1 /* 2 * Copyright (c) 1997, 2025, 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 "gc/shared/barrierSet.hpp" 26 #include "gc/shared/c2/barrierSetC2.hpp" 27 #include "memory/allocation.inline.hpp" 28 #include "memory/resourceArea.hpp" 29 #include "oops/objArrayKlass.hpp" 30 #include "opto/addnode.hpp" 31 #include "opto/castnode.hpp" 32 #include "opto/cfgnode.hpp" 33 #include "opto/connode.hpp" 34 #include "opto/convertnode.hpp" 35 #include "opto/inlinetypenode.hpp" 36 #include "opto/loopnode.hpp" 37 #include "opto/machnode.hpp" 38 #include "opto/movenode.hpp" 39 #include "opto/narrowptrnode.hpp" 40 #include "opto/mulnode.hpp" 41 #include "opto/phaseX.hpp" 42 #include "opto/regalloc.hpp" 43 #include "opto/regmask.hpp" 44 #include "opto/runtime.hpp" 45 #include "opto/subnode.hpp" 46 #include "opto/vectornode.hpp" 47 #include "utilities/vmError.hpp" 48 49 // Portions of code courtesy of Clifford Click 50 51 // Optimization - Graph Style 52 53 //============================================================================= 54 //------------------------------Value------------------------------------------ 55 // Compute the type of the RegionNode. 56 const Type* RegionNode::Value(PhaseGVN* phase) const { 57 for( uint i=1; i<req(); ++i ) { // For all paths in 58 Node *n = in(i); // Get Control source 59 if( !n ) continue; // Missing inputs are TOP 60 if( phase->type(n) == Type::CONTROL ) 61 return Type::CONTROL; 62 } 63 return Type::TOP; // All paths dead? Then so are we 64 } 65 66 //------------------------------Identity--------------------------------------- 67 // Check for Region being Identity. 68 Node* RegionNode::Identity(PhaseGVN* phase) { 69 // Cannot have Region be an identity, even if it has only 1 input. 70 // Phi users cannot have their Region input folded away for them, 71 // since they need to select the proper data input 72 return this; 73 } 74 75 //------------------------------merge_region----------------------------------- 76 // If a Region flows into a Region, merge into one big happy merge. This is 77 // hard to do if there is stuff that has to happen 78 static Node *merge_region(RegionNode *region, PhaseGVN *phase) { 79 if( region->Opcode() != Op_Region ) // Do not do to LoopNodes 80 return nullptr; 81 Node *progress = nullptr; // Progress flag 82 PhaseIterGVN *igvn = phase->is_IterGVN(); 83 84 uint rreq = region->req(); 85 for( uint i = 1; i < rreq; i++ ) { 86 Node *r = region->in(i); 87 if( r && r->Opcode() == Op_Region && // Found a region? 88 r->in(0) == r && // Not already collapsed? 89 r != region && // Avoid stupid situations 90 r->outcnt() == 2 ) { // Self user and 'region' user only? 91 assert(!r->as_Region()->has_phi(), "no phi users"); 92 if( !progress ) { // No progress 93 if (region->has_phi()) { 94 return nullptr; // Only flatten if no Phi users 95 // igvn->hash_delete( phi ); 96 } 97 igvn->hash_delete( region ); 98 progress = region; // Making progress 99 } 100 igvn->hash_delete( r ); 101 102 // Append inputs to 'r' onto 'region' 103 for( uint j = 1; j < r->req(); j++ ) { 104 // Move an input from 'r' to 'region' 105 region->add_req(r->in(j)); 106 r->set_req(j, phase->C->top()); 107 // Update phis of 'region' 108 //for( uint k = 0; k < max; k++ ) { 109 // Node *phi = region->out(k); 110 // if( phi->is_Phi() ) { 111 // phi->add_req(phi->in(i)); 112 // } 113 //} 114 115 rreq++; // One more input to Region 116 } // Found a region to merge into Region 117 igvn->_worklist.push(r); 118 // Clobber pointer to the now dead 'r' 119 region->set_req(i, phase->C->top()); 120 } 121 } 122 123 return progress; 124 } 125 126 127 128 //--------------------------------has_phi-------------------------------------- 129 // Helper function: Return any PhiNode that uses this region or null 130 PhiNode* RegionNode::has_phi() const { 131 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) { 132 Node* phi = fast_out(i); 133 if (phi->is_Phi()) { // Check for Phi users 134 assert(phi->in(0) == (Node*)this, "phi uses region only via in(0)"); 135 return phi->as_Phi(); // this one is good enough 136 } 137 } 138 139 return nullptr; 140 } 141 142 143 //-----------------------------has_unique_phi---------------------------------- 144 // Helper function: Return the only PhiNode that uses this region or null 145 PhiNode* RegionNode::has_unique_phi() const { 146 // Check that only one use is a Phi 147 PhiNode* only_phi = nullptr; 148 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) { 149 Node* phi = fast_out(i); 150 if (phi->is_Phi()) { // Check for Phi users 151 assert(phi->in(0) == (Node*)this, "phi uses region only via in(0)"); 152 if (only_phi == nullptr) { 153 only_phi = phi->as_Phi(); 154 } else { 155 return nullptr; // multiple phis 156 } 157 } 158 } 159 160 return only_phi; 161 } 162 163 164 //------------------------------check_phi_clipping----------------------------- 165 // Helper function for RegionNode's identification of FP clipping 166 // Check inputs to the Phi 167 static bool check_phi_clipping( PhiNode *phi, ConNode * &min, uint &min_idx, ConNode * &max, uint &max_idx, Node * &val, uint &val_idx ) { 168 min = nullptr; 169 max = nullptr; 170 val = nullptr; 171 min_idx = 0; 172 max_idx = 0; 173 val_idx = 0; 174 uint phi_max = phi->req(); 175 if( phi_max == 4 ) { 176 for( uint j = 1; j < phi_max; ++j ) { 177 Node *n = phi->in(j); 178 int opcode = n->Opcode(); 179 switch( opcode ) { 180 case Op_ConI: 181 { 182 if( min == nullptr ) { 183 min = n->Opcode() == Op_ConI ? (ConNode*)n : nullptr; 184 min_idx = j; 185 } else { 186 max = n->Opcode() == Op_ConI ? (ConNode*)n : nullptr; 187 max_idx = j; 188 if( min->get_int() > max->get_int() ) { 189 // Swap min and max 190 ConNode *temp; 191 uint temp_idx; 192 temp = min; min = max; max = temp; 193 temp_idx = min_idx; min_idx = max_idx; max_idx = temp_idx; 194 } 195 } 196 } 197 break; 198 default: 199 { 200 val = n; 201 val_idx = j; 202 } 203 break; 204 } 205 } 206 } 207 return ( min && max && val && (min->get_int() <= 0) && (max->get_int() >=0) ); 208 } 209 210 211 //------------------------------check_if_clipping------------------------------ 212 // Helper function for RegionNode's identification of FP clipping 213 // Check that inputs to Region come from two IfNodes, 214 // 215 // If 216 // False True 217 // If | 218 // False True | 219 // | | | 220 // RegionNode_inputs 221 // 222 static bool check_if_clipping( const RegionNode *region, IfNode * &bot_if, IfNode * &top_if ) { 223 top_if = nullptr; 224 bot_if = nullptr; 225 226 // Check control structure above RegionNode for (if ( if ) ) 227 Node *in1 = region->in(1); 228 Node *in2 = region->in(2); 229 Node *in3 = region->in(3); 230 // Check that all inputs are projections 231 if( in1->is_Proj() && in2->is_Proj() && in3->is_Proj() ) { 232 Node *in10 = in1->in(0); 233 Node *in20 = in2->in(0); 234 Node *in30 = in3->in(0); 235 // Check that #1 and #2 are ifTrue and ifFalse from same If 236 if( in10 != nullptr && in10->is_If() && 237 in20 != nullptr && in20->is_If() && 238 in30 != nullptr && in30->is_If() && in10 == in20 && 239 (in1->Opcode() != in2->Opcode()) ) { 240 Node *in100 = in10->in(0); 241 Node *in1000 = (in100 != nullptr && in100->is_Proj()) ? in100->in(0) : nullptr; 242 // Check that control for in10 comes from other branch of IF from in3 243 if( in1000 != nullptr && in1000->is_If() && 244 in30 == in1000 && (in3->Opcode() != in100->Opcode()) ) { 245 // Control pattern checks 246 top_if = (IfNode*)in1000; 247 bot_if = (IfNode*)in10; 248 } 249 } 250 } 251 252 return (top_if != nullptr); 253 } 254 255 256 //------------------------------check_convf2i_clipping------------------------- 257 // Helper function for RegionNode's identification of FP clipping 258 // Verify that the value input to the phi comes from "ConvF2I; LShift; RShift" 259 static bool check_convf2i_clipping( PhiNode *phi, uint idx, ConvF2INode * &convf2i, Node *min, Node *max) { 260 convf2i = nullptr; 261 262 // Check for the RShiftNode 263 Node *rshift = phi->in(idx); 264 assert( rshift, "Previous checks ensure phi input is present"); 265 if( rshift->Opcode() != Op_RShiftI ) { return false; } 266 267 // Check for the LShiftNode 268 Node *lshift = rshift->in(1); 269 assert( lshift, "Previous checks ensure phi input is present"); 270 if( lshift->Opcode() != Op_LShiftI ) { return false; } 271 272 // Check for the ConvF2INode 273 Node *conv = lshift->in(1); 274 if( conv->Opcode() != Op_ConvF2I ) { return false; } 275 276 // Check that shift amounts are only to get sign bits set after F2I 277 jint max_cutoff = max->get_int(); 278 jint min_cutoff = min->get_int(); 279 jint left_shift = lshift->in(2)->get_int(); 280 jint right_shift = rshift->in(2)->get_int(); 281 jint max_post_shift = nth_bit(BitsPerJavaInteger - left_shift - 1); 282 if( left_shift != right_shift || 283 0 > left_shift || left_shift >= BitsPerJavaInteger || 284 max_post_shift < max_cutoff || 285 max_post_shift < -min_cutoff ) { 286 // Shifts are necessary but current transformation eliminates them 287 return false; 288 } 289 290 // OK to return the result of ConvF2I without shifting 291 convf2i = (ConvF2INode*)conv; 292 return true; 293 } 294 295 296 //------------------------------check_compare_clipping------------------------- 297 // Helper function for RegionNode's identification of FP clipping 298 static bool check_compare_clipping( bool less_than, IfNode *iff, ConNode *limit, Node * & input ) { 299 Node *i1 = iff->in(1); 300 if ( !i1->is_Bool() ) { return false; } 301 BoolNode *bool1 = i1->as_Bool(); 302 if( less_than && bool1->_test._test != BoolTest::le ) { return false; } 303 else if( !less_than && bool1->_test._test != BoolTest::lt ) { return false; } 304 const Node *cmpF = bool1->in(1); 305 if( cmpF->Opcode() != Op_CmpF ) { return false; } 306 // Test that the float value being compared against 307 // is equivalent to the int value used as a limit 308 Node *nodef = cmpF->in(2); 309 if( nodef->Opcode() != Op_ConF ) { return false; } 310 jfloat conf = nodef->getf(); 311 jint coni = limit->get_int(); 312 if( ((int)conf) != coni ) { return false; } 313 input = cmpF->in(1); 314 return true; 315 } 316 317 //------------------------------is_unreachable_region-------------------------- 318 // Check if the RegionNode is part of an unsafe loop and unreachable from root. 319 bool RegionNode::is_unreachable_region(const PhaseGVN* phase) { 320 Node* top = phase->C->top(); 321 assert(req() == 2 || (req() == 3 && in(1) != nullptr && in(2) == top), "sanity check arguments"); 322 if (_is_unreachable_region) { 323 // Return cached result from previous evaluation which should still be valid 324 assert(is_unreachable_from_root(phase), "walk the graph again and check if its indeed unreachable"); 325 return true; 326 } 327 328 // First, cut the simple case of fallthrough region when NONE of 329 // region's phis references itself directly or through a data node. 330 if (is_possible_unsafe_loop(phase)) { 331 // If we have a possible unsafe loop, check if the region node is actually unreachable from root. 332 if (is_unreachable_from_root(phase)) { 333 _is_unreachable_region = true; 334 return true; 335 } 336 } 337 return false; 338 } 339 340 bool RegionNode::is_possible_unsafe_loop(const PhaseGVN* phase) const { 341 uint max = outcnt(); 342 uint i; 343 for (i = 0; i < max; i++) { 344 Node* n = raw_out(i); 345 if (n != nullptr && n->is_Phi()) { 346 PhiNode* phi = n->as_Phi(); 347 assert(phi->in(0) == this, "sanity check phi"); 348 if (phi->outcnt() == 0) { 349 continue; // Safe case - no loops 350 } 351 if (phi->outcnt() == 1) { 352 Node* u = phi->raw_out(0); 353 // Skip if only one use is an other Phi or Call or Uncommon trap. 354 // It is safe to consider this case as fallthrough. 355 if (u != nullptr && (u->is_Phi() || u->is_CFG())) { 356 continue; 357 } 358 } 359 // Check when phi references itself directly or through an other node. 360 if (phi->as_Phi()->simple_data_loop_check(phi->in(1)) >= PhiNode::Unsafe) { 361 break; // Found possible unsafe data loop. 362 } 363 } 364 } 365 if (i >= max) { 366 return false; // An unsafe case was NOT found - don't need graph walk. 367 } 368 return true; 369 } 370 371 bool RegionNode::is_unreachable_from_root(const PhaseGVN* phase) const { 372 ResourceMark rm; 373 Node_List nstack; 374 VectorSet visited; 375 376 // Mark all control nodes reachable from root outputs 377 Node* n = (Node*)phase->C->root(); 378 nstack.push(n); 379 visited.set(n->_idx); 380 while (nstack.size() != 0) { 381 n = nstack.pop(); 382 uint max = n->outcnt(); 383 for (uint i = 0; i < max; i++) { 384 Node* m = n->raw_out(i); 385 if (m != nullptr && m->is_CFG()) { 386 if (m == this) { 387 return false; // We reached the Region node - it is not dead. 388 } 389 if (!visited.test_set(m->_idx)) 390 nstack.push(m); 391 } 392 } 393 } 394 return true; // The Region node is unreachable - it is dead. 395 } 396 397 #ifdef ASSERT 398 // Is this region in an infinite subgraph? 399 // (no path to root except through false NeverBranch exit) 400 bool RegionNode::is_in_infinite_subgraph() { 401 ResourceMark rm; 402 Unique_Node_List worklist; 403 worklist.push(this); 404 return RegionNode::are_all_nodes_in_infinite_subgraph(worklist); 405 } 406 407 // Are all nodes in worklist in infinite subgraph? 408 // (no path to root except through false NeverBranch exit) 409 // worklist is directly used for the traversal 410 bool RegionNode::are_all_nodes_in_infinite_subgraph(Unique_Node_List& worklist) { 411 // BFS traversal down the CFG, except through NeverBranch exits 412 for (uint i = 0; i < worklist.size(); ++i) { 413 Node* n = worklist.at(i); 414 assert(n->is_CFG(), "only traverse CFG"); 415 if (n->is_Root()) { 416 // Found root -> there was an exit! 417 return false; 418 } else if (n->is_NeverBranch()) { 419 // Only follow the loop-internal projection, not the NeverBranch exit 420 ProjNode* proj = n->as_NeverBranch()->proj_out_or_null(0); 421 assert(proj != nullptr, "must find loop-internal projection of NeverBranch"); 422 worklist.push(proj); 423 } else { 424 // Traverse all CFG outputs 425 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) { 426 Node* use = n->fast_out(i); 427 if (use->is_CFG()) { 428 worklist.push(use); 429 } 430 } 431 } 432 } 433 // No exit found for any loop -> all are infinite 434 return true; 435 } 436 #endif //ASSERT 437 438 void RegionNode::set_loop_status(RegionNode::LoopStatus status) { 439 assert(loop_status() == RegionNode::LoopStatus::NeverIrreducibleEntry, "why set our status again?"); 440 assert(status != RegionNode::LoopStatus::MaybeIrreducibleEntry || !is_Loop(), "LoopNode is never irreducible entry."); 441 _loop_status = status; 442 } 443 444 // A Region can only be an irreducible entry if: 445 // - It is marked as "maybe irreducible entry". Any other loop status would guarantee 446 // that it is never an irreducible loop entry. 447 // - And it is not a LoopNode, those are guaranteed to be reducible loop entries. 448 bool RegionNode::can_be_irreducible_entry() const { 449 return loop_status() == RegionNode::LoopStatus::MaybeIrreducibleEntry && 450 !is_Loop(); 451 } 452 453 void RegionNode::try_clean_mem_phis(PhaseIterGVN* igvn) { 454 // Incremental inlining + PhaseStringOpts sometimes produce: 455 // 456 // cmpP with 1 top input 457 // | 458 // If 459 // / \ 460 // IfFalse IfTrue /- Some Node 461 // \ / / / 462 // Region / /-MergeMem 463 // \---Phi 464 // 465 // 466 // It's expected by PhaseStringOpts that the Region goes away and is 467 // replaced by If's control input but because there's still a Phi, 468 // the Region stays in the graph. The top input from the cmpP is 469 // propagated forward and a subgraph that is useful goes away. The 470 // code in PhiNode::try_clean_memory_phi() replaces the Phi with the 471 // MergeMem in order to remove the Region if its last phi dies. 472 473 if (!is_diamond()) { 474 return; 475 } 476 477 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) { 478 Node* phi = fast_out(i); 479 if (phi->is_Phi() && phi->as_Phi()->try_clean_memory_phi(igvn)) { 480 --i; 481 --imax; 482 } 483 } 484 } 485 486 // Does this region merge a simple diamond formed by a proper IfNode? 487 // 488 // Cmp 489 // / 490 // ctrl Bool 491 // \ / 492 // IfNode 493 // / \ 494 // IfFalse IfTrue 495 // \ / 496 // Region 497 bool RegionNode::is_diamond() const { 498 if (req() != 3) { 499 return false; 500 } 501 502 Node* left_path = in(1); 503 Node* right_path = in(2); 504 if (left_path == nullptr || right_path == nullptr) { 505 return false; 506 } 507 Node* diamond_if = left_path->in(0); 508 if (diamond_if == nullptr || !diamond_if->is_If() || diamond_if != right_path->in(0)) { 509 // Not an IfNode merging a diamond or TOP. 510 return false; 511 } 512 513 // Check for a proper bool/cmp 514 const Node* bol = diamond_if->in(1); 515 if (!bol->is_Bool()) { 516 return false; 517 } 518 const Node* cmp = bol->in(1); 519 if (!cmp->is_Cmp()) { 520 return false; 521 } 522 return true; 523 } 524 525 //------------------------------Ideal------------------------------------------ 526 // Return a node which is more "ideal" than the current node. Must preserve 527 // the CFG, but we can still strip out dead paths. 528 Node *RegionNode::Ideal(PhaseGVN *phase, bool can_reshape) { 529 if( !can_reshape && !in(0) ) return nullptr; // Already degraded to a Copy 530 assert(!in(0) || !in(0)->is_Root(), "not a specially hidden merge"); 531 532 // Check for RegionNode with no Phi users and both inputs come from either 533 // arm of the same IF. If found, then the control-flow split is useless. 534 bool has_phis = false; 535 if (can_reshape) { // Need DU info to check for Phi users 536 try_clean_mem_phis(phase->is_IterGVN()); 537 has_phis = (has_phi() != nullptr); // Cache result 538 539 if (!has_phis) { // No Phi users? Nothing merging? 540 for (uint i = 1; i < req()-1; i++) { 541 Node *if1 = in(i); 542 if( !if1 ) continue; 543 Node *iff = if1->in(0); 544 if( !iff || !iff->is_If() ) continue; 545 for( uint j=i+1; j<req(); j++ ) { 546 if( in(j) && in(j)->in(0) == iff && 547 if1->Opcode() != in(j)->Opcode() ) { 548 // Add the IF Projections to the worklist. They (and the IF itself) 549 // will be eliminated if dead. 550 phase->is_IterGVN()->add_users_to_worklist(iff); 551 set_req(i, iff->in(0));// Skip around the useless IF diamond 552 set_req(j, nullptr); 553 return this; // Record progress 554 } 555 } 556 } 557 } 558 } 559 560 // Remove TOP or null input paths. If only 1 input path remains, this Region 561 // degrades to a copy. 562 bool add_to_worklist = true; 563 bool modified = false; 564 int cnt = 0; // Count of values merging 565 DEBUG_ONLY( int cnt_orig = req(); ) // Save original inputs count 566 DEBUG_ONLY( uint outcnt_orig = outcnt(); ) 567 int del_it = 0; // The last input path we delete 568 bool found_top = false; // irreducible loops need to check reachability if we find TOP 569 // For all inputs... 570 for( uint i=1; i<req(); ++i ){// For all paths in 571 Node *n = in(i); // Get the input 572 if( n != nullptr ) { 573 // Remove useless control copy inputs 574 if( n->is_Region() && n->as_Region()->is_copy() ) { 575 set_req(i, n->nonnull_req()); 576 modified = true; 577 i--; 578 continue; 579 } 580 if( n->is_Proj() ) { // Remove useless rethrows 581 Node *call = n->in(0); 582 if (call->is_Call() && call->as_Call()->entry_point() == OptoRuntime::rethrow_stub()) { 583 set_req(i, call->in(0)); 584 modified = true; 585 i--; 586 continue; 587 } 588 } 589 if( phase->type(n) == Type::TOP ) { 590 set_req_X(i, nullptr, phase); // Ignore TOP inputs 591 modified = true; 592 found_top = true; 593 i--; 594 continue; 595 } 596 cnt++; // One more value merging 597 } else if (can_reshape) { // Else found dead path with DU info 598 PhaseIterGVN *igvn = phase->is_IterGVN(); 599 del_req(i); // Yank path from self 600 del_it = i; 601 602 for (DUIterator_Fast jmax, j = fast_outs(jmax); j < jmax; j++) { 603 Node* use = fast_out(j); 604 605 if (use->req() != req() && use->is_Phi()) { 606 assert(use->in(0) == this, "unexpected control input"); 607 igvn->hash_delete(use); // Yank from hash before hacking edges 608 use->set_req_X(i, nullptr, igvn);// Correct DU info 609 use->del_req(i); // Yank path from Phis 610 } 611 } 612 613 if (add_to_worklist) { 614 igvn->add_users_to_worklist(this); 615 add_to_worklist = false; 616 } 617 618 i--; 619 } 620 } 621 622 assert(outcnt() == outcnt_orig, "not expect to remove any use"); 623 624 if (can_reshape && found_top && loop_status() == RegionNode::LoopStatus::MaybeIrreducibleEntry) { 625 // Is it a dead irreducible loop? 626 // If an irreducible loop loses one of the multiple entries 627 // that went into the loop head, or any secondary entries, 628 // we need to verify if the irreducible loop is still reachable, 629 // as the special logic in is_unreachable_region only works 630 // for reducible loops. 631 if (is_unreachable_from_root(phase)) { 632 // The irreducible loop is dead - must remove it 633 PhaseIterGVN* igvn = phase->is_IterGVN(); 634 remove_unreachable_subgraph(igvn); 635 return nullptr; 636 } 637 } else if (can_reshape && cnt == 1) { 638 // Is it dead loop? 639 // If it is LoopNopde it had 2 (+1 itself) inputs and 640 // one of them was cut. The loop is dead if it was EntryContol. 641 // Loop node may have only one input because entry path 642 // is removed in PhaseIdealLoop::Dominators(). 643 assert(!this->is_Loop() || cnt_orig <= 3, "Loop node should have 3 or less inputs"); 644 if ((this->is_Loop() && (del_it == LoopNode::EntryControl || 645 (del_it == 0 && is_unreachable_region(phase)))) || 646 (!this->is_Loop() && has_phis && is_unreachable_region(phase))) { 647 PhaseIterGVN* igvn = phase->is_IterGVN(); 648 remove_unreachable_subgraph(igvn); 649 return nullptr; 650 } 651 } 652 653 if( cnt <= 1 ) { // Only 1 path in? 654 set_req(0, nullptr); // Null control input for region copy 655 if( cnt == 0 && !can_reshape) { // Parse phase - leave the node as it is. 656 // No inputs or all inputs are null. 657 return nullptr; 658 } else if (can_reshape) { // Optimization phase - remove the node 659 PhaseIterGVN *igvn = phase->is_IterGVN(); 660 // Strip mined (inner) loop is going away, remove outer loop. 661 if (is_CountedLoop() && 662 as_Loop()->is_strip_mined()) { 663 Node* outer_sfpt = as_CountedLoop()->outer_safepoint(); 664 Node* outer_out = as_CountedLoop()->outer_loop_exit(); 665 if (outer_sfpt != nullptr && outer_out != nullptr) { 666 Node* in = outer_sfpt->in(0); 667 igvn->replace_node(outer_out, in); 668 LoopNode* outer = as_CountedLoop()->outer_loop(); 669 igvn->replace_input_of(outer, LoopNode::LoopBackControl, igvn->C->top()); 670 } 671 } 672 if (is_CountedLoop()) { 673 Node* opaq = as_CountedLoop()->is_canonical_loop_entry(); 674 if (opaq != nullptr) { 675 // This is not a loop anymore. No need to keep the Opaque1 node on the test that guards the loop as it won't be 676 // subject to further loop opts. 677 assert(opaq->Opcode() == Op_OpaqueZeroTripGuard, ""); 678 igvn->replace_node(opaq, opaq->in(1)); 679 } 680 } 681 Node *parent_ctrl; 682 if( cnt == 0 ) { 683 assert( req() == 1, "no inputs expected" ); 684 // During IGVN phase such region will be subsumed by TOP node 685 // so region's phis will have TOP as control node. 686 // Kill phis here to avoid it. 687 // Also set other user's input to top. 688 parent_ctrl = phase->C->top(); 689 } else { 690 // The fallthrough case since we already checked dead loops above. 691 parent_ctrl = in(1); 692 assert(parent_ctrl != nullptr, "Region is a copy of some non-null control"); 693 assert(parent_ctrl != this, "Close dead loop"); 694 } 695 if (add_to_worklist) { 696 igvn->add_users_to_worklist(this); // Check for further allowed opts 697 } 698 for (DUIterator_Last imin, i = last_outs(imin); i >= imin; --i) { 699 Node* n = last_out(i); 700 igvn->hash_delete(n); // Remove from worklist before modifying edges 701 if (n->outcnt() == 0) { 702 int uses_found = n->replace_edge(this, phase->C->top(), igvn); 703 if (uses_found > 1) { // (--i) done at the end of the loop. 704 i -= (uses_found - 1); 705 } 706 continue; 707 } 708 if( n->is_Phi() ) { // Collapse all Phis 709 // Eagerly replace phis to avoid regionless phis. 710 Node* in; 711 if( cnt == 0 ) { 712 assert( n->req() == 1, "No data inputs expected" ); 713 in = parent_ctrl; // replaced by top 714 } else { 715 assert( n->req() == 2 && n->in(1) != nullptr, "Only one data input expected" ); 716 in = n->in(1); // replaced by unique input 717 if( n->as_Phi()->is_unsafe_data_reference(in) ) 718 in = phase->C->top(); // replaced by top 719 } 720 igvn->replace_node(n, in); 721 } 722 else if( n->is_Region() ) { // Update all incoming edges 723 assert(n != this, "Must be removed from DefUse edges"); 724 int uses_found = n->replace_edge(this, parent_ctrl, igvn); 725 if (uses_found > 1) { // (--i) done at the end of the loop. 726 i -= (uses_found - 1); 727 } 728 } 729 else { 730 assert(n->in(0) == this, "Expect RegionNode to be control parent"); 731 n->set_req(0, parent_ctrl); 732 } 733 #ifdef ASSERT 734 for( uint k=0; k < n->req(); k++ ) { 735 assert(n->in(k) != this, "All uses of RegionNode should be gone"); 736 } 737 #endif 738 } 739 // Remove the RegionNode itself from DefUse info 740 igvn->remove_dead_node(this); 741 return nullptr; 742 } 743 return this; // Record progress 744 } 745 746 747 // If a Region flows into a Region, merge into one big happy merge. 748 if (can_reshape) { 749 Node *m = merge_region(this, phase); 750 if (m != nullptr) return m; 751 } 752 753 // Check if this region is the root of a clipping idiom on floats 754 if( ConvertFloat2IntClipping && can_reshape && req() == 4 ) { 755 // Check that only one use is a Phi and that it simplifies to two constants + 756 PhiNode* phi = has_unique_phi(); 757 if (phi != nullptr) { // One Phi user 758 // Check inputs to the Phi 759 ConNode *min; 760 ConNode *max; 761 Node *val; 762 uint min_idx; 763 uint max_idx; 764 uint val_idx; 765 if( check_phi_clipping( phi, min, min_idx, max, max_idx, val, val_idx ) ) { 766 IfNode *top_if; 767 IfNode *bot_if; 768 if( check_if_clipping( this, bot_if, top_if ) ) { 769 // Control pattern checks, now verify compares 770 Node *top_in = nullptr; // value being compared against 771 Node *bot_in = nullptr; 772 if( check_compare_clipping( true, bot_if, min, bot_in ) && 773 check_compare_clipping( false, top_if, max, top_in ) ) { 774 if( bot_in == top_in ) { 775 PhaseIterGVN *gvn = phase->is_IterGVN(); 776 assert( gvn != nullptr, "Only had DefUse info in IterGVN"); 777 // Only remaining check is that bot_in == top_in == (Phi's val + mods) 778 779 // Check for the ConvF2INode 780 ConvF2INode *convf2i; 781 if( check_convf2i_clipping( phi, val_idx, convf2i, min, max ) && 782 convf2i->in(1) == bot_in ) { 783 // Matched pattern, including LShiftI; RShiftI, replace with integer compares 784 // max test 785 Node *cmp = gvn->register_new_node_with_optimizer(new CmpINode( convf2i, min )); 786 Node *boo = gvn->register_new_node_with_optimizer(new BoolNode( cmp, BoolTest::lt )); 787 IfNode *iff = (IfNode*)gvn->register_new_node_with_optimizer(new IfNode( top_if->in(0), boo, PROB_UNLIKELY_MAG(5), top_if->_fcnt )); 788 Node *if_min= gvn->register_new_node_with_optimizer(new IfTrueNode (iff)); 789 Node *ifF = gvn->register_new_node_with_optimizer(new IfFalseNode(iff)); 790 // min test 791 cmp = gvn->register_new_node_with_optimizer(new CmpINode( convf2i, max )); 792 boo = gvn->register_new_node_with_optimizer(new BoolNode( cmp, BoolTest::gt )); 793 iff = (IfNode*)gvn->register_new_node_with_optimizer(new IfNode( ifF, boo, PROB_UNLIKELY_MAG(5), bot_if->_fcnt )); 794 Node *if_max= gvn->register_new_node_with_optimizer(new IfTrueNode (iff)); 795 ifF = gvn->register_new_node_with_optimizer(new IfFalseNode(iff)); 796 // update input edges to region node 797 set_req_X( min_idx, if_min, gvn ); 798 set_req_X( max_idx, if_max, gvn ); 799 set_req_X( val_idx, ifF, gvn ); 800 // remove unnecessary 'LShiftI; RShiftI' idiom 801 gvn->hash_delete(phi); 802 phi->set_req_X( val_idx, convf2i, gvn ); 803 gvn->hash_find_insert(phi); 804 // Return transformed region node 805 return this; 806 } 807 } 808 } 809 } 810 } 811 } 812 } 813 814 if (can_reshape) { 815 modified |= optimize_trichotomy(phase->is_IterGVN()); 816 } 817 818 return modified ? this : nullptr; 819 } 820 821 //--------------------------remove_unreachable_subgraph---------------------- 822 // This region and therefore all nodes on the input control path(s) are unreachable 823 // from root. To avoid incomplete removal of unreachable subgraphs, walk up the CFG 824 // and aggressively replace all nodes by top. 825 // If a control node "def" with a single control output "use" has its single output 826 // "use" replaced with top, then "use" removes itself. This has the consequence that 827 // when we visit "use", it already has all inputs removed. They are lost and we cannot 828 // traverse them. This is why we fist find all unreachable nodes, and then remove 829 // them in a second step. 830 void RegionNode::remove_unreachable_subgraph(PhaseIterGVN* igvn) { 831 Node* top = igvn->C->top(); 832 ResourceMark rm; 833 Unique_Node_List unreachable; // visit each only once 834 unreachable.push(this); 835 // Recursively find all control inputs. 836 for (uint i = 0; i < unreachable.size(); i++) { 837 Node* n = unreachable.at(i); 838 for (uint i = 0; i < n->req(); ++i) { 839 Node* m = n->in(i); 840 assert(m == nullptr || !m->is_Root(), "Should be unreachable from root"); 841 if (m != nullptr && m->is_CFG()) { 842 unreachable.push(m); 843 } 844 } 845 } 846 // Remove all unreachable nodes. 847 for (uint i = 0; i < unreachable.size(); i++) { 848 Node* n = unreachable.at(i); 849 if (n->is_Region()) { 850 // Eagerly replace phis with top to avoid regionless phis. 851 n->set_req(0, nullptr); 852 bool progress = true; 853 uint max = n->outcnt(); 854 DUIterator j; 855 while (progress) { 856 progress = false; 857 for (j = n->outs(); n->has_out(j); j++) { 858 Node* u = n->out(j); 859 if (u->is_Phi()) { 860 igvn->replace_node(u, top); 861 if (max != n->outcnt()) { 862 progress = true; 863 j = n->refresh_out_pos(j); 864 max = n->outcnt(); 865 } 866 } 867 } 868 } 869 } 870 igvn->replace_node(n, top); 871 } 872 } 873 874 //------------------------------optimize_trichotomy-------------------------- 875 // Optimize nested comparisons of the following kind: 876 // 877 // int compare(int a, int b) { 878 // return (a < b) ? -1 : (a == b) ? 0 : 1; 879 // } 880 // 881 // Shape 1: 882 // if (compare(a, b) == 1) { ... } -> if (a > b) { ... } 883 // 884 // Shape 2: 885 // if (compare(a, b) == 0) { ... } -> if (a == b) { ... } 886 // 887 // Above code leads to the following IR shapes where both Ifs compare the 888 // same value and two out of three region inputs idx1 and idx2 map to 889 // the same value and control flow. 890 // 891 // (1) If (2) If 892 // / \ / \ 893 // Proj Proj Proj Proj 894 // | \ | \ 895 // | If | If If 896 // | / \ | / \ / \ 897 // | Proj Proj | Proj Proj ==> Proj Proj 898 // | / / \ | / | / 899 // Region / \ | / | / 900 // \ / \ | / | / 901 // Region Region Region 902 // 903 // The method returns true if 'this' is modified and false otherwise. 904 bool RegionNode::optimize_trichotomy(PhaseIterGVN* igvn) { 905 int idx1 = 1, idx2 = 2; 906 Node* region = nullptr; 907 if (req() == 3 && in(1) != nullptr && in(2) != nullptr) { 908 // Shape 1: Check if one of the inputs is a region that merges two control 909 // inputs and has no other users (especially no Phi users). 910 region = in(1)->isa_Region() ? in(1) : in(2)->isa_Region(); 911 if (region == nullptr || region->outcnt() != 2 || region->req() != 3) { 912 return false; // No suitable region input found 913 } 914 } else if (req() == 4) { 915 // Shape 2: Check if two control inputs map to the same value of the unique phi 916 // user and treat these as if they would come from another region (shape (1)). 917 PhiNode* phi = has_unique_phi(); 918 if (phi == nullptr) { 919 return false; // No unique phi user 920 } 921 if (phi->in(idx1) != phi->in(idx2)) { 922 idx2 = 3; 923 if (phi->in(idx1) != phi->in(idx2)) { 924 idx1 = 2; 925 if (phi->in(idx1) != phi->in(idx2)) { 926 return false; // No equal phi inputs found 927 } 928 } 929 } 930 assert(phi->in(idx1) == phi->in(idx2), "must be"); // Region is merging same value 931 region = this; 932 } 933 if (region == nullptr || region->in(idx1) == nullptr || region->in(idx2) == nullptr) { 934 return false; // Region does not merge two control inputs 935 } 936 // At this point we know that region->in(idx1) and region->(idx2) map to the same 937 // value and control flow. Now search for ifs that feed into these region inputs. 938 ProjNode* proj1 = region->in(idx1)->isa_Proj(); 939 ProjNode* proj2 = region->in(idx2)->isa_Proj(); 940 if (proj1 == nullptr || proj1->outcnt() != 1 || 941 proj2 == nullptr || proj2->outcnt() != 1) { 942 return false; // No projection inputs with region as unique user found 943 } 944 assert(proj1 != proj2, "should be different projections"); 945 IfNode* iff1 = proj1->in(0)->isa_If(); 946 IfNode* iff2 = proj2->in(0)->isa_If(); 947 if (iff1 == nullptr || iff1->outcnt() != 2 || 948 iff2 == nullptr || iff2->outcnt() != 2) { 949 return false; // No ifs found 950 } 951 if (iff1 == iff2) { 952 igvn->add_users_to_worklist(iff1); // Make sure dead if is eliminated 953 igvn->replace_input_of(region, idx1, iff1->in(0)); 954 igvn->replace_input_of(region, idx2, igvn->C->top()); 955 return (region == this); // Remove useless if (both projections map to the same control/value) 956 } 957 BoolNode* bol1 = iff1->in(1)->isa_Bool(); 958 BoolNode* bol2 = iff2->in(1)->isa_Bool(); 959 if (bol1 == nullptr || bol2 == nullptr) { 960 return false; // No bool inputs found 961 } 962 Node* cmp1 = bol1->in(1); 963 Node* cmp2 = bol2->in(1); 964 bool commute = false; 965 if (!cmp1->is_Cmp() || !cmp2->is_Cmp()) { 966 return false; // No comparison 967 } else if (cmp1->Opcode() == Op_CmpF || cmp1->Opcode() == Op_CmpD || 968 cmp2->Opcode() == Op_CmpF || cmp2->Opcode() == Op_CmpD || 969 cmp1->Opcode() == Op_CmpP || cmp1->Opcode() == Op_CmpN || 970 cmp2->Opcode() == Op_CmpP || cmp2->Opcode() == Op_CmpN || 971 cmp1->is_SubTypeCheck() || cmp2->is_SubTypeCheck() || 972 cmp1->is_FlatArrayCheck() || cmp2->is_FlatArrayCheck()) { 973 // Floats and pointers don't exactly obey trichotomy. To be on the safe side, don't transform their tests. 974 // SubTypeCheck is not commutative 975 return false; 976 } else if (cmp1 != cmp2) { 977 if (cmp1->in(1) == cmp2->in(2) && 978 cmp1->in(2) == cmp2->in(1)) { 979 commute = true; // Same but swapped inputs, commute the test 980 } else { 981 return false; // Ifs are not comparing the same values 982 } 983 } 984 proj1 = proj1->other_if_proj(); 985 proj2 = proj2->other_if_proj(); 986 if (!((proj1->unique_ctrl_out_or_null() == iff2 && 987 proj2->unique_ctrl_out_or_null() == this) || 988 (proj2->unique_ctrl_out_or_null() == iff1 && 989 proj1->unique_ctrl_out_or_null() == this))) { 990 return false; // Ifs are not connected through other projs 991 } 992 // Found 'iff -> proj -> iff -> proj -> this' shape where all other projs are merged 993 // through 'region' and map to the same value. Merge the boolean tests and replace 994 // the ifs by a single comparison. 995 BoolTest test1 = (proj1->_con == 1) ? bol1->_test : bol1->_test.negate(); 996 BoolTest test2 = (proj2->_con == 1) ? bol2->_test : bol2->_test.negate(); 997 test1 = commute ? test1.commute() : test1; 998 // After possibly commuting test1, if we can merge test1 & test2, then proj2/iff2/bol2 are the nodes to refine. 999 BoolTest::mask res = test1.merge(test2); 1000 if (res == BoolTest::illegal) { 1001 return false; // Unable to merge tests 1002 } 1003 // Adjust iff1 to always pass (only iff2 will remain) 1004 igvn->replace_input_of(iff1, 1, igvn->intcon(proj1->_con)); 1005 if (res == BoolTest::never) { 1006 // Merged test is always false, adjust iff2 to always fail 1007 igvn->replace_input_of(iff2, 1, igvn->intcon(1 - proj2->_con)); 1008 } else { 1009 // Replace bool input of iff2 with merged test 1010 BoolNode* new_bol = new BoolNode(bol2->in(1), res); 1011 igvn->replace_input_of(iff2, 1, igvn->transform((proj2->_con == 1) ? new_bol : new_bol->negate(igvn))); 1012 if (new_bol->outcnt() == 0) { 1013 igvn->remove_dead_node(new_bol); 1014 } 1015 } 1016 return false; 1017 } 1018 1019 const RegMask &RegionNode::out_RegMask() const { 1020 return RegMask::Empty; 1021 } 1022 1023 #ifndef PRODUCT 1024 void RegionNode::dump_spec(outputStream* st) const { 1025 Node::dump_spec(st); 1026 switch (loop_status()) { 1027 case RegionNode::LoopStatus::MaybeIrreducibleEntry: 1028 st->print("#irreducible "); 1029 break; 1030 case RegionNode::LoopStatus::Reducible: 1031 st->print("#reducible "); 1032 break; 1033 case RegionNode::LoopStatus::NeverIrreducibleEntry: 1034 break; // nothing 1035 } 1036 } 1037 #endif 1038 1039 // Find the one non-null required input. RegionNode only 1040 Node *Node::nonnull_req() const { 1041 assert( is_Region(), "" ); 1042 for( uint i = 1; i < _cnt; i++ ) 1043 if( in(i) ) 1044 return in(i); 1045 ShouldNotReachHere(); 1046 return nullptr; 1047 } 1048 1049 1050 //============================================================================= 1051 // note that these functions assume that the _adr_type field is flat 1052 uint PhiNode::hash() const { 1053 const Type* at = _adr_type; 1054 return TypeNode::hash() + (at ? at->hash() : 0); 1055 } 1056 bool PhiNode::cmp( const Node &n ) const { 1057 return TypeNode::cmp(n) && _adr_type == ((PhiNode&)n)._adr_type; 1058 } 1059 static inline 1060 const TypePtr* flatten_phi_adr_type(const TypePtr* at) { 1061 if (at == nullptr || at == TypePtr::BOTTOM) return at; 1062 return Compile::current()->alias_type(at)->adr_type(); 1063 } 1064 1065 //----------------------------make--------------------------------------------- 1066 // create a new phi with edges matching r and set (initially) to x 1067 PhiNode* PhiNode::make(Node* r, Node* x, const Type *t, const TypePtr* at) { 1068 uint preds = r->req(); // Number of predecessor paths 1069 assert(t != Type::MEMORY || at == flatten_phi_adr_type(at) || (flatten_phi_adr_type(at) == TypeAryPtr::INLINES && Compile::current()->flat_accesses_share_alias()), "flatten at"); 1070 PhiNode* p = new PhiNode(r, t, at); 1071 for (uint j = 1; j < preds; j++) { 1072 // Fill in all inputs, except those which the region does not yet have 1073 if (r->in(j) != nullptr) 1074 p->init_req(j, x); 1075 } 1076 return p; 1077 } 1078 PhiNode* PhiNode::make(Node* r, Node* x) { 1079 const Type* t = x->bottom_type(); 1080 const TypePtr* at = nullptr; 1081 if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type()); 1082 return make(r, x, t, at); 1083 } 1084 PhiNode* PhiNode::make_blank(Node* r, Node* x) { 1085 const Type* t = x->bottom_type(); 1086 const TypePtr* at = nullptr; 1087 if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type()); 1088 return new PhiNode(r, t, at); 1089 } 1090 1091 1092 //------------------------slice_memory----------------------------------------- 1093 // create a new phi with narrowed memory type 1094 PhiNode* PhiNode::slice_memory(const TypePtr* adr_type) const { 1095 PhiNode* mem = (PhiNode*) clone(); 1096 *(const TypePtr**)&mem->_adr_type = adr_type; 1097 // convert self-loops, or else we get a bad graph 1098 for (uint i = 1; i < req(); i++) { 1099 if ((const Node*)in(i) == this) mem->set_req(i, mem); 1100 } 1101 mem->verify_adr_type(); 1102 return mem; 1103 } 1104 1105 //------------------------split_out_instance----------------------------------- 1106 // Split out an instance type from a bottom phi. 1107 PhiNode* PhiNode::split_out_instance(const TypePtr* at, PhaseIterGVN *igvn) const { 1108 const TypeOopPtr *t_oop = at->isa_oopptr(); 1109 assert(t_oop != nullptr && t_oop->is_known_instance(), "expecting instance oopptr"); 1110 1111 // Check if an appropriate node already exists. 1112 Node *region = in(0); 1113 for (DUIterator_Fast kmax, k = region->fast_outs(kmax); k < kmax; k++) { 1114 Node* use = region->fast_out(k); 1115 if( use->is_Phi()) { 1116 PhiNode *phi2 = use->as_Phi(); 1117 if (phi2->type() == Type::MEMORY && phi2->adr_type() == at) { 1118 return phi2; 1119 } 1120 } 1121 } 1122 Compile *C = igvn->C; 1123 ResourceMark rm; 1124 Node_Array node_map; 1125 Node_Stack stack(C->live_nodes() >> 4); 1126 PhiNode *nphi = slice_memory(at); 1127 igvn->register_new_node_with_optimizer( nphi ); 1128 node_map.map(_idx, nphi); 1129 stack.push((Node *)this, 1); 1130 while(!stack.is_empty()) { 1131 PhiNode *ophi = stack.node()->as_Phi(); 1132 uint i = stack.index(); 1133 assert(i >= 1, "not control edge"); 1134 stack.pop(); 1135 nphi = node_map[ophi->_idx]->as_Phi(); 1136 for (; i < ophi->req(); i++) { 1137 Node *in = ophi->in(i); 1138 if (in == nullptr || igvn->type(in) == Type::TOP) 1139 continue; 1140 Node *opt = MemNode::optimize_simple_memory_chain(in, t_oop, nullptr, igvn); 1141 PhiNode *optphi = opt->is_Phi() ? opt->as_Phi() : nullptr; 1142 if (optphi != nullptr && optphi->adr_type() == TypePtr::BOTTOM) { 1143 opt = node_map[optphi->_idx]; 1144 if (opt == nullptr) { 1145 stack.push(ophi, i); 1146 nphi = optphi->slice_memory(at); 1147 igvn->register_new_node_with_optimizer( nphi ); 1148 node_map.map(optphi->_idx, nphi); 1149 ophi = optphi; 1150 i = 0; // will get incremented at top of loop 1151 continue; 1152 } 1153 } 1154 nphi->set_req(i, opt); 1155 } 1156 } 1157 return nphi; 1158 } 1159 1160 //------------------------verify_adr_type-------------------------------------- 1161 #ifdef ASSERT 1162 void PhiNode::verify_adr_type(VectorSet& visited, const TypePtr* at) const { 1163 if (visited.test_set(_idx)) return; //already visited 1164 1165 // recheck constructor invariants: 1166 verify_adr_type(false); 1167 1168 // recheck local phi/phi consistency: 1169 assert(_adr_type == at || _adr_type == TypePtr::BOTTOM, 1170 "adr_type must be consistent across phi nest"); 1171 1172 // walk around 1173 for (uint i = 1; i < req(); i++) { 1174 Node* n = in(i); 1175 if (n == nullptr) continue; 1176 const Node* np = in(i); 1177 if (np->is_Phi()) { 1178 np->as_Phi()->verify_adr_type(visited, at); 1179 } else if (n->bottom_type() == Type::TOP 1180 || (n->is_Mem() && n->in(MemNode::Address)->bottom_type() == Type::TOP)) { 1181 // ignore top inputs 1182 } else { 1183 const TypePtr* nat = flatten_phi_adr_type(n->adr_type()); 1184 // recheck phi/non-phi consistency at leaves: 1185 assert((nat != nullptr) == (at != nullptr), ""); 1186 assert(nat == at || nat == TypePtr::BOTTOM, 1187 "adr_type must be consistent at leaves of phi nest"); 1188 } 1189 } 1190 } 1191 1192 // Verify a whole nest of phis rooted at this one. 1193 void PhiNode::verify_adr_type(bool recursive) const { 1194 if (VMError::is_error_reported()) return; // muzzle asserts when debugging an error 1195 if (Node::in_dump()) return; // muzzle asserts when printing 1196 1197 assert((_type == Type::MEMORY) == (_adr_type != nullptr), "adr_type for memory phis only"); 1198 // Flat array element shouldn't get their own memory slice until flat_accesses_share_alias is cleared. 1199 // It could be the graph has no loads/stores and flat_accesses_share_alias is never cleared. EA could still 1200 // creates per element Phis but that wouldn't be a problem as there are no memory accesses for that array. 1201 assert(_adr_type == nullptr || _adr_type->isa_aryptr() == nullptr || 1202 _adr_type->is_aryptr()->is_known_instance() || 1203 !_adr_type->is_aryptr()->is_flat() || 1204 !Compile::current()->flat_accesses_share_alias() || 1205 _adr_type == TypeAryPtr::INLINES, "flat array element shouldn't get its own slice yet"); 1206 1207 if (!VerifyAliases) return; // verify thoroughly only if requested 1208 1209 assert(_adr_type == flatten_phi_adr_type(_adr_type), 1210 "Phi::adr_type must be pre-normalized"); 1211 1212 if (recursive) { 1213 VectorSet visited; 1214 verify_adr_type(visited, _adr_type); 1215 } 1216 } 1217 #endif 1218 1219 1220 //------------------------------Value------------------------------------------ 1221 // Compute the type of the PhiNode 1222 const Type* PhiNode::Value(PhaseGVN* phase) const { 1223 Node *r = in(0); // RegionNode 1224 if( !r ) // Copy or dead 1225 return in(1) ? phase->type(in(1)) : Type::TOP; 1226 1227 // Note: During parsing, phis are often transformed before their regions. 1228 // This means we have to use type_or_null to defend against untyped regions. 1229 if( phase->type_or_null(r) == Type::TOP ) // Dead code? 1230 return Type::TOP; 1231 1232 // Check for trip-counted loop. If so, be smarter. 1233 BaseCountedLoopNode* l = r->is_BaseCountedLoop() ? r->as_BaseCountedLoop() : nullptr; 1234 if (l && ((const Node*)l->phi() == this)) { // Trip counted loop! 1235 // protect against init_trip() or limit() returning null 1236 if (l->can_be_counted_loop(phase)) { 1237 const Node* init = l->init_trip(); 1238 const Node* limit = l->limit(); 1239 const Node* stride = l->stride(); 1240 if (init != nullptr && limit != nullptr && stride != nullptr) { 1241 const TypeInteger* lo = phase->type(init)->isa_integer(l->bt()); 1242 const TypeInteger* hi = phase->type(limit)->isa_integer(l->bt()); 1243 const TypeInteger* stride_t = phase->type(stride)->isa_integer(l->bt()); 1244 if (lo != nullptr && hi != nullptr && stride_t != nullptr) { // Dying loops might have TOP here 1245 assert(stride_t->is_con(), "bad stride type"); 1246 BoolTest::mask bt = l->loopexit()->test_trip(); 1247 // If the loop exit condition is "not equal", the condition 1248 // would not trigger if init > limit (if stride > 0) or if 1249 // init < limit if (stride > 0) so we can't deduce bounds 1250 // for the iv from the exit condition. 1251 if (bt != BoolTest::ne) { 1252 jlong stride_con = stride_t->get_con_as_long(l->bt()); 1253 if (stride_con < 0) { // Down-counter loop 1254 swap(lo, hi); 1255 jlong iv_range_lower_limit = lo->lo_as_long(); 1256 // Prevent overflow when adding one below 1257 if (iv_range_lower_limit < max_signed_integer(l->bt())) { 1258 // The loop exit condition is: iv + stride > limit (iv is this Phi). So the loop iterates until 1259 // iv + stride <= limit 1260 // We know that: limit >= lo->lo_as_long() and stride <= -1 1261 // So when the loop exits, iv has to be at most lo->lo_as_long() + 1 1262 iv_range_lower_limit += 1; // lo is after decrement 1263 // Exact bounds for the phi can be computed when ABS(stride) greater than 1 if bounds are constant. 1264 if (lo->is_con() && hi->is_con() && hi->lo_as_long() > lo->hi_as_long() && stride_con != -1) { 1265 julong uhi = static_cast<julong>(hi->lo_as_long()); 1266 julong ulo = static_cast<julong>(lo->hi_as_long()); 1267 julong diff = ((uhi - ulo - 1) / (-stride_con)) * (-stride_con); 1268 julong ufirst = hi->lo_as_long() - diff; 1269 iv_range_lower_limit = reinterpret_cast<jlong &>(ufirst); 1270 assert(iv_range_lower_limit >= lo->lo_as_long() + 1, "should end up with narrower range"); 1271 } 1272 } 1273 return TypeInteger::make(MIN2(iv_range_lower_limit, hi->lo_as_long()), hi->hi_as_long(), 3, l->bt())->filter_speculative(_type); 1274 } else if (stride_con >= 0) { 1275 jlong iv_range_upper_limit = hi->hi_as_long(); 1276 // Prevent overflow when subtracting one below 1277 if (iv_range_upper_limit > min_signed_integer(l->bt())) { 1278 // The loop exit condition is: iv + stride < limit (iv is this Phi). So the loop iterates until 1279 // iv + stride >= limit 1280 // We know that: limit <= hi->hi_as_long() and stride >= 1 1281 // So when the loop exits, iv has to be at most hi->hi_as_long() - 1 1282 iv_range_upper_limit -= 1; 1283 // Exact bounds for the phi can be computed when ABS(stride) greater than 1 if bounds are constant. 1284 if (lo->is_con() && hi->is_con() && hi->lo_as_long() > lo->hi_as_long() && stride_con != 1) { 1285 julong uhi = static_cast<julong>(hi->lo_as_long()); 1286 julong ulo = static_cast<julong>(lo->hi_as_long()); 1287 julong diff = ((uhi - ulo - 1) / stride_con) * stride_con; 1288 julong ulast = lo->hi_as_long() + diff; 1289 iv_range_upper_limit = reinterpret_cast<jlong &>(ulast); 1290 assert(iv_range_upper_limit <= hi->hi_as_long() - 1, "should end up with narrower range"); 1291 } 1292 } 1293 return TypeInteger::make(lo->lo_as_long(), MAX2(lo->hi_as_long(), iv_range_upper_limit), 3, l->bt())->filter_speculative(_type); 1294 } 1295 } 1296 } 1297 } 1298 } else if (l->in(LoopNode::LoopBackControl) != nullptr && 1299 in(LoopNode::EntryControl) != nullptr && 1300 phase->type(l->in(LoopNode::LoopBackControl)) == Type::TOP) { 1301 // During CCP, if we saturate the type of a counted loop's Phi 1302 // before the special code for counted loop above has a chance 1303 // to run (that is as long as the type of the backedge's control 1304 // is top), we might end up with non monotonic types 1305 return phase->type(in(LoopNode::EntryControl))->filter_speculative(_type); 1306 } 1307 } 1308 1309 // Default case: merge all inputs 1310 const Type *t = Type::TOP; // Merged type starting value 1311 for (uint i = 1; i < req(); ++i) {// For all paths in 1312 // Reachable control path? 1313 if (r->in(i) && phase->type(r->in(i)) == Type::CONTROL) { 1314 const Type* ti = phase->type(in(i)); 1315 t = t->meet_speculative(ti); 1316 } 1317 } 1318 1319 // The worst-case type (from ciTypeFlow) should be consistent with "t". 1320 // That is, we expect that "t->higher_equal(_type)" holds true. 1321 // There are various exceptions: 1322 // - Inputs which are phis might in fact be widened unnecessarily. 1323 // For example, an input might be a widened int while the phi is a short. 1324 // - Inputs might be BotPtrs but this phi is dependent on a null check, 1325 // and postCCP has removed the cast which encodes the result of the check. 1326 // - The type of this phi is an interface, and the inputs are classes. 1327 // - Value calls on inputs might produce fuzzy results. 1328 // (Occurrences of this case suggest improvements to Value methods.) 1329 // 1330 // It is not possible to see Type::BOTTOM values as phi inputs, 1331 // because the ciTypeFlow pre-pass produces verifier-quality types. 1332 const Type* ft = t->filter_speculative(_type); // Worst case type 1333 1334 #ifdef ASSERT 1335 // The following logic has been moved into TypeOopPtr::filter. 1336 const Type* jt = t->join_speculative(_type); 1337 if (jt->empty()) { // Emptied out??? 1338 // Otherwise it's something stupid like non-overlapping int ranges 1339 // found on dying counted loops. 1340 assert(ft == Type::TOP, ""); // Canonical empty value 1341 } 1342 1343 else { 1344 1345 if (jt != ft && jt->base() == ft->base()) { 1346 if (jt->isa_int() && 1347 jt->is_int()->_lo == ft->is_int()->_lo && 1348 jt->is_int()->_hi == ft->is_int()->_hi) 1349 jt = ft; 1350 if (jt->isa_long() && 1351 jt->is_long()->_lo == ft->is_long()->_lo && 1352 jt->is_long()->_hi == ft->is_long()->_hi) 1353 jt = ft; 1354 } 1355 if (jt != ft) { 1356 tty->print("merge type: "); t->dump(); tty->cr(); 1357 tty->print("kill type: "); _type->dump(); tty->cr(); 1358 tty->print("join type: "); jt->dump(); tty->cr(); 1359 tty->print("filter type: "); ft->dump(); tty->cr(); 1360 } 1361 assert(jt == ft, ""); 1362 } 1363 #endif //ASSERT 1364 1365 // Deal with conversion problems found in data loops. 1366 ft = phase->saturate_and_maybe_push_to_igvn_worklist(this, ft); 1367 return ft; 1368 } 1369 1370 // Does this Phi represent a simple well-shaped diamond merge? Return the 1371 // index of the true path or 0 otherwise. 1372 int PhiNode::is_diamond_phi() const { 1373 Node* region = in(0); 1374 assert(region != nullptr && region->is_Region(), "phi must have region"); 1375 if (!region->as_Region()->is_diamond()) { 1376 return 0; 1377 } 1378 1379 if (region->in(1)->is_IfTrue()) { 1380 assert(region->in(2)->is_IfFalse(), "bad If"); 1381 return 1; 1382 } else { 1383 // Flipped projections. 1384 assert(region->in(2)->is_IfTrue(), "bad If"); 1385 return 2; 1386 } 1387 } 1388 1389 // Do the following transformation if we find the corresponding graph shape, remove the involved memory phi and return 1390 // true. Otherwise, return false if the transformation cannot be applied. 1391 // 1392 // If If 1393 // / \ / \ 1394 // IfFalse IfTrue /- Some Node IfFalse IfTrue 1395 // \ / / / \ / Some Node 1396 // Region / /-MergeMem ===> Region | 1397 // / \---Phi | MergeMem 1398 // [other phis] \ [other phis] | 1399 // use use 1400 bool PhiNode::try_clean_memory_phi(PhaseIterGVN* igvn) { 1401 if (_type != Type::MEMORY) { 1402 return false; 1403 } 1404 assert(is_diamond_phi() > 0, "sanity"); 1405 assert(req() == 3, "same as region"); 1406 const Node* region = in(0); 1407 for (uint i = 1; i < 3; i++) { 1408 Node* phi_input = in(i); 1409 if (phi_input != nullptr && phi_input->is_MergeMem() && region->in(i)->outcnt() == 1) { 1410 // Nothing is control-dependent on path #i except the region itself. 1411 MergeMemNode* merge_mem = phi_input->as_MergeMem(); 1412 uint j = 3 - i; 1413 Node* other_phi_input = in(j); 1414 if (other_phi_input != nullptr && other_phi_input == merge_mem->base_memory()) { 1415 // merge_mem is a successor memory to other_phi_input, and is not pinned inside the diamond, so push it out. 1416 // This will allow the diamond to collapse completely if there are no other phis left. 1417 igvn->replace_node(this, merge_mem); 1418 return true; 1419 } 1420 } 1421 } 1422 return false; 1423 } 1424 1425 //----------------------------check_cmove_id----------------------------------- 1426 // Check for CMove'ing a constant after comparing against the constant. 1427 // Happens all the time now, since if we compare equality vs a constant in 1428 // the parser, we "know" the variable is constant on one path and we force 1429 // it. Thus code like "if( x==0 ) {/*EMPTY*/}" ends up inserting a 1430 // conditional move: "x = (x==0)?0:x;". Yucko. This fix is slightly more 1431 // general in that we don't need constants. Since CMove's are only inserted 1432 // in very special circumstances, we do it here on generic Phi's. 1433 Node* PhiNode::is_cmove_id(PhaseTransform* phase, int true_path) { 1434 assert(true_path !=0, "only diamond shape graph expected"); 1435 1436 // is_diamond_phi() has guaranteed the correctness of the nodes sequence: 1437 // phi->region->if_proj->ifnode->bool->cmp 1438 Node* region = in(0); 1439 Node* iff = region->in(1)->in(0); 1440 BoolNode* b = iff->in(1)->as_Bool(); 1441 Node* cmp = b->in(1); 1442 Node* tval = in(true_path); 1443 Node* fval = in(3-true_path); 1444 Node* id = CMoveNode::is_cmove_id(phase, cmp, tval, fval, b); 1445 if (id == nullptr) 1446 return nullptr; 1447 1448 // Either value might be a cast that depends on a branch of 'iff'. 1449 // Since the 'id' value will float free of the diamond, either 1450 // decast or return failure. 1451 Node* ctl = id->in(0); 1452 if (ctl != nullptr && ctl->in(0) == iff) { 1453 if (id->is_ConstraintCast()) { 1454 return id->in(1); 1455 } else { 1456 // Don't know how to disentangle this value. 1457 return nullptr; 1458 } 1459 } 1460 1461 return id; 1462 } 1463 1464 //------------------------------Identity--------------------------------------- 1465 // Check for Region being Identity. 1466 Node* PhiNode::Identity(PhaseGVN* phase) { 1467 if (must_wait_for_region_in_irreducible_loop(phase)) { 1468 return this; 1469 } 1470 // Check for no merging going on 1471 // (There used to be special-case code here when this->region->is_Loop. 1472 // It would check for a tributary phi on the backedge that the main phi 1473 // trivially, perhaps with a single cast. The unique_input method 1474 // does all this and more, by reducing such tributaries to 'this'.) 1475 Node* uin = unique_input(phase, false); 1476 if (uin != nullptr) { 1477 return uin; 1478 } 1479 uin = unique_input_recursive(phase); 1480 if (uin != nullptr) { 1481 return uin; 1482 } 1483 1484 int true_path = is_diamond_phi(); 1485 // Delay CMove'ing identity if Ideal has not had the chance to handle unsafe cases, yet. 1486 if (true_path != 0 && !(phase->is_IterGVN() && wait_for_region_igvn(phase))) { 1487 Node* id = is_cmove_id(phase, true_path); 1488 if (id != nullptr) { 1489 return id; 1490 } 1491 } 1492 1493 // Looking for phis with identical inputs. If we find one that has 1494 // type TypePtr::BOTTOM, replace the current phi with the bottom phi. 1495 if (phase->is_IterGVN() && type() == Type::MEMORY && adr_type() != 1496 TypePtr::BOTTOM && !adr_type()->is_known_instance()) { 1497 uint phi_len = req(); 1498 Node* phi_reg = region(); 1499 for (DUIterator_Fast imax, i = phi_reg->fast_outs(imax); i < imax; i++) { 1500 Node* u = phi_reg->fast_out(i); 1501 if (u->is_Phi() && u->as_Phi()->type() == Type::MEMORY && 1502 u->adr_type() == TypePtr::BOTTOM && u->in(0) == phi_reg && 1503 u->req() == phi_len) { 1504 for (uint j = 1; j < phi_len; j++) { 1505 if (in(j) != u->in(j)) { 1506 u = nullptr; 1507 break; 1508 } 1509 } 1510 if (u != nullptr) { 1511 return u; 1512 } 1513 } 1514 } 1515 } 1516 1517 return this; // No identity 1518 } 1519 1520 //-----------------------------unique_input------------------------------------ 1521 // Find the unique value, discounting top, self-loops, and casts. 1522 // Return top if there are no inputs, and self if there are multiple. 1523 Node* PhiNode::unique_input(PhaseValues* phase, bool uncast) { 1524 // 1) One unique direct input, 1525 // or if uncast is true: 1526 // 2) some of the inputs have an intervening ConstraintCast 1527 // 3) an input is a self loop 1528 // 1529 // 1) input or 2) input or 3) input __ 1530 // / \ / \ \ / \ 1531 // \ / | cast phi cast 1532 // phi \ / / \ / 1533 // phi / -- 1534 1535 Node* r = in(0); // RegionNode 1536 Node* input = nullptr; // The unique direct input (maybe uncasted = ConstraintCasts removed) 1537 1538 for (uint i = 1, cnt = req(); i < cnt; ++i) { 1539 Node* rc = r->in(i); 1540 if (rc == nullptr || phase->type(rc) == Type::TOP) 1541 continue; // ignore unreachable control path 1542 Node* n = in(i); 1543 if (n == nullptr) 1544 continue; 1545 Node* un = n; 1546 if (uncast) { 1547 #ifdef ASSERT 1548 Node* m = un->uncast(); 1549 #endif 1550 while (un != nullptr && un->req() == 2 && un->is_ConstraintCast()) { 1551 Node* next = un->in(1); 1552 if (phase->type(next)->isa_rawptr() && phase->type(un)->isa_oopptr()) { 1553 // risk exposing raw ptr at safepoint 1554 break; 1555 } 1556 un = next; 1557 } 1558 assert(m == un || un->in(1) == m, "Only expected at CheckCastPP from allocation"); 1559 } 1560 if (un == nullptr || un == this || phase->type(un) == Type::TOP) { 1561 continue; // ignore if top, or in(i) and "this" are in a data cycle 1562 } 1563 // Check for a unique input (maybe uncasted) 1564 if (input == nullptr) { 1565 input = un; 1566 } else if (input != un) { 1567 input = NodeSentinel; // no unique input 1568 } 1569 } 1570 if (input == nullptr) { 1571 return phase->C->top(); // no inputs 1572 } 1573 1574 if (input != NodeSentinel) { 1575 return input; // one unique direct input 1576 } 1577 1578 // Nothing. 1579 return nullptr; 1580 } 1581 1582 // Find the unique input, try to look recursively through input Phis 1583 Node* PhiNode::unique_input_recursive(PhaseGVN* phase) { 1584 if (!phase->is_IterGVN()) { 1585 return nullptr; 1586 } 1587 1588 ResourceMark rm; 1589 Node* unique = nullptr; 1590 Unique_Node_List visited; 1591 visited.push(this); 1592 1593 for (uint visited_idx = 0; visited_idx < visited.size(); visited_idx++) { 1594 Node* current = visited.at(visited_idx); 1595 for (uint i = 1; i < current->req(); i++) { 1596 Node* phi_in = current->in(i); 1597 if (phi_in == nullptr) { 1598 continue; 1599 } 1600 1601 if (phi_in->is_Phi()) { 1602 visited.push(phi_in); 1603 } else { 1604 if (unique == nullptr) { 1605 unique = phi_in; 1606 } else if (unique != phi_in) { 1607 return nullptr; 1608 } 1609 } 1610 } 1611 } 1612 return unique; 1613 } 1614 1615 //------------------------------is_x2logic------------------------------------- 1616 // Check for simple convert-to-boolean pattern 1617 // If:(C Bool) Region:(IfF IfT) Phi:(Region 0 1) 1618 // Convert Phi to an ConvIB. 1619 static Node *is_x2logic( PhaseGVN *phase, PhiNode *phi, int true_path ) { 1620 assert(true_path !=0, "only diamond shape graph expected"); 1621 1622 // If we're late in the optimization process, we may have already expanded Conv2B nodes 1623 if (phase->C->post_loop_opts_phase() && !Matcher::match_rule_supported(Op_Conv2B)) { 1624 return nullptr; 1625 } 1626 1627 // Convert the true/false index into an expected 0/1 return. 1628 // Map 2->0 and 1->1. 1629 int flipped = 2-true_path; 1630 1631 // is_diamond_phi() has guaranteed the correctness of the nodes sequence: 1632 // phi->region->if_proj->ifnode->bool->cmp 1633 Node *region = phi->in(0); 1634 Node *iff = region->in(1)->in(0); 1635 BoolNode *b = (BoolNode*)iff->in(1); 1636 const CmpNode *cmp = (CmpNode*)b->in(1); 1637 1638 Node *zero = phi->in(1); 1639 Node *one = phi->in(2); 1640 const Type *tzero = phase->type( zero ); 1641 const Type *tone = phase->type( one ); 1642 1643 // Check for compare vs 0 1644 const Type *tcmp = phase->type(cmp->in(2)); 1645 if( tcmp != TypeInt::ZERO && tcmp != TypePtr::NULL_PTR ) { 1646 // Allow cmp-vs-1 if the other input is bounded by 0-1 1647 if( !(tcmp == TypeInt::ONE && phase->type(cmp->in(1)) == TypeInt::BOOL) ) 1648 return nullptr; 1649 flipped = 1-flipped; // Test is vs 1 instead of 0! 1650 } 1651 1652 // Check for setting zero/one opposite expected 1653 if( tzero == TypeInt::ZERO ) { 1654 if( tone == TypeInt::ONE ) { 1655 } else return nullptr; 1656 } else if( tzero == TypeInt::ONE ) { 1657 if( tone == TypeInt::ZERO ) { 1658 flipped = 1-flipped; 1659 } else return nullptr; 1660 } else return nullptr; 1661 1662 // Check for boolean test backwards 1663 if( b->_test._test == BoolTest::ne ) { 1664 } else if( b->_test._test == BoolTest::eq ) { 1665 flipped = 1-flipped; 1666 } else return nullptr; 1667 1668 // Build int->bool conversion 1669 Node* n = new Conv2BNode(cmp->in(1)); 1670 if (flipped) { 1671 n = new XorINode(phase->transform(n), phase->intcon(1)); 1672 } 1673 1674 return n; 1675 } 1676 1677 //------------------------------is_cond_add------------------------------------ 1678 // Check for simple conditional add pattern: "(P < Q) ? X+Y : X;" 1679 // To be profitable the control flow has to disappear; there can be no other 1680 // values merging here. We replace the test-and-branch with: 1681 // "(sgn(P-Q))&Y) + X". Basically, convert "(P < Q)" into 0 or -1 by 1682 // moving the carry bit from (P-Q) into a register with 'sbb EAX,EAX'. 1683 // Then convert Y to 0-or-Y and finally add. 1684 // This is a key transform for SpecJava _201_compress. 1685 static Node* is_cond_add(PhaseGVN *phase, PhiNode *phi, int true_path) { 1686 assert(true_path !=0, "only diamond shape graph expected"); 1687 1688 // is_diamond_phi() has guaranteed the correctness of the nodes sequence: 1689 // phi->region->if_proj->ifnode->bool->cmp 1690 RegionNode *region = (RegionNode*)phi->in(0); 1691 Node *iff = region->in(1)->in(0); 1692 BoolNode* b = iff->in(1)->as_Bool(); 1693 const CmpNode *cmp = (CmpNode*)b->in(1); 1694 1695 // Make sure only merging this one phi here 1696 if (region->has_unique_phi() != phi) return nullptr; 1697 1698 // Make sure each arm of the diamond has exactly one output, which we assume 1699 // is the region. Otherwise, the control flow won't disappear. 1700 if (region->in(1)->outcnt() != 1) return nullptr; 1701 if (region->in(2)->outcnt() != 1) return nullptr; 1702 1703 // Check for "(P < Q)" of type signed int 1704 if (b->_test._test != BoolTest::lt) return nullptr; 1705 if (cmp->Opcode() != Op_CmpI) return nullptr; 1706 1707 Node *p = cmp->in(1); 1708 Node *q = cmp->in(2); 1709 Node *n1 = phi->in( true_path); 1710 Node *n2 = phi->in(3-true_path); 1711 1712 int op = n1->Opcode(); 1713 if( op != Op_AddI // Need zero as additive identity 1714 /*&&op != Op_SubI && 1715 op != Op_AddP && 1716 op != Op_XorI && 1717 op != Op_OrI*/ ) 1718 return nullptr; 1719 1720 Node *x = n2; 1721 Node *y = nullptr; 1722 if( x == n1->in(1) ) { 1723 y = n1->in(2); 1724 } else if( x == n1->in(2) ) { 1725 y = n1->in(1); 1726 } else return nullptr; 1727 1728 // Not so profitable if compare and add are constants 1729 if( q->is_Con() && phase->type(q) != TypeInt::ZERO && y->is_Con() ) 1730 return nullptr; 1731 1732 Node *cmplt = phase->transform( new CmpLTMaskNode(p,q) ); 1733 Node *j_and = phase->transform( new AndINode(cmplt,y) ); 1734 return new AddINode(j_and,x); 1735 } 1736 1737 //------------------------------is_absolute------------------------------------ 1738 // Check for absolute value. 1739 static Node* is_absolute( PhaseGVN *phase, PhiNode *phi_root, int true_path) { 1740 assert(true_path !=0, "only diamond shape graph expected"); 1741 1742 int cmp_zero_idx = 0; // Index of compare input where to look for zero 1743 int phi_x_idx = 0; // Index of phi input where to find naked x 1744 1745 // ABS ends with the merge of 2 control flow paths. 1746 // Find the false path from the true path. With only 2 inputs, 3 - x works nicely. 1747 int false_path = 3 - true_path; 1748 1749 // is_diamond_phi() has guaranteed the correctness of the nodes sequence: 1750 // phi->region->if_proj->ifnode->bool->cmp 1751 BoolNode *bol = phi_root->in(0)->in(1)->in(0)->in(1)->as_Bool(); 1752 Node *cmp = bol->in(1); 1753 1754 // Check bool sense 1755 if (cmp->Opcode() == Op_CmpF || cmp->Opcode() == Op_CmpD) { 1756 switch (bol->_test._test) { 1757 case BoolTest::lt: cmp_zero_idx = 1; phi_x_idx = true_path; break; 1758 case BoolTest::le: cmp_zero_idx = 2; phi_x_idx = false_path; break; 1759 case BoolTest::gt: cmp_zero_idx = 2; phi_x_idx = true_path; break; 1760 case BoolTest::ge: cmp_zero_idx = 1; phi_x_idx = false_path; break; 1761 default: return nullptr; break; 1762 } 1763 } else if (cmp->Opcode() == Op_CmpI || cmp->Opcode() == Op_CmpL) { 1764 switch (bol->_test._test) { 1765 case BoolTest::lt: 1766 case BoolTest::le: cmp_zero_idx = 2; phi_x_idx = false_path; break; 1767 case BoolTest::gt: 1768 case BoolTest::ge: cmp_zero_idx = 2; phi_x_idx = true_path; break; 1769 default: return nullptr; break; 1770 } 1771 } 1772 1773 // Test is next 1774 const Type *tzero = nullptr; 1775 switch (cmp->Opcode()) { 1776 case Op_CmpI: tzero = TypeInt::ZERO; break; // Integer ABS 1777 case Op_CmpL: tzero = TypeLong::ZERO; break; // Long ABS 1778 case Op_CmpF: tzero = TypeF::ZERO; break; // Float ABS 1779 case Op_CmpD: tzero = TypeD::ZERO; break; // Double ABS 1780 default: return nullptr; 1781 } 1782 1783 // Find zero input of compare; the other input is being abs'd 1784 Node *x = nullptr; 1785 bool flip = false; 1786 if( phase->type(cmp->in(cmp_zero_idx)) == tzero ) { 1787 x = cmp->in(3 - cmp_zero_idx); 1788 } else if( phase->type(cmp->in(3 - cmp_zero_idx)) == tzero ) { 1789 // The test is inverted, we should invert the result... 1790 x = cmp->in(cmp_zero_idx); 1791 flip = true; 1792 } else { 1793 return nullptr; 1794 } 1795 1796 // Next get the 2 pieces being selected, one is the original value 1797 // and the other is the negated value. 1798 if( phi_root->in(phi_x_idx) != x ) return nullptr; 1799 1800 // Check other phi input for subtract node 1801 Node *sub = phi_root->in(3 - phi_x_idx); 1802 1803 bool is_sub = sub->Opcode() == Op_SubF || sub->Opcode() == Op_SubD || 1804 sub->Opcode() == Op_SubI || sub->Opcode() == Op_SubL; 1805 1806 // Allow only Sub(0,X) and fail out for all others; Neg is not OK 1807 if (!is_sub || phase->type(sub->in(1)) != tzero || sub->in(2) != x) return nullptr; 1808 1809 if (tzero == TypeF::ZERO) { 1810 x = new AbsFNode(x); 1811 if (flip) { 1812 x = new SubFNode(sub->in(1), phase->transform(x)); 1813 } 1814 } else if (tzero == TypeD::ZERO) { 1815 x = new AbsDNode(x); 1816 if (flip) { 1817 x = new SubDNode(sub->in(1), phase->transform(x)); 1818 } 1819 } else if (tzero == TypeInt::ZERO && Matcher::match_rule_supported(Op_AbsI)) { 1820 x = new AbsINode(x); 1821 if (flip) { 1822 x = new SubINode(sub->in(1), phase->transform(x)); 1823 } 1824 } else if (tzero == TypeLong::ZERO && Matcher::match_rule_supported(Op_AbsL)) { 1825 x = new AbsLNode(x); 1826 if (flip) { 1827 x = new SubLNode(sub->in(1), phase->transform(x)); 1828 } 1829 } else return nullptr; 1830 1831 return x; 1832 } 1833 1834 //------------------------------split_once------------------------------------- 1835 // Helper for split_flow_path 1836 static void split_once(PhaseIterGVN *igvn, Node *phi, Node *val, Node *n, Node *newn) { 1837 igvn->hash_delete(n); // Remove from hash before hacking edges 1838 1839 uint j = 1; 1840 for (uint i = phi->req()-1; i > 0; i--) { 1841 if (phi->in(i) == val) { // Found a path with val? 1842 // Add to NEW Region/Phi, no DU info 1843 newn->set_req( j++, n->in(i) ); 1844 // Remove from OLD Region/Phi 1845 n->del_req(i); 1846 } 1847 } 1848 1849 // Register the new node but do not transform it. Cannot transform until the 1850 // entire Region/Phi conglomerate has been hacked as a single huge transform. 1851 igvn->register_new_node_with_optimizer( newn ); 1852 1853 // Now I can point to the new node. 1854 n->add_req(newn); 1855 igvn->_worklist.push(n); 1856 } 1857 1858 //------------------------------split_flow_path-------------------------------- 1859 // Check for merging identical values and split flow paths 1860 static Node* split_flow_path(PhaseGVN *phase, PhiNode *phi) { 1861 // This optimization tries to find two or more inputs of phi with the same constant value 1862 // It then splits them into a separate Phi, and according Region. If this is a loop-entry, 1863 // and the loop entry has multiple fall-in edges, and some of those fall-in edges have that 1864 // constant, and others not, we may split the fall-in edges into separate Phi's, and create 1865 // an irreducible loop. For reducible loops, this never seems to happen, as the multiple 1866 // fall-in edges are already merged before the loop head during parsing. But with irreducible 1867 // loops present the order or merging during parsing can sometimes prevent this. 1868 if (phase->C->has_irreducible_loop()) { 1869 // Avoid this optimization if any irreducible loops are present. Else we may create 1870 // an irreducible loop that we do not detect. 1871 return nullptr; 1872 } 1873 BasicType bt = phi->type()->basic_type(); 1874 if( bt == T_ILLEGAL || type2size[bt] <= 0 ) 1875 return nullptr; // Bail out on funny non-value stuff 1876 if( phi->req() <= 3 ) // Need at least 2 matched inputs and a 1877 return nullptr; // third unequal input to be worth doing 1878 1879 // Scan for a constant 1880 uint i; 1881 for( i = 1; i < phi->req()-1; i++ ) { 1882 Node *n = phi->in(i); 1883 if( !n ) return nullptr; 1884 if( phase->type(n) == Type::TOP ) return nullptr; 1885 if( n->Opcode() == Op_ConP || n->Opcode() == Op_ConN || n->Opcode() == Op_ConNKlass ) 1886 break; 1887 } 1888 if( i >= phi->req() ) // Only split for constants 1889 return nullptr; 1890 1891 Node *val = phi->in(i); // Constant to split for 1892 uint hit = 0; // Number of times it occurs 1893 Node *r = phi->region(); 1894 1895 for( ; i < phi->req(); i++ ){ // Count occurrences of constant 1896 Node *n = phi->in(i); 1897 if( !n ) return nullptr; 1898 if( phase->type(n) == Type::TOP ) return nullptr; 1899 if( phi->in(i) == val ) { 1900 hit++; 1901 if (Node::may_be_loop_entry(r->in(i))) { 1902 return nullptr; // don't split loop entry path 1903 } 1904 } 1905 } 1906 1907 if( hit <= 1 || // Make sure we find 2 or more 1908 hit == phi->req()-1 ) // and not ALL the same value 1909 return nullptr; 1910 1911 // Now start splitting out the flow paths that merge the same value. 1912 // Split first the RegionNode. 1913 PhaseIterGVN *igvn = phase->is_IterGVN(); 1914 RegionNode *newr = new RegionNode(hit+1); 1915 split_once(igvn, phi, val, r, newr); 1916 1917 // Now split all other Phis than this one 1918 for (DUIterator_Fast kmax, k = r->fast_outs(kmax); k < kmax; k++) { 1919 Node* phi2 = r->fast_out(k); 1920 if( phi2->is_Phi() && phi2->as_Phi() != phi ) { 1921 PhiNode *newphi = PhiNode::make_blank(newr, phi2); 1922 split_once(igvn, phi, val, phi2, newphi); 1923 } 1924 } 1925 1926 // Clean up this guy 1927 igvn->hash_delete(phi); 1928 for( i = phi->req()-1; i > 0; i-- ) { 1929 if( phi->in(i) == val ) { 1930 phi->del_req(i); 1931 } 1932 } 1933 phi->add_req(val); 1934 1935 return phi; 1936 } 1937 1938 // Returns the BasicType of a given convert node and a type, with special handling to ensure that conversions to 1939 // and from half float will return the SHORT basic type, as that wouldn't be returned typically from TypeInt. 1940 static BasicType get_convert_type(Node* convert, const Type* type) { 1941 int convert_op = convert->Opcode(); 1942 if (type->isa_int() && (convert_op == Op_ConvHF2F || convert_op == Op_ConvF2HF)) { 1943 return T_SHORT; 1944 } 1945 1946 return type->basic_type(); 1947 } 1948 1949 //============================================================================= 1950 //------------------------------simple_data_loop_check------------------------- 1951 // Try to determining if the phi node in a simple safe/unsafe data loop. 1952 // Returns: 1953 // enum LoopSafety { Safe = 0, Unsafe, UnsafeLoop }; 1954 // Safe - safe case when the phi and it's inputs reference only safe data 1955 // nodes; 1956 // Unsafe - the phi and it's inputs reference unsafe data nodes but there 1957 // is no reference back to the phi - need a graph walk 1958 // to determine if it is in a loop; 1959 // UnsafeLoop - unsafe case when the phi references itself directly or through 1960 // unsafe data node. 1961 // Note: a safe data node is a node which could/never reference itself during 1962 // GVN transformations. For now it is Con, Proj, Phi, CastPP, CheckCastPP. 1963 // I mark Phi nodes as safe node not only because they can reference itself 1964 // but also to prevent mistaking the fallthrough case inside an outer loop 1965 // as dead loop when the phi references itself through an other phi. 1966 PhiNode::LoopSafety PhiNode::simple_data_loop_check(Node *in) const { 1967 // It is unsafe loop if the phi node references itself directly. 1968 if (in == (Node*)this) 1969 return UnsafeLoop; // Unsafe loop 1970 // Unsafe loop if the phi node references itself through an unsafe data node. 1971 // Exclude cases with null inputs or data nodes which could reference 1972 // itself (safe for dead loops). 1973 if (in != nullptr && !in->is_dead_loop_safe()) { 1974 // Check inputs of phi's inputs also. 1975 // It is much less expensive then full graph walk. 1976 uint cnt = in->req(); 1977 uint i = (in->is_Proj() && !in->is_CFG()) ? 0 : 1; 1978 for (; i < cnt; ++i) { 1979 Node* m = in->in(i); 1980 if (m == (Node*)this) 1981 return UnsafeLoop; // Unsafe loop 1982 if (m != nullptr && !m->is_dead_loop_safe()) { 1983 // Check the most common case (about 30% of all cases): 1984 // phi->Load/Store->AddP->(ConP ConP Con)/(Parm Parm Con). 1985 Node *m1 = (m->is_AddP() && m->req() > 3) ? m->in(1) : nullptr; 1986 if (m1 == (Node*)this) 1987 return UnsafeLoop; // Unsafe loop 1988 if (m1 != nullptr && m1 == m->in(2) && 1989 m1->is_dead_loop_safe() && m->in(3)->is_Con()) { 1990 continue; // Safe case 1991 } 1992 // The phi references an unsafe node - need full analysis. 1993 return Unsafe; 1994 } 1995 } 1996 } 1997 return Safe; // Safe case - we can optimize the phi node. 1998 } 1999 2000 //------------------------------is_unsafe_data_reference----------------------- 2001 // If phi can be reached through the data input - it is data loop. 2002 bool PhiNode::is_unsafe_data_reference(Node *in) const { 2003 assert(req() > 1, ""); 2004 // First, check simple cases when phi references itself directly or 2005 // through an other node. 2006 LoopSafety safety = simple_data_loop_check(in); 2007 if (safety == UnsafeLoop) 2008 return true; // phi references itself - unsafe loop 2009 else if (safety == Safe) 2010 return false; // Safe case - phi could be replaced with the unique input. 2011 2012 // Unsafe case when we should go through data graph to determine 2013 // if the phi references itself. 2014 2015 ResourceMark rm; 2016 2017 Node_List nstack; 2018 VectorSet visited; 2019 2020 nstack.push(in); // Start with unique input. 2021 visited.set(in->_idx); 2022 while (nstack.size() != 0) { 2023 Node* n = nstack.pop(); 2024 uint cnt = n->req(); 2025 uint i = (n->is_Proj() && !n->is_CFG()) ? 0 : 1; 2026 for (; i < cnt; i++) { 2027 Node* m = n->in(i); 2028 if (m == (Node*)this) { 2029 return true; // Data loop 2030 } 2031 if (m != nullptr && !m->is_dead_loop_safe()) { // Only look for unsafe cases. 2032 if (!visited.test_set(m->_idx)) 2033 nstack.push(m); 2034 } 2035 } 2036 } 2037 return false; // The phi is not reachable from its inputs 2038 } 2039 2040 // Is this Phi's region or some inputs to the region enqueued for IGVN 2041 // and so could cause the region to be optimized out? 2042 bool PhiNode::wait_for_region_igvn(PhaseGVN* phase) { 2043 PhaseIterGVN* igvn = phase->is_IterGVN(); 2044 Unique_Node_List& worklist = igvn->_worklist; 2045 bool delay = false; 2046 Node* r = in(0); 2047 for (uint j = 1; j < req(); j++) { 2048 Node* rc = r->in(j); 2049 Node* n = in(j); 2050 2051 if (rc == nullptr || !rc->is_Proj()) { continue; } 2052 if (worklist.member(rc)) { 2053 delay = true; 2054 break; 2055 } 2056 2057 if (rc->in(0) == nullptr || !rc->in(0)->is_If()) { continue; } 2058 if (worklist.member(rc->in(0))) { 2059 delay = true; 2060 break; 2061 } 2062 2063 if (rc->in(0)->in(1) == nullptr || !rc->in(0)->in(1)->is_Bool()) { continue; } 2064 if (worklist.member(rc->in(0)->in(1))) { 2065 delay = true; 2066 break; 2067 } 2068 2069 if (rc->in(0)->in(1)->in(1) == nullptr || !rc->in(0)->in(1)->in(1)->is_Cmp()) { continue; } 2070 if (worklist.member(rc->in(0)->in(1)->in(1))) { 2071 delay = true; 2072 break; 2073 } 2074 } 2075 2076 if (delay) { 2077 worklist.push(this); 2078 } 2079 return delay; 2080 } 2081 2082 // Push inline type input nodes (and null) down through the phi recursively (can handle data loops). 2083 InlineTypeNode* PhiNode::push_inline_types_down(PhaseGVN* phase, bool can_reshape, ciInlineKlass* inline_klass) { 2084 assert(inline_klass != nullptr, "must be"); 2085 InlineTypeNode* vt = InlineTypeNode::make_null(*phase, inline_klass, /* transform = */ false)->clone_with_phis(phase, in(0), nullptr, !_type->maybe_null()); 2086 if (can_reshape) { 2087 // Replace phi right away to be able to use the inline 2088 // type node when reaching the phi again through data loops. 2089 PhaseIterGVN* igvn = phase->is_IterGVN(); 2090 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) { 2091 Node* u = fast_out(i); 2092 igvn->rehash_node_delayed(u); 2093 imax -= u->replace_edge(this, vt); 2094 --i; 2095 } 2096 igvn->rehash_node_delayed(this); 2097 assert(outcnt() == 0, "should be dead now"); 2098 } 2099 ResourceMark rm; 2100 Node_List casts; 2101 for (uint i = 1; i < req(); ++i) { 2102 Node* n = in(i); 2103 while (n->is_ConstraintCast()) { 2104 casts.push(n); 2105 n = n->in(1); 2106 } 2107 if (phase->type(n)->is_zero_type()) { 2108 n = InlineTypeNode::make_null(*phase, inline_klass); 2109 } else if (n->is_Phi()) { 2110 assert(can_reshape, "can only handle phis during IGVN"); 2111 n = phase->transform(n->as_Phi()->push_inline_types_down(phase, can_reshape, inline_klass)); 2112 } 2113 while (casts.size() != 0) { 2114 // Push the cast(s) through the InlineTypeNode 2115 // TODO 8302217 Can we avoid cloning? See InlineTypeNode::clone_if_required 2116 Node* cast = casts.pop()->clone(); 2117 cast->set_req_X(1, n->as_InlineType()->get_oop(), phase); 2118 n = n->clone(); 2119 n->as_InlineType()->set_oop(*phase, phase->transform(cast)); 2120 n = phase->transform(n); 2121 } 2122 bool transform = !can_reshape && (i == (req()-1)); // Transform phis on last merge 2123 vt->merge_with(phase, n->as_InlineType(), i, transform); 2124 } 2125 return vt; 2126 } 2127 2128 // If the Phi's Region is in an irreducible loop, and the Region 2129 // has had an input removed, but not yet transformed, it could be 2130 // that the Region (and this Phi) are not reachable from Root. 2131 // If we allow the Phi to collapse before the Region, this may lead 2132 // to dead-loop data. Wait for the Region to check for reachability, 2133 // and potentially remove the dead code. 2134 bool PhiNode::must_wait_for_region_in_irreducible_loop(PhaseGVN* phase) const { 2135 RegionNode* region = in(0)->as_Region(); 2136 if (region->loop_status() == RegionNode::LoopStatus::MaybeIrreducibleEntry) { 2137 Node* top = phase->C->top(); 2138 for (uint j = 1; j < req(); j++) { 2139 Node* rc = region->in(j); // for each control input 2140 if (rc == nullptr || phase->type(rc) == Type::TOP) { 2141 // Region is missing a control input 2142 Node* n = in(j); 2143 if (n != nullptr && n != top) { 2144 // Phi still has its input, so region just lost its input 2145 return true; 2146 } 2147 } 2148 } 2149 } 2150 return false; 2151 } 2152 2153 // Check if splitting a bot memory Phi through a parent MergeMem may lead to 2154 // non-termination. For more details, see comments at the call site in 2155 // PhiNode::Ideal. 2156 bool PhiNode::is_split_through_mergemem_terminating() const { 2157 ResourceMark rm; 2158 VectorSet visited; 2159 GrowableArray<const Node*> worklist; 2160 worklist.push(this); 2161 visited.set(this->_idx); 2162 auto maybe_add_to_worklist = [&](Node* input) { 2163 if (input != nullptr && 2164 (input->is_MergeMem() || input->is_memory_phi()) && 2165 !visited.test_set(input->_idx)) { 2166 worklist.push(input); 2167 assert(input->adr_type() == TypePtr::BOTTOM, 2168 "should only visit bottom memory"); 2169 } 2170 }; 2171 while (worklist.length() > 0) { 2172 const Node* n = worklist.pop(); 2173 if (n->is_MergeMem()) { 2174 Node* input = n->as_MergeMem()->base_memory(); 2175 if (input == this) { 2176 return false; 2177 } 2178 maybe_add_to_worklist(input); 2179 } else { 2180 assert(n->is_memory_phi(), "invariant"); 2181 for (uint i = PhiNode::Input; i < n->req(); i++) { 2182 Node* input = n->in(i); 2183 if (input == this) { 2184 return false; 2185 } 2186 maybe_add_to_worklist(input); 2187 } 2188 } 2189 } 2190 return true; 2191 } 2192 2193 //------------------------------Ideal------------------------------------------ 2194 // Return a node which is more "ideal" than the current node. Must preserve 2195 // the CFG, but we can still strip out dead paths. 2196 Node *PhiNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2197 Node *r = in(0); // RegionNode 2198 assert(r != nullptr && r->is_Region(), "this phi must have a region"); 2199 assert(r->in(0) == nullptr || !r->in(0)->is_Root(), "not a specially hidden merge"); 2200 2201 // Note: During parsing, phis are often transformed before their regions. 2202 // This means we have to use type_or_null to defend against untyped regions. 2203 if( phase->type_or_null(r) == Type::TOP ) // Dead code? 2204 return nullptr; // No change 2205 2206 Node *top = phase->C->top(); 2207 bool new_phi = (outcnt() == 0); // transforming new Phi 2208 // No change for igvn if new phi is not hooked 2209 if (new_phi && can_reshape) 2210 return nullptr; 2211 2212 if (must_wait_for_region_in_irreducible_loop(phase)) { 2213 return nullptr; 2214 } 2215 2216 // The are 2 situations when only one valid phi's input is left 2217 // (in addition to Region input). 2218 // One: region is not loop - replace phi with this input. 2219 // Two: region is loop - replace phi with top since this data path is dead 2220 // and we need to break the dead data loop. 2221 Node* progress = nullptr; // Record if any progress made 2222 for( uint j = 1; j < req(); ++j ){ // For all paths in 2223 // Check unreachable control paths 2224 Node* rc = r->in(j); 2225 Node* n = in(j); // Get the input 2226 if (rc == nullptr || phase->type(rc) == Type::TOP) { 2227 if (n != top) { // Not already top? 2228 PhaseIterGVN *igvn = phase->is_IterGVN(); 2229 if (can_reshape && igvn != nullptr) { 2230 igvn->_worklist.push(r); 2231 } 2232 // Nuke it down 2233 set_req_X(j, top, phase); 2234 progress = this; // Record progress 2235 } 2236 } 2237 } 2238 2239 if (can_reshape && outcnt() == 0) { 2240 // set_req() above may kill outputs if Phi is referenced 2241 // only by itself on the dead (top) control path. 2242 return top; 2243 } 2244 2245 bool uncasted = false; 2246 Node* uin = unique_input(phase, false); 2247 if (uin == nullptr && can_reshape && 2248 // If there is a chance that the region can be optimized out do 2249 // not add a cast node that we can't remove yet. 2250 !wait_for_region_igvn(phase)) { 2251 uncasted = true; 2252 uin = unique_input(phase, true); 2253 } 2254 if (uin == top) { // Simplest case: no alive inputs. 2255 if (can_reshape) // IGVN transformation 2256 return top; 2257 else 2258 return nullptr; // Identity will return TOP 2259 } else if (uin != nullptr) { 2260 // Only one not-null unique input path is left. 2261 // Determine if this input is backedge of a loop. 2262 // (Skip new phis which have no uses and dead regions). 2263 if (outcnt() > 0 && r->in(0) != nullptr) { 2264 if (is_data_loop(r->as_Region(), uin, phase)) { 2265 // Break this data loop to avoid creation of a dead loop. 2266 if (can_reshape) { 2267 return top; 2268 } else { 2269 // We can't return top if we are in Parse phase - cut inputs only 2270 // let Identity to handle the case. 2271 replace_edge(uin, top, phase); 2272 return nullptr; 2273 } 2274 } 2275 } 2276 2277 if (uncasted) { 2278 // Add cast nodes between the phi to be removed and its unique input. 2279 // Wait until after parsing for the type information to propagate from the casts. 2280 assert(can_reshape, "Invalid during parsing"); 2281 const Type* phi_type = bottom_type(); 2282 // Add casts to carry the control dependency of the Phi that is 2283 // going away 2284 Node* cast = nullptr; 2285 const TypeTuple* extra_types = collect_types(phase); 2286 if (phi_type->isa_ptr()) { 2287 const Type* uin_type = phase->type(uin); 2288 if (!phi_type->isa_oopptr() && !uin_type->isa_oopptr()) { 2289 cast = new CastPPNode(r, uin, phi_type, ConstraintCastNode::StrongDependency, extra_types); 2290 } else { 2291 // Use a CastPP for a cast to not null and a CheckCastPP for 2292 // a cast to a new klass (and both if both null-ness and 2293 // klass change). 2294 2295 // If the type of phi is not null but the type of uin may be 2296 // null, uin's type must be casted to not null 2297 if (phi_type->join(TypePtr::NOTNULL) == phi_type->remove_speculative() && 2298 uin_type->join(TypePtr::NOTNULL) != uin_type->remove_speculative()) { 2299 cast = new CastPPNode(r, uin, TypePtr::NOTNULL, ConstraintCastNode::StrongDependency, extra_types); 2300 } 2301 2302 // If the type of phi and uin, both casted to not null, 2303 // differ the klass of uin must be (check)cast'ed to match 2304 // that of phi 2305 if (phi_type->join_speculative(TypePtr::NOTNULL) != uin_type->join_speculative(TypePtr::NOTNULL)) { 2306 Node* n = uin; 2307 if (cast != nullptr) { 2308 cast = phase->transform(cast); 2309 n = cast; 2310 } 2311 cast = new CheckCastPPNode(r, n, phi_type, ConstraintCastNode::StrongDependency, extra_types); 2312 } 2313 if (cast == nullptr) { 2314 cast = new CastPPNode(r, uin, phi_type, ConstraintCastNode::StrongDependency, extra_types); 2315 } 2316 } 2317 } else { 2318 cast = ConstraintCastNode::make_cast_for_type(r, uin, phi_type, ConstraintCastNode::StrongDependency, extra_types); 2319 } 2320 assert(cast != nullptr, "cast should be set"); 2321 cast = phase->transform(cast); 2322 // set all inputs to the new cast(s) so the Phi is removed by Identity 2323 PhaseIterGVN* igvn = phase->is_IterGVN(); 2324 for (uint i = 1; i < req(); i++) { 2325 set_req_X(i, cast, igvn); 2326 } 2327 uin = cast; 2328 } 2329 2330 // One unique input. 2331 debug_only(Node* ident = Identity(phase)); 2332 // The unique input must eventually be detected by the Identity call. 2333 #ifdef ASSERT 2334 if (ident != uin && !ident->is_top() && !must_wait_for_region_in_irreducible_loop(phase)) { 2335 // print this output before failing assert 2336 r->dump(3); 2337 this->dump(3); 2338 ident->dump(); 2339 uin->dump(); 2340 } 2341 #endif 2342 // Identity may not return the expected uin, if it has to wait for the region, in irreducible case 2343 assert(ident == uin || ident->is_top() || must_wait_for_region_in_irreducible_loop(phase), "Identity must clean this up"); 2344 return nullptr; 2345 } 2346 2347 Node* opt = nullptr; 2348 int true_path = is_diamond_phi(); 2349 if (true_path != 0 && 2350 // If one of the diamond's branch is in the process of dying then, the Phi's input for that branch might transform 2351 // to top. If that happens replacing the Phi with an operation that consumes the Phi's inputs will cause the Phi 2352 // to be replaced by top. To prevent that, delay the transformation until the branch has a chance to be removed. 2353 !(can_reshape && wait_for_region_igvn(phase))) { 2354 // Check for CMove'ing identity. If it would be unsafe, 2355 // handle it here. In the safe case, let Identity handle it. 2356 Node* unsafe_id = is_cmove_id(phase, true_path); 2357 if( unsafe_id != nullptr && is_unsafe_data_reference(unsafe_id) ) 2358 opt = unsafe_id; 2359 2360 // Check for simple convert-to-boolean pattern 2361 if( opt == nullptr ) 2362 opt = is_x2logic(phase, this, true_path); 2363 2364 // Check for absolute value 2365 if( opt == nullptr ) 2366 opt = is_absolute(phase, this, true_path); 2367 2368 // Check for conditional add 2369 if( opt == nullptr && can_reshape ) 2370 opt = is_cond_add(phase, this, true_path); 2371 2372 // These 4 optimizations could subsume the phi: 2373 // have to check for a dead data loop creation. 2374 if( opt != nullptr ) { 2375 if( opt == unsafe_id || is_unsafe_data_reference(opt) ) { 2376 // Found dead loop. 2377 if( can_reshape ) 2378 return top; 2379 // We can't return top if we are in Parse phase - cut inputs only 2380 // to stop further optimizations for this phi. Identity will return TOP. 2381 assert(req() == 3, "only diamond merge phi here"); 2382 set_req(1, top); 2383 set_req(2, top); 2384 return nullptr; 2385 } else { 2386 return opt; 2387 } 2388 } 2389 } 2390 2391 // Check for merging identical values and split flow paths 2392 if (can_reshape) { 2393 opt = split_flow_path(phase, this); 2394 // This optimization only modifies phi - don't need to check for dead loop. 2395 assert(opt == nullptr || opt == this, "do not elide phi"); 2396 if (opt != nullptr) return opt; 2397 } 2398 2399 if (in(1) != nullptr && in(1)->Opcode() == Op_AddP && can_reshape) { 2400 // Try to undo Phi of AddP: 2401 // (Phi (AddP base address offset) (AddP base2 address2 offset2)) 2402 // becomes: 2403 // newbase := (Phi base base2) 2404 // newaddress := (Phi address address2) 2405 // newoffset := (Phi offset offset2) 2406 // (AddP newbase newaddress newoffset) 2407 // 2408 // This occurs as a result of unsuccessful split_thru_phi and 2409 // interferes with taking advantage of addressing modes. See the 2410 // clone_shift_expressions code in matcher.cpp 2411 Node* addp = in(1); 2412 Node* base = addp->in(AddPNode::Base); 2413 Node* address = addp->in(AddPNode::Address); 2414 Node* offset = addp->in(AddPNode::Offset); 2415 if (base != nullptr && address != nullptr && offset != nullptr && 2416 !base->is_top() && !address->is_top() && !offset->is_top()) { 2417 const Type* base_type = base->bottom_type(); 2418 const Type* address_type = address->bottom_type(); 2419 // make sure that all the inputs are similar to the first one, 2420 // i.e. AddP with base == address and same offset as first AddP 2421 bool doit = true; 2422 for (uint i = 2; i < req(); i++) { 2423 if (in(i) == nullptr || 2424 in(i)->Opcode() != Op_AddP || 2425 in(i)->in(AddPNode::Base) == nullptr || 2426 in(i)->in(AddPNode::Address) == nullptr || 2427 in(i)->in(AddPNode::Offset) == nullptr || 2428 in(i)->in(AddPNode::Base)->is_top() || 2429 in(i)->in(AddPNode::Address)->is_top() || 2430 in(i)->in(AddPNode::Offset)->is_top()) { 2431 doit = false; 2432 break; 2433 } 2434 if (in(i)->in(AddPNode::Base) != base) { 2435 base = nullptr; 2436 } 2437 if (in(i)->in(AddPNode::Offset) != offset) { 2438 offset = nullptr; 2439 } 2440 if (in(i)->in(AddPNode::Address) != address) { 2441 address = nullptr; 2442 } 2443 // Accumulate type for resulting Phi 2444 base_type = base_type->meet_speculative(in(i)->in(AddPNode::Base)->bottom_type()); 2445 address_type = address_type->meet_speculative(in(i)->in(AddPNode::Address)->bottom_type()); 2446 } 2447 if (doit && base == nullptr) { 2448 // Check for neighboring AddP nodes in a tree. 2449 // If they have a base, use that it. 2450 for (DUIterator_Fast kmax, k = this->fast_outs(kmax); k < kmax; k++) { 2451 Node* u = this->fast_out(k); 2452 if (u->is_AddP()) { 2453 Node* base2 = u->in(AddPNode::Base); 2454 if (base2 != nullptr && !base2->is_top()) { 2455 if (base == nullptr) 2456 base = base2; 2457 else if (base != base2) 2458 { doit = false; break; } 2459 } 2460 } 2461 } 2462 } 2463 if (doit) { 2464 if (base == nullptr) { 2465 base = new PhiNode(in(0), base_type, nullptr); 2466 for (uint i = 1; i < req(); i++) { 2467 base->init_req(i, in(i)->in(AddPNode::Base)); 2468 } 2469 phase->is_IterGVN()->register_new_node_with_optimizer(base); 2470 } 2471 if (address == nullptr) { 2472 address = new PhiNode(in(0), address_type, nullptr); 2473 for (uint i = 1; i < req(); i++) { 2474 address->init_req(i, in(i)->in(AddPNode::Address)); 2475 } 2476 phase->is_IterGVN()->register_new_node_with_optimizer(address); 2477 } 2478 if (offset == nullptr) { 2479 offset = new PhiNode(in(0), TypeX_X, nullptr); 2480 for (uint i = 1; i < req(); i++) { 2481 offset->init_req(i, in(i)->in(AddPNode::Offset)); 2482 } 2483 phase->is_IterGVN()->register_new_node_with_optimizer(offset); 2484 } 2485 return new AddPNode(base, address, offset); 2486 } 2487 } 2488 } 2489 2490 // Split phis through memory merges, so that the memory merges will go away. 2491 // Piggy-back this transformation on the search for a unique input.... 2492 // It will be as if the merged memory is the unique value of the phi. 2493 // (Do not attempt this optimization unless parsing is complete. 2494 // It would make the parser's memory-merge logic sick.) 2495 // (MergeMemNode is not dead_loop_safe - need to check for dead loop.) 2496 if (progress == nullptr && can_reshape && type() == Type::MEMORY) { 2497 2498 // See if this Phi should be sliced. Determine the merge width of input 2499 // MergeMems and check if there is a direct loop to self, as illustrated 2500 // below. 2501 // 2502 // +-------------+ 2503 // | | 2504 // (base_memory) v | 2505 // MergeMem | 2506 // | | 2507 // v | 2508 // Phi (this) | 2509 // | | 2510 // +-----------+ 2511 // 2512 // Generally, there are issues with non-termination with such circularity 2513 // (see comment further below). However, if there is a direct loop to self, 2514 // splitting the Phi through the MergeMem will result in the below. 2515 // 2516 // +---+ 2517 // | | 2518 // v | 2519 // Phi | 2520 // |\ | 2521 // | +-+ 2522 // (base_memory) v 2523 // MergeMem 2524 // 2525 // This split breaks the circularity and consequently does not lead to 2526 // non-termination. 2527 uint merge_width = 0; 2528 // TODO revisit this with JDK-8247216 2529 bool mergemem_only = true; 2530 bool split_always_terminates = false; // Is splitting guaranteed to terminate? 2531 for( uint i=1; i<req(); ++i ) {// For all paths in 2532 Node *ii = in(i); 2533 // TOP inputs should not be counted as safe inputs because if the 2534 // Phi references itself through all other inputs then splitting the 2535 // Phi through memory merges would create dead loop at later stage. 2536 if (ii == top) { 2537 return nullptr; // Delay optimization until graph is cleaned. 2538 } 2539 if (ii->is_MergeMem()) { 2540 MergeMemNode* n = ii->as_MergeMem(); 2541 merge_width = MAX2(merge_width, n->req()); 2542 if (n->base_memory() == this) { 2543 split_always_terminates = true; 2544 } 2545 } else { 2546 mergemem_only = false; 2547 } 2548 } 2549 2550 // There are cases with circular dependencies between bottom Phis 2551 // and MergeMems. Below is a minimal example. 2552 // 2553 // +------------+ 2554 // | | 2555 // (base_memory) v | 2556 // MergeMem | 2557 // | | 2558 // v | 2559 // Phi (this) | 2560 // | | 2561 // v | 2562 // Phi | 2563 // | | 2564 // +----------+ 2565 // 2566 // Here, we cannot break the circularity through a self-loop as there 2567 // are two Phis involved. Repeatedly splitting the Phis through the 2568 // MergeMem leads to non-termination. We check for non-termination below. 2569 // Only check for non-termination if necessary. 2570 if (!mergemem_only && !split_always_terminates && adr_type() == TypePtr::BOTTOM && 2571 merge_width > Compile::AliasIdxRaw) { 2572 split_always_terminates = is_split_through_mergemem_terminating(); 2573 } 2574 2575 if (merge_width > Compile::AliasIdxRaw) { 2576 // found at least one non-empty MergeMem 2577 const TypePtr* at = adr_type(); 2578 if (at != TypePtr::BOTTOM) { 2579 // Patch the existing phi to select an input from the merge: 2580 // Phi:AT1(...MergeMem(m0, m1, m2)...) into 2581 // Phi:AT1(...m1...) 2582 int alias_idx = phase->C->get_alias_index(at); 2583 for (uint i=1; i<req(); ++i) { 2584 Node *ii = in(i); 2585 if (ii->is_MergeMem()) { 2586 MergeMemNode* n = ii->as_MergeMem(); 2587 // compress paths and change unreachable cycles to TOP 2588 // If not, we can update the input infinitely along a MergeMem cycle 2589 // Equivalent code is in MemNode::Ideal_common 2590 Node *m = phase->transform(n); 2591 if (outcnt() == 0) { // Above transform() may kill us! 2592 return top; 2593 } 2594 // If transformed to a MergeMem, get the desired slice 2595 // Otherwise the returned node represents memory for every slice 2596 Node *new_mem = (m->is_MergeMem()) ? 2597 m->as_MergeMem()->memory_at(alias_idx) : m; 2598 // Update input if it is progress over what we have now 2599 if (new_mem != ii) { 2600 set_req_X(i, new_mem, phase->is_IterGVN()); 2601 progress = this; 2602 } 2603 } 2604 } 2605 } else if (mergemem_only || split_always_terminates) { 2606 // If all inputs reference this phi (directly or through data nodes) - 2607 // it is a dead loop. 2608 bool saw_safe_input = false; 2609 for (uint j = 1; j < req(); ++j) { 2610 Node* n = in(j); 2611 if (n->is_MergeMem()) { 2612 MergeMemNode* mm = n->as_MergeMem(); 2613 if (mm->base_memory() == this || mm->base_memory() == mm->empty_memory()) { 2614 // Skip this input if it references back to this phi or if the memory path is dead 2615 continue; 2616 } 2617 } 2618 if (!is_unsafe_data_reference(n)) { 2619 saw_safe_input = true; // found safe input 2620 break; 2621 } 2622 } 2623 if (!saw_safe_input) { 2624 // There is a dead loop: All inputs are either dead or reference back to this phi 2625 return top; 2626 } 2627 2628 // Phi(...MergeMem(m0, m1:AT1, m2:AT2)...) into 2629 // MergeMem(Phi(...m0...), Phi:AT1(...m1...), Phi:AT2(...m2...)) 2630 PhaseIterGVN* igvn = phase->is_IterGVN(); 2631 assert(igvn != nullptr, "sanity check"); 2632 PhiNode* new_base = (PhiNode*) clone(); 2633 // Must eagerly register phis, since they participate in loops. 2634 igvn->register_new_node_with_optimizer(new_base); 2635 2636 MergeMemNode* result = MergeMemNode::make(new_base); 2637 for (uint i = 1; i < req(); ++i) { 2638 Node *ii = in(i); 2639 if (ii->is_MergeMem()) { 2640 MergeMemNode* n = ii->as_MergeMem(); 2641 if (igvn) { 2642 // TODO revisit this with JDK-8247216 2643 // Put 'n' on the worklist because it might be modified by MergeMemStream::iteration_setup 2644 igvn->_worklist.push(n); 2645 } 2646 for (MergeMemStream mms(result, n); mms.next_non_empty2(); ) { 2647 // If we have not seen this slice yet, make a phi for it. 2648 bool made_new_phi = false; 2649 if (mms.is_empty()) { 2650 Node* new_phi = new_base->slice_memory(mms.adr_type(phase->C)); 2651 made_new_phi = true; 2652 igvn->register_new_node_with_optimizer(new_phi); 2653 mms.set_memory(new_phi); 2654 } 2655 Node* phi = mms.memory(); 2656 assert(made_new_phi || phi->in(i) == n, "replace the i-th merge by a slice"); 2657 phi->set_req(i, mms.memory2()); 2658 } 2659 } 2660 } 2661 // Distribute all self-loops. 2662 { // (Extra braces to hide mms.) 2663 for (MergeMemStream mms(result); mms.next_non_empty(); ) { 2664 Node* phi = mms.memory(); 2665 for (uint i = 1; i < req(); ++i) { 2666 if (phi->in(i) == this) phi->set_req(i, phi); 2667 } 2668 } 2669 } 2670 2671 // We could immediately transform the new Phi nodes here, but that can 2672 // result in creating an excessive number of new nodes within a single 2673 // IGVN iteration. We have put the Phi nodes on the IGVN worklist, so 2674 // they are transformed later on in any case. 2675 2676 // Replace self with the result. 2677 return result; 2678 } 2679 } 2680 // 2681 // Other optimizations on the memory chain 2682 // 2683 const TypePtr* at = adr_type(); 2684 for( uint i=1; i<req(); ++i ) {// For all paths in 2685 Node *ii = in(i); 2686 Node *new_in = MemNode::optimize_memory_chain(ii, at, nullptr, phase); 2687 if (ii != new_in ) { 2688 set_req(i, new_in); 2689 progress = this; 2690 } 2691 } 2692 } 2693 2694 #ifdef _LP64 2695 // Push DecodeN/DecodeNKlass down through phi. 2696 // The rest of phi graph will transform by split EncodeP node though phis up. 2697 if ((UseCompressedOops || UseCompressedClassPointers) && can_reshape && progress == nullptr) { 2698 bool may_push = true; 2699 bool has_decodeN = false; 2700 bool is_decodeN = false; 2701 for (uint i=1; i<req(); ++i) {// For all paths in 2702 Node *ii = in(i); 2703 if (ii->is_DecodeNarrowPtr() && ii->bottom_type() == bottom_type()) { 2704 // Do optimization if a non dead path exist. 2705 if (ii->in(1)->bottom_type() != Type::TOP) { 2706 has_decodeN = true; 2707 is_decodeN = ii->is_DecodeN(); 2708 } 2709 } else if (!ii->is_Phi()) { 2710 may_push = false; 2711 } 2712 } 2713 2714 if (has_decodeN && may_push) { 2715 PhaseIterGVN *igvn = phase->is_IterGVN(); 2716 // Make narrow type for new phi. 2717 const Type* narrow_t; 2718 if (is_decodeN) { 2719 narrow_t = TypeNarrowOop::make(this->bottom_type()->is_ptr()); 2720 } else { 2721 narrow_t = TypeNarrowKlass::make(this->bottom_type()->is_ptr()); 2722 } 2723 PhiNode* new_phi = new PhiNode(r, narrow_t); 2724 uint orig_cnt = req(); 2725 for (uint i=1; i<req(); ++i) {// For all paths in 2726 Node *ii = in(i); 2727 Node* new_ii = nullptr; 2728 if (ii->is_DecodeNarrowPtr()) { 2729 assert(ii->bottom_type() == bottom_type(), "sanity"); 2730 new_ii = ii->in(1); 2731 } else { 2732 assert(ii->is_Phi(), "sanity"); 2733 if (ii->as_Phi() == this) { 2734 new_ii = new_phi; 2735 } else { 2736 if (is_decodeN) { 2737 new_ii = new EncodePNode(ii, narrow_t); 2738 } else { 2739 new_ii = new EncodePKlassNode(ii, narrow_t); 2740 } 2741 igvn->register_new_node_with_optimizer(new_ii); 2742 } 2743 } 2744 new_phi->set_req(i, new_ii); 2745 } 2746 igvn->register_new_node_with_optimizer(new_phi, this); 2747 if (is_decodeN) { 2748 progress = new DecodeNNode(new_phi, bottom_type()); 2749 } else { 2750 progress = new DecodeNKlassNode(new_phi, bottom_type()); 2751 } 2752 } 2753 } 2754 #endif 2755 2756 Node* inline_type = try_push_inline_types_down(phase, can_reshape); 2757 if (inline_type != this) { 2758 return inline_type; 2759 } 2760 2761 // Try to convert a Phi with two duplicated convert nodes into a phi of the pre-conversion type and the convert node 2762 // proceeding the phi, to de-duplicate the convert node and compact the IR. 2763 if (can_reshape && progress == nullptr) { 2764 ConvertNode* convert = in(1)->isa_Convert(); 2765 if (convert != nullptr) { 2766 int conv_op = convert->Opcode(); 2767 bool ok = true; 2768 2769 // Check the rest of the inputs 2770 for (uint i = 2; i < req(); i++) { 2771 // Make sure that all inputs are of the same type of convert node 2772 if (in(i)->Opcode() != conv_op) { 2773 ok = false; 2774 break; 2775 } 2776 } 2777 2778 if (ok) { 2779 // Find the local bottom type to set as the type of the phi 2780 const Type* source_type = Type::get_const_basic_type(convert->in_type()->basic_type()); 2781 const Type* dest_type = convert->bottom_type(); 2782 2783 PhiNode* newphi = new PhiNode(in(0), source_type, nullptr); 2784 // Set inputs to the new phi be the inputs of the convert 2785 for (uint i = 1; i < req(); i++) { 2786 newphi->init_req(i, in(i)->in(1)); 2787 } 2788 2789 phase->is_IterGVN()->register_new_node_with_optimizer(newphi, this); 2790 2791 return ConvertNode::create_convert(get_convert_type(convert, source_type), get_convert_type(convert, dest_type), newphi); 2792 } 2793 } 2794 } 2795 2796 // Phi (VB ... VB) => VB (Phi ...) (Phi ...) 2797 if (EnableVectorReboxing && can_reshape && progress == nullptr && type()->isa_oopptr()) { 2798 progress = merge_through_phi(this, phase->is_IterGVN()); 2799 } 2800 2801 return progress; // Return any progress 2802 } 2803 2804 // Check recursively if inputs are either an inline type, constant null 2805 // or another Phi (including self references through data loops). If so, 2806 // push the inline types down through the phis to enable folding of loads. 2807 Node* PhiNode::try_push_inline_types_down(PhaseGVN* phase, const bool can_reshape) { 2808 if (!can_be_inline_type()) { 2809 return this; 2810 } 2811 2812 ciInlineKlass* inline_klass; 2813 if (can_push_inline_types_down(phase, can_reshape, inline_klass)) { 2814 assert(inline_klass != nullptr, "must be"); 2815 return push_inline_types_down(phase, can_reshape, inline_klass); 2816 } 2817 return this; 2818 } 2819 2820 bool PhiNode::can_push_inline_types_down(PhaseGVN* phase, const bool can_reshape, ciInlineKlass*& inline_klass) { 2821 if (req() <= 2) { 2822 // Dead phi. 2823 return false; 2824 } 2825 inline_klass = nullptr; 2826 2827 // TODO 8302217 We need to prevent endless pushing through 2828 bool only_phi = (outcnt() != 0); 2829 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) { 2830 Node* n = fast_out(i); 2831 if (n->is_InlineType() && n->in(1) == this) { 2832 return false; 2833 } 2834 if (!n->is_Phi()) { 2835 only_phi = false; 2836 } 2837 } 2838 if (only_phi) { 2839 return false; 2840 } 2841 2842 ResourceMark rm; 2843 Unique_Node_List worklist; 2844 worklist.push(this); 2845 Node_List casts; 2846 2847 for (uint next = 0; next < worklist.size(); next++) { 2848 Node* phi = worklist.at(next); 2849 for (uint i = 1; i < phi->req(); i++) { 2850 Node* n = phi->in(i); 2851 if (n == nullptr) { 2852 return false; 2853 } 2854 while (n->is_ConstraintCast()) { 2855 if (n->in(0) != nullptr && n->in(0)->is_top()) { 2856 // Will die, don't optimize 2857 return false; 2858 } 2859 casts.push(n); 2860 n = n->in(1); 2861 } 2862 const Type* type = phase->type(n); 2863 if (n->is_InlineType() && (inline_klass == nullptr || inline_klass == type->inline_klass())) { 2864 inline_klass = type->inline_klass(); 2865 } else if (n->is_Phi() && can_reshape && n->bottom_type()->isa_ptr()) { 2866 worklist.push(n); 2867 } else if (!type->is_zero_type()) { 2868 return false; 2869 } 2870 } 2871 } 2872 if (inline_klass == nullptr) { 2873 return false; 2874 } 2875 2876 // Check if cast nodes can be pushed through 2877 const Type* t = Type::get_const_type(inline_klass); 2878 while (casts.size() != 0 && t != nullptr) { 2879 Node* cast = casts.pop(); 2880 if (t->filter(cast->bottom_type()) == Type::TOP) { 2881 return false; 2882 } 2883 } 2884 2885 return true; 2886 } 2887 2888 #ifdef ASSERT 2889 bool PhiNode::can_push_inline_types_down(PhaseGVN* phase) { 2890 if (!can_be_inline_type()) { 2891 return false; 2892 } 2893 2894 ciInlineKlass* inline_klass; 2895 return can_push_inline_types_down(phase, true, inline_klass); 2896 } 2897 #endif // ASSERT 2898 2899 static int compare_types(const Type* const& e1, const Type* const& e2) { 2900 return (intptr_t)e1 - (intptr_t)e2; 2901 } 2902 2903 // Collect types at casts that are going to be eliminated at that Phi and store them in a TypeTuple. 2904 // Sort the types using an arbitrary order so a list of some types always hashes to the same TypeTuple (and TypeTuple 2905 // pointer comparison is enough to tell if 2 list of types are the same or not) 2906 const TypeTuple* PhiNode::collect_types(PhaseGVN* phase) const { 2907 const Node* region = in(0); 2908 const Type* phi_type = bottom_type(); 2909 ResourceMark rm; 2910 GrowableArray<const Type*> types; 2911 for (uint i = 1; i < req(); i++) { 2912 if (region->in(i) == nullptr || phase->type(region->in(i)) == Type::TOP) { 2913 continue; 2914 } 2915 Node* in = Node::in(i); 2916 const Type* t = phase->type(in); 2917 if (in == nullptr || in == this || t == Type::TOP) { 2918 continue; 2919 } 2920 if (t != phi_type && t->higher_equal_speculative(phi_type)) { 2921 types.insert_sorted<compare_types>(t); 2922 } 2923 while (in != nullptr && in->is_ConstraintCast()) { 2924 Node* next = in->in(1); 2925 if (phase->type(next)->isa_rawptr() && phase->type(in)->isa_oopptr()) { 2926 break; 2927 } 2928 ConstraintCastNode* cast = in->as_ConstraintCast(); 2929 for (int j = 0; j < cast->extra_types_count(); ++j) { 2930 const Type* extra_t = cast->extra_type_at(j); 2931 if (extra_t != phi_type && extra_t->higher_equal_speculative(phi_type)) { 2932 types.insert_sorted<compare_types>(extra_t); 2933 } 2934 } 2935 in = next; 2936 } 2937 } 2938 const Type **flds = (const Type **)(phase->C->type_arena()->AmallocWords(types.length()*sizeof(Type*))); 2939 for (int i = 0; i < types.length(); ++i) { 2940 flds[i] = types.at(i); 2941 } 2942 return TypeTuple::make(types.length(), flds); 2943 } 2944 2945 Node* PhiNode::clone_through_phi(Node* root_phi, const Type* t, uint c, PhaseIterGVN* igvn) { 2946 Node_Stack stack(1); 2947 VectorSet visited; 2948 Node_List node_map; 2949 2950 stack.push(root_phi, 1); // ignore control 2951 visited.set(root_phi->_idx); 2952 2953 Node* new_phi = new PhiNode(root_phi->in(0), t); 2954 node_map.map(root_phi->_idx, new_phi); 2955 2956 while (stack.is_nonempty()) { 2957 Node* n = stack.node(); 2958 uint idx = stack.index(); 2959 assert(n->is_Phi(), "not a phi"); 2960 if (idx < n->req()) { 2961 stack.set_index(idx + 1); 2962 Node* def = n->in(idx); 2963 if (def == nullptr) { 2964 continue; // ignore dead path 2965 } else if (def->is_Phi()) { // inner node 2966 Node* new_phi = node_map[n->_idx]; 2967 if (!visited.test_set(def->_idx)) { // not visited yet 2968 node_map.map(def->_idx, new PhiNode(def->in(0), t)); 2969 stack.push(def, 1); // ignore control 2970 } 2971 Node* new_in = node_map[def->_idx]; 2972 new_phi->set_req(idx, new_in); 2973 } else if (def->Opcode() == Op_VectorBox) { // leaf 2974 assert(n->is_Phi(), "not a phi"); 2975 Node* new_phi = node_map[n->_idx]; 2976 new_phi->set_req(idx, def->in(c)); 2977 } else { 2978 assert(false, "not optimizeable"); 2979 return nullptr; 2980 } 2981 } else { 2982 Node* new_phi = node_map[n->_idx]; 2983 igvn->register_new_node_with_optimizer(new_phi, n); 2984 stack.pop(); 2985 } 2986 } 2987 return new_phi; 2988 } 2989 2990 Node* PhiNode::merge_through_phi(Node* root_phi, PhaseIterGVN* igvn) { 2991 Node_Stack stack(1); 2992 VectorSet visited; 2993 2994 stack.push(root_phi, 1); // ignore control 2995 visited.set(root_phi->_idx); 2996 2997 VectorBoxNode* cached_vbox = nullptr; 2998 while (stack.is_nonempty()) { 2999 Node* n = stack.node(); 3000 uint idx = stack.index(); 3001 if (idx < n->req()) { 3002 stack.set_index(idx + 1); 3003 Node* in = n->in(idx); 3004 if (in == nullptr) { 3005 continue; // ignore dead path 3006 } else if (in->isa_Phi()) { 3007 if (!visited.test_set(in->_idx)) { 3008 stack.push(in, 1); // ignore control 3009 } 3010 } else if (in->Opcode() == Op_VectorBox) { 3011 VectorBoxNode* vbox = static_cast<VectorBoxNode*>(in); 3012 if (cached_vbox == nullptr) { 3013 cached_vbox = vbox; 3014 } else if (vbox->vec_type() != cached_vbox->vec_type()) { 3015 // TODO: vector type mismatch can be handled with additional reinterpret casts 3016 assert(!Type::equals(vbox->vec_type(), cached_vbox->vec_type()), "inconsistent"); 3017 return nullptr; // not optimizable: vector type mismatch 3018 } else if (vbox->box_type() != cached_vbox->box_type()) { 3019 assert(!Type::equals(vbox->box_type(), cached_vbox->box_type()), "inconsistent"); 3020 return nullptr; // not optimizable: box type mismatch 3021 } 3022 } else { 3023 return nullptr; // not optimizable: neither Phi nor VectorBox 3024 } 3025 } else { 3026 stack.pop(); 3027 } 3028 } 3029 if (cached_vbox == nullptr) { 3030 // We have a Phi dead-loop (no data-input). Phi nodes are considered safe, 3031 // so just avoid this optimization. 3032 return nullptr; 3033 } 3034 const TypeInstPtr* btype = cached_vbox->box_type(); 3035 const TypeVect* vtype = cached_vbox->vec_type(); 3036 Node* new_vbox_phi = clone_through_phi(root_phi, btype, VectorBoxNode::Box, igvn); 3037 Node* new_vect_phi = clone_through_phi(root_phi, vtype, VectorBoxNode::Value, igvn); 3038 return new VectorBoxNode(igvn->C, new_vbox_phi, new_vect_phi, btype, vtype); 3039 } 3040 3041 bool PhiNode::is_data_loop(RegionNode* r, Node* uin, const PhaseGVN* phase) { 3042 // First, take the short cut when we know it is a loop and the EntryControl data path is dead. 3043 // The loop node may only have one input because the entry path was removed in PhaseIdealLoop::Dominators(). 3044 // Then, check if there is a data loop when the phi references itself directly or through other data nodes. 3045 assert(!r->is_Loop() || r->req() <= 3, "Loop node should have 3 or less inputs"); 3046 const bool is_loop = (r->is_Loop() && r->req() == 3); 3047 const Node* top = phase->C->top(); 3048 if (is_loop) { 3049 return !uin->eqv_uncast(in(LoopNode::EntryControl)); 3050 } else { 3051 // We have a data loop either with an unsafe data reference or if a region is unreachable. 3052 return is_unsafe_data_reference(uin) 3053 || (r->req() == 3 && (r->in(1) != top && r->in(2) == top && r->is_unreachable_region(phase))); 3054 } 3055 } 3056 3057 //------------------------------is_tripcount----------------------------------- 3058 bool PhiNode::is_tripcount(BasicType bt) const { 3059 return (in(0) != nullptr && in(0)->is_BaseCountedLoop() && 3060 in(0)->as_BaseCountedLoop()->bt() == bt && 3061 in(0)->as_BaseCountedLoop()->phi() == this); 3062 } 3063 3064 //------------------------------out_RegMask------------------------------------ 3065 const RegMask &PhiNode::in_RegMask(uint i) const { 3066 return i ? out_RegMask() : RegMask::Empty; 3067 } 3068 3069 const RegMask &PhiNode::out_RegMask() const { 3070 uint ideal_reg = _type->ideal_reg(); 3071 assert( ideal_reg != Node::NotAMachineReg, "invalid type at Phi" ); 3072 if( ideal_reg == 0 ) return RegMask::Empty; 3073 assert(ideal_reg != Op_RegFlags, "flags register is not spillable"); 3074 return *(Compile::current()->matcher()->idealreg2spillmask[ideal_reg]); 3075 } 3076 3077 #ifndef PRODUCT 3078 void PhiNode::dump_spec(outputStream *st) const { 3079 TypeNode::dump_spec(st); 3080 if (is_tripcount(T_INT) || is_tripcount(T_LONG)) { 3081 st->print(" #tripcount"); 3082 } 3083 } 3084 #endif 3085 3086 3087 //============================================================================= 3088 const Type* GotoNode::Value(PhaseGVN* phase) const { 3089 // If the input is reachable, then we are executed. 3090 // If the input is not reachable, then we are not executed. 3091 return phase->type(in(0)); 3092 } 3093 3094 Node* GotoNode::Identity(PhaseGVN* phase) { 3095 return in(0); // Simple copy of incoming control 3096 } 3097 3098 const RegMask &GotoNode::out_RegMask() const { 3099 return RegMask::Empty; 3100 } 3101 3102 //============================================================================= 3103 const RegMask &JumpNode::out_RegMask() const { 3104 return RegMask::Empty; 3105 } 3106 3107 //============================================================================= 3108 const RegMask &JProjNode::out_RegMask() const { 3109 return RegMask::Empty; 3110 } 3111 3112 //============================================================================= 3113 const RegMask &CProjNode::out_RegMask() const { 3114 return RegMask::Empty; 3115 } 3116 3117 3118 3119 //============================================================================= 3120 3121 uint PCTableNode::hash() const { return Node::hash() + _size; } 3122 bool PCTableNode::cmp( const Node &n ) const 3123 { return _size == ((PCTableNode&)n)._size; } 3124 3125 const Type *PCTableNode::bottom_type() const { 3126 const Type** f = TypeTuple::fields(_size); 3127 for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL; 3128 return TypeTuple::make(_size, f); 3129 } 3130 3131 //------------------------------Value------------------------------------------ 3132 // Compute the type of the PCTableNode. If reachable it is a tuple of 3133 // Control, otherwise the table targets are not reachable 3134 const Type* PCTableNode::Value(PhaseGVN* phase) const { 3135 if( phase->type(in(0)) == Type::CONTROL ) 3136 return bottom_type(); 3137 return Type::TOP; // All paths dead? Then so are we 3138 } 3139 3140 //------------------------------Ideal------------------------------------------ 3141 // Return a node which is more "ideal" than the current node. Strip out 3142 // control copies 3143 Node *PCTableNode::Ideal(PhaseGVN *phase, bool can_reshape) { 3144 return remove_dead_region(phase, can_reshape) ? this : nullptr; 3145 } 3146 3147 //============================================================================= 3148 uint JumpProjNode::hash() const { 3149 return Node::hash() + _dest_bci; 3150 } 3151 3152 bool JumpProjNode::cmp( const Node &n ) const { 3153 return ProjNode::cmp(n) && 3154 _dest_bci == ((JumpProjNode&)n)._dest_bci; 3155 } 3156 3157 #ifndef PRODUCT 3158 void JumpProjNode::dump_spec(outputStream *st) const { 3159 ProjNode::dump_spec(st); 3160 st->print("@bci %d ",_dest_bci); 3161 } 3162 3163 void JumpProjNode::dump_compact_spec(outputStream *st) const { 3164 ProjNode::dump_compact_spec(st); 3165 st->print("(%d)%d@%d", _switch_val, _proj_no, _dest_bci); 3166 } 3167 #endif 3168 3169 //============================================================================= 3170 //------------------------------Value------------------------------------------ 3171 // Check for being unreachable, or for coming from a Rethrow. Rethrow's cannot 3172 // have the default "fall_through_index" path. 3173 const Type* CatchNode::Value(PhaseGVN* phase) const { 3174 // Unreachable? Then so are all paths from here. 3175 if( phase->type(in(0)) == Type::TOP ) return Type::TOP; 3176 // First assume all paths are reachable 3177 const Type** f = TypeTuple::fields(_size); 3178 for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL; 3179 // Identify cases that will always throw an exception 3180 // () rethrow call 3181 // () virtual or interface call with null receiver 3182 // () call is a check cast with incompatible arguments 3183 if( in(1)->is_Proj() ) { 3184 Node *i10 = in(1)->in(0); 3185 if( i10->is_Call() ) { 3186 CallNode *call = i10->as_Call(); 3187 // Rethrows always throw exceptions, never return 3188 if (call->entry_point() == OptoRuntime::rethrow_stub()) { 3189 f[CatchProjNode::fall_through_index] = Type::TOP; 3190 } else if (call->is_AllocateArray()) { 3191 Node* klass_node = call->in(AllocateNode::KlassNode); 3192 Node* length = call->in(AllocateNode::ALength); 3193 const Type* length_type = phase->type(length); 3194 const Type* klass_type = phase->type(klass_node); 3195 Node* valid_length_test = call->in(AllocateNode::ValidLengthTest); 3196 const Type* valid_length_test_t = phase->type(valid_length_test); 3197 if (length_type == Type::TOP || klass_type == Type::TOP || valid_length_test_t == Type::TOP || 3198 valid_length_test_t->is_int()->is_con(0)) { 3199 f[CatchProjNode::fall_through_index] = Type::TOP; 3200 } 3201 } else if( call->req() > TypeFunc::Parms ) { 3202 const Type *arg0 = phase->type( call->in(TypeFunc::Parms) ); 3203 // Check for null receiver to virtual or interface calls 3204 if( call->is_CallDynamicJava() && 3205 arg0->higher_equal(TypePtr::NULL_PTR) ) { 3206 f[CatchProjNode::fall_through_index] = Type::TOP; 3207 } 3208 } // End of if not a runtime stub 3209 } // End of if have call above me 3210 } // End of slot 1 is not a projection 3211 return TypeTuple::make(_size, f); 3212 } 3213 3214 //============================================================================= 3215 uint CatchProjNode::hash() const { 3216 return Node::hash() + _handler_bci; 3217 } 3218 3219 3220 bool CatchProjNode::cmp( const Node &n ) const { 3221 return ProjNode::cmp(n) && 3222 _handler_bci == ((CatchProjNode&)n)._handler_bci; 3223 } 3224 3225 3226 //------------------------------Identity--------------------------------------- 3227 // If only 1 target is possible, choose it if it is the main control 3228 Node* CatchProjNode::Identity(PhaseGVN* phase) { 3229 // If my value is control and no other value is, then treat as ID 3230 const TypeTuple *t = phase->type(in(0))->is_tuple(); 3231 if (t->field_at(_con) != Type::CONTROL) return this; 3232 // If we remove the last CatchProj and elide the Catch/CatchProj, then we 3233 // also remove any exception table entry. Thus we must know the call 3234 // feeding the Catch will not really throw an exception. This is ok for 3235 // the main fall-thru control (happens when we know a call can never throw 3236 // an exception) or for "rethrow", because a further optimization will 3237 // yank the rethrow (happens when we inline a function that can throw an 3238 // exception and the caller has no handler). Not legal, e.g., for passing 3239 // a null receiver to a v-call, or passing bad types to a slow-check-cast. 3240 // These cases MUST throw an exception via the runtime system, so the VM 3241 // will be looking for a table entry. 3242 Node *proj = in(0)->in(1); // Expect a proj feeding CatchNode 3243 CallNode *call; 3244 if (_con != TypeFunc::Control && // Bail out if not the main control. 3245 !(proj->is_Proj() && // AND NOT a rethrow 3246 proj->in(0)->is_Call() && 3247 (call = proj->in(0)->as_Call()) && 3248 call->entry_point() == OptoRuntime::rethrow_stub())) 3249 return this; 3250 3251 // Search for any other path being control 3252 for (uint i = 0; i < t->cnt(); i++) { 3253 if (i != _con && t->field_at(i) == Type::CONTROL) 3254 return this; 3255 } 3256 // Only my path is possible; I am identity on control to the jump 3257 return in(0)->in(0); 3258 } 3259 3260 3261 #ifndef PRODUCT 3262 void CatchProjNode::dump_spec(outputStream *st) const { 3263 ProjNode::dump_spec(st); 3264 st->print("@bci %d ",_handler_bci); 3265 } 3266 #endif 3267 3268 //============================================================================= 3269 //------------------------------Identity--------------------------------------- 3270 // Check for CreateEx being Identity. 3271 Node* CreateExNode::Identity(PhaseGVN* phase) { 3272 if( phase->type(in(1)) == Type::TOP ) return in(1); 3273 if( phase->type(in(0)) == Type::TOP ) return in(0); 3274 if (phase->type(in(0)->in(0)) == Type::TOP) { 3275 assert(in(0)->is_CatchProj(), "control is CatchProj"); 3276 return phase->C->top(); // dead code 3277 } 3278 // We only come from CatchProj, unless the CatchProj goes away. 3279 // If the CatchProj is optimized away, then we just carry the 3280 // exception oop through. 3281 3282 // CheckCastPPNode::Ideal() for inline types reuses the exception 3283 // paths of a call to perform an allocation: we can see a Phi here. 3284 if (in(1)->is_Phi()) { 3285 return this; 3286 } 3287 CallNode *call = in(1)->in(0)->as_Call(); 3288 3289 return (in(0)->is_CatchProj() && in(0)->in(0)->is_Catch() && 3290 in(0)->in(0)->in(1) == in(1)) ? this : call->in(TypeFunc::Parms); 3291 } 3292 3293 //============================================================================= 3294 //------------------------------Value------------------------------------------ 3295 // Check for being unreachable. 3296 const Type* NeverBranchNode::Value(PhaseGVN* phase) const { 3297 if (!in(0) || in(0)->is_top()) return Type::TOP; 3298 return bottom_type(); 3299 } 3300 3301 //------------------------------Ideal------------------------------------------ 3302 // Check for no longer being part of a loop 3303 Node *NeverBranchNode::Ideal(PhaseGVN *phase, bool can_reshape) { 3304 if (can_reshape && !in(0)->is_Region()) { 3305 // Dead code elimination can sometimes delete this projection so 3306 // if it's not there, there's nothing to do. 3307 Node* fallthru = proj_out_or_null(0); 3308 if (fallthru != nullptr) { 3309 phase->is_IterGVN()->replace_node(fallthru, in(0)); 3310 } 3311 return phase->C->top(); 3312 } 3313 return nullptr; 3314 } 3315 3316 #ifndef PRODUCT 3317 void NeverBranchNode::format( PhaseRegAlloc *ra_, outputStream *st) const { 3318 st->print("%s", Name()); 3319 } 3320 #endif 3321 3322 Node* BlackholeNode::Ideal(PhaseGVN* phase, bool can_reshape) { 3323 return remove_dead_region(phase, can_reshape) ? this : nullptr; 3324 } 3325 3326 #ifndef PRODUCT 3327 void BlackholeNode::format(PhaseRegAlloc* ra, outputStream* st) const { 3328 st->print("blackhole "); 3329 bool first = true; 3330 for (uint i = 0; i < req(); i++) { 3331 Node* n = in(i); 3332 if (n != nullptr && OptoReg::is_valid(ra->get_reg_first(n))) { 3333 if (first) { 3334 first = false; 3335 } else { 3336 st->print(", "); 3337 } 3338 char buf[128]; 3339 ra->dump_register(n, buf, sizeof(buf)); 3340 st->print("%s", buf); 3341 } 3342 } 3343 st->cr(); 3344 } 3345 #endif 3346