1 /* 2 * Copyright (c) 1998, 2020, 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/connode.hpp" 37 #include "opto/convertnode.hpp" 38 #include "opto/divnode.hpp" 39 #include "opto/idealGraphPrinter.hpp" 40 #include "opto/loopnode.hpp" 41 #include "opto/movenode.hpp" 42 #include "opto/mulnode.hpp" 43 #include "opto/rootnode.hpp" 44 #include "opto/superword.hpp" 45 #include "utilities/powerOfTwo.hpp" 46 47 //============================================================================= 48 //--------------------------is_cloop_ind_var----------------------------------- 49 // Determine if a node is a counted loop induction variable. 50 // NOTE: The method is declared in "node.hpp". 51 bool Node::is_cloop_ind_var() const { 52 return (is_Phi() && !as_Phi()->is_copy() && 53 as_Phi()->region()->is_CountedLoop() && 54 as_Phi()->region()->as_CountedLoop()->phi() == this); 55 } 56 57 //============================================================================= 58 //------------------------------dump_spec-------------------------------------- 59 // Dump special per-node info 60 #ifndef PRODUCT 61 void LoopNode::dump_spec(outputStream *st) const { 62 if (is_inner_loop()) st->print( "inner " ); 63 if (is_partial_peel_loop()) st->print( "partial_peel " ); 64 if (partial_peel_has_failed()) st->print( "partial_peel_failed " ); 65 } 66 #endif 67 68 //------------------------------is_valid_counted_loop------------------------- 69 bool LoopNode::is_valid_counted_loop() const { 70 if (is_CountedLoop()) { 71 CountedLoopNode* l = as_CountedLoop(); 72 CountedLoopEndNode* le = l->loopexit_or_null(); 73 if (le != NULL && 74 le->proj_out_or_null(1 /* true */) == l->in(LoopNode::LoopBackControl)) { 75 Node* phi = l->phi(); 76 Node* exit = le->proj_out_or_null(0 /* false */); 77 if (exit != NULL && exit->Opcode() == Op_IfFalse && 78 phi != NULL && phi->is_Phi() && 79 phi->in(LoopNode::LoopBackControl) == l->incr() && 80 le->loopnode() == l && le->stride_is_con()) { 81 return true; 82 } 83 } 84 } 85 return false; 86 } 87 88 //------------------------------get_early_ctrl--------------------------------- 89 // Compute earliest legal control 90 Node *PhaseIdealLoop::get_early_ctrl( Node *n ) { 91 assert( !n->is_Phi() && !n->is_CFG(), "this code only handles data nodes" ); 92 uint i; 93 Node *early; 94 if (n->in(0) && !n->is_expensive()) { 95 early = n->in(0); 96 if (!early->is_CFG()) // Might be a non-CFG multi-def 97 early = get_ctrl(early); // So treat input as a straight data input 98 i = 1; 99 } else { 100 early = get_ctrl(n->in(1)); 101 i = 2; 102 } 103 uint e_d = dom_depth(early); 104 assert( early, "" ); 105 for (; i < n->req(); i++) { 106 Node *cin = get_ctrl(n->in(i)); 107 assert( cin, "" ); 108 // Keep deepest dominator depth 109 uint c_d = dom_depth(cin); 110 if (c_d > e_d) { // Deeper guy? 111 early = cin; // Keep deepest found so far 112 e_d = c_d; 113 } else if (c_d == e_d && // Same depth? 114 early != cin) { // If not equal, must use slower algorithm 115 // If same depth but not equal, one _must_ dominate the other 116 // and we want the deeper (i.e., dominated) guy. 117 Node *n1 = early; 118 Node *n2 = cin; 119 while (1) { 120 n1 = idom(n1); // Walk up until break cycle 121 n2 = idom(n2); 122 if (n1 == cin || // Walked early up to cin 123 dom_depth(n2) < c_d) 124 break; // early is deeper; keep him 125 if (n2 == early || // Walked cin up to early 126 dom_depth(n1) < c_d) { 127 early = cin; // cin is deeper; keep him 128 break; 129 } 130 } 131 e_d = dom_depth(early); // Reset depth register cache 132 } 133 } 134 135 // Return earliest legal location 136 assert(early == find_non_split_ctrl(early), "unexpected early control"); 137 138 if (n->is_expensive() && !_verify_only && !_verify_me) { 139 assert(n->in(0), "should have control input"); 140 early = get_early_ctrl_for_expensive(n, early); 141 } 142 143 return early; 144 } 145 146 //------------------------------get_early_ctrl_for_expensive--------------------------------- 147 // Move node up the dominator tree as high as legal while still beneficial 148 Node *PhaseIdealLoop::get_early_ctrl_for_expensive(Node *n, Node* earliest) { 149 assert(n->in(0) && n->is_expensive(), "expensive node with control input here"); 150 assert(OptimizeExpensiveOps, "optimization off?"); 151 152 Node* ctl = n->in(0); 153 assert(ctl->is_CFG(), "expensive input 0 must be cfg"); 154 uint min_dom_depth = dom_depth(earliest); 155 #ifdef ASSERT 156 if (!is_dominator(ctl, earliest) && !is_dominator(earliest, ctl)) { 157 dump_bad_graph("Bad graph detected in get_early_ctrl_for_expensive", n, earliest, ctl); 158 assert(false, "Bad graph detected in get_early_ctrl_for_expensive"); 159 } 160 #endif 161 if (dom_depth(ctl) < min_dom_depth) { 162 return earliest; 163 } 164 165 while (1) { 166 Node *next = ctl; 167 // Moving the node out of a loop on the projection of a If 168 // confuses loop predication. So once we hit a Loop in a If branch 169 // that doesn't branch to an UNC, we stop. The code that process 170 // expensive nodes will notice the loop and skip over it to try to 171 // move the node further up. 172 if (ctl->is_CountedLoop() && ctl->in(1) != NULL && ctl->in(1)->in(0) != NULL && ctl->in(1)->in(0)->is_If()) { 173 if (!ctl->in(1)->as_Proj()->is_uncommon_trap_if_pattern(Deoptimization::Reason_none)) { 174 break; 175 } 176 next = idom(ctl->in(1)->in(0)); 177 } else if (ctl->is_Proj()) { 178 // We only move it up along a projection if the projection is 179 // the single control projection for its parent: same code path, 180 // if it's a If with UNC or fallthrough of a call. 181 Node* parent_ctl = ctl->in(0); 182 if (parent_ctl == NULL) { 183 break; 184 } else if (parent_ctl->is_CountedLoopEnd() && parent_ctl->as_CountedLoopEnd()->loopnode() != NULL) { 185 next = parent_ctl->as_CountedLoopEnd()->loopnode()->init_control(); 186 } else if (parent_ctl->is_If()) { 187 if (!ctl->as_Proj()->is_uncommon_trap_if_pattern(Deoptimization::Reason_none)) { 188 break; 189 } 190 assert(idom(ctl) == parent_ctl, "strange"); 191 next = idom(parent_ctl); 192 } else if (ctl->is_CatchProj()) { 193 if (ctl->as_Proj()->_con != CatchProjNode::fall_through_index) { 194 break; 195 } 196 assert(parent_ctl->in(0)->in(0)->is_Call(), "strange graph"); 197 next = parent_ctl->in(0)->in(0)->in(0); 198 } else { 199 // Check if parent control has a single projection (this 200 // control is the only possible successor of the parent 201 // control). If so, we can try to move the node above the 202 // parent control. 203 int nb_ctl_proj = 0; 204 for (DUIterator_Fast imax, i = parent_ctl->fast_outs(imax); i < imax; i++) { 205 Node *p = parent_ctl->fast_out(i); 206 if (p->is_Proj() && p->is_CFG()) { 207 nb_ctl_proj++; 208 if (nb_ctl_proj > 1) { 209 break; 210 } 211 } 212 } 213 214 if (nb_ctl_proj > 1) { 215 break; 216 } 217 assert(parent_ctl->is_Start() || parent_ctl->is_MemBar() || parent_ctl->is_Call() || 218 BarrierSet::barrier_set()->barrier_set_c2()->is_gc_barrier_node(parent_ctl), "unexpected node"); 219 assert(idom(ctl) == parent_ctl, "strange"); 220 next = idom(parent_ctl); 221 } 222 } else { 223 next = idom(ctl); 224 } 225 if (next->is_Root() || next->is_Start() || dom_depth(next) < min_dom_depth) { 226 break; 227 } 228 ctl = next; 229 } 230 231 if (ctl != n->in(0)) { 232 _igvn.replace_input_of(n, 0, ctl); 233 _igvn.hash_insert(n); 234 } 235 236 return ctl; 237 } 238 239 240 //------------------------------set_early_ctrl--------------------------------- 241 // Set earliest legal control 242 void PhaseIdealLoop::set_early_ctrl( Node *n ) { 243 Node *early = get_early_ctrl(n); 244 245 // Record earliest legal location 246 set_ctrl(n, early); 247 } 248 249 //------------------------------set_subtree_ctrl------------------------------- 250 // set missing _ctrl entries on new nodes 251 void PhaseIdealLoop::set_subtree_ctrl( Node *n ) { 252 // Already set? Get out. 253 if( _nodes[n->_idx] ) return; 254 // Recursively set _nodes array to indicate where the Node goes 255 uint i; 256 for( i = 0; i < n->req(); ++i ) { 257 Node *m = n->in(i); 258 if( m && m != C->root() ) 259 set_subtree_ctrl( m ); 260 } 261 262 // Fixup self 263 set_early_ctrl( n ); 264 } 265 266 IdealLoopTree* PhaseIdealLoop::insert_outer_loop(IdealLoopTree* loop, LoopNode* outer_l, Node* outer_ift) { 267 IdealLoopTree* outer_ilt = new IdealLoopTree(this, outer_l, outer_ift); 268 IdealLoopTree* parent = loop->_parent; 269 IdealLoopTree* sibling = parent->_child; 270 if (sibling == loop) { 271 parent->_child = outer_ilt; 272 } else { 273 while (sibling->_next != loop) { 274 sibling = sibling->_next; 275 } 276 sibling->_next = outer_ilt; 277 } 278 outer_ilt->_next = loop->_next; 279 outer_ilt->_parent = parent; 280 outer_ilt->_child = loop; 281 outer_ilt->_nest = loop->_nest; 282 loop->_parent = outer_ilt; 283 loop->_next = NULL; 284 loop->_nest++; 285 return outer_ilt; 286 } 287 288 // Create a skeleton strip mined outer loop: a Loop head before the 289 // inner strip mined loop, a safepoint and an exit condition guarded 290 // by an opaque node after the inner strip mined loop with a backedge 291 // to the loop head. The inner strip mined loop is left as it is. Only 292 // once loop optimizations are over, do we adjust the inner loop exit 293 // condition to limit its number of iterations, set the outer loop 294 // exit condition and add Phis to the outer loop head. Some loop 295 // optimizations that operate on the inner strip mined loop need to be 296 // aware of the outer strip mined loop: loop unswitching needs to 297 // clone the outer loop as well as the inner, unrolling needs to only 298 // clone the inner loop etc. No optimizations need to change the outer 299 // strip mined loop as it is only a skeleton. 300 IdealLoopTree* PhaseIdealLoop::create_outer_strip_mined_loop(BoolNode *test, Node *cmp, Node *init_control, 301 IdealLoopTree* loop, float cl_prob, float le_fcnt, 302 Node*& entry_control, Node*& iffalse) { 303 Node* outer_test = _igvn.intcon(0); 304 set_ctrl(outer_test, C->root()); 305 Node *orig = iffalse; 306 iffalse = iffalse->clone(); 307 _igvn.register_new_node_with_optimizer(iffalse); 308 set_idom(iffalse, idom(orig), dom_depth(orig)); 309 310 IfNode *outer_le = new OuterStripMinedLoopEndNode(iffalse, outer_test, cl_prob, le_fcnt); 311 Node *outer_ift = new IfTrueNode (outer_le); 312 Node* outer_iff = orig; 313 _igvn.replace_input_of(outer_iff, 0, outer_le); 314 315 LoopNode *outer_l = new OuterStripMinedLoopNode(C, init_control, outer_ift); 316 entry_control = outer_l; 317 318 IdealLoopTree* outer_ilt = insert_outer_loop(loop, outer_l, outer_ift); 319 320 set_loop(iffalse, outer_ilt); 321 // When this code runs, loop bodies have not yet been populated. 322 const bool body_populated = false; 323 register_control(outer_le, outer_ilt, iffalse, body_populated); 324 register_control(outer_ift, outer_ilt, outer_le, body_populated); 325 set_idom(outer_iff, outer_le, dom_depth(outer_le)); 326 _igvn.register_new_node_with_optimizer(outer_l); 327 set_loop(outer_l, outer_ilt); 328 set_idom(outer_l, init_control, dom_depth(init_control)+1); 329 330 return outer_ilt; 331 } 332 333 void PhaseIdealLoop::insert_loop_limit_check(ProjNode* limit_check_proj, Node* cmp_limit, Node* bol) { 334 Node* new_predicate_proj = create_new_if_for_predicate(limit_check_proj, NULL, 335 Deoptimization::Reason_loop_limit_check, 336 Op_If); 337 Node* iff = new_predicate_proj->in(0); 338 assert(iff->Opcode() == Op_If, "bad graph shape"); 339 Node* conv = iff->in(1); 340 assert(conv->Opcode() == Op_Conv2B, "bad graph shape"); 341 Node* opaq = conv->in(1); 342 assert(opaq->Opcode() == Op_Opaque1, "bad graph shape"); 343 cmp_limit = _igvn.register_new_node_with_optimizer(cmp_limit); 344 bol = _igvn.register_new_node_with_optimizer(bol); 345 set_subtree_ctrl(bol); 346 _igvn.replace_input_of(iff, 1, bol); 347 348 #ifndef PRODUCT 349 // report that the loop predication has been actually performed 350 // for this loop 351 if (TraceLoopLimitCheck) { 352 tty->print_cr("Counted Loop Limit Check generated:"); 353 debug_only( bol->dump(2); ) 354 } 355 #endif 356 } 357 358 Node* PhaseIdealLoop::loop_exit_control(Node* x, IdealLoopTree* loop) { 359 // Counted loop head must be a good RegionNode with only 3 not NULL 360 // control input edges: Self, Entry, LoopBack. 361 if (x->in(LoopNode::Self) == NULL || x->req() != 3 || loop->_irreducible) { 362 return NULL; 363 } 364 Node *init_control = x->in(LoopNode::EntryControl); 365 Node *back_control = x->in(LoopNode::LoopBackControl); 366 if (init_control == NULL || back_control == NULL) { // Partially dead 367 return NULL; 368 } 369 // Must also check for TOP when looking for a dead loop 370 if (init_control->is_top() || back_control->is_top()) { 371 return NULL; 372 } 373 374 // Allow funny placement of Safepoint 375 if (back_control->Opcode() == Op_SafePoint) { 376 back_control = back_control->in(TypeFunc::Control); 377 } 378 379 // Controlling test for loop 380 Node *iftrue = back_control; 381 uint iftrue_op = iftrue->Opcode(); 382 if (iftrue_op != Op_IfTrue && 383 iftrue_op != Op_IfFalse) { 384 // I have a weird back-control. Probably the loop-exit test is in 385 // the middle of the loop and I am looking at some trailing control-flow 386 // merge point. To fix this I would have to partially peel the loop. 387 return NULL; // Obscure back-control 388 } 389 390 // Get boolean guarding loop-back test 391 Node *iff = iftrue->in(0); 392 if (get_loop(iff) != loop || !iff->in(1)->is_Bool()) { 393 return NULL; 394 } 395 return iftrue; 396 } 397 398 Node* PhaseIdealLoop::loop_exit_test(Node* back_control, IdealLoopTree* loop, Node*& incr, Node*& limit, BoolTest::mask& bt, float& cl_prob) { 399 Node* iftrue = back_control; 400 uint iftrue_op = iftrue->Opcode(); 401 Node* iff = iftrue->in(0); 402 BoolNode* test = iff->in(1)->as_Bool(); 403 bt = test->_test._test; 404 cl_prob = iff->as_If()->_prob; 405 if (iftrue_op == Op_IfFalse) { 406 bt = BoolTest(bt).negate(); 407 cl_prob = 1.0 - cl_prob; 408 } 409 // Get backedge compare 410 Node* cmp = test->in(1); 411 if (!cmp->is_Cmp()) { 412 return NULL; 413 } 414 415 // Find the trip-counter increment & limit. Limit must be loop invariant. 416 incr = cmp->in(1); 417 limit = cmp->in(2); 418 419 // --------- 420 // need 'loop()' test to tell if limit is loop invariant 421 // --------- 422 423 if (!is_member(loop, get_ctrl(incr))) { // Swapped trip counter and limit? 424 Node* tmp = incr; // Then reverse order into the CmpI 425 incr = limit; 426 limit = tmp; 427 bt = BoolTest(bt).commute(); // And commute the exit test 428 } 429 if (is_member(loop, get_ctrl(limit))) { // Limit must be loop-invariant 430 return NULL; 431 } 432 if (!is_member(loop, get_ctrl(incr))) { // Trip counter must be loop-variant 433 return NULL; 434 } 435 return cmp; 436 } 437 438 Node* PhaseIdealLoop::loop_iv_incr(Node* incr, Node* x, IdealLoopTree* loop, Node*& phi_incr) { 439 if (incr->is_Phi()) { 440 if (incr->as_Phi()->region() != x || incr->req() != 3) { 441 return NULL; // Not simple trip counter expression 442 } 443 phi_incr = incr; 444 incr = phi_incr->in(LoopNode::LoopBackControl); // Assume incr is on backedge of Phi 445 if (!is_member(loop, get_ctrl(incr))) { // Trip counter must be loop-variant 446 return NULL; 447 } 448 } 449 return incr; 450 } 451 452 Node* PhaseIdealLoop::loop_iv_stride(Node* incr, IdealLoopTree* loop, Node*& xphi) { 453 assert(incr->Opcode() == Op_AddI || incr->Opcode() == Op_AddL, "caller resp."); 454 // Get merge point 455 xphi = incr->in(1); 456 Node *stride = incr->in(2); 457 if (!stride->is_Con()) { // Oops, swap these 458 if (!xphi->is_Con()) { // Is the other guy a constant? 459 return NULL; // Nope, unknown stride, bail out 460 } 461 Node *tmp = xphi; // 'incr' is commutative, so ok to swap 462 xphi = stride; 463 stride = tmp; 464 } 465 return stride; 466 } 467 468 PhiNode* PhaseIdealLoop::loop_iv_phi(Node* xphi, Node* phi_incr, Node* x, IdealLoopTree* loop) { 469 if (!xphi->is_Phi()) { 470 return NULL; // Too much math on the trip counter 471 } 472 if (phi_incr != NULL && phi_incr != xphi) { 473 return NULL; 474 } 475 PhiNode *phi = xphi->as_Phi(); 476 477 // Phi must be of loop header; backedge must wrap to increment 478 if (phi->region() != x) { 479 return NULL; 480 } 481 return phi; 482 } 483 484 // Return 0 if it won't overflow, -1 if it must overflow, and 1 otherwise. 485 static int check_stride_overflow(jint stride_con, const TypeInt* limit_t) { 486 if (stride_con > 0) { 487 if (limit_t->_lo > (max_jint - stride_con)) { 488 return -1; 489 } 490 if (limit_t->_hi > (max_jint - stride_con)) { 491 return 1; 492 } 493 } else { 494 if (limit_t->_hi < (min_jint - stride_con)) { 495 return -1; 496 } 497 if (limit_t->_lo < (min_jint - stride_con)) { 498 return 1; 499 } 500 } 501 return 0; 502 } 503 504 //------------------------------is_counted_loop-------------------------------- 505 bool PhaseIdealLoop::is_counted_loop(Node* x, IdealLoopTree*& loop) { 506 PhaseGVN *gvn = &_igvn; 507 508 Node* back_control = loop_exit_control(x, loop); 509 if (back_control == NULL) { 510 return false; 511 } 512 513 BoolTest::mask bt = BoolTest::illegal; 514 float cl_prob = 0; 515 Node* incr = NULL; 516 Node* limit = NULL; 517 518 Node* cmp = loop_exit_test(back_control, loop, incr, limit, bt, cl_prob); 519 if (cmp == NULL || cmp->Opcode() != Op_CmpI) { 520 return false; // Avoid pointer & float & 64-bit compares 521 } 522 523 // Trip-counter increment must be commutative & associative. 524 if (incr->Opcode() == Op_CastII) { 525 incr = incr->in(1); 526 } 527 528 Node* phi_incr = NULL; 529 incr = loop_iv_incr(incr, x, loop, phi_incr); 530 if (incr == NULL) { 531 return false; 532 } 533 534 Node* trunc1 = NULL; 535 Node* trunc2 = NULL; 536 const TypeInt* iv_trunc_t = NULL; 537 Node* orig_incr = incr; 538 if (!(incr = CountedLoopNode::match_incr_with_optional_truncation(incr, &trunc1, &trunc2, &iv_trunc_t))) { 539 return false; // Funny increment opcode 540 } 541 assert(incr->Opcode() == Op_AddI, "wrong increment code"); 542 543 Node* xphi = NULL; 544 Node* stride = loop_iv_stride(incr, loop, xphi); 545 546 if (stride == NULL) { 547 return false; 548 } 549 550 if (xphi->Opcode() == Op_CastII) { 551 xphi = xphi->in(1); 552 } 553 554 // Stride must be constant 555 int stride_con = stride->get_int(); 556 assert(stride_con != 0, "missed some peephole opt"); 557 558 PhiNode* phi = loop_iv_phi(xphi, phi_incr, x, loop); 559 560 if (phi == NULL || 561 (trunc1 == NULL && phi->in(LoopNode::LoopBackControl) != incr) || 562 (trunc1 != NULL && phi->in(LoopNode::LoopBackControl) != trunc1)) { 563 return false; 564 } 565 566 if (x->in(LoopNode::LoopBackControl)->Opcode() == Op_SafePoint && 567 LoopStripMiningIter != 0) { 568 // Leaving the safepoint on the backedge and creating a 569 // CountedLoop will confuse optimizations. We can't move the 570 // safepoint around because its jvm state wouldn't match a new 571 // location. Give up on that loop. 572 return false; 573 } 574 575 Node* iftrue = back_control; 576 uint iftrue_op = iftrue->Opcode(); 577 Node* iff = iftrue->in(0); 578 BoolNode* test = iff->in(1)->as_Bool(); 579 580 const TypeInt* limit_t = gvn->type(limit)->is_int(); 581 if (trunc1 != NULL) { 582 // When there is a truncation, we must be sure that after the truncation 583 // the trip counter will end up higher than the limit, otherwise we are looking 584 // at an endless loop. Can happen with range checks. 585 586 // Example: 587 // int i = 0; 588 // while (true) 589 // sum + = array[i]; 590 // i++; 591 // i = i && 0x7fff; 592 // } 593 // 594 // If the array is shorter than 0x8000 this exits through a AIOOB 595 // - Counted loop transformation is ok 596 // If the array is longer then this is an endless loop 597 // - No transformation can be done. 598 599 const TypeInt* incr_t = gvn->type(orig_incr)->is_int(); 600 if (limit_t->_hi > incr_t->_hi) { 601 // if the limit can have a higher value than the increment (before the phi) 602 return false; 603 } 604 } 605 606 Node *init_trip = phi->in(LoopNode::EntryControl); 607 608 // If iv trunc type is smaller than int, check for possible wrap. 609 if (!TypeInt::INT->higher_equal(iv_trunc_t)) { 610 assert(trunc1 != NULL, "must have found some truncation"); 611 612 // Get a better type for the phi (filtered thru if's) 613 const TypeInt* phi_ft = filtered_type(phi); 614 615 // Can iv take on a value that will wrap? 616 // 617 // Ensure iv's limit is not within "stride" of the wrap value. 618 // 619 // Example for "short" type 620 // Truncation ensures value is in the range -32768..32767 (iv_trunc_t) 621 // If the stride is +10, then the last value of the induction 622 // variable before the increment (phi_ft->_hi) must be 623 // <= 32767 - 10 and (phi_ft->_lo) must be >= -32768 to 624 // ensure no truncation occurs after the increment. 625 626 if (stride_con > 0) { 627 if (iv_trunc_t->_hi - phi_ft->_hi < stride_con || 628 iv_trunc_t->_lo > phi_ft->_lo) { 629 return false; // truncation may occur 630 } 631 } else if (stride_con < 0) { 632 if (iv_trunc_t->_lo - phi_ft->_lo > stride_con || 633 iv_trunc_t->_hi < phi_ft->_hi) { 634 return false; // truncation may occur 635 } 636 } 637 // No possibility of wrap so truncation can be discarded 638 // Promote iv type to Int 639 } else { 640 assert(trunc1 == NULL && trunc2 == NULL, "no truncation for int"); 641 } 642 643 // If the condition is inverted and we will be rolling 644 // through MININT to MAXINT, then bail out. 645 if (bt == BoolTest::eq || // Bail out, but this loop trips at most twice! 646 // Odd stride 647 (bt == BoolTest::ne && stride_con != 1 && stride_con != -1) || 648 // Count down loop rolls through MAXINT 649 ((bt == BoolTest::le || bt == BoolTest::lt) && stride_con < 0) || 650 // Count up loop rolls through MININT 651 ((bt == BoolTest::ge || bt == BoolTest::gt) && stride_con > 0)) { 652 return false; // Bail out 653 } 654 655 const TypeInt* init_t = gvn->type(init_trip)->is_int(); 656 657 if (stride_con > 0) { 658 jlong init_p = (jlong)init_t->_lo + stride_con; 659 if (init_p > (jlong)max_jint || init_p > (jlong)limit_t->_hi) 660 return false; // cyclic loop or this loop trips only once 661 } else { 662 jlong init_p = (jlong)init_t->_hi + stride_con; 663 if (init_p < (jlong)min_jint || init_p < (jlong)limit_t->_lo) 664 return false; // cyclic loop or this loop trips only once 665 } 666 667 if (phi_incr != NULL && bt != BoolTest::ne) { 668 // check if there is a possiblity of IV overflowing after the first increment 669 if (stride_con > 0) { 670 if (init_t->_hi > max_jint - stride_con) { 671 return false; 672 } 673 } else { 674 if (init_t->_lo < min_jint - stride_con) { 675 return false; 676 } 677 } 678 } 679 680 // ================================================= 681 // ---- SUCCESS! Found A Trip-Counted Loop! ----- 682 // 683 assert(x->Opcode() == Op_Loop, "regular loops only"); 684 C->print_method(PHASE_BEFORE_CLOOPS, 3); 685 686 Node *hook = new Node(6); 687 688 // =================================================== 689 // Generate loop limit check to avoid integer overflow 690 // in cases like next (cyclic loops): 691 // 692 // for (i=0; i <= max_jint; i++) {} 693 // for (i=0; i < max_jint; i+=2) {} 694 // 695 // 696 // Limit check predicate depends on the loop test: 697 // 698 // for(;i != limit; i++) --> limit <= (max_jint) 699 // for(;i < limit; i+=stride) --> limit <= (max_jint - stride + 1) 700 // for(;i <= limit; i+=stride) --> limit <= (max_jint - stride ) 701 // 702 703 // Check if limit is excluded to do more precise int overflow check. 704 bool incl_limit = (bt == BoolTest::le || bt == BoolTest::ge); 705 int stride_m = stride_con - (incl_limit ? 0 : (stride_con > 0 ? 1 : -1)); 706 707 // If compare points directly to the phi we need to adjust 708 // the compare so that it points to the incr. Limit have 709 // to be adjusted to keep trip count the same and the 710 // adjusted limit should be checked for int overflow. 711 Node* adjusted_limit = limit; 712 if (phi_incr != NULL) { 713 stride_m += stride_con; 714 } 715 716 Node *init_control = x->in(LoopNode::EntryControl); 717 718 int sov = check_stride_overflow(stride_m, limit_t); 719 // If sov==0, limit's type always satisfies the condition, for 720 // example, when it is an array length. 721 if (sov != 0) { 722 if (sov < 0) { 723 return false; // Bailout: integer overflow is certain. 724 } 725 // Generate loop's limit check. 726 // Loop limit check predicate should be near the loop. 727 ProjNode *limit_check_proj = find_predicate_insertion_point(init_control, Deoptimization::Reason_loop_limit_check); 728 if (!limit_check_proj) { 729 // The limit check predicate is not generated if this method trapped here before. 730 #ifdef ASSERT 731 if (TraceLoopLimitCheck) { 732 tty->print("missing loop limit check:"); 733 loop->dump_head(); 734 x->dump(1); 735 } 736 #endif 737 return false; 738 } 739 740 IfNode* check_iff = limit_check_proj->in(0)->as_If(); 741 742 if (!is_dominator(get_ctrl(limit), check_iff->in(0))) { 743 return false; 744 } 745 746 Node* cmp_limit; 747 Node* bol; 748 749 if (stride_con > 0) { 750 cmp_limit = new CmpINode(limit, _igvn.intcon(max_jint - stride_m)); 751 bol = new BoolNode(cmp_limit, BoolTest::le); 752 } else { 753 cmp_limit = new CmpINode(limit, _igvn.intcon(min_jint - stride_m)); 754 bol = new BoolNode(cmp_limit, BoolTest::ge); 755 } 756 757 insert_loop_limit_check(limit_check_proj, cmp_limit, bol); 758 } 759 760 // Now we need to canonicalize loop condition. 761 if (bt == BoolTest::ne) { 762 assert(stride_con == 1 || stride_con == -1, "simple increment only"); 763 if (stride_con > 0 && init_t->_hi < limit_t->_lo) { 764 // 'ne' can be replaced with 'lt' only when init < limit. 765 bt = BoolTest::lt; 766 } else if (stride_con < 0 && init_t->_lo > limit_t->_hi) { 767 // 'ne' can be replaced with 'gt' only when init > limit. 768 bt = BoolTest::gt; 769 } else { 770 ProjNode *limit_check_proj = find_predicate_insertion_point(init_control, Deoptimization::Reason_loop_limit_check); 771 if (!limit_check_proj) { 772 // The limit check predicate is not generated if this method trapped here before. 773 #ifdef ASSERT 774 if (TraceLoopLimitCheck) { 775 tty->print("missing loop limit check:"); 776 loop->dump_head(); 777 x->dump(1); 778 } 779 #endif 780 return false; 781 } 782 IfNode* check_iff = limit_check_proj->in(0)->as_If(); 783 784 if (!is_dominator(get_ctrl(limit), check_iff->in(0)) || 785 !is_dominator(get_ctrl(init_trip), check_iff->in(0))) { 786 return false; 787 } 788 789 Node* cmp_limit; 790 Node* bol; 791 792 if (stride_con > 0) { 793 cmp_limit = new CmpINode(init_trip, limit); 794 bol = new BoolNode(cmp_limit, BoolTest::lt); 795 } else { 796 cmp_limit = new CmpINode(init_trip, limit); 797 bol = new BoolNode(cmp_limit, BoolTest::gt); 798 } 799 800 insert_loop_limit_check(limit_check_proj, cmp_limit, bol); 801 802 if (stride_con > 0) { 803 // 'ne' can be replaced with 'lt' only when init < limit. 804 bt = BoolTest::lt; 805 } else if (stride_con < 0) { 806 // 'ne' can be replaced with 'gt' only when init > limit. 807 bt = BoolTest::gt; 808 } 809 } 810 } 811 812 if (phi_incr != NULL) { 813 // If compare points directly to the phi we need to adjust 814 // the compare so that it points to the incr. Limit have 815 // to be adjusted to keep trip count the same and we 816 // should avoid int overflow. 817 // 818 // i = init; do {} while(i++ < limit); 819 // is converted to 820 // i = init; do {} while(++i < limit+1); 821 // 822 adjusted_limit = gvn->transform(new AddINode(limit, stride)); 823 } 824 825 if (incl_limit) { 826 // The limit check guaranties that 'limit <= (max_jint - stride)' so 827 // we can convert 'i <= limit' to 'i < limit+1' since stride != 0. 828 // 829 Node* one = (stride_con > 0) ? gvn->intcon( 1) : gvn->intcon(-1); 830 adjusted_limit = gvn->transform(new AddINode(adjusted_limit, one)); 831 if (bt == BoolTest::le) 832 bt = BoolTest::lt; 833 else if (bt == BoolTest::ge) 834 bt = BoolTest::gt; 835 else 836 ShouldNotReachHere(); 837 } 838 set_subtree_ctrl(adjusted_limit); 839 840 if (LoopStripMiningIter == 0) { 841 // Check for SafePoint on backedge and remove 842 Node *sfpt = x->in(LoopNode::LoopBackControl); 843 if (sfpt->Opcode() == Op_SafePoint && is_deleteable_safept(sfpt)) { 844 lazy_replace( sfpt, iftrue ); 845 if (loop->_safepts != NULL) { 846 loop->_safepts->yank(sfpt); 847 } 848 loop->_tail = iftrue; 849 } 850 } 851 852 // Build a canonical trip test. 853 // Clone code, as old values may be in use. 854 incr = incr->clone(); 855 incr->set_req(1,phi); 856 incr->set_req(2,stride); 857 incr = _igvn.register_new_node_with_optimizer(incr); 858 set_early_ctrl( incr ); 859 _igvn.rehash_node_delayed(phi); 860 phi->set_req_X( LoopNode::LoopBackControl, incr, &_igvn ); 861 862 // If phi type is more restrictive than Int, raise to 863 // Int to prevent (almost) infinite recursion in igvn 864 // which can only handle integer types for constants or minint..maxint. 865 if (!TypeInt::INT->higher_equal(phi->bottom_type())) { 866 Node* nphi = PhiNode::make(phi->in(0), phi->in(LoopNode::EntryControl), TypeInt::INT); 867 nphi->set_req(LoopNode::LoopBackControl, phi->in(LoopNode::LoopBackControl)); 868 nphi = _igvn.register_new_node_with_optimizer(nphi); 869 set_ctrl(nphi, get_ctrl(phi)); 870 _igvn.replace_node(phi, nphi); 871 phi = nphi->as_Phi(); 872 } 873 cmp = cmp->clone(); 874 cmp->set_req(1,incr); 875 cmp->set_req(2, adjusted_limit); 876 cmp = _igvn.register_new_node_with_optimizer(cmp); 877 set_ctrl(cmp, iff->in(0)); 878 879 test = test->clone()->as_Bool(); 880 (*(BoolTest*)&test->_test)._test = bt; 881 test->set_req(1,cmp); 882 _igvn.register_new_node_with_optimizer(test); 883 set_ctrl(test, iff->in(0)); 884 885 // Replace the old IfNode with a new LoopEndNode 886 Node *lex = _igvn.register_new_node_with_optimizer(new CountedLoopEndNode( iff->in(0), test, cl_prob, iff->as_If()->_fcnt )); 887 IfNode *le = lex->as_If(); 888 uint dd = dom_depth(iff); 889 set_idom(le, le->in(0), dd); // Update dominance for loop exit 890 set_loop(le, loop); 891 892 // Get the loop-exit control 893 Node *iffalse = iff->as_If()->proj_out(!(iftrue_op == Op_IfTrue)); 894 895 // Need to swap loop-exit and loop-back control? 896 if (iftrue_op == Op_IfFalse) { 897 Node *ift2=_igvn.register_new_node_with_optimizer(new IfTrueNode (le)); 898 Node *iff2=_igvn.register_new_node_with_optimizer(new IfFalseNode(le)); 899 900 loop->_tail = back_control = ift2; 901 set_loop(ift2, loop); 902 set_loop(iff2, get_loop(iffalse)); 903 904 // Lazy update of 'get_ctrl' mechanism. 905 lazy_replace(iffalse, iff2); 906 lazy_replace(iftrue, ift2); 907 908 // Swap names 909 iffalse = iff2; 910 iftrue = ift2; 911 } else { 912 _igvn.rehash_node_delayed(iffalse); 913 _igvn.rehash_node_delayed(iftrue); 914 iffalse->set_req_X( 0, le, &_igvn ); 915 iftrue ->set_req_X( 0, le, &_igvn ); 916 } 917 918 set_idom(iftrue, le, dd+1); 919 set_idom(iffalse, le, dd+1); 920 assert(iff->outcnt() == 0, "should be dead now"); 921 lazy_replace( iff, le ); // fix 'get_ctrl' 922 923 Node *sfpt2 = le->in(0); 924 925 Node* entry_control = init_control; 926 bool strip_mine_loop = LoopStripMiningIter > 1 && loop->_child == NULL && 927 sfpt2->Opcode() == Op_SafePoint && !loop->_has_call; 928 IdealLoopTree* outer_ilt = NULL; 929 if (strip_mine_loop) { 930 outer_ilt = create_outer_strip_mined_loop(test, cmp, init_control, loop, 931 cl_prob, le->_fcnt, entry_control, 932 iffalse); 933 } 934 935 // Now setup a new CountedLoopNode to replace the existing LoopNode 936 CountedLoopNode *l = new CountedLoopNode(entry_control, back_control); 937 l->set_unswitch_count(x->as_Loop()->unswitch_count()); // Preserve 938 // The following assert is approximately true, and defines the intention 939 // of can_be_counted_loop. It fails, however, because phase->type 940 // is not yet initialized for this loop and its parts. 941 //assert(l->can_be_counted_loop(this), "sanity"); 942 _igvn.register_new_node_with_optimizer(l); 943 set_loop(l, loop); 944 loop->_head = l; 945 // Fix all data nodes placed at the old loop head. 946 // Uses the lazy-update mechanism of 'get_ctrl'. 947 lazy_replace( x, l ); 948 set_idom(l, entry_control, dom_depth(entry_control) + 1); 949 950 if (LoopStripMiningIter == 0 || strip_mine_loop) { 951 // Check for immediately preceding SafePoint and remove 952 if (sfpt2->Opcode() == Op_SafePoint && (LoopStripMiningIter != 0 || is_deleteable_safept(sfpt2))) { 953 if (strip_mine_loop) { 954 Node* outer_le = outer_ilt->_tail->in(0); 955 Node* sfpt = sfpt2->clone(); 956 sfpt->set_req(0, iffalse); 957 outer_le->set_req(0, sfpt); 958 // When this code runs, loop bodies have not yet been populated. 959 const bool body_populated = false; 960 register_control(sfpt, outer_ilt, iffalse, body_populated); 961 set_idom(outer_le, sfpt, dom_depth(sfpt)); 962 } 963 lazy_replace( sfpt2, sfpt2->in(TypeFunc::Control)); 964 if (loop->_safepts != NULL) { 965 loop->_safepts->yank(sfpt2); 966 } 967 } 968 } 969 970 // Free up intermediate goo 971 _igvn.remove_dead_node(hook); 972 973 #ifdef ASSERT 974 assert(l->is_valid_counted_loop(), "counted loop shape is messed up"); 975 assert(l == loop->_head && l->phi() == phi && l->loopexit_or_null() == lex, "" ); 976 #endif 977 #ifndef PRODUCT 978 if (TraceLoopOpts) { 979 tty->print("Counted "); 980 loop->dump_head(); 981 } 982 #endif 983 984 C->print_method(PHASE_AFTER_CLOOPS, 3); 985 986 // Capture bounds of the loop in the induction variable Phi before 987 // subsequent transformation (iteration splitting) obscures the 988 // bounds 989 l->phi()->as_Phi()->set_type(l->phi()->Value(&_igvn)); 990 991 if (strip_mine_loop) { 992 l->mark_strip_mined(); 993 l->verify_strip_mined(1); 994 outer_ilt->_head->as_Loop()->verify_strip_mined(1); 995 loop = outer_ilt; 996 } 997 998 return true; 999 } 1000 1001 //----------------------exact_limit------------------------------------------- 1002 Node* PhaseIdealLoop::exact_limit( IdealLoopTree *loop ) { 1003 assert(loop->_head->is_CountedLoop(), ""); 1004 CountedLoopNode *cl = loop->_head->as_CountedLoop(); 1005 assert(cl->is_valid_counted_loop(), ""); 1006 1007 if (ABS(cl->stride_con()) == 1 || 1008 cl->limit()->Opcode() == Op_LoopLimit) { 1009 // Old code has exact limit (it could be incorrect in case of int overflow). 1010 // Loop limit is exact with stride == 1. And loop may already have exact limit. 1011 return cl->limit(); 1012 } 1013 Node *limit = NULL; 1014 #ifdef ASSERT 1015 BoolTest::mask bt = cl->loopexit()->test_trip(); 1016 assert(bt == BoolTest::lt || bt == BoolTest::gt, "canonical test is expected"); 1017 #endif 1018 if (cl->has_exact_trip_count()) { 1019 // Simple case: loop has constant boundaries. 1020 // Use jlongs to avoid integer overflow. 1021 int stride_con = cl->stride_con(); 1022 jlong init_con = cl->init_trip()->get_int(); 1023 jlong limit_con = cl->limit()->get_int(); 1024 julong trip_cnt = cl->trip_count(); 1025 jlong final_con = init_con + trip_cnt*stride_con; 1026 int final_int = (int)final_con; 1027 // The final value should be in integer range since the loop 1028 // is counted and the limit was checked for overflow. 1029 assert(final_con == (jlong)final_int, "final value should be integer"); 1030 limit = _igvn.intcon(final_int); 1031 } else { 1032 // Create new LoopLimit node to get exact limit (final iv value). 1033 limit = new LoopLimitNode(C, cl->init_trip(), cl->limit(), cl->stride()); 1034 register_new_node(limit, cl->in(LoopNode::EntryControl)); 1035 } 1036 assert(limit != NULL, "sanity"); 1037 return limit; 1038 } 1039 1040 //------------------------------Ideal------------------------------------------ 1041 // Return a node which is more "ideal" than the current node. 1042 // Attempt to convert into a counted-loop. 1043 Node *LoopNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1044 if (!can_be_counted_loop(phase) && !is_OuterStripMinedLoop()) { 1045 phase->C->set_major_progress(); 1046 } 1047 return RegionNode::Ideal(phase, can_reshape); 1048 } 1049 1050 #ifdef ASSERT 1051 void LoopNode::verify_strip_mined(int expect_skeleton) const { 1052 const OuterStripMinedLoopNode* outer = NULL; 1053 const CountedLoopNode* inner = NULL; 1054 if (is_strip_mined()) { 1055 if (!is_valid_counted_loop()) { 1056 return; // Skip malformed counted loop 1057 } 1058 assert(is_CountedLoop(), "no Loop should be marked strip mined"); 1059 inner = as_CountedLoop(); 1060 outer = inner->in(LoopNode::EntryControl)->as_OuterStripMinedLoop(); 1061 } else if (is_OuterStripMinedLoop()) { 1062 outer = this->as_OuterStripMinedLoop(); 1063 inner = outer->unique_ctrl_out()->as_CountedLoop(); 1064 assert(inner->is_valid_counted_loop() && inner->is_strip_mined(), "OuterStripMinedLoop should have been removed"); 1065 assert(!is_strip_mined(), "outer loop shouldn't be marked strip mined"); 1066 } 1067 if (inner != NULL || outer != NULL) { 1068 assert(inner != NULL && outer != NULL, "missing loop in strip mined nest"); 1069 Node* outer_tail = outer->in(LoopNode::LoopBackControl); 1070 Node* outer_le = outer_tail->in(0); 1071 assert(outer_le->Opcode() == Op_OuterStripMinedLoopEnd, "tail of outer loop should be an If"); 1072 Node* sfpt = outer_le->in(0); 1073 assert(sfpt->Opcode() == Op_SafePoint, "where's the safepoint?"); 1074 Node* inner_out = sfpt->in(0); 1075 if (inner_out->outcnt() != 1) { 1076 ResourceMark rm; 1077 Unique_Node_List wq; 1078 1079 for (DUIterator_Fast imax, i = inner_out->fast_outs(imax); i < imax; i++) { 1080 Node* u = inner_out->fast_out(i); 1081 if (u == sfpt) { 1082 continue; 1083 } 1084 wq.clear(); 1085 wq.push(u); 1086 bool found_sfpt = false; 1087 for (uint next = 0; next < wq.size() && !found_sfpt; next++) { 1088 Node* n = wq.at(next); 1089 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax && !found_sfpt; i++) { 1090 Node* u = n->fast_out(i); 1091 if (u == sfpt) { 1092 found_sfpt = true; 1093 } 1094 if (!u->is_CFG()) { 1095 wq.push(u); 1096 } 1097 } 1098 } 1099 assert(found_sfpt, "no node in loop that's not input to safepoint"); 1100 } 1101 } 1102 1103 CountedLoopEndNode* cle = inner_out->in(0)->as_CountedLoopEnd(); 1104 assert(cle == inner->loopexit_or_null(), "mismatch"); 1105 bool has_skeleton = outer_le->in(1)->bottom_type()->singleton() && outer_le->in(1)->bottom_type()->is_int()->get_con() == 0; 1106 if (has_skeleton) { 1107 assert(expect_skeleton == 1 || expect_skeleton == -1, "unexpected skeleton node"); 1108 assert(outer->outcnt() == 2, "only phis"); 1109 } else { 1110 assert(expect_skeleton == 0 || expect_skeleton == -1, "no skeleton node?"); 1111 uint phis = 0; 1112 for (DUIterator_Fast imax, i = inner->fast_outs(imax); i < imax; i++) { 1113 Node* u = inner->fast_out(i); 1114 if (u->is_Phi()) { 1115 phis++; 1116 } 1117 } 1118 for (DUIterator_Fast imax, i = outer->fast_outs(imax); i < imax; i++) { 1119 Node* u = outer->fast_out(i); 1120 assert(u == outer || u == inner || u->is_Phi(), "nothing between inner and outer loop"); 1121 } 1122 uint stores = 0; 1123 for (DUIterator_Fast imax, i = inner_out->fast_outs(imax); i < imax; i++) { 1124 Node* u = inner_out->fast_out(i); 1125 if (u->is_Store()) { 1126 stores++; 1127 } 1128 } 1129 assert(outer->outcnt() >= phis + 2 && outer->outcnt() <= phis + 2 + stores + 1, "only phis"); 1130 } 1131 assert(sfpt->outcnt() == 1, "no data node"); 1132 assert(outer_tail->outcnt() == 1 || !has_skeleton, "no data node"); 1133 } 1134 } 1135 #endif 1136 1137 //============================================================================= 1138 //------------------------------Ideal------------------------------------------ 1139 // Return a node which is more "ideal" than the current node. 1140 // Attempt to convert into a counted-loop. 1141 Node *CountedLoopNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1142 return RegionNode::Ideal(phase, can_reshape); 1143 } 1144 1145 //------------------------------dump_spec-------------------------------------- 1146 // Dump special per-node info 1147 #ifndef PRODUCT 1148 void CountedLoopNode::dump_spec(outputStream *st) const { 1149 LoopNode::dump_spec(st); 1150 if (stride_is_con()) { 1151 st->print("stride: %d ",stride_con()); 1152 } 1153 if (is_pre_loop ()) st->print("pre of N%d" , _main_idx); 1154 if (is_main_loop()) st->print("main of N%d", _idx); 1155 if (is_post_loop()) st->print("post of N%d", _main_idx); 1156 if (is_strip_mined()) st->print(" strip mined"); 1157 } 1158 #endif 1159 1160 //============================================================================= 1161 int CountedLoopEndNode::stride_con() const { 1162 return stride()->bottom_type()->is_int()->get_con(); 1163 } 1164 1165 //============================================================================= 1166 //------------------------------Value----------------------------------------- 1167 const Type* LoopLimitNode::Value(PhaseGVN* phase) const { 1168 const Type* init_t = phase->type(in(Init)); 1169 const Type* limit_t = phase->type(in(Limit)); 1170 const Type* stride_t = phase->type(in(Stride)); 1171 // Either input is TOP ==> the result is TOP 1172 if (init_t == Type::TOP) return Type::TOP; 1173 if (limit_t == Type::TOP) return Type::TOP; 1174 if (stride_t == Type::TOP) return Type::TOP; 1175 1176 int stride_con = stride_t->is_int()->get_con(); 1177 if (stride_con == 1) 1178 return NULL; // Identity 1179 1180 if (init_t->is_int()->is_con() && limit_t->is_int()->is_con()) { 1181 // Use jlongs to avoid integer overflow. 1182 jlong init_con = init_t->is_int()->get_con(); 1183 jlong limit_con = limit_t->is_int()->get_con(); 1184 int stride_m = stride_con - (stride_con > 0 ? 1 : -1); 1185 jlong trip_count = (limit_con - init_con + stride_m)/stride_con; 1186 jlong final_con = init_con + stride_con*trip_count; 1187 int final_int = (int)final_con; 1188 // The final value should be in integer range since the loop 1189 // is counted and the limit was checked for overflow. 1190 assert(final_con == (jlong)final_int, "final value should be integer"); 1191 return TypeInt::make(final_int); 1192 } 1193 1194 return bottom_type(); // TypeInt::INT 1195 } 1196 1197 //------------------------------Ideal------------------------------------------ 1198 // Return a node which is more "ideal" than the current node. 1199 Node *LoopLimitNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1200 if (phase->type(in(Init)) == Type::TOP || 1201 phase->type(in(Limit)) == Type::TOP || 1202 phase->type(in(Stride)) == Type::TOP) 1203 return NULL; // Dead 1204 1205 int stride_con = phase->type(in(Stride))->is_int()->get_con(); 1206 if (stride_con == 1) 1207 return NULL; // Identity 1208 1209 if (in(Init)->is_Con() && in(Limit)->is_Con()) 1210 return NULL; // Value 1211 1212 // Delay following optimizations until all loop optimizations 1213 // done to keep Ideal graph simple. 1214 if (!can_reshape || phase->C->major_progress()) 1215 return NULL; 1216 1217 const TypeInt* init_t = phase->type(in(Init) )->is_int(); 1218 const TypeInt* limit_t = phase->type(in(Limit))->is_int(); 1219 int stride_p; 1220 jlong lim, ini; 1221 julong max; 1222 if (stride_con > 0) { 1223 stride_p = stride_con; 1224 lim = limit_t->_hi; 1225 ini = init_t->_lo; 1226 max = (julong)max_jint; 1227 } else { 1228 stride_p = -stride_con; 1229 lim = init_t->_hi; 1230 ini = limit_t->_lo; 1231 max = (julong)min_jint; 1232 } 1233 julong range = lim - ini + stride_p; 1234 if (range <= max) { 1235 // Convert to integer expression if it is not overflow. 1236 Node* stride_m = phase->intcon(stride_con - (stride_con > 0 ? 1 : -1)); 1237 Node *range = phase->transform(new SubINode(in(Limit), in(Init))); 1238 Node *bias = phase->transform(new AddINode(range, stride_m)); 1239 Node *trip = phase->transform(new DivINode(0, bias, in(Stride))); 1240 Node *span = phase->transform(new MulINode(trip, in(Stride))); 1241 return new AddINode(span, in(Init)); // exact limit 1242 } 1243 1244 if (is_power_of_2(stride_p) || // divisor is 2^n 1245 !Matcher::has_match_rule(Op_LoopLimit)) { // or no specialized Mach node? 1246 // Convert to long expression to avoid integer overflow 1247 // and let igvn optimizer convert this division. 1248 // 1249 Node* init = phase->transform( new ConvI2LNode(in(Init))); 1250 Node* limit = phase->transform( new ConvI2LNode(in(Limit))); 1251 Node* stride = phase->longcon(stride_con); 1252 Node* stride_m = phase->longcon(stride_con - (stride_con > 0 ? 1 : -1)); 1253 1254 Node *range = phase->transform(new SubLNode(limit, init)); 1255 Node *bias = phase->transform(new AddLNode(range, stride_m)); 1256 Node *span; 1257 if (stride_con > 0 && is_power_of_2(stride_p)) { 1258 // bias >= 0 if stride >0, so if stride is 2^n we can use &(-stride) 1259 // and avoid generating rounding for division. Zero trip guard should 1260 // guarantee that init < limit but sometimes the guard is missing and 1261 // we can get situation when init > limit. Note, for the empty loop 1262 // optimization zero trip guard is generated explicitly which leaves 1263 // only RCE predicate where exact limit is used and the predicate 1264 // will simply fail forcing recompilation. 1265 Node* neg_stride = phase->longcon(-stride_con); 1266 span = phase->transform(new AndLNode(bias, neg_stride)); 1267 } else { 1268 Node *trip = phase->transform(new DivLNode(0, bias, stride)); 1269 span = phase->transform(new MulLNode(trip, stride)); 1270 } 1271 // Convert back to int 1272 Node *span_int = phase->transform(new ConvL2INode(span)); 1273 return new AddINode(span_int, in(Init)); // exact limit 1274 } 1275 1276 return NULL; // No progress 1277 } 1278 1279 //------------------------------Identity--------------------------------------- 1280 // If stride == 1 return limit node. 1281 Node* LoopLimitNode::Identity(PhaseGVN* phase) { 1282 int stride_con = phase->type(in(Stride))->is_int()->get_con(); 1283 if (stride_con == 1 || stride_con == -1) 1284 return in(Limit); 1285 return this; 1286 } 1287 1288 //============================================================================= 1289 //----------------------match_incr_with_optional_truncation-------------------- 1290 // Match increment with optional truncation: 1291 // CHAR: (i+1)&0x7fff, BYTE: ((i+1)<<8)>>8, or SHORT: ((i+1)<<16)>>16 1292 // Return NULL for failure. Success returns the increment node. 1293 Node* CountedLoopNode::match_incr_with_optional_truncation( 1294 Node* expr, Node** trunc1, Node** trunc2, const TypeInt** trunc_type) { 1295 // Quick cutouts: 1296 if (expr == NULL || expr->req() != 3) return NULL; 1297 1298 Node *t1 = NULL; 1299 Node *t2 = NULL; 1300 const TypeInt* trunc_t = TypeInt::INT; 1301 Node* n1 = expr; 1302 int n1op = n1->Opcode(); 1303 1304 // Try to strip (n1 & M) or (n1 << N >> N) from n1. 1305 if (n1op == Op_AndI && 1306 n1->in(2)->is_Con() && 1307 n1->in(2)->bottom_type()->is_int()->get_con() == 0x7fff) { 1308 // %%% This check should match any mask of 2**K-1. 1309 t1 = n1; 1310 n1 = t1->in(1); 1311 n1op = n1->Opcode(); 1312 trunc_t = TypeInt::CHAR; 1313 } else if (n1op == Op_RShiftI && 1314 n1->in(1) != NULL && 1315 n1->in(1)->Opcode() == Op_LShiftI && 1316 n1->in(2) == n1->in(1)->in(2) && 1317 n1->in(2)->is_Con()) { 1318 jint shift = n1->in(2)->bottom_type()->is_int()->get_con(); 1319 // %%% This check should match any shift in [1..31]. 1320 if (shift == 16 || shift == 8) { 1321 t1 = n1; 1322 t2 = t1->in(1); 1323 n1 = t2->in(1); 1324 n1op = n1->Opcode(); 1325 if (shift == 16) { 1326 trunc_t = TypeInt::SHORT; 1327 } else if (shift == 8) { 1328 trunc_t = TypeInt::BYTE; 1329 } 1330 } 1331 } 1332 1333 // If (maybe after stripping) it is an AddI, we won: 1334 if (n1op == Op_AddI) { 1335 *trunc1 = t1; 1336 *trunc2 = t2; 1337 *trunc_type = trunc_t; 1338 return n1; 1339 } 1340 1341 // failed 1342 return NULL; 1343 } 1344 1345 LoopNode* CountedLoopNode::skip_strip_mined(int expect_skeleton) { 1346 if (is_strip_mined() && is_valid_counted_loop()) { 1347 verify_strip_mined(expect_skeleton); 1348 return in(EntryControl)->as_Loop(); 1349 } 1350 return this; 1351 } 1352 1353 OuterStripMinedLoopNode* CountedLoopNode::outer_loop() const { 1354 assert(is_strip_mined(), "not a strip mined loop"); 1355 Node* c = in(EntryControl); 1356 if (c == NULL || c->is_top() || !c->is_OuterStripMinedLoop()) { 1357 return NULL; 1358 } 1359 return c->as_OuterStripMinedLoop(); 1360 } 1361 1362 IfTrueNode* OuterStripMinedLoopNode::outer_loop_tail() const { 1363 Node* c = in(LoopBackControl); 1364 if (c == NULL || c->is_top()) { 1365 return NULL; 1366 } 1367 return c->as_IfTrue(); 1368 } 1369 1370 IfTrueNode* CountedLoopNode::outer_loop_tail() const { 1371 LoopNode* l = outer_loop(); 1372 if (l == NULL) { 1373 return NULL; 1374 } 1375 return l->outer_loop_tail(); 1376 } 1377 1378 OuterStripMinedLoopEndNode* OuterStripMinedLoopNode::outer_loop_end() const { 1379 IfTrueNode* proj = outer_loop_tail(); 1380 if (proj == NULL) { 1381 return NULL; 1382 } 1383 Node* c = proj->in(0); 1384 if (c == NULL || c->is_top() || c->outcnt() != 2) { 1385 return NULL; 1386 } 1387 return c->as_OuterStripMinedLoopEnd(); 1388 } 1389 1390 OuterStripMinedLoopEndNode* CountedLoopNode::outer_loop_end() const { 1391 LoopNode* l = outer_loop(); 1392 if (l == NULL) { 1393 return NULL; 1394 } 1395 return l->outer_loop_end(); 1396 } 1397 1398 IfFalseNode* OuterStripMinedLoopNode::outer_loop_exit() const { 1399 IfNode* le = outer_loop_end(); 1400 if (le == NULL) { 1401 return NULL; 1402 } 1403 Node* c = le->proj_out_or_null(false); 1404 if (c == NULL) { 1405 return NULL; 1406 } 1407 return c->as_IfFalse(); 1408 } 1409 1410 IfFalseNode* CountedLoopNode::outer_loop_exit() const { 1411 LoopNode* l = outer_loop(); 1412 if (l == NULL) { 1413 return NULL; 1414 } 1415 return l->outer_loop_exit(); 1416 } 1417 1418 SafePointNode* OuterStripMinedLoopNode::outer_safepoint() const { 1419 IfNode* le = outer_loop_end(); 1420 if (le == NULL) { 1421 return NULL; 1422 } 1423 Node* c = le->in(0); 1424 if (c == NULL || c->is_top()) { 1425 return NULL; 1426 } 1427 assert(c->Opcode() == Op_SafePoint, "broken outer loop"); 1428 return c->as_SafePoint(); 1429 } 1430 1431 SafePointNode* CountedLoopNode::outer_safepoint() const { 1432 LoopNode* l = outer_loop(); 1433 if (l == NULL) { 1434 return NULL; 1435 } 1436 return l->outer_safepoint(); 1437 } 1438 1439 Node* CountedLoopNode::skip_predicates_from_entry(Node* ctrl) { 1440 while (ctrl != NULL && ctrl->is_Proj() && ctrl->in(0)->is_If() && 1441 ctrl->in(0)->as_If()->proj_out(1-ctrl->as_Proj()->_con)->outcnt() == 1 && 1442 ctrl->in(0)->as_If()->proj_out(1-ctrl->as_Proj()->_con)->unique_out()->Opcode() == Op_Halt) { 1443 ctrl = ctrl->in(0)->in(0); 1444 } 1445 1446 return ctrl; 1447 } 1448 1449 Node* CountedLoopNode::skip_predicates() { 1450 if (is_main_loop()) { 1451 Node* ctrl = skip_strip_mined()->in(LoopNode::EntryControl); 1452 1453 return skip_predicates_from_entry(ctrl); 1454 } 1455 return in(LoopNode::EntryControl); 1456 } 1457 1458 void OuterStripMinedLoopNode::adjust_strip_mined_loop(PhaseIterGVN* igvn) { 1459 // Look for the outer & inner strip mined loop, reduce number of 1460 // iterations of the inner loop, set exit condition of outer loop, 1461 // construct required phi nodes for outer loop. 1462 CountedLoopNode* inner_cl = unique_ctrl_out()->as_CountedLoop(); 1463 assert(inner_cl->is_strip_mined(), "inner loop should be strip mined"); 1464 Node* inner_iv_phi = inner_cl->phi(); 1465 if (inner_iv_phi == NULL) { 1466 IfNode* outer_le = outer_loop_end(); 1467 Node* iff = igvn->transform(new IfNode(outer_le->in(0), outer_le->in(1), outer_le->_prob, outer_le->_fcnt)); 1468 igvn->replace_node(outer_le, iff); 1469 inner_cl->clear_strip_mined(); 1470 return; 1471 } 1472 CountedLoopEndNode* inner_cle = inner_cl->loopexit(); 1473 1474 int stride = inner_cl->stride_con(); 1475 jlong scaled_iters_long = ((jlong)LoopStripMiningIter) * ABS(stride); 1476 int scaled_iters = (int)scaled_iters_long; 1477 int short_scaled_iters = LoopStripMiningIterShortLoop* ABS(stride); 1478 const TypeInt* inner_iv_t = igvn->type(inner_iv_phi)->is_int(); 1479 jlong iter_estimate = (jlong)inner_iv_t->_hi - (jlong)inner_iv_t->_lo; 1480 assert(iter_estimate > 0, "broken"); 1481 if ((jlong)scaled_iters != scaled_iters_long || iter_estimate <= short_scaled_iters) { 1482 // Remove outer loop and safepoint (too few iterations) 1483 Node* outer_sfpt = outer_safepoint(); 1484 Node* outer_out = outer_loop_exit(); 1485 igvn->replace_node(outer_out, outer_sfpt->in(0)); 1486 igvn->replace_input_of(outer_sfpt, 0, igvn->C->top()); 1487 inner_cl->clear_strip_mined(); 1488 return; 1489 } 1490 if (iter_estimate <= scaled_iters_long) { 1491 // We would only go through one iteration of 1492 // the outer loop: drop the outer loop but 1493 // keep the safepoint so we don't run for 1494 // too long without a safepoint 1495 IfNode* outer_le = outer_loop_end(); 1496 Node* iff = igvn->transform(new IfNode(outer_le->in(0), outer_le->in(1), outer_le->_prob, outer_le->_fcnt)); 1497 igvn->replace_node(outer_le, iff); 1498 inner_cl->clear_strip_mined(); 1499 return; 1500 } 1501 1502 Node* cle_tail = inner_cle->proj_out(true); 1503 ResourceMark rm; 1504 Node_List old_new; 1505 if (cle_tail->outcnt() > 1) { 1506 // Look for nodes on backedge of inner loop and clone them 1507 Unique_Node_List backedge_nodes; 1508 for (DUIterator_Fast imax, i = cle_tail->fast_outs(imax); i < imax; i++) { 1509 Node* u = cle_tail->fast_out(i); 1510 if (u != inner_cl) { 1511 assert(!u->is_CFG(), "control flow on the backedge?"); 1512 backedge_nodes.push(u); 1513 } 1514 } 1515 uint last = igvn->C->unique(); 1516 for (uint next = 0; next < backedge_nodes.size(); next++) { 1517 Node* n = backedge_nodes.at(next); 1518 old_new.map(n->_idx, n->clone()); 1519 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) { 1520 Node* u = n->fast_out(i); 1521 assert(!u->is_CFG(), "broken"); 1522 if (u->_idx >= last) { 1523 continue; 1524 } 1525 if (!u->is_Phi()) { 1526 backedge_nodes.push(u); 1527 } else { 1528 assert(u->in(0) == inner_cl, "strange phi on the backedge"); 1529 } 1530 } 1531 } 1532 // Put the clones on the outer loop backedge 1533 Node* le_tail = outer_loop_tail(); 1534 for (uint next = 0; next < backedge_nodes.size(); next++) { 1535 Node *n = old_new[backedge_nodes.at(next)->_idx]; 1536 for (uint i = 1; i < n->req(); i++) { 1537 if (n->in(i) != NULL && old_new[n->in(i)->_idx] != NULL) { 1538 n->set_req(i, old_new[n->in(i)->_idx]); 1539 } 1540 } 1541 if (n->in(0) != NULL && n->in(0) == cle_tail) { 1542 n->set_req(0, le_tail); 1543 } 1544 igvn->register_new_node_with_optimizer(n); 1545 } 1546 } 1547 1548 Node* iv_phi = NULL; 1549 // Make a clone of each phi in the inner loop 1550 // for the outer loop 1551 for (uint i = 0; i < inner_cl->outcnt(); i++) { 1552 Node* u = inner_cl->raw_out(i); 1553 if (u->is_Phi()) { 1554 assert(u->in(0) == inner_cl, "inconsistent"); 1555 Node* phi = u->clone(); 1556 phi->set_req(0, this); 1557 Node* be = old_new[phi->in(LoopNode::LoopBackControl)->_idx]; 1558 if (be != NULL) { 1559 phi->set_req(LoopNode::LoopBackControl, be); 1560 } 1561 phi = igvn->transform(phi); 1562 igvn->replace_input_of(u, LoopNode::EntryControl, phi); 1563 if (u == inner_iv_phi) { 1564 iv_phi = phi; 1565 } 1566 } 1567 } 1568 Node* cle_out = inner_cle->proj_out(false); 1569 if (cle_out->outcnt() > 1) { 1570 // Look for chains of stores that were sunk 1571 // out of the inner loop and are in the outer loop 1572 for (DUIterator_Fast imax, i = cle_out->fast_outs(imax); i < imax; i++) { 1573 Node* u = cle_out->fast_out(i); 1574 if (u->is_Store()) { 1575 Node* first = u; 1576 for(;;) { 1577 Node* next = first->in(MemNode::Memory); 1578 if (!next->is_Store() || next->in(0) != cle_out) { 1579 break; 1580 } 1581 first = next; 1582 } 1583 Node* last = u; 1584 for(;;) { 1585 Node* next = NULL; 1586 for (DUIterator_Fast jmax, j = last->fast_outs(jmax); j < jmax; j++) { 1587 Node* uu = last->fast_out(j); 1588 if (uu->is_Store() && uu->in(0) == cle_out) { 1589 assert(next == NULL, "only one in the outer loop"); 1590 next = uu; 1591 } 1592 } 1593 if (next == NULL) { 1594 break; 1595 } 1596 last = next; 1597 } 1598 Node* phi = NULL; 1599 for (DUIterator_Fast jmax, j = fast_outs(jmax); j < jmax; j++) { 1600 Node* uu = fast_out(j); 1601 if (uu->is_Phi()) { 1602 Node* be = uu->in(LoopNode::LoopBackControl); 1603 if (be->is_Store() && old_new[be->_idx] != NULL) { 1604 assert(false, "store on the backedge + sunk stores: unsupported"); 1605 // drop outer loop 1606 IfNode* outer_le = outer_loop_end(); 1607 Node* iff = igvn->transform(new IfNode(outer_le->in(0), outer_le->in(1), outer_le->_prob, outer_le->_fcnt)); 1608 igvn->replace_node(outer_le, iff); 1609 inner_cl->clear_strip_mined(); 1610 return; 1611 } 1612 if (be == last || be == first->in(MemNode::Memory)) { 1613 assert(phi == NULL, "only one phi"); 1614 phi = uu; 1615 } 1616 } 1617 } 1618 #ifdef ASSERT 1619 for (DUIterator_Fast jmax, j = fast_outs(jmax); j < jmax; j++) { 1620 Node* uu = fast_out(j); 1621 if (uu->is_Phi() && uu->bottom_type() == Type::MEMORY) { 1622 if (uu->adr_type() == igvn->C->get_adr_type(igvn->C->get_alias_index(u->adr_type()))) { 1623 assert(phi == uu, "what's that phi?"); 1624 } else if (uu->adr_type() == TypePtr::BOTTOM) { 1625 Node* n = uu->in(LoopNode::LoopBackControl); 1626 uint limit = igvn->C->live_nodes(); 1627 uint i = 0; 1628 while (n != uu) { 1629 i++; 1630 assert(i < limit, "infinite loop"); 1631 if (n->is_Proj()) { 1632 n = n->in(0); 1633 } else if (n->is_SafePoint() || n->is_MemBar()) { 1634 n = n->in(TypeFunc::Memory); 1635 } else if (n->is_Phi()) { 1636 n = n->in(1); 1637 } else if (n->is_MergeMem()) { 1638 n = n->as_MergeMem()->memory_at(igvn->C->get_alias_index(u->adr_type())); 1639 } else if (n->is_Store() || n->is_LoadStore() || n->is_ClearArray()) { 1640 n = n->in(MemNode::Memory); 1641 } else { 1642 n->dump(); 1643 ShouldNotReachHere(); 1644 } 1645 } 1646 } 1647 } 1648 } 1649 #endif 1650 if (phi == NULL) { 1651 // If the an entire chains was sunk, the 1652 // inner loop has no phi for that memory 1653 // slice, create one for the outer loop 1654 phi = PhiNode::make(this, first->in(MemNode::Memory), Type::MEMORY, 1655 igvn->C->get_adr_type(igvn->C->get_alias_index(u->adr_type()))); 1656 phi->set_req(LoopNode::LoopBackControl, last); 1657 phi = igvn->transform(phi); 1658 igvn->replace_input_of(first, MemNode::Memory, phi); 1659 } else { 1660 // Or fix the outer loop fix to include 1661 // that chain of stores. 1662 Node* be = phi->in(LoopNode::LoopBackControl); 1663 assert(!(be->is_Store() && old_new[be->_idx] != NULL), "store on the backedge + sunk stores: unsupported"); 1664 if (be == first->in(MemNode::Memory)) { 1665 if (be == phi->in(LoopNode::LoopBackControl)) { 1666 igvn->replace_input_of(phi, LoopNode::LoopBackControl, last); 1667 } else { 1668 igvn->replace_input_of(be, MemNode::Memory, last); 1669 } 1670 } else { 1671 #ifdef ASSERT 1672 if (be == phi->in(LoopNode::LoopBackControl)) { 1673 assert(phi->in(LoopNode::LoopBackControl) == last, ""); 1674 } else { 1675 assert(be->in(MemNode::Memory) == last, ""); 1676 } 1677 #endif 1678 } 1679 } 1680 } 1681 } 1682 } 1683 1684 if (iv_phi != NULL) { 1685 // Now adjust the inner loop's exit condition 1686 Node* limit = inner_cl->limit(); 1687 // If limit < init for stride > 0 (or limit > init for stride 0), 1688 // the loop body is run only once. Given limit - init (init - limit resp.) 1689 // would be negative, the unsigned comparison below would cause 1690 // the loop body to be run for LoopStripMiningIter. 1691 Node* max = NULL; 1692 if (stride > 0) { 1693 max = MaxNode::max_diff_with_zero(limit, iv_phi, TypeInt::INT, *igvn); 1694 } else { 1695 max = MaxNode::max_diff_with_zero(iv_phi, limit, TypeInt::INT, *igvn); 1696 } 1697 // sub is positive and can be larger than the max signed int 1698 // value. Use an unsigned min. 1699 Node* const_iters = igvn->intcon(scaled_iters); 1700 Node* min = MaxNode::unsigned_min(max, const_iters, TypeInt::make(0, scaled_iters, Type::WidenMin), *igvn); 1701 // min is the number of iterations for the next inner loop execution: 1702 // unsigned_min(max(limit - iv_phi, 0), scaled_iters) if stride > 0 1703 // unsigned_min(max(iv_phi - limit, 0), scaled_iters) if stride < 0 1704 1705 Node* new_limit = NULL; 1706 if (stride > 0) { 1707 new_limit = igvn->transform(new AddINode(min, iv_phi)); 1708 } else { 1709 new_limit = igvn->transform(new SubINode(iv_phi, min)); 1710 } 1711 Node* inner_cmp = inner_cle->cmp_node(); 1712 Node* inner_bol = inner_cle->in(CountedLoopEndNode::TestValue); 1713 Node* outer_bol = inner_bol; 1714 // cmp node for inner loop may be shared 1715 inner_cmp = inner_cmp->clone(); 1716 inner_cmp->set_req(2, new_limit); 1717 inner_bol = inner_bol->clone(); 1718 inner_bol->set_req(1, igvn->transform(inner_cmp)); 1719 igvn->replace_input_of(inner_cle, CountedLoopEndNode::TestValue, igvn->transform(inner_bol)); 1720 // Set the outer loop's exit condition too 1721 igvn->replace_input_of(outer_loop_end(), 1, outer_bol); 1722 } else { 1723 assert(false, "should be able to adjust outer loop"); 1724 IfNode* outer_le = outer_loop_end(); 1725 Node* iff = igvn->transform(new IfNode(outer_le->in(0), outer_le->in(1), outer_le->_prob, outer_le->_fcnt)); 1726 igvn->replace_node(outer_le, iff); 1727 inner_cl->clear_strip_mined(); 1728 } 1729 } 1730 1731 const Type* OuterStripMinedLoopEndNode::Value(PhaseGVN* phase) const { 1732 if (!in(0)) return Type::TOP; 1733 if (phase->type(in(0)) == Type::TOP) 1734 return Type::TOP; 1735 1736 return TypeTuple::IFBOTH; 1737 } 1738 1739 Node *OuterStripMinedLoopEndNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1740 if (remove_dead_region(phase, can_reshape)) return this; 1741 1742 return NULL; 1743 } 1744 1745 //------------------------------filtered_type-------------------------------- 1746 // Return a type based on condition control flow 1747 // A successful return will be a type that is restricted due 1748 // to a series of dominating if-tests, such as: 1749 // if (i < 10) { 1750 // if (i > 0) { 1751 // here: "i" type is [1..10) 1752 // } 1753 // } 1754 // or a control flow merge 1755 // if (i < 10) { 1756 // do { 1757 // phi( , ) -- at top of loop type is [min_int..10) 1758 // i = ? 1759 // } while ( i < 10) 1760 // 1761 const TypeInt* PhaseIdealLoop::filtered_type( Node *n, Node* n_ctrl) { 1762 assert(n && n->bottom_type()->is_int(), "must be int"); 1763 const TypeInt* filtered_t = NULL; 1764 if (!n->is_Phi()) { 1765 assert(n_ctrl != NULL || n_ctrl == C->top(), "valid control"); 1766 filtered_t = filtered_type_from_dominators(n, n_ctrl); 1767 1768 } else { 1769 Node* phi = n->as_Phi(); 1770 Node* region = phi->in(0); 1771 assert(n_ctrl == NULL || n_ctrl == region, "ctrl parameter must be region"); 1772 if (region && region != C->top()) { 1773 for (uint i = 1; i < phi->req(); i++) { 1774 Node* val = phi->in(i); 1775 Node* use_c = region->in(i); 1776 const TypeInt* val_t = filtered_type_from_dominators(val, use_c); 1777 if (val_t != NULL) { 1778 if (filtered_t == NULL) { 1779 filtered_t = val_t; 1780 } else { 1781 filtered_t = filtered_t->meet(val_t)->is_int(); 1782 } 1783 } 1784 } 1785 } 1786 } 1787 const TypeInt* n_t = _igvn.type(n)->is_int(); 1788 if (filtered_t != NULL) { 1789 n_t = n_t->join(filtered_t)->is_int(); 1790 } 1791 return n_t; 1792 } 1793 1794 1795 //------------------------------filtered_type_from_dominators-------------------------------- 1796 // Return a possibly more restrictive type for val based on condition control flow of dominators 1797 const TypeInt* PhaseIdealLoop::filtered_type_from_dominators( Node* val, Node *use_ctrl) { 1798 if (val->is_Con()) { 1799 return val->bottom_type()->is_int(); 1800 } 1801 uint if_limit = 10; // Max number of dominating if's visited 1802 const TypeInt* rtn_t = NULL; 1803 1804 if (use_ctrl && use_ctrl != C->top()) { 1805 Node* val_ctrl = get_ctrl(val); 1806 uint val_dom_depth = dom_depth(val_ctrl); 1807 Node* pred = use_ctrl; 1808 uint if_cnt = 0; 1809 while (if_cnt < if_limit) { 1810 if ((pred->Opcode() == Op_IfTrue || pred->Opcode() == Op_IfFalse)) { 1811 if_cnt++; 1812 const TypeInt* if_t = IfNode::filtered_int_type(&_igvn, val, pred); 1813 if (if_t != NULL) { 1814 if (rtn_t == NULL) { 1815 rtn_t = if_t; 1816 } else { 1817 rtn_t = rtn_t->join(if_t)->is_int(); 1818 } 1819 } 1820 } 1821 pred = idom(pred); 1822 if (pred == NULL || pred == C->top()) { 1823 break; 1824 } 1825 // Stop if going beyond definition block of val 1826 if (dom_depth(pred) < val_dom_depth) { 1827 break; 1828 } 1829 } 1830 } 1831 return rtn_t; 1832 } 1833 1834 1835 //------------------------------dump_spec-------------------------------------- 1836 // Dump special per-node info 1837 #ifndef PRODUCT 1838 void CountedLoopEndNode::dump_spec(outputStream *st) const { 1839 if( in(TestValue) != NULL && in(TestValue)->is_Bool() ) { 1840 BoolTest bt( test_trip()); // Added this for g++. 1841 1842 st->print("["); 1843 bt.dump_on(st); 1844 st->print("]"); 1845 } 1846 st->print(" "); 1847 IfNode::dump_spec(st); 1848 } 1849 #endif 1850 1851 //============================================================================= 1852 //------------------------------is_member-------------------------------------- 1853 // Is 'l' a member of 'this'? 1854 bool IdealLoopTree::is_member(const IdealLoopTree *l) const { 1855 while( l->_nest > _nest ) l = l->_parent; 1856 return l == this; 1857 } 1858 1859 //------------------------------set_nest--------------------------------------- 1860 // Set loop tree nesting depth. Accumulate _has_call bits. 1861 int IdealLoopTree::set_nest( uint depth ) { 1862 _nest = depth; 1863 int bits = _has_call; 1864 if( _child ) bits |= _child->set_nest(depth+1); 1865 if( bits ) _has_call = 1; 1866 if( _next ) bits |= _next ->set_nest(depth ); 1867 return bits; 1868 } 1869 1870 //------------------------------split_fall_in---------------------------------- 1871 // Split out multiple fall-in edges from the loop header. Move them to a 1872 // private RegionNode before the loop. This becomes the loop landing pad. 1873 void IdealLoopTree::split_fall_in( PhaseIdealLoop *phase, int fall_in_cnt ) { 1874 PhaseIterGVN &igvn = phase->_igvn; 1875 uint i; 1876 1877 // Make a new RegionNode to be the landing pad. 1878 Node *landing_pad = new RegionNode( fall_in_cnt+1 ); 1879 phase->set_loop(landing_pad,_parent); 1880 // Gather all the fall-in control paths into the landing pad 1881 uint icnt = fall_in_cnt; 1882 uint oreq = _head->req(); 1883 for( i = oreq-1; i>0; i-- ) 1884 if( !phase->is_member( this, _head->in(i) ) ) 1885 landing_pad->set_req(icnt--,_head->in(i)); 1886 1887 // Peel off PhiNode edges as well 1888 for (DUIterator_Fast jmax, j = _head->fast_outs(jmax); j < jmax; j++) { 1889 Node *oj = _head->fast_out(j); 1890 if( oj->is_Phi() ) { 1891 PhiNode* old_phi = oj->as_Phi(); 1892 assert( old_phi->region() == _head, "" ); 1893 igvn.hash_delete(old_phi); // Yank from hash before hacking edges 1894 Node *p = PhiNode::make_blank(landing_pad, old_phi); 1895 uint icnt = fall_in_cnt; 1896 for( i = oreq-1; i>0; i-- ) { 1897 if( !phase->is_member( this, _head->in(i) ) ) { 1898 p->init_req(icnt--, old_phi->in(i)); 1899 // Go ahead and clean out old edges from old phi 1900 old_phi->del_req(i); 1901 } 1902 } 1903 // Search for CSE's here, because ZKM.jar does a lot of 1904 // loop hackery and we need to be a little incremental 1905 // with the CSE to avoid O(N^2) node blow-up. 1906 Node *p2 = igvn.hash_find_insert(p); // Look for a CSE 1907 if( p2 ) { // Found CSE 1908 p->destruct(); // Recover useless new node 1909 p = p2; // Use old node 1910 } else { 1911 igvn.register_new_node_with_optimizer(p, old_phi); 1912 } 1913 // Make old Phi refer to new Phi. 1914 old_phi->add_req(p); 1915 // Check for the special case of making the old phi useless and 1916 // disappear it. In JavaGrande I have a case where this useless 1917 // Phi is the loop limit and prevents recognizing a CountedLoop 1918 // which in turn prevents removing an empty loop. 1919 Node *id_old_phi = old_phi->Identity(&igvn); 1920 if( id_old_phi != old_phi ) { // Found a simple identity? 1921 // Note that I cannot call 'replace_node' here, because 1922 // that will yank the edge from old_phi to the Region and 1923 // I'm mid-iteration over the Region's uses. 1924 for (DUIterator_Last imin, i = old_phi->last_outs(imin); i >= imin; ) { 1925 Node* use = old_phi->last_out(i); 1926 igvn.rehash_node_delayed(use); 1927 uint uses_found = 0; 1928 for (uint j = 0; j < use->len(); j++) { 1929 if (use->in(j) == old_phi) { 1930 if (j < use->req()) use->set_req (j, id_old_phi); 1931 else use->set_prec(j, id_old_phi); 1932 uses_found++; 1933 } 1934 } 1935 i -= uses_found; // we deleted 1 or more copies of this edge 1936 } 1937 } 1938 igvn._worklist.push(old_phi); 1939 } 1940 } 1941 // Finally clean out the fall-in edges from the RegionNode 1942 for( i = oreq-1; i>0; i-- ) { 1943 if( !phase->is_member( this, _head->in(i) ) ) { 1944 _head->del_req(i); 1945 } 1946 } 1947 igvn.rehash_node_delayed(_head); 1948 // Transform landing pad 1949 igvn.register_new_node_with_optimizer(landing_pad, _head); 1950 // Insert landing pad into the header 1951 _head->add_req(landing_pad); 1952 } 1953 1954 //------------------------------split_outer_loop------------------------------- 1955 // Split out the outermost loop from this shared header. 1956 void IdealLoopTree::split_outer_loop( PhaseIdealLoop *phase ) { 1957 PhaseIterGVN &igvn = phase->_igvn; 1958 1959 // Find index of outermost loop; it should also be my tail. 1960 uint outer_idx = 1; 1961 while( _head->in(outer_idx) != _tail ) outer_idx++; 1962 1963 // Make a LoopNode for the outermost loop. 1964 Node *ctl = _head->in(LoopNode::EntryControl); 1965 Node *outer = new LoopNode( ctl, _head->in(outer_idx) ); 1966 outer = igvn.register_new_node_with_optimizer(outer, _head); 1967 phase->set_created_loop_node(); 1968 1969 // Outermost loop falls into '_head' loop 1970 _head->set_req(LoopNode::EntryControl, outer); 1971 _head->del_req(outer_idx); 1972 // Split all the Phis up between '_head' loop and 'outer' loop. 1973 for (DUIterator_Fast jmax, j = _head->fast_outs(jmax); j < jmax; j++) { 1974 Node *out = _head->fast_out(j); 1975 if( out->is_Phi() ) { 1976 PhiNode *old_phi = out->as_Phi(); 1977 assert( old_phi->region() == _head, "" ); 1978 Node *phi = PhiNode::make_blank(outer, old_phi); 1979 phi->init_req(LoopNode::EntryControl, old_phi->in(LoopNode::EntryControl)); 1980 phi->init_req(LoopNode::LoopBackControl, old_phi->in(outer_idx)); 1981 phi = igvn.register_new_node_with_optimizer(phi, old_phi); 1982 // Make old Phi point to new Phi on the fall-in path 1983 igvn.replace_input_of(old_phi, LoopNode::EntryControl, phi); 1984 old_phi->del_req(outer_idx); 1985 } 1986 } 1987 1988 // Use the new loop head instead of the old shared one 1989 _head = outer; 1990 phase->set_loop(_head, this); 1991 } 1992 1993 //------------------------------fix_parent------------------------------------- 1994 static void fix_parent( IdealLoopTree *loop, IdealLoopTree *parent ) { 1995 loop->_parent = parent; 1996 if( loop->_child ) fix_parent( loop->_child, loop ); 1997 if( loop->_next ) fix_parent( loop->_next , parent ); 1998 } 1999 2000 //------------------------------estimate_path_freq----------------------------- 2001 static float estimate_path_freq( Node *n ) { 2002 // Try to extract some path frequency info 2003 IfNode *iff; 2004 for( int i = 0; i < 50; i++ ) { // Skip through a bunch of uncommon tests 2005 uint nop = n->Opcode(); 2006 if( nop == Op_SafePoint ) { // Skip any safepoint 2007 n = n->in(0); 2008 continue; 2009 } 2010 if( nop == Op_CatchProj ) { // Get count from a prior call 2011 // Assume call does not always throw exceptions: means the call-site 2012 // count is also the frequency of the fall-through path. 2013 assert( n->is_CatchProj(), "" ); 2014 if( ((CatchProjNode*)n)->_con != CatchProjNode::fall_through_index ) 2015 return 0.0f; // Assume call exception path is rare 2016 Node *call = n->in(0)->in(0)->in(0); 2017 assert( call->is_Call(), "expect a call here" ); 2018 const JVMState *jvms = ((CallNode*)call)->jvms(); 2019 ciMethodData* methodData = jvms->method()->method_data(); 2020 if (!methodData->is_mature()) return 0.0f; // No call-site data 2021 ciProfileData* data = methodData->bci_to_data(jvms->bci()); 2022 if ((data == NULL) || !data->is_CounterData()) { 2023 // no call profile available, try call's control input 2024 n = n->in(0); 2025 continue; 2026 } 2027 return data->as_CounterData()->count()/FreqCountInvocations; 2028 } 2029 // See if there's a gating IF test 2030 Node *n_c = n->in(0); 2031 if( !n_c->is_If() ) break; // No estimate available 2032 iff = n_c->as_If(); 2033 if( iff->_fcnt != COUNT_UNKNOWN ) // Have a valid count? 2034 // Compute how much count comes on this path 2035 return ((nop == Op_IfTrue) ? iff->_prob : 1.0f - iff->_prob) * iff->_fcnt; 2036 // Have no count info. Skip dull uncommon-trap like branches. 2037 if( (nop == Op_IfTrue && iff->_prob < PROB_LIKELY_MAG(5)) || 2038 (nop == Op_IfFalse && iff->_prob > PROB_UNLIKELY_MAG(5)) ) 2039 break; 2040 // Skip through never-taken branch; look for a real loop exit. 2041 n = iff->in(0); 2042 } 2043 return 0.0f; // No estimate available 2044 } 2045 2046 //------------------------------merge_many_backedges--------------------------- 2047 // Merge all the backedges from the shared header into a private Region. 2048 // Feed that region as the one backedge to this loop. 2049 void IdealLoopTree::merge_many_backedges( PhaseIdealLoop *phase ) { 2050 uint i; 2051 2052 // Scan for the top 2 hottest backedges 2053 float hotcnt = 0.0f; 2054 float warmcnt = 0.0f; 2055 uint hot_idx = 0; 2056 // Loop starts at 2 because slot 1 is the fall-in path 2057 for( i = 2; i < _head->req(); i++ ) { 2058 float cnt = estimate_path_freq(_head->in(i)); 2059 if( cnt > hotcnt ) { // Grab hottest path 2060 warmcnt = hotcnt; 2061 hotcnt = cnt; 2062 hot_idx = i; 2063 } else if( cnt > warmcnt ) { // And 2nd hottest path 2064 warmcnt = cnt; 2065 } 2066 } 2067 2068 // See if the hottest backedge is worthy of being an inner loop 2069 // by being much hotter than the next hottest backedge. 2070 if( hotcnt <= 0.0001 || 2071 hotcnt < 2.0*warmcnt ) hot_idx = 0;// No hot backedge 2072 2073 // Peel out the backedges into a private merge point; peel 2074 // them all except optionally hot_idx. 2075 PhaseIterGVN &igvn = phase->_igvn; 2076 2077 Node *hot_tail = NULL; 2078 // Make a Region for the merge point 2079 Node *r = new RegionNode(1); 2080 for( i = 2; i < _head->req(); i++ ) { 2081 if( i != hot_idx ) 2082 r->add_req( _head->in(i) ); 2083 else hot_tail = _head->in(i); 2084 } 2085 igvn.register_new_node_with_optimizer(r, _head); 2086 // Plug region into end of loop _head, followed by hot_tail 2087 while( _head->req() > 3 ) _head->del_req( _head->req()-1 ); 2088 igvn.replace_input_of(_head, 2, r); 2089 if( hot_idx ) _head->add_req(hot_tail); 2090 2091 // Split all the Phis up between '_head' loop and the Region 'r' 2092 for (DUIterator_Fast jmax, j = _head->fast_outs(jmax); j < jmax; j++) { 2093 Node *out = _head->fast_out(j); 2094 if( out->is_Phi() ) { 2095 PhiNode* n = out->as_Phi(); 2096 igvn.hash_delete(n); // Delete from hash before hacking edges 2097 Node *hot_phi = NULL; 2098 Node *phi = new PhiNode(r, n->type(), n->adr_type()); 2099 // Check all inputs for the ones to peel out 2100 uint j = 1; 2101 for( uint i = 2; i < n->req(); i++ ) { 2102 if( i != hot_idx ) 2103 phi->set_req( j++, n->in(i) ); 2104 else hot_phi = n->in(i); 2105 } 2106 // Register the phi but do not transform until whole place transforms 2107 igvn.register_new_node_with_optimizer(phi, n); 2108 // Add the merge phi to the old Phi 2109 while( n->req() > 3 ) n->del_req( n->req()-1 ); 2110 igvn.replace_input_of(n, 2, phi); 2111 if( hot_idx ) n->add_req(hot_phi); 2112 } 2113 } 2114 2115 2116 // Insert a new IdealLoopTree inserted below me. Turn it into a clone 2117 // of self loop tree. Turn self into a loop headed by _head and with 2118 // tail being the new merge point. 2119 IdealLoopTree *ilt = new IdealLoopTree( phase, _head, _tail ); 2120 phase->set_loop(_tail,ilt); // Adjust tail 2121 _tail = r; // Self's tail is new merge point 2122 phase->set_loop(r,this); 2123 ilt->_child = _child; // New guy has my children 2124 _child = ilt; // Self has new guy as only child 2125 ilt->_parent = this; // new guy has self for parent 2126 ilt->_nest = _nest; // Same nesting depth (for now) 2127 2128 // Starting with 'ilt', look for child loop trees using the same shared 2129 // header. Flatten these out; they will no longer be loops in the end. 2130 IdealLoopTree **pilt = &_child; 2131 while( ilt ) { 2132 if( ilt->_head == _head ) { 2133 uint i; 2134 for( i = 2; i < _head->req(); i++ ) 2135 if( _head->in(i) == ilt->_tail ) 2136 break; // Still a loop 2137 if( i == _head->req() ) { // No longer a loop 2138 // Flatten ilt. Hang ilt's "_next" list from the end of 2139 // ilt's '_child' list. Move the ilt's _child up to replace ilt. 2140 IdealLoopTree **cp = &ilt->_child; 2141 while( *cp ) cp = &(*cp)->_next; // Find end of child list 2142 *cp = ilt->_next; // Hang next list at end of child list 2143 *pilt = ilt->_child; // Move child up to replace ilt 2144 ilt->_head = NULL; // Flag as a loop UNIONED into parent 2145 ilt = ilt->_child; // Repeat using new ilt 2146 continue; // do not advance over ilt->_child 2147 } 2148 assert( ilt->_tail == hot_tail, "expected to only find the hot inner loop here" ); 2149 phase->set_loop(_head,ilt); 2150 } 2151 pilt = &ilt->_child; // Advance to next 2152 ilt = *pilt; 2153 } 2154 2155 if( _child ) fix_parent( _child, this ); 2156 } 2157 2158 //------------------------------beautify_loops--------------------------------- 2159 // Split shared headers and insert loop landing pads. 2160 // Insert a LoopNode to replace the RegionNode. 2161 // Return TRUE if loop tree is structurally changed. 2162 bool IdealLoopTree::beautify_loops( PhaseIdealLoop *phase ) { 2163 bool result = false; 2164 // Cache parts in locals for easy 2165 PhaseIterGVN &igvn = phase->_igvn; 2166 2167 igvn.hash_delete(_head); // Yank from hash before hacking edges 2168 2169 // Check for multiple fall-in paths. Peel off a landing pad if need be. 2170 int fall_in_cnt = 0; 2171 for( uint i = 1; i < _head->req(); i++ ) 2172 if( !phase->is_member( this, _head->in(i) ) ) 2173 fall_in_cnt++; 2174 assert( fall_in_cnt, "at least 1 fall-in path" ); 2175 if( fall_in_cnt > 1 ) // Need a loop landing pad to merge fall-ins 2176 split_fall_in( phase, fall_in_cnt ); 2177 2178 // Swap inputs to the _head and all Phis to move the fall-in edge to 2179 // the left. 2180 fall_in_cnt = 1; 2181 while( phase->is_member( this, _head->in(fall_in_cnt) ) ) 2182 fall_in_cnt++; 2183 if( fall_in_cnt > 1 ) { 2184 // Since I am just swapping inputs I do not need to update def-use info 2185 Node *tmp = _head->in(1); 2186 igvn.rehash_node_delayed(_head); 2187 _head->set_req( 1, _head->in(fall_in_cnt) ); 2188 _head->set_req( fall_in_cnt, tmp ); 2189 // Swap also all Phis 2190 for (DUIterator_Fast imax, i = _head->fast_outs(imax); i < imax; i++) { 2191 Node* phi = _head->fast_out(i); 2192 if( phi->is_Phi() ) { 2193 igvn.rehash_node_delayed(phi); // Yank from hash before hacking edges 2194 tmp = phi->in(1); 2195 phi->set_req( 1, phi->in(fall_in_cnt) ); 2196 phi->set_req( fall_in_cnt, tmp ); 2197 } 2198 } 2199 } 2200 assert( !phase->is_member( this, _head->in(1) ), "left edge is fall-in" ); 2201 assert( phase->is_member( this, _head->in(2) ), "right edge is loop" ); 2202 2203 // If I am a shared header (multiple backedges), peel off the many 2204 // backedges into a private merge point and use the merge point as 2205 // the one true backedge. 2206 if (_head->req() > 3) { 2207 // Merge the many backedges into a single backedge but leave 2208 // the hottest backedge as separate edge for the following peel. 2209 if (!_irreducible) { 2210 merge_many_backedges( phase ); 2211 } 2212 2213 // When recursively beautify my children, split_fall_in can change 2214 // loop tree structure when I am an irreducible loop. Then the head 2215 // of my children has a req() not bigger than 3. Here we need to set 2216 // result to true to catch that case in order to tell the caller to 2217 // rebuild loop tree. See issue JDK-8244407 for details. 2218 result = true; 2219 } 2220 2221 // If I have one hot backedge, peel off myself loop. 2222 // I better be the outermost loop. 2223 if (_head->req() > 3 && !_irreducible) { 2224 split_outer_loop( phase ); 2225 result = true; 2226 2227 } else if (!_head->is_Loop() && !_irreducible) { 2228 // Make a new LoopNode to replace the old loop head 2229 Node *l = new LoopNode( _head->in(1), _head->in(2) ); 2230 l = igvn.register_new_node_with_optimizer(l, _head); 2231 phase->set_created_loop_node(); 2232 // Go ahead and replace _head 2233 phase->_igvn.replace_node( _head, l ); 2234 _head = l; 2235 phase->set_loop(_head, this); 2236 } 2237 2238 // Now recursively beautify nested loops 2239 if( _child ) result |= _child->beautify_loops( phase ); 2240 if( _next ) result |= _next ->beautify_loops( phase ); 2241 return result; 2242 } 2243 2244 //------------------------------allpaths_check_safepts---------------------------- 2245 // Allpaths backwards scan from loop tail, terminating each path at first safepoint 2246 // encountered. Helper for check_safepts. 2247 void IdealLoopTree::allpaths_check_safepts(VectorSet &visited, Node_List &stack) { 2248 assert(stack.size() == 0, "empty stack"); 2249 stack.push(_tail); 2250 visited.clear(); 2251 visited.set(_tail->_idx); 2252 while (stack.size() > 0) { 2253 Node* n = stack.pop(); 2254 if (n->is_Call() && n->as_Call()->guaranteed_safepoint()) { 2255 // Terminate this path 2256 } else if (n->Opcode() == Op_SafePoint) { 2257 if (_phase->get_loop(n) != this) { 2258 if (_required_safept == NULL) _required_safept = new Node_List(); 2259 _required_safept->push(n); // save the one closest to the tail 2260 } 2261 // Terminate this path 2262 } else { 2263 uint start = n->is_Region() ? 1 : 0; 2264 uint end = n->is_Region() && !n->is_Loop() ? n->req() : start + 1; 2265 for (uint i = start; i < end; i++) { 2266 Node* in = n->in(i); 2267 assert(in->is_CFG(), "must be"); 2268 if (!visited.test_set(in->_idx) && is_member(_phase->get_loop(in))) { 2269 stack.push(in); 2270 } 2271 } 2272 } 2273 } 2274 } 2275 2276 //------------------------------check_safepts---------------------------- 2277 // Given dominators, try to find loops with calls that must always be 2278 // executed (call dominates loop tail). These loops do not need non-call 2279 // safepoints (ncsfpt). 2280 // 2281 // A complication is that a safepoint in a inner loop may be needed 2282 // by an outer loop. In the following, the inner loop sees it has a 2283 // call (block 3) on every path from the head (block 2) to the 2284 // backedge (arc 3->2). So it deletes the ncsfpt (non-call safepoint) 2285 // in block 2, _but_ this leaves the outer loop without a safepoint. 2286 // 2287 // entry 0 2288 // | 2289 // v 2290 // outer 1,2 +->1 2291 // | | 2292 // | v 2293 // | 2<---+ ncsfpt in 2 2294 // |_/|\ | 2295 // | v | 2296 // inner 2,3 / 3 | call in 3 2297 // / | | 2298 // v +--+ 2299 // exit 4 2300 // 2301 // 2302 // This method creates a list (_required_safept) of ncsfpt nodes that must 2303 // be protected is created for each loop. When a ncsfpt maybe deleted, it 2304 // is first looked for in the lists for the outer loops of the current loop. 2305 // 2306 // The insights into the problem: 2307 // A) counted loops are okay 2308 // B) innermost loops are okay (only an inner loop can delete 2309 // a ncsfpt needed by an outer loop) 2310 // C) a loop is immune from an inner loop deleting a safepoint 2311 // if the loop has a call on the idom-path 2312 // D) a loop is also immune if it has a ncsfpt (non-call safepoint) on the 2313 // idom-path that is not in a nested loop 2314 // E) otherwise, an ncsfpt on the idom-path that is nested in an inner 2315 // loop needs to be prevented from deletion by an inner loop 2316 // 2317 // There are two analyses: 2318 // 1) The first, and cheaper one, scans the loop body from 2319 // tail to head following the idom (immediate dominator) 2320 // chain, looking for the cases (C,D,E) above. 2321 // Since inner loops are scanned before outer loops, there is summary 2322 // information about inner loops. Inner loops can be skipped over 2323 // when the tail of an inner loop is encountered. 2324 // 2325 // 2) The second, invoked if the first fails to find a call or ncsfpt on 2326 // the idom path (which is rare), scans all predecessor control paths 2327 // from the tail to the head, terminating a path when a call or sfpt 2328 // is encountered, to find the ncsfpt's that are closest to the tail. 2329 // 2330 void IdealLoopTree::check_safepts(VectorSet &visited, Node_List &stack) { 2331 // Bottom up traversal 2332 IdealLoopTree* ch = _child; 2333 if (_child) _child->check_safepts(visited, stack); 2334 if (_next) _next ->check_safepts(visited, stack); 2335 2336 if (!_head->is_CountedLoop() && !_has_sfpt && _parent != NULL && !_irreducible) { 2337 bool has_call = false; // call on dom-path 2338 bool has_local_ncsfpt = false; // ncsfpt on dom-path at this loop depth 2339 Node* nonlocal_ncsfpt = NULL; // ncsfpt on dom-path at a deeper depth 2340 // Scan the dom-path nodes from tail to head 2341 for (Node* n = tail(); n != _head; n = _phase->idom(n)) { 2342 if (n->is_Call() && n->as_Call()->guaranteed_safepoint()) { 2343 has_call = true; 2344 _has_sfpt = 1; // Then no need for a safept! 2345 break; 2346 } else if (n->Opcode() == Op_SafePoint) { 2347 if (_phase->get_loop(n) == this) { 2348 has_local_ncsfpt = true; 2349 break; 2350 } 2351 if (nonlocal_ncsfpt == NULL) { 2352 nonlocal_ncsfpt = n; // save the one closest to the tail 2353 } 2354 } else { 2355 IdealLoopTree* nlpt = _phase->get_loop(n); 2356 if (this != nlpt) { 2357 // If at an inner loop tail, see if the inner loop has already 2358 // recorded seeing a call on the dom-path (and stop.) If not, 2359 // jump to the head of the inner loop. 2360 assert(is_member(nlpt), "nested loop"); 2361 Node* tail = nlpt->_tail; 2362 if (tail->in(0)->is_If()) tail = tail->in(0); 2363 if (n == tail) { 2364 // If inner loop has call on dom-path, so does outer loop 2365 if (nlpt->_has_sfpt) { 2366 has_call = true; 2367 _has_sfpt = 1; 2368 break; 2369 } 2370 // Skip to head of inner loop 2371 assert(_phase->is_dominator(_head, nlpt->_head), "inner head dominated by outer head"); 2372 n = nlpt->_head; 2373 } 2374 } 2375 } 2376 } 2377 // Record safept's that this loop needs preserved when an 2378 // inner loop attempts to delete it's safepoints. 2379 if (_child != NULL && !has_call && !has_local_ncsfpt) { 2380 if (nonlocal_ncsfpt != NULL) { 2381 if (_required_safept == NULL) _required_safept = new Node_List(); 2382 _required_safept->push(nonlocal_ncsfpt); 2383 } else { 2384 // Failed to find a suitable safept on the dom-path. Now use 2385 // an all paths walk from tail to head, looking for safepoints to preserve. 2386 allpaths_check_safepts(visited, stack); 2387 } 2388 } 2389 } 2390 } 2391 2392 //---------------------------is_deleteable_safept---------------------------- 2393 // Is safept not required by an outer loop? 2394 bool PhaseIdealLoop::is_deleteable_safept(Node* sfpt) { 2395 assert(sfpt->Opcode() == Op_SafePoint, ""); 2396 IdealLoopTree* lp = get_loop(sfpt)->_parent; 2397 while (lp != NULL) { 2398 Node_List* sfpts = lp->_required_safept; 2399 if (sfpts != NULL) { 2400 for (uint i = 0; i < sfpts->size(); i++) { 2401 if (sfpt == sfpts->at(i)) 2402 return false; 2403 } 2404 } 2405 lp = lp->_parent; 2406 } 2407 return true; 2408 } 2409 2410 //---------------------------replace_parallel_iv------------------------------- 2411 // Replace parallel induction variable (parallel to trip counter) 2412 void PhaseIdealLoop::replace_parallel_iv(IdealLoopTree *loop) { 2413 assert(loop->_head->is_CountedLoop(), ""); 2414 CountedLoopNode *cl = loop->_head->as_CountedLoop(); 2415 if (!cl->is_valid_counted_loop()) 2416 return; // skip malformed counted loop 2417 Node *incr = cl->incr(); 2418 if (incr == NULL) 2419 return; // Dead loop? 2420 Node *init = cl->init_trip(); 2421 Node *phi = cl->phi(); 2422 int stride_con = cl->stride_con(); 2423 2424 // Visit all children, looking for Phis 2425 for (DUIterator i = cl->outs(); cl->has_out(i); i++) { 2426 Node *out = cl->out(i); 2427 // Look for other phis (secondary IVs). Skip dead ones 2428 if (!out->is_Phi() || out == phi || !has_node(out)) 2429 continue; 2430 PhiNode* phi2 = out->as_Phi(); 2431 Node *incr2 = phi2->in( LoopNode::LoopBackControl ); 2432 // Look for induction variables of the form: X += constant 2433 if (phi2->region() != loop->_head || 2434 incr2->req() != 3 || 2435 incr2->in(1) != phi2 || 2436 incr2 == incr || 2437 incr2->Opcode() != Op_AddI || 2438 !incr2->in(2)->is_Con()) 2439 continue; 2440 2441 // Check for parallel induction variable (parallel to trip counter) 2442 // via an affine function. In particular, count-down loops with 2443 // count-up array indices are common. We only RCE references off 2444 // the trip-counter, so we need to convert all these to trip-counter 2445 // expressions. 2446 Node *init2 = phi2->in( LoopNode::EntryControl ); 2447 int stride_con2 = incr2->in(2)->get_int(); 2448 2449 // The ratio of the two strides cannot be represented as an int 2450 // if stride_con2 is min_int and stride_con is -1. 2451 if (stride_con2 == min_jint && stride_con == -1) { 2452 continue; 2453 } 2454 2455 // The general case here gets a little tricky. We want to find the 2456 // GCD of all possible parallel IV's and make a new IV using this 2457 // GCD for the loop. Then all possible IVs are simple multiples of 2458 // the GCD. In practice, this will cover very few extra loops. 2459 // Instead we require 'stride_con2' to be a multiple of 'stride_con', 2460 // where +/-1 is the common case, but other integer multiples are 2461 // also easy to handle. 2462 int ratio_con = stride_con2/stride_con; 2463 2464 if ((ratio_con * stride_con) == stride_con2) { // Check for exact 2465 #ifndef PRODUCT 2466 if (TraceLoopOpts) { 2467 tty->print("Parallel IV: %d ", phi2->_idx); 2468 loop->dump_head(); 2469 } 2470 #endif 2471 // Convert to using the trip counter. The parallel induction 2472 // variable differs from the trip counter by a loop-invariant 2473 // amount, the difference between their respective initial values. 2474 // It is scaled by the 'ratio_con'. 2475 Node* ratio = _igvn.intcon(ratio_con); 2476 set_ctrl(ratio, C->root()); 2477 Node* ratio_init = new MulINode(init, ratio); 2478 _igvn.register_new_node_with_optimizer(ratio_init, init); 2479 set_early_ctrl(ratio_init); 2480 Node* diff = new SubINode(init2, ratio_init); 2481 _igvn.register_new_node_with_optimizer(diff, init2); 2482 set_early_ctrl(diff); 2483 Node* ratio_idx = new MulINode(phi, ratio); 2484 _igvn.register_new_node_with_optimizer(ratio_idx, phi); 2485 set_ctrl(ratio_idx, cl); 2486 Node* add = new AddINode(ratio_idx, diff); 2487 _igvn.register_new_node_with_optimizer(add); 2488 set_ctrl(add, cl); 2489 _igvn.replace_node( phi2, add ); 2490 // Sometimes an induction variable is unused 2491 if (add->outcnt() == 0) { 2492 _igvn.remove_dead_node(add); 2493 } 2494 --i; // deleted this phi; rescan starting with next position 2495 continue; 2496 } 2497 } 2498 } 2499 2500 void IdealLoopTree::remove_safepoints(PhaseIdealLoop* phase, bool keep_one) { 2501 Node* keep = NULL; 2502 if (keep_one) { 2503 // Look for a safepoint on the idom-path. 2504 for (Node* i = tail(); i != _head; i = phase->idom(i)) { 2505 if (i->Opcode() == Op_SafePoint && phase->get_loop(i) == this) { 2506 keep = i; 2507 break; // Found one 2508 } 2509 } 2510 } 2511 2512 // Don't remove any safepoints if it is requested to keep a single safepoint and 2513 // no safepoint was found on idom-path. It is not safe to remove any safepoint 2514 // in this case since there's no safepoint dominating all paths in the loop body. 2515 bool prune = !keep_one || keep != NULL; 2516 2517 // Delete other safepoints in this loop. 2518 Node_List* sfpts = _safepts; 2519 if (prune && sfpts != NULL) { 2520 assert(keep == NULL || keep->Opcode() == Op_SafePoint, "not safepoint"); 2521 for (uint i = 0; i < sfpts->size(); i++) { 2522 Node* n = sfpts->at(i); 2523 assert(phase->get_loop(n) == this, ""); 2524 if (n != keep && phase->is_deleteable_safept(n)) { 2525 phase->lazy_replace(n, n->in(TypeFunc::Control)); 2526 } 2527 } 2528 } 2529 } 2530 2531 //------------------------------counted_loop----------------------------------- 2532 // Convert to counted loops where possible 2533 void IdealLoopTree::counted_loop( PhaseIdealLoop *phase ) { 2534 2535 // For grins, set the inner-loop flag here 2536 if (!_child) { 2537 if (_head->is_Loop()) _head->as_Loop()->set_inner_loop(); 2538 } 2539 2540 IdealLoopTree* loop = this; 2541 if (_head->is_CountedLoop() || 2542 phase->is_counted_loop(_head, loop)) { 2543 2544 if (LoopStripMiningIter == 0 || (LoopStripMiningIter > 1 && _child == NULL)) { 2545 // Indicate we do not need a safepoint here 2546 _has_sfpt = 1; 2547 } 2548 2549 // Remove safepoints 2550 bool keep_one_sfpt = !(_has_call || _has_sfpt); 2551 remove_safepoints(phase, keep_one_sfpt); 2552 2553 // Look for induction variables 2554 phase->replace_parallel_iv(this); 2555 2556 } else if (_parent != NULL && !_irreducible) { 2557 // Not a counted loop. Keep one safepoint. 2558 bool keep_one_sfpt = true; 2559 remove_safepoints(phase, keep_one_sfpt); 2560 } 2561 2562 // Recursively 2563 assert(loop->_child != this || (loop->_head->as_Loop()->is_OuterStripMinedLoop() && _head->as_CountedLoop()->is_strip_mined()), "what kind of loop was added?"); 2564 assert(loop->_child != this || (loop->_child->_child == NULL && loop->_child->_next == NULL), "would miss some loops"); 2565 if (loop->_child && loop->_child != this) loop->_child->counted_loop(phase); 2566 if (loop->_next) loop->_next ->counted_loop(phase); 2567 } 2568 2569 2570 // The Estimated Loop Clone Size: 2571 // CloneFactor * (~112% * BodySize + BC) + CC + FanOutTerm, 2572 // where BC and CC are totally ad-hoc/magic "body" and "clone" constants, 2573 // respectively, used to ensure that the node usage estimates made are on the 2574 // safe side, for the most part. The FanOutTerm is an attempt to estimate the 2575 // possible additional/excessive nodes generated due to data and control flow 2576 // merging, for edges reaching outside the loop. 2577 uint IdealLoopTree::est_loop_clone_sz(uint factor) const { 2578 2579 precond(0 < factor && factor < 16); 2580 2581 uint const bc = 13; 2582 uint const cc = 17; 2583 uint const sz = _body.size() + (_body.size() + 7) / 8; 2584 uint estimate = factor * (sz + bc) + cc; 2585 2586 assert((estimate - cc) / factor == sz + bc, "overflow"); 2587 2588 return estimate + est_loop_flow_merge_sz(); 2589 } 2590 2591 // The Estimated Loop (full-) Unroll Size: 2592 // UnrollFactor * (~106% * BodySize) + CC + FanOutTerm, 2593 // where CC is a (totally) ad-hoc/magic "clone" constant, used to ensure that 2594 // node usage estimates made are on the safe side, for the most part. This is 2595 // a "light" version of the loop clone size calculation (above), based on the 2596 // assumption that most of the loop-construct overhead will be unraveled when 2597 // (fully) unrolled. Defined for unroll factors larger or equal to one (>=1), 2598 // including an overflow check and returning UINT_MAX in case of an overflow. 2599 uint IdealLoopTree::est_loop_unroll_sz(uint factor) const { 2600 2601 precond(factor > 0); 2602 2603 // Take into account that after unroll conjoined heads and tails will fold. 2604 uint const b0 = _body.size() - EMPTY_LOOP_SIZE; 2605 uint const cc = 7; 2606 uint const sz = b0 + (b0 + 15) / 16; 2607 uint estimate = factor * sz + cc; 2608 2609 if ((estimate - cc) / factor != sz) { 2610 return UINT_MAX; 2611 } 2612 2613 return estimate + est_loop_flow_merge_sz(); 2614 } 2615 2616 // Estimate the growth effect (in nodes) of merging control and data flow when 2617 // cloning a loop body, based on the amount of control and data flow reaching 2618 // outside of the (current) loop body. 2619 uint IdealLoopTree::est_loop_flow_merge_sz() const { 2620 2621 uint ctrl_edge_out_cnt = 0; 2622 uint data_edge_out_cnt = 0; 2623 2624 for (uint i = 0; i < _body.size(); i++) { 2625 Node* node = _body.at(i); 2626 uint outcnt = node->outcnt(); 2627 2628 for (uint k = 0; k < outcnt; k++) { 2629 Node* out = node->raw_out(k); 2630 if (out == NULL) continue; 2631 if (out->is_CFG()) { 2632 if (!is_member(_phase->get_loop(out))) { 2633 ctrl_edge_out_cnt++; 2634 } 2635 } else if (_phase->has_ctrl(out)) { 2636 Node* ctrl = _phase->get_ctrl(out); 2637 assert(ctrl != NULL, "must be"); 2638 assert(ctrl->is_CFG(), "must be"); 2639 if (!is_member(_phase->get_loop(ctrl))) { 2640 data_edge_out_cnt++; 2641 } 2642 } 2643 } 2644 } 2645 // Use data and control count (x2.0) in estimate iff both are > 0. This is 2646 // a rather pessimistic estimate for the most part, in particular for some 2647 // complex loops, but still not enough to capture all loops. 2648 if (ctrl_edge_out_cnt > 0 && data_edge_out_cnt > 0) { 2649 return 2 * (ctrl_edge_out_cnt + data_edge_out_cnt); 2650 } 2651 return 0; 2652 } 2653 2654 #ifndef PRODUCT 2655 //------------------------------dump_head-------------------------------------- 2656 // Dump 1 liner for loop header info 2657 void IdealLoopTree::dump_head() const { 2658 tty->sp(2 * _nest); 2659 tty->print("Loop: N%d/N%d ", _head->_idx, _tail->_idx); 2660 if (_irreducible) tty->print(" IRREDUCIBLE"); 2661 Node* entry = _head->is_Loop() ? _head->as_Loop()->skip_strip_mined(-1)->in(LoopNode::EntryControl) : _head->in(LoopNode::EntryControl); 2662 Node* predicate = PhaseIdealLoop::find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check); 2663 if (predicate != NULL ) { 2664 tty->print(" limit_check"); 2665 entry = PhaseIdealLoop::skip_loop_predicates(entry); 2666 } 2667 if (UseProfiledLoopPredicate) { 2668 predicate = PhaseIdealLoop::find_predicate_insertion_point(entry, Deoptimization::Reason_profile_predicate); 2669 if (predicate != NULL) { 2670 tty->print(" profile_predicated"); 2671 entry = PhaseIdealLoop::skip_loop_predicates(entry); 2672 } 2673 } 2674 if (UseLoopPredicate) { 2675 predicate = PhaseIdealLoop::find_predicate_insertion_point(entry, Deoptimization::Reason_predicate); 2676 if (predicate != NULL) { 2677 tty->print(" predicated"); 2678 } 2679 } 2680 if (_head->is_CountedLoop()) { 2681 CountedLoopNode *cl = _head->as_CountedLoop(); 2682 tty->print(" counted"); 2683 2684 Node* init_n = cl->init_trip(); 2685 if (init_n != NULL && init_n->is_Con()) 2686 tty->print(" [%d,", cl->init_trip()->get_int()); 2687 else 2688 tty->print(" [int,"); 2689 Node* limit_n = cl->limit(); 2690 if (limit_n != NULL && limit_n->is_Con()) 2691 tty->print("%d),", cl->limit()->get_int()); 2692 else 2693 tty->print("int),"); 2694 int stride_con = cl->stride_con(); 2695 if (stride_con > 0) tty->print("+"); 2696 tty->print("%d", stride_con); 2697 2698 tty->print(" (%0.f iters) ", cl->profile_trip_cnt()); 2699 2700 if (cl->is_pre_loop ()) tty->print(" pre" ); 2701 if (cl->is_main_loop()) tty->print(" main"); 2702 if (cl->is_post_loop()) tty->print(" post"); 2703 if (cl->is_vectorized_loop()) tty->print(" vector"); 2704 if (cl->range_checks_present()) tty->print(" rc "); 2705 if (cl->is_multiversioned()) tty->print(" multi "); 2706 } 2707 if (_has_call) tty->print(" has_call"); 2708 if (_has_sfpt) tty->print(" has_sfpt"); 2709 if (_rce_candidate) tty->print(" rce"); 2710 if (_safepts != NULL && _safepts->size() > 0) { 2711 tty->print(" sfpts={"); _safepts->dump_simple(); tty->print(" }"); 2712 } 2713 if (_required_safept != NULL && _required_safept->size() > 0) { 2714 tty->print(" req={"); _required_safept->dump_simple(); tty->print(" }"); 2715 } 2716 if (Verbose) { 2717 tty->print(" body={"); _body.dump_simple(); tty->print(" }"); 2718 } 2719 if (_head->is_Loop() && _head->as_Loop()->is_strip_mined()) { 2720 tty->print(" strip_mined"); 2721 } 2722 tty->cr(); 2723 } 2724 2725 //------------------------------dump------------------------------------------- 2726 // Dump loops by loop tree 2727 void IdealLoopTree::dump() const { 2728 dump_head(); 2729 if (_child) _child->dump(); 2730 if (_next) _next ->dump(); 2731 } 2732 2733 #endif 2734 2735 static void log_loop_tree(IdealLoopTree* root, IdealLoopTree* loop, CompileLog* log) { 2736 if (loop == root) { 2737 if (loop->_child != NULL) { 2738 log->begin_head("loop_tree"); 2739 log->end_head(); 2740 if( loop->_child ) log_loop_tree(root, loop->_child, log); 2741 log->tail("loop_tree"); 2742 assert(loop->_next == NULL, "what?"); 2743 } 2744 } else { 2745 Node* head = loop->_head; 2746 log->begin_head("loop"); 2747 log->print(" idx='%d' ", head->_idx); 2748 if (loop->_irreducible) log->print("irreducible='1' "); 2749 if (head->is_Loop()) { 2750 if (head->as_Loop()->is_inner_loop()) log->print("inner_loop='1' "); 2751 if (head->as_Loop()->is_partial_peel_loop()) log->print("partial_peel_loop='1' "); 2752 } 2753 if (head->is_CountedLoop()) { 2754 CountedLoopNode* cl = head->as_CountedLoop(); 2755 if (cl->is_pre_loop()) log->print("pre_loop='%d' ", cl->main_idx()); 2756 if (cl->is_main_loop()) log->print("main_loop='%d' ", cl->_idx); 2757 if (cl->is_post_loop()) log->print("post_loop='%d' ", cl->main_idx()); 2758 } 2759 log->end_head(); 2760 if( loop->_child ) log_loop_tree(root, loop->_child, log); 2761 log->tail("loop"); 2762 if( loop->_next ) log_loop_tree(root, loop->_next, log); 2763 } 2764 } 2765 2766 //---------------------collect_potentially_useful_predicates----------------------- 2767 // Helper function to collect potentially useful predicates to prevent them from 2768 // being eliminated by PhaseIdealLoop::eliminate_useless_predicates 2769 void PhaseIdealLoop::collect_potentially_useful_predicates( 2770 IdealLoopTree * loop, Unique_Node_List &useful_predicates) { 2771 if (loop->_child) { // child 2772 collect_potentially_useful_predicates(loop->_child, useful_predicates); 2773 } 2774 2775 // self (only loops that we can apply loop predication may use their predicates) 2776 if (loop->_head->is_Loop() && 2777 !loop->_irreducible && 2778 !loop->tail()->is_top()) { 2779 LoopNode* lpn = loop->_head->as_Loop(); 2780 Node* entry = lpn->in(LoopNode::EntryControl); 2781 Node* predicate_proj = find_predicate(entry); // loop_limit_check first 2782 if (predicate_proj != NULL) { // right pattern that can be used by loop predication 2783 assert(entry->in(0)->in(1)->in(1)->Opcode() == Op_Opaque1, "must be"); 2784 useful_predicates.push(entry->in(0)->in(1)->in(1)); // good one 2785 entry = skip_loop_predicates(entry); 2786 } 2787 if (UseProfiledLoopPredicate) { 2788 predicate_proj = find_predicate(entry); // Predicate 2789 if (predicate_proj != NULL) { 2790 useful_predicates.push(entry->in(0)->in(1)->in(1)); // good one 2791 entry = skip_loop_predicates(entry); 2792 } 2793 } 2794 predicate_proj = find_predicate(entry); // Predicate 2795 if (predicate_proj != NULL) { 2796 useful_predicates.push(entry->in(0)->in(1)->in(1)); // good one 2797 } 2798 } 2799 2800 if (loop->_next) { // sibling 2801 collect_potentially_useful_predicates(loop->_next, useful_predicates); 2802 } 2803 } 2804 2805 //------------------------eliminate_useless_predicates----------------------------- 2806 // Eliminate all inserted predicates if they could not be used by loop predication. 2807 // Note: it will also eliminates loop limits check predicate since it also uses 2808 // Opaque1 node (see Parse::add_predicate()). 2809 void PhaseIdealLoop::eliminate_useless_predicates() { 2810 if (C->predicate_count() == 0) 2811 return; // no predicate left 2812 2813 Unique_Node_List useful_predicates; // to store useful predicates 2814 if (C->has_loops()) { 2815 collect_potentially_useful_predicates(_ltree_root->_child, useful_predicates); 2816 } 2817 2818 for (int i = C->predicate_count(); i > 0; i--) { 2819 Node * n = C->predicate_opaque1_node(i-1); 2820 assert(n->Opcode() == Op_Opaque1, "must be"); 2821 if (!useful_predicates.member(n)) { // not in the useful list 2822 _igvn.replace_node(n, n->in(1)); 2823 } 2824 } 2825 } 2826 2827 //------------------------process_expensive_nodes----------------------------- 2828 // Expensive nodes have their control input set to prevent the GVN 2829 // from commoning them and as a result forcing the resulting node to 2830 // be in a more frequent path. Use CFG information here, to change the 2831 // control inputs so that some expensive nodes can be commoned while 2832 // not executed more frequently. 2833 bool PhaseIdealLoop::process_expensive_nodes() { 2834 assert(OptimizeExpensiveOps, "optimization off?"); 2835 2836 // Sort nodes to bring similar nodes together 2837 C->sort_expensive_nodes(); 2838 2839 bool progress = false; 2840 2841 for (int i = 0; i < C->expensive_count(); ) { 2842 Node* n = C->expensive_node(i); 2843 int start = i; 2844 // Find nodes similar to n 2845 i++; 2846 for (; i < C->expensive_count() && Compile::cmp_expensive_nodes(n, C->expensive_node(i)) == 0; i++); 2847 int end = i; 2848 // And compare them two by two 2849 for (int j = start; j < end; j++) { 2850 Node* n1 = C->expensive_node(j); 2851 if (is_node_unreachable(n1)) { 2852 continue; 2853 } 2854 for (int k = j+1; k < end; k++) { 2855 Node* n2 = C->expensive_node(k); 2856 if (is_node_unreachable(n2)) { 2857 continue; 2858 } 2859 2860 assert(n1 != n2, "should be pair of nodes"); 2861 2862 Node* c1 = n1->in(0); 2863 Node* c2 = n2->in(0); 2864 2865 Node* parent_c1 = c1; 2866 Node* parent_c2 = c2; 2867 2868 // The call to get_early_ctrl_for_expensive() moves the 2869 // expensive nodes up but stops at loops that are in a if 2870 // branch. See whether we can exit the loop and move above the 2871 // If. 2872 if (c1->is_Loop()) { 2873 parent_c1 = c1->in(1); 2874 } 2875 if (c2->is_Loop()) { 2876 parent_c2 = c2->in(1); 2877 } 2878 2879 if (parent_c1 == parent_c2) { 2880 _igvn._worklist.push(n1); 2881 _igvn._worklist.push(n2); 2882 continue; 2883 } 2884 2885 // Look for identical expensive node up the dominator chain. 2886 if (is_dominator(c1, c2)) { 2887 c2 = c1; 2888 } else if (is_dominator(c2, c1)) { 2889 c1 = c2; 2890 } else if (parent_c1->is_Proj() && parent_c1->in(0)->is_If() && 2891 parent_c2->is_Proj() && parent_c1->in(0) == parent_c2->in(0)) { 2892 // Both branches have the same expensive node so move it up 2893 // before the if. 2894 c1 = c2 = idom(parent_c1->in(0)); 2895 } 2896 // Do the actual moves 2897 if (n1->in(0) != c1) { 2898 _igvn.hash_delete(n1); 2899 n1->set_req(0, c1); 2900 _igvn.hash_insert(n1); 2901 _igvn._worklist.push(n1); 2902 progress = true; 2903 } 2904 if (n2->in(0) != c2) { 2905 _igvn.hash_delete(n2); 2906 n2->set_req(0, c2); 2907 _igvn.hash_insert(n2); 2908 _igvn._worklist.push(n2); 2909 progress = true; 2910 } 2911 } 2912 } 2913 } 2914 2915 return progress; 2916 } 2917 2918 2919 //============================================================================= 2920 //----------------------------build_and_optimize------------------------------- 2921 // Create a PhaseLoop. Build the ideal Loop tree. Map each Ideal Node to 2922 // its corresponding LoopNode. If 'optimize' is true, do some loop cleanups. 2923 void PhaseIdealLoop::build_and_optimize(LoopOptsMode mode) { 2924 bool do_split_ifs = (mode == LoopOptsDefault); 2925 bool skip_loop_opts = (mode == LoopOptsNone); 2926 2927 int old_progress = C->major_progress(); 2928 uint orig_worklist_size = _igvn._worklist.size(); 2929 2930 // Reset major-progress flag for the driver's heuristics 2931 C->clear_major_progress(); 2932 2933 #ifndef PRODUCT 2934 // Capture for later assert 2935 uint unique = C->unique(); 2936 _loop_invokes++; 2937 _loop_work += unique; 2938 #endif 2939 2940 // True if the method has at least 1 irreducible loop 2941 _has_irreducible_loops = false; 2942 2943 _created_loop_node = false; 2944 2945 Arena *a = Thread::current()->resource_area(); 2946 VectorSet visited(a); 2947 // Pre-grow the mapping from Nodes to IdealLoopTrees. 2948 _nodes.map(C->unique(), NULL); 2949 memset(_nodes.adr(), 0, wordSize * C->unique()); 2950 2951 // Pre-build the top-level outermost loop tree entry 2952 _ltree_root = new IdealLoopTree( this, C->root(), C->root() ); 2953 // Do not need a safepoint at the top level 2954 _ltree_root->_has_sfpt = 1; 2955 2956 // Initialize Dominators. 2957 // Checked in clone_loop_predicate() during beautify_loops(). 2958 _idom_size = 0; 2959 _idom = NULL; 2960 _dom_depth = NULL; 2961 _dom_stk = NULL; 2962 2963 // Empty pre-order array 2964 allocate_preorders(); 2965 2966 // Build a loop tree on the fly. Build a mapping from CFG nodes to 2967 // IdealLoopTree entries. Data nodes are NOT walked. 2968 build_loop_tree(); 2969 // Check for bailout, and return 2970 if (C->failing()) { 2971 return; 2972 } 2973 2974 // No loops after all 2975 if( !_ltree_root->_child && !_verify_only ) C->set_has_loops(false); 2976 2977 // There should always be an outer loop containing the Root and Return nodes. 2978 // If not, we have a degenerate empty program. Bail out in this case. 2979 if (!has_node(C->root())) { 2980 if (!_verify_only) { 2981 C->clear_major_progress(); 2982 C->record_method_not_compilable("empty program detected during loop optimization"); 2983 } 2984 return; 2985 } 2986 2987 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2(); 2988 // Nothing to do, so get out 2989 bool stop_early = !C->has_loops() && !skip_loop_opts && !do_split_ifs && !_verify_me && !_verify_only && 2990 !bs->is_gc_specific_loop_opts_pass(mode); 2991 bool do_expensive_nodes = C->should_optimize_expensive_nodes(_igvn); 2992 bool strip_mined_loops_expanded = bs->strip_mined_loops_expanded(mode); 2993 if (stop_early && !do_expensive_nodes) { 2994 _igvn.optimize(); // Cleanup NeverBranches 2995 return; 2996 } 2997 2998 // Set loop nesting depth 2999 _ltree_root->set_nest( 0 ); 3000 3001 // Split shared headers and insert loop landing pads. 3002 // Do not bother doing this on the Root loop of course. 3003 if( !_verify_me && !_verify_only && _ltree_root->_child ) { 3004 C->print_method(PHASE_BEFORE_BEAUTIFY_LOOPS, 3); 3005 if( _ltree_root->_child->beautify_loops( this ) ) { 3006 // Re-build loop tree! 3007 _ltree_root->_child = NULL; 3008 _nodes.clear(); 3009 reallocate_preorders(); 3010 build_loop_tree(); 3011 // Check for bailout, and return 3012 if (C->failing()) { 3013 return; 3014 } 3015 // Reset loop nesting depth 3016 _ltree_root->set_nest( 0 ); 3017 3018 C->print_method(PHASE_AFTER_BEAUTIFY_LOOPS, 3); 3019 } 3020 } 3021 3022 // Build Dominators for elision of NULL checks & loop finding. 3023 // Since nodes do not have a slot for immediate dominator, make 3024 // a persistent side array for that info indexed on node->_idx. 3025 _idom_size = C->unique(); 3026 _idom = NEW_RESOURCE_ARRAY( Node*, _idom_size ); 3027 _dom_depth = NEW_RESOURCE_ARRAY( uint, _idom_size ); 3028 _dom_stk = NULL; // Allocated on demand in recompute_dom_depth 3029 memset( _dom_depth, 0, _idom_size * sizeof(uint) ); 3030 3031 Dominators(); 3032 3033 if (!_verify_only) { 3034 // As a side effect, Dominators removed any unreachable CFG paths 3035 // into RegionNodes. It doesn't do this test against Root, so 3036 // we do it here. 3037 for( uint i = 1; i < C->root()->req(); i++ ) { 3038 if( !_nodes[C->root()->in(i)->_idx] ) { // Dead path into Root? 3039 _igvn.delete_input_of(C->root(), i); 3040 i--; // Rerun same iteration on compressed edges 3041 } 3042 } 3043 3044 // Given dominators, try to find inner loops with calls that must 3045 // always be executed (call dominates loop tail). These loops do 3046 // not need a separate safepoint. 3047 Node_List cisstack(a); 3048 _ltree_root->check_safepts(visited, cisstack); 3049 } 3050 3051 // Walk the DATA nodes and place into loops. Find earliest control 3052 // node. For CFG nodes, the _nodes array starts out and remains 3053 // holding the associated IdealLoopTree pointer. For DATA nodes, the 3054 // _nodes array holds the earliest legal controlling CFG node. 3055 3056 // Allocate stack with enough space to avoid frequent realloc 3057 int stack_size = (C->live_nodes() >> 1) + 16; // (live_nodes>>1)+16 from Java2D stats 3058 Node_Stack nstack( a, stack_size ); 3059 3060 visited.clear(); 3061 Node_List worklist(a); 3062 // Don't need C->root() on worklist since 3063 // it will be processed among C->top() inputs 3064 worklist.push(C->top()); 3065 visited.set(C->top()->_idx); // Set C->top() as visited now 3066 build_loop_early( visited, worklist, nstack ); 3067 3068 // Given early legal placement, try finding counted loops. This placement 3069 // is good enough to discover most loop invariants. 3070 if (!_verify_me && !_verify_only && !strip_mined_loops_expanded) { 3071 _ltree_root->counted_loop( this ); 3072 } 3073 3074 // Find latest loop placement. Find ideal loop placement. 3075 visited.clear(); 3076 init_dom_lca_tags(); 3077 // Need C->root() on worklist when processing outs 3078 worklist.push(C->root()); 3079 NOT_PRODUCT( C->verify_graph_edges(); ) 3080 worklist.push(C->top()); 3081 build_loop_late( visited, worklist, nstack ); 3082 3083 if (_verify_only) { 3084 C->restore_major_progress(old_progress); 3085 assert(C->unique() == unique, "verification mode made Nodes? ? ?"); 3086 assert(_igvn._worklist.size() == orig_worklist_size, "shouldn't push anything"); 3087 return; 3088 } 3089 3090 // clear out the dead code after build_loop_late 3091 while (_deadlist.size()) { 3092 _igvn.remove_globally_dead_node(_deadlist.pop()); 3093 } 3094 3095 if (stop_early) { 3096 assert(do_expensive_nodes, "why are we here?"); 3097 if (process_expensive_nodes()) { 3098 // If we made some progress when processing expensive nodes then 3099 // the IGVN may modify the graph in a way that will allow us to 3100 // make some more progress: we need to try processing expensive 3101 // nodes again. 3102 C->set_major_progress(); 3103 } 3104 _igvn.optimize(); 3105 return; 3106 } 3107 3108 // Some parser-inserted loop predicates could never be used by loop 3109 // predication or they were moved away from loop during some optimizations. 3110 // For example, peeling. Eliminate them before next loop optimizations. 3111 eliminate_useless_predicates(); 3112 3113 #ifndef PRODUCT 3114 C->verify_graph_edges(); 3115 if (_verify_me) { // Nested verify pass? 3116 // Check to see if the verify mode is broken 3117 assert(C->unique() == unique, "non-optimize mode made Nodes? ? ?"); 3118 return; 3119 } 3120 if (VerifyLoopOptimizations) verify(); 3121 if (TraceLoopOpts && C->has_loops()) { 3122 _ltree_root->dump(); 3123 } 3124 #endif 3125 3126 if (skip_loop_opts) { 3127 // restore major progress flag 3128 C->restore_major_progress(old_progress); 3129 3130 // Cleanup any modified bits 3131 _igvn.optimize(); 3132 3133 if (C->log() != NULL) { 3134 log_loop_tree(_ltree_root, _ltree_root, C->log()); 3135 } 3136 return; 3137 } 3138 3139 if (mode == LoopOptsMaxUnroll) { 3140 for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) { 3141 IdealLoopTree* lpt = iter.current(); 3142 if (lpt->is_innermost() && lpt->_allow_optimizations && !lpt->_has_call && lpt->is_counted()) { 3143 lpt->compute_trip_count(this); 3144 if (!lpt->do_one_iteration_loop(this) && 3145 !lpt->do_remove_empty_loop(this)) { 3146 AutoNodeBudget node_budget(this); 3147 if (lpt->_head->as_CountedLoop()->is_normal_loop() && 3148 lpt->policy_maximally_unroll(this)) { 3149 memset( worklist.adr(), 0, worklist.Size()*sizeof(Node*) ); 3150 do_maximally_unroll(lpt, worklist); 3151 } 3152 } 3153 } 3154 } 3155 3156 C->restore_major_progress(old_progress); 3157 3158 _igvn.optimize(); 3159 3160 if (C->log() != NULL) { 3161 log_loop_tree(_ltree_root, _ltree_root, C->log()); 3162 } 3163 return; 3164 } 3165 3166 if (bs->optimize_loops(this, mode, visited, nstack, worklist)) { 3167 _igvn.optimize(); 3168 if (C->log() != NULL) { 3169 log_loop_tree(_ltree_root, _ltree_root, C->log()); 3170 } 3171 return; 3172 } 3173 3174 if (ReassociateInvariants) { 3175 // Reassociate invariants and prep for split_thru_phi 3176 for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) { 3177 IdealLoopTree* lpt = iter.current(); 3178 bool is_counted = lpt->is_counted(); 3179 if (!is_counted || !lpt->is_innermost()) continue; 3180 3181 // check for vectorized loops, any reassociation of invariants was already done 3182 if (is_counted && lpt->_head->as_CountedLoop()->is_unroll_only()) { 3183 continue; 3184 } else { 3185 AutoNodeBudget node_budget(this); 3186 lpt->reassociate_invariants(this); 3187 } 3188 // Because RCE opportunities can be masked by split_thru_phi, 3189 // look for RCE candidates and inhibit split_thru_phi 3190 // on just their loop-phi's for this pass of loop opts 3191 if (SplitIfBlocks && do_split_ifs) { 3192 AutoNodeBudget node_budget(this, AutoNodeBudget::NO_BUDGET_CHECK); 3193 if (lpt->policy_range_check(this)) { 3194 lpt->_rce_candidate = 1; // = true 3195 } 3196 } 3197 } 3198 } 3199 3200 // Check for aggressive application of split-if and other transforms 3201 // that require basic-block info (like cloning through Phi's) 3202 if( SplitIfBlocks && do_split_ifs ) { 3203 visited.clear(); 3204 split_if_with_blocks( visited, nstack); 3205 NOT_PRODUCT( if( VerifyLoopOptimizations ) verify(); ); 3206 } 3207 3208 if (!C->major_progress() && do_expensive_nodes && process_expensive_nodes()) { 3209 C->set_major_progress(); 3210 } 3211 3212 // Perform loop predication before iteration splitting 3213 if (C->has_loops() && !C->major_progress() && (C->predicate_count() > 0)) { 3214 _ltree_root->_child->loop_predication(this); 3215 } 3216 3217 if (OptimizeFill && UseLoopPredicate && C->has_loops() && !C->major_progress()) { 3218 if (do_intrinsify_fill()) { 3219 C->set_major_progress(); 3220 } 3221 } 3222 3223 // Perform iteration-splitting on inner loops. Split iterations to avoid 3224 // range checks or one-shot null checks. 3225 3226 // If split-if's didn't hack the graph too bad (no CFG changes) 3227 // then do loop opts. 3228 if (C->has_loops() && !C->major_progress()) { 3229 memset( worklist.adr(), 0, worklist.Size()*sizeof(Node*) ); 3230 _ltree_root->_child->iteration_split( this, worklist ); 3231 // No verify after peeling! GCM has hoisted code out of the loop. 3232 // After peeling, the hoisted code could sink inside the peeled area. 3233 // The peeling code does not try to recompute the best location for 3234 // all the code before the peeled area, so the verify pass will always 3235 // complain about it. 3236 } 3237 // Do verify graph edges in any case 3238 NOT_PRODUCT( C->verify_graph_edges(); ); 3239 3240 if (!do_split_ifs) { 3241 // We saw major progress in Split-If to get here. We forced a 3242 // pass with unrolling and not split-if, however more split-if's 3243 // might make progress. If the unrolling didn't make progress 3244 // then the major-progress flag got cleared and we won't try 3245 // another round of Split-If. In particular the ever-common 3246 // instance-of/check-cast pattern requires at least 2 rounds of 3247 // Split-If to clear out. 3248 C->set_major_progress(); 3249 } 3250 3251 // Repeat loop optimizations if new loops were seen 3252 if (created_loop_node()) { 3253 C->set_major_progress(); 3254 } 3255 3256 // Keep loop predicates and perform optimizations with them 3257 // until no more loop optimizations could be done. 3258 // After that switch predicates off and do more loop optimizations. 3259 if (!C->major_progress() && (C->predicate_count() > 0)) { 3260 C->cleanup_loop_predicates(_igvn); 3261 if (TraceLoopOpts) { 3262 tty->print_cr("PredicatesOff"); 3263 } 3264 C->set_major_progress(); 3265 } 3266 3267 // Convert scalar to superword operations at the end of all loop opts. 3268 if (UseSuperWord && C->has_loops() && !C->major_progress()) { 3269 // SuperWord transform 3270 SuperWord sw(this); 3271 for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) { 3272 IdealLoopTree* lpt = iter.current(); 3273 if (lpt->is_counted()) { 3274 CountedLoopNode *cl = lpt->_head->as_CountedLoop(); 3275 3276 if (PostLoopMultiversioning && cl->is_rce_post_loop() && !cl->is_vectorized_loop()) { 3277 // Check that the rce'd post loop is encountered first, multiversion after all 3278 // major main loop optimization are concluded 3279 if (!C->major_progress()) { 3280 IdealLoopTree *lpt_next = lpt->_next; 3281 if (lpt_next && lpt_next->is_counted()) { 3282 CountedLoopNode *cl = lpt_next->_head->as_CountedLoop(); 3283 has_range_checks(lpt_next); 3284 if (cl->is_post_loop() && cl->range_checks_present()) { 3285 if (!cl->is_multiversioned()) { 3286 if (multi_version_post_loops(lpt, lpt_next) == false) { 3287 // Cause the rce loop to be optimized away if we fail 3288 cl->mark_is_multiversioned(); 3289 cl->set_slp_max_unroll(0); 3290 poison_rce_post_loop(lpt); 3291 } 3292 } 3293 } 3294 } 3295 sw.transform_loop(lpt, true); 3296 } 3297 } else if (cl->is_main_loop()) { 3298 sw.transform_loop(lpt, true); 3299 } 3300 } 3301 } 3302 } 3303 3304 // Cleanup any modified bits 3305 _igvn.optimize(); 3306 3307 // disable assert until issue with split_flow_path is resolved (6742111) 3308 // assert(!_has_irreducible_loops || C->parsed_irreducible_loop() || C->is_osr_compilation(), 3309 // "shouldn't introduce irreducible loops"); 3310 3311 if (C->log() != NULL) { 3312 log_loop_tree(_ltree_root, _ltree_root, C->log()); 3313 } 3314 } 3315 3316 #ifndef PRODUCT 3317 //------------------------------print_statistics------------------------------- 3318 int PhaseIdealLoop::_loop_invokes=0;// Count of PhaseIdealLoop invokes 3319 int PhaseIdealLoop::_loop_work=0; // Sum of PhaseIdealLoop x unique 3320 void PhaseIdealLoop::print_statistics() { 3321 tty->print_cr("PhaseIdealLoop=%d, sum _unique=%d", _loop_invokes, _loop_work); 3322 } 3323 3324 //------------------------------verify----------------------------------------- 3325 // Build a verify-only PhaseIdealLoop, and see that it agrees with me. 3326 static int fail; // debug only, so its multi-thread dont care 3327 void PhaseIdealLoop::verify() const { 3328 int old_progress = C->major_progress(); 3329 ResourceMark rm; 3330 PhaseIdealLoop loop_verify( _igvn, this ); 3331 VectorSet visited(Thread::current()->resource_area()); 3332 3333 fail = 0; 3334 verify_compare( C->root(), &loop_verify, visited ); 3335 assert( fail == 0, "verify loops failed" ); 3336 // Verify loop structure is the same 3337 _ltree_root->verify_tree(loop_verify._ltree_root, NULL); 3338 // Reset major-progress. It was cleared by creating a verify version of 3339 // PhaseIdealLoop. 3340 C->restore_major_progress(old_progress); 3341 } 3342 3343 //------------------------------verify_compare--------------------------------- 3344 // Make sure me and the given PhaseIdealLoop agree on key data structures 3345 void PhaseIdealLoop::verify_compare( Node *n, const PhaseIdealLoop *loop_verify, VectorSet &visited ) const { 3346 if( !n ) return; 3347 if( visited.test_set( n->_idx ) ) return; 3348 if( !_nodes[n->_idx] ) { // Unreachable 3349 assert( !loop_verify->_nodes[n->_idx], "both should be unreachable" ); 3350 return; 3351 } 3352 3353 uint i; 3354 for( i = 0; i < n->req(); i++ ) 3355 verify_compare( n->in(i), loop_verify, visited ); 3356 3357 // Check the '_nodes' block/loop structure 3358 i = n->_idx; 3359 if( has_ctrl(n) ) { // We have control; verify has loop or ctrl 3360 if( _nodes[i] != loop_verify->_nodes[i] && 3361 get_ctrl_no_update(n) != loop_verify->get_ctrl_no_update(n) ) { 3362 tty->print("Mismatched control setting for: "); 3363 n->dump(); 3364 if( fail++ > 10 ) return; 3365 Node *c = get_ctrl_no_update(n); 3366 tty->print("We have it as: "); 3367 if( c->in(0) ) c->dump(); 3368 else tty->print_cr("N%d",c->_idx); 3369 tty->print("Verify thinks: "); 3370 if( loop_verify->has_ctrl(n) ) 3371 loop_verify->get_ctrl_no_update(n)->dump(); 3372 else 3373 loop_verify->get_loop_idx(n)->dump(); 3374 tty->cr(); 3375 } 3376 } else { // We have a loop 3377 IdealLoopTree *us = get_loop_idx(n); 3378 if( loop_verify->has_ctrl(n) ) { 3379 tty->print("Mismatched loop setting for: "); 3380 n->dump(); 3381 if( fail++ > 10 ) return; 3382 tty->print("We have it as: "); 3383 us->dump(); 3384 tty->print("Verify thinks: "); 3385 loop_verify->get_ctrl_no_update(n)->dump(); 3386 tty->cr(); 3387 } else if (!C->major_progress()) { 3388 // Loop selection can be messed up if we did a major progress 3389 // operation, like split-if. Do not verify in that case. 3390 IdealLoopTree *them = loop_verify->get_loop_idx(n); 3391 if( us->_head != them->_head || us->_tail != them->_tail ) { 3392 tty->print("Unequals loops for: "); 3393 n->dump(); 3394 if( fail++ > 10 ) return; 3395 tty->print("We have it as: "); 3396 us->dump(); 3397 tty->print("Verify thinks: "); 3398 them->dump(); 3399 tty->cr(); 3400 } 3401 } 3402 } 3403 3404 // Check for immediate dominators being equal 3405 if( i >= _idom_size ) { 3406 if( !n->is_CFG() ) return; 3407 tty->print("CFG Node with no idom: "); 3408 n->dump(); 3409 return; 3410 } 3411 if( !n->is_CFG() ) return; 3412 if( n == C->root() ) return; // No IDOM here 3413 3414 assert(n->_idx == i, "sanity"); 3415 Node *id = idom_no_update(n); 3416 if( id != loop_verify->idom_no_update(n) ) { 3417 tty->print("Unequals idoms for: "); 3418 n->dump(); 3419 if( fail++ > 10 ) return; 3420 tty->print("We have it as: "); 3421 id->dump(); 3422 tty->print("Verify thinks: "); 3423 loop_verify->idom_no_update(n)->dump(); 3424 tty->cr(); 3425 } 3426 3427 } 3428 3429 //------------------------------verify_tree------------------------------------ 3430 // Verify that tree structures match. Because the CFG can change, siblings 3431 // within the loop tree can be reordered. We attempt to deal with that by 3432 // reordering the verify's loop tree if possible. 3433 void IdealLoopTree::verify_tree(IdealLoopTree *loop, const IdealLoopTree *parent) const { 3434 assert( _parent == parent, "Badly formed loop tree" ); 3435 3436 // Siblings not in same order? Attempt to re-order. 3437 if( _head != loop->_head ) { 3438 // Find _next pointer to update 3439 IdealLoopTree **pp = &loop->_parent->_child; 3440 while( *pp != loop ) 3441 pp = &((*pp)->_next); 3442 // Find proper sibling to be next 3443 IdealLoopTree **nn = &loop->_next; 3444 while( (*nn) && (*nn)->_head != _head ) 3445 nn = &((*nn)->_next); 3446 3447 // Check for no match. 3448 if( !(*nn) ) { 3449 // Annoyingly, irreducible loops can pick different headers 3450 // after a major_progress operation, so the rest of the loop 3451 // tree cannot be matched. 3452 if (_irreducible && Compile::current()->major_progress()) return; 3453 assert( 0, "failed to match loop tree" ); 3454 } 3455 3456 // Move (*nn) to (*pp) 3457 IdealLoopTree *hit = *nn; 3458 *nn = hit->_next; 3459 hit->_next = loop; 3460 *pp = loop; 3461 loop = hit; 3462 // Now try again to verify 3463 } 3464 3465 assert( _head == loop->_head , "mismatched loop head" ); 3466 Node *tail = _tail; // Inline a non-updating version of 3467 while( !tail->in(0) ) // the 'tail()' call. 3468 tail = tail->in(1); 3469 assert( tail == loop->_tail, "mismatched loop tail" ); 3470 3471 // Counted loops that are guarded should be able to find their guards 3472 if( _head->is_CountedLoop() && _head->as_CountedLoop()->is_main_loop() ) { 3473 CountedLoopNode *cl = _head->as_CountedLoop(); 3474 Node *init = cl->init_trip(); 3475 Node *ctrl = cl->in(LoopNode::EntryControl); 3476 assert( ctrl->Opcode() == Op_IfTrue || ctrl->Opcode() == Op_IfFalse, "" ); 3477 Node *iff = ctrl->in(0); 3478 assert( iff->Opcode() == Op_If, "" ); 3479 Node *bol = iff->in(1); 3480 assert( bol->Opcode() == Op_Bool, "" ); 3481 Node *cmp = bol->in(1); 3482 assert( cmp->Opcode() == Op_CmpI, "" ); 3483 Node *add = cmp->in(1); 3484 Node *opaq; 3485 if( add->Opcode() == Op_Opaque1 ) { 3486 opaq = add; 3487 } else { 3488 assert( add->Opcode() == Op_AddI || add->Opcode() == Op_ConI , "" ); 3489 assert( add == init, "" ); 3490 opaq = cmp->in(2); 3491 } 3492 assert( opaq->Opcode() == Op_Opaque1, "" ); 3493 3494 } 3495 3496 if (_child != NULL) _child->verify_tree(loop->_child, this); 3497 if (_next != NULL) _next ->verify_tree(loop->_next, parent); 3498 // Innermost loops need to verify loop bodies, 3499 // but only if no 'major_progress' 3500 int fail = 0; 3501 if (!Compile::current()->major_progress() && _child == NULL) { 3502 for( uint i = 0; i < _body.size(); i++ ) { 3503 Node *n = _body.at(i); 3504 if (n->outcnt() == 0) continue; // Ignore dead 3505 uint j; 3506 for( j = 0; j < loop->_body.size(); j++ ) 3507 if( loop->_body.at(j) == n ) 3508 break; 3509 if( j == loop->_body.size() ) { // Not found in loop body 3510 // Last ditch effort to avoid assertion: Its possible that we 3511 // have some users (so outcnt not zero) but are still dead. 3512 // Try to find from root. 3513 if (Compile::current()->root()->find(n->_idx)) { 3514 fail++; 3515 tty->print("We have that verify does not: "); 3516 n->dump(); 3517 } 3518 } 3519 } 3520 for( uint i2 = 0; i2 < loop->_body.size(); i2++ ) { 3521 Node *n = loop->_body.at(i2); 3522 if (n->outcnt() == 0) continue; // Ignore dead 3523 uint j; 3524 for( j = 0; j < _body.size(); j++ ) 3525 if( _body.at(j) == n ) 3526 break; 3527 if( j == _body.size() ) { // Not found in loop body 3528 // Last ditch effort to avoid assertion: Its possible that we 3529 // have some users (so outcnt not zero) but are still dead. 3530 // Try to find from root. 3531 if (Compile::current()->root()->find(n->_idx)) { 3532 fail++; 3533 tty->print("Verify has that we do not: "); 3534 n->dump(); 3535 } 3536 } 3537 } 3538 assert( !fail, "loop body mismatch" ); 3539 } 3540 } 3541 3542 #endif 3543 3544 //------------------------------set_idom--------------------------------------- 3545 void PhaseIdealLoop::set_idom(Node* d, Node* n, uint dom_depth) { 3546 uint idx = d->_idx; 3547 if (idx >= _idom_size) { 3548 uint newsize = next_power_of_2(idx); 3549 _idom = REALLOC_RESOURCE_ARRAY( Node*, _idom,_idom_size,newsize); 3550 _dom_depth = REALLOC_RESOURCE_ARRAY( uint, _dom_depth,_idom_size,newsize); 3551 memset( _dom_depth + _idom_size, 0, (newsize - _idom_size) * sizeof(uint) ); 3552 _idom_size = newsize; 3553 } 3554 _idom[idx] = n; 3555 _dom_depth[idx] = dom_depth; 3556 } 3557 3558 //------------------------------recompute_dom_depth--------------------------------------- 3559 // The dominator tree is constructed with only parent pointers. 3560 // This recomputes the depth in the tree by first tagging all 3561 // nodes as "no depth yet" marker. The next pass then runs up 3562 // the dom tree from each node marked "no depth yet", and computes 3563 // the depth on the way back down. 3564 void PhaseIdealLoop::recompute_dom_depth() { 3565 uint no_depth_marker = C->unique(); 3566 uint i; 3567 // Initialize depth to "no depth yet" and realize all lazy updates 3568 for (i = 0; i < _idom_size; i++) { 3569 // Only indices with a _dom_depth has a Node* or NULL (otherwise uninitalized). 3570 if (_dom_depth[i] > 0 && _idom[i] != NULL) { 3571 _dom_depth[i] = no_depth_marker; 3572 3573 // heal _idom if it has a fwd mapping in _nodes 3574 if (_idom[i]->in(0) == NULL) { 3575 idom(i); 3576 } 3577 } 3578 } 3579 if (_dom_stk == NULL) { 3580 uint init_size = C->live_nodes() / 100; // Guess that 1/100 is a reasonable initial size. 3581 if (init_size < 10) init_size = 10; 3582 _dom_stk = new GrowableArray<uint>(init_size); 3583 } 3584 // Compute new depth for each node. 3585 for (i = 0; i < _idom_size; i++) { 3586 uint j = i; 3587 // Run up the dom tree to find a node with a depth 3588 while (_dom_depth[j] == no_depth_marker) { 3589 _dom_stk->push(j); 3590 j = _idom[j]->_idx; 3591 } 3592 // Compute the depth on the way back down this tree branch 3593 uint dd = _dom_depth[j] + 1; 3594 while (_dom_stk->length() > 0) { 3595 uint j = _dom_stk->pop(); 3596 _dom_depth[j] = dd; 3597 dd++; 3598 } 3599 } 3600 } 3601 3602 //------------------------------sort------------------------------------------- 3603 // Insert 'loop' into the existing loop tree. 'innermost' is a leaf of the 3604 // loop tree, not the root. 3605 IdealLoopTree *PhaseIdealLoop::sort( IdealLoopTree *loop, IdealLoopTree *innermost ) { 3606 if( !innermost ) return loop; // New innermost loop 3607 3608 int loop_preorder = get_preorder(loop->_head); // Cache pre-order number 3609 assert( loop_preorder, "not yet post-walked loop" ); 3610 IdealLoopTree **pp = &innermost; // Pointer to previous next-pointer 3611 IdealLoopTree *l = *pp; // Do I go before or after 'l'? 3612 3613 // Insert at start of list 3614 while( l ) { // Insertion sort based on pre-order 3615 if( l == loop ) return innermost; // Already on list! 3616 int l_preorder = get_preorder(l->_head); // Cache pre-order number 3617 assert( l_preorder, "not yet post-walked l" ); 3618 // Check header pre-order number to figure proper nesting 3619 if( loop_preorder > l_preorder ) 3620 break; // End of insertion 3621 // If headers tie (e.g., shared headers) check tail pre-order numbers. 3622 // Since I split shared headers, you'd think this could not happen. 3623 // BUT: I must first do the preorder numbering before I can discover I 3624 // have shared headers, so the split headers all get the same preorder 3625 // number as the RegionNode they split from. 3626 if( loop_preorder == l_preorder && 3627 get_preorder(loop->_tail) < get_preorder(l->_tail) ) 3628 break; // Also check for shared headers (same pre#) 3629 pp = &l->_parent; // Chain up list 3630 l = *pp; 3631 } 3632 // Link into list 3633 // Point predecessor to me 3634 *pp = loop; 3635 // Point me to successor 3636 IdealLoopTree *p = loop->_parent; 3637 loop->_parent = l; // Point me to successor 3638 if( p ) sort( p, innermost ); // Insert my parents into list as well 3639 return innermost; 3640 } 3641 3642 //------------------------------build_loop_tree-------------------------------- 3643 // I use a modified Vick/Tarjan algorithm. I need pre- and a post- visit 3644 // bits. The _nodes[] array is mapped by Node index and holds a NULL for 3645 // not-yet-pre-walked, pre-order # for pre-but-not-post-walked and holds the 3646 // tightest enclosing IdealLoopTree for post-walked. 3647 // 3648 // During my forward walk I do a short 1-layer lookahead to see if I can find 3649 // a loop backedge with that doesn't have any work on the backedge. This 3650 // helps me construct nested loops with shared headers better. 3651 // 3652 // Once I've done the forward recursion, I do the post-work. For each child 3653 // I check to see if there is a backedge. Backedges define a loop! I 3654 // insert an IdealLoopTree at the target of the backedge. 3655 // 3656 // During the post-work I also check to see if I have several children 3657 // belonging to different loops. If so, then this Node is a decision point 3658 // where control flow can choose to change loop nests. It is at this 3659 // decision point where I can figure out how loops are nested. At this 3660 // time I can properly order the different loop nests from my children. 3661 // Note that there may not be any backedges at the decision point! 3662 // 3663 // Since the decision point can be far removed from the backedges, I can't 3664 // order my loops at the time I discover them. Thus at the decision point 3665 // I need to inspect loop header pre-order numbers to properly nest my 3666 // loops. This means I need to sort my childrens' loops by pre-order. 3667 // The sort is of size number-of-control-children, which generally limits 3668 // it to size 2 (i.e., I just choose between my 2 target loops). 3669 void PhaseIdealLoop::build_loop_tree() { 3670 // Allocate stack of size C->live_nodes()/2 to avoid frequent realloc 3671 GrowableArray <Node *> bltstack(C->live_nodes() >> 1); 3672 Node *n = C->root(); 3673 bltstack.push(n); 3674 int pre_order = 1; 3675 int stack_size; 3676 3677 while ( ( stack_size = bltstack.length() ) != 0 ) { 3678 n = bltstack.top(); // Leave node on stack 3679 if ( !is_visited(n) ) { 3680 // ---- Pre-pass Work ---- 3681 // Pre-walked but not post-walked nodes need a pre_order number. 3682 3683 set_preorder_visited( n, pre_order ); // set as visited 3684 3685 // ---- Scan over children ---- 3686 // Scan first over control projections that lead to loop headers. 3687 // This helps us find inner-to-outer loops with shared headers better. 3688 3689 // Scan children's children for loop headers. 3690 for ( int i = n->outcnt() - 1; i >= 0; --i ) { 3691 Node* m = n->raw_out(i); // Child 3692 if( m->is_CFG() && !is_visited(m) ) { // Only for CFG children 3693 // Scan over children's children to find loop 3694 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) { 3695 Node* l = m->fast_out(j); 3696 if( is_visited(l) && // Been visited? 3697 !is_postvisited(l) && // But not post-visited 3698 get_preorder(l) < pre_order ) { // And smaller pre-order 3699 // Found! Scan the DFS down this path before doing other paths 3700 bltstack.push(m); 3701 break; 3702 } 3703 } 3704 } 3705 } 3706 pre_order++; 3707 } 3708 else if ( !is_postvisited(n) ) { 3709 // Note: build_loop_tree_impl() adds out edges on rare occasions, 3710 // such as com.sun.rsasign.am::a. 3711 // For non-recursive version, first, process current children. 3712 // On next iteration, check if additional children were added. 3713 for ( int k = n->outcnt() - 1; k >= 0; --k ) { 3714 Node* u = n->raw_out(k); 3715 if ( u->is_CFG() && !is_visited(u) ) { 3716 bltstack.push(u); 3717 } 3718 } 3719 if ( bltstack.length() == stack_size ) { 3720 // There were no additional children, post visit node now 3721 (void)bltstack.pop(); // Remove node from stack 3722 pre_order = build_loop_tree_impl( n, pre_order ); 3723 // Check for bailout 3724 if (C->failing()) { 3725 return; 3726 } 3727 // Check to grow _preorders[] array for the case when 3728 // build_loop_tree_impl() adds new nodes. 3729 check_grow_preorders(); 3730 } 3731 } 3732 else { 3733 (void)bltstack.pop(); // Remove post-visited node from stack 3734 } 3735 } 3736 } 3737 3738 //------------------------------build_loop_tree_impl--------------------------- 3739 int PhaseIdealLoop::build_loop_tree_impl( Node *n, int pre_order ) { 3740 // ---- Post-pass Work ---- 3741 // Pre-walked but not post-walked nodes need a pre_order number. 3742 3743 // Tightest enclosing loop for this Node 3744 IdealLoopTree *innermost = NULL; 3745 3746 // For all children, see if any edge is a backedge. If so, make a loop 3747 // for it. Then find the tightest enclosing loop for the self Node. 3748 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) { 3749 Node* m = n->fast_out(i); // Child 3750 if( n == m ) continue; // Ignore control self-cycles 3751 if( !m->is_CFG() ) continue;// Ignore non-CFG edges 3752 3753 IdealLoopTree *l; // Child's loop 3754 if( !is_postvisited(m) ) { // Child visited but not post-visited? 3755 // Found a backedge 3756 assert( get_preorder(m) < pre_order, "should be backedge" ); 3757 // Check for the RootNode, which is already a LoopNode and is allowed 3758 // to have multiple "backedges". 3759 if( m == C->root()) { // Found the root? 3760 l = _ltree_root; // Root is the outermost LoopNode 3761 } else { // Else found a nested loop 3762 // Insert a LoopNode to mark this loop. 3763 l = new IdealLoopTree(this, m, n); 3764 } // End of Else found a nested loop 3765 if( !has_loop(m) ) // If 'm' does not already have a loop set 3766 set_loop(m, l); // Set loop header to loop now 3767 3768 } else { // Else not a nested loop 3769 if( !_nodes[m->_idx] ) continue; // Dead code has no loop 3770 l = get_loop(m); // Get previously determined loop 3771 // If successor is header of a loop (nest), move up-loop till it 3772 // is a member of some outer enclosing loop. Since there are no 3773 // shared headers (I've split them already) I only need to go up 3774 // at most 1 level. 3775 while( l && l->_head == m ) // Successor heads loop? 3776 l = l->_parent; // Move up 1 for me 3777 // If this loop is not properly parented, then this loop 3778 // has no exit path out, i.e. its an infinite loop. 3779 if( !l ) { 3780 // Make loop "reachable" from root so the CFG is reachable. Basically 3781 // insert a bogus loop exit that is never taken. 'm', the loop head, 3782 // points to 'n', one (of possibly many) fall-in paths. There may be 3783 // many backedges as well. 3784 3785 // Here I set the loop to be the root loop. I could have, after 3786 // inserting a bogus loop exit, restarted the recursion and found my 3787 // new loop exit. This would make the infinite loop a first-class 3788 // loop and it would then get properly optimized. What's the use of 3789 // optimizing an infinite loop? 3790 l = _ltree_root; // Oops, found infinite loop 3791 3792 if (!_verify_only) { 3793 // Insert the NeverBranch between 'm' and it's control user. 3794 NeverBranchNode *iff = new NeverBranchNode( m ); 3795 _igvn.register_new_node_with_optimizer(iff); 3796 set_loop(iff, l); 3797 Node *if_t = new CProjNode( iff, 0 ); 3798 _igvn.register_new_node_with_optimizer(if_t); 3799 set_loop(if_t, l); 3800 3801 Node* cfg = NULL; // Find the One True Control User of m 3802 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) { 3803 Node* x = m->fast_out(j); 3804 if (x->is_CFG() && x != m && x != iff) 3805 { cfg = x; break; } 3806 } 3807 assert(cfg != NULL, "must find the control user of m"); 3808 uint k = 0; // Probably cfg->in(0) 3809 while( cfg->in(k) != m ) k++; // But check incase cfg is a Region 3810 cfg->set_req( k, if_t ); // Now point to NeverBranch 3811 _igvn._worklist.push(cfg); 3812 3813 // Now create the never-taken loop exit 3814 Node *if_f = new CProjNode( iff, 1 ); 3815 _igvn.register_new_node_with_optimizer(if_f); 3816 set_loop(if_f, l); 3817 // Find frame ptr for Halt. Relies on the optimizer 3818 // V-N'ing. Easier and quicker than searching through 3819 // the program structure. 3820 Node *frame = new ParmNode( C->start(), TypeFunc::FramePtr ); 3821 _igvn.register_new_node_with_optimizer(frame); 3822 // Halt & Catch Fire 3823 Node* halt = new HaltNode(if_f, frame, "never-taken loop exit reached"); 3824 _igvn.register_new_node_with_optimizer(halt); 3825 set_loop(halt, l); 3826 C->root()->add_req(halt); 3827 } 3828 set_loop(C->root(), _ltree_root); 3829 } 3830 } 3831 // Weeny check for irreducible. This child was already visited (this 3832 // IS the post-work phase). Is this child's loop header post-visited 3833 // as well? If so, then I found another entry into the loop. 3834 if (!_verify_only) { 3835 while( is_postvisited(l->_head) ) { 3836 // found irreducible 3837 l->_irreducible = 1; // = true 3838 l = l->_parent; 3839 _has_irreducible_loops = true; 3840 // Check for bad CFG here to prevent crash, and bailout of compile 3841 if (l == NULL) { 3842 C->record_method_not_compilable("unhandled CFG detected during loop optimization"); 3843 return pre_order; 3844 } 3845 } 3846 C->set_has_irreducible_loop(_has_irreducible_loops); 3847 } 3848 3849 // This Node might be a decision point for loops. It is only if 3850 // it's children belong to several different loops. The sort call 3851 // does a trivial amount of work if there is only 1 child or all 3852 // children belong to the same loop. If however, the children 3853 // belong to different loops, the sort call will properly set the 3854 // _parent pointers to show how the loops nest. 3855 // 3856 // In any case, it returns the tightest enclosing loop. 3857 innermost = sort( l, innermost ); 3858 } 3859 3860 // Def-use info will have some dead stuff; dead stuff will have no 3861 // loop decided on. 3862 3863 // Am I a loop header? If so fix up my parent's child and next ptrs. 3864 if( innermost && innermost->_head == n ) { 3865 assert( get_loop(n) == innermost, "" ); 3866 IdealLoopTree *p = innermost->_parent; 3867 IdealLoopTree *l = innermost; 3868 while( p && l->_head == n ) { 3869 l->_next = p->_child; // Put self on parents 'next child' 3870 p->_child = l; // Make self as first child of parent 3871 l = p; // Now walk up the parent chain 3872 p = l->_parent; 3873 } 3874 } else { 3875 // Note that it is possible for a LoopNode to reach here, if the 3876 // backedge has been made unreachable (hence the LoopNode no longer 3877 // denotes a Loop, and will eventually be removed). 3878 3879 // Record tightest enclosing loop for self. Mark as post-visited. 3880 set_loop(n, innermost); 3881 // Also record has_call flag early on 3882 if( innermost ) { 3883 if( n->is_Call() && !n->is_CallLeaf() && !n->is_macro() ) { 3884 // Do not count uncommon calls 3885 if( !n->is_CallStaticJava() || !n->as_CallStaticJava()->_name ) { 3886 Node *iff = n->in(0)->in(0); 3887 // No any calls for vectorized loops. 3888 if( UseSuperWord || !iff->is_If() || 3889 (n->in(0)->Opcode() == Op_IfFalse && 3890 (1.0 - iff->as_If()->_prob) >= 0.01) || 3891 (iff->as_If()->_prob >= 0.01) ) 3892 innermost->_has_call = 1; 3893 } 3894 } else if( n->is_Allocate() && n->as_Allocate()->_is_scalar_replaceable ) { 3895 // Disable loop optimizations if the loop has a scalar replaceable 3896 // allocation. This disabling may cause a potential performance lost 3897 // if the allocation is not eliminated for some reason. 3898 innermost->_allow_optimizations = false; 3899 innermost->_has_call = 1; // = true 3900 } else if (n->Opcode() == Op_SafePoint) { 3901 // Record all safepoints in this loop. 3902 if (innermost->_safepts == NULL) innermost->_safepts = new Node_List(); 3903 innermost->_safepts->push(n); 3904 } 3905 } 3906 } 3907 3908 // Flag as post-visited now 3909 set_postvisited(n); 3910 return pre_order; 3911 } 3912 3913 3914 //------------------------------build_loop_early------------------------------- 3915 // Put Data nodes into some loop nest, by setting the _nodes[]->loop mapping. 3916 // First pass computes the earliest controlling node possible. This is the 3917 // controlling input with the deepest dominating depth. 3918 void PhaseIdealLoop::build_loop_early( VectorSet &visited, Node_List &worklist, Node_Stack &nstack ) { 3919 while (worklist.size() != 0) { 3920 // Use local variables nstack_top_n & nstack_top_i to cache values 3921 // on nstack's top. 3922 Node *nstack_top_n = worklist.pop(); 3923 uint nstack_top_i = 0; 3924 //while_nstack_nonempty: 3925 while (true) { 3926 // Get parent node and next input's index from stack's top. 3927 Node *n = nstack_top_n; 3928 uint i = nstack_top_i; 3929 uint cnt = n->req(); // Count of inputs 3930 if (i == 0) { // Pre-process the node. 3931 if( has_node(n) && // Have either loop or control already? 3932 !has_ctrl(n) ) { // Have loop picked out already? 3933 // During "merge_many_backedges" we fold up several nested loops 3934 // into a single loop. This makes the members of the original 3935 // loop bodies pointing to dead loops; they need to move up 3936 // to the new UNION'd larger loop. I set the _head field of these 3937 // dead loops to NULL and the _parent field points to the owning 3938 // loop. Shades of UNION-FIND algorithm. 3939 IdealLoopTree *ilt; 3940 while( !(ilt = get_loop(n))->_head ) { 3941 // Normally I would use a set_loop here. But in this one special 3942 // case, it is legal (and expected) to change what loop a Node 3943 // belongs to. 3944 _nodes.map(n->_idx, (Node*)(ilt->_parent) ); 3945 } 3946 // Remove safepoints ONLY if I've already seen I don't need one. 3947 // (the old code here would yank a 2nd safepoint after seeing a 3948 // first one, even though the 1st did not dominate in the loop body 3949 // and thus could be avoided indefinitely) 3950 if( !_verify_only && !_verify_me && ilt->_has_sfpt && n->Opcode() == Op_SafePoint && 3951 is_deleteable_safept(n)) { 3952 Node *in = n->in(TypeFunc::Control); 3953 lazy_replace(n,in); // Pull safepoint now 3954 if (ilt->_safepts != NULL) { 3955 ilt->_safepts->yank(n); 3956 } 3957 // Carry on with the recursion "as if" we are walking 3958 // only the control input 3959 if( !visited.test_set( in->_idx ) ) { 3960 worklist.push(in); // Visit this guy later, using worklist 3961 } 3962 // Get next node from nstack: 3963 // - skip n's inputs processing by setting i > cnt; 3964 // - we also will not call set_early_ctrl(n) since 3965 // has_node(n) == true (see the condition above). 3966 i = cnt + 1; 3967 } 3968 } 3969 } // if (i == 0) 3970 3971 // Visit all inputs 3972 bool done = true; // Assume all n's inputs will be processed 3973 while (i < cnt) { 3974 Node *in = n->in(i); 3975 ++i; 3976 if (in == NULL) continue; 3977 if (in->pinned() && !in->is_CFG()) 3978 set_ctrl(in, in->in(0)); 3979 int is_visited = visited.test_set( in->_idx ); 3980 if (!has_node(in)) { // No controlling input yet? 3981 assert( !in->is_CFG(), "CFG Node with no controlling input?" ); 3982 assert( !is_visited, "visit only once" ); 3983 nstack.push(n, i); // Save parent node and next input's index. 3984 nstack_top_n = in; // Process current input now. 3985 nstack_top_i = 0; 3986 done = false; // Not all n's inputs processed. 3987 break; // continue while_nstack_nonempty; 3988 } else if (!is_visited) { 3989 // This guy has a location picked out for him, but has not yet 3990 // been visited. Happens to all CFG nodes, for instance. 3991 // Visit him using the worklist instead of recursion, to break 3992 // cycles. Since he has a location already we do not need to 3993 // find his location before proceeding with the current Node. 3994 worklist.push(in); // Visit this guy later, using worklist 3995 } 3996 } 3997 if (done) { 3998 // All of n's inputs have been processed, complete post-processing. 3999 4000 // Compute earliest point this Node can go. 4001 // CFG, Phi, pinned nodes already know their controlling input. 4002 if (!has_node(n)) { 4003 // Record earliest legal location 4004 set_early_ctrl( n ); 4005 } 4006 if (nstack.is_empty()) { 4007 // Finished all nodes on stack. 4008 // Process next node on the worklist. 4009 break; 4010 } 4011 // Get saved parent node and next input's index. 4012 nstack_top_n = nstack.node(); 4013 nstack_top_i = nstack.index(); 4014 nstack.pop(); 4015 } 4016 } // while (true) 4017 } 4018 } 4019 4020 //------------------------------dom_lca_internal-------------------------------- 4021 // Pair-wise LCA 4022 Node *PhaseIdealLoop::dom_lca_internal( Node *n1, Node *n2 ) const { 4023 if( !n1 ) return n2; // Handle NULL original LCA 4024 assert( n1->is_CFG(), "" ); 4025 assert( n2->is_CFG(), "" ); 4026 // find LCA of all uses 4027 uint d1 = dom_depth(n1); 4028 uint d2 = dom_depth(n2); 4029 while (n1 != n2) { 4030 if (d1 > d2) { 4031 n1 = idom(n1); 4032 d1 = dom_depth(n1); 4033 } else if (d1 < d2) { 4034 n2 = idom(n2); 4035 d2 = dom_depth(n2); 4036 } else { 4037 // Here d1 == d2. Due to edits of the dominator-tree, sections 4038 // of the tree might have the same depth. These sections have 4039 // to be searched more carefully. 4040 4041 // Scan up all the n1's with equal depth, looking for n2. 4042 Node *t1 = idom(n1); 4043 while (dom_depth(t1) == d1) { 4044 if (t1 == n2) return n2; 4045 t1 = idom(t1); 4046 } 4047 // Scan up all the n2's with equal depth, looking for n1. 4048 Node *t2 = idom(n2); 4049 while (dom_depth(t2) == d2) { 4050 if (t2 == n1) return n1; 4051 t2 = idom(t2); 4052 } 4053 // Move up to a new dominator-depth value as well as up the dom-tree. 4054 n1 = t1; 4055 n2 = t2; 4056 d1 = dom_depth(n1); 4057 d2 = dom_depth(n2); 4058 } 4059 } 4060 return n1; 4061 } 4062 4063 //------------------------------compute_idom----------------------------------- 4064 // Locally compute IDOM using dom_lca call. Correct only if the incoming 4065 // IDOMs are correct. 4066 Node *PhaseIdealLoop::compute_idom( Node *region ) const { 4067 assert( region->is_Region(), "" ); 4068 Node *LCA = NULL; 4069 for( uint i = 1; i < region->req(); i++ ) { 4070 if( region->in(i) != C->top() ) 4071 LCA = dom_lca( LCA, region->in(i) ); 4072 } 4073 return LCA; 4074 } 4075 4076 bool PhaseIdealLoop::verify_dominance(Node* n, Node* use, Node* LCA, Node* early) { 4077 bool had_error = false; 4078 #ifdef ASSERT 4079 if (early != C->root()) { 4080 // Make sure that there's a dominance path from LCA to early 4081 Node* d = LCA; 4082 while (d != early) { 4083 if (d == C->root()) { 4084 dump_bad_graph("Bad graph detected in compute_lca_of_uses", n, early, LCA); 4085 tty->print_cr("*** Use %d isn't dominated by def %d ***", use->_idx, n->_idx); 4086 had_error = true; 4087 break; 4088 } 4089 d = idom(d); 4090 } 4091 } 4092 #endif 4093 return had_error; 4094 } 4095 4096 4097 Node* PhaseIdealLoop::compute_lca_of_uses(Node* n, Node* early, bool verify) { 4098 // Compute LCA over list of uses 4099 bool had_error = false; 4100 Node *LCA = NULL; 4101 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax && LCA != early; i++) { 4102 Node* c = n->fast_out(i); 4103 if (_nodes[c->_idx] == NULL) 4104 continue; // Skip the occasional dead node 4105 if( c->is_Phi() ) { // For Phis, we must land above on the path 4106 for( uint j=1; j<c->req(); j++ ) {// For all inputs 4107 if( c->in(j) == n ) { // Found matching input? 4108 Node *use = c->in(0)->in(j); 4109 if (_verify_only && use->is_top()) continue; 4110 LCA = dom_lca_for_get_late_ctrl( LCA, use, n ); 4111 if (verify) had_error = verify_dominance(n, use, LCA, early) || had_error; 4112 } 4113 } 4114 } else { 4115 // For CFG data-users, use is in the block just prior 4116 Node *use = has_ctrl(c) ? get_ctrl(c) : c->in(0); 4117 LCA = dom_lca_for_get_late_ctrl( LCA, use, n ); 4118 if (verify) had_error = verify_dominance(n, use, LCA, early) || had_error; 4119 } 4120 } 4121 assert(!had_error, "bad dominance"); 4122 return LCA; 4123 } 4124 4125 // Check the shape of the graph at the loop entry. In some cases, 4126 // the shape of the graph does not match the shape outlined below. 4127 // That is caused by the Opaque1 node "protecting" the shape of 4128 // the graph being removed by, for example, the IGVN performed 4129 // in PhaseIdealLoop::build_and_optimize(). 4130 // 4131 // After the Opaque1 node has been removed, optimizations (e.g., split-if, 4132 // loop unswitching, and IGVN, or a combination of them) can freely change 4133 // the graph's shape. As a result, the graph shape outlined below cannot 4134 // be guaranteed anymore. 4135 bool PhaseIdealLoop::is_canonical_loop_entry(CountedLoopNode* cl) { 4136 if (!cl->is_main_loop() && !cl->is_post_loop()) { 4137 return false; 4138 } 4139 Node* ctrl = cl->skip_predicates(); 4140 4141 if (ctrl == NULL || (!ctrl->is_IfTrue() && !ctrl->is_IfFalse())) { 4142 return false; 4143 } 4144 Node* iffm = ctrl->in(0); 4145 if (iffm == NULL || !iffm->is_If()) { 4146 return false; 4147 } 4148 Node* bolzm = iffm->in(1); 4149 if (bolzm == NULL || !bolzm->is_Bool()) { 4150 return false; 4151 } 4152 Node* cmpzm = bolzm->in(1); 4153 if (cmpzm == NULL || !cmpzm->is_Cmp()) { 4154 return false; 4155 } 4156 // compares can get conditionally flipped 4157 bool found_opaque = false; 4158 for (uint i = 1; i < cmpzm->req(); i++) { 4159 Node* opnd = cmpzm->in(i); 4160 if (opnd && opnd->Opcode() == Op_Opaque1) { 4161 found_opaque = true; 4162 break; 4163 } 4164 } 4165 if (!found_opaque) { 4166 return false; 4167 } 4168 return true; 4169 } 4170 4171 //------------------------------get_late_ctrl---------------------------------- 4172 // Compute latest legal control. 4173 Node *PhaseIdealLoop::get_late_ctrl( Node *n, Node *early ) { 4174 assert(early != NULL, "early control should not be NULL"); 4175 4176 Node* LCA = compute_lca_of_uses(n, early); 4177 #ifdef ASSERT 4178 if (LCA == C->root() && LCA != early) { 4179 // def doesn't dominate uses so print some useful debugging output 4180 compute_lca_of_uses(n, early, true); 4181 } 4182 #endif 4183 4184 // if this is a load, check for anti-dependent stores 4185 // We use a conservative algorithm to identify potential interfering 4186 // instructions and for rescheduling the load. The users of the memory 4187 // input of this load are examined. Any use which is not a load and is 4188 // dominated by early is considered a potentially interfering store. 4189 // This can produce false positives. 4190 if (n->is_Load() && LCA != early) { 4191 int load_alias_idx = C->get_alias_index(n->adr_type()); 4192 if (C->alias_type(load_alias_idx)->is_rewritable()) { 4193 4194 Node_List worklist; 4195 4196 Node *mem = n->in(MemNode::Memory); 4197 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) { 4198 Node* s = mem->fast_out(i); 4199 worklist.push(s); 4200 } 4201 while(worklist.size() != 0 && LCA != early) { 4202 Node* s = worklist.pop(); 4203 if (s->is_Load() || s->Opcode() == Op_SafePoint || 4204 (s->is_CallStaticJava() && s->as_CallStaticJava()->uncommon_trap_request() != 0)) { 4205 continue; 4206 } else if (s->is_MergeMem()) { 4207 for (DUIterator_Fast imax, i = s->fast_outs(imax); i < imax; i++) { 4208 Node* s1 = s->fast_out(i); 4209 worklist.push(s1); 4210 } 4211 } else { 4212 Node *sctrl = has_ctrl(s) ? get_ctrl(s) : s->in(0); 4213 const TypePtr* adr_type = s->adr_type(); 4214 if (s->is_ArrayCopy()) { 4215 // Copy to known instance needs destination type to test for aliasing 4216 const TypePtr* dest_type = s->as_ArrayCopy()->_dest_type; 4217 if (dest_type != TypeOopPtr::BOTTOM) { 4218 adr_type = dest_type; 4219 } 4220 } 4221 assert(sctrl != NULL || !s->is_reachable_from_root(), "must have control"); 4222 if (sctrl != NULL && !sctrl->is_top() && C->can_alias(adr_type, load_alias_idx) && is_dominator(early, sctrl)) { 4223 LCA = dom_lca_for_get_late_ctrl(LCA, sctrl, n); 4224 } 4225 } 4226 } 4227 } 4228 } 4229 4230 assert(LCA == find_non_split_ctrl(LCA), "unexpected late control"); 4231 return LCA; 4232 } 4233 4234 // true if CFG node d dominates CFG node n 4235 bool PhaseIdealLoop::is_dominator(Node *d, Node *n) { 4236 if (d == n) 4237 return true; 4238 assert(d->is_CFG() && n->is_CFG(), "must have CFG nodes"); 4239 uint dd = dom_depth(d); 4240 while (dom_depth(n) >= dd) { 4241 if (n == d) 4242 return true; 4243 n = idom(n); 4244 } 4245 return false; 4246 } 4247 4248 //------------------------------dom_lca_for_get_late_ctrl_internal------------- 4249 // Pair-wise LCA with tags. 4250 // Tag each index with the node 'tag' currently being processed 4251 // before advancing up the dominator chain using idom(). 4252 // Later calls that find a match to 'tag' know that this path has already 4253 // been considered in the current LCA (which is input 'n1' by convention). 4254 // Since get_late_ctrl() is only called once for each node, the tag array 4255 // does not need to be cleared between calls to get_late_ctrl(). 4256 // Algorithm trades a larger constant factor for better asymptotic behavior 4257 // 4258 Node *PhaseIdealLoop::dom_lca_for_get_late_ctrl_internal( Node *n1, Node *n2, Node *tag ) { 4259 uint d1 = dom_depth(n1); 4260 uint d2 = dom_depth(n2); 4261 4262 do { 4263 if (d1 > d2) { 4264 // current lca is deeper than n2 4265 _dom_lca_tags.map(n1->_idx, tag); 4266 n1 = idom(n1); 4267 d1 = dom_depth(n1); 4268 } else if (d1 < d2) { 4269 // n2 is deeper than current lca 4270 Node *memo = _dom_lca_tags[n2->_idx]; 4271 if( memo == tag ) { 4272 return n1; // Return the current LCA 4273 } 4274 _dom_lca_tags.map(n2->_idx, tag); 4275 n2 = idom(n2); 4276 d2 = dom_depth(n2); 4277 } else { 4278 // Here d1 == d2. Due to edits of the dominator-tree, sections 4279 // of the tree might have the same depth. These sections have 4280 // to be searched more carefully. 4281 4282 // Scan up all the n1's with equal depth, looking for n2. 4283 _dom_lca_tags.map(n1->_idx, tag); 4284 Node *t1 = idom(n1); 4285 while (dom_depth(t1) == d1) { 4286 if (t1 == n2) return n2; 4287 _dom_lca_tags.map(t1->_idx, tag); 4288 t1 = idom(t1); 4289 } 4290 // Scan up all the n2's with equal depth, looking for n1. 4291 _dom_lca_tags.map(n2->_idx, tag); 4292 Node *t2 = idom(n2); 4293 while (dom_depth(t2) == d2) { 4294 if (t2 == n1) return n1; 4295 _dom_lca_tags.map(t2->_idx, tag); 4296 t2 = idom(t2); 4297 } 4298 // Move up to a new dominator-depth value as well as up the dom-tree. 4299 n1 = t1; 4300 n2 = t2; 4301 d1 = dom_depth(n1); 4302 d2 = dom_depth(n2); 4303 } 4304 } while (n1 != n2); 4305 return n1; 4306 } 4307 4308 //------------------------------init_dom_lca_tags------------------------------ 4309 // Tag could be a node's integer index, 32bits instead of 64bits in some cases 4310 // Intended use does not involve any growth for the array, so it could 4311 // be of fixed size. 4312 void PhaseIdealLoop::init_dom_lca_tags() { 4313 uint limit = C->unique() + 1; 4314 _dom_lca_tags.map( limit, NULL ); 4315 #ifdef ASSERT 4316 for( uint i = 0; i < limit; ++i ) { 4317 assert(_dom_lca_tags[i] == NULL, "Must be distinct from each node pointer"); 4318 } 4319 #endif // ASSERT 4320 } 4321 4322 //------------------------------clear_dom_lca_tags------------------------------ 4323 // Tag could be a node's integer index, 32bits instead of 64bits in some cases 4324 // Intended use does not involve any growth for the array, so it could 4325 // be of fixed size. 4326 void PhaseIdealLoop::clear_dom_lca_tags() { 4327 uint limit = C->unique() + 1; 4328 _dom_lca_tags.map( limit, NULL ); 4329 _dom_lca_tags.clear(); 4330 #ifdef ASSERT 4331 for( uint i = 0; i < limit; ++i ) { 4332 assert(_dom_lca_tags[i] == NULL, "Must be distinct from each node pointer"); 4333 } 4334 #endif // ASSERT 4335 } 4336 4337 //------------------------------build_loop_late-------------------------------- 4338 // Put Data nodes into some loop nest, by setting the _nodes[]->loop mapping. 4339 // Second pass finds latest legal placement, and ideal loop placement. 4340 void PhaseIdealLoop::build_loop_late( VectorSet &visited, Node_List &worklist, Node_Stack &nstack ) { 4341 while (worklist.size() != 0) { 4342 Node *n = worklist.pop(); 4343 // Only visit once 4344 if (visited.test_set(n->_idx)) continue; 4345 uint cnt = n->outcnt(); 4346 uint i = 0; 4347 while (true) { 4348 assert( _nodes[n->_idx], "no dead nodes" ); 4349 // Visit all children 4350 if (i < cnt) { 4351 Node* use = n->raw_out(i); 4352 ++i; 4353 // Check for dead uses. Aggressively prune such junk. It might be 4354 // dead in the global sense, but still have local uses so I cannot 4355 // easily call 'remove_dead_node'. 4356 if( _nodes[use->_idx] != NULL || use->is_top() ) { // Not dead? 4357 // Due to cycles, we might not hit the same fixed point in the verify 4358 // pass as we do in the regular pass. Instead, visit such phis as 4359 // simple uses of the loop head. 4360 if( use->in(0) && (use->is_CFG() || use->is_Phi()) ) { 4361 if( !visited.test(use->_idx) ) 4362 worklist.push(use); 4363 } else if( !visited.test_set(use->_idx) ) { 4364 nstack.push(n, i); // Save parent and next use's index. 4365 n = use; // Process all children of current use. 4366 cnt = use->outcnt(); 4367 i = 0; 4368 } 4369 } else { 4370 // Do not visit around the backedge of loops via data edges. 4371 // push dead code onto a worklist 4372 _deadlist.push(use); 4373 } 4374 } else { 4375 // All of n's children have been processed, complete post-processing. 4376 build_loop_late_post(n); 4377 if (nstack.is_empty()) { 4378 // Finished all nodes on stack. 4379 // Process next node on the worklist. 4380 break; 4381 } 4382 // Get saved parent node and next use's index. Visit the rest of uses. 4383 n = nstack.node(); 4384 cnt = n->outcnt(); 4385 i = nstack.index(); 4386 nstack.pop(); 4387 } 4388 } 4389 } 4390 } 4391 4392 // Verify that no data node is scheduled in the outer loop of a strip 4393 // mined loop. 4394 void PhaseIdealLoop::verify_strip_mined_scheduling(Node *n, Node* least) { 4395 #ifdef ASSERT 4396 if (get_loop(least)->_nest == 0) { 4397 return; 4398 } 4399 IdealLoopTree* loop = get_loop(least); 4400 Node* head = loop->_head; 4401 if (head->is_OuterStripMinedLoop() && 4402 // Verification can't be applied to fully built strip mined loops 4403 head->as_Loop()->outer_loop_end()->in(1)->find_int_con(-1) == 0) { 4404 Node* sfpt = head->as_Loop()->outer_safepoint(); 4405 ResourceMark rm; 4406 Unique_Node_List wq; 4407 wq.push(sfpt); 4408 for (uint i = 0; i < wq.size(); i++) { 4409 Node *m = wq.at(i); 4410 for (uint i = 1; i < m->req(); i++) { 4411 Node* nn = m->in(i); 4412 if (nn == n) { 4413 return; 4414 } 4415 if (nn != NULL && has_ctrl(nn) && get_loop(get_ctrl(nn)) == loop) { 4416 wq.push(nn); 4417 } 4418 } 4419 } 4420 ShouldNotReachHere(); 4421 } 4422 #endif 4423 } 4424 4425 4426 //------------------------------build_loop_late_post--------------------------- 4427 // Put Data nodes into some loop nest, by setting the _nodes[]->loop mapping. 4428 // Second pass finds latest legal placement, and ideal loop placement. 4429 void PhaseIdealLoop::build_loop_late_post(Node *n) { 4430 build_loop_late_post_work(n, true); 4431 } 4432 4433 void PhaseIdealLoop::build_loop_late_post_work(Node *n, bool pinned) { 4434 4435 if (n->req() == 2 && (n->Opcode() == Op_ConvI2L || n->Opcode() == Op_CastII) && !C->major_progress() && !_verify_only) { 4436 _igvn._worklist.push(n); // Maybe we'll normalize it, if no more loops. 4437 } 4438 4439 #ifdef ASSERT 4440 if (_verify_only && !n->is_CFG()) { 4441 // Check def-use domination. 4442 compute_lca_of_uses(n, get_ctrl(n), true /* verify */); 4443 } 4444 #endif 4445 4446 // CFG and pinned nodes already handled 4447 if( n->in(0) ) { 4448 if( n->in(0)->is_top() ) return; // Dead? 4449 4450 // We'd like +VerifyLoopOptimizations to not believe that Mod's/Loads 4451 // _must_ be pinned (they have to observe their control edge of course). 4452 // Unlike Stores (which modify an unallocable resource, the memory 4453 // state), Mods/Loads can float around. So free them up. 4454 switch( n->Opcode() ) { 4455 case Op_DivI: 4456 case Op_DivF: 4457 case Op_DivD: 4458 case Op_ModI: 4459 case Op_ModF: 4460 case Op_ModD: 4461 case Op_LoadB: // Same with Loads; they can sink 4462 case Op_LoadUB: // during loop optimizations. 4463 case Op_LoadUS: 4464 case Op_LoadD: 4465 case Op_LoadF: 4466 case Op_LoadI: 4467 case Op_LoadKlass: 4468 case Op_LoadNKlass: 4469 case Op_LoadL: 4470 case Op_LoadS: 4471 case Op_LoadP: 4472 case Op_LoadN: 4473 case Op_LoadRange: 4474 case Op_LoadD_unaligned: 4475 case Op_LoadL_unaligned: 4476 case Op_StrComp: // Does a bunch of load-like effects 4477 case Op_StrEquals: 4478 case Op_StrIndexOf: 4479 case Op_StrIndexOfChar: 4480 case Op_AryEq: 4481 case Op_HasNegatives: 4482 pinned = false; 4483 } 4484 if (n->is_CMove()) { 4485 pinned = false; 4486 } 4487 if( pinned ) { 4488 IdealLoopTree *chosen_loop = get_loop(n->is_CFG() ? n : get_ctrl(n)); 4489 if( !chosen_loop->_child ) // Inner loop? 4490 chosen_loop->_body.push(n); // Collect inner loops 4491 return; 4492 } 4493 } else { // No slot zero 4494 if( n->is_CFG() ) { // CFG with no slot 0 is dead 4495 _nodes.map(n->_idx,0); // No block setting, it's globally dead 4496 return; 4497 } 4498 assert(!n->is_CFG() || n->outcnt() == 0, ""); 4499 } 4500 4501 // Do I have a "safe range" I can select over? 4502 Node *early = get_ctrl(n);// Early location already computed 4503 4504 // Compute latest point this Node can go 4505 Node *LCA = get_late_ctrl( n, early ); 4506 // LCA is NULL due to uses being dead 4507 if( LCA == NULL ) { 4508 #ifdef ASSERT 4509 for (DUIterator i1 = n->outs(); n->has_out(i1); i1++) { 4510 assert( _nodes[n->out(i1)->_idx] == NULL, "all uses must also be dead"); 4511 } 4512 #endif 4513 _nodes.map(n->_idx, 0); // This node is useless 4514 _deadlist.push(n); 4515 return; 4516 } 4517 assert(LCA != NULL && !LCA->is_top(), "no dead nodes"); 4518 4519 Node *legal = LCA; // Walk 'legal' up the IDOM chain 4520 Node *least = legal; // Best legal position so far 4521 while( early != legal ) { // While not at earliest legal 4522 #ifdef ASSERT 4523 if (legal->is_Start() && !early->is_Root()) { 4524 // Bad graph. Print idom path and fail. 4525 dump_bad_graph("Bad graph detected in build_loop_late", n, early, LCA); 4526 assert(false, "Bad graph detected in build_loop_late"); 4527 } 4528 #endif 4529 // Find least loop nesting depth 4530 legal = idom(legal); // Bump up the IDOM tree 4531 // Check for lower nesting depth 4532 if( get_loop(legal)->_nest < get_loop(least)->_nest ) 4533 least = legal; 4534 } 4535 assert(early == legal || legal != C->root(), "bad dominance of inputs"); 4536 4537 // Try not to place code on a loop entry projection 4538 // which can inhibit range check elimination. 4539 if (least != early) { 4540 Node* ctrl_out = least->unique_ctrl_out(); 4541 if (ctrl_out && ctrl_out->is_Loop() && 4542 least == ctrl_out->in(LoopNode::EntryControl)) { 4543 // Move the node above predicates as far up as possible so a 4544 // following pass of loop predication doesn't hoist a predicate 4545 // that depends on it above that node. 4546 Node* new_ctrl = least; 4547 for (;;) { 4548 if (!new_ctrl->is_Proj()) { 4549 break; 4550 } 4551 CallStaticJavaNode* call = new_ctrl->as_Proj()->is_uncommon_trap_if_pattern(Deoptimization::Reason_none); 4552 if (call == NULL) { 4553 break; 4554 } 4555 int req = call->uncommon_trap_request(); 4556 Deoptimization::DeoptReason trap_reason = Deoptimization::trap_request_reason(req); 4557 if (trap_reason != Deoptimization::Reason_loop_limit_check && 4558 trap_reason != Deoptimization::Reason_predicate && 4559 trap_reason != Deoptimization::Reason_profile_predicate) { 4560 break; 4561 } 4562 Node* c = new_ctrl->in(0)->in(0); 4563 if (is_dominator(c, early) && c != early) { 4564 break; 4565 } 4566 new_ctrl = c; 4567 } 4568 least = new_ctrl; 4569 } 4570 } 4571 4572 #ifdef ASSERT 4573 // If verifying, verify that 'verify_me' has a legal location 4574 // and choose it as our location. 4575 if( _verify_me ) { 4576 Node *v_ctrl = _verify_me->get_ctrl_no_update(n); 4577 Node *legal = LCA; 4578 while( early != legal ) { // While not at earliest legal 4579 if( legal == v_ctrl ) break; // Check for prior good location 4580 legal = idom(legal) ;// Bump up the IDOM tree 4581 } 4582 // Check for prior good location 4583 if( legal == v_ctrl ) least = legal; // Keep prior if found 4584 } 4585 #endif 4586 4587 // Assign discovered "here or above" point 4588 least = find_non_split_ctrl(least); 4589 verify_strip_mined_scheduling(n, least); 4590 set_ctrl(n, least); 4591 4592 // Collect inner loop bodies 4593 IdealLoopTree *chosen_loop = get_loop(least); 4594 if( !chosen_loop->_child ) // Inner loop? 4595 chosen_loop->_body.push(n);// Collect inner loops 4596 } 4597 4598 #ifdef ASSERT 4599 void PhaseIdealLoop::dump_bad_graph(const char* msg, Node* n, Node* early, Node* LCA) { 4600 tty->print_cr("%s", msg); 4601 tty->print("n: "); n->dump(); 4602 tty->print("early(n): "); early->dump(); 4603 if (n->in(0) != NULL && !n->in(0)->is_top() && 4604 n->in(0) != early && !n->in(0)->is_Root()) { 4605 tty->print("n->in(0): "); n->in(0)->dump(); 4606 } 4607 for (uint i = 1; i < n->req(); i++) { 4608 Node* in1 = n->in(i); 4609 if (in1 != NULL && in1 != n && !in1->is_top()) { 4610 tty->print("n->in(%d): ", i); in1->dump(); 4611 Node* in1_early = get_ctrl(in1); 4612 tty->print("early(n->in(%d)): ", i); in1_early->dump(); 4613 if (in1->in(0) != NULL && !in1->in(0)->is_top() && 4614 in1->in(0) != in1_early && !in1->in(0)->is_Root()) { 4615 tty->print("n->in(%d)->in(0): ", i); in1->in(0)->dump(); 4616 } 4617 for (uint j = 1; j < in1->req(); j++) { 4618 Node* in2 = in1->in(j); 4619 if (in2 != NULL && in2 != n && in2 != in1 && !in2->is_top()) { 4620 tty->print("n->in(%d)->in(%d): ", i, j); in2->dump(); 4621 Node* in2_early = get_ctrl(in2); 4622 tty->print("early(n->in(%d)->in(%d)): ", i, j); in2_early->dump(); 4623 if (in2->in(0) != NULL && !in2->in(0)->is_top() && 4624 in2->in(0) != in2_early && !in2->in(0)->is_Root()) { 4625 tty->print("n->in(%d)->in(%d)->in(0): ", i, j); in2->in(0)->dump(); 4626 } 4627 } 4628 } 4629 } 4630 } 4631 tty->cr(); 4632 tty->print("LCA(n): "); LCA->dump(); 4633 for (uint i = 0; i < n->outcnt(); i++) { 4634 Node* u1 = n->raw_out(i); 4635 if (u1 == n) 4636 continue; 4637 tty->print("n->out(%d): ", i); u1->dump(); 4638 if (u1->is_CFG()) { 4639 for (uint j = 0; j < u1->outcnt(); j++) { 4640 Node* u2 = u1->raw_out(j); 4641 if (u2 != u1 && u2 != n && u2->is_CFG()) { 4642 tty->print("n->out(%d)->out(%d): ", i, j); u2->dump(); 4643 } 4644 } 4645 } else { 4646 Node* u1_later = get_ctrl(u1); 4647 tty->print("later(n->out(%d)): ", i); u1_later->dump(); 4648 if (u1->in(0) != NULL && !u1->in(0)->is_top() && 4649 u1->in(0) != u1_later && !u1->in(0)->is_Root()) { 4650 tty->print("n->out(%d)->in(0): ", i); u1->in(0)->dump(); 4651 } 4652 for (uint j = 0; j < u1->outcnt(); j++) { 4653 Node* u2 = u1->raw_out(j); 4654 if (u2 == n || u2 == u1) 4655 continue; 4656 tty->print("n->out(%d)->out(%d): ", i, j); u2->dump(); 4657 if (!u2->is_CFG()) { 4658 Node* u2_later = get_ctrl(u2); 4659 tty->print("later(n->out(%d)->out(%d)): ", i, j); u2_later->dump(); 4660 if (u2->in(0) != NULL && !u2->in(0)->is_top() && 4661 u2->in(0) != u2_later && !u2->in(0)->is_Root()) { 4662 tty->print("n->out(%d)->in(0): ", i); u2->in(0)->dump(); 4663 } 4664 } 4665 } 4666 } 4667 } 4668 tty->cr(); 4669 int ct = 0; 4670 Node *dbg_legal = LCA; 4671 while(!dbg_legal->is_Start() && ct < 100) { 4672 tty->print("idom[%d] ",ct); dbg_legal->dump(); 4673 ct++; 4674 dbg_legal = idom(dbg_legal); 4675 } 4676 tty->cr(); 4677 } 4678 #endif 4679 4680 #ifndef PRODUCT 4681 //------------------------------dump------------------------------------------- 4682 void PhaseIdealLoop::dump() const { 4683 ResourceMark rm; 4684 Arena* arena = Thread::current()->resource_area(); 4685 Node_Stack stack(arena, C->live_nodes() >> 2); 4686 Node_List rpo_list; 4687 VectorSet visited(arena); 4688 visited.set(C->top()->_idx); 4689 rpo(C->root(), stack, visited, rpo_list); 4690 // Dump root loop indexed by last element in PO order 4691 dump(_ltree_root, rpo_list.size(), rpo_list); 4692 } 4693 4694 void PhaseIdealLoop::dump(IdealLoopTree* loop, uint idx, Node_List &rpo_list) const { 4695 loop->dump_head(); 4696 4697 // Now scan for CFG nodes in the same loop 4698 for (uint j = idx; j > 0; j--) { 4699 Node* n = rpo_list[j-1]; 4700 if (!_nodes[n->_idx]) // Skip dead nodes 4701 continue; 4702 4703 if (get_loop(n) != loop) { // Wrong loop nest 4704 if (get_loop(n)->_head == n && // Found nested loop? 4705 get_loop(n)->_parent == loop) 4706 dump(get_loop(n), rpo_list.size(), rpo_list); // Print it nested-ly 4707 continue; 4708 } 4709 4710 // Dump controlling node 4711 tty->sp(2 * loop->_nest); 4712 tty->print("C"); 4713 if (n == C->root()) { 4714 n->dump(); 4715 } else { 4716 Node* cached_idom = idom_no_update(n); 4717 Node* computed_idom = n->in(0); 4718 if (n->is_Region()) { 4719 computed_idom = compute_idom(n); 4720 // computed_idom() will return n->in(0) when idom(n) is an IfNode (or 4721 // any MultiBranch ctrl node), so apply a similar transform to 4722 // the cached idom returned from idom_no_update. 4723 cached_idom = find_non_split_ctrl(cached_idom); 4724 } 4725 tty->print(" ID:%d", computed_idom->_idx); 4726 n->dump(); 4727 if (cached_idom != computed_idom) { 4728 tty->print_cr("*** BROKEN IDOM! Computed as: %d, cached as: %d", 4729 computed_idom->_idx, cached_idom->_idx); 4730 } 4731 } 4732 // Dump nodes it controls 4733 for (uint k = 0; k < _nodes.Size(); k++) { 4734 // (k < C->unique() && get_ctrl(find(k)) == n) 4735 if (k < C->unique() && _nodes[k] == (Node*)((intptr_t)n + 1)) { 4736 Node* m = C->root()->find(k); 4737 if (m && m->outcnt() > 0) { 4738 if (!(has_ctrl(m) && get_ctrl_no_update(m) == n)) { 4739 tty->print_cr("*** BROKEN CTRL ACCESSOR! _nodes[k] is %p, ctrl is %p", 4740 _nodes[k], has_ctrl(m) ? get_ctrl_no_update(m) : NULL); 4741 } 4742 tty->sp(2 * loop->_nest + 1); 4743 m->dump(); 4744 } 4745 } 4746 } 4747 } 4748 } 4749 #endif 4750 4751 // Collect a R-P-O for the whole CFG. 4752 // Result list is in post-order (scan backwards for RPO) 4753 void PhaseIdealLoop::rpo(Node* start, Node_Stack &stk, VectorSet &visited, Node_List &rpo_list) const { 4754 stk.push(start, 0); 4755 visited.set(start->_idx); 4756 4757 while (stk.is_nonempty()) { 4758 Node* m = stk.node(); 4759 uint idx = stk.index(); 4760 if (idx < m->outcnt()) { 4761 stk.set_index(idx + 1); 4762 Node* n = m->raw_out(idx); 4763 if (n->is_CFG() && !visited.test_set(n->_idx)) { 4764 stk.push(n, 0); 4765 } 4766 } else { 4767 rpo_list.push(m); 4768 stk.pop(); 4769 } 4770 } 4771 } 4772 4773 4774 //============================================================================= 4775 //------------------------------LoopTreeIterator------------------------------- 4776 4777 // Advance to next loop tree using a preorder, left-to-right traversal. 4778 void LoopTreeIterator::next() { 4779 assert(!done(), "must not be done."); 4780 if (_curnt->_child != NULL) { 4781 _curnt = _curnt->_child; 4782 } else if (_curnt->_next != NULL) { 4783 _curnt = _curnt->_next; 4784 } else { 4785 while (_curnt != _root && _curnt->_next == NULL) { 4786 _curnt = _curnt->_parent; 4787 } 4788 if (_curnt == _root) { 4789 _curnt = NULL; 4790 assert(done(), "must be done."); 4791 } else { 4792 assert(_curnt->_next != NULL, "must be more to do"); 4793 _curnt = _curnt->_next; 4794 } 4795 } 4796 }