1 /* 2 * Copyright (c) 1997, 2017, 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 "classfile/systemDictionary.hpp" 27 #include "memory/allocation.inline.hpp" 28 #include "memory/resourceArea.hpp" 29 #include "oops/objArrayKlass.hpp" 30 #include "opto/addnode.hpp" 31 #include "opto/castnode.hpp" 32 #include "opto/cfgnode.hpp" 33 #include "opto/connode.hpp" 34 #include "opto/convertnode.hpp" 35 #include "opto/loopnode.hpp" 36 #include "opto/machnode.hpp" 37 #include "opto/movenode.hpp" 38 #include "opto/narrowptrnode.hpp" 39 #include "opto/mulnode.hpp" 40 #include "opto/phaseX.hpp" 41 #include "opto/regmask.hpp" 42 #include "opto/runtime.hpp" 43 #include "opto/subnode.hpp" 44 #include "utilities/vmError.hpp" 45 46 // Portions of code courtesy of Clifford Click 47 48 // Optimization - Graph Style 49 50 //============================================================================= 51 //------------------------------Value------------------------------------------ 52 // Compute the type of the RegionNode. 53 const Type* RegionNode::Value(PhaseGVN* phase) const { 54 for( uint i=1; i<req(); ++i ) { // For all paths in 55 Node *n = in(i); // Get Control source 56 if( !n ) continue; // Missing inputs are TOP 57 if( phase->type(n) == Type::CONTROL ) 58 return Type::CONTROL; 59 } 60 return Type::TOP; // All paths dead? Then so are we 61 } 62 63 //------------------------------Identity--------------------------------------- 64 // Check for Region being Identity. 65 Node* RegionNode::Identity(PhaseGVN* phase) { 66 // Cannot have Region be an identity, even if it has only 1 input. 67 // Phi users cannot have their Region input folded away for them, 68 // since they need to select the proper data input 69 return this; 70 } 71 72 //------------------------------merge_region----------------------------------- 73 // If a Region flows into a Region, merge into one big happy merge. This is 74 // hard to do if there is stuff that has to happen 75 static Node *merge_region(RegionNode *region, PhaseGVN *phase) { 76 if( region->Opcode() != Op_Region ) // Do not do to LoopNodes 77 return NULL; 78 Node *progress = NULL; // Progress flag 79 PhaseIterGVN *igvn = phase->is_IterGVN(); 80 81 uint rreq = region->req(); 82 for( uint i = 1; i < rreq; i++ ) { 83 Node *r = region->in(i); 84 if( r && r->Opcode() == Op_Region && // Found a region? 85 r->in(0) == r && // Not already collapsed? 86 r != region && // Avoid stupid situations 87 r->outcnt() == 2 ) { // Self user and 'region' user only? 88 assert(!r->as_Region()->has_phi(), "no phi users"); 89 if( !progress ) { // No progress 90 if (region->has_phi()) { 91 return NULL; // Only flatten if no Phi users 92 // igvn->hash_delete( phi ); 93 } 94 igvn->hash_delete( region ); 95 progress = region; // Making progress 96 } 97 igvn->hash_delete( r ); 98 99 // Append inputs to 'r' onto 'region' 100 for( uint j = 1; j < r->req(); j++ ) { 101 // Move an input from 'r' to 'region' 102 region->add_req(r->in(j)); 103 r->set_req(j, phase->C->top()); 104 // Update phis of 'region' 105 //for( uint k = 0; k < max; k++ ) { 106 // Node *phi = region->out(k); 107 // if( phi->is_Phi() ) { 108 // phi->add_req(phi->in(i)); 109 // } 110 //} 111 112 rreq++; // One more input to Region 113 } // Found a region to merge into Region 114 igvn->_worklist.push(r); 115 // Clobber pointer to the now dead 'r' 116 region->set_req(i, phase->C->top()); 117 } 118 } 119 120 return progress; 121 } 122 123 124 125 //--------------------------------has_phi-------------------------------------- 126 // Helper function: Return any PhiNode that uses this region or NULL 127 PhiNode* RegionNode::has_phi() const { 128 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) { 129 Node* phi = fast_out(i); 130 if (phi->is_Phi()) { // Check for Phi users 131 assert(phi->in(0) == (Node*)this, "phi uses region only via in(0)"); 132 return phi->as_Phi(); // this one is good enough 133 } 134 } 135 136 return NULL; 137 } 138 139 140 //-----------------------------has_unique_phi---------------------------------- 141 // Helper function: Return the only PhiNode that uses this region or NULL 142 PhiNode* RegionNode::has_unique_phi() const { 143 // Check that only one use is a Phi 144 PhiNode* only_phi = NULL; 145 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) { 146 Node* phi = fast_out(i); 147 if (phi->is_Phi()) { // Check for Phi users 148 assert(phi->in(0) == (Node*)this, "phi uses region only via in(0)"); 149 if (only_phi == NULL) { 150 only_phi = phi->as_Phi(); 151 } else { 152 return NULL; // multiple phis 153 } 154 } 155 } 156 157 return only_phi; 158 } 159 160 161 //------------------------------check_phi_clipping----------------------------- 162 // Helper function for RegionNode's identification of FP clipping 163 // Check inputs to the Phi 164 static bool check_phi_clipping( PhiNode *phi, ConNode * &min, uint &min_idx, ConNode * &max, uint &max_idx, Node * &val, uint &val_idx ) { 165 min = NULL; 166 max = NULL; 167 val = NULL; 168 min_idx = 0; 169 max_idx = 0; 170 val_idx = 0; 171 uint phi_max = phi->req(); 172 if( phi_max == 4 ) { 173 for( uint j = 1; j < phi_max; ++j ) { 174 Node *n = phi->in(j); 175 int opcode = n->Opcode(); 176 switch( opcode ) { 177 case Op_ConI: 178 { 179 if( min == NULL ) { 180 min = n->Opcode() == Op_ConI ? (ConNode*)n : NULL; 181 min_idx = j; 182 } else { 183 max = n->Opcode() == Op_ConI ? (ConNode*)n : NULL; 184 max_idx = j; 185 if( min->get_int() > max->get_int() ) { 186 // Swap min and max 187 ConNode *temp; 188 uint temp_idx; 189 temp = min; min = max; max = temp; 190 temp_idx = min_idx; min_idx = max_idx; max_idx = temp_idx; 191 } 192 } 193 } 194 break; 195 default: 196 { 197 val = n; 198 val_idx = j; 199 } 200 break; 201 } 202 } 203 } 204 return ( min && max && val && (min->get_int() <= 0) && (max->get_int() >=0) ); 205 } 206 207 208 //------------------------------check_if_clipping------------------------------ 209 // Helper function for RegionNode's identification of FP clipping 210 // Check that inputs to Region come from two IfNodes, 211 // 212 // If 213 // False True 214 // If | 215 // False True | 216 // | | | 217 // RegionNode_inputs 218 // 219 static bool check_if_clipping( const RegionNode *region, IfNode * &bot_if, IfNode * &top_if ) { 220 top_if = NULL; 221 bot_if = NULL; 222 223 // Check control structure above RegionNode for (if ( if ) ) 224 Node *in1 = region->in(1); 225 Node *in2 = region->in(2); 226 Node *in3 = region->in(3); 227 // Check that all inputs are projections 228 if( in1->is_Proj() && in2->is_Proj() && in3->is_Proj() ) { 229 Node *in10 = in1->in(0); 230 Node *in20 = in2->in(0); 231 Node *in30 = in3->in(0); 232 // Check that #1 and #2 are ifTrue and ifFalse from same If 233 if( in10 != NULL && in10->is_If() && 234 in20 != NULL && in20->is_If() && 235 in30 != NULL && in30->is_If() && in10 == in20 && 236 (in1->Opcode() != in2->Opcode()) ) { 237 Node *in100 = in10->in(0); 238 Node *in1000 = (in100 != NULL && in100->is_Proj()) ? in100->in(0) : NULL; 239 // Check that control for in10 comes from other branch of IF from in3 240 if( in1000 != NULL && in1000->is_If() && 241 in30 == in1000 && (in3->Opcode() != in100->Opcode()) ) { 242 // Control pattern checks 243 top_if = (IfNode*)in1000; 244 bot_if = (IfNode*)in10; 245 } 246 } 247 } 248 249 return (top_if != NULL); 250 } 251 252 253 //------------------------------check_convf2i_clipping------------------------- 254 // Helper function for RegionNode's identification of FP clipping 255 // Verify that the value input to the phi comes from "ConvF2I; LShift; RShift" 256 static bool check_convf2i_clipping( PhiNode *phi, uint idx, ConvF2INode * &convf2i, Node *min, Node *max) { 257 convf2i = NULL; 258 259 // Check for the RShiftNode 260 Node *rshift = phi->in(idx); 261 assert( rshift, "Previous checks ensure phi input is present"); 262 if( rshift->Opcode() != Op_RShiftI ) { return false; } 263 264 // Check for the LShiftNode 265 Node *lshift = rshift->in(1); 266 assert( lshift, "Previous checks ensure phi input is present"); 267 if( lshift->Opcode() != Op_LShiftI ) { return false; } 268 269 // Check for the ConvF2INode 270 Node *conv = lshift->in(1); 271 if( conv->Opcode() != Op_ConvF2I ) { return false; } 272 273 // Check that shift amounts are only to get sign bits set after F2I 274 jint max_cutoff = max->get_int(); 275 jint min_cutoff = min->get_int(); 276 jint left_shift = lshift->in(2)->get_int(); 277 jint right_shift = rshift->in(2)->get_int(); 278 jint max_post_shift = nth_bit(BitsPerJavaInteger - left_shift - 1); 279 if( left_shift != right_shift || 280 0 > left_shift || left_shift >= BitsPerJavaInteger || 281 max_post_shift < max_cutoff || 282 max_post_shift < -min_cutoff ) { 283 // Shifts are necessary but current transformation eliminates them 284 return false; 285 } 286 287 // OK to return the result of ConvF2I without shifting 288 convf2i = (ConvF2INode*)conv; 289 return true; 290 } 291 292 293 //------------------------------check_compare_clipping------------------------- 294 // Helper function for RegionNode's identification of FP clipping 295 static bool check_compare_clipping( bool less_than, IfNode *iff, ConNode *limit, Node * & input ) { 296 Node *i1 = iff->in(1); 297 if ( !i1->is_Bool() ) { return false; } 298 BoolNode *bool1 = i1->as_Bool(); 299 if( less_than && bool1->_test._test != BoolTest::le ) { return false; } 300 else if( !less_than && bool1->_test._test != BoolTest::lt ) { return false; } 301 const Node *cmpF = bool1->in(1); 302 if( cmpF->Opcode() != Op_CmpF ) { return false; } 303 // Test that the float value being compared against 304 // is equivalent to the int value used as a limit 305 Node *nodef = cmpF->in(2); 306 if( nodef->Opcode() != Op_ConF ) { return false; } 307 jfloat conf = nodef->getf(); 308 jint coni = limit->get_int(); 309 if( ((int)conf) != coni ) { return false; } 310 input = cmpF->in(1); 311 return true; 312 } 313 314 //------------------------------is_unreachable_region-------------------------- 315 // Find if the Region node is reachable from the root. 316 bool RegionNode::is_unreachable_region(PhaseGVN *phase) const { 317 assert(req() == 2, ""); 318 319 // First, cut the simple case of fallthrough region when NONE of 320 // region's phis references itself directly or through a data node. 321 uint max = outcnt(); 322 uint i; 323 for (i = 0; i < max; i++) { 324 Node* phi = raw_out(i); 325 if (phi != NULL && phi->is_Phi()) { 326 assert(phase->eqv(phi->in(0), this) && phi->req() == 2, ""); 327 if (phi->outcnt() == 0) 328 continue; // Safe case - no loops 329 if (phi->outcnt() == 1) { 330 Node* u = phi->raw_out(0); 331 // Skip if only one use is an other Phi or Call or Uncommon trap. 332 // It is safe to consider this case as fallthrough. 333 if (u != NULL && (u->is_Phi() || u->is_CFG())) 334 continue; 335 } 336 // Check when phi references itself directly or through an other node. 337 if (phi->as_Phi()->simple_data_loop_check(phi->in(1)) >= PhiNode::Unsafe) 338 break; // Found possible unsafe data loop. 339 } 340 } 341 if (i >= max) 342 return false; // An unsafe case was NOT found - don't need graph walk. 343 344 // Unsafe case - check if the Region node is reachable from root. 345 ResourceMark rm; 346 347 Arena *a = Thread::current()->resource_area(); 348 Node_List nstack(a); 349 VectorSet visited(a); 350 351 // Mark all control nodes reachable from root outputs 352 Node *n = (Node*)phase->C->root(); 353 nstack.push(n); 354 visited.set(n->_idx); 355 while (nstack.size() != 0) { 356 n = nstack.pop(); 357 uint max = n->outcnt(); 358 for (uint i = 0; i < max; i++) { 359 Node* m = n->raw_out(i); 360 if (m != NULL && m->is_CFG()) { 361 if (phase->eqv(m, this)) { 362 return false; // We reached the Region node - it is not dead. 363 } 364 if (!visited.test_set(m->_idx)) 365 nstack.push(m); 366 } 367 } 368 } 369 370 return true; // The Region node is unreachable - it is dead. 371 } 372 373 bool RegionNode::try_clean_mem_phi(PhaseGVN *phase) { 374 // Incremental inlining + PhaseStringOpts sometimes produce: 375 // 376 // cmpP with 1 top input 377 // | 378 // If 379 // / \ 380 // IfFalse IfTrue /- Some Node 381 // \ / / / 382 // Region / /-MergeMem 383 // \---Phi 384 // 385 // 386 // It's expected by PhaseStringOpts that the Region goes away and is 387 // replaced by If's control input but because there's still a Phi, 388 // the Region stays in the graph. The top input from the cmpP is 389 // propagated forward and a subgraph that is useful goes away. The 390 // code below replaces the Phi with the MergeMem so that the Region 391 // is simplified. 392 393 PhiNode* phi = has_unique_phi(); 394 if (phi && phi->type() == Type::MEMORY && req() == 3 && phi->is_diamond_phi(true)) { 395 MergeMemNode* m = NULL; 396 assert(phi->req() == 3, "same as region"); 397 for (uint i = 1; i < 3; ++i) { 398 Node *mem = phi->in(i); 399 if (mem && mem->is_MergeMem() && in(i)->outcnt() == 1) { 400 // Nothing is control-dependent on path #i except the region itself. 401 m = mem->as_MergeMem(); 402 uint j = 3 - i; 403 Node* other = phi->in(j); 404 if (other && other == m->base_memory()) { 405 // m is a successor memory to other, and is not pinned inside the diamond, so push it out. 406 // This will allow the diamond to collapse completely. 407 phase->is_IterGVN()->replace_node(phi, m); 408 return true; 409 } 410 } 411 } 412 } 413 return false; 414 } 415 416 //------------------------------Ideal------------------------------------------ 417 // Return a node which is more "ideal" than the current node. Must preserve 418 // the CFG, but we can still strip out dead paths. 419 Node *RegionNode::Ideal(PhaseGVN *phase, bool can_reshape) { 420 if( !can_reshape && !in(0) ) return NULL; // Already degraded to a Copy 421 assert(!in(0) || !in(0)->is_Root(), "not a specially hidden merge"); 422 423 // Check for RegionNode with no Phi users and both inputs come from either 424 // arm of the same IF. If found, then the control-flow split is useless. 425 bool has_phis = false; 426 if (can_reshape) { // Need DU info to check for Phi users 427 has_phis = (has_phi() != NULL); // Cache result 428 if (has_phis && try_clean_mem_phi(phase)) { 429 has_phis = false; 430 } 431 432 if (!has_phis) { // No Phi users? Nothing merging? 433 for (uint i = 1; i < req()-1; i++) { 434 Node *if1 = in(i); 435 if( !if1 ) continue; 436 Node *iff = if1->in(0); 437 if( !iff || !iff->is_If() ) continue; 438 for( uint j=i+1; j<req(); j++ ) { 439 if( in(j) && in(j)->in(0) == iff && 440 if1->Opcode() != in(j)->Opcode() ) { 441 // Add the IF Projections to the worklist. They (and the IF itself) 442 // will be eliminated if dead. 443 phase->is_IterGVN()->add_users_to_worklist(iff); 444 set_req(i, iff->in(0));// Skip around the useless IF diamond 445 set_req(j, NULL); 446 return this; // Record progress 447 } 448 } 449 } 450 } 451 } 452 453 // Remove TOP or NULL input paths. If only 1 input path remains, this Region 454 // degrades to a copy. 455 bool add_to_worklist = false; 456 bool modified = false; 457 int cnt = 0; // Count of values merging 458 DEBUG_ONLY( int cnt_orig = req(); ) // Save original inputs count 459 int del_it = 0; // The last input path we delete 460 // For all inputs... 461 for( uint i=1; i<req(); ++i ){// For all paths in 462 Node *n = in(i); // Get the input 463 if( n != NULL ) { 464 // Remove useless control copy inputs 465 if( n->is_Region() && n->as_Region()->is_copy() ) { 466 set_req(i, n->nonnull_req()); 467 modified = true; 468 i--; 469 continue; 470 } 471 if( n->is_Proj() ) { // Remove useless rethrows 472 Node *call = n->in(0); 473 if (call->is_Call() && call->as_Call()->entry_point() == OptoRuntime::rethrow_stub()) { 474 set_req(i, call->in(0)); 475 modified = true; 476 i--; 477 continue; 478 } 479 } 480 if( phase->type(n) == Type::TOP ) { 481 set_req(i, NULL); // Ignore TOP inputs 482 modified = true; 483 i--; 484 continue; 485 } 486 cnt++; // One more value merging 487 488 } else if (can_reshape) { // Else found dead path with DU info 489 PhaseIterGVN *igvn = phase->is_IterGVN(); 490 del_req(i); // Yank path from self 491 del_it = i; 492 uint max = outcnt(); 493 DUIterator j; 494 bool progress = true; 495 while(progress) { // Need to establish property over all users 496 progress = false; 497 for (j = outs(); has_out(j); j++) { 498 Node *n = out(j); 499 if( n->req() != req() && n->is_Phi() ) { 500 assert( n->in(0) == this, "" ); 501 igvn->hash_delete(n); // Yank from hash before hacking edges 502 n->set_req_X(i,NULL,igvn);// Correct DU info 503 n->del_req(i); // Yank path from Phis 504 if( max != outcnt() ) { 505 progress = true; 506 j = refresh_out_pos(j); 507 max = outcnt(); 508 } 509 } 510 } 511 } 512 add_to_worklist = true; 513 i--; 514 } 515 } 516 517 if (can_reshape && cnt == 1) { 518 // Is it dead loop? 519 // If it is LoopNopde it had 2 (+1 itself) inputs and 520 // one of them was cut. The loop is dead if it was EntryContol. 521 // Loop node may have only one input because entry path 522 // is removed in PhaseIdealLoop::Dominators(). 523 assert(!this->is_Loop() || cnt_orig <= 3, "Loop node should have 3 or less inputs"); 524 if ((this->is_Loop() && (del_it == LoopNode::EntryControl || 525 (del_it == 0 && is_unreachable_region(phase)))) || 526 (!this->is_Loop() && has_phis && is_unreachable_region(phase))) { 527 // Yes, the region will be removed during the next step below. 528 // Cut the backedge input and remove phis since no data paths left. 529 // We don't cut outputs to other nodes here since we need to put them 530 // on the worklist. 531 PhaseIterGVN *igvn = phase->is_IterGVN(); 532 if (in(1)->outcnt() == 1) { 533 igvn->_worklist.push(in(1)); 534 } 535 del_req(1); 536 cnt = 0; 537 assert( req() == 1, "no more inputs expected" ); 538 uint max = outcnt(); 539 bool progress = true; 540 Node *top = phase->C->top(); 541 DUIterator j; 542 while(progress) { 543 progress = false; 544 for (j = outs(); has_out(j); j++) { 545 Node *n = out(j); 546 if( n->is_Phi() ) { 547 assert( igvn->eqv(n->in(0), this), "" ); 548 assert( n->req() == 2 && n->in(1) != NULL, "Only one data input expected" ); 549 // Break dead loop data path. 550 // Eagerly replace phis with top to avoid phis copies generation. 551 igvn->replace_node(n, top); 552 if( max != outcnt() ) { 553 progress = true; 554 j = refresh_out_pos(j); 555 max = outcnt(); 556 } 557 } 558 } 559 } 560 add_to_worklist = true; 561 } 562 } 563 if (add_to_worklist) { 564 phase->is_IterGVN()->add_users_to_worklist(this); // Revisit collapsed Phis 565 } 566 567 if( cnt <= 1 ) { // Only 1 path in? 568 set_req(0, NULL); // Null control input for region copy 569 if( cnt == 0 && !can_reshape) { // Parse phase - leave the node as it is. 570 // No inputs or all inputs are NULL. 571 return NULL; 572 } else if (can_reshape) { // Optimization phase - remove the node 573 PhaseIterGVN *igvn = phase->is_IterGVN(); 574 // Strip mined (inner) loop is going away, remove outer loop. 575 if (is_CountedLoop() && 576 as_Loop()->is_strip_mined()) { 577 Node* outer_sfpt = as_CountedLoop()->outer_safepoint(); 578 Node* outer_out = as_CountedLoop()->outer_loop_exit(); 579 if (outer_sfpt != NULL && outer_out != NULL) { 580 Node* in = outer_sfpt->in(0); 581 igvn->replace_node(outer_out, in); 582 LoopNode* outer = as_CountedLoop()->outer_loop(); 583 igvn->replace_input_of(outer, LoopNode::LoopBackControl, igvn->C->top()); 584 } 585 } 586 Node *parent_ctrl; 587 if( cnt == 0 ) { 588 assert( req() == 1, "no inputs expected" ); 589 // During IGVN phase such region will be subsumed by TOP node 590 // so region's phis will have TOP as control node. 591 // Kill phis here to avoid it. PhiNode::is_copy() will be always false. 592 // Also set other user's input to top. 593 parent_ctrl = phase->C->top(); 594 } else { 595 // The fallthrough case since we already checked dead loops above. 596 parent_ctrl = in(1); 597 assert(parent_ctrl != NULL, "Region is a copy of some non-null control"); 598 assert(!igvn->eqv(parent_ctrl, this), "Close dead loop"); 599 } 600 if (!add_to_worklist) 601 igvn->add_users_to_worklist(this); // Check for further allowed opts 602 for (DUIterator_Last imin, i = last_outs(imin); i >= imin; --i) { 603 Node* n = last_out(i); 604 igvn->hash_delete(n); // Remove from worklist before modifying edges 605 if( n->is_Phi() ) { // Collapse all Phis 606 // Eagerly replace phis to avoid copies generation. 607 Node* in; 608 if( cnt == 0 ) { 609 assert( n->req() == 1, "No data inputs expected" ); 610 in = parent_ctrl; // replaced by top 611 } else { 612 assert( n->req() == 2 && n->in(1) != NULL, "Only one data input expected" ); 613 in = n->in(1); // replaced by unique input 614 if( n->as_Phi()->is_unsafe_data_reference(in) ) 615 in = phase->C->top(); // replaced by top 616 } 617 igvn->replace_node(n, in); 618 } 619 else if( n->is_Region() ) { // Update all incoming edges 620 assert( !igvn->eqv(n, this), "Must be removed from DefUse edges"); 621 uint uses_found = 0; 622 for( uint k=1; k < n->req(); k++ ) { 623 if( n->in(k) == this ) { 624 n->set_req(k, parent_ctrl); 625 uses_found++; 626 } 627 } 628 if( uses_found > 1 ) { // (--i) done at the end of the loop. 629 i -= (uses_found - 1); 630 } 631 } 632 else { 633 assert( igvn->eqv(n->in(0), this), "Expect RegionNode to be control parent"); 634 n->set_req(0, parent_ctrl); 635 } 636 #ifdef ASSERT 637 for( uint k=0; k < n->req(); k++ ) { 638 assert( !igvn->eqv(n->in(k), this), "All uses of RegionNode should be gone"); 639 } 640 #endif 641 } 642 // Remove the RegionNode itself from DefUse info 643 igvn->remove_dead_node(this); 644 return NULL; 645 } 646 return this; // Record progress 647 } 648 649 650 // If a Region flows into a Region, merge into one big happy merge. 651 if (can_reshape) { 652 Node *m = merge_region(this, phase); 653 if (m != NULL) return m; 654 } 655 656 // Check if this region is the root of a clipping idiom on floats 657 if( ConvertFloat2IntClipping && can_reshape && req() == 4 ) { 658 // Check that only one use is a Phi and that it simplifies to two constants + 659 PhiNode* phi = has_unique_phi(); 660 if (phi != NULL) { // One Phi user 661 // Check inputs to the Phi 662 ConNode *min; 663 ConNode *max; 664 Node *val; 665 uint min_idx; 666 uint max_idx; 667 uint val_idx; 668 if( check_phi_clipping( phi, min, min_idx, max, max_idx, val, val_idx ) ) { 669 IfNode *top_if; 670 IfNode *bot_if; 671 if( check_if_clipping( this, bot_if, top_if ) ) { 672 // Control pattern checks, now verify compares 673 Node *top_in = NULL; // value being compared against 674 Node *bot_in = NULL; 675 if( check_compare_clipping( true, bot_if, min, bot_in ) && 676 check_compare_clipping( false, top_if, max, top_in ) ) { 677 if( bot_in == top_in ) { 678 PhaseIterGVN *gvn = phase->is_IterGVN(); 679 assert( gvn != NULL, "Only had DefUse info in IterGVN"); 680 // Only remaining check is that bot_in == top_in == (Phi's val + mods) 681 682 // Check for the ConvF2INode 683 ConvF2INode *convf2i; 684 if( check_convf2i_clipping( phi, val_idx, convf2i, min, max ) && 685 convf2i->in(1) == bot_in ) { 686 // Matched pattern, including LShiftI; RShiftI, replace with integer compares 687 // max test 688 Node *cmp = gvn->register_new_node_with_optimizer(new CmpINode( convf2i, min )); 689 Node *boo = gvn->register_new_node_with_optimizer(new BoolNode( cmp, BoolTest::lt )); 690 IfNode *iff = (IfNode*)gvn->register_new_node_with_optimizer(new IfNode( top_if->in(0), boo, PROB_UNLIKELY_MAG(5), top_if->_fcnt )); 691 Node *if_min= gvn->register_new_node_with_optimizer(new IfTrueNode (iff)); 692 Node *ifF = gvn->register_new_node_with_optimizer(new IfFalseNode(iff)); 693 // min test 694 cmp = gvn->register_new_node_with_optimizer(new CmpINode( convf2i, max )); 695 boo = gvn->register_new_node_with_optimizer(new BoolNode( cmp, BoolTest::gt )); 696 iff = (IfNode*)gvn->register_new_node_with_optimizer(new IfNode( ifF, boo, PROB_UNLIKELY_MAG(5), bot_if->_fcnt )); 697 Node *if_max= gvn->register_new_node_with_optimizer(new IfTrueNode (iff)); 698 ifF = gvn->register_new_node_with_optimizer(new IfFalseNode(iff)); 699 // update input edges to region node 700 set_req_X( min_idx, if_min, gvn ); 701 set_req_X( max_idx, if_max, gvn ); 702 set_req_X( val_idx, ifF, gvn ); 703 // remove unnecessary 'LShiftI; RShiftI' idiom 704 gvn->hash_delete(phi); 705 phi->set_req_X( val_idx, convf2i, gvn ); 706 gvn->hash_find_insert(phi); 707 // Return transformed region node 708 return this; 709 } 710 } 711 } 712 } 713 } 714 } 715 } 716 717 return modified ? this : NULL; 718 } 719 720 721 722 const RegMask &RegionNode::out_RegMask() const { 723 return RegMask::Empty; 724 } 725 726 // Find the one non-null required input. RegionNode only 727 Node *Node::nonnull_req() const { 728 assert( is_Region(), "" ); 729 for( uint i = 1; i < _cnt; i++ ) 730 if( in(i) ) 731 return in(i); 732 ShouldNotReachHere(); 733 return NULL; 734 } 735 736 737 //============================================================================= 738 // note that these functions assume that the _adr_type field is flattened 739 uint PhiNode::hash() const { 740 const Type* at = _adr_type; 741 return TypeNode::hash() + (at ? at->hash() : 0); 742 } 743 uint PhiNode::cmp( const Node &n ) const { 744 return TypeNode::cmp(n) && _adr_type == ((PhiNode&)n)._adr_type; 745 } 746 static inline 747 const TypePtr* flatten_phi_adr_type(const TypePtr* at) { 748 if (at == NULL || at == TypePtr::BOTTOM) return at; 749 return Compile::current()->alias_type(at)->adr_type(); 750 } 751 752 //----------------------------make--------------------------------------------- 753 // create a new phi with edges matching r and set (initially) to x 754 PhiNode* PhiNode::make(Node* r, Node* x, const Type *t, const TypePtr* at) { 755 uint preds = r->req(); // Number of predecessor paths 756 assert(t != Type::MEMORY || at == flatten_phi_adr_type(at), "flatten at"); 757 PhiNode* p = new PhiNode(r, t, at); 758 for (uint j = 1; j < preds; j++) { 759 // Fill in all inputs, except those which the region does not yet have 760 if (r->in(j) != NULL) 761 p->init_req(j, x); 762 } 763 return p; 764 } 765 PhiNode* PhiNode::make(Node* r, Node* x) { 766 const Type* t = x->bottom_type(); 767 const TypePtr* at = NULL; 768 if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type()); 769 return make(r, x, t, at); 770 } 771 PhiNode* PhiNode::make_blank(Node* r, Node* x) { 772 const Type* t = x->bottom_type(); 773 const TypePtr* at = NULL; 774 if (t == Type::MEMORY) at = flatten_phi_adr_type(x->adr_type()); 775 return new PhiNode(r, t, at); 776 } 777 778 779 //------------------------slice_memory----------------------------------------- 780 // create a new phi with narrowed memory type 781 PhiNode* PhiNode::slice_memory(const TypePtr* adr_type) const { 782 PhiNode* mem = (PhiNode*) clone(); 783 *(const TypePtr**)&mem->_adr_type = adr_type; 784 // convert self-loops, or else we get a bad graph 785 for (uint i = 1; i < req(); i++) { 786 if ((const Node*)in(i) == this) mem->set_req(i, mem); 787 } 788 mem->verify_adr_type(); 789 return mem; 790 } 791 792 //------------------------split_out_instance----------------------------------- 793 // Split out an instance type from a bottom phi. 794 PhiNode* PhiNode::split_out_instance(const TypePtr* at, PhaseIterGVN *igvn) const { 795 const TypeOopPtr *t_oop = at->isa_oopptr(); 796 assert(t_oop != NULL && t_oop->is_known_instance(), "expecting instance oopptr"); 797 const TypePtr *t = adr_type(); 798 assert(type() == Type::MEMORY && 799 (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM || 800 t->isa_oopptr() && !t->is_oopptr()->is_known_instance() && 801 t->is_oopptr()->cast_to_exactness(true) 802 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr()) 803 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop), 804 "bottom or raw memory required"); 805 806 // Check if an appropriate node already exists. 807 Node *region = in(0); 808 for (DUIterator_Fast kmax, k = region->fast_outs(kmax); k < kmax; k++) { 809 Node* use = region->fast_out(k); 810 if( use->is_Phi()) { 811 PhiNode *phi2 = use->as_Phi(); 812 if (phi2->type() == Type::MEMORY && phi2->adr_type() == at) { 813 return phi2; 814 } 815 } 816 } 817 Compile *C = igvn->C; 818 Arena *a = Thread::current()->resource_area(); 819 Node_Array node_map = new Node_Array(a); 820 Node_Stack stack(a, C->live_nodes() >> 4); 821 PhiNode *nphi = slice_memory(at); 822 igvn->register_new_node_with_optimizer( nphi ); 823 node_map.map(_idx, nphi); 824 stack.push((Node *)this, 1); 825 while(!stack.is_empty()) { 826 PhiNode *ophi = stack.node()->as_Phi(); 827 uint i = stack.index(); 828 assert(i >= 1, "not control edge"); 829 stack.pop(); 830 nphi = node_map[ophi->_idx]->as_Phi(); 831 for (; i < ophi->req(); i++) { 832 Node *in = ophi->in(i); 833 if (in == NULL || igvn->type(in) == Type::TOP) 834 continue; 835 Node *opt = MemNode::optimize_simple_memory_chain(in, t_oop, NULL, igvn); 836 PhiNode *optphi = opt->is_Phi() ? opt->as_Phi() : NULL; 837 if (optphi != NULL && optphi->adr_type() == TypePtr::BOTTOM) { 838 opt = node_map[optphi->_idx]; 839 if (opt == NULL) { 840 stack.push(ophi, i); 841 nphi = optphi->slice_memory(at); 842 igvn->register_new_node_with_optimizer( nphi ); 843 node_map.map(optphi->_idx, nphi); 844 ophi = optphi; 845 i = 0; // will get incremented at top of loop 846 continue; 847 } 848 } 849 nphi->set_req(i, opt); 850 } 851 } 852 return nphi; 853 } 854 855 //------------------------verify_adr_type-------------------------------------- 856 #ifdef ASSERT 857 void PhiNode::verify_adr_type(VectorSet& visited, const TypePtr* at) const { 858 if (visited.test_set(_idx)) return; //already visited 859 860 // recheck constructor invariants: 861 verify_adr_type(false); 862 863 // recheck local phi/phi consistency: 864 assert(_adr_type == at || _adr_type == TypePtr::BOTTOM, 865 "adr_type must be consistent across phi nest"); 866 867 // walk around 868 for (uint i = 1; i < req(); i++) { 869 Node* n = in(i); 870 if (n == NULL) continue; 871 const Node* np = in(i); 872 if (np->is_Phi()) { 873 np->as_Phi()->verify_adr_type(visited, at); 874 } else if (n->bottom_type() == Type::TOP 875 || (n->is_Mem() && n->in(MemNode::Address)->bottom_type() == Type::TOP)) { 876 // ignore top inputs 877 } else { 878 const TypePtr* nat = flatten_phi_adr_type(n->adr_type()); 879 // recheck phi/non-phi consistency at leaves: 880 assert((nat != NULL) == (at != NULL), ""); 881 assert(nat == at || nat == TypePtr::BOTTOM, 882 "adr_type must be consistent at leaves of phi nest"); 883 } 884 } 885 } 886 887 // Verify a whole nest of phis rooted at this one. 888 void PhiNode::verify_adr_type(bool recursive) const { 889 if (VMError::is_error_reported()) return; // muzzle asserts when debugging an error 890 if (Node::in_dump()) return; // muzzle asserts when printing 891 892 assert((_type == Type::MEMORY) == (_adr_type != NULL), "adr_type for memory phis only"); 893 894 if (!VerifyAliases) return; // verify thoroughly only if requested 895 896 assert(_adr_type == flatten_phi_adr_type(_adr_type), 897 "Phi::adr_type must be pre-normalized"); 898 899 if (recursive) { 900 VectorSet visited(Thread::current()->resource_area()); 901 verify_adr_type(visited, _adr_type); 902 } 903 } 904 #endif 905 906 907 //------------------------------Value------------------------------------------ 908 // Compute the type of the PhiNode 909 const Type* PhiNode::Value(PhaseGVN* phase) const { 910 Node *r = in(0); // RegionNode 911 if( !r ) // Copy or dead 912 return in(1) ? phase->type(in(1)) : Type::TOP; 913 914 // Note: During parsing, phis are often transformed before their regions. 915 // This means we have to use type_or_null to defend against untyped regions. 916 if( phase->type_or_null(r) == Type::TOP ) // Dead code? 917 return Type::TOP; 918 919 // Check for trip-counted loop. If so, be smarter. 920 CountedLoopNode* l = r->is_CountedLoop() ? r->as_CountedLoop() : NULL; 921 if (l && ((const Node*)l->phi() == this)) { // Trip counted loop! 922 // protect against init_trip() or limit() returning NULL 923 if (l->can_be_counted_loop(phase)) { 924 const Node *init = l->init_trip(); 925 const Node *limit = l->limit(); 926 const Node* stride = l->stride(); 927 if (init != NULL && limit != NULL && stride != NULL) { 928 const TypeInt* lo = phase->type(init)->isa_int(); 929 const TypeInt* hi = phase->type(limit)->isa_int(); 930 const TypeInt* stride_t = phase->type(stride)->isa_int(); 931 if (lo != NULL && hi != NULL && stride_t != NULL) { // Dying loops might have TOP here 932 assert(stride_t->_hi >= stride_t->_lo, "bad stride type"); 933 BoolTest::mask bt = l->loopexit()->test_trip(); 934 // If the loop exit condition is "not equal", the condition 935 // would not trigger if init > limit (if stride > 0) or if 936 // init < limit if (stride > 0) so we can't deduce bounds 937 // for the iv from the exit condition. 938 if (bt != BoolTest::ne) { 939 if (stride_t->_hi < 0) { // Down-counter loop 940 swap(lo, hi); 941 return TypeInt::make(MIN2(lo->_lo, hi->_lo) , hi->_hi, 3); 942 } else if (stride_t->_lo >= 0) { 943 return TypeInt::make(lo->_lo, MAX2(lo->_hi, hi->_hi), 3); 944 } 945 } 946 } 947 } 948 } else if (l->in(LoopNode::LoopBackControl) != NULL && 949 in(LoopNode::EntryControl) != NULL && 950 phase->type(l->in(LoopNode::LoopBackControl)) == Type::TOP) { 951 // During CCP, if we saturate the type of a counted loop's Phi 952 // before the special code for counted loop above has a chance 953 // to run (that is as long as the type of the backedge's control 954 // is top), we might end up with non monotonic types 955 return phase->type(in(LoopNode::EntryControl))->filter_speculative(_type); 956 } 957 } 958 959 // Until we have harmony between classes and interfaces in the type 960 // lattice, we must tread carefully around phis which implicitly 961 // convert the one to the other. 962 const TypePtr* ttp = _type->make_ptr(); 963 const TypeInstPtr* ttip = (ttp != NULL) ? ttp->isa_instptr() : NULL; 964 const TypeKlassPtr* ttkp = (ttp != NULL) ? ttp->isa_klassptr() : NULL; 965 bool is_intf = false; 966 if (ttip != NULL) { 967 ciKlass* k = ttip->klass(); 968 if (k->is_loaded() && k->is_interface()) 969 is_intf = true; 970 } 971 if (ttkp != NULL) { 972 ciKlass* k = ttkp->klass(); 973 if (k->is_loaded() && k->is_interface()) 974 is_intf = true; 975 } 976 977 // Default case: merge all inputs 978 const Type *t = Type::TOP; // Merged type starting value 979 for (uint i = 1; i < req(); ++i) {// For all paths in 980 // Reachable control path? 981 if (r->in(i) && phase->type(r->in(i)) == Type::CONTROL) { 982 const Type* ti = phase->type(in(i)); 983 // We assume that each input of an interface-valued Phi is a true 984 // subtype of that interface. This might not be true of the meet 985 // of all the input types. The lattice is not distributive in 986 // such cases. Ward off asserts in type.cpp by refusing to do 987 // meets between interfaces and proper classes. 988 const TypePtr* tip = ti->make_ptr(); 989 const TypeInstPtr* tiip = (tip != NULL) ? tip->isa_instptr() : NULL; 990 if (tiip) { 991 bool ti_is_intf = false; 992 ciKlass* k = tiip->klass(); 993 if (k->is_loaded() && k->is_interface()) 994 ti_is_intf = true; 995 if (is_intf != ti_is_intf) 996 { t = _type; break; } 997 } 998 t = t->meet_speculative(ti); 999 } 1000 } 1001 1002 // The worst-case type (from ciTypeFlow) should be consistent with "t". 1003 // That is, we expect that "t->higher_equal(_type)" holds true. 1004 // There are various exceptions: 1005 // - Inputs which are phis might in fact be widened unnecessarily. 1006 // For example, an input might be a widened int while the phi is a short. 1007 // - Inputs might be BotPtrs but this phi is dependent on a null check, 1008 // and postCCP has removed the cast which encodes the result of the check. 1009 // - The type of this phi is an interface, and the inputs are classes. 1010 // - Value calls on inputs might produce fuzzy results. 1011 // (Occurrences of this case suggest improvements to Value methods.) 1012 // 1013 // It is not possible to see Type::BOTTOM values as phi inputs, 1014 // because the ciTypeFlow pre-pass produces verifier-quality types. 1015 const Type* ft = t->filter_speculative(_type); // Worst case type 1016 1017 #ifdef ASSERT 1018 // The following logic has been moved into TypeOopPtr::filter. 1019 const Type* jt = t->join_speculative(_type); 1020 if (jt->empty()) { // Emptied out??? 1021 1022 // Check for evil case of 't' being a class and '_type' expecting an 1023 // interface. This can happen because the bytecodes do not contain 1024 // enough type info to distinguish a Java-level interface variable 1025 // from a Java-level object variable. If we meet 2 classes which 1026 // both implement interface I, but their meet is at 'j/l/O' which 1027 // doesn't implement I, we have no way to tell if the result should 1028 // be 'I' or 'j/l/O'. Thus we'll pick 'j/l/O'. If this then flows 1029 // into a Phi which "knows" it's an Interface type we'll have to 1030 // uplift the type. 1031 if (!t->empty() && ttip && ttip->is_loaded() && ttip->klass()->is_interface()) { 1032 assert(ft == _type, ""); // Uplift to interface 1033 } else if (!t->empty() && ttkp && ttkp->is_loaded() && ttkp->klass()->is_interface()) { 1034 assert(ft == _type, ""); // Uplift to interface 1035 } else { 1036 // We also have to handle 'evil cases' of interface- vs. class-arrays 1037 Type::get_arrays_base_elements(jt, _type, NULL, &ttip); 1038 if (!t->empty() && ttip != NULL && ttip->is_loaded() && ttip->klass()->is_interface()) { 1039 assert(ft == _type, ""); // Uplift to array of interface 1040 } else { 1041 // Otherwise it's something stupid like non-overlapping int ranges 1042 // found on dying counted loops. 1043 assert(ft == Type::TOP, ""); // Canonical empty value 1044 } 1045 } 1046 } 1047 1048 else { 1049 1050 // If we have an interface-typed Phi and we narrow to a class type, the join 1051 // should report back the class. However, if we have a J/L/Object 1052 // class-typed Phi and an interface flows in, it's possible that the meet & 1053 // join report an interface back out. This isn't possible but happens 1054 // because the type system doesn't interact well with interfaces. 1055 const TypePtr *jtp = jt->make_ptr(); 1056 const TypeInstPtr *jtip = (jtp != NULL) ? jtp->isa_instptr() : NULL; 1057 const TypeKlassPtr *jtkp = (jtp != NULL) ? jtp->isa_klassptr() : NULL; 1058 if( jtip && ttip ) { 1059 if( jtip->is_loaded() && jtip->klass()->is_interface() && 1060 ttip->is_loaded() && !ttip->klass()->is_interface() ) { 1061 assert(ft == ttip->cast_to_ptr_type(jtip->ptr()) || 1062 ft->isa_narrowoop() && ft->make_ptr() == ttip->cast_to_ptr_type(jtip->ptr()), ""); 1063 jt = ft; 1064 } 1065 } 1066 if( jtkp && ttkp ) { 1067 if( jtkp->is_loaded() && jtkp->klass()->is_interface() && 1068 !jtkp->klass_is_exact() && // Keep exact interface klass (6894807) 1069 ttkp->is_loaded() && !ttkp->klass()->is_interface() ) { 1070 assert(ft == ttkp->cast_to_ptr_type(jtkp->ptr()) || 1071 ft->isa_narrowklass() && ft->make_ptr() == ttkp->cast_to_ptr_type(jtkp->ptr()), ""); 1072 jt = ft; 1073 } 1074 } 1075 if (jt != ft && jt->base() == ft->base()) { 1076 if (jt->isa_int() && 1077 jt->is_int()->_lo == ft->is_int()->_lo && 1078 jt->is_int()->_hi == ft->is_int()->_hi) 1079 jt = ft; 1080 if (jt->isa_long() && 1081 jt->is_long()->_lo == ft->is_long()->_lo && 1082 jt->is_long()->_hi == ft->is_long()->_hi) 1083 jt = ft; 1084 } 1085 if (jt != ft) { 1086 tty->print("merge type: "); t->dump(); tty->cr(); 1087 tty->print("kill type: "); _type->dump(); tty->cr(); 1088 tty->print("join type: "); jt->dump(); tty->cr(); 1089 tty->print("filter type: "); ft->dump(); tty->cr(); 1090 } 1091 assert(jt == ft, ""); 1092 } 1093 #endif //ASSERT 1094 1095 // Deal with conversion problems found in data loops. 1096 ft = phase->saturate(ft, phase->type_or_null(this), _type); 1097 1098 return ft; 1099 } 1100 1101 1102 //------------------------------is_diamond_phi--------------------------------- 1103 // Does this Phi represent a simple well-shaped diamond merge? Return the 1104 // index of the true path or 0 otherwise. 1105 // If check_control_only is true, do not inspect the If node at the 1106 // top, and return -1 (not an edge number) on success. 1107 int PhiNode::is_diamond_phi(bool check_control_only) const { 1108 // Check for a 2-path merge 1109 Node *region = in(0); 1110 if( !region ) return 0; 1111 if( region->req() != 3 ) return 0; 1112 if( req() != 3 ) return 0; 1113 // Check that both paths come from the same If 1114 Node *ifp1 = region->in(1); 1115 Node *ifp2 = region->in(2); 1116 if( !ifp1 || !ifp2 ) return 0; 1117 Node *iff = ifp1->in(0); 1118 if( !iff || !iff->is_If() ) return 0; 1119 if( iff != ifp2->in(0) ) return 0; 1120 if (check_control_only) return -1; 1121 // Check for a proper bool/cmp 1122 const Node *b = iff->in(1); 1123 if( !b->is_Bool() ) return 0; 1124 const Node *cmp = b->in(1); 1125 if( !cmp->is_Cmp() ) return 0; 1126 1127 // Check for branching opposite expected 1128 if( ifp2->Opcode() == Op_IfTrue ) { 1129 assert( ifp1->Opcode() == Op_IfFalse, "" ); 1130 return 2; 1131 } else { 1132 assert( ifp1->Opcode() == Op_IfTrue, "" ); 1133 return 1; 1134 } 1135 } 1136 1137 //----------------------------check_cmove_id----------------------------------- 1138 // Check for CMove'ing a constant after comparing against the constant. 1139 // Happens all the time now, since if we compare equality vs a constant in 1140 // the parser, we "know" the variable is constant on one path and we force 1141 // it. Thus code like "if( x==0 ) {/*EMPTY*/}" ends up inserting a 1142 // conditional move: "x = (x==0)?0:x;". Yucko. This fix is slightly more 1143 // general in that we don't need constants. Since CMove's are only inserted 1144 // in very special circumstances, we do it here on generic Phi's. 1145 Node* PhiNode::is_cmove_id(PhaseTransform* phase, int true_path) { 1146 assert(true_path !=0, "only diamond shape graph expected"); 1147 1148 // is_diamond_phi() has guaranteed the correctness of the nodes sequence: 1149 // phi->region->if_proj->ifnode->bool->cmp 1150 Node* region = in(0); 1151 Node* iff = region->in(1)->in(0); 1152 BoolNode* b = iff->in(1)->as_Bool(); 1153 Node* cmp = b->in(1); 1154 Node* tval = in(true_path); 1155 Node* fval = in(3-true_path); 1156 Node* id = CMoveNode::is_cmove_id(phase, cmp, tval, fval, b); 1157 if (id == NULL) 1158 return NULL; 1159 1160 // Either value might be a cast that depends on a branch of 'iff'. 1161 // Since the 'id' value will float free of the diamond, either 1162 // decast or return failure. 1163 Node* ctl = id->in(0); 1164 if (ctl != NULL && ctl->in(0) == iff) { 1165 if (id->is_ConstraintCast()) { 1166 return id->in(1); 1167 } else { 1168 // Don't know how to disentangle this value. 1169 return NULL; 1170 } 1171 } 1172 1173 return id; 1174 } 1175 1176 //------------------------------Identity--------------------------------------- 1177 // Check for Region being Identity. 1178 Node* PhiNode::Identity(PhaseGVN* phase) { 1179 // Check for no merging going on 1180 // (There used to be special-case code here when this->region->is_Loop. 1181 // It would check for a tributary phi on the backedge that the main phi 1182 // trivially, perhaps with a single cast. The unique_input method 1183 // does all this and more, by reducing such tributaries to 'this'.) 1184 Node* uin = unique_input(phase, false); 1185 if (uin != NULL) { 1186 return uin; 1187 } 1188 1189 int true_path = is_diamond_phi(); 1190 if (true_path != 0) { 1191 Node* id = is_cmove_id(phase, true_path); 1192 if (id != NULL) return id; 1193 } 1194 1195 return this; // No identity 1196 } 1197 1198 //-----------------------------unique_input------------------------------------ 1199 // Find the unique value, discounting top, self-loops, and casts. 1200 // Return top if there are no inputs, and self if there are multiple. 1201 Node* PhiNode::unique_input(PhaseTransform* phase, bool uncast) { 1202 // 1) One unique direct input, 1203 // or if uncast is true: 1204 // 2) some of the inputs have an intervening ConstraintCast 1205 // 3) an input is a self loop 1206 // 1207 // 1) input or 2) input or 3) input __ 1208 // / \ / \ \ / \ 1209 // \ / | cast phi cast 1210 // phi \ / / \ / 1211 // phi / -- 1212 1213 Node* r = in(0); // RegionNode 1214 if (r == NULL) return in(1); // Already degraded to a Copy 1215 Node* input = NULL; // The unique direct input (maybe uncasted = ConstraintCasts removed) 1216 1217 for (uint i = 1, cnt = req(); i < cnt; ++i) { 1218 Node* rc = r->in(i); 1219 if (rc == NULL || phase->type(rc) == Type::TOP) 1220 continue; // ignore unreachable control path 1221 Node* n = in(i); 1222 if (n == NULL) 1223 continue; 1224 Node* un = n; 1225 if (uncast) { 1226 #ifdef ASSERT 1227 Node* m = un->uncast(); 1228 #endif 1229 while (un != NULL && un->req() == 2 && un->is_ConstraintCast()) { 1230 Node* next = un->in(1); 1231 if (phase->type(next)->isa_rawptr() && phase->type(un)->isa_oopptr()) { 1232 // risk exposing raw ptr at safepoint 1233 break; 1234 } 1235 un = next; 1236 } 1237 assert(m == un || un->in(1) == m, "Only expected at CheckCastPP from allocation"); 1238 } 1239 if (un == NULL || un == this || phase->type(un) == Type::TOP) { 1240 continue; // ignore if top, or in(i) and "this" are in a data cycle 1241 } 1242 // Check for a unique input (maybe uncasted) 1243 if (input == NULL) { 1244 input = un; 1245 } else if (input != un) { 1246 input = NodeSentinel; // no unique input 1247 } 1248 } 1249 if (input == NULL) { 1250 return phase->C->top(); // no inputs 1251 } 1252 1253 if (input != NodeSentinel) { 1254 return input; // one unique direct input 1255 } 1256 1257 // Nothing. 1258 return NULL; 1259 } 1260 1261 //------------------------------is_x2logic------------------------------------- 1262 // Check for simple convert-to-boolean pattern 1263 // If:(C Bool) Region:(IfF IfT) Phi:(Region 0 1) 1264 // Convert Phi to an ConvIB. 1265 static Node *is_x2logic( PhaseGVN *phase, PhiNode *phi, int true_path ) { 1266 assert(true_path !=0, "only diamond shape graph expected"); 1267 // Convert the true/false index into an expected 0/1 return. 1268 // Map 2->0 and 1->1. 1269 int flipped = 2-true_path; 1270 1271 // is_diamond_phi() has guaranteed the correctness of the nodes sequence: 1272 // phi->region->if_proj->ifnode->bool->cmp 1273 Node *region = phi->in(0); 1274 Node *iff = region->in(1)->in(0); 1275 BoolNode *b = (BoolNode*)iff->in(1); 1276 const CmpNode *cmp = (CmpNode*)b->in(1); 1277 1278 Node *zero = phi->in(1); 1279 Node *one = phi->in(2); 1280 const Type *tzero = phase->type( zero ); 1281 const Type *tone = phase->type( one ); 1282 1283 // Check for compare vs 0 1284 const Type *tcmp = phase->type(cmp->in(2)); 1285 if( tcmp != TypeInt::ZERO && tcmp != TypePtr::NULL_PTR ) { 1286 // Allow cmp-vs-1 if the other input is bounded by 0-1 1287 if( !(tcmp == TypeInt::ONE && phase->type(cmp->in(1)) == TypeInt::BOOL) ) 1288 return NULL; 1289 flipped = 1-flipped; // Test is vs 1 instead of 0! 1290 } 1291 1292 // Check for setting zero/one opposite expected 1293 if( tzero == TypeInt::ZERO ) { 1294 if( tone == TypeInt::ONE ) { 1295 } else return NULL; 1296 } else if( tzero == TypeInt::ONE ) { 1297 if( tone == TypeInt::ZERO ) { 1298 flipped = 1-flipped; 1299 } else return NULL; 1300 } else return NULL; 1301 1302 // Check for boolean test backwards 1303 if( b->_test._test == BoolTest::ne ) { 1304 } else if( b->_test._test == BoolTest::eq ) { 1305 flipped = 1-flipped; 1306 } else return NULL; 1307 1308 // Build int->bool conversion 1309 Node *n = new Conv2BNode( cmp->in(1) ); 1310 if( flipped ) 1311 n = new XorINode( phase->transform(n), phase->intcon(1) ); 1312 1313 return n; 1314 } 1315 1316 //------------------------------is_cond_add------------------------------------ 1317 // Check for simple conditional add pattern: "(P < Q) ? X+Y : X;" 1318 // To be profitable the control flow has to disappear; there can be no other 1319 // values merging here. We replace the test-and-branch with: 1320 // "(sgn(P-Q))&Y) + X". Basically, convert "(P < Q)" into 0 or -1 by 1321 // moving the carry bit from (P-Q) into a register with 'sbb EAX,EAX'. 1322 // Then convert Y to 0-or-Y and finally add. 1323 // This is a key transform for SpecJava _201_compress. 1324 static Node* is_cond_add(PhaseGVN *phase, PhiNode *phi, int true_path) { 1325 assert(true_path !=0, "only diamond shape graph expected"); 1326 1327 // is_diamond_phi() has guaranteed the correctness of the nodes sequence: 1328 // phi->region->if_proj->ifnode->bool->cmp 1329 RegionNode *region = (RegionNode*)phi->in(0); 1330 Node *iff = region->in(1)->in(0); 1331 BoolNode* b = iff->in(1)->as_Bool(); 1332 const CmpNode *cmp = (CmpNode*)b->in(1); 1333 1334 // Make sure only merging this one phi here 1335 if (region->has_unique_phi() != phi) return NULL; 1336 1337 // Make sure each arm of the diamond has exactly one output, which we assume 1338 // is the region. Otherwise, the control flow won't disappear. 1339 if (region->in(1)->outcnt() != 1) return NULL; 1340 if (region->in(2)->outcnt() != 1) return NULL; 1341 1342 // Check for "(P < Q)" of type signed int 1343 if (b->_test._test != BoolTest::lt) return NULL; 1344 if (cmp->Opcode() != Op_CmpI) return NULL; 1345 1346 Node *p = cmp->in(1); 1347 Node *q = cmp->in(2); 1348 Node *n1 = phi->in( true_path); 1349 Node *n2 = phi->in(3-true_path); 1350 1351 int op = n1->Opcode(); 1352 if( op != Op_AddI // Need zero as additive identity 1353 /*&&op != Op_SubI && 1354 op != Op_AddP && 1355 op != Op_XorI && 1356 op != Op_OrI*/ ) 1357 return NULL; 1358 1359 Node *x = n2; 1360 Node *y = NULL; 1361 if( x == n1->in(1) ) { 1362 y = n1->in(2); 1363 } else if( x == n1->in(2) ) { 1364 y = n1->in(1); 1365 } else return NULL; 1366 1367 // Not so profitable if compare and add are constants 1368 if( q->is_Con() && phase->type(q) != TypeInt::ZERO && y->is_Con() ) 1369 return NULL; 1370 1371 Node *cmplt = phase->transform( new CmpLTMaskNode(p,q) ); 1372 Node *j_and = phase->transform( new AndINode(cmplt,y) ); 1373 return new AddINode(j_and,x); 1374 } 1375 1376 //------------------------------is_absolute------------------------------------ 1377 // Check for absolute value. 1378 static Node* is_absolute( PhaseGVN *phase, PhiNode *phi_root, int true_path) { 1379 assert(true_path !=0, "only diamond shape graph expected"); 1380 1381 int cmp_zero_idx = 0; // Index of compare input where to look for zero 1382 int phi_x_idx = 0; // Index of phi input where to find naked x 1383 1384 // ABS ends with the merge of 2 control flow paths. 1385 // Find the false path from the true path. With only 2 inputs, 3 - x works nicely. 1386 int false_path = 3 - true_path; 1387 1388 // is_diamond_phi() has guaranteed the correctness of the nodes sequence: 1389 // phi->region->if_proj->ifnode->bool->cmp 1390 BoolNode *bol = phi_root->in(0)->in(1)->in(0)->in(1)->as_Bool(); 1391 1392 // Check bool sense 1393 switch( bol->_test._test ) { 1394 case BoolTest::lt: cmp_zero_idx = 1; phi_x_idx = true_path; break; 1395 case BoolTest::le: cmp_zero_idx = 2; phi_x_idx = false_path; break; 1396 case BoolTest::gt: cmp_zero_idx = 2; phi_x_idx = true_path; break; 1397 case BoolTest::ge: cmp_zero_idx = 1; phi_x_idx = false_path; break; 1398 default: return NULL; break; 1399 } 1400 1401 // Test is next 1402 Node *cmp = bol->in(1); 1403 const Type *tzero = NULL; 1404 switch( cmp->Opcode() ) { 1405 case Op_CmpF: tzero = TypeF::ZERO; break; // Float ABS 1406 case Op_CmpD: tzero = TypeD::ZERO; break; // Double ABS 1407 default: return NULL; 1408 } 1409 1410 // Find zero input of compare; the other input is being abs'd 1411 Node *x = NULL; 1412 bool flip = false; 1413 if( phase->type(cmp->in(cmp_zero_idx)) == tzero ) { 1414 x = cmp->in(3 - cmp_zero_idx); 1415 } else if( phase->type(cmp->in(3 - cmp_zero_idx)) == tzero ) { 1416 // The test is inverted, we should invert the result... 1417 x = cmp->in(cmp_zero_idx); 1418 flip = true; 1419 } else { 1420 return NULL; 1421 } 1422 1423 // Next get the 2 pieces being selected, one is the original value 1424 // and the other is the negated value. 1425 if( phi_root->in(phi_x_idx) != x ) return NULL; 1426 1427 // Check other phi input for subtract node 1428 Node *sub = phi_root->in(3 - phi_x_idx); 1429 1430 // Allow only Sub(0,X) and fail out for all others; Neg is not OK 1431 if( tzero == TypeF::ZERO ) { 1432 if( sub->Opcode() != Op_SubF || 1433 sub->in(2) != x || 1434 phase->type(sub->in(1)) != tzero ) return NULL; 1435 x = new AbsFNode(x); 1436 if (flip) { 1437 x = new SubFNode(sub->in(1), phase->transform(x)); 1438 } 1439 } else { 1440 if( sub->Opcode() != Op_SubD || 1441 sub->in(2) != x || 1442 phase->type(sub->in(1)) != tzero ) return NULL; 1443 x = new AbsDNode(x); 1444 if (flip) { 1445 x = new SubDNode(sub->in(1), phase->transform(x)); 1446 } 1447 } 1448 1449 return x; 1450 } 1451 1452 //------------------------------split_once------------------------------------- 1453 // Helper for split_flow_path 1454 static void split_once(PhaseIterGVN *igvn, Node *phi, Node *val, Node *n, Node *newn) { 1455 igvn->hash_delete(n); // Remove from hash before hacking edges 1456 1457 uint j = 1; 1458 for (uint i = phi->req()-1; i > 0; i--) { 1459 if (phi->in(i) == val) { // Found a path with val? 1460 // Add to NEW Region/Phi, no DU info 1461 newn->set_req( j++, n->in(i) ); 1462 // Remove from OLD Region/Phi 1463 n->del_req(i); 1464 } 1465 } 1466 1467 // Register the new node but do not transform it. Cannot transform until the 1468 // entire Region/Phi conglomerate has been hacked as a single huge transform. 1469 igvn->register_new_node_with_optimizer( newn ); 1470 1471 // Now I can point to the new node. 1472 n->add_req(newn); 1473 igvn->_worklist.push(n); 1474 } 1475 1476 //------------------------------split_flow_path-------------------------------- 1477 // Check for merging identical values and split flow paths 1478 static Node* split_flow_path(PhaseGVN *phase, PhiNode *phi) { 1479 BasicType bt = phi->type()->basic_type(); 1480 if( bt == T_ILLEGAL || type2size[bt] <= 0 ) 1481 return NULL; // Bail out on funny non-value stuff 1482 if( phi->req() <= 3 ) // Need at least 2 matched inputs and a 1483 return NULL; // third unequal input to be worth doing 1484 1485 // Scan for a constant 1486 uint i; 1487 for( i = 1; i < phi->req()-1; i++ ) { 1488 Node *n = phi->in(i); 1489 if( !n ) return NULL; 1490 if( phase->type(n) == Type::TOP ) return NULL; 1491 if( n->Opcode() == Op_ConP || n->Opcode() == Op_ConN || n->Opcode() == Op_ConNKlass ) 1492 break; 1493 } 1494 if( i >= phi->req() ) // Only split for constants 1495 return NULL; 1496 1497 Node *val = phi->in(i); // Constant to split for 1498 uint hit = 0; // Number of times it occurs 1499 Node *r = phi->region(); 1500 1501 for( ; i < phi->req(); i++ ){ // Count occurrences of constant 1502 Node *n = phi->in(i); 1503 if( !n ) return NULL; 1504 if( phase->type(n) == Type::TOP ) return NULL; 1505 if( phi->in(i) == val ) { 1506 hit++; 1507 if (PhaseIdealLoop::find_predicate(r->in(i)) != NULL) { 1508 return NULL; // don't split loop entry path 1509 } 1510 } 1511 } 1512 1513 if( hit <= 1 || // Make sure we find 2 or more 1514 hit == phi->req()-1 ) // and not ALL the same value 1515 return NULL; 1516 1517 // Now start splitting out the flow paths that merge the same value. 1518 // Split first the RegionNode. 1519 PhaseIterGVN *igvn = phase->is_IterGVN(); 1520 RegionNode *newr = new RegionNode(hit+1); 1521 split_once(igvn, phi, val, r, newr); 1522 1523 // Now split all other Phis than this one 1524 for (DUIterator_Fast kmax, k = r->fast_outs(kmax); k < kmax; k++) { 1525 Node* phi2 = r->fast_out(k); 1526 if( phi2->is_Phi() && phi2->as_Phi() != phi ) { 1527 PhiNode *newphi = PhiNode::make_blank(newr, phi2); 1528 split_once(igvn, phi, val, phi2, newphi); 1529 } 1530 } 1531 1532 // Clean up this guy 1533 igvn->hash_delete(phi); 1534 for( i = phi->req()-1; i > 0; i-- ) { 1535 if( phi->in(i) == val ) { 1536 phi->del_req(i); 1537 } 1538 } 1539 phi->add_req(val); 1540 1541 return phi; 1542 } 1543 1544 //============================================================================= 1545 //------------------------------simple_data_loop_check------------------------- 1546 // Try to determining if the phi node in a simple safe/unsafe data loop. 1547 // Returns: 1548 // enum LoopSafety { Safe = 0, Unsafe, UnsafeLoop }; 1549 // Safe - safe case when the phi and it's inputs reference only safe data 1550 // nodes; 1551 // Unsafe - the phi and it's inputs reference unsafe data nodes but there 1552 // is no reference back to the phi - need a graph walk 1553 // to determine if it is in a loop; 1554 // UnsafeLoop - unsafe case when the phi references itself directly or through 1555 // unsafe data node. 1556 // Note: a safe data node is a node which could/never reference itself during 1557 // GVN transformations. For now it is Con, Proj, Phi, CastPP, CheckCastPP. 1558 // I mark Phi nodes as safe node not only because they can reference itself 1559 // but also to prevent mistaking the fallthrough case inside an outer loop 1560 // as dead loop when the phi references itselfs through an other phi. 1561 PhiNode::LoopSafety PhiNode::simple_data_loop_check(Node *in) const { 1562 // It is unsafe loop if the phi node references itself directly. 1563 if (in == (Node*)this) 1564 return UnsafeLoop; // Unsafe loop 1565 // Unsafe loop if the phi node references itself through an unsafe data node. 1566 // Exclude cases with null inputs or data nodes which could reference 1567 // itself (safe for dead loops). 1568 if (in != NULL && !in->is_dead_loop_safe()) { 1569 // Check inputs of phi's inputs also. 1570 // It is much less expensive then full graph walk. 1571 uint cnt = in->req(); 1572 uint i = (in->is_Proj() && !in->is_CFG()) ? 0 : 1; 1573 for (; i < cnt; ++i) { 1574 Node* m = in->in(i); 1575 if (m == (Node*)this) 1576 return UnsafeLoop; // Unsafe loop 1577 if (m != NULL && !m->is_dead_loop_safe()) { 1578 // Check the most common case (about 30% of all cases): 1579 // phi->Load/Store->AddP->(ConP ConP Con)/(Parm Parm Con). 1580 Node *m1 = (m->is_AddP() && m->req() > 3) ? m->in(1) : NULL; 1581 if (m1 == (Node*)this) 1582 return UnsafeLoop; // Unsafe loop 1583 if (m1 != NULL && m1 == m->in(2) && 1584 m1->is_dead_loop_safe() && m->in(3)->is_Con()) { 1585 continue; // Safe case 1586 } 1587 // The phi references an unsafe node - need full analysis. 1588 return Unsafe; 1589 } 1590 } 1591 } 1592 return Safe; // Safe case - we can optimize the phi node. 1593 } 1594 1595 //------------------------------is_unsafe_data_reference----------------------- 1596 // If phi can be reached through the data input - it is data loop. 1597 bool PhiNode::is_unsafe_data_reference(Node *in) const { 1598 assert(req() > 1, ""); 1599 // First, check simple cases when phi references itself directly or 1600 // through an other node. 1601 LoopSafety safety = simple_data_loop_check(in); 1602 if (safety == UnsafeLoop) 1603 return true; // phi references itself - unsafe loop 1604 else if (safety == Safe) 1605 return false; // Safe case - phi could be replaced with the unique input. 1606 1607 // Unsafe case when we should go through data graph to determine 1608 // if the phi references itself. 1609 1610 ResourceMark rm; 1611 1612 Arena *a = Thread::current()->resource_area(); 1613 Node_List nstack(a); 1614 VectorSet visited(a); 1615 1616 nstack.push(in); // Start with unique input. 1617 visited.set(in->_idx); 1618 while (nstack.size() != 0) { 1619 Node* n = nstack.pop(); 1620 uint cnt = n->req(); 1621 uint i = (n->is_Proj() && !n->is_CFG()) ? 0 : 1; 1622 for (; i < cnt; i++) { 1623 Node* m = n->in(i); 1624 if (m == (Node*)this) { 1625 return true; // Data loop 1626 } 1627 if (m != NULL && !m->is_dead_loop_safe()) { // Only look for unsafe cases. 1628 if (!visited.test_set(m->_idx)) 1629 nstack.push(m); 1630 } 1631 } 1632 } 1633 return false; // The phi is not reachable from its inputs 1634 } 1635 1636 1637 //------------------------------Ideal------------------------------------------ 1638 // Return a node which is more "ideal" than the current node. Must preserve 1639 // the CFG, but we can still strip out dead paths. 1640 Node *PhiNode::Ideal(PhaseGVN *phase, bool can_reshape) { 1641 // The next should never happen after 6297035 fix. 1642 if( is_copy() ) // Already degraded to a Copy ? 1643 return NULL; // No change 1644 1645 Node *r = in(0); // RegionNode 1646 assert(r->in(0) == NULL || !r->in(0)->is_Root(), "not a specially hidden merge"); 1647 1648 // Note: During parsing, phis are often transformed before their regions. 1649 // This means we have to use type_or_null to defend against untyped regions. 1650 if( phase->type_or_null(r) == Type::TOP ) // Dead code? 1651 return NULL; // No change 1652 1653 Node *top = phase->C->top(); 1654 bool new_phi = (outcnt() == 0); // transforming new Phi 1655 // No change for igvn if new phi is not hooked 1656 if (new_phi && can_reshape) 1657 return NULL; 1658 1659 // The are 2 situations when only one valid phi's input is left 1660 // (in addition to Region input). 1661 // One: region is not loop - replace phi with this input. 1662 // Two: region is loop - replace phi with top since this data path is dead 1663 // and we need to break the dead data loop. 1664 Node* progress = NULL; // Record if any progress made 1665 for( uint j = 1; j < req(); ++j ){ // For all paths in 1666 // Check unreachable control paths 1667 Node* rc = r->in(j); 1668 Node* n = in(j); // Get the input 1669 if (rc == NULL || phase->type(rc) == Type::TOP) { 1670 if (n != top) { // Not already top? 1671 PhaseIterGVN *igvn = phase->is_IterGVN(); 1672 if (can_reshape && igvn != NULL) { 1673 igvn->_worklist.push(r); 1674 } 1675 set_req(j, top); // Nuke it down 1676 progress = this; // Record progress 1677 } 1678 } 1679 } 1680 1681 if (can_reshape && outcnt() == 0) { 1682 // set_req() above may kill outputs if Phi is referenced 1683 // only by itself on the dead (top) control path. 1684 return top; 1685 } 1686 1687 bool uncasted = false; 1688 Node* uin = unique_input(phase, false); 1689 if (uin == NULL && can_reshape) { 1690 uncasted = true; 1691 uin = unique_input(phase, true); 1692 } 1693 if (uin == top) { // Simplest case: no alive inputs. 1694 if (can_reshape) // IGVN transformation 1695 return top; 1696 else 1697 return NULL; // Identity will return TOP 1698 } else if (uin != NULL) { 1699 // Only one not-NULL unique input path is left. 1700 // Determine if this input is backedge of a loop. 1701 // (Skip new phis which have no uses and dead regions). 1702 if (outcnt() > 0 && r->in(0) != NULL) { 1703 // First, take the short cut when we know it is a loop and 1704 // the EntryControl data path is dead. 1705 // Loop node may have only one input because entry path 1706 // is removed in PhaseIdealLoop::Dominators(). 1707 assert(!r->is_Loop() || r->req() <= 3, "Loop node should have 3 or less inputs"); 1708 bool is_loop = (r->is_Loop() && r->req() == 3); 1709 // Then, check if there is a data loop when phi references itself directly 1710 // or through other data nodes. 1711 if ((is_loop && !uin->eqv_uncast(in(LoopNode::EntryControl))) || 1712 (!is_loop && is_unsafe_data_reference(uin))) { 1713 // Break this data loop to avoid creation of a dead loop. 1714 if (can_reshape) { 1715 return top; 1716 } else { 1717 // We can't return top if we are in Parse phase - cut inputs only 1718 // let Identity to handle the case. 1719 replace_edge(uin, top); 1720 return NULL; 1721 } 1722 } 1723 } 1724 1725 if (uncasted) { 1726 // Add cast nodes between the phi to be removed and its unique input. 1727 // Wait until after parsing for the type information to propagate from the casts. 1728 assert(can_reshape, "Invalid during parsing"); 1729 const Type* phi_type = bottom_type(); 1730 assert(phi_type->isa_int() || phi_type->isa_ptr(), "bad phi type"); 1731 // Add casts to carry the control dependency of the Phi that is 1732 // going away 1733 Node* cast = NULL; 1734 if (phi_type->isa_int()) { 1735 cast = ConstraintCastNode::make_cast(Op_CastII, r, uin, phi_type, true); 1736 } else { 1737 const Type* uin_type = phase->type(uin); 1738 if (!phi_type->isa_oopptr() && !uin_type->isa_oopptr()) { 1739 cast = ConstraintCastNode::make_cast(Op_CastPP, r, uin, phi_type, true); 1740 } else { 1741 // Use a CastPP for a cast to not null and a CheckCastPP for 1742 // a cast to a new klass (and both if both null-ness and 1743 // klass change). 1744 1745 // If the type of phi is not null but the type of uin may be 1746 // null, uin's type must be casted to not null 1747 if (phi_type->join(TypePtr::NOTNULL) == phi_type->remove_speculative() && 1748 uin_type->join(TypePtr::NOTNULL) != uin_type->remove_speculative()) { 1749 cast = ConstraintCastNode::make_cast(Op_CastPP, r, uin, TypePtr::NOTNULL, true); 1750 } 1751 1752 // If the type of phi and uin, both casted to not null, 1753 // differ the klass of uin must be (check)cast'ed to match 1754 // that of phi 1755 if (phi_type->join_speculative(TypePtr::NOTNULL) != uin_type->join_speculative(TypePtr::NOTNULL)) { 1756 Node* n = uin; 1757 if (cast != NULL) { 1758 cast = phase->transform(cast); 1759 n = cast; 1760 } 1761 cast = ConstraintCastNode::make_cast(Op_CheckCastPP, r, n, phi_type, true); 1762 } 1763 if (cast == NULL) { 1764 cast = ConstraintCastNode::make_cast(Op_CastPP, r, uin, phi_type, true); 1765 } 1766 } 1767 } 1768 assert(cast != NULL, "cast should be set"); 1769 cast = phase->transform(cast); 1770 // set all inputs to the new cast(s) so the Phi is removed by Identity 1771 PhaseIterGVN* igvn = phase->is_IterGVN(); 1772 for (uint i = 1; i < req(); i++) { 1773 set_req_X(i, cast, igvn); 1774 } 1775 uin = cast; 1776 } 1777 1778 // One unique input. 1779 debug_only(Node* ident = Identity(phase)); 1780 // The unique input must eventually be detected by the Identity call. 1781 #ifdef ASSERT 1782 if (ident != uin && !ident->is_top()) { 1783 // print this output before failing assert 1784 r->dump(3); 1785 this->dump(3); 1786 ident->dump(); 1787 uin->dump(); 1788 } 1789 #endif 1790 assert(ident == uin || ident->is_top(), "Identity must clean this up"); 1791 return NULL; 1792 } 1793 1794 Node* opt = NULL; 1795 int true_path = is_diamond_phi(); 1796 if( true_path != 0 ) { 1797 // Check for CMove'ing identity. If it would be unsafe, 1798 // handle it here. In the safe case, let Identity handle it. 1799 Node* unsafe_id = is_cmove_id(phase, true_path); 1800 if( unsafe_id != NULL && is_unsafe_data_reference(unsafe_id) ) 1801 opt = unsafe_id; 1802 1803 // Check for simple convert-to-boolean pattern 1804 if( opt == NULL ) 1805 opt = is_x2logic(phase, this, true_path); 1806 1807 // Check for absolute value 1808 if( opt == NULL ) 1809 opt = is_absolute(phase, this, true_path); 1810 1811 // Check for conditional add 1812 if( opt == NULL && can_reshape ) 1813 opt = is_cond_add(phase, this, true_path); 1814 1815 // These 4 optimizations could subsume the phi: 1816 // have to check for a dead data loop creation. 1817 if( opt != NULL ) { 1818 if( opt == unsafe_id || is_unsafe_data_reference(opt) ) { 1819 // Found dead loop. 1820 if( can_reshape ) 1821 return top; 1822 // We can't return top if we are in Parse phase - cut inputs only 1823 // to stop further optimizations for this phi. Identity will return TOP. 1824 assert(req() == 3, "only diamond merge phi here"); 1825 set_req(1, top); 1826 set_req(2, top); 1827 return NULL; 1828 } else { 1829 return opt; 1830 } 1831 } 1832 } 1833 1834 // Check for merging identical values and split flow paths 1835 if (can_reshape) { 1836 opt = split_flow_path(phase, this); 1837 // This optimization only modifies phi - don't need to check for dead loop. 1838 assert(opt == NULL || phase->eqv(opt, this), "do not elide phi"); 1839 if (opt != NULL) return opt; 1840 } 1841 1842 if (in(1) != NULL && in(1)->Opcode() == Op_AddP && can_reshape) { 1843 // Try to undo Phi of AddP: 1844 // (Phi (AddP base base y) (AddP base2 base2 y)) 1845 // becomes: 1846 // newbase := (Phi base base2) 1847 // (AddP newbase newbase y) 1848 // 1849 // This occurs as a result of unsuccessful split_thru_phi and 1850 // interferes with taking advantage of addressing modes. See the 1851 // clone_shift_expressions code in matcher.cpp 1852 Node* addp = in(1); 1853 const Type* type = addp->in(AddPNode::Base)->bottom_type(); 1854 Node* y = addp->in(AddPNode::Offset); 1855 if (y != NULL && addp->in(AddPNode::Base) == addp->in(AddPNode::Address)) { 1856 // make sure that all the inputs are similar to the first one, 1857 // i.e. AddP with base == address and same offset as first AddP 1858 bool doit = true; 1859 for (uint i = 2; i < req(); i++) { 1860 if (in(i) == NULL || 1861 in(i)->Opcode() != Op_AddP || 1862 in(i)->in(AddPNode::Base) != in(i)->in(AddPNode::Address) || 1863 in(i)->in(AddPNode::Offset) != y) { 1864 doit = false; 1865 break; 1866 } 1867 // Accumulate type for resulting Phi 1868 type = type->meet_speculative(in(i)->in(AddPNode::Base)->bottom_type()); 1869 } 1870 Node* base = NULL; 1871 if (doit) { 1872 // Check for neighboring AddP nodes in a tree. 1873 // If they have a base, use that it. 1874 for (DUIterator_Fast kmax, k = this->fast_outs(kmax); k < kmax; k++) { 1875 Node* u = this->fast_out(k); 1876 if (u->is_AddP()) { 1877 Node* base2 = u->in(AddPNode::Base); 1878 if (base2 != NULL && !base2->is_top()) { 1879 if (base == NULL) 1880 base = base2; 1881 else if (base != base2) 1882 { doit = false; break; } 1883 } 1884 } 1885 } 1886 } 1887 if (doit) { 1888 if (base == NULL) { 1889 base = new PhiNode(in(0), type, NULL); 1890 for (uint i = 1; i < req(); i++) { 1891 base->init_req(i, in(i)->in(AddPNode::Base)); 1892 } 1893 phase->is_IterGVN()->register_new_node_with_optimizer(base); 1894 } 1895 return new AddPNode(base, base, y); 1896 } 1897 } 1898 } 1899 1900 // Split phis through memory merges, so that the memory merges will go away. 1901 // Piggy-back this transformation on the search for a unique input.... 1902 // It will be as if the merged memory is the unique value of the phi. 1903 // (Do not attempt this optimization unless parsing is complete. 1904 // It would make the parser's memory-merge logic sick.) 1905 // (MergeMemNode is not dead_loop_safe - need to check for dead loop.) 1906 if (progress == NULL && can_reshape && type() == Type::MEMORY) { 1907 // see if this phi should be sliced 1908 uint merge_width = 0; 1909 bool saw_self = false; 1910 for( uint i=1; i<req(); ++i ) {// For all paths in 1911 Node *ii = in(i); 1912 // TOP inputs should not be counted as safe inputs because if the 1913 // Phi references itself through all other inputs then splitting the 1914 // Phi through memory merges would create dead loop at later stage. 1915 if (ii == top) { 1916 return NULL; // Delay optimization until graph is cleaned. 1917 } 1918 if (ii->is_MergeMem()) { 1919 MergeMemNode* n = ii->as_MergeMem(); 1920 merge_width = MAX2(merge_width, n->req()); 1921 saw_self = saw_self || phase->eqv(n->base_memory(), this); 1922 } 1923 } 1924 1925 // This restriction is temporarily necessary to ensure termination: 1926 if (!saw_self && adr_type() == TypePtr::BOTTOM) merge_width = 0; 1927 1928 if (merge_width > Compile::AliasIdxRaw) { 1929 // found at least one non-empty MergeMem 1930 const TypePtr* at = adr_type(); 1931 if (at != TypePtr::BOTTOM) { 1932 // Patch the existing phi to select an input from the merge: 1933 // Phi:AT1(...MergeMem(m0, m1, m2)...) into 1934 // Phi:AT1(...m1...) 1935 int alias_idx = phase->C->get_alias_index(at); 1936 for (uint i=1; i<req(); ++i) { 1937 Node *ii = in(i); 1938 if (ii->is_MergeMem()) { 1939 MergeMemNode* n = ii->as_MergeMem(); 1940 // compress paths and change unreachable cycles to TOP 1941 // If not, we can update the input infinitely along a MergeMem cycle 1942 // Equivalent code is in MemNode::Ideal_common 1943 Node *m = phase->transform(n); 1944 if (outcnt() == 0) { // Above transform() may kill us! 1945 return top; 1946 } 1947 // If transformed to a MergeMem, get the desired slice 1948 // Otherwise the returned node represents memory for every slice 1949 Node *new_mem = (m->is_MergeMem()) ? 1950 m->as_MergeMem()->memory_at(alias_idx) : m; 1951 // Update input if it is progress over what we have now 1952 if (new_mem != ii) { 1953 set_req(i, new_mem); 1954 progress = this; 1955 } 1956 } 1957 } 1958 } else { 1959 // We know that at least one MergeMem->base_memory() == this 1960 // (saw_self == true). If all other inputs also references this phi 1961 // (directly or through data nodes) - it is dead loop. 1962 bool saw_safe_input = false; 1963 for (uint j = 1; j < req(); ++j) { 1964 Node *n = in(j); 1965 if (n->is_MergeMem() && n->as_MergeMem()->base_memory() == this) 1966 continue; // skip known cases 1967 if (!is_unsafe_data_reference(n)) { 1968 saw_safe_input = true; // found safe input 1969 break; 1970 } 1971 } 1972 if (!saw_safe_input) 1973 return top; // all inputs reference back to this phi - dead loop 1974 1975 // Phi(...MergeMem(m0, m1:AT1, m2:AT2)...) into 1976 // MergeMem(Phi(...m0...), Phi:AT1(...m1...), Phi:AT2(...m2...)) 1977 PhaseIterGVN *igvn = phase->is_IterGVN(); 1978 Node* hook = new Node(1); 1979 PhiNode* new_base = (PhiNode*) clone(); 1980 // Must eagerly register phis, since they participate in loops. 1981 if (igvn) { 1982 igvn->register_new_node_with_optimizer(new_base); 1983 hook->add_req(new_base); 1984 } 1985 MergeMemNode* result = MergeMemNode::make(new_base); 1986 for (uint i = 1; i < req(); ++i) { 1987 Node *ii = in(i); 1988 if (ii->is_MergeMem()) { 1989 MergeMemNode* n = ii->as_MergeMem(); 1990 for (MergeMemStream mms(result, n); mms.next_non_empty2(); ) { 1991 // If we have not seen this slice yet, make a phi for it. 1992 bool made_new_phi = false; 1993 if (mms.is_empty()) { 1994 Node* new_phi = new_base->slice_memory(mms.adr_type(phase->C)); 1995 made_new_phi = true; 1996 if (igvn) { 1997 igvn->register_new_node_with_optimizer(new_phi); 1998 hook->add_req(new_phi); 1999 } 2000 mms.set_memory(new_phi); 2001 } 2002 Node* phi = mms.memory(); 2003 assert(made_new_phi || phi->in(i) == n, "replace the i-th merge by a slice"); 2004 phi->set_req(i, mms.memory2()); 2005 } 2006 } 2007 } 2008 // Distribute all self-loops. 2009 { // (Extra braces to hide mms.) 2010 for (MergeMemStream mms(result); mms.next_non_empty(); ) { 2011 Node* phi = mms.memory(); 2012 for (uint i = 1; i < req(); ++i) { 2013 if (phi->in(i) == this) phi->set_req(i, phi); 2014 } 2015 } 2016 } 2017 // now transform the new nodes, and return the mergemem 2018 for (MergeMemStream mms(result); mms.next_non_empty(); ) { 2019 Node* phi = mms.memory(); 2020 mms.set_memory(phase->transform(phi)); 2021 } 2022 if (igvn) { // Unhook. 2023 igvn->hash_delete(hook); 2024 for (uint i = 1; i < hook->req(); i++) { 2025 hook->set_req(i, NULL); 2026 } 2027 } 2028 // Replace self with the result. 2029 return result; 2030 } 2031 } 2032 // 2033 // Other optimizations on the memory chain 2034 // 2035 const TypePtr* at = adr_type(); 2036 for( uint i=1; i<req(); ++i ) {// For all paths in 2037 Node *ii = in(i); 2038 Node *new_in = MemNode::optimize_memory_chain(ii, at, NULL, phase); 2039 if (ii != new_in ) { 2040 set_req(i, new_in); 2041 progress = this; 2042 } 2043 } 2044 } 2045 2046 #ifdef _LP64 2047 // Push DecodeN/DecodeNKlass down through phi. 2048 // The rest of phi graph will transform by split EncodeP node though phis up. 2049 if ((UseCompressedOops || UseCompressedClassPointers) && can_reshape && progress == NULL) { 2050 bool may_push = true; 2051 bool has_decodeN = false; 2052 bool is_decodeN = false; 2053 for (uint i=1; i<req(); ++i) {// For all paths in 2054 Node *ii = in(i); 2055 if (ii->is_DecodeNarrowPtr() && ii->bottom_type() == bottom_type()) { 2056 // Do optimization if a non dead path exist. 2057 if (ii->in(1)->bottom_type() != Type::TOP) { 2058 has_decodeN = true; 2059 is_decodeN = ii->is_DecodeN(); 2060 } 2061 } else if (!ii->is_Phi()) { 2062 may_push = false; 2063 } 2064 } 2065 2066 if (has_decodeN && may_push) { 2067 PhaseIterGVN *igvn = phase->is_IterGVN(); 2068 // Make narrow type for new phi. 2069 const Type* narrow_t; 2070 if (is_decodeN) { 2071 narrow_t = TypeNarrowOop::make(this->bottom_type()->is_ptr()); 2072 } else { 2073 narrow_t = TypeNarrowKlass::make(this->bottom_type()->is_ptr()); 2074 } 2075 PhiNode* new_phi = new PhiNode(r, narrow_t); 2076 uint orig_cnt = req(); 2077 for (uint i=1; i<req(); ++i) {// For all paths in 2078 Node *ii = in(i); 2079 Node* new_ii = NULL; 2080 if (ii->is_DecodeNarrowPtr()) { 2081 assert(ii->bottom_type() == bottom_type(), "sanity"); 2082 new_ii = ii->in(1); 2083 } else { 2084 assert(ii->is_Phi(), "sanity"); 2085 if (ii->as_Phi() == this) { 2086 new_ii = new_phi; 2087 } else { 2088 if (is_decodeN) { 2089 new_ii = new EncodePNode(ii, narrow_t); 2090 } else { 2091 new_ii = new EncodePKlassNode(ii, narrow_t); 2092 } 2093 igvn->register_new_node_with_optimizer(new_ii); 2094 } 2095 } 2096 new_phi->set_req(i, new_ii); 2097 } 2098 igvn->register_new_node_with_optimizer(new_phi, this); 2099 if (is_decodeN) { 2100 progress = new DecodeNNode(new_phi, bottom_type()); 2101 } else { 2102 progress = new DecodeNKlassNode(new_phi, bottom_type()); 2103 } 2104 } 2105 } 2106 #endif 2107 2108 return progress; // Return any progress 2109 } 2110 2111 //------------------------------is_tripcount----------------------------------- 2112 bool PhiNode::is_tripcount() const { 2113 return (in(0) != NULL && in(0)->is_CountedLoop() && 2114 in(0)->as_CountedLoop()->phi() == this); 2115 } 2116 2117 //------------------------------out_RegMask------------------------------------ 2118 const RegMask &PhiNode::in_RegMask(uint i) const { 2119 return i ? out_RegMask() : RegMask::Empty; 2120 } 2121 2122 const RegMask &PhiNode::out_RegMask() const { 2123 uint ideal_reg = _type->ideal_reg(); 2124 assert( ideal_reg != Node::NotAMachineReg, "invalid type at Phi" ); 2125 if( ideal_reg == 0 ) return RegMask::Empty; 2126 assert(ideal_reg != Op_RegFlags, "flags register is not spillable"); 2127 return *(Compile::current()->matcher()->idealreg2spillmask[ideal_reg]); 2128 } 2129 2130 #ifndef PRODUCT 2131 void PhiNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const { 2132 // For a PhiNode, the set of related nodes includes all inputs till level 2, 2133 // and all outputs till level 1. In compact mode, inputs till level 1 are 2134 // collected. 2135 this->collect_nodes(in_rel, compact ? 1 : 2, false, false); 2136 this->collect_nodes(out_rel, -1, false, false); 2137 } 2138 2139 void PhiNode::dump_spec(outputStream *st) const { 2140 TypeNode::dump_spec(st); 2141 if (is_tripcount()) { 2142 st->print(" #tripcount"); 2143 } 2144 } 2145 #endif 2146 2147 2148 //============================================================================= 2149 const Type* GotoNode::Value(PhaseGVN* phase) const { 2150 // If the input is reachable, then we are executed. 2151 // If the input is not reachable, then we are not executed. 2152 return phase->type(in(0)); 2153 } 2154 2155 Node* GotoNode::Identity(PhaseGVN* phase) { 2156 return in(0); // Simple copy of incoming control 2157 } 2158 2159 const RegMask &GotoNode::out_RegMask() const { 2160 return RegMask::Empty; 2161 } 2162 2163 #ifndef PRODUCT 2164 //-----------------------------related----------------------------------------- 2165 // The related nodes of a GotoNode are all inputs at level 1, as well as the 2166 // outputs at level 1. This is regardless of compact mode. 2167 void GotoNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const { 2168 this->collect_nodes(in_rel, 1, false, false); 2169 this->collect_nodes(out_rel, -1, false, false); 2170 } 2171 #endif 2172 2173 2174 //============================================================================= 2175 const RegMask &JumpNode::out_RegMask() const { 2176 return RegMask::Empty; 2177 } 2178 2179 #ifndef PRODUCT 2180 //-----------------------------related----------------------------------------- 2181 // The related nodes of a JumpNode are all inputs at level 1, as well as the 2182 // outputs at level 2 (to include actual jump targets beyond projection nodes). 2183 // This is regardless of compact mode. 2184 void JumpNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const { 2185 this->collect_nodes(in_rel, 1, false, false); 2186 this->collect_nodes(out_rel, -2, false, false); 2187 } 2188 #endif 2189 2190 //============================================================================= 2191 const RegMask &JProjNode::out_RegMask() const { 2192 return RegMask::Empty; 2193 } 2194 2195 //============================================================================= 2196 const RegMask &CProjNode::out_RegMask() const { 2197 return RegMask::Empty; 2198 } 2199 2200 2201 2202 //============================================================================= 2203 2204 uint PCTableNode::hash() const { return Node::hash() + _size; } 2205 uint PCTableNode::cmp( const Node &n ) const 2206 { return _size == ((PCTableNode&)n)._size; } 2207 2208 const Type *PCTableNode::bottom_type() const { 2209 const Type** f = TypeTuple::fields(_size); 2210 for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL; 2211 return TypeTuple::make(_size, f); 2212 } 2213 2214 //------------------------------Value------------------------------------------ 2215 // Compute the type of the PCTableNode. If reachable it is a tuple of 2216 // Control, otherwise the table targets are not reachable 2217 const Type* PCTableNode::Value(PhaseGVN* phase) const { 2218 if( phase->type(in(0)) == Type::CONTROL ) 2219 return bottom_type(); 2220 return Type::TOP; // All paths dead? Then so are we 2221 } 2222 2223 //------------------------------Ideal------------------------------------------ 2224 // Return a node which is more "ideal" than the current node. Strip out 2225 // control copies 2226 Node *PCTableNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2227 return remove_dead_region(phase, can_reshape) ? this : NULL; 2228 } 2229 2230 //============================================================================= 2231 uint JumpProjNode::hash() const { 2232 return Node::hash() + _dest_bci; 2233 } 2234 2235 uint JumpProjNode::cmp( const Node &n ) const { 2236 return ProjNode::cmp(n) && 2237 _dest_bci == ((JumpProjNode&)n)._dest_bci; 2238 } 2239 2240 #ifndef PRODUCT 2241 void JumpProjNode::dump_spec(outputStream *st) const { 2242 ProjNode::dump_spec(st); 2243 st->print("@bci %d ",_dest_bci); 2244 } 2245 2246 void JumpProjNode::dump_compact_spec(outputStream *st) const { 2247 ProjNode::dump_compact_spec(st); 2248 st->print("(%d)%d@%d", _switch_val, _proj_no, _dest_bci); 2249 } 2250 2251 void JumpProjNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const { 2252 // The related nodes of a JumpProjNode are its inputs and outputs at level 1. 2253 this->collect_nodes(in_rel, 1, false, false); 2254 this->collect_nodes(out_rel, -1, false, false); 2255 } 2256 #endif 2257 2258 //============================================================================= 2259 //------------------------------Value------------------------------------------ 2260 // Check for being unreachable, or for coming from a Rethrow. Rethrow's cannot 2261 // have the default "fall_through_index" path. 2262 const Type* CatchNode::Value(PhaseGVN* phase) const { 2263 // Unreachable? Then so are all paths from here. 2264 if( phase->type(in(0)) == Type::TOP ) return Type::TOP; 2265 // First assume all paths are reachable 2266 const Type** f = TypeTuple::fields(_size); 2267 for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL; 2268 // Identify cases that will always throw an exception 2269 // () rethrow call 2270 // () virtual or interface call with NULL receiver 2271 // () call is a check cast with incompatible arguments 2272 if( in(1)->is_Proj() ) { 2273 Node *i10 = in(1)->in(0); 2274 if( i10->is_Call() ) { 2275 CallNode *call = i10->as_Call(); 2276 // Rethrows always throw exceptions, never return 2277 if (call->entry_point() == OptoRuntime::rethrow_stub()) { 2278 f[CatchProjNode::fall_through_index] = Type::TOP; 2279 } else if( call->req() > TypeFunc::Parms ) { 2280 const Type *arg0 = phase->type( call->in(TypeFunc::Parms) ); 2281 // Check for null receiver to virtual or interface calls 2282 if( call->is_CallDynamicJava() && 2283 arg0->higher_equal(TypePtr::NULL_PTR) ) { 2284 f[CatchProjNode::fall_through_index] = Type::TOP; 2285 } 2286 } // End of if not a runtime stub 2287 } // End of if have call above me 2288 } // End of slot 1 is not a projection 2289 return TypeTuple::make(_size, f); 2290 } 2291 2292 //============================================================================= 2293 uint CatchProjNode::hash() const { 2294 return Node::hash() + _handler_bci; 2295 } 2296 2297 2298 uint CatchProjNode::cmp( const Node &n ) const { 2299 return ProjNode::cmp(n) && 2300 _handler_bci == ((CatchProjNode&)n)._handler_bci; 2301 } 2302 2303 2304 //------------------------------Identity--------------------------------------- 2305 // If only 1 target is possible, choose it if it is the main control 2306 Node* CatchProjNode::Identity(PhaseGVN* phase) { 2307 // If my value is control and no other value is, then treat as ID 2308 const TypeTuple *t = phase->type(in(0))->is_tuple(); 2309 if (t->field_at(_con) != Type::CONTROL) return this; 2310 // If we remove the last CatchProj and elide the Catch/CatchProj, then we 2311 // also remove any exception table entry. Thus we must know the call 2312 // feeding the Catch will not really throw an exception. This is ok for 2313 // the main fall-thru control (happens when we know a call can never throw 2314 // an exception) or for "rethrow", because a further optimization will 2315 // yank the rethrow (happens when we inline a function that can throw an 2316 // exception and the caller has no handler). Not legal, e.g., for passing 2317 // a NULL receiver to a v-call, or passing bad types to a slow-check-cast. 2318 // These cases MUST throw an exception via the runtime system, so the VM 2319 // will be looking for a table entry. 2320 Node *proj = in(0)->in(1); // Expect a proj feeding CatchNode 2321 CallNode *call; 2322 if (_con != TypeFunc::Control && // Bail out if not the main control. 2323 !(proj->is_Proj() && // AND NOT a rethrow 2324 proj->in(0)->is_Call() && 2325 (call = proj->in(0)->as_Call()) && 2326 call->entry_point() == OptoRuntime::rethrow_stub())) 2327 return this; 2328 2329 // Search for any other path being control 2330 for (uint i = 0; i < t->cnt(); i++) { 2331 if (i != _con && t->field_at(i) == Type::CONTROL) 2332 return this; 2333 } 2334 // Only my path is possible; I am identity on control to the jump 2335 return in(0)->in(0); 2336 } 2337 2338 2339 #ifndef PRODUCT 2340 void CatchProjNode::dump_spec(outputStream *st) const { 2341 ProjNode::dump_spec(st); 2342 st->print("@bci %d ",_handler_bci); 2343 } 2344 #endif 2345 2346 //============================================================================= 2347 //------------------------------Identity--------------------------------------- 2348 // Check for CreateEx being Identity. 2349 Node* CreateExNode::Identity(PhaseGVN* phase) { 2350 if( phase->type(in(1)) == Type::TOP ) return in(1); 2351 if( phase->type(in(0)) == Type::TOP ) return in(0); 2352 // We only come from CatchProj, unless the CatchProj goes away. 2353 // If the CatchProj is optimized away, then we just carry the 2354 // exception oop through. 2355 CallNode *call = in(1)->in(0)->as_Call(); 2356 2357 return ( in(0)->is_CatchProj() && in(0)->in(0)->in(1) == in(1) ) 2358 ? this 2359 : call->in(TypeFunc::Parms); 2360 } 2361 2362 //============================================================================= 2363 //------------------------------Value------------------------------------------ 2364 // Check for being unreachable. 2365 const Type* NeverBranchNode::Value(PhaseGVN* phase) const { 2366 if (!in(0) || in(0)->is_top()) return Type::TOP; 2367 return bottom_type(); 2368 } 2369 2370 //------------------------------Ideal------------------------------------------ 2371 // Check for no longer being part of a loop 2372 Node *NeverBranchNode::Ideal(PhaseGVN *phase, bool can_reshape) { 2373 if (can_reshape && !in(0)->is_Loop()) { 2374 // Dead code elimination can sometimes delete this projection so 2375 // if it's not there, there's nothing to do. 2376 Node* fallthru = proj_out(0); 2377 if (fallthru != NULL) { 2378 phase->is_IterGVN()->replace_node(fallthru, in(0)); 2379 } 2380 return phase->C->top(); 2381 } 2382 return NULL; 2383 } 2384 2385 #ifndef PRODUCT 2386 void NeverBranchNode::format( PhaseRegAlloc *ra_, outputStream *st) const { 2387 st->print("%s", Name()); 2388 } 2389 #endif