1 /* 2 * Copyright (c) 2000, 2015, 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 "opto/addnode.hpp" 29 #include "opto/castnode.hpp" 30 #include "opto/cfgnode.hpp" 31 #include "opto/connode.hpp" 32 #include "opto/loopnode.hpp" 33 #include "opto/phaseX.hpp" 34 #include "opto/runtime.hpp" 35 #include "opto/rootnode.hpp" 36 #include "opto/subnode.hpp" 37 38 // Portions of code courtesy of Clifford Click 39 40 // Optimization - Graph Style 41 42 43 extern int explicit_null_checks_elided; 44 45 //============================================================================= 46 //------------------------------Value------------------------------------------ 47 // Return a tuple for whichever arm of the IF is reachable 48 const Type *IfNode::Value( PhaseTransform *phase ) const { 49 if( !in(0) ) return Type::TOP; 50 if( phase->type(in(0)) == Type::TOP ) 51 return Type::TOP; 52 const Type *t = phase->type(in(1)); 53 if( t == Type::TOP ) // data is undefined 54 return TypeTuple::IFNEITHER; // unreachable altogether 55 if( t == TypeInt::ZERO ) // zero, or false 56 return TypeTuple::IFFALSE; // only false branch is reachable 57 if( t == TypeInt::ONE ) // 1, or true 58 return TypeTuple::IFTRUE; // only true branch is reachable 59 assert( t == TypeInt::BOOL, "expected boolean type" ); 60 61 return TypeTuple::IFBOTH; // No progress 62 } 63 64 const RegMask &IfNode::out_RegMask() const { 65 return RegMask::Empty; 66 } 67 68 //------------------------------split_if--------------------------------------- 69 // Look for places where we merge constants, then test on the merged value. 70 // If the IF test will be constant folded on the path with the constant, we 71 // win by splitting the IF to before the merge point. 72 static Node* split_if(IfNode *iff, PhaseIterGVN *igvn) { 73 // I could be a lot more general here, but I'm trying to squeeze this 74 // in before the Christmas '98 break so I'm gonna be kinda restrictive 75 // on the patterns I accept. CNC 76 77 // Look for a compare of a constant and a merged value 78 Node *i1 = iff->in(1); 79 if( !i1->is_Bool() ) return NULL; 80 BoolNode *b = i1->as_Bool(); 81 Node *cmp = b->in(1); 82 if( !cmp->is_Cmp() ) return NULL; 83 i1 = cmp->in(1); 84 if( i1 == NULL || !i1->is_Phi() ) return NULL; 85 PhiNode *phi = i1->as_Phi(); 86 if( phi->is_copy() ) return NULL; 87 Node *con2 = cmp->in(2); 88 if( !con2->is_Con() ) return NULL; 89 // See that the merge point contains some constants 90 Node *con1=NULL; 91 uint i4; 92 for( i4 = 1; i4 < phi->req(); i4++ ) { 93 con1 = phi->in(i4); 94 if( !con1 ) return NULL; // Do not optimize partially collapsed merges 95 if( con1->is_Con() ) break; // Found a constant 96 // Also allow null-vs-not-null checks 97 const TypePtr *tp = igvn->type(con1)->isa_ptr(); 98 if( tp && tp->_ptr == TypePtr::NotNull ) 99 break; 100 } 101 if( i4 >= phi->req() ) return NULL; // Found no constants 102 103 igvn->C->set_has_split_ifs(true); // Has chance for split-if 104 105 // Make sure that the compare can be constant folded away 106 Node *cmp2 = cmp->clone(); 107 cmp2->set_req(1,con1); 108 cmp2->set_req(2,con2); 109 const Type *t = cmp2->Value(igvn); 110 // This compare is dead, so whack it! 111 igvn->remove_dead_node(cmp2); 112 if( !t->singleton() ) return NULL; 113 114 // No intervening control, like a simple Call 115 Node *r = iff->in(0); 116 if( !r->is_Region() ) return NULL; 117 if( phi->region() != r ) return NULL; 118 // No other users of the cmp/bool 119 if (b->outcnt() != 1 || cmp->outcnt() != 1) { 120 //tty->print_cr("many users of cmp/bool"); 121 return NULL; 122 } 123 124 // Make sure we can determine where all the uses of merged values go 125 for (DUIterator_Fast jmax, j = r->fast_outs(jmax); j < jmax; j++) { 126 Node* u = r->fast_out(j); 127 if( u == r ) continue; 128 if( u == iff ) continue; 129 if( u->outcnt() == 0 ) continue; // use is dead & ignorable 130 if( !u->is_Phi() ) { 131 /* 132 if( u->is_Start() ) { 133 tty->print_cr("Region has inlined start use"); 134 } else { 135 tty->print_cr("Region has odd use"); 136 u->dump(2); 137 }*/ 138 return NULL; 139 } 140 if( u != phi ) { 141 // CNC - do not allow any other merged value 142 //tty->print_cr("Merging another value"); 143 //u->dump(2); 144 return NULL; 145 } 146 // Make sure we can account for all Phi uses 147 for (DUIterator_Fast kmax, k = u->fast_outs(kmax); k < kmax; k++) { 148 Node* v = u->fast_out(k); // User of the phi 149 // CNC - Allow only really simple patterns. 150 // In particular I disallow AddP of the Phi, a fairly common pattern 151 if (v == cmp) continue; // The compare is OK 152 if (v->is_ConstraintCast()) { 153 // If the cast is derived from data flow edges, it may not have a control edge. 154 // If so, it should be safe to split. But follow-up code can not deal with 155 // this (l. 359). So skip. 156 if (v->in(0) == NULL) { 157 return NULL; 158 } 159 if (v->in(0)->in(0) == iff) { 160 continue; // CastPP/II of the IfNode is OK 161 } 162 } 163 // Disabled following code because I cannot tell if exactly one 164 // path dominates without a real dominator check. CNC 9/9/1999 165 //uint vop = v->Opcode(); 166 //if( vop == Op_Phi ) { // Phi from another merge point might be OK 167 // Node *r = v->in(0); // Get controlling point 168 // if( !r ) return NULL; // Degraded to a copy 169 // // Find exactly one path in (either True or False doms, but not IFF) 170 // int cnt = 0; 171 // for( uint i = 1; i < r->req(); i++ ) 172 // if( r->in(i) && r->in(i)->in(0) == iff ) 173 // cnt++; 174 // if( cnt == 1 ) continue; // Exactly one of True or False guards Phi 175 //} 176 if( !v->is_Call() ) { 177 /* 178 if( v->Opcode() == Op_AddP ) { 179 tty->print_cr("Phi has AddP use"); 180 } else if( v->Opcode() == Op_CastPP ) { 181 tty->print_cr("Phi has CastPP use"); 182 } else if( v->Opcode() == Op_CastII ) { 183 tty->print_cr("Phi has CastII use"); 184 } else { 185 tty->print_cr("Phi has use I cant be bothered with"); 186 } 187 */ 188 } 189 return NULL; 190 191 /* CNC - Cut out all the fancy acceptance tests 192 // Can we clone this use when doing the transformation? 193 // If all uses are from Phis at this merge or constants, then YES. 194 if( !v->in(0) && v != cmp ) { 195 tty->print_cr("Phi has free-floating use"); 196 v->dump(2); 197 return NULL; 198 } 199 for( uint l = 1; l < v->req(); l++ ) { 200 if( (!v->in(l)->is_Phi() || v->in(l)->in(0) != r) && 201 !v->in(l)->is_Con() ) { 202 tty->print_cr("Phi has use"); 203 v->dump(2); 204 return NULL; 205 } // End of if Phi-use input is neither Phi nor Constant 206 } // End of for all inputs to Phi-use 207 */ 208 } // End of for all uses of Phi 209 } // End of for all uses of Region 210 211 // Only do this if the IF node is in a sane state 212 if (iff->outcnt() != 2) 213 return NULL; 214 215 // Got a hit! Do the Mondo Hack! 216 // 217 //ABC a1c def ghi B 1 e h A C a c d f g i 218 // R - Phi - Phi - Phi Rc - Phi - Phi - Phi Rx - Phi - Phi - Phi 219 // cmp - 2 cmp - 2 cmp - 2 220 // bool bool_c bool_x 221 // if if_c if_x 222 // T F T F T F 223 // ..s.. ..t .. ..s.. ..t.. ..s.. ..t.. 224 // 225 // Split the paths coming into the merge point into 2 separate groups of 226 // merges. On the left will be all the paths feeding constants into the 227 // Cmp's Phi. On the right will be the remaining paths. The Cmp's Phi 228 // will fold up into a constant; this will let the Cmp fold up as well as 229 // all the control flow. Below the original IF we have 2 control 230 // dependent regions, 's' and 't'. Now we will merge the two paths 231 // just prior to 's' and 't' from the two IFs. At least 1 path (and quite 232 // likely 2 or more) will promptly constant fold away. 233 PhaseGVN *phase = igvn; 234 235 // Make a region merging constants and a region merging the rest 236 uint req_c = 0; 237 Node* predicate_proj = NULL; 238 int nb_predicate_proj = 0; 239 for (uint ii = 1; ii < r->req(); ii++) { 240 if (phi->in(ii) == con1) { 241 req_c++; 242 } 243 Node* proj = PhaseIdealLoop::find_predicate(r->in(ii)); 244 if (proj != NULL) { 245 nb_predicate_proj++; 246 predicate_proj = proj; 247 } 248 } 249 if (nb_predicate_proj > 1) { 250 // Can happen in case of loop unswitching and when the loop is 251 // optimized out: it's not a loop anymore so we don't care about 252 // predicates. 253 assert(!r->is_Loop(), "this must not be a loop anymore"); 254 predicate_proj = NULL; 255 } 256 Node* predicate_c = NULL; 257 Node* predicate_x = NULL; 258 bool counted_loop = r->is_CountedLoop(); 259 260 Node *region_c = new RegionNode(req_c + 1); 261 Node *phi_c = con1; 262 uint len = r->req(); 263 Node *region_x = new RegionNode(len - req_c); 264 Node *phi_x = PhiNode::make_blank(region_x, phi); 265 for (uint i = 1, i_c = 1, i_x = 1; i < len; i++) { 266 if (phi->in(i) == con1) { 267 region_c->init_req( i_c++, r ->in(i) ); 268 if (r->in(i) == predicate_proj) 269 predicate_c = predicate_proj; 270 } else { 271 region_x->init_req( i_x, r ->in(i) ); 272 phi_x ->init_req( i_x++, phi->in(i) ); 273 if (r->in(i) == predicate_proj) 274 predicate_x = predicate_proj; 275 } 276 } 277 if (predicate_c != NULL && (req_c > 1)) { 278 assert(predicate_x == NULL, "only one predicate entry expected"); 279 predicate_c = NULL; // Do not clone predicate below merge point 280 } 281 if (predicate_x != NULL && ((len - req_c) > 2)) { 282 assert(predicate_c == NULL, "only one predicate entry expected"); 283 predicate_x = NULL; // Do not clone predicate below merge point 284 } 285 286 // Register the new RegionNodes but do not transform them. Cannot 287 // transform until the entire Region/Phi conglomerate has been hacked 288 // as a single huge transform. 289 igvn->register_new_node_with_optimizer( region_c ); 290 igvn->register_new_node_with_optimizer( region_x ); 291 // Prevent the untimely death of phi_x. Currently he has no uses. He is 292 // about to get one. If this only use goes away, then phi_x will look dead. 293 // However, he will be picking up some more uses down below. 294 Node *hook = new Node(4); 295 hook->init_req(0, phi_x); 296 hook->init_req(1, phi_c); 297 phi_x = phase->transform( phi_x ); 298 299 // Make the compare 300 Node *cmp_c = phase->makecon(t); 301 Node *cmp_x = cmp->clone(); 302 cmp_x->set_req(1,phi_x); 303 cmp_x->set_req(2,con2); 304 cmp_x = phase->transform(cmp_x); 305 // Make the bool 306 Node *b_c = phase->transform(new BoolNode(cmp_c,b->_test._test)); 307 Node *b_x = phase->transform(new BoolNode(cmp_x,b->_test._test)); 308 // Make the IfNode 309 IfNode *iff_c = new IfNode(region_c,b_c,iff->_prob,iff->_fcnt); 310 igvn->set_type_bottom(iff_c); 311 igvn->_worklist.push(iff_c); 312 hook->init_req(2, iff_c); 313 314 IfNode *iff_x = new IfNode(region_x,b_x,iff->_prob, iff->_fcnt); 315 igvn->set_type_bottom(iff_x); 316 igvn->_worklist.push(iff_x); 317 hook->init_req(3, iff_x); 318 319 // Make the true/false arms 320 Node *iff_c_t = phase->transform(new IfTrueNode (iff_c)); 321 Node *iff_c_f = phase->transform(new IfFalseNode(iff_c)); 322 if (predicate_c != NULL) { 323 assert(predicate_x == NULL, "only one predicate entry expected"); 324 // Clone loop predicates to each path 325 iff_c_t = igvn->clone_loop_predicates(predicate_c, iff_c_t, !counted_loop); 326 iff_c_f = igvn->clone_loop_predicates(predicate_c, iff_c_f, !counted_loop); 327 } 328 Node *iff_x_t = phase->transform(new IfTrueNode (iff_x)); 329 Node *iff_x_f = phase->transform(new IfFalseNode(iff_x)); 330 if (predicate_x != NULL) { 331 assert(predicate_c == NULL, "only one predicate entry expected"); 332 // Clone loop predicates to each path 333 iff_x_t = igvn->clone_loop_predicates(predicate_x, iff_x_t, !counted_loop); 334 iff_x_f = igvn->clone_loop_predicates(predicate_x, iff_x_f, !counted_loop); 335 } 336 337 // Merge the TRUE paths 338 Node *region_s = new RegionNode(3); 339 igvn->_worklist.push(region_s); 340 region_s->init_req(1, iff_c_t); 341 region_s->init_req(2, iff_x_t); 342 igvn->register_new_node_with_optimizer( region_s ); 343 344 // Merge the FALSE paths 345 Node *region_f = new RegionNode(3); 346 igvn->_worklist.push(region_f); 347 region_f->init_req(1, iff_c_f); 348 region_f->init_req(2, iff_x_f); 349 igvn->register_new_node_with_optimizer( region_f ); 350 351 igvn->hash_delete(cmp);// Remove soon-to-be-dead node from hash table. 352 cmp->set_req(1,NULL); // Whack the inputs to cmp because it will be dead 353 cmp->set_req(2,NULL); 354 // Check for all uses of the Phi and give them a new home. 355 // The 'cmp' got cloned, but CastPP/IIs need to be moved. 356 Node *phi_s = NULL; // do not construct unless needed 357 Node *phi_f = NULL; // do not construct unless needed 358 for (DUIterator_Last i2min, i2 = phi->last_outs(i2min); i2 >= i2min; --i2) { 359 Node* v = phi->last_out(i2);// User of the phi 360 igvn->rehash_node_delayed(v); // Have to fixup other Phi users 361 uint vop = v->Opcode(); 362 Node *proj = NULL; 363 if( vop == Op_Phi ) { // Remote merge point 364 Node *r = v->in(0); 365 for (uint i3 = 1; i3 < r->req(); i3++) 366 if (r->in(i3) && r->in(i3)->in(0) == iff) { 367 proj = r->in(i3); 368 break; 369 } 370 } else if( v->is_ConstraintCast() ) { 371 proj = v->in(0); // Controlling projection 372 } else { 373 assert( 0, "do not know how to handle this guy" ); 374 } 375 376 Node *proj_path_data, *proj_path_ctrl; 377 if( proj->Opcode() == Op_IfTrue ) { 378 if( phi_s == NULL ) { 379 // Only construct phi_s if needed, otherwise provides 380 // interfering use. 381 phi_s = PhiNode::make_blank(region_s,phi); 382 phi_s->init_req( 1, phi_c ); 383 phi_s->init_req( 2, phi_x ); 384 hook->add_req(phi_s); 385 phi_s = phase->transform(phi_s); 386 } 387 proj_path_data = phi_s; 388 proj_path_ctrl = region_s; 389 } else { 390 if( phi_f == NULL ) { 391 // Only construct phi_f if needed, otherwise provides 392 // interfering use. 393 phi_f = PhiNode::make_blank(region_f,phi); 394 phi_f->init_req( 1, phi_c ); 395 phi_f->init_req( 2, phi_x ); 396 hook->add_req(phi_f); 397 phi_f = phase->transform(phi_f); 398 } 399 proj_path_data = phi_f; 400 proj_path_ctrl = region_f; 401 } 402 403 // Fixup 'v' for for the split 404 if( vop == Op_Phi ) { // Remote merge point 405 uint i; 406 for( i = 1; i < v->req(); i++ ) 407 if( v->in(i) == phi ) 408 break; 409 v->set_req(i, proj_path_data ); 410 } else if( v->is_ConstraintCast() ) { 411 v->set_req(0, proj_path_ctrl ); 412 v->set_req(1, proj_path_data ); 413 } else 414 ShouldNotReachHere(); 415 } 416 417 // Now replace the original iff's True/False with region_s/region_t. 418 // This makes the original iff go dead. 419 for (DUIterator_Last i3min, i3 = iff->last_outs(i3min); i3 >= i3min; --i3) { 420 Node* p = iff->last_out(i3); 421 assert( p->Opcode() == Op_IfTrue || p->Opcode() == Op_IfFalse, "" ); 422 Node *u = (p->Opcode() == Op_IfTrue) ? region_s : region_f; 423 // Replace p with u 424 igvn->add_users_to_worklist(p); 425 for (DUIterator_Last lmin, l = p->last_outs(lmin); l >= lmin;) { 426 Node* x = p->last_out(l); 427 igvn->hash_delete(x); 428 uint uses_found = 0; 429 for( uint j = 0; j < x->req(); j++ ) { 430 if( x->in(j) == p ) { 431 x->set_req(j, u); 432 uses_found++; 433 } 434 } 435 l -= uses_found; // we deleted 1 or more copies of this edge 436 } 437 igvn->remove_dead_node(p); 438 } 439 440 // Force the original merge dead 441 igvn->hash_delete(r); 442 // First, remove region's dead users. 443 for (DUIterator_Last lmin, l = r->last_outs(lmin); l >= lmin;) { 444 Node* u = r->last_out(l); 445 if( u == r ) { 446 r->set_req(0, NULL); 447 } else { 448 assert(u->outcnt() == 0, "only dead users"); 449 igvn->remove_dead_node(u); 450 } 451 l -= 1; 452 } 453 igvn->remove_dead_node(r); 454 455 // Now remove the bogus extra edges used to keep things alive 456 igvn->remove_dead_node( hook ); 457 458 // Must return either the original node (now dead) or a new node 459 // (Do not return a top here, since that would break the uniqueness of top.) 460 return new ConINode(TypeInt::ZERO); 461 } 462 463 // if this IfNode follows a range check pattern return the projection 464 // for the failed path 465 ProjNode* IfNode::range_check_trap_proj(int& flip_test, Node*& l, Node*& r) { 466 Node* b = in(1); 467 if (b == NULL || !b->is_Bool()) return NULL; 468 BoolNode* bn = b->as_Bool(); 469 Node* cmp = bn->in(1); 470 if (cmp == NULL) return NULL; 471 if (cmp->Opcode() != Op_CmpU) return NULL; 472 473 l = cmp->in(1); 474 r = cmp->in(2); 475 flip_test = 1; 476 if (bn->_test._test == BoolTest::le) { 477 l = cmp->in(2); 478 r = cmp->in(1); 479 flip_test = 2; 480 } else if (bn->_test._test != BoolTest::lt) { 481 return NULL; 482 } 483 if (l->is_top()) return NULL; // Top input means dead test 484 if (r->Opcode() != Op_LoadRange) return NULL; 485 486 // We have recognized one of these forms: 487 // Flip 1: If (Bool[<] CmpU(l, LoadRange)) ... 488 // Flip 2: If (Bool[<=] CmpU(LoadRange, l)) ... 489 490 ProjNode* iftrap = proj_out(flip_test == 2 ? true : false); 491 return iftrap; 492 } 493 494 495 //------------------------------is_range_check--------------------------------- 496 // Return 0 if not a range check. Return 1 if a range check and set index and 497 // offset. Return 2 if we had to negate the test. Index is NULL if the check 498 // is versus a constant. 499 int IfNode::is_range_check(Node* &range, Node* &index, jint &offset) { 500 int flip_test = 0; 501 Node* l = NULL; 502 Node* r = NULL; 503 ProjNode* iftrap = range_check_trap_proj(flip_test, l, r); 504 505 if (iftrap == NULL) { 506 return 0; 507 } 508 509 // Make sure it's a real range check by requiring an uncommon trap 510 // along the OOB path. Otherwise, it's possible that the user wrote 511 // something which optimized to look like a range check but behaves 512 // in some other way. 513 if (iftrap->is_uncommon_trap_proj(Deoptimization::Reason_range_check) == NULL) { 514 return 0; 515 } 516 517 // Look for index+offset form 518 Node* ind = l; 519 jint off = 0; 520 if (l->is_top()) { 521 return 0; 522 } else if (l->Opcode() == Op_AddI) { 523 if ((off = l->in(1)->find_int_con(0)) != 0) { 524 ind = l->in(2); 525 } else if ((off = l->in(2)->find_int_con(0)) != 0) { 526 ind = l->in(1); 527 } 528 } else if ((off = l->find_int_con(-1)) >= 0) { 529 // constant offset with no variable index 530 ind = NULL; 531 } else { 532 // variable index with no constant offset (or dead negative index) 533 off = 0; 534 } 535 536 // Return all the values: 537 index = ind; 538 offset = off; 539 range = r; 540 return flip_test; 541 } 542 543 //------------------------------adjust_check----------------------------------- 544 // Adjust (widen) a prior range check 545 static void adjust_check(Node* proj, Node* range, Node* index, 546 int flip, jint off_lo, PhaseIterGVN* igvn) { 547 PhaseGVN *gvn = igvn; 548 // Break apart the old check 549 Node *iff = proj->in(0); 550 Node *bol = iff->in(1); 551 if( bol->is_top() ) return; // In case a partially dead range check appears 552 // bail (or bomb[ASSERT/DEBUG]) if NOT projection-->IfNode-->BoolNode 553 DEBUG_ONLY( if( !bol->is_Bool() ) { proj->dump(3); fatal("Expect projection-->IfNode-->BoolNode"); } ) 554 if( !bol->is_Bool() ) return; 555 556 Node *cmp = bol->in(1); 557 // Compute a new check 558 Node *new_add = gvn->intcon(off_lo); 559 if( index ) { 560 new_add = off_lo ? gvn->transform(new AddINode( index, new_add )) : index; 561 } 562 Node *new_cmp = (flip == 1) 563 ? new CmpUNode( new_add, range ) 564 : new CmpUNode( range, new_add ); 565 new_cmp = gvn->transform(new_cmp); 566 // See if no need to adjust the existing check 567 if( new_cmp == cmp ) return; 568 // Else, adjust existing check 569 Node *new_bol = gvn->transform( new BoolNode( new_cmp, bol->as_Bool()->_test._test ) ); 570 igvn->rehash_node_delayed( iff ); 571 iff->set_req_X( 1, new_bol, igvn ); 572 } 573 574 //------------------------------up_one_dom------------------------------------- 575 // Walk up the dominator tree one step. Return NULL at root or true 576 // complex merges. Skips through small diamonds. 577 Node* IfNode::up_one_dom(Node *curr, bool linear_only) { 578 Node *dom = curr->in(0); 579 if( !dom ) // Found a Region degraded to a copy? 580 return curr->nonnull_req(); // Skip thru it 581 582 if( curr != dom ) // Normal walk up one step? 583 return dom; 584 585 // Use linear_only if we are still parsing, since we cannot 586 // trust the regions to be fully filled in. 587 if (linear_only) 588 return NULL; 589 590 if( dom->is_Root() ) 591 return NULL; 592 593 // Else hit a Region. Check for a loop header 594 if( dom->is_Loop() ) 595 return dom->in(1); // Skip up thru loops 596 597 // Check for small diamonds 598 Node *din1, *din2, *din3, *din4; 599 if( dom->req() == 3 && // 2-path merge point 600 (din1 = dom ->in(1)) && // Left path exists 601 (din2 = dom ->in(2)) && // Right path exists 602 (din3 = din1->in(0)) && // Left path up one 603 (din4 = din2->in(0)) ) { // Right path up one 604 if( din3->is_Call() && // Handle a slow-path call on either arm 605 (din3 = din3->in(0)) ) 606 din3 = din3->in(0); 607 if( din4->is_Call() && // Handle a slow-path call on either arm 608 (din4 = din4->in(0)) ) 609 din4 = din4->in(0); 610 if( din3 == din4 && din3->is_If() ) 611 return din3; // Skip around diamonds 612 } 613 614 // Give up the search at true merges 615 return NULL; // Dead loop? Or hit root? 616 } 617 618 619 //------------------------------filtered_int_type-------------------------------- 620 // Return a possibly more restrictive type for val based on condition control flow for an if 621 const TypeInt* IfNode::filtered_int_type(PhaseGVN* gvn, Node *val, Node* if_proj) { 622 assert(if_proj && 623 (if_proj->Opcode() == Op_IfTrue || if_proj->Opcode() == Op_IfFalse), "expecting an if projection"); 624 if (if_proj->in(0) && if_proj->in(0)->is_If()) { 625 IfNode* iff = if_proj->in(0)->as_If(); 626 if (iff->in(1) && iff->in(1)->is_Bool()) { 627 BoolNode* bol = iff->in(1)->as_Bool(); 628 if (bol->in(1) && bol->in(1)->is_Cmp()) { 629 const CmpNode* cmp = bol->in(1)->as_Cmp(); 630 if (cmp->in(1) == val) { 631 const TypeInt* cmp2_t = gvn->type(cmp->in(2))->isa_int(); 632 if (cmp2_t != NULL) { 633 jint lo = cmp2_t->_lo; 634 jint hi = cmp2_t->_hi; 635 BoolTest::mask msk = if_proj->Opcode() == Op_IfTrue ? bol->_test._test : bol->_test.negate(); 636 switch (msk) { 637 case BoolTest::ne: 638 // Can't refine type 639 return NULL; 640 case BoolTest::eq: 641 return cmp2_t; 642 case BoolTest::lt: 643 lo = TypeInt::INT->_lo; 644 if (hi - 1 < hi) { 645 hi = hi - 1; 646 } 647 break; 648 case BoolTest::le: 649 lo = TypeInt::INT->_lo; 650 break; 651 case BoolTest::gt: 652 if (lo + 1 > lo) { 653 lo = lo + 1; 654 } 655 hi = TypeInt::INT->_hi; 656 break; 657 case BoolTest::ge: 658 // lo unchanged 659 hi = TypeInt::INT->_hi; 660 break; 661 } 662 const TypeInt* rtn_t = TypeInt::make(lo, hi, cmp2_t->_widen); 663 return rtn_t; 664 } 665 } 666 } 667 } 668 } 669 return NULL; 670 } 671 672 //------------------------------fold_compares---------------------------- 673 // See if a pair of CmpIs can be converted into a CmpU. In some cases 674 // the direction of this if is determined by the preceding if so it 675 // can be eliminate entirely. 676 // 677 // Given an if testing (CmpI n v) check for an immediately control 678 // dependent if that is testing (CmpI n v2) and has one projection 679 // leading to this if and the other projection leading to a region 680 // that merges one of this ifs control projections. 681 // 682 // If 683 // / | 684 // / | 685 // / | 686 // If | 687 // /\ | 688 // / \ | 689 // / \ | 690 // / Region 691 // 692 // Or given an if testing (CmpI n v) check for a dominating if that is 693 // testing (CmpI n v2), both having one projection leading to an 694 // uncommon trap. Allow Another independent guard in between to cover 695 // an explicit range check: 696 // if (index < 0 || index >= array.length) { 697 // which may need a null check to guard the LoadRange 698 // 699 // If 700 // / \ 701 // / \ 702 // / \ 703 // If unc 704 // /\ 705 // / \ 706 // / \ 707 // / unc 708 // 709 710 // Is the comparison for this If suitable for folding? 711 bool IfNode::cmpi_folds(PhaseIterGVN* igvn) { 712 return in(1) != NULL && 713 in(1)->is_Bool() && 714 in(1)->in(1) != NULL && 715 in(1)->in(1)->Opcode() == Op_CmpI && 716 in(1)->in(1)->in(2) != NULL && 717 in(1)->in(1)->in(2) != igvn->C->top() && 718 (in(1)->as_Bool()->_test.is_less() || 719 in(1)->as_Bool()->_test.is_greater()); 720 } 721 722 // Is a dominating control suitable for folding with this if? 723 bool IfNode::is_ctrl_folds(Node* ctrl, PhaseIterGVN* igvn) { 724 return ctrl != NULL && 725 ctrl->is_Proj() && 726 ctrl->in(0) != NULL && 727 ctrl->in(0)->is_If() && 728 ctrl->in(0)->outcnt() == 2 && 729 ctrl->in(0)->as_If()->cmpi_folds(igvn) && 730 // Must compare same value 731 ctrl->in(0)->in(1)->in(1)->in(1) != NULL && 732 ctrl->in(0)->in(1)->in(1)->in(1) == in(1)->in(1)->in(1); 733 } 734 735 // Do this If and the dominating If share a region? 736 bool IfNode::has_shared_region(ProjNode* proj, ProjNode*& success, ProjNode*& fail) { 737 ProjNode* otherproj = proj->other_if_proj(); 738 Node* otherproj_ctrl_use = otherproj->unique_ctrl_out(); 739 RegionNode* region = (otherproj_ctrl_use != NULL && otherproj_ctrl_use->is_Region()) ? otherproj_ctrl_use->as_Region() : NULL; 740 success = NULL; 741 fail = NULL; 742 743 if (otherproj->outcnt() == 1 && region != NULL && !region->has_phi()) { 744 for (int i = 0; i < 2; i++) { 745 ProjNode* proj = proj_out(i); 746 if (success == NULL && proj->outcnt() == 1 && proj->unique_out() == region) { 747 success = proj; 748 } else if (fail == NULL) { 749 fail = proj; 750 } else { 751 success = fail = NULL; 752 } 753 } 754 } 755 return success != NULL && fail != NULL; 756 } 757 758 // Return projection that leads to an uncommon trap if any 759 ProjNode* IfNode::uncommon_trap_proj(CallStaticJavaNode*& call) const { 760 for (int i = 0; i < 2; i++) { 761 call = proj_out(i)->is_uncommon_trap_proj(Deoptimization::Reason_none); 762 if (call != NULL) { 763 return proj_out(i); 764 } 765 } 766 return NULL; 767 } 768 769 // Do this If and the dominating If both branch out to an uncommon trap 770 bool IfNode::has_only_uncommon_traps(ProjNode* proj, ProjNode*& success, ProjNode*& fail, PhaseIterGVN* igvn) { 771 ProjNode* otherproj = proj->other_if_proj(); 772 // Dominating uncommon trap must have 'Reason_unstable_if' to ensure re-execution of folded Ifs 773 CallStaticJavaNode* dom_unc = otherproj->is_uncommon_trap_proj(Deoptimization::Reason_unstable_if); 774 775 if (otherproj->outcnt() == 1 && dom_unc != NULL) { 776 CallStaticJavaNode* unc = NULL; 777 ProjNode* unc_proj = uncommon_trap_proj(unc); 778 if (unc_proj != NULL && unc_proj->outcnt() == 1) { 779 if (dom_unc == unc) { 780 // Allow the uncommon trap to be shared through a region 781 RegionNode* r = unc->in(0)->as_Region(); 782 if (r->outcnt() != 2 || r->req() != 3 || r->find_edge(otherproj) == -1 || r->find_edge(unc_proj) == -1) { 783 return false; 784 } 785 assert(r->has_phi() == NULL, "simple region shouldn't have a phi"); 786 } else if (dom_unc->in(0) != otherproj || unc->in(0) != unc_proj) { 787 return false; 788 } 789 790 // Check if the bci of the dominating uncommon trap dominates the bci 791 // of the dominated uncommon trap. Otherwise we may not re-execute 792 // the dominated check after deoptimization from the merged uncommon trap. 793 ciMethod* method = unc->jvms()->method(); 794 ciMethod* dom_method = dom_unc->jvms()->method(); 795 if (method != dom_method) { 796 return false; 797 } 798 ciTypeFlow* flow = dom_method->get_flow_analysis(); 799 int bci = unc->jvms()->bci(); 800 int dom_bci = dom_unc->jvms()->bci(); 801 if (!flow->is_dominated_by(bci, dom_bci)) { 802 return false; 803 } 804 805 // See merge_uncommon_traps: the reason of the uncommon trap 806 // will be changed and the state of the dominating If will be 807 // used. Checked that we didn't apply this transformation in a 808 // previous compilation and it didn't cause too many traps 809 if (!igvn->C->too_many_traps(dom_method, dom_bci, Deoptimization::Reason_unstable_fused_if) && 810 !igvn->C->too_many_traps(dom_method, dom_bci, Deoptimization::Reason_range_check)) { 811 success = unc_proj; 812 fail = unc_proj->other_if_proj(); 813 return true; 814 } 815 } 816 } 817 return false; 818 } 819 820 // Check that the 2 CmpI can be folded into as single CmpU and proceed with the folding 821 bool IfNode::fold_compares_helper(ProjNode* proj, ProjNode* success, ProjNode* fail, PhaseIterGVN* igvn) { 822 Node* this_cmp = in(1)->in(1); 823 BoolNode* this_bool = in(1)->as_Bool(); 824 IfNode* dom_iff = proj->in(0)->as_If(); 825 BoolNode* dom_bool = dom_iff->in(1)->as_Bool(); 826 Node* lo = dom_iff->in(1)->in(1)->in(2); 827 Node* hi = this_cmp->in(2); 828 Node* n = this_cmp->in(1); 829 ProjNode* otherproj = proj->other_if_proj(); 830 831 const TypeInt* lo_type = IfNode::filtered_int_type(igvn, n, otherproj); 832 const TypeInt* hi_type = IfNode::filtered_int_type(igvn, n, success); 833 834 BoolTest::mask lo_test = dom_bool->_test._test; 835 BoolTest::mask hi_test = this_bool->_test._test; 836 BoolTest::mask cond = hi_test; 837 838 // convert: 839 // 840 // dom_bool = x {<,<=,>,>=} a 841 // / \ 842 // proj = {True,False} / \ otherproj = {False,True} 843 // / 844 // this_bool = x {<,<=} b 845 // / \ 846 // fail = {True,False} / \ success = {False,True} 847 // / 848 // 849 // (Second test guaranteed canonicalized, first one may not have 850 // been canonicalized yet) 851 // 852 // into: 853 // 854 // cond = (x - lo) {<u,<=u,>u,>=u} adjusted_lim 855 // / \ 856 // fail / \ success 857 // / 858 // 859 860 // Figure out which of the two tests sets the upper bound and which 861 // sets the lower bound if any. 862 Node* adjusted_lim = NULL; 863 if (hi_type->_lo > lo_type->_hi && hi_type->_hi == max_jint && lo_type->_lo == min_jint) { 864 assert((dom_bool->_test.is_less() && !proj->_con) || 865 (dom_bool->_test.is_greater() && proj->_con), "incorrect test"); 866 // this test was canonicalized 867 assert(this_bool->_test.is_less() && fail->_con, "incorrect test"); 868 869 // this_bool = < 870 // dom_bool = >= (proj = True) or dom_bool = < (proj = False) 871 // x in [a, b[ on the fail (= True) projection, b > a-1 (because of hi_type->_lo > lo_type->_hi test above): 872 // lo = a, hi = b, adjusted_lim = b-a, cond = <u 873 // dom_bool = > (proj = True) or dom_bool = <= (proj = False) 874 // x in ]a, b[ on the fail (= True) projection, b > a: 875 // lo = a+1, hi = b, adjusted_lim = b-a-1, cond = <u 876 // this_bool = <= 877 // dom_bool = >= (proj = True) or dom_bool = < (proj = False) 878 // x in [a, b] on the fail (= True) projection, b+1 > a-1: 879 // lo = a, hi = b, adjusted_lim = b-a+1, cond = <u 880 // lo = a, hi = b, adjusted_lim = b-a, cond = <=u doesn't work because b = a - 1 is possible, then b-a = -1 881 // dom_bool = > (proj = True) or dom_bool = <= (proj = False) 882 // x in ]a, b] on the fail (= True) projection b+1 > a: 883 // lo = a+1, hi = b, adjusted_lim = b-a, cond = <u 884 // lo = a+1, hi = b, adjusted_lim = b-a-1, cond = <=u doesn't work because a = b is possible, then b-a-1 = -1 885 886 if (hi_test == BoolTest::lt) { 887 if (lo_test == BoolTest::gt || lo_test == BoolTest::le) { 888 lo = igvn->transform(new AddINode(lo, igvn->intcon(1))); 889 } 890 } else { 891 assert(hi_test == BoolTest::le, "bad test"); 892 if (lo_test == BoolTest::ge || lo_test == BoolTest::lt) { 893 adjusted_lim = igvn->transform(new SubINode(hi, lo)); 894 adjusted_lim = igvn->transform(new AddINode(adjusted_lim, igvn->intcon(1))); 895 cond = BoolTest::lt; 896 } else { 897 assert(lo_test == BoolTest::gt || lo_test == BoolTest::le, "bad test"); 898 adjusted_lim = igvn->transform(new SubINode(hi, lo)); 899 lo = igvn->transform(new AddINode(lo, igvn->intcon(1))); 900 cond = BoolTest::lt; 901 } 902 } 903 } else if (lo_type->_lo > hi_type->_hi && lo_type->_hi == max_jint && hi_type->_lo == min_jint) { 904 905 // this_bool = < 906 // dom_bool = < (proj = True) or dom_bool = >= (proj = False) 907 // x in [b, a[ on the fail (= False) projection, a > b-1 (because of lo_type->_lo > hi_type->_hi above): 908 // lo = b, hi = a, adjusted_lim = a-b, cond = >=u 909 // dom_bool = <= (proj = True) or dom_bool = > (proj = False) 910 // x in [b, a] on the fail (= False) projection, a+1 > b-1: 911 // lo = b, hi = a, adjusted_lim = a-b+1, cond = >=u 912 // lo = b, hi = a, adjusted_lim = a-b, cond = >u doesn't work because a = b - 1 is possible, then b-a = -1 913 // this_bool = <= 914 // dom_bool = < (proj = True) or dom_bool = >= (proj = False) 915 // x in ]b, a[ on the fail (= False) projection, a > b: 916 // lo = b+1, hi = a, adjusted_lim = a-b-1, cond = >=u 917 // dom_bool = <= (proj = True) or dom_bool = > (proj = False) 918 // x in ]b, a] on the fail (= False) projection, a+1 > b: 919 // lo = b+1, hi = a, adjusted_lim = a-b, cond = >=u 920 // lo = b+1, hi = a, adjusted_lim = a-b-1, cond = >u doesn't work because a = b is possible, then b-a-1 = -1 921 922 swap(lo, hi); 923 swap(lo_type, hi_type); 924 swap(lo_test, hi_test); 925 926 assert((dom_bool->_test.is_less() && proj->_con) || 927 (dom_bool->_test.is_greater() && !proj->_con), "incorrect test"); 928 // this test was canonicalized 929 assert(this_bool->_test.is_less() && !fail->_con, "incorrect test"); 930 931 cond = (hi_test == BoolTest::le || hi_test == BoolTest::gt) ? BoolTest::gt : BoolTest::ge; 932 933 if (lo_test == BoolTest::lt) { 934 if (hi_test == BoolTest::lt || hi_test == BoolTest::ge) { 935 cond = BoolTest::ge; 936 } else { 937 assert(hi_test == BoolTest::le || hi_test == BoolTest::gt, "bad test"); 938 adjusted_lim = igvn->transform(new SubINode(hi, lo)); 939 adjusted_lim = igvn->transform(new AddINode(adjusted_lim, igvn->intcon(1))); 940 cond = BoolTest::ge; 941 } 942 } else if (lo_test == BoolTest::le) { 943 if (hi_test == BoolTest::lt || hi_test == BoolTest::ge) { 944 lo = igvn->transform(new AddINode(lo, igvn->intcon(1))); 945 cond = BoolTest::ge; 946 } else { 947 assert(hi_test == BoolTest::le || hi_test == BoolTest::gt, "bad test"); 948 adjusted_lim = igvn->transform(new SubINode(hi, lo)); 949 lo = igvn->transform(new AddINode(lo, igvn->intcon(1))); 950 cond = BoolTest::ge; 951 } 952 } 953 } else { 954 const TypeInt* failtype = filtered_int_type(igvn, n, proj); 955 if (failtype != NULL) { 956 const TypeInt* type2 = filtered_int_type(igvn, n, fail); 957 if (type2 != NULL) { 958 failtype = failtype->join(type2)->is_int(); 959 if (failtype->_lo > failtype->_hi) { 960 // previous if determines the result of this if so 961 // replace Bool with constant 962 igvn->hash_delete(this); 963 set_req(1, igvn->intcon(success->_con)); 964 return true; 965 } 966 } 967 } 968 lo = NULL; 969 hi = NULL; 970 } 971 972 if (lo && hi) { 973 // Merge the two compares into a single unsigned compare by building (CmpU (n - lo) (hi - lo)) 974 Node* adjusted_val = igvn->transform(new SubINode(n, lo)); 975 if (adjusted_lim == NULL) { 976 adjusted_lim = igvn->transform(new SubINode(hi, lo)); 977 } 978 Node* newcmp = igvn->transform(new CmpUNode(adjusted_val, adjusted_lim)); 979 Node* newbool = igvn->transform(new BoolNode(newcmp, cond)); 980 981 igvn->replace_input_of(dom_iff, 1, igvn->intcon(proj->_con)); 982 set_req(1, newbool); 983 984 return true; 985 } 986 return false; 987 } 988 989 // Merge the branches that trap for this If and the dominating If into 990 // a single region that branches to the uncommon trap for the 991 // dominating If 992 void IfNode::merge_uncommon_traps(ProjNode* proj, ProjNode* success, ProjNode* fail, PhaseIterGVN* igvn) { 993 ProjNode* otherproj = proj->other_if_proj(); 994 995 CallStaticJavaNode* unc = success->is_uncommon_trap_proj(Deoptimization::Reason_none); 996 CallStaticJavaNode* dom_unc = otherproj->is_uncommon_trap_proj(Deoptimization::Reason_none); 997 998 if (unc != dom_unc) { 999 Node* r = new RegionNode(3); 1000 1001 r->set_req(1, otherproj); 1002 r->set_req(2, success); 1003 r = igvn->transform(r); 1004 assert(r->is_Region(), "can't go away"); 1005 1006 // Make both If trap at the state of the first If: once the CmpI 1007 // nodes are merged, if we trap we don't know which of the CmpI 1008 // nodes would have caused the trap so we have to restart 1009 // execution at the first one 1010 igvn->replace_input_of(dom_unc, 0, r); 1011 igvn->replace_input_of(unc, 0, igvn->C->top()); 1012 } 1013 int trap_request = dom_unc->uncommon_trap_request(); 1014 Deoptimization::DeoptReason reason = Deoptimization::trap_request_reason(trap_request); 1015 Deoptimization::DeoptAction action = Deoptimization::trap_request_action(trap_request); 1016 1017 int flip_test = 0; 1018 Node* l = NULL; 1019 Node* r = NULL; 1020 1021 if (success->in(0)->as_If()->range_check_trap_proj(flip_test, l, r) != NULL) { 1022 // If this looks like a range check, change the trap to 1023 // Reason_range_check so the compiler recognizes it as a range 1024 // check and applies the corresponding optimizations 1025 trap_request = Deoptimization::make_trap_request(Deoptimization::Reason_range_check, action); 1026 1027 improve_address_types(l, r, fail, igvn); 1028 } else if (unc != dom_unc) { 1029 // If we trap we won't know what CmpI would have caused the trap 1030 // so use a special trap reason to mark this pair of CmpI nodes as 1031 // bad candidate for folding. On recompilation we won't fold them 1032 // and we may trap again but this time we'll know what branch 1033 // traps 1034 trap_request = Deoptimization::make_trap_request(Deoptimization::Reason_unstable_fused_if, action); 1035 } 1036 igvn->replace_input_of(dom_unc, TypeFunc::Parms, igvn->intcon(trap_request)); 1037 } 1038 1039 // If we are turning 2 CmpI nodes into a CmpU that follows the pattern 1040 // of a rangecheck on index i, on 64 bit the compares may be followed 1041 // by memory accesses using i as index. In that case, the CmpU tells 1042 // us something about the values taken by i that can help the compiler 1043 // (see Compile::conv_I2X_index()) 1044 void IfNode::improve_address_types(Node* l, Node* r, ProjNode* fail, PhaseIterGVN* igvn) { 1045 #ifdef _LP64 1046 ResourceMark rm; 1047 Node_Stack stack(2); 1048 1049 assert(r->Opcode() == Op_LoadRange, "unexpected range check"); 1050 const TypeInt* array_size = igvn->type(r)->is_int(); 1051 1052 stack.push(l, 0); 1053 1054 while(stack.size() > 0) { 1055 Node* n = stack.node(); 1056 uint start = stack.index(); 1057 1058 uint i = start; 1059 for (; i < n->outcnt(); i++) { 1060 Node* use = n->raw_out(i); 1061 if (stack.size() == 1) { 1062 if (use->Opcode() == Op_ConvI2L) { 1063 const TypeLong* bounds = use->as_Type()->type()->is_long(); 1064 if (bounds->_lo <= array_size->_lo && bounds->_hi >= array_size->_hi && 1065 (bounds->_lo != array_size->_lo || bounds->_hi != array_size->_hi)) { 1066 stack.set_index(i+1); 1067 stack.push(use, 0); 1068 break; 1069 } 1070 } 1071 } else if (use->is_Mem()) { 1072 Node* ctrl = use->in(0); 1073 for (int i = 0; i < 10 && ctrl != NULL && ctrl != fail; i++) { 1074 ctrl = up_one_dom(ctrl); 1075 } 1076 if (ctrl == fail) { 1077 Node* init_n = stack.node_at(1); 1078 assert(init_n->Opcode() == Op_ConvI2L, "unexpected first node"); 1079 Node* new_n = igvn->C->conv_I2X_index(igvn, l, array_size); 1080 1081 // The type of the ConvI2L may be widen and so the new 1082 // ConvI2L may not be better than an existing ConvI2L 1083 if (new_n != init_n) { 1084 for (uint j = 2; j < stack.size(); j++) { 1085 Node* n = stack.node_at(j); 1086 Node* clone = n->clone(); 1087 int rep = clone->replace_edge(init_n, new_n); 1088 assert(rep > 0, "can't find expected node?"); 1089 clone = igvn->transform(clone); 1090 init_n = n; 1091 new_n = clone; 1092 } 1093 igvn->hash_delete(use); 1094 int rep = use->replace_edge(init_n, new_n); 1095 assert(rep > 0, "can't find expected node?"); 1096 igvn->transform(use); 1097 if (init_n->outcnt() == 0) { 1098 igvn->_worklist.push(init_n); 1099 } 1100 } 1101 } 1102 } else if (use->in(0) == NULL && (igvn->type(use)->isa_long() || 1103 igvn->type(use)->isa_ptr())) { 1104 stack.set_index(i+1); 1105 stack.push(use, 0); 1106 break; 1107 } 1108 } 1109 if (i == n->outcnt()) { 1110 stack.pop(); 1111 } 1112 } 1113 #endif 1114 } 1115 1116 bool IfNode::is_cmp_with_loadrange(ProjNode* proj) { 1117 if (in(1) != NULL && 1118 in(1)->in(1) != NULL && 1119 in(1)->in(1)->in(2) != NULL) { 1120 Node* other = in(1)->in(1)->in(2); 1121 if (other->Opcode() == Op_LoadRange && 1122 ((other->in(0) != NULL && other->in(0) == proj) || 1123 (other->in(0) == NULL && 1124 other->in(2) != NULL && 1125 other->in(2)->is_AddP() && 1126 other->in(2)->in(1) != NULL && 1127 other->in(2)->in(1)->Opcode() == Op_CastPP && 1128 other->in(2)->in(1)->in(0) == proj))) { 1129 return true; 1130 } 1131 } 1132 return false; 1133 } 1134 1135 bool IfNode::is_null_check(ProjNode* proj, PhaseIterGVN* igvn) { 1136 Node* other = in(1)->in(1)->in(2); 1137 if (other->in(MemNode::Address) != NULL && 1138 proj->in(0)->in(1) != NULL && 1139 proj->in(0)->in(1)->is_Bool() && 1140 proj->in(0)->in(1)->in(1) != NULL && 1141 proj->in(0)->in(1)->in(1)->Opcode() == Op_CmpP && 1142 proj->in(0)->in(1)->in(1)->in(2) != NULL && 1143 proj->in(0)->in(1)->in(1)->in(1) == other->in(MemNode::Address)->in(AddPNode::Address)->uncast() && 1144 igvn->type(proj->in(0)->in(1)->in(1)->in(2)) == TypePtr::NULL_PTR) { 1145 return true; 1146 } 1147 return false; 1148 } 1149 1150 // Check that the If that is in between the 2 integer comparisons has 1151 // no side effect 1152 bool IfNode::is_side_effect_free_test(ProjNode* proj, PhaseIterGVN* igvn) { 1153 if (proj != NULL && 1154 proj->is_uncommon_trap_if_pattern(Deoptimization::Reason_none) && 1155 proj->outcnt() <= 2) { 1156 if (proj->outcnt() == 1 || 1157 // Allow simple null check from LoadRange 1158 (is_cmp_with_loadrange(proj) && is_null_check(proj, igvn))) { 1159 CallStaticJavaNode* unc = proj->is_uncommon_trap_if_pattern(Deoptimization::Reason_none); 1160 CallStaticJavaNode* dom_unc = proj->in(0)->in(0)->as_Proj()->is_uncommon_trap_if_pattern(Deoptimization::Reason_none); 1161 1162 // reroute_side_effect_free_unc changes the state of this 1163 // uncommon trap to restart execution at the previous 1164 // CmpI. Check that this change in a previous compilation didn't 1165 // cause too many traps. 1166 int trap_request = unc->uncommon_trap_request(); 1167 Deoptimization::DeoptReason reason = Deoptimization::trap_request_reason(trap_request); 1168 1169 if (igvn->C->too_many_traps(dom_unc->jvms()->method(), dom_unc->jvms()->bci(), reason)) { 1170 return false; 1171 } 1172 1173 return true; 1174 } 1175 } 1176 return false; 1177 } 1178 1179 // Make the If between the 2 integer comparisons trap at the state of 1180 // the first If: the last CmpI is the one replaced by a CmpU and the 1181 // first CmpI is eliminated, so the test between the 2 CmpI nodes 1182 // won't be guarded by the first CmpI anymore. It can trap in cases 1183 // where the first CmpI would have prevented it from executing: on a 1184 // trap, we need to restart execution at the state of the first CmpI 1185 void IfNode::reroute_side_effect_free_unc(ProjNode* proj, ProjNode* dom_proj, PhaseIterGVN* igvn) { 1186 CallStaticJavaNode* dom_unc = dom_proj->is_uncommon_trap_if_pattern(Deoptimization::Reason_none); 1187 ProjNode* otherproj = proj->other_if_proj(); 1188 CallStaticJavaNode* unc = proj->is_uncommon_trap_if_pattern(Deoptimization::Reason_none); 1189 Node* call_proj = dom_unc->unique_ctrl_out(); 1190 Node* halt = call_proj->unique_ctrl_out(); 1191 1192 Node* new_unc = dom_unc->clone(); 1193 call_proj = call_proj->clone(); 1194 halt = halt->clone(); 1195 Node* c = otherproj->clone(); 1196 1197 c = igvn->transform(c); 1198 new_unc->set_req(TypeFunc::Parms, unc->in(TypeFunc::Parms)); 1199 new_unc->set_req(0, c); 1200 new_unc = igvn->transform(new_unc); 1201 call_proj->set_req(0, new_unc); 1202 call_proj = igvn->transform(call_proj); 1203 halt->set_req(0, call_proj); 1204 halt = igvn->transform(halt); 1205 1206 igvn->replace_node(otherproj, igvn->C->top()); 1207 igvn->C->root()->add_req(halt); 1208 } 1209 1210 Node* IfNode::fold_compares(PhaseIterGVN* igvn) { 1211 if (Opcode() != Op_If) return NULL; 1212 1213 if (cmpi_folds(igvn)) { 1214 Node* ctrl = in(0); 1215 if (is_ctrl_folds(ctrl, igvn) && 1216 ctrl->outcnt() == 1) { 1217 // A integer comparison immediately dominated by another integer 1218 // comparison 1219 ProjNode* success = NULL; 1220 ProjNode* fail = NULL; 1221 ProjNode* dom_cmp = ctrl->as_Proj(); 1222 if (has_shared_region(dom_cmp, success, fail) && 1223 // Next call modifies graph so must be last 1224 fold_compares_helper(dom_cmp, success, fail, igvn)) { 1225 return this; 1226 } 1227 if (has_only_uncommon_traps(dom_cmp, success, fail, igvn) && 1228 // Next call modifies graph so must be last 1229 fold_compares_helper(dom_cmp, success, fail, igvn)) { 1230 merge_uncommon_traps(dom_cmp, success, fail, igvn); 1231 return this; 1232 } 1233 return NULL; 1234 } else if (ctrl->in(0) != NULL && 1235 ctrl->in(0)->in(0) != NULL) { 1236 ProjNode* success = NULL; 1237 ProjNode* fail = NULL; 1238 Node* dom = ctrl->in(0)->in(0); 1239 ProjNode* dom_cmp = dom->isa_Proj(); 1240 ProjNode* other_cmp = ctrl->isa_Proj(); 1241 1242 // Check if it's an integer comparison dominated by another 1243 // integer comparison with another test in between 1244 if (is_ctrl_folds(dom, igvn) && 1245 has_only_uncommon_traps(dom_cmp, success, fail, igvn) && 1246 is_side_effect_free_test(other_cmp, igvn) && 1247 // Next call modifies graph so must be last 1248 fold_compares_helper(dom_cmp, success, fail, igvn)) { 1249 reroute_side_effect_free_unc(other_cmp, dom_cmp, igvn); 1250 merge_uncommon_traps(dom_cmp, success, fail, igvn); 1251 return this; 1252 } 1253 } 1254 } 1255 return NULL; 1256 } 1257 1258 //------------------------------remove_useless_bool---------------------------- 1259 // Check for people making a useless boolean: things like 1260 // if( (x < y ? true : false) ) { ... } 1261 // Replace with if( x < y ) { ... } 1262 static Node *remove_useless_bool(IfNode *iff, PhaseGVN *phase) { 1263 Node *i1 = iff->in(1); 1264 if( !i1->is_Bool() ) return NULL; 1265 BoolNode *bol = i1->as_Bool(); 1266 1267 Node *cmp = bol->in(1); 1268 if( cmp->Opcode() != Op_CmpI ) return NULL; 1269 1270 // Must be comparing against a bool 1271 const Type *cmp2_t = phase->type( cmp->in(2) ); 1272 if( cmp2_t != TypeInt::ZERO && 1273 cmp2_t != TypeInt::ONE ) 1274 return NULL; 1275 1276 // Find a prior merge point merging the boolean 1277 i1 = cmp->in(1); 1278 if( !i1->is_Phi() ) return NULL; 1279 PhiNode *phi = i1->as_Phi(); 1280 if( phase->type( phi ) != TypeInt::BOOL ) 1281 return NULL; 1282 1283 // Check for diamond pattern 1284 int true_path = phi->is_diamond_phi(); 1285 if( true_path == 0 ) return NULL; 1286 1287 // Make sure that iff and the control of the phi are different. This 1288 // should really only happen for dead control flow since it requires 1289 // an illegal cycle. 1290 if (phi->in(0)->in(1)->in(0) == iff) return NULL; 1291 1292 // phi->region->if_proj->ifnode->bool->cmp 1293 BoolNode *bol2 = phi->in(0)->in(1)->in(0)->in(1)->as_Bool(); 1294 1295 // Now get the 'sense' of the test correct so we can plug in 1296 // either iff2->in(1) or its complement. 1297 int flip = 0; 1298 if( bol->_test._test == BoolTest::ne ) flip = 1-flip; 1299 else if( bol->_test._test != BoolTest::eq ) return NULL; 1300 if( cmp2_t == TypeInt::ZERO ) flip = 1-flip; 1301 1302 const Type *phi1_t = phase->type( phi->in(1) ); 1303 const Type *phi2_t = phase->type( phi->in(2) ); 1304 // Check for Phi(0,1) and flip 1305 if( phi1_t == TypeInt::ZERO ) { 1306 if( phi2_t != TypeInt::ONE ) return NULL; 1307 flip = 1-flip; 1308 } else { 1309 // Check for Phi(1,0) 1310 if( phi1_t != TypeInt::ONE ) return NULL; 1311 if( phi2_t != TypeInt::ZERO ) return NULL; 1312 } 1313 if( true_path == 2 ) { 1314 flip = 1-flip; 1315 } 1316 1317 Node* new_bol = (flip ? phase->transform( bol2->negate(phase) ) : bol2); 1318 assert(new_bol != iff->in(1), "must make progress"); 1319 iff->set_req(1, new_bol); 1320 // Intervening diamond probably goes dead 1321 phase->C->set_major_progress(); 1322 return iff; 1323 } 1324 1325 static IfNode* idealize_test(PhaseGVN* phase, IfNode* iff); 1326 1327 struct RangeCheck { 1328 Node* ctl; 1329 jint off; 1330 }; 1331 1332 //------------------------------Ideal------------------------------------------ 1333 // Return a node which is more "ideal" than the current node. Strip out 1334 // control copies 1335 Node *IfNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1336 if (remove_dead_region(phase, can_reshape)) return this; 1337 // No Def-Use info? 1338 if (!can_reshape) return NULL; 1339 PhaseIterGVN *igvn = phase->is_IterGVN(); 1340 1341 // Don't bother trying to transform a dead if 1342 if (in(0)->is_top()) return NULL; 1343 // Don't bother trying to transform an if with a dead test 1344 if (in(1)->is_top()) return NULL; 1345 // Another variation of a dead test 1346 if (in(1)->is_Con()) return NULL; 1347 // Another variation of a dead if 1348 if (outcnt() < 2) return NULL; 1349 1350 // Canonicalize the test. 1351 Node* idt_if = idealize_test(phase, this); 1352 if (idt_if != NULL) return idt_if; 1353 1354 // Try to split the IF 1355 Node *s = split_if(this, igvn); 1356 if (s != NULL) return s; 1357 1358 // Check for people making a useless boolean: things like 1359 // if( (x < y ? true : false) ) { ... } 1360 // Replace with if( x < y ) { ... } 1361 Node *bol2 = remove_useless_bool(this, phase); 1362 if( bol2 ) return bol2; 1363 1364 // Setup to scan up the CFG looking for a dominating test 1365 Node *dom = in(0); 1366 Node *prev_dom = this; 1367 1368 // Check for range-check vs other kinds of tests 1369 Node *index1, *range1; 1370 jint offset1; 1371 int flip1 = is_range_check(range1, index1, offset1); 1372 if( flip1 ) { 1373 // Try to remove extra range checks. All 'up_one_dom' gives up at merges 1374 // so all checks we inspect post-dominate the top-most check we find. 1375 // If we are going to fail the current check and we reach the top check 1376 // then we are guaranteed to fail, so just start interpreting there. 1377 // We 'expand' the top 3 range checks to include all post-dominating 1378 // checks. 1379 1380 // The top 3 range checks seen 1381 const int NRC =3; 1382 RangeCheck prev_checks[NRC]; 1383 int nb_checks = 0; 1384 1385 // Low and high offsets seen so far 1386 jint off_lo = offset1; 1387 jint off_hi = offset1; 1388 1389 bool found_immediate_dominator = false; 1390 1391 // Scan for the top checks and collect range of offsets 1392 for (int dist = 0; dist < 999; dist++) { // Range-Check scan limit 1393 if (dom->Opcode() == Op_If && // Not same opcode? 1394 prev_dom->in(0) == dom) { // One path of test does dominate? 1395 if (dom == this) return NULL; // dead loop 1396 // See if this is a range check 1397 Node *index2, *range2; 1398 jint offset2; 1399 int flip2 = dom->as_If()->is_range_check(range2, index2, offset2); 1400 // See if this is a _matching_ range check, checking against 1401 // the same array bounds. 1402 if (flip2 == flip1 && range2 == range1 && index2 == index1 && 1403 dom->outcnt() == 2) { 1404 if (nb_checks == 0 && dom->in(1) == in(1)) { 1405 // Found an immediately dominating test at the same offset. 1406 // This kind of back-to-back test can be eliminated locally, 1407 // and there is no need to search further for dominating tests. 1408 assert(offset2 == offset1, "Same test but different offsets"); 1409 found_immediate_dominator = true; 1410 break; 1411 } 1412 // Gather expanded bounds 1413 off_lo = MIN2(off_lo,offset2); 1414 off_hi = MAX2(off_hi,offset2); 1415 // Record top NRC range checks 1416 prev_checks[nb_checks%NRC].ctl = prev_dom; 1417 prev_checks[nb_checks%NRC].off = offset2; 1418 nb_checks++; 1419 } 1420 } 1421 prev_dom = dom; 1422 dom = up_one_dom(dom); 1423 if (!dom) break; 1424 } 1425 1426 if (!found_immediate_dominator) { 1427 // Attempt to widen the dominating range check to cover some later 1428 // ones. Since range checks "fail" by uncommon-trapping to the 1429 // interpreter, widening a check can make us speculatively enter 1430 // the interpreter. If we see range-check deopt's, do not widen! 1431 if (!phase->C->allow_range_check_smearing()) return NULL; 1432 1433 // Didn't find prior covering check, so cannot remove anything. 1434 if (nb_checks == 0) { 1435 return NULL; 1436 } 1437 // Constant indices only need to check the upper bound. 1438 // Non-constant indices must check both low and high. 1439 int chk0 = (nb_checks - 1) % NRC; 1440 if (index1) { 1441 if (nb_checks == 1) { 1442 return NULL; 1443 } else { 1444 // If the top range check's constant is the min or max of 1445 // all constants we widen the next one to cover the whole 1446 // range of constants. 1447 RangeCheck rc0 = prev_checks[chk0]; 1448 int chk1 = (nb_checks - 2) % NRC; 1449 RangeCheck rc1 = prev_checks[chk1]; 1450 if (rc0.off == off_lo) { 1451 adjust_check(rc1.ctl, range1, index1, flip1, off_hi, igvn); 1452 prev_dom = rc1.ctl; 1453 } else if (rc0.off == off_hi) { 1454 adjust_check(rc1.ctl, range1, index1, flip1, off_lo, igvn); 1455 prev_dom = rc1.ctl; 1456 } else { 1457 // If the top test's constant is not the min or max of all 1458 // constants, we need 3 range checks. We must leave the 1459 // top test unchanged because widening it would allow the 1460 // accesses it protects to successfully read/write out of 1461 // bounds. 1462 if (nb_checks == 2) { 1463 return NULL; 1464 } 1465 int chk2 = (nb_checks - 3) % NRC; 1466 RangeCheck rc2 = prev_checks[chk2]; 1467 // The top range check a+i covers interval: -a <= i < length-a 1468 // The second range check b+i covers interval: -b <= i < length-b 1469 if (rc1.off <= rc0.off) { 1470 // if b <= a, we change the second range check to: 1471 // -min_of_all_constants <= i < length-min_of_all_constants 1472 // Together top and second range checks now cover: 1473 // -min_of_all_constants <= i < length-a 1474 // which is more restrictive than -b <= i < length-b: 1475 // -b <= -min_of_all_constants <= i < length-a <= length-b 1476 // The third check is then changed to: 1477 // -max_of_all_constants <= i < length-max_of_all_constants 1478 // so 2nd and 3rd checks restrict allowed values of i to: 1479 // -min_of_all_constants <= i < length-max_of_all_constants 1480 adjust_check(rc1.ctl, range1, index1, flip1, off_lo, igvn); 1481 adjust_check(rc2.ctl, range1, index1, flip1, off_hi, igvn); 1482 } else { 1483 // if b > a, we change the second range check to: 1484 // -max_of_all_constants <= i < length-max_of_all_constants 1485 // Together top and second range checks now cover: 1486 // -a <= i < length-max_of_all_constants 1487 // which is more restrictive than -b <= i < length-b: 1488 // -b < -a <= i < length-max_of_all_constants <= length-b 1489 // The third check is then changed to: 1490 // -max_of_all_constants <= i < length-max_of_all_constants 1491 // so 2nd and 3rd checks restrict allowed values of i to: 1492 // -min_of_all_constants <= i < length-max_of_all_constants 1493 adjust_check(rc1.ctl, range1, index1, flip1, off_hi, igvn); 1494 adjust_check(rc2.ctl, range1, index1, flip1, off_lo, igvn); 1495 } 1496 prev_dom = rc2.ctl; 1497 } 1498 } 1499 } else { 1500 RangeCheck rc0 = prev_checks[chk0]; 1501 // 'Widen' the offset of the 1st and only covering check 1502 adjust_check(rc0.ctl, range1, index1, flip1, off_hi, igvn); 1503 // Test is now covered by prior checks, dominate it out 1504 prev_dom = rc0.ctl; 1505 } 1506 } 1507 1508 } else { // Scan for an equivalent test 1509 1510 Node *cmp; 1511 int dist = 0; // Cutoff limit for search 1512 int op = Opcode(); 1513 if( op == Op_If && 1514 (cmp=in(1)->in(1))->Opcode() == Op_CmpP ) { 1515 if( cmp->in(2) != NULL && // make sure cmp is not already dead 1516 cmp->in(2)->bottom_type() == TypePtr::NULL_PTR ) { 1517 dist = 64; // Limit for null-pointer scans 1518 } else { 1519 dist = 4; // Do not bother for random pointer tests 1520 } 1521 } else { 1522 dist = 4; // Limit for random junky scans 1523 } 1524 1525 // Normal equivalent-test check. 1526 if( !dom ) return NULL; // Dead loop? 1527 1528 Node* result = fold_compares(igvn); 1529 if (result != NULL) { 1530 return result; 1531 } 1532 1533 // Search up the dominator tree for an If with an identical test 1534 while( dom->Opcode() != op || // Not same opcode? 1535 dom->in(1) != in(1) || // Not same input 1? 1536 (req() == 3 && dom->in(2) != in(2)) || // Not same input 2? 1537 prev_dom->in(0) != dom ) { // One path of test does not dominate? 1538 if( dist < 0 ) return NULL; 1539 1540 dist--; 1541 prev_dom = dom; 1542 dom = up_one_dom( dom ); 1543 if( !dom ) return NULL; 1544 } 1545 1546 // Check that we did not follow a loop back to ourselves 1547 if( this == dom ) 1548 return NULL; 1549 1550 if( dist > 2 ) // Add to count of NULL checks elided 1551 explicit_null_checks_elided++; 1552 1553 } // End of Else scan for an equivalent test 1554 1555 // Hit! Remove this IF 1556 #ifndef PRODUCT 1557 if( TraceIterativeGVN ) { 1558 tty->print(" Removing IfNode: "); this->dump(); 1559 } 1560 if( VerifyOpto && !phase->allow_progress() ) { 1561 // Found an equivalent dominating test, 1562 // we can not guarantee reaching a fix-point for these during iterativeGVN 1563 // since intervening nodes may not change. 1564 return NULL; 1565 } 1566 #endif 1567 1568 // Replace dominated IfNode 1569 dominated_by( prev_dom, igvn ); 1570 1571 // Must return either the original node (now dead) or a new node 1572 // (Do not return a top here, since that would break the uniqueness of top.) 1573 return new ConINode(TypeInt::ZERO); 1574 } 1575 1576 //------------------------------dominated_by----------------------------------- 1577 void IfNode::dominated_by( Node *prev_dom, PhaseIterGVN *igvn ) { 1578 igvn->hash_delete(this); // Remove self to prevent spurious V-N 1579 Node *idom = in(0); 1580 // Need opcode to decide which way 'this' test goes 1581 int prev_op = prev_dom->Opcode(); 1582 Node *top = igvn->C->top(); // Shortcut to top 1583 1584 // Loop predicates may have depending checks which should not 1585 // be skipped. For example, range check predicate has two checks 1586 // for lower and upper bounds. 1587 ProjNode* unc_proj = proj_out(1 - prev_dom->as_Proj()->_con)->as_Proj(); 1588 if (unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_predicate) != NULL) 1589 prev_dom = idom; 1590 1591 // Now walk the current IfNode's projections. 1592 // Loop ends when 'this' has no more uses. 1593 for (DUIterator_Last imin, i = last_outs(imin); i >= imin; --i) { 1594 Node *ifp = last_out(i); // Get IfTrue/IfFalse 1595 igvn->add_users_to_worklist(ifp); 1596 // Check which projection it is and set target. 1597 // Data-target is either the dominating projection of the same type 1598 // or TOP if the dominating projection is of opposite type. 1599 // Data-target will be used as the new control edge for the non-CFG 1600 // nodes like Casts and Loads. 1601 Node *data_target = (ifp->Opcode() == prev_op) ? prev_dom : top; 1602 // Control-target is just the If's immediate dominator or TOP. 1603 Node *ctrl_target = (ifp->Opcode() == prev_op) ? idom : top; 1604 1605 // For each child of an IfTrue/IfFalse projection, reroute. 1606 // Loop ends when projection has no more uses. 1607 for (DUIterator_Last jmin, j = ifp->last_outs(jmin); j >= jmin; --j) { 1608 Node* s = ifp->last_out(j); // Get child of IfTrue/IfFalse 1609 if( !s->depends_only_on_test() ) { 1610 // Find the control input matching this def-use edge. 1611 // For Regions it may not be in slot 0. 1612 uint l; 1613 for( l = 0; s->in(l) != ifp; l++ ) { } 1614 igvn->replace_input_of(s, l, ctrl_target); 1615 } else { // Else, for control producers, 1616 igvn->replace_input_of(s, 0, data_target); // Move child to data-target 1617 } 1618 } // End for each child of a projection 1619 1620 igvn->remove_dead_node(ifp); 1621 } // End for each IfTrue/IfFalse child of If 1622 1623 // Kill the IfNode 1624 igvn->remove_dead_node(this); 1625 } 1626 1627 //------------------------------Identity--------------------------------------- 1628 // If the test is constant & we match, then we are the input Control 1629 Node *IfProjNode::Identity(PhaseTransform *phase) { 1630 // Can only optimize if cannot go the other way 1631 const TypeTuple *t = phase->type(in(0))->is_tuple(); 1632 if (t == TypeTuple::IFNEITHER || 1633 // kill dead branch first otherwise the IfNode's control will 1634 // have 2 control uses (the IfNode that doesn't go away because 1635 // it still has uses and this branch of the 1636 // If). Node::has_special_unique_user() will cause this node to 1637 // be reprocessed once the dead branch is killed. 1638 (always_taken(t) && in(0)->outcnt() == 1)) { 1639 // IfNode control 1640 return in(0)->in(0); 1641 } 1642 // no progress 1643 return this; 1644 } 1645 1646 #ifndef PRODUCT 1647 //-------------------------------related--------------------------------------- 1648 // An IfProjNode's related node set consists of its input (an IfNode) including 1649 // the IfNode's condition, plus all of its outputs at level 1. In compact mode, 1650 // the restrictions for IfNode apply (see IfNode::rel). 1651 void IfProjNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const { 1652 Node* ifNode = this->in(0); 1653 in_rel->append(ifNode); 1654 if (compact) { 1655 ifNode->collect_nodes(in_rel, 3, false, true); 1656 } else { 1657 ifNode->collect_nodes_in_all_data(in_rel, false); 1658 } 1659 this->collect_nodes(out_rel, -1, false, false); 1660 } 1661 1662 //------------------------------dump_spec-------------------------------------- 1663 void IfNode::dump_spec(outputStream *st) const { 1664 st->print("P=%f, C=%f",_prob,_fcnt); 1665 } 1666 1667 //-------------------------------related--------------------------------------- 1668 // For an IfNode, the set of related output nodes is just the output nodes till 1669 // depth 2, i.e, the IfTrue/IfFalse projection nodes plus the nodes they refer. 1670 // The related input nodes contain no control nodes, but all data nodes 1671 // pertaining to the condition. In compact mode, the input nodes are collected 1672 // up to a depth of 3. 1673 void IfNode::related(GrowableArray <Node *> *in_rel, GrowableArray <Node *> *out_rel, bool compact) const { 1674 if (compact) { 1675 this->collect_nodes(in_rel, 3, false, true); 1676 } else { 1677 this->collect_nodes_in_all_data(in_rel, false); 1678 } 1679 this->collect_nodes(out_rel, -2, false, false); 1680 } 1681 #endif 1682 1683 //------------------------------idealize_test---------------------------------- 1684 // Try to canonicalize tests better. Peek at the Cmp/Bool/If sequence and 1685 // come up with a canonical sequence. Bools getting 'eq', 'gt' and 'ge' forms 1686 // converted to 'ne', 'le' and 'lt' forms. IfTrue/IfFalse get swapped as 1687 // needed. 1688 static IfNode* idealize_test(PhaseGVN* phase, IfNode* iff) { 1689 assert(iff->in(0) != NULL, "If must be live"); 1690 1691 if (iff->outcnt() != 2) return NULL; // Malformed projections. 1692 Node* old_if_f = iff->proj_out(false); 1693 Node* old_if_t = iff->proj_out(true); 1694 1695 // CountedLoopEnds want the back-control test to be TRUE, irregardless of 1696 // whether they are testing a 'gt' or 'lt' condition. The 'gt' condition 1697 // happens in count-down loops 1698 if (iff->is_CountedLoopEnd()) return NULL; 1699 if (!iff->in(1)->is_Bool()) return NULL; // Happens for partially optimized IF tests 1700 BoolNode *b = iff->in(1)->as_Bool(); 1701 BoolTest bt = b->_test; 1702 // Test already in good order? 1703 if( bt.is_canonical() ) 1704 return NULL; 1705 1706 // Flip test to be canonical. Requires flipping the IfFalse/IfTrue and 1707 // cloning the IfNode. 1708 Node* new_b = phase->transform( new BoolNode(b->in(1), bt.negate()) ); 1709 if( !new_b->is_Bool() ) return NULL; 1710 b = new_b->as_Bool(); 1711 1712 PhaseIterGVN *igvn = phase->is_IterGVN(); 1713 assert( igvn, "Test is not canonical in parser?" ); 1714 1715 // The IF node never really changes, but it needs to be cloned 1716 iff = new IfNode( iff->in(0), b, 1.0-iff->_prob, iff->_fcnt); 1717 1718 Node *prior = igvn->hash_find_insert(iff); 1719 if( prior ) { 1720 igvn->remove_dead_node(iff); 1721 iff = (IfNode*)prior; 1722 } else { 1723 // Cannot call transform on it just yet 1724 igvn->set_type_bottom(iff); 1725 } 1726 igvn->_worklist.push(iff); 1727 1728 // Now handle projections. Cloning not required. 1729 Node* new_if_f = (Node*)(new IfFalseNode( iff )); 1730 Node* new_if_t = (Node*)(new IfTrueNode ( iff )); 1731 1732 igvn->register_new_node_with_optimizer(new_if_f); 1733 igvn->register_new_node_with_optimizer(new_if_t); 1734 // Flip test, so flip trailing control 1735 igvn->replace_node(old_if_f, new_if_t); 1736 igvn->replace_node(old_if_t, new_if_f); 1737 1738 // Progress 1739 return iff; 1740 }