1 /* 2 * Copyright (c) 2000, 2013, 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 "memory/allocation.inline.hpp" 27 #include "opto/addnode.hpp" 28 #include "opto/cfgnode.hpp" 29 #include "opto/connode.hpp" 30 #include "opto/loopnode.hpp" 31 #include "opto/phaseX.hpp" 32 #include "opto/runtime.hpp" 33 #include "opto/subnode.hpp" 34 35 // Portions of code courtesy of Clifford Click 36 37 // Optimization - Graph Style 38 39 40 extern int explicit_null_checks_elided; 41 42 //============================================================================= 43 //------------------------------Value------------------------------------------ 44 // Return a tuple for whichever arm of the IF is reachable 45 const Type *IfNode::Value( PhaseTransform *phase ) const { 46 if( !in(0) ) return Type::TOP; 47 if( phase->type(in(0)) == Type::TOP ) 48 return Type::TOP; 49 const Type *t = phase->type(in(1)); 50 if( t == Type::TOP ) // data is undefined 51 return TypeTuple::IFNEITHER; // unreachable altogether 52 if( t == TypeInt::ZERO ) // zero, or false 53 return TypeTuple::IFFALSE; // only false branch is reachable 54 if( t == TypeInt::ONE ) // 1, or true 55 return TypeTuple::IFTRUE; // only true branch is reachable 56 assert( t == TypeInt::BOOL, "expected boolean type" ); 57 58 return TypeTuple::IFBOTH; // No progress 59 } 60 61 const RegMask &IfNode::out_RegMask() const { 62 return RegMask::Empty; 63 } 64 65 //------------------------------split_if--------------------------------------- 66 // Look for places where we merge constants, then test on the merged value. 67 // If the IF test will be constant folded on the path with the constant, we 68 // win by splitting the IF to before the merge point. 69 static Node* split_if(IfNode *iff, PhaseIterGVN *igvn) { 70 // I could be a lot more general here, but I'm trying to squeeze this 71 // in before the Christmas '98 break so I'm gonna be kinda restrictive 72 // on the patterns I accept. CNC 73 74 // Look for a compare of a constant and a merged value 75 Node *i1 = iff->in(1); 76 if( !i1->is_Bool() ) return NULL; 77 BoolNode *b = i1->as_Bool(); 78 Node *cmp = b->in(1); 79 if( !cmp->is_Cmp() ) return NULL; 80 i1 = cmp->in(1); 81 if( i1 == NULL || !i1->is_Phi() ) return NULL; 82 PhiNode *phi = i1->as_Phi(); 83 if( phi->is_copy() ) return NULL; 84 Node *con2 = cmp->in(2); 85 if( !con2->is_Con() ) return NULL; 86 // See that the merge point contains some constants 87 Node *con1=NULL; 88 uint i4; 89 for( i4 = 1; i4 < phi->req(); i4++ ) { 90 con1 = phi->in(i4); 91 if( !con1 ) return NULL; // Do not optimize partially collapsed merges 92 if( con1->is_Con() ) break; // Found a constant 93 // Also allow null-vs-not-null checks 94 const TypePtr *tp = igvn->type(con1)->isa_ptr(); 95 if( tp && tp->_ptr == TypePtr::NotNull ) 96 break; 97 } 98 if( i4 >= phi->req() ) return NULL; // Found no constants 99 100 igvn->C->set_has_split_ifs(true); // Has chance for split-if 101 102 // Make sure that the compare can be constant folded away 103 Node *cmp2 = cmp->clone(); 104 cmp2->set_req(1,con1); 105 cmp2->set_req(2,con2); 106 const Type *t = cmp2->Value(igvn); 107 // This compare is dead, so whack it! 108 igvn->remove_dead_node(cmp2); 109 if( !t->singleton() ) return NULL; 110 111 // No intervening control, like a simple Call 112 Node *r = iff->in(0); 113 if( !r->is_Region() ) return NULL; 114 if( phi->region() != r ) return NULL; 115 // No other users of the cmp/bool 116 if (b->outcnt() != 1 || cmp->outcnt() != 1) { 117 //tty->print_cr("many users of cmp/bool"); 118 return NULL; 119 } 120 121 // Make sure we can determine where all the uses of merged values go 122 for (DUIterator_Fast jmax, j = r->fast_outs(jmax); j < jmax; j++) { 123 Node* u = r->fast_out(j); 124 if( u == r ) continue; 125 if( u == iff ) continue; 126 if( u->outcnt() == 0 ) continue; // use is dead & ignorable 127 if( !u->is_Phi() ) { 128 /* 129 if( u->is_Start() ) { 130 tty->print_cr("Region has inlined start use"); 131 } else { 132 tty->print_cr("Region has odd use"); 133 u->dump(2); 134 }*/ 135 return NULL; 136 } 137 if( u != phi ) { 138 // CNC - do not allow any other merged value 139 //tty->print_cr("Merging another value"); 140 //u->dump(2); 141 return NULL; 142 } 143 // Make sure we can account for all Phi uses 144 for (DUIterator_Fast kmax, k = u->fast_outs(kmax); k < kmax; k++) { 145 Node* v = u->fast_out(k); // User of the phi 146 // CNC - Allow only really simple patterns. 147 // In particular I disallow AddP of the Phi, a fairly common pattern 148 if (v == cmp) continue; // The compare is OK 149 if (v->is_ConstraintCast()) { 150 // If the cast is derived from data flow edges, it may not have a control edge. 151 // If so, it should be safe to split. But follow-up code can not deal with 152 // this (l. 359). So skip. 153 if (v->in(0) == NULL) { 154 return NULL; 155 } 156 if (v->in(0)->in(0) == iff) { 157 continue; // CastPP/II of the IfNode is OK 158 } 159 } 160 // Disabled following code because I cannot tell if exactly one 161 // path dominates without a real dominator check. CNC 9/9/1999 162 //uint vop = v->Opcode(); 163 //if( vop == Op_Phi ) { // Phi from another merge point might be OK 164 // Node *r = v->in(0); // Get controlling point 165 // if( !r ) return NULL; // Degraded to a copy 166 // // Find exactly one path in (either True or False doms, but not IFF) 167 // int cnt = 0; 168 // for( uint i = 1; i < r->req(); i++ ) 169 // if( r->in(i) && r->in(i)->in(0) == iff ) 170 // cnt++; 171 // if( cnt == 1 ) continue; // Exactly one of True or False guards Phi 172 //} 173 if( !v->is_Call() ) { 174 /* 175 if( v->Opcode() == Op_AddP ) { 176 tty->print_cr("Phi has AddP use"); 177 } else if( v->Opcode() == Op_CastPP ) { 178 tty->print_cr("Phi has CastPP use"); 179 } else if( v->Opcode() == Op_CastII ) { 180 tty->print_cr("Phi has CastII use"); 181 } else { 182 tty->print_cr("Phi has use I cant be bothered with"); 183 } 184 */ 185 } 186 return NULL; 187 188 /* CNC - Cut out all the fancy acceptance tests 189 // Can we clone this use when doing the transformation? 190 // If all uses are from Phis at this merge or constants, then YES. 191 if( !v->in(0) && v != cmp ) { 192 tty->print_cr("Phi has free-floating use"); 193 v->dump(2); 194 return NULL; 195 } 196 for( uint l = 1; l < v->req(); l++ ) { 197 if( (!v->in(l)->is_Phi() || v->in(l)->in(0) != r) && 198 !v->in(l)->is_Con() ) { 199 tty->print_cr("Phi has use"); 200 v->dump(2); 201 return NULL; 202 } // End of if Phi-use input is neither Phi nor Constant 203 } // End of for all inputs to Phi-use 204 */ 205 } // End of for all uses of Phi 206 } // End of for all uses of Region 207 208 // Only do this if the IF node is in a sane state 209 if (iff->outcnt() != 2) 210 return NULL; 211 212 // Got a hit! Do the Mondo Hack! 213 // 214 //ABC a1c def ghi B 1 e h A C a c d f g i 215 // R - Phi - Phi - Phi Rc - Phi - Phi - Phi Rx - Phi - Phi - Phi 216 // cmp - 2 cmp - 2 cmp - 2 217 // bool bool_c bool_x 218 // if if_c if_x 219 // T F T F T F 220 // ..s.. ..t .. ..s.. ..t.. ..s.. ..t.. 221 // 222 // Split the paths coming into the merge point into 2 separate groups of 223 // merges. On the left will be all the paths feeding constants into the 224 // Cmp's Phi. On the right will be the remaining paths. The Cmp's Phi 225 // will fold up into a constant; this will let the Cmp fold up as well as 226 // all the control flow. Below the original IF we have 2 control 227 // dependent regions, 's' and 't'. Now we will merge the two paths 228 // just prior to 's' and 't' from the two IFs. At least 1 path (and quite 229 // likely 2 or more) will promptly constant fold away. 230 PhaseGVN *phase = igvn; 231 232 // Make a region merging constants and a region merging the rest 233 uint req_c = 0; 234 Node* predicate_proj = NULL; 235 for (uint ii = 1; ii < r->req(); ii++) { 236 if (phi->in(ii) == con1) { 237 req_c++; 238 } 239 Node* proj = PhaseIdealLoop::find_predicate(r->in(ii)); 240 if (proj != NULL) { 241 assert(predicate_proj == NULL, "only one predicate entry expected"); 242 predicate_proj = proj; 243 } 244 } 245 Node* predicate_c = NULL; 246 Node* predicate_x = NULL; 247 bool counted_loop = r->is_CountedLoop(); 248 249 Node *region_c = new RegionNode(req_c + 1); 250 Node *phi_c = con1; 251 uint len = r->req(); 252 Node *region_x = new RegionNode(len - req_c); 253 Node *phi_x = PhiNode::make_blank(region_x, phi); 254 for (uint i = 1, i_c = 1, i_x = 1; i < len; i++) { 255 if (phi->in(i) == con1) { 256 region_c->init_req( i_c++, r ->in(i) ); 257 if (r->in(i) == predicate_proj) 258 predicate_c = predicate_proj; 259 } else { 260 region_x->init_req( i_x, r ->in(i) ); 261 phi_x ->init_req( i_x++, phi->in(i) ); 262 if (r->in(i) == predicate_proj) 263 predicate_x = predicate_proj; 264 } 265 } 266 if (predicate_c != NULL && (req_c > 1)) { 267 assert(predicate_x == NULL, "only one predicate entry expected"); 268 predicate_c = NULL; // Do not clone predicate below merge point 269 } 270 if (predicate_x != NULL && ((len - req_c) > 2)) { 271 assert(predicate_c == NULL, "only one predicate entry expected"); 272 predicate_x = NULL; // Do not clone predicate below merge point 273 } 274 275 // Register the new RegionNodes but do not transform them. Cannot 276 // transform until the entire Region/Phi conglomerate has been hacked 277 // as a single huge transform. 278 igvn->register_new_node_with_optimizer( region_c ); 279 igvn->register_new_node_with_optimizer( region_x ); 280 // Prevent the untimely death of phi_x. Currently he has no uses. He is 281 // about to get one. If this only use goes away, then phi_x will look dead. 282 // However, he will be picking up some more uses down below. 283 Node *hook = new Node(4); 284 hook->init_req(0, phi_x); 285 hook->init_req(1, phi_c); 286 phi_x = phase->transform( phi_x ); 287 288 // Make the compare 289 Node *cmp_c = phase->makecon(t); 290 Node *cmp_x = cmp->clone(); 291 cmp_x->set_req(1,phi_x); 292 cmp_x->set_req(2,con2); 293 cmp_x = phase->transform(cmp_x); 294 // Make the bool 295 Node *b_c = phase->transform(new BoolNode(cmp_c,b->_test._test)); 296 Node *b_x = phase->transform(new BoolNode(cmp_x,b->_test._test)); 297 // Make the IfNode 298 IfNode *iff_c = new IfNode(region_c,b_c,iff->_prob,iff->_fcnt); 299 igvn->set_type_bottom(iff_c); 300 igvn->_worklist.push(iff_c); 301 hook->init_req(2, iff_c); 302 303 IfNode *iff_x = new IfNode(region_x,b_x,iff->_prob, iff->_fcnt); 304 igvn->set_type_bottom(iff_x); 305 igvn->_worklist.push(iff_x); 306 hook->init_req(3, iff_x); 307 308 // Make the true/false arms 309 Node *iff_c_t = phase->transform(new IfTrueNode (iff_c)); 310 Node *iff_c_f = phase->transform(new IfFalseNode(iff_c)); 311 if (predicate_c != NULL) { 312 assert(predicate_x == NULL, "only one predicate entry expected"); 313 // Clone loop predicates to each path 314 iff_c_t = igvn->clone_loop_predicates(predicate_c, iff_c_t, !counted_loop); 315 iff_c_f = igvn->clone_loop_predicates(predicate_c, iff_c_f, !counted_loop); 316 } 317 Node *iff_x_t = phase->transform(new IfTrueNode (iff_x)); 318 Node *iff_x_f = phase->transform(new IfFalseNode(iff_x)); 319 if (predicate_x != NULL) { 320 assert(predicate_c == NULL, "only one predicate entry expected"); 321 // Clone loop predicates to each path 322 iff_x_t = igvn->clone_loop_predicates(predicate_x, iff_x_t, !counted_loop); 323 iff_x_f = igvn->clone_loop_predicates(predicate_x, iff_x_f, !counted_loop); 324 } 325 326 // Merge the TRUE paths 327 Node *region_s = new RegionNode(3); 328 igvn->_worklist.push(region_s); 329 region_s->init_req(1, iff_c_t); 330 region_s->init_req(2, iff_x_t); 331 igvn->register_new_node_with_optimizer( region_s ); 332 333 // Merge the FALSE paths 334 Node *region_f = new RegionNode(3); 335 igvn->_worklist.push(region_f); 336 region_f->init_req(1, iff_c_f); 337 region_f->init_req(2, iff_x_f); 338 igvn->register_new_node_with_optimizer( region_f ); 339 340 igvn->hash_delete(cmp);// Remove soon-to-be-dead node from hash table. 341 cmp->set_req(1,NULL); // Whack the inputs to cmp because it will be dead 342 cmp->set_req(2,NULL); 343 // Check for all uses of the Phi and give them a new home. 344 // The 'cmp' got cloned, but CastPP/IIs need to be moved. 345 Node *phi_s = NULL; // do not construct unless needed 346 Node *phi_f = NULL; // do not construct unless needed 347 for (DUIterator_Last i2min, i2 = phi->last_outs(i2min); i2 >= i2min; --i2) { 348 Node* v = phi->last_out(i2);// User of the phi 349 igvn->rehash_node_delayed(v); // Have to fixup other Phi users 350 uint vop = v->Opcode(); 351 Node *proj = NULL; 352 if( vop == Op_Phi ) { // Remote merge point 353 Node *r = v->in(0); 354 for (uint i3 = 1; i3 < r->req(); i3++) 355 if (r->in(i3) && r->in(i3)->in(0) == iff) { 356 proj = r->in(i3); 357 break; 358 } 359 } else if( v->is_ConstraintCast() ) { 360 proj = v->in(0); // Controlling projection 361 } else { 362 assert( 0, "do not know how to handle this guy" ); 363 } 364 365 Node *proj_path_data, *proj_path_ctrl; 366 if( proj->Opcode() == Op_IfTrue ) { 367 if( phi_s == NULL ) { 368 // Only construct phi_s if needed, otherwise provides 369 // interfering use. 370 phi_s = PhiNode::make_blank(region_s,phi); 371 phi_s->init_req( 1, phi_c ); 372 phi_s->init_req( 2, phi_x ); 373 hook->add_req(phi_s); 374 phi_s = phase->transform(phi_s); 375 } 376 proj_path_data = phi_s; 377 proj_path_ctrl = region_s; 378 } else { 379 if( phi_f == NULL ) { 380 // Only construct phi_f if needed, otherwise provides 381 // interfering use. 382 phi_f = PhiNode::make_blank(region_f,phi); 383 phi_f->init_req( 1, phi_c ); 384 phi_f->init_req( 2, phi_x ); 385 hook->add_req(phi_f); 386 phi_f = phase->transform(phi_f); 387 } 388 proj_path_data = phi_f; 389 proj_path_ctrl = region_f; 390 } 391 392 // Fixup 'v' for for the split 393 if( vop == Op_Phi ) { // Remote merge point 394 uint i; 395 for( i = 1; i < v->req(); i++ ) 396 if( v->in(i) == phi ) 397 break; 398 v->set_req(i, proj_path_data ); 399 } else if( v->is_ConstraintCast() ) { 400 v->set_req(0, proj_path_ctrl ); 401 v->set_req(1, proj_path_data ); 402 } else 403 ShouldNotReachHere(); 404 } 405 406 // Now replace the original iff's True/False with region_s/region_t. 407 // This makes the original iff go dead. 408 for (DUIterator_Last i3min, i3 = iff->last_outs(i3min); i3 >= i3min; --i3) { 409 Node* p = iff->last_out(i3); 410 assert( p->Opcode() == Op_IfTrue || p->Opcode() == Op_IfFalse, "" ); 411 Node *u = (p->Opcode() == Op_IfTrue) ? region_s : region_f; 412 // Replace p with u 413 igvn->add_users_to_worklist(p); 414 for (DUIterator_Last lmin, l = p->last_outs(lmin); l >= lmin;) { 415 Node* x = p->last_out(l); 416 igvn->hash_delete(x); 417 uint uses_found = 0; 418 for( uint j = 0; j < x->req(); j++ ) { 419 if( x->in(j) == p ) { 420 x->set_req(j, u); 421 uses_found++; 422 } 423 } 424 l -= uses_found; // we deleted 1 or more copies of this edge 425 } 426 igvn->remove_dead_node(p); 427 } 428 429 // Force the original merge dead 430 igvn->hash_delete(r); 431 // First, remove region's dead users. 432 for (DUIterator_Last lmin, l = r->last_outs(lmin); l >= lmin;) { 433 Node* u = r->last_out(l); 434 if( u == r ) { 435 r->set_req(0, NULL); 436 } else { 437 assert(u->outcnt() == 0, "only dead users"); 438 igvn->remove_dead_node(u); 439 } 440 l -= 1; 441 } 442 igvn->remove_dead_node(r); 443 444 // Now remove the bogus extra edges used to keep things alive 445 igvn->remove_dead_node( hook ); 446 447 // Must return either the original node (now dead) or a new node 448 // (Do not return a top here, since that would break the uniqueness of top.) 449 return new ConINode(TypeInt::ZERO); 450 } 451 452 //------------------------------is_range_check--------------------------------- 453 // Return 0 if not a range check. Return 1 if a range check and set index and 454 // offset. Return 2 if we had to negate the test. Index is NULL if the check 455 // is versus a constant. 456 int IfNode::is_range_check(Node* &range, Node* &index, jint &offset) { 457 Node* b = in(1); 458 if (b == NULL || !b->is_Bool()) return 0; 459 BoolNode* bn = b->as_Bool(); 460 Node* cmp = bn->in(1); 461 if (cmp == NULL) return 0; 462 if (cmp->Opcode() != Op_CmpU) return 0; 463 464 Node* l = cmp->in(1); 465 Node* r = cmp->in(2); 466 int flip_test = 1; 467 if (bn->_test._test == BoolTest::le) { 468 l = cmp->in(2); 469 r = cmp->in(1); 470 flip_test = 2; 471 } else if (bn->_test._test != BoolTest::lt) { 472 return 0; 473 } 474 if (l->is_top()) return 0; // Top input means dead test 475 if (r->Opcode() != Op_LoadRange) return 0; 476 477 // We have recognized one of these forms: 478 // Flip 1: If (Bool[<] CmpU(l, LoadRange)) ... 479 // Flip 2: If (Bool[<=] CmpU(LoadRange, l)) ... 480 481 // Make sure it's a real range check by requiring an uncommon trap 482 // along the OOB path. Otherwise, it's possible that the user wrote 483 // something which optimized to look like a range check but behaves 484 // in some other way. 485 Node* iftrap = proj_out(flip_test == 2 ? true : false); 486 bool found_trap = false; 487 if (iftrap != NULL) { 488 Node* u = iftrap->unique_ctrl_out(); 489 if (u != NULL) { 490 // It could be a merge point (Region) for uncommon trap. 491 if (u->is_Region()) { 492 Node* c = u->unique_ctrl_out(); 493 if (c != NULL) { 494 iftrap = u; 495 u = c; 496 } 497 } 498 if (u->in(0) == iftrap && u->is_CallStaticJava()) { 499 int req = u->as_CallStaticJava()->uncommon_trap_request(); 500 if (Deoptimization::trap_request_reason(req) == 501 Deoptimization::Reason_range_check) { 502 found_trap = true; 503 } 504 } 505 } 506 } 507 if (!found_trap) return 0; // sorry, no cigar 508 509 // Look for index+offset form 510 Node* ind = l; 511 jint off = 0; 512 if (l->is_top()) { 513 return 0; 514 } else if (l->Opcode() == Op_AddI) { 515 if ((off = l->in(1)->find_int_con(0)) != 0) { 516 ind = l->in(2); 517 } else if ((off = l->in(2)->find_int_con(0)) != 0) { 518 ind = l->in(1); 519 } 520 } else if ((off = l->find_int_con(-1)) >= 0) { 521 // constant offset with no variable index 522 ind = NULL; 523 } else { 524 // variable index with no constant offset (or dead negative index) 525 off = 0; 526 } 527 528 // Return all the values: 529 index = ind; 530 offset = off; 531 range = r; 532 return flip_test; 533 } 534 535 //------------------------------adjust_check----------------------------------- 536 // Adjust (widen) a prior range check 537 static void adjust_check(Node* proj, Node* range, Node* index, 538 int flip, jint off_lo, PhaseIterGVN* igvn) { 539 PhaseGVN *gvn = igvn; 540 // Break apart the old check 541 Node *iff = proj->in(0); 542 Node *bol = iff->in(1); 543 if( bol->is_top() ) return; // In case a partially dead range check appears 544 // bail (or bomb[ASSERT/DEBUG]) if NOT projection-->IfNode-->BoolNode 545 DEBUG_ONLY( if( !bol->is_Bool() ) { proj->dump(3); fatal("Expect projection-->IfNode-->BoolNode"); } ) 546 if( !bol->is_Bool() ) return; 547 548 Node *cmp = bol->in(1); 549 // Compute a new check 550 Node *new_add = gvn->intcon(off_lo); 551 if( index ) { 552 new_add = off_lo ? gvn->transform(new AddINode( index, new_add )) : index; 553 } 554 Node *new_cmp = (flip == 1) 555 ? new CmpUNode( new_add, range ) 556 : new CmpUNode( range, new_add ); 557 new_cmp = gvn->transform(new_cmp); 558 // See if no need to adjust the existing check 559 if( new_cmp == cmp ) return; 560 // Else, adjust existing check 561 Node *new_bol = gvn->transform( new BoolNode( new_cmp, bol->as_Bool()->_test._test ) ); 562 igvn->rehash_node_delayed( iff ); 563 iff->set_req_X( 1, new_bol, igvn ); 564 } 565 566 //------------------------------up_one_dom------------------------------------- 567 // Walk up the dominator tree one step. Return NULL at root or true 568 // complex merges. Skips through small diamonds. 569 Node* IfNode::up_one_dom(Node *curr, bool linear_only) { 570 Node *dom = curr->in(0); 571 if( !dom ) // Found a Region degraded to a copy? 572 return curr->nonnull_req(); // Skip thru it 573 574 if( curr != dom ) // Normal walk up one step? 575 return dom; 576 577 // Use linear_only if we are still parsing, since we cannot 578 // trust the regions to be fully filled in. 579 if (linear_only) 580 return NULL; 581 582 if( dom->is_Root() ) 583 return NULL; 584 585 // Else hit a Region. Check for a loop header 586 if( dom->is_Loop() ) 587 return dom->in(1); // Skip up thru loops 588 589 // Check for small diamonds 590 Node *din1, *din2, *din3, *din4; 591 if( dom->req() == 3 && // 2-path merge point 592 (din1 = dom ->in(1)) && // Left path exists 593 (din2 = dom ->in(2)) && // Right path exists 594 (din3 = din1->in(0)) && // Left path up one 595 (din4 = din2->in(0)) ) { // Right path up one 596 if( din3->is_Call() && // Handle a slow-path call on either arm 597 (din3 = din3->in(0)) ) 598 din3 = din3->in(0); 599 if( din4->is_Call() && // Handle a slow-path call on either arm 600 (din4 = din4->in(0)) ) 601 din4 = din4->in(0); 602 if( din3 == din4 && din3->is_If() ) 603 return din3; // Skip around diamonds 604 } 605 606 // Give up the search at true merges 607 return NULL; // Dead loop? Or hit root? 608 } 609 610 611 //------------------------------filtered_int_type-------------------------------- 612 // Return a possibly more restrictive type for val based on condition control flow for an if 613 const TypeInt* IfNode::filtered_int_type(PhaseGVN* gvn, Node *val, Node* if_proj) { 614 assert(if_proj && 615 (if_proj->Opcode() == Op_IfTrue || if_proj->Opcode() == Op_IfFalse), "expecting an if projection"); 616 if (if_proj->in(0) && if_proj->in(0)->is_If()) { 617 IfNode* iff = if_proj->in(0)->as_If(); 618 if (iff->in(1) && iff->in(1)->is_Bool()) { 619 BoolNode* bol = iff->in(1)->as_Bool(); 620 if (bol->in(1) && bol->in(1)->is_Cmp()) { 621 const CmpNode* cmp = bol->in(1)->as_Cmp(); 622 if (cmp->in(1) == val) { 623 const TypeInt* cmp2_t = gvn->type(cmp->in(2))->isa_int(); 624 if (cmp2_t != NULL) { 625 jint lo = cmp2_t->_lo; 626 jint hi = cmp2_t->_hi; 627 BoolTest::mask msk = if_proj->Opcode() == Op_IfTrue ? bol->_test._test : bol->_test.negate(); 628 switch (msk) { 629 case BoolTest::ne: 630 // Can't refine type 631 return NULL; 632 case BoolTest::eq: 633 return cmp2_t; 634 case BoolTest::lt: 635 lo = TypeInt::INT->_lo; 636 if (hi - 1 < hi) { 637 hi = hi - 1; 638 } 639 break; 640 case BoolTest::le: 641 lo = TypeInt::INT->_lo; 642 break; 643 case BoolTest::gt: 644 if (lo + 1 > lo) { 645 lo = lo + 1; 646 } 647 hi = TypeInt::INT->_hi; 648 break; 649 case BoolTest::ge: 650 // lo unchanged 651 hi = TypeInt::INT->_hi; 652 break; 653 } 654 const TypeInt* rtn_t = TypeInt::make(lo, hi, cmp2_t->_widen); 655 return rtn_t; 656 } 657 } 658 } 659 } 660 } 661 return NULL; 662 } 663 664 //------------------------------fold_compares---------------------------- 665 // See if a pair of CmpIs can be converted into a CmpU. In some cases 666 // the direction of this if is determined by the preceding if so it 667 // can be eliminate entirely. Given an if testing (CmpI n c) check 668 // for an immediately control dependent if that is testing (CmpI n c2) 669 // and has one projection leading to this if and the other projection 670 // leading to a region that merges one of this ifs control 671 // projections. 672 // 673 // If 674 // / | 675 // / | 676 // / | 677 // If | 678 // /\ | 679 // / \ | 680 // / \ | 681 // / Region 682 // 683 Node* IfNode::fold_compares(PhaseGVN* phase) { 684 if (Opcode() != Op_If) return NULL; 685 686 Node* this_cmp = in(1)->in(1); 687 if (this_cmp != NULL && this_cmp->Opcode() == Op_CmpI && 688 this_cmp->in(2)->is_Con() && this_cmp->in(2) != phase->C->top()) { 689 Node* ctrl = in(0); 690 BoolNode* this_bool = in(1)->as_Bool(); 691 Node* n = this_cmp->in(1); 692 int hi = this_cmp->in(2)->get_int(); 693 if (ctrl != NULL && ctrl->is_Proj() && ctrl->outcnt() == 1 && 694 ctrl->in(0)->is_If() && 695 ctrl->in(0)->outcnt() == 2 && 696 ctrl->in(0)->in(1)->is_Bool() && 697 ctrl->in(0)->in(1)->in(1)->Opcode() == Op_CmpI && 698 ctrl->in(0)->in(1)->in(1)->in(2)->is_Con() && 699 ctrl->in(0)->in(1)->in(1)->in(2) != phase->C->top() && 700 ctrl->in(0)->in(1)->in(1)->in(1) == n) { 701 IfNode* dom_iff = ctrl->in(0)->as_If(); 702 Node* otherproj = dom_iff->proj_out(!ctrl->as_Proj()->_con); 703 if (otherproj->outcnt() == 1 && otherproj->unique_out()->is_Region() && 704 this_bool->_test._test != BoolTest::ne && this_bool->_test._test != BoolTest::eq) { 705 // Identify which proj goes to the region and which continues on 706 RegionNode* region = otherproj->unique_out()->as_Region(); 707 Node* success = NULL; 708 Node* fail = NULL; 709 for (int i = 0; i < 2; i++) { 710 Node* proj = proj_out(i); 711 if (success == NULL && proj->outcnt() == 1 && proj->unique_out() == region) { 712 success = proj; 713 } else if (fail == NULL) { 714 fail = proj; 715 } else { 716 success = fail = NULL; 717 } 718 } 719 if (success != NULL && fail != NULL && !region->has_phi()) { 720 int lo = dom_iff->in(1)->in(1)->in(2)->get_int(); 721 BoolNode* dom_bool = dom_iff->in(1)->as_Bool(); 722 Node* dom_cmp = dom_bool->in(1); 723 const TypeInt* failtype = filtered_int_type(phase, n, ctrl); 724 if (failtype != NULL) { 725 const TypeInt* type2 = filtered_int_type(phase, n, fail); 726 if (type2 != NULL) { 727 failtype = failtype->join(type2)->is_int(); 728 } else { 729 failtype = NULL; 730 } 731 } 732 733 if (failtype != NULL && 734 dom_bool->_test._test != BoolTest::ne && dom_bool->_test._test != BoolTest::eq) { 735 int bound = failtype->_hi - failtype->_lo + 1; 736 if (failtype->_hi != max_jint && failtype->_lo != min_jint && bound > 1) { 737 // Merge the two compares into a single unsigned compare by building (CmpU (n - lo) hi) 738 BoolTest::mask cond = fail->as_Proj()->_con ? BoolTest::lt : BoolTest::ge; 739 Node* adjusted = phase->transform(new SubINode(n, phase->intcon(failtype->_lo))); 740 Node* newcmp = phase->transform(new CmpUNode(adjusted, phase->intcon(bound))); 741 Node* newbool = phase->transform(new BoolNode(newcmp, cond)); 742 phase->is_IterGVN()->replace_input_of(dom_iff, 1, phase->intcon(ctrl->as_Proj()->_con)); 743 phase->hash_delete(this); 744 set_req(1, newbool); 745 return this; 746 } 747 if (failtype->_lo > failtype->_hi) { 748 // previous if determines the result of this if so 749 // replace Bool with constant 750 phase->hash_delete(this); 751 set_req(1, phase->intcon(success->as_Proj()->_con)); 752 return this; 753 } 754 } 755 } 756 } 757 } 758 } 759 return NULL; 760 } 761 762 //------------------------------remove_useless_bool---------------------------- 763 // Check for people making a useless boolean: things like 764 // if( (x < y ? true : false) ) { ... } 765 // Replace with if( x < y ) { ... } 766 static Node *remove_useless_bool(IfNode *iff, PhaseGVN *phase) { 767 Node *i1 = iff->in(1); 768 if( !i1->is_Bool() ) return NULL; 769 BoolNode *bol = i1->as_Bool(); 770 771 Node *cmp = bol->in(1); 772 if( cmp->Opcode() != Op_CmpI ) return NULL; 773 774 // Must be comparing against a bool 775 const Type *cmp2_t = phase->type( cmp->in(2) ); 776 if( cmp2_t != TypeInt::ZERO && 777 cmp2_t != TypeInt::ONE ) 778 return NULL; 779 780 // Find a prior merge point merging the boolean 781 i1 = cmp->in(1); 782 if( !i1->is_Phi() ) return NULL; 783 PhiNode *phi = i1->as_Phi(); 784 if( phase->type( phi ) != TypeInt::BOOL ) 785 return NULL; 786 787 // Check for diamond pattern 788 int true_path = phi->is_diamond_phi(); 789 if( true_path == 0 ) return NULL; 790 791 // Make sure that iff and the control of the phi are different. This 792 // should really only happen for dead control flow since it requires 793 // an illegal cycle. 794 if (phi->in(0)->in(1)->in(0) == iff) return NULL; 795 796 // phi->region->if_proj->ifnode->bool->cmp 797 BoolNode *bol2 = phi->in(0)->in(1)->in(0)->in(1)->as_Bool(); 798 799 // Now get the 'sense' of the test correct so we can plug in 800 // either iff2->in(1) or its complement. 801 int flip = 0; 802 if( bol->_test._test == BoolTest::ne ) flip = 1-flip; 803 else if( bol->_test._test != BoolTest::eq ) return NULL; 804 if( cmp2_t == TypeInt::ZERO ) flip = 1-flip; 805 806 const Type *phi1_t = phase->type( phi->in(1) ); 807 const Type *phi2_t = phase->type( phi->in(2) ); 808 // Check for Phi(0,1) and flip 809 if( phi1_t == TypeInt::ZERO ) { 810 if( phi2_t != TypeInt::ONE ) return NULL; 811 flip = 1-flip; 812 } else { 813 // Check for Phi(1,0) 814 if( phi1_t != TypeInt::ONE ) return NULL; 815 if( phi2_t != TypeInt::ZERO ) return NULL; 816 } 817 if( true_path == 2 ) { 818 flip = 1-flip; 819 } 820 821 Node* new_bol = (flip ? phase->transform( bol2->negate(phase) ) : bol2); 822 assert(new_bol != iff->in(1), "must make progress"); 823 iff->set_req(1, new_bol); 824 // Intervening diamond probably goes dead 825 phase->C->set_major_progress(); 826 return iff; 827 } 828 829 static IfNode* idealize_test(PhaseGVN* phase, IfNode* iff); 830 831 struct RangeCheck { 832 Node* ctl; 833 jint off; 834 }; 835 836 //------------------------------Ideal------------------------------------------ 837 // Return a node which is more "ideal" than the current node. Strip out 838 // control copies 839 Node *IfNode::Ideal(PhaseGVN *phase, bool can_reshape) { 840 if (remove_dead_region(phase, can_reshape)) return this; 841 // No Def-Use info? 842 if (!can_reshape) return NULL; 843 PhaseIterGVN *igvn = phase->is_IterGVN(); 844 845 // Don't bother trying to transform a dead if 846 if (in(0)->is_top()) return NULL; 847 // Don't bother trying to transform an if with a dead test 848 if (in(1)->is_top()) return NULL; 849 // Another variation of a dead test 850 if (in(1)->is_Con()) return NULL; 851 // Another variation of a dead if 852 if (outcnt() < 2) return NULL; 853 854 // Canonicalize the test. 855 Node* idt_if = idealize_test(phase, this); 856 if (idt_if != NULL) return idt_if; 857 858 // Try to split the IF 859 Node *s = split_if(this, igvn); 860 if (s != NULL) return s; 861 862 // Check for people making a useless boolean: things like 863 // if( (x < y ? true : false) ) { ... } 864 // Replace with if( x < y ) { ... } 865 Node *bol2 = remove_useless_bool(this, phase); 866 if( bol2 ) return bol2; 867 868 // Setup to scan up the CFG looking for a dominating test 869 Node *dom = in(0); 870 Node *prev_dom = this; 871 872 // Check for range-check vs other kinds of tests 873 Node *index1, *range1; 874 jint offset1; 875 int flip1 = is_range_check(range1, index1, offset1); 876 if( flip1 ) { 877 // Try to remove extra range checks. All 'up_one_dom' gives up at merges 878 // so all checks we inspect post-dominate the top-most check we find. 879 // If we are going to fail the current check and we reach the top check 880 // then we are guaranteed to fail, so just start interpreting there. 881 // We 'expand' the top 3 range checks to include all post-dominating 882 // checks. 883 884 // The top 3 range checks seen 885 const int NRC =3; 886 RangeCheck prev_checks[NRC]; 887 int nb_checks = 0; 888 889 // Low and high offsets seen so far 890 jint off_lo = offset1; 891 jint off_hi = offset1; 892 893 bool found_immediate_dominator = false; 894 895 // Scan for the top checks and collect range of offsets 896 for (int dist = 0; dist < 999; dist++) { // Range-Check scan limit 897 if (dom->Opcode() == Op_If && // Not same opcode? 898 prev_dom->in(0) == dom) { // One path of test does dominate? 899 if (dom == this) return NULL; // dead loop 900 // See if this is a range check 901 Node *index2, *range2; 902 jint offset2; 903 int flip2 = dom->as_If()->is_range_check(range2, index2, offset2); 904 // See if this is a _matching_ range check, checking against 905 // the same array bounds. 906 if (flip2 == flip1 && range2 == range1 && index2 == index1 && 907 dom->outcnt() == 2) { 908 if (nb_checks == 0 && dom->in(1) == in(1)) { 909 // Found an immediately dominating test at the same offset. 910 // This kind of back-to-back test can be eliminated locally, 911 // and there is no need to search further for dominating tests. 912 assert(offset2 == offset1, "Same test but different offsets"); 913 found_immediate_dominator = true; 914 break; 915 } 916 // Gather expanded bounds 917 off_lo = MIN2(off_lo,offset2); 918 off_hi = MAX2(off_hi,offset2); 919 // Record top NRC range checks 920 prev_checks[nb_checks%NRC].ctl = prev_dom; 921 prev_checks[nb_checks%NRC].off = offset2; 922 nb_checks++; 923 } 924 } 925 prev_dom = dom; 926 dom = up_one_dom(dom); 927 if (!dom) break; 928 } 929 930 if (!found_immediate_dominator) { 931 // Attempt to widen the dominating range check to cover some later 932 // ones. Since range checks "fail" by uncommon-trapping to the 933 // interpreter, widening a check can make us speculatively enter 934 // the interpreter. If we see range-check deopt's, do not widen! 935 if (!phase->C->allow_range_check_smearing()) return NULL; 936 937 // Didn't find prior covering check, so cannot remove anything. 938 if (nb_checks == 0) { 939 return NULL; 940 } 941 // Constant indices only need to check the upper bound. 942 // Non-constant indices must check both low and high. 943 int chk0 = (nb_checks - 1) % NRC; 944 if (index1) { 945 if (nb_checks == 1) { 946 return NULL; 947 } else { 948 // If the top range check's constant is the min or max of 949 // all constants we widen the next one to cover the whole 950 // range of constants. 951 RangeCheck rc0 = prev_checks[chk0]; 952 int chk1 = (nb_checks - 2) % NRC; 953 RangeCheck rc1 = prev_checks[chk1]; 954 if (rc0.off == off_lo) { 955 adjust_check(rc1.ctl, range1, index1, flip1, off_hi, igvn); 956 prev_dom = rc1.ctl; 957 } else if (rc0.off == off_hi) { 958 adjust_check(rc1.ctl, range1, index1, flip1, off_lo, igvn); 959 prev_dom = rc1.ctl; 960 } else { 961 // If the top test's constant is not the min or max of all 962 // constants, we need 3 range checks. We must leave the 963 // top test unchanged because widening it would allow the 964 // accesses it protects to successfully read/write out of 965 // bounds. 966 if (nb_checks == 2) { 967 return NULL; 968 } 969 int chk2 = (nb_checks - 3) % NRC; 970 RangeCheck rc2 = prev_checks[chk2]; 971 // The top range check a+i covers interval: -a <= i < length-a 972 // The second range check b+i covers interval: -b <= i < length-b 973 if (rc1.off <= rc0.off) { 974 // if b <= a, we change the second range check to: 975 // -min_of_all_constants <= i < length-min_of_all_constants 976 // Together top and second range checks now cover: 977 // -min_of_all_constants <= i < length-a 978 // which is more restrictive than -b <= i < length-b: 979 // -b <= -min_of_all_constants <= i < length-a <= length-b 980 // The third check is then changed to: 981 // -max_of_all_constants <= i < length-max_of_all_constants 982 // so 2nd and 3rd checks restrict allowed values of i to: 983 // -min_of_all_constants <= i < length-max_of_all_constants 984 adjust_check(rc1.ctl, range1, index1, flip1, off_lo, igvn); 985 adjust_check(rc2.ctl, range1, index1, flip1, off_hi, igvn); 986 } else { 987 // if b > a, we change the second range check to: 988 // -max_of_all_constants <= i < length-max_of_all_constants 989 // Together top and second range checks now cover: 990 // -a <= i < length-max_of_all_constants 991 // which is more restrictive than -b <= i < length-b: 992 // -b < -a <= i < length-max_of_all_constants <= length-b 993 // The third check is then changed to: 994 // -max_of_all_constants <= i < length-max_of_all_constants 995 // so 2nd and 3rd checks restrict allowed values of i to: 996 // -min_of_all_constants <= i < length-max_of_all_constants 997 adjust_check(rc1.ctl, range1, index1, flip1, off_hi, igvn); 998 adjust_check(rc2.ctl, range1, index1, flip1, off_lo, igvn); 999 } 1000 prev_dom = rc2.ctl; 1001 } 1002 } 1003 } else { 1004 RangeCheck rc0 = prev_checks[chk0]; 1005 // 'Widen' the offset of the 1st and only covering check 1006 adjust_check(rc0.ctl, range1, index1, flip1, off_hi, igvn); 1007 // Test is now covered by prior checks, dominate it out 1008 prev_dom = rc0.ctl; 1009 } 1010 } 1011 1012 } else { // Scan for an equivalent test 1013 1014 Node *cmp; 1015 int dist = 0; // Cutoff limit for search 1016 int op = Opcode(); 1017 if( op == Op_If && 1018 (cmp=in(1)->in(1))->Opcode() == Op_CmpP ) { 1019 if( cmp->in(2) != NULL && // make sure cmp is not already dead 1020 cmp->in(2)->bottom_type() == TypePtr::NULL_PTR ) { 1021 dist = 64; // Limit for null-pointer scans 1022 } else { 1023 dist = 4; // Do not bother for random pointer tests 1024 } 1025 } else { 1026 dist = 4; // Limit for random junky scans 1027 } 1028 1029 // Normal equivalent-test check. 1030 if( !dom ) return NULL; // Dead loop? 1031 1032 Node* result = fold_compares(phase); 1033 if (result != NULL) { 1034 return result; 1035 } 1036 1037 // Search up the dominator tree for an If with an identical test 1038 while( dom->Opcode() != op || // Not same opcode? 1039 dom->in(1) != in(1) || // Not same input 1? 1040 (req() == 3 && dom->in(2) != in(2)) || // Not same input 2? 1041 prev_dom->in(0) != dom ) { // One path of test does not dominate? 1042 if( dist < 0 ) return NULL; 1043 1044 dist--; 1045 prev_dom = dom; 1046 dom = up_one_dom( dom ); 1047 if( !dom ) return NULL; 1048 } 1049 1050 // Check that we did not follow a loop back to ourselves 1051 if( this == dom ) 1052 return NULL; 1053 1054 if( dist > 2 ) // Add to count of NULL checks elided 1055 explicit_null_checks_elided++; 1056 1057 } // End of Else scan for an equivalent test 1058 1059 // Hit! Remove this IF 1060 #ifndef PRODUCT 1061 if( TraceIterativeGVN ) { 1062 tty->print(" Removing IfNode: "); this->dump(); 1063 } 1064 if( VerifyOpto && !phase->allow_progress() ) { 1065 // Found an equivalent dominating test, 1066 // we can not guarantee reaching a fix-point for these during iterativeGVN 1067 // since intervening nodes may not change. 1068 return NULL; 1069 } 1070 #endif 1071 1072 // Replace dominated IfNode 1073 dominated_by( prev_dom, igvn ); 1074 1075 // Must return either the original node (now dead) or a new node 1076 // (Do not return a top here, since that would break the uniqueness of top.) 1077 return new ConINode(TypeInt::ZERO); 1078 } 1079 1080 //------------------------------dominated_by----------------------------------- 1081 void IfNode::dominated_by( Node *prev_dom, PhaseIterGVN *igvn ) { 1082 igvn->hash_delete(this); // Remove self to prevent spurious V-N 1083 Node *idom = in(0); 1084 // Need opcode to decide which way 'this' test goes 1085 int prev_op = prev_dom->Opcode(); 1086 Node *top = igvn->C->top(); // Shortcut to top 1087 1088 // Loop predicates may have depending checks which should not 1089 // be skipped. For example, range check predicate has two checks 1090 // for lower and upper bounds. 1091 ProjNode* unc_proj = proj_out(1 - prev_dom->as_Proj()->_con)->as_Proj(); 1092 if (unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_predicate)) 1093 prev_dom = idom; 1094 1095 // Now walk the current IfNode's projections. 1096 // Loop ends when 'this' has no more uses. 1097 for (DUIterator_Last imin, i = last_outs(imin); i >= imin; --i) { 1098 Node *ifp = last_out(i); // Get IfTrue/IfFalse 1099 igvn->add_users_to_worklist(ifp); 1100 // Check which projection it is and set target. 1101 // Data-target is either the dominating projection of the same type 1102 // or TOP if the dominating projection is of opposite type. 1103 // Data-target will be used as the new control edge for the non-CFG 1104 // nodes like Casts and Loads. 1105 Node *data_target = (ifp->Opcode() == prev_op) ? prev_dom : top; 1106 // Control-target is just the If's immediate dominator or TOP. 1107 Node *ctrl_target = (ifp->Opcode() == prev_op) ? idom : top; 1108 1109 // For each child of an IfTrue/IfFalse projection, reroute. 1110 // Loop ends when projection has no more uses. 1111 for (DUIterator_Last jmin, j = ifp->last_outs(jmin); j >= jmin; --j) { 1112 Node* s = ifp->last_out(j); // Get child of IfTrue/IfFalse 1113 if( !s->depends_only_on_test() ) { 1114 // Find the control input matching this def-use edge. 1115 // For Regions it may not be in slot 0. 1116 uint l; 1117 for( l = 0; s->in(l) != ifp; l++ ) { } 1118 igvn->replace_input_of(s, l, ctrl_target); 1119 } else { // Else, for control producers, 1120 igvn->replace_input_of(s, 0, data_target); // Move child to data-target 1121 } 1122 } // End for each child of a projection 1123 1124 igvn->remove_dead_node(ifp); 1125 } // End for each IfTrue/IfFalse child of If 1126 1127 // Kill the IfNode 1128 igvn->remove_dead_node(this); 1129 } 1130 1131 //------------------------------Identity--------------------------------------- 1132 // If the test is constant & we match, then we are the input Control 1133 Node *IfProjNode::Identity(PhaseTransform *phase) { 1134 // Can only optimize if cannot go the other way 1135 const TypeTuple *t = phase->type(in(0))->is_tuple(); 1136 if (t == TypeTuple::IFNEITHER || 1137 // kill dead branch first otherwise the IfNode's control will 1138 // have 2 control uses (the IfNode that doesn't go away because 1139 // it still has uses and this branch of the 1140 // If). Node::has_special_unique_user() will cause this node to 1141 // be reprocessed once the dead branch is killed. 1142 (always_taken(t) && in(0)->outcnt() == 1)) { 1143 // IfNode control 1144 return in(0)->in(0); 1145 } 1146 // no progress 1147 return this; 1148 } 1149 1150 //------------------------------dump_spec-------------------------------------- 1151 #ifndef PRODUCT 1152 void IfNode::dump_spec(outputStream *st) const { 1153 st->print("P=%f, C=%f",_prob,_fcnt); 1154 } 1155 #endif 1156 1157 //------------------------------idealize_test---------------------------------- 1158 // Try to canonicalize tests better. Peek at the Cmp/Bool/If sequence and 1159 // come up with a canonical sequence. Bools getting 'eq', 'gt' and 'ge' forms 1160 // converted to 'ne', 'le' and 'lt' forms. IfTrue/IfFalse get swapped as 1161 // needed. 1162 static IfNode* idealize_test(PhaseGVN* phase, IfNode* iff) { 1163 assert(iff->in(0) != NULL, "If must be live"); 1164 1165 if (iff->outcnt() != 2) return NULL; // Malformed projections. 1166 Node* old_if_f = iff->proj_out(false); 1167 Node* old_if_t = iff->proj_out(true); 1168 1169 // CountedLoopEnds want the back-control test to be TRUE, irregardless of 1170 // whether they are testing a 'gt' or 'lt' condition. The 'gt' condition 1171 // happens in count-down loops 1172 if (iff->is_CountedLoopEnd()) return NULL; 1173 if (!iff->in(1)->is_Bool()) return NULL; // Happens for partially optimized IF tests 1174 BoolNode *b = iff->in(1)->as_Bool(); 1175 BoolTest bt = b->_test; 1176 // Test already in good order? 1177 if( bt.is_canonical() ) 1178 return NULL; 1179 1180 // Flip test to be canonical. Requires flipping the IfFalse/IfTrue and 1181 // cloning the IfNode. 1182 Node* new_b = phase->transform( new BoolNode(b->in(1), bt.negate()) ); 1183 if( !new_b->is_Bool() ) return NULL; 1184 b = new_b->as_Bool(); 1185 1186 PhaseIterGVN *igvn = phase->is_IterGVN(); 1187 assert( igvn, "Test is not canonical in parser?" ); 1188 1189 // The IF node never really changes, but it needs to be cloned 1190 iff = new IfNode( iff->in(0), b, 1.0-iff->_prob, iff->_fcnt); 1191 1192 Node *prior = igvn->hash_find_insert(iff); 1193 if( prior ) { 1194 igvn->remove_dead_node(iff); 1195 iff = (IfNode*)prior; 1196 } else { 1197 // Cannot call transform on it just yet 1198 igvn->set_type_bottom(iff); 1199 } 1200 igvn->_worklist.push(iff); 1201 1202 // Now handle projections. Cloning not required. 1203 Node* new_if_f = (Node*)(new IfFalseNode( iff )); 1204 Node* new_if_t = (Node*)(new IfTrueNode ( iff )); 1205 1206 igvn->register_new_node_with_optimizer(new_if_f); 1207 igvn->register_new_node_with_optimizer(new_if_t); 1208 // Flip test, so flip trailing control 1209 igvn->replace_node(old_if_f, new_if_t); 1210 igvn->replace_node(old_if_t, new_if_f); 1211 1212 // Progress 1213 return iff; 1214 }