1 /* 2 * Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "ci/ciTypeFlow.hpp" 27 #include "memory/allocation.inline.hpp" 28 #include "memory/resourceArea.hpp" 29 #include "opto/addnode.hpp" 30 #include "opto/castnode.hpp" 31 #include "opto/cfgnode.hpp" 32 #include "opto/connode.hpp" 33 #include "opto/loopnode.hpp" 34 #include "opto/phaseX.hpp" 35 #include "opto/runtime.hpp" 36 #include "opto/rootnode.hpp" 37 #include "opto/subnode.hpp" 38 39 // Portions of code courtesy of Clifford Click 40 41 // Optimization - Graph Style 42 43 44 #ifndef PRODUCT 45 extern int explicit_null_checks_elided; 46 #endif 47 48 //============================================================================= 49 //------------------------------Value------------------------------------------ 50 // Return a tuple for whichever arm of the IF is reachable 51 const Type* IfNode::Value(PhaseGVN* phase) const { 52 if( !in(0) ) return Type::TOP; 53 if( phase->type(in(0)) == Type::TOP ) 54 return Type::TOP; 55 const Type *t = phase->type(in(1)); 56 if( t == Type::TOP ) // data is undefined 57 return TypeTuple::IFNEITHER; // unreachable altogether 58 if( t == TypeInt::ZERO ) // zero, or false 59 return TypeTuple::IFFALSE; // only false branch is reachable 60 if( t == TypeInt::ONE ) // 1, or true 61 return TypeTuple::IFTRUE; // only true branch is reachable 62 assert( t == TypeInt::BOOL, "expected boolean type" ); 63 64 return TypeTuple::IFBOTH; // No progress 65 } 66 67 const RegMask &IfNode::out_RegMask() const { 68 return RegMask::Empty; 69 } 70 71 //------------------------------split_if--------------------------------------- 72 // Look for places where we merge constants, then test on the merged value. 73 // If the IF test will be constant folded on the path with the constant, we 74 // win by splitting the IF to before the merge point. 75 static Node* split_if(IfNode *iff, PhaseIterGVN *igvn) { 76 // I could be a lot more general here, but I'm trying to squeeze this 77 // in before the Christmas '98 break so I'm gonna be kinda restrictive 78 // on the patterns I accept. CNC 79 80 // Look for a compare of a constant and a merged value 81 Node *i1 = iff->in(1); 82 if( !i1->is_Bool() ) return NULL; 83 BoolNode *b = i1->as_Bool(); 84 Node *cmp = b->in(1); 85 if( !cmp->is_Cmp() ) return NULL; 86 i1 = cmp->in(1); 87 if( i1 == NULL || !i1->is_Phi() ) return NULL; 88 PhiNode *phi = i1->as_Phi(); 89 if( phi->is_copy() ) return NULL; 90 Node *con2 = cmp->in(2); 91 if( !con2->is_Con() ) return NULL; 92 // See that the merge point contains some constants 93 Node *con1=NULL; 94 uint i4; 95 for( i4 = 1; i4 < phi->req(); i4++ ) { 96 con1 = phi->in(i4); 97 if( !con1 ) return NULL; // Do not optimize partially collapsed merges 98 if( con1->is_Con() ) break; // Found a constant 99 // Also allow null-vs-not-null checks 100 const TypePtr *tp = igvn->type(con1)->isa_ptr(); 101 if( tp && tp->_ptr == TypePtr::NotNull ) 102 break; 103 } 104 if( i4 >= phi->req() ) return NULL; // Found no constants 105 106 igvn->C->set_has_split_ifs(true); // Has chance for split-if 107 108 // Make sure that the compare can be constant folded away 109 Node *cmp2 = cmp->clone(); 110 cmp2->set_req(1,con1); 111 cmp2->set_req(2,con2); 112 const Type *t = cmp2->Value(igvn); 113 // This compare is dead, so whack it! 114 igvn->remove_dead_node(cmp2); 115 if( !t->singleton() ) return NULL; 116 117 // No intervening control, like a simple Call 118 Node *r = iff->in(0); 119 if( !r->is_Region() ) return NULL; 120 if (r->is_Loop() && r->in(LoopNode::LoopBackControl)->is_top()) return NULL; // going away anyway 121 if( phi->region() != r ) return NULL; 122 // No other users of the cmp/bool 123 if (b->outcnt() != 1 || cmp->outcnt() != 1) { 124 //tty->print_cr("many users of cmp/bool"); 125 return NULL; 126 } 127 128 // Make sure we can determine where all the uses of merged values go 129 for (DUIterator_Fast jmax, j = r->fast_outs(jmax); j < jmax; j++) { 130 Node* u = r->fast_out(j); 131 if( u == r ) continue; 132 if( u == iff ) continue; 133 if( u->outcnt() == 0 ) continue; // use is dead & ignorable 134 if( !u->is_Phi() ) { 135 /* 136 if( u->is_Start() ) { 137 tty->print_cr("Region has inlined start use"); 138 } else { 139 tty->print_cr("Region has odd use"); 140 u->dump(2); 141 }*/ 142 return NULL; 143 } 144 if( u != phi ) { 145 // CNC - do not allow any other merged value 146 //tty->print_cr("Merging another value"); 147 //u->dump(2); 148 return NULL; 149 } 150 // Make sure we can account for all Phi uses 151 for (DUIterator_Fast kmax, k = u->fast_outs(kmax); k < kmax; k++) { 152 Node* v = u->fast_out(k); // User of the phi 153 // CNC - Allow only really simple patterns. 154 // In particular I disallow AddP of the Phi, a fairly common pattern 155 if (v == cmp) continue; // The compare is OK 156 if (v->is_ConstraintCast()) { 157 // If the cast is derived from data flow edges, it may not have a control edge. 158 // If so, it should be safe to split. But follow-up code can not deal with 159 // this (l. 359). So skip. 160 if (v->in(0) == NULL) { 161 return NULL; 162 } 163 if (v->in(0)->in(0) == iff) { 164 continue; // CastPP/II of the IfNode is OK 165 } 166 } 167 // Disabled following code because I cannot tell if exactly one 168 // path dominates without a real dominator check. CNC 9/9/1999 169 //uint vop = v->Opcode(); 170 //if( vop == Op_Phi ) { // Phi from another merge point might be OK 171 // Node *r = v->in(0); // Get controlling point 172 // if( !r ) return NULL; // Degraded to a copy 173 // // Find exactly one path in (either True or False doms, but not IFF) 174 // int cnt = 0; 175 // for( uint i = 1; i < r->req(); i++ ) 176 // if( r->in(i) && r->in(i)->in(0) == iff ) 177 // cnt++; 178 // if( cnt == 1 ) continue; // Exactly one of True or False guards Phi 179 //} 180 if( !v->is_Call() ) { 181 /* 182 if( v->Opcode() == Op_AddP ) { 183 tty->print_cr("Phi has AddP use"); 184 } else if( v->Opcode() == Op_CastPP ) { 185 tty->print_cr("Phi has CastPP use"); 186 } else if( v->Opcode() == Op_CastII ) { 187 tty->print_cr("Phi has CastII use"); 188 } else { 189 tty->print_cr("Phi has use I cant be bothered with"); 190 } 191 */ 192 } 193 return NULL; 194 195 /* CNC - Cut out all the fancy acceptance tests 196 // Can we clone this use when doing the transformation? 197 // If all uses are from Phis at this merge or constants, then YES. 198 if( !v->in(0) && v != cmp ) { 199 tty->print_cr("Phi has free-floating use"); 200 v->dump(2); 201 return NULL; 202 } 203 for( uint l = 1; l < v->req(); l++ ) { 204 if( (!v->in(l)->is_Phi() || v->in(l)->in(0) != r) && 205 !v->in(l)->is_Con() ) { 206 tty->print_cr("Phi has use"); 207 v->dump(2); 208 return NULL; 209 } // End of if Phi-use input is neither Phi nor Constant 210 } // End of for all inputs to Phi-use 211 */ 212 } // End of for all uses of Phi 213 } // End of for all uses of Region 214 215 // Only do this if the IF node is in a sane state 216 if (iff->outcnt() != 2) 217 return NULL; 218 219 // Got a hit! Do the Mondo Hack! 220 // 221 //ABC a1c def ghi B 1 e h A C a c d f g i 222 // R - Phi - Phi - Phi Rc - Phi - Phi - Phi Rx - Phi - Phi - Phi 223 // cmp - 2 cmp - 2 cmp - 2 224 // bool bool_c bool_x 225 // if if_c if_x 226 // T F T F T F 227 // ..s.. ..t .. ..s.. ..t.. ..s.. ..t.. 228 // 229 // Split the paths coming into the merge point into 2 separate groups of 230 // merges. On the left will be all the paths feeding constants into the 231 // Cmp's Phi. On the right will be the remaining paths. The Cmp's Phi 232 // will fold up into a constant; this will let the Cmp fold up as well as 233 // all the control flow. Below the original IF we have 2 control 234 // dependent regions, 's' and 't'. Now we will merge the two paths 235 // just prior to 's' and 't' from the two IFs. At least 1 path (and quite 236 // likely 2 or more) will promptly constant fold away. 237 PhaseGVN *phase = igvn; 238 239 // Make a region merging constants and a region merging the rest 240 uint req_c = 0; 241 Node* predicate_proj = NULL; 242 int nb_predicate_proj = 0; 243 for (uint ii = 1; ii < r->req(); ii++) { 244 if (phi->in(ii) == con1) { 245 req_c++; 246 } 247 Node* proj = PhaseIdealLoop::find_predicate(r->in(ii)); 248 if (proj != NULL) { 249 nb_predicate_proj++; 250 predicate_proj = proj; 251 } 252 } 253 254 // If all the defs of the phi are the same constant, we already have the desired end state. 255 // Skip the split that would create empty phi and region nodes. 256 if((r->req() - req_c) == 1) { 257 return NULL; 258 } 259 260 if (nb_predicate_proj > 1) { 261 // Can happen in case of loop unswitching and when the loop is 262 // optimized out: it's not a loop anymore so we don't care about 263 // predicates. 264 assert(!r->is_Loop(), "this must not be a loop anymore"); 265 predicate_proj = NULL; 266 } 267 Node* predicate_c = NULL; 268 Node* predicate_x = NULL; 269 bool counted_loop = r->is_CountedLoop(); 270 if (counted_loop) { 271 // Ignore counted loops for now because the split-if logic does not work 272 // in all the cases (for example, with strip mined loops). Also, above 273 // checks only pass for already degraded loops without a tripcount phi 274 // and these are essentially dead and will go away during igvn. 275 return NULL; 276 } 277 278 Node *region_c = new RegionNode(req_c + 1); 279 Node *phi_c = con1; 280 uint len = r->req(); 281 Node *region_x = new RegionNode(len - req_c); 282 Node *phi_x = PhiNode::make_blank(region_x, phi); 283 for (uint i = 1, i_c = 1, i_x = 1; i < len; i++) { 284 if (phi->in(i) == con1) { 285 region_c->init_req( i_c++, r ->in(i) ); 286 if (r->in(i) == predicate_proj) 287 predicate_c = predicate_proj; 288 } else { 289 region_x->init_req( i_x, r ->in(i) ); 290 phi_x ->init_req( i_x++, phi->in(i) ); 291 if (r->in(i) == predicate_proj) 292 predicate_x = predicate_proj; 293 } 294 } 295 if (predicate_c != NULL && (req_c > 1)) { 296 assert(predicate_x == NULL, "only one predicate entry expected"); 297 predicate_c = NULL; // Do not clone predicate below merge point 298 } 299 if (predicate_x != NULL && ((len - req_c) > 2)) { 300 assert(predicate_c == NULL, "only one predicate entry expected"); 301 predicate_x = NULL; // Do not clone predicate below merge point 302 } 303 304 // Register the new RegionNodes but do not transform them. Cannot 305 // transform until the entire Region/Phi conglomerate has been hacked 306 // as a single huge transform. 307 igvn->register_new_node_with_optimizer( region_c ); 308 igvn->register_new_node_with_optimizer( region_x ); 309 // Prevent the untimely death of phi_x. Currently he has no uses. He is 310 // about to get one. If this only use goes away, then phi_x will look dead. 311 // However, he will be picking up some more uses down below. 312 Node *hook = new Node(4); 313 hook->init_req(0, phi_x); 314 hook->init_req(1, phi_c); 315 phi_x = phase->transform( phi_x ); 316 317 // Make the compare 318 Node *cmp_c = phase->makecon(t); 319 Node *cmp_x = cmp->clone(); 320 cmp_x->set_req(1,phi_x); 321 cmp_x->set_req(2,con2); 322 cmp_x = phase->transform(cmp_x); 323 // Make the bool 324 Node *b_c = phase->transform(new BoolNode(cmp_c,b->_test._test)); 325 Node *b_x = phase->transform(new BoolNode(cmp_x,b->_test._test)); 326 // Make the IfNode 327 IfNode* iff_c = iff->clone()->as_If(); 328 iff_c->set_req(0, region_c); 329 iff_c->set_req(1, b_c); 330 igvn->set_type_bottom(iff_c); 331 igvn->_worklist.push(iff_c); 332 hook->init_req(2, iff_c); 333 334 IfNode* iff_x = iff->clone()->as_If(); 335 iff_x->set_req(0, region_x); 336 iff_x->set_req(1, b_x); 337 igvn->set_type_bottom(iff_x); 338 igvn->_worklist.push(iff_x); 339 hook->init_req(3, iff_x); 340 341 // Make the true/false arms 342 Node *iff_c_t = phase->transform(new IfTrueNode (iff_c)); 343 Node *iff_c_f = phase->transform(new IfFalseNode(iff_c)); 344 if (predicate_c != NULL) { 345 assert(predicate_x == NULL, "only one predicate entry expected"); 346 // Clone loop predicates to each path 347 iff_c_t = igvn->clone_loop_predicates(predicate_c, iff_c_t, !counted_loop); 348 iff_c_f = igvn->clone_loop_predicates(predicate_c, iff_c_f, !counted_loop); 349 } 350 Node *iff_x_t = phase->transform(new IfTrueNode (iff_x)); 351 Node *iff_x_f = phase->transform(new IfFalseNode(iff_x)); 352 if (predicate_x != NULL) { 353 assert(predicate_c == NULL, "only one predicate entry expected"); 354 // Clone loop predicates to each path 355 iff_x_t = igvn->clone_loop_predicates(predicate_x, iff_x_t, !counted_loop); 356 iff_x_f = igvn->clone_loop_predicates(predicate_x, iff_x_f, !counted_loop); 357 } 358 359 // Merge the TRUE paths 360 Node *region_s = new RegionNode(3); 361 igvn->_worklist.push(region_s); 362 region_s->init_req(1, iff_c_t); 363 region_s->init_req(2, iff_x_t); 364 igvn->register_new_node_with_optimizer( region_s ); 365 366 // Merge the FALSE paths 367 Node *region_f = new RegionNode(3); 368 igvn->_worklist.push(region_f); 369 region_f->init_req(1, iff_c_f); 370 region_f->init_req(2, iff_x_f); 371 igvn->register_new_node_with_optimizer( region_f ); 372 373 igvn->hash_delete(cmp);// Remove soon-to-be-dead node from hash table. 374 cmp->set_req(1,NULL); // Whack the inputs to cmp because it will be dead 375 cmp->set_req(2,NULL); 376 // Check for all uses of the Phi and give them a new home. 377 // The 'cmp' got cloned, but CastPP/IIs need to be moved. 378 Node *phi_s = NULL; // do not construct unless needed 379 Node *phi_f = NULL; // do not construct unless needed 380 for (DUIterator_Last i2min, i2 = phi->last_outs(i2min); i2 >= i2min; --i2) { 381 Node* v = phi->last_out(i2);// User of the phi 382 igvn->rehash_node_delayed(v); // Have to fixup other Phi users 383 uint vop = v->Opcode(); 384 Node *proj = NULL; 385 if( vop == Op_Phi ) { // Remote merge point 386 Node *r = v->in(0); 387 for (uint i3 = 1; i3 < r->req(); i3++) 388 if (r->in(i3) && r->in(i3)->in(0) == iff) { 389 proj = r->in(i3); 390 break; 391 } 392 } else if( v->is_ConstraintCast() ) { 393 proj = v->in(0); // Controlling projection 394 } else { 395 assert( 0, "do not know how to handle this guy" ); 396 } 397 guarantee(proj != NULL, "sanity"); 398 399 Node *proj_path_data, *proj_path_ctrl; 400 if( proj->Opcode() == Op_IfTrue ) { 401 if( phi_s == NULL ) { 402 // Only construct phi_s if needed, otherwise provides 403 // interfering use. 404 phi_s = PhiNode::make_blank(region_s,phi); 405 phi_s->init_req( 1, phi_c ); 406 phi_s->init_req( 2, phi_x ); 407 hook->add_req(phi_s); 408 phi_s = phase->transform(phi_s); 409 } 410 proj_path_data = phi_s; 411 proj_path_ctrl = region_s; 412 } else { 413 if( phi_f == NULL ) { 414 // Only construct phi_f if needed, otherwise provides 415 // interfering use. 416 phi_f = PhiNode::make_blank(region_f,phi); 417 phi_f->init_req( 1, phi_c ); 418 phi_f->init_req( 2, phi_x ); 419 hook->add_req(phi_f); 420 phi_f = phase->transform(phi_f); 421 } 422 proj_path_data = phi_f; 423 proj_path_ctrl = region_f; 424 } 425 426 // Fixup 'v' for for the split 427 if( vop == Op_Phi ) { // Remote merge point 428 uint i; 429 for( i = 1; i < v->req(); i++ ) 430 if( v->in(i) == phi ) 431 break; 432 v->set_req(i, proj_path_data ); 433 } else if( v->is_ConstraintCast() ) { 434 v->set_req(0, proj_path_ctrl ); 435 v->set_req(1, proj_path_data ); 436 } else 437 ShouldNotReachHere(); 438 } 439 440 // Now replace the original iff's True/False with region_s/region_t. 441 // This makes the original iff go dead. 442 for (DUIterator_Last i3min, i3 = iff->last_outs(i3min); i3 >= i3min; --i3) { 443 Node* p = iff->last_out(i3); 444 assert( p->Opcode() == Op_IfTrue || p->Opcode() == Op_IfFalse, "" ); 445 Node *u = (p->Opcode() == Op_IfTrue) ? region_s : region_f; 446 // Replace p with u 447 igvn->add_users_to_worklist(p); 448 for (DUIterator_Last lmin, l = p->last_outs(lmin); l >= lmin;) { 449 Node* x = p->last_out(l); 450 igvn->hash_delete(x); 451 uint uses_found = 0; 452 for( uint j = 0; j < x->req(); j++ ) { 453 if( x->in(j) == p ) { 454 x->set_req(j, u); 455 uses_found++; 456 } 457 } 458 l -= uses_found; // we deleted 1 or more copies of this edge 459 } 460 igvn->remove_dead_node(p); 461 } 462 463 // Force the original merge dead 464 igvn->hash_delete(r); 465 // First, remove region's dead users. 466 for (DUIterator_Last lmin, l = r->last_outs(lmin); l >= lmin;) { 467 Node* u = r->last_out(l); 468 if( u == r ) { 469 r->set_req(0, NULL); 470 } else { 471 assert(u->outcnt() == 0, "only dead users"); 472 igvn->remove_dead_node(u); 473 } 474 l -= 1; 475 } 476 igvn->remove_dead_node(r); 477 478 // Now remove the bogus extra edges used to keep things alive 479 igvn->remove_dead_node( hook ); 480 481 // Must return either the original node (now dead) or a new node 482 // (Do not return a top here, since that would break the uniqueness of top.) 483 return new ConINode(TypeInt::ZERO); 484 } 485 486 // if this IfNode follows a range check pattern return the projection 487 // for the failed path 488 ProjNode* IfNode::range_check_trap_proj(int& flip_test, Node*& l, Node*& r) { 489 if (outcnt() != 2) { 490 return NULL; 491 } 492 Node* b = in(1); 493 if (b == NULL || !b->is_Bool()) return NULL; 494 BoolNode* bn = b->as_Bool(); 495 Node* cmp = bn->in(1); 496 if (cmp == NULL) return NULL; 497 if (cmp->Opcode() != Op_CmpU) return NULL; 498 499 l = cmp->in(1); 500 r = cmp->in(2); 501 flip_test = 1; 502 if (bn->_test._test == BoolTest::le) { 503 l = cmp->in(2); 504 r = cmp->in(1); 505 flip_test = 2; 506 } else if (bn->_test._test != BoolTest::lt) { 507 return NULL; 508 } 509 if (l->is_top()) return NULL; // Top input means dead test 510 if (r->Opcode() != Op_LoadRange && !is_RangeCheck()) return NULL; 511 512 // We have recognized one of these forms: 513 // Flip 1: If (Bool[<] CmpU(l, LoadRange)) ... 514 // Flip 2: If (Bool[<=] CmpU(LoadRange, l)) ... 515 516 ProjNode* iftrap = proj_out_or_null(flip_test == 2 ? true : false); 517 return iftrap; 518 } 519 520 521 //------------------------------is_range_check--------------------------------- 522 // Return 0 if not a range check. Return 1 if a range check and set index and 523 // offset. Return 2 if we had to negate the test. Index is NULL if the check 524 // is versus a constant. 525 int RangeCheckNode::is_range_check(Node* &range, Node* &index, jint &offset) { 526 int flip_test = 0; 527 Node* l = NULL; 528 Node* r = NULL; 529 ProjNode* iftrap = range_check_trap_proj(flip_test, l, r); 530 531 if (iftrap == NULL) { 532 return 0; 533 } 534 535 // Make sure it's a real range check by requiring an uncommon trap 536 // along the OOB path. Otherwise, it's possible that the user wrote 537 // something which optimized to look like a range check but behaves 538 // in some other way. 539 if (iftrap->is_uncommon_trap_proj(Deoptimization::Reason_range_check) == NULL) { 540 return 0; 541 } 542 543 // Look for index+offset form 544 Node* ind = l; 545 jint off = 0; 546 if (l->is_top()) { 547 return 0; 548 } else if (l->Opcode() == Op_AddI) { 549 if ((off = l->in(1)->find_int_con(0)) != 0) { 550 ind = l->in(2)->uncast(); 551 } else if ((off = l->in(2)->find_int_con(0)) != 0) { 552 ind = l->in(1)->uncast(); 553 } 554 } else if ((off = l->find_int_con(-1)) >= 0) { 555 // constant offset with no variable index 556 ind = NULL; 557 } else { 558 // variable index with no constant offset (or dead negative index) 559 off = 0; 560 } 561 562 // Return all the values: 563 index = ind; 564 offset = off; 565 range = r; 566 return flip_test; 567 } 568 569 //------------------------------adjust_check----------------------------------- 570 // Adjust (widen) a prior range check 571 static void adjust_check(Node* proj, Node* range, Node* index, 572 int flip, jint off_lo, PhaseIterGVN* igvn) { 573 PhaseGVN *gvn = igvn; 574 // Break apart the old check 575 Node *iff = proj->in(0); 576 Node *bol = iff->in(1); 577 if( bol->is_top() ) return; // In case a partially dead range check appears 578 // bail (or bomb[ASSERT/DEBUG]) if NOT projection-->IfNode-->BoolNode 579 DEBUG_ONLY( if( !bol->is_Bool() ) { proj->dump(3); fatal("Expect projection-->IfNode-->BoolNode"); } ) 580 if( !bol->is_Bool() ) return; 581 582 Node *cmp = bol->in(1); 583 // Compute a new check 584 Node *new_add = gvn->intcon(off_lo); 585 if( index ) { 586 new_add = off_lo ? gvn->transform(new AddINode( index, new_add )) : index; 587 } 588 Node *new_cmp = (flip == 1) 589 ? new CmpUNode( new_add, range ) 590 : new CmpUNode( range, new_add ); 591 new_cmp = gvn->transform(new_cmp); 592 // See if no need to adjust the existing check 593 if( new_cmp == cmp ) return; 594 // Else, adjust existing check 595 Node *new_bol = gvn->transform( new BoolNode( new_cmp, bol->as_Bool()->_test._test ) ); 596 igvn->rehash_node_delayed( iff ); 597 iff->set_req_X( 1, new_bol, igvn ); 598 } 599 600 //------------------------------up_one_dom------------------------------------- 601 // Walk up the dominator tree one step. Return NULL at root or true 602 // complex merges. Skips through small diamonds. 603 Node* IfNode::up_one_dom(Node *curr, bool linear_only) { 604 Node *dom = curr->in(0); 605 if( !dom ) // Found a Region degraded to a copy? 606 return curr->nonnull_req(); // Skip thru it 607 608 if( curr != dom ) // Normal walk up one step? 609 return dom; 610 611 // Use linear_only if we are still parsing, since we cannot 612 // trust the regions to be fully filled in. 613 if (linear_only) 614 return NULL; 615 616 if( dom->is_Root() ) 617 return NULL; 618 619 // Else hit a Region. Check for a loop header 620 if( dom->is_Loop() ) 621 return dom->in(1); // Skip up thru loops 622 623 // Check for small diamonds 624 Node *din1, *din2, *din3, *din4; 625 if( dom->req() == 3 && // 2-path merge point 626 (din1 = dom ->in(1)) && // Left path exists 627 (din2 = dom ->in(2)) && // Right path exists 628 (din3 = din1->in(0)) && // Left path up one 629 (din4 = din2->in(0)) ) { // Right path up one 630 if( din3->is_Call() && // Handle a slow-path call on either arm 631 (din3 = din3->in(0)) ) 632 din3 = din3->in(0); 633 if( din4->is_Call() && // Handle a slow-path call on either arm 634 (din4 = din4->in(0)) ) 635 din4 = din4->in(0); 636 if (din3 != NULL && din3 == din4 && din3->is_If()) // Regions not degraded to a copy 637 return din3; // Skip around diamonds 638 } 639 640 // Give up the search at true merges 641 return NULL; // Dead loop? Or hit root? 642 } 643 644 645 //------------------------------filtered_int_type-------------------------------- 646 // Return a possibly more restrictive type for val based on condition control flow for an if 647 const TypeInt* IfNode::filtered_int_type(PhaseGVN* gvn, Node *val, Node* if_proj) { 648 assert(if_proj && 649 (if_proj->Opcode() == Op_IfTrue || if_proj->Opcode() == Op_IfFalse), "expecting an if projection"); 650 if (if_proj->in(0) && if_proj->in(0)->is_If()) { 651 IfNode* iff = if_proj->in(0)->as_If(); 652 if (iff->in(1) && iff->in(1)->is_Bool()) { 653 BoolNode* bol = iff->in(1)->as_Bool(); 654 if (bol->in(1) && bol->in(1)->is_Cmp()) { 655 const CmpNode* cmp = bol->in(1)->as_Cmp(); 656 if (cmp->in(1) == val) { 657 const TypeInt* cmp2_t = gvn->type(cmp->in(2))->isa_int(); 658 if (cmp2_t != NULL) { 659 jint lo = cmp2_t->_lo; 660 jint hi = cmp2_t->_hi; 661 BoolTest::mask msk = if_proj->Opcode() == Op_IfTrue ? bol->_test._test : bol->_test.negate(); 662 switch (msk) { 663 case BoolTest::ne: 664 // Can't refine type 665 return NULL; 666 case BoolTest::eq: 667 return cmp2_t; 668 case BoolTest::lt: 669 lo = TypeInt::INT->_lo; 670 if (hi - 1 < hi) { 671 hi = hi - 1; 672 } 673 break; 674 case BoolTest::le: 675 lo = TypeInt::INT->_lo; 676 break; 677 case BoolTest::gt: 678 if (lo + 1 > lo) { 679 lo = lo + 1; 680 } 681 hi = TypeInt::INT->_hi; 682 break; 683 case BoolTest::ge: 684 // lo unchanged 685 hi = TypeInt::INT->_hi; 686 break; 687 default: 688 break; 689 } 690 const TypeInt* rtn_t = TypeInt::make(lo, hi, cmp2_t->_widen); 691 return rtn_t; 692 } 693 } 694 } 695 } 696 } 697 return NULL; 698 } 699 700 //------------------------------fold_compares---------------------------- 701 // See if a pair of CmpIs can be converted into a CmpU. In some cases 702 // the direction of this if is determined by the preceding if so it 703 // can be eliminate entirely. 704 // 705 // Given an if testing (CmpI n v) check for an immediately control 706 // dependent if that is testing (CmpI n v2) and has one projection 707 // leading to this if and the other projection leading to a region 708 // that merges one of this ifs control projections. 709 // 710 // If 711 // / | 712 // / | 713 // / | 714 // If | 715 // /\ | 716 // / \ | 717 // / \ | 718 // / Region 719 // 720 // Or given an if testing (CmpI n v) check for a dominating if that is 721 // testing (CmpI n v2), both having one projection leading to an 722 // uncommon trap. Allow Another independent guard in between to cover 723 // an explicit range check: 724 // if (index < 0 || index >= array.length) { 725 // which may need a null check to guard the LoadRange 726 // 727 // If 728 // / \ 729 // / \ 730 // / \ 731 // If unc 732 // /\ 733 // / \ 734 // / \ 735 // / unc 736 // 737 738 // Is the comparison for this If suitable for folding? 739 bool IfNode::cmpi_folds(PhaseIterGVN* igvn) { 740 return in(1) != NULL && 741 in(1)->is_Bool() && 742 in(1)->in(1) != NULL && 743 in(1)->in(1)->Opcode() == Op_CmpI && 744 in(1)->in(1)->in(2) != NULL && 745 in(1)->in(1)->in(2) != igvn->C->top() && 746 (in(1)->as_Bool()->_test.is_less() || 747 in(1)->as_Bool()->_test.is_greater()); 748 } 749 750 // Is a dominating control suitable for folding with this if? 751 bool IfNode::is_ctrl_folds(Node* ctrl, PhaseIterGVN* igvn) { 752 return ctrl != NULL && 753 ctrl->is_Proj() && 754 ctrl->in(0) != NULL && 755 ctrl->in(0)->Opcode() == Op_If && 756 ctrl->in(0)->outcnt() == 2 && 757 ctrl->in(0)->as_If()->cmpi_folds(igvn) && 758 // Must compare same value 759 ctrl->in(0)->in(1)->in(1)->in(1) != NULL && 760 ctrl->in(0)->in(1)->in(1)->in(1) == in(1)->in(1)->in(1); 761 } 762 763 // Do this If and the dominating If share a region? 764 bool IfNode::has_shared_region(ProjNode* proj, ProjNode*& success, ProjNode*& fail) { 765 ProjNode* otherproj = proj->other_if_proj(); 766 Node* otherproj_ctrl_use = otherproj->unique_ctrl_out(); 767 RegionNode* region = (otherproj_ctrl_use != NULL && otherproj_ctrl_use->is_Region()) ? otherproj_ctrl_use->as_Region() : NULL; 768 success = NULL; 769 fail = NULL; 770 771 if (otherproj->outcnt() == 1 && region != NULL && !region->has_phi()) { 772 for (int i = 0; i < 2; i++) { 773 ProjNode* proj = proj_out(i); 774 if (success == NULL && proj->outcnt() == 1 && proj->unique_out() == region) { 775 success = proj; 776 } else if (fail == NULL) { 777 fail = proj; 778 } else { 779 success = fail = NULL; 780 } 781 } 782 } 783 return success != NULL && fail != NULL; 784 } 785 786 bool IfNode::is_dominator_unc(CallStaticJavaNode* dom_unc, CallStaticJavaNode* unc) { 787 // Different methods and methods containing jsrs are not supported. 788 ciMethod* method = unc->jvms()->method(); 789 ciMethod* dom_method = dom_unc->jvms()->method(); 790 if (method != dom_method || method->has_jsrs()) { 791 return false; 792 } 793 // Check that both traps are in the same activation of the method (instead 794 // of two activations being inlined through different call sites) by verifying 795 // that the call stacks are equal for both JVMStates. 796 JVMState* dom_caller = dom_unc->jvms()->caller(); 797 JVMState* caller = unc->jvms()->caller(); 798 if ((dom_caller == NULL) != (caller == NULL)) { 799 // The current method must either be inlined into both dom_caller and 800 // caller or must not be inlined at all (top method). Bail out otherwise. 801 return false; 802 } else if (dom_caller != NULL && !dom_caller->same_calls_as(caller)) { 803 return false; 804 } 805 // Check that the bci of the dominating uncommon trap dominates the bci 806 // of the dominated uncommon trap. Otherwise we may not re-execute 807 // the dominated check after deoptimization from the merged uncommon trap. 808 ciTypeFlow* flow = dom_method->get_flow_analysis(); 809 int bci = unc->jvms()->bci(); 810 int dom_bci = dom_unc->jvms()->bci(); 811 if (!flow->is_dominated_by(bci, dom_bci)) { 812 return false; 813 } 814 815 return true; 816 } 817 818 // Return projection that leads to an uncommon trap if any 819 ProjNode* IfNode::uncommon_trap_proj(CallStaticJavaNode*& call) const { 820 for (int i = 0; i < 2; i++) { 821 call = proj_out(i)->is_uncommon_trap_proj(Deoptimization::Reason_none); 822 if (call != NULL) { 823 return proj_out(i); 824 } 825 } 826 return NULL; 827 } 828 829 // Do this If and the dominating If both branch out to an uncommon trap 830 bool IfNode::has_only_uncommon_traps(ProjNode* proj, ProjNode*& success, ProjNode*& fail, PhaseIterGVN* igvn) { 831 ProjNode* otherproj = proj->other_if_proj(); 832 CallStaticJavaNode* dom_unc = otherproj->is_uncommon_trap_proj(Deoptimization::Reason_none); 833 834 if (otherproj->outcnt() == 1 && dom_unc != NULL) { 835 // We need to re-execute the folded Ifs after deoptimization from the merged traps 836 if (!dom_unc->jvms()->should_reexecute()) { 837 return false; 838 } 839 840 CallStaticJavaNode* unc = NULL; 841 ProjNode* unc_proj = uncommon_trap_proj(unc); 842 if (unc_proj != NULL && unc_proj->outcnt() == 1) { 843 if (dom_unc == unc) { 844 // Allow the uncommon trap to be shared through a region 845 RegionNode* r = unc->in(0)->as_Region(); 846 if (r->outcnt() != 2 || r->req() != 3 || r->find_edge(otherproj) == -1 || r->find_edge(unc_proj) == -1) { 847 return false; 848 } 849 assert(r->has_phi() == NULL, "simple region shouldn't have a phi"); 850 } else if (dom_unc->in(0) != otherproj || unc->in(0) != unc_proj) { 851 return false; 852 } 853 854 if (!is_dominator_unc(dom_unc, unc)) { 855 return false; 856 } 857 858 // See merge_uncommon_traps: the reason of the uncommon trap 859 // will be changed and the state of the dominating If will be 860 // used. Checked that we didn't apply this transformation in a 861 // previous compilation and it didn't cause too many traps 862 ciMethod* dom_method = dom_unc->jvms()->method(); 863 int dom_bci = dom_unc->jvms()->bci(); 864 if (!igvn->C->too_many_traps(dom_method, dom_bci, Deoptimization::Reason_unstable_fused_if) && 865 !igvn->C->too_many_traps(dom_method, dom_bci, Deoptimization::Reason_range_check)) { 866 success = unc_proj; 867 fail = unc_proj->other_if_proj(); 868 return true; 869 } 870 } 871 } 872 return false; 873 } 874 875 // Check that the 2 CmpI can be folded into as single CmpU and proceed with the folding 876 bool IfNode::fold_compares_helper(ProjNode* proj, ProjNode* success, ProjNode* fail, PhaseIterGVN* igvn) { 877 Node* this_cmp = in(1)->in(1); 878 BoolNode* this_bool = in(1)->as_Bool(); 879 IfNode* dom_iff = proj->in(0)->as_If(); 880 BoolNode* dom_bool = dom_iff->in(1)->as_Bool(); 881 Node* lo = dom_iff->in(1)->in(1)->in(2); 882 Node* hi = this_cmp->in(2); 883 Node* n = this_cmp->in(1); 884 ProjNode* otherproj = proj->other_if_proj(); 885 886 const TypeInt* lo_type = IfNode::filtered_int_type(igvn, n, otherproj); 887 const TypeInt* hi_type = IfNode::filtered_int_type(igvn, n, success); 888 889 BoolTest::mask lo_test = dom_bool->_test._test; 890 BoolTest::mask hi_test = this_bool->_test._test; 891 BoolTest::mask cond = hi_test; 892 893 // convert: 894 // 895 // dom_bool = x {<,<=,>,>=} a 896 // / \ 897 // proj = {True,False} / \ otherproj = {False,True} 898 // / 899 // this_bool = x {<,<=} b 900 // / \ 901 // fail = {True,False} / \ success = {False,True} 902 // / 903 // 904 // (Second test guaranteed canonicalized, first one may not have 905 // been canonicalized yet) 906 // 907 // into: 908 // 909 // cond = (x - lo) {<u,<=u,>u,>=u} adjusted_lim 910 // / \ 911 // fail / \ success 912 // / 913 // 914 915 // Figure out which of the two tests sets the upper bound and which 916 // sets the lower bound if any. 917 Node* adjusted_lim = NULL; 918 if (lo_type != NULL && hi_type != NULL && hi_type->_lo > lo_type->_hi && 919 hi_type->_hi == max_jint && lo_type->_lo == min_jint) { 920 assert((dom_bool->_test.is_less() && !proj->_con) || 921 (dom_bool->_test.is_greater() && proj->_con), "incorrect test"); 922 // this test was canonicalized 923 assert(this_bool->_test.is_less() && fail->_con, "incorrect test"); 924 925 // this_bool = < 926 // dom_bool = >= (proj = True) or dom_bool = < (proj = False) 927 // x in [a, b[ on the fail (= True) projection, b > a-1 (because of hi_type->_lo > lo_type->_hi test above): 928 // lo = a, hi = b, adjusted_lim = b-a, cond = <u 929 // dom_bool = > (proj = True) or dom_bool = <= (proj = False) 930 // x in ]a, b[ on the fail (= True) projection, b > a: 931 // lo = a+1, hi = b, adjusted_lim = b-a-1, cond = <u 932 // this_bool = <= 933 // dom_bool = >= (proj = True) or dom_bool = < (proj = False) 934 // x in [a, b] on the fail (= True) projection, b+1 > a-1: 935 // lo = a, hi = b, adjusted_lim = b-a+1, cond = <u 936 // lo = a, hi = b, adjusted_lim = b-a, cond = <=u doesn't work because b = a - 1 is possible, then b-a = -1 937 // dom_bool = > (proj = True) or dom_bool = <= (proj = False) 938 // x in ]a, b] on the fail (= True) projection b+1 > a: 939 // lo = a+1, hi = b, adjusted_lim = b-a, cond = <u 940 // lo = a+1, hi = b, adjusted_lim = b-a-1, cond = <=u doesn't work because a = b is possible, then b-a-1 = -1 941 942 if (hi_test == BoolTest::lt) { 943 if (lo_test == BoolTest::gt || lo_test == BoolTest::le) { 944 lo = igvn->transform(new AddINode(lo, igvn->intcon(1))); 945 } 946 } else { 947 assert(hi_test == BoolTest::le, "bad test"); 948 if (lo_test == BoolTest::ge || lo_test == BoolTest::lt) { 949 adjusted_lim = igvn->transform(new SubINode(hi, lo)); 950 adjusted_lim = igvn->transform(new AddINode(adjusted_lim, igvn->intcon(1))); 951 cond = BoolTest::lt; 952 } else { 953 assert(lo_test == BoolTest::gt || lo_test == BoolTest::le, "bad test"); 954 adjusted_lim = igvn->transform(new SubINode(hi, lo)); 955 lo = igvn->transform(new AddINode(lo, igvn->intcon(1))); 956 cond = BoolTest::lt; 957 } 958 } 959 } else if (lo_type != NULL && hi_type != NULL && lo_type->_lo > hi_type->_hi && 960 lo_type->_hi == max_jint && hi_type->_lo == min_jint) { 961 962 // this_bool = < 963 // dom_bool = < (proj = True) or dom_bool = >= (proj = False) 964 // x in [b, a[ on the fail (= False) projection, a > b-1 (because of lo_type->_lo > hi_type->_hi above): 965 // lo = b, hi = a, adjusted_lim = a-b, cond = >=u 966 // dom_bool = <= (proj = True) or dom_bool = > (proj = False) 967 // x in [b, a] on the fail (= False) projection, a+1 > b-1: 968 // lo = b, hi = a, adjusted_lim = a-b+1, cond = >=u 969 // lo = b, hi = a, adjusted_lim = a-b, cond = >u doesn't work because a = b - 1 is possible, then b-a = -1 970 // this_bool = <= 971 // dom_bool = < (proj = True) or dom_bool = >= (proj = False) 972 // x in ]b, a[ on the fail (= False) projection, a > b: 973 // lo = b+1, hi = a, adjusted_lim = a-b-1, cond = >=u 974 // dom_bool = <= (proj = True) or dom_bool = > (proj = False) 975 // x in ]b, a] on the fail (= False) projection, a+1 > b: 976 // lo = b+1, hi = a, adjusted_lim = a-b, cond = >=u 977 // lo = b+1, hi = a, adjusted_lim = a-b-1, cond = >u doesn't work because a = b is possible, then b-a-1 = -1 978 979 swap(lo, hi); 980 swap(lo_type, hi_type); 981 swap(lo_test, hi_test); 982 983 assert((dom_bool->_test.is_less() && proj->_con) || 984 (dom_bool->_test.is_greater() && !proj->_con), "incorrect test"); 985 // this test was canonicalized 986 assert(this_bool->_test.is_less() && !fail->_con, "incorrect test"); 987 988 cond = (hi_test == BoolTest::le || hi_test == BoolTest::gt) ? BoolTest::gt : BoolTest::ge; 989 990 if (lo_test == BoolTest::lt) { 991 if (hi_test == BoolTest::lt || hi_test == BoolTest::ge) { 992 cond = BoolTest::ge; 993 } else { 994 assert(hi_test == BoolTest::le || hi_test == BoolTest::gt, "bad test"); 995 adjusted_lim = igvn->transform(new SubINode(hi, lo)); 996 adjusted_lim = igvn->transform(new AddINode(adjusted_lim, igvn->intcon(1))); 997 cond = BoolTest::ge; 998 } 999 } else if (lo_test == BoolTest::le) { 1000 if (hi_test == BoolTest::lt || hi_test == BoolTest::ge) { 1001 lo = igvn->transform(new AddINode(lo, igvn->intcon(1))); 1002 cond = BoolTest::ge; 1003 } else { 1004 assert(hi_test == BoolTest::le || hi_test == BoolTest::gt, "bad test"); 1005 adjusted_lim = igvn->transform(new SubINode(hi, lo)); 1006 lo = igvn->transform(new AddINode(lo, igvn->intcon(1))); 1007 cond = BoolTest::ge; 1008 } 1009 } 1010 } else { 1011 const TypeInt* failtype = filtered_int_type(igvn, n, proj); 1012 if (failtype != NULL) { 1013 const TypeInt* type2 = filtered_int_type(igvn, n, fail); 1014 if (type2 != NULL) { 1015 failtype = failtype->join(type2)->is_int(); 1016 if (failtype->_lo > failtype->_hi) { 1017 // previous if determines the result of this if so 1018 // replace Bool with constant 1019 igvn->_worklist.push(in(1)); 1020 igvn->replace_input_of(this, 1, igvn->intcon(success->_con)); 1021 return true; 1022 } 1023 } 1024 } 1025 lo = NULL; 1026 hi = NULL; 1027 } 1028 1029 if (lo && hi) { 1030 // Merge the two compares into a single unsigned compare by building (CmpU (n - lo) (hi - lo)) 1031 Node* adjusted_val = igvn->transform(new SubINode(n, lo)); 1032 if (adjusted_lim == NULL) { 1033 adjusted_lim = igvn->transform(new SubINode(hi, lo)); 1034 } 1035 Node* newcmp = igvn->transform(new CmpUNode(adjusted_val, adjusted_lim)); 1036 Node* newbool = igvn->transform(new BoolNode(newcmp, cond)); 1037 1038 igvn->replace_input_of(dom_iff, 1, igvn->intcon(proj->_con)); 1039 igvn->_worklist.push(in(1)); 1040 igvn->replace_input_of(this, 1, newbool); 1041 1042 return true; 1043 } 1044 return false; 1045 } 1046 1047 // Merge the branches that trap for this If and the dominating If into 1048 // a single region that branches to the uncommon trap for the 1049 // dominating If 1050 Node* IfNode::merge_uncommon_traps(ProjNode* proj, ProjNode* success, ProjNode* fail, PhaseIterGVN* igvn) { 1051 Node* res = this; 1052 assert(success->in(0) == this, "bad projection"); 1053 1054 ProjNode* otherproj = proj->other_if_proj(); 1055 1056 CallStaticJavaNode* unc = success->is_uncommon_trap_proj(Deoptimization::Reason_none); 1057 CallStaticJavaNode* dom_unc = otherproj->is_uncommon_trap_proj(Deoptimization::Reason_none); 1058 1059 if (unc != dom_unc) { 1060 Node* r = new RegionNode(3); 1061 1062 r->set_req(1, otherproj); 1063 r->set_req(2, success); 1064 r = igvn->transform(r); 1065 assert(r->is_Region(), "can't go away"); 1066 1067 // Make both If trap at the state of the first If: once the CmpI 1068 // nodes are merged, if we trap we don't know which of the CmpI 1069 // nodes would have caused the trap so we have to restart 1070 // execution at the first one 1071 igvn->replace_input_of(dom_unc, 0, r); 1072 igvn->replace_input_of(unc, 0, igvn->C->top()); 1073 } 1074 int trap_request = dom_unc->uncommon_trap_request(); 1075 Deoptimization::DeoptReason reason = Deoptimization::trap_request_reason(trap_request); 1076 Deoptimization::DeoptAction action = Deoptimization::trap_request_action(trap_request); 1077 1078 int flip_test = 0; 1079 Node* l = NULL; 1080 Node* r = NULL; 1081 1082 if (success->in(0)->as_If()->range_check_trap_proj(flip_test, l, r) != NULL) { 1083 // If this looks like a range check, change the trap to 1084 // Reason_range_check so the compiler recognizes it as a range 1085 // check and applies the corresponding optimizations 1086 trap_request = Deoptimization::make_trap_request(Deoptimization::Reason_range_check, action); 1087 1088 improve_address_types(l, r, fail, igvn); 1089 1090 res = igvn->transform(new RangeCheckNode(in(0), in(1), _prob, _fcnt)); 1091 } else if (unc != dom_unc) { 1092 // If we trap we won't know what CmpI would have caused the trap 1093 // so use a special trap reason to mark this pair of CmpI nodes as 1094 // bad candidate for folding. On recompilation we won't fold them 1095 // and we may trap again but this time we'll know what branch 1096 // traps 1097 trap_request = Deoptimization::make_trap_request(Deoptimization::Reason_unstable_fused_if, action); 1098 } 1099 igvn->replace_input_of(dom_unc, TypeFunc::Parms, igvn->intcon(trap_request)); 1100 return res; 1101 } 1102 1103 // If we are turning 2 CmpI nodes into a CmpU that follows the pattern 1104 // of a rangecheck on index i, on 64 bit the compares may be followed 1105 // by memory accesses using i as index. In that case, the CmpU tells 1106 // us something about the values taken by i that can help the compiler 1107 // (see Compile::conv_I2X_index()) 1108 void IfNode::improve_address_types(Node* l, Node* r, ProjNode* fail, PhaseIterGVN* igvn) { 1109 #ifdef _LP64 1110 ResourceMark rm; 1111 Node_Stack stack(2); 1112 1113 assert(r->Opcode() == Op_LoadRange, "unexpected range check"); 1114 const TypeInt* array_size = igvn->type(r)->is_int(); 1115 1116 stack.push(l, 0); 1117 1118 while(stack.size() > 0) { 1119 Node* n = stack.node(); 1120 uint start = stack.index(); 1121 1122 uint i = start; 1123 for (; i < n->outcnt(); i++) { 1124 Node* use = n->raw_out(i); 1125 if (stack.size() == 1) { 1126 if (use->Opcode() == Op_ConvI2L) { 1127 const TypeLong* bounds = use->as_Type()->type()->is_long(); 1128 if (bounds->_lo <= array_size->_lo && bounds->_hi >= array_size->_hi && 1129 (bounds->_lo != array_size->_lo || bounds->_hi != array_size->_hi)) { 1130 stack.set_index(i+1); 1131 stack.push(use, 0); 1132 break; 1133 } 1134 } 1135 } else if (use->is_Mem()) { 1136 Node* ctrl = use->in(0); 1137 for (int i = 0; i < 10 && ctrl != NULL && ctrl != fail; i++) { 1138 ctrl = up_one_dom(ctrl); 1139 } 1140 if (ctrl == fail) { 1141 Node* init_n = stack.node_at(1); 1142 assert(init_n->Opcode() == Op_ConvI2L, "unexpected first node"); 1143 // Create a new narrow ConvI2L node that is dependent on the range check 1144 Node* new_n = igvn->C->conv_I2X_index(igvn, l, array_size, fail); 1145 1146 // The type of the ConvI2L may be widen and so the new 1147 // ConvI2L may not be better than an existing ConvI2L 1148 if (new_n != init_n) { 1149 for (uint j = 2; j < stack.size(); j++) { 1150 Node* n = stack.node_at(j); 1151 Node* clone = n->clone(); 1152 int rep = clone->replace_edge(init_n, new_n); 1153 assert(rep > 0, "can't find expected node?"); 1154 clone = igvn->transform(clone); 1155 init_n = n; 1156 new_n = clone; 1157 } 1158 igvn->hash_delete(use); 1159 int rep = use->replace_edge(init_n, new_n); 1160 assert(rep > 0, "can't find expected node?"); 1161 igvn->transform(use); 1162 if (init_n->outcnt() == 0) { 1163 igvn->_worklist.push(init_n); 1164 } 1165 } 1166 } 1167 } else if (use->in(0) == NULL && (igvn->type(use)->isa_long() || 1168 igvn->type(use)->isa_ptr())) { 1169 stack.set_index(i+1); 1170 stack.push(use, 0); 1171 break; 1172 } 1173 } 1174 if (i == n->outcnt()) { 1175 stack.pop(); 1176 } 1177 } 1178 #endif 1179 } 1180 1181 bool IfNode::is_cmp_with_loadrange(ProjNode* proj) { 1182 if (in(1) != NULL && 1183 in(1)->in(1) != NULL && 1184 in(1)->in(1)->in(2) != NULL) { 1185 Node* other = in(1)->in(1)->in(2); 1186 if (other->Opcode() == Op_LoadRange && 1187 ((other->in(0) != NULL && other->in(0) == proj) || 1188 (other->in(0) == NULL && 1189 other->in(2) != NULL && 1190 other->in(2)->is_AddP() && 1191 other->in(2)->in(1) != NULL && 1192 other->in(2)->in(1)->Opcode() == Op_CastPP && 1193 other->in(2)->in(1)->in(0) == proj))) { 1194 return true; 1195 } 1196 } 1197 return false; 1198 } 1199 1200 bool IfNode::is_null_check(ProjNode* proj, PhaseIterGVN* igvn) { 1201 Node* other = in(1)->in(1)->in(2); 1202 if (other->in(MemNode::Address) != NULL && 1203 proj->in(0)->in(1) != NULL && 1204 proj->in(0)->in(1)->is_Bool() && 1205 proj->in(0)->in(1)->in(1) != NULL && 1206 proj->in(0)->in(1)->in(1)->Opcode() == Op_CmpP && 1207 proj->in(0)->in(1)->in(1)->in(2) != NULL && 1208 proj->in(0)->in(1)->in(1)->in(1) == other->in(MemNode::Address)->in(AddPNode::Address)->uncast() && 1209 igvn->type(proj->in(0)->in(1)->in(1)->in(2)) == TypePtr::NULL_PTR) { 1210 return true; 1211 } 1212 return false; 1213 } 1214 1215 // Check that the If that is in between the 2 integer comparisons has 1216 // no side effect 1217 bool IfNode::is_side_effect_free_test(ProjNode* proj, PhaseIterGVN* igvn) { 1218 if (proj == NULL) { 1219 return false; 1220 } 1221 CallStaticJavaNode* unc = proj->is_uncommon_trap_if_pattern(Deoptimization::Reason_none); 1222 if (unc != NULL && proj->outcnt() <= 2) { 1223 if (proj->outcnt() == 1 || 1224 // Allow simple null check from LoadRange 1225 (is_cmp_with_loadrange(proj) && is_null_check(proj, igvn))) { 1226 CallStaticJavaNode* unc = proj->is_uncommon_trap_if_pattern(Deoptimization::Reason_none); 1227 CallStaticJavaNode* dom_unc = proj->in(0)->in(0)->as_Proj()->is_uncommon_trap_if_pattern(Deoptimization::Reason_none); 1228 assert(dom_unc != NULL, "is_uncommon_trap_if_pattern returned NULL"); 1229 1230 // reroute_side_effect_free_unc changes the state of this 1231 // uncommon trap to restart execution at the previous 1232 // CmpI. Check that this change in a previous compilation didn't 1233 // cause too many traps. 1234 int trap_request = unc->uncommon_trap_request(); 1235 Deoptimization::DeoptReason reason = Deoptimization::trap_request_reason(trap_request); 1236 1237 if (igvn->C->too_many_traps(dom_unc->jvms()->method(), dom_unc->jvms()->bci(), reason)) { 1238 return false; 1239 } 1240 1241 if (!is_dominator_unc(dom_unc, unc)) { 1242 return false; 1243 } 1244 1245 return true; 1246 } 1247 } 1248 return false; 1249 } 1250 1251 // Make the If between the 2 integer comparisons trap at the state of 1252 // the first If: the last CmpI is the one replaced by a CmpU and the 1253 // first CmpI is eliminated, so the test between the 2 CmpI nodes 1254 // won't be guarded by the first CmpI anymore. It can trap in cases 1255 // where the first CmpI would have prevented it from executing: on a 1256 // trap, we need to restart execution at the state of the first CmpI 1257 void IfNode::reroute_side_effect_free_unc(ProjNode* proj, ProjNode* dom_proj, PhaseIterGVN* igvn) { 1258 CallStaticJavaNode* dom_unc = dom_proj->is_uncommon_trap_if_pattern(Deoptimization::Reason_none); 1259 ProjNode* otherproj = proj->other_if_proj(); 1260 CallStaticJavaNode* unc = proj->is_uncommon_trap_if_pattern(Deoptimization::Reason_none); 1261 Node* call_proj = dom_unc->unique_ctrl_out(); 1262 Node* halt = call_proj->unique_ctrl_out(); 1263 1264 Node* new_unc = dom_unc->clone(); 1265 call_proj = call_proj->clone(); 1266 halt = halt->clone(); 1267 Node* c = otherproj->clone(); 1268 1269 c = igvn->transform(c); 1270 new_unc->set_req(TypeFunc::Parms, unc->in(TypeFunc::Parms)); 1271 new_unc->set_req(0, c); 1272 new_unc = igvn->transform(new_unc); 1273 call_proj->set_req(0, new_unc); 1274 call_proj = igvn->transform(call_proj); 1275 halt->set_req(0, call_proj); 1276 halt = igvn->transform(halt); 1277 1278 igvn->replace_node(otherproj, igvn->C->top()); 1279 igvn->C->root()->add_req(halt); 1280 } 1281 1282 Node* IfNode::fold_compares(PhaseIterGVN* igvn) { 1283 if (Opcode() != Op_If) return NULL; 1284 1285 if (cmpi_folds(igvn)) { 1286 Node* ctrl = in(0); 1287 if (is_ctrl_folds(ctrl, igvn) && 1288 ctrl->outcnt() == 1) { 1289 // A integer comparison immediately dominated by another integer 1290 // comparison 1291 ProjNode* success = NULL; 1292 ProjNode* fail = NULL; 1293 ProjNode* dom_cmp = ctrl->as_Proj(); 1294 if (has_shared_region(dom_cmp, success, fail) && 1295 // Next call modifies graph so must be last 1296 fold_compares_helper(dom_cmp, success, fail, igvn)) { 1297 return this; 1298 } 1299 if (has_only_uncommon_traps(dom_cmp, success, fail, igvn) && 1300 // Next call modifies graph so must be last 1301 fold_compares_helper(dom_cmp, success, fail, igvn)) { 1302 return merge_uncommon_traps(dom_cmp, success, fail, igvn); 1303 } 1304 return NULL; 1305 } else if (ctrl->in(0) != NULL && 1306 ctrl->in(0)->in(0) != NULL) { 1307 ProjNode* success = NULL; 1308 ProjNode* fail = NULL; 1309 Node* dom = ctrl->in(0)->in(0); 1310 ProjNode* dom_cmp = dom->isa_Proj(); 1311 ProjNode* other_cmp = ctrl->isa_Proj(); 1312 1313 // Check if it's an integer comparison dominated by another 1314 // integer comparison with another test in between 1315 if (is_ctrl_folds(dom, igvn) && 1316 has_only_uncommon_traps(dom_cmp, success, fail, igvn) && 1317 is_side_effect_free_test(other_cmp, igvn) && 1318 // Next call modifies graph so must be last 1319 fold_compares_helper(dom_cmp, success, fail, igvn)) { 1320 reroute_side_effect_free_unc(other_cmp, dom_cmp, igvn); 1321 return merge_uncommon_traps(dom_cmp, success, fail, igvn); 1322 } 1323 } 1324 } 1325 return NULL; 1326 } 1327 1328 //------------------------------remove_useless_bool---------------------------- 1329 // Check for people making a useless boolean: things like 1330 // if( (x < y ? true : false) ) { ... } 1331 // Replace with if( x < y ) { ... } 1332 static Node *remove_useless_bool(IfNode *iff, PhaseGVN *phase) { 1333 Node *i1 = iff->in(1); 1334 if( !i1->is_Bool() ) return NULL; 1335 BoolNode *bol = i1->as_Bool(); 1336 1337 Node *cmp = bol->in(1); 1338 if( cmp->Opcode() != Op_CmpI ) return NULL; 1339 1340 // Must be comparing against a bool 1341 const Type *cmp2_t = phase->type( cmp->in(2) ); 1342 if( cmp2_t != TypeInt::ZERO && 1343 cmp2_t != TypeInt::ONE ) 1344 return NULL; 1345 1346 // Find a prior merge point merging the boolean 1347 i1 = cmp->in(1); 1348 if( !i1->is_Phi() ) return NULL; 1349 PhiNode *phi = i1->as_Phi(); 1350 if( phase->type( phi ) != TypeInt::BOOL ) 1351 return NULL; 1352 1353 // Check for diamond pattern 1354 int true_path = phi->is_diamond_phi(); 1355 if( true_path == 0 ) return NULL; 1356 1357 // Make sure that iff and the control of the phi are different. This 1358 // should really only happen for dead control flow since it requires 1359 // an illegal cycle. 1360 if (phi->in(0)->in(1)->in(0) == iff) return NULL; 1361 1362 // phi->region->if_proj->ifnode->bool->cmp 1363 BoolNode *bol2 = phi->in(0)->in(1)->in(0)->in(1)->as_Bool(); 1364 1365 // Now get the 'sense' of the test correct so we can plug in 1366 // either iff2->in(1) or its complement. 1367 int flip = 0; 1368 if( bol->_test._test == BoolTest::ne ) flip = 1-flip; 1369 else if( bol->_test._test != BoolTest::eq ) return NULL; 1370 if( cmp2_t == TypeInt::ZERO ) flip = 1-flip; 1371 1372 const Type *phi1_t = phase->type( phi->in(1) ); 1373 const Type *phi2_t = phase->type( phi->in(2) ); 1374 // Check for Phi(0,1) and flip 1375 if( phi1_t == TypeInt::ZERO ) { 1376 if( phi2_t != TypeInt::ONE ) return NULL; 1377 flip = 1-flip; 1378 } else { 1379 // Check for Phi(1,0) 1380 if( phi1_t != TypeInt::ONE ) return NULL; 1381 if( phi2_t != TypeInt::ZERO ) return NULL; 1382 } 1383 if( true_path == 2 ) { 1384 flip = 1-flip; 1385 } 1386 1387 Node* new_bol = (flip ? phase->transform( bol2->negate(phase) ) : bol2); 1388 assert(new_bol != iff->in(1), "must make progress"); 1389 iff->set_req(1, new_bol); 1390 // Intervening diamond probably goes dead 1391 phase->C->set_major_progress(); 1392 return iff; 1393 } 1394 1395 static IfNode* idealize_test(PhaseGVN* phase, IfNode* iff); 1396 1397 struct RangeCheck { 1398 Node* ctl; 1399 jint off; 1400 }; 1401 1402 Node* IfNode::Ideal_common(PhaseGVN *phase, bool can_reshape) { 1403 if (remove_dead_region(phase, can_reshape)) return this; 1404 // No Def-Use info? 1405 if (!can_reshape) return NULL; 1406 1407 // Don't bother trying to transform a dead if 1408 if (in(0)->is_top()) return NULL; 1409 // Don't bother trying to transform an if with a dead test 1410 if (in(1)->is_top()) return NULL; 1411 // Another variation of a dead test 1412 if (in(1)->is_Con()) return NULL; 1413 // Another variation of a dead if 1414 if (outcnt() < 2) return NULL; 1415 1416 // Canonicalize the test. 1417 Node* idt_if = idealize_test(phase, this); 1418 if (idt_if != NULL) return idt_if; 1419 1420 // Try to split the IF 1421 PhaseIterGVN *igvn = phase->is_IterGVN(); 1422 Node *s = split_if(this, igvn); 1423 if (s != NULL) return s; 1424 1425 return NodeSentinel; 1426 } 1427 1428 //------------------------------Ideal------------------------------------------ 1429 // Return a node which is more "ideal" than the current node. Strip out 1430 // control copies 1431 Node* IfNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1432 Node* res = Ideal_common(phase, can_reshape); 1433 if (res != NodeSentinel) { 1434 return res; 1435 } 1436 1437 // Check for people making a useless boolean: things like 1438 // if( (x < y ? true : false) ) { ... } 1439 // Replace with if( x < y ) { ... } 1440 Node *bol2 = remove_useless_bool(this, phase); 1441 if( bol2 ) return bol2; 1442 1443 if (in(0) == NULL) return NULL; // Dead loop? 1444 1445 PhaseIterGVN *igvn = phase->is_IterGVN(); 1446 Node* result = fold_compares(igvn); 1447 if (result != NULL) { 1448 return result; 1449 } 1450 1451 // Scan for an equivalent test 1452 Node *cmp; 1453 int dist = 0; // Cutoff limit for search 1454 int op = Opcode(); 1455 if( op == Op_If && 1456 (cmp=in(1)->in(1))->Opcode() == Op_CmpP ) { 1457 if( cmp->in(2) != NULL && // make sure cmp is not already dead 1458 cmp->in(2)->bottom_type() == TypePtr::NULL_PTR ) { 1459 dist = 64; // Limit for null-pointer scans 1460 } else { 1461 dist = 4; // Do not bother for random pointer tests 1462 } 1463 } else { 1464 dist = 4; // Limit for random junky scans 1465 } 1466 1467 Node* prev_dom = search_identical(dist); 1468 1469 if (prev_dom == NULL) { 1470 return NULL; 1471 } 1472 1473 // Replace dominated IfNode 1474 return dominated_by(prev_dom, igvn); 1475 } 1476 1477 //------------------------------dominated_by----------------------------------- 1478 Node* IfNode::dominated_by(Node* prev_dom, PhaseIterGVN *igvn) { 1479 #ifndef PRODUCT 1480 if (TraceIterativeGVN) { 1481 tty->print(" Removing IfNode: "); this->dump(); 1482 } 1483 if (VerifyOpto && !igvn->allow_progress()) { 1484 // Found an equivalent dominating test, 1485 // we can not guarantee reaching a fix-point for these during iterativeGVN 1486 // since intervening nodes may not change. 1487 return NULL; 1488 } 1489 #endif 1490 1491 igvn->hash_delete(this); // Remove self to prevent spurious V-N 1492 Node *idom = in(0); 1493 // Need opcode to decide which way 'this' test goes 1494 int prev_op = prev_dom->Opcode(); 1495 Node *top = igvn->C->top(); // Shortcut to top 1496 1497 // Loop predicates may have depending checks which should not 1498 // be skipped. For example, range check predicate has two checks 1499 // for lower and upper bounds. 1500 ProjNode* unc_proj = proj_out(1 - prev_dom->as_Proj()->_con)->as_Proj(); 1501 if (unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_predicate) != NULL || 1502 unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_profile_predicate) != NULL) { 1503 prev_dom = idom; 1504 } 1505 1506 // Now walk the current IfNode's projections. 1507 // Loop ends when 'this' has no more uses. 1508 for (DUIterator_Last imin, i = last_outs(imin); i >= imin; --i) { 1509 Node *ifp = last_out(i); // Get IfTrue/IfFalse 1510 igvn->add_users_to_worklist(ifp); 1511 // Check which projection it is and set target. 1512 // Data-target is either the dominating projection of the same type 1513 // or TOP if the dominating projection is of opposite type. 1514 // Data-target will be used as the new control edge for the non-CFG 1515 // nodes like Casts and Loads. 1516 Node *data_target = (ifp->Opcode() == prev_op) ? prev_dom : top; 1517 // Control-target is just the If's immediate dominator or TOP. 1518 Node *ctrl_target = (ifp->Opcode() == prev_op) ? idom : top; 1519 1520 // For each child of an IfTrue/IfFalse projection, reroute. 1521 // Loop ends when projection has no more uses. 1522 for (DUIterator_Last jmin, j = ifp->last_outs(jmin); j >= jmin; --j) { 1523 Node* s = ifp->last_out(j); // Get child of IfTrue/IfFalse 1524 if( !s->depends_only_on_test() ) { 1525 // Find the control input matching this def-use edge. 1526 // For Regions it may not be in slot 0. 1527 uint l; 1528 for( l = 0; s->in(l) != ifp; l++ ) { } 1529 igvn->replace_input_of(s, l, ctrl_target); 1530 } else { // Else, for control producers, 1531 igvn->replace_input_of(s, 0, data_target); // Move child to data-target 1532 } 1533 } // End for each child of a projection 1534 1535 igvn->remove_dead_node(ifp); 1536 } // End for each IfTrue/IfFalse child of If 1537 1538 // Kill the IfNode 1539 igvn->remove_dead_node(this); 1540 1541 // Must return either the original node (now dead) or a new node 1542 // (Do not return a top here, since that would break the uniqueness of top.) 1543 return new ConINode(TypeInt::ZERO); 1544 } 1545 1546 Node* IfNode::search_identical(int dist) { 1547 // Setup to scan up the CFG looking for a dominating test 1548 Node* dom = in(0); 1549 Node* prev_dom = this; 1550 int op = Opcode(); 1551 // Search up the dominator tree for an If with an identical test 1552 while (dom->Opcode() != op || // Not same opcode? 1553 dom->in(1) != in(1) || // Not same input 1? 1554 prev_dom->in(0) != dom) { // One path of test does not dominate? 1555 if (dist < 0) return NULL; 1556 1557 dist--; 1558 prev_dom = dom; 1559 dom = up_one_dom(dom); 1560 if (!dom) return NULL; 1561 } 1562 1563 // Check that we did not follow a loop back to ourselves 1564 if (this == dom) { 1565 return NULL; 1566 } 1567 1568 #ifndef PRODUCT 1569 if (dist > 2) { // Add to count of NULL checks elided 1570 explicit_null_checks_elided++; 1571 } 1572 #endif 1573 1574 return prev_dom; 1575 } 1576 1577 //------------------------------Identity--------------------------------------- 1578 // If the test is constant & we match, then we are the input Control 1579 Node* IfProjNode::Identity(PhaseGVN* phase) { 1580 // Can only optimize if cannot go the other way 1581 const TypeTuple *t = phase->type(in(0))->is_tuple(); 1582 if (t == TypeTuple::IFNEITHER || (always_taken(t) && 1583 // During parsing (GVN) we don't remove dead code aggressively. 1584 // Cut off dead branch and let PhaseRemoveUseless take care of it. 1585 (!phase->is_IterGVN() || 1586 // During IGVN, first wait for the dead branch to be killed. 1587 // Otherwise, the IfNode's control will have two control uses (the IfNode 1588 // that doesn't go away because it still has uses and this branch of the 1589 // If) which breaks other optimizations. Node::has_special_unique_user() 1590 // will cause this node to be reprocessed once the dead branch is killed. 1591 in(0)->outcnt() == 1))) { 1592 // IfNode control 1593 return in(0)->in(0); 1594 } 1595 // no progress 1596 return this; 1597 } 1598 1599 #ifndef PRODUCT 1600 //-------------------------------related--------------------------------------- 1601 // An IfProjNode's related node set consists of its input (an IfNode) including 1602 // the IfNode's condition, plus all of its outputs at level 1. In compact mode, 1603 // the restrictions for IfNode apply (see IfNode::rel). 1604 void IfProjNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const { 1605 Node* ifNode = this->in(0); 1606 in_rel->append(ifNode); 1607 if (compact) { 1608 ifNode->collect_nodes(in_rel, 3, false, true); 1609 } else { 1610 ifNode->collect_nodes_in_all_data(in_rel, false); 1611 } 1612 this->collect_nodes(out_rel, -1, false, false); 1613 } 1614 1615 //------------------------------dump_spec-------------------------------------- 1616 void IfNode::dump_spec(outputStream *st) const { 1617 st->print("P=%f, C=%f",_prob,_fcnt); 1618 } 1619 1620 //-------------------------------related--------------------------------------- 1621 // For an IfNode, the set of related output nodes is just the output nodes till 1622 // depth 2, i.e, the IfTrue/IfFalse projection nodes plus the nodes they refer. 1623 // The related input nodes contain no control nodes, but all data nodes 1624 // pertaining to the condition. In compact mode, the input nodes are collected 1625 // up to a depth of 3. 1626 void IfNode::related(GrowableArray <Node *> *in_rel, GrowableArray <Node *> *out_rel, bool compact) const { 1627 if (compact) { 1628 this->collect_nodes(in_rel, 3, false, true); 1629 } else { 1630 this->collect_nodes_in_all_data(in_rel, false); 1631 } 1632 this->collect_nodes(out_rel, -2, false, false); 1633 } 1634 #endif 1635 1636 //------------------------------idealize_test---------------------------------- 1637 // Try to canonicalize tests better. Peek at the Cmp/Bool/If sequence and 1638 // come up with a canonical sequence. Bools getting 'eq', 'gt' and 'ge' forms 1639 // converted to 'ne', 'le' and 'lt' forms. IfTrue/IfFalse get swapped as 1640 // needed. 1641 static IfNode* idealize_test(PhaseGVN* phase, IfNode* iff) { 1642 assert(iff->in(0) != NULL, "If must be live"); 1643 1644 if (iff->outcnt() != 2) return NULL; // Malformed projections. 1645 Node* old_if_f = iff->proj_out(false); 1646 Node* old_if_t = iff->proj_out(true); 1647 1648 // CountedLoopEnds want the back-control test to be TRUE, irregardless of 1649 // whether they are testing a 'gt' or 'lt' condition. The 'gt' condition 1650 // happens in count-down loops 1651 if (iff->is_CountedLoopEnd()) return NULL; 1652 if (!iff->in(1)->is_Bool()) return NULL; // Happens for partially optimized IF tests 1653 BoolNode *b = iff->in(1)->as_Bool(); 1654 BoolTest bt = b->_test; 1655 // Test already in good order? 1656 if( bt.is_canonical() ) 1657 return NULL; 1658 1659 // Flip test to be canonical. Requires flipping the IfFalse/IfTrue and 1660 // cloning the IfNode. 1661 Node* new_b = phase->transform( new BoolNode(b->in(1), bt.negate()) ); 1662 if( !new_b->is_Bool() ) return NULL; 1663 b = new_b->as_Bool(); 1664 1665 PhaseIterGVN *igvn = phase->is_IterGVN(); 1666 assert( igvn, "Test is not canonical in parser?" ); 1667 1668 // The IF node never really changes, but it needs to be cloned 1669 iff = iff->clone()->as_If(); 1670 iff->set_req(1, b); 1671 iff->_prob = 1.0-iff->_prob; 1672 1673 Node *prior = igvn->hash_find_insert(iff); 1674 if( prior ) { 1675 igvn->remove_dead_node(iff); 1676 iff = (IfNode*)prior; 1677 } else { 1678 // Cannot call transform on it just yet 1679 igvn->set_type_bottom(iff); 1680 } 1681 igvn->_worklist.push(iff); 1682 1683 // Now handle projections. Cloning not required. 1684 Node* new_if_f = (Node*)(new IfFalseNode( iff )); 1685 Node* new_if_t = (Node*)(new IfTrueNode ( iff )); 1686 1687 igvn->register_new_node_with_optimizer(new_if_f); 1688 igvn->register_new_node_with_optimizer(new_if_t); 1689 // Flip test, so flip trailing control 1690 igvn->replace_node(old_if_f, new_if_t); 1691 igvn->replace_node(old_if_t, new_if_f); 1692 1693 // Progress 1694 return iff; 1695 } 1696 1697 Node* RangeCheckNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1698 Node* res = Ideal_common(phase, can_reshape); 1699 if (res != NodeSentinel) { 1700 return res; 1701 } 1702 1703 PhaseIterGVN *igvn = phase->is_IterGVN(); 1704 // Setup to scan up the CFG looking for a dominating test 1705 Node* prev_dom = this; 1706 1707 // Check for range-check vs other kinds of tests 1708 Node* index1; 1709 Node* range1; 1710 jint offset1; 1711 int flip1 = is_range_check(range1, index1, offset1); 1712 if (flip1) { 1713 Node* dom = in(0); 1714 // Try to remove extra range checks. All 'up_one_dom' gives up at merges 1715 // so all checks we inspect post-dominate the top-most check we find. 1716 // If we are going to fail the current check and we reach the top check 1717 // then we are guaranteed to fail, so just start interpreting there. 1718 // We 'expand' the top 3 range checks to include all post-dominating 1719 // checks. 1720 1721 // The top 3 range checks seen 1722 const int NRC =3; 1723 RangeCheck prev_checks[NRC]; 1724 int nb_checks = 0; 1725 1726 // Low and high offsets seen so far 1727 jint off_lo = offset1; 1728 jint off_hi = offset1; 1729 1730 bool found_immediate_dominator = false; 1731 1732 // Scan for the top checks and collect range of offsets 1733 for (int dist = 0; dist < 999; dist++) { // Range-Check scan limit 1734 if (dom->Opcode() == Op_RangeCheck && // Not same opcode? 1735 prev_dom->in(0) == dom) { // One path of test does dominate? 1736 if (dom == this) return NULL; // dead loop 1737 // See if this is a range check 1738 Node* index2; 1739 Node* range2; 1740 jint offset2; 1741 int flip2 = dom->as_RangeCheck()->is_range_check(range2, index2, offset2); 1742 // See if this is a _matching_ range check, checking against 1743 // the same array bounds. 1744 if (flip2 == flip1 && range2 == range1 && index2 == index1 && 1745 dom->outcnt() == 2) { 1746 if (nb_checks == 0 && dom->in(1) == in(1)) { 1747 // Found an immediately dominating test at the same offset. 1748 // This kind of back-to-back test can be eliminated locally, 1749 // and there is no need to search further for dominating tests. 1750 assert(offset2 == offset1, "Same test but different offsets"); 1751 found_immediate_dominator = true; 1752 break; 1753 } 1754 // Gather expanded bounds 1755 off_lo = MIN2(off_lo,offset2); 1756 off_hi = MAX2(off_hi,offset2); 1757 // Record top NRC range checks 1758 prev_checks[nb_checks%NRC].ctl = prev_dom; 1759 prev_checks[nb_checks%NRC].off = offset2; 1760 nb_checks++; 1761 } 1762 } 1763 prev_dom = dom; 1764 dom = up_one_dom(dom); 1765 if (!dom) break; 1766 } 1767 1768 if (!found_immediate_dominator) { 1769 // Attempt to widen the dominating range check to cover some later 1770 // ones. Since range checks "fail" by uncommon-trapping to the 1771 // interpreter, widening a check can make us speculatively enter 1772 // the interpreter. If we see range-check deopt's, do not widen! 1773 if (!phase->C->allow_range_check_smearing()) return NULL; 1774 1775 // Didn't find prior covering check, so cannot remove anything. 1776 if (nb_checks == 0) { 1777 return NULL; 1778 } 1779 // Constant indices only need to check the upper bound. 1780 // Non-constant indices must check both low and high. 1781 int chk0 = (nb_checks - 1) % NRC; 1782 if (index1) { 1783 if (nb_checks == 1) { 1784 return NULL; 1785 } else { 1786 // If the top range check's constant is the min or max of 1787 // all constants we widen the next one to cover the whole 1788 // range of constants. 1789 RangeCheck rc0 = prev_checks[chk0]; 1790 int chk1 = (nb_checks - 2) % NRC; 1791 RangeCheck rc1 = prev_checks[chk1]; 1792 if (rc0.off == off_lo) { 1793 adjust_check(rc1.ctl, range1, index1, flip1, off_hi, igvn); 1794 prev_dom = rc1.ctl; 1795 } else if (rc0.off == off_hi) { 1796 adjust_check(rc1.ctl, range1, index1, flip1, off_lo, igvn); 1797 prev_dom = rc1.ctl; 1798 } else { 1799 // If the top test's constant is not the min or max of all 1800 // constants, we need 3 range checks. We must leave the 1801 // top test unchanged because widening it would allow the 1802 // accesses it protects to successfully read/write out of 1803 // bounds. 1804 if (nb_checks == 2) { 1805 return NULL; 1806 } 1807 int chk2 = (nb_checks - 3) % NRC; 1808 RangeCheck rc2 = prev_checks[chk2]; 1809 // The top range check a+i covers interval: -a <= i < length-a 1810 // The second range check b+i covers interval: -b <= i < length-b 1811 if (rc1.off <= rc0.off) { 1812 // if b <= a, we change the second range check to: 1813 // -min_of_all_constants <= i < length-min_of_all_constants 1814 // Together top and second range checks now cover: 1815 // -min_of_all_constants <= i < length-a 1816 // which is more restrictive than -b <= i < length-b: 1817 // -b <= -min_of_all_constants <= i < length-a <= length-b 1818 // The third check is then changed to: 1819 // -max_of_all_constants <= i < length-max_of_all_constants 1820 // so 2nd and 3rd checks restrict allowed values of i to: 1821 // -min_of_all_constants <= i < length-max_of_all_constants 1822 adjust_check(rc1.ctl, range1, index1, flip1, off_lo, igvn); 1823 adjust_check(rc2.ctl, range1, index1, flip1, off_hi, igvn); 1824 } else { 1825 // if b > a, we change the second range check to: 1826 // -max_of_all_constants <= i < length-max_of_all_constants 1827 // Together top and second range checks now cover: 1828 // -a <= i < length-max_of_all_constants 1829 // which is more restrictive than -b <= i < length-b: 1830 // -b < -a <= i < length-max_of_all_constants <= length-b 1831 // The third check is then changed to: 1832 // -max_of_all_constants <= i < length-max_of_all_constants 1833 // so 2nd and 3rd checks restrict allowed values of i to: 1834 // -min_of_all_constants <= i < length-max_of_all_constants 1835 adjust_check(rc1.ctl, range1, index1, flip1, off_hi, igvn); 1836 adjust_check(rc2.ctl, range1, index1, flip1, off_lo, igvn); 1837 } 1838 prev_dom = rc2.ctl; 1839 } 1840 } 1841 } else { 1842 RangeCheck rc0 = prev_checks[chk0]; 1843 // 'Widen' the offset of the 1st and only covering check 1844 adjust_check(rc0.ctl, range1, index1, flip1, off_hi, igvn); 1845 // Test is now covered by prior checks, dominate it out 1846 prev_dom = rc0.ctl; 1847 } 1848 } 1849 } else { 1850 prev_dom = search_identical(4); 1851 1852 if (prev_dom == NULL) { 1853 return NULL; 1854 } 1855 } 1856 1857 // Replace dominated IfNode 1858 return dominated_by(prev_dom, igvn); 1859 }