4859 // pass with unrolling and not split-if, however more split-if's 4860 // might make progress. If the unrolling didn't make progress 4861 // then the major-progress flag got cleared and we won't try 4862 // another round of Split-If. In particular the ever-common 4863 // instance-of/check-cast pattern requires at least 2 rounds of 4864 // Split-If to clear out. 4865 C->set_major_progress(); 4866 } 4867 4868 // Repeat loop optimizations if new loops were seen 4869 if (created_loop_node()) { 4870 C->set_major_progress(); 4871 } 4872 4873 // Keep loop predicates and perform optimizations with them 4874 // until no more loop optimizations could be done. 4875 // After that switch predicates off and do more loop optimizations. 4876 if (!C->major_progress() && (C->parse_predicate_count() > 0)) { 4877 C->mark_parse_predicate_nodes_useless(_igvn); 4878 assert(C->parse_predicate_count() == 0, "should be zero now"); 4879 if (TraceLoopOpts) { 4880 tty->print_cr("PredicatesOff"); 4881 } 4882 C->set_major_progress(); 4883 } 4884 4885 // Auto-vectorize main-loop 4886 if (C->do_superword() && C->has_loops() && !C->major_progress()) { 4887 Compile::TracePhase tp("autoVectorize", &timers[_t_autoVectorize]); 4888 4889 // Shared data structures for all AutoVectorizations, to reduce allocations 4890 // of large arrays. 4891 VSharedData vshared; 4892 for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) { 4893 IdealLoopTree* lpt = iter.current(); 4894 AutoVectorizeStatus status = auto_vectorize(lpt, vshared); 4895 4896 if (status == AutoVectorizeStatus::TriedAndFailed) { 4897 // We tried vectorization, but failed. From now on only unroll the loop. 4898 CountedLoopNode* cl = lpt->_head->as_CountedLoop(); 4899 if (cl->has_passed_slp()) { 4900 C->set_major_progress(); 4901 cl->set_notpassed_slp(); 4902 cl->mark_do_unroll_only(); 4903 } 4904 } 4905 } 4906 } 4907 4908 // Move UnorderedReduction out of counted loop. Can be introduced by AutoVectorization. 4909 if (C->has_loops() && !C->major_progress()) { 4910 for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) { 4911 IdealLoopTree* lpt = iter.current(); 4912 if (lpt->is_counted() && lpt->is_innermost()) { 4913 move_unordered_reduction_out_of_loop(lpt); 4914 } 4915 } 4916 } 4917 } 4918 4919 #ifndef PRODUCT 4920 //------------------------------print_statistics------------------------------- 4921 int PhaseIdealLoop::_loop_invokes=0;// Count of PhaseIdealLoop invokes 4922 int PhaseIdealLoop::_loop_work=0; // Sum of PhaseIdealLoop x unique 4923 volatile int PhaseIdealLoop::_long_loop_candidates=0; // Number of long loops seen 4924 volatile int PhaseIdealLoop::_long_loop_nests=0; // Number of long loops successfully transformed to a nest 4925 volatile int PhaseIdealLoop::_long_loop_counted_loops=0; // Number of long loops successfully transformed to a counted loop 4926 void PhaseIdealLoop::print_statistics() { 4927 tty->print_cr("PhaseIdealLoop=%d, sum _unique=%d, long loops=%d/%d/%d", _loop_invokes, _loop_work, _long_loop_counted_loops, _long_loop_nests, _long_loop_candidates); 4928 } 4929 #endif 4930 4931 #ifdef ASSERT 4932 // Build a verify-only PhaseIdealLoop, and see that it agrees with "this". 4933 void PhaseIdealLoop::verify() const { 4934 ResourceMark rm; 4935 int old_progress = C->major_progress(); 4936 bool success = true; 4937 4938 PhaseIdealLoop phase_verify(_igvn, this); 4939 if (C->failing()) return; 4940 4941 // Verify ctrl and idom of every node. 4942 success &= verify_idom_and_nodes(C->root(), &phase_verify); 4943 4944 // Verify loop-tree. 4945 success &= _ltree_root->verify_tree(phase_verify._ltree_root); 4946 4947 assert(success, "VerifyLoopOptimizations failed"); 4948 4949 // Major progress was cleared by creating a verify version of PhaseIdealLoop. 4950 C->restore_major_progress(old_progress); 4951 } 4952 4953 // Perform a BFS starting at n, through all inputs. 4954 // Call verify_idom and verify_node on all nodes of BFS traversal. 4955 bool PhaseIdealLoop::verify_idom_and_nodes(Node* root, const PhaseIdealLoop* phase_verify) const { 4956 Unique_Node_List worklist; 4957 worklist.push(root); 4958 bool success = true; 4959 for (uint i = 0; i < worklist.size(); i++) { 4960 Node* n = worklist.at(i); 4961 // process node 4962 success &= verify_idom(n, phase_verify); 4963 success &= verify_loop_ctrl(n, phase_verify); 4964 // visit inputs 4965 for (uint j = 0; j < n->req(); j++) { 4966 if (n->in(j) != nullptr) { 4967 worklist.push(n->in(j)); 4968 } 4969 } 4970 } 4971 return success; 4972 } 4973 4974 // Verify dominator structure (IDOM). 4975 bool PhaseIdealLoop::verify_idom(Node* n, const PhaseIdealLoop* phase_verify) const { 4976 // Verify IDOM for all CFG nodes (except root). 4977 if (!n->is_CFG() || n->is_Root()) { 4978 return true; // pass 4979 } 4980 4981 if (n->_idx >= _idom_size) { 4982 tty->print("CFG Node with no idom: "); 4983 n->dump(); 4984 return false; // fail 4985 } 4986 4987 Node* id = idom_no_update(n); 4988 Node* id_verify = phase_verify->idom_no_update(n); 4989 if (id != id_verify) { 4990 tty->print("Mismatching idom for node: "); 4991 n->dump(); 4992 tty->print(" We have idom: "); 4993 id->dump(); 4994 tty->print(" Verify has idom: "); 4995 id_verify->dump(); 4996 tty->cr(); 4997 return false; // fail 4998 } 4999 return true; // pass 5000 } 5001 5002 // Verify "_loop_or_ctrl": control and loop membership. 5003 // (0) _loop_or_ctrl[i] == nullptr -> node not reachable. 5004 // (1) has_ctrl -> check lowest bit. 1 -> data node. 0 -> ctrl node. 5005 // (2) has_ctrl true: get_ctrl_no_update returns ctrl of data node. 5006 // (3) has_ctrl false: get_loop_idx returns IdealLoopTree for ctrl node. 5007 bool PhaseIdealLoop::verify_loop_ctrl(Node* n, const PhaseIdealLoop* phase_verify) const { 5008 const uint i = n->_idx; 5009 // The loop-tree was built from def to use (top-down). 5010 // The verification happens from use to def (bottom-up). 5011 // We may thus find nodes during verification that are not in the loop-tree. 5012 if (_loop_or_ctrl[i] == nullptr || phase_verify->_loop_or_ctrl[i] == nullptr) { 5013 if (_loop_or_ctrl[i] != nullptr || phase_verify->_loop_or_ctrl[i] != nullptr) { 5014 tty->print_cr("Was reachable in only one. this %d, verify %d.", 5015 _loop_or_ctrl[i] != nullptr, phase_verify->_loop_or_ctrl[i] != nullptr); 5016 n->dump(); 5017 return false; // fail 5018 } 5019 // Not reachable for both. 5020 return true; // pass 5021 } 5022 5023 if (n->is_CFG() == has_ctrl(n)) { 5024 tty->print_cr("Exactly one should be true: %d for is_CFG, %d for has_ctrl.", n->is_CFG(), has_ctrl(n)); 5025 n->dump(); 5026 return false; // fail 5027 } 5028 5029 if (has_ctrl(n) != phase_verify->has_ctrl(n)) { 5030 tty->print_cr("Mismatch has_ctrl: %d for this, %d for verify.", has_ctrl(n), phase_verify->has_ctrl(n)); 5031 n->dump(); 5032 return false; // fail 5033 } else if (has_ctrl(n)) { 5034 assert(phase_verify->has_ctrl(n), "sanity"); 5035 // n is a data node. 5036 // Verify that its ctrl is the same. 5037 5038 // Broken part of VerifyLoopOptimizations (A) 5039 // Reason: 5040 // BUG, wrong control set for example in 5041 // PhaseIdealLoop::split_if_with_blocks 5042 // at "set_ctrl(x, new_ctrl);" 5043 /* 5044 if( _loop_or_ctrl[i] != loop_verify->_loop_or_ctrl[i] && 5045 get_ctrl_no_update(n) != loop_verify->get_ctrl_no_update(n) ) { 5046 tty->print("Mismatched control setting for: "); 5047 n->dump(); 5048 if( fail++ > 10 ) return; 5049 Node *c = get_ctrl_no_update(n); 5050 tty->print("We have it as: "); 5051 if( c->in(0) ) c->dump(); 5052 else tty->print_cr("N%d",c->_idx); 5053 tty->print("Verify thinks: "); 5054 if( loop_verify->has_ctrl(n) ) 5055 loop_verify->get_ctrl_no_update(n)->dump(); 5056 else 5057 loop_verify->get_loop_idx(n)->dump(); 5058 tty->cr(); 5059 } 5060 */ 5061 return true; // pass 5062 } else { 5063 assert(!phase_verify->has_ctrl(n), "sanity"); 5064 // n is a ctrl node. 5065 // Verify that not has_ctrl, and that get_loop_idx is the same. 5066 5067 // Broken part of VerifyLoopOptimizations (B) 5068 // Reason: 5069 // NeverBranch node for example is added to loop outside its scope. 5070 // Once we run build_loop_tree again, it is added to the correct loop. 5071 /* 5072 if (!C->major_progress()) { 5073 // Loop selection can be messed up if we did a major progress 5074 // operation, like split-if. Do not verify in that case. 5075 IdealLoopTree *us = get_loop_idx(n); 5076 IdealLoopTree *them = loop_verify->get_loop_idx(n); 5077 if( us->_head != them->_head || us->_tail != them->_tail ) { 5078 tty->print("Unequals loops for: "); 5079 n->dump(); 5080 if( fail++ > 10 ) return; 5081 tty->print("We have it as: "); 5082 us->dump(); 5083 tty->print("Verify thinks: "); 5084 them->dump(); 5085 tty->cr(); 5086 } 5087 } 5088 */ 5089 return true; // pass 5090 } 5091 } 5092 5093 static int compare_tree(IdealLoopTree* const& a, IdealLoopTree* const& b) { 5094 assert(a != nullptr && b != nullptr, "must be"); 5095 return a->_head->_idx - b->_head->_idx; 5096 } 5097 5098 GrowableArray<IdealLoopTree*> IdealLoopTree::collect_sorted_children() const { 5099 GrowableArray<IdealLoopTree*> children; 5100 IdealLoopTree* child = _child; 5101 while (child != nullptr) { 5102 assert(child->_parent == this, "all must be children of this"); 5103 children.insert_sorted<compare_tree>(child); 5104 child = child->_next; 5105 } 5106 return children; 5107 } 5108 5109 // Verify that tree structures match. Because the CFG can change, siblings 5110 // within the loop tree can be reordered. We attempt to deal with that by 5111 // reordering the verify's loop tree if possible. 5112 bool IdealLoopTree::verify_tree(IdealLoopTree* loop_verify) const { 5113 assert(_head == loop_verify->_head, "mismatched loop head"); 5114 assert(this->_parent != nullptr || this->_next == nullptr, "is_root_loop implies has_no_sibling"); 5115 5116 // Collect the children 5117 GrowableArray<IdealLoopTree*> children = collect_sorted_children(); 5118 GrowableArray<IdealLoopTree*> children_verify = loop_verify->collect_sorted_children(); 5119 5120 bool success = true; 5121 5122 // Compare the two children lists 5123 for (int i = 0, j = 0; i < children.length() || j < children_verify.length(); ) { 5124 IdealLoopTree* child = nullptr; 5125 IdealLoopTree* child_verify = nullptr; 5126 // Read from both lists, if possible. 5127 if (i < children.length()) { 5128 child = children.at(i); 5129 } 5130 if (j < children_verify.length()) { 5131 child_verify = children_verify.at(j); 5132 } 5133 assert(child != nullptr || child_verify != nullptr, "must find at least one"); 5134 if (child != nullptr && child_verify != nullptr && child->_head != child_verify->_head) { 5135 // We found two non-equal children. Select the smaller one. 5136 if (child->_head->_idx < child_verify->_head->_idx) { 5137 child_verify = nullptr; 5138 } else { 5139 child = nullptr; 5140 } 5141 } 5142 // Process the two children, or potentially log the failure if we only found one. 5143 if (child_verify == nullptr) { 5144 if (child->_irreducible && Compile::current()->major_progress()) { 5145 // Irreducible loops can pick a different header (one of its entries). 5146 } else { 5147 tty->print_cr("We have a loop that verify does not have"); 5148 child->dump(); 5149 success = false; 5150 } 5151 i++; // step for this 5152 } else if (child == nullptr) { 5153 if (child_verify->_irreducible && Compile::current()->major_progress()) { 5154 // Irreducible loops can pick a different header (one of its entries). 5155 } else if (child_verify->_head->as_Region()->is_in_infinite_subgraph()) { 5156 // Infinite loops do not get attached to the loop-tree on their first visit. 5157 // "this" runs before "loop_verify". It is thus possible that we find the 5158 // infinite loop only for "child_verify". Only finding it with "child" would 5159 // mean that we lost it, which is not ok. 5160 } else { 5161 tty->print_cr("Verify has a loop that we do not have"); 5162 child_verify->dump(); 5163 success = false; 5164 } 5165 j++; // step for verify 5166 } else { 5167 assert(child->_head == child_verify->_head, "We have both and they are equal"); 5168 success &= child->verify_tree(child_verify); // Recursion 5169 i++; // step for this 5170 j++; // step for verify 5171 } 5172 } 5173 5174 // Broken part of VerifyLoopOptimizations (D) 5175 // Reason: 5176 // split_if has to update the _tail, if it is modified. But that is done by 5177 // checking to what loop the iff belongs to. That info can be wrong, and then 5178 // we do not update the _tail correctly. 5179 /* 5180 Node *tail = _tail; // Inline a non-updating version of 5181 while( !tail->in(0) ) // the 'tail()' call. 5182 tail = tail->in(1); 5183 assert( tail == loop->_tail, "mismatched loop tail" ); 5184 */ 5185 5186 if (_head->is_CountedLoop()) { 5187 CountedLoopNode *cl = _head->as_CountedLoop(); 5188 5189 Node* ctrl = cl->init_control(); 5190 Node* back = cl->back_control(); 5191 assert(ctrl != nullptr && ctrl->is_CFG(), "sane loop in-ctrl"); 5192 assert(back != nullptr && back->is_CFG(), "sane loop backedge"); 5193 cl->loopexit(); // assert implied 5194 } 5195 5196 // Broken part of VerifyLoopOptimizations (E) 5197 // Reason: 5198 // PhaseIdealLoop::split_thru_region creates new nodes for loop that are not added 5199 // to the loop body. Or maybe they are not added to the correct loop. 5200 // at "Node* x = n->clone();" 5201 /* 5202 // Innermost loops need to verify loop bodies, 5203 // but only if no 'major_progress' 5204 int fail = 0; 5205 if (!Compile::current()->major_progress() && _child == nullptr) { 5206 for( uint i = 0; i < _body.size(); i++ ) { 5207 Node *n = _body.at(i); 5208 if (n->outcnt() == 0) continue; // Ignore dead 5209 uint j; 5210 for( j = 0; j < loop->_body.size(); j++ ) 5211 if( loop->_body.at(j) == n ) 5212 break; 5213 if( j == loop->_body.size() ) { // Not found in loop body 5214 // Last ditch effort to avoid assertion: Its possible that we 5215 // have some users (so outcnt not zero) but are still dead. 5216 // Try to find from root. 5217 if (Compile::current()->root()->find(n->_idx)) { 5218 fail++; 5219 tty->print("We have that verify does not: "); 5220 n->dump(); 5221 } 5222 } 5223 } 5224 for( uint i2 = 0; i2 < loop->_body.size(); i2++ ) { 5225 Node *n = loop->_body.at(i2); 5226 if (n->outcnt() == 0) continue; // Ignore dead 5227 uint j; 5228 for( j = 0; j < _body.size(); j++ ) 5229 if( _body.at(j) == n ) 5230 break; 5231 if( j == _body.size() ) { // Not found in loop body 5232 // Last ditch effort to avoid assertion: Its possible that we 5233 // have some users (so outcnt not zero) but are still dead. 5234 // Try to find from root. 5235 if (Compile::current()->root()->find(n->_idx)) { 5236 fail++; 5237 tty->print("Verify has that we do not: "); 5238 n->dump(); 5239 } 5240 } 5241 } 5242 assert( !fail, "loop body mismatch" ); 5243 } 5244 */ 5245 return success; 5246 } 5247 #endif 5248 5249 //------------------------------set_idom--------------------------------------- 5250 void PhaseIdealLoop::set_idom(Node* d, Node* n, uint dom_depth) { 5251 uint idx = d->_idx; 5252 if (idx >= _idom_size) { 5253 uint newsize = next_power_of_2(idx); 5254 _idom = REALLOC_RESOURCE_ARRAY( Node*, _idom,_idom_size,newsize); 5255 _dom_depth = REALLOC_RESOURCE_ARRAY( uint, _dom_depth,_idom_size,newsize); 5256 memset( _dom_depth + _idom_size, 0, (newsize - _idom_size) * sizeof(uint) ); 5257 _idom_size = newsize; 5258 } 5259 _idom[idx] = n; 5260 _dom_depth[idx] = dom_depth; 5261 } 5262 5263 //------------------------------recompute_dom_depth--------------------------------------- 5264 // The dominator tree is constructed with only parent pointers. 5265 // This recomputes the depth in the tree by first tagging all 5266 // nodes as "no depth yet" marker. The next pass then runs up 5267 // the dom tree from each node marked "no depth yet", and computes 5268 // the depth on the way back down. 5269 void PhaseIdealLoop::recompute_dom_depth() { 5270 uint no_depth_marker = C->unique(); 5271 uint i; 5272 // Initialize depth to "no depth yet" and realize all lazy updates 5273 for (i = 0; i < _idom_size; i++) { 5274 // Only indices with a _dom_depth has a Node* or null (otherwise uninitialized). 5275 if (_dom_depth[i] > 0 && _idom[i] != nullptr) { 5276 _dom_depth[i] = no_depth_marker; 5277 5278 // heal _idom if it has a fwd mapping in _loop_or_ctrl 5279 if (_idom[i]->in(0) == nullptr) { 5280 idom(i); 5281 } 5282 } 5283 } 5284 if (_dom_stk == nullptr) { 5285 uint init_size = C->live_nodes() / 100; // Guess that 1/100 is a reasonable initial size. 5286 if (init_size < 10) init_size = 10; 5287 _dom_stk = new GrowableArray<uint>(init_size); 5288 } 5289 // Compute new depth for each node. 5290 for (i = 0; i < _idom_size; i++) { 5291 uint j = i; 5292 // Run up the dom tree to find a node with a depth 5293 while (_dom_depth[j] == no_depth_marker) { 5294 _dom_stk->push(j); 5295 j = _idom[j]->_idx; 5296 } 5297 // Compute the depth on the way back down this tree branch 5298 uint dd = _dom_depth[j] + 1; 5299 while (_dom_stk->length() > 0) { 5300 uint j = _dom_stk->pop(); 5301 _dom_depth[j] = dd; 5302 dd++; 5303 } 5304 } 5305 } 5306 5307 //------------------------------sort------------------------------------------- 5308 // Insert 'loop' into the existing loop tree. 'innermost' is a leaf of the 5309 // loop tree, not the root. 5310 IdealLoopTree *PhaseIdealLoop::sort( IdealLoopTree *loop, IdealLoopTree *innermost ) { 5311 if( !innermost ) return loop; // New innermost loop 5312 5313 int loop_preorder = get_preorder(loop->_head); // Cache pre-order number 5314 assert( loop_preorder, "not yet post-walked loop" ); 5315 IdealLoopTree **pp = &innermost; // Pointer to previous next-pointer 5316 IdealLoopTree *l = *pp; // Do I go before or after 'l'? 5317 5318 // Insert at start of list 5319 while( l ) { // Insertion sort based on pre-order 5320 if( l == loop ) return innermost; // Already on list! 5321 int l_preorder = get_preorder(l->_head); // Cache pre-order number 5322 assert( l_preorder, "not yet post-walked l" ); 5323 // Check header pre-order number to figure proper nesting 5324 if( loop_preorder > l_preorder ) 5325 break; // End of insertion 5326 // If headers tie (e.g., shared headers) check tail pre-order numbers. 5327 // Since I split shared headers, you'd think this could not happen. 5328 // BUT: I must first do the preorder numbering before I can discover I 5329 // have shared headers, so the split headers all get the same preorder 5330 // number as the RegionNode they split from. 5331 if( loop_preorder == l_preorder && 5332 get_preorder(loop->_tail) < get_preorder(l->_tail) ) 5333 break; // Also check for shared headers (same pre#) 5334 pp = &l->_parent; // Chain up list 5335 l = *pp; 5336 } 5337 // Link into list 5338 // Point predecessor to me 5339 *pp = loop; 5340 // Point me to successor 5341 IdealLoopTree *p = loop->_parent; 5342 loop->_parent = l; // Point me to successor 5343 if( p ) sort( p, innermost ); // Insert my parents into list as well 5344 return innermost; 5345 } 5346 5347 //------------------------------build_loop_tree-------------------------------- 5348 // I use a modified Vick/Tarjan algorithm. I need pre- and a post- visit 5349 // bits. The _loop_or_ctrl[] array is mapped by Node index and holds a null for 5350 // not-yet-pre-walked, pre-order # for pre-but-not-post-walked and holds the 5351 // tightest enclosing IdealLoopTree for post-walked. 5352 // 5353 // During my forward walk I do a short 1-layer lookahead to see if I can find 5354 // a loop backedge with that doesn't have any work on the backedge. This 5355 // helps me construct nested loops with shared headers better. 5356 // 5357 // Once I've done the forward recursion, I do the post-work. For each child 5358 // I check to see if there is a backedge. Backedges define a loop! I 5359 // insert an IdealLoopTree at the target of the backedge. 5360 // 5361 // During the post-work I also check to see if I have several children 5362 // belonging to different loops. If so, then this Node is a decision point 5363 // where control flow can choose to change loop nests. It is at this 5364 // decision point where I can figure out how loops are nested. At this 5365 // time I can properly order the different loop nests from my children. 5366 // Note that there may not be any backedges at the decision point! 5367 // 5368 // Since the decision point can be far removed from the backedges, I can't 5369 // order my loops at the time I discover them. Thus at the decision point 5370 // I need to inspect loop header pre-order numbers to properly nest my 5371 // loops. This means I need to sort my childrens' loops by pre-order. 5372 // The sort is of size number-of-control-children, which generally limits 5373 // it to size 2 (i.e., I just choose between my 2 target loops). 5374 void PhaseIdealLoop::build_loop_tree() { 5375 // Allocate stack of size C->live_nodes()/2 to avoid frequent realloc 5376 GrowableArray <Node *> bltstack(C->live_nodes() >> 1); 5377 Node *n = C->root(); 5378 bltstack.push(n); 5379 int pre_order = 1; 5380 int stack_size; 5381 5382 while ( ( stack_size = bltstack.length() ) != 0 ) { 5383 n = bltstack.top(); // Leave node on stack 5384 if ( !is_visited(n) ) { 5385 // ---- Pre-pass Work ---- 5386 // Pre-walked but not post-walked nodes need a pre_order number. 5387 5388 set_preorder_visited( n, pre_order ); // set as visited 5389 5390 // ---- Scan over children ---- 5391 // Scan first over control projections that lead to loop headers. 5392 // This helps us find inner-to-outer loops with shared headers better. 5393 5394 // Scan children's children for loop headers. 5395 for ( int i = n->outcnt() - 1; i >= 0; --i ) { 5396 Node* m = n->raw_out(i); // Child 5397 if( m->is_CFG() && !is_visited(m) ) { // Only for CFG children 5398 // Scan over children's children to find loop 5399 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) { 5400 Node* l = m->fast_out(j); 5401 if( is_visited(l) && // Been visited? 5402 !is_postvisited(l) && // But not post-visited 5403 get_preorder(l) < pre_order ) { // And smaller pre-order 5404 // Found! Scan the DFS down this path before doing other paths 5405 bltstack.push(m); 5406 break; 5407 } 5408 } 5409 } 5410 } 5411 pre_order++; 5412 } 5413 else if ( !is_postvisited(n) ) { 5414 // Note: build_loop_tree_impl() adds out edges on rare occasions, 5415 // such as com.sun.rsasign.am::a. 5416 // For non-recursive version, first, process current children. 5417 // On next iteration, check if additional children were added. 5418 for ( int k = n->outcnt() - 1; k >= 0; --k ) { 5419 Node* u = n->raw_out(k); 5420 if ( u->is_CFG() && !is_visited(u) ) { 5421 bltstack.push(u); 5422 } 5423 } 5424 if ( bltstack.length() == stack_size ) { 5425 // There were no additional children, post visit node now 5426 (void)bltstack.pop(); // Remove node from stack 5427 pre_order = build_loop_tree_impl( n, pre_order ); 5428 // Check for bailout 5429 if (C->failing()) { 5430 return; 5431 } 5432 // Check to grow _preorders[] array for the case when 5433 // build_loop_tree_impl() adds new nodes. 5434 check_grow_preorders(); 5435 } 5436 } 5437 else { 5438 (void)bltstack.pop(); // Remove post-visited node from stack 5439 } 5440 } 5441 DEBUG_ONLY(verify_regions_in_irreducible_loops();) 5442 } 5443 5444 //------------------------------build_loop_tree_impl--------------------------- 5445 int PhaseIdealLoop::build_loop_tree_impl( Node *n, int pre_order ) { 5446 // ---- Post-pass Work ---- 5447 // Pre-walked but not post-walked nodes need a pre_order number. 5448 5449 // Tightest enclosing loop for this Node 5450 IdealLoopTree *innermost = nullptr; 5451 5452 // For all children, see if any edge is a backedge. If so, make a loop 5453 // for it. Then find the tightest enclosing loop for the self Node. 5454 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) { 5455 Node* m = n->fast_out(i); // Child 5456 if( n == m ) continue; // Ignore control self-cycles 5457 if( !m->is_CFG() ) continue;// Ignore non-CFG edges 5458 5459 IdealLoopTree *l; // Child's loop 5460 if( !is_postvisited(m) ) { // Child visited but not post-visited? 5461 // Found a backedge 5462 assert( get_preorder(m) < pre_order, "should be backedge" ); 5463 // Check for the RootNode, which is already a LoopNode and is allowed 5464 // to have multiple "backedges". 5465 if( m == C->root()) { // Found the root? 5466 l = _ltree_root; // Root is the outermost LoopNode 5467 } else { // Else found a nested loop 5468 // Insert a LoopNode to mark this loop. 5469 l = new IdealLoopTree(this, m, n); 5470 } // End of Else found a nested loop 5471 if( !has_loop(m) ) // If 'm' does not already have a loop set 5472 set_loop(m, l); // Set loop header to loop now 5473 5474 } else { // Else not a nested loop 5475 if (!_loop_or_ctrl[m->_idx]) continue; // Dead code has no loop 5476 l = get_loop(m); // Get previously determined loop 5477 // If successor is header of a loop (nest), move up-loop till it 5478 // is a member of some outer enclosing loop. Since there are no 5479 // shared headers (I've split them already) I only need to go up 5480 // at most 1 level. 5481 while( l && l->_head == m ) // Successor heads loop? 5482 l = l->_parent; // Move up 1 for me 5483 // If this loop is not properly parented, then this loop 5484 // has no exit path out, i.e. its an infinite loop. 5485 if( !l ) { 5486 // Make loop "reachable" from root so the CFG is reachable. Basically 5487 // insert a bogus loop exit that is never taken. 'm', the loop head, 5488 // points to 'n', one (of possibly many) fall-in paths. There may be 5489 // many backedges as well. 5490 5491 // Here I set the loop to be the root loop. I could have, after 5492 // inserting a bogus loop exit, restarted the recursion and found my 5493 // new loop exit. This would make the infinite loop a first-class 5494 // loop and it would then get properly optimized. What's the use of 5495 // optimizing an infinite loop? 5496 l = _ltree_root; // Oops, found infinite loop 5497 5498 if (!_verify_only) { 5499 // Insert the NeverBranch between 'm' and it's control user. 5500 NeverBranchNode *iff = new NeverBranchNode( m ); 5501 _igvn.register_new_node_with_optimizer(iff); 5502 set_loop(iff, l); 5503 Node *if_t = new CProjNode( iff, 0 ); 5504 _igvn.register_new_node_with_optimizer(if_t); 5505 set_loop(if_t, l); 5506 5507 Node* cfg = nullptr; // Find the One True Control User of m 5508 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) { 5509 Node* x = m->fast_out(j); 5510 if (x->is_CFG() && x != m && x != iff) 5511 { cfg = x; break; } 5512 } 5513 assert(cfg != nullptr, "must find the control user of m"); 5514 uint k = 0; // Probably cfg->in(0) 5515 while( cfg->in(k) != m ) k++; // But check in case cfg is a Region 5516 _igvn.replace_input_of(cfg, k, if_t); // Now point to NeverBranch 5517 5518 // Now create the never-taken loop exit 5519 Node *if_f = new CProjNode( iff, 1 ); 5520 _igvn.register_new_node_with_optimizer(if_f); 5521 set_loop(if_f, l); 5522 // Find frame ptr for Halt. Relies on the optimizer 5523 // V-N'ing. Easier and quicker than searching through 5524 // the program structure. 5525 Node *frame = new ParmNode( C->start(), TypeFunc::FramePtr ); 5526 _igvn.register_new_node_with_optimizer(frame); 5527 // Halt & Catch Fire 5528 Node* halt = new HaltNode(if_f, frame, "never-taken loop exit reached"); 5529 _igvn.register_new_node_with_optimizer(halt); 5530 set_loop(halt, l); 5531 _igvn.add_input_to(C->root(), halt); 5532 } 5533 set_loop(C->root(), _ltree_root); 5534 } 5535 } 5536 if (is_postvisited(l->_head)) { 5537 // We are currently visiting l, but its head has already been post-visited. 5538 // l is irreducible: we just found a second entry m. 5539 _has_irreducible_loops = true; 5540 RegionNode* secondary_entry = m->as_Region(); 5541 DEBUG_ONLY(secondary_entry->verify_can_be_irreducible_entry();) 5542 5543 // Walk up the loop-tree, mark all loops that are already post-visited as irreducible 5544 // Since m is a secondary entry to them all. 5545 while( is_postvisited(l->_head) ) { 5546 l->_irreducible = 1; // = true 5547 RegionNode* head = l->_head->as_Region(); 5548 DEBUG_ONLY(head->verify_can_be_irreducible_entry();) 5549 l = l->_parent; 5550 // Check for bad CFG here to prevent crash, and bailout of compile 5551 if (l == nullptr) { 5552 #ifndef PRODUCT 5553 if (TraceLoopOpts) { 5554 tty->print_cr("bailout: unhandled CFG: infinite irreducible loop"); 5555 m->dump(); 5556 } 5557 #endif 5558 // This is a rare case that we do not want to handle in C2. 5559 C->record_method_not_compilable("unhandled CFG detected during loop optimization"); 5560 return pre_order; 5561 } 5562 } 5563 } 5564 if (!_verify_only) { 5565 C->set_has_irreducible_loop(_has_irreducible_loops); 5566 } 5567 5568 // This Node might be a decision point for loops. It is only if 5569 // it's children belong to several different loops. The sort call 5570 // does a trivial amount of work if there is only 1 child or all 5571 // children belong to the same loop. If however, the children 5572 // belong to different loops, the sort call will properly set the 5573 // _parent pointers to show how the loops nest. 5574 // 5575 // In any case, it returns the tightest enclosing loop. 5576 innermost = sort( l, innermost ); 5577 } 5578 5579 // Def-use info will have some dead stuff; dead stuff will have no 5580 // loop decided on. 5581 5582 // Am I a loop header? If so fix up my parent's child and next ptrs. 5583 if( innermost && innermost->_head == n ) { 5584 assert( get_loop(n) == innermost, "" ); 5585 IdealLoopTree *p = innermost->_parent; 5586 IdealLoopTree *l = innermost; 5587 while( p && l->_head == n ) { 5588 l->_next = p->_child; // Put self on parents 'next child' 5589 p->_child = l; // Make self as first child of parent 5590 l = p; // Now walk up the parent chain 5591 p = l->_parent; 5592 } 5593 } else { 5594 // Note that it is possible for a LoopNode to reach here, if the 5595 // backedge has been made unreachable (hence the LoopNode no longer 5596 // denotes a Loop, and will eventually be removed). 5597 5598 // Record tightest enclosing loop for self. Mark as post-visited. 5599 set_loop(n, innermost); 5600 // Also record has_call flag early on 5601 if( innermost ) { 5602 if( n->is_Call() && !n->is_CallLeaf() && !n->is_macro() ) { 5603 // Do not count uncommon calls 5604 if( !n->is_CallStaticJava() || !n->as_CallStaticJava()->_name ) { 5605 Node *iff = n->in(0)->in(0); 5606 // No any calls for vectorized loops. 5607 if (C->do_superword() || 5608 !iff->is_If() || 5609 (n->in(0)->Opcode() == Op_IfFalse && (1.0 - iff->as_If()->_prob) >= 0.01) || 5610 iff->as_If()->_prob >= 0.01) { 5611 innermost->_has_call = 1; 5612 } 5613 } 5614 } else if( n->is_Allocate() && n->as_Allocate()->_is_scalar_replaceable ) { 5615 // Disable loop optimizations if the loop has a scalar replaceable 5616 // allocation. This disabling may cause a potential performance lost 5617 // if the allocation is not eliminated for some reason. 5618 innermost->_allow_optimizations = false; 5619 innermost->_has_call = 1; // = true 5620 } else if (n->Opcode() == Op_SafePoint) { 5621 // Record all safepoints in this loop. 5622 if (innermost->_safepts == nullptr) innermost->_safepts = new Node_List(); 5623 innermost->_safepts->push(n); 5624 } 5625 } 5626 } 5627 5628 // Flag as post-visited now 5629 set_postvisited(n); 5630 return pre_order; 5631 } 5632 5633 #ifdef ASSERT 5634 //--------------------------verify_regions_in_irreducible_loops---------------- 5635 // Iterate down from Root through CFG, verify for every region: 5636 // if it is in an irreducible loop it must be marked as such 5637 void PhaseIdealLoop::verify_regions_in_irreducible_loops() { 5638 ResourceMark rm; 5639 if (!_has_irreducible_loops) { 5640 // last build_loop_tree has not found any irreducible loops 5641 // hence no region has to be marked is_in_irreduible_loop 5642 return; 5643 } 5644 5645 RootNode* root = C->root(); 5646 Unique_Node_List worklist; // visit all nodes once 5647 worklist.push(root); 5648 bool failure = false; 5649 for (uint i = 0; i < worklist.size(); i++) { 5650 Node* n = worklist.at(i); 5651 if (n->is_Region()) { 5652 RegionNode* region = n->as_Region(); 5653 if (is_in_irreducible_loop(region) && 5654 region->loop_status() == RegionNode::LoopStatus::Reducible) { 5655 failure = true; 5656 tty->print("irreducible! "); 5657 region->dump(); 5658 } 5659 } 5660 for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) { 5661 Node* use = n->fast_out(j); 5662 if (use->is_CFG()) { 5663 worklist.push(use); // push if was not pushed before 5664 } 5665 } 5666 } 5667 assert(!failure, "region in irreducible loop was marked as reducible"); 5668 } 5669 5670 //---------------------------is_in_irreducible_loop------------------------- 5671 // Analogous to ciTypeFlow::Block::is_in_irreducible_loop 5672 bool PhaseIdealLoop::is_in_irreducible_loop(RegionNode* region) { 5673 if (!_has_irreducible_loops) { 5674 return false; // no irreducible loop in graph 5675 } 5676 IdealLoopTree* l = get_loop(region); // l: innermost loop that contains region 5677 do { 5678 if (l->_irreducible) { 5679 return true; // found it 5680 } 5681 if (l == _ltree_root) { 5682 return false; // reached root, terimnate 5683 } 5684 l = l->_parent; 5685 } while (l != nullptr); 5686 assert(region->is_in_infinite_subgraph(), "must be in infinite subgraph"); 5687 // We have "l->_parent == nullptr", which happens only for infinite loops, 5688 // where no parent is attached to the loop. We did not find any irreducible 5689 // loop from this block out to lp. Thus lp only has one entry, and no exit 5690 // (it is infinite and reducible). We can always rewrite an infinite loop 5691 // that is nested inside other loops: 5692 // while(condition) { infinite_loop; } 5693 // with an equivalent program where the infinite loop is an outermost loop 5694 // that is not nested in any loop: 5695 // while(condition) { break; } infinite_loop; 5696 // Thus, we can understand lp as an outermost loop, and can terminate and 5697 // conclude: this block is in no irreducible loop. 5698 return false; 5699 } 5700 #endif 5701 5702 //------------------------------build_loop_early------------------------------- 5703 // Put Data nodes into some loop nest, by setting the _loop_or_ctrl[]->loop mapping. 5704 // First pass computes the earliest controlling node possible. This is the 5705 // controlling input with the deepest dominating depth. 5706 void PhaseIdealLoop::build_loop_early( VectorSet &visited, Node_List &worklist, Node_Stack &nstack ) { 5707 while (worklist.size() != 0) { 5708 // Use local variables nstack_top_n & nstack_top_i to cache values 5709 // on nstack's top. 5710 Node *nstack_top_n = worklist.pop(); 5711 uint nstack_top_i = 0; 5712 //while_nstack_nonempty: 5713 while (true) { 5714 // Get parent node and next input's index from stack's top. 5715 Node *n = nstack_top_n; 5716 uint i = nstack_top_i; 5717 uint cnt = n->req(); // Count of inputs 5718 if (i == 0) { // Pre-process the node. 5719 if( has_node(n) && // Have either loop or control already? 5720 !has_ctrl(n) ) { // Have loop picked out already? 5721 // During "merge_many_backedges" we fold up several nested loops 5722 // into a single loop. This makes the members of the original 5723 // loop bodies pointing to dead loops; they need to move up 5724 // to the new UNION'd larger loop. I set the _head field of these 5725 // dead loops to null and the _parent field points to the owning 5726 // loop. Shades of UNION-FIND algorithm. 5727 IdealLoopTree *ilt; 5728 while( !(ilt = get_loop(n))->_head ) { 5729 // Normally I would use a set_loop here. But in this one special 5730 // case, it is legal (and expected) to change what loop a Node 5731 // belongs to. 5732 _loop_or_ctrl.map(n->_idx, (Node*)(ilt->_parent)); 5733 } 5734 // Remove safepoints ONLY if I've already seen I don't need one. 5735 // (the old code here would yank a 2nd safepoint after seeing a 5736 // first one, even though the 1st did not dominate in the loop body 5737 // and thus could be avoided indefinitely) 5738 if( !_verify_only && !_verify_me && ilt->_has_sfpt && n->Opcode() == Op_SafePoint && 5739 is_deleteable_safept(n)) { 5740 Node *in = n->in(TypeFunc::Control); 5741 lazy_replace(n,in); // Pull safepoint now 5742 if (ilt->_safepts != nullptr) { 5743 ilt->_safepts->yank(n); 5744 } 5745 // Carry on with the recursion "as if" we are walking 5746 // only the control input 5747 if( !visited.test_set( in->_idx ) ) { 5748 worklist.push(in); // Visit this guy later, using worklist 5749 } 5750 // Get next node from nstack: 5751 // - skip n's inputs processing by setting i > cnt; 5752 // - we also will not call set_early_ctrl(n) since 5753 // has_node(n) == true (see the condition above). 5754 i = cnt + 1; 5755 } 5756 } 5757 } // if (i == 0) 5758 5759 // Visit all inputs 5760 bool done = true; // Assume all n's inputs will be processed 5761 while (i < cnt) { 5762 Node *in = n->in(i); 5763 ++i; 5764 if (in == nullptr) continue; 5765 if (in->pinned() && !in->is_CFG()) 5766 set_ctrl(in, in->in(0)); 5767 int is_visited = visited.test_set( in->_idx ); 5768 if (!has_node(in)) { // No controlling input yet? 5769 assert( !in->is_CFG(), "CFG Node with no controlling input?" ); 5770 assert( !is_visited, "visit only once" ); 5771 nstack.push(n, i); // Save parent node and next input's index. 5772 nstack_top_n = in; // Process current input now. 5773 nstack_top_i = 0; 5774 done = false; // Not all n's inputs processed. 5775 break; // continue while_nstack_nonempty; 5776 } else if (!is_visited) { 5777 // This guy has a location picked out for him, but has not yet 5778 // been visited. Happens to all CFG nodes, for instance. 5779 // Visit him using the worklist instead of recursion, to break 5780 // cycles. Since he has a location already we do not need to 5781 // find his location before proceeding with the current Node. 5782 worklist.push(in); // Visit this guy later, using worklist 5783 } 5784 } 5785 if (done) { 5786 // All of n's inputs have been processed, complete post-processing. 5787 5788 // Compute earliest point this Node can go. 5789 // CFG, Phi, pinned nodes already know their controlling input. 5790 if (!has_node(n)) { 5791 // Record earliest legal location 5792 set_early_ctrl(n, false); 5793 } 5794 if (nstack.is_empty()) { 5795 // Finished all nodes on stack. 5796 // Process next node on the worklist. 5797 break; 5798 } 5799 // Get saved parent node and next input's index. 5800 nstack_top_n = nstack.node(); 5801 nstack_top_i = nstack.index(); 5802 nstack.pop(); 5803 } 5804 } // while (true) 5805 } 5806 } 5807 5808 //------------------------------dom_lca_internal-------------------------------- 5809 // Pair-wise LCA 5810 Node *PhaseIdealLoop::dom_lca_internal( Node *n1, Node *n2 ) const { 5811 if( !n1 ) return n2; // Handle null original LCA 5812 assert( n1->is_CFG(), "" ); 5813 assert( n2->is_CFG(), "" ); 5814 // find LCA of all uses 5815 uint d1 = dom_depth(n1); 5816 uint d2 = dom_depth(n2); 5817 while (n1 != n2) { 5818 if (d1 > d2) { 5819 n1 = idom(n1); 5820 d1 = dom_depth(n1); 5821 } else if (d1 < d2) { 5822 n2 = idom(n2); 5823 d2 = dom_depth(n2); 5824 } else { 5825 // Here d1 == d2. Due to edits of the dominator-tree, sections 5826 // of the tree might have the same depth. These sections have 5827 // to be searched more carefully. 5828 5829 // Scan up all the n1's with equal depth, looking for n2. 5830 Node *t1 = idom(n1); 5831 while (dom_depth(t1) == d1) { 5832 if (t1 == n2) return n2; 5833 t1 = idom(t1); 5834 } 5835 // Scan up all the n2's with equal depth, looking for n1. 5836 Node *t2 = idom(n2); 5837 while (dom_depth(t2) == d2) { 5838 if (t2 == n1) return n1; 5839 t2 = idom(t2); 5840 } 5841 // Move up to a new dominator-depth value as well as up the dom-tree. 5842 n1 = t1; 5843 n2 = t2; 5844 d1 = dom_depth(n1); 5845 d2 = dom_depth(n2); 5846 } 5847 } 5848 return n1; 5849 } 5850 5851 //------------------------------compute_idom----------------------------------- 5852 // Locally compute IDOM using dom_lca call. Correct only if the incoming 5853 // IDOMs are correct. 5854 Node *PhaseIdealLoop::compute_idom( Node *region ) const { 5855 assert( region->is_Region(), "" ); 5856 Node *LCA = nullptr; 5857 for( uint i = 1; i < region->req(); i++ ) { 5858 if( region->in(i) != C->top() ) 5859 LCA = dom_lca( LCA, region->in(i) ); 5860 } 5861 return LCA; 5862 } 5863 5864 bool PhaseIdealLoop::verify_dominance(Node* n, Node* use, Node* LCA, Node* early) { 5865 bool had_error = false; 5866 #ifdef ASSERT 5867 if (early != C->root()) { 5868 // Make sure that there's a dominance path from LCA to early 5869 Node* d = LCA; 5870 while (d != early) { 5871 if (d == C->root()) { 5872 dump_bad_graph("Bad graph detected in compute_lca_of_uses", n, early, LCA); 5873 tty->print_cr("*** Use %d isn't dominated by def %d ***", use->_idx, n->_idx); 5874 had_error = true; 5875 break; 5876 } 5877 d = idom(d); 5878 } 5879 } 5880 #endif 5881 return had_error; 5882 } 5883 5884 5885 Node* PhaseIdealLoop::compute_lca_of_uses(Node* n, Node* early, bool verify) { 5886 // Compute LCA over list of uses 5887 bool had_error = false; 5888 Node *LCA = nullptr; 5889 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax && LCA != early; i++) { 5890 Node* c = n->fast_out(i); 5891 if (_loop_or_ctrl[c->_idx] == nullptr) 5892 continue; // Skip the occasional dead node 5893 if( c->is_Phi() ) { // For Phis, we must land above on the path 5894 for( uint j=1; j<c->req(); j++ ) {// For all inputs 5895 if( c->in(j) == n ) { // Found matching input? 5896 Node *use = c->in(0)->in(j); 5897 if (_verify_only && use->is_top()) continue; 5898 LCA = dom_lca_for_get_late_ctrl( LCA, use, n ); 5899 if (verify) had_error = verify_dominance(n, use, LCA, early) || had_error; 5900 } 5901 } 5902 } else { 5903 // For CFG data-users, use is in the block just prior 5904 Node *use = has_ctrl(c) ? get_ctrl(c) : c->in(0); 5905 LCA = dom_lca_for_get_late_ctrl( LCA, use, n ); 5906 if (verify) had_error = verify_dominance(n, use, LCA, early) || had_error; 5907 } 5908 } 5909 assert(!had_error, "bad dominance"); 5910 return LCA; 5911 } 5912 5913 // Check the shape of the graph at the loop entry. In some cases, 5914 // the shape of the graph does not match the shape outlined below. 5915 // That is caused by the Opaque1 node "protecting" the shape of 5916 // the graph being removed by, for example, the IGVN performed 5917 // in PhaseIdealLoop::build_and_optimize(). 5918 // 5919 // After the Opaque1 node has been removed, optimizations (e.g., split-if, 5920 // loop unswitching, and IGVN, or a combination of them) can freely change 5921 // the graph's shape. As a result, the graph shape outlined below cannot 5922 // be guaranteed anymore. 5923 Node* CountedLoopNode::is_canonical_loop_entry() { 5924 if (!is_main_loop() && !is_post_loop()) { 5925 return nullptr; 5926 } 5927 Node* ctrl = skip_assertion_predicates_with_halt(); 5928 5929 if (ctrl == nullptr || (!ctrl->is_IfTrue() && !ctrl->is_IfFalse())) { 5930 return nullptr; 5931 } 5932 Node* iffm = ctrl->in(0); 5933 if (iffm == nullptr || iffm->Opcode() != Op_If) { 5934 return nullptr; 5935 } 5936 Node* bolzm = iffm->in(1); 5937 if (bolzm == nullptr || !bolzm->is_Bool()) { 5938 return nullptr; 5939 } 5940 Node* cmpzm = bolzm->in(1); 5941 if (cmpzm == nullptr || !cmpzm->is_Cmp()) { 5942 return nullptr; 5943 } 5944 5945 uint input = is_main_loop() ? 2 : 1; 5946 if (input >= cmpzm->req() || cmpzm->in(input) == nullptr) { 5947 return nullptr; 5948 } 5949 bool res = cmpzm->in(input)->Opcode() == Op_OpaqueZeroTripGuard; 5950 #ifdef ASSERT 5951 bool found_opaque = false; 5952 for (uint i = 1; i < cmpzm->req(); i++) { 5953 Node* opnd = cmpzm->in(i); 5954 if (opnd && opnd->is_Opaque1()) { 5955 found_opaque = true; 5956 break; 5957 } 5958 } 5959 assert(found_opaque == res, "wrong pattern"); 5960 #endif 5961 return res ? cmpzm->in(input) : nullptr; 5962 } 5963 5964 // Find pre loop end from main loop. Returns nullptr if none. 5965 CountedLoopEndNode* CountedLoopNode::find_pre_loop_end() { 5966 assert(is_main_loop(), "Can only find pre-loop from main-loop"); 5967 // The loop cannot be optimized if the graph shape at the loop entry is 5968 // inappropriate. 5969 if (is_canonical_loop_entry() == nullptr) { 5970 return nullptr; 5971 } 5972 5973 Node* p_f = skip_assertion_predicates_with_halt()->in(0)->in(0); 5974 if (!p_f->is_IfFalse() || !p_f->in(0)->is_CountedLoopEnd()) { 5975 return nullptr; 5976 } 5977 CountedLoopEndNode* pre_end = p_f->in(0)->as_CountedLoopEnd(); 5978 CountedLoopNode* loop_node = pre_end->loopnode(); 5979 if (loop_node == nullptr || !loop_node->is_pre_loop()) { 5980 return nullptr; 5981 } 5982 return pre_end; 5983 } 5984 5985 //------------------------------get_late_ctrl---------------------------------- 5986 // Compute latest legal control. 5987 Node *PhaseIdealLoop::get_late_ctrl( Node *n, Node *early ) { 5988 assert(early != nullptr, "early control should not be null"); 5989 5990 Node* LCA = compute_lca_of_uses(n, early); 5991 #ifdef ASSERT 5992 if (LCA == C->root() && LCA != early) { 5993 // def doesn't dominate uses so print some useful debugging output 5994 compute_lca_of_uses(n, early, true); 5995 } 5996 #endif 5997 5998 if (n->is_Load() && LCA != early) { 5999 LCA = get_late_ctrl_with_anti_dep(n->as_Load(), early, LCA); 6000 } 6001 6002 assert(LCA == find_non_split_ctrl(LCA), "unexpected late control"); 6003 return LCA; 6004 } 6005 6006 // if this is a load, check for anti-dependent stores 6007 // We use a conservative algorithm to identify potential interfering 6008 // instructions and for rescheduling the load. The users of the memory 6009 // input of this load are examined. Any use which is not a load and is 6010 // dominated by early is considered a potentially interfering store. 6011 // This can produce false positives. 6012 Node* PhaseIdealLoop::get_late_ctrl_with_anti_dep(LoadNode* n, Node* early, Node* LCA) { 6013 int load_alias_idx = C->get_alias_index(n->adr_type()); 6014 if (C->alias_type(load_alias_idx)->is_rewritable()) { 6015 Unique_Node_List worklist; 6016 6017 Node* mem = n->in(MemNode::Memory); 6018 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) { 6019 Node* s = mem->fast_out(i); 6020 worklist.push(s); 6021 } 6022 for (uint i = 0; i < worklist.size() && LCA != early; i++) { 6023 Node* s = worklist.at(i); 6024 if (s->is_Load() || s->Opcode() == Op_SafePoint || 6025 (s->is_CallStaticJava() && s->as_CallStaticJava()->uncommon_trap_request() != 0) || 6026 s->is_Phi()) { 6027 continue; 6028 } else if (s->is_MergeMem()) { 6029 for (DUIterator_Fast imax, i = s->fast_outs(imax); i < imax; i++) { 6030 Node* s1 = s->fast_out(i); 6031 worklist.push(s1); 6032 } 6033 } else { 6034 Node* sctrl = has_ctrl(s) ? get_ctrl(s) : s->in(0); 6035 assert(sctrl != nullptr || !s->is_reachable_from_root(), "must have control"); 6036 if (sctrl != nullptr && !sctrl->is_top() && is_dominator(early, sctrl)) { 6037 const TypePtr* adr_type = s->adr_type(); 6038 if (s->is_ArrayCopy()) { 6039 // Copy to known instance needs destination type to test for aliasing 6040 const TypePtr* dest_type = s->as_ArrayCopy()->_dest_type; 6041 if (dest_type != TypeOopPtr::BOTTOM) { 6042 adr_type = dest_type; 6043 } 6044 } 6045 if (C->can_alias(adr_type, load_alias_idx)) { 6046 LCA = dom_lca_for_get_late_ctrl(LCA, sctrl, n); 6047 } else if (s->is_CFG() && s->is_Multi()) { 6048 // Look for the memory use of s (that is the use of its memory projection) 6049 for (DUIterator_Fast imax, i = s->fast_outs(imax); i < imax; i++) { 6050 Node* s1 = s->fast_out(i); 6051 assert(s1->is_Proj(), "projection expected"); 6052 if (_igvn.type(s1) == Type::MEMORY) { 6053 for (DUIterator_Fast jmax, j = s1->fast_outs(jmax); j < jmax; j++) { 6054 Node* s2 = s1->fast_out(j); 6055 worklist.push(s2); 6056 } 6057 } 6058 } 6059 } 6060 } 6061 } 6062 } 6063 // For Phis only consider Region's inputs that were reached by following the memory edges 6064 if (LCA != early) { 6065 for (uint i = 0; i < worklist.size(); i++) { 6066 Node* s = worklist.at(i); 6067 if (s->is_Phi() && C->can_alias(s->adr_type(), load_alias_idx)) { 6068 Node* r = s->in(0); 6069 for (uint j = 1; j < s->req(); j++) { 6070 Node* in = s->in(j); 6071 Node* r_in = r->in(j); 6072 // We can't reach any node from a Phi because we don't enqueue Phi's uses above 6073 if (((worklist.member(in) && !in->is_Phi()) || in == mem) && is_dominator(early, r_in)) { 6074 LCA = dom_lca_for_get_late_ctrl(LCA, r_in, n); 6075 } 6076 } 6077 } 6078 } 6079 } 6080 } 6081 return LCA; 6082 } 6083 6084 // true if CFG node d dominates CFG node n 6085 bool PhaseIdealLoop::is_dominator(Node *d, Node *n) { 6086 if (d == n) 6087 return true; 6088 assert(d->is_CFG() && n->is_CFG(), "must have CFG nodes"); 6089 uint dd = dom_depth(d); 6090 while (dom_depth(n) >= dd) { 6091 if (n == d) 6092 return true; 6093 n = idom(n); 6094 } 6095 return false; 6096 } 6097 6098 //------------------------------dom_lca_for_get_late_ctrl_internal------------- 6099 // Pair-wise LCA with tags. 6100 // Tag each index with the node 'tag' currently being processed 6101 // before advancing up the dominator chain using idom(). 6102 // Later calls that find a match to 'tag' know that this path has already 6103 // been considered in the current LCA (which is input 'n1' by convention). 6104 // Since get_late_ctrl() is only called once for each node, the tag array 6105 // does not need to be cleared between calls to get_late_ctrl(). 6106 // Algorithm trades a larger constant factor for better asymptotic behavior 6107 // 6108 Node *PhaseIdealLoop::dom_lca_for_get_late_ctrl_internal(Node *n1, Node *n2, Node *tag_node) { 6109 uint d1 = dom_depth(n1); 6110 uint d2 = dom_depth(n2); 6111 jlong tag = tag_node->_idx | (((jlong)_dom_lca_tags_round) << 32); 6112 6113 do { 6114 if (d1 > d2) { 6115 // current lca is deeper than n2 6116 _dom_lca_tags.at_put_grow(n1->_idx, tag); 6117 n1 = idom(n1); 6118 d1 = dom_depth(n1); 6119 } else if (d1 < d2) { 6120 // n2 is deeper than current lca 6121 jlong memo = _dom_lca_tags.at_grow(n2->_idx, 0); 6122 if (memo == tag) { 6123 return n1; // Return the current LCA 6124 } 6125 _dom_lca_tags.at_put_grow(n2->_idx, tag); 6126 n2 = idom(n2); 6127 d2 = dom_depth(n2); 6128 } else { 6129 // Here d1 == d2. Due to edits of the dominator-tree, sections 6130 // of the tree might have the same depth. These sections have 6131 // to be searched more carefully. 6132 6133 // Scan up all the n1's with equal depth, looking for n2. 6134 _dom_lca_tags.at_put_grow(n1->_idx, tag); 6135 Node *t1 = idom(n1); 6136 while (dom_depth(t1) == d1) { 6137 if (t1 == n2) return n2; 6138 _dom_lca_tags.at_put_grow(t1->_idx, tag); 6139 t1 = idom(t1); 6140 } 6141 // Scan up all the n2's with equal depth, looking for n1. 6142 _dom_lca_tags.at_put_grow(n2->_idx, tag); 6143 Node *t2 = idom(n2); 6144 while (dom_depth(t2) == d2) { 6145 if (t2 == n1) return n1; 6146 _dom_lca_tags.at_put_grow(t2->_idx, tag); 6147 t2 = idom(t2); 6148 } 6149 // Move up to a new dominator-depth value as well as up the dom-tree. 6150 n1 = t1; 6151 n2 = t2; 6152 d1 = dom_depth(n1); 6153 d2 = dom_depth(n2); 6154 } 6155 } while (n1 != n2); 6156 return n1; 6157 } 6158 6159 //------------------------------init_dom_lca_tags------------------------------ 6160 // Tag could be a node's integer index, 32bits instead of 64bits in some cases 6161 // Intended use does not involve any growth for the array, so it could 6162 // be of fixed size. 6163 void PhaseIdealLoop::init_dom_lca_tags() { 6164 uint limit = C->unique() + 1; 6165 _dom_lca_tags.at_grow(limit, 0); 6166 _dom_lca_tags_round = 0; 6167 #ifdef ASSERT 6168 for (uint i = 0; i < limit; ++i) { 6169 assert(_dom_lca_tags.at(i) == 0, "Must be distinct from each node pointer"); 6170 } 6171 #endif // ASSERT 6172 } 6173 6174 //------------------------------build_loop_late-------------------------------- 6175 // Put Data nodes into some loop nest, by setting the _loop_or_ctrl[]->loop mapping. 6176 // Second pass finds latest legal placement, and ideal loop placement. 6177 void PhaseIdealLoop::build_loop_late( VectorSet &visited, Node_List &worklist, Node_Stack &nstack ) { 6178 while (worklist.size() != 0) { 6179 Node *n = worklist.pop(); 6180 // Only visit once 6181 if (visited.test_set(n->_idx)) continue; 6182 uint cnt = n->outcnt(); 6183 uint i = 0; 6184 while (true) { 6185 assert(_loop_or_ctrl[n->_idx], "no dead nodes"); 6186 // Visit all children 6187 if (i < cnt) { 6188 Node* use = n->raw_out(i); 6189 ++i; 6190 // Check for dead uses. Aggressively prune such junk. It might be 6191 // dead in the global sense, but still have local uses so I cannot 6192 // easily call 'remove_dead_node'. 6193 if (_loop_or_ctrl[use->_idx] != nullptr || use->is_top()) { // Not dead? 6194 // Due to cycles, we might not hit the same fixed point in the verify 6195 // pass as we do in the regular pass. Instead, visit such phis as 6196 // simple uses of the loop head. 6197 if( use->in(0) && (use->is_CFG() || use->is_Phi()) ) { 6198 if( !visited.test(use->_idx) ) 6199 worklist.push(use); 6200 } else if( !visited.test_set(use->_idx) ) { 6201 nstack.push(n, i); // Save parent and next use's index. 6202 n = use; // Process all children of current use. 6203 cnt = use->outcnt(); 6204 i = 0; 6205 } 6206 } else { 6207 // Do not visit around the backedge of loops via data edges. 6208 // push dead code onto a worklist 6209 _deadlist.push(use); 6210 } 6211 } else { 6212 // All of n's children have been processed, complete post-processing. 6213 build_loop_late_post(n); 6214 if (C->failing()) { return; } 6215 if (nstack.is_empty()) { 6216 // Finished all nodes on stack. 6217 // Process next node on the worklist. 6218 break; 6219 } 6220 // Get saved parent node and next use's index. Visit the rest of uses. 6221 n = nstack.node(); 6222 cnt = n->outcnt(); 6223 i = nstack.index(); 6224 nstack.pop(); 6225 } 6226 } 6227 } 6228 } 6229 6230 // Verify that no data node is scheduled in the outer loop of a strip 6231 // mined loop. 6232 void PhaseIdealLoop::verify_strip_mined_scheduling(Node *n, Node* least) { 6233 #ifdef ASSERT 6234 if (get_loop(least)->_nest == 0) { 6235 return; 6236 } 6237 IdealLoopTree* loop = get_loop(least); 6238 Node* head = loop->_head; 6239 if (head->is_OuterStripMinedLoop() && 6240 // Verification can't be applied to fully built strip mined loops 6241 head->as_Loop()->outer_loop_end()->in(1)->find_int_con(-1) == 0) { 6242 Node* sfpt = head->as_Loop()->outer_safepoint(); 6243 ResourceMark rm; 6244 Unique_Node_List wq; 6245 wq.push(sfpt); 6246 for (uint i = 0; i < wq.size(); i++) { 6247 Node *m = wq.at(i); 6248 for (uint i = 1; i < m->req(); i++) { 6249 Node* nn = m->in(i); 6250 if (nn == n) { 6251 return; 6252 } 6253 if (nn != nullptr && has_ctrl(nn) && get_loop(get_ctrl(nn)) == loop) { 6254 wq.push(nn); 6255 } 6256 } 6257 } 6258 ShouldNotReachHere(); 6259 } 6260 #endif 6261 } 6262 6263 6264 //------------------------------build_loop_late_post--------------------------- 6265 // Put Data nodes into some loop nest, by setting the _loop_or_ctrl[]->loop mapping. 6266 // Second pass finds latest legal placement, and ideal loop placement. 6267 void PhaseIdealLoop::build_loop_late_post(Node *n) { 6268 build_loop_late_post_work(n, true); 6269 } 6270 6271 void PhaseIdealLoop::build_loop_late_post_work(Node *n, bool pinned) { 6272 6273 if (n->req() == 2 && (n->Opcode() == Op_ConvI2L || n->Opcode() == Op_CastII) && !C->major_progress() && !_verify_only) { 6274 _igvn._worklist.push(n); // Maybe we'll normalize it, if no more loops. 6275 } 6276 6277 #ifdef ASSERT 6278 if (_verify_only && !n->is_CFG()) { 6279 // Check def-use domination. 6280 compute_lca_of_uses(n, get_ctrl(n), true /* verify */); 6281 } 6282 #endif 6283 6284 // CFG and pinned nodes already handled 6285 if( n->in(0) ) { 6286 if( n->in(0)->is_top() ) return; // Dead? 6287 6288 // We'd like +VerifyLoopOptimizations to not believe that Mod's/Loads 6289 // _must_ be pinned (they have to observe their control edge of course). 6290 // Unlike Stores (which modify an unallocable resource, the memory 6291 // state), Mods/Loads can float around. So free them up. 6292 switch( n->Opcode() ) { 6293 case Op_DivI: 6294 case Op_DivF: 6295 case Op_DivD: 6296 case Op_ModI: 6297 case Op_ModF: 6298 case Op_ModD: 6299 case Op_LoadB: // Same with Loads; they can sink 6300 case Op_LoadUB: // during loop optimizations. 6301 case Op_LoadUS: 6302 case Op_LoadD: 6303 case Op_LoadF: 6304 case Op_LoadI: 6305 case Op_LoadKlass: 6306 case Op_LoadNKlass: 6307 case Op_LoadL: 6308 case Op_LoadS: 6309 case Op_LoadP: 6310 case Op_LoadN: 6311 case Op_LoadRange: 6312 case Op_LoadD_unaligned: 6313 case Op_LoadL_unaligned: 6314 case Op_StrComp: // Does a bunch of load-like effects 6315 case Op_StrEquals: 6316 case Op_StrIndexOf: 6317 case Op_StrIndexOfChar: 6318 case Op_AryEq: 6319 case Op_VectorizedHashCode: 6320 case Op_CountPositives: 6321 pinned = false; 6322 } 6323 if (n->is_CMove() || n->is_ConstraintCast()) { 6324 pinned = false; 6325 } 6326 if( pinned ) { 6327 IdealLoopTree *chosen_loop = get_loop(n->is_CFG() ? n : get_ctrl(n)); 6328 if( !chosen_loop->_child ) // Inner loop? 6329 chosen_loop->_body.push(n); // Collect inner loops 6330 return; 6331 } 6332 } else { // No slot zero 6333 if( n->is_CFG() ) { // CFG with no slot 0 is dead 6334 _loop_or_ctrl.map(n->_idx,0); // No block setting, it's globally dead 6335 return; 6336 } 6337 assert(!n->is_CFG() || n->outcnt() == 0, ""); 6338 } 6339 6340 // Do I have a "safe range" I can select over? 6341 Node *early = get_ctrl(n);// Early location already computed 6342 6343 // Compute latest point this Node can go 6344 Node *LCA = get_late_ctrl( n, early ); 6345 // LCA is null due to uses being dead 6346 if( LCA == nullptr ) { 6347 #ifdef ASSERT 6348 for (DUIterator i1 = n->outs(); n->has_out(i1); i1++) { 6349 assert(_loop_or_ctrl[n->out(i1)->_idx] == nullptr, "all uses must also be dead"); 6350 } 6351 #endif 6352 _loop_or_ctrl.map(n->_idx, 0); // This node is useless 6353 _deadlist.push(n); 6354 return; 6355 } 6356 assert(LCA != nullptr && !LCA->is_top(), "no dead nodes"); 6357 6358 Node *legal = LCA; // Walk 'legal' up the IDOM chain 6359 Node *least = legal; // Best legal position so far 6360 while( early != legal ) { // While not at earliest legal 6361 if (legal->is_Start() && !early->is_Root()) { 6362 #ifdef ASSERT 6363 // Bad graph. Print idom path and fail. 6364 dump_bad_graph("Bad graph detected in build_loop_late", n, early, LCA); 6365 assert(false, "Bad graph detected in build_loop_late"); 6366 #endif 6367 C->record_method_not_compilable("Bad graph detected in build_loop_late"); 6368 return; 6369 } 6370 // Find least loop nesting depth 6371 legal = idom(legal); // Bump up the IDOM tree 6372 // Check for lower nesting depth 6373 if( get_loop(legal)->_nest < get_loop(least)->_nest ) 6374 least = legal; 6375 } 6376 assert(early == legal || legal != C->root(), "bad dominance of inputs"); 6377 6378 if (least != early) { 6379 // Move the node above predicates as far up as possible so a 6380 // following pass of loop predication doesn't hoist a predicate 6381 // that depends on it above that node. 6382 Node* new_ctrl = least; 6383 for (;;) { 6384 if (!new_ctrl->is_Proj()) { 6385 break; 6386 } 6387 CallStaticJavaNode* call = new_ctrl->as_Proj()->is_uncommon_trap_if_pattern(); 6388 if (call == nullptr) { 6389 break; 6390 } 6391 int req = call->uncommon_trap_request(); 6392 Deoptimization::DeoptReason trap_reason = Deoptimization::trap_request_reason(req); 6393 if (trap_reason != Deoptimization::Reason_loop_limit_check && 6394 trap_reason != Deoptimization::Reason_predicate && 6395 trap_reason != Deoptimization::Reason_profile_predicate) { 6396 break; 6397 } 6398 Node* c = new_ctrl->in(0)->in(0); 6399 if (is_dominator(c, early) && c != early) { 6400 break; 6401 } 6402 new_ctrl = c; 6403 } 6404 least = new_ctrl; 6405 } 6406 // Try not to place code on a loop entry projection 6407 // which can inhibit range check elimination. 6408 if (least != early && !BarrierSet::barrier_set()->barrier_set_c2()->is_gc_specific_loop_opts_pass(_mode)) { 6409 Node* ctrl_out = least->unique_ctrl_out_or_null(); 6410 if (ctrl_out != nullptr && ctrl_out->is_Loop() && 6411 least == ctrl_out->in(LoopNode::EntryControl) && 6412 (ctrl_out->is_CountedLoop() || ctrl_out->is_OuterStripMinedLoop())) { 6413 Node* least_dom = idom(least); 6414 if (get_loop(least_dom)->is_member(get_loop(least))) { 6415 least = least_dom; 6416 } 6417 } 6418 } 6419 // Don't extend live ranges of raw oops 6420 if (least != early && n->is_ConstraintCast() && n->in(1)->bottom_type()->isa_rawptr() && 6421 !n->bottom_type()->isa_rawptr()) { 6422 least = early; 6423 } 6424 6425 #ifdef ASSERT 6426 // Broken part of VerifyLoopOptimizations (F) 6427 // Reason: 6428 // _verify_me->get_ctrl_no_update(n) seems to return wrong result 6429 /* 6430 // If verifying, verify that 'verify_me' has a legal location 6431 // and choose it as our location. 6432 if( _verify_me ) { 6433 Node *v_ctrl = _verify_me->get_ctrl_no_update(n); 6434 Node *legal = LCA; 6435 while( early != legal ) { // While not at earliest legal 6436 if( legal == v_ctrl ) break; // Check for prior good location 6437 legal = idom(legal) ;// Bump up the IDOM tree 6438 } 6439 // Check for prior good location 6440 if( legal == v_ctrl ) least = legal; // Keep prior if found 6441 } 6442 */ 6443 #endif 6444 6445 // Assign discovered "here or above" point 6446 least = find_non_split_ctrl(least); 6447 verify_strip_mined_scheduling(n, least); 6448 set_ctrl(n, least); 6449 6450 // Collect inner loop bodies 6451 IdealLoopTree *chosen_loop = get_loop(least); 6452 if( !chosen_loop->_child ) // Inner loop? 6453 chosen_loop->_body.push(n);// Collect inner loops 6454 6455 if (!_verify_only && n->Opcode() == Op_OpaqueZeroTripGuard) { 6456 _zero_trip_guard_opaque_nodes.push(n); 6457 } 6458 6459 } 6460 6461 #ifdef ASSERT 6462 void PhaseIdealLoop::dump_bad_graph(const char* msg, Node* n, Node* early, Node* LCA) { 6463 tty->print_cr("%s", msg); 6464 tty->print("n: "); n->dump(); 6465 tty->print("early(n): "); early->dump(); 6466 if (n->in(0) != nullptr && !n->in(0)->is_top() && 6467 n->in(0) != early && !n->in(0)->is_Root()) { 6468 tty->print("n->in(0): "); n->in(0)->dump(); 6469 } 6470 for (uint i = 1; i < n->req(); i++) { 6471 Node* in1 = n->in(i); 6472 if (in1 != nullptr && in1 != n && !in1->is_top()) { 6473 tty->print("n->in(%d): ", i); in1->dump(); 6474 Node* in1_early = get_ctrl(in1); 6475 tty->print("early(n->in(%d)): ", i); in1_early->dump(); 6476 if (in1->in(0) != nullptr && !in1->in(0)->is_top() && 6477 in1->in(0) != in1_early && !in1->in(0)->is_Root()) { 6478 tty->print("n->in(%d)->in(0): ", i); in1->in(0)->dump(); 6479 } 6480 for (uint j = 1; j < in1->req(); j++) { 6481 Node* in2 = in1->in(j); 6482 if (in2 != nullptr && in2 != n && in2 != in1 && !in2->is_top()) { 6483 tty->print("n->in(%d)->in(%d): ", i, j); in2->dump(); 6484 Node* in2_early = get_ctrl(in2); 6485 tty->print("early(n->in(%d)->in(%d)): ", i, j); in2_early->dump(); 6486 if (in2->in(0) != nullptr && !in2->in(0)->is_top() && 6487 in2->in(0) != in2_early && !in2->in(0)->is_Root()) { 6488 tty->print("n->in(%d)->in(%d)->in(0): ", i, j); in2->in(0)->dump(); 6489 } 6490 } 6491 } 6492 } 6493 } 6494 tty->cr(); 6495 tty->print("LCA(n): "); LCA->dump(); 6496 for (uint i = 0; i < n->outcnt(); i++) { 6497 Node* u1 = n->raw_out(i); 6498 if (u1 == n) 6499 continue; 6500 tty->print("n->out(%d): ", i); u1->dump(); 6501 if (u1->is_CFG()) { 6502 for (uint j = 0; j < u1->outcnt(); j++) { 6503 Node* u2 = u1->raw_out(j); 6504 if (u2 != u1 && u2 != n && u2->is_CFG()) { 6505 tty->print("n->out(%d)->out(%d): ", i, j); u2->dump(); 6506 } 6507 } 6508 } else { 6509 Node* u1_later = get_ctrl(u1); 6510 tty->print("later(n->out(%d)): ", i); u1_later->dump(); 6511 if (u1->in(0) != nullptr && !u1->in(0)->is_top() && 6512 u1->in(0) != u1_later && !u1->in(0)->is_Root()) { 6513 tty->print("n->out(%d)->in(0): ", i); u1->in(0)->dump(); 6514 } 6515 for (uint j = 0; j < u1->outcnt(); j++) { 6516 Node* u2 = u1->raw_out(j); 6517 if (u2 == n || u2 == u1) 6518 continue; 6519 tty->print("n->out(%d)->out(%d): ", i, j); u2->dump(); 6520 if (!u2->is_CFG()) { 6521 Node* u2_later = get_ctrl(u2); 6522 tty->print("later(n->out(%d)->out(%d)): ", i, j); u2_later->dump(); 6523 if (u2->in(0) != nullptr && !u2->in(0)->is_top() && 6524 u2->in(0) != u2_later && !u2->in(0)->is_Root()) { 6525 tty->print("n->out(%d)->in(0): ", i); u2->in(0)->dump(); 6526 } 6527 } 6528 } 6529 } 6530 } 6531 dump_idoms(early, LCA); 6532 tty->cr(); 6533 } 6534 6535 // Class to compute the real LCA given an early node and a wrong LCA in a bad graph. 6536 class RealLCA { 6537 const PhaseIdealLoop* _phase; 6538 Node* _early; 6539 Node* _wrong_lca; 6540 uint _early_index; 6541 int _wrong_lca_index; 6542 6543 // Given idom chains of early and wrong LCA: Walk through idoms starting at StartNode and find the first node which 6544 // is different: Return the previously visited node which must be the real LCA. 6545 // The node lists also contain _early and _wrong_lca, respectively. 6546 Node* find_real_lca(Unique_Node_List& early_with_idoms, Unique_Node_List& wrong_lca_with_idoms) { 6547 int early_index = early_with_idoms.size() - 1; 6548 int wrong_lca_index = wrong_lca_with_idoms.size() - 1; 6549 bool found_difference = false; 6550 do { 6551 if (early_with_idoms[early_index] != wrong_lca_with_idoms[wrong_lca_index]) { 6552 // First time early and wrong LCA idoms differ. Real LCA must be at the previous index. 6553 found_difference = true; 6554 break; 6555 } 6556 early_index--; 6557 wrong_lca_index--; 6558 } while (wrong_lca_index >= 0); 6559 6560 assert(early_index >= 0, "must always find an LCA - cannot be early"); 6561 _early_index = early_index; 6562 _wrong_lca_index = wrong_lca_index; 6563 Node* real_lca = early_with_idoms[_early_index + 1]; // Plus one to skip _early. 6564 assert(found_difference || real_lca == _wrong_lca, "wrong LCA dominates early and is therefore the real LCA"); 6565 return real_lca; 6566 } 6567 6568 void dump(Node* real_lca) { 6569 tty->cr(); 6570 tty->print_cr("idoms of early \"%d %s\":", _early->_idx, _early->Name()); 6571 _phase->dump_idom(_early, _early_index + 1); 6572 6573 tty->cr(); 6574 tty->print_cr("idoms of (wrong) LCA \"%d %s\":", _wrong_lca->_idx, _wrong_lca->Name()); 6575 _phase->dump_idom(_wrong_lca, _wrong_lca_index + 1); 6576 6577 tty->cr(); 6578 tty->print("Real LCA of early \"%d %s\" (idom[%d]) and wrong LCA \"%d %s\"", 6579 _early->_idx, _early->Name(), _early_index, _wrong_lca->_idx, _wrong_lca->Name()); 6580 if (_wrong_lca_index >= 0) { 6581 tty->print(" (idom[%d])", _wrong_lca_index); 6582 } 6583 tty->print_cr(":"); 6584 real_lca->dump(); 6585 } 6586 6587 public: 6588 RealLCA(const PhaseIdealLoop* phase, Node* early, Node* wrong_lca) 6589 : _phase(phase), _early(early), _wrong_lca(wrong_lca), _early_index(0), _wrong_lca_index(0) { 6590 assert(!wrong_lca->is_Start(), "StartNode is always a common dominator"); 6591 } 6592 6593 void compute_and_dump() { 6594 ResourceMark rm; 6595 Unique_Node_List early_with_idoms; 6596 Unique_Node_List wrong_lca_with_idoms; 6597 early_with_idoms.push(_early); 6598 wrong_lca_with_idoms.push(_wrong_lca); 6599 _phase->get_idoms(_early, 10000, early_with_idoms); 6600 _phase->get_idoms(_wrong_lca, 10000, wrong_lca_with_idoms); 6601 Node* real_lca = find_real_lca(early_with_idoms, wrong_lca_with_idoms); 6602 dump(real_lca); 6603 } 6604 }; 6605 6606 // Dump the idom chain of early, of the wrong LCA and dump the real LCA of early and wrong LCA. 6607 void PhaseIdealLoop::dump_idoms(Node* early, Node* wrong_lca) { 6608 assert(!is_dominator(early, wrong_lca), "sanity check that early does not dominate wrong lca"); 6609 assert(!has_ctrl(early) && !has_ctrl(wrong_lca), "sanity check, no data nodes"); 6610 6611 RealLCA real_lca(this, early, wrong_lca); 6612 real_lca.compute_and_dump(); 6613 } 6614 #endif // ASSERT 6615 6616 #ifndef PRODUCT 6617 //------------------------------dump------------------------------------------- 6618 void PhaseIdealLoop::dump() const { 6619 ResourceMark rm; 6620 Node_Stack stack(C->live_nodes() >> 2); 6621 Node_List rpo_list; 6622 VectorSet visited; 6623 visited.set(C->top()->_idx); 6624 rpo(C->root(), stack, visited, rpo_list); 6625 // Dump root loop indexed by last element in PO order 6626 dump(_ltree_root, rpo_list.size(), rpo_list); 6627 } 6628 6629 void PhaseIdealLoop::dump(IdealLoopTree* loop, uint idx, Node_List &rpo_list) const { 6630 loop->dump_head(); 6631 6632 // Now scan for CFG nodes in the same loop 6633 for (uint j = idx; j > 0; j--) { 6634 Node* n = rpo_list[j-1]; 6635 if (!_loop_or_ctrl[n->_idx]) // Skip dead nodes 6636 continue; 6637 6638 if (get_loop(n) != loop) { // Wrong loop nest 6639 if (get_loop(n)->_head == n && // Found nested loop? 6640 get_loop(n)->_parent == loop) 6641 dump(get_loop(n), rpo_list.size(), rpo_list); // Print it nested-ly 6642 continue; 6643 } 6644 6645 // Dump controlling node 6646 tty->sp(2 * loop->_nest); 6647 tty->print("C"); 6648 if (n == C->root()) { 6649 n->dump(); 6650 } else { 6651 Node* cached_idom = idom_no_update(n); 6652 Node* computed_idom = n->in(0); 6653 if (n->is_Region()) { 6654 computed_idom = compute_idom(n); 6655 // computed_idom() will return n->in(0) when idom(n) is an IfNode (or 6656 // any MultiBranch ctrl node), so apply a similar transform to 6657 // the cached idom returned from idom_no_update. 6658 cached_idom = find_non_split_ctrl(cached_idom); 6659 } 6660 tty->print(" ID:%d", computed_idom->_idx); 6661 n->dump(); 6662 if (cached_idom != computed_idom) { 6663 tty->print_cr("*** BROKEN IDOM! Computed as: %d, cached as: %d", 6664 computed_idom->_idx, cached_idom->_idx); 6665 } 6666 } 6667 // Dump nodes it controls 6668 for (uint k = 0; k < _loop_or_ctrl.max(); k++) { 6669 // (k < C->unique() && get_ctrl(find(k)) == n) 6670 if (k < C->unique() && _loop_or_ctrl[k] == (Node*)((intptr_t)n + 1)) { 6671 Node* m = C->root()->find(k); 6672 if (m && m->outcnt() > 0) { 6673 if (!(has_ctrl(m) && get_ctrl_no_update(m) == n)) { 6674 tty->print_cr("*** BROKEN CTRL ACCESSOR! _loop_or_ctrl[k] is %p, ctrl is %p", 6675 _loop_or_ctrl[k], has_ctrl(m) ? get_ctrl_no_update(m) : nullptr); 6676 } 6677 tty->sp(2 * loop->_nest + 1); 6678 m->dump(); 6679 } 6680 } 6681 } 6682 } 6683 } 6684 6685 void PhaseIdealLoop::dump_idom(Node* n, const uint count) const { 6686 if (has_ctrl(n)) { 6687 tty->print_cr("No idom for data nodes"); 6688 } else { 6689 ResourceMark rm; 6690 Unique_Node_List idoms; 6691 get_idoms(n, count, idoms); 6692 dump_idoms_in_reverse(n, idoms); 6693 } 6694 } 6695 6696 void PhaseIdealLoop::get_idoms(Node* n, const uint count, Unique_Node_List& idoms) const { 6697 Node* next = n; 6698 for (uint i = 0; !next->is_Start() && i < count; i++) { 6699 next = idom(next); 6700 assert(!idoms.member(next), "duplicated idom is not possible"); 6701 idoms.push(next); 6702 } 6703 } 6704 6705 void PhaseIdealLoop::dump_idoms_in_reverse(const Node* n, const Node_List& idom_list) const { 6706 Node* next; 6707 uint padding = 3; 6708 uint node_index_padding_width = static_cast<int>(log10(static_cast<double>(C->unique()))) + 1; 6709 for (int i = idom_list.size() - 1; i >= 0; i--) { 6710 if (i == 9 || i == 99) { 6711 padding++; 6712 } 6713 next = idom_list[i]; 6714 tty->print_cr("idom[%d]:%*c%*d %s", i, padding, ' ', node_index_padding_width, next->_idx, next->Name()); 6715 } 6716 tty->print_cr("n: %*c%*d %s", padding, ' ', node_index_padding_width, n->_idx, n->Name()); 6717 } 6718 #endif // NOT PRODUCT 6719 6720 // Collect a R-P-O for the whole CFG. 6721 // Result list is in post-order (scan backwards for RPO) 6722 void PhaseIdealLoop::rpo(Node* start, Node_Stack &stk, VectorSet &visited, Node_List &rpo_list) const { 6723 stk.push(start, 0); 6724 visited.set(start->_idx); 6725 6726 while (stk.is_nonempty()) { 6727 Node* m = stk.node(); 6728 uint idx = stk.index(); 6729 if (idx < m->outcnt()) { 6730 stk.set_index(idx + 1); 6731 Node* n = m->raw_out(idx); 6732 if (n->is_CFG() && !visited.test_set(n->_idx)) { 6733 stk.push(n, 0); 6734 } 6735 } else { 6736 rpo_list.push(m); 6737 stk.pop(); 6738 } 6739 } 6740 } 6741 6742 6743 //============================================================================= 6744 //------------------------------LoopTreeIterator------------------------------- 6745 6746 // Advance to next loop tree using a preorder, left-to-right traversal. 6747 void LoopTreeIterator::next() { 6748 assert(!done(), "must not be done."); 6749 if (_curnt->_child != nullptr) { 6750 _curnt = _curnt->_child; 6751 } else if (_curnt->_next != nullptr) { 6752 _curnt = _curnt->_next; 6753 } else { 6754 while (_curnt != _root && _curnt->_next == nullptr) { 6755 _curnt = _curnt->_parent; 6756 } 6757 if (_curnt == _root) { 6758 _curnt = nullptr; 6759 assert(done(), "must be done."); 6760 } else { 6761 assert(_curnt->_next != nullptr, "must be more to do"); 6762 _curnt = _curnt->_next; 6763 } 6764 } 6765 }